JPH049247A - Metallic mold for low pressure casting - Google Patents

Abstract

PURPOSE:To maintain an air vent function over long time without clogging by forming step-like product sticking part to tip end face of pins for air vent. CONSTITUTION:After casting, by retreating side molds 21, 22, the molds are separated from the product. Even if the side molds 21, 22 themselves are separated from the product W, the pins 26 for air vent are not further separated as these are stuck to the product W. Therefore, as the side molds 21, 22 and the pins 26 for air vent are relatively shifted by making the pins 26 for air vent under condition of sticking to the product W, even if flash caused by molten metal is stuck so as to clog this in tip opening part of the air vent facing to a space 7 side of the product part, this flash is fallen down with relative shifting with the above pins 26 for air vent and the side molds 21, 22 and removed, and resultly, self cleaning function is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a low-pressure casting mold, and more particularly to the structure of its air hent.

In the prior art, for example, there is a low-pressure casting mold for the purpose of casting a cylinder head for an internal combustion engine, which has a structure shown in FIG.

This mold 1 consists 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 and forming pairs in the front and rear and left and right directions, respectively (however, the - pair of horizontal molds is shown in Fig. 7). (not shown in FIG. 7 because it is located perpendicular to the plane of the paper), and each of the horizontal molds 4 and 5 can move forward and backward in the horizontal direction on the lower mold 3. It has a structure. A gas vent hole 6 that functions as an air vent is formed in the horizontal types 4 and 5, and the tip of the gas vent hole 6 facing the product part space 7 is an air vent plug in which a slit for gas vent is formed. 8 is installed.

In such a mold structure, the cores 9 and 10 are set, the mold is clamped, and the product space 7 is filled with molten metal such as aluminum alloy through the sprue 11 to perform casting. At 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 66.

After casting, when the horizontal molds 4 and 5 are moved back and released from the product W, and the upper mold 2 is raised, the product W rises while adhering to the upper mold 2, and is further attached to the upper mold 2 side. By lowering the ejector pin 12 along with the ejector plate 13, the product W is released from the upper mold 2 as shown in FIG.

Problems to be Solved by the Invention In the conventional mold structure as described above, as casting is repeated, the air vent plug 8 becomes clogged with molten metal, and unless the air vent plug 8 is replaced, the gas in the product space 7 is blocked. Insufficient discharge may result in blowing, resulting in casting defects such as poor hot water circulation.

In particular, when the air vent plug 8 is installed at a relatively deep position when viewed from the product space 7 side as shown in FIG. 7, cleaning the air vent plug 8 is also difficult, making the above problem even more It becomes noticeable.

The present invention was made in view of the above problems.
The purpose is to provide a structure that can maintain its air vent function over a long period of time without clogging even after repeated casting.

Means for Solving the Problems The present invention provides the horizontal type with an air vent pin that can slide in the same direction as the horizontal type according to the movement of the horizontal type and forms a near air vent between the horizontal type and the horizontal type. When the product is released horizontally from the product based on the above, the step-shaped product bite causes resistance in the direction of releasing the air vent pin from the product, delaying the start timing of the air vent pin releasing operation compared to the starting timing of the releasing operation of the horizontal type. It is characterized in that the attachment part is formed on the tip end surface of the air vent pin.

Effect: According to the above structure, the air vent pin and the horizontal die move relative to each other because the timing at which the air vent pin starts its releasing operation is delayed from the start timing of the releasing operation of the horizontal die itself. As a result, if the gap between the air vent pin that functions as an air vent and the horizontal mold is clogged with flash due to molten metal, the flash will be removed by the relative movement between the air vent pin and the horizontal mold, and A substantially self-cleaning function is exhibited.

Furthermore, even if the flash cannot be removed simply by the relative movement between the air vent pin and the horizontal mold, the tip of the air vent pin protrudes from the molding surface of the horizontal mold due to the above relative movement, making it easier to clean. be able to.

Embodiment FIGS. 1A, 1B, and 1C are diagrams showing an embodiment of the present invention, and parts common to FIG. 7 are given the same reference numerals.

As shown in FIG. 1(A), a holder plate 24 is provided in the receiving space 23 of the horizontal molds 21.22 and is slidable in the horizontal direction with respect to the horizontal molds 21.22. A return pin 25 and an air vent pin 26 extending in the horizontal direction are connected to each other.

The return pin 25 is inserted into a guide hole 27 formed in the horizontal type 21.22, and the air vent pin 26 is inserted into a guide hole 28, respectively. As shown, a slit 29 is formed over its entire length. The slit 29 and the inner wall surface of the guide hole 28 form an air vent 30 that functions as a gas vent hole.

Further, a recess 31 is formed on the tip end surface of the air vent pin 26. These four parts 31 bite into the product W during the solidification process of the molten metal filled in the product space 7, and the air vent pins 26 are separated from the product W when the horizontal molds 21 and 22 are released from the product W as described later. It acts as a part for the product to make it difficult to mold.

Reference numeral 32 in FIG. 1(A) denotes a stop provided on the back side of the horizontal die 21.22 to restrict the retracting limit position of the holder plate 24 with respect to the horizontal die 21.22. When the holder plate 24 comes into contact with the holder plate 24, the tip end surface of the return pin 25 comes into contact with the upper die 2, and the tip end surface of the air vent pin 26 is flush with the molding surfaces of the horizontal die 21, 22 and 33. The position of the stopper 'e-32 and the lengths of the return pin 25 and the air vent pin 26 are set.

