RU2470733C1 - Method of rounding aluminium alloy castings - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy. Prior to pouring of melt, special coating is applied at billet points to be rounded. Said coating consists of solution of magnesium oxide powder with mean particle size not exceeding 0.1 mm and industrial oil. Thickness of applied coating layer of the solution makes 0.05-0.1 mm of rounding radius.

EFFECT: rounding radius of 1 to 12 mm.

Description

The invention relates to foundry and can be used for the manufacture of small and medium-sized cast products (cases, plates, plates with rounded edges, rings, etc.) based on aluminum alloys with a melting point of 400-700 ° C.

A known method and device for increasing the strength of crankshafts (ROYSS Cornelius. Method and device for increasing the strength of crankshafts. Application for invention No. 2009119525. Publish. 11.27.2010). The method of hardening the run-in of the crankshaft fillets includes the steps of:

provide one rolling element for applying one force to the workpiece;

provide one support element for supporting the workpiece against the force exerted by the rolling element;

move one rolling element and / or at least one supporting element so that one supporting element and / or one rolling element move relative to each other and / or relative to the workpiece, that said movement contains a linear component.

The disadvantages of the method include the fact that it can only improve the quality of existing rounds and fillets, not allowing you to create new ones. The method requires additional technological equipment, which also leads to an increase in the cost of using this technology.

A known method of processing fillets of a stepped shaft (Goncharov I.T. Method of processing fillets of a stepped shaft. RF patent No. 2368487. First of all, the fillet is machined with a thrust cutter with a radius at the apex of 0.2-1.0 mm and its subsequent cold plastic deformation by a roller with a profile radius r = 0.01-0.03d, where d is the shaft diameter in the fillet zone. In this case, cold plastic deformation is carried out to a depth of t = 0.2r ± 0.05 mm.

The disadvantages of the method include the fact that the method for producing fillets and rounding requires the manufacture of a special tool - a cutter with an angle at the apex of 0.2-1.0 mm. This leads to additional costs for the manufacture of the part. In addition, this method relates to the manufacture of fillets only on shafts.

Closest to the claimed method is a method of obtaining fillets at the corners of parts by turning with a special shaped cutting tool (A.A. Panov, V.V. Anikin and others. Metal processing by cutting. Handbook of the technologist. - M .: Engineering. - 2004). The method allows to obtain fillets of any radius by cutting the metal layer of the workpiece with a specially designed tool. To obtain a rounding, the workpiece is machined with a special shaped cutter or shaped cutter. The tool cuts off the excess metal layer, forming fillets on the side faces of the workpieces.

The disadvantages of this method include the need to create a special cutting tool, which leads to a significant increase in the cost of the part in the case of single and small-scale production. In addition, additional time is spent on processing with this tool, which leads to a decrease in the output of finished products per unit time.

The objective of the proposed technical solution is the formation of fillets on the necessary faces of the workpieces during casting of aluminum alloys with a melting point of 400-700 ° C.

To achieve the technical result, a coating is applied to the angular surface of the mold. The coating consists of a solution of magnesium oxide powder of 15-20% with an average particle size of not more than 0.1 mm in 80-85% of industrial oil. The thickness of the coating is 0.05-0.1 of the radius of the rounding of the casting. In this way, it is possible to obtain castings with roundings within 1-12 mm.

A powder solution in industrial oil is prepared immediately before applying it to the working surface of the mold. The composition of the solution includes 80-85% of industrial oil and 15-20% of magnesium oxide powder. This ratio of components is explained by the fact that with a larger amount of oil in the coating it will not have sufficient viscosity and will drain from the surface to be coated, and with less oil, the coating will be more dense in composition and will not ensure uniform coating on the walls of the mold. Figure 1 shows the scheme of applying a special coating before pouring the melt. Before pouring the melt 4, the coating 2 is applied to the working surface of the mold 3 in the area where the casting will not come into contact with the mold due to the formed rounding 1. The thickness of the applied layer of the solution is 0.05-0.1 mm from the radius of the obtained rounding. The method allows to obtain fillets with a radius of 1 to 12 mm.

The essence of the invention is as follows: the coating layer applied to the surface of the mold in contact with the melt is partially gasified, forming an air mixture of magnesium oxide particles and gases. Magnesium oxide particles do not interact with molten aluminum alloy and, having a higher melting point, will not soften. A particle size of less than 0.1 mm will allow the particles not to deposit on the walls of the mold all the time of crystallization, forming a suspension of particles in the formed gases. This mixture prevents contact of the metal with the mold in the applied area and forms fillets on the castings after hardening. Figure 2 and figure 3 shows the appearance of the fillets obtained in the described manner on castings from silumin. Figure 2 shows the face of the casting with rounding with a radius of 5 mm, figure 3 shows the face of the casting with a radius of 8 mm

The application of this method allows to reduce the cost of parts by reducing the amount of machining to obtain fillets by machining with a shaped tool. The costs of designing, manufacturing and using a special cutting tool - shaped cutter are excluded.

Example 1

On the corner surface of the mold, where it is necessary to obtain a rounding with a radius of 5 mm, a coating layer is applied. The coating consists of industrial oil in an amount of 82% and 18% of magnesium oxide powder with an average particle size of 0.08 mm. The thickness of the coating layer is 0.3 mm. AK12 grade silumin is poured into the mold. As a result, after the casting has hardened, a rounding with a radius of 5 mm is formed in the corner obtained by joining two faces (see FIG. 2).

Example 2

A coating layer is applied to the corner surface of the mold where it is necessary to obtain a rounding with a radius of 8 mm. The coating consists of industrial oil in an amount of 84% and 16% of magnesium oxide powder with an average particle size of 0.09 mm. The thickness of the coating layer is 0.5 mm. AK12 grade silumin is poured into the mold. As a result, after the casting solidified, a rounding with a radius of 8 mm was formed at the junction of the two faces (see Fig. 3).

Claims (1)

A method for producing fillets on aluminum alloy castings, characterized in that a coating consisting of a solution of magnesium oxide powder of 15-20% with an average particle size of not more than 0.1 mm and 80-85% of industrial oil is applied to the corner surfaces of the mold this coating thickness is 0.05-0.1 of the radius of the fillet roundings of 1-12 mm.

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