JP2012172764A - Spherical bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spherical bearing having a rolling bearing structure, capable of securing a relatively large allowable inclination while minimizing friction resistance without backlash.SOLUTION: The spherical bearing includes: a shaft member 1 having a shank portion 3 and a spherical portion 4 formed at a tip of the shank portion; a housing 2 having a chamber space 7 formed to house the spherical portion with the shank portion being exposed to the outside; an adjustment screw 13 screwed to a screw hole 12 formed in the housing to extend from the outside of the housing to the chamber space; an adjustment plate 8 installed inside the chamber space so as to be capable of contacting the tip of the housed spherical portion; and a slide piece 14 installed within the chamber space so as to be capable of contacting the side surface of the housed spherical portion, the slide piece being curved along the spherical portion in the contact part with the spherical portion.

Description

  The present invention relates to a spherical bearing that has a simple and compact structure and can have a large swivel motion range.

  In recent years, with the advancement of robot technology, there has been an increasing demand for, for example, miniaturization of joints or bearings for use in connecting portions of robot arms and a wide operating range of arms.

  As a conventional example of such a joint or bearing, for example, there is one shown in Patent Document 1. In this patent document 1, with respect to the spherical bearing by the so-called sliding bearing method so far, in such a spherical bearing, a gap is required between the tip end portion of the rod and the outer peripheral member, so that play occurs. It has been pointed out that if this gap is reduced, the contact resistance between the tip of the rod and the outer peripheral member increases and the movement becomes dull.

JP 2000-304039 A

  However, a spherical bearing having a rolling bearing structure incorporating a large number of balls as in the invention described in the above-mentioned Patent Document 1 inevitably increases the number of parts, making it difficult to manufacture, and simplifying the structure. Then difficulties arise. Compared with this, the spherical bearing by the sliding bearing system has an advantage that the configuration can be simplified compared with the spherical bearing by the rolling bearing system, and the performance is not easily deteriorated even if used for many years.

  The present invention has been proposed from such a background, and an object of the present invention is to provide a spherical bearing having a plain bearing structure that is simple in structure, has no backlash, and has low frictional resistance.

  In order to achieve the above object, a spherical bearing according to the present invention includes a shaft body portion, a shaft member having a sphere portion formed at the tip of the shaft body portion, and the shaft member exposed to the outside. A housing in which a chamber space for accommodating the sphere portion is formed, a screw screwed into the housing with a screw hole formed from the outside of the housing toward the chamber space, and the chamber space. An adjustment plate installed so as to be able to come into contact with the distal end portion of the accommodated sphere portion, and a contact portion which is placed so as to be able to come into contact with the side surface of the contained sphere portion in the chamber space And a slide piece curved along the sphere. In this configuration, the screw advances along the screw hole, pushes against the adjustment plate, pushes the adjustment plate against the tip of the spherical body portion, and a gap between the shaft member and the inner surface of the housing. Adjust. Thereby, the spherical bearing of a slide bearing structure is provided.

  In the present invention, the spherical portion of the shaft member is accommodated in the chamber space of the housing, while the adjustment plate is brought into contact with the tip of the spherical portion in the chamber space, and the slide piece is brought into contact with the side surface of the spherical portion. Since the sphere part is in contact with and supported, the spherical part makes point contact with the adjustment plate, and also makes sliding movement in line or surface contact with the slide piece, and there is no backlash. A spherical bearing with low frictional resistance can be realized. In addition, since the adjusting plate abuts on the tip of the spherical body portion and pushes the shaft member toward the shaft body portion (in the axial direction, the direction of pushing out from the chamber space), the allowable inclination angle when the shaft member rotates is set. The effect that it can be made variable and the inclination angle can be made relatively large is also obtained.

