KR200326537Y1 - Air bearing with a porous material - Google Patents

Abstract

The present invention relates to an externally pressurized porous static pressure air bearing. More specifically, the vent air supply hole is formed by inserting and fixing a vent, a material in which a plurality of minute air supply holes are formed on a bearing surface supporting a load, by shrinking or pressing. The present invention relates to a static pressure air bearing using a porous material which eliminates friction generated between the bearing surface and the journal of the shaft by the air injected through and greatly improves the rigidity and the load capacity (load support capacity).

The porous material vent is manufactured through a sintering process, and serves as an injection hole for injecting air to the bearing surface through fine air supply holes having a uniform diameter.

As such, the air bearing using the porous material according to the present invention not only has superior stiffness and load capacity as compared to the conventional air bearings, and almost no friction occurs, and heat generation hardly occurs at high speed and low temperature. It can be used, and the rotational accuracy is very high. In addition, even during start and stop, direct metal contact between the shaft and the bearing can be avoided, so that vibration and noise are hardly generated, and abrasion is hardly generated, thereby achieving a nearly permanent life.

And since it uses air as a working fluid, it can be easily applied to food machinery or semiconductor equipment that requires clean without contamination by oil, and it uses a porous material that is easy to be inserted into a bearing body with a spray hole. There is an advantage that is easy to apply.

Description

Constant pressure air bearing using porous material {Air bearing with a porous material}

The present invention relates to an externally pressurized porous static pressure air bearing. More specifically, the vent air supply hole is formed by inserting and fixing a vent, a material in which a plurality of minute air supply holes are formed on a bearing surface supporting a load, by shrinking or pressing. The present invention relates to a static pressure air bearing using a porous material which eliminates friction generated between the bearing surface and the journal of the shaft by the air injected through and greatly improves the rigidity and the load capacity (load support capacity).

In general, the bearing is a mechanical element that serves to reduce the frictional resistance while transmitting the load. The typical structure of such a bearing is a rolling bearing using rolling motion of rolling elements such as balls or rollers, which are high in noise, weak in impact, large in outer diameter, and rotational speed due to rolling effect of rolling elements in rotational motion. The disadvantage is that the limit is low. In order to overcome these disadvantages, a sliding bearing is used that forms a thin oil film between the bearing and the shaft and generates pressure in the oil film to support the load by the force of the pressure. Such sliding bearings are classified into oil bearings and air bearings according to the type of fluid used. Oil bearings are called incompressible fluid lubrication bearings because they use oil or water such as mineral oil as the working fluid and there is almost no change in volume even if the pressure changes. However, since these oil bearings mainly use oil as a working fluid, they are difficult to use in food machinery or semiconductor equipment requiring cleanliness.

Air bearing, another form of fluid bearing, uses air, helium, and neon gas as its working fluid, so it has little friction, and it has a cooling effect, so it generates little heat during high speed movement, so it can be used at high and low temperatures. In addition, the roundness error inevitably generated during the machining of the bearing is reduced by 1/10 or less compared to the roundness error due to the compressibility of air, resulting in a very high rotational precision. In addition, even when starting and stopping, direct metal contact between the shaft and the bearing can be avoided, so vibration and noise are hardly generated, and abrasion is hardly generated. Because load bearing capacity is slightly lower than ball bearings or oil bearings, it is not suitable for heavy loads.

Types of the injection port of the above-mentioned constant pressure air bearings include an orifice type shown in FIG. 1, a slot type shown in FIG. 2, a surface resistance type (groove type) shown in FIG. 3, an orifice-pocket type shown in FIG. 4, and the like.

