The dispensing machine mainly includes compressed air source, main compressed air pipeline, a pair of compressed air pipelines, dispensing valves and timing controllers. The main compressed air pipeline is successively equipped with pressure regulating valves, pressure gauges and three-way valves, one end is connected with compressed air source, the other end is connected with hoses, and the auxiliary compressed air pipe is connected with compressed air source. The air-conditioning valves and branch pipes are arranged in turn, and are connected with the atmosphere, so that the pressure in the branch pipe is negative.
In addition, the piston dispensing valve is driven by air pressure and precisely controlled by a timing controller, so that the glue is extruded from the needle, and the negative pressure has a backdraft effect on the glue, so that the glue leakage phenomenon of the dispensing valve will not occur.
The leakage of glue from dispensing valves often occurs after the valves are closed. 95% of the cases are due to the use of too small needles.
Too small needle will affect the flow of liquid, leading to back pressure, resulting in glue leakage soon after the valve closes. When the valve is in use, too small needle will also affect the bubble movement, as long as the replacement of larger needle can solve this problem.
The conical oblique needle produces the smallest back pressure and smooth fluid flow.
When the valve of dispensing machine closes, the liquid in the liquid leaks. Since the air in the liquid is first cleared, or the glue which is not easy to generate bubbles, or after centrifugation, the gel is defoaming, it can effectively prevent the dispensing valve from leaking.