he structure of sander belt
Based on the analysis of material mechanics, the overall mechanical strength of an object is homogeneous, and its physical and chemical properties should be similar. The mechanical strength of objects composed of more than two units of the same material should be no less than the overall mechanical strength. The same is true for a belt, the joint is the weakest link of the belt under the action of external force. In the production process, the joint of the abrasive belt is the focus of the process technology work, because it is directly related to the use of the abrasive belt. Because it is necessary to fully consider the flexibility of the belt joint and the joint strength at the joint, mainly the tensile strength of the joint, that is, the impact on the contact wheel or the pressure plate at the joint, leaving the workpiece due to cycle Vibration marks produced by the grinding vibration until fracture occurs. The joint glue used in the joint is not firmly bonded or is sensitive to the medium due to heat, and it may fail and break. Therefore, abrasive belt joints must have the following properties: fracture resistance, that is, tensile strength and shear strength; high heat resistance and corrosion resistance of the medium; the thickness of the joint is not much different from that of the non-joint. When the tolerance is negative (the joint is lower than the non-joint) to maintain the necessary mechanical strength, especially the fine-grained abrasive belt should pay more attention to its mechanical strength. The evaluation of joint quality mainly uses two indicators, namely strength and thickness. The strength of the joint mainly depends on the quality of the joint glue and the joint process. At the same time, the strength of the sander base itself also has a certain influence. The tolerance between the joint thickness and the joint thickness must be determined by the quality of the glue and the quality of the base material, especially when there are negative tolerance requirements. The form of the joint determines the structure of the abrasive belt.
a. No joint abrasive belt. Jointless sanding belt is a kind of jointless sanding belt made by using simple cloth as the base of the sanding machine and going through a series of processes such as original cloth treatment, gluing, planting and curing. This kind of abrasive belt is an early product until today, only in Japan and my country (including Taiwan) still retain this product (a small amount). Due to the limitations of the tube cloth sanding machine substrate, production equipment and technology used in this kind of belt, it cannot meet the requirements of many specifications in the current market, especially wide belts, and the production efficiency is low and the process is complicated. Therefore, in modern belt production After being scoured for the second time, the noodles are replaced by the step belts with joints, and the joint sand belts are divided into lap joints without joint second belts. The term “abrasive belt” in the abrasive belt standards at home and abroad actually refers to the joint sanding. Head and butt joints are two major categories. From the past lap joints to the butt joints, the technical belts accounted for more than 75% of the European and American belts. The directionality stipulated when the belt cost: the overlapping sand belt is at the two joints. According to the determined width requirements, the inclined edges are respectively ground and the joint glue is applied, and then they are overlapped with each other. The thickness after lamination, that is, the thickness of the joint should not be greater than 0.1mm of the thickness of the non-joint. The width of the joint can be adjusted between 8~15mm according to the size of the sanding belt. The angle of the joint should be adjusted in the range of 45°~85°, generally narrow sand The belt uses a smaller joint angle, which can increase the lap area and increase the lap strength. Wide abrasive belts generally choose larger joint angles to facilitate joint operation. This joint method is currently widely used at home and abroad, whether it is cloth base, paper base or even composite base. Butt-joining sanding belt is a sanding belt made by pressing the sand or cloth base surface pad with a pad material after two joint edges are joined together. Before jointing, first edging the front (sand surface) or back (cloth or paper) of the two joint edges. The thickness of the grind is equivalent to the thickness of the joint gasket, so as to ensure that the joint thickness is equivalent to the non-joint thickness. The joint thickness can be thinner than the non-joint thickness (negative tolerance) when the user needs it. The padding material of the joint is a reinforced polyester film, which has high strength and extremely low elongation. The angle of the joint is determined according to the orientation of the reinforcing fiber in the polyester film, and the orientation angle of the reinforcing fiber is selected in the range of 45°~85 according to the joint angle of the abrasive belt.
Butt-joining is also a widely used jointing method. It is simpler in process than lap jointing. At present, the high-strength polyester film of butt-joining method in my country is all dependent on imports, so its use has been greatly affected. The butt joint method is divided into two forms: one is the general butt joint, that is, the direct splicing of the two joints (or flat joint); the other is the S-shaped butt, that is, the two joints are processed into S-shaped sides, and then the two The two S-shaped edges are bitten together like gears, and a polyester film is added to form an abrasive belt.
Post time: Aug-19-2020