JPH0815651B2 - Degassing device for mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold degassing device for extracting gas from a mold cavity during injection molding by an injection molding device such as a die casting machine or an injection molding machine. is there.

[Prior Art] Conventionally, in an injection molding device such as a die casting machine,
When the melt is injected and filled into the cavity at high speed and high pressure, the gas in the cavity may not be completely exhausted and a cavity may be generated in the product.

Therefore, the applicant of the present invention has developed a mold degassing device capable of discharging a large amount of gas in a short time.

The degassing device disclosed in Japanese Examined Patent Publication No. 59-310 includes a member such as a tension spring that biases the valve in the closing direction and a member such as a compression spring and a ball that locks the valve in the closed position. When the melt comes, it closes the valve against the locking force of a member such as a ball, and when the first melt reaches the valve, the valve is quickly and reliably opened. Can be closed.

[Problems to be Solved by the Invention] However, such a conventional gas venting device is not necessarily satisfactory in that the locking force at the closed position of the valve is maintained for a long period of time. That is, if the valve is repeatedly opened and closed in each injection cycle, the ball and the leaf spring and the contact portion with these are worn, and the valve is closed before the melt comes due to the reduction of the locking force, There was a risk that degassing would be impossible. On the contrary, if the contact surface of the ball is roughened or deformed, the locking force at the valve open position becomes stronger, and even if the melt comes, the locking force exceeds the collision force and the valve will not close. If the melt enters the valve chamber, or because the collision force of the melt acting on the valve is small, it takes time for the valve to close even if the lock is released, and the melt enters during that time. There was a problem of being lost.

[Means for Solving Problems] In order to solve such problems, according to the present invention, a piston that slidably fits into the inner hole of the spool is fixed to the end of the valve rod opposite to the valve body. The piston rod side chamber, which is the side chamber of the piston, and the rod-side end surface of the piston can be opened and closed by the piston lower end outer peripheral portion by moving the valve rod forward and backward, and the piston head-side chamber, rod-side chamber, and piston Each of the ports communicating with each of the rod-side end surface portions of was and the pressure fluid source were connected by piping having a switching valve.

However, with this alone, if a malfunction occurs and working fluid such as compressed air leaks from the switching valve that communicates with the end surface of the piston on the rod side, the working fluid that leaks causes the piston rod to move to the side of the piston rod. When pressure is applied to the end surface and the pressure becomes large, there is a risk that the piston may be lifted and the valve body may be closed when it should not be closed.

Therefore, in the present invention, in order to ensure reliability and safety, by opening and closing the valve body, the end surface portion on the piston rod side and the hole for discharging the leaked working fluid communicating with the outside air portion provided in the spool are provided. A hole or groove for opening and closing the space is provided in the piston or the valve rod.

[Operation] Until the molten material injected into the cavities reaches the degassing hole, at least the rod side chamber of the piston is pressurized and the valve is opened, and the piston rod side end surface is held in a state in which no fluid pressure acts. So the gas in the cavity is
It is discharged from the discharge hole through the valve opening portion and the spool inner hole.
During injection, the melt reaches the valve opening and collides with the valve bottom,
Or, if fluid pressure acts on the end surface of the piston on the rod side and the piston moves up, the valve moves in the closing direction.However, if the valve moves slightly, fluid pressure acts on the end surface of the piston on the rod side and the valve closing direction becomes large. A force is generated and the valve is rapidly closed to keep the valve closed.

If the valve body is opened, a malfunction should occur, and if working fluid such as compressed air leaks from the switching valve communicating with the end surface of the rod side of the piston, the leaking working fluid should be When the valve body is open, it opens and closes between the rod-side end surface of the piston and the hole in the spool that communicates with the outside. Since the hole or groove communicates with the outside air, no pressure builds up on the end surface of the piston on the rod side, and the valve body does not close carelessly.

