Research On The Offset Shoulder Surface In The Axial Direction Of The Forming Shoulder

The forming shoulder is one of the key components of the form-fill-seal verticalpackaging machine. Its construction and production quality has an important impact on theperformance and quality of the packaging material forming the bag. At present, the widelyused forming shoulder generally has a certain offset in the axial direction when it is produced.Bag forming effect with offset is better than that without offset, but there is no theoreticalreason for the offset, and the offset amount is just an approximate value (2~3mm) based onexperience. Based on this phenomenon, it discussed the following aspects of the research.Firstly, it initially researched the change of the thickness of the packaging materialflowing through the forming shoulder preliminary inquiry. It explored the material thicknessvariation from the angle of geometric nonlinearity and gave the equation of the thickness andlength variation.Secondly, it established a mathematical model of the forming shoulder which formingsurface has some offset; it explored the path and curvature variation of the material throughthe intersection curve. Based on the previous research of the thickness variation of thepackaging material, by comparing the curvature variation between the shoulder surface of nooffset and of some offset in the axial, it found that the path which the material went throughthe intersection curve will increase when the shoulder surface has a certain offset and it makesthe material and the intersection curve fitting easier and its curvature more gradual.Further, it researched and analyzed the force which the material had when it flew acrossthe intersection curve. Based on the first two aspects, by comparing the force between theshoulder surface of no offset and of some offset in the axial, it found that the force becomebigger when shoulder surface has some offset in the axial, and it is easier to make materialthrough the intersection curve, and fit more closely with the intersection curve.Finally, it carried on the experimental verification of the theoretical analysis through thedesign and production of test equipment for packaging materials and forming shoulder, andgave two suggestions of choosing the offset.