JP2005279793A - Pre-load support and ultraprecise working method of thin member using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pre-load support and an ultraprecise working method of a thin member using it, hardly causing deformation and internal stress in a thin workpiece, firmly supporting the workpiece, and reducing or preventing influence of gravity and working external force. <P>SOLUTION: This pre-load support includes: a cylindrical piston 12; a cylindrical piston rod 14 concentrically connected to the piston and extended in the axial direction; and a cylinder 16 guiding the piston and the piston rod to move in the axial direction. The cylinder has a cylindrical gas chamber 16a storing the piston to be axially moved by pressure of gas supplied to the interior, and a hollow cylindrical oil chamber 16b surrounding the piston rod and supplied with oil pressure. The inner wall 17a of the oil chamber forms a very small gap communicated with the gas chamber in a space up to the piston rod when the oil pressure is lower than a predetermined low pressure, and when the oil pressure is higher than a predetermined high pressure, the inner wall holds the piston rod and fixes the same to maximize its sliding resistance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a preload support for reducing deformation of a workpiece during machining and enabling ultraprecision machining, and an ultraprecision machining method for a thin member using the same.

  [Non-Patent Document 1] discloses a polishing process of a large concave mirror (primary mirror) used in a Subaru telescope. This large concave mirror is made of ultra-low expansion glass having a diameter of 8.3 m, a thickness of 200 mm, and a weight of 24 tons. This large concave mirror is first shaped into a hexagonal flat plate with a diameter of 1.5 m, and a large number (44 pieces) are arranged and fused to form a large-diameter disc, which is deformed along a spherical block. To form a spherical disk. Next, the concave surface is placed on the turntable, supported by a number of hydraulic support pads, and the concave surface is polished with a lap while rotating the turntable.

On the other hand, [Patent Document 1] has been proposed as an apparatus for fixing a support rod of a work support for a machine tool at a predetermined height position in the same manner as the hydraulic support pad.
As shown in FIG. 12, the “collet clamp” of Patent Document 1 has an annular collet 60 fitted on a support rod 54 inserted into a housing 52, and an annular taper gap C is formed in the collet. A tool 64 is arranged. A large number of balls B are inserted into the annular taper gap C in a state of being arranged in the circumferential direction and the vertical direction, and these balls B are pushed up by a pressing spring 67.
When pressure oil is supplied to the hydraulic working chamber 65 at the time of clamping, the clamping piston 74 moves the transmission tool 64 downward against the return spring 78, and the tapered inner peripheral surface of the transmission tool 64 rolls the ball B. The collet 60 is engaged with the outer peripheral surface of the collet 60 while the collet 60 is contracted, whereby the diameter of the collet 60 is reduced and the support rod 54 is clamped and fixed at a predetermined height position.

Masatsugu Otsubo, “Subaru Telescope Optical System, 8m Main Mirror Production, Polishing Process”, Optical Technology Contact, Vol. 36, no. 1 (1998)

Japanese Patent Laid-Open No. 10-146733, “Collet Clamp”

  For example, when used in outer space, even a large concave mirror is hardly affected by gravity, so the thickness can be made very thin and a significant weight reduction can be achieved. For example, even if the diameter is 8.3 m, which is the same as that of the Subaru Telescope, if the thickness can be made 5 mm, for example, the weight can be reduced to about 1/40 or about 500 kg.

However, when such a thin member is precisely processed on the ground, there are the following problems.
(1) When machining a thin and precise product, the material itself needs to have high rigidity, high thermal conductivity, and low thermal expansion. However, a material having such characteristics is, for example, SiC, which is very hard and difficult to process.
(2) An ELID (Electrolytic In-process Dressing) grinding method is known as a processing means capable of mirror processing even with a hard material such as SiC. This ELID grinding method is a method in which a conductive grindstone is ground while being electrolytically dressed, and has a feature that the machining resistance is small and mirror finishing can be performed with high efficiency. However, some resistance (for example, about 2 to 5 kg) is generated even by the ELID grinding method. Therefore, since the thin member is deformed by this processing resistance, precise processing becomes difficult.

