JPH0455039A - Casting mold - Google Patents

Abstract

PURPOSE:To surely suppress the formation of a half solidified melt by molding a base part communicating with the cavity of a vent groove as a flow regulating throttle port of an extremely small sectional area, communicating the large-diameter side of a tapered vent groove with the outer side thereof and forming the sectional area on the side open to the atm. to the diameter smaller than the diameter of the sectional area on the large-diameter side. CONSTITUTION:The base part communicating with the cavity 3 of the vent groove 4 which is communicated at one end with the cavity 3 provided in the molds 1, 2 and is communicated with the other ends with the atm. on the outside of the molds 1, 2 is formed to the extremely small sectional area to provide the flow regulating throttle port 5. The large-diameter sectional side of the tapered vent groove 6 provided with a convergent taper on the outer side of the flow regulating throttle part 5 is communicated with this port and the outflow sectional area (a) of the side open to the atm. is formed to the diameter smaller than the diameter of the outflow sectional area A on the large-diameter section side. Then, the flow regulating throttle part 5 and the molten metal advance and arrive at the small-diameter side of the vent groove 6 and since the molten metal is half solidified, the groove is powerfully clamped and the jumping out force is suppressed. Since the length of the vent groove 6 is short, the lump of the oil generated in the groove is blown off and the perfect gas venting is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly relates to a mold for casting such as die casting, and more specifically, it is an invention that relates to a mold for casting such as die casting. This invention relates to a casting mold with improved gas vent grooves.

[Conventional technology]

It has been known to provide a gas vent in communication with a cavity for discharging the air inside the mold when molten metal is press-fitted in a casting operation. On the mold mating surfaces of the mold (A) and the fixed mold (B), a mold parallel to the mold mating surfaces is formed through a molten metal (water reservoir) etc. that communicates with the cavity (C). The thickness was approximately 100%, and a gap was provided between the long distances to form gas vent grooves (e).

[Problem to be solved by the invention]

The gas venting groove described in the conventional technology is 0.05 to 0°25%.
Creating a gap with a thickness of approximately However, due to the way die casting is used, it is difficult to completely prevent blowholes from forming in any part of the casting. When the molten metal comes into contact with the mold surface, the contact surface instantly becomes semi-solidified and forms a thin solidified film. A selective flow of molten metal is generated that pushes through a portion of the coagulated film in the weak part of the solidified part and spews out toward the tip.This phenomenon is repeated many times and the molten metal spouts out, causing the mold gas vent groove to be closed. It would have been dangerous if it was not kept long (approximately 100%). For this reason, when the mold release agent and lubricating oil come into contact with the molten metal at 700°C, vaporize, and move through the gas vent groove, the mold temperature is as low as approximately 150°C, so it is cooled and liquefied, turning into highly viscous oil. do.

Therefore, the gas vent groove is completely sealed with high viscosity oil, making it impossible for gas to blow out. Therefore, gas remains and it is difficult to fill the molten metal sufficiently, which causes cavities, creases, etc.
This was the cause of many occurrences of hot water spots, sink marks, and blisters.

The present invention has been made in view of these problems of the conventional technology, and its purpose is to achieve almost complete degassing effect in molten metal, regardless of the shape of the product, etc. The purpose of the present invention is to provide a casting Venus having a gas vent groove that can be expected to yield high-quality and sound castings.

[Means to solve the problem]

In order to achieve the above object, 1 the casting mold of the present invention is provided with a rectifying orifice by forming the base of one end communicating with the capitol of the gas vent groove to have an extremely small cross-sectional area, and communicating with the rectifying orifice to provide an outer side thereof. It is preferable that the large-diameter cross-section side of a tapered gas vent groove having a tapered slope be communicated with each other, so that the outflow cross-sectional area on the side open to the atmosphere is smaller in diameter than the outflow cross-sectional area on the large-diameter cross-section side.

[Effect]

Since the rectifying orifice is narrowed to an extremely small cross-sectional area, the molten metal is prevented from flowing out until the cavity is completely filled and pressure is generated, and the molten metal is completely filled into the cavity. As soon as this is completed, high pressure is generated, and against the restraining force, it is ejected all at once from the rectifying orifice at high pressure and high speed, and it travels straight to the mold on the small diameter side of the tapered gas vent groove. When it comes into contact with the surface, it becomes semi-solidified and a frictional force is generated, the molten metal at the tip stops, and the following molten metal β completes filling the remaining part on the large diameter side of the taper gas vent groove, and at the same time pressure increases in the taper gas vent groove. occurs and pushes the semi-solid molten metal α at the tip forward, and as the semi-solid molten metal α is pushed forward and moves, the slope is set so that the cross-sectional area on the tip side becomes narrower. Due to the sloped mold surface that naturally becomes narrower as it goes towards the thinner side,
The pressing movement force in the diagonal direction is the opposite phenomenon to the strong lateral spread caused by driving a wedge, so the component force of the movement force in the diagonal inward direction acts inward in the perpendicular direction and is more centered than the periphery.・Power is generated by strong tightening towards the part, and the semi-solidified molten metal is strongly tightened from the surroundings, becoming even stronger and stopping, and the subsequent molten metal is trapped in the remaining part of the large diameter side of the taper gas vent groove. Even if pressure is generated when the melt is filled, there will be no gushing because the tip is solidified, which prevents the dangerous selective flow of hot water that tries to push out the weaker parts and pop out. It can be definitely prevented.

〔Example〕

Examples will be explained with reference to the drawings.

In Figures 1 to 4, one end side communicates with a cavity formed inside the mating surfaces of the movable mold l and the fixed mold 2, and the other end side opens to the end face of the mold and is open to the atmosphere. A rectifying throttle opening 5 is provided by forming the base of one end of the gas venting groove 4 which is provided in the gas venting groove 4 in communication with the cavity 3 to have an extremely small cross-sectional area. Then, the large-diameter cross-section side of the tapered gas vent groove 6, which is connected to the rectifying throttle port 5 and has a tapered slope on the outside thereof, is communicated with the flow-out cross-sectional area A on the atmosphere-opening side. at
-A>a. Furthermore, the test values that yielded good results in the present invention are detailed below based on FIG.

Example 1゜Product shape: Ring Casting force: 250 tons Casting speed: Maximum thickness of the gap between the gas vent grooves forming the rectifying orifice 5 S
:0.25% Length of gas vent groove forming rectifying orifice 5
K: Dimensions of the communication groove between the 0.5% rectifying throttle port 5 and the tapered gas venting groove 6 M: 0.7% The dimension of the gas venting groove forming the cross section A on the cavity side (large diameter side) of the tapered gas venting groove 6 Thickness of the gap T: 0.7% Thickness of the gap of the gas vent groove that constitutes cross section a on the atmosphere side (small diameter side) of the tapered gas vent groove 6 t: 0.1
5% Length L of the amount of slope forming beads between T: 8% Length t of the portion where the thickness of the gas vent groove after the slope is t = 0.15: 3% [Effects of the invention] Tests based on examples The results showed that there were no occurrences of hot water wrinkles, hot water spots, blisters, porosity, etc. that had conventionally occurred, and it was possible to obtain a firm, high-quality product with a uniform gloss. Therefore, when the present invention is carried out, the molten metal that has become evenly pressurized from the rectifying orifice advances straight and reaches the narrow diameter side of the tapered gas vent groove and becomes a semi-solidified state. In order to suppress the conventional selective flow of hot water that pops out while pushing and spreading, the present invention strongly tightens the molten metal by using a slope-changing tightening force using an oblique slope surface to suppress the popping force.
There is no fear of the molten metal splashing out due to the selective flow of the metal, and the length of the gas vent groove can be extremely short.Because the length of the gas vent groove is short, it is easy to blow away the oil that forms inside the gas vent groove. Complete degassing can be achieved and a high quality product can be obtained.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the main part of the casting mold, Figure 2 is a vertical cross-sectional view of the main part showing the solidification state of the molten metal, Figure 3 is a vertical cross-sectional view of the casting mold, and Figure 4 is a vertical cross-sectional view of the casting mold. A side view as seen from the mating surface, and FIG. 5 is a longitudinal sectional view of a conventional casting mold.

Claims (1)

[Claims] 1. One end of the base communicates with a cavity provided in the mold,
In a gas venting groove whose tip end side of the other end communicates with the atmosphere outside the mold, the base of one end communicating with the cavity side of the gas venting groove is formed to have an extremely small cross-sectional area to provide a rectifying orifice, and the rectifying orifice is provided. The large-diameter cross-section side of the tapered gas vent groove, which is connected to the opening and has a tapered slope on the outside thereof, is communicated with the outflow cross-sectional area of the large-diameter cross-section side (
A casting mold characterized in that the outflow cross-sectional area (a) on the side open to the atmosphere is formed to have a smaller diameter than A).