JP2009185926A - Static pressure gas bearing of piston driving mechanism and gas pressure actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a static pressure gas bearing for a piston driving mechanism capable of precluding damage of a bearing sliding surface caused by impact in the radial direction. <P>SOLUTION: The piston driving mechanism 10 has a piston rod 12 and a housing exerting the function of cylinder and is structured so that end plates 24 and 26 in front and in the rear of the housing 20 support the front and rear ends of the piston rod 12 movably in the axial direction, and there the static pressure gas bearing 100 is installed. In this place with static pressure gas bearing 100, metal cylinders 18 and 19 for lubrication formed from a copper-based material are installed in consolidation with the piston rod 12. The metal cylinders 18 and 19 may be provided not at the piston rod 12 but in the static pressure gas bearing part of the housing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a static pressure gas bearing and a gas pressure actuator of a piston drive mechanism including a piston and a cylinder, and more particularly to a static pressure gas bearing that floats and supports a straight shaft of a piston drive mechanism with respect to a housing by gas pressure. The present invention relates to a gas pressure actuator.

  As is well known, a piston drive mechanism including a piston and a cylinder is used in various industrial fields as an actuator using fluid pressure. As the fluid pressure for driving the piston, in addition to hydraulic pressure and vapor pressure, gas pressure such as dry air or inert gas is used. In particular, a gas pressure piston drive mechanism using gas pressure is expected to be an easy-to-handle drive mechanism with less contamination problems than those using hydraulic pressure. For example, a pneumatic servo cylinder is used to suppress vehicle vibration. It is described in Patent Document 1. In this piston drive mechanism, the rectilinear shaft for taking out the driving force to the outside is supported by a bearing with the housing constituting the cylinder. This support bearing structure is for sliding support in the straight direction, but is devised so that fluid pressure is not released by movement in the axial direction. For example, a surface support structure that is precisely finished is used.

Japanese Patent Laid-Open No. 10-129478

  In addition to preventing the vehicle from shaking, a piston drive mechanism using gas pressure has been studied. For example, in a testing machine such as a tension / compression testing machine, it is necessary to accurately control displacement and load, and a piston driving mechanism using gas pressure is expected from the convenience of handling.

  In this case, it is conceivable to adopt a gas bearing structure for the bearing between the linear shaft and the housing. If gas pressure is used for both piston drive and bearing support, contamination will be eliminated and the movement will be smoother. For example, it is expected to improve accuracy in testing machines such as tensile and compression testing machines.

  In the gas bearing structure, gas pressure is supplied to a gap between the linear axis and the housing, and the static axis causes the linear axis to float with respect to the housing. Therefore, when a radial impact of the shaft exceeding the levitation pressure is applied between the rectilinear shaft and the housing, the rectilinear shaft collides with the housing, and the sliding surface of the bearing structure is damaged or deformed to cause a test or the like. Therefore, it may be difficult to perform the operation.

  An object of the present invention is to provide a static pressure gas bearing of a piston drive mechanism and a gas pressure actuator including the same, which can prevent damage to a bearing sliding surface against a radial impact in the piston drive mechanism.

  The static pressure gas bearing of the piston drive mechanism according to the present invention is a static pressure gas bearing that floats and supports the straight shaft of the piston drive mechanism with respect to the housing, and is provided integrally with the straight shaft, and the outer peripheral surface thereof is a static pressure gas bearing. It is characterized by comprising a metal cylinder for lubrication that serves as a gas receiving surface.

  Further, the static pressure gas bearing of the piston drive mechanism according to the present invention is a static pressure gas bearing that floats and supports the linear shaft of the piston drive mechanism with respect to the housing, and is provided at the static pressure gas bearing portion of the housing, and has an inner peripheral surface. Is provided with a metal cylinder for lubrication which becomes a gas ejection surface of a static pressure gas bearing.

  In the static pressure gas bearing of the piston drive mechanism according to the present invention, it is preferable that the lubricating metal cylinder is a cylinder integrated with the straight shaft by shrinking or cooling or bonding.

  Moreover, in the static pressure gas bearing of the piston drive mechanism according to the present invention, the lubricating metal cylinder is preferably a copper-based metal cylinder.

  Further, the gas pressure actuator according to the present invention is provided integrally with a linear shaft connected to the piston, a cylinder housing having a static pressure gas bearing that supports the piston linear shaft so as to be linearly movable, and a piston linear shaft, And a metal cylinder for lubrication whose outer peripheral surface serves as a gas receiving surface for the static pressure gas bearing portion.

  A gas pressure actuator according to the present invention is provided in a linear shaft connected to a piston, a cylinder housing having a static pressure gas bearing portion that supports the piston linear shaft so as to be linearly movable, and a static pressure gas bearing portion of the cylinder housing. And a lubricating metal cylinder whose inner peripheral surface is the gas ejection surface of the static pressure gas bearing.

  According to at least one of the above configurations, the static pressure gas bearing of the piston drive mechanism is provided integrally with the rectilinear shaft, and includes a lubricating metal cylinder whose outer peripheral surface is a gas receiving surface of the static pressure gas bearing. Thus, since the lubricating metal cylinder is provided on the bearing sliding surface, it is possible to prevent damage to the linear shaft or the bearing sliding surface in the housing even if there is a radial impact in the piston drive mechanism. Further, since the metal cylinder for lubrication is provided integrally with the rectilinear shaft and the structure of the static pressure gas bearing itself does not change, the performance of the static pressure gas bearing can be exhibited as it is.

  Further, according to at least one of the above-described configurations, the static pressure gas bearing of the piston drive mechanism is provided in the static pressure gas bearing portion of the housing, and the lubricating metal whose inner peripheral surface is the gas ejection surface of the static pressure gas bearing A tube is provided. Thus, since the lubricating metal cylinder is provided on the bearing sliding surface, it is possible to prevent damage to the linear shaft or the bearing sliding surface in the housing even if there is a radial impact in the piston drive mechanism. Also, since the metal cylinder for lubrication is provided in the static pressure gas bearing of the housing, it is not affected by the stroke length of the linear axis compared with the case where the metal cylinder for lubrication is provided on the linear axis. The length of the metal cylinder can be made short and constant.

  Further, in the static pressure gas bearing of the piston drive mechanism, the lubricating metal cylinder is a cylinder integrated with the linear shaft by shrinking or cooling, or by bonding, and therefore can be firmly integrated with the linear axis.

  Further, in the static pressure gas bearing of the piston drive mechanism, the lubrication metal cylinder is a copper-based metal cylinder, so even if there is a radial impact in the piston drive mechanism, it becomes an appropriate buffer material, and the lubrication metal cylinder It is possible to prevent damage to the linear shaft or the housing, which is the core material covered with the cylindrical material.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, the static pressure gas bearing of the piston drive mechanism used in the tensile compression tester will be described. However, the object to which the static pressure gas bearing of the piston drive mechanism is applied is not limited to such a tester. Any device that floats and supports the rectilinear shaft relative to the housing can be applied. For example, it may be a general actuator that supports a straight shaft with a static pressure gas bearing. The dimensions, materials, etc. used in the following description are examples, and other dimensions may be used as long as the floating support that is a function of the static pressure gas bearing can be sufficiently secured. Any other material may be used as long as the surface can be prevented from being damaged. In addition to the metal cylinder for lubrication, an appropriate lubricant can be used in combination on the bearing surface of the static pressure gas bearing. For example, suitable grease, molybdenum disulfide, or the like can be provided on the bearing surface.

  FIG. 1 is a diagram showing a configuration of a piston drive mechanism 10 for a tension / compression test machine in which a static pressure gas bearing 100 is used. The piston drive mechanism 10 includes a piston rod 12, a housing 20 having a cylinder function, and a gas pressure control valve 40 that supplies a controlled gas pressure. The static pressure gas bearing 100 is provided where the piston rod 12 is supported so as to be movable in the axial direction with respect to the housing 20. Further, a manifold 30 is provided between the gas pressure control valve 40 and the housing 20, and the gas pressure controlled by the gas pressure control valve 40 is guided to the inside of the housing 20 by the control gas flow path 34. The one end of the piston rod 12 is connected to an object of a tensile / compression test via a load cell 16 that detects a load, and the displacement sensor 50 detects the axial displacement of the piston rod 12 at the other end. Is provided.

  In the piston drive mechanism 10, the piston rod 12 has a flange portion 14, divides the interior of the housing 20 into front and rear gas chambers 36 and 38, and the gas chambers 36 and 38 are controlled by a gas pressure control valve 40. The gas pressure is supplied through the control gas flow path 34, and the flange portion 14 is driven to move in the axial direction, that is, the X direction shown in FIG. 1, due to the difference in gas pressure between the front and rear gas chambers 36 and 38. As described above, the piston drive mechanism 10 used in the tension / compression tester moves the piston rod 12 in the axial direction by the gas pressure, and the test object not shown via the load cell 16 provided at the tip of the piston rod 12 is used. It has a function of applying a load to an object and measuring the displacement at that time.

  The piston rod 12 is an elongated rod-like member having a function of a load shaft in a tensile / compression tester, and has a flange portion 14 having a large diameter at a substantially intermediate portion in the axial direction. Since the outer periphery of the flange portion 14 may slide or come into contact with the inner peripheral wall of the housing 20, it is preferable that a sufficiently smooth surface treatment and an appropriate curing treatment be performed as necessary. Further, both end portions of the piston rod 12 are supported by the housing 20 so as to be movable in the axial direction. The portions will be described later so as not to be damaged when a radial impact is applied in the process of the tensile compression test. Lubricating metal cylinders 18 and 19 are provided integrally with the piston rod 12. Such a piston rod 12 can be obtained by processing a metal material having sufficient mechanical rigidity and performing a necessary surface treatment or the like. For example, a material such as high-tensile steel or tool steel can be processed into a cylinder with a flange and subjected to surface hardening treatment, surface polishing treatment, lubrication plating treatment, or the like.

  As described above, the load cell 16 for detecting the load is attached to the one end of the piston rod 12. As the load cell 16, for example, a load table provided with a strain gauge or the like can be used. Further, as described above, the displacement sensor 50 is provided at the other end of the piston rod 12. The displacement sensor 50 may be a differential transformer type. As the displacement sensor 50, a commonly used type such as an optical type or a magnetic type may be used.

  The outputs of the load cell 16 and the displacement sensor 50 are used as they are as load-displacement data of a tension / compression tester, and fed back to a control unit of a tension / compression tester (not shown) to be used as control data for the gas pressure control valve 40. It is done.

  The housing 20 is a one-time airtight housing having a function of accommodating the flange portion 14 of the piston rod 12 inside, projecting both ends of the piston rod 12 to the outside, and guiding and supporting the piston rod 12 so as to be axially movable. Here, the term “airtight” means that the piston rod 12 is sufficiently airtight in terms of the performance of the tensile / compression tester, except when the piston rod 12 is abnormally inclined in the axial direction due to a radial impact or the like. The housing 20 includes a cylinder tube 22 and front and rear end plates 24 and 26. That is, the front and rear end plates 24 and 26 constituting the static pressure gas bearing 100 are respectively disposed between both ends of the piston rod 12 at both side openings of the substantially annular cylinder tube 22, and the cylinder housing as a whole. Configure.

  The cylinder tube 22 is an annular member having an inner diameter slightly larger than the diameter of the flange portion 14 of the piston rod 12. Since the inner peripheral wall may slide or come into contact with the outer periphery of the flange portion 14 of the piston rod 12, it is preferable that the inner peripheral wall be subjected to a sufficiently smooth surface treatment and an appropriate curing treatment as necessary. Such a cylinder tube 22 can be obtained by processing a metal material having sufficient mechanical rigidity and performing a necessary surface treatment or the like. For example, the outer and inner peripheries of a suitable pipe material made of a material such as high-tensile duralumin or stainless steel can be processed into a predetermined size and subjected to surface hardening treatment, surface polishing treatment, lubrication plating treatment, or the like.

  The front and rear end plates 24 and 26 are a pair of members having substantially the same shape. The end plates 24 and 26 have a rod support hole that supports the piston rod 12 through the center, and the opening on both sides of the cylinder tube 22 is closed with the piston rod 12. A member having a function of supporting the piston rod 12 so as to be movable in the axial direction.

  The inner diameter of the rod support hole is slightly larger than the diameters at both ends of the piston rod 12. An exhaust groove 42, a surface restrictor 46, and the like are provided at the rod support hole to constitute the static pressure gas bearing 100 together with the piston rod 12. Details of these will be described later.

  Further, the front and rear end plates 24, 26 have a control gas flow path 34 that guides the controlled gas pressure from the gas pressure control valve 40 to the inside of the housing 20 through the manifold 30. In addition, a stopper 56 is provided for reducing the impact when the piston rod 12 is moved too much in the axial direction and the flange portion 14 collides with the end plates 24 and 26 on the front and rear sides. The front and rear end plates 24 and 26 can be obtained by processing a metal material having sufficient mechanical rigidity and performing a necessary surface treatment or the like. For example, a material such as high-tensile duralumin or stainless steel can be processed into a cylinder with a flange and subjected to surface hardening treatment, surface polishing treatment, lubrication plating treatment, or the like.

  The cylinder tube 22, the front and rear end plates 24 and 26, and the piston rod 12 are assembled in the following procedure. That is, first, the piston rod 12 is passed through the cylinder tube 22. Here, the metal cylinder members 18 and 19 for lubrication are integrally attached to both ends of the piston rod 12 by shrinking or the like as will be described later. Next, the front end plate 24 on the load cell 16 side, the rear end plate 26 on the displacement sensor 50 side, and the end of the piston rod 12 are passed through the rod support holes with the flange portion 14 of the piston rod 12 interposed therebetween. Arrange so that. Then, the front end plate 24 is aligned so as to close the opening of the cylinder tube 22 on the load cell 16 side, and similarly the rear end plate 26 is aligned so as to close the opening of the cylinder tube 22 on the displacement sensor 50 side. Then, the relative positions of the front and rear end plates 24 and 26 are adjusted so that the openings on the manifold 30 side of the control gas channel 34 are aligned on the same plane. When the adjustment is completed, it is confirmed that the control gas channel 34 is fitted between the manifold 30 and the front and rear end plates 24 and 26, and the joint between the cylinder tube 22 and the front and rear end plates 24 and 26 is hermetically sealed. To do. For the hermetic sealing, screwing or the like via a packing such as an O-ring may be used, and when complete hermetic sealing is not required, sealing by a metal mating surface may be used. In this way, an assembly of the housing 20 and the piston rod 12 is obtained, which can be referred to as a piston / cylinder subassembly.

  The manifold 30 is an intermediate member for connecting the gas pressure control valve 40 and the control gas flow path 34 of the housing 20, and has a control gas flow path corresponding to the control gas flow path 34 inside, although not shown. . Such a manifold 30 can be obtained by processing an appropriate metal material or the like. The manifold 30 is tightly connected in an airtight manner so that an internal control gas flow path (not shown) matches the control gas flow path 34 of the piston / cylinder subassembly. For the hermetic connection, screwing using an appropriate hermetic packing or the like can be used.

  The gas pressure control valve 40 is a control valve having a function of generating two controlled gas pressures according to an instruction from a control unit of a tensile / compression tester (not shown). The two controlled gas pressures pass through the control gas flow path inside the manifold 30 and the control gas flow path 34 of the front end plate 24 and the rear end plate 26, respectively, and the front and rear gas inside the housing 20 It is supplied to the chambers 36 and 38. For example, when it is desired to displace the piston rod 12 toward the load cell 16 with a predetermined load, the gas pressure supplied to the gas chamber 38 is made larger than the gas pressure supplied to the gas chamber 36, and the difference in the gas pressures. The gas pressure control valve 40 generates two gas pressures so that a load is obtained by multiplying the pressure by the pressure receiving area of the gas pressure of the flange portion 14. As such a gas pressure control valve, a well-known spool / sleeve type gas pressure control valve or the like can be used.

  Next, the structure of the static pressure gas bearing 100 will be described, particularly the exhaust groove 42 and the surface restriction 46 provided in the rod support hole. The hydrostatic gas bearing 100 is provided at both ends of the piston rod 12, that is, a support portion on the front side of the piston rod 12 in the front end plate 24 and a support portion on the rear side of the piston rod 12 in the rear end plate 26. Each is provided.

  Below, it demonstrates taking the example of the support part of the back side of the piston rod 12. FIG. As described above, since the inner diameter of the rod support hole is slightly larger than the diameter of the end portion of the piston rod 12, there is a gap between the rod support hole of the rear end plate 26 and the piston rod 12. Along the gap, an exhaust groove 42 and a surface restriction 46 are arranged in this order from the end on the rear gas chamber 38 side toward the outside air release 52 side.

  The exhaust groove 42 has a function of collecting the gas leaking from the rear gas chamber 38 through the gap between the rod support hole and the piston rod 12 and flowing it to an exhaust path (not shown). For example, the gas that has entered the exhaust passage can be returned to the control route of the gas pressure again. In other words, the exhaust groove 42 has a function of suppressing the unlimited flow of the gas leaking from the rear gas chamber 38 through the gap between the rod support hole and the piston rod 12 toward the atmosphere opening 52. Have

  The surface restriction 46 is a plurality of shallow grooves provided on the inner wall of the rod support hole, and has a predetermined width, length, and groove depth in the axial direction, and causes the piston rod 12 to float on the principle of a static pressure gas bearing. It has a function. The length of the groove is set so that one end side is sufficiently spaced apart from the exhaust groove 42 in the axial direction, and the other end is sufficiently spaced from the end on the atmosphere opening 52 side. Then, a slightly deeper groove is provided on the inner wall of the rod support hole connecting the substantially central portions of the surface diaphragms 46 along the axial direction, and the opening of the gas supply path 48 is connected thereto. A gas having a predetermined supply pressure is supplied to the gas supply path 48 from a gas source (not shown). In the surface constriction 46 having such a configuration, the high-pressure gas from the gas supply path 48 is guided from the opening and flows along the shallow groove, one toward the exhaust groove 42 and the other toward the end on the atmosphere opening 52 side. Head. When the shallow groove is cut, it is narrowed toward a narrower gap and flows to the low pressure side, that is, the exhaust groove 42 or the atmosphere opening 52 side, so that a so-called surface throttling device is obtained. Due to this throttling effect, a pressure rise occurs at the throttling portion, and the piston rod 12 floats with respect to the rod support hole.

  The depth of the shallow groove of the surface diaphragm 46 is also related to the size of the gap between the rod support hole and the piston rod 12, but in one example, the depth of the shallow groove is set to a neutral gap of about 10 μm. The thickness can be about 10-15 μm. Moreover, the gas pressure supplied to the gas supply path 48 can be set to about 0.5 Mpa.

  Next, the metal cylinders 18 and 19 for lubrication will be described. The lubrication metal cylinders 18 and 19 are soft metal material cylinders provided integrally with the piston rod 12 that is a linear axis, and when a radial impact is applied in the course of a tensile compression test, The piston rod 12 and the housing 20 in the bearing 100 portion have a function of preventing damage. The wall thickness of the cylindrical material may be about several mm, for example. As such metal cylinders 18 and 19 for lubrication, what is called an oilless bearing can be used as a metal bearing that does not require lubrication. The material is preferably copper. An oil-impregnated material is preferable. In some cases, a porous metal material can be used, and the porous material may be used to impart oil content.

