JPH0417745B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an injection device for die casting. The injection sleeve and plunger tip, which are the components of die casting injection equipment, can inject high-temperature molten metal at high speed.
It is used for press-fitting into a mold under high pressure, and its normal functioning allows for the high productivity and excellent casting surface that are the characteristics of die casting. However, if the parts of the injection device are damaged for some reason, the injection speed and pressure will immediately become abnormal, making it impossible to obtain a satisfactory casting. In addition, early damage to the injection equipment has a significant impact on die casting costs, so improving the lifespan of the equipment is essential for the practical application of die casting. Conventional injection devices suffer from thermal deformation of the injection sleeve due to repeated exposure to high-temperature molten metal, thermal expansion differences between the injection sleeve and plunger tip, and burrs that occur in the gap between the injection sleeve and plunger tip during molten metal injection. Due to the cause of
There was a problem in that the injection device suffered damage such as so-called galling and lost its function at an early stage. Galling, which is the main cause of damage to the components of the injection device, will be explained below. Galling refers to scratches on the relative sliding surfaces of the injection sleeve and plunger tip, causing the plunger tip to stop or move poorly during injection. This galling is thought to occur when the injection sleeve is deformed by thermal stress or when the difference in thermal expansion between the injection sleeve and the plunger tip becomes large.
A gap 3 was provided between the plunger tip 2 and the plunger shaft 2 in consideration of such an amount of deformation. However, if this gap 3 is made large, there will be no sliding resistance between the injection sleeve 1 and the plunger tip 2 in the blank firing state, resulting in smooth movement, but the pressure during injection will cause the injection sleeve 1 and the plunger tip to move smoothly. Molten metal enters the gap 3 between the plunger tip 2 and generates burrs, and by getting caught in the burrs, the movement of the plunger tip 2 becomes poor, or in severe cases, it stops altogether, resulting in galling. . On the other hand, if the gap 3 between the sleeve 1 and the chip 2 is made too small in order to avoid burrs being caught in it, the sliding resistance will increase and even a slight deformation will cause galling. For these reasons, it is desirable for the injection device to have a gap between the injection sleeve and the plunger tip that is larger than the amount of thermal expansion and deformation, and to prevent burrs from forming in the gap. Usually, injection device parts are designed with this in mind. It has been designed. When molten aluminum has a low melting point and the amount of injection is small, it is possible to design an optimal gap and prevent the occurrence of burrs.
Molten metals made of high melting point materials such as copper and iron have a large amount of deformation and thermal expansion, so it has been difficult to find the optimum gap and prevent burrs. The present invention is intended to solve the aforementioned problems in die casting, such as a decrease in productivity caused by early galling damage to parts of an injection device, an increase in the cost of die casting, and poor casting of castings. For this reason, the present invention includes an injection sleeve having a spout, and a plunger tip that moves together with the plunger rod to inject the molten metal in the sleeve, and the plunger tip has a main body screwed onto the tip of the plunger rod. and a cap-shaped tip portion screwed onto a small diameter portion at the tip of the main body portion, and an annular recess formed on the outer periphery of the tip portion has an outer diameter approximately equal to the inner diameter of the injection sleeve. A plurality of rings each having a cut in a part of the circumference are fitted so that the cuts take different positions in the circumferential direction, and the ring is inserted into the tip portion to prevent the ring from coming out of the annular recess. A regulating protrusion is provided, and an annular ring presser is fitted onto the small diameter portion of the main body portion, the ring presser being held between the main body portion and the tip portion and partially extending over the protrusion to press the ring. did. Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 2 and 3, reference numeral 1 denotes an injection sleeve of an injection device, which has a spout 4. FIG. The plunger tip 2 is operated by a plunger rod 5. The molten metal injected into the injection sleeve 1 through the pouring port 4 is pumped through a hydraulic plunger rod 5.
With the leftward movement of the plunger tip 2,
The injection sleeve 1 is injected to the left and press-fitted into a mold (not shown) connected to its left end. The chip 2 that has completed the injection is returned to the injection starting position after the molten metal has solidified in the mold. The outer diameter of the plunger tip 2 is the same as that of the injection cylinder 1.
Therefore, a sufficient gap 3 is created between the two 1 and 2 to prevent galling. According to the present invention, the plunger tip 2
At the top, a ring 6 approximately equal to the inner diameter of the injection cylinder 1 is provided. It is preferable to provide a plurality of rings 6 as shown in the figure, and these rings 6 are provided with cuts 7, and in order to prevent the molten metal from leaking through these cuts 7, the cuts 7 of these rings 6 are arranged so that each ring 6 has a cut 7 in the circumferential direction of the ring. It is better to take different positions. The ring 6 is made of a metal, such as cast iron, which has wear resistance and has good sliding characteristics with the injection sleeve 1. These rings 6 can be placed axially close together and fit into an annular groove formed in the plunger tip 2 with a width equal to the sum of the axial thicknesses of the rings 6. Now, in a plunger tip having such a ring, if a portion of the plunger tip is damaged, the entire plunger tip must be replaced. In particular, the tip of the plunger tip comes into direct contact with high-temperature molten metal, so it is susceptible to heat damage such as melting and heat checks. The use of expensive heat-resistant alloys may be considered to prevent such damage, but
In this case, the parts that are less affected by heat must also be made of the same material. Furthermore, if the plunger tip is of one-piece construction, the ring must have extremely high dimensional accuracy, which has the drawback of increasing the manufacturing cost of the ring, and furthermore, it is always difficult to replace the ring. An embodiment that avoids these drawbacks, increases the durability of the plunger tip, and facilitates ring replacement is shown in FIG. The plunger tip 2 here consists of a main body part 2a which is screwed onto the plunger rod and a cap-like tip part 2c which is screwed onto a small diameter male threaded part 2b at its free end. Since the tip portion 2c comes into contact with the molten metal during injection, it is made of a heat-resistant alloy and has rounded ends to prevent galling. An annular recess 2d is formed in the tip portion 2c,
A ring 6 is fitted into this recess. It goes without saying that the outer diameter of this ring 6 is selected to be approximately equal to the inner diameter of the injection cylinder. In order to prevent the ring 6 from falling off from the tip portion 2c when the tip portion 2c of the plunger tip is removed from the body portion 2a, a locking protrusion 2 is provided at the right end of the recess 2d in the figure.
e is formed. Note that on the male threaded portion 2b of the main body portion 2a, the main body portion 2a and the tip portion 2
An annular ring retainer 11 is provided between the ring 6 and the ring 6 to prevent wobbling due to variations in the thickness of the ring 6 when the ring 6 is assembled. In addition, in order to prevent the tip portion 2c from galling when the plunger tip 2 retreats due to the molten metal returning to the left end surface of the ring 6 during injection, it is preferable to taper the tip portion 2c so that it is slightly tapered. . It is preferable that the male threaded portion 2b of the main body portion 2a be a left-handed thread, and the female threaded portion 2f for threading into the rod be a right-handed thread. When replacing the ring 6, keep the tip portion 2c of the plunger tip protruding from the tip of the injection sleeve 1 as shown in FIG.
Turn c to remove it from the main body part 2a, and then remove the ring 6.
exchange. In this case, as described above, since the threaded portion 2b is a left-handed thread and the female threaded portion 2f is a right-handed thread, even if the tip portion 2c is loosened, the threaded connection between the main body portion 2a and the plunger rod 5 will not loosen. Note that 12 indicates a fixed die plate, and 13 indicates a fixed mold. Next, the results of experiments conducted on the embodiment shown in FIG. 2 will be explained below. Experimental example 1 Four rings 6 made of material equivalent to FCD40, 5 mm thick, with a gap of 0 to 0.05 mm between the injection sleeve and the cut 7, are installed on the plunger tip 2 with the cuts 7 offset from each other in the circumferential direction. , a material equivalent to FC23 was cast using the die-casting method. The injection sleeve 1 is made of SKD-61 material, which has been heat treated to improve its hardness.
I used one tempered to about HRC45. The injection conditions were: pouring temperature 1300-1350℃, molten metal pressure 700Kg/cm ² ,
The injection speed was set at 0.4 to 1.0 m/sec, and the pressure and speed were measured for each shot to check for abnormalities in the injection conditions. As a result, 800 shots were continuously cast, and there were no abnormalities in either pressure or speed, which always showed stable values. Furthermore, the sliding surfaces of the injection sleeve and plunger tip were inspected for galling after 800 shots, but no galling was observed. Experimental example 2 A ring with the same shape as experimental example 1 was used as FCD70.
It was manufactured using comparable materials and die-casting molten aluminum with a large casting weight. Experimental Example 3 A ring with the same shape as Experimental Examples 1 and 2 was made of copper alloy, and in combination with an injection sleeve made of a heat-resistant alloy, a ring with a higher melting point than cast iron was produced under the same injection conditions as Experimental Example 1. die casting of molten stainless steel. The results of Experimental Example 1 are shown in the following table. This table shows the number of injections (shots) before the injection equipment part becomes unusable as a measure of lifespan.

