Hybrid dynamically balanced saw frame drive

Abstract

In frame sawing machines, where a saw frame is driven by a crank mechanism, an inertial force produced by the saw frame cyclic motion significantly affects the machine foundation and also the saw frame driving system. This paper discusses the question how these serious using difficulties in machine performance can be eliminated. The authors present the principle of operation of the hybrid dynamically balanced saw frame driving system with the kinetic energy accumulator connected in parallel. The findings of numerical analysis are: this solution allows us to eliminate changing loads of the driving system and permits a reduction of the mass and dimensions of the machine, to eliminate a huge and expensive foundation, and to increase the working speed. Dynamisches Auswuchten von Kreissägeantrieben bei GattersägenSägegatter, die über Kurbelwellen angetrieben werden, sind Trägheitskräften unterworfen, die durch die Kreisbewegungen hervorgerufen werden. Die Trägheitsmo-mente übertragen sich sowohl auf die Sägefundamente als auch auf das Antriebssystem. In dieser Arbeit wird diskutiert, wie diese Schwierigkeiten ausgeschaltet werden können. Vorgestellt wird das Prinzip eines dynamisch ausgewuchteten Antriebsystems des Gatters mit einem parallelgeschalteten Energieakkumulator. Die Ergebnisse der numerischen Analyse besagen: Diese Lösung ermög-licht es, wechselnde Belastungen des Antriebssystems auszuschalten. Weiterhin besteht dadurch die Möglichkeit, die Masse und Abmessungen der Maschine zu verringern. Infolgedessen ergeben sich Einsparungen an starken und teuren Fundamenten, und die Arbeitsgeschwindigkeit kann erhöht werden. NomenclatureA accumulator (a flywheel or an additional mass) C constant value E energy E A accumulator energy E F saw frame energy E PU power unit energy E T total energy EM electric motor F saw frame F C force caused by a counterweight F IA inertial accumulator force F IF inertial saw frame force F T total exciting force i transmission ratio IA inertial accumulator J moment of inertia m mass m 1 counterweight mass m A accumulator mass m F saw frame mass M P E amplitude value of the motor output torque n rotational speed of the cage of the planetary gear P power P A accumulator power P E electric power P F saw frame power P 0 power rating PCS power control system P CA charging power of the accumulator P D driving power P DA discharging power of the accumulator P M motor power P R recuperation power PG planetary gear r radius r 1 radius of the counterweight placing RG reduction gear R P amplitude value of the ground work reaction Dm S mass of extra saw blades which cause imbalance u angular displacement of the electric motor shaft _ u u angular speed of the cage of the planetary gear _ u u P 1 amplitude value of the angular speed of the driving motor shaft u 1 angular displacement of the electric motor shaft x 0 motor angular speed IntroductionIn frame sawing machines a saw frame cyclic motion produces an inertial force, which is the cause of many serious usage difficulties for these machine tools i...

Cutting model parameters from frame sawing of natural and impregnated Scots pine (Pinus sylvestris L.)

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Effect of the Drying Method of Pine and Beech Wood on Fracture Toughness and Shear Yield Stress

“…Experimental cuttings were performed on the PRW15M sash gang saw with a hybrid dynamically balanced driving system and elliptical teeth trajectory movement. The concept of the machine was developed at Gdańsk University of Technology [ 45 ] and prototype manufactured by REMA S.A. (Reszel, Poland). The use of electric power (active and passive) during idling and working cycles was continuously monitored with the power converter PP54 (LUMEL S.A., Zielona Góra, Poland).…”

Application of fracture mechanics for energetic effects predictions while wood sawing

“…The indispensable raw material data for computation such as fracture toughness R \ = 840 Jm -2 and the shear yield stress s c\ = 22,636 kPa were determined according to the methodology described in the works by Orlowski and Atkins (2007) and Orlowski and Palubicki (2009). The latter data determination tests of raw material were carried out on the sash gang saw PRW15 M (Wasielewski and Orlowski 2002;Orlowski 2010) with stellite tipped saw blades with a kerf equal to S t = 2 mm. The average density of samples was q = 525 kgm -3 at moisture content MC 8.5-12 %.…”