Displacement measurement is one of the most basic measurement work. According to whether the sensor touches the workpiece, the displacement sensor can be divided into capacitive grating sensor non-contact sensor. The non-contact sensor ensures high pixel, has dynamic response time, low lag deviation even zero.

Non contact sensor, sometimes called proximity sensor, was first used as limit switch, that is, when the tested object is close to a certain distance the sensitive camera, the power switch data signal can be obtained. At this stage, the development trend of proximity sensor at this stage has only been able to detect whether there are blocks, but also to obtain the object block spacing is more sensitive The distance between cameras can be sensed, the information about the appearance design of products interior space parts can be shown, because it can be used to measure the offset of moving animal blocks This kind of sensor is also called non-contact displacement sensor. The common displacement sensors of sheet metal cutter include eddy current loss telescopic displacement sensor, eddy current displacement sensor, capacitance sensor, inductive displacement sensor, etc.

According to the basic principles of various inductors, capacitive sensors are highly sensitive have the following characteristics:

1. Simple structure, strong adaptability, easy to manufacture, easy to ensure high precision. It can be made into small size inductor to complete unique measurement. It can bear high working pressure, high impact load in extreme natural environment such as high low temperature test, strong radiation source magnetic field.

2. The dynamic response is good, because the electrostatic attraction between the electrodes is small, the necessary effective kinetic energy is very small, part of its movement can be too thin, so its resonance frequency is very high, the dynamic response speed is short, it can work at a frequency of several MHz, which is very suitable for dynamic measurement.

3. The large relative variation is only limited by the linear area, the value can be 100% more, which can ensure the screen resolution detection range of the sensor.

4. The temperature coefficient is small because the capacitor value of the capacitance sensor is irrelevant to the metal electrode, the raw materials with low temperature coefficient can be selected to ensure good reliability under the condition of stable external temperature

In general, it can be seen that this advantage is very suitable for laser cutting processing. For laser cutting head, it is more suitable to use capacitance sensor to move sensor.

Structural characteristics of capacitance sensor

The laser generator is composed of an offset capacitance sensor a nozzle body. The inductor is composed of two conical shells of different metal materials inside outside. In the middle of the inner shell layer is porcelain insulation material. The shell layer selects the grounding device is connected with the inner insulation layer. When the inductor is working, the inductor has the shielding effect. The lower edge of the inner shell on one side of the cone type is connected with a circular copper strip the surface insulation layer The ring copper plate is composed of two electrodes of a capacitance sensor on the metal product workpiece. A safety channel is introduced the inner shell to connect with each other in the data signal acquisition system. According to the safety channel, the inner layer of metal material can make the sending electrode piece (ring copper sheet) inductive electrification, all cameras are connected with laser processing machine The particle beam is set up according to the inner metal shell. In the whole process of fiber laser cutting, the gap transformation between the nozzle the workpiece has great harm to the laser cutting quality. If the distance is very small, the great recoil force working pressure will work on the lens, causing the lens to be collided adhered by slag particles, resulting in lens damage. In addition, the nozzle top is easy to suffer slag corrosion It will damage the concentricity of nozzle hole destroy the uniformity of laser cutting direction. If the working gap is too small, the cyclone will reach the surging subsonic flow. The gap between the nozzles is very easy to cause shock wave, the interval will change to the bell