JPH0775323A - Stepping motor - Google Patents

Abstract

PURPOSE:To provide a stepping motor, which is used for OA and AV equipments, cost of which is reduced and which has high accuracy and the small transmissibility of vibrations. CONSTITUTION:A hole 1c is formed in a coaxial manner with a rotor shaft 1b made of a metal in the longitudinal direction of a lead screw shaft 1a made of a resin, and the rotor shaft made of the metal is press-fitted lightly into the hole, thus giving a lead screw section elasticity, then obtaining a stepping motor, which has high accuracy and vibrations of which are lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor used for a lens driving device used for a video camera, a floppy disk head driving device, various OA equipment driving devices and the like.

[0002]

2. Description of the Related Art In recent years, as the equipment has become lighter, thinner, shorter, and smaller, the stepping motor for driving the same has also been downsized, and not only is the motor highly efficient and accurate, but it also has low vibration and low noise when mounted on the equipment. Is requested.

One of the key components that determines these performances is the lead screw shaft. Conventionally, a raw material of a lead screw shaft is generally a metal, particularly a raw material of stainless steel. Stainless steel is highly reliable because it has corrosion resistance and wear resistance, and for this reason it has a wide range of usage records. In addition, other materials for the lead screw include brass and surface-treated stainless steel.

Hereinafter, regarding the conventional stepping motor,
A description will be given with reference to the drawings. In FIG. 5, 1 is a metal lead screw shaft of a motor supported on one side by an impregnated bearing 2 and 3 is fixed to the motor case 5 with screws or the like to support the tip of the metal lead screw shaft 1 and a guide bar described later. An attachment plate for attaching 13 and 13 is a guide bar of the driven system 12, and is attached to the attachment plate 3 in parallel with the metal lead screw shaft 1. Reference numeral 11 is a guide pin for guiding the driven system 12 along the metallic lead screw shaft 1, and 14 is a metallic lead screw shaft 1.
It is a pivot bearing that supports the tip end portion through a hard ball, and is provided on the mounting plate 3 on the side opposite to the motor. The driven system 12 is brought into contact with the threaded portion of the metallic lead screw 1 via the guide pin 11 and moves axially along the guide bar 13 by the rotation of the metallic lead screw shaft.

[0005]

In such a conventional stepping motor, since the lead screw shaft is made of metal, it has high reliability, but has the following three problems.

First, since the elasticity of the metal lead screw shaft is very small, it is easy to directly transmit the vibration generated by the stepping motor to the FDD head, which is the driven system, the lens of the video camera or the like.

The second point is that the metal lead screw shaft has a limit in processing the surface roughness of the flank surface, which is the contact portion with the driven system, and the surface roughness of the flank surface causes vibrations in the driven system. There is a problem that it is transmitted.

The third point is that the lead screw pitch error is limited in machining, which directly affects the positional accuracy of the driven system.

The present invention solves the above problems, and an object of the present invention is to provide a stepping motor which is highly accurate, low cost, and resistant to vibration.

[0010]

In order to achieve this object, a stepping motor of the present invention is one in which a lead screw shaft is processed and made of resin, and the resin lead screw shaft is made of a metal rotor shaft of a motor main body. A hole that does not penetrate coaxially with or a cylindrical through hole is provided, and a metal rotor shaft is inserted into the hole as a core, or a resin lead screw shaft is integrally molded with a metal rotor shaft as a core. Processed,
This is a configuration to be created.

[0011]

According to this structure, since the lead screw shaft is made of resin, the shaft can have elasticity, and the transmission of the vibration generated by the stepping motor to the driven system can be reduced. In addition, by providing a hole that does not penetrate the resin-made lead screw shaft or a cylindrical through hole and inserting the metal rotor shaft as the core, bending and deflection of the lead screw part is reduced, and a highly reliable lead screw stepping motor is provided. can do. Further, by integrally molding the resin with the rotor shaft as the core to form the lead screw shaft, in addition to the above-described action, it is possible to achieve a pitch with high accuracy and less variation, and also to reduce surface roughness.

