JP2004255418A - Work carrier of press machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform positional control of a work carrier with a linear motor as a drive source thereof with excellent accuracy, and to reliably prevent any accidental interference with a die even when an encoder fails during the interlocking operation with a press. <P>SOLUTION: A plurality of encoders 26 and 27 to detect the position of a linear motor 19 are provided, the deviation of detected values by the plurality of encoders is operated, and based on the result of the operation, it is determined that any one of the encoders 26 and 27 is abnormal if the deviation of the detected value exceeds a predetermined value. Further, if any encoder is abnormal, a work carrier is moved to a predetermined waiting point position by using only the detected signal from a normal encoder, and stopped. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD 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 in which press working is performed at substantially the same time in a plurality of processing steps, work transfer for loading and unloading a work to be processed to and from a processing position in conjunction with continuous multi-step press working. Equipment is provided. In this case, the larger the size of the work to be processed, the longer the work transfer distance becomes. Therefore, in conjunction with the high-speed operation of the press, the work can be moved at high speed by using a linear motor as the drive source of the work transfer device. Attempts have been made to transport them.
[0003]
On the other hand, in a tandem press line in which a plurality of press machines are arranged in a line in the work transfer direction and press work is performed sequentially, there is a demand for a higher work transfer speed. Has proposed a work transfer device using a linear motor as a drive source (Japanese Patent Application No. 2001-400849). The work transfer device of the invention of the prior application provides a lift beam that can move up and down in parallel with the work transfer direction, and a carrier and a subcarrier that can move along the longitudinal direction of the lift beam. And a crossbar having a work holding means, and a linear motor is used as a 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 a movable body in a linear motor be detected by an encoder, and the position control of the movable body be accurately performed in conjunction with the slide movement in a press working station. Is done. In particular, in a transfer system using a linear motor, the work is transferred at a high speed, and unless the position control accuracy is further improved, the possibility of interference between the work transfer device and the mold increases.
[0005]
Also, if the encoder fails during the interlocking operation with the press, the position control of the work transfer device becomes impossible and the possibility of the above-mentioned interference also increases. It is necessary to keep.
[0006]
The present invention has been made in view of such circumstances, and in a work transfer device that uses a linear motor as a drive source, the position of the work transfer device can be accurately controlled, and the encoder may malfunction during the interlocking operation with the press. An object of the present invention is to provide a work 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 Functions / Effects]
In order to achieve the above object, a work transfer device for a press machine according to the present invention includes:
A work transfer device for a press machine that transfers a work using a linear motor as a drive source,
A plurality of encoders are provided for detecting the position of the linear motor, and a calculating means for calculating a deviation of a detection value by the plurality of encoders, and based on a calculation result by the calculating means, a deviation of the detection value is calculated. Abnormality determining means for determining that any one of the encoders is abnormal when a predetermined value is exceeded.
[0008]
According to the present invention, since the detection of the position information of the linear motor is performed by a plurality of encoders, the accuracy of position control using these encoders can be improved, and the runaway of the work transfer device due to a failure of the encoder can be improved. Thus, the risk of interference between the work transfer device and the die of the press machine can be reliably avoided. Further, the values detected by the plurality of encoders are compared with each other, and when the deviation exceeds a predetermined value, the abnormality determination means determines that one of the encoders is abnormal. It can be carried out.
[0009]
In the present invention, it is preferable that at least one of the plurality of encoders is an absolute encoder. This makes it possible to effectively use the characteristic of the absolute encoder, which outputs absolute position data, and to set the origin of the movable body every time the power is turned off, as in the related art. Also, it is not necessary to perform magnetic pole detection, and the operating rate of the press line can be improved.
[0010]
Preferably, the abnormality determination means determines that the encoder is abnormal when a value detected by the encoder immediately before the abnormality determination indicates a singular value. When the detection values of a plurality of encoders are different from each other in this way, which encoder is abnormal is determined by the detection value of the encoder before the occurrence of the abnormality being a singular value, in other words, an impossible position or speed value. Based on the information, the abnormal state of the encoder can be determined.
[0011]
In the present invention, further, when any one of the plurality of encoders is determined to be abnormal by the abnormality determining means, the work transfer device is configured to use the detection signal from the normal encoder only. It is preferable to include an abnormal-time control unit that moves to a predetermined standby point position and stops. This prevents the work transfer device from becoming uncontrollable due to an abnormality in the encoder, and is moved to the standby point position by a detection signal from a normal encoder. Danger of interference with the vehicle can be avoided more reliably.
[0012]
According to the present invention, there is provided a work transfer device including a pair of left and right carriers that support a crossbar having a work holding unit at both ends thereof, and each carrier is driven in a work transfer direction by a biaxial linear motor. It is preferable that each linear motor is provided with an encoder. According to such a work transfer device, since the two-axis linear motors attached to the respective carriers are driven without causing a mutual positional shift, even if one of the two shafts is out of order, the other is driven. With this encoder, the work transfer device can be reliably moved to the standby point position.
[0013]
BEST MODE FOR CARRYING OUT 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 is a partial front view of a tandem press line according to an embodiment of the present invention, and FIG. 2 is a side view of FIG. FIG. 3 is a sectional view taken along line AA of FIG.
[0015]
A plurality of tandem press lines 1 of the present embodiment are arranged in series from the upstream side (left side in FIG. 1) to the downstream side at a predetermined interval from each other (only two are shown in FIG. 1). Work transfer device (hereinafter, referred to as a "feeder") for transferring (unloading / loading) a work 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 includes an upright 5 serving as a main body frame, an upper frame 6 disposed above the upright 5 and having a built-in driving force transmission mechanism, and supported by the upright 5 so as to be vertically movable. A slide 7 that is moved up and down via a driving force transmission mechanism; and a bolster 9 that is disposed opposite to the slide 7 and that is provided on a bed 8. The workpiece is machined by a lower mold mounted on the upper end of the workpiece.
[0017]
The feeder 4 is provided with a pair of lift beams 10 which are arranged on both left and right sides in the work transfer direction so as to be separated from each other. A rod 11 extending upward along the upright 5 is attached to an upper portion of the lift beam 10. A rack is engraved on the rod 11, and the rack meshes with a pinion which is drivingly connected to an output shaft of a 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 hold the lift beam 10 from below so as to be movable in the longitudinal direction (work transfer direction) of the lift beam 10. Below the carrier 14, a sub-carrier 15 movable along the carrier 14 in the work transfer direction is arranged. A pair of subcarriers 15 facing each other are connected by a crossbar 16, and a plurality of vacuum cups 17 are mounted on the lower surface of the crossbar 16, and the workpieces 18 are sucked by the vacuum cups 17. It has become.
[0019]
As shown in FIG. 3, a pair of linear motors 19 as moving means for moving the carrier 14 along the lift beam 10 is provided between both outer side surfaces of the lift beam 10 and the inner side surface of the carrier 14 opposed thereto. Is arranged. Also, the carrier 14 for the lift beam 10 is located between the upper and outer surfaces of the lift beam 19 and the inner surface of the carrier 14 facing the lift beam 19 and between the lower surface of the lift beam 19 and the bottom surface of the carrier 14 facing the lift beam 10, respectively. A linear guide 20 for guiding the moving operation of the camera is provided. Here, the linear motor 19 includes a magnet 19a disposed on both sides 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. And an armature (carrier 14) having the coil 19b is moved linearly by a change in a magnetic field created on a stator (lift beam 10) having a magnet 19a. Have been.
[0020]
A linear motor 21 as a moving means for moving the subcarrier 15 along the carrier 14 is disposed between the lower surface of the carrier 14 and the upper surface of the subcarrier 15 opposed thereto. Linear guides 22 for guiding the movement of the subcarrier 15 with respect to the carrier 14 are disposed on both sides of the linear guide 22. 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 lift beam 10 is moved up and down by driving the lift axis servomotor 12, so that the vacuum cup 17 is moved up and down via the carrier 14, the subcarrier 15 and the crossbar 16. be able to. Further, by driving the linear motor 18 to move the carrier 14 in the longitudinal direction of the lift beam 10 and driving the linear motor 21 to offset the subcarrier 15 in the moving direction of the carrier 14, the crossbar 16 and the vacuum cup 17 can be moved in the work transfer direction. In this way, by controlling two orthogonal drive shaft positions in the vertical direction and / or the transport direction, it is possible to control the movement trajectory of the vacuum cup 17, in other words, the transport trajectory of the work 18.
[0022]
A rack 23 is attached to one side surface (the left side surface in FIG. 3) of the lift beam 10 (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. Has been engaged. The pinion 24 is fixed to one end of an output shaft 25 rotatably supported on a side wall of the carrier 14 (the movable portion side of the linear motor 18). An absolute encoder 26 is attached to the other end of the output shaft 25. It is installed. When the carrier 14 travels in 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, in other words, 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 (the right side 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 mounted on the inner side surface of the carrier 14 so as to face the magnetic tape 27a. It is configured.
[0024]
Although FIG. 3 shows only the configuration of one side of the crossbar 16, the other configuration of the crossbar 16 has the same configuration. Although not shown in the figure, the linear motor 21 for moving the subcarrier 15 is also provided with an encoder similar to the absolute encoder 26, and the 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 performs a required operation based on the input information from each of the encoders 26 and 27 and outputs a command value to a servo amplifier (not shown). Thus, the linear motor 19 is controlled so as to be at a desired position.
[0026]
In the controller, the input data (detected values) from both encoders 26 and 27 are compared and calculated at an arbitrary time (for example, 5 ms) by a built-in calculating means during servo control, and the abnormality determining means compares the two data. It is checked whether the deviation exceeds a predetermined threshold, and when it exceeds this threshold, it is determined that one of the encoders 26 and 27 has failed. At this time, when the detected value indicates a singular value (impossible value) from the history data of the detected values by the encoders 26 and 27 before the occurrence of the abnormality, the encoder is determined to be abnormal. Then, when the abnormal state of the encoder is determined, the abnormal time control means places the carrier 14 at a predetermined standby point position (usually in the middle between the presses 2 and 3) using only the detection signal from the normal encoder. Is controlled so as to be stopped.
[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 (two in each embodiment, four on each side). Position control can be performed with high accuracy. Further, even if one of the plurality of encoders fails, it is possible to reliably prevent the carrier 14 from going out of control due to uncontrollability and to perform linear control based on a detection signal from a normal encoder. The motor 19 can be controlled to be retracted to a predetermined standby point position. Therefore, the risk of interference between the feeder 4 and the dies of the presses 2 and 3 can be reliably avoided.
[0028]
Further, since the absolute type encoder 26 does not lose the position information even when the power is turned off, it is not necessary to perform the home search of the carrier 14 and the magnetic pole detection every time the power is turned on. There is an advantage that can be eliminated.
[0029]
In the present embodiment, the one in which one absolute encoder 26 and one linear encoder (incremental encoder) 27 are mounted on one side of the carrier 14 has been described. However, two absolute encoders 26 (or two ). Further, two carriers may be mounted on each side of the carrier 14, or two carriers may be mounted on one side of the carrier 14. Of course, the subcarriers 15 can also be implemented in various modes such as mounting two on each side or mounting one 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, but they may be provided in reverse. In the present embodiment, the magnet 21a is provided on the carrier 14 side and the coil 21b is provided on the subcarrier 15 side, but may be provided in reverse.
[0031]
In the present embodiment, an example in which the present invention is applied to a feeder of a tandem press line has been described. 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;
FIG. 3 is a sectional view taken along line AA of FIG. 1;
[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 encoder 27 Linear encoder (incremental encoder)

Claims (5)

A work transfer device for a press machine that transfers a work using a linear motor as a drive source,
A plurality of encoders are provided for detecting the position of the linear motor, and a calculating means for calculating a deviation of a detection value by the plurality of encoders, and based on a calculation result by the calculating means, a deviation of the detection value is calculated. A workpiece transfer device for a press machine, comprising: an abnormality determining unit configured to determine that one of the encoders is abnormal when a predetermined value is exceeded. The work transfer device of a press machine according to claim 1, wherein at least one of the plurality of encoders is an absolute encoder. 3. The work transfer device for a press machine according to claim 1, wherein the abnormality determination unit determines that the encoder is abnormal when a value detected by the encoder immediately before the abnormality determination indicates a singular value. 4. Further, when any one of the plurality of encoders is determined to be abnormal by the abnormality determining means, the work transfer device is moved to a predetermined standby point position using only a detection signal from the normal encoder. 4. The work transfer device for a press machine according to claim 3, further comprising an abnormal-time control means for moving the work piece to a stop position. A work transfer device comprising a pair of left and right carriers that support a crossbar having a work holding means at both ends thereof, wherein each carrier is driven by a biaxial linear motor in the work transfer direction. 5. The work transfer device for a press machine according to claim 4, further comprising an encoder.

Images