JP2002219550A - Manufacturing method for metal mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily manufacturing method of a mold without necessity of mechanical processing or electro-discharge forming in a manufacturing method of a mold. SOLUTION: A model 20 having a size determined by taking shrinkage rate into consideration in solidification is covered up to the half with sand 16 charged in a container, and then molten metal 28 is poured to produce one side metal mold 30 and subsequently the model 20 and the one side metal mold 30 are turned upside down and set again in the container. Then, molten metal 28 is poured to produce the other side metal mold 32. After the other side metal mold 32 is solidified, the model 20 is taken out of the molds 30, 32. In this way, the mold having the same cavity with the model 20 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold manufacturing method capable of forming a mold without performing machining or the like.

[0002]

2. Description of the Related Art In the prior art, when a mold is manufactured, an operation of cutting a metal block as a mold material by electric discharge machining or machining to form a molded product into an uneven shape is performed.

[0003]

When a mold is manufactured by the former electric discharge machining, there is a disadvantage that the manufacturing cost is increased and the product price is increased. In the case of manufacturing a mold by machining the latter metal block, it is necessary to complicate the NC program in order to obtain highly accurate dimensions. Therefore, there are drawbacks in that it takes a lot of processing time and cost to manufacture the mold, and the cast product becomes expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a metal mold which can significantly reduce the manufacturing time of the metal mold, suppress the manufacturing cost, achieve high accuracy, and reduce the product price. I do.

[0005]

According to the present invention, there is provided a mold manufacturing method for forming a mold in a mold frame, the method comprising: filling the mold frame with sand coated thereon. And a step of setting the existing product coated with a thickness in consideration of the amount of shrinkage after solidification in the sand, and a step of pouring the molten metal by closing the mold frame with a lid member forming a gate. After the molten metal is solidified, removing one of the molds formed by solidification of the molten metal from the mold frame, removing the sand from the mold frame, and removing the mold and the existing product. Inverting and setting the mold frame again, closing the mold frame with the lid member and pouring the molten metal again, and after the molten metal is solidified, the other is formed by solidification of the molten metal. Removing the mold from the mold frame; Rannahli, characterized in that to obtain a mold having the existing product substantially the same cavity the one mold and by the other mold.

According to the present invention, since the mold is manufactured by transferring the shape of the existing product, the manufacturing time of the mold and the manufacturing cost can be reduced.

Further, the present invention relates to a method for manufacturing a mold for molding a mold in a mold frame, wherein a step of filling the mold frame with sand coated thereon and a shrinkage amount after solidification of the molten metal are considered in advance. Place a sand model of size in the sand,
A step of pouring the molten metal by closing the mold frame with a lid member forming a gate, and a step of taking out one mold formed by solidification of the molten metal from the mold frame after the molten metal is solidified, A step of removing the sand from the flask, a step of reversing the mold and the existing product and setting it again in the flask, and a step of closing the flask with the lid member and pouring the molten metal again. And, after the molten metal is solidified, removing the other mold formed by solidification of the molten metal from the mold frame. The one mold and the other mold are substantially similar to the existing product. It is characterized in that a mold having the same cavity is obtained.

According to the present invention, when there is no product cast from the existing mold, a sand mold model that is substantially the same as the product is used. In this case, the size of the sand mold model becomes a desired size in a molded product obtained by taking into account the shrinkage due to solidification of the molten metal.

In the above invention, an existing product or a sand mold model may be set in the flask before the step of filling the coated sand in the flask. On the other hand, depending on the shape of the existing product or the sand mold model, the pre-filled sand is filled into the mold frame to about half the height of the existing product or the sand mold model, and then the existing product or the sand mold model is set in the mold frame. Then, the coated sand may be filled again. In the former case, depending on the shape, the sand may not sufficiently reach below the existing product or the sand mold model.

[0010] In the above invention, the coating material may be properly used depending on the type of the existing product. When the existing product is an aluminum alloy, it is preferable to use a mixture of a ceramic filler and aluminum powder, and when using an iron-based material, it is preferable to use a ceramic filler. This is because the product easily fits into the surface of the existing product and the existing product can be easily removed from the mold after the molding.

