Vacuum oxygen-free heating furnace and hot stamping production line and hot stamping method thereof

Abstract

The invention discloses a vacuum oxygen-free heating furnace. The vacuum oxygen-free heating furnace is characterized in that the vacuum oxygen-free heating furnace comprises a hot zone, a first opening and closing mechanism, a second opening and closing mechanism and a conveying mechanism. The first opening and closing mechanism is arranged between the hot zone and a cold zone. The conveying mechanism is used for conveying a workpiece between the cold zone and the hot zone when the first opening and closing mechanism is in an open state. The second opening and closing mechanism is arranged onthe cold zone, and is in a closed state when the first opening and closing mechanism is in an open state. The hot zone and the cold zone are correspondingly provided with a pressure adjusting systemcapable of enabling the hot zone and the cold zone to be in a vacuum oxygen-free environment. The vacuum oxygen-free heating furnace ensures that a material sheet is in a vacuum oxygen-free environment in the heating process, oxide coatings are prevented from being generated during bare plate forming, a mold is protected against wear and drawing, and the service life of the mold is prolonged; andmeanwhile, an original shot blasting process is omitted, the production cycle is shortened, the cost is saved, and the bare plate part quality is improved.

Description

technical field [0001] The invention relates to a vacuum anaerobic heating furnace, a hot stamping production line and a hot stamping method using the vacuum anaerobic heating furnace. Background technique [0002] At present, there are generally two types of high-strength steel materials in the automotive hot stamping industry, 22MnB5 coated plate and bare plate. The bare plate is used more and more because of its cheap price. Because the bare plate will produce oxide scale after heating, the oxide scale is mainly composed of suboxide Composed of iron, ferroferric oxide and ferric oxide, it is brittle and has no extensibility. Under mechanical action and thermal processing, it is easy to crack and detach. Therefore, when the bare board is formed on the mold, the The oxide scale will increase the friction between the steel plate and the mold, increase the wear of the mold, and reduce the service life of the mold. At the same time, the generation of oxide scale will reduce th...

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Problems solved by technology

[0002] At present, there are generally two types of high-strength steel materials in the automotive hot stamping industry, 22MnB5 coated plate and bare plate. The bare plate is used more and more because of its cheap price. Because the bare plate will produce oxide scale after heating, the oxide scale is mainly composed of suboxide Composed of iron, ferroferric oxide and ferric oxide, it is brittle and has no extensibility. Under mechanical action and thermal processing, it is easy to crack and detach. Therefore, when the bare board is formed on the mold, the The oxide scale will increase the friction between the steel plate and the mold, increase the wear of the mold, and reduce the service life of the mold. At the same time, the generation of oxide scale will reduce the formability of the steel plate and cause strain; and the thermal conductivity of the scale is very low. , which seriously affects the heat transfer between the steel plate and the mold

[0003] In order to suppress the oxidation of the bare board, the existing production process is to pass inert gas into the radiation heating furnace to reduce the oxygen content, but the industrial furnace has a large space, the atmosphere establishment period is very long, and the furnace door will be opened and closed online. The oxygen content in the furnace cannot be reduced to infinitely low, and the low oxygen environment can only slow down the oxidation speed of the bare board at high temperature, but cannot prevent the formation of scale, especially when the furnace gas is not mixed uniformly, the oxidation of the bare board will be aggravated, The surface quality of the bare board after thermoforming can never reach the surface quality effect of the coated board after thermoforming, so there is a shot blasting and oil spraying process after the bare board is thermoformed, the purpose is to remove the oxide scale generated during thermoforming

[0004] At present, most of the vacuum heating furnaces on the market are cold furnace charging / cold furnace discharging, and this method of heating furnace cannot meet the industrial continuous production; when using a continuous vacuum furnace, due to high temperature discharge, many parts of the furnace are at high temperature In this state, the cold blanks entering the furnace will be heated instantly, and the air in the furnace is not pumped out at this time, so the risk of the blanks being oxidized is greatly increased at this time

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