A load cell is a method that converts weight signals or pull and pressure signals into measurable
A device that measures electrical signals and outputs them. With sensor technology, information With the continuous development of technology, the load cell has also achieved rapid development. we only have Understand the structural characteristics, working principle and practical application of the load cell problems, so that the load cell can be better used in the field of industrial process control,Promote industrial development.
1 Classification of load cells
According to the conversion method, the load cell can be divided into capacitive type, hydraulic type, resistance strain type
Type and other types, resistance strain type because of high precision, wide measurement range, frequency response characteristics
It has become the most widely used load cell1. Resistance strain type according to the structural form, the load cell can be divided into: spoke type, column type, bridge type, beam type and ring type formula etc. Among them, the spoke load cell (hereinafter referred to as the spoke sensor) is composed of it has strong resistance to lateral force and partial load, low center of gravity, easy installation, simple structure,strong, linear and repeatable, strong overload capacity and other characteristics , are widely used in variousthe field of industrial process control.
2 Structure and working principle of the spoke sensor
The spoke sensor is mainly composed of a wheel rim, a hub and a spoke, and the structure is shown in Figure 1
shown. Among them, the hub is loaded and transmits the load, the hoop is hoop loaded, and the spokes are connected to the wheel.hoop and hub, each spoke is bonded with a resistance strain gauge at the center of both sides, and the spoke
Usually distributed symmetrically in pairs force usually the spoke sensor cooperates with the weighing display instrument (hereinafter referred to as the instrument) when used together, it can directly display the weight of the object. Its working principle is: put the object to be weighed placed on the spoke sensor, the resistance strain gauge on the spoke is deformed and weighed.The sensor converts the weight into a corresponding mV-level electrical signal according to a certain functional relationship,the signal is directly displayed on the display screen after pre-amplification, filtering, A/D conversion, etc.
Display the weight of the object .
3 Auxiliary power supply for spoke sensors
It can be seen from the aforementioned working principle that the spoke sensor needs to convert the weight signal into
It is an electrical signal and output, and an external power supply is required to provide energy when outputting an electrical signal. match when used together with the meter, the energy required to output the electrical signal is provided by the meter. Due to the large number of instruments use 220V AC power supply, and the voltage allows a wide range of changes, so cooperate with the meter 220V power supply can be used directly when in use .Spoke sensors are sometimes used with transmitters, in which case the output sensor.The energy required for the electrical signal is provided by the transmitter. Since the power supply of the transmitter is generally 5V, 12V, 24V, etc., so when used with a transmitter, it cannot be directly connected to 220Vor 380V power supply, need to use switching power supply to convert high voltage to stable low voltageto work properly.
4 Wiring method of spoke sensor ,spoke sensors usually have 2 wiring methods: four-wire and six-wire, by because the four-wire connection method has no special requirements for the instrument and is easy to use, so when the cable is relatively
For a short time, the four-wire system has a high usage rate.when the spoke sensor is used with the transmitter, it needs to use the switching power supply step down, at this time 4 wires lead out from the transmitter cable connector, the colors are red, black,white and green. Among them, the red and black wires are power wires, which are connected to the red and black wires of the switching power supply;The white and green wires are signal wires, which are connected to the host computer to collect output signals.bit machine to monitor and process the output signal.
5 Problems in the application of wheel-spoke sensors
5. 1 Measuring range of the spoke senso
Generally, the closer the sensor range is to the load the sensor bears, the more accurate the weighing will be.
The higher the degree. Because if the weight of the object to be weighed is relatively light (eg 10T), but the
a sensor with a larger range (for example, 50T), the numerical error obtained will be large.In practical applications, it is also necessary to consider the influence of partial load, vibration and shock on the sensor,
Therefore, if the range of the sensor is selected too small, the sensor will be damaged. Therefore choose the
In order to ensure the normal operation of the sensor and prolong the
Its service life . In addition, when the spoke sensor is used with the instrument, due to
The instrument is a general-purpose device (with multiple ranges), using load cells with different load capacities
At the same time, the instrument should also select the appropriate range. If the selection is inappropriate, the staff may
Misjudgments and misoperations are made on the collected data, and in severe cases, the weighing transmission will be damaged.
sensilla.
5. 2 Working environment of the spoke sensor
With the continuous maturity of the spoke sensor technology, its requirements for the working environment
Also more relaxed. However, in the actual application process, we still need to consider the impact of the working environment on
The influence of the sensor, such as dust, wet environment will short-circuit the sensor; high corrosion
The environment of the sensor will damage the elastic body of the sensor or produce a short circuit [4]. So in Paul
On the premise of ensuring the accuracy of the sensor, we must artificially avoid the impact of the harsh working environment on the sensor.
Adverse effects of sensors. For example, in dusty and humid environments, welding can be used
Or other methods to completely close it, and make the upper part into an arc shape, so that it can be evenly stressed
uniform. In addition, when the size permits, it is also possible to consider adding a layer of protection to the outside of the sensor
Cover to reduce the adverse effects of the external environment on the sensor.
6 Epilogue
This paper introduces the structure, working principle and practical application of the spoke sensor.
The problems that should be paid attention to in use can promote everyone's understanding and research on the spoke sensor.
It has certain guidelines for ensuring the safe application and prolonging the life of the spoke sensor
guiding meaning.