RU2545979C1 - Device to produce castings by directed crystallisation - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy and may be used for producing castings from steels and alloys. This device comprises heating chamber 1, cooling chamber 2 and rod drive chamber 3 that make an integral sealed vacuum chamber. Rod drive chamber 3 houses the actuator of vertical displacement of die 23 and of turn of pan 43 about vertical axis of rod 38. Pan turn actuator 43 comprises vertical pipe 42 with square hole fitted in the hole of rod 38 with clearance, square shaft 45 fitted in said pipe with clearance and drive square shaft turn about vertical axis located at rod drive vacuum chamber bottom 3. Cooling chamber 2 accommodates die cooler 23 with movable reflecting screens 32 and 34, Retainer of die in heating chamber 1 is composed by slotted disc 24 arranged at cooled pan and aligned therewith and circular slotted support 21 secured at the bottom of heating chamber 1 and provided with slots to interact with ledges of slotted disc 24 at rod with die lifting into heating chamber.

EFFECT: enhanced performances.

2 cl, 6 dwg

Description

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

A device is known for producing castings with directional crystallization, containing a vacuum heating chamber, a lock chamber for loading a mold, horizontal and vertical movement mechanisms with suspensions on which the molds are fixed. In the heating chamber there is a melting furnace, a furnace for heating casting molds, a container with a liquid metal cooler and a lifting mechanism [RF patent No. 2267380, IPC B22D 27/04, publ. 01/10/2006].

The main disadvantage of the device is the need to place the mold on the suspension for immersion in a liquid metal cooler. Unstable and brittle ceramic molds often come off and fall into the liquid metal cooler with the corresponding loss of casting shape, failure of the liquid metal cooler, etc.

A device is known for producing directional crystallization castings, containing a vacuum chamber with end caps, an induction melting furnace, a mold heating furnace, a mold cooling unit is located below, a device for placing a mold with molybdenum rods and graphite jumpers, which prevents its deformation and destruction with its mechanism movements, a system of heat-insulating screens. The mold cooling unit is made in the form of a water-cooled annular vessel containing a coil of a water-cooled copper tube placed on a pallet made of graphite or ceramic. The device is also equipped with a lock chamber for loading a metal charge into a crucible of a melting furnace [RF patent No. 2492026, IPC B22D 27/04, publ. 04/10/2013].

After crystallization of the casting, the mold rises in the heating furnace and is removed from the chamber.

The disadvantages of the analogue

1. The need to use individual devices for placing the mold for various castings.

2. The device occupies a significant amount, by the size of which the dimensions of the mold and the useful working space of the heating furnace are reduced.

A device (prototype) is known for the manufacture of directional crystallization castings, containing a vacuum chamber, where a melting furnace with a crucible and an inductor, a resistance mold heating furnace are placed. Directly below the heating furnace is a cooling zone, which is a water-cooled ring. Under the heating chamber is a cooling chamber, a rod equipped with a vertical movement mechanism. The mold is supported by a water-cooled metal plate, which, after being lifted into the heating furnace, is fixed by means of clamps on a water-cooled frame, which is attached to the inner wall of the cooling chamber case. A set of plate carbon-graphite thermal insulators is attached to a metal water-cooled plate from below. During the entire heating process, an assembly consisting of a mold, a water-cooled plate and a set of plate carbon-graphite thermal insulators, mounted on a water-cooled frame, is located in the heating furnace. The heating and cooling chambers can be cut off from each other by an isolation valve. Immediately after heating and pouring the mold, the insulating valve opens, the stem rises, the assembly consisting of the mold, a water-cooled plate and plate carbon-graphite heat insulators sits on it, is freed from the water supply system and the water-cooled frame, and is output to the cooling chamber at a given speed, as a result of which directed crystallization of a molten metal with the orientation of the structure and the removal of pores in the upper part of the casting [Site of the company "CONSARC", www.consarc.com/brochures/vpic.pdf].

The disadvantages of the prototype

1. After lifting into the switched-on heating furnace, the lower part of the mold in contact with a metal water-cooled stove and located in the immediate vicinity of the cooling zone is constantly cooled, which increases the energy consumption of the process to maintain the temperature at the required level.

