High Temperature Bell Type Annealing Furnace For Wire

Specifications

Bell type annealing furnaces are mainly used for the bright annealing of steel belts, steel wires, copper belts, copper pipes, it also are widely used for the annealing in standard items, bicycles, chains industries and so on.

1 Electric heating cover (include upper electricity connecting cabinet)

Shell of electric heating cover are completely metal steel structure, welded by Q235 steel and profiled bars, the thickness of shell is 6mm.

Furnace liner inside cover adopts complete fiber structure, furnace body is made of silicate cotton material special shape bricks, high aluminum light bricks are used for wire hanging, upside and coping of furnace liner are built by silicate cotton type fiberboards then fixed by heat resistant stainless steel bolts. Whole furnace liner has very light deadweight, great heat isolation performance and reliable fastness, which can ensure long time use for clients. Temperature rising of outside shell is less than 40°C, which satisfy the standard of national C grade furnace.

Asbestos square coils are used as sealing device for bottom airproof of cover, and are fixed inside tank in the bottom of cover by bolts, which have neat appearance and long time use-life. Leaking hole is made in the top of cover to avoid convergency of hydrogen air and convenient for the vapor discharge during furnace baking.

Cr20Ni80 Nichrome wires are adopted as heating items, coiled in twist shape, then pulled onto porcelain pipes. Porcelain pipes are enchased into slanted flute of wires hanging bricks to avoid ejecting out because of shaking during the lifting up and down of heating cover. Electric control items are collocated in top and bottom two sections, each section is controlled separately, so the power is distributed and collocated very equably and convenient, automatic overturning inlay device is adopted as electricity connecting structure, which is very safety and reliable.

Two direction guiding devices are fixed outside furnace cover, which makes the lifting and dropping down of heating cover become more convenient and accurate.

Temperature testing thermocouples are fixed inside furnace cover and used for the inspection of enacted temperature of heating cover and its over temperature protection.

2 Cooling cover

Cover body is made of Q235 armor plates in 5mm thickness. Two cooling fans with power 1.1KW are fixed on the top, diameter of fan impeller is Ø 500mm, air flow is about 12000m³/hour. Air cooling and water flooding cooling are both adopted, once air cool down the temperature to enacted value, water cooling device on the cover top will start running automatically, when cooling water full fill the top of inner cover, water will flood out through flooding disc and fall down along the inner cover wall, this can improve the cooling efficiency a lot and shorten the annealing period.

3 Inner cover (include direction guiding poles)

Inner cover is made of stainless steel (material 1Cr18Ni9Ti) armor plates in 6mm thickness. Ripple structure is adopted, this not only can enhance the strength of inner cover but also can increase the heating area to improve heat transmission effects. Ripple pitch is 150mm, ripple deep is 10-15mm, envelop head is formed under rotating pressure, its vertical slots and annulus slots are both welded in two sides.

Flange is machined by carbon steel armor plates, after welded onto bottom circle sealing surface is fine machined, special technics is used during group welding to ensure the uprightness tolerance between below surface of flange and center line of cover body is under 10mm against whole length.

Water cooling silicon rubber structure is adopted for the sealing between inner cover and furnace base. Its structure is quite different from traditional sand sealing structure which has improved the sealing performance a lot.

4 Furnace base

Furnace base is made of completely sealing steel structure, which mainly include six parts: circulation fan, wind impeller, furnace base underpan, furnace base body, flow guiding disc and wires loading plate.

Circulation fan adopt 22/5.5KW double speed motor, φ650mm wind impellers, motor shaft and wind impellers are both made of heat resistant steel, rotating speed is 1450/750r/min, Wafangdian brand bearings are used. Dynamic balance test has been down both to motor shaft and wind impeller, related testing reports are also enclosed, imbalance of rotor≤1g, imbalance of wind impeller≤10g, taper of impeller and fan main shaft have both been machined by dies and tested by gauge to ensure interconvertibility. Wind impeller is designed according to spaceflight technology, attested and inspected by authority structure, its air flow and air pressure both have reached the designed requirements. Adoption of big air flow type wind impellers has effectively enhanced the air circulation inside furnace, this not only have ensured the temperature equality inside furnace, but also have reduced the time for heating, heat preservation and cooling a lot, which have highly improved the working efficiency.

Insulation grade of fan motor is H. Fan motor is fixed inside completely sealing water proof jacket, which is protected by water cooling and air cooling at same time to ensure long time no malfunction running.

Furnace base underpan is group welded by 20# flange beams andδ16 armor plates, sealing flange above underpan is made ofδ45 thickness armor plate. Above flange surface there have coattail shape silica gel round piece embed slots, in bottom of flange there have water cooling slots, installation base for circulation fan is fixed in bottom of underpan. After group welding, whole underpan need fine machining to ensure the parallelity between two surface and upstrightness to center line. Adoption of completely turning machining can protect furnace base away from air leaking and water steam vaporing. Wires loading plate is made of Q235 armor plate in 40mm thickness.

Furnace base body is welded by 8mm thickness stainless steel circles and stainless steel diffusion boards. Top surface of diffusion board is made in ellipse sealing head concave for easy flow guidance, stainless steel pipes are used to form supporting frame inside and full filled with heat preservation material to ensure no distortion of furnace base under high temperature and heavy load.

Flow guiding disc is made by 8mm stainless steel pressed into fleet dish shape sealing head, camber shape flow guiding flakes are all welded onto dish shape surface, during which 6pcs bearing flakes are made of 20mm stainless steel plates, rest 12pcs are made of 8mm stainless steel plates; cirque plates is above flow guiding flake, circulation fan impellers are put in the center. Flow guiding disc isn’t welded onto furnace base for easy maintenance of flow guiding disc.

Dynamic balance test has already been down to main shaft of fan and wind impellers, imbalance of impeller≤5g, imbalance of rotor≤1g, which can ensure the dynamic performance of hot flow fan sufficiently.

Temperature controlling thermocouples are fixed on the top of furnace base for automatic temperature control inside furnace.

5 Electric control system

Electric control cabinets are composed of three parts: power cabinet, relay cabinet and meter cabinet. All electric items inside cabinet are adopted from domestic famous brand Delixi to ensure good performance and quality of control cabinets. Temperature control system and PID adjuster adopt high intelligent original Japanese produced temperature controller, which have high temperature control precision. Hangzhou Pangu brand no paer type temperature recorder is adopted for temperature recording and analyzing, which have reliable and stable performance and convenient operation.

Two groups of resistance heating(named as A, B group) are used for heating cover. Two groups of resistance are both working during temperature rising process, but during heat preservation period group A will stop heating, group B will start silence automatic control through controllable silicon power adjusting spring when below zero. Time for heating and heat preservation can both be enacted at any time according to technics requirements of client to ensure automatic control. Conversion of high and low speed for hot flow fan can be adjusted according to technics requirements of client.

Interlock control method is set for control system to avoid mistake operation, sound and light alarm safeguards are also adopted, which can alarm and note for many kinds of malfunctions.