JPH082534B2 - Method of manufacturing electroformed mold - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an electroforming mold.

(Prior Art) As shown in FIGS. 9 and 10, the conventional method for manufacturing an electroformed mold is, for example, a model 1 for manufacturing a mold formed into a product shape with wax, wood, gypsum, or plastic.
On the surface of, the silver layer is projected by the silver mirror reaction to give conductivity, and then a plating layer (die body) 2 of nickel or copper is formed to an average thickness of about 8 mm by electroforming. . Next, the back side of the plated layer 2 is used as a backing block 3 and solidified with resin cement or resin-containing aluminum particles. A water passage pipe 4 for temperature control is embedded in the lining block 3. Then, when the backing block 3 is solidified, the model 1 is peeled off, so that the model 1
It is possible to manufacture an electroformed mold in which the surface shape of is copied to the front surface.

However, the electroformed mold produced by the above-mentioned conventional method has a low mold clamping pressure (usually 5 to 5) because the plating layer 2 is lined with resin cement or resin-containing aluminum particles.
20 kg / cm ² ) It has sufficient strength as a mold for reaction injection molding (RIM), but high mold clamping pressure (usually 200 to 400 kg).
(/ cm ² ) As a mold used for injection molding, compression molding, etc., there is a problem that it cannot be used due to insufficient pressure resistance.

In order to solve such a problem, instead of the conventional backing block 3 made of resin cement or resin-containing aluminum particles,
It is possible to form a backing block by pouring molten aluminum alloy or zinc alloy behind the plated layer.

However, in such a method, a large number of irregularities that are unrelated to the shape of the model are formed on the back surface of the plating layer, but it is very difficult to penetrate the molten metal into every irregularity, and air voids are generated. It is unavoidable that the air voids remain, and when the molding pressure is applied, the air voids are depressed. Further, in this conventional method, there is a problem that the plating layer is exposed to the high-temperature molten metal and softens to cause thermal deformation, which deteriorates the dimensional accuracy of the cavity.

Further, in the above-mentioned conventional method, the plating layer may be distorted due to contraction when the molten metal is cooled and solidified, resulting in dimensional variation and peeling.

Therefore, conventionally, in order to increase the strength of the backing block 3, the method shown in FIGS. 11 to 13 has been adopted.

This conventional method, as shown in FIG.
After being formed thicker than necessary, a large number of irregularities 2a irrelevant to the shape of the model 1 formed on the back surface of the plating layer 2 are formed.
As shown in FIG. 12, is cut by a cutting machine 5 or the like that operates as shown by the arrow to make the back surface of the plating layer 2 a smooth surface 2b having no unevenness. Further, as shown in FIG. 13, a lining block 3 having a front surface which is in close contact with the smooth surface 2b.
Is manufactured by casting or cutting with an aluminum alloy or a zinc alloy in a separate process. Next, the electroplating mold was manufactured by fitting the plating layer 2 into the backing block 3 and fixing it with screws 6 or the like.

However, in this conventional method, since the plating layer 2 is formed to be thick and the plating layer 2 is cut, the electroforming process requires a large amount of time and a large amount of time, resulting in reduced productivity. There is also a lot of waste.
Further, also in the production of the backing block 3, high precision is required, which causes a problem of increasing the processing cost.

(Problems to be Solved by the Invention) In the conventional electroformed mold shown in FIG. 11 to FIG. 13,
Since the lining block was made of resin cement,
There was a problem of low pressure resistance. Also, in the method of forming a backing block by directly pouring a molten aluminum alloy or the like to the back of the plating layer (die body), the molten aluminum alloy or the like is at a high temperature, so that the dimensional accuracy may deteriorate due to thermal deformation or the like. There is a problem that the plating layer is peeled off, and an air void is generated due to the unevenness on the back surface of the plating layer, which causes a depression. Furthermore, by a method of forming a thick plating layer, cutting the back surface of this plating layer, and fitting and fixing the plating layer to a backing block made of an aluminum alloy or the like whose front surface is formed to match this back surface, There was a problem of increasing man-hours and costs.

