JPH0280908A - Friction feed mechanism - Google Patents

Abstract

PURPOSE:To perform positioning with high accuracy by small-sized simple constitution by constituting a magnetic circuit between a drive shaft and a friction roller and obtaining the pressing force of the drive shaft with the friction roller whose lead angle is made changeable by utilizing the magnetic force of the magnetic circuit. CONSTITUTION:A magnetic circuit containing a friction roller 48, a drive shaft 12 and a holding member 42 is usually constituted of permanent magnets 51A, 51B, and the roller 48 and the shaft 12 are attracted mutually to generate pressing force. When a current is supplied to shape memory wires 62A, 62D in this state, a revolving shaft 43 is revolved and a revolving plate 63 strikes on a stopper 66A and the lead angle of the roller 48 is set to fine adjustment feed. Herein, a current is supplied to the piezoelectric element 73 of a lock means 71 to displace the same and the revolution of the shaft 43 is prescribed. When a current is supplied to shape memory wires 62B, 62C, the plate 63 strikes on a stopper B and the lead angle of the roller 48 is set to high speed feed. By this method, positioning can be performed with high accuracy by small-sized simple constitution.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a friction feeding mechanism using friction rollers.

For example, it can be used as a table or head feeding mechanism for measuring machines, machine tools, etc.

[Prior Art] Coordinate measuring machines, machine tools, and the like are configured to relatively move a table on which a work is placed, a probe, or a head that supports a tool using a feeding mechanism.

Conventionally, this type of feed AM requires highly accurate feed, and therefore a system has often been used in which a feed screw such as a ball screw is used to convert the rotational motion of the drive shaft into reciprocating motion in the axial direction. However, this method has the problem of high manufacturing costs because the thread shape formed on the drive shaft must be finished with high precision.

Therefore, a friction roller that is inclined at a predetermined lead angle with respect to the axis of the drive shaft is pressed against the circumferential surface of the drive shaft, and the feeding operation is performed using the axial component force of the drive shaft that is generated on the friction roller as the drive shaft rotates. A friction feed R bucket has been developed that performs 6 For example, the 4th
What is shown in FIG. 5 or FIG. 5 has been developed.

The one shown in FIG. 4 includes a relatively movable bed (not shown) and a table 2, with a drive shaft 3 on the bed side.
is rotatably provided along the moving direction of the table 2, and a roller holding member 5 is rotatably attached to the table 2 side via the support member 4 with a support shaft 6 as a fulcrum. A friction roller 7 inclined at a predetermined lead angle with respect to the axis of the drive shaft 3 is rotatably mounted, and the friction roller 7 is pressed against the circumferential surface of the drive shaft 3 between the table 2 and the roller holding member 5. This configuration includes a tension coil spring 8.

In addition, the one shown in FIG. 5 has a support member 4A on the table 2.
, 4B, a pair of roller holding members 5A and 5B are mounted on both sides of the drive shaft 3 and rotatably about support shafts 6A and 6B, respectively, and each roller holding member 5A,
5B, friction rollers 7A, 7 which are inclined at a predetermined lead angle with respect to the axis of the drive shaft 3 and at the same lead angle.
B are rotatably attached to each other, and a tension coil spring 8- for pressing both friction rollers 7A, 7B against the circumferential surface of the drive shaft 3 is provided between both roller holding members 5A, 5B.

[Problems to be Solved by the Invention] In the configuration shown in FIG. It will work. This reaction force causes disturbance to the guide mechanism of the table 2, and is a factor that impedes highly accurate positioning. Therefore, in the past, in order to receive this reaction force, the guide a mechanism of the table 2 had to have high rigidity, which caused the problem of increasing the size of the mechanism.

Furthermore, in the configuration shown in FIG. 5, since the pair of friction rollers 7A and 7B are pressed by the tension coil springs 8- from both sides of the drive shaft 3, their reaction forces cancel each other out and do not act on the outside. There are some advantages. However, such a mechanism requires a pair of friction rollers 7A and 7B, which makes the mechanism complicated. Furthermore, it is extremely difficult to match the lead angles of the friction rollers 7A and 7B with respect to the axis of the drive shaft 3.If the lead angles of the friction rollers 7A and 7B are even slightly different from each other, a lead error will occur. As a result of slippage on the drive shaft 3, not only can highly accurate positioning not be expected, but there are also problems with durability.

By the way, in order to vary the feed speed in such a friction feed m mechanism, it is necessary to have a configuration in which the lead angle of the friction roller with respect to the axis of the drive shaft 3 can be adjusted, or
It is known that a plurality of sets of friction rollers having different lead angles with respect to the axis of the drive shaft 3 are provided and configured such that these rollers can be selectively pressed against the outer peripheral surface of the drive shaft 3.

However, in the former case, since the friction roller is pressed against the outer peripheral surface of the drive shaft 3 by the tension coil spring 8.8-, it is not easy to change the lead angle, and the pressing force is A means to release the restriction is necessary. Moreover,
In the configuration shown in FIG. 5, a pair of friction rollers 7A,
It is more difficult because the lead angles of 7B must be changed equally.

Furthermore, in the latter case, it is necessary to provide a plurality of sets of friction rollers with different lead angles, which has the drawback of complicating the structure and increasing the size of the device.

The purpose of the present invention is to solve these conventional problems, and there is no need to process the reaction force without using a plurality of I'J rubbing rollers, and therefore it is small and simple. It is an object of the present invention to provide a friction feed mechanism that can achieve highly accurate positioning with a simple configuration and can also vary the feed rate with a simple configuration.

[Means for Solving the Problems] Therefore, in the present invention, in order to downsize and simplify the mechanism, the lead angle of the friction roller can be varied with respect to the axis of the drive shaft, and the friction roller A magnetic circuit is formed between the roller and the roller, and the magnetic force of this magnetic circuit is used to obtain a pressing force.

Specifically, one of the two relatively movable members is provided with a drive shaft made of a magnetic material so as to be rotatable along the direction of relative movement, and the other of the two relatively movable members is provided with a peripheral surface or the drive shaft. A friction roller made of a magnetic material that is placed in contact with or slightly apart from the circumferential surface of the shaft can be rotated, and can be rotated around a rotation axis that is orthogonal to the axis of rotation of the roller and the axis of the drive shaft. A magnetic circuit is provided between the drive shaft and the friction roller, and a rotating means for rotating the rotating shaft and a locking means for locking the rotating shaft at a plurality of rotation angle positions are provided. It is characterized by:

1 action] Drive shaft and I! Since a magnetic circuit is constructed between the roller and the J rubbing roller, a pressing force is obtained by the magnetic force of the magnetic circuit. Since the pressing force is not obtained by mechanical urging means as in the conventional case, there is no need to deal with reaction force. Therefore, the guide mechanism does not need to have high rigidity in order to receive the reaction force, and it is not necessary to use a plurality of friction rollers, so the structure can be small and simple.

Moreover, there is no need to use multiple friction rollers.
Since there is no problem of slippage due to these lead errors, highly accurate positioning can be achieved.

Further, by rotating the rotating shaft using the rotating means, the lead angle of the friction roller with respect to the axis of the drive shaft can be changed, so that the feed rate can be varied. Moreover, since the rotation of the rotation shaft can be restricted by the locking means, the feed operation can be performed accurately at a feed speed corresponding to the set lead angle.

[Example] Hereinafter, the present invention will be explained in detail based on examples.

FIG. 1 is a cross section showing the main part of this embodiment, and FIG. 2 is a plane view thereof. In this embodiment, the table is applied to a table feeding device, and as shown in FIG. 2
1 is provided so as to be able to reciprocate in the left and right directions in FIG.

One side of these two relatively moving members, here the bed 1
On the first side, a drive shaft 12 made of a magnetic material is provided so as to be rotatable along the reciprocating direction of the table 21. The drive shaft 12 is rotatably supported at both ends by brackets 13 (the left end in FIG. 1 is not shown) provided on the bed 11, and is rotationally driven by a motor 14 connected to one end.

On the other hand, a holding member 42 made of a magnetic material is attached to the table 21 side via a bracket 41. At the center position of the holding member 42, there is a rotation shaft 43 or the drive shaft 1.
A rotation block 45 having a =1 shape is integrally provided at the lower end of the zero rotation shaft 43, which is rotatably provided at right angles to the axis of FIG. Therefore, the rotation block 45 is also rotatable together with the rotation shaft 43. Note that 46 is a thrust bearing interposed between the upper surface of the rotating block 45 and the holding member 42, and 47 is a disc spring. The disc spring 47 holds the upper surface of the rotation block 45 against the holding member 42.
The thrust bearing 46 is for reducing the rotation resistance of the rotation block 45.The rotation block 45 has a friction roller 48 formed of a magnetic material. is rotatably supported via a bearing (not shown).

The friction roller 48 has a circumferential surface that is in contact with or slightly apart from the circumferential surface of the drive shaft 12, and has an axis that is perpendicular to the rotational axis of the friction roller 48 and the axis of the drive shaft 12. It is possible to rotate around the center. In other words, it is configured to be rotatable around the rotating shaft 43.

