Materials and applications of gear steel and gears
1、Gear Steel And Gears is the steels that can be used to process and manufacture gears
All steels that can be used to process gears can be called gear steel. Because gears bear external loads by relying on their own structural size and material strength, the steels for manufacturing gears are required to have high strength, hardness, toughness, wear resistance and manufacturability.
With the development of technology, is developing in the direction of high performance, long service life, stable gear operation, low noise, safety, low cost, easy processing and multiple varieties.
In terms of performance indicators, there are three main standards to measure the performance of gear steel:
mainly to ensure the core hardness of gears of different sizes, and is conducive to controlling the heat treatment deformation of gears. Its performance mainly depends on the chemical composition and its uniformity.
Oxide and sulfide inclusions and harmful elements will reduce the mechanical properties of the steel and affect the service life of the gear. Therefore, the oxygen content of general gear steel is required to be controlled at 20 × Below 10-6.
(3). Grain size
The grain size index can improve the fatigue performance of gear and reduce the deformation of gear after heat treatment. Generally, the grain size of gear steel is required to be ≥ grade 6, mainly by controlling the residual aluminum content in the steel during smelting.
3、 What are the Gear Steel And Gears materials
The commonly used materials of gear steel include forged steel and cast steel. Cast steel is generally used to manufacture gear with diameter greater than 400mm, complex structure and unsuitable for forging. Other conditions are more suitable for forged steel. The forged steel used is also different according to the hardness of tooth surface:
(1). Soft tooth surface
The hardness of tooth surface less than 350mm is called soft tooth surface. The commonly used gear steels for soft tooth surface include 45# steel, 35SiMn, 40Cr, 40crni and 40MnB.
(2). Hard tooth surface
Gear surface with hardness greater than 350mm is called hard gear surface.
Gear steel used for hard gear surface can be divided into medium carbon steel and low carbon steel. Medium carbon steel includes 35# steel, 45# steel, 40Cr, 40crni, 42CrMo, 35CrMo, etc., and low carbon steel includes 20Cr, 20CrMnTi, 20mnb, 20crmnto, etc.
Principle of gear
Gear is a kind of power transmission parts. Through the meshing of gears with the same module, the power is transmitted from shaft a to shaft B to complete the power transmission.
Gear transmission has the advantages of high transmission precision, wide application range, high transmission efficiency and long service life.
Function of gear
The main function of gears is to transmit power. In addition to being used as production parts of watches and alarm clocks, gears also have great applications in the field of heavy industrial manufacturing.
Type and name of gear
Classify gears according to their axial properties
1. Parallel shaft gear: spur gear, helical gear, internal gear, rack and helical gear, etc.
2. Intersecting shaft gear: spur gear, spiral bevel gear, zero tooth, bevel gear, bevel gear, etc.
3. Staggered shaft gear: there are staggered shaft helical gear, worm gear, hypoid gear, etc.
4. Special shaft gear: face gear, harmonic gear, cycloid gear, etc.
According to the material classification of gear steel and gears
1. Metal gears: forged steel gears, cast steel gears, cast iron gears, etc.
2. Non metallic gears: Nylon gears, cloth gears, wooden gears, plastic gears, etc.
What are the basic parameters of gears
Number of teeth Z: the number of teeth refers to the total number of teeth of a gear.
Modulus M: modulus refers to the ratio of pitch P and PI between the tooth profiles on the same side of two adjacent gears. The larger the modulus of gears with the same number of teeth, the larger the size.
Indexing circle diameter D: the indexing circle diameter refers to the circle whose diameter is the product of modulus multiplied by the number of teeth. The tooth size of gear is determined based on this circle.
pressure angle α： At the tangent point P of the two gear pitch circles, the acute angle between the common normal of the two tooth profile curves and the common tangent of the two pitch circles is called the pressure angle, also known as the meshing angle.
Tooth height and tooth thickness: the height of the tooth is determined by the module M. full tooth height = tooth root height + tooth top height, where tooth top height is the height from the tooth top to the dividing line, and tooth root height is the height from the tooth root to the dividing line. The datum of tooth thickness is half of the tooth pitch.
Gear machining principle
1. Forming method: use the cutting edge to cut the shape on the gear groove to be cut, and the machining accuracy is low.
2. Generating method: using the envelope of the motion path of the cutting edge of the tool to cut the gear, the machining accuracy and productivity are high.
Gear processing equipment
Common gear processing machine tools include gear planer, gear milling machine, gear drawing machine, gear shaper, gear turning machine, bevel gear milling machine, etc.
Detection method of gear
Gear detection methods include gear single geometry error measurement technology, gear comprehensive error measurement technology, gear overall error measurement technology, gear on-machine measurement technology and gear laser measurement technology.
What measuring tools are needed for gear inspection
1. Measuring gear indexing: tooth thickness vernier caliper, optical tooth thickness caliper and various tooth thickness chucks, etc.