COUPLING STRUCTURE AND PARALLEL ROBOT

Abstract

The coupling structure (10) comprises: a pair of fastening members (11a), (11b) supported on two link pieces (50a), (50b), each having a longitudinal axis (C) and moving parallel to each other, with a gap therebetween so that they can rotate about axes of rotation (D) perpendicular to a plane comprising the longitudinal axes (C) of both link pieces (50a), (50b); and a coupling mechanism (15) adjustably setting the distance between the pair of fastening members (11a), (11b).

Description

{Technical field}

[0001] The present disclosure relates to a coupling structure and a parallel robot. {Background}

[0002] As is well known, there is a coupling structure that couples two links (coupling links) of a parallel robot by interposing an elastic link therebetween, with the two links arranged parallel to each other (see, for example, Patent Literature 1). This coupling structure utilizes the elastic force of the elastic link to pull the links in directions in which the two links are moved toward each other.

[0003] Each of the two links is pivotally supported on a drive link (base link) by a ball joint. Because the links are pulled in the directions in which the two links are moved toward each other using the elastic force of the elastic link, rattling in the ball joints is prevented, even when the ball joints are worn due to age. {List of known publications}{Patent literature}

[0004] {PTL 1] Unexamined Japanese Patent Application, Publication No. 2014-168839 {Brief description of the invention}{Technical problem}

[0005] When an external force exceeding the elastic force of the elastic link acts on the coupling structure while the parallel robot is operating, it is conceivable that the distance between the two links will increase, thus causing the ball joints to disengage. To avoid such a situation, if the elastic force of the elastic link is set excessively high beyond a reasonable contact pressure of the ball joints, the service life of the ball joints will be shortened. Therefore, there is a need to eliminate rattling caused by aging without pulling the two links toward each other with excessive force, while operating the two links in parallel. {Solution to the problem}

[0006] One aspect of the present disclosure is a coupling structure comprising: a pair of fastening members supported on two link pieces, each having a longitudinal axis and moving parallel to each other, with a gap therebetween so that they can rotate about axes of rotation perpendicular to a plane including the longitudinal axes of both link pieces; and a coupling mechanism adjustably setting a distance between the pair of fastening members. {Brief description of the drawings} { Fig. 1] Fig. 1 is a front view schematically showing a parallel robot according to an embodiment of the present disclosure. { Fig. 2] Fig. 2 is a front view showing a fixed state of coupling structures in a pair of passive members of the Fig. 1 shows a schematic representation of the parallel robot. { Fig. 3] Fig. 3 is a partial cross-sectional view showing one of the Fig. 2 shows a schematic representation of the coupling structures shown. { Fig. 4] Fig. 4 is a perspective view showing the shape of one of the fastening members in one of the Fig. 2 shows the coupling structures. { Fig. 5] Fig. 5 is a partial cross-sectional view showing a disassembled state of one of the Fig. 2 shows the coupling structures. { Fig. 6] Fig. 6 is a partial cross-sectional view for explaining a fastening method of one of the Fig. 2 shown coupling structures. { Fig. 7] Fig. 7 is a partial cross-sectional view for explaining the fastening method of one of the Fig. 2 shown coupling structures. { Fig. 8] Fig. 8 is a partial cross-sectional view showing the attached state of one of the Fig. 2 shows the coupling structures. { Fig. 9] Fig. 9 is a partial cross-sectional view showing a first modification of one of the Fig. 2 shows the coupling structures. { Fig. 10] Fig. 10 is a partial cross-sectional view showing a second modification of one of the Fig. 2 shows the coupling structures. { Fig. 11] Fig. 11 is a partial cross-sectional view showing a third modification of one of the Fig. 2 shows the coupling structures. { Fig. 12] Fig. 12 is a partial cross-sectional view showing a fourth modification of one of the Fig. 2 shows the coupling structures. {Description of embodiments}

[0007] Hereinafter, a coupling structure 10 and a parallel robot 100 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0008] The parallel robot 100 according to this embodiment comprises, for example, as shown in Fig. 1, a base 20 fixed to and suspended from the ceiling or the like, and a movable portion 30 disposed below the base 20 with a gap therebetween. Furthermore, the parallel robot 100 includes three arms 40 that couple the base 20 and the movable portion 30.

