JP3894896B2 - Work transfer device for press machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a work transfer device for a press machine that transfers a work using a linear motor as a drive source.
[0002]
[Prior art]
Conventionally, in a transfer press that performs press processing almost simultaneously in a plurality of processing steps, workpiece transfer for loading and unloading a workpiece to be processed to and from the processing position in conjunction with multi-step press processing performed continuously. A device is provided. In this case, the larger the size of the workpiece to be processed, the longer the workpiece conveyance distance. In combination with the high-speed operation of the press, a linear motor is used as the drive source for the workpiece conveyance device, and the workpiece is moved at high speed. Attempts have been made to transport it.
[0003]
On the other hand, even in a tandem press line in which a plurality of press machines are arranged in a line in the workpiece conveyance direction and sequentially press-processed, there is a demand for increasing the workpiece conveyance speed. Have proposed a workpiece transfer device using a linear motor as a drive source (Japanese Patent Application No. 2001-400849). The workpiece transfer device of the prior invention is provided with a lift beam that can move up and down in parallel with the workpiece transfer direction, and a carrier and a subcarrier that are movable along the longitudinal direction of the lift beam. A cross bar having a work holding means is provided, and a linear motor is used as the moving means for moving the carrier.
[0004]
[Problems to be solved by the invention]
By the way, in this type of work transfer device, it is required that the current position of the movable body in the linear motor is detected by an encoder, and that the position control of the movable body is performed accurately in conjunction with the movement of the slide in the press processing station. Is done. In particular, in a conveyance system using a linear motor, since the workpiece is conveyed at high speed, the possibility of interference between the workpiece conveyance device and the mold is increased unless the accuracy of position control is further improved.
[0005]
In addition, if the encoder breaks down during linked operation with the press, the position control of the work transfer device becomes impossible and the possibility of the above-mentioned interference is also increased. It is necessary to keep it.
[0006]
The present invention has been made in view of such circumstances, and in a work transfer device using a linear motor as a drive source, the position of the work transfer device can be accurately controlled, and the encoder fails during linked operation with the press. Even so, an object of the present invention is to provide a workpiece transfer device for a press machine that can reliably prevent the occurrence of an interference accident with a mold.
[0007]
[Means for solving the problems and actions / effects]
In order to achieve the above object, a workpiece transfer device for a press machine according to the present invention comprises:
A workpiece conveying device for a press machine that conveys a workpiece using a linear motor as a drive source,
Said linear motor multi several encoder detecting the position of, and calculating means for calculating a deviation of the values detected by these plurality of encoders based on the calculation result by the calculating means, a deviation of the detected value is the predetermined value An abnormality determining means for determining that any one of the encoders is abnormal when exceeding ,
At least one of the plurality of encoders is an absolute encoder .
[0008]
According to the present invention, since the position information of the linear motor is detected by a plurality of encoders, it is possible to improve the accuracy of position control using these encoders, and the runaway of the work transfer device due to the failure of the encoder. Thus, it is possible to reliably avoid the risk of interference between the workpiece transfer device and the die of the press machine. In addition, the detection values of a plurality of encoders are compared with each other, and when the deviation exceeds a predetermined value, any of the encoders is determined to be abnormal by the abnormality determination means, so that the abnormality detection of the encoder itself can be reliably detected. It can be carried out.
[0009]
In addition, since at least one of the plurality of encoders is an absolute encoder , it is possible to effectively use the absolute position data output characteristic inherent in the absolute encoder. Thus, it is not necessary to set the origin of the movable body or perform magnetic pole detection each time the power is turned off as in the prior art, and the operating rate of the press line can be improved.
[0010]
The abnormality determining means may determine that the encoder is abnormal when the detected value indicates a singular value from the history data of the detected value of the encoder before the occurrence of the abnormality. In this way, when the detection values of a plurality of encoders are different from each other, which encoder is abnormal is determined by the singular value of the detection value by the encoder before the abnormality occurs, in other words, the position or speed value that is impossible. Based on what is shown, the abnormal state of the encoder can be determined.
[0011]
In the present invention, when the abnormality determining means determines that any one of the plurality of encoders is abnormal, the workpiece transfer device is used only by using a detection signal from a normal encoder. It is preferable to provide an abnormal time control means for moving to a predetermined standby point position and stopping. This prevents the workpiece transfer device from becoming uncontrollable due to the abnormality of the encoder, and is moved to the standby point position by the detection signal from the normal encoder. The risk of interference with can be avoided more reliably.
[0012]
In the present invention, it is a work transfer device including a pair of left and right carriers that support a crossbar having a work holding means at both ends thereof, each carrier being driven in the work transfer direction by a biaxial linear motor, It is preferable that an encoder is attached to each linear motor. According to such a workpiece transfer device, the two-axis linear motors attached to the respective carriers are driven without causing misalignment with each other. Therefore, even if one of the two axes malfunctions, the other The work transfer device can be reliably moved to the standby position by the encoder.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, a specific embodiment of a work transfer device for a press machine according to the present invention will be described with reference to the drawings.
