JPS597762B2 - Method for manufacturing porous seamless pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a porous seamless pipe by extruding and sintering metal powder.

Conventionally, porous pipes have been made using metal powders such as copper powder, stainless steel powder, aluminum powder, etc., and have been made using (1) press forming method, (2) welding method, and (3) tap filling method (for example, U.S. Pat. No. 3,313,621). (see the book).

Among the above manufacturing methods, the press molding method involves adding a binder and other ingredients to the metal powder, kneading it, filling it into a press mold, and then compressing it with an appropriate pressure to create a pipe-shaped green compact. This is a method of manufacturing by sintering and straightening this.

The porosity C of the specimens taken from both ends of the pipe produced by this method is lower than that of the central part.

As a result, when this is used, for example, as a pipe for P material, the p excess efficiency in the axial direction becomes uneven.

Further, the press forming method has the disadvantage that it is difficult to manufacture long pipes, for example, pipes with a length/diameter ratio of 5 or more.

Next, in the welding method, a sheet-like green compact is made from a kneaded mixture of metal powder and a binder by roller molding, or in rare cases press molding, which is then sintered to an appropriate degree of depth, and then cylindrical with a pendent roller, press, etc. This is a manufacturing method in which the material is bent into a shape and the abutting surfaces are arc welded.

The variation in the porosity of each part of the pipe manufactured by this method is somewhat improved compared to the case using the press molding method, and long pipes can also be manufactured, but there is a drawback that the manufacturing cost is significantly higher.

In addition, in the tap filling method, synthetic resin-coated metal powder is charged into a tubular mold with a mandrel fixed in the center, the mold is vibrated to create the filled material, and the mold is heated at low humidity to form a mandrel. This is a manufacturing method in which the mold is removed after Takabuchi sintering, machined to ensure dimensional accuracy, and finally electrolytically etched.

This method has the disadvantage that it requires many manufacturing steps and the manufacturing cost is also high.

This invention aims to eliminate the drawbacks of the conventional method as described above, and its gist is to extrude and sinter a mixture of metal powder, binder lubricant, and water in a specific ratio. The purpose of the present invention is to manufacture a porous seamless pipe having a porosity within a predetermined range with small variations.

Extrusion methods suitable for carrying out the method of this invention include a ram extrusion method using a ram and a mandrel, and a screw extrusion method using an auger screw. Crosstalk, deaeration (
This method is suitable because it allows processes such as moisture adjustment) and extrusion molding to be carried out continuously.

In carrying out the method of this invention, we have determined through basic experiments the technical conditions that make it possible to manufacture porous, uniform-thickness seamless pipes that have a porosity within a predetermined range and have small variations in porosity.

In other words, bronze (PBC2, Sn
According to Table 1 showing the results of an extrusion molding experiment of a seamless pipe (outer diameter: 2Qmm, thickness: 2.57nm) using powder (Cu: 10%, balance Cu), bronze powder consisting of metal particle diameters within a predetermined range, For example, a mixture of a binder such as methyl cellulose, a binder filler such as granular halaffin, a lubricant such as glycerin or propylene glycol, and water as a solvent for the binder in a predetermined ratio is used as a screw. It was extruded and then sintered at 840°C.

Experiment A1 shown in the same table is an example in which 801 binders were mixed.

In this case, the binder alone is not sufficient to close the pores between the metal particles, and there are unoccluded pores, which causes dehydration and increases the extrusion resistance of the mixed material, making extrusion impossible. Met.

On the other hand, Experiment A2 differed from Experiment 51 only in that 751 caking filler was added to 801 caking agent, and the other conditions were the same, but the dehydration phenomenon did not occur and extrusion molding was possible. I yelled.

Next, Experiment A3 is an example in which a finer metal powder was used compared to Experiments A1 and A2.

In this case, extrusion molding was successfully carried out without adding a caking filler as in Experiment A2.

Regarding the extruded pipes of Experiments ▲2 and 3, the porosity after sintering determined by the above calculation formula was 35 to 45.

Next, we will introduce stainless steel (SUS316L), which is based on the JIS standard.
, C: 0.023%, Ni: 14.1%, Cr: 16.
Seamless pipe made of powder (9% Mo, 2.4% Mo, balance Fe) (outer diameter: 2 omm. Thickness: 2.5 m)
According to Table 2 showing the results of extrusion molding experiments (m), the above-mentioned binder, caking filler, lubricant, water, etc. are added to stainless steel powder consisting of metal particle diameters in a predetermined range in a predetermined amount. The kneaded product mixed in the same proportions was screw extruded and then sintered at 1300°C.

