JPH05187505A - Linear-motion mechanism - Google Patents

Abstract

PURPOSE:To provide a linear-motion mechanism with small backlash which can bear a heavy load. CONSTITUTION:A passive rack 11 has wave-shaped teeth, three discs 12 are rotatably mounted on this rack 11, one roller supporting pin 17 is implanted in each disc 12, and rollers 13 are rotatably mounted on the roller supporting pins 17 through bearings 14, respectively. These three discs 12 are arranged at intervals of two third of a lead of the passive rack 11 and meshed with each other through an intermediate gear 15 and an input gear 16 so that phase difference among the roller supporting pins 17 of the discs 12 may be 120 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectilinear motion mechanism which is used in, for example, an industrial robot, a transfer device or the like and converts a rotary motion into a linear motion.

[0002]

2. Description of the Related Art Conventionally, as a device for converting a rotational motion into a linear motion, for example, as shown in FIG. 1, a rack 2 having a large number of teeth 2a formed on the side surface of a linear member, and the rack 2 A rack and pinion mechanism including a pinion 1a (gear) having a large number of meshing teeth 1a is known. Further, as shown in FIG. 2, a rack 3 having corrugated teeth 3a
There is known a pin gear device including a pin gear 4 in which a large number of pins 4a meshing with the rack 3 are planted in a disc.

[0003]

In the conventional linear motion mechanism as described above, the rack is caused by the slip between the tooth surfaces of the rack and the pinion or the slip between the tooth surface of the rack and the pin on the disk. And there is a problem of wear of the tooth surface of the pinion.

Further, one tooth of the pinion or one of the discs
Since the pins of the book mesh with the teeth of the rack, there is a problem that the backlash between the rack and the pinion and the backlash between the rack and the pin of the disk are large, and the transmission efficiency is reduced.

Further, in the above-described pin rack structure, it is necessary to implant four or more pins on the disk due to the structure, and on the other hand, if the pin thickness is thin in order to mesh the rack teeth with the pins. There is no choice but to avoid the problem that a large load cannot be transmitted.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rectilinear motion mechanism having a small backlash and capable of withstanding a large load in view of the problems of the conventional device as described above.

[0007]

In the present invention, the above object is achieved by a passive rack having a corrugated tooth profile, three discs which are arranged to be rotatable at a predetermined interval while maintaining a predetermined phase difference, and This is achieved by a linear motion mechanism characterized by comprising one pin arranged eccentrically from the center of rotation of the disk and a roller rotatably supported by the pin via a bearing.

[0008]

In the present invention, three disks are provided, and one pin is arranged on each disk, so that the pin diameter can be increased and a large load can be endured.

Further, since the roller is rotatably supported by the pin via the bearing and the pin and the wave shape of the passive rack are rolled and transmitted, abrasion resistance and transmission efficiency can be improved.

[0010]

The present invention will be described in detail below with reference to the accompanying drawings. FIG. 3 shows a perspective view of an embodiment according to the present invention, in which a part of the cover part is removed. In FIG. 3, a case or main body 10 having a rack portion is fixedly supported on an inner wall thereof, and a linear rack support 11 is supported via a slide bearing 9 so as to be linearly interlockable with the case or main body 10. A corrugated member 11 a is formed on the surface of the passive rack 11.
The tooth profile 11a on the surface of the passive rack 11 has a trochoid curve or a cycloid curve as shown in FIG.

In FIG. 3, three disks 12 are rotatably provided on the side of the passive rack 11 so that the case or body 10 can be rotated.
Is supported by the toothed surface 12a on the peripheral surface of the disk 12.
The adjacent discs 12 are formed in the intermediate gear 1 rotatably supported by the case or the main body 10.
5 and the input gear 16, the three discs rotate in the same direction.

Each disk 12 is provided with one roller support pin 17 with the same eccentricity from the center of rotation.

The roller supporting pin 17 of each disk is
The roller 13 is rotatably supported via a bearing 14. The adjacent disks 12 are arranged such that the centers thereof are separated by a distance of 2/3 of the lead L (see FIG. 4) of the passive rack 11, and further these three disks 1
The second pins 17 each have a phase difference of 120 °.

When the input gear 16 is rotated, the three disks 12 directly meshing with the input gear 16 and indirectly through the intermediate gear 15 are in the opposite direction to the input gear 15 and all the disks 12 are Disk 1 rotates in the same direction
A roller 13 provided on the second gear meshes with the tooth profile of the passive rack 11 to cause the passive rack 11 to move linearly. At this time, the roller 13 and the tooth profile of the passive rack 11 are in rolling contact with each other.

[0015]

According to the present invention, three disks are provided, and one pin is arranged on each disk, so that the pin diameter can be increased and a large load can be endured.

Further, since the roller is rotatably supported by the pin through the bearing and the pin and the wave shape of the passive rack are rollingly transmitted, abrasion resistance and transmission efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a conventional rack and pinion mechanism.

FIG. 2 is a plan view showing a conventional pin rack device.

FIG. 3 is a perspective view showing a state in which a cover of the embodiment of the present invention is removed.

FIG. 4 is a diagram illustrating a tooth profile of the rack of the present invention.

[Explanation of symbols]

 11 Passive rack 12 Disk 13 Roller 14 Bearing

Claims (1)

[Claims] 1. A passive rack having a wavy tooth profile, three disks rotatably arranged at a predetermined interval while maintaining a predetermined phase difference, and each disk is eccentric from a rotation center of the disk by a predetermined amount. Rectilinear motion mechanism, which comprises a single pin and a roller rotatably supported by the pin via a bearing.