[0012]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a stepping motor, and FIG. 2 is an enlarged view of a lead screw shaft portion.

In FIGS. 1 and 2, reference numeral 1a denotes a lead screw shaft made by processing a resin, and a hole 1c which does not penetrate coaxially with the rotor shaft 1b is provided in the longitudinal direction thereof, and the hole 1c and the rotor shaft 1b are provided. And are fixed by light press-fitting. The depth of the hole 1c is 1.2 times or more as large as the press-fitting margin of the rotor shaft 1b. If the depth of the hole 1c cannot be 1.2 times or more, the air is vented from the lead screw shaft 1a made of resin or metal. It is provided on either of the manufactured rotor shafts 1b.

In the stepping motor constructed as described above, the elasticity of the lead screw portion can be changed by changing the resin material in accordance with the mass / inertia / reliability standard of the drive system. Transmission to the driven system can be minimized.

(Embodiment 2) FIG. 3 is an enlarged view showing a case where a rotor shaft penetrates a resin lead screw shaft.

Similar to the first embodiment, 1a is a resin lead screw shaft, and the rotor shaft 1 extends in the longitudinal direction.
A through hole 1d coaxial with b is provided, and the through hole 1d is fixed to the core rotor shaft 1b by light press fitting.

Since the rotor shaft 1b penetrates through the resin-made lead screw shaft 1a, the stepping motor configured as described above is not only the characteristic of the first embodiment but also strong against load and impact in the radial direction and highly reliable. The characteristic is obtained.

(Embodiment 3) FIG. 4 shows an embodiment in which a lead screw portion is integrally molded with a resin on a rotor shaft as a core. The rotor shaft 1b has one or more D cuts 1e or the entire lead screw portion, and serves to prevent slipping rotation between the rotor shaft 1b and the resin lead screw shaft 1a.

The resin lead screw shaft 1a is molded by inserting the rotor shaft 1b into a female screw die, molding the female screw so as to be coaxial with the external shape and the three-needle diameter of the female screw, and holding the rotor shaft 1b after the molding and rotating it. Try to pull it out of the mold. This leads the lead screw shaft 1
The outer diameter, flank surface, valley diameter, and other parts of a that require precision are smooth without joints due to molding. Since it is an integral molding, the surface roughness, pitch, etc. are better than those obtained in metal processing due to the molding conditions, mold processing accuracy, and optimum selection of molding materials.

In all of the above three embodiments, the processing of resin is performed, and the material cost and the processing cost can be reduced as compared with the processing of metal.

[0021]

As is apparent from the above embodiments, according to the present invention, by making the lead screw portion made of resin, it is possible to easily realize a high-precision stepping motor that is inexpensive and is less likely to transmit vibration to the driven system. Can be designed and produced.

[Brief description of drawings]

FIG. 1 is an overall plan sectional view of a stepping motor according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of only a shaft portion in the first embodiment of the present invention.

FIG. 3 is an enlarged view of only a shaft portion in the second embodiment of the present invention.

FIG. 4 is an enlarged view of only a shaft portion according to a third embodiment of the present invention.

FIG. 5 is a main configuration diagram of a conventional stepping motor.

[Explanation of symbols]

 1 Metal Lead Screw Shaft 1a Resin Lead Screw Shaft 1b Metal Rotor Shaft 11 Guide Pin 12 Driven System

Claims (3)

[Claims] 1. A stepping motor in which a lead screw made of resin is provided with a hole in a longitudinal direction thereof, and a metal shaft press-fitted into the hole is used as a motor shaft. 2. A stepping motor in which a cylindrical lead-hole made of resin is provided in a longitudinal direction and a metal shaft serving as a core is press-fitted into the lead-hole to form a motor shaft. 3. The lead screw portion is made of resin,
A stepping motor that has a resin-molded lead screw shaft so that the sliding part of the impregnated bearing contacts the metal shaft.