It is front sectional drawing which shows the structure of the spherical bearing which concerns on one embodiment of this invention. It is the fragmentary sectional view and bottom view which show the structure of the slide piece used for the spherical bearing which concerns on the said embodiment. It is a partially broken perspective view which shows the internal structure of the spherical bearing which concerns on the said embodiment. It is a perspective view which shows the example which used the spherical bearing which concerns on the said embodiment for a parallel link mechanism.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view showing the structure of a spherical bearing according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a shaft member that serves as an operating portion of the spherical bearing, and 2 denotes a housing that accommodates and holds the shaft member 1. The shaft member 1 includes a rod-shaped shaft body portion 3 that transmits an operating force from the outside to the shaft member 1 and a spherical body portion 4 that is integrally formed at the tip of the shaft body portion 3. A threaded portion 5 for coupling the shaft member 1 to another mechanical element is provided at the base end portion (the end portion opposite to the spherical body portion 4) of the shaft body portion 3. The housing 2 has a first housing divided body 2a having a block structure that has a first concave portion 7a and constitutes a base portion of the housing 2, and a ceiling portion that has a second concave portion 7b and is combined with the first housing divided body 2a. The two housing divided bodies 2a and 2b are coupled by a coupling screw 6 to form the housing 2. Inside the housing 2, a first recess 7 a and a second recess 7 b are formed to form a chamber space 7 for accommodating the shaft member 1 and the spherical body portion 4 with the shaft body portion 3 exposed to the outside. Has been. The chamber space 7 is formed in a substantially cylindrical space shape, and an adjustment plate 8 is provided near the bottom surface of the chamber space 7 so as to contact the tip of the accommodated sphere portion 4 and support the sphere portion 4. The adjusting plate 8 is made of a material having a small frictional resistance such as a synthetic resin. In the middle portion in the vertical direction of the chamber space 7, a shelf portion 9 is formed in which the diameter of the cylindrical space of the chamber space 7 is expanded stepwise from the lower part to the upper part. Further, an opening 10 is formed in the ceiling portion of the housing 2 above the shelf 9 by a predetermined dimension, and the chamber space 7 is communicated with the outside. The opening 10 is formed in a tapered shape of an inverted truncated cone that gradually decreases in diameter from the upper surface side (front surface side) to the lower surface side (back surface side) in the thickness direction (vertical direction) of the ceiling, and corresponds to the opening 10. The lower surface of the ceiling of the housing 2 forms an eaves portion 11 that extends radially inward with respect to the chamber space 7. On the other hand, at the base of the housing 2, a screw hole 12 is formed in the bottom plate of the second housing divided body 2 b so as to communicate from the outside of the housing 2 to the chamber space 7, and an adjustment screw 13 is screwed into the screw hole 12. Are combined. The adjustment screw 13 is installed so as to advance into the chamber space 7 by being screwed into the screw hole 12 and to hit the adjustment plate 8 to support the spherical body portion 4. Further, by increasing or decreasing the screwing amount of the adjusting screw 13, it is possible to tighten, loosen or adjust the degree of support of the spherical body portion 4 in the chamber space 7.

  Further, in the chamber space 7 of the housing 2, a slide piece 14 is disposed at a stepped widened portion sandwiched between the shelf portion 9 and the flange portion 11 described above. Similar to the adjustment plate 8, the slide piece 14 is made of a material having a small frictional resistance such as a synthetic resin. The housing divided bodies 2a and 2b are made of a metal material. 2 is a diagram showing the configuration of the slide piece 14, FIG. 2 (a) is a partial sectional front view showing the substantially right half of the slide piece 14 in cross section, and FIG. 2 (b) is a bottom view of the slide piece 14. . As shown in FIGS. 2A and 2B, the slide piece 14 is entirely formed into a ring structure, and its inner peripheral surface extends non-parallel to the center axis of the ring. Molded. That is, as shown in FIG. 2 (a), when the slide piece 14 has its vertical width divided from an intermediate part into an upper part a and a lower part b, the slide piece 14 is a slide piece. A curved portion 15 is provided so that the inner peripheral surface of 14 is slightly reduced in diameter from the inner position to the opening position at the upper end. The curved portion is formed to extend in the circumferential direction on the inner peripheral surface of the slide piece 14. On the other hand, for the portion b, the inner peripheral surface of the slide piece 14 is a straight portion 16 that extends straight from the inner position to the opening position at the lower end. Regarding the inner peripheral diameter of the slide piece 14, the diameter of the straight portion 16 is substantially the same as the diameter of the spherical portion 4, and the diameter of the curved portion 15 is smaller than the diameter of the spherical portion 4. When the shaft member 1 is mounted in the housing 2, the slide piece 14 having such a structure abuts against the side surface of the sphere portion 4 accommodated in the chamber space 7 to support the sphere portion 4. 1 is prevented from coming out of the opening 10 in the ceiling portion of the housing 2.

  In order to assemble the spherical bearing according to the present embodiment, the following procedure is performed. First, the upper end of the slide piece 14 is placed in contact with the flange 11 in the second recess 7b of the second housing divided body 2b. Next, the shaft member 1 is arranged such that the shaft body portion 3 protrudes from the inside to the outside through the opening 10 of the second housing divided body 2b. Since the slide piece 14 has the structure in which the curved portion 15 is formed as described above, the spherical body portion 4 is supported by the slide piece 14 and does not come out of the opening 10. On the other hand, in the 1st housing division body 2a, an adjustment board is arrange | positioned in the 1st recessed part 7a. After the above arrangement work of each member, the first housing divided body 2a (lower side) and the second housing divided body 2b (upper side) are assembled and coupled by the coupling screw 6 to form the housing 2. Thereafter, the adjusting screw 13 is screw-engaged with the screw hole 12 formed in the first housing divided body 2 a and brought into contact with the adjusting plate 8.

