JPH03215604A - Method for manufacturing rods and tubes using powder as raw material - Google Patents

Abstract

PURPOSE:To easily manufacture a long hollow bar material having uniform composition by kneading fine powdery mixed raw material with binder, compacting, heating to remove the binder and at the same time, putting preliminary-sintered compact body into a metal capsule, degassing and executing hot extruding work after closely sealing. CONSTITUTION:The fine powder of metal, alloy, intermetallic compound, etc., having large sp. gr. and the fine powder of non-metal having small sp. gr., are mixed and the binder of paraffine, stearic acid, etc., is added and kneaded. The raw material is uniformly kneaded with large viscosity of the binder without separating the raw materials by difference of the sp. grs. After compacting this into cylindrical state, bar-state, etc., by heating, the binder is vaporized and removed and also the preliminary sintering is executed. The preliminary sintering bodies 11 - 14 are piled and charged into a steel-made capsule 10 or a double capsule 20, and after evacuating the inner part thereof, by executing sealing and the hot extruding work, the long pipe material or bar material is manufactured. By using the mixed raw material having large difference of sp. gr., the long member having uniform composition without any segregation of components can be manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing bars or tubes from metal powder or a mixed powder of metals and non-metals, and in particular, the invention relates to a method for manufacturing bars or tubes from metal powder or a mixed powder of metals and non-metals. A method that enables hot extrusion processing when it is difficult to mix uniformly due to differences in particle size and specific gravity, and it is difficult to directly fill metal capsules and perform hot extrusion processing. Regarding.

[Conventional technology]

Conventionally, methods for manufacturing rods or tubes from raw material powders such as metals include (a) a method in which the raw material powders are press-formed using a press mold and then sintered at high temperatures;

(0) Add a binder in which solids are dissolved in a solvent to the raw material powder, extrude the mixture at a temperature of 100°C or less, heat it to volatilize the solid content of the binder, and obtain a temporary sintered body. A method of sintering at high temperatures.

(c) A method of filling a metal capsule with raw material powder and hot extruding it into a billet.

etc. is known.

(Problem to be solved by the invention) The method (a) above relies on the ・T method or the press mold for the molded product, and therefore cannot obtain long rods or pipes. Not only that, but the pressure applied to the powder inside the press mold is not uniform. Further, in the method (0) using a binder, since the binder is used in an amount of 5 to 30% by volume of the two raw material powders, it takes a long time to remove the binder. In addition, the methods (a) and (0) above have low productivity because they are produced one product at a time.
Thin ones with a diameter of 20 to 30 mm or less have problems such as extremely poor productivity.

Next, the method (c) above is superior to the methods (a) and (g) in terms of product density, productivity, and product dimensional constraints, or if the powder is fine, pulverization, In the case of a mixture of two or more powders with different specific gravity and particle size, which are easily oxidized during processes such as mixing and capsule filling, it may be difficult to mix them uniformly, or even if the mixture is temporarily mixed, the There is a problem of separation during handling. As a countermeasure, is it possible to add paraffin or the like to the powder to isolate the powder particles from the air to prevent oxidation, or to properly bond the particles together to aid mixing and prevent separation? If filled, the added paraffin etc. cannot be completely removed, creating bores in the hot extruded material, and the alloy properties change depending on the carbon content, so it is not practical. Therefore, in conventional hot extrusion, only coarse powder having a particle size of 100 to 500 mm has been used, which does not cause the above-mentioned problems.

This invention is an attempt to solve the problems faced by each of the above-mentioned methods (a), (0), and (c).

(Means for Solving the Problems) In the present invention, as raw materials, metal powders such as simple metals, alloys, and intermetallic compounds, or non-metallic powders such as metal powders and metal compounds, nonmetallic elements, and nonmetallic element compounds are used. Use a powder mixture with metal powder.

The raw material powder described in F is mixed with a liquid binder. Examples of this liquid binder include substances that are liquid at room temperature such as petroleum and refined oil, substances that are solid at room temperature such as paraffin, stearic acid, resin, and camphor dissolved in volatile solvents, and paraffin. It is also possible to use heat-melted materials such as stearic acid, resin, and the like.

