Determination of material's tightening force with chipper knife
Baranov N.F., DSc in technics, рrofessor,
Fufachev V.S., PhD in technics, associate professor,
Stupin I.V., applicant
Vyatka State Agricultural Academy, Kirov, Russia
Chippers designed for chopping wood at the sawmill waste, produce of wood chips could be used in agriculture; they used at development of lands derived from the rotation overgrown with undergrowth and bushes. The improvement and optimization of parameters of chipper RB-750 with a combined working body, the effectiveness of which depends on a number of structural factors: the angle tightening angle pinch location shearbar and others is conducted in Vyatka State Agricultural Academy. Angle of incidence in the cutting process changes its value and affects the strength of the material tightening with knife. The maximum value of a tightening force is possible at the smallest impact angle, but it degrades the quality of the finished product. To justify the design parameters of the working body theoretical research were conducted with the consideration of two major cases: when the angle of incidence is less and more than 90˚. The obtained dependences allow to determine the parameters of the cutting pair providing material delay at changing cutting conditions: the ratio of the components of the cutting force; the coefficient of friction of material on the surface of working bodies. Experimental studies on confirming of the theoretical assumptions were made in a laboratory machine which allows to register the effect of a tightening of sample material with knives of grinding drum of the working body. Completed experiments yielded a regression model that characterizes the effect of investigated factors on the strength of a material tightening with knives. The experimental results confirm the theoretical assumptions put forward and allow to draw conclusions about the optimal values of the factors: angle of delaying γ = 4.5...4.8˚; location of shearbar below the horizontal axis of the drum on 20...21 mm; angle of crushing material χ = 30˚.
Keywords: chipper, experimental machine, cutting process, cutting force, tightening strength, impact angle, pinching angle, optimal values
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