Accuracy is one of the main assessment indicators of Spiral Bevel Gears. In order to ensure the accuracy of the gears, the conventional process measures are: use high-precision milling machine; equipped with high-precision fixtures; control heat treatment deformation to reduce the impact of heat treatment deformation on the accuracy of the gear. 1 machine tool accuracy After repeated exploration, it was found that the most important factor affecting the accuracy of the machine tool is not the wear and tear of the transmission chain (which is one of the influencing factors, of course, but the cost of repair is extremely high), but the problem of the wear of the rocker bearing of the machine tool. When the Y2250 machine rocker bearing wears seriously, it will cause the axial turbulence and vibration of the cradle, which will cause the radial runout of the gear ring to be large and cause the surface roughness of the tooth surface to be large. There are two main reasons for the Y2250 machine tool bearing wear, the first is the design of the lubrication system of the machine tool, the lubrication oil is too small, and the oil is not good for inspection (especially the rear bearing); the second is the resistance of the domestic casting. Grinding is not good. 2 cutting process The tooth cutting process includes tooling design and manufacturing accuracy, operating cutting sequence, operating specifications and finishing allowances. 2.1 Design and Manufacturing Accuracy of Gear Cutting Tooling 2.2 Cutting sequence in operation <br> After performing a large number of ring gear radial runout tests on the BJ130 large wheel, the radial runout of the ring gear is cyclically changed, and the cycle length corresponds to that of the gear. One lap, that is, the cycle is 2π radians. Therefore, according to this principle, the fine concave and convex surfaces of the small wheel are separately machined with two machine tools, which plays a very good role in stabilizing and improving the accuracy of the small wheel's cutting teeth. The specific approach is: Fig. (2) When processing the second surface (the convex surface of the small wheel, and the work piece is about 0.02 mm), a different tooth is used as the first tooth when processing the second surface. After testing with 10 products in each case, it is found that When the concave and convex surfaces of the small wheel are machined by two Y2250 machines, respectively, when the same tooth is used as the first machining tooth of the concave and convex surfaces respectively, the accuracy of the cutting teeth of the small wheel is the best. After more than 3 months of testing, the method randomly checks the data of 30 ferries on a daily basis and finds that the ring gear of the small wheel is 0.02 mm to 0.05 mm after the tooth cutting and is very stable. After this kind of precision wheel has been heat-treated, it can ensure that about 95% of the product bouncing is less than or equal to 0.07 mm, and about 5% is about 0.08 mm to 0.10 mm. 2.3 Operational Specification and Refined Margin <br> For large wheels, products that have been found to have large jitters after inspection have often had debris on the large wheel alignment surface, or small bumps on the large wheel alignment surface. Therefore, we have made the following regulations on operation and processing: 3 Heat Treatment Deformation Control and Correction In the heat treatment deformation, the deformation of the big wheel is more serious. The qualified rate of BJ130 large round heat treatment deformation is only 40%, and 60% need to be flattened by hydraulic press. We have accumulated the following experience in the correction of big rounds. 4 Accuracy detection and accuracy classification before pairing For the conventional manufacturing process of spiral bevel gears, accuracy testing is generally not performed before pairing. However, the T20 pairing machine produced by Oerlikon can display the accuracy of each paired product to determine whether the matching accuracy of the product is acceptable. ΔFrΣ=ΔFrA+ΔFrB (1) In the formula, ΔFrΣ—the sum of the radial runouts of the large and small ring gears, mm Table size wheel radial runout classification mm To meet the requirement of ΔFrΣ = 0.175 mm ≈ 0.18 mm, we use the following combination of methods for the BJ130 spiral bevel gear: 5 Conclusion After long-term practical verification, the following measures can be taken to improve the manufacturing accuracy of the spiral bevel gear. TDS water quality detection pen is a detection device used to analyze the total salinity of water quality. TDS in Chinese means total dissolved solids, which is defined as the total amount of various soluble mineral salts in water, including the total amount of inorganic salts and organic substances. TDS Meter,TDS Ph Tester,Water Quality TDS Tester,TDS Ph Tester Meter Filterelated Corp. , https://www.filterelated.com
Nowadays, many agricultural vehicles use BJ130 parts. The accuracy requirements of the spiral bevel gear drawings are as follows: Larger-sized spiral bevel gears (hereinafter referred to as large wheels) have a radial runout of 0.11 mm and smaller size arc teeth. The bevel gear (hereinafter referred to as the small wheel) has a radial runout of 0.065 mm. We use the Y2250 machine tool to process these two kinds of gears. According to our actual processing conditions, we have taken some measures in the following aspects to improve the gear accuracy for your reference.
