JP2565785Y2 - Casting mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a mold suitable for relatively large individual castings of 1 ton or more as-cast.

<Conventional technology> Conventionally, molds made of self-hardening sand used for individual castings are classified into two types: a case where the skin sand that comes into contact with the molten metal and the back sand behind it are not properly used, and a case where the sand is separately used. The method has been adopted.

The cast iron mold and the relatively small cast steel mold can be formed with a single sand by sufficiently improving the quality of the reclaimed sand without using the sand and the back sand properly. However, in the case of a mold for large cast steel, it is necessary to use a sand sand and a back sand, and to use a casting sand having high heat resistance as the skin sand.

A typical example of a conventional large cast steel mold will be described with reference to FIG. The figure is a cross-sectional explanatory view at the time of lower mold molding, where a model 03 and a casting frame 04 are placed on a molding platen 02 on a floor 01, and a part that contacts molten steel on the surface of the model 03 while constructing a runner 05. The sand sand a having a high heat resistance is laid, and the back sand b having a low heat resistance is filled behind the sand a, and the shaping and the filling of the back sand b are alternately repeated.

<Problem to be Solved by the Invention> In FIG. 5, inexpensive recovered sand with poor fire resistance is used as the backing sand b, but the surface sand a is replaced with new silica sand or special sand with high heat resistance. (Zircon sand, Chromite sand) and other molding sands with high heat resistance are required.

These skin sands a are expensive, and it is necessary to thinly put the skin sand a on the model 03 in the casting flask 04. The surface of the skin sand is heat resistant
Although sanding of about 10 mm is sufficient, general molding sand such as furan sand has high fluidity, so it is difficult to thinly fill the side of the model, and the average sanding is 40 to 50 mm. As a result, expensive skin sand a is present at unnecessary locations inside the mold.

In addition, during molding, it is necessary to repeat the filling of the skin sand a and the filling of the back sand b in a narrow casting flask 04, so that not only is it time-consuming to fill, but also the casting quality varies due to uneven plating and uneven filling of the skin sand a. In addition, it is necessary to work for a long time by bending down in a casting flask in which the environment in which dust and reaction gas of the kneading sand drift is poor.

Note that a space is required between the side surface of the model 03 and the casting flask 04 so that the skin sand a can be laid, which leads to deterioration of the ratio of sand metal.

Further, when acid-curable furan sand or the like is used, hot cracking due to the adverse effect of sulfur is likely to occur. And the mold is model 03
Is transferred, so that high model surface accuracy is required, and it is necessary to apply a release agent so that skin sand b does not adhere to the model surface.

<Means for solving the problem> In order to solve this problem, the present invention provides a projection on the back surface of the shell plate molded by the shell molding machine, and attaches the shell plate to a flat portion that hits skin sand. The present invention proposes a mold characterized by that.

<Function> In the mold of the present invention, a plate-shaped shell (hereinafter, referred to as a shell plate) formed by shell molding machine, that is, formed by firing shell sand and having high room temperature strength and non-plasticity (hereinafter referred to as a shell plate). Paste on a flat surface that hits the sand, fill the back sand behind the shell plate to form a mold, while the corner where the shell plate can not be constructed, the part where the skin sand is easy to construct and the part composed of curved surface are It uses skin sand kneaded as described above.

<Example> Hereinafter, the present invention will be specifically described based on an example shown in the drawings.

FIGS. 1 to 3 show perspective views of shell plates, and FIG. 4 shows cross-sectional views of application states of the shell plates in a mold according to an embodiment of the present invention.

The shell plate of FIG. 1 has an L-shape C with a step on one piece, and the shell plate of FIG. 2 has a step D on each side to form a concave D with a concave cross-sectional shape. The shell plate has a reverse-slope sand E fixed on the back surface with an adhesive to form a reverse-slope E. All three have a shape in which the shell plate is hard to peel off from the mold when the mold is removed, and in particular, the reverse-slope mold E shown in FIG. 3 can be applied to the overhang portion of the mold.

As shown in FIG. 4, in this embodiment, a model 3 and a casting frame 4 are placed on a molding platen 2 of a floor 1, and a vertical lower portion 3a of a plane of the model 2, which is a portion to be in contact with molten steel, at the time of mold removal. Since the model pulling load is large, concave D shell plates are arranged, runner 5 is set, back sand b is filled, and L-shaped C
Are arranged, and a reverse-slope E-shell plate is arranged in the overhang portion 3c where peeling is most difficult. The corner 3d where the shell plate cannot be applied and the portion 3e where the sand can be easily applied
Uses the skin sand A, and uses the back sand c for the model baseboard 3f and other portions that do not come into contact with the molten steel.

The simple shell plate as described above is used for the mold of the present invention. These shell plates can be manufactured with a certain high strength and high quality by mechanical molding using a shell machine (shell molding machine). In other words, in the shell molding machine, the shell plate is formed by firing the shell sand coated with the phenol resin, and the shell plate formed by the shell molding machine becomes a non-plastic shell mold having high room temperature strength. The shell plate is
It has a high resistance to pressure, has a small gas generation amount, can withstand strong molten steel pressure, and can maintain dimensional accuracy. For this reason,
The following improvements were made by installing the shell plate in a tile shape on the plane part of the model.

Since the shell plate does not contain sulfur, when applied to an acid-curable furan sand mold or the like, the adverse effect of sulfur from the mold was reduced. In addition, since the shell plate is molded by a machine, the packing density is constant, so that high-quality mold sand is formed and the casting quality is improved.

By applying the shell plate on the flat part of the model, the embedding of skin sand was omitted, the molding time was shortened, and the working posture was improved. In addition, the ratio between the sand frames was reduced due to the reduction between the model flasks.

The thickness of the shell plate can be kept to the minimum required in millimeters, eliminating wasteful parts such as hand scales, and reducing sand costs.

In addition, resource saving of foundry sand was promoted, and the dependence of imported sand on foreign countries decreased.

The model to which the shell plate can be applied does not require the application of a mold release agent, not only does not need to improve the model surface accuracy, but also can simplify the model structure mainly composed of the model bone.

<Effects of the Invention> As described above, according to the mold of the present invention, a simple shell plate having high heat resistance as described above is used, and the shell plate is constructed in a tile shape on the plane portion of the model. As a result, it is possible to shorten the molding time, improve the working posture, reduce the cost of foundry sand, save resources of foundry sand, improve the as-cast quality, and simplify the model.

[Brief description of the drawings]

1 to 3 are perspective views showing the shapes of shell plates according to an embodiment of the present invention, FIG. 4 is an explanatory diagram showing a lower mold section in a mold molding state using these shell plates, and FIG. The figure is an explanatory view showing a lower mold section during molding using two kinds of sand, skin sand and back sand. In the drawing, 1 is a floor, 2 is a surface plate, 3 is a model, 4 is a casting frame, 5 is a runner, 3a
Is the vertical lower part of the model plane, 3b is the vertical part of the model, 3c is the overhang part, 3d is the corner part, 3e is the part where the kneading sand is easy to install, 3f is the model baseboard part, A is the skin sand, B is the back Sand, C is L-shaped,
D is a concave type, and E is a reverse gradient type.

Claims (1)

(57) [Scope of request for utility model registration] 1. A mold wherein a projection is provided on the back surface of a shell plate formed by a shell molding machine, and the shell plate is adhered to a flat portion hitting skin sand.