Jig arrangement method, transfer device, and jig

Abstract

This invention provides a jig placement method that uses a transfer device to properly position jigs on a machine tool, thereby correctly fixing the workpiece, ensuring accurate machining, and improving work efficiency through automation. [Solution] The transfer device 1, which holds the jig 75, directs the jig 75 toward the contact surface of the workpiece 90, which is positioned on the workpiece fixing section 71, so that the jig 75 is in at least line contact with the contact surface of the workpiece 90. This allows the jig 75 to be properly positioned relative to the workpiece 90, correctly fixing the workpiece 90 and enabling accurate machining of the workpiece 90. Furthermore, since the transfer device 1 can easily automate the jig positioning, structural changes to the machine tool 70 are unnecessary, the complexity and size of the machine tool itself can be avoided, and the costs associated with introducing and using the machine tool 70 can be reduced.

Description

Technical Field

[0001] The present invention relates to a jig arrangement method for arranging a jig for fixing a workpiece to a machine tool, and particularly to a method for arranging the jig along the workpiece fixing portion and the workpiece of the machine tool.

Background Art

[0002] A surface grinding machine has the feature of being able to grind the outer surface of a workpiece and form a highly accurate plane. In the precision machining of metal workpieces using a surface grinding machine, a skilled technician places a workpiece such as a rectangular parallelepiped at an appropriate position on the table of the grinding machine based on experience, and performs the work of fixing it using a jig before processing. In order to improve the efficiency of the machining operation on such a surface grinding machine, automation is required for the placement (setting) of the workpiece and the jig on the table, which has been performed manually.

[0003] In recent years, various proposals have been made as automation techniques. For example, the table that supports the workpiece is made rotatable, and a plurality of workpiece placement positions on the table are set, and the positions away from the grinding wheel are respectively used as the loading position for the unprocessed workpiece and the unloading position for the processed workpiece. Then, when the table is rotated, the unprocessed workpiece at the loading position reaches the processing position, and the processed workpiece at the processing position reaches the unloading position.

[0004] Thereby, during the machining of the workpiece by the grinding wheel, the unprocessed workpiece at the loading position on the table can be transferred and placed by a predetermined conveying means, and the processed workpiece can be unloaded from the unloading position on the table by a predetermined conveying means. After the machining of the workpiece is completed, the table is rotated to newly place the unprocessed workpiece at the loading position at the processing position and move the processed workpiece from the processing position to the unloading position. In this way, the attachment and detachment of the workpiece to and from the table can be automatically performed in parallel with the machining of the workpiece, and the automation of the setting of the workpiece on the table, which has relied on manual work, can be achieved. One example of a method for automatically positioning and fixing a workpiece on the table in such a conventional surface grinding machine is disclosed in Japanese Patent Publication No. 2-185357. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2-185357 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Conventional methods for automating workpiece placement in surface grinding machines typically involve the method exemplified in the aforementioned patent document. In conventional surface grinders described in patent documents, the table that holds the workpiece is replaced with an index table that rotates at a constant angle and a rotary table that holds the workpiece. As a result, the structure becomes more complex and larger compared to surface grinders with previous types of tables, leading to higher costs.

[0007] Furthermore, according to patent documents, the process of placing workpieces on a table is performed by work loaders or robots without the use of special jigs. In this case, the workpieces are not placed on the table with the same level of care as when a skilled worker manually places them while ensuring they are in contact with each other. As a result, it is possible that the workpieces may tilt relative to the table when they are placed on it. If the workpieces are temporarily fixed in a tilted position relative to the table and machining is performed, not only will the workpieces not be machined correctly, but there is also a risk of damage to the workpieces, grinding wheels, and tables.

[0008] The disclosure of this invention is made to solve the aforementioned problems. Specifically, the objective is to provide a jig placement method, a transfer device used therefor, and a jig that enable the proper placement of a jig on a machine tool using a transfer device, correct fixing of the workpiece, accurate execution of machining, and improved work efficiency through automation. [Means for solving the problem]

[0009] The jig placement method disclosed in the present invention includes at least a jig placement step of moving a jig for fixing a workpiece with a predetermined transfer device to a workpiece fixing part of a machine tool that fixes a workpiece to be processed, and placing the jig on the workpiece fixing part, wherein the jig is a three-dimensional object having a bottom surface and a protruding contact portion that protrudes in a direction parallel to the bottom surface, the workpiece fixing part has a first reference surface and a second reference surface perpendicular to the first reference surface, and prior to the jig placement step, the workpiece is arranged in close contact with the second reference surface, and in the jig placement step, the position and orientation of the jig are adjusted with the transfer device while the bottom surface of the jig is in surface contact with the first reference surface of the workpiece fixing part, so that at least the tip portion of the contact portion is in contact with the contact surface of the workpiece arranged on the workpiece fixing part that is opposite to the contact surface with the second reference surface.

[0010] As described above, according to the disclosure of the present invention, a transfer device holding a jig directs the jig toward the contact surface of the workpiece that is positioned on the workpiece fixing part, so that the contact part of the jig is in contact with the contact surface. This allows the jig to be properly positioned relative to the workpiece, the workpiece to be correctly fixed, and the workpiece to be processed accurately. Furthermore, since the automation of jig positioning can be easily achieved with the transfer device, structural changes to the machine tool are unnecessary, the complexity and size of the machine tool itself can be avoided, and the costs associated with introducing and using the machine tool can be reduced. [Brief explanation of the drawing]

