Parts gripping device

Abstract

To prevent the grip load from becoming unstable due to the occurrence of prying in the gripper drive means, to easily control torque regardless of the degree of opening and closing or the opening and closing speed of the chuck part, to prevent free rotation and vibration caused by lost motion occurring in the gripper drive means, and to extend the life of the Z-axis movement means and rotation means and prevent a decrease in operating accuracy. [Solution] The torque control means of the gripper drive means 15 temporarily controls the torque of the opening / closing motor to 0 at the same time as the left chuck portion 11 or the right chuck portion 12 collides with the component 8 (see Figure 4(D)). Then, the servo of the opening / closing motor is momentarily turned off, the prying is resolved, and the perpendicularity between the left moving block 23 etc. and the ball screw 22 and the perpendicularity between the left chuck portion 11 etc. and the linear guide 25 return to normal. After that, the servo of the opening / closing motor is turned on again, so the component clamping force by the left and right chuck portions 11, 12 is maintained stably.

Description

[Technical Field]

[0001] The present invention relates to a part gripping device that includes a gripper for gripping a part, a gripper drive means for opening and closing the gripper, and a torque control means for controlling the torque generated by a motor that constitutes the gripper drive means. [Background technology]

[0002] There are known odd-shaped component mounting machines that grip various types of components and transport them to the desired position on the surface of a circuit board or the like for mounting. In such odd-shaped component mounting machines, the component gripping device grips the component and transports it to the desired position, so it is necessary to maintain a stable component clamping force (grip load) applied by the chuck of the gripper. However, when the chuck part collides with the part, a load is applied to the gripper driving means, which can cause prying and make the grip load unstable. In order to prevent such a phenomenon from occurring, Patent Document 1 (JP Patent Publication No. 11-114865) discloses that in a linear motor chuck (1) (corresponding to a "part gripping device") having a linear motor (3) (corresponding to a "motor"), fingers (5,5) (corresponding to a "chuck section") that grip a workpiece (corresponding to a "part"), and a guide mechanism (6) (corresponding to a "motor that opens and closes the gripper) that guides the opening and closing of the fingers (5,5), by controlling the amount of current flowing through the coil (12) that drives the linear motor (3) with a controller (15), the gripping force of the fingers (5,5) on the workpiece can be freely adjusted, and no prying occurs when the fingers (5,5) are opened and closed, resulting in a smooth opening and closing operation (see, in particular, paragraphs 0020 to 0021 and Figure 1).

[0003] Furthermore, Patent Document 2 (JP 2008-294305 A) discloses that in a component mounting device, a large load is placed on the connection between the X moving axis (120) and the Y moving axes (110a, 110b), causing it to become distorted and making it impossible to correct squareness, and to solve this problem, the patent discloses that the Y moving axis (110b) is confirmed to be servo-free, and then a magnetic pole detection operation for the Y moving axis (110a) is performed, and then the Y moving axes (110a, 110b) are servo-locked (see in particular paragraphs 0007, 0017, 0026-0029 and Figures 1 and 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-114865 [Patent Document 2] JP 2008-294305 A (Patent No. 4960148 A) Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the linear motor type chuck (1) described in Patent Document 1, the amount of current flowing through the coil (12) that drives the linear motor (3) is controlled to adjust the gripping force of the workpiece by the fingers (5, 5) in accordance with the strength of the workpiece, and the configuration for preventing the fingers (5, 5) from prying when opening and closing and for ensuring smooth opening and closing operations is such that the lever (24) and the fingers (5, 5) are engaged with the engaging element (24b) of the lever having a spherical portion and the engaging hole (5a) on the top surface of the finger, and therefore a special configuration had to be adopted for the opening and closing mechanism of the fingers (5, 5). Furthermore, although the component mounting device described in Patent Document 2 is similar in that it solves the problem of prying, it targets the connection part between the X moving axis (120) and the Y moving axes (110a, 110b), and not the gripper driving means. The present invention has a first objective to prevent the grip load from becoming unstable due to prying of the gripper drive means when the chuck collides with a part, without employing an opening / closing mechanism with a special configuration, a second objective to easily control torque regardless of the degree of opening and closing or the opening / closing speed of the chuck, a third objective to prevent free rotation and vibration caused by lost motion occurring in the gripper drive means, and a fourth objective to improve the lifespan, ability to handle high loads, and operational accuracy of the Z-axis movement means that moves the gripper and gripper drive means, etc. up and down, and the rotation means that rotates the gripper drive means, etc. around the central axis. [Means for solving the problem]

