Basin angle tooth production and processing

Basin angle tooth production and processing

Gear blank processing

The rough machining of gears plays an important role in the whole gear processing. The reference used for the machining and testing of the tooth surface must be processed in the machining stage of the gear blank. At the same time, the machining time of the blank machining has a large proportion, which has a great influence on the production efficiency and the quality of the gear processing. Too much margin will lead to the subsequent semi-finishing. The amount of processing required for processing and finishing increases, time-consuming increases, and production efficiency is reduced; if the margin is too small, subsequent processing requires special care, otherwise the gear design accuracy size will be exceeded and the product will be unqualified. Therefore, special attention needs to be paid to the gear blank processing stage.

Tooth surface processing

There are many methods for tooth surface machining, including hobbing, gear shaping, shaving, grinding, milling, gearing, combing, squeezing, grinding and caries, among which the first four methods are used. : hobbing, gear shaping, shaving and grinding.

1, hobbing

The hobbing gear is a development method that can be used to drive gears and racks with no meshing clearance. When the hobbing rotates one revolution, it corresponds to the movement of the rack in the normal direction. The continuous transmission of the hob is like an infinitely long rack moving continuously. When the hob and the hobbing blank are forcedly meshed according to the gear ratio of the gear to the rack, the envelope of the hob teeth in a series of positions forms the involute profile of the workpiece. With the vertical feed of the hob, the desired profile can be rolled out. Hobbing is currently the most widely used method of cutting teeth. It can process involute gears, arc gears, cycloidal gears, sprockets, ratchets, worm gears and enveloping worms. The precision can generally reach DIN4~7. At present, the advanced technologies of hobbing include: (a) multi-head hob hobbing; (b) hard-tooth hobbing technology; (c) large gear hobbing technology; (d) high-speed hobbing technology.

2, the tooth

The gear teeth are particularly suitable for machining internal gears and multiple gears. With special tools and accessories, it can also process silent sprocket, ratchet, internal and external spline, toothed pulley, sector gear, non-complete tooth gear, special tooth combination, rack, face gear and taper gear. At present, the advanced gear shaping technology includes: (a) multi-cutter gear insertion technology; (b) microcomputer numerically controlled gear shaping machine; and (c) hard tooth surface gear insertion technology.

3, shaving teeth

The shaving process is based on the principle of a pair of helical gears with different helix angles. The shaving cutter intersects the axis space of the cut gear at an angle, and their meshing is a free-form motion without double-sided meshing. Shaving is a high-efficiency gear finishing method. Compared with grinding teeth, shaving has the advantages of high efficiency, low cost, no burns on the tooth surface and cracks. Therefore, it has been widely used in the processing of gears such as automobiles, tractors and machine tools. The diagonal shaving method and the radial shaving method can also be used for finishing with shoulder gears.

4, grinding teeth

Grinding is the most efficient and reliable way to obtain high precision gears. In developed countries, hard-toothed gears have been used, and grinding has become the main processing method for high-precision gears. At present, the grinding accuracy of the disc-shaped grinding wheel and the large-surface grinding wheel can reach DIN2, but the efficiency is very low. The grinding precision of the worm wheel is up to DIN3~4, and the efficiency is high. It is suitable for medium and small modulus gear grinding, but the grinding wheel correction is more complicated. The main problem with grinding teeth is low efficiency and high cost, especially for large gears. Therefore, improving the grinding efficiency and reducing the cost is the current main research direction. In recent years, new technologies in grinding have: (a) double-sided grinding; (b) high-efficiency grinding of cubic boron nitride grinding wheels; (c) continuous forming grinding technology and ultra-high speed grinding technology.

5, milling teeth

The milling gear is a forming method for machining the gear. The cutting shape of the tool is the same as the shape of the tooth groove of the gear to be machined. The tool feeds in the direction of the tooth groove of the gear, and one tooth groove is milled. After the gear is indexed, the second is milled. The cogging, the tooth pitch of the gear is controlled by the indexing. Since the shape of the tooth groove of the gear is related to the number of teeth of the gear, the correction amount, and even the tooth thickness tolerance, the forming method is difficult to achieve the same tooth profile and the gear groove of the machined gear. In fact, the milling gear is mostly approximate to the tooth profile. Large-modulus gears have high production efficiency, and milling cutters are widely used for rough cutting.

6, planing teeth

The gear teeth are generally used to machine the tooth faces of spur gears, bevel gears or racks with a gear cutter. The planing knives have two movements: one is the linear cutting reciprocating motion of the planing knives; the other is the planing rotary motion of the planing knives with the cradle, the movement relationship between the knives and the bevel gears being processed, equivalent to the teeth of a flat top or face gear and the bevel being machined Engagement of the gears. The tool is turned into a cutting tooth once, and one tooth is machined. After the machined bevel gear is indexed, the second tooth is machined.

7, comb teeth

The comb is a cylindrical gear that is inserted with a rack knife. It is characterized by high machining accuracy and can reach DIN5. Due to the simple structure of the cutter, convenient manufacturing and sharpening, high precision and many times of sharpening, it is convenient to use hard alloy blades and cubic boron nitride blades to process hardened gears. [2] 

finishing

At present, the gear finishing methods for industrial applications are mainly shaving, grinding, squeezing, grinding and caries.

Shaving is a method of shaving with a shaving cutter on a shaving machine. It is a method of gear finishing. The shaving cutter is equivalent to a helical gear with many blades on the tooth surface. It drives the relative rotation of the machined gears, as the staggered shaft gears mesh, and the relative sliding on the tooth surface, the shaving cutter cuts a thin layer of metal on the tooth surface to complete the gear finishing, the adjustment of the shaving machine slide Ensure that the gear teeth are machined correctly. The accuracy of shaving is limited by the accuracy of the shaving of the front teeth. The shaving production efficiency is high, suitable for hobbing and soft tooth surface finishing after gear shaping.

Grinding the teeth is to grind the tooth surface with a grinding wheel. The grinding tooth can grind the hardened gear of the tooth surface, eliminate the heat treatment deformation and improve the gear precision. According to the different grinding wheels used, the grinding teeth are divided into: (1) tapered grinding wheel grinding; (2) butterfly grinding wheel grinding; (3) large flat grinding wheel grinding; (4) worm grinding wheel grinding; (5) Involute enveloping toroidal worm wheel grinding teeth; (6) forming grinding wheel grinding teeth.

Both the teeth and the teeth are the means of gear finishing. Extrusion is the use of the squeeze wheel to squeeze the tooth surface of the machined gear to improve the surface quality of the gear. It is mainly suitable for the finishing of the soft tooth gear after hobbing and gear insertion. The molars are basically the same as the method of shaving, that is, the shaving cutter is replaced with the honing wheel of the same shape, and the tooth surface is polished by the relative sliding with the tooth surface, and the tooth surface of the processed gear can be soft and hard.