In the past, when repairing worn corrugating rolls, manufacturers often reduced the outer diameter of the rolls to ensure a high-quality repair. However, this approach led to an increased paper shrinkage rate of the core paper, resulting in more waste. For example, with a C-flute corrugating roller using 160g/m² core paper and an annual output of 6 million meters of cardboard, each repair reduced the roll's radius, increasing the number of turns per meter. This caused the unfolded length of the core paper to increase, leading to significant material waste. After subsequent regrinding, the waste continued to rise, eventually making it more cost-effective to replace the roll entirely. As a result, most corrugating rolls could only be repaired two times before being scrapped.
The "Recycled Corrugated Roller Hot Pressing Technology" offers a revolutionary solution by regenerating used corrugating rolls to meet or exceed original specifications. This method involves removing all the teeth from the roll, wrapping a segmented hot-press sleeve around the mandrel, and then re-toothing it to restore its performance. Combined with surface hardening treatment, the surface hardness of the roller can reach HRC58, with a hardened layer depth of 1.2mm. This technology is applicable to all types of corrugating rolls produced by various packaging machinery manufacturers, offering broad application potential. It also prevents issues like cratering and chipping during use, significantly extending the service life of the rolls. Using this method, the material cost saved is equivalent to about 20% of the price of a new roll, providing users with substantial cost savings.
By adopting the hot pressing set technology, the original corrugating roll is transformed into a thermodynamic combination of the mandrel and tooth sleeve, breaking away from the traditional design concept of a solid corrugating roll. Through extensive research and practical application, this technology not only successfully regenerates old rolls but also advances the localization of corrugating rolls. Achieving a hardness of HRC55 or higher using Cr/Mo nitrided steel materials was previously challenging, but with improved quality steel, the issue of uneven heat treatment affecting quenching hardness has been resolved. The pre-treated individual tooth sleeves achieve uniform internal material properties, and after strengthening treatment, they reach a hardness of approximately HRC60. This results in a service life increase of over 30%, placing this technology at the forefront in China.
Since 1997, the regenerated hot-pressed corrugating rolls have been applied in a 100m/min corrugated board production line by Xianghe Gaoshi Paper Products Co., Ltd. By the end of 1999, they were used in a 200m/min five-layer corrugated board line at Beijing Union Carton Factory. In 2000, the technology was successfully implemented in Zhejiang Shengda Group’s 2.0m wide, 150m/min corrugated board line. Later that year, it was also applied in a 2.2m wide, 150m/min line at Tianjin Foreign Trade Carton Factory. These systems operated continuously for 20 hours a day and achieved a service life of more than six months. Today, four out of the six domestic manufacturers using Langston equipment in the U.S. have adopted hot-pressed corrugating rolls.
Additionally, an innovative development comes from Beijing Si Chuang Da Electromechanical Manufacturing Co., Ltd., which introduced a ceramic-set corrugating roller with a service life exceeding 15 million meters and performance levels reaching international standards. Zhejiang Shengda Group uses these ceramic rollers on their 2.2m, 150m/min five-layer corrugated board production line, while Beijing Union Carton Factory employs them on their 200m/min five-layer line. Both systems are still in operation and have received user approval.
This content is excerpted from Keyin Media, Technical Printing·DigitalPrintingArts, Issue No. 2, 2007. Please visit the journal channel for more content..
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