Why is the groove milled in the machining center shaped like a Chinese character?

The groove milled by the machining center is splayed inside, which is labor-saving. It turns out that the processing of the splayed oil tank is more complicated, and the technical requirements for workers are higher. Machining the splayed oil tank by numerical control operation does not require professional technology. Only ordinary people who can load and unload workpieces can operate it, and one person can operate 2-6 sets, which saves the cost of using two more workers every year. A year is equivalent to earning a CNC eight-character oil tank machine tool.