JP2002225096A - Vacuumizing mold structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuumizing mold structure rich in durability, removing such a defect that a conventional vacuumizing mold structure has no durability and it is difficult to bring a cavity to a high vacuum degree for a short time and performing molding in such a state that the cavity is brought to a high vacuum degree to obtain a molded product having a highly accurate dimension and excellent in surface transfer properties. SOLUTION: The vacuumizing mold structure has the fixed mold attached to a fixed platen, the movable mold attached to a movable platen, an ejection pin for taking out the molded product from the cavity for molding the molded product by a pair of the molds, an ejection plate connecting the ejection pin to move the same and a space part for storing the ejection pin and the ejection plate and further has a vacuum opening part for evacuating the cavity and the space part immediately before molding and the seal structure provided to the movable platen in order to seal the cavity and the space part under vacuum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum mold for use in a die casting machine, an injection molding machine or the like.

[0002]

2. Description of the Related Art A conventional vacuum evacuation mold of this type will be described with reference to FIG. 2 using an example of die casting.
After the movable mold 4 attached to the movable platen 3 is joined at the joint surface A and the cavity 5 is formed by joining the fixed mold 2 and the movable mold 4, the molten molding material is injected into the cavity 5. Molding. Immediately before the molding, the cavity 5 is evacuated from a vent 23, which is an opening for evacuation, provided on the joint surface A by a vacuum device (not shown) so as to make the cavity 5 in a vacuum state.
, Mainly air, is discharged to reduce the pressure inside the cavity 5 to make it a vacuum state. After the molding is completed, the movable mold 4 is separated from the fixed mold 2 at the joint surface A, but the molded product is left in the space where the cavity 5 of the movable mold 4 was formed. Therefore, in order to remove the molded product from the movable mold 4, the extrusion pin 6 and the extrusion plate 7 are incorporated into the movable mold 4, and the extrusion pin 6 is moved by a predetermined distance to the left in the figure to remove the molded product. It is structured to be pushed out from the movable mold 4. The extruded product is transported to a predetermined place by an industrial robot (not shown) or the like and stored in advance. However, when molding is performed, if air at atmospheric pressure remains in the cavity 5, the air may be mixed into the molded product, or air may enter the boundary surface between the cavity 5 and the molded product. A nest may appear on the molded product, resulting in poor dimensional accuracy, or the surface of the cavity 5 may not be sufficiently transferred to the surface of the molded product. Therefore, in order to produce a high quality molded product, the cavity 5 must be evacuated and molded immediately before molding. For this purpose, the cavity 5 needs to be provided with a vacuum seal structure for preventing the inflow of air from the outside. The extrusion pin 6 and an O-ring 8 for vacuum seal are provided in a hole passing therethrough. An O-ring 9 for vacuum sealing is also provided on the joining surface A, and the cavity 5 is
In step 3, a vacuum is drawn by a vacuum device (not shown).

[0003]

However, the O-ring 8 in the push-out pin 6 generates frictional heat and wear of the O-ring 8 itself when the push-out pin 6 moves. The material of the O-ring 8 is thermally degraded at a high temperature or the like at which the O-ring 8 is propagated, and the O-ring 8 loses its elasticity, so that the sealing effect cannot be sufficiently exhibited. Therefore, it has been difficult to bring the cavity 5 into a high vacuum state in a short time immediately before molding for a long time.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional vacuum evacuation mold structure that it is difficult to achieve a high degree of vacuum in the cavity in a short period of time without durability. An object of the present invention is to provide a mold structure for vacuum evacuation, which is molded to a degree of vacuum and has high durability and obtains a molded product having high accuracy and excellent surface transferability.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a fixed die mounted on a fixed platen, a movable die mounted on a movable platen, and a molded product formed by the pair of dies. In an evacuation mold having an extrusion pin for taking out a molded product from a cavity for molding an extrusion pin, an extrusion plate for connecting and moving the extrusion pin, and a space for storing the extrusion pin and the extrusion plate, the cavity is formed immediately before molding. And a vacuum opening for reducing the pressure in the space, and a seal structure provided on the movable plate for vacuum-sealing the cavity and the space.

