JP6396078B2 - Parallel link mechanism and link actuator - Google Patents

Description

  The present invention relates to a parallel link mechanism and a link actuating device that are used for devices that require a wide operating range with high speed and high accuracy, such as medical equipment and industrial equipment.

  Patent Documents 1 and 2 propose parallel link mechanisms used for various working devices such as medical equipment and industrial equipment.

JP 2000-94245 A US Pat. No. 5,893,296

  The parallel link mechanism of Patent Document 1 is relatively simple in configuration, but since the operating angle of each link is small, if the operating range of the traveling plate is set large, the link length becomes long, so that the dimensions of the entire mechanism are reduced. There is a problem that the size of the device increases and the size of the device increases. There is also a problem that the rigidity of the whole mechanism is low and the weight of the tool mounted on the traveling plate, that is, the weight of the traveling plate is limited to a small weight.

  The parallel link mechanism of Patent Document 2 has a configuration in which the distal end side link hub is connected to the proximal end side link hub through three or more sets of four-bar linkages so that the posture can be changed. Although it is compact, it can operate in a wide range of operation with high speed and high accuracy.

  However, the parallel link mechanism of Patent Document 2 has a problem that the component configuration is complicated and the assemblability is poor. In addition, in order to ensure rigidity and strength, each part has a complicated shape, and there is a problem that mass productivity is poor and manufacturing cost is high.

An object of the present invention is to provide a parallel link mechanism that can operate in a wide range of operation with high speed and high accuracy, is easy to assemble, is excellent in mass productivity, and can be manufactured at low cost.
Another object of the present invention is to provide a link actuating device capable of controlling an angle of two degrees of freedom and capable of accurately operating in a wide operating range and being manufactured at low cost. .

In the parallel link mechanism of the present invention, the link hub on the distal end side is connected to the link hub on the proximal end side so that the posture can be changed via three or more sets of link mechanisms. The end link member on the proximal end side and the distal end side that is rotatably connected to the link hub on the side and the distal end side link hub, and both ends on the other end of the end link member on the proximal end side and the distal end side A central link member rotatably connected to each other, and the central link member includes a first plate member having two or more bent portions in the plate thickness direction, and a bent portion in the plate thickness direction than the first plate member. And a second plate member having a small number of the first plate member and the second plate member .

  In this specification, “base end side” and “tip end side” are used in the following meanings. That is, the point at which the central axis of each rotational pair of the link hub and the end link member and the rotational pair of the end link member and the central link member intersect is called the “spherical link center” of the link hub. When a straight line that passes through the center of the link and intersects with the central axis of the rotation pair of the link hub and the end link member at right angles is referred to as a "link hub central axis", each link hub from the link hub to the proximal end side and the distal end side The spherical link center direction on the base end side when viewed from the intersection where the central axes intersect is the base end side, and the spherical link center direction on the front end side is the front end side.

  According to this configuration, the proximal-side link hub, the distal-side link hub, and the three or more sets of link mechanisms rotate the distal-side link hub around two orthogonal axes with respect to the proximal-side link hub. A free two-degree-of-freedom mechanism is configured. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub on the distal end side can be widened. For example, the maximum bend angle between the central axis of the link hub on the proximal end side and the central axis of the link hub on the distal end side is about ± 90 °, and the turning angle of the link hub on the distal end side with respect to the link hub on the proximal end side is 0 ° It can be set in the range of ~ 360 °.

Since the central link member is a plate material, the central link member can be manufactured at a low cost and is excellent in mass productivity. Further, when the central link member is a plate material, the configuration of the rotating pair of the end link member and the central link member can be simplified, and the assemblability is improved. In this parallel link mechanism, the central link member has a curved shape with an intermediate portion protruding inward for mechanical reasons. If the central link member has two or more bent portions, the amount of protrusion of the central link member to the inside of the intermediate portion can be reduced. Thereby, it is possible to avoid interference between the link mechanisms and interference with a device attached to the link hub on the proximal end side or the distal end side, and a substantially effective movable range in the movable range on the mechanism. Can be taken widely.
Moreover, since the central link member is composed of two plate members, the plate thickness of the plate member can be reduced while ensuring the strength of the central link member. Thereby, the central link member can be manufactured at a low cost and the weight can be reduced.
As described above, the central link member includes a first plate member having two or more bent portions in the plate thickness direction, and a second plate member having a smaller number of bent portions in the plate thickness direction than the first plate member. In this case, in accordance with the curved shape of the central link member, the first plate member having a large number of bent portions is arranged on the inner peripheral side of the curved portion, and the second number of bent portions is small. You may arrange | position a board | plate material to the outer peripheral side of a curve.

In the present invention, the plate member constituting the central link member is a metal plate, and the bent portion is preferably formed by sheet metal bending.
In this case, the bending portion can be easily processed.