[0009] The arms 40 include three drive links (arms) 45 supported on the base 20 so as to be rotatable about three horizontal axes A, respectively. Furthermore, each of the arms 40 includes two passive links (links) 50a and 50b that connect the drive link 45 and the movable portion 30 as a pair and that are parallel to each other.

[0010] Furthermore, the parallel robot 100 includes coupling structures 10 according to this embodiment of the present disclosure, wherein the coupling structures 10 bridge between each pair of passive links 50a and 50b at the upper end and the lower end thereof.

[0011] The base 20 includes three servomotors 60 for respectively driving the three drive link pieces 45. The servomotors 60 are arranged at equal intervals in a circumferential direction around an axis B passing through the center of the base 20 in a vertical direction and have rotary drive shafts (not shown) that are respectively rotated about the horizontal axes A. In addition, the respective servomotors 60 include decelerators 61 that decelerate the rotation of the rotary drive shafts.

[0012] Each of the drive link pieces 45 is connected at the basal end thereof to the rotary drive shaft of the corresponding servo motor 60 and is rotatable about the axis A with respect to the base 20. In addition, the passive links 50a and 50b are as shown in Fig. 1 and Fig. 2 are each connected to a distal end of each of the drive link pieces 45 by ball joints 70a and 70b.

[0013] The ball joints 70a and 70b include ball joint pins 71a and 71b, respectively, attached to the distal end of each of the drive link pieces 45 and sockets 51a and 51b, respectively, connected to the ball joint pins 71a and 71b.

[0014] The ball joint pins 71a and 71b comprise balls 72a and 72b, respectively, and columnar pins 73a and 73b, respectively, which extend radially outward from spherical outer surfaces of the balls 72a and 72b. End surfaces of the pins 73a and 73b are respectively fixed by screws 74 on both sides in the direction of the axis A (see Fig. 1) is fixed to the drive link piece 45 across the distal end of the drive link piece 45.

[0015] As in Fig. 2, the sockets 51a and 51b each form end portions on one side of the passive members 50a and 50b in the direction of the longitudinal axis C. The sockets 51a and 51b include spherical inner surfaces 52a and 52b, respectively, which cover approximately half the areas of the spherical outer surfaces of the balls 72a and 72b. Furthermore, thin resin layers (not shown) made of a resin material such as silicone are disposed in the spherical inner surfaces 52a and 52b, and the balls 72a and 72b are fitted therein and each supported to be rotatable about centers thereof.

[0016] Next, the coupling structure 10 according to this embodiment will be described.

[0017] The coupling structure 10 according to this embodiment includes a pair of fastening members 11a and 11b, each attached to pins 53p provided in the sockets 51a and 51b, and a coupling mechanism 15 that couples the fastening members 11a and 11b to each other.

[0018] In this embodiment, the three pairs of passive links 50a and 50b and the coupling structures 10 that couple the respective pairs of passive links 50a and 50b at the upper and lower ends thereof all have the same configuration. Therefore, the configuration of a coupling structure 10 that couples one end of one passive link to one end of the other passive link in the pair of passive links 50a and 50b will be described below as an example.

[0019] As in Fig. 3, each of the pins 53p is attached to the socket 51a or 51b so as to project along an axis (rotation axis) D orthogonal to a plane comprising the two longitudinal axes C, on either side of the plane. In the figure, the pin 53p includes a rim-like flange, is fitted from one direction into a hole extending through the socket 51a or 51b in a radial direction, and is positioned so that the flange abuts an outer surface of the socket 51a or 51b.

[0020] In addition, bushings 53a and 53b are respectively attached to the portions of the pins 53p projecting from the sockets 51a and 51b.