[0006] The invention according to claim 1 to solve the above problem is: A part gripping device comprising: a gripper for gripping a part; a gripper drive means for opening and closing the gripper; and a Z-axis direction movement means for moving the gripper and the gripper drive means up and down, The gripper driving means a motor that drives the gripper in a closing direction and an opening direction; and a torque control means for driving the gripper in a closing or opening direction, and temporarily reducing the torque generated by the motor immediately after the chuck portion of the gripper collides with the part, and then controlling the torque to a predetermined value.

[0007] The invention according to claim 2 for solving the above problem is the part gripping device according to claim 1, The torque control means temporarily reduces the torque generated by the motor to zero and then controls the torque to a predetermined value, regardless of the degree of opening or closing and the opening / closing speed of the chuck portion.

[0008] The invention according to claim 3 for solving the above problem is the part gripping device according to claim 1 or 2, The gripper driving means includes a conversion mechanism that converts the rotational force of the motor into a force that causes the gripper to open and close in a straight line; The present invention is characterized in that it further includes an air spring that applies a constant biasing force in the opposite direction to the conversion mechanism, whether the conversion mechanism is converting the rotational force of the motor into a force to open the gripper or a force to close the gripper.

[0009] The invention according to claim 4 for solving the above problem is the part gripping device according to claim 1 or 2, the part holding device further includes a rotation means for rotating the gripper, the gripper driving means, and the Z-axis direction moving means around a central axis, The Z-axis direction moving means is disposed above the center of the gripper, The rotating means is characterized in that it is disposed around the Z-axis direction moving means. [Effects of the Invention]

[0010] In the part holding device of the invention according to claim 1, the gripper drive means comprises a motor that drives the gripper in a closing and opening direction, and a torque control means that drives the gripper in a closing or opening direction and temporarily reduces the torque generated by the motor immediately after the chuck portion of the gripper collides with the part, and then controls it to a predetermined torque. Therefore, without employing an opening / closing mechanism with a special configuration, it is possible to prevent the grip load from becoming unstable even if the gripper drive means becomes twisted when the chuck portion collides with the part.

[0011] In the part holding device of the invention according to claim 2, in addition to the effect of the invention according to claim 1, the torque control means temporarily sets the torque generated by the motor to zero and then controls it to a predetermined torque, regardless of the degree of opening or closing or the opening / closing speed of the chuck portion, so that torque can be easily controlled regardless of the degree of opening or closing or the opening / closing speed of the chuck portion.

[0012] In the part gripping device of the invention of claim 3, in addition to the effects of the invention of claim 1 or 2, the gripper drive means further includes a conversion mechanism that converts the rotational force of the motor into a force that opens and closes the gripper in a straight line, and an air spring that applies a constant biasing force in the opposite direction to the conversion mechanism whether the conversion mechanism is converting the rotational force of the motor into a force that opens the gripper or a force that closes the gripper. This makes it possible to prevent free rotation and vibration caused by lost motion that occurs in the gripper drive means.

