Knowledge of the relationship between the grinding area of a centerless grinder and the workpiece standard
1: Because centerless grinding relies on the dressing angle of the guide wheel and the inclination angle (grinding angle) of the guide wheel, a spiral line occurs between the grinding wheel and the guide wheel, and then the workpiece is pushed forward. In this case, because the guide wheel is trimmed to a double curved surface by adjusting the trimming angle, the orientation of the grinding wheel and the blade is horizontal and fixed. Assuming that adjusting the inclination angle of the curved surface can change the contact area with the guide wheel and the grinding wheel, this contact surface is the grinding area. The length of the grinding area will affect the utilization power of the grinding wheel, the processing smoothness, roundness, cylindricity, and the length of grinding time.
2: The grinding area theoretically needs to reach about 80% of the width of the grinding wheel. Workpieces with different lengths may have slight differences. Generally, if a good workpiece standard is obtained by the general method of centerless grinding, the length of the workpiece is generally about 1.5 times the width of the grinding wheel. Of course, this data is not fixed, it is only an approximate value, and it is not entirely applicable to all artifacts.
3: If the grinding amount is different, the inclination angle of the unstrained guide wheel will increase due to the increased grinding amount, and the grinding area of the workpiece will also be offset forward. As mentioned above, the theoretical grinding area is about 80 times the width of the grinding wheel. Assuming that we grind a workpiece with a diameter of 10 mm and a length of 150 mm, assuming that the grinding amount is 0.02, the trimming angle of the guide wheel is 2.0 °, and the inclination angle of the guide wheel is 2.3 °, the grinding area is about 80 degrees normal. The workpiece standard for this type of processing is normal. Assuming that we do not change the above parameters, only increase the grinding amount and grind each time by 0.05 mm, then after adjusting the grinding orientation, We will find that 90% or 100% of the grinding area has been ground by the grinding wheel. In this way, the workpiece may appear small and large at both ends, and may have poor roundness and finish. If we want to improve, we just need to remember the theoretical grinding area, and then adjust the inclination angle of the guide wheel to 2.5 °, so that the grinding orientation and area of the workpiece are always about 80%. In this way, the grinding amount can be adjusted within a certain range, and better accuracy can be obtained by adjusting the inclination angle of the guide wheel.
4: Assuming that the grinding area is less than 80, when machining short and long workpieces, it has little impact on the standard, but it will affect the processing power. Because the grinding area is too short, the orientation of grinding wheel wear is concentrated in a single point, and when the grinding wheel is excessively worn, the grinding angle will change and cause adverse effects.
Assuming that the sand particles from the grinding area to the surface of the 80 grinding wheel can uniformly cut the workpiece without severe partial wear, this will add processing power and reduce the number of dressing times of the grinding wheel.
After adjusting the guide wheel inclination angle and the small touch area of the workpiece, the included angle of the workpiece will also tilt with the guide wheel plane. After tilting, the head and tail of the workpiece will be ground off during grinding, which forms the symptom of small ends at both ends. On the contrary, because the workpiece can be ground at both ends, if it is not ground properly or not sufficiently, it will result in a small workpiece and a large workpiece at both ends.
6: In general, the cooperation between the dressing angle of the grinding wheel and the guide wheel and the inclination angle of the guide wheel is related to the accuracy of the workpiece. Those who do centerless grinding must know the adjustment method for the dressing angle and grinding angle of the guide wheel, otherwise it is difficult to adjust the centerless grinding.
