Weighing sensor manufacturers take you to understand the development process
Mechanical scale scales are widely used before load cell based resistance strain gauges have become the preferred method for load cell manufacturers in industrial applications. Mechanical scales measure everything from pills to rail vehicles, and they can be accurately and reliably completed with proper calibration and maintenance. Methods of operation may include using a weight balancing mechanism or detecting a force generated by a mechanical lever. The earliest pre-strain metering sensors included hydraulic and pneumatic designs. In 1843, the British physicist Sir Charles Stonestone designed a bridge circuit that can measure resistance. The Wheatstone bridge circuit is ideal for measuring changes in resistance that occur in strain gages. Although the first adhesive resistance strain gauge was developed in the 1940s, it was not until modern electronics technology began to recognize the technical and economic feasibility of the new technology. However, since then, strain gauges have been proliferating as mechanical scale components and independent load cells.
The operating principle of the load cell:
The design of the load cell can be differentiated according to the type of output signal produced (pneumatic, hydraulic, electric) or according to how they are measured (bending, shearing, compressing, tensioning, etc.).
The hydraulic sensor is a force balancing device that measures the weight as a change in pressure of the internal filling fluid. In a rolling diaphragm hydraulic load cell, the load or force acting on the loading head is transferred to the piston, which in turn compresses the fill fluid confined within the elastomeric diaphragm chamber. As the force increases, the pressure of the hydraulic fluid rises. This pressure can be indicated or transmitted locally for remote indication or control. The output is linear and relatively unaffected by the amount of fill fluid or its temperature. If the load cell is properly installed and calibrated, the accuracy can be in the full scale or better 0.25% range and is acceptable for most process weighing applications. Since the sensor has no electrical components, it is ideal for use in hazardous areas. Typical hydraulic load cell applications include tank, tank and hopper weighing. For maximum accuracy, the weight of the tank should be obtained by locating a load cell at each support point and summing their outputs.
Pneumatic load cells also use the principle of force balance. These devices use multiple damper chambers to provide greater precision than hydraulic devices. In some designs, the first damper chamber acts as a tare chamber. Pneumatic load cells are commonly used to measure relatively small weights in industries where cleaning and safety are of the utmost concern. The advantages of such load cells include their inherent explosion-proof performance and insensitivity to temperature changes. In addition, if the diaphragm ruptures, they do not contain fluids that may contaminate the process. Disadvantages include relatively slow response times and the need to clean, dry, conditioned air or nitrogen.
Strain gauge load cells convert the loads acting on them into electrical signals. The meter itself is bonded to the beam or to the structural member, which deforms when the weight is applied. In most cases, four strain gauges are used for maximum sensitivity and temperature compensation. The two meters are usually in tension and the two are in compression and wired through compensation adjustments. When a weight is applied, the strain changes the resistance of the load in proportion to the load. Other load cells are fading away as strain gage load cells continue to increase their accuracy and reduce their unit cost.
下一条: No Information