Therefore, the method (not known) shown in FIGS. 1 to 4 has been proposed by the present inventor. In this method, a thin mold body 12 having a mold cavity surface 12a on its front surface is formed on the surface of a mold manufacturing model 11 by electroforming, and tin, bismuth, cadmium, lead, zinc, indium, and antimony are formed. A low-melting-point alloy 18 composed of at least two members selected from the metal group in a molten state is formed on the rear surface 12b of the main mold body 12 formed on the surface of the mold manufacturing model 11, and the main mold body in the frame body 17 The backing block 13 which is introduced on the back surface 12b of 12 and is made of a material selected from the group of metal materials of aluminum alloy, zinc alloy and steel and has a front surface having a shape similar to the back surface of the mold body 12 is shown in FIG. As shown in FIG. 5, the front surface 13a is pressed until it comes into contact with the back surface 12b of the mold body 12, and at this time, the tips of the convex and concave portions on the back surface 12b of the mold body 12 and the front surface 13a of the backing block 13 are brought into contact with each other. Contact with the back surface 12d of the back surface 12b of the mold body 12 A facing surface of the front 13a of the block 13 and the abutment surface 13d abuts. At this time, the excess molten low melting point alloy 18 is pressed by the backing block 13,
Through the through hole 13c of the backing block 13, the negative of the die body 12 and the backing block 13 overflows to the outside. In this state, the backing block 13 is formed by a method of hardening the low melting point alloy 18.
The front surface 13a and the back surface 12b of the mold body 12 are integrally coupled via a thin layer of the low melting point alloy 18 in a positional relationship facing each other, and further at an appropriate position on the back surface 12b of the mold body 12. The formed contact surface 12d is in close contact with the contact surface 13d of the backing block 13.

Then, in the mold body 12, an appropriate portion of the uneven back surface 12b is previously cut by a cutting machine or the like to form a contact surface 12d. Further, the backing block 13 has a front surface 13
A through hole (13c) is formed so as to penetrate from a to the back surface (13b) on the opposite side, and a water pipe (14) located near the front surface (13a) for circulating cooling water is buried. Further, as shown in FIG. 2, the model 11 having the mold body 12 formed on the surface is fitted into the frame body 17 mounted on the base plate 15 by the clamp 16 or the like so as to face the mold body 12. The model 11 and the backing block 13 are surrounded by a frame body 17, and the backing block 13 is fixed to the frame body 17 by bolts 22 or the like.

In this method, the backing block 13 that lines the die body 12 as the plating layer from the back surface 12b is made of an aluminum alloy, a zinc alloy, or steel to increase the pressure resistance and to perform mold clamping in injection molding or compression molding. Withstands pressure, the shape of the back surface 12b of the mold body 12 and the backing block 1
Even if the shape of the front surface 13a of 3 does not completely match, the mold body 12 and the backing block 13 are surely coupled to each other, and thermal deformation of the mold body 12 can be prevented. Further, at the time of molding, particularly the contact surface 12d formed at an appropriate place on the back surface 12b of the mold body 12 and the contact surface 13d of the backing block 13 which is in close contact with the contact surface 12d exert a mold clamping pressure. A low melting point alloy 1 that can be reliably received and is melted on the back surface 12b of the mold body 12.
After introducing 8, by pressing the backing block 13 until its front surface 13a abuts the back surface 12b of the mold body 12,
Excessive low melting point alloy 18 is caused to overflow from between the die body 12 and the backing block 13, and bubbles generated in the concave and convex portions on the back surface 12b of the die body 12 are compressed or crushed. Further, by leaving the mold body 12 fixed to the mold manufacturing model 11 in all the steps of manufacturing, it has an advantage of preventing deformation of the mold body due to pressing of the backing block 13. There is.

However, with this method, it is required to cut the specific surface of the back surface of the mold body on the surface of the model, on which a large number of irregularities are formed, with high processing accuracy, which requires time and labor for the processing and finishing process. It takes man-hours and becomes an obstacle to cost reduction. Further, the mold may be thermally deformed at the time of manufacturing, and there is a problem that the dimensional accuracy of the mold becomes low.

The present invention has been made in view of the above problems, and provides a method for manufacturing an electroformed mold that has high pressure resistance and accuracy, and that reduces man-hours and costs in manufacturing.

