JPS63144929A - Double driving mechanism permitting fine and rough movement in precision machine tool - Google Patents

Abstract

PURPOSE:To permit the drive which has a high resolving power for positioning and a high speed responsiveness by combining a finely movable mechanism which supplies a fluid pressure into a hollow structure body and utilizes an elongation quantity due to the deformation of the hollow structure body, with a roughly movable mechanism consisting of a servomotor and a ball screw. CONSTITUTION:The drive which possesses a large stroke and high resolving power as a whole and high responsiveness is permitted by using a roughly movable part consisting of the combination a servomotor 1 or 2 for a large stroke shift and a ball screw 3 or 4 and a finely movable part A for the drive which possesses a small stroke and a high speed high resolving power. In common, a ball screw driving mechanism has a control-disable region because of the frictional torque, etc. In this case, the shift span of the finely movable part is set, and when the position of an object is set into this region, control is suspended, and fine correction drive to an aimed value is carried out by the finely movable part. in this system, the high speed drive which has a large stroke and high resolving power is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drive mechanism for a precision processing machine such as a surface grinder for the purpose of ultra-precision processing on the order of submicrons.

(Prior Art) FIG. 5 shows a typical configuration of a drive system of a conventional surface grinder. 1 is a servo motor connected to a vertical ball screw 3. 2 is also a servo motor and is connected to a horizontal ball screw 4. A main shaft motor 5 drives a grindstone 7 supported by a main shaft bearing 6.

8 is the work. The grinding wheel 7 is driven in the vertical direction (Z-axis) by a drive system consisting of servo motors 1 and 2 and ball screws 3 and 4.
, driven in the left-right direction (Y-axis).

Generally, in such a drive system, the larger the machine, the more
2) The entire grinding wheel is driven by a servo motor, resulting in low responsiveness; 3) The straightness of the grinding wheel during movement is entirely influenced by the accuracy of the guide surface. Therefore, there are problems in that it requires high-precision machining and also leads to an increase in the size of the entire machine, which is extremely disadvantageous in terms of cost.

(Problems to be Solved by the Invention) The present invention attempts to solve the above-mentioned problems of the prior art and to provide a drive mechanism for a precision processing machine that has high positioning resolution and high-speed response.

(Solution by the Invention) The hollow structure is made up of a hollow structure sandwiched between the structures of a processing machine equipped with upper and lower parallel flanges, and a pressure fluid sealed inside the hollow structure. It is characterized by a combination of a fine movement mechanism that utilizes the amount of axial elongation caused by deformation in the axial direction and in a direction perpendicular to the axis, and a coarse movement mechanism that includes a motor and a ball screw.

(Example) FIG. 1 shows a grinding machine equipped with a drive mechanism according to the present invention.

The drive mechanism of the present invention combines a conventional ball screw drive mechanism and a fine movement drive mechanism that utilizes mechanical expansion caused by fluid pressure.

What makes the blade unique compared to Figures 1 and 5 is that a fine movement mechanism A is used between the vertical movement drive body 9 and the main shaft bearing 6.6 In the example of Figure 1, this fine movement Three mechanisms A are used. Coarse movement in the vertical and horizontal directions is performed by driving in the Y-axis and Z-axis directions using a conventional servo motor and ball screw.

Since the three fine movement mechanisms A are arranged so that each one is located at the vertex of a triangle in plan view, it is possible to realize rotational fine movement around the χ axis and linear fine movement in the Z axis direction.

With reference to FIG. 2, the fine movement mechanism A will be briefly explained (
This fine movement mechanism was developed by the same applicant in 1932.
A patent application was filed on November 13, 2013). In FIG. 2, 15 and 15' are machine tool structures, and the fine movement mechanism A is sandwiched within these structures.

The fine movement mechanism A includes a hollow structure 10 made of a cylindrical body with a bottom, a sealing lid 11 of the hollow structure 10, and a pressure fluid source 14 that sends pressure fluid 13 into the hollow structure 10 via a servo valve 12. It consists of

The hollow structure 10 has vertically parallel flanges 10a, 10.
b, and these flanges form the machine tool structure 15°15
' is held in contact with.

