1, sand belt in the grinding process prone to problems and solutions
(1) The sand belt is too soft
This problem generally occurs in the sand belt of animal glue, especially in the rainy season, animal glue is easy to absorb moisture and become soft and sticky, therefore, in the rainy season or wet areas should choose semi-resin or full-resin binder production of sand belt. It is not appropriate to open the packaging of the sand belt of animal glue too early to avoid excessive moisture absorption. If possible, cool or dry the wet animal glue again, but the temperature should not be too high to avoid foaming or coking of the glue layer.
(2) abrasive is easy to dull, but not fall off
When grinding the abrasive belt, if the contact wheel is too soft, it is easy to appear that the abrasive surface does not fall off but is not sharp. If this happens, it should increase the grinding pressure or replace the harder contact wheel or replace the contact wheel with a wider gear or replace the contact wheel with a small diameter, or reduce the linear speed of the sand belt, etc., which can solve the situation of the sand surface is not sharp.
(3) Easy to remove sand, the base exposed
This is mainly because the abrasive particles are not strongly bonded, and the sand belt should be replaced. Or choose a softer contact wheel or a larger diameter contact wheel to increase the curvature radius of the sand belt and reduce grinding pressure, or choose a contact wheel with a narrower gear to improve the line speed of the sand belt.
(4) The abrasive layer is blocked
Mainly the choice of sand belt is not the right way, if the processing of paint, should choose a special coating of sand belt, such as processing aluminum alloy, stainless steel, copper and other soft metal materials, should choose anti-lubrication, anti-coolant water resistant sand belt, to resist water and moisture, grinding wood and its products, should choose black silicon carbide or brown corundum abrasive.
2. Precautions for storage of sand belt
Whether it is animal glue or all-resin sand belt, it will be affected by the climate and have a certain change, especially the influence of animal glue products, that is, or semi-resin, all-resin products because the matrix is plant fiber and has not been water-resistant treatment, it will also have physical changes under different climatic conditions. If it is stored for too long in a place with too much humidity in the room, it will absorb too much moisture and produce curling. The reason for the curling of the sand surface is that the degree of moisture absorption between the binder layer and the substrate is different, and the substrate has more moisture absorption, so it expands. If the moisture absorption continues, coupled with the temperature rise, mildew will occur, resulting in the sand belt can not be used. If the humidity of the place is too small, that is, the climate is dry, the water in the product is excessively distributed, and the fundamentals contract, so the product is easy to curl to the substrate surface. In severe cases, the product is brittle and easy to break. Therefore, emery cloth and other coated abrasives should be kept in a cool, dry, ventilated warehouse. The best storage conditions are temperature 15-20C indoor relative humidity 50-60%.
In addition, the product should not be unpacked too early before use, opening the bag, it is better to open with use, two days before the use of unpacking is appropriate. The packaged sand box should not be subjected to heavy pressure, so as not to cause the sand belt crease and cannot be used. Semi-resin, animal rubber belt, generally should not exceed one year. Full resin sand belt should not be more than two years. When the above time limit is exceeded, the sand belt should be checked again to confirm that there is no problem before it can be used.
Before use, the sand belt should be sent to the work site 2-3 days in advance, and it should be hung up to balance the temperature and humidity in the working environment, and eliminate or reduce the curl traces caused by packaging curling.
The upper part of the hollow steel pipe with a diameter greater than 100mm, the pipe length should be greater than the width of the sand belt. The lower part should be pressed into a hollow steel pipe with a diameter greater than 150mm, straightened up and down, and placed on the site for storage.
3, the characteristics of abrasive belt grinding
Abrasive belt grinding technology after decades of application and development, is moving towards strong, efficient, automated, precision and ultra-precision direction, the world's major countries abrasive belt grinding technology and grinding machine varieties are changing with each passing day, especially in the United States, Germany and Japan and other countries even more, the past can not be grinding parts, has been abrasive belt grinding machine to solve. In recent years, China's abrasive belt grinding technology has been greatly developed, its application is expanding, aerospace, steel, shipbuilding, mechanical processing, bamboo rattan processing, architectural decoration, leather products, glass, ceramics, wood furniture, stainless steel products processing, sports and health, Musical Instruments and other industries have introduced abrasive belt grinding processing technology. In addition to the general grinding of ordinary metal or non-metal workpieces, abrasive belt grinding is also used in the manufacturing and processing of precision parts such as disks, tape recorders, video recorders and copiers, and has developed one of the effective means of efficient, precision, and ultra-precision processing. The characteristics of abrasive belt grinding process are mainly as follows:
01, belt grinding is elastic grinding
The elasticity comes from the elastic deformation of the contact wheel during the grinding of the contact wheel and the abrasive belt itself, the grinding arc increases, and the abrasive particles are involved in the increase, thus improving the grinding efficiency, so that it is difficult to achieve the purpose of controlling the size through light grinding like the grinding wheel. Since the substrate and binder that make up the sand belt have certain elasticity, and most of the contact wheel is made of elastic rubber, the sand belt grinding has the same sliding, ploughing and cutting effects as the grinding wheel (extrusion, sliding effect is larger), and the grinding particles squeeze the workpiece surface. The synthetic effect of surface plastic deformation, hardening layer change, surface tearing and thermoplastic flow of workpiece. Therefore, belt grinding has multiple functions of grinding, grinding and polishing at the same time, so the surface quality is good. The elastic grinding will increase the contact length, and the entire abrasive belt wear is much smaller than the grinding wheel.
