JP7728148B2 - Grip device and industrial robot - Google Patents

Description

The present invention relates to a gripping body, a gripping device, and an industrial robot.

A known gripping device for gripping workpieces is one equipped with a bag-shaped gripping body (Patent Document 1). The gripping body of the gripping device disclosed in Patent Document 1 has a palm portion and multiple fingers protruding from the periphery of the palm portion. The gripping body has an opening at the other end opposite the end where the palm portion and fingers are provided, and is fixed to a case at a flange formed around the periphery of the opening, which seals the opening. The case is connected to a vacuum generator via piping. In the gripping device disclosed in Patent Document 1, when the pressure inside the gripping body is reduced, the palm portion deforms in the thickness direction, and the multiple fingers elastically deform so as to collapse toward the palm portion. This allows the multiple fingers to come into contact with the surface of the workpiece and grip the workpiece. This allows for easy and gentle gripping of soft workpieces such as food.

Patent Document 2 discloses a gripping device in which a band is wrapped around the outer periphery of the gripping body, and tightening this band more securely secures the gripping body to the case. The gripping device described in Patent Document 2 has a structure in which the band tightens the gripping body and the case, preventing the gripping body from falling off the case when the fingers elastically deform toward the palm as the palm deforms in the thickness direction.

JP 2018-062038 A Japanese Patent Application Laid-Open No. 2019-150892

The gripping device disclosed in Patent Document 2 has a step formed between the band and the gripping body, making it easy for liquid to pool at this step. Liquid pools are unhygienic because they can cause mold to grow. The gripping device disclosed in Patent Document 1 has a step formed between the flange portion formed around the periphery of the opening of the gripping body and the case, making it prone to liquid pooling, just like Patent Document 2.

The present invention aims to provide a gripping body, gripping device, and industrial robot that prevents the gripping body from falling off the case and prevents liquid pooling.

The gripping body of the present invention is a bag-shaped gripping body used in a gripping device that grips a workpiece, and includes a palm portion, a plurality of finger portions that protrude from the periphery of the palm portion and fall toward the palm portion by deforming the palm portion in the thickness direction, and an opening provided on the other end opposite the end where the palm portion and the plurality of finger portions are provided, the opening having an opening edge that defines the opening and an inner surface that curves toward the center of the opening.

The gripping device of the present invention comprises a case that is inserted into the opening and has the gripping body, a bottom, a cylindrical portion provided on the outer edge of the bottom, and a corner portion connecting the bottom and the cylindrical portion, the corner portion having an outer surface that curves toward the center of the case, and the inner surface and the outer surface are in contact.

The industrial robot according to the present invention is equipped with the above-described gripping device.

According to the present invention, the opening of the grip body has an inner surface that curves toward the center of the opening, and the corners of the case have outer surfaces that curve toward the center of the case. The inner surface of the opening and the outer surfaces of the corners are in contact with each other, preventing the grip body from falling off the case and preventing liquid from pooling.

1 is a schematic diagram illustrating an example of an industrial robot to which a gripping device according to an embodiment is applied. FIG. 2 is a partial cross-sectional view showing a gripping device according to an embodiment. FIG. 10 is a perspective view showing a state in which the case is being removed from the opening of the grip body. FIG. 10 is a cross-sectional view showing a state in which the case is being removed from the opening of the grip body. FIG. 10 is a cross-sectional view showing a state in which the case is inserted into the opening of the grip body. FIG. 2 is a partial cross-sectional view showing a state in which the gripping device according to the embodiment is in use. FIG. 10 is an exploded perspective view showing a gripping device according to a modified example of the embodiment. FIG. 10 is a partial cross-sectional view showing a gripping device according to a modified example of the embodiment. FIG. 10 is a partial cross-sectional view showing a state in which a gripping device according to a modified example of the embodiment is used.

Embodiments of the present invention will be described in detail below with reference to the drawings. The embodiments and variations described below are examples of the present invention, and the present invention is not limited to these. In the following description of the embodiments and variations, similar components will be designated by similar reference numerals, and descriptions will be omitted where appropriate.

1. Embodiment (Overall Configuration)
1 shows the configuration of an industrial robot 12 to which a gripping device 10A according to this embodiment is applied. The industrial robot 12 is a Cartesian robot, and includes a rail 14, a moving body 16 that moves along the rail 14, and an air cylinder 18 fixed to the moving body 16. The rail 14 is provided so as to be movable in the Y-axis direction in the drawing.

The air cylinder 18 has a cylinder tube 19 and a piston rod 20 that is movable forward and backward relative to the cylinder tube 19. Pipes 21 and 22 are attached to the cylinder tube 19. Gas is supplied and exhausted through the pipes 21 and 22, allowing the piston rod 20 to move forward and backward relative to the cylinder tube 19. A gripping device 10A is attached to the tip of the piston rod 20 via a detachable part 24 connected to an adapter plate 23. The adapter plate 23 is fixed to the tip of the piston rod 20 with bolts (not shown).

The industrial robot 12 can grasp a workpiece W placed on a horizontal base 26 with the gripping device 10A and move it in the X-, Y-, and Z-axis directions.

Figure 2 shows a partial cross-sectional view of the gripping device 10A. Figure 2 shows the gripping device 10A detached from the detachable part 24. The gripping device 10A has a bag-shaped gripping body 28A that is attached to the piston rod 20 via the detachable part 24. The gripping body 28A can be made of a material that is airtight, elastic, and flexible, such as natural rubber, synthetic rubber, or various elastomers. The material of the gripping body 28A does not necessarily have to be a single material; it can also be a composite material made up of different materials. The hardness of the gripping body 28A, measured in accordance with the durometer hardness test (type A) of JIS K6253, is preferably approximately 60 to 90.

The grip body 28A comprises a palm portion 30, a plurality of finger portions 32 protruding from the periphery of the palm portion 30, and an opening 34 provided at the other end opposite the end where the palm portion 30 and the plurality of finger portions 32 are provided. The palm portion 30 is generally disk-shaped. The finger portions 32 are formed integrally with the palm portion 30, and two are provided to sandwich the palm portion 30. A predetermined gap is formed between the finger portions 32. Three or more finger portions 32 may be provided radially surrounding the palm portion 30.

The inner surface 32A of the finger portion 32 is formed integrally with the palm portion 30. The finger portion 32 is solid. The material of the finger portion 32 may be the same as or different from the material of the palm portion 30. Furthermore, it does not need to be uniform; it may be a composite material combining different materials, or may contain additives such as fillers.

The opening 34 is sealed by the case 40A. An internal space 29 is formed by the inner surface of the grip body 28A and the case 40A.

The case 40A is preferably made of metal such as stainless steel or hard resin such as plastic. The case 40A has a bottom 41, a cylindrical portion 42A provided on the outer edge of the bottom 41, and corner portions 43 connecting the bottom 41 and the cylindrical portion 42A. The bottom 41 is a plate-shaped member, and in this example, is formed in a disk shape. The cylindrical portion 42A is a cylindrical member, and in this example, is formed in a cylindrical shape. The bottom 41, the cylindrical portion 42A, and the corner portions 43 are integrally formed. The bottom 41 has a through-hole 44 that penetrates the bottom 41 in the thickness direction. A joint 45 is provided in the through-hole 44. The joint 45 is screwed to the bottom 41 via a sealing material 46. The joint 45 is detachably connected to the detachable portion 24 with a single touch.

The detachable portion 24 is a one-touch coupling, with one end connected to the adapter plate 23 and the other end connected to the coupling 45. The detachable portion 24 connects to the coupling 45 when the coupling 45 is inserted in the insertion direction, and is disconnected from the coupling 45 when the release portion 47 is pushed in the insertion direction. The detachable portion 24 is not limited to a one-touch coupling, and may be a coupling that connects to the coupling 45 with a screw.

The detachable unit 24 is provided with an intake and exhaust port 48. The intake and exhaust port 48 is connected to one end of a pipe (not shown). The other end of this pipe is connected to a vacuum generator such as a vacuum pump or vacuum ejector, for example, via a three-way valve. In this example, a vacuum pump is used as the vacuum generator. The three-way valve has a vacuum port, an intake and exhaust port, and an atmosphere release port. The vacuum port is connected to the vacuum pump, the intake and exhaust port is connected to the gripping device 10A, and the atmosphere release port is connected to the atmospheric pressure space. Gas flows from the internal space 29 to the vacuum pump and from the atmospheric pressure space to the internal space 29 through the pipe connected to the intake and exhaust port 48. The detachable unit 24 is fixed to the adapter plate 23 by screwing bolts into the adapter plate 23 through mounting holes (not shown) provided on the top surface.

