Patent GB-1222977-A (GB)
Title: Material-cutting apparatus
IPC: B23D36/00
Filed: 1968-01-29
Abstract: 1,222,977. Shearing. WESTINGHOUSE ELECTRIC CORP. 29 Jan., 1968 [16 Feb., 1967], No. 4485/68. Heading B3W. A shearing line for cutting up lengths, e.g. steel bars into billets 14 includes an entry table 18 to which bars 12 are fed by conventional means 19, a hold down clamp 28 and a shear 26, the cutting operation being controlled by means for sensing the tail end of a bar at least when it is located at a predetermined reference point Po along the table, means for advancing the bar along the table for cutting, means for checking the advancing means so that the cuts take place at positions along the bar corresponding to at least one predetermined front end cropping and at least one billet free of tail end waste according to a cutting schedule for the particular bar. A push bar 34 is clamped to a bar 12 fed to the table 18 and moved along tracks 38, 40 in the form of closed loops by, e.g. chains (not shown), the push bar passing under the table after each bar has been cut up. Two pushbars may be used, one approaching the entry end of the table 18 as the other leaves the delivery end. The chains are driven by one or more motors 44 and a switch 46 on the push bar is actuated by means (not shown) on the guides to signal to the cutting control means that the speed of the pushbar should be limited prior to its clamping to a bar 12. A switch 48 is actuated by the pushbar at reference position Po and a switch 50 actuated by the push bar after its disengagement from the tail end of a bar initiates the feed of a new bar to the table 18. With a cutting control arrangement (Fig. 2, not shown) for use when bars of a minimum length L are being cut up, the pushbar first positions the bar 12 with its tail end at point Pc and the clamp 28 and shear 26 are operated to front crop the bar if necessary to the length L. A cutting schedule for each bar entered through a tape or card reader into a control (70) is fed to a push bar digital position regulator (68) which controls the speed of the motor(s) 44 through a signal applied to a conventional speed regulator (62). A position error detector controls the level of the signal; at zero error the signal value is zero and the motor is stopped. Error detection is made by comparing a command number in the register of the regulator (68) with the amount of movement of the tail end of a bar from the position Po, at which the switch 48 is actuated to set a counter in the regulator to a value higher than would correspond to the longest possible bar; the amount of movement is measured by a pulse generator (84) or the like coupled to the motor(s) 44, which feeds back to the regulator (68). When the downcount corresponds to the tail end being at position Pc the bar is front cropped. Any additional front cropping command is then entered in the register of the regulator and the bar moved till there is a zero error condition and a further cropping is carried out. The scheduled billet lengths are successively fed to the regulator and successive zero error downcounts position the bar for shearing. With the arrangement of Fig. 3, the actual length of each bar is detected by means of the switch 48 and a head end detector 52 (e.g. photocell or sonic detector) and optimum billet lengths are calculated in a computer. Prior to cutting operations a batch of orders for billets is fed to the computer which is programmed to take into account in the calculations such factors as the billet lengths and quantities making up the batch of orders and the projected frequency of the occurrence of bars of the same length as the bar being cut. With each cutting control arrangement waste at the tail end is obviated as the last piece is designed to be an exact billet length.