JPS599263B2 - Die casting method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in vertical die casting methods and apparatus.

In the conventional general die casting method and apparatus, the mating surfaces of two molds are arranged vertically, and the shot cylinder for casting molten metal, that is, molten metal, into the cavity of the mold is arranged horizontally.

In such an apparatus, the molten metal injected into the shot cylinder is placed in a long and spreading state at the bottom of the inner wall of the shot cylinder.

However, foreign substances such as metal oxides and non-metallic compounds float on the surface of the molten metal, and when the plunger advances inside the cylinder, the air inside the cylinder is drawn in, so high-speed, high-pressure injection is required.

Furthermore, there is a possibility that the above-mentioned foreign substances may also be mixed into the molten metal.

These air bubbles and foreign substances gather above the molten metal in the shot cylinder and are injected into the cavity together with the molten metal through the runner and solidified.

Therefore, the strength of the material of the cast product was poor and a high quality product could not be obtained.

Furthermore, since the foreign matter has a higher consistency than the molten metal, it remains in the details of the cavity and obstructs the flow of the molten metal, causing casting wrinkles and turtle lines on the surface of the product and causing molding defects.

In addition, the molten metal that spreads inside the cylinder cools quickly, and in alloys with high melting points such as iron-based or copper-based alloys,
If the problem is severe enough to cause poor molten metal circulation in the cavity or the formation of cavities, molding will become impossible.

For these reasons, it has been proposed to use an inclined injection cylinder or vertical die casting.

However, in the former method, the connection port of the shot cylinder to the mold is located relatively downward in order to prevent the molten metal from flowing into the mold cavity when the molten metal is injected into the shot cylinder.

For this reason, the flow of hot water into the upper part of the cavity was poor, and large molds could not be used.

In addition, although the core water injected into the cylinder is better than that of the horizontal type, it is still quite spread out, so it cools quickly and the heat distribution in the cylinder is not uniform. There were problems when casting high melting point metals.

Furthermore, it is necessary to level the device when installing and removing the mold, which has the disadvantage of making the device complicated and increasing costs.

An example of the latter vertical type is U.S. Pat. It must be extracted from the cylinder.

This increases the distance the piston moves and increases cycle time.

Furthermore, the long movement distance of the piston is particularly disadvantageous for casting high-melting point metals, since it takes time for the molten metal to cool down after the pouring is completed and until the injection is completed.

In order to smoothly insert the extracted piston into the shot cylinder, the movement accuracy of the piston must be high, making the mechanism complicated.

Furthermore, since the upper mold was a movable mold, the mold clamping mechanism was located at the top, making it difficult to automatically supply hot water during pouring.

Furthermore, since the spout is located at the upper end of the shot cylinder, the distance from the spout to the bottom surface is long, which has the drawback of increasing thermal shock and shortening the service life, especially for high-melting point metals.

The present invention eliminates such drawbacks, and its purpose is to reduce the area of the core metal that comes into contact with air when the molten metal is poured into the shot cylinder, thereby improving the heat retention of the molten metal and improving the casting of high-melting point metals. It is an object of the present invention to provide a die-casting method and apparatus which can level the molten metal and collect foreign matter in the molten metal upward to prevent it from entering the cavity.

Another object of the present invention is to make it possible to provide the connection between the shot cylinder and the mold at any position, to improve the flow of hot water into the mold cavity, and to prevent the molten metal from flowing when the shot cylinder is inlet. To provide a die-casting method and device in which a lower plunger receiving molten metal is placed upward at the beginning of pouring and then moved downward as the molten metal is poured, thereby mitigating thermal shock between the shot cylinder and the lower plunger and extending their life.

Furthermore, another object of the present invention is to shorten the travel distance of the upper plunger that pumps the molten metal in the shot cylinder to the mold cavity, thereby shortening the casting cycle time and increasing productivity. It is an object of the present invention to provide a die-casting method and device which has a simple mechanism and low cost by inserting the die-casting device into a cylinder.

Still another object of the present invention is to provide a die casting method and apparatus that facilitates automatic supply of molten metal by providing a mold clamping mechanism in the lower mold.

Other objects of the invention will become apparent from the detailed description provided below.

