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HT250 heat treatment brake drum and fabrication method thereof

A brake drum and process technology, applied in heat treatment equipment, heat treatment furnace, brake drum, etc., can solve problems such as brake drum thermal fatigue cracking, bottoming accidents, brake drum rapid wear, etc., to overcome thermal fatigue cracking life Insufficient, improve the casting yield, the effect of strength improvement

Active Publication Date: 2021-07-13
DONGFENG COMML VEHICLE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The embodiment of the present invention provides a HT250 heat-treated brake drum and its preparation method to solve the problem that the gray iron brake drum in the related art often causes rapid wear of the brake drum due to insufficient hardness, and the brake drum is repeatedly rubbed and heated due to insufficient strength. Thermal fatigue cracking, prone to bottoming accidents after crack expansion, etc.

Method used

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  • HT250 heat treatment brake drum and fabrication method thereof
  • HT250 heat treatment brake drum and fabrication method thereof
  • HT250 heat treatment brake drum and fabrication method thereof

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preparation example Construction

[0026] The embodiment of the present invention provides a preparation method of HT250 heat-treated brake drum, comprising the following steps: providing a preparation method of HT250 heat-treated brake drum, comprising the following steps: adopting induction hardening process, first finishing the surface of HT250 brake drum Heat to 860-920°C, and then continuously spray quenching liquid on the surface of HT250 brake drum precision workpiece until the surface temperature is not higher than 100°C; then place HT250 brake drum precision workpiece at 500-550°C for tempering a lot After 2 hours; finally, place the finished piece of HT250 brake drum in the air and cool it down to room temperature naturally to obtain HT250 heat-treated brake drum.

[0027] The invention adopts HT250 material with high casting yield and good heat dissipation performance to prepare HT250 brake drum precision parts. The surface hardness and tensile strength of the HT250 brake drum precision parts are enha...

Embodiment 1

[0040] The present embodiment provides a kind of HT250 brake drum fine work piece, and its preparation method is as follows:

[0041] (1) Material selection: select HT250 raw materials that meet the requirements of national standards, and the commonly used main chemical components are as follows in terms of weight percentage;

[0042] C Si mn P S 3.3±0.1 1.9±0.1 0.7±0.05 ≤0.1 0.06±0.05

[0043] The rest is Fe and other unavoidable impurities.

[0044] (2) Casting and processing: According to the national standard GB / T 9439-2010, the HT250 raw material is melted in an electric furnace and cast into a HT250 brake drum rough billet, and then roughed and finished, and a qualified HT250 brake drum is processed. Precision workpiece, its metallographic structure is thicker flaky pearlite + ferrite + flake graphite + carbide.

Embodiment 2

[0046] This embodiment provides a method for preparing a HT250 heat-treated brake drum, comprising the following steps:

[0047] (1) induction hardening

[0048] A multi-turn inductor is used to heat the inner circular surface of the HT250 brake drum precision workpiece provided in Example 1, and at the same time, the HT250 brake drum precision workpiece is rotated to ensure that the inner circular surface is evenly heated; wherein, the frequency of the induction heating current is set to 8kHz , the heating specific power is 1kW / cm 2 , The heating time is 40 seconds. When the inner surface of the HT250 brake drum precision workpiece is heated to 860°C, spray the quenching liquid immediately, and stop spraying the liquid when the inner surface of the HT250 brake drum precision workpiece cools to 100°C; among them, the quenching liquid is PAG with a concentration of 8wt%. quenching agent.

[0049] (2) High temperature tempering

[0050] Put the quenched HT250 brake drum into...

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Abstract

The invention discloses an HT250 heat treatment brake drum and a fabrication method thereof. The fabrication method comprises the following steps that an induction quenching technology is adopted, the surface of an HT250 brake drum fine workpiece is heated to 860-920 DEG C, and then quenching liquid is continuously sprayed to the surface of the HT250 brake drum fine workpiece till the surface temperature of the HT250 brake drum fine workpiece is not higher than 100 DEG C; then the HT250 brake drum fine workpiece is placed at the temperature of 500-550 DEG C to be tempered for not less than 2 hours; and finally, the HT250 brake drum fine workpiece is placed in air to be naturally cooled to the room temperature, and the HT250 heat treatment brake drum is obtained. The HT250 brake drum before and after heat treatment is examined on a special brake drum thermal fatigue test bench, and the average values of thermal fatigue cracking service life are 86 times and 375 times respectively; and the HT250 brake drum is assembled on a vehicle for a mountain road test, and the average service life mileage before and after heat treatment is about 20,000 km and 55,000 km, so that the service life of the brake drum is greatly prolonged.

Description

technical field [0001] The invention relates to the automobile manufacturing industry, belongs to the technical field of brake system component manufacturing, and in particular relates to a HT250 heat-treated brake drum and a preparation method thereof. Background technique [0002] At present, the brake drums of medium and heavy commercial vehicles are mostly made of gray cast iron, which has high thermal conductivity, heat dissipation, wear resistance and good casting performance. However, when used in mountainous areas, the long downhill mileage at one time often reaches 40 kilometers, which makes the service conditions of the brake drum very bad, and the failure mileage is concentrated at about 20,000 kilometers, causing a large economic burden to users. At present, the main solution to this problem is to install a hydraulic retarder, and some users have even installed a brake king, that is, to install an air distribution valve to increase the braking force, or to instal...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/00C21D1/10F16D65/10
CPCC21D9/0068C21D1/10F16D65/10Y02P10/25Y02P10/20
Inventor 赵俊平吴永强樊晓光余金科鲁福来牛恩来戴勇
Owner DONGFENG COMML VEHICLE CO LTD
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