JPH08308167A - Motor with lead screw - Google Patents

Abstract

PURPOSE: To prolong the service life of a lead screw even when the length of the lead screw in the axial direction is shortened by sufficiently securing safety by setting the deformation caused by an energizing force applied to the lead screw from a pre-loading mechanism and by ensuring high-speed responsiveness by reducing the detent torque. CONSTITUTION: A motor with lead screw is provided with a bottomed hole section 5c having an inside diameter section concentrically formed at the other end of a lead screw 5, energizing member 9 provided in the hole section 5c, pressing member 10 the bottom face of which is brought into contact with the member 9 and which has at least a spherical surface on its surface facing the bottom face, and bearing member 12 which journals the screw 5 by partially entering the hole section 5c or the part of the member 10 protruded from the other end of the screw 5 so as to journal both ends of the screw 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor with a lead screw, which can be shortened in the axial direction when used as a drive for tracking a recording or reproducing head with respect to a disk-shaped recording medium, and The present invention relates to a motor with a lead screw having excellent durability.

2. Description of the Related Art Conventionally, in a magnetic disk device or the like, a lead screw which is a feed screw is formed on an output shaft of a stepping motor, and a desired head is mounted on a carriage which engages with the lead screw. 2. Description of the Related Art A magnetic disk device is known in which a head is accessed to a desired track on a disk by driving a stepping motor in a predetermined manner based on a command signal. In such a device, it is essential that the amount of rotation of the stepping motor is accurately converted into the parallel movement of the carriage without error in the rotation-linear motion conversion by reducing the play in the axial direction of the lead screw to zero. Is.

Therefore, it has been conventionally practiced to provide a preload mechanism for preventing the lead screw from moving in the axial direction at least in a normal operation state where an excessive load is not applied. Specifically, one end of the motor rotation shaft is rotatably supported by making one end of the motor rotation shaft immovable, while the other end of the motor rotation shaft is supported by a substantially one-sided spring arm of a predetermined length. A configuration in which a leaf spring provided with a biasing force in the axial direction has been widely adopted.

Referring to FIG. 11, a lead screw motor having a preload mechanism using a leaf spring, which is widely used in the prior art, will be described with reference to FIG.
The lead screw 105 is rotatably supported by the bearing 12 of the base 101, while the end portion of the lead screw 105 has a pivot bearing 20.
The leaf spring 109 is axially supported by the lead screw 105, and the leaf spring 109 is deformed with respect to the right end portion of the lead screw 105 to eliminate axial play of the lead screw 105.
The leaf spring 109 is fixed to a lid member fixed to the end of the coil 8 which is a stator. The lead screw 105 has a coil 1 fixed to the base 101.
A permanent magnet 107 made of a predetermined magnetic material is rotatably provided in the coil 08, and a rotating magnetic field is generated in the coil 108 to rotate the lead screw 105 by a predetermined amount.

Since the urging mechanism for urging in the axial direction by the leaf spring constructed as described above can be constructed very easily,
Although many springs have been put into practical use, the spring plate flexes in the longitudinal direction of the lead screw in a single-supported state to obtain the desired biasing force, so the variation in the total length of the lead screw in the axial direction is due to the preload mechanism. As a result of affecting the power, there is a problem that the preload accuracy cannot be guaranteed sufficiently. Also, depending on the variation in the overall length of the lead screw in the axial direction, the spring arm contacts in a state of being inclined with respect to the shaft end of the lead screw. However, there is a problem that a rather harmful biasing force is generated in the preload mechanism due to a radial component force, which may cause uneven wear of the relevant portion. In particular, when the leaf spring is constructed in a small size, the spring arm length cannot be taken sufficiently,
As described above, it becomes more and more difficult to prevent the state in which the spring arm is tilted and comes into contact with the shaft end.

Therefore, as disclosed in Japanese Utility Model Laid-Open No. 6-21383, there is also proposed one having a complicated preload mechanism for applying a preload by a leaf spring to a pivot bearing. Further, in order to allow the rotation center of the lead screw 105 to rotate without so-called shaft wobbling, a structure in which both ends are pivotally supported by pivot bearings is disclosed in, for example, Shokai Sho 60-236.
7, JP-A-63-77471. Further, Japanese Patent Application Laid-Open No. 6-105525 discloses a structure in which a lead screw shaft end is axially supported by a bearing which is composed of a metal bearing and a leaf spring. Has the drawback of being long.

On the other hand, as disclosed in Japanese Unexamined Patent Publication No. 6-133490, there has been proposed one provided with a biasing member which is movable in parallel by having a plurality of spiral slits instead of a leaf spring. ing. According to this disclosure, since the end portion of the lead screw is provided with the pressing portion having the spiral slit for preloading by the biasing member capable of moving in parallel, at least the spring arm of the leaf spring is inclined. In this state, it is possible to prevent contact with the shaft end of the lead screw, so that radial component force is not generated and harmful biasing force is not generated.For example, it is possible to prevent uneven wear of the bearing. It will be possible,
In any case, there is a drawback that the lead screw becomes long in the axial direction, so that the lead screw cannot be made compact.

[0007]

Again referring to FIG. 11, in the case of a conventional motor with a lead screw provided with a preload mechanism using a leaf spring, it can be constructed to be relatively short in the axial direction. However, according to this configuration,
Since the leaf spring is supported on one side, the displacement amount is small and unstable, and when pressing the end portion of the lead screw, a radial component force is generated depending on the deformed state of the leaf spring. As a result, the shaft end is not accurately located at the center of the coil 8, which causes a load during rotation. Also,
The so-called detent torque of the rotating load is generated when the power is not supplied.

On the other hand, as shown in the figure, the inner diameter portion of the bearing 12 that directly axially supports the middle portion of the lead screw has a positional relationship of axially supporting the lead screw as shown in the figure, so that the inner diameter cannot be reduced. Since the sliding area increases, the load during rotation cannot be reduced, which not only further increases the detent torque, but also causes a reduction in high-speed response.

Further, for example, when the leaf spring 109 is deformed as described above and a deviation H is generated between the leaf spring 109 and the center of rotation of the lead screw 105, a radial load F is generated in the permanent magnet 7 as a rotor. It will be. That is, assuming that the distance from the left end of the lead screw 105 to the bearing 12 is L1 and the distance from the bearing 12 to the central portion of the permanent magnet 7 is L2, the radial load determined by (L1 + L2) F / L1 is generated, and thus the bearing 12 There was a problem that adversely affects the durability of the.

Therefore, the present invention has been made in view of the above problems, and even if the lead screw is configured to be as short as possible in the axial direction, the deformation amount of the biasing force of the preload mechanism with respect to the lead screw is set to be larger. By doing so, stability can be sufficiently ensured, detent torque can be reduced to ensure high-speed response, and unreasonable force can be prevented from acting on the bearing to extend the life of the lead. The purpose is to provide a motor with a screw.

[0011]

In order to solve the above-mentioned problems and to achieve the object, a motor with a lead screw according to the present invention has one end rotated in an axially immovable state in order to eliminate axial play. A motor with a lead screw in which the other end is rotatably supported by being urged in the axial direction, and a lead screw groove portion is formed on the output shaft to provide a lead screw. A bottomed hole portion having an inner diameter portion formed concentrically at the other end of the lead screw, and a biasing member provided in the bottomed hole portion,
After the biasing member is inserted into the bottomed hole portion, the bottom surface of the pressing member is in contact with the biasing member and at least a spherical surface is formed on the surface facing the bottom surface, and with respect to the spherical surface. And a bearing member for supporting the pressing member that partially abuts from the other end while supporting the contacting and holding in the biased state and partially intruding into the inner diameter portion. It is characterized in that both ends of the lead screw are pivotally supported.

