Views: 23 Author: Site Editor Publish Time: 2019-06-28 Origin: Site
With the development of technology, industrial products are gradually developing. The tension load cell is also gradually applied in various fields. Next we will mainly introduce what is the tension load cell, the measurement principle and type selection of the tension load cell.
The tension load cell refers to the sensor that collects tension signal. It is an instrument used to measure the tension value of the coil during the tension control process. When the external pressure is applied, the resistance of the strain gauge will also change, and the value of the change will be proportional to the magnitude of the tension applied. The micro-displacement causes displacement of the leaf spring through an external force, and then the tension is detected by the differential transformer. Since the displacement of the leaf spring is extremely small, about +200 μm, it is called micro displacement tension detector.
The tension load cell is placed under the support on both sides of the paper guide roller, and then it is connected to the signal amplifier through the junction box to measure the horizontal tension.
Fr=Tx (cosβ -CoSa )
Fv=Tx (sina -sinβ ) +Fr
The tensile load cell measures the FR to calculate the tension value of the paper web. The tension load cell is made of a special rigid material. The primary and secondary coils of the tension load cell pass correctly through 4 holes of the sensor. The primary coil is an excitation coil and the secondary coil is an induction coil. Normally, the secondary coil has no induced voltage. When the horizontal tension T acts on the load cell, the secondary coil induces a corresponding voltage. The direction of the tension changes and the polarity of the voltage generated by the secondary coil also changes.
In the production line of the paper machine, the paper will expand and shrink at the place where the glue is applied, and tension control is required to eliminate the influence of the glue. At the front drying and glue press section, the glue and post-drying sections, post-drying section and the calender, the web undulation often occurs. Meanwhile, paper breakage occurs and tension control is required.
1) Select the tension load cell reasonably according to the specific measurement purpose, measurement object and measurement environment
①Types
For example, the size of the measure range, the volume requirement of the measured position, the measurement method is contact or non-contact, the signal extraction method, wired or non-wired measurement, domestic or imported, or developed according to special circumstances. After determining which type of tension load cell to use, consider its specific performance specifications.
②Sensitivity
In general, in the linear range of the tension load cell, it is desirable that the higher the sensitivity, the better. Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is beneficial to signal processing.
However, the higher the sensitivity, the external noise not related to the measurement is easily mixed in. It will be amplified by the tension amplifier, which affects the measurement accuracy. Therefore, it requires that the tension load cell itself should have a high signal-to-noise ratio and minimize interference signals introduced from the outside.
At the same time, the sensitivity is directional. When the measured target is a single vector and its directionality is very high, the tension load cell with less direction sensitivity should be selected. Conversely, if the measured target is a multi-dimensional vector, the cross sensitivity tension load cell is required to be smaller.
③Tension Load Cell Response Rate
The tension load cell response rate determines the frequency range of the target to be measured, so it is necessary to maintain undistorted measurement conditions within the allowable frequency range. In general, the response of the tension load cell always has some delay, but if the delay time can be shorter, it will be better.
2) Select the tension load cell according to technical characteristics
①Narrowband tension measurement usually only needs to measure the support force on the side of the tension roller. Even if the support force on both sides of the tension roller is measured, it is only necessary to measure the sum of the support forces on both sides.
②Broadband tension measurement requires using two tension load cells to measure the support forces on both sides of the tension roller, providing the force difference and sum on both sides of the tension roller.
③Thick trip tension measurement generally only allows the strip and the measuring roll to have a small wrap angle, the strip runs almost horizontally, and at this time producing an almost vertical resultant force. The horizontally mounted VBZ series tension load cell is a suitable selection or the vertically installed HBZ series tension load cell is also OK. However, the HBZ series is better than VBZ from the mechanical installation view.
④The 90-wrapped thin trip tension measurement is mostly horizontal/vertical, and HBZ series with 45° tension load cell mounting surface is a suitable selection.
