Robot arm

Abstract

To materialize advancing / retracting of an arm housing without exposing an advancing / retreating actuator to the outside.SOLUTION: A robot arm 3 comprises: a cylindrical first arm housing 31; a cylindrical second arm housing 32 housed in the first arm housing 31; a first pulley holder 41 arranged in the first arm housing 31; a pair of first pulleys 45 supported by the first pulley holder 41; and a first belt 51 wound around the pair of first pulleys 45. The first pulley holder 41 supports the pair of first pulleys 45 and is mounted to the first arm housing 31 in such a manner that the first end portion 41a at an advance-side in an advancing / retreating direction functions as a free end. The free end of the first pulley holder 41 is housed in the second arm housing 32 through an opening 32b of the second arm housing 32. The first belt 51 is connected to the second arm housing 32, in the second arm housing 32.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The technology disclosed herein relates to a robot arm. [Background technology]

[0002] Conventionally, robot arms that perform telescopic movements are known. For example, Patent Document 1 discloses a robot arm with a telescopic structure. The robot arm has a plurality of cylindrical bodies with different diameters, a plurality of pulleys attached to the plurality of cylindrical bodies, a wire wound around the plurality of pulleys, and a servo motor that winds up the wire. When the servo motor winds up the wire, each of the plurality of cylindrical bodies advances sequentially to the tip side of the robot arm, and the robot arm extends. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-203289 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the robot arm described in Patent Document 1, most of the upper wall of the cylindrical body (i.e., arm housing) is cut out in order to place a pulley or other advance / retract actuator. In other words, the pulley or other advance / retract actuator is exposed to the outside. In this case, the user needs to take care to ensure that the advance / retract actuator does not interfere with the external environment.

[0005] The technology disclosed herein has been made in consideration of the above points, and its purpose is to achieve advancement and retraction of the arm housing without exposing the advancement and retraction actuator to the outside. [Means for solving the problem]

[0006] The robot arm disclosed herein comprises a cylindrical first arm housing extending in a predetermined forward / backward direction and having an opening at an end on the forward / backward side in the forward / backward direction, a cylindrical second arm housing extending in the forward / backward direction and accommodated in the first arm housing so as to be able to move forward and backward in the forward / backward direction through the opening of the first arm housing, a first pulley holder disposed within the first arm housing, a pair of first pulleys supported by the first pulley holder, and a first belt wound around the pair of first pulleys, the first pulley holder supports the pair of first pulleys so that the pair of first pulleys are aligned in the forward / backward direction and is attached to the first arm housing so that the end on the forward / backward side in the forward / backward direction is a free end, the second arm housing has an opening at an end on the backward side in the forward / backward direction, the free end of the first pulley holder is accommodated in the second arm housing through the opening of the second arm housing, and the first belt is connected to the second arm housing within the second arm housing. Effect of the Invention

[0007] The robot arm achieves advancement and retreat of the arm housing without exposing the advancement and retreat actuator to the outside. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a robot. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a picking operation. [Diagram 3] FIG. 3 is a perspective view of the robot arm in an extended state. [Figure 4] FIG. 4 is a perspective view of the robot arm in a retracted state. [Diagram 5] FIG. 5 is a perspective view of the robot arm with a portion of the outer wall thereof omitted. [Figure 6] FIG. 6 is a front view of the robot arm. [Figure 7] FIG. 7 is an exploded perspective view of the robot arm. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 10 is a perspective view of a robot arm according to a modified example. [Figure 11] FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 12 is a cross-sectional view of a robot arm in a contracted state according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An exemplary embodiment will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing a robot 1. The robot 1 performs a picking operation. Specifically, the robot 1 picks up a workpiece W from a first container C1 placed on a shelf S, and transfers the workpiece W to a second container C2. The first container C1 is a source container that contains the workpiece W. The second container C2 is a destination container that contains the workpiece W.

[0010] The shelf S has a plurality of shelf boards S1 arranged at intervals in the vertical direction. The first container C1 is placed on the shelf boards S1. On the shelf S, a working space H into which the robot arm 3 can enter is present between the first container C1 and the shelf board S1 located above the first container C1.

[0011] The robot 1 includes a cart 11, an elevator 12 placed on the cart 11, a robot arm 3 attached to the elevator 12, a robot wrist 7 attached to the tip of the robot arm 3, and a hand 8 attached to the robot wrist 7. Hereinafter, the robot wrist 7 will also be referred to simply as "wrist 7".

[0012] The robot 1 moves by traveling on a cart 11. The cart 11 is, for example, an AGV (Automated Guided Vehicle). In this example, the cart 11 carries a second container C2.

[0013] The elevator 12 raises and lowers the robot arm 3 and rotates it. In this example, the elevator 12 has a support 12a. The support 12a has an axis extending in the vertical direction. The axis of the support 12a is also referred to as the lifting axis P. The support 12a is attached to the cart 11 so as to be rotatable around the lifting axis P. The support 12a supports the robot arm 3 so as to be movable along the lifting axis P. The elevator 12 has a linear actuator that moves the robot arm 3 along the lifting axis P, and a rotary actuator that rotates the support 12a around the lifting axis P. That is, the elevator 12 moves the robot arm 3 along the lifting axis P by the linear actuator. The elevator 12 rotates the support 12a, and therefore the robot arm 3, around the lifting axis P by the rotary actuator.

[0014] The robot arm 3 is a linear-acting telescopic arm. The robot arm 3 telescopes in the direction of a predetermined advance / retract axis Q. The robot arm 3 moves the wrist 7 and hand 8 by telescopically extending. Specifically, the robot arm 3 has multiple cylindrical arm housings. The axis of each arm housing coincides with the advance / retract axis Q. The multiple arm housings are nested. The multiple arm housings are capable of moving relative to one another in the direction of the advance / retract axis Q. The robot arm 3 has a linear actuator that moves the multiple arm housings relative to one another. The multiple arm housings move relatively in the direction of the advance / retract axis Q, causing the robot arm 3 to extend and retract in the direction of the advance / retract axis Q.

[0015] The robot arm 3 is supported by the elevator 12 with the advance / retract axis Q intersecting the lift axis P. Specifically, the advance / retract axis Q is perpendicular to the lift axis P. The advance / retract axis Q may be disposed at a skewed position with respect to the lift axis P.

[0016] The wrist 7 moves the hand 8 relative to the robot arm 3. The wrist 7 is attached to the tip of the robot arm 3.

[0017] The hand 8 holds the workpiece W. The form of holding by the hand 8 is arbitrary. For example, holding by the hand 8 may be by gripping or suction. In this example, the hand 8 grips the workpiece W. The hand 8 has a hand body 81 and a plurality of fingers 82 attached to the hand body 81. The hand 8 opens and closes the plurality of fingers 82.

[0018] A picking operation by the robot 1 will be briefly described below. FIG. 2 is a schematic diagram for explaining the movement of the wrist 7 and the hand 8 inside a container during a picking operation. As shown in FIG. 1, the robot 1 moves to a position facing the shelf S by traveling the cart 11. At this time, the elevator 12 moves the robot arm 3 so that the hand 8 is positioned at a predetermined entry start position. The entry start position is a position where the hand 8 faces the working space H between the target first container C1 and the shelf board S1 located above the first container C1.

[0019] Next, the robot 1 extends the robot arm 3, thereby causing the robot arm 3 to enter the workspace H. As a result, the wrist 7 and the hand 8 enter the workspace H. At this time, the hand 8 is positioned above the workpiece W to be picked in the first container C1.

[0020] 2, the robot 1 moves the hand 8 into the first container C1. For example, the robot 1 moves the hand 8 via the wrist 7 in a direction intersecting with the forward / backward axis Q of the robot arm 3, and causes the hand 8 to enter the first container C1. Then, the robot 1 grips the workpiece W to be picked with the fingers 82 of the hand 8.

[0021] When the gripping is completed, the robot 1 moves the hand 8 above the first container C1, i.e., to the working space H. From that state, the robot 1 retracts the robot arm 3 and moves the hand 8 together with the workpiece W back from the working space H.

[0022] Thereafter, the elevator 12 rotates and raises and lowers the robot arm 3 to move the hand 8 above the second container C2. The robot 1 moves the hand 8 into the second container C2. The robot 1 places the workpiece W in the second container C2 by releasing the grip of the workpiece W by the fingers 82 of the hand 8. In this way, the workpiece W to be picked is transferred from the first container C1 to the second container C2.

[0023] Next, the robot arm 3 will be described in detail. Fig. 3 is a perspective view of the robot arm 3 in an extended state. Fig. 4 is a perspective view of the robot arm 3 in a contracted state. Fig. 5 is a perspective view of the robot arm 3 with part of the outer wall thereof omitted. Figs. 3 and 5 depict the robot arm 3 in its most extended state, and Fig. 4 depicts the robot arm 3 in its most contracted state. Hereinafter, the most extended state of the robot arm 3 will be referred to simply as the "longest state", and the most contracted state of the robot arm 3 will be referred to simply as the "shortest state".

[0024] The robot arm 3 is an expandable arm having a telescopic structure. The robot arm 3 changes between a maximum length state and a minimum length state. The robot arm 3 includes a cylindrical first arm housing 31 extending in a predetermined advancing / retreating direction, a cylindrical second arm housing 32 extending in the advancing / retreating direction and accommodated in the first arm housing 31 so as to be movable in the advancing / retreating direction, and an advancing / retreating actuator (specifically, a linear actuator) for advancing / retreating the second arm housing 32. The second arm housing 32 advances from the first arm housing 31 in the advancing / retreating direction and retreats to the first arm housing 31 in the advancing / retreating direction. The second arm housing 32 advances from the first arm housing 31, causing the robot arm 3 to extend as a whole. The second arm housing 32 retreats to the first arm housing 31, causing the robot arm 3 to contract as a whole.

[0025] That is, the "advance / retraction direction" is the movement direction of the second arm housing 32 and also the extension / retraction direction of the robot arm 3. In this example, the advance / retraction direction coincides with the direction of the advance / retraction axis Q described above. The side in the advance / retraction direction from which the second arm housing 32 advances is simply referred to as the "advance side", and the side in the advance / retraction direction from which the second arm housing 32 retreats is simply referred to as the "retreat side". In this example, the advance / retraction direction is substantially horizontal. Hereinafter, a direction that is substantially perpendicular to the advance / retraction direction and substantially horizontal is referred to as the "width direction". A substantially vertical direction is also referred to as the "up / down direction". In addition, moving to the advance side in the advance / retraction direction is simply referred to as "advance", and moving to the retreat side in the advance / retraction direction is simply referred to as "retreat".

[0026] The forward / backward actuator includes a first pulley holder 41, a first pulley 45, and a first belt 51. As shown in FIG. 5, the first pulley holder 41 is disposed in the first arm housing 31. The pair of first pulleys 45 are supported by the first pulley holder 41. The first belt 51 is wound around the pair of first pulleys 45 and is connected to the second arm housing 32 via a second pulley holder 42 described later. A rotational driving force of a motor is applied to one of the first pulleys 45. For example, the motor is a servo motor and is disposed in the first arm housing 31. The rotational driving force of the motor is transmitted to one of the first pulleys 45 via a belt or a gear train. The first pulley 45 is rotated to rotate the first belt 51, and the second arm housing 32 advances and retreats in conjunction with the first belt 51.

[0027] In this example, the robot arm 3 further includes a third arm housing 33 that is tubular extending in the advancing / retreating direction and is accommodated in the second arm housing 32 so as to be movable in the advancing / retreating direction. The advancing / retreating actuator further includes a second pulley holder 42, a second pulley 46, and a second belt 52. The second pulley holder 42, the second pulley 46, and the second belt 52 are interlocked with the first pulley holder 41, the first pulley 45, and the first belt 51. The advancing / retreating actuator advances and retreats the third arm housing 33 in addition to the second arm housing 32. The third arm housing 33 advances from the second arm housing 32 in the advancing / retreating direction and retreats to the second arm housing 32 in the advancing / retreating direction. When the second arm housing 32 advances from the first arm housing 31, the third arm housing 33 advances from the second arm housing 32. This causes the robot arm 3 to extend as a whole. When the second arm housing 32 retracts into the first arm housing 31, the third arm housing 33 retracts into the second arm housing 32. This causes the robot arm 3 to contract as a whole.

[0028] The second pulley holder 42 is disposed in the second arm housing 32. The pair of second pulleys 46 are supported by the second pulley holder 42. The second belt 52 is wound around the pair of second pulleys and is connected to the third arm housing 33. When the second belt 52 rotates, the third arm housing 33 moves forward and backward in conjunction with the second belt 52.

[0029] More specifically, the respective axes of the first arm housing 31, the second arm housing 32, and the third arm housing 33 extend in the forward and backward directions. The first arm housing 31, the second arm housing 32, and the third arm housing 33 are assembled in a nested manner. The first arm housing 31 has an opening 31a at the forward end. The backward end of the first arm housing 31 is attached to the elevator 2 (see FIG. 1). The second arm housing 32 is accommodated in the first arm housing 31 so as to be able to move forward and backward in the forward and backward directions via the opening 31a of the first arm housing 31. The second arm housing 32 has an opening 32b at the backward end. The second arm housing 32 has an opening 32a at the forward end. The third arm housing 33 is accommodated in the second arm housing 32 so as to be able to move forward and backward in the forward and backward directions via the opening 32a of the second arm housing 32. The third arm housing 33 has an opening 33b at the backward end. The third arm housing 33 has an opening 33a at the end on the advancing side.

[0030] FIG. 6 is a front view of the robot arm 3. In this example, the front refers to a surface facing the advancing side. In a cross section perpendicular to the advancing / retreating direction, the size of the first arm housing 31 is larger than the size of the second arm housing 32, and the size of the second arm housing 32 is larger than the size of the third arm housing 33. In detail, the cross-sectional shape of the first arm housing 31 perpendicular to the advancing / retreating direction is a closed cross-sectional shape having a chamfered first corner portion 31c. The cross-sectional shape of the second arm housing 32 perpendicular to the advancing / retreating direction is a closed cross-sectional shape having a chamfered second corner portion 32c. The cross-sectional shape of the third arm housing 33 perpendicular to the advancing / retreating direction is a closed cross-sectional shape having a chamfered third corner portion 33c. The first corner portion 31c of the first arm housing 31 faces the second corner portion 32c of the second arm housing 32. The second corner portion 32c of the second arm housing 32 faces the third corner portion 33c of the third arm housing 33.

[0031] That is, the first arm housing 31, the second arm housing 32, and the third arm housing 33 are each a square tube with chamfered corners. Specifically, the cross-sectional shape of each of the first arm housing 31, the second arm housing 32, and the third arm housing 33 is an octagon. More specifically, the first arm housing 31 includes four first corners 31c and four flat plates 31d. Each two adjacent flat plates 31d are connected by the corresponding first corners 31c. The second arm housing 32 includes four second corners 32c and four flat plates 32d. Each two adjacent flat plates 32d are connected by the corresponding second corners 32c. The third arm housing 33 includes four third corners 33c and four flat plates 33d. Each two adjacent flat plates 33d are connected by the corresponding third corners 33c.

[0032] FIG. 7 is an exploded perspective view of the robot arm 3. For convenience of explanation, the first belt 51 and the second belt 52 are omitted in FIG. 7. The robot arm 3 further includes a first sliding guide 35 arranged inside the first arm housing 31 and a first sliding block 36 arranged on the outer surface of the second arm housing 32. The first sliding guide 35 extends in the forward and backward direction. The first sliding block 36 slides against the first sliding guide 35 when the second arm housing 32 advances and retreats relative to the first arm housing 31. The first sliding guide 35 is an example of a sliding guide. The first sliding block 36 is an example of a sliding block.

[0033] The robot arm 3 further includes a second sliding guide 37 disposed inside the second arm housing 32, and a second sliding block 38 disposed on the outer surface of the third arm housing 33. The second sliding guide 37 extends in the forward and backward direction. The second sliding block 38 slides relative to the second sliding guide 37 when the third arm housing 33 advances or retreats relative to the second arm housing 32.

[0034] The first sliding block 36 is disposed in a portion of the second arm housing 32 that overlaps with the first arm housing 31 when the second arm housing 32 is in a state where it is maximally extended from the first arm housing 31. In other words, the first sliding block 36 is covered by the first arm housing 31 and is not exposed to the outside when the second arm housing 32 is in a state where it is maximally extended from the first arm housing 31. The second sliding block 38 is disposed in a portion of the third arm housing 33 that overlaps with the second arm housing 32 when the third arm housing 33 is in a state where it is maximally extended from the second arm housing 32. In other words, the second sliding block 38 is covered by the second arm housing 32 and is not exposed to the outside when the third arm housing 33 is in a state where it is maximally extended from the second arm housing 32.

[0035] In this example, the first sliding block 36 and the second sliding block 38 are each shaped like a rectangular plate in a plan view. The first sliding block 36 and the second sliding block 38 are each made of, for example, metal or resin. The first sliding guide 35 and the second sliding guide 37 are each made of, for example, metal or resin.

[0036] The first sliding blocks 36 are disposed on the outer surface of the second corners 32c of the second arm housing 32. In this example, the first sliding blocks 36 are disposed at all four second corners 32c. At each second corner 32c, two first sliding blocks 36 are arranged side by side in the forward / backward direction. That is, the number of first sliding blocks 36 is eight in total.

[0037] The first sliding guide 35 is disposed on the inner surface of the first corner portion 31c of the first arm housing 31. The first sliding guide 35 has a length sufficient to make sufficient contact with the first sliding block 36 when the robot arm 3 transitions between the shortest state and the longest state. In this example, the first sliding guide 35 extends over substantially the entirety of the first arm housing 31 in the forward and backward movement direction.

[0038] The second sliding blocks 38 are disposed on the outer surface of the third corners 33c of the third arm housing 33. In this example, the second sliding blocks 38 are disposed at all four third corners 33c. At each third corner 33c, two second sliding blocks 38 are arranged side by side in the forward / backward direction. That is, the number of second sliding blocks 38 is eight in total.

[0039] The second sliding guide 37 is disposed on the inner surface of the second corner portion 32c of the second arm housing 32. The second sliding guide 37 has a length sufficient to make contact with the second sliding block 38 when the robot arm 3 transitions between the shortest state and the longest state. In this example, the second sliding guide 37 extends over substantially the entirety of the second arm housing 32 in the forward and backward movement direction.

[0040] As shown in FIG. 6, the distance d1 between the first corner 31c and the second corner 32c, i.e., the interval between the first corner 31c and the second corner 32c, is greater than the distance between the portion of the first arm housing 31 other than the first corner 31c and the portion of the second arm housing 32 other than the second corner 32c. For example, the distance d1 is greater than the distance d2 between the flat plate 31d of the first arm housing 31 and the flat plate 32d of the second arm housing 32. This ensures a space for arranging the first sliding guide 35 and the first sliding block 36 between the first corner 31c and the second corner 32c. The distance d3 between the second corner 32c and the third corner 33c, i.e., the interval between the second corner 32c and the third corner 33c, is greater than the distance between the portion of the second arm housing 32 other than the second corner 32c and the portion of the third arm housing 33 other than the third corner 33c. For example, the distance d3 is greater than the distance d4 between the flat plate 32d of the second arm housing 32 and the flat plate 33d of the third arm housing 33. This makes it possible to ensure a space for disposing the second sliding guide 37 and the second sliding block 38 between the second corner portion 32c and the third corner portion 33c.

[0041] Next, the configurations of the first pulley holder 41, the first pulley 45, and the first belt 51 will be described in detail. In this example, the first belt 51 is a timing belt, and the first pulley 45 is a timing pulley. As shown in Fig. 5, the first pulley holder 41 supports the pair of first pulleys 45 so that the pair of first pulleys 45 are aligned in the forward and backward direction. The first pulley holder 41 is attached to the first arm housing 31 so that the first end 41a on the forward side is a free end.

[0042] Specifically, the first pulley holder 41 extends in the forward and backward directions as a whole. The first pulley holder 41 has a first end 41a on the forward side and a second end 41b on the backward side. The second end 41b is attached to the inner surface of the first arm housing 31. In other words, the first pulley holder 41 is attached to the first arm housing 31 in a cantilevered manner so as to extend in the forward and backward directions. The free end of the first pulley holder 41, i.e., the first end 41a, is accommodated in the second arm housing 32 through the opening 32b of the second arm housing 32 at least when the second arm housing 32 is in the most backward state. In other words, the first end 41a enters the second arm housing 32 beyond the opening 32b at least when the second arm housing 32 is in the most backward state.

