ELECTRICAL CONTACT UNIT FOR HEAT TREATMENT AND STRETCH STRAIGHTENING OF PIPES, RODS AND SHAPED SECTIONS

FIELD: metallurgy. ^ SUBSTANCE: unit for electric contact heating contains a transformer, a frame with longitudinal guides, current-carrying contacts mounted on the frame, movable contacts mounted on the support of longitudinal movement, a hydraulic cylinder for movement of the movable contacts and a controlled hydraulic drive. Between the support of the moving contacts and a hydraulic cylinder a pneumatic plunger-type piston is mounted coaxially with the hydraulic cylinder on the platform. The pneumatic cylinder plunger is rigidly connected to the piston rod of the hydraulic cylinder and has a length LH of stroke not less than the value of thermal elongation of the heated workpieces, while the length LH of stroke is limited by controlled stops, fixed on a platform of the hydraulic cylinder, and is determined by the expression: where is a relative force of the axial tension of the workpieces before heating at a temperature of t0; is a relative force of the axial tension of the workpieces at the end of heating to a specified temperature tK; F is cross-sectional area of the pneumatic cylinder working cavity, P0 is force of the axial tension of the workpieces before heating, Pk is force of the axial tension of the workpieces the end of heating; öl=l0(tK-t0) is lengthening of the workpieces when heated to tK; is a coefficient of linear thermal expansion of metal of the workpieces; l0 is the length of the workpieces heated part; =pk/pa; pa is the atmospheric pressure, pk is pressure of air or gas in the pneumatic cylinder working cavity with its length LH. ^ EFFECT: expansion of process functionality of electric contact heating units for combining operations of heat treatment and stretch straightening that guarantees increased operational characteristics of the product. ^ 3 cl, 4 dwg Изобретение относится к металлургии и может быть использовано для финишной термической обработки, совмещенной с правкой растяжением, труб прутков и профилей, в частности, из коррозионно-стойких сталей. Установка для электроконтактного нагрева содержит трансформатор, станину с продольными направляющими, закрепленные на станине неподвижные токоподводящие контакты, подвижные контакты, установленные на суппорте продольного перемещения, гидроцилиндр перемещения подвижных контактов и управляемый гидропривод. Между суппортом подвижных контактов и гидроцилиндром соосно с последним закреплен на платформе пневмоцилиндр плунжерного типа, плунжер которого жестко соединен со штоком гидроцилиндр