How many types of the needle valves do you know
The types of needle valves
According to the different types of sensitive components and structures, the types of needle valves can be divided into piston type, membrane type, elastic film type, bellows type, lever type, etc.
The piston needle valve works reliably, with small maintenance, large pressure reduction range, small footprint and wide range of application.
The diaphragm needle valve has poor working reliability, large maintenance volume, small pressure reduction range, large volume and large floor area, and is only used in pipelines with water and air as the medium at low temperature and pressure.
The bellows needle valve has a large adjustment range, and is used for the pipeline of clean media such as air and steam at a working temperature of 200 degrees, and cannot be used for the depressurization of liquids, let alone for pipelines containing solid particle media. The filter is usually installed in front of the pressure reducing valve to ensure that the pressure reducing valve is sensitive and reliable.
Wire drawing phenomenon is a kind of product defect formed by the formation of filaments at the product gate after the mold is opened, and this filament sticks to the product or stays in the mold. Let's take a look at the solution.
1. The thermal resistance adopts a two-stage heating method.
2. Shorten the formation of the valve pin and reduce the influence of the valve on the nozzle material.
3. The valve pin is opened back to the trough to reduce the amount of plastic that is pushed out.
4. Reduce the gate size of the system if the contest allows.
5. Add a cooling device to the gate area of the nozzle to reduce the temperature of the front end of the valve pin.
The drawing phenomenon of the open system is generally more common, because when the plastic part is cooled, it is first cured by the skin around the gate, and if the gate area is not fully solidified (the temperature of the gate area is continuously input), then the plastic in the gate area of the mold is pulled out to form a wire drawing phenomenon.