Commonly Used Sprocket and Gear Machining Methods: 1. Form Milling: This milling method belongs to the form milling method. During milling, the workpiece is mounted on the indexing head of the milling machine, and a disc (or finger) milling cutter with a certain module is used to mill the spaces between the gear teeth. After machining one space, indexing is performed, and then the next space is milled. Characteristics of milling: simple equipment; low tool cost; low productivity; low gear machining accuracy. The tooth profile shape of the gear is determined by the size of the base circle (related to the number of teeth of the gear). The motion required for milling gears using the form milling method is simple, and no special machine tool is needed, but an indexing head is required for indexing, resulting in low production efficiency. This method is generally used for single-piece, small-batch production of low-precision gears. 2. Generating Milling: When machining gears using the generating milling method, the involute on the gear surface is formed by generating. The generating milling method has higher production efficiency and machining accuracy. Most gear machining machines use the generating milling method. 1) Hobbing…

There are two common principles for gear machining: contour machining and generating machining. 1. Contour Machining: The gear machining tool cuts out the tooth grooves of the gear; the "cross-sectional shape" of the tool is the shape of the gear tooth grooves. During gear machining, there is no gear meshing motion, resulting in low precision, generally below grade 11. 2. Generating Machining: The gear machining tool itself is a "gear or rack." A gear hob can be considered a rack and belongs to the rack-type tool category. During machining, there is a "gear meshing" motion between the gear machining tool and the gear being machined. The cutting edge of the gear machining tool's tooth profile envelopes the tooth profile (tooth surface) of the gear being machined, forming an ideal involute curve. Machining precision is high; common examples include hobbing, shaping, and shaving (belonging to finish machining).

Racks are also divided into spur racks and helical racks, which are paired with spur gears and helical gears respectively. The tooth profile of a rack is a straight line rather than an involute (it is a plane with respect to the tooth surface), equivalent to a cylindrical gear with an infinite pitch circle radius. The main characteristics of a rack are: 1. Because the rack tooth profile is a straight line, all points on the profile have the same pressure angle, which is equal to the inclination angle of the profile. This angle is called the tooth profile angle, with a standard value of 20°. 2. Any straight line parallel to the addendum line has the same tooth pitch and module. 3. The straight line parallel to the addendum line and whose tooth thickness is equal to the tooth space width is called the pitch line (center line), which is the reference line for calculating the rack dimensions. The main parameters of a rack include: tooth space width, addendum, dedendum, tooth height, tooth thickness, and root circle radius.

Racks are divided into spur racks and helical racks, which are paired with spur gears and helical gears respectively. The tooth profile of a rack is a straight line rather than an involute (it is a plane for the tooth surface), equivalent to a cylindrical gear with an infinite pitch circle radius. Main characteristics: 1. Because the rack tooth profile is a straight line, all points on the profile have the same pressure angle, which is equal to the inclination angle of the profile; this angle is called the tooth profile angle. 2. Any straight line parallel to the addendum line has the same tooth pitch and module. 3. The straight line parallel to the addendum line and with a tooth thickness equal to the tooth space width is called the pitch line (center line), which is the baseline for calculating rack dimensions. Parameter selection: 1. Whether the gear runout, total tooth depth, common normal, and tooth direction are acceptable; whether the single-tooth runout and periodic pitch error exceed the tolerance. 2. Whether the installation distance after gear and rack installation is appropriate. 3. The meshing clearance of the rack and gear should be 0.25 times the module. 4. The rack's total tooth depth, runout, common normal, and tooth direction…

A large-module rack and pinion mechanical sprocket is a toothed wheel-shaped mechanical part that meshes with a chain to achieve its function. With the continuous development of our industry, the application of sprockets is becoming increasingly widespread. A mechanical sprocket is also a solid or spoked gear that meshes with a (roller) chain to transmit motion. Mechanical sprockets are used in industries such as chemical engineering, textile machinery, food processing, instrumentation, and petroleum. The chain can smoothly enter and exit the meshing with the sprocket teeth. The mechanical sprocket teeth are evenly stressed, making them less prone to chain slippage. The tooth profile is easy to machine. The national standard GB/T1234-1997 only specifies the shape and limit parameters of the tooth grooves on the large and small end faces (ui and z), and that the curves forming the tooth grooves should be smoothly connected, without specifying a specific tooth profile. Many standard tooth profile curves can meet these requirements; the most commonly used now is the "three circular arcs and one straight line" tooth profile.

Racks are one of the most important basic transmission components in gear transmission devices. Their load-bearing capacity and service life are important indicators of the level of rack manufacturing technology. Currently, large-module racks in mining equipment and metallurgical equipment such as forging and rolling mills have tooth profile accuracy of grades 8 and 9 (medium precision) according to national standard (GB1009-88), tooth surface hardness of HB (350) (medium hardness), and a tooth surface roughness Ra requirement of 3.2-1.6 μm. Milling is perfectly capable of meeting the product design drawing requirements for the finishing of these large-module racks. In recent years, hard-tooth-surface racks have appeared in some special products. These racks have tooth profile accuracy equivalent to grades 7 and 8 (higher precision) of national standard (GB1009-88), tooth surface hardness of HRC55 or higher, and a tooth surface roughness Ra requirement of 0.8 μm. For large-module hard-tooth-surface racks…

The meshing principle of staggered-axis helical gears is widely used in gear machining and measurement. Its characteristic is that the gear pair satisfies the point meshing principle. The contact trace is the set of instantaneous meshing points on its profile, reflecting the essential property of point meshing in staggered-axis helical gears. Using circular vector functions and the intermediate rack as tools, the contact trace equation is derived, and the characteristics of the contact trace are discussed. This reveals the essence of gear machining and measurement based on the point meshing principle and elucidates the application of contact traces in gear machining and measurement.