JP7804445B2 - Gripper - Google Patents

Description

The present invention relates to grippers that primarily grip small or fragile parts, and in particular to grippers that can be positioned while gripping a part.

Conventionally, grippers capable of gripping fragile parts and fine-tuning gripping force have been known in which the two gripping jaws, one on each side, can be driven independently. For example, Patent Document 1 discloses technology for adjusting the gripping position and gripping force by controlling the drive of a first jaw and a second jaw, which can move independently, using a first actuator and a second actuator, respectively.

Japanese Unexamined Patent Publication No. 62-120990

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. Therefore, there is also a demand for miniaturization of grippers used in automated machines and robots to accommodate the size of the parts to be gripped and the small gripping force required.

In the gripper disclosed in 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.

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 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,
The first actuator and the second actuator are each located at offset positions within the housing in a direction perpendicular to the movement direction of the first claw and the second claw, and are located above each pair of the linear guide blocks .

This invention allows the gripper body to be made smaller.

FIG. 1 is a perspective view showing the overall appearance of a gripper according to the present invention; A perspective view showing the internal configuration of the gripper A perspective view showing only the main parts inside the gripper A perspective view showing the configuration of a linear guide 1A and 1B are diagrams showing the internal structure of the gripper, in which (A) is a front view, (B) is a side view, (C) is a cross-sectional view taken along line A-A in the front view A, and (D) is a cross-sectional view taken along line B-B in the side view B. 1A and 1B are diagrams showing the configuration of a slide member, in which FIG. 1A is a perspective view and FIG. 1B is an exploded perspective view. FIG. 10 is an exploded perspective view showing a method for assembling the slide member into the housing. A bottom view showing the arrangement of the gripper drive unit

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>

Figure 1 is a perspective view showing the entire gripper according to the present invention. Figure 2 is a perspective view showing the internal structure of the gripper. Figure 3 is a perspective view showing only the main internal parts of the gripper.

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 are 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 housed 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.

A pair of linear guides 8 are arranged on the underside of the housing 7 shown in Figure 2, parallel to the direction of movement of the first and second claws 4 and 5 and facing each other in the Y direction. Figure 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 the 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.

As shown in Figure 2, a printed circuit board 9 is fixed to the upper side of the housing 7. Various connectors, including a wiring connector 6, as well as a first photointerrupter 10 and a second photointerrupter 11 are mounted on both sides of the printed circuit board 9 (neither of which are shown in Figure 2).

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, respectively, with screws. The shapes of the first claw 4 and the second claw 5 can be changed depending on the object to be grasped. 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, respectively, with multiple screws 14 (see Figure 5).

5A and 5B are diagrams showing the internal structure of the gripper, where (A) is a front view, (B) is a side view, (C) is a cross-sectional view taken along line A--A in the front view A, and (D) is a cross-sectional view taken along line B--B in the side view B.
As shown in Figure 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.

Figure 6 shows the configuration of the first slide member 12 and 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, 122 and tapped holes 123, 124. The first nut member 17 is formed with a nut portion 171, a hole 172 corresponding to the dowels 121, 122 of the first slide member 12, an elongated hole 173, and screw holes 174, 175 corresponding to the tapped holes 123, 124. A protrusion 176, which serves as the detection target corresponding to the first photointerrupter 10, is also integrally formed. The first slide member 12 and first nut member 17 are connected and fixed with screws 19 after being positioned. The same applies to the second slide member 13 and second nut member 18.

As shown in Figure 5, the first motor 15 and the second motor 16 are mounted in two motor mounting through-holes 74, 75 that fit into the protrusions 154, 164 of the motor flanges 153, 163, respectively, at a predetermined distance from different sides of the 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 housing 7 with screws through the screw mounting holes in the flanges 153, 163.

The tips of the output shafts 151, 161 are rotatably supported via bearings 21, 22, which are fixed coaxially to the motor mounting through-holes 74, 75 in the housing 7. Furthermore, threaded portions 155, 165 are formed at the tips of the output shafts 151, 161, and are threadedly engaged with hex nuts 23, 24, respectively. This brings the hex nuts 23, 24 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.

