Abstract

Work with chain saws involves the risk of injury; workers wear protective equipment to protect themselves against these injuries. The question arises: How can the resistance of the protective equipment be evaluated? It can be evaluated either by using one of the test methods described in current standards or by using a new test method that has advantages over existing methods. The new test method is chosen because it measures the energy needed by a chainsaw to cut the protective equipment to be evaluated. The energy then becomes the performance criterion to classify the equipment and is an overall physical measurement parameter for evaluating the cut resistance of the material to a chainsaw.

In the test method developed, a motor drives a fly wheel that acts as an energy reservoir, which in turn drives the chain. Once the test velocity has been reached, the motor is disengaged and the flywheel becomes the only source of energy driving the chain. The chain then comes in contact with the protective equipment to be evaluated.

The total cut-through energy, selected as performance criterion, is determined by evaluating the difference between the initial and final kinetic energies of the rotating system. Also, a sensor installed between the flywheel and the chain records the torque transmitted by the flywheel to the chain. This method determines the energy dissipated when the equipment evaluated is being cut.

The test phase was used to validate the operation of the test bench and to verify the feasibility of the measurement principle. The energy dissipated during cutting was evaluated for different materials and under different test conditions.

The results obtained show that the energy necessary to cut through a sample is a repetitive measurement independent of the initial test velocity.

In contrast to existing test methods, the method developed is independent of the drive system used, and consequently the motor driving the flywheel can be replaced or undergo maintenance without affecting the results. This ensures that the test method will retain its precision over time.

References

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