Bending machine with digital electronic control of bend angle

Claim 1

In a bending machine having a bending shoe means including a rotatable bending shoe, an electric motor actuated for driving the bending shoe in rotation and means for drivingly connecting the bending shoe and electric motor, the combination of: (a) sensing means for determining the degree of rotation of the bending shoe by sensing the degree of rotation of the bending shoe means in increments and generating an increment signal for each increment of rotation, (b) counting means for receiving and counting the increment signals from the sensing means relative to a start reference count, (c) referencing means for providing the start reference count in the counting means before shoe rotation, (d) storage means for storing a finish count in the counting means corresponding to the number of increment signal counts relative to the start reference count counted for rotation of the bending shoe to a desired bend angle, (e) means for transferring said finish count from the counting means to the storage means, (f) comparator means for comparing said stored finish count to the actual count for the bending shoe during bending, (g) control means for controlling the motor and responsive to a signal from the comparator means indicative that the actual count equals or exceeds the stored finish count for terminating motor actuation to stop motor driven bending, and (h) rollover means operative in response to a count in the counting means counted during rotation of the bending shoe in a direction to unload a workpart for permitting rotation of the bending shoe in the unload direction past the start reference count.