JPH0233469B2 - - Google Patents

Description

Detailed Description of the Invention The present invention uses a mold gas venting device for extracting a large amount of gas from the cavity of a mold during injection of an injection molding device such as a die casting machine or an injection molding machine. This relates to an injection molding method in which hot air is blown into the cavity to sufficiently remove water droplets within the cavity before injection is performed.

Traditionally, in injection molding equipment such as die casting machines, cooling water or a water-soluble mold release agent was sprayed onto the mold after the mold was opened, but when the mold was clamped,
If water droplets remain in the mold, there is no place for the water droplets or steam to escape, and if the mold is injected as is, the surface of the injected product will become black, the hot water circulation will be poor, and cavities will form, making it difficult to obtain high-quality injected products. I couldn't do it. Therefore, in the past, it was necessary to clamp the mold after the water droplets on the surface of the mold had sufficiently dried and disappeared.

On the other hand, there has been no satisfactory device capable of sufficiently, reliably and easily discharging gas and water vapor within the cavity to the outside of the mold without discharging the molten metal to the outside of the mold.

This invention is intended to solve these problems.

For this purpose, in the present invention, a valve that is slidable in the axial direction is provided at the end of a gas vent groove led from the cavity on the separation surface of the mold, and a movement path of the valve is provided in the middle of the gas vent groove. a first gas exhaust path that communicates with the side surface of the mold, and a second gas exhaust path that communicates with the outside of the mold from the side surface of the valve movement path that is the end of the first gas exhaust path; and the first
A gas venting device for a mold, wherein the valve that opens the gas exhaust passage is directly moved by the inertial force of the molten material to be injected advancing from the cavity to directly shut off the first gas exhaust passage. After mold clamping, hot air was sent into the cavity through an open valve device, followed by injection.

Next, the present invention will be explained in more detail with reference to an embodiment shown in the drawings.

In one embodiment of the mold degassing device shown in FIGS. 1 to 3, 3 is a fixed mold, and 4 is a movable mold.

On the side of the movable mold 4, an extrusion plate is provided that is moved forward and backward by a cylinder (not shown), etc.
This is provided with a plurality of push-out pins 6.
A cavity 7 is formed in the abutting surfaces of the fixed and movable molds 3 and 4, and below the cavity 7 is a molten material that is injected by an injection cylinder (not shown). A metal casting hole is formed.

On the other hand, on the fixed mold 3 side or the movable mold 4 side, a gas venting path 9 having a sufficient area is provided around the cavity 7 in a portion facing the other mold 3. A gas vent groove 10 is provided in communication with the upper end of the gas vent. This gas vent groove 10 may be formed in a shared state on the dividing surface of the two molds 3 and 4.

The valve head faces the gas vent groove 10 led from the cavities 7 of the molds 3 and 4 and is moved directly in the direction of action of the molten metal by the action of the molten metal advancing from the cavities 7. A disk type valve 14 is provided.

18 is a cylinder attached to the fixed mold 3 via a bracket 40, 19 is a piston rod of the cylinder 18, and at the lower end of the piston rod 19 is a spool 22 consisting of several parts that can be assembled and disassembled.
is fixed, and the spool 22 is slidably provided in a vertical half hole 23 provided in the fixed mold 3 and a vertical half hole provided in the movable mold 4 that matches this half hole. . A chamber 24 is provided in the upper part of the spool 22, and a gas exhaust hole 13 opened downward is provided in the lower part of the spool 22.
A tapered valve seat 12 is provided. A rod 25, which is a vertical valve stem, is provided at the center of the upper end of the valve 14, and a nut-shaped head 26a is attached to the tip of the rod 25, which penetrates into the chamber 24. Of course, Rod 25
is provided slidably on the spool 22. room 2
A compression spring 17 was attached between the upper surface of the head 26a of the valve 14 and the ceiling surface of the spool 22 in the spool 22. However, a compression spring 17 may be provided around the rod 25 between the upper end surface of the valve head 14b of the valve 14 and the bottom surface of the gas discharge hole 13 of the spool 22. Furthermore, a cylinder stroke may be provided instead of the compression spring 17.

A gas exhaust path 20 leading to the outside of the mold was communicated with the gas exhaust hole 13. The outlet of this gas exhaust path 20 is made to be open to the outside air and to be communicated with a hot air blowing device (not shown).

