JP5187232B2 - Universal joint - Google Patents

Description

  The present invention relates to a universal joint in which a bearing unit is combined, and more particularly to a universal joint that can be used for a base portion of a finger of a robot hand.

In Patent Document 1, a joint is provided in which the base portion of the finger of the humanoid robot hand intersects at right angles so as to bend up, down, left and right. More specifically, as shown in FIG. 4, the axis J _2.0 of the joint of the metacarpal bone and the axis J _2.1 of the joint between the metacarpal bone and the proximal phalanx are arranged orthogonally. A wiring cable for a joint driving motor, a sensor or the like built in the finger mechanism is provided by providing a space at the intersection.

Japanese Patent No. 3848123

  However, in Patent Document 1, although not clearly described, it is not configured to use a rolling bearing as can be seen from the drawings, and a sliding bearing in which a pin provided on one sheet metal is provided on the other sheet metal. There is a problem that the minute movement of the finger cannot be performed smoothly because the bearing portion is loose due to the hollow formed at the intersection and through the wiring cable.

  Therefore, an object of the present invention is to provide a universal joint that can smoothly perform fine operations.

In order to achieve the above object, a universal joint according to the present invention is characterized by the following (1) to (7).
(1) a first bearing unit that fits two rolling bearings between a first shaft member and a first housing and rotatably supports the first housing with respect to the first shaft member;
A second bearing unit that fits two rolling bearings between a second shaft member and a second housing, and rotatably supports the second housing with respect to the second shaft member;
The two rolling bearings incorporated in the first bearing unit and the second bearing unit, respectively, are preloaded before assembling the first bearing unit and the second bearing unit,
The first housing is provided with a female thread portion at the bulging portion where the outer rings of the two rolling bearings incorporated therein contact , and the second shaft member is provided with a male screw portion, and the first bearing unit and the first bearing 2. The universal joint, wherein the male screw portion and the female screw portion are screwed so that the rotation shafts of the two bearing units are orthogonal to each other.
(2) The distance between the bearings of the first bearing unit is longer than the distance between the bearings of the second bearing unit, and the second shaft member is fixed between the rolling bearings of the first bearing unit. The universal joint according to (1).
(3) A flat surface is provided on the outer peripheral surface of the first housing,
A flange portion is provided on one axial direction of the second shaft member,
The universal joint according to (1) or (2), wherein the flat surface and the flange portion abut.
(4) The universal joint according to (3), wherein a male screw portion is provided on the outer peripheral surface on the other axial side of the second housing.
(5) A notch portion in which the first housing and the first shaft member are notched is provided between the rolling bearings of the first bearing unit in a direction orthogonal to the rotation shaft of the first bearing unit. The universal joint according to any one of (1) to (4), wherein at least one of an electrical cable and a drive wire is loaded in the notch.
(6) The universal joint according to any one of (1) to (5), wherein the universal joint is used at a base portion of a finger of a robot hand.

According to the universal joint of the present invention, the first and second bearing units, each having two rolling bearings, are fixed so that the respective rotation axes are orthogonal to each other. The operation can be performed smoothly.
Further, the first and second bearing units are provided with a female screw portion in the first housing of the first bearing unit, a male screw portion in the second shaft member of the second bearing unit, and screwed together to fix them. Even if it uses a rolling bearing, it can be attached easily.

It is a perspective view showing one embodiment of a universal joint according to the present invention. It is sectional drawing of the universal joint of FIG. It is a fragmentary sectional view of the base of the finger of a robot hand provided with the universal joint concerning the present invention. 10 is a perspective view of a finger base portion of a robot hand described in Patent Document 1. FIG.

Hereinafter, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view schematically showing a universal joint according to the present invention, and FIG. 2 is a sectional view of the universal joint of FIG.

  As shown in FIGS. 1 and 2, the universal joint 1 is configured by combining two bearing units 2 and 3, and the rotation axes P <b> 1 and P <b> 2 are orthogonal to each other.

The first bearing unit 2 is a component in which two sets of ball bearings 22, 23, a single outer ring housing 24 (first housing), and a single shaft member 25 (first shaft member) are integrated. .
Of the two sets of ball bearings, one of the ball bearings 22 includes an outer ring 22a and an inner ring 22b, a number of balls 22c disposed between the raceway grooves of the outer ring 22a and the raceway grooves of the inner ring 22b, and an outer ring 22a. And an annular seal body 22d that closes both ends in the axial direction between the inner ring 22b and a retainer (not shown) that holds the balls 22c at equal intervals in the circumferential direction. Further, the other ball bearing 23 also has a large number of balls 23c that are rotatably arranged between the outer ring 23a and the inner ring 23b having the same shape as the one ball bearing 22, and the raceway grooves of the outer ring 23a and the raceway grooves of the inner ring 23b. And an annular seal body 23d that closes both axial ends between the outer ring 23a and the inner ring 23b, and a retainer (not shown) that holds the balls 23c at equal intervals in the circumferential direction.

The material of the outer rings 22a and 23a, the inner rings 22b and 23b, and the balls 22c and 23c is a bearing steel (for example, SUJ2, SUJ3, etc.) under standard use conditions, but is a stainless steel that is a corrosion-resistant material depending on the use environment. Materials (for example, martensitic stainless steel materials such as SUS440C, austenitic stainless steel materials such as SUS304, precipitation hardening stainless steel materials such as SUS630), titanium alloys and ceramic materials (for example, Si ₃ N ₄ , SiC, Al ₂₎ O ₃ , ZrO _2, etc.) may be employed.

  The outer ring housing 24 is a hollow cylindrical member into which the outer rings 22a and 23a of the two sets of ball bearings 22 and 23 are fitted. A bulging portion 24a bulging toward the inner diameter side is formed at a substantially central portion in the axial direction of the inner peripheral surface, and ball bearings 22 and 23 are provided so as to sandwich the bulging portion 24a. A flat surface 24b extending in the axial direction is formed on a part of the outer peripheral surface. A screw hole in which a female screw portion 24c that penetrates the bulging portion 24a in the radial direction is formed at a substantially central portion of the flat surface 24b in the axial direction, and the diameter of the screw hole is opposite to the screw hole. A substantially semicircular cutout 24d is provided in a cross section in the direction perpendicular to the axis that is longer and smaller than the width of the bulging portion 24a.

  The shaft member 25 is a hollow cylindrical member that externally fits the inner rings 22b, 23b of the ball bearings 22, 23, and female threads 25a are formed on the inner peripheral surface from both ends in the axial direction. Further, the shaft member 25 is formed with a notch 25b at a position corresponding to the notch 24d of the outer ring housing 24 surrounding the shaft member 25. The notches 25b and 24d have an electrical cable or drive (not shown). The wire is loaded. In addition, the end of the shaft member 25 and the outer ring housing 24 is provided with marks such as a groove and a notch for aligning the notch 25b of the shaft member 25 and the notch 24d of the outer ring housing 24. Here, in the ball bearings 22 and 23, the outer rings 22a and 23a are positioned on the bulging portion 24a of the outer ring housing 24, and preload is applied by displacing the inner rings 22b and 23b toward the inner side in the axial direction. Note that the preload setting method may be a preload setting in which the resonance frequency is controlled by adhesion fixing or press-fit fixing while applying a preload, and the contents of Japanese Patent Nos. 3419015 and 3254825 are incorporated herein by reference.

Similar to the first bearing unit 2, the second bearing unit 3 is a component in which two sets of ball bearings 32, 33, a single outer ring housing 34, and a single shaft member 35 are integrated.
Of the two sets of ball bearings, one of the ball bearings 32 includes an outer ring 32a and an inner ring 32b, a plurality of balls 32c disposed between the raceway grooves of the outer ring 32a and the raceway grooves of the inner ring 32b, and an outer ring 32a. And an annular seal body 32d that closes both axial ends between the inner ring 32b and a retainer (not shown) that holds the balls 32c at equal intervals in the circumferential direction. Further, the other ball bearing 33 also has a large number of balls 33c that are rotatably arranged between the outer ring 33a and the inner ring 33b having the same shape as the one ball bearing 32, and the raceway grooves of the outer ring 33a and the raceway grooves of the inner ring 33b. And an annular seal body 33d that closes both axial ends between the outer ring 33a and the inner ring 33b, and a retainer (not shown) that holds the balls 33c at equal intervals in the circumferential direction. A spacer 36 is provided between the outer rings 32a and 33a of the ball bearings 32 and 33, and the distance between the ball bearings 32 and 33 is the distance between the ball bearings 22 and 23 of the first unit 2. It is set shorter.

