Process Control and characteristics of TCL data cable production (1)

The TCL data cable adopts a two-step process in the production process. The following describes the relationship between process control and performance parameters and these control parameters:
I. Online Detection and quality control during TCL Data Cable Production
To ensure the high quality performance of data cables, the first three processes, Series cables, twisted pairs, and cables, are the most important in the production process. In these three processes, the production of Concatenated cables is heavy.
A. Monitoring of Copper Conductor diameter variation
The change of the diameter of the copper conductor has an important impact on the insulation core. A 0.510/910mm insulated core line of the water capacitor is about 0.001 pF/m, such as copper wire diameter change 0.72mm, and the Insulation Outer diameter unchanged, capacitance about change pF/m. The diameter of the copper wire is increased to 0.002mm, and the capacitance is increased to 3 pF/m. Therefore, the deviation of copper wire diameter should be strictly controlled.
B. Feedback Control of Insulation Outer diameter
In order to ensure constant Insulation Outer diameter, the diameter of each point in the circumference must be scanned by X-Y dual-axis laser diameter measuring instrument or laser diameter measuring instrument. After data processing, the output outer diameter is fed back. In the above structure specification, when the diameter of the copper wire remains unchanged, and the Insulation Outer diameter changes by 002mm, the capacitance changes by about 0.8 pF/m, so the outer diameter of the tolerances is at + 0.005, the capacitance variation can reach 4 PF/m. Through feedback of diameter test, high-precision series lines such as Rosen Tai can be controlled within 003mm MPa when the extruder and line speed synchronization system are good, that is, the Capacitance change will not exceed 2 pF/m.
C. Centralized Monitoring
The concentricity of the extrusion line depends largely on the uniformity of the circumference of the head and the concentricity of the mold. The concentricity deviation of advanced foreign precision molds is greatly lower than 0.001mm, so the concentricity of the extrusion wire core can be more than 95%. The concentricity of the squeeze Wire Core is affected due to the wear of the mold or unexpected situations in the production process, such as line deviation or small Impurity Inclusion. Therefore, the eccentric Display Instrument is installed on the advanced series online, and the insulation thickness around the circumference is scanned by the high-speed rotation of the on-line core surface of the electric sensor probe, so that the eccentric degree can be displayed on the display screen. The repeatability of this online detector can reach + 0.002. When the eccentric value exceeds the set limit, an alarm is automatically triggered, so that the operator can change the mold or rectify the fault in time.
D. capacitor Control
In the production of solid insulation wire core, the dielectric constant of insulation material changes very slightly, so the control of copper wire diameter and Insulation Outer diameter can achieve the purpose of controlling the capacitor. In foam insulation, the control diameter and capacitance must be combined in order to meet the design requirements for both the capacitance and outer diameter of foam insulation. In recent years, due to the continuous improvement of physical foaming technology, foam stability, capacitance and outer diameter are relatively easy. From the perspective of the latest research results, only controlling the outer diameter does not fully reflect the overall quality of the extrusion wire core. Due to process fluctuations and material defects, the surface is often uneven in the production area. In the measurement and control of the outer diameter, especially in the single axis or double axis X-Y), these accidental phenomena may not be measured. In addition, the control is based on the average measured value after processing. However, in capacitor monitoring, whether it is the change of copper wire diameter, the change of Insulation Outer diameter, surface defects or even eccentric, will eventually be reflected on the capacitor. Therefore, capacitor monitoring is the key. To ensure the quality of high-performance data cables, the TCL series online uses an online spectrum analyzer to quickly detect and record small changes in the structure of the entire core by measuring the capacitance, and automatically calculates the impact on the structure return loss. The spectrum analysis of such measurement data is reflected on the microcomputer display screen and stored through FFT Fast Fourier transformation. This is very useful for early detection of Wire Core defects to ensure the transmission of the final cable, and this record can be printed for further process analysis and improvement.
E. Integrated Control
Copper wire diameter detection, Insulation Outer diameter x a y measurement and control and Capacitive monitoring is the most basic online control instrument for the manufacture of data cables, coupled with advanced control processors, You can strictly control the entire line. If conditions permit, you can add eccentric display and FFT Spectrum Analysis Instruments, which will be of great help to improve the product level.