[0043] The first pulley holder 41 supports each of the first pulleys 45 rotatably around an axis extending in the width direction. In detail, as shown in FIG. 6, the first pulley holder 41 has a pair of plates 41p attached to the first arm housing 31 in a state of facing each other. The pair of plates 41p supports the pair of first pulleys 45 in a state of sandwiching them. As shown in FIG. 5, the first pulleys 45 are disposed at the first end 41a and the second end 41b of the first pulley holder 41. The pair of plates 41p rotatably support each of the first pulleys 45 via a first shaft 47 extending in the width direction.

[0044] More specifically, the first pulley holder 41 is attached to the first arm housing 31 via a first bracket 55. Specifically, as shown in FIG. 6, the first bracket 55 extends in the width direction along the lower flat plate 31d of the first arm housing 31 and is attached to the two lower first corners 31c. Both ends of the first bracket 55 in the width direction are bent corresponding to the first corners 31c. Both ends of the first bracket 55 in the width direction are attached to the first corners 31c by, for example, bolts or the like. The approximate center of the first bracket 55 in the width direction is attached to the first pulley holder 41 by, for example, welding or the like. In FIG. 6, for convenience of explanation, the first bracket 55, a second bracket 56 described later, and a third bracket 57 described later are drawn with two-dot chain lines, and the first belt 51 and the second belt 52 are each marked with a dot. The first bracket 55 is an example of a bracket.

[0045] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 3. The first belt 51 is an endless belt. The first belt 51 rotates around a pair of first pulleys 45. A portion of the first belt 51 between the pair of first pulleys 45 extends in the forward and backward direction, and moves in the forward and backward direction when the first belt 51 rotates. Hereinafter, the portion of the first belt 51 between the pair of first pulleys 45 is referred to as a flat portion. This flat portion extends substantially flat and may include some bending. The first belt 51 has a first flat portion 51A and a second flat portion 51B facing each other. The first flat portion 51A is close to the second belt 52, and the second flat portion 51B is close to the lower flat plate 31d (see FIG. 6) of the first arm housing 31. The first flat portion 51A and the second flat portion 51B move in the forward and backward direction in opposite directions when the first belt 51 rotates. For example, when the first flat portion 51A advances, the second flat portion 51B retreats.

[0046] The second pulley holder 42 is attached to the first flat portion 51A. In more detail, a second end 42b of the second pulley holder 42, which will be described later, is connected to the first flat portion 51A via a connector 43.

[0047] Next, the configurations of the second pulley holder 42, the second pulley 46, and the second belt 52 will be described in detail. In this example, the second belt 52 is a timing belt, and the second pulley 46 is a timing pulley. As shown in Fig. 5, the second pulley holder 42 supports the pair of second pulleys 46 so that the pair of second pulleys 46 are aligned in the forward and backward direction. The second pulley holder 42 is disposed in the second arm housing 32. In terms of the vertical position, the second pulley holder 42 is disposed above the first pulley holder 41.

[0048] Specifically, the second pulley holder 42 extends generally in the forward and backward directions. The second pulley holder 42 has a first end 42a on the forward side and a second end 42b on the backward side. The second end 42b is attached to the inner surface of the second arm housing 32 and is attached to the first belt 51 via a connector 43. In other words, the first belt 51 is connected to the second arm housing 32 via the second pulley holder 42.

[0049] In short, the second pulley holder 42 extends in the forward / backward direction and is attached to the second arm housing 32 in a cantilevered manner such that the first end 42a on the forward side is a free end. The first end 42a, which is the free end, is accommodated in the third arm housing 33 through the opening 33b of the third arm housing 33, at least when the third arm housing 33 is in the most backward state. In other words, the first end 42a enters the third arm housing 33 beyond the opening 33b, at least when the third arm housing 33 is in the most backward state.

[0050] The second pulley holder 42 supports each of the second pulleys 46 rotatably around an axis extending in the width direction. In detail, as shown in FIG. 6, the second pulley holder 42 has a pair of plates 42p attached to the second arm housing 32 in a state facing each other in the width direction. The pair of plates 42p supports the pair of second pulleys 46 in a sandwiched state. As shown in FIG. 5, the second pulleys 46 are disposed at the first end 42a and the second end 42b of the second pulley holder 42. The pair of plates 42p rotatably support each of the second pulleys 46 via a second shaft 48 extending in the width direction.

[0051] More specifically, as shown in FIG. 6, the second pulley holder 42 is attached to the second arm housing 32 via a second bracket 56. Specifically, the second bracket 56 extends in the width direction along the upper flat plate 32d of the second arm housing 32, and is attached to the two upper second corners 32c. Both ends of the second bracket 56 in the width direction are bent to correspond to the second corners 32c. Both ends of the second bracket 56 in the width direction are attached to the second corners 32c by, for example, bolts. The approximate center of the second bracket 56 in the width direction is attached to the second pulley holder 42 by, for example, welding.

[0052] As shown in FIG. 8, the second belt 52 is an endless belt. The second belt 52 rotates around the pair of second pulleys 46. The portion of the second belt 52 between the pair of second pulleys 46 extends in the forward and backward direction, and moves in the forward and backward direction when the second belt 52 rotates. Hereinafter, the portion of the second belt 52 between the pair of second pulleys 46 is referred to as a flat portion. Note that this flat portion extends substantially flat and may include some bending. The second belt 52 has a first flat portion 52A and a second flat portion 52B facing each other. The first flat portion 52A is close to the upper flat plate 32d (see FIG. 6) of the second arm housing 32, and the second flat portion 52B is close to the first belt 51. The first flat portion 52A and the second flat portion 52B move in the forward and backward direction in opposite directions when the second belt 52 rotates. For example, when the first flat portion 52A advances, the second flat portion 52B retreats.

[0053] The first pulley holder 41 is attached to the second flat portion 52B. More specifically, the first end 41a of the first pulley holder 41 is connected to the second flat portion 52B via a connector 43.

[0054] The second belt 52 is connected to the third arm housing 33 inside the third arm housing 33. More specifically, the second belt 52 is connected to the third arm housing 33 via a third bracket 57. As shown in FIG. 6, the third bracket 57 extends in the width direction along the upper flat plate 33d of the third arm housing 33 and is attached to the two upper third corners 33c. Both ends of the third bracket 57 in the width direction are bent corresponding to the third corners 33c. Both ends of the third bracket 57 in the width direction are attached to the third corners 33c using, for example, bolts. An approximately central portion of the third bracket 57 in the width direction is attached to the first flat portion 52A of the second belt 52.

[0055] Next, a description will be given of the operation of the robot arm 3. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 4.

[0056] First, the operation when the robot arm 3 changes from the shortest state to the longest state will be described. In the robot arm 3 in the shortest state shown in FIG. 9, one of the pair of first pulleys 45 is driven to rotate counterclockwise. Accordingly, the first belt 51 rotates counterclockwise around the pair of first pulleys 45. At this time, the first flat portion 51A of the first belt 51 advances, and the second flat portion 51B retreats. As described above, the second arm housing 32 is connected to the first flat portion 51A via the second pulley holder 42 and the like. In the state in which the second arm housing 32 is most retreated, the connection portion of the first belt 51 to the second pulley holder 42 is located at the end of the first flat portion 51A on the retreat side in the advance / retract direction. Therefore, when the first flat portion 51A advances in conjunction with the rotation of the first belt 51, the second pulley holder 42 and the second arm housing 32 also advance. That is, the second arm housing 32 advances relative to the first arm housing 31.

