JP2000346164A - Porous hydrostatic gas screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the utilizing efficiency of a supplied high pressure gas to improve the rigidity of the meshing part of a screw and prevent the unstable vibration thereof by fixing a hollow porous sintered metal layer having a cylindrical threaded circumferential surface to the inside of a screw base having a circumferential surface, and supplying the high pressure gas between the both. SOLUTION: This screw has a cylindrically formed screw base 3 consisting of a metal selected from iron and iron alloys and a hollow cylindrical porous sintered metal layer 9 having a cylindrical threaded inside surface 5 having a trapezoidal female thread 4 formed thereon an a cylindrical outside surface 7 as the opposite circumferential surface opposed to the inside surface 5, and fitted and fixed to the inside surface 2 of the screw base 3 in the outside surface 7. A feed screw shaft 32 is screwed into the hollow part of the porous sintered metal layer 9 with a minute clearance in the meshing part between the female thread 4 and a male thread 31, and a high pressure gas supplied to a spiral groove 21 through an inlet port 22 is then blow out from the pores on both spiral inclined surfaces of the female thread of the inside surface 5 to form a gas film in the meshing part between the female thread 4 and the male thread 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static pressure gas screw, and more particularly, to a porous static gas screw having a porous sintered metal layer.

[0002]

A static pressure gas screw used for a feed mechanism of a movable body or the like has a gas film formed at a meshing portion between a male screw and a female screw to form a feed screw shaft or a nut by an electric motor or the like. In order to move the movable body through the gas film by relative rotation, preferably manufactured static pressure gas screw does not require lubrication oil and lubrication at the meshing part, and the movable body has high precision with low friction and low heat generation It can move preferably.

[0003] As one of the static pressure gas screws, a porous static pressure gas screw provided with a porous sintered metal layer for jetting a high-pressure gas to an engagement portion ejects a high-pressure gas to the engagement portion. Therefore, even if you do not particularly drill injection nozzle holes,
It is very preferable because high-pressure gas can be ejected from many pores on the surface of the porous sintered metal layer having gas permeability, but in the porous sintered metal layer, many pores are present on the entire surface. Therefore, high-pressure gas is ejected from unnecessary parts, lowering the efficiency of use of the supplied high-pressure gas, reducing the rigidity of the meshing portion, and thus causing unstable vibration to cause the feed mechanism to fail. There is a possibility that positioning accuracy may be reduced.

On the other hand, as a material for forming a porous sintered metal layer, a material mainly composed of bronze, an aluminum alloy, and stainless steel, particularly a material mainly composed of bronze, is often used. The porous sintered metal layer itself has a preferable air permeability, but the dimensional accuracy and the surface roughness of the porous sintered metal layer are not sufficient, so that in many cases, a bearing of the order of 10 ⁻³ mm is used. In order to obtain a surface roughness, the surface which will be the bearing surface is further machined.

[0005] This machining is mainly performed by a lathe, milling or grinding, and the lathe, milling or grinding causes clogging on the surface of the porous sintered metal layer, and its air permeability (drawing property). Will be greatly affected. In particular, in grinding, plastic flow is induced on the surface of the porous sintered metal layer to cause burrs and burrs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a gas film at a meshing portion of a screw without forming an injection nozzle hole or the like. It is to provide a porous hydrostatic gas screw that can be formed.

Another object of the present invention is to increase the utilization efficiency of the supplied high-pressure gas, improve the rigidity of the screw engagement portion, and thereby prevent unstable vibration. An object of the present invention is to provide a porous static pressure gas screw capable of increasing the positioning accuracy of a feed mechanism.

[0008] It is still another object of the present invention to provide a porous static pressure gas screw having a high pressure gas ejection surface having favorable air permeability and flatness.

[0009]

According to a first aspect of the present invention, there is provided a porous static pressure gas screw comprising: a screw base having a peripheral surface; a cylindrical threaded peripheral surface formed with the screw; A hollow porous sintered metal layer fixed to the peripheral surface of the screw base at the opposed peripheral surface, and a high pressure gas is applied to the opposed peripheral surface of the porous sintered metal layer. And a passage means for supplying

According to the porous static pressure gas screw of the first aspect, since the porous sintered metal layer having the threaded peripheral surface is provided, a high pressure is applied from the threaded peripheral surface of the porous sintered metal layer. As a result of the gas being ejected to the screw engagement portion, a gas film can be desirably formed at the screw engagement portion without particularly forming an injection nozzle hole or the like.

[0011] In the porous static pressure gas screw according to the second aspect of the present invention, in the porous static pressure gas screw according to the first aspect, the screw base is cylindrical and the peripheral surface of the screw base is cylindrical. The porous sintered metal layer is a cylindrical inner surface, and the porous peripheral surface of the porous sintered metal layer is cylindrical, and the porous sintered metal layer is fixed to the inner peripheral surface of the screw base.

According to the porous static pressure gas screw of the second aspect, the porous static pressure gas screw can be preferably used as a nut. In this case, the screw formed on the threaded peripheral surface functions as a female screw. The porous static pressure gas screw as a nut is usually rotatably or fixedly attached to a linear moving body as a movable body.

[0013] In the porous static pressure gas screw according to the third aspect of the present invention, in the porous static pressure gas screw according to the first or second aspect, the passage means is provided on an opposing peripheral surface of the porous sintered metal layer. It comprises a formed spiral groove and a through hole formed in the screw base in communication with the spiral groove.

In the porous static pressure gas screw according to the fourth aspect of the present invention, in the porous static pressure gas screw according to the first or second aspect, the passage means includes a groove formed in the screw base and the groove. And a through hole formed in the screw base.

The passage means may have a spiral groove formed on the opposing peripheral surface of the porous sintered metal layer as in the third embodiment, and may have a screw groove as in the fourth embodiment. It may be configured to include a groove formed in the base, and furthermore, a plurality of independent annular grooves formed on opposing peripheral surfaces of the porous sintered metal layer, and the annular grooves communicate with each other. And a communication hole or a communication groove formed in the opposing peripheral surface or the screw base, and a through-hole formed in the screw base in communication with the annular groove or the communication hole or the communication groove. .

The porous static pressure gas screw according to a fifth aspect of the present invention is the porous static pressure gas screw according to any one of the first to fourth aspects, wherein the thread crest surface of the thread having a threaded peripheral surface and the screw are provided. In order to prevent the high-pressure gas from being ejected from the groove bottom surface, a sealing material formed on the screw crest surface and the screw groove bottom surface is further provided.

In the porous static pressure gas screw according to the fifth aspect, since the top surface of the screw thread and the bottom surface of the screw groove are sealed by the sealing material, the ejection of the high-pressure gas from the top surface of the screw thread and the bottom surface of the screw groove is prevented. Can be prevented, so that the use efficiency of the supplied high-pressure gas can be increased, the rigidity of the screw engagement portion can be improved, and the positioning accuracy of the feed mechanism can be increased without causing unstable vibration. be able to.

According to the porous static pressure gas screw of the sixth aspect of the present invention, in the porous static pressure gas screw of any of the first to fifth aspects, the sealing material is made of an epoxy resin or a phenol resin. .

As the sealing material, as described above, epoxy resin or phenol resin is preferable in that it has a small coefficient of thermal expansion and has heat resistance, but the present invention is not limited to these, and other α- It may be a cyanoacrylate resin or a thermoplastic resin.

[0020] In the porous static pressure gas screw according to the seventh aspect of the present invention, in the porous static pressure gas screw according to any of the first to sixth aspects, the porous sintered metal layer has an inorganic particle at the grain boundary. Material particles are contained.

According to the porous static pressure gas screw of the seventh aspect, since the inorganic particles are contained in the grain boundaries of the porous sintered metal layer, clogging of the porous sintered metal layer is suppressed. As a result, an ideal throttle structure is obtained, and a desired gas film can be formed at the screw engagement portion.

In the porous static pressure gas screw of the present invention, the roughness of the exposed surface of the porous sintered metal layer is set to 10 ⁻³ mm.
In the following, the positioning mechanism of the movable body of the feed mechanism may be configured to have higher positioning accuracy.

According to the porous static pressure gas screw of the eighth aspect of the present invention, in the porous static pressure gas screw of the seventh aspect, the porous sintered metal layer contains at least tin, nickel, phosphorus and copper. Wherein the inorganic substance particles are made of at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide.

In the porous static pressure gas screw according to the ninth aspect of the present invention, in the porous static pressure gas screw according to any one of the first to eighth aspects, the porous sintered metal layer has an opposing peripheral surface. And is fixed to the peripheral surface of the screw base by sintering.

According to the porous static pressure gas screw of the ninth aspect, since it is fixed by sintering, the opposing peripheral surface and the peripheral surface of the screw base can be made close to each other. Outflow of gas can be prevented.

