Description:1. Technical Field
[0001] The present invention relates to an automatic tube expanding apparatus and an automatic tube expanding method.

2. Description of the Background
[0002] A conventional automatic tube expanding device includes an expanding device including an expander having a mandrel and a frame member, a rotary drive machine for rotationally driving the mandrel, a clamp device for clamping the frame member, and a moving device for moving the clamp device in an axial direction of the expander; and a robot for supporting and moving the expanding device (JP-A-2020-138213; hereinafter, Patent Literature 1).

BRIEF SUMMARY
[0003] The mandrel to which the frame member is externally fitted moves (advances by itself) toward the distal end by the feed angle action of the roller rotatably held by the frame member while rotating. The robot described in Patent Literature 1 has a function (hereinafter, referred to as a following function) of causing a robot to move the expander in a direction of an axial external force while the expander receives the axial external force, thereby causing a support position of the expanding device by the robot to follow an axial movement of the expander. However, in general, the robot does not have a following function. In order to implement Patent Literature 1, it is necessary to add a following function to the robot.
[0004] An object of the present invention is to provide an automatic tube expanding apparatus and an automatic tube expanding method that can efficiently perform a tube expanding operation using a general purpose robot.
[0005] In order to solve the above problems, a first aspect of the present invention provides an automatic tube expanding apparatus, including:
a tube expanding device configured to perform a tube expanding process; and
a robot configured to support and move the tube expanding device; wherein
the tube expanding device includes,
an expander including,
a mandrel,
a collar member slidably supported by the mandrel,
a cylindrical frame rotatably supported inside the collar member, and
a plurality of rollers rotatably held by the frame,
a rotary drive machine configured to rotationally drive the mandrel,
a clamp device configured to clamp the collar member,
a clamp moving device configured to move the clamp device in an axial direction of the expander, and
a feeding device configured to move the mandrel in the axial direction of the expander.
[0006] A second aspect of the present invention provides an automatic tube expanding method, including:
moving, by a clamp moving device, a frame member having a frame by which a roller is rotatably held toward a distal end of a mandrel to which the frame member is externally fitted;
clamping the frame member by a clamp device;
inserting the frame member and the mandrel into a tube by a robot;
stopping the robot when the frame member and the mandrel reaches a predetermined position;
feeding, by a feeding device, the mandrel rotating in a first direction by a rotary drive machine toward a distal end;
rotating the frame in the first direction to advance the mandrel toward a distal end by itself;
expanding the tube by the roller;
temporarily stopping a rotation of the mandrel by the rotary drive machine when a load torque of the rotary drive machine reaches a predetermined set torque;
rotating, by the rotary drive machine, the mandrel in a second direction that is a reverse direction of the first direction to cause the frame to rotate in the second direction for the mandrel to retract toward a basal end by itself;
pulling the mandrel rotating in the second direction toward a basal end by the feeding device; and
pulling, by the robot, the frame member and the mandrel from the tube.
[0007] According to the present invention, it is possible to provide an automatic tube expanding apparatus and an automatic tube expanding method capable of efficiently performing a tube expanding operation using a general purpose robot.

BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a schematic perspective view of an automatic tube expanding apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic block diagram showing a control configuration of the automatic tube expanding apparatus according to the present embodiment together with a cross-sectional view of the expander.
FIG. 3 is a diagram schematically showing an inclination of a roller.
FIG. 4 is a flowchart showing the contents of the automatic tube expanding method.
FIG. 5 is a schematic side view for explaining the operation during the tube expanding operation of the automatic tube expanding apparatus.
FIG. 6 is a schematic side view for explaining the operation during the tube expanding operation of the automatic tube expanding apparatus continuing from FIG. 5.

DETAILED DESCRIPTION
[0009] Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
In the drawings, common components are denoted by the same reference numerals, and redundant descriptions thereof will be omitted as appropriate.
[0010] An automatic tube expanding apparatus 1 according to an embodiment of the present invention will be described in detail with reference to FIGs. 1 to 6 as appropriate.
[0011] As shown in FIGs. 1 and 2, the automatic tube expanding apparatus 1 of the present embodiment includes a tube expanding device 3, a robot 2, and a control device 10.
[0012] The tube expanding device 3 performs the tube expanding operation of the tube T (see FIG. 5A and the like, hereinafter). The tube expanding device 3 joints the tube T, which constitutes a heat exchanger, and the tube plate TB to which the tube T is attached (see FIG. 5A and the like, hereinafter) by press-contact fixing the tube T to an inner surface of a mounting hole TBa (see FIG. 5A and the like, hereinafter) formed in the tube plate TB by expanding the outer diameter of the tube T with an expander 4. The robot 2 is, for example, a vertical articulated robot, a horizontal articulated robot, an orthogonal axis robot, or a parallel link robot. The robot 2 supports and moves the expanding device 3. The expanding device 3 is fixed to a distal end portion of an arm 21 of the robot 2. The control device 10 is a computer that controls the operation of each unit of the automatic tube expanding device 1 by executing a program stored in advance in the storage unit by CPU.
[0013] The expanding device 3 includes the expander 4, a rotary drive machine 6, a clamp device 7, a clamp moving device 8, a feeding device 5, and a coupling 9.
[0014] The expander 4 includes a mandrel 41, a cylindrical frame member 42, and a plurality of rollers 43. The mandrel 41 has, on an outer peripheral surface, a tapered portion 411 having a smaller diameter toward a distal end. The frame member 42 is slidably and rotatably externally fitted to the mandrel 41. The plurality of rollers 43 are rotatably held by the frame member 42.
[0015] The mandrel 41 includes the tapered portion 411 located on the distal end (hereinafter, also referred to as a "front side") of the mandrel 41, and a cylindrical portion 412 having a cylindrical shape located on a basal end (hereinafter, also referred to as a "rear side") of the tapered portion 411. A cap nut 413 is fixed to a distal end of the mandrel 41 by screw fastening. Further, a square shank (not shown) is provided at a rear end of the mandrel 41. The square shank of the mandrel 41 is connected to a rotary shaft 61 of the rotary drive machine 6 via the coupling 9.
[0016] The frame member 42 includes a cylindrical frame 44 that rotatably holds the roller 43, and an annular collar 45 attached to an outer peripheral surface of the frame 44. The collar 45 includes a collar rear wheel 451 fixed to an outer peripheral surface of the frame 44, and a collar front wheel (collar member) 453 rotatably disposed on a front side (a front end of the expander 4) with respect to the collar rear wheel 451 via a ball retainer 452. That is, the collar front wheel 453 is slidably supported by the mandrel 41, and the frame 44 is rotatably supported inside the collar front wheel 453.
[0017] The frame 44 has a hollow portion having an inner diameter slightly larger than an outer diameter of the cylindrical portion 412 of the mandrel 41. The mandrel 41 is inserted through the hollow portion of the cylindrical frame 44. A plurality of elongated roller grooves 421 are formed on the distal end portion of the frame 44 at intervals of 120 degrees, for example, in the circumferential direction. Each roller groove 421 is positioned at the same position with respect to the longitudinal direction of the frame 44. The roller 43 having a truncated cone shape is engaged and held in the roller groove 421. The roller 43 is partially exposed from the roller groove 421 to the radially outside and inside of the frame 44.
[0018] The frame 44 has a male screw formed on the outer peripheral surface of the rear end portion with a smaller outer diameter. The collar rear wheel 451 having a female screw on the inner peripheral surface is screwed into the male screw. The collar rear wheel 451 is fixed to the frame 44 with a lock nut 454. Note that the means of fixing the collar rear wheel 451 to the frame 44 may be a means using, for example, a hexagonal socket set screw instead of the means using the lock nut 454. With the ball retainer 452 disposed on the front surface of the collar rear wheels 451 and the collar front wheels 453 disposed on the front surface of the ball retainer 452, the collar front wheels 453 and the collar rear wheels 451 are axially integrated by a retaining ring 455 to form the collar 45.
[0019] The side surface of the roller 43 comes into contact with the outer peripheral surface of the tapered portion 411 of the mandrel 41 at the radially inside of the frame 44 while rotating about the longitudinal central axis thereof. On the other hand, at the radially outside of the frame 44, substantially opposite side of the roller 43 to the contact portion with the mandrel 41 comes into contact with the inner peripheral surface of the tube T to be expanded while rotating about the longitudinal central axis at the time of expanding.
[0020] As shown in FIG. 3, the center axis of the roller 43 is inclined by a predetermined angle θ with respect to the axial direction of the frame member 42 (the same as the axial direction of the mandrel 41). The roller 43 has a truncated conical shape having a taper in which the direction of the tapered portion 411 of the mandrel 41 is opposite to the taper and the inclination is half.
[0021] As shown in FIG. 2, the cap nut 413 has, at the rear end portion, a tapered surface 416 having a small diameter toward the rear side. In this configuration, the front end of the frame 44 abuts the tapered surface 416 when the frame member 42 is moved forward to minimize the tool diameter. The center axis of the frame member 42 is thus aligned with the center axis of the mandrel 41. The sagging of the distal end of the mandrel 41 due to its own weight can thus be suppressed, and the insertability of the expander 4 into the tube T is improved. Here, the tool diameter refers to the diameter of the expanding process by the expander 4, and means the diameter of a circumscribed circle formed by an envelope circumscribing the plurality of rollers 43.
[0022] The rotary drive machine 6 rotationally drives the mandrel 41 of the expander 4 via the coupling 9. Here, a servo motor is used as the rotary drive machine 6.