F. Twisted Pair and cable Forming Process Control
In the process of twisted pair and cable formation, the uniformity of single line or wire tension is the most important. In addition to the sensitive closed-loop control of tension, tension monitoring is adopted, display the change of tension at any time, which is helpful to ensure the stability of the process. Therefore, the use of human-machine interaction display control screen will help the operator to timely and accurately understand the process parameters and troubleshooting. The twisted pair cable equipment used by TCL Corporation Gao Deng and Qinlin Corporation of Japan has all been equipped with such a man-machine dialog interface, and the tolerances between the twisted pair and the twisted pair can be controlled at + 0.1mm, the cable breaking distance can be controlled at + 5mm.
2. The above is the Control Analysis of various key parameters. The following describes the relationship between the above process control and the electrical performance characteristics of data cables.
A. Attenuation) indicates that the unit of character a is dB.
Attenuation is the loss caused by signal transmission along a certain length of cable, such:

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This value has a direct relationship with the length of the cable and increases with the increase in frequency, mainly representing the ratio of the initial signal strength to the signal strength of the receiver. The smaller the value, the better. The standard strictly specifies the attenuation performance, I .e:
For category 5 and Category 5: α ≤ 1.967 √ f + 0.023f + 0.050/√ fdB)
For Category 6: α ≤ 1.808 √ f + 0.017f + 0.020/√ fdB)
The properties and geometric sizes of conductor and insulating materials are the main factors affecting the attenuation of UTP cables. The proximity effects on other derived data cables, such as FTP and metal, are also an important factor. The jacket has almost no effect. The most ideal insulating material is foamed perf-propylene FEP), but it is not widely used due to its difficulty in production. The standard only specifies the formulas obtained after many simplification at a high frequency. The formula cannot be used to identify its influencing factors. The actual formula calculated based on the production process is as follows:
α = (6.0*10-3 * √ f ε * (k/d + d/2a2)/round (2a-d)/d) + 9.1 * 10-5f √ ε * tg ε
Formula medium: ε -- insulation equivalent dielectric constant data d -- conductor outer diameter mm f -- working frequency Hz k -- attenuation twisting coefficient, 1 a -- center distance between conductors mm tg ε -- tangent of equivalent Dielectric Loss Angle of Insulation Material
From the above, we can clearly see which parameters affect the attenuation. Generally, when companies generate stable data cables, the raw materials used in a single line are similar. The main difference is that the outer diameter of the d conductor ), including its size and positive and negative tolerances in the same outer diameter. From the above production process control, we can see that the outer diameter tolerances of TCL can be controlled at + 0.001mm. For different line pairs, due to different twisting distances, therefore, the attenuation between different line pairs is different, but the high-precision outer diameter control can be used to minimize the attenuation difference between different line pairs. This is why the data cables of some manufacturers have a large attenuation of the line pair, with a small attenuation, and the attenuation of the TCL data cable is similar to that of the four pairs, the reason is that the difference is not big. In addition, we cannot directly see the effect of temperature on Attenuation in the formula. Currently, the standard and empirical values indicate that the attenuation of temperature increases by 0.4% for each increase of 1 degree.
B. Characteristic Impedance) indicates the character Z unit.
Characteristic Impedance is one of the most important indicators of data cables. Its calculation formula can be listed as follows:
Z = 120 (hour (2a-d)/d)/√ ε
It can be seen from the above formula that the material and geometric size of the conductor and insulation will affect the characteristic impedance value. In combination with the attenuation formula, we can see that in order to both the Characteristic Impedance Value and attenuation value of the data cable meet the requirements, we must find a equilibrium point of geometric sizes a and d, in addition to controlling its geometric dimensions a and d, It is controlling insulation ε and tg ε. This value is currently set in the standard to 100 + 15 Ω or 150 + 15 Ω C. similar to the materials currently used in attenuation, the outer diameter tolerances of copper and the outer diameter tolerances of insulation are mainly used, in the process control, we can see that the tolerances of TCL can be controlled to + 001mm and + 003mm respectively, which is difficult for other manufacturers. Therefore, the impedance of the TCL data cable can be controlled within 100 + 8. The less the impedance fluctuation, the better the control for impedance mismatch during transmission. Therefore, the smaller the value fluctuation, the better. The ideal state is that no fluctuation is 100 Ω or 150 + Ω.
C. Near-End crosstalk Near End Cross talk) indicates the NEXT character unit dB