First, looking at the injection port 11 of the orifice-type static pressure air bearing shown in Figure 1, the air is supplied through a wide air supply hole (11a) formed in the bearing 10 is about 0.1 ~ 0.3 mm in diameter near the bearing surface, The length is such that air is supplied to the bearing surface through the small air supply hole 11b of 1 mm-2 mm or less. The method for processing the orifice-type injection hole 11 as described above is to form a wide air supply hole (11a) by a drill from the outside of the bearing (10) first, and then electric discharge machining (super drill processing at about 1 mm to 2 mm from the bearing surface). ) To form a small air supply hole 11b. However, since the orifice-type injection holes 11 require 24 pieces per bearing and up to 200 pieces in many cases, the cost and time for processing the injection holes are enormous, and the diameter of the air supply hole 11b is 0.1 mm or less. Since it is difficult to machine, it is difficult to generate a uniform pressure because the diameter of the air supply hole (11b) is different, respectively.

Next, a detailed view of the injection port of the slot-type static pressure air bearing 20 shown in Figure 2, the inlet is a bearing having a shape in which the slot 21 formed in the vicinity of the wide and close to the bearing surface continuously arranged in the circumferential direction, It is a bearing in a similar manner to the orifice type injection port 11 described above.

The injection hole 31 of the surface resistance type (groove type) constant pressure air bearing 30 shown in FIG. 3 has a large area in such a manner that the air supplied through the groove 31a formed very shallowly on the bearing surface causes a pressure drop. It is a constant pressure air bearing that can generate pressure in the air. However, in the groove-type static pressure air bearing, there is a groove 31a having a space that can contain some air, such as a pocket, and the compressed air accumulated in the space escapes and expels the shaft A by the impact. Air hammering phenomenon, which is an internal phenomenon, occurs and there is a problem that continuous vibration occurs even when there is no load from the outside. Therefore, considerable care is required in design and manufacture.

Finally, the injection port 41 of the orifice-pocket type static pressure air bearing 40 in which the orifice type and the pocket type shown in FIG. 4 are described, the above-mentioned multiple air supply type (orifice type) and surface resistance type (groove type) ), A deep pocket 42b is provided in the lower portion of the orifice-type air supply hole 41a so as to generate pressure in a large area with less air supply holes. However, the orifice-pocket type static pressure air bearing also has a problem in that the above-mentioned air hammering phenomenon occurs and, like the orifice-type injection port 11 of FIG. 1, problems in manufacturing and cost and time are required.

As described above, in the conventional positive pressure air bearing, how to inject air to generate a uniform pressure is the most important problem, and various types of nozzles have been developed to solve this problem, but the diameter of the air supply holes is uniform and fine. It has been difficult to make full use of the advantages of hydrostatic air bearings until now.

In addition, due to the above reasons, in order to have a large load bearing capacity using the static pressure air bearing, the size of the whole bearing system must be large, and there is a problem that it is difficult to apply to the part requiring high rigidity. In addition, since the recent industrial development is demanding a miniaturized, lightweight machine with high speed, high precision and high load capability, the conventional static pressure air bearing with a nozzle does not satisfy the demand.

The main object of the present invention for solving the above problems is a method of inserting and fixing a vent which is a porous material having a plurality of uniform fine air holes in the bearing body without machining the injection hole of the bearing formed in the bearing body by machining. It is possible to simplify the installation of the air bearing nozzle, and to provide a constant pressure air bearing using a porous material that can greatly increase the load carrying capacity and rigidity of the bearing with only a small amount of air injected through the vent air supply hole. have.

1 is a view showing a conventional orifice type injection hole,

2 is a view showing a conventional slotted nozzle;

3 is a view showing a conventional surface resistance type (groove type) injection hole,

4 is a view showing a conventional orifice-pocket type injection hole,

5 is a view showing the structure of a vent, a porous material according to the present invention,

6 is a photomicrograph of a 60 times magnification of the air supply surface of the porous vent according to the present invention,

7 is a photograph of a slider bearing in which a conventional orifice type injection hole is processed on a bearing surface;

8 is a photograph of the slider bearing is inserted and fixed porous vent according to the present invention,

9 is a view illustrating the press-fit of the porous vent into the bearing body using a vise,

10 is a view showing a journal bearing in which a porous vent is inserted according to the present invention;

11 is a view showing a thrust bearing in which a porous vent is inserted according to the present invention;

12 is a view showing a journal-thrust bearing in which a porous vent is inserted according to the present invention.

Explanation of symbols on the main parts of the drawings

10: orifice type constant pressure air bearing 11: orifice type injection port

20: slot type constant pressure air bearing 21: slot type nozzle

30: surface resistance type (groove type) constant pressure air bearing 31: groove type injection port

40: orifice-pocket type static pressure air bearing 41b: pocket of the injection port

50: porous vent 51: air inlet of the porous vent

A: Axis B: Vise

As a means for achieving the above object, the configuration of the constant pressure air bearing using the porous material according to the present invention, the bearing body; Holes formed in the bearing body by drilling or milling; Inserted and fixed in the hole of the bearing body is made of a vent, a porous material formed hundreds of air supply holes having a diameter of 0.03 mm or less to serve as the injection hole.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that the present invention can be easily implemented by those skilled in the art.

Looking at Figure 5 showing an embodiment of the porous material vent acting as the injection port of the air bearing, the structure of the vent 50 used as the porous material is a cylindrical tube form, the overall length 10mm, outer diameter 6mm 880 uniform supply holes 51 having a diameter of 4 mm of the portion where the air supply holes 51 are distributed, an effective diameter of 3.5 mm and a diameter of 0.003 mm of the portion where the air supply 51 is distributed are in contact with the bearing surface. It is distributed within the effective diameter.

The shape and dimensions of the vent 50 used as the porous material is just one embodiment, and may be manufactured in various shapes and dimensions according to the type and specification of the bearing.

FIG. 6 shows a 60 times magnified image of the air supply 51 surface of the porous vent 50 under a microscope, and foreign matter attached to the air supply 51 surface is removed through a washing process.

The porous vent 50 is used as a passage of air to be sprayed on the bearing surface in the same manner as the conventional orifice type, slot type, groove type, orifice-pocket type nozzle. However, looking at the performance test results presented in the following table, it can be seen that the performance of the static pressure air bearing using the porous vents is significantly improved.

division Nozzles / Vents (pcs) Supply air diameter (mm) Air supply pressure (㎏f / ㎠) Flow rate consumption (L / min) Allowable load (㎏) Floating height (mm) Conventional Orifice Type Air Bearings 24-200 0.1 to 0.3 5 atmospheres 36 48 0.051 Porous Vent Air Bearings 6-20 0.0028 ~ 0.03 5 atmospheres 25 120 or more 0.095

As shown in the above table, when the porous vent 50 is used, the amount of air consumed under the same air supply pressure (5 kgf / cm 2) is 25 L / min, which is reduced to 2/3 of the conventional orifice type, but the maximum allowable load The 120kg will increase three to four times. In addition, the number of injection holes formed in the bearing body is significantly reduced, and the conventional orifice-type injection hole 11 shown in FIG. 7 is processed on the bearing surface of the slider bearing and the porous vent which is the first embodiment according to the present invention shown in FIG. 8. This can be seen by comparing the slider bearings to which 50 is inserted and fixed. And, as can be seen in Figure 7, the orifice-type injection hole (11) applied to the conventional slider bearings are irregular in diameter and dozens of numbers, and difficult to use due to mistakes, the machining must be reworked There is a problem. However, as shown in FIG. 8, in the case of an air bearing using the vent 50, which is a porous material according to the present invention, only a few porous vents 50 are inserted into and fixed to a bearing body, thereby improving performance much more than conventional air bearings. You will get

The porous vent 50 is manufactured by the sintering method is as follows.

First, raw materials and additives are selected according to the type of bearing to be used and the performance required by the bearing, mixed with a lubricant in a mixer, and mixed in a mold manufactured precisely in the same shape as the external shape of the porous vent to be used for the constant pressure air bearing. The powder is filled, and fine wire is infiltrated into the portion where the air supply holes of the porous vent are to be formed, and then pressed to obtain a molded body having a desired shape and density.

