Gas bearing pad

Abstract

A gas bearing pad has: a main body portion having a recess; a porous body fitted to the recess of the main body portion; and a bolt inserted into a bolt insertion hole provided in the porous body to fix the porous body to the main body portion. A gas bearing is formed between the porous body and a base by blowing compressed gas from the main body portion through the porous body. A counterbore to accommodate a head portion of the bolt is provided in the bolt insertion hole. A space is provided in the counterbore between a head top surface of the head portion of the bolt opposite the guide surface and a bearing surface of the porous body opposite the guide surface.

Description

Technical Field

[0001] This invention relates to gas bearing pads, for example to gas bearing pads used in machine tools, precision machinery, and ultra-precision machinery for horizontal movement of objects. Background Technology

[0002] As a conventional gas bearing pad, one known gas bearing pad comprises: a main body having a recess on its surface; a porous body that fits into the recess of the main body; and a bolt inserted into a bolt insertion hole provided in the porous body to fix the porous body to the main body. The gas bearing pad has a countersunk hole in the bolt insertion hole for receiving the bolt head (see, for example, Patent Document 1). Furthermore, in Patent Document 1, the head of the bolt used to fix the porous body to the main body is machined, and the cutting surface of the bolt head is formed to be flush with the bearing surface of the porous body.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 2811867 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, typically, the porous material in gas bearing pads is formed of graphite or similar materials, while the main body is formed of ceramic or similar materials, both using high-hardness materials. In contrast, the bolts that fix the porous material to the main body are generally formed of iron-based materials with lower hardness.

[0008] Furthermore, in the gas bearing pad described in Patent Document 1, if a foreign object intrudes between the gas bearing pad and the base during operation, the intruding foreign object may become trapped between the bolt head and the base, potentially causing the bolt head to sinter onto the base. Additionally, in the event of a power outage or other situation where there is no gas supply, the bolt head may be grounded to the base and dragged, potentially causing the bolt head to sinter onto the base. If such sintering occurs, the bolt head will be fused to the base, preventing the gas bearing pad from floating.

[0009] The present invention was made in view of the above-mentioned problems, and its object is to provide a gas bearing pad that can prevent the head of the bolt from sintering into the base.

[0010] Technical means for solving problems

[0011] The above-mentioned objective of the present invention is achieved by the following structure.

[0012] (1) A gas bearing pad comprising: a main body disposed on a base having a guide surface and having a recess on a facing surface opposite to the guide surface; a porous body fitted into the recess of the main body; and a bolt inserted into a bolt insertion hole provided in the porous body to fix the porous body to the main body, wherein a gas bearing is formed between the porous body and the base by blowing compressed gas from the main body through the porous body toward the base, wherein a countersunk hole is provided in the bolt insertion hole to receive the head of the bolt, and a space is provided in the countersunk hole between the top surface of the bolt head facing the guide surface and the bearing surface of the porous body facing the guide surface.

[0013] (2) According to the gas bearing pad described in (1), when forming the gas bearing, the gap dimension from the bearing surface of the porous body to the top surface of the bolt head is greater than the gap dimension from the guide surface to the bearing surface of the porous body.

[0014] Invention Effects

[0015] According to the present invention, a space is provided in the countersinking between the top surface of the bolt head facing the guide surface and the bearing surface of the porous material facing the guide surface. Therefore, even if foreign matter intrudes between the gas bearing pad and the base during operation, the intruding foreign matter will enter the space and will not be trapped between the bolt head and the base, thus preventing the bolt head from sintering into the base. Furthermore, even if there is no gas supply due to a power outage, the bolt head does not contact the base, thus preventing the bolt head from sintering into the base. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view illustrating one embodiment of the gas bearing pad involved in the present invention.

[0017] Figure 2 yes Figure 1 The image shows a bottom view of the gas bearing pad.

[0018] Explanation of reference numerals in the attached figures

[0019] 10 Gas bearing pads

[0020] 11. Base

[0021] 11a Guide surface

[0022] 20 Main body

[0023] 20a Opposite surface

[0024] 21 recess

[0025] 22 Gas Flow Path

[0026] 30 porous bodies

[0027] 30a bearing surface

[0028] 31 Bolt through hole

[0029] 32 countersunk holes

[0030] 33 slots

[0031] 40 bolts

[0032] 41. Head

[0033] 41a Top of the head

[0034] SP Space

[0035] S1 is the clearance dimension from the bearing surface of the porous material to the top surface of the bolt head.

[0036] S2 is the clearance dimension from the guide surface of the base to the bearing surface of the porous material. Detailed Implementation

[0037] Hereinafter, an embodiment of the gas bearing pad according to the present invention will be described in detail with reference to the accompanying drawings.

[0038] like Figure 1 as well as Figure 2 As shown, the gas bearing pad 10 of this embodiment includes: a main body 20 disposed on a base 11 having a guide surface 11a, and having a recess 21 on a facing surface 20a opposite to the guide surface 11a; a porous body 30 that fits into the recess 21 of the main body 20; and a bolt 40 inserted into a bolt through hole 31 provided in the porous body 30 to fix the porous body 30 to the main body 20. The main body 20 is formed of ceramic or the like, the porous body 30 is formed of graphite or the like, and the bolt 40 is formed of an iron-based material such as steel.

