Diaphragm pump speed adjusting system and feeding system of sand mill

The invention relates to a diaphragm pump speed adjusting system, which comprises a diaphragm pump, wherein the diaphragm pump comprises an air inlet, an air outlet, a feeding port and a discharging port; the air inlet is connected with an air inlet pipe; the air outlet is connected with an air outlet pipe; and an adjusting mechanism for adjusting the working frequency of the diaphragm pump is arranged on the air inlet pipe and the air outlet pipe. By detecting the working frequency of the diaphragm pump and then adjusting the air inlet volume through a needle valve, the diaphragm pump can obtain a stable air flow pressure to perform feeding of the pump. The invention relates to a feeding system of a sand mill. The system comprises the sand mill and the diaphragm pump speed adjusting system, wherein the discharging port of the diaphragm pump speed adjusting system is communicated with the feeding port of the sand mill, and thus the speed of conveyed materials can be relatively stable,so that the sand mill can