JPH0524743B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing a linear pulse motor used for linearly moving the head of a disk drive device, and particularly to a method of manufacturing a small linear pulse motor. It is related to.

[Conventional technology]

Conventionally, the yoke into which the excitation coil of a small linear pulse motor is inserted is shaped so that the width of the teeth at the tip is
Because it is about 0.4 mm, it was done by slicing with a grindstone, or by machining with a lathe, press, etc. Furthermore, the comb-shaped slider facing the teeth at the tip of the yoke was similarly formed by slicing with a grindstone or machining.

[Problems to be Solved by the Invention] When the yoke is manufactured by machining as described above, the teeth at the tip of the yoke are processed with a grindstone and machined, resulting in a poor processing accuracy of ±10 μm to ±μm. Furthermore, there were problems such as burrs and warping occurring during processing, which required post-work. Another drawback was that it was difficult to maintain highly accurate shapes when assembling some parts of the yoke. However, as devices become smaller, small linear pulse motors also become smaller and require higher positioning accuracy, and conventional manufacturing methods can only provide linear pulse motors that are satisfactory in terms of minute feed, high-precision positioning, and miniaturization. I couldn't get the motor to work.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a linear pulse motor that eliminates the above-mentioned drawbacks, allows a yoke to be processed and assembled with high precision, and provides a high-torque linear pulse motor with good positioning accuracy. .

[Means for solving problems]

A method for manufacturing a linear pulse motor according to the present invention includes a yoke in which a plurality of coil portions each having an excitation coil and first teeth are fitted into a flat plate portion, and a second tooth opposite to the first teeth. A method for manufacturing a linear pulse motor including a mover made of a magnetic material having a metal injection molding step of forming the plurality of coil portions in an integral state in which the plurality of coil portions are connected to each other at a connecting portion; The method includes a fitting step of fitting a plurality of coil portions to the flat plate portion, and a removing step of removing the connecting portion after the fitting step.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2 are a longitudinal sectional view and an exploded perspective view, respectively, of a small linear pulse motor manufactured according to an embodiment of the present invention. The yoke 1 is composed of a coil portion 5 of a flat plate portion 12. Further, the coil portion 5 is a flat plate portion 6 at the tip, which is a rectangular flat plate provided with teeth 11 of a constant pitch.
A cylindrical shaft 1 whose central part is attached to an excitation coil 3
3, and the rear end is formed as a cylindrical fitting part 7.

A permanent magnet 2 is provided at the center of the flat plate portion 12. The excitation coil 3 is attached to the shaft 13 of the yoke 1 by forming a conductive wire into a spiral shape and providing a lead wire 31. The mover 4 is made of a magnetic material, is provided facing the flat plate portion 6 at the tip of the yoke 1, and is guided so as to be movable in the longitudinal direction (hereinafter referred to as the X direction) by a guide means not shown. .

The part of the mover 4 facing the flat end plate part 6 of the yoke 1 is slightly wider than the entire width of the four arranged flat end parts 6, and is arranged at the same pitch as the teeth 11 and in the same direction (the short length of the mover 4). Teeth 14 are provided in the side direction (hereinafter referred to as the Y direction). Teeth 11 of two of the four tip flat plate parts 6 aligned in the Y direction
are at the same position in the X direction, and the X
For those arranged in the same direction, the positions of the respective teeth 11 in the X direction are shifted by half a bit from each other. The permanent magnet 2 constitutes a magnetic circuit together with the yoke 1, and the movable element 4 is moved in the X direction by appropriately switching the excitation of the coil 3.

Next, a method of manufacturing the above-mentioned small linear pulse motor will be explained.

The four coil parts 5 of the yoke 1 are simultaneously molded by metal injection molding. At this time, the four coil parts 5 are connected to each other by a liner (not shown) serving as a connecting part and are integrated.

Further, the flat plate part 12 is manufactured by molding the part excluding the permanent magnet 2 by metal injection molding so as to have a hole 15 and a groove in the center, and incorporating the permanent magnet 2 into the groove in the center.

The excitation coil 3 is externally fitted onto the shaft 13 of the four coil parts 5 which are integrated by a runner, and the fitting part 7 is fitted into the hole 15 of the flat plate part 12. After this, the runners that interconnected the coil portions 5 are removed.

In order to improve dimensional accuracy, the portions corresponding to the teeth 11 of the mold for metal injection molding the coil portion 5 are etched. Similarly, the mover 4 is also molded with fine grooves and teeth by metal injection molding.

The yoke of a conventional small linear pulse motor is 4
Since the coil portion of the body was separately fitted into the hole in the flat plate portion, rotational deviation and inclination of the coil portion occurred during this fitting, resulting in deterioration of dimensional accuracy.
However, in this embodiment, the coil parts 5 are integrated with a liner and are fitted into the holes of the flat plate part 12 at the same time, so rotational deviation and inclination of the coil parts 5 are prevented, the shape accuracy is ±8 μm or less, and the teeth The pitch accuracy can be improved to less than ±1 μm.

In addition, in conventional small linear pulse motors, the coil part is manufactured by machining using a milling machine, etc., so it is difficult to mold it into a complicated shape, and the part where the excitation coil is attached and the tip where the teeth are provided are prismatic. Therefore, each coil part had to be separated by the space of the excitation coil, resulting in a large shape. However, in this example, the coil parts are metal injection molded, making it easy to mold complex shapes, and by making the part where the excitation coil is attached a slightly thinner cylinder unlike the tip where the teeth are provided, each coil part can be brought closer together. It is possible to manufacture compact linear pulse motors.

〔Effect of the invention〕

The present invention provides a linear pulse motor with high dimensional accuracy by fitting a plurality of coil parts, which are integrally formed by connecting each other at a connecting part by metal injection molding, into a flat plate part and then removing the connecting part. It has the effect of being manufacturable.

The small linear pulse motor manufactured using the manufacturing method of the present invention not only has a fine step pitch of about 63.5 μm, but also has a positioning accuracy of ±2 μm.
The output torque was approximately 200 gcm, which was sufficient to drive the recording/reproducing head of a floppy disk device.

Further, the present invention has advantages such as easy mass production in a short time by metal injection molding, and linear pulse motors can be manufactured at low cost.

[Brief explanation of drawings]

1 and 2 are a longitudinal sectional view and an exploded perspective view, respectively, of a linear pulse motor manufactured according to an embodiment of the present invention. 1... Yoke, 2... Permanent magnet, 3... Excitation coil, 4... Mover.

Claims (1)

[Claims] 1. A yoke in which an excitation coil is externally fitted and a plurality of coil parts having first teeth are fitted into a flat plate part, and a mover made of a magnetic material and having second teeth facing the first teeth. A method for manufacturing a linear pulse motor comprising: a metal injection molding step of forming the plurality of coil parts in an integral state by interconnecting them at a connecting part; and fitting the plurality of integral coil parts into the flat plate part. A method of manufacturing a linear pulse motor, the method comprising: a fitting step of mating; and a deletion step of removing the connecting portion after the fitting step.