JP2763751B2 - Filter element and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter element used for a filter for removing foreign substances in a fluid and a method for manufacturing the same.

[0002]

2. Description of the Related Art Compressed air is supplied as a driving fluid to an air cylinder used for an actuator or the like of an industrial robot. In order to prevent a failure of the air cylinder or the like, it is desirable that clean and moisture-free compressed air be supplied to the air cylinder. For this reason, conventionally, dust, moisture, and the like in the compressed air are often removed by interposing an air filter between the air cylinder and the fluid supply means.

FIG. 6 illustrates a conventional air filter 21. The air filter 21 includes a hollow cylindrical filter element 22 and a cap 23 for closing a lower end surface of the filter element 22.
This filter element 22 has a two-layer structure. A sintered resin layer 24 such as polypropylene is disposed on the outer layer, and a cotton layer 25 is disposed on the inner layer.

[0004] Air is introduced into the air filter 21 configured as described above through an opening in the upper end face 22a.
The air that has reached the internal space of the air filter 21 passes through the cotton layer 25 and the sintered resin layer 24 in order, and then escapes from the entire outer peripheral surface to the outside (see arrow A1 in FIG. 6). Then, at that time, dust 26 and the like in the air are removed, and the air is purified. As shown conceptually in FIG. 7, the average size of the mesh of the cotton layer 25 (that is, the average size of the fiber gap) is determined by the average diameter of the continuous pores of the sintered resin layer 24. Is bigger than. Therefore, when air passes through the cotton layer 25, relatively large dust 26 is removed, and when air passes through the sintered resin layer 24, smaller dust 26 is removed. .

[0005]

However, in the case of the conventional filter element 22 having a two-layer structure, the air passage is sharply reduced at the interface 27 between the cotton layer 25 and the sintered resin layer 24. Dust 26 tends to collect in the vicinity of the interface 27 in particular. For this reason,
The filter element 22 is clogged at an early stage, and the pressure loss increases in a short time. Therefore, there is a disadvantage that the life of the filter element 22 is short.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a filter element having a long life because clogging of a specific portion hardly occurs and a method of manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided a filter element comprising a sintered body having fine continuous pores, wherein the continuous pores are formed of the sintered body. The gist is a filter element which is gradually reduced in size in a specific direction and has a more structured structure .

[0008] In the second aspect of the present invention, in the first aspect, the sintered body has a hollow cylindrical shape, and the continuous pores gradually become smaller from an inner peripheral surface to an outer peripheral surface of the sintered body. ing.

According to a third aspect of the present invention, in the second aspect, the sintered body is made of a resin powder, and a particle size of the resin powder is changed from an inner peripheral surface to an outer peripheral surface of the sintered body. It gradually gets smaller as you go.

According to the present invention, the sintered body has fine continuous pores, and the particle size of the resin powder constituting the sintered body is gradually reduced as it goes in a specific direction of the sintered body. In the method for manufacturing a filter element, a method for manufacturing a filter element, which includes sintering a molded body obtained by gradually filling the resin powder into the molding die while applying a centrifugal force to the molding die, is described. Make a summary.

According to the fifth aspect of the present invention, the sintered body is a hollow cylindrical sintered body having fine continuous pores, and the particle size of the resin powder constituting the sintered body is measured from the inner peripheral surface of the sintered body. In a method of manufacturing a filter element which is gradually reduced toward an outer peripheral surface, a molded body obtained by gradually filling the resin powder into the mold while rotating the mold about an axis of the mold. The gist of the present invention is a method for manufacturing a filter element for sintering.

[0012]

According to the first to third aspects of the present invention, the fluid is circulated along the direction in which the continuous pores gradually become smaller, thereby avoiding the accumulation of dust in a specific portion and reliably purifying the fluid. Can be achieved.

According to the second aspect of the present invention, the fluid flows from the inner peripheral surface to the outer peripheral surface of the sintered body,
The fluid can be surely cleaned while avoiding the accumulation of dust in the specific portion.

According to the fourth and fifth aspects of the present invention, when a centrifugal force is applied to the resin filled in the mold, the resin powder having a small particle size and the resin powder having a large particle size are regularly formed in the molded body. It becomes a state unevenly distributed. When the compact is sintered in such a state, a filter element is obtained in which the particle size of the resin powder gradually decreases as going in a specific direction of the sintered body.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied as a filter element in an air filter for an air cylinder will be described in detail with reference to FIGS.

As shown in FIGS. 1 and 2, the air filter 1 of the present embodiment has a hollow cylindrical resin sintered body S.
And a cap 3 for closing an opening in the lower end surface 2a of the filter element 2. The filter element 2 has a one-layer structure different from the conventional one.

The sintered body S has fine continuous pores through which air as a fluid can pass. In other words, fine gaps are present at the grain boundaries of the resin powder 4 constituting the sintered body S such that air can pass therethrough. The continuous pores in the sintered body S gradually decrease in a specific direction of the sintered body S. In the case of the present embodiment, the “specific direction” is a direction from the inner peripheral surface of the sintered body S to the outer peripheral surface. Similarly, the particle size of the resin powder 4 in the sintered body S gradually decreases from the inner peripheral surface to the outer peripheral surface of the sintered body S.

Next, one method of manufacturing the filter element 2 will be introduced. FIG. 3 shows a molding die 5 which constitutes a part of a manufacturing apparatus used when manufacturing the filter element 2. The molding die 5 includes a fixing portion 5a,
It consists of three parts, a rotating part 5b and a lid part 5c. A rotating part 5b is rotatably accommodated in the fixed part 5a of the molding die 5. A recess 6 having a shape corresponding to the outer shape of the filter element 2 is provided in the rotating portion 5b. A cylindrical core 8 for forming a through-hole 7 of the filter element 2 is provided at the center of the recess 6 so as to project therefrom. The lid 5c is provided on the upper surface of the molding die 5.
A rotating shaft 9 is connected to the center of the lower surface of the fixed portion 5a of the molding die 5. A gear 12 provided on the motor 11 side is engaged with a gear 10 provided integrally with the rotating shaft 9. Therefore, when the motor 11 is rotated, the rotating portion 5b rotates at a predetermined rotation speed following the rotation.

The formation of the molded body M is performed in the following procedure. First, the molding die 5 is driven by the driving of the motor 11.
Is rotated about its center line 13 as an axis.
In this state, the resin powder 4 as a molding material is gradually filled in the concave portion 6 of the rotating portion 5b. In this embodiment,
A mixed resin powder obtained by uniformly mixing a hard polypropylene resin having an average particle size of 100 μm and a polyethylene resin having the same average particle size is used. This mixed resin powder contains particles having a particle size of about 30 μm to about 150 μm. Here, when the filling is performed under the above conditions, the resin powder 4 having a smaller particle diameter moves to a position farther than the center line 13 (that is, near the inner wall surface of the concave portion 6). On the other hand, the resin powder 4 having a larger particle diameter tends to stop at a position closer to the center line 13. After the filling of the concave portion 6 with the powder resin 4 is completed, the lid 5 c is put on the upper surface of the molding die 5, and a pressing force is applied to the powder resin 4. Then, the molding material is held in a predetermined shape, and as a result, a cylindrical molded body M is obtained. In the case of the molded body M obtained in this example, the resin powder 4 of about 30 μm is unevenly distributed on the outer peripheral surface side, and the resin powder 4 of about 150 μm is unevenly distributed on the inner peripheral surface side.
The resin powder 4 of several tens μm is unevenly distributed in the middle. Then, if such a molded body M is fired in the molding die 5, the filter element 2 shown in FIGS. 1 and 2 can be obtained. Then, the obtained filter element 2 can remove drain of about 5 μm.

When the air filter 1 configured as described above is used, air is introduced from an opening in the upper end surface 2b which is not closed by the cap 3. The air that has reached the internal space 14 of the air filter 1 travels from the inner peripheral surface to the outer peripheral surface of the filter element 2 and finally escapes from the entire outer peripheral surface to the outside (see arrow A1 in FIGS. 1 and 2). . Then, at that time, dust and the like in the air are removed, and the air is purified. Here, in the case of the filter element 2 of the present embodiment, the continuous pores gradually decrease from the inner peripheral surface to the outer peripheral surface of the sintered body S as described above. That is, this filter element 2 includes:
There is no portion corresponding to the interface in the conventional filter element having a two-layer structure (that is, a portion where the size of the air passage is rapidly reduced). Therefore, dust does not stay intensively at a specific portion of the sintered body S. Therefore, premature clogging of the filter element 2 is eliminated, and the time required to reach a pressure loss is more reliably increased than before. Therefore, the life of the filter element 2 is longer than that of the related art.

Further, since the filter element 2 of this embodiment has a one-layer structure, the structure is simpler than that of a conventional product having a structure of two or more layers. Moreover, since the filter element 2 is made of only one kind of material, the filter element 2 is superior in strength as compared with the other case. Further, since the filter element 2 of the present embodiment is obtained by sintering the resin powder 4, it is excellent in lightness and cost. And if it is a manufacturing method using the above-mentioned molding die 5, etc., such an excellent filter element 2 can be manufactured easily and reliably.

