Precautions for welding pvc profile
The ambient temperature of the processing workshop shall be above 14°C. If the profile is stored outdoors at low temperature,it shall be cut after being stored at the room temperature of not less than 14°C for 24 hours.
The cut section shall be handled with care, and the cut shall be placed downward. Care shall be taken not to contaminate the cut,and the welding shall be completed within 24 hours.
The profile cut surface shall be flat and clean, and free from oil stain, sweat stain, dust, chips and other impurities.
The electrical and pneumatic parts of the welding equipment shall be in accordance with normal working conditions, and the welding cloth shall be complete and smooth without any residue and dust.
Welding technical parameters
Since the welding process parameters are directly related to the profile formula,profile weldability,profile section and ambient temperature,the profiles produced by different manufacturers have different welding process parameters.The assembly factory shall adjust and test the batch of profiles while taking the welding process parameters recommended by the profile manufacturer as reference until the optimal parameter values are found.The reference welding process parameters for DIMEX profiles are as follows:
Welding temperature: 245-252℃
Melting capacity: 3mm
Cooling time: 30s
Welding time:frame 30s,sash 27s,screen sash 25s
Front pressure: frame 0.35-0.4MPa,sash/screen sash 0.35MPa
Rear pressure: frame 0.3 MPa,sash/screen sash 0.25 MPa
Feeding pressure: 0.25MPa
Welding quality evaluation
Welding clearance only solves the problem of whether the welding size is in place,and the welding process condition is the key to ensure the welding quality.According to the gloss and color of the welding slag,we can judge whether the heating temperature is appropriate.If the welding slag is light yellow in luster, the heating temperature is appropriate. If the welding slag is dark yellow and lusterless, the heating temperature too high .If the welding slag is white and lusterless,the heating temperature is too low.According to the size of the welding slag flanging,we can judge whether the welding pressure is appropriate.If the welding slag flanging is large, it indicates that the welding pressure is too large and the molten part is completely extruded.At this time,the angle strength value is the lowest.If the welding slag flanging is small and uneven, it indicates that the welding pressure is small and the PVC molecules are not fully combined,which indicates that the mechanical property of the profile is low.
The proper welding time can be judged according to the hardness of welding slag flanging.Although the cooling shaping of the profile after welding is not completely completed in the welding and extrusion process,the selection of welding time has a direct relationship with the full cooling shaping of the profile under constant pressure and temperature.Long time is beneficial to the shaping of fillet weld,which can reduce the influence of welding stress on the strength of fillet weld.