In the above-described configuration, the end link member including the bearing is disposed between the first plate member and the second plate member in the rotating pair of the end link member and the central link member, When a rotation shaft is inserted into a through hole provided in each of the plate material and the second plate material and an inner ring of the bearing, and the first plate material and the second plate material, the inner ring of the bearing and the rotation shaft are fixed to each other. good.
According to this configuration, the first plate member and the second plate member support both ends of the rotating shaft, and the bearing is positioned between the two plate members. For this reason, the rigidity with respect to the moment load of the rotation couple of the end link member and the center link member is increased, and the rigidity of the entire parallel link mechanism is improved.

The said structure WHEREIN: The said through-hole provided in one board | plate material of a said 1st board | plate material and a 2nd board | plate material is a tight hole which does not produce a clearance gap between the said rotating shaft penetrated by this through-hole. And the said through-hole provided in the other board | plate material is good to use as the loose hole which a clearance gap produces between the said rotating shafts penetrated by this through-hole.
The two rotation shafts connected to both ends of the central link member have an angle with each other. For this reason, if the through hole of the plate material is a tight hole, the two rotary shafts and the two through holes can be aligned with each other, and then the rotary shaft can be advanced to insert the rotary shaft into the through hole. However, the rotating shaft cannot be inserted into the through hole by moving the plate material with respect to the two rotating shafts whose positions are fixed.
As in the above configuration, when the through holes of the two plate members are respectively a tight hole and a loose hole, assembly can be performed by the following procedure. That is, first, the two rotating shafts are aligned with a plate material having a through hole which is a tight hole, and the two rotating shafts are advanced while the plate material is fixed in position, thereby inserting the rotating shafts into the through holes. . Thereafter, the plate having a through hole which is a loose hole is moved with respect to the two rotational shafts whose positions are fixed, and the rotational shaft is inserted into the through hole while aligning the rotational shaft and the through hole. If the through hole is a loose hole, there is no need to accurately align the rotary shaft and the through hole, and the rotary shaft can be inserted into the through hole while shifting or tilting the plate material. Good sex. Since the rotating shaft is inserted through the through hole, which is a tight hole in one plate material, the assembly accuracy of the connecting portion between the central link member and the rotating shaft can be ensured.

In the link actuating device of the present invention, the posture of the distal end side link hub with respect to the proximal end side link hub can be arbitrarily set to two or more sets of the three or more sets of link mechanisms in the parallel link mechanism. A posture changing actuator for changing is provided.
If two or more sets of three or more sets of link mechanisms are provided with attitude change actuators, the attitude of the distal link hub relative to the proximal link hub can be determined. Thereby, the link actuator which can control the angle of 2 degrees of freedom is realizable at low cost.

In the parallel link mechanism of the present invention, the link hub on the distal end side is connected to the link hub on the proximal end side so that the posture can be changed via three or more sets of link mechanisms. The end link member on the proximal end side and the distal end side that is rotatably connected to the link hub on the side and the distal end side link hub, and both ends on the other end of the end link member on the proximal end side and the distal end side A central link member rotatably connected to each other, and the central link member includes a first plate member having two or more bent portions in the plate thickness direction, and a bent portion in the plate thickness direction than the first plate member. Since the second plate member with a small number of the first plate member and the second plate member is provided , it is possible to operate in a wide range of operation with high speed and high accuracy, easy to assemble, excellent in mass productivity, and inexpensive to manufacture.

  In the link actuating device of the present invention, the posture of the distal end side link hub with respect to the proximal end side link hub can be arbitrarily set to two or more sets of the three or more sets of link mechanisms in the parallel link mechanism. Since the posture changing actuator to be changed is provided, the angle of two degrees of freedom can be controlled, the operation in a wide operation range can be performed with high accuracy, and the actuator can be manufactured at low cost.

It is a perspective view of one state of the parallel link mechanism concerning the example of a proposal used as the foundation of this invention. It is the front view which abbreviate | omitted a part of the parallel link mechanism. It is sectional drawing of the link hub of the base end side of the parallel link mechanism, the edge part link member of a base end side, and a center link member. It is the figure which expressed one link mechanism of the parallel link mechanism with a straight line. (A) is the front view which abbreviate | omitted one part which shows the one use state of the parallel link mechanism, (B) is the front view which abbreviate | omitted a part which shows one use state of the comparative example with respect to the parallel link mechanism. It is a perspective view of one state of the parallel link mechanism concerning other examples of a proposal . It is the front view which abbreviate | omitted a part of the parallel link mechanism. It is sectional drawing of the link hub of the base end side of the parallel link mechanism, the edge part link member of a base end side, and a center link member. It is the front view which abbreviate | omitted a part of parallel link mechanism concerning one Embodiment of this invention. It is sectional drawing of the link hub of the base end side of the parallel link mechanism, the edge part link member of a base end side, and a center link member. (A), (B) is the fragmentary figure of the 1st board | plate material and 2nd board | plate material which comprise the center link member of the parallel link mechanism. It is the front view which abbreviate | omitted a part of parallel link mechanism concerning further different embodiment of this invention. It is sectional drawing of the link hub of the base end side of the parallel link mechanism, the edge part link member of a base end side, and a center link member. It is the front view which abbreviate | omitted some link actuating devices using the parallel link mechanism of FIGS. It is a partially broken top view which shows the link hub of the base end side of the same link actuator, the end part link member of a base end side, a drive mechanism part, etc. It is the front view which abbreviate | omitted some link actuating devices using the parallel link mechanism of FIG. 12, FIG.

