JPS60263634A - Highly accurate machine tool - Google Patents

Abstract

PURPOSE:To improve the guiding accuracy of ram, in a ram guide structure of machine tool for fragile material such as silicon, by constructing such that the projections formed on the ram are guided in vertical direction through a roll bearing and a slide bearing. CONSTITUTION:Projections 82 having narrow span W are formed longitudinally over the entire length of ram 80 where a parallel guide faces 82A of fine finish are formed on the front and rear wallfaces while a face crossing perpendicularly with the guide face 82A is formed on the sliding guide face 82B of fine finish. The parallel guide face 82A is contacted against a pair of roll bearings 63 separated by predetermined span L. Here, the ratio L/W between the span L in the direction of Y-axis and the span W between the parallel guide faces 82A of the roll bearing 63 is made higher than 3. The sliding guide face 82B will contact respectively against a pair of sliding guide bearing 65 to constitute a vertical guide. With such structure, the guide accuracy of ram can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to slicers that cut workpieces made of brittle materials such as silicon and ferrite with ultra-precision, small-sized carving machines, precision surface grinders, etc. The present invention relates to high-precision machine tools, and particularly to improvements in the guide structure of a ram having a spindle head.

[Background Art and Problems] Conventionally, in high-precision machine tools such as those mentioned above, when a ram having a spindle head is of a movable type, the guide structure of the ram is a hydrostatic guide or a hydrodynamic guide. This is common. This is because aerostatic pressure guides cannot support the ram in the sagging direction due to the rigidity of the guide surface, and simple rolling bearings are not necessarily accurate enough due to problems with vibration damping. This is because he was being treated.

However, in the case of hydrostatic guides, it is troublesome to process sleeve circulation, and heat is generated due to oil supply and ram drive, and this heat causes partial thermal deformation, resulting in high There is a problem that accuracy cannot be maintained. on the other hand,
If only hydrostatic pressure is used, very high-precision machining is required, and since the ram is long, this machining cost is high, which is disadvantageous in terms of manufacturing costs. Since the shaft is guided by the shaft, a gap is likely to be formed on the guide surface, and the existence of this gap causes the ram and eventually the spindle of the main shaft head to tilt, making it impossible to maintain high precision.

Therefore, there is a need for a ram guide structure that does not require high production costs and can maintain high accuracy.

[Object of the Invention] An object of the present invention is to provide a guide structure that can guide a ram with high precision in a ram-driven high-precision machine tool and that does not require very high manufacturing costs.

EMeans and effects for solving the problems The present invention has the following features:
Protrusions extending in the movement direction are formed on opposing surfaces along the movement direction of the ram, and parallel guide surfaces forming the outer shape of each protrusion are received by rolling bearings to eliminate gaps on the bearing surfaces, In addition, a suitable surface of the ram different from the parallel guide surface of this protrusion is supported by a sliding bearing so that vibrations that are difficult to damp with a rolling bearing are damped by a sliding bearing, which results in a significant increase in costs. The purpose is to achieve the above objective by enabling highly accurate guidance.

[Example] Hereinafter, an example in which the present invention is applied to a slicer that performs ultra-precision cutting or grooving of brittle materials will be described with reference to the drawings.

In FIG. 1, which schematically shows the overall configuration, a saddle 30 is placed on a bed 10 having an integral cylindrical structure so as to be movable in a predetermined direction in a horizontal plane, that is, in the Y-axis direction. Said bed 1
0, two V grooves 11 are formed in a precise straight line in the Y-axis direction at a predetermined distance apart, and a saddle 30 is formed in the middle of these two V-grooves 11 in the Y-axis direction. A groove 12 for arranging the feed screw shaft is also formed in the Y-axis direction. In addition, two V-shaped protrusions 31 that engage with the two V-grooves 11 are integrally formed on the lower surface of the saddle 30, and each of these two V-shaped protrusions 31 By engaging the V groove 11, the saddle 3
0 is designed to be guided with high precision in the Y-axis direction.

At this time, oil is interposed between the contact surfaces of the V-groove 11 and the protrusion 31, forming an oil dynamic pressure bearing 13.