Based on the above-described configuration, the gripper 1 of this embodiment can independently move the first jaw 4 and the second jaw 5 in the linear direction (opening and closing operations) by rotating the first motor 15 and the second motor 16, respectively.

First, by rotating the first motor 15 and the second motor 16 clockwise (CW) as viewed from the output shaft side of the motors, the first claw 4 and the second claw 5 move outward (away from each other). As shown in Figure 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, thereby detecting the origin reference positions of the first claw 4 and the second claw 5 and performing a return-to-origin operation.

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.

By independently controlling the direction and amount of rotation of the first motor 15 and the second motor 16 within the range of motion of the first claw 4 and the second claw 5, it is possible to adjust the gripping position and gripping force of an object. In other words, by moving the position of each claw while the first claw 4 and the second claw 5 are gripping an object, it is possible to move the position of the object or adjust the strength of the gripping force applied by the claws to the object.

Note that while the position control of each claw is based on open-loop control using a stepping motor, it is also possible to install an encoder on the output shaft of each motor and indirectly detect the position of each claw using the encoder to control positioning.

In the gripper 1 of this embodiment, as shown in the bottom view of Figure 8, which shows the arrangement of the gripper drive unit, the first motor 15 and second motor 16, which are the drive means for the first jaw 4 and second jaw 5, are installed at positions offset in the Y direction, which is perpendicular to the movement direction of the jaws, from the center line of the jaws shown in Figure 8 (a line passing through the approximate centers of the first jaw 4 and second jaw 5 in the Y direction).

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, the motor 16 or 15 is arranged so that the threaded portion 152 or 162 of the lead screw on the output shaft of one motor is aligned with the threaded portion 152 or 162 of the lead screw on the output shaft of the other motor in the Y direction.

This configuration ensures a range of motion for the first slide member 12 and second slide member 13, to which the first claw 4 and second claw 5 are fixed, while effectively utilizing the space within the housing 7, thereby reducing the width of the housing 7 and making the gripper 1 more compact in the X direction.

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

If the offset direction is set in the Z direction instead of horizontally, as described above, the threaded portion 152 or 162 of one drive unit and the other lead screw will not be aligned in the Y direction, but will only expand in the Z direction, allowing for miniaturization in both the X and Y directions.

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 arranged approximately parallel to each other, rather than on both sides of a single wall.

In addition, in this embodiment, the slide member and nut member are configured as separate members, but the first slide member 12 and the second slide member 13 may be configured as an integrated part of 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.

However, by making them separate components, 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 a pair of linear guide blocks 82 with screws 14. Furthermore, the first nut member 17 is inserted straight into the opening 76 from the top side of the housing 7, positioned using the positioning means (dowels 121, 122, holes 172, and elongated holes 173) provided on the first slide member 12 and first nut member 17, and then fixed from the side with screws 19. The same applies to the second slide member 13 and second nut member 18.

By constructing the slide member and nut member as separate components in this way, the assembly workability of the gripper 1 is significantly improved.

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.

Furthermore, by using separate components, it is possible to select the appropriate material for each component. 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 a nut portion, can be made of a highly slidable resin.

In this embodiment, the driving means for driving the first jaw 4 and second jaw 5 of the gripper 1 is configured as lead screw threads 152, 162 formed integrally with the output shaft of the motor and a nut member that screws into the lead screw. However, this is not limited to this, and it may also be a linear motion mechanism such as a miniature ball screw, or a linear actuator such as an electric cylinder or a linear voice coil actuator.

REFERENCE SIGNS LIST 1 Gripper 4 First jaw 5 Second jaw 7 Housing 73 Central wall portion 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 portion 16 Second motor 162 Lead screw thread portion 17 First nut member 171 Nut portion 18 Second nut member 181 Nut portion

Claims (6)

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. 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. The gripper described in claim 1, wherein the first slide member and the second slide member have the same shape. 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. 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. A gripper described in any one of claims 1 to 5, characterized in that the first slide member and the second slide member are capable of moving independently.