Learning system for automatic workpiece transport device

Abstract

The teaching system for an automatic workpiece transport device is a teaching system for an automatic workpiece transport device that simplifies the teaching process and delivers a workpiece, gripped by a robot-side clamping device configured in a robot hand, to a partner device. The teaching system includes a contact detection device provided in the robot hand and configured to detect contact at a predetermined section with the partner device, and a control device configured to calculate a position of the robot hand during contact based on a contact detection signal from the contact detection device.

Description

Technical field

[0001] The present invention relates to a teaching system for carrying out a teaching process in an automatic workpiece transport device. State of the art

[0002] In an articulated robot performing a predetermined task, such as placing a workpiece against a partner device, origin detection is carried out for each drive axis using an origin marker, positioning pin, or similar device. Similarly, the robot is trained to store an operation according to a control program. For example, in the case of a transport robot, it is necessary to move a workpiece to a precise position by executing a stored control program. However, if an error occurs in the component accuracy of the robot or in the partner device that receives the workpiece, the work performed by the numerical control cannot be carried out accurately. Therefore, although the training was performed conventionally, patent literature 1 discloses a training system for this purpose.

[0003] This state of the art describes a teaching system for an articulated robot that moves a workpiece, held at one end by a clamping device, to a target position. In this system, the position of the clamping device and the position of the workpiece are roughly aligned, and the workpiece, transported to a predetermined position, is gripped by the clamping device. If, at this point, there is a discrepancy between the center positions of the clamping device and the workpiece, the sliding element on the clamping device side moves so that the center positions of the clamping device and the workpiece coincide. The position of the clamping device is detected by the sensor, and the actual position of the clamping device is calculated in the computation section based on the position data. Patent literature

[0004] Patent Literature 1: JP A-H7-75986 Summary of the invention: Technical problem

[0005] The conventional teaching system described above is designed to provide a sliding mechanism in an articulated robot and requires a special structure for the robot itself. Because this special structure is added, the cost of the articulated robot increases. Furthermore, the sliding mechanism makes the articulated robot structurally weak, which can easily lead to failure. Therefore, teaching can be performed by an operator without adding such a special structure. For example, in a case where deviation occurs at the center position because the side of the transport robot is pulled during workpiece feeding, the operator can adjust the center position alignment to eliminate the deviation by visually verifying the change.Although such an adjustment does not pose a structural problem, it strongly affects the operator's ability to perform the adjustment accurately, so there would be large differences in the number of steps and accuracy depending on the operator.

[0006] Accordingly, it is an object of the present invention to provide a teaching system for an automatic workpiece transport device that can be implemented more simply in order to solve the problems mentioned above. Solution to the problem

[0007] In one aspect of the present invention, a learning system for an automatic workpiece transport device, configured to deliver a workpiece gripped by a robot-side clamping device configured in a robot hand, to a partner device, a contact detection device provided in the robot hand and configured to detect contact at a predetermined section with the partner device, and a control device configured to calculate a position of the robot hand during contact based on a contact detection signal from the contact detection device. Advantageous effect of the invention

[0008] Because the contact detection device integrated into the robot hand, such as a push button, detects contact at a predetermined point with the partner device, and the control device calculates the robot hand's position during contact based on the contact detection signal, the above configuration simplifies the learning process. Furthermore, this configuration eliminates the need for a complex structure like those found in conventional technology, and variations in accuracy and operating time dependent on operator skill are avoided. Brief description of the drawings Fig. Figure 1 is a perspective view showing the main structure of a multifunctional machining center. Fig. Figure 2 is a side view of the multifunctional machining center, which includes an automatic workpiece transport device and an automatic tool changing device. Fig. Figure 3 is a conceptual view representing a control system for the multifunctional processing machine. Fig. Figure 4 is a perspective view showing a lifting and lowering arm section of the automatic workpiece transport device. Fig. Figure 5 is a view that represents a working state of the learning process as seen from above in an X-axis direction. Fig. Figure 6 is a view showing a working state of the learning process seen from above in the X-axis direction, in which a workpiece is gripped on one side. Fig. Figure 7 is a view that shows a working state of the learning process in a depth direction seen from above in the X-axis direction. Description of the embodiments

[0009] An embodiment of a training system for an automatic workpiece transport device according to the present invention will be described below with reference to the drawings. First, the automatic workpiece transport device of the present embodiment is integrated into a multifunctional machine tool, and Fig. Figure 1 is a perspective view showing the main structure of the multifunctional machine tool. The multifunctional machine tool 1 is a machine tool with various machining devices that fulfill the functions of both an NC lathe and a machining center. Specifically, the multifunctional machine tool 1 is a counter-rotating biaxial lathe in which a first workpiece main spindle device 3 and a second workpiece main spindle device 4 for gripping the workpiece W, and a first turret device 5 and a second turret device 6 with multiple tools T are arranged symmetrically to each other in a left-right direction. Additionally, the tool main spindle device 2 is provided in the center of a machine body.

[0010] The main spindle-side clamping device 11 is mounted on the spindle of the main spindle stand 12, and a pair of first and second workpiece main spindle fixtures 3 and 4 rotate through the drive of the spindle motor 13, so that the workpiece W is subject to phase determination during machining and rotation at a predetermined speed. The main spindle stand 12 and the spindle motor 13 are mounted on the main spindle slide 14 and are configured to move on the bed 7 in a Z-axis direction, which is a width direction of the machine body (an axial direction of the spindle of the main spindle stand 12). In addition, in the first turret fixture 5 and the second turret fixture 6, the pivot indexing of the tool T (turret tool), which is mounted on the turret 15, is carried out by the rotation control of the indexing servo motor 16.To move the tool T into a machining position for the workpiece W, a drive mechanism is provided so that the turret 15 moves in two directions, i.e. a YL axis in a front-back direction of the machine body and an XL axis in an up-down direction of the machine body, which are orthogonal to a Z axis (see . Fig. 2).

[0011] The tool-main spindle assembly 2 has a built-in main spindle head 17, which houses a main spindle servo motor and a tool spindle, and is mounted on a main spindle slide 18 that is movable in an X-axis direction perpendicular to the front and rear of the machine body. The main spindle slide 18 is mounted on a base slide 19 that is movable in a Y-axis direction horizontally to the front and rear of the machine body. The main spindle head 17 is configured so that the tool T (main spindle head tool) is exchanged depending on the machining operation and rotates about a B-axis parallel to the Y-axis. The YL-axis and the XL-axis, which represent the directions of movement of the turret 15 described above, are inclined at 45 degrees to the Y-axis and the X-axis, as shown in Fig. 2 shown.

[0012] Fig. Figure 2 is a side view of the multifunctional machine tool 1, to which the automatic workpiece transport device and the automatic tool changer have been added. In the multifunctional machine tool 1, the automatic tool changer 8 for automatically exchanging the tool T (main spindle head tool) with respect to the tool-main spindle device 2 is provided on a central front part of the machine body. In the automatic tool changer 8, a tool magazine 21, which houses several tools T, is provided on an upper section, so that the tool change is carried out by the tool changer 22, which faces the main spindle head 17. A shifting mechanism for moving a tool is provided between the main spindle head 17 and the tool changer 22.

[0013] The multifunctional machining center 1 is equipped with an automatic workpiece transport device 9 for feeding and removing workpieces W to and from the first and second workpiece main spindle fixtures 3 and 4. In the multifunctional machining center 1, the frame structure 10, which has a turret shape, is mounted on the bed 7, and the automatic workpiece transport device 9 is a gantry-type transport device mounted on the frame structure 10. The automatic workpiece transport device 9 has a configuration in which the traversing table 25 is movable on the frame structure 10 in the lateral direction of the machine body, and the slide base 26 is movable on the traversing table 25 in the forward-backward direction of the machine body.The lifting and lowering arm 27, which moves in the up-down direction, is arranged on a tip end section of the slide base 26, and a robot hand 28 with clamping devices is mounted on a lower end section thereof.

[0014] In such an automatic workpiece transport device 9, the traversing table 25, the carriage base 26, and the lifting and lowering arm 27 are each equipped with servo motors. When the servo motor is driven in any axial direction, its rotary motion is converted into a linear motion in that direction—the Z-axis, Y-axis, or X-axis—via a drive transmission mechanism such as a rack and pinion. Therefore, the workpiece W, gripped by the robot hand 28, is transported by the servo motor's drive control to a predetermined position in any axial direction and moved between that position and the partner device.

[0015] Fig. Figure 3 is a view that conceptually represents a control system for the multifunctional machine tool 1. In the control device 50 for driving the multifunctional machine tool 1, a microprocessor (CPU) 51, ROM 52, RAM 53, non-volatile memory 54, I / O unit 55, and the like are connected via a bus line 58. The CPU 51 performs the overall control of the entire control device, ROM 52 stores the system programs, control parameters, and the like executed by CPU 51, and RAM 53 temporarily stores calculation data and the like.

[0016] The volatile memory 54 contains information necessary for the processing performed by the CPU 51 and stores information such as a machining program and a program for teaching the multifunctional machining center 1. The control device 50 is equipped with a programmable logic controller (PLC) 56, which is connected to the I / O unit 55, and controls the drive sections of various types of machining devices, such as the tool spindle assembly 2 of the multifunctional machining center 1, by means of a sequence program generated in a ladder format. Each function command of the machining program is converted by the sequence program into a required signal and output by the I / O unit 55 to the tool spindle assembly 2 or the like.

[0017] In the multifunctional machining center 1, the machining of the workpiece W is carried out according to the machining program stored in the control unit 50. The workpiece W to be machined is transported from the input storage to the machining position by the automatic workpiece transport device 9. The workpiece, gripped by the robot hand 28, is moved by the drive of the automatic workpiece transport device in the X-axis, Y-axis, and Z-axis directions and is transported to the first workpiece main spindle fixture 3 and the second workpiece main spindle fixture 4. After being fed to the main spindle-side clamping device 11 from each main spindle fixture, a predetermined machining operation is carried out by the first turret fixture 5 and the second turret fixture 6, or a predetermined machining operation is carried out by the tool main spindle fixture 2.

[0018] In the automatic workpiece transport device 9, the drive of each servo motor is stored according to the transport program, and the control of the movement positions of the traversing table 25, the slide base 26, and the lifting and lowering arm 27 is carried out. In the multifunctional machining center 1, the teaching process is performed so that the automatic workpiece transport device 9 can precisely position the workpiece W at the partner device. Therefore, the teaching of the robot hand 28 for the main spindle-side clamping device 11 will be described below using the first workpiece main spindle device 3 as the partner device. The teaching process for the second workpiece main spindle device 4 is also the same.

[0019] In the teaching system configured in the multifunctional processing machine 1, the wireless probe 61 is used as a measuring instrument, so that a detection signal which is in contact with a target object is transmitted to the communication section 57 of the control device 50. Fig. Figure 4 shows a perspective view of the lifting and lowering arm 27 of the automatic workpiece transport device 9. A connecting section 34 is formed at an upper end section of the arm element 33 in the lifting and lowering arm 27, and the rotary motor 35 for adjusting the angle of the robot hand 28 is provided at a lower end section of the arm element 33.

[0020] In the robot hand 28, a pair of robot-side clamping devices 37 and 38 are configured on both the front and rear of the base 36, which can be rotated 180 degrees by the rotary motor 35. During the teaching process, the first of the robot-side clamping devices 37 and 38 grips the probe 61, and the second of the robot-side clamping devices 37 and 38 grips the master workpiece 62 by opening and closing its clamping jaws. The probe 61 and the master workpiece 62 are, for example, equipped with a measuring instrument station on the side of the bearing that holds the workpiece W, and the workpiece W is to be removed from the station by the automatic workpiece transport device 9.

[0021] The master workpiece 62 is transported to the first workpiece main spindle fixture 3, which serves as a target for the learning process, and is gripped by the main spindle-side clamping device 11. After the master workpiece 62 has been moved, the robot hand 28 of the automatic workpiece transport device 9 changes the positions of the robot-side clamping devices 37 and 38 by driving the rotary motor 35, so that the probe 61 is directed towards the partner fixture. Fig. Figure 3 illustrates a teaching state in which the first workpiece main spindle device 3 is used as a partner device, but Fig. Figure 5 is a view that shows the state from above, looking in the direction of the X-axis.

[0022] During the learning process, the servo motor is driven in each axial direction in the automatic workpiece transport device 9, and the measurement is performed in three directions. The tip of the probe 61 is placed against the inner circumferential surface 621 (which can also be an outer circumferential surface 622) of the master workpiece 62, which has a cylindrical shape. When the tip of the probe touches the master workpiece 62, a wireless contact detection signal is transmitted from the probe 61 to the communication section 57. In the control device 50, the rotation angle of the servo motor is determined in accordance with the received contact detection signal, and the coordinate value of the contact position of the probe tip is calculated from the rotation angle. The center position O of the master workpiece 62 is calculated and stored as a coordinate value on an XY plane orthogonal to the Z-axis.

