Technology for manufacturing a cast "Cheek" weighing 80 kilograms from steel 25 L - course

Introduction

Any machine or product consists of separate parts made of various materials and made by certain methods (casting, forging, stamping, machining, etc.)

Among the methods of manufacturing parts, casting occupies a leading place, somewhat inferior in recent years to welding. The share of cast parts in the design of modern machines varies widely from 25 to 80%, averaging about 40%.

Cast parts are characterized by a very wide variety in weight and size.

They are made from various alloys, materials, including plastics. Casting methods can be used in a wide variety of ways depending on the requirements for the quality of parts, their serial production.

There are six groups of complexity of castings, which imposes a certain imprint on the manufacture of the part. Simple parts can be made without rods, and the most complex are practically made of rods (up to 40 rods per cast).

The design of the part is developed by the designer of the machine or mechanism, and he at least thinks about the method by which the part will be manufactured and, of course, does not take into account the peculiarities of the casting technology. Therefore, up to 80% of the parts are then finalized by engineers, including foundries. Their efforts are reduced to increasing the processability of the part (reducing mass, energy consumption, reducing scrap).

1 Development of mold and casting elements

1.1 General Constructability Analysis

The working conditions of the part are of paramount importance for its design and the choice of material from which the part will be made.

This "Cheek" part is used to secure movable mechanisms in the crushing plant. There are holes that will be made by rods.

There are some slopes that meet the casting requirements. The part does not require technological changes and additions to the design; it can be manufactured by casting.

1.2 Selection of casting material

Obviously, the method of making the part by casting is the optimal solution of the manufacturing method. The casting material is specified by the customer, so the work did not make a material selection using the comparison method.

1.12 Substantiation of drying of molds

The use of drying always impairs the technical and economic performance of production. The reason for this is an increase in the cost of manufacturing the mold (about twice), a significant fuel consumption for drying and deterioration of the technological process in the workshop.

When designing the casting technology, it is always necessary to strive to use raw molding. Dry moulds for the manufacture of castings are used only in the presence of the following factors:

- in the manufacture of large and complex castings of individual and small-scale production. In this case, the assembly of the molds usually takes a long time, which leads to the showering of the molds;

- when pouring high molds, with a height of more than 600-700 mm (drying is necessary to strengthen them);

- When refrigerators are used, when moisture condenses, which can lead to the marriage of castings to gas sinks.

For steel casting, in order to reduce the gasification capacity of the mold, it is necessary to dry the mold. Considering the serial production, drying of the mold will be carried out using infrared driers of the pass type. This dryer will be located above the conveyor belt on which the molds will move. Passing the mold through this dryer will provide sufficient drying of the molding mixture.

1.13 Development of technology for assembly and pouring of molds, cooling, knocking out, cutting and cleaning of castings

Mold assembly is carried out on the casting conveyor, and consists in the installation and attachment of rods, thorough cleaning of the mold cavity from dust and the remains of the moulding (rod) mixture, control of the wall thickness of the future casting, implementation of measures to prevent the melt from flowing into the ventilation system and leaking it through the connector line, covering the upper half-mold with the lower one, installation of gate and discharge bowls, fastening of the half-molds. The duration of storage of raw forms collected for pouring must not exceed one hour.

We will fasten with braces. Metal is poured from a 1 ton bucket at a temperature of 1540-15500 C. The filling time of each mold is 24.7 seconds, and the cooling time according to Table 8.1 of the source [3] 3.4... 5.3 hours.

The casting is knocked out of shape on an impact inertial grille. The knocked out moulding mixture is transferred to the mixing compartment for regeneration. We knock out the rods on the cleaning drum.

After the casting is knocked out, the casting is cleaned to remove possible burning and residues of the forming and rod mixture. For a given casting, a cleaning drum of the IZM type is applicable, where cleaning is carried out by fraction.

On the cut section of the casting, we remove the remains of the elements of the sprue system and the bays along the outline of the rod signs and the shape connector, as well as all surface roughness. Chopping is carried out with a pneumatic hammer or on a specialized complex with a conductor for individual casting. For grinding we use a grinding machine.

Cleaned castings are subjected to heat treatment - tempering or normalization. Since the casting is prone to the formation of large internal stresses, tempering is chosen as the heat treatment. Heat to 6200 С at a rate of 800 С/h, hold for 3 hour at this temperature and cool at a rate of 500 С/h to 2500 С.

Drawings of model plates and molds assembled are shown in Appendix.

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