Abrasive belt grinding is composed of abrasive belt, contact wheel, tension wheel, workbench and other basic components. The function of the contact wheel is to control the contact pressure of the abrasive belt particles on the workpiece and make the abrasive belt particles cut. The tensioning wheel plays the role of tensioning the sand belt. It is a roller made of cast iron or steel. Next, this paper will introduce the mechanism and characteristics of abrasive belt grinding of mechanical parts.
1、 General mechanism of abrasive belt grinding
The function of the contact wheel is to control the contact pressure of the abrasive belt particles on the workpiece and make the abrasive belt particles cut. The contact wheel is usually made of steel or cast iron with a layer of hard rubber poured on it. The harder the rubber is, the higher the metal removal rate is, and the softer the wheel surface is, the lower the grinding surface roughness value is.
The tensioning wheel plays the role of tensioning the sand belt. It is a roller made of cast iron or steel. When the tension is large, the grinding efficiency is high. Because the abrasive grains of the abrasive belt are arranged neatly and evenly, with small negative front angle and large rear angle, and the abrasive grains can participate in cutting at the same time, it has high efficiency, less grinding heat generation and good heat dissipation effect.
Similar to wheel grinding, the formation of chips also has three stages: elastic friction deformation, scoring and cutting. However, due to the above advantages, the surface residual stress and work hardening depth of grinding workpiece are much lower than that of wheel grinding.
2、 Characteristics of abrasive belt grinding
1. Abrasive belt grinding has high efficiency and high metal removal rate. Its efficiency has reached 10 times that of milling and 5 times that of ordinary grinding wheel.
Due to less heat generated by friction and long heat dissipation interval of abrasive particles, it can effectively reduce workpiece deformation and burns, which is known as "cold" grinding. Generally, the machining accuracy can reach the machining accuracy of ordinary grinding wheel grinding, and some dimensional accuracy can reach ± 0.005mm, the maximum can reach 0.0012mm, and the flatness can reach 0.001mm.
2. The abrasive belt is in flexible contact with the workpiece, which has good running in and polishing effects, and can grind all kinds of complex forming surfaces. The surface roughness of the workpiece can reach 0.8-0.2 microns.
3. It has strong adaptability, and can be used in ordinary lathes, vertical lathes, gantry planers, etc. to grind external circles, internal circles, planes, etc. with abrasive belt grinding heads.
4. The equipment structure is simple. The contact wheel is rarely worn, which can keep the sand belt at a constant speed; The transmission chain is short, which increases the stability of grinding, and the power utilization rate of the machine tool is more than 85%.
6. The auxiliary time is less. After the workpiece is positioned once, the abrasive belt can be replaced many times to complete all processing, without balancing and dressing like the grinding wheel.
7. It is easy to operate, convenient to maintain, safe and reliable, and the machine tool has high seismic resistance.