JPH01271054A - Production of casting - Google Patents

Abstract

PURPOSE:To prevent roughening surface on the casting surface even if facing agent is saved by pouring the specific temp. of molten metal into a mold manufactured with binder containing organic binder as main component, developing carbon film having the specific characteristic on interface and casting. CONSTITUTION:The molten metal having 1200-1800 deg.C is poured into the mold with the binder, and by developing the carbon film having the undermentioned characteristic on the interface between the mold and the casting, it is cast. (1) Raman spectrum of the carbon film has bends at 1330-1390cm<-1> and 1550-1630cm<-1> and relative intensity is 0.5-2.0. (2) Face interval in (002) face of carbon with X ray diffraction of the carbon film is 3.35-4.25Angstrom . The relative intensity for two bands is the ratio (B/A) of 1330-1390cm<-1> band height B from the base line to 1550-1630cm<-1> band height A. The organic binder uses fran resin, phenol resin and is desirable to add pitch, tar, etc. By this method, the roughening surface of the casting surface without using heat resistant film on the mold surface, that is, the facing agent, can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a casting manufacturing method for obtaining a smooth casting surface using an uncoated mold. More specifically, the present invention relates to a casting manufacturing method that obtains a smooth casting surface with no or little need for coating by forming a carbon film at the interface between the mold and the casting.

[Conventional technology]

Conventionally, for casting molds, a coating agent is applied after the mold is formed to prevent molten metal from penetrating into the gaps between the sand particles forming the mold and roughening the surface of the casting. Was. These coating agents are applied by methods such as brushing, spraying, and dipping.

[Problem to be solved by the invention]

As for the coating method, - Brushing and spraying are relatively often used for boat fishing, but in both cases it is difficult to make the film thickness of the coating uniform, and brush marks appear on the surface of the casting. Or it may become uneven. Further, this mold coating operation is not preferable from the viewpoint of improving work efficiency, and there is also a problem in that it leads to an increase in mold manufacturing costs.

[Means to solve the problem]

In order to solve the above problems, the present inventors conducted extensive research with the aim of providing a casting manufacturing method that does not require coating molds at all or hardly requires them.
The inventors have discovered that the above-mentioned problems can be solved by forming a carbon film having specific physical properties at the interface between the mold and the cast material during casting, and have completed the present invention.

That is, in the present invention, a molten metal at 1200°C to 1800°C is poured into a mold formed using a binder mainly composed of an organic binder, and a carbon film having the following characteristics is formed at the interface between the mold and the casting. A casting manufacturing method characterized by casting while producing.

(1) The Raman spectrum of the carbon film is 1330-13
It has bands at 90 cm-' and 1550 to 1630 ca+-', and its relative intensity is 0.5 to 2.01, preferably 0.
．． It is 8 to 1.3.

(2) The interplanar spacing of the (002) plane of carbon as determined by X-ray diffraction of the carbon film is 3.35 to 4.25, preferably 3.40 to 3.
．． There are 90 people.

In the present invention, the carbon film having the above-mentioned characteristics formed at the interface between the mold and the casting is a continuous thin layer of partially crystallized carbon, and the formation of such a thin layer achieves the above-mentioned objects of the present invention. is achieved.

In addition, in the present invention, the relative intensity of two bands of the Raman spectroscopic spectrum is 1000 to 1800 as shown in Figure 1.
1330-13 from baseline over cm-'
90cm-' band height (B) 1550-1630
cm-' is the ratio (B/A) to the height (A) of the band.

Raman spectra were measured using a laser Raman spectrum measurement device manufactured by JASCO Corporation, with a laser source of 20-15 mm.
Measurements were made using a 14,5n11 argon laser.

Further, in the present invention, the interplanar spacing of the (002) plane of carbon is a value determined from the diffraction angle of the 002 diffraction line using Black's equation shown in the following equation (1).

2dsinθ−λ ・(1) (In the formula, d is the interplanar spacing, θ is the diffraction angle, and λ is the wavelength of the X-ray.) In the present invention, X-ray diffraction is performed using a thin film X-ray diffraction device (TFD) manufactured by Rigakusha. Measurement was carried out using Cuα rays at an incident angle of 0.2°, a tube voltage of 50 kV, and a tube current of 100+*A.

The organic binder used in the present invention is furan resin, phenol resin, etc., but it is possible to use an inert gas, For example, when rapidly heated to 1000-1050°C in a helium gas atmosphere, benzene, toluene, ethylbenzene, ethyltoluene, etc.
Organic binders that generate a large amount of aromatic compounds substituted with methyl groups or ethyl groups, such as xylene, cresol, and xylenol, are preferred.

It is also preferable to add pitch, tar, etc., although they do not contribute to the curing reaction. The amount of organic binder added is 1
0.5 to 6 parts by weight per 00 parts by weight of refractory granular material are preferred.

Furthermore, methods for curing the organic binder include self-hardening and gas-hardening cold boxes. As the hardening agent for the self-hardening mold method, organic sulfonic acids such as para-toluenesulfonic acid and xylene sulfonic acid, inorganic acids such as phosphoric acid and sulfuric acid, and mixtures thereof are used. In addition, peroxides for the acid-curing cold box method include ketones,
Organic peroxides such as aromatic ones and inorganic peroxides such as hydrogen peroxide are used. The amount of these curing agents and peroxides added is preferably 10 to 70 parts by weight per 100 parts by weight of the organic binder.

