JPH01118405A - Concrete block molding die - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance of a mold in addition to its filling property and mold release characteristics by a method in which in order to thin the wall thickness of the molding face composed of nodular graphite cast iron, a recessed portion is formed on the lower surface-side of the outer periphery of the mold, and the case hardening of a specified hardness is applied to the lower surface-side of the die. CONSTITUTION:As the material of molding face, nodular graphite cast iron is used, and its microtexture has the texture in which crystallized graphite is mixed with crystallized cementite. To improve the abrasion resistance of the edge of lower surface-side, the minuteness of cast iron-texture and the crystallization of carbide are increased by forming a recessed portion and thinning the wall thickness. That is, the recessed portion 3 is formed on the lower surface-side of the outer periphery by using a core in a furan cast die. Hs65 or more of hardness is obtained by applying th case hardening by flame hardening process to the lower surface of the die in the use thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a concrete molding mold used for paving roads, etc.

[Prior Art] The outline of the concrete block molding mold of the present invention is described in the first part.
As shown in the figure. In this mold 1, the following three characteristics are particularly required for the concrete filling part 2.

(1) Fillability (2) Mold releasability (3) Abrasion resistance Materials that meet these characteristics generally have high hardness, are difficult for concrete to adhere to, and have high material strength. Ductile cast iron, which was filed in Japanese Patent Application No. 61-219741, is used.

[Problems to be Solved by the Invention] However, these conventionally used materials were not necessarily satisfactory in terms of durability or wear resistance.

In other words, in nitrided steel, the nitrided layer on the surface is certainly highly wear resistant and has excellent filling and mold release properties, but since the thickness of the coating is several tens of microns at most, the coating is When it wears out, it loses its original properties.

Since the precision of concrete slab L1 is inherently unpredictable at several tens of micrometers, such a precision coating is rather unsuitable for this type of product.

On the other hand, in ordinary cast iron or ordinary ductile cast iron, the presence of graphite affects the filling properties of concrete.

Although it has excellent mold releasability, it essentially lacks wear resistance.

Furthermore, when the molding die is in use, the lower edge portion is particularly abraded and requires wear resistance.

The present invention was made in view of these problems, and its objectives are as follows: (1) Excellent filling properties (2) Excellent mold releasability, wear resistance several times that of conventional cast iron, and superior to nitrided steel. We provide a mold that can be expected to have wear resistance equal to or higher than that of the nitrided layer, the depth of which can be freely changed, and the lower edge of the mold has excellent wear resistance during use. It's about doing.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides that the material of the molding surface is made of spheroidal graphite cast iron, and that the microstructure of the cast iron is a mixture of crystallized graphite and crystallized carbide. It consists of an organization. In addition, in order to improve the wear resistance of the lower edge portion, the thickness of the molded surface is reduced as a casting method in which recesses are formed, thereby making the casting structure finer and increasing the crystallization of carbides. Furthermore, by subjecting the lower surface of the mold to surface hardening using a flame hardening method during use, this mold has a hardness of 65 or more.

Here, if the hardness Hs is less than 65, the wear resistance will be poor, which is not preferable.

[Example] G Si Mn Ni Cr
Mo Hg (%) 3.38 1.91
0,48 1,17 0.36 0,15 0.03
6. Using ductile cast iron with the above composition, a mold for a concrete interlocking block "1" was prototyped under the following manufacturing conditions.The prototype was similar to the mold shown in Figure 1 for explanation, and 40 concrete filling portions 2 are provided.

Manufacturing conditions Mold: As shown in FIG. 2(a), which is a plan view of a mold for forming a concrete block, and FIG. 2(b), which is a cross-sectional view of FIG. 2(a), Using a core, a recess 3 was formed on the lower surface of the outer periphery.

Casting temperature: 1360°C 490 sets Ili: The structure is a mixture of graphite and crystallized carbide, and the area ratio of each is 8% graphite and 30% carbide.

Surface hardening: Flame hardening was performed on the lower surface of the molded surface during use, and the hardness of the hardened surface 4 was 75 to 80 in Shore hardness.

This mold was used on a trial basis to manufacture concrete blocks, and the filling properties, mold releasability, and abrasion resistance of the concrete were tested.

In addition, the filling property is 1! The formability was evaluated by visual observation of the condition of the skin of the concrete block.

Filling properties and mold release properties: No local filling defects or surface roughness were observed on the surface of the finished product.

Wear resistance: Compared to conventional ductile cast iron molds, there was less wear on the mold surface and lower edge, and the number of lifetimes was approximately twice as long.

[Effects of the Invention] As described above, the concrete block molding mold of the present invention has the following effects.

(1) Excellent concrete filling properties and moldability.

(2) Due to less wear, it can withstand approximately twice as much use as conventional products.

(3) It is inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a perspective view for explaining the outline of a mold for molding a concrete block according to the present invention, FIG. FIG. 2(b) is a cross-sectional view taken along line AA in FIG. 2(a). 1... Mold, 2... Concrete filling section, 3...
Recessed portion, 4...quenched surface. = 6-

Claims (1)

[Claims] The material of the molding surface is made of spheroidal graphite cast iron, and the metal structure of the cast iron is a mixture of matrix, graphite, and carbide, and in order to reduce the thickness of the molding surface, a recess is formed on the lower side of the outer periphery. A mold for forming a concrete block, characterized in that the lower surface side of the mold is surface hardened when the mold is in use, so that the hardness of the hardened surface is Hs65 or higher.