The detailed structure of the present invention will be explained below with reference to FIG. 1, which is an embodiment.

FIG. 1 is a longitudinal sectional view showing that the fixed die plate 1-11 is attached directly to a machine frame (not shown) or is attached by a quiver or the like to fix the upper mold 12.

A movable die plate 13 is moved a predetermined distance in the vertical direction by an existing mold clamping mechanism (not shown) such as a toggle or direct pressure type, and fixes the lower mold 15 via a block 14.

Thus, both molds 12 and 15 form a cavity 16 and a runner 1γ when they are closed.

A sleeve 18 is inserted approximately in the center of the upper mold 12, and an intermediate sleeve 20 and an upper end sleeve 21 are inserted into the fixed die plate 11 through a support cylinder 19 so as to have the same inner diameter and coaxiality as the sleeve 18. There is.

Note that the sleeve 18, intermediate sleeve 20, and upper end sleeve 21 will be collectively referred to as the shot cylinder 22 hereinafter.

The shot cylinder 22 is fixed to the fixed die plate 11 and the upper mold 12 by a lid 23 at the upper end, and has an upper plunger 24 inside thereof that slides in the vertical direction.

Since the two flangers 24 are configured to remain within the shot cylinder 22 even when in the highest position, they are connected to a hydraulic cylinder (not shown) which is a driving source by a simple joint.

Describing the details of the structure of the shot cylinder 22, the upper end sleeve 21 simply guides the upper plunger 24, and since no internal pressure is applied by the molten metal during injection, almost no mechanical strength is required.

However, as shown in the figure, the shot cylinder 22 has an angle of 30° to 150° with respect to the axis, and is kept warm by the heating wire 26, and has poor wettability with the molten metal to prevent adhesion of the molten metal and to retain the heat, resulting in low thermal conductivity. It is made of a surface-treated material such as small ceramics or its coating, and is equipped with a hopper-shaped pouring port 25 with an opening to the upper end sleeve 21 near the lower end of the upper end sleeve 21, so that it comes into contact with the molten metal during pouring. .

Therefore, the upper end sleeve 21 is made of a material that has less reactivity with the molten metal to prevent the molten metal from adhering to it, and is also made of a material with excellent wear resistance or a material that has been surface-treated such as a coating to meet the purpose. There is.

Specifically, they are ceramics such as ZrB2, BN, Sl3N4, TIB2 and their coatings, or refractory and heat-resistant metals subjected to surface treatments such as nitriding and boriding.

Since the maximum injection amount of Mitoyu is at the position indicated by A in the figure, that is, near the boundary between the upper end sleeve 21 and the intermediate sleeve 20, internal pressure acts on the intermediate sleeve 20 during injection, but in this case the internal pressure is within the cavity 16. Similar to the upper end sleeve 21, high mechanical strength is not required since only a relatively low pressure is generated due to the flow resistance for filling the sleeve with molten metal.

Therefore, the middle sleeve 20 is made of a material that has low thermal conductivity, wear resistance, and poor wettability with drunken water, and the upper end sleeve 21
Manufactured from almost the same material.

The sleeve 18 is the part with the most severe conditions, and the characteristics required for it are, like the intermediate sleeve 20 and upper end sleeve 21 described above, excellent wear resistance, little reaction with molten metal, and low thermal conductivity for heat retention. Good sexuality is desired.

In addition, after the cavity 16 is filled with rock hot water, a higher pressure is applied to the rock hot water than during injection in order to obtain a high-quality die-cast product, so mechanical strength is also required.

For these reasons, the material of the sleeve 18 is a heat-resistant and refractory metal that has been surface-treated.
Hot work tool steels such as typified by , Ni-based superalloys such as Hastelloy, Inconel and Nimonik, and carbon steels such as HS-25.
O-based superalloys, W-based superalloys known as Ambiloy, refractory superalloys such as TM, which is a T+Mo alloy, and TZM with Zr added thereto, as well as nitrided or borated materials are used. .

A plurality of air vent grooves 42 are provided along the axial direction on the inner peripheries of the upper end sleeve 21 and the lid 23 to prevent hot water from blowing back during pouring.

Further, a mold coating material injection mechanism 43 is communicated with this air vent groove 42, and is connected to the inner surface of the shot cylinder 22 and the upper plunger 2.
A coating agent is applied to the tip of the plunger 4 and the insert 33 at the tip of the lower plunger 29, which will be described later.

On the other hand, a lower sleeve 27 is inserted into the lower mold 15 so as to have the same inner diameter and the same axis as the shot cylinder 22, and is fixed with a lid 28.

Inside the lower sleeve 27 and the shot cylinder 22 is a lower plunger 29 that faces the upper plunger 24 and moves up and down.
is inserted, and the lower plunger 29 is connected to the cylinder 30.
It is connected to the inner piston 31 via a piston rod 32, and there is a insert 3 on the top surface that can be replaced in a relatively short time.
3 is secured by screws or other attachment mechanisms.

As can be imagined from the fact that the shot cylinder part directly below the sprue is most severely eroded in general horizontal die-casting machines, the insert 33 is the part where the molten metal falls, and when pouring, the lower plunger 29 is moved to the shot cylinder 22. Although the falling energy of the fermented water is minimized by raising the temperature to near the pouring port 25, this is the part that is most severely eroded by the molten metal.

For this reason, Jinko 33 is made of heat-resistant metals, graphite, ceramics, or materials coated with these materials, which have low thermal conductivity and are resistant to the thermal shock of hot water.
9 from erosion of hot water.

Further, a groove 34 is provided on the outer peripheral surface of the lower plunger 29,
The same groove 34 is used for the lower plunger 29 and the piston rod 32.
It is connected to a coating agent injection mechanism 36 through a hole 35, so that a coating agent is applied to the inner surface of the lower sleeve 27 and the shot cylinder 22 when necessary.

Further, a spring 37 is provided between the lower surface of the piston 31 and the bottom surface of the cylinder 30.

The lower surface of the cylinder 30 is in contact with the extrusion piston 38,
After pressing the molten metal into the cavity 16, when the product solidifies and cools, the extrusion piston 38 is raised and the lid 3 of the hydraulic cylinder 30 is moved.
The product in the lower mold 15 is extruded by an extrusion rod 40 attached to the mold 9.

Further, the cavity 16 is connected to a pressure reducing mechanism (not shown) through a hole 45 in the upper mold, and the pressure is reduced before pouring the metal into the cavity 16 to prevent air from being entrained.

Packings 44 and 41 are attached to the outer peripheral surfaces of the upper mold 12 and lower mold 15 and to the sliding parts of the lid 28 and the piston rod 32 in order to enhance the effect during pressure reduction.

Next, the operation of the present invention will be explained with reference to FIGS. 1 to 7.

Figure 1 shows that after the product in the cavity 16 has solidified and is ejected by the extrusion rod 40, the surface of the cavity 16 of the lower molds 12 and 15 is cleaned with high pressure air to protect the surface of the cavity 16 and facilitate product removal. In order to achieve
After spraying or flame centering on the runner 17, and setting the core if there is one, the upper mold 15 is raised by the mold clamping mechanism, and mold clamping is completed.

Along with the coating of the cavity 16 and runner 17, the coating agent injection mechanism 43 also coats the tip surface of the first plunger 24, the inner surface of the upper end sleeve 21 of the shot cylinder 22, and the upper surface of the insert 33 at the tip of the lower plunger 29. .

The lower plunger 29 is then driven by the hydraulic cylinder 30 to move upward.

During this upward movement, the coating agent is sent from the coating agent injection mechanism 36 to the groove 34 on the outer peripheral surface of the lower plunger 29 through the hole 35, and the coating agent is applied to the inner surfaces of the sleeve 18 and the intermediate sleeve 20 of the shot cylinder 22 to form a relatively thick layer. applied to the eyes.

As the mold coating agent, a somewhat hard paste-like material whose main component is a refractory material such as graphite, asbestos, or ceramics is used.

In this way, the lower plunger 29 rises while coating the inner surface of the shot cylinder 22, and stops when the groove 34 of the lower plunger 29 comes to a position slightly above approximately position A, as shown in FIG. This is called the first position.

The lower plunger 29 descends immediately after stopping as described above, and stops again when the upper surface of the insert 33 coincides with line A as shown in FIG. 3. This position is called the second position, and at this point pouring Preparations are complete.

Immediately thereafter, molten metal is poured from the opening of the pouring spout 25 by hand or by an automatic hot water supply mechanism, as shown in FIG.

The lower plunger 29 descends simultaneously with the injection of the molten metal.

The descending speed at this time is determined by the speed of the lower plunger 29 so that the molten metal level in the shot 1 cylinder 22 is always near line A as shown in FIG.

By selecting the descending speed of the lower plunger 29 in this manner, it is possible to minimize the erosion of the inner surface of the insert 33 and the shot 1 cylinder 22 by the molten metal.

Furthermore, by synchronizing the amount of molten metal injected and the descending speed of the lower plunger 29, the entire surface of the molten metal inside the shot cylinder 22 has less ripples and the falling energy of the molten metal is lower.
In order to prevent shock heating of the intermediate sleeve 20 and the sleeve 18, which has particularly severe conditions, and to make the temperature distribution uniform in the circumferential direction, the shot 1 and the cylinder 2 are
This will improve the lifespan of 2.

When the pouring operation is finished, the lower plunger 29 is immediately moved to the position shown in FIG.
descend to a position opposite to.

At this point, the cylinder 3 which is the driving source of the lower plunger 29
The hydraulic circuit No. 0 is opened, and the lower plunger 29 is stopped at the position shown in FIG. 5 by the spring 37.

Note that this position is referred to as the third position. The cavity 16 and the runner 17 are closed by a lower plunger 29, and when the hot water is stored in the shot cylinder 22, the cavity 16 is connected to a vacuum chamber through the hole 45 of the upper mold 12 and is depressurized. Ru.

In this case, there is a packing 44 on the external joint surface of the upper mold 12 and the lower mold 15, and the upper surface of the lower plunger 29 in contact with the runner 17 is sealed with bamboo hot water, and the lower surface is provided with a packing 41 for the piston rod 32. Therefore, the pressure in the cavity 16 and runner 17 can be effectively reduced without requiring a large vacuum chamber.

Further, the supply of mold coating agent from the groove 34 of the lower plunger 29 ends at this point and is not continued until the next cycle.

As soon as the lower plunger 29 remains in the position shown in FIG.
Detecting means such as a change in oil pressure causes the upper plunger 24 to descend and apply pressure to the molten metal in the shot cylinder 22.

This action causes the spring 37 supporting the lower plunger 29 to bend, and as a result, the lower plunger 29 further descends and lands on the lid 28, as shown in FIG. 6, and this position is referred to as the fourth position.

At this position, the shot cylinder 22 communicates with the cavity 16 via the runner 17, so that hot water flows into the cavity 16.

When the cavity 16 is filled with molten metal, the pressure of the molten metal increases rapidly, so it can be detected from the change in the oil pressure of the hydraulic cylinder that drives the upper plunger 24, or from the pressure of the upper plunger 24.
The hydraulic circuit of the hydraulic cylinder for driving the upper plunger 24 is switched to high pressure by means such as detecting through a position detection mechanism such as a limit switch that the water passes through a preset position, and the pressure of the hot water is increased to increase the pressure of the product. increase the density of

After this state is maintained for a certain period of time and the hot water is completely solidified, the movable goo plate 13, lower mold 15, and extrusion piston 38 are lowered by the mold clamping mechanism as shown in FIG.

Next, the movable goo plate 13 is held at that position, and the extrusion piston 38 is raised, and the extrusion rod 40 is moved through the cylinder 30.
The product 51 is extruded from the lower mold 15 by the lower plunger 29.

In addition, in the above embodiment, the shot cylinder 22 is connected to the upper mold 1.
Although the arrangement is shown in the central part of 2, the arrangement is not limited to this and it is possible to arrange it at any position.

As explained above, in the die casting method and apparatus according to the present invention, the mating surfaces of the upper and lower molds are horizontal and the shot cylinder is arranged perpendicularly to both molds, so that the molten metal can be shot in one shot.
・When poured into the cylinder, the molten metal has a small surface that comes into contact with air, so it has high heat retention and is particularly advantageous for casting high-melting point metals.Also, foreign matter in the molten metal collects in the upper part of the shot cylinder and is difficult to mix with the cracks. So you can get good quality products.

In addition, by arranging both molds and the shot cylinder as described above, it is possible to connect the shot cylinder to any part of the mold, which improves the flow of hot water to the mold tip, and also improves the flow of hot water into large molds. enabled the use of

In addition, in the present invention, when the molten metal flows out, the lower plunger first receives the molten metal at an upper position, so the thermal shock caused by the falling energy of the lower plunger is reduced, and the descending speed of the lower plunger is synchronized with the large amount of molten metal. By reducing the ripple and falling energy of the double hot water, it prevents shocking heating from being applied to the shot cylinder, making the temperature distribution uniform and extending its life.

Furthermore, the upper plunger is always inside the shot cylinder,
In addition, since the pouring port is provided above the shot cylinder, the stroke of the upper plunger is short, reducing cycle time and increasing productivity, and the mechanism for moving the upper plunger can be simplified.

In addition, since the mold clamping mechanism of the present invention is provided in the lower mold, a blank space is left in the upper part of the upper mold, which facilitates the pouring of core hot water and enables installation of a simple automatic hot water supply mechanism. It has advantages.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIGS.
The figures are cross-sectional views illustrating the operation of the present invention in order. 11...Fixed guide plate, 12...
Upper mold, 13...Moving guide plate, 15...
...Shimogane, 16...Kisebitei, 17...
...Runner, 18...Sleeve, 20...
...Middle sleeve, 21 ... Upper end sleeve, 22 ... Shot cylinder, 24 ...
How many flangers, 25... Pouring spout, 27...
... lower sleeve, 29 ... lower plunger,
32... Piss 1 ~ Nrod, 33...
Insert, 34...Groove, 36...Second coating mechanism, 42...Air vent groove, 43...
First coating mechanism.

Claims (1)

[Scope of Claims] 1. While the lower plunger in the shot cylinder is rising to the first position, a groove provided on the outer circumferential surface of the lower plunger is connected to a coating material injection mechanism, whereby the coating material is injected from the groove into the shot cylinder. The molten metal is applied to the inner surface, and when it descends from the first position to a second position located at a fixed distance, the molten metal is poured into the shot cylinder from above a hopper-shaped pouring port that opens near the upper part of the second position in the middle of the shot cylinder and has a heat retention function. and lower the lower plunger in synchronization with the injection amount of the molten metal so that the upper surface of the molten metal remains at a substantially constant position, and when the predetermined amount of molten metal is completed, the side surface of the lower plunger communicates with the cavity. The upper plunger is then lowered to apply pressure to the core bath, and the lower plunger is lowered to the lowest fourth position by the same pressure. A die casting method characterized in that a runner is brought into communication with the molten metal and the molten metal is fed into a cavity. 2. An upper mold that is fixed to a fixed gouging plate and has a horizontal dividing surface, a shot cylinder that is vertically attached to the upper mold, and an upper plunger that slides up and down within the shot cylinder and is always located within the shot cylinder. and,
A lower mold that is fixed to a movable die plate and moves vertically; a lower sleeve that is vertically attached to the lower mold and coaxial with and has the same inner diameter as the shot cylinder; and a lower sleeve that moves vertically within the lower sleeve and within the shot cylinder. In a die casting device having a sliding lower plunger, the shot cylinder is fixed to the middle of the shot cylinder at an angle of 30° to 150° with respect to the axis, and has a surface treatment such as ceramics or a coating thereof to prevent the adhesion of hot water. a hopper-shaped pouring spout having a heating mechanism; a groove provided on the outer circumferential surface of the lower plunger and connected to the coating material pouring mechanism;
After raising the lower plunger to the second position, pouring the molten metal is started after lowering the lower plunger to the second position, and lowering the lower plunger to the third position while keeping the upper surface of the molten metal at a substantially constant position from the pouring port. and a mechanism for lowering the upper plunger to lower the lower plunger through the molten metal to a fourth position.