Parallel Link Robot

Abstract

Provided is a parallel link robot including a base part, a movable member (3), and a plurality of arms that connect the base part and the movable member in parallel. Each of the arms includes: a drive link (10), (11), (12) that is rotationally driven by a motor installed in the base part; two parallel passive links (13), (14), (15) that couple the drive link and the movable member; ball joints (16) that are disposed between the drive link and the corresponding passive link and between the movable member and the corresponding passive link; and attachment mechanisms that attach the ball joints to the corresponding drive link or the movable member in a detachable manner. Each of the ball joints includes a ball (17) and a fixed part (18) that is provided integrally with the ball. At least one of the attachment mechanisms includes: a first screw hole (21) that is provided in the fixed part; a second through-hole (29), (32) that is provided in the drive link or the movable member; and a screw member (30) that is fastened to the first screw hole through the second through-hole.

Description

Technical Field

[0001] The present disclosure relates to a parallel link robot.

Background Art

[0002] There is known a parallel link robot including three arms that connect a base portion and a movable portion in parallel, each arm including a drive link driven by a motor and a pair of two parallel passive links that connect the drive link and the movable portion (see, for example, Patent Document 1). Between the drive link and the two passive links, and between the two passive links and the movable portion, they are rotatably connected by ball joints, respectively.

[0003] The two passive links of each arm are arranged at positions that sandwich the drive link and the movable portion from both side surfaces in the axial direction parallel to the rotation axis of the drive link. On both side surfaces of the drive link and the movable portion in the axial direction, screw holes are provided along the axial direction, and the ball joint is fixed by fastening a male screw fixed to the ball of the ball joint to the screw holes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To replace the ball joint, it is necessary to rotate the male screw to loosen the fastening with the screw hole, and the ball joint is moved along an axis parallel to the rotation axis of the drive link. For this reason, to remove the ball joint from the drive link or the movable portion, it is necessary to move it in a direction to widen the interval between the two passive links.

[0006] For the two passive links of each arm, in order to maintain the passive links in a parallel state regardless of high-speed operation, there may be provided support links that are stretched across the two passive links and rotatably attached to the passive links about an axis perpendicular to the longitudinal axis of the passive links. In this case, when replacing the ball joint, it is necessary to disassemble the support link from the passive link, which makes the work cumbersome. Therefore, it is desired that the ball joint can be replaced without moving the two passive links in the direction of widening the interval therebetween.

Means for Solving the Problem

[0007] One aspect of the present disclosure includes a base portion, a movable member disposed at an interval from the base portion, and a plurality of arms connecting the base portion and the movable member in parallel. Each of the arms includes a drive link that is rotationally driven by a motor installed on the base portion, two parallel passive links that connect the drive link and the movable member, ball joints disposed between each of the passive links and the drive link and between each of the passive links and the movable member, and a mounting mechanism that removably attaches each of the ball joints to the drive link or the movable member. Each of the ball joints includes a ball and a fixing portion integrally provided on the ball. At least one of the mounting mechanisms between each of the passive links and the drive link and between each of the passive links and the movable member of each of the arms includes a first screw hole or a first through hole provided in the fixing portion, a second through hole or a second screw hole provided in the drive link or the movable member, and a screw member that passes through the first through hole and is fastened to the second screw hole, or passes through the second through hole and is fastened to the first screw hole. 、By releasing the fastening of the screw member, the passive link to which the ball joint is attached and at least one of the corresponding drive link and the movable member can be separated along the longitudinal direction of the passive link. It is a parallel link robot.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] The parallel link robot 1 according to the first embodiment of the present disclosure will be described below with reference to the drawings. As shown in FIG. 1, the parallel link robot 1 according to the present embodiment includes a base portion 2 fixed to a ceiling or a gantry, a movable member 3 disposed at a distance below the base portion 2, and three arms 4, 5, 6 that connect the base portion 2 and the movable member 3 in parallel.

[0010] Three servo motors (motors) 7, 8, 9 for driving the three arms 4, 5, 6 respectively are installed on the base portion 2. Each of the arms 4, 5, and 6 includes drive links 10, 11, and 12 that are rotationally driven about a horizontal axis A by respective servo motors 7, 8, and 9, and two parallel bar-shaped passive links 13, 14, and 15 that connect the drive links 10, 11, and 12 to the movable member 3. The three drive links 10, 11, and 12 are arranged at equal intervals about a central axis B that extends vertically through the center of the base portion 2.

[0011] At both ends of each of the passive links 13, 14, and 15, ball joints 16 that rotatably connect the passive links 13, 14, and 15 to the drive links 10, 11, and 12 and the movable member 3 are attached as shown in FIG. 2. The ball joint 16 includes a ball stud 19 and a socket 20. The ball stud 19 includes a ball 17 and a round bar-shaped stud (fixed portion) 18 that extends radially outward from the outer surface of the ball 17. The socket 20 includes an inner spherical surface 16a that partially covers the outer peripheral surface of the ball 17 and supports the ball 17 so as to be movable about a center point. By rotating the ball 17 about the center point within the socket 20, the stud 18 can be tilted in an arbitrary inclination direction.

[0012] In the example shown in FIG. 2, sockets 20 are fixed to both ends of the passive links 13, 14, and 15, and the ball studs 19 are rotatably supported with respect to the passive links 13, 14, and 15 within a predetermined angular range centered on a direction orthogonal to the longitudinal axis of the passive links 13, 14, and 15. A screw hole (first screw hole) 21 is provided in the end face of the stud 18 along the axial direction of the stud 18.

[0013] Between the two passive links 13, 14, and 15 of each of the arms 4, 5, and 6, a support link 22 is spanned as shown in FIGS. 2 and 3. The support link 22 includes two support plates 23 that are arranged on both sides sandwiching the two passive links 13, 14, and 15 in the radial direction, and bearings 25 that rotatably attach each support plate 23 about an axis C orthogonal to the longitudinal axis of the passive links 13, 14, and 15 to a shaft 24 fixed to the passive links 13, 14, and 15. In the figure, reference numeral 26 denotes a spacer adjusted to an appropriate length to apply preload to the bearing 25, and reference numeral 27 denotes a bolt for attaching the spacer 26 between two support plates 23.

[0014] The support link 22 rotates with respect to the passive links 13, 14, 15 in response to the rotation of the two passive links 13, 14, 15 with respect to the drive links 10, 11, 12. Therefore, even if the passive links 13, 14, 15 are rotated with respect to the drive links 10, 11, 12 with rapid acceleration and deceleration, the two passive links 13, 14, 15 of each arm 4, 5, 6 can be maintained in parallel.

[0015] As shown in FIGS. 1 and 2, on each of the drive links 10, 11, 12, at the positions where the passive links 13, 14, 15 are attached, two plate-like attachment portions 28 extending along a plane orthogonal to the rotation axis A are provided at intervals in the direction of the rotation axis A. As shown in FIG. 2, each attachment portion 28 is provided with a through hole (second through hole) 29 extending coaxially and parallel to the rotation axis A. The distance between the outer surfaces of the two attachment portions 28 is set equal to the distance between the end faces of the ball studs 19 when the longitudinal axes of the ball studs 19 attached to the two passive links 13, 14, 15 are arranged in a straight line.

[0016] Each of the drive links 10, 11, 12 and the ball studs 19 attached to the passive links 13, 14, 15 are fixed by fastening a bolt member (threaded member) 30 that penetrates from the inner surface side through the through hole 29 of the attachment portion 28 of the drive link 10, 11, 12 to the threaded hole 21 of the ball stud 19. The bolt member 30 is provided with a fitting portion 30c that fits into the through hole 29 of the attachment portion 28 between the male thread 30a at one end and the head 30b at the other end. Thereby, the ball stud 19 can be fixed in a state of being positioned at the attachment portion 28 of the drive links 10, 11, 12.