By controlling and supplying the pressure of the pressure fluid 13 to the space made liquid-tight by the hollow structure 10 and the sealing lid 11 by the servo valve 12, the hollow structure 1° is heated as shown in FIGS. 3a) and b). As shown in FIG. 2, an elongation δ□ in the direction of the bottom surface and a contraction δ2 in the direction of the bottom surface due to the elongation of the side surfaces occur. δ1 and δ2 are proportional to the warp pressure P in a region where the amount of expansion or contraction is minute. Therefore, the total elongation δ is δ=δ1-δ, =K
It is expressed as P (K; constant of proportionality).

Depending on how it is arranged, the fine drive mechanism A can have a degree of freedom as shown in FIG. 4 or 5. That is, the fourth
In the figure, when the minute drive mechanism A is used alone, in FIG. , rotational fine movements around the χ and χ axes, and linear fine movements in the Y- and Z-axis directions are possible.

The above explanation describes the dual drive mechanism of a grinding machine, but it can be applied to general industrial machinery that requires high-resolution positioning, such as machine tools such as ultra-precision grinders and lathes, and semiconductor manufacturing equipment such as steppers. be.

(Function) Now, the operation of the dual drive mechanism shown in FIG. 1 will be explained. The dual drive mechanism consists of a coarse movement section consisting of a servo motor 1 and a ball screw 3 or a servo motor 2 and a ball screw 3 that can move over a large stroke, and a fine movement section that consists of a fine movement mechanism A that has a small stroke but is capable of high-speed, high-resolution driving. When used in combination with the above section, the overall drive has a large stroke and high resolution, and can be driven with high responsiveness.

In general, a ball screw drive mechanism has a limited positioning resolution due to the presence of friction torque or backlash, and there is a so-called uncontrollable range. Figure 6 shows an example of the response of such a system. In the uncontrollable region, the stopping position is determined by the characteristics of friction torque, backlash, etc. at that time, but these can generally be predicted accurately. That is a problem. Therefore, the movement span of the fine movement section is set as shown in Figure 6, and when the target position falls within this range, the control is stopped and the fine movement section performs a minute correction drive up to the target value. . By using such a method, it is possible to drive the entire device with a large stroke and high resolution, and since the fine movement section drives only the tip, the load is small and high-speed drive is possible.

Note that the fine movement mechanism can have up to six degrees of freedom depending on the arrangement of each actuator.

(Effects) Fluid pressure is supplied into the hollow structure outside the coarse mover end using a servo motor and a ball screw, and a fine movement mechanism that utilizes the amount of elongation caused by the deformation of the hollow structure is combined, so it is different from the conventional servo motor. There is no backlash or backlash that is unavoidable in high-precision positioning mechanisms using ball screws, and it is now possible to obtain an extremely precise fine movement mechanism.

[Brief explanation of the drawing]

FIG. 1 shows a surface grinder equipped with a two-structure drive mechanism according to the present invention. Figure 2 is a conceptual diagram of the fine movement mechanism. FIG. 3 is a diagram explaining the principle of the fine movement mechanism. Figure 4 shows a surface grinder using a single fine movement mechanism. FIG. 5 similarly shows a surface grinding machine that uses a plurality of fine movement mechanisms to have degrees of freedom in a plurality of directions. FIG. 6 is a diagram showing an example of a coarse movement part response and a response at the time of minute correction. Figure 7 shows a conventional surface grinder. In the figure; A Fine movement mechanism 1, 2 Servo motor 3.4
Ball screw 5 Main shaft motor 6 Main shaft bearing part
7 Grindstone 8 Work 9 Vertical shaft main body 10 Hollow structure 10a, 10b Flange 11 Sealing lid body 12 Servo valve 13 Pressure fluid
14 Pressure fluid source 15 Machine tool structure 16
Vertical plane 17 Horizontal plane or more Applicant Sumitomo Heavy Industries, Ltd. Sub-Agent Patent Attorney Ohashi Younger brother 1 Figure $ 2 Figure 3 (.) (b) Figure 40 (, Figure 5 Figure 6

Claims (1)

[Claims] It consists of a hollow structure sandwiched between the structures of a processing machine equipped with upper and lower parallel flanges, and a pressurized fluid sealed inside the hollow structure. By changing the fluid pressure, the axial direction of the hollow structure A fine movement mechanism that utilizes axial elongation caused by deformation in orthogonal directions, and a coarse movement mechanism that includes a motor and a ball screw. Heavy drive mechanism.