JPH10298610A - Mold and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a highly accurate sintered metallic mold for forming in a short time and at a low cost by compacting a composite composed of alloy fine powder of the metallic mold composition and agar powder as raw material into a massive plate material, engraving a shape for reversing into the shape of the formed product to this plate material and sintering the obtd. green compact. SOLUTION: The composite composed of the alloy fine powder having the same component composition as the metallic mold steel and binder of the agar powder, etc., as the raw material, e.g. the powdery compound composed of 84.95% SKD-6 having 10-15 μ average particle diameter, 2.60% powdery agar, 0.78% stearic acid and 11.67% purified water, is compacted to the massive plate material by compressing or extruding. The shape for reversing into the shape of the formed product is engraved on this plate material to form the green compact. This engraving is desirable to be directly engraved in a machining center, etc., by a program control for machining under consideration of sintering shrinkage factor of e.g. 20% based on a product drawing. This green compact is charged into a vacuum sintering furnace and sintered at e.g. about 1240 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die, and more particularly to a molding die manufacturing method for manufacturing a molding die by sintering metal powder, and a die manufactured by the method. About.

[0002]

2. Description of the Related Art Heretofore, when making a plastic molding die, first, a prototype mold is manufactured based on a drawing, and then a plastic product is actually molded using the prototype die. After confirming the function of the product based on the molded product in this way, reconfirming the mold structure that affects productivity, making necessary modifications as needed, and then proceeding to the production of mass production dies. Through these procedures, a mold for plastic molding was created. However, such a mold making method requires a lot of time for manufacturing, and the manufacturing cost is considerably high.

[0003] Therefore, in recent years, there has been an increasing demand for the production of such mass-producing dies to greatly reduce the production time and the production cost, and in fact, some methods are being embodied and being spread.

The first method uses a CA based on a product drawing.
A model made of photoreactive epoxy resin is manufactured by an optical molding system linked to D / CAM, and the structure and function of the product are confirmed using this model. Then, the block is formed by a machine tool such as an electric discharge machine linked to CAD / CAM. This is a method of producing a mold for mass production through cutting and engraving the shape and inverted shape of the product on the die steel of the ingot material, followed by finishing and assembling steps. According to this method, it is possible to omit the production of the prototype mold only by cutting and engraving the shape of the product and the inverted shape of the die steel, thereby saving time and cost.

A second method is disclosed by the inventor of the present invention in Japanese Patent Application No. 8-141386. First, based on a product drawing, a stereolithography system interlocked with CAD / CAM is performed in a later step. A master model made of epoxy resin is created in consideration of the sintering shrinkage in the sintering process. Then fix this master model to the bottom of the metal formwork,
A molding compound made from a powder agar and an alloy fine powder having the same composition as that of the mold steel as a raw material is put from above the master model, and heated and compression-molded to form a molded body integrated with the master model. Thereafter, the master model is removed from the compact, and the compact is dried and fired in a sintering furnace to obtain a sintered metal having the same mechanical property values as those of conventional mold steel. A prototype metal mold is obtained by performing dimension correction and finishing on the sintered metal body thus manufactured and assembling the same.
This is a method in which a prototype is formed using this mold to confirm the shape and the formability, and then, if necessary, corrected again to use the prototype as a mass production mold. In this method, the prototype mold can be used as it is as a mold for mass production.
Saves time and money.

[0006]

However, the first method is that the introduction cost of the stereolithography system linked to CAD / CAM becomes enormous, and the molded product is limited to a photoreactive epoxy resin suitable for the stereolithography system. That the photoreactive epoxy resin is extremely expensive, the shape of the product can be confirmed, but the moldability cannot be confirmed until the mass production mold is completed. There are problems such as extremely low processing efficiency and long processing time for cutting die steel.

Further, in the second method, the prototype die is burned in a very short time as compared with the long-time processing caused by processing the hard-to-cut die steel as in the first method. It can be completed as a finished product, it can be used to check the shape and function of the product using the desired resin and the moldability using this prototype, and it can be converted to a mass production type just by modifying the prototype Although there are advantages such as what you can do,
Similar to the first method, a considerably expensive CAD / CAM-linked stereolithography system and equipment for compression molding are required, and the use of expensive photoreactive epoxy resin increases the cost. There is such a problem.

The present invention solves these problems at the same time.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, a mass of a composite material composed of powder agar and metal powder is engraved with a shape inverted from a shape of a molded product and a molded body. No, a sintered mold for molding is manufactured by sintering the molded body.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. However, it should be understood that the present invention is not limited to these embodiments.