[0014]
FIG. 1 shows a partial front view of a tandem press line according to an embodiment of the present invention, and FIG. 2 shows a side view of FIG. FIG. 3 is a cross-sectional view taken along the line AA in FIG.
[0015]
The tandem press line 1 of the present embodiment has a plurality of units arranged in series from the upstream side (left side in FIG. 1) toward the downstream side with a predetermined interval (only two units are shown in FIG. 1). , And a workpiece transfer device (hereinafter referred to as “feeder”) that transfers (unloads / loads) the workpiece 18 (see FIG. 3) between the processing stations of the presses 2 and 3 arranged adjacent to each other. 4).
[0016]
Each of the presses 2 and 3 is supported by an upright 5 serving as a main body frame, an upper frame 6 disposed above the upright 5 and incorporating a driving force transmission mechanism, and supported by the upright 5 so as to be movable up and down. A slide 7 that is moved up and down via a driving force transmission mechanism; and a bolster 9 that is disposed on the bed 8 so as to face the slide 7. The workpiece is processed by a lower mold attached to the upper end of the workpiece.
[0017]
The feeder 4 includes a pair of lift beams 10 that are spaced apart from each other on the left and right sides in the workpiece conveyance direction. A rod 11 extending upward along the upright 5 is attached to the upper portion of the lift beam 10. A rack is engraved on the rod 11, and the rack engages with a pinion that is drivingly connected to the output shaft of the lift shaft servomotor 12 via a power transmission mechanism. 10 is moved up and down.
[0018]
Each of the left and right lift beams 10 is provided with a carrier 14 having a substantially U-shaped cross section so as to be able to move along the longitudinal direction (workpiece conveying direction) of the lift beam 10 so as to hold the lift beam 10 from below. A subcarrier 15 that is movable along the carrier 14 in the workpiece transfer direction is disposed below the carrier 14. A pair of subcarriers 15, 15 facing each other are connected by a cross bar 16, and a plurality of vacuum cups 17 are attached to the lower surface of the cross bar 16, and the workpiece 18 is adsorbed by these vacuum cups 17. It is like that.
[0019]
As shown in FIG. 3, a pair of linear motors 19 are provided as moving means for moving the carrier 14 along the lift beam 10 between the outer side surfaces of the lift beam 10 and the inner side surface of the carrier 14 opposed thereto. Is arranged. Further, the carrier 14 with respect to the lift beam 10 is provided between the upper outer side surfaces of the lift beam 19 and the inner side surface of the carrier 14 opposed thereto and between the lower surface of the lift beam 19 and the bottom surface of the carrier 14 opposed thereto. A linear guide 20 for guiding the moving operation is provided. Here, the linear motor 19 includes a magnet 19a disposed on both side surfaces of the lift beam 10 along the transport direction (longitudinal direction), and a transport direction (longitudinal direction) on the inner surface of the carrier 14 facing the magnet 19a. The armature (carrier 14) having the coil 19b is linearly moved by the change of the magnetic field created on the stator (lift beam 10) having the magnet 19a. Has been.
[0020]
In addition, a linear motor 21 is disposed between the lower surface of the carrier 14 and the upper surface of the subcarrier 15 opposite to the carrier 14 as moving means for transferring the subcarrier 15 along the carrier 14. Linear guides 22 for guiding the movement of the subcarrier 15 relative to the carrier 14 are disposed on both sides of the carrier. The linear motor 21 includes a magnet 21a disposed on the lower surface of the carrier 14 along the transport direction, and a coil 21b disposed on the upper surface of the subcarrier 15 facing the magnet 21a.
[0021]
In the feeder 4 configured as described above, the vacuum cup 17 is moved up and down via the carrier 14, the subcarrier 15, and the crossbar 16 by moving the lift beam 10 up and down by driving the lift shaft servomotor 12. be able to. Further, the carrier 14 is moved along the longitudinal direction of the lift beam 10 by driving the linear motor 18, and the subcarrier 15 is offset in the moving direction of the carrier 14 by driving the linear motor 21. 17 can be moved in the workpiece transfer direction. Thus, by controlling two orthogonal drive shaft positions in the vertical direction and / or the transport direction, the movement trajectory of the vacuum cup 17, in other words, the transport trajectory of the workpiece 18 can be controlled.
[0022]
A rack 23 is attached to one side surface (left side surface in FIG. 3) of the lift beam 10 (on the fixed portion side of the linear motor 19) along the longitudinal direction of the lift beam 10, and a pinion 24 is attached to the rack 23. Meshed. The pinion 24 is fixed to one end portion of an output shaft 25 that is rotatably supported on the side wall of the carrier 14 (the movable portion side of the linear motor 18), and an absolute encoder 26 is attached to the other end portion of the output shaft 25. It is installed. Thus, when the carrier 14 travels along the longitudinal direction of the lift beam 10, the pinion 24 meshing with the rack 23 rotates and the current position (absolute position) of the rotation shaft (output shaft 25) is detected by the absolute encoder 26. can do. Therefore, the position information of the linear motor 19, that is, the position information of the carrier 14 can be detected.
[0023]
On the other hand, a linear encoder (incremental encoder) 27 is provided on the other side surface (right side surface in FIG. 3) of the lift beam 10. The linear encoder 27 includes a magnetic tape 27a attached to the other side surface of the lift beam 10 along the longitudinal direction, and a magnetic head 27b attached to the inner side surface of the carrier 14 so as to face the magnetic tape 27a. It is configured.
[0024]
FIG. 3 shows only the configuration of one side of the crossbar 16, but the other side of the crossbar 16 has the same configuration. Although not shown in the figure, the linear motor 21 that moves the subcarrier 15 is also provided with an encoder similar to the absolute encoder 26, and its position information is detected.
[0025]
The absolute encoder 26 and the linear encoder 27 detect the current position of the linear motor 19, in other words, the current position of the carrier 14, and output the detected position information to a controller (not shown). The controller executes a required calculation based on input information from the encoders 26 and 27 and outputs a command value to a servo amplifier (not shown). In this way, the linear motor 19 is controlled to be in a desired position.
[0026]
Further, in the controller, input data (detected values) from both encoders 26 and 27 are compared and calculated every arbitrary time (for example, 5 ms) by a built-in calculating means during servo control, and both data are detected by an abnormality determining means. It is checked whether or not the deviation exceeds a predetermined threshold value, and when this threshold value is exceeded, it is determined that one of the encoders 26 and 27 has failed. At that time, when the detected value shows a singular value (a possible value) from the history data of the detected values by the encoders 26 and 27 before the occurrence of the abnormality, it is determined that the encoder is abnormal. When the abnormal state of the encoder is determined, the carrier 14 is provided at a predetermined standby point position (usually between the presses 2 and 3 by using the detection signal from the normal encoder only by the abnormal time control means. It is controlled to be moved to stop.
[0027]
As described above, according to the present embodiment, the position information of the linear motor 19 that drives the carrier 14 is detected by a plurality of encoders (four in this embodiment, two on each side). Position control can be performed with high accuracy. In addition, even when one of the plurality of encoders fails, it is possible to reliably prevent the carrier 14 from going out of control and runaway, and linearly based on a detection signal from a normal encoder. The motor 19 can be controlled to retreat to a predetermined standby point position. Therefore, the danger of interference between the feeder 4 and the dies of the presses 2 and 3 can be surely avoided.
[0028]
In addition, since the absolute encoder 26 does not lose position information even when the power is turned off, it is not necessary to perform the origin detection of the carrier 14 or the magnetic pole detection each time the power is turned on, and this kind of complicated work is required. There is an advantage that can be eliminated.
[0029]
In this embodiment, the case where one absolute type encoder 26 and one linear encoder (incremental type encoder) 27 are mounted on one side of the carrier 14 has been described. However, two absolute type encoders 26 (or two linear encoders 27) You may make it wear. Further, a total of two may be mounted on one side of the carrier 14, or only two may be mounted on one side of the carrier 14. Of course, the subcarrier 15 can also be implemented in various modes, such as mounting two pieces on each side or mounting one piece on each side.
[0030]
In the present embodiment, the magnet 19a is provided on the lift beam 10 side and the coil 19b is provided on the carrier 14 side. In this embodiment, the magnet 21a is provided on the carrier 14 side, and the coil 21b is provided on the subcarrier 15 side.
[0031]
In this embodiment, the example applied to the feeder of the tandem press line has been described. However, the present invention is not limited to the tandem press line but can be applied to a feeder of other press machines such as a transfer feeder. Needless to say.
[Brief description of the drawings]
FIG. 1 is a partial front view of a tandem press line according to an embodiment of the present invention.
FIG. 2 is a side view of FIG. 1;
3 is a cross-sectional view taken along the line AA in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tandem press line 2, 3 Press 4 Feeder 10 Lift beam 14 Carrier 15 Subcarrier 19, 21 Linear motor 23 Rack 24 Pinion 26 Absolute type encoder 27 Linear encoder (Incremental type encoder)

Claims (4)

A workpiece conveying device for a press machine that conveys a workpiece using a linear motor as a drive source,
Said linear motor multi several encoder detecting the position of, and calculating means for calculating a deviation of the values detected by these plurality of encoders based on the calculation result by the calculating means, a deviation of the detected value is the predetermined value An abnormality determining means for determining that any one of the encoders is abnormal when exceeding ,
A work conveying apparatus for a press machine, wherein at least one of the plurality of encoders is an absolute encoder . 2. The work conveying apparatus for a press machine according to claim 1 , wherein the abnormality determining means determines that the encoder is abnormal when the detected value indicates a singular value from the history data of the detected value of the encoder before the occurrence of the abnormality. . Further, when it is determined by the abnormality determining means that any one of the plurality of encoders is abnormal, the workpiece transfer device is moved to a predetermined standby position using only a detection signal from the normal encoder. The work conveyance device for a press machine according to claim 2 , further comprising an abnormal-time control unit that is moved to a stop. A workpiece conveying device having a pair of left and right carriers that support a crossbar having workpiece holding means at both ends thereof, each carrier being driven in the workpiece conveying direction by a biaxial linear motor, The work conveying apparatus of a press machine according to claim 3 , wherein an encoder is attached to each.

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