Artificial heat ageing process rules

According to thermal aging process rules and the characteristics of my company require high precision castings, operating procedures are formulated for the 1. The preparing work before aging a) Castings shall be cleaned before aging, can not have sundry b) Check each part of the furnace, flue, air duct, gate car, blower, drag the organization is normal. c) Calibration of each measuring point thermocouple instrument, make its in normal working condition. d) According to the characteristics of ready to pad iron, castings, tooling 2. Furnace charging a) Each furnace charging to the casting thickness, complex coefficient close to help choose the appropriate process parameters. b) Should grasp the big not small pressure, light weight don't pressure principle. c) Emissions and support 1 of castings. Casting evenly heat and furnace gas emissions should be conducive to the normal circulation. 2. Key-module, key surface shall not put the casting, such as lathe bed guide rail surface 3. To prevent caused by weight of workpiece deformation, stress, adding new shim maximum offset is not more than a third of maximum width of castings, the shim not staggered up and down when 4 layer. Casting from car surface is not less than 100 mm from the top is not less than 400 mm, casting layer spacing not less than 50 mm, and the distance between adjacent casting is not less than 100 mm, casting away from the door not less than 200 mm5. Put on the pad iron castings to smooth and neat, is not high, not ultra wide 6. After inspection personnel inspection, inspection station sand sealing after normal start car entering the furnace; Furnace wall and the alignment, gaps with asbestos or mudding yan 7. A) the heating, insulation, cooling Axis heating, heat preservation, cooling process as shown in the above b) Casting charging temperature shall not exceed 200 ℃, the heating rate is not greater than 100 ℃ / hour, if the workbench, shells and other chores, heating speed should be less than 60 ℃ / hour, in the process of heating up the three measuring point temperature difference should be less than 100 ℃ c) Heat preservation, heat preservation time generally for 5 hours, such as large amount of furnace heat preservation time should be appropriately extended, in the process of insulation three temperature measuring point temperature difference should be controlled within 60 degrees d) Cooling, the temperature should be controlled under 70 ℃ / hour, if less chores cooling control under 50 ℃ / hour. Below 200 ℃ can come e) In order to facilitate inspection analysis, burning furnace should be truthfully fill in the condition of thermal aging on the process of recording, and recording paper with 8 inspection personnel to save for future reference. From a) Before taking thermocouple in order to avoid damage. b) The winter came second, drag a car 9 every 30 minutes. Especially big oven aging after unloading furnace, should inform the inspection personnel, according to the relevant provisions of the inspection signature rear can into 10 next procedure. A) production safety Electrical and mechanical parts operations, the implementation of related procedures. b) Work finished in time clean up the aging furnace surrounding flammable items, turn off the total power d) Eliminating stress tempering treatment ( Artificial aging) Eliminating stress is to remove some parts are produced after rough machining stress caused by stress and after straightening, to ensure the accuracy of stability and provided a basis for heat treatment to reduce the deformation of next working procedure. 1. Eliminate machining stress aging temperature is in commonly 120 - Insulation between 180 ℃ and 4 ~ - 6 hours, and its purpose is to stability of residual austenite and the reduction of mechanical stress, the size stability. Our factory grinding wheel spindle 38 crmoal is an exception, the aging temperature is 240 plus or minus 10 ℃, insulation - 6 12 hours. 2. Eliminate straightening stress c) Blank after quenched and tempered bending straightening, the eliminating stress temperature should be lower than 30 - tempering tempering temperature 50℃。 d) Its elimination after quenching parts straightening temperature to reduce the hardness for the principle, general is 160 - 300 ℃, in dry or oil bath