According to the present invention, as described in the second method,
Instead of manufacturing a molded body integrated with a master model created by an optical molding system by heating and compression molding a molding compound made from powder agar and alloy fine powder having the same component composition as metal steel First, a molding compound is formed from a fine powder of an alloy powder having the same component composition as the mold steel, and a powder agar as a binder for the fine powder, and then the molding compound is formed. In this method, a composite plate having a predetermined size is formed in advance by a compression molding method or a continuous extrusion molding method, and the composite plate is completely dried. In addition, as the binder of the alloy powder having the same component composition as that of the metal steel, in addition to powder agar, for example, carrageenan, alginic acid, polysaccharides such as pectin, glue and gelatin, starch and dextrin and those having gelling ability Derivatives, natural pastes such as gum arabic and guar gum, and synthetic pastes such as polyvinyl alcohol are considered. The common features of these binders are that they are soluble in water, do not melt when heated in a dried and solidified state, and have the ability to bind powder such as metal powder.

Next, instead of the mold steel conventionally purchased, the mold processor has described the above-mentioned alloy powder containing the alloy powder having the same composition as the mold steel and having a predetermined size. You buy composite boards. Next, the mold processor creates a cutting program in consideration of the sintering shrinkage rate based on the product drawing. Thereafter, the composite plate is mounted on a support of a cutting machine, and the composite plate is directly subjected to a cutting process based on the above-mentioned program control to produce a cut body.

The block-shaped composite plate material is made of powder agar and a fine powder of an alloy powder having the same composition as the die steel as described above, and is completely dried. Cutting can be performed very easily with a steel cutting jig. During cutting, heat is generated due to friction between the cutting jig and the work, but since the composite plate is completely dry, the powder that serves as a binder for the metal powder contained in the composite plate Agar does not soften or melt and deform. When the binder of the metal powder is a wax or a plastic-based binder, there is a risk of being softened or melted and deformed by the frictional heat.

[0014] The cutting body thus produced is
The state is the same as when the master model of the second method described above is removed from the molded body and dried. However, according to the method according to the present invention, the cut body can be obtained in an extremely short time, does not require an optical molding siltem linked to expensive CAD / CAM or equipment for compression molding, and furthermore, requires an expensive photoreactive epoxy. Since no resin is used, the cost does not increase.

Thereafter, the cut body is placed in a sintering furnace and sintered, whereby a mechanically equivalent to a mold obtained by engraving a conventional ingot of a mold steel by a cutting machine such as an electric discharge machine is obtained. A sintered mold exhibiting characteristics is obtained. When sintering the compact, the binder used in the compact, that is, the binder removal process of decomposing the binder before sintering becomes a problem, but in the present invention, the composite using powder agar as the binder is used. The inventor of the present invention previously disclosed injection molding of metal and ceramic powders for engraving and sintering a plate material (Japanese Patent Publication No.
No. 68566 and Japanese Patent Application No. 6-166847), the sintering of extruded and compression molded products of metal powder does not require a degreasing step, so that even complicated shapes and large sintered products can be easily obtained. You can get it.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described below. In Example 1, SK which is a typical mold steel is used.
A composite plate made from D-61 metal powder and agar powder as a binder is formed by a compression molding method, and after drying, the composite plate is formed into a shape based on a drawing by a processing machine such as a machining center. A method of manufacturing a mold for mass production by cutting and sintering the same is disclosed. On the other hand, in Example 2, a composite plate material using SKD-61 metal powder, which is a typical mold steel, and agar powder as raw materials was molded by a continuous extrusion molding method, cut into a predetermined length, and dried. A method of cutting the dried composite plate material into a shape based on the drawing with a processing machine such as a machining center and sintering to finish a mold for mass production is disclosed.

Example 1 First , a powdery compound was prepared in the following compounding ratio. Compounding ratio (% by weight) of compound SKD-61 (average particle size: 10 to 15 μ) 82.45 Powder agar (gel strength: 1500 g / cm ² ) 2.60 Stearic acid 0.78 Purified water 14.17

Powder agar, water and half of the metal powder are charged into a kneader and stirred while heating to 94 to 96 ° C. to completely dissolve the powder agar and to form a sol mixed with metal powder. create. Then, the temperature of the sol was lowered to around 60 ° C., and then stearic acid was added. While the remaining metal powder was dividedly charged, the pressure lid of the kneader was lowered, and the mixture was sufficiently kneaded under pressure. Cool to below C to make it gel and solidify. Next, the gelled composite material is pulverized by a pulverizer to obtain a powdery compound. Incidentally, in addition to powder agar, for example, carrageenan having a gelling ability, alginic acid, polysaccharides such as pectic substances, glue and gelatin, starch and dextrin and derivatives thereof,
Natural pastes such as arabic gum and guar gum, and synthetic pastes such as polyvinyl alcohol are considered.