(3) By using the “hydraulic support pad” of Non-Patent Document 1 and the “Collet Clamp” of Patent Document 1 to contact the back of the processed part of the thin member and support it, In principle, it is possible to reduce the deformation and to enable precision machining.
However, such a hydraulic support pad and collet type clamp have a large pressing force when abutting against the back surface of the processed part, and this pressing force causes a deformation and internal stress that cannot be ignored in the thin-walled part.

For example, in the hydraulic support pad and collet clamp described above, the sliding resistance is large due to the resistance of the dustproof seal, etc., and the minimum pressing force is about 400 g, which is a minimal force that does not cause deformation or internal stress in the processed product. It is difficult to support.
Further, if the spring is used to support and use a force that overcomes the sliding resistance, when the product is fixed, the piston instantaneously moves when it exceeds the static resistance with the cylinder, so that the product is deformed. In thin-walled products and ultra-precision machining, this deformation and internal stress are a major problem.
Further, in the method of controlling the support force by the spring force, the force changes according to the stroke.
In principle, it is possible to fix the support member in contact with the opposite surface with a minute force that does not cause deformation or internal stress by relying on manual work. However, with this method, the amount of deformation is measured using a dial gauge, etc., and adjustment is performed using a screw or the like. This requires not only a long time but also requires skill, and is not reproducible or reliable. was there.
Further, in the conventional precision processing method, when a thin member is processed on the ground, the thin member is processed in a state where gravity (self-weight) is applied thereto, so that there is a problem that deformation due to gravity cannot be avoided.

  The present invention has been developed to solve such problems. That is, the first object of the present invention is to contact the workpiece with a minute force (for example, less than about 400 g) that hardly generates deformation or internal stress even if the workpiece is a thin member. In addition, it is possible to firmly support the workpiece against a sufficiently large machining resistance (for example, about 20 kg or more) at that position, thereby preloading which can greatly reduce the deformation of the workpiece during machining. The object is to provide a support and a method for ultra-precision machining of a thin member using the same. The second object of the present invention is to provide an ultra-precise machining method for thin-walled members that can reduce or avoid the influence of gravity (self-weight) acting on the thin-walled portion and external working force when machining a workpiece on the ground. Is to provide.

According to the present invention, it comprises a cylindrical piston, a cylindrical piston rod concentrically connected to the piston and extending in the axial direction, and a cylinder for guiding the piston and the piston rod so as to be movable in the axial direction.
The cylinder includes a cylindrical gas chamber that accommodates a piston movably in the axial direction with the pressure of a gas supplied to the inside, and a hollow cylindrical oil chamber that surrounds the piston rod and is supplied with hydraulic pressure. Have
When the oil pressure is lower than a predetermined low pressure, the inner wall of the oil chamber forms a minute gap communicating with the gas chamber between the piston rod and the gas passing through the minute gap from the gas chamber. Is configured to minimize the sliding resistance of
When the hydraulic pressure is higher than a predetermined high pressure, the inner wall is swelled inward by elastic deformation to grip and fix the piston rod, and the sliding resistance is maximized. Preload support is provided.

According to the above configuration of the present invention, when the oil pressure is lower than a predetermined low pressure, the inner wall of the oil chamber forms a minute gap communicating with the gas chamber between the piston rod and the gas passes through the minute gap. The piston rod sliding resistance is minimized, so even if the work piece is a thin member, the work piece can be processed with a very small force (eg, less than about 400 g) that hardly generates deformation or internal stress. It can be made to contact.
Further, the inner wall of the oil chamber is configured so that when the hydraulic pressure is higher than a predetermined high pressure, the inner wall swells inward by elastic deformation, grips and fixes the piston rod, and maximizes its sliding resistance. Therefore, it is possible to firmly support the workpiece against a sufficiently large processing resistance (for example, about 20 kg or more) at a position where it is in contact with the workpiece, thereby deforming the workpiece during machining. Can be greatly reduced.

