JPH09158949A - Driving gear for linear bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold balance and bear a reverse direction load by easily following a change of external force of a movable body and improve speed accuracy without being influenced by a motional direction and a speed change of a swiveling member. SOLUTION: A direct acting gas bearing 14 linearly moving a movable unit 20 guided by a fixed unit 19 and a linear driving gear 13 of the movable unit 20 are concurrently provided, further a voice coil motor 15, generating thrust in a reverse direction balanced with one-way external force (for instance, gravitational force) applied to the movable unit 20, is arranged. Unbalance of force can be easily adjusted by controlling a current value of the voice coil motor 15 to generate a reverse force to the gravity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a drive device for a linear motion bearing used in various precision measuring devices and the like.

[0002]

2. Description of the Related Art As a conventional device of this type, those shown in FIGS. 8 and 9 are generally known. This is a feed screw device 3 as a linear drive device in which a column 2 is erected vertically on a base 1 and is vertically supported by the column 2.
And the direct-acting gas bearing 4 are installed in parallel. Motor 5
The nut 7 screwed onto the screw shaft 6 of the feed screw device 3 which is rotationally driven by is directly connected to the movable body (slider) 8 of the linear motion gas bearing 4 and is connected thereto. When the screw shaft 6 of the feed screw device 3 is rotated by the motor 5, the nut 7 vertically moves vertically according to the rotation direction, and the movable body 8 of the linear motion gas bearing 4 moves along with the fixed body 9 along with the linear movement of the nut 7. Guided by Nut 7
Move straight in the same direction as.

For example, a measuring head of a precision measuring device is mounted on the movable body 8 and moved vertically by the driving force of a driving motor 5 to convey the measuring head or the like and precisely control it at a predetermined position. Can be used for positioning. In that case, in order to improve controllability, it is desirable that the driving force of the motor 5 be constant in the upward and downward directions. As a conventional means for improving controllability, it is general to connect a counterweight 10 having the same weight as that of the movable body 8 by using a wire rope 10w of a swinging member guided by a rotatable pulley 10p. is there. As a result, a force in the antigravity direction is applied to the movable body 8 to eliminate the imbalance of the axial force.

[0004]

However, in the above-described conventional linear motion bearing drive device, when the weight of the movable body 8 changes due to replacement of the mounted measuring head or the like, each time. Since it is necessary to change the weight of the counterweight 10 as well, the counterweight 10 must be newly manufactured or attached, which requires not only the cost and time for that, but also the fine adjustment of the balance. There is a problem that is difficult.

Further, since an object having the same weight as the external force of the movable body 8 is hung, there is a problem that the total weight increases and it becomes difficult to reduce the weight of the apparatus. Furthermore, since the movement direction and speed of the swinging member (wire rope 10w) change during linear movement, as a result, torque fluctuations of the pulley 10p and a small amount of expansion and contraction due to elastic deformation of the swinging member occur, resulting in a balance. There is a problem in that the balance changes delicately and the speed accuracy deteriorates.

Therefore, according to the present invention, the change of the external force of the movable body is easily followed, the load is applied in the opposite direction to maintain the balance, and the speed accuracy is not affected by the movement direction of the rocking member or the speed change. It is an object of the present invention to provide an improved linear motion bearing drive device.

[0007]

According to a first aspect of the present invention, a linear bearing in which a movable body is linearly moved by being guided by a fixed body and a linear drive device for the movable body are provided side by side. A dynamic coil drive device is provided with a voice coil motor that generates thrust in a reverse direction that balances with external force in one direction applied to the movable body.

The invention according to claim 2 of the present invention is
The present invention relates to a linear motion bearing driving device in which a linear motion bearing for linearly moving a movable body guided by a fixed body and a linear driving device for the movable body are provided side by side, and is balanced with an external force in one direction applied to the movable body. An air cylinder for generating thrust in the opposite direction and transmitting the thrust to the movable body is provided. Further, the invention according to claim 3 of the present invention relates to a linear motion bearing drive device in which a linear motion bearing for linearly moving a movable body guided by a fixed body and a linear drive device for the movable body are provided side by side. ,
It is characterized in that it is provided with a rotary motor which generates a torque in a reverse direction to balance an external force applied to the movable body in one direction and transmits the torque to the movable body via an oscillating member.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a front view of a first embodiment of the present invention, and FIG. 2 is a plan view. First, the structure will be described. A support 12 is vertically installed on a base 11, and the support 1
A feed screw device 13 as a linear drive device is vertically supported by support bases 12a and 12b that horizontally extend above and below the two. Further, a direct acting gas bearing 14 as a direct acting bearing is provided side by side in parallel with the feed screw device 13 and is supported by the column 12. Further, a voice coil motor (VC), which is a linear motor, is provided adjacent to the linear motion gas bearing 14.
M) 15 is also vertically attached to the column 12.

