FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION [See section 10, Rule 13] MANUFACTURING METHOD OF DISCHARGE VALVE MECHANISM FOR COMPRESSOR AND COMPRESSOR INCLUDING DISCHARGE VALVE MECHANISM; MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED 2 DESCRIPTION Technical Field [0001] The present disclosure relates to a manufacturing method of a discharge valve 5 mechanism provided at a flange portion of a compressor used for a cooling device of an air conditioner or a refrigerator. The present disclosure further relates to a compressor including such a discharge valve mechanism and used for a cooling device of an air conditioner or a refrigerator. Background Art 10 [0002] Regarding a compressor, such as a rotary compressor, used for a cooling device of an air conditioner or a refrigerator, a flange portion of a bearing used for the compressor has a refrigerant-gas hole extending to a cylinder chamber. A discharge valve capable of opening and closing the refrigerant-gas hole and a valve retainer are 15 mounted on the flange portion so as to cover the refrigerant-gas hole, and a valve mounting mechanism is thus formed at the flange portion. The valve mounting mechanism adjusts the flow of the refrigerant gas inside the compressor. A riveting method is a known method of mounting the discharge valve and the valve retainer on the flange portion. 20 [0003] The method of mounting the discharge valve and the valve retainer on the bearing of the compressor by the riveting method is as follows. A recessed portion is formed in a one-side surface of the flange portion of the bearing, and the discharge valve and the valve retainer are disposed in the recessed portion. A rivet is inserted 25 into a rivet hole formed in the recessed portion and caused to pass through the flange portion, the discharge valve, and the valve retainer. A punch of a riveting machine is caused to push the upper end of the inserted rivet and squashes (swages) the upper 3 end of the rivet to form a rivet head. Such a rivet head fixes the discharge valve and the valve retainer in the recessed portion of the flange portion. [0004] The push-in amount by which the riveting machine pushes the punch in is 5 controlled so that the push-in depth is maintained constant. However, due to a factor such as abrasion of a grindstone or expansion caused by grinding heat when the flange portion is manufactured, the thickness of the flange portion varies from one bearing to another, and the thickness of the bottom of the recessed portion of the flange portion also varies. Such variations cause a problem of an excess or 10 inadequate push-in depth of the punch relative to the bottom of the recessed portion of the flange portion. For example, when the thickness of the bottom of the recessed portion of the flange portion is larger than the designed thickness due to variation in the thickness, the punch is caused to excessively push relative to the bottom of the recessed portion because the push-in amount by which the riveting machine pushes 15 the punch in is maintained constant. In such a case, there is caused inadequate riveting, that is, a portion of the rivet spreads into a gap between the discharge valve and the valve retainer, and such inadequate riveting may cause the failure of the discharge valve or the valve retainer during the operation of the compressor. On the other hand, when the thickness of the bottom of the recessed portion of the flange 20 portion is smaller than the designed thickness due to variation in the thickness, the punch is caused to inadequately push relative to the bottom of the recessed portion. In such a case, there is caused inadequate riveting, that is, the discharge valve and the valve retainer are not adequately fixed to the flange portion with the rivet, and such inadequate riveting may cause the misalignment or detachment of the discharge 25 valve or the valve retainer during the operation of the compressor. [0005] Thus, as a measure to address inadequate riveting, there has been proposed a method in which a double circle mark, which represents the upper limit and the lower limit of the normal range of the outside diameter of the rivet head, is put on a surface, 30 to be subjected to riveting, of the valve retainer, and the size of the rivet head after 4 riveting and the size of the mark are visually compared. In this method, riveting is determined to be inadequate when the size of the outside diameter of the rivet head after riveting exceeds the circle of the mark representing the upper limit or does not exceed the circle of the mark representing the lower limit (for example, refer to Patent 5 Literature 1). Citation List Patent Literature [0006] Patent Literature 1: Japanese Unexamined Patent Application Publication No. 10 2010-236564 Summary of Invention Technical Problem [0007] However, there has been a problem that, in the method, inadequate riveting 15 can be detected but cannot be suppressed from being caused. [0008] The present disclosure has been made to solve such an above-described problem, and an object of the present disclosure is to provide a manufacturing method of a discharge valve mechanism capable of suppressing inadequate riveting 20 during mounting of a discharge valve and a valve retainer on a flange portion, from being caused even when the thickness of the flange portion varies and also to provide a compressor including the discharge valve mechanism. Solution to Problem [0009] 25 To solve the above-described problem, a manufacturing method of a valve mounting mechanism according to an embodiment of the present disclosure is for manufacturing a discharge valve mechanism in which, on a flange portion having a discharge hole and a rivet hole, a discharge valve that covers the discharge hole and a valve retainer that regulates deformation of the discharge valve are mounted with a 30 rivet, and the manufacturing method includes forming a reference surface and a valve 5 mounting surface being at a predetermined distance h1 to the reference surface in the thickness direction of the flange portion, in a one-side surface of the flange portion with the same tool. Also included are placing the discharge valve and the valve retainer on the valve mounting surface and inserting the rivet into the rivet hole 5 formed in the valve mounting surface, into a first opening of the discharge valve, and into a second opening of the valve retainer from the other side surface of the flange portion. Further included are measuring the position of the reference surface in relation to the other side surface of the flange portion and fixing the discharge valve and the valve retainer to the valve mounting surface by the rivet being deformed by 10 being pressed by a punch from the one-side surface based on the distance h1 of the valve mounting surface to the reference surface in the depth direction, the thickness of the discharge valve, and the thickness of the valve retainer. Advantageous Effects of Invention [0010] 15 With the manufacturing method of the valve mounting mechanism, according to an embodiment of the present disclosure, the reference surface and the valve mounting surface being at a predetermined distance from the reference surface in the depth direction of the flange portion are formed on the one-side surface of the flange portion with the same tool, the depth of the reference surface is measured, and the 20 punch presses the rivet from the one-side surface based on the predetermined distance from the reference surface in the depth direction and the thicknesses of the discharge valve and the valve retainer. Thus, even when the thickness of the flange portion varies, the push-in depth of the punch relative to the valve mounting surface can be maintained constant within the accuracy of the tool, and inadequate riveting 25 during the mounting of the discharge valve and the valve retainer on the flange portion with the rivet can be suppressed from being caused. Brief Description of Drawings [0011] [Fig. 1] Fig. 1 is a vertical sectional view of a rotary compressor according to 30 Embodiment 1 of the present disclosure. 