According to a preferred embodiment of the present invention, an air source capable of supplying air containing oil mist to the gas chamber, and a pressure control valve capable of finely adjusting the pressure of the air,
The pressure of the air is set to an extremely low pressure at which the piston and the piston rod move toward the workpiece and abuts against the workpiece with a minute force that hardly generates deformation or internal stress.

With this configuration, it is possible to increase the sealing effect by the surface tension of the oil mist and to minimize the sliding resistance with the air containing the oil mist.
Further, by setting the air pressure to an extremely low pressure, the pressing force against the workpiece can be controlled to a minute force that hardly generates deformation or internal stress.

  A hydraulic pressure source capable of supplying a hydraulic pressure of a predetermined pressure to the oil chamber; and a non-leak valve capable of sealing the hydraulic pressure so as not to leak.

  With this configuration, the oil pressure is supplied to the oil chamber, the piston rod is gripped, and the sliding resistance is maximized so that the hydraulic pressure can be sealed with a non-leak valve so that there is no leakage. It can be removed and the workpiece can be moved freely.

Further, according to the present invention, a contact step of contacting a cylindrical piston rod having an end surface supporting the processed part back surface of the workpiece,
A fixing step of gripping and fixing the piston rod in a state where the end surface is in contact with the processing portion rear surface of the workpiece;
And a processing step of processing a processed portion of the workpiece while the piston rod is fixed in the fixing step.

  According to this method, the piston rod is brought into contact with the back surface of the processed part of the workpiece in the contact step, and in this state, the piston rod is gripped and fixed in the fixing step. In this state, the workpiece is processed in the processing step. Therefore, even if the work piece is a thin-walled member, the work piece can be firmly supported against a sufficiently large working resistance (for example, about 20 kg or more), thereby deforming the work piece during machining. Can be greatly reduced.

  According to a preferred embodiment of the present invention, in the abutting step, the pressing force of the piston rod is set to a minute force that hardly causes deformation or internal stress in the processed portion of the workpiece.

  By this method, it is possible to firmly support the workpiece against a large processing resistance without causing almost any deformation or internal stress in the processed portion of the workpiece.

  According to another preferred embodiment of the present invention, in the contact step, a simulation is performed in consideration of deformation of the workpiece, the result is fed back, and the pressing force of the piston rod is applied to the weight of the workpiece. Or set the force to compensate for the amount of deformation due to external force.

  According to this method, a simulation is performed in consideration of deformation of the workpiece, and the result is fed back, so that the machining portion of the workpiece can be machined by applying an optimum magnitude of force to compensate for the deformation.

  As described above, the preload support according to the present invention and the ultra-precision machining method for thin-walled members using the same are very small forces (for example, less than 400 g) that hardly cause deformation or internal stress even if the workpiece is a thin-walled member. Can be brought into contact with the workpiece and can firmly support the workpiece against a sufficiently large processing resistance (for example, about 20 kg or more) at the position, thereby allowing the workpiece to be machined during machining. The deformation of the object can be greatly reduced, and when processing the workpiece on the ground, the influence of gravity (self-weight) acting on the thin part and processing external force can be reduced or avoided, etc. Has an excellent effect.

  The present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a cross-sectional view showing a first embodiment of a preload support according to the present invention. In this figure, the preload support 10 of the present invention is for upward use, and includes a cylindrical piston 12, a cylindrical piston rod 14, and a cylinder 16.

  The cylindrical piston rod 14 is concentrically connected to the piston 12 and extends in the axial direction Z. Further, the one end surface 14a of the cylindrical piston 14 is formed in an arbitrary shape (in this example, an arc shape) so as to be in contact with and support the back surface of the processed portion of the workpiece (not shown). In addition, you may attach another contact member (for example, elastic pad) to the end surface 14a with a screw | thread or an adhesive material.

  The cylinder 16 guides the piston 12 and the piston rod 14 so as to be movable in the axial direction Z. The cylinder 16 includes a cylindrical gas chamber 16a and a hollow cylindrical oil chamber 16b.

