Horizontal multi-joint robot

Abstract

The present invention provides a horizontal multi-joint robot that can prevent damage caused by brake collision and improve reliability. The horizontal multi-joint robot (1) comprises: a base (2); a first arm (3) which is rotatably supported on the base in the horizontal direction; a second arm (4) which is rotatably supported on the first arm in the horizontal direction; a shaft (5) which is linearly supported on the second arm along the long axis in the vertical direction; and a brake (6) which is mounted on the shaft and limits the vertical movement of the shaft within a movable range (S). The brake comprises: a fixing portion (61) which is fixed to the outer peripheral surface of the shaft and protrudes radially from the outer peripheral surface thereof; and a buffer portion (62) which is fixed to either the fixing portion or the second arm. The buffer portion is arranged at a position clamped by the fixing portion and the second arm in the vertical direction, and when the shaft attempts to move beyond the movable range, the buffer portion buffers the impact from the fixing portion to the second arm by deformation.

Description

Technical Field

[0001] The invention relates to a horizontal multi-joint robot, in particular to a brake structure of the horizontal multi-joint robot. Background Art

[0002] It has long been known that there is a horizontal multi-joint robot comprising a base, a first arm, a second arm and an axis, wherein the first arm is supported on the base in a manner capable of rotating in a horizontal direction, the second arm is supported on the first arm in a manner capable of rotating in a horizontal direction, and the axis is supported on the second arm in a manner capable of moving in a vertical direction and rotating around a vertical axis (for example, refer to patent document 1).

[0003] In addition, in a robot including a shaft that moves in a longitudinal direction, there is known a configuration in which movement of the shaft is restricted within a predetermined range by a brake fixed to an end of the shaft (for example, see Patent Documents 2 and 3).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 61-103792

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 3-35992

[0008] Patent Document 3: Japanese Patent Application Publication No. 2000-326278 Summary of the invention

[0009] Problems to be solved by the invention

[0010] A structure is known in which a brake is installed at the end of a shaft in a horizontal multi-joint robot to mechanically limit the range of movement of the shaft in the vertical direction relative to the second arm. Due to the collision between the brake and the second arm, the components of the second arm or the brake may be damaged. For example, an indentation caused by the impact may be formed on the components of the second arm, or the installation position of the brake on the shaft may be offset.

[0011] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a horizontal multi-joint robot that can prevent damage due to brake collision and can provide reliability.

[0012] Solutions for solving problems

[0013] In order to achieve the above-mentioned object, the present invention can provide the following solutions.

[0014] One embodiment of the present invention is a horizontal multi-joint robot, comprising: a base; a first arm, which is supported on the base in a manner that allows it to rotate in a horizontal direction; a second arm, which is supported on the first arm in a manner that allows it to rotate in a horizontal direction; an axis, which is supported on the second arm in a manner that allows it to move linearly along a long axis in a vertical direction; and a brake, which is mounted on the axis and limits the vertical movement of the axis within a movable range, the brake comprising: a fixing portion, which is fixed to the outer peripheral surface of the axis and protrudes radially from the outer peripheral surface of the axis; and a buffer portion, which is fixed to either the fixing portion or the second arm, the buffer portion being arranged at a position clamped in the vertical direction by the fixing portion and the second arm, and when the axis attempts to move beyond the movable range, the buffer portion buffers the impact from the fixing portion to the second arm by deformation.

[0015] According to this solution, the wrist at the lower end of the axis moves two-dimensionally in the horizontal direction by the rotation of the first arm and the second arm, and moves in the vertical direction by the linear movement of the axis.

[0016] In this case, when the shaft attempts to move beyond the movable range in the vertical direction, the fixed portion of the brake fixed to the shaft abuts against the second arm via the buffer portion, thereby limiting further movement of the shaft. At this time, the buffer portion clamped between the fixed portion and the second arm is deformed, thereby buffering the impact applied to the fixed portion and the second arm. The deformation of the buffer portion is, for example, elastic compression in the vertical direction or plastic deformation. In this way, damage to the brake and the second arm caused by the collision of the brake can be prevented, and reliability can be improved.

[0017] In the above solution, the buffer portion and the fixing portion may be integrated.

[0018] According to this structure, the fixing part is fixed to the shaft, thereby the buffer part is also mounted on the shaft. Therefore, a structure for mounting the buffer part on the shaft or the second arm is not required, and the number of parts and weight of the brake can be suppressed.

