DESCRIPTION

FORGE CRANE SYSTEM

[Technical Field]

[0001]

The present invention relates to a forge crane system, which suspends an object to be forged during a forging operation. In particular, it relates to a forge crane system in which a plurality of forge cranes can work in cooperation with each other to suspend an object to be forged.

Priority is claimed on Japanese Patent Application No. 2010-073173, riled March 26,2010, the content of which is incorporated herein by reference.

[Background Art]

[0002]
In general, a forge crane used in a forge plant is a crane that conveys an object to be forged, and is also used to continue holding the object to be forged during a forging operation by a forging apparatus. A forging process is performed on the object to be forged through the operation of the forge crane, which operates in connection with such a forging apparatus, such that the object to be forged is processed into a predetermined shape.

[0003]
To be specific, the construction of the forge crane comprises, for example, a girder that travels on rails in a building, a trolley that traverses rails on the girder perpendicularly to the building rails, a trolley that travel on the rails, drums supported on the trolleys, on which cable is wound, electric motors that rotate the drums, and the like (for example, refer to Patent Document 1). Here in such a forge crane, when a forging operation is performed, the weight occurring due to the press in the forging apparatus sometimes acts on the cable in addition to the weight of an object to be forged, which is the suspended load. In order to deal with such a weight from the forging apparatus, it is necessary to design the forge crane with a greater safety factor compared with a normal crane, which only lifts a load, and set it so that it can lift a heavy load. Furthermore, in recent years, in forging apparatus, there has been a demand for processing larger objects to be forged, and forge cranes, which lift objects to be forged and work in cooperation with the forging apparatus, are required that can lift heavier objects and objects to be forged with special shapes.

[0004]
For example, in Patent Document 1, a point is disclosed in which two forge cranes work in cooperation to lift an object to be forged and execute a forging operation using a forging apparatus. In such an operation, by the two forge cranes lifting an object to be forged in cooperation and moving it before and after the forging operation, the forging operation can be executed even if it is an object to be forged that is difficult to lift and move using one forge crane due to its weight, size or shape.

[Prior Art Document]
[Patent Documents]

[0005]
[Patent Document 1] Japanese Examined Patent Application, Second Publication No. S45-24939

[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. S63-215333

SUMMARY OF THE INVENTION

[Problems to be Solved by the Invention]

[0006]
Here, in order to convey an object to be forged safely using two forge cranes, it is necessary for the two forge cranes to travel at the same speed without changing their relative positions. Moreover it is necessary for each of the operators to confirm the distance between the two forge cranes visually, and operate each of the forge cranes individually. Therefore, it is desirable for the two forge cranes to be able to be operated at the same time by one operator. However, the loads acting on each of the forge cranes can differ depending on the shape of the object to be forged and the difference in the relative positions between the object to be forged and each of the forge cranes. Moreover, depending on the positional relationship between the two forge cranes and the object to be forged, the direction of the load acting on each of the forge cranes from the object to be forged sometimes differs relative to the direction in which the object to be forged is conveyed, that is, the running direction of the two forge cranes. In such cases, there is a problem in that the traveling speeds of each of the forge cranes differ depending on the size of the load acting on each of the forge cranes and the difference in the directions, creating a difference in the relative positions, which prevents the object to be forged from being conveyed safely.

[0007]
The present invention has been made in consideration of the above circumstances, with an object of providing a forge crane system that can convey an object to be forged stably using a plurality of forge cranes.

[Means for Solving the Problem]

[0008]
A forge crane system of the present invention is provided with: a plurality of forge cranes which travel in a running direction and a lateral direction; and a control unit which controls said forge cranes. Each of the forge crane has suspending equipment that suspends an object to be forged, a driving device for traveling in the running direction, and a traversing device for traveling in the lateral direction. Each of the driving device and the traversing device has an electric motor serving as a driving source, an inverter that controls the electric motor, and a detecting section that detects a rotational state of the electric motor and outputs a detection signal based on the rotational state to the inverter. The control unit output a same traveling speed command to the inverters of the respective forge cranes. The inverter outputs an alternating current that drive the electric motors at a rotational speed according to the traveling speed command, based on the detection signal.