6 [Fig. 2] Fig. 2 is a horizontal sectional view of a cylinder, taken along line A-A', of the rotary compressor according to Embodiment 1 of the present disclosure. [Fig. 3] Fig. 3 is a top view of an upper bearing of the rotary compressor according to Embodiment 1 of the present disclosure. 5 [Fig. 4] Fig. 4 is a top view of the upper bearing and a valve mounting mechanism according to Embodiment 1 of the present disclosure. [Fig. 5] Fig. 5 is a perspective view of the structure of a region surrounding a discharge valve and a valve retainer of the valve mounting mechanism according to Embodiment 1 of the present disclosure. 10 [Fig. 6] Fig. 6 is a top view of the structure of the discharge valve according to Embodiment 1 of the present disclosure. [Fig. 7] Fig. 7 is a top view of the structure of the valve retainer according to Embodiment 1 of the present disclosure. [Fig. 8] Fig. 8 is a top view illustrating the position of line B-B' of the valve 15 mounting mechanism according to Embodiment 1 of the present disclosure. [Fig. 9] Fig. 9 is a sectional view of the valve mounting mechanism according to Embodiment 1 of the present disclosure when the section taken along line B-B' is illustrated on a plane. [Fig. 10] Fig. 10 is a schematic view of a riveting machine and a flange portion 20 according to Embodiment 1 of the present disclosure when the discharge valve and the valve retainer are riveted. [Fig. 11] Fig. 11 is a schematic view of the riveting machine and the flange portion according to Embodiment 1 of the present disclosure when the discharge valve and the valve retainer are riveted. 25 [Fig. 12] Fig. 12 is a flowchart of the process of a manufacturing method of the valve mounting mechanism according to Embodiment 1 of the present disclosure. [Fig. 13] Fig. 13 is a schematic view of a manufacturing apparatus of the valve mounting mechanism according to Embodiment 1 of the present disclosure. Description of Embodiment 30 [0012] 7 Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings. The parts denoted by the same reference here are the same parts, and this is common in the entirety of the description. The forms of the constituting elements represented in the entire description are merely 5 examples, and the forms of the constituting elements are not limited to the forms thereof in the description. In particular, the shapes of the constituting elements are not limited to the shapes of the constituting elements in the embodiment. In the drawings, the structures of the actual parts are sometimes simplified. In addition, in the drawings, the sizes and/or the positional relationships of the constituting objects 10 sometimes differ from the sizes and/or the positional relationships of the actual constituting objects. In the following description, the terms representing directions (such as "axial direction", "above", "upper side", "below", and "lower side") are appropriately used for facilitating understanding. However, such terms are used for an illustration purpose 15 and are not intended to limit the present disclosure. Note that, in the present description, the orientation of the axis of a shaft when the shaft is mounted in a compressor is referred to as the "axial direction". In addition, "above", "upper side", "below", and "lower side" represent the relative positional relationships of the constituting parts when the constituting parts are mounted in the compressor and if 20 the compressor is viewed from a position in front of the compressor. [0013] Embodiment 1 Fig. 1 is a sectional view of the overall structure of a rotary compressor 1 that is a compressor according to Embodiment 1 of the present disclosure. When in use, 25 the rotary compressor 1 is incorporated in a cooling circuit as a cooling device of an air conditioner or a refrigerator. [0014] Fig. 1 is a sectional view of the compressor 1 according to Embodiment 1. 30 The compressor 1 is a rotary compressor. 8 The compressor 1 has an accumulator 2, a sealed container 10, a suction pipe 14, a discharge pipe 15, a motor 20, a shaft 30, a cylinder 40, an upper bearing 50, and a lower bearing 60. [0015] 5 The sealed container 10 has a body portion 11, an upper lid portion 12, and a lower lid portion 13. The body portion 11 has, for example, a hollow cylindrical shape. The upper lid portion 12 and the lower lid portion 13 are joined to the body portion 11. The suction pipe 14 is mounted on the body portion 11. The 10 accumulator 2 is mounted onto the suction pipe 14, and, through the suction pipe 14, refrigerant is introduced from the accumulator 2 into a suction chamber 46 (illustrated in Fig. 2) of the cylinder 40. The discharge pipe 15 is mounted on the upper lid portion 12. The sealed container 10 discharges, through the discharge pipe 15, the refrigerant that has been 15 compressed by an eccentric ring 32, which will be described later. In a bottom portion of the sealed container 10, a reservoir space (not illustrated) for trapping lubricating oil is provided. [0016] The motor 20 generates power for rotating the shaft 30. The motor 20 has a 20 stator 21 and a rotor 22. The stator 21 is fixed to the body portion 11 of the sealed container 10. The rotor 22 is rotated by magnetically interacting with the stator 21. [0017] The shaft 30 is fixed to the rotor 22. The shaft 30 transmits the power of the 25 motor 20 to a compression mechanism 35. On the shaft 30, an eccentric shaft portion 31 is mounted. The eccentric shaft portion 31 is a portion that has a shape of a column having a diameter larger than the diameter of the shaft 30 and being eccentric to the central axis C of the shaft 30 in the radial direction of the shaft 30 when being mounted on 30 the shaft 30. The eccentric ring 32 having a hollow cylindrical shape is fitted onto 9 the eccentric shaft portion 31 so as to slide along the eccentric shaft portion 31, that is, so as to rotate. [0018] The shaft 30 is inserted into the cylinder 40. The eccentric shaft portion 31 5 and the eccentric ring 32 are positioned inside the cylinder 40. In addition, the shaft 30 is held by the upper bearing 50 on the upper side relative to the cylinder 40 and by the lower bearing 60 on the lower side relative to the cylinder 40 so that the shaft 30 can rotate. The upper bearing 50 and the lower bearing 60 are vertically arranged with the cylinder 40 interposed therebetween. 10 [0019] Next, the cylinder 40, the upper bearing 50, and the lower bearing 60 will be described with reference to, in addition to Fig. 1, Fig. 2 and Fig. 3. [0020] Fig. 2 is a sectional view of the cylinder 40 taken along cutting line A-A'. 15 The cylinder 40 has a shape having a hollow cylindrical portion 41 whose upper end and lower end are open and having a protruding portion 42 protruding in the direction from the inside toward the outer circumference of the hollow cylindrical portion 41. Note that, in Fig. 2, the shape of the upper bearing 50 is illustrated by a dotted line to give the positional relationship between the cylinder 40 and the upper 20 bearing 50. The specific shapes of the upper bearing 50 and the lower bearing 60 will be described with reference to Fig. 3 and Fig. 4. [0021] As Fig. 2 illustrates, the hollow cylindrical portion 41 is arranged coaxially with the shaft 30 with the central axis C as the axis. 25 The inside diameter of the hollow cylindrical portion 41 is sized so that the outer circumference of the above-described eccentric ring 32 is in contact with the hollow cylindrical portion 41. The outside diameter of the hollow cylindrical portion 41 is smaller than the inside diameter of the body portion 11 of the sealed container 10, for preventing the hollow cylindrical portion 41 from deforming due to contact with 30 the sealed container 10. 10 Inside the hollow cylindrical portion 41, the shaft 30 is rotated by the motor 20, and the eccentric shaft portion 31 thus rotates eccentrically to the central axis C of the shaft 30. Accordingly, the eccentric ring 32 rotates along the eccentric shaft portion 31. 