JPS5846385B2 - Non-porous die casting method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-porous die casting process and apparatus.

Conventionally, a die casting machine fills the mold cavity with oxygen or other reactive gas to expel the air in the cavity, and then performs casting to cause the reactive gas and molten metal to react, producing a cast product with no voids. A casting method is known, which is called the non-porous die casting method.

In order to employ this non-porous die casting method, a passage must be provided from the outside of the mold to the inside of the cavity, and a reactive gas must be supplied thereto.

However, if such a reactive gas supply passage is provided, the molten material to be injected into the cavity at high speed and high pressure during injection molding may be ejected out of the mold through this passage. Put it away.

Therefore, in the past, a valve was provided at the opening end of the passage, and a cylinder or the like was used to close the valve in synchronization with the injection operation, thereby preventing the molten material to be injected from ejecting outside the mold. was adopted.

However, if such a structure is adopted, it is difficult to get accurate timing, and if you try to get reliable timing, there will inevitably be a time loss between the valve opening/closing operation and injection molding, which will reduce injection molding efficiency. Moreover, since the valves are opened and closed by other driving means, there is a risk that a failure of the driving means could lead to a major accident.

The object of the present invention is to provide a non-porous die casting method and apparatus that can supply a reactive gas into the mold cavity and prevent the molten material to be injected from spewing out of the mold during injection. It is on offer.

In order to achieve the above object, in the present invention, a passage leading from a reactive gas supply source outside the mold to the mold cavity is opened by the action of a valve, and after filling the cavity with reactive gas, injection is performed. A configuration was adopted in which the inertial force of the molten material to be injected that had advanced from inside the cavity during injection was applied directly to the valve, thereby moving the valve and directly blocking the passage with the valve.

Hereinafter, the present invention will be described in detail together with embodiments shown in the drawings.

The figure is for explaining the schematic structure of the main parts of the apparatus to which the method of the present invention is applied. A cavity 2 into which the molten material to be injected is injected is formed in the dividing surface, and a first passage 3 for gas supply and discharge communicating with this cavity 2 is formed in the mating surface of the mold.

From the middle of this passage 3, bypasses 4, 4, which are a pair of left and right second passages for supplying and discharging gas, are formed along the mating surfaces of the molds.

At the tip of the passage 3, there is a valve 5, which has one end face that can receive the inertial force of the injected melt advancing through the passage 3 and intersects with the axial direction of the passage 3, such as at a right angle. It is arranged to be slidable in the axial direction.

A cylindrical body 6 having a valve seat 6C at its lower end is fitted into a half hole provided in the dividing plane between the fixed mold 1 and the movable mold, and the valve 5 is inserted into this cylindrical body 6. It is slidably fitted into the

A stopper 5a is formed at the upper end of the valve 5, and a valve head 5b is formed at the lower end, and this valve head 5b faces the outer end of the passage 3. The limit of movement is restricted by contacting the partition wall 6a.

A spring 7 is elastically mounted between the stopper 5a and the inner surface of the upper end of the cylindrical body 6, and provides a force for pushing the valve 5 and blocking the opening end of the passage 3 by the valve head 5b.

The other end of the bypass 4 opens to the rear side surface of the movement path of the valve 5.

Therefore, when the valve 5 is open as shown, the supply port 6b, which is the third gas supply/discharge passage provided on the side surface of the cylinder 6, and the bypass 4, which is the second passage, When the valve 5 slides in the axial direction and closes, the bypass 4 and the supply hole 6b can be shut off by the action of the face of the valve 5 and the valve seat 6c.

On the other hand, the tip of the cylindrical body 6 is connected to a cylinder 8 fixed to the fixed mold 1.
It is fixed to the tip of the rod 8a, and the cylinder body 6 itself can be moved forward and backward.

One end of a pipe 9 is connected to the supply port 6b, and the other end of the pipe 9 is connected to a reactant gas supply source 10 such as an oxygen cylinder.

A pressure reducing valve 11 is installed in the middle of the pipe 9. Pressure gauge 12. Solenoid valve 13
．． A variable throttle 14, a check valve 15, etc. are interposed.

Next, the operation of this embodiment configured as above will be explained.