The opening 34 of the grip body 28A has an opening edge 50 that defines the opening and an inner surface 51 that curves toward the center of the opening. The inner surface 51 of the opening 34 is a concave curved surface. The corner 43 of the case 40A has an outer surface 52 that curves toward the center of the case 40A. The outer surface 52 of the corner 43 is a convex curved surface. The inner surface 51 of the opening 34 and the outer surface 52 of the corner 43 are in contact. The contact between the concave inner surface 51 of the opening 34 and the convex outer surface 52 of the corner 43 generates friction between the inner surface 51 and the outer surface 52, causing the opening 34 of the grip body 28A to hook onto the corner 43 of the case 40A. This allows the grip body 28A to be attached to the case 40A without using a band. To prevent the grip body 28A from falling off, it is desirable for the entire inner surface 51 of the opening 34 and the entire outer surface 52 of the corner 43 to be in contact. The grip body 28A can be attached to the case 40A as long as at least part of the inner surface 51 of the opening 34 and at least part of the outer surface 52 of the corner 43 are in contact.

The opening 34 gradually becomes thinner toward the opening end 50 of the opening 34. In other words, the thickness of the opening 34 gradually decreases from one end of the gripping body 28A to the other end. As a result, the gripping device 10A does not have a step between the opening 34 of the gripping body 28A and the bottom 41 of the case 40A, and the opening 34 and the bottom 41 are smoothly connected.

The inner surface 51 of the opening 34 and the outer surface 52 of the corner 43 are both rounded fillets. When the case 40A is inserted into the opening 34, the curvature of the inner surface 51 of the opening 34 is the same as the curvature of the outer surface 52 of the corner 43. This brings the inner surface 51 of the opening 34 and the outer surface 52 of the corner 43 into contact over their entire surfaces, improving the frictional force caused by contact between the inner surface 51 and the outer surface 52. Note that "same" here does not only mean that the curvature of the inner surface 51 of the opening 34 and the curvature of the outer surface 52 of the corner 43 are completely identical, but also includes cases where they are approximately identical, or within a specified error range (e.g., an error range of a few percent) taking into account design errors, etc.

Figure 3 shows a perspective view of the case 40A being removed from the opening 34 of the grip body 28A. Figure 4 shows a cross-sectional view of the case 40A being removed from the opening 34 of the grip body 28A. Figure 5 shows a cross-sectional view of the case 40A being inserted into the opening 34 of the grip body 28A.

When the case 40A is removed from the opening 34, the curvature of the inner surface 51 of the opening 34 is greater than the curvature of the outer surface 52 of the corner 43 (see Figure 4). When the case 40A is inserted into the opening 34, the opening end 50 of the opening 34 expands along the outer surface of the tubular portion 42A of the case 40A (see Figure 5). When the case 40A is inserted into the opening 34, the opening end 50 of the opening 34 contracts along the outer surface 52 of the corner 43 of the case 40A. As a result, the inner surface 51 of the opening 34 and the outer surface 52 of the corner 43 come into contact over their entire surfaces, and as described above, the curvature of the inner surface 51 of the opening 34 becomes the same as the curvature of the outer surface 52 of the corner 43 (see Figure 2). When the case 40A is removed from the opening 34, the curvature of the inner surface 51 of the opening 34 is greater than the curvature of the outer surface 52 of the corner 43, so when the case 40A is inserted into the opening 34, the corner 43 of the case 40A is clamped by the opening 34 of the grip body 28A.

(Actions and Effects)
The operation and effects of the industrial robot 12 equipped with the gripping device 10A configured as described above will now be described. Note that the conditions shown below are merely examples. As shown in FIG. 1, the industrial robot 12 starts from an origin state in which the piston rod 20 is retracted into the cylinder tube 19 and the air cylinder 18 is contracted. In the initial state of the gripping device 10A, the pressure in the internal space 29 (see FIG. 2) of the gripping body 28A is atmospheric pressure. That is, the three-way valve connected to the intake and exhaust port 48 is in a state in which the intake and exhaust port is disconnected from the vacuum port and connected to the atmosphere release port.

The industrial robot 12 positions the gripping device 10A on the vertical line of the workpiece W placed on the base 26 by moving the mobile body 16 along the rail 14. Next, the industrial robot 12 extends the air cylinder 18 by advancing the piston rod 20 from the cylinder tube 19 until the finger portion 32 reaches the workpiece W.

The three-way valve is then switched so that the air supply/exhaust port is disconnected from the atmosphere release port and connected to the vacuum port. This causes the gripping device 10A to suck in gas from within the gripping body 28A through the piping, reducing the pressure in the internal space 29 of the gripping body 28A to, for example, -0.03 MPa or less.