[0019] In the above aspect, the stopper is a single cylindrical member for covering the outer peripheral surface of the shaft, the fixing portion is one end of the member in the vertical direction, and the buffer portion is the other end of the member in the vertical direction.

[0020] According to this structure, the brake can be manufactured by processing it into a single component.

[0021] In the above aspect, a circumferential slit extending in the circumferential direction may be formed in the buffer portion.

[0022] According to this structure, the elastically compressible buffer portion can be manufactured by simple processing, which is particularly advantageous when the brake is made of a highly rigid material.

[0023] In the above solution, an axial slit extending in the vertical direction may be formed in the fixing portion.

[0024] According to this structure, by reducing the width of the axial slit, the inner diameter of the fixing portion can be reduced while maintaining the inner diameter of the buffer portion. Therefore, by reducing the inner diameter of the fixing portion, the fixing portion can be fixed to the shaft by friction. In addition, between the fixing portion and the buffer portion, only the fixing portion can be selectively fixed to the shaft.

[0025] Effects of the Invention

[0026] According to the present invention, it is possible to prevent damage due to brake collision and improve reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an overall structural diagram of a horizontal multi-joint robot according to an embodiment of the present invention.

[0028] Figure 2 It is a schematic structural diagram showing the supporting structure of the shaft inside the second arm.

[0029] Figure 3 yes Figure 1 A perspective view of the brake of a horizontal articulated robot.

[0030] Figure 4 yes Figure 3 Side view of the brake.

[0031] Figure 5 This is a diagram showing a state in which the upper stopper is in contact with the second arm.

[0032] Figure 6 It is a diagram showing a modified example of the arrangement of the buffer portion of the brake.

[0033] Figure 7 It is a perspective view of a modified example of the brake.

[0034] Figure 8 yes Figure 7 A three-dimensional view of the buffer portion of a brake.

[0035] Description of Reference Numerals

[0036] 1: Horizontal multi-joint robot

[0037] 2: Base

[0038] 3: First Arm

[0039] 4: Second Arm

[0040] 5: Axis

[0041] 6: Brake

[0042] 61: Fixed part

[0043] 61a: Slit (axial slit)

[0044] 61b: Bolt hole

[0045] 62, 63: Buffer

[0046] 62a: Slit (circumferential slit)

[0047] 9: Ball screw nut

[0048] 10: Ball spline nut

[0049] 11, 13: belt

[0050] 12, 14: Pulley

[0051] A, B, C: Axis DETAILED DESCRIPTION

[0052] A horizontal multi-joint robot according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0053] like Figure 1 As shown, the horizontal multi-joint robot 1 of this embodiment includes: a base 2 set on a setting surface; a first arm 3 supported by the base 2; a second arm 4 supported by the first arm 3; a shaft 5 supported by the second arm 4; and two brakes 6 set on the shaft 5.

[0054] Reference numeral 7 is a cable for connecting the base 2 and the control device (not shown), and reference numeral 8 is a cable for connecting the base 2 and the second arm 4. A control signal and power are supplied from the control device to the servo motor in the base 2 via the cable 7. In addition, a control signal and power are supplied to the servo motor in the second arm 4 via the cables 7 and 8.

[0055] One end of the first arm 3 is supported on the base 2 , and the first arm 3 is rotated about a first axis A in the vertical direction relative to the base 2 by a first servo motor (not shown).

[0056] One end of the second arm 4 is supported by the other end of the first arm 3 , and the second arm 4 is rotated relative to the first arm 3 about the second axis B by a second servo motor (not shown). The second axis B is parallel to the first axis A.

[0057] The shaft 5 vertically penetrates the other end of the second arm 4 and is supported by the second arm 4 so as to be linearly movable along a third axis C and rotatable about the third axis C. The third axis C is parallel to the first axis A and the second axis B and coincides with the long axis of the shaft 5 .

[0058] like Figure 2 As shown, inside the second arm 4, a ball screw nut 9 and a ball spline nut 10 are provided to respectively support the shaft 5. The ball screw nut 9 and the ball spline nut 10 are supported relative to the second arm 4 in a manner that they can rotate around the third axis C by means of bearings not shown. The rotation of a servo motor (not shown) for linear movement is transmitted to the ball screw nut 9 by means of a belt 11 and a pulley 12, so that the ball screw nut 9 rotates around the third axis C, thereby causing the shaft 5 to move along the third axis C and in the vertical direction. The rotation of a servo motor (not shown) for rotation is transmitted to the ball spline nut 10 by means of a belt 13 and a pulley 14, so that the ball spline nut 10 rotates around the third axis C, thereby causing the shaft 5 to rotate around the third axis C.

