Spinning forming Technology of Molybdenum Crucible
Molybdenum is a kind of rare metal, which is an important strategic material that canundefinedt be regenerated. Molybdenum is an important base material for the modernization of the country and the construction of modern national defense. As a non-renewable resource, with the increasing application of the material, the demand is increasing, and the price is higher and higher, so the advanced forming method is adopted to deep-process the waste material so as to achieve the purpose of saving material and improving the efficiency. In this paper, the forming technology of crucible is studied. The traditional forming method of the molybdenum crucible is powder metallurgy, machining, riveting, welding and forming, and hot stamping. In the traditional forming method, the mechanical processing crucible wastes material and has low efficiency; the precision of the welding and riveting molybdenum crucible is poor; the stamping molybdenum crucible is shaped and complex, the efficiency is low, the cost is high, and only the simple cylindrical part can be formed. by adopting a spinning forming molybdenum crucible, the utilization rate of the material can be greatly improved, the forming efficiency is high, and the forming of the special-shaped complex shape and the variable wall thickness and the forming of a molybdenum crucible with a flange edge on the mouth part can be realized. The performance analysis of the molybdenum crucible is one of the remarkable characteristics of the group VI element and the high melting point of the periodic table of the periodic table, Its melting point is 2620 ℃, its coefficient of linear expansion (5.8--6.2) is 10 ~, it is only 1/3 ~ 1/2 of general steel, and its thermal conductivity is several times that of many high-temperature alloys. It has a very high elastic modulus, is one of the highest elastic modulus in the industry, is less affected by the temperature, and is still higher than that of the common steel at room temperature even at 800 C. the machine has good extension performance, can be processed into thin foil and very fine wire, and the brittle temperature of the wire is close to the room temperature. The spinning and forming scheme is that the plastic and brittle transition temperature of the crucible is close to the room temperature, so the plastic range of the furnace is extremely poor at room temperature, so the molybdenum crucible is heated and spun, At the same time, the oxidation was started at 300.degree. C., and a thin oxide film was formed on the surface, and the oxide was evaporated at 600-700 C and more than 700 "C. Therefore, the heating temperature of the molybdenum crucible was controlled at about 600.degree. C. And the spinning and forming of the small-wall-thick crucible part can be realized by using the better extending performance. In view of the above analysis, the crucible is formed by heating and spinning, and the temperature is controlled to 600-J:20 & deg; C. The molybdenum crucible part is a small-taper variable-wall-thick thin-wall cylindrical structure, and the mouth part is provided with a conical flanging. Due to the taper of the part, the precision control during the forming of the part is difficult to control, in order to improve the forming precision, a cylindrical part with a wall thickness such as a thick wall and the like is formed by the combination of the prerotation and the strong rotation, the cylindrical part with the wall thickness of the thick wall and the like is firstly formed, and then the cylindrical part with the wall thickness of the deformed wall is forcibly rotated to form a final part. in that proces of the spinning and forming technology of the Wanfang data-base molybdenum crucible, the pure rki. f undefinedq 1-inch n _ _ inch-inch k-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one-one The spinning blank is assisted by local mechanical processing to obtain the molybdenum crucible part.1) Preparation of the flat blank: according to the previous experience, considering the stability requirements of the spinning forming process, it is proposed to adopt the 5-mm thick plate forming. The outer diameter of the plate blank is determined to be m720mm and the wall thickness is 5 mm according to the size of the part according to the principle of volume change. And cutting according to the size by adopting a high-pressure water cutting mode. The outer edge of the flat blank and the surface of the blank are easily scratched to cause the part to be scrapped at the time of spinning, so that the outer edge of the plate blank before spinning needs to be chamfered, and the surface of the blank needs to be ground and smooth. A spin-spinning blank is formed by adopting a spinning process. In the forming process, the feed amount of the rotating wheel per pass is controlled to prevent the blank from being unstable and wrinkling. when the temperature is more than 700 DEG C, the surface of the material is rapidly oxidized, the surface micro-crack is rapidly expanded, the spinning performance of the material is rapidly deteriorated, and the blank is easy to crack and scrap, The final spinning process temperature is controlled at 600-J:20 & deg; C. The first sub-spinning parameter is 151.000 square data and the 14th National Conference of the Technical Exchange of Spinning Technology (3) heat treatment: the destress annealing treatment is carried out on a rotary blank to reduce the material strength of a rotary blank, improve the plasticity of the material, eliminate the deformation stress of the blank material, and improve the spinning performance of the material. The annealing specification is 700 DEG C, the heat preservation is 1 hour, and the air cooling is carried out.4) the second secondary spinning process is designed to manufacture a second rotary die, The wall thickness of the control blank is 0.24--0.34mm larger than the corresponding position of the final part, and the height is shorter than the final part height by about 10 mm. heat treatment of the second secondary spinning parameter 5): carrying out stress annealing treatment on a two-rotating blank, and the purpose of heat treatment and the specification are the same as that of a rotary blank heat treatment; and 6) the third time spinning: spinning and forming a three-spinning blank by a spinning forming process, The wall thickness of the blank is about 0.1mm thicker than the corresponding position of the final part, the height of the blank is consistent with the height of the final part, the size of the profile of the inner cavity is consistent with the final part, and the inner dimension of the blank is ensured by the die. the third time spinning parameter 7) is machined, the three-rotation blank is machined, the bottom of the processing blank is processed to the wall thickness to meet the requirements of the part drawing, the flanging part of the corresponding part is processed and cut to the residual edge, and the inner and outer surfaces of the part barrel section are polished, the final part is ensured to meet the requirements of the drawing, the forming difficulty and the result analysis 4.1 are important during the forming process of the crucible in the induction heating mode, the traditional blank heating mode in the current spinning process generally adopts flame heating, and the heating mode pollutes the environment, It is necessary for many people to operate and the working conditions are bad and the temperature control is difficult. When the crucible is spinning and formed, we try to use the induction heating mode for heating. The concrete implementation process is as follows: we design the intermediate frequency induction heating system. The total power of the device is 200KW, and the heating temperature can reach 1200 DEG C. An inductor with an intermediate frequency alternating current is input, an alternating magnetic field is generated to generate an induced current of the same frequency in the close workpiece, the current is strong on the surface of the workpiece, the surface of the workpiece can be rapidly heated by using the skin effect effect, and the surface temperature can be raised to 600-800 DEG C in a few seconds. The induction heating depth of the general high-frequency (above 10-10 Hz) is 0.5-2.5 mm, the heating depth of the intermediate frequency (1-10KHZ) is 2-10mm, the induction heating depth of the power frequency (50Hz) is 10-20mm, and the intermediate-frequency induction heating system is selected for the thickness of the commonly used plate for spinning and forming. in the forming process, the plate blank is pre-heated by an induction heating mode, the temperature of the slab can be raised to 600 C within 1 minute (for example, the flame is heated to a temperature of 8 minutes or more), And then the heating flame gun is used for carrying out heat preservation and heating to finish the final spinning. the heating temperature is monitored in real time during the heating process, the heating temperature is ensured to be in the forming requirement temperature range, the introduction of the induction pre-heating greatly improves the working environment of the workers, In the process of forming, the precision control problem of the parts is improved. The control of the precision of the parts is mainly solved in the forming. The rotating wheel with the radiuses of R6, R12 and R20 is used to carry out the test in the early stage of the control precision of the radius of the fillet of the rotating wheel. The process test shows that when the R6 spinning wheel is used for forming, The blank is easy to crack and crack and the like, and the surface roughness of the part is not good; when the rotating wheel of the R12 is used for forming, the surface roughness of the part is better, the feeding ratio and the like are adjusted reasonably, and the part sticking die can be made; and the surface roughness of the part is good when the rotating wheel of the R20 is used for forming. The part is not easy to die, and the size precision of the part is poor. The influence of the radius on the spinning precision on the spinning precision can be adjusted by adjusting the control precision of the feed ratio. If the process parameter is not reasonable, the part and the die have a large gap after spinning, resulting in a super-difference of the diameter of the part. in the spinning process, the influence of the rotating speed of the main shaft on the forming performance is small, the rotation speed of the main shaft is set to be 200r/ min, the influence of the feed ratio on the forming precision is analyzed by changing the feeding speed of the rotating wheel, and the test result shows that, The feeding ratio is improved, the part sticking condition can be improved, and the inner diameter precision of the part can be improved. the spinning feed ratio can be selected to be 1.0mm/ r, the influence of the feed ratio on the spinning precision is adjusted by the process parameters, through the optimization and adjustment of the process parameters, the spinning and forming can be fully realized, the precision of the formed part completely meets the requirements of the design standard of the crucible, and 2) the adoption of the induction heating system not only improves the forming efficiency of the parts, but also improves the working environment of the workers, In ord to provide a brand-new method for spinning real-time heating mode, that spinning and forming of the crucible crucible is a preferable scheme for low-cost manufacture of the precious material, so that the cost can be improved, and the market competitiveness of the enterprise can be fully improved.
