Design And Research On Automatic Knotting Device Of Paper Bag Hand-carry String

Conventionally, twining a string into a designed shape calls knotting. Knotting device is a mechanized equipment which imitates twining automatically, having a very wide application prospect on packaging, medical, textile, etc. However, nowadays, paper bag hand-carry string is still knotted manually. This can’t satisfy the production requirements with the labor shortage and rising employment cost. Thus, research on automatic knotting device of paper bag hand-carry string will promote the packing industry.In this paper, a knotting prototype machine is designed through investigating the knot-tying theory of string, performing knot-tying simulation and experiments. The contents of this dissertation are introduced briefly.1. Based on knot theory, the string knot is modeled. Through it, bending and torsional energies are investigated which influence the stability of knots. According to this, analyze the reason of the difficulty of “spatial rotating knot tying” experiments and determine “pivoting knot tying”. Then, imitate the string knotting manually.2. Through the analysis of manual knotting process, the key mechanisms are designed innovatively including the clamping mechanism, the roping mechanism, the knotting mechanism and the transmission. On this basis, the influence of mechanism parameters on knotting is studied. Then determine the parameters. Finally, the geometric model of automatic knotting device is developed, whose motion process is described.3. A comparative dynamic characteristic analysis of two clamping mechanisms is performed with Adams, in order to get a better comprehensive properties one. Then the matching movement relation of the roping mechanism and the knotting mechanism is determined. Furthermore, roping simulation are conducted which paves the way for the research on the knotting experiments.4. A knotting prototype machine is built, and the string is knotted successfully.This paper conducted the study of paper bag hand-carry string automatic knotting device, and explored the key issues of string automatic knotting, which provide the foundation for further study.