Device for the yield-point-controlled tightening of screws

摘要

The device for the yield-point-controlled tightening of screws has a spindle (1) for a tightening tool (2), which spindle (1) is driven by an electric motor spindle drive (4). The torque and angular position of the spindle (1) are detected by a torque sensor (5) and an angle sensor (6) respectively. The detected torque values are digitized by a digitizer device (7). A first subtraction device (9) forms the moment differences between respectively successive torque values. The torque values are averaged in an averaging device (10). A second subtraction device (11) forms the average-value differences in each case between two successive average values of moment differences. A detector device (12) detects negative average-value differences, the number of which is stored in a counter (13). A comparator device (14) compares the number of negative average-value differences detected with a predetermined limiting number and, when this number is reached, a cut-off device (15) cuts off the spindle drive (4). In addition, an adding device (16) can be provided for continuously adding the average-value differences (with the correct mathematical sign) and a second comparator device (17) can be provided for comparing the added-up value with a limiting value which can be predetermined, the cut-off device (15) not [lacuna] the spindle drive (4) until this limiting value is additionally reached ... Original abstract incomplete. <IMAGE>