As the refractory granular material constituting the mold used in the present invention, silica sand containing quartz as a main component, zircon sand, chromite sand, etc. are used.

In addition, in order to provide functions other than the purpose of obtaining smoothness of castings, sulfurization inhibitors such as Mg'O and CaC0a are used, and various known agents such as γ-aminopropyltrimethoxysilane are used to improve mold strength. It is also possible to mix additives into the mold, such as silane coupling agents.

Furthermore, conventional methods of manufacturing molds and castings have been developed in which the structure of the mold is divided into a skin sand part that comes into contact with the molten metal and a back sand part inside the mold, and fine-grained refractory aggregate is used for the skin sand, and the mold coating process is omitted. Although it is known, by forming a carbon film on this skin sand in the present invention, it is also possible to further improve the smoothness of the casting surface.
It also allows the use of coarser aggregates. In the present invention, the mold containing a relatively large amount of carbon source formed as described above is heated at 1200 to 1800°.
It is thought that the heat generated when pouring the molten C decomposes the carbon source, and a partially activated crystallized carbon film is generated at the interface between the mold and the casting.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited only to these Examples. Furthermore, in Examples and Comparative Examples, "parts" are all parts by weight.

Example 1 39 parts of furfuryl alcohol, 49 parts of glycidyl ether of 0-talesol novolak (Sumi Epoxy ESCN-220-10J manufactured by Sumitomo Chemical) and 1°2.4-
11 parts of trimellitic acid triallyl ester was added and dissolved to obtain an organic binder.

To 100 parts by weight of foundry sand (flattery sand), 2 parts of the above organic binder and 0.2 part of 60% xylene sulfonic acid were stirred for 2 minutes to produce a mold.

A 1350°C molten metal (equivalent to FC-20) was poured into this mold, and the surface roughness of the casting obtained was measured, and the formed carbon film was analyzed.

The results are shown in Table-1. In addition, the surface roughness of each part of the casting 1
The center line average roughness (Ra) of the four points was averaged.

Example 2 A mold was produced in the same manner as in Example 1, except that a solution of 20 parts of acenaphthylene added to 80 parts of furfuryl alcohol was used as the organic binder, and casting was performed in the same manner as in Example 1. I got a casting.

Measurement of the surface roughness of the obtained casting and analysis of the carbon film were carried out in the same manner as in Example 1.

The results are shown in Table-1.

Example 3 Glycidyl ether of 0-talesol novolak ("Sumiepoxy ESCN-2" manufactured by Sumitomo Chemical ■) was added to 39 parts of xylene.
20-10'') and 11 parts of 1,2.4-trimellitic acid triallyl ester were added and dissolved and used as an organic binder, and 0.0% of cumene hydroperoxide was added instead of 60%-xylene sulfonic acid. Using 3 parts, S
A mold was manufactured in the same manner as in Example 1 except for gassing O□ gas, and casting was performed in the same manner as in Example 1 to obtain a casting.

The surface roughness measurement of the obtained casting and the analysis of the carbon film were carried out in the same manner as in Example 1.

The results are shown in Table-1.

Comparative Examples 1 and 2 1.2 parts of general furan resin (R340B manufactured by Kao Acre Mari) was added to 100 parts by weight of foundry sand (flattery sand).
In Comparative Example 1, a mold was prepared in the same manner as in Example 1 except that 0.48 part of 60%-xylene sulfonic acid was used as the organic binder. As Example 2, casting was performed in the same manner as in Example 1 to obtain a casting.

The surface roughness of the obtained casting was measured in the same manner as in Example 1.

The results are shown in Table-1.

Note that in Comparative Examples 1 and 2, no carbon film was formed.

Table 1 [Effects of the Invention] Conventionally, a heat-resistant film, that is, a coating mold, was applied to the surface of the mold to prevent molten metal from penetrating into the gaps between the sand particles forming the mold or fusion with mold components such as aggregate. This prevents the casting surface from becoming rough due to adhesion.

However, according to the present invention, roughening of the surface of the casting can be prevented or improved even if the coating mold is completely or almost completely omitted, and the casting process can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a Raman spectrogram of a carbon film. Applicant's agent Kaoru Furutani Figure 1 Number of waves (return)

Claims (1)

[Claims] 1. Molten metal at 1200°C to 1800°C is poured into a mold made with a binder mainly composed of an organic binder, and a carbon film having the following characteristics is formed at the interface between the mold and the casting. A casting manufacturing method characterized by casting while producing. (1) The Raman spectrum of the carbon film is 1330-13
It has bands at 90 cm^-^1 and 1550 to 1630 cm^-^1, and their relative intensities are 0.5 to 2.0. (2) The interplanar spacing of the (002) plane of carbon as determined by X-ray diffraction of the carbon film is 3.35 to 4.25 Å. 2. Raman spectrum of carbon film 1330-139
The manufacturing method according to claim 1, wherein the relative intensity of each band of 0 cm^-^1 and 1550 to 1630 cm^-^1 is 0.8 to 1.3.