Model 14: Stepdwell motion of a belt, used in a paper cutting machine

Kinematic scheme:

Dimensions:

 Dimensions [m] a 0.060 b 0.024 c 0.140 d 0.120 e 0.056 f 0.264 g 0.076 h 0.170 k 0.252 m 0.150 n 0.174 u1 0.049 u2 0.280 r1 0.0334 r2 0.0143 a0 -0.9 rad b0 2.85 rad

Explanation:

The belt part at the green slider (between the rolls at distance m) performs a step-dwell motion. The green slider is driven by the inverted crank-slider mechanism (oscillatory motion). When moving to the right, the slider velocity compensates the constant belt speed. While the belt has no velocity, some device (the yellow block attached at the crank-slider mechanism) can operate on the belt. The diagram below shows the step-dwell motion. This machine can for instance be used for cutting paper sheets supplied from a drum of paper.

Literature

Remarks: To perform the step-dwell motion, theoretically  the following condition must hold: r1=2a(h-d)/(a+d)=0.0333 m.

In the model a toothed belt wheel with 42 teeth at pitch 5mm is used, which yields r1=0.0334 m. The model has the option to adjust the position of the pin-joint on the green slider, perpendicular to the sliding direction, to adapt the h-value of the condition.