Production of new high temperature resistant wires

- Nov 05, 2019-

Due to the special use environment of high temperature resistant wires, the wires are almost always accelerated aging in the high temperature environment of hundreds of degrees Celsius. Any flaws and spots on the wires will affect the service life of the wires. Therefore, the material selection and process of high temperature resistant wires are made. The manufacturing environment and the degree of cleanliness are very important. The whole manufacturing process of high temperature resistant wires can be divided into several steps: conductor size positioning, high silica glass fiber rewinding, insulation winding, coating liquid impregnation, high temperature baking and sintering. In the trial production process, the wire manufacturing equipment must be adjusted according to the process requirements. If the distance from the ideal process is too large, the manufacturing equipment must be partially modified.


Conductor shaping

The nickel-plated copper wire conductor can be shaped by a drawing die to position the conductor in a specified range. It must be noted during the drawing process that the appropriate drawing liquid should be selected, and the drawing liquid must be cleaned after shaping to avoid residual adverse effects on the wire at high temperatures and to release undesirable gases in a specific environment. The environment causes unnecessary pollution.


High silica glass fiber rewind

Generally, a plurality of high-silica glass fiber yarns of a selected count are rewinded and combined as an insulation of a high-temperature wire to make the wire finer, smoother and softer. When the rewinding, the high silica glass fiber yarn is placed on a specific bracket, and the fiber yarn is extracted by the upper drawing method and the tension of each strand is controlled, and the honeycomb frame is wound around the special frame of the wrapping equipment. If the tension of the fiber yarn is improperly controlled, the combined high silica glass fiber yarn will be loose and uneven, the thickness and thickness are inconsistent, and the surface is rough; on the contrary, the combined high silica glass fiber yarn has uniform thickness and smoothness. The cleaning problem of high silica glass fiber yarn combined with rewinding must be paid attention to. Once the dust invades the combined high silica glass fiber yarn, the dust will always exist and cannot be removed, resulting in high temperature resistance and insulation performance of high temperature resistant wire. The performance in terms of transmission loss and so on is rapidly reduced, which will affect the service life of high temperature resistant wires in severe cases.


Insulation winding

Insulation winding in the process of high-temperature wire manufacturing is a very critical process. The insulation must be strictly controlled to control the pitch and outer diameter of the high-silica glass fiber yarn. The key is to select a reasonable matching gear and strictly control the high. The yarn tension of the silica glass fiber yarn. The wire after winding should be smooth, round and round. It can be seen from the required dimensions of the new high temperature resistant wire that the thickness of the high silica glass fiber insulation layer is only 0.2 mm, so the winding process is quite high.

   

The conductor of the high temperature resistant wire is wound on a special wrapping machine for the high silica glass fiber yarn. Generally, the wrapping head of the wrapping machine has two types of tangential and concentric. The advantage of the tangential wrapping is that after wrapping the wrapping material on the special skeleton, it is not necessary to cut the main conductor when adding the material, so as to ensure the continuous length of the processed wire; the disadvantage is that the wire swaying is large during winding and the high silica glass The fiber yarn affects the subsequent process after the fibers are raised through the plurality of transitional guide wheels. Tangential wrap is a good way of winding when winding other materials, but care should be taken when winding high silica glass yarns or similar materials. The advantage of the concentric wrapping is that the wire swaying is small when winding, and the transitional guide wheel passing through the high silica glass fiber yarn is also less, the pilling phenomenon is not severely tangled, and the tension adjustment during the wrapping is also convenient; The disadvantage is that when the wrapping material on the special skeleton is finished, the main body must be cut when the material is added, and then the disk is changed, threaded, and rewired, which brings certain inconvenience to the wrapping operation. Regardless of the form of wrapping, the winding direction of the first layer wrapping and the second layer wrapping must be reversed. If multi-layer winding is required, the principle must be observed that the winding direction of the winding must be opposite to the direction of the upper layer, so that the surface of the wire is very compact, smooth and flat, and the entire insulating layer is fine and uniform. In the wrapping, we used a smaller winding pitch. After winding, the surface of the wire was very smooth and smooth. Finally, the outer diameter of the wire was controlled within 1.1 mm, which met the requirements of the new high-temperature wire technical specifications.


Coating

When wrapping high silica glass fiber yarns, it is necessary to simultaneously coat the organic high temperature resistant coating material. Since the high-temperature coating material is generally a relatively thin liquid (such as water), a container can be placed between the discharge of the wire and the winding head. When the wire passes through the container containing the high-temperature coating liquid, the surface of the conductor is coated with a high-temperature coating liquid. Infiltrated coating. The coated wire of the high temperature coating liquid completes the first layer of the high silica glass fiber yarn by the first wrapping head; then the secondary coating is carried out through the container containing the high temperature coating liquid; then the second winding is performed The toe cap completes the second layer of high silica glass fiber yarns; it is again coated three times through a container containing a high temperature coating liquid. According to the technical specifications and design requirements of the new high temperature resistant wire, we selected the appropriate number of layers, the coating immersion liquid and the number of coatings, so that the high temperature wire meets the design requirements. Attention must also be paid throughout the wrapping process:

a. Cleaning of the production environment (especially the coating container).

b. The ratio and concentration of the coating liquid are preferably 18 to 26 ° C at the time of manufacture.

c. The circumferential surface of the wire does not allow dripping.


Baking and sintering

Before the surface of the high silica glass fiber yarn is not dried, the wire can not be wound up. It can only be closed after high temperature baking and sintering in the sintering furnace, and the surface of the wire is dried. The baking temperature and baking time should be considered in the baking and sintering. The baking temperature is determined by factors such as the material of the wire, the geometry of the wire, and the ratio of the immersion liquid. If the baking temperature is too low, the surface of the wire will be dry, and there will be residual unsintered immersion liquid inside the insulation, which will affect the electrical properties of the wire. If the baking temperature is too high, the wire will be burnt, which will affect the mechanical properties of the wire. Even the wire is damaged and cannot be used. The choice of baking temperature must also be considered based on the time of baking and sintering. The baking time is generally determined by the time the wire stays in the sintering furnace. Appropriate baking temperature and necessary baking time will make the surface of the final high-temperature resistant wire dry, smooth, flawless, and free of peeling, and the wire can be bent freely. The wire can be evenly discharged to the appropriate wire tray through the wire take-up device.

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