[0059] like Figure 3 and Figure 4 As shown, the brake 6 is a single cylindrical component having an inner diameter larger than the outer diameter of the shaft 5. The brake 6 is mounted on the outer peripheral surface of the shaft 5 and protrudes radially outward from the outer peripheral surface of the shaft 5. The brake 6 is manufactured by cutting a cylindrical metal component having high rigidity, for example. The brake 6 has a fixing portion 61 fixed to the shaft 5 and a buffer portion 62 that can be elastically compressed in the direction along the central axis.

[0060] The fixing portion 61 is one end portion of the brake 6 and is formed with a slit (axial slit) 61a. The slit 61a is formed along the direction of the central axis from one end face of the brake 6 and penetrates radially from the outer peripheral surface to the inner peripheral surface of the fixing portion 61. In addition, a bolt hole 61b orthogonal to the slit 61a is formed in the fixing portion 61. When the fixing portion 61 is arranged around the shaft 5, the bolt is tightened into the bolt hole 61b, thereby reducing the inner diameter of the fixing portion 61, so that the fixing portion 61 can be fixed to the shaft 5 by friction between the inner peripheral surface of the fixing portion 61 and the outer peripheral surface of the shaft 5.

[0061] The buffer portion 62 is the other end portion of the brake 6 and is formed with a slit (circumferential slit) 62a. The slit 62a extends in the circumferential direction of the buffer portion 62 and penetrates radially from the outer peripheral surface to the inner peripheral surface of the buffer portion 62. The slit 62a is, for example, spiral. The buffer portion 62 can be elastically compressed in the direction along the central axis of the brake 6 by reducing the width of the slit 62a. When the fixing portion 61 is fixed to the shaft 5 by bolts, the inner diameter of the fixing portion 61 is reduced as described above, but the inner diameter of the buffer portion 62 does not need to be reduced and is maintained. Therefore, in a state where the fixing portion 61 is fixed to the shaft 5, the buffer portion 62 can be extended and retracted in the direction of the third axis C.

[0062] In the present embodiment, the axial slit 61 a is connected to the circumferential slit 62 a , thereby reliably achieving the effect of selectively reducing the inner diameter of only the fixing portion 61 in the radial direction between the fixing portion 61 and the buffer portion 62 .

[0063] One brake 6 is fixed to the upper end of the shaft 5 in an orientation in which the fixing portion 61 is arranged on the upper side and the buffer portion 62 is arranged on the lower side. The other brake 6 is fixed to the lower end of the shaft 5 in an orientation in which the fixing portion 61 is arranged on the lower side and the buffer portion 62 is arranged on the upper side. Therefore, each buffer portion 62 is arranged at a position clamped in the vertical direction by the fixing portion 61 and the second arm 4. Reference numeral 5a is a wrist portion to which an end effector such as a hand is connected.

[0064] In this way, the movable range of the shaft 5 relative to the second arm 4 in the vertical direction is mechanically limited by the two brakes 6 provided on the upper and lower sides of the second arm 4. Specifically, the upper brake 6 abuts against the upper surface of the second arm 4, thereby limiting the further descent of the shaft 5. The lower brake 6 abuts against the lower surface of the second arm 4, thereby limiting the further rise of the shaft 5.

[0065] The control device provides control signals and power to each servo motor according to the action program, and controls the movement of the first arm 3, the second arm 4 and the shaft 5. Figure 1 As shown, a stroke range S of the shaft 5 in the vertical direction is set in the action program. The control device controls the movement of the shaft 5 in the vertical direction within the stroke range S.

[0066] Each stopper 6 is fixed to the shaft 5 at a position where the shaft 5 exceeds the boundaries S1 and S2 of the stroke range S and contacts the second arm 4. Therefore, as long as the shaft 5 moves within the stroke range S, the stopper 6 can be arranged at a position separated from the cover of the second arm 4 in the vertical direction.

[0067] Next, the operation of the horizontal articulated robot 1 having the above-described structure will be described.

[0068] According to the horizontal multi-joint robot 1 of the present embodiment, the position of the wrist 5a of the shaft 5 is changed two-dimensionally in the horizontal direction by the rotation of the first arm 3 around the first axis A and the rotation of the second arm 4 around the second axis B. In addition, the position of the wrist 5a is changed in the vertical up-down direction by the linear movement of the shaft 5 along the third axis C, and the posture of the wrist 5a is changed around the third axis C by the rotation of the shaft 5 around the third axis C.

[0069] Here, the movement of the shaft 5 in the vertical direction is controlled by the control device within the stroke range S set by the motion program. As long as the shaft 5 moves within the stroke range S, the brake 6 does not interfere with the second arm 4.

[0070] However, if the control device cannot properly limit the movement range of the shaft 5 due to an erroneous setting of the stroke range S of the operation program, the shaft 5 may move beyond the normal stroke range S. In this case, the movement of the shaft 5 is mechanically limited by the brake 6 .

[0071] Specifically, when the shaft 5 attempts to descend beyond the lower end S2 of the travel range S, as shown in FIG. Figure 5 As shown, the upper brake 6 abuts against the upper surface of the second arm 4, thereby preventing the shaft 5 from further descending. When the shaft 5 attempts to rise beyond the upper end S1 of the stroke range S, the lower brake 6 abuts against the lower surface of the second arm 4, thereby preventing the shaft 5 from further ascending.

[0072] The brake 6 is fixed to the shaft 5 due to the friction between the fixing portion 61 and the shaft 5. Therefore, when a strong impact is applied to the brake 6, the position of the brake 6 may be displaced or the brake 6 may fall off the shaft 5. In addition, when a strong impact is applied to the second arm 4, parts of the second arm 4 may be damaged. For example, when the brake 6 directly contacts the nuts 9 and 10, an indentation is formed on the rotating surface of the nuts 9 and 10 or the balls of the shaft 5, so that the nuts 9 and 10 cannot operate normally.

[0073] According to the present embodiment, when the brake 6 abuts against the second arm 4, the buffer portion 62 clamped between the fixing portion 61 and the second arm 4 is elastically compressed in the vertical direction, thereby absorbing the impact with the buffer portion 62, and buffering the impact applied to the fixing portion 61 and the second arm 4. Thus, it is possible to prevent the brake 6 from falling off the shaft 5 or the parts of the second arm 4 from being damaged, and to improve the reliability of the horizontal multi-joint robot 1.

[0074] In addition, the buffer portion 62 is integrated with the fixing portion 61, so a dedicated structure for mounting the buffer portion 62 on the shaft 5 is not required. By providing the buffer portion 62 on the brake 6, the increase in the installation space and weight of the brake 6 can be minimized. The installation space and weight of the brake 6 affect the motion performance of the shaft 5. According to this embodiment, the influence on the motion performance of the shaft 5 can be minimized.

[0075] When the buffer portion 62 and the fixing portion 61 are separate bodies, a complicated structure is required to support the buffer portion 62 on the shaft 5. This increases the number of parts and weight of the brake 6, and causes the operating performance of the shaft 5 to deteriorate.

[0076] In addition, the buffer portion 62 is made of a highly rigid material and is given elasticity by forming the slit 62a. The buffer portion 62 deforms only when a large vertical force is applied. That is, the buffer portion 62 does not deform unnecessarily during the movement of the shaft 5, especially during the horizontal movement.

[0077] In the present embodiment, the fixing portion 61 is fixed to the shaft 5 by bolt fastening, but the fixing portion 61 may be fixed to the shaft 5 by other means. For example, the fixing portion 61 may be fixed to the shaft 5 by welding. When the fixing portion 61 is fixed to the shaft 5 by means other than bolt fastening, the fixing portion 61 may be a member having a shape other than a cylindrical shape.

[0078] In the present embodiment, the stopper 6 is provided on both the upper side and the lower side of the second arm 4 , but the stopper 6 may be provided on only one of the upper side and the lower side of the second arm 4 .

[0079] In the present embodiment, the fixing portion 61 and the buffer portion 62 are formed of a single member, but instead, the fixing portion 61 and the buffer portion 62 formed of separate members may be fixed to each other.

[0080] According to this structure, different materials can be selected for the fixing portion 61 and the buffer portion 62 .

[0081] In this embodiment, the buffer portion 62 and the fixing portion 61 are integrated, but instead, the buffer portion 62 and the fixing portion 61 can also be separate. Figure 6 As shown, the buffer portion 62 of the upper stopper 6 may be fixed to the upper surface of the second arm 4 , and the buffer portion 62 of the lower stopper 6 may be fixed to the lower surface of the second arm 4 .

[0082] In the present embodiment, the buffer portion 62 is a cylindrical member in which the continuous spiral slit 62 a is formed. However, the buffer portion 62 may be another member that can be elastically compressed in the direction of the third axis C instead.