5 [0022] The protruding portion 42 has a vane slot 43 extending in the radial direction from the inner circumferential surface to the outer circumferential surface of the hollow cylindrical portion 41. A vane 45 is installed in the vane slot 43. In detail, the vane 45 is inserted into 10 the vane slot 43 with a leading end of the vane 45 being exposed inside the hollow cylindrical portion 41. The vane 45 here is a part that is in contact with the eccentric ring 32 and divides the inside of the hollow cylindrical portion 41 into the suction chamber 46, into which refrigerant is sucked through a suction hole 48, which will be described later, 15 and a compression chamber 47 in which the refrigerant inside the hollow cylindrical portion 41 is compressed. [0023] The vane slot 43 is connected to a spring accommodation hole 49. A spring 49a is accommodated in the spring accommodation hole 49 in a compressed manner, 20 and the spring 49a urges the vane 45 toward the inner circumference region of the cylinder 40. The vane 45 is brought into pressure contact with the eccentric ring 32. [0024] The protruding portion 42 has the suction hole 48 passing through from the outer circumferential surface of the protruding portion 42 to the inner circumferential 25 surface of the hollow cylindrical portion 41, for supplying refrigerant into the hollow cylindrical portion 41. The suction pipe 14 is inserted into the suction hole 48. Due to the abovedescribed rotation of the eccentric shaft portion 31 and rotation of the eccentric ring 32, refrigerant, which is refrigerant, is sucked into the hollow cylindrical portion 41 30 through the suction hole 48. 11 [0025] Note that a flange portion 51 of the upper bearing 50 and a flange portion 61 of the lower bearing 60 each cover the hollow cylindrical portion 41. The dotted line in Fig. 2 illustrates the position of the outer contour of the flange portion 51 provided on 5 the cylinder 40. [0026] Fig. 3 is a top view of the upper bearing 50. The flange portion 51 of the upper bearing 50 has a discharge hole 52 for discharging refrigerant from the compression chamber 47 provided inside the hollow 10 cylindrical portion 41. Similarly, although not illustrated, the flange portion of the lower bearing 60 has a discharge hole for discharging refrigerant from the compression chamber 47 provided inside the hollow cylindrical portion 41. The refrigerant that has been sucked through the suction hole 48 is compressed by the eccentric shaft portion 31 and the eccentric ring 32 rotating and is 15 discharged through the discharge hole 52 into the sealed container 10. [0027] As Fig. 1 and Fig. 2 illustrate, the compression mechanism 35 has the cylinder 40, the upper bearing 50 and the lower bearing 60 that hold the cylinder 40 therebetween, the shaft 30, the eccentric shaft portion 31, the eccentric ring 32, the 20 suction hole 48, and the vane 45. The eccentric ring 32 is fitted onto the eccentric shaft portion 31 of the shaft 10 and eccentrically rotates inside the cylinder chamber. The eccentric ring 11 is fitted onto the eccentric shaft portion 31 of the shaft 10 so that the inner circumference of the eccentric ring 11 can slide on the eccentric shaft portion 31. 25 [0028] The upper bearing 50 has the flange portion 51 having a flattened toroidal shape and a bearing portion 53 having a hollow cylindrical shape and provided on the upper side relative to the flange portion 51. [0029] 12 The bearing portion 53 holds the shaft 30 so that the shaft 30 can rotate, and the bearing portion 53 is constituted by a bearing such as a sliding bearing or a rolling bearing. As Fig. 1 illustrates, the axis C represents the orientation of the shaft 30 when the shaft 30 is held by the bearing portion. In the present description, the 5 orientation parallel to the axis C is referred to as the axial direction or the vertical direction. [0030] The outside diameter of the flange portion 51 is smaller than the inside diameter of the sealed container 10 but is larger than the outside diameter of the 10 hollow cylindrical portion 41 of the cylinder 40. The flange portion 51 abuts an edge face in an upper surface region of the cylinder 40 and covers the opened upper side of the hollow cylindrical portion 41 of the cylinder 40. [0031] As with the upper bearing 50, the lower bearing 60 has the flange portion 61 15 having a flattened toroidal shape and a bearing portion 63 having a hollow cylindrical shape and provided on the lower side relative to the flange portion 61. [0032] The bearing portion 63 holds the shaft 30 so that the shaft 30 can rotate, and the bearing portion 63 is constituted by a bearing such as a sliding bearing or a rolling 20 bearing. [0033] The outside diameter of the flange portion 61 is smaller than the inside diameter of the sealed container 10 but is larger than the outside diameter of the hollow cylindrical portion 41 of the cylinder 40. The flange portion 61 abuts an edge 25 face in a lower surface region of the cylinder 40 and covers the opened lower side of the hollow cylindrical portion 41 of the cylinder 40. [0034] As Fig. 3 illustrates, the upper surface of the flange portion 51 has the discharge hole 52 and a rivet hole 54 through which the rivet passes, the holes 30 vertically passing through the flange portion 51. 13 [0035] A valve seat 55 being a first recessed portion is formed in the upper surface of the flange portion 51 by the upper surface of the flange portion 51 being cut with a cutting tool such as an end mill tool. 5 The valve seat 55 includes the discharge hole 52 and the rivet hole 54. [0036] As Fig. 3 illustrates, the valve seat 55 has a circular region 55a formed around the discharge hole 52 and a linear region 55b connected to the circular region 55a and extending linearly. The bottom surface of the linear region 55 serves as a valve 10 mounting surface 56. The valve mounting surface 56 includes the rivet hole 54. As Fig. 10, which will be referred to later, illustrates, the circular region 55a has a region D that is a circular region being slightly larger than the discharge hole 52 and surrounding the discharge hole 52, and the region D is at a level lower than the level of the valve mounting surface 56. The region D has a convex shape rising toward 15 an opening end of the discharge hole 52. Such a structure produces the following effects. When a discharge valve 57 and a valve retainer 58 are mounted on the valve mounting surface 56, refrigerant easily flows from the compression chamber 47 through the discharge hole 52 during the operation of the compression mechanism 35, and backflow of the refrigerant to the compression chamber 47 is prevented. 20 The rivet hole 54 continuously extends, in the axial direction, from the valve mounting surface 56 to the lower surface of the flange portion 51. The discharge hole 52 continuously extends, in the axial direction, from a surface of the region D to the lower surface of the flange portion 51. [0037] 25 Note that Fig. 3 illustrates the linear region 55 and the valve mounting surface 56 formed in the upper surface of the flange portion 51 with an end mill tool. The linear region 55b has a width of D1, the width D1 is larger than the diameter of the rivet hole 54, and the terminal end portion of the linear region 55b is constituted by an arc of a circle having a diameter of D1. 30 [0038] 14 The upper surface of the flange portion 51 has a reference-surface machined hole 72 being a second recessed portion and spaced apart from the valve mounting surface 56, and the reference-surface machined hole 72 has a diameter of D2 as large as the diameter D1. The reference-surface machined hole 72 is formed by the 5 upper surface of the flange portion 51 being cut with a cutting tool such as the same end mill tool used to form the linear region 55. The bottom surface of the referencesurface machined hole 72 serves as a reference surface 73. [0039] Fig. 4 is a top view of the upper bearing 50. 10 In Fig. 4, on the upper surface of the flange portion 51, the discharge valve 57 having a flat spring shape and the valve retainer 58 layered on and mounted on the discharge valve 57 are arranged on the valve mounting surface 56 so as to cover the discharge hole 52. The top of a rivet 16 (the rivet head) can be seen on the valve retainer 58. 