RU2002858C1 - Method for centrifugal casting and machine for embodying it - Google Patents

Description

centrifugal acceleration materials and a machine for implementing this method.

The technical result that can be obtained by carrying out the proposed inventions. is the reduction of the crystallization time of the obtained product, thermomechanical loads on the reactors and their lining, as well as dynamic loads on the structural elements of the machine.

The technical result is achieved in that in a centrifugal casting method, comprising preparing an exothermic mixture of powders, placing it in a reaction cavity, initiating a reaction and phase separation of liquid products under centrifugal acceleration, after filling the molds with a heavy phase, it easily drains out, and in a machine for the implementation of this method, comprising a bed with a rotary drive installed on it, a reactor with electrodes in communication with the peripheral casting mold, reactors with casting molds puppies in a saddle mounted with the possibility of swinging in shock absorbers located between the shaft hub and the saddle during its radial rotation, and there are drain holes in the casting molds, and the reactors with casting molds are placed in the casing with unloading devices, and the cavity of the reactor is separated from the casting molds fuses in the gate gates.

The proposed set of features of the claimed object allows to achieve the above technical result in comparison with prototypes. This is due to the following.

Phase separation of liquid products in known reactors that also perform the function of a mold is not complete, because on the surface of the lining in contact with the heavy phase (metallic). often there are films and inclusions of the light phase (containing slag and fluxes). This does not allow homogeneous heavy phase castings to be obtained directly in the reactors. In order to obtain high-quality castings, the liquid products, after some time of standing and phase separation in the reactor, are poured through the sprue holes into the molds. The duration of this melt quenching in the reactor is determined by the thickness of the fusible shutter in the casting hole. Transfusion from the reactor into the casting molds contributes to the additional purification of the melts from inclusions of the other phase and the dissolved gas. The gating openings have a diameter that ensures uniform raising of the level of the liquid heavy phase in the casting mold. When the estimated column height of the solid phase fills the mold, the rest of the melt, consisting of slag, is poured out through the drain holes. Here, it hits the surface of the casing, disperses from impact, cools and brakes upon contact with its surface, and is removed through unloading devices.

The occurrence of an exothermic reaction often leads to significant imbalance5 due to the uneven rate of its occurrence. Elastic mounting of the saddle on the shaft hub, i.e. the possibility of swinging with its radial rotation, allows you to slightly offset the instantaneous axis

& rotations due to unbalancing towards a mass having high centrifugal acceleration. This leads to a reduction in unbalance and dynamic loads on machine parts. The described effect is an analog of the flexible shaft effect known in the art of high rotational speeds.

The drawing shows a centrifugal casting machine according to this method.

0 The centrifugal casting machine contains a bed 1 with a rotary drive 2 installed on it. Reactors 3 with electrodes 4 and peripheral casting molds 5 are located in saddle 6. mounted on

5 of the shaft hub 7 in the shock absorbers 8. The cavities of the reactors 3 are separated from the casting molds 5 by fuses 9 in the sprue holes 10. 8 casting molds 5 have drain holes 11, and reactors 3 with casting molds 5 are placed in the casing 12 with unloading devices windows 13.

A centrifugal casting machine operates as follows.

5 Dry, an exothermic mixture of powders is placed in the reactors 3 and closed by covers 14. Then, reactors 3 with molds 5 are mounted and secured to the seat 6. The machine is accelerated to the required speed and an exothermic reaction is initiated by electrodes 4. The resulting melt of products is pressed against the peripheral ends of the reactors 3, settles, divided into heavy 15

5 and easy 16 phases. After the time required for phase separation, the heavy phase 15 melts the fuses 9 and through the gate openings 10 enters the molds 5, filling them to the required level. The remaining c in reactors 3 is easy

phase 16 entering the molds 5 through the sprue holes 10 is poured through the drain holes 11 onto the surface of the casing 12. The cooled and granulated light phase 16 is removed through the discharge windows 13. The phase 15. crystallized from heavy, having a predetermined shape defined a mold 5 with detachable lining, is removed from it and sent for further processing. After cooling, the linings of the reactors 3 and the molds 5 are cleaned. Fuses 9 are prepared and installed in the gate openings 10. The reactors are again ready for filling with the powder mixture.