Permanent magnets 51A and 51B, which form a magnetic circuit between the drive shaft 12 and the rubbing roller 48, are attached to both sides of the lower surface of the holding member 42, respectively. The lower end portion of each of the permanent magnets 51A, 51B is formed into an arcuate recessed portion having a large gap with respect to the outer peripheral surface of the drive shaft 12.

Further, the rotation shaft 43 is provided on the upper surface side of the holding member 42.
A rotation means 61 for rotating the rotation shaft 43 and a locking means 71 for locking the rotation shaft 43 at a plurality of rotation angle positions are provided.

The rotating means 61 is composed of four shape memory wires 62A to 62D that contract when energized. The shape memory wires 62A and 62D and 62B and 62C are arranged diagonally across the rotation shaft 43 and parallel to the axis of the drive shaft 12. That is, each of the shape memory wires 62A to 62D is wound around four front and rear rollers 64 provided at the upper end of the rotation shaft 43 via a rotation grate 63, and both ends of each of the shape memory wires 62A to 62D are connected to the holding member. 4
2, respectively, are connected to locking members 65 provided at both ends. Therefore, the rotation shaft 43 is shaped like the shape memory wire 62B.
, 62C rotate counterclockwise in FIG. 2, and when power is applied to the shape memory wires 62A and 62D, they rotate clockwise in FIG. 2.

Here, when the rotation shaft 43 is rotated clockwise in FIG. 2 by energizing the shape memory wires 62A and 62D and the rotation plate 63 comes into contact with the stopper 66A, the rotation shaft 43 is rotated clockwise in FIG.
), the rotational axis of the friction roller 48 is aligned with the drive shaft 12.
The lead angle is set in advance to be a lead angle θ1 with respect to the axis. Further, when the rotating shaft 43 is rotated counterclockwise in FIG. 2 by energizing the shape memory wires 62B and 62C and the rotating plate 63 comes into contact with the stopper 66B, the third
As shown in Figure (B), the opening means 71 is set in advance so that the axis of rotation of the friction roller 48 is at a lead angle θ2 (θ1 × θ2) with respect to the axis of the drive shaft 12. It is composed of grooves 72 formed on the upper surface of the holding member 42 corresponding to both end portions of the moving plate 63, and piezoelectric elements 73 that are accommodated in each groove 72 and are displaced in the vertical direction when energized. Therefore, when the piezoelectric element 73 is energized, the piezoelectric element 73 is displaced in the vertical direction. Then, the rotating plate 63 is pressed upward, and the rotating block 43 moves upward.
Since the friction between the upper end surface of the holding member 42 and the holding member 42 increases, rotation of the rotating shaft 43 is restricted.

Next, the operation of this embodiment will be explained.

Normally, the friction roller 4 is moved by permanent magnets 51A and 51B.
8. Since a magnetic circuit including the drive shaft 12 and the holding member 42 is configured, the friction roller 48 and the drive shaft 12 are attracted to each other by the magnetic force of the magnetic circuit. In other words, a pressing force is generated by this suction force.

((Movement feed) To move the table 21 slightly relative to the bed 11,
Electricity is applied to the shape memory wires 62A and 62D. Then, the rotation shaft 43 is rotated clockwise in FIG. 2, and the rotation plate 63 comes into contact with the stopper 66A. In this state, the rotational axis of the friction roller 48 is set at an angle inclined at a lead angle θ1 with respect to the axis of the drive shaft 12, as shown in FIG. 3(A).

Here, when the piezoelectric element 73 of the locking means 71 is energized,
Since the piezoelectric element 73 is displaced in the vertical direction and the friction between the upper end surface of the rotation block 43 and the lower surface of the holding member 42 increases, rotation of the rotation shaft 43 is restricted at a set angular position.

Therefore, in this state, the drive shaft 1 is
When 2 is rotated, 1ll follows the rotation of the drive shaft 12.
Since the i-roller 48 rotates, the table 21 is moved at a feed pitch P1πd tan θ1 (d is the diameter of the drive shaft 12) according to the lead angle θ1. In other words,
The table 21 can be slightly moved relative to the bed 11 at a feed pitch P1.

(High-speed feed) To feed the table 21 at high speed with respect to the bed 11,
Electricity is applied to the shape memory wires 62B and 62C. Then, the rotation shaft 43 is rotated counterclockwise in FIG. 2, and the rotation plate 63 comes into contact with the stopper 66B. In this state, as shown in FIG. 3(B), the rotational axis of the friction roller 48 is set at an angle inclined with respect to the axis of the drive shaft 12 at a lead angle θ2.

Here, when the piezoelectric element 73 of the locking means 71 is energized,
Since the piezoelectric element 73 is displaced in the vertical direction and the friction between the upper end surface of the rotation block 43 and the lower surface of the holding member 42 increases, the rotation of the rotation shaft 43 is restricted at a set angular position.

Therefore, in this state, the drive shaft 1 is
2, the friction roller 48 rotates following the rotation of the drive shaft 12, so the table 21 has a lead angle θ2.
Feed pitch P1πd tanθ2 according to (however,
d is the diameter of the drive shaft 12). In other words, the table 21 can be fed at high speed with respect to the bed 11 at the feed pitch P2.

Therefore, according to this embodiment, since a magnetic circuit is constructed between the drive shaft 12 and the friction roller 48 using the permanent magnets 51A51B, the friction roller is pressed from one side of the drive shaft as in the conventional case. There is no need to deal with the reaction force that occurs when this occurs, which means that the guide mechanism for receiving the reaction force does not need to have high rigidity as in the past, and
Since there is no need to use a plurality of friction rollers, the structure can be made smaller and simpler. Moreover, since the friction rollers 34A and 34B do not need to be mechanically displaced, the structure can be simplified from this point as well.

Furthermore, since it is not necessary to use a plurality of friction rollers to process the reaction force, there is no problem of slippage due to these lead errors, and highly accurate positioning can be achieved.

Further, one friction roller 48 is provided rotatably around a rotation shaft 43 that is orthogonal to its rotation axis and the axis of the drive shaft 12, and a rotation means for rotating the rotation shaft 43 is provided. 61 is provided, by rotating the rotating shaft 43 by the rotating means 61, the lead angle that the rotational axis of the friction roller 48 makes with respect to the axis of the drive shaft 12 can be changed. and high-speed feed can be easily switched. Moreover, since the rotating means 61 is constituted by the four shape memory wires 62A to 62D, the structure can also be made smaller. For example, it can be much smaller than using a motor.

Further, since the locking means 71 for locking the rotating shaft 43 at a predetermined angular position is provided, the set lead angle θ1. θ2 can be maintained accurately. Therefore, accurate feeding can be achieved. Furthermore, since the locking means 71 is also constituted by the piezoelectric element 73, it can be expected that the size will be reduced from this point of view as well.

In other words, it can be much smaller than the case where it is constructed using cylinders.

In the above embodiment, the magnetic circuit is configured by the permanent magnets 35A and 35B, but the present invention is not limited to this, and for example, an electromagnet may be used.

Further, in the above embodiment, the means 61 for rotating the rotation shaft 43
Although the four shape memory tires 62A to 62D are used, the present invention is not limited thereto, and a motor or the like may be used instead.

Further, in the above embodiment, the locking means 71 that restricts the rotation of the rotation shaft 43 is constituted by the piezoelectric element 73, but is not limited thereto, and may be a cylinder, for example.

Further, the motor 14 is not limited to one driven at a constant rotation speed, and may be a motor with variable rotation speed. In this way, a wider range of feed speed changes can be obtained with a simple structure. .

Note that the present invention is not limited to the table feeding device described in the above embodiment, but may be applied to a column and head of a machine tool, for example, and can be applied to general feeding mechanisms of two members that move relative to each other.

[Effects of the Invention] As described above, according to the present invention, it is not necessary to process reaction force without using a plurality of friction rollers, and therefore high-precision positioning can be achieved with a small and simple configuration, and the feed speed can be improved. It is possible to provide a friction feed R lateral whose speed can also be varied with a simple configuration.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
The figure is a front view with a part of the main part cut away, FIG. 2 is a plan view thereof, and FIGS. 3A and 3B are plan views showing the relationship between the drive shaft and the friction roller. FIGS. 4 and 5 are perspective views showing conventional examples, respectively. 11.21... Bed and table, (two members movable relative to each other) 12... Drive shaft, 48... Friction roller, 51A, 51B... Permanent magnet, (means for configuring a magnetic circuit) 1 ... Rotating means, ... Locking means.

Claims (1)

[Claims] (1) A drive shaft made of a magnetic material is provided on one of the two relatively movable members so as to be rotatable along the direction of relative movement, and the other of the two relatively movable members is provided with a circumferential surface of the drive shaft. A friction roller made of a magnetic material that is placed in contact with or slightly apart from the circumferential surface is rotatably provided and is rotatable around a rotation axis perpendicular to the axis of rotation thereof and the axis of the drive shaft. , a magnetic circuit is configured between the drive shaft and the friction roller, and a rotating means for rotating the rotating shaft and a locking means for locking the rotating shaft at a plurality of rotation angle positions are provided. A friction feed mechanism characterized by: