阅读说明：本技术 一种20SiMnVB制动蹄滚轮轴的加工方法 (Processing method of 20SiMnVB brake shoe roller shaft ) 是由 梁宏军 于 2018-08-29 设计创作，主要内容包括：本发明公开了一种20SiMnVB制动蹄滚轮轴的加工方法,属于机件加工技术领域,依次包括以下步骤：下料、退火、抛丸处理、软化处理、挤压、粗车、精车、渗碳处理、预冷淬火、低温回火、二次抛丸、精磨；本发明通过二次升温和降温预冷淬火,两次回火,能有效细化晶粒,细化马氏体针,降低表层残余奥氏体含量,使高合金渗碳钢齿轮力学性能得到大幅改善,塑韧性指标明显提高。(The invention discloses a method for processing a 20SiMnVB brake shoe roller shaft, which belongs to the technical field of machine part processing and sequentially comprises the following steps of: blanking, annealing, shot blasting, softening, extruding, rough turning, finish turning, carburizing, precooling and quenching, low-temperature tempering, secondary shot blasting and fine grinding; according to the invention, through secondary heating, cooling, pre-cooling and quenching and secondary tempering, crystal grains can be effectively refined, martensite needles can be refined, the content of residual austenite on the surface layer can be reduced, the mechanical property of the high-alloy carburizing steel gear can be greatly improved, and the plastic toughness index can be obviously improved.)

1. A processing method of a 20SiMnVB brake shoe roller shaft is characterized by sequentially comprising the following steps: blanking, annealing, shot blasting, softening, extruding, rough turning, finish turning, carburizing, precooling and quenching, low-temperature tempering, secondary shot blasting and fine grinding;

the pre-cooling quenching comprises the following steps:

1) heating the carburized brake shoe roller shaft to 890 +/-10 ℃ along with a furnace, and preserving heat for 2-3 h;

2) rapidly cooling to 750 +/-10 ℃, and preserving heat for 3-4 h;

3) and rapidly heating the brake shoe roller shaft to 820 +/-10 ℃ for the second time, and keeping the temperature for 2-3 hours.

2. The method of machining a 20SiMnVB brake shoe roller shaft of claim 1 wherein the low temperature tempering includes the steps of: heating the pre-cooled and quenched brake shoe roller shaft to 490 +/-10 ℃ along with a furnace, preserving heat for 6 hours, and discharging and cooling with oil.

3. The method for processing the 20SiMnVB brake shoe roller shaft according to claim 2, wherein after oil cooling, the brake shoe roller shaft is tempered once again at low temperature in an environment of 160 +/-10 ℃, is kept for 3-4 h, is taken out of a furnace and is cooled to room temperature in an air cooling mode.

4. The method of machining a 20SiMnVB brake shoe roller shaft of claim 1, wherein the softening process comprises the steps of: and (4) deoiling, softening, neutralizing, adjusting and cleaning the blank subjected to shot blasting.

5. The method for machining a 20SimnVB brake shoe roller shaft according to claim 1, wherein the blanking raw material is 20SiMnVB round steel.

6. The method of machining a 20SiMnVB brake shoe roller shaft of claim 1 wherein said annealing includes the steps of: and (3) placing the blank into an industrial electric furnace for annealing treatment, heating the blank to 850 +/-50 ℃ in the furnace, preserving the heat for 5-7h, and cooling along with the furnace.

Technical Field

The invention relates to the technical field of machining of machine parts, in particular to a machining method of a 20SiMnVB brake shoe roller shaft.

Background

The vehicle brake is an important part of the vehicle and is the key for ensuring the driving safety. Currently used vehicle brakes include drum brakes and disc brakes. The drum brake widely used in domestic trailers, semitrailers and trucks at present consists of a brake bottom plate, brake shoes, friction linings, brake shoe supporting pins, a cam shaft, a return spring, an adjusting arm, a tension spring, a roller shaft, rollers and other parts. When the brake is stepped, the cam curved surface of the cam shaft pushes the roller to open the brake shoe, and a friction lining on the brake shoe is contacted with the inner cylindrical surface of the rotating brake drum to generate a friction resistance distance to implement braking.

In the prior art, the roller shaft is complex in structure, generally made of 45# round steel through hot forging and machining, complex in forging process and low in production efficiency, and particularly, each surface of a part needs to be machined after forging, so that the machining amount is large, and the production cost of the product is very high. Some factory tests adopt an extrusion process for processing, but due to the factors of unreasonable process design, overlarge deformation and the like, a large number of cracks exist on the surface of a product, and a qualified product cannot be obtained.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a processing method of a 20SiMnVB brake shoe roller shaft, which can effectively refine crystal grains, refine martensite needles and reduce the content of residual austenite on the surface layer by secondary heating, cooling, precooling and quenching and secondary tempering, so that the mechanical property of a high-alloy carburizing steel gear is greatly improved, and the ductility and toughness index is obviously improved.

A processing method of a 20SiMnVB brake shoe roller shaft sequentially comprises the following steps: blanking, annealing, shot blasting, softening, extruding, rough turning, finish turning, carburizing, precooling and quenching, low-temperature tempering, secondary shot blasting and fine grinding;

the pre-cooling quenching comprises the following steps:

1) heating the carburized brake shoe roller shaft to 890 +/-10 ℃ along with a furnace, and preserving heat for 2-3 h;

2) rapidly cooling to 750 +/-10 ℃, and preserving heat for 3-4 h;

3) and rapidly heating the brake shoe roller shaft to 820 +/-10 ℃ for the second time, and keeping the temperature for 2-3 hours.

Further, the low temperature tempering comprises the following steps: heating the pre-cooled and quenched brake shoe roller shaft to 490 +/-10 ℃ along with a furnace, preserving heat for 6 hours, and discharging and cooling with oil.

Further, after oil cooling, tempering the brake shoe roller shaft at low temperature once again in an environment of 160 +/-10 ℃, preserving heat for 3-4 hours, discharging from the furnace and air cooling to room temperature.

Further, the softening treatment comprises the following steps: and (4) deoiling, softening, neutralizing, adjusting and cleaning the blank subjected to shot blasting.

Furthermore, the raw material for blanking is 20SiMnVB round steel.

Further, the annealing comprises the following steps: and (3) placing the blank into an industrial electric furnace for annealing treatment, heating the blank to 850 +/-50 ℃ in the furnace, preserving the heat for 5-7h, and cooling along with the furnace.

Compared with the prior art, the invention has the beneficial effects that: the material utilization rate is improved, the process flow is reduced, and the processing time is saved. Meanwhile, the mechanical property of the whole part is greatly improved, crystal grains can be effectively refined, martensite needles can be refined, the content of residual austenite on the surface layer is reduced, the mechanical property of the high-alloy carburizing steel gear is greatly improved, the ductility and toughness index is obviously improved by two times of tempering, and meanwhile, the wear resistance of the surface of the high-alloy carburizing steel gear is also greatly improved, so that the fatigue strength and the corrosion resistance of the gear are also improved, and the comprehensive mechanical property of the gear is improved.

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.