JPH02151342A - Production of core and electrodeposition bellows using this core - Google Patents

Abstract

PURPOSE:To obtain the core which is transferred with the surface state of a casting as it is by heating a low melting alloy material to the temp. lower than its m. p. temp. and compressing and forging the material with the compressive strength much smaller than the compressive strength at ordinary temp. to obtain a master pattern core, and heating this core to the m. p. or above in a casting mold, then cooling the core. CONSTITUTION:The low melting alloy material 1 is heated to the temp. lower by about 5 to 70 deg.C than its m. p. temp. and is compressed and forged in this state to form the 3rd master pattern core 4. This master pattern core 4 is disposed into a casting cavity 22 of the casting mold 21 for the core of a segmental die type made into a bellows shape. The master pattern core 4 disposed in such mold is heated to the m. p. temp. of the low melting alloy or above to melt at least the surface of the master pattern core 4. The casting mold 21 for the core is then cooled down to the m. p. temp. of the low melting alloy or below and the molding is parted from the casting mold 21, by which the bellows core 5 is obtd. The bellows core is subjected to chemical plating or electroplating to form a thin metallic film 8 and the core is heated to the temp. above the m. p. of the low melting alloy and below the m. p. of the thin metallic film 8 to dissolve away only the bellows core 5. The metallic bellows having high quality is easily produced in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a core and a method for manufacturing an electrodeposited bellows using the core, and in particular, a method for manufacturing a core using a low melting point alloy and the method for manufacturing an electrodeposited bellows using the core. The present invention relates to a method for producing electrodeposited bellows using a core.

[Prior art and problem to be solved 8] Conventionally, electroplated bellows are manufactured by cutting an aluminum material to form a bellows core, and then applying electrolytic polishing to the surface of this aluminum bellows core to a desired thickness. After a metal thin film is formed on the aluminum bellows core, only the aluminum bellows core is dissolved and removed using a dissolving agent such as an alkaline solution.

In such a conventional method of manufacturing electrodeposited bellows,
Since an aluminum material is used as the bellows core and the core made of this aluminum material is dissolved in a dissolving agent, the aluminum material cannot be recovered, which increases the manufacturing cost of electrodeposited bellows. When aluminum material is melted with a dissolving agent, hydrogen and oxygen gases are generated and there is a risk of explosion if there is insufficient ventilation. It takes time to process and it is difficult to form the surface of the bellows core smoothly, so the manufacturing efficiency of electrodeposited bellows is poor, and the surface of the electrodeposited bellows obtained is rough, making it difficult to achieve high quality. The problem was that it was not possible to obtain

The present invention solves the problems of the conventional products as described above, and uses a low melting point alloy as the core material, making it possible to manufacture high-quality cores inexpensively, safely, and easily. It is an object of the present invention to provide a method for manufacturing a core, and also to provide a method for manufacturing an electrodeposited bellows, which allows high-quality metal bellows to be obtained using the core.

[Means to solve the problem]

In order to achieve the above object, the core manufacturing method of the present invention compresses and/or forges a low melting point alloy material while heating it to a temperature 5 to 70 degrees Celsius lower than its melting point temperature, and produces a prototype core. After molding, this prototype core is placed in a casting cavity of a casting mold for cores, and the prototype core placed in this casting cavity is heated to a temperature higher than the melting point temperature of the low melting point alloy to form a mold. After melting at least the surface of the core, the core casting mold is cooled to a temperature below the melting point of the low melting point alloy, and the core casting mold is released from the core casting mold. The method for manufacturing bellows is to compress and/or forge a low melting point alloy material while heating it to a temperature 5 to 70°C lower than its melting point, form a prototype core, and then mold this prototype core into a bellows. disposed in a casting cavity of a split-type core casting mold having a shaped casting cavity, and heating the prototype core disposed within the casting cavity to a temperature higher than the melting point temperature of the low melting point alloy; After melting at least the surface of the prototype core, the core casting mold is cooled to below the melting point temperature of the low melting point alloy, and the mold is released from the core casting mold to obtain a bellows core. A thin metal film is formed on the surface of the bellows core by chemical plating or electrolytic plating, and then the bellows core with the thin metal film formed on the surface is heated to a temperature below the melting point temperature of the low melting point alloy and below the melting point temperature of the thin metal film. It has means for heating and melting and removing only the bellows core.

[Function] By employing the above-mentioned means, the present invention compresses and/or forges a solid low-melting point alloy material with a compressive strength significantly lower than that at room temperature to obtain a prototype core. By heating the prototype core in a casting mold, it is possible to produce a core that directly transfers the surface condition of the casting mold, and by using the bellows core obtained by this method, metal plating can be applied to the surface of the core. After applying this, only the core can be easily melted and removed by heating the whole to a temperature above the melting point of the low melting point alloy and below the plating metal.

