JPH0211149Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a mold opening device with excellent durability for a primary mold upper mold having a triple structure and a vertically split mold that can be opened in a twin injection molding machine. It is something.

BACKGROUND ART A twin injection molding machine capable of two-color molding is known, which has two injection devices 2 and 4 and two sets of molds 6 and 8 as shown in FIG. There are two sets of molds, one for primary molding 6 and the other for finishing molding 8
Each mold consists of a pair of upper molds 10 and 20 and lower molds 18 and 22. The two lower molds have the same internal structure and are designed to be repeatedly reversed via a mold rotating plate 26, so that the combination of the two sets of molds can be alternately replaced. One of the two upper molds
The upper mold 10 for the next molding has a triple structure and is a vertically split mold that can be opened, and the upper mold for the primary molding is also opened in a predetermined order via a mold opening device. .

Hitherto, a press-fit engagement type device as shown in FIGS. 2a and 2b has been known as a mold opening device for the upper mold for primary molding. This involves inserting the engaging hand 40 having the groove 42 into the locking tool 44, fitting the groove with the pressing rod 46 of the locking tool, and pressing the thread joint 40 into place with the elastic force of the spring 50. This is how it was done. In addition, 48 in FIG. 2 is a piece to prevent the pressing rod from popping out. Therefore, when the mold is clamped and opened, the engagement hand 40 and the locking tool 44 are repeatedly inserted and withdrawn.

However, opening the upper mold for primary molding requires a pressure force that overcomes the motion resistance of the mold opening parts 12 and 14 in the upper mold, and because the required pressure force is large, each time the upper mold is inserted and pulled out, the injection molding machine A large impact force acts on the entire body to cause it to vibrate, and this vibration or impact often causes the engaging hand to break (break off) and become unusable. The frequency of breakage of the engaging hand is once every 1,000 to 2,000 mold closings or mold openings, which corresponds to an average of once per 24 hours of operation, and in some cases, the breakage occurs 2 to 3 times. There was quite a bit to do. It takes a lot of time to replace the broken engagement arm, which is a major cause of lower operating efficiency and production efficiency. In addition, the upper mold may not be opened or the upper mold may not be engaged due to the relative positional deviation in the vertical and horizontal directions between the upper mold and the lower mold due to the above-mentioned vibrations or shocks. Another drawback was that the joints often collided with the locking tools and were destroyed.

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks by employing a cross-engagement (hook engagement) system using a device consisting of hook-like engagement hands, and provides a device with excellent durability.

The present invention will be explained based on the drawings illustrating the invention.

As shown in FIG. 1, a twin injection molding machine to which the device of the present invention is applied has two injection devices 2 and 4 and two sets of molds 6 and 8. The two sets of molds include one for primary molding 6 and the other for final molding 8. Each mold has an upper mold 10, 2
0 and a lower mold 18, 22, the two lower molds have the same internal structure and are fixed in parallel to a mold rotary plate 26 mounted on a movable platen 24 so as to be reversible repeatedly. has been done. On the other hand, the two upper molds are fixed to a fixed plate 38. One of the upper molds 10 for primary forming is a vertically split mold with a triple structure that can be opened as shown in Fig. 3, and when it is pulled out to open the mold, the first mold The object 12 is guided by the guide pin 28 fixed to the second object 14, and the second object 14 is guided by the guide pin 32 fixed to the third object 16 in a predetermined order. When the guide pins 28 and 32 reach the ends, they come into contact with the stoppers 30 and 34 at the tips of the respective guide pins 28 and 32 and stop, so that the separation distance between the first and second sheets or the second and third sheets is a predetermined distance. It's summery. Therefore, specifically, in the upper mold for primary molding, the third piece 1
6 is fixed to the fixed plate 38.
Note that each guide pin and stopper is adapted to be accommodated in a hole provided in a corresponding mold portion when the mold is clamped.

The device of the present invention is assembled using steel hook-like engaging hands 52, 56 that cross-engage with each other at their respective hooks 54, 58, as shown in FIGS. 4 and 5, for example. That is, the hook-shaped engaging hands 52 are fixed to each side of the two lower molds, and the other engaging hand 56 is attached to the side of the first piece 12 from the lower mold side of the upper mold for primary molding. When opening the upper mold, the hook portion 54 of the engaging hand and the hook portion 5 of the engaging hand itself
8 are fixed at positions where they can be engaged crosswise. Note that the length of the hook-like engagement arm is determined from the distance between opposing surfaces of the upper mold and lower mold in the mold open state and the mounting position.

Molding of a target object using the above-mentioned twin injection molding machine is performed by a series of automated molding cycles consisting of the following steps.

In other words, mold clamping → simultaneous injection of resin on the primary side and finishing side → opening of the upper mold and lower mold followed by opening of the upper mold for primary molding → reversal of the lower mold → final product from the lower mold This cycle consists of the steps of taking out the runner sprue portion of the primary molded body from the upper mold for primary molding and then clamping the mold. At the stage of opening the upper and lower molds, the runner part of the primary molded object in the primary molding die is held by the runner holding pin on the upper mold side, and only the molded part (primary object) of the molded object is held. When separated, only the molded part remains attached to the lower mold side, while the finished molded article in the finishing mold is opened with its entirety attached to the lower mold side. Subsequently, after the upper mold for primary molding is opened, the lower mold is inverted while remaining attached to the lower mold side, and the combination of the two sets of molds is changed, so that the primary molding is applied to the finishing molding side. Molded products are supplied.

In the above process, the apparatus of the present invention is mainly involved in the stage of opening the upper mold for primary molding.

That is, in the above molding cycle, the period from the reversal of the lower mold to the next mold opening is taken as a unit, and when the lower mold is reversed, the hook portion 54 of the hook-shaped engaging hand 52 on the lower mold side is connected to the upper mold for primary molding. The hook portion 58 of the hook-shaped engaging hand 56 and the fixed plate 38 are wrapped around to form an intersectable state. Next, after passing through a predetermined molding process, the mold opening process is started.

In the mold opening process, first the movable platen 2 to which the lower mold is fixed is
4 moves back and the upper mold and lower mold are opened. Subsequently, the movable platen further retreats and the hook portion 5 of the engaging hand
4 and 58 come into contact to form a cross-engaged state, and based on this, the retreating force of the movable platen is transmitted and the first sheet 12 of the upper die for primary molding is pulled out. When the first sheet 12 is pulled out guided by the guide pin 28 and comes into contact with the stopper 30 to stop the separation movement between the first sheet 12 and the second sheet 14, the two sheets are then pulled out through the guide pin 28. The retreating force of the movable platen is transmitted to eye 14,
The second sheet is drawn. The second sheet guided by the guide pin 32 and pulled out comes into contact with a stopper 34 at the tip of the guide pin 32 and stops. In this way, the mold opening of the upper mold for primary molding is completed, and this mold opening is for taking out the runner sprue portion of the primary molded body in the upper mold. That is, the first sheet 12 and the second sheet 14 are separated to form a space for taking out the runner sprue part, and when the upper mold is in a closed state, the runner holding pin 36 that protrudes slightly from the second sheet is attached. 2 to remove the runner sprue held at the tip from the pin 36.
The first sheet is drawn out. When the upper mold for primary molding is finished opening, the lower mold is turned over again, and the finished product is delivered from the lower mold, while the remaining part of the primary molded product is delivered from the upper mold for primary molding. The runner sprue part is taken out and the process moves on to the next mold clamping process. In this way, the same operation is repeated and the desired molded product is intermittently obtained.

Advantages of the invention According to the invention, since a cross-engagement method using hook-shaped engagement hands is used, the mold can be opened and closed smoothly even with low mold opening force or mold clamping force, and the mold can be opened and closed smoothly. No impact force is applied when engaging or disengaging. In addition, contact between the engaging hands is substantially made only during the mold opening process of the upper mold for primary molding, and the hooks do not rub against each other when crossing, reducing the burden on the molding machine and the mold. At the same time, the amount of wear and tear on the engaging hand is small, and this also helps to provide the mold opening device for the upper mold with excellent durability.
As a result, the frequency of replacement due to damage etc. is reduced, and production efficiency is improved accordingly. Incidentally, no abnormality was observed in the product of the above example even after repeating the cycle approximately 150,000 times (90 days in total, 24 hours of operation per day).

In addition, the hook-shaped engaging hand in the device of the present invention has a simple structure and is easy to manufacture, and the device of the present invention has the advantage of being easy to assemble, and there is almost no mold failure or damage. It also has the advantage of being reduced to a certain degree.

[Brief explanation of the drawing]

Fig. 1 is an explanatory plan view of a twin injection molding machine, Fig. 2 a and b are sectional views of a conventional mold opening device, Fig. 3 is an explanatory view of the mold opening state by the device of the present invention, Figs. FIG. 5 is a perspective view of the hook-like engaging hand in the device of the present invention. Main symbols in the drawings, 2, 4... Injection device, 10,
20... Upper die of the mold, 12... First piece of the upper die for primary molding, 18, 22... Lower die of the die, 24... Movable plate, 26... Mold rotating plate, 38... ...Fixed board, 5
2,56...Hook-shaped engagement hand.

Claims (1)

[Claims for Utility Model Registration] Consisting of two injection devices and two sets of molds, one for primary molding and one for finishing molding, the primary mold in the two sets of molds each consists of a pair of an upper mold and a lower mold. The upper mold for molding is a vertically split mold with a triple structure that can be opened.
In a twin-shot injection molding machine that enables two-color molding by repeatedly reversing the lower mold of the body and alternately changing the combination of two sets of molds, an engaged state is formed when the hooks intersect with each other. One of the hook-shaped engaging hands is placed on each side of the two lower molds, and the other is placed on the side of the first piece from the lower mold side of the upper mold for primary molding when the upper mold is opened. It is attached at a position where it can be engaged with the hook-shaped engagement hand of the mold 1
Mold opening device for the upper mold for the next molding.