The feed screw device 13 need not be limited in type, but the one shown in the drawing uses, for example, a circulating tube type ball screw device. That is, the supports 12a and 12b
The screw shaft 16 rotatably supported at the top and bottom has a ball screw groove on the outer peripheral surface, and a ball nut 17 having a ball screw groove on the inner peripheral surface facing the ball screw groove of the screw shaft. Is screwed through a large number of balls (not shown) fitted between the ball screw grooves, and these balls roll in the groove as the screw shaft 16 is rotated by the screw shaft drive motor 18 while rotating the ball nut. It is configured to circulate through a circulation tube (not shown) provided at 17.

It is not necessary to limit the type of the direct acting gas bearing 14 either, but the illustrated one uses, for example, a porous static pressure gas bearing. That is, the outer surface formed by the four planes of the prismatic fixed body 19 whose upper and lower sides are fixedly supported by the support bases 12c and 12d is the receiving surface, and the rectangular frame-shaped movable body surrounding the fixed body 19 is attached. 20 has a bearing surface on the inner surface formed of four flat surfaces facing the receiving surface of the fixed body 19 with a bearing gap therebetween. A porous material (not shown) is attached to the bearing surface of the movable body 20, and the compressed gas supplied through the ventilation holes provided in the movable body 20 passes through the fine pores in the porous material to an appropriate pressure. After being squeezed, it squirts from the bearing surface into the bearing gap to form a fluid film, whereby the movable body 2
0 is supported on the fixed body 19 in a non-contact manner by restraining it on all four sides. Ball nut 17 of the feed screw device 13
Is connected to one side surface of the movable body 20 of the linear motion gas bearing 14 via the connecting member 17A.

The voice coil motor 15 loses the balance of the vertical force due to the influence of gravity acting on the movable body 20 of the linear motion gas bearing 14, and the feed screw device 13 positions and moves the movable body 20 up and down. It is provided as a means for preventing the controllability of speed from decreasing, and its type does not need to be particularly limited. One of the coil and the magnet is the mover and the other is the stator, but the one shown in the figure uses, for example, the mover 22 as a coil and the stator 23 as a magnet, and the yoke of the stator 23 is used. It is sandwiched by magnets fixed to the inner surface of the coil, and the coil of the mover 22 is arranged so as to face each other in a non-contact manner via a gap. The bobbin around which the coil of the mover 22 is wound and the other side surface of the movable body 20 of the linear motion gas bearing 14 are integrally connected.

Next, the operation will be described. Screw shaft drive motor 1
When 8 is rotated, the screw shaft 16 of the feed screw device 13 rotates. The rotation of the screw shaft 16 causes the ball nut 17 connected to the movable body 20 of the linear motion gas bearing 14 and the screw shaft 1 to rotate.
6 is converted into a linear movement of the ball nut 17 through a spiral movement of a ball interposed between the ball nut 17 and the ball 6. This allows
The movable body 20 of the linear motion gas bearing 14 is guided by the fixed body 19 and moves vertically.

At this time, gravity (external force) acting on the movable body 20 itself is applied to the ball nut 17 as a downward unbalanced load, and if it is left as it is, a required torque for forward and reverse rotation of the screw shaft drive motor 18 is maintained. Are different from each other, and a difference occurs in the speed when the movable body 20 descends and when the movable body 20 rises, resulting in a situation in which the positioning accuracy and speed accuracy of the device are reduced. However, according to this embodiment, the voice coil motor 15 pulls up the movable body 20 with the thrust of the same magnitude as the gravity acting on the movable body 20 and in the opposite direction, and the voice coil motor 15 accompanies while keeping the balance and vertically. Move to.

The magnitude of the pulling force (thrust) is determined by the following equation from the thrust constant of the voice coil motor 15 and the current value. Pulling force [kg] = Thrust force constant [kg / A] × Current [A] That is, the fine adjustment of the pulling force is easily performed by changing the current value of the voice coil motor 15 (or changing the thrust constant). It is possible.

