1.开裂类型及产生原因1.1在塑料门窗的组装、安装和使用过程中,有时会出现焊角开裂的现象。这种焊角开裂通常有三种表现形式:一种是沿焊缝整齐开裂,并且裂缝会一直扩展至焊角的根部,如图(1)所示,第二种是起始在焊缝处不规则地开裂,当裂缝扩展至焊缝长度的1/3-1/2处时转折向型材断面方向,如图(2)所示;第三种是在距焊缝约3-4mm 处沿型材断面方向开裂,如图(3)所示。焊角开裂的原因和形式既与型材的内在质量有关,如原材料、配方和挤出成型工 1. Cracking types and causes 1.1 plastic doors and windows in the assembly, installation and use of the process, sometimes there will be welding phenomenon of cracking. There are usually three forms of this type of weld cracking: one is to crack neatly along the weld and the crack extends all the way to the root of the weld as shown in (1), and the second is to start at the weld Regularly cracking, when the crack extends to the weld length of 1 / 3-1 / 2 at the cross-section profile direction, as shown in Figure (2); the third is about 3-4mm away from the weld along the profile Section cracking direction, shown in Figure (3). The reason and form of weld cracking is related to both the intrinsic quality of the profile, such as raw materials, formulations and extrusion molders