[0017] As shown in FIG. 2, on the movable member 3, at positions where three sets of six (two of which are shown in FIG. 2) passive links 13, 14, 15 are attached, three sets of six (two of which are shown in FIG. 2) plate-like attachment portions 31 extending radially outward from the outer peripheral surface along a plane parallel to the central axis D are provided. The two attachment portions 31 of each set are arranged in parallel with a gap in the tangential direction around the central axis D, and each is provided with a through hole (second through hole) 32 extending coaxially in the tangential direction.

[0018] Also, the distance between the outer surfaces of the two attachment portions 31 is set equal to the distance between the end faces of the ball studs 19 when the longitudinal axes of the ball studs 19 attached to the two passive links 13, 14, 15 are arranged in a straight line. In the present embodiment, the attachment mechanism is constituted by a first screw hole 21 provided in the stud 18, second through holes 29, 32 provided in the attachment portions 28, 31 of the drive links 10, 11, 12 or the movable member 3, and a bolt member 30 that passes through the second through holes 29, 32 and is fastened to the first screw hole 21.

[0019] The movable member 3 and the ball studs 19 attached to the passive links 13, 14, 15 are fixed by fastening a bolt member 30 passed through the through hole 32 of the attachment portion 31 of the movable member 3 to the screw hole 21 of the ball stud 19. The bolt member 30 is provided with a fitting portion 30c that fits into the through hole 32 of the attachment portion 31 between the male screw 30a at one end and the head portion 30b at the other end. Thereby, the ball stud 19 can be fixed in a state positioned at the attachment portion 31 of the movable member 3.

[0020] The operation of the parallel link robot 1 according to the present embodiment configured as described above will be described below. According to the parallel link robot 1 according to the present embodiment, by driving the three servo motors 7, 8, 9 synchronously, the movable member 3 can be translated to a desired three-dimensional position while being held in a horizontal posture.

[0021] Since the parallel link robot 1 moves the movable member 3 at high speed, the drive links 10, 11, 12, the passive links 13, 14, 15, and the ball joints 16 that connect the passive links 13, 14, 15 and the movable member 3 are frequently rotated repeatedly. Therefore, it is necessary to periodically check the state of the ball joints 16 and perform maintenance such as replacement when they are worn or the like.

[0022] According to the present embodiment, in order to replace the ball joint 16 that connects the passive links 13, 14, 15 and the drive links 10, 11, 12, first, as shown in FIG. 4, the fastening of the bolt member 30 fastened to the screw holes 21 of the ball studs 19 of the ball joints 16 of the two passive links 13, 14, 15 is loosened, and the bolt member 30 is removed. When removing the bolt member 30, since the bolt member 30 is moved in the direction of being pulled out to the inner surface side of the attachment portion 28 of the drive links 10, 11, 12 and removed, the bolt member 30 can be removed without changing the interval between the balls 17 of the two ball studs 19.

[0023] After the bolt member 30 is pulled out from the through hole 29, as shown in FIG. 5, the drive links 10, 11, 12 and the passive links 13, 14, 15 are relatively moved in the direction of arrow A along the outer surface of the attachment portion 28, whereby the drive links 10, 11, 12 and the passive links 13, 14, 15 can be separated. Then, in a state separated from the drive links 10, 11, 12, the ball joint 16 can be easily removed from the end portions of the passive links 13, 14, 15 and can be replaced with a new ball joint 16.

[0024] Next, in the reverse procedure of the above, with the ball stud 19 arranged such that the longitudinal axes of the studs 18 of the new ball joints 16 attached to the two passive links 13, 14, 15 are arranged on the same axis, the attachment portions 28 of the drive links 10, 11, 12 are inserted between the end faces of the ball stud 19 in the direction of arrow B. Then, the male thread 30a of the bolt member 30 that penetrates the through holes 29 of the two attachment portions 28 is fastened to the threaded holes 21 of the two ball studs 19, respectively. Thereby, the replacement work of the ball stud 19 is completed.

