Load Cell Working Principle

- May 14, 2018 -


Load Cell Working Principles:


1)What is a load cell?


 The load cell is a conversion device for converting a weight signal or a pressure signal into a power signal.


2)The construction principle of the load cell:


Metal resistor has the property of hindering the flow of the current. The same type of metal wire,generally speaking,the slenderness,the higher resistance value.When the metal resistance wire is stretched by external force, its resistance value will increase or decrease within a certain range. Therefore,attached the metal wire(or film) tightly to the object which is to be measured.When the measured object is stretched by an external force, the metal resistance wire (film) also expands and contracts in proportion, and its resistance value also changes accordingly. The load cell is to stick the metal resistance strain gauge onto metal weighing beam to measure the weighing signal.


3)Load cell working principle:


  • Loading on elastomer causes the deformation of elastomer:load cell working principle 1.JPG

    Notes:Any tiny force will cause direction to change.

          Surface of the elastomer:point A and D--stretching

                             point B and C--compressing


          

                                   

  • Change rules of strain gauge:


    The formula of resistance under same environment:    R=p*L/S

                     Notes:  p is resstivity of  material,L is length of the object,S is cross-sectional area of the object

load cell working principle 2.JPG

                                               strain gauges stretches,length longer,        strain gauges compresses,length shorter, 

                                                        cross-sectional area smaller,                     cross-sectional area larger,

                                                      A,B resistance value larger                       A.B resistance value larger


    Conclusion: when a constant mass object under stable environment,if the length becomes longer,the cross-sectional area will decreases,according to R=p*L/S,the resistance value will increase.On the contrary,the value will decrease.



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