Next, as shown in FIG.
Formwork 11 having a size of about 150 mm × 70 mm and having a heat medium circulation pipe 13 therein.
And about 2400 g of the powdery compound 15 adjusted above in a molding die constituted by a movable bottom 12 and a compressor 14 having a size insertable into the mold frame 11. And press 50kg /
The compressor 14 is pressed at a pressure of about ² cm ² for about 30 seconds.
Then, after releasing the pressure, the heat medium circulating pipe 13
A heat medium of 96 ° C. is circulated for 30 minutes, the powdery compound 15 is heated and dissolved to change into a sol-formed composite material, and a heat medium of about 60 ° C. is circulated through a heat medium circulation pipe 13 for about 15 minutes. Cool the solified composite to about 70 ° C.
Further, after applying a pressure of about 50 kg / cm ^{2 to} the compressor 14 for about 5 minutes, cooling water at about 20 ° C. is circulated through the heat medium circulating pipe 13 for about 30 minutes to cool the sol-formed composite material.
Solidify to form a gelled composite. Next, a pressure of about 100 kg / cm ² is applied to the compressor 14 for about 10 minutes to compress and dehydrate excess water from the gelled composite material, and then remove the compressor 14 and push up the movable bottom 12 to raise the gelled composite material. Remove the material. Next, the gelled composite material is dried by a known means to obtain a composite plate material having a size of about 99 mm × 148 mm × 30 mm and a weight of about 2200 g.

Next, the composite plate is mounted on a work support of a machining center, for example, and the sintering shrinkage is 20%.
In consideration of the above, the cutting procedure is programmed based on the drawing, and the cutting process is performed to obtain a cut workpiece.

The cut body is placed in a known vacuum sintering furnace and heated to 280 ° C. at a rate of 1 to 2 ° C./min.
After holding at 280 ° C. for 1 hour, the temperature was raised to 1240 ° C. at a heating rate of 2 to 3 ° C./min, after holding at 1240 ° C. for 2 hours,
Cool the furnace to 950 ° C. Then, after holding at 950 ° for 2 hours, it is cooled to room temperature at a cooling rate of 20 ° C./hour to obtain a sintered body.

The sintered body is finished and assembled into a mold, and a trial production is performed using a resin desired by the user, and the formability and the size and shape of the molded product are confirmed. The dimensions and shape are corrected as needed, and formed into a mass-production mold.

Example 2 First, a sol kneaded material was prepared in the following mixing ratio. Sol blending ratio of the kneaded material (wt%) SKD-61 (average particle size 10~15μ) 84.95 agar powder (gel strength 2000g / cm ²⁾ 2.60 Stearic acid 0.78 Purified water 11.67

Powder agar, water, and half of the metal powder are charged into a kneader and stirred while heating to about 94 to 96 ° C. to completely dissolve the powder agar, and mix the metal powder with the sol. Create Then, the temperature of the sol is increased to about 60 ° C.
Then, add stearic acid, add the remaining metal powder in portions, lower the pressure lid of the kneader, sufficiently knead the mixture, homogenize it, and make it a sol kneaded product. Transfer to a known continuous extruder maintained at 50-55 ° C. Next, the sol kneaded material was subjected to a predetermined size of a continuous extruder, for example, 150 m in width.
m, while continuously extruding from a die having a height of 31 mm, the mixture is cooled to obtain a gelled composite material. After the gelled composite material is dried, it is cut into a predetermined length, for example, 100 mm, to obtain a composite plate material having a width of 150 mm, a length of 100 mm, and a thickness of 31 mm. As the binder, in addition to powder agar, for example, carrageenan having a gelling ability, alginic acid, polysaccharides such as pectic substances, glue and gelatin, starch and dextrin and derivatives thereof, natural pastes such as arabic gum and guar gum, Synthetic pastes such as polyvinyl alcohol are conceivable.

The composite plate material is mounted on a work support table of a machining center, and a cutting procedure is programmed based on the drawing, taking into account a sintering shrinkage of about 20%, and a cutting is performed to obtain a cut body.

The cut body is placed in a known vacuum sintering furnace, heated at a rate of about 1-2 ° C./min to about 280 ° C., and maintained at about 280 ° C. for 1 hour. Speed about 2-3
The temperature is raised to about 1240 ° C. at a rate of ° C./min. After maintaining the temperature at about 1240 ° C. for about 2 hours, the furnace is cooled to about 950 ° C. Then, after holding at about 950 ° for about 2 hours, it is cooled to room temperature at a cooling rate of about 20 ° C./hour to obtain a sintered body.

