JPH0263663A - Vacuum die casting device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the degree of vacuum in a cavity at the time of a high-speed injection by actuating a valve disk by an actuator to close a valve seat just before the shift to the high-speed injection and closing and holding the valve seat by the valve disk at the time of the high speed injection. CONSTITUTION:The actuator 35 is actuated to move the valve disk 32 upward and to close the valve seat 30A just before the shift to the high-speed injection by a cylinder tip 5. The valve seat 30A is immediately closed and held by the valve disk 32 when the high-speed injection is started as the plunger tip 5 moves further leftward in a cylinder sleeve 3. The gas of a parting material, etc., generated in the cavity is discharged via an evacuating vent 32 from an auxiliary evacuating vent 38 constituted of a bypass line 38A, an auxiliary passage 39, and a cross passage 30B.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a vacuum die casting device that performs die casting under a relatively high vacuum inside a cavity, and is capable of producing large quantities of precision castings of aluminum alloy. do,
For example, it is often used in the production of component parts for automobiles, motorcycles, etc.

[Conventional technology]

2. Description of the Related Art A vacuum die casting device conventionally used for boat fishing will be explained with reference to FIGS. 1 and 2.

First, a first conventional example will be explained with reference to FIG.

A cavity 1 is composed of a fixed mold 2A and a movable mold 2B. Reference numeral 3 denotes a cylindrical injection cylinder sleeve, one end (left side in the figure) is connected to the cavity I via a runner 7, and a pouring hole 4 is bored near the outer periphery of the other end.

Further, a plunger tip 5 is slidably disposed within the injection cylinder sleeve 3, and the plunger tip 5 is integrally connected to an injection cylinder (not shown) by a piston 6.

7 is a spool that can freely enter and exit the movable mold 2B and the fixed mold 2A, and this spool 7 is operated by an air cylinder, a hydraulic cylinder, etc.
When the movable mold 2B and the fixed mold 2A are closed, the lower end of the spool 7 is inserted into both molds, and when both molds are open, it is withdrawn from the outside of both molds. . The above-mentioned operation of the spool 7 can be easily achieved by sensing the position of the movable mold 2B using, for example, a limit switch, and controlling the pressure inside the air or hydraulic cylinder based on this output signal.

Further, a vacuum vent 8 is provided in the spool 7, with one end connected to the vacuum source P and the other end opening to a valve seat 7A provided at the lower end of the spool 7 on the side of the molds 2A and 2B. Therefore, when the spool 7 enters the molds 2A, 2B, the valve seat 7A is disposed within the molds 2A, 2B.

Reference numeral 9 denotes a gas venting groove that communicates the cavity 1 with the opening of the valve seat 7A toward the mold side, and a valve body 10 that can open and close the valve seat 7A of the spool 7 is disposed within this gas venting groove 9. When the valve body 1O is normally engaged (the upward pressing force on the valve body 10 is below a certain value), it holds the valve seat 7A open as shown in the figure. This is because it is pressed downward in the figure by a spring or the like (not shown).

Therefore, the lower end +OA of the valve body 10 on the side of the cavity I opens at a substantially right angle to the gas vent groove 9.

Reference numeral 11 denotes a bypass path that bypasses the side of the gas vent groove 9 and connects the lower side of the gas vent groove 9 and the nearby gas vent groove 9 including the JR seat 7A, when the valve body 10 is at least in the open state of the valve seat 7A. It is.

Next, a second conventional example is shown in FIG.

Note that the same reference numerals are used for structures that are the same as those in the first conventional example, and explanations thereof will be omitted.

20 is a valve body that opens and closes the valve seat 7A of the spool 7,
It is placed in the valve body storage chamber 21 bored in the molds 2A and 2B, and when it is placed in the valve body storage chamber 21 and holds the valve seat 7A open, the plunger tip is 5, just before the end of low-speed injection, and just before the start of high-speed injection, the valve body 20 escapes from the valve body storage chamber 21 and closes the valve seat 7A, and thereafter keeps the valve seat 7A closed until the end of the high-speed injection.

