There are many factors affecting the stability of force sensor, which can be summarized as follows:

1. Structure of force sensor

The design of the elastic element, shell, diaphragm, upper pressure head and lower pressure pad of the force sensor must ensure that there is no performance fluctuation in the structure after loading, or the performance fluctuation is very small. Therefore, in the design of the force sensor, the stress in the strain zone should be single and uniform as far as possible. The patch part is flat; The structure ensures that it has certain ability to resist eccentric load and lateral load. The installation force is far away from the strain zone, and the displacement of the load supporting point should be avoided during measurement.

2. Metal materials of elastic elements

The metal material of the elastic element plays a key role in the comprehensive performance and long-term stability of the force sensor. Materials with high strength limit and elastic limit, good time and temperature stability of elastic modulus, small elastic hysteresis, and small residual stress from machining and heat treatment should be selected.

3. Machining and heat treatment technology

In the process of mechanical processing, due to the uneven surface deformation, the greater the residual stress is, the greater the residual stress is, and the greater the residual stress is generated by grinding. Reasonable processing technology and appropriate cutting parameters should be formulated. During the heat treatment process of the elastic element of weighing sensor, due to the uneven cooling temperature and the phase transformation of metal materials, the residual stress in the core and surface of different directions is generated. The core is tensile stress, and the surface is compressive stress. The stress in the opposite direction must be generated in the tempering process to offset the residual stress and reduce the influence of the residual stress.

4. Resistance strain gauge and strain binder

The resistance strain gauge of weighing sensor should have good performance, requiring good stability of sensitivity coefficient, small thermal output, small mechanical lag and creep, small deviation of resistance value, good batch quality uniformity, etc. The strain binder should have high bonding strength and high shear strength. The elastic modulus is large and stable; Good electrical insulation performance; Having the same or similar thermal expansion coefficient as the elastic element; Creep and lag are small; The volume of the adhesive layer shrinks when curing.

5. Manufacturing process

The working principle and overall structure of strain gauge force sensor determine that some procedures must be operated manually in the production process, while human factors have a greater impact on the quality of weighing sensor. Therefore, it is necessary to develop scientific, reasonable and repeatable manufacturing processes, and add automated or semi-automated processes controlled by electronic computers to reduce the influence of human factors on product quality.

6. Circuit compensation and adjustment

Strain gauge force sensor belongs to assembly manufacturing, the product is formed after the patch assembly bridge. Due to the inevitable internal defects and the influence of external environmental conditions, some performance indicators of the weighing sensor can not meet the design requirements, so it is necessary to carry out various circuit compensation and adjustment to improve the stability of the weighing sensor itself and the external stability.