[0009]
According to the forge crane system of the present invention, it is possible to convey an object to be forged by driving each of the forge cranes via driving devices in a state in which one object to be forged is suspended by the suspending equipment of all of a plurality of forge cranes at the same time. Here, when the plurality of forge cranes is instructed to move, the same speed command is output to each of the inverters of the forge cranes at the same time, corresponding to the same speed command output from the control unit to each of the forge cranes. Then, in the driving device of each of the forge cranes, with respect to the speed command input, the inverter outputs an alternating current to the electric motor such that it rotates at a speed according to the speed command based on the rotational state that is detected and output by the rotational state detecting section. Therefore the plurality of forge cranes can travel at a speed corresponding to the same speed command, and thus can travel while keeping their relative positions constant. Therefore it is possible to travel and to convey the object to be forged stably regardless of the shape of the object to be forged, the relative position of each of the plurality of forge cranes with respect to the object to be forged, and the direction of the load acting on each of the forge cranes with respect to the running direction.

[0010]
The arrangement may be such that the driving device of the respective forge cranes has driving wheels that are rotated by the electric motors. The driving wheels are provided at locations at least different in a first direction perpendicular to the running direction. The electric motors and the inverters that control the electric motors may be provided independently for the each location.

[0011]
According to the arrangement, the driving wheels are provided at locations at least different in a first direction perpendicular to the running direction are rotated by the drive of the electric motors under independent control by the mutually different inverters. Therefore even if an object to be forged is lifted such that it is dislocated from the center of the forge cranes in the first direction, it is possible for each of the inverters to output an alternating current to the corresponding electric motors so that they can drive at a rotational speed corresponding to the speed command from the control unit. As a result, it is possible to move each of the forge cranes and convey the object to be forged stably without a difference in the speeds of the driving wheels arranged in the first direction.

[0012]
The arrangement may be such that the traversing device of the respective forge cranes has driving wheels that are rotated by the electric motors. The driving wheels are provided at locations at least different in a second direction perpendicular to the lateral direction. The electric motors and the inverters that control the electric motors may be provided independently for the each location.

[0013]
According to the arrangement, the driving wheels are provided at locations at least different in a second direction perpendicular to the lateral direction are rotated by the drive of the electric motors under independent control by the mutually different inverters.
Therefore even if an object to be forged is lifted such that it is dislocated from the center of the forge cranes in the second direction, it is possible for each of the inverters to output an alternating current to the corresponding electric motors so that they can drive at a rotational speed corresponding to the speed command from the control unit. As a result, it is possible to move each of the forge cranes and convey the object to be forged stably without a difference in the speeds of the driving wheels arranged in the second direction.

[0014]

[Effects of the Invention]

According to the forge crane system of the present invention, it is possible to convey an object to be forged stably using a plurality of forge cranes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]
FIG 1 is a schematic configuration diagram showing a forge crane system according to a embodiment of the present invention.

FIG 2 is a block diagram showing the forge crane system of the present embodiment.

FIG 3 is a plan view showing the detail of a driving device of each of the forge cranes in the forge crane system of the present embodiment.

FIG 4 is a front view to explain a state in which a work piece is suspended using a suspending fixture in the forge crane system of the present embodiment

FIG 5 is a side view in which the suspending fixture is enlarged to describe a state in which a work piece is suspended using the suspending fixture in the forge crane system of the present embodiment.

FIG 6 is an explanatory diagram to describe a state in which the forge cranes are
separated from each other in a case where a work piece is suspended using the suspending fixture in the conventional forge crane system.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016]
An embodiment of the present invention is described, with reference to FIG 1 to FIG 4. FIG 1 to FIG. 3 show a forge crane system of the present embodiment. As shown in FIG 1, a forge crane system 100 of the present embodiment suspends a work piece W, which is an object to be forged, using a plurality of forge cranes 1, and works in cooperation with a forging apparatus 101 to perform a forging process on the work piece W. In the present embodiment, two forge cranes 1 are provided, being forge crane 1A and 1B. [

[0017]
The forging apparatus 101 is provided with; a supporting base 102 on. the top surface of which the work piece W is mounted during forging, a press 103 which is located above the supporting base 102 and applies pressure to the work piece W placed between itself and the supporting base 102, and cylinders 104 which raise and lower the press 103. The forging apparatus 101 performs a work piece W forging operation on the work piece W which is rotated by a turning apparatus 110 suspended from each of the forge cranes 1 of the forge crane system 100. Here the turning apparatus 110 comprises a belt 111 for holding a shaft W1 of the work piece W, and a rotating apparatus 112 for rotating the work piece W together with the shaft W1 around the axis by rotating the belt 111.

