JPH0222124Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement in a non-porous die casting apparatus that supplies and injects reactive gas into a casting cavity.

(Prior art) A die-casting device has a fixed platen 1, a fixed mold 2, and a movable mold 3, as shown in FIG.
and for injecting and press-fitting the molten metal 7 through the runner 5 and the sprue 6 into the cavity 4 which regulates the product shape by the cavity surfaces 2a and 3a formed on the opposing surfaces of the fixed mold 2 and the movable mold 3. It includes an injection sleeve 8, a plunger 9, and a plunger drive device 10. code 1
Reference numeral 1 indicates a spout for injecting molten metal into the injection sleeve 8, and reference numeral 12 indicates a plunger rod. In addition, the non-porous die casting apparatus to which the present invention is directed also includes a reactive gas supply source 20 for supplying a reactive gas such as oxygen into the mold cavity, a supply port 21, and a cavity gas suction. It is further configured to include a discharge mechanism 13 for discharging, and injects molten metal while supplying reactive gas into the cavity of the mold from the supply port 21 and sucking and exhausting the reactive gas which has replaced the air that previously existed. is being done.

(Problems with the Prior Art) In the non-porous die-casting apparatus having such a configuration, the air pre-existing not only in the casting cavity 4 but also in the cavities of the injection sleeve 8, runner 5, etc. is used to remove the air from the metal. It is desirable to completely replace the molten metal 7 with reactive gas before injection.

However, since the plunger 9 disposed within the injection sleeve 8 is moved along the injection sleeve 8, and during this movement, a relatively large circumferential clearance is provided to prevent jamming due to thermal expansion. For this purpose, after replacing the reactive gas, the molten metal 7 is supplied with the plunger 9 positioned as shown in FIG. 6, and then the discharge mechanism 13 is operated to suck and exhaust the reactive gas in the mold cavity. While moving the plunger 9 to the left in the figure to inject the molten metal 7, when the plunger 9 blocks the supply port 21, the supply of reactive gas is stopped, and from then on, the inside of the mold cavity is under negative pressure. becomes injection sleeve 8
Air is introduced from the gap between the mold cavity and the plunger 9, and the concentration of reactive gas in the mold cavity decreases.
This prevents the desired increase in reactive gas replacement rate.

(Objective of the invention) An object of the invention is to further improve the conventional technology and provide a die-casting apparatus that can relatively easily and reliably improve the reactive gas replacement rate in the mold cavity.

(Summary of the invention) The invention is characterized in that the gap between the peripheral surfaces of the plunger is fluidly sealed using a reactive gas, and air flowing into the mold cavity through this gap is preferably blocked.

For this purpose, in the present invention, a nozzle is provided particularly on the circumference or rear side of the plunger (on the side opposite to the molten metal), and the reactive gas is guided to this nozzle and ejected.
This is characterized in that air is prevented from flowing into the mold cavity through the plunger peripheral surface gap.

(Description of the present invention with reference to the drawings) Figs. 1 to 3 show a first embodiment of a plunger portion which is a feature of the present invention. The plunger 9 itself shown here is not essentially different from the conventional one, and the features of the present invention are here embodied in the plunger rod 12'. That is, this plunger rod 12' has a screw hole 1 formed at its tip.
The boss 9a of the plunger 9 can be installed by screwing into the screw hole 12a.
Along the threaded wall surface of a, four grooves 31 are here formed, which grooves 31 are connected to radially oriented notches or nozzles 30 formed in the distal end face of the plunger rod 12'. Further, an internal passage 32 extending in the axial direction is formed inside the plunger rod 12', and the tip of this internal passage 32 is opened at the bottom wall of the screw hole 12a.
At the other end, place the plunger rod 1 at an appropriate position.
It is opened to the outside from 2' and connected to a conduit 33. Although not shown, this conduit 33 is connected, for example, to the same reactive gas supply source 20 (see FIG. 6).

With a plunger part having such a structure,
During die casting, a portion of the reactive gas is guided through the conduit 33 and the internal passage 32 of the plunger rod 12' into the threaded hole 12a in which the plunger 9 is mounted, and can be further injected in the radial direction through the groove 31 from the nozzle 30 at the tip. In this embodiment, such injection of the reactive gas forms a fluid seal at the rear of the plunger 9 by the reactive gas inside and outside the injection sleeve 8. Therefore, this solves the problem caused by the gap between the circumferential surfaces of the plunger as described above.

Figures 4 and 5 show other embodiments of the invention. According to this embodiment, four holes or nozzles 40 are formed here in the radial direction on the circumferential surface of the plunger 9', and an axial internal passage 4 in the plunger 9' leads to the nozzles 40.
1 is opened at the end of the boss 9a. Further, the opening surface of this nozzle 40 is located at a position lower than the circumferential surface of the plunger, and for this reason, the nozzle 40 is
An annular recess 42 is formed on the circumferential surface of the plunger so as to connect the two. On the other hand, the plunger rod 12'' has a structure in which the groove 31 and nozzle 30 are omitted from those shown in FIGS. 1 to 3.

Also in this structure, during die casting, a part of the reactive gas is passed through the conduit 33 and the internal passage 32 to the threaded hole 1 where the plunger 9 is attached.
2a and can be injected radially from a nozzle 40 through an internal passage 41 of the plunger. The reactive gas thus injected forms a fluid seal within the annular recess 42 on the peripheral surface of the plunger.

(Effects of the invention) The die casting apparatus according to the invention provides the following effects.

A reactive gas fluid seal formed at the rear of the plunger prevents outside air from entering the mold cavity through the plunger circumferential gap.

Therefore, since the replacement rate of the reactive gas can be improved, gas hole defects occurring in the cast product due to intruding outside air can be reduced, and a sound die-cast product can be obtained.

The invention can be easily adapted to existing non-porous die casting equipment by replacing the plunger and plunger rod.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a plunger portion which is a feature of the present invention. FIG. 2 is a longitudinal sectional view of the plunger portion of FIG. 1. 3 is a partial perspective view showing the tip of the plunger rod of FIG. 1; FIG. FIG. 4 is a side view showing a plunger portion according to another embodiment. FIG. 5 is a longitudinal sectional view of the plunger portion of FIG. 4. FIG. 6 is an overall schematic sectional view of a die-casting apparatus to which the present invention is applied. 1... Fixed platen, 2... Fixed type, 3... Movable type, 4... Cavity, 5... Runway, 6... Sprue, 7... Molten metal, 8... Injection sleeve, 9...
... plunger, 9'... plunger, 10... plunger drive device, 11... pouring spout, 12... plunger rod, 12'... plunger rod,
12″... Plunger rod, 13... Discharge mechanism,
30, 40... Nozzle, 31... Groove, 32, 41
...internal passage, 33 ... conduit, 42 ... annular recess.

Claims (1)

[Scope of utility model registration request] A nonporous die-casting device that injects molten metal while sucking and exhausting a reactive gas that is supplied into a mold cavity and replaced with air that previously exists, and the peripheral surface of a plunger for injecting molten metal. Alternatively, a die casting device characterized in that a nozzle for ejecting reactive gas from a plunger or plunger rod is provided at a rear position (on the opposite side from the molten metal), and the reactive gas is ejected from this nozzle into an injection sleeve.