KR100235163B1 - Valve assembly for venting die casting moulds - Google Patents

Abstract

A vent valve assembly for use in a die casting mold for venting a mold cavity. The vent valve assembly comprises a block unit, a tube (block unit tube) in the block unit configured to form an extension of the vent pipe of the die casting mold, at least one valve piston mounted in the block unit for venting the block unit tube; At least one actuating piston mounted in the block unit and exposed to the block unit tube to react with the fluid pressure in the block unit tube against the reaction force generating means, and the valve piston or each valve piston is an actuating piston or respective actuating piston And a connection located between one valve piston or each valve piston and the other working piston or each working piston to be driven by the movement of the. The axis of the valve piston or each valve piston and the actuating piston or each actuating piston is substantially parallel.

Description

Ventilation Valve Device for Die Casting Mold

1 is a vertical sectional view of a valve arrangement according to the invention in which the valve pistons are in an open position.

2 is a vertical section of the valve arrangement according to the invention with the valve pistons in the closed position.

FIG. 3 shows one of the two block components of the valve arrangement seen in the direction of arrow III-III of FIG.

4 is a front view of another block part seen in the direction of arrows IV-IV of FIG. 1;

FIG. 5 is an axial sectional view of the valve piston shown in comparison with FIGS. 1 and 2 and a cylinder containing the valve piston.

* Explanation of symbols for main parts of the drawings

1, 2: block part 3: bolt

4: fixing bolt 5: half

7: vent tube 8: tube extension part

9: extension 10: working piston

11: shoulder 12: cylindrical space

13: electric piston 14: moving disk

15: piston rod 16: bore

17: pressure spring 18: annular groove

19: cylinder 20: valve piston

21: color 22: outlet

23: branch duct 24: chamber

25: piston head 26: outer head surface

27: flat part 28: pressure duct

29: chamber

The present invention relates to a vent valve assembly for use in a die casting mold.

Such vent valve assemblies are already known from the specification of Swiss Patent Nos. 306,274. In the case of the device disclosed in this specification, the motion transfer connection between the actuating piston and the valve piston is made by a rocking lever to which the two pistons are articulated. When the actuating piston moves, the locking lever rotates and correspondingly moves the valve piston to close or open the valve according to the degree of rotation of the locking lever.

In general, however, such conventional valve assemblies are only applicable to small valves suitable only for small mold mold cavities for small castings. However, even in this case, since the lever mechanism must have a high precision, this complicates the manufacturing process of the valve assembly and cannot fully prevent operational failure. Since the two pistons have guide cylinders with a constant axial length, the deviation of the locking lever slightly inclined from the position perpendicular to the axis of the cylinders can stress the piston guides. To avoid this, specific means are provided at the articulation points of the pistons to the locking lever to compensate for the reduction in the spacing of the pivoting points of the piston caused by the change in the angle of the locking lever projecting in a plane perpendicular to the piston axes. shall.

According to the present invention, a vent valve assembly for use in a die casting mold for venting a mold cavity is provided, the valve vent assembly comprising a tube in a block unit configured to form a block unit and an extension of the vent pipe of the die casting mold. Block unit pipe ＂), at least one valve piston mounted in the block unit for venting the vent pipe in use, and the block unit pipe, and arranged in the block unit to react to fluid pressure in the block unit pipe against the reaction force generating means. At least one actuating piston exposed to the block unit conduit and, in use, fluid pressure rise in the block unit conduit to actuate each actuating piston and each valve piston such that each valve piston shuts off the block unit conduit so that it is not vented. In order to ensure that each valve piston Copper to include a connecting portion located between the valve piston and the other end of each of each one working piston and the axis of each of said valve piston and the working piston are each characterized in that it is virtually parallel.

In a preferred embodiment, the transfer of motion between the actuating piston (s) and the valve piston (s) is made by a disc shaped member occupying the space between two contact surfaces on the valve piston (s). This space may be a groove occupied by a disc with radial movement. The design of the connection between each actuating piston and each valve piston can be made to ensure correct operation without requiring high precision in the design and manufacture of the parts. Furthermore, if the shape of the connection allows for any radial play of the interlocking parts of the two pistons or of the members fixed to or interacting with these pistons, stop operation due to thermal expansion of the interlocking parts. There is no need.