[0013] In addition to the effects of the invention of claim 1 or 2, the part holding device of the invention of claim 4 is equipped with a Z-axis direction movement means that moves the gripper and gripper drive means up and down, and a rotation means that rotates the gripper, gripper drive means, and Z-axis direction movement means around a central axis, and the Z-axis direction movement means is arranged above the center of the gripper, and the rotation means is arranged around the Z-axis direction movement means.As a result, no unbalanced load is applied to the Z-axis direction movement means or the rotation means, and no large torque is generated between the two, which extends the life of the Z-axis direction movement means and the rotation means, makes it possible to handle heavy loads, and prevents a decrease in operating accuracy. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing the overall configuration of a component mounting apparatus to which a component gripping device according to a first embodiment is applied; [Figure 2] FIG. 1 is a diagram showing the configuration of a part gripping device according to a first embodiment. [Figure 3] 10A and 10B are diagrams illustrating the operation of a torque control means in a conventional gripper driving means. [Figure 4]5A to 5C are diagrams illustrating the operation of a torque control means in the gripper driving means of the first embodiment. [Figure 5] 10A and 10B are diagrams illustrating the configuration of a gripper driving means in a part gripping device according to a second embodiment. [Figure 6] FIG. 10 is a diagram showing the configuration of a part gripping device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, the present invention will be described in detail with reference to examples. [Example]

[0016] FIG. 1 is a diagram illustrating the overall configuration of a component mounting apparatus to which a component holding device according to a first embodiment is applied, and FIG. 2 is a diagram illustrating the configuration of the component holding device according to the first embodiment. As shown in FIG. 1, the component mounting device 1 includes an X-axis movement means 3 for moving the component gripping device 2 in the X-axis direction, a Y-axis movement means 4 for moving the X-axis movement means 3 in the Y-axis direction, a gripper storage means 6 for stocking various grippers 5 to be attached to the component gripping device 2, and a component providing means 9 for providing components 8 to be attached to a board 7.

[0017] FIG. 2 is a diagram illustrating a configuration of the part holding device 2 according to the first embodiment. As shown in Figure 2, the part holding device 2 of Example 1 is equipped with a gripper holding means 10 that detachably holds a gripper 5 consisting of a left chuck portion 11 and a right chuck portion 12, a rotation means 13 that rotates the gripper holding means 10 around a central axis C, a Z-axis movement means 14 that moves the gripper holding means 10 and the rotation means 13 in the Z-axis direction (up and down direction), and a gripper drive means 15 that opens and closes the left chuck portion 11 and the right chuck portion 12. The rotation means 13 is composed of a rotation block 16 extending upward from the center of the upper surface of the gripper holding means 10 along the central axis C, a rotation support part 17 fixed to the Z-axis movement means 14 and rotatably supporting the rotation block 16, and a rotation motor 18 that rotates the rotation block 16 in both forward and reverse directions. In addition, the Z-axis movement means 14 is composed of a lifting section 19 to which the rotation support section 17 is fixed, a sliding holding section 20 that holds the lifting section 19 so that it can slide in the Z-axis direction, and a lifting motor 21 that moves the lifting section 19 in the Z-axis direction. Furthermore, the gripper drive means 15 is composed of a ball screw 22, an opening / closing motor (not shown) that rotates the ball screw 22 in both forward and reverse directions, a left moving block 23 and a right moving block 24 that move toward each other when the ball screw 22 rotates in the forward direction and move away from each other when the ball screw 22 rotates in the reverse direction, a linear guide 25 that slidably supports the left chuck portion 11 and the right chuck portion 12, and a torque control means that controls the torque of the opening / closing motor, and the left chuck portion 11 and the right chuck portion 12 move along the linear guide 25 in accordance with the movement of the left moving block 23 and the right moving block 24, respectively, thereby opening and closing the gripper 5.

[0018] The procedure for mounting the component 8 on the board 7 using the component gripping device 2 is as follows. (Step 1) The X-axis direction moving means 3 and the Y-axis direction moving means 4 are actuated to move the gripper 5 directly above the component 8 placed on the component providing means 9. (Step 2) The opening / closing motor is operated to rotate the ball screw 22 in the reverse direction, moving the left chuck portion 11 and the right chuck portion 12 away from each other, and opening the gripper 5. (Step 3) The rotation motor 18 is operated, and once the orientation of the gripper 5 is aligned with the orientation of the component 8 placed on the component providing means 9, the rotation motor 18 is stopped. (Step 4) The lifting motor 21 is activated, the lifting section 19 is lowered, and the open gripper 5 is lowered, and the gripper 5 is stopped just before the lower end of the gripper 5 comes into contact with the component providing means 9. (Step 5) The opening / closing motor is activated, the ball screw 22 is rotated forward to bring the left chuck portion 11 and the right chuck portion 12 closer to each other, and the gripper 5 grips the part 8. (Step 6) The lifting motor 21 is operated to raise the lifting unit 19 and raise the gripper 5 to a predetermined position. (Step 7) The X-axis direction moving means 3 and the Y-axis direction moving means 4 are actuated to move the gripper 5 holding the component 8 to directly above the component mounting position on the board 7. (Step 8) The lifting motor 21 is operated to lower the lifting unit 19, which lowers the gripper 5, and the component 8 is placed on the board 7. (Step 9) Activate the opening / closing motor and rotate the ball screw 22 in the reverse direction to move the left chuck portion 11 and the right chuck portion 12 away from each other. Once the gripper 5 is gradually opened and separated from the placed component 8, the opening / closing motor is stopped. (Step 10) When the opening / closing motor has stopped, the lifting motor 21 is activated to raise the lifting section 19 and raise the gripper 5 to a predetermined position. Thereafter, by repeating the above-mentioned (Step 1) to (Step 10), the components 8 placed on the component providing means 9 can be mounted onto the board 7 in sequence.

[0019] Furthermore, the procedure for replacing the gripper 5 held by the gripper holding means 10 in order to match the size of the component 8 to be mounted on the board 7 is as follows. (Step A) The X-axis direction moving means 3 and the Y-axis direction moving means 4 are actuated to move the gripper 5 to directly above the empty area of ​​the gripper storage means 6 (the left end in FIG. 1). (Step B) The opening / closing motor is activated, the ball screw 22 is rotated forward to bring the left chuck portion 11 and the right chuck portion 12 closer to each other, and the gripper 5 is put into a closed state. (Step C) Activate the lifting motor 21, lower the lifting section 19, and lower the closed gripper 5. Once it is placed in an empty space in the gripper storage means 6, the descent is stopped and the gripper 5 is detached from the gripper holding means 10. (Step D) The lifting motor 21 is operated to raise the lifting section 19 and raise the gripper holding means 10. (Step E) The part gripping device 2 is moved by the X-axis direction moving means 3, and the gripper holding means 10 is moved to directly above the gripper 5 to be used that is in the gripper storage means 6. (Step F) The lifting motor 21 is operated, the lifting section 19 is lowered, the gripper holding means 10 is lowered, and the gripper holding means 10 is stopped after being coupled with the gripper 5 to be used. (Step G) The lifting motor 21 is activated to raise the lifting unit 19 and raise the gripper 5 to a predetermined position.

[0020] The configurations and usage procedures of the component mounting device 1 and the component holding device 2 are as described above, but the present invention aims to prevent the grip load from becoming unstable due to prying of the gripper driving means 15 when the chuck sections 11 and 12 collide with the component 8, to easily control torque regardless of the degree and speed of opening and closing of the chuck sections 11 and 12, to prevent free rotation and vibration caused by lost motion generated in the gripper driving means 15, and to extend the life of the Z-axis moving means 14 and the rotating means 13 and prevent a decrease in operating accuracy, so the configuration that solves these problems will be described below.

[0021] Fig. 3 is a diagram illustrating the operation of a torque control means in a conventional gripper drive means, and Fig. 4 is a diagram illustrating the operation of the torque control means in the gripper drive means 15 of Example 1. As described above, both the conventional gripper drive means and the gripper drive means 15 of Example 1 are made up of a ball screw 22, an opening / closing motor (not shown) that rotates the ball screw 22 in both forward and reverse directions, a left moving block 23 and a right moving block 24 that move toward each other when the ball screw 22 rotates forward and move away from each other when the ball screw 22 rotates backward, a linear guide 25 that slidably supports the left chuck portion 11 and the right chuck portion 12, and a torque control means that controls the torque of the opening / closing motor, and since the configurations are exactly the same except for the torque control means, the same reference numerals as in Example 1 are used in Fig. 3 as well.

