Abstract
The energy absorber is used to simulate the reaction of a working piece subjected to a vibration stimulus, by which the consistent and repeatable reactions to the tool’s vibration inputs could be achieved. According to the proposed coupling simulation model by using commercial software RecurDyn and EDEM, the energy dissipated by the energy absorber and the contact force between the drill rod and the piston are evaluated under different load conditions such as the impact frequency and impact stroke. Moreover, the effects of the ball diameter, ball column height, and diameter on the energy absorption characteristics are also studied. The results show that the impact frequency and stroke influence the energy absorber by changing the impact force; the energy absorption is more obvious under higher impact frequency and long impact stroke. The filling ball diameter influences the energy reflectivity by changing the porosity, which is negatively correlated to the energy reflectivity, and a 6 mm filling ball diameter is suggested. The energy reflectivity is inversely proportional to the ball column height and diameter, and the suggested ball column diameter and height are 160 mm and 600 mm, respectively, with energy reflectivity of 0.045. Even when the increase in impact frequency and stroke will increase the contact force, the dynamic load factor decreases. The contact force and dynamic load factor are inversely proportional to the ball column height, but they are not influenced by the ball diameter and the ball column diameter.
Highlights
Rock drilling machines are widely used to drill or break the rock and concrete in many areas, such as mining, railway, hydropower, and transportation engineering construction
Clarke et al fixed an accelerometer into the mounting block welded on the chisel to measure the vibration emitted by percussive tools, but problems such as the fracturing of the weld holding the block to the chisel, and the unscrewing of the stud holding the accelerometer to the block were encountered during the test [14]
Bitsch et al used six different energy absorption methods, which are the hydraulic base, the steel shot, the actual breaking of concrete, the AFNOR concrete block, and the pointed chisel embedded in concrete, to simulate the actual working condition in the handle vibration measurement of percussive tools, the results showed that the different methods tested were all valid and comparable to those obtained when real concrete was broken
Summary
Rock drilling machines are widely used to drill or break the rock and concrete in many areas, such as mining, railway, hydropower, and transportation engineering construction. Bitsch et al used six different energy absorption methods, which are the hydraulic base, the steel shot, the actual breaking of concrete, the AFNOR concrete block, and the pointed chisel embedded in concrete, to simulate the actual working condition in the handle vibration measurement of percussive tools, the results showed that the different methods tested were all valid and comparable to those obtained when real concrete was broken. They proposed that, for the steel shot energy absorption method, the box diameter should be at least 500 mm, and the depth of the shot should be 300 mm [15]. As the energy absorber provides very consistent working conditions for different subjects, requires little maintenance, and can be used repeatedly for the experiment, it is essential to understand the characteristics of the energy absorber and optimize its structure to satisfy the demand that the reflected energy should not exceed 20% of the incident energy [17]. is study investigates the energy absorption characters of the steel ball friction energy absorber and provides the relationship between the energy absorption efficiency and the structural parameters of the energy absorber
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