JP2011183415A - Method for manufacturing lead screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead screw manufacturing method for manufacturing lead screws rich in productivity and having low manufacturing cost. <P>SOLUTION: In the lead screw manufacturing method, a hoop material 1 is prepared (Fig.1(A)), the hoop material is fed in its longitudinal direction to continuously form a seam tube 2 by the involution-drawing (Fig.1(B)), and the seam tube 2 is welded along a seam 2a to form a weld part 2b (Fig.1(C)). The seam tube is drawn in its longitudinal direction to reduce the diameter of the tube (Fig.1(D)), and the diameter-reduced tube 3 is cut to obtain a tube 4 of the predetermined dimension (Fig.1(E)). A form-rolled male screw part 5a is formed on an outer surface of the tube 4 of the predetermined dimension to obtain a lead screw tube 5 (Fig.1(F)). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lead screw shaft used for a stepping motor or the like, and more particularly, to a method for producing a lead screw for screw-feeding a nut or the like in a separately assembled lead screw shaft.

  The structure of the separately assembled lead screw / shaft disclosed in Patent Document 1 is that the lead screw (guide male screw) and the motor shaft (rotary shaft) are separate, and the motor is attached to the end of the lead screw opposite to the motor shaft. A bearing end portion having a smaller diameter than the shaft is formed by cutting, and a motor shaft fitting portion projecting in the axial direction is formed by cutting on the motor shaft side end portion of the lead screw. A motor shaft fitting hole is drilled, and the end of the motor shaft is press-fitted and fixed thereto. Since a motor shaft having an outer diameter smaller than the outer diameter of the lead screw can be used, friction loss at the bearing portion of the motor shaft can be reduced. Moreover, compared with the manufacturing method which forms a thin motor shaft part integral with a lead screw by cutting, the sliding loss and noise generation accompanying the surface roughness of the external thread part by cutting can be suppressed.

JP 2007-151237 A (FIGS. 6 and 7)

  However, in the manufacture of the lead screw in the separate assembly type lead screw / shaft described above, cutting to form a bearing end portion and a motor shaft fitting portion for the stainless steel thin rod is essential before thread rolling, In addition, even after thread rolling, drilling of the motor shaft fitting hole is required, so that the mass productivity is poor and the manufacturing cost of the lead screw itself is high.

  Therefore, in order to solve the above-described problems, an object of the present invention is to provide a method for manufacturing a lead screw that can provide a lead screw that has high mass productivity and low manufacturing costs.

  In the lead screw manufacturing method according to the present invention, a hoop material is continuously drawn and drawn while being fed in the longitudinal direction thereof, and a seam tube is continuously formed. The seam tube is welded along the seam and then stretched in the tube length direction. It is characterized in that a diameter-reduced tube is cut to obtain a tube of a predetermined size, and then a rolled male screw portion is formed on the outer surface of the tube of the predetermined size.

  Until a tube with the specified dimensions is obtained, the forming (sealing and drawing) process, seam welding process, pipe stretching process and pipe cutting process can be realized by line work, and it has excellent mass productivity and the forming (contracting and drawing process). Since the accuracy of the outer diameter of the pipe can be controlled in the pipe extension process, unlike the cutting process, it is not necessary to add centerless polishing and can be directly used for the rolling process. Therefore, a lead screw with a low manufacturing cost can be provided. In addition, because the external thread is rolled on the outer surface of a tube with a hollow that penetrates, not only lateral distortion but also longitudinal distortion to the hollow side may occur due to the biting depth of the rolled-wheel external thread. The extension in the tube length direction at the time of rolling finish can be suppressed. In addition to this, the motor shaft can be inserted into the lead screw by press-fitting or adhesive application, and the hollow can be fitted longer as the motor shaft penetrates, and the concentricity and straightness between the lead screw and the motor shaft can be improved. And since it is a lead screw tube having a through-hole, it is possible to support the lead screw tube without touching the rolled male screw portion by inserting a jig pin from the end portion on the side opposite to the motor shaft, The press-fitting work of the motor shaft becomes easy.

  It is desirable to chamfer the outer peripheral sides of both ends of a pipe having a predetermined dimension between the pipe cutting process and the thread rolling process. If chamfering (outer taper surface) is formed on the outer peripheral sides of both ends, it is possible to suppress the crests of the outermost threaded male threaded portion from becoming thin and crushing in the thread rolling process.

  Moreover, it is desirable to chamfer the inner peripheral side of both ends of a pipe having a predetermined dimension between the pipe cutting process and the thread rolling process. When the motor shaft is inserted halfway through the lead screw and left hollow, the steel balls of the pivot bearing can be stably stored in the chamfers (inner taper surfaces) on the inner peripheral sides of both ends.

  According to the present invention, a pipe having a predetermined size is obtained in advance by a forming (rolling drawing) process, a seam welding process, a pipe extension process, and a pipe cutting process using a hoop material, and this is then subjected to a screw rolling process. Therefore, it is possible to obtain a lead screw with high productivity and low manufacturing cost.

(A)-(F) are perspective views which show the workpiece | work of each process of the manufacturing method of the lead screw which concerns on the Example of this invention.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1A, a lead screw manufacturing method of this example is prepared by first preparing a strip-like long stainless steel hoop material 1 and feeding the stainless steel hoop material 1 in the longitudinal direction. As shown in FIG. 5B, the sheet is drawn through a squeeze drawing die (not shown) and subjected to squeeze drawing (forming) to form the seam tube 2 continuously. Subsequently, as shown in FIG. 1 (C), the seam pipe 2 is welded along the seam (seam) 2a, and a welded portion 2b is applied. Then, as shown in FIG. The pipe 3 is formed in such a diameter that the welded portion 2b is not visible, and the pipe 3 is cut as shown in FIG. Then, the pipe 4 having a predetermined dimension is passed between a pair of rolling wheels (not shown) to obtain a lead screw pipe 5 having a rolling male screw portion 5a on the outer surface of the pipe 4. The outer diameter of the lead screw tube 5 of this example is 1.7 mm, for example, and its inner diameter is 0.8 mm.

  A motor shaft (not shown) is inserted into such a lead screw pipe 5 by press-fitting or adhesive application, thereby constituting a separately assembled lead screw shaft, which can be used as a small PM type stepping motor or the like. It is what is used.

  In the manufacturing method of the lead screw pipe 5 described above, until a pipe 4 having a predetermined size is obtained, the forming (rolling drawing) process of FIG. 1 (B), the pipe welding process of FIG. 1 (C), and the process of FIG. The pipe extension process and the pipe cutting process of FIG. 1 (E) can be realized by line work, and it is rich in mass productivity, and the forming (rolling drawing) process of FIG. 1 (B) and FIG. 1 (D). Since the accuracy of the outer diameter of the pipe can be managed in the pipe extension process, it is not necessary to add centerless polishing unlike the cutting process, and can be used for the rolling process in FIG. Therefore, the lead screw pipe 5 with a low manufacturing cost can be obtained.

  In addition, since the outer surface of the pipe having the hollow 5b penetrating is rolled, not only the lateral distortion but also the vertical distortion toward the hollow 5b can be caused slightly by the biting of the male thread portion of the rolling ring. It is possible to suppress the extension in the tube length direction.

  In addition, a motor shaft (not shown) can be inserted into the lead screw tube 5 by press-fitting or adhesive application, and the hollow 5b can be fitted longer as the motor shaft penetrates. Can improve concentricity and straightness. And since it is the lead screw pipe 5 which has a penetration hollow 5b as a separate assembly type lead screw shaft, a jig pin is inserted from the end on the side opposite to the motor shaft, and the lead screw pipe is not touched with the rolling male screw part. Therefore, the press-fitting work of the motor shaft to the end portion on the motor shaft side becomes easy.

  It is desirable to chamfer the outer peripheral sides of both ends of the pipe 4 having a predetermined dimension between the pipe cutting process of FIG. 1 (E) and the thread rolling process of FIG. 1 (F). If chamfering (outer taper surface) is formed on the outer peripheral sides of both ends, it is possible to suppress the crests of the outermost rolled male screw portion 5a from becoming thin and crushing in the screw rolling step. Moreover, it is desirable to chamfer the inner peripheral side of both ends of the pipe 4 having a predetermined dimension between the pipe cutting process and the thread rolling process. When the motor shaft is inserted partway through the hollow 5b and the hollow 5b is left, the steel balls (not shown) of the pivot bearing can be stably stored in the chamfers (inner tapered surfaces) on the inner peripheral sides of both ends.

DESCRIPTION OF SYMBOLS 1 ... Hoop material 2 ... Seam pipe 2a ... Seam (seam)
2b ... welded part 3 ... thinned pipe 4 ... predetermined pipe 5 ... lead screw pipe 5a ... rolled male thread 5b ... hollow

Claims (3)

A seam tube is continuously formed by entrainment drawing while feeding the hoop material in the longitudinal direction, the seam of the seam tube is welded, then stretched in the tube length direction to reduce the diameter, and the reduced diameter tube is cut. Then, after obtaining a pipe having a predetermined dimension, a rolled male screw portion is formed on the outer surface of the pipe having the predetermined dimension. 2. The lead screw manufacturing method according to claim 1, wherein chamfering is performed on both outer peripheral sides of the pipe having the predetermined dimension between the cutting step and the rolling step. . 3. The lead screw manufacturing method according to claim 1, wherein chamfering is performed on both inner peripheral sides of the pipe having the predetermined dimension between the cutting step and the rolling step. Lead screw manufacturing method.

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