[0039] The main body 20 is rectangular in shape, and a circular recess 21 is formed on the opposing surface 20a opposite to the guide surface 11a. In addition, a gas flow path 22 is formed in the main body 20, which supplies compressed gas (not shown) to the porous body 30 in the recess 21.

[0040] The porous body 30 is in the shape of a circular plate. The bearing surface 30a of the porous body 30, which faces the guide surface 11a, is formed to be on the same plane as the opposing surface 20a of the main body 20. Furthermore, a bolt insertion hole 31 is formed in the center of the porous body 30. A countersunk hole 32 for receiving the head 41 of a bolt 40 is formed on the bearing surface 30a side of this bolt insertion hole 31. Additionally, on the side of the porous body 30 opposite to the bearing surface 30a... Figure 1 The upper surface of the porous body 30 has an annular groove 33 centered on the bolt insertion hole 31, which serves as a flow path for compressed gas. The porous body 30 is a porous material with an appropriate air permeability.

[0041] Furthermore, in this embodiment, the countersunk hole 32 of the bolt insertion hole 31 is formed to a depth greater than the thickness of the head 41 of the bolt 40. Therefore, in the countersunk hole 32, a space SP is formed between the top surface 41a of the head 41 of the bolt 40, which faces the guide surface 11a, and the bearing surface 30a of the porous body 30.

[0042] In addition, in this embodiment, when forming the gas bearing, the gap size S1 from the bearing surface 30a of the porous body 30 to the top surface 41a of the head 41 of the bolt 40 is set to be greater than the gap size S2 from the guide surface 11a of the base 11 to the bearing surface 30a of the porous body 30.

[0043] In the gas bearing pad 10 configured in this way, compressed gas is blown from the gas flow path 22 of the main body 20 toward the guide surface 11a of the base 11 via the porous body 30, thereby forming a gas bearing between the porous body 30 and the base 11. As a result, the gas bearing pad 10 can move relative to the guide surface 11a of the base 11 in a non-contact state.

[0044] As explained above, in the gas bearing pad 10 of this embodiment, a space SP is formed in the countersunk hole 32 between the top surface 41a of the bolt head 41 and the bearing surface 30a of the porous body 30. Therefore, even if foreign matter intrudes between the gas bearing pad 10 and the base 11 during operation, the intruding foreign matter will enter the space SP and will not be trapped between the bolt head 41 and the base 11, thus preventing the bolt head 41 from sintering with the base 11. Furthermore, even if there is no gas supply due to a power outage, the bolt head 41 is not grounded to the base 11, thus preventing the bolt head 41 from sintering with the base 11.

[0045] Furthermore, according to the gas bearing pad 10 of this embodiment, since the gap size S1 from the bearing surface 30a of the porous body 30 to the top surface 41a of the head 41 of the bolt 40 is set to be greater than the gap size S2 from the guide surface 11a of the base 11 to the bearing surface 30a of the porous body 30, even if the driving of the gas bearing pad 10 is stopped when foreign matter intrudes between the gas bearing pad 10 and the base 11, since the intruding foreign matter will not be trapped between the head 41 of the bolt 40 and the base 11, the head 41 of the bolt 40 can be prevented from sintering into the base 11.

[0046] Furthermore, according to the gas bearing pad 10 of this embodiment, the space SP of the countersunk hole 32 becomes an air pocket, so the pressure is constantly accumulated in the space SP, which can suppress the self-excited vibration caused by the air film.

[0047] Furthermore, the present invention is not limited to the embodiments described above, and appropriate modifications can be made without departing from the spirit of the present invention.

[0048] For example, the shape of the main body and the porous material, the presence or absence of annular grooves in the porous material, and the shape of the gas flow path can be freely set.

[0049] This application is based on Japanese Patent Application 2021-062325, filed on March 31, 2021, the contents of which are incorporated herein by reference.

Claims

1. A gas bearing pad, characterized in that, have: The main body is disposed on a base having a guide surface and has a recess on an opposing surface opposite to the guide surface; A porous material, the porous material being fitted into the recess of the main body; and A bolt is inserted into a bolt through-hole provided in the porous material to fix the porous material to the main body. By blowing compressed gas from the main body toward the base via the porous material, a gas bearing is formed between the porous material and the base, wherein... A countersunk hole is provided in the bolt insertion hole to accommodate the head of the bolt. In the countersinking, a space is provided between the top surface of the bolt head facing the guide surface and the bearing surface of the porous material facing the guide surface. When forming the gas bearing, the clearance dimension from the bearing surface of the porous body to the top surface of the bolt head is greater than the clearance dimension from the guide surface to the bearing surface of the porous body. The space within the countersunk hole becomes an air pocket, where pressure is constantly accumulated, suppressing self-excited vibrations caused by the air film.

Images