Then, the molded body is heated to a temperature below the melting point of the material in a protective atmosphere so that the porous vent has the required properties. At this time, the wire inserted in the previous step is completely incinerated so that the space occupied by the wire is filled with air It will be.

Thereafter, the sintered compact is pressed into a precise mold during repressurization to increase the degree of the porous vent to complete the porous vent.

In addition to the above main process, an auxiliary process such as heat treatment, washing, impregnation, deburring, and surface treatment may be added.

As such, the air supply hole 51 of the porous vent is determined by the diameter of the wire used in the sintering process, and the air supply hole is also uniform since the diameter of the wire used is uniform.

Next, a method of inserting and fixing a vent, a porous material manufactured as described above, into the body of the bearing will be described.

The first method uses shrinkage, which is used in industries where strength and precision are more demanding than any other fitting method, and shrinkage tolerances are very precise, ranging from 1 / 1,000 to 15 / 10,000 mm of shaft diameter. . First, drill a hole about 0.1 mm smaller than the outside diameter of the porous vent in the journal, thrust, and planar slide bearing body, heat the bearing body to about 200 ° C., and accurately insert and fix the cooled and shrinked porous vent when the inner diameter is sufficiently enlarged. After that, as the temperature of the bearing body decreases over time, the porous vent and the bearing body are tightly coupled.

The second method is press-fitting. Drill a hole 0.1 mm smaller than the outside diameter of the porous vent in the bearing body, and taper the end of the porous vent slightly smaller than the hole diameter of the bearing body, and then press the porous vent with a hydraulic or precision vice. Press to force the insertion into the hole of the bearing body. 9 shows that the porous vent 50 is pressed into the bearing body C using the vise B. Referring to FIG.

10, 11 and 12 are views showing that the above-described porous vent is inserted and fixed in various types of static air bearings.

10 is a photograph showing a journal bearing in which a porous vent is inserted according to a second embodiment of the present invention, and a porous vent 50 is inserted and fixed to a bearing surface supporting a rotational movement of the shaft.

11 is a photograph showing a thrust bearing having a porous vent inserted therein according to another embodiment of the present invention, and a porous vent 50 is inserted and fixed to a bearing surface supporting an axial load.

FIG. 12 is a view showing another embodiment of the present invention, in which a porous vent-inserted journal thrust bearing is mounted. The porous vent 50 is disposed on a bearing surface supporting an axial rotation and a bearing surface supporting an axial load. Insertion is fixed.

Herein, while the present invention has been described with reference to the preferred embodiments, those skilled in the art can variously modify and apply the present invention without departing from the spirit and scope of the present invention described in the claims. This will be possible.

As discussed in the above embodiment, the present invention uses a vent, a porous material having hundreds of fine air supply holes of uniform size, as the air bearing nozzle, thereby greatly increasing the load bearing capacity and rigidity of the bearing compared to the conventional air bearing. It works.

In addition, there is little friction, there is a cooling effect hardly generates heat during high-speed movement can be used at high temperatures and low temperatures, the rotational accuracy is very high effect. In addition, even when starting and stopping, direct metal contact between the shaft and the bearing can be avoided, so that vibration and noise are hardly generated, and almost no wear occurs, thereby achieving a nearly permanent life.

And since it uses air as a working fluid, it can be easily applied to food machinery or semiconductor equipment that requires clean because there is no contamination by oil, and it uses a vent which is a porous material that is easy to be inserted into a bearing body with a nozzle. It also has the advantage of being easy to apply to bearings.

Claims (4)

In constant pressure air bearings, One side has a clogged tubular shape, and one side of the clogged portion is inserted into a vent 50 having a myriad of air supply holes 51 having a diameter of 0.03 to 0.003 mm into the body of the bearing and used as an air inlet. Constant pressure air bearing using a porous material characterized in that. The method of claim 1, The air supply hole 51 formed in the vent 50 is a space formed when the wire is completely incinerated when the fine wire is pre-soaked after heating in a blocked portion of the vent when the vent 50 is manufactured. Positive pressure air bearings using materials. delete delete