Nevertheless, if there is a very high thermal stress, one of the pistons may jam in the cylinder as the piston continues to heat up and expand beyond the receiving cylinder. In order to greatly mitigate this risk, in the case of a preferred form of embodiment of the vent valve assembly according to the invention, several arrangements are arranged side by side and interact with a disc shaped member protruding towards the valve pistons (as described above). Two actuating pistons are provided, the disc shaped member engaging between two contact surfaces on at least one valve piston. For the same purpose, instead of just one valve piston, it is possible to have several valve pistons, in which case a moving member, eg in the form of a moving disk, is actuated by a actuating piston or connected to actuating pistons. Is connected to all valve pistons. Depending on the number of actuation and / or valve pistons, their diameters can be made relatively smaller than the diameter of a single acting and / or valve piston, in order to assure good performance and to likewise allow the discharge of large quantities of gas from the casting mold. have. These small diameters allow the movement of the piston to be smaller than that of a larger diameter piston without jamming or blocking at high temperatures, so that the high flow metal under high metal pressure formed between the piston and the cylinder walls (highly fluid metal) is pressurized to reduce the risk of inactivating the valve. The provision of the plurality of actuating pistons and, if necessary, the valve pistons, can be reduced by the force required to return the pistons to their starting position, thanks to their easy mobility in the receiving cylinders. As a result, this only requires a relatively weak return spring, which eliminates the need for pins often used to mitigate the high ejection forces generated by large diameter actuating pistons.

In addition, it is also advantageous to dimension such an actuating and / or immersion depth of the valve piston, which is formed as a plunger, to be at least 1/4 of the piston diameter at the seal head end to prevent jamming or blocking of the piston. It is to be understood that this immersion depth is the axial length of the cylinder that houses the piston that can be moved into the cylinder walls that unseal the outer head face of the piston.

Thanks to this relatively deep immersion, the casting material comes into contact with the cylinder stars and the likewise large areas of the piston head, sending at least as much heat onto the cylinder as is sent to the piston. As a result, the enlargement of the cylinder diameter due to the temperature rise becomes equal to the enlargement of the piston diameter, so that the play of the initial wall between the piston and the cylinder is maintained. Therefore, only a small return force is sufficient to move the valve piston to the open position.

The invention will now be described by way of example with reference to the accompanying drawings.

In the case of the embodiment shown in the figure, the vent valve device consists of one block unit having two block parts 1, 2 joined together by bolts 3. This block unit is screwed onto the half part 5 of the die casting mold by the other fixing bolts 4 in a manner supported by the outer surface as shown in FIG. 4 with respect to the half part 6 of the die casting mold. .

In the case of the illustrated embodiment, the mold half 5 shown on the right side of FIGS. 1 and 2 is provided with a vent pipe 7 with a tube extension 8 in the block part 1 of the valve arrangement. The tube extension 8 has at its end an extension 9, through which the cylinders of the five actuating pistons 10 are opened (see FIG. 4). These actuating pistons are configured as plungers and at their ends facing the shoulders 11 located away from the extension 9 located in the cylindrical space 12 and functioning as stops defining the starting position of the actuating pistons. Equipped. An electric piston 13 that supports a rotatable disk 14 rotatable about the axis of the piston at the head end facing away from the actuating pistons 10 is axially slidable in the cylindrical space. For this purpose, the moving disc 14 is arranged on the side of the electric piston 13 facing away from the actuating pistons 10 so that its end is guided into the bore 16 of the block part 2. 15) may be rotatably mounted. The piston rod 15 is a pressure spring 17 which presses the electric piston 13 through the moving disc 14 to the left end position where the working pistons are in the starting position in the chamber 29 shown in FIG. surrounded.

In the cylinders 19 lying parallel to the axes of the actuating pistons, valve pistons 20 as two venting pistons are slidably mounted in the axial direction.

Each of these valve pistons has an annular groove 18 in the middle of its longitudinal direction which can be formed by rotary cutting or by using two collars 21. The outlet 22 is open into the cylinder 19 for the valve piston 20. When the valve piston 20 is in the open position (FIG. 1) this outlet connects to and communicates with the tube extension 8 of the vent pipe 7 via the cylinder 19 and the branch ducts 23, 4. . These branch ducts 23 begin to deviate perpendicularly from the tube extension 8 and are multi-branched so that the final branch 23a is connected to and communicates with the cylinder 19 of one of the valve pistons 20. (24) is open into.

At the end of the filling of the mold cavity (not shown) and before the liquid casting material reaches the tube extension 8 through the vent pipe 7, the actuating pistons 10 move the moving disc 14 and the electric piston 13. It is pressurized by the pressure spring 17 to the starting position shown in FIG. Once the casting material fills the extension 9 at the end of the tube extension 8, the casting material enters into the branch ducts 23. Since the total cross sectional area of the branch ducts starting from the tube extension 8 is substantially smaller than the cross sectional area of the tube extension 8 itself, the pressure in the extension 9 rises, so that the actuation pistons act on the spring. It is pressed against the end position shown in FIG. At the same time, the actuating pistons move the moving disc 14 and the electric piston 13 to the right of the figure, which moves the valve pistons 20 as shown in FIG. 2 due to a secure engagement in the groove 18. Move to position This causes the piston head 25 to move into the cylinder 19, which in turn disconnects the connection between the chamber 24 and the outlet 22. In this way, the outlet of the vent pipe is closed, while casting materials entering the chamber 24 through the branch ducts 23 are ejected out without passing through the outlet 22.