02, the abrasive belt grinding process has higher grinding efficiency and productivity
Because many manufacturers use electrostatic planting sand to evenly distribute each sand particle on the substrate, so that the sharp Angle processing surface of the sand grain faces up to the processing surface, thus greatly improving the grinding efficiency of the sand belt. Even if stainless steel and other high-hardness, high-toughness metal materials, such as blades, ground springs, valve bodies, locks and other stainless steel casting and forging, the processing margin can be greater than 3-5mm, especially for non-ferrous metal die-casting, to remove the hair, the efficiency of the work than the traditional grinding wheel and file hair increase 5-6 times, and the surface roughness is greatly reduced. For example, a weaving machinery foundry originally processed hair removal, to flash a process, with the traditional grinding wheel and file processing, with more than 20 people, must use sand belt grinding, although the production batch is expanding, only 3-5 people can be completed, its appearance quality has been greatly improved. For example, the workpiece plane or irregular surface of carbon steel material is processed, and the metal removal rate is some greater than 1.25cm3/cm2. For the various types of plate hands, scissors, pliers, precision stamping parts, chamfering, especially for the tool industry of hot calcined parts, large flash, shape processing allowance, large production batch, grinding and polishing with traditional grinding wheel, that is, unsafe, dust and civilized production situation is poor, and product quality is not high. Shanghai has a production of plate hand enterprises, all use sand belt grinding, work efficiency more than doubled, product quality is the first in the industry, civilized production has been greatly improved.
Abrasive belt strong grinding can be comparable to turning, milling and planing, the material cutting depth of 2.5-3mm, high metal cutting rate, the grinding time is shortened by 75% than the grinding wheel, the power utilization rate is 85-96%, almost most of the converted into useful work, the power consumption rate is 34% of the surface grinding wheel grinding, is a metal cutting machine tool with higher efficiency.
03, the processing surface quality is good
Abrasive belt grinding is elastic grinding, the cutting force is relatively small, the workpiece deformation is small, the stability of the processing system is good, the grinding rigidity is small slender shaft and thin disk parts, but also can achieve satisfactory results. Compared with the grinding wheel grinder, the circumference of the sand belt is long and the heat dissipation effect is good, so it is called cold grinding, so the processing metamorphic layer is thin and will not affect the heat treatment effect. In addition, the sand belt can be changed according to the particle size, to achieve different roughness on the same machine tool, up to the degree of mirror.
Because the abrasive belt grinding process is cold grinding, the surface of the workpiece is not easy to be burned, because the abrasive belt not only takes away the heat generated during processing during the grinding movement, but also evolves the generated trace vibration to improve the cutting effect, in order to achieve the purpose of low roughness. Generally speaking, as long as the process selection is reasonable, for the workpiece with the original roughness of Ra≤2.5μm, the effect of mirror grinding can be achieved by the sand belt processing of Ra≤0.01μm. If the user needs the coarse hair effect, or the embodiment of the uniform molecular structure of the metal surface, it can also achieve the best effect. For example, the hand sawing of 65mn material is to lay the molecular structure of the surface of the metal body on the surface to achieve a smooth and beautiful effect. For example, the piston rod, hydraulic rod, shock absorber rod, etc., after electroplating, the abrasive belt grinding can reduce its roughness, improve the wear resistance of the workpiece, and extend the service life of the workpiece.
04, belt grinding than the general car, pliers, planer, grinder adaptability, and can solve the grinding wheel grinding can not be solved
Such as large areas (wood, steel) and complex surface grinding (such as engine blades), if the use of consolidated grinding tools (grinding wheels, etc.) can not be ground, and the use of sand belt can be achieved. Because coated abrasives (sand belts, etc.) are a flexible grinding. For example, the 2M595 and 2MA595 universal sand belt beds produced by Xinxiang Machine Tool Factory can be used to grind and polish curved surfaces as well as to grind small surfaces. For example, the 2MJ5810 common surface abrasive belt grinder of Xinxiang Machine tool Factory can be operated in vertical or horizontal position according to different workpieces, and it is very convenient for grinding plane, grinding square, chamfering, grinding arc, deburring and polishing. Xinxiang Machine tool Factory also designs a abrasive belt grinding head, which can be installed on a horizontal or vertical lathe to grind the inner circle (hole), the outer circle and the end face, and can also be installed on a planer to grind the large plane.
