JPS6144106A - Warm powder molding method - Google Patents

Abstract

PURPOSE:To produce precision worked parts having high accuracy and high strength by mixing a specific amt. of release material with a pulverized superplastic material consisting of ultrafine crystal grains, heating the material to the temp. range where superelasticity is induced and subjecting simultaneously the material to molding and solid diffusion-joining. CONSTITUTION:Fine particles of a Zn-22% Al alloy, etc. sized at <=50mu are produced by an atomizing method, etc. as the superplastic material. The powder raw material 8 mixed with 1-10% MoS2 by weight with such pulverous superplastic material is charged from a hopper 7 into a lower die 7. While the powder is pressurized by an upper die 10, the upper die 10 and the lower die 9 are heated in heating furnaces 11, 12 to heat the material 8 to 250-270 deg.C by which the material is subjected to superplasticization, molding and solid diffusion-joining. The molding is taken out of the dies 9, 10 and is sintered at 350 deg.C in an inert gaseous atmosphere of N2, etc. The precision worked parts having the excellent dimensional accuracy and high strength are thus produced.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This BAF! , concerning precision processing methods for precision parts, electronic parts, and mechanical parts, such as watch parts and exterior parts for portable watches.

[Conventional technology]

Conventionally, known methods for processing precision parts include machining typified by presses and lathes, powder molding methods in which powder is molded and then sintered, and precision casting methods typified by die casting 8a stwax.

[Problem that the invention seeks to solve]

However, with conventional machining methods, the more complex the shape of the part, the more man-hours required for machining, resulting in higher costs, and the powder molding method causes dimensional changes due to cracks and sintering, requiring machining as secondary processing. Precision casting methods have been actively developed in recent years, but it is difficult to completely eliminate cavities, which are serious defects, and dimensional changes inevitably occur during melting and cooling of the metal, so high precision is required. Precision parts had drawbacks such as requiring 100% inspection or secondary processing.

Therefore, in order to solve these conventional drawbacks, the present invention has the following features:
Focusing on the welding effect of superplastic materials, by heating fine-crystalline superplastic materials that have not been powdered during powder molding to perform solid-state diffusion bonding, precision machined parts can be made with high precision without reducing their strength. The purpose is to process with precision and in a short time.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention aims to heat a molding powder raw material prepared by mixing a mold release agent with a fine grained superplastic material powder produced by atomization to a temperature range in which the superplastic material powder exhibits a superplastic phenomenon. By heating and performing solid-state diffusion bonding simultaneously with molding, molded parts with significantly superior dimensional accuracy can be obtained. By mixing a mold release agent into the TFCI powder in advance, the part to be molded can be easily released from the molding die.

[Effect]

By performing warm powder compaction as described above, it is easy to cause the super-slip phenomenon, solid-state diffusion bonding is possible in a short time, and even parts with complex shapes can be made dense with a density of 100%.
High-strength molded parts with high dimensional accuracy can be efficiently obtained through continuous processing and can be easily released from the mold. Furthermore, if annealing is performed after forming, the strength can be increased without exciting the growth of fine crystal grains.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Figure 11 is a detailed explanatory diagram of the present invention, in which the superplastic side powder (1) and the mold release agent (2) are mixed in step 8, solid-state diffusion bonding and molding are performed at the superplasticity development temperature in step 4, and annealing is performed in step 6. The details of the present invention will be further explained with reference to the manufacturing conditions after each step.

(1) Superplastic powder φ material 22chiA! - Residue zn - Powder particle size: Powder t-aao below μ or less was held at a temperature of 850° C. to 850° C. for several hours, and then cooled with water to refine the crystal grains.

(2) Mold release agent Molybdenum disulfide (8) Mold release agent for superplastic material powder VC (2) of mixture (1) t-1 to 10
and mixed.

(4) Warm opening molding Solid state diffusion bonding between powders and molding were performed using a warm molding machine shown in FIG. The powder raw material for molding 8 mixed in step (3) is supplied from the powder supply hopper in step 7 to the lower molding mold 9, and after being pressurized and held in the upper molding mold 10, the lower molding mold 9 is transferred to the push-up device 13. The warm molded product was then discharged. @Open molding conditions are shown below.

・Temperature: 250°C to 270°C ・Holding time: 15 to 30 seconds Φ Molding pressure: 7 to 15 ton/cm Oita.

(5) N as an inert atmosphere for annealing! Using a gas, the mixture was kept at 350° C. for 1 hour in this atmosphere and then cooled in the furnace.

(6) Various characteristics of the product Table g1 shows various characteristics of the product obtained in the above process.

In Table 1, the packing density, machinability, and dimensional accuracy depend on the powder particle size of the ultra-hard material, the pressure during molding, and the temperature holding time. The higher the retention time, the better the density close to 100% can be obtained.The dimensional accuracy is also the same, and within the conditions of the above example, the sample size is outer diameter φ20I, thickness t = 0.5 to 2.
The mechanical strength of 9, which had no change in OII+a, was increased by annealing, and the strength was comparable to that of products using other processing methods (for example, die casting) using the same particles.

Furthermore, various experiments were conducted regarding the influence of molybdenum disulfide as a mold release agent #9, and the mold release property improves as the Vc increases, but 1
It was found that when the content exceeds 0%, the strength decreases. Therefore, molybdenum disulfide as a mold release agent has a weight ratio of 1
~H1 ratio is good, 1D An additional effect was observed in machining tests where the addition of molybdenum disulfide broke up the burr during cutting and turned it into powder, improving the rigidity by several steps compared to cutting machining of die-cast products. It was done. Further, the reason why the powder particle size of the superplastic material is limited to φ50μ or less is due to the efficiency during warm forming, the strength and quality of the finished product (occurrence of dimensional change bundles), etc.

〔Effect of the invention〕

As explained above, this invention focuses on the welding action of superplastic materials, and by simultaneously performing solid diffusion bonding of finely powdered fine grained superplastic materials during powder molding processing, high precision and high strength precision can be achieved. One effect is that processed parts can be manufactured at low cost using a completely new processing method.

[Brief explanation of the drawing]

FIG. 1 is an explanation of the manufacturing process according to the present invention, and FIG. 2 is a sectional view of a warm powder compacting machine used in the present invention. 7... Powder supply hopper 8... Powder raw material for molding 9/e, lower mold 10... upper mold 11... upper mold heating furnace 12... lower mold Heating furnace 13--Pushing device and above

Claims (3)

[Claims] (1) Fill a desired mold with a molding powder raw material consisting of a superplastic material powder with a diameter of 50μ or less mixed with a mold release agent, and solid-state diffusion bonding in a temperature range where the superplastic material powder exhibits a superplastic phenomenon. This is a warm powder compaction method that is characterized by performing both molding and molding at the same time. (2) The warm powder molding method according to claim 1, wherein molybdenum disulfide of 1 to 10% by weight is used as the mold release material. (3) The warm powder forming method according to claim 1, wherein the molded part is annealed in an inert gas atmosphere after the forming process.