JPS58168539A - Injection molding method of synthetic resin product and device thereof - Google Patents

Abstract

PURPOSE:To make easily separable a product molded in a cavity from resin set in a runner and a gate part when they are released from a mold by a structure wherein the gate part comprising a convergently and circularly curved passage, which goes from the runner to the cavity around the parting face between a fixed mold and a movable mold, is provided in one of said molds. CONSTITUTION:In the titled injection molding method, whereby the runner 5, the gate 11, the cavity 4 and the like are formed on the parting face between the fixed mold and the movable mold and molten resin is injected from the runner 5 through the gate part into the cavity 4 and, after being cooled and set, the molds are open and a product in the cavity 4 and the resin set along the way to the cavity 4 are knocked-out by the ejection of pins 8 and 9 in order to be taken out, the gate part ranging from the runner 5 to the cavity 4 is provided in one (in the fixed mold in case of the Fig.) of the molds as the gate part comprising the convergently and circularly curved passage 10, which starts from the runner 5 formed on the parting face and advances detouring around the parting face and returns to the gate 11 provided on the parting face again.

Description

Detailed Description of the Invention This invention is an injection molding method created for the purpose of easily and automatically separating the product, launch, and gate in injection molding of synthetic resin products, thereby eliminating the labor of post-processing after molding. It is related to the device.

FIGS. 1 to 4 show the states of several types of conventionally implemented gates, with reference numeral 1 showing a fixed mold, 2 a fitting/removal mold, and 3 a bonding surface between both molds. In the plastic filled into these molds, 4 is a product, 5 is a runner, and 6 is a gate.

Figures 1 and 2 show the disposable boss type, and Figures 3 and 4 show the side gate type! l! In order to inject the raw material from the underside of the product, the disposable boss method shown in FIGS. 1 and 2 is used, and the disposable boss 7 must be cut and removed after molding. Note that 8 and 9 are protruding bottles. The connection between the sacrificial boss and the gate is automatically separated by the pin 8.

The runner 5 is naturally provided along the adhesive surface 3 of the mold in order to facilitate the removal of the hardened plastic, but the gate is not placed along the adhesive surface 3 in order to cut it. This is normal and leaves some scars. Especially if there is drawing process, try 1v. The fourth method is difficult because cutting marks tend to remain prominently on the bottom surface of the product, which is problematic when the bottom surface of the product is required to be the contact surface of a wig, and automatic cutting is difficult in both cases.

The present invention eliminates these drawbacks by providing an automatic gate.

An example of this is shown in FIGS. 5 and 6, in which the runner is detachable.

That is, bypassing the adhesive surface 3 of the mold at the gate part,
P) A tapered circular path 10 returning to the adhesive surface is formed, and the end of the circular path is projected as a gate 11 to a position slightly beyond the adhesive surface 3.

Note that reference numeral 12 indicates a nest provided to facilitate machining of the mold for the portion forming the circular curved path 10.

Since the present invention is configured as described above and is provided with a circular path 10 that detours around the adhesive surface of the potash mold, the gate 11 can be easily exposed to a part of the underside of the product, and the fitting/dismounting mold 2 can be detached from the mold. When ejecting the finished product using the ejecting bottles 8 and 9, which are the same as the ejecting bottles 8 and 9, there is
The resin is moved like a lever to apply strong tension to the gate 11 and cut the gate 11 from the product.

Therefore, there are effects such as no post-processing is required and a product without gate cut marks on the surface can be efficiently obtained.

Note that the gate 11 that protrudes beyond the adhesive surface 3 is normally 0.
．． It is about 3 to 0.5 fights.

[Brief explanation of the drawing]

FIGS. 1 to 4 are partial cross-sections of conventional molds. 5 and 6 are cross-sectional views showing embodiments of the present invention. 1 Fixed mold 2 Fitting/removal mold 3 Adhesive surface 4 Product 5 Runner 10 Circular path 11 Gate patent Applicant Fumiharu Matsumoto (1 person) Agent Patent attorney
Old 1) Tsuyoshi Keimina S['1

Claims (1)

[Scope of Claims] 1. In an injection molding method for synthetic resin products in which a fixed mold and a fit-and-remove mold have flat adhesive surfaces, and a runner is provided along the adhesive surface, the injection molding method bypasses the adhesive surface and re-inserts the adhesive surface. An injection molding method for synthetic resin products characterized by using the tapered end of a circular path that returns to the adhesive surface as a gate. 2. In an injection molding machine for synthetic resin products that has a flat adhesive surface between a fixed mold and a fitting/removable mold, and a runner is provided along the adhesive surface, the injection molding device bypasses the adhesive surface at the gate part and rejoins the adhesive surface. This is an injection molding device for synthetic resin products, which forms a tapered circular curved path that returns to its original position, and the terminal end of the curved line protrudes slightly beyond the bonding surface of the mold as a gate.