[0025] Thus, according to the parallel link robot 1 according to the present embodiment, when replacing the ball joints 16 that connect the drive links 10, 11, 12 and the two passive links 13, 14, 15, it is not necessary to change the distance between the balls 17 of the two ball joints 16 to be replaced. The distance between the balls 17 of the two ball joints 16 that connect the drive links 10, 11, 12 and the two passive links 13, 14, 15 is fixed by the two ball joints 16 that connect the support link 22 and the movable member 3 and the two passive links 13, 14, 15. Since the distance between the balls 17 is not changed during replacement, the ball joint 16 can be replaced without involving major work such as disassembling the support link 22 or removing the connection between the movable member 3 and the passive links 13, 14, 15.

[0026] In particular, when the two support plates 23 constituting the support link 22 are firmly fixed by an adhesive, it is necessary to peel off the adhesion to disassemble the support link 22, and the work of disassembling the support link 22 becomes more difficult. According to the present embodiment, since the ball joint 16 is replaced without disassembling the support link 22, there is an advantage that the time required for the work can be significantly reduced.

[0027] Also, the ball interval of the ball joint 16 connecting the movable member 3 and the passive links 13, 14, 15 is fixed by the two ball joints 16 connecting the support link 22 and the drive links 10, 11, 12 and the two passive links 13, 14, 15. Therefore, even when replacing the ball joint 16 between the movable member 3 and the passive links 13, 14, 15, etc., it can be easily replaced, etc. without major work, in the same manner as the ball joint 16 between the drive links 10, 11, 12 and the passive links 13, 14, 15.

[0028] Further, according to the parallel link robot 1 according to the present embodiment, a pair of passive links 13, 14, 15, ball joints 16 attached to both ends of the passive links 13, 14, 15, and a support link 22 attached to the passive links 13, 14, 15 can be handled as a passive link unit (unit). That is, there is an advantage that it can be manufactured and managed as a passive link unit, and not only maintenance work but also assembly work can be facilitated.

[0029] In the present embodiment, in order to fix the ball stud 19 in a positioned state to the drive links 10, 11, 12 or the movable member 3, a fitting portion 30c of a bolt member 30 fastened to the screw hole 21 of the ball stud 19 is fitted into through holes 29, 32 of attachment portions 28, 31 provided in the drive links 10, 11, 12 or the movable member 3. Instead of this, as shown in FIG. 6, a pin hole 33 may be provided in the stud 18 of the ball stud 19 parallel to the screw hole 21, and a pin hole 34 may be provided in the attachment portions 28, 31 parallel to the through holes 29, 32. Thereby, in a state positioned by a pin 35 fitted into the pin hole 33 of the stud 18 and the pin hole 34 of the attachment portions 28, 31, a general bolt 30 having no fitting portion 30c that penetrates the through holes 29, 32 is fastened to the screw hole 21 of the stud 18, and the ball stud 19 can be fixed to the drive links 10, 11, 12 or the movable member 3.

[0030] Alternatively, instead of inserting the drive links 10, 11, 12 or the attachment portions 31 of the movable member 3 between the end faces of the studs 18, as shown in FIG. 7, the studs 18 may be configured in a flat plate shape, and the drive links 10, 11, 12 or the movable member 3 may be fixed in a state of being stacked in the plate thickness direction of the studs 18. In the example shown in the figure, the stud 18 is provided with a through hole (first through hole) 36 penetrating in the plate thickness direction and a pin hole 37 parallel to the through hole 36, and the drive links 10, 11, 12 are provided with a screw hole (second screw hole) 38 extending in the plate thickness direction and a pin hole 39 in a flat plate-shaped attachment portion 28 parallel to the rotation axis A.

[0031] Then, in a state of being positioned by a pin 40 fitted into the pin hole 37 of the stud 18 and the pin hole 39 of the attachment portion 28, a bolt 30 penetrating the through hole 36 is fastened to the screw hole 38 of the attachment portion 28, and the ball stud 19 can be fixed to the drive links 10, 11, 12 or the movable member 3. In this case, the first through hole 36 provided in the stud 18 which is a fixing portion, the second screw hole 38 provided in the attachment portions 28, 31 of the drive links 10, 11, 12 or the movable member 3, and the bolt member 30 penetrating the first through hole 36 and fastened to the second screw hole 38 constitute an attachment mechanism.