For example, the plunger tip 5 moves in the injection cylinder sleeve 3 and the position of the plunger tip 5 immediately before the transition from low-speed injection to high-speed injection is detected using, for example, a limit switch, and this output signal is used to control the air cylinder, hydraulic pressure, The valve body 20 is operated by driving an actuator (not shown) such as a cylinder.

Further, 22 is a bypass passage whose one end opens in the gas vent groove 23 connected to the cavity I, and whose other end opens in the vicinity of the valve seat 7A, bypassing the side of the valve body storage chamber 21.

Therefore, the gas vent groove 23 does not directly open into the valve body storage chamber, and thereby the pressure within the gas vent groove 23 does not directly act on the lower end portion 2OA of the valve body 20.

Next, the operation of the conventional example will be explained.

According to the first conventional example, the molten metal flows into the injection cylinder sleeve 3 when the plunger tip 5 opens the pouring hole 4 . Next, when the plunger tip 5 moves to the left in the figure and enters low-speed injection, the injection cylinder sleeve 3 is gradually filled with molten metal, and at the end of the low-speed injection, up to 7 parts of the hollow runner are filled with the molten metal.

In addition, during such low-speed injection, the inside of the cavity 1 is filled with gas vent grooves 9. Bypass path 11. Valve seat 7A, vacuum vent 8. The pressure is reduced by the vacuum pressure of the vacuum source P via.

Next, when the plunger tip 5 moves further to the left from the low-speed injection position and enters high-speed injection, the molten metal is ejected all at once into the cavity 1. At this time, the gas stored in the cavity 1 flows through the bypass path 11. , is discharged from the vacuum vent 8 via the valve seat 7A.

On the other hand, the molten metal filling the cavity 1 forms a jet and collides with the lower end 10A of the valve body 10 through the gas vent groove 9, and the valve body 10 receives an upward force due to the collision of this molten metal. It moves upward to close the valve seat 7A and cut off communication between the cavity 1 and the vacuum vent 8.

Next, to explain the operation of the second conventional example, similar to the conventional example in Section 1, after the molten metal flows into the injection cylinder 3, low-speed injection is started by leftward movement of the plunger tip 5, and when the low-speed injection ends, At this point, up to runner 7 is filled with molten metal. At this time, inside the cavity 1, the gas vent groove 23
．． Bypass path 22. valve seat? A. The vacuum vent 8 is connected to the vacuum source P, so the pressure is reduced.

Immediately before the transition to high-speed injection (immediately before the end of low-speed injection), a limit switch (not shown) detects the position of the plunger tip 5 just before transition to high-speed injection, and based on this output signal, the air cylinder (not shown) , an actuator such as a hydraulic cylinder is operated, and the driving force of the actuator moves the valve body 20 upward to close the valve seat 7A. Therefore, during high-speed injection, the gas vent groove 23. Bypass path 22 and vacuum vent 8 are cut off.

[Problem to be solved by the invention]

Such conventional vacuum die casting equipment has the following disadvantages.

First, in the first conventional example, the valve body 10 is operated by the molten metal that fills the cavity 1 during high-speed injection and collides with the lower end 10A of the valve body 10 through the waste removal groove 9, and receives the collision force. The body 10 closes the valve seat 7A, and while the valve body 10 closes the valve seat 7A, the molten metal and the # type agent, which are small in mass and are atomized, pass through the valve seat 7A together with gas from the vacuum vent 8. be discharged.

According to this, the atomized molten metal, mold release agent, etc. tend to adhere to the valve seat 7A, impairing the closing performance of the valve body 10, or clogging the vacuum vent, resulting in extremely poor maintainability.

Further, the valve body 10 momentarily applies a large impact force to the valve seat 7.
A, the deposits on the valve seat 7A are pressed against the valve body 10, and the opening performance of the valve body 10 is deteriorated.