15 In Embodiment 1, the structure in which the upper bearing 50 has the bearing portion 53 and the flange portion 51, and the discharge valve 57 and the valve retainer 58 are mounted on the valve mounting surface 56 of the flange portion 51 with the rivet 16 is referred to as a valve mounting mechanism 200. [0040] 20 Fig. 5 is a perspective view of the structures of the discharge valve 57 and the valve retainer 58 that are positioned on the valve mounting surface 56. The discharge valve 57 and the valve retainer 58 are both mounted in the valve seat 55 in a cantilevered state by using the single rivet 16 passing through the rivet hole 54. The top of the rivet 16 is fixed by being swaged to form the rivet head on 25 the valve retainer 58. Note that, in Fig. 5, the region D is omitted for simple illustration. [0041] As Fig. 5 illustrates, a released end 59 that is the other end of the discharge valve 57 is not fixed with a rivet 16 and can move upward. With such a structure, 30 when the pressure of the refrigerant compressed in the cylinder 40 exceeds a 15 predetermined discharge pressure, the released end 59 of the discharge valve 57 disposed on the flange portion 51 elastically deforms toward the valve retainer 58 due to the discharge pressure of the refrigerant. The discharge valve 57 that has elastically deformed opens the discharge hole 52, and the compressed refrigerant is 5 discharged into the sealed container 10 through the discharge hole 52. [0042] The valve retainer 58 is a device for regulating elastic deformation of the discharge valve 57. The valve retainer 58 has a clinging preventive opening 74 in the other end. When the valve retainer 58 is riveted on the valve mounting surface 10 56, the clinging preventive opening 74 is at a position at which the clinging preventive opening 74 overlaps the discharge hole 52 in the direction orthogonal to the upper surface of the flange portion 51. The clinging preventive opening 74 is provided for preventing the released end 59 of the discharge valve 57 from clinging to the valve retainer 58. 15 The discharge valve 57 functions as a check valve that prevents the highpressure refrigerant inside the sealed container 10 from flowing back into the compression chamber 47 during a compression process. The discharge valve 57 also functions as a check valve when the compressor 1 is stopped. [0043] 20 Fig. 6 is a top view of the structure of the discharge valve 57. Fig. 7 is a top view of the structure of the valve retainer 58. [0044] As Fig. 6 illustrates, one end of the discharge valve 57 has a first opening 70. As Fig. 7 illustrates, one end of the valve retainer 58 has a second opening 71. The 25 rivet 16 inserted into the rivet hole 54 from the lower surface of the flange portion 51 is inserted into the first opening 70 of the discharge valve 57 and the second opening 71 of the valve retainer 58. The top of the rivet 16 that has been inserted into the first opening 70 of the discharge valve 57 and the second opening 71 of the valve retainer 58 is squashed, from above, by a punch 80 of a riveting machine 300 in Fig. 16 10, which will be described later, and the discharge valve 57 and the valve retainer 58 are riveted on the valve mounting surface 56 of the flange portion 51. [0045] The structure of each of the valve mounting surface 56, the discharge hole 52, 5 the discharge valve 57, and the valve retainer 58 and its vicinity that are formed on the upper surface of the flange portion 51 of the upper bearing 50 has the same structure as the structure of an equivalent one of the valve mounting surface, the discharge hole, the discharge valve, and the valve retainer and its vicinity that are formed on the lower surface of the flange portion of the lower bearing 60 when the 10 flange portion 51 is flipped vertically. In addition, a common mounting method is used to mount the discharge valve and the valve retainer on the flange portion of each of the upper bearing 50 and the lower bearing 60. Due to such features, in the present description, the structure of the upper surface of the flange portion 51 of the upper bearing 50 will be described, and the structure of the lower surface of the 15 flange portion of the lower bearing 8 will not be described. [0046] A valve mounting mechanism 100 according to Embodiment 1 is manufactured by a manufacturing method in which riveting is performed with the reference surface 73 serving as a reference. Hereinafter, the manufacturing method of the valve 20 mounting mechanism 100, through riveting with the rivet 16, according to Embodiment 1 will be described. [0047] Fig. 9 is a sectional view, that is, the planarly developed section, taken along line B-B' in Fig. 8, of the flange portion 51 provided with the valve mounting 25 mechanism 100. Line B-B' has a line passing through the center of the referencesurface machined hole 72 and a line passing through the center of the rivet hole 54 in a direction orthogonal to the direction where the linear region 55b extends. [0048] The reference surface 73 and the valve mounting surface 56 are formed by the 30 one-side surface, that is, the upper surface of the flange portion 51 being cut with the 17 same cutting tool (not illustrated). The reference surface 73 and the valve mounting surface 56 are formed so as to be parallel to the other side surface, that is, the lower surface of the flange portion 51. [0049] 5 As Fig. 9 illustrates, the reference surface 73 and the valve mounting surface 56 are formed in the upper surface of the flange portion 51 so that the depth from the upper surface of the flange portion 51 to the valve mounting surface 56 is larger than the depth from the upper surface of the flange portion 51 to the reference surface 73. The reference surface 73 is formed so that the depth of the reference surface 73 from 10 the upper surface of the flange portion 51 is 1 mm or less. The reference surface 73 and the valve mounting surface 56 are formed with the same processing machine and the same cutting tool, and a difference h1 between the depth from the upper surface of the flange portion 51 to the valve mounting surface 56 and the depth from the upper surface of the flange portion 51 to the 15 reference surface 73 is thereby constant within the variation range of up to 0.02 mm, even when variation in the thickness of the flange portion 51 arises. [0050] In Embodiment 1, the depth of the reference surface 73 is measured by a measuring element 81 of the riveting machine 300, and, with the measured depth of 20 the reference surface 73 as a reference value, the position that is h1 lower than the reference value is considered to be the depth of the valve mounting surface 56. The lowering amount by which the punch 80, which will be described later, is lowered is determined based on the depth of the valve mounting surface 56, and riveting is performed. 25 [0051] Note that, as Fig. 3 illustrates, the width D1 of the linear region 55b, which extends linearly from the circular region 55a formed around the discharge hole 52 in the upper surface of the flange portion 51, is as large as the diameter D2 of the reference-surface machined hole 72. Thus, when the upper surface of the flange 30 portion 51 is cut, by using a machine such as an NC milling machine, with a cutting 18 tool such as an end mill tool, the valve mounting surface 56 and the reference-surface machined hole 72 can be formed with the end mill having one diameter, without using plural end mills having different diameters. Because the above-described processing saves time and effort for exchanging end mills when the valve mounting 5 surface 56 and the reference-surface machined hole 72 are processed, the valve mounting surface 56 and the reference-surface machined hole 72 can easily be processed. [0052] Note that the valve seat 55 has, at the bottom, the valve mounting surface 56 10 on which the discharge valve 57 and the valve retainer 58 are mounted. The upper bearing 50, the discharge valve 57, the valve retainer 58, and the rivet 16 constitute a compressor-use valve mounting mechanism 100. [0053] Note that the width D1 is as large as the diameter D2 in Embodiment 1. 