A guideway 32 having a substantially T-shaped cross section perpendicular to the longitudinal direction is attached to the upper surface of the saddle 30, and a table 50 on which a workpiece such as a silicon billet can be placed and fixed is attached to the guideway 32. is supported so as to be movable in a predetermined direction in a horizontal plane and perpendicular to the moving direction of the saddle 30, that is, in the X-axis direction. Further, the horizontal projecting portions 32A on both edges of the upper end of the T-shape of the guideway 32 are precisely finished, and the portions that engage with the upper and lower surfaces and side surfaces of both horizontal projecting portions 32A of the table 50 are provided with air (not shown). Bearing air supply pads are provided, and an opposing air static pressure guide 33 is formed at the engagement portion between these horizontal extensions 32A and the air supply pads.

A column 60 is erected and fixed on the rear upper surface of the bed IO, and a ram 80 having a spindle head 70 on the top is mounted on the column 60 in the direction of movement of the saddle 30 and table 50, that is, in the X and Y axis directions. Both are supported so as to be movable in the vertical direction (Y-axis direction) orthogonal to each other. The spindle head 70 includes a grindstone flange mounting spindle 71 having a tapered tip, and this spindle 71 is supported by an ultra-precision cylindrical aerostatic bearing. In addition, the spindle head 70 has a built-in forced cooling type AC induction transmission equipped with a cooling jacket, which has low heat generation, low vibration, and high precision rotation. It is possible to select the rotation speed steplessly.

In the longitudinal cross-sectional view of FIG. 2, an ultra-precision pole screw shaft 21 is disposed within the groove 12 of the bed 10, and both ends of this pole screw shaft 21 are supported by left and right pole bearings 14 attached to the bed 10. , is rotatably supported with a double-sided structure. One end of this pole screw shaft 21 is connected to the output shaft of a DC servo motor 23 via a coupling 22, and a pair of preloaded pole nuts 24 are screwed into the threaded portion. The pair of pole nuts 24 are fixed to the lower surface of the saddle 30 via a bracket 25. As a result, when the screw shaft 21 is rotated by the motor 23, the pole napft 24 and, in turn, the saddle 30 are moved to Z as the screw shaft 21 rotates.
It is designed to move forward and backward in the axial direction.

In the partially cutaway front view of FIG. 3 and the plan view of FIG. −
Necessary oil is supplied from 15 to the hydraulic pressure bearing 13 formed by the V groove 11 and the V-shaped protrusion 31 of the saddle 30. Further, at one end of the bed 10 and the saddle 30 located away from the pole screw shaft 21, there is a measuring instrument that can measure the amount of movement of the saddle 30 relative to the bed 10 with high precision, for example, to 0.1 gm using a linear scale or the like. Means 27 is provided, and the measurement signal from this measuring means 27 is fed back to the DC servo motor 23, so that the movement of the saddle 30 can be controlled with high precision.

A DC servo motor 41 is attached to one end of the saddle 30, the upper surface of the left end in FIG. 3, via a bracket 34.
The rotation of this motor 41 is controlled by a pulse coder 42 attached to the rear end of the motor 41. Further, one end of a feed screw shaft 43 made of a triangular screw is connected to the output shaft of the motor 41.
One end is supported by a bearing (not shown) in the bracket 34, and the other end is supported by a bearing 35 installed in a groove 32B at the center of the guideway 32, so that it is supported on both sides. Furthermore, a non-circulating rolling roller screw unit 44 incorporating a plurality of fine-pitch roller screws that eliminate backlash is screwed into the threaded portion of the feed screw shaft 43 . and is fixed to the lower surface of the table 50.

In FIG. 2, the ram 80 is formed into a hollow box shape, and a long hole 81 as a notch extends along the longitudinal direction of the ram 80, that is, the Y-axis direction which is the direction of movement of the ram 80. are provided to penetrate the front and rear walls of the ram 80, and the pole screw shaft 21 for the saddle drive is disposed through this elongated hole 81, so that even if the ram 80 moves in the Y-axis direction, the ram 80 remains fixed. 80 and the pole screw shaft 21 do not interfere with each other.

