Grinding is currently one of the primary machining methods for semi-finishing and finishing, and grinding wheels are crucial tools in this process. Grinding wheels are typically used on surface, external, and internal cylindrical grinders, and can also be mounted on grinding machines to sharpen tools. Grinding wheels are manufactured in various shapes and sizes depending on the intended use, grinding method, and grinding machine type. Commonly used grinding wheels include straight grinding wheels, cylindrical grinding wheels, double-bevel grinding wheels, cup grinding wheels, bowl grinding wheels, and dish grinding wheels. Depending on their size, straight grinding wheels are used for cylindrical and internal grinding, surface grinding, centerless grinding, tool grinding, thread grinding, and grinding machines.
Cylindrical grinding is primarily performed on cylindrical grinding machines and is used to grind the external cylinder, external cone, and shoulder end faces of shaft-like workpieces. During grinding, the workpiece rotates at a low speed. If the workpiece simultaneously undergoes longitudinal reciprocating motion, with the grinding wheel feeding laterally relative to the workpiece after each single or double stroke of the longitudinal motion, this is called longitudinal grinding. If the grinding wheel width is greater than the length of the surface being ground, the workpiece does not move longitudinally during the grinding process. Instead, the grinding wheel continuously feeds laterally relative to the workpiece. This is called plunge grinding. Generally, plunge grinding is more efficient than longitudinal grinding. If the grinding wheel is trimmed to a formed surface, plunge grinding can process formed external surfaces.
Common straight grinding wheel cylindrical grinding methods are:
1. Longitudinal grinding has low grinding efficiency, but provides excellent surface quality and low roughness.
During grinding, the high-speed rotation of the straight grinding wheel is the primary motion, while the rotation of the workpiece, the reciprocating longitudinal motion of the worktable, and the periodic intermittent transverse feed of the grinding wheel constitute the feed motion. After each longitudinal or reciprocating stroke, the grinding wheel makes a transverse feed, and the grinding stock is removed through multiple transverse feeds.
2. Horizontal grinding, also known as plunge grinding, offers high grinding efficiency, but also results in high grinding forces and temperatures, necessitating an ample supply of coolant.
During grinding, the high-speed rotation of the straight grinding wheel serves as the primary motion, while the workpiece's rotation and the continuous horizontal feed of the grinding wheel serve as the feed motion. The worktable does not undergo longitudinal feed motion. The grinding wheel is wider than the width of the grinding surface and is fed slowly until the desired size is achieved.
3. Composite grinding combines longitudinal and transverse grinding, offering the advantages of both transverse grinding's high efficiency and longitudinal grinding's high quality.
During grinding, the workpiece is first rough-ground in sections using transverse grinding, leaving a fine-grinding margin for each section, with a certain amount of overlap between adjacent sections. Finally, longitudinal grinding is used for fine grinding.
4. Deep Grinding: This method offers high productivity, but the straight grinding wheel dressing is complex and requires the workpiece structure to ensure sufficient cutting depth for the grinding wheel.
During grinding, the grinding wheel is dressed to create a tapered or stepped surface on one end. Both the circumferential and longitudinal feed rates of the workpiece are very slow, and the entire stock removal is removed in a single longitudinal feed.