Further, in the above invention, it is preferable that a cooling pipe is cast into the mold frame before pouring the molten metal. The cooling pipe can be used to cool the molten metal at the time of molding, and after the molding, the molten metal for forming the molded article is cooled by the casting pipe through the mold. can do.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a mold manufacturing method according to the present invention will be described in detail below.

In the method for manufacturing a mold according to the present embodiment,
First, a container 10 composed of a flask with an open top is prepared. This container 10 has a bottom plate 12 as shown in FIG.
And four side plates 14a erected on the edge of the bottom plate 12.
To 14d. The bottom plate 12 and the four side plates 14a to 14d are separable. The sand 16 solidified by using glass as a binder is filled into the container 10 configured as described above to about half of its depth.

On the other hand, a model 20 is prepared in advance. As the model 20, for example, an existing product that is a molded product can be adopted. According to the present embodiment, when an existing mold is deteriorated due to long-term use, the mold can be duplicated by using an existing product formed in advance with the mold as it is. That is, a product manufactured using a mold having the same cavity shape as the mold to be produced is employed as it is. On the other hand, when an existing product is not used as the model 20, it is more preferable that the material of the model 20 has a melting point higher than that of the metal to be melted. In the present embodiment, when an existing product is not used, for example, iron or aluminum is used as a material.

Next, the coating process will be described. In this step, as shown in FIG.
Is coated with a coating material 22 by any method such as thermal spraying, crystal formation, and application. The coating material 22 is composed of a main coating material 22a and Kirako (mica powder) 22b. First, the main coating material 22a is coated on the entire model 20 first. The main coating material 22a is preferably prepared by dissolving powder of kaolin, talc, alumina, zirconia or the like to an appropriate concentration with about 5% by weight of water glass, and adding about 2% by weight of boric acid thereto. When the model 20 is an iron-based material, a ceramic-based coating material or the like may be used.
Usually, when the main coating material 22a is covered, the surface roughness is about 100 to 200S, and the surface may be slightly rough. FIG. 2 schematically shows a slightly rough surface by triangular protrusions. Therefore, in the present embodiment, Kirako 22b is coated on main coating material 22a as described above. This is because when the Kirako 22b is coated, the surface roughness becomes 30S or less, and a smooth surface is obtained. However, if surface roughness is not a problem for existing products, the Kirako 2
The coating of 2b may be omitted.

If the difference in the coefficient of thermal expansion between the constituent material of the model 20 and the coating material 22 is large, as will be described later, when the molten metal is poured into the container 10 in which the model 20 is set, the temperature is increased. The coating material 22 may peel off due to the change. Therefore, by adding a powder made of the constituent material of the model 20 to the coating material 22, the difference in the coefficient of thermal expansion between the constituent material of the model 20 and the coating material 22 can be reduced, and the above-described separation phenomenon can be prevented. This can be prevented.

As shown in FIG. 2, the thickness t of the coating material 22 is desirably set to a thickness corresponding to the amount of contraction of the poured molten metal when it solidifies. The shrinkage can be determined from the physical properties of the molten metal and the shape of the model 20. By this treatment, a mold having desired dimensions is obtained after the molten metal solidifies. The coating material 22 is also effective for controlling defects such as glaring on the surface (defects generated in the casting, such as hot water boundaries and blow holes), and cooling rate adjustment. The model 20 covered with the coating material 22 is positioned on sand buried about half in the container 10, pressed and buried to about half its height (see FIG. 3).

As described above, in this embodiment, the container 1
The model 20 is pushed in so that about half of its height is buried in the sand 16 filled to about half in 0, but the sand 16 is filled so that the bottom surface of the model 20 contacts ( After fixing the model 20 coated with the coating material 22 in the container 10, the sand 16 is further filled until the lower half of the model 20 is almost completely covered. Is also good. This is because it may be difficult to make the sand 16 wrap around the bottom of the model 20.

Next, the upper end of the container 10 is connected to a gate 24a.
24b is closed with a lid member 26 made of a refractory material. In this case, the number of gates may be plural, for example, three or more, without limiting to two.
Therefore, a molten metal 28 made of a metal such as an aluminum alloy or a zinc alloy is poured from the gates 24a and 24b. Here, the reason why a molten metal such as an aluminum alloy or a zinc alloy is used is that the melting point is lower than that of cast iron, copper, brass or the like in preparing a mold, and therefore, the handling is easy. Also, because aluminum has good thermal conductivity, it has a short cure time at the time of casting, and further has the advantage that the molten metal solidifies in a short time, so that the structure of the material is dense and the mechanical properties are good.

