Sturtevant Richmont Programmable Torque Verifier FM II, Руководство пользователя

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quality-conscious assembler. The probability of occurrence rises with any lack of attention, train-
ing, or experience - individually and in combination.
On assemblies with multiple fasteners, the previously-listed failure modes that exist for each fas-
tener are joined by a fourth failure mode:
Failure to torque all fasteners.
This may occur due to an interruption in the process which causes the assembler to
resume torque application starting with the wrong fastener after the interruption.
This increases the process failure mode count to three, with only one possible correct assembly
mode.
The PTV/Switch Wrench system directly addresses all three of these failure modes, reducing the
probability of occurrence and increasing the probability of detection of each. Further, the proba-
bility of detection is immediate, and immediately communicated to the operator.
The first two failure modes - jerking the wrench and pulling past the click - are directly related to
time. The PTV/Switch Wrench System uses this linkage to obtain control of the process,
Diagram 1 shows a chart with three elements. The X-axis is time, and the Y-axis is signal
strength. The principle is that the signal begins when the wrench clicks, and ends when the
operator releases pressure on it and allows it to reset. Signal transmission may be by almost
any means (hardwire, FM radio, laser, sound) as long as it begins at the click and ends when the
pressure is released. The threshold element is present to avoid any problems related to noise in
the signal, again, regardless of means of transmission.
When a clicker-type torque wrench is
used properly on a joint, there is a period
of time in which the wrench is clicked
before release; the click has a proper
duration. If a wrench is “jerked” it is
cycled in a shorter period of time than if
properly used. If the wrench is pulled
past the click, it spends a longer period of
time inside the “click”; the duration of a
proper use is exceeded.
In Diagrams 1 - 5, the vertical axis is time
0 seconds, the start of the wrench “click”.