JPH1190606A - Vertical type die casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cast a casing having fine structure and high strength without micro-crack and micro-porosity, to surely execute the cutting-off of a feeder head and to attain the stable driving by reducing the hydraulic pressure at the head side of an injection cylinder when the stopping position of a pressurizing pin is higher than the scheduled stopping position to lower the output. SOLUTION: A pressure detector 41 detects that the hydraulic pressure of a pressurizing pin cylinder 22 detected with a pressurizing pin positional detecting device 3 becomes the max. value. When the pressurizing pin position is larger than the schedule value, a four-way valve 35 in a main circuit of the injection cylinder 9 is closed with the command from a control device 42, and a little quantity of oil is discharged from the hydraulic chamber 19 at the head side of the injection cylinder through a four-way valve 36 in an auxiliary circuit and the oil of the hydraulic chamber at the rod side is supplied and the pressurizing pin 21 is advanced to a prescribed position by pulling down a plunger 12 and a plunger tip 11 a little. After cooling and completing the solidification of the molten metal in die cavity and a round gate 27, the plunger tip 11 is drawn up and the feeder head is cut off by advancing the pressurizing pin 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical die casting method for injecting molten metal into a mold cavity from directly below.

[0002]

2. Description of the Related Art When a product made of an aluminum alloy is manufactured by casting, in the case of parts requiring strength, a vertical die casting machine is often used in order to prevent entrainment of gas during injection of molten metal. Regarding a method of manufacturing an aluminum wheel for automobiles, for example, as shown in Japanese Patent Publication No. 3-4297, a gate having a diameter smaller than the inner diameter of the injection sleeve and a pressure pin having a diameter slightly smaller than the inner diameter of the gate are placed upward. Casting that is provided so as to be able to freely move in and out of a movable mold toward a lower gate has already been used.

[0003]

SUMMARY OF THE INVENTION
No. 297, the gate diameter and the height of the basin above the gate are determined by the shaft hole of the wheel and the design of the wheel, and are not always sufficient for replenishing the molten metal necessary for solidification shrinkage. Was.

In order to ensure the strength of the cast product, it is necessary to sufficiently supply the molten metal necessary for solidification shrinkage. In the case of cast products other than aluminum wheels for passenger cars, the diameter of the circular gate and the size of the pool above the gate are required. There are few restrictions on the height and the like, and the required supply of molten metal can be sufficiently performed by appropriately selecting the diameter and stroke of the pressure pin.

[0005] However, when the molten metal is sufficiently replenished, the pin stops above the gate even when the accurate pin is pressurized at the maximum output. The stop position varies due to variations in hot water supply amount, hot water supply temperature, mold temperature and the like, and is not constant.

On the other hand, in order to separate the product and the feeder, the feeder (biscuit) must be cut at the circular gate by a pressurizing pin. It may happen that the output of the pin cannot be cut. In order to cut the riser with a pressure pin, the stop position of the pressure pin must be within a certain range.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has been designed at the time of designing an apparatus and a mold so that molten metal can be sufficiently replenished at the time of solidification shrinkage by an accurate pin. Select the pressure cylinder output, pressure pin diameter and stroke.

[0008] The molten metal is sufficiently replenished at the time of solidification and contraction by pressing the pressure pin, and even when the output of the pressure cylinder is maximized, the stop position of the pressure pin is affected by variations in the amount of hot water, the temperature of hot water, and the temperature of the mold. Is higher than the scheduled stop position, the position is detected, the signal is used to reduce the hydraulic pressure on the injection cylinder head side, reduce the output, and then pool the water.If the solidification of the gate is not completed, the pressure pin The plunger tip is retracted by the pressurization of the cylinder, the biscuit in the gate is pushed down, and the pressurizing pin moves forward to a predetermined position.

In this state, the casting is cooled in the mold. After cooling is completed, the plunger tip is retracted and the pressing pin is advanced again, so that the feeder is cut and separated by the pressing pin at the gate, and the product can be taken out after the mold is opened.

As described above, by completely and reliably replenishing the molten metal at the time of solidification shrinkage by pressurizing the pressure pin, it is possible to cast a stable and strong cast product without generating microcracks and microporosity in the cast product. At the same time, the feeder can be reliably separated and stable operation can be performed.

