Repair plan for damaged heating element of experimental electric furnace
Ordinary heat treatment resistance furnace non-vacuum furnace heating elements mainly use iron-chromium-aluminum (such as OCr25Al7Mo2) and nickel-chromium alloy (such as Cr20Ni80), and vacuum furnaces mainly use molybdenum heating elements.
(1) When the molybdenum heating element is damaged, replace the partially damaged part of the molybdenum heating belt. Cut off the damaged part, take a piece of molybdenum sheet with the same size as the original, clamp it with 2~3mm thick molybdenum sheet on both sides, drill screw holes, and then tighten it with molybdenum screws.
When the molybdenum sheet is found to be deformed, falling, or lodging during daily inspection, it can be baked with a blowtorch to soften it, and its proper shape and related dimensions can be restored by external force, and then it can be hoisted and fixed with molybdenum wire.
(2) The normal damage of the alloy is mainly due to oxidation, thinning and brittleness, lap short circuit, over-burning or erosion by the medium. Nickel-chromium alloy has a longer service life than iron-chromium-aluminum alloy, the strip shape is longer than the wire shape, and the continuous work is longer than the intermittent work.
Nickel-chromium alloy has good plasticity, easy drawing and winding, and is not easy to embrittle after high temperature heating, so it is convenient for repair and welding. Iron-chromium-aluminum alloy has a large resistance coefficient and a small temperature coefficient of resistance. Compared with nickel-chromium alloy, it can save materials, and has stable power and high heat resistance. It has strong resistance to carburization, sulfur and various The capacity of hydrocarbon gas is only slightly poorer in processing performance, and it is difficult to draw and coil. It is properly adjusted outside the furnace during installation, and the necessary bending and compression should be corrected by gas welding and baking; the coefficient of thermal expansion is large (low temperature strength and creep elongation) grow up), there should be room for installation; the welding time should be shortened as much as possible to shorten the length of the heat-affected zone.
2. Troubleshooting
The heating body will soften, expand, fall, first lodging and lapping, and then fusing (melting) after long-term work. In order to prevent the furnace wire from having a certain strength at high temperature and prevent it from softening, collapsing or sagging, the structure and size of the resistance furnace heating wire produced by our factory are all designed reasonably. If there is a furnace wire that tends to fall during use, first check whether the small hook of the furnace wire is functioning (the furnace hook for erecting the resistance ribbon must be firmly built, pressed, and plugged tightly, and must not be loosened), and it can be baked by gas welding or blowtorch. Wire etc. make it soft, and then restore its original shape and size, and wear a porcelain tube in the furnace wire (the mandrel can be worn in the porcelain tube), etc. If two porcelain tubes are used at the same time, the ends of the porcelain tubes must be close together.
The heating element can be directly welded to repair the general broken end. For the serious collapse, which cannot be straightened, or the local over-burning part is seriously damaged, the method of replacing and repairing a section can be generally adopted. It is not necessary to scrap the whole set because of partial failure. Pay attention to the use of The material, diameter, pitch and length of the repaired resistance wire must meet the original technical requirements, and the newly repaired resistance wire must not have defects such as cracks and corrosion, and must be uniform in density. When using the old resistance wire, the resistance wire should not have obvious uneven thickness, oxidation corrosion, crack deformation and aging and brittleness. The old lead-out rod should not have serious oxidation and corrosion. Customers can contact our factory directly for more questions and solutions.
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