[0023] The clamp device 7 clamps the frame member 42 of the expander 4, in particular the collar front wheels 453 (see FIG. 2) of the frame member 42. The clamp device 7 includes a pair of claws 71, an air chuck 72, and a support plate 73 that supports the air chuck 72. The pair of claws 71 hold and clamp the frame member 42 of the expander 4 from both sides in the radial direction. The air chuck 72 includes an air cylinder. The air chuck 72 moves the pair of claws 71 forward and backward with respect to the frame member 42 of the expander 4 by air pressure. The air chuck 72 is fixed to the front surface of the support plate 73. The support plate 73 has a rectangular plate shape (see FIG. 1).
[0024] As shown in FIG. 2, the claw 71 includes a claw main body 711 and a claw support portion 712 that supports the claw main body 711. The claw 71 has an L-shaped cross section. The claw main body 711 has an arcuate surface 713 that contacts the outer circumferential surface of the collar front wheel 453 of the frame member 42. The claw support portion 712 includes a receiving portion 714 and an abutment portion 715. The receiving portion 714 is disposed on the rear side of the claw support portion 712. The receiving portion 714 has an arcuate surface having an inner diameter smaller than an outer diameter of the collar front wheel 453. The receiving portion 714 receives the collar rear wheel 451 and the lock nut 454 to pass through. The abutment portion 715 is disposed on a front surface of the claw support portion 712. The abutment portion 715 abuts the collar front wheel 453 of the frame member 42 in the axial direction of the expander 4.
[0025] The clamp moving device 8 moves the clamp device 7 in the axial direction of the expander 4. The clamp moving device 8 is fixed to a casing 62 of the rotary drive machine 6. An air cylinder is used here as the clamp moving device 8, but an electric cylinder, for example, may be used.
[0026] The clamp moving device 8 includes a cylinder body 81, a piston 821, and a piston rod 822. The cylinder body 81 generates a driving force by compressed air supplied into the cylinder body 81. The piston 821 is slidably disposed in the cylinder body 81. The piston rod 822 has a basal end fixed to the piston 821, and a distal end protruding toward outside of the cylinder body 81. A first chamber 811 and a second chamber 812 are formed in the cylinder body 81 with the piston 821 interposed therebetween. The first chamber 811 and the second chamber 812 are connected to a compressed air source 31 via a throttle 35 and a channel switching valve 33, respectively. The flow rate of the compressed air is adjusted by the throttle 35. The channel switching valve 33 switches the supply destination of the compressed air.
[0027] When the compressed air is supplied to the first chamber 811, the piston rod 822 advances, and when the compressed air is supplied to the second chamber 812, the piston rod 822 retracts. The distal end of the piston rod 822 is connected to the clamp device 7. Specifically, the distal end of the piston rod 822 is fixed to the support plate 73 of the clamp device 7. A guide rod 83 may be disposed on the support plate 73. The guide rod 83 is slidably inserted into a guide bush 84 provided in the clamp moving device 8. Thus, the clamp moving device 8 can smoothly move the clamp device 7.
[0028] A position sensor 85 is disposed on the cylinder body 81. The position sensor 85 detects the position of the piston 821. The position sensor 85 is, for example, a linear scale.
[0029] The feeding device 5 moves the mandrel 41 of the expander 4 in the axial direction of the expander 4. The feeding device 5 of the present embodiment is disposed between the distal end portion of the arm 21 of the robot 2 and the rotary drive machine 6, and moves the mandrel 41 together with the rotary drive machine 6 and the coupling 9.
[0030] The feeding device 5 includes a feed cylinder 51, a piston 521, a piston rod 522, a linear motion guide 53, and a base plate 54. The feed cylinder 51 generates a driving force by the compressed air supplied into the feed cylinder 51. The feed cylinder 51 is connected to the casing 62 of the rotary drive machine 6. The piston 521 is slidably disposed in the feed cylinder 51. The basal end of the piston rod 522 is fixed to the piston 521. The distal end of the piston rod 522 extends and protrudes from the feed cylinder 51. A first chamber 511 and a second chamber 512 are formed in the feed cylinder 51 with the piston 521 interposed therebetween. The first chamber 511 and the second chamber 512 are connected to the compressed air source 31 via a throttle 34 and a channel switching valve 32, respectively. The flow rate of the compressed air is adjusted by the throttle 34. The channel switching valve 32 switches the supply destination of the compressed air.
[0031] The base plate 54 has a support portion 55. The base plate 54 is fixed to a distal end portion of the arm 21 of the robot 2. The linear motion guide 53 is disposed on the base plate 54 and extends along the axial direction of the expander 4. The feed cylinder 51 is disposed on the linear motion guide 53. The feed cylinder 51 is guided by the linear motion guide 53 to reciprocate with respect to the base plate 54. The distal end of the piston rod 522 is connected to the support portion 55 provided at an end portion of the base plate 54.
[0032] When the compressed air is supplied to the first chamber 511, the piston rod 522 is extended to move the feed cylinder 51 forward. Then, as the feed cylinder 51 moves forward, the mandrel 41 moves forward together with the rotary drive machine 6 and the coupling 9. On the other hand, when the compressed air is supplied to the second chamber 512, the piston rod 522 is retracted to move the feed cylinder 51 rearward. As the feed cylinder 51 moves rearward, the mandrel 41 moves rearward together with the rotary drive machine 6 and the coupling 9.
[0033] The control device 10, which is connected to the position sensor 85, receives a signal from the position sensor 85. Further, the control device 10 is connected to the rotary drive machine 6 and the channel switching valves 32, 33, to control these operations.
[0034] Next, the operation of the automatic tube expanding apparatus 1 of the present embodiment will be described. The operation of the automatic tube expanding device 1 is controlled by the control device 10.
With reference to FIGs. 4 to 6, an automatic tube expanding method for performing a tube expanding operation using the automatic tube expanding apparatus 1 will be described.
[0035] First, the robot 2 moves the expander 4 of the expanding device 3 to a position facing the end face of the tube T to be expanded. The position of the tube T to be expanded can be specified by using the position data (design data) of the mounting hole TBa of the tube plate TB or by using the image of the mounting hole TBa of the tube plate TB and performing image processing.
[0036] As shown in FIG. 4, the clamp device 7 unclamps the frame member 42 in S1. Subsequently, the rotary drive machine 6 starts a rotation operation (forward rotation) in S2. Note that the starting time of the rotation operation of the rotary drive machine 6 may be appropriately changed as long as it is before the step S5 described later.
[0037] Subsequently, the clamp moving device 8 moves the clamp device 7 toward the axial distal end. At this time, the clamp moving device 8 moves (advances) the frame member 42 toward the distal end of the mandrel 41 while the abutment portion 715 of the clamp device 7 is in contact with the collar front wheel 453 of the frame member 42 in S3. The roller 43 is thus positioned on the small diameter side of the tapered portion 411 of the mandrel 41, and the amount of protrusion of the roller 43 radially outward is the smallest. That is, the tool diameter is minimized.
[0038] Subsequently, the clamp device 7 clamps the collar front wheels 453 of the frame member 42 in S4 (see FIG. 5A). Then, the holding force of the clamp moving device 8 with respect to the axial position of the clamp device 7 is released. Specifically, the clamp moving device 8 is in a brake release state, that is, in a floating state that moves following an external force.
[0039] Subsequently, the robot 2 inserts the expander 4 of the expanding device 3 into the tube T in S5.
[0040] Subsequently, it is determined whether or not the front end face of the collar front wheel 453 of the frame member 42 contacts the end face of the tube T, that is, whether or not the collar front wheel 453 abuts against the tube T is detected in S6. Here, a position sensor 85 monitors the position of the piston 821. When the collar front wheel 453 abuts against the tube T while the robot 2 advances the tube expanding device 3, the position of the piston 821 is pushed back relative to the cylinder body 81. When the position sensor 85 detects that the piston 821 is pushed back, the control device 10 determines that the collar front wheel 453 abuts against the tube T. Note that the frame member 42 and the mandrel 41 have reached a predetermined position programmed in advance may be detected.
[0041] When the abutment of the collar front wheel 453 with the tube T is not detected (No in S6), the expander 4 is continuously inserted into the tube T by the robot 2.
On the other hand, when the abutment of the collar front wheel 453 with the tube T is detected (Yes in S6, see FIG. 5B), the robot 2 is stopped in S7. That is, the distal end position of the arm 21 of the robot 2 is kept. That is, the robot 2 holds the position of the base plate 54 against the external force in the servo-on state.
[0042] At the same time as or immediately after the robot 2 is stopped, the feeding device 5 operates to move the feed cylinder 51 forward in S8 (see FIG. 5C). Here, as the feed cylinder 51 advances, the mandrel 41 advances together with the rotary drive machine 6 and the coupling 9. As a result, the tube expanding process is performed.
[0043] During the expanding process, the collar front wheel 453 of the collar 45 contacts the end face of the tube T and neither rotates nor moves axially. However, as the mandrel 41 is rotationally driven, the rotation of the mandrel 41 causes the roller 43 to revolve together with the frame 44 while rotating on the inner peripheral surface of the tube T. The roller 43 does not move in the axial direction. The frame 44 revolves around its own central axis as the roller 43 rotates. The frame 44 does not move in the axial direction.
On the other hand, as a feed angle is provided in which the central axis of the mandrel 41 and the central axis of the roller 43 are inclined by a predetermined angle θ, the mandrel 41 is naturally fed in the axial direction when rotated. The mandrel 41 thus moves toward the distal end by the action of the feed angle of the roller 43 while rotating. That is, the mandrel 41 advances by itself. This forward movement of the mandrel 41 moves the contact position between the roller 43 and the mandrel 41 toward the large diameter side of the tapered portion 411. Then, the tool diameter (the diameter of the contact surface between the roller 43 and the tube T) increases, and the tube T receives the tube expanding process.
[0044] While the mandrel 41 receives an axial external force for advancing by itself, the compressed air source 31 supplies compressed air to the first chamber 511. Then, the air in the second chamber 512 is exhausted. Then, the feeding device 5 advances the expander 4. That is, the feeding device 5 moves the mandrel 41 in the direction of the axial external force. As the air is a compressible fluid, the position of the mandrel 41 follows the axial movement of the mandrel 41 by advancing itself.
[0045] As described above, the mandrel 41 of the expander 4 receives the axial external force in a direction in which the expander 4 advances itself (self-advanced) during the expanding process, and the mandrel 41 receives the axial external force in a direction in which the expander 4 is pulled out by itself (self-retracted) even when the expander 4 is pulled out after the expanding process. In order to prevent the axial external force and the driving force of the feeding device 5 from pressing against each other, the feeding device 5 is driven by compressed air having a relatively small pressure so as to follow a load that is the axial external force.
[0046] Subsequently, the control device 10 determines whether or not a load torque of the rotary drive machine 6 has reached a predetermined set torque in S9. The load torque is obtained based on a current value flowing through the rotary drive machine 6.
[0047] When the load torque of the rotary drive machine 6 has not reached the set torque (No in S9), the tube expanding process is continued.
On the other hand, when the load torque of the rotary drive machine 6 reaches the set torque (Yes in S9), the rotary drive machine 6 stops rotating and reversely rotates in S10.
[0048] Simultaneously with the reverse rotation of the rotary drive machine 6, the feeding device 5 operates to retract the feed cylinder 51 in S11. Here, as the feed cylinder 51 is retracted, the mandrel 41 is retracted together with the rotary drive machine 6 and the coupling 9. That is, the feeding device 5 pulls back the reversely rotating mandrel 41 to the basal end. The mandrel 41 moves toward basal end, i.e., retracts by itself, by the action of the feed angle of the roller 43 while being reversely rotated. The retraction of the mandrel 41 moves the contact position of the roller 43 with the mandrel 41 toward the small diameter side of the tapered portion 411, so that the tool diameter is reduced.
