RU2562188C2 - Device to produce casts by directed crystallisation - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy. Device comprises melting chamber 1 with melting-teeming unit arranged at post 8 and filling cone 25, mould 19 heating chamber 2 with inductor 21 arranged outside the chamber and chamber 10 for loading of mould 19. Melting and heating chambers are composed of cylindrical quartz tubes with water-cooled metal spacer 3 arranged between the ends of said tubes and provided with holes for connection with vacuum system. Melting-teeming unit and filling cone 25 support are arranged at spacer 3. Vacuum gate 9 is located between heating chamber and mould loading chamber. Mould is fitted on rod 14 equipped with the mould vertical displacement drive. Central bore is made in said rod to feed cooling inert gas to mould bed.

EFFECT: higher reliability of device operation and quality of casts.

3 cl, 4 dwg, 1 ex

Description

The invention relates to the field of foundry and can be used to produce castings directed by crystallization from steels and nickel alloys.

Induction melting or thermal furnaces are known in which the vacuum chamber is made of a heat-resistant vacuum-tight quartz tube. A quartz pipe is sealed through elastic gaskets with steel caps attached to the ends of the pipe. Holes are made in the covers for evacuating the furnace chamber, loading products, and installing control devices. Concentric to the quartz tube, an inductor is installed outside. A melting ceramic crucible or an electrically conductive heater is installed inside the pipe at the inductor level, the heater is insulated from the quartz pipe by ceramic thermal insulators or metal shields [M. Leykand Vacuum electric furnaces. - M.: Mechanical Engineering, 1977, p. 17-18; ALD website, http://web.ald-vt.de/cms/vakuum-technologie/anlagen/iwq/].

Analogs have a small volume of the vacuum chamber, which ensures a reduction in energy consumption for the set and maintenance of the working vacuum and allows for fast heating of products to high temperatures by creating high specific energy capacities inside the quartz tube.

The disadvantage of analogues is the inability to implement in them directed crystallization of a metal with a uniaxial structure.

A device for the manufacture of castings by directional crystallization, containing a vacuum chamber, which houses a melting and casting unit with a crucible and an inductor, a block of a heating furnace with an induction or resistance heater, a loading chamber, a mold located on a rod equipped with a vertical movement mechanism [http: / /web.ald-vt.ru/cms/fileadmin/pdf/prospekte/vim_ic_eng.pdf, p. 3].

After pouring, the mold is withdrawn from the heating furnace to the loading chamber at a given speed, resulting in directional crystallization of the molten metal with orientation of the structure, the removal of pores in the upper part of the casting and obtaining non-porous castings with a uniaxial structure.

The disadvantages of the analogue include the large dimensions of the vacuum chamber, which determine the increased energy consumption for the set, the provision of vacuum and cooling the chamber during the entire process of casting.

A device for the manufacture of castings by directional crystallization (prototype), comprising a vacuum chamber with a sliding cover, a lock chamber for loading a mold with a rotary cover, guides mounted in vacuum and lock chambers, carriages placed on them with suspensions for securing the molds with horizontal and vertical movement of forms. Inside the vacuum chamber there are foundry mold heating furnaces with resistance heaters, heat-insulating screens. In the vacuum chamber there is also an induction furnace for melting and pouring metal, a container with a liquid metal cooler. The device is equipped with a lock chamber for loading a metal charge into a crucible of a melting furnace [patent RU 2267380 C1, 01/10/2006].

The disadvantages of the prototype are:

1. The large dimensions and volume of the vacuum chamber determine the increased energy consumption for the set and maintenance of the working vacuum, as well as the need for a complex system of water cooling of the chamber casing.

2. The fragility of the resistance heaters of the heating furnace at operating temperatures.

3. The need to place the mold on the suspension for immersion in a liquid metal cooler. With large masses of castings, fragile and brittle ceramic forms often come off and fall into the liquid metal cooler with negative consequences (casting defective, failure of the cooler, heating furnace and vacuum chamber).

The objective of the technical solution is to reduce energy consumption and increase the reliability of the device by reducing the volume of the vacuum chamber and increasing the specific power in the heating furnace.

The problem is solved in that in a device for producing castings with directional crystallization, containing a melting chamber, in which a rotary melting and casting block consisting of a crucible and an inductor is placed on the axis, a mold heating chamber, in which a heating block consisting of an inductor is located, placed outside the chamber, the heat insulator and the electrically conductive heater, arranged concentrically, the mold loading chamber, and the mold mounted on a rod equipped with a vertical mechanism movement of the mold, a vacuum shutter located between the heating chamber and the mold loading chamber, a casting funnel placed on a support mounted on a spacer, according to the invention, the melting chamber and the heating chamber are made of cylindrical quartz pipes, between the ends of which there is a water-cooled metal spacer, having a hole for connection to a vacuum system, the melting and casting unit is placed on the rack, while the rack and the support of the casting funnel are placed on the spacer, and in a central hole for supplying an inert gas to the base of the mold is made.

In the device for producing castings by directional crystallization, the spacer can be made of chromium-nickel steel.

In the device for producing castings with directional crystallization, an annular water-cooled metal adapter can be installed between the chamber of the heating furnace and the vacuum shutter.

The technical solution allows to reduce energy consumption and increase the reliability of the device by reducing the volume of the vacuum chamber and increasing the specific power in the heating furnace.

The technical nature of the proposed technical solution is illustrated by drawings, in which:

FIG. 1 is a diagram of a device;

FIG. 2 is a view “A” in FIG. one;

FIG. 3 - casting "ball plug" of steel 12X18H10T;

FIG. 4 - section of the casting "ball plug" of steel 12X18H10T.

The proposed device (Fig. 1) contains a melting chamber 1 and a heating chamber 2, made of quartz pipes, which through a spacer 3 are tightly interconnected. Spacer 3 is made of water-cooled 12Kh18N10T chrome-nickel steel and has an opening for connection to a vacuum system. The melting chamber is hermetically closed from above by the top cover 4, on which the sluice loading chamber of the metal charge 5 is located. Inside the melting chamber there is a melting and casting unit, consisting of a ceramic crucible 6, covered by an inductor 7, which are mounted on a common base, equipped with a rotation mechanism (not shown ), resting on the stand 8. The stand 8 is connected to the spacer 3. A vacuum shutter 9 located below hermetically connects the heating chamber to the mold loading chamber 10. Movable plate 11 mech The displacement mechanism can be moved in the vertical direction with a spindle 12 and a vertical displacement mechanism (not shown). A rod 13 is mounted on the plate 11, having a central hole 14 for supplying a cooling inert gas, argon. On the stem there is a base 15 (ceramic, molybdenum) having protrusions (teeth) 16 evenly spaced around the circumference, which can enter the grooves (slots) 17 of the stand 18 (ceramic, molybdenum) (Fig. 2). The mold 19 rests on the base 15 through a pallet 20. The device comprises a flexible gas hose (not shown) connecting the central hole 14 in the rod through a movable plate 11 and a sealed inlet at the bottom of the loading chamber with a cylinder with compressed argon (not shown). The quartz heating chamber 2 is externally covered by coils of the inductor 21, which heats the electrically conductive graphite holder 22 by high-frequency currents, radiation heating the mold 19. The high-temperature zone of the heating chamber is insulated from above and below, as well as from the quartz pipe 23. The supply of molten metal 24 from the crucible 6 to form 19 is carried out through the filling funnel 25 located on the support 26 (ceramics, molybdenum). The support 26 is connected to the spacer 3. The mold loading chamber is sealed by a lid 27. A water-cooled adapter 28 made of chromium-nickel steel is located between the lower end of the heating chamber and the vacuum shutter. The finished casting 29 (Fig. 3) is removed from the loading chamber through a vacuum shutter 9 and a cover 27.

To ensure tightness, individual elements of the device body are connected through elastic gaskets.

The ends of the melting and heating chambers are cooled by metal annular water-cooled shirts.

The proposed device works as follows.

