In modern industrial production, especially in automated production, the first thing to solve is to obtain accurate and reliable information. This requires the use of various sensors to monitor and control various parameters in the production process, so that the equipment works in normal or optimal conditions and the products achieve the best quality. Therefore, it can be said that without a large number of excellent sensors, modern production will lose its foundation. With the advancement of technology, electronic scales made of weighing sensors have been widely used in all walks of life, realizing the rapid and accurate weighing of materials. Especially with the emergence of microprocessors and the continuous improvement of the degree of automation in industrial production processes, weighing sensors have become a necessary device in process control. Resistive strain type weighing sensors are mass-produced by enterprises because of their simple manufacturing process and low processing cost. They have been widely used in the fields of industrial production process detection and control, automatic measurement, etc. in my country.
2 Components of resistive strain type weighing sensors
As a mass-weight conversion element, the resistive strain type weighing sensor is mainly composed of three parts, namely, the resistance strain gauge, the elastic body and the measurement circuit.
2.1 Resistance strain gauge (sensing element)
Resistance strain gauge is also called resistance strain gauge, or strain gauge or strain gauge for short. It is a component composed of sensitive grids and other components for measuring strain. It can convert the change of strain on mechanical components into resistance change. The resistance strain gauge is made of Φ=0.02-0.05mm constantan wire or nickel-chromium wire wound into a grid shape (or corroded into a grid shape with very thin metal foil) and sandwiched between two layers of insulating thin sheets (substrate). Silver-plated copper wire is connected to the strain gauge wire grid as the resistance gauge lead. The measurement principle of the resistance strain gauge: the resistance value of the metal wire is related to the properties of the material as well as the length and cross-sectional area of the me2.2 Elastomer (sensitive element)
The elastomer is a structural part with a special shape. It has two functions. First, it bears the external force of the weighing sensor, generates a reaction force to the external force, and achieves relative static balance; second, it produces a high-quality strain field (area) so that the resistance strain gauge attached to this area can ideally complete the task of converting strain to electrical signals. The metal material used as the elastomer of the weighing sensor will produce micro-strain between tiny grains when it is subjected to external force due to its complex internal organizational structure. After the external force disappears, the micro-strain disappears, but whether it can be completely restored to the original state without force depends on the metal material of the elastomer. If the curve of the loading force and the curve of the unloading force do not coincide, the greater the difference, the greater the hysteresis. The difference mainly comes from the stability and uniformity of the material's own composition, the radial organization after heat treatment, etc. Knowing the cause of hysteresis, we can reduce the hysteresis by selecting suitable metal materials and using advanced heat treatment methods to increase the elastic limit, thereby achieving good comprehensive mechanical properties. The following principles should be observed when designing the sensor elastomer:
(1) The strain zone of the elastic element is subjected to a single force and the stress distribution is uniform;
(2) The support area should be rigidly fixed as much as possible, and the installation force should be far away from the strain zone. If necessary, flexible isolation technology should be adopted;
(3) The design of the loading and bearing pressure head and pressure pad should make the loading line coincide with the center line of the elastic element to ensure that the loading point is stable and unchanged;
(4) The structure and shell design of the elastic element should try to eliminate or reduce the influence of mechanical interference factors (lateral force, bending moment, torque) to minimize performance fluctuations;
(5) If structural conditions permit, overload protection measures should be taken as much as possible. , improve the safety and reliability of work;
(6) The patch area of the elastic element strain zone should be open to facilitate patch operation, and the patch surface should be as flat as possible and easy to install the pressurized curing fixture;
(7) The elastic element is easy to seal at the resistance strain gauge, and the rigidity and welding groove design of the welding diaphragm are reasonable to ensure the sealing quality;
(8) The manufacturing process should be considered while designing the structure, and the design should serve manufacturability;
(9) Reliability should also be considered during structural design, that is, reliability design;
(10) Process design should be conducive to statistical process management of mass production and process flow networking.

tal wire. When the metal wire is pasted on the component, when the component is deformed by force, the length and cross-sectional area of the metal wire also change with the component, and then the resistance changes.

2.2 Elastomer (sensitive element)
The elastomer is a structural part with a special shape. It has two functions. First, it bears the external force of the weighing sensor, generates a reaction force to the external force, and achieves relative static balance; second, it produces a high-quality strain field (area) so that the resistance strain gauge attached to this area can ideally complete the task of converting strain to electrical signals. The metal material used as the elastomer of the weighing sensor will produce micro-strain between tiny grains when it is subjected to external force due to its complex internal organizational structure. After the external force disappears, the micro-strain disappears, but whether it can be completely restored to the original state without force depends on the metal material of the elastomer. If the curve of the loading force and the curve of the unloading force do not coincide, the greater the difference, the greater the hysteresis. The difference mainly comes from the stability and uniformity of the material's own composition, the radial organization after heat treatment, etc. Knowing the cause of hysteresis, we can reduce the hysteresis by selecting suitable metal materials and using advanced heat treatment methods to increase the elastic limit, thereby achieving good comprehensive mechanical properties. The following principles should be observed when designing the sensor elastomer:
(1) The strain zone of the elastic element is subjected to a single force and the stress distribution is uniform;
(2) The support area should be rigidly fixed as much as possible, and the installation force should be far away from the strain zone. If necessary, flexible isolation technology should be adopted;
(3) The design of the loading and bearing pressure head and pressure pad should make the loading line coincide with the center line of the elastic element to ensure that the loading point is stable and unchanged;
(4) The structure and shell design of the elastic element should try to eliminate or reduce the influence of mechanical interference factors (lateral force, bending moment, torque) to minimize performance fluctuations;
(5) If structural conditions permit, overload protection measures should be taken as much as possible. , improve the safety and reliability of work;
(6) The patch area of the elastic element strain zone should be open to facilitate patch operation, and the patch surface should be as flat as possible and easy to install the pressurized curing fixture;
(7) The elastic element is easy to seal at the resistance strain gauge, and the rigidity and welding groove design of the welding diaphragm are reasonable to ensure the sealing quality;
(8) The manufacturing process should be considered while designing the structure, and the design should serve manufacturability;
(9) Reliability should also be considered during structural design, that is, reliability design;
(10) Process design should be conducive to statistical process management of mass production and process flow networking.
2.3 Wheatstone bridge (measurement circuit)
The function of the measurement circuit is to convert the resistance change of the resistance strain gauge into a voltage output. Because the Wheatstone bridge has many advantages, such as suppressing the influence of temperature changes, suppressing lateral force interference, and solving the compensation problem of weighing sensors more conveniently, the Wheatstone bridge has been widely used in weighing sensors.