A parallel link mechanism according to a proposed example as the basis of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing one state of the parallel link mechanism, and FIG. 2 is a front view in which a part of the parallel link mechanism is omitted. The parallel link mechanism 1 is configured such that a distal end side link hub 3 is connected to a proximal end side link hub 2 via three sets of link mechanisms 4 so that the posture can be changed. In FIG. 2, only one set of link mechanisms 4 is shown. The number of link mechanisms 4 may be four or more.

  Each link mechanism 4 includes a base end side end link member 5, a front end side end link member 6, and a central link member 7, and forms a four-joint link mechanism composed of four rotating pairs. The end link members 5 and 6 on the proximal end side and the distal end side are curved at a predetermined angle, and one ends thereof are rotatably connected to the link hub 2 on the proximal end side and the link hub 3 on the distal end side, respectively. ing. The center link member 7 is rotatably connected to both ends of the end link members 5 and 6 on the proximal end side and the distal end side, respectively. The three sets of link mechanisms 4 have the same geometric shape.

Further, as shown in FIG. 4, the model in which the link mechanism 4 is expressed by a straight line has a shape in which the proximal end portion and the distal end portion are symmetrical with respect to the central portion of the central link member 7. More specifically, a geometric model in which each link member 5, 6, 7 is expressed by a straight line, that is, a model expressed by each rotation pair and a straight line connecting these rotation pairs, is based on the center of the central link member 7. The end portion and the tip end portion are symmetrical. FIG. 4 represents only one set of link mechanisms 4 by straight lines. The parallel link mechanism 1 of the proposed example is a rotationally symmetric type, and includes a base end side link hub 2 and a base end side end link member 5, a front end side link hub 3 and a front end side end link member 6. The positional relationship is such that it is rotationally symmetric with respect to the center line C of the central link member 7.

  The parallel link mechanism 1 has a structure in which two spherical link mechanisms are combined, and each rotation pair of the link hubs 2 and 3 and the end link members 5 and 6, and the end link members 5 and 6 and the central link member. The center axis of each rotation pair 7 intersects with the spherical link centers PA and PB (FIG. 2) on the proximal end side and the distal end side. In addition, on the proximal end side and the distal end side, the distances from the rotary pairs of the link hubs 2 and 3 and the end link members 5 and 6 and the respective spherical link centers PA and PB are the same. The distances from the rotary pairs of 6 and the central link member 7 and the spherical link centers PA and PB are also the same. The central axis of each rotational pair of the end link members 5 and 6 and the central link member 7 may have a certain crossing angle γ or may be parallel.

  FIG. 3 is a cross-sectional view of the link hub 2 on the base end side, the end link member 5 on the base end side, and the central link member 7, and shows the rotational pair of the link hub 2 and the end link member 5. The relationship between the central axis O1, the central axis O2 of the rotation pair of the end link member 5 and the central link member 7, and the spherical link center PA is shown. The shapes and positional relationships of the distal end side link hub 3 and the distal end side end link member 6 are also the same as in FIG. 3 (not shown). In the illustrated example, the angle α formed by the central axis O1 of each rotational pair of the link hub 2 and the end link member 5 and the central axis O2 of each rotational pair of the end link member 5 and the central link member 7 is Although the angle is 90 °, the angle α may be other than 90 °.

  With the link hub 2 on the proximal end side, the link hub 3 on the distal end side, and the three sets of link mechanisms 4, the link hub 3 on the distal end side is rotatable about two orthogonal axes with respect to the link hub 2 on the proximal end side. A degree mechanism is configured. In other words, it is a mechanism that can freely change the posture of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side with two degrees of freedom of rotation. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side can be widened.

  For example, a straight line that passes through the spherical link centers PA and PB and intersects with the central axis O1 (FIG. 3) of each rotation pair of the link hubs 2 and 3 and the end link members 5 and 6 at right angles is the central axis of the link hubs 2 and 3. In the case of QA and QB (hereinafter referred to as “link hub central axis”), the maximum value of the bending angle θ (FIG. 1) between the link hub central axis QA on the proximal end side and the link hub central axis QB on the distal end side is approximately It can be ± 90 °. Further, the turning angle φ (FIG. 1) of the distal end side link hub 3 with respect to the proximal end side link hub 2 can be set in a range of 0 ° to 360 °. The bending angle θ is a vertical angle at which the distal end side link hub central axis QB is inclined with respect to the proximal end side link hub central axis QA, and the turning angle φ is relative to the proximal end side link hub central axis QA. On the other hand, it is a horizontal angle at which the link hub central axis QB on the front end side is inclined.

