Machining system with machine tool and robot for attaching and removing a workpiece

Abstract

A machining system comprises a machine tool, a fixture for securing a workpiece, a robot for attaching the workpiece to the fixture, a hand attached to the tip of the robot's arm, and a control device for controlling the machine tool, the robot, and the hand. The fixture includes holding elements for gripping a workpiece and holding element drive motors for driving the holding elements.

Description

Background of the invention 1. Field of the invention

[0001] The present invention relates to a machining system comprising a machine tool and a robot for attaching and removing a workpiece. 2. Description of the related prior art

[0002] For the past few years, a machining system has been used that incorporates a robot for attaching and detaching a workpiece from a machine tool. In this system, the robot brings the workpiece to the machine tool, which then machines it. Once the machine tool has finished machining the workpiece, the robot ejects it.

[0003] Unexamined Japanese patent publication No. 61-125752 discloses that a hydraulic cylinder or rotary cylinder embedded in a chuck device of a machine tool activates an actuator and that the activation of the actuator causes a plurality of bushings to move, so that a workpiece is automatically attached to or detached from the chuck device.

[0004] When a robot attaches or detaches a workpiece, using a control device to operate a clamping device for securing the workpiece to a machine tool enables the construction of an automated operating system that requires no human intervention. However, in conventional machining systems, the clamping device for securing a workpiece to a machine tool is driven hydraulically or pneumatically.

[0005] In hydraulic or pneumatic clamping devices, a piston is provided to drive a claw component, which is then hydraulically or pneumatically actuated. However, in these devices, a workpiece is held or released without fine-tuning of the piston's position. This results in the claw component moving widely and increases operating time. For example, in hydraulic or pneumatic clamping devices, the claw component is open as far as possible to hold the workpiece during a workpiece insertion operation. The robot's movement is stopped while the claw component is being driven, and consequently, the robot requires a waiting period before a workpiece insertion operation can begin.

[0006] DE 10 2014 114 258 A1 discloses the closest prior art. EP 1 693 145 A1 discloses further prior art. Brief description of the invention

[0007] A machining system according to the present invention is provided with a machine tool comprising a clamping device for securing a workpiece. The machining system is provided with a robot for attaching an unmachined workpiece to the clamping device and for removing a machined workpiece from the clamping device, and with a hand attached to a tip end of an arm of the robot. The machining system is provided with a control device for controlling the machine tool, the robot, and the hand. The clamping device comprises a holding element for holding a workpiece and a holding element drive motor for moving the holding element. The holding element moves to hold or release a workpiece.

[0008] In the above invention, the hand can comprise a gripping element for grasping a workpiece and a gripping element drive motor for driving the gripping element.

[0009] In the above invention, the control device can comprise a robot control device for controlling the robot and a machine tool control device for controlling a drive motor for a motion axis in the machine tool. The fastening device can be controlled by the robot control device.

[0010] In the above invention, the fastening device can include a detection device for recognizing the position of the holding element. The control device can calculate a dimension of the portion of the workpiece held by the holding element based on the position of the holding element when it is holding the workpiece.

[0011] In the above invention, the hand can include a detection device for recognizing the drive status of the gripping element. The control device can calculate a dimension of the part of the workpiece gripped by the gripping element based on the drive status of the gripping element when the gripping element grasps the workpiece.

[0012] In the above invention, the control device can correct the relative position of a tool with respect to the workpiece at the time the workpiece is being machined, based on the calculated dimensions of the workpiece. The control device can then control the machine tool so that it machines the workpiece in the corrected relative position.

[0013] In the above invention, when the workpiece is attached to the clamping device and gripped by hand, it can be moved by pressing on the holding element. The control device can change the position and orientation of the robot to follow the movement of the workpiece.

[0014] In the above invention, a detection device can be provided for recognizing the position and orientation of the robot. The control device can calculate the hand position based on the robot's position and orientation. The control device can calculate the workpiece's range of motion as the robot follows the workpiece's movement, based on the hand's position before and after the workpiece is held in the clamping device. The control device can correct the relative position of a tool with respect to the workpiece at the time the workpiece is being machined, based on the workpiece's range of motion. The control device can then control the machine tool so that it machines the workpiece in the corrected relative position.

[0015] The clamping device comprises multiple clamping elements and multiple clamping element drive motors for separately driving the clamping elements. The control device synchronously drives the multiple clamping element drive motors to change the position of the workpiece within the clamping device. Brief description of the drawings Fig. Figure 1 is a schematic perspective view of a machining system equipped with a first fastening device, according to one embodiment. Fig. Figure 2 is a block diagram of a machining system according to one embodiment. Fig. Figure 3 is another schematic perspective view of a machining system equipped with a first fastening device, according to one embodiment. Fig. Figure 4 is an enlarged front view of a first fastening device in which a workpiece is fastened. Fig. Figure 5 is a flowchart that explains the control of a processing system according to one embodiment. Fig. 6 is a schedule that is based on the schedule of Fig. 5 follows. Fig. Figure 7 is a schematic front view illustrating the movement of a workpiece when the workpiece is attached to a first fastening device. Fig. Figure 8 is a schematic perspective view of a second fastening device according to one embodiment. Fig. Figure 9 is another schematic perspective view of a second fastening device according to one embodiment. Fig. Figure 10 is a schematic perspective view of a third fastening device according to one embodiment. Fig. Figure 11 is a perspective view of a workpiece to be machined in a third fastening device. Fig. Figure 12 is a front view of a workpiece to be machined in a third fastening device. Fig. Figure 13 is a schematic front view illustrating a first state when the workpiece is secured in a third fastening device. Fig. Figure 14 is a schematic front view illustrating a second state when the workpiece is secured in a third fastening device. Detailed description

[0016] A machining system according to one embodiment is described with reference to the Fig. 1 to 14 described. The machining system according to the present embodiment is provided with a machine tool for machining a workpiece using a predefined tool and a robot for attaching a workpiece to the machine tool and removing it from it.