15 However, even when the diameter of a tool such as an end mill for forming the reference-surface machined hole 72 is smaller than the width D1 of the linear region 55b that is a portion of the valve seat 55, and D1 > D2 is thus satisfied, the relationship between the width D1 and the diameter D2 may be D1 > D2 as long as the same tool and the same processing machine are used in processing the valve 20 seat 55 and the reference-surface machined hole 72. Similarly, the relationship D1 < D2 is also acceptable as long as the same tool and the same processing machine are used for processing the linear region 55b that is a portion of the valve seat 55 and the reference-surface machined hole 72. [0054] 25 The reference-surface machined hole 72 is formed in the upper surface of the flange portion 51 so that, when the flange portion 51 is set on a stage 75 of the riveting machine 200 and if the punch 80 for riveting is positioned directly above the rivet 16, the reference surface 73 is positioned directly below a measuring element 86 of a measuring device 84 of the riveting machine 200. Thus, there is no need to 30 move the stage 75 when the measuring element 86 measures the reference surface 19 73, and riveting is performed with the punch 80 based on the measured value of the reference surface 73. Consequently, a riveting step is simplified. However, this is an example, and the reference-surface machined hole 72 may be formed at any position spaced apart from the valve seat 55 in the upper surface of the flange portion 5 51 as long as the function of the compression mechanism 35 is not impaired. [0055] In addition, the valve mounting surface 56 and the reference surface 73 are parallel to one another, and, with the reference surface 73 as a reference, the push-in depth by which a riveting portion is caused to push relative to the valve mounting 10 surface is determined to perform riveting. In addition, the reference surface 73 and the valve mounting surface 56 are formed so as to be parallel to the other side surface, that is, the lower surface of the flange portion 51, and the lower surface of the flange portion 51 is formed to have a plate shape so as to fit the upper surface of the stage 75; thus, the valve mounting surface 56 is orthogonal to the direction where 15 the punch 80 presses. In addition, the reference surface 73 is orthogonal to the direction where the measuring element 86 is lowered. By the reference surface 73 and the valve mounting surface 56 being formed as described above, the depth of the valve mounting surface 56 from the reference surface 73 can be obtained by one point in the reference surface 73 being measured. 20 [0056] Next, a method of forming the valve mounting mechanism 100 by riveting the discharge valve 57 and the valve retainer 58 on the valve mounting surface 56 of the flange portion 51 will be described. 25 [0057] The reference surface 73 and the valve mounting surface 56 are formed in the upper surface of the flange portion 51 by the upper surface of the flange portion 51 being cut with the same tool. [0058] 20 While the valve retainer 58 being layered on the discharge valve 57, the discharge valve 57 and the valve retainer 58 are arranged on the valve mounting surface 56 of the valve seat 55 being the first recessed portion of the flange portion. At this point, the discharge valve 57 and the valve retainer 58 are arranged on the 5 valve mounting surface 56 so that the first opening 70 of the valve retainer 58 and the second opening 71 of the discharge valve 57 overlap the rivet hole 54. [0059] Next, the rivet 16 is inserted into the rivet hole 54 from the lower surface of the flange portion 51. A portion of the rivet 16 protruding from the rivet hole 54 in the 10 upper surface of the flange portion 51 is then inserted into the first opening 70 of the discharge valve 57 and the second opening 71 of the valve retainer 58. Lastly, the top of the rivet 16 passing through the flange portion 51, through the discharge valve 57, and through the valve retainer 58 is squashed (swaged) by the punch 80 of the riveting machine 300, and the discharge valve 57 and the valve retainer 58 are fixed 15 to the valve seat 55 of the flange portion 51 with the rivet 16 (are riveted on the valve seat 55 with the rivet 16). Note that, for preventing the rivet 16 from coming out of the rivet hole 54, an end portion 16a of the rivet 16 near the lower surface of the flange portion 51 has a diameter larger than the diameter of the rivet hole 54 and has a shape protruding downward. 20 [0060] Fig. 10 is a schematic view of an example of the case in which the flange portion 51 is placed on the riveting machine 200, and the discharge valve 57 and the valve retainer 58 are fixed, with the rivet 16, to the flange portion 51 by using the riveting machine 200. Fig. 10 is a sectional view of the flange portion 51, the valve 25 mounting surface 56, the rivet 16, the discharge valve 57, and the valve retainer 58 that are cut in the direction traversing the center of each of the rivet hole 54 and the discharge hole 52 in the valve mounting surface 56. Fig. 11 is a schematic view of the example of the case in which the flange portion 51 is placed on the riveting machine 200, and the discharge valve 57 and the 30 valve retainer 58 are fixed, with the rivet 16, to the flange portion 51 by using the 21 riveting machine 200. In Fig. 11, the discharge valve 57 and the valve retainer 58 are disposed in the valve seat 55. As with Fig. 9, Fig. 10 is a sectional view of the flange portion 51, the reference surface 73, the valve mounting surface 56, the rivet 16, the discharge valve 57, and the valve retainer 58 that are cut in the direction 5 traversing the reference surface 73 and the valve mounting surface 56 from the central axis C of the bearing portion 51. [0061] As Fig. 10 and Fig. 11 illustrate, the riveting machine 200 includes the stage 75, a support body 76, the punch 80, a vertical-direction servomotor 81, a rotation10 direction servomotor 82, a discharge-valve-and-valve-retainer fixing jig 83, the measuring device 84, an adjustment knob 85, the measuring element 86, a controller 87, a determination unit 88, and a spring 89. [0062] When the upper bearing is placed on the stage 75 with the bearing portion 15 facing upward, the vertical-direction servomotor 81 supports the punch 80 so that the punch 80 can move in the direction parallel to a perpendicular to the upper surface of the stage 75, that is, in the thickness (depth) direction of the flange portion 51. The same applies to the lower bearing. The rotation-direction servomotor 82 supports the punch 80 so that the punch 80 can rotate. The vertical-direction servomotor 81, 20 the rotation-direction servomotor 82, and the measuring device 84 are fixed to the support body 76. The discharge-valve-and-valve-retainer fixing jig 83 is supported by the support body 76 with the spring 89 interposed therebetween. The support body 76 is fixed to a base 78 (not illustrated) below the stage 75 with a fixing portion 77 (not illustrated). The stage 75 can slide on the base 78 in the horizontal direction, 25 that is, in the direction perpendicular to the direction where the punch 80 moves. [0063] The measuring device 84 measures the position of a surface, with which the measuring element 86 comes into contact, from a surface of the stage 75 (the other side surface, that is, the lower surface of the flange portion 51) in the direction parallel 30 to a perpendicular to the upper surface of the stage 75, that is, in the thickness 22 (depth) direction of the flange portion 51. The measuring device 84 sends, to the determination unit 88, the position of the surface with which the measuring element 86 is in contact. [0064] 5 The determination unit 88 is provided with a storage unit 88a (not illustrated) and a calculation unit 88b (not illustrated), and the storage unit 88a stores a distance h1 between the reference surface 73 and the valve mounting surface 56 in the depth direction of the flange portion 51. With the position of the reference surface 73, measured by the measuring element 86, in relation to the surface of the stage 75 in 10 the thickness (depth) direction of the flange