[0023] The center position O of the master workpiece 62, gripped by the main spindle-side clamping device 11, overlaps with the center position of the main spindle of the first workpiece main spindle fixture 3. Therefore, the center position O is stored as a feed position when controlling the workpiece feed W. In this way, centering is achieved by aligning the center of the main spindle of the first workpiece main spindle fixture 3 with the center positions of the robot-side clamping devices 37 and 38, which are configured in the robot hand 28. After the teaching-in of the first workpiece main spindle fixture 3 is complete, the master workpiece 62 is fed to the second workpiece main spindle fixture 4 by the automatic workpiece transport device 9.Then the button 61 is touched in the same way, the center position of the main spindle is calculated from the coordinate value obtained thereby and stored as the feed position when controlling the feed of the workpiece W.

[0024] Furthermore, there may be a case in which the automatic workpiece transport device 9 comes into contact with the machine during operation of the multifunctional machining center 1, thereby causing a mechanical error in the movement position of the robot hand 28. In other words, there may be a case in which the value of the three-dimensional coordinate stored during the teaching process and the actual movement do not match. Even in such a case, the correction is carried out according to the correction program. This is done, for example, in a case in which the workpiece W collides with a clamping jaw of the main spindle-side clamping device 11, resulting in a feed error. After the teaching process described above is complete, the probe 61 and the master workpiece 62 are returned to the measuring instrument station.Therefore, the button 61 or the like is gripped again by the robot hand 28 of the automatic workpiece transport device 9, and the teaching is carried out in the same way to perform the correction of the control value.

[0025] Next is Fig. 6 A view showing a learning state where a workpiece is gripped on one side, viewed from above in the X-axis direction. As in Fig. As shown in Figure 6, if the robot hand 28 grips the workpiece W only with the robot-side clamping device 37 (or 38) on one side of the base 36, a slight inclination in the center line C of the robot-side clamping devices 37 and 38 can occur due to load deviation. Therefore, for example, if the workpiece 63 is gripped on one side by the robot-side clamping device 38, the teaching-in process is performed by gripping the probe 61 with the opposite robot-side clamping device 37. In this case, several workpieces 63 are used, their weights varying from 1 kg to 15 kg in 1 kg increments.

[0026] In the automatic workpiece transport device 9, the tip end of the probe 61 is moved in three directions in the same way as in the following during the gripping of the measuring workpiece 63 against the inner circumferential surface 621 (which can also be an outer circumferential surface 622) of the master workpiece 62. Fig. The case described above is illustrated in Figure 5. The contact detection signal is transmitted by the button 61, and the control device 50 calculates and stores the center position O of the master workpiece 62 as a coordinate value on the XY plane orthogonal to the Z-axis. At this point, if the center line C tilts in accordance with the weight of the measuring workpiece 63, a deviation occurs at the calculated center position O of the master workpiece 62. Therefore, the deviation of the center position O is calculated when the weight of the measuring workpiece 63 changes, and this value is stored as a correction value. For example, the weight of the workpiece W is entered via the touch panel before machining, and the feed control, which is subject to the correction process, is carried out based on this numerical value.

[0027] Subsequently, during the teaching process using the probe 61, the coordinate in the XY plane orthogonal to the main spindle of the first workpiece main spindle device 3 (or second workpiece main spindle device 4) is obtained, but the Z-axis direction, i.e. the depth of the main spindle-side clamping device 11, cannot be measured. Fig. Figure 7 shows a working state of the depth-direction learning process. During depth-direction learning, the workpiece W to be machined is gripped in advance in the state it will be in during machining by the main spindle-side clamping device 11 of the first workpiece-main spindle device 3, which is a target for the learning process. Then, the robot hand 28 of the automatic workpiece transport device 9 moves in the Z-axis direction parallel to the main spindle to grip the workpiece W.