[0021] Each of the bushings 53a and 53b has a cylindrical shape in which a hollow bore 53h is formed. Furthermore, a groove 53d, which is recessed radially inward, is formed at a center in the axial direction on an outer peripheral surface of each of the bushings 53a and 53b over the entire circumference thereof.

[0022] By fitting the pins 53p into the hollow holes 53h, the bushings 53a and 53b are each supported by the pins 53p to be rotatable about the axes D.

[0023] In the figure, bushings 53a and 53b, which have the same shape, are used. Each of the bushings 53a and 53b includes a notch to prevent interference with the flange of the pin 53p. The flange is housed in the notch of the bushings 53a, 53b, and the notch of the other of the bushings 53a, 53b is hollow.

[0024] It is noted that in the case where the pins 53p are integrally fixed to the sockets 51a and 51b by welding or the like, the flanges of the pins 53p and the notches of the bushings 53a and 53b may be omitted.

[0025] In addition, according to the presentation in Fig. 2, the other end of each of the passive links 50a and 50b in the direction of the longitudinal axis C also has the same configuration as one end thereof. Specifically, each of the sockets 51a and 51b is also attached to the other end of each of the passive links 50a and 50b. Furthermore, the sockets 51a and 51b are connected such that the ball joint pins 71a and 71b attached to an outer peripheral surface of the movable portion 30 are interposed from outside the two ball joint pins in the direction of the axis A.

[0026] As in Fig. 3 and Fig. As shown in Fig. 4, the fastening member 11a includes a hook portion 12a and an external thread 16a fixed to the hook portion 12a. The hook portion 12a is formed by bending, into a generally U-shape, an elongated strip-shaped flat metal plate having a plate thickness corresponding to the groove width of the groove 53d of the bushing 53a. Two flat metal plates of the substantially U-shaped hook portion 12a, which extend substantially parallel to each other, are arranged with a gap therebetween, the size of the gap corresponding to the size of a distance W between the grooves 53d of the pair of bushings 53a mounted on both sides of the socket 51a in the direction of the axis D.

[0027] In addition, the two flat metal plates of the hook portion 12a, which extend substantially parallel to each other, are provided with two hooks 13a, which are respectively hooked to the grooves 53d of the pair of bushings 53a attached to the pan 51a.

[0028] The two hooks 13a are formed by respectively cutting out the two substantially parallel flat metal plates of the hook portion 12a in the plate thickness direction.

[0029] Specifically, the two hooks 13a each include elongated holes 13h extending in a length direction of the hook portion 12a. At one end of each of the elongated holes 13h in the longitudinal direction thereof, an inner peripheral surface 13i is formed, which has an inner diameter dimension corresponding to the outer diameter dimension of a groove bottom of the groove 53d of the bushing 53a. Furthermore, at the other end of the elongated hole 13h in the longitudinal direction thereof, an opening 13o is provided, which provides an opening into the elongated hole 13h on one side thereof in the width direction of the hook portion 12a. The opening 13o is formed to be larger than the outer diameter dimension of the groove 53d of the bushing 53a at the groove bottom.

[0030] The external thread 16a is formed as a right-hand thread and extends to the opposite direction from the hooks 13a parallel to the hooks 13a at a position between the hooks 13a on the two sides in the hook portion 12a.

[0031] The fastening member 11b, on the other hand, includes a hook portion 12b having the same shape as the hook portion 12a of the fastening member 11a. Furthermore, an external thread 16b is fixed at a position between the hooks 13b provided on the two sides of the hook portion 12b. The external thread 16b has the same outer diameter (nominal diameter) and the same pitch as the external thread 16a, differing only in the rotation direction of its thread portion. In other words, the external threads 16a and 16b are in a reverse thread relationship with each other.

[0032] As in Fig. 3 and Fig. 5, the coupling mechanism 15 comprises the external threads 16a and 16b included in the fastening members 11a and 11b, and a nut member 17 screwed onto the external threads 16a and 16b.

[0033] The nut member 17 is a cylindrical member having a through hole 17h along a central axis thereof. On an inner surface of the through hole 17h of the nut member 17, an internal thread 17a that engages with the external thread 16a and an internal thread 17b that engages with the external thread 16b are formed side by side in the central axis direction.