According to such a mold structure, when casting is performed by filling the molten metal from the sprue part 11 in the mold clamping state shown in FIG. It is discharged.

After casting, as shown in FIG. 2, the horizontal molds 21.22 are moved back to release the horizontal molds 21.22 from the product W. At this time, the concave portion 31 at the tip of the air vent pin 26 is biting into the product W, and in particular, as shown in FIG. Even if the horizontal molds 21, 22 themselves are released from the product W, the air vent pins 26 still cling to the product W and do not release from the mold.

Therefore, as described above, when the air vent pin 26 remains stuck to the product W, the horizontal mold 21.22 and the air vent pin 26 move relative to each other, for example, the tip of the air vent 30 facing the product space 7 side. Even if there is molten metal flash adhering to the opening that would clog it, this flash will fall off and be removed by the relative movement between the air vent pin 26 and the horizontal die 21, 22.
As a result, it exhibits a self-cleaning function.

Further, the horizontal type 21 and 22 move back and the holder plate 24
When the holder plate 24 comes into contact with the inner wall surface 23a of the receiving space 23, the holder plate 24 starts to move backward with the movement of the horizontal die 21, 22 for the first time from this stage, and as shown in FIG. Release from the mold.

Thereafter, by raising the upper mold 2 from the state shown in FIG. 3 and operating the ejector pin 12, the product W is released from the upper mold 2 as shown in FIG. 4.

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

In this mold open state, compared to the mold closed state, the tip of the veneer bending pin 26 protrudes beyond the molding surface 33 (see FIG. 1(B)), so cleaning can be easily performed. Only cast burrs are left behind.

When the molds are to be clamped in preparation for the next casting, the upper mold 2 is lowered and the horizontal molds 21 and 22 are moved forward as shown in FIG. At this time, the tip of the return pin 25 is
The air vent pin 26 is horizontal type 21.2 until it comes into contact with the
However, when the tip of the return pin 25 comes into contact with the upper mold 2, the horizontal molds 21 and 22 move forward independently. When the horizontal molds 21 and 22 reach the forward limit position, the stopper 32 comes into contact with the holder plate 24, and the tip end surface of the air vent pin 26 becomes 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 in 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. Therefore, it is sufficient that the tip end surface of the air vent pin 26 is formed in some kind of step shape. Therefore, instead of the recess 31 shown in FIG. Even if the convex portion 34 is formed, similar effects can be obtained.

Also, instead of the slit type air vent 30 shown in FIGS. 1(B) and 1(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 an air vent 30.

Note that if the air vent pin 26 is formed with recesses 31 and protrusions 34 as product biting parts, these recesses 3 will be formed on the product W side.
Since a convex portion or a concave portion corresponding to the convex portion 1 or the convex portion 34 will be formed, it is necessary to estimate the cutting allowance in advance to remove the above-mentioned convex portion or concave portion in the subsequent process, or to change the product shape. is required. Therefore, if the product is a cylinder with a 7 card, etc., the position of the air vent pin 26 should be placed in the part corresponding to the so-called cast-out characters such as the identification number 1 year month character 2 letters with a double mark formed on the outer circumferential surface of the product. By setting this, there is no need to change the product shape, etc.

Effects of the Invention As described above, according to the present invention, the timing at which the release operation of the air vent pin starts is delayed from the start timing of the release operation of the horizontal mold itself due to the function of the product biting part, so that the air vent pin and the horizontal mold are relative to each other. Because of the movement, the flash formed by the molten metal poured into 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 poor hot water circulation caused by this clogging.

In addition, even if the flash that has entered the air vent cannot be removed simply by moving the air vent pin relative to the horizontal die,
Due to the above relative movement, the tip of the air vent pin protrudes from the horizontal molding surface, making it easy to clean and reliably remove flash, which also prevents clogging of the air vent. The original function of the air vent can be maintained for a long time.

[Brief explanation of drawings]

FIG. 1(A) is a sectional view showing one embodiment of the present invention, FIG. 1(B) is an enlarged view of part b in FIG. 1(A), and FIG. 2, 3 and 4 are half sectional views for explaining the operation of the mold shown in FIG. FIG. 6 is a sectional view taken along line dd in FIG. 5, FIG. 7 is a sectional view showing an example of a conventional mold, and FIG. FIG. 3 is a sectional view showing a state where the mold is opened. 2... Upper mold, 3... Lower mold, 7... Product section space, 2
1゜22...tti type, 26... pin for air vent, 30... air vent, 311. - Concavity (product biting part), 33... molding surface, 34... convex part (product biting part), W... product (cylinder head). Figure 1 (A) 2-----1213・-m-・Lower mold 7---Seigi-hiru? Pavilion 21.22-1・-Aki! 26-・-2-piece pin 30--1 piece 31--1 concave part (1M face attached) 33---
1 molding surface W----*this U

Claims (1)

[Claims] (1) In a low-pressure casting mold in which casting is performed by filling a product space formed by an upper mold, a lower mold, and a plurality of horizontal molds that are horizontally slidable with respect to these upper and lower molds, the horizontal mold is An air vent pin is provided that can slide in the same direction as the horizontal mold according to the movement of the horizontal mold and forms an air vent between the horizontal mold and the horizontal mold, and when the horizontal mold is released from the product based on the sliding movement of the horizontal mold. A step-like product bite part is formed on the tip surface of the air vent pin, which acts as a resistance in the mold release direction of the air vent pin and delays the start timing of the mold release operation of the air vent pin compared to the start timing of the horizontal mold release operation. A low-pressure casting mold that is characterized by: