JPH0318424B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a linear stepping motor.

(Prior art) In a linear stepping motor in which a mover is moved relative to a stator,
It is necessary to accurately perform relative linear motion between the mover and the stator. Therefore, in conventional linear stepping motors, it has been considered to move the mover with high accuracy relative to the stator by using a guide means with low frictional resistance, and various guide means for this purpose have been considered.

Conventionally, a commonly used guide means is such that the inner ring of a ball bearing is fitted onto a shaft protruding from the side of the mover, and the flanged outer ring of the ball bearing is used as a wheel to freely roll on a rail portion formed as a part of the stator. The mover is mounted on the stator so that it can move linearly along the stator rail.

Another conventionally used guide means is one in which a guide groove having a V-shaped cross section is provided at opposing positions of the mover and the stator, and a steel ball is interposed between the opposing V-shaped grooves. The mover is moved linearly in the direction of the V-shaped guide groove. There is also one in which the guide groove is formed in a loop shape, and a large number of steel balls are interposed in the guide groove to circulate the steel balls.

In any of the guide means, the rail portion and the contact portion with the steel ball are made of a highly hard material such as steel or ceramics in consideration of wear resistance. On the other hand, the mover body is required to be rigid and non-magnetic, so a thick plate material such as aluminum or brass is used. In addition, in short stroke motors that have a structure with coils or magnets on the stator side, the stator body is required to be non-magnetic like the mover, and the shape is often complicated, so the stator body is made of aluminum. Die casting is often used.

(Problems to be Solved by the Invention) If ball bearings are used as guide means, the cost of the ball bearings is high, and at least four of them are required, which increases the cost of the motor. In addition, when a ball bearing with a flange is rolled on a rail, the flange of the bearing comes into contact with the side of the rail and rattles. It is unsuitable as a driving source. Furthermore, errors are likely to occur due to the accumulation of vibrations in the wheels made of ball bearings, accuracy errors in the spindles of the ball bearings, and the like.

According to the method using steel balls and guide grooves as the guide means, the guide groove part is formed of a high hardness material separately from the mover and stator bodies, and is attached to the mover and stator bodies. Also, installation errors of the guide groove portion to the stator body are likely to occur. Moreover, when the guide portion is formed of ceramics, the means for fixing the mover and the stator must be adhesive, which is inefficient in mass production. Further, according to the circulating steel ball type in which the guide groove is formed into a loop, the shape of the guide groove becomes complicated and the processing cost increases.

In any case, in a linear stepping motor, a strong suction force acts between the stator and mover, so the stator and mover must be able to withstand the suction force, not wear out, and have high rigidity. Due to problems with motor characteristics, it is necessary to maintain a constant distance between the stator and mover, but with conventional linear stepping motors,
There are many cumulative causes of errors in related parts, and it is not easy to maintain the air gap between the mover and the stator within a predetermined range, and the characteristics of the motor tend to become unstable.

It is an object of the present invention to reduce the cumulative factors of parts errors related to the accuracy of the air gap between the mover and the stator, so that a predetermined air gap can be easily secured, and to ensure that the air gap between the mover and the stator is strong enough. It can easily withstand strong suction forces, does not wear out, and has great rigidity.
Furthermore, it is an object of the present invention to provide a linear stepping motor that is easy to assemble and inexpensive by simplifying the structure of the guide means.

(Means for Solving the Problems) The present invention is a linear stepping motor in which a mover is moved relative to a stator via a guide body, and the mover and the stator each have a magnetic circuit forming member as a part thereof. The guide bodies are placed on both sides of the magnetic circuit forming member in a direction intersecting the direction of relative movement of the mover and stator, and the mover and stator are also held so that the magnetic circuits of both of the members are exposed. The forming members are arranged to face each other at a predetermined interval with the guide body interposed therebetween, and at least one of the mover or the stator has a portion in contact with the guide body that is a ceramic receiving portion. , and almost the entire portion other than the magnetic circuit portion is a ceramic body integrally molded with the ceramic receiving portion.

(Function) The mover is supported so as to be movable in a linear direction on the stator by the guide body interposed in the ceramic receiving part. A predetermined magnetic circuit is formed between the mover and the stator, and the mover is step-driven by energizing the drive coil. A magnetic attraction force acts between the stator and the mover, but the guide body receives the magnetic attraction force by contacting the ceramic receiving part of at least one of the mover or the stator and the other receiving part. Both magnetic circuit forming members of the mover face each other at a predetermined interval.

(Example) In FIGS. 1 to 5, reference numeral 1 indicates a mover and 5 indicates a stator frame. mover 1
is made into a plate shape by molding ceramics, and has high hardness and non-magnetic properties. As shown in detail in FIG. 6, the mover 1 also has a V-shaped guide groove 21 on one side edge of the lower surface and a flat guide groove 21 on the other side edge of the lower surface by integral molding of ceramics. The portion 22 is integrally formed. The stator frame 5 is the mover 1
The guide groove 2 of the mover 1 is made by integral molding of ceramics, as shown in detail in FIG.
V-shaped guide grooves 23 and 24 are integrally formed at positions facing the guide portion 1 and the guide portion 22. Steel balls 3 are interposed between the guide groove 21 of the mover 1 and the guide groove 23 of the stator frame 5, and between the guide portion 22 of the mover 1 and the guide groove 24 of the stator frame 5, respectively. The steel ball 3 rolls within the guide grooves 23 and 24, and the mover 1 moves into the guide groove 2.
1. Guide part 22 and guide grooves 23 and 24 form a guide body that guides movement linearly in the direction, and guide groove 21, guide part 22 and guide grooves 23 and 24 form a receiving part in contact with the steel ball 3. I am doing it. These guide grooves 21, guide portions 22, and guide grooves 23, 24 are integrally formed with the mover 1 or the stator frame 5, so that errors in mounting them to the mover 1 or the stator frame 5 do not pose a problem. However, since the mover 1 and the stator frame 5 are made by integral molding of ceramics, the guide groove 21 and the guide part 2 may be
2. The surfaces of the guide grooves 23 and 24 shall be polished by secondary processing to achieve surface accuracy. Since the guide portion 22, which is a receiving portion for one of the steel balls 3 of the mover 1, is formed flat, the parallelism of the two surfaces forming the V-groove does not matter as in the case of a V-groove.

The guide grooves 23 and 24 of the stator frame 5 have a vertical circulation structure for the steel balls 3 by connecting the steel balls 3 to the return path at both ends thereof. That is, as shown by the guide groove 23 on the left side in FIGS. 2 and 4, a protruding edge 5a having the guide groove 23 is formed on the side surface of the stator frame 5, and this protruding edge 5a and In order to form a tunnel-like steel ball return path 25 into which the steel balls 3 can enter,
A ball holder 6 is fixed to the side surface of the stator frame 5. Guide groove 2 configured in this way
3 and the return path 25, a large number of steel balls 3 are arranged in a dense manner, and the steel balls 3 that have rolled in the guide groove 23 to guide the movement of the mover 1 enter the return path 25 and return to the return path 25. After returning to the ring via the return route 25, it is used again to guide the mover 1. Therefore, only the guide groove 23 that guides the movement of the mover 1 needs to be polished in the secondary processing of the stator frame 5. It is sufficient that the return path 25 has the function of smoothly moving the steel ball 3.
Therefore, the ball holder 6 is made of synthetic resin, and is fitted into the side of the stator frame 5 in a snap fit manner using the elastic force of the synthetic resin, as shown in the ball holder 6 on the right side in FIG. Structure is fine. In order to integrally mold the protruding edge portion 5a as described above on the stator frame 5, the mold is divided into upper and lower halves. Right guide groove 2
4 is also a return path 25 that is continuous with the guide groove 23 on the left side.
It is assumed that the route is continuous with the same return route as .

In FIGS. 1 to 5, reference numeral 10 denotes a stator core, which has a structure in which a plurality of plates made of magnetic material are laminated and caulked, and the periphery of the lower end is fixed to the core holder 9 by spot welding. has been done. The core holder 9 is made of a non-magnetic material and is fixed to the stator frame 5 with an appropriate number of screws 17. The stator core 10 constitutes the cores of two coils, and in the illustrated embodiment, the central portions of the two cores are integrally connected in the width direction by a narrow rib 27 in the planar shape.
Therefore, the relative pitch accuracy of the teeth formed on the two core parts can be easily achieved, and furthermore, since the ribs 27 are thin as described above, they are easily magnetically saturated, and no extra magnetic path is formed. It's becoming like that.

A pair of left and right mover cores 13, 13 are arranged in the longitudinal direction on the lower surface of the mover 1, and a nut 16 is screwed into a non-magnetic stud 28 welded to the upper surface of these mover cores 13, 13. 13, 13 are integrally fixed to the mover 1. The mover cores 13, 13 are formed with teeth at regular intervals in the width direction by performing so-called non-rolling or gear cutting in which a roller having teeth around the periphery is pressed against a square lumber material. The teeth of the left and right mover cores 13, 13 are shifted in phase by half a pitch, but this phase shift can be achieved by attaching mover cores 13, 13 of the same shape in opposite directions. A rod-shaped magnet 12 is placed between the pair of mover cores 13, 13 so as to be sandwiched between the mover cores 13, 13. The magnet 12 is held by the attraction force between it and the mover cores 13 and also by the adhesive tape interposed between it and the mover 1.

Two coil sets each consisting of a winding 30 and its bobbin 8 are fitted into the stator core 10. Each bobbin 8, 8 is fixed to the core holder 9 by inserting its pin-shaped protrusion 8a, 8a into a hole in the core holder 9 and heat caulking. Two terminals 7 are fixed to each bobbin 8, 8 by press-fitting or insert molding, and the beginning and end of winding 30 are connected to each terminal 7 by soldering, etc. One end of a lead wire 4 for external connection is connected to 7. The wiring section including the terminal 7 is covered with a part of the ball holder 6 and insulated from the outside.

Stator core 10 and mover core 13, 13
constitutes a magnetic circuit forming member, and is held on the stator side and the mover side so that a part is exposed on the opposing surface side. Guide groove 21, guide part 22, guide grooves 23, 24 forming the receiving part
Steel balls 3 forming guide bodies are arranged on both sides of the magnetic circuit forming member in a direction intersecting the direction of relative movement between the mover 1 and the stator.

A mounting plate 15 is fixed onto the mover 1 with screws 14. The mounting plate 15 prevents the magnetic flux from the motor side from leaking to the outside, and also allows a user of the motor to attach various devices, such as a magnetic head support in a disk device.

By arranging the mover 1 and the stator to face each other with the steel ball 3 intervening as a guide,
A predetermined air gap is formed between the stator core 10 and the mover cores 13,13. This predetermined air gap is created by simultaneously polishing the upper surface of the stator core 10 when the surfaces of the guide grooves 23 and 24 of the stator frame 5 are polished by secondary processing, and also by polishing the surfaces of the guide grooves 21 and guide portions 22 of the mover 1. When polishing the mover core 13,1 in secondary processing.
This can be easily secured by simultaneously polishing the lower surfaces of 3.

The motor thus formed is covered with a dustproof cover 2. The dustproof cover 2 is fixed to the stator frame 5 with screws 31 so as to cover the top of the motor, and has a dustproof function. 2a is formed, and by bringing the end surface of the mounting plate 15 into contact with the edge of this window hole 2a, the mover 1 is prevented from overrunning and separating from the stator frame 5.

The entire portion including the stator frame 5, stator core 10, winding 30, etc. constitutes the stator, but other stator portions other than the magnetic circuit portion including the stator core 10, the winding 30, etc., that is, the stator frame 5 The entire body, including the guide grooves 23 and 24 serving as receiving portions for the steel balls 3 which are the guide bodies of the mover 1, is integrally molded from ceramics. Similarly, it has a mover 1, a magnet 12, mover cores 13, 13, etc., and the entire portion that moves relative to the stator constitutes a mover in a broad sense. The other parts of the mover except for the magnetic circuit part, that is, the entire mover 1, including the guide groove 21 and the guide part 22 serving as the receiving part for the steel ball 3, are integrally molded of ceramics. There is.

In the above embodiment, the magnetic circuit is a so-called hybrid stepping motor formed by the central magnet 12 on the mover 1 side, the mover cores 13, 13 on both sides of the magnet 12, and the stator core 10. The mover 1 is caused to perform a step operation by supplying power to the wires 30 and 30 to cause attraction and repulsion between the stator core 10 and the mover cores 13 and 13. As the mover 1 moves, the steel balls 3 forming the vertical circulation ball bearing move into the guide groove 21 and guide portion 22 of the mover 1.
and guide grooves 23, 24 of stator frame 5
It rolls inside and guides the linear movement of mover 1.
Since the steel balls 3 constitute a rolling bearing, resistance to movement of the mover 1 is small. Steel balls 3 rolled to the ends of the guide grooves 23 and 24 of the stator frame 5
enters the return path 25 that is continuous with the guide grooves 23 and 24, and is pushed by the steel ball 3 coming later and repeats rolling.

In the normal operating range, the mover 1 does not hit the inner surface of the window hole 2a of the dust-proof cover 2, which is a mechanical stopper, but if it exceeds the operating range, the end face of the mounting plate 15 will not hit the window hole 2a of the dust-proof cover 2. It is stopped when it hits the inner surface of the Furthermore, the mover 1 is held on the stator frame 5 by the suction force of the magnet 12, and it is not possible to separate the mover 1 from the stator frame 5 unless you consciously pull it away. A dustproof cover 2 mechanically prevents the dustproof cover from falling off.

Since the stator core 10 and the core holder 9 have a structure that allows them to be fixed at any relative position,
Utilizing this, the relative positions of both parts can be adjusted and fixed according to the dimensions of other parts. For example, when fixing the core holder 9 to the stator frame 5, the relative position can be determined by setting the dimensions determined from the dimensions of other parts. It is also possible to weld the stator core 10 and the core holder 9 with a spacer having a thickness of .

Further, in the above embodiment, since the external lead wire 4 is directly connected to the terminal 7 fixed to the bobbin 8, a printed circuit board for wiring is not required. In fixing the mover cores 13, 13 to the mover 1, a non-magnetic stud 28 is fixed to the mover cores 13, 13 and this is fixed to the mover 1. , 13 do not adversely affect the magnetic path of the mover 1 and other parts, and there is no leakage of magnetic flux to the outside.

Since the stator frame 5 is made of ceramics with good insulation, the stator frame 5 may directly hold current-carrying parts such as terminals. This will eliminate the problem of heat during soldering.

The invention may be modified as shown in FIGS. 7-10.

In the example shown in FIG. 7, a vertical circulating ball bearing 33 is formed by rotating the stator 34 and the mover 35 in reverse order, and the steel balls 36 are circulated on the mover 35 side. According to this example:
The moving distance of the mover 35 can be increased.

In the example shown in Fig. 8, the bearing type between the stator and mover is a roller type using rollers 38.
The example shown in FIG. 9 uses a horizontal circulation type bearing using steel balls 39, and the example shown in FIG. The wheel 40 is rotatably supported, and the wheel 40 is rotatably mounted on a stator.

In any of the examples shown in FIGS. 7 to 10, at least one of the mover and the stator is made of ceramics in almost its entirety except for the magnetic circuit part, and includes steel balls 36 and rollers 3 as guide bodies.
8. The receiving portion that contacts the steel ball 39 and the wheel 40 is molded of ceramics integrally with the ceramic mover or stator main body portion.

Note that a metal plate may be inserted into a ceramic mover or stator, and the receiving portion of the guide and the holding portion of the current-carrying component may be formed of ceramic.

When attaching the linear stepping motor of the present invention to various types of equipment, the stator may be made variable in position relative to the equipment.

(Effects of the Invention) According to the present invention, since the mover or stator main body and the receiving part of the guide body are integrally molded with ceramics, there is no need to fix the receiving part of the guide body to the mover or stator, Errors due to this do not occur, and processes such as adhesion for fixing are not required, making it possible to improve productivity and product quality. In addition, in a stepping motor, a strong suction force acts between the stator and mover, so the stator and mover must be able to withstand the suction force, not wear out, and have high rigidity. In view of the above problem, it is possible to ensure a constant distance between the stator and the mover, and according to the present invention, this requirement can be satisfied by integral molding of ceramics.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view taken along the line - in Figure 1, Figure 3 is a vertical cross-sectional view of the central part of Figure 1, Figure 4 is a partially cutaway left side view of Figure 1, and Figure 5 is a cross-sectional view of the above implementation. FIG. 6 is a cross-sectional view showing an enlarged view of the receiving portion of the guide body in the above embodiment, FIG. 7 is a partially sectional side view showing another embodiment of the present invention, and FIG. 8 is a bottom view of the example. FIG. 9 is a perspective view showing still another embodiment of the invention. FIG. 10 is a perspective view showing still another embodiment of the invention. 1... Mover, 3... Steel ball as a guide, 5...
Stator frame, 21, 23, 24... Guide groove as a receiving part, 22... Guide part as a receiving part,
34... Stator, 35... Mover, 37... Shaft as receiving part, 38... Roller as guide body, 40
...wheels as guides.

Claims (1)

[Claims] 1. In a linear stepping motor in which a mover is moved relative to a stator via a guide body, the mover and the stator each hold a magnetic circuit forming member so that a part of the member is exposed. The guide bodies are arranged on both sides of the magnetic circuit forming member in a direction intersecting the relative movement direction of the mover and the stator, and the mover and the stator are further arranged such that both magnetic circuit forming members are separated by a predetermined interval. At least one of the mover and the stator has a ceramic receiving portion in contact with the guide, excluding a magnetic circuit forming portion. A linear stepping motor characterized in that almost the entire other portion is a ceramic body integrally molded with the ceramic receiving portion.