JPS6011610B2 - Filling detection method in molding mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting whether a cavity is completely filled with molten resin when a molten synthetic resin material is injected into a mold.

Traditional filling detection methods have been by mechanical means or electrical sensing by placing electrical contacts in the cavity, or by applying pressure elements such as strain gauges.

These methods cannot be used for all molds because they require a detection rod and an electric circuit to be built into the metal. In particular, it has been extremely difficult to use it in each cavity of a mold that takes many small molded products. Furthermore, since fine adjustments are required within the mold, there are also restrictions on work, and if the fine adjustments are made incorrectly, there are drawbacks such as damage to the sensing and detecting section due to the pressure of the filled resin. This invention ensures the filling state of molten resin at the end of the cavity without using mechanical means such as a detection rod, electrical contacts, strain gauges, etc., and without the need for fine adjustment. It can be sensed to detect whether it is completely filled or not. This is an attempt to provide a new method. The present invention for the above-mentioned purpose is to dispose the air circuit at the resin injection terminal of the cavity in such a way that it can be cut off by the molten resin, regardless of the structure and size of the molding die, and to block the air circuit under the influence of the molten resin. By sensing the pressure change in the air circuit, it is possible to reliably detect whether or not the molten resin has reached the resin injection terminal of the cavity. In this method, detection can be performed simply by installing an air circuit at the end of the cavity that is farthest from the gate, so the device can be configured by connecting a part of the air circuit to the cavity or the end. It is only necessary to utilize the resin injection gap created in the above process and to shut off when the end portion or the resin injection gap is filled with molten resin, and no other special means is required. Therefore, the air circuit can distribute grain without being affected by the size and structure of the cavity, and in particular in multi-cavity molds, it can be installed in each cavity to prevent the short shot phenomenon. can be used. The present invention will be explained in detail below using the illustrated apparatus.

1 in the figure is a mold with 4 cavities, each cavity 2, 2...
is communicated by Runner 3.

In addition, an air circuit 6 is provided at the resin injection terminal farthest from the gates 4, 4... of each cavity 2, 2..., with the resin injection gap 5 extending outward forming a part of the passage. . This air circuit 6, as shown in FIGS. 2 and 3,
One side la of the mold 1 is provided with an air inflow passage 6a serving as an outgoing path and an air outflow passage 6b serving as a return passage, both of which are connected via the resin injection gap 5. A hole 7 is bored in a portion corresponding to the resin injection gap 5 of la, an annular groove 8 is formed around the inner periphery of the hole, and a part of the air outflow path 6b formed in the hole is connected to the annular groove 8.

In addition, inside the hole is a cylinder 9 whose outer diameter is slightly smaller and whose upper inner wall is slightly larger, and a cylinder 9 is inserted inside the cylinder 9 to form a gap around it that will become an air inflow path 6a. An air circuit member consisting of a core 10 is inserted with iron, and the air inflow path 6a is connected to the resin injection gap 5, and the gap created between the outside of the cylinder upper part and the inside of the hole 7 is connected to the other air outflow path 6b. As a part, an air circuit 6 is formed. In addition, when an air circuit is provided in the resin injection terminal part of the cavity, the cavity itself is used as a part of the air circuit, and the resin injection gap 5 is
is not necessary.

Also, the air circuit can be arranged across both molds.
There is no particular limitation to placing grain in one mold. Therefore, the air circuit 6 at the resin injection terminal of each cavity 2, 2...
Until it flows into the air, both the inflow and outflow passages are closed and there is no change in the pressure there, but the molten resin 11 flows into the state shown in Figure 4, blocking the air inflow 6a and cutting off the air circuit. When this happens, the pressure on the air outlet path 6b side decreases,
A pressure difference occurs between the inflow and outflow passages.

Therefore, the pressure in the air circuit 6 is set constant in advance, a minute pressure gauge is guided to the air outlet path 6b side, the pressure is constantly sensed, the pressure change is immediately sensed, and the pressure is converted into an electric signal to completely electrically complete the process. Detect filling. As described above, this invention detects whether or not the air circuit is completely filled by blocking the air circuit provided at the resin injection end of the cavity with the molten resin. can be reliably detected.

In addition, since the molten resin itself acts as a factor for pressure changes, there are no malfunctions and fewer breakdowns. Furthermore, since pressure gauges and electric circuits can be placed outside the mold, safety is easier than when they are installed inside the mold, and there is no risk of short circuits or electric shocks, and it can be used in any cavity.
It has the advantage of being applicable not only to detecting short shots, but also to controlling the operation of the injection ram.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate the filling detection method according to the present invention, and FIG. 1 is a plan view of the mold, FIG. 2 is a schematic vertical sectional view of the cavity portion, and FIG. 3 is an air circuit portion. FIG. 4 is a longitudinal sectional view of the air circuit portion in a state in which molten resin has flowed.

DESCRIPTION OF SYMBOLS 1... Mold, 2... Cavity, 5... Resin injection gap, 6... Air circuit, 6a... Air inflow path, 6b... Air outflow path, 11... Molten resin.

Blind 1 Figure 2 Figure 3 key 4 diagram

Claims (1)

[Claims] 1. An air circuit is provided at the resin injection terminal of the cavity in a state that it can be shut off by the molten resin, and the complete filling of the cavity with the molten resin is detected by sensing the pressure change in the air circuit caused by the shutoff. A method for detecting filling in a molding die, characterized by: