JPH05176496A - Mechanism for converting rotary motion into linear motion - Google Patents

Abstract

PURPOSE:To reduce mechanical loss due to friction by a method wherein a moving body is moved linearly and reciprocally through magnetic force generated by the rotation of a magnetic body. CONSTITUTION:When a servomotor 7 is rotated based on a given control, the rotation is transmitted to a rotary shaft 2 through a gear train 8. A spiral magnetic body 10 is rotated by the rotation of the rotary shaft 2 while a magnet 12, opposed to the top surface 10a of the magnetic body 10, moves linearly along a guide groove 11a by the attractive force of the magnet 12. As a result, the moving body 5 moves linearly on a box body 11. The top surface 10a of the magnetic body 10 is in a condition of non-contact with the tip end 12a of the magnet 12 whereby friction will never be caused and the moving body 5 can effect smooth straight-line motion. According to this method, mechanical loss due to friction can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary linear conversion mechanism, and more particularly to a novel improvement for reducing mechanical loss due to friction as much as possible.

[0002]

2. Description of the Related Art Conventionally, there is a ball screw 1 as shown in FIG. 2 which has been favorably used for positioning by numerical control of a machine tool. The ball screw 1 has a configuration in which a plurality of balls 4 are arranged between a rotary shaft 2 having a spiral groove 2a formed on the outer circumference thereof and a nut portion 3 having a spiral groove 3a formed on the inner circumference thereof. The ball screw 1 is, as shown in FIG.
It is used as a part of a rotary linear conversion mechanism 6 that linearly reciprocates the moving body 5 fixed to the nut portion 3.
The rotation straight line conversion mechanism 6 includes a servomotor 7 for rotating the rotation shaft 2 of the ball screw 1 in the normal direction or the reverse direction. The servomotor 7 is provided with the rotation shaft 2 via a gear train 8 forming a reduction mechanism. Is linked to. Therefore, the rotary shaft 2 rotates following the rotation of the servomotor 7, and the nut portion 3 and the moving body 5 linearly move in the axial direction of the rotary shaft 2 accordingly.

[0003]

Since the conventional rotary straight line conversion mechanism 6 is constructed as described above, the following problems exist. That is, the ball screw 1 used in the rotation linear conversion mechanism has much less friction than a general sliding contact type screw, but the mechanical efficiency is still about 95% and the friction of about 5%. Losses will occur. Further, since the balls 4 are in mechanical contact with the spiral grooves 2a and 3a, the movement error of the moving body 5 increases with the wear amount of the balls 4 and the spiral grooves 2a and 3a, and the life is limited. There was a problem that they would be caught.

The present invention has been made to solve the above problems, and in particular, it is an object of the present invention to provide a rotary linear conversion mechanism that reduces mechanical loss due to friction as much as possible. .

[0005]

According to the present invention, there is provided a rotary straight line conversion mechanism, in which a spiral magnetic body integrally provided with a rotary shaft which is rotated by a motor and which is opposed to the magnetic body. The moving body is provided so as to be linearly movable, and the magnet is provided on the moving body and is kept in a non-contact state with the magnetic body. It is configured to be possible.

[0006]

In the rotary straight line conversion mechanism according to the present invention, the rotating shaft is rotated by the motor, so that the magnetic body is spirally provided around the rotating shaft and the magnet is maintained in a non-contact state with the magnetic body. By the suction action of and, the moving body provided with the magnet linearly moves following the rotation of the rotating shaft due to the rotation of the motor, so that mechanical loss due to friction can be reduced as much as possible.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the rotary straight line conversion mechanism according to the present invention will be described in detail below with reference to the drawings. It should be noted that the same or equivalent portions as those of the conventional example will be described using the same reference numerals.

As shown in FIG. 1, reference numeral 10 is a ferromagnetic material which is integrally formed in a spiral shape on the outer periphery of a cylindrical rotating shaft 2. The ferromagnetic body 10 and the rotating shaft 2 are provided in a housing 1
1 is rotatably housed in the upper part of the housing 11,
A trapezoidal moving body 5 is mounted movably in a straight line via a linear guide groove 11a facing the magnetic body 10.

A permanent magnet 12 is arranged between the moving body 5 and the spiral top surface 10a of the ferromagnetic body 10, and the magnet 12 is fixed to the bottom of the moving body 5. The tip portion 12a of the magnet 12 is placed so as to be separated from the top surface 10a of the magnetic body 10 by a predetermined distance so as to maintain a non-contact state, and the guide groove 1 is placed in the housing 11.
It is inserted so as to be linearly movable along 1a. Therefore, the moving body 5 can be moved linearly following the movement of the magnetic body 10. Reference numeral 7 is a servo motor, and reference numeral 8 is a gear train forming a reduction mechanism.

The operation of the above configuration will be described below. When the servo motor 7 is rotated under a certain control, this rotation is transmitted to the rotary shaft 2 via the gear train 8. The rotation of the rotary shaft 2 causes the spiral magnetic body 10 to rotate, and the magnet 12 that follows the top surface 10a of the magnetic body 10 is linearly moved along the guide groove 11a by its attractive force. Moving. As a result, the moving body 5 linearly moves on the housing 11, and the magnetic body 10 is moved.
Since the top surface 10a of the magnet 10 and the tip portion 12a of the magnet 12 are not in contact with each other, friction does not occur, and a smooth linear motion is provided to the moving body 5.

The present invention is not limited to the above-mentioned embodiment, and the moving speed of the moving body 5 can be changed by changing the individual spiral pitch of the magnetic body 10, for example. That is, assuming that the rotation of the servomotor 7 is constant, if the spiral pitch is lengthened, the moving speed of the moving body 5 can be increased at that portion, and conversely, if the spiral pitch is shortened, the moving speed is increased. The moving speed of the body 5 can be reduced. Further, as shown in FIG. 1, by changing the surface area of the top surface 10a of the magnetic body 10, the attraction force with the magnet 10 can be changed,
By making the magnet 10 an electromagnet, a stronger attraction force can be generated and the linear reciprocating movement of the moving body 5 can be further stabilized.

[0012]

Since the rotary linear conversion mechanism according to the present invention is constructed as described above, the following effects can be obtained. That is, since the magnetic body spirally wound around the rotating body and the magnet fixed to the moving body are always in non-contact with each other, the mechanical loss due to friction can be reduced as much as possible. The linear movement can be made smoother.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a rotary straight line conversion mechanism of the present invention.

FIG. 2 is a cross-sectional view showing a conventional rotary straight line conversion mechanism.

FIG. 3 is an enlarged sectional view showing a main part of FIG.

[Explanation of symbols]

 2 rotating body 5 moving body 6 rotation linear conversion mechanism 7 motor 10 magnetic body 12 magnet

Claims (1)

[Claims] 1. A spiral magnetic body (10) integrally provided with the rotating shaft (2) around the rotating shaft (2) rotated by a motor (7), and the magnetic body (10). The magnetic body (5) is provided so as to face each other and is linearly movable, and a magnet (12) provided on the mobile body (5) and kept in a non-contact state with the magnetic body (10). 10) Rotation of the moving body (5) through the magnet (12)
A rotary straight line conversion mechanism characterized by being configured to be capable of linearly reciprocating.