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Tungsten steel is also known as hard alloy, because its hardness is high ah, polishing difficulty is larger, generally speaking , the finer the particles, the lower the polishing difficulty, the coarser the particles, polishing difficulty is greater. And polish to mirror to face, difficulty can be more big. Only grasp the polishing method, can be more able to play tungsten steeled excellent characteristics.
Now many factories generally use grinding wheel polishing and polishing paste polishing two modes.
1 . Regular circular polishing method
Regular round tungsten steel polished to the mirror surface can be used 2000 grain diamond grinding wheel directly in the centerless grinding machine grinding and polishing.
2 . Regular square polishing method. Regular squares , most of which are machined in a surface grinder, can be polished with a 2, 000-grain diamond wheel.
3 . Method of polishing the inner hole of special-shaped tungsten steel.
Most manufacturers in tungsten steel polishing, mainly special-shaped products. So it is difficult to polish. For example, the inner hole is irregular shape, but the inner hole filled with cloth, the workpiece fixed, with two people on the pull , until the product hot, smoothness for the mirror.
4 . A polishing method of special-shaped tungsten steel. Tungsten steel shape irregular polishing, ultrasonic polishing, plus 4000 particle size polishing paste, grinding machine can be achieved mirror finish.
Because rolling processing is the processing method of roller rolling, the roughness of the surface after processing is affected by the height and shape of the convex part (that is, the state before processing).
If the surface state before processing is rough (the convex part is high, and the concave part is deep), the convex part cannot be completely embedded into the concave part, resulting in rough surface processing.
In addition, the shape of the raised part also affects the processed surface. Generally, the better the surface condition before processing, the better the surface condition after processing, and the less abrasion of rolling head. If necessary, an additional procedure can be added.
Since rolling processing is the processing method of roller rolling, the diameter of the workpiece before and after processing will change (the inner diameter will expand, the outer diameter will decrease). In order to be able to process into the dimensional tolerance range, this change should be taken into account to determine the size of the previous process. The change in diameter is related to the material, hardness and rolling capacity of the workpiece. Therefore, the size of the workpiece shall be determined after 2-3 trial machining.
The standard model of rolling head has straight shank and morse taper shank. Rolling and cutting machining is different, do not require large torque, small power machine tools can also be used. It can be installed in drilling machine, lathe, hexagonal lathe, boring machine, drilling machine and other equipment for processing, and do not need special equipment.
Because rolling processing is the use of roller rolling processing, so it will produce fine dust. Dust not only affects the surface quality, but also accelerates the loss of rolling head, so it is necessary to inject a large amount of cutting fluid to remove dust. Low viscosity cutting fluid should be used in rolling processing. High viscosity cutting fluid although lubricity is good, but its cleaning performance is poor, not suitable for rolling processing. The company has rolling processing special rolling lubricating oil, as long as the low viscosity cutting fluid mixed with 5% rolling lubricating oil, can play its outstanding performance.
Rolling processing is the use of roller rolling processing part of the surface to make it compact. Therefore, in order to be able to withstand the pressure of processing, the waiting part should have a full wall thickness (20% of the inner diameter). If the wall thickness is too thin or part of it is thin, it will fluctuate or decrease the roundness after processing.
Usually according to the following methods to solve the problem: (1) reduce the rolling amount; (2) use fixtures to support the periphery; (3) roll machining is carried out before cutting thin wall thickness.
The upper limit of hardness of workpiece machinable by rolling head is 40HRC, but we also specially manufacture rolling head for high hardness workpiece (the upper limit of hardness is 55HRC). When rolling the workpiece with high hardness, the tool life will be shortened due to the large pressure that the processed part bears. Therefore, in order to obtain the machining surface with required precision, the main measure is to reduce the rolling amount.
Rotate the rolling head to the right for rolling processing; The rolling head can also be fixed and the workpiece can be rotated to get the same result. The rotational speed and feeding speed are different according to the machining diameter.
Polishing refers to the processing method that makes the surface roughness of the workpiece reduced by mechanical, chemical or electrochemical actions to obtain a bright and smooth surface. It is the use of polishing tools and abrasive particles or other polishing media on the surface of the workpiece modified processing.
Mechanical polishing is a method of polishing a smooth surface by cutting or plastic deformation of the material surface to remove the convex part after being polished. Mechanical polishing generally USES the whetstone bar, wool wheel, sandpaper, and so on, mainly manual operation. Special parts, such as the surface of the rotary body, can be used by the turntable and other auxiliary tools. The workpiece with high surface quality may adopt the method of super fine grinding and polishing. Ultra-fine grinding and polishing is a special grinding tool. In the grinding and polishing liquid containing abrasive materials, it is pressed on the surface of the workpiece being processed for high-speed rotational motion. Surface roughness of Ra0.008μm can be achieved by using this technology. This method is the highest of all polishing methods. This method is often used in optical lens mould.
Chemical polishing is to make the surface of the material in the chemical medium surface protruding part than the concave part of the first dissolution, so that smooth surface. The main advantage of this method is that it does not require complex equipment and can polish the workpieces with complex shapes, and many workpieces can be polished at the same time. It works efficiently. The key problem of chemical polishing is the preparation of polishing liquid. The surface roughness obtained by chemical polishing is generally 10μm.
The basic principle of electrolytic polishing is the same as chemical polishing, that is, the surface of the selectively dissolved material is slightly protruding to make the surface smooth. Compared with chemical polishing, the effect of cathode reaction can be eliminated and the effect is better.
The electrochemical polishing process is divided into two steps:
(1) macro leveling
The solution diffuses into the electrolyte, the surface of the material decreases geometrically, Ra>1μm.
(2) slightly smooth
Anode polarization, increased surface brightness, Ra<1μm.
The workpiece is put into the abrasive suspension and put together in the ultrasonic field, and the abrasive is ground and polished on the surface of the workpiece by the ultrasonic oscillation. The macroscopic force of ultrasonic machining is small, which will not cause deformation of workpiece. Ultrasonic machining can be combined with chemical or electrochemical methods. On the basis of solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution to separate the dissolved product on the surface of the workpiece, and the corrosion or electrolyte near the surface is even.
Fluid polishing depends on the high-speed flow of the liquid and its carrying abrasive particles to flush the surface of the workpiece to achieve the purpose of polishing. Common methods are: abrasive jet machining, liquid jet machining, fluid power grinding, etc.
Magnetic grinding and polishing is to use magnetic abrasive under the action of magnetic field to form abrasive brush, grinding the workpiece. This method has high efficiency, good quality and easy control of processing conditions. With suitable abrasive, the surface roughness can reach Ra0.1μm.
