Discussion on the influence of die structure on towing rubber sleeve cable sheath
With the development of industrialization, rubber-sheathed flexible cables have always been the main equipment installation cables used in various mobile occasions due to their stable electrical performance, excellent mechanical and physical properties, especially their softness. At present, in the mining process of large open-pit coal mines and metal mines, large gravel and sharp objects often strike cables, the cable is often subject to a large drag force in the process of moving with large mining equipment, so the drag-type rubber sheathed cable relies on special structural design to reduce the influence of external torsion force on the sheath material, so as to improve the service life of the cable and become the first choice for the installation and use of equipment in dragging occasions. In the case of frequent dragging and friction, the reduction of cable life is often caused by the damage to the insulated wire core from the outside to the inside from the wear of the sheath, therefore, the service life of the sheath directly affects the service life of the cable. The towing type cable uses the traditional sheath thickness to be divided into two parts, and the structure of the braided layer is added between the two layers of the sheath to increase the binding force of the inner and outer sheath. The braided layer adopts materials with certain elastic force, to buffer the reaction of the cable sheath during the stress process, thus improving the life of the cable. The sheath realized once before is divided into two times to realize, and naturally the thickness of each layer of sheath will be thin, greatly improving the difficulty of process realization. Therefore, the choice of die for rubber materials is particularly important during extrusion. Under normal circumstances, the production of ordinary rubber-sheathed cables is realized by providing a larger pressure by the ratio of the mold core and the mold to fill the cable core. Generally, the mold core will choose a larger angle, reduce the angle of the mold sleeve (See figure 1) The angle difference between the mold core and the mold sleeve is generally controlled at about 15℃, and the extrusion pressure of the rubber material is controlled through the angle difference, and the material is extruded on the surface of the cable core under the condition of compaction. The thickness of the inside Guard and the outside Guard of the dragging type cable is relatively thin, and the production of the rubber material is extrusion type. During the production of the outside Guard, the rubber material acts on the cable core at the extrusion die, when the pressure is too large, it is easy to cause the accumulation and extrusion of the inner sheath and the phenomenon of clamping. In order to solve the above-mentioned card mold, we have gone through many theoretical designs and practical demonstrations. By improving the angle difference between the mold core and the mold sleeve, we can well solve the accumulated card mold caused by excessive external protection pressure and internal protection, the continuous production capacity of this kind of cable is greatly improved. The improved mold body is shown in Figure 2: Figure 1: mold diagram before improvement, mold parameters before improvement: α = 110 ℃, β angle is generally 89 ℃, angle difference (Alpha-Beta) Generally, it is 21 ℃, Fig. 2: The improved mold diagram, the improved α angle is generally 89 ℃, the β angle is generally 68 ℃, and the angle difference (Alpha-Beta) Generally, it is 21℃. This mode of mold matching is to reduce the α angle and the β angle. According to mechanical analysis, this angle matching can reduce the pressure on the inner sheath when the outer sheath is extruded, the extrusion of the sheath can be well ensured. After practice verification, it can be well extruded, and the surface of the sheath is smooth, no bamboo joints, etc. , effectively solve the problem of the card mold.