Proximity switch selection and detection - Solutions - Huaqiang

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1. Selection of proximity switches For different materials and different detection distances, different types of proximity switches should be used to make them have high performance-price ratio in the system. For this reason, the following should be followed in the selection. in principle:
1.1. When the test object is a metal material, a high-frequency oscillation type proximity switch should be selected. This type of proximity switch is most sensitive to the detection of iron-nickel and A3 steel samples. For aluminum, brass and stainless steel samples, the detection sensitivity is low.
1.2. When the test object is a non-metallic material, such as wood, paper, plastic, glass and water, a capacitive proximity switch should be used.
1.3. For metal body and non-metal to be remotely detected and controlled, photoelectric proximity switches or ultrasonic proximity switches should be used.
1.4. When the test object is metal, if the detection sensitivity is not high, a low-cost magnetic proximity switch or a Hall-type proximity switch may be used.
2. Proximity switch technical indicator detection
2.1. Determination of the action distance; when the action piece is close to the induction surface of the proximity switch, the distance of the proximity switch is close to the maximum action distance of the switch, and the measured data should be within the parameter range of the product.
2.2. Determination of the release distance; when the action piece leaves the sensing surface of the proximity switch from the front, and the switch is turned from the action to the release, the maximum distance of the action piece from the sensing surface is determined.
2.3. Determination of the hysteresis H; the absolute value of the difference between the maximum action distance and the release distance.
2.4. Measuring the action frequency; driving the bakelite disc with a speed-regulating motor, fixing a number of steel sheets on the disc, adjusting the distance between the sensing surface of the switch and the action piece, about 80% of the switching action distance, rotating the disc, in turn The action piece is brought close to the proximity switch, and a speed measuring device is mounted on the spindle of the disk, and the switch output signal is shaped and connected to the digital frequency meter. At this time, the motor is started, and the rotation speed is gradually increased. Under the condition that the product of the rotation speed and the action piece is equal to the frequency count, the frequency of the switch can be directly read by the frequency meter.
2.5. Repeating accuracy measurement; fixing the action piece on the measuring tool, except for 120% of the switching action distance, from the front of the switch sensing surface to the action area of ​​the switch, the moving speed is controlled at 0.1 mm/s. When the switch is actuated, read the reading on the gauge and then exit the action zone to open the switch. This is repeated 10 times, and finally the difference between the maximum value and the minimum value of 10 measurements and the 10 average values ​​is calculated. The difference is the repeat accuracy error.