JPS58136261A - Rotor for step motor - Google Patents

Abstract

PURPOSE:To improve the performance of a step motor by forming the shape of projections formed at a constant pitch on the outer periphery of a body in an involute tooth shape and forming at the end a parallel tooth crest having a constant width larger than the polishing margin of outer diameter. CONSTITUTION:This rotor is formed at the shape of projections 11 formed at a constant pitch on the outer periphery of a body 10 supported by a rotational shaft in an involute tooth shape, and formed at the end of the tooth with a parallel tooth crest 12 having a constant width W larger than the polishing margin of outer diameter at the radial thickness (h). In this manner, the accuracy management can be facilitated by measuring the pitch error between the projections 11 by utilizing a tooth measuring implement, and the pitch error can be suppressed to a small value. The irregular thickness at the end of the tooth produced after polishing the outer diameter caused by the inner and outer diameter fluctuations of the body 10 can be prevented. Accordingly, the pitch and end thickness of the projections 11 can be accurately finished, thereby improving the performance of the step motor.

Description

[Detailed Description of the Invention] This invention is a rotor used in a step motor! Regarding S.

The stave motor, which rotates by a certain fixed angle each time a human power pulse is applied, has protrusions 3.4 at fixed pitches on the inner periphery of the stator 1 and the outer periphery of the rotor 2, respectively, as shown in Fig. 1. The performance is greatly influenced by the pitch accuracy, thickness accuracy, and shape of these protrusions. Therefore,
In this type of motor, not only the stator but also the rotor are required to be manufactured with high precision in order to ensure output torque characteristics that provide stable rotation.

In the conventional rotor, it is difficult to finish the shape of the protrusion 4 with high precision in both the pitch and the thickness of the tip, as shown in Fig. It1.

In other words, the rotor that adopts the impoliced tooth profile shown in Figure 2 allows the use of a gear measuring device, making it easy to measure pitch errors, and this shape is suitable for machining, so pitch accuracy can be maintained even during machining. Easy to release. However, in this type of rotor, the clearance between the stator and the stator is maintained at one foot.
However, after forming the protrusions, it is necessary to polish the outer periphery to finish the outer diameter with high precision.On the other hand, it is impossible to avoid so-called "runout" in which the central axes of the inner and outer diameters are misaligned. After diameter polishing, an error occurs in the thickness of the tooth tip of each protrusion 4 due to the influence of this "runout".

On the other hand, in the rotor employing the rectangular protrusions shown in FIG. 4, the width of the protrusions is constant, so the error in the tip thickness after polishing the outer diameter can be suppressed to a small range. However, with this shape, it is difficult to measure the pitch error and it is difficult to process with high precision, so that pitch deviation occurs between the respective protrusions, which adversely affects the performance of the motor.

The present invention has been made in view of this point, and its purpose is to provide a high-precision rotor that further improves the performance of a step motor.

Hereinafter, this invention will be explained based on the attached FIG. 3. As shown in the drawings, the rotor of this invention has protrusions 11 provided at a constant pitch on the outer periphery of a main body 10 supported by a rotating shaft, with an involute tooth shape. , and a tooth tip parallel portion 12 having a constant width W and a radial thickness h larger than the outer diameter polishing allowance at the tip of the tooth.
It is formed.

As mentioned above, the reason why the protrusions 11 have an involute tooth profile is to facilitate accuracy control and keep pitch errors small by measuring the pitch error between each protrusion using a gear measuring device.

In addition, the parallel tooth tip section is provided at the tip of the protrusion in order to prevent variations in the thickness of the tooth tip that occur after polishing the outer diameter due to runout of the inner and outer diameters of the main body. If the outer diameter is polished inside, the center W of the tip will not change.

This rotor can be manufactured by a process using a hobstone or the like, a pressed product lamination method in which a large number of thin plates press-formed into the shape shown in FIG. 3 are laminated, or a sintering method.

However, when cutting gears by machine reduction machining, even though the involute tooth profile is relatively easy to machine, it is difficult to machine the parallel tooth tips at the same time, which increases the number of machining steps and is disadvantageous in terms of cost. In addition, although the pressed product lamination method is advantageous in terms of cost compared to the former, errors are likely to occur due to the overlapping of plates, so a process to correct the errors is required, and it is not expected that the errors will be completely corrected. Can not.

In this respect, the sintering method is most suitable for manufacturing the rotor of the present invention because it does not require a process for maintaining accuracy through combinations and is easy to manufacture.

Note that the illustrated parallel portions 12 of the tooth tips of the rotor are exaggerated in order to make it easier to understand the content of the invention. In other words, the teeth (the size of the protrusions) formed on this type of rotor are
．． For example, a rotor with teeth of 0.8 module has an outer diameter polishing allowance of 0.05 to 0.15.
(0.1 to 0.3 m in diameter), it is sufficient that the dimension of the parallel portion of the tooth tip to be actually formed is slightly larger than this value.

As explained above, this invention is characterized in that the protrusion has an involute tooth profile, and a parallel tooth tip portion with a constant width larger than the outer diameter polishing allowance is formed at the tip of the protrusion. Both the pitch and the tip thickness can be finished with high precision, making it possible to further improve the performance of the step motor.

Furthermore, the rotor manufactured by the sintering method can be provided at a low cost since it can reduce the cost, making a large contribution to the economy.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a conventional step motor, FIG. 2 is a front view showing one of the conventional rotors, and FIG. 3 is a front view showing a part of the rotor of the present invention. 10 is a main body, 11 is a protrusion, and 12 is a tooth tip parallel portion.

Claims (1)

[Scope of Claims] (11) For a step motor characterized by: (11) protrusions provided at a constant pitch on the outer periphery of the main body have an involute tooth shape, and a constant parallel tooth tip portion is formed at the tip of the tooth; Rotor. (21) The rotor for a step motor according to claim 1, wherein the rotor is manufactured by a sintering method.