[0083] For example, the buffer portion 62 may be formed into a plurality of circumferential slits extending in the circumferential direction. Alternatively, the buffer portion 62 may be an elastic member such as a coil spring or rubber.

[0084] In the present embodiment, the upper brake 6 and the lower brake 6 are the same, but instead, the upper brake 6 and the lower brake 6 may be different.

[0085] When the upper stopper 6 collides with the second arm 4, the weight of the shaft 5 is also applied to the stopper 6, so the impact applied to the upper stopper 6 is greater than the impact applied to the lower stopper 6. Therefore, for example, the buffer portion 62 of the upper stopper 6 may be larger than the buffer portion 62 of the lower stopper 6, so that the upper stopper 6 has a higher buffering property than the lower stopper 6.

[0086] In the present embodiment, the buffer portion 62 utilizes elastic compression in the vertical direction to buffer the impact from the fixing portion 61 to the second arm 4 , but alternatively, the impact may be buffered by utilizing plastic deformation.

[0087] Figure 7 and Figure 8 An example of the plastically deformed buffer portion 63 is shown. The buffer portion 63 is integrated with the fixing portion 61 and is plastically deformed by collision with the second arm 4.

[0088] Figure 7 and Figure 8 The buffer portion 63 includes an annular plate-shaped end wall 63a opposite to the fixing portion 61, and a plurality of plate-shaped side walls 63b connecting the end wall 63a and the fixing portion 61. The end wall 63a is arranged in a direction perpendicular to the central axis of the fixing portion 61 at a position spaced apart from the fixing portion 61. The side wall 63b extends parallel to the central axis of the fixing portion 61 between the fixing portion 61 and the end wall 63a. The end wall 63a and the side wall 63b are respectively formed of thin metal plates, and the buffer portion 63 is manufactured, for example, by sheet metal processing, stamping or welding. Figure 7 and Figure 8 In the embodiment, the number of the side walls 63b is two, but may be three or more.

[0089] The brake 6 abuts against the second arm 4 at the end wall 63a and absorbs the impact by plastic deformation of the side wall 63b. In order to improve the impact absorption, an elastically compressed buffer portion 62 may be provided on the surface of the end wall 63a on the side opposite to the fixing portion 61 or between the fixing portion 61 and the buffer portion 63.

[0090] The buffer portion 63 may have a structure for promoting plastic deformation caused by collision with the second arm 4. For example, the buffer portion 63 may be configured to have a low rigidity portion having lower rigidity than other portions at an intermediate position between the fixing portion 61 and the end wall 63a, thereby buckling in the low rigidity portion.

[0091] The buffer portion 63 may also be mechanically fixed to the fixing portion 61 by means of the bolt 15. A bolt hole 63c for inserting the bolt 15 is formed at the end of the side wall 63b facing the fixing portion 61. In this case, the buffer portion 63 can be attached to and detached from the fixing portion 61, so that after the buffer portion 63 is damaged by the collision with the second arm 4, the damaged buffer portion 63 can be easily replaced with a new buffer portion 63.

Claims

1. A horizontal multi-joint robot, characterized in that: have: Pedestal; A first arm supported on the base in a manner capable of rotating in a horizontal direction; A second arm supported on the first arm in a manner capable of rotating in a horizontal direction; a shaft supported on the second arm in a manner capable of linear movement along a long axis in a vertical direction; as well as a brake having one end and the other end, and being mounted on the shaft to limit the vertical movement of the shaft within a movable range, The brake has: a fixing portion formed as the one end portion by processing a single member so as to be fixed to the outer peripheral surface of the shaft and to protrude in a radial direction from the outer peripheral surface of the shaft; and a buffer portion formed as the other end portion by processing the single member, The buffer portion is disposed at a position sandwiched by the fixing portion and the second arm in the vertical direction, and when the shaft attempts to move beyond the movable range, the buffer portion buffers an impact from the fixing portion to the second arm by deforming.

2. The horizontal multi-joint robot according to claim 1, characterized in that: The deformation of the buffer portion is elastic compression along the vertical direction.

3. The horizontal multi-joint robot according to claim 2, characterized in that: The buffer portion has a circumferential slit extending in the circumferential direction.

4. The horizontal multi-joint robot according to any one of claims 1 to 3, characterized in that: The fixing portion is formed with an axial slit extending in a vertical direction and a bolt hole orthogonal to the axial slit, and the fixing portion is fixed around the shaft by tightening a bolt into the bolt hole.

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