Mountz PULSE TOOLS Especificaciones descargar pdf (Pagina 27)

Filters

The process of converting pulse type dynamic mechanical torque to an electronic signal using a trans-

ducer may result in unwanted inputs (noise), resulting in a distorted torque value (usually high). Often it

is possible through the use of appropriate circuitry to selectively filter out some or all of the unwanted

noise. Filtering is the process of attenuating unwanted components of a torque measurement (those

which are not torque related, noise) while permitting the desired torque measurement to pass.

In general, if a joint is very hard, i.e., two pieces of steel with no washer, the tool may create sharp

spikes that may create a great deal of electronic noise and “ringing”. Noise and ringing, in this case, are

defined as readings from the transducer that did not result in torque to the fastener (obviously we do

not want to read this on the display). If the joint is very soft (two pieces of plastic with a crush washer)

the tool might create more “rounded” or flat peaks as a result of the energy absorption characteristics of

the soft joint, possibly resulting in much less noise. These two situations may create the need for differ-

ent filters within the tester. A filter acts much like a sieve, it lets certain signals through and stops others.

When you select different filters on the TorqueMate® Plus, you are selecting different “low pass fil-

ters”. This means that the filter will “cut-off” or attenuate any signals above the cut off frequency of the

filter and “let pass” signals below. So a 500Hz filter theoretically will cut out any signal that is entering

that is over 500Hz. If the power tool you are using inputs torque at a rate above 500Hz you might cut

off the peak and get a reading that is too low. When you are using a hand wrench, the rate of applica-

tion is slow, so a 500Hz should work fine. To be safe, you should first try using the 3600Hz filter with

power tools. This will let most of the signal pass through.

If you find that your readings are consistently high, or you get occasional peaks that are high, compared

to the real application torque (see testing of joint) you may be reading noise. Try using the 1500 Hz

filter. No single filter can be specified for every application. This is somewhat of a trial and error

process, however experience has shown that 1500 Hz is the filter selection that should work the the

best for most power tool applications

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Mountz PULSE TOOLS Especificaciones Pagina 27