[Table] As can be seen from this table, by using the ring, it was possible to eliminate galling between the injection sleeve and the plunger tip, and the life of the injection equipment parts was increased by 10 to 20 times compared to the conventional method. In addition, since galling does not occur, both the pressure and speed during injection are stable, and the rejection rate of castings is significantly reduced. As explained above,
According to the die casting injection device according to the present invention,
Since there is no gap between the inner surface of the injection sleeve and the plunger tip, not only burrs but also galling can be prevented, greatly extending the life of the plunger tip. Therefore, manufacturing costs can be reduced by selecting appropriate materials for each part, and safety is also increased since the protrusion prevents the ring from falling off when the plunger tip is disassembled.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a conventional injection device, Fig. 2 is a longitudinal cross-sectional view of an embodiment of the present invention, Fig. 3 is a perspective view of its main parts, and Fig. 4 is a partially cutaway view of another embodiment. FIG. 5 is a side view for explaining the disassembly work. 1...Injection sleeve, 2...Plunger tip, 3...Gap, 4...Pouring port.

Claims (1)

[Claims] 1. An injection sleeve having a spout, and a plunger tip that moves together with the plunger rod to inject the molten metal in the sleeve, and the plunger tip has a main body portion screwed to the tip of the plunger rod, and a main body portion of the main body portion. a cap-shaped tip part screwed onto a small diameter part of the tip, and a part in the circumferential direction having an outer diameter approximately equal to the inner diameter of the injection sleeve and having an annular recess formed on the outer periphery of the tip part. A plurality of rings with cuts in the ring are fitted so that the cuts take mutually different positions in the circumferential direction, and a protrusion is provided at the tip portion to prevent the rings from coming off from the annular recess. Injection for die casting, characterized in that an annular ring retainer is fitted into the small diameter portion of the main body portion, the ring presser being held between the main body portion and the tip portion and partially extending over the protrusion to press the ring. Device.