[0028] The robot hand 28 incorporates a contact detection device for recognizing the state in which the workpiece W is gripped. A plate-shaped pusher 42 is provided on a base section of the clamping claw 41 and is moved when the workpiece W contacts it, thus configuring the pickup switch 43 to be pressed. Therefore, during the learning phase, the robot hand 28 moves in the depth direction in the Z-axis direction parallel to the main spindle. The pickup switch 43 is activated by contact with the workpiece W, which is gripped by the main spindle-side clamping device 11, and the drive is stopped based on the contact detection signal. In the control device 50, the coordinate value of the stop position in the Z-axis direction is calculated based on the rotation angle of the servo motor.Then the position at which only the amount by which the push button 42 is moved from the position at which the robot hand 28 is located is calculated and stored as the delivery position in the depth direction.

[0029] According to the present embodiment, an automatic measurement of the delivery position is performed using the contact detection device provided on the robot hand 28, such as the pushbutton 61 and the recording switch 43. The coordinate value for the movement of the robot hand 28 to the delivery position is calculated and stored by the control device based on this measurement. Therefore, a conventional, complex structure is not required, and there can be no difference in accuracy or operating time depending on the operator's skill level. Furthermore, even if a collision occurs during the operation of the multifunctional processing machine 1, it is possible to rectify the situation by performing corrective relearning.

[0030] Although one embodiment of the present invention has been described, the present invention is not limited to this embodiment, and various modifications can be made without departing from the core of the invention. For example, although a gantry-type robot is shown in the above embodiment as an automatic workpiece transport device, it can also be used in an articulated robot, as in the prior art. In the above embodiment, the main spindle is shown as the target for the teaching-in process, but it can also be another device, e.g., the teaching-in process can be for a test and measurement device or similar device for the workpiece being machined. For the teaching-in process, for example, a master workpiece is arranged in each device, and the measurement with the probe 61 is performed on the master workpiece.Furthermore, a different machine tool than the multifunctional machining center 1 can be used, as long as the machine tool has an automatic workpiece transport device. Reference symbol list

[0031] 1: Multifunctional machining center, 2: Tool-main spindle fixture, 3: First workpiece-main spindle fixture, 4: Second workpiece-main spindle fixture, 5: First turret fixture, 6: Second turret fixture, 8: Automatic tool changer, 9: Automatic workpiece transporter, 11: Main spindle-side clamping device, 25: Traveling table, 26: Slide base, 27: Lifting and lowering arm, 28: Robot hand, 36: Base, 37, 38: Robot-side clamping device, 61: Probe, 62: Master workpiece, 63: Measuring workpiece, 50: Control device, 57: Communication section

Claims

[1] A teaching system for an automatic workpiece transport device configured to deliver a workpiece, gripped by a robot-side clamping device configured in a robot hand, to a partner device, the teaching system comprising: a contact detection device, provided in the robot hand and configured to detect contact at a predetermined section with the partner device; and a control device configured to calculate the position of the robot hand during contact based on a contact detection signal from the contact detection device. [2] The teaching system for an automatic workpiece transport device according to claim 1, wherein the contact detection device is a wireless probe that is grasped by the robot hand and is configured to bring a tip end of the probe into contact with a master workpiece arranged in the partner device by driving the automatic workpiece transport device. [3] The teaching system for an automatic workpiece transport device according to claim 2, wherein the partner device is a workpiece main spindle device comprising a main spindle-side clamping device configured to grip and rotate the workpiece, wherein the partner device is configured to bring the tip end of the probe into contact with the master workpiece having a cylindrical shape which is gripped at multiple sections by the main spindle-side clamping device, and to calculate a center position of a main spindle by the control device. [4] The teaching system for an automatic workpiece transport device according to claim 2 or 3, wherein the robot hand is configured such that the robot-side clamping device is configured on both front and rear surfaces of a pivotable base, and while a measuring work workpiece is gripped by a first of the robot-side clamping devices, the robot hand is configured such that it causes the tip end of the probe gripped by a second of the robot-side clamping devices to touch the master workpiece arranged in the partner device. [5] The teaching system for an automatic workpiece transport device according to claim 4, wherein the control device is configured to calculate a deviation amount of a center position of a main spindle based on each measurement by the probe, which are carried out using several measuring workpieces with different weights, and to perform a feed control using the deviation amount of the center position due to a weight change of the measuring workpieces as a correction value. [6] The teaching system for an automatic workpiece transport device according to claim 1, wherein the contact detection device is a pickup switch configured in the robot hand and is configured to detect the presence or absence of a workpiece gripping state by the robot-side clamping device, and the control device is configured to calculate a position of the robot hand by gripping the workpiece arranged on the partner device by the robot-side clamping device.