JPS61248955A - Linear drive unit - Google Patents

Abstract

PURPOSE:To decrease back flash of a roller to a shaft to zero, according to the method wherein, in a linear drive unit used in NC lathes, a block body is supported in a manner that it is pressed against the peripheral surface of a shaft by dint of plural rollers. CONSTITUTION:A block body 22 is formed with two block segments 24 and 26, which are positioned facing each other with a shaft 20 therebetween. Slanted surfaces 28a, 28b, 30a, and 30b are formed on the two end wall surfaces of the block segment 24 in a manner to be inclined vertically to the peripheral surface of the shaft 20 and in the same direction to and at the same angle with the axis of the shaft 20. Slanted surfaces 30c are also respectively formed on both end surfaces of the block segment 26. Rotary rollers 32 are respectively secured on the slanted surfaces 28a-28c, 30a-30c by means of fixing bolts 34, and are rotated around their respective bolts 34. The two blocks 24 and 26 are fastened by means of fastening bolts 38 and 40, and the block body 22 is held on the shaft 20.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a linear drive unit.

(Prior art and its problems) In an NC lathe, etc., a linear drive unit as shown in Fig. 4 is used to precisely drive an NC table.
10 is used.

This linear drive unit 10 generally uses a ball screw.

In a device using such a ball screw, elastic deformation occurs at the contact point between the steel ball and the ball groove due to the axial load, resulting in buff crash, that is, backlash. In order to minimize the amount of elastic displacement in response to the above-mentioned axial load and improve rigidity, a preload is generally applied.

However, a linear drive unit using such an adjustment mechanism is extremely expensive.

Precise machining of the ball groove on the screw shaft to match the size of the steel ball is also troublesome.

Furthermore, since a threaded shaft is used, in order to change the running speed of the traveling body that is threaded onto the threaded shaft, it is necessary to change the rotational speed of the drive motor that rotates the threaded shaft each time, or to provide a transmission device. There is a problem with this.

(Summary of the Invention) The present invention has been made to solve the above problems, and its purpose is to provide a simple structure that can be manufactured at low cost, zero backlash, and accurate drive. The purpose of the present invention is to provide a linear drive unit in which a shaft and a block body are moved back and forth relative to each other, and the block body is configured to sandwich the shaft. The block body is formed into a plurality of opposing block pieces, each of which has a circumferential surface protruding inward from the inner surface of the block piece, a rotating surface perpendicular to the shaft circumferential surface, and whose center of rotation is aligned with the shaft. Three or more rollers that are inclined in the same direction and at the same angle with respect to the axis of the shaft when viewed from the front are provided surrounding the shaft, and the block piece is tightened so that the outer circumferential surface of each roller is pressed against the circumferential surface of the shaft. It is in the place where the means are set up.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In FIGS. 1 and 2, 20 is a shaft, which is rotatably attached to a suitable drive motor (not shown) about its axis.

22 is a block body, and in the illustrated embodiment, it is divided into two parts.
It is formed into two block pieces 24 and 26, which are positioned opposite to each other with the shaft 20 in between.

On both end walls of the block piece 24, there are two inclined surfaces 28a that are perpendicular to the shaft peripheral surface and inclined in the same direction and at the same angle with respect to the axis of the shaft 20 (front shape at each rotational position). , 28b, and inclined surfaces 30a, 30b are provided, respectively.

Also, both end faces of the block piece 26 are perpendicular to the shaft surface and inclined in the same direction and at the same angle with respect to the axis of the shaft as the above-mentioned inclined plane (front shape at each rotation position).
, and an inclined surface 30c are provided, respectively.

32 is each of the above-mentioned inclined surfaces 28a, 28b, 28c, 30a,
30b and 30c with fixing bolts 34 perpendicular to the inclined surface, and are rotating rollers that rotate around the fixing bolts 34. Note that the rotating roller 32 can also be used by using a bearing and fixing the inner ring of the bearing with a fixing bolt 34.

Each rotating roller 32 has the same diameter, and its peripheral surface protrudes inward from the inner surface of each block piece 24, 26.

38.40 is a tightening bolt, and both block pieces 24
．． Tighten 26.

By tightening the tightening bolts 38 and 40, both block pieces 24 and 26 are brought closer together, and the shaft 20 is tightened by the circumferential surface of each rotating roller 32 protruding inward from the inner surface of the block piece, so that the block body 22 is placed on the shaft 20. is maintained.

The present invention is configured as described above.

As is clear from the above configuration, each of the six rollers 32 is in contact (point contact) with the circumferential surface of the shaft 20 on six threaded lines having the same pitch, directly facing the threaded lines. By appropriately adjusting the tightening force of the tightening bolts 38 and 40, the block body 22 is supported by the six rollers 32, and its frictional resistance resists the load in the thrust direction of the shaft.