For the Y2250 machine tool, the bearing of the rocker is easy to repair and the cost is relatively low. The method is to use the vertical lathe of the cradle and the inner hole of the bearing seat to polish and measure the actual size d1 and inside of the outer circle. The actual size of the hole D1, and then equipped with a bearing roller, the outer diameter of the roller d0 = (D1-d1) / 2 + 0-0.01-0.02 mm, and to ensure the uniformity of the size of the roller is better. After the Y2250 machine tool was repaired by this method, the gear ring runout of the big wheel was improved from 0.09 mm to 0.17 mm to 0.04 mm to 0.08 mm (the data was measured when the tool was 0.03 mm in radial direction and 0.02 mm in axial direction. ).
After the machine tool is repaired, the machine tool should be adjusted and checked as follows: (1) Adjust the gap of the cutter head spindle so that the spindle can run around 0.01 mm. 2 Adjust the workpiece spindle clearance so that the radial and axial runout of the spindle is between 0.006 mm and 0.01 mm. 3 Adjust the worm gear and worm gear to a range of 0.02 mm to 0.05 mm. 4 adjust the workpiece spindle worm gear, worm gap between 0.01 mm ~ 0.03 mm. 5 Check and adjust the gear and key coordination on each drive shaft. 6 Check other parts for serious wear or damage.
2.1.1 Big wheel tooling For manufacturers who do not have conditions to manufacture spring disc fixtures, two types of big wheel tooling can be used. If it is a large batch of products is best to use the overall fixture, this can ensure that the quality of a good fixture jump: 0.01 mm in the radial direction, 0.005 mm in the axial direction, also installed on the machine, the radial runout is about 0.015 mm, axial The jump is about 0.008mm. For multi-type, low-volume products, separate fixtures should be used, because it is easy to reduce the cost of the tooling, this structure of the tool on the milling machine measured radial runout of about 0.03 mm, axial 0.02 mm ~ 0.03 mm.
2.1.2 After the wheeled tooling had been repeatedly studied on the original design of the wheeled tooling, it was found that one place could be improved. That is, the top screw hole of the front cone of the wheeling tool was changed from 2-M12 to evenly distributed. —M12, this screw hole can be used to fine-tune the tooling runout with the M12 ejector screw when the alignment tool is beating. In general, the use of padding in the tooling of the small wheel can only find the positive jump of 0.015 mm to 0.03 mm, while using the ejector screw can find the positive jump of 0.005 mm to 0.01 mm. The jump value is used to calibrate the stick in the tooth. The position measured in the middle of the face is faster than the method using the pad, and the accuracy is high. At the same time, the large-wheel and small-wheel tooling (including elastic sleeves) adopts 20CrMnTi material for carburizing and quenching to improve the service life of the tooling.
(1) First locate the first tooth on the first side of the machine (the first side is the machining concave surface, the tooling is about 0.02 mm), and mark the tooth with red paint. Make the concave bouncing cycle (shown below) fixed. 
Of course, the above is the case where the two machine tools process the uneven surface of the small wheel separately. This regularity is also shown when machining the concave and convex surfaces of the small wheel on the same machine tool. For example, the French ZFKK460 machine tool has the same regularity as described above when machining the concave and convex surfaces of other small wheels.
From this, it can be seen that the sequence of cutting operations can improve or stabilize the precision of the cutting wheel.
(1) Before the big wheel is finished, first clean the positioning surface of the big wheel and the positioning surface of the tooling. If you find that there is a small bump on the positioning surface of the big wheel, you should use a trowel to remove the bump.