The cylindrical gas chamber 16a has an inner diameter slightly larger than the diameter of the piston 12, and accommodates the piston 12 so as to be movable in the axial direction (in this example, upward) by the pressure of the gas supplied to the inside.
The hollow cylindrical oil chamber 16b surrounds the piston rod 14 and is supplied with hydraulic pressure.

The inner wall 17a of the oil chamber 16b is thinner than the outer wall 17b, and the gap between the oil chamber 16b and the piston rod 14 varies depending on the magnitude of the supplied hydraulic pressure.
The thickness of the inner wall 17a forms a minute gap (for example, about 5 μm) communicating with the gas chamber between the piston rod 14 when the supplied hydraulic pressure is lower than a predetermined low pressure (for example, about 0.2 MPa). The gas supplied to the gas chamber 16a passes through the minute gap and the sliding resistance of the piston rod 14 is minimized (for example, less than 400 g).
On the other hand, the thickness of the inner wall 17a is such that when the supplied hydraulic pressure is higher than a predetermined high pressure (for example, about 1.0 MPa), the inner wall swells inward by elastic deformation and grips and fixes the piston rod 14, The sliding resistance is maximized (for example, about 20 kg or more).

In FIG. 1, the preload support 10 of the present invention further includes an air source 22, a pressure control valve 23, a hydraulic pressure source 24, and a non-leak valve 25.
The air source 22 supplies air containing oil mist to the gas chamber 16a. The pressure control valve 23 finely adjusts the pressure of air from the air source 22. The pressure control valve 23 causes the air pressure to move the piston 12 and the piston rod 14 toward the work piece, and with a minute force (for example, less than 400 g) that hardly generates deformation or internal stress. Set to a very low pressure that contacts the surface.
The hydraulic pressure source 24 supplies a hydraulic pressure of a predetermined pressure (lower than the low pressure or higher than the high pressure) to the oil chamber 16b. The non-leak valve 25 encloses the hydraulic pressure supplied from the hydraulic source so as not to leak.
The air line and the hydraulic line may be provided with other well-known piping devices (for example, a direction switching valve, a pressure adjustment valve, an on-off valve, a quick joint, etc.).

FIG. 2 is a cross-sectional view showing a second embodiment of the preload support according to the present invention. In this figure, the preload support 10 of the present invention is for downward use and includes a cylindrical piston 12, a cylindrical piston rod 14, and a cylinder 16.
In this example, the cylindrical gas chamber 16a is supplied to the step portion between the piston 12 and the piston rod 14, and adjusts the downward force of the piston 12 by the pressure of the gas supplied inside. Other configurations are the same as those in FIG.

  The structure of the preload support is not limited to the above-described example, and a piston rod may be provided on both sides of the piston so that gas is supplied to both sides of the piston. Further, the moving direction of the piston rod 14 may be horizontal or oblique in addition to downward and upward.

According to the configuration of the present invention described above, when the oil pressure is lower than a predetermined low pressure, the inner wall 17a of the oil chamber forms a minute gap that communicates with the gas chamber between the piston rod 14 and the minute gap is formed into the gas. Is passed through to minimize the sliding resistance of the piston rod, so even if the work piece is a thin member, the deformation and internal stress hardly occur even with a very small force (for example, less than about 400 g). It can be brought into contact with the workpiece.
Further, the inner wall 17a of the oil chamber is configured such that when the hydraulic pressure is higher than a predetermined high pressure, the inner wall swells inward by elastic deformation and grips and fixes the piston rod 14 to maximize its sliding resistance. Therefore, it is possible to firmly support the workpiece against a sufficiently large processing resistance (for example, about 20 kg or more) at a position where the workpiece is brought into contact with the workpiece. Can be greatly reduced.

  Also, with air containing oil mist, the sealing effect can be enhanced by the surface tension of the oil mist, and the sliding resistance can be minimized. Furthermore, by setting the air pressure to an extremely low pressure, the pressing force against the workpiece can be controlled to a minute force that hardly generates deformation or internal stress.

