What is an electric polishing machine


Electric polishing machine is an electric tool. The polishing machine is composed of basic components such as base, throwing plate, polishing fabric, polishing cover and cover. The motor is fixed on the base, and the cone sleeve for fixing the polishing disc is connected with the motor shaft through screws. After turning on the power switch of the polishing machine, the pressure can be applied to the polishing ring on the base of the polishing machine by hand. The polishing liquid added in the polishing process can flow into the square plate next to the polishing machine through the drainage pipe of the plastic plate fixed on the base. The polishing cover and cover can prevent dust and other sundries from falling on the polishing fabric when the machine is not in use and affecting the use effect.

 

Definition of electric polishing machine

 

As the name suggests, the electric polishing machine takes electricity as its power source. Because it has a motor inside, the electric polishing machine is much heavier than the pneumatic polishing machine, which is about 3kg, which is not conducive to the long-term work of maintenance workers. However, compared with the pneumatic polishing machine, the speed of the polishing machine will be constant when rotating, and there will be no low air pressure and slow speed, but it is generally divided into no-load and loaded states, Some polishing machines have normal speed under no-load condition. As long as they are loaded, the speed will drop immediately. In terms of safety, the electric polishing machine has no pneumatic safety. The rotating speed of the electric polishing machine generally has five gears. A lower rotating speed is used when beating liquid wax and a higher rotating speed is used when removing dried wax.

 

Classification of electric polishing machines

 

Single action polishing machine and double action polishing machine

 

The single action polishing machine is what we call the same center machine. The center of the polishing disc is consistent with the center of the rotating circle. The maximum speed of this kind of polishing machine is generally about 4000R / min. Double acting polishing machine is what we call eccentric machine, that is, the center of the polishing disc is inconsistent with the center of the rotating circle. We call the distance from the center of the circle to the center of the circle as eccentric distance. Its maximum speed is generally related to eccentricity. The larger the eccentricity, the lower the maximum speed, the smaller the eccentricity, and the higher the maximum speed. When the eccentricity is 0, the speed is low. This parameter is related to the cutting force of the polishing machine on the paint surface. At the same speed, the cutting force of the same center machine on the paint surface is much larger than that of the eccentric machine, and the cutting force of the polishing machine with large eccentricity is much larger than that of the polishing machine with small eccentricity.

 

Comparison between single action polishing machine and double action polishing machine

 

(1) Trajectory comparison

 

The single action polishing machine runs in concentric and single direction, and the running track is also very single. The rotation radius from the center of the circle to the edge increases in turn, and its cutting force will increase with the increase of the radius, that is to say, the edge cutting force of the polishing disc is the largest, and it is very easy to produce circle marks after polishing, which is what we call solar stria. It is precisely because of its large cutting force that the efficiency of grinding and polishing will be improved. The disadvantage is that it will grind the paint on the surface very thin and accelerate the aging of the paint.

 

The model of electric eccentric machine is divided into 12mm, 15mm and 21mm, and the speed decreases in turn. Generally, the maximum speed of 12mm polishing machine can reach 5500r / min, and that of 21mm polishing machine can reach 4200r / min.

 

(2) Comparison of heat changes

 

When polishing with a single action polishing machine, we usually add water to the abrasive or spray a layer of water droplets on the abrasive after brushing the abrasive on the paint, so as to reduce the heat of the paint and polishing disc during polishing. However, in this case, the symptoms are generally treated rather than the root cause. When the water is consumed by the polishing disc, the polishing disc and paint surface will still be very hot. As the polishing disc is only a simple rotary motion, many maintenance workers will exert great pressure on the polishing disc in pursuit of work efficiency

 

Some maintenance workers like to throw a position for a long time when polishing, which is not conducive to heat dissipation. Finally, the paint surface is damaged and the polishing disc is damaged. The polishing efficiency of double action polishing machine is lower than that of single action polishing machine. Because it shakes during polishing, its heat dissipation effect is much better than that of single action polishing machine. The double action polishing machine does not need to spray water on the paint surface during polishing. It can be polished directly after applying polishing agent. Note that the polishing agent must be applied on the polishing disc. In addition, during polishing, it is necessary to ensure that the polishing agent on the paint surface is wet and avoid dry polishing, because the grinding particles of the dried polishing agent are very easy to scratch the paint surface. Therefore, it is generally not allowed to collect the polishing agent very clean. After polishing, it is best to show the trace of cloud like polishing agent on the paint surface, and it is best to check the polishing effect of the whole paint surface through this trace (no scratch, no circle mark, etc.).

 

usage method

 

The key to the operation of electric polishing machine is to try to get the maximum polishing rate, so as to remove the damaged layer during polishing as soon as possible. At the same time, the polishing damage layer should not affect the final observed tissue, that is, it will not cause false tissue. The former requires the use of coarse abrasive to ensure a large polishing rate to remove the polished damage layer, but the polishing damage layer is also deep; The latter requires the use of the finest material to make the polishing damage layer shallow, but the polishing rate is low.

 

The best way to solve this contradiction is to divide polishing into two stages. The purpose of rough polishing is to remove the polishing damage layer. This stage should have the maximum polishing rate. The surface damage formed by rough polishing is a secondary consideration, but it should also be as small as possible; The second is fine polishing (or final polishing), which aims to remove the surface damage caused by rough polishing and minimize the polishing damage. When polishing with the electric polishing machine, the grinding surface of the sample and the polishing disc shall be absolutely parallel and evenly pressed on the polishing disc, and attention shall be paid to prevent the sample from flying out and generating new grinding marks due to too much pressure. At the same time, make the sample rotate and move back and forth along the radius of the rotary table to avoid local wear of the polished fabric too fast. In the polishing process, continuously add micro powder suspension to keep the polished fabric at a certain humidity. Too much humidity will weaken the effect of polishing wear marks, make the hard phase in the sample appear convex, and the "tail dragging" phenomenon of non-metallic inclusions in steel and graphite phase in cast iron; When the humidity is too small, the friction heat will raise the temperature of the sample, reduce the lubrication, lose the luster of the grinding surface, and even appear black spots, and the light alloy will damage the surface. In order to achieve the purpose of rough polishing, the rotating speed of the rotary table is required to be low, preferably not more than 600r / min; The polishing time should be longer than the time required to remove the scratch, because the deformation layer should also be removed. After rough polishing, the grinding surface is smooth but dull. Uniform and fine grinding marks are observed under the microscope and need to be eliminated by fine polishing.

 

During fine polishing, the speed of rotary table can be appropriately increased, and the polishing time is appropriate to throw away the damaged layer of rough polishing. After fine polishing, the grinding surface is as bright as a mirror, and no scratches can be seen under the bright field of vision of the microscope, but the grinding marks can still be seen under the condition of phase contrast lighting. The polishing quality of electric polishing machine seriously affects the microstructure of the sample, which has gradually attracted the attention of relevant experts. A lot of research work has been done on the performance of polishing machines at home and abroad, and many new models and new generation of polishing equipment have been developed. They are developing from the original manual operation to a variety of semi-automatic and full-automatic polishing machines.

 

That's all for today's knowledge sharing. Do you have any ideas? Welcome to leave a message in the comments. See you next time.