Mon, 16 Jul 2018 02:08:00 +0000

Foil vacuum annealing – heat treatment

High temperature annealing of semi-finished metal materials and finished products is an important process to improve material performance and service reliability. And to avoid oxidation at high vacuum annealing, decarburization and gas, the effect of degreasing, in addition to steel, copper and its alloy, also widely used in titanium, tantalum, molybdenum, niobium, zirconium and gas, such as the strong affinity of rare metal. In order to improve the performance of rare metals, prevent oxidation, meet the needs of modern production, the author designed and manufactured the foil vacuum annealing furnace, used in high vacuum condition, high temperature annealing treatment of the metal foil, sheet, etc, also suitable for steel, copper and its alloy production enterprises and laboratory of colleges and universities, scientific research units, etc.

1. Main technical parameters of the foil vacuum annealing furnace equipment
(1) the effective temperature range of all sizes/mm x mm: Ф 1000 x 3000
(2) the highest temperature heating zone / ℃ : 1050
(3) work / ℃ temperature: 950
(4) mean temperature control precision of temperature region / ℃ : + / – 1
(5) the furnace temperature uniformity / ℃ : + / – 5
(6) ultimate vacuum /Pa: 1.33 * 10-3
(7) working vacuum /Pa: 1.33 * 10-2
(8) pressure rise rate /Pa· h-1:0.67
(9) empty furnace extraction time /min: less than or equal to 30 (from atmospheric pressure to working vacuum during continuous production)
(10) heating power /kW: 420
(11) no-load voltage /V of heating power: 70
(12) layout of heating zone: three zones + compensation at both ends + automatic temperature control at 5 zones
(13) air furnace heating time: rose from room temperature to 950 ℃ or less 3 h
(14) argon protection forced circulation cooling time: from the working temperature of 950 ℃ to 80 ℃ or less time 6 h
(15) compressed air pressure /MPa: 0.4-0.6
(16) rated furnace charge (per furnace) /kg: 1000

2. The composition of the foil vacuum annealing furnace equipment
High temperature and high vacuum heat treatment furnace is the product of modern metallurgical technology, modern vacuum furnace technology, computer and microelectronics technology. Foil vacuum annealing furnace is a high temperature vacuum annealing process for refractory metals, titanium and titanium alloys by using the principle of metal electrothermal radiation. The equipment is mainly composed of hydraulic automatic feeding device, vacuum system, vacuum furnace room, electric heater, inner circulating air cooling system, water cooling system and automatic temperature control system.
3. Main technical difficulties solved
3.1 hydraulic automatic feeding device
Usually, heat treatment furnace feeding device due to heat within the furnace, guarantees of vacuum at the same time, the material requirements are all made of heat resistant steel, such as 0 cr18ni9, 1 cr18ni9ti, expensive, the cost is high. The equipment adopts hydraulic automatic feeding device, which solves the problem of transmission and vacuum seal caused by long-term heat deformation of the feeding vehicle during high temperature annealing. The device adopts a charging and discharging system consisting of an external feed table, an internal support system, a hydraulic feed truck, an orthopedic bottom frame and an orthopedic pressure plate. The feed truck is always in the cold outside the furnace and is not heated inside the furnace. It is made of ordinary carbon steel (Q235), which is low in cost and saves money. At the same time, it reduces the air discharge object in the vacuum chamber, effectively shortens the time of air extraction, and improves the vacuum degree of the equipment.

The hydraulic feeder car is equipped with micro-hydraulic lifting system and automatic walking drive device, which is mainly used for loading and discharging. Considering the production process requirement, to foil (0.2 ~ 0.5 mm) high temperature state school type processing, ensure that the surface roughness, the devices are equipped with special orthopaedic chassis and two pieces of orthopaedic linking piece, as shown in figure 2, all use high temperature resistant steel. In consideration of the long-term high temperature bearing capacity of the furnace support system, heat resistant steel 0Cr25Ni20 is adopted.

Normal work, will need to deal with material placed in orthopaedic chassis, orthopaedic chassis will rise by hydraulic jack, hydraulic to skip, driven by a motor along a fixed loading area outside the furnace and furnace mobile will be sent to the furnace, hydraulic jack fell after orthopaedic chassis on the supporting frame in the furnace, hydraulic to skip come out along the orbit.

3.2 fully automatic control and monitoring of the vacuum system
In the production of vacuum furnace often appear materials is oxidation, especially non-ferrous metals such as titanium, molybdenum materials, prone to oxidation under high temperature, appear the phenomenon such as blue, yellow, serious impact on the performance of materials. The main purpose of the vacuum system is to degassing, maintain the necessary working vacuum, and prevent the material from being oxidized at high temperature. This equipment is equipped with two sets of vacuum units of k-800 high vacuum oil diffusion pump + zj-1200 roots pump + h-150 slide valve pump and two sets of pneumatic valves with opening and closing signals.

The vacuum system consists of digital vacuum gauge full range measurement, touch screen display, automatic switching and control system vacuum, and DMR2100 paperless recorder is used for the whole process record and data storage. All actions of the vacuum system have the function of interlock protection. Interlock requirements: the main valve of the vacuum system is not closed, and the valve cannot be opened. The main valve of the vacuum system cannot be opened because the charging valve is not closed. The vacuum system realizes full automation, effectively enhances the work efficiency, guarantees the production and the security.