Gripper

Abstract

To downsize a gripper body in a gripper which can grip an object with a small gripping force by using a small-sized actuator for automatic assembly of fine parts.SOLUTION: A gripper includes: a first claw 4 and a second claw 5 for gripping an object; a first slide member 12 to which the first claw 4 is fastened, and which moves inside a housing 7 in a linear motion direction; a second slide member 13 to which the second claw 5 is fastened, and which moves inside the housing 7 in a linear motion direction; a first actuator for driving the first slide member 12; and a second actuator for driving the second slide member 13. The first actuator and the second actuator are off-set inside the housing 7 in a direction orthogonal to the direction of movement of the first claw 4 and the second claw 5.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gripper that mainly grips small or fragile parts, and more particularly to a gripper that can be positioned while gripping a part. [Background technology]

[0002] Conventionally, as a gripper capable of gripping fragile parts and finely adjusting the gripping force, a gripper in which two left and right jaws that form the gripping part can be driven independently has been known. For example, Patent Document 1 discloses a technology in which a first jaw and a second jaw that can move independently are driven and controlled by a first actuator and a second actuator, respectively, to adjust the gripping position and gripping force. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 62-120990 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, as various products have become smaller, there has been an increasing need for automated assembly of the fine parts that make up these products. As a result, there is a demand for grippers used in automated machines and robots to be smaller in size to accommodate the size of the parts to be gripped and the small gripping force required.

[0005] In the gripper of Patent Document 1, the screw shafts that engage with the first and second claws and the motors that rotate them are arranged on the same axis, which increases the space required to arrange the motors relative to the range of motion of each claw, resulting in an increase in the size of the gripper body. [Means for solving the problem]

[0006] In order to solve the above problems, the gripper according to the present invention comprises: a first claw and a second claw for gripping an object; a first slide member to which the first claw is fixed and which moves in a linear direction inside the housing; a second slide member to which the second claw is fixed and which moves in a linear direction inside the housing; a linear guide block constituting a linear guide arranged on the lower side of the housing in parallel with and facing the moving direction of the first claw and the second claw; a first actuator that drives the first slide member and a second actuator that drives the second slide member, a threaded portion of a lead screw for transmitting a driving force to the corresponding first slide member and the second slide member is coaxially and integrally formed on the output shaft of each of the first actuator and the second actuator; the first slide member and the second slide member are fixed to a pair of the linear guide blocks that face each other in a direction perpendicular to the moving direction of the first claw and the second claw, The first actuator and the second actuator are located at offset positions in the housing in a direction perpendicular to the direction of movement of the first claw and the second claw, respectively. and positioned above each pair of linear guide blocks. It is characterized by the following. [Effects of the Invention]

[0007] According to the present invention, the gripper body can be made smaller. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing the overall appearance of a gripper according to the present invention; [Figure 2] A perspective view showing the internal configuration of the gripper [Figure 3] A perspective view showing only the main parts inside the gripper [Figure 4] A perspective view showing the configuration of a linear guide [Figure 5] A diagram showing the internal structure of the gripper. (A) is a front view, (B) is a side view, (C) is an AA cross-sectional view in the front view A, and (D) is a B-B cross-sectional view in the side view B. [Figure 6]1A and 1B are diagrams showing the configuration of a slide member, in which (A) is a perspective view and (B) is an exploded perspective view. [Figure 7] FIG. 10 is an exploded perspective view showing a method for assembling the slide member into the housing. [Figure 8] A bottom view showing the arrangement of the gripper drive unit DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a gripper according to the present invention will be described with reference to the drawings. The gripper according to this embodiment is, for example, attached to the end of an arm of a manufacturing device such as an automatic machine or a robot, and is controlled by a control unit provided in the manufacturing device to grip a micro component and mount it on a product. <Embodiment>

[0010] Fig. 1 is a perspective view showing the entire gripper according to the present invention, Fig. 2 is a perspective view showing the internal configuration of the gripper, and Fig. 3 is a perspective view showing only the main parts inside the gripper.