2. A complex system of a quick disconnect assembly for connecting to a water supply system and clamps to a water-cooled frame is needed.

3. A complex and dimensional movable vacuum seal is required between the rod and the housing of the loading chamber, which requires additional energy consumption to provide the required vacuum in the chamber.

4. A number of special casting methods require a long (1 ... 3 hours) curing of the mold in a heating furnace, for example, upon receipt of a reinforced casting with a working part from a wear-resistant cermet, when the working part is installed in the casting mold, fixed and sintered in it for a predetermined time . After that, the molten metal is poured into the mold, kept in the molten state for some time to ensure metallurgical bonds between the cermet working part and the metal base of the casting. However, in the prototype, long exposure times of the form, due to the presence in the lower part of the furnace of heating of the annular cooling zone and water-cooled plate, lead to additional significant energy costs.

An object of the invention is a device that provides the expansion of technological capabilities and reduce energy consumption when receiving castings.

To solve the technical problem, a device is proposed for producing directional crystallization castings, which contains a sealed heating chamber, in which a rotary induction melting furnace mounted on the side cover of the chamber, and a mold heating furnace located below the melting furnace, a cooling chamber with a mold cooling unit in the form of a water-cooled containers, an isolation valve located between the heating chamber and the cooling chamber, a mechanism for vertical movement of the mold, containing a rod passing through a vacuum movable seal in the lower wall of the cooling chamber, a tray with a cooled cavity mounted on the upper end of the rod, a form fixing mechanism in the heating furnace, a lock chamber for loading the charge into the crucible of the induction melting furnace, which is additionally equipped with a vacuum chamber for the rod drive located below the cooling chamber , a drive to rotate the pallet around the vertical axis of the rod, including a rotatable pipe with a square hole attached to the bottom of the pallet, located with a gap in the rod hole, quad a shaft mounted inside the pipe with a gap, and a mechanism for turning the square shaft around the vertical axis, located in the lower part of the vacuum chamber of the rod drive, by a block of movable reflective screens located in the upper zone of the mold cooling unit, while the form fixing mechanism is made in the form of a spline disk located on the cooled tray coaxially with it, and an annular spline support, mounted in the lower part of the heating furnace and having grooves with dimensions that ensure interaction with the protrusions of the spline disk when deme rod with the shape in the heating furnace forms the heating chamber, the cooling chamber and the drive shaft form a single chamber sealed vacuum chamber, and vertical movement mechanism is shaped in the upper part of the vacuum rod drive chamber.

The vertical movement of the rod is made in the form of a vacuum motor with a squirrel-cage rotor, a worm gear and a gear-rack transmission.

The essence of the proposed technical solution is illustrated by drawings:

FIG. 1 is a diagram of a device;

FIG. 2 - side cover of a heating chamber with a melting furnace - section AA in FIG. one;

FIG. 3 - a mold fixing unit in a heating furnace (the protrusions on the spline disk are supported by the protrusions of the spline support) - view “B” in FIG. one;

FIG. 4 - construction of an isolation valve — view “C” in FIG. one;

FIG. 5 - vertical rod movement mechanism - view “D” in FIG. one;

FIG. 6 - rotation mechanism of a square shaft - view "E" in FIG. one.

The furnace (Fig. 1) consists of three water-cooled vacuum chambers - a heating chamber 1, a cooling chamber 2 and a rod drive chamber 3.

In the upper part of the heating chamber is an induction melting furnace 4, consisting of a crucible 5 (Al ₂ O ₃ ) and an inductor 6 and intended for melting and pouring a metal charge 7.

The melting furnace is located on the basis of the rotary mechanism 9, mounted externally on the side sealed cover 8 of the heating chamber (Fig. 2). When the side cover is opened, the melting furnace is brought out, thereby providing free access to it for maintenance and repair work. A reflective screen 10 is mounted on the lid, protecting it from overheating. In the upper part of the heating chamber there is a vacuum shutter 11 and a lock chamber 12 for loading the metal charge 7 into the crucible.

