JPH0727140Y2 - Thread pull prevention device for injection mold - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread-pulling prevention device for an injection-molding die, which prevents threading of the injection-molding die during injection molding of a thermoplastic resin.

[0002]

2. Description of the Related Art Conventionally, in a thermoplastic resin injection molding operation, after a molten resin is injected into a mold cavity, when the molten resin in the cavity solidifies, the mold is opened and a molded product is taken out. At this time, the cooling and solidification of the molten resin injected into the cavity is sequentially progressed inward from the portion in contact with the mold. At this time, the molten resin injected from the sprue into the runner portion is similarly solidified.

However, since the resin on the injection nozzle side of the injection molding machine is always in a molten state during operation, if the mold is opened after the required time has elapsed, the sprue part of the sprue is released from the mold. The molten resin in the vicinity of the shaft center is stretched at the contact portion with the nozzle, and a stringing phenomenon occurs.

[0004] Thus, when the molten resin is stringed when the mold is opened, the mold parting line is damaged, automatic operation is hindered due to continuous falling trouble of the molded product, and the runner and the molded product are entangled by the yarns entangled with each other. However, there are various problems such that it takes a long time to sort, the yarn remains in the mold cavity, and burrs and sink marks are generated in the next molded product, resulting in a defective product.

By the way, in order to eliminate the stringing, a stringing prevention cap 20 as shown in FIGS. 9 and 10, for example, is used. This string pull prevention cap 20
Is a spherical shape that follows the contact surface of the sprue bush 21 of the mold with the nozzle 22, and a thin baffle plate 24 that is inserted into the sprue 23 and blocks the axial center is attached to the central portion. The stringing prevention cap 20 is fixed to the joining surface of the nozzle 22 of the sprue bush 21 with an adhesive tape 25,
By the baffle plate 24, the resin near the axial center of the sprue 23, which causes the stringing, is dropped to try to eliminate the stringing.

[0006]

[Problems to be Solved by the Invention] However, since the sprue 23 portion of the mold is tapered to spread to the runner side in order to smoothly release the molded product, When used, the small gap 27 formed by the inclined surface 26 of the sprue 23 and the side surface 24a of the baffle 24 is also filled with the resin. The resin solidified in this small gap 27 is
There is a problem that when the mold is opened, it remains in the sprue 23 and prevents the sprue 23 part from being discharged together with the molded product, which impedes continuous operation. Also, the thread pull cap 20
Since is attached to the sprue bush 21 with the adhesive tape 25, there is a problem that it is dropped and lost when the mold is replaced.

In order to solve such a problem, the present invention does not hinder continuous operation due to the formation of a small gap between the inclined surface of the mold sprue and the side surface of the baffle plate. Another object of the present invention is to provide a yarn pulling prevention device for an injection molding die, which does not fall off and lose when the die is replaced.

[0008]

In order to achieve the above-mentioned object, a device for preventing thread pulling of an injection molding die according to the present invention is provided on a nozzle side of a molding machine in a sprue bush of the injection molding die. It is characterized in that a groove crossing the sprue axis is provided via a flow path of the molten resin, and a baffle plate crossing the sprue axis is fitted and provided in the groove. Alternatively, on the nozzle side of the molding machine in the sprue bush of the injection molding die, there is provided a recess into which a block having a flow hole for the molten resin is fitted, and the flow path hole for the molten resin in this block is provided with the axial center thereof. A baffle that traverses the sprue axis is provided so as to penetrate in the direction.

The molten resin injected from the tip of the nozzle of the injection molding machine is temporarily split by the baffle plate, passes through the sprue and runner, and is filled in the cavity. The baffle plate causes the resin to have a shape in which the axial center portion is missing near the sprue nozzle, and the mold opening is performed in a state where it is completely solidified near the sprue nozzle, and stringing does not occur. .

In addition, the baffle plate is provided by inserting the baffle plate into the groove that traverses the sprue axis through the flow path of the molten resin so as to traverse the sprue axis, or to fit into the recess provided in the sprue bush. By providing the block having the flow path hole of the molten resin provided across the sprue axis so as to penetrate the flow path hole in the axial direction thereof, the inclined surface of the sprue and the side surface of the baffle plate Since no small gap is created, there is no obstacle to continuous operation due to resin pieces remaining in the mold. In addition, it will not fall off and be lost when the mold is replaced. Furthermore, in the latter,
If the baffle is damaged, it can be replaced with a new one and used reliably.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the yarn pulling prevention apparatus for an injection molding die according to the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of an injection molding die 1 according to the present invention.
Equipped with 2. This injection mold 1 has guide pins
The fixed side base 4 along with the nozzle 8 side, the attached plate 5 of this fixed side base 4, the cavity plate 6, and the core plate 7 are combined in this order, and the part where the nozzle 8 contacts to form the sprue 9 is the sprue. As the bush 10, the fixed-side base 4 is fitted into the fixed-side base 4 and the attached plate 5 of the fixed-side base 4, and is attached to the fixed-side base 4 by the locate ring 11.