[0011]

The molten metal poured into the injection sleeve rises inside the injection sleeve by pushing up the injection plunger after docking the injection sleeve into the fixed mold, and after passing through the circular gate of the fixed mold, Filled into the mold cavity. The chill layer formed by cooling and solidifying on the inner surface of the injection sleeve is pushed up by the plunger and remains on the outer periphery of the entrance of the circular gate to increase resistance of the plunger advance.

When the solidification of the molten metal in the mold cavity progresses and contraction starts, it is necessary to pressurize with the injection plunger.
The injection plunger cannot move forward because the outer periphery of the feeder (biscuit) is solidified due to the accumulation of the chill layer. Therefore, the pressure in the hydraulic chamber on the head side of the injection cylinder increases. When this pressure rise is detected, the pressure pin is advanced into the basin to supply the molten metal to the mold cavity.

In order to make the structure of the cast product dense and to increase the strength, it is necessary to sufficiently supply the molten metal with the pressure pin, but the amount of the molten metal varies depending on the amount of hot water, the temperature of hot water or the temperature of the mold. It is. In particular, the difference in the amount of chill layer generated due to cooling and solidification on the inner wall of the injection sleeve causes a variation in the advance limit of the injection plunger, and the difference in the required amount of molten metal replenished by pressurization.

When the molten metal replenishment amount by the pressure pin is appropriate, when the maximum pressure is applied to the pressure cylinder, the pressure pin is cut to an appropriate dimension δ _{2 which} can be cut by the pressure pin shown in FIG. Move forward and stop. Thereafter, after the filled molten metal is cooled and solidified, the injection sleeve and the injection plunger are pulled back, and the pressure pin is advanced again to cut and separate the feeder at the circular gate as shown in FIG.

When a large amount of molten metal is required and the amount of molten metal supplied by the pressure pin is insufficient, the pressure resistance against the pressure pin is small and the pressure pin moves forward to the entrance of the circular gate as shown in FIG. Without replenishing the molten metal into the mold cavity, the feeder (biscuit) is simply pressurized and stopped. When the position becomes [delta] ₁ below shows the underfilled, requiring correction, such as stroke change of the pressure pin.

In the case where the inner surface of the injection sleeve is kept warm and the injection plunger advances a lot, or the solidification rate of the molten metal filled in the mold cavity is high and the amount of molten metal supplied by the pressure pin is small, the pressure pin may be used. At the high position δ ₃ as shown in FIG. In this case, when the molten metal is cooled and solidified, the pressure of the pressure pin is insufficient and the feeder (biscuit) cannot be sheared at the circular gate. it is advanced to [delta] ₂ is necessary to be able to cut and separated feeder even after cooling solidification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a vertical die casting method according to the present invention will be described in detail with reference to FIGS.

FIG. 1 shows a state in which the molten metal is poured into the injection sleeve at the position indicated by the two-dot chain line, and the injection device, which has been made vertical by a tilting cylinder (not shown), is in a state immediately before docking to the fixed mold. It is a longitudinal section of a machine. The mold clamping device is not shown since it is of a known type.

FIG. 2 is a longitudinal sectional view of the casting machine showing the state of docking, injection, and pressurization of the pressurizing pin in the upper mold. FIGS. 3 to 6 are operation sequence diagrams of the pressurizing pin, and FIGS.
FIG. 4 is a comparison diagram of a stop position of a pressure pin.

1 and 2, 1 is a horizontal fixed plate of a vertical die casting machine or a vertical squeeze casting machine, 2 is a movable plate that moves up and down in a horizontal state, 3 is a column, 3a is a column nut, and 4 is a column nut. A fixed die backup plate fixed to the fixed platen 1 is a fixed die as a lower die, and a movable die as an upper die.

Reference numeral 7 denotes an injection sleeve which can be attached to and detached from the fixed mold 5 at a lower central portion.
A docking frame 9 provided integrally with the injection cylinder 9, a docking cylinder 10 provided on an upper portion of the injection cylinder 9 for moving the injection sleeve 7 and the docking frame 8 up and down, and 11 slidable in the injection sleeve 7. , 12 is a plunger, 13 is a plunger joint, 14 is a piston and a piston rod of the injection cylinder 9, and the plunger 12 and the plunger tip 11 can be moved up and down by the vertical movement of the piston and the piston rod 14. .