As shown in Figure 6, the palm portion 30 is deformed in the thickness direction (Z direction) as if being sucked into the internal space 29. As the palm portion 30 deforms in the thickness direction, the inner surfaces 32A of the fingers 32 are pulled toward the center of the palm portion 30. At this time, the inner surface 51 of the opening 34 rubs against the outer surface 52 of the corner 43, causing the opening edge 50 of the opening 34 to move from the other end to one end of the gripping body 28A. As a result, the fingers 32 elastically deform so as to fall toward the palm portion 30 and come into contact with the surface of the workpiece W. In this way, the gripping device 10A reduces the pressure inside the gripping body 28A, causing the fingers 32 to close and grip the workpiece W.

The industrial robot 12 then retracts the piston rod 20 into the cylinder tube 19 and contracts the air cylinder 18, thereby lifting the workpiece W from the base 26. Furthermore, the industrial robot 12 can freely move the workpiece W horizontally by moving the moving body 16 along the rail 14 and by moving the rail 14 in the Y-axis direction.

After moving to the desired location, the industrial robot 12 extends the air cylinder 18 by advancing the piston rod 20 from the cylinder tube 19 until the workpiece W contacts the base 26. Next, the three-way valve is switched so that the air supply/exhaust port is disconnected from the vacuum port and connected to the atmosphere release port. This allows gas to flow from the atmosphere release port through the piping into the internal space 29 of the gripping body 28A. As the pressure in the internal space 29 of the gripping body 28A returns to atmospheric pressure, the palm 30 is pushed out and returns to its original state. At this time, the inner surface 51 of the opening 34 rubs against the outer surface 52 of the corner 43, causing the opening edge 50 of the opening 34 to move from one end to the other end of the gripping body 28A. This causes the fingers 32 to open and release the workpiece W.

The industrial robot 12 then retracts the piston rod 20 into the cylinder tube 19 and contracts the air cylinder 18, thereby detaching the gripping device 10A from the workpiece W. In this way, the industrial robot 12 can grip the workpiece W placed on the base 26 with the gripping device 10A and move it to the desired position.

In the gripping device 10A, the opening 34 of the gripping body 28A has an inner surface 51 that curves toward the center of the opening, and the corner 43 of the case 40A has an outer surface 52 that curves toward the center of the case 40A, with the inner surface 51 of the opening 34 and the outer surface 52 of the corner 43 coming into contact. This allows the opening 34 of the gripping body 28A to be hooked onto the corner 43 of the case 40A, making it possible to attach the gripping body 28A to the case 40A without using a band. Furthermore, because no band is used, there are no steps that could cause liquid to pool. Therefore, with the gripping device 10A, the gripping body 28A will not fall off the case 40A, and liquid pooling is prevented.

By not using bands, the gripping device 10A reduces the number of parts and eliminates the need for specialized tools to tighten the bands, thereby reducing manufacturing costs.

The gripping device 10A has an opening 34 that gradually becomes thinner toward the opening end 50, creating a smooth connection between the opening 34 of the gripping body 28A and the bottom 41 of the case 40A. Because the gripping device 10A has no steps between the gripping body 28A and the case 40A, liquid accumulation is more reliably prevented.

When the case 40A is inserted into the opening 34, the curvature of the inner surface 51 of the opening 34 is the same as the curvature of the outer surface 52 of the corner 43. In the gripping device 10A, the inner surface 51 of the opening 34 and the outer surface 52 of the corner 43 are in full contact with each other, thereby improving the friction between the inner surface 51 of the opening 34 and the outer surface 52 of the corner 43, and more reliably preventing the gripping body 28A from falling off the case 40A.

When the case 40A is removed from the opening 34, the curvature of the inner surface 51 of the opening 34 is greater than the curvature of the outer surface 52 of the corner 43. When the case 40A is inserted into the opening 34, the corner 43 of the case 40A is clamped by the opening 34 of the grip body 28A, and as described above, the curvature of the inner surface 51 of the opening 34 becomes the same as the curvature of the outer surface 52 of the corner 43. In this way, the grip device 10A more reliably prevents the grip body 28A from falling off the case 40A by clamping the corner 43 of the case 40A by the opening 34 of the grip body 28A.

2. Modifications Fig. 7 shows an exploded perspective view of a gripping device 10B according to a modification of the above embodiment, in which a part of a gripping body 28B constituting the gripping device 10B is cut away.

As shown in Figure 7, the gripping device 10B differs from the gripping device 10A (see Figure 3) according to the above embodiment in that the gripping body 28B has a rib 60 and the case 40B has a groove 62 that engages with the rib 60. In the gripping device 10B, the gripping body 28B is positioned relative to the case 40B by the engagement between the rib 60 and the groove 62.