After a lapse of a predetermined time, the molten metal 28 is cooled to room temperature and solidified to form one mold 30. On the other hand, the outer shape of the upper half of the model 20 is transferred to the mold 30 as a cavity shape. In the present embodiment, aluminum alloy AC2B (JIS H5202) was used as molten metal 28, and the melting temperature was about 640 ° C.

Next, the one mold 30 is taken out of the container 10. In this step, first, the four side plates 1
4a to 14d are separated, one mold 30 and the model 20 formed of the solidified molten metal 28 are extracted from the sand 16 and the sand 16 filled in the container 10 is removed.
(See FIG. 5).

Next, the four side plates 14a are attached to the bottom plate 12.
14d is erected again to form a box, and then the process of turning over the model 20 and mounting it in the container 10 is started. That is, both the mold 30 and the model 20 are turned upside down, and then set in the container 10 again. At this time, the lower side of the inverted model 20 is fitted into one of the molds 30,
The one mold 30 and the model 20 are in an integrated state (see FIG. 6). In this case, for the remaining half of the model 20, the other mold 32 is created through the same steps as in the case where one mold 30 is created. That is, the open upper end portion of the container 10 is closed by the lid member 26 made of refractory material in which the gates 24a and 24b are formed. These gates 2
A molten metal made of a molten metal 28, such as an aluminum alloy or a zinc alloy, which is the same as the material used when forming the one mold 30 from 4a and 24b is poured. After a lapse of a predetermined time, the melt solidifies and the other mold 32 is completed. That is, when the molten metal 28 is poured from the gates 24a and 24b, the other mold 32 compatible with the one mold 30 already completed is obtained. The other mold 32 thus obtained is separated from the side plates 14a to 14d constituting the container 10 from the bottom plate 12 and taken out together with the one mold 30 (see FIG. 8). After removing the one mold 30 from the other mold 32 and removing the model 20 from the other mold 32, the shape of the model 20 is the same as that of the model 20 by the one mold 30 and the other mold 32. A mold having the above cavity is obtained.

If it is difficult to remove the model 20 from the other mold 32, the knockout pins 40a, 40
b may be used (see FIG. 9). That is, holes 38a and 38b are formed in advance on one surface of the other mold 32, and knockout pins 40a and 40b are inserted into the holes 38a and 38b.
When the tip of the knockout pins 40a and 40b are flush with the peripheral surface of the model 20, a cavity corresponding to the model 20 is obtained in the other mold 32. Such knockout pins 40a, 40b are connected to the other mold 32.
The model 20 and the other mold 32 are separated by energizing after completion of the process.

As described above, in the mold manufacturing method according to the present embodiment, the molds 30 and 32 for manufacturing products having the same outer shape are created using the model 20. Therefore, a mold can be easily and inexpensively manufactured.

When a product is not used as the model 20 or when there is no product as the model 20, a new sand mold model may be created with predetermined sand. In this case, if a sand mold having a size corresponding to a thickness corresponding to shrinkage of the molten metal after cooling is created in advance, the coating treatment of the coating material 22 as described above can be omitted.

A molten metal 28 of a metal such as an aluminum alloy or a zinc alloy is supplied from the gates 24a and 24b to the container 1.
When the molten metal is poured into the inside of the container 10, the refrigerant may be held in the upper part of the container 10 by the cooling pipe 41, and the refrigerant may be supplied from the cooling pipe 41. When the coolant is water, it can be rapidly solidified while circulating water in the cooling pipe 41 at the stage of solidification of the molten metal 28, so that a mold having a dense material structure can be formed. Here, the cooling pipes 41, 41 are preferably cast into the mold in both the step of creating one mold and the step of creating the other mold. This is because the refrigerant can be supplied uniformly. Further, the cooling pipes 41, 41 cast in this way can be used as a tool for cooling the mold after the mold is completed.

Here, one experimental example will be described. In this experimental example, the coating material 2 was used in the above-described coating process.
2 was confirmed. FIG. 13 shows an experimental model used in this experimental example. FIG. 1 shows the results of the experimental example.
4 to 16.

