Torque measurement comes to larger shafts

Edited by the Engineeringtalk editorial team Nov 6, 2006

The Dataflex measuring shaft adds new application ranges for torque measurement.

With the Dataflex measuring shaft, KTR has entered new application ranges for torque measurement.

To date, this measuring method has mainly been suitable for testing machines because the measuring devices have been relatively complicated and consequently quite expensive.

As Dataflex makes use of an innovative measuring method which can be realised at a low cost and as a compact design, torque measurement is now suitable for the application on serial machines - for example in process control, quality control, preventative maintenance or as an efficient overload system.

Following the success of Dataflex with shaft diameters from 22 to 85mm, KTR has now extended the series to include bigger sizes: the new Dataflex types with shaft diameters of 85 and 140mm are suitable for torques up to 10,000 and 50,000Nm, respectively.

The new sizes follow the same measuring methods of the smaller Dataflex types.

Two discs are installed on the measuring shafts which, similar to shaft position encoders, have a large number of specifically designed windows.

When torque rises the slotted discs are twisted relative to one another so that the windows of the two discs cover each other proportionally to the torque.

Using special light transmitters and receivers, the light passing through the discs can be measured.

The transmission ratio of light is proportional to the torque.

One benefit of this measuring method is that it is not necessary to transmit energy or signals from or to rotating parts because all electronics are located in a stationary, very compact housing.

For that reason, the user can do without slip rings or telemetric systems and the measuring dynamics are increased.

The band width of the torque signal is more than 16kHz.

As Dataflex measures the speed as well, two important figures are available for data processing and measuring the power of drive systems.

The torque measuring shaft was designed as a complete unit with integrated electronics providing standard signals as 0-10V and simultaneously 4-20mA.

Consequently, an external measuring amplifier is not necessary because the customer may use standard devices like multimeters, oscilloscopes or standard measuring cards for the evaluation, therefore saving costs.

To integrate the product into the drive system as easily as possible, Dataflex can be supplied as a complete unit along with torsionally rigid steel lamina couplings which avoid shaft misalignments and incorrect measuring results.

The new sizes of Dataflex allow it to be used on other applications in serial machines.

One obvious example is the viscosity control in a mixer or agitator.

A viscometer can be used measuring offline and with a delay, or the torque on a mixer drive can be measured by Dataflex allowing very accurate conclusions to the viscosity of the material being mixed.

The compact torque measurement is also suitable on extruders, screwing machines, worm drives, coilers, mobile machines and general applications in machine control and quality assurance.