portion 51 as a reference value, the calculation unit 88b determines a lowering amount by which the punch 80 is lowered in the thickness (depth) direction of the flange portion 51 based on the distance h1 between the reference surface and the valve mounting surface in the depth direction of the flange portion 51, the distance h1 being read from the storage unit 88a. The 15 calculation unit 88b sends, to the controller 87, the lowering amount of the punch 80 in the thickness (depth) direction of the flange portion 51. [0065] The controller 87 controls the vertical-direction servomotor 81 and the punchrotation-direction servomotor 82 based on the lowering amount of the punch 80 in the 20 thickness (depth) direction of the flange portion 51, the lowering amount being sent from the calculation unit 88b. Due to such control of the controller 87 over the vertical-direction servomotor 81 and the punch-rotation-direction servomotor 82, the punch 80, while rotating, moves down, in the thickness (depth) direction of the flange portion 51, from the upper surface region of the flange portion 51 toward the valve 25 mounting surface 58 and pushes the rivet 16 to perform riveting. The verticaldirection servomotor 81 moves, other than the punch 80, the discharge-valve-andvalve-retainer fixing jig 83, the measuring device 84, the adjustment knob 85, and the measuring element 86 upward and downward in the direction parallel to a perpendicular to the upper surface of the stage 75. The discharge-valve-and-valve30 retainer fixing jig 83 is a jig for pushing the discharge valve 57 and the valve retainer 23 58 against the valve mounting surface 56 to temporarily fix the discharge valve 57 and the valve retainer 58. [0066] The discharge-valve-and-valve-retainer fixing jig 83 receives a spring force 5 exerted downward by the push spring 89 provided on the support body 76 mounted on the vertical-direction servomotor 81, thereby temporarily fixing the discharge valve 57 and the valve retainer 58 to the flange portion 51. The discharge-valve-and-valve-retainer fixing jig 83 is lowered in the direction parallel to a perpendicular to the upper surface of the stage 75 by the vertical10 direction servomotor 81, thereby coming into contact with the valve retainer 58, and the discharge-valve-and-valve-retainer fixing jig 83 being in contact with the valve retainer 58 is pushed toward the stage 75 by the vertical-direction servomotor 81. Thus, a gap can be suppressed from being left between the valve mounting surface 56 and the discharge valve 57 and between the discharge valve 57 and the valve 15 retainer 58. Riveting, by using the rivet 16, is performed while the discharge-valveand-valve-retainer fixing jig 83 prevents a gap from being left, and it is thereby possible to suppress a portion of the rivet 16 from being pushed into a space between the valve mounting surface 56 and the discharge valve 57 or a space between the discharge valve 57 and the valve retainer 58. 20 [0067] After the discharge valve 57 and the valve retainer 58 has temporarily been fixed to the flange portion 51, the punch 80 rotationally driven by the punch-rotationdirection servomotor 82 is caused to push downward by the vertical-direction servomotor 81. By the punch 80 coming into contact with the top portion of the rivet 25 16 and pressing, while rotating, the rivet 16 downward, the top portion of the rivet 16 is squashed to spread so as to be wider than the first opening 70 and the second opening 71, and the discharge valve 57 and the valve retainer 58 are thus fixed to the valve mounting surface 56. [0068] 24 As Fig. 7 and Fig. 8 illustrate, the measuring element 86 of the riveting machine 200 is lowered, in the direction parallel to a perpendicular to the upper surface of the stage 75, toward the reference surface 73 provided in the upper surface of the flange portion 52, and the measuring element 86 comes into contact with the reference 5 surface 73. The measuring element 86 measures the position (height) of the reference surface 73 from the upper surface of the stage 75 of the riveting machine 200. With the measured position of the reference surface 73 as the reference value, the position that is h1 lower than the reference value in the direction parallel to a 10 perpendicular to the upper surface of the stage 75 is considered to be the position (height) of the valve mounting surface 56. The calculation unit 88b calculates a value h2 by subtracting, from h1, the thickness of the discharge valve 57, the thickness of the valve retainer 58, and the reference value of the thickness of the processed head portion of the rivet on the 15 valve retainer 58. The controller 87 then operates the vertical-direction servomotor 31a so that the center of a recessed portion of the distal end of the punch 80 is lowered to the position that is h2 lower than the reference value. By the controller 87 controlling the punch 80 as described above, it is possible to mount the discharge valve 57 and the valve retainer 58 on the valve mounting surface 17b through riveting 20 in a stable manner irrespective of variation in the position of the valve mounting surface 17b from the bottom surface of the flange portion 51. Note that, although the measuring element 86 measures the position (height) of the reference surface 73 from the upper surface of the stage 75, this is not only an option, and the measuring element 86 is not required to measure the position of the reference surface 73 from 25 the upper surface of the stage 75 when the reference value can be set. [0069] Fig. 12 is a flowchart of a manufacturing method, of Embodiment 1, in which the discharge valve 57 and the valve retainer 58 are fixed to the flange portion 51 by a riveting method. Note that, in the following description, there will be described a 25 method of fixing the discharge valve 57 and the valve retainer 58 to the flange portion 51 of the upper bearing 50 of the compressor 1 by a riveting method. [0070] The reference surface 73 and the valve mounting surface 56 are formed in the 5 one-side surface of the flange portion, that is, the upper surface of the flange portion 51 by the upper surface of the flange portion 51 being cut with the same tool (step S1). [0071] The discharge valve 57 and the valve retainer 58 are arranged, while the valve 10 retainer 58 being layered on the discharge valve 57, on the valve mounting surface 56 that has been formed in the upper surface of the flange portion 51 through step S1 (step S2). The rivet 16 is inserted into the rivet hole 54 of the flange portion 51, into the first opening 71 of the discharge valve 57, and into the second opening 72 of the valve retainer 58, from the other side surface of the flange portion 51, that is, the 15 underside of the flange portion 51 (step S3). The flange portion 51 is placed on the stage 75 of the riveting machine 300 with the valve mounting surface 56 facing upward, and the work is thus put in the riveting machine 300 (step S4). [0072] When the flange portion 51 has been put in the riveting machine 300 through 20 step S4, the riveting machine 300 checks the flange portion 51 with a sensor (not illustrated). When the riveting machine 300 has checked the flange portion 51 with the sensor, the flange portion 51 is carried inside the riveting machine 300 (work determination, step S5). [0073] 25 When such carrying of the flange portion 51 inside the riveting machine 300 is completed through step S5, the vertical-direction servomotor 81 and the punchrotation-direction servomotor 82 of the riveting machine 300 go into action (step S6). [0074] 26 The vertical-direction servomotor 81 that has gone into action through step S6 lowers the measuring element 86, and the measuring element 86 comes into contact with the reference surface 73 of the flange portion 51 (step S7). [0075] 5 When the measuring element 86 that has been lowered to come into contact with the reference surface of the flange portion 51 through step S7, the determination unit 88 of the riveting machine 300 makes the zero-setting of the measuring element 86 so that the value of the height of the measuring element 86 that has been in contact with the reference surface 73 is set to zero. The reference surface 73 and 10 the valve mounting surface 56 are formed with a tool such as an end mill in advance so that the difference h1 in depth between the reference surface 73 and the valve mounting surface 56 has a constant value, and it is thereby possible to set the pushin depth of the punch 80 appropriate for the riveting at the valve seat 56 due to the zero-setting of the measuring element 86 (step S8). 15 [0076] The push-in depth of the punch 80 that has been set through step S8 is transmitted to the controller 87. When the push-in depth of the punch 80 appropriate for the riveting has been transmitted to the controller 87, the controller 87 drives the vertical-direction servomotor 81. The vertical-direction servomotor 81 lowers the 20 punch 80 toward the valve mounting surface 56 and pushes the punch 80 into the valve seat until the punch 80 reaches the push-in depth transmitted to the controller 87 (step S9). [0077] When the push-in depth of the punch 80 has reached the push-in depth 25 transmitted to the determination unit 88 through step S9, a signal is sent from the determination unit 88 to the controller 87, the controller 87 stops the lowering of thevertical-direction servomotor 31, and the push-in operation of the punch 80 is completed (step S10). At this time, the punch 80 presses and deforms the top portion of the rivet, and the valve retainer 58 and the discharge valve 57 are mounted 30 (riveted) on the valve mounting surface 56 with such deformed rivet. 27 [0078] When the lowering of the vertical-direction servomotor 31 has stopped to complete the push-in operation of the punch 80 through step S10, the controller 87 outputs a signal, and the return to the origin of the punch 80 is performed (step S11). 5 [0079] After the punch has returned to the origin thereof through step S11, the compressor-use valve mounting mechanism 200 in which the valve retainer 58 and the discharge valve 57 have been riveted is carried out to be taken out (step 12). [0080] 10 The push-in depth of the punch 80 can appropriately be changed with the adjustment knob 85 provided in the riveting machine 300. When the model of the upper bearing 5 and the lower bearing 8 is changed or when the fine adjustment in push-in depth of the punch 80 is required, the depth is set with the adjustment knob 85. 15 [0081] In the present example, the measuring element 86 measures the depth of the reference surface 73 of the flange portion 51, a push-in depth of the punch 80 appropriate for the riveting is set based on the fact that the difference in depth between the reference surface 73 and the valve mounting surface 56 is h21, and 20 riveting is performed; however, the riveting method of the present disclosure is not limited thereto. The riveting method may involve the following process. The discharge valve 57 and the valve retainer 58 are inserted into the valve seat 55, the depth of the upper surface of the valve retainer 58 is measured by the measuring element 86, the measured depth of the upper surface of the valve retainer 58 is then 25 sent to the controller 87, and the vertical-direction servomotor 81 is pushed in until reaching the measured depth of the upper surface of the valve retainer 58 to perform riveting. [0082] Although the vertical-direction servomotor 81 serving as a motor for lowering 30 the punch 80, the measuring device 84, the adjustment knob 85, the measuring 28 element 86, and the discharge-valve-and-valve-retainer fixing jig 83 is used in Embodiment 1, the riveting method of the present disclosure is not limited thereto. The mechanism for lowering the punch 80, the measuring device 84, the adjustment knob 85, the measuring element 86, and the discharge-valve-and-valve-retainer fixing 5 jig 83 may have any device form, and the mechanism may be pneumatic or hydraulic or may be of the cylinder type. In addition, although the measuring element 86 is a contact measuring element in Embodiment 1, the measuring element 86 of the present disclosure is not limited thereto and may be a noncontact measuring element. 10 [0083] Fig. 13 is a schematic view of a manufacturing apparatus 300, according to Embodiment 1, for manufacturing the valve mounting mechanism 100 of the compressor 1. [0084] 15 As Fig. 13 illustrates, the manufacturing apparatus 300 includes a pallet 90. The pallet 90 includes four stations, that is, a first station 90a, a second station 90b, a third station 90c, and a fourth station 90d. Hereinafter, the process of riveting the discharge valve 57 and the valve retainer 58 on the upper bearing by using the manufacturing apparatus 300 will be described. When the upper bearing 50 has 20 been carried in the first station 90a with the bearing portion facing upward, the pallet 90 is rotated by 90 degrees, and the upper bearing 50 moves to the position of the second station 90b. At the position of the second station 90b, an arm 91, which is not illustrated, places the discharge valve 57 and the valve retainer 58 on the valve mounting surface 56 in the valve seat 55 formed in the upper surface of the flange 25 portion 51. When the discharge valve 57 and the valve retainer 58 has been placed on the valve mounting surface 56, the pallet 90 is rotated by 90 degrees from the position of the second station 50b, and the upper bearing 50 moves to the position of the third station 90c. The riveting machine 300 illustrated in Fig. 7 and Fig. 8 is disposed at the position of the third station 90c and rivets the discharge valve 57 and 29 the valve retainer 58 on the valve mounting surface 56 of the flange portion 51 at the third station 90c. [0085] The flowchart in Fig. 12 illustrates the control of the riveting machine 300 5 during riveting. [0086] When the discharge valve 57 and the valve retainer 58 have been riveted on the valve mounting surface 56, the pallet 90 is rotated by 90 degrees from the position of the third station 90c, and the upper bearing 50 moves to the position of the fourth 10 station 90d. At the position of the fourth station 90d, the following points are checked by the height from the underside of the flange portion 51 to the reference surface 73 and the height from the underside of the flange portion 51 to the upper surface of the valve retainer 58 being measured. It is checked that there is no gap between the valve mounting surface 56 and the discharge valve 57 and between the 15 discharge valve 57 and the valve retainer 58, whether the discharge valve 57 or the valve retainer 58 is mounted diagonally relative to the valve mounting surface 56, or whether plural discharge valves 57 or plural valve retainers 58 are mounted. By using the reference surface 73 in such a way, it is also possible to check whether the quality of riveting is good or poor. 20 [0087] Although the method in which the pallet 90 performs riveting at the four stations between the first station 50a and the fourth station 50d is described in the present example, the number of stations of the pallet 90 of the present disclosure is not limited thereto. 25 If the measuring element 86 or other tools can measure the depth of the reference surface 73 before the discharge valve 57 and the valve retainer 58 are riveted on the valve mounting surface 56, the insertion method of each of the discharge valve 57, the valve retainer 58, and the rivet 16 can be modified variously. Moreover, another processing can be performed between the processes such as 30 measuring of the reference surface 73 and riveting of the discharge valve 57 and the valve retainer 58 on the valve mounting surface 56. [0088] In addition, although, in the present example, the rotation direction of the pallet 5 90 is the counterclockwise direction, the rotation direction of the pallet 90 of the present disclosure is not limited thereto and may alternatively be the clockwise direction. [0089] Although, in the present example, the pallet 90 is of the rotary type, the shape 10 of the pallet 90 of the present disclosure is not limited thereto and may be a lineartype pallet (not illustrated) as long as the measuring element 86 can measure the distance of the reference surface 73 from the stage 75 (the thickness from the underside of the flange portion 51 to the reference surface 73) before the discharge valve 57 and the valve retainer 58 are riveted on the valve mounting surface 56. 15 [0090] In an exiting method, whether riveting is inadequate is determined as follows. After the discharge valve and the valve retainer are riveted on the flange portion, the outside diameter or the height of the rivet head of the rivet (a top portion of the rivet that has been squashed by being pushed by the punch of the riveting machine) is 20 measured with a measuring tool such as a vernier caliper, or the shape of the rivet head is visually determined. However, in such a method, outflow of a defective can be prevented but a defective cannot be prevented from being generated. Moreover, in the existing method, it takes some time, in manufacturing, to determine, one by one, the shapes of the rivet heads that have been swaged through visual inspection 25 or with a measuring tool. In Embodiment 1, the measuring element 86 of the single riveting machine 200 measures the distance of the reference surface 73 from the stage 75 (the thickness from the underside of the flange portion 51 to the reference surface 73), and the push-in depth of the punch 80 is determined based on the data in the storage unit 88a 30 that stores a predetermined distance from the valve mounting surface 56 to the 31 reference surface 73 in the thickness (depth) direction of the flange portion 51. By using such a manufacturing method, it is possible to suppress inadequate riveting from being caused when the discharge valve 57 and the valve retainer 58 are riveted on the upper surface of the flange portion 51. In addition, due to the unnecessity of 5 measurement regarding the rivet head in Embodiment 1, manufacturing processes for the valve mounting mechanism 100 of the compressor 1 can be reduced, and the efficiency in manufacturing can be improved. [0091] Furthermore, there has been known a method by which inadequate riveting is 10 suppressed by variation in the thickness of the flange portion being detected through a measurement inspection and by a bearing that does not meet established standards regarding variation in thickness being removed from the manufacturing process. However, in this existing method, the process of the measurement inspection of the thickness of the flange portion is required to be added, and there arises a problem of 15 increase in the number of processes. In addition, because variation in the thickness of the flange portion is unexpectedly caused, there arises a problem that such unexpected variation cannot be handled. In Embodiment 1, the measuring element 86 measures the distance (the position in the thickness (depth) direction of the flange portion 51) of the reference 20 surface 73 to the upper surface of the stage 75 in the direction parallel to a perpendicular to the upper surface of the stage 75, and the push-in depth of the punch 80 is determined based on the data in the storage unit 88a that stores the distance of the reference surface 73 to the valve mounting surface 56 in the thickness (depth) direction of the flange portion 51. By using such a manufacturing method, 25 even if variation in the thickness of the flange portion 51 is unexpectedly caused, it is possible to perform riveting in a stable manner and to suppress inadequate riveting from being caused. In addition, there is no need to measure the thickness of the flange portion 51 for suppressing inadequate riveting in Embodiment 1, and it is thereby possible to reduce manufacturing processes for the valve mounting 30 mechanism 100 of the compressor 1 and to improve the efficiency in manufacturing. 32 Reference Signs List [0092] 1: compressor, 2: accumulator, 10: sealed container, 16: rivet, 20: motor, 30: shaft, 40: cylinder, 50: lower bearing, 60: lower bearing, 31: eccentric shaft portion, 5 32: eccentric ring, 51: flange portion, 52: discharge hole, 53: bearing portion, 54: rivet hole, 55: valve seat, 56: valve mounting surface, 57: discharge valve, 58: valve retainer, 59: opening and closing portion, 70: first opening, 71: second opening, 72: reference-surface machined hole, 73: reference surface, 100: valve mounting mechanism, 200: riveting machine, 75: stage, 80: punch, 81: vertical-direction 10 servomotor, 82: punch-rotation-direction servomotor, 83: discharge-valve-and-valveretainer fixing jig, 84: measuring device, 85: adjustment knob, 86: measuring element, 87: controller, 88: determination unit, 89: push spring, 300: manufacturing apparatus 33 We Claim: [Claim 1] A manufacturing method of a discharge valve mechanism in which, on a flange portion having a discharge hole and a rivet hole, of a compressor, a discharge valve 5 that has a first opening and covers the discharge hole and a valve retainer that has a second opening and regulates deformation of the discharge valve are mounted with a rivet inserted into the rivet hole, the manufacturing method comprising: forming a first recessed portion having a valve mounting surface and a second recessed portion having a reference surface in a one-side surface of the flange 10 portion with a same tool so that the valve mounting surface is at a predetermined distance to the reference surface in a thickness direction of the flange portion; placing the discharge valve and the valve retainer on the valve mounting surface; inserting the rivet into the rivet hole formed in the valve mounting surface, into 15 the first opening of the discharge valve, and into the second opening of the valve retainer from an other side surface of the flange portion; measuring a position of the reference surface in relation to the other side surface of the flange portion; and fixing the discharge valve and the valve retainer to the valve mounting surface 20 by the rivet being deformed by being pressed by a punch from the one-side surface, based on a distance h1 of the valve mounting surface to the reference surface in a depth direction, a thickness of a discharge valve, and a thickness of a valve retainer. [Claim 2] The manufacturing method of a discharge valve mechanism of claim 1, 25 wherein a shape of the second recessed portion is a circle, wherein the first recessed portion has a region extending linearly, and wherein a diameter of the circle of the second recessed portion is as large as a width of the region. [Claim 3] 34 The manufacturing method of a discharge valve mechanism of claim 1 or claim 2, wherein the valve mounting surface and the reference surface are formed so as to be parallel to one another. 5 [Claim 4] The manufacturing method of a discharge valve mechanism of any one of claims 1 to 3, wherein the valve mounting surface is formed so as to be orthogonal to a direction where the punch presses. 10 [Claim 5] A compressor-use bearing comprising a discharge valve mechanism manufactured by the manufacturing method of any one of claims 1 to 4. [Claim 6] 15 A compressor comprising the compressor-use bearing of claim 5. [Claim 7] A compressor-use discharge valve mechanism comprising: a flange portion that has, in a one-side surface, a first recessed portion having 20 a valve mounting surface formed linearly and has a second recessed portion having a reference surface; a discharge valve that is disposed on the valve mounting surface and opens and closes a discharge hole formed in the first recessed portion; and the valve retainer that is disposed so as to be layered on the discharge valve 25 and regulates elastic deformation of the discharge valve, wherein the discharge valve and the valve retainer are mounted on the valve mounting surface with a rivet, wherein a shape of the second recessed portion is a circle, wherein the first recessed portion has a region extending linearly, and 35 wherein a diameter of the circle of the second recessed portion is as large as a width of the region. [Claim 8] The compressor-use discharge valve mechanism of claim 7, 5 wherein the valve mounting surface and the reference surface are parallel to one another. [Claim 9] A compressor comprising the compressor-use discharge valve mechanism of claim 7 or claim 8.