If you are a mechanical enthusiast, then you must be full of curiosity and awe of the amazing mechanical element of gears. They act like the heart of a machine, transmitting power and movement between different axes to allow various machines to work properly. But you know what? Making a perfect gear is not an easy task, it needs to be coordinated and optimized by a variety of processes and technologies to achieve the desired effect.

A gear is a disc-shaped object with bulges evenly distributed around it. When the teeth of two or more gears mesh with each other, torque and motion can be transmitted between different shafts. There are many forms of gear shapes, of which involute tooth profiles are the most common. Involute tooth profile refers to the curve of a tooth shape that is formed by a point on the circumference spreading along the normal direction of the circumference. This tooth profile has good meshing performance, which can ensure that the transmission ratio of the two gears is constant.

How do you make a gear? According to different methods, the manufacturing process of gears can be divided into two categories, namely forming method and spreading method. The forming method refers to the cutting or pressing of the gear blank with a tool or mold corresponding to the tooth shape to form a tooth shape. The stretching method refers to rolling or cutting the gear blank with a tool or die equivalent to meshing with the gear to form a tooth shape. Below, we will introduce the specific processes and characteristics of these two methods.

The forming method is a relatively simple and intuitive manufacturing method, which can be used for various types and sizes of gears. Common forming methods are as follows:

Milling teeth: the use of disc modular milling cutter or finger milling cutter milling teeth belongs to the forming method of processing, the cross-sectional shape of the milling cutter teeth corresponds to the shape between the gear teeth. This method has low processing efficiency and processing accuracy, and is only suitable for single-piece small batch production.

Forming and grinding teeth: It is also a forming method, but a grinding wheel is used instead of a milling cutter for cutting. Since grinding wheels are not easy to trim, they are used less.

Casting: Casting is a common gear manufacturing method that allows liquid metal to be poured directly into a mold with toothed grooves to solidify and form. Casting can manufacture large, low-precision, low-strength gears, and can also manufacture complete gears with casting tooth profiles for washing machines, small household appliances, hand tools and other fields.

      Powder metallurgy: Powder metallurgy is a high-precision molding method that is made by placing metal powder into a mold with toothed grooves and then sintering it under high temperature and pressure. Powder metallurgy can manufacture small, high-precision, high-strength spur gears, bevel gears and helical gears for electrical appliances, agricultural machinery, automobiles and other fields.

The development method is a method of manufacturing gears using the principle of meshing, which can achieve high-efficiency and high-precision processing. Common development methods are as follows:

Hobbing: Hobbing is one of the most commonly used gear manufacturing methods besides casting, and it can be used for gears of various types and sizes. Hobbing works like a pair of helical gears meshing, one of which is a gear blank and the other gear is a gear hob. The prototype of the gear hob is a helical gear with a large helix angle, which is grooved and shoveled to become a hob with cutting edge and back angle. When hobbing, the hob and blank carry out circular movement according to a certain transmission ratio, and the hob also carries out axial feed movement, so that an involute tooth shape is formed on the blank.

Shaving: Shaving is a finishing method for non-hardened tooth surfaces, which can improve the accuracy and finish of the tooth surface, and can also form drum teeth to improve the position of the contact zone of the tooth surface. The working principle of shaving teeth is to use the shaving cutter and the processed gear for free meshing motion, with the help of the relative slip between the two, shave very fine chips from the tooth surface. The prototype of the shaving knife was a helical gear with a small helix angle, which was grooved and shoveled to become a razor with cutting edge and back corner. When shaving, the razor and the blank carry out circular movement according to a certain transmission ratio, and the razor also reciprocates, so that an involute tooth shape is formed on the blank.

Shaping teeth: Shaping is a tooth cutting process using the development method, which can be used for spur gears, helical gears, bevel gears, etc. When shaping, the gear shaping cutter and the workpiece are equivalent to the meshing of a pair of cylindrical gears. The prototype of the shaping knife is a cylinder with a straight or curved number of grooves, which become a cutting edge and a back corner after the number of grooves and grooves. When shaping, the inserting tool reciprocates along the axis of the workpiece, which is the main movement of the shaping of the teeth; At the same time, the circular motion of the insertion tool and the workpiece in a certain proportion is the feed movement of the shaping teeth.

Gears are a very important mechanical element that plays an indispensable role in various machines. Making a perfect gear is not a simple matter, it needs to choose the right process and technology according to different needs and conditions to achieve the desired effect.