During the injection operation, when the melt acts on the valve element and the valve element begins to close and the piston begins to lift, the working fluid in the rod side chamber of the piston flows into the end surface of the piston rod side and acts. Between the end surface of the piston rod side and the hole for discharging the leaked working fluid communicating with the outside air provided in the spool, the hole or groove provided in the piston or the valve rod is also lifted to close it. The working fluid never flows out.

[Embodiment] FIGS. 1 to 4 show an example in which a die degassing apparatus according to the present invention is applied to a die casting machine. FIG. 1 is a longitudinal sectional view of the die casting machine, and FIG. Fig. 3 is a side view and a pneumatic circuit diagram, Fig. 3 is a partially cutaway side view of the gas venting device and a die for carrying it out, and Fig. 4 corresponds to Fig. 1 where the gas venting device is separated from the die. FIG.
However, in FIG. 1, FIG. 2, and FIG. 4, the piston portion is provided with a hole 80 and a groove 81 as shown in FIG. 11 and FIG. 12, which will be described later. Omitted. The same applies to FIGS. 5 to 10 and 15 described later.
In the figure, a cavity 4 is formed in a dividing surface 3 which is a joint surface between the fixed mold 1 and the movable mold 2 shown in a mold clamped state, and a cavity 4 is fixed in the cavity 4 from an injection sleeve (not shown). The molten metal 7 is injected and filled through the sleeve portion 5 and the gate 6. Reference numeral 8 denotes a product extruding device that extrudes the product obtained by solidifying the molten metal 7 from the cavity 4 of the movable mold 2 after the mold is opened. A spool hole 11 that communicates with the cavity 4 by a gas vent passage 9 and a gas vent groove 10 is opened to the outside at the upper end of the split surface 3 of the molds 1, 2. The bypass 12 that branches off from the middle and detours is the gas vent groove 10
Is communicated with the opening of the spool hole 11.

On the bracket 13 fixed to the upper surface of the fixed mold 1,
The fluid pressure cylinder 14 is fixed concentrically with the spool hole 11, and the flange 15a, which is the working end of the piston rod 15 that advances and retracts due to the fluid pressure, has a spool 17 of the degassing device indicated as a whole by reference numeral 16. A holder 18 that holds the upper end is fixed, and the spool 17 is held by a presser foot 19 and a bolt 20.
It is fixed at 18. The spool 17 is formed in a cylindrical shape with a bottom, and a step portion 17a is provided at the lower end thereof, and the forward and backward movement of the piston rod 15 raises and lowers the entire degassing device 16 so that the step portion 17a engages with the spool hole 11. Mating or spool hole 11
It is configured to be separated from.

FIG. 5 is a sectional view of a main part of the gas venting device, and the gas venting device 16 will be described below with reference to FIGS. 1 to 5. The spool 17 is divided into a member 17b and a member 17c, and a flange of the valve guide 21 fitted in the inner hole 17d is held between them, and in this state, the members 17b, 17c and the valve guide 21 are integrated. Has been converted. Reference numeral 22 denotes a piston located above the valve guide 21 and slidably fitted in an inner hole 17h of the member 17b. The center screw hole of the piston 22 has an inner hole 21 of the valve guide 21.
A threaded portion of a valve rod 23 that is fitted in a so that it can move back and forth is screwed into and integrated with the valve rod 23, and a valve body 24 is integrally formed at the lower end of the valve rod 23. On the other hand, a valve seat 17e is formed at the lower opening end of the spool 17, and the valve body 24 and the valve seat 17e are the first
The molten metal 7 that rises in the degassing groove 10 from the open state shown in the drawing is configured to be pushed up by the valve body 24 and rise to the closed state. In the valve open state shown in the drawing, the valve body 24 engages with the opening step portion of the gas vent groove 10 to close it. Reference numeral 17f in FIG. 2 denotes a discharge hole for discharging the gas introduced to the valve chamber 17g of the spool 17 through the bypass 12 in the valve open state to the outside.

