A Brief Introduction of Torsion Load Cell

Torsion load cell is also known as sensor torque, torque meter, divided into two categories: dynamic and static. Among them, the dynamic torsion load cell can also be called torsion load cell, torque speed sensor, non-contact torsion load cell, rotational torsion load cell, etc. torsion load cells detect torque on various rotating or non-rotating mechanical parts. Torsion load cells convert physical changes in torque into electrical signals. Torque transducers are used in the manufacture of viscometers and electric (pneumatic, hydraulic) torque wrenches. It has the advantages of high precision, fast frequency response, good reliability and long life.

Generally speaking, torque is external torque. For example, the rotation of the machine tool spindle is the result of the external torque provided by the power source, and the torque is the internal torque. When the spindle is working, the cutting force of the tool acts on the spindle, resulting in torsional elastic deformation. It measures the magnitude of torque. Torque is the moment that causes a rotational effect or torsional deformation of an object. It is equal to the product of the force and the force arm.

1. Torque in torsion load cell is a parameter often involved in rotating power system

To detect rotational torque, torsion load cells are more commonly used. The torsion load cell is equipped with two sets of gears with the same number of teeth, shapes and installation angles at both ends of the elastic shaft, and a proximity (magnetic or optical) sensor is installed on the outside of the gears. When the elastic shaft rotates, the two sets of sensors can measure two sets of pulse waves. By comparing the phase difference between the leading and trailing edges of the two sets of pulse waves, the amount of torque borne by the elastic shaft can be calculated. The advantages of this method are: the non-contact transmission of the torque signal is realized, and the detection signal is a digital signal; the disadvantage is: the volume is large and the installation is inconvenient. At low speeds, the leading and trailing edges of the pulse wave are slow and difficult to compare, so low-speed performance is not ideal.

2. The more mature detection method for torque testing in torsion load cells is strain electrical measurement technology

Torsion sensor has the advantages of high precision, fast frequency response, good reliability and long life. A special torsion sensor with strain glue is pasted on the measured elastic shaft to form a strain bridge. If the strain bridge is supplied with working power, the torsional electrical signal of the elastic shaft can be tested. This is the basic torsion load cell mode.

However, in a rotating power transmission system, it is a relatively difficult problem to reliably transmit the bridge pressure input of the strain bridge on the rotating body and the detected strain signal output between the rotating part and the stationary part. The usual method is to use conductive slip rings to do it. Since the conductive slip ring is in frictional contact, wear and heat will inevitably occur, which limits the rotational speed of the torsion load cell and the service life of the conductive slip ring. Unreliable contact will cause signal fluctuations, resulting in large measurement errors and even unsuccessful measurements.