RU2015791C1 - Method for manufacturing ferromagnetic moulds - Google Patents

Abstract

FIELD: moulding. SUBSTANCE: method involves filling of moulding box 1 with model set 2 by preliminary magnetized ferromagnetic moulding material 5 and further subjecting it to a variable magnetic field moving along the axis of the moulding box and to additional mechanical effect which begins later and is accomplished earlier than the beginning and the end of magnetic field effect respectively. EFFECT: improved quality. 1 dwg

Description

 The invention relates to foundry, in particular to the manufacture of molds from ferromagnetic materials, mainly magnetically solid.

 The purpose of the invention is to improve the quality of molds by increasing the degree of compaction of the molding material in the flask, increasing process productivity and reducing energy consumption by reducing the molding cycle time.

 The method is as follows. In the manufacture of molds from ferromagnetic materials, mainly magnetically solid, fill the flasks with a model set with pre-magnetized ferromagnetic material and compact it by exposing it to an alternating magnetic field moving along the flask axis. The molding material in the flask is further compacted by mechanical action. Moreover, the mechanical effect begins later than the beginning of the magnetic field, and ends before the end of the magnetic field.

 The drawing shows a schematic device for implementing the method.

 The flask 1 with model kit 2, placed on the table 3 of the lifting device 4, is filled with a pre-magnetized ferromagnetic molding material 5. The supply of molding material 5 for subsequent compaction is provided by the float tank 6.

 When applying an alternating voltage to the electromagnet 7, an alternating magnetic field is created, which, interacting with the molding material in the flask, brings it into a pseudo-fluid state. In this case, the molding material is evenly distributed over the volume of the flask, individual clumps are disintegrating, the material fills voids, narrow grooves, model cavities and is compacted. For an additional mechanical sealing effect, press pad 8 is used.

 Simultaneously with the inclusion of the electromagnet 7 or with a slight delay in time, the drive of the lifting device 4 is turned on and the flask 1 moves upward, passing through the hole of the electromagnet 7. In this case, the press pad 8, interacting with the molding material 5, forces it out of the flask storage 6 into the flask 1 and further compacts it.

 Due to the fact that after the beginning of the lifting of the flask 1, a certain distance passes before the surface of the press pad 8 begins to interact with the molding material 5, the onset of mechanical action on the molding material is ensured later than the beginning of exposure to the electromagnetic field.

 The premature onset of mechanical action makes it difficult to transfer the molding material 5 to a pseudo-fluid state, which negatively affects the uniformity of filling of the flask 1.

 Upon reaching the desired degree of compaction, as evidenced by the sharply increased effort on the lifting device 4, mechanical stresses are completed by turning off the lifting device 4, and the electromagnet 7 is turned off a little later. During this period of time, the magnetic field prevents the appearance of cracks in the compacted molding material 5, which usually occur during mechanical compaction without the influence of a magnetic field and lead to the destruction of the molds when removing models from them.

 Thus, according to the proposed method, the molding process occurs in one stroke of the flask 1 up. The inventive method was carried out on a resonance induction molding device, made according to the scheme shown in the drawing. As a ferromagnetic molding material, a hard magnetic metal powder was used according to TU 609-27-201-86 with a grain size of 0.05-1.0 mm. The flask and superficial storage are made of non-magnetic material (aluminum alloy) in the form of frames 200 mm high and 600 x 300 mm clear. The press block, the table of the lifting device and the model plate are made of dielectric (textolite).

The electromechanical type lifting device comprises an electric motor, a worm gear and a cargo screw pair. The maximum force on the screw is 13-10 ⁴ N, the table lifting speed is 1.5-2.0 cm / s.

 The electromagnet is made in the form of a coil with a height of 500 mm / s, an opening of 800x500 mm in size for passing the flask. The voltage of the electromagnet is 350 ± 5 V, the current consumption is 200 ± 30 V, the power consumption is 100 ± 30 kW.

 The model kit, mounted on the table of the lifting device, consisting of a flask, a flotation tank, a model plate and a model, was filled with molding powder to the upper plane of the flotation tank. The surface of the powder is leveled without tamping.

 The press block was fixed above the surface of the powder at a distance of 15. ..20 mm. When applying voltage to the electromagnet and turning on the drive of the lifting device, a molding process took place. The required degree of powder compaction during the molding process was controlled indirectly by the force on the drive of the lifting device, to which the drive clutch was adjusted. When it is activated, the lifting device is automatically turned off. After the molding process and model extraction, the degree of compaction of the powder was determined by measuring the hardness of the surface of the powder at several points. Then the form was destroyed to determine the uniformity of compaction of the powder in the volume of the flask and the quality of filling the flask. The quality of the mold was determined with a different sequence of effects on the molding material of the magnetic field and mechanical stress.

 The results of these experiments are shown in table 1.

 The quantitative characteristics of the molding process are also determined at the recommended sequence of operations, when the mechanical action begins later than the beginning and ends earlier than the end of the magnetic field.

 The results of these measurements in comparison with the known method (prototype) are given in table.2.

 Using this method can improve the quality of molds made of ferromagnetic materials, and, therefore, casting by increasing the degree of compaction of the molding material. Reducing the molding cycle time by compacting the molding material in a single flask stroke in a magnetic field can increase molding productivity and reduce energy consumption.

Claims (1)

 METHOD FOR PRODUCING CASTING FORMS FROM FERROMAGNETIC MATERIALS, mainly magnetically solid, which consists in filling the flask with a model kit with a pre-magnetized ferromagnetic molding material and then exposing it to an alternating magnetic field moving along the flask axis, characterized in that, in order to improve the quality of castings sealing molding material, increasing productivity and reducing energy consumption by reducing mold cycle times wakes, the molding material located in the flask is additionally compacted with compressive mechanical action, providing the beginning of mechanical action on the material later, and the end earlier than the beginning and end of the magnetic field, respectively.

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