CS196545B1 - Method of electroslag production of the moulded castings and facility for making the same - Google Patents

Abstract

Electroslag remelting of castings to produce finished castings using a consumable electrode which is joined by melting onto a component which is also immersed in the molten slag. The component is immersed in the molten slag to between 0.2-0.6 the depth of the slag at the start of the process. The cross-section of teh consumable electrode should pref. be at least equal to the cross-section of the component at the start of the process, and the pref. plant has means for inserting the component up through the mould base into the molten slag, the mould base being made of at least three segments which are pressed inwards radially onto the component, to clamp the latter and cool it by thermal conduction. Used for mfr. of components for power plant, atomic power stations, rolls for cold-rolling mills and crankshafts etc. The high quality and homogeneous structure of the product increases their working life.

Description

ŠTŽPANOVIC ing., SAPUNOV VIKTOR JEVGENIJEVIC, KARPOV VLADIMIR ALEXEJEVIC ing., KOV-NJA VLADIMIR JAKOVLEVIC ing., MOSCOW (USSR)

Method for electrostrinking of production of shaped castings and apparatus for its implementation

The present invention relates to electrometallurgy and, more particularly, to a method of electroslag production of molded castings and to apparatus for carrying out the same.

The use of the invention is most effective in the manufacture of particularly high quality components and components, such as semi-finished products for the lids of fittings for atomic power equipment, cold rolling cylinders, crankshafts, T fittings and connecting rods used instead of forged or forged and welded constructions for the same purposes · The first industrial series of cold rolling rolls, coated with electro-slag remelted metal and tested under operating conditions, confirmed that their service life doubled to tripled ·

The high quality and uniformity of the electroslag melted ingot metal has led to the idea of casting cast rolls made by electroslag remelting in shaped crystallites.

It is known to produce semi-finished products, e.g. rollers, by electroslag remelting, wherein one or more metal electrodes are melted in the slag bath. The electrodes melt in at least two cooled crystallisers having different cross-sectional Hy and ‘are superimposed on separate lift trucks. The trolleys and the electrodes above it are moved vertically.

19β 545 direction along columns ·

The disadvantages of these methods and apparatuses are that in the manufacture of blanks having different cross-sections in height, a different electrode is required for each cross-section of the blanks to be produced, and the electrode replacement causes melting breaks that deteriorate the metal quality of the blanks. In addition, slag must be added or removed during remelting, which causes difficulties in operating the equipment.

More preferred are methods for casting the billet rolls by electroslag remelting in a crystallizer having a diameter equal to the diameter of the roll body. A fused part is placed in the crystallizer on the side of its base ©, which corresponds in shape and dimensions to the roll pin and fuses to the base of the casting at the beginning of casting. The Poetraveo crystallizer has an aperture whose diameter corresponds to the diameter of the fused portion that forms the cylinder pin. The base of the crystallizer is vertically divided into two parts under which the prisms are arranged.

Neither this method and the device do not assure the quality at the point of erection of the fused cast part. In addition, the vertical division of the base into two parts results in the base deforming due to the expansion of the fused part during heating, and after the first remelting the hole diameter does not correspond to the original diameter of the fused part. The resulting gap must be sealed to prevent liquid slag and molten metal from escaping. Thus, from melting to melting, the difference between the diameter of the fused part and the diameter of the hole in the base increases, which eventually causes the crystalliser base to fall off rapidly from the machine. Operation of such devices is difficult.

It is an object of the invention to overcome these drawbacks. Another object of the invention is to ensure a guaranteed quality of fusing of the fused part to the casting body, to improve the operating conditions of the device and to extend the life of the base crystallizer.

The main object of the present invention is to provide a process for the electroslag production of molded castings with the simultaneous fusing of the individual parts either rolled or cast or forged, ensuring high quality of both the casts themselves and at the melting points.

The object is solved by a method of electroslag production of molded castings and by melting a consumable electrode in a slag bath under the influence of electric current and by fusing a pre-fabricated part according to the invention. 6 depth slag bath.

