Bukhman O. Improving safety at work with pneumatic hand tools

Subject of investigation: pneumatic impact-action hand tools. Thesis objective: enhancing labour safety for dressers by reducing the levels of local vibration and regulating the temperatures on the surfaces of pneumatic impact-action hand tools. Research methods: theoretical and experimental methods were selected with account of the following: fundamental knowledge in the field of vibration processes; regularities of structure formation and physical-chemical transformations in composite materials; standard and original methods of studying the performance of epoxy-polymers; special methods (using a shaker) for determining vibration characteristics; author-suggested methods of determining the temperature characteristics on the surface of pneumatic hand tools; mathematical statistics and prediction methods. Theoretical and practical results: technical and technological solutions were developed and scientifically substantiated for developing low-toxic epoxy-polymer compositions with first-rate vibration absorption and other performance indicators. Experiments demonstrated that the developed compositions could be used as antivibration materials applied onto handles of pneumatic hammers to minimise the probability of vibration-caused diseases in workers by 50-70%; the methodology for estimating the probability of vibration-caused diseases due to local vibration was refined and used to evaluate the effectiveness of antivibration means. Research novelty: for the first time, it was shown that epoxy-polymer vibration-absorbing materials applied onto the handle of a pneumatic hammer could reduce the logarithmic levels of vibration velocity and acceleration in the low-frequency (8-16 Hz) and mid-frequency (20-125 Hz) ranges by 25-40 %. For the first time, experiments have yielded the regularities of temperature variation on the surface of a pneumatic hammer during work in places of contact with human hands. It was found that the surface temperature drops on the barrel of the hammer and its rate of decrease depends on the ambient temperature. It was also found that the temperature is unstable on the handle of the pneumatic hammer, and using an antivibration material decreases the temperature gradient from 1.5-2 °C to 0.5-0.8 °C due to conversion of vibration energy to heat. Implementation: antivibration materials are used at PJSC Turboatom (Kharkiv) in an experimental batch of pneumatic hand hammers with an antivibration handle. Application area: activities focused to labour protection of workers subject to the harmful effects of local vibration.