Stopper structure of robot arm, and robot

Abstract

A stopper structure of a robot arm comprises a robot arm 12, and a base 11 rotatably supporting the robot arm 12 and abutting on the robot arm 12 to restrict rotation when the robot arm 12 rotates to an end of a rotation range, the robot arm 12 having a stopper 20 abutting on the base 11, the stopper 20 having an elastic member 31 which abuts on the base 11 when the robot arm 12 rotates to an end of the rotation range and which is compressed by the base 11 and a fixing part 30 provided to the robot arm 12, and a metallic member 35 fitted to the elastic member 31, and the metallic member 35 being provided at a position not in contact with the base 11.

Description

Stopper structure of robot arm and robot

[0001] The technology disclosed in this specification relates to a stopper structure for a robot arm and a robot.

[0002] 2. Description of the Related Art Conventionally, stopper structures that restrict the rotation of a robot arm have been known (see, for example, Patent Documents 1 and 2).

[0003] The swivel-arm robot described in Patent Document 1 includes a first member (arm support) and a second member (first arm portion) connected to the first member so as to be rotatable relative to the first member. The second member includes a member main body (arm main body) and a protrusion provided to protrude outward from a wall surface of the member main body. The protrusion restricts the rotation range of the second member by abutting against the first member as the second member rotates. The document also describes that the second member is made of die-cast aluminum alloy. The document also describes that the protrusion is formed integrally with the second member. Therefore, the protrusion described in the document is made of metal.

[0004] The stopper structure described in Patent Document 2 is a stopper structure that restricts rotation of an arm and a mechanical element (base) beyond a predetermined angle, and includes a protrusion formed on the arm, a hole formed in the mechanical element, and a stopper that is inserted into the hole so that a portion of it is exposed from the hole, and the stopper is composed of a block made of elastic resin and a surface metal plate with an angled cross-section that is arranged along the front side of the surface of the block that comes into contact with the protrusion.

[0005] Japanese Patent No. 7182013 Japanese Patent Application Laid-Open No. 2023-134948

[0006] In the swivel-arm robot described in Patent Document 1, a metal protrusion on the second member collides with the first member. Typically, the first member to which the second member is rotatably connected is also made of metal. Therefore, in the swivel-arm robot described in Patent Document 1, hard members collide with each other, potentially generating an impact upon collision. Therefore, there is room for improvement in terms of shock absorption. Furthermore, in the swivel-arm robot described in Patent Document 1, a hard protrusion collides with the hard first member, leaving room for improvement in terms of product protection.

[0007] The stopper structure described in Patent Document 2 includes a protrusion formed on an arm, a hole formed in a base (a mechanical element), a stopper inserted into the hole so that a portion of the stopper is exposed through the hole, and a retaining plate that prevents the stopper from falling out of the hole. The stopper is composed of a block made of elastic resin and a surface metal plate with an angled cross section. In the stopper structure described in Patent Document 2, the protrusion formed on the arm and the surface metal plate collide. Since the arm is typically made of metal, the protrusion formed on the arm is hard. The surface metal plate is also made of metal and is therefore hard. Therefore, the stopper structure described in Patent Document 2 involves collision between hard components, leaving room for improvement in terms of product protection. Furthermore, the stopper structure described in Patent Document 2 requires a certain amount of elastic resin to adequately absorb the collision load, leaving room for improvement in terms of reducing the size of the stopper structure.

[0008] An object of one aspect of the present invention is to improve the impact absorption capacity and product protection while suppressing an increase in the size of the stopper.

[0009] The stopper structure for a robot arm according to the present disclosure comprises a robot arm and a support part that rotatably supports the robot arm and abuts against the robot arm to restrict rotation when the robot arm rotates to the end of its rotation range, the robot arm having a stopper that abuts against the support part, the stopper abutting against the support part when the robot arm rotates to the end of its rotation range, the stopper having an elastic member that abuts against the support part and a fixed part provided on the robot arm, and a metal member that is fitted into the elastic member, the metal member being positioned so as not to come into contact with the support part.

[0010] According to the above configuration, it is possible to improve the shock absorption capacity and product protection while suppressing an increase in the size of the stopper.

[0011] Schematic diagram of a picking robot according to the first embodiment; Top view of the base; Perspective view of the picking robot as seen from below; Partial cross-sectional view showing a state in which the stopper abuts against a rotation restricting portion; Exploded perspective view of the stopper; Bottom view of the stopper; Exploded perspective view of the stopper; Schematic diagram for explaining the action of the stopper; Schematic diagram for explaining the action of the stopper according to a comparative example; Bottom view of the stopper according to the second embodiment; Bottom view of the stopper according to the third embodiment; Exploded perspective view of the stopper according to the fourth embodiment; Cross-sectional view of the stopper; Exploded perspective view of the stopper according to the fifth embodiment; Cross-sectional view of the stopper; Top view showing a state in which the stopper according to the sixth embodiment abuts against a robot arm; Top view showing a state in which the stopper according to the seventh embodiment abuts against a robot arm; Perspective view of the rotation restricting portion

[0012] [Outline of the Present Embodiment] First, an outline of the present embodiment will be listed and described.

[0013] (1) A stopper structure for a robot arm according to the present disclosure comprises a robot arm and a support part that rotatably supports the robot arm and abuts against the robot arm to restrict rotation when the robot arm rotates to the end of its rotation range, the robot arm having a stopper that abuts against the support part, the stopper abutting against the support part when the robot arm rotates to the end of its rotation range, the stopper having an elastic member that abuts against the support part and a fixed part provided on the robot arm, and that is compressed by the support part, and a metal member that is fitted into the elastic member, the metal member being positioned so as not to come into contact with the support part.

[0014] According to the stopper structure described in (1) above, the elastic member abuts the support portion, which makes it easier to absorb impact compared to when a metal member abuts the support portion. Furthermore, because the elastic member abuts the support portion, the support portion is less likely to be damaged compared to when a metal member abuts the support portion. This improves impact absorption and product protection. However, if impact is absorbed solely by the elastic member, the elastic member must be large to absorb the impact sufficiently. According to the stopper structure described in (1) above, the metal member is fitted into the elastic member, so impact is absorbed not only by the elastic member but also by the metal member. This allows the size of the elastic member to be smaller than when impact is absorbed solely by the elastic member. This prevents the stopper from becoming larger. Because the metal member is positioned so as not to contact the support portion, damage to the support portion by the metal member is also prevented. Therefore, the stopper structure described in (1) above improves impact absorption and product protection while preventing the stopper from becoming larger.