[0011] 1, a gripper 1 according to one embodiment of the present invention has a generally rectangular parallelepiped shape and is housed between a lower cover 2 and an upper cover 3, with a first claw 4 and a second claw 5, which form gripping portions, protruding below the lower cover 2. A connector 6 for connecting wiring protrudes above the upper cover 3. The X, Y, and Z directions shown in FIG. 1 will be used in the following description. 2 and 3, a first motor 15 (first actuator) and a second motor 16 (second actuator) of the drive unit for independently driving the first jaw 4 and the second jaw 5 are accommodated and supported in a housing 7 inside the gripper 1. In this embodiment, the first jaw 4 and the second jaw 5 are identical components arranged symmetrically, and the configuration of the drive unit for the first jaw 4 is the same as the configuration of the drive unit for the second jaw 5.

[0012] A pair of linear guides 8 are arranged below the housing 7 shown in Fig. 2, parallel to the direction of movement of the first claw 4 and the second claw 5 and facing each other in the Y direction. Fig. 4 is a perspective view showing the configuration of the linear guides 8. Each of the pair of linear guides 8 is composed of a rail 81 and two linear guide blocks 82, 83 that are engaged and supported to share the rail 81 and move freely in a linear direction along the rail 81. The rails 81 are arranged parallel to each other along linear grooves 71, 72 formed in the housing 7, and are fixed from the outside into the grooves of the housing 7 with screws 84 via through holes 811 formed in the rails 81.

[0013] 2, a printed circuit board 9 is fixed to the upper side of the housing 7. On both sides of the printed circuit board 9, various connectors including a wiring connector 6, a first photointerrupter 10, and a second photointerrupter 11 are mounted (none of which are shown in FIG. 2).

[0014] The first claw 4 and the second claw 5 are connected and fixed to the first slide member 12 and the second slide member 13 with screws, respectively. The shapes of the first claw 4 and the second claw 5 can be changed depending on the object to be gripped. The first slide member 12 and the second slide member 13 have the same shape, and are connected and fixed to a pair of linear guide blocks 82 and 83 that face each other in a direction perpendicular to the movement direction of the first claw 4 and the second claw 5 with multiple screws 14 (see Figure 5).

[0015] FIG. 5 shows the internal structure of the gripper, where (A) is a front view, (B) is a side view, (C) is an AA cross-sectional view in the front view A, and (D) is a BB cross-sectional view in the side view B. As shown in Fig. 5, lead screw threads 152, 162 are integrally formed on the output shafts 151, 161 of the first motor 15 and the second motor 16, respectively. Mounting holes for fixing the motors are formed in the motor flanges 153, 163. Nuts formed on the first nut member 17 and the second nut member 18 are threadedly engaged with the lead screw threads 152, 162 of the output shafts 151, 161, respectively. The first nut member 17 and the second nut member 18 have the same shape and, like the first slide member 12 and the second slide member 13, are disposed opposite each other on the pair of linear guides 8.

[0016] FIG. 6 shows the configuration of the first slide member 12 and the first nut member 17, with (A) being a perspective view and (B) being an exploded perspective view. The first slide member 12 is provided with positioning dowels 121 and 122 and tapped holes 123 and 124. The first nut member 17 is formed with a nut portion 171, a hole 172 corresponding to the dowels 121 and 122 of the first slide member 12, an elongated hole 173, and screw holes 174 and 175 corresponding to the tapped holes 123 and 124. A protrusion 176 serving as a detection target corresponding to the first photointerrupter 10 is also integrally formed. The first slide member 12 and the first nut member 17 are connected and fixed with screws 19 after being positioned. The same applies to the second slide member 13 and the second nut member 18.

[0017] 5, the first motor 15 and the second motor 16 are mounted in two motor mounting through-holes 74, 75 that fit with protrusions 154, 164 of motor flanges 153, 163, respectively, at a predetermined distance from different sides of a central wall 73 that divides the interior of the housing 7. In this position, the first motor 15 and the second motor 16 are fixed to the inside of the housing 7 with screws that pass through the screw mounting holes in the flanges 153, 163.

