The load cell is one of many load cells. In the traditional concept, the load cell and the load cell are collectively called the load cell, and its measurement parameters are evaluated by a single parameter. The experiment and evaluation methods of the old national standard load cell and load cell are not distinguished, but the two load cells are combined into one. There are a total of 21 indicators in the old national standard, all of which are tested at room temperature, and the old national standard uses the largest error among the six indicators, including hysteresis error, repeatability error, creep, and zero temperature additional error, to determine the weighing The accuracy level of the load cell, these levels are represented by 0.02, 0.03, and 0.05 respectively. What are the precautions for the selection of load cells? What is the market prospect of this kind of load cell? In the next article, the editor will introduce this knowledge in detail for you, I believe it will definitely help you deepen your understanding Understanding of this.
The load cell, to put it simply, uses this device to convert the quality signal into an electrical signal that can be measured and output it. Before using any kind of load cell, you must first consider the working environment of the load cell. Of course, this is also very important for the correct selection of load cells. The quality of the working environment is related to whether the load cell can work normally, its safety and service life, and even the safety and reliability of the entire weighing instrument. In the basic concepts and evaluation methods of the main technical indicators of the load cell, the new national standard is qualitatively different from the old one.
Selection of load cell
TC series
The TC series load cell is a tension measurement load cell, which is often used for static measurement and dynamic measurement, in a compressed form, and has good accuracy. Its mechanical part is composed of a whole piece of metal part, so this basic measuring element and its shell part have no welding process, which makes the size smaller and strengthens the protection level. This kind of point measurement structure has 8 tension measurements to reduce errors caused by imperfect load applications. Typical applications of parallel weighing elements are: storage boxes, feeding hoppers, and large weighing platforms. The stainless steel structure is suitable for applications in aggressive environments in the petrochemical and chemical industries.
Main features:
The measuring range is from 100 to 20.000Kg
Load cell
Accuracy level: 0.2%
All stainless steel structure
Anti-corrosion
Calibration signal formed internally
Protection level: IP67 (DIN40050)
TU series
The TU series load cell is a tension measurement load cell, which is often used for static measurement and dynamic measurement, in a compressed form, and has good accuracy. Each load cell mass (Kg) of all transmitters is calibrated. TU series quasi-loads can be supplied from 50Kg to 1 ton. This model has an IP67 protection level, so it can be used in some dangerous chemical industries. Its mechanical part is composed of a single piece of metal, so there is no welding process. This means that it is highly resistant to mechanical shock and vibration. This compact size means that these units can be placed in difficult-to-access and small spaces.
Main features:
The measuring range is from 50 to 1000Kg
Accuracy level: 0.2%
All stainless steel structure
Anti-corrosion
Protection level: IP67 (DIN40050)
Compressed size
TR series
The TR series (GEFRAN) load cell is used to measure the tension of the tension plastic film or tape that is often used for winding on the mechanical guide roller. It can be installed on the fixed and transmission shaft on the mechanical chassis, and its function on the end shaft is a pressure sensitive element and load function. It can be used on both fixed and rotating shafts. TR series load cells can be supplied with fixed, 4 M6 thread or center thread with M10 or M12 adapter flange.
Main features:
The measuring range is from 100N to 2KN
Accuracy level: 0.5%
Anti-corrosion
Calibration signal formed internally
The minimum sensitivity axis direction is 35 degrees from the fixed hole.
Protection level: IP65 (DIN40050)
Form overload protection
Selection of weighing load cell in weighing system
Many factors should be considered when selecting load cells. In actual use, we mainly consider the following factors. In addition, the sensitivity of the load cell, the maximum number of divisions, and the minimum verification division value are also indicators that must be considered in the selection of the load cell.
(1) Use environment
The load cell is actually an output device that converts the quality signal into a measurable electrical signal. When using a load cell, we must first consider the actual working environment in which the load cell is located. This is essential for the correct selection of the load cell. It is related to whether the load cell can work normally, its safety and service life, and even the reliability and safety of the entire weighing instrument. Under normal circumstances, the high temperature environment will cause problems such as melting of the coating material, opening of the solder joints, and structural changes in the internal stress of the elastomer; dust and humidity will cause short-circuit effects on the load cell; in a highly corrosive environment, it will cause the load cell elastomer Damage or short-circuit phenomenon; electromagnetic field will interfere with load cell output. Under the corresponding environmental factors, we must choose the corresponding load cell to meet the necessary weighing requirements.
(2) The number and range of load cells
The selection of the number of load cells is based on the purpose of the electronic weighing instrument and the number of points that the scale body needs to support (the number of support points should be determined according to the principle that the geometric center of gravity of the scale body and the actual center of gravity coincide). Generally speaking, if the scale body has several supporting points, several load cells are used.
The range of the load cell can be selected according to the maximum weighing value of the scale, the number of selected load cells, the self-weight of the scale, the maximum eccentric load that can be generated and the comprehensive evaluation of the dynamic load factors. Generally speaking, the closer the range of the load cell is to the load assigned to each load cell, the higher the accuracy of its weighing. However, in actual use, in addition to the object being weighed, the load added to the load cell also contains the dead weight, tare weight, eccentric load, and vibration and shock loads. Therefore, when selecting the load cell, many factors must be considered to ensure The safety and longevity of the load cell. An empirical formula verified by a large number of experiments is given below.
The formula is as follows:
C=K0&TImes;K1&TImes;K2&TImes;K3(Wmax+W)/N
Where C is the rated range of a single load cell
W-weight of the scale
Wmax-the maximum value of the net weight of the object being weighed
N-the number of support points used by the scale body
K0-insurance coefficient, generally between 1.2 and 1.3
K1-shock coefficient
K2-the center of gravity offset coefficient of the weighing body
K3-wind pressure coefficient
(3) Application range and purpose of various types of load cells
The choice of the weighing load cell form mainly depends on the weighing type and installation space to ensure proper installation and safe and reliable weighing; on the other hand, the manufacturer’s recommendations must be considered.
For load cell manufacturers, it generally stipulates the force condition, performance index, installation form, structure form, material of the elastic body, etc. of the load cell. For example, aluminum alloy cantilever beam load cells are suitable for electronic price calculation scales, platform scales, case scales, etc.; steel cantilever beam load cells are suitable for electronic belt scales, sorting scales, etc.; steel bridge load cells are suitable for railroad scales, truck scales, etc.; column type The load cell is suitable for truck scales, dynamic railroad scales, large-tonnage hopper scales, etc.
Load cells are mainly used in various electronic weighing instruments, industrial control fields, online control, safety overload alarms, material testing machines and other fields. Such as electronic truck scales, electronic platform scales, electronic forklifts, dynamic axle load scales, electronic hook scales, electronic pricing scales, electronic steel scales, electronic rail scales, hopper scales, batching scales, canning scales, etc.
(4) Selection of the accuracy level of the load cell
The accuracy level of the load cell includes technical indicators such as nonlinearity, creep, repeatability, hysteresis, and sensitivity of the load cell. When selecting a load cell, one should not blindly pursue a high-level load cell, but should consider the accuracy level and cost of the electronic scale. Under normal circumstances, the total accuracy of the selected load cell is the sum of the three indicators of non-linearity, non-repeatability and hysteresis. The root mean square value is slightly higher than the accuracy of the scale.
At present, the global load cell market is showing a trend of rapid growth amid ever-changing innovations. Relevant experts pointed out that the main technology in the load cell field will be extended and improved on the existing basis. Countries will compete to accelerate the development and industrialization of a new generation of load cells, and competition will become increasingly fierce. The development of new technologies will redefine the future load cell market, such as the emergence of new load cells such as wireless load cells, optical fiber load cells, smart load cells, and metal oxide load cells and the expansion of market share.
