Simulation of Flat Die Deep Drawing Process by Variable Contact Pressure Sliding Model

Influence of the contact pressure in the deep drawing processes is a very actual research topic in the metal forming technology. Within this research the tribological model of the strip sliding in the flat die was developed. The original experimental computerized apparatus for testing of the strip sliding in the variable contact pressure conditions was developed, as well. The complex, multi-factor experiment was performed by application of the Al thin sheet, with the contact elements of various roughnesses, with different lubricants application and with the variable contact pressure. Besides the description of the developed apparatus, the theoretical way for determination of the pressure dependences was also presented. Based on the theoretical changes of pressure, set in advance, the real influence of the contact pressure was obtained, for each of the given conditions. That makes possible to determine the influence of the tribological factors on the actual pressure. The obtained real contact pressure has verified the reliability of the experimental apparatus, namely the degree of the theoretical pressure dependences deviation from the real ones

Selection of the most appropriate welding technology for hardfacing of bucket teeth

A possibility of extending the service life of the working parts of construction machinery with particular attention to hardfacing of loader bucket teeth was investigated. In the first part of this paper the tribological processes typical for this machinery is analysed. Worn excavator parts are made of conditionally weldable cast steel that requires a special hardfacing technology, so numerous investigations were performed to obtain the most appropriate technology. In the experimental part of the paper, the selection of the optimum hardfacing technology for bucket teeth and the procedure of the manual arc hardfacing are presented. The samples were first hardfaced using different techniques and technologies and then the microstructure and microhardness of characteristic hardfaced layers were studied. Specially prepared samples were used for tribological investigations. The results of experimental investigations enabled the selection of the most suitable hardfacing technology and its application to real parts. The bucket teeth, with their hardfaced layers applied vertically, horizontally or in a honeycomb pattern were mounted onto a loader bucket, alternated with the new non-hardfaced teeth and their performance during the operation was regularly monitored. After a certain period, the degrees of the wear for the non-hardfaced and differently hardfaced teeth were measured. Taking into account both technical and economic factors, the most suitable hardfacing technology was determined

Selection of the most appropriate welding technology for hardfacing of bucket teeth

A possibility of extending the service life of the working parts of construction machinery with particular attention to hardfacing of loader bucket teeth was investigated. In the first part of this paper the tribological processes typical for this machinery is analysed. Worn excavator parts are made of conditionally weldable cast steel that requires a special hardfacing technology, so numerous investigations were performed to obtain the most appropriate technology. In the experimental part of the paper, the selection of the optimum hardfacing technology for bucket teeth and the procedure of the manual arc hardfacing are presented. The samples were first hardfaced using different techniques and technologies and then the microstructure and microhardness of characteristic hardfaced layers were studied. Specially prepared samples were used for tribological investigations. The results of experimental investigations enabled the selection of the most suitable hardfacing technology and its application to real parts. The bucket teeth, with their hardfaced layers applied vertically, horizontally or in a honeycomb pattern were mounted onto a loader bucket, alternated with the new non-hardfaced teeth and their performance during the operation was regularly monitored. After a certain period, the degrees of the wear for the non-hardfaced and differently hardfaced teeth were measured. Taking into account both technical and economic factors, the most suitable hardfacing technology was determined

Theoretical and experimental estimation of the working life of machine parts hard faced with austenite-manganese electrodes

We have investigated the possibility of repairing damaged machine parts by hard facing with austenite-manganese steel electrodes. The subject is a Fe-C-Mn alloy with a microstructure of soft austenite which, after cold deformation, transforms by a shearing mechanism into a hard martensite microstructure. These steels are used mainly for parts exposed to high impact loads and intensive abrasive wear. Depending on the degree of wear, these parts can be replaced by new ones or repaired by hard facing. The selection of the optimal reparation technology for the rotational crusher's impact beams is the subject of this study. Investigations of model samples were conducted first, followed by layers hard faced onto samples with austenite manganese and special electrodes. After this the microstructure and hardness of the welds' characteristic zones were investigated. After reparatory hard facing the impact beams were mounted in the crusher and their behaviour was monitored periodically. Both the new and hard-faced beams' behaviours were monitored and compared under the same working conditions. In this way, the optimal technology for hard facing was established, taking into account not only the technical indicators, but also the economic effects

Theoretical and experimental estimation of the working life of machine parts hard faced with austenite-manganese electrodes

We have investigated the possibility of repairing damaged machine parts by hard facing with austenite-manganese steel electrodes. The subject is a Fe-C-Mn alloy with a microstructure of soft austenite which, after cold deformation, transforms by a shearing mechanism into a hard martensite microstructure. These steels are used mainly for parts exposed to high impact loads and intensive abrasive wear. Depending on the degree of wear, these parts can be replaced by new ones or repaired by hard facing. The selection of the optimal reparation technology for the rotational crusher's impact beams is the subject of this study. Investigations of model samples were conducted first, followed by layers hard faced onto samples with austenite manganese and special electrodes. After this the microstructure and hardness of the welds' characteristic zones were investigated. After reparatory hard facing the impact beams were mounted in the crusher and their behaviour was monitored periodically. Both the new and hard-faced beams' behaviours were monitored and compared under the same working conditions. In this way, the optimal technology for hard facing was established, taking into account not only the technical indicators, but also the economic effects