JPH04236845A - Ball screw mechanism - Google Patents

Abstract

PURPOSE:To increase an absolute amount of lubrication of a transition film without increasing the thickness of a solid lubricant film and to provide an increased life. CONSTITUTION:First and fourth bypass members 12 and 15, by which a circuit is formed at both ends of a nut 11, and contained balls 16a are formed of a solid lubricant. Third and fourth bypass members 13 and 14, contained balls 16b, a ball screw 10, and a nut 11 are formed of a metallic material and covered with a solid lubricant film to perform lubrication of a three-body transition film.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball screw mechanism suitable for use in extreme environments such as outer space and vacuum environments.

0002

[Prior Art] As is well known, in outer space, since the environment is almost a vacuum, it is difficult to lubricate the oil or grease used on the ground. A solid lubrication system using a solid lubricant such as molybdenum disulfide is adopted for the ball screw mechanism. Conventionally, this type of solid lubrication method involves forming a solid lubricant film by sputtering or plating a solid lubricant on the ball of a ball screw mechanism and the threaded part of the ball screw and nut, or by coating the ball with a solid lubricant. The solid lubricant film is then transferred into a solid lubricant film for lubrication.

However, in the above-mentioned solid lubrication type ball screw mechanism, in the former case, it is possible to form a relatively thin solid lubricant film, so that the gap that occurs in the threaded portion due to screw adjustment is relatively small. However, since the absolute amount of solid lubricant film that contributes to lubrication is small,
The problem was that it had a short lifespan. In addition, in the latter case, since the solid lubricant film is formed relatively thick, abrasion powder is likely to be generated due to wear and tear of the solid lubricant film, and gaps that may cause play in the threaded portion are likely to occur. Therefore, there was a problem that the lifespan was short.

[0004] As described above, in the conventional ball screw mechanism,
Since the absolute amount of solid lubricant film on the threaded joint is small and it easily generates wear powder, it has a short lifespan and is suitable for use in extreme environments such as space environments where maintenance and inspection work is difficult. It wasn't something I could enjoy.

[0005] This situation is not limited to the space environment, but also applies to extreme environments such as vacuum environments on the ground.

[0006]

[Problems to be Solved by the Invention] As stated above, the conventional ball screw mechanism has a short lifespan and is therefore unsatisfactory for use in extreme environments such as space environments where maintenance and inspection work is difficult. There was a problem.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a ball screw mechanism that has a simple structure, has a long service life, and is easy to handle.

[0008]

[Means for Solving the Problems] The present invention provides a screw groove in a nut that is screwed into a ball screw through a ball.
In a ball screw mechanism in which a bypass member is provided for each rotation to form one circuit, and the balls are circulated for each circuit via the bypass member, one circuit is configured at least on both end sides of the nut. The ball and bypass member are made of a solid lubricant, and the other balls, ball screw, and nut are made of a metal material and coated with a solid lubricant film.

[0009]

[Operation] According to the above structure, the ball screw and the nut are lubricated by a transfer film by the solid lubricant film of the threaded portion and the solid lubricant film of the balls, and the ball screw and the nut are provided with transfer film lubrication by the solid lubricant film of the threaded portion and the solid lubricant film of the balls, and one circuit of balls and bypasses formed of the solid lubricant. Transfer film lubrication is performed through the members, thereby performing transfer film lubrication by three-body lubrication. Therefore, wear and tear is relatively small, highly accurate transfer film lubrication is realized, and the life span is extended as much as possible.

0010

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a ball screw mechanism according to an embodiment of the present invention, in which a ball screw and nuts 10, 11 are shown.
are each made of a metal material, and the surface on the threaded portion side is subjected to a coating treatment such as a hollybdenum disulfide coating treatment to adhere a solid lubricant film. Among these, the nut 11 is fitted with first to fourth bypass members 12 to 15, which are called pieces and constitute a plurality of circuits, one circuit corresponding to one rotation of the thread groove. These first to fourth bypass members 12-
Reference numeral 15 communicates the thread groove for one rotation formed by the threaded portion of the ball screw 10 and the nut 11, and circulates and guides the balls 16a and 16b housed in the circuit to rotate the ball screw 10.
This allows adjustment of the screw engagement between the nut 11 and the nut 11.

