TWI752689B - Melt-molding metallurgical method - Google Patents

Abstract

A metallurgical method for fusion molding, comprising the following steps: (A) preparing raw material powder and bonding material. (B) mixing the raw material powder and the binding material to obtain pellets. (C) applying pressure to the pellets, thereby producing a solid material. (D) heating the solid material so that the solid material partially melts and becomes a liquid material. (E) Pushing the liquid material with the solid material that has not yet melted so that the liquid material is injected into the forming space. (F) Allowing the liquid material in the forming space to cool and solidify into a blank. (G) A sintering operation is performed on the blank, thereby producing a finished product. In the present invention, by directly injecting the liquid material into the molding space, the fluidity is better without additional processing, and by controlling the solid material, the injection amount and injection speed can be precisely controlled.

Description

Melt-molding metallurgical methods

The present invention relates to a mold manufacturing process, in particular to a melting mold metallurgical method.

In order to produce metal workpieces, the most traditional processing method is "casting". Specifically, "casting" is to melt the metal material into a liquid state at high temperature, pour it into a mold, and then cool it to form. However, casting does not only require heating the material to a relatively high temperature, it must also maintain the temperature of the material prior to injection into the mold. In addition, the mold must be able to withstand the corresponding high temperatures to allow the material to take shape. What's more, it is necessary to consider the danger brought by high temperature and set up corresponding safety facilities. Therefore, the technology of "powder metallurgy" was developed in modern times. Specifically, "powder metallurgy" is to put metal powder into a mold, and then extrude the metal powder into a blank by stamping. At this time, the aforementioned blank has been initially formed into the appearance of the workpiece, but the structural strength is still quite low. Therefore, sintering must also be performed on the aforementioned blanks in order to increase the structural strength. The advantage of using "powder metallurgy" is that it is not necessary to heat the metal material to a liquid state, as long as it reaches the recrystallization temperature. Naturally, the aforementioned problems of "maintaining the material temperature", "the mold must be able to withstand the corresponding high temperature", and "the danger caused by high temperature" can be avoided or reduced.

In addition, in recent years, the above-mentioned "powder metallurgy" technology has been mixed with "injection molding" for manufacturing plastic products to form a "metal injection molding" technology (Metal Injection Molding, abbreviated as MIM). Specifically, "metal injection molding" is to inject metal powder into a mold from an injection machine, and then sinter it after molding in the mold. Compared with the traditional "powder metallurgy", the metal powder used in "metal injection molding" is finer, so it has fluidity and can be injected by the injection machine. In addition, due to the finer metal powder, a denser metal structure can be obtained after sintering. Therefore, the application of "metal injection molding" technology can produce high-density, high-precision and complex-shaped metal workpieces. However, "Metal Injection Molding" still has the disadvantage of not being able to manufacture large workpieces. This is because the fluidity of metal powders is still poor compared to fluids. In addition, based on the characteristics of injection molding, the injection amount can only be controlled by the value of the holding pressure as a control parameter, and the injection amount cannot be accurately adjusted for different numbers and sizes of mold cavities.

In addition, the aforementioned techniques all require the injection of liquid metal or metal powder. Therefore, the mold must be provided with a sprue or a runner. After the material is formed, the material remaining in the sprue or runner will form a slug. In order to remove the slug, additional processing must be performed after the material has solidified or sintered. For example, most of the material head is removed by shearing, and then a smooth surface is processed by polishing and grinding. It should be emphasized that the slug cannot be cut off before sintering. Because the structural strength of the blank before sintering is quite low, performing shearing may cause other adjacent parts to collapse together. However, after sintering, the structural strength of the blank becomes quite high again, making removal of the slug quite difficult.

Therefore, the purpose of the present invention is to provide a melt-molding metallurgy method with better fluidity, no additional processing, and precise control of injection amount and injection speed.

Thus, the metallurgical method for melting molding of the present invention comprises the following steps:

(A) Preparation of raw material powder and bonding material.

(B) mixing the raw material powder and the binding material to obtain pellets.

(C) applying pressure to the pellets and passing the pellets through a die, thereby producing a solid material.

(D) heating the solid material so that a portion of the solid material adjacent to a forming space melts and becomes a liquid material.

(E) Pushing the liquid material with the solid material that has not yet melted so that the liquid material is injected into the forming space.

