JPS61118219A - Molding method of narrow width groove for making electrodeposite locally on surface of nonconductive article - Google Patents

Abstract

PURPOSE:To enable quite easy molding of a V-shaped groove whose width is narrow, by narrowing an annular protrusion in a tongue-piece-like state which has been filled in an injection molding process at the time of a mold breaking process. CONSTITUTION:An annular V-shaped groove 3 is constituted of a horizontal plane 3a extending in the direction meeting at about right angles with a shaft center 4 of a small hole 2 and an inverted conical surface 3b extending upward slantwise from a circumferential wall of a large diameter hole 1 and coinciding the the horizontal plane 3a. The inside of a mold is filled completely with resin and the inside of the annular V-shaped groove 3 is also filled completely with the resin by applying appropriate pressure and temperature to the inside of the mold at an appropriate speed for an appropriate period of time, in an injection molding process. When the mold is broken completely after the mold has passed through a cooling process, it becomes a final product ejection process. A V-shaped protrusion forming a V-shaped groove, whose opening part is slightly wide, filled within the annular V-shaped groove 3 in the injection molding process is narrowed in order at the time of completion of breaking of the mold and a V-shaped groove whose opening is extremely narrow is formed.

Description

Detailed Description of the Invention (Industrial Field Related to the Invention) This invention forms narrow grooves to be provided in a non-conductive article when locally electrodepositing the surface of a non-conductive article such as synthetic toilet fat. It is about the method.

(Prior Art) One method of locally electrodepositing the surface of a non-conductive article is
It is described in Japanese Patent Publication No. 45-37843,
This method can be summarized as follows. In Figure 6,
For example, a shows a cross-section of a notch with a cutting angle of α and a depth of 2. A non-conductive article with such a notch is coated with a uniform layer inside the notch a by electroless plating as shown in Fig. 7. When plating with an electroplating bath, the metal C at the sharp internal corners will be dissolved in the electrolyte and the current density in such areas will be too small to electrodeposit the metal. Since the current is thus cut off at this point, only the left surface of the notch a connected to the power supply is coated with a metal layer d, as shown in FIG.

That is what it is.

Such a notch a has a cutting depth Ω and a cutting angle α
It is difficult to select the notch, it is undesirable if the angle α is too large, and it is undesirable if the depth β is too shallow, and it is not easy to form such a notch.

(Problems to be Solved by the Invention) The present invention makes it possible to simultaneously mold the notch, which is essential in the above-mentioned electrodeposition method, when molding the non-conductive article, thereby facilitating the molding of the notch, and furthermore, making it possible to mold the notch at the same time when molding the non-conductive article. The aim is to reduce costs.

(Solution Means of the Invention) A mold for injection molding includes a large diameter hole, a small diameter hole concentric with the large diameter hole, and an annular V-shaped groove provided between the large diameter hole and the small diameter hole, and the annular V-shaped groove is provided between the large diameter hole and the small diameter hole. The shaped groove is composed of a horizontal surface extending from the circumferential wall of the small diameter hole in a direction substantially perpendicular to the axis, and an inverted conical surface extending obliquely upward from the circumferential wall of the large diameter hole and matching the horizontal surface. After injection molding a non-conductive resin inside the mold, when demolding from the large diameter hole side, the annular protrusion filling the annular V-shaped groove is forcibly demolded from the large diameter hole of the mold to remove the annular protrusion. It is characterized by forming a narrow upwardly opening V-shaped notch between the small diameter part and the small diameter part.

(Example) FIG. 1 shows a portion of an injection mold used in the method of the present invention. This is a part of a mold for molding a columnar part A of a molded product (for example, an electric appliance knob) as shown in FIG. 2, and a square groove B is formed at the base of the columnar part A.

In FIG. 1, 1 is a large-diameter hole of the mold, 2 is a small-diameter hole, and 3 is an annular V-shaped groove between the large-diameter hole 1 and the small-diameter hole 2. The large diameter hole 1 and the small diameter hole 2 have a diameter difference of 2δ.

The V-shaped groove 3 is composed of a horizontal surface 3a extending substantially perpendicularly to the axis 4 of the small diameter hole 2, and an inverted conical surface 3b extending obliquely upward from the peripheral wall of the large diameter hole 1 and matching the horizontal surface 3a. .

The angle β between the horizontal surface 3a and the conical surface 3b is determined by the angle β between the horizontal surface 3a and the conical surface 3b. The shape and groove are selected to provide ideal localized electrodeposition.

Also, the diameters of the large diameter hole 1 and the small diameter hole 2, d, etc. are also selected at optimum values 1 depending on the type of resin, plating conditions, etc.

(Molding method) In the normal injection molding process, resin is completely filled into the mold by appropriate pressure, temperature, speed, and time during the injection process. After the first cooling process in which the inside of the annular V-shaped groove 3 is completely filled with resin, the mold opening process begins, and once the mold is completely opened,
This is the final product ejection process. The mold opening process will be illustrated and explained.

As shown in Fig. 1, the V-shaped protrusion that forms the V-shaped groove with a wide opening is filled into the annular V-shaped groove 3 during the injection molding process.
When the mold opening step is completed, the groove is narrowed as shown in FIGS. 3 to 5 to form a V-shaped groove with a very narrow opening.

(J! Akira's effect) The tongue-shaped annular protrusion filled in the injection molding process is squeezed during the mold opening process to form a narrow V-shaped groove, making molding extremely easy. can do. If similar grooves were to be made using other methods, not only would it be extremely difficult to manufacture the mold, but the cost and life of the mold would necessarily be inferior.

Since V-shaped grooves of such narrow width can be easily formed, localized electrodeposition can be carried out more easily and economically.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a mold for carrying out the method according to the invention. FIG. 2 is a sectional view of an article to which the method of the present invention is applied. 3 to 5 are explanatory diagrams of the molding method. 6 to 8 are explanatory diagrams of a known local electrodeposition method. In the figure: 1 Large diameter hole (in the mold) 2 Small diameter hole (in the mold) 3 (
(mold) Annular V-shaped groove 38 Horizontal surface 3b Inverted conical surface 4 Above the axis

Claims (1)

[Claims] A mold for injection molding consists of a large diameter hole, a small diameter hole concentric with the large diameter hole, and an annular V-shaped groove provided between the large diameter hole and the small diameter hole. The mold is composed of a horizontal surface extending from the peripheral wall in a direction substantially perpendicular to the axis, and an inverted conical surface extending obliquely upward from the peripheral wall of the large diameter hole and matching the horizontal surface. After injection molding, when demolding from the large diameter hole side, the annular protrusion filling the annular V-shaped groove is forcibly demolded from the large diameter hole of the mold, and the annular protrusion and the small diameter part are removed from the mold. A method of forming a narrow groove for locally electrodepositing a surface of a non-conductive article, forming a narrow upwardly opening V-shaped notch.