Sanding machine with function of quickly replacing bottom plate

The invention discloses a sanding machine with a bottom plate quick-changing function, and belongs to the field of electric tools. According to the sanding machine, the bottom plate and the machine body are detachably connected together from the bottom of the bottom plate through the bottom plate locking knob, the bottom plate locking knob can be operated more conveniently through the knob structure, operation is convenient and smooth, the output shaft is locked through the main shaft locking mechanism in a matched mode, it can be guaranteed that the bottom plate is firmly and reliably hung in the axial direction, and the working efficiency is improved. The multifunctional sander has the advantages of being simple in bottom plate dismounting and mounting structure, convenient to operate, firm in mounting and the like, the sander body can be matched with bottom plates of different forms for use, and an all-in-one multifunctional sander is formed. In addition, the main shaft locking mechanism and a starting swi