First, after the mold is clamped, a detection signal from a limit switch or the like (not shown) is input to the solenoid valve 13, and the piping 9, which has been closed until now, is opened, causing a reaction such as oxygen gas to flow from the reactive gas supply source 10. Sexual gas is supplied into the cylinder 6 from the supply port 6b of the cylinder 6.

In this state, the valve 5 is moved to the passage 3 by the elastic force of the spring 7.
The opening end of the passageway 3 is blocked.

Therefore, the reactive gas that has entered the cylindrical body 6 is transferred to the bypass 4.
, 4, join in the passage 3, and are supplied into the mold cavity 2.

As the reactive gas is supplied, the air remaining in the mold cavity 2 is discharged from the hot water supply port on the injection sleeve side, and the inside of the cavity is filled with the reactive gas.

When supplying reactive gas into the cavity after mold clamping, place the injection plunger tip (not shown) behind the hot water supply port of the injection sleeve from the beginning and supply the reactive gas with the hot water supply port open. may be supplied into the cavity, or by first positioning the plunger tip near the tip of the injection sleeve in front of the hot water supply port of the injection sleeve to block the injection sleeve and begin supplying the reactive gas. Next, after the supply of reactive gas is started, the plunger tip may be moved back to a position behind the supply port of the injection sleeve in synchronization with the supply of reactive gas, and the hot water supply port may be opened.

First, with the plunger tip positioned near the tip of the injection sleeve, reactive gas can be injected into the cavity from the top of the cavity, and if the plunger tip is retreated as the reactive gas is injected, the reactive gas can be injected. Before injection begins, the original volume of air in the mold and injection sleeve is relatively small, and as the plunger tip retreats, this air is sucked into the injection sleeve and the reactive gas is also drawn into the cavity. The air inside the cavity will be sucked in and pushed by the reactive gas sequentially injected from the upper side of the cavity to the injection sleeve side, so the exchange of air and reactive gas inside the cavity will occur. The efficiency is improved and the cavity is easily filled with reactive gas.

Of course, in this case as well, the plunger tip is moved back beyond the hot water supply port, and a sufficient amount of reactive gas is injected until the reactive gas exits from the hot water supply port into the atmosphere.

When reactive gas fills the mold cavity, solenoid valve 1
3 is closed.

Thereafter, the molten material to be injected is supplied to an injection sleeve (not shown), and then the plunger is actuated to supply the molten material to be injected into the mold cavity 2.

At this time, the reactive gas in the cavity 2 reacts with the molten material to be injected and disappears, and does not remain as bubbles.

When the inside of the cavity 2 is filled with the molten material to be injected,
The molten material to be injected enters the passage 3, travels straight through the passage 3, and collides with the valve head 5b of the valve 5 with a large inertial force.

As a result, the valve 5 moves upward in the figure against the elastic force of the spring 7, and blocks the opening ends of the bypasses 4, 4 with the circumferential surface of the valve head 5b.

In this state, since both the passage 3 and the bypass 4 are blocked by the valve head 5b of the valve 5, the molten material to be injected does not eject outside the mold.

After the molten material to be injected has cooled in the cavity 2, the mold is opened, but just before the mold is opened, the cylinder 8 is operated in the opposite direction, and the cylinder 6 is pulled out together with the valve 5.
The bond between the solidified melt to be injected filling the passage 3 and the bypass 4 and the valve head 5b of the valve 5 is released.

Thereafter, the mold is opened, and the molded product in the cavity 2 and the solidified molten material in the passage 3 and the bypass 4 are separated from the fixed mold 1 while being attached to a movable mold (not shown). Eventually, the ejection pin performs a mold release operation.

Thereafter, injection molding is performed by repeating similar operations.

In the above embodiment, the solenoid valve 13 was closed when the cavity was filled with reactive gas, but this may be done immediately before the mold is opened.

As is clear from the above description, according to the present invention, the passage leading from the reactive gas supply source outside the mold to the mold cavity is opened by the action of a valve, and after the inside of the cavity is filled with the reactive gas, injection is performed. The inertial force of the injected molten material that has advanced from inside the cavity during injection is applied directly to the valve, and the passage of the reactant gas is directly blocked by moving the valve. Inside the cavity of
In addition to ensuring a reliable supply of molten material, the injection of molten material to the outside of the mold is completely prevented.Moreover, the movement of the valve is not caused by another driving source, but by the inertia of the molten material itself. Since this is done by force, there is no need to adjust the timing of closing the valve, and the reaction time of the valve is fast, which significantly increases the injection molding cycle and allows efficient production of non-porous die-cast products.