[0011] [Figure 1]Figure 1(a) is a front view of a machine tool to which the jig placement method according to one embodiment of the present invention is applied, and Figure 1(b) is a perspective view of a transfer device used in the jig placement method according to one embodiment of the present invention. [Figure 2] Figure 2(a) is a perspective view of a jig used in a jig placement method according to one embodiment of the present invention, and Figure 2(b) is an enlarged view of the contact portion of the jig used in a jig placement method according to one embodiment of the present invention. [Figure 3] Figure 3(a) is an explanatory diagram of the initial state of gripping the jig by the fingers of the hand portion in a transfer device used in a jig placement method according to one embodiment of the present invention, and Figure 3(b) is an explanatory diagram of the state of gripping the jig by the fingers of the hand portion in a transfer device used in a jig placement method according to one embodiment of the present invention. [Figure 4] Figure 4(a) is an explanatory diagram in the x-axis direction showing the initial state of contact between the jig and the first reference surface in a jig placement method according to one embodiment of the present invention; Figure 4(b) is an explanatory diagram in the x-axis direction showing the state of surface contact of the jig with the first reference surface in a jig placement method according to one embodiment of the present invention; and Figure 4(c) is an explanatory diagram in the x-axis direction showing the state of excessive tilting of the jig in a jig placement method according to one embodiment of the present invention. [Figure 5] Figure 5(a) is an explanatory diagram in the z-axis direction showing the initial state of contact between the jig and the workpiece contact surface in a jig placement method according to one embodiment of the present invention; Figure 5(b) is an explanatory diagram in the z-axis direction showing the surface contact state of the jig with the workpiece contact surface in a jig placement method according to one embodiment of the present invention; and Figure 5(c) is an explanatory diagram in the z-axis direction showing the over-tilting state of the jig in a jig placement method according to one embodiment of the present invention. [Figure 6] This is a flowchart of the first half of the jig placement process in a jig placement method according to one embodiment of the present invention. [Figure 7] This is a flowchart of the latter half of the jig placement process in a jig placement method according to one embodiment of the present invention. [Figure 8] Figure 8(a) is an explanatory diagram of the contact state between the jig and the workpiece contact surface in a jig placement method according to one embodiment of the present invention, and Figure 8(b) is an explanatory diagram of the completed jig placement state in a jig placement method according to one embodiment of the present invention. [Figure 9]FIG. 9(a) is an explanatory diagram of the start state of releasing the jig gripping by the finger portion of the hand portion in the jig arrangement method according to an embodiment of the present invention, and FIG. 9(b) is an explanatory diagram of the state of releasing the jig gripping by the finger portion of the hand portion in the jig arrangement method according to an embodiment of the present invention. [Figure 10] FIG. 10(a) is an explanatory diagram of the approach state of the jig to the reference plane in the x-axis direction view in the jig arrangement method according to another embodiment of the present invention, FIG. 10(b) is an explanatory diagram of the initial contact state between the jig and the reference plane in the x-axis direction view in the jig arrangement method according to another embodiment of the present invention, and FIG. 10(c) is an explanatory diagram of the surface contact state of the jig to the reference plane in the x-axis direction view in the jig arrangement method according to another embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, a jig arrangement method according to an embodiment of the present invention will be described based on FIGS. 1 to 9. In this embodiment, an example of a method for arranging a jig for fixing a workpiece on a surface grinding machine as a machine tool will be described. In FIG. 1, illustrations of the reference jigs 73, 74, and the jig 75, which will be described later, are omitted.

[0013] In each figure, the jig arrangement method according to this embodiment is to hold and move the workpiece fixing jig 75 by the transfer device 1 with respect to the workpiece fixing portion 71 that fixes the workpiece 90 to be processed in the machine tool 70, and arrange the jig 75 on the workpiece fixing portion 71.

[0014] The machine tool 70, which is a surface grinding machine, has a table 71a capable of fixing the workpiece 90 to be ground by a magnetic chuck 72 as a main part of the workpiece fixing portion 71. A plurality of reference planes for workpiece positioning are provided on the workpiece fixing portion 71. One of them, the first reference plane �2a, is the upper surface of the table 71a (the upper surface of the magnetic chuck 72).

[0015] Also, a reference jig 73, a reference jig 74, and a lower jig 77 are fixed to the upper surface of a table 71a forming the work fixing portion 71 (the upper surface of the magnetic chuck 72). Among these jigs fixed to the upper surface of the table, a side surface of the reference jig 73 that forms a right angle with the upper surface of the table 71a (the upper surface of the magnetic chuck 72) is defined as a second reference surface 73a. By bringing each corresponding surface of the work 90 into surface contact with these reference jigs 73, 74, and lower jig 77, the work 90 is disposed in the work fixing portion 71.

[0016] The jig 75 disposed in the work fixing portion 71 by the jig arrangement method according to the present embodiment is formed as a three-dimensional body having a bottom surface 75a and a protruding contact portion 75b that protrudes in a direction parallel to the bottom surface 75a at a position away from the bottom surface 75a. Specifically, the jig 75 has a structure in which one surface of a rectangular parallelepiped or a cube is used as the bottom surface 75a, and the contact portion 75b is provided in a state of protruding from a predetermined surface that becomes a side surface with respect to the bottom surface 75a.

[0017] The contact portion 75b has a semi-circular cross-sectional shape that forms a right angle with the bottom surface 75a, and is formed as a semi-cylindrical surface-shaped curved surface that is continuous in a direction parallel to the bottom surface 75a. The contact surface 75c, where the chord of the semi-circular cross-section forms a right angle with the bottom surface 75a, is provided at two positions at the tip portion. Thus, the contact portion 75b has a shape in which the contact surface 75c at the tip portion can be line-contacted with a line parallel to the bottom surface 75a with respect to a virtual plane that forms a right angle with the bottom surface 75a, and can be line-contacted with the corresponding work 90. Note that the contact portion 75b is provided in upper and lower two stages with different distances of the contact surface 75c from the bottom surface 75a. However, it is not limited to this, and only one contact surface may be provided.

[0018] In the jig placement method according to this embodiment, in the step of placing the jig 75 on the workpiece fixing section 71 (jig placement step), the transfer device 1 brings the bottom surface 75a of the jig 75 into surface contact with the first reference surface 72a provided on the workpiece fixing section 71. Furthermore, the transfer device 1 brings the contact portion 75b of the jig 75 into contact with the contacted surface 95 of the workpiece 90 already placed on the workpiece fixing section 71. More specifically, the contact portion 75b (contact surface 75c) of the jig 75 is brought into line contact with the contacted surface 95 of the workpiece 90, which is placed in contact with the second reference surface 73a of the workpiece fixing section 71, on the side opposite to the surface in contact with the second reference surface 73a. This allows the jig 75 to be positioned on the workpiece fixing part 71, enabling the workpiece 90 to be clamped in a way that prevents it from easily moving, and the final fixing state to be achieved without any problems.

[0019] The transfer device 1 used in the jig placement method according to this embodiment comprises a robot arm 10, a force sensor 20, a hand unit 30, and a control unit 40. The robot arm 10 has multiple joints, and the hand portion 30 and the end portion containing the force sensor 20 are adjustable in position and orientation in at least 6 degrees of freedom (3 axial directions: x, y, and z axes, and 3 rotational directions: around the x, y, and z axes). This robot arm 10 is a known vertical articulated robot device having 6 or more degrees of freedom, and a detailed explanation is omitted.

[0020] The robot arm 10, together with the hand portion 30, forms a transfer mechanism and operates based on control by the control unit 40. The robot arm 10 positions the workpiece 90 held by the hand portion 30 at its tip so as to align with the reference surfaces 72a and 73a of the workpiece fixing portion 71, and also performs a jig placement process in which a jig 75 is placed on the workpiece fixing portion 71 and brought into contact with the workpiece 90. Furthermore, a robot arm with fewer degrees of freedom is acceptable, as long as it has the necessary degrees of freedom to move the workpiece along a reference plane or to move the jig into contact with the workpiece.

[0021] The force sensor 20 is interposed between the tip of the robot arm 10 and the hand portion 30, and is capable of detecting the force and moment generated in the jig 75 held by the hand portion 30. The force sensor 20 has a mounting mechanism for the tip of the robot arm 10 on one end face, and is attached to the tip of the robot arm 10 on this end face side. On the other hand, the force sensor 20 has a mounting mechanism for the hand portion 30 on the other end face opposite to the first end face, and the hand portion 30 is attached to this other end face side.

[0022] The force sensor 20 is a 6-axis force sensor capable of detecting forces in the orthogonal three-axis direction (x-axis, y-axis, z-axis) and moments around the orthogonal three axes, which are applied relative to one end face side. The mechanism by which the force sensor 20 can detect forces in the orthogonal three-axis direction and moments around the orthogonal three axes is the same as that of known force sensors (6-axis force sensors), and therefore a detailed explanation is omitted.

[0023] The hand portion 30 is attached to the other end face of the force sensor 20, and is provided on the tip side of the robot arm 10 via the force sensor 20, enabling it to hold the workpiece 90 or jig 75. The hand portion 30 is provided so as to protrude in a direction parallel to the central axis direction of the force sensor 20 (the extension direction of the tip of the robot arm 10), and has at least a pair of finger portions 31 that can move in a direction perpendicular to the central axis direction of the force sensor 20 to grip the jig 75. The gripping mechanism with the finger portion 31 is similar to that of a known gripper-type robot hand, and therefore a detailed explanation is omitted.

[0024] In the hand portion 30, the fingers 31 are positioned relative to the jig 75 so that the jig's center of gravity is located along the central axis of the force sensor 20, thereby gripping the jig 75. It is desirable to adjust the contact position of the finger portion 31 with the side surface of the jig 75 so that the vertical center position of the finger portion 31 coincides with the vertical center position of the side surface of the jig 75, so that the gripping by the finger portion 31 is stable around the center of gravity of the jig 75.

[0025] The control unit 40 is connected to each actuator (not shown) in the robot arm 10 and the hand unit 30, and controls the operation of the robot arm 10 and the hand unit 30. Furthermore, the control unit 40 is connected to the force sensor 20 and receives signals output from the force sensor 20 when it detects force or moment. The control unit 40 then determines the force or moment from the signals and uses them to control the robot arm 10 and the hand unit 30.

[0026] As control for the first half of the jig placement process, the control unit 40 operates the robot arm 10 to move the jig 75, bringing the bottom surface 75a of the jig 75 into contact with the first reference surface 72a of the workpiece fixing part 71. Furthermore, based on the detection result of the force sensor 20, the control unit 40 operates the robot arm 10 to adjust the position and orientation of the jig 75 until the entire bottom surface 75a of the jig 75 is in contact with the first reference surface 72a, while maintaining the contact state between a part of the bottom surface 75a of the jig 75 and the first reference surface 72a. Furthermore, as control for the latter half of the jig placement process, the control unit 40 operates the robot arm 10 to move the jig 75, causing a portion of the contact portion 75b of the jig 75 to come into contact with the contact surface 95 of the workpiece 90. In addition, based on the detection results of the force sensor 20, the control unit 40 operates the robot arm 10 to adjust the position and orientation of the jig 75, while maintaining the contact state between a portion of the contact portion 75b and the contact surface 95, until the contact portion 75b of the jig 75 makes line contact with the contact surface 95.

[0027] In these cases, the control unit 40 determines from the signal received from the force sensor 20 whether a part of the jig 75 has come into contact with a part of the first reference surface 72a or a part of the contacted surface 95. Specifically, the force sensor 20 detects the moment of force applied to the jig 75 due to the contact between the jig 75 and the first reference surface 72a or the contacted surface 95, and the control unit 40 recognizes the contact between the jig 75 and the first reference surface 72a or the contacted surface 95.

[0028] When the control unit 40 detects a moment with the force sensor 20, it operates the robot arm 10 to apply a torque to the jig 75 in the same direction as the moment, bringing the surface of the jig 75 closer to the first reference surface 72a or the surface to be contacted 95 while maintaining partial contact. Then, the control unit 40 issues a command to stop the operation of the robot arm 10 when the moment detected by the force sensor 20 becomes zero.

[0029] If the robot arm 10 moves due to inertia after a stop command and the force sensor 20 detects a moment in the opposite direction to the previous moment, the control unit 40 operates the robot arm 10 to apply a torque in the same direction as the detected moment to the jig 75.

[0030] The control unit 40 causes the robot arm 10 to repeatedly perform these steps, bringing the jig 75 closer to the first reference surface 72a or to the surface to be contacted 95 in line. When the jig 75 makes complete surface contact with the first reference surface 72a, or complete line contact with the contacted surface 95, the moment detected by the force sensor 20 becomes 0 and remains unchanged.

[0031] Therefore, in the first half of the jig placement process, if the moment detected by the force sensor 20 remains at zero, and a predetermined period has elapsed since the start of the operation related to contact with the first reference surface 72a, the control unit 40 determines that the jig 75 has achieved surface contact with the first reference surface 72a. The control unit 40 then shifts control of the robot arm 10 to the second half of the jig placement process. Furthermore, in the latter half of the jig placement process, if the moment detected by the force sensor 20 remains at zero and a predetermined period has elapsed since the start of the operation related to contact with the contact surface 95, the control unit 40 determines that the jig 75 has achieved line contact with the contact surface 95. The control unit 40 then stops the operation of the robot arm 10.

[0032] Prior to the jig placement process, the transfer device 1 grasps the jig 75, which has been placed in a predetermined initial position, with its hand unit 30 and, while holding it, moves its robot arm 10 to perform a jig loading process, moving it to the space near the pre-placed workpiece 90 on the workpiece fixing unit 71 of the machine tool 70.

[0033] Furthermore, the initial holding of the jig 75 by the hand unit 30 in the jig loading process is performed using the following procedure. First, the robot arm 10 is operated to adjust the position and orientation of the hand unit 30 so that the jig 75, which is initially placed in its position, is positioned between the pair of finger units 31 of the hand unit 30 (see Figure 3(a)).

[0034] Next, while maintaining the overall position of the hand portion 30, the pair of finger portions 31 of the hand portion 30 are moved toward each other, and the jig 75 is grasped with the finger portions 31 (see Figure 3(b)), completing the holding of the jig 75 by the hand portion 30.

[0035] This jig loading process involves the control unit 40 causing the robot arm 10 and hand unit 30 to perform an operation in accordance with a series of procedures previously taught to them. The control involved in this execution is based on a general robot control method that reproduces the taught movements, and a detailed explanation is omitted.

[0036] Next, the jig placement process in the jig placement method according to this embodiment will be described. As a prerequisite, the transfer device 1 has already performed the jig loading process. That is, the transfer device 1 holds the jig 75, which is placed in a predetermined initial position, with the hand unit 30, and moves the robot arm 10 to move the jig 75 to the space near the workpiece 90 and the first reference surface 72a on the workpiece fixing unit 71 of the machine tool 70.

[0037] Furthermore, the second reference surface 73a, which is the side surface of the reference jig 73 on the machine tool 70, is positioned relative to the hand portion 30 in the central axis direction of the force sensor 20. In this case, the contact surface 95 on the workpiece 90 opposite to the surface in contact with the second reference surface 73a is in a positional relationship with the jig 75.

[0038] In the jig placement process, the first step is to position the jig 75 on the first reference surface 72a, which is the table surface (upper surface of the magnetic chuck 72) of the workpiece fixing section 71. The transfer device 1 moves the jig 75, held by the hand section 30 at the tip of the robot arm 10, closer to the first reference surface 72a located below, so that a part of the bottom surface 75a of the jig 75 comes into contact with the first reference surface 72a (see Figure 4(a)).

[0039] The control unit 40 determines from the signal received from the force sensor 20 whether a part of the jig 75 has come into contact with a part of the first reference surface 72a. Specifically, the contact between the jig 75 and the first reference surface 72a causes a moment to be applied to the jig 75 about the x-axis, which is defined in space as an axis parallel to the first reference surface 72a. When this moment about the x-axis is detected by the force sensor 20, the control unit 40 recognizes the contact between the jig 75 and the first reference surface 72a.

[0040] When the control unit 40 detects contact between the jig 75 and the first reference surface 72a, it moves the robot arm 10 so that a torque in the same direction as the detected moment is applied to the jig 75 via the hand unit 30. This reduces the inclination of the bottom surface 75a of the jig 75 relative to the first reference surface 72a. At the same time, the operating state of the robot arm 10 is adjusted to push the jig 75 toward the first reference surface 72a with a predetermined force so that contact between a part of the jig 75 and the first reference surface 72a is maintained. This pushing force is set so as not to damage the jig 75 and the table surface (first reference surface 72a) through contact with each other. When torque and force are applied to the jig 75, it tilts relative to the first reference surface 72a, with the point of contact with the first reference surface 72a acting as a fulcrum.

[0041] As the robot arm 10 operates, a predetermined entire side of the bottom surface 75a of the jig 75, or the entire bottom surface 75a, comes into contact with the first reference surface 72a (see Figure 4(b)). When the moment applied to the jig 75 becomes zero and the force sensor 20 detects zero moment, the control unit 40 issues a command to stop the robot arm 10 from operating.

[0042] However, normally, the robot arm 10 cannot stop simultaneously with the stop command. From the time the control unit 40 issues a command to stop the robot arm 10's operation until the robot arm 10 actually stops, the robot arm 10 continues to move due to inertia. As the robot arm 10 continues to move until it stops, torque is applied to the jig 75 for a short period of time.

[0043] Therefore, the edge or face of the jig 75 tilts slightly in the same direction as before, from the state in which it was in contact with the first reference surface 72a, and tilts in a different direction relative to the first reference surface 72a than initially. The jig 75 then comes into contact with the first reference surface 72a at a different point than where it was initially in contact, and stops in a state where it is otherwise separated from the first reference surface 72a (see Figure 4(c)). As this contact between other parts of the jig 75 and the first reference surface 72a occurs, a moment is applied to the jig 75 around the x-axis in the opposite direction to the initial contact with the first reference surface 72a, and this moment is detected by the force sensor 20.

[0044] If the force sensor 20 detects a moment in the opposite direction, the control unit 40 moves the robot arm 10 in response to the detected moment, so that a torque in the same direction as the detected moment is applied to the jig 75. With the torque and force applied, the jig 75 then tilts relative to the first reference surface 72a, with the point of contact with the first reference surface 72a as the pivot point.

[0045] By repeating these steps, the position and orientation of the jig 75 are adjusted until the entire bottom surface 75a of the jig 75 remains in contact with the first reference surface 72a, while maintaining contact between a portion of the jig 75 and the first reference surface 72a. Specifically, if the force sensor 20 continues to detect a moment of 0 around the x-axis, and a predetermined period of time has elapsed since the start of operation related to contact between the transfer device 1 and the first reference surface 72a, the control unit 40 determines that the entire bottom surface 75a of the jig 75 is in contact with the first reference surface 72a. Then, while causing the robot arm 10 to maintain surface contact between the jig 75 and the first reference surface 72a, the control unit 40 completes the first half of the jig placement process with respect to the first reference surface 72a and proceeds to the second half of the jig placement process.

[0046] In the latter half of the jig placement process, the jig 75 is positioned on the contact surface 95 of the workpiece 90 that is opposite to the surface that contacts the second reference surface 73a. In this case as well, similar to the positioning on the first reference surface 72a, the transfer device 1 brings the jig 75, held by the hand portion 30 at the tip of the robot arm 10, closer to the surface to be contacted 95, causing a portion of the contact portion 75b of the jig 75 to come into contact with the surface to be contacted 95 (see Figure 5(a)).

[0047] In the jig 75, the contact portion 75b that is intended to contact the surface to be contacted 95 is a projection that protrudes laterally from the upper part of the bottom surface 75a, parallel to the bottom surface 75a. Therefore, even when the contact portion 75b and the surface to be contacted 95 come into contact, the parts of the jig 75 other than the contact portion 75b remain at a distance from the workpiece 90. When machining the workpiece 90, if the size of the workpiece 90 is smaller than that of the reference jig 73, a lower jig 77 is placed below the workpiece 90 to ensure that the amount of overhang of the top of the workpiece 90 from the reference jig 73 is appropriate (see Figures 4 and 8). The mounting surface (upper surface) of the lower jig 77 on which the workpiece 90 is placed is made larger than the workpiece 90 in order to securely support the workpiece 90, and therefore it will protrude outward from the workpiece 90. In contrast, the jig 75 has a shape with a protruding contact portion 75b, so even if the lower jig 77 is positioned below the workpiece 90, the jig 75 will not come into contact with the lower jig 77. In other words, in situations where it is desired that the jig 75 be in contact with the contact surface 95, the jig 75 will come into contact with the lower jig 77, and the situation in which the contact portion 75b cannot be properly brought into contact with the workpiece 90 can be reliably prevented.

[0048] The control unit 40 determines from the signal received from the force sensor 20 whether a part of the jig 75 has come into contact with a part of the surface to be contacted 95. Specifically, the contact between the jig 75 and the surface to be contacted 95 causes a moment around the z-axis, which is defined in space as an axis parallel to the surface to be contacted 95, to be applied to the jig 75. When this moment around the z-axis is detected by the force sensor 20, the control unit 40 recognizes that the jig 75 has come into contact with the surface to be contacted 95.

[0049] When the control unit 40 recognizes contact between the jig 75 and the surface to be contacted 95, it moves the robot arm 10 so that a torque in the same direction as the detected moment is applied to the jig 75 via the hand unit 30. This reduces the inclination of the contact portion 75b of the jig 75 relative to the surface to be contacted 95. At the same time, the operating state of the robot arm 10 is adjusted to push the jig 75 toward the surface to be contacted 95 with a predetermined force so that contact between a part of the jig 75 and the surface to be contacted 95 is maintained. This pushing force is also set to an extent that does not damage the jig 75 and the workpiece 90 through contact with each other. When torque and force are applied to the jig 75, it tilts relative to the contact surface 95, with the point of contact with the contact surface 95 acting as a pivot point.

[0050] When the robot arm 10 is operated, the tip of the contact portion 75b of the jig 75 makes linear contact with the contact surface 95 through the linear contact portion (see Figure 5(b)). When the moment applied to the jig 75 becomes 0 and the moment detection by the force sensor 20 becomes 0, the control unit 40 issues a command to stop the operation of the robot arm 10.

[0051] In this case as well, the robot arm 10 may continue to move due to inertia from the time the control unit 40 issues a command to stop the robot arm 10 until the robot arm 10 actually stops moving. During this short period of time when the robot arm 10 is moving, torque continues to be applied to the jig 75.

[0052] Consequently, the contact portion 75b of the jig 75 tilts slightly in the same direction as before, from a state where it was in line contact with the surface to be contacted 95, to a different direction relative to the surface to be contacted 95 than initially. The jig 75 then comes into contact with the surface to be contacted 95 at a different point than where it was initially in contact, and stops in a state where it is separated from the surface to be contacted 95 otherwise (see Figure 5(c)). As a result of this contact between the contact portion 75b of the jig 75 and the surface to be contacted 95, a moment about the z-axis is applied to the jig 75 in the opposite direction to the initial contact with the surface to be contacted 95, and this moment is detected by the force sensor 20.

[0053] If the force sensor 20 detects a moment in the opposite direction, the control unit 40 moves the robot arm 10 in response to the detected moment, so that a torque in the same direction as the detected moment is applied to the jig 75. With the torque and force applied, the jig 75 then tilts relative to the contact surface 95, with the point of contact with the contact surface 95 as the pivot point.

[0054] By repeating these steps, the position and orientation of the jig 75 are adjusted until the tip of the contact portion 75b of the jig 75 remains in line contact with the surface to be contacted 95, while maintaining contact between a part of the jig 75 and the surface to be contacted 95. Specifically, when the force sensor 20 continues to detect a moment of 0 around the z-axis, and a predetermined period of time has elapsed since the start of the operation related to contact with the surface to be contacted 95, the control unit 40 determines that the contact portion 75b of the jig 75 is in line contact with the surface to be contacted 95. The control unit 40 then stops the operation of the robot arm 10 and ends the jig placement process.

[0055] After the jig placement process, when the jig 75 is in contact with the workpiece 90 and supporting the workpiece 90, the contact portion 75b (contact surface 75c) of the jig 75 is in line contact with the contact surface 95 of the workpiece 90. If the tip of the contact portion of the jig is flat and surface contact is possible between the contact portion and the contact surface 95 of the workpiece 90, problems may arise if the flat surface on the contact portion side of the jig is not precisely perpendicular to the bottom surface. Specifically, in the contact state between the jig and the contact surface 95, the workpiece 90 tends to conform to the flat surface on the contact portion side due to surface contact, and in that case, the workpiece 90 will tilt according to the inclination of the flat surface on the contact portion side. If the workpiece 90 is fixed in this state, accurate machining of the workpiece 90 cannot be expected. In this embodiment, the jig 75 has a curved contact surface 75c at the tip of the contact portion 75b, so that even when it is in maximum contact with the contact surface 95 of the workpiece 90, it remains in line contact. Therefore, even when the jig 75 and the contact surface 95 come into contact, the state in which the workpiece 90 is aligned with the second reference surface 73a does not change, and the workpiece 90 is maintained in an appropriate position, allowing for accurate machining of the workpiece 90.

[0056] Next, we will explain each process in this jig placement process using the flowcharts shown in Figures 6 and 7. In the first half of the jig placement process, the control unit 40 first starts the operation of the robot arm 10, bringing the jig 75 held by the hand unit 30 closer to the first reference surface 72a of the workpiece fixing unit 71 (step S001).

[0057] When a part of the jig 75 comes into contact with the first reference surface 72a, the force moment applied to the jig 75 is detected by the force sensor 20, and the control unit 40 monitors the detection status of the force sensor 20. The control unit 40 determines whether a new moment has been detected by the force sensor 20, that is, whether a part of the jig 75 has come into contact with the first reference surface 72a (step S002). If the force sensor 20 detects a force moment and the control unit 40 determines that a part of the jig 75 has come into contact with the first reference surface 72a, the control unit 40 moves the robot arm 10 and applies a torque to the jig 75 in the same direction as the detected moment (step S003). On the other hand, if the force sensor 20 does not detect a force moment and the control unit 40 determines that a part of the jig 75 is not in contact with the first reference surface 72a, the process returns to step S002 and is repeated.

[0058] When torque is applied to the jig 75, the jig 75 tilts relative to the first reference surface 72a, with the point of contact with the first reference surface 72a as the pivot point, and the tilt of the jig 75 with respect to the first reference surface 72a decreases. When the entire bottom surface 75a of the jig 75, which corresponds to the first reference surface 72a, comes into contact with the first reference surface 72a, the moment detected by the force sensor 20 becomes 0. Based on this, the control unit 40 continuously monitors the detection status of the force sensor 20 and determines whether the moment detected by the force sensor 20 has reached 0, that is, whether the jig 75 has made surface contact with the first reference surface 72a (step S004).

[0059] In step S004, if the moment detected by the force sensor 20 becomes 0 and the control unit 40 determines that the jig 75 has made surface contact with the first reference surface 72a, the control unit 40 commands the robot arm 10 to stop operation. This command stops the operation of the robot arm 10 and the accompanying movement of the jig 75 (step S005).

[0060] On the other hand, if in step S004 the moment detected by the force sensor 20 has not reached zero and the control unit 40 determines that the bottom surface 75a of the jig 75 is not yet in surface contact with the first reference surface 72a, the process returns to step S003 and onward is repeated.

[0061] In step S005, even if the control unit 40 commands the robot arm 10 to stop, the robot arm 10 will normally try to continue moving due to inertia, making it difficult to stop it simultaneously with the command. If the robot arm 10 continues to move between the time the control unit 40 issues the command to stop operation and the time the robot arm 10 actually stops, the torque applied to the jig 75 will also continue.

[0062] As torque is continuously applied to the jig 75, the jig 75 tilts further from the state in which its bottom surface 75a is in surface contact with the first reference surface 72a before stopping. In this case, at the point of stopping, the jig 75 is tilted in a different direction from the first reference surface 72a than it was initially, and contacts the first reference surface 72a with parts other than the part that was initially in contact with the first reference surface 72a. Otherwise, it is once again separated from the first reference surface 72a. In this stopped state, contact with the first reference surface 72a occurs only at other parts of the jig 75, and as a result, the force moment applied to the jig 75 is detected by the force sensor 20, similar to the initial contact between the jig 75 and the first reference surface 72a. However, the direction of the moment detected in this state is opposite to the direction of the moment detected during the initial contact between the jig 75 and the first reference surface 72a.

[0063] On the other hand, if, for example, the moment detected by the force sensor 20 becomes zero immediately after torque is applied to the jig 75, the inertial force that causes the robot arm 10 to continue moving becomes extremely small. When the inertial force of the robot arm 10 is small in this way, the robot arm 10 stops almost immediately after the control unit 40 commands it to stop, and the jig 75 can maintain line contact with the contact surface 95.

[0064] Based on the behavior of the robot arm 10 and the jig 75 after such a stop command, the control unit 40 monitors the detection status of the force sensor 20 even after the stop command and determines whether the moment detected by the force sensor 20 remains at 0 (step S006). In other words, the control unit 40 determines whether the bottom surface 75a of the jig 75 remains in surface contact with the first reference surface 72a, or whether it tilts further without remaining in contact.

[0065] In step S006, if the force sensor 20 determines that the detected moment is not zero and that a predetermined moment has been detected, the control unit 40 returns to step S003 and repeats the subsequent processing. That is, in response to the detection of a moment, the control unit 40 moves the robot arm 10 so that a torque in the same direction as the moment is applied to the jig 75, causing the jig 75 to make surface contact with the first reference surface 72a. As the processing from step S003 onward is repeated in this way, the degree to which the robot arm 10 and the jig 75 continue to move after the jig 75 makes surface contact with the first reference surface 72a and the robot arm 10 is commanded to stop moving gradually decreases.

[0066] In step S006, if the moment detected by the force sensor 20 remains at 0 and the control unit 40 determines that the jig 75 is still in surface contact with the first reference surface 72a, the control unit 40 further determines the passage of time. Specifically, the control unit 40 determines whether a predetermined time has elapsed since the start of operation of the robot arm 10 related to the jig 75's contact with the first reference surface 72a in the jig placement process (step S007).

[0067] In step S007, if the control unit 40 determines that a predetermined time (for example, several seconds) has elapsed since the robot arm 10 started operating, the control unit 40 considers that the bottom surface 75a of the jig 75 has been properly positioned with surface contact with the first reference surface 72a, and terminates the processing of the first half of the jig placement process. Then, it proceeds to the processing of the second half of the jig placement process. On the other hand, if in step S007 the control unit 40 determines that a predetermined time has not elapsed since the start of operation of the robot arm 10, the process returns to step S006 and the subsequent processing is repeated.

[0068] In the latter half of the jig placement process, the control unit 40 restarts the operation of the robot arm 10, and while maintaining surface contact between the jig 75 held by the hand unit 30 and the first reference surface 72a, it moves the jig 75 closer to the contact surface 95 of the workpiece 90 (step S008).

[0069] When a part of the jig 75 comes into contact with the surface to be contacted 95, the force moment applied to the jig 75 is detected by the force sensor 20, and the control unit 40 monitors the detection status of the force sensor 20. The control unit 40 determines whether a new moment has been detected by the force sensor 20, that is, whether a part of the jig 75 has come into contact with the surface to be contacted 95 (step S009). If the force sensor 20 detects a force moment and the control unit 40 determines that a part of the jig 75 has come into contact with the surface to be contacted 95, the control unit 40 moves the robot arm 10 and applies a torque to the jig 75 in the same direction as the detected moment (step S010). On the other hand, if the force sensor 20 does not detect a force moment and the control unit 40 determines that a part of the jig 75 is not in contact with the contact surface 95, the process returns to step S009 and is repeated.

[0070] When torque is applied to the jig 75, the jig 75 tilts relative to the reference plane with the contact point with the surface to be contacted 95 as the pivot point, and the tilt of the jig 75 relative to the surface to be contacted 95 decreases. When the entire tip of the contact portion 75b of the jig 75 corresponding to the surface to be contacted 95 comes into contact with the surface to be contacted 95, the moment detected by the force sensor 20 becomes 0. Based on this, the control unit 40 continuously monitors the detection status of the force sensor 20 and determines whether the moment detected by the force sensor 20 has reached 0, that is, whether the jig 75 has made line contact with the surface to be contacted 95 (step S011).

[0071] In step S011, if the moment detected by the force sensor 20 becomes 0 and the control unit 40 determines that the jig 75 has made line contact with the contact surface 95, the control unit 40 commands the robot arm 10 to stop operation. This command stops the operation of the robot arm 10 and the accompanying movement of the jig 75 (step S012).

[0072] On the other hand, if in step S011 the moment detected by the force sensor 20 has not reached zero and the control unit 40 determines that the jig 75 has not yet made line contact with the contact surface 95, the process returns to step S010 and is repeated.

[0073] In step S012, even if the control unit 40 commands the robot arm 10 to stop, the robot arm 10 usually tries to continue moving due to inertia, making it difficult to stop it simultaneously with the command. If the robot arm 10 continues to move between the time the control unit 40 issues the command to stop operation and the time the robot arm 10 actually stops, the condition in which torque is applied to the jig 75 will also continue.

[0074] As torque is continuously applied to the jig 75, the jig 75 tilts further from the state where its contact portion 75b is in line contact with the surface to be contacted 95 before stopping. In this case, at the point of stopping, the jig 75 is tilted in a different direction relative to the surface to be contacted 95 than it was initially, and contacts the surface to be contacted 95 with a portion other than the portion that was initially in contact with the surface to be contacted 95. Otherwise, it is separated from the surface to be contacted 95 again. In this stopped state, since contact with the surface to be contacted 95 occurs only at other parts of the jig 75, the force moment applied to the jig 75 is detected by the force sensor 20, just as it was during the initial contact between the jig 75 and the surface to be contacted 95. However, the direction of the moment detected in this state is opposite to the direction of the moment detected during the initial contact between the jig 75 and the surface to be contacted 95.

[0075] On the other hand, if, for example, the moment detected by the force sensor 20 becomes zero immediately after torque is applied to the jig 75, the inertial force that causes the robot arm 10 to continue moving becomes extremely small. When the inertial force of the robot arm 10 is small in this way, the robot arm 10 stops almost immediately after the control unit 40 commands it to stop, and the jig 75 can maintain line contact with the contact surface 95.

[0076] Based on the behavior of the robot arm 10 and the jig 75 after such a stop command, the control unit 40 monitors the detection status of the force sensor 20 even after the stop command and determines whether the moment detected by the force sensor 20 remains at 0 (step S013). In other words, the control unit 40 determines whether the contact portion 75b of the jig 75 remains in line contact with the contacted surface 95, or whether it tilts further without remaining in line contact.

[0077] In step S013, if the force sensor 20 determines that the detected moment is not zero and that a predetermined moment has been detected, the control unit 40 returns to step S010 and repeats the subsequent processing. That is, in response to the detection of a moment, the control unit 40 moves the robot arm 10 so that a torque in the same direction as the moment is applied to the jig 75, causing the jig 75 to make line contact with the contact surface 95. As the processing from step S010 onward is repeated in this way, the degree to which the robot arm 10 and the jig 75 continue to move after the jig 75 makes line contact with the contact surface 95 and the robot arm 10 is commanded to stop moving gradually decreases.

[0078] In step S013, if the moment detected by the force sensor 20 remains at 0 and the control unit 40 determines that the jig 75 is still in line contact with the contact surface 95, the control unit 40 further determines the passage of time. Specifically, the control unit 40 determines whether a predetermined time has elapsed since the start of the operation of the robot arm 10 related to the contact of the jig 75 with the contact surface 95 in the latter half of the jig placement process (step S014).

[0079] In step S014, if the control unit 40 determines that a predetermined time (for example, several seconds) has elapsed since the robot arm 10 started operating, the control unit 40 considers that the jig 75 has been brought into contact with the contact surface 95 and positioned appropriately, and terminates the series of processes. On the other hand, if in step S014 the control unit 40 determines that a predetermined time has not elapsed since the start of operation of the robot arm 10, the process returns to step S013 and the subsequent processing is repeated.

