JP2001150327A - Polishing method using fluid abrasive mixed with subliminate material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize abrasives for preventing overheat of the abrasives. SOLUTION: Granular materials 26 to be subliminated at the temperature of abrasives during polishing are mixed in fluid abrasives besides abrasive grains 22. By using the abrasives, when the temperature of the abrasive grain rises to some extent during polishing, subliminate materials 26 contained in the abrasives are subliminated. In sublimination, since heat is absorbed from the abrasives, the abrasives are effectively cooled, and a base material can be prevented from being softened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polishing using a fluid abrasive in which a large number of abrasive grains are dispersed in a fluid matrix. In particular, the present invention relates to a technique for polishing the surface to be polished by flowing the fluid abrasive along the surface to be polished in a pressurized state.

[0002]

2. Description of the Related Art The above polishing technique is described in Japanese Patent Application Laid-Open No. Hei 6-179234. This technique will be described with reference to FIG. FIG. 1 illustrates a case in which the inner surface 10a of a substantially cylindrical workpiece 10 is polished, in which a polishing apparatus and a part of the workpiece are cut away to show the inside. In this polishing apparatus, a cylindrical work 10 is sandwiched between an upper cylinder 18 and a lower cylinder 20. An upper work mount 8 is fixed to a lower end of the upper cylinder 18, and a lower work mount 12 is fixed to an upper end of the lower cylinder 20. Openings are provided in the respective work mounts 8 and 12. Therefore, when the cylindrical work 10 is sandwiched between the upper cylinder 18 and the lower cylinder 20 via the work mounts 8 and 12, the upper chamber 4, the lower chamber 14, and the inner space of the work 10 Communicate with each other to create a closed space 21 which is isolated from the atmosphere. In this sealed space 21, fluid abrasive 6
Is filled. The upper piston 2 is located above the closed space 21 filled with the fluid abrasive 6,
A lower piston 16 is located on the lower side, and an upper hydraulic cylinder (not shown) is connected to the upper piston 2,
A lower hydraulic cylinder (not shown) is connected to the lower piston 16. As shown schematically in FIG. 3, the fluid abrasive 6 used in this technique has a large number of abrasive grains 22 mixed in a fluid matrix 24 such as a viscoelastic resin, an organic medium, or a liquid. Things.

When the polishing method is executed, a force of 120 kg is applied to the upper piston 2 downward while the lower piston 16 is urged upward with a force of 100 kg. As a result, the closed space 21 filled with the fluid abrasive 6 is 1
It is pressurized by a force of 00 kg, and the upper and lower pistons 2 and 16 descend at the same speed in the pressurized state. The fluid abrasive 6 pressurized along with the downward movement causes the polished surface 10 inside the work 10 to be polished.
Flowing from top to bottom along a, the polished surface 10a inside the work 10 is polished. When the upper piston 2 reaches the bottom dead center, a force of 120 kg is applied upward to the lower piston 16 with the upper piston 2 urged downward with a force of 100 kg. Thereby, the pressurized fluid abrasive 6 flows upward from below along the polished surface 10a inside the work 10, and the polished surface 10a inside the work 10 is turned on.
Is polished. By repeatedly reversing the vertical movement of the pistons 2 and 16, the polishing operation can be continued for a long time.

[0004] Surprisingly, even if the polishing operation is continued for a long time by the above-mentioned apparatus, the progress of polishing does not proceed as expected. As a result of earnestly studying the cause, it was confirmed that the polishing did not proceed because the temperature of the fluid abrasive 6 increased. That is, the upper and lower pistons 2, 1
6 is repeatedly moved up and down, the temperature of the fluid abrasive 6 rises. When the temperature of the flowable base material 24 rises, the flowable base material 24 is softened and easily flows. During polishing, work 1
Since the fluid base material 24 at the portion in contact with 0 is cooled by the work 10, the flow base material 24 has a high temperature in the central portion and has a low temperature in the polishing section in contact with the work 10. That is, during polishing, the fluid base material 24 tends to flow at the central portion, and hardly flows at a portion in contact with the workpiece 10 that contributes to polishing. Even if the polishing operation is continued for a long time in this state, the polishing does not proceed as expected. When the temperature of the abrasive further increases, the flowable base material 2
4 deteriorates and the polishing action cannot be obtained.

A technique for preventing the temperature of the abrasive 6 from increasing during polishing has been developed.
A method of cooling the fluid abrasive 6 from the outside by providing a cooling water passage around the periphery of the lower cylinder 8 and the lower cylinder 20 is known. This type of technology, that is, a technology of cooling the fluid abrasive 6 with a cooling device, is disclosed in Japanese Patent Application Laid-Open Nos. 8-243902 and
No. 0-180621.

[0006]

In the technology in which a cooling device is added to the polishing apparatus, it is difficult to effectively cool the central portion of the fluid abrasive, and the above-mentioned phenomenon in which the polishing efficiency is reduced is effectively suppressed. Difficult to do. In addition, there is a need to improve the apparatus itself, which leads to an increase in cost, and a problem that the cooling apparatus extends to the work space and impairs the workability. The present invention was created in an attempt to realize a technique capable of preventing a rise in the temperature of an abrasive without using a special cooling device.

[0007]

The polishing method of the present invention is an improved method of polishing a surface to be polished by flowing a flowable abrasive which is pressurized along the surface to be polished. Further, in addition to the abrasive grains, a fluid abrasive in which a particulate substance that sublimes at the temperature of the abrasive being polished is mixed is used. According to this method, when the temperature of the abrasive rises to some extent during polishing, the sublimable substance contained in the abrasive sublimes, and the abrasive is effectively cooled because heat is absorbed from the abrasive during the sublimation, The softening of the fluid base material can be prevented, and the polishing ability of the abrasive can be maintained at a high level during a long polishing operation. In this way, efficient polishing can be continued for a long time.

The sublimable substance used in the present invention is defined as the temperature of the polishing agent during polishing (although the temperature rise is suppressed by cooling due to the sublimation of the sublimable material mixed in, the temperature of the polishing agent is reduced by polishing. (Substance that rises to some extent during work)), and refers to a substance that sublimates below, typically exemplified by dry ice and camphor. Although it is not physically strict sublimation that changes directly from the solid phase to the gas phase, the temporary change of the liquid phase to a temporary liquid phase has a substantial effect on the polishing ability and the deterioration of the abrasive. Those that do not exist are also included in the sublimable substance here.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a polishing method or an abrasive, and a conventional polishing apparatus can be used as it is. For example, the conventional polishing apparatus illustrated in FIG. 1 can be used as it is. Since the description of the polishing apparatus has been given earlier, it will not be repeated here.

In this embodiment, an abrasive 6 is used as shown in FIG.
Is used. The abrasive 6 has a base material of a viscoelastic resin 24 which flows when pressurized, and a number of abrasive grains 22 and dry ice grains 26 are dispersed therein.

When this polishing agent 6 is polished by the polishing apparatus shown in FIG. 1, the dry ice grains 26 sublime in response to the temperature rise of the polishing agent 6, thereby cooling the polishing agent 6. As a result, the temperature of the abrasive 6 during polishing is temporarily reduced to the dry ice particles 2.
If the temperature is not dispersed, the temperature is kept lower than the temperature at which the temperature rises. Therefore, during the execution of the polishing method, the state in which the fluid base material 24 contained in the abrasive 6 is not softened by heat can be maintained for a long time, and the polishing operation can be performed while maintaining the state of high polishing efficiency. Can last.

In order to keep the polishing agent 6 at a relatively low temperature during the execution of the polishing method, the dry ice particles 26 gradually sublime, and carbon dioxide gas bubbles are generated in the polishing agent 6. Since the abrasive 6 flows as a whole, the air bubbles are quickly released to the atmosphere from the minute clearance between the work 10 and the work mount 8 and from the minute clearance between the work 10 and the work mount 12. You.

Since the abrasive 6 uses dry ice which directly changes from a solid phase to a gas phase without passing through a liquid phase, it changes the viscosity of the abrasive 6, especially its base material (viscoelastic resin) 24. It does not cause deterioration or quality deterioration, and does not reduce the service life of the abrasive 6.

[0014]

The fluid abrasive of the present invention has a wide range of application because it can be used in a conventional polishing apparatus. Further, there is no need to improve the apparatus for maintaining the polishing efficiency over a long period of time, and the apparatus can be introduced at low cost. Further, since the fluid abrasive is prevented from being overheated during polishing, the work can be prevented from being overheated, and the desired dimensional accuracy cannot be obtained as a result of the work being polished in a thermally expanded state. In addition, it is possible to prevent the workpiece from being unintentionally heat-treated.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a polishing apparatus that performs a polishing method.

FIG. 2 is a diagram schematically showing an abrasive according to the embodiment.

FIG. 3 is a diagram schematically showing a conventional abrasive.

[Explanation of symbols]

2: Upper piston 4:
Upper chamber 6: Abrasive 8:
Upper work mount 10: Work 10a:
Surface to be polished 12: Lower work mounting base 14:
Lower chamber 16: Lower piston 18:
Upper cylinder 20: Lower cylinder

Claims (1)

[Claims] 1. A method of polishing a surface to be polished by flowing a flowable abrasive pressurized along the surface to be polished, wherein the granular material sublimates at the temperature of the polishing agent being polished in addition to the abrasive grains. A polishing method comprising using a flowable abrasive in which a substance is mixed in a flowable base material.