Further, according to the second conventional example, during high-speed injection, the valve body 20 closes the valve seat 7A by the actuator, so that the gasified mold release agent in the cavity I is difficult to be discharged; is mixed into the product, causing bubbles or discoloration of the surface, which is undesirable.

Furthermore, during high-speed injection, the atmosphere enters into the cavity 1 from the mating surfaces of the molds, etc., and this causes the vacuum level inside the cavity 1, which was reduced during low-speed injection, to deteriorate (approaching atmospheric pressure). ) It is not possible to take advantage of the advantages of vacuum casting.

[Means to solve problems]

The vacuum die-casting device of the present invention was developed in view of the above-mentioned problems, and its main purpose is to provide a vacuum die-casting device with less deterioration of the degree of vacuum in the cavity during the injection process and good gas release. , In order to achieve the above purpose, the following steps were taken.

In other words, in a vacuum die casting machine that maintains a vacuum inside the cavity and injects the molten metal inside the injection cylinder sleeve into the cavity using a plunger tip, a spool and a varnish spool that are arranged to move forward and backward within the mold are drilled. a vacuum vent, one end of which is connected to a vacuum source, and the other end of which opens into a valve seat provided at the end of the spool entering the mold; A valve body that is operated by an actuator to open and close the valve seat; A bypass path that bypasses the valve body storage chamber and opens at one end into a gas vent groove that opens into the cavity, and the other end opens near the valve seat. a sub-vacuum vent that communicates with the vacuum vent by bypassing the bypass passage and the valve seat; In addition to creating a curved path, the actuator operates the valve body to close the valve seat just before the cylinder tip transitions from low-speed injection to high-speed injection, and the valve body keeps the valve seat closed during high-speed injection. It is something.

[Effect]

During low-speed injection with the plunger tip, the vacuum vent is in communication with the bypass path because the valve seat is held open, and the sub-vacuum vent is in communication with the bypass path, so the gas vent is This ensures that the inside of the cavity is evacuated.

On the other hand, just before the plunger tip shifts to high-speed injection, a position detection device such as a limit switch senses the position of the plunger tip, and the valve body closes the valve seat via an actuator.

According to this, the gas in the cavity does not adhere to the valve seat during high-speed injection, and since the bypass passage is in communication with the sub-vacuum vent during high-speed injection, the gas in the cavity is transferred to the sub-vacuum vent. At the same time, the vacuum can still be drawn into the cavity via the bypass path from the vacuum vent, and the degree of vacuum in the cavity will not deteriorate.

〔Example〕

Hereinafter, one embodiment of the vacuum die-casting apparatus according to the present invention will be described with reference to FIG.

Note that the same reference numerals are used for parts having the same structure as the conventional one, and the description thereof will be omitted.

Reference numeral 30 denotes a spool that can freely enter and exit the fixed mold 2A, and this spool 30 is operated by an air cylinder, hydraulic cylinder, etc. (not shown), and is connected to the movable mold 2B and the fixed mold. When the mold 2A is closed, the lower end of the spool 30 is inserted into the fixed mold 2A, and when both molds are open, it is removed to the outside of the fixed mold 2A.

The above-mentioned operation of the spool 30 can be easily achieved by sensing the position of the movable mold 2 using, for example, a limit switch, and controlling the pressure in the air or hydraulic cylinder based on this output signal.

Further, a vacuum vent 31 is provided in the spool 30, one end of which is connected to the vacuum source P, and the other end of which opens to a valve seat 30A provided at the lower end of the spool 30 on the fixed mold 2A side.

Therefore, when the spool 30 enters the fixed mold 2A, the valve seat 30A is disposed within the fixed mold 2A.

