JPH028017A - Manufacture of mold with electroformed cavity - Google Patents

Abstract

PURPOSE:To prevent the deterioration of dimensional accuracy due to thermal deformation of a cavity and improve the strength and dimensional accuracy of a mold by a method wherein fasteners such as bolt, nut or the like are threadingly inserted via through holes, which are made on the mold, in the screw parts of connects, which are fixed to the cavity. CONSTITUTION:A cavity 3, which has finished the recess 1 of a mold 10 by electric discharge machining, is released from a matrix 2 after electric discharge machining and, after that, fitted into the recess 11 of the mold 10. Bolts 13 as fastener are threadingly inserted via through holes 12 to the female screw parts of connectors 5 so as to fix the cavity 3 to the mold 10. The pawl 14a of each press member 14, which is fixed to the mold 10 with a bolt 15, is urged to the engaging groove 16 of the cavity 3 in order to fix the cavity to the mold. In addition, in order to assist the fixation of the cavity 3 with the bolts 13, the press member 14 is fitted into recesses 17, which are made on the surface of the mold 10, so as not to project beyond a parting line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a mold having a cavity manufactured by depositing metal on the surface of a paste mold by electroforming.

(Prior Art) Recently, molds with cavities made by nickel electroforming, for example, have been used as molds for molding molded products that require dimensional accuracy or molded products with complicated shapes. The cavity manufactured in this way is usually integrated into a mold to form a mold, but for example, when manufacturing a mold by pouring molten zinc alloy into the back side of the cavity, the cavity itself is Since the cavity is heated to a temperature of about .degree. C. and close to the thermal composition deformation temperature of nickel electroformed products (430.degree. C. to 450.degree. C.), the cavity is thermally deformed and the dimensional accuracy and physical properties of the detonator deteriorate considerably.

(Problem to be solved by the invention +a> Therefore, a recess is formed on the surface of a steel mold by copying the cavity as a model, and after the cavity is fitted into the recess, the opening edge of the cavity is molded into the mold. In some cases, the cavity is fixed to the mold by being held down using a presser bolt bolted to the mold, thereby maintaining high dimensional accuracy of the cavity and maintaining good physical properties of the tube.
Although the concave parts created by copying machining can be finished, there is a drawback that it takes a long time to match the molds, and the cavities are usually 5 to IQ +
Since it is thin (n+e), it is difficult to firmly fix it even if you press the opening edge of the cavity with a presser.
If the cavity is heated to a high degree and the outer surface of the cavity is thermally deformed in the direction away from the recess of the mold, it is difficult to prevent this thermal deformation with the above-mentioned presser; There are circumstances in which it is not possible to adequately deal with deterioration in dimensional accuracy.

Therefore, an object of the present invention is to greatly shorten the time required for fitting the cavity and the mold, and to firmly attach the cavity to the mold to prevent deterioration of dimensional accuracy due to thermal deformation of the cavity as much as possible. The present invention proposes a method of manufacturing a mold having a cavity by electroforming, which can sufficiently increase the strength and dimensional accuracy of the mold.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a process of depositing metal on the surface of a mother mold manufactured by electroforming to create a cavity, and a process of manufacturing a cavity by welding or the like on the outer surface of the cavity. A process of fixing a connecting body having a threaded part and manufacturing a mold in which a concave part is formed by electric discharge machining using the cavity in which the connecting body is fixed as a master, and a through hole formed in this mold to correspond to the threaded part. The process is characterized by the step of fixing the cavity fitted in the recess to the mold by screwing a fastener such as a bolt or nut into the threaded part through the hole. .

(Function) According to the above-mentioned means, since the mold is matched with the mold by performing electric discharge machining using the cavity as a master, the mold matching time can be significantly shortened. The cavity is fixed to the mold by screwing a fastener such as a bolt or nut into the threaded portion of the mold through a through hole formed in the mold.
Deterioration of dimensional accuracy due to thermal deformation of the cavity can be prevented as much as possible, and the strength and dimensional accuracy of the mold can be sufficiently increased.

(Example) An example in which the present invention is applied to a mold used for injection molding of plastics will be described below with reference to the drawings. That is, a mold for injection molding usually consists of a pair of upper and lower molds that are divided into upper and lower halves at a parting line, and the upper mold 1 will be explained below.

In Fig. 2, reference numeral 2 is a mother mold for electroforming formed into a concavo-convex shape opposite to that of the cavity 3. The cavity 3 is manufactured by electrodepositing nickel to a predetermined thickness by electroforming. After electroforming, the cavity 3 has a female thread 4 at a predetermined location on its outer surface without releasing the mother mold 2.
A connecting body 5 made of nickel or steel that has been formed in advance is fixed by, for example, welding, and a build-up 6 is formed into a shape that can be cut out by applying nickel to the undercut portion 3a of the other outer surface by lava-forming metal spraying. (see FIG. 2(a)), and furthermore, nickel is deposited to a predetermined thickness on the entire outer surface of the cavity 3 except for the connecting body 5 by metal spraying to form a reinforcing layer 7 (see FIG. 2(b)). reference). Using the cavity 3 in which the reinforcing layer 7 has been formed in this way as a prototype, a female mold 8 is first formed from plaster (see FIG. 2(c)), and then a male mold 9 is further formed using this female mold 8 as a prototype (see FIG. 2(c)). (See Figure 2(d)). Reference numeral 10 denotes a mold manufactured by casting iron, aluminum, brass, etc. using this male mold 9 as a prototype, and the side surface of this mold has a shape that approximately matches the outer surface of the reinforcing layer 7 of the cavity 3 and the outer surface of the connecting body 5. A recess 11 is formed (see FIG. 2(e)). Now, in this mold 10, after forming a through hole 12 using a drilling machine or the like in a portion corresponding to the female threaded portion 4 of the connecting body 5, the recessed portion 11 is subjected to electric discharge machining using the cavity 3 in which the reinforcing layer 7 has been formed as a master. The outer shape of the cavity 3 is matched.