  Further, since the oil pressure of a predetermined pressure is supplied to the oil chamber 16b to grip the piston rod 14, and the sliding resistance is maximized, the non-leak valve 25 can seal the oil pressure so that there is no leakage. And the workpiece can be moved freely.

Next, a method for ultra-precision processing a thin member using the above-described preload support 10 will be described.
FIG. 3 is a flow diagram illustrating the method of the present invention. As shown in this figure, the method of the present invention comprises a contact step S1, a fixing step S2, and a processing step S3.

In the contact step S1, a cylindrical piston rod 14 having an end surface 14a that supports the processed part back surface of the workpiece is contacted.
In the fixing step S2, the piston rod 14 is gripped and fixed in a state where the end surface 14a of the piston rod is in contact with the processed part back surface of the workpiece.
In the processing step S3, the workpiece is processed with the piston rod fixed in the fixing step.

  In the abutting step S1, the pressing force of the piston rod 14 is set to a minute force that hardly generates deformation or internal stress in the processed portion of the workpiece, whereby the deformation or internal stress is applied to the processed portion of the workpiece. It is possible to firmly support the workpiece against a large machining resistance without generating almost any of the above.

  In the contact step S1, a simulation is performed in consideration of the deformation of the workpiece, and the result is fed back to compensate for the pressing force of the piston rod 14 and the amount of deformation due to the weight of the machining portion of the workpiece or the external force of the machining. By setting the force to such a magnitude, the machining portion of the workpiece can be machined by applying a magnitude force that compensates for the amount of deformation due to its own weight or external machining force.

  According to the method of the present invention described above, the piston rod is brought into contact with the back of the processed part of the workpiece in the contact step S1, and in this state, the piston rod 14 is held and fixed in the fixing step S2, and the machining is performed in this state. Since the workpiece is processed in step S3, the workpiece can be firmly supported against a relatively large processing resistance (for example, about 10 kg or more) even if the workpiece is a thin-walled member. Deformation of the workpiece during machining can be greatly reduced.

FIG. 4 is an overall configuration diagram of the ELID grinding apparatus used in the test. The ELID grinding apparatus 30 includes a conductive grindstone 31, an electrode 32, a pulse power source 33, and an electrolyte supply nozzle 34, and grinds the conductive grindstone 31 while performing dressing by electrolysis.
In this example, the workpiece 1 (workpiece) is attached to the upper surface of the rotary table 2 and rotated, and the upper surface is mirror-polished into a predetermined shape by a cylindrical grindstone 31. The ELID grinding apparatus 30 is preferably numerically controlled for each axis.
With this configuration, even a hard material such as SiC can be mirror-finished with low processing resistance and high efficiency.

  FIG. 5 is an appearance photograph of the front surface (left) and the back surface (right) of the workpiece 1 (work) used in the test. The workpiece 1 is a SiC material having a diameter of 80 mm, a thickness of 3 mm, and a triangular rib portion provided on the back surface.

  FIG. 6 is a diagram showing the surface shape after processing. As a result of processing by ELID grinding, an excellent mirror surface with Ry = 87 nm and Ra = 11 nm was obtained. From this figure, a bulge (convex portion) of about 330 nm at maximum remains inside the triangular rib portion. all right. The cause is deformation of the workpiece being processed.

FIG. 7 is a schematic diagram showing a method for reducing the deformation of FIG. In this figure, (A) is a conventional example, and (B) is a method of the present invention.
In the conventional example (A), the trajectory of the grindstone is numerically controlled as shown in the left figure. However, since deformation of the workpiece is not taken into consideration, as shown in the right figure, the thin part of the workpiece is subjected to cutting force during machining. Since it escapes, a convex part will be formed in a processing part.
On the other hand, in the example (B) of the present invention, as shown in the left figure, a simulation is performed in consideration of the deformation of the workpiece, and the result is fed back to numerically control the trajectory of the grindstone. Thereby, since the deformation | transformation of a workpiece | work is considered, as shown in the right figure, the thin part of a workpiece can also be processed into a defined shape.
In the example (B) of the present invention, the above-described preload support is used, and the pressing force of the piston rod is set to a force that is large enough to compensate for the amount of deformation of the processed portion of the workpiece due to its own weight or external processing force. Is preferred.