The apparatus for carrying out the method has at least a part of the crystallizer base made of several parts, connected along the vertical surfaces and in the formed passage a fused part which protrudes from the crystallizer base and is connected to the electric current source via the electrically conductive jaws. in that the parts are pressed by the elastic elements to the fused part and the electrically conductive member

198 545 r-leaves · are sliding.in horizontal plane and · are connected to the shifting device.

ý Method of electrospace. The production according to the invention ensures uniform melting of the front surface of the tinted part submerged in the atrus bath and guaranteed guaranteed melting both along the contour and in the cross-section to the casting body. According to the invention, it is advantageous to initially carry out the melting with the consumable electrode. . the cross section of which is at least equal to that of the fused part.

In this case, drops of remelted metal fall on. the fused part of the fitting part is already melted, thus ensuring its quality fusion.

Electrically conductive jaws. which are displaceable in a horizontal plane in the device according to the invention and are connected to a displacement device for pressing against the parts to be fused, providing a reliable electrical. contact and ·. they are · one.ducOhé and · operationally safe.

Execution. At least three of the parts, each of which according to the invention are connected to a resilient pressing element, eliminate the deformation of the pedestal caused by the thermal expansion of the fused part and increase the reliability of the device and the service life of the pedestal. ’'. '. , /. ·. · '’

Each part of the pedestal may be provided with a heat exchanger insert positioned at a point of contact with the fused part, the height of which is at least equal to the radius of the fused part. .

Such a provision of each part of the base with a heat exchanger replaceable insert allows them to be readjusted quickly. the transfer of casting production from one type and size to the other. .

The height of the inserts is at least equal to the radius of the part to be attached, which ensures that it is cooled down and at the same time prevents it. burn. walls · _ι ovlLné fused part at the beginning of melting and flow out of the slag and liquid metal. .

Dividing planes of pedestal parts. The interchangeable inserts are expediently designed as stepped.

Such a construction prevents liquid slag and metal from flowing out in the plane of the stopper at the start of melting when the fused part is thermally expanded and the parts, the base are not held together. v.

On the one hand, the use of the electro-fabric manufacturing process and the apparatus for carrying out the process according to the invention is limited. A noticeable reduction in production costs in the production of molded castings is effected by remelting and fusing the separate parts and, on the other hand, eliminating welding from the technological process. By the process and apparatus of the present invention, it is possible to enlarge castings using pre-cast or any preformed blanks such as castings. In addition, the solution according to the invention achieves a considerable economic effect in increasing the production properties of the metal and improving the quality of the castings.

In order to better understand the solution according to the invention, the examples of its walling are described with reference to the accompanying drawings, in which Fig. 1 shows the basic connection,

196 54S clarify. Fig. ² is a schematic representation of an apparatus for carrying out the method according to the invention; Fig. 3 is an axonometric view of a steel device for electrostructure production of shaped castings; and Fig. 4 is a section IV - IV of Figs.

2 ·

The principle of the method of electrostructure production of shaped castings is that the melting electrode 2 (FIG. 1) is introduced into the melting chamber of the crystalliser 2 and fused. part · 2 is set in the hole of the base ·. . coaxially with fusing electrode 1, then into the crystals ^and Toru £ Rental liquid type roztavetó ·· Etruscan ^'through. · Will arise. an electrolyte flow bath that is electrically permeable. and a source of electric current in the current circuit consisting of a melting electrode 1, a teat bath 4 and a fusion portion 2, and electro-electro-remelting commences. Fluxing. fused · · - parts. .2 · shall be initially. Carry out the welded part 2 to a depth of 0.2 to 0.6 · slag baths.

For clarity of illustration the use .technologický · · .úkon slag bath is regarded as the sum ^of & POR '''wherein R @ ^ ^{Rg and R} 3 and R tot ·

R totals R ^ + R-, + R>.

-odpor ol ^{p u} - Fusion ^{and the} ele tro · ^d 1

- fused part · 2 »

- from ^p or ^terminals - Fusion ^and elekteoda · 2 -. ^p o ^d Condition ^C · ^- · 6 ^-. · (· on both. · ^t s c ^h wounds ^and "melt · / electrode 2) ·. . -. .?; <ν ·· -'Λ _; - · '· /? <·>' ·? '· <? .

Total slag resistance. bath £ ·;

For simplicity, it is assumed that the melting electrode. . 2. and the fused portion 2 are symmetrically disposed in the melting chamber of the crystallizer. · 2. and thus it is possible to calculate resistances R2 and R1 equal to:.

At a constant electrical power input to the slag bath 4 from a power source 6 and the electrical power supply. The change in the inter-electrode gap even in the slag bath 4 is a redistribution of the electrical power, which is. ^; The resistances Rg and R. are close to each other and change noticeably as the immersion changes. The fused portion 2 in the slag bath 5 ' develops at the edges of the melting electrode faces. and a fused part 2 «with a reduction. interielectric. at an increased immersion depth 1 of the fused part 2 in the slag. · Spa. £, growing. the proportion of electric drive passing through the fused portion 2 which increases the melting speed of the end face fused with the portion 2. and at the same time. improves fusion quality ·

Furthermore, a faster melting of the front surface přitavovaná part 2 with · a deeper one immersion into the slag bath £ · explains the increased contact surface area přitavované Part 2 ⁸ a heated · struekovou bath £, ^No. Im ^s CE ^and now ^{y gloom} avovaná ^part 2 ^{p of} it in steusková ena l ^and Zn ^{even when} m is a melting body more high-grade casting ·

196 546

However, in the case of a small inter-electrode gap X, the electroslag process becomes arc-shaped, whereby the immersion depth 1 of the fused portion 2 into the slag bath 4 is limited to a maximum of 0.6 'slag bath depth.

At a depth of immersion of the fused portion 1 in the slag bath A of less than 0.2. depth ^t of ^the rus s ^{e la} harvest is ^{characterized} by ^{d ka} melting fusible ektro ^dy e ^r 1 z ⁱ with ^the An ^{and the} ovov ^{à la} zen jeet ^of not melted 'přitavované surface portion 2a is not ensured that the quality fusing.

If, at the beginning of the electroslag remelting, the melting electrode 1 has a cross-section equal to or greater than the cross-section of the fused portion 2, then the drip transfer of the metal of the consumable electrode 1 proceeds as follows. the remelted metal droplets impinge on the surface of the already melted přitavované 'portion 2 and ^yt VA ^R ejí ovovou common ^to L ^and women over the water, ^{b p &} STI řitavované No. 2 ·' thus achieved quality building přitavované portion 2 of the body casting.

Conversely, if a melting electrode X with a smaller cross-section than that of the fused portion 2 is used, then droplets. The electrode metal strikes the not yet melted front surface of the fused portion 2 &apos; fusing.

Further described is an apparatus for the electroslag production of shaped articles. castings with simultaneous fusing of separate pre-fabricated parts.

Apparatus for producing shaped castings electroslag obsahujetavnou electrode 1 (Figs. 2 and 3) introduced into the melter-cooled Cr stalisáttru ^y \ 2 a.přitavovanou part 2 »immersed in. the slag bath 5 from below. The melting electrode · X and the fused part 2 are connected to a power source 2.

The crystallizer 2 is seated on a pedestal 6 having an aperture aligned with the melting electrode. . . X to which · from. The fusible part 2 is inserted from below. 2 ·· assemble. The upper platform of the vertical displacement device 2, mounted beneath the base 6 on the base plate 8, and which lifts the fed portion 2 into the melting chamber of the crystallizer 2. Any known actuator can be used as the drive of the vertical displacement device X. eg electromechanical, hydraulic, pneumatic, manual, etc. <

In the horizontal plane, the current conductor to the fused part 2 is displaceable, electrically conductive jaws &quot;, their working surface immediately touching the surface &quot; part 2 · The electrically conductive jaws 2 are moved towards the fused part 2 - posoúyaoimor-. 10 (FIG. 2),. they are located between the two supports 11 and are mutually adjustable 'on the plane'. The displacement device 10 may be driven by any known drive, such as electromechanical, hydraulic, pneumatic or the like. -.

The forming part of the base 6 is made of three parts. Each part 12 is pressed against one another and to the fused part 2 by a resilient thrust member 13, which is positioned between the outer face of the part 12 and the support 14 displaceable in the radial direction.