Due to the branching of the branch ducts 23 shown in FIG. 4, the ejection of metal or a small amount of metal injection, which may be before the dense metal flow, causes the metal flow to fill the extension 9 to vent the actuating pistons 10. The chamber 24 cannot be reached until the valve is moved to the end position shown in FIG.

The actuating pistons 10 and the valve pistons 20 are configured as plungers. The design of the valve piston is that the outer head face 26 (figure 5), which comes into contact with the casting material, in the terminal position shown by the dashed-dotted line in FIG. 5, is at least one third the diameter d of the piston head 25 The inner side of the cylinder wall in close contact with the piston by an axial distance T corresponding to four. As a result, thanks to this immersion depth, the walls at the end of the cylinder in contact with the hot casting material ensure that at least the piston head 25 receives as much heat as it receives through its head face 26 and, as a result, The increase in cylinder diameter due to heat is at least equal to the increase in the diameter of the piston head guided therein. This feature is also applicable to the heads of the actuating pistons 10.

For assembly reasons, the moving disc 14 is located in the chamber 29 of the block part 2 which is open towards the block part 1. The disc 14 is largely arc-shaped and is cut across the arc so as not to occupy the groove 18 at a position not occupying the groove 18. The edge of the moving disc has a flat portion 27. This flat is positioned such that the flat disc separates from the groove 18 on the valve piston at the angular position of the flat disc in the position shown by the dashed line in FIG. Thus, the disc 14 can be selectively rotated to a position that does not occupy the groove 18. As a result, in this angle (rotational) position, when the block parts 1 and 2 are separated from each other, the moving disc 14 together with the electric piston 13 and the piston rod 15, the groove 18, It may be moved out of the block part 2 past the collar 21 of the forming valve piston 20, and the valve piston may stay in the block part 2. In contrast, the valve piston can be withdrawn from the cylinder 19 without involving the moving disk 14, the electric piston 13 and the piston rod 15.

A pressure duct 28 connected from a pressure fluid source and capable of testing the operation of the vent valve before the casting operation is open into a cylindrical space 12 located between the actuating pistons 10 and the electric piston 13.

Claims (11)

A vent valve assembly for use in a die casting mold for venting a mold cavity, the vent valve assembly comprising: a block unit, a tube in a block unit configured to form an extension of the vent pipe of the die casting mold, a block unit tube, and in use It includes at least one valve piston mounted in the block unit for venting the vent and at least one actuating piston arranged in the block unit and exposed to the block unit tube to react to fluid pressure in the block unit tube against the reaction force generating means. And, in use, each valve piston of each of the actuating pistons so that a rise in fluid pressure in the block unit tube actuates each actuating piston and each valve piston so that each valve piston blocks the block unit tube and is not vented. Each valve piston on one side and the other on the other so as to move according to the movement Including a connecting portion located between each of the working piston, the axis of each of said valve piston and the working piston are each vent valve assembly, characterized in that it is virtually parallel. 2. A connector according to claim 1, wherein said connection between each valve piston on one side and each actuating piston on the other has a member occupying a space between two contact surfaces of each valve piston and one of each actuating piston. A vent valve assembly, characterized in that. The vent valve assembly according to claim 2, wherein said member is a disc. 4. The vent valve assembly according to claim 3, wherein the space occupied by the contact surfaces is a groove, and the member occupies the groove to enable radial play. 5. The vent valve assembly according to claim 2, 3 or 4, wherein the contact surfaces are respective valve pistons. 6. The vent valve assembly of claim 5, wherein a plurality of said actuation pistons all act on said member. 7. The vent valve assembly according to claim 6, wherein the electric piston is located between one actuating pistons and the other part of the member so as to transmit motion therebetween. 5. The vent valve assembly according to claim 1, wherein the reaction force generating means comprises a spring. 5. The vent valve assembly according to claim 4, wherein the disc can be selectively rotated to a position not occupying the groove. 10. The vent valve assembly of claim 9, wherein the disc is largely arc-shaped and is cut across the arc so as not to occupy the groove at the position. 5. The block unit according to claim 3 or 4, wherein the block unit is made up of two parts, and the disc has one block to contact the base of the chamber when each valve piston closes the block unit tube so that it is not vented. A vent valve assembly, wherein the vent valve assembly is located in a chamber within a unit part.