In this case, gold! ! 10 shrinks at a predetermined rate when cooled to room temperature after casting, so that the recess 11 forms the cavity 3.
Since the outer diameter is slightly smaller than the outer diameter of , a finishing margin (approximately 0.5 to 1 degree) suitable for electrical discharge machining can be obtained.

Now, the cavity 3 whose recess 11 of the mold 10 has been finished by electric discharge machining is released from the mother mold 2 after the electric discharge machining, and the cavity 3 is fitted into the recess 11 of the mold 10. Reference numeral 13 denotes a bolt as a fastener, which is screwed into the female threaded portion 4 of the connecting body 5 through the through hole 12.
The cavity 3 is fixed to the mold 10 by this. Furthermore, the first
In the figure, reference numeral 14 denotes a presser member fixed to the mold 10 with bolts 15, the claw portion 14a of which is pressed into engagement groove 16 of the cavity 3. The holding member 14 is conventionally used exclusively for fixing the cavity 3, but in this embodiment, it is used to assist the fixing of the cavity 3 with the bolt 13, and is formed on the surface of the mold 10. It is fitted into the recessed part 17 so that it does not protrude beyond the parting line. In addition, the above-mentioned engagement groove 1
6 and the recess 17 may be formed in the cavity 3 and the mold 10, respectively, by machining before the cavity 3 is fitted into the recess 11.

According to the present invention, the undercut can be filled and the connecting body 5 can be filled! +) Since the mold is manufactured by casting using the first molded cavity 3 as a model, the cavity may be thermally deformed or the electroforming composition may deteriorate, as when zinc alloy is poured into the back side of the cavity. This does not occur, and since the cavity 3 in which the concave portion 11 of the mold 10 is not released from the mother mold 2 is used as a master for electrical discharge machining, the internal stress of the electroforming process is reduced after the cavity 3 is pierced. Even if distortion occurs due to the influence, by tightening the bolts 13, the outer periphery of the cavity 3 can be tightly fitted into the mold 10 against the distortion of the cavity 3, and dimensional accuracy can be significantly improved.

Furthermore, since the connecting body 5 can be attached to any part of the cavity 3, the bonding strength between the cavity 3 and the mold 10 can be significantly improved for large-sized cavities 3, and therefore the cavity 3 can be used for injection molding. Even if the cavity 3 is heated to a high temperature during the process, thermal deformation such as floating up from the recess 11 is reliably prevented.
Compared to the conventional structure in which the cavity is fixed only by the holding member 14 of this embodiment, the dimensional accuracy of the cavity 3 is improved by 111 times, making it possible to maintain high dimensional accuracy for a long period of time. can.

Furthermore, in the above embodiment, since the cavity 3 is used as a master for electrical discharge machining, the mold matching work is easier than in the conventional structure in which the concave portion is formed by profiling. Since the holes 12 are formed, the amount of machining can be reduced accordingly, and the machining time of electrical discharge machining can also be shortened.

[Effects of the Invention] As is clear from the above description, the present invention performs mold matching with the mold by performing electrical discharge machining using the cavity as a master, so that the mold matching time can be significantly shortened. This is because the cavity is fixed to the mold by screwing a fastener such as a bolt or nut into the threaded part of the connecting body fixed to the cavity through a through hole formed in the mold. , it is possible to prevent deterioration of dimensional accuracy due to thermal deformation of the cavity as much as possible, and the strength and dimensional accuracy of the mold can be sufficiently increased, which is an excellent effect.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional view, and FIGS. 2(a) to 2(e) are longitudinal sectional views showing the manufacturing process. In the drawing, 1 is the upper mold, 3 is the cavity, 4 is the female thread, and 5
1 is a connecting body, 10 is a mold, 11 is a recess, 12 is a through hole, 1
3 is a bolt (fastener). Applicant Ikegami Kaken Kogyo Co., Ltd.

Claims (1)

[Claims] 1. The process of depositing metal on the surface of the mother mold by electroforming to produce a cavity, and fixing a connecting body with a threaded part to the outer surface of this cavity by welding etc., and creating a cavity with the connected body fixed. A process of manufacturing a mold in which a recess is formed by electrical discharge machining as a master, and inserting a fastener such as a bolt or nut into the threaded part of the mold through a through hole formed to correspond to the threaded part. A method for manufacturing a mold having a cavity by electroforming, comprising the step of fixing the cavity fitted in the recess to the mold by screwing into the mold.