Further, a vacuum cooling mold is further characterized by flowing a cooling medium near a sealing material of a vacuum seal structure provided on a joint surface between a fixed mold and a movable mold in order to vacuum seal the cavity. It is preferable to have a structure.

Further, it is more preferable that the vacuum opening has a vacuum evacuation mold structure for simultaneously performing evacuation.

As a result, the degree of vacuum in the cavity can be kept high, the sealing material for vacuum sealing is not affected by heat deterioration, and the life of the sealing material is long and the sealing effect is exhibited.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1 in the case of die casting. A vacuum evacuation mold 10 comprises a fixed mold 12 attached to a fixed plate 11 and a movable plate 13. And a movable mold 14 attached thereto. The opening and closing method of the evacuation mold 10 is as follows.
It is not movable because it is attached to
4 is attached to the movable platen 13 and moves together with the movable platen 13.
Since the movable platen 13 is connected to a mold opening / closing unit of a die casting machine (not shown), it is determined by the movement of the mold opening / closing unit. The joint surface between the fixed mold 12 and the movable mold 14 is B, and B
Are mutually opened and closed on the surface. Fixed mold 12 and movable mold 14
Is bonded to the cavity B, which is a female mold space with respect to the outer shape of the molded product to be molded, by injecting the molding material in a molten state at a high temperature into the cavity 15 to form the molded product. By accurately transferring and shaping the shape of No. 15, a molded product with good dimensional accuracy can be obtained. In particular, the accuracy of the transfer of the external dimensions of the cavity 15 and the surface thereof determines the quality of the molded product. However, if a gas such as air exists in the space of the cavity 15, the gas mixes with the molding material in a molten state during injection molding. As a result, gas is mixed into the molded product, resulting in a molded product having bubbles and nests, which is a defective product. In addition, in high-speed injection molding, the gas undergoes adiabatic compression to a high temperature, and the raw material in a molten state that cannot withstand the high temperature itself undergoes thermal deterioration and discolors or burns. In some cases, a defective molded product is produced. To prevent such a problem, the gas in the cavity 15 is removed immediately before the molding, and then the molding is performed by injecting a molten molding material. The purpose is to create a vacuum evacuation mold 10
It is. Therefore, immediately after molding, the cavity 15 is brought into a high vacuum state and then molded, so that the transferability of the cavity surface to the molded article is improved, the dimensional accuracy is improved, and the molding is excellent in quality without bubbles and cavities. Goods are obtained. Therefore, in order to bring the cavity 15 into a high vacuum state, the gas in the cavity 15 must be exhausted from the vent 23 and the vacuum opening 24 by a vacuum device (not shown).
On the other hand, it is necessary to prevent the air in the atmosphere from flowing into the cavity 15. For that purpose, it is necessary to provide a vacuum sealing structure at a place where air flows. In this embodiment, a vacuum seal structure is provided on the joint surface B. The vacuum seal structure is made of a plastic O
Place the ring 25 and shut off the air. As the material of the O-ring 25, a material made of a fluorine-based plastic material which can withstand particularly high temperatures among plastics is used. The material of the ring 25 itself undergoes thermosetting, whereby the elasticity of the O-ring 25 itself is reduced and the sealing function is lost. Therefore, in order to prevent thermal deterioration of the material due to the high temperature of the O-ring 25, the cooling medium 17 flows near the O-ring 25 to prevent the temperature from becoming high.