[0017] Fig. Figure 1 shows a schematic perspective view of a machining system according to the present embodiment. In a machining system 100 according to the present embodiment, a workpiece 9 to be machined by a machine tool is repositioned by a robot 2. The machine tool according to the present embodiment is a numerically controlled machine tool. Specifically, the machine tool can automatically machine the workpiece 9 based on a pre-defined machining program. The machine tool according to the present embodiment is provided with a first clamping device 4, which is attached to a table 11. The workpiece 9 is clamped to the table 11 via the clamping device 4.

[0018] The machining system 100 is equipped with the robot 2, which attaches the unmachined workpiece 9 to the clamping device 4 and releases the machined workpiece 9 from the clamping device 4. The machining system 100 is equipped with a hand 3, which is attached to the tip end of an arm 21 of the robot 2. The hand 3 is attached to a wrist joint 22 of the arm 21. The robot 2 according to the present embodiment is an articulated robot. The articulated robot according to the present embodiment can freely change the position and orientation of the wrist joint 22 of the arm 21. The robot 2 according to the present embodiment can position the workpiece 9 in the predefined position and orientation.

[0019] The fastening device 4 is provided with a frame 41 which is attached to the table 11. According to the present embodiment, the frame 41 is box-shaped. The frame 41 has a cavity inside. The fastening device 4 is provided with a plurality of retaining elements for holding the workpiece 9. The retaining elements are attached to the frame 41 and comprise fixed retaining elements 47, which are stationary with respect to the frame 41, and movable retaining elements 42, which are movable with respect to the frame 41. According to the present embodiment, the workpiece 9 is designed to have a rectangular planar shape.

[0020] The movable holding elements 42 are arranged such that they, in combination with the stationary holding elements 47, sandwich-like hold the workpiece 9. In the present embodiment, two stationary holding elements 47 and one movable holding element 42 sandwich-like hold the workpiece 9 in one direction of the workpiece 9. Furthermore, one stationary holding element 47 and one movable holding element 42 sandwich-like hold the workpiece 9 in a direction perpendicular to the one direction of the workpiece 9.

[0021] The fastening device 4 comprises first drive motors 43 as holding element drive motors for moving the movable holding elements 42. Guide elements 46 are formed in the movable holding elements 42. The guide elements 46 are inserted into groove sections formed in the frame 41. The groove sections extend in the direction in which the movable holding elements 42 move. The movable holding elements 42 move along the groove sections. The movable holding elements 42 according to the present embodiment are driven by a rack and pinion mechanism. The torque of the first drive motors 43 is amplified by reduction gears 45. The first drive motors 43 are operated such that they cause the movable holding elements 42 to move closer to and away from the workpiece 9, as indicated by arrows 101.

[0022] The hand 3 comprises a hand body 31 and a claw part 32 as a gripping element for grasping a workpiece. The hand body 31 includes a second drive motor as a gripping element drive motor for driving the gripping element. The second drive motor is driven in such a way that the claw part 32 is opened and closed. In a Fig. In the example shown, hand 3 can grasp the workpiece 9 by opening the claw part 32 and can release the workpiece 9 by closing the claw part 32. According to the present embodiment, the workpiece 9 comprises a hole 91 with a substantially circular planar shape. The hole 91 corresponds to a portion that the claw part 32 is to grasp. The claw part 32 engages the workpiece 9 with the inner surface of the hole 91. Note that the hand configuration is not limited to this configuration and any configuration can be used to grasp or release a workpiece.

[0023] Fig. Figure 2 shows a block diagram of a machining system according to the present embodiment. With reference to the Fig. 1 and Fig. In the present embodiment, the machining system 100 is equipped with a machine tool 1 and a control device for controlling the robot 2 and the hand 3. The control device in the present embodiment comprises a machine tool control device 7 for controlling the machine tool 1 and a robot control device 6 for controlling the robot 2 and the hand 3. The machine tool control device 7 and the robot control device 6 are connected by a communication device comprising a communication wire 15. The communication device can perform communication, for example, via Ethernet (registered trademark).

[0024] The machine tool control device 7 comprises a motion control unit 71 and a storage unit 73. The motion control unit 71 controls the drive motors 12, which are provided for motion axes such as the X-axis, Y-axis, Z-axis, etc., in the machine tool 1. In the machine tool 1, the drive motors 12 for the motion axes are driven in such a way that the relative position of the machine tool to the table 11 is changed. Specifically, the machine tool 1 can machine the workpiece 9 while changing the relative position of a tool with respect to the workpiece 9. The storage unit 73 stores, for example, a machining program for machining the workpiece 9.

[0025] The robot control device 6 comprises a motion control unit 61 and a memory unit 63. The motion control unit 61 controls an arm drive motor 23 of the robot 2. The arm drive motor 23 is driven in such a way that the position and orientation of the robot 2 are changed. Furthermore, the motion control unit 61 controls a second drive motor 33 for driving the claw part 32 of the hand 3. The motion control unit 61 sets an angle to which the claw part 32 of the hand 3 is open by controlling the second drive motor 33.

[0026] Furthermore, according to the present embodiment, the robot control device 6 controls the fastening device 4. The motion control unit 61 controls the first drive motors 43 of the fastening device 4. The motion control unit 61 controls the position of the movable holding elements 42. The storage unit 63 stores, for example, a motion program for operating a robot, information detected by a recognition device, and calculated information.

[0027] The robot control device 6 comprises a position detection unit 62. The fastening device 4 comprises a detection device for detecting the position of a retaining element. According to the present embodiment, the fastening device 4 comprises rotation angle detection devices 44 for detecting the rotation angle of the first drive motors 43. In the present embodiment, each rotation angle detection device 44 is located at an end part of each first drive motor 43. The rotation angle detection devices 44 can, for example, consist of an encoder. The rotation angle of the first drive motors 43 can be detected from the output of the rotation angle detection devices 44. The position detection unit 62 can detect the position of the movable retaining elements 42 based on the detected rotation angle.Examples of the position of the movable holding elements 42 include the coordinate value of a predefined point in each movable holding element 42 in a predefined coordinate system of the machine tool.

[0028] The robot 2 comprises a detection device for detecting the position and orientation of the robot 2. According to the present embodiment, the robot 2 comprises a rotation angle detection device 24 for detecting the rotation angle of the arm drive motor 23. The rotation angle of the arm drive motor 23 can be detected from the output of the rotation angle detection device 24. The position detection unit 62 of the robot control device 6 can detect the position and orientation of the robot 2 based on the detected rotation angle.

[0029] The position detection unit 62 can also calculate the position and orientation of hand 3 based on the position and orientation of robot 2.

[0030] The hand 3 includes a detection device for recognizing the drive status of the claw part 32 as a gripping element. The hand 3 of the present embodiment includes a rotation angle detection device 34 for recognizing the rotation angle of the second drive motor 33. The position detection unit 62 of the robot control device 6 can recognize the drive status of the claw part 32, i.e., the opening angle of the claw part 32, based on the output of the rotation angle detection device 34.

[0031] Fig. Figure 1 shows the state before the workpiece 9 is positioned in the clamping device 4. The movable clamping elements 42 are positioned so that they do not come into contact with the workpiece 9, and are located in positions separate from the area in which the workpiece 9 is positioned. In this state, as indicated by arrow 110, the robot 2 positions the workpiece 9 in an area surrounded by the movable clamping elements 42 and the stationary clamping elements 47. The robot 2 positions the workpiece 9 such that it comes into contact with a mounting surface 41a of the frame 41.

[0032] Fig. Figure 3 shows a schematic perspective view when a workpiece is attached to a first fastening device, according to the present embodiment. After the robot 2 has positioned the workpiece 9 on the mounting surface 41a of the frame 41, the movable holding elements 42 move towards the workpiece 9, as indicated by arrow 103.

[0033] When held in the clamping device 4, the workpiece 9 is pressed and moved by the movable holding elements 42 while being held by the hand 3. The robot control device 6 of the present embodiment has a function for changing the position and orientation of the robot 2 according to the movement of the workpiece 9. The robot control device 6 detects the magnitude and direction of an external force applied to the robot 2, e.g., based on an electric current supplied to the arm drive motor 23, and the position and orientation of the robot 2 output by the rotation angle detection device 24. The motion control unit 61 drives the arm drive motor 23, so that the position and orientation of the robot 2 is changed in the direction in which the external force is applied.

[0034] The robot control device 6 enables this function when the movable holding elements 42 press against the workpiece 9. This control allows the movable holding elements 42 to press against the workpiece 9 and enables the workpiece 9 to be brought into close contact with the stationary holding elements 47.

[0035] A majority of the movable holding elements 42 move towards the workpiece 9, and then the movable holding elements 42 and the stationary holding elements 47 sandwich the workpiece 9 in a multiple orientation and hold it. Furthermore, during the period in which the workpiece 9 is held, an electric current is continuously supplied to the first drive motors 43. Thus, during the period in which the workpiece 9 is held, a force is applied to the movable holding elements 42, causing them to move towards the workpiece 9.

[0036] After the clamping device 4 has secured the workpiece 9, the robot 2 retracts. In hand 3, the second drive motor 33 is driven so that the claw part 32 closes. The engagement of the claw part 32 is released. Then, as indicated by arrow 102, the arm 21 of the robot 2 moves away from the workpiece 9, thus separating hand 3 from the workpiece 9.

[0037] Thus, robot 2 can attach the unmachined workpiece 9 to the clamping device 4. Machine tool 1 then machines the workpiece 9. After machining the workpiece 9 is complete, robot 2 releases the machined workpiece 9 from the clamping device 4. In this respect, the workpiece 9 can be released from the clamping device 4 in a process that is the reverse of how it was attached.

[0038] The machine tool control device 7 moves the table 11 so that the clamping device 4 is positioned in a predefined position. The robot control device 6 then closes the claw part 32 of hand 3. The robot control device 6 drives the robot 2 so that the claw part 32 is inserted into the hole 91 of the workpiece 9. The robot control device 6 then opens the claw part 32 of hand 3 to cause hand 3 to grip the workpiece 9. The robot control device 6 then causes the movable holding elements 42 to move away from the workpiece 9 to release the workpiece 9 from the clamping device 4. The workpiece 9 is released from the clamping device 4 while being gripped by the robot 2.

[0039] The robot 2 is then driven to move the workpiece 9 away from the clamping device 4. Furthermore, the robot 2 transports the workpiece 9 to a location where the machined workpiece 9 is positioned.

[0040] In the fastening device 4 according to the present embodiment, the first drive motors 43 can move the movable holding elements 42. A hydraulic or pneumatic fastening device does not set the travel distance of the holding elements. However, the fastening device according to the present embodiment can perform a control operation to position the holding elements in any desired location. When a workpiece is attached to or detached from a fastening device, the fastening device can minimize the travel distance of the holding element. The minimum travel distance of the holding element can be determined, for example, according to the dimensions of a predefined workpiece. Thus, the time required to attach or detach the workpiece can be reduced. Consequently, the time required to machine the workpiece can be reduced.

[0041] The clamping device 4 according to the present embodiment is attached to the table 11 of the machine tool 1, but is controlled by the robot control device 6. This structure allows for a reduction in the time required for communication between the machine tool control device 7 and the robot control device 6. The time required to attach or detach the workpiece 9 from the clamping device 4 can be reduced. For example, the robot control device 6 does not need to send information to the machine tool control device 7 that the workpiece 9 is positioned in a predefined position in the clamping device 4, and consequently, the waiting time of the robot 2 and the machine tool 1 can be reduced.

[0042] Note, for example, that the clamping device can be controlled by the machine tool control device. Alternatively, the control device for controlling the clamping device can be composed of an independent control device. This control device can be configured to facilitate communication between the robot control device and the machine tool control device.

[0043] In the clamping device according to the present embodiment, movable holding elements can be positioned in any desired location, and thus workpieces of different shapes can be machined. The clamping device can secure a variety of workpiece types. For example, the clamping device can secure workpieces of various sizes, and the machine tool can machine workpieces of various sizes. Alternatively, the clamping device can secure a workpiece of any shape that can be held by the holding elements. For example, the clamping device can secure a workpiece with a planar shape where the longitudinal and transverse dimensions differ.

[0044] According to the present embodiment, the fastening device can adjust the compressive forces of the holding elements on a workpiece. In this embodiment, the motion control unit 61 of the robot control device 6 sets the electrical current that is supplied to the first drive motors 43. Increasing the electrical current supplied to the first drive motors 43 can increase the forces required to fasten the workpiece 9. The electrical current to be supplied to the first drive motors 43 can be determined in advance in a motion program of the robot 2, so that it is set based on signals received by the machine tool control device 7.

[0045] For example, when a workpiece is machined by machine tool 1, large forces are applied to the workpiece 9 during heavy cutting operations with a large amount of material removed. The motion control unit 61 increases the electrical current supplied to the first drive motors 43 so that the workpiece 9 can be firmly clamped and machined stably. In contrast, during a finishing operation to refine the surface of the workpiece 9, the workpiece 9 can be deformed if it is clamped with a large force. If the workpiece 9 is deformed, the machining accuracy decreases. During finishing operations, the amount of material removed is small, and consequently, the forces required to hold the workpiece 9 can be reduced.When the finishing operation is carried out, the motion control unit 61 can reduce the electrical current supplied to the first drive motors 43. Reducing the forces required to secure the workpiece 9 can counteract the reduction in machining accuracy for the workpiece 9.

[0046] Meanwhile, the rotation angle detection device 44 is attached to the first drive motors 43 of the mounting device 4. The rotation angle detection device 44 can detect the position of the movable holding elements 42. According to the present embodiment, the robot control device 6 calculates the dimensions of the part of the workpiece 9 held by the holding elements based on the position of the holding elements when the workpiece 9 is held by the holding elements. In the present embodiment, the robot control device 6 calculates the dimensions of the held part of the workpiece 9 based on the position of the movable holding elements 42.

[0047] Furthermore, the hand 3 includes the rotation angle detection device 34 for detecting the drive status of the second drive motor 33. Based on the rotation angle detected by the rotation angle detection device 34, the position of the claw part 32, i.e., the opening angle of the claw part 32, can be calculated. The robot control device 6 calculates the dimensions of the part of the workpiece 9 that is gripped by the claw part 32, based on the position of the claw part 32 when the workpiece 9 is gripped by the claw part 32. For example, if the inner diameter of the hole 91 of the workpiece 9 is large, the claw part 32 is wide open. Conversely, the claw part 32 is not wide open if the inner diameter of the hole 91 is small. Thus, the degree of opening of the claw part 32 is detected in order to calculate the inner diameter of the hole 91.Furthermore, the robot control device 6 can detect the position and orientation of the robot 2 based on the output of the rotation angle detection device 24 of the robot 2.

[0048] Furthermore, the machine tool control device 7 corrects the relative position of a tool with respect to the workpiece 9 when the machine tool 1 is machining the workpiece 9, based on the dimensions of the part of the workpiece 9 held by the clamping device 4, the dimensions of the part of the workpiece 9 gripped by the hand 3, and the position and orientation of the hand 3. The machine tool 1 then machines the workpiece 9 based on the corrected relative position.

[0049] Fig. Figure 4 shows an enlarged front view of a workpiece attached to a first fastening device according to the present embodiment. Fig. 4 The X and Y directions are defined in the machine coordinate system, with a predefined fixed point on the machine tool serving as the starting point. The first drive motors 43 cause two movable holding elements 42 to press against the workpiece 9, as indicated by arrow 103. The workpiece 9 includes dimensional errors.

[0050] At the in Fig. In the example shown, a cutting element 93 is formed at the end of the hole 91 of the workpiece 9. A region 94 encompassing the cutting element 93 is defined. Another component is to be inserted into the cutting element 93 in a subsequent process. In this machining operation, the cutting element 93 is formed in the X-direction such that the region 94 is located substantially in the center of the workpiece 9 in the width direction. A reference point 95 is defined in the region 94 for symmetry. In this example, the reference point 95 deviates from a center point 92 of the hole 91 in the X-direction. However, the machining operation, which allows this deviation, is carried out. In the Y-direction, the cutting element 93 is formed such that a distance HA between the upper part of the cutting element 93 and the upper part of the hole 91 within the region 94 reaches a predefined value.

[0051] Fig. Figure 5 shows a flowchart of the control of a robot system when a cutting operation is carried out according to the present embodiment. With reference to the Fig. 2, Fig. 4 and Fig. In step 121, hand 3 grasps the unmachined workpiece 9. In step 122, a dimension X1 of the part of the workpiece 9 grasped by hand 3 is calculated based on the position information (rotation angle) of the second drive motor 33. The robot control device 6 calculates the dimension X1 of the grasped part based on the opening angle of the claw part 32. A diameter D of the hole 91 corresponds to dimension X1.

[0052] In step 123, the robot control device 6 assesses whether dimension X1 remains within a permissible range. The robot control device 6 includes an assessment unit 64, which performs an assessment operation. Specifically, the assessment unit 64 assesses whether the diameter D of hole 91 is too large or too small. The permissible range for this is determined beforehand. In step 123, if dimension X1 is outside the permissible range, the process proceeds to step 138.

[0053] In step 138, the robot control device 6 determines that the shape of workpiece 9 is defective. Then, in step 139, the robot control device 6 outputs workpiece 9. For example, the robot control device 6 does not execute a control operation to release the grip on workpiece 9 by hand 3. Furthermore, the robot control device 6 controls robot 2 such that workpiece 9 is transported to a storage area for defective goods. In step 123, if dimension X1 remains within the permissible range, the process proceeds to step 124.