  The posture change of the distal end side link hub 3 with respect to the proximal end side link hub 2 is performed with the posture change center O that is the intersection of the proximal end side link hub central axis QA and the distal end side link hub central axis QB as the rotation center. Is called. The perspective view of FIG. 1 shows a state where the link hub central axis QB on the distal end side takes a certain operating angle with respect to the link hub central axis QA on the proximal end side, and the front view of FIG. The link hub central axis QA and the distal end side link hub central axis QB are on the same line. Even if the posture changes, the distance D (FIG. 2) between the spherical link centers PA and PB on the base end side and the tip end side does not change.

  In this parallel link mechanism 1, the angle of the central axis O1 of the rotation pair of the link hubs 2 and 3 and the end link members 5 and 6 in each link mechanism 4 and the length from the spherical link centers PA and PB are equal to each other, and The center axis O1 of the rotation pair of the link hubs 2 and 3 and the end link members 5 and 6 of each link mechanism 4 and the center axis O2 of the rotation pair of the end link members 5 and 6 and the center link 7 are the base ends. The end link member 5 on the proximal end side and the end link member 6 on the distal end side are equal in geometrical shape, intersecting the spherical link centers PA and PB on the side and the distal end side, and the central link member 7 is also based on When the shape is the same at the distal end side of the end side, the angular positional relationship between the central link member 7 and the end link members 5 and 6 is the same at the proximal end side and the distal end side with respect to the symmetry plane of the central link member 7. If so, geometric symmetry And a end link member 5 of the base end side link hub 2 and the proximal side, moving the same to the end link member 6 in the distal end side link hub 3 and the distal end side.

  Next, four rotation pairs of each link mechanism 4, that is, a rotation pair of the base end side link hub 2 and the base end side end link member 5, a front end side link hub 3 and a front end side end The structure of the rotation pair of the link member 6, the rotation pair of the end link member 5 and the central link member 7 on the proximal end side, and the rotation pair of the end link member 6 and the central link member 7 on the distal end side will be described. . Since the rotation pair corresponding to the proximal end side and the distal end side have the same structure, here, together with FIG. 3, the rotation pair portion of the link hub 2 on the proximal end side and the end link member 5 on the proximal end side, and The rotation pair of the end link member 5 and the center link member 7 on the base end side will be described.

  A shaft portion 11 is formed at three locations in the circumferential direction of the link hub 2, and inner rings (not shown) of two bearings 12 are fitted to the outer periphery of the shaft portion 11, and the base end of the end link member 5 is fitted. An outer ring (not shown) of the bearing 12 is fitted to the inner periphery of the formed bearing installation hole 13. That is, as for the bearing 12, the inner ring is fixed and the outer ring rotates. The bearing 12 is a ball bearing such as a deep groove ball bearing or an angular ball bearing, for example, and the shaft portion in a state where a predetermined preload is applied by tightening with a nut 15 screwed to the screw portion 11a of the shaft portion 11. 11 is fixed. A spacer 16 is interposed between the bearing 12 and the nut 15.

  Further, a shaft member 21 is fixedly provided at an end portion of the central link member 7, and inner rings (not shown) of two bearings 22 are fitted to the outer periphery of the shaft member 21, and the end of the end link member 5 is fitted. An outer ring (not shown) of the bearing 22 is fitted to the inner periphery of the bearing installation hole 23 provided in The shaft member 21 is inserted into the shaft insertion hole 24 of the central link member 7 by press fitting or the like. The bearing 22 is, for example, a ball bearing such as a deep groove ball bearing or an angular ball bearing, and the shaft member in a state where a predetermined preload is applied by tightening with a nut 25 screwed onto the screw portion 21a of the shaft member 21. 21 is fixed. Spacers 26 and 27 are interposed between the bearing 22 and the central link member 7 and between the bearing 22 and the nut 25, respectively.

  As described above, the structure in which the bearings 12 and 22 are provided in the respective rotating pair portions can reduce the rotational resistance by suppressing the frictional resistance in each rotating pair, and can ensure smooth power transmission. Durability can be improved. In the structure in which the bearings 12 and 22 are provided, by applying a preload to the bearings 12 and 22, the radial gap and the thrust gap can be eliminated, and shakiness of the rotation pair can be suppressed. The rotational phase difference between the link hub 3 side on the side and the distal end side is eliminated, and the constant velocity can be maintained and the occurrence of vibration and abnormal noise can be suppressed. In particular, by setting the bearing clearance between the bearings 12 and 22 to be a negative clearance, backlash generated between input and output can be reduced.

  The central link member 7 is composed of a single elongated metal plate having a constant thickness and a constant width and both ends formed in a semicircular shape. The metal plate is bent in the plate thickness direction at two bent portions 7a, and between the both ends. Is a curved shape having a predetermined angle γ. This curved shape is a shape in which the central portion protrudes to the inside of the parallel link mechanism 1, that is, the side close to the posture change center O (FIGS. 1 and 2). The bent portion 7a is bent by sheet metal bending. The shaft insertion holes 24 are provided at both ends of the central link member 7 made of a metal plate.

  Thus, when the center link member 7 is a plate material, the center link member 7 can be manufactured at low cost and mass productivity is good. Moreover, when the center link member 7 is a plate material, the configuration of the rotating pair of the end link members 5 and 6 and the center link member 7 can be simplified, and the assemblability is improved. In particular, when the plate material constituting the central link member 7 is a metal plate, the contour shape can be cut out, the bent portion 7a can be bent, and the shaft insertion hole 24 can be formed by sheet metal processing, which is easy to process.