(2) For the small wheel, it is also necessary to wipe the positioning surface before it can be loaded into the tooling. If it is found that there is a bump in the positioning bearing, the abrasive cloth is used to knock the bump.
According to the cutting principle, the larger the finish allowance, the greater the cutting force and the worse the surface roughness and accuracy after machining. In order to improve the surface roughness of the tooth surface, the large wheel's fine allowance was changed from the original 1.4 mm to 1.6 mm to 1.2 mm to 1.3 mm (double-sided allowance). This further stabilized or improved the gear of the large wheel. Accuracy, radial runout fluctuation range of the ring gear is also stabilized from the original 0.04 mm to 0.11 mm to 0.04 mm to 0.08 mm.
The same measures have been taken for the finishing of the small wheel, changing the double-sided finishing allowance from the original 2 mm to 1.6 mm to 1.8 mm, which also improves the surface roughness of the tooth surface.
(1) During the leveling, change the cold pressure to hot pressure and heat the big wheel to about 80°C.
(2) When testing the flatness of large wheels, not only the measured inner ring does not exceed 0.2 mm, and the outer ring does not exceed 0.1 mm. It also increases the use of a flat ruler to check whether the tooth plane has a convex middle, and it is not allowed to have Convex phenomenon.
For the correction of the BJ130 small wheel, V-blocks are used to support the Y41-40 single-column calibration hydraulic press worktable. The dial indicator is 0.05 mm bevel at the φ45 mm bearing and 0.1 mm at the φ35 mm rear bearing.
In order to better improve the accuracy of gears, we have added items that check the radial runout of the ring gear to be 0.05 mm or less, which has played a very good role in the precision of the heat treatment of the stable wheels.
For users who do not have a T20 pairing machine, the accuracy of the spiral bevel gears is combined in a completely random manner. For the BJ130 spiral bevel gear, the drawings specify that the radial runout of the large gear ring is 0.11 mm, that of the small wheel is 0.065 mm, and the variation of the backlash is 0.15 mm. In order to ensure the accuracy of the product, the specific approach is:
(1) For the BJ130 spiral bevel gear, the big wheel and the small wheel respectively perform all the tests of the radial runout of the ring gear to find out the products with the qualified accuracy of the spiral bevel gear, and then pair them.
(2) In order to improve the matching ratio of the products, the skkz tool adjuster of Origen Company was converted into a ring gear beater to increase the detection rate. After the conversion, one person can measure 150 to 170 BJ130 large wheels. According to the data of the T20 detector, the following rules were found:
ΔFrA - radial runout of large gear ring, mm
ΔFrB - radial runout of small wheel ring, mm
According to formula (1), for the BJ130 spiral bevel gear, ΔFrΣ = 0.175 mm. We categorize the radial runout of the big wheel and the small wheel into six categories as the case may be.
1 (0.14 ~ 0.15) mm + 0.02 mm = (0.16 ~ 0.17) mm, about 10%.
2 (0.12 ~ 0.13) mm + 0.03 mm = (0.15 ~ 0.16) mm, about 20%.
3 (0.09 to 0.11) mm+(0.04+0.07) mm=(0.13 to 0.18) mm, about 60%.
4 (0.05 to 0.08) mm+(0.08+0.10) mm=(0.13 to 0.18) mm, about 5%.
The accuracy of the remaining unsupported vehicles is set at ΔFrΣ≈ 0.18 mm to 0.24 mm, which accounts for about 5%.
After adopting the above comprehensive measures, the small wheel has basically reached a 100% accuracy and qualified matching rate, and the big wheel has reached an accuracy matching qualification rate of about 95%.
(1) Equipped with a roller bearing roller to improve the machine's transmission accuracy.
(2) Improve the tooling structure and improve the positioning accuracy.
(3) Improve the operating method to stabilize the machining accuracy.
(4) Reduce the precision allowance and improve the accuracy of cutting.
(5) Heat press leveling.
(6) Combining matching size gears according to accuracy to improve the passing rate of finished products.