As shown in FIG. 13, this experimental model has a rectangular parallelepiped having a width A, a length B and a relatively low height, and a convex portion having a length C and a relatively low height. Shape. In this experimental model, the width A was set to 80.4 mm, the length B was set to 131.0 mm, and the length C was set to 81.0 mm. This experimental model was applied to the present embodiment to produce a mold and a material as a final product.

FIG. 14 shows the measured values of the dimensions of the width A portion. Each bar graph shows, in order from the left, the experimental model dimensions, the dimensions after coating the coating material 22, the dimensions of the prepared mold,
These are the dimensions of the mold at the time of casting and the dimensions of the raw material as the final product. Similarly, FIG. 15 shows the measured values of the length B portion, and FIG. 16 shows the measured values of the length C portion.

Referring to FIG. 14, in the portion of width A, the dimension after coating the coating material 22 with respect to the experimental model is 1 mm larger. Therefore, 80.4 + 1.0 = 81.4 [mm].

Then, the prepared mold shrinks by 0.6 mm. Further, when a material is prepared using the mold, the material is stretched by 0.2 mm at the time of casting, and the finished material contracts by 0.6 mm. Therefore, the dimension of the width A portion of the material is a minute width dA when viewed from the dimension after coating the coating material 22.
= 1.0 mm, and 81.4-dA = 80.4 [mm].

The shrinkage ratio is dA / 80.4 = 12.4 × 10 ^-3 .

FIG. 15 shows the result regarding the length B portion, and the meaning and arrangement order of the bar graph are the same as those in FIG. As for the length B portion, the dimension after coating the coating material 22 is 1.3 mm larger than that of the experimental model. Therefore, 131.0 + 1.3 = 132.3 [mm]. Here, the dimension of the length B portion of the material is a minute width dB = 1.2 m as viewed from the dimension after coating the coating material 22.
m, and 132.3-dB = 131.1 [mm]. Therefore, the shrinkage ratio is dB / 131.1 = 9.2 × 10 ⁻³ .

FIG. 16 shows the result for the length C portion, and the meaning and the arrangement order of the bar graph are the same as those in FIG. As for the length C, the dimension after coating with the coating material 22 is 1.2 mm larger than that of the experimental model. Therefore, 81.0 + 1.2 = 82.2 [mm]. The length C of the material is the size of the coating material 22
Is shrunk by a minute width dC = 1.0 mm as viewed from the dimensions after coating, and 82.2−dC = 81.2 [mm]. Therefore, the shrinkage ratio is dB / 81.2 = 12.3 × 10 ⁻³ .

From the above results, it can be seen that the contraction rate differs depending on the total length of the width A, the length B, and the length C of the model 20.
Further, the longer the predetermined part of the model 20 is, the lower the contraction rate is, and the shorter the predetermined part is, the higher the contraction rate is. When actually applied to the present embodiment, the thickness t of the coating material 22 may be determined by referring to the dA, dB, dC, and the like.

However, in this experimental example, the temperature of the metal in the solid-liquid coexistence state and the temperature of the molten metal at the time of casting were measured at predetermined experimental temperatures. It is desirable to determine the value in consideration of the rate and the like.

When the upper half and the lower half of the model 20 are coated with the coating material 22, it is preferable to divide the required shrinkage into two equal parts and cover both sides.

On the other hand, when the coating material 22 is not used, the dimensions of the model 20 may be determined in consideration of the shrinkage ratio in advance.

[0039]

As described above, according to the mold manufacturing method of the present invention, when there is already a product, the thickness of the coating material is added to the existing product in consideration of the shrinkage ratio when the molten metal solidifies. Cover above. For this reason, a mold in which the finished size of the product is the same as the original product is obtained, which is preferable. If there is no existing product, a mold for producing a product of desired dimensions can be obtained by designing and molding a model by adding the amount of shrinkage during cooling and solidification in advance. After all, according to the present invention, a mold can be manufactured without using machining techniques such as machining and electric discharge machining. As a result, the manufacturing period of the mold is significantly reduced as compared with machining and electric discharge machining, and the manufacturing cost is also reduced. Furthermore, since the thickness of the coating material and the size of the sand mold model are determined in consideration of the shrinkage rate at the time of solidification of the molten metal, a highly accurate mold can be easily and inexpensively manufactured.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view of a step of placing a model in a container in a step of creating one mold.

