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EQUIPMENT FOR ELECTROSLAG CASTING

The standard equipment used for the ESC process (the unit for feeding consumable electrodes into the mould cavity and controlling their melting process in the sand mould, the mould and electric power source) and the auxiliary equipment (a unit for melting and pouring the slag and a stand for assembling and welding of electrodes) are practically the same as for the ESR method.

Until recently, for producing cast products of any shape the water-cooled casting moulds were created in such a way that to provide the successive casting formation by gradual filling these moulds with metal during the electrode remelting. Such an approach to the ESC problem allowed to use the commercial ESR units. In the ESC process, however, the casting mould, unlike the ESR, is the most important part of the unit. It is of a much more complicated shape than the ESR unit mould, the shape being determined by configuration of the billet melted.

Obviously, the most complex-shaped castings are obtainable by making use of the moulds which are stationary with respect to the castings. Such moulds may be subdivided into two types, the first comprising the moulds in which the casting is made as a whole, while in the second the linking part of the future article is cast first and the parts to be linked, already made by the ESC or another method and inserted into relevant holes of the mould, are fused up to the said linking part.

In the ESR the removal of round-, square- or rectangular-section ingots is no problem at all, the mould side wall having usually no joints in this case. When melting shaped castings having lugs and recesses, the mould should necessarily have joints allowing to break it into more simple elements. These joints make it possible to liberate the casting from individual parts of the mould.

With the casting configuration getting more intricate, the number of joints grows too. In their turn, the detachable moulds may also be subdivided into two types. Those which are dismantled after a complete cooling down of the casting belong to the first type. Should, however, some parts of the mould happen to get pinched between the casting projections getting shrinked when cooled down, provision is made for the casting portion already solidified to be stripped from the relevant mould parts. Thus, a necessity arises to strip the casting consequently part by part in the process of its making. Such casting moulds belong to the second type.

Until now we discussed the moulds in which both the fusion of electrodes and solidification of the molten metal casting run in parallel. The ESC mould with the metal pouring comprises at least two parts, stationary part where the casting is formed, and a movable one, or a melting unit, where the molten metal is accumulated. The mould cavity is confined by three water-cooled walls. Along the fourth side, which is open, the melting unit is movably secured, the latter presenting a water-cooled metal box structure with the space for fusing consumable electrodes confined from three sides by relatively low-height walls. The fourth low-height wall of the melting unit has a threshold for metal discharge and is intended to shape the surface of casting made in the stationary mould. The mould itself serves as a fourth wall. Depending on the complexity of the casting, the mould may have joints to facilitate "stripping" of the ready-made casting and is also provided with several cavities which are metal-filled in from a single movable unit.

Both in the ESC and ESR technologies, the casting mould is a water-cooled crystallizer. For the ESR typical is an intensive cooling down of the whole mould, this having little effect upon the quality of the outer surface of a round or square-shaped ingot. For the ESC a uniform dissipation of heat from all portions of the casting mould with the heat supply to the parts remote from electrode fusion area being non-uniform, leads to deterioration of the casting surface quality.

Task 1.

Pronounce correctly the following words and word combinations from the text “Equipment for ESC”:

the detachable moulds, rectangular-section ingots, a uniform dissipation, the electrode remelting, the gradual filling, the initial stage, to dismantle, necessity, consequently, stationary parts, relatively, a threshold, the surface of casting, to facilitate.

Task 2. Translate the following words and word combinations into English:

подача витратних електродів у ливарну форму, контролювати плавильний процес, джерело електроенергії, допоміжне обладнання, стенд для установки та зварювання електродів, вироби будь-якої форми, створювати ливарні форми, поступове заповнення, переплав електродів, виливок, користуватись, нерухомий, частина, яка об’єднує, виріб, вставити у відповідні отвори, з’єднувати за допомогою плавлення, видалення злитку, прямокутний, кругле січення, виступи і заглибини, знімати (демонтувати), затискатися, фасонувати.

Task 3.

Give the Ukrainian equivalents to the following words and word combinations:

the initial stage, to provide, the cast products, the standard equipment, an approach to a problem, to employ, complicated shape, the most complex-shaped castings, to obtain, to make use, square section, joints, to break the mould into elements, to dismantle, the complete cooling, to get pinched, the casting projections, the solidification of the molten metal, the metal pouring, to accumulate the molten metal, to confine, an uniform dissipation.

Task 4.

Translate the following sentences into English using given words and word combinations in italics:

lugs and recesses, joint, to liberate, the detachable moulds,a complete cooling, to dismantle, to get pinched, the casting projections,the cooling process, to confine, water-cooled walls.

1. Якщо у формі виливок має виступи і заглибини, ливарна форма повинна мати спеціальний пристрій для рознімання. За допомогою такого пристрою для рознімання інженер вивільняє окремі частини виливка з ливарної форми.

2. Знімні ливарні форми поділяють на два види. Знімні ливарні форми, які видаляють після повного охолодження, відносять до першого типу.

3. Окремі частини ливарної форми можуть затискатися між випуклими частинами виливка при усадці в процесі охолодження.

4. Порожнина ливарної форми обмежована трьома стінами з водним охолодженням.

Task 5.

Answer the following questions:

1. Can you name the components of the standard equipment and the auxiliary equipment used for the ESC process?

2. What is the most important part of the unit in the ESC process unlike the ESR process?

3. Being the important part of the ESC process, the casting mould used in the ESC process is much simpler in its configuration, isn’t it?

4. To obtain the most complex-shaped castings, an engineer makes use of the moulds which are stationary with respect to the castings. Such moulds are subdivided into two types. Can you name them?

5. How many types of the detachable moulds do you know from the text? Describe them.

6. How many parts does the electroslag casting mould comprise?

7. Give a detailed picture of the melting unit of the ESC process. Where is a threshold for metal discharge situated? What is a purpose of this threshold?