JPS6343564A - Linear stepping motor - Google Patents

Abstract

PURPOSE:To improve positioning accuracy by performing thermocompression welding with a pressure plate having a projection which is slightly smaller than the width of the chasing tooth of a comblike sheet. CONSTITUTION:A linear stepping motor is composed of a yoke, a permanent magnet, an excitation coil, a comblike sheet 4, comb teeth 5, a base 6, and the like. By putting the base 6 together with the comblike sheet 4, diffused junction and integral formation are performed. The diffused junction is performed by arranging an upper pressure plate 7 and a lower pressure plate 7' at upper and lower sections, and by using the thermal pressure welding jig with circular small projections 8 formed on the rear side surface of said upper pressure plate 7. Then, jointed sections 9 and 9' which are perfectly jointed by the small projections 8 are obtained in a state of the diffused junction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a linear stepping motor, and particularly to a small linear stepping motor with improved processing accuracy.

Conventional technology] Conventionally, in this type of small linear stepping motor, the teeth at the tip of the yoke containing the excitation coil were formed by machining with a grindstone, and the comb-like teeth opposite to the teeth at the tip of the yoke were formed by machining with a grindstone. The base was formed by half-etching, and according to these methods, the processing accuracy was ±10 μm and ±20 μm, respectively. However, as devices become more compact, the positioning accuracy of small linear stepping motors is required to be even higher, and conventional methods are no longer able to satisfy this requirement.

Therefore, the teeth at the tip of the yoke having the excitation coil are subjected to wire electrical discharge machining to improve the pitch accuracy of the teeth to be less than ±5 μm and the shape accuracy to be less than ±1 μm. In addition, by separating the base that faces the teeth of this yoke into a thin plate with comb teeth and the base, and forming the thin plate with comb teeth by full etching, the pitch of the comb teeth is within ±3 μm, and the shape accuracy is ±0. It can be formed to a thickness of .5 μm or less. Further, by diffusion bonding the thin plate having the comb teeth to the base, it is possible to ensure the bonding.

[Problem that the invention seeks to solve]

In the conventional linear stepping motor described above, the pitch accuracy and shape accuracy can be greatly improved by separating the thin plate having the comb teeth from the base and forming the comb teeth by full etching. However, when diffusion bonding is performed using a thin plate having high-precision comb teeth as a base, there is a drawback that elongation of several tens of μm occurs in the pitch direction. Although it was possible to improve the accuracy of each by separating the thin plate having the comb teeth and the base, there is a drawback that the accuracy deteriorates at the stage of diffusion bonding.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to diffuse bond the base and the comb-shaped thin plate while maintaining high precision.
An object of the present invention is to provide a small linear stepping motor with good positioning accuracy.

[Means for solving problems]

The linear stepping motor of the present invention includes a comb-tooth thin plate facing the teeth of a yoke with a minute gap, and a base stacked on the comb-tooth thin plate, and is provided along the comb teeth of the comb-tooth thin plate. The comb tooth-like thin plate and the base are installed between an upper pressing plate and a flat lower pressing plate having small protrusions slightly smaller than the width of the comb teeth, and the small protrusions are The comb tooth-like thin plate and the base are integrated by positioning the base so as to be on the teeth, and applying pressure and heating using the upper press plate and the lower press plate to perform diffusion bonding.

[Effect]

In the diffusion bonding of the comb-like thin plate and the base, the present invention does not press the entire surface to suppress the elongation of the comb-like thin plate, but performs partial pressure-welding with dimensions smaller than the width of the comb teeth of the comb-like thin plate. It is something. For this reason, the comb teeth of the comb tooth-shaped thin plate that are not pressed tend to widen slightly (several μm), but this has no effect on the overall length and dimension in the direction between pitches.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Figures 1 (a), (b), and (c) are exploded perspective views of one embodiment of the present invention, Figure 2 is an enlarged perspective view of essential parts of this embodiment, and Figures 3 (a) and (b). 1 is an overall perspective view and an enlarged perspective view of a main part of a thermocompression bonding jig used for diffusion bonding in this embodiment.