Ports 26a and 26b are opened in the head side chamber 25 of the piston 22 provided at the center of the upper portion of the member 17b of the spool 17, and the port 26b is a switching valve having a solenoid SOL-A.
It is connected to a compressed air source 30 via a pipe 29 having a pressure reducing valve 28 and a pressure reducing valve 28. On the other hand, a flange 22a is formed on the rod side of the piston 22, and when the lower surface of this flange 22a is pressed against the O ring 33 fitted on the upper portion of the valve guide 21 when the valve is open, the O ring It can block the flow of compressed air inside and outside 33. O-ring 33 is valve guide 21
It is fixed by the semi-existing groove on the upper part of and the inner peripheral surface of the member 17b and does not come off. Then, the port 34 provided in the rod-side chamber 31 provided below the outer periphery of the side surface of the piston
Is connected to the compressed air source 30 via a pipe 37 having a switching valve 35 having a solenoid SOL-B and a pressure reducing valve 36, and is connected to the rod side chamber 31 inside the O-ring 33 on the rod side. Port 38 to end face is solenoid SOL
It is connected to the compressed air source 30 via the pressure reducing valve 36 and a pipe 40 having a switching valve 39 having -C.

 With such a configuration, the following control can be performed.

i) Opening operation of the valve When the solenoid SOL-A is energized and the solenoids SOL-B and SOL-C are de-energized, compressed air will be discharged through the port 26b.
And 26a flow into the head side chamber 25 to push down the piston 22, the lower surface of the piston 22 is pressed against the O-ring 33, and the valve seat 17e is opened.

ii) Holding the valve open After the valve has been opened, first energize the solenoid SOL-B and then deenergize the solenoid SOL-A. In this state, the compressed air flows into the rod-side chamber 31, passes through the gap between the piston 22 and the inner hole 17h of the member 17b, and the head-side chamber 25.
However, back pressure is hardly generated in the head side chamber 25 because it is discharged through the switching valve 27 with almost no pipe resistance. At this time, the compressed air does not flow from the rod side chamber 31 into the inside of the O-ring 33 which is in contact with the lower surface of the piston 22, and the compressed air before the closing operation of the valve is the valve rod 23 and the valve guide. No pressure is generated because it leaks through a gap between the inner hole 21a of 21 and is discharged to the outside through a hole 80, a groove 81, etc., which will be described later with reference to FIG. 11 and the like.
If the air pressure of the rod side chamber 31 at this time is P _R and S ₁ is the area shown in FIG. 5, the valve opening holding force represented by P _R · S ₁ acts on the valve to maintain the valve open state. are doing.

closing energized solenoid SOL-B and SOL-C of iii) valve, when the solenoid SOL-A in the non-energized state, the air pressure P _R is applied to the lower surface of the piston 22, the piston 22 is pushed up valve upwards Closes. If S ₂ is the area shown in FIG. 5, the valve holds the valve closed state by the force given by P _R · S ₂ . Further, in the opened holding state, the open retaining force than the force acts in the closing direction of the valve valve slightly moved, the lower surface of the piston 22 is moved away from the O-ring 33, the air pressure acts on the piston entire lower surface, P _R The piston 22 rises rapidly due to the force given by S ₂ , and the valve seat 17
e is quickly closed and the valve closed state is maintained.

The operation of the die degassing device configured as described above will be described. After the molds 1 and 2 are clamped, the fluid pressure cylinder 14 operates to lower the entire degassing device, and the step 17a of the spool 17 fits into the spool hole 11 as shown in FIG. Next, after the above-described valve opening operation, the valve is kept open. At this time, the lower surface of the valve body 24 closes the upper end opening of the gas vent groove 10, and the gas vent groove 10 and the spool valve chamber 17g communicate with each other by the bypass 12 and the valve opening portion. In this state, when the molten material is injected into the injection port of the injection sleeve and the plunger of the injection cylinder is advanced, the molten metal 7 is injected and filled into the cavity 4 through the fixed sleeve portion 5 and the gate 6. Accordingly, the gas in the cavity 4 hits the lower end of the valve body 24 through the gas vent passage 9 and the gas vent groove 10, and the bypass 12, the valve body 17g.
And is discharged from the discharge hole 17f. At this time, the valve opening retention force represented by P _R · S ₁ is determined so that the valve body 24 will not be closed by the gas. Then, the molten metal 7 is almost filled in the cavity 4 and then rises in the gas vent groove 10 to hit the lower surface of the valve body 24 together with the gas. At this time, the mass of the molten metal 7 is much larger than the mass of the gas, and a large inertial force is exerted on the valve body 24.
Since it acts on the lower surface of the valve body 24, the valve body 24 is flipped up. In this way, the valve body 24 moves slightly upward and the piston
When the lower surface of 22 separates from the O-ring 33, the compressed air in the rod side chamber 31 enters the inside of the O-ring 33 through the gap between the piston lower surface and the O-ring 33, and the force represented by P _R · S ₂ described above is applied to the piston. It acts on the lower surface of 22 and causes piston 22 to rise rapidly. As a result, the valve seat 17e is closed by the valve body 24 and the valve closed state is maintained, so that the molten metal 7 is blocked from moving at the position of the valve body 24.

In this way, the valve body 24 is connected to the degassing groove 10 and the bypass 12
After the molten metal 7 is pressurized and cooled for a predetermined time in a state in which and are closed, when the entire gas venting device 16 is raised by the fluid pressure cylinder 14 as shown in FIG. 4, the cavity 4, the gas venting groove 10, and The valve body from the solidified material 41 solidified in the bypass 12
24 separates, but at this time, the upward movement of the valve body 24 is hindered by the separation resistance between the valve body 24 and the solidified material 41, and the spool 17
The valve body 24 opens after a delay from the rise of the valve, and the valve open state is maintained by the action of the air pressure. After cooling, the product in the cavity 4 is opened and the product is extruded by the product extruding device 8. FIG. 4 shows a state where the solenoid SOL-C is subsequently energized and the valve body 24 is closed.

FIGS. 6 to 15 are sectional views of the essential parts of the degassing device showing another embodiment of the present invention corresponding to FIG. First, in the structure shown in FIG. 6, a labyrinth groove 42 is formed on the inner peripheral surface of the inner hole 17h of the spool 17 on which the piston 24 slides.
Is provided, and by doing so, leakage of compressed air can be reduced. Next, as shown in FIG.
The O-ring 4 is inserted in the groove provided on the inner peripheral surface of the inner hole 17h of the spool 17.
By interposing 3, the leakage of compressed air can be further reduced. O-ring
In the case where 33 is provided, this may be fixed to the lower surface side of the piston 22. Further, as shown in FIG. 8, a plate-like rubber packing 44 is inserted as a seal member instead of the O-ring 33, and this may be a metal packing such as copper or lead instead of rubber. Further, the one shown in FIG. 9 is one in which the O-ring 33 is not provided, the valve guide 21 is provided with the step portion 21b, and the outer peripheral surface of the flange 22a is fitted to the step portion 21b. Can also obtain a similar function. Further, in FIG. 10, the O-ring and the packing are not used, and the flange 17h and the inner peripheral surface of the upper portion of the valve guide 21 are tapered and fitted together. FIG. 11 shows one embodiment of the main part of the present invention,
Similar to that shown in FIG. 9, a step portion 21b is provided on the valve guide 21, and the outer peripheral surface of the flange 22a is fitted to the step portion 21b. However, when the valve is held open, a slight leakage from the fitting portion occurs. In order to prevent the compressed air from pushing up the piston 22, the compressed air is provided in the piston 22 on the bottomed hole 80 provided in the axial direction from the rod-side end face portion of the piston 22 and on the outer periphery of the piston 22 communicating with this. The groove 81 and the groove 82 provided in a part of the inner hole surface portion where the outer peripheral surface of the piston 22 of the member 17b of the spool 17 is slidably fitted, and the hole communicating with the groove 82 and communicating with the outside.
It is designed to be discharged to the outside through 83. That is, in the structure shown in FIG. 11, the rod-side end surface portion of the piston and the groove 8 communicating with the outside provided in the spool 17 are provided.
2.The piston 22 is provided with a hole 80 and a groove 81 for opening and closing between the hole 83 and the hole 83.After the piston 22 is raised and the valve is closed, the communication between the groove 81 and the groove 82 is established as shown in FIG. Cut off, rod side chamber 31
The fluid inside is not discharged to the outside. Further, FIG. 13 shows another embodiment of the main part of the present invention, in which the compressed air is spooled so that the compressed air slightly leaking from the fitting part does not push up the piston 22 when the valve is held open. Valve guide 21 forming part of 17 and hole 84 and valve rod 2 provided in member 17c
It is designed to discharge through the groove 85 provided in 3. That is, in the structure shown in FIG. 13, a valve rod is provided with a groove 85 that opens and closes a part of the hole 84 that communicates with the end surface of the piston on the rod side and communicates with the outside provided in the spool 17.
It is installed in 23, and after the piston 22 rises and the valve closes,
As shown in FIG. 14, the communication between the hole 84 and the groove 85 is cut off, and the compressed air in the rod side chamber 31 is not discharged to the outside.