[0034] The internal thread 17a, which has a right-hand thread, is formed on one end side from the center of the nut member 17 in the central axis direction, and the internal thread 17b, which has a left-hand thread, is formed on the other end side from the center of the nut member 17 in the central axis direction. In other words, the internal threads 17a and 17b are each arranged adjacent to each other on the same axis and serve as reversible threads opening in opposite directions to each other.

[0035] In addition, a pair of flat portions which are parallel to each other and which serve as portions with which a tool such as a wrench is engaged are provided on an outer peripheral surface of the nut member 17 on both sides of the central axis thereof.

[0036] In addition, fixing nuts 18a and 18b engage the external threads 16a and 16b, respectively. The fixing nuts 18a and 18b may have equivalent shapes except that the two nuts are in reverse thread relationship to each other, and may be ordinary commercially available nuts.

[0037] The operation of the coupling structures 10 thus configured and the parallel robot 100 will be described below. However, a coupling structure 10 that bridges one end of one link and one end of the other link in the pair of links 50a and 50b will also be described below as an example, as above.

[0038] When assembling the parallel robot 100, it is assumed that a unit comprising the base 20, the three servo motors 60, the three decelerators 61 and the three drive link pieces 45 is ready for installation. First, as shown in Fig. 1 and Fig. 2, a pair of ball joint pins 71a, 71b are fixed to the distal end of a drive link 45 and the outer peripheral surface of the movable portion 30, respectively, with the screws 74.

[0039] Next, as shown in Fig. 2, the sockets 51a and 51b at one end of the pair of passive links 50a and 50b are brought close to the ball joint pins 71a and 71b at the distal end of the drive link 45 from the outside in the direction of the axis A. Then, the spherical inner surfaces 52a and 52b of the sockets 51a and 51b are fitted to the balls 72a and 72b of the ball joint pins 71a and 71b, respectively.

[0040] Similarly, the spherical inner surfaces 52a and 52b of the sockets 51a and 51b at the other end of the pair of passive links 50a and 50b are fitted to the balls 72a and 72b of the ball joint pins 71a and 71b attached to the movable portion 30.

[0041] Next, as shown in Fig. 5 the fixing nuts 18a and 18b are engaged with the external threads 16a and 16b, respectively, which are fixed to the fastening members 11a and 11b, respectively.

[0042] Next, as shown in Fig. 6, the external threads 16a and 16b are engaged with the internal threads 17a and 17b of the nut member 17, respectively, and thus the two fastening members 11a and 11b are coupled together by the nut member 17. In this case, the lengths in which the external threads 16a and 16b and the internal threads 17a and 17b engage with each other are adjusted so that a gap between the openings 13o of the fastening members 11a and 11b approximately corresponds to a gap between the two axes D.

[0043] In this state, the fastening members 11a and 11b, which are coupled by the nut member 17, are as shown in Fig. 6 at a position where the hooks 13a, 13b of each pair sandwich the pans 51a and 51b, respectively, in the direction of the axis D. Then, as shown in Fig. 7 ensure that the bushings 53a and 53b pass through the respective openings 13o of the fastening members 11a and 11b and the bushings 53a and 53b are each arranged in the elongated holes 13h.

[0044] Next, the flat portions on the outer peripheral surface of the nut member 17 are gripped by a tool or the like, and the nut member 17 is rotated in one direction about the central axis thereof. Accordingly, the length in which the external thread 16a and the internal thread 17a engage with each other and the length in which the external thread 16b and the internal thread 17b engage with each other simultaneously increase.

[0045] As a result, the distance between the fastening members 11a and 11b decreases, and as shown in Fig. 8, the inner peripheral surfaces 13i of the fastening members 11a and 11b come into close contact with the grooves 53d of the bushings 53a and 53b, respectively. Accordingly, pressure can be applied to the ball joints 70a and 70b between the passive members 50a and 50b and the drive member 45 by pulling the pair of passive members 50a and 50b toward each other.

