JPH064998Y2 - Mold for casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to the structure of a mold used for mold casting.

(Prior Art) In cast molding, the method of filling the cavity with the molten metal has a great influence on the occurrence of non-uniformity of the structure of the cast product and the occurrence of internal defects (for example, in Japanese Patent Laid-Open No. 62-9762) A molten metal filling method is disclosed).

By the way, mold casting with a metal mold is advantageous in terms of productivity and environmental improvement as compared with casting using a sand mold,
In addition, since there is an advantage that the structure of the casting is made finer and the strength is improved, the current usage tends to increase.

This die casting includes push-up gravity casting, which has the advantages of being economical because it can be loaded in large numbers, and that the quality of the casting is likely to be stable.

An example of a mold used for this gravity casting will be described with reference to FIG. In addition, although a pair of molds are combined and used for casting, only one side is shown here.

The die 1 is provided with a sprue 2, a runway 3 and a cavity 4 in which a product is cast. The spout 2 is opened on the upper surface of the die 1 and extends in the vertical direction. Has a runner 3 branched in the horizontal direction, and is formed so as to connect the sprue 2 and a cavity 4 for molding a casting. A sprue bottom 5 is provided downward from a branch point between the sprue 2 and the sprue 3, and the sprue bottom 5 is formed in an arc surface shape. A rise 6 is provided above the cavity 4. In addition, 7 shows the pipe line for flowing cooling water.

Then, when the molten metal is injected from the sprue 2 during casting, the injected molten metal hits the spout bottom 5 and is filled into the cavity 4 through the runner 3.

(Problems to be Solved by the Invention) However, the gravity casting mold 1 having the above structure has the following problems.

The molten metal injected from the sprue 2 falls and collides with the spout bottom 5 and scatters. At this time, the molten metal may cause a turbulent flow and may entrap air. However, when the molten metal is filled in the cavity 4 and cast while the air is entrained in this way, a defective product having a gas defect, a so-called pinhole, is produced. Will be manufactured.

Further, if the particles of the molten metal that have collided and scattered at the bottom 5 of the spout solidify alone, a defective product having a molten metal will be produced.

As described above, there is a problem that various defective products are manufactured by the molten metal colliding and scattering at the bottom 5 of the spout.

The present invention has been made in view of the above problems, and an object thereof is to provide a casting mold in which defective products are prevented from being generated by reducing scattering due to collision of molten metal at the bottom of a sprue. Especially.

(Means for Solving the Problem) A first means for solving the above problems according to the present invention is a bottom of a sprue provided in a vertical direction, and a spout for communicating the spout with a cavity. An inverted cone-shaped sprue bottom is formed at a position below the branch point of, and the apex angle of the inverted conical shape of the sprue bottom is set to 30 degrees or more and 60 degrees or less. The vertical angle of the inverted cone is 30 degrees or more and 90 degrees or less, and the depth of the cylinder at the bottom of the sprue is at least 20 mm.
It is characterized by the above.

(Function) In this way, the bottom of the sprue is shaped like an inverted cone, and the apex angle of this inverted cone is set to 30 degrees or more and 60 degrees or less, or the angle of the inverted cone of the sprue bottom is set to 30 degrees or more and 90 degrees or less, and By setting the depth of the cylindrical portion at the bottom of the sprue to be at least 20 mm or more, the dropped molten metal collides with the sloped sprue bottom, so that the impact is softened and scattering is reduced. Therefore, it is possible to prevent the entrainment of air in the molten metal and the generation of molten metal balls.

(Example) Next, the Example of this invention is described based on drawing. 1 is a perspective view showing an example of the casting mold of the present invention,
FIG. 2 is a schematic view showing the bottom of the sprue of the present invention. Further, since the casting mold 8 of the present embodiment is different from the conventional casting mold 1 shown in FIG. 5 only in the shape of the bottom of the sprue, the same parts are designated by the same reference numerals and the detailed description will be omitted. Omit it.

The die 8 is formed with an inverted conical sprue bottom 9 at the bottom of the sprue 2 and below the branch point between the sprue 2 and the runner 3. The lower end of the inverted cone-shaped sprue bottom 9 is formed into an arc surface.

With such a shape of the bottom of the sprue, the molten metal injected from the sprue 2 drops and collides with the spout bottom 9 having an inverted conical shape as in the case of the conventional mold. At this time, most of the molten metal is the sprue. The impact is softened by the collision with the slope 9a of the bottom 9, and as a result, the amount of the molten metal scattered at the time of the collision is significantly reduced.

Then, the occurrence of gas defects caused by the inclusion of air and the generation of molten metal defects caused by the solidification of the scattered molten metal are reduced.

Next, the result of a test for comparing the state of occurrence of defects in a cast product molded using the mold 8 of the present invention and the conventional mold 1 will be described.

