JPH01284456A - Method of carburizing steel product - Google Patents

Abstract

PURPOSE:To shorten the tie for a carburizing operation without requiring a carburizing device and a carburizing agent by forming a mold coat by a mold coating liquid to the outside of foamed polystyrene, thereby constituting a specific expandable pattern. CONSTITUTION:The pattern 3 is formed of the formed polystyrene having at least 0.8 pond per square foot in density and the mold coating liquid having at least >=45Be concn. is used for the mold coat 4 to be coated on the outside thereof. A molten steel or steel alloy 8 passes a runner 5 through a sprue and arrives at the pattern 3 to gasify and expend the pattern 3 when the molten steel or steel alloy 8 is supplied to the sprue. The gas generated on the expenditure of the pattern 3 passes the layer of the mold coat 4 and emerges to the upper part of a flask 1 by passing the spacings of a packing material 2. However, a part of the gaseous hydrocarbon stays on the inner side of the mold coat 4 and exerts influence to the cast product. The carbon in said gas in particular penetrates to the inner side of the cast product in the mold and the carburization is effected upon lapse of time. Since the time for removing the mold coat 4 from the cast product after the casting is at least 5 minutes and, therefore, the carburized layer of at least 0.5mm depth from the outside surface of the product is obtd. by the carbon in the gas.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for carburizing W4 products used in the manufacture of various steel products such as various tools, gears, shafts, crankshafts, etc.

Conventional technology Various methods have been used to carburize prepared products. For example, in the solid carburizing method, the prepared product is first placed in a copper carburizing box and surrounded by charcoal, coke, etc. Packed with carburizing agent and accelerator such as soda carbonate, covered with a steel lid, sealed with clay, and heated in a furnace for 800 min.
Heating at ~900℃ for several hours, then cooling, then quenching,
Perform tempering.

Problems to be Solved by the Invention However, the conventional method requires expensive carburizing equipment including a furnace, requires a carburizing agent, requires energy to heat the product, and takes a long time.

This invention was made to solve such problems, and its purpose is to eliminate the need for a carburizing device like the conventional carburizing equipment, and to eliminate the need to use a carburizing agent like the conventional carburizing agent. It is an object of the present invention to provide a method for carburizing steel products that does not require energy for heating the product and does not require a long time for the above-mentioned operations.

Means for Solving the Problems According to the present invention, the density is at least 0.
A coating mold is formed on the outside of the styrofoam model of 8 Bond Birth Care Feet with a coating liquid with a concentration of at least 4513e to form a vanishing model, and the model is filled in a flask with 1 volume of non-flammable filling. A runner having a sprue is connected to the model, molten water or steel alloy is supplied from the sprue to cast the product, the product is taken out from the filling material, and the product is cast. A method for carburizing steel products, characterized in that the coated product is removed from the coated product after at least 5 minutes, and a carburized layer reaching a depth of at least 0.5 txm IIC from the outer surface of the cast product is formed on the cast product. .

When molten steel or steel alloy (hereinafter simply referred to as hot water) is supplied to the sprue, the hot water passes through the sprue and reaches the model, gasifies the model and disappears, and enters the space created there. Casting is then carried out. The gas generated as the model disappears passes through the layer of the coating mold and exits to the top of the flask through the gaps in the filling, but some of the gas does not pass through the layer of the coating mold. , stays inside the coating mold. This gas is a hydrocarbon gas, and since it is present between the coating mold and the cast product, it affects the cast product, especially the carbon in the gas over time! It penetrates into the inside of the iJJ manufactured product and carburization is performed there. In this case, the expanded polystyrene of the model has a density of at least 0.8 bond base care feet, and the coating mold is formed from a coating liquid having a concentration of at least 4513e or higher, and Since the time for removing the coating from the cast product is at least 5 minutes, the carbon traps in the gas form a carburized layer of at least 0.5 tram depth from the outer surface of the product.

Embodiment The inventor of the present invention has previously devised and disclosed a casting apparatus as shown in Figure 1. (Utility model registration application No. 49276, 1986).

Since this invention can be carried out using the device of the above-disclosed invention, a case where the same device is used will be described as an example. Of course, other known and conventionally used devices may also be used.

In Figure 111, 1 is an iron flask, 2 is sand as a filler, and 3 is a model made of expanded polystyrene, which is formed into a bond base foot with a density of at least 0.8. 4 is a coating mold, the raw material of which is usually imported, and is generally a mixture of fine powder of silica, feldspar, quartz, alumina, etc. with water, alcohol, precision, etc., and has a low concentration. Both are 4513e or higher. By coating this raw material liquid on the outer surface of the model 3 and drying it, a coating mold 4 consisting of a layer of breathable and fire-resistant fine mineral particles is formed on the outer surface of the model 3. 5 is a runner, and the runner 5 is made of expanded polystyrene. 6 is the sprue, 7 is the furnace, 8 is the hot water, 9 is the small hole 10
1 indicates the ignition device, and 12 indicates the flame. The hot water 8 passes through the runner 5 after being dissolved and gasified, reaches the model 3, where it is gasified and dissipated and replaced as shown in Figure 2, forming the casting product 3.0 The generated gas is removed. The gas 9 enters through the small hole 10, rises, and is ignited by the ignition device 11 at the upper end of the gas 9 to burn. As time passes, the product 13 changes from its outer surface 14.
Carbon generated by the decomposition of the gas penetrates into the inside of the product 13, and carburization is performed. The depth of carburization is proportional to the foam density of the expanded polystyrene of the model 3 and the concentration of the coating liquid, and is also proportional to the time until the coating mold 4 is removed from the product 13.

