JPH0242021B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hard casting type die casting machine, in which an injection sleeve is inserted into the injection hole of the mold, and the molten metal in the injection sleeve is injected into the cavity of the mold. The present invention relates to a vertical injection device that injects into.

[Conventional technology]

Casting using a die-casting machine has traditionally been widely used as a method for manufacturing precision products in large quantities.In this type of casting, molten metal is filled into the cavity of a mold at high speed and high pressure. Since the gas may not escape sufficiently and may mix with molten metal and remain in the product as cavities, products for which void-free soundness is important are sometimes unsuitable.

In order to solve these inconveniences, the present applicant has proposed Utility Application No. 107265-1983 (Patent Application No. 13873-1987).
We have previously proposed a degassing device for molds that vents gas from the mold cavity during casting, eliminates gas entrainment, and produces healthy die-cast products.

This device is equipped with a gas vent valve in the gas exhaust path leading from the mold cavity to the outside of the mold, and when the valve is open, molten metal is injected into the cavity, and the gas with a small mass in the cavity is exhausted. When the molten metal has finished being discharged through the gas passage, the inertial force of the large mass of the molten metal that has entered the gas exhaust passage from inside the cavity is applied to the valve to close it, thereby blocking the outflow of the molten metal. Therefore, gas inside the mold can be reliably and easily vented.

The applicant has also developed a reduced-pressure or vacuum-type die-casting method and an apparatus therefor, in which the gas in the mold cavity is actively exhausted by connecting the gas exhaust path to a vacuum generator. This reduced pressure die casting method reduces the pressure by suctioning an amount of gas from the outside that is greater than the amount of gas that flows into the cavity from outside the mold through the gap, thereby eliminating gas from inside the mold. It can be made more reliable.

[Problem to be solved by the invention]

However, in such a conventional injection device, if injection is performed while the inside of the mold cavity is evacuated from above, air from the outside will be sucked in from the joint of the injection sleeve, so that the plunger tip will not open at the start of injection. The problem was that when the solidified layer formed at the tip broke during injection, air from the joint of the injection sleeve entered the molten metal and entered the mold cavity together with the molten metal.
That is, as shown in FIG. 8, which is a cross-sectional view of the injection sleeve insertion part, the fixed sleeve 5 is fitted into the injection hole 4 of the mold 3, which has the cavity 1 and the constriction part 2, and the injection sleeve 5 is fitted into the injection hole 4. For this purpose, an injection sleeve 7 to which molten metal 6 is supplied is inserted, and a plunger tip 8 is slidably inserted into the inner hole of the injection sleeve 7. At the start of injection, a solidified layer 9 is generated by solidifying the molten metal 6 on the molten metal contacting end surface of the plunger tip 8 and the inner surface of the injection sleeve 7 that is continuous with the molten metal contact end surface, and this solidified layer 9
is pushed up by the plunger 8 rising for injection, is compressed and crushed between the flat surface 10 in front of the constriction 2 and the end face of the plunger tip 8, and enters the fixed sleeve 5 without entering the cavity 1. , remains together with the biscuit, which is a solidified product of the molten metal 6, and is separated from the constriction 2 together with the biscuit when the product is taken out.

However, in the conventional injection device described above, when the gas in the cavity 1 is vacuum-suctioned, air flows out from the gap between the injection hole 4 of the mold 3 and the injection sleeve 7 inserted therein, as shown by the arrow in the figure. is sucked in, and this air enters between the inner surface of the fixed sleeve 7 and the coagulated layer 9, while the coagulated layer 9 is compressed by the plunger tip 8 and hits the flat surface 10, as shown by reference numeral 9A in the figure. When the solidified layer 9 is broken one after another, the air that has entered enters the molten metal between the broken solidified layer pieces 9A, passes through the molten metal, and enters the cavity 1 from the constriction 2. This air and the molten metal alternately pass through the constricted portion 2, which disturbs the flow of the molten metal, resulting in a drawback that a high-quality cast product cannot be obtained.

In addition, due to the suction caused by the reduced pressure inside the cavity,
The solidified layer 9 floats up from the end surface of the plunger tip 8, causing the injection sleeve 7 and the plunger tip 8 to
Another drawback was that the coagulated layer 9 was ruptured by the external air sucked through the gap between the coagulated layer and the coagulated layer and the air entered the cavity.