〔Example〕

The low melting point alloy material used in the present invention is 70 to 2
Preferably, the alloy has a melting point of 50°C, and further contains tin (Sn), bismuth (Bi), lead (Pb), cadmium (Cd), zinc (Zn) and antimony (S).
It is preferable that it is an alloy containing 2 to 4 metal elements selected from the group b), for example, (1) B i
/Pb/Sn/Cd=50/26.7/13.3/
10 (melting point 70°C), (2) B i / P b
/ Cd -51,65/40.20/8.15 (melting point 91.5°C), (3) B i/S n = 57/43
(melting point 13B, 5°c), Pb/5n=38.1/6
1.9 (melting point 183°C), (5) Sn/Z
n = 91/9 (melting point 199°C), (6) P b
/S b=87. 5/12.5 (melting point 247°C) and the like.

Figure 1 shows the temperature dependence of the compressive strength of the above-mentioned low melting point alloy material, and shows the B of (3) above.
Three types of specimen alloys, i/S n alloy, (4) P b /S n alloy, and (5) Sn/Z n alloy, were tested under the following conditions, and the vertical axis represents the compressive strength (Kg).
-f/cd), and is a correlation diagram in which the horizontal axis is the ambient temperature (°C).

That is, a square bar ingot alloy material with a diameter L2.7 mm
A test specimen with a length of 25.4 mm was cut, and the temperature and compressive strength were changed as parameters, and a 0.2% offset value and a 2.5% deformation value were determined in accordance with ASTM. (Executed with 3 samples each)

From the results of this first test, the above B i / S n alloy material has a 2.5% deformation value of 550 (Kg ・f/cd) and a 0.2% offset value at room temperature (25"C). shows a compressive strength of 470 (Kg-f/cn), respectively, but at a temperature 70"C lower than the melting point (138,5°C), it shows a compressive strength of 330 (Kg-f/cn) and 275°C, respectively.
(Kg-r/ca>, and it turns out that the compressive strength is about 60% of that at room temperature. Furthermore, the closer it gets to the melting point, the smaller the compressive strength becomes.
'C At low temperature, the 2.5% deformation value is 150 (K g-
f/cd), 0. 2% offset direct is 125
(Kg - r/c4), and each has a compressive strength slightly less than 30% of that at room temperature.

Additionally, P b /S n alloy materials and S n /
In the case of Zn alloy materials, the melting point (18
At a temperature 70°C lower than 3°C, the 2.5% deformation value and 0.2% offset value are approximately 60% of room temperature, and at a temperature 5°C lower than the melting point, the 2.5% deformation value and 0. ．．
Each of the 2% offset values has a compressive strength slightly less than 30% of that at room temperature, and the latter has a 2.5% deformation value and 0.2% at a temperature 70°C lower than its melting point (199°C). Each of the offset values is about 60% of the room temperature, and at a temperature 5° C. lower than the melting point, the 2.5% deformation value and the 0.2% offset 4B each have a compressive strength slightly less than 30% of the room temperature.

In other words, it has been shown that the above-mentioned low-melting point alloy material can be deformed with a compressive strength that is significantly smaller than that at room temperature at temperatures below its melting point and close to its melting point. , it is possible to compress and/or forge a low melting point alloy material as a solid without completely melting it with a small compressive strength and form it into almost the desired core shape, and furthermore, this prototype core can be used as a core material. The casting mold is placed in the casting cavity of the casting mold, and the mold for the core is heated from the outside or the master core inside the casting mold is heated by high-frequency induction heating to melt at least the surface of the master core and melt the core. It has been discovered that since the core surface can be adapted to the casting mold and the surface roughness of the casting cavity can be completely transferred, a core having a desired surface roughness can be easily produced.

Embodiments of the present invention shown in the drawings will be described below.

Figure 2 (a) (b) (C) ~ Figure 5 (a) (b
) are diagrams illustrating the manufacturing process of the core according to the present invention.

In the method for manufacturing a core according to the present invention, first, a rod-shaped low melting point alloy material 1 is placed in an upper mold 1 as shown in FIG.
The low melting point alloy material 1 and the compression mold are placed in the molding cavity 13 of a compression mold consisting of a lower mold 1 and a lower mold 12, and the low melting point alloy material 1 and the compression mold are heated at a temperature of 5 to 70°C lower than the melting point temperature of the low melting point alloy. 1
Heat it up to a high temperature.