[0022] 3 shows a state in which the torque of the opening / closing motor is controlled by a conventional torque control means to cause the gripper 5 to grip a component 8. That is, after the open gripper 5 is positioned on both sides of the component 8 as shown in FIG. 3(A), the torque of the opening / closing motor is set to a predetermined torque To1 as shown in FIG. 3(C). Then, the ball screw 22 rotates forward, the left chuck portion 11 and the right chuck portion 12 move closer to each other, and the component 8 is gripped by the gripper 5 as shown in FIG. 3(B). Furthermore, the torque of the opening / closing motor is maintained at the predetermined torque To1 thereafter as shown in FIG. 3(C), so the component 8 is held by the gripper 5. However, when the left chuck portion 11 or the right chuck portion 12 collides with the part 8, a load is applied to the gripper drive means, causing twisting and increasing sliding resistance, which may cause one or more of the left moving block 23, the right moving block 24, the left chuck portion 11, and the right chuck portion 12 to assume an abnormal position as shown in Figure 3(B), making the grip load unstable.

[0023] Therefore, in the torque control means of the gripper drive means 15 of Example 1, when a prying motion occurs in the same manner as described with reference to FIG. 3 and one or more of the left moving block 23, the right moving block 24, the left chuck 11, and the right chuck 12 assume an abnormal position as shown in FIG. 4(A), the torque of the open / close motor is temporarily controlled to 0 (for example, 5 milliseconds) as soon as the left chuck 11 or the right chuck 12 collides with the component 8 as shown in FIG. 4(D). This momentarily turns the servo of the open / close motor off, eliminating the prying motion. As shown in FIG. 4(B), the perpendicularity between the left moving block 23 and the right moving block 24 and the ball screw 22, and the perpendicularity between the left chuck 11 and the right chuck 12 and the linear guide 25 return to normal. Thereafter, when the torque of the open / close motor is controlled to a predetermined torque To1 as shown in FIG. 4(D), the open / close motor is again turned on, thereby stably maintaining the component clamping force of the left chuck 11 and the right chuck 12. The collision between the left chuck portion 11 or the right chuck portion 12 and the component 8 can be detected by a mechanical detection means (such as a touch sensor) or an optical detection means (such as a light emitting / receiving element). [Example]

[0024] Fig. 5 is a diagram illustrating the configuration of endless belt type gripper driving means 26 in a part gripping device according to Example 2. Gripper driving means 15 in Example 1 was made up of ball screw 22, left moving block 23 and right moving block 24 that move toward or away from each other by rotation of an opening / closing motor, linear guide 25, and torque control means, but in Example 2, in order to prevent free rotation and vibration caused by lost motion occurring in gripper driving means 15, endless belt type gripper driving means 26 shown in Figs. 5(A) to 5(C) is used instead of gripper driving means 15 in Example 1. The components other than the endless belt type gripper driving means 26, that is, the rotating means 13, the Z-axis direction moving means 14, etc., are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0025] The endless belt-type gripper drive means 26 of the second embodiment uses, instead of the ball screw 22 of the first embodiment, an endless belt 28 that moves in one direction and the other by an opening / closing motor 27 with a bevel gear provided on the back side of the gripper. A left moving block 29 is provided below the endless belt 28, and a right moving block 30 is provided above it. When the endless belt 28 is moved in one direction (the lower belt is moved to the right in FIG. 5), the left moving block 29 moves to the right and the right moving block 30 moves to the left, so that the left chuck portion 31 and the right chuck portion 32 move closer to each other along the linear guides 33. Conversely, when the endless belt 28 is moved in the other direction (the lower belt is moved to the left in FIG. 5), the left moving block 29 moves to the left and the right moving block 30 moves right, so that the left chuck portion 31 and the right chuck portion 32 move away from each other along the linear guides 33. Conventionally, in such mechanisms, as shown in Figures 5(D) and (E), a compression spring or tension spring is provided on the endless belt 28 to constantly apply a load to the drive unit and prevent free rotation and vibration due to lost motion. In Figures 5(D) and (E), a compression spring 34 is provided on the endless belt 28, which urges the lower side of the endless belt 28 in one direction (to the right in Figure 5), so that a load is always applied in one direction. However, the load applied by the compression spring or tension spring varies depending on whether the left chuck portion 31 and the right chuck portion 32 are in a closed state approaching each other as shown in FIG. 5(D) or in an open state where the left chuck portion 31 and the right chuck portion 32 are in a separated state as shown in FIG. 5(E), which can result in insufficient prevention of spinning or vibration due to lost motion.