05, the belt grinding cost is low auxiliary time
Because of the high production efficiency of the abrasive belt grinder, the user machining workpiece cost is low, and the auxiliary time to replace the abrasive belt only needs 3-5 minutes each time, the working process does not need dressing, and the replacement of the grinding wheel is more laborious, the grinding wheel balance also takes time, and the auxiliary time has to be constantly trimmed during the working process is much more than the abrasive belt grinding.
In addition, the abrasive belt grinder is easy to implement coarse, medium and fine grinding at one time to complete the grinding task, such as the sanding bed used for wood processing has a structure of double sand frame, four sand frame, six sand frame until eight sand frame, and the grinding process can be completed from the board to the end of one process, and the operation process is relatively simple. Unlike grinding wheel, if you want to complete the coarse, medium and fine grinding task on a grinding machine, at least the second grinding wheel can be completed, the changing grinding wheel, the smooth grinding wheel and the debugging assistance time of grinding wheel is very long, such as the grinding with sand belt will save much time, naturally it will save much time, and the cost is much lower than grinding wheel.
06, safe use, small dust, low noise, easy to control, good environmental conditions
If there is an accident, the grinding wheel will break, which will hurt people or damage the equipment in serious cases. However, even if the grinding belt breaks, it will not cause personal injury and equipment accidents, which is safer and the operator can master the operation skills quickly. In addition, the sand belt will not be as desanded as the grinding wheel, and it is easy to collect and dust when dust is generated, and the dust is very small; In addition, the noise of abrasive belt grinding is small, especially the use of rubber contact wheels, unlike the rigid impact of grinding wheels, so the noise is very small when used, generally below 60 decibels, from the Angle of environmental protection, abrasive belt grinding is also feasible.
07, the speed of abrasive belt grinding is stable
Grinding wheel continuous wear and use of the grinding wheel dressing, because the diameter of the grinding wheel becomes smaller and affect the grinding efficiency. The efficiency of grinding wheel is closely related to the speed of use (V=π*D*N), the smaller the speed, the lower the grinding efficiency, and the belt is always grinding at a constant speed, which is especially a prominent and valuable feature for grinding small surfaces and high-precision workpieces.
08, save abrasive
The abrasive utilization rate of the abrasive belt used in abrasive belt grinding is high, especially after the use of electrostatic sand planting process, the abrasive layer is in effect, and there is no problem like the abrasive wheel is often corrected and the wear particle is lost in use, so the abrasive utilization rate of abrasive belt grinding is extremely high, as high as 95%.
09, sand "cold" grinding is another prominent feature of sand belt grinding
The so-called "cold" grinding is compared with grinding wheels. The temperature of the grinding wheel grinding in the grinding area is as high as 8000C, and the workpiece is prone to burn and deformation, so it is mostly used in the state of coolant, and the use of dry grinding can only be used for some parts that will not affect the surface quality of the workpiece due to grinding heat. In the process of abrasive belt grinding, the workpiece temperature is low, and thermal deformation and burn phenomenon will not occur. Because the sand belt circumference is long, the grinding heat dissipation time is long, and the sand belt adopts electrostatic planting sand, the abrasive particles are evenly arranged, the tip is upward, and the chip space is large, so the cutting is sharp and the friction heat is small.
10. Abrasive belt grinding belongs to a kind of coated abrasive grinding
Abrasive belt grinding is a kind of coated abrasive grinding, and it is also a kind of efficient, economical and widely used grinding process, which is called "universal grinding". The application range of abrasive belt grinding is extremely wide, almost can process all engineering materials, and even People's Daily necessities, can complete a series of work from rough grinding, semi-fine grinding, fine grinding to grinding, polishing and so on. The ability of abrasive belt grinding from strong and efficient to high precision processing is omnipowerful, which is increasingly valued by people, and the characteristics of abrasive belt grinding are more and more accepted by people, which is an important feature of the development of abrasive belt into a more complete, mature and self-contained system and the development of consolidated abrasive tools and superhard abrasive tools.
Abrasive belt grinding also has places that are not competent, such as small holes less than Φ25mm, blind holes with dimensional accuracy requirements, cavities, etc., are also difficult to use abrasive belt grinding to process; For multi-step circular receding grooves less than 3 mm, it is not possible to use sand belt grinding. In addition, at present, it is not possible to use this method for thin plate parts with thickness less than 0.2 mm, tooth grooves, worm wheels, and worm. At the same time, it is difficult to use sand belt grinding for parts with high precision and high surface roughness. All these need to be solved by further research and development of belt grinding.
