Exploration on heat treatment process of the hotte

2022-08-23
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Exploration on heat treatment process of steel drum sealing roller

steel drum is a metal packaging container used to store and transport petroleum, chemical, pharmaceutical, powder metallurgy and other products. It is necessary to ensure the quality and safety of its contents, especially dangerous goods. In the production of steel drums, the sealing process should have certain strength, rigidity and good sealing performance, that is, no leakage, no leakage, so the quality of the sealing process directly determines the quality of the steel drums. The sealing quality of the steel barrel is affected by many factors, such as the material of the steel plate, the cutting accuracy, the quality of both ends of the weld, the size of the flange, the ripple, the expansion bar, and the shape and size of the sealing roller. In addition, the heat treatment hardness of the sealing roller is also a key factor affecting the sealing quality. Not long ago, our factory encountered such a thing in the production process that a user urgently needed a batch of thin steel barrels. In a market economy, customer focus and customer requirements are our standards. We will immediately replace the sealing roller of the sealing machine and prepare to organize the production of this batch of barrels. But somehow, every 2-3 steel barrels are sealed, and the sealing edge of the steel barrel will appear uneven and roughened. A total of 6 rollers have been replaced in the workshop, but this problem has not been solved. Finally, the processing workshop reprocessed a roller overnight at the time of long sample tensile test. After installation the next day, the problem was solved immediately. After verification, it was found that the heat treatment quality of the previous batch of sealing rollers was not up to standard, resulting in the quality of steel drum sealing not meeting the process requirements. Later, after talking about this with several friends in the same industry, I learned that many barrel manufacturing enterprises have similar problems. In order to avoid detours in production, I would like to share with you some of my experience from years of heat treatment and machining. If there is something wrong, we will discuss it further. Please give me your valuable comments. In order to ensure the sealing quality of the steel barrel, the sealing roller of the steel barrel must have high hardness and wear resistance. When the material is certain, the choice of heat treatment process of the sealing roller directly determines its hardness, wear resistance, service life and the sealing quality of the steel barrel. Next, let's talk about the processing process of steel drum winding roller. 1、 Selection of material for steel drum sealing roller during the sealing process of steel drum body, top and bottom, the material will produce plastic deformation and bear large pressure and friction, so the sealing roller must have high hardness (reaching hrc58 ~ 62), high wear resistance and certain strength and toughness. In order to meet the requirements of high hardness and wear resistance of the winding roller, generally, enterprises can choose carbon tool steel T10 and alloy tool steel Cr12 according to their actual conditions. 1. Carbon tool steel T10. T10 can obtain high hardness and high wear resistance after heat treatment, with small hardenability, large deformation and cracking tendency after heat treatment, but the price is low and relatively economical. Only box resistance furnace and low-temperature salt bath furnace are required for heat treatment. 2. Alloy tool steel Cr12. It is a ledeburite steel with high hardenability and small quenching deformation. After heat treatment, it can obtain high hardness, high wear resistance, sufficient strength and toughness. In addition to box type resistance furnace and low-temperature salt bath furnace, a high-temperature salt bath furnace is also required for the heat treatment of this material. 2、 Processing process route of steel drum sealing roller forging spheroidization annealing rough machining stress relief high temperature tempering finishing quenching cleaning residue inspection hardness tempering cleaning residue inspection hardness fitter repair fine grinding inspection delivery. 3、 Selection of heat treatment process for steel drum sealing roller 1. Pre heat treatment spheroidizing annealing. Carbides in steel billets are often unevenly distributed, so they should be forged before machining to eliminate the unevenness of carbides. In order to eliminate the forging stress, improve the machinability, and prepare the structure for the final heat treatment, it is necessary to cool down slowly after forging and conduct spheroidizing annealing. The spheroidizing annealing process specification of steel drum sealing roller is shown in Table 1) table 1 spheroidizing annealing process specification of sealing roller roller material heating isothermal cooling hardness temperature (℃) time (hour) temperature (℃) time (hour) T10 760 ~ 780 2 ~ 4 680 ~ 700 3 ~ 5 cooling with the furnace to 500 ℃ air cooling HB 207 Cr12 850 ~ 8702 ~ 4720 ~ 750 4 ~ 6 notes: a. the workpiece can be heated with the furnace during spheroidizing annealing of roller blank processed with T10 material, It can also be put into the furnace after reaching the temperature required by the process. However, the roller blank processed with Cr12 material must be put into the furnace at 250 ℃ in order to prevent deformation and cracking. b. The holding time of spheroidizing annealing is calculated by half of the heating time. The heating time here refers to the interval time from the workpiece entering the furnace to the workpiece surface temperature consistent with the furnace wall temperature (which can be determined by visual inspection). 2. Preparation before quenching (1) check whether there are cracks, bumps, scratches and other defects on the surface of the roller. (2) Calibrate the furnace temperature to ensure that the temperature in the furnace meets the requirements. (3) In order to prevent the surface oxidation and decarburization when the sealing roller is heated, the sealing roller should be boxed and protected when heated in a box furnace; When the salt bath furnace is heated, the salt bath should be deoxidized and dredged regularly. The optional packing protectants for box furnace heating are: A. 100% dry new cast iron filings fell to 17706.64 yuan/ton in August; b. Charcoal; c. 40% dry new cast iron chips +60% dry old cast iron chips; d. Waste paper. 3. Quenching operation (1) quenching preheating in order to eliminate machining stress, shorten the high temperature dwell time of the winding roller, reduce its deformation and cracking tendency after quenching, reduce the oxidation and decarburization of the roller surface, and preheat during quenching heating. Preheating specifications are shown in Table 2, table 2. Preheating process specifications for roll sealing roller material preheating temperature (℃) preheating time box furnace (min/mm effective thickness) salt should always pay attention to the problems found in the use of the experimental machine. Bath furnace (min/mm effective thickness) T10 450 30 ~ 60/Cr12

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