Following the gas vent groove 10, a valve chamber 11 that can be split in half is provided on both dividing surfaces of the two molds 3 and 4.
As can be seen from FIGS. 1 and 2, the valve chamber 11 includes an upper large diameter portion 11a into which the spool 22 is inserted, and a valve 14.
The valve head installation hole 11b is a small diameter portion at the lower end into which the valve head 14b of the valve head 14b is inserted.

The valve head 14b of the valve 14 has a tapered surface on the outer periphery of the back surface that seats on the valve seat 12, and when the valve head 14b is at the lower limit, the valve head 14b is in the valve chamber 11 where the valve head is installed. The outer peripheral surface of the valve head 14b is slidably fitted into the inner peripheral surface of the lower end of the valve chamber 11. 14a is a dish-shaped recess provided on the lower surface of the valve head 14b.

From the middle of the gas vent groove 10 just before the valve chamber 11,
A bypass 15 is provided between the side surface of the valve chamber 11 in front of the valve seat 12, which is the side surface of the movement path of the valve head 14b, and the side surface of the valve chamber 11, which is the side surface of the movement path of the valve head 14b.
By operating the valve 14, communication and interruption of the gas exhaust path between the bypass 15 and the outside of the mold can be directly regulated. The intersecting angle θ between the gas vent groove 10 and the inlet of the bypass 15 was set to be an acute angle or a right angle. Valve chamber 1
The opening 16 of the gas venting groove 10 facing 2 is narrowed in the shape of a nozzle.

The spool 22 is slidably held by a guide 41 attached to a part of the bracket 40. Further, sensors 42 and 43 such as a limit switch and a non-contact switch are provided on the side surface of the bracket 40, and sensors 42 and 43 are provided on a part of the spool 22.
Attach the bar 44 that activates the sensor 4.
2 and 43 to confirm the lower limit and upper limit of the spool 22. From the head 26a of the valve 14, the bar 4
5 is provided by extending to the outside of the spool 22 through the notch 22a of the spool 22, and a sensor 46 such as a limit switch or a non-contact switch is attached to a part of the spool 22, and the bar 45 is connected to the sensor 46.
Valve 1 by making sure it is away from
4 is securely separated from the valve seat 12 and opened before pouring the molten metal. And valve 14
Once you have confirmed that the is open, you can begin pouring molten metal.

Injection using the gas venting device configured as described above is performed as follows.

First, in the mold open state, the cylinder 18 is operated and the spool 2 is inserted through the piston rod 19.
2 is raised, and the force of the compression spring 17 keeps the valve 14 open.

In this state, cooling water or a water-soluble mold release agent is sprayed onto the surface of the cavity 7 of the mold. in this case,
Water droplets form on the surface of the cavity 7. and,
Water droplets formed on the surface of cavity 7 evaporate to some extent and become water vapor due to the heat of the mold, but if the injection product is complex and the surface of cavity 7 is quite deep, all the water droplets on the surface of cavity 7 will evaporate. Instead of turning into water vapor, it remains as water droplets.

Therefore, in the present invention, hot air is sent into the cavity 7 after the mold is clamped to forcibly evaporate water droplets on the surface of the cavity 7, as will be described later.

When the spraying operation is completed, the mold is clamped with the valve device raised, that is, with the valve 14 floating above the lower end of the valve chamber 11, and the cylinder 18 is closed with the valve chamber 11 aligned. The lower end of the spool 22 is inserted into the valve chamber 11 to the lower limit position, and the valve head 14b is moved to the normal installation position of the valve head 14b, that is, at the back of the valve head installation hole 11b just above the mouth part 16. to ensure that the valve 14 is in close contact with the lower end of the valve chamber 11.

In addition, if foreign matter is present on the wall of the valve head installation hole 11b or around the mouth 16 of the gas vent groove 10,
When valve 14 is prevented from lowering, bar 4
5 and the sensor 46 are not activated, the valve head 14b is not inserted all the way, and the valve 14 is in a raised position relative to the spool 22. As a result, no signal indicating that the valve 14 is set to the normal position is generated, the injection cylinder is not operated, and no casting operation is being performed.
Therefore, defects such as poor degassing do not occur.

After the valve head 14b is securely set in the valve head installation hole 11b, hot air is sent from the gas exhaust path 20,
14 open valves of the degassing device, bypass 1
5. Sufficient hot air is sent into the cavity 7 of the mold through the gas vent groove 10 and the like. Then, the water droplets remaining on the surface of the cavity 7 completely evaporate into water vapor, and together with the water vapor generated by evaporation due to the heat of the mold, they escape through the injection sleeve by the action of hot air. Of course, not all of the water vapor escapes to the outside through the injection sleeve, and some of it may remain in the cavity 7 together with the gas. This feeding of hot air can also be performed after mold clamping or during hot water supply.
Therefore, if hot air is sent into the cavity through a gas venting device during mold clamping, the mold can be clamped quickly after spraying, and the cycle will be shortened.

After the hot air has been fed for a predetermined period of time, the hot air is stopped, the molten metal is injected into the injection sleeve, and the injection is performed.

Then, while filling the cavity 7 with molten metal, the gas and remaining water vapor in the cavity 7 can be removed from the gas vent path 9, the gas vent groove 10, the bypass 15,
The gas is discharged from the gas discharge passage 20 through the gas discharge hole 13 in the spool 22 . During this time, the valve 14
Since the valve head 14b is the lower end of the valve chamber 11, the mouth 16 of the gas vent groove 10 remains closed, and a large amount of gas and water vapor escape through the bypass 15.

Of course, at this time, the gas and steam pass through the mouth 16 and act on the lower surface of the valve head 14b, but since the mass of the gas and steam is extremely small, the valve 14 does not rise.

When the filling of the molten metal into the cavity 7 is almost completed, the molten metal with a large mass rises in the gas vent groove 10 and collides with the lower surface of the valve head 14b, and as a result, the valve 14 resists the compression spring 17. It is pushed up and hits the valve seat 12, closing it. Molten metal valve 1
4 is pushed up, a portion of the metal enters the bypass 15, but since the valve 14 is closed, the molten metal is blocked.

At this time, most of the gas and water vapor that escaped through the bypass 15 have escaped.
Only a small amount remains near the valve seat 12. This does not have any negative effect on the cast product.

In other words, in this mold degassing device, injection is performed with the gas exhaust path leading from the mold cavity to the outside of the mold opened by the action of a valve, and gas and water vapor with a small mass in the cavity are degassed. At the point when the discharge through the discharge passage is almost finished, the inertial force of the large mass of the molten material to be injected that has advanced from inside the cavity is applied directly to the valve,
moving and closing the valve securely and quickly;
The valve directly blocks the gas exhaust path and prevents the melt to be injected from flowing out from the gas exhaust path, so that the gas inside the mold can be reliably and easily vented during injection.

When the casting work is completed, the cylinder 18 is operated to raise the piston rod 19 and the spool 2
2 and valve 14 are raised to a certain extent, the mold is opened. Subsequently, by operating the extrusion pin 6, the cast product is taken out from the movable mold 4, and at the same time, the metal solidified in the gas vent groove 10, the valve chamber 11, and the bypass 15 is taken out.

In this way, in this invention, since the structure as described in the claims is adopted, water droplets generated on the cavity surface of the mold by spraying can be sufficiently removed by hot air. The gas and steam in the cavity are sufficiently discharged through the gas venting device as the molten metal advances during injection, and the valve of the gas venting device can be automatically, instantaneously, reliably and easily closed by the action of the inertia of the molten metal. Therefore, it is possible to easily obtain a high quality injection product with no cavities and a clean surface. Of course,
Inconveniences such as spouting of molten metal do not occur.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of an apparatus for carrying out the method of the present invention, and FIG.
3 is a sectional view taken along the - line in FIG. 2. 3... Fixed mold, 4... Movable mold, 7... Cavity, 10... Gas vent groove, 11... Valve chamber, 1
1b...Valve head installation hole, 14...Valve, 14b...Valve head, 15...Bypass, 18...Cylinder, 20
...Gas exhaust path, 22...Spool, 46...Sensor.

Claims (1)

[Claims] 1. A valve that is slidable in the axial direction is provided at the end of a gas vent groove led from the cavity on the separation surface of the mold, and a first valve that communicates from the middle of the gas vent groove to the side surface of the movement path of the valve is provided. providing a gas exhaust path, and providing a second gas exhaust path that communicates with the outside of the mold from a side surface of the movement path of the valve, which is an end of the first gas exhaust path,
and the valve that opens the first gas exhaust passage can be directly moved by the inertial force of the molten material to be injected advancing from the cavity to directly shut off the first gas exhaust passage. An injection molding method using a mold gas venting device, in which hot air is sent into the cavity through an open valve device after the mold is clamped, and injection is then performed.