Further, preferably, the bearing member is fixed to a lid body fixed to the other end of a cylindrical stator, one end of which is fixed in a mounting portion for inserting an intermediate portion of the lead screw. It is characterized by that.

Further, preferably, the bearing member is fixed so as to be substantially fitted to the inner peripheral surface of the stator.

Further, preferably, the motor with lead screw is provided with an engaging portion which engages with the feed screw groove portion in order to use the recording or reproducing head for tracking drive with respect to a predetermined disc-shaped recording medium. In addition, it is characterized by comprising a carriage which is arranged so as to be movable in parallel with the lead screw and which carries the recording or reproducing head.

[0015]

In the above configuration, the biasing member provided in the bottomed hole portion having the inner diameter portion that is concentrically drilled at the other end of the lead screw, and the biasing member that is inserted subsequent to this biasing member and is at least spherical surface. By holding the pressing member that has been formed in a biased state and partially supporting it by sunk into the inner diameter portion, or by supporting the pressing member that is partially protruded by the bearing member, both ends of the lead screw are supported. By supporting it, the stroke of the pressing material is made sufficient to ensure the stability of the preload mechanism and eliminate axial backlash.
It works to reduce the detent torque to ensure high-speed response and to prevent excessive force from acting on the bearing to extend the service life.

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a main part of a motor with lead screw of the first embodiment in a broken manner. Is.

In the figure, the motor with a lead screw is mounted on the carriage 20 with respect to a disc-shaped predetermined recording medium (not shown) by moving the carriage 20 shown by the broken line in the figure along the shaft body 21. The recording / reproducing head is used for tracking drive. Also, the rotation is not limited to this.
The present invention is applicable to various devices having a linear motion converting mechanism, particularly when the device is configured to be short in the axial direction.

In order to construct such a rotation-linear motion converting mechanism, the carriage 20 is provided with an engaging portion for engaging with the feed screw groove portion 5a formed on the outer peripheral surface of the lead screw 5 without play. 20a is provided. Further, the shaft body 21 is arranged so as to be parallel to the lead screw 5 which is integrally formed with the motor output shaft, and a recording or reproducing head (not shown) is mounted on the carriage 20.

On the other hand, the base 1 has a left wall portion 1a as shown in the drawing.
And the right wall portion 1b are integrally formed into a substantially U shape, and the left wall portion 1a and the right wall portion 1b are substantially coaxial with each other to form the first through hole portion 1c and the insertion hole portion 1d, respectively. Has been drilled. A pivot bearing 2 is, for example, press-fitted and held in the first through hole portion 1c, and a ball 4 is rotatably incorporated in a ball guide portion 5b bored from the end of the lead screw 5. It is configured to be rotatable with almost no load in a state of point contact with.

Further, the insertion hole 1d has an inner diameter dimension with a margin because the lead screw 5 is inserted as shown in the drawing, while the inner diameter hole 6 of the mounting member 6 is provided.
By setting the inner diameter to be substantially the same as that of a, the coil 8 serves as a guide when the coil 8 is fixed to the right wall portion 1b of the base 1 via the fitting 6.

A permanent magnet 7 made of a predetermined magnetic material (including a resin magnet) is rotatably provided inside a coil 8 fixed to the base 1 via a mounting plate 6, and is shown in the lead screw 5. Thus, the carriage 20 is moved in an arbitrary direction by rotating the lead screw 5 by a predetermined amount by generating a rotating magnetic field in the coil 8.

Subsequently, a concentric circular bottomed hole 5c having a depth of more than about half the permanent magnet 7 and a predetermined inner diameter d1 is formed at the right end of the lead screw 5. A compression coil spring 9 having a predetermined wire diameter, a predetermined number of windings, and a predetermined outer dimension, the free length of which is set to, for example, 1.5 to 2 times as shown in the inside of the portion 5c, is incorporated. The rod-shaped member 10 is inserted following 9 and is held so that the bottom surface of the compression coil spring 9 comes into contact with the compression coil spring 9 and projects a predetermined amount from the right end portion 5d.

Further, the rod-shaped member 10 is capable of moving in the longitudinal direction in the inside of the bottomed hole portion 5c without rattling.
(Shown in FIG. 2), one end of which forms a spherical surface portion 10a as shown in the drawing, and the lid member 11 fixed to the bobbin side surface portion of the coil 8 by spot welding or the like. The contact surface 11a contacts the spherical surface portion 10a to prevent looseness in the axial direction.

Further, as shown in the drawing, an annular projection 11d having a shape to be fitted to the inner peripheral surface of the coil 8 is press-formed, for example, in the cover member 11, and the bearing 12 is fixed inside the annular projection 11d. The rod member 10 is pivotally supported. An oil diff 25 is interposed between the bearing 12 and the right end portion 5d, the bearing 12 is made of, for example, an oil-containing metal bearing, and the rod-shaped body 1 is formed in the bottomed hole portion 5c.
When the sliding grease of 0 is applied, they are separated from each other. Further, the bearing 12 may use a self-lubricating polyacetal resin, a crystalline polymer, or the like, and in this case, the oil diff 25 may be omitted.

By completing as described above, the total length L of the lead screw along the axial direction can be shortened, and the stroke of the compression coil spring 9 provided in the bottomed hole 5c having a sufficient depth dimension can be achieved. The stability of the preload mechanism can be sufficiently ensured, and both ends of the lead screw 5 can be pivotally supported.

Further, in FIG. 1, instead of the pivot bearing 2 described above, a bearing 102 which can be constructed at a lower cost may be provided at the end portion so that the spherical surface 5k receives a load in the thrust direction.

Next, FIG. 2 is a fragmentary sectional view showing a modified example of the motor with a lead screw having the configuration of FIG. In this figure, the same reference numerals are given to the already-explained configurations, and the description will be omitted to limit the description to the different parts. The bearing 12 is made of metal, and is similar to the lid member 11 made of a metal plate. It is spot welded. Further, the outer shape of the lid member 11 is similar to that of the coil 8 described above, and the respective outer shapes are aligned and then spot-welded to obtain the illustrated finished product. With such a configuration, the cost can be reduced.

FIG. 3 is a fragmentary cutaway view showing a modified example of the motor with lead screw having the configuration of FIG. 2, in which the same reference numerals are given to the already described configurations. The description will be omitted and the description will be limited to the different parts. Although the bearing 12 is made of metal, the caulking margins 12b are integrally formed at equal intervals of 120 degrees, and are preliminarily formed in the lid member 11 made of a metal plate. The caulking allowance 12b is provided in the caulking hole 11b being formed.
It is configured to be fixed by caulking after inserting. With this configuration, the configuration can be inexpensive.

FIG. 4 is a fragmentary cutaway view showing a modified example of the motor with lead screw.
The same reference numerals are given to the already described configurations, and the description will be omitted to limit the description to the different portions. When the lid member 11 is provided with the through hole portion 11c, the pivot bearing 120 is press-fitted therein. The spherical surface portion 10a of the rod-shaped member 10 abuts on the ball 121 that is held in a rolling manner inside the bearing 120 so as to be rotatable. According to this configuration, although the pivot bearing 120 is provided, the cost is increased, but there is an advantage that it can be configured to prevent axial play and rotate very lightly, and can rotate without a lubricant.

FIG. 5 is a fragmentary cutaway view showing a modified example of the motor with lead screw, which can be constructed at the lowest cost, and the cover member 11 is provided with a through hole 11c. The bearing 12 having self-lubricating property is press-fitted and fixed inside, and is guided in the circumferential direction in the shaft support hole 12a of the bearing 12 so that the spherical portion 10a of the rod-shaped body 10 abuts and is freely rotatable. By guiding, it is structured so as to prevent looseness in the axial direction and to rotate lightly without lubrication.