[0046] Furthermore, for example, by measuring the torque applied to the tool when the nut member 17 is rotated, the rotation of the nut member 17 is stopped at the time when it is confirmed that a sufficient amount of pressure is applied to the ball joints 70a and 70b.

[0047] After the rotation of the nut member 17 has been stopped, as in Fig. 8, the fixing nuts 18a and 18b are each screwed on so that they are in close contact with the nut member 17. In other words, due to the double nut effect of the fixing nuts 18a and 18b, the position of the nut member 17 is fixed with respect to the external threads 16a and 16b. Thus, the assembly work is completed.

[0048] As described above, with the coupling structure 10 according to this embodiment, the two passive links 50a and 50b can be coupled in a state where the distance between the two links is adjusted to a sufficient distance. Accordingly, even when a large external force acts during operation of the parallel robot 100, it is possible to prevent the gap between the passive links 50a and 50b from increasing. Furthermore, it is possible to avoid a situation where the ball joints 70a and 70b between the passive links 50a and 50b and the drive link 45 are subjected to pressure exceeding the required level.

[0049] Thus, the wear of the resin layers between the cups 51a and 51b and the balls 72a and 72b is suppressed, and it is possible to extend the service life of the ball joints 70a and 70b.

[0050] In addition, there are cases where the resin layers of the ball joints 70a and 70b are worn out and their thickness decreases due to age.

[0051] In this case, the fixing nuts 18a and 18b are loosened, the nut member 17 is rotated around the central axis, and the lengths at which the external threads 16a and 16b and the internal threads 17a and 17b engage with each other increase. Consequently, it is possible to bring the fastening members 11a and 11b close to each other to an extent corresponding to the decrease in the resin layers due to their wear.

[0052] Thus, even if the distance between the two passive links 50a and 50b changes, it is possible to adjust the distance at which the two passive links 50a and 50b are coupled according to the change, and thus it is possible to prevent the occurrence of rattling in the ball joints 70a and 70b.

[0053] In other words, it is possible to prevent rattling in the ball joints 70a and 70b without disposing a coil spring between the pair of passive links 50a and 50b as has been conventionally done. Furthermore, since no coil spring is used, it is possible to improve the working efficiency when the parallel robot 100 is washed or dried after washing.

[0054] Furthermore, in this embodiment, the length of engagement between the male thread 16a and the female thread 17a and the length of engagement between the male thread 16b and the female thread 17b can be adjusted simultaneously simply by rotating the nut member 17 around the central axis in one direction. In other words, there is an advantage in that it is possible to adjust the distance between the passive members 50a and 50b simply by manipulating the nut member 17 once.

[0055] It is noted that in this embodiment, nuts having a general shape as shown in Fig. 2 as the fixing nuts 18a and 18b. Alternatively, as shown in Fig. 9 each of the fixing nuts 18a and 18b comprises an outer peripheral wall 18c projecting in the axial direction over the entire circumference of an outer zone edge portion.

[0056] In this case, in the state where the fixing nuts 18a and 18b are respectively in close contact with the two ends of the nut member 17, portions of the external threads 16a and 16b located further outside the nut member 17 in the axial direction are surrounded by the respective outer peripheral walls 18c. Accordingly, the external threads 16a and 16b are not exposed to the outside, and thus it is possible to prevent dust and moisture from adhering to the external threads 16a and 16b.

[0057] Further, in addition to such a feature, grooves (not shown) may be provided over the entire circumferences of outer peripheral surfaces of base portions of the external threads 16a and 16b at intermediate positions in the axial direction thereof, and O-rings 18o may be fitted into the grooves.

[0058] In this case, the outer diameters of the O-rings 18o are selected to be slightly larger than the inner diameters of the outer peripheral walls 18c. Accordingly, the O-rings 18o are brought into close contact with inner peripheral surfaces of the outer peripheral walls 18c covering the base portions of the external threads 16a and 16b, while the O-rings 18o are slightly squeezed over the entire circumferences thereof. Consequently, the gaps between the outer peripheral surfaces of the base portions of the external threads 16a and 16b and the inner peripheral surfaces of the outer peripheral walls 18c covering the portions are sealed. Accordingly, there is an advantage in that it is possible to more reliably protect the external threads 16a and 16b from external dust and moisture.

[0059] Furthermore, in this embodiment, each of the fastening members 11a and 11b is attached to the sockets 51a and 51b, respectively, by the pair of bushings 53a and 53b. Alternatively, as shown in Fig. 10 the fastening members 11a and 11b are attached to the pans 51a and 51b with bearings 11c fixed to the fastening members 11a and 11b.

[0060] In the case of Fig. In the example shown in FIG. 10, the fastening members 11a and 11b each include a pair of parallel plate-like first portions 11d, each having a thickness large enough to allow the bearings 11c to fit thereon. Furthermore, each of the fastening members 11a and 11b includes a second portion 11e that couples one end of one of the first portions 11d and one end of the other first portion 11d among the pair of first portions 11d. Furthermore, the pins 53p, each projecting from outer surfaces of the cups 51a and 51b on the two sides thereof in the direction of the axis D, are fitted to the bearings 11c, each fitted to the other end of each of the first portions 11d of the fastening members 11a and 11b.

[0061] In such a configuration, it is also possible to attach the fastening members 11a and 11b, which couple the passive members 50a and 50b to each other, to the sockets 51a and 51b so that they are rotatable about the axes D.

[0062] Furthermore, in this embodiment, the coupling mechanism 15 includes the external threads 16a and 16b fixed to the fastening members 11a and 11b, and the nut member 17 in which the internal threads 17a and 17b corresponding to the external threads 16a and 16b are formed.

[0063] Alternatively, the internal threads 17a and 17b may be formed in the fastening members 11a and 11b, respectively.

[0064] For example, as shown in Fig. 10, the second portions 11e of the fastening members 11a and 11b, which are connected to the sockets 51a and 51b so as to be rotatable about the axes D, each comprise a shaft portion 11f projecting to the other side. A right-hand internal thread 17a may be formed in the shaft portion 11f of the fastening member 11a, and a left-hand internal thread 17b may be formed in the shaft portion 11f of the fastening member 11b.

[0065] Furthermore, in this case, as the coupling mechanism 15, a screw member 19 having a right-hand external thread 16a and a left-hand external thread 16b, each arranged side by side on the same axis, may be used instead of the nut member 17. The screw member 19 may include, for example, a hexagonal columnar body portion 19c, and the external threads 16a and 16b may each extend outwardly along a central axis of the body portion 19c from the two ends thereof.

[0066] Accordingly, by engaging the external threads 16a and 16b of the screw member 19 with the internal threads 17a and 17b of the fastening members 11a and 11b, respectively, it is possible to couple the fastening members 11a and 11b such that the distance between the two members can be adjusted.

[0067] Furthermore, in this embodiment, one fixing member 11a or 11b is mounted so that the socket 51a or 51b is disposed therebetween in the direction of the axis D. Alternatively, two fixing members 11a or 11b may be mounted so that the socket 51a or 51b is disposed therebetween in the direction of the axis D.

[0068] For example, as shown in Fig. 11, a flat plate-like fastening member 11a or 11b is attached to the socket 51a or 51b on the two sides thereof in the direction of the axis D so as to be rotatable about the axis D. Furthermore, a right-hand internal thread 17a is formed at a distal end of the fastening member 11a, and a left-hand internal thread 17b is formed at a distal end of the fastening member 11b. Thus, all pairs of fastening members 11a and 11b are connected by the screw member 19, which is the same as in the Fig. 10 shown embodiment, coupled together.

[0069] Moreover, in this embodiment, the fixing members 11a sandwiching the cup 51a in the direction of the axis D may be integrally connected to each other by a connecting member 11j, and the fixing members 11b sandwiching the cup 51b in the direction of the axis D may also be integrally connected to each other by a connecting member 11j.

