JPS6135922B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing elongated objects such as hands used in watches and the like.

Conventionally, pointers have been made one by one using, for example, a press using a metal material, which is very time consuming and difficult to process when secondary processing is required.

Therefore, the present invention aims to eliminate the above-mentioned drawbacks.
A large number of synthetic resin pointers are integrally molded at the same time. When molding multiple pointers from synthetic resin at the same time, the pointers are extremely thin;
It is desirable that the runner part where the resin flows is thicker.
It is known that during molding, the shrinkage rate of synthetic resin in the longitudinal direction varies depending on the thickness, and the large shrinkage of thick runners causes thin needles to warp. The present invention provides a manufacturing method and apparatus for simultaneously molding a large number of synthetic resin hands using thick runners, and in which warping of the hands does not occur.

In Figs. 1 to 3, two runners 1 and 2 are arranged in parallel to each other in a molded article A formed by injection molding, and the center connects the runners at approximately the center. Runner 3 is located. Between the two runners 1 and 2, there are a plurality of elongated pointers 4 extending in a direction parallel to the center runner 3'.
Both ends of ...... are connected at equal intervals.

The runners 1, 2 and the center runner 3 are thicker and wider than the pointers so as to ensure the flow of synthetic resin to each pointer 4, and the center runner 3 is particularly thick. . A gate part 3a and a tunnel gate part 3b are formed in the middle part of the center runner 3. In addition, a connecting shaft 4b has a hole 4c into which the tip of a drive shaft (not shown) is fitted on the lower surface of the center of the shaft support 4a of the pointer 4.
is hanging down.

As shown in FIGS. 4 and 5, a manufacturing apparatus for injection molding the molded article A comprises a cavity made up of a fixed mold 5 and a movable mold 6, and injection molding is performed by injecting synthetic resin. In other words, the fixed mold 5 includes the runners 1,
2, a center recess 9 for forming the center runner 3, and a plurality of pointer forming recesses 10 for forming the pointer 4. The center recess 9 communicates with the gate 11, and there is a tunnel gate 1 in the center recess 9.
2 is formed. Further, the movable mold 6 is provided with a pointer forming recess 13 which faces the pointer forming recess 10 and is narrower than the pointer forming recess 10, and a connecting shaft 4b forming recess 14. A hole 4c is provided in the connecting shaft forming recess 14.
A core pin 15 for forming a core pin 15 is protruded so as to be movable forward and backward. Further, in the recesses 7, 8 and the center recess 9, an undercut ejector pin 16 for attaching the molded product A to the movable mold 6 at the time of mold release is protruded so as to be freely advanced and retracted.

To manufacture a pointer, a cavity is constructed by bringing a movable mold 6 into contact with a fixed mold 5, and synthetic resin is injected through a gate 11. The synthetic resin quickly enters the pointer forming recesses 10 and 13 through the center recess 9, tunnel gate 12, and recesses 7 and 8, and is injection molded. When the movable mold 6 is separated from the fixed mold 5, the molded product A is separated while being attached to the movable mold by the ejector pin 16. At this time, the center runner 3 is separated from the movable mold by the tunnel gate 12 of the fixed mold 5. It is divided at part 3b. The core pin 15 and ejector pin 16 are moved back, and the molded product A is removed from the movable mold 6 by grasping the gate portion 3a of the center runner 3. When the molded product A has cooled down sufficiently, the thick center runner 3 parallel to the pointer
The shrinkage rate in the length direction is larger than that of the thin needle 4, but since the center runner 3 is divided by the tunnel gate as described above,
Large contractions of the center gate do not adversely affect the pointer. Since runners 1 and 2 are not parallel to the pointer, their shrinkage rates do not affect each other.

The molded product A taken out is transferred to secondary processing.
For example, to give the surface a glossy finish, metal may be sputtered using a sputtering machine, or metal may be vapor deposited using vapor deposition means. Then, if necessary, paint is applied, and after drying, both ends of the pointers 4 are cut off using a cutting machine and separated from the runners 1 and 2. During this cutting, the length of the pointer 4 is changed as appropriate depending on the watch being used.

As described above, according to the present invention, the thick center runner for supplying synthetic resin to a large number of pointers is divided during demolding, so deformation of the pointers due to differences in shrinkage rate is prevented, and the runners are connected to both ends of the pointers. Since the runner protects the pointer during secondary processing, secondary processing is easy, and a large number of points can be manufactured in one molding process, which helps reduce manufacturing costs.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which FIG. 1 is a front view of a molded product, FIG. 2 is an enlarged sectional view taken along the lines of FIG. 1, FIG. The figure is a sectional view of the mold at the position shown in FIG. 2, and FIG. 5 is a sectional view of the mold at the position shown in FIG. 3. A... Molded product, 1, 2... Runner, 3... Center runner, 4... Pointer, 5... Fixed mold, 6...
Movable type, 7, 8... recess, 9... central recess, 10
...Concavity for forming a pointer, 11...Gate, 12...
Tunnel gate, 14... recess for forming pointer connection shaft, 15... core pin, 16... ejector pin.

Claims (1)

[Claims] 1. Two runners arranged in parallel, a center runner that connects the two runners approximately at the center,
A molded product having a plurality of elongated objects supported between the two runners and substantially parallel to the center runner is integrally molded, and when the molded product is released, a tunnel gate is used to separate the center runner. After that, both ends of the elongated object are cut by the two runners. 2. Two recesses that become two runner parts arranged in parallel, a center recess that connects these two recesses at approximately the center and becomes a center runner part, and a center recess that connects to the two recesses. A fixed type including a plurality of elongate object forming recesses substantially parallel to the central recess, a tunnel gate provided in a part of the central recess, and a gate communicating with the central recess; An apparatus for producing a long and narrow article made of synthetic resin, comprising: a movable type having an ejector pin that protrudes into a recess of a book and can freely move forward and backward;