Electronic control hydraulic impactor based on pressure feedback
The impact energy of the traditional hydraulic impactor can be regulated manually between the second and the third grade, and its impact frequency can not be adjusted independently. Also, they have to stop working for adjustment. In order to alter this situation, a new hydraulic impactor DBS500, which controlled by micro-electronic system, has been designed and its functions are showed as following: The impact energy can reach 500 joules and its impact frequency also realizes regulation from 0 to 8Hz steplessly. It can estimate the work object's nature by piston's rebound behavior. It can self-regulate the impact energy and frequency according to the object's nature, so that can improve the working efficiency and adapt the power of the loader.
Hydraulic Impactor Control Methods and Charts
Abstract The authors discuss the approved advanced control charts for operational cycles of hydraulic impacting machines. These control charts allow adjusting operational characteristics of the machines either using only pressure back-coupling between the fluid power system and distributor, or in combination with introduced additional pressure control. The article describes adaptive impacting machines equipped with the control charts which allow adjustment of blow energy and frequency subject to properties of a medium being fractured. It is emphasized that to expand the application range of hydraulic impactors, it is required to design high-frequency percussion machines with high impact capacity owing to improvement of distributors and due to transition to the increased power fluid pressure.
Energy transfer in percussive rock destruction—III: Stress wave transmission through joints
Abstract Two different models representing a joint between drill rods are analyzed. The joint is first treated as an elastic swell and then as a rigid mass between two elastic rods. According to the rigid joint model, the joint is analogous to a simple low-pass filter. The efficiencies of stress wave energy transfer derived from the two models are shown to agree well in many situations of interest in hammer drilling, and since the rigid joint model leads to a simplified analysis, this model is used in solving two problems. First, for an incident stress wave of a given length, the pulse shape leading to maximum efficiency of energy transfer through a single joint is determined. This ideal pulse, which is represented by a symmetric portion of a half sine wave, is generally difficult to obtain in a practical situation. However, a rectangular pulse of the same length, which is easily generated by impact, leads to an efficiency which is never more than 0·04 lower than the efficiency for the ideal pulse. Secondly, stress wave energy transmission through an arbitrary number of joints is treated. The results show that when passing a joint, the stress wave is favourably modified with respect to further transmission. Measured transmitted stress waves agree well with theoretical results derived from each of the two models.