The bottom of the injection cylinder 9 is rotatably mounted on an injection cylinder mounting plate 16 by a tilt shaft 15, and the injection sleeve 9 and the plunger tip are moved together with the injection cylinder 9 by the operation of a tilt device (not shown). 11 can be tilted to a position where hot water can be easily supplied by the ladle 17, as shown by a two-dot chain line in FIG. Reference numeral 18 denotes an injection cylinder mounting tie bar.

Reference numeral 25 denotes a casting hole provided at the lower central portion of the fixed mold 5, and the casting plunger 7 is docked with the upper end of the injection plunger 7 as described above. Casting port 25
Is the same as the inner diameter of the injection sleeve 7 and
5, the plunger tip 11 rises to a part of the inner surface.

A circular gate 27 which is smaller than the inner diameter of the injection sleeve 7 and communicates with the cavity 26 in the dies 5 and 6 is provided above the shaft core of the casting port 25. The upper end of the circular gate 27 has a relatively small diameter, and the lower side is slightly widened like a trumpet.

Reference numeral 21 denotes a pressurizing pin provided at the center of the movable mold 6 so as to be able to freely move in and out downward. Reference numeral 22 denotes a pressurizing pin cylinder, in which a cooling water passage 33 and a pipe are provided. 34 is provided so that the pressing pin 21 can be cooled from the inside.

Next, the operation of the vertical die casting method will be described.

After the mold is clamped, when the injection device is in a tilted state shown by a two-dot chain line in FIG.
4 is poured, and when the tilting is released, it becomes vertical as shown in FIG. 1, and then the docking cylinder four-way valve 39 is moved to the left as shown in FIG. And the injection sleeve 7 is a docking frame 8
And is docked to the fixed mold 5 by the docking cylinder 10.

Subsequently, the plunger tip 11 and the plunger 12 are raised by the action of the piston and the piston rod 14 of the injection cylinder 9 to fill the mold cavity 26 with the molten metal 24 and pressurize the plunger tip 11.

When the melt 24 is filled in the mold cavity 26 and the pressurization by the plunger tip 11 is started, the pressurization resistance increases. In particular, a chill layer 29 solidified in the injection sleeve 7 is deposited on the outer peripheral upper portion of the casting port 25, and is cooled from the fixed mold 5 so that it solidifies quickly, and the pressure resistance of the plunger tip 11 increases to advance. No longer.

When the plunger tip 11 stops, pressure oil is applied to the pressure pin cylinder 22 via the pressure pin cylinder four-way valve 40, and the pressure pin 21 is advanced at a high pressure, so that the solidification shrinkage volume in the mold cavity 26 is increased. Is filled with molten metal from the reservoir 28. In this case, the molten metal in the feeder (biscuit) 30 is almost solidified, the Pascal's principle does not work, and the plunger tip 11 does not retreat.

In order to reliably supply and fill the mold cavity 26, it is necessary to secure a sufficient supply volume of the pressure pin 21. The required replenishment volume changes, and the pressure stop position of the pressure pin 21 also differs.

This position is detected by the pressure pin position detection device 23. The pressure detection device 41 detects that the hydraulic pressure of the pressure pin cylinder 22 has become maximum, and the pressure pin position is larger than the predetermined value. In the case of δ ₃ in the state of above, after cooling, it becomes difficult to cut the feeder by the pressurizing pin 21.
, The four-way valve 35 of the main circuit of the injection cylinder 9 is closed, and a small amount of oil is discharged from the hydraulic chamber 19 on the head side of the injection cylinder by the four-way valve 36 of the auxiliary circuit.
Plunger 12 and plunger tip 1 by supplying 0 oil
When the pressure pin 1 is slightly lowered, the pressure pin 21 advances to a predetermined position. This state is shown in FIG.