  FIG. 8 is a diagram showing a trial calculation of grinding force during processing by ELID grinding. From this figure, it can be seen that the grinding force during processing increases as the grinding depth and rotational speed increase. Further, it can be seen that the grinding force during this processing is about 2 to 4 kg, and it is necessary to prevent the processed portion from being deformed by this force.

  FIG. 9 shows the result of trial calculation of the deformation amount of the workpiece 1 (workpiece) by the finite element method. From this figure, it can be seen that the maximum deformation at the center is about 316 nm under the same conditions as in the above test, which is in good agreement with the test results. Accordingly, it can be understood that it is feasible and effective to perform a simulation in consideration of the deformation of the workpiece and feed back the result to numerically control the trajectory of the grindstone.

FIG. 10 is a plan view of an enlarged workpiece 1 (workpiece) based on the result of the first embodiment. In this figure, (A) is a cross-sectional view and (B) is a plan view.
The workpiece 1 (workpiece) having a large size is a SiC material having a diameter of 360 mm, a thickness of 5 mm, and a plurality of triangular rib portions having the same size on the back surface. It can be seen that with this configuration, although the diameter is 4.5 times that of Example 1, the thickness is substantially the same, and the overall weight can be reduced. Moreover, since it is comprised by the triangle of the same magnitude | size, it can estimate | forecast that the deformation amount of the center part will be comparable as Example 1. FIG.

  FIG. 11 is a diagram showing a state in which the workpiece 1 (workpiece) of FIG. 10 is fixed using the preload support of the present invention. In this figure, (A) is a cross-sectional view and (B) is a plan view.

  In this example, as shown in the drawing, in addition to the support points (three points) that serve as a reference for the enlarged workpiece 1, the inside of the triangular rib portion is also supported by the preload support 10 of the present invention. Further, the outer peripheral surface of the workpiece 1 is also held by another preload support 10 ′ having the same configuration as the preload support 10.

  With this configuration, deformation inside the triangular rib portion can be reduced.

As described above, an O-ring or the like is generally used for the seal between the piston and the cylinder, but the present invention does not use an O-ring or the like to minimize sliding resistance, and drives the piston. Oil mist is mixed in the air used for the oil and the sealing effect of the oil is used to minimize the sliding resistance, thereby smoothing the operation of the piston.
It can be said that mixing oil mist with air and applying a seal reduces the functions (pressurization and bearing) by one from the conventional two. In addition, by constantly discharging air, it has an air purge effect that prevents intrusion of coolant and foreign matter.
In the present invention, the support force can be controlled over a wide range by minimizing the sliding resistance. In addition, a constant support force can be reproduced over the entire stroke.
Furthermore, by combining the technique for minimizing the sliding resistance of the present invention and the clamp by elastic deformation, it is possible to perform clamping without being displaced while being supported by a small constant pressure.
Further, it is possible to obtain a preload in any direction such as a horizontal / vertical direction depending on the structure of the pressure piston portion.

Further, by utilizing the present invention, it is possible to reproduce a small pressure with a small size, so that it is possible to broaden the scope of application to various fields other than the ultra-precision machining field.
For example, it is a support that can control the contact pressure to prevent deformation and deformation when processing thin products, and automatically calculates and sets a constant pressure in advance for parts that deform due to their own weight or processing external force By giving it, deformation can be canceled and an ideal receiving surface can be constructed.
In addition, it is possible to obtain a preload in any direction, such as horizontal and vertical directions, depending on the structure of the pressurizing piston, and by using n, it can be applied to thin workpieces with complex shapes (such as X-ray observation mirrors). .
Further, by utilizing the present invention, it can be applied to a small-sized and thin-walled product support for deformation prevention cutting of ultra-small hard disks, an apparatus for actively visualizing wind power by adjusting pressure, and the like.
When processing thin products, the support and workpiece are brought into contact with each other so as not to cause processing deformation. By controlling the contact pressure, an effect of preventing chatter can be expected.