After this mixture of the binder and raw material powder is formed into a shape that almost fills a metal capsule, the binder is volatilized and the capsule is temporarily sintered. These treatments may be accomplished by heating, or the binder volatilization and temporary sintering may be performed in two stages, or both may be performed in one stage of heating.

The above-mentioned pre-sintered body is sealed in the above-mentioned metal capsule, and if necessary, the interior is deaerated and cold isostatically compressed according to a conventional method, and then hot extrusion processing is performed to obtain a product. .

If the size of the metal capsule is large and it takes a long time to volatilize the binder, the mixture of the raw material powder and the binder can be shaped into a short cylinder or a short cylinder with an outer diameter approximately equal to the inner diameter of the metal capsule. After molding, binder volatilization and temporary sintering are performed as described above, and a plurality of these are encapsulated in metal capsules in a stacked manner, and the pre-process and hot extrusion process are performed as described above to obtain a product.

In addition, the short cylindrical or short cylindrical temporary sintered body described above and the short cylindrical or short cylindrical solid metal material of the same diameter,
It is also possible to obtain a product by enclosing 8I layers alternately in a capsule and performing hot extrusion processing.

[Effect]

By adding a liquid binder to the raw material powder mentioned above, oxidation is prevented even when the particles are extremely fine and easily oxidized, and even when the powder is a mixed powder that easily separates due to differences in specific gravity and particle size, separation is prevented and molding is easy. become. Therefore,
This can be easily molded into a shape as close to the inner surface shape of the metal capsule as possible. The molded product maintains its strength by the bonding force of the binder while the binder is present, and maintains its strength by sintering after calcination, making it easy to handle. In this way, temporary sintering and hot extrusion can be carried out while effectively preventing the oxidation and separation movement of raw material powder particles that occur during the process, making it possible to efficiently produce long pipes and bars. It comes.

If the binder is present, it will create bores in the product and its carbon content will impair the alloy properties of the product, so it must be removed as completely as possible.

In FIG. 4, a curve 41 represents a cemented carbide (WC-25G).
To the mixed powder with an average particle size of 1.5 7L constituting o),
When 1.5% by weight of paraffin is added and formed into a cylindrical body with equal diameter and length, curve 42 shows the time required for the paraffin to completely volatilize by heating it to 350°C. , high-grade high-speed steel (10w-: lMo-
4Cr-10V-10TiN-3C (remaining Fe) with an average particle size of 1.8 IL■, the 3.0
When a similar cylindrical body is molded with the addition of % by weight of paraffin, the time required for the paraffin to completely volatilize by heating to 350°C is shown.

According to this, in the case of curve 41 (cemented carbide), the diameter is 10
0mm. It takes 13 hours for a length of 100■■ and a curve of 42
(high-grade high-speed steel): diameter 70ms, length 70■■
This takes 15 hours, which is the practical limit, and anything larger than that is extremely disadvantageous in practice. If the diameter is 2001 cm and the length is 200 cm, the curve 4l will require 38 hours, which makes it less practical. Therefore, due to the relationship between the billet diameter and the extrusion port diameter in hot extrusion processing, if it is necessary that the capsule inner diameter is 150 μl or more, the binder can be easily removed by shortening the capsule length. As a result, the length of the product is limited, the processing yield deteriorates, and productivity decreases.

However, when the molded body of the binder and raw material powder is in the shape of a short cylinder or short cylinder, the binder can be completely removed within a short time regardless of the outer diameter. For example, the raw material shown by curve 41 in Figure 4 (particle size 1.5 cm)
The time required for volatilization of paraffin at 350° C. for cemented carbide blended powder with 1.5% by weight of paraffin added is shown in curves 51, 52, 53, and 54 shown in FIG. To give a specific example, the time required to remove paraffin by heating a cylindrical body with a diameter of 200°C to 350°C is 38 hours as mentioned above if the length is 200°C, If the length is halved to 1001, it will be shortened to 12 hours, making it more practical, and if the length is further halved, to 50 seconds, it will be an extremely short time of 4.5 hours. Therefore, by stacking a large number of short pre-sintered bodies and accommodating them in a capsule, it is possible to shorten the time required to remove the binder and increase production efficiency, and at the same time, it is possible to eliminate the dimensional limitations of extruded billets. I can do it. The use of large dimensions as extruded billets is
This not only makes it possible to manufacture large-diameter products, but also increases the length of the extrudate, thereby reducing the ratio of defective parts at both ends, resulting in an effect of improving product yield.

