| Mechanical mining excavator has the characteristics of large bucket capacity, high production efficiency and stable working performance. It is the key equipment in large scale open pit mining. Bucket tooth mounted on the front end of the bucket is an important component of the excavator. In the mining process, bucket tooth directly contacts with rock, ore, sand and other materials. So bucket tooth is badly worn, and has a huge consumption. At present, the researchs on improving the wear resistance of the bucket tooth, mainly focus on the following aspects, such as: improving the bucket tooth material, changing the heat treatment, refining the manufacturing processes and other aspects, and have achieved certain results. However, the researchs on improving the bucket tooth’s resistance wear through the improvement of the bucket tooth shape are relative few. Most of them mainly come from practice and perceptual knowledge, and are lack of deep theoretical research. The gradually formed view "the more thick bucket tooth is, the more wear-resistant it is", invisiblly causes the increase in manufacturing costs. Therefore, it is necessary to analyse the wear of bucket tooth, and improve its wear resistance by improving the structure of bucket tooth. The work is supported by the national high technology research and development program(863 program)— "Development of 75m3 Large Scale Open Pit Mechanical Mining Shovel(NO.2012AA062001)".This article conducted research on the issue for the wear on bucket tooth of WK-75 mining excavator. Main research contents are as follows:First of all, on the basis of reviewing a large number of domestic and foreign relevant literature, research status at home and abroad of bucket tooth and the application of discrete element method in the design of bucket were summarized. The research idea of using discrete element method to analyse the wear of bucket tooth was proposed.Secondly, three dimensional parametric model of bucket tooth was established by using UG software. The force of bucket tooth was analysed during the mining process. The wear mechanism of bucket tooth under different working conditions was explored. And the formula of bucket tooth wear model under the condition of high impact was modified.And then, the ideal digging trajectory under the condition of the least digging resistance was obtained, through the motion principle analysis of mining excavator working device. This trajectory was fitted with uniformly variable motion in three directions. The maximum error between the fitted trajectory and the ideal trajectory was 3%. The feasibility of fitting was proved. The fitting could provide the motion parameters for subsequent wear simulation in EDEM software.Finally, the wear simulation model of bucket tooth was established in the EDEM software during mining materials process. The force, contact energy and wear depth of main parts on the bucket were compared and analyzed. Bucket tooth was proved to be the part on which the force was the biggest and the wear was most serious. It was consistent with the actual results to verify the correctness of the simulation model. Then through the wear analysis of bucket tooth, the wear distribution rule of bucket tooth was got, and the variable law of contact energy, wear depth as well as wear rate with time were obtained. On the basis of this, the influence of material properties and the structure of bucket tooth on the wear were analyzed. The structure of the bucket tooth was improved. After the improvement, the average wear depth of bucket tooth was changed from 2.8μm to 1.35μm, and the maximum force on bucket tooth was changed from 2.4×106N to 1.6×106N.This research work provides a reference for the structure design of bucket tooth, and has a certain significance for improving the overall production efficiency and economic performance of large mining excavator. |
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