The topography of the grinding wheel can be depicted in a control workpiece. For this purpose, a mirroring workpiece angled diagonally to the grinding direction is ground once. Counting the scratch marks, a conclusion can be drawn to the number of active cutting edges per unit surface area. Since the scratch marks of successive cutting […]
Рубрика: Handbook of Machining with Grinding Wheels
Segmented Wheels
Wheel manufacture of a high-speed segmented wheel consists of epoxy bonding or cementing a ring of vitrified CBN segments to steel core as shown in Figure 4.6. The segmented design serves several purposes. First, it produces a much more consistent product than a continuous or monolithic structure because of the limited movements required in pressing […]
Brown Alumina
The resultant abrasive is called brown alumina and contains typically 3% TiO2. It has a Knoop hardness of 2,090 and a medium friability. Increasing the TiO2 content increases the toughness but reduces hardness. Although termed brown, the high temperature furnacing in air required in subsequent vitrified wheel manufacture turns the brown alumina grains a gray-blue […]
Thermal Stability of Diamond
Diamond is metastable at room temperatures and pressures and it will convert to graphite given a suitable catalyst or sufficient energy. In a vacuum or in inert gas, diamond remains unchanged up Premium long stones Lower quality/processed long stones to 1,500°C; in the presence of oxygen it will begin to degrade at 650°C. This factor […]
Fracture Wear Mode of Vitrified Wheels
In addition to the size of the bond-bridge, the fracture mode is also critical. The bond must be strong enough to hold the grains under normal grinding conditions, but under higher stress it must allow the grain to fracture in a controlled way. The bond should not be so strong relative to the grit strength […]
Synthetic Needle Diamonds
The wear of single-point diamonds in profile dressing leads to problems with changing dress conditions because of the increasing cross section of the flat generated. The introduction of synthetic needle diamonds provides a solution in the form of a constant cross section. This type of tool has seen increasing usage as a replacement for higher […]
Dress Parameters for Form Rolls
This discussion will consider first the dressing of conventional abrasive wheels with form diamond rolls. This can then be extrapolated to include vitrified CBN. The dressing process entails plunging the roll into the wheel at a fixed infeed rate in mm/min or mm/rev of wheel at a fixed crush ratio followed by a fixed dwell […]
2.2.11 Grinding Power
Grinding power, P, can be estimated from the specific grinding energy, ec, using the equation P = e • Q ‘■ b c w where bw is the width of grind. 2.2.12 Tangential Grinding Force Tangential grinding force, Ft, may then be calculated from 2.2.13 Normal Grinding Force Normal grinding force, Fn, is related to […]
KINEMATICS OF THE CUTTING EDGE ENGAGEMENT
In order to compare a variety of grinding processes, it is necessary to define general and comparable process parameters. With these parameters, different processes can be compared with each other allowing an efficient optimization of the process. The most important grinding parameters are the geometric contact length, lg, chip length, lcu, and the chip thickness, […]
Abrasive Layer Depth
For thin segments, the major stress is circumferential, but for thicker segments the dominant stress shifts to radial. For this reason, an abrasive layer thickness of 10 mm maximum is typical for a high-speed wheel. This immediately places limitations on profile forms allowed. The key factor is the mass of the segment, and its impact […]