JP2008221611A - Multi-layer plastic sintered body and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic sintered body having a desired filtering precision and a desired noise reducing effect without increasing pressure loss not so much, and further having an improved service lifetime. <P>SOLUTION: The sintered body is obtained by sintering a plastic powder in a mold and is formed into a multi-layer with individual layers formed by sintering plastic powders of different particle sizes. Because two or more layers having different sizes of void can be laminated, and the service lifetime of the plastic sintered body can be enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer plastic sintered body in which sintered bodies having different sizes of voids are laminated in multiple layers and a method for manufacturing the same.

  A plastic sintered body (plastic sintered porous body) is obtained by filling a plastic powder mold with a plastic powder having a predetermined particle size, and cooling it when the adjacent particles are fused together. It is a porous body having continuous voids (pores) and weaving a three-dimensional network structure.

  Since this continuous space | gap exhibits the function to which gas and a liquid move, this plastic sintered compact is used as a filter, a silencer, etc. However, conventionally, only a single plastic sintered body is known, and all commercially available plastic sintered bodies are single plastic sintered bodies.

  When this single-type plastic sintered body is used as a filter and a silencer, etc., it is necessary to use a sintered body having a small gap (hole) in order to obtain a desired filtration accuracy and a silencing effect. There was a drawback that the pressure loss was large. Therefore, this plastic sintered body is not so popular.

  The present invention has been made by paying attention to such points, and can obtain a desired filtration accuracy and a silencing effect, but a plastic sintered body having an improved service life without increasing pressure loss so much. The purpose is to provide.

  In order to achieve the above-mentioned object, the present inventor has conceived that, as a result of earnest research, the plastic sintered body is made into a multilayer having different gap sizes, and this multilayer plastic sintered body has not been conventionally performed. It has been found that it can be easily obtained by a multi-stage sintering method, and has reached the present invention.

  That is, the present invention is a sintered body obtained by sintering plastic powder in a mold, and the sintered body is formed in multiple layers by sintering each layer from plastic powders having different particle sizes. It is characterized by being.

  In this multilayer plastic sintered body, a sintered body obtained by sintering plastic powder in a molding die is placed in a molding die again together with a plastic powder having a particle size different from that of the plastic powder. It can be manufactured by tying.

  In order to manufacture a cylindrical multilayer sintered body, the first sintered body is formed into a cylindrical shape, and the molding die that forms the cylindrical space of the second sintered body on the outer periphery or inner periphery thereof is formed on the molding die. It is preferable that the first sintered body is housed and the cylindrical space of the second sintered body is filled with a plastic powder having a particle size different from that of the plastic powder and then sintered (Claim 3).

  In order to manufacture a plate-like multilayer sintered body, the first sintered body is formed into a plate shape, and the first mold is formed on a molding die that forms a plate-like space of the second sintered body on the upper surface thereof. It is preferable to sinter a sintered body and fill the plate-like space with plastic powder having a particle size different from that of the plastic powder.

  The multilayer plastic sintered body of the present invention is manufactured by laminating plastic powders having different particle sizes in a molding die through sheet-like or plate-like partition materials, and removing the partition materials after lamination and sintering. (Claim 5). By doing so, the multilayer plastic sintered body of the present invention can be obtained by one-time sintering.

  Since the present invention is a multilayer plastic sintered body having different gap sizes, a substance that becomes clogged can be held in the entire filter. As a result, the pressure loss can not be increased with a predetermined filtration accuracy, and the filtration life is significantly improved. Further, even when used as a sound deadening material, it is possible to maintain the predetermined sound deadening effect and not increase the pressure loss as much as the conventional one.

  Next, an embodiment of the present invention will be described.

  The 1st process of manufacturing the multilayer plastic sintered compact of this invention can be performed like the manufacturing method of a normal plastic sintered compact.

  For example, as shown in FIG. 1 (A), a lower mold 2 in which a round bar-shaped core 1 is erected in the center, and an upper mold in which a cylindrical cavity 3 is formed in the center as shown in FIG. 1 (B). 4, as shown in FIG. 1D, a molding die in which the core 1 is located at the center of the cavity 3 is assembled. Then, the cylindrical cavity 3 between the core 1 and the upper mold 4 is filled with plastic powder, and the upper end of the upper mold 4 is covered (not shown) and heated in the heating furnace before and after the melting point of the plastic powder. And sinter by heating for 20-30 minutes in a conventional manner. By this sintering molding, fine voids connected between the particles are formed.

  Then, when the molding die is taken out from the heating furnace and the upper die 4 is removed, a cylindrical plastic sintered body 5 fitted to the core 1 is obtained as shown in FIG. Before the sintered body is cooled to room temperature, an upper mold 4 ′ having a cylindrical cavity 3 ′ larger than the cavity 3 shown in FIG. The state shown in FIG. Next, a plastic powder having a particle size different from that of the plastic powder is filled in the ring-shaped cavity 3 ′ between the plastic sintered body 5 and the upper mold 4 ′. Then, the lid is covered in the same manner as in the first step, and sintering is performed for 20 to 30 minutes in a heating furnace heated around the melting point of the plastic powder. In this way, a plastic sintered body in which two layers having different gap sizes are integrated is obtained.

  By repeating the above steps, desired multilayer plastic sintered bodies such as three layers, four layers, etc. can be easily obtained. Whether to use two layers or three or more layers may be selected according to the purpose of use.

  As the material of the plastic powder used in the present invention, any material can be used as long as it is a material of this kind of plastic sintered body such as polyethylene, polypropylene, polystyrene, polymethyl methacrylate and the like. Moreover, although the material of each layer which forms a multilayer may be the same or different, generally it is preferable to use the same material in relation to heating temperature.

  The sintering temperature and time may be the same as in the past, but the sintering temperature is preferably at a temperature around the melting point of the plastic powder to be used.

  The particle size of the material of the plastic powder can vary widely depending on the number of layers to be laminated and the intended use of the sintered body, but is preferably 20 to 200 mesh (number of sieves per square inch). Good to do. These increase or decrease the particle size of the plastic powder forming the layer sequentially from the center toward the outside.

  The above shows an example in which the cylindrical body is laminated in the second step on the outer periphery of the cylindrical body manufactured in the first step. Conversely, the second step and the second step are sequentially performed on the inner periphery of the cylindrical body manufactured in the first step. Cylindrical bodies can be laminated in multiple layers in three steps. In that case, the size of the upper mold does not change, but it is only necessary to use molds having different core thicknesses as many as the number of layers to be formed.

  The multilayer sintered body of the present invention is not limited to a cylindrical shape, and may be a plate-shaped multilayer sintered body. In this case, one type of mold is used, the second plastic powder is filled on the upper surface of the sintered body sintered to a predetermined thickness from the mold bottom surface, and a plate-shaped lid is formed on the upper surface of the plastic powder. Then, the sintering in the second step may be performed.

  FIG. 2 shows another manufacturing method of the multilayer plastic sintered body of the present invention, and a cross-section disk is attached to a lower mold 2 ′ in which a round bar-shaped core 1 ′ is erected at the center shown in FIG. 2 (B). A jig provided with a cylindrical partition plate 7 shown in FIG. 2A for partitioning the cylindrical cavity 6 into two chambers having a disk-like cross section at the lower end of the disc-like lid 8 is mounted.

  A cylindrical partition plate 7 projects from the upper surface of the disc-shaped lid body 8, and a short cylindrical body 9 is erected on the outer periphery of the upper surface, and inside the cylindrical partition plate 7, the cylindrical partition plate 7 and the short cylindrical body. 9 and 9 are filled with plastic powders 10 and 11 having different particle sizes.

  Through holes (not shown) are respectively drilled in the disk-shaped lid body 8 on the bottom surface where the plastic powders 10 and 11 are taken, and the plastic powders 10 and 11 are filled into the cavity 6 through the through holes. Is done.

  Then, when the jig is pulled upward, the plastic powders 10 and 11 are filled into the cavity 6 of the lower mold 2 ′ as shown in FIG. 2 (C). This is covered as in the embodiment of FIG. 1 and sintered in a heating furnace heated before and after the melting point of the plastic powder. In this way, a plastic sintered body 12 in which the cross-sectional ring-shaped inner layer 10 ′ and the cross-sectional ring-shaped outer layer 11 ′ having different gap sizes are integrated is obtained.

It is a schematic perspective view which shows an example of the manufacturing method of the plastic multilayer sintered compact of this invention. It is a schematic sectional drawing which shows the other example of the manufacturing method of the plastic multilayer sintered compact of this invention.

Explanation of symbols

1, 1 '... Core 2, 2' ... Lower mold 3 ... Cavity 4 ... Upper mold 5, 12 ... Plastic sintered body 10, 11, ... Plastic powder

Claims (5)

It is a sintered body obtained by sintering plastic powder in a molding die, and the sintered body is formed in a multilayer in which each layer is formed by sintering from plastic powders having different particle sizes. A multilayer plastic sintered body that is characterized. A multilayer plastic characterized in that a sintered body obtained by sintering plastic powder in a molding die is again put into a molding die and sintered together with a plastic powder having a particle size different from that of the plastic powder. A method for producing a sintered body. The first sintered body is formed into a cylindrical shape, and the first sintered body is housed in a molding die that forms a cylindrical space of the second sintered body on the outer periphery or inner periphery thereof. The manufacturing method according to claim 2, wherein the cylindrical space of the sintered body is filled with a plastic powder having a particle size different from that of the plastic powder and sintered. The first sintered body is formed in a plate shape, and the first sintered body is mounted in a molding die that forms a plate-shaped space of the second sintered body on the upper surface thereof. The manufacturing method according to claim 2, wherein the plastic powder is packed and sintered with a plastic powder having a different particle size from the plastic powder. A method for producing a multilayer plastic sintered body, comprising: laminating plastic powders having different particle sizes in a molding die through a partition material; and removing the partition material after lamination and sintering.

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