  For reasons of the mechanism of the parallel link mechanism 1, the central link member 7 has a curved shape with an intermediate portion protruding inward. When the central link member 7 has two bent portions 7a, the amount of protrusion of the central link member 7 to the inside of the intermediate portion can be reduced as compared with the case where the bent portion 7a is one. As a result, interference between the link mechanisms 4 and interference with the equipment mounted on the link hubs 2 and 3 can be avoided, and the movable range on the mechanism (for example, the bending angle θ is 90 °, the turning angle φ Is substantially effective in the range of 360 °.

  FIG. 5 shows the front end side of the parallel link mechanism 1 (FIG. (A)) having two bent portions 7a of the central link member 7 and the parallel link mechanism 1 ′ (FIG. (B)) having one bent portion. It is the figure which compared the case where it mounts | wears to the link hub 3 with the end effector 100 projected in the base end side. Even if the posture of the link hub 3 on the distal end side is changed by the same angle with respect to the link hub 2 on the proximal end side, the end effector 100 is centered as shown in FIG. Interference with the link member 7 can be avoided (a circled portion), but when the bending portion 7a is at one place, the end effector 100 interferes with the central link member 7 as shown in FIG. You can see that it is a circle. Note that the number of the bent portions 7a may be three or more.

6 to 8 show other proposal examples . The parallel link mechanism 1 also, as in the proposed example, and posture changing linked via a link hub 3 three sets of link mechanisms 4 of the distal end side to the proximal end side link hub 2. The positional relationship and operational characteristics of each part are the same as those in the proposed example . Hereinafter, differences from the proposed example will be described.

  In FIG. 6, the link hubs 2 and 3 have donut shapes in which through holes 30 </ b> A and 30 </ b> B are formed at the center portions along the directions of the link hub central axes QA and QB, respectively. The centers of the through holes 30A and 30B coincide with the link hub central axes QA and QB. The end link members 5 and 6 are rotatably coupled to the outer peripheral surfaces of the link hubs 2 and 3 at positions at equal intervals in the circumferential direction.

With reference to FIG. 8, for example, the rotation pair of the base end side link hub 2 and the base end side end link member 5 and the rotation end of the base end side link member 5 and the central link member 7 The structure of the rotating pair will be described.
In the link hub 2, bearing installation holes 31 penetrating between the outer periphery and the through hole 30 </ b> A are formed at three locations equally in the circumferential direction, and the shaft member 33 is formed by two bearings 32 provided in each bearing installation hole 31. Are supported rotatably. The outer end portion of the shaft member 33 protrudes from the link hub 2, and a screw portion 33 a is formed at the tip thereof. The portion of the shaft member 33 protruding from the link hub 2 is inserted into a shaft insertion hole 5a provided at one end of the end link member 5, and the nut 34 screwed into the threaded portion 33a of the shaft member 33 is tightened. The end link member 5 is coupled to the member 33.

  The bearing 32 is a rolling bearing such as a deep groove ball bearing, for example, and an outer ring (not shown) is fitted to the inner periphery of the bearing installation hole 31, and an inner ring (not shown) is the shaft member 33. It is fitted on the outer periphery. The outer ring is retained by a retaining ring 35. Further, a spacer 36 is interposed between the inner ring and the end link member 5, and the tightening force of the nut 34 is transmitted to the inner ring via the end link member 5 and the spacer 36, and a predetermined preload is applied to the bearing 32. Has been granted.

In this proposed example , the bearing 32 provided at the rotating pair of the link hubs 2 and 3 and the end link members 5 and 6 has the outer ring fixed and the inner ring rotated. By providing the bearing 32 in a state of being embedded in the link hubs 2 and 3, the outer shape of the link hubs 2 and 3 can be enlarged without increasing the outer shape of the parallel link mechanism 1 as a whole. Therefore, it is easy to secure a mounting space for mounting the link hubs 2 and 3 to other members.

  The rotation pair of the end link member 5 and the center link member 7 rotatably supports the center link member 7 via a bearing 42 on a shaft member 41 fixed to the end link member 5. The bearing 42 is a rolling bearing such as a deep groove ball bearing, for example, and an inner ring (not shown) of the bearing 42 is fitted to the outer periphery of the shaft member 41, and an outer ring (not shown) of the bearing 42 is attached to the central link member 7. The bearing housing 43 is fixedly fitted to the inner periphery. The shaft member 41 is inserted into a shaft insertion hole 5 b provided in the end link member 5, a spacer 44 interposed between the end link member 5 and the bearing 42, and an inner ring of the bearing 42. The end link member 5 is coupled to the shaft member 41 by tightening the nut 45 screwed to the portion 41a. The tightening force of the nut 45 is transmitted to the inner ring through the spacer 44, and a predetermined preload is applied to the bearing.