  As described above, the spherical body portion 4 of the shaft member 1 is supported in the distal end portion and the side surface portion by the adjustment plate 8 and the slide piece 14 in the chamber space 7 and is capable of sliding movement with respect to the adjustment plate 8 and the slide piece 14. Thus, the shaft member 1 as a whole is a three-degree-of-freedom rotating body. FIG. 3 is a partially broken perspective view showing the internal structure of the spherical bearing according to the present embodiment. Further, when the adjustment screw 13 is screwed, the adjustment screw 13 moves forward along the screw hole 12 and pushes against the adjustment plate 8 to bring the adjustment plate 8 into contact with the distal end portion of the sphere portion 4 so as to contact the sphere. The portion 4 is pressed against the curved portion 15 of the slide piece 14 and supported with a slightly strong support force. Thereby, in the spherical bearing of the slide bearing structure, when the shaft member 1 rotates, the contact between the spherical body portion 4 and the adjusting plate 8 and the slide piece 14 becomes tighter, and play and the like can be said at all. Does not occur. The shaft member 1 can rotate in a range of an allowable inclination angle (represented by θ in FIG. 1). In the present embodiment, the adjustment plate 8 is brought into contact with the tip of the sphere part 4 and the slide piece 14 is supported so as to surround the side surface of the sphere part 4, so that the sphere part 4 is adjusted. A point contact with the plate 8 and a linear contact or a surface contact with the slide piece 14 cause a relative sliding operation, and it is possible to realize a spherical bearing with no friction and a small frictional resistance. .

  In FIGS. 1 and 3, reference numeral 17 denotes a spacer plate. This is because, when the shaft member has some kinds of variations in dimensions, the dimensions of the sphere portion 4 are different, and the adjustment screw 13 has a different amount of screwing in order to compensate for the difference in screwing amount. Is to be placed. Further, reference numeral 18 in FIG. 1 represents a mounting screw for mounting the spherical bearing of the present invention to another mechanical device.

  The spherical bearing having the above-described configuration according to the present invention can be used for various mechanisms as a joint device. FIG. 4 is a perspective view showing an example in which a spherical bearing is used in a parallel link mechanism as an application example thereof. The parallel link mechanism includes a table 20 serving as a base, a plurality of motors 21 that are drive members attached to the table 20, a plurality of drive-side arms 22 that are connected to the motor 20 and driven, and a drive-side arm 22. And a plurality of driven arms 23 connected to each other and an operating table 24 attached to the tip of the driven arm 23. A workpiece is attached to the operation table 24, and the operation table performs various operations according to various operations of the motors 21 to process the workpiece. Alternatively, it is possible to attach a machining unit to the operation table 24 and machine a workpiece at the destination of the machining unit. In such a parallel link mechanism, for example, by providing the spherical bearing 25 of the present embodiment at the connecting portion between the driving side arm 22 and the driven side arm 23, power transmission between the driving side arm 22 and the driven side arm 23 is performed. The follower arm 23 can correctly follow the operation table 24 and transmit a complicated movement from the drive side arm 22. In FIG. 4, a trunnion-structured joint is used at the connecting portion between the operating table 24 and the driven arm 23, but the spherical bearing 25 of the present embodiment can also be provided at this portion. In the above description, the housing 2 is made of metal and the adjustment plate 8 and the slide piece 14 are made of synthetic resin. However, the housing 2 and the slide piece 14 may be integrally formed of synthetic resin.

  In the present invention, the spherical portion of the shaft member is accommodated in the chamber space of the housing, while the adjustment plate is brought into contact with the tip of the spherical portion in the chamber space, and the slide piece is brought into contact with the side surface of the spherical portion. Since it is supported by contact, it is possible to realize a spherical bearing with a simple structure, no play and low frictional resistance. Further, by pushing the adjustment plate toward the spherical body, industrial usefulness can be obtained such that the allowable inclination angle when the shaft member rotates can be varied.

DESCRIPTION OF SYMBOLS 1 Shaft member 2 Housing 3 Shaft part 4 Sphere part 5 Screw part 6 Coupling screw 7 Chamber space 8 Adjustment plate 9 Shelf part 10 Opening 11 Gutter part 12 Screw hole 13 Adjustment screw 14 Slide piece 15 Curved part 16 Linear part 17 Spacer plate 18 Mounting screw 24 Spherical bearing

Claims (4)

A shaft member, and a shaft member having a sphere formed at the tip of the shaft body;
A housing in which a chamber space for accommodating the spherical body portion is formed in a state where the shaft body portion is exposed to the outside.
A screw screwed into a screw hole formed in the housing from the outside of the housing toward the chamber space;
In the chamber space, an adjustment plate installed so as to be able to contact the tip of the accommodated sphere,
In the chamber space, it is installed so as to be able to come into contact with the side surface of the accommodated sphere part, and consists of a slide piece curved along the sphere part at the contact part to the sphere part,
The screw advances along the screw hole, hits against the adjustment plate and pushes, the adjustment plate is brought into contact with the tip of the sphere portion, and the sphere portion is pressed against the slide piece, and the shaft member is moved inside the housing. Spherical bearing characterized by being supported by.   2. The spherical bearing according to claim 1, wherein the adjusting plate is made of a material having a small frictional resistance such as a synthetic resin.   3. The slide piece as a whole is formed into a ring structure, and a curved portion is provided on an inner peripheral surface of the slide piece so as to be slightly reduced in diameter from the bottom to the top. Spherical bearings.   2. The spherical bearing according to claim 1, wherein the slide piece is made of a material having a small frictional resistance such as a synthetic resin.

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