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Optimized cam profile calculation for a rotating knife application

IP.com Disclosure Number: IPCOM000022347D
Original Publication Date: 2004-Apr-25
Included in the Prior Art Database: 2004-Apr-25

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Abstract

A common application for a rotating knife is cutting a material which is rolling off a wheel into equal-sized pieces. The knife cuts the material "on the fly", i.e. while the material is rolling off the wheel and comes pass the cutting place the knife cuts the material into equal-sized pieces. Fig. 1 shows a typical installation. The cutter has to be moved with the same velocity as the band (horizontal movement) overlaid with the cutting movement (vertical movement). The horizontal velocity of the cutter has to be the same as the band velocity. The velocity of the band is measured with the measuring wheel. This value is used to calculate the angular velocity and the angular acceleration of the rotating knife (the cutter). To do this calculation a cam profile is used to transform the values acquired with the measuring wheel into the angle, angular velocity and angular acceleration of the rotating knife. To calculate the ideal (theoretical) cam profile it is obligatory to use the trigonometric arc sine function. In a real setup this function is implemented as a polynomial approximation. Up to now this cam profile calculation is done in first order polynomial approximation (linear approximation) which leads to large deviations of the real horizontal position of the cutter to the position of the band.