JPH0242429Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a mold for use in an injection molding machine for plastic materials such as rubber, plastic, etc.

"Prior Art" In general, an injection mold consists of a sprue, a runner, a gate, a cavity, and a protrusion mechanism for the molded product, and the relative positions of the mold, that is, the male mold 1 and the female mold 2 of the pin gate type, are controlled. To determine this, guide pins 3, 3, . . . are fitted into approximately four corners in parallel with the moving direction of the mold, as shown in FIGS. 5 and 6.

A receiving hole 4 is formed in the movable mold plate 6 of one of the molds to match the diameter of the guide pin 3, and a guide pin bush 5 is attached to the receiving hole 4.

Reference numeral 7 is a cavity, 8 is a fixed side mounting plate, and 9 is a movable mounting plate.

However, with a mold with this structure, no trouble will occur if there is no difference in temperature between the upper and lower molds, but if one side is heated and the other is at room temperature or cooled, a temperature difference will occur between the upper and lower molds. The expansion of the mold due to the temperature difference makes it impossible to match the guide pins 3, 3... and the bushes 5, 5, etc., and the runner part is removed from the mold each time and disposed of, so the material of the runner part is Loss is also one of the reasons for high costs.

In particular, when making a large number of dissimilar material molded products (rubber) made of A material (rubber) and B material (rubber) as shown in Fig. 7 A and B, the side gate method (see Fig. 8) is used. When material A is vulcanized,
Since the runner parts are vulcanized at the same time, the upper mold 11 and the lower mold 12 are opened across the parting line (PL), and the vulcanized runner part 13 is removed.
Next, the lower mold 12 is moved and combined with another upper mold 11' (see FIG. 9), and the B material rubber is filled and molded in the second mold.

However, like the pin gate method above, the upper and lower molds 1
Because one mold expands due to the temperature difference between 1' and 12, it has a defect that makes it impossible to match the guide bush and guide pin of the other mold.

14 is a heater that heats one mold to about 170 degrees Celsius; 15 is a hole for hot oil or cooling water that warms or cools the other mold to a temperature in the range of 0 degrees to 100 degrees C; 35 is an insulating material.

In addition, in order to simplify the installation of the mold, it is stated on page 26 of Industrial Examination Standards [2]-25-96 that the mounting hole should be made into a U-groove. Because the shape of the guide pin is unclear,
It is difficult to match the shape with the U groove.

``Problem that the invention aims to solve'' In order to prevent trouble between the guide pin and the bush due to the temperature difference between the molds caused by external factors such as heating or cooling of one side of the mold, the mold The object of the present invention is to form a bottomed square groove or a square bottomed notch at a predetermined location, thereby ensuring that the molds always match and eliminating material loss.

"Means for solving the problem" A guide pin is provided in the cross direction from the center of the mold, a bottomed square groove or a square bottomed notch is formed on the movable side template side corresponding to the guide pin, An injection molding mold that uses a rectangular guide pin in the groove for positioning, so that the expansion and contraction caused by the difference in mold temperature is averaged in the radial direction, making it possible to match the upper and lower molds even if the sizes of the upper and lower molds change. The purpose is to provide a model.

"Function" Since square grooves or square cuts are formed in the movable side template from the center in the cross direction, even if the movable side template expands due to external factors, the expanded portion will be replaced by the bottomed square groove or square cut. Since it is released through the bottomed notch of the mold and at the same time expands uniformly in the radial direction, there is no misalignment between the bottomed square groove and the square guide pin, and the upper and lower molds can be smoothly matched.

"Example" A preferred example of the present invention will be described below based on the drawings.

FIGS. 1 and 2 are examples of the application of the guide pin of the present invention to a single-cavity mold.

Reference numeral 16 denotes a movable mold plate, and the mold plate 16 is arranged in a straight line 17, 1 in the cross direction from the center O of the mold as shown in FIG.
8, and bottomed square grooves or square bottomed cuts 19 to 22 of the required depth are provided on the straight lines 17 and 18.
Formed in several places.

23 to 26 are rectangular guide pins attached to the fixed side template 27, and the lower ends 28 of the guide pins 23 to 26 are
.about.31 are made to match the widths of the bottomed square grooves or square bottomed notches 19 to 22 within a slidable range.

32 is the cavity, 33 is the fixed side mounting plate,
34 is a movable side mounting plate.

Next, the dissimilar material molded product (rubber) and the same molded product as shown in FIG. The filled molten rubber is not vulcanized and only the A material rubber in the lower mold 12 is vulcanized and molded, but its upper surface remains unvulcanized, and in this state, as shown in FIG. Since the lower mold 12 is moved and combined with another upper mold 11' to perform vulcanization molding of the B material rubber, the unvulcanized portion on the upper surface of the A material rubber is also vulcanized and bonded at this time.

Note that since the runner portion 36 of the upper mold is in an unvulcanized state, it can be used continuously.

"Effects" Since the movable side template of the mold of the present invention has a groove or bottomed notch formed in the cross direction from the center, even if the movable side template expands due to external factors such as heat, The expanded portion escapes in the radial direction through the groove,
At the same time, because it expands uniformly in the radial direction, there is no misalignment with the guide pins of the stationary mold plate, and mold matching is performed smoothly.

In particular, problems with mold matching can be avoided when double molding is required, such as in the case of small push buttons.

In addition, unlike molded products made of different materials, the runner part of the A material rubber is kept in an unvulcanized state during the first molding process, so there is no material loss. Extremely practical.

[Brief explanation of the drawing]

Figure 1 shows the mold of the present invention, Figure 2 is a cross-sectional plan view taken along the line A-A, Figure 2 is a cross-sectional side view taken along the line B-B in Figure 1, and Figures 3 and 4 show two types of multi-cavity molds. A sectional view showing the molding process of a molded product made of different materials, FIG. 5 is a known mold,
Fig. 6 is a cross-sectional plan view taken along line C-C, and Fig. 6 is Fig. 5 D-
A sectional side view taken along line D, FIGS. 7A and 7B are a sectional view and a plan view of a molded product made of different materials, and FIGS. 8 to 9 are sectional views showing the process of molding a multi-piece molded product made of different materials. 19-22: Groove or notch, 23-26: Guide pin.

Claims (1)

[Scope of utility model registration request] One movable side template 16 has straight lines 17 and 18 in the cross direction from the center O of the template 16, and the straight line 1
7 and 18 are formed with a bottomed square groove or square bottomed cuts 19 to 22 of a required depth from the end face toward the center O, so that the expansion in the radial direction is formed in the bottomed square groove or square bottomed notch 19 to 22. While letting it escape through the square bottomed notch, the lower ends 28 to 31 of the square guide pins 23 to 26 attached to the other stationary template 27 are slid into the one bottomed square groove or the square bottomed notch. An injection mold characterized by: