JP2575714B2 - Mold casting method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a die casting method used for manufacturing camshafts and the like.

(Problems to be solved by the prior art and the invention) Generally, in mold casting, the cooling rate is high,
It is well known that a chill layer of high hardness is easily formed on the surface of a molded article. When a camshaft is manufactured by a mold casting method having such characteristics, the entire surface of the molded product is chilled. However, in the case of the camshaft, the surface of the nose is required to be chilled because high hardness is required to withstand contact with the mating member. ,
Rather, considering the necessity of cutting after casting,
A method that does not chill is desirable. Given this fact,
In manufacturing a camshaft, if a mold casting method that has been frequently used is adopted, the entire surface of the camshaft, which is a molded product, is desirably formed even though it is desirable to partially form a non-chilled portion. It is chilled, and there is a problem that the above demand cannot be met. From this point, it has been an important issue in the mold casting method to devise a method for manufacturing a molded product having a part that is partially non-chilled. A method of installing an inoculant (i.e., an impurity that promotes solidification from the inside of a molten metal) at an appropriate position in a mold cavity to make the site non-chilled is well known, There is a problem that the installation of the inoculant inside the cavity involves technical difficulties.

The present invention has been made in view of the above points, and has an object to enable a molded product manufactured by a mold casting method to be partially chill-free by an extremely simple method. .

(Means for Solving the Problems) In the present invention, as means for solving the above problems, a plurality of split molds having a molding surface forming a cavity together with a mold body are slid with respect to the mold body. Prepare a casting mold supported as possible, fill the cavity with the molten metal, hold it for a predetermined time and wait for solidification of the molten metal, slide the split mold to form a molded product and a split mold. A gap is provided at a predetermined interval between the molds, and the molded article is held for a predetermined time in that state, the portion molded on the molding surface of the split mold is made non-chilled, and then the mold is released.

(Operation) In the method of the present invention, the following effects are obtained by the above means.

That is, a molten metal is filled into a cavity formed by a mold body and a split mold slidably supported with respect to the mold body, and after the melt is solidified, the split mold is slid to perform molding. By forming a gap at a predetermined interval between the product and the molding surface of the split mold, the surface cooling rate of a portion corresponding to the split mold forming surface in the molded product due to the heat retention of the air filled in the gap. Of the chill at the site is prevented, and the chill that has already occurred at the site before the split slide can be disassembled, thereby making it possible to partially eliminate the chill by extremely simple means. It is.

(Example) Hereinafter, a mold casting method of the present invention will be described based on a casting apparatus shown in the attached drawings.

As shown in FIG. 1, the casting apparatus of this embodiment includes a fixed mold 4 fixed to a fixed frame 2 fixed on a base 1 and shafts 6 and 6 mounted horizontally on the base 1. It comprises a movable mold 5 fixed to a movable frame 3 which is guided and retreated, and a cavity 7 is formed between the two molds 4 and 5 by combining them. That is, the fixed mold 4 and the movable mold 5 constitute a casting mold.

The fixed mold 4 and the movable mold 5 each include a mold body 4a.
And 5a, and a plurality of split dies 4b, 4b... And 5b, 5b
・ ・ It consists of On the inner surfaces of the mold bodies 4a and 5a, nose portions 8a, 8a,.
.. And 10, 10,... For molding (see FIG. 3) are formed, while the mold bodies 4a and 5b are provided on the inner surfaces of the split dies 4b and 5b. Forming surface for forming a connecting portion 8b (see FIG. 3) of a camshaft 8 to form a cavity 7 for camshaft casting together with 5a.
11, 12 are formed respectively. That is, in a state where the two dies 4 and 5 are united and the split dies 4b, 4b... And 5b, 5b. 7 are formed. The split molds 4b, 4b ... and 5b, 5b ...
・ The connecting rods 15,15
. And 16, 16,..., And these operating plates 13, 14 are moved forward and backward by cylinders 17, 18 provided on the fixed frame 2 and the movable frame 3, respectively. I have.

In the drawings, reference numeral 19 denotes a cylinder for moving the movable frame 3 forward and backward.

Next, a method of manufacturing a camshaft using the illustrated casting apparatus will be described.

First, as shown in FIG. 1, the fixed mold 4 and the movable mold 5 are combined, and the divided molds 4b, 4b... And 5b, 5b.
··· is positioned at the forward end, and a cavity 7 for camshaft casting is formed between the dies 4 and 5, and the cavity 7 is filled with molten metal via a runner (not shown) (see FIG. 2). . After filling the molten metal, the state is maintained for a predetermined time to allow natural cooling. The cooling time is determined by the shape, thickness, and the like of the molded product 8, and generally, the thickness of the molded product 8 is defined as t. At this time, the temperature is around the temperature at which (1025-25t) ° C. is reached, and the cooling time is set to a temperature of 870 ° C. or more at which the self-annealing action is obtained. When the molten metal filled in the cavity 7 solidifies after the natural cooling, the operation plates 13, 14 are moved backward by the operation of the cylinders 17, 18, so that the split dies 4b, 4b. , 5b ... are retracted by a small amount (for example, several mm), and the molded product 8 and the split dies 4b, 4b ...
And 5b, 5b ... molding surfaces 11, 11 ... and 12, 12
.. gaps S, S... Are formed between. Then, air having a temperature of 870 ° C. or more is sealed in the gaps S, S, and the split molds 4b, 4b,.
, 5b, 5b,... (Ie, the camshaft connecting portions 8b, 8b,...) Have a reduced surface cooling speed to prevent chilling, and the self-annealing action of the split dies 4b, 4b , And 5b, 5b, which are already generated before retreating, are also decomposed. Therefore, the camshaft 8, which is a molded product, has chilled nose portions 8a, 8a,.
.., 8b... After maintaining the above state and cooling for a predetermined time (that is, until the self-annealing action is completed), the movable mold 5 is retracted to release the camshaft 8, thereby producing a camshaft by die casting. Is completed.

As described above, according to the present embodiment, after filling the molten metal into the cavity 7 and solidifying the molten metal, the split dies 4b, 4b... And 5b, 5b. 8 and the molding surfaces 11, 11 ... and 12, 12 ... of the split dies 4b, 4b ... and 5b, 5b ...
..Dividing type by extremely simple method of forming
The portions corresponding to the molding surfaces 11, 11 ... and 12, 12 ... of 4b, 4b ... and 5b, 5b ... (that is, the camshaft connecting portions 8b, 8b ...) are not chilled. The camshaft 8 as a molded product can be partially chill-free.

In the above embodiment, the case where the camshaft is manufactured by die casting has been described. However, the method of the present invention is applicable not only to the manufacture of camshafts but also to the case of manufacturing members having different thicknesses by die casting. Of course.

(Effects of the Invention) As described above, according to the method of the present invention, a plurality of split molds having a molding surface forming a cavity together with a mold body are formed by:
Prepare a casting mold slidably supported on the mold body, fill the cavity with the molten metal, hold for a predetermined time and wait for solidification of the molten metal, slide the split mold, A gap is provided at a predetermined interval between the molded product and the molding surface of the split mold, and after maintaining the molded product for a predetermined time in that state, the mold is released. As a result, the surface cooling speed of the portion corresponding to the divided mold forming surface in the molded product is reduced, and chill is prevented from being generated at that portion, and the chill that has already been generated at that portion before the split mold slide operation is performed is also divided. As a result, there is an excellent effect that the molded article can be partially chill-free by extremely simple means.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a casting apparatus used in the mold casting method of the present invention. FIG. 2 is an enlarged view of a main part showing a state in which a cavity is filled with a molten metal in the casting apparatus of FIG. The figure is an enlarged view of a main part showing a state of the casting apparatus of FIG. 1 at the time of a split type slide operation. 4 Casting mold (fixed mold) 5 Casting mold (movable mold) 4a, 5a Mold body 4b, 5b Split mold 7 Cavity 8 Molded product (camshaft) 11,12 …… Molding surface S …… Void

Claims (1)

(57) [Claims] 1. A casting mold comprising a plurality of split molds having a molding surface forming a cavity together with a mold body is slidably supported on the mold body, and a molten metal is filled in the cavity. After filling, hold for a predetermined time and wait for solidification of the molten metal, slide the split mold to provide a gap at a predetermined interval between the surface of the molded product and the molded product of the split mold, and in this state, form the molded product for a predetermined time. Wherein the part formed on the molding surface of the split mold is made non-chilled, and then the mold is released.