For different material samples and different detection distances, different types of proximity switches should be selected so that they have a high performance-to-price ratio in the system. Therefore, the following principles should be followed in the selection:
1 When the detector is metal, a high-frequency oscillatory proximity switch should be used. This type of proximity switch is most sensitive to iron-nickel and A3 steels. For aluminum, brass and stainless steel samples, the detection sensitivity is low.
2 When the detection body is non-metallic material, such as wood, paper, plastic, glass, and water, a capacitive proximity switch should be used.
3 When metal objects and non-metals are to be detected and controlled over long distances, photoelectric proximity switches or ultrasonic proximity switches should be used.
4 When the detection body is metal, if the detection sensitivity is not high, an inexpensive magnetic proximity switch or Hall proximity switch can be selected.
5 proximity switch specification detection
6 Movement distance measurement; When the action piece is close to the sensing surface of the proximity switch, the proximity switch action distance is the maximum operating distance of the proximity switch, and the measured data should be within the product's parameter range.
7 Determination of the release distance; when the action piece moves from the front side away from the sensing surface of the proximity switch and the switch changes from motion to release, the maximum distance from the action surface is measured.
8 Determination of hysteresis H; absolute value of the difference between the maximum movement distance and the release distance.
9 Determination of the operating frequency; using a speed-regulating motor to drive the bakelite disc, fixing a number of steel pieces on the disc, adjusting the distance between the switch sensing surface and the action piece, about 80% of the switching distance, rotating the disc, in turn The action piece is close to the proximity switch. A speed measuring device is installed on the spindle of the disc. The output signal of the switch is shaped and connected to a digital frequency meter. At this time start the motor, and gradually increase the speed, under the conditions of the product of the speed and the action piece and the frequency count equal, the frequency of the switch can be read directly by the frequency meter.
10 Repeat accuracy measurement; The action piece is fixed on the measuring tool, and the motion speed is controlled at 0.1 mm/s from the switch action distance of 120% of the distance, from the front of the switch sensing surface to the action area of the switch. When the switch is activated, read the reading on the gage and then exit the action zone to turn the switch off. Repeat this 10 times, and finally calculate the difference between the maximum and minimum values of 10 measurements and the 10 average values, and the difference is the repeat accuracy error.