CN1003636B

CN1003636B - Method for manufacturing long-life resin mold for plastic injection

Info

Publication number: CN1003636B
Application number: CN86104403.7A
Authority: CN
Inventors: 陈铁铮
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-06-15
Filing date: 1986-06-15
Publication date: 1989-03-22
Also published as: CN86104403A

Abstract

本发明是一种使塑料注射用的树脂模具的寿命延长到近于钢模水平的方法，其特点是：型腔表面是在常温条件下形成的高熔点、高强度的金属薄层。因此制模时不受样件的熔点的限制。用模时塑料注射温度的高低，注射流的冲刷以及熔化状态塑料与树脂的作用等影响，故寿命可接近钢模水平，并保持了树脂模具的能一次成形、制模快、成本低、型腔表面高度精确等优点。The invention is a method for prolonging the service life of a resin mold used for plastic injection to the level close to that of a steel mold, and is characterized in that the surface of the mold cavity is a thin metal layer with a high melting point and high strength formed at normal temperature. Therefore, the molding is not limited by the melting point of the sample. When the mold is used, the plastic injection temperature is high or low, the injection flow is washed out, and the action of the molten plastic and the resin is affected, so the service life can be close to the level of the steel mold, and the resin mold can be formed at one time, the mold is fast, the cost is low, and the shape The cavity surface is highly accurate and so on.

Description

Method for manufacturing long-life resin mould for plastic injection

The present invention belongs to the field of mold making technology, and is especially method of prolonging the service life of resin mold for plastic injection to the level of steel mold.

It is known that resin molds commonly used at present are made of a high molecular synthetic resin such as epoxy resin, phenol resin, etc. in combination with a reinforcing agent and a casting, cold pressing or hot pressing. The mold has the following outstanding advantages: easy manufacture, high precision of the die cavity, quick forming and low cost. In particular, the resin mold can be used for one-step molding of a mold which has a complicated shape and a fine pattern and is difficult to machine. The cost is only one sixth of the traditional steel die, and the processing period can be shortened by ten times to dozens of times. However, when such a mold is used as a plastic injection mold, the life is low. The number of injections is only thousands of times abroad, but only one thousand times domestically. The main reasons for the low lifetime are two: one is that the resin itself has poor heat resistance, low thermal strength and small thermal conductivity. Secondly, because the resin and the plastic are both organic high molecular materials, the plastic in a molten state is easy to react with the resin at the plastic injection temperature to form adhesion or corrosion, so that fine patterns or smoothness on the surface of the cavity are damaged, and the service life is reduced. The range of applications is limited. At present, a new way for breaking through the technical difficulty is being sought at home and abroad.

The invention aims to provide a method for manufacturing a long-life resin mold for plastic injection. The mould made by said method not only retains all the advantages of original resin mould, but also overcomes the defect of short service life. The service life of the die can be close to the level of the traditional steel die.

In order to achieve the above object, a release agent is applied to the surface of a sample having an acceptable shape, size and pattern, and the temporarily unmolded portion is covered with wax at the parting surface. A thin metal layer with high melting point and high strength, such as copper, iron, nickel or chromium, with a thickness of 0.01-0.5 mm is formed on the surface of the intended molding part by vacuum evaporation or electroplating. The plated portion is then turned down and secured in a universal mold body and poured with a fluid resin mixed with a suitable metal powder. And taking out the sample after curing. And the other parts of the mould are manufactured in the same way. Because the surface of the cavity is a high-melting-point and high-strength metal layer, not only the molten plastic cannot be contacted with the resin and cannot be bonded or corroded, but also the temperature of the injection flow cannot reduce the strength of the surface of the cavity, so that the surface of the cavity cannot be damaged due to the washing of the injection flow. Thus, the purpose of the invention is achieved.

The realization of the requirement that a layer of high-melting-point and high-strength metal layer is formed on the surface of a cavity of a resin mold depends on that a sample piece is always in a normal temperature state in the vacuum evaporation or electroplating process. Only then, the melting point, burning point or thermal deformation of the sample material (such as wax, leather, etc.) is not limited. The resin is solidified and has high adhesion strength with the metal layer, and the resin is not easy to delaminate, and the metal powder is mixed in the resin, so that the strength is increased, and the heat conduction capability is enhanced. Therefore, the entire advantages of the resin mold are maintained, and the problem of a low life span for plastic injection is also thoroughly solved.

The accompanying drawings illustrate embodiments of the invention. Briefly described as follows:

the sample (1) is a leather-faced solid sphere with a diameter of phi 50 mm. Coating an anti-sticking agent on the whole surface, and covering the lower half part of the temporary non-molding die by using a wax with a die parting surface A-A as a boundary. The wax is made into the shape as shown in the attached drawing, and a pouring gate and a riser (7) are opened, a copper layer (2) with the thickness of about 0.05 mm is formed on the surface of an upper hemisphere by a vacuum evaporation method, the upper hemisphere is turned down and fixed on a proper position of a universal die body (3), and then a fluidized epoxy resin (4) which is uniformly stirred into iron powder is poured in from one of the ports (7) until the other port (7) is full. After curing, the sample is removed and the mold half is completed. The other mold half is made in the same way. The mold is a resin mold for injecting plastic solid balls, and the purpose of the invention is achieved.

[ 5 ] 6 ] is a stem for forming an injection hole and an exhaust hole.

Claims

1. A method for manufacturing a long-life resin mold for plastic injection molding, characterized in that a metal film is coated on the upper half of the parting surface of the sample, the sample is then turned over and fixed in a universal mold, and fluidized resin is poured into it. After solidification, the sample is removed and the mold for the remaining parts is manufactured in the same way.

2. The method according to claim 1, wherein a high-melting-point and high-strength metal film with a thickness of 0.01 to 0.5 mm is formed on the surface of the sample by vacuum evaporation or electroplating.

3. The method according to claim 1, wherein the fluid resin is mixed with metal powder such as copper, iron or chromium.