[0026] Therefore, in the second embodiment, instead of the compression spring 34 shown in Figures 5(D) and (E), an air spring 35 is provided on the endless belt 28, and a load is applied to the lower side of the endless belt 28. Therefore, when the endless belt 28 is moved in the other direction from the state shown in Figure 5(B) to the state shown in Figure 5(C), a constant load is applied in one direction, and when the endless belt 28 is moved in one direction from the state shown in Figure 5(C) to the state shown in Figure 5(B), a constant load is applied in the other direction. In other words, a constant load is applied to the drive unit in either case, thereby reliably preventing free rotation and vibration due to lost motion. Note that the air spring 35 may also be used to apply a constant load to the upper side of the endless belt 28. [Example]

[0027] FIG. 6 is a diagram showing the configuration of a part gripping device 2' according to the third embodiment. As described above, the part holding device 2 of Example 1 was equipped with a rotation means 13 that rotates the gripper holding means 10 around the central axis C, a Z-axis movement means 14 that moves the gripper holding means 10 and the rotation means 13 in the Z-axis direction, and a gripper drive means 15 that opens and closes the left chuck portion 11 and the right chuck portion 12 (see Figure 2). However, particularly in a part gripping device that handles a variety of parts, the travel distance of Z-axis direction moving means 14 needs to be increased to accommodate parts of different heights. However, the longer the travel distance, the farther the connection point between lifting unit 19 and sliding holding unit 20 (directly below the down arrow in FIG. 2, hereinafter referred to as the "lifting unit application point") becomes from the center of gravity of the part held by gripper 5 (directly below the C-axis in FIG. 2, hereinafter referred to as the "load application point"), and the greater the moment load applied to the lifting unit application point becomes. This causes problems such as a shorter lifespan of rotation means 13 and Z-axis direction moving means 14, an inability to handle heavy parts, and reduced operational accuracy. Therefore, in Example 3, in order to improve the lifespan of the rotation means 13 and the Z-axis direction moving means 14, to accommodate heavy components (high loads), and to improve operating accuracy, a peripherally arranged rotation means 36 and a centrally arranged Z-axis direction moving means 37 shown in Figure 6 are used instead of the rotation means 13 and the Z-axis direction moving means 14 (see Figure 2) of Example 1. Furthermore, the components other than the peripherally arranged rotation means 36 and the centrally arranged Z-axis direction movement means 37, i.e., the gripper holding means 10, the left chuck portion 11, the right chuck portion 12, and the gripper drive means 15 for opening and closing the left chuck portion 11 and the right chuck portion 12, are the same as those in Example 1, so their explanation will be omitted and they will be explained using the same numbers as in Example 1 (Figure 2).