This embodiment has a yoke 1, a permanent magnet 2, an excitation coil 3, a comb-shaped thin plate 4, comb teeth 5, a base 6, and a joining portion 9.9'. A plate 7, a lower pressing plate 7' and a small protrusion 8 are used.

The teeth at the tip of the yoke 1 are formed by wire electrical discharge machining, and a permanent magnet 2 is fixed to the center thereof. The excitation coil 3 is inserted into the toothed portion of the yoke 1. Comb-shaped thin plate 4
The comb teeth 5 are processed by full etching on a silicon steel plate having a thickness of several tens of μm. By processing this comb tooth-shaped thin plate 4 by full etching, the pitch accuracy of the comb teeth 5 can be increased to 5.
It can be formed with a shape accuracy of ±1 μm or less.

The base 6 is integrated by overlapping the comb-like thin plates 4 and diffusion bonding them. As shown in FIG. 3, there are an upper pressing plate 7 and a lower pressing plate 7' on the upper and lower sides, and a small round projection 8 is formed on the back side of the upper pressing plate 7. The small protrusions 8 are provided equal to the pitch interval of the comb teeth 5,
Although the diameter is smaller than the width of the comb teeth 5, it does not have to be round, and the pitch P in the longitudinal direction of the comb teeth 5 is not particularly limited, but if it is too large, problems such as floating may occur. .

When performing diffusion bonding with this embodiment having such a configuration, the comb tooth-like thin plate 4 and the base 6 are installed so that the comb teeth 5 and the small protrusions 8 are maintained on the same pitch, and the comb teeth are After positioning the shaped thin plate 4 and the base 6, they are sandwiched from above and below between an upper pressing plate 7 and a lower pressing plate 7' for thermocompression, a pressing force of 2-4) cg/mm2, a heating temperature of 400-700°C
The tooth-shaped thin plate 4 and the base 6 are joined under the joining conditions of a heating time of 1 to 2 hours.

Figure 2 shows the state of diffusion bonding according to this example.
A completely joined joint 9 and 9' is obtained by means of the small protrusion 8.

〔Effect of the invention〕

As explained above, in the present invention, the comb-like thin plate and the base can be easily diffusion-bonded by thermocompression bonding using a pressure plate having small protrusions that are slightly larger than the width of the comb-like thin plate. During bonding, the bonded portion on the comb teeth expands slightly (1 μm) in the width direction, but this has the effect of minimizing the effect on pitch errors. In addition, although the non-pressed portions between the bonded portions are not bonded, they do not bulge and are in perfect contact with each other, so that the non-bonded state has no effect on the magnetic circuit at all.

As a result of the measurement, as mentioned above, the spread of the joint is 1
The error per pitch is less than .mu.m and at the same time the error per pitch is less than submicron, which is extremely high precision and causes no problems in use. As a result, the positioning accuracy according to the present invention is
We were able to secure μm.

[Brief explanation of drawings]

Figures 1 (a), (b), and (c) are exploded perspective views of one embodiment of the present invention, Figure 2 is an enlarged perspective view of essential parts of this embodiment, and Figures 3 (a) and (b). 1 is an overall perspective view and an enlarged perspective view of a main part of a thermocompression bonding jig used for diffusion bonding in this embodiment. DESCRIPTION OF SYMBOLS 1...Yoke, 2...Permanent magnet, 3...Exciting coil, 4...Comb tooth-like thin plate, 5...Comb tooth, 6...
Base, 7... Upper pressing plate, 7'... Lower pressing plate,
8...Small protrusion, ~, ---'th l concave, 5<L multi$2 concave

Claims (1)

[Claims] In a linear stepping motor comprising a comb-shaped thin plate facing the teeth of a yoke with a minute gap and a base stacked on the comb-shaped thin plate, the comb-shaped thin plate is provided along the comb teeth of the comb-shaped thin plate, and the comb teeth are provided along the comb teeth of the comb-shaped thin plate. The comb tooth-shaped thin plate and the base are installed between an upper pressing plate having small protrusions slightly smaller than the width dimension of the comb teeth and a flat lower pressing plate, and the small protrusions are placed on the comb teeth. The linear stepping motor is characterized in that the comb-shaped thin plate and the base are integrated by positioning the plate in the same manner as shown in FIG.