ON THE ISSUE OF ENSURING SAFETY AT THE USAGE OF CIRCULAR SAW EQUIPMENT
The paper considers the issue of ensuring safe operation of circular sawing equipment for longitudinal sawing of wood. The relevance of the issue is dictated by the high level of injuries on this type machines, including fatal ones. The main traumatic factor is the reverse ejection of a billet, which is due to the peculiarities of mechanical processing of wood, namely, using a counter-sawing scheme, in which the feed resistance forces are quite significant. The probability of reverse ejection of the work-piece increases when wedging knives are absented or when trying to change the position of the work-piece during processing. To reduce the risk of service personnel injury circular sawing machines use counter-throwers (claw curtains). The paper considers the requirements of technical regulations for the jam angle of claw curtains and demonstrates a significant discrepancy in the recommendations. A mathematical expression that characterizes the condition for claw curtain trigger and capture of a workpiece is obtained. It is established that the main factors affecting of the claw curtain efficiency are: the coefficient of friction between a workpiece and a table, the coefficient of friction between a claw curtain and a surface of the workpiece and the jam angle. The paper studies the influence of each of these factors and builds graphical dependencies that allow us to visually assess the nature and degree of influence each of them. The influence of the jam angle on the sum of the friction forces is studied. Measures to improve the efficiency of claw curtains are proposed. However, the presented work is not exhaustive in this direction, since the jamming condition was recorded for the blunted edge of the counter-throwers and does not take into account the possibility of intrusion the claw curtains in the processed material, which is a promising direction for further research.