  Since the lubricating metal cylinders 18 and 19 are for the purpose of protecting the static pressure gas bearing 100 portion against radial impacts as described above, they are sufficient for the stroke S of the piston rod 12 that is a linear shaft. Must have a certain axial length. FIG. 2 is a view for explaining the required length of the lubricating metal cylinders 18 and 19. Here, the necessary portions are schematically shown in FIG. 1, and the same reference numerals are given to the same elements as those in FIG. Here, regarding the length along the axial direction, that is, the X direction, when the stroke of the piston rod 12 is S, the length of the flange portion 14 is A, and the length of the housing 20 is B, the internal gas chamber of the housing 20 The length is A + 2S. And the length which added the length of the flange part 14 to the length of the metal cylinder materials 18 and 19 for lubrication becomes B + 2S. Therefore, the metal cylinders 18 and 19 for lubrication require {(B + 2S) −A} / 2 as their axial lengths.

  The lubricating metal cylinders 18 and 19 having such a required length are integrated and attached to the piston rod 12 that is a linear shaft. As a method of integration, shrinkage shrinkage, cold shrinkage, adhesion, or the like can be used. FIG. 3 is a view for explaining a state in which the piston rod 12 and the lubricating metal cylinders 18 and 19 are integrated by shrinking or cooling.

  First, as shown in FIG. 3A, the piston rod 12 and the lubricating metal cylinders 18 and 19 are prepared. Here, the inner diameters of the metal cylinders 18 and 19 for lubrication are set smaller than the outer diameters at both ends of the piston rod 12. In the case of fixing by adhesion, for example, an adhesive is applied to the outer periphery of the piston rod 12, the metal cylinders 18 and 19 for lubrication are inserted, and an appropriate adhesion hardening process is performed. Further, when the shrinking method is used, the lubricating metal cylinders 18 and 19 are appropriately heated, their inner diameters are expanded from the normal temperature state, and inserted in both ends of the normal temperature piston rod 12 in that state. . Then, by naturally cooling, the inner diameters of the lubricating metal cylinders 18 and 19 try to return to the original state, and are firmly fixed to the outer peripheral portions of both end portions of the piston rod 12, thereby being integrated. .

  When the cooling swallowing method is used, the piston rod 12 is appropriately cooled, the outer diameter thereof is reduced from the normal temperature state, and the normal temperature lubricating metal cylinders 18 and 19 are connected to the both ends of the piston rod 12 in this state. Insert into each part. When the piston rod 12 is allowed to stand naturally, the outer diameter of the piston rod 12 tends to return to the original state, and is firmly fixed to the lubricating metal cylinders 18 and 19, thereby being integrated.

  The state is shown in FIG. Since the piston rod 12 in which the metal cylinders 18 and 10 for lubrication are integrated is a constituent element of the static pressure gas bearing 100 as described with reference to FIG. It is preferable to make the thickness sufficiently smooth. Therefore, after the integration, it is preferable that the surfaces of the lubricating metal cylinders 18 and 19 are precisely dimensioned by grinding or the like to improve the surface roughness.

  In this manner, the static pressure gas bearing 100 that floats and supports the piston rod 12 that is the linear axis of the piston drive mechanism with respect to the housing 20 is provided integrally with the piston rod 12 that is the linear axis, and the outer peripheral surface is static. By providing the metal cylinders 18 and 19 for lubrication that serve as the gas receiving surfaces of the pressurized gas bearing 100, it is possible to prevent the bearing sliding surface from being damaged by a radial impact in the piston drive mechanism.

  In the above configuration, the lubricating metal cylinder is integrated with the piston rod. With this configuration, the shallow groove structure on the housing side can be obtained by processing a metal material having sufficient mechanical rigidity, such as high-tensile duralumin and stainless steel. On the other hand, in order to cope with the stroke of the piston rod, the length of the lubricating metal cylinder is increased.

  On the other hand, the metal cylinder material for lubrication can also be provided in the hydrostatic bearing part of the housing. FIG. 4 shows an example of the structure in that case. In the following, elements similar to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. Compared with FIG. 1, the piston drive mechanism 60 shown in FIG. 4 has the lubricating metal cylinders 68 and 69 not the piston rod 62 but the front end plate 64 and the rear end plate 66 of the housing 20. The difference is that it is provided integrally with the portion of the hydrostatic gas bearing 100.

