Optimizing the Sharpening Process of Hybrid-Bonded Diamond Grinding Wheels by Means of a Process Model

The grinding wheel topography influences the cutting performance and thus the economic efficiency of a grinding process. In contrary to conventional grinding wheels, super abrasive grinding wheels should undergo an additional sharpening process after the initial profiling process to obtain a suitable microstructure of the grinding wheel. Due to the lack of scientific knowledge, the sharpening process is mostly performed manually in industrial practice. A CNC-controlled sharpening process can not only improve the reproducibility of grinding processes but also decrease the secondary processing time and thereby increase the economic efficiency significantly. To optimize the sharpening process, experimental investigations were carried out to identify the significant sharpening parameters influencing the grinding wheel topography. The sharpening block width lSb, the grain size of the sharpening block dkSb and the area-related material removal in sharpening V’’Sb were identified as the most significant parameters. Additional experiments were performed to further quantify the influence of the significant sharpening parameters. Based on that, a process model was developed to predict the required sharpening parameters for certain target topographies. By using the process model, constant work results and improved process reliability can be obtained.

EFFECTS OF GRINDING WHEEL WEAR ON THE THERMO-MECHANICAL LOADS IN THE GRINDING PROCESS

A large amount of the energy produced during grinding is converted into heat. Since not all of the heat can be dissipated by the cooling lubricant, thermally induced displacements in machine components occur, which has a negative influence on the component quality. The generation and distribution of heat is influenced by the change of the grinding wheel topography due to wear.Therefore, the wear mechanisms of grains were identified and quantified and their effect on heat generation was investigated. For this purpose, creep feed grinding investigations on bearing steel were conducted with electroplated CBN grinding wheels with different grain specifications.

Evaluation and investigation of grinding process of biomedical polymer (PEEK)

Polyether ether ketone (PEEK) has been widely used in the medical engineering due to its high strength to weight ratio, creep and wear-resistance, and anti-allergically properties. Grinding is generally used to produce PEEK parts with high accuracy and surface quality requirements. In this research, the tool loading and the effect of cryogenic cooling in the grinding of PEEK are studied for the first time. It is shown that the generated heat in the grinding process, which is mainly influenced by the tool micro-topography, process parameter, and coolant lubricant has an important role in the surface integrity of PEEK. Additionally, the influence of specific material removal rate and the dressing speed ratio on the specific grinding energy of PEEK was studied. The input parameters of the grinding process that are investigated in this study include cutting speed (vs), depth of cut (ae), and feed rate (vft). To investigate the grinding wheel topography, the effects of dressing overlap ratio (Ud) and the dressing speed ratio (qd) were also investigated. Grinding force, surface roughness, and loading of the grinding wheel were considered as output parameters. The experiments were designed based on response surface methodology and the optimum cutting condition was obtained based on this method. The depth of cut and the dressing overlap ratio had respectively the maximum and minimum impact on the surface roughness and cutting forces. Additionally, the tool loading was mainly influenced by the cutting speed.

Kornbruchverhalten beim Abrichten von CBN/Fracture behavior of CBN during dressing – Analysis of the single grain dressing process of CBN

Die Schleifscheibentopographie, welche durch den Abrichtprozess erzeugt wird, ist ein wesentlicher Einflussfaktor für das Prozessergebnis beim Schleifen. Das Bruchverhalten der Kornwerkstoffe beim Abrichten hängt nicht nur von den Abrichtparametern, sondern auch von dem Korntyp der Schleifscheibe ab. Daher wurden Abrichtversuche an einzelnen CBN-Körnern durchgeführt, um den Einfluss der Abrichtparameter und des Korntyps auf das Prozessergebnis zu ermitteln.   The grinding wheel topography generated by the dressing process is a factor of major impact on the result of the grinding process. The fracture behavior of the grains of the grinding wheel during dressing not only depends on the dressing parameters but also on the grain type of the grinding wheel. Therefore, dressing tests of single CBN grains were conducted to determine how the dressing parameters and the grain type influence the process result.

Some Experimental Aspects of Grinding Soft Steel Under Different Machining Conditions

In this study, the effects of dressing parameters, wheel topography and machining environment on grinding performance of soft steel are investigated. To generate different grinding wheel topographies, dressing speed and depth have been changed during dressing of vitrified Al2O3 wheels using single point diamond dresser. After dressing of grinding wheels, machining tests have been conducted to study the influence of the wheel topography and coolant-lubricant types on the performance of grinding operation. The results suggest that MQL is more suited to grinding of soft material in the finishing step (shallow cut) with the finest dressing than wet and dry grinding.

Prediction of Ground Surfaces by Using the Actual Tool Topography

This paper presents a prediction model for ground surfaces that uses the actual grinding wheel topography to perform a grinding simulation. Precise knowledge of expected machined surfaces plays an important role in process planning. Here, the main criterion is the achievement of the components’ function after manufacturing. Therefore, it is essential to consider the surface roughness to enable a function-orientated workpiece surface. The presented approach uses a real grinding tool topography, which is measured by a 3D laser triangulation sensor in the machine tool. After a data processing step, the measured topography is imported into a material removal simulation. A kinematic simulation of the realistic ground surface enables the data-based confirmation of the envelope profile theory for the first time.