Although the piston 22 is provided with the flange 22a in the above embodiment, it may be a piston without a flange as shown in FIG. In this case, when the valve is held open, compressed air is supplied to the head-side chamber 25 to provide the valve open-holding force. However, the opening holding force of the valve at this time must be smaller than the force that acts on the lower surface of the piston when the valve is closed and tries to close the valve.

That is, when the valve is held open (when the valve is open), when the valve is closed (when the valve changes from the open state to the closed state), and when the valve is kept closed (when the valve is closed). The pressure in the side chamber 25 is set to be smaller than the pressure in the rod side chamber 31, and the pressure in the rod side chamber 31 acts on the lower surface of the piston 33 during the valve closing operation so that acceleration in the valve closing direction is applied to the valve. .

In the above embodiment, the valve body 24 is closed only by the inertial force of the molten metal. However, in some cases, the valve body 24 is closed by an electric command or the like during injection to close the valve body 24. You can also do so.

In the embodiment described above, the gas discharge hole 17f provided in the spool 17 is shown in the state of being open to the atmosphere. However, this is the case where a vacuum suction device is connected to the discharge hole 17f and the inside of the cavity 4 is closed. It is also possible to inject the molten metal in a vacuum state.

[Effects of the Invention] As is apparent from the above description, according to the present invention, in the mold degassing device, the piston that slidably fits the inner hole of the spool at the end of the valve rod opposite to the valve body. Fixed,
The piston rod side chamber, which is the side chamber of the piston, and the rod side end surface of the piston can be opened and closed by the piston lower end outer peripheral portion by the movement of the valve rod, and the piston head side chamber, the rod side chamber, and the piston rod. By connecting each port communicating with each of the side end face parts and the pressure fluid source with a pipe having a switching valve, the valve open state is maintained by the fluid pressure during degassing, and the molten metal collides with the valve body. When the valve body moves slightly in the closing direction, fluid pressure acts on the end surface of the piston on the rod side, and a large force is generated in the direction to close the valve body, so that the valve body can be closed rapidly and reliably. There is no fear that the locking portion will be worn out unlike the locking device due to the above, the holding force at both the open and closed positions can be reliably maintained for a long period of time, and durability and reliability are significantly improved. Further, since the valve always operates reliably and the gas is surely discharged at the time of injection, it is possible to surely and easily obtain a high quality and high strength injection product having no void. In addition, the number of parts is reduced compared to when mechanically holding the valve in the open position, maintenance is easier, and the holding force at the valve open position can be adjusted only by adjusting the fluid pressure. , Easy to adjust.