The present invention provides an injection device that solves these drawbacks.

[Means to solve the problem]

For this purpose, in the present invention, a vacuum suction device is provided to suck the gas in the mold cavity while the molten metal is supplied into the injection sleeve, and the fitting surface between the inserted injection sleeve and the injection hole An annular groove connected to a vacuum suction device was provided on the circumferential surface of each plunger tip.

[Effect]

With this configuration, air is sucked to the outside from the annular groove provided on the fitting surface of the injection hole and the injection sleeve and on the circumferential surface of the plunger tip.
Outside air is not sucked through the gap between the injection hole and the injection sleeve and between the injection sleeve and the plunger tip.

〔Example〕

1 to 7 show an embodiment of a vertical injection device for a die-casting machine according to the present invention, FIG. 1 is a schematic configuration diagram and a pneumatic piping diagram, and FIG. 2 is an enlarged cross-sectional view of an injection sleeve and a plunger. Figure 3 is a cross-sectional view taken along line A-A in Figure 2, Figure 4 is a cross-sectional view taken along line B-B in Figure 2, Figure 5 is a cross-sectional view taken along line C-C in Figure 2, and Figure 6 is a mold FIG. 7 is a longitudinal cross-sectional view of the degassing device, and is a cross-sectional view taken along line DD in FIG. 6. In these figures, a fixed mold 11 and a movable mold 12 are joined and clamped at a dividing surface 13, and a cavity 14, a constriction 15, and an injection hole 16 are formed inside the dividing surface 13. A fixing sleeve 17 formed in a semi-cylindrical shape is fitted into the injection hole 16. The die casting machine of this embodiment is of a horizontal mold clamping type and a vertical casting type, with a movable mold 1
The mold is clamped and opened by moving the mold 2 in the horizontal direction, and the injection cylinder 18 is disposed directly below the molds 11 and 12 as shown in FIG. The injection cylinder 18 is equipped with a piston rod 19 that moves forward and backward by hydraulic pressure, and a second piston rod 19 is provided at the working end of the piston rod 19.
Plunger 20, the details of which are shown in FIGS.
are concentrically connected via a coupling ring 21. Reference numeral 22 denotes an injection sleeve that is formed to have the same diameter as the fixed sleeve 17, and is moved up and down by a cylinder (not shown) and inserted into and removed from the fixed sleeve 17 at its tip end. And the inner hole 22a
The plunger tip 2 has 20 plunger heads.
3 is slidably inserted into the injection sleeve 2.
2 is removed from the fixed sleeve 17, and while the plunger tip 23 is inserted, the injection cylinder 18 and the injection cylinder 18 are tilted by a tilting cylinder (not shown) to inject the molten metal into the casting sleeve 22. After molten metal, the injection cylinder 18 is erected, the injection sleeve 22 is inserted into the fixed sleeve 17, and the piston rod 19 is advanced by hydraulic pressure, so that the plunger tip 23 injects the molten metal into the cavity 14.

Therefore, details of the plunger 20 will be explained. A plunger rod 24 connected to the piston rod 19 by a coupling ring 21 is connected to a screw hole 24 from above.
a, a pressure reducing pipe support hole 24b, an air passage hole 24c, and a bottom hole (not shown) are formed in this order.
The lower threaded portion 25a of No. 5 is screwed in as far as it will go until it stops at the stepped portion. A pair of upper and lower adapters 26 and 27 are loosely attached to the central threadless portion 25b of the threaded pipe 25, and an upper threaded portion 25c of the threaded pipe 25.
It is held between the plunger tip 23 and the plunger rod 24, which are screwed together. 28 is a holding cylinder (not shown) at the lower end and a pipe 28 welded thereto.
a, which is inserted from the bottom hole side (not shown) at the lower end of the plunger rod 24, and a holding cylinder is fitted into the upper end of the bottom hole,
The tube 28a passes through the air passage hole 4c and its upper portion is fitted into the pressure reducing tube support hole 24b. Reference numeral 29 is a water-cooled pipe held at the lower end of the plunger rod 24, passing through the pressure reducing pipe 28a and the threaded pipe 25, and having its tip connected to the space 23 of the plunger tip 23.
It is facing inside a. Reference numeral 30 indicates O-rings as sealing materials provided at various locations.