According to the porous static pressure gas screw of the tenth aspect of the present invention, in the porous static pressure gas screw of any of the first to ninth aspects, the screw base is made of iron and an iron alloy, copper and copper. It consists of a metal selected from the group consisting of alloys.

The porous hydrostatic gas screw may be used as a nut as described above, or alternatively, may be used as a screw shaft. When the screw is used as a screw shaft, the screw may be used. The thread on the peripheral surface acts as a male screw, the screw shaft is fixedly installed when the nut screwed into it is turned, and conversely, when the nut is fixed, it is turned. Is installed as follows. The thread on the threaded peripheral surface is preferably a trapezoidal screw from the viewpoint of easiness of processing, but the present invention is not limited to such a trapezoidal thread and may be a metric thread or the like.

[0028]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a preferred embodiment of the present invention. In addition,
The present invention is not limited to these examples.

In FIGS. 1 and 2, the porous static pressure gas screw 1 of this embodiment has a cylindrical inner peripheral surface 2 as a peripheral surface, and is made of iron and an iron alloy, and copper and a copper alloy. Cylindrical screw base 3 made of a metal selected from the group
And a cylindrical threaded inner peripheral surface 5 on which a trapezoidal female screw 4 is formed, and a cylindrical outer peripheral surface 7 as an opposing peripheral surface facing the inner peripheral surface 5. A hollow cylindrical porous sintered metal layer 9 fitted and fixed to the inner peripheral surface 2 of the base 3, a passage means 10 for supplying a high-pressure gas to the outer peripheral surface 7 of the porous sintered metal layer 9, In order to prevent high-pressure gas from being ejected from the thread crest surface 11 and the screw groove bottom surface 12 of the female screw 4, there are provided sealing members 13 and 14 formed on the screw crest surface 11 and the screw groove bottom surface 12. .

The porous sintered metal layer 9 contains at least tin, nickel, phosphorus and copper, and the boundary of the porous sintered metal layer 9 is an inorganic substance that does not undergo plastic deformation. Contains inorganic material particles made of at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide and silicon carbide. When such an inorganic substance is dispersed and mixed in tin, nickel, phosphorus and copper of the porous sintered metal layer 9, the substance itself does not undergo plastic deformation due to mechanical processing,
In addition, since there is a function of dividing and reducing the plastic deformation of the metal part of the base of the porous sintered metal layer 9, clogging of the porous sintered metal layer 9 during machining can be suppressed.

The passage means 10 is formed in the screw base 3 through the spiral groove 21 formed in the outer peripheral surface 7 of the porous sintered metal layer 9 and through the screw base 3 so as to communicate with the spiral groove 21. And an introduction hole 22.

Each of the sealing materials 13 and 14 made of an epoxy resin or a phenol resin is formed by applying an epoxy resin or a phenol resin or by flowing and dipping.

The spiral groove 21 and the porous sintered metal layer 9
In order to prevent the high-pressure gas supplied to the screw base 3 from being discharged to the outside from the both annular end faces 25 and 26 of the screw base 3 without being ejected to the engagement portion of the screw, the sealing material 13 is used.
It is preferable that the same sealing material as that described in (14) and (14) is packed into the openings at both ends of the spiral groove 21 and applied to both end surfaces 27 and 28 of the porous sintered metal layer 9.

In the above porous static pressure gas screw 1,
In the hollow portion of the porous sintered metal layer 9, a feed screw shaft 32 having an external thread 31 having a shape complementary to the internal thread 4 on the outer surface thereof is provided with a small clearance at a portion where the internal thread 4 and the external thread 31 are engaged. Is screwed and inserted. Then, the high-pressure gas supplied to the spiral groove 21 through the introduction hole 22 is supplied to both the spiral inclined surfaces (flanks) 33 and 34 of the female screw 4 on the inner peripheral surface 5.
As a result, a gas film is formed at the portion where the female screw 4 and the male screw 31 mesh with each other.
Is centered and is rotatable relative to the feed screw shaft 32 in the R direction about the central axis O. Here, for example, when the feed screw shaft 32 is rotated in the R direction by an electric motor or the like of the feed mechanism, the porous static pressure gas screw 1 is moved in the H direction, and the porous static pressure gas screw 1 is attached. The moved movable body, for example, the slider is linearly fed in the H direction.

