The polishing process of stainless steel pipes can be divided into two parts: grinding and polishing. The two parts of the process and method are summarized as follows. Today, Hangao (SEKO) will show you the specific operation steps and precautions.
1. Grinding
Detailed instructions are as follows:
1. Visually inspect the workpiece that has been transferred to the polishing process in the previous process, such as whether there is leakage welding, welding penetration, uneven depth of welding points, too far away from the joint, local depression, uneven docking, deep scratches, bruises, severe deformation and other defects that cannot be remedied in this process. If there are the above defects, return to the previous process for repair. If there are no above defects, enter this polishing process.
2. Rough grinding, use a 600# sanding belt to grind the workpiece back and forth on three sides. The goal of this process is to remove the welding points left by the workpiece welding, as well as the bruises that occurred in the previous process, to achieve the initial formation of the weld fillet, and basically no large scratches and bruises on the horizontal and vertical surfaces. After this step, the surface roughness of the workpiece should reach R0.8mm. Pay attention to the inclination angle of the sanding machine and control the pressure of the sanding machine on the workpiece during the polishing process. Generally speaking, it is more appropriate to be in a straight line with the polished surface!
3. Semi-finishing grinding, use 800# sanding belt to grind the three sides of the workpiece according to the previous method of grinding the workpiece back and forth. It is mainly to correct the joints that appeared in the previous process and further fine-grind the marks produced after rough grinding. The marks left by the previous process should be repeatedly ground to achieve no scratches on the surface of the workpiece and basically brighten. The surface roughness of this process should be able to reach R0.4mm. (Note that this process should not produce new scratches and bruises, because such defects cannot be repaired in the subsequent processes.)
4. Fine grinding, use 1000# sanding belt mainly to correct the fine lines that appeared in the previous process, and the grinding method is the same as above. The goal of this process is to basically eliminate the joint between the grinding part and the unground part of the workpiece, and make the surface of the workpiece brighter. The workpiece after grinding through this process should be close to the mirror effect, and the surface roughness of the workpiece should reach R0.1mm
5. Instructions on changing the sanding belt: Generally speaking, a 600# sanding belt can polish 6-8 workpieces of 1500mm length, an 800# sanding belt can polish 4-6 workpieces, and a 1000# sanding belt can polish 1-2 workpieces. The specific situation depends on the welding spot of the workpiece, the pressure used for polishing, and the method of polishing. In addition, it should be noted that when changing the sanding belt, it must be ensured that the sanding belt can rotate smoothly on the sponge wheel to achieve the purpose of uniform grinding of the workpiece.
2. Lighting part
The main purpose of the light-emitting part is to mirror the stainless steel polished in the front to achieve the purpose of mirroring.
This process can be summarized as follows:
Two processes: waxing and polishing
Two motors, two wool wheels, blue wax, cloth
The specific contents are as follows:
1. Visually inspect the welded parts that enter this process from the previous process to confirm whether there are any problems that cannot be repaired in the light-emitting stage, such as missing grinding to 1000#, incomplete grinding of all welds, traces of rough grinding, serious damage to the protective film, excessive grinding, excessive rounding, serious grinding at both ends, uneven grinding, and different depths in some places. If there are such problems, they need to be returned for re-grinding or repair. (This process cannot repair the bruises, bumps, and large scratches that occur during grinding, but it can repair very fine lines, such as the relatively small fine lines polished by 1000#. But it is very troublesome)
2. Mirror surface
Use a wool wheel (available on the market) driven by a high-speed motor, and use Daqing wax to imitate the previous polishing method to mirror polish the workpiece after the previous polishing processes, rather than further grinding. Note that during this step, do not rub the polishing wax onto the covering film on the surface of the workpiece, and be careful not to damage the covering film.
3. Polishing
This process is the last process of mirror polishing. Use a clean cotton cloth wheel to rub the surface of the workpiece after the mirror, and clean and polish the workpiece after all the previous processes. The goal of this process is to make the workpiece surface indistinguishable from welding marks, and to polish the waxed and polished workpiece, with a brightness reaching a mirror reflection of 8k, and there is almost no difference between the polished and unpolished parts of the workpiece. Achieve a complete mirror effect.
4. Instructions on waxing:
a. Waxing method: Generally, the wool wheel is waxed before polishing the workpiece, and polishing is started after the wool wheel is full of blue wax. The waxing method is shown in the figure below:
b. Why can the high-speed motor directly drive the wool wheel to wax and polish the stainless steel workpiece to make it brighter: Because blue wax is an oily substance, it is solid at room temperature and liquid at high temperature. The high-speed motor directly drives the wool wheel to rotate at high speed. When the wool wheel surface is attached with blue wax, it is ground on the workpiece surface. Due to the oiliness of the oily substance, the surface of the workpiece becomes brighter. Therefore, the choice of the motor that drives the wool wheel for polishing is very important. According to actual experience, the speed of the motor used for polishing should not be less than 13000r/min, and its power should not be less than 500w. When the speed is lower than this speed, the brightness or mirror effect of the polished workpiece is not very ideal. Therefore, it is difficult for ordinary motors to meet its requirements. Generally, high-speed motors are selected.
c. The wool wheels on the market are divided into coarse wheels and fine wheels. The choice of wool wheel is very important. After polishing with a wool wheel with very rough wool, it is easy to have traces of polishing. In actual production, fine wool wheels are generally used, so that the polishing effect is good!
d. During the polishing process, the pressure on the workpiece must be controlled. Excessive pressure will cause the wool wheel to polish off too large an area of the protective film, and even blacken the workpiece, destroying the original mirror effect of the workpiece. Hangao OD polishing machines have auto compesation system. It could lift the polishing wheels up and down automaticlly by electric signal, to avoid the situation desribed above.
e. During the polishing process, the large blue wax must be continuously supplied, otherwise the wool wheel will smoke due to excessive temperature, which will cause serious wear on the wool wheel and damage to stainless steel.
f. For fine lines that need to be repaired in the light-emitting stage, they need to be repaired manually separately. The repair work is very troublesome. If possible, try not to perform any repair work at this stage.
g. The waxing motor is generally equipped with two motors, each motor is responsible for polishing one side of the workpiece. Depending on the situation, you can consider adding a motor for polishing the edges to increase the brightness of the edges.
h. Replace the wool wheel as needed.
A few additional points about polishing:
The polishing method is basically the same as the waxing method, except that the wool in waxing is replaced by the cloth wheel in polishing.
Polishing is the last process in the entire polishing process. It is necessary to ensure that there will be no damage to the mirror surface after the workpiece is polished, otherwise all the previous efforts will be wasted.
a. The polishing method is to install the cloth wheel directly on the high-speed motor to achieve high-speed rotation, wipe it on the surface of the workpiece, wipe off the dirt and attached blue wax on the workpiece, and achieve the purpose of polishing! In actual polishing, it is often accompanied by abrasive powder. Abrasive powder can remove the oily blue wax. Its main function in polishing is to easily remove the blue wax adhering to the workpiece. If it is not combined with abrasive powder, the blue wax on the surface of the workpiece will be difficult to remove, and it is easy to stick to other places, affecting the beauty of other places.
b. In order to obtain a workpiece whose brightness meets the mirror requirements, the clean condition of the cloth wheel is particularly important. In actual production, the cloth wheel needs to be replaced in time according to the specific situation.