Experiment A4 shown in the same table is an example in which 1501 of the binder was mixed.

In this case, the binder alone is not sufficient to block the pores between the metal particles, and there are pores that are not blocked, which causes dehydration and increases the resistance to insert the mixed material, making extrusion molding difficult. It was impossible.

On the other hand, Experiment ▲5 differed from Experiment 54 only in that 75 P of caking filler was added to 150 g of caking agent, and the other conditions were the same, but the dehydration phenomenon did not occur and the extrusion Molding became possible.

Next, Experiments 56 and 7 are examples in which a finer metal powder was used compared to Experiments A4 and 5.

In this case, extrusion molding was successfully carried out without adding a caking filler as in Experiment A5.

Regarding the extruded pipes of Experiments ▲5, 6 and 7, the porosity after sintering determined by the above calculation formula was 33 to 38%.

From the above basic experiment results, in order to manufacture a porous seamless pipe by extrusion molding of metal powder, per 5 kg of metal powder, binder: 50-3001, lubricant: 50-250 cc.
It was found that it was necessary to prepare a mixture of 1 water and 500 to 1200 cc of water.

Note that the metal particle diameter is o. For metal powders of 1 mm or more, it is preferable to replace at least 25% of the binder with a binder filler, i.e. 13 g corresponding to 25% of the minimum mixing amount of 50 g of the binder, or 9 or more. .

Examples of the method of this invention will be described below.

That is, the SUS with a metal particle diameter of less than 0.04 mm
Using 316L stainless steel powder, a mixture was prepared by mixing 5 kg of the stainless steel powder with 110 g of the binder, 110 cc of the lubricant, and 700 cc of the water. Apply extrusion pressure to screw extrusion molding (outer diameter: 2Qmm, thickness:
2.5 meters, length: iooomm), then natural or Kabuchi (
Hot air) drying, then dewaxing heating and vacuum sintering (13
00℃×lh)L.

After that, correct the sintered density by swaging or using rollers. The furnace temperature according to ThJIS standard B8371 was measured, and the results are shown in Table 3.

In addition, the same table shows that the mixture was mixed in the same proportion as the above-mentioned interfering material, and press-molded (outer diameter: 2Q mvt, thickness: 2.5 ynm, length 10
077Xffl)L, then dried and sintered in the same manner as above.
The measurement results after correction are also listed.

According to the same table, the average value of the sintered density of extruded pipes is 5.
1 4 @/m3, and the difference (dispersion) between the maximum and minimum values is 0.18, while the average value of the sintered density of the press-formed pipe is 5.2 9 Vcritz The difference between the maximum and minimum values is 0.18. The difference (dispersion) is 1.03.

Therefore, it can be seen that the variation in sintered density of extruded pipes is smaller than that of press-formed pipes.

In addition, the average value of the porosity of the former is 35.0%, and the difference (dispersion) between the maximum and minimum values is 2.3, while that of the latter is 38.1%, with a dispersion of 13.1. It is.

Also, the variation in off-shore force is 0.6 μ for the former and 2.3 μ for the latter.
μ.

Therefore, extruded pipes have smaller variations in sintered density, porosity, and sintered density than press-formed pipes.
When used as a furnace material pipe, a certain degree of offshore efficiency can be guaranteed.

As described above, in the method for manufacturing porous seamless pipes by extruding and sintering metal powder, it is essential to optimize the mixing ratio of metal powder, binder, lubricant, and water, and this is within the specified range. It ensures a high porosity and has smaller variations than the conventional press forming method, and it is also possible to manufacture long pipes with a length/diameter ratio of 5 or more, which can be used as furnace material pipes for pneumatic or hydraulic filters, oil cleaners, etc. It has achieved remarkable technical results, such as a certain level of furnace efficiency when used as a heat pipe, and effective exhaust heat recovery when used as a heat pipe wick.

Claims (1)

[Claims] 1. Metal powder with a metal particle diameter of less than 0.117 Wffl, and a binder per 5 ky of this metal powder: 50 to 300
g. A porous seamless pipe characterized by manufacturing a mixture of polyhydric alcohol lubricant: 50 to 250 cc and water by extruding, sintering, and straightening processes. manufacturing method. 2. Metal powder with a metal particle size of 0.11 to 5 mm, and a binder of 50 to 300 g per 5 ky of this metal powder.
Caking filler: at least 13g, polyhydric alcohol lubricant 50~250cc, water: 500~1200cc mixed and kneaded, and then passed through an extrusion molding process, a sintering process, and a straightening process. A method for manufacturing a porous seamless pipe.