JPS6310056A - Mold for low pressure casting of metal die for vulcanizing tyre forming - Google Patents

Abstract

PURPOSE:To facilitate the forming of a sprue runner and to perform a molten metal pouring economically by filling the fire resisting insulation material having plural recessed grooves extending to the external part with the pouring gate as the center on the inner face of the lower die of the upper and lower dies containing a core and forming a sprue runner in the space with the lower face of the base plate placing the core on. CONSTITUTION:The gypsum member 1 for casting has the same shape as the tyre outer surfaces and is fixed by being co-axially placed on the fire resisting insulation base plate 2 of a thin discoid shape. The material of the gypsum member for casting is used for the plate 2, but ceramics, etc., can be used as well. On the other hand the main die M composed of the upper and lower dies 3, 4 is the same as the known die but the sprue runner communicating to the space of the cavity 11 of the outer periphery of the gypsum member 1 for casting from a pouring gate 9 is formed at the lower part of the plate 2 by the radial recessed groove 8 formed on the inner face of the lower die 4 and plate 2. The molten metal ascending through a stroke 10 fills up the inside of the cavity 11, passing the sprue runner. Consequently the forming of the sprue runner is easy and the molten metal circulates inside the cavity uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a low-pressure casting mold for a tire molding and vulcanization mold (hereinafter simply referred to as a tire mold).

(Prior art) In the casting of tire molds, a method called low-pressure casting, in which a cast product is formed by applying pressure to a molten metal, such as an aluminum alloy molten metal, and causing it to rise through a stalk, is currently being adopted. It is being

The adoption of this method for tire mold casting has been extremely effective in solving the problems of conventional gravity casting, but there are still various drawbacks, so further improvements have been made. , Part or all of the sprue push provided near the stalk or sub-riser connection part is made of a heat insulating material (Japanese Utility Model Publication No. 54-28416),
Casting gypsum segments having substantially the same shape as the outer surface of the tire are placed on a thick fireproof insulation base to form a core, which is made up of an upper mold and a lower mold lined with a fireproof insulation layer. A type 18 has been proposed (Japanese Patent Publication No. 11383/1983) which is placed in a main mold and forms a circular runner with the lower and side surfaces of a fireproof heat insulating base and a lining fireproof heat insulating layer.

(Problems to be Solved by the Invention) However, in the former proposal, for example, the distance to the cavity is small and its capacity is small, so even though it is effective to some extent in terms of heat insulation of the runner,
It is unsuitable for applications that require a large amount of molten metal, such as for large tire molds, and even if the latter can be improved, the base on which the plaster segment for casting is placed is thick (and therefore the main As the capacity of the mold becomes unnecessarily large, the space for filling the molten metal within the mold also becomes large (which poses problems in maintaining the uniformity of the molten metal and in economic efficiency).

The present invention addresses the above-mentioned circumstances and aims to simplify the structure of the runner and the holding of the gypsum segment members, thereby solving the above-mentioned problems all at once.

(Means for Solving the Problems) That is, a feature of the present invention that satisfies the above object is that, in the low-pressure casting mold for the tire mold, a runner is formed on the inner surface of the lower mold of the main mold. The recessed groove is filled with a refractory heat-insulating filler for runners, which is formed in a plurality of strips on the upper surface facing outward in a straight radial or curved blade shape at appropriate angular intervals around the sprue, and the above-mentioned gypsum member for casting. A plurality of runners are formed in the lower part of the base plate by the upper surface of the fire-resistant heat-insulating base plate for placing and holding the fire-resistant heat-insulating base plate and the grooves on the upper surface of the fire-resistant heat-insulating filler, which communicate from the sprue to the cavity space around the outer periphery of the casting plaster member in the main mold. It's in the structure of things.

Here, the width and depth of the groove may be the same throughout its length, but from the viewpoint of being suitable for directional solidification and allowing the flow of molten metal from the sprue to flow uniformly with less fluctuation. It is preferable to form the sprue so that it becomes thinner and shallower as it goes outward from the sprue, and it is also effective to round the corners.

Note that the plurality of radial or curved blade-shaped concave grooves extending outward from the sprue are not necessarily limited to one place on the inner surface of the lower mold, but may be placed at two or more places from above the even distribution of the molten metal. It is particularly effective for mold molding of large tires.

(Function) After the above-mentioned mold of the present invention aligns the upper and lower molds of the main mold containing the core to position and set the casting position, compressed air or When compressed gas is blown in, the gas pressure causes the molten metal, such as aluminum alloy, in the holding furnace to rise from the bottom of the stalk through the inside of the stalk, divide into multiple runners from the sprue at the top of the stalk, and flow into the mold. is filled with.

The filled molten metal is directionally solidified from the upper part of the mold toward the sprue while being subjected to gas pressure applied to the surface of the molten metal, and a desired tire mold is formed in the upper part of the base plate.

(Example) Hereinafter, specific examples of the mold of the present invention will be described with further reference to the accompanying drawings.

FIG. 1 shows a main part of a low-pressure casting apparatus for a tire mold using the mold of the present invention, and FIG. 2 shows an aspect of forming a runner.

In these figures, (1) is a gypsum member for casting, and (2) is a relatively thin plate-shaped fireproof heat insulating base plate on which the gypsum member for casting (1) is placed and held.
A core (C) is formed by both +1+ (21), and is housed in a main mold (M) consisting of an upper mold (3) and a lower mold (4).

Here, the casting plaster member (1) has an outer surface substantially the same shape as the outer surface of the tire in order to fit the outer surface of the tire, and is usually divided into an appropriate number of segments and is a thin disc. It is placed and fixed concentrically on a fireproof and heat insulating base plate (2) having a shape.

In addition, as mentioned above, the fireproof heat insulating base plate (2) is formed into a disk shape with a relatively thin wall, and its material is usually a material for casting plaster members, but it is not necessarily limited to this. , ceramic materials, etc. can also be used.

However, it is preferable that the material has substantially the same coefficient of body expansion as the gypsum member for casting.

On the other hand, the main mold (M) consisting of an upper mold (3) and a lower mold (4) is similar to the known mold, but the molten metal rises to the upper surface on the inner surface of the lower mold (4). At least a plurality of radial recesses 1 (81
is filled with a fireproof insulating material (5) for runners in which a runner is formed, and a sprue (9) is formed at the bottom of the base plate (2) by the plurality of grooves (8) and the fireproof heat insulating base plate 2).
) Casting plaster member (1) outer cavity (11)
It forms a radial runner that communicates with the space.

In addition, the above-mentioned fireproof insulation material (
5) may be cast plaster as described above, but may also be other materials with the same effect such as ceramics.

In the figure, (6) is a sealing member, (7) is casting sand, for example Cot.
The sealing member (6) can also be filled with asbestos or foundry sand similar to the above-mentioned core sand.

The mold of the present invention has the configuration as described above, and currently has a stalk of 0.
As in known low-pressure casting, the molten metal such as aluminum alloy passes through the sprue (9) and
It enters the cavity space (11) around the outer periphery of the casting plaster member (1) through the runner formed by the recessed groove (8) of the fireproof insulation base plate (2) and the fireproof insulation material (5), and fills it. .

Then, the filled molten metal is directionally solidified sequentially from the upper part according to the outer surface shape of the casting gypsum member (1), and a tire mold is formed. At this time, although not shown, the gas generated in the mold is appropriately vented through the gas vent hole of the upper mold.

In this way, a tire mold can be finally obtained by low pressure casting.

(Effects of the Invention) As described above, the present invention fills the inner surface of a lower mold with a fireproof heat insulating material having a plurality of straight radial or curved grooves extending outward from a sprue, and also mounts a plaster member for casting. The base plate to be held in place is formed relatively thin, and both of them form a plurality of runners that communicate from the sprue to the cavity space around the outer periphery of the casting gypsum member. It is easy to form a runner because it forms a plurality of runners, and
Not only does the molten metal flow smoothly and uniformly into the cavity, but wasteful filling of the molten metal, such as in an annular runner, is prevented, and the molten metal can be distributed and filled in an economical manner.

Further, since the fireproof heat insulating material that receives the casting plaster member is relatively thin, there is no wastage of space within the main mold, and it is easy to utilize the space to the maximum extent.

Furthermore, as mentioned above, since the concave grooves are provided on the upper surface of the fireproof insulation material to form a runner, it has an excellent heat-insulating effect, and the molten state of the molten metal in the runner can be maintained uniformly and well, making it suitable for directional solidification. It also has the effect of obtaining high-quality tire mold castings, and is expected to be industrially effective as a low-pressure casting mold.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a low-pressure casting apparatus for a tire mold using a mold according to the present invention, and FIG. 2 is a schematic plan view showing a state in which a runner is formed. (1)...Gypsum member for casting. (2) Fireproof insulation base plate (C) Core. (3)...Upper mold 1 (4)...Lower mold. (?'l) ...main type. (5) Fireproof insulation material. (8)...concave groove. (9) ... sprue. (10)...Stoke. (11)...Cavity.

Claims (1)

[Scope of Claims] 1. A core consisting of a casting gypsum member having substantially the same shape as the outer surface of the tire, a fireproof and heat insulating base plate for mounting and holding the member, and both upper and lower sides in which the core is housed. The lower mold of the main mold has a plurality of concave grooves on its upper surface that extend outward in a straight or curved manner at appropriate angular intervals around the sprue. When the core is housed in the main mold, a plurality of runners are connected to a cavity on the outer periphery of the casting gypsum member in the main mold through the plurality of grooves and the lower surface of the fireproof heat insulating base plate. A low-pressure casting mold for a tire molding and vulcanization mold, characterized in that it is formed by forming: 2. The low-pressure casting mold for a tire forming and vulcanizing mold according to claim 1, wherein the groove on the upper surface of the fireproof heat insulating material for a runner is formed to become narrower and shallower as it goes outward from the center.