By connecting the block body 22 to a movable body such as an NC table of an NC lathe that is movable while being supported by a suitable guide, and rotating the shaft 20, the block body 22 is fed by the movable body. can be driven back and forth.

In addition, if the above-mentioned bearing is used for the roller 32, even if the bearing 36 itself has backlash, the bearing is pressed against the circumferential surface of the shaft 20 by the tightening bolt 38, 40, so that the bearing shaft 20
The backlash can be reduced to almost zero.

It goes without saying that the block body 22 may be connected to a suitable rotation mechanism and rotated to move the shaft 20 forward and backward.

Further, by changing the diameter of the roller 32 attached to the block body 22, the relative speed between the block body 22 and the shaft 20 can be changed. The roller 32 can be easily replaced by removing the fixing bolt 34, and then readjusting the tightening of the roller 32 using the tightening bolts 38, 40.

FIG. 3 shows another embodiment.

In this embodiment, the small block pieces 42, 44 and 46, 48 each having an inclined surface to which each of the rollers 32 is attached are attached to the end face of each block piece 24, 26 so as to be replaceable with fixing bolts (not shown), etc. It is fixed by

Small block pieces 42, 44 and 46 have various inclined surfaces and rollers 32 are attached to these inclined surfaces.
．． 48 are prepared in advance, and small block pieces 42, 44 and 46, 48 having a predetermined slope according to the purpose are prepared.
By attaching and using the block pieces 24 and 26, the relative pitch (lead) between the block body 22 and the shaft 20 can be set variously. Of course, by preparing rollers 32 of various diameters in the same manner as described above, the relative speed between the block body 22 and the shaft 20 can be set more finely.

In each of the above embodiments, the block body 22 is provided in two block pieces 24 and 26, but the present invention is not limited to this.
Of course, it is also possible to use more than one piece.

Further, rollers 3 provided on both end faces of the block body 22
2 is a plurality of three or more pieces sufficient to hold the shaft 20.

(Effects of the Invention) As described above, according to the linear drive unit of the present invention, the block body is supported with a plurality of rollers pressed against the circumferential surface of the shaft. The process of precisely finishing the ball can be omitted and can be provided at a low cost.

In addition, since the block body is divided into multiple pieces and the rollers are placed in pressure contact with the shaft using tightening means, rollers with different diameters can be easily replaced and used, and the relative speed between the shaft and the block body can be easily adjusted. It can be converted to .

Since the roller is pressed against the shaft by the tightening means, the backlash of the roller against the shaft can be reduced to almost zero, and a moving object such as an NC table of an NC lathe can be driven accurately without rattling. .

Since the small block piece to which the roller is attached is configured to be separably fixed from the block piece main body, it is possible to easily change the lead by replacing the small block piece to which the roller is attached at various angles. It is very effective.

Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

[Brief explanation of drawings]

FIG. 1 is a front view schematically showing a linear drive unit according to the present invention, and FIG. 2 is a side view thereof. FIG. 3 is a front view showing another embodiment. FIG. 4 is an explanatory diagram showing a conventional example. 10... linear drive unit,

Claims (1)

[Claims] 1. In a linear drive unit in which a shaft and a block body move forward and backward relative to each other, the block body is formed into a plurality of block pieces facing each other with the shaft in between, and both end surfaces of the block body respectively, the circumferential surface protrudes inward from the inner surface of the block piece, the rotating surface is perpendicular to the shaft circumferential surface, and the center of rotation is inclined in the same direction and at the same angle with respect to the axis of the shaft when viewed from the front of the shaft. Three or more rollers are provided surrounding the shaft, and the outer circumferential surface of each roller is pressed against the circumferential surface of the shaft,
A linear drive unit characterized in that a means for tightening the block piece is provided. 2. The linear drive unit according to claim 1, wherein the rollers are replaceable with rollers of various diameters. 3. In a linear drive unit in which a shaft and a block body are moved back and forth relative to each other, the block body is removably fixed to a plurality of block pieces facing each other with the shaft in between, and to both ends of each block piece. Each of the end faces of this block body has a circumferential surface protruding inward from the inner surface of the block piece, a rotating surface perpendicular to the shaft circumferential surface, and a rotation center thereof when viewed from the front of the shaft. Three or more rollers that are inclined in the same direction and at the same angle with respect to the axis of the shaft are provided surrounding the shaft, and the outer circumferential surface of each roller is pressed against the circumferential surface of the shaft,
A linear drive unit characterized in that a means for tightening the block piece is provided.