EXPERIMENTAL RESEARCH INTO THE WORK OF A WRENCH GRAPPLE AT OAO "STROIKERAMIKA
The improvement of load gripping devices of the load-lifting machines used in construction is in the foreground of research and has important practical application. The research aims to check the performance and reliability of the modernized winch grapple, to determine its main characteristics and parameters, as well as to identify the causes of its early failure. The authors provide recommendations on how to reduce the operation time of the machine and increase its durability. The research addresses the following tasks: the determination of bulk density of сlay in different seasons; the study of the scooping capacity of the grapple; the loading timing necessary to scoop clay from the pit and unload into a storage bin or onto a transportation device; the measuring of the power of the wrench in the working and idle modes; definition of the working force in a rope, the effectiveness of the grapple and operating mode of the crane equipped with a grapple. The authors describe the methodology of the experimental studies used when addressing the set tasks. The reliability of the results is achieved due to processing the experimental data by means of variation statistics. In order to determine the bulk density of clay and the scooping capacity of the grapple, we used the method described in [5]. A simpler method in comparison with the recording onto a strip-chart power recording device was used to determine the scooping capacity of the device. When determining the working force in the runner we also used a simpler method, as compared to the tensometric method, which was used earlier in the study of the hoisting grapple [5]. The latter has significant drawbacks and is not suitable for the use in existing industry with a continuous work cycle. One of understudied issues is the coefficient of efficiency of a grapple, which tends to be estimated imprecisely. Therefore, the knowledge of the accurate value of this coefficient is very important. This value was experimentally determined. The knowledge of the operating mode of a crane with a grapple in particular operating conditions is vitally important. The operation of the crane with a grapple in a more intensive mode than the one specified in its instructions manual is forbidden by the Cranes regulations [6], because it leads to the reduction in reliability, service life, increases the failure rate, etc. The research proved the compliance of the real operating conditions (mode of operation) with the Instruction manual of crane operation. In general, the replacement of the electric hoist with the wrench proved to be efficient. The wrench mounted onto the grapple turned to be more reliable and more durable. The rope and block system is less reliable than the one in the traveling grapple mainly due to unaccounted overloads and operating conditions. The authors conclude by estimating the wrench grapple and suggest the recommendations on eliminating the identified shortcomings and enhancing the reliability and service life of the grapple.