The width of the extruded film of the wide-width die is determined according to the rubber calendering process theory. The compressibility of the rubber volume is very small. In fact, it can be considered that the rubber is incompressible, that is, the volume of the rubber will not change before and after calendering. . Therefore, while the thickness of the rubber compound is compressed, it must be accompanied by a corresponding extension of the width and length. When calendering the rubber material flows in the direction of the force, the rubber material has a large amount of extension in the direction of the roller rotation (that is, the direction perpendicular to the axis of the roller), and the width change is small, and the spreading factor β≈1, that is to say, When calendering, the glue supply width b is close to the required product width b. Therefore, within the range of the contact angle of the calender, the greater the thickness of the glue, the greater the extension in the direction of rotation of the roller. From the above calendering process theory, the width of the film fed into the nip of the two-roll calender (that is, the width of the film extruded by the wide die) should be close to the required product width. In the wide-format head, the rubber material is split across the entire width through the fish-tail-shaped runner. Inserts can be placed in the fish-tail-shaped runner. When the width of the wide-format head extruded film needs to be changed, the insert can be replaced. To adjust.
The main technical parameters of the inner liner produced by the roller head extrusion method are as follows: extruder screw diameter D150mm; screw length; *; calender roller specification Υ400×1100mm; roller shape upper roller belt type, lower roller plane (not Belt type); Roller * high temperature 120 ℃; Calendering speed sheet * Large width 850mm; Film compound centering error ± 3.4 Main advantages and disadvantages The advantages of roller die extrusion method to produce inner lining are mainly manifested in the following aspects ：(1) The product produced has no bubbles; (2) The product thickness range is large, which can produce thicker film; (3) The wide extruder head ensures the best feeding of the calender; (4) The product precision is high , The thickness error of the entire width is small; (5) The belt-shaped film can be produced according to the tire structure design requirements. The disadvantage is that the “type cover” and equipment investment costs are high.
At present, most of the tire manufacturers in China use the roller head extrusion method or the four-roll calender method to produce the radial tire inner liner. The quality of the products produced by the extrusion method is better than that of the calendering method, but the equipment investment is also much higher than that of the calendering method, and currently it is mainly dependent on imports. Therefore, domestic tire machinery factories should digest and absorb these two production methods, and develop more economical and practical production equipment suitable for China’s national conditions under the premise that the radial tire structure design and process requirements permit.
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