[0054] In step 124, the robot 2 positions the workpiece 9 on the mounting surface 41a of the fastening device 4. In step 125, the fastening device 4 moves the movable holding elements 42 to hold the workpiece 9.

[0055] In step 126, the robot control device 6 then calculates a dimension X2 of the part of the workpiece 9 that is held by the holding elements, based on the position information (rotation angle) of the first driven motors 43. In the present embodiment, the robot control device 6 detects the position of the movable holding elements 42 based on the output of the rotation angle detection device 44. Furthermore, a width W of the workpiece 9 is calculated as dimension X2 based on the position of the movable holding elements 42 and the position of the stationary holding elements 47.

[0056] Subsequently, in step 127, the robot control device 6 detects the position and orientation of hand 3 based on the position and orientation of robot 2, which are detected by the rotation angle detection device 24 of robot 2. Furthermore, the robot control device 6 can calculate the position of the center point 92 of hole 91 based on the position and orientation of hand 3.

[0057] In step 128, the robot control device 6 calculates a difference X3 between the part of the workpiece 9 that is gripped by the robot 2 and the part of the workpiece that is attached to the clamping device 4. According to the present embodiment, the robot control device 6 calculates a distance DX between the center point 92 and the surface held in the X-direction by the stationary holding elements 47 as a position difference X3. Furthermore, the robot control device 6 calculates a distance DY between the center point 92 and the surface held in the Y-direction by the stationary holding elements 47 as a position difference X3.

[0058] In step 129, the assessment unit 64 of the robot control device 6 evaluates whether the distance X2 and the position difference X3 remain within their respective permissible ranges. These permissible ranges are determined beforehand. If at least one of the dimensions X2 and the position difference X3 lies outside a permissible range, the process proceeds to step 138. There, it is assessed whether the shape of the workpiece 9 is defective, and in step 139, the workpiece 9 is output. Thus, the shape defects of the workpiece 9 can be verified before machining.

[0059] In step 129, if dimension X2 and position difference X3 remain within their respective permissible ranges, the process proceeds to step 130. In step 130, hand 3 releases workpiece 9. Furthermore, in step 131, robot 2 retracts from workpiece 9. The robot control device 6 sends a signal to the machine tool control device 7, indicating that the clamping of workpiece 9 by clamping device 4 is complete.

[0060] Fig. Figure 6 shows a further flowchart of a control system for a machining system according to the present embodiment. The flowchart in Fig. 6 follows the schedule in Fig. 5. In step 139 in Fig. In step 5, workpiece 9 is rejected because its dimensions X1 and X2 or its positional difference X3 are outside their permissible ranges, and the process then proceeds to step 137. Furthermore, in step 137, the evaluation unit 64 assesses whether an unprocessed workpiece remains. If an unprocessed workpiece remains in step 137, the process returns to step 121. Fig. 5 back and the processing of workpiece 9 is repeated.

[0061] After completing the retraction of robot 2 in step 131 in Fig. 5 the process proceeds to step 132 in Fig. Step 6. In step 132, the correction height of the position when the machine tool performs a machining operation is calculated based on the dimensions X1 and X2 and the position difference X3. The robot control device 6 sends the calculated dimensions X1 and X2 and the position difference X3 to the machine tool control device 7. The machine tool control device 7 is equipped with a correction unit 72. The correction unit 72 corrects the relative position of a tool with respect to the workpiece 9 based on the dimensions X1 and X2 and the position difference X3.

[0062] Fig. Figure 4 shows the reference point 95 of the area 94 when the cutting element 93 is formed in a desired position. The position of the reference point 95 in the X-direction is defined at the midpoint of the width W of the workpiece 9. A length HL of the area 94 in the Y-direction, i.e., the length of the cutting element 93 in the Y-direction, can be defined based on the diameter D of the hole and a predefined length HA. Note that a predefined length can be defined as the width of the area 94.

[0063] The relative position of a tool with respect to the workpiece 9, i.e., a toolpath in each machining operation for the cutting element 93, is predefined by a machining program of the machine tool. Furthermore, the machine tool control device 7 calculates the correction height of the toolpath based on the position of the reference point 95 of the area 94 and the length HL. In the present embodiment, the correction unit 72 calculates the correction height of the tool's position with respect to the workpiece 9 in the X-direction and the correction height of the tool's position with respect to the workpiece 9 in the Y-direction. The correction unit 72 then generates the corrected toolpath based on the correction height.

[0064] In step 133, machine tool 1 then machines workpiece 9 using the corrected toolpath. The toolpath is corrected based on the individual deviations of workpiece 9, and accordingly, machining operations can be performed for the desired positions of workpiece 9. Specifically, machine tool 1 can machine workpiece 9 while correcting form errors. When the machining of workpiece 9 is complete, the machine tool control unit 7 sends a signal to the robot control unit 6 indicating that the machining is complete.

[0065] In step 134, the robot control device 6 calculates the position and orientation of the robot 2, which grips the workpiece 9 using hand 3. The robot control device 6 can calculate the position of the machined hole 91 of the workpiece 9 based on the dimensions X1 and X2 and the position difference X3. For example, the position of the center point 92 of the hole 91 can be calculated. Note that the robot control device 6 can store the position and orientation of the robot 2 in the memory unit 63 when the grip on the workpiece 9 is released. The robot control device 6 can, for example, determine the position and orientation of the robot 2 when the workpiece 9 is gripped based on the stored position and orientation. This control allows the robot 2 to grip the workpiece 9 while form corrections are being made to the workpiece 9.

[0066] Furthermore, in step 134, the robot control device 6 can calculate the dimensions of the gripped part of the workpiece 9 based on the dimensions X1 and X2 and the position difference X3. For example, the robot control device 6 can calculate the dimensions of the machined hole 91. Additionally, the robot control device 6 can calculate the opening angle of the claw part 32 of hand 3. This control enables hand 3 to reliably grip the machined workpiece 9.