(Means for Solving the Problem) A method for manufacturing an electroformed mold according to the present invention according to claim 1 is such that a thin mold main body 12 is formed on the surface of a mold manufacturing model 11 by electroforming, and an aluminum alloy is used. , A zinc alloy, a backing block 13 having a front surface 13a made of a material selected from a metal material group of steel and having a shape similar to the back surface 12b shape of the mold body 12, the front surface 13a and the mold manufacturing model 11 A gap 21 is formed between the mold body 12 and the back surface 12b formed on the surface.
Hold and position, fill the gap 21 with oil 19,
After heating this oil 19, a low melting point alloy 18 made of at least two metals selected from the group consisting of tin, bismuth, cadmium, lead, zinc, indium and antimony is introduced into the gap 21 in a molten state, and the oil is added. The low melting point alloy 18 is hardened by substituting it with 19.

(Operation) In the method for manufacturing an electroformed mold according to the first aspect of the present invention, before the molten low melting point alloy 18 is introduced, the back face 12b of the mold body 12 and the front face 13a of the backing block 13 are held with the gap 21. Position the backing block 13 facing each other, and place the oil in the gap 21.
After filling 19 and heating, the low melting point alloy 18 is introduced into the gap 21 in a molten state and replaced with the oil 19, so that the backing block 13 can be accurately positioned in advance with respect to the mold body 12. In addition, generation of air voids and thermal deformation of the mold can be prevented, and dimensional accuracy is improved.

(Example) An example of a method for manufacturing an electroformed mold of the present invention will be described with reference to FIGS. 5 to 7.

As shown in FIG. 5 (a), a thin plating layer (die body) 12 of nickel or copper or the like having an average of about 8 mm is formed on the surface of the die manufacturing model 11 by electroforming. The front surface of the plating layer 12 joined to the mold manufacturing model 11 becomes a mold cavity surface 12a, but the back surface 12b of the plating layer 12 has many irregularities unrelated to the shape of the mold manufacturing model 11. Has been formed.

Further, the backing block 13 made of a material selected from a group of die materials of aluminum alloy, zinc alloy, and steel is manufactured by casting or the like. The shape of the front surface 13a of this backing block 13 is a shape that is substantially the reverse of the shape of the surface of the mold manufacturing model 11, and is similar to the shape that is the reverse of the shape of the back surface 12b of the plating layer 12, and , Backing block 13,
A through hole 13c is formed so as to penetrate from the front surface 13a to the back surface 13b on the opposite side, and a water pipe 14 for circulating cooling water is buried near the front surface 13a. And
Frame attached to the base plate 15 by the clamp 16
Model for mold production with plating layer 12 formed on the surface in 17
11 is inserted with the plated layer 12 facing upward.

Then, a gap 21 of several mm to several cm is provided between the back surface 12b of the plating layer 12 formed on the surface of the mold manufacturing model 11 and the front surface 13a of the backing block 13 facing the back surface 12b. , The backing block 13 is positioned above the mold manufacturing model 11, and the periphery of the mold manufacturing model 11 and the backing block 13 is surrounded by a frame body 17, and the backing block 13 is bolted to the frame body 17. Fix it with 22, etc. When the backing block 13 is fixed above the plating layer 12 formed on the surface of the mold manufacturing model 11, the plating layer
The number between the back 12b of 12 and the front 13a of the backing block 13
It is manufactured by performing rough processing so that a gap 21 of mm to several cm is formed. The contact surface 12d is not limited to the smooth surface shown in the figure, but may be a curved surface or a surface having a step.

Then, the boiling point is 180 ~ from the through hole 13c which is a sprue previously formed through the central portion or the outer peripheral portion of the backing block 13.
An oil 19 such as edible oil or mineral oil at 200 ° C. is injected, and this oil 19 is heated by a heater 24 to about 120 to 140 ° C.
As shown in FIG. 5 (b), if the oil 19 is circulated and heated via a stop valve 25 provided outside, a heating container 27 having a heater 26, a return pipe 28, and a pump 29, the temperature is further increased. A uniform temperature distribution can be obtained.

Next, as shown in FIG. 6, a low melting point alloy 18 containing tin, bismuth, cadmium and the like as a main component and having a melting point of about 140 ° C. is melted from a heating container 31 having a heater 30 through a dropping valve 32. Drop into the through hole 13c. This low melting point alloy 18 is
Gently descends through the oil 19 and keeps the temperature
Fill 21 in order from the lowest point. At this time, oil 19
Since (specific gravity 0.9) is remarkably lighter than the low melting point alloy 18 (specific gravity 7.5 to 9), it is easily replaced by the low melting point alloy 18 and overflows from the through hole 13c. In addition, the oil 1
A drain valve 33 for opening and closing the overflow channel 9 is provided.
In this way, if the low melting point alloy 18 is poured until the upper limit of the through hole 13c is reached, all the oil 19 in the gap 21 will be melted in the low melting point alloy 18
Is replaced by.

Then, the gap 21 between the plating layer 12 and the backing block 13
After the low melting point alloy 18 filled in is hardened, the frame 17 is removed and the mold manufacturing model 11 is peeled off to obtain the electroformed mold shown in FIG.

 Next, the operation of this embodiment will be described.

Model for mold making before injection of molten low melting point alloy 18
Above the plating layer 12 formed on the surface of 11, a low melting point alloy
Since the backing block 13 is fixed with a gap 21 into which 18 should be injected, with reference to the cavity surface 12a of the plating layer 12,
The backing block 13 can be correctly orientated in advance, and therefore the working and finishing process of the mold, which requires high accuracy, can be greatly simplified.

In addition, since the low melting point alloy 18 is introduced into the gap 21 through the heated oil 19, air voids cannot be formed in the uneven portion of the back surface 12b of the plating layer 12, and the rapid cooling of the low melting point alloy 18 is prevented. It is possible to prevent thermal deformation of the mold and improve dimensional accuracy.

If the low melting point alloy 18 is directly injected at atmospheric pressure without replacing the oil 19, as shown in FIG.
Air voids 34 are formed in the uneven portion of the back surface 12b of the.

Further, the low melting point alloy 18 is a metal material of the other die members of the plating layer 12 and the backing block 13, that is, nickel,
Since it has a low melting point unlike copper, zinc, aluminum alloys, etc., it can be easily separated from other mold members, recovered, and reused.

Further, since the electroformed mold produced in this manner has the plating layer 12 lined with the backing block 13 made of a high-strength aluminum alloy, zinc alloy, or steel, it has a high compressive strength and a high clamping force. It can also be used for high injection molding and compression molding.

Further, the low melting point alloy 18 containing tin, bismuth, cadmium, etc. as the main component can be injected in a molten state at a lower temperature than the aluminum alloy, the zinc alloy, etc., which are the materials of the backing block 13, so that the heat of the plating layer 12 can be reduced. Deformation, distortion, and peeling can be prevented, and the accuracy of the cavity surface 12a is maintained.

In addition, since the cavity surface 12a of the plating layer 12 can be bonded to the mold manufacturing model 11 in all the manufacturing steps, even if the backing block 13 is pressed,
The accuracy of the cavity surface 12a is reliably maintained.

The low melting point alloy 18 is tin, bismuth, cadmium,
It may be made of at least two selected from the group of metals of lead, zinc, indium, and antimony. For example, cadmium has a problem of oxidative deterioration, so tin and bismuth are more preferable.

By the way, if the melting point of the low melting point alloy 18 is 90 ° C. or lower,
There is a high risk that it will be softened by heat during molding and its rigidity will decrease, and it is not very practical. On the other hand, when the temperature is 180 ° C. or higher, thermal deformation and distortion of the plated layer 12 during manufacturing cannot be ignored. Therefore, the melting point of the low melting point alloy 18 is preferably 90 to 180 ° C.

