JPS61127966A - Static pressure screw feeding unit - Google Patents

Abstract

PURPOSE:To improve the thrust rigidity by making the male screw with porous material while bearing the thrust force functioning to male screw onto the receiving face spreading radially inward of the outer tube. CONSTITUTION:Male screw member 11 is made of metal or ceramic porous material and a spiral air feed groove 11a is made in the outercircumferential face while matching with thread pitch. Inward flange section 13a and inner threaded section 13b are provided respectively at the lower end and the upper end of the sleeve 13. In the sleeve 13, the lower endface of male screw member 11 will contact against the inner endface of inward flange section 13a to press the upper endface by means of a threaded ring 17 screwed to the inner threaded section 13b. The inner diameter at the endface of the inner flange section 14a of the outer tube 14 is shorter than the outer diameter of male screw member 11 to bear the thrust force of said member 11 onto the inner endface of the inner flange section 14a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a hydrostatic feed screw device used in high-speed feed mechanisms such as machine tools and measuring instruments.

[Prior Art] Conventional examples of static pressure feed screw devices include those shown in FIGS. 2 and 3. The static pressure feed screw device shown in this conventional example consists of a female screw member 1 made of a porous material and a male screw member 2 screwed into the female screw member 1. The female screw member 1 is
In the illustrated conventional example, a fan-shaped portion 1A is made of three porous materials.

It is vertically divided into IB and 1C, and each is adhered to a receiving plate 3 which is also vertically divided into three fan-shaped parts 3A, 3B, and 3G, and these fan-shaped parts 1A, 3A, and part I.
The female screw member 1 is assembled by fitting the parts B, 3B, and the parts IC, 3C into the outer cylinder 4, and tightly fitting the spacer 5 between the respective parts.

Fluid supply grooves 1a are formed along the screw leads inside the female threaded member 1 made of the above-mentioned porous material, and the respective fluid supply grooves 1a are communicated with each other by a communication path 1b.

A fluid supply port 6 communicating with the fluid supply groove 1a is formed in the receiving plate 3 and the outer cylinder 4. For example, high pressure air is supplied through the supply port 6 into one fluid supply @1a, and the communication path 1b
The fluid is distributed in all the fluid supply grooves 1a through the porous material and delivered to the bearing part of the male threaded member, thereby forming a bearing for supporting the male threaded member.

In addition, in the above conventional example, the fan-shaped portions 1A and 1B of the porous material
, 1C are received by boards 3A and 3B, respectively.

3C is shown, but if a highly rigid material such as ceramic is used as the porous material, the receiving plate can be omitted and the part can be made up of only three porous materials.

However, with such conventional static pressure feed screw devices,
A female screw member 1 made of a porous material is fixed to a receiving plate 3 or an outer cylinder 4 using an adhesive method such as an organic adhesive, and the rigidity of the entire system in the thrust direction varies greatly depending on the properties of the adhesive. In addition to the unavoidable disadvantage of a decrease in the temperature, there is also the risk that the bonded portion may peel off due to cleaning or the like during the processing process of the device.

[Objective and Summary of the Invention] The present invention aims to solve the problems of the prior art described above and provide a static pressure feed screw device with high axial thrust rigidity. The outer cylinder is provided with a thrust receiving surface that expands inward in the radial direction so that the thrust force is supported by the outer cylinder surrounding the outer circumference of the female screw, and the fixing means is installed with the female screw in contact with this thrust receiving surface. The female screw is restrained in the axial direction by the adhesive between the female screw and the outer cylinder or in the axial direction II! The thrust force of the female screw is directly received by the outer cylinder without friction, thus making it possible to increase the thrust rigidity to the material rigidity of the outer cylinder. In this case, good results can also be obtained in improving the alignment accuracy when assembling each segmented fan-shaped part.

[Embodiment] FIG. 1 shows an embodiment of the present invention, and here, in order to avoid complication of the drawing, only the female screw structure removed from the male screw is shown in a sectional view.