[0080] In the jig placement process, the robot arm 10 is operated to bring the jig 75 closer to the first reference surface 72a or the contact surface 95, or to maintain contact between the jig 75 and the first reference surface 72a or the contact surface 95. The force applied when moving the jig 75 is set to be such that pressing the jig 75 against the first reference surface 72a or the contact surface 95 does not cause any damage to the jig 75 or the first reference surface 72a or the contact surface 95, and the speed at which the jig 75 moves is sufficient.

[0081] The force applied when moving the jig 75 to bring it closer to the first reference surface 72a or the surface to be contacted 95, or when moving the jig 75 to maintain contact with the first reference surface 72a or the surface to be contacted 95, is kept approximately constant, but is not limited to this. For example, control may be applied to reduce the force as the first reference surface 72a or the surface to be contacted 95 approaches the corresponding surface of the jig 75. Similarly, the magnitude of the torque used to tilt the jig 75 may also be controlled to decrease as the first reference surface 72a or the surface to be contacted 95 approaches the corresponding surface of the jig 75.

[0082] Furthermore, the process of releasing the jig after the placement process will be explained. Once the jig placement process, in which the jig 75 is brought into line contact with the contact surface 95 of the workpiece 90, is completed, the jig release process is performed, in which the hand unit 30 releases its grip on the jig 75. This jig release process is carried out in the following procedure.

[0083] First, with the hand portion 30 applying a pressing force to the jig 75 against the contact surface 95 of the workpiece 90, the magnetic chuck 72 of the workpiece fixing portion 71 is activated, fixing the jig 75 to the workpiece fixing portion 71 by attraction of the magnetic chuck 72. Consequently, the workpiece 90, sandwiched between the second reference surface 73a of the workpiece fixing portion 71 and the jig 75, also becomes fixed. After fixing the jig 75, the pair of fingers 31 of the hand portion 30 are moved away from each other, releasing the gripping state of the jig 75 by the fingers 31 (see Figure 9).

[0084] Next, the robot arm 10 is activated to move the hand unit 30, and the entire hand unit 30 is moved away from the jig 75. Needless to say, the hand unit 30 is moved in such a way that none of its parts come into contact with the jig 75.

[0085] The jig release process is completed when the hand unit 30, which has been separated from the jig 75, is moved to a predetermined position, for example, the initial position when the jig loading process is performed, and left waiting in preparation for removing the jig after workpiece processing. However, the movement of the hand unit 30 separated from the jig 75 is not limited to this. For example, if, after machining the workpiece, it is necessary to change the position or orientation of the workpiece and further machine other surfaces of the workpiece, the jig will need to be attached and detached multiple times. In such cases, the hand unit can be moved to a standby position to accommodate these operations. After the workpiece processing is complete, the transfer device 1 holds the jig 75, which has finished its job, in the reverse order of its placement, and removes it from the workpiece fixing section 71. The jig 75, along with the hand section 30, is then moved to the initial position of the jig loading process. After this, the transfer device 1 releases the hand section 30 from holding the jig 75 and repositions the jig 75 to its initial position, while moving the hand section 30 to a predetermined standby position in preparation for holding a new jig.

[0086] As described above, the jig placement method according to this embodiment involves using the transfer device 1, which holds the jig 75, to direct the jig 75 toward the contact surface 95 of the workpiece 90, which is positioned on the workpiece fixing section 71, thereby creating a line contact state between the contact portion 75b of the jig 75 and the contact surface 95. This allows the jig 75 to be appropriately positioned relative to the workpiece 90, correctly fixing the workpiece 90 and enabling accurate machining of the workpiece 90. Furthermore, since the automation of jig placement can be easily achieved with the transfer device 1, structural changes to the machine tool are unnecessary, the complexity and size of the machine tool itself can be avoided, and the costs associated with introducing and using the machine tool can be reduced.

[0087] In this embodiment, the jig arrangement method is shown as an example of application to a machine tool 70 which is a surface grinding machine, but it is not limited to this and may be applied to other machine tools. For example, the machine tool may be a machining center or a milling machine, and the present invention may be applied to the arrangement of jigs for fixing workpieces to these machines.

[0088] Furthermore, in the jig 75 arranged by the jig arrangement method according to this embodiment, the protruding connecting portion 75b of the jig 75, which protrudes in a direction parallel to the bottom surface 75a, has a contact surface 75c at its tip, which is a semi-cylindrical curved surface. As a result, when the transfer device 1 brings the contact portion 75b of the jig 75 into contact with the contact surface 95 of the workpiece 90, the tip portion (contact surface 75c) of the contact portion 75b makes line contact with the contact surface 95 of the workpiece 90. However, this is not the only option, and the tip of the connecting part of the jig and the contact surface of the workpiece may be in a contact state other than line contact, such as point contact. For example, the tip of the contact part of the jig may be made into a hemispherical curved shape so that the tip of the contact part makes point contact with the contact surface of the workpiece. In this case as well, when the jig and the contact surface come into contact, the state in which the workpiece is aligned with the second reference surface of the workpiece fixing part does not change, and the workpiece can be maintained in an appropriate position, ensuring that accurate machining can be performed on the workpiece.

[0089] Furthermore, in the jig placement method according to this embodiment, in the first half of the jig placement process, an example is shown in which the bottom surface 75a of the jig 75 can be brought into surface contact with the first reference surface 72a by adjusting only the orientation of the jig 75 around the x-axis while bringing the entire jig 75 closer to the first reference surface 72a. That is, an example is given in which the bottom surface 75a of the jig 75 that is to be positioned relative to the first reference surface 72a of the workpiece fixing part 71 is inclined only around the x-axis and z-axis defined in space, and the placement process is set up to correspond to this.

[0090] However, the jig placement process is not limited to such specific cases. For example, as shown in Figure 10, it can also handle cases where the bottom surface 75a of the jig 75, which is to be positioned by contacting the first reference surface 72a, is inclined not only around the x and z axes defined in space, but also around the y axis.

[0091] In this case, during the first half of the jig placement process, the entire jig 75 is brought closer to the first reference surface 72a of the workpiece fixing part 71, and the orientation adjustment of the jig 75 around the x-axis and around the y-axis is performed simultaneously based on the moment detection around each axis by the force sensor 20. When the entire bottom surface 75a of the jig 75 is in contact with the first reference surface 72a and the moment detection around the x-axis and y-axis by the force sensor 20 becomes 0 for a predetermined time, the first half of the jig placement process can be considered complete, as in this embodiment.

[0092] Furthermore, in the jig placement method according to this embodiment, the first reference surface 72a (table surface) of the workpiece fixing part 71 and the contact surface 95, which is the side surface of the workpiece 90, are used as target surfaces for placing the jig 75. However, the present invention may be applied not only to cases where there are two target surfaces for placement, but also when, in addition to two target surfaces that are perpendicular to each of these two target surfaces, another target surface that is perpendicular to each of these two target surfaces is used when placing the jig, that is, when three target surfaces are used for placing the jig.