[0018]
Next is a description of the forge crane system 100. As shown in FIG 1 and FIG 2, the forge crane system 100 is provided with two forge cranes 1 (1A and 1B) which can travel on a rail L, and a control unit 10 which outputs the same operating command to the
two forge cranes 1A and 1B to operate them. Each of the forge cranes 1 has a supporting section 2 which can travel on the rail L, suspending equipment 3 which is supported by the supporting section 2 fox suspending the work piece W as a suspended load, by a cable 51, and a PLC (Programmable Logic Controller) 4, serving as a main control section that controls each of the components. The PLC 4 receives operating commands output from the control unit 10, and controls of each of the components based on the operating commands. The operating commands include winding operation commands for instructing the suspending equipment 3 to wind up and wind down, traveling speed commands for instructing the running direction and traveling speed of the forge cranes 1 by driving devices 20, which is described later, and the like. Furthermore, in the traveling speed command, the traveling speed is expressed by absolute values, and the running direction is expressed by positive and negative signs, lot example.

[0019]
The supporting section 2 has a driving device 20 so that it can travel on the rail L using wheels 22. The driving device 20 has a frame 21, wheels 22 arranged on the rail L, which are supported by the frame 21 such that they can rotate, a drive motor 23 serving as an electric motor for rotating the wheels 22, a pulse generator 24 serving as a detecting section for obtaining angle information as a rotational state of the drive motor 23, and an inverter 25 for controlling the drive motor 23. Moreover, the supporting section 2 has a traversing device 27 for traveling on the frame 21 with a first direction perpendicular to the running direction by the driving device 20, as the lateral direction. The traversing device 27 comprises a trolley arranged on the frame 21, and similarly to the driving device, the trolley has wheels that can rotate in the lateral direction, a traverse motor serving as an electric motor for rotating the wheels, a pulse generator serving as a detecting section for obtaining angle information as a rotational state of the traverse motor, and an inverter for controlling the traverse motor, which are not shown in the figure.

[0020]
As shown in FIG 3, in the present embodiment, the driving device 20 of each of the forge cranes 1 has two rows of wheel groups 26A and 26B in a first direction perpendicular to the running direction (direction of travel) X parallel to the rails L. Each of the wheel groups 26A and 26B comprises six wheels 22 provided along the running direction X. Furthermore, in each of the wheel groups 26A and 26B,two of the six wheels 22 are constructed as driving wheels 22-1, and the remaining four are constructed as driven wheels 22-2. The driving wheels 22-1 are connected to respective drive motors 23, which enables the drive motors 23 to transmit the rotational diving force. Moreover, as shown in FIG 2, each of the driving devices 20 is provided with two inverters 25 such that they can control each of the wheel groups 26A and 26B independently. In each of the wheel groups 26A and 26B, the two drive motors 23 corresponding to the two driving wheels 22-1 are connected to the same inverter 25. The inverters 25 are possible to output the same alternating current to the drive motors 23. Furthermore, of the two drive motors 23, one is connected to the pulse generator 24 so that it is possible to detect the rotational position as a rotational state. The pulse generator 24 connected to one of the drive motors 23 can output the detected rotational position to the inverter 25 as angle information 6.

