JP2000271739A - Screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw device long in service life of the device, and excellent in maintainability. SOLUTION: In the screw device to convert the rotational motion of a screw shaft 2 into the linear motion of a screw nut 1 to be screwed to the screw shaft, the screw nut is formed of a steel material, and a core portion 12 is formed of the steel material, and a threaded portion 11 is formed of a non-ferrous metal overlay welding material softer than the material of the screw nut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw device, and more particularly, to a screw device for converting a rotational movement of a screw shaft into a linear movement of a screw nut screwed onto the screw shaft.

[0002]

2. Description of the Related Art Conventionally, generally, in a screw device, a screw shaft (hereinafter simply referred to as a shaft) is generally used.
Is made of a steel material, and the screw nut (hereinafter also simply referred to as a nut) is made of a non-ferrous metal material such as a copper alloy.

[0003]

For example, when a work head is mounted on a screw nut screwed onto a screw shaft and the shaft is rotated, the work head performs a work involving a linear reciprocating motion. The threaded portion of the nut (nut threaded portion) contacts the threaded portion of the shaft (shaft threaded portion) entirely and constantly, but the shaft threaded portion partially and intermittently contacts the nut threaded portion. Therefore, the nut is made of non-ferrous metal material such as copper alloy,
In a conventional screw device in which the shaft is made of a steel material, the non-ferrous metal material such as a copper alloy is softer than the steel material. Also, in the conventional screw device, even if you try to check the degree of wear of the nut screw part, the nut is screwed to the shaft over the entire screw part,
Since there is no externally exposed portion in the nut screw portion, the width and height of the screw thread cannot be measured for checking the degree of wear, and there is a problem that maintenance is poor.

[0004] Therefore, an object of the present invention is to provide a screw device having a long device life and excellent maintainability.

[0005]

The present invention relates to a screw device for converting a rotary motion of a screw shaft into a linear motion of a screw nut screwed to the screw shaft, wherein the screw nut is made of a steel material; Is a screw device characterized in that a shaft portion is made of a steel material and a screw portion is made of a non-ferrous metal overlay material softer than the screw nut.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the magnitude relationship of the hardness of the threaded portion between the shaft and the nut is reversed from that of the prior art. That is, the shaft screw portion where the contact was partially or intermittently was set to the soft side, and the nut screw portion where the contact was entirely or constantly set to the hard side. As a result, the contact on the soft side becomes “intermittent” instead of “constant”, so that the contact time on the soft side is shortened (the chance of wear is reduced) and the life of the screw device is extended.
Further, since the soft side is formed as a thread portion in which the contact is "partial" instead of "whole", that is, a thread portion (shaft thread portion) having an observable non-contact (non-concealing or exposed) portion, wear is reduced. The progress can be confirmed, and the maintainability is improved.

As the nut material, a steel material is optimal from the viewpoints of strength, abrasion, and economy, and was therefore selected. In the nut, since there is no particular need to use different materials for the threaded portion and the other portions, the entire nut is made of a steel material. On the other hand, the shaft has a thread portion that is softer than the nut as described above. As the soft material, a non-ferrous metal material conventionally used as a nut material can be used. However, any non-ferrous metal material may be used, and its hardness must be smaller than that of the nut material of the present invention. Further, in the shaft, if the shaft portion is made of the same soft non-ferrous metal material as that of the screw portion, the strength is insufficient. That is, in the present invention, the shaft has a hard shaft center covered with a threaded portion made of a soft non-ferrous metal material.
It is necessary to have a layer structure. And as this coating method, the overlay welding method is suitable. Therefore, in the present invention, the material of the shaft screw member is limited to the non-ferrous metal overlay material softer than the nut.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is an overall side view showing the screw device of the embodiment, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is an axial sectional view showing a detailed structure of the nut screwing portion in FIG. As shown in these drawings, in the embodiment, a screw nut (nut) 1 is screwed into a screw shaft (shaft) 2 including a shaft portion 12 and a screw portion 11 forming an outer layer of the shaft portion 12.
A shoe 8 which rotatably supports both ends of the shaft 2 with a bearing box 4 via a bearing 3 and slidably engages the nut 1 with a slide guide 9 arranged parallel to the shaft 2.
It is constituted by joining. In FIG. 3, L2
Is the length of the shaft screw portion, L1 is the length of the nut screw portion, d is the thickness of the shaft screw portion, and L2 / L1 = 18.

When the shaft 2 is rotated by the motor 5 in the direction shown by the arrow 7, the nut 6 screwed to the shaft 2 reciprocates linearly in the direction shown by the arrow 6 along the slide guide 9 via the shoe 8. . One nut is S
The hardness was adjusted to Hs50-60 by surface quenching after forming. Shaft 2 shaft center 12
The material was SUS420J2, and the hardness was adjusted to Hs40 to 45 by surface quenching after forming. The material of the thread part 11 of the shaft 2 is Al: 10 wt%, Fe: 1.8 wt%, Ni: 2 wt%
%, Mn: 1.9 wt%, and a balance of Cu was formed into a copper alloy, which was overlaid on the surface of the shaft 2 and thread-cut after welding to form a threaded portion 11 having a hardness of Hs 26 to 30. .

[0010] A grinding wheel for grinding a rolling roll is attached to the nut 1 of the embodiment, and this is used for a rolling roll grinding operation. The nut 1 is made of the copper alloy (Hs 26 to 30) and the shaft 2
The whole was compared with the conventional one made of SUS420J2 (Hs50-60). As a result, in the example, the shaft maintenance and overburden / thread cutting repair cycle due to the shaft wear (the nut is hardened so that the nut wear does not progress) is based on the conventional nut wear (the shaft is hard and the shaft wear does not progress). The period was extended to approximately L2 / L1 times, that is, the life of the device was greatly extended. In addition, by making the shaft side with the exposed screw part soft, the width and height of the screw thread can be measured to check the degree of wear,
Maintainability has been significantly improved.

[0011]

As described above, according to the present invention, there is an excellent effect that a screw device having a long service life and excellent maintenance can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall side view showing a screw device of an embodiment.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an axial sectional view showing a detailed structure of a nut threaded portion in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw nut (nut) 2 Screw shaft (shaft) 3 Bearing 4 Bearing box 5 Motor 6 Arrow (Nut moving direction) 7 Arrow (Shaft rotating direction) 8 Shoe 9 Slide guide 11 Screw part 12 Shaft core

Continuing from the front page (72) Inventor Takaaki Ishikawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (72) Inventor Koichi Uemura 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Company Chiba Works

Claims (1)

[Claims] 1. A screw device for converting a rotary motion of a screw shaft into a linear motion of a screw nut screwed into the screw shaft, wherein the screw nut is made of a steel material, and the screw shaft is
A screw device, wherein a shaft portion is made of a steel material and a screw portion is made of a non-ferrous metal overlay material softer than the screw nut.