Definition
A torque meter, also known as a torque meter or torque meter, is a precision instrument used to measure and record rotational moments. Moment is the effect of the force that causes an object to rotate around its axis, and its unit is Newton, meter or pound-force inch, etc. In industrial production and scientific research experiments, torque meters are key equipment for evaluating the quality of fastener assembly, detecting the performance of rotating components, and analyzing the mechanical properties of materials.
Principle
The core working principle of the torque meter is based on the balance of moments in mechanics and physical sensing technology. When an instrument applies or is subjected to a torsional force, the sensitive elements inside it produce corresponding deformation or signal changes. At present, the mainstream technologies are mainly divided into two categories: strain gauge and phase difference.
The strain gauge forms the Wheatstone bridge by attaching a resistive strain gauge to the elastic shaft. When the shaft is subjected to torsion, the resistance value of the strain gauge changes, resulting in the output of a voltage signal proportional to the torque. The relationship can be expressed as:M = k · ΔU, among themMfor torque,kis the instrument coefficient,ΔUis the output voltage change.
The phase difference torque meter is equipped with signal gears and magnetic sensors at both ends of the drive shaft. When the shaft is torsionally deformed by torque, the pulse signal output by the sensors at both ends will produce a phase difference. By measuring this phase difference, the torque value can be calculated using the formula:M = K · Δφ, among themKFor the torsional stiffness coefficient,ΔφThis is the difference in phase.
Measurement method
According to whether the torque produces effective work during the measurement process, the measurement method can be divided into static measurement and dynamic measurement. Static torque measurement is suitable for low-speed or stationary conditions such as fastening and opening, and the instrument directly displays the peak torque. Dynamic torque measurement is used for real-time torque and speed monitoring of rotating machinery such as motors and engines, and can simultaneously obtain power data. In actual operation, calibration and testing are carried out according to the connection method (such as direct connection of couplings or sensors in series into the transmission chain) and measurement targets, and in accordance with relevant standards (such as ISO 6789, ASME B107 series) to ensure the accuracy and reliability of the measurement chain.
Influencing factors
The accuracy and repeatability of measurement results are affected by a variety of factors. Changes in ambient temperature can cause sensor zero drift and sensitivity changes. The loading rate needs to be stable during measurement, and too fast a loading speed may cause high readings due to inertia. The mounting alignment of the instrument is critical, and non-alignment connections create additional bending moments that introduce measurement errors. In addition, the surface condition of the object being measured, the lubrication conditions, and the way the operator applies force (e.g. the direction of force applied off-axis) also play a role in the measured values. Regular measurement and calibration according to national or international standards is necessary to maintain the long-term stability of the instrument.
Applications
Torque meters have a wide range of applications. In the automotive industry, it is used for engine assembly, tire nut fastening, and component quality inspection. In the electronics industry, it is used to evaluate the assembly torque of microscrews, knobs and hinges. In materials research, it is used to test the torsional strength and shear modulus of composites, wires or polymers. In the packaging industry, it is used to control the tightening and opening moments of bottle caps. In the aerospace sector, it is used for precise tightening control and verification of critical fasteners. These applications rely on quantitative data provided by torque meters for process control and quality assurance.
Selection considerations
Selecting a suitable torque meter is a systematic project, which requires comprehensive consideration of technical parameters and usage conditions. First of all, it is necessary to clarify the measurement type (static or dynamic) and torque range, and the range of the selected instrument should cover the daily measurement range with appropriate margins. The accuracy level needs to meet specific process or standard requirements. Secondly, consider the interface and output signal type, such as analog voltage, current, or digital interface, to ensure compatibility with existing data acquisition systems. If there is oil, dust or electromagnetic interference in the use environment, it is necessary to choose products with corresponding protection levels and anti-interference capabilities. Finally, the ergonomics of the operation, data storage capabilities, and the convenience of subsequent calibration services should also be evaluated. Through systematic evaluation, it is possible to select an instrument that matches the measurement needs.