[0021]
As described above, as shown in FIG 2, in the present embodiment, each of the two forge cranes 1 is provided with two inverters 25 and four drive motors 23, corresponding to the two wheel groups 26A and 26B. The two inverters 25 are connected to a PLC 4, and output an alternating current to the corresponding drive motors 23 according to the same traveling speed command ω0output from the control unit 10 via the PLC 4. Here, as shown in FIG 2, each inverter 25 is provided with an inverter body 25a, a1 differentiator 25b and a subtractor 25c. The inverter body 25a converts an alternating current input from an alternating current supply into direct current based on the traveling speed command ω0 from the PLC. After that, the inverter body 25a outputs alternating current with a frequency and amplitude corresponding to the traveling speed command ω0 . The differentiator 25b obtains angle information G from the pulse generator 24 fitted to the drive motor 23, and calculates the current rotational speed ω. The subtractor 25c calculates the difference ∆ ω0f the rotational speed co output from the differentiator 25b subtracted from the traveling speed command ω0 from the PLC 4, and outputs it to the inverter body 25a. The arrangement may be such that the pulse generator 24 not only detects the rotational position, but also detects the rotational speed as a rotational state. In this case, the differentiator 25b in the inverter 25 is unnecessary.

[0022]
The suspending equipment 3 has a suspending device 30, a cable 31, a plurality of pulleys 32, a drum 34, a main hoist motor and a main hoist inverter. The main hoist motor and the main hoist inverter are not shown in the figure. The suspending device 30 is provided for supporting the turning apparatus 110. The cable 31 is provided for suspending the suspending device 30, and is wounded around the pulleys 32 and 33. One end 31 a of the cable 31 that passes round the pulleys 32 and 33 is wounded on the drum 34. The main hoist motor rotates the drum 34. The main hoist inverter is provided for controlling the main hoist motor. The turning apparatus 110 is engaged with a hook 30a of the suspending device 30.

[0023]
In FIG 1, the suspending equipment 3 suspends the work piece W via the turning apparatus 110. However, in the case where the work piece W does not need to be rotated during forging, or in the case where the work piece W is only conveyed, the arrangement may be such that the work piece W is engaged with the hook 30a of the suspending device 30 directly without using the turning apparatus 110, or the work piece W is suspended using another suspending fixture. FIG 4 and FIG 5 show an example of the suspending fixture. As shown in FIG 4 and FIG. 5, a suspending fixture 50 is provided with tongs 51 for clamping the work piece W, and a beam 52 for suspending the tongs 51. The tongs 51 comprise a pair of grasping members 54 pinned and connected to each other at a rotational supporting section 53 in the central part such that they can rotate, a supporting member 55 for supporting the proximal end 54a of the grasping members 54, and a U-shaped engagement part 56 provided on the supporting member 55. The grasping members 54 have engaging sections 54c formed like a hook at their ends 54b such that they can grasp and hold the work piece W on the portion closer to the distal end than the rotational supporting section 53. Furthermore, the proximal end 54a of the grasping members 54 are supported by the supporting member 55 such that they can slide toward each other in the direction that grasps the work piece W.

[0024]
The beam 52 has a hook 57 for engaging with the engagement part 56 of the tongs 51, a beam body 58 for supporting the hook 57, and a pair of U-shaped engagement parts 59. U-shaped engagement parts 59 are provided at the two ends of the beam body 58. The hooks 30a of the suspending devices 30 of each of the forge cranes 1 are engaged with the engagement part 59. The engagement part 56 on the supporting member 55 of the tongs 51, and the hook 57 on the beam 52, are located substantially in the center of the supporting member 55 and the beam body 58. Furthermore, the pair of engagement parts 59 on the beam 52 are located symmetrical about the center of the beam body 58. Therefore the loads of the work piece W and the suspending fixture 50 act equally on the hooks 30a of the two forge cranes 1, which suspend the work piece W using the suspending fixture 50.

[0025]
Next is a description of a function of the forge crane system 100 of the present embodiment using as an example a case in which a work piece W is conveyed by the suspending fixture 50 shown in FIG 4.

In the case where the work piece W is conveyed along the rails L by the two forge cranes 1 constituting the forge crane system 100 of the present embodiment working in cooperation, a desired direction and speed are input in the control unit l 0. By so doing, the control unit 10 outputs the same traveling speed command ω0 corresponding to the input to the two inverters 25 provided in each of the forge cranes 1, making four in total, via the PLC 4. Each of the inverters 25 sets frequency and amplitude of an alternating current so as to be a rotational speed of the drive motor 23 corresponding to the traveling speed command coo, and outputs the alternating current to the two corresponding drive motors 23. As a result, each of the forge cranes 1 is going to travel in the running direction X at the traveling speed input in the control unit 10 through the rotation of driving wheels 22-1 in each of the wheel groups 26A and 26B.