Accurate measurement of the temperature of the molten metal is carried out by an immersion tungsten-rhenium thermocouple with a quartz cap 13, and the temperature of the form using stationary tungsten-rhenium thermocouples (not shown). Constant control of the metal temperature and shape is carried out by optical (radiation) pyrometers 14. The reflective screen 15 is designed to protect the vacuum shutter 11 from overheating.

The molten metal is poured into the mold through a casting funnel 16 (Al ₂ O ₃ ).

In the lower part of the heating chamber, there is a resistive heating furnace 17, consisting of a thermal insulator (graphite felt, Al ₂ O ₃ ) 18, heaters 19 (tungsten, graphite), a reflective screen 20, and a spline support 21 (Mo, Al ₂ O ₃ ) having in the hole, alternating grooves 22 between the protrusions (figure 3). Access to the heating furnace during repair work and its removal from the chamber during replacement is through the side cover 8.

The heating furnace is designed for heating and holding at a given temperature-time mode of the mold 23 (Al ₂ O ₃ ). It relies on a spline disk 24 (Mo, Al ₂ O ₃ ) and a spline bearing 21. The disk 24 has alternating grooves 25 between the protrusions along the perimeter. After rotation about a vertical axis by 45 °, the spline disk has the ability to move in the vertical direction relative to the spline bearing, while the protrusions of the disk pass through the grooves 22 of the support.

The spline bearing 21 is fixed to the water-cooled frame 26.

Between the heating chamber and the cooling chamber is located an isolation valve 27, designed to hermetically cut off these chambers from each other (Fig. 4). A water cooling unit 28, a removable metal container 29 with a reflective screen 30 are mounted on the isolation valve to protect the insulation valve from overheating and emergency situations (for example, liquid metal spills, etc.).

In the lower zone of the cooling chamber there is a mold cooling unit, consisting of a water-cooled casing 31 (Fig. 1). Above the cooling unit is a block of movable reflective screens consisting of a lower cylindrical reflective screen 32 with a vertical reciprocating drive 33 and an upper reflective screen 34 with a rotational drive 35 relative to the lower screen. The block of reflective screens is designed to reduce heat removal from the upper zone of the mold and casting during crystallization. The upper screen 34 may be made with or without a hole.

The cooling chamber has a side door 36 for loading and unloading the mold 23 using a cart with a telescopic manipulator and a fork 37.

In the chamber of the actuator rod 3 is a rod 38 with mechanisms of vertical movement and rotation.

The vertical movement mechanism (Fig. 5) consists of a vacuum motor 39, a worm gear 40 and a gear rack and pinion gear 41. Inside the rod 38 with a gap there is a pipe 42 with a square hole, to the end of which a pallet 43 with a cooled cavity 44 is rigidly attached (Fig. 3). Inside the pipe 42 with a gap, but with a rubber seal over the cross section (not shown conditionally), a square shaft 45 is placed, which is equipped with a rotation mechanism relative to the vertical axis (Fig. 6), consisting of a vacuum motor 46, a worm gear 47. The worm wheel is rigidly connected with a square shaft 45, which has the ability to rotate the pipe 42 and, accordingly, the pallet 43 and the spline disk 24. The square shaft has a Central hole 48 for supplying cooling inert gas (for example, argon) into the cavity 44 of the pallet 43, which has ERSTU gas outlet 49 (FIG. 3). The furnace operates as follows.

Insulation valve 27 is in the closed position. The heating furnace of form 17 is turned on, its temperature is brought to 1600 ... 1625 ° C.

Form 23 using a cart with a telescopic manipulator 37 is mounted on a spline disk 24 located on the rod 38 in the cooling chamber. After closing and sealing the side door 36, the vacuum system is turned on and the residual pressure in the chamber is reduced to a level of not more than 10 ^-2 Pa.

The isolation valve 27 is moved to the “open” position, the vertical movement mechanism motor 39 is turned on, and the mold 23 rises into the mold 17 heating furnace. The protrusions of the spline disk 24 extend along the grooves 22 of the spline support 21 and the spline disk rises 3 ... 5 mm above the support. After turning on the engine 46 of the rotation mechanism, the shaft 45, respectively, the spline disk 24 with the form 23 rotates 45 ° relative to the vertical axis, the rod 38 moves downward, while the spline disk, falling by 3 ... 5 mm, sits on its protrusions with its protrusions 21, and the rod continues to move down into the cooling chamber to its lowest position.

