GB1258641A - - Google Patents

Abstract

1,258,641. Stretching; rolling. BWG BERGWERK UND WALZWERK - MASCHINENBAU G.m.b.H. 27 Jan., 1969 [15 Feb., 1968; 22 Nov., 1968], No. 4509/69. Headings B3E and B3M. A stretching device for continuously stretching strip comprises first and second roll stands 1, 2, each stand having a plurality of rolls 4a-4d, 5a-5d, each roll of the first stand driving a fluid pump 6a-6d and each roll of the second stand being driven by a fluid motor 7a-7d, the torques of the pumps and motors being graded, preferably in the ratios 2: 4: 8: 16 and 16:8: 4: 2 respectively, to produce a desired distribution of tensile forces in the strip. The pumps and motors have their high-pressure sides connected to a common high-pressure fluid line 8 which is fedby a pump 9 and has a pressure control means 15 associated therewith. A second pump 14 is connected to the low-pressure side of the pumps 6a-6d and has a pressure control means 16 associated therewith, this pump causing the pressure difference across the pumps 6a-6d to be lowered so that the motors 7a-7d can turn their respective rolls to draw the strip through the stands. Alternatively, the strip may be drawn through by an independent means (not shown) on the downstream side, 3b, of stand 2. A skin-pass roll stand (29) driven by the strip, Fig. 3 (not shown), may be placed between stands 1 and 2. The pressure in the high pressure line 8 is preferably controlled by sensing devices (21), (22), Fig. 3, which measure the amount of stretch imparted to the strip. A strip tensiometer (17) measures the tension in the incoming strip, directly compares it with a standard and alters the pressure in line 13 so that the motors draw the strip through faster or slower until the required tension in the incoming strip is achieved.