In this invention, the inertial force of the molten metal, which is the molten material to be injected, is applied directly to the valve that opens the second passage leading to the outside of the mold, thereby directly blocking the second passage during gas discharge. This allows the valve to be tightened quickly and with great force.

That is, in this invention, the molten metal that has passed through the first passage to the bottom of the valve collides with the bottom of the valve, thereby directly hitting the valve. The kinetic energy of the molten metal due to force, that is, the dynamic pressure of the molten metal, is used to directly line the valve.

In this case, the force for closing the valve is proportional to the square of the speed at which the molten metal collides with the bottom surface of the valve, so it is a very large force.

Since the molten metal can be applied to the entire lower surface of the valve, the force to close the valve is large, and
Since the passage through which the gas is being discharged is directly connected by the valve, the valve itself has a simple structure and is relatively light in weight, and the valve can be closed quickly.
The passageway during gas discharge can be quickly, reliably and easily closed.

In addition, in this invention, the time required to close the valve is an extremely short time of about 5 m5 ec.

In addition, in this invention, the valve during gas discharge is directly and instantaneously closed by the action of the inertia of the molten metal.
There is no need to create resistance by narrowing the entrance or middle of the second passage, also called a bypass, which leads from the first passage to the side of the valve movement path, and there is no need to make this second passage longer than necessary. Since the passage can be simplified and made relatively wide, the degassing capacity is also large, and degassing can be performed reliably.

In the first place, in order to sufficiently vent gas from the mold cavity during injection, prevent the formation of cavities in the injected product, and continue to perform a satisfactory injection operation, the gas must be sufficiently vented through the valve part, but the molten metal must be released to the outside. It is necessary to prevent it from leaking, but
To do this, keep the valve open until the molten metal approaches the valve seat, which is the opening part of the valve, through the second passage where the gas is being discharged, and when the gas has fully escaped, quickly close the valve. That is, it is necessary to tighten in an extremely short period of time, but in the present invention, as described above, this operation can be performed reliably and easily, and can be performed repeatedly for each injection.

Further, since the valve of the present invention is simple and consists of only one valve, the structure of the entire degassing device is relatively simple, and maintenance and inspection are easy.

In addition, if a seat type valve is used that is pressed against a valve seat with an inclined surface, the seal will be reliable, the operating resistance will be small, the molten metal will not get stuck, the valve will not be affected by thermal expansion, and the operation will be stable. Moreover, it is reliable, has a relatively simple structure, is easy to manufacture, and is inexpensive.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a schematic diagram showing one embodiment of an apparatus used to carry out the method of the present invention. 1... Fixed mold, 2... Cavity,
3... Passage (first passage), 4... Bypass (second passage), 5... Valve, 6... Cylindrical body, 6a...
・Supply port (third passage), 7... Spring,
8... Cylinder, 10... Reaction gas supply source, 13... Solenoid valve.

Claims (1)

[Scope of Claims] 1. A passage leading from a reactive gas supply source outside the mold to a cavity in the mold is opened by the action of a valve, and after filling the cavity with reactive gas, injection is performed, and during injection, A non-porous die casting method in which the inertial force of the molten material to be injected advancing from inside the cavity is applied directly to the valve, thereby moving the valve and directly blocking the passage with the valve. 2. At the separation surface of the mold, a valve is provided at the end of the first passage for gas supply and discharge led from the cavity, and is slidable in the axial direction of the end of the first passage,
A second passage for gas supply and discharge is provided that communicates from the first passage to a side surface of the valve movement path, and a mold is provided from the side surface of the valve movement path which is an end of the second passage. providing a third passageway for gas supply and discharge leading to the outside, the valve providing communication between the second passageway and the third passageway by sliding thereof;
The valve has a face part capable of shutting off, and one end face receiving the inertial force of the molten material to be injected advancing through the first passage is provided so as to intersect with the axial direction of the end of the first passage. a non-porous die-casting apparatus, wherein the third passage is connected to a source of a reactive gas supplied into the cavity.