Reference numeral 32 denotes a valve body that opens and closes the valve seat 30A of the spool 30, and is disposed within the valve body storage chamber 33 bored in the fixed mold 2A. The period during which the valve seat 30A is held open is until just before the end of low-speed injection by the plunger tip 5'.In other words, just before the start of high-speed injection, the valve body 32 escapes from the valve body storage chamber 33. The valve seat 30A is closed, and the valve seat 30A is kept closed until the end of high-speed injection.

This is done by detecting the position of the plunger tip 5 just before the transition to high speed injection (immediately before the end of low speed injection) as the plunger tip 5 moves in the injection cylinder sleeve 3, using, for example, the limit switch 34, and using this output signal. The valve body 32 is operated by driving an actuator 35 such as an air cylinder or a hydraulic cylinder.

Reference numeral 36 denotes a bypass passage which has one end opening in a gas vent groove 37 connected to the cavity 1, bypasses the side of the valve body storage chamber 33, and has the other end opening in the vicinity of the valve seat 30A including the valve seat 30A. Therefore, the gas vent groove 37 does not directly open into the valve body storage chamber, and thereby the pressure within the gas vent groove 37 does not directly act on the lower end portion 32A of the valve body 32.

38 connects the vacuum vent 31 and the bypass passage 36 to the valve seat 3.
This is a sub-vacuum vent that communicates without going through 0A, and is configured as follows.

That is, 38A is a curved path (massive bent) formed in a plurality of bends on the mold matching surface of the fixed mold 2A and the movable mold 2B, and the gap between the curved path 38A is minute (for example, 0.1 ~0.3m+*), and its width is about 5 to 30 mm.

More specifically, the fixed mold 2A is provided with a mountain-shaped continuous protrusion 2C, the movable mold 2B is provided with a valley-shaped continuous recess 2D, and the gap between the continuous protrusion 2C and the continuous recess 20 forms a tortuous path. 3
8A is formed.

Further, a horizontal passage 30B that opens to the vacuum vent 31 is bored on the outer periphery of the spool 30.
In the state shown in FIG. 3 where 0 has entered the fixed mold 2A,
An auxiliary passage 38 communicating with the lateral passage 30B of the spool 30 is bored laterally from the mold matching surface of the fixed mold 2A.

Therefore, the vacuum vent 38 is connected to the tortuous path 38A, the auxiliary path 38. It is composed of a side passage 30B and has a detour 38.
One end of A opens to the bypass passage 36, and the side passage 30B opens to the vacuum vent 31, so that the auxiliary vacuum vent 38 bypasses the valve seat 30A and communicates the bypass passage 36 and the vacuum vent 31. It is something that makes you

Next, its operation will be explained.

The movable mold 2B and the fixed mold 2A are closed to form the gear bit 1, and the end of the spool 30 enters the fixed mold 2A,
With the plunger tip 5 opening the pouring hole 4, molten metal flows into the injection cylinder 3. At this time, the valve body 32 is in the valve body storage chamber 33 and the valve seat 30A is held open.

Next, when the plunger tip 5 moves to the left within the injection cylinder sleeve 3, low-speed injection is started, and during low-speed injection, the inside of the injection cylinder 3 is filled with molten metal, and at the end of low-speed injection, the runner 7 is also filled with molten metal. be done.

At this time, inside the cavity 1, there is a gas vent groove 37° and a bypass path 36. Valve seat 30A, vacuum vent 31 and bypass passage 36. Sub-vacuum vent 38. Vacuum vent 31
and are connected to the vacuum source P, so the pressure is reduced.

Immediately before the cylinder tip 5 shifts to high-speed injection (immediately before the end of low-speed injection), the limit switch 34 detects the position of the plunger tip 5 immediately before shifting to high-speed injection, and based on this output signal, the air cylinder An actuator 35 such as a hydraulic cylinder is operated to move the valve body 32 upward and close the valve seat 30A.

Therefore, from just before transition to high-speed injection by the plunger tip 5 to during high-speed injection, the gas vent groove 37. The bypass path 38 and the vacuum vent 31 are blocked and held by the valve seat 30A.