(F) Allowing the liquid material in the forming space to cool and solidify into a blank.

(G) A sintering operation is performed on the blank, thereby producing a finished product.

The effect of the present invention is that, since the part of the solid material adjacent to the forming space will melt and become the liquid material, the fluidity is better than that of powder. In addition, the liquid material is directly injected into the forming space, and the blank becomes a finished product after sintering, without additional processing. In addition, the user can not only control the force required to push the solid material, but also control the moving speed of the solid material, so as to precisely control the injection amount and injection speed.

Referring to FIG. 1 , FIG. 2 and FIG. 3 , an embodiment of the melt-molding metallurgical method of the present invention includes steps S1 to S10 , which are described in detail later.

In step S1, raw material powder and bonding material are prepared. The melting point of the binding material is lower than the melting point of the raw material powder. In this embodiment, the composition of the raw material powder is glass, but it can also be metal or ceramics, but this is only an example and should not be limited thereto. In addition, in this embodiment, the bonding material is essentially a bridging agent, and common bridging agents include paraffin, polyurethane, acrylate, etc., but this is only an example, and should not be limited thereto.

Step S2, mixing the raw material powder and the binding material to prepare pellets. Specifically, the raw material powder and the binding material can be uniformly mixed by kneading. How to perform kneading and obtain these pellets is a common method in the art, and is not the focus of this case, so it will not be repeated here.

In step S3, pressure is applied to the pellets and the pellets pass through the one-eye die 1, so as to obtain a solid material S. The solid material is in the form of wires or rods. Specifically, the eye mold 1 has a narrow channel 11 . When the pellets are pushed by a considerable degree of pressure and pass through the channel 11, they will be pressed against each other and heated up, thereby softening or melting the part belonging to the binding material in each pellet (the part belonging to the raw powder remains solid). , and then the various pellets are bonded together and formed into the solid material S.

In step S4, a molding device 2 is prepared (as shown in Fig. 3). The molding device 2 includes a conveying unit 21 disposed downstream of the eye mold 1 along a conveying direction T and used to drive the solid material S to move along the conveying direction T, and a conveying unit 21 disposed downstream of the conveying unit 21 along the conveying direction T A heating unit 22, and a moulding unit 23 arranged downstream of the heating unit 22 along the conveying direction T.

The conveying unit 21 may include two rollers that jointly grip the solid material S. In this way, the moving distance of the solid material S, the moving speed of the solid material S, and the force for pushing the solid material S can be further controlled by controlling the rotational speed and clamping force of the rollers. However, this structural design is only an example, and those skilled in the art may also choose other ways to push the solid material S according to requirements, which should not be limited thereto.

The heating unit 22 includes a body 221 , a nozzle 222 installed on the downstream side of the body 221 , a heating pipe 223 passing through the body 221 , a heat source 224 embedded in the body 221 , and a heat source 224 adjacent to the heat source 224 . temperature sensor 225. The nozzle 222 is connected to the heating pipe 223 . The heating pipe 223 and the nozzle 222 together define a heating channel 226 for the solid material S to be input. The heating channel 226 penetrates the body 221 and the nozzle 222 .

It is worth noting that in this embodiment, the heating tube 223 only partially penetrates into the body 221 so that the junction of the nozzle 222 and the heating tube 223 is also in the body 221 . However, in other variations, the heating tube 223 can also pass through the body 221 so that the junction of the nozzle 222 and the heating tube 223 is outside the body 221 . This is just an example and should not be limited.

The moulding unit 23 includes two moulds 231 which are joined up and down. The molds 231 can jointly define a molding space 232 . The molding space 232 has a filling port 233 communicated with the heating channel 226 . The upper mold 231 is defined as a first mold 234 , and the lower mold 231 is defined as a second mold 235 . The second mold 235 has an insertion hole 236 into which the nozzle 222 is inserted. The insertion hole 236 communicates with the molding space 232 . The filling port 233 is located at the junction of the molding space 232 and the insertion hole 236 .

It should be noted that in this embodiment, the number of the molds 231 is two, but this is only for example, and those skilled in the art can use three, four or more molds 231 as required, and should not This is the limit.

In step S5 , the conveying unit 21 is activated so that the solid material S is input into the heating channel 226 of the heating unit 22 from the eye mold 1 .