[0015] (2) A stopper structure for a robot arm as described in (1) above, wherein the metal member is inserted into a fitting hole formed in the elastic member, and the fitting hole is provided at a position between the fixed part and the support part when the robot arm is rotated to the end of its rotation range, and the metal member is elastically deformed by a collision load from the support part when the robot arm is rotated to the end of its rotation range.

[0016] According to the stopper structure described in (2) above, when the robot arm rotates to the end of its rotation range and the stopper collides with the support portion, the portion of the elastic member between the metal member and the support portion is compressed by the collision load. This absorbs the impact. The metal member is then pressed by the compressed elastic member and elastically deforms. This absorbs the impact. The portion of the elastic member between the metal member and the fixed portion is then pressed by the elastically deformed metal member and compressed. This absorbs the impact. In this way, according to the stopper structure described in (2) above, the impact is absorbed not only by the elastic member but also by the metal member, so the size of the elastic member can be made smaller than when impact is absorbed only by the elastic member.

[0017] (3) In the stopper structure of the robot arm described in (2) above, the metal member may be plastically deformed when a collision load of a predetermined value or more is applied from the support portion via the elastic member when the stopper collides with the support portion.

[0018] The above-mentioned predetermined value is assumed to be greater than the maximum collision load that occurs when the robot arm is operating normally. Therefore, when the robot arm is operating normally, the metal member returns to its original shape through elastic deformation. However, it is possible that a collision load greater than the predetermined value may be applied for some unexpected reason. According to the stopper structure described in (3) above, even if a collision load greater than the predetermined value is applied, the metal member undergoes plastic deformation, thereby absorbing the impact on the robot arm. However, a plastically deformed metal member cannot continue to be used as is, and therefore must be repaired or replaced.

[0019] (4) In a stopper structure for a robot arm described in any one of (1) to (3) above, the metal member may be fitted to the elastic member from the outside, and may prevent the elastic member from deforming in a direction away from the fixed portion when the stopper collides with the support portion.

[0020] When the stopper collides with the support portion, the elastic member may deform in a direction away from the fixed portion. If the elastic member deforms in a direction away from the fixed portion, the deformed portion no longer contributes to absorbing the impact, resulting in a decrease in impact absorption capacity. According to the stopper structure described in (4) above, the deformation of the elastic member in a direction away from the fixed portion is restricted by the metal member fitted to the elastic member from the outside. Therefore, it is possible to prevent the elastic member from deforming in a direction away from the fixed portion and thereby reducing impact absorption capacity.

[0021] (5) A stopper structure for a robot arm according to the present disclosure comprises a robot arm, a support portion for rotatably supporting the robot arm, and a rotation restriction portion for contacting the robot arm to restrict rotation when the robot arm rotates to the end of its rotation range, wherein the robot arm has a stopper that contacts the rotation restriction portion, and the stopper contacts the rotation restriction portion when the robot arm rotates to the end of its rotation range, and comprises an elastic member that is compressed by a fixed portion provided on the robot arm and the rotation restriction portion, and a metal member that is fitted into the elastic member, and the metal member is positioned so as not to come into contact with the rotation restriction portion.

[0022] According to the stopper structure described in (5) above, it is possible to improve the impact absorption capacity and product protection while suppressing an increase in the size of the stopper. The rotation restricting portion may be provided integrally with the support portion, or may be provided separately from the support portion.

[0023] (6) A stopper structure for a robot arm according to the present disclosure is a stopper structure for a robot arm, comprising: a robot arm; and a support part that rotatably supports the robot arm, wherein the support part has a stopper that abuts against the robot arm to restrict rotation when the robot arm rotates to the end of its rotation range, the stopper abuts against the robot arm when the robot arm rotates to the end of its rotation range, and comprises: an elastic member that abuts against the robot arm when the robot arm rotates to the end of its rotation range, and is compressed by a fixing part provided on the support part and the robot arm; and a metal member that fits into the elastic member, wherein the metal member is positioned so as not to come into contact with the robot arm.

[0024] According to the stopper structure described in (6) above, it is possible to improve the shock absorption capacity and product protection while suppressing an increase in the size of the stopper.

[0025] (7) A stopper structure for a robot arm according to the present disclosure includes a robot arm, a support portion that rotatably supports the robot arm, and a rotation restriction portion that abuts against the robot arm when the robot arm rotates to the end of its rotation range to restrict rotation, the rotation restriction portion having a stopper that abuts against the robot arm, the stopper abutting against the robot arm when the robot arm rotates to the end of its rotation range, and having an elastic member that is compressed by a fixing portion provided on the rotation restriction portion and the robot arm, and a metal member that is fitted into the elastic member, and the metal member is positioned so as not to come into contact with the robot arm.

[0026] According to the stopper structure described in (7) above, it is possible to improve the impact absorption capacity and product protection while suppressing an increase in the size of the stopper. The rotation restricting portion may be provided integrally with the support portion, or may be provided separately from the support portion.

[0027] (8) A robot according to the present disclosure includes the stopper structure for a robot arm described in any one of (1) to (7) above.

[0028] According to the robot described in (8) above, it is possible to improve the impact absorption capacity and product protection while suppressing an increase in the size of the stopper.

[0029] [Details of the Embodiments of the Present Disclosure] Details of the embodiments of the present disclosure are described below. The present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. The embodiments of the present disclosure can be realized in various forms, such as an apparatus, a system, a method, a computer program for implementing the functions of these apparatus, systems, or methods, and a recording medium on which the computer program is recorded.

[0030] First Embodiment A first embodiment will be described with reference to Figures 1 to 9. In the following description, the reference numerals of the drawings may be omitted for the same components, with some exceptions.

[0031] (1) Picking Robot A picking robot 1 according to a first embodiment will be described with reference to Fig. 1 . The picking robot 1 is a horizontal articulated SCARA robot. The picking robot 1 performs tasks such as grasping (picking) parts such as bolts and nuts contained in containers and transferring them to trays. A controller (not shown) is connected to the picking robot 1. The controller is connected to a control device (not shown) such as a personal computer, and outputs control signals to the picking robot 1 according to instructions from the control device.

[0032] The picking robot 1 includes a base 11 (an example of a support portion), a robot arm 12, a work head 13, and a hand portion (not shown). The robot arm 12 and the base 11 form a stopper structure of the robot arm according to embodiment 1. The housing of the base 11 and the housings of the robot arm 12 and work head 13 are made of metal members such as aluminum alloy, and are manufactured by die casting, sand casting, or the like.

[0033] The base 11 is fixed to a workbench or the like in a factory. A first motor (not shown) that rotates the robot arm 12 is housed inside the base 11. The first motor may be provided on the robot arm 12. The robot arm 12 is disposed on the base 11. One end of the robot arm 12 in the longitudinal direction as viewed from above is rotatably supported by the base 11, and rotates around a vertical line.

[0034] The working head 13 is disposed on the robot arm 12. When viewed from above, one end of the working head 13 in the longitudinal direction is rotatably supported on the other end of the robot arm 12, and the working head 13 rotates around a vertical line. A second motor (not shown) that rotates the working head 13 is housed inside the working head 13. The second motor may be provided on the robot arm 12.

[0035] The work head 13 has a shaft 13A that extends in the vertical direction. The shaft 13A is provided at the other end of the work head 13 in the longitudinal direction when viewed from above. The shaft 13A is movable in the vertical direction and is rotatable around its central axis. The work head 13 houses a third motor (not shown) that moves the shaft 13A in the vertical direction, and a fourth motor (not shown) that rotates the shaft 13A.

[0036] A hand unit (not shown) is detachably attached to the lower end of the shaft 13A. The hand unit has, for example, a pair of claws extending downward. A part is gripped when the pair of claws approach each other, and the part is released when the pair of claws move away from each other. The hand unit is provided with a fifth motor for displacing the pair of claws, and a conversion mechanism for converting the rotation of the fifth motor into the displacement of the pair of claws. The structure of the hand unit is not limited to this and can be determined as appropriate.

[0037] (1-1) Base The base 11 has a base main body 15 that rotatably supports the robot arm 12, and an abutment portion 16 that abuts against the robot arm 12 when the robot arm 12 rotates to the end of its rotation range, thereby restricting its rotation. The base main body 15 has a main body portion 15A that is roughly circular when viewed from above, and an overhanging portion 15B that overhangs from the side of the main body portion 15A. One end of a bellows-shaped hose 22 is attached to the top surface of the overhanging portion 15B. The other end of the hose 22 is connected to the work head 13. Power lines and signal lines run through the hose 22. The abutment portion 16 is integrally formed on the top surface of the base main body 15.

[0038] 2, the contact portion 16 is roughly shaped as an integrated unit of a large circular portion 17 that protrudes upward from the top surface of the main body portion 15A and a small circular portion 18 that protrudes upward from the top surface of the protruding portion 15B, and the side surfaces of the circular portions 17 and 18 are connected via a concave curved surface 19. The concave curved surface 19 is the surface with which a stopper 20 of the robot arm 12 comes into contact.

[0039] (1-2) Stopper Structure of Robot Arm As shown in Fig. 3, a stopper 20 that abuts against the abutment portion 16 of the base 11 is provided on the underside of the end of the robot arm 12 on the base 11 side. As shown in Fig. 4, when the robot arm 12 rotates to one end and the other end of its rotation range, the stopper 20 abuts against the abutment portion 16, restricting further rotation.

[0040] As shown in Figure 5, a fixing portion 30 is provided on the underside of the robot arm 12. The fixing portion 30 is formed integrally with the robot arm 12 and protrudes downward from the underside of the robot arm 12. The fixing portion 30 is made of a metal member and has high rigidity. The fixing portion 30 does not necessarily have to be formed integrally with the robot arm 12 as long as it is fixed to the robot arm 12.

[0041] The stopper 20 has an elastic member 31 and a sheet metal member 35 (an example of a metal member) fitted into the elastic member 31. While methods for manufacturing metal members include die casting and sand casting, these methods take time and increase manufacturing costs. In the stopper structure according to the first embodiment, the metal member is the sheet metal member 35, which can be manufactured in a short time. This reduces manufacturing costs.

[0042] 6 , the fixing portion 30 has a rectangular shape having a first side 40, a second side 41, a third side 42, and a fourth side 43 when viewed from below. The shape of the fixing portion 30 is not limited to a rectangular shape and may be other shapes. The first side 40 extends in a direction substantially perpendicular to the direction in which a collision load 80 from the contact portion 16 (in other words, a reaction force from the contact portion 16, see FIG. 8 ) acts when the robot arm 12 rotates to one end of its rotation range.

[0043] One end of the second side 41 is continuous with one end of the first side 40. The second side 41 extends in a direction substantially perpendicular to the direction in which the collision load 80 received from the contact portion 16 acts when the robot arm 12 rotates to the other end of the rotation range.

[0044] The elastic member 31 contacts the contact portion 16 when the robot arm 12 rotates to the end of its rotation range and is compressed by the contact portion 16 and the fixed portion 30 provided on the robot arm 12. The elastic member 31 according to the first embodiment is fitted to the fixed portion 30 from the outside and fixed to the robot arm 12 with bolts 60. The elastic member 31 is made of urethane and has a roughly rectangular shape that is larger than the fixed portion 30. The shape of the elastic member 31 is not limited to a rectangular shape and may be other shapes. The material of the elastic member 31 is not limited to urethane and may be other materials as long as it is capable of absorbing shock. For example, the elastic member 31 may be synthetic rubber. When viewed from below, the elastic member 31 has a fifth side 51, a sixth side 52, a seventh side 53, and an eighth side 54. The fifth side 51 and the sixth side 52 are gently curved to correspond to the concave curved surface 19 of the contact portion 16.

[0045] The elastic member 31 has a first fitting hole 32 that fits into the fixed part 30 from the outside. The inner peripheral shape of the first fitting hole 32 roughly matches the outer peripheral shape of the fixed part 30. The elastic member 31 does not necessarily have to fit into the fixed part 30, as long as it is compressed by the fixed part 30 and the abutment part 16 when the robot arm 12 rotates to the end of its rotation range.

[0046] In the elastic member 31, a bolt insertion hole 33 is formed between the third side 42 of the fixing portion 30 and the seventh side 53 of the elastic member 31, into which a bolt 60 is inserted for fixing the stopper 20 to the robot arm 12. Similarly, in the elastic member 31, a bolt insertion hole 33 is formed between the fourth side 43 of the fixing portion 30 and the eighth side 54 of the elastic member 31, into which a bolt 60 is inserted.

[0047] In the elastic member 31, an elongated second fitting hole 34A is formed between the first side 40 of the fixing portion 30 and the fifth side 51 of the elastic member 31, into which a first extending piece 62A of the sheet metal member 35 (described later) is fitted and inserted. The second fitting hole 34A is generally parallel to the first side 40. Similarly, in the elastic member 31, an elongated second fitting hole 34B is formed between the second side 41 of the fixing portion 30 and the sixth side 52 of the elastic member 31, into which a first extending piece 62B of the sheet metal member 35 (described later) is fitted and inserted. The second fitting hole 34B is generally parallel to the second side 41.

[0048] The sheet metal member 35 will be described with reference to Figure 7. The sheet metal member 35 is a member that cooperates with the elastic member 31 to absorb the collision load 80 from the contact portion 16. The sheet metal member 35 is provided in a position where it does not come into contact with the contact portion 16. The sheet metal member 35 has a flat plate portion 61, two elastically deformable first extension pieces 62 (62A, 62B), and two elastically deformable second extension pieces 63 (63A, 63B).

[0049] The outer peripheral shape of the flat plate portion 61 is a rectangle having a ninth side 71, a tenth side 72, an eleventh side 73, and a twelfth side 74 when viewed from above. The shape of the flat plate portion 61 is not limited to a rectangle and may be other shapes. The ninth side 71 extends between the first side 40 of the fixed portion 30 and the fifth side 51 of the elastic member 31, approximately parallel to the first side 40. The tenth side 72 extends between the second side 41 of the fixed portion 30 and the sixth side 52 of the elastic member 31, approximately parallel to the second side 41.

[0050] The first extending piece 62A extends from the outer edge that constitutes the ninth side 71 of the flat plate portion 61 and bends downward. That is, the first extending piece 62A extends from the outer edge of the flat plate portion 61 in a direction that intersects with the plate surface of the flat plate portion 61 (here, downward). When the robot arm 12 rotates to one end of its rotation range, the plate surface of the first extending piece 62A is approximately perpendicular to the direction in which the collision load 80 from the abutment portion 16 acts. This means that part of the collision load 80 is borne by the plate surface of the first extending piece 62A.

[0051] The first extension piece 62B extends from the outer edge portion constituting the tenth side 72 of the flat plate portion 61 and bends downward. The first extension piece 62B is inserted and fitted into the second fitting hole 34B of the elastic member 31. When the robot arm 12 rotates to the other end of the rotation range, the plate surface of the first extension piece 62B is approximately perpendicular to the direction in which the collision load 80 from the abutment portion 16 acts.

[0052] The second extending piece 63A extends and bends downward from the outer edge that forms the eleventh side 73 of the flat plate portion 61. The second extending piece 63B extends and bends downward from the outer edge that forms the twelfth side 74 of the flat plate portion 61. The elastic member 31 fits inside the two second extending pieces 63.

[0053] An insertion hole 64 into which the fixing part 30 is inserted is formed near the center of the flat plate part 61. When viewed from above, the shape of the insertion hole 64 is generally the same as the shape of the fixing part 30, but is slightly larger than the fixing part 30. Two recesses 65 are formed on the inner edge of the flat plate part 61 that constitutes the insertion hole 64 so as to avoid the bolt 60.

[0054] (2) Action of the Stopper The action of the stopper 20 when it collides with the contact portion 16 will be described with reference to Figures 8A and 8B. The action when the stopper 20 collides with the contact portion 16 differs depending on whether the collision load 80 is within a predetermined value or exceeds the predetermined value. The predetermined value is a value that is greater than the maximum value of the collision load 80 that occurs when the robot arm 12 is operating normally. Each case will be described below.

[0055] (2-1) When the Collision Load is Within a Predetermined Value The thickness and material of the first extension piece 62A are set so that it elastically deforms upon collision when the collision load 80 is within a predetermined value. The same applies to the first extension piece 62B. When the robot arm 12 rotates to one end of its rotation range and the stopper 20 collides with the abutment portion 16, the collision load 80 acts on the stopper 20 from the abutment portion 16. As described above, the first extension piece 62A is located between the fixed portion 30 and the abutment portion 16 when the robot arm 12 rotates to one end of its rotation range. Therefore, when the stopper 20 collides with the abutment portion 16, the portion of the elastic member 31 between the first extension piece 62A and the abutment portion 16 is compressed by the collision load 80, thereby absorbing the impact.

[0056] As described above, when the robot arm 12 rotates to the end of its rotation range, the plate surface of the first extension piece 62A is roughly perpendicular to the direction in which the collision load 80 from the abutment portion 16 acts, so that the first extension piece 62A is pushed by the compressed elastic member 31 and elastically deformed toward the fixed portion 30. This absorbs the impact. In Figure 8, force 81A (81) indicates the force with which the compressed elastic member 31 presses the first extension piece 62A.

[0057] Then, the portion of the elastic member 31 between the first extension piece 62A and the fixed portion 30 is pressed and compressed by the elastically deformed first extension piece 62A, thereby absorbing the impact. In FIG. 8 , force 81B indicates the force with which the first extension piece 62A compresses the elastic member 31. Force 81C indicates the force with which the compressed elastic member 31 presses the fixed portion 30. Since the fixed portion 30 does not elastically deform, force 81C is received by the fixed portion 30. However, because the collision load 80 is absorbed by the elastic member 31 and the first extension piece 62A, a force that would damage the robot arm 12 or the base 11 is not transmitted.

[0058] Part of the collision load 80 also acts as a force 82 in a direction that moves the elastic member 31 away from the fixed portion 30. This force 82 causes the elastic member 31 to deform in a direction that moves it away from the fixed portion 30, but the deformation is restricted by the second extending piece 63B of the sheet metal member 35. At this time, the elastic member 31 is compressed by a reaction force 83 from the second extending piece 63B, thereby absorbing the impact.

[0059] (2-2) When the Collision Load is Greater than a Predetermined Value It is possible that a collision load 80 greater than a predetermined value may be applied for some unexpected reason. The thickness and material of the first extension piece 62 (62A, 62B) are set so that when a collision load 80 greater than a predetermined value is applied, the first extension piece 62 undergoes plastic deformation and does not return to its original position. Because the first extension piece 62 undergoes plastic deformation, a force sufficient to damage the robot arm 12 or the base 11 is not transmitted even when a collision load 80 greater than a predetermined value is applied. However, because the first extension piece 62 does not return to its original position, the sheet metal member 35 cannot continue to be used as is. This requires replacement or repair of the sheet metal member 35.

[0060] (3) Effects of the Embodiment According to the stopper structure of the first embodiment, the elastic member 31 abuts against the base 11 (more specifically, the abutment portion 16 of the base 11), and therefore shock is more easily absorbed than when a hard member abuts against the abutment portion 16. Furthermore, because the elastic member 31 abuts against the abutment portion 16, the abutment portion 16 is less likely to be damaged than when a hard member abuts against it. This improves shock absorption and product protection.

[0061] However, if impact is absorbed solely by the elastic member 31, the elastic member 31 must be large to adequately absorb the impact. According to the stopper structure of embodiment 1, the sheet metal member 35 is fitted to the elastic member 31, so impact is absorbed not only by the elastic member 31 but also by the sheet metal member 35. The effect of the sheet metal member 35 will be explained by comparing it with a comparative example shown in FIGS. 9A and 9B . The stopper 820 of the comparative example does not include the sheet metal member 35 of embodiment 1. The stopper 820 of the comparative example also has the elastic member 831 abutting the abutment portion 16, which improves impact absorption and product protection compared to the prior art where hard members collide with each other. However, the elastic member 831 must be large to adequately absorb the impact. In contrast, according to the stopper 20 of embodiment 1, impact is absorbed not only by the elastic member 31 but also by the sheet metal member 35, so the size of the elastic member 31 can be made smaller than that of the stopper 820 of the comparative example. This prevents the stopper 20 from becoming larger in size. Because the sheet metal member 35 is positioned so as not to come into contact with the abutment portion 16, damage to the abutment portion 16 by the sheet metal member 35 is also prevented. Therefore, the stopper structure according to the first embodiment can improve impact absorption and product protection while preventing the stopper 20 from becoming larger in size. The stopper structure described in the aforementioned Patent Document 2 requires a retaining plate. In contrast, the stopper structure according to the first embodiment does not require a retaining plate, thereby reducing the number of parts. Furthermore, the stopper structure described in the same document requires a hole in the arm or mechanical element into which the stopper is inserted, making it difficult to retrofit the stopper structure to an existing product that does not have a hole. In contrast, the stopper structure according to the first embodiment does not require a hole into which the stopper is inserted, making it easier to retrofit the stopper structure to an existing product than the stopper structure described in the same document.

[0062] According to the stopper structure of embodiment 1, the impact is absorbed not only by the elastic member 31 but also by the first extension piece 62 (62A, 62B), so the size of the elastic member 31 can be made smaller than when the impact is absorbed only by the elastic member 31.

[0063] According to the stopper structure of embodiment 1, even if a collision load 80 greater than a predetermined value is applied, the first extension piece 62 undergoes plastic deformation, thereby absorbing the impact applied to the robot arm 12 and the base 11.

[0064] According to the stopper structure of the first embodiment, the second extending pieces 63 (63A and 63B) are fitted to the elastic member 31 from the outside (in other words, the elastic member 31 is fitted to the inside of the two second extending pieces 63), so the second extending pieces 63 restrict deformation of the elastic member 31 in a direction away from the fixed portion 30. Therefore, it is possible to prevent the elastic member 31 from deforming in a direction away from the fixed portion 30 and thereby reducing the shock absorbing capacity.

[0065] The effect of restricting deformation by the second extension piece 63 will be explained more specifically by comparing it with a comparative example shown in Figures 9A and 9B. In the stopper 820 according to the comparative example, the collision load 80 escapes so as to surround the fixed portion 30, and acts as a force 882 (882A, 882B) in a direction that moves the elastic member 831 away from the fixed portion 30. As a result, the elastic member 831 deforms before it is fully compressed, and it is unable to fully absorb the collision load 80. In contrast, in the stopper structure according to the first embodiment, the deformation of the elastic member 31 is restricted by the second extension piece 63, so that it is possible to prevent the elastic member 31 from deforming and reducing its impact absorption capacity.

[0066] According to the picking robot 1 of the first embodiment, it is possible to improve the shock absorption capacity and product protection while preventing the size of the stopper 20 from increasing.

[0067] <Embodiment 2> Embodiment 2 will be described with reference to Figure 10. A stopper 220 according to embodiment 2 includes an elastic member 222 that fits from the outside into a fixed portion 221, and a sheet metal member 223. The fixed portion 221 is generally diamond-shaped when viewed from below. The fixed portion 221 is provided integrally with the robot arm 12. The sheet metal member 223 has three first extension pieces 224 (224A, 224B, 224C) that fit into and are inserted into the elastic member 222.

[0068] The first extending pieces 224A and 224B are substantially the same as the first extending pieces 62A and 62B of the first embodiment. The first extending piece 224C is disposed closer to the fixed portion 221 than the first extending pieces 224A and 224B. The first extending piece 224C has a portion 225A that is substantially parallel to the first extending piece 224A and a portion 225B that is substantially parallel to the first extending piece 224B. The portion 225A is continuous with the portion 225B. The portions 225A and 225B do not have to be continuous.

[0069] According to the stopper structure of the second embodiment, it is possible to improve the shock absorption capacity and product protection while suppressing the increase in the size of the stopper 220 .

[0070] <Embodiment 3> Embodiment 3 will be described with reference to Figure 11. Figure 11 is a bottom view of a stopper 320 according to embodiment 3, with the front side facing the base 11. Figure 11 shows a cross section of the stopper 320 on the right side of the center in the left-right direction. The stopper 320 includes an elastic member 331 and a sheet metal member 335. The fixing part 330 includes a rectangular part 330A that is long in the left-right direction, and a protruding part 330B that protrudes in a triangular shape toward the front from the front edge of the rectangular part 330A (the edge on the base 11 side). The fixing part 330 is provided integrally with the robot arm 12.

