Sure Torque ST-LAB - Electronic Assembly; Transducer; Programmable Logic Controller; Operational Sequence of the Test Cycle Functions

rev. 08.15.2006.
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1.1.3. Electronic Assembly
A basic knowledge of the Electronic Assembly and related components will aid greatly in the understanding of the
function of your ST-LAB Torque Tester.
The main electronic components of the ST-LAB are as follows:
1. The Transducer and the signal conditioning/PLC interface circuit.
2. The PLC.
1.1.3.1. Transducer
The force applied to the Chuck by the Test Cylinder (the application or removal torque), is measured by an
electronic Strain Gauge Transducer. A strain gauge operates by measuring minute changes in a solid-state electrical
conductor as it is flexed or strained. The changes show up as measurable increases or decreases in electrical
resistance to a current flow through the conductor caused by the variation in the cross-section of the conductor.
The Transducer in the ST-LAB is designed to compensate for temperature, vibration and other possible causes of
resistance variation, and to convert the change in electrical resistance into a linear electrical signal, which is
proportional to the force applied to the closure device. In this way, the mechanical force (torque) applied to the
closure device is converted into an electrical signal. This signal is then sent to the PLC, which monitors the torque,
and controls the operating functions of the ST-LAB Sure Torque system.
1.1.3.2. Programmable Logic Controller
The PLC monitors the torque signal and records the peak signal as the actual application or removal torque. This
signal is displayed on the digital display on the screen of the PLC, and can also be output to a variety of data
collection/analization devices.
The PLC also controls the operating cycle of the Sure Torque system. Additionally, the PLC can display
diagnostic and error messages and allows the operator to program various parameters of the test cycle to achieve
optimum performance and accuracy.
1.2. Operational Sequence of the Test Cycle Functions
The basic operational sequence of your ST-LAB Sure Torque system is as follows:
1.2.1. Clamping Sequence
In the first step of the Sure Torque’s operational cycle, the Clamp air cylinder is activated and closes the Clamps
around the neck of the container being tested. Since each set of Clamps has been made to fit a particular container,
the container is firmly held in place, preventing it from bending, twisting or slightly rotating, thus affecting the closure
test results.
1.2.2. Head Lowering Sequence
The second step in the operational cycle is to pneumatically lower the head on which the chuck has been placed.
The head lowers to a height at which the container closure is securely inserted into the Chuck mechanism.
1.2.3. Chuck Actuation Sequence
In the third step in the operational cycle, the Collet closes around the closure being tested, and securely “grasps”
the closure prior to the Chuck rotating it either on, or off the container.
1.2.4. Torque-Test Sequence
In the fourth and final step of the operational cycle, The Test Cylinder is activated, and the torque applied to the
closure being tested is linearly/adaptively increased. The peak torque applied to the closure is measured by the
Transducer. The measurement is displayed on the digital display of the PLC and is available for other optional
functions, (eg: data collection and reporting, statistical analysis, graphic printout, automated capper torque control,
etc.).
The factory default operational test mode of the ST-LAB is the release mode, but it may be programmed to some
of the other available operational mode screens as well in the Miscellaneous Setup screen.