JPS605806A - Production of sintered body consisting of metallic powder - Google Patents

Abstract

PURPOSE:To prevent collapsion of a molding during sintering by using the mold formed by a lost was method, molding metallic powder by injection in said mold, sintering the powder together with the mold, parting the mold after sintering and taking out a sintered body. CONSTITUTION:A ceramic mold is first manufactured by a lost wax method from a wax pattern having a required shape in a process for producing a sintered body by sintering metallic powder after compression molding. A master molding die is formed to the same shape as the cavity of the injection mold and is mounted to the injection mold. Metallic powder incorporated therein with a binder removing treatment and sintering together with the molds after injection molding and the sintered body is taken out by parting the mold after sintering.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a sintered body in which powder is compression-molded and then fired, and more specifically, a metal or alloy body is produced by a loss-wax method. This is a method of injection molding using a mold, and relates to a method of manufacturing a sintered body in which the mold is fired together with the mold after injection molding to prevent the molded body from deforming during sintering.

J3 is involved in powder metallurgy and ceramics manufacturing, and compression molding methods for molding metal or powder into a predetermined shape include mold press molding, extrusion molding, and weighing methods D1.
However, in either method, the molded product meets the specified JB
The binder and the sintering process are made into a product, for example, after mold press molding, the molded body is fired as is or embedded in alumina powder.

When compression molding wood, a binder is usually used to improve the molding properties, but especially when sintering, binder is used.
During piping, the binder melts, reducing the strength of the molded product and making it more likely to lose its shape1.To prevent this from happening, #4 large particles such as alumina powder are used. d1 is used to avoid sintering by embedding a molded body in a refractory material, but in the case of a large or complex shaped molded body, d1, which involves embedding the molded body in a refractory material, is also susceptible to deformation.

On the other hand, the index molding method has been put into practical use as a method for molding ceramics, and the injection molding method for metal powder is also being researched. Direct Q/J extrusion molding, embedding the molded body in refractory powder (removal of bisider), sintering to make the product
However, it is necessary to use a large amount of binder such as resin to improve the fluidity required during injection molding.
Even if it is embedded in a refractory powder with a relatively low specific gravity during firing, the so-called backup effect of the compact cannot be expected, and the complex, thin-walled compact may lose its shape.

There is.

In addition, there are 656 powder molding methods such as mold press molding, container encapsulation molding, extrusion molding, rolling molding, thermal spray molding, and the above-mentioned injection molding, but all of these methods produce large amounts of molded bodies with complex shapes. It is difficult to produce products, and as mentioned above, the product loses its shape before sintering. In view of this, d3 is applied to powder metallurgy.
The purpose is to remove the binder and to create a method for manufacturing sintered bodies that prevents the molded body from losing its shape during sintering.It also enables molding and sintering of so-called three-dimensional complex-shaped products that are impossible with conventional molding methods. The purpose of the present invention is to provide a method for producing a sintered body that is possible and can be produced with a high yield.

That is, this invention uses a mold based on the d3-C lost wax method in a method for producing a sintered body in which metal powder is compression molded and then fired, and the metal powder is injection molded into this mold. The method for producing a sintered body is characterized in that the whole mold is fired after OJ molding, the mold is broken after sintering, and the -C sintered body is taken out.

The sintered body raw materials to which the method of the present invention is applicable) [The powders are all metals and alloys, and have a carbon-resistant effect on ceramics.

More specifically, the present invention relates to a method for producing a sintered body in which metal powder is compression-molded and then fired, which is characterized by the following step -C1.

■Tokoro 9. From the Q-shaped wax pattern, remove the lost wax to create a Viramix mold, ■Mold the outside of the mold to the same shape as the via and r of the injection mold, and ■Inject the mold. It is installed in a mold for molding, and the metal powder mixed with a binder is injection molded into the mold. After the injection molding, the mold is treated with a Bli binder and sintered. and take out the sintered body.

Ceramic molding by lost wax removal according to the present invention may be a mold made by any of the known solid molding methods and ceramic silica molding methods.

The solid mold method is almost similar to the required product shape and takes into account shrinkage.The model of the N method is made into a wax pattern, and fine particles of refractories and a binder are applied to the surface of the model. Cover with the mixed slurry (coating), and until it dries, sprinkle (sanding) a refractory made of phase melon. 1! Filled with refractory powder, dried at 92 U, dewaxed at a specified humidity, and fired if necessary. In the process, corfing and sanding were repeated several times to create the desired wax pattern, and the required 19mm diameter was obtained.

- Refractory powder T3, alumina porcelain powder, and oxide ceramics used in the slurry and binding are used for the slurry and binding. Depending on (select as appropriate) J:
1゜ To cover the use as a lamix mold for ail injection molding of this invention, an outer shape for mounting on an injection mold,
For example, is it necessary to shape the shape of a simple cylinder? '
Therefore, it is desirable to mold and sinter a refractory powder into a sealed ceramic seat molding mold having an appropriate thickness to form the outer shape of the receptacle to be attached to the injection mold.