[0049] While the mandrel 41 receives the axial external force that cause the mandrel 41 to retract by itself, the compressed air source 31 supplies compressed air to the second chamber 512. Then, the air in the first chamber 511 is exhausted. The feeding device 5 retracts the mandrel 41. That is, the feeding device 5 moves the mandrel 41 in the direction of the axial external force. Thus, the position of the mandrel 41 follows the axial movement of the mandrel 41 due to self-retraction. The feeding device 5 retracts the mandrel 41 to the retracted end.
[0050] In the step S8 or the step S11, the driving air may be exhausted from the feeding device 5. Specifically, the first chamber 511 and the second chamber 512 are connected to the atmosphere. In this case, as the piston 521 is freely movable by the external force, the piston 52 advances or retracts as the mandrel 41 advances or retracts by itself.
[0051] Subsequently, the robot 2 pulls out the expander 4 of the tube expanding device 3 from the tube T in S12 (see FIG. 6B), and the rotary drive machine 6 stops rotating.
[0052] As described above, the automatic tube expanding apparatus 1 according to the present embodiment includes the tube expanding device 3 that performs the tube expanding process of the tube T, and the robot 2 that supports and moves the tube expanding device 3. The expanding device 3 includes the expander 4, the rotary drive machine 6, the clamp device 7, the clamp moving device 8, and the feeding device 5. The expander 4 includes the mandrel 41, the collar front wheel (collar member) 453, the cylindrical frame 44, and the plurality of rollers 43. The collar front wheel 453 is slidably supported by the mandrel 41. The cylindrical frame 44 is rotatably supported inside the collar front wheel 453. The plurality of rollers 43 are rotatably held by the frame 44. The rotary drive machine 6 rotationally drives the mandrel 41. The clamp device 7 clamps the collar front wheel 453. The clamp moving device 8 moves the clamp device 7 in the axial direction of the expander 4. The feeding device 5 moves the mandrel 41 in the axial direction of the expander 4.
[0053] In this configuration, the clamp moving device 8 moves the frame member 42 toward the distal end of the mandrel 41 via the clamp device 7. Then, the roller 43 held by the frame member 42 moves to the smaller diameter side of the tapered portion 411 of the mandrel 41. The clamp moving device 8 can thus reduce the tool diameter of the expander 4. The robot 2 can thus easily insert the expander 4 into the tube T. This allows the tube expanding device 3 to automatically expand the plurality of tubes T continuously, thereby improving the efficiency of the tube expanding operation.
During the expanding process, an axial external force is applied to the mandrel 41 in an advancing direction. In order to prevent the axial external force and the driving force of the feeding device 5 from pressing against each other, the feeding device 5 is driven by compressed air so as to follow a load that is the axial external force. Thus, the robot 2 does not need to operate according to the external force.
Therefore, according to the present embodiment, it is possible to provide the automatic tube expanding apparatus 1 capable of improving the efficiency of the tube expanding operation by using a general purpose robot.
[0054] Further, in the present embodiment, the collar rear wheel 451 is fixed to the outer peripheral surface of the frame 44, and the collar front wheel 453 is rotatably disposed on the distal end side of the expander 4 with respect to the collar rear wheel 451 via the ball retainer 452. In this configuration, it is possible to easily realize a configuration in which the frame 44 is rotatably supported inside the collar front wheel 453. In this case, when the mandrel 41 advances by itself during the expanding process, the collar front wheel 453 clamped by the clamp device 7 is pressed against the end face of the tube T to be expanded. Thus, it is possible to prevent the tube T to be expanded from being circulated by the rotation of the roller 43 during the expanding process.
[0055] The present embodiment also includes the control device 10 that causes the position of the mandrel 41 to follow the axial movement of the mandrel 41 while the mandrel 41 receives the axial external force. The control device 10 operates the feeding device 5 so as to move the mandrel 41 in the direction of the axial external force. This causes the expander 4 to follow the advancing or retracting of the expander 4 by itself. In this configuration, the feeding device 5 has the mandrel 41 automatically follow its position in accordance with the speed at which the expander 4 advances or retracts by itself due to the action of the feed angle of the roller 43. As a result, it is possible to prevent an extra force from being applied to the tube T to be expanded. This improves the quality of the expansion operation.
[0056] Further, in the present embodiment, the control device 10 performs control to release the holding force of the clamp moving device 8 with respect to the axial position of the clamp device 7. The control to release the holding force is performed in such a manner that the clamp device 7 is moved to the distal end of the mandrel 41 together with the frame member 42 by the clamp moving device 8 in S3, and the frame member 42 is clamped by the clamp device 7 in S4. In this configuration, the clamp moving device 8 is in a floating state that moves to follow the external force. Thus, during the expanding process, when the mandrel 41 advances through the tube T while rotating by the action of the feed angle of the roller 43, the expander 4 can be maintained in a state of being pressed against the end face of the tube T.
[0057] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention, and all technical matters included in the technical idea described in the claims are the subject of the present invention. While the above embodiments have been shown by way of example, those skilled in the art will recognize that various alternatives, modifications, variations, and improvements can be made from the disclosure herein, which fall within the scope of the appended claims.
[0058] For example, in the above-described embodiment, the feeding device 5 is disposed between the distal end portion of the arm 21 of the robot 2 and the rotary drive machine 6, but is not limited thereto. For example, the coupling 9 may be configured to expand and contract in the axial direction, and the feeding device 5 may be configured to move the mandrel 41 by operating the coupling 9 to expand and contract.