An annular groove 23b provided on the outer peripheral surface of the plunger tip 23 and an annular groove 26 provided on the upper surface of the adapter 26.
a is communicated with an air passage 23c, and an annular groove 27a provided on the lower surface of the adapter 27 is communicated with an air passage 27b provided with a filter 31 made of wire mesh. An air passage 32 formed between the air passage hole 24c of the plunger rod 24 and the pressure reducing pipe 28a and the annular groove 7a communicate with each other through an air passage 33, which is opened at the lower end of the air passage 32. For the suction hole that is not connected to the
5 is connected. On the other hand, the water cooling pipe 29
The lower end opening is connected to a cold water inlet (not shown) at the lower end of the plunger rod 24 via a cold water passage, an annular groove, etc., and the upper end opening is connected to the space 2.
3a, and the plunger rod 2 via a cold water passage 36 extending downward around the water cooling pipe 29, a water channel, etc.
4 is communicated with a cold water outlet (not shown) at the lower end. The cold water inlet is connected to a pump or the like by a flexible hose or the like, and the cold water supplied to the cold water inlet by the operation of the pump rises in the water cooling pipe 29 and fills the space 23a, and the plunger tip 23
After cooling, the water flows down the cold water passage 36 and is drained from the cold water outlet.

Next, the mold degassing device will be explained. On the outer periphery of the cavity 14 of both the molds 11 and 12,
A degassing path 40 and a degassing groove 41 communicating with this are formed on both sides of the dividing surface 13, and a mold degassing device, generally designated by the reference numeral 42, is located directly above the degassing groove 41. For example, the movable mold 12
Fixed on the side. That is, a cylinder 44 is attached to the upper end of the bracket 43 fixed to the movable mold 12, and the cylindrical spool 6 is attached to the lower end of the flange, which is the working end of the piston rod 45 that moves back and forth using the fluid pressure. Both molds 11,
It is fixed by being inserted into and removably inserted into a circular hole provided on the upper end surface of 12. When the mold is clamped or opened, the piston rod 4 is moved by the operation of the cylinder 44.
The spool 46 is configured to be inserted into and removed from the molds 11 and 12 via the molds 11 and 12. Mold 1
Below the spool 46 inserted into 1 and 12,
The valve chamber 47 is provided with a bypass 48 that detours laterally and communicates between the valve chamber 47 and the gas vent groove 41, and the lower end surface of the spool 46 is provided with a bypass 48 that detours laterally and communicates between the valve chamber 47 and the gas vent groove 41.
A valve seat 49 facing toward 7 is formed. Spool 4
Both rod portions 51a of a return rod 51 are slidably engaged with a pair of elongated holes 50 provided in the outer peripheral wall of the piston rod 6. A tension spring 52 is tensioned to bias the rod 51 upward. Below the return rod 51, a valve guide 53 is integrally formed with a cylindrical portion 53a and a pair of screw holes 53b.
is installed in the elongated hole 50 and fixed to the spool 46, and a valve rod 56 whose upper end threaded portion is screwed into the screw hole of the return rod 51 is slidably supported on the cylindrical portion 53a. ing. At the lower end of the valve stem 56 is a valve body 56 that seats on the valve seat 49 as it rises.
a is provided, and the valve 56a, which was open due to the gas pressure inside the cavity 14, is seated due to the inertia of the molten metal advancing at high speed from inside the cavity 14, and opens into the inner chamber of the spool 46 and the gas vent groove 41. , and the bypass 48. 7 is a ball that engages with the groove 56b of the valve stem 56 by the bias of the compression coil spring 58, 54 is a bolt, and 55 is a nut, which together form a locking mechanism. The valve body 56a, once closed by the pressure of the molten metal, is configured so that it will not open again due to the action of members such as the tension spring 52 unless an external force is applied. Note that the valve body 56a is opened by pushing down the rod portion 51a of the return rod 51. 59
is a stopper fixed to the bracket 43 that restricts the upper limit of the rise of the rod portion 51a of the return rod 51 which rises together with the spool 46 due to the operation of the cylinder 44. An exhaust hole 60 is opened at the lower end of the spool 6, and this exhaust hole 60 is connected to a pipe 61 of an air circuit (described later) shown in FIG.