[0057] At this time, the second pulley holder 42 advances integrally with the second arm housing 32. The second pulley 46 and the second belt 52 supported by the second pulley holder 42 also advance relative to the first arm housing 31. The third arm housing 33 connected to the second belt 52 also advances relative to the first arm housing 31 together with the second arm housing 32. However, the second belt 52 is connected to the first pulley holder 41. The first pulley holder 41 is fixed to the first arm housing 31. In other words, even if the second pulley holder 42 advances, the connection portion of the second belt 52 to the first pulley holder 41 does not move. Therefore, the second belt 52 advances as a whole while rotating so as to follow the advancement of the second pulley holder 42. More specifically, when the second arm housing 32 is in the most retreated state, the connecting portion of the second belt 52 to the first pulley holder 41 is located at the end of the second flat portion 52B on the advancing side in the advancing / retreating direction. The connecting portion of the second belt 52 to the third arm housing 33 is located at the end of the first flat portion 52A on the retreating side in the advancing / retreating direction. When the second belt 52 advances as a whole while rotating, the connecting portion of the second belt 52 to the first pulley holder 41 retreats at the second flat portion 52B, and the connecting portion of the second belt 52 to the third arm housing 33 advances at the first flat portion 52A. As a result, the third arm housing 33 advances relative to the second pulley holder 42, i.e., the second arm housing 32.

[0058] In this way, when the second arm housing 32 advances relative to the first arm housing 31, the third arm housing 33 advances relative to the second arm housing 32. As a result, the robot arm 3 changes from the shortest state to the longest state. At this time, the first sliding block 36 slides relative to the first sliding guide 35. The second sliding block 38 slides relative to the second sliding guide 37.

[0059] When the robot arm 3 changes from the maximum length to the minimum length, the opposite operation to that when changing from the minimum length to the maximum length is performed. That is, in the robot arm 3 in the maximum length shown in FIG. 8, one of the pair of first pulleys 45 is rotated clockwise, so that the first flat portion 51A of the first belt 51 retracts, the second flat portion 51B of the first belt 51 advances, the first flat portion 52A of the second belt 52 retracts, and the second flat portion 52B of the second belt 52 advances. As a result, when the second arm housing 32 retracts relative to the first arm housing 31, the third arm housing 33 retracts relative to the second arm housing 32. As a result, the robot arm 3 changes from the maximum length to the minimum length. As in the case of changing from the minimum length to the maximum length, the first sliding block 36 slides relative to the first sliding guide 35, and the second sliding block 38 slides relative to the second sliding guide 37.

[0060] As shown in FIG. 8 and FIG. 9, in both the maximum length and minimum length of the robot arm 3, the first pulley holder 41, the pair of first pulleys 45, the first belt 51, the second pulley holder 42, the pair of second pulleys 46, and the second belt 52 are each covered by one of the arm housings, the first arm housing 31, the second arm housing 32, and the third arm housing 33. That is, in both the maximum length and minimum length of the robot arm 3, the advance / retract actuators such as the first pulley 45 are not exposed to the outside. The advance / retract actuators are not exposed between the maximum length and minimum length of the robot arm 3. Furthermore, in this example, the first sliding block 36 and the second sliding block 38 are also not exposed to the outside. The first sliding guide 35 and the second sliding guide 37 are disposed on the inner surface of the first arm housing 31 and the inner surface of the second arm housing 32, respectively, and therefore are not exposed to the outside.

[0061] In the robot arm 3 configured as described above, the first pulley holder 41, the pair of first pulleys 45, and the first belt 51, which are the forward and backward actuators, can be prevented from being exposed to the outside.

[0062] Specifically, the first pulley holder 41 is attached to the first arm housing 31 in a cantilevered manner within the first arm housing 31. This allows the first pulley holder 41 to be attached to the first arm housing 31 in a state in which it has advanced into the second arm housing 32. By disposing the first pulley holder 41 at least partially within the second arm housing 32, the first belt 51 is also disposed at least partially within the second arm housing 32. By disposing the first belt 51 within the second arm housing 32, connection between the first belt 51 and the second arm housing 32 can be easily achieved. In other words, a configuration in which the second arm housing 32 advances and retreats in accordance with the movement of the first belt 51 can be easily achieved.

[0063] More specifically, the first pulley holder 41 supports a pair of first pulleys 45 so that the pair of first pulleys 45 are aligned in the forward and backward direction. A portion of the first belt 51 between the pair of first pulleys 45, i.e., a first flat portion 51A and a second flat portion 51B, extends in the forward and backward direction. Since the first flat portion 51A and the second flat portion 51B of the first belt 51 are also partially disposed within the second arm housing 32, the first flat portion 51A or the second flat portion 51B can be easily connected to the second arm housing 32. Since the first flat portion 51A and the second flat portion 51B move in the forward and backward direction, the second arm housing 32 can be advanced and retreated by rotating the first belt 51. In this way, the forward and backward movement of the second arm housing 32 can be realized by the first belt 51 and the like while preventing the first pulley holder 41, the pair of first pulleys 45, and the first belt 51 from being exposed to the outside from the first arm housing 31 and the second arm housing 32.

[0064] If the first pulley holder 41 were not attached to the first arm housing 31 in a cantilevered manner, the advance / retract actuator would become larger, and it may become necessary to form, for example, a notch in the outer wall of the first arm housing 31.

[0065] In this example, the robot arm 3 also includes a third arm housing 33, and the second pulley holder 42, the pair of second pulleys 46, and the second belt 52, which are part of the forward / backward actuator, are also not exposed to the outside.

[0066] Specifically, the second pulley holder 42 is attached to the second arm housing 32 in a cantilevered manner within the second arm housing 32. Furthermore, the second pulley holder 42 is connected to the first belt 51. In other words, the connection between the first belt 51 and the second arm housing 32 is realized via the second pulley holder 42. As a result, when the first belt 51 rotates, the second arm housing 32 and the second pulley holder 42 advance and retreat together.

[0067] Furthermore, since the second pulley holder 42 has a cantilever shape, the second pulley holder 42 can be attached to the second arm housing 32 in a state in which it has advanced into the third arm housing 33. Since the second pulley holder 42 is at least partially disposed within the third arm housing 33, the second belt 52 is also at least partially disposed within the third arm housing 33. Since the first flat portion 52A and the second flat portion 52B of the second belt 52 are also partially disposed within the third arm housing 33, the first flat portion 52A or the second flat portion 52B can be easily connected to the third arm housing 33.

[0068] Here, the second belt 52 is also connected to the first pulley holder 41. The connected portion of the second belt 52 with the first pulley holder 41 does not move. Therefore, when the second pulley holder 42 advances and retreats in conjunction with the first belt 51, the second belt 52 advances and retreats integrally with the second pulley holder 42 while rotating. As a result, the first flat portion 52A and the second flat portion 52B of the second belt 52 move in the advance and retreat direction, so that the third arm housing 33 also advances and retreats. In this way, the advance and retreat of the third arm housing 33 can be realized by the second belt 52 and the like while preventing the second pulley holder 42, the pair of second pulleys 46, and the second belt 52 from being exposed to the outside from the second arm housing 32 and the third arm housing 33.

[0069] Since the first pulley holder 41 has a pair of plates 41p, the rigidity of the first pulley holder 41 can be improved compared to when the first pulley holder 41 has, for example, only one plate 41p. Similarly, since the second pulley holder 42 has a pair of plates 42p, the rigidity of the second pulley holder 42 can be improved compared to when the second pulley holder 42 has, for example, only one plate 42p.

[0070] The first pulley holder 41 is connected to the first arm housing 31 via a first bracket 55. Therefore, the first pulley holder 41 can be attached to the first arm housing 31 at a position other than the position of the first pulley holder 41. Furthermore, the strength of the first arm housing 31 can be increased by the first bracket 55. Similarly, the second pulley holder 42 is connected to the second arm housing 32 via a second bracket 56. Therefore, the second pulley holder 42 can be attached to the second arm housing 32 at a position other than the position of the second pulley holder 42. Furthermore, the strength of the second arm housing 32 can be increased by the second bracket 56.

[0071] Furthermore, in the robot arm 3, the first bracket 55 is attached to a first corner 31c of the first arm housing 31. Since the first corner 31c makes it easy to ensure a clearance between the first arm housing 31 and the second arm housing 32, the first pulley holder 41 can be easily attached to the first arm housing 31. Similarly, the second bracket 56 is attached to a second corner 32c of the second arm housing 32. Since the second corner 32c makes it easy to ensure a clearance between the second arm housing 32 and the third arm housing 33, the second pulley holder 42 can be easily attached to the second arm housing 32.

[0072] When the robot arm 3 extends or retracts, the first sliding block 36 slides relative to the first sliding guide 35, and the second sliding block 38 slides relative to the second sliding guide 37. This allows the robot arm 3 to extend or retract smoothly. Furthermore, since the first sliding guide 35 is disposed inside the first arm housing 31, the relatively long first sliding guide 35 can be hidden inside the first arm housing 31. Similarly, since the second sliding guide 37 is disposed inside the second arm housing 32, the relatively long second sliding guide 37 can be hidden inside the second arm housing 32.

[0073] Furthermore, the first sliding block 36 is disposed in a portion of the second arm housing 32 that overlaps with the first arm housing 31 when the second arm housing 32 is in its most advanced state. This makes it possible for the first sliding block 36 to also not be exposed to the outside. Similarly, the second sliding block 38 is disposed in a portion of the third arm housing 33 that overlaps with the second arm housing 32 when the third arm housing 33 is in its most advanced state. This makes it possible for the second sliding block 38 to also not be exposed to the outside.

[0074] Next, a robot arm 300 according to a modified example will be described. The robot arm 300 differs from the robot arm 3 mainly in the number of arm housings and pulley holders. The following description will focus on the differences from the robot arm 3.

[0075] FIG. 10 is a perspective view of the robot arm 300. FIG. 10 shows the robot arm 300 in the most extended state. FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 10. The robot arm 300 includes a first arm housing 331, a second arm housing 332, a first pulley holder 341, a pair of first pulleys 345, and a first belt 351. That is, in this example, the robot arm 300 includes two arm housings and one pulley holder. The configurations of the first arm housing 331, the second arm housing 332, the first pulley holder 341, the pair of first pulleys 345, and the first belt 351 are generally the same as the configurations of the first arm housing 31, the third arm housing 33, the first pulley holder 41, the pair of first pulleys 45, and the first belt 51 of the robot arm 3, respectively. Therefore, detailed descriptions of each of these configurations will be omitted.

[0076] The first belt 351 is connected to the second arm housing 332 inside the second arm housing 332. More specifically, a first flat portion 351A of the first belt 351 is connected to the second arm housing 332 via a third bracket 357. The manner in which the first belt 351 is connected to the second arm housing 332 is generally the same as the manner in which the second belt 52 is connected to the third arm housing 33 in the robot arm 3, and therefore a detailed description thereof will be omitted.

[0077] Next, a description will be given of the operation of the robot arm 300. Fig. 12 is a cross-sectional view of the robot arm 300 in the shortest state.

[0078] First, the operation when the robot arm 300 changes from the shortest state to the longest state will be described. In the robot arm 300 in the shortest state shown in FIG. 12, one of the pair of first pulleys 345 is rotated counterclockwise. Accordingly, the first belt 351 rotates counterclockwise around the pair of first pulleys 345. At this time, the first flat portion 51A of the first belt 351 advances, and the second flat portion 351B retreats. As described above, the second arm housing 332 is connected to the first flat portion 351A via the third bracket 357. In the state in which the second arm housing 332 is retreated to the most retreated position, the connection portion of the first belt 351 to the second arm housing 332 is located at the end of the first flat portion 351A on the retreat side in the advance / retract direction. Therefore, when the first flat portion 351A advances in conjunction with the rotation of the first belt 351, the second arm housing 332 also advances.

[0079] When the robot arm 300 changes from the maximum length to the minimum length, the opposite operation to that when changing from the minimum length to the maximum length is performed. That is, in the robot arm 300 in the maximum length state shown in Fig. 11, one of the pair of first pulleys 345 is rotated clockwise, so that the first flat portion 351A of the first belt 351 retreats and the second flat portion 351B advances. In conjunction with the retreat of the first flat portion 351A, the second arm housing 332 also retreats. As a result, the robot arm 3 changes from the maximum length to the minimum length.

[0080] In the robot arm 300 configured as described above, the first pulley holder 341, the pair of first pulleys 345, and the first belt 351, which are the forward and backward actuators, can be prevented from being exposed to the outside.

[0081] Specifically, the first pulley holder 341 is attached to the first arm housing 331 in a cantilevered manner within the first arm housing 331. This allows the first pulley holder 341 to be attached to the first arm housing 331 in a state in which the first pulley holder 341 has advanced into the second arm housing 332. By disposing the first pulley holder 341 at least partially within the second arm housing 332, the first belt 351 is also disposed at least partially within the second arm housing 332. By disposing the first belt 351 within the second arm housing 332, connection between the first belt 351 and the second arm housing 332 can be easily achieved. In other words, a configuration in which the second arm housing 332 advances and retreats in accordance with the movement of the first belt 351 can be easily achieved.

