JPH0150504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection method and apparatus for a die-casting machine, and particularly relates to an injection method and an apparatus for injection molding in a die-casting machine.
That is, the present invention relates to an injection method and apparatus for performing casting by changing the positions of an injection sleeve, an injection plunger, and a plunger tip relative to the amount of molten metal.

In die-casting machines, the quality of the molded product is significantly affected by whether or not the molten metal can be cast into the mold cavity while minimizing the temperature drop of the molten metal, which is in a high-temperature state. This is because the viscosity of the molten metal increases as the temperature of the molten metal decreases, causing poor flow of the molten metal within the mold cavity. Therefore, since it is necessary to inject the molten metal into the mold cavity in the shortest possible time, the die casting machine is required to have a high injection speed. However, as the injection speed increases,
The surface of the molten metal inside the injection sleeve or mold cavity becomes turbulent and scatters, which entrains the atmosphere and contains air bubbles during the molding process. Therefore, voids other than the substance of the molten metal, ie, cavities, are formed in the molded product, which often causes problems in terms of strength, pressure resistance, and liquid resistance of the molded product.

As is clear from the above explanation, in order to obtain a good die-cast molded product, it is necessary to cast at a low speed without disturbing the molten metal surface, and by shortening the time it takes for the molten metal in the injection sleeve to move into the mold cavity. That would be a good thing.

In order to shorten the transfer time of the molten metal, it is best to minimize the distance the molten metal moves from the injection sleeve to the mold cavity, but since the amount of molten metal varies depending on the shape of the molded product, it is difficult to use a single injection sleeve. Unable to cope with variable amount of molten metal.

In order to deal with this problem, in the present invention, the positions of the injection plunger and the plunger tip relative to the injection sleeve are changed so that the distance traveled by the molten metal from the injection sleeve to the mold cavity is always maintained even if the amount of molten metal is different. This makes it easier to obtain optimal casting conditions.

Next, explanation will be given based on an actual device.

BACKGROUND ART Conventionally, as an example of a vertical die-casting machine, a device as shown in FIGS. 1 to 6 has been used.

In the figure, 1 is a movable mold, 2 is a fixed mold,
3 is a mold cavity, 4 is an injection sleeve, 5 is a plunger tip slidably provided within the injection sleeve 4, 6 is a block provided integrally with the injection sleeve 4, and 7 is the plunger tip 5 attached to the tip. 8 is an injection cylinder, 9 is a shaft for tilting the injection cylinder 8, 10 is the molten metal, 11 is a ladle, and 12 is a collar provided at the connection between the piston rod 13 of the injection cylinder 8 and the plunger 7. It is a convex part due to etc. plunger tip 5
and plunger 7 form an injection plunger.

The block 6 is formed into a hollow conical shape. A flange-shaped engaging portion 14 is formed inside the lower end of this block 6.
The upper surface of the piston rod 4 engages with the outer periphery of the lower surface of the protrusion 12, which is formed using a coupling or a collar or the like below the coupling that connects the piston rod 13 and the plunger 7. Then, when the block 6 is raised, the engaging portion 14 holds the convex portion 12 and the convex portion 12
This also ensures that the plunger tip 5 and the injection sleeve 4 can always rise simultaneously.

A cylinder 15 is formed in the vertical direction within the block 6, and the tip of a ram 16 fixed to the rod end side of the injection cylinder 8 is slidably fitted into the cylinder 15. The structure is such that hydraulic oil is supplied from a source through the ram 16 into the cylinder 15 to raise the block 6.

Next, the operation of the device will be explained.

FIG. 1 shows that by means of a tilting device (not shown),
The entire injection device is tilted and molten metal 10 is poured into the injection sleeve 4 from the ladle 11. Next, the entire injection device is rotated about the shaft 9 and stands upright. This is shown in FIG. Then the third
As shown in the figure, by introducing hydraulic pressure into the cylinder 15 through port c, the block 6 rises,
The injection sleeve 4 fits into the fixed mold 2. At this time, the plunger 7 is pulled up through the convex portion 12 by the rise of the block 6, so there is no change in the relative positions of the injection sleeve 4 and the plunger tip 5, and the plunger 7 rises all the time, without shaking the molten metal. Next, by introducing hydraulic pressure into the chamber of the injection cylinder 8 through port a, the plunger 7 and the plunger tip 5
begins to rise, and along with this, the molten metal 10 begins to rise toward the cavity 3 formed by the molds 1 and 2.