At the rear position of the ram 80, an ultra-precision one-pole screw shaft 91 is rotatably supported vertically on both sides by the column 60 via upper and lower pole bearings 61. The upper end of this pole screw shaft 91 is connected to the output shaft of a DC servo motor 93 via a coupling 92, and a pair of preloaded pole nuts 94 are screwed into the threaded portion of the shaft. This pair of Paul Naftoku 4
is fixed to the rear surface of the ram 80 via a bracket 95. As a result, when the screw shaft 91 is rotated by the motor 93, the pole napft 9 is rotated as the screw shaft 91 rotates.
4, and thus the ram 80 is moved forward and backward in the Y-axis direction.

A scale reader 97 is attached to the rear surface of the bracket 95 via a mounting base 96 (see FIG. 5), and a linear scale 98 is arranged corresponding to this scale reader 97. and scale reader 9
7, a measuring means 99 that can read with high precision, for example down to 0.1 μm, is mounted horizontally. With this measuring means 99,
Ram 80 for ball nut 94 and therefore column 60
The amount of movement in the Y-axis direction is read, and the signal of this amount of movement is
The movement of the ram 80 can be controlled with high precision by being fed back to the DC servo motor 93. At this time, the scale 98 is fixed to the back surface of the column 60 via the scale mount 62.

As shown in the enlarged cross-section in FIG. Projections 82 each having a narrow span W are integrally formed. The front and rear walls of these protrusions 82 are precisely finished to form parallel guide surfaces 82A, and the side wall surfaces of the protrusions 82 perpendicular to these parallel guide surfaces 82A are also precisely finished to form sliding guide surfaces 82B. has been done.

Each pair of rolling bearings 63 is in contact with each of the four parallel guide surfaces 82A at a distance of a relatively long predetermined span L in the Y-axis direction. Each pair that comes into contact with 82A is provided at a position facing each other. At this time, the rolling bearing 6
The ratio of the span L in the Y-axis direction to the span W between the parallel guide surfaces 82A in No. 3, that is, the narrow ratio L/W, is set to 3 or more, in fact about 5, to reduce the effects of pitching and yawing accompanying the movement of the ram 8o. This is intended to improve positioning accuracy.

Each of the rolling bearings 63 is attached to a pedestal 64, and one of the pedestals 64, which faces the parallel guide surface 82A, is fixed to the column 60 with bolts. The other pedestal 64 is brought into contact with the inner surface of the column 60 via an inclined surface, and this other pedestal 64
By adjusting the amount of insertion in the Y-axis direction into the column 60 of No. 4, a predetermined preload can be applied between the opposing rolling bearing 63 and the parallel guide surface 82A due to the action of the inclined surface, and, In this state, each pedestal 64 can be fixed to the column 6o. Thereby, the ram 80 can be guided by the rolling bearing 63 without play.

A pair of upper and lower sliding bearings 65 is brought into contact with each sliding guide surface 82B of each of the protrusions 82, facing each other, and the contact surface between these sliding bearings 65 and the inner surface of the column 60 is also in contact with the sliding guide surface 82B of each of the protrusions 82. Like the base 64, it is an inclined surface, and by adjusting the amount of insertion of these sliding bearings 65 into the column 60 in the Y-axis direction, the sliding guide surface of both protrusions 82 is created between both sliding bearings 65 facing each other. 82B is inserted without any gaps, and in this state the sliding bearing 65 can be fixed to the column 60.

In addition, an oil groove is formed on the surface of each slide bearing 65 that comes into contact with the slide guide surface 82B, and oil is supplied to each oil groove, so that the slide bearing 65 and the slide guide surface 82B As a result, a hydraulic pressure sliding surface is formed.