[0067] In step 135, the robot control device 6 then controls the position and orientation of the robot 2 so that hand 3 can grasp the workpiece 9. Hand 3 then grasps the workpiece 9. In step 136, the robot 2 transports the workpiece 9 to a predefined location.

[0068] The robot control device 6 then assesses in step 137 whether an unprocessed workpiece remains. If an unprocessed workpiece is still present in step 137, the process returns to step 121. Fig. 5 returns and the machining of workpiece 9 is repeated. Thus, the machining system 100, according to the present embodiment, can repeat the machining of workpiece 9. A multiple of workpieces can be machined automatically.

[0069] In the above embodiment, the control device performs an assessment of the shape of the workpiece 9, a correction of the toolpath of the machine tool, and a correction of the position and orientation of the robot 2 when the workpiece 9 is detached, based on the dimensions X1 and X2 and the position difference X3. The control device is not limited to this type and can perform an assessment or correction using some of the dimensions X1 and X2 and the position difference X3.

[0070] With reference to Fig. 4 In the present embodiment, the robot control device 6 calculates the dimensions of the part of the workpiece 9 that is held by the holding elements, based on the position of the movable holding elements 42. In particular, the robot control device 6 calculates the width W of the workpiece 9. The calculation of the dimensions of the workpiece 9 is not limited to this type of calculation and can be performed based on the range of motion of the workpiece 9 when the workpiece 9 is held by the movable holding elements 42.

[0071] Fig. Figure 7 shows a schematic front view of a workpiece when it is secured by the clamping device. When the workpiece 9 is positioned on the mounting surface 41a of the frame 41, the robot 2 positions the workpiece 9 within an area surrounded by the movable clamping elements 42 and the fixed clamping elements 47. The workpiece 9 is positioned, for example, at position 90a. In this position, a gap is formed between the workpiece 9 and the movable clamping elements 42, and between the workpiece 9 and the fixed clamping elements 47. Furthermore, the robot control device 6 moves the movable clamping elements 42, as indicated by arrow 103, so that the workpiece 9 is brought into close contact with the fixed clamping elements 47. The robot 2 is driven while following the external forces as described above.

[0072] The workpiece 9 is positioned at position 90b in close contact with the stationary holding elements 47. A center point 92a of the hole 91 of the workpiece 9 moves in the direction indicated by an arrow 106. The center point then moves to a position indicated by a center point 92b of the hole 91.

[0073] The robot control device 6 can calculate the position of the center point 92a of hole 91 and the position of the center point 92b based on the position information of hand 3 when the workpiece 9 is attached. Specifically, the robot control device 6 can calculate the position of hand 3 before and after the workpiece 9 is held by the clamping device 4. Furthermore, the robot control device 6 can calculate the direction and the range of motion, indicated by arrow 106, of the center point 92 of hole 91. This range of motion includes the range of motion in the X direction and the range of motion in the Y direction.

[0074] The basic dimensions, which form the basis for the dimensions of workpiece 9, and the basic range of motion of the center point 92 of hole 91 for a workpiece with these basic dimensions, are determined in advance. Furthermore, the robot control device 6 can correct the dimensions of workpiece 9 based on the basic range of motion and the actual range of motion. For example, if the dimensions of workpiece 9 are larger than the basic dimensions, the range of motion indicated by arrow 106 decreases. Conversely, if the dimensions of workpiece 9 are smaller than the basic dimensions, the range of motion indicated by arrow 106 increases. Thus, the robot control device 6 can calculate predefined dimensions of workpiece 9 based on the actually detected range of motion.For example, the robot control device 6 can calculate the distance from the stationary holding elements 47 to the center point 92 of the hole 91 based on the range of motion. In particular, the position of the center point 92 of the hole 91 in the Y-direction can be calculated based on the range of motion in the Y-direction.

[0075] Thus, the robot control device 6 can, for example, calculate the dimensions of the workpiece 9 based on the range of motion of the workpiece 9 when the robot 2 follows the workpiece 9 to hold it. Furthermore, the correction unit 72 of the machine tool control device 7 corrects the relative position of a tool with respect to the workpiece 9 when a machining operation is performed. For example, the correction unit 72 can determine the position of the reference point 95 in the Y-direction in the area 94 of the cutting part 93 based on the position of the center point 92 of the hole 91 in the Y-direction. Furthermore, the correction unit 72 can correct the relative position of a tool with respect to the workpiece 9 for cutting the cutting part 93. The motion control unit 71 can control the machine tool 1 so that the workpiece 9 can be machined in the corrected relative position.

[0076] Fig. Figure 8 shows a schematic perspective view of a second fastening device according to the present embodiment. Similar to the first fastening device 4, a second fastening device 5 is provided with movable retaining elements 42 and fixed retaining elements 47, which can hold the side surfaces of the workpiece 9. Furthermore, the second fastening device 5 is provided with a movable retaining element 53 for holding the top surface of the workpiece 9. The movable retaining element 53 presses against the workpiece 9 at one end (first end). The frame 41 includes a projection 54 that extends from the mounting surface 41a. The movable retaining element 53 is rotatably supported by the projection 54.

[0077] The second mounting device 5 is equipped with a first drive motor 48 for driving the movable holding element 53. The first drive motor 48 is attached to a projection 50 that extends from a side surface of the frame 41. A rotation angle detection device 49 for detecting the rotation angle of the first drive motor 48 is attached to the first drive motor 48. The first drive motor 48 is controlled by the robot control device 6.

[0078] A rotating element 51, which rotates together with the output shaft of the first drive motor 48, is attached to the output shaft. One end part of a connecting element 52 is connected to the rotating element 51. The other end part of the connecting element 52 is designed to push the other end part (the second end part) of the movable retaining element 53.

