JPH0529574Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a ball screw used particularly in vacuum equipment, space equipment, high-temperature equipment, etc.

[Conventional technology]

Ball screws are precision screws in which a ball is inserted into a spiral hole formed by a spiral groove on the screw shaft and a spiral groove on the inner circumferential surface of the nut, converting the rotational movement of the screw shaft into linear movement of the nut. It's a screw. Some ball screws are used in equipment that cannot use lubricants such as lubricating oil or grease, such as vacuum equipment. In ball screws that cannot use such lubricants, layered solid lubricants whose surfaces are treated with lubricating metals, molybdenum disulfide, etc. are used to reduce the frictional resistance at the contact points between component parts. For example, as proposed in Utility Model Publication No. 19746, a coating layer is formed on the surface of the ball, the surface of each spiral groove of the male and female threaded member on which the ball rolls, or the surfaces of both the ball and the spiral groove. A method characterized by forming a phosphate film of several microns, or as proposed in Utility Model Application Publication No. 128956 of 1982, a film characterized by forming a phosphate film of several microns on at least one surface of the screw shaft, nut, and ball. There is a method characterized in that an intermediate layer film of a metal whose solubility with adjacent metals is greater than the solubility between the material metal of the component and gold or silver is formed by ion plating.

[Problem that the invention attempts to solve]

As mentioned above, various attempts have been made to apply ball screws to devices in which lubricants such as lubricating oil and grease cannot be used, but there is currently no definitive solution. For example, when it comes to applications in vacuum equipment, balls with Ag ion plating will have an extremely short lifespan if exposed to the atmosphere, and if they are exposed to corrosive gases or high-temperature atmospheres, they will not last long. It can be said that there are almost no products that can withstand use for a long period of time.

This invention was made in view of these problems, and its purpose is to provide a ball screw that can be applied to equipment in which lubricant cannot be used and that can also be used in a vacuum or in the atmosphere.

[Means for solving problems]

That is, in order to solve the above problems, this invention provides a ball screw consisting of a nut having a screw shaft and a circular tube, and a ball interposed between the screw shaft and the helical groove of the nut. The nut is made of stainless steel, and the ball is made of carbon, which has a hardness higher than that of the stainless steel. Further, the material of the circular tube is fluorine-based resin or stainless steel, and the material of every other ball is stainless steel, and the material of the balls between them is carbon with a negative dimension.

[Effect]

Carbon has considerable hardness and low frictional resistance, and stainless steel has corrosion resistance, so the contact surfaces between the parts will not stick to each other or dissolve. Therefore, overall frictional resistance is reduced and lubricity is improved. In addition, since fluorine-based resin has low frictional resistance, it contributes to improved lubrication between the circular tube and the ball, and when the ball comes into contact with the circular tube, the fluorine-based lubricating component is transferred, further lubrication. This will improve performance.

〔Example〕

Specific embodiments of this invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a ball screw according to this invention. In this figure, 1 is a screw shaft, and the screw shaft 1 has a spiral groove 1a formed therein. Reference numeral 2 denotes a nut, and the nut 2 also has a spiral groove 2a formed therein. 3
A is a ball, and the ball 3A has a spiral groove 1a formed in the screw shaft 1, as shown in FIG.
and a spiral groove 2a formed in the nut 2. 4 is a circular tube, and the circular tube 4 is a tube that connects two holes (not shown) bored at a predetermined interval in the tangential direction of the spiral groove 2a formed in the nut 2. be. That is, the ball 3A is moved between the circular tube 4 and the spiral hole 5 by the relative movement between the screw shaft 1 and the nut 2.
It will be transferred through a circulation path consisting of.

In the ball screw configured as above,
The material of the screw shaft 1 and the nut 2 is stainless steel, and the material of the ball 3A is carbon.
For example, use glassy carbon. Further, in this case, the hardness of the ball 3A using carbon is determined to be 1.5 times or more harder than stainless steel on the Vickers hardness. Further, if the circular tube 4 is made of a fluororesin, for example, polytetrafluoroethylene, the frictional resistance is extremely small, so the fluororesin component contributes to lubrication.

Next, FIG. 3 is a cross-sectional view in the horizontal direction with respect to the screw shaft 1. As shown in this figure, in the combination of the components of the ball screw, the screw shaft 1 and the nut 2
The material of is stainless steel, and every other ball is a stainless steel ball 3B, and the balls in between may be carbon balls 3A' with a negative dimension. In this case, among the balls arranged every other time, the carbon balls 3A' have a small diameter and therefore serve as spacers.

If the materials of each component of the ball screw according to this invention are configured as described above, carbon has considerable hardness and low frictional resistance, and stainless steel has corrosion resistance, so it is possible to make contact between each component. The surfaces do not stick to each other, reducing overall frictional resistance and improving lubricity.

[Effect of idea]

Since the ball screw according to this invention has the structure described in detail above, it can be used without lubrication regardless of whether it is in a vacuum or in the atmosphere. In addition, if the circular tube is made of stainless steel, it can be used even at high temperatures of over 200 degrees Celsius, and if stainless steel such as SUS630 is used, it can be used underwater, providing an extremely superior ball screw. You can.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the ball screw according to this invention, Fig. 2 is an enlarged view of the helical hole formed by the helical groove of the screw shaft and the nut, and the ball portion inserted in this helical hole. FIG. 3 is a lateral cross-sectional view of the shaft of the ball screw according to the invention. 1... Screw shaft, 1a... Spiral groove, 2... Nut, 2a... Spiral groove, 3A... Ball (carbon), 3B... Ball (stainless steel), 4... Circular tube, 5... Spiral hole.

Claims (1)

[Claims for Utility Model Registration] (1) A ball screw comprising a nut provided with a screw shaft and a circular tube, and a ball interposed between the screw shaft and the helical groove of the nut, in which the screw shaft and the nut A ball screw characterized in that the material is stainless steel, and the material of the balls is carbon having a hardness higher than that of the stainless steel. (2) The ball screw according to claim 1, wherein the material of the circular tube is a fluorine-based resin. (3) The ball screw according to claim 1, wherein the material of the circular tube is stainless steel. (4) The ball screw according to claim 1, wherein every other ball is made of stainless steel, and the balls between the balls are made of carbon having a negative dimension.