In addition, when hot extrusion processing is carried out on a capsule in which short pre-sintered bodies and short solid metal materials are stacked alternately, the parts transferred from the pre-sintered bodies and the solid metal materials are separated. It is also possible to obtain a bar or tube in which the sections are joined alternately in the longitudinal direction. In this case, the strength of the joint between the two parts is much greater than that of friction welding, welding, brazing, etc. because there are no foreign substances or cast structures present at the joint interface.

(Example) Example 1 High speed alloy steel (10$W - 3% No - 4$C
r-10$V - 10%Go - 10$TiN -
Paraffin in an amount equivalent to 3% by weight was added to 4 layers of mixed fine powder with an average particle size of 1.8, which was blended so as to constitute 3C and the remaining Fe (in other words, weight%). A cylindrical molded body with a diameter of 100 mm and a length of ISO mm was produced by pressing. This was heated at 350°C in a hydrogen atmosphere furnace.
Heat for 30 hours to volatilize the paraffin, then heat at 85
The mixture was heated at 0°C for 1 hour to obtain a temporary sintered body. The internal dimensions of this temporary sintered body are 1021 mm in diameter, 152 mm in length, and 4 mm in thickness.
It was placed in an ordinary steel capsule (■) and sealed with sufficient inspiration. The capsules were heated to 1100°C by induction heating, loaded into a hot extruder, and extruded into a rod shape with a diameter of 26 ms. Comparative materials were obtained by processing using the conventional method of horizontal compression.

Table 1 shows the results of measuring the mechanical properties of these hot extruded materials and comparative materials after heat treatment under the following conditions.

Heat treatment conditions: Quenching at 1220°C for 3 minutes → Oil quenching and tempering at 560°C for 90 minutes → Air cooling 3 times Ta.

Example 2 WC powder with an average particle size of 1.5 Bs and an average particle size of 1.2 g
m of CO powder at a ratio of 75:25 (wt%) and mixed by ball milling, and then a solution in which paraffin in an amount equivalent to 1.5 wt% of the amount dissolved in a solvent was added and mixed. Then, the average particle size was reduced to 100IL using a spray dryer.
Granulated powder (2) was obtained. This is made with a hydraulic press to a diameter of 100 mm.
■The intestine was molded into a cylindrical shape with a length of 150■■, heated in a vacuum furnace at 350°C for 15 hours to remove paraffin, and then heated at 1000°C for 1 hour to form a pre-sintered body. I got it. This pre-sintered body was placed in a rotating capsule as in Example 1,
After degassing and sealing, this capsule was heated to 1250° C. and immediately loaded into a hot extruder to hot extrude it into a round bar with a diameter of 401 layers.

On the other hand, the same raw material powder was processed by the conventional method of press molding and paraffin sintering to obtain a comparative material.

Table 2 shows the results of measuring the mechanical properties of these hot extruded materials and comparative materials.

Table 2 The hot extruded material listed in F had a uniform composition throughout the sample, and had a dense structure with no voids made of fine particles.

Example 3 Paraffin in an amount equivalent to 3% by weight was added to the same raw material powder as in Example 1, and a diameter of 100 cm was added using a hydraulic press.
■, Formed into a cylindrical shape with an inner diameter of 50 mm and a width of 150 mm, heated in a hydrogen atmosphere furnace at 350°C for 12 hours to remove paraffin, and then heated at 850°C for 1 hour. A temporary sintered body was obtained.This temporary sintered body was made into an outer tube with an inner diameter of 102 mm, a length of 152 mm, and a thickness of 4 mm, an inner tube with an outer diameter of 48 mm, a length of 152 mm, and a thickness of 4 mm. The capsule was placed in a double cylindrical capsule made of ordinary steel with a thickness of 2■■, degassed and sealed, and then heated to 1100°C and processed using a hot extruder to obtain an outer diameter of 55mm. This hot extruded material had no problems in appearance, and its mechanical properties were almost the same as the hot extruded round bars shown in Table 1.

Example 4 Paraffin was dissolved in a solvent and added to a mixed raw material fine powder having the composition and average particle size shown in Table 3, press-molded into the shape and dimensions shown in the same table, and heated to 85°C. After the solvent was evaporated, it was heated to 350°C to evaporate the paraffin. The time required for volatilization of paraffin is shown in the same table. Table 3 These molded bodies from which paraffin has been removed are iooo°C
These pre-sintered bodies II.
In Examples 1.2, 3, and 5, the cylindrical capsules 1o shown in FIG. shaped capsule 20
The inside was sealed with air. capsule 10, 2
0 is made of ordinary steel and has an outer diameter of 170mm. Inner diameter Islms
, External length 240 mm, Inner length 201 mm Te, Inner cylinder 21 of capsule 20 has an outer diameter of 49 layers and an inner diameter of 3
There are o ■ layers. The sealed capsules were heated to the temperature shown in Table 4, which was made into a billet and hot extruded, and the ordinary steel portion was removed by machining to obtain a product with the dimensions shown in the table. Preliminary sintered body 11 of each product. The properties of the parts that were inside 12, 13, and 14 and the part that corresponds to the boundary of the temporary sintered body were
It is shown in the table. Table 4: When the above-mentioned product was observed under a microscope, no holes were found in any part of the product. In addition, by using a long capsule 3o as shown in FIG. 3, a large number of temporary sintered bodies 11
．． When hot extrusion processing is performed with 12...1N contained, the proportion of defective parts occurring at both ends of the extrudate is reduced, and the product yield is greatly improved.

Example 5 Paraffin was added to the same mixed powder raw material of high-speed alloy steel as in Example 1, and the mixture was formed into a cylindrical shape with a diameter of 100 m and a length of 90 m using a hydraulic press, and heated at 350°C for 23 hours. The paraffin was removed by heating, and the mixture was heated at 850°C for 1 hour to obtain a temporary sintered body. These 5 temporary sintered bodies and 1 diameter
00mm. S K processed into a cylindrical shape with a length of 68 s
D 61 steel 6 pieces, inner diameter 102■■, length 870■
The samples were alternately housed in ordinary steel capsules with a thickness of 5 cm, thoroughly deaerated and sealed. If this capsule is heated by induction heating,
(1) A rod heated to 1°C and extruded into a rod shape with a diameter of 50 mm by hot extrusion, and a rod made of a high-speed alloy steel part of about 250mm long and an SKD61 steel part of about 2701mm length. This bar material was cut at the center of each material, and the length of the high speed alloy steel section was approximately 125mm, S
A material for an end mill with a thickness of about 135 layers, which is the length of the κD61 steel part, was obtained.

The thickness of each of the three parts of the material for this entomill is 4mm
, a width of 811 and a length of 25 ms were cut out, each was heat treated under the same conditions as in Example 1, and the mechanical properties were measured. Table 5 shows the results.

Table 5 Note that in the transverse rupture strength test, the test piece at the joint did not break at the joint interface, but at the high-speed alloy portion beside it.

Other than that, satisfactory test results were obtained for both the high speed alloy steel section and the SKD61 steel section.

Using the above-mentioned entomill material, the blade portion 6I shown in FIG.
The handle 62 was processed and heat treated under the same conditions as shown in Example 1 to produce an end mill. Blade part 61
is made of high-speed alloy steel, has a blade length of 120 mm, and has 6 blades. Also, most of the handle 62 is S K D 6
1 steel, maximum diameter 42+*m, length 1:l [l
mm, and close to the blade part 51 high speed alloy steel and SK
There is a bonding interface 63 of D61 steel.

10 such end mills were manufactured and tested for cutting SSSC steel materials, and no breakage occurred.

