No industrial enterprise is complete without a device for measuring the exact weight and tensile force of various parts and metal structures. Strain gauges for weight and pressure convert the amount of deformation into the most suitable signal for measurement. Basically, the signal is electrical. Therefore, manufacturers, having made metal products, check their maximum compression and tension ratio.
Content
- Purpose of the device
- Design features
-
The device in action
- The purpose of the measuring bridge
- Advantages and disadvantages
- Connection diagram
Purpose of the device
Deformation devices are made of strain gages and strain materials, which have the highest sensitivity. The main part of the device is a small diameter aluminum wire. Sometimes sensor manufacturers make foil wires. The principle of operation of all weighing devices is practically the same: in the process of operation, the resistors begin to respond to fluctuations in compression and tension, as a result of which the signal is transmitted to the contacts.
There are sensors for different industries: metallurgical, pharmaceutical and nuclear.
Varieties of strain gauges:
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measuring loads; - movement control models;
- dynamometers - devices for measuring force and weight;
- devices for precise speed fixing;
- strain gauges used for machine tools and automotive engines.
Among all devices, a sensor is most often used to measure weight. There are such types of devices: cantilever, S-shaped, washer and barrel. Beam models are rarely used. The choice of the type of fixture depends on the application.
Design features
Devices are categorized both by form type and by type of construction. To calculate the exact deformation, the strain gauge must have extremely sensitive elements. Their contacts are divided into the following types:
- wire;
- foil;
- film.
The load cell with foil elements is applied by gluing. The system is a 12 µm thick foil strip, but sometimes it is thinner. One section of the tape has a lattice shape, and the second has a dense film. This allows additional contacts to be placed on the material, which makes the system very easy to use. The device is capable of withstanding extremely low temperatures.
Film models are analogous to foil models. The only difference between them is the material for the manufacture. Film sensors are made from a strain-sensitive film, the surface of which has a special coating, which increases the sensitivity of the device. They are used to measure precise dynamic loads. Films are made from germanium, titanium and bismuth.
Wire devices are used to measure loads from 100 grams to tons. Film and foil models are capable of measuring loads over the entire area, while wire gauges only calculate pressure at one point. Single point strain gauges are often used to measure tensile and compressive strain.
The device in action
The basis of the device is a strain gage equipped with contactsattached to the top of the panel. During the measurement process, the contacts come into contact with the object. All strain gauges are based on a single technology for measuring strain through the interaction of sensing elements with a specific part.
The sensor is connected to the mains by means of electrical taps, which are also attached to the sensing plate, after which the contact parts begin to act under constant voltage. The principle of operation of the strain gauge is simple: the measured structure is placed on a special substrate, the weight of which begins to burst. chain and mechanical deformation occurs, and the control contacts convert the resulting tension or compression into electrical signal.
The purpose of the measuring bridge
The load cell is equipped with a measuring bridge to measure the smallest load. Thus, the device is able to calculate any weight and strength. The bridge system is made on the basis of Ohm's law: if the resistance has the same value, then the voltage passing through the resistors will show exactly the same value. That is, 2 factors are involved in the process: external and internal. The first factor affects the body of the object, and the internal one converts the value into a signal.
Household load cells are digital and electronic weight measuring devices. They have contacts that are connected to a metal sheet. When placing objects on the working surface of the balance, contacts begin to act, transmitting the value to the strain gauges, and then to the dial. Devices can be connected to the network or run on batteries.
For example, the Z-SG signal converter analyzes information with high precision. The deviation from the norm of the obtained data is 0.02%. This is a fairly high indicator of accuracy, but there are instruments that show more accurate information. Such strain gauges are equipped with contacts, which are also a transmitter of a converted electronic signal obtained by measuring the force and weight of the part.
Advantages and disadvantages
One drawback is the slight loss of sensor sensitivity during operation at very fluctuating extreme temperatures. It is desirable that the temperature is stable and the humidity does not exceed 30%. Then the device will show more accurate data. Of the advantages, the following can be distinguished:
- the devices have compact dimensions, and this allows them to be operated in any place;
- sensors are capable of measuring dynamic and static voltages, which makes the system convenient to work in different conditions;
- strain gauges can measure the deformation of a part with minimal error.
Devices are simply irreplaceable in all industries. They help to obtain data quickly and with high accuracy.
Connection diagram
It will not be difficult to correctly connect the sensor if you use the circuit. Before buying a fixture you need to decide on the length of the wirebecause it will be difficult to lengthen the cable correctly. Often after that, the accuracy of the data gets lost. This problem can be solved with the se 01 strain gauge controller, which is an amplifier module. It must be built into the device itself.
The scales may contain 2 or more indicators. They must be connected in parallel with junction boxes. If the device is operated from the mains, then it must be grounded. The wires are grounded to a common point using a branching box. After connection, a visual inspection is carried out for the correct connection of the sensor elements. The grounding and all contacts are also checked.
If the inverter is overloaded with work, it may be damaged. In this case it is not recommended to carry out independent repair work. We'll have to carry the device to a specialized workshop.
Among all models, the following are in great demand: DST, NSK K-B-12A, Keli, Utilcell, Zemic, АЦП and НВМ. They differ from each other in technical characteristics, therefore, when buying a sensor, you need to carefully study all the parameters.