Each part 12 of the base 6 may be provided with a 'heat dissipating insert '12 which noticeably shortens the assembly time of the device during the transition of the molding to another

19β 545 of the fused part 2 · The heat exchanger heat exchanger 15 is at least equal to the radius of the fused part 2 ·

When the height of the interchangeable heat transfer liners 15 which touches the fused portion is less than the radius of the fused portion 2, then ^{at the} beginning of production, the wall of the fused portion 2 is burned and liquid etruscan and metal leak. This is explained by insufficient heat dissipation from the fused portion 2, which thereby melts, and its walls burn through the exchangeable heat transfer liners 15.

The dividing surfaces 16 (Fig. 3) of the parts 12 of the base 6 and the exchangeable heat dissipating inserts 15 are stepped to prevent leakage of molten etruscus and metal at the start of production.

This construction is justified by the fact that the heated fused part 2 is thermally expanded, thereby opening the separated parts 12 and the heat exchangers dissipating the inserts 15 of the base 6 and creating slits into which liquid slag and metal can flow at the start of production. 12 and the replaceable inserts 15 of the base 8, which are formed in a stepwise manner, prevent the escape of the etrusk and the metal.

The device works as follows:

Heat exchangers 15 are attached to the separate parts 12 of the base 6, the dimensions of which correspond to the size of the fused-in part 2 to be attached thereto. The fused-in part 2 is lifted into the melting chamber of the crystallizer 2 to a height of 0.2 to 0.6 Depth of the slag bath 10 is pushed against the fused part 2 by the shifting device 10 and brought into the prone position of the electrically conductive jaws. 2, on the base 6, the slag bath 6 is formed and the electro-slag production begins by remelting the melting electrode 2 in the slag bath 6 under electric current. 6 of crystalliser 2 does not deform ·

Below are some examples of electroslag production of molded castings with simultaneous fusion of separate parts according to the above technology.

Examination of the influence of the immersion depth of the fused part 2 in the slag bath 6 and the ratio of the cross-section of the melting electrode 1 to the cross-section of the fused part 1 on the fusion quality was carried out both on the test laboratory equipment

Welded parts 2 were made by boosters · flux quality was evaluated on macro sanding and also by indestructible control procedures such as gamma radiation and ultrasonic inspection ·

An analysis of these results shows that quality fluxing is assured when, at the beginning of the electro-slag fluxing part, it is immersed in the slag bath up to 0.2 to

0 * 6 of its depth and when using a melting electrode 1 with a cross section not less than

198 545 cross section of fused part.

On ‘production equipment for. . The electro-slag production of shaped castings by the described process was produced by a test-industrial batch, about 200 pieces, lid blanks and fittings for atomic power equipment. All of them were subjected to a quality control of the matting region of the fused part and the parent metal of the casting by a non-disturbing inspection procedure.

It was found that the quality of the seal is good in all castings and defects were found on ^p ODO ^runs couples started. Neslitých bowls ^t ^ ^- and the like. "·.

From oru ^b extended from ^d to ^{h to} anýc Equals ^es is clear that the level of ^the mec ^h anic Yc ^H vlastaostí and VRU ^b s ^and toughness of the metal in the transition portion and · .odlitého metal by electroslag remelting are isotropic and correspond to similar characteristics of the rolled product by of samples discarded along the rolling fibers. ^;

Test melts on industrial equipment for electroslag production confirmed reliability, ease of operation, elimination of observable deformations - the base of the crystallizer and other components of the equipment.

Claims (2)

1. Method of electroslag production of shaped castings. by melting the melting electrode in the slag bath by an electric current and with a pre-welding of the part, characterized in that the immersion depth of the fused part is maintained at 0.2 to 0.6 in the slag bath. range 2. Apparatus for carrying out the method according to claim 1, wherein at least a portion of the pedestal is made of a plurality of parts joined along vertical surfaces and in a vertical position. forming openings is disposed přitavované portion which protrudes from the base of the crystalliser and is connected to a source of electrical current through the electrically conductive · jaws, characterized in that the parts (12) ^Base-1 (6), · -. and the electrically conductive jaws (9) are displaceably in the horizontal plane and are connected to the suction port. · Mechanism '- (10). / crystalliser 4 drawings 19B 545 Giant. 2 j 19β 545