JPH0325314B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a joint suitable for use in the joints of modular multi-joint robots, which can be expected to perform particularly smooth joint bending movements, and which has high rigidity against expansion and contraction in the axial direction. The purpose of the present invention is to provide a joint that is inexpensive, lightweight, and compact.

Conventionally, the joints of multi-joint robots are composed of a combination of gears or hydraulic and pneumatic cylinders, and the structure is complex, making it difficult to obtain a small and compact one, and the operation lacks smoothness. The configuration was not such that they could be removed and replaced as needed, but had to be designed and manufactured each time depending on the location or purpose of use.

On the other hand, the joint in the patent application filed by the present applicant earlier consists of a pair of housings that are connected to each other so as to be able to rotate relative to each other through spherical contact, and a central rotating shaft and It had a structure in which at least two telescoping shafts were arranged equidistantly around the shaft and facing each other, and the opposing shaft ends of the central rotating shaft and the telescoping shaft were connected to each other by constant velocity joints. This product has a simpler structure than the conventional one, and is easy to unitize as a joint part for a modular multi-joint robot.
There was a problem with the structure of using a constant velocity joint.

That is, the constant velocity joint has a complicated structure as a joint, is difficult to reduce in size and weight, and is not inexpensive. Furthermore, it is difficult to specify the bending center of each joint, and it is difficult to assemble the joints so that the bending centers lie within one plane, so there is a risk that the joint bending operation may become unsmooth.

Therefore, the present invention uses an inconstant velocity joint in place of the above-mentioned constant velocity joint, so that both telescopic shafts can be bent freely, and one joint yoke is rotatably connected to one of the telescopic shafts, and furthermore, both of the telescopic shafts and the central Rotating shafts are connected to each other using bellows so that they can rotate at a constant speed. In this case, the bending center of the inconstant velocity joint is generally easy to identify, so it is easy to adjust the bending center within one plane during assembly, and it has high rigidity against pushing and pulling in the axial direction, and is inexpensive, small, and lightweight. Because it is possible to
In addition to eliminating all the drawbacks of the prior application, it is possible to provide a joint that allows smooth joint bending motion and has high axial rigidity.

The present invention will be explained below with reference to the illustrated embodiments. Fig. 1 is a longitudinal sectional view of an embodiment of the joint for a joint of the present invention, and Fig. 2 is a detailed view of section A in Fig. 1. A member 1 and a distal end side member 2 are arranged to face each other, and each has a central rotating shaft 1.
1, 21 and telescopic shafts 12, 13, 22, 23 are provided. The central rotating shafts 11 and 21 are bearings 1
4 and 24, and are rotatably supported by both housing members 1 and 2, and are connected to each other by bellows 3 so as to be rotatable at a constant speed. The above telescopic shafts 12, 13, 2
2 and 23 are equally spaced around the central rotating shafts 11 and 21 and exist on the same circumference, and 12, 22, 1
3 and 23 are disposed opposite to each other, positioned with respect to each other by an inconstant velocity joint 4 and a bellows 5, and are connected so as to be bendable and rotatable at a constant velocity, as will be described later with reference to FIG.

All of these telescoping shafts have equally pitched male threaded portions, which are screwed into female threaded portions 15, 16, 25, and 26 that are threaded or embedded in both the members 1 and 2, respectively. However, the internal threads 15 and 25, 16 and 26, and 15 and 16 are threads in opposite directions, for example, 15 and 26 are right-handed threads, and 16 and 25 are threads in opposite directions.
is a left-handed screw, and when both the telescopic shafts 12 and 13 are rotated clockwise, the opposing telescopic shafts 12 and 22 both move toward the connecting part at the same speed and by the same amount (referred to as extension),
The other opposing telescopic shafts 13 and 23 both move at the same speed and by the same amount in the opposite direction (referred to as contraction), and as a result, the distal side enclosure member 2 is moved to the right side of the figure with respect to the proximal side enclosure member 1. Causes joint bending movement in the direction.

In FIG. 1, reference numeral 111 indicates the central rotating shaft 1.
1 and a pinion 71 fixed to a rotational drive source 71 such as a pulse motor or an air motor.
It meshes with 1. Similarly, the code 121 is the telescopic axis 1
The wide gear 131 on the telescopic shaft 13 meshes with the pinion 721 fixed on the rotary drive source 72 via the intermediate gear 6. The intermediate gear 6 is rotatably supported on the central rotating shaft 11 by a bearing 61. In addition, the lower end portions of the telescopic shafts 12 and 13 are linear motion bearings 8.
1 on the lid 1' of the base side enclosure member 1. The upper end portions of the telescopic shafts 22 and 23 are also supported by the lid 2' of the distal end side casing member 2 by linear motion bearings 82.
Furthermore, if the threaded portion is formed as a ball screw, the movement of each telescopic shaft will be more accurate and precise.

Next, the details of the joint portions of the telescopic shafts will be explained with reference to FIG. 2.
Bellows mounting flanges 51 and 52 are fixed to each opposing shaft end of 2, and both are connected by a bellows 5. A driving side yoke 41 of the inconstant velocity joint 4 is further fixed to the shaft ends of the telescopic shafts 13 and 12, and the driven side yoke 42 is rotatably supported on the flange 52 via a shaft 44 and a bearing 45. be. Reference numeral 43 is a cross pin. The above is an example using a so-called cross-axis universal joint,
A similar configuration can be achieved using a well-known top-shaped universal joint.

In the joint of the embodiment of the present invention having the above configuration, the telescopic shaft 12 is
When rotated, the telescopic shafts 12 and 22 move toward or away from the joint as described above due to the screw action. At the same time, gear train 12
1, 6, and 131 cause the telescopic shafts 13 to rotate synchronously, and the telescopic shafts 13, 23 move by the same amount in the opposite direction to the telescopic shafts 12, 22 due to the screw action. As a result, the distal side casing member 2 is inclined in the left-right direction in the figure with respect to the base side casing member 1, resulting in so-called joint bending motion. At this time, the bisector of the angle formed by the telescopic axes 12 and 22 and the bisecting surface of the angle formed by the telescopic axes 13 and 23 always coincide during the joint bending motion, so the above bending motion is extremely It's smooth.

In the case of this embodiment, there are two pairs of telescopic axes on the left and right, so joint bending is only in the left and right directions in the figure, but if there are three or more pairs of telescopic axes, joint bending in all directions is possible. However, at this time, the bending center of each joint must always lie within one plane as described above. When using the constant velocity joint of the earlier application, it is difficult to assemble in one plane for the reasons mentioned above, and it is difficult to obtain a satisfactory result, but with the non-constant velocity joint of the present invention, , the bending center is the center point of the cross pin 43 or, in the case of a top-shaped universal joint, the center point of the drive pin attached to the top, so that the position does not change during the bending movement, and the position can be easily adjusted during assembly. Because of this, smooth joint bending movements can be achieved. In addition, the joint of the present invention has high rigidity against pushing and pulling in the axial direction, is inexpensive, easy to reduce in size and weight, and can be easily made into a unit, so it can be used for precise and precise modular articulated robot joints. Suitable as a joint.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a detailed view of section A in FIG. Explanation of symbols: 1...Base side casing member, 2...Tip side casing member, 3, 5...Bellows, 4...Inconstant velocity joint, 11...Central rotating shaft, 12, 13, 2
2, 23... telescopic shaft, 71, 72... rotary drive source.

Claims (1)

[Scope of Claims] 1. A base side case member and a distal side case member arranged to face each other, each of both case members has a central rotating shaft and a central rotating shaft equally spaced around the central rotating shaft. At least two telescoping shafts are arranged to face each other, and the driving side of a non-uniform velocity joint is fixed to the opposing shaft ends of the telescoping shafts provided on the base side enclosure member, and the driving side of the non-uniform velocity joint is fixed. The driven side of the housing member is rotatably supported by a bearing on the opposing shaft end of each telescoping shaft disposed on the distal end side housing member, and furthermore, the central rotating shaft and the opposing shaft end of the telescoping shaft of both housing members are each supported by a bellows. A joint characterized in that the inconstant velocity joints are connected to each other so as to be rotatable at a constant velocity, and the respective extension/contraction axes are extended/contracted in relation to each other so that the respective bending centers of the respective inconstant velocity joints always lie within one plane. joint. 2. The telescoping shafts disposed on the base side casing member and the tip side casing member are ball screw type telescoping shafts, and each has a ball nut threaded or fixed to both of the casing members, and a series of balls connected to each of the ball nuts. A joint according to claim 1, comprising a male threaded rod screwed together. 3. The joint according to claim 1 or 2, wherein the inconstant velocity joint is a so-called cross-shaft universal joint consisting of a cross pin, a yoke, etc. 4. The joint for a joint according to claim 1 or 2, wherein the inconstant velocity joint is a so-called top-shaped universal joint consisting of a top, a drive pin, a yoke, etc.