Centerless grinding machines are a type of grinding machines that do not require the use of the axis of the workpiece for grinding. "It is composed of three mechanisms: a grinding wheel, an adjustment wheel, and a workpiece holder. The grinding wheel actually performs the grinding task. The adjustment wheel controls the rotation of the workpiece and causes the workpiece to have a feed speed. As for the workpiece holder, which supports the workpiece during grinding, there can be several ways to cooperate with these three mechanisms, except for stopping grinding, which is the same in principle.". Centerless grinding machines can automatically trim and compensate. The guide wheel feed guide rail is a dual V-shaped needle roller guide wheel fed by a servo motor that can compensate for grinding wheel dressing. The machine tool is equipped with an automatic loading and unloading mechanism, which can perform automatic circular grinding. The development of centerless grinding machines has gone through the process of completely relying on system suppliers to initially having general development capabilities. However, the application of CNC systems is still in the stage of improving the performance of mechanical transmission chains, replacing mechanical handwheels, and simple processing cycles. Compared with advanced levels, centerless grinding machines still have many gaps, and there is a lot to improve in terms of machine tool accuracy, automation functions, processing efficiency, and reliability of centerless grinding machines Breakthrough issues need to be resolved. Summarize the various structures and use processes of various products currently produced, analyze their advantages and disadvantages, explore what automatic functions the product should achieve, and have a plan for its gradual development to facilitate learning and work; Attaching importance to the development of CNC software, centerless grinders have the conditions to introduce technology or learn from overseas, to keep up with the development trend. In terms of hardware, combined with market needs, centerless grinders will apply new technologies and new functions one by one in product manufacturing, in order to narrow the gap with advanced levels. In the centerless grinding machine industry, to promote industrial progress. The formulation of new standards and the revision of old standards lag far behind the development of the industry. Due to changes in government agencies, industry standards have not been addressed. Given the very backward standards, it seems impractical for mindless grinders to propose creating international brands. To create an international brand of centerless grinding machines, domestic standardization work must take the lead. To further establish contacts with international standardization organizations and establish cooperative relationships based on communication, thereby improving the international competitiveness of China's product standards, creating an international brand has the foundation.
The general operating method is to come back three laps during the feed and then enter three laps to remove errors caused by gaps. If it is still inaccurate, we need to perform other operations. Have a brief understanding of how to handle this matter. 1. Check to see if the screw brake handwheel is locked. If you are not sure about it, the two pins of the brake handwheel tap against the screw rod have fallen off. Grasp the screw brake handwheel tap and check for reinstallation. If the feed of the lower slider is not accurate, check whether the left or right side of the object rack has touched the falling workpiece. This problem sometimes occurs and needs to be checked. 2. For centerless grinding machine types, because the tool is fed from the lower right corner, check whether the set screw of the feed handwheel and the anti retraction screw on the feed screw are loose or the gap is too large. Rolling back and forth feels like the gap between the handwheels is too large, or if the handwheel is too tight when rotating. 3. Slightly adjusting the offset or looseness of the feed housing downward will cause the sliding conflict to cause excessive clearance between the helical gear and the adjustment screw. Or tightening the nut will make the rotation inflexible. Generally, loose nuts can also lead to inaccurate feed. 4. Both the handwheel fine adjustment and the screw rod differential disc drive screws have fixed screws, and it is also necessary to ensure that there are no looseness, fine adjustment screws, and the edge bearing of the screws to ensure that there is no wear or excessive clearance. For slightly worn parts, they can be properly tightened, and severely worn parts need to be replaced in a timely manner. Matching high-quality parts as much as possible can improve the feed accuracy of the grinding machine and reduce the maintenance rate of the machine.
A grinding machine that uses a centerless grinding method to grind the rotating surface of a workpiece is commonly referred to as a centerless cylindrical grinding machine. On a centerless cylindrical grinding machine, the workpiece is not centered and supported by the center, but is placed between the grinding wheel and the guide wheel and supported by the tray and guide wheel. The grinding wheel is generally installed at the end of the spindle, and the grinding wheel with a width greater than 250mm is installed in the middle of the spindle. The width of the grinding wheel can reach 900mm. The grinding wheel rotates at a high speed for grinding, and the guide wheel rotates at a slower speed in the same direction, thereby driving the workpiece to rotate for circular feed. During grinding, axial feed is achieved by adjusting the slight inclination of the guide wheel shaft, which is suitable for grinding elongated cylindrical workpiece, short shaft without central hole, and sleeve type workpiece. In the process of plunge grinding, radial feed is achieved through the movement of a guide wheel frame or grinding wheel frame. It is suitable for grinding workpieces with shoulders or bosses, as well as cones, spheres, or other workpieces with curved curves. Centerless grinding machines have high productivity and are easy to automate with the addition of various handling devices. Most of them are used for mass production and can be operated by unskilled workers. The grinding accuracy of centerless grinding machines is generally 2 microns for roundness and 4 microns for dimensional accuracy. High precision centerless grinding machines can reach 0.5 microns and 2 microns respectively. In addition, there are centerless internal grinding machines and centerless thread grinding machines. Centerless grinder can automatically trim and compensate. The guide wheel feed guide rail is a dual V-shaped needle roller guide wheel supplied by a servo motor and can be mutually compensated by grinding wheel trimming. The machine tool is equipped with an automatic loading and unloading mechanism for automatic circular grinding.