The vicinity of both side edges of the rear surface of the ram 80 are each precisely finished to form sliding guide surfaces 80A, and each of these sliding guide surfaces 80A is provided with a pair of upper and lower sliding bearings 66 that act as auxiliary sliding bearings. The contact surface between these sliding bearings 66 and the inner surface of the column 60 is also in contact with the pedestal 6.
4 and the sliding bearing 65, and by adjusting the amount of insertion of these sliding bearings 66 into the column 60 in the Y-axis direction, each sliding bearing 66 and the sliding guide surface 8
The gap with 0A is eliminated, and in this state, the sliding bearing 6
6 can be fixed to the column 6o.

Note that reference numeral lOO in FIG. 2 is a grindstone flange that supports the grindstone lot and is detachably attached to the spindle 71.

Next, the operation of this embodiment will be explained.

A workpiece such as a silicon billet is fixed on the table 50 using an appropriate jig or the like. At this time, the surface to be processed (cut surface) is made parallel to the moving direction of the table 5o, that is, the X-axis direction.

On the other hand, a grindstone 101 is attached to the spindle 71 of the spindle head 7o via a grindstone flange 100, and machining is started in this state. Saddle 3o at the start of this processing,
The positions of the table 5o and the ram 80, that is, the spindle head 70, are the positions shown by solid lines in FIGS. 2 and 3, in other words, the saddle 30 is located at the very front of the device, on the left end side in FIG.
The table 50 is at the right end in FIG. 3, and the ram 80 is at the uppermost position.

For machining, first we will use the DC servo motor 2 for driving the saddle.
3 to position the saddle 30 via the ball screw shaft 21, pole nut 24, etc. This position is determined while being checked by the measuring means 27 provided between the saddle 30 and the head 10.

Next, while driving the DC servo motor 93 for driving the ram, the amount of cut into the workpiece by the spindle head 70, that is, the grinding wheel 1O1 is given while feedback control is performed by a measuring means 99 consisting of a scale reader 97 and a scale 98. The ram 80 is lowered to the desired position or, in the case of cutting, to a position sufficient for cutting. In this state, the DC servo motor 41 for driving the table is driven, and while being controlled by the pulse coder 42, the workpiece is transferred together with the table 50 in the X-axis direction to perform predetermined processing.

After machining is completed, the table 50 is returned to the initial position, the saddle 30 is advanced to the next machining position, and the table 50 is returned to the initial position.
Move 0 and perform the next machining. At this time, if the grinding wheel 101 is worn due to machining and the cutting position changes, and the amount of wear is known in advance, the ram drive motor 93 may be lowered sequentially according to the amount of wear using the program. good.

These series of operations are performed automatically and continuously by a computer or manually and sequentially, and by repeating this, the workpiece is sequentially processed.

According to this embodiment as described above, there are the following effects.

That is, since the saddle 30 is guided by the hydraulic pressure bearing 13 through the double V-groove 11, it is not affected by yawing or the like that accompanies movement to the saddle 30, and therefore, it is easy to assemble and adjust each part. For maintenance and inspection purposes, the measuring means 27, which is installed at a distance from the pole screw shaft 21, is hardly affected by the errors in the roughness that would occur in a conventional structure, and allows for high-precision feeding. In turn, processing can be performed. Further, since the saddle 30 is guided by hydrodynamic pressure, unlike hydrostatic pressure, there is no heat generation, and there is no thermal deformation due to heat generation, so high-precision machining can be realized from this point as well.

Also, a table 5 which is in charge of feeding the workpiece in the cutting direction
0 does not require high precision for the saddle 30 and ram 80, so the guide is a static pressure air bearing 33, and the feed control is performed by a pulse coder 42, so that it can be manufactured at low cost. In addition, since the reroller screw unit 44 with non-circulating rollers is used to convert the rotation of the feed screw shaft 43 into linear motion of the table 50, smooth feeding can be performed without circulating vibrations. Highly accurate guidance can be achieved. In addition, by adopting the opposed aerostatic pressure bearing 33, there is no stick-slip at low speeds and no heat generation, so that high-precision guidance can be performed from this point of view as well, and accuracy will not be impaired over a long period of time.