Thus, according to the drive device for the linear motion gas bearing of the first embodiment, even if the external force acting on the movable body 20 changes, the weight of the counterweight changes each time as in the conventional case. There is no need to perform the troublesome and costly and time-consuming adjustment, and the effect that the fine adjustment of the balance can be easily and highly accurately performed by the electric adjustment can be obtained.

Further, since the movable body 20 is levitationally supported in a substantially weightless state without using a counterweight, the weight of the apparatus can be reduced and weight reduction can be achieved. Furthermore, a rocking member (wire rope 10W) that elastically deforms and expands and contracts as in the conventional case
Since there is no need to use, there is no room for the phenomenon that the balance of balance is subtly changed and the speed accuracy is deteriorated, and positioning and speed accuracy are improved with a stable stroke.

A second embodiment is shown in FIGS. The same parts as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted. In this embodiment,
As a means for preventing the controllability of the movable body 20 from deteriorating due to the influence of gravity acting on the movable body 20 of the linear motion gas bearing 14, an air cylinder 30 is fixed to the column 12 instead of the voice coil motor 15. Is different from the first embodiment.

As the air cylinder 30, a so-called rodless cylinder having no piston rod is used. The outline thereof will be described with reference to FIG.
1 has a slit in the axial direction, but two flexible seal belts 32, one inside and one outside, stretched across the slit,
By sealing with 33, the airtightness is maintained.
The piston 34 is integrally connected to an external movable table 36 via a piston yoke 35 that protrudes out of the cylinder through the slit. Piston yoke 35
On the upper surface of the guide groove 37 for passing the outer seal belt 32
However, a guide groove 38 for passing the inner seal belt 33 is formed on the lower surface.

The piston 3 is fed by sending compressed air into the cylinder.
When 4 is operated, the movable table 36 moves together with the piston 34 while separating the seal belts 32 and 33 by the piston yoke 35. Both seal belts 32 and 33 are integrally joined again as the piston yoke 35 passes, and seal along with the operation of the piston 34.

The movable table 3 of the air cylinder 30 described above.
6 is integrally connected to the other side surface of the movable body 20 of the linear motion gas bearing 14 to apply an upward pushing force that balances the downward load of the movable body 20. The pushing force is determined by the inner diameter of the cylinder tube 31 of the air cylinder 30 and the supply pressure. The fine adjustment of the pushing force can be easily performed by adjusting the supply pressure to the air cylinder 30 with an air regulator. Further, the pushing force can be adjusted by changing the diameter of the cylinder tube 31 as needed.

There is an advantage that the cost can be reduced by using an air cylinder lower in cost than the voice coil motor. Other functions and effects are similar to those of the first embodiment. The movable table 36 of the rodless cylinder of the type described above and the movable body 20 can be connected by using a swing member such as a wire or a rope.

The air cylinder is not limited to the rodless cylinder, but may be a cylinder with a rod. But,
Since the rodless cylinder has a shorter axial length than the cylinder with a rod, there is an advantage that the mounting space is small. 6 and 7 show a third embodiment. The same parts as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

In this embodiment, as a means for preventing the controllability of the movable body 20 from deteriorating due to the influence of gravity acting on the movable body 20 of the linear motion gas bearing 14, torque is used instead of the voice coil motor 15. This is different from the first embodiment in that a combination of a rotary motor 40 and a swinging member 41 that keeps constant is adopted. That is, in this case, the pulley 43 is rotatably supported by the arm member 42 projecting above the column 12 so as to project to a position directly above the movable body 20 of the linear motion gas bearing 14, and the rear surface of the column 12 is supported. Place the rotary motor 40 on the mount 44 attached to
A take-up pulley 45 is integrally rotatably attached to the output shaft of the rotary motor 40, and a wire rope 41 as an oscillating member wound around the take-up pulley 45 is connected to the movable body 20 via a pulley 43.

The rotary motor 40 may be of any type as long as its output torque can be easily controlled. In this embodiment, for example, a reduction gear characterized by high torque and high positioning accuracy. Unnecessary direct drive (DD)
Variable reluctance type (VR
(Type) Step motor is used. The rotary motor 40 pulls the movable body 20 upward by a pulling force having the same magnitude as the gravity acting on the movable body 20 and opposite directions, and in synchronization with the movement of the movable body 20 while maintaining balance, the wire rope 4
Take up and rewind 1.