[0071] The elastic member 331 is disposed on the front side of the fixed part 330 and is formed in a triangular shape that is convex toward the front. A triangular recess 331A is formed at the rear edge of the elastic member 331, into which the triangular protruding part 330B of the fixed part 330 fits. The elastic member 331 is formed with second fitting holes 334A and 334B that are elongated holes similar to the second fitting holes 34A and 34B of the first embodiment.

[0072] The sheet metal member 335 according to the third embodiment also has a flat plate portion (not shown) and first extension pieces 362 (362A and 362B), similar to the sheet metal member 35 according to the first embodiment. The first extension piece 362A is fitted and inserted into the second fitting hole 334A, and the first extension piece 362B is fitted and inserted into the second fitting hole 334B.

[0073] The sheet metal member 335 does not have extending pieces corresponding to the second extending pieces 63A and 63B of embodiment 1. The reason for this is that, as shown in Fig. 11 , the width in the left-right direction of the fixing portion 330 is approximately the same as the width in the left-right direction of the elastic member 331, and therefore rearward deformation of the elastic member 331 (i.e., deformation in the direction away from the fixing portion 330) is restricted by the fixing portion 330.

[0074] Two bolt insertion holes 333 are formed in the elastic member 331, into which bolts 360 are inserted laterally (horizontally). Through holes, into which the bolts 360 pass, are formed in the first extension pieces 362A and 362B. A screw hole, into which the bolts 360 are screwed, is formed in the triangular protruding portion 330B of the fixing part 330. The elastic member 331 is fixed to the fixing part 330 by the bolts 360 inserted into the bolt insertion holes 333.

[0075] According to the stopper structure of the third embodiment, it is possible to improve the shock absorption capacity and product protection while suppressing the increase in the size of the stopper 320 .

[0076] <Fourth Embodiment> A fourth embodiment will be described with reference to Figures 12 and 13. As shown in Figure 12, a stopper 420 according to the fourth embodiment has a cylindrical elastic member 431 and a metal member 435 roughly shaped like a half cylinder. A step portion 435A projecting outward from the lower end of the outer circumferential surface and a step portion 435B projecting inward from the lower end of the inner circumferential surface are integrally formed with the metal member 435. The fixing portion 430 is cylindrical and is provided integrally with the robot arm 12.

[0077] 13, the elastic member 431 is formed with a fitting hole 431A into which the metal member 435 is fitted and inserted, and a fitting hole 431B into which the fixed portion 430 is fitted and inserted. The fitting hole 431A passes through the elastic member 431 in the vertical direction. The fitting hole 431A does not have to pass through the elastic member 431 in the vertical direction. The elastic member 431 is fixed to the fixed portion 430 by a bolt 60 in a state in which the metal member 435 and the fixed portion 430 are fitted and inserted.

[0078] The formation of the inner step 435B ensures a gap between the fixed portion 430 and a portion 435C of the metal member 435 above the inner step 435B, allowing the upper portion 435C to deform toward the fixed portion 430. A part of the elastic member 431 is disposed between the inner step 435B and the fixed portion 430.

[0079] When the robot arm 12 rotates to the end of its rotation range and a collision load is applied, the metal member 435 moves toward the fixed part 430 while compressing the elastic member 431 located between the inner step 435B and the fixed part 430, and when the elastic member 431 located between them is compressed to a certain extent, further movement is restricted by the fixed part 430. When the movement of the metal member 435 is restricted, the collision load acts as a force that deforms the upper part 435C of the metal member 435 toward the fixed part 430. At this time, if the collision load is within a predetermined value, the upper part 435C is elastically deformed, and if the collision load is greater than the predetermined value, it is plastically deformed.

[0080] According to the stopper structure of the fourth embodiment, it is possible to improve the shock absorption capacity and product protection while suppressing the increase in size of the stopper 420 .

[0081] Fifth Embodiment A fifth embodiment will be described with reference to Figures 14 and 15. As shown in Figure 14, a stopper 520 according to the fifth embodiment has a cylindrical elastic member 531 and an annular metal member 535.

[0082] As shown in FIG. 15 , the elastic member 531 is formed with an annular fitting hole 531A into which the metal member 535 is fitted and inserted, and a fitting hole 531B into which the fixed portion 530 is fitted and inserted. The fitting hole 531A does not penetrate the elastic member 531 in the vertical direction. The fitting hole 531A may penetrate the elastic member 531 in the vertical direction. The metal member 535 is formed with a U-shaped cross section having an outer wall portion 535A and an inner wall portion 535B, and a space is secured between the outer wall portion 535A and the inner wall portion 535B. A portion of the elastic member 531 is disposed between the inner wall portion 535B and the fixed portion 530.

[0083] When the robot arm 12 rotates to the end of its rotation range and a collision load is applied, the metal member 535 moves toward the fixed portion 530 while compressing the elastic member 531 located between the inner wall portion 535B and the fixed portion 530. When the elastic member 531 located between the metal member 535 and the fixed portion 530 is compressed to a certain extent, further movement is restricted by the fixed portion 530. When the movement of the metal member 535 is restricted, the collision load acts as a force that deforms the outer wall portion 535A of the metal member 535 toward the fixed portion 530. At this time, if the collision load is within a predetermined value, the outer wall portion 535A is elastically deformed, and if the collision load is greater than the predetermined value, the outer wall portion 535A is plastically deformed. In other respects, the fifth embodiment is substantially the same as the fourth embodiment.

[0084] According to the stopper structure of the fifth embodiment, it is possible to improve the shock absorption capacity and product protection while suppressing the increase in size of the stopper 520 .

[0085] Sixth Embodiment A sixth embodiment will be described with reference to Fig. 16. As shown in Fig. 16, a stopper 620 according to the sixth embodiment is provided on the base 11 (an example of a support portion) rather than on the robot arm 12. Two stoppers 620 are provided in the sixth embodiment. One stopper 620 abuts against the robot arm 12 when the robot arm 12 rotates to one end of its rotation range to restrict further rotation, and the other stopper 620 abuts against the robot arm 12 when the robot arm 12 rotates to the other end to restrict further rotation.

