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1, Functions of the steel reinforcement
(1) To enhance the rigidity and strength of windows and doors
(2) To prevent the profile¡¯s deformation
(3) To fasten the hardware installed
2, Technical requirements on steel reinforcement
(1) Material specification and surface treatment of steel reinforcement
Generally made of cold-rolled Q235 steel band with surface gone through anticorrosion or galvanization treatment to prevent corrosion, wall thickness¡Ý1.2mm, Generally it could be 1.2mm, 1.5mm, 2.0mm, 2.5mm or 3.0mm. It is recommended to use 1.5mm steel reinforcement at least. The thickness of steel reinforcement is selected by calculating the wind load based on the dimension and location of windows and doors. (Pls refer to appendix 1).
(2) Dimension and shape of steel reinforcement
The steel reinforcement is installed inside steel reinforcement cavity of UPVC profile. The fit clearance between the steel reinforcement and steel reinforcement cavity is 1¡À0.5mm, to guarantee convenient installation of steel reinforcement and restore to former shape after being exposed to wind pressure. The allowance for exterior dimension is between -0.1¡«-0.5mm when machining the steel reinforcement.
The shape of steel reinforcement is designed in accordance the profile¡¯s inner cavity shape and type as well as the requirement on hardware installation and is generally classified into closed rectangle, round, U, semi-closed U, square, etc.
Please refer to appendix 2 for the dimension and shape of steel reinforcement in Yatai profile lineups.
- Appearance of steel reinforcement
- The steel reinforcement should have flat interior and exterior surfaces and be free from cracks, lamination, joint welding defects, etc.
- The slot inclination at two ends of the steel reinforcement should be less than 7¡ã, with a clear-cut exterior shape, clear angle and free from burrs.
3, The principle for installation of steel reinforcement
It is recommended that all steel reinforcement cavities be installed with steel reinforcement. The steel reinforcement must be installed under following circumstances:
- The steel reinforcement must be installed if the strength of frame, sash and mullion could not reach a safe value after the calculation of wind pressure resistance.
- The steel reinforcement must be installed when hardware is fixed on the frame, sash and mullion with self-tapping screw so that the self-tapping screw is fixed against the steel reinforcement¡¯s wall and hardware is sturdily installed.
4, Preparation of the steel reinforcement.
The steel reinforcement is cut by band saw or toothless saw. It is suggested to cut 45¡ã at two ends of the steel reinforcement, with an allowance of ¡À1¡ã. The minimum vertical distance between the steel reinforcement and the profile end is 5-10mm to ensure that the hardware¡¯s connection screw could be fixed on the steel reinforcement, with the hardware¡¯s sturdiness strengthened.
The steel reinforcement must be aligned after cutting to ensure that the ends are free from burrs and each linear meter has its linearity less than 1.5mm. torsion degree less than 1¡ã angle deflection less than ¡À1.5¡ã and internal angle radius less than 1.4t(it is the wall thickness).
5, Assembly of steel reinforcement
There are mainly two methods for assembly of steel reinforcement:
- Insert in advance while not affecting the welding position.
- Insert in the steel reinforcement after joining together at cross or T welding position.
It is recommended to choose self-tapping and self-drilling screw as the fastener between the steel reinforcement and the profile. Round-head screw may be used, but not self-plugging rivet. The fastener used to fix each steel reinforcement should be no less than 3, with a gap¡Ü300mm and distance from the steel reinforcement ¡Ü100mm. The steel reinforcement should not come loose after fixing.
The profile interior should be free from any scratch or deformation after the steel reinforcement is installed into the steel reinforcement cavity and the installation of driver handle and door lock is not affected. When the steel reinforcement does not match the profile in dimension, do not install the steel reinforcement forcibly.
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