The magnitude of the pulling force is determined by the following equation according to the output torque of the motor and the radius of the winding pulley 45. Pulling force [kg] = Output torque [kg · cm] × Pulley radius [cm] Fine adjustment of the pulling force can be easily performed by changing the output torque by changing the current value of the rotary motor 40. . It is also possible to adjust the pulling force by changing the diameter of the winding pulley 45, if necessary.

In the third embodiment, by using the DD motor having a higher output than the voice coil motor,
There is an advantage that it can be applied even when a large external force acts on the movable body 20. Thus, according to the drive device for a linear motion gas bearing of the third embodiment, even if the external force acting on the movable body 20 changes, the fine adjustment of the balance can be performed easily and with high accuracy by electrical adjustment. In addition, since the movable body 20 is supported by levitation in a substantially weightless state without using a counterweight, the weight of the apparatus can be reduced more than before.

In each of the above embodiments, the movable body 2
When 0 moves vertically up and down, in other words, the movable body 20
The case where the external force acting on the movable body is caused by gravity has been described. However, according to the present invention, some external force other than gravity is applied to the movable body 20.
It can also be applied to the case where it changes when it is stationary or in motion, and it is possible to easily maintain the balance by means of adjusting the balance of the voice coil motor, air cylinder, rotary motor, etc. according to changes in external force. Is.

Further, in each of the embodiments, the feed screw device 13 is used as the linear driving means of the movable body 20, but the invention is not limited to this, and other linear driving devices such as a linear motor can be used. Further, the linear motion bearing may be a linear motion rolling bearing or a linear motion sliding bearing.

[0030]

As described above, according to the drive device for a direct acting gas bearing according to the present invention, even if the weight of the movable body or some other external force changes during movement and at rest, the change can be accommodated. By adjusting the output of the voice coil motor or air cylinder or rotary motor to apply an appropriate balance load, it is possible to easily absorb the change in the weight or external force of the movable body and maintain the balance. The controllability of the drive device for the movable body is improved, and the motion accuracy such as positioning accuracy and speed accuracy is improved.

Further, even if the weight of the mounted object mounted on the movable body is large, the weight of the apparatus can be reduced because the adjustment can be performed without changing the overall weight of the apparatus. In addition to the effects of the above invention, according to the invention of claim 1, since the voice coil motor is used, its output (balance force) can be taken out in a non-contact manner to apply a balance load to the movable body. Thus, there is an effect that the torque fluctuation during the stroke is extremely reduced and the speed accuracy is significantly improved. According to the invention of claim 2, since an inexpensive air cylinder is used, there is an effect that a balance force can be obtained at low cost. According to the third aspect of the invention, since the rotary motor is used, a large balance force can be taken out, and there is an effect that it can be easily applied to a large apparatus.

[Brief description of the drawings]

FIG. 1 is a front view of a first embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view of a second embodiment of the present invention.

FIG. 4 is a plan view of FIG. 3;

5 is a schematic cross-sectional view of a rodless air cylinder used in the one shown in FIG.

FIG. 6 is a front view of the third embodiment of the present invention.

FIG. 7 is a side view of FIG. 6;

FIG. 8 is a front view of a conventional drive device for a linear motion gas bearing.

FIG. 9 is a side view of FIG.

[Explanation of symbols]

 13 Linear drive device 14 Direct acting gas bearing 15 Voice coil motor 19 Fixed body 20 Movable body 30 Air cylinder 40 Rotary motor 41 Swing member (wire rope)

Claims (3)

[Claims] 1. A drive device for a linear motion bearing in which a linear motion bearing for linearly moving a movable body guided by a fixed body and a linear drive device for the movable body are provided side by side in one direction added to the movable body. A drive device for a linear motion bearing, comprising: a voice coil motor that generates a thrust in a reverse direction that balances with an external force and transmits the thrust to the movable body. 2. A drive device for a linear motion bearing in which a linear motion bearing for linearly moving a movable body guided by a fixed body and a linear drive device for the movable body are provided side by side in one direction added to the movable body. A drive device for a linear motion bearing, comprising: an air cylinder that generates a thrust in the opposite direction balanced with an external force and transmits the thrust to the movable body. 3. A drive device for a linear motion bearing in which a linear motion bearing for linearly moving a movable body guided by a fixed body and a linear drive device for the movable body are provided side by side in one direction added to the movable body. A drive device for a linear motion bearing, comprising: a rotary motor that generates a torque in the opposite direction that balances with an external force and transmits the torque to the movable body via a swing member.