[0086] The stopper 620 includes an elastic member 631 and a sheet metal member 635 (an example of a metal member) fitted into the elastic member 631. The elastic member 631 comes into contact with the robot arm 12 when the robot arm 12 rotates to the end of its rotation range, and is compressed by the robot arm 12 and a fixing portion 630 provided on the protruding portion 15B of the base main body 15. The sheet metal member 635 is provided in a position where it does not come into contact with the robot arm 12.

[0087] The hypotenuse of the fixing portion 630 extends in a direction substantially perpendicular to the direction in which the collision load from the robot arm 12 acts. The shape of the fixing portion 630 is not limited to a right triangle, and can be determined appropriately.

[0088] The elastic member 631 is generally trapezoidal when viewed from above, and has a surface that abuts against the fixed part 630 and a surface that abuts against the side surface of the robot arm 12. A fitting hole 634 into which the first extending piece 662 of the sheet metal member 635 is fitted and inserted is formed in the elastic member 631. The fitting hole 634 extends approximately parallel to the inclined surface of the fixed part 630.

[0089] The sheet metal member 635 has a flat plate portion (not shown) disposed below the elastic member 631 (toward the rear of the drawing in FIG. 16 ), a first extending piece 662 extending upward from the flat plate portion, and a second extending piece 663 extending upward from the flat plate portion and fitting into the elastic member 631 from the outside. As described above, the first extending piece 662 is fitted into the fitting hole 634 of the elastic member 631. The second extending piece 663 is disposed so as to face one inclined surface of the trapezoidal elastic member 631. The other inclined surface of the elastic member 631 abuts against the side surface of the protruding portion 15B. Therefore, deformation of the elastic member 631 in a direction away from the fixed portion 630 is restricted by the second extending piece 663 and the side surface of the protruding portion 15B.

[0090] The stopper 620 is fixed to the fixing portion 630 by a bolt (not shown). The structure for fixing the stopper 620 is substantially the same as that of the third embodiment (see FIG. 11), and therefore a description thereof will be omitted.

[0091] According to the stopper structure of the sixth embodiment, it is possible to improve the shock absorption capacity and product protection while suppressing the increase in size of the stopper 620 .

[0092] Seventh Embodiment A seventh embodiment will be described with reference to Fig. 17 and Fig. 18. As shown in Fig. 17, in the stopper structure according to the seventh embodiment, a rotation restricting portion 716 is provided separately from the base 11 (an example of a support portion) and contacts the robot arm 12 to restrict rotation when the robot arm 12 rotates to the end of its rotation range. Two rotation restricting portions 716 may be provided. The two rotation restricting portions 716 may be arranged symmetrically in Fig. 17.

[0093] 18, the rotation restricting portion 716 includes a pillar portion 716A that rises upward and a base 716B that is provided below the pillar portion 716A. The base 716B is fixed with bolts or the like to a workbench to which the base 11 is fixed. A cylindrical fixing portion is provided on the upper surface of the rotation restricting portion 716, similar to the fixing portion 530 (see FIG. 15) shown in the above-described fifth embodiment. The shape of the rotation restricting portion 716 is not limited to a pillar shape and may be other shapes.

[0094] A stopper 720 is provided on the upper surface of the rotation restricting portion 716. The structure of the stopper 720 according to the seventh embodiment is substantially the same as that of the stopper 520 according to the fifth embodiment, and includes an elastic member 531. The stopper 720 is fixed to a fixing portion provided on the upper surface of the rotation restricting portion 716 by a bolt. The structure of the stopper 720 is not limited to this, and may have another shape. For example, the stopper 720 may have substantially the same structure as the stoppers according to the first to fourth or sixth embodiments. The shape of the fixing portion is not limited to a cylindrical shape, and may have another shape.

[0095] According to the stopper structure of the seventh embodiment, it is possible to improve the shock absorption capacity and product protection while suppressing the increase in size of the stopper 720.

[0096] <Other Embodiments> The technology disclosed in this specification is not limited to the embodiments described above and in the drawings, and for example, the following embodiments are also included in the technical scope disclosed in this specification.

[0097] (1) In the above-described first embodiment, the metal member is the sheet metal member 35, which includes the first extending piece 62 and the second extending piece 63. However, the sheet metal member 35 may include only one of the first extending piece 62 or the second extending piece 63.

[0098] (2) In the above embodiment, the first extension piece 62 is composed of two pieces, the first extension piece 62A and the first extension piece 62B, and these two first extension pieces 62A and 62B are not connected. In contrast, these two first extension pieces 62A and 62B may be connected. In that case, the second fitting hole 34A and the second fitting hole 34B of the elastic member 31 are formed as a single connected fitting hole.

[0099] (3) In the above embodiment, the metal member is the sheet metal member 35, but the metal member does not have to be the sheet metal member 35. For example, the metal member may be a member formed by die casting, sand casting, or the like. Even in this case, by setting the thickness and material of the first extension piece 62 and the second extension piece 63, the first extension piece 62 and the second extension piece 63 can be formed to be elastically deformable.

[0100] (4) In the above embodiment, the metal member is provided with the elastically deformable first extension piece 62 and second extension piece 63. However, the metal member may be a member having a thickness or material that is less prone to elastic deformation than the sheet metal member 35. In this case, the metal member may not include a member corresponding to the first extension piece 62, but may include a portion that is less prone to elastic deformation corresponding to the second extension piece 63. This restricts deformation of the elastic member 31, thereby improving the shock absorption capacity compared to a case in which no metal member is included.

[0101] (5) In the above-described first embodiment, the first extension piece 62 is plastically deformed when a collision load 80 greater than a predetermined value acts from the abutment portion 16. However, the first extension piece does not have to be plastically deformed.

[0102] (6) In the above embodiment, the number of second extension pieces 63 is two. However, the number of second extension pieces 63 may be one, or may be three or more.

[0103] (7) In the above-described first embodiment, the base 11 restricts the rotation of the robot arm 12. However, a rotation restricting unit provided separately from the base 11 may restrict the rotation of the robot arm 12. For example, a pillar similar to the pillar 716A of the fifth embodiment may be provided as a rotation restricting unit separate from the base 11 of the first embodiment, and the stopper 20 of the robot arm 12 may come into contact with the pillar to restrict the rotation.