Further, in the present invention, a hole or groove for opening and closing between the rod-side end surface portion of the piston and the hole communicating with the outside provided in the spool by opening and closing the valve body is provided in the piston or the valve rod. If your body is open,
Even if a malfunction occurs and working fluid such as compressed air leaks from the switching valve communicating with the end surface of the piston rod side, and the leaked working fluid flows to the end surface of the piston rod side, the valve element opens. When the piston rod or valve rod is open, a hole or groove that opens and closes between the rod-side end surface portion of the piston and the hole that communicates with the outside provided in the spool is open to the outside air portion. No pressure builds up on the side end faces, and the valve body does not close inadvertently.

During the injection operation, when the melt acts on the valve body and the valve body begins to close and the piston begins to lift, the working fluid in the rod side chamber of the piston flows into the rod side end surface of the piston and acts. At times, between the rod-side end surface portion of the piston and the hole for discharging the leaked working fluid leading to the outside air portion provided in the spool, the hole or groove provided in the piston or the valve rod is also lifted, Since it is closed, the working fluid does not flow out.

[Brief description of drawings]

1 to 15 show an embodiment of a mold degassing apparatus according to the present invention. FIG. 1 is a longitudinal sectional view of the same, and FIG. 2 is a longitudinal sectional view of the same main portion and a pneumatic circuit diagram. FIG. 3 is a partially cutaway side view of a mold degassing device and a mold in which the degassing device is implemented, and FIG. 4 shows a part of the degassing device separated from the mold.
FIG. 5 is a vertical cross-sectional view corresponding to the drawings, FIG. 5 is a vertical cross-sectional view of an essential part of a mold degassing device, and FIGS. 6 to 15 are mold gas showing other embodiments of the present invention. It is a longitudinal cross-sectional view of the main part of the punching device. In particular, FIGS. 11 to 14 are longitudinal sectional views showing an embodiment of the main part of the present invention. 1 ... Fixed mold, 2 ... Movable mold, 4 ... Cavity, 11 ... Spool hole, 16 ... Mold degassing device, 17 ... Spool, 17d ... Inner hole, 17e ... Valve Seat, 17f …… Discharge hole, 22 …… Piston, 22a …… Flange, 23 …… Valve rod, 24 …… Valve body, 25 …… Head side chamber, 26a, 26b, 34,38 …… Port, 27,35 , 39 …… Switching valve, 29,37,40 …… Piping, 30 …… Compressed air source, 31 …… Rod side chamber. 80,83,84 …… holes, 81,82,85 ……
groove

Claims (1)

[Claims] 1. A spool having a bottomed cylindrical shape, having a gas discharge port on a wall surface and having an opening end attached to a spool hole portion of a mold, and a valve rod provided inside the spool so as to be capable of advancing and retracting. And a valve element provided at the tip of the valve rod to open and close the opening end of the spool by advancing and retracting the valve rod, and through the discharge hole through the open spool opening end and the spool inner hole. In a mold degassing device for discharging gas in a mold cavity, a piston that slidably engages with an inner hole of a spool is fixed to an end of the valve rod opposite to the valve body, and the valve rod is moved back and forth. It is configured such that the space between the rod side chamber, which is the side chamber of the piston, and the rod side end face portion of the piston can be opened and closed by the piston lower end outer peripheral portion by the movement, and the head side chamber of the piston, the rod side chamber, and the rod side end face of the piston. Department Connect each port communicating with each to the pressure fluid source with a pipe that has a switching valve, and open and close the valve body to slidably fit the rod-side end surface of the piston and the outer peripheral surface of the piston. Is provided in a part of the inner hole surface side of the spool and opens and closes between the groove (82) whose outer peripheral side communicates with the outside through the hole (83), in the axial direction from the rod side end of the piston. The hole (80) and the hole (80)
A groove (81) provided on the outer peripheral surface of the piston at the upper end of the piston, or in the middle of a hole (84) communicating with the rod-side end surface of the piston and communicating with the outside provided in the spool. A mold degassing device, characterized in that a groove (85) for opening and closing a part is provided in the valve rod.