Next, the ceramic mold is inserted into the -VV hee of the injection mold, and the predetermined q4 output is fJ', L.
) However, by unifying the shape and usage of the above-mentioned Tobii, the number of design types and work efficiency will be improved.

Prior to injection molding, in order to cover the metal powder with a fluid suitable for injection molding, V) uncomposed, depending on the particle size -C select one type and amount of binder, heat knead to form a mixture, and further as necessary. Then, 'II) Determine the injection temperature and force depending on the composition and binder.

The IB2 binder treatment after injection molding is performed in a heating furnace with the ceramic mold, or in a firing furnace.
11+2 binder treatment and sintering are performed on l1iJ poem to complete firing.

After firing, the entire process is completed by removing sand or molding and removing the sintered body.

Furthermore, this invention relates to a method for manufacturing a sintered body in which metal powder is compression molded and then fired. By firing the mold together with the injection molding, the molded body is sufficiently backed up, which prevents the molded body from deforming during sintering, especially during binder removal, and significantly improves the dimensional accuracy of the product. Furthermore, it has the effect that complex-shaped and thin-walled sintered bodies can be manufactured easily and manually.

In addition, wax pattern molds for manufacturing ceramic molds can be manufactured at low cost due to low-pressure injection, and as mentioned above, ceramic molds are easy and cheap to manufacture because they are made from refractory powder. There is 11iC. Injection molds are usually i! The mold is octavalent because it requires pressure and wear resistance of 1q and 1x1, but this invention unifies the +1 and wear resistance of the mold to a simple shape and usage, making it possible to have 4M types of molds. Therefore, an embodiment according to the present invention will be shown for a 1°J suit in which the installation +ii°i cost is reduced, and the effects will be clarified. Here, we will show a case in which iron powder is used to manufacture and cover a thin plate with an arcuate cross section, in order to achieve a ratio compared to the conventional manufacturing method.

First, paraffin wax was injected at 50° C. to 90° C. into a thin plate model manufacturing mold having an arcuate cross section to create a wax pattern.

Add this wax pattern to acetone or acetone.

After washing with a methanol mixture, five layers of sanding were applied.

The following ingredients were used for the slurry to be coated: Zircon sand (coarse #809 made by Kagakusha) was used for sanding the first and second layers, and 4 non-dings were used for the third to fifth layers. (Yo, high alumina (particle size 0.3~0
．． 7 nu11*Nissan Chemical Target), each shake 11
After drying for 2 to 3 hours for the first to fourth layers, only the fifth layer was dried for 48 hours. Next, the mold was molded into a rectangular parallelepiped using the same slurry components.

Slurry component: Binder: ;% Hydrosilicic acid, Product name: Snow] Tsuku S1 manufactured by Nissan Kazoku, ioog, Fireproof 1'r) Not yet: Product name: Zircon laureate (#3!□
IO) Manufactured by Meku Kagakusha, 350 (], Surfactant: Product name 21-Rex] -△[310%
Aqueous solution, made by Meku Kagakusha, 0.05 + I + antifoaming agent 2F19
Product name Azuma Silicone 5115! ioo, manufactured by Toshisha,
The blending ratio of 0.1 g was adjusted with water so that the viscosity according to the cup viscosity test No. 4 would be 25 seconds.

900°C to 1000°C, 0,
5 hours of dewaxing and 900℃~1050℃, 1
After baking for a while, mold the Reramix mold.

Mount this ceramic mold into a designated injection mold?
1, and the iron powder was injection molded.

The iron powder composition is pure iron powder with carbon added l+2%i
Copper glaze, paraffin wax 7, OW L 9
ii, PolyX [Blen 0. ≦+wt%, zinc stearate 1.4vt%, balance 350 mTS] or less].

Heat-knead the IJ11 mixture using the melted wax of the wax mentioned above and use it to reduce the temperature to 2111111 or less. +? "n (molded.

Each ceramic mold was sintered in a nitrogen atmosphere using a 2-bar oven (II).

Heat pattern is 10℃/1 from room temperature to 300℃
H mixture ratio of 1, 300℃~1200℃ is 60℃/b
That's the temperature rate! +1 Warm 1200℃X O, held for 5 hours, then slowly cooled.

After sintering is completed, the sand is removed and the sintered body, which has an arc-shaped cross section, is poured into the stomach.

Further, using the same iron (2), after press molding with a die, firing was performed using the heat pattern described above to produce a thin plate with an arcuate cross section according to the conventional manufacturing method.

When 50 pieces of each product were manufactured using each manufacturing method, the number of products that lost their shape was 30 times using the conventional manufacturing method, but there was no product that lost its shape using the method of the present invention, which prevented the molded products from losing their shape. It is found that injection molding of jlf2 and iron powder can be fully put into practical use.

Applicant: Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] 1. In a method for manufacturing a sintered body in which metal powder is compressed and then fired, a mold using a lost wax method is used,
A method for manufacturing a sintered body, which comprises injection molding metal powder into the mold, firing the mold together after injection molding, and removing the sintered body from the mold after sintering.