Intermediate link member 7, as in the proposed example, constant thickness, is bent at both ends with a constant width of the elongated single metal plate formed in a semicircular shape, in a plate thickness direction at the bent portion 7a of the two locations across It is a curved shape with a predetermined angle γ between them. The bent portion 7a is bent by sheet metal bending. At both ends, a through hole 46 in which the spacer 44 is disposed is provided. The effect of having the central link member 7 in this configuration is the same as that of the above embodiment.

An embodiment of the present invention will be described with reference to FIGS. Each proposed example is a central link member 7 is made of a single plate member, the intermediate link member 7 is Ru Tona two or more sheet material in this embodiment. In the parallel link mechanism shown in FIGS. 9 to 11, the central link member 7 is changed to a structure composed of two plate members as compared with the structure shown in FIGS. Moreover, the parallel link mechanism shown in FIG. 12, FIG. 13 has changed the center link member 7 into the structure which consists of two board | plate materials with respect to what is shown in FIGS.

  The central link member 7 of the parallel link mechanism 1 shown in FIGS. 9 to 11 is composed of a first plate member 51 and a second plate member 52 that face each other and are spaced from each other at a predetermined interval. An end link member 5 having a built-in bearing 53 is disposed between both ends of the second plate members 51 and 52. The first plate member 51 located on the inner side, that is, on the side closer to the posture change center O, has two bent portions 51a in the plate thickness direction, and is located on the outer side, that is, on the side far from the posture change center O. The plate member 52 has one bent portion 52a in the plate thickness direction. That is, the number of second bent portions 52a is smaller than the number of bent portions 51a of the first plate member 51. The bending direction of the bent portions 51a and 52a is a direction in which an intermediate portion of each plate material 51 and 52 protrudes inward. The plate members 51 and 52 are made of, for example, a metal plate, and the bent portions 51a and 52a are bent by sheet metal bending.

  The bearing 53 is a rolling bearing such as a deep groove ball bearing, for example, and an outer ring (not shown) is fitted into the inner periphery of the bearing installation hole 54 of the end link member 5, and an inner ring (not shown) is provided. The rotary shaft 55 fixed to the central link member 7 is fitted on the outer periphery. The rotary shaft 55 is inserted into a through hole 56 provided in the second plate member 52, a cylindrical spacer 57, an inner ring of the bearing 53, a cylindrical spacer 58, and a through hole 59 provided in the first plate member 51. Is done. Then, the nut 60 is screwed onto the threaded portion 55a of the rotating shaft 55, and the plate members 51, 52, the bearing 53, and the spacers 57, 58 are sandwiched between the large diameter portion 55b of the rotating shaft 55 and the nut 60. The end link members 5 and 6 are connected to the rotary shaft 55 in a state where a preload is applied to the bearing 53.

  As described above, when the central link member 7 is configured in such a manner that the two plate members 51 and 52 are arranged in parallel with the plate surfaces facing each other, the strength of the central link member 7 is ensured, and each of the plate members 51 and 52 is secured. The plate thickness can be reduced. Thereby, the central link member 7 can be manufactured at a low cost, and the weight can be reduced. Further, since both ends of the rotating shaft 55 are supported by the two plate members 51 and 52, the rigidity against the moment load of the rotating pair is increased, and the rigidity of the parallel link mechanism 1 as a whole is improved.

  The through hole 56 of the second plate member 52 is a circle having the same diameter as the rotation shaft 55 (FIG. 10) as shown in FIG. 11B, whereas the through hole 59 of the first plate member 51 is. As shown in FIG. 11A, the plate material 51 is a long hole in the longitudinal direction. That is, the through hole 56 of the second plate member 52 is a tight hole in which no gap is generated between the through hole 56 and the rotating shaft 55 inserted through the through hole 56, and the through hole 59 of the first plate member 51 is It is a loose hole in which a clearance is generated between the rotary shaft 55 inserted through the through hole 59. Such through-holes 56 and 59 are devised for improving the assemblability.

  A method for assembling the central link member 7 will be described. First, after the rotating shaft 55 is inserted into the through hole 56 of the second plate member 52 from the outside, the spacer 57, the inner ring of the bearing 53, and the spacer 58 are sequentially fitted into the rotating shaft 55 from the inside. Then, the tip of the rotating shaft 55 is inserted into the through hole 59 of the first plate member 51. Since the two rotary shafts 55 provided at both ends of the central link member 7 have an angle with each other, if the tip of the rotary shaft 55 protrudes larger than the spacer 58, the two rotary shafts 55 are inserted into the through holes 59. Can not do it.

Therefore, with the amount of protrusion of the rotating shaft 55 reduced, the through hole 59 of the first plate member 51 is aligned with the rotating shaft 55, and then the rotating shaft 55 is advanced and inserted into the through hole 59. The through hole 59 of the first plate member 51 is a long hole, and the positioning is flexible. Therefore, it is not necessary to accurately align the rotation shaft 55 and the through hole 59, and the tip of the rotation shaft 55 is positioned at the tip. If only a little protruding from the spacer 58, the rotation shaft 55 can be inserted into the through hole 59 by appropriately shifting or tilting the first plate member 51. Finally, the nut 60 is screwed onto the male screw portion 55a of the rotating shaft 55, and the nut 60 is tightened to complete the assembly of the central link member 7.
With this method, when the through hole 59 is fitted to the rotating shaft 55 whose tip protrudes, visual alignment is possible, and assembly workability is good. Since the rotary shaft 55 is inserted through the through hole 56 of the second member 52 that is a tight hole, the assembly accuracy of the connecting portion between the central link member 7 and the rotary shaft 55 can be ensured.