Example 6 Paraffin was added to the same high-speed alloy steel mixed fine powder raw material as in Example 1, and the diameter was 100 mm and the length was 110 mm.
(2) It was press-molded and heated at 1350°C for 27 hours to remove paraffin, and then heated at 850°C for 1 hour to obtain a temporary sintered body. Apart from this, the diameter of 100m+s. lsa48-
SKD61 steel material of s was prepared. A capsule made of ordinary steel with an inner diameter of 102 sm, a length of 280 mm, and a wall thickness of 5 m.
The two temporary sintered bodies described above were stacked and housed, and the steel material L was housed in the -L, which was degassed for 7 minutes and sealed. This was heated to 1100° C. by induction heating and processed into a bar with a diameter of 42 cm by hot extrusion. This bar has a length of high speed alloy steel section or approximately 900-1. The length of the SKD61 steel part is approximately 270■■
There was.

Using the above extruded bar material, as shown in Fig. 7, the length is 895 mm.
A screw portion 7L of (1) and a shaft portion 72 of 270 mm in length were processed and heat treated under the same conditions as shown in Example 1 to produce an injection molding screw. In addition, 7
3 shows the joint interface between the high speed alloy steel part and the SKD51 steel part.

This injection molding screw is currently undergoing operational testing or is operating without any problems.

〔Effect of the invention〕

As is clear from the examples in L below, the use of a binder in accordance with the present invention makes it possible to handle fine raw material powders that are easily oxidized, raw material powders that are difficult to mix uniformly due to differences in particle size and specific gravity, and By using raw material powders that are easily separated during handling due to differences in density and specific gravity, it is possible to efficiently produce rods and tubes that are homogeneous, dense, and have excellent mechanical properties by hot extrusion processing. Moreover, hot extrusion process-L
The binder can be completely removed in a short time prior to hot extrusion even if the size of the billet used for the process increases, so it is unprecedented to eliminate the negative effects of residual binder on the product and reduce the time required to remove the binder. can increase production efficiency. Furthermore, since a large-sized extruded billet can be used, not only a large-diameter product can be obtained, but also the product yield can be improved.

[Brief explanation of drawings]

The figures show a billet for hot extrusion in an embodiment of the present invention, FIG. 1 is a longitudinal cross-sectional view of a billet for producing a bar material, FIG. 2 is a longitudinal cross-sectional view of a billet for producing a pipe material,
Figure 3 is a longitudinal cross-sectional view of a billet for producing long bars, Figure 4 is a diagram showing the relationship between the diameter of a molded product of similar shape and the time required to remove baraffin, and Figure 5 is the same. A diagram showing the relationship between the length of the diameter of the molded object and the time required to remove paraffin,
FIG. 6 is a side view showing an example of a product according to an embodiment of the present invention, and FIG. 7 ['J is a side view showing an example of a product according to another embodiment of the invention. 10, 20 and 30...metal capsule, 11~IN
...Preliminary sintered body of raw material powder. Figure 1 Figure 3 Figure (mm) { (n

Claims (3)

[Claims] (1) Adding a binder to a metal powder or a mixed powder of metals and non-metals, molding it into a shape that almost fills a metal capsule, volatilizing the binder from the molded product by heating, and pre-sintering it; A method for producing a rod or pipe material using powder as a raw material, characterized in that this pre-sintered body is housed in the metal capsule and subjected to hot extrusion processing. (2) Add a binder to metal powder or mixed powder of metal and non-metal, mold it into a short cylinder or short cylinder with an outer diameter approximately equal to the inner diameter of the metal capsule, and remove the binder from this molded product by heating. 1. A method for producing a rod or pipe material using powder as a raw material, characterized in that the powder is volatilized and pre-sintered, and a plurality of the pre-sintered bodies are stacked and housed in the metal capsule and subjected to hot extrusion processing. (3) Add a binder to metal powder or a mixed powder of metals and non-metals, mold this into a short cylinder or short cylinder with an outer diameter approximately equal to the inner diameter of the metal capsule, and remove the binder from this molded product by heating. This is volatilized and pre-sintered, and the pre-sintered body and a short cylindrical or short cylindrical solid metal material having an outer diameter approximately equal to the inner diameter of the metal capsule are alternately stacked and housed in the metal capsule. 1. A method for producing rods and pipes using powder as a raw material, characterized by subjecting the powder to hot extrusion processing.