[0079] Fig. Figure 9 shows a schematic perspective view of a workpiece attached to a second fastening device according to the present embodiment. With reference to the Fig. 8 and Fig. In 9, an end part of the movable holding element 53 is moved by a mechanism comprising the rotary element 51 and the connecting element 52 in the direction indicated by arrow 107. The first drive motor 48 is driven to rotate the rotary element 51. The rotary element 51 rotates to move the connecting element 52. Subsequently, the movable holding element 53, supported by the projection 54, is rotated to press down on the top of the workpiece 9. The movable holding element 53 presses down on the workpiece 9 to hold it in place. Even while the workpiece 9 is held, electrical current continues to be supplied to the first drive motor 48 to cause the movable holding element 53 to press down on the workpiece 9, as indicated by arrow 108.

[0080] When workpiece 9 is being machined, the part of the workpiece on which the holding element exerts pressure can be machined. For example, with reference to Fig. In the second fastening device 5 according to the present embodiment, the holding element can be moved while the workpiece 9 is being machined. The holding status of some of the holding elements can be temporarily released.

[0081] For example, if a recessed area is formed in the region of the workpiece 9 with which the movable holding element 53 is in contact, the robot control device 6 drives the first drive motor 48 to cause the movable holding element 53 to move away from the workpiece 9. The movable holding element 53 moves away from the workpiece 9 so that the machine tool 1 can machine the region of the workpiece 9 with which the movable holding element 53 is in contact. After the machining operation in the machine tool is completed, the robot control device 6 drives the first drive motor 48 to cause the movable holding element 53 to hold the workpiece 9.

[0082] Thus, the movable holding element 53 in the machining system equipped with the second clamping device can move during the machining operation of the workpiece 9. To machine the area of ​​the workpiece gripped by the movable holding element, it is not necessary to change the direction of the clamped workpiece or use another clamping device, and therefore machining operations can be performed continuously in the same clamping device. Consequently, the machining time for a workpiece can be reduced. Furthermore, the method for holding a workpiece in a third clamping device can be modified during machining operations. For example, the portion of the workpiece to be held can be changed depending on the portion of the workpiece being machined.

[0083] The holding element that can move during a machining operation is not limited to the holding element used to press down on the top of a workpiece; any holding element can be moved. For example, with reference to Fig. 9 During a machining operation, it is possible to cause the movable holding elements 42, which hold the side surfaces of the workpiece 9, to move away from the workpiece 9.

[0084] Note that the movable holding element can press down on the workpiece after it has moved away from the workpiece and the portion of the workpiece from which it moved has been machined. The motion control unit of the robot control device can then correct the dimensions of the workpiece portion using the correction control described above. Furthermore, the motion control unit can drive the movable holding element according to these corrected workpiece dimensions.

[0085] The other configurations, operations and effects of the machining system equipped with the second fastening device are similar to those of the machining system equipped with the first fastening device.

[0086] Fig. Figure 10 shows a schematic perspective view of a third fastening device according to the present embodiment. The third fastening device 8 according to the present embodiment is positioned in a lathe as a machine tool. The third fastening device 8 is a chuck for holding a workpiece 10. Fig. Figure 10 shows the status of the workpiece 10 to be machined, which is attached to the third clamping device 8. Note that, similar to the machine tool mentioned above, the workpiece 10 is attached to or detached from the clamping device 8 by a robot. In the lathe according to the present embodiment, the workpiece 10 is attached to or detached from the clamping device 8 by moving the workpiece 10 in the direction in which the axis of rotation 99 extends.

[0087] The mounting device 8 is provided with a base element 81, which is shaped like a disc. The lathe is equipped with a base element drive motor for rotating the base element 81 about the axis of rotation 99. The base element drive motor is driven such that the base element 81 is rotated in the direction indicated by an arrow 109. In the lathe according to the present embodiment, the workpiece 10 rotates about the axis of rotation 99 during machining without changing its position. The lathe is equipped with a cutting tool that serves as the tool. The lathe according to the present embodiment includes drive motors for moving the cutting tool along predefined axes of motion. The drive motors for the axes of motion are driven such that the relative position of the machine tool to the base element 81 is changed.Specifically, the drive motors for the motion axes are driven in such a way that the relative position of the machine tool to the workpiece 10 is changed. Similar to the machine tool mentioned above, the motion control unit of the machine tool control device controls the drive motors for the respective motion axes or the base element drive motor.

[0088] The fastening device 8 is provided with a movable holding element 82, which serves as a chuck claw for holding the workpiece 10. A plurality of movable holding elements 82 are arranged in the fastening device 8. The movable holding elements 82 move along guide sections 83, which are grooves formed in the base element 81. The movable holding elements 82 move in radial directions of the base element 81, as indicated by arrows 101. The workpiece 10 is secured by an intermediate element 84. The intermediate element 84 is held by the movable holding elements 82. Specifically, the workpiece 10 is held by the movable holding elements 82 via the intermediate element 84.

[0089] Fig. Figure 11 shows a perspective view of a workpiece held by the third fastening device. Fig. Figure 12 shows a front view of a workpiece held by the third fastening device. Referring to the Fig. 11 and Fig. 12 is a workpiece 10, a camshaft of a predefined device. The workpiece 10 comprises a rod-like shaft 96 and circular cams 97 with a circular cross-section. Each circular cam 97 is arranged such that it is eccentric with respect to a central axis 98 of the shaft 96.

[0090] With reference to Fig. 10 The third fastening device 8 according to the present embodiment comprises first drive motors as holding element drive motors for driving the movable holding elements 82. The fastening device 8 comprises a plurality of first drive motors corresponding to the movable holding elements 82. Each of the first drive motors drives the corresponding movable holding element 82. Furthermore, the first drive motors are controlled separately by the motion control unit 61 of the robot control device 6. Specifically, each of the first drive motors controls the position of the corresponding movable holding element 82.

[0091] Furthermore, the control device is configured to synchronously drive a plurality of the first drive motors to change the position of the workpiece 10 in the clamping device 8. In the clamping device 8, the relative position of the intermediate element 84 with respect to the base element 81, i.e., the relative position of the workpiece 10 with respect to the base element 81, can be changed while the workpiece 10 is being machined. A plurality of the movable holding elements 82 are moved simultaneously to change the position of the workpiece 10.

[0092] Fig. Figure 13 shows a schematic front view of a third fastening device and the workpiece, showing a first state of the workpiece to be machined. Fig. Figure 13 is a view illustrating the state in which the surface of the shaft 96 is cut. The workpiece 10 is positioned such that the central axis 98 of the shaft 96 coincides with the axis of rotation 99 of the base element 81. In the first state, a majority of the movable retaining elements 82 are arranged such that their distances from the axis of rotation 99 in the radial direction of the base element 81 are equal. The workpiece 10 rotates about the central axis of the shaft 96 and can therefore be machined so that the shaft 96 has a circular cut.

[0093] Fig. Figure 14 shows a schematic front view of the third clamping device and the workpiece, illustrating a second state of the workpiece to be machined. After completion of the machining of shaft 96, the motion control unit 61 of the robot control device 6 synchronously drives the first drive motors. The movable holding element 82 moves separately. The motion control unit 61 controls a plurality of the first drive motors to translate the workpiece 10, while a plurality of the movable holding elements 82 maintain the state in which the workpiece 10 is held.

[0094] In the second state, the movable retaining elements 82 are arranged such that the central axis of one of the circular cams 97 coincides with the axis of rotation 99 of the base element 81. The intermediate element 84 in Fig. 14 is arranged in a position higher than that of the one in Fig. The first status shown is 13.

[0095] In the second state, the central axis of one of the circular cams 97 coincides with the axis of rotation 99 of the base element 81. Thus, the surface of the circular cam 97 can be machined so that the circular cam 97 has a circular cut.

[0096] In the machining system equipped with the third clamping device, the control unit synchronously drives multiple clamping element drive motors to change the position of a workpiece within the clamping device. This machining system can change the workpiece's position while it is being machined. The third clamping device eliminates the need to reposition the intermediate element or to reposition clamping elements with different shapes when machining multiple parts with varying center axes, thus enabling continuous machining. Consequently, the machining time for a single workpiece can be reduced.

[0097] The other configurations, operations, and effects of the machining system equipped with the third fastening device are similar to those of the machining system equipped with the first fastening device.

[0098] The present invention can provide a machining system comprising a machine tool and a robot for attaching and detaching a workpiece to the machine tool, and which can reduce the time of attaching and detaching the workpiece.

[0099] The sequence of steps in each of the above control systems can be changed accordingly, as long as the function and operation remain the same. The above embodiments can be combined as appropriate.

[0100] In the drawings above, the same or corresponding sections are identified by the same reference numerals. It should be noted that the embodiments described above are examples and do not limit the invention. Furthermore, the embodiments include modifications of aspects described in the claims.

Claims

[1] Processing system (100) comprising: a machine tool (1) comprising a fastening device (8) for fastening a workpiece (10); a robot (2) for attaching an unmachined workpiece (10) to the fastening device (8) and for removing a machined workpiece (10) from the fastening device (8); a hand (3) attached to a pointed end of an arm (21) of the robot (2); and a control device (6, 7) for controlling the machine tool (1), the robot (2) and the hand (3); wherein the fastening device (8) comprises a holding element (82) for holding a workpiece (10) and a holding element drive motor (43) for moving the holding element (82), wherein the holding element (82) moves to hold or release a workpiece (10); characterized by , that the fastening device (8) comprises a plurality of retaining elements (82) and a plurality of retaining element drive motors (43) for separately driving the retaining elements (82), and the control device (6, 7) synchronously drives the majority of holding element drive motors (43) to change the position of the workpiece (10) in the fastening device (8). [2] Machining system (100) according to claim 1, wherein the hand (3) comprises a gripping element (32) for gripping the workpiece (10) and a gripping element drive motor (33) for driving the gripping element (32). [3] Machining system (100) according to claim 1 or 2, wherein: the control device (6, 7) comprises a robot control device (6) for controlling the robot (2) and a machine tool control device (7) for controlling a drive motor for a motion axis in the machine tool (1), and the fastening device (8) is controlled by the robot control device (6). [4] Machining system (100) according to one of claims 1 to 3, wherein the fastening device (8) comprises a detection device (44) for detecting a position of the retaining element (82), and The control device (6, 7) calculates a dimension of the part of the workpiece (10) that is held by the holding element (82) based on a position of the holding element (82) when the holding element (82) holds a workpiece (10). [5] Machining system (100) according to claim 2, wherein: the hand (3) includes a detection device (34) for detecting a drive status of the gripping element (32), and The control device (6, 7) calculates a dimension of the part of the workpiece (10) that is gripped by the gripping element (32) based on a drive status of the gripping element (32) when the gripping element (32) grips the workpiece (10). [6] Machining system (100) according to claim 4 or 5, wherein: The control device (6, 7) corrects a relative position of a tool with respect to the workpiece (10) at the time when the workpiece (10) is being machined, based on a calculated dimension of the workpiece (10), and controls the machine tool (1) so that it machines the workpiece (10) in the corrected relative position. [7] Machining system (100) according to any one of claims 1 to 6, wherein the workpiece (10) is moved by being pressed by the holding element (82) when the workpiece (10) is secured in the fastening device (8) while being gripped by the hand (3), and the control device (6, 7) changes the position and orientation of the robot (2) to follow a movement of the workpiece (10). [8] Machining system (100) according to claim 7, comprising a detection device (24) for detecting the position and orientation of the robot (2), wherein: The control device (6, 7) calculates a position of the hand (3) based on the position and orientation of the robot (2), calculates a movement range of the workpiece (10) when the robot (2) follows the movement of the workpiece (10) based on the position of the hand (3) before and after holding the workpiece (10) in the clamping device (8), corrects a relative position of the tool with respect to the workpiece (10) at the time when the workpiece (10) is being machined based on the movement range of the workpiece (10) and controls the machine tool (1) so that it controls the workpiece (10) in a corrected relative position.

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