  The central link member 7 of the parallel link mechanism 1 shown in FIG. 12 and FIG. 13 includes a first plate member 51 and a second plate member 52 that face each other and are spaced apart from each other, and these plate members 51, 52. The two bearing housings 62 are fixed between both ends. Similarly to the above, the first plate member 51 located on the inner side has two bent portions 51a in the plate thickness direction, and the second plate member 52 located on the outer side has one bent portion 52a in the plate thickness direction. . The bearing housing 62 is provided with a bearing 64 that rotatably supports a rotating shaft 63 provided at a rotating pair of the end link member 5 and the central link member 7. In this embodiment, the end link member 5 is also made of a plate material, and the central link member 7 is arranged on the outer diameter side of the end link member 5 that is this plate material.

  The bearing 64 is a rolling bearing such as a deep groove ball bearing, for example. An inner ring (not shown) of the bearing 64 is fitted to the outer periphery of the rotating shaft 63, and an outer ring (not shown) of the bearing 64 is an inner part of the bearing housing 62. It is fitted around the circumference. The rotation shaft 64 is inserted from the inner diameter side into the shaft insertion hole 5 b provided in the end link member 5, the cylindrical spacer 65, the inner ring of the bearing 64, and the cylindrical spacer 66, and the head of the rotation shaft 63 The parts are clamped by 63a and a nut 67 screwed to the threaded portion 63b, so that the bearing 64 is connected to the end link member 5 with a preload applied thereto.

  14 and 15 show a link actuating device using the parallel link mechanism 1 shown in FIGS. 9 to 11. In FIG. 14, the link actuating device 70 includes a parallel link mechanism 1, a base 71 that supports the parallel link mechanism 1, and a plurality of posture changing actuators 72 that actuate the parallel link mechanism 1. By operating the posture changing actuator 72, the posture of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side is changed. A spacer 73 is interposed between the base 71 and the link hub 2 on the base end side of the parallel link mechanism 1. An end effector 74 is installed on the link hub 3 on the distal end side.

  As shown in FIG. 15, the posture change actuator 72 that rotates the end link member 5 on the proximal end side of all three sets of link mechanisms 4 of the parallel link mechanism 1, and the posture change actuator 72 A speed reduction mechanism 81 that decelerates and transmits the operation amount to the end link member 5 on the base end side is provided. The posture changing actuator 72 is a rotary actuator, more specifically, a servomotor with a speed reducer 72 a, and is fixed to the base 71 by a motor fixing member 82. The speed reducing mechanism 81 includes a speed reducer 72 a of the posture changing actuator 72 and a gear type speed reducing portion 83.

  The gear-type speed reducing portion 83 is fixed to the small gear 86 connected to the output shaft 72b of the posture changing actuator 72 via a coupling 85 so as to be able to transmit rotation, and to the end link member 5 on the base end side and fixed to the small gear 86. A large gear 87 that meshes with the gear 86 is formed. For example, the small gear 86 and the large gear 87 are spur gears, and the large gear 87 is a sector gear in which teeth are formed only on the circumferential surface of the sector. The large gear 87 has a larger pitch circle radius than the small gear 86, and the rotation of the output shaft 72 b of the attitude changing actuator 72 is transferred to the end link member 5 on the base end side and the link hub 2 on the base end side and the base end side. It is decelerated and transmitted to the rotation around the rotation axis of the rotation pair with the end link member 5.

  The small gear 86 has shaft portions protruding on both sides of the tooth portion, and each of the shaft portions is rotatably supported by two bearings 88. The two bearings 88 are provided on a rotation support member 89 installed on the base 71. The bearing 88 is a ball bearing such as a deep groove ball bearing or an angular ball bearing. In addition to arranging the ball bearings in a double row as shown in the figure, a roller bearing or a sliding bearing may be used.

  In the illustrated example, a spur gear is used for the gear-type reduction unit 83, but other mechanisms (for example, a bevel gear or a worm mechanism) may be used. In the illustrated example, the large gear 87 is a separate member from the base end side end link member 5 and is detachably attached to the base end side end link member 5 by bolts or the like. The gear 87 may be integrated with the end link member 5 on the base end side.

  The link actuating device 70 can be controlled so as to close the backlash of the parallel link mechanism 1 and the speed reduction mechanism 81 by providing the posture changing actuator 72 and the speed reduction mechanism 81 in all of the three sets of link mechanisms 4. Thus, the positioning accuracy of the link hub 3 on the distal end side is improved, and the rigidity of the link operating device 70 itself can be increased.