  As the materials of the outer rings 32a and 33a, the inner rings 32b and 33b, and the balls 32c and 33c, the same materials as the outer rings 22a and 23a, the inner rings 22b and 23b, and the balls 22c and 23c of the first bearing unit 2 are used.

  The outer ring housing 34 (second housing) is a hollow cylindrical member in which the outer rings 32a and 33a of the two sets of ball bearings 32 and 33 are fitted. A flange portion 34a is provided on one side in the axial direction of the outer peripheral surface, and a male screw portion 34b is provided on the other side.

  The shaft member 35 (second shaft member) is a solid cylindrical member that externally fits the inner rings 32b and 33b of the ball bearings 32 and 33, and a flange portion 35a is provided on the outer peripheral surface on one axial side. The male screw portion 35b having a smaller diameter extends from the flange portion 35a than the flange portion 35a. Further, a slit 35c is formed at the tip on the other side in the axial direction. A hexagonal hole may be formed instead of the slot 35c. Here, the inner ring 32b of the ball bearing 32 is positioned on the flange portion 35a of the shaft member 35, and preload is applied by displacing the outer ring 33a of the ball bearing 33 toward one side in the axial direction, that is, toward the flange 35a. ing.

  The first and second bearing units 2, 3 configured in this way have through holes formed in the outer ring housing 24 of the first bearing unit 2 by applying a tool to the slot 35 c of the second bearing unit 3. The male screw portion 35b of the shaft member 35 of the second bearing unit 3 is fixed to the female screw portion 24c by screwing. At this time, the flange portion 35 a provided on the shaft member 35 of the second bearing unit 3 abuts on the flat surface 24 b formed on the outer ring housing 24 of the first bearing unit 2, so that the outer ring housing 34 of the second bearing unit 3 contacts the outer ring housing 34. The provided flange portion 34a faces a flat surface 24b formed on the outer ring housing 24 of the first bearing unit 2 with a predetermined gap therebetween.

  FIG. 3 shows the universal joint 1 of the present embodiment applied to the base of the finger of the robot hand. The palm portion 6 is connected to the female screw portion 25a of the shaft member 25 of the first bearing unit 2, and the second The finger portion 7 is fixed to the outer ring housing 34 of the bearing unit 3 by a nut 8 screwed into the female screw portion 34. Then, the outer ring housing 24 of the first bearing unit 2 and the outer ring housing 34 of the second bearing unit 3 are provided with drive wires and gears, and power is supplied by a drive force transmission device (not shown) such as a motor, so that the finger portion 7 It can rotate around the rotation axis P <b> 1 of the one bearing unit 2, and can also rotate around the rotation axis P <b> 2 of the second bearing unit 3.

As described above, according to the universal joint 1 of the present embodiment, the first and second bearing units 2 and 3 in which the two ball bearings 22, 23, 32, and 33 are respectively arranged are respectively rotating shafts. Since P1 and P2 are fixed so as to be orthogonal to each other, fine operations can be smoothly performed even when the load is large.
The first and second bearing units 2 and 3 are provided with a female thread portion 24c in the outer ring housing 24 of the first bearing unit 2 and a male thread portion 35b in the shaft member 35 of the second bearing unit 3, and are screwed together. Therefore, even if a rolling bearing is used, it can be easily attached.

  Further, according to the universal joint 1 of the present embodiment, the distance between the bearings of the first bearing unit 2 is longer than the distance between the bearings of the second bearing unit 3, and the second distance between the ball bearings 22 and 23 of the first bearing unit 2. Since the shaft member 35 of the bearing unit 3 is fixed, the stability can be improved.

Further, according to the universal joint 1 of the present embodiment, a flat surface 24b is provided on the outer peripheral surface of the outer ring housing 24 of the first bearing unit 2, and a flange is provided on one axial direction of the shaft member 35 of the second bearing unit 3. Since the portion 35a is provided and the flat surface 24b and the flange portion 35a come into contact with each other, the stability can be improved by the surface contact between the flat surface 24b and the flange portion 35a.
Further, the flange portion 35 a can be used as a pressing portion for the inner ring 32 b of the ball bearing 32.

  Moreover, according to the universal joint 1 of this embodiment, since the external thread surface 34b is provided in the other outer peripheral surface of the outer ring housing 34 in the axial direction, it is easily attached when the universal joint 1 is incorporated into another device. be able to.

  Further, according to the universal joint 1 of the present embodiment, the notches 24d and 25b are provided between the ball bearings 22 and 23 of the first bearing unit 2 in a direction orthogonal to the rotation axis P1 of the first bearing unit 2. In addition, since at least one of the electrical cable and the drive wire can be loaded in the notches 24d and 25b, the space can be used effectively.

  Also, by preloading the ball bearings 22, 23, 32, 33 built in the first bearing unit 2 and the second bearing unit 3, the bearing rigidity can be improved, and a universal bearing 1 can be used by using a smaller bearing. The whole can be reduced in size.

  The universal joints used in the joint portions of the above embodiments are not limited to those exemplified in the embodiments of the above embodiments, and can be changed as appropriate without departing from the scope of the present invention. . In FIG. 3, the universal joint 1 is applied to the base of the finger of the robot hand as an application example. However, the invention is not limited to this. For example, the universal joint 1 can also be applied to a freely swinging fulcrum of a laser marking device.

1 Universal Joint 2 First Bearing Unit 22, 23 Ball Bearing (Rolling Bearing)
24 Outer ring housing (first housing)
24b Flange part 24c Female thread part 24d Notch part 25 Shaft member (1st shaft member)
25b Notch 3 Second bearing unit 32, 33 Ball bearing (rolling bearing)
34 Outer ring housing (second housing)
34b Male thread portion 35 Shaft member (second shaft member)
35a Flange part 35b Male thread part P1, P2 Rotating shaft

Claims (6)

A first bearing unit that fits two rolling bearings between a first shaft member and a first housing, and rotatably supports the first housing with respect to the first shaft member;
A second bearing unit that fits two rolling bearings between a second shaft member and a second housing, and rotatably supports the second housing with respect to the second shaft member;
The two rolling bearings incorporated in the first bearing unit and the second bearing unit, respectively, are preloaded before assembling the first bearing unit and the second bearing unit,
The first housing is provided with a female thread portion at the bulging portion where the outer rings of the two rolling bearings incorporated therein contact , and the second shaft member is provided with a male screw portion, and the first bearing unit and the first bearing 2. The universal joint, wherein the male screw portion and the female screw portion are screwed so that the rotation shafts of the two bearing units are orthogonal to each other.   The distance between the bearings of the first bearing unit is longer than the distance between the bearings of the second bearing unit, and the second shaft member is fixed between the rolling bearings of the first bearing unit. The universal joint according to 1. A flat surface is provided on the outer peripheral surface of the first housing,
A flange portion is provided on one axial direction of the second shaft member,
The universal joint according to claim 1, wherein the flat surface is in contact with the flange portion.   4. The universal joint according to claim 3, wherein a male screw portion is provided on the other outer peripheral surface in the axial direction of the second housing. A notch portion in which the first housing and the first shaft member are notched is provided between the rolling bearings of the first bearing unit in a direction perpendicular to the rotation shaft of the first bearing unit. universal joint according to any one of claims 1 to 4 in-out portion, characterized in that at least one of the electrical cable and the driving wire is loaded. Universal joint according to any one of claims 1 to 5, characterized in that used in the base portion of the finger of the robot hand.

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