(Effects of the Invention) According to the present invention, before the introduction of the molten low melting point alloy, the backing block is positioned so that the front surface of the backing block is opposed to the back surface of the mold body with a gap therebetween. The backing block can be accurately orientated beforehand based on the cavity surface of the main body, and the mold body and the backing block are a thin layer of a low melting point alloy containing tin, bismuth, cadmium, lead, etc. as the main components. Since it is integrally connected via the back side, it is not necessary to cut the back surface of the mold body formed on the surface of the model with a large number of irregularities in the manufacturing process, and the back surface whose front surface is opposed to this back surface The block is not required to have high machining accuracy, and therefore, the machining finishing process of the mold, which requires high accuracy, can be simplified, and the man-hour and cost can be further reduced. Further, after filling the gap with oil and heating it, the low melting point alloy is introduced into the gap and replaced with oil, so that generation of air voids and thermal deformation of the die can be prevented, and dimensional accuracy can be improved. .

Then, since the thin die main body which is the plating layer is lined with the lining block made of aluminum alloy, zinc alloy or steel, the pressure resistance of the electroformed die is improved. Moreover, since the low melting point alloy can be introduced in a molten state at a low temperature, it is possible to prevent thermal deformation, distortion and peeling of the main body. Furthermore, since the contact surface formed on the back surface of the mold body and the facing surface of the backing block are in close contact with each other at appropriate points, the pressure resistance of the mold is further improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a mold body is formed on the surface of a mold manufacturing model showing a manufacturing process of a method for manufacturing an electroformed mold which is a premise of the present invention, and FIG. FIG. 3 is a schematic cross-sectional view showing a state in which a mold manufacturing model in which a mold body is formed is fitted in a frame body. FIG. 3 is the same as above, but a low melting point alloy is introduced on the back surface of the mold body and the backing block is fitted in the frame body. FIG. 4 is a schematic cross-sectional view showing the situation, FIG. 4 is a schematic cross-sectional view showing a state in which the backing block is pressed against the mold body, and FIG. 5 (a) is a mold showing an embodiment of a method for manufacturing an electroformed mold of the present invention. FIG. 5 (b) is a schematic sectional view showing a step of heating the oil filled in the gap between the mold body and the backing block, FIG. 5 (b) is a schematic sectional view showing a modified example of the same step of heating the oil, and FIG. Fig. 5 shows the process of dropping the molten low melting point alloy from the state shown in Fig. 5 (a) and replacing it with oil. A schematic cross-sectional view, FIG. 7 is a schematic cross-sectional view of the electroformed mold manufactured in the same as above, FIG. 8 is a schematic cross-sectional view showing the formation state of air voids when the method of replacing oil is not adopted, and FIG. 9 is A schematic cross-sectional view showing a state in which a mold body is formed on the surface of a mold manufacturing model showing an example of a conventional method for manufacturing an electroformed mold, and FIG. 10 shows a state in which the mold body is lined with resin cement or the like. 11 is a schematic sectional view showing
The figure is a schematic cross-sectional view showing a state in which a mold body is formed on the surface of a mold manufacturing model showing another example of a conventional electroformed mold manufacturing method, and FIG. 12 is the same as the above, but cutting the back surface of the mold body. FIG. 13 is a schematic cross-sectional view showing the situation, and FIG. 13 is a schematic cross-sectional view showing a state in which a backing block made of an aluminum alloy or the like is bonded to the mold body. 11 …… Mold manufacturing model, 12 …… Plating layer (mold body), 12b …… Back of the plating layer of the mold body, 13 …… Backing block, 13a …… Front side of backing block, 18 …… Low Melting point alloy, 19 ... oil, 21 ... gap.

Front page continuation (72) Inventor Yoshinori Goto 218 Aoshima-cho, Fuji-shi, Shizuoka Nihon Plast Co., Ltd. (56) References JP 62-198408 (JP, A)

Claims (1)

[Claims] 1. A process of forming a thin mold main body on the surface of a mold manufacturing model by electroforming, the mold main body comprising a substance selected from a group of metal materials of aluminum alloy, zinc alloy, and steel. And placing a backing block having a front surface having a shape similar to the back surface of the mold with a gap between the front surface and the back surface of the mold body formed on the surface of the mold manufacturing model, Filling the gap with oil and heating, and introducing a low-melting point alloy containing at least two metals selected from the group consisting of tin, bismuth, cadmium, lead, zinc, indium and antimony in a molten state into the gap. And a step of substituting the oil to harden the low melting point alloy, the method for producing an electroformed mold.