  The gear-type reduction unit 83 of the reduction mechanism 81 is a combination of a small gear 86 and a large gear 87, and can obtain a high reduction ratio of 10 or more, for example. If the reduction ratio is high, the positioning resolution of the encoder or the like is increased, and the positioning resolution of the link hub 3 on the distal end side is improved. Further, a low output posture changing actuator 72 can be used. In this embodiment, the posture changing actuator 72 with the speed reducer 72a is used. However, if the reduction ratio of the gear-type speed reducing portion 83 is high, the posture changing actuator 72 without the speed reducer can be used. The posture changing actuator 72 can be reduced in size.

  FIG. 16 shows a link actuating device using the parallel link mechanism 1 of FIGS. The link actuating device 90 includes a parallel link mechanism 1, a base 92 that supports the parallel link mechanism 1, a plurality of posture changing actuators 93 that actuate the parallel link mechanism 1, and operations of these posture changing actuators 93. And a controller 94 that operates the parallel link mechanism 1. A control device (not shown) for controlling the posture changing actuator 93 may be provided in the controller 94 or may be provided separately from the controller 94.

The base 92 is a vertically long member, and the link hub 2 on the base end side of the parallel link mechanism 1 is fixed to the upper surface thereof. A collar-shaped actuator mounting base 95 is provided on the outer periphery of the upper portion of the base 92, and the posture changing actuator 93 is attached to the actuator mounting base 95 in a suspended state. The number of posture changing actuators 93 is three, which is the same as the number of link mechanisms 4. The posture changing actuator 93 is a rotary actuator, and a bevel gear 96 attached to the output shaft of the posture change actuator 93 and a fan-shaped bevel gear 97 attached to the shaft member 33 of the link hub 2 on the base end side mesh with each other.
In this example, the same number of posture changing actuators 93 as the link mechanisms 4 are provided, but if the posture changing actuators 93 are provided in at least two of the three sets of link mechanisms 4, the base end The posture of the link hub 3 on the distal end side with respect to the link hub 2 on the side can be determined.

  The link operating device 90 operates the parallel link mechanism 1 by operating the controller 94 to rotationally drive each posture changing actuator 93. Specifically, when the posture changing actuator 93 is rotationally driven, the rotation is transmitted to the shaft member 33 via a pair of bevel gears 96 and 97, and the proximal end side link member with respect to the proximal end side link hub 2. The angle of 5 changes. Accordingly, the position and posture of the distal end side link hub 3 with respect to the proximal end side link hub 2 are determined. Here, the angle of the end link member 5 on the base end side is changed using the bevel gears 96 and 97, but other mechanisms (for example, a spur gear and a worm mechanism) may be used.

DESCRIPTION OF SYMBOLS 1 ... Parallel link mechanism 2 ... Base end side link hub 3 ... Front end side link hub 4 ... Link mechanism 5 ... Base end side end link member 6 ... Front end side end link member 7 ... Central link member 7a ... Bent part 51 ... first plate material 51a ... bent part 52 ... second plate material 52a ... bent part 53 ... bearing 55 ... rotating shaft 56 ... through hole (tight hole)
59 ... Through hole (loose hole)
62 ... Bearing housing 63 ... Rotating shaft 64 ... Bearing 70 ... Link actuator 72 ... Posture change actuator 90 ... Link actuator 93 ... Posture change actuator

Claims (5)

The link hub on the distal end side is connected to the link hub on the proximal end side through three or more sets of link mechanisms in such a manner that the posture can be changed, and each of the link mechanisms includes a link hub on the proximal end side and a link hub on the distal end side. End link members on the base end side and the tip end side, one end of which is rotatably connected to the link hub, and a center on which both ends are rotatably connected to the other ends of the end link members on the base end side and the tip end side, respectively. A link member,
The central link member includes a first plate member having two or more bent portions in the plate thickness direction, and a second plate member having a smaller number of bent portions in the plate thickness direction than the first plate member. Parallel link mechanism. 2. The parallel link mechanism according to claim 1, wherein the first and second plate members constituting the central link member are metal plates, and the bent portion is formed by sheet metal bending. 3. The parallel link mechanism according to claim 1 , wherein the rotation link portion of the end link member and the central link member includes a bearing between the first plate member and the second plate member. An end link member is arranged, a rotary shaft is inserted into a through hole provided in each of the first plate member and the second plate member, and an inner ring of the bearing, and the first plate member, the second plate member, and the bearing A parallel link mechanism in which the inner ring and the rotating shaft are fixed to each other. 4. The parallel link mechanism according to claim 3 , wherein the through hole provided in one of the first plate member and the second plate member is between the rotation shaft inserted through the through hole. A parallel link mechanism which is a tight hole in which no gap is generated, and the through hole provided in the other plate member is a loose hole in which a gap is formed between the rotation shaft inserted into the through hole. In the parallel link mechanism according to any one of claims 1 to 4, the two or more sets of linkage among the three or more sets of link mechanisms, the distal side relative to the proximal end side link hub A link actuating device comprising a posture changing actuator for arbitrarily changing the posture of a link hub.

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