4 and 5 show only the cavity 3, injection sleeve 4, and plunger tip 5 of the mold. As shown in FIG. 4, the molten metal 10 rising inside the injection sleeve 4 enters the runner 17 in the fixed mold 2, passes through the gate 18, and enters the cavity 3. Figure 5 shows that the molten metal 10 is in the cavity 3.
It represents a state of being filled with.

Here, the L dimension in FIG. 4 is defined as the distance the plunger tip 5 moves from the retreated position shown by the two-dot chain line to the position where the molten metal 10 reaches the gate 18 of the cavity 3 as shown by the solid line. During this time, the molten metal radiates heat significantly, so
At the same time, the viscosity increases, causing poor water circulation within the cavity 3. Of course, it is desirable to set this L dimension to zero, but in reality, as shown in FIG. As shown in , a runner distance L2 is required. Therefore, L ₀
The movement distance of =L-(L1+L2) is a harmful and useless movement that only promotes cooling of the molten metal.

After injection, hydraulic pressure is guided from port b to chamber e of the injection cylinder 8 to lower the injection sleeve 4, plunger tip 5, etc.

In the present invention, the harmful and useless moving distance L ₀ of the injection plunger can be set to O.

In addition, in the conventional method and apparatus shown in FIGS. 1 to 6, when the maximum amount of molten metal is not required, that is,
It is not preferable to inject the molten metal by appropriately changing the amount of molten metal injected at a time to a desired amount.

That is, in order to always accurately stop the plunger tip 5 at a desired position in the space above the maximum lowering limit position relative to the injection sleeve 4, there is no mechanical stopper, so the stopping position varies and it takes a considerable amount of time. difficult.

Furthermore, if the amount of hot water supplied is small and the convex portion 12, which is a part of the plunger 7, is apart from the engaging portion 14 of the block 6, when docking the injection sleeve 4 to the mold 2, the injection sleeve 4 and the block 6 and plunger tip 5 and plunger 7
It is extremely difficult to maintain the same positional relationship and raise them at the same speed. The reason for this is that the cylinder 15 in the block 6 for raising the injection sleeve 4 and the injection cylinder 8 for raising the plunger tip 5
This is because it is very difficult to supply hydraulic oil into the d chamber on the head side of the pump so that the injection sleeve 4 and the plunger tip 5 always rise at the same speed.

Of course, if the injection sleeve 4 and the plunger tip 5 do not rise while keeping their relative positions constant, the molten metal may fly out or the plunger tip 5 may slip out from under the injection sleeve 4, which is extremely dangerous. Moreover, variations occur in the amount of molten metal poured, making it impossible to obtain a good molded product.

Next, the present invention will be explained with reference to embodiments shown in the drawings.

In the figures, the same parts as those shown in Figs. 1 to 6 are designated by the same reference numbers, and the explanation thereof will be omitted.

FIG. 7 shows an embodiment for reducing the moving distance L ₀ to zero, and in this example, the injection plunger for the injection sleeve 4 is arranged between the convex portion 12 and the engaging portion 14 according to the amount of hot water supplied. This is achieved by inserting a spacer 19, which is an injection start position adjustment member, so that the relative position of the plunger tip 7 and the plunger tip 5 is at the lowest lower limit position.

Then, when the molten metal is put into the injection sleeve before injection starts, the retraction limit position of the injection plunger tip surface is adjusted according to the amount of molten metal in the injection sleeve so that the top surface of the molten metal can be positioned near the top surface of the injection sleeve. When changing in advance before supplying hot water into the injection sleeve, an injection start position adjusting member is provided between the member connected to the injection sleeve and a part of the injection plunger to adjust the injection start position of the injection plunger with respect to the injection sleeve, i.e. , a spacer 19 is provided to adjust the injection start position of the injection plunger with respect to the injection sleeve to a desired position, and in this state, molten metal is supplied into the injection sleeve, and then the relative positions of the injection sleeve and the injection plunger are adjusted. The injection sleeve was attached to the mold while keeping the temperature constant, and then injection was performed. Spacer 19
By constructing a plurality of spacers 19 and preparing various thicknesses of each spacer 19, it is possible to immediately respond to any amount of molten metal.

As shown in FIG. 7, the thickness of the spacer 19 is _L0 , and the retraction limit position of the plunger tip 5 when the spacer 19 is not used is as shown by the two-dot chain line, and the retraction limit position is as shown by the solid line. When the spacer 19 is used, the distance between the plunger tip 5 and the retraction limit position is _L0 .

FIGS. 8 and 9 show another embodiment. FIG. 8 shows a screw adjusting member 21 screwed into the engaging portion 14 of the block 6 for adjusting the position of the plunger tip 5 relative to the injection sleeve 4 before starting injection.
The relative positions of the injection plunger 7 and the plunger tip 5 with respect to the injection sleeve 4 can be finely adjusted steplessly.

Further, FIG. 9 shows an example in which the screw adjustment member 21 illustrated in FIG. 8 can be remotely controlled, so that the operator of the machine can arbitrarily adjust the position without approaching the injection device. The amount of molten metal can be adjusted. Note that 22 is a gear and 23 is a motor, which are attached to the lower part of the block 6.

In the embodiments described above, the spacer 19 and the screw adjustment member 21 can be referred to as a position adjustment member that adjusts the injection start position of the injection plunger 7 with respect to the injection sleeve 4.

As described above, in the present invention, the retraction limit position of the injection plunger tip surface is changed according to the amount of molten metal in the injection sleeve by the action of the position adjustment member, etc., and the molten metal is introduced into the injection sleeve before injection starts. Since the top surface of the molten metal is positioned near the top surface of the injection sleeve during injection, even if the amount of molten metal in the injection sleeve before injection starts is different, the distance that the molten metal moves from the injection sleeve to the mold cavity is always the same. This makes it easier to obtain optimal casting conditions.

This greatly reduces the possibility of a drop in the temperature of the molten metal, an increase in the viscosity of the molten metal, or poor flow of the molten metal within the mold, and also prevents cavities from forming in the product due to surrounding air being drawn in during injection. This makes it possible to easily obtain injection products with excellent strength, pressure resistance, and liquid resistance.

Of course, in the present invention, an injection start position adjusting member is used between a member connected to the injection sleeve and a part of the injection plunger, so that the relative positions of the injection plunger and the plunger tip with respect to the injection sleeve are at the lowest lower limit position. Sometimes, by bringing a part of the injection plunger into contact with the injection start position adjustment member, before supplying the molten metal into the injection sleeve,
The relative positions of the injection plunger and plunger tip with respect to the injection sleeve are mechanically regulated in advance according to the amount of hot water supplied.
There is no variation in the amount of hot water supplied into the injection sleeve, and after the hot water is supplied into the injection sleeve, the relative positions of the injection sleeve and the plunger tip can be kept constant at all times, raised, and docked into the mold. Therefore, it is easy to obtain high quality molded products,
Moreover, there are no dangerous situations and work can always be carried out safely.

[Brief explanation of drawings]

Figures 1 to 6 show an example of a conventional device, each showing a longitudinal sectional view showing the operating sequence, and Figures 7 to 9 showing a longitudinal sectional view showing different embodiments of the device for carrying out the method of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 1... Fixed mold, 2... Movable mold, 3... Cavity, 4... Injection sleeve, 5... Plunger tip, 6... Block, 7... Plunger, 8
... Injection cylinder, 10 ... Molten metal, 12 ... Convex part, 14 ... Engagement part, 15 ... Cylinder, 16 ...
... Ram, 19 ... Spacer, 21 ... Adjustment member.

Claims (1)

[Claims] 1. When molten metal is put into the injection sleeve before injection starts, the tip surface of the injection plunger is adjusted in accordance with the amount of molten metal in the injection sleeve so that the top surface of the molten metal can be positioned near the top surface of the injection sleeve. When changing the retraction limit position of the injection sleeve beforehand before supplying hot water into the injection sleeve, the injection start position of the injection plunger relative to the injection sleeve is adjusted between a block provided integrally with the injection sleeve and a part of the injection plunger. An injection start position adjustment member is provided to adjust the injection start position of the injection plunger relative to the injection sleeve to a desired position. In this state, molten metal is supplied into the injection sleeve, and then the injection sleeve and injection plunger are An injection method for die-casting machines in which the injection sleeve is attached to the mold while maintaining a constant relative position, and then injection is performed. 2. In an injection device for a die casting machine that injects molten metal from an injection sleeve into a mold cavity using an injection plunger slidably inserted into the injection sleeve, a convex portion is provided in the middle of the injection plunger, and the injection plunger is integrated with the injection sleeve. An engaging portion located on the rear side of the convex portion of the injection plunger is provided on a block provided in the injection cylinder so as to be movable in the axial direction with respect to the injection cylinder. An injection device for a die-casting machine that is provided with an injection start position adjustment member that adjusts the injection start position of an injection plunger to a desired position. 3. An injection device for a die-casting machine according to claim 2, wherein a spacer that can be inserted between the convex portion of the injection plunger and the engaging portion of the block is used as the injection start position adjusting member. 4. An injection device for a die-casting machine according to claim 2, wherein the injection start position adjustment member is an adjustment member screwed onto the engaging portion of the block so as to be movable in the axial direction.