[0026]
Furthermore, in one of the two drive motors 23 corresponding to each of the inverters 25, the pulse generator 24 outputs angle information 8 to the inverter 25. Then, the inverter 25 calculates the current rotational speed ωin the differentiator 25b based on the angle information 0 output from the pulse generator 24, and outputs it to the subtractor 25c. The subtractor 25c calculates the difference Δω by subtracting the current rotational speed Ω, output from the differentiator 25b, from the traveling speed command ω0output from the PLC 4, and outputs it to the inverter body 25a. Therefore the inverter body 25a can generate an alternating current, whereby the drive motor 23 rotates at a rotational speed corresponding to the traveling speed command ω0 in consideration of the difference ∆ ω, and output it.

[0027]
Normally, the two forge cranes 1 are in a state in which equal loads act in the vertical direction as in FIG 4 due to the suspending fixture 50. However, if the distance between the forge cranes 1 changes for some reason, loads act on each of the forge cranes 1 in a direction inclined with respect to the vertical direction. Causes that can change the distance in this manner are, for example, that at the start of movement, the distance between the forge cranes 1 varies slightly relative to the distance between the engagement parts 59 on the beam 52, a difference in speed between the forge cranes 1 occurs due to a slight difference in the response time of each of the drive motors 23, a slight oscillation of the suspended load, a slight difference in the rolling friction of the rail L and the wheels 22 of the forge cranes 1, and the like.

[0028]
FIG 6 shows a case where the distance between the forge cranes 1 is greater than the distance between the pair of engagement parts 59 on the beam 52 due to the above-described causes. As shown in FIG 6, in such a case, a force component Fv acts in the vertical direction on each of the forge cranes 1 due to a load Fo, and also a force component Fh acts in the horizontal direction toward the center line of the beam 52 from each of the forge cranes 1, so that the force components Fh in the horizontal direction are reversed between the two forge cranes 1. Therefore, in the case where the two forge cranes 1 arc instructed to travel to convey the work piece W, the horizontal direction force components Fh act as a torque to decelerate the drive motor 23 of the forge crane 1 on the front XI side in the running direction X, and act as a torque to accelerate the forge crane 1 on the rear X2 side.

[0029]
In such a case, if traveling speed commands are output to each of the drive motors of a conventional forge crane such that they rotate at a predetermined speed, each of the drive motors are going to rotate at a rotational speed corresponding to the appropriate traveling speed command. However, due to the torque acting through the weight of the suspended load, the forge crane on the front X1 side in the running direction X becomes slower than the traveling speed corresponding to the traveling speed command due to deceleration. Furthermore the forge crane on the rear X2 side becomes faster than the traveling speed corresponding to the traveling speed command due to acceleration. As a result, the distance between the two narrows, Moreover, in the case where the distance between the forge cranes becomes smaller than the distance between the pair of engagement parts 59 of the beam 52, the situation becomes opposite to the above. That is, the forge crane on the front XI side in the running direction X becomes faster than the traveling speed corresponding to the traveling speed command due to acceleration. Furthermore the forge crane 1 on the rear X2 side becomes slower than the traveling speed corresponding to the traveling speed command due to deceleration. As a result, the distance between the two becomes larger. Moreover, since the change in speed of the forge cranes occurs due to acceleration and deceleration caused by the weight of the suspended load, in the conventional forge cranes, the change in speeds occurs with a delay from the change in mutual position. As a result, the forge cranes repeat the approach and separation.

[0030]
On the other hand, in the forge crane 1 of the present embodiment, the inverters 25 obtain angle information θ from the pulse generator 24 connected to corresponding drive motors 23 as a rotational state, and obtain the current rotational speed Ω from the angle information 6. Furthermore each of the inverters 25 controls the frequency and amplitude of the alternating current output to the drive motors 23 based on the difference A ω between the traveling speed command ©o and the current rotational speed to such that the rotational speeds correspond to the traveling speed command ωo. Therefore, regardless of the torque generated by a disturbance such as the suspended load, frictional resistance, and the like, it is possible to always drive the drive motors 23 at a rotational speed corresponding to the traveling speed command ω0 to rotate the driving wheels 22-1. Moreover, since the same traveling speed command ω0 is output from the control unit 10 to the inverters 25 of each of the forge cranes 1, the two forge cranes 1 can travel at a traveling speed corresponding to the same traveling speed command coo to convey the work piece W stably.

[0031]
In the above description, an example is shown in which conveyance is performed using the suspending fixture 50. However, this is not a limitation, and as shown in FIG. 1, the work piece W to be conveyed may be lifted via the turning apparatus 110 or directly. In this case, if the shape of the work piece W is asymmetrical, regardless of the relative position of the forge cranes 1, the load acting on each of the forge cranes 1 changes due to the asymmetry of the shape of the work piece W and the relative position relationship between the work piece W and each of the forge cranes 1. However, even in such a case, it is possible to move the two forge cranes 1 at the traveling speed corresponding to the traveling speed command ω0 stably to convey the work piece W.

[0032]
Furthermore, in the forge crane 1 of the forge crane system 100 of the present embodiment, the driving wheels 22-1 provided at locations at least different in a first direction perpendicular to the running direction X are rotated by the drive of the drive motors 23 under independent control by the mutually different inverters 25. Therefore even if a work piece W is lifted such that it is dislocated in a direction perpendicular to the running direction X from the center of the forge cranes 1, it is possible for each of the
inverters 25 to output an alternating current to the corresponding drive motors 23 so that they can drive at a rotational speed corresponding to a traveling speed command ω0 from the control unit 10. As a result, it is possible to move each of the forge cranes 1 and convey the work piece W more stably without a difference in the speeds of the driving wheels 22-1 arranged in the direction perpendicular to the running direction X.

[0033]
While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.

[0034]
The forge crane system 100 of the above-described embodiment comprises two forge cranes 1. However this is not a limitation, and there may be three or more. Moreover, the numbers of inverters, driving wheels, and drive motors of each of the forge cranes 1 are examples, provided at least one set is included. Furthermore, in the above, only the drive for traveling is described. However, the same control is performed for a transverse drive comprising the driving device 20 by which a trolley travels on a rail provided on a girder, so that it is possible for the two forge cranes to travel in lateral direction to convey an object to be forged stably.

[Brief Description of the Reference Symbols]

[0035]
1 Forge crane
3 Suspending equipment
10 Control unit
20 Driving device
22-1 Driving wheels
23 Drive motor (motor)
24Pulse generator (rotational state detecting section)
25Inverter
100 Forge crane system
W Work piece W (object to be forged)
X Running direction (Direction of travel)

What is claimed is:

1. A forge crane system which conveys an object to be forged, comprising:

a plurality of forge cranes which travel in a running direction and a lateral direction; and

a control unit which controls said forge cranes,

wherein each of said forge crane has suspending equipment that suspends an object to be forged, a driving device for traveling in said running direction, and a traversing device for traveling in said lateral direction,

each of said driving device and said traversing device has an electric motor serving as a driving source, an inverter that controls the electric motor, and a detecting section that detects a rotational state of said electric motor and outputs a detection signal based on the rotational state to said inverter,

said control unit output a same traveling speed command to said inverters of the said respective forge cranes, and

said inverter outputs an alternating current that drive said electric motors at a rotational speed according to said traveling speed command, based on said detection signal.

2. A forge crane system according to claim 1, wherein

said driving device of the respective forge cranes has driving wheels that are rotated by said electric motors,

said driving wheels are provided at locations at least different in a first direction perpendicular to said running direction, and

said electric motors and said inverters that control the electric motors are provided
independently for each said location.

3. A forge crane system according to cither one of claim 1 and claim 2, wherein

said traversing device of the respective forge cranes has driving wheels that are
rotated by said electric motors,

said driving wheels are provided at locations at least different in a second
direction perpendicular to said lateral direction, and

said electric motors and said inverters that control the electric motors are provided
independently for each said location.