Holding device

Abstract

To provide a holding device which can rotatably hold a holding object with a simple structure and hold the holding object in a constant attitude.SOLUTION: A holding device includes: a body; first and second holding parts which are supported by the body so as to relatively move close to and away from each other along a predetermined direction; and first and second contact parts which face each other in the predetermined direction and are respectively supported by the first and second holding parts so as to be rotatable around a predetermined direction. The first contact part is supported by the first holding part so as to be movable between a rotation allowable position an a rotation restriction position. The rotation allowable position is a position where the first contact part is separated from the first holding part and allowed to rotate relative to the first holding part. The rotation restriction position is a position where the first contact part contacts with the first holding part and the rotation is restricted relative to the first holding part.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a gripping device. [Background technology]

[0002] 2. Description of the Related Art There are known gripping devices that rotatably hold an object to be gripped (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-109271 A [Patent Document 2] JP 2019-202374 A [Patent Document 3] JP 2020-044596 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned gripping device, a complicated mechanism may be required to hold the gripping object in a fixed position, which may increase manufacturing costs and complicate control.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a gripping device that can rotatably hold an object to be gripped using a simple mechanism and can also hold the object to be gripped in a fixed posture. [Means for solving the problem]

[0006] The above object can be achieved by a gripping device comprising: a main body portion; first and second gripping portions supported on the main body portion so as to be movable toward and away from each other along a predetermined direction; and first and second abutment portions opposed to each other in the predetermined direction and supported on the first and second gripping portions, respectively, so as to be rotatable around the predetermined direction, wherein the first abutment portion is supported on the first gripping portion so as to be movable between a rotation allowable position and a rotation restricted position, the rotation allowable position being a position where the first abutment portion is separated from the first gripping portion and rotation is permitted relative to the first gripping portion, and the rotation restricted position being a position where the first abutment portion abuts against the first gripping portion and rotation is restricted relative to the first gripping portion. Effect of the Invention

[0007] A gripping device can be provided that can rotatably hold an object to be gripped using a simple mechanism and can also hold the object to be gripped in a fixed posture. [Brief description of the drawings]

[0008] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 2 is an external perspective view of a slide mechanism and a gripping portion. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 6 is a partially enlarged view of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] FIG. 1 is an external perspective view of the gripping device 1. The gripping device 1 includes a main body 10, a slide mechanism 30, gripping parts 50a and 50b, and abutting parts 70a and 70b. The main body 10 is substantially cylindrical with a central axis A as its center. The main body 10 has a base end 11 and a tip 12. The base end 11 is fixed to, for example, the arm of a robot. The slide mechanism 30 is fixed to the tip 12. The main body 10 supports the swinging parts 20a and 20b so that they can swing. The gripping parts 50a and 50b are supported by the slide mechanism 30 so that they can slide in a slide direction D. The slide direction D is substantially perpendicular to the central axis A. The abutting parts 70a and 70b face each other in the slide direction D. The slide direction D is an example of a predetermined direction. The contact portions 70a and 70b are supported by the gripping portions 50a and 50b, respectively, so as to be rotatable about a rotation axis B. The rotation axis B is substantially perpendicular to the central axis A. The contact portions 70a and 70b are each substantially disk-shaped.

[0010] 2 is an external perspective view of the main body 10. A single motor M for swinging the oscillating parts 20a and 20b is provided inside the main body 10. A mechanism such as gears for transmitting the power of the motor M to the oscillating parts 20a and 20b is provided inside the main body 10. The oscillating parts 20a and 20b are provided at positions shifted by 180° about the central axis A. Since the oscillating parts 20a and 20b are the same member, only the oscillating part 20a will be described.

[0011] The swinging part 20a includes an extension part 21, a bifurcated part 22, and an arm part 23. The extension part 21 extends linearly from the inside to the outside of the main body part 10 through an opening 13 formed in the main body part 10. The extension part 21 swings within a predetermined range upon receiving power from a motor M. The bifurcated part 22 extends in a T-shape from the tip of the extension part 21 in a direction perpendicular to the extension direction of the extension part 21. The arm part 23 extends from the left and right ends of the bifurcated part 22 in a direction substantially perpendicular to the extension direction of the extension part 21 and the extension direction of the bifurcated part 22. A hole 24 is formed at the tip of the arm part 23. The swinging part 20a swings within a predetermined range in an arc direction Ra around a predetermined position in the main body part 10. Similarly, the swinging part 20b swings within a predetermined range in an arc direction Rb around a predetermined position in the main body part 10. The swinging parts 20a and 20b swing so that the arm 23 of the swinging part 20a and the arm 23 of the swinging part 20b move toward and away from each other. Although details will be described later, the swinging parts 20a and 20b swinging in the arc directions Ra and Rb constitute a Scotch yoke mechanism via their respective arms 23 with respect to the gripping parts 50a and 50b supported by the slide mechanism 30 so as to be slidable in the slide direction D.

