Sectional heating system for plastic calendering rollers and control method of sectional heating system

Abstract

The invention provides a sectional heating system for plastic calendering rollers. The plurality of calendering rollers are arranged on a plastic calender, and roller body of each calendering roller is divided into plurality of annular heating areas with sections adjacent to one another; each annular heating area is separately provided with a heating device and a temperature measuring sensor for measuring the temperature of the corresponding section of annular heating area, the heating devices are connected with a plurality of heating control panels, the plurality of heating control panels arearranged in a complete set with the heating devices and connected with the heating devices in a one-to-one correspondence mode through heating electric collecting rings; and the temperature measuringsensors are connected with temperature controllers through temperature measuring signal collecting rings, and the heating control panels are connected with the temperature controllers through signalwires. The invention also provides a control method of the sectional heating system for the plastic calendering rollers. According to the sectional heating system and the control method thereof, not only is the control of the temperature of the plastic calendering rollers effectively improved, but also the temperature difference between the middle of each calendering roller and the two ends of each calendering roller is controlled within the required range, and the problem of three high and two low when a film (sheet) is produced by the plastic calender equipment is solved.

Description

technical field [0001] The invention relates to the field of calendering rolls, in particular to a segmented heating system for plastic calendering rolls and a control method thereof. Background technique [0002] The calendering process of plastics is a processing method widely used in the production of plastic films (sheets). The thermoplastic is extruded from the gap between the two rollers under the extrusion of the two calender rollers of the plastic calender to form a sheet (film) with uniform thickness, such as figure 1 as shown ( figure 1 Middle 101 is raw material, and 102 is calender roll, and 103 is finished product). When the calendering roller is working, it bears a large separation force, which makes the calendering roller deflect and deform like a planted beam, and the deformation value expands from the midpoint of the roller axis where the deflection is the largest to both ends and gradually decreases , resulting in a phenomenon that the calendered film is...

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Problems solved by technology

[0003] However, the heating of the traditional calender roll is horizontal heating. The temperature difference in the axial direction of the roll is affected by the cooling of the lubricating oil at the bearing position on both sides of the roll and the absence of material on the roll. The two ends of the roll are easier to dissipate heat than the middle part. As a result, the temperature at both ends and the middle of the calendering roll processing area is inconsistent, the center temperature of the roll temperature is high, and the temperature at both sides is low, such as figure 2 shown

Because the temperature deviation affects the stability of plastic processing, there are the following problems: (1) Since the two ends of the roller are easier to dissipate heat than the middle part, the temperature at both ends of the roller is lower than that in the middle, and the area with low temperature on the roller is radial The thermal expansion of the film (sheet) is small, which will cause a large change in the axial roller gap value, which will lead to an increase in the thickness of the film on both sides in the transverse direction; at the same time, the film (sheet) will be stretched at the high temperature of the calender roller during peeling and stretching. It will also cause thick edges of the plastic film (sheet) during the calendering process; (2) Due to the movement of the material in the gap between the rollers of the calender, the material with high temperature moves towards the material with low temperature, resulting in flow on the surface of the sheet (3) Causes the fatal flaw of calendered plastic film (sheet) products with three highs and two lows (high on both sides and in the middle)

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