Next, when the plunger tip 5 further moves to the left within the injection cylinder sleeve 3 and enters high-speed injection, the valve seat 30A is already closed and held by the valve body 32, as described above.
The gas such as the mold release agent generated in the cavity 1 is discharged from the sub-vacuum vent 31 through the vacuum vent 31.
Furthermore, during this high-speed injection, the vacuum pressure of the vacuum source P is applied to the inside of the cavity 1 to evacuate the vent 31. Sub-vacuum vent 38. The gas is introduced through the exhaust passage 36 and the gas vent groove 37 to maintain a desired vacuum state within the cavity 1.

After the high-speed injection is completed, the molten metal in the cavity 1 is solidified by a ball, the movable mold 2B is opened, and the spool 30 including the valve body 32 is moved out of the mold.

Incidentally, if the number of sub-vacuum vents 38 is plural, the degassing effect during injection is improved, and the inside of the cavity 1 is particularly reduced during high-speed injection when the vacuum evacuation pen 31 is closed by the valve seat 30A and the valve body 32. The deterioration of the degree of vacuum could be suppressed.

〔Effect of the invention〕

The vacuum die casting apparatus according to the present invention has the following effects.

■ Since the valve seat is closed with the valve body immediately before the transition from low-speed injection to high-speed injection, gas from the release agent generated in the cavity due to high-speed injection and fine particles of molten metal will not adhere to the valve seat, and the valve seat will be prevented from adhering to the valve seat. Good sealing performance of the valve body can be maintained, and the valve body will not come into close contact with the valve seat and the opening performance will not deteriorate.

■ Even during high-speed injection, the inside of the cavity is still evacuated through the sub-vacuum vent, so even if there is a slight leak from the mold mating surface, the degree of vacuum inside the cavity will not deteriorate and it will work fine. A vacuum condition inside the cavity can be maintained.

Furthermore, since the gasified mold release agent is actively discharged to the outside from the sub-vacuum vent, there is no residual gas in the cavity, which prevents air bubbles from entering the product. Moreover, the surface of the product could be maintained uniformly without discoloration.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a main part showing a conventional vacuum die-casting device, Fig. 2 is a longitudinal cross-sectional view of a main part showing another conventional vacuum die-casting device, and Fig. 3 is an implementation of the vacuum die-casting device according to the present invention. FIG. 3 is a vertical cross-sectional view of a main part showing an example. 1, Cavity 2A, Fixed mold 2
B, Movable mold 3, Injection cylinder sleeve 4, Pouring hole 5, Plunger tip 30, Spool 30A, Valve seat 31
,,,,Vacuum vent 32. ,,,valve body 33,,,
, Valve body storage chamber 36, Bypass path 3B, Sub-vacuum vent 38A, Detour path 37, Gas vent groove

Claims (2)

[Claims] (1) In a vacuum die-casting device that maintains the inside of the cavity in a vacuum and injects the molten metal inside the injection cylinder sleeve into the cavity with a plunger tip, a spool that is arranged to move forward and backward within the mold; A vacuum suction vent is drilled, one end is connected to the vacuum source, and the other end is opened to a valve seat provided at the end of the spool entering the mold; and stored in a valve body storage chamber provided in the mold. and a valve body that is operated by an actuator to open and close the valve seat; one end opens into a gas vent groove that bypasses the side of the valve body storage chamber and opens into the cavity, and the other end opens near the valve seat. a bypass passage to be opened; a sub-vacuum vent that communicates the bypass passage and the vacuum vent by bypassing the valve seat; In addition to creating a detour with multiple bends with gaps, the actuator operates the valve body to close the valve seat just before the cylinder tip transitions from low-speed injection to high-speed injection, and during high-speed injection, the valve body closes the valve seat. Vacuum die-casting equipment that is closed and held. (2) The vacuum die-casting apparatus according to claim 1, wherein there is a plurality of sub-vacuum vents each formed of the tortuous path.