[0028] The peripherally arranged rotation means 36 of Example 3 is composed of a cylindrical portion 38 that is fixedly arranged around a central axis extending in the direction indicated by the arrow in Figure 6, a rotating portion 39 that is rotatably supported inside the cylindrical portion 38, an upper annular support portion 40 that is fixed to the upper side of the inner wall of the cylindrical portion 38 and rotatably supports the rotating portion 39, a lower annular support portion 41 that is fixed to the lower end of the inner wall of the cylindrical portion 38 and rotatably supports the rotating portion 39, a circular rotating portion drive motor 42 that is fixed to the upper part of the cylindrical portion 38 and drives the rotating portion 39, a drive force transmission portion 43 that transmits the drive force of the rotating portion drive motor 42 to the rotating portion 39, and a cylindrical support portion 44 that is fixed to the lower part of the inner wall of the rotating portion 39 and supports the centrally arranged Z-axis direction moving means 37. The centrally positioned Z-axis direction moving means 37 is composed of a cylindrical linear guide 45 fixed to a cylindrical support portion 44, a cylindrical sliding portion 46 supported so as to slide freely on the inner wall of the cylindrical linear guide 45 and supporting the gripper holding means 10 at its lower end, a screw hole 47 provided along the central axis in the center of the upper surface of the cylindrical sliding portion 46, and a screw portion rotation motor 49 fixed to the upper end of the cylindrical linear guide 45 and rotating the screw portion 48 forward and backward. The screw portion 48 is threaded into the screw hole 47, and when the screw portion 48 rotates forward, the cylindrical sliding portion 46 descends along the cylindrical linear guide 45, and when the screw portion 48 rotates backward, the cylindrical sliding portion 46 ascends along the cylindrical linear guide 45.

[0029] Since the peripherally arranged rotation means 36 and the centrally arranged Z-axis direction moving means 37 are arranged and configured as described above, the point of application of the lifting unit in Example 1 is the portion indicated by the downward arrow in Fig. 6 (the center of the screw hole 47), and the point of application of the load in Example 1 is the portion indicated by the upward arrow in Fig. 6 (the center between the left chuck portion 11 and the right chuck portion 12). In other words, since both portions are coaxial, no moment load is generated, and no torque that would distort the peripherally arranged rotation means 36 and the centrally arranged Z-axis direction moving means 37 is applied. Therefore, according to the third embodiment, it is possible to improve the life span of the peripherally arranged rotation means 36 and the centrally arranged Z-axis direction movement means 37, to cope with high loads, and to improve the operation accuracy.

[0030] Modifications of Examples 1 to 3 are listed below. (Variant 1) The component gripping devices of Examples 1 and 2 have a rotation means 13, but if the orientation of the component 8 to be mounted on the board 7 is constant, there is no need to rotate the gripper 5, so the rotation means 13 may not be provided. (Variation 2) In the torque control means of Example 1, the torque of the opening / closing motor is temporarily set to 0 (for example, for 5 milliseconds) at the same time as the left chuck portion 11 or the right chuck portion 12 collides with the component 8, and then controlled to a predetermined torque To1, but the time for which the torque of the opening / closing motor is set to 0 is not limited to 5 milliseconds and should be adjusted appropriately depending on the size and weight of the component 8, left chuck portion 11, right chuck portion 12, ball screw 22, left moving block 23, right moving block 24, linear guide 25, etc. In most cases, this time is generally within the range of 3 to 10 milliseconds. Furthermore, instead of temporarily setting the torque of the opening / closing motor to 0, the torque may be temporarily reduced. The following methods (1) to (4) can be mentioned as ways of reducing the torque. (1) At the same time that the left chuck part 11 or the right chuck part 12 collides with the part 8, the torque is reduced to a constant value of 10% to 25% of the predetermined torque To1 (hereinafter referred to as "reduced torque To2"). (2) At the same time that the left chuck portion 11 or the right chuck portion 12 collides with the part 8, the torque is changed within the range of 0 to the reduction torque To2. (3) When the optical detection means detects that the distance between the left chuck portion 11 or the right chuck portion 12 and the part 8 has reached a predetermined distance, the torque is reduced to To2. (4) When the optical detection means detects that the distance between the left chuck portion 11 or the right chuck portion 12 and the part 8 has reached a predetermined distance, the torque is changed within the range of 0 to the reduced torque To2.

[0031] (Variant 3) The peripherally arranged rotating means 36 of Example 3 was provided with a cylindrical portion 38 fixedly arranged around the central axis, but as long as it can support the rotating portion 39 rotatably, it may be not only cylindrical but also rectangular, arc-shaped or flat. (Variant 4) The peripherally arranged rotation means 36 of Example 3 was equipped with an upper annular support portion 40 and a lower annular support portion 41, but it does not have to be annular as long as the periphery of the rotating portion 39 is supported at multiple points and the rotating portion 39 can rotate around a central axis. (Modification 5) The rotating part drive motor 42 in the third embodiment is annular, but it does not have to be annular as long as it can transmit driving force to the rotating part 39 at one or more points around the rotating part 39. (Variant 6) The centrally-placed Z-axis direction moving means 37 of Example 3 was equipped with a cylindrical linear guide 45 and a cylindrical sliding part 46, but these are not limited to being cylindrical, and may be in the shape of a square tube or a flat plate as long as they can move the gripper 5 and gripper driving means 15 in the vertical direction and rotate around a central axis. (Variation 7) The cylindrical sliding portion 46 of the center-disposed Z-axis direction moving means 37 of Example 3 descends when the screw portion 48 rotates forward and ascends when it rotates backward, but the mechanism for raising and lowering the cylindrical sliding portion 46 of Example 3 or the square-tube sliding portion or flat-plate sliding portion of Variation 6 may have any configuration. For example, the cylindrical sliding portion 46 or the like may be slid up and down by a linear motor, or the cylindrical sliding portion 46 or the like may be slid up and down by a mechanism that converts rotational motion into linear motion (such as a rack and pinion). [Explanation of symbols]

[0032] 1 Component mounting device 2 Component gripping device according to embodiment 1 2' Part gripping device according to embodiment 3 3 X-axis direction moving means 4 Y-axis direction moving means 5 Gripper 6 Gripper storage means 7 substrate 8 component 9 component providing means 10 gripper holding means 11 left chuck portion 12 right chuck portion 13 rotation means 14 Z-axis direction moving means 15 Gripper driving means 16 Rotation block 17 Rotation support part 18 Rotation motor 19 Lifting part 20 sliding holding part 21 lifting motor 22 ball screw 23 Left moving block 24 Right moving block 25 Linear guide 26 Endless belt type gripper drive means 27 Opening and closing motor with bevel gear 28 Endless belt 29 Left moving block 30 Right moving block 31 Left chuck 32 Right chuck 33 Linear guide 34 Compression spring 35 Air spring 36 Peripheral arrangement type rotation means 37 Central arrangement type Z-axis direction movement means 38 cylindrical portion 39 rotating portion 40 upper annular support portion 41 Lower annular support portion 42 Rotating portion drive motor 43 Driving force transmission portion 44 cylindrical support portion 45 cylindrical linear guide 46 cylindrical sliding portion 47 Screw hole 48 Screw part 49 Motor for rotating the screw part

Claims

1. A part gripping device including a gripper for gripping a part and a gripper driving means for opening and closing the gripper, The gripper driving means a motor that drives the gripper in an opening direction and a closing direction; and a torque control means for driving the gripper in a closing or opening direction, and for temporarily reducing the torque generated by the motor immediately after the chuck portion of the gripper collides with the part, and then controlling the torque to a predetermined value. A part gripping device characterized by:

2. The torque control means temporarily sets the torque generated by the motor to zero, and then controls the torque to a predetermined value.

2. The part gripping device according to claim 1.

3. The torque control means controls the torque generated by the motor to a predetermined torque after setting the torque generated by the motor to 0 for a certain period of time, regardless of the degree of opening or closing and the opening / closing speed of the chuck portion.

3. The part holding device according to claim 2.

4. The gripper driving means includes a conversion mechanism that converts the rotational force of the motor into a force that causes the gripper to open and close in a straight line; and an air spring that applies a constant force to the conversion mechanism in the opening or closing direction of the gripper.

4. The part holding device according to claim 1, wherein the part holding device is a part holding device.

5. The part holding device includes a Z-axis direction moving means for moving the gripper and the gripper driving means in a vertical direction, and a rotation means for rotating the gripper, the gripper driving means, and the Z-axis direction moving means around a central axis. the Z-axis direction moving means is disposed above a central portion of the gripper, The rotating means is disposed around the Z-axis direction moving means.

4. The part holding device according to claim 1, wherein the part holding device is a part holding device.

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