[0012] Fig. 3 is an external perspective view of the slide mechanism 30 and the gripping portions 50a and 50b. The slide mechanism 30 includes a rail 31, a fixed plate 35, and sliders 40a and 40b. Although not shown in Fig. 3, as shown in Fig. 1, the rail 31 is fixed to the tip 12 of the main body portion 10 via the fixed plate 35. The fixed plate 35 is a plate-shaped member. The rail 31 extends in the sliding direction D. The sliders 40a and 40b are supported on the rail 31 so as to be slidable in the sliding direction D.

[0013] The sliders 40a and 40b are fixed with the gripping parts 50a and 50b by a plurality of screws S1. The sliders 40a and 40b are the same member, so only the slider 40a will be described. The slider 40a is a plate having a predetermined thickness. The bottom surface of the slider 40a is slidably engaged with the rail 31. A recess 42 is formed on each of the two side surfaces of the slider 40a. A retaining tube 44 is loosely fitted in the recess 42. The retaining tube 44 is cylindrical. A shaft 46 is loosely fitted in the retaining tube 44. The tip of the shaft 46 fits into the hole 24 of the arm 23 of the swinging part 20a as shown in FIG. 1. As a result, the swinging part 20a swings in the arc direction Ra, causing the slider 40a and the gripping part 50a to slide in the sliding direction D. The same is true for the slider 40b and the gripping part 50b. Therefore, when the swinging portions 20a and 20b swing toward and away from each other, the slide mechanism 30 causes the gripping portions 50a and 50b to move linearly along the sliding direction D toward and away from each other.

[0014] 1, a stopper 32a is attached to one end of the rail 31, and a stopper 32b is attached to the other end of the rail 31. The slider 40a of the gripping part 50a abuts against the stopper 32a, thereby preventing the gripping part 50a from falling off the rail 31. Similarly, the slider 40b of the gripping part 50b abuts against the stopper 32b, thereby preventing the gripping part 50b from falling off the rail 31.

[0015] The gripping portion 50a has a base end surface 51 and a tip surface 52 that are spaced apart from each other in a direction parallel to the rotation axis B. The same applies to the gripping portion 50b. The tip surface 52 of the gripping portion 50a and the tip surface 52 of the gripping portion 50b face each other. The abutting portion 70a is provided on the tip surface 52 side of the gripping portion 50a. The abutting portion 70b and the gripping portion 50b are also similar. A leaf spring 90 is fixed to the tip surface 52 of the gripping portion 50a by a screw S2. The same applies to the gripping portion 50b. The leaf spring 90 will be described later. When the gripping device 1 grips an object to be gripped, the gripping portions 50a and 50b approach each other due to the swinging of the swinging portions 20a and 20b, and the gripping portions 50a and 50b grip the object to be gripped via the abutting portions 70a and 70b.

[0016] FIG. 4 is a cross-sectional perspective view of the gripping portion 50b. FIG. 5 is a cross-sectional view of the gripping portion 50a. The gripping portion 50a and the gripping portion 50b have the same structure and face each other so as to approach and move away from each other on the rail 31 in the sliding direction D. The following description is based on the assumption that the structure of the gripping portion 50a is the same as that of the gripping portion 50b. The gripping portion 50a has a storage portion H1, a communication hole H2, and a storage portion H3 formed therein. The storage portion H1, the communication hole H2, and the storage portion H3 are aligned along the rotation axis B. The storage portion H1 is formed on the base end surface 51 side. The storage portion H3 is formed on the tip end surface 52 side. The communication hole H2 is located between the storage portion H1 and the storage portion H3. The inner diameter of the communication hole H2 is smaller than the inner diameters of the storage portions H1 and H3. The inner diameter of the storage portion H1 and the inner diameter of the storage portion H3 are approximately the same. The communication hole H2 is defined by a protrusion 53 that protrudes radially inward between the receiving portions H1 and H3.