On the stem 13, a base 15, a pallet 20 and a mold 19 are placed. A cover 27 tightly closes the mold loading chamber 10. When the vacuum shutter 9 is open, the mold is inserted into the heating chamber 2 by the vertical movement mechanism 2. The protrusions 16 of the base 15 slide along the grooves 17 of the stand 18 . After raising the base 15 slightly above the stand 18, the stem with the base rotates clockwise about 45 ° relative to the vertical axis and, when the rod is moved back down, the base 15 sits on its stand with its protrusions 18. The stem continues to move down and out of the heating chamber. The vacuum shutter 9 closes and seals the heating chamber. The melting chamber 1 is hermetically closed by the top cover 4. By a vacuum system, the residual pressure in the chamber is brought to a level of no more than 10 ^-1 Pa. The inductor 21 is turned on and the graphite holder 22 by radiation heats the mold 19 to a predetermined temperature. At the same time, through the lock chamber 5, a metal charge is loaded into the melting crucible 6, melted and the metal 24 is poured into the mold 19 through the filling funnel 25. Then the pressure in the heating and loading chambers is equalized, the vacuum shutter 9 opens, the rod 13 rises, slightly raises, slightly raises the base 15, together with the mold, rotates back counterclockwise by 45 ° relative to the vertical axis and the mold 19 begins to be displayed downward from the heating chamber to the loading chamber. In this case, the protrusions 16 of the base 15 slide along the grooves 17 of the stand 18. At the same time, a stream of compressed argon is supplied to the lower zone of the mold through the central hole 14 of the rod. In this case, the crystallization of the liquid metal begins from the bottom zone of the mold and, due to the created temperature gradient, continues in the upper direction with the shrinkage pores being removed to the upper part to obtain a uniaxial casting structure, after which the heating furnace inductor is turned off. The vacuum lock hermetically closes the heating chamber. After cooling the casting, air is poured into the loading chamber and the mold is removed with casting by opening the lid 27.

The temperature control of the molten metal in the melting crucible and the heating furnace is carried out by stationary platinum-platinum-rhodium thermoelectric converters and radiation pyrometers.

Example.

The proposed device was cast 29 hollow ball plugs with a diameter of 95 mm from stainless steel 12X18H10T weighing 1.2 kg (Fig. 3). The mold 19 was mounted on the rod, introduced into the heating furnace 2, turned clockwise by 45 ° C and lowered to the stand 18. The rod 14 was brought down into the loading chamber 10 and the vacuum shutter 9 was closed. After turning on the inductor 21, the temperature in the mold was increased to 1530 ... 1550 ° C, then the mixture was melted in the crucible of the melting furnace 6 and, at a temperature of 1570 ... 1580 ° C, it was poured into the mold 19 through the filling funnel 25.

Then the vacuum shutter 9 was opened, the rod was introduced into the heating furnace, raising the base 15 (relative to the stand 18), turned its relative vertical axis counterclockwise by 45 °, and the mold 19 was brought out of the heating furnace into the chamber at a speed of 5..8 mm / min loading, at the same time a stream of compressed argon was applied to the lower zone of the mold through a central hole in the stock. The vacuum shutter was closed and the heating chamber was sealed. After cooling the casting to 500 ... 700 ° C, the air was charged into the chamber and the mold was removed with casting 29 by opening the lid 27. The casting was removed from the mold by breaking it.

The cast was cut in half. Studies have not revealed the presence of pores and other defects in the halves of the casting 30 (Fig. 4).

Claims (3)

1. A device for producing directional crystallization castings, comprising a melting chamber, in which a rotary melting and casting block consisting of a crucible and an inductor is placed on the axis, a mold casting chamber, in which a heating block is located, consisting of an inductor placed outside the chamber, a heat insulator and an electrically conductive heater arranged concentrically, a mold loading chamber, and a mold installed on a rod equipped with a mechanism for vertical movement of the mold, vacuum a shutter located between the heating chamber and the mold loading chamber, a casting funnel placed on a support mounted on a spacer, characterized in that the melting chamber and the heating chamber are made of cylindrical quartz tubes, between the ends of which there is a water-cooled metal spacer having an opening for connections to the vacuum system, the melting and casting unit is placed on the rack, while the rack and the support of the casting funnel are placed on the spacer, and a central hole is made in the rod for I supply inert gas to the base of the mold. 2. The device according to p. 1, characterized in that the spacer is made of chromium-nickel steel. 3. The device according to claim 1, characterized in that an annular water-cooled metal adapter is installed between the heating chamber and the vacuum shutter.

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