Skäreggars spontanhaverier

Summary, in English

Disturbances in production caused by rupture, cracking and chipping of tool edges are only studied to a limited extent in comparison with the effect of the cutting edge wear. These phenomena are of increasing importance when automation in production is considered. This thesis deals mainly with the deterioration of cutting edges emanating from other sources than wear. By studying the non-wear-related deterioration behavior of cutting tools new ways are found to reduce the related disturbances in production.

\"Spontaneous break-down\" means that the cutting edge instantaneously does not fulfill its task any longer. By determining the balance between the acting load distribution and the response due to the tool properties, the probability of \"spontaneous break-down\" is judged. The guiding factors are principally revealed by cutting tests. The total response effect of the cutting edge properties cannot be determined without considering the load distribution at the same time.

Theories and measuring methods are developed which enables to study the balance between the load distribution and the cutting edge property behavior. The load distribution and the property behavior have been determined under well defined conditions, which give the possibility of predicting \"spontaneous break-down\".

The theories put forward may be used to develop tool materials and edge geometries and to judge the machinability of the work material.

The results obtained are used as a basis for developing tool monitoring systems. Further research should be directed towards analysis of the three-dimensional load distribution and also to the study of transient temperature- and stressfields.