Mold cavity 26 and circular gate 27
After the molten metal in the inside is cooled and solidified, the injection sleeve 7 and the plunger tip 11 are pulled down, the upper pressing pin 21 is advanced again, and the molded product in the mold cavity 26 and the feeder are moved to the minimum diameter portion of the circular gate 27. (Biscuit) 30 is cut off and the feeder 30 is pushed down. Then, the mold is opened and the molded product is taken out.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the molten metal is surely replenished and filled to the solidification shrinkage volume at the time of casting of a light alloy, and the plunger tip 11 is lowered and pressurized in an incompletely solidified soft state for overfilling. The pin 21 is advanced to a predetermined position so that the feeder can be reliably cut.

[0034]

As is apparent from the above description, in the present invention, the replenishment and filling of the molten metal with respect to the solidification shrinkage at the time of casting ensures that the structure has a dense structure free from microcracks and microporosity. In addition to being able to cast a strong cast product, the feeder was also reliably cut and stable operation was possible.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a casting machine showing an embodiment of an apparatus for carrying out a method of the present invention, showing a state immediately before an injection apparatus is docked to a fixed mold.

FIG. 2 is a longitudinal sectional view of a casting machine showing an embodiment of an apparatus for carrying out the method of the present invention, in which a mold is filled with a molten metal and a pressing pin is pressed.

FIG. 3 is an operation diagram when filling a mold cavity with a molten metal in FIG. 2;

FIG. 4 is an operation diagram of the completion of filling, which is a continuation of FIG. 3;

FIG. 5 is a continuation of FIG. 4 and is an operation diagram of pressure pin pressing.

6 is a continuation of FIG. 5, and is an operation diagram of feeder cutting. FIG.

FIG. 7 is an explanatory view showing a state of insufficient filling when a molten metal is filled in a mold cavity and pressed by a pressing pin.

FIG. 8 is an explanatory diagram showing a proper filling state when a molten metal is filled in a mold cavity and pressed by a pressing pin.

FIG. 9 is an explanatory diagram in a case where a molten metal is excessively filled in a mold cavity.

FIG. 10 is an explanatory view showing a pressed state of a plunger.

[Explanation of symbols]

 Reference Signs List 1 fixed plate 2 movable plate 3 tie 3a tie nut 4 fixed die backup plate 5 fixed die (lower die) 6 movable die (upper die) 7 injection sleeve 8 docking frame 9 injection cylinder 10 docking cylinder 11 plunger tip 12 Plunger 13 Coupling 14 Injection piston 15 Tilt axis 16 Injection platen 17 Laddle 18 Tie bar 19 Injection cylinder head side hydraulic chamber 20 Injection cylinder rod side hydraulic chamber 21 Pressure pin 22 Pressure pin cylinder 23 Pressure pin position detection device 24 Molten metal 25 Casting port 26 Mold cavity 27 Circular gate 28 Pool 29 Chill layer 30 Feeder (biscuit) 31 Plunger cooling water passage 32 Cooling pipe 33 Pressurized pin cooling water passage 34 Cooling pipe 35 Four-way valve for injection cylinder 36 Injection Auxiliary four-way valve for cylinder 37 Throttle valve 38 Flow control valve 39 Four-way valve for docking cylinder 40 Four-way valve for pressurized pin cylinder 41 Pressure detector 42 Controller

Claims (1)

[Claims] When a molded product is die-cast using an injection device provided below a lower fixed die, an upper movable die and a fixed die, a circular gate of a molten metal passage of the fixed die is formed. The diameter of the injection part is made smaller than the diameter of the injection sleeve, and the diameter of the insertion part is slightly smaller than the minimum diameter of the circular gate part of the molten metal passage. When filling the mold cavity with molten metal using a vertical injection device that can move up and down the circular gate, the majority of the oxide film on the surface of the molten metal in the injection sleeve is transferred to the inner surface of the injection sleeve. It prevents most of the generated cooling solidified layer from entering the mold cavity by leaving it in the feeder part, and when the molten metal in the mold cavity cools, it replenishes the voids caused by the solidification shrinkage of the molten metal. Make sure that the necessary and sufficient volume is If the tip of the pressurized pin stops at a size larger than expected above the entrance of the circular gate when pressurized with the maximum output of the pressurized pin cylinder, reduce the output of the injection cylinder and reduce the plunger tip To control the stop position of the tip of the pressure pin so that it falls within the expected range to cast a cast product with a dense structure and strong strength, and to secure the feeder part from the product by the pressure pin of the movable mold. Vertical die-casting method that can be cut and separated.