Auxiliary sample grinding device of metallographic grinding and polishing machine

An auxiliary sample grinding device of a metallographic grinding and polishing machine comprises the grinding and polishing machine, the grinding and polishing machine comprises a grinding disc and a protective cover arranged on the outer side of the grinding disc, a limiting plate is arranged at the top of the protective cover, a plurality of limiting through holes are formed in the limiting plate, samples are arranged in the limiting through holes, and bags containing liquid are arranged at the tops of the samples; according to the utility model, the limiting plate is arranged, so that a sample can be limited in the horizontal direction; a bag filled with liquid is arranged, so that the sample can be limited in the vertical direction; a plurality of limiting holes are formed, so that a plurality of samples can be limited at the same time; the liquid in the bag filled with the liquid has flowability, so that the gravity of the liquid in the bag can be uniformly pressed on the sample; when the sample fixing d