[0032] Also, although the parallel link robot 1 is provided with three arms 4, 5, 6, alternatively, it may be provided with any number of two or more arms. Also, the case where the ball joints 16 connecting the drive links 10, 11, 12 and the passive links 13, 14, 15 and the ball joints 16 connecting the movable member 3 and the passive links 13, 14, 15 have the same structure has been described, but the present invention is not limited thereto, and only one of them may be adopted.

[0033] In each of the above-described embodiments, the case where the stud 18 has a screw hole 21 or a through hole 36 has been shown. However, as shown in FIG. 8, a structure including a stud 18 having a male screw 41 and an adapter 43 having a screw hole 42 for fastening the male screw 41 of the stud 18 may be adopted. In this case, the stud 18 and the adapter 43 serve as a fixing portion, and it is sufficient if the adapter 43 is provided with a through hole (first through hole) 44 and a pin hole 45.

[0034] In each of the above embodiments, the studs 18 of the ball joints 16 attached to the respective passive links 13, 14, 15 are provided separately for each of the passive links 13, 14, 15. Instead of this, as shown in FIG. 9, as a pair of ball joints 16, a structure including two balls 17 and an integral stud (fixing portion) 46 that connects between the two balls 17 may be adopted. In this case, one or more through holes (first through holes) 47 or screw holes (first screw holes, not shown) and one or more pin holes 48 are provided in the stud 46. Also in this case, the passive link unit including the ball joint 16 can be removed from the drive links 10, 11, 12 and the movable member 3 without disassembling the support link 22.

[0035] Therefore, if a structure is adopted in which the socket 20 is removed in the longitudinal axis direction from the passive links 13, 14, 15 without rotating around the longitudinal axes of the passive links 13, 14, 15, it can be exchanged in the unit of an assembly of two ball joints 16 and a single stud 18. Alternatively, the ball joint 16 can be exchanged by exchanging the entire passive link unit.

Explanation of Reference Numerals

[0036] 1 Parallel Link Robot 2 Base Portion 3 Movable Member 4, 5, 6 Arms 7, 8, 9 Servo Motors (Motors) 10, 11, 12 Drive Links 13, 14, 15 Passive Links 16 Ball joint 17 Ball 18, 46 Stud (fixed part) 21 Screw hole (first screw hole) 22 Support link 29, 32 Through hole (second through hole) 30 Bolt member (screw member) 36, 44, 47 Through hole (first through hole) 38 Screw hole (second screw hole) 43 Adapter (fixed part) Axis C

Claims

1. A base part, a movable member arranged at an interval with respect to the base part, and a plurality of arms connecting the base part and the movable member in parallel, each of the arms including a drive link rotationally driven by a motor installed on the base part, two parallel passive links connecting the drive link and the movable member, ball joints arranged between each of the passive links and the drive link and between each of the passive links and the movable member, and an attachment mechanism for detachably attaching each of the ball joints to the drive link or the movable member, each of the ball joints including a ball and a fixing part integrally provided on the ball, at least one of the attachment mechanisms between each of the passive links and the drive link and between each of the passive links and the movable member of each of the arms including a first screw hole or a first through hole provided in the fixing part, a second through hole or a second screw hole provided in the drive link or the movable member, and a screw member that passes through the first through hole and is fastened to the second screw hole or passes through the second through hole and is fastened to the first screw hole, A parallel link robot in which by releasing the fastening of the screw member, at least one of the passive link to which the ball joint is attached and the corresponding drive link and the movable member can be separated along the longitudinal direction of the passive link.

2. The parallel link robot according to claim 1, wherein the fixing parts of the two ball joints arranged at least on one of the intervals between each of the passive links and the drive link and between each of the passive links and the movable member of each of the arms are integrally formed.

3. Each of the arms includes a support link spanning between the two passive links and connecting the two passive links, and the parallel link robot according to claim 1 or claim 2, wherein the support link is rotatably attached to each of the passive links about an axis orthogonal to the longitudinal axis of the passive link.

4. The parallel link robot according to claim 3, wherein the two passive links having the ball joints attached to both ends thereof are detachably attached to the drive link and the movable member as a unit connected by the support link.

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