FIG. 2 is a partially sectional explanatory view of a coating material coated on a model surface.

FIG. 3 is an explanatory longitudinal sectional view of a step of producing one mold.

FIG. 4 is an explanatory longitudinal sectional view showing a state in which a molten metal is solidified in producing one mold.

FIG. 5 is a perspective explanatory view of a step of taking out the one mold and a model in producing one mold.

FIG. 6 is an explanatory perspective view of a step of placing one mold and a model inverted in the creation of the other mold in a container.

FIG. 7 is an explanatory longitudinal sectional view of a step of producing the other mold.

FIG. 8 is an explanatory longitudinal sectional view of a step in which a molten metal is solidified to form the other mold.

FIG. 9 is a partially cutaway perspective view showing a state in which a model is taken out from the other mold with a knockout pin at the stage when both molds are created.

FIG. 10 is a partially longitudinal sectional exploded perspective view of a step of separating a model from a mold using a knockout pin.

FIG. 11 is an explanatory longitudinal sectional view of a step of casting a cooling pipe.

FIG. 12 is an explanatory longitudinal sectional view showing a state where a cooling pipe is cast.

FIG. 13 is a perspective explanatory view of an experimental model used in an experimental example.

FIG. 14 is an explanatory diagram of an experimental result regarding a width A portion of the experimental model.

FIG. 15 is an explanatory diagram of an experimental result regarding a length B portion of an experimental model.

FIG. 16 is an explanatory diagram of an experimental result regarding a length C portion of an experimental model.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Container 12 ... Bottom plate 14a-14d ... Side plate 16 ... Sand 20 ... Model 22 ... Coating material 22a ... Main coating material 22b ... Kirako 24a, 24b ... Gate 28 ... Molten metal 30 ... One mold 32 ... The other mold 38a, 38b: Hole 40a, 40b: Knockout pin 41: Cooling pipe 42: Holder

Continued on the front page (72) Inventor Akio Kawase 1-10-1 Shinsayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (72) Inventor Kiyokatsu Kato 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. In-house (72) Inventor Toshiharu Morita 1-10-1 Shinsayama, Sayama-shi, Saitama F-term (reference) in Honda Engineering Co., Ltd. 4E093 FC07

Claims (4)

[Claims] 1. A method for manufacturing a mold for molding a mold in a mold frame, wherein a step of filling the mold frame with sand coated thereon, and wherein the coating is applied in a thickness in consideration of the amount of shrinkage after solidification. Setting the existing product in the sand, closing the mold frame with a lid member forming a gate, and pouring the molten metal; after the molten metal is solidified, formed by solidifying the molten metal. Removing one of the molds from the flask, removing the sand from the flask, reversing the mold and the existing product and setting the mold again in the flask, Closing the lid with the lid member and pouring the molten metal again; and after the molten metal is solidified, removing the other mold formed by solidification of the molten metal from the mold frame. With the mold and the other mold Mold manufacturing method characterized by obtaining a mold having a serial existing product substantially the same cavity. 2. A method for manufacturing a mold for molding a mold in a mold frame, comprising: filling the mold frame with sand coated thereon; and a sand mold having a size in consideration of the amount of shrinkage of the molten metal after solidification in advance. Setting a model in the sand, closing the mold frame with a lid member forming a gate, and pouring the molten metal; and after the molten metal is solidified, one of the molds formed by solidification of the molten metal. Removing the sand from the flask, removing the sand from the flask, reversing the mold and the existing product, and setting the mold again on the flask, and removing the flask with the lid member. Closing and pouring the molten metal again, and after the molten metal is solidified, removing the other mold formed by solidification of the molten metal from the mold frame. Abbreviated to the existing product by the other mold Mold manufacturing method characterized by obtaining a mold having one cavity. 3. The method according to claim 1, further comprising a step of setting the existing product or the sand mold model in the flask before the step of filling the coated sand in the flask. Characteristic mold manufacturing method. 4. The method of claim 1 or 2, wherein the step of filling the coated sand in the flask comprises filling the sand to half the height of the existing product or sand mold model, and then filling the sand. A method for manufacturing a mold, comprising a step of setting a product or a sand mold model in a mold frame and then embedding the existing product or sand mold model with the sand.