An example illustrating this method and the operation of a machine for its implementation is centrifugal casting of nickel borides.

A mixture of powders - a mixture weighing 24 kg. (wt.%): N10 31 (GOST 17607-72). B20z 34 (GOST 6-12-94-78), AI35 (PA-3, GOST 6058-73) are divided equally and put into two reactors installed vertically on a stand. Preliminarily, a conical nickel fusible plug weighing 20 g is installed in the gating holes with a diameter of 3 mm made in a graphite insert and filled with 500 g of CaFa flux covered with asbestos cardboard 1-1.5 mm thick. Reactors made of stainless steel lined with graphite are protected with CaO paint. Molds, also made of stainless steel, are lined from the bottom to the level of the drain holes with a split cast iron chill mold, and in the gap between the gate and drain holes it is similar to reactor.ru.

The charge is ignited simultaneously in both reactors by supplying voltage to the electrodes vibrating with an electromagnet after reaching centrifugal acceleration 120d. The occurrence of an exothermic reaction is observed at the exit from the reactors of hot gases removed by the exhaust system. 20-30 seconds after the initiation of the reaction, liquid slag begins to pour out of the drain holes. After the cessation of slag is stopped, the rotation of the machine continues for 5 minutes. Then the machine is stopped and both reactors are removed for cooling in the scrubbing devices in

within 10 minutes Then the molds and cast iron molds are disassembled, two cast products are removed from nickel borides weighing about 3 kg each and sent for heat treatment. Granular slag, consisting of impurities of B203 weighing about 18 kg, is removed from the collectors and the inner surface of the casing. The use of this slag may be

diverse for example, after grinding to the desired fraction, it is used as an abrasive or as a powder for spraying.

While the reactors are cooled in a scrubber, a second set of reactors and molds, prepared and pre-filled with a charge, is installed on the machine. Thus, the above nickel boride production cycle

lasts about 15 minutes

From the foregoing, it follows that compared with the prototypes of the proposed invention can significantly increase the mass obtained by centrifugal

acceleration of refractory inorganic materials. In this case, dynamic loads arising during the process on the structural elements of the machine, thermomechanical loads on the reactor and foundry

the shapes are significantly reduced, and the lining life of the reactor is increased. Separate hardening of the slag and metal phases reduces the material production cycle time and therefore increases productivity. Granulation of slag facilitates its further use, in particular because its grinding is much simpler than ordinary cast.

Obtaining refractory inorganic materials by the proposed method on a machine for its implementation becomes more productive than the most common method in this technical field

producing materials in the reactor under high gas pressure. The cost of materials obtained using the above method and machine is lower than when using other methods.

(56) Copyright certificate of the USSR No. 617485, cl. C 22 C 29/00, 1978.

USSR copyright certificate No. 186647. cl. B 22 D 13 / 00.1964.

Claims (3)

1. A method for centrifugal casting of refractory inorganic materials, including preparing an exothermic mixture of powders, placing it in a reaction cavity, initiating a reaction and phase separation of liquid products under centrifugal acceleration, characterized in that after separation of the liquid products into phases, the molds are filled with heavy phase, then the light phase is drained out. 2. Machine for centrifugal casting of refractory inorganic materials, containing a bed mounted on rotation drive, a casing with a reactor placed therein with electrodes connected by means of gate openings with peripheral casting molds, characterized in that it is equipped with shock absorbers located on the shaft hub and a saddle in which the reactor with foundry molds having drain holes, and the casing is made with unloading windows. 3. The machine according to claim 2, characterized in that the reactor cavities are separated from the casting molds by fusible closures in the gate openings.