The first and fourth bypass members 12 and 15 located at both ends of the nut 11 are made of a solid lubricant such as polytetrafluoroethylene (PTFE) resin, and the second and third bypass members 13 and 14 are formed of a metal material, and a solid lubricant film of molybdenum disulfide or the like is adhered to the surface thereof. In addition, a ball screw 10 and a nut 11
The balls 16a, 16b interposed therebetween are similarly made of a solid lubricant such as PTFE resin, and the balls 16a housed in one circuit closed by the first and fourth bypass members 12, 15 are made of a solid lubricant such as PTFE resin. 2 and 3rd bypass members 13, 14
The ball 16b accommodated in the circuit closed by the ball 16b is made of a metal material, and a film of solid lubricant such as the above-mentioned molybdenum disulfide is deposited on the surface of the ball 16b.

[0013] Note that the first to fourth bypass members 1
As shown in FIG. 2, 2 to 15 are screws of the nut 11 so as to constitute one circuit corresponding to one rotation of the screw groove, with a predetermined number of balls 16a and 16b accommodated in the screw groove of the nut 11, respectively. The balls 16a and 16b inserted and housed in predetermined positions are circulated within the circuit to realize threading adjustment between the ball screw 10 and the nut 11.

In the above configuration, when the ball screw 10 and the nut 11 are rotated, the balls 16a, 16b
circulates in a circuit formed by the first to fourth bypass members 12 to 15 to adjust the threading of the ball screw 10 and the nut 11. At this time, the first and fourth bypass members 12,
15 performs transfer film lubrication between the ball screw 10 and the threaded portion of the nut 11 in conjunction with the circulation of the balls 16a. At the same time, other second and third bypass members 13, 14
The ball 16b, the ball screw 10, and the nut 11 in the circuit formed by the above are transferred film lubricated with their respective solid lubricant films, and so-called three-body transfer film lubrication is performed here.

[0015] In this way, the above-mentioned ball screw mechanism has the first and fourth bypass members 12, 15 constituting one circuit at both ends of the nut and the ball 16a accommodated in the ball 16a made of solid lubricant. 4 bypass members 13 and 14, a ball 16b accommodated, a ball screw 10, and a nut 1
1 was formed of a metal material and a solid lubricant film was applied thereto. According to this, the ball screw 10 and the nut 11
transfer film lubrication is performed by the solid lubricant film on the threaded portion, the solid lubricant film on the second and third bypass members 13, 14, and the ball 16b, and the first and fourth bypass members 12, 15 and its ball 16a performs transfer film lubrication, so that wear and tear is relatively small, highly accurate transfer film lubrication is realized, and its life can be extended.

In the above embodiment, the first and fourth bias members 12 and 15 located at both ends of the nut 11 and the ball 16a are made of solid lubricant, but at least these should be made of fixed lubricant. It is also possible to similarly form the other second and third bias members 13 and 14 and the ball 16b with a solid lubricant.

Further, in the above embodiment, the number of circuits is four, but the present invention is not limited to this number and can be applied.

Therefore, it goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made without departing from the gist of the invention.

[0019]

As described in detail above, according to the present invention, it is possible to provide a ball screw mechanism that has a simple structure, has a long life, and is easy to handle.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a ball screw mechanism according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of balls constituting one circuit in FIG. 1;

[Explanation of symbols]

10... Ball screw, 11... Nut, 12 to 15... First
to fourth bypass members, 16a, 16b...balls;

Claims (1)

[Claims] 1. A bypass member is provided in one rotation of a thread groove of a nut screwed into a ball screw via a ball to form one circuit, and the ball is connected to the ball screw for one circuit through the bypass member. In the ball screw mechanism, the balls and the bypass member constituting one circuit on at least both ends of the nut are made of solid lubricant, and the other balls, ball screw, and nut are made of metal material. A ball screw mechanism characterized by forming and coating a solid lubricant film.