Air-leg rock drill handle structure assessment

2013-07-19 15:17:27

Drilling work long-term manipulation of Air-leg rock drill arm tremor susceptible to disease, thereby reducing efficiency and increasing economic losses. Therefore, scientific research workers are designed and tested to improve the drilling machine handle to minimize hand-arm vibration.

By the Canadian Mining Industry Research Organization sponsored a research program underway to determine synthetic rubber-coated steel lever handle instead of the standard results. In this study, developed a standard assessment of rock drill handle vibration measurement technology. Now able to determine the outlet leg rock drill vibrations transmitted to the arm strength, and the new design of the handle relative to the standard design reduces vibration intensity has also been measured out.

In this study, using two synthetic rubber coated handle to determine the effect of replacing standard steel handle. First, by using a synthetic rubber stiffness of the handle (durometer hardness of 70 Duro), called the plastic handle; Another is to use a large flexible handle made of synthetic rubber (durometer Duro 65), known as rubber handle.

Experimental results show that the plastic handle and rubber grip on the interface total acceleration levels were 60% lower than that of steel handles and 67%. This is mainly in the frequency range above 500Hz measured as the frequency increased, the performance will be improved. Drilling work on the qualitative assessment of such vibration handle that operate rubber handle much more comfortable to handle than steel.

The rubber grip test system using HD Dampcd E-lastomer material, its Douro Hardness of 56 and a diameter of 41. 3mm, and trailers equipped with friction grip, you can control the air pressure, which carried by the wind twisting the handle pressure in a controlled manner different from steel handle mounted on the handle end of a small wheel control.

Test mine is Brooklyn Hill nickel mine, Ona flat ore, Kidd Creek mine, Connor Strasser ore mines and opi semi-ska. A trial period of six months. Tests on rubber handle and steel handle vibration measurement techniques using the same kind of determination, also recorded the operator feelings and opinions.

The test method is to use a handle if the two kinds of different rock drilling machine to drill a series of different lengths, respectively, (1. 2m ~ l. 4m) of the hole. Cross drill only, the use of air pressure, pressure and water pressure are mine standard value, respectively 620kPa and 414kPa, also records the measured depth of the hole gas leg angle and the operator's arm position and the holding position. Operator shall be without gloves.

Direct recording, the tape recorder of the measurement system determines a frequency of 50 ~ 8000Hz, while recording a signal frequency is then taken as a starting point to 900Hz. All data recorded by tape record for later laboratory analysis conducted. For each test condition, the acceleration of about 45 seconds was recorded once, because only two channels each test for data logging and accelerometers using only two records, and must always be re-configured repeatedly measuring equipment and to obtain the desired test data on the three orientation. The vibration strength test, must complete six azimuth data combined measurement.

Vibration measuring vibration data logger records, according to the international standard IS05349-1986 (E) seems to decibel units as acceleration as Hertz unit of frequency.

Table 1 lists the steel and rubber grip handle in the field test measuring total average results of the vibration intensity. These data were from five mines, 85 separate trials and from the initial installation handle to six months after the test results. Table 2 summarizes the steel with a rubber grip handle is replaced by the total average relative decrease vibration intensity values.

At a frequency of 0 ~ 2000Hz and obtained within the range 0 ~ 8000Hz narrow-band frequency spectrum. Differentiate all spectral lines are 400 and has a five collections are averaged.

Terms of total vibration intensity, the rubber handle on the interface greatly reduce overall vibration intensity. In the high frequency range, the total for each axis direction vibration intensity decreased lOdB, indicating that the vibration transmitted to the arm 67% reduction in strength. The low frequency range, the vibration intensity decreases 5dB, y coordinate position in the lower lOdB, which proves that the rubber handle good effect is to reduce the high frequency vibration key.

Six months after the measurement results with the initial measurement result no significant change in performance, if there is a change, but the performance is slightly improved, although this is not much statistical significance.

Narrow channel frequency analysis for the assessment of that total rubber handle reduces vibration intensity of high-frequency vibration strength is mainly due to reduced component. In general, a significant reduction in the acceleration component primarily in the range above 500Hz.

Drilling work on the rubber handle qualitative assessment that the operation to be comfortable than steel handle many, but the test does not indicate the absolute advantage rubber handle, the structure would have to be a lot of improvements.

Air-leg with a motorcycle handle control the wind turns the practice has been adopted, but also better than the standard thumb wheel control. The reaction of mine are very slippery handle, in order to ensure safe operation shall be covered with non-slip material, and should be equipped with a cap to reduce hand twist.

Also found in the handle and wind pipe joints gap exists, the handle too easily nipped fingers, should be under the exhaust air port, in order to avoid facing the operatives exhaust. Overall, the handle is too large, it should be whittled big end tapered in order to hand when opening the eyes aligned with the axis of the drilling machine. The same time as the handle diameter is too large, it is difficult to opening the eyes. The size and structure of the rubber handle should be the same as the steel handle.

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