  The lubricating metal cylinders 68 and 69 are cylindrical members, and the exhaust groove 42 and the surface throttle 46 are formed on the inner peripheral side, and are integrated with the front end plate 64 and the rear end plate 66 on the outer peripheral side. Fixed. The contents of the exhaust groove 42 and the surface stop 46 are the same as those described in relation to FIG. The material of the lubricating metal cylinders 68 and 69, the method of integration, and the like can be the same as the contents related to FIG.

  Thus, by providing the lubrication metal cylinders 68 and 69 in the housing 20, the lubrication metal cylinders 68 and 69 can be reduced in size. Referring to FIG. 2, if the symbols described there are used as they are, the lengths of the lubricating metal cylinders 68 and 69 can be {B− (A + 2S)} / 2. In the case of FIG. 1, the lengths of the lubricating metal cylinders 18 and 19 are {(B + 2S) −A} / 2, so that a shorter length is required. The piston rod 62 is preferably made harder than the lubricating metal cylinders 68 and 69 by surface treatment or the like.

It is a figure which shows the structure of the piston drive mechanism for tension compression test machines in which the static pressure gas bearing in embodiment which concerns on this invention is used. In embodiment which concerns on this invention, it is a figure explaining the required length of the metal cylinder material for lubrication. In embodiment which concerns on this invention, it is a figure explaining a mode that a piston rod and a metal cylinder for lubrication are integrated by shrinking or cooling. In an embodiment concerning the present invention, it is a figure explaining another way of providing a metal bearing for lubrication.

Explanation of symbols

  10, 60 Piston drive mechanism, 12, 62 Piston rod, 14 Flange part, 16 Load cell, 18, 19, 68, 69 Metal cylinder for lubrication, 20 Housing, 22 Cylinder tube, 24, 26, 64, 66 End plate, 30 Manifold, 34 Control gas flow path, 36, 38 Gas chamber, 40 Gas pressure control valve, 42 Exhaust groove, 46 Surface restriction, 48 Gas supply path, 50 Displacement sensor, 52 Open to atmosphere, 56 Stopper, 100 Hydrostatic gas bearing .

Claims (6)

In a static pressure gas bearing that supports the rectilinear axis of the piston drive mechanism in a levitating manner with respect to the housing
A static pressure gas bearing for a piston drive mechanism, comprising a metal cylinder for lubrication provided integrally with a linear shaft and having an outer peripheral surface serving as a gas receiving surface of the static pressure gas bearing. In a static pressure gas bearing that supports the rectilinear axis of the piston drive mechanism in a levitating manner with respect to the housing
A static pressure gas bearing for a piston drive mechanism, comprising: a metal cylinder for lubrication provided on a static pressure gas bearing portion of a housing and having an inner peripheral surface serving as a gas ejection surface of the static pressure gas bearing. In the static pressure gas bearing of the piston drive mechanism according to claim 1,
A static pressure gas bearing for a piston drive mechanism, wherein the lubricating metal cylindrical member is a cylindrical member integrated with a straight shaft by shrinking or cooling or bonding. In the static pressure gas bearing of the piston drive mechanism according to claim 1 or 2,
A static pressure gas bearing for a piston drive mechanism, wherein the lubricating metal cylinder is a copper-based metal cylinder. A straight axis connected to the piston,
A cylinder housing having a static pressure gas bearing that supports the piston linear axis so as to be linearly movable;
A metal cylinder for lubrication which is provided integrally with the piston linear shaft and whose outer peripheral surface is a gas receiving surface for the static pressure gas bearing;
A gas pressure actuator comprising: A straight axis connected to the piston,
A cylinder housing having a static pressure gas bearing that supports the piston linear axis so as to be linearly movable;
A metal cylinder for lubrication which is provided in a static pressure gas bearing portion of the cylinder housing and whose inner peripheral surface is a gas ejection surface of the static pressure gas bearing;
A gas pressure actuator comprising:

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