After the injection molding is completed, to remove the molded product, the movable mold 14 is moved rightward in FIG. 1 to open the mold from the surface B. At this time, the cavity 15 of the movable mold 14 is opened. It is designed in advance so that the molded product is left in the formed space. Therefore, the molded product remains in the movable mold 14 when the movable mold 14 is moved to a predetermined position because the movable mold 14 is opened. As a method of removing the molded product remaining in the movable mold 14, the extrusion pin 16 is pressed against the molded product and protruded. The mechanism for removing the molded product from the movable mold 14 pushes the molded product through a hole formed in the movable mold 14 by an extrusion pin 16. The push-out pin 16 is fixed by a push-out plate 19, the push-out plate 19 is connected to a tip of a rod 20, and the other end of the rod 20 is provided with a blade 21,
The blade 21 can be moved to the left in the figure by a pushing mechanism (not shown). The space 18 required for moving the extrusion plate 19 and the extrusion pin 16 in the movable mold 14 needs to maintain the same degree of vacuum as the cavity 15 immediately before molding. Therefore, a vacuum sealing structure is necessary so that air does not enter from the outside, and an O-ring 26 for vacuum sealing is placed in the O-ring groove on the joint surface between the movable mold 14 and the movable platen 13. In this case, since the installation place of the O-ring 26 is far from the cavity, the temperature does not increase near the O-ring 26, and therefore, it is not necessary to flow the cooling medium. Further, the rod 20 is
Since the hole moves in the left and right directions in the figure, there is a gap between the hole and the rod 20, and a vacuum seal structure is necessary so that air in the atmosphere does not flow into the space 18 through the gap. For this purpose, an O-ring 27 is placed in the O-ring groove near the exit or entrance of the hole. This setting location is also located sufficiently away from the cavity 15, the temperature does not increase near the O-ring 27, and there is no need to flow a cooling medium.

In order to make the cavity 15 in a vacuum state, the mold 10 is evacuated from the vent portion 23 on the joining surface B. In addition, the vacuum opening 2 in the space 18 is additionally provided.
At the same time, vacuum evacuation is performed from step 4. The reason is that a part of the gas in the cavity 15 is guided to the space 18 through the gap between the extrusion pin 16 and the hole, passes through the vacuum opening 24,
Since it passes through the vacuum pipe 22 and is guided to a vacuum device (not shown) and plays a role of bringing the cavity 15 into a vacuum state, it is possible to reach a high degree of vacuum in a short time.

With the structure as described above, the O-ring for sealing between the atmospheric pressure and the inside of the cavity has no thermal deterioration and has a long life, so that the cavity can be maintained in a high vacuum in a short time. It has become possible.

[0013]

As described above, in the present invention,
Removed the drawback that conventional evacuating molds had difficulty in increasing the vacuum to a high degree of vacuum in a short period of time without durability and molded the cavity to a high degree of vacuum. A mold structure for vacuum evacuation with high durability to obtain a molded product having excellent surface transfer properties was obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a vacuum evacuation mold structure for a die casting machine, showing one embodiment of the present invention.

FIG. 2 is an explanatory view of a conventional evacuation mold structure for a die casting machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Die 11 Fixed plate 12 Fixed die 13 Movable plate 14 Movable die 15 Cavity 16 Extrusion pin 17 Cooling groove 18 Space part 19 Extruded plate 20 Rod 21 Plate 22 Vacuum piping 23 Vent part 24 Vacuum opening 25, 26, 27 O-ring

Claims (3)

[Claims] 1. A fixed die attached to a fixed platen, a movable die attached to a movable platen, an extrusion pin for taking out a molded product from a cavity for molding the molded product with the pair of dies, and an extrusion. In an evacuation mold having an extruding plate for connecting and moving pins and a space for storing the extruding pin and the extruding plate, a vacuum opening for reducing the pressure of the cavity and the space immediately before molding, and a cavity And a sealing structure provided on a movable plate for vacuum-sealing the space. 2. A cooling medium further flows near a sealing material of a vacuum seal structure provided on a joint surface between a fixed mold and a movable mold to vacuum-seal the cavity. Vacuum evacuation mold structure. 3. A vacuum evacuation mold structure according to claim 1, wherein said evacuation opening simultaneously performs evacuation.