Research and application of key forming technology in production of recess filters

In order to prevent broken seams cause by higher grammaged plug wrapper on recess filter and to increase the controllability of circumference and roundness of filter rods and the hardness of the recess section, the characteristics of hotmelt adhesive and high grammaged plug wrapper and the forming technologies for the roundness design and recess section length design of the base filter rods were studied. The results showed that:1) Adopting the hotmelt adhesive with a high melting point at about 180℃, the seam's bonding strength of the recess filter was the highest, with cracked seams effectively being eliminated. 2) With the increase of plug wrapper grammage, the hardness of the recess section and the roundness of the recess filter increased gradually, and the appropriate grammage for the plug wrapper ranged from 100 to 110 g/m2. 3) For the filter rod with the target circumference of 24.25 mm, the circumference and pressure drop of the recess filter rod could meet the standard design requirements when the base rod circumference was controlled at 23.60-23.70 mm. 4) The hardness of the recess section was higher when its length was 5 mm comparing with 8 mm. The composite structure of the recess filter adopted R-FF1(5+12+8), namely the length of recess section was 5 mm.