  Note that the present invention is not limited to the above-described embodiments and examples, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

It is sectional drawing which shows 1st Embodiment of the preload support of this invention. It is sectional drawing which shows 2nd Embodiment of the preload support of this invention. FIG. 3 is a flow diagram illustrating the method of the present invention. It is a whole block diagram of the ELID grinding apparatus used for the test. It is the external appearance photograph of the surface of the to-be-processed object 1 (work) used for the test. It is a figure which shows the surface shape after a process. It is a schematic diagram which shows the method of reducing a deformation | transformation. It is the figure which calculated the grinding force during processing by ELID grinding. This is a result of trial calculation of the amount of deformation of the workpiece (workpiece) by the finite element method. It is a plan figure of the workpiece (workpiece) enlarged. It is a figure which shows the state which fixed the workpiece (workpiece | work) of FIG. 10 using the preload support of this invention. 1 is a configuration diagram of a “collet clamp” in Patent Document 1. FIG.

Explanation of symbols

1 Workpiece (work), 2 Rotary table,
10 preload support, 12 piston, 14 piston rod, 14a one end surface,
16 cylinder, 16a gas chamber, 16b oil chamber,
17a inner wall, 17b outer wall,
22 Air source, 23 Pressure control valve, 24 Hydraulic source, 25 Non-leak valve,
30 ELID grinding device, 31 conductive grinding wheel, 32 electrodes,
33 Pulse power supply, 34 Electrolyte supply nozzle

Claims (6)

A cylindrical piston, a cylindrical piston rod concentrically connected to the piston and extending in the axial direction; and a cylinder for guiding the piston and the piston rod so as to be movable in the axial direction;
The cylinder includes a cylindrical gas chamber that accommodates a piston movably in the axial direction with the pressure of a gas supplied to the inside, and a hollow cylindrical oil chamber that surrounds the piston rod and is supplied with hydraulic pressure. Have
When the oil pressure is lower than a predetermined low pressure, the inner wall of the oil chamber forms a minute gap communicating with the gas chamber between the piston rod and the gas passing through the minute gap from the gas chamber. Is configured to minimize the sliding resistance of
When the hydraulic pressure is higher than a predetermined high pressure, the inner wall is swelled inward by elastic deformation to grip and fix the piston rod, and the sliding resistance is maximized. Preload support. An air source capable of supplying air containing oil mist to the gas chamber, and a pressure control valve capable of finely adjusting the pressure of the air,
The pressure of the air is set to an extremely low pressure at which the piston and the piston rod move toward the workpiece and abuts against the workpiece with a minute force that hardly generates deformation or internal stress. The preload support according to claim 1. The preload support according to claim 1, comprising: a hydraulic pressure source capable of supplying a hydraulic pressure of a predetermined pressure to the oil chamber; and a non-leak valve capable of sealing the hydraulic pressure so as not to leak. An abutting step for abutting a cylindrical piston rod having an end surface supporting the workpiece on the back side of the processed part of the workpiece;
A fixing step of gripping and fixing the piston rod in a state where the end surface is in contact with the processing portion rear surface of the workpiece;
And a processing step of processing a processed portion of the workpiece while the piston rod is fixed in the fixing step. 5. The thin-walled member according to claim 4, wherein, in the abutting step, the pressing force of the piston rod is set to a minute force that hardly causes deformation or internal stress in a processed portion of the workpiece. Precision machining method. In the abutting step, a simulation is performed in consideration of the deformation of the workpiece, the result is fed back, and the pressing force of the piston rod compensates for the amount of deformation due to the workpiece's own weight or machining external force. The ultra-precision machining method for a thin-walled member according to claim 4, wherein

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