[0093] Furthermore, in the jig placement method according to this embodiment, the condition for determining the end of the jig placement process is that the control unit 40 continuously determines that the moment detected by the force sensor 20 is 0, with respect to the movement state of the jig 75 during the jig placement process. However, if there is foreign matter such as dust between the jig and the reference surface or the surface to be contacted, even if the jig is moved along the reference surface or the surface to be contacted, the jig may not be able to make close contact with the reference surface or the surface to be contacted, causing the force sensor to continue detecting a moment and potentially preventing the placement process from being completed. In such cases where the force sensor continues to detect a moment for an abnormally long period, the control unit may determine that there is foreign matter between the jig and the reference surface or the surface to be contacted, stop the operation of the robot arm, and perform control to give a predetermined notification to the operator. [Explanation of Symbols]

[0094] 1 Transfer device 10 Robot Arms 20 Force Sensors 30 Hand section 31 Finger section 40 Control Unit 70 Machine tools 71 Workpiece fixing part 71a Table 72 Magnetic Chuck 72a, 73a Reference plane 73, 74 Standard fixtures 75 Jig 75a Bottom 75b Contact area 75c contact surface 77 Lower jig 90 Work 95 Contacted surface

Claims

1. The process includes at least a jig placement step in which a jig for fixing a workpiece is held and moved by a predetermined transfer device to the workpiece fixing section of a machine tool that fixes the workpiece to be processed, and the jig is placed on the workpiece fixing section. The jig is a three-dimensional object having a bottom surface and a protruding contact portion that extends in a direction parallel to the bottom surface. The workpiece fixing portion has a first reference surface and a second reference surface perpendicular to the first reference surface, and prior to the jig placement process, the workpiece is positioned in close contact with the second reference surface. In the jig placement step, the transfer device adjusts the position and orientation of the jig so that the bottom surface of the jig is in surface contact with the first reference surface of the workpiece fixing part, and at least the tip portion of the contact part is in contact with the contact surface of the workpiece on the workpiece fixing part that is opposite to the contact surface with the second reference surface. A distinctive jig arrangement method.

2. In the jig arrangement method described in claim 1, In the jig placement step, the transfer device adjusts the position and orientation of the jig while the bottom surface of the jig is in surface contact with the first reference surface of the workpiece fixing part, so that the tip portion of the contact part makes at least line contact with the contact surface of the workpiece on the workpiece fixing part that is opposite to the contact surface with the second reference surface. A distinctive jig arrangement method.

3. In the jig arrangement method described in claim 1, The transfer device has a force sensor capable of detecting the force and moment generated in the jig it holds, In the jig placement step, the transfer device brings at least a portion of the contact portion of the jig into contact with the surface to be contacted, and then, based on the detection result of the force sensor, adjusts the position and orientation of the jig while maintaining the contact state between the portion of the contact portion and the surface to be contacted, until the tip portion of the contact portion makes at least line contact with the surface to be contacted. A distinctive jig arrangement method.

4. In the jig arrangement method according to claim 2 or 3, In the jig placement process, The transfer device brings at least a portion of the bottom surface of the jig into contact with the first reference surface, and then, based on the detection result of the force sensor, adjusts the position and orientation of the jig until the entire bottom surface comes into contact with the first reference surface, while maintaining the contact between the portion of the bottom surface and the first reference surface. While maintaining the surface contact state between the first reference surface and the bottom surface, the position and orientation of the jig related to the contact between the surface to be contacted and the contact portion are to be adjusted. A distinctive jig arrangement method.

5. In the jig arrangement method according to claim 2 or 3, The jig placement step is, When a part of the contact portion of the jig comes into contact with the contact surface of the workpiece, the force sensor detects the moment of force generated in the jig, and the transfer device generates a torque in the same direction as the moment to tilt the jig, and at the same time causes the transfer device to continue moving the jig closer to the contact surface in order to maintain contact of the part of the contact portion with the contact surface, and when the moment of force detected by the force sensor becomes zero, the transfer device stops moving the jig, a series of steps, The movement of the transfer device and the jig from the moment the force moment becomes zero until it actually stops causes only a different part of the jig to contact the contacted surface, and each time the force sensor detects a newly generated force moment in the jig with a different direction than before, the process is repeated. The process is considered complete when a predetermined time has elapsed since the start of the operation in the transfer device to bring the jig into contact with the surface to be contacted. A distinctive jig arrangement method.

6. In the jig arrangement method described in claim 1, The machine tool is a grinding machine having a table capable of fixing a workpiece to be ground as at least part of the workpiece fixing portion, The first reference surface is the top surface of the table, The second reference surface is the side surface of another jig fixed to the table surface that is perpendicular to the table surface. A distinctive jig arrangement method.

7. The machine tool's workpiece fixing section, which secures the workpiece to be processed, is equipped with at least a transfer means that can move and position a workpiece fixing jig. The jig is a three-dimensional object having a bottom surface and a protruding contact portion that extends in a direction parallel to the bottom surface. The workpiece fixing portion has a first reference surface and a second reference surface perpendicular to the first reference surface, and the workpiece is pre-positioned to be in close contact with the second reference surface. The transfer means holds and moves the jig, bringing the bottom surface of the jig into surface contact with the first reference surface of the workpiece fixing portion, and bringing at least the tip portion of the contact portion into contact with the contacted surface of the workpiece opposite to the contact surface with the second reference surface, thereby enabling the jig to be positioned on the workpiece fixing portion. A transfer device that features a distinctive design.

8. In the transfer device according to claim 7, The transfer means holds and moves the jig, bringing the bottom surface of the jig into surface contact with the first reference surface of the workpiece fixing portion, and bringing at least the tip portion of the contact portion into line contact with the contacted surface of the workpiece opposite to the contact surface with the second reference surface, thereby enabling the jig to be positioned on the workpiece fixing portion. A transfer device that features a distinctive design.

9. In the transfer device according to claim 7, The jig is equipped with a force sensor capable of detecting the force or moment generated therein. While maintaining contact between the contact surface of the workpiece and at least a portion of the contact portion of the jig, the position and orientation of the jig are adjusted based on the detection result of the force sensor so that the tip portion of the contact portion makes at least line contact with the contact surface. A transfer device that features a distinctive design.

10. In the transfer device according to claim 8 or 9, The transfer means comprises a robot arm with multiple degrees of freedom and a hand portion provided at the tip of the robot arm capable of holding the jig. The force sensor is interposed between the tip of the robot arm and the hand portion. A transfer device that features a distinctive design.

11. In a jig used to fix a workpiece, which is detachably positioned on the workpiece fixing part of a machine tool that fixes the workpiece to be processed, It is formed as a three-dimensional object having a base and a protruding contact portion that extends in a direction parallel to the base, The tip portion of the contact area is shaped to be able to make line contact with a virtual plane perpendicular to the bottom surface using a line parallel to the bottom surface. A distinctive jig.

Images