[0018] The tip ends of the output shafts 151, 161 are rotatably supported via bearings 21, 22 that are respectively arranged and fixed coaxially in the motor mounting through holes 74, 75 of the housing 7. Furthermore, threaded portions 155, 165 are formed at the tip ends of the output shafts 151, 161, and are respectively threadedly engaged with hexagonal nuts 23, 24. As a result, the hexagonal nuts 23, 24 come into contact with the inner rings of the bearings 21, 22, restricting the movement of the output shafts 151, 161 in the thrust direction and preventing thrust rattle.

[0019] Based on the above-described configuration, the gripper 1 of this embodiment is capable of independently moving the first claw 4 and the second claw 5 in the linear direction (opening and closing operation) by rotating and driving the first motor 15 and the second motor 16, respectively.

[0020] First, by rotating the first motor 15 and the second motor 16 in a clockwise (CW) direction as viewed from the output shaft side of the motor, the first claw 4 and the second claw 5 move outward (away from each other). As shown in Fig. 5(D), the protrusions 176, 186 of the first nut member 17 and the second nut member 18 connected to the first slide member 12 and the second slide member 13 are detected by the first photointerrupter 10 and the second photointerrupter 11, whereby the origin reference positions of the first claw 4 and the second claw 5 are detected and an origin return operation is performed.

[0021] On the other hand, by rotating the first motor 15 and the second motor 16 counterclockwise (CCW) from the origin reference positions of the first claw 4 and the second claw 5, the first claw 4 and the second claw 5 move inward (toward each other), making it possible to grasp an object.

[0022] It is possible to adjust the gripping position and gripping force of an object by independently controlling the rotation direction and amount of rotational movement of first motor 15 and second motor 16 within the movable range of first claw 4 and second claw 5. In other words, by moving the position of each claw while the object is being gripped by first claw 4 and second claw 5, it is possible to move the position of the object or adjust the strength of the gripping force of the claws applied to the object.

[0023] The position control of each claw is based on open-loop control using a stepping motor, but it is also possible to provide an encoder on the output shaft of each motor and indirectly detect the position of each claw using the encoder to perform positioning control.

[0024] In the gripper 1 of this embodiment, as shown in the bottom view of Figure 8 showing the arrangement of the gripper drive unit, the first motor 15 and the second motor 16, which are the drive means for the first claw 4 and the second claw 5, are each installed at a position offset in the Y direction perpendicular to the movement direction of the claws from the center line of the claws shown in Figure 8 (a line passing through the approximate center of the first claw 4 and the second claw 5 in the Y direction).

[0025] The first motor 15 (first actuator) and the second motor 16 (second actuator) are arranged on different sides of the central wall 73 that divides the interior of the housing 7. In other words, in the Y direction, the motor 16 or 15 is arranged so that the threaded portion 152 or 162 of the lead screw of the output shaft of the other motor is aligned.

[0026] This configuration ensures the range of movement of the first slide member 12 and the second slide member 13 to which the first claw 4 and the second claw 5 are fixed, while effectively utilizing the space within the housing 7 to reduce the widthwise size of the housing 7 and make the gripper 1 smaller in the X direction.

[0027] The offset direction is not limited to the horizontal direction (Y direction) and may be in any direction. As for the amount of offset, it is desirable that the first claw 4 and the second claw 5 have the same shape, but they may be set to different amounts.

[0028] If the offset direction is set in the Z direction instead of the horizontal direction, as described above, one drive unit and the threaded portion 152 or 162 of the other lead screw will not be aligned in the Y direction, but they will only expand in the Z direction, making it possible to reduce the size in both the X and Y directions.

[0029] In this embodiment, the motors are arranged facing each other on both sides of the central wall 73 that divides the interior of the housing 7, but the central wall 73 may be a separate member from the housing 7. Furthermore, the motors may be arranged facing each other based on the outer surfaces of separate walls that are provided approximately parallel to each other, rather than on both sides of a single wall.