Next, as shown in FIG. 2(b), the upper mold 11 and the lower mold 12 are
After compression molding the low melting point alloy material l with a predetermined compressive strength, the compression mold is cooled to cool the low melting point alloy, and the molded product is released from the mold, as shown in Fig. 2 (C). A first prototype core 2 having the shape shown in is obtained.

Furthermore, the first prototype core 2 shown in FIG.
As shown in Figure (a), the first prototype core 2 and the compression mold are arranged in a molding cavity 16 of a compression mold consisting of an upper mold 14 and a lower mold 15, and the first prototype core 2 and the compression mold are made of a low melting point alloy. Heat to a temperature 5 to 70°C lower than the melting point of.

Next, as shown in FIG. 3(b), the upper mold 14 and the lower mold 15 are
After compression molding the first prototype core 2 with a predetermined compression strength, the compression mold is cooled to cool the low melting point alloy, and the molded product is released from the mold, as shown in FIG. A second prototype core 3 having a recess 3a formed in the center as shown in C) is obtained.

Subsequently, the second prototype core 3 obtained above was molded into a vertically split type molding type having a molding cavity 17 with bellows-shaped unevenness provided on the inner circumferential surface and open at the top, as shown in FIG. mold 1
8.18, and the second prototype core 3, the mold 18.18, and the mold 1 having a slightly larger diameter than the recess 3a of the second prototype core 3. Sun, 18
The ram 19 located above the ram 19 is heated to a temperature 5 to 70°C lower than the melting point temperature of the low melting point alloy.

Next, as shown in FIG. 4(b), the ram 19 is lowered and fitted into the recess 3a of the second prototype core 3 disposed in the molding cavity 17 of the mold 18.18. After expanding the concave portion 3a of the second prototype core 3 by applying a predetermined compressive strength from the inside of the core 3a to the outside in the radial direction and molding the outer peripheral surface into a bellows shape, the mold 18.18 and the ram 19 are The low melting point alloy is cooled, the ram 19 is moved upward, the mold 18.18 is opened to release the molded product, and the cylindrical jig 20 with one end closed is moved to the Insert it into the recess 4a formed by slightly expanding it with the ram 19 and
) A third prototype core 4 having bellows-like irregularities formed on the outer circumferential surface is obtained.

Next, the third prototype core 4 obtained above is shown in FIG.
As shown in a), a thin-walled split-type casting mold 21.21 has a smooth mirror-like surface and a casting cavity 22 with precise bellows-shaped unevenness and an open upper part.
It is arranged in the casting cavity 22 of.

Then, the prototype core 4 placed in this casting cavity 22 is
After melting at least the surface of the third prototype core 4 by heating from the outside of the casting mold 21 to a temperature higher than the melting point of the low melting point alloy by means such as hot air, an oil bath, or high-frequency induction heating, the casting mold 21.21 is cooled to below the melting point temperature and cast into mold 2.
I and 2I are opened and the molded product is released to obtain a bellows core 5 as shown in FIG. 5(1)).

As is clear from the correlation diagram shown in Part 1, the compressive strength of the low melting point alloy material during forming in each of the forming steps shown in Figures 2(a) to 4(C) above is normal temperature. The compressive strength may be about 30 to 60% of that of the low melting point alloy material.Furthermore, in the present invention, as shown in FIGS. The prototype core is heated to such an extent that at least its surface is melted to make the surface conform to the surface of the casting cavity 22, and the mirror-finished surface of the casting cavity 22 is completely transferred. The surface of the bellows core 5 can be formed into a smooth mirror surface.

In addition, in the above molding process, FIG. 4(a) (b3
By omitting the step (C) and not inserting the jig 20 and not forming bellows-like irregularities on the outer surface, the 31st
4 (Fig. 5 (a) ■) directly from the rough prototype core shown in bl.
) may be placed in a casting mold to heat the prototype core and melt the surface of the prototype core, but by including the process shown in the above example, the thermal efficiency of the subsequent steps can be improved. It is possible to significantly improve the

In addition, the casting mold 21.21 must be a split mold as in the above embodiment for those with undercuts such as the bellows core as described above, but for cores with no undercuts. In the case of casting, it is not necessary to use a split mold type.Furthermore, in the heating means for melting the surface of the prototype core disposed in the casting mold 21.21,
Materials such as metals with good heat conductivity are selected for the casting mold in the case of heating by ordinary hot air, oil bath, etc., and materials other than metal can be selected for the casting mold in the case of high-frequency induction heating.

Next, the process of electrolytic plating on the surface of the bellows core 5 obtained above will be explained.

First, the bellows core 5 is immersed in a plating solution 6 such as a nickel sulfate aqueous solution as shown in FIG. A current is passed between them for a predetermined period of time to form a metal thin film 8 of nickel or the like on the surface of the bellows core 5.