The rib 60 is provided on the inner surface of the grip body 28B. The rib 60 is formed in a ring shape along the circumferential direction of the grip body 28B. In this example, the shape of the rib 60 is semicircular in cross section, but can be selected as appropriate, and may be, for example, semi-elliptical, triangular, rectangular, or trapezoidal in cross section.

The groove 62 is provided on the outer surface of the cylindrical portion 42B that constitutes the case 40B. The groove 62 is formed in a ring shape along the circumferential direction of the cylindrical portion 42B. In this example, the shape of the groove 62 is rectangular in cross section, but this can be selected as appropriate, and may be, for example, a rectangular cross section with rounded corners, a semicircular cross section, a semi-elliptical cross section, a triangular cross section, or a trapezoidal cross section.

As shown in Figure 8, the width W1 of the rib 60 is smaller than the width W2 of the groove 62. The width W1 of the rib 60 may be, for example, less than half the width W2 of the groove 62. In this example, in the initial state, the rib 60 is positioned at the center position in the width direction of the groove 62. Because the width W1 of the rib 60 is smaller than the width W2 of the groove 62, movement of the rib 60 within the groove 62 is permitted.

As shown in Figure 9, when a workpiece is gripped, that is, when the palm portion 30 deforms in the thickness direction (Z direction) and the fingers 32 elastically deform so as to fall toward the palm portion 30, the opening edge 50 of the opening 34 of the gripping body 28B moves from the other end to one end of the gripping body 28B, and the rib 60 moves within the groove 62 from the other end to one end.

When the workpiece is released, i.e., when the palm 30 and fingers 32 return to their original state, the opening edge 50 of the opening 34 of the gripping body 28B moves from one end to the other of the gripping body 28B, and the rib 60 moves from one end to the other within the groove 62, returning to its original position (see Figure 8).

In the gripping device 10B, the width W1 of the rib 60 is smaller than the width W2 of the groove 62, allowing the rib 60 to move within the groove 62 and operate smoothly.

The above describes embodiments and modifications, but the present invention is not limited to the above embodiments and modifications, and can be modified as appropriate within the spirit and scope of the present invention.

For example, the air intake/exhaust port 48 may be connected to a positive pressure source and a three-way valve via a switching valve. The positive pressure source may be a pump or the like that supplies positive pressure to the internal space 29. When the air intake/exhaust port 48 is connected to the positive pressure source, the internal space 29 can be pressurized. When the internal space 29 is pressurized by the positive pressure source, the palm portion 30 is deformed in the thickness direction (opposite the Z direction) as if being pushed from the internal space 29 toward the atmospheric pressure space. As the palm portion 30 deforms in the thickness direction, the fingers 32 elastically deform so as to collapse away from the palm portion 30. In other words, the fingers 32 can open. At this time, the inner surface 51 of the opening 34 rubs against the outer surface 52 of the corner 43, and the opening edge 50 of the opening 34 moves from one end of the grip body to the other. Pressurizing the internal space 29 allows the fingers 32 to open to fit the size of the workpiece, improving versatility.

10A, 10B Grip device 12 Industrial robot 28A, 28B Grip body 30 Palm portion 32 Finger portion 34 Opening 40A, 40B Case 41 Bottom portion 42A, 42B Cylindrical portion 43 Corner portion 50 Open end 51 Inner surface 52 Outer surface 60 Rib 62 Groove

Claims (7)

A bag-shaped gripping body used in a gripping device that grips a workpiece,
A palm portion and
a plurality of finger portions provided to protrude from the periphery of the palm portion and tilting toward the palm portion by deforming the palm portion in a thickness direction;
an opening provided on the other end side opposite to the one end side on which the palm portion and the plurality of finger portions are provided,
The opening includes a grip body having an open end defining an opening and an inner surface curved toward a center of the opening ;
a case having a bottom, a cylindrical portion provided on an outer edge of the bottom, and a corner portion connecting the bottom and the cylindrical portion, the case being inserted into the opening;
Equipped with
the corner has an outer surface that curves toward the center of the case;
A gripping device in which the inner surface and the outer surface are in contact. The gripping device according to claim 1 , wherein the opening has a thickness that gradually decreases toward the open end. The gripping device according to claim 1 or 2 , wherein the curvature of the inner surface is the same as the curvature of the outer surface when the case is inserted into the opening. 4. The gripping device according to claim 1, wherein the curvature of the inner surface is greater than the curvature of the outer surface when the case is removed from the opening. The grip body has a rib,
The gripping device according to any one of claims 1 to 4 , wherein the case has a groove that engages with the rib. The gripping device according to claim 5 , wherein the width of the rib is smaller than the width of the groove. An industrial robot comprising the gripping device according to any one of claims 1 to 6 .