[0082] More specifically, the first pulley holder 341 supports a pair of first pulleys 345 so that the pair of first pulleys 345 are aligned in the forward and backward direction. A portion of the first belt 351 between the pair of first pulleys 345, i.e., a first flat portion 351A and a second flat portion 351B, extend in the forward and backward direction. Since the first flat portion 351A and the second flat portion 351B of the first belt 351 are also partially disposed within the second arm housing 332, the first flat portion 351A or the second flat portion 351B can be easily connected to the second arm housing 332. Since the first flat portion 351A and the second flat portion 351B move in the forward and backward direction, the second arm housing 332 can be advanced and retreated by rotating the first belt 351. In this way, the first pulley holder 341, the pair of first pulleys 345, and the first belt 351 are not exposed to the outside from the first arm housing 331 and the second arm housing 332, while the second arm housing 332 can be moved forward and backward by the first belt 351 etc.

[0083] Other Embodiments As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, replacements, additions, omissions, etc. are appropriately performed. In addition, it is also possible to combine the components described in the above embodiment to form a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the technology may be included. Therefore, the fact that these non-essential components are described in the attached drawings and detailed description should not immediately be taken to mean that these non-essential components are essential.

[0084] For example, in the above example, the robot arm 3 has the first arm housing 31, the second arm housing 32, and the third arm housing 33, but the number of arm housings is not limited. For example, the robot arm 3 may further have a fourth arm housing. In this case, the robot arm 3 may further have a third pulley holder disposed in the third arm housing 33, a pair of third pulleys supported by the third pulley holder, and a third belt wound around the pair of third pulleys. The third pulley holder may be attached to the third arm housing 33 and the second belt 52 so that the end on the forward side is a free end. The free end of the third pulley holder may be housed in the fourth arm housing through an opening on the backward side of the fourth arm housing. The third belt may be connected to the fourth arm housing within the fourth arm housing.

[0085] There are no limitations on the cross-sectional shape of each of the first arm housing 31, the second arm housing 32, and the third arm housing 33. For example, the cross-sectional shape may be a simple rectangle with no chamfered corners.

[0086] The robot arm 3 may not have the first sliding guide 35, the first sliding block 36, the second sliding guide 37, and the second sliding block 38. In this case, in order to maintain the posture of the robot arm 3 in the longest state, it is preferable that the distance d1 shown in Fig. 6 is substantially the same as the distance d2. Similarly, it is preferable that the distance d3 shown in Fig. 6 is substantially the same as the distance d4.

[0087] The shapes of the first sliding block 36 and the second sliding block 38 are not limited. For example, the shapes of the first sliding block 36 and the second sliding block 38 may be curved shapes such as spherical crown shapes. This makes it possible to reduce the frictional resistance between the first sliding guide 35 and the first sliding block 36 and the frictional resistance between the second sliding guide 37 and the second sliding block 38 compared to the case where the shapes are plate-shaped. Instead of the first sliding guide 35 and the first sliding block 36, a linear guide may be used. Similarly, instead of the second sliding guide 37 and the second sliding block 38, a linear guide may be used.

[0088] In the above example, the first pulley holder 41 has a pair of plates 41p, but the configuration of the first pulley holder 41 is not limited to this. For example, the first pulley holder 41 may be formed of one plate 41p, or may be formed of three or more plates 41p. The same applies to the second pulley holder 42.

[0089] The first pulley holder 41 does not have to be attached to the first arm housing 31 via the first bracket 55. For example, the first pulley holder 41 may be attached directly to the first arm housing 31. Specifically, for example, the connector 43 attached to the second end 41b of the first pulley holder 41 may be bolted to the first arm housing 31. Similarly, the second pulley holder 42 does not have to be attached to the second arm housing 32 via the second bracket 56.

[0090] The first bracket 55 does not have to be attached to the first corner portion 31c of the first arm housing 31. For example, the first bracket 55 may be attached to the lower flat plate 31d of the first arm housing 31. Similarly, the second bracket 56 does not have to be attached to the second corner portion 32c of the second arm housing 32. For example, the second bracket 56 may be attached to the upper flat plate 32d of the second arm housing 32.

[0091] The technology disclosed herein can be summarized as follows.

[0092] [1] A robot arm 3,300 includes a cylindrical first arm housing 31,331 extending in a predetermined forward / backward direction and having an opening 31a at an end on the forward / backward side in the forward / backward direction, a cylindrical second arm housing 32,332 extending in the forward / backward direction and accommodated in the first arm housing 31,331 so as to be movable forward / backward in the forward / backward direction through the opening 31a of the first arm housing 31,331, a first pulley holder 41,341 disposed in the first arm housing 31,331, a pair of first pulleys 45,345 supported by the first pulley holder 41,341, and a first belt 51,351 wound around the pair of first pulleys 45,345. 341 supports the pair of first pulleys 45, 345 so that the pair of first pulleys 45, 345 are aligned in the advancing / retreating direction, and is attached to the first arm housing 31, 331 so that the end 41a, 341a on the advancing side in the advancing / retreating direction is a free end, the second arm housing 32, 332 has an opening 32b at the end on the retreating side in the advancing / retreating direction, the free end of the first pulley holder 41, 341 is accommodated in the second arm housing 32, 332 through the opening 32b of the second arm housing 32, 332, and the first belt 51, 351 is connected to the second arm housing 32, 332 within the second arm housing 32, 332.

[0093] According to this configuration, the first pulley holder 41, 341, the pair of first pulleys 45, 345, and the first belts 51, 351, which are the forward and backward actuators, can be prevented from being exposed to the outside.

[0094] Specifically, the first pulley holder 41,341 is attached to the first arm housing 31,331 in a cantilevered manner within the first arm housing 31,331. This allows the first pulley holder 41,341 to be attached to the first arm housing 31,331 in a state where it has entered the second arm housing 32,332. By disposing the first pulley holder 41,341 at least partially within the second arm housing 32,332, the first belt 51,351 is also disposed at least partially within the second arm housing 32,332. By disposing the first belt 51,351 within the second arm housing 32,332, the connection between the first belt 51,351 and the second arm housing 32,332 can be easily realized. In other words, a configuration in which the second arm housing 32,332 advances and retreats with the movement of the first belt 51,351 can be easily realized. In this way, the first pulley holder 41, 341, the pair of first pulleys 45, 345 and the first belt 51, 351 are not exposed to the outside from the first arm housing 31, 331 and the second arm housing 32, 332, while the second arm housing 32, 332 can be moved forward and backward by the first belt 51, 351 etc.

[0095] [2] The robot arm 3,300 described in [1] further comprises a first sliding guide 35 arranged inside the first arm housing 31,331 and extending in the advance / retract direction, and a first sliding block 36 arranged on the outer surface of the second arm housing 32,332 and sliding against the first sliding guide 35 when the second arm housing 32,332 advances / retracts relative to the first arm housing 31,331.

[0096] According to this configuration, since the first sliding guide 35 and the first sliding block 36 are provided, the robot arm 3,300 can smoothly extend and retract. Furthermore, the relatively long first sliding guide 35 can be hidden inside the first arm housing 31,331.

[0097] [3] In the robot arm 3,300 described in [1] or [2], the first sliding block 36 is arranged in a portion of the second arm housing 32,332 which overlaps with the first arm housing 31,331 when the second arm housing 32,332 is fully extended from the first arm housing 31,331.

[0098] According to this configuration, the first sliding block 36 is also not exposed to the outside.