The sintered body is processed and assembled as a mold, and a trial production is performed using a resin desired by the user, and the formability and the size and shape of the molded product are confirmed. The dimensions and shape are corrected as needed to complete the mass production mold.

[0028]

According to the present invention, there is provided a molded product integrated with a master model produced by a stereolithography system by heating and compression molding a molding compound made of a fine powder of an alloy having the same composition as powder agar and mold steel. Instead of how to make
Using a fine powder of an alloy powder having the same composition as powder agar and mold steel as a raw material, a composite plate of a predetermined size is preformed by compression molding or extrusion molding, and the composite plate is completely dried and cut. As the starting material for the processed body,
Based on the product drawing, the composite plate material is directly engraved by cutting program control taking into account the sintering shrinkage rate into a cut body, and this cut body is put into a sintering furnace and sintered, and the sintering mold is create.

As a result, (1) there is no need to introduce a stereolithography system linked to expensive CAD / CAM.
(2) It is no longer necessary to use an expensive photoreactive epoxy resin. (3) The molded product is not limited to the photoreactive epoxy resin suitable for the stereolithography system because it goes through a prototype mold process that can be easily transferred to a mass production mold. Can be confirmed. (4) Since the composite plate material can be cut very easily with a cutting tool made of tool steel such as high-speed steel, it does not require expensive electric discharge machines or electrodes for electric discharge machining, and is a machine that is normally used. Cutting center in a short time.

For this reason, the stage of manufacturing the composite plate and the step of cutting are separated, and the production of the composite plate requires a compression molding machine or an extrusion molding machine for mass production of the composite plate. Is much greater than the advantage of individual mold processors introducing stereolithography systems and compression molding machines that are linked to expensive CAD / CAM, and optical molding systems and compression are linked to expensive CAD / CAM. Problems that require equipment for molding can be solved.

Although the above-mentioned second method makes it possible to drastically reduce the time as compared with the conventional method of manufacturing a mold in which an ingot of a mold steel is directly cut and engraved, the present invention provides the following method. In order to engrave a composite board in the same time as a master model is manufactured by a stereolithography system linked to CAD / CAM in the second method, the problem that this photoreactive epoxy resin is extremely expensive is solved. Since there is no compression molding step required in the method 2, the processing time can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state when a compression molding machine for molding a composite plate used in the present invention is used.

[Explanation of symbols]

 11: Formwork 12: Movable bottom 13: Heat medium circulation pipe 14: Compressor 15: Powder compound 16: Press machine

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29C 33/38 B22F 3/02 P

Claims (11)

[Claims] 1. A molded body obtained by engraving a shape inverted to the shape of a molded product on a massive plate material of a composite material using alloy fine powder having the same component composition as a mold steel and a binder thereof as a raw material. A sintering mold for molding formed by sintering. 2. The molding die according to claim 1, wherein the binder is agar powder. 3. The binder is a carbohydrate having gelling ability, such as carrageenan, alginic acid, polysaccharides such as pectic substances, glue and gelatin, starch and dextrin and derivatives thereof, natural pastes such as arabic gum and guar gum, polyvinyl alcohol and the like. The molding die according to claim 1, which is selected from the group of synthetic pastes. 4. Forming a massive plate of a composite material comprising a binder and metal powder, drying the plate to form a starting material, and engraving the starting material with a shape inverted to the shape of a molded product. A method for manufacturing a molding die for sintering in which a molding sintering die is produced through various steps of forming a molded body by applying the same and sintering the molded body. 5. The method according to claim 4, wherein the binder is agar powder. 6. The binder is a carbohydrate having a gelling ability, such as carrageenan, alginic acid, polysaccharides such as pectin, glue and gelatin, starch and dextrin and derivatives thereof, natural pastes such as arabic gum and guar gum, polyvinyl alcohol and the like. The method according to claim 4, wherein the method is selected from a group of synthetic pastes. 7. The method according to claim 4, wherein the massive plate material of the composite material is formed by a compression molding method. 8. The method according to claim 4, wherein the massive plate material of the composite material is formed by an extrusion molding method. 9. The step of engraving the starting material with a shape that is inverted to the shape of a molded product to form a molded body is performed by directly engraving by a cutting program control in consideration of a sintering shrinkage rate based on a product drawing. The method for manufacturing a sintered mold for molding according to any one of claims 4 to 8, wherein: 10. The method according to claim 9, wherein the sintering shrinkage is 20%. 11. A mass of a composite plate made of a binder and a metal powder is SKD-61 (average particle size of 10 to 10% by weight).
15 μ) in powder agar (gel strength 1500)
g / cm ² ) of 2.60% and stearic acid of 0.78
%, And a powdered compound containing purified water by only 11.67%.
The method for producing a sintered mold for molding according to any one of 7 to 10.