JP2553221B2 - Low pressure casting mold - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure casting mold, and more particularly to a structure of an air vent portion thereof.

2. Description of the Related Art For example, there is a low-pressure casting mold having a structure shown in FIG. 7 for casting a cylinder head of an internal combustion engine.

This mold 1 is composed of an upper mold 2 and a lower mold 3, and two sets of horizontal molds 4 and 5 arranged on the lower mold 3 in pairs in the front-rear direction and the left-right direction (however, one set of the horizontal molds is (It is not shown in FIG. 7 because it is located in the direction orthogonal to the paper surface of FIG. 7) and each horizontal mold 4 and 5 can move forward and backward in the horizontal direction on the lower mold 3. It has a simple structure.
The horizontal molds 4 and 5 are formed with a gas vent hole 6 that functions as an air vent, and an air vent plug in which a gas vent slit is formed at the tip of the gas vent hole 6 facing the product space 7. 8 is installed.

In such a mold structure, the cores 9 and 10 are set and then the mold is clamped, and a molten metal such as an aluminum alloy is filled from the sprue part 11 into the product part space 7 for casting. This time,
The gas in the product space 7 is discharged to the outside of the mold through the air vent plug 8 and the gas vent hole 6.

After casting, when the horizontal molds 4 and 5 are retracted to separate from the product W and then the upper mold 2 is lifted, the product W is lifted while being attached to the upper mold 2 and further attached to the upper mold 2 side. By lowering the ejector pin 12 that is present together with the ejector plate 13, the product W is released from the upper mold 2 as shown in FIG.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the conventional mold structure as described above, the air vent plug 8 is clogged by the molten metal while casting is repeated, and unless the air vent plug 8 is replaced, the gas in the product part space 7 If the discharge is insufficient, it will be blown, and casting defects such as defective molten metal will occur.

In particular, as shown in FIG. 7, when the air vent plug 8 is mounted at a relatively deep position as seen from the product part space 7 side, it is difficult to clean the air vent plug 8, so that the above-mentioned problems are further caused. It becomes remarkable.

The present invention has been made in view of the above problems, and an object thereof is to provide a structure capable of maintaining an air vent function for a long period of time without causing clogging even when casting is repeated. To do.

Means for Solving the Problems The present invention provides a horizontal die with an air vent pin that is slidable in the same direction as the horizontal die according to the movement of the horizontal die and that forms an air vent between the horizontal die and the horizontal die. Based on the above, it becomes a resistance in the release direction of the air vent pin from the product at the time of horizontal release from the product and delays the release operation start timing of the air vent pin from the horizontal release operation start timing. It is characterized in that the attached portion is formed on the tip surface of the air vent pin.

Action According to the above structure, the air vent pin and the horizontal die move relative to each other because the release operation start timing of the air vent pin lags behind the release operation start timing of the horizontal die itself. As a result, in the unlikely event that the gap between the air vent pin that functions as an air vent and the horizontal die is blocked by the molten metal, the flash is removed by the relative movement of the air vent pin and the horizontal die, Substantially self-cleaning function.

Further, even if the flash is not removed only by the relative movement between the air vent pin and the horizontal die, the relative movement causes the tip surface of the air vent pin to project from the molding surface of the horizontal die, so that cleaning is easily performed. be able to.

Embodiments FIGS. 1 (A), (B), and (C) are views showing an embodiment of the present invention, and the portions common to FIG. 7 are designated by the same reference numerals.

As shown in FIG. 1 (A), the receiving spaces 2 of the horizontal molds 21 and 22
A holder plate 24 that is slidable in the horizontal direction with respect to the horizontal molds 21 and 22 is provided in the reference numeral 3, and a return pin 25 and an air vent pin 26 that extend in the horizontal direction are connected to the holder plate 24. .

The return pin 25 is a guide hole 27 formed in the horizontal type 21 and 22.
In addition, the air vent pins 26 are inserted into the guide holes 28, respectively.
As shown in (C), a slit 29 is formed over the entire length. The slit 29, the guide hole 28, and the inner wall surface form an air vent 30 that functions as a gas vent hole.

A recess 31 is formed on the tip surface of the air vent pin 26. The recess 31 bites the product W in the process of solidification of the molten metal filled in the product space 7, and the air vent pin 26 is released from the product W when the horizontal molds 21, 22 are released from the product W, as described later. It serves as a biting part for products that make it difficult to mold.

Reference numeral 32 in FIG. 1 (A) is a stopper provided on the back side of the horizontal molds 21 and 22 for restricting the retracting limit position of the holder plate 24 with respect to the horizontal molds 21 and 22, and as shown in FIG.
When the holder plate 24 comes into contact with the
The position of the stopper 32, the return pin 25, and the air vent pin so that the front end surface of the air mold pin 25 is in contact with the upper mold 2 and the front end surface of the air vent pin 26 is flush with the molding surfaces 33 of the horizontal molds 21 and 22. 26 lengths are set.

According to such a mold structure, when the molten metal is filled from the sprue part 11 and casting is performed under the mold clamping state of FIG. 1 (A), the gas in the product part space 7 is passed to the outside through the air vent 30. Is discharged.

After casting, as shown in FIG. 2, the horizontal molds 21, 22 are retracted to separate the horizontal molds 21, 22 from the product W. At this time, the recess 31 at the tip of the air vent pin 26 is biting into the product W,
In particular, as shown in FIG.
Since the biting on the surface 31a parallel to the sliding direction of the is a resistance, even if the horizontal molds 21 and 22 themselves are separated from the product W, the air vent pin 26 still sticks to the product W and does not separate. .