The injection sleeve 22 into which the plunger tip 23 of the plunger 20 is slidably inserted is fitted into the injection holes 16 of 11 and 12 so that it can be inserted and removed, as described above, and its upper end is formed into a tapered shape. In addition, there is a space between the fitting upper end surface 22b and the injection sleeve abutting surface 17a of the fixed sleeve 17.
Packing material 17 as a sealing material formed into a half ring shape using heat-resistant materials such as copper and asbestos
b is interposed by being fixed to the fixed sleeve 17 side. Further, on the fitting surface between the injection sleeve 22 inserted into the injection hole 16 and the injection hole 16, annular grooves 11a and 12a are provided in half on the sides of the molds 11 and 12. An air passage 11b is communicated with the annular groove 11a on the mold 11 side and opened to the outside of the mold, and a pipe 75 shown in FIG.
is connected.

Next, the plunger 20 and the gas venting device 42
The pneumatic circuit will be explained based on FIG. The pipe 63 connected to the vacuum pump 62 is connected to the pipe 6 on the way.
4 and piping 65, and piping 63, 6
4, there is a vacuum tank 66 and an auxiliary vacuum tank 67.
and piping 63,
64 is connected to the pipe 3 via filters 68 and 69.
1 and 35, respectively. Solenoid valves 70 and 71 are disposed on the pipes 64 and 65, respectively. When the solenoid of the solenoid valve 70 is excited from the state shown in the figure, the air in the plunger 20 is sucked, and the solenoid of the solenoid valve 71 is When excited, the cavity 1 is energized through the gas venting device 42.
The air inside 4 is sucked. In this case, the suction on the degassing device 42 side is set to be delayed by about 0.2 seconds to 1 second, preferably about 0.3 to 0.5 seconds, relative to the suction on the plunger 20 side, according to a command from a timing control device (not shown). . Further, the degree of vacuum is set to, for example, 200 to 300 Torr on the plunger 20 side and 150 to 250 Torr on the gas venting device 42 side.
This is achieved by providing an auxiliary vacuum tank 67. The auxiliary vacuum tank 67 is provided as close as possible to the plunger 20 in consideration of resistance generated in relatively thin piping sections and passages during vacuum suction. Further, the pipe 35 having the flexible hose 34 is made as short as possible and has a relatively large pipe diameter, for example, 1 inch.

Furthermore, the air passage 1 provided in the fixed mold 11
A pipe 75 including a filter 72, a flexible part 73, and a solenoid valve 74 is connected to 1b, and this pipe 75 is connected to the auxiliary vacuum tank 67.
Solenoid valve 70 of piping 35 heading from to plunger 20
is connected in front of.

Furthermore, the other port of the solenoid valves 70, 71, 74 has a piping 8 equipped with solenoid valves 78, 79, 80.
1, 82, and 83 are connected to each other, and these pipes 81, 82, and 83 are joined to a pipe 85 provided with a variable throttle valve 84, and connected to, for example, an air compressor 86 in a factory. And solenoid valve 7
Close solenoid valves 78, 79, 80 by closing valves 0, 71, and 74.
By opening, high-pressure air is sent to the plunger 20, injection sleeve 22, and degassing device 42, and is used for spraying for internal cleaning.

Next, a casting method using the die casting machine configured as above will be explained. The movable mold 12 is moved to the illustrated position and clamped, and the cylinder 44 of the degassing device 42 is operated to engage the spool 46 into the spool holes of the molds 11 and 12 as illustrated. At this time, the piston rod 19 of the injection cylinder 18 and the injection sleeve 22 are lowered, so the injection cylinder 18 is tilted to inject the molten metal into the injection sleeve 22 where the plunger 0 is lowered, and then raised again. Raise the injection sleeve 22 and remove the fixed sleeve 17 as shown in the figure.
engage with. After evacuating, which will be described later, oil is supplied to the injection cylinder 18 and the piston rod 19 is raised, the plunger 20 is raised and injection of the molten metal, indicated by reference numeral 87 in FIG. 2, is started. At this time, cold water is being supplied to the plunger 20 from the cold water inlet, and this cold water rises in the water cooling pipe 29, overflows into the space 23a, and flows down in the cold water passage 36, so that the plunger tip 23 and Plunger rod 24 is cooled. Furthermore, the injection sleeve 22 is also cooled from the outside by a cooling device (not shown). Therefore, on the upper end surface of the plunger tip 23 and on the inner wall surface of the injection sleeve 22 following this, a solidified layer is formed by the solidification of the molten metal, as indicated by the reference numeral 9 in FIG. 2 and FIG. 8. On the other hand, the vacuum tank 66 and the auxiliary tank 67 have been previously depressurized by suction with the vacuum pump 62, so when the solenoid valve 70 is first opened before or during injection, negative pressure is applied to the suction hole of the plunger rod 24. acts, and the air in the annular groove 23b of the plunger tip 23 is sucked through the air passage 23c, the annular groove 26a, the filter 31, the air passage 27b, the annular groove 27a, the air passage 33, and the air passage 32. Furthermore, when the solenoid valve 70 is opened and the solenoid valve 74 is opened at the same time, negative pressure acts on the air passage 11b communicating with the annular grooves 11a and 12a, and the air in the annular grooves 11a and 12a is sucked through the air passage 11b. be done. Furthermore, when the solenoid valve 71 is opened about 0.2 seconds to 1 second later, preferably 0.3 seconds to 0.5 seconds later, the cavity 14
The gas inside the cavity 14 is sucked through the exhaust hole 60 through the gas vent path 40, the gas vent groove 41, and the bypass 48, and the gas inside the cavity 14 is discharged. By suctioning from both the plunger 20 side and the gas venting device 42 side in this way, the vacuum level inside the cavity 14 and the gap between the injection sleeve 22 and the plunger tip 23 will be the same, but the plunger By suctioning the side slightly faster and by making the degree of vacuum on the plunger 20 side larger than the degree of vacuum on the degassing device 42 side, the coagulated layer 9 is formed on the end surface of the plunger tip 23 and its side, as shown in FIG. It is strengthened by adhering to the surrounding annular recess, and as the plunger tip 23 cools, it
The solidified layer 9 becomes thicker by cooling to ~400°C. As a result, infiltration of outside air through the gap between the injection sleeve 22 and the plunger tip 23 is blocked as much as possible. Moreover, the molten metal does not get inserted into the cavity 14 before the molten metal is injected.

After creating a vacuum inside the cavity 14 in this way, the injection operation begins, and when the plunger tip 23 is advanced while degassing, the molten metal 87 in the injection sleeve 22 is transferred to the fixed sleeve 17.
The liquid is injected into the cavity 14 through the constriction part 15. As the plunger tip 23 moves forward, the coagulated layer 9 is pushed upward by the plunger tip 23, and the upper end of the coagulated layer 9 reaches the plane 1 in front of the constriction 15.
1c, 12c, but the annular grooves 11a, 12
Since the air is sucked from a and 23b, outside air does not enter the cylindrical portion of the solidified layer 9, and the solidified layer 9 rises together with the plunger tip 23 while remaining in close contact with the inner peripheral surface of the injection sleeve 2. Its tip is a plane 11c, 1 in front of the constriction part 15
2c. And plunger tip 23
As the solidified layer 9 further rises, the solidified layer 9 forms the end face of the plunger tip 23 and the flat surface 1 of the molds 11 and 12.
1c and 12c, the solidified layer 9 is broken, but even if the inside of the cavity 14 is evacuated from above, air will not enter from the injection sleeve as described above, so no air will enter the molten metal. It does not get in and does not disturb the flow of the molten metal. When the cavity 14 is filled with the molten metal 87, the molten metal 87 rises in the gas vent groove 41 and comes into contact with the lower surface of the valve body 56a together with the gas. At this time, the valve body 5
The impact applied to the gas valve element 56a is larger than the impact applied to the gas valve element 56a, since the impact applied to the gas valve element 56a is extremely large compared to the mass of the gas of the molten metal 87 and has a large inertia.
6a moves upward while compressing the compression coil spring 58 with the ball 57, and the valve body 56a closes the valve seat 49. The molten metal 87 is then blocked from flowing out from the valve seat 49 and mixes with the gas in the gas vent path 40 and gas vent groove 41, forming droplets and discontinuously hitting the valve body 56.
Even in case a, the valve body 56a that has been pushed up by the molten metal 87 is pulled upward by the tension spring 52, so that the upper position is maintained and the exhaust passage is reliably closed by the valve body 56a.

