Upright spindle box subassembly capable of bearing heavy load

The utility model provides a stand column spindle box subassembly capable of bearing heavy loads, belongs to the technical field of metal processing, and mainly aims to solve the problems that in the numerical control processing technology of a high-load machine tool body, a machine head spindle inclines forwards due to an additional power head assembly for improving the variety of the processing technology, the geometric accuracy of the machine tool is influenced, and the machining cost is reduced. In order to solve a series of problems that an original spindle box cannot bear overweight load and the like, a vertically-added double-stand-column structure is adopted, a gantry door bridge and a vertically-added structure are integrated, and the overall rigidity of equipment is improved. Three sets of machining combinations and corresponding power are fully and intensively arranged on the spindle box, meanwhile, the back faces of the left stand column and the right stand column are each provided with an adjusti