UNIVERSAL JOINT ARRANGEMENT FORMING A ROTARY DRIVE TRANSMISSION MECHANISM

摘要

A variable-velocity drive is provided which serves to so control the peripheral velocity of a window cutter roller in an envelope machine working from the reel that, irrespective of the developed length of such roller, the velocity of the window cutter is the same as that of the paper web for the time that such cutter is operative on such web. To this end, the variable-velocity drive is basically devised from a number of universal joints interconnecting shafts whose axes intersect one another at an angle of up to approximately 45 DEG ; the universal joints are so offset from one another in rotation that the variations or irregularities arising in the discrete joints are superimposed upon one another so as to have an amplifying effect. Since any one such universal joint arrangement passes through two velocity maxima and two velocity minima per revolution, gearing is provided on the input and output side to make the universal joint arrangement run at half the cycle speed.