The isolation valve is in the closed position.

The mold in a heating furnace at 1600 ° C is maintained for 1.5 ... 2.0 hours.

15 ... 30 min before the end of the mold exposure in the heating furnace, the metal charge 7 is loaded into the crucible 5 of the melting furnace 4 and the inductor 6 is turned on. The metal is melted, its temperature is brought to 1550 ... 1650 ° C.

After holding the mold 23 for 2 hours, its temperature drops to 1500 ... 1550 ° C and the molten metal from the crucible 5 through the casting funnel 16 is poured into the mold. The mold with the filled metal is held for 5 ... 20 minutes, then the isolation valve 27 is opened. The rod 38 rises into the heating furnace, abuts the slotted disk with the mold, raises it by 3 ... 5 mm, turns back by 45 ° and starts to lower at a speed 3 ... 10 mm / min. The form, located on the spline disk, also lowers along with the rod, while the protrusions of the disk pass through the grooves 22 of the spline support. At the same time, through the central hole 48 of the square shaft 45, argon is introduced into the cavity 44 of the pallet 43 to the bottom of the mold with the required parameters.

After passing the spline disk relative to the spline support, the speed of movement can increase to 1500 mm / min, and the shape quickly sinks and sits on the base of the cooling unit 31. After that, the upper reflective screen 34 rotates and closes the lower cylindrical reflective screen 32 and the mold 23.

The isolation valve is in the closed position.

The molten metal crystallizes from the lower to the upper part of the mold with the removal of shrinkage shells in the upper part of the casting.

After cooling the mold to 250 ... 400 ° C and evacuating, the side door of the loading chamber opens, the stem with the mold rises up to the required value. The mold is removed from the furnace chamber by means of a cart with a telescopic manipulator, and the casting is removed by breaking it.

The next form is installed on the pallet and the next cycle for receiving the casting begins.

The technical solution allows:

- expand technological capabilities by equipping the device with a mechanism for fixing the mold in the heating furnace and a block of movable reflective screens located in the upper zone of the mold cooling unit;

- significantly reduce energy consumption during prolonged exposure of the mold in a heating furnace, for example, obtaining large-sized reinforced castings with a working part from wear-resistant cermets, to set and maintain a vacuum by eliminating a movable vacuum seal between the rod and the chamber body.

Claims (2)

1. A device for producing castings by directional crystallization, containing a sealed heating chamber, in which a rotary induction melting furnace is installed, mounted on the side cover of the chamber, and a mold heating furnace located below the melting furnace, a cooling chamber with a mold cooling unit in the form of a water-cooled container, insulating a valve located between the heating chamber and the cooling chamber, a mechanism for vertical movement of the form, containing a rod passing through a vacuum movable seal in the lower st nk cooling chamber, a pan with a cooled cavity mounted on the upper end of the rod, the mechanism for fixing the form in the heating furnace, a lock chamber for loading the charge into the crucible of an induction melting furnace, characterized in that it is equipped with a vacuum chamber of the rod drive located below the cooling chamber, the drive rotation of the pallet around the vertical axis of the rod, including a swivel pipe with a square hole attached to the bottom of the pallet, located with a gap in the rod hole, a square shaft located inside the pipe with a gap orom, and the mechanism of rotation of the square shaft around the vertical axis, located in the lower part of the vacuum chamber of the rod drive, by a block of movable reflective screens located in the upper zone of the mold cooling unit, while the form fixing mechanism is made in the form of a spline disk located coaxially with the cooling pan him, and an annular spline support, fixed in the lower part of the heating furnace and having grooves with dimensions that ensure interaction with the protrusions of the spline disk when lifting the rod with the mold into the mold heating furnace , The heating chamber, the cooling chamber and the drive shaft form a single chamber sealed vacuum chamber, and vertical movement mechanism is shaped in the upper part of the vacuum rod drive chamber. 2. The device according to p. 1, characterized in that the mechanism for vertical movement of the rod is made in the form of a vacuum motor with a squirrel-cage rotor, a worm gear and a gear-rack transmission.

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