In step S6 , the heating unit 22 is activated so that the solid material S in the heating channel 226 is heated by the heat source 224 . When the heating unit 22 heats the solid material S in the heating channel 226 , a portion of the solid material S adjacent to the nozzle 222 will melt and become a liquid material L. It should be noted that the liquid material L is heated to a temperature between the melting point of the bonding material and the melting point of the raw material powder. Therefore, the composition of the liquid material L still contains the raw material powder which has not yet been melted. However, from a macroscopic point of view, the liquid material L is a fluid.

In the present embodiment, the portion of the heating channel 226 adjacent to the filling port 233 is gradually reduced, so the pressure of the liquid material L will gradually increase during the process of moving toward the filling port 233 , so that the liquid material L can gradually increase from the filling port 233 injection into the molding space 232 .

In addition, the user can control the heat source 224 through the temperature sensor 225 to make the solid material S reach a sufficiently high temperature and melt.

In step S7 , after the conveying unit 21 and the heating unit 22 are activated, the unmelted solid material S is driven by the conveying unit 21 to push the liquid material L, so that the liquid material L is injected into the molding space 232 through the filling port 233 .

It should be emphasized that, in this embodiment, step S5 is first performed to input the solid material S into the heating channel 226, and then steps S6 and S7 are performed to achieve the state shown in FIG. 2 . However, there is no specific sequence relationship between the step S5 and the step S6, and may be performed sequentially, simultaneously, mixedly or repeatedly according to requirements. The user can use the molding device 2 by manual operation or automatic control.

In step S8 , the molding unit 23 is cooled so that the liquid material L in the molding space 232 is cooled and solidified into a blank 3 . It should be noted that, after curing, the molds 231 will be separated from each other so that the molding space 232 is opened to the outside, so that the blank 3 can be taken out (as shown in FIG. 4 ).

In step S9 , a degreasing operation is performed on the blank 3 to remove the bonding material in the blank 3 . The aforementioned degreasing operation can be specifically a process of heating, washing, solvent washing or mixing the aforementioned three, and those skilled in the art can select appropriate technical means according to different bonding materials to achieve removal of the blank 3. Purpose of bonding material.

In step S10, a sintering operation is performed on the blank 3 to obtain a finished product. During sintering, the microstructure of the blank 3 will change, thereby increasing the structural strength. In detail, after the degreasing operation, the blank 3 is mainly composed of the raw material powder, but the microstructure is very loose, and the overall structural strength is still quite poor. When heated above the recrystallization temperature (ie, upon sintering), the grain boundaries between the molecules disappear, allowing the molecules to rearrange and recrystallize. In this way, the molecules in the blank 3 can generate an integrated microstructure, which naturally improves the structural strength and becomes a finished product that can be sold.

In this embodiment, since the portion of the solid material S adjacent to the forming space 232 will melt and become the liquid material L, the liquid material L is also injected into the forming space 232 . Compared with the prior art, the liquid material L is a fluid, and its fluidity is naturally better than that of powder, so the present embodiment can be applied to make larger workpieces. In addition, the highest temperature required in this embodiment only needs to reach the recrystallization temperature, and does not need to reach the melting point of the raw material powder. Naturally, it can be avoided or reduced in the prior art "maintaining the material temperature", "the mold must be able to withstand the corresponding High temperature” and “high temperature causes danger”.

In addition, since the liquid material L is directly injected into the molding space 232 through the pouring port 233 , the molds 231 do not need to be provided with a pouring port or a runner. In this way, the blank 3 naturally does not produce a slug, so that the blank 3 becomes a finished product after sintering, and no additional processing is required.

In addition, the liquid material L leaving the heat source 224 and going to the pouring port 233 is gradually cooled. In order to prevent the material remaining in the heating channel 226 from solidifying due to the cooling of the molding unit 23 , after the injection is completed, the solid material S can be reversely transported through the conveying unit 21 , so that the liquid material L adjacent to the pouring port 233 is withdrawn without curing. Until the next processing, the liquid material L is pushed from the heat source 224 to the pouring port 233, so that the liquid material L can be properly used and the effect of almost no waste can be achieved. In addition, keeping the heat source 224 on can not only maintain the liquid material L at a certain temperature without solidifying, but also facilitate continuous processing.

In addition, when the user executes according to this embodiment, not only the force required to push the solid material S, but also the moving speed of the solid material S can be controlled through the conveying unit 21 . Different from the prior art, the injection volume and injection speed can only be estimated from the holding pressure. Since the solid material S is linear or rod-shaped, the present embodiment can also calculate the injection volume through the length of the solid material S that has been fed. and injection speed, so this embodiment can control the injection amount and injection speed more precisely.

To sum up, in the metallurgical method of melt molding of the present invention, since the portion of the solid material S adjacent to the molding space 232 will melt and become the liquid material L, the fluidity is better than that of powder. In addition, the liquid material L is directly injected into the forming space 232, and the blank 3 becomes a finished product after sintering, without additional processing. In addition, the user can not only control the force required to push the solid material S, but also control the moving speed of the solid material S, so as to precisely control the injection amount and injection speed, so the object of the present invention can indeed be achieved. .

However, the above are only examples of the present invention, and should not limit the scope of implementation of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the patent specification are still included in the scope of the present invention. within the scope of the invention patent.

1: Eye mold

11: Channel

2: Molding device

21: Conveyor unit

22: Heating unit

221: Ontology

222: Nozzle

223: Heating tube

224: Heat Source

225: temperature sensor

226: Heating channel

23: Molding unit

231: Mold

232: Molding space

233: perfusion port

234: First Die

235: Second mold

236: Insertion hole

T: conveying direction

S: solid material

L: liquid material

S1~S10: Steps

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Fig. 1 is a flow chart of an embodiment of the melt-molding metallurgical method of the present invention; Fig. 2 is a conceptual schematic diagram of this embodiment; 3 is a schematic structural diagram of an eye mold and a molding device of the melt-molding metallurgical method of the present invention, showing that a liquid material is injected into a molding space; and Figure 4 is a view similar to Figure 2 showing the two dies separated from each other to allow a blank to be removed.

S1~S10: Steps

Claims (6)

A metallurgical method for fusion molding, comprising the steps of: (A) preparing raw material powder and binding material; (B) mixing the raw powder and the binding material to obtain pellets; (C) applying pressure to the pellets and causing the Equal material particles pass through an eye mold, thereby producing a solid material; (1) prepare a molding device, the molding device comprises a conveying device arranged downstream of the eye mold along a conveying direction and used to drive the solid material to move along the conveying direction unit, a heating unit disposed downstream of the conveying unit along the conveying direction, and a molding unit, the heating unit comprising a body, a nozzle installed on the downstream side of the body, and a nozzle penetrating the body and the nozzle for the A heating channel for solid material input, the molding unit includes at least two molds, and the molds can jointly define a molding space, and the molding space has a filling port communicated with the heating channel; (J) Activate the conveying unit to make the solid state The material is input into the heating channel of the heating unit from the eye mold; (D) heating the solid material to make the part of the solid material adjacent to the forming space melt and become a liquid material; (E) using the solid material that has not yet melted to push the solid material liquid material, so that the liquid material is injected into the forming space; (F) cooling and solidifying the liquid material in the forming space into a blank; (H) performing a degreasing operation on the blank to remove the blank bonding material in the parts; and (G) A sintering operation is performed on the blank, thereby producing a finished product. The melt-molding metallurgical method according to claim 1, wherein, in the step (A), the raw material powder is composed of metal, glass or plastic. The melt-molding metallurgical method according to claim 1, wherein the solid material in the step (C) is in the shape of a wire or a rod. The melt-molding metallurgical method of claim 1, wherein step (D) is to activate the heating unit so that the solid material in the heating channel is heated by the heating unit, and a portion of the solid material adjacent to the nozzle will be heated by the heating unit. melt and become the liquid material. The melt-molding metallurgical method according to claim 1, wherein the unmelted solid material in step (E) is pushed by the conveying unit, so that the liquid material is injected into the forming space from the nozzle. The melt-molding metallurgical method as claimed in claim 1, wherein the molding unit described in step (1) comprises two molds that are aligned up and down, and the mold located on the upper side is defined as a first mold, and the mold located on the lower side is a mold A second mold, the second mold has an insertion hole for inserting the nozzle, the insertion hole communicates with the molding space, and the filling port is located at the junction of the molding space and the insertion hole.

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