Advanced grinding technology

Author: Chief Editor: Jing Hongzhi
Publisher:
Publish Date: 2004-07-01
Features:
Fragment: To understand the principles and applications of CNC grinders, be familiar with the characteristics of new grinder structures such as hydrostatic bearings, and understand the features and applications of superhard grinding tools. Section 1: CNC Grinders
1. Overview of CNC Machines
CNC machines are high-efficiency automated tools that use digital control devices or computers for control. They integrate advanced technologies from automatic control, computing technology, precision measurement, and machine tool structures. With the development of science and technology, the shapes and structures of mechanical products are continuously improved, and the requirements for part machining quality are also increasing. The proportion of single-piece and small-batch production of mechanical products is growing, especially in aerospace, shipbuilding, and defense industries, where many parts require low batch production, high precision, and complex shapes, making them unsuitable for large-scale automated machine tools, combination machine tools, and automatic lines used in industries such as automobiles and tractors. General machine tools are also difficult to meet the machining requirements. In this context, CNC machines have emerged and developed, effectively adapting to the needs of automated production with constantly changing, multi-variety, and small-batch products.
1.1 Characteristics of CNC Machines
CNC machines perform various operations required for machining, such as loading and unloading workpieces, tool feed, retracting, speed change, start/stop, and cutting fluid supply, by converting input commands into machine operations through the calculation of a dedicated digital computer. When the machining object changes, apart from re-clamping the workpiece and replacing the tool, only a pre-prepared control tape (punched tape, punched card, or magnetic tape) needs to be replaced to automatically machine the required workpiece without any adjustment to the machine, achieving high machining accuracy and production efficiency. Currently, CNC technology has been gradually applied to various types of grinders.
CNC grinders produced in China include:
- MGK1320A CNC high-precision external grinder, capable of grinding complex surfaces such as cams and drums, with roundness error of 0.0005mm and surface roughness of Ra0.01μm.
- MK2110 CNC internal grinder, used for grinding internal circles, internal concave faces, taper holes, and external end faces.
- MK9020 CNC optical curve grinder, equipped with a three-axis computer control system.
- MK2945 CNC vertical single-column coordinate grinder, with two-axis computer control.
- MJK1312 CNC simple external grinder, MK8532 CNC curve cam grinder, etc., all achieve high machining accuracy and have achieved significant benefits.
CNC machines also create conditions for computer-aided production management (PPC), computer-aided design (CAD), computer-aided process design (CAPP), and computer-aided manufacturing (CAM). By networking various types of CNC machines and controlling them with a more advanced computer, along with the use of industrial robots for automatic loading and unloading and devices for automatically conveying workpieces between machines (such as conveyors, trolley cars, or unmanned carts), multiple workpieces can be processed in the system according to different process flow routes. This flexible and adaptable automated production system capable of processing multiple products is called a flexible manufacturing system (FMS). Connecting all FMS systems with a higher-level computer forms an unmanned automated production workshop. Therefore, CNC machines have a broad development prospect.
1.2 Working Principle of CNC Machines
Machining parts on a CNC machine typically involves the following steps:
(1) Program design: Based on the requirements of the part drawing, determine the machining program, including the main spindle speed, feed speed, rapid approach or retreat distance, travel length, and other auxiliary movements of the machine in each program.
(2) Program sheet preparation: Divide the program into segments and compile it into a program sheet using codes (numeric, alphabetic, and symbolic) that the CNC device can recognize.
(3) Punched tape production: Punch holes on the tape according to the codes on the program sheet on a punching machine to create a punched tape.
(4) Punched tape photoelectric conversion: Place the punched tape into a photoelectric reader to convert the codes into electrical pulse signals, which are then input sequentially into the CNC device.