Figures 1 and 3 show products with a carburized layer 15 obtained after removing the coating mold 4. In Figures 1 to 3, the layer of the coating mold 4, the carburized layer 15, etc. are easily understood. It is exaggerated to make it more accurate.

Next, the graph shown in Figure 114 shows the data of the experiment of this invention. There were two types of models 3 used in the experiment, A and B. Model A had a foaming density of styrofoam of 2. 5
Model B is a 0.9 bond perspective care foot, each with a diameter of 25 pigeons and a length of 2.
00 m in the shape of a round bar, each with a runner 5 made of foamed polystyrene, and each model A, 13 has a
A coating liquid with a concentration of Be or higher is applied and formed, and after drying, it is embedded in a dry sand filler 2 stored in a flask 1, and vibration is applied to make the filler 2 dense, and 815C material is placed in the runner 5. I poured hot water.

After pouring, the product 13 is taken out from the flask 1, and the coating mold 4 is broken immediately after the product 13 is taken out.

After removal and cooling, the carburization depth of each product was measured, and the carburization depth was 3.5 m for the model A product and 1.51 m for the model B product. (See Figure 4) Note that the cooling described above omits the use of a baking iron furnace.

Next, as another example, By was formed on models similar to the above-mentioned models A and B, and cast products were formed using 815C material, and each product was taken out of the flask 1 and the coating mold 4 was removed. The time required for each test was 15 minutes. As a result, the depth of the deep coal layer 15 according to model N was 2.8 mm. Furthermore, the depth of the deep coal layer 15 according to model B was 0.8 fins.

The graphs shown in Figures 3 and 4 were obtained through each of the above experiments.

Although a detailed explanation will be omitted, an experiment was carried out using a model of a bond bathe foot with a foaming density of 0.8 according to the method described above in accordance with the present invention. This also provided a deep coal seam deep enough for practical use. The practical limit of the depth of the deep coal layer is 0.51fi+, which is the limit of carburization that is generally carried out, and has a value higher than that.

The depth of the carburized layer can be adjusted by changing the foam density of the styrofoam. In other words, when the foaming density is lowered, the carburized layer becomes shallower, and the carburized layer becomes shallower (the carburized layer becomes deeper).

The carburizing depth can also be adjusted by adjusting the so-called break-up time, in which the product is removed from the flask and the coated mold is removed. In other words, by speeding up the disassembly time.

The carburizing depth can be made deeper by increasing the concentration of the coating liquid, and shallower by decreasing it. .

Effects of the Invention The present invention is constructed as described above, and a coating mold is formed on the outside of a foamed polystyrene model having a foaming density of at least 0.8 pounds with a coating liquid having a concentration of at least 45Be. , the mold is used to supply and cast molten scrap or steel alloy, the coating is removed from the product at least 5 minutes after casting, and the product is coated to a depth of at least 0.5 mm from the outer surface of the product. By forming a carburized layer reaching 5 shoulders, there is no need for a carburizing device as described in the conventional example, there is no need to use a carburizing agent as in the conventional example, and the energy required for casting is used. To provide a method for carburizing steel products that does not require energy for heating the product as described in the conventional example, and does not require a long time to work as described in the conventional example. I can do it.

Furthermore, product manufacturing and carburizing can be done at the same time.

[Brief explanation of the drawing]

Figures 1.1 to 2.3 show embodiments of this invention, and 1.1
Figures 1 and 4 are graphs showing the experimental results of the method of the present invention. 1...Flask 2...Filling material 3...Model 4...Coating mold 5...Run runner 8...Melted steel or steel alloy 13...Product 15...Carburized layer

Claims (1)

[Claims] A vanishing model was constructed by forming a coating mold with a coating liquid having a concentration of at least 45Be on the outside of a Styrofoam model having a density of at least 0.8 pounds per care foot, and the model was placed in a flask. The product is buried in a non-combustible filling, a runner with a sprue is connected to the model, molten steel or steel alloy is supplied from the sprue to cast the product, and the product is taken out from the filling. . A method for carburizing steel products, characterized in that the coating mold is removed at least 5 minutes after casting the product, and a carburized layer reaching a depth of at least 0.5 mm from the outer surface of the product is formed on the product.