Reference Signs List
[0059] 1 Automatic tube expanding apparatus
2 Robot
3 Tube expanding device
4 Expander
41 Mandrel
42 Frame member
43 Roller
44 Frame
451 Collar rear wheel
452 Ball retainer
453 Collar front wheel (collar member)
5 Feeding device
51 Feed cylinder
521 Piston
522 Piston rod
54 Base plate
55 Support
6 Rotary drive machine
7 Clamp device
8 Clamp moving device
81 Cylinder body
821 Piston
822 Piston rod
10 Controller
T Tube , Claims:1. An automatic tube expanding apparatus (1), comprising:
a tube expanding device (3) configured to perform a tube expanding process; and
a robot (2) configured to support and move the tube expanding device (3); wherein
the tube expanding device (3) includes,
an expander (4) including,
a mandrel (41),
a collar member (45) slidably supported by the mandrel (41),
a cylindrical frame (44) rotatably supported inside the collar member (45), and
a plurality of rollers (43) rotatably held by the frame (44),
a rotary drive machine (6) configured to rotationally drive the mandrel (41),
a clamp device (7) configured to clamp the collar member (45),
a clamp moving device (8) configured to move the clamp device (7) in an axial direction of the expander (4), and
a feeding device (5) configured to move the mandrel (41) in the axial direction of the expander (4).

2. The automatic tube expanding apparatus (1) as claimed in claim 1, wherein
a collar rear wheel (451) is fixed to an outer peripheral surface of the frame (44), and
the collar member (45) is rotatably disposed on a distal end side of the expander (4) with respect to the collar rear wheel (451) via a ball retainer (452).

3. The automatic tube expanding apparatus (1) as claimed in claim 1 or 2, further comprising:
a control device (10) configured to cause a position of the mandrel (41) to follow an axial movement of the mandrel (41) while the mandrel (41) receives an axial external force by operating the feeding device (5) such that the mandrel (41) moves in a direction of the axial external force.

4. The automatic tube expanding apparatus (1) as claimed in claim 3, wherein
the control device (10) performs control to release a holding force of the clamp moving device (8) with respect to an axial position of the clamp device (7) in such a manner that the camp device (7) is moved to a distal end of the mandrel (41) by the clamp moving device (8), and the collar member (45) is clamped by the clamp device (8).

5. The automatic tube expanding apparatus (1) as claimed in claim 1 or 2, wherein
the feeding device (5) includes,
a feed cylinder (51) configured to generate a driving force by compressed air,
a piston (521) slidably disposed in the feed cylinder (5),
a piston rod (522) having a basal end fixed to the piston (521) and a distal end protruding and extending from the feed cylinder (51), and
a base plate (54) fixed to the robot (2),
wherein
the base plate (54) includes a support portion (55), and
the piston rod (522) has a distal end connected to the support portion (55).

6. The automatic tube expanding apparatus (1) as claimed in claim 1 or 2, wherein
the clamp moving device (8) includes,
a cylinder body (81) configured to generate a driving force by compressed air,
a piston (821) slidably disposed in the cylinder body (81), and
a piston rod (822) having a basal end connected to the piston (821) and a distal end protruding and extending from the cylinder body (81),
wherein
the piston rod (822) has a distal end connected to the clamp device (7).

7. The automatic tube expanding apparatus (1) as claimed in any one of claims 1 to 6, wherein
the feeding device (5) includes an air cylinder.

8. An automatic tube expanding method, comprising:
moving, by a clamp moving device (8), a frame member (42) having a frame (44) by which a roller (43) is rotatably held toward a distal end of a mandrel (41) to which the frame member (42) is externally fitted;
clamping the frame member (42) by a clamp device (7);
inserting the frame member (42) and the mandrel (41) into a tube (T) by a robot (2);
stopping the robot (2) when the frame member (42) and the mandrel (41) reaches a predetermined position;
feeding, by a feeding device (5), the mandrel (41) rotating in a first direction by a rotary drive machine (6) toward a distal end;
rotating the frame (44) in the first direction to advance the mandrel (41) toward a distal end by itself;
expanding the tube (T) by the roller (43);
temporarily stopping a rotation of the mandrel (41) by the rotary drive machine (6) when a load torque of the rotary drive machine (6) reaches a predetermined set torque;
rotating, by the rotary drive machine (6), the mandrel (41) in a second direction that is a reverse direction of the first direction to cause the frame (44) to rotate in the second direction for the mandrel (41) to retract toward a basal end by itself;
pulling the mandrel (41) rotating in the second direction toward a basal end by the feeding device (5); and
pulling, by the robot (2), the frame member (44) and the mandrel (41) from the tube (T).

9. The automatic tube expanding method as claimed in claim 8, wherein
when the mandrel (41) receives an axial external force while the mandrel (41) rotates in the first direction to advance toward the distal end by itself, and while the mandrel (41) rotates in the second direction to retract toward the basal end by itself, the feeding device (5) moves the mandrel (41) in a direction of the axial external force for a position of the mandrel (41) to follow an axial movement of the mandrel (41).

10. The automatic tube expanding method as claimed in claim 9, wherein
while the clamp moving device (8) moves the clamp device (7) toward a distal end of the mandrel (41), and while the frame member (42) is clamped by the clamp device (7), a retaining force by the clamp moving device (8) in an axial position of the clamp device (7) is released.

11. The automatic tube expanding method as claimed in any one of claims 8 to 10, wherein
the feeding device (5) feeds the mandrel (41) rotating in the first direction by the rotary drive machine (6) toward the distal end by using an air cylinder, and
the feeding device (5) feeds the mandrel (41) rotating in the second direction by the rotary drive machine (6) toward the basal end by using the air cylinder.