After pressurizing and cooling for a predetermined time with the valve body 56a closed, the movable mold 12 is opened, and the spool 46 is raised by the cylinder 44 of the degassing device 42 to disengage from the movable mold 12. Take out the product.

Note that when the spool 46 is raised, the valve body 56
Due to the separation resistance between a and the solidified metal, only the spool 46 rises and the valve stem 56 rises with a delay.As a result, the ball 57 that had come off from the groove 56b of the valve stem 56 engages with the groove 56b again, and the next time Preparation for casting will be completed. Furthermore, at the upper limit of the spool 46, the return rod 51 contacts the stopper 59 and pushes down the valve rod 56, so that the valve body 56a is reliably opened and ready for the next casting.

By the way, normal aluminum products are 40 to 60
It contains gas of cc/100gAl, but when using the degassing device 42, the gas becomes 5~10c.c./100gAl, and a high quality product with pressure resistance of 100~150Kg/ ^cm2 can be obtained. Generally, heat treatment is possible when the gas content is less than 5 c.c./100 g Al, and welding is possible when the gas content is 1 c.c./100 g Al. This results in an injection product that can be heat treated and welded. In addition, this can be achieved not only by using new materials but also by using return materials.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a vertical injection device for a die-casting machine is provided with a vacuum suction device that sucks gas in the mold cavity while molten metal is being supplied into the injection sleeve, and On the fitting surface between the inserted injection sleeve and the injection hole and on the circumferential surface of the plunger tip,
An annular groove connected to a vacuum suction device is provided to vent gas inside the mold cavity, and vacuum suction is also carried out from both the inside and outside of the injection sleeve, facilitating degassing and producing high-quality products. At the same time, even if a solidified layer of molten metal is generated on the molten metal contacting end surface of the plunger tip and pushed up by the rise of the plunger, air will not leak out from between the injection hole and the injection sleeve and between the injection sleeve and the plunger tip. Since outside air is not sucked in and enters from outside, no cavities or pinholes will occur in the cast product, and the casting surface will be good, resulting in a significant improvement in the quality of the cast product.

[Brief explanation of drawings]

1 to 7 show an embodiment of a vertical injection device for a die-casting machine according to the present invention, FIG. 1 is a schematic configuration diagram and a pneumatic piping diagram, and FIG. 2 is an enlarged sectional view of an injection sleeve and plunger. , Figure 3 is the second
FIG. 4 is a sectional view taken along line BB in FIG. 2, FIG. 5 is a sectional view taken along line C-C in FIG. Figure 7 is D of Figure 6.
-D sectional view, FIG. 8 is a sectional view of an injection sleeve insertion portion of a conventional injection device. 11... fixed mold, 11a, 12a... annular groove, 11b... air passage, 12... movable mold, 1
4...Cavity, 16...Injection hole, 18...
Injection cylinder, 22... Injection sleeve, 23b...
...Annular groove, 42...Mold gas venting device, 62...
Vacuum pump, 66... Vacuum tank, 67... Auxiliary vacuum tank, 70, 71... Solenoid valve, 74... Solenoid valve, 75... Piping, 87... Molten metal.

Claims (1)

[Claims] 1 Vertical injection of a die-casting machine in which the injection sleeve 22 on the side of the injection cylinder 18 is inserted into and removed from the injection hole 16 at the lower end of the molds 11 and 12, and the molten metal 87 inside the injection sleeve 22 is injected into the mold cavity 14. The apparatus includes a vacuum suction device that sucks and exhausts the gas in the mold cavity 14 while the molten metal 87 in the injection sleeve 22 is being supplied, and also
A vertical injection device for a die-casting machine, characterized in that annular grooves 11a, 12a, and 23b connected to the vacuum suction device are formed on the fitting surface of the injection hole portion 16 and the circumferential surface of the plunger tip 23, respectively. .