In each of the above-mentioned embodiments, the rod-shaped body 10 provided so as to partially project from the bottomed hole portion 5c formed from the right end portion of the lead screw 5 is rotatably supported by the bearing 12. In the second embodiment, a ball or a rod-shaped member, which is a member inserted subsequently to the compression coil spring 9 in the bottomed hole 5c, is directly pressed, and a projection portion that sneaks into the bottomed hole 5c is provided. It has a configuration in which the lead screw 5 is axially supported by a male bearing body.

FIG. 6 is a fragmentary cutaway view of a motor with lead screw according to the second embodiment. In this figure, the same reference numerals are given to the already described components, and the description thereof will be omitted. To be limited, the male bearing body 32 is made of metal and integrally formed with the caulking allowance 32k, and after the caulking allowance 32k is inserted into the caulking hole 11k formed in the lid member 11 made of a metal plate. It is fixed as shown by caulking. In this male bearing body 32, an abutment surface 32a and an outer peripheral surface 32b which are inserted into the bottomed hole 5c formed from the right end of the lead screw 5 following the compression coil spring 9 and directly press against the ball 30. Are integrally formed, and are brought into the illustrated shaft support state.

With the above construction, even if the lead screw 5 is constructed to be as short as possible in the axial direction like the construction of the first embodiment, the amount of deformation of the preload mechanism composed of the compression spring 9, the ball 30, and the male bearing body 32. By setting a larger value, stability can be sufficiently secured, and the diameter of the shaft support can be reduced to reduce the detent torque to ensure high-speed response. Can be prevented and the service life can be extended.

FIG. 7 is a fragmentary sectional view showing a modified example of the motor with lead screw having the structure of FIG. 6, and in this figure, the structures already described are given the same reference numerals for explanation. If omitted and described only in the different parts, the male bearing body 32 is made of a self-lubricating resin material, and the boss portion 32f is formed in the hole portion 11h formed in the lid member 11 made of a metal plate.
While the outer peripheral portion 32h is inserted into the inner peripheral surface 8 of the coil 8.
After being fitted to a, the lid member 11 is completed by spot welding S.

FIG. 8 is a fragmentary sectional view showing a modified example of the motor with lead screw having the structure of FIG. 7, in which the same reference numerals are given to the structures already described. If the description is omitted and the description is limited to different parts, the ball is formed into a bullet shape as illustrated and is supported by the male bearing body 32. The structure shown in FIG. 7 and FIG. 8 can be completed more easily and can be manufactured at a lower cost.

FIG. 9 shows a state in the process of assembling in the structure shown in FIG.
The free length of is when the bullet 30 is inserted as shown
It is configured so that a part thereof protrudes. As a result, the lid member 11 can be moved from the illustrated state in the direction of the arrow and completed by spot welding, so that, for example, when fully assembling the assembly process, automatic assembly by a robot device becomes possible.

From the above, according to each configuration of the above-mentioned embodiment,
It is possible to secure a sufficient deformation stroke for preloading the compression coil spring 9 which is the biasing member, and to make it sufficiently short in the axial direction (indicated by L in FIG. 1). Since a compression coil spring whose compression force is easily managed is used, it is particularly suitable for a motor with a lead screw having an outer diameter of 10 mm or less.

Finally, FIG. 10 is a schematic diagram common to each of the above-described embodiments, in which the distance from the left end of the lead screw 5 to the center of the permanent magnet 7 which is the rotor is L1 and the center of the permanent magnet 7 is It is the figure which showed the distance to the bearing 12 as L2. In the figure, the radial external force generated by the preload mechanism is L1P / (L1 + L2), and the radial load is reduced, so that the durability of the bearing 12 is improved.

The present invention is not limited to the above-mentioned embodiment, and various constructions are possible. For example, a pivot bearing may be replaced with a thrust bearing or a shaft end may be inserted into a simple hole portion. It is also possible to provide the pivot bearing on the motor installation side. Further, it goes without saying that the motor is not limited to the above step motor, but may be a DC motor or any type thereof.

[0039]

As described above, according to the present invention, even if the lead screw is configured to be as short as possible in the axial direction, the stability can be sufficiently improved by setting the deformation amount of the biasing force of the preload mechanism with respect to the lead screw to be larger. Therefore, it is possible to provide a motor with a lead screw which can secure a high speed response by reducing the detent torque, and can prevent an unreasonable force from acting on the bearing to prolong the service life.

[0040]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part showing a main part of a motor with a lead screw according to a first embodiment.

FIG. 2 is a cross-sectional view of essential parts showing a modified example of the motor with lead screw of the embodiment of FIG.

3 is a cross-sectional view of essential parts showing a modified example of the motor with lead screw of the embodiment of FIG.

FIG. 4 is a cross-sectional view of essential parts showing a modified example of the motor with lead screw of the first embodiment.

FIG. 5 is a cross-sectional view of essential parts showing a modified example of the motor with lead screw of the first embodiment.

FIG. 6 is a cross-sectional view of a main part showing a main part of a motor with a lead screw according to a second embodiment.

FIG. 7 is a cross-sectional view of essential parts showing a modified example of the motor with lead screw of the embodiment of FIG. 6.

FIG. 8 is a cross-sectional view of essential parts showing a modified example of the motor with lead screw of the second embodiment.

FIG. 9 is a cross-sectional view of essential parts showing the middle of assembly of the motor with lead screw of the second embodiment.

FIG. 10 is a schematic diagram for explaining the operation of the motor with lead screw of the embodiment.

FIG. 11 is a schematic diagram for explaining an operation of a motor with a lead screw of a conventional example.

[Explanation of symbols]

 1 base 2 pivot bearing 3 bearing 5 lead screw 6 mounting plate 7 permanent magnet 8 coil (stator) 9 compression coil spring (biasing means) 10 rod-shaped member (pressing member) 11 cover member 12 bearing 20 carriage 32 male bearing body

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yukinori Arai 2-16-20 Shimura, Itabashi-ku, Tokyo Inside Copal Co., Ltd.

Claims (4)

[Claims] 1. In order to eliminate looseness in the axial direction, one end is rotatably supported in the axially immovable state, and the other end is rotatably supported by being urged in the axial direction. A lead screw motor in which a lead screw groove is formed and a lead screw is provided on the output shaft, the bottomed hole portion having an inner diameter portion formed concentrically at the other end of the lead screw; An urging member provided in the bottom hole portion, and inserted into the bottomed hole portion subsequent to the urging member, and a bottom surface of the urging member contacts the urging member and at least a spherical surface on a surface facing the bottom surface. And a pressing member that abuts against the spherical surface and is held in the biased state, and partially sunk into the inner diameter portion to axially support or partially protrude from the other end. Pivot It comprises a bearing member, the lead screw with the motor, characterized in that configured for supporting the both ends of the lead screw. 2. The bearing member is fixed to a lid body fixed to the other end of an annular stator, one end of which is fixed in a mounting portion that inserts an intermediate portion of the lead screw into an inserted state. The motor with lead screw according to claim 1. 3. The motor with a lead screw according to claim 2, wherein the bearing member is fixed so as to be substantially fitted to the inner peripheral surface of the stator. 4. The motor with a lead screw is provided with an engaging portion that engages with the feed screw groove portion in order to use a recording or reproducing head for tracking drive on a disc-shaped recording medium,
5. The carriage according to claim 1, further comprising a carriage that is movably arranged in parallel with the lead screw and that mounts the recording or reproducing head.
A motor with a lead screw according to the item.