Enhanced grinding performance by means of patterned grinding wheels

In this paper, a new and innovative method for the patterning of grinding wheels is presented. The patterns are machined with a patterning tool by using fly-cutting kinematics. By changing the patterning process parameters, different pattern sizes and densities can be machined in a flexible way. Surface and cylindrical grinding experiments show that grinding with patterned grinding wheels can significantly reduce process forces, grinding burn, and grinding power. The surface roughness increases because less active cutting edges remain when grinding with patterned wheels. But especially for roughing processes, the results show great potential for increasing the overall grinding performance. The final publication is available at Springer via http://dx.doi.org/10.1007/s00170-014-6579-8.DFGFAPES

Process design of the patterning process of profile grinding wheels

In production environment, grinding is often the last step along the process chain. At this step, the main share of the value chain is already manufactured. Correspondingly, the process result of this step directly influences the product quality. Thus, the avoidance of process induced damages is a major challenge in grinding. The major limiting factor in grinding is the thermal load on the workpiece, which leads to grinding burn and tensile residual stresses. This thermal load can be reduced, as previous fundamental studies have shown, by means of using microstructured grinding wheels. In this paper, the patterning process of profile grinding wheels is investigated with regard to the resulting geometry and the resulting grinding wheel topography. In detail, an analytical model is established and evaluated that enables a design of the patterning process of profile grinding wheels. The presented formulas describe the local depth and width of a pattern over its length of engagement. The influence of the inclination angle of the patterning tool and the profile angle of the grinding wheel on the resulting width and length of one pattern is investigated. Further influencing parameters on the size of a pattern that are investigated are e.g. the radius of the grinding wheel, the radius of the patterning tool, the corner radius of the patterning edge and the speed ratio between the grinding wheel and the patterning tool. In addition, grinding experiments were conducted to validate the process design. The results show a high correlation between the calculated and the resulting patterns on the grinding wheel as well as that a decrease in cutting forces can be achieved by this approach. When maintaining the workpiece and grinding wheel load, the productivity of the profile grinding process can be increased in this way

High performance peel grinding of steel shafts using coarse electroplated CBN grinding wheels

Grinding is widely known for its low material removal rates and high surface quality. However, recent developments in production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than 300 µm. These superabrasive CBN-grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined with turning processes before hardening and finishing the work piece by grinding. However, the turning process can be eliminated by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper explores the limits of grinding wheels using grains with a size of B602 during soft and hard machining in comparison to conventional B252 grains. It is shown that the use of coarser grains leads to lower process forces, higher (tensile) residual stress and higher surface roughness. Residual stress and surface roughness are of less importance as these grains are to be used mainly in roughing operations with ensuing finishing operations for the required surface properties. Over all investigations, especially in hard machining, neither grain nor tool wear was observed for the B602 grains, whereas the B252 tool was severely clogged during the experiments. Additionally, the grinding force ratio indicates that the coarse grain tools have not yet reached their productivity limit as it increases over all investigated feeds. This indicates improving tool performance with lower amounts of rubbing for increasing feed rate during hard grinding and shows the potential for the industrial use of higher feed rates with larger grains

Grinding with patterned grinding wheels

Grinding is one of the most important manufacturing processes, especially when high surface qualities have to be realized or if hard or brittle materials have to be machined. Often the grinding performance is limited by workpiece failure due to a high thermal load in the contact zone. Therefore structured or patterned grinding wheels are frequently used to reduce the thermal load in the contact zone. In this paper a new patterning method will be introduced by using a fly-cutting kinematic for the structuring process. In face grinding experiments the patterned grinding wheels showed great potential to enhance the overall grinding performance by significantly decreasing process forces and grinding burn. The reduction of the thermal load in the contact zone can be explained by an improved coolant flow through the contact zone, which was measured with a specially designed coolant collecting bin.DFGFAPES

Process design of a novel combination of peel grinding and deep rolling

Grinding is mostly considered as a finishing operation by which a high surface quality is achieved. An increase in productivity is therefore limited by maintained surface properties such as the roughness or tensile residual stresses. Thus, a roughing operation is inevitable followed by a finishing operation, while both operations are separated, leading to larger cycle times and process costs. In this paper, a novel process combination is investigated in which the roughing is done by grinding and the finishing operation by deep rolling within one tool setup. In this way, both processes are conducted parallel within the primary processing time. The objective of this study is the knowledge of the characteristics of this process combination with regard to the workpiece surface integrity. Therefore, shafts are ground in peel grinding with varying grinding wheel types and process parameters and subsequently machined with deep rolling. The process combination is evaluated with regard to the process forces and the resulting surface properties. In addition, experiments using the process combination were conducted in order to investigate the transferability of the results towards the process combination. By this approach, it was found that the surface roughness was reduced up to 80% by deep rolling showing the potential of the process combination. © 2021, The Author(s)

Process limits in high-performance peel grinding of hardened steel components with coarse CBN grinding wheels

Recent developments in the production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than lg > 300 µm. These superabrasive grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined by turning processes before being hardened and eventually finished by grinding. However, the turning process can be substituted by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper investigates the process behaviour of vitrified and electroplated grinding wheels with large grain sizes during the machining of hardened steel components. Process forces, wear behaviour and workpiece surface roughness are investigated for three different grain sizes, and the process limits of both bond types are examined. The investigations show that vitrified tools do not fully suit the demands for peel grinding process with high material removal rates since wear by bond breakage occurs. The electroplated tools on the other hand are capable of very high material removal rates. Their wear behaviour is characterized by clogging of the chip space if the process limit is reached. Even so, both tools outperform a standard hard-turning process in terms of process time by 74% and 94% respectively. This process time reduction in combination with the possibility to use the same (machine) tool to machine both soft and hard sections of a workpiece adds flexibility to current process chains

Improving the Design of Diamond Wheel for High-Speed Grinding

Grinding at high speeds is a complex process requiring specific tools for successful use. Rotational stresses during high-speed grinding can lead to failure if the wheel is not correctly designed. These results are extremely difficult to be obtained during a large number of field experiments due to the high cost of testing equipment. So, the article describes ways of improving the integrity of the body of the diamond grinding wheel for high-speed regimes using analytical approaches and finite element method