Vacuum nitriding in the cradle bakelite handle mold

Failure in the form of a cradle of bakelite handle mold
        The cradle is optional 1.smm bakelite handle thick steel plate Q235A 80t punch in cold forming. Bakelite handle its cradle mold lines with cr12Mov steel, quenched by 970 ℃ , 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 roughening and failure. This is due to mold wear resistance due to poor occlusion . To this end, we will go through the re- mold Process A vacuum nitriding treatment to improve the surface properties of the mold , to improve their life.
        2 cradle bakelite handle vacuum nitriding process diagram
        After loading the furnace , the furnace exhaust gas to the cold 7kPa, then warmed to the desired temperature and soaking nitride . At this point into the nitriding period to pulse mode to the low-pressure ammonia gas furnace charging people , that every person charged into the furnace space 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 the 7 ~ 53kPa range.
        After incubation at a higher permeability in a vacuum of a predetermined time , to make the depth of the diffusion layer and the nitrogen concentration of the coffee , and then furnace cooled . Using the pulsed nitriding, the use of physical pressure furnace gas generated by periodically lifting agitation , replace or supplement the mechanical environment mix , nitride diffusion layer effects and greatly improved uniformity constant than the original method .
        Bakelite handle cradle vacuum nitriding process control parameters are : nitrogen temperature, insulation lhJ, furnace gas supply pressure and the amount of ammonia . To find the appropriate sub- mold vacuum nitriding process parameters , the cradle bakelite handle 30kw pit in a vacuum furnace for the orthogonal experiment . Sample size mm: 20X20X7. Post test range analysis chart. As can be seen , the larger the nitriding temperature , holding time and pressure of the furnace gas , but has little effect for the amount of ammonia . MM wear test carried out on a 20-type wear testing machine .
        Way for the oil lubricated friction sliding friction ; material for grinding GCrl5 (HRC63). Friction conditions: positive pressure 294N; grinding the sample to speed 200r/mi claw to wear the same size as the width of the wear scar next time to assess its wear resistance. After A Process for the wear and tear of time and then the vacuum nitriding relationship between the two samples A process based on the wear scar width.
        Visible wear latter than the former. This is because the nitride alloy nitride layer has high hardness , resulting in the surface of the vacuum nitriding has optimum wear resistance. Specimen through the vacuum nitriding time is shorter than the coefficient of friction of the sample processing arts greater than the coefficient of friction increases significantly .
        This means that the vacuum nitriding sample of anti -sticking property is improved , i.e. Hang engaging performance is improved. This is because the nitride layer is formed to avoid direct contact of the friction coupling member, and therefore reduces the coefficient of friction , reducing the frictional heat , because the phenomenon of delayed occlusion caused by frictional heat ; cradle bakelite handle by hand thousands nitride alloy nitride layer was highly dispersed state , improved wear resistance , enabling it to improve seizure resistance thousand artifacts . According to the above tests and test results, the cradle bakelite handle mold by vacuum nitriding production applications.
        40 a / min speed work plant cold surface roughening and 5000 have not yet seen the phenomenon than the original mold without the cold vacuum nitriding 200 each lapse of life , increased by 25 times , the work process also without its grinding , so the economic benefits are clear.
        ( 1 ) Male 1 bowl bang steel vacuum nitriding treatment, wear resistance and seizure resistance were significantly improved, so was the cradle bakelite handle molding vacuum nitriding treatment of life 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.