[0070] Furthermore, in this case, the fastening members 11a and 11b are coupled to each other by disposing the nut member 17 therebetween; however, alternatively, the nut member 17 may be omitted and the fastening members 11a and 11b may be directly connected to each other.

[0071] For example, the fastening member 11a can be arranged as shown in Fig.12 may comprise an external thread 16c extending towards the fastening member 11b, and the fastening member 11b may comprise a through-bore 17c through which the external thread 16c passes.

[0072] Specifically, in this case, the coupling mechanism 15 is composed of the external thread 16c of the fastening member 11a, the through hole 17c formed in the fastening member 11b, and the two coupling nuts (nut members) 18 engaged with the external thread 16c. Furthermore, in the state where the external threads 16c are passed through the through hole 17c, the two coupling nuts 18 are respectively screwed from two sides of the through hole 17c in the axial direction thereof.

[0073] Accordingly, the two coupling nuts 18 sandwich outer peripheral portions on the two sides of the through-hole 17c in the axial direction thereof, and the fastening members 11a and 11b are connected to each other. Furthermore, by adjusting the positions where the two coupling nuts 18 are screwed onto the external thread 16c, it is possible to change the length of the external thread 16c inserted into the through-hole 17c. Accordingly, as in the above-described case, it is possible to couple the passive members 50a and 50b to each other while adjusting the distance between the two members.

[0074] The embodiments of the present disclosure have been described in detail above; however, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, changes, partial omissions, etc. may be made to the embodiments insofar as the resulting embodiments do not deviate from the scope of the invention or from the concept and scope of the invention derived from the contents described in the claims and their equivalents. For example, in the embodiments described above, the order of the individual operations or the order of the individual operations is merely exemplary and does not constitute a limitation. {Reference symbol list} 10 Coupling structure 11a, 11b Fastening link 15 Coupling mechanism 16a, 16b, 16c external thread 17 Mother's member 17a, 17b internal thread 17c Through hole 18 Coupling nut (nut link) 18a, 18b Fixing nut 18c outer peripheral wall 19 screw link 20 substructure 30 movable section 45 Drive link (arm) 50a, 50b passive limb (limb) 100 parallel robots C Longitudinal axis D axis (rotation axis) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2014-168839

[0004]

Claims

[1] Coupling structure comprising: a pair of fastening members supported on two link pieces, each having a longitudinal axis and moving parallel to each other, with a gap therebetween so that they can rotate about axes of rotation perpendicular to a plane comprising the longitudinal axes of both link pieces; and a coupling mechanism that adjustably sets a distance between the pair of fastening links. [2] Coupling structure according to claim 1, wherein: the coupling mechanism comprises external threads fixed to the respective fastening members and a nut member having two internal threads which respectively engage with the two external threads; and the two external threads are arranged on the same axis and are in a reverse thread relationship to each other. [3] The coupling structure according to claim 2, further comprising two fixing nuts each screwed onto the external threads, wherein in a state where the distance between the fastening members is adjusted by the respective external threads and the respective internal threads, the two fixing nuts are screwed so as to be in close contact with the nut member. [4] The coupling structure according to claim 3, wherein each of the fixing nuts comprises an outer peripheral wall surrounding, on an opposite side of the nut member, the external thread screwed to the fixing nut. [5] Coupling structure according to claim 1, wherein: the coupling mechanism comprises internal threads formed in the respective fastening members and a screw member having two external threads which respectively engage with the two internal threads; and the two internal threads are arranged on the same axis and are in a reverse thread relationship to each other. [6] Coupling structure according to claim 1, wherein: the coupling mechanism comprises a through-hole provided in one of the fastening members, an external thread provided in another fastening member and extending through the through-hole, and a nut member screwed onto the external thread; and by adjusting a position at which the nut member is screwed onto the external thread extending through the through hole, the distance between the two fastening members is adjusted. [7] Parallel robot comprising: a substructure; a movable portion arranged separated from the base by a gap therebetween; several arms that are pivotally connected to the base; two pair of links coupling the arm and the movable portion and having longitudinal axes parallel to each other; and a coupling structure according to claim 1 provided between the pair of links.

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