[0104] (8) In the above embodiment, a SCARA robot was used as an example of a robot equipped with a stopper structure for a robot arm. However, the robot is not limited to a SCARA robot and may be another type of robot.

[0105] (9) In the above-described sixth and seventh embodiments, the side surface of the robot arm 12 abuts against the stopper. However, for example, a protrusion protruding downward from the bottom surface of the robot arm 12 may be provided, and the protrusion may abut against the stopper.

[0106] (10) In the seventh embodiment, the rotation restricting portion 716 is provided separately from the base main body 15. However, the rotation restricting portion 716 may be provided integrally with the base main body 15. For example, the base 15D (see FIG. 17 ) of the base main body 15 may be extended to below the rotation restricting portion 716, and the rotation restricting portion 716 may be fixed onto the base 15D.

[0107] (11) In the seventh embodiment described above, the rotation restricting portion 716 is spaced apart from the base main body 15, and the elastic member 531 of the stopper 720 does not abut against the base main body 15. However, the rotation restricting portion 716 may be provided closer to the base main body 15, and one end of the elastic member 531 that does not abut against the robot arm 12 may abut against the base main body 15. In this case, the elastic member 531 is compressed by the robot arm 12 and a fixing portion provided on the rotation restricting portion 716, and is also compressed by the fixing portion provided on the rotation restricting portion 716 and the base main body 15. The base main body 15 prevents the elastic member 531 from deforming in a direction away from the fixing portion.

[0108] (12) In the metal member described in the above embodiment, the portion that is inserted into the fitting hole formed in the elastic member (for example, the first extension piece 62 in the case of embodiment 1) may be fitted in advance when the elastic member is molded. In the elastic member, the space into which the metal member is fitted may be a completely closed shape or a shape close to a completely closed shape.

[0109] (13) In the above embodiment, the robot arm 12 is provided with one stopper, and the one stopper abuts against the rotation restricting portion when the robot arm 12 rotates to one end of the rotation range and when the robot arm 12 rotates to the other end. In contrast, the robot arm 20 may be provided with separate stoppers: one stopper that abuts against the rotation restricting portion when the robot arm 12 rotates to one end of the rotation range, and another stopper that abuts against the rotation restricting portion when the robot arm 12 rotates to the other end.

[0110] 1: Picking robot (an example of a robot) 12: Robot arm 11: Base (an example of a support part) 20: Stopper 30: Fixed part 31: Elastic member 34A: Second fitting hole (an example of a fitting hole) 34B: Second fitting hole (an example of a fitting hole) 35: Sheet metal member (an example of a metal member) 80: Collision load 220: Stopper 221: Fixed part 222: Elastic member 223: Sheet metal member (an example of a metal member) 320: Stopper 330: Fixed part 331: Elastic member 334A: Second fitting hole (an example of a fitting hole) 334B: Second fitting hole (an example of a fitting hole) 335: Sheet metal member (an example of a metal member) 420: Stopper 430: Fixed part 431: Elastic member 431A: Fitting hole 435: Metal member 520: Stopper 530: Fixed portion 531: Elastic member 531A: Fitting hole 535: Metal member 620: Stopper 630: Fixed portion 631: Elastic member 634: Fitting hole 635: Sheet metal member (an example of a metal member) 716: Rotation restricting portion 720: Stopper

Claims

1. A stopper structure for a robot arm, comprising: a robot arm; and a support part that rotatably supports the robot arm and abuts against the robot arm to restrict rotation when the robot arm rotates to the end of its rotation range, wherein the robot arm has a stopper that abuts against the support part, and the stopper has: an elastic member that abuts against the support part when the robot arm rotates to the end of its rotation range and is compressed by a fixed part provided on the robot arm and the support part; and a metal member that fits into the elastic member, wherein the metal member is provided in a position where it does not come into contact with the support part.

2. A stopper structure for a robot arm as described in claim 1, wherein the metal member is inserted into a fitting hole formed in the elastic member, the fitting hole is provided at a position that is between the fixed part and the support part when the robot arm is rotated to the end of its rotation range, and the metal member is elastically deformed by a collision load from the support part when the robot arm is rotated to the end of its rotation range.

3. A stopper structure for a robot arm as described in claim 2, wherein the metal member undergoes plastic deformation when the stopper collides with the support part and a collision load of a predetermined value or greater is applied from the support part via the elastic member.

4. A stopper structure for a robot arm as set forth in any one of claims 1 to 3, wherein the metal member is fitted to the elastic member from the outside, and restricts the elastic member from deforming in a direction away from the fixed part when the stopper collides with the support part.

5. A stopper structure for a robot arm, comprising: a robot arm; a support part that rotatably supports the robot arm; and a rotation restriction part that abuts against the robot arm when the robot arm rotates to the end of its rotation range to restrict its rotation, wherein the robot arm has a stopper that abuts against the rotation restriction part, and the stopper has: an elastic member that abuts against the rotation restriction part when the robot arm rotates to the end of its rotation range and is compressed by a fixed part provided on the robot arm and the rotation restriction part; and a metal member that fits into the elastic member, wherein the metal member is provided in a position where it does not come into contact with the rotation restriction part.

6. A stopper structure for a robot arm, comprising: a robot arm; and a support part that rotatably supports the robot arm, wherein the support part has a stopper that abuts against the robot arm to restrict rotation when the robot arm rotates to the end of its rotation range, and the stopper has: an elastic member that abuts against the robot arm when the robot arm rotates to the end of its rotation range and is compressed by a fixing part provided on the support part and the robot arm; and a metal member that fits into the elastic member, wherein the metal member is provided in a position where it does not come into contact with the robot arm.

7. A stopper structure for a robot arm, comprising: a robot arm; a support part that rotatably supports the robot arm; and a rotation restriction part that abuts against the robot arm when the robot arm rotates to the end of its rotation range to restrict the rotation, wherein the rotation restriction part has a stopper that abuts against the robot arm, and the stopper has: an elastic member that abuts against the robot arm when the robot arm rotates to the end of its rotation range and is compressed by a fixing part provided on the rotation restriction part and the robot arm; and a metal member that fits into the elastic member, wherein the metal member is provided in a position where it does not come into contact with the robot arm.

8. A robot equipped with the stopper structure for a robot arm according to claim 1, claim 5, claim 6 or claim 7.

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