Rotary cutter for successively cutting moving material to lengths

In a rotary cutter adapted for successively cutting a material to lengths in accordance with a rotary cutter rotational speed control pattern which is determined by the relation between a cutting length of said material and the circumferential length of said cutter, the combination comprising:

• coefficient generating means for computing an acceleration/deceleration coefficient indicative of variation of the rotational speed of said rotary cutter for every material travel speed detecting pulse in accordance with a preliminarily set material-cutting length, rotary cutter circumferential length and cutter cutting distance;
• function generating means for generating a rotary cutter speed control function in response to material travel speed detection pulses which are counted up or counted down in accordance with the acceleration/deceleration coefficient computed by said coefficient generating means and said rotary cutter rotational speed control pattern;
• speed computing means for multiplying together the speed control function generated by said function generator and a material travel speed obtained by converting said material travel speed detection pulses to obtain a product and then adding said material travel speed to said product to generate a rotary cutter operating speed command signal;
• error computing means for adding the sum of the speed control function generated by said function generator and said material travel speed detection pulse in response to the application of each said material travel speed detection pulse to compute the amount of rotation of said cutter and for subtracting an actually detected amount of rotation of said cutter form said computed amount of cutter rotation to generate a cutter follow-up error signal;
• acceleration computing means for multiplying together the acceleration/deceleration coefficient computed by said coefficient generating means and a square of said material travel speed to generate an acceleration signal to control the amount of current which generates a DC motor driving torque necessary to accelerate or decelerate said cutter;
• and cutter speed controlling means including a speed amplifier and a current amplifier, said cutter speed controlling means being responsive to said operation speed command signal, said follow-up error signal and said acceleration signal for controlling a cutter driving DC motor, wherein said follow-up error signal is fed to said speed amplifier and said acceleration signal is fed to said current amplifier.