[0099] [4] In the robot arm 3,300 described in any one of [1] to [3], the first pulley holder 41,341 has a pair of plates 41p attached to the first arm housing 31,331 facing each other, and the pair of plates 41p support the pair of first pulleys 45,345 in a sandwiched state.

[0100] According to this configuration, the rigidity of the first pulley holder 41, 341 can be improved compared to a case where the first pulley holder 41, 341 has only one plate 41p, for example.

[0101] [5] In the robot arm 3,300 described in any one of [1] to [4], the first pulley holder 41,341 is attached to the first arm housing 31,331 via a first bracket 55.

[0102] According to this configuration, the first pulley holder 41, 341 can be attached to the first arm housing 31, 331 at a position other than the position of the first pulley holder 41, 341. Furthermore, the strength of the first arm housing 31, 331 can be increased by the first bracket 55.

[0103] [6] In the robot arm 3,300 described in any one of [1] to [5], the cross-sectional shape of the first arm housing 31,331 and the second arm housing 32,332 perpendicular to the advance / retreat direction is a closed cross-sectional shape having chamfered first corner portion 31c and second corner portion 32c, the first corner portion 31c of the first arm housing 31,331 faces the second corner portion 32c of the second arm housing 32,332, and the first bracket 55 is attached to the first corner portion 31c of the first arm housing 31,331.

[0104] According to this configuration, first corner portion 31c makes it easy to ensure a clearance between first arm housing 31,331 and second arm housing 32,332, so that first pulley holder 41,341 can be easily attached to first arm housing 31,331.

[0105] [7] The robot arm 3 according to any one of [1] to [6] further comprises a third arm housing 33 having a cylindrical shape extending in the advancing / retreating direction and accommodated in the second arm housing 32 so as to be movable forward and backward in the advancing / retreating direction through an opening 32a arranged at an end of the second arm housing 32 on the forward side in the advancing / retreating direction, a second pulley holder 42 arranged in the second arm housing 32, a pair of second pulleys 46 supported by the second pulley holder 42, and a second belt 52 wound around the pair of second pulleys 46, The pair of second pulleys 46 are supported so that the two pulleys 46 are aligned in the advancing / retreating direction, and are attached to the second arm housing 32 and the first belt 51 so that the end 42a on the advancing side in the advancing / retreating direction is a free end, the third arm housing 33 has an opening 33b at its retreating end in the advancing / retreating direction, the free end of the second pulley holder 42 is accommodated in the third arm housing 33 via the opening 33b of the third arm housing 33, and the second belt 52 is connected to the third arm housing 33 within the third arm housing 33.

[0106] According to this configuration, even when the robot arm 3 has three arm housings, the advance / retract actuator can be prevented from being exposed to the outside. Specifically, the second pulley holder 42 is attached to the second arm housing 32 in a cantilevered manner within the second arm housing 32. Furthermore, the second pulley holder 42 is connected to the first belt 51. That is, the connection between the first belt 51 and the second arm housing 32 is realized via the second pulley holder 42. As a result, when the first belt 51 rotates, the second arm housing 32 and the second pulley holder 42 advance and retract together. Furthermore, since the second pulley holder 42 is cantilevered, the second pulley holder 42 can be attached to the second arm housing 32 in a state in which it has entered the third arm housing 33. Since the second pulley holder 42 is at least partially disposed within the third arm housing 33, the second belt 52 is also at least partially disposed within the third arm housing 33. When the second pulley holder 42 advances and retreats in conjunction with the first belt 51, the second belt 52 advances and retreats integrally with the second pulley holder 42 while rotating. As a result, the third arm housing 33 also advances and retreats. In this way, the second pulley holder 42, the pair of second pulleys 46, and the second belt 52 are not exposed to the outside from the second arm housing 32 and the third arm housing 33, while the advance and retreat of the third arm housing 33 can be achieved by the second belt 52 etc. [Explanation of symbols]

[0107] 3,300 Robot Arms 31,331 First arm housing 31c 1st corner 32,332 Second arm housing 32c 2nd corner 35 First sliding guide (sliding guide) 36 First sliding block (sliding block) 41,341 First pulley holder 41p Plate 42,342 No. 2 pulley holder 45,345 No. 1 pulley 46 No. 2 pulley 51,351 First Belt 52 Second Belt 55 First bracket (bracket)

Claims

1. a cylindrical first arm housing extending in a predetermined forward / backward direction and having an opening at an end on the forward / backward side in the forward / backward direction; a second arm housing having a cylindrical shape extending in the advance / retract direction and accommodated in the first arm housing so as to be movable forward and backward in the advance / retract direction through the opening of the first arm housing; a first pulley holder disposed within the first arm housing; a pair of first pulleys supported by the first pulley holder; a first belt wound around the pair of first pulleys, the first pulley holder supports the pair of first pulleys so that the pair of first pulleys are aligned in the advancing / retreating direction, and is attached to the first arm housing so that an end portion on an advancing side in the advancing / retreating direction is a free end; the second arm housing has an opening at an end on a retreating side in the advance / retract direction, The free end of the first pulley holder is accommodated in the second arm housing through the opening of the second arm housing, The robotic arm, wherein the first belt is within and coupled to the second arm housing.

2. 2. The robot arm of claim 1, a slide guide disposed inside the first arm housing and extending in the forward / backward direction; a sliding block disposed on an outer surface of the second arm housing and sliding against the sliding guide when the second arm housing advances or retreats relative to the first arm housing.

3. 3. The robot arm of claim 2, The sliding block is disposed in a portion of a second arm housing that overlaps with the first arm housing when the second arm housing is fully extended from the first arm housing.

4. 2. The robot arm of claim 1, the first pulley holder has a pair of plates attached to the first arm housing in a state facing each other, The pair of plates supports the pair of first pulleys in a sandwiched state.

5. 2. The robot arm of claim 1, The first pulley holder is attached to the first arm housing via a bracket.

6. 6. The robot arm of claim 5, a cross-sectional shape of the first arm housing and the second arm housing perpendicular to the advancing / retreating direction is a closed cross-sectional shape having chamfered corners, the corner of the first arm housing faces the corner of the second arm housing, The bracket is attached to the corner of the first arm housing.

7. A robot arm according to any one of claims 1 to 6, a third arm housing having a cylindrical shape extending in the advancing / retreating direction and accommodated in the second arm housing so as to be movable forward and backward in the advancing / retreating direction through an opening disposed at an end of the second arm housing on an advancing side in the advancing / retreating direction; a second pulley holder disposed within the second arm housing; a pair of second pulleys supported by the second pulley holder; and a second belt wound around the pair of second pulleys. the second pulley holder supports the pair of second pulleys so that the pair of second pulleys are aligned in the advancing / retreating direction, and is attached to the second arm housing and the first belt so that an end portion on an advancing side in the advancing / retreating direction is a free end; the third arm housing has an opening at an end on a retreating side in the advance / retract direction, the free end of the second pulley holder is accommodated in the third arm housing through the opening of the third arm housing, The second belt is connected to the third arm housing within the third arm housing.

Images