PSI - Issue 13

Filip Miletić et al. / Procedia Structural Integrity 13 (2018) 1644 – 1650 Author name / Structural Integrity Procedia 00 (2018) 000–000

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optimization of buckets and teeth is the knowledge of the influence of digging parameters, more precisely the parameters of the cut, which are (thickness of the cut, width, their relationship) of the digging process. The third step is the knowledge of the construction parameters of the excavator. By knowing these parameters and analyzing the cutting geometry, optimal cutting geometry can be achieved. 2. Cutting elements on rotor excavators Depending on the materials to be excavated, the buckets are equipped with knives, angular blades or teeth. Buckets with a knife are used for soil excavation with very low resistance to cutting. For solid materials, buckets are equipped with individual teeth in the most loaded places. The teeth is an element of a bucket that has a dual role in the digging process: the destruction of the basic material and the excavation of that material. Its geometric and mechanical properties must match the requirements, conditioned by the technological process and the type of cutting material. By using the teeth, the available cutting force concentrates on a small cutting length, and thus facilitates the penetration of the bucket into the material. The teeth must satisfy several requirements, of which the most important are: favorable geometry from the aspect of cutting, high wear resistance and high mechanical strength. 2.1. Wear of cutting elements Teeth wearing depends on the properties of the material to be digested, the resistance of the teeth material to wear as well as the operation of the excavator. In this case, the teeth are exposed to the combined effect of abrasion and shock, which are manifested through rapid tooth loadings during the operation of the excavator. This leads to the progressive wear of the tooth material, and in severe cases to its deformation or fracture. Then the teeth cannot properly perform its basic function, which directly and indirectly reflects the capacity, load and power consumption of the excavator. The process of wearing cutting elements, in addition to the material that is being excavated, is influenced by a number of other factors, such as:  material from which the cutting elements are made; In the digging process, material is slid through the cutting elements, resulting in unwanted wear of the teeth. The wear process reflects the geometrical characteristics of the cutting elements, their lifetime and general usability, and indirectly to the capacity of the rotor excavator, the energy consumption and the general readiness of the excavator for normal exploitation. It is obvious that the wear phenomenon has a major impact on the drive readiness and reliability of the rotor excavator, so it needs to be carefully studied both from the aspect of the cause and preventive action in the same way in the field of remediation and removal of possible consequences. Through practice and field testing, it is known that increased wear on teeth in the buckets of rotary excavators, as a consequence:  increased digestion resistance;  the specific performance of the excavator is reduced [t/h];  increased machine vibration;  increased specific energy consumption; Exploitation conditions for the teeth on the rotor excavator that are in direct contact with the working environment that is being excavated are very difficult and complex. Wearing depends primarily on the properties of the material to be digested, the resistance of the tooth material to wear or, more precisely, the constructive adjustment of the teeth to the digging conditions on a concrete surface mine. In this case, the teeth are exposed to the combined effect of abrasion and stroke, which are manifested through the bursts of teeth load during the operation of the excavator. Shown in figure 1 are the cutting elements of the excavator SRs - 2000.32 / 5, which is engaged on the surface mine Tamnava – West field, in the Kolubara basin.  constructive characteristics of teeth;  rotor excavator operating mode and  specific digging resistant.  increased maintenance costs and  reduced reliability of the excavator.