In the test, the bottom 9 of the gate 8 of the mold 8 of the present invention was set as follows with the respective dimensions shown in FIG.

A (diameter of opening of sprue bottom 9) = 15mm R (radius of lower end of sprue bottom 9) = 2mm T (diameter of sprue 3) = 5mm θ (1/2 of apex angle of cone of sprue bottom 9) = 15 °, 30 °, 45 °, 60 °, 90 °, 100 ° x (Cylinder depth of the sprue bottom 9) = 10,20,30mm Also, the sprue bottom 5 of the conventional die 1 is the sixth The dimensions shown in the figure were set as follows.

R '(Radius of the bottom of the sprue bottom 5) = 7.5mm x' (Depth of the cylindrical part of the sprue bottom 5) = 10,20,30mm The cavity shape is a disk shape with a diameter of 100mm and a thickness of 10mm. Is spheroidal graphite cast iron (FCD), C = 3.6%, Si
= 2.4%, Mg = 0.01 to 0.03% was used.

After casting, the gas defect and the molten metal defect of the cast product were measured. The gas defect was measured by measuring the area of the cavity taken by X-ray photography of the cast product, and taking the total as the gas defect amount. In addition, the molten metal defect was obtained by cutting the cast product at intervals of 10 mm, counting the molten metal appearing on the cut surface, and taking the total as the number of molten metal defects. 10 test samples were prepared.

The results of this test are shown in FIGS. 3 and 4.

From the results of this test, with the conventional shape of the sprue bottom 5, the deeper the depth (x ') is, the more the amount of gas defects and the number of molten metal defects are reduced, but this cannot be completely prevented. Further, if the depth of the bottom 5 of the sprue is increased, the yield is deteriorated, and further, there is a problem that the run-up failure is likely to occur due to the poor run-up property.

On the other hand, in the shape of the spout bottom 9 of the present invention, when θ (1/2 of the apex angle of the cone) is 30 ° or less, the amount of gas defects and the number of molten metal defects are irrespective of the depth (x). It turns out that it has not occurred at all. Further, as the depth of the spout bottom 9 becomes deeper, the amount of gas defects and the number of molten metal defects tend to decrease, but there is no difference when the depth (x) is 20 mm or more. When the depth is 20 mm or more, the gas defect amount and the number of molten metal defects hardly occur until θ is 45 ° or less.

In this way, by setting the θ (vertical angle 1/2) of the sprue bottom 9 to be 30 ° or less, it is possible to provide a cast product in which the amount of gas defects and the number of molten metal defects do not occur at all.

(Effects of the Invention) As described in detail above, the present invention is a mold for gravity casting in which the apex angle is 30 degrees or more at the top of the gate.
Since the vertical angle is 30 degrees or less, or the apex angle is 30 degrees or more and 90 degrees or less, and the depth of the cylindrical portion at the bottom of the sprue is at least 20 mm or more, the amount of scattering when the injected molten metal collides decreases. It is possible to prevent the occurrence of gas defects, molten metal defects, etc., reduce the production of defective products, and significantly improve the yield.

Further, when the bottom of the sprue has an inverted conical shape, thermal shock is reduced, which is advantageous for thermal damage, and also has an effect of extending the life of the mold.

[Brief description of drawings]

FIG. 1 is a perspective view of a casting mold of the present invention, FIG. 2 is a schematic view showing an example of the shape of the bottom of the gate of the present invention, and FIG. 3 is cast by the present invention and a conventional mold. FIG. 4 is a diagram showing the amount of gas defects in a cast product, FIG. 4 is a diagram showing the amount of hot water defects in a casting product cast by the present invention and a conventional mold, and FIG. 5 is an example of a conventional casting mold. FIG. 6 is a schematic view showing an example of the shape of the sprue bottom of a conventional casting mold. 2 ... gate 3 ... runner 4 ... cavity 9 ... gate bottom

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Minoru Uozumi 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (56) References Micro film (JP, U) of the detailed description and drawings attached to the application

Claims (2)

[Scope of utility model registration request] 1. An inverted-cone shaped sprue bottom is formed at a bottom portion of a sprue provided in a vertical direction and at a position below a branch point between the sprue and a runner communicating the gavity with each other. A mold for casting, characterized in that the apex angle of the inverted cone shape is 30 degrees or more and 60 degrees or less. 2. An inverted conical sprue bottom is formed at a bottom portion of a sprue provided in a vertical direction at a position below a branch point of a spout connecting the sprue and a cavity. The mold for casting is characterized in that the apex angle of the inverted cone shape is 30 degrees or more and 90 degrees or less, and the depth of the cylindrical portion at the bottom of the sprue is at least 20 mm or more.