Soft calender

Abstract

The invention relates to a soft calender and belongs to finishing machinery of papermaking machinery. The soft calender is characterized in that included angles formed by the connecting line of axes of hot rollers and soft rollers in calendering areas and the vertical direction are 20-40 degrees; transmission device driving shafts and transmission shaft heads of the hot rollers and the soft rollers are connected through universal couplings, surfaces of high-carbon alloy steel rollers of the hot rollers are hardened layers, and the hardened layers have the hardness ranging from 700 HV to 750 HV and the hardening depth ranging from 12 mm to 15 mm. Bearings of the soft calender produce no vibration and abnormal abrasion. During exchange of upper soft rollers, all that is required is to change turning directions of the universal couplings of transmission devices and perform connection again. The mechanical properties and working performance of the hot rollers are improved greatly.

Description

technical field [0001] A soft calender belongs to the field of finishing machinery and equipment in papermaking machinery. Background technique [0002] In the paper production line, the calender is the key equipment to determine the quality index of paper. The widely used soft calender equipped with hot roll and soft roll can meet the needs of calendering and finishing of different paper grades. However, there are still some problems in the material and layout of the rollers in the existing calenders: [0003] 1) During the calendering process of the paper web passing through a nip, the side in contact with the hot roll gets a better calendering effect. When the other side of the paper web needs to be calendered, the installation positions of the upper and lower calender rolls should be reversed. At this time, existing calenders require that the transmission devices of the upper and lower calender rolls also be reversed. As a result, the structure of the transmission dev...

AI Technical Summary

Problems solved by technology

When the hot roller is placed on the top, since the hot roller has its own gravity, and the soft roller also has upward support for the hot roller, when the pressure between the rollers is close to the gravity of the hot roller itself, the bearing load of the hot roller is very small or even zero. It is easy to generate vibration, causing bearing wear and affecting normal operation

It also makes it difficult to control the size of the interaction force between the hot roller and the soft roller, which makes it impossible to ensure a good calendering of the paper at the set pressure

At the same time, the upper and lower calender rolls are arranged vertically or the offset angle of the soft roll is too small, and the hot roll is directly set above the soft roll. When the soft roll needs to be maintained or replaced, a bulky special hook must be used to disassemble and install the soft roll. Time-consuming and inconvenient

[0005] 3) The material of the hot roll of the existing soft calender is mostly chilled cast iron, which is cast and formed. This material and the manufacturing method are the uneven structure of the hot roll of most of the existing soft calender. The surface hardness is low and uneven, poor wear resistance, and short service life. The hardness of the chilled cast iron roll surface is 550HV~560HV, and the depth of the hardened layer is 8mm. The depth of the layer is shallow, and it is easy to wear off the hardened layer after a short period of use, resulting in uneven surface of the roller, which can no longer complete the calendering work of the paper

The hot roller and the controllable middle-high roller shell of the existing soft calender mostly adopt casting process, which is prone to casting defects, resulting in low mechanical properties of the roll or roll shell, and easy to produce waste products

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