During molding, the molten resin is injected into the nozzle of the molding machine.
8 It is injected from the tip into the injection mold 1 and sprue 9,
The cavity 13 is filled by passing through the runner 12.

As shown in FIGS. 2 and 3, the contact surface 10a of the sprue bush 10 with the nozzle 8 is engraved with a groove 14 that traverses the axis of the sprue 9.
A thin baffle plate 15 is inserted into the sprue 9 so as to cross the axis of the sprue 9.

As described above, since the baffle plate 15 is fitted in the sprue bush 10, the molten resin injected from the tip of the nozzle 8 is once diverted by the baffle plate 15 and passes through the sprue 9 and the runner 12. To fill the cavity 13. This baffle plate 15 allows the resin to sprue 9 nozzles 8
Since the central part is omitted in the vicinity, the axial center part of the sprue 9 in the vicinity of the nozzle 8 is completely solidified and the mold opening is performed, so that the stringing does not occur.

Further, unlike the conventional stringing prevention cap 20 shown in FIGS. 9 and 10, a small gap is not formed by the inclined surface 26 of the sprue 9 and the side surface 24a of the baffle plate 24, The resin pieces do not remain in the mold and hinder continuous operation.

In the above embodiment, one baffle plate 15 is fitted in the groove 14 at a required position of the sprue bush 10 and the construction is described. However, as shown in FIGS. Groove 14 and groove 14 'with a step and cross,
Baffle plates 15 and 15a with a height corresponding to the depth of each groove 14 and 14 '
Can be provided so as to traverse the axis of the sprue 9 and have the exposed end surface contacting the tip surface of the nozzle 8.
In this way, the flow path is reduced in the sprue 9 portion, but the axial center is surely blocked, and the stringing is prevented.

Further, as another embodiment, FIG. 6 and FIG.
As shown by, the flow path hole of the molten resin, its axial direction,
In other words, the block 15A, in which the baffle plate 15b that crosses the sprue axis is formed in advance so as to penetrate in the direction orthogonal to the axis of the flow path hole, is fitted into the recess 10C provided on the end surface of the sprue bush 10. It is possible to adopt a configuration in which it is made to. In the case of the sprue bushing 10 configured in this way, if the baffle plate 15b is damaged, it can be replaced with a new one and used reliably. Even when the block 15A is provided with the baffle plate 15b, it is possible to adopt a structure in which the baffle plate 15b is crossed as shown in FIG. And with such molded body (block), the baffle plate
It is also possible to divide 15b into three equal parts.

[Brief description of drawings]

FIG. 1 is an overall vertical cross-sectional view of an embodiment equipped with a thread pull prevention device for an injection molding die according to the present invention.

FIG. 2 is a front view of a yarn pulling prevention device for the injection molding die in FIG.

FIG. 3 is a vertical cross-sectional view of FIG.

FIG. 4 is a front view of another embodiment of the yarn pulling prevention device for an injection molding die according to the present invention.

5 is a vertical cross-sectional view of FIG.

FIG. 6 is a front view of still another embodiment of the yarn pulling prevention device for an injection molding die according to the present invention.

7 is a vertical cross-sectional view of FIG.

FIG. 8 is a front view showing another application example of the stringing prevention device of the injection molding machine according to the present invention.

FIG. 9 is a front view of a conventional stringing prevention cap.

FIG. 10 is a vertical cross-sectional view of an injection molding die in which the stringing prevention cap of FIG. 9 is attached.

[Explanation of symbols]

 1 Injection Molding Mold 2 Injection Molding Thread Pull Prevention Device 3 Guide Pin 4 Fixed Side Base 6 Cavity Plate 7 Core Plate 8,22 Nozzle 9,23 Sprue 10,21 Sprue Bushing 10a Contact Surface 10C Recess 12 Runner 13 Cavity 14, 14 'Grooves into which baffle plates are fitted 15, 15a, 15b Baffle plates 15A blocks 20 Thread pull prevention caps 24 Baffle plates 24a Side surfaces 25 Adhesive tapes 26 Sloping surfaces 27 Small gaps

Claims (2)

[Scope of utility model registration request] 1. A sprue bush of an injection-molding die is provided with a groove crossing the sprue axis on a nozzle side of a molding machine through a flow path of molten resin, and the groove crosses over the sprue axis. A string pulling prevention device for an injection molding die, characterized in that a plate is fitted and provided. 2. A sprue bush of an injection molding die is provided on the nozzle side of a molding machine with a recess into which a block having a flow hole for molten resin is fitted, and the flow path hole for molten resin in the block is formed. A stringing prevention device for an injection molding die, which is provided with a baffle plate that traverses the sprue shaft center so as to penetrate in the axial direction.