Application of vacuum nitriding the cradle bakelite handle mold

Failure form a cradle of bakelite handle mold
        Bakelite handle is optional cradle 1.smm Q235A thick steel plate 80t punch cold forming. Cradle bakelite handle its mold line with cr12Mov steel, after 970 ℃ quenching, 170 ℃ second tempering (HRC58 a 62, hereinafter referred to as A process) after put into use. Cradle bakelite handle in actual use, each cold 30 times on the need for grinding, the use of 200 times, that is due to the cavity surface nap and failure. This is due to mold wear resistance, anti-seizure caused by poor. To this end, we will go through the mold A Process is then vacuum nitriding treatment, in order to improve the surface properties of the mold, to improve their life.
        2 cradle bakelite handle vacuum nitriding process diagram
        After a cold furnace installed furnace exhaust to 7kPa, then warmed to the desired temperature and soaking nitriding. At this stage into the nitriding, pulsed manner to the furnace charge people a low pressure ammonia per person charge to the furnace interval 4min fresh ammonia, while excluding the loss of activity of the lack of gas, the furnace gas pressure cyclical movements. Vacuum-degree change in the permeability of 7 ~ 53kPa range.
        After infiltration kept at high vacuum in a certain time, so that the diffusion layer up to the depth and the nitrogen concentration of coffee, and then furnace cooling. Using pulse nitriding, the use of physical pressure furnace gas generated by periodically lifting agitation, replace or supplement the mechanical environment mix, nitride effect and uniform layer greatly improved than the original constant voltage method.
        Bakelite handle cradle vacuum nitriding process control parameters are: nitrogen temperature, heat lhJ, furnace gas pressure and for ammonia. In order to find suitable child that mold vacuum nitriding process parameters, the cradle bakelite handle 30kw Pit vacuum furnace orthogonal experiment. Sample size is mm: 20X20X7. Post test range analysis diagram. As can be seen, the larger the nitriding temperature, holding time and furnace gas pressure, and for a small amount of ammonia influence. Abrasion test performed on MM-20-type wear tester.
        Way for the oil-lubricated friction sliding friction; for grinding material GCrl5 (HRC63). Friction conditions: positive pressure 294N; for grinding the sample speed 200r / mi claw to wear width and wear the same size at the time to assess its wear resistance. A Process elapsed time and then the vacuum nitriding wear both samples relationship with the A process based on the wear scar width.
        Visible, which wear resistance than the former. This is because the nitride alloy nitride layer has high hardness, resulting in vacuo nitrided surface has more excellent wear resistance. Sample elapsed time is shorter than the vacuum nitriding processing arts friction coefficient larger sample, and comparing the coefficient of friction increases significantly.
        This means that the vacuum nitriding sample its anti-adhesion properties are improved, namely Hang engaging performance is improved. This is partly due to the formation of the nitride layer to avoid direct contact with the friction coupling member, so reducing the friction coefficient, reducing the frictional heat, delayed seizure phenomenon caused by friction heat; on the other hand is a cradle bakelite handle Thousands nitride alloy nitride layer is highly dispersed state, improve the wear resistance, it is advantageous thousand improve seizure resistance of the workpiece. According to the above test and the test results, the cradle bakelite handle mold by vacuum nitriding production applications.
        40 a / min speed work plant cold 5000 still does not appear surface scuffing than the original without vacuum nitriding each mold cold 200 will lapse of life increased by 25 times, the work process also you do not need to be grinding, so economic efficiency is very obvious.
        (1) Public bowl bang steel vacuum nitriding treatment, wear resistance and seizure resistance were significantly improved, so by the cradle bakelite handle vacuum nitriding treatment of the life of the mold can be greatly improved.
        (2) In order to improve the wear resistance of steel molds CrlZMoV and seizure resistance, a more reasonable vacuum nitriding process parameters: 510 ℃ xsh, furnace pressure 7 a 53kPa, for the amount of ammonia 70L / h.