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发表于 2011-5-21 07:37
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来自： 中国山东烟台
Distortion Character Sketch Heat Straightening Requirement Remarks
Distortion which is concave
(a) Distortion figure
(b) Distortion figure 1） Use long strip type heat lines.
2） Heating line is on the rear of stiffeners
3） Heating line quality: If the distortion is severe, two heating lines are used on the both sides of stiffeners’ rear; If the distortion is very small, single heating line is used on the center of stiffeners’ rear. 1） Recommended heating temperatures shall be followed.
2） To avoid stress build up two heats are recommended.
Wave like distortion (1):
Wave like distortion 1) First: Use long strip type heats on the rear of stiffeners on the both sides of recession.
2） Second: Use long strip type heats or other heating methods between the convex stiffeners. 1) Heating temperature shall not be higher than required.
2) First: Do not heat the convex portion, especially the center.
3) Second: The heat straightening need not wait until the first step is over.
Distortion Character Sketch Heat Straightening Requirement Remarks
(2):
Distortion of the same plate panel
1） First: (position 1) Use long strip type heats on the rear of main stiffener.
2） Second: (position 2) Use long strip type heats, short strip type, or cross type heats. When the distortion cannot be completely removed, heat position 3 (including the spot heating method) until the straightening. completing 1） The distance of heating line in plate panel shall be not less than 50~100mm.
2） Heating temperature:
Temperature of the first step shall be not high; the heat of the second step shall be determined by the condition.
The distortion caused by losing stabilization
(1):
Free end of the plate
(a) Distortion figure
(b) Distortion figure
(c) Distortion figure
1） First: Use long strip type heating on the rear of stiffener adjacent to the distortion.
2） Second: Use strip type or cuneal heating method from the position where distortion didn’t occur to free end, see figure （b）、（c）.
3） Necessary fixture may be used during the heat straightening. 1） If heated on the center of distortion or the end of plate, the effect is very badly.
2） The temperature may increase during the course of heating of the second step.
Distortion Character Sketch Heat Straightening Requirement Remarks
The distortion caused by losing stabilization (2):
The distortion all around the hatch 1） Firstly the distortion of plate and stiffener by the hatch shall be level off.
2） Cuneal heating method shall be used to level off according to the heating process of figure.
3） Hammer shall be used to improve the effect of the heat straightening if necessary.
The same to the distortion caused by losing stabilization (1).
Shrinking butt weld (1):
Flat plate
(a) Distortion figure
(b) Distortion figure
1） Long strip type heat straightening shall be used on both sides of straight weld, see figure（a）.
2） When the weld has longitudinal distortion, use short strip heats, see figure（b）, then method of (1) shall be used.
3） To improve the effect of heat straightening, the hammer with slot shall be placed on the weld.
Distortion Character Sketch Heat Straightening Requirement Remarks
Shrinking butt weld (2): Between stiffeners
1） First: Distortion of position (1) shall be used with long strip heats on the rear.
2） Second: Use long strip heats straightening on position 2, 3 of weld both sides and not less than 50mm from welds.
3） If the distortion is severe, special tools shall be used. 1） The heating
temperature shall not be higher than 590℃ for quenched and tempered steels and 650℃ for all other steels.
2） If the distortion of position 2, 3 can not be straightened, repeat heating.
The fillet distortion of face plate
1) The same method as the concave distortion shall be used.
2) Necessary fixture may be used during the heat straightening.
Distortion Character Sketch Heat Straightening Requirement Remarks
The bend of shaped steel
（1）: Transverse bend 1） First: Short strip heating shall be used on the side of crowning of web.
2） Second: Cuneal type heating shall be used on the side of crowning of faceplate.
3） If the distortion is severe, tools can be used.
4） The heat straightening of face bar shall be done after the web is cooling.
1） The heating temperature of web shall be lower than the one of the face bar to avoid other type distortion.
2） Heating of web shall start from the end of bend, not from center.
3） Heating of face bar shall start from the center of face bar.
The bend of shaped steel
（2）: Longitudin-al bend (a) Face plate concave
1） Figure （a）: the Cuneal type heating shall start from two third web heights to the bottom.
2） Figure（b）: the Cuneal type heating shall start from one half-web height to the top; the heating with wide strip shall follow on the same position of face bar.
3） If the distortion is very serious, tools may be used.
1） The heating temperature may be high.
2） Heating shall start from the part where the bend distortion will be short. |
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