Therefore, as the air vent pin 26 remains stuck to the product W as described above, the horizontal molds 21, 22 and the air vent pin 26 move relative to each other, so that, for example, the tip of the air vent 30 facing the product space 7 side. Even if a molten metal flash that clogging the opening is attached to the opening, this flash will not be removed by the air vent pin 26 and the horizontal mold 21,2.
It falls off and is removed by relative movement with 2, and as a result, it exhibits a self-cleaning function.

When the horizontal molds 21, 22 are further retracted and the holder plate 24 contacts the inner wall surface 23a of the receiving space 23, the holder plate 24 starts to retract with the movement of the horizontal molds 21, 22 for the first time from this stage. As shown in the drawing, the air vent pin 26 is released from the product W.

Thereafter, the upper die 2 is lifted from the state shown in FIG. 3 and the ejector pins 12 are operated to release the product W from the upper die 2 as shown in FIG.

If the flash flash adhered to the air vent 30 is not removed by the self-cleaning function described above, the air vent 30 is cleaned using a brush or the like in the mold open state as shown in FIG.

In this mold open state, the tip of the air vent pin 26 has a molding surface 33 (see FIG. 1B) as compared with the mold closed state.
Since it protrudes more than that, cleaning can be performed easily, and no unburned flash remains.

Further, when the die is clamped in preparation for the next casting, as shown in FIG. 1, the upper die 2 is lowered and then the horizontal dies 21, 22 are advanced. At this time, the air vent pin 26 advances together with the horizontal molds 21 and 22 until the tip of the return pin 25 comes into contact with the upper die 2, but the tip of the return pin 25 does not.
After that, the horizontal molds 21 and 22 independently move forward. When the horizontal molds 21, 22 reach the forward limit position, the stopper 32
Comes into contact with the holder plate 24, and the air vent pin 26 and the tip end surface are flush with the molding surface 33 as shown in FIG. 1 (B).

Here, the function of the product biting part is mainly to increase the resistance on the plane parallel to the operating direction of the air vent pin 26 to make it difficult to release the air vent pin 26 from the product W as described above. The air vent pin
It suffices if the tip surface of 26 is formed in a stepped shape in some way. Therefore, the same as the case where the convex portion 34 is formed as shown in FIG. 5 instead of the concave portion 31 shown in FIG. 1 (B). The effect is obtained.

Instead of the slit type air vent 30 shown in FIGS. 1 (B) and (C), a gap 35 is provided between the air vent pin 26 and the guide hole 28 as shown in FIGS. 5 and 6. This may be used as the air vent 30.

If the concave portion 31 or the convex portion 34 is formed on the air vent pin 26 as the product biting portion, a convex portion or a concave portion corresponding to the concave portion 31 or the convex portion 34 is formed on the product W side. In the above, it is necessary to allow for a cutting allowance for cutting and removing the above-mentioned convex portions and concave portions in advance, or to change the product shape. Therefore, when the product is a cylinder head or the like, by setting the position of the air vent pin 26 at a portion corresponding to so-called casting characters such as an identification number, a year / month character, a date character, etc. formed on the outer peripheral surface of the product. Therefore, it is not necessary to change the product shape.

As described above, according to the present invention, the release operation start timing of the air vent pin is delayed from the release operation start timing of the horizontal die itself due to the function of the product biting portion, so that the air vent pin and the horizontal die are relatively opposed to each other. From moving
The flash produced by the molten metal entering the air vent is removed by the relative movement. As a result, it is possible to prevent clogging of the air vent as in the conventional case, and to prevent casting defects such as blowing and defective molten metal run due to the clogging.

In addition, even if the relative movement between the air vent pin and the horizontal die does not remove the flash that has entered the air vent, the relative movement above causes the tip surface of the air vent pin to protrude from the horizontal molding surface, so cleaning it It is easy to remove the flash and it is possible to prevent clogging of the air vent and maintain the original function of the air vent for a long time.

[Brief description of drawings]

FIG. 1 (A) is a cross-sectional view showing an embodiment of the present invention, FIG. 1 (B) is an enlarged view of part b of FIG. 1 (A), and FIG. 1 (C) is c of FIG. 1 (B). Sectional views along line c, FIGS. 2, 3, and 4 are half sectional views for explaining the operation of the mold of FIG. 1A, and FIG. 5 is another embodiment of the present invention. FIG. 6 is a sectional view taken along the line d-d in FIG. 5, FIG. 7 is a sectional view showing an example of a conventional mold, and FIG. 8 is a mold in FIG. It is sectional drawing which shows the state which opened the type | mold. 2 ... Upper mold, 3 ... Lower mold, 7 ... Product space, 21,22 ...
… Horizontal type, 26 …… Air vent pin, 30 …… Air vent,
31 …… Recessed portion (part that bites the product), 33 …… Molding surface, 34 ……
Convex part (product biting part), W ... Product (cylinder head).

Claims (1)

(57) [Claims] 1. A low-pressure casting mold for casting by filling a molten metal into a product part space formed by an upper mold and a lower mold and a plurality of horizontal molds that can slide horizontally with respect to these upper and lower molds. In addition, provided with an air vent pin that is slidable in the same direction as the horizontal die in accordance with the movement of the horizontal die and forms an air vent between the horizontal die, when releasing the horizontal die from the product based on the horizontal die sliding operation. The end face of the air vent pin has a stepped product biting part that delays the release operation start timing of the air vent pin from the product as the resistance in the release direction of the air vent pin from the product. A low-pressure casting mold characterized by being formed in.