The weighing sensor is actually a device that transforms a quality signal into a measurable electrical signal. With sensor should first consider the actual work environment, it is very important to correctly choose the weighing sensor, it is related to sensor can work normally and its safety and service life, and even the whole weighing apparatus of the reliability and security. In the basic concept and evaluation method of the main technical indexes of weighing sensor, the new old country is marked with qualitative difference. There are mainly s-type, cantilever type, wheel spoke, plate ring type, membrane box type, bridge type, cylinder type, etc.
1. Sensitive components
Direct feelings are measured (quality) and outputs other components that are measured to determine the relationship. As the elastomer of the resistance strain weighing sensor, the quality of the measured object is transformed into deformation. The elastic body of a capacitive weighing sensor is transformed into a displacement.
2. Transform components
The sensor is also called sensing element, which transforms the output of a sensitive component into a signal that is easy to measure. If the resistance strain gauge (or resistance strain gauge) is used as the resistance strain gauge, the deformation of the elastomer is converted to the change of the resistance quantity. Capacitors of capacitive weighing sensors convert the displacement of elastomers to changes in capacitance. Sometimes certain elements have the function of both sensitive and transforming elements. As the piezoelectric material of the voltage weighing sensor, under the action of the external load, the power output can be output at the same time.
3. Measuring elements
The output of the transform component is transformed into an electrical signal to facilitate further transmission, processing, display, recording, or control. For example, the electric bridge circuit in the resistance strain weighing sensor, the charge preamplifier of the piezoelectric weighing sensor.
4. Auxiliary power supply
Provides energy for the sensor's electrical output. General weighing sensor is required for external chain power supply. Therefore, as a product, it must indicate the requirements of power supply, but not as a component of weighing sensor. Some sensors, such as the magnetic speed sensor, can work properly because of the high energy output. So not all sensors have an auxiliary power supply
Commonly used material
The performance of weighing sensors depends largely on the choice of materials. Weighing sensor materials include the following parts: strain sheet material, elastomer material, adhesive material, sealant material, lead sealing material and lead material.
Strain gauge and resistance element material
Strain gauge is induction part of weighing sensor, it will be the size of the external force into electrical signal output, is the most important part of the sensor, the commonly used strain gauge base material with polymer thin film materials, strain material usually for high purity constantan. The properties of strain gauge are not only related to the purity and copper purity, but also related to manufacturing process. Improving process technology level is also an important aspect of improving sensor performance.
Weighing sensor elastomer is the function of external force, it must be under the same force, deformation, produced because of the strain gauge is pasted on the elastomer, the deformations of the elastomer is strain gauge deformation; At the same time, it must have a reset, which can be automatically reset when external forces disappear. Elastomer materials usually select all kinds of metals, mainly aluminum alloy, stainless steel and alloy steel etc.
Patch adhesive material
The adhesive is to hold the strain and elastomer firmly together, so that the deformation will always be consistent. Therefore, patch adhesive is also an important component. At the beginning of the 21st century, the use of multi-piece adhesive is a two-component polymer epoxy series adhesive. At the beginning of the 21st century, its performance is very much related to its own purity, mixing mode, storage time, curing mode, curing time and so on. Before using it, you should carefully read its detailed introduction.
The early weighing sensor seals were sealed with sealant. Later, due to the development of manufacturing technology, welding technology could improve the stability and service life of the maximum sensor. Although welding technology was used in many parts of the 21st century, some important parts were also covered with sealant. Sealant is commonly used silica gel, silica gel has the advantage of stability, it can be moisture-proof, anti-corrosion, the insulation performance is also very good.
Lead sealing and lead material
The sensor output leads can be damaged or loose if they are not fixed, causing the signal to be unstable or not output. In the 21st century, the sensor output adopts the connector, and the material and fastness of the connector will also affect the output. It is best to use connector and sealant for use. Internal leads also need to be fixed to prevent them from moving around. The quality of the lead is also important. The material properties of the wire are in the order of silver, copper wire and aluminum. If the ambient high frequency signal and radio wave interference are serious, the shielding cable should be adopted. In corrosive environment and flammable and explosive situations, anti-flame retardant and explosion-proof cables should be used, with the protection of casing.