Next, the entire bellows core 5 with the metal thin film 8 formed on its surface as described above is heated to a temperature higher than the melting point temperature of the low melting point alloy and lower than the melting point temperature of the metal thin film 8, and only the bellows core 5 is melted and removed. By doing so, the metal bellows 9 can be obtained while leaving the metal thin film 8.

The surface of the metal bellows 9 manufactured as described above is
Since the mirror-like surface of the bellows core 5 is directly transferred, the finished surface is formed into a precise mirror-like surface, resulting in a high-quality metal bellows that cannot be formed with a machined aluminum core. You will be able to obtain

In addition, the metal material for electrolytic plating in the above examples is as follows:
There are no restrictions on the material as long as it has a higher melting point than the low melting point alloy material and does not form an alloy with the low melting point alloy material.

Further, the electrolytic plating in the above embodiments is not limited to this, and may be chemical plating or a combination of both.

[Effects of the Invention] Since the present invention is configured as described above, by heating the low melting point alloy material to a temperature 5 to 70'C lower than the melting point, it is possible to form a solid with a compressive strength significantly lower than that at room temperature. The low melting point alloy material can be formed into almost the desired core shape in its original state, and furthermore, at least the surface of the original core is finally melted inside the casting cavity of the casting mold, so that the casting of the casting mold can be performed easily. If the inside of the cavity is finished to a mirror finish, the mirror finish will be transferred directly to the core surface, ensuring a high quality core with a mirror finish, and will also improve work safety since molten liquid metal is not handled. In addition, after the surface of the bellows core is plated with metal, only the core can be easily melted and removed by heating the entire body to a predetermined temperature, making it a high-quality metal bellows with a mirror-finished surface. It has excellent effects such as being able to be easily and efficiently manufactured.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the compressive strength and temperature dependence of the low melting point alloy material used in the present invention, and Figure 2 (a) (bl (
C), Figure 3 (a) (b) (C), Figure 4 (a)
(b) (C) and Fig. 5 (a) are diagrams explaining the steps of the core manufacturing method according to the present invention, Fig. 6 is a process diagram of electrolytic plating on the surface of the core, and Fig. 7 is FIG. 6 is a sectional view of the core obtained on the surface with a metal thin film formed thereon, and FIG. 8 is a perspective view of the electrodeposited bellows obtained by removing only the core from the one in FIG. 1...Low melting point alloy material 2...First prototype core 3...Second prototype core 3a, 4a...Concavity 4... ...Third prototype core 5 ... Bellows core 6 ... Plating solution 7 ... Metal rod 8 ... Metal thin film 9 ... ... Electroplated bellows 11.14 ... Upper mold 12.15 ... Lower mold 13.16.17 ... Molding cavity 18 ...
・Forming mold 9...Ram 0...Jig...Casting mold 2...Casting cavity flute 2 Figure (b) (C) Figure 3 (b) Supervise 3 things (c) Figure 5 (b) Figure 4 (b) (C) Figure 61 Figure 7 Figure 8 'u'! % base

Claims (1)

[Scope of Claims] (1) The low melting point alloy material (1) is
After compressing and/or forging at a temperature lower than 70°C to form a prototype core (4), the prototype core (4) is
) for the core casting mold (21), and the casting cavity (22) of (21).
), and the prototype core (4) disposed in the casting cavity (22) is heated to a temperature higher than the melting point temperature of the low melting point alloy to melt at least the surface of the prototype core (4). After that, the core casting molds (21), (21) are cooled to below the melting point temperature of the low melting point alloy, and the molds are released from the core casting molds (21), (21). Core manufacturing method. (2) The low melting point alloy material (1) is
After compressing and/or forging at a temperature lower than 70°C to form a prototype core (4), the prototype core (4) is
) is a split-type core casting mold (21) having a bellows-shaped casting cavity (22), and the casting cavity (22) of (21) is
), and the prototype core (4) disposed in the casting cavity (22) is heated to a temperature higher than the melting point temperature of the low melting point alloy to melt at least the surface of the prototype core (4). After that, the core casting molds (21), (21) are cooled to below the melting point temperature of the low melting point alloy, and released from the core casting molds (21), (21) to form a bellows core ( 5) is obtained, and this bellows core (5) is subjected to chemical plating or electrolytic plating to form a metal thin film (8) on the surface of the bellows core (5).
), and then the bellows core (5) with the metal thin film (8) formed on the surface is heated above the melting point temperature of the low melting point alloy to below the melting point temperature of the metal thin film (8), to form the bellows core (5).
) is melted and removed.