[0017] A radial bearing B1 is held in the housing H1. A radial bearing B2, a linear bushing B3, and a coil spring 56 are arranged in the housing H3. A shaft 54 ​​is held so as to pass through the housing H1, the communication hole H2, and the housing H3. A base end of the shaft 54 ​​is rotatably supported by the radial bearing B1. A tip end of the shaft 54 ​​is rotatably supported by the radial bearing B2. In this manner, the shaft 54 ​​is rotatably supported by the gripping portion 50a. As a result, the abutment portion 70a is rotatably supported with respect to the gripping portion 50a.

[0018] A screw S3 is fixed to the base end of the shaft 54. The outer diameter of the head of the screw S3 is larger than the inner diameter of the radial bearing B1. A contact portion 70a is fixed to the tip of the shaft 54 ​​by a screw S4. The outer diameter of the contact portion 70a is larger than the outer diameter of the radial bearing B2. This prevents the shaft 54 ​​from falling off the radial bearings B1 and B2.

[0019] The outer peripheral surface of the radial bearing B2 is in contact with the inner peripheral surface of the linear bush B3. The linear bush B3 holds the radial bearing B2 movably along the rotation axis B. The coil spring 56 is arranged in a compressed state between the protrusion 53 and the radial bearing B2. Therefore, the coil spring 56 biases the radial bearing B2 toward the abutment portion 70a. The shaft 54 ​​passes through the coil spring 56, so that the shaft 54 ​​and the coil spring 56 do not interfere with each other. As shown in FIG. 5, when the head of the screw S3 is in abutment with the radial bearing B1, the abutment portion 70a is spaced from the grip portion 50a via a predetermined gap. In this way, the biasing force of the coil spring 56 maintains the state in which the head of the screw S3 is in abutment with the radial bearing B1 and the abutment portion 70a is spaced from the grip portion 50a. The coil spring 56 is an example of a biasing portion.

[0020] Here, the contact portion 70a contacts the radial bearing B2. Therefore, when the contact portion 70a is pressed toward the grip portion 50a against the biasing force of the coil spring 56, the contact portion 70a moves toward the grip portion 50a together with the shaft 54 ​​and the radial bearing B2, and the head of the screw S3 moves away from the radial bearing B1. When the contact portion 70a is further pressed toward the grip portion 50a, the contact portion 70a contacts the grip portion 50a. This will be described in detail later.

[0021] FIG. 6 is an external perspective view of the abutting portion 70a. The abutting portion 70a has a base end surface 71 facing the tip surface 52 of the gripping portion 50a, and a tip surface 72 on the opposite side of the base end surface 71. In FIG. 1 and FIG. 3, the tip surface 72 of the abutting portion 70a and the tip surface 72 of the abutting portion 70b face each other. A hole h7 through which the screw S4 passes is formed in the center of the abutting portion 70a. A raised portion 73 is formed around the hole h7 of the base end surface 71. The outer diameter of the raised portion 73 is smaller than the outer diameter of the radial bearing B2. The raised portion 73 abuts against the radial bearing B2. A plurality of grooves 75 are formed radially outward of the raised portion 73 of the base end surface 71. The plurality of grooves 75 extend radially around the hole h7, in other words, around the rotation axis B of the abutting portion 70a.

[0022] 7 is an external perspective view of the grip portion 50a. A plurality of grooves 55 are formed on the tip surface 52 of the grip portion 50a around the edge of the storage portion H3. The plurality of grooves 55 extend radially from the storage portion H3 as the center. The grooves 55 and the grooves 75 are approximately the same in number and shape. The tip surface 52 is formed with a recess 59 to which a leaf spring 90 is fixed.

[0023] 8 is a partial enlarged view of FIG. 5. The base end surface 71 of the contact portion 70a is positioned in either the rotation allowable region (P1-P2) or the rotation restricted region (P2-P3) based on the positions indicated by the farthest position P1, the rotation restriction start position P2, and the maximum rotation restriction position P3. The farthest position P1 is the position where the contact portion 70a is farthest from the grip portion 50a. The maximum rotation restriction position P3 is the position where the contact portion 70a abuts against the grip portion 50a. The rotation restriction start position P2 is the position where the engagement between the multiple grooves 55 of the grip portion 50a and the multiple grooves 75 of the contact portion 70a starts. When the grip portions 50a and 50b are not gripping a gripping object, the contact portion 70a is positioned at the farthest position P1. The same is true for the contact portion 70b.

[0024] When the gripping portions 50a and 50b grip an object to be gripped with a strong gripping force, the contact portion 70a is positioned in the rotation restriction region (P2-P3) against the biasing force of the coil spring 56, and the grooves 55 and 75 engage with each other. This restricts the rotation of the contact portion 70a. The same applies to the contact portion 70b. Therefore, the object to be gripped is held in a constant posture.

[0025] When the gripping portions 50a and 50b grip the object to be gripped with a weak gripping force, the contact portion 70a is positioned in the rotation allowance region (P1-P2). This allows the contact portion 70a to rotate while gripping the object to be gripped. The same applies to the contact portion 70b. Therefore, the object to be gripped is held rotatably. For example, the object to be gripped may be rotated by the weight of the object to be gripped, for example, by gripping a position away from the center of gravity of the object with a weak gripping force and lifting it up. The object to be gripped may also be rotated by pressing a part of the object to the floor while gripping it with a weak force.

[0026] As described above, the simple mechanism switches between a state in which the object to be grasped is rotatably held and a state in which the object to be grasped is held in a fixed position. Therefore, the grasping device 1 avoids an increase in manufacturing costs and complicated control.

[0027] Here, the switching between the state in which the gripping object is held rotatably and the state in which the gripping object is held without rotating will be described in detail. The motor M is equipped with an encoder (not shown). This allows the rotation angle and rotation speed of the motor M to be accurately grasped. In addition, a control circuit (not shown) that drives the motor M has a function of detecting the current flowing through the coil of the motor M. This allows the output torque of the motor M to be estimated. In other words, the rotation position and output torque of the motor M can be set arbitrarily. By controlling the rotation of the motor M in such an environment, the swing of the swinging parts 20a and 20b to which the power of the motor M is transmitted by a mechanism such as gears can be controlled. As a result, it is possible to set "the position of the gripping parts 50a and 50b on the rail 31" and "the mutual gripping force of the gripping parts 50a and 50b obtained by converting the output torque into a linear force in the sliding direction D". The spring constants of the coil spring 56 biasing the contact portion 70a from the grip portion 50a and the coil spring 56 biasing the contact portion 70b from the grip portion 50b are known. Therefore, the contact portions 70a and 70b can be adjusted to provide any desired gripping force at any position between the farthest position P1 and the maximum rotation restriction position P3.

[0028] On the above premise, first, the object to be grasped is grasped with a gripping force strong enough to allow the contact parts 70a and 70b to reach the maximum rotation restriction position P3. This allows the object to be held without rotating. Next, when it is desired to hold the object to be grasped rotatably, the motor M is controlled to loosen the gripping force acting on the grip parts 50a and 50b from the state in which the object to be grasped is held without rotating. The contact parts 70a and 70b are positioned in the rotation allowable region (P1 to P2) by separating the grip parts 50a and 50b by a certain value. In the rotation allowable region (P1 to P2), the force of the coil spring 56 biasing the contact part 70a from the grip part 50a and the force of the coil spring 56 biasing the contact part 70b from the grip part 50b allow the object to be held rotatably.

[0029] In this way, switching is performed between "gripping with a gripping force strong enough that the contact parts 70a and 70b reach the maximum rotation restriction position P3" and "gripping using the force applied by the coil spring 56 by controlling the contact parts 70a and 70b to be located in the rotation allowance region (P1 to P2)". This makes it possible to freely switch between a state in which the object to be grasped can be held without rotating and a state in which the object to be grasped can be held rotatably.

[0030] As shown in FIG. 5, the base end of the leaf spring 90 is fixed to the recess 59 of the gripping portion 50a. The leaf spring 90 is bent in the middle. The tip of the leaf spring 90 abuts against and presses the base end surface 71 of the abutting portion 70a. As a result, when the abutting portion 70a rotates, the tip of the leaf spring 90 slides against the base end surface 71 of the abutting portion 70a. In this way, the leaf spring 90 applies a sliding resistance to the rotation of the abutting portion 70a. For example, when the gripping object is gripped with the abutting portion 70a positioned at the rotation restriction start position P2, the gripping object is prevented from rotating too much. In addition, the leaf spring 90 also abuts against the base end surface 71 of the abutting portion 70a located at the farthest position P1. As a result, the abutting portion 70a is prevented from rotating inadvertently at the farthest position P1. The leaf spring 90 is an example of a damping portion.

[0031] The pressing force applied by the leaf spring 90 to the contact portion 70a increases as the contact portion 70a approaches the maximum rotation restriction position P3. In other words, the sliding resistance applied by the leaf spring 90 to the contact portion 70a increases as the contact portion 70a approaches the maximum rotation restriction position P3. In this way, the ease of rotation of the grasped object is adjusted according to the gripping force.

[0032] The grooves 55 and 75 are examples of the engaging portion, but the engaging portion is not limited thereto. For example, a protrusion may be provided on the base end surface 71 of the abutting portion 70a at a position spaced a predetermined distance from the rotation center of the abutting portion 70a, and a plurality of recesses may be provided on the tip end surface 52 of the gripping portion 50a on a circumference spaced the same predetermined distance from the rotation center of the abutting portion 70a, which are capable of engaging with the protrusion. A protrusion may be provided on the tip end surface 52 of the gripping portion 50a at a position spaced a predetermined distance from the rotation center of the abutting portion 70a, and a plurality of recesses may be provided on the base end surface 71 of the abutting portion 70a on a circumference spaced the same predetermined distance from the rotation center of the abutting portion 70a, which are capable of engaging with the protrusion. In this case, the protrusion and the recess are examples of the engaging portion. In addition, external teeth may be provided on the outer periphery of the abutting portion 70a, and internal teeth that engage with the external teeth may be provided on the gripping portion 50a. In this case, the external teeth and the internal teeth are examples of the engaging portion.

[0033] Also, a sheet with high frictional force may be attached to at least one of the base end surface 71 of the abutting portion 70a and the tip end surface 52 of the gripping portion 50a, and the rotation of the abutting portion 70a relative to the gripping portion 50a may be restricted by the frictional force of the sheet. In this manner, the rotation of the abutting portion 70a may be restricted by a means other than the engagement portion.

[0034] In the above embodiment, it is assumed that the gripping portion 50a and the gripping portion 50b have the same structure, and both the gripping portions 50a and 50b have the groove 55, and both the contact portions 70a and 70b have the groove 75, but this is not limiting. For example, the gripping portion 50a and the contact portion 70a may have the grooves 55 and 75, respectively, and the gripping portion 50b and the contact portion 70b may not have such an engagement portion. This is because it is sufficient to restrict the rotation of either one of the contact portions 70a and 70b.

[0035] The tip of the leaf spring 90 is in sliding contact with the base end surface 71 of the contact portion 70a, but is not limited to this. For example, the tip of the leaf spring 90 may be in sliding contact with a part of the outer periphery of the contact portion 70a. In this case, the sliding resistance applied by the leaf spring 90 to the contact portion 70a is approximately constant regardless of the position of the contact portion 70a.

[0036] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0037] 1 Gripping device 10 Main body 20a, 20b Swinging portion 30 Slide mechanism 31 Rail 40a, 40b Slider 50a, 50b grip part 55, 75 Groove (engagement part) 56 Coil spring (biasing part) 70a, 70b Contact part 90 Leaf spring (braking part)

Claims

1. A main body portion, First and second gripping parts supported on the main body part so as to be movable toward and away from each other along a predetermined direction; a first abutment portion and a second abutment portion opposed to each other in the predetermined direction and supported by the first and second gripping portions, respectively, so as to be rotatable around the predetermined direction; the first contact portion is supported by the first grip portion so as to be movable between a rotation allowing position and a rotation restricting position, the rotation permitted position is a position in which the first abutment portion is separated from the first gripping portion and is permitted to rotate with respect to the first gripping portion, A gripping device, wherein the rotation restriction position is a position where the first abutment portion abuts against the first gripping portion, thereby restricting rotation relative to the first gripping portion.

2. the first gripping portion has a biasing portion that biases the first abutment portion to the rotation allowing position, The gripping device according to claim 1 , wherein the first contact portion moves from the rotation allowing position to the rotation restricting position against the biasing force of the biasing portion in response to a gripping force applied by the first and second gripping portions to grip the object to be gripped.

3. The gripping device according to claim 2 , wherein the first gripping portion and the first contact portion each have an engagement portion that engages with each other at the rotation restricting position.

4. The gripping device according to claim 3 , wherein the engagement portion is a plurality of grooves extending radially from a rotation center of the first contact portion.

5. The gripping device according to claim 1 , further comprising a braking portion supported by the first gripping portion and applying a sliding resistance to the rotation of the first contact portion.

6. The damping portion is a leaf spring, A base end of the leaf spring is fixed to the first gripping portion, The gripping device according to claim 5 , wherein a tip of the leaf spring abuts against the first abutment portion.

7. The gripping device according to claim 6 , wherein the sliding resistance applied by the leaf spring to the rotation of the first contact portion increases as the first contact portion approaches the rotation restriction position.

8. First and second swinging parts swingably supported on the main body part; a slide mechanism provided in the main body portion and supporting the first and second grip portions so as to be slidable in the predetermined direction; The gripping device according to claim 1 , wherein the first and second gripping parts are moved in the predetermined direction by the swinging of the first and second swinging parts, respectively.

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