In FIG. 1, the female screw member 11 is an integral body made of a porous material such as metal or ceramic, and has a spiral air supply groove on its outer circumferential surface in accordance with the screw pitch. 1aS is provided. The outer circumferential surface of the female screw member 11 is lined with a sleeve 13 made of steel or the like, and the sleeve 13 is provided with an inner flange 13a at the lower end and an inner circumferential threaded section 13b at the upper end. Inside the sleeve 13, the female screw member 11 has a screw ring 17 whose lower end surface is in contact with the inner end surface of the inner flange portion 13a, and whose upper end surface is screwed into the inner peripheral thread portion 13b.
is forced by. Preferably female screw member 1
1 and the sleeve 13, an adhesive is applied to the contact portion of their peripheral surfaces to integrate them.

The sleeve 17 and the female screw member 11 are thus integrated and are roughly installed inside the outer cylinder 14. The outer cylinder 14 has an inner flange 14a at the lower end, and the inner diameter of the tip surface of the inner flange 14a is smaller than the outer diameter of the female threaded member 11, so that the thrust force of the female threaded member 11 is transferred to the inner flange 14a. It is designed so that it can be supported on the inner end surface. The inner diameter of the outer cylinder 14 is slightly larger than the outer diameter of the sleeve 13, and the upper end surface of the contact portion between the two circumferential surfaces is welded or the like. Although not shown, another threaded ring that presses the upper end surface of the sleeve 13 in the same way as the threaded ring 17 may be screwed onto the upper end of the outer cylinder 14, and in this case, the welding described above is not necessary.

An air supply hole 16 is provided in the body of the outer cylinder 14 and the sleeve 13, and by supplying pressurized air from the air supply hole 16 into the air supply groove 11a, the porous holes in the female screw member 11 are filled. Static air is introduced into the inner surface of the female thread through the quality structure.

In the static pressure feed screw device of this embodiment having such a configuration, the female screw member 11 and the outer cylinder 14 are mutually restrained with the abutting portion in the axial direction, so that the distance between the circumferential surfaces of each other is limited. Relative support in the thrust direction between the female screw member and the outer cylinder can be achieved without relying on friction or adhesive force, and it is possible to increase the thrust rigidity to the rigidity of the outer cylinder material.

In the embodiment shown in FIG. 1, the female threaded member 11 is lined with the sleeve 13, but if the female threaded member 11 is made of a highly rigid material such as ceramic, the female threaded member 11 can be lined without using the sleeve 13. It is also possible to install it directly inside the outer cylinder.

In addition, in the example shown in FIG. 1, the female screw member 11 and the sleeve 13
Although the examples have been shown in which each is an integral part, it goes without saying that the present invention can be similarly applied to a three-part type as shown in FIG. It is also possible to improve the alignment accuracy of the arrangement position by making contact with the inner flange of the sleeve or outer cylinder.

[Effects of the Invention] As described above, according to the present invention, the female threaded member and the outer cylinder are supported relative to each other at the contact surfaces in the thrust direction, and the mutual axial restraint is achieved by tightening the screw ring. Since this is done by bonding or welding, the rigidity in the thrust direction is improved regardless of the adhesive strength between the two, and the porous material that constitutes the female screw member can be selected from a wide range of options without being limited by adhesive properties. This eliminates the need for alignment adjustment after assembly of the female screw member and the outer cylinder.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, FIG. 2 is an end view showing a conventional example, and FIG. 3 is a cross-sectional view taken along the line ■-■ in FIG. 11: Female screw member, 13 Ni sleeve, 13a: Inner flange, 14: Outer cylinder, 14a: Inner flange, 1
7: Screw ring.

Claims (1)

[Claims] 1. A static pressure feed screw device for converting rotational motion into linear motion, comprising: a female screw made of a porous material; an outer cylinder surrounding the outer circumference of the female screw; A fixing means for restraining the female thread in the axial direction with respect to the outer cylinder so that the thrust force acting relatively to the outer cylinder is supported by a thrust bearing surface provided on the outer cylinder that spreads inward in the radial direction. A static pressure feed screw device. 2. The static pressure feed screw device according to claim 1, wherein the fixing means includes a screw ring that presses and tightens the female screw against the thrust receiving surface. 3. The static pressure feed screw device according to claim 1, wherein the fixing means includes a welded portion between the female thread and the outer cylinder.