Furthermore, since the ram 80 that is moved in the vertical direction is guided by a rolling bearing 63 that is given a preload, the ram 80
It can sufficiently support the overturning moment of the robot, and also provides high-precision guidance. At this time, the narrow ratio L of the rolling bearing 63
/W is made very large, so it is less susceptible to pitching and yawing caused by the drive of the ram 80.
High accuracy can also be maintained from this point of view. In addition to the rolling guide mentioned above, the ram 80 is guided by sliding bearings 65 and 66 on the left, right and rear surfaces, so vibrations that are difficult to damp with rolling guides are damped by these sliding bearings 65 and 65. From this point of view as well, highly accurate guidance can be achieved.

Furthermore, since the ram 80 is of a movable type, the height of the entire apparatus can be made lower than that of a double column type in which the spindle head is driven. In addition, in order to improve accessibility to the front of the device, the saddle drive motor 23 is placed at the rear of the device, so there is a possibility that the ram 80 and the pole screw shaft 21 will interfere with each other. Since the pole screw shaft 21 is inserted through the shaft 81 to avoid interference, the height can also be lowered and stability can be improved. In addition, the screw shaft 21
, 43.91 are provided at the center of each arrangement part, and the entire device is formed as symmetrically as possible.
There is little local deformation due to temperature changes, etc., and accuracy can be maintained from this point of view as well.

Further, the motors 23, 41, 93 as heat generating sources are exposed to the outside as much as possible, and the spindle head 70, which cannot be exposed, is
Since the motor can be forcedly cooled, it will not be deformed due to heat generation.

In the above embodiments, the present invention was explained as an example in which the present invention was applied to a slicer, but the present invention is not limited to this, and can also be applied to other high-precision machine tools such as a die-sinking machine, a precision surface grinder, etc. Applicable. Further, the elongated hole 81 as a notch provided in the ram 80 may be a long groove with an open bottom, but it is advantageous to make the elongated hole 81 not open at the bottom because the rigidity can be increased.

[Effects of the Invention] According to the present invention as described above, the ram can be guided with high precision without a significant increase in cost.

[Brief explanation of the drawing]

The figures show an embodiment in which the present invention is applied to a slicer, in which Fig. 1 is a schematic perspective view thereof, Fig. 2 is a vertical sectional view showing the detailed structure, Fig. 3 is a partially cutaway front view, FIG. 4 is a plan view, and FIG. 5 is an enlarged sectional view taken along line V--■ in FIG. 2. lO...Bed, 11...V groove, 13...Hydraulic pressure bearing, 21...Pole screw shaft, 24...Pole nut, 30...Saddle, 31...V-shaped protrusion Department, 33・
・・Opposing air static pressure guide, 43 ・・Feed screw shaft, 50・
...Table, 60...Column, 63...Rolling bearing, 65゜66...Sliding bearing, 70...Spindle head, 80...Ram, 81...Long hole as notch , 82... Projection, 82A... Parallel guide surface, 82B...
...Sliding guide surface, 91...Pole screw shaft. Figure 4 Figure 5

Claims (1)

[Claims] (1) A ram having a spindle head is supported vertically movably on a column fixed to a bed, and the ram is extended in the direction of movement on opposing surfaces along the direction of movement. The ram and column are guided in the vertical direction via rolling bearings on parallel guide surfaces that form the outer shape of each ridge of the ram, and are guided in the vertical direction via rolling bearings at a different position from the parallel guide surfaces. A high-precision machine tool that is guided vertically via sliding bearings. (2. In claim 1, the rolling bearing is provided on the column at a predetermined distance in the vertical direction, and the sliding bearing is perpendicular to the parallel guide surface and extends in the vertical direction. A high-precision machine tool characterized by being formed between a sliding guide surface provided on a ram and a column. (3) In claim 2, the ram and column refer to the parallel guide surface. A high-precision machine tool characterized in that it is further guided by an auxiliary sliding bearing provided in parallel with the rolling bearing. (4) In claim 2 or 3, the vertical span L of the rolling bearing is A high-precision machine tool characterized in that the ratio L/W of the span W of the parallel guide surface and the span W of the parallel guide surface is 3 or more.