[0030] In addition, in this embodiment, the slide member and the nut member are constructed as separate members, but the first slide member 12 and the second slide member 13 may be formed as an integrated part with the first nut member 17 and the second nut member 18, and nut portions may be provided on the first slide member 12 and the second slide member 13.

[0031] However, by making them separate members, as shown in the exploded perspective view of Figure 7, when assembling the first slide member 12 into the housing 7, it can be inserted straight from below into the opening 76 on the lower side of the housing 7 and connected and fixed to the pair of linear guide blocks 82 with screws 14. Furthermore, the first nut member 17 is inserted straight into the opening 76 from the upper side of the housing 7, and after being positioned by positioning means (dowels 121, 122, hole 172, and elongated hole 173) provided on the first slide member 12 and first nut member 17, it is fixed from the side with screws 19. The same applies to the second slide member 13 and the second nut member 18.

[0032] By configuring the slide member and the nut member as separate members in this way, the workability of assembling the gripper 1 is improved significantly.

[0033] Furthermore, by using separate components, it is not necessary to widen the space between the linear guides 8 to accommodate the threaded portions 152 and 162 of the lead screws and the portions attached to the linear guide blocks 82 and 83, which are the thickest parts of the components, and therefore the size can be reduced in the Y direction.

[0034] Furthermore, by using separate members, it is possible to select the appropriate material for each member. For example, the slide members 12 and 13 can be made of a highly rigid metal, and the nut members 17 and 18, which have nuts, can be made of a highly slidable resin.

[0035] In this embodiment, the driving means for driving the first jaw 4 and the second jaw 5 of the gripper 1 is configured by threaded portions 152, 162 of a lead screw formed integrally with the output shaft of the motor and a nut member that screws into the threaded portions, but is not limited to this and may also be a linear actuator such as a miniature ball screw, an electric cylinder, or a linear voice coil actuator. [Explanation of symbols]

[0036] 1 Gripper 4 First Claw 5 Second Claw 7. Housing 73 Central wall 76 Lower opening 8 Linear Guide 81 Rail 82, 83 Linear guide block 12 First slide member 13 Second slide member 15 First motor 152 Lead screw thread 16 Second motor 162 Lead screw thread 17 First nut member 171 Nut part 18 Second nut member 181 Nut part

Claims

1. a first claw and a second claw for gripping an object; a first slide member to which the first claw is fixed and which moves in a linear direction inside the housing; a second slide member to which the second claw is fixed and which moves in a linear direction inside the housing; a linear guide block constituting a linear guide disposed on the lower side of the housing in parallel with and facing the moving direction of the first claw and the second claw; a first actuator that drives the first slide member and a second actuator that drives the second slide member, a threaded portion of a lead screw for transmitting a driving force to the corresponding first slide member and the second slide member is coaxially and integrally formed on the output shaft of each of the first actuator and the second actuator; the first slide member and the second slide member are fixed to a pair of linear guide blocks that face each other in a direction perpendicular to the moving direction of the first claw and the second claw, a gripper, characterized in that the first actuator and the second actuator are respectively positioned offset within the housing in a direction perpendicular to the direction of movement of the first jaw and the second jaw, and are positioned above each pair of the linear guide blocks.

2. 2. The gripper according to claim 1, wherein the first actuator and the second actuator are supported and fixed from opposite sides of a wall surface of a wall portion formed in a central portion of the housing that divides the interior of the housing.

3. The gripper according to claim 1 , wherein the first slide member and the second slide member have the same shape.

4. 2. The gripper according to claim 1, wherein the first actuator and the second actuator are motors that rotate the threaded portion of the lead screw.

5. 5. The gripper according to claim 4, wherein a nut member threadedly engaged with the threaded portion of the lead screw is configured as a separate member from the first slide member and the second slide member, and is fixed to the first slide member and the second slide member.

6. 6. The gripper according to claim 1, wherein the first slide member and the second slide member are capable of moving independently of each other.

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