The present invention can be modified, for example, as follows. (1) As in another example 1 shown in FIG. 4, the present invention can be embodied in a plate-like filter element 15, that is, in a non-hollow cylindrical shape. In the case of this filter element 15, the continuous pores gradually decrease in a specific direction of the sintered body S, that is, from the upper surface 15a to the lower surface 15b. Therefore, by circulating the air along the direction from the upper side surface 15a to the lower side surface 15b, it is possible to reliably purify the air while avoiding stagnation of dust in a specific portion. Of course, the present invention can be embodied in a shape other than the plate shape.

(2) As shown in another embodiment 2 shown in FIG. 5, the present invention can be embodied in a hollow cylindrical filter element 16 having a bottom. This filter element 16
In the case of, since the bottom portion 17 functions as the cap 13, the configuration can be further simplified than the configuration of the embodiment.

(3) The direction in which the continuous pores (particle diameter of the resin powder) decreases can be arbitrarily changed according to the use of the filter element. For example, in a cylindrical filter element, these may be reduced from one end face to the other end face. That is, the direction of the centrifugal force applied to the compact M during sintering can be arbitrarily changed.

(4) The sintered body S is not necessarily limited to a sintered body of the resin powder 4 as in the embodiment, but may be a sintered body of a metal powder or a ceramic powder. Good.

(5) On the upper end surface 2b of the sintered body S,
A mounting structure such as a male thread may be formed. With such a configuration, the air filter 1 can be easily attached.

(6) The compact M formed by the mold 5 may be fired while being held in the recess 6 of the mold 5, in which case the centrifugal force is generated by the rotation of the mold 5. May be given.

The technical terms used in this specification are defined as follows. "Sintered body: Not only a sintered body of resin but also a sintered body of metal and ceramics."

[0029]

As described in detail above, according to the first to third aspects of the present invention, since the continuous pores gradually become smaller in a specific direction, clogging does not easily occur in a specific portion. A long-life filter element can be provided. Also, because of the single layer structure, two or more layers
A filter element with a simpler configuration than the previous product
Can be provided.

According to the fourth and fifth aspects of the present invention, it is possible to provide a manufacturing method capable of easily and reliably obtaining the above-mentioned excellent filter element.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a filter element of an embodiment.

FIG. 2 is a schematic plan view of the filter element of FIG.

FIG. 3 is a schematic sectional view showing a method for manufacturing the filter element of FIG.

FIG. 4 is a schematic perspective view of a filter element of another example 1.

FIG. 5 is a schematic cross-sectional view of a filter element of another example 2.

FIG. 6 is a schematic sectional view of a conventional filter element.

FIG. 7 is an enlarged schematic view of the filter element of FIG. 6;

[Explanation of symbols]

2, 15, 16 ... filter element, 4 ... resin powder,
5: Mold, 13: Center line of molded body, S: Sintered body, M:
Molded body.

Claims (5)

(57) [Claims] 1. A filter element (2, 15, 16) comprising a sintered body (S) having fine continuous pores, wherein said continuous pores gradually decrease in a specific direction of said sintered body (S). And a more layered structure
In which the filter element. 2. The sintered body (S) according to claim 1, wherein said sintered body (S) has a hollow cylindrical shape, and said continuous pores are gradually reduced from an inner peripheral surface to an outer peripheral surface of said sintered body (S). Filter element as described. 3. The sintered body (S) is composed of a resin powder (4), and the particle size of the resin powder (4) is:
The filter element according to claim 2, wherein the size of the filter element gradually decreases from the inner peripheral surface to the outer peripheral surface of the sintered body (S). 4. A sintered body (S) having fine continuous pores, wherein a particle size of a resin powder (4) constituting the sintered body (S) is in a specific direction of the sintered body (S). The filter element (2, 15, 1
6) In the method of manufacturing, the molded body (M) obtained by gradually filling the resin powder (4) into the molding die (5) while applying centrifugal force to the molding die (5) is fired. A method for manufacturing a filter element to be tied. 5. A hollow cylindrical sintered body (S) having fine continuous pores, wherein the resin powder (4) constituting the sintered body (S) has a particle diameter of the sintered body (S). A method of manufacturing a filter element (2, 16), which is gradually reduced from the inner peripheral surface to the outer peripheral surface, wherein the molding die (5) is rotated around its center line (13) as an axis. (5) A method of manufacturing a filter element for sintering a compact (M) obtained by gradually filling the resin powder (4) therein.