According to the porous static pressure gas screw 1, the female screw 4
Is provided with a porous sintered metal layer 9 having an inner peripheral surface 5 in which a high pressure gas having passed through the porous sintered metal layer 9 can be ejected from the inner peripheral surface 5. A gas film can be desirably formed at a portion where the female screw 4 and the male screw 31 mesh with each other without any drilling.

In the porous static pressure gas screw 1, since the pores of the thread crest surface 11 and the thread groove bottom surface 12 are sealed by a sealing material, the thread crest surface 11 and the thread groove bottom surface 12 are not sealed.
Jet of high-pressure gas from the sloping surfaces 33 and 3
The supply high-pressure gas can be ejected only from the pores of the internal screw 4, and the utilization efficiency of the supply high-pressure gas can be increased.
The rigidity of the meshing portion between the screw and the male screw 31 is improved, and thus the positioning accuracy of the movable body to which the porous static pressure gas screw 1 is attached can be increased without causing unstable vibration.

Further, in the porous static pressure gas screw 1,
Since inorganic substance particles are contained in the grain boundaries of the porous sintered metal layer 9, clogging of the porous sintered metal layer 9 is suppressed, and an ideal drawing structure is obtained. , Female screw 4
A desired gas film can be formed at a portion where the screw and the male screw 31 mesh.

In the porous static pressure gas screw 1, the passage means 10 is constituted by the spiral groove 21 formed on the outer peripheral surface 7 of the porous sintered metal layer 9. Instead of this, as shown in FIG. Without forming the spiral groove 21 on the outer peripheral surface 7 of the porous sintered metal layer 9, the porous sintered metal layer 9 is separated from the inner peripheral surface 2 of the screw base 3 by the smooth cylindrical outer peripheral surface 7. And a plurality of linear grooves 41 and linear grooves 41
Are formed with one or a plurality of annular grooves 42 that communicate with each other, and one of the linear grooves 41 is communicated with the introduction hole 22,
The passage means 45 may be constituted by the introduction hole 22, the straight groove 41 and the annular groove 42.

The porous static pressure gas screw 51 shown in FIG.
The same operation as the porous static pressure gas screw 1 is performed, and substantially the same effect can be obtained.

In the porous static pressure gas screws 1 and 51, the porous sintered metal layer 9 is fitted and fixed to the inner peripheral surface 2 of the screw base 3, but instead of this, the porous sintered metal layer 9 is The metal layer 9 may be fixed to the inner peripheral surface 2 of the screw base 3 by sintering. In this case, the outer peripheral surface 7 and the inner peripheral surface 2 of the screw base 3 can be fixed tightly. It is possible to prevent the outflow of the high-pressure gas from the fixing.

The porous static pressure gas screws 1 and 51 may be used as fixed nuts as described above.
Alternatively, it may be used as a rotating nut rotated by an electric motor or the like.
2 will be fixed.

Further, in the above example, the porous static pressure gas screw of the present invention is used as a nut, but the porous static pressure gas screw may be used as a screw shaft. In the male screw 31 of the feed screw shaft 32, the thread crest surface 1 is attached to the inclined surfaces facing both the inclined surfaces 33 and 34 of the female screw 4.
A recess (a pressure reservoir recess) extending in parallel with one or the thread groove bottom surface 12 may be formed.

A preferred example of a method for manufacturing the porous static pressure gas screws 1 and 51 will be described.
A mixed powder consisting of 10%, 10-40% nickel, 0.5-4% phosphorus, 3-10% graphite and the balance copper is press-formed to form a spiral groove on the outer peripheral surface or a spiral on the outer peripheral surface. Manufacturing a cylindrical green compact with no grooves formed, this green compact,
It is inserted or placed on the inner peripheral surface 2 of a cylindrical screw base 3 made of iron, iron alloy, copper, copper alloy, or the like, and placed at a temperature of 800 to 1150 ° C. in a reducing atmosphere or vacuum at 20 to 60 ° C.
Form by sintering for a minute. During sintering, the surface of the green compact is preferably pressed using an appropriate means, and the green compact is pressed against the screw base 3. As the compacting pressure in the production of compacts,
It is preferably about ² to 7 ton / cm ² . The inner peripheral surface, which is the exposed surface of the porous sintered metal layer material obtained by sintering in this manner, is roughened to form a screw, and after the formation of the screw, the porous sintered On the entire inner peripheral surface of the metal layer material, an epoxy resin or a phenol resin is applied or fluid-immersed to form a sealing film having a uniform thickness serving as a sealing material of the epoxy resin or the phenol resin,
Both inclined surfaces 33 and 34 on the inner peripheral surface of the porous sintered metal layer material
After the portion corresponding to the above is ground to remove the sealing film at this portion, the surface of the porous sintered metal layer at that portion has a roughness of 10%.
^A mechanical process is performed by grinding or lapping so as to have a thickness of ⁻³ mm or less to obtain a porous static pressure gas screw 1 or 51 having a desired porous sintered metal layer 9.

In the obtained porous sintered metal layer 9 of the porous static pressure gas screws 1 and 51, the flow rate of the gas ejected from the porous sintered metal layer 9 is 1/1 / the flow rate of the porous sintered metal layer material before machining. It is about 10/1/30. In addition, the porous sintered metal layer 9 causes mutual diffusion of metal components between the screw base 3 and tightly adheres and integrates, and the adhesion strength is 1000 kg.
/ Cm ² or more, there was no gap between the two, and it was confirmed that there was no leakage of high-pressure gas from this part.

[0045]

According to the present invention, it is possible to provide a porous static pressure gas screw capable of forming a desired gas film at a screw engagement portion without particularly forming an injection nozzle hole or the like.

Further, according to the present invention, the utilization efficiency of the supplied high-pressure gas can be improved, the rigidity of the screw engagement portion can be improved, and the positioning accuracy can be increased without causing unstable vibration. The present invention can provide a porous static pressure gas screw that can be used.

Further, according to the present invention, it is possible to provide a porous static pressure gas screw having a high pressure gas ejection surface having favorable air permeability and flatness.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a preferred embodiment of the present invention.

FIG. 2 is a partially enlarged side view of the example shown in FIG.

FIG. 3 is a sectional view of another example of the preferred embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Porous static pressure gas screw 2, 5 Inner peripheral surface 3 Screw base 4 Female screw 7 Outer peripheral surface 9 Porous sintered metal layer 10 Passage means 11 Thread crest surface 12 Thread groove bottom surface 13, 14 Sealing material

Claims (13)

[Claims] 1. A screw base having a peripheral surface, a cylindrical threaded peripheral surface on which a screw is formed, and an opposing peripheral surface opposed to the threaded peripheral surface. A porous static pressure gas screw, comprising: a hollow porous sintered metal layer fixed to a peripheral surface of the porous sintered metal layer; and a passage means for supplying high-pressure gas to a peripheral surface of the porous sintered metal layer. 2. The screw substrate is cylindrical, the peripheral surface of the screw substrate is a cylindrical inner peripheral surface, and the opposing peripheral surface of the porous sintered metal layer is cylindrical, The porous static pressure gas screw according to claim 1, wherein the porous sintered metal layer is fixed to an inner peripheral surface of the screw base. 3. The passage means comprises a spiral groove formed on the opposing peripheral surface of the porous sintered metal layer, and a through hole formed in the screw base in communication with the spiral groove. 3. The porous static pressure gas screw according to 2. 4. The porous static pressure gas screw according to claim 1, wherein the passage means comprises a groove formed in the screw base, and a through hole formed in the screw base in communication with the groove. . 5. In order to prevent high-pressure gas from escaping from the thread crests and thread groove bottoms of the threads of the threaded peripheral surface, a sealing material is further provided on the thread crests and thread groove bottoms. The porous static pressure gas screw according to any one of claims 1 to 4, wherein: 6. The porous static pressure gas screw according to claim 1, wherein the sealing material is made of an epoxy resin or a phenol resin. 7. The porous static pressure gas screw according to claim 1, wherein the porous sintered metal layer contains inorganic substance particles at grain boundaries. 8. The porous sintered metal layer contains at least tin, nickel, phosphorus and copper, and the inorganic substance particles include graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide and The porous hydrostatic gas screw according to claim 7, comprising at least one of silicon carbide. 9. The porous static pressure gas screw according to claim 1, wherein the porous sintered metal layer is fixed to the peripheral surface of the screw base by sintering on its peripheral surface. . 10. The screw base is made of a metal selected from the group consisting of iron and iron alloys and copper and copper alloys.
10. The porous static pressure gas screw according to any one of claims 1 to 9. 11. The porous static pressure gas screw according to claim 1, wherein the gas is used as a nut or a screw shaft. 12. A feed mechanism comprising the porous static pressure gas screw according to claim 1. Description: 13. A porous static pressure gas screw according to any one of claims 1 to 11, or a screw base or a porous sintered metal layer used in the feed mechanism according to claim 12.