Design and Position & Gesture Matrix Expression of 3-DOF Wrist of Two-color Sole Molding Robot

In the multi-color sole molding process, multiple robots instead of manual operation are used. The robot end-effector must complete the serial action of mold closing, residual material cleaning, mold opening, inspecting and up-picking of the work as the main functions and techniques. In this paper, based on the new technological process of the sole injection, robot logical action sequence, and functional requirements and mechanism theory, a wrist compact in structure and independent in motion with three degrees of freedom was designed. According to the new molding process, the three end-effectors, namely, the opening and closing actuator, the flapping residual material cleaning actuator, and the inspection and picking actuator, were connected with the wrist after logic induction and integration of action functions. By setting the local coordinate system and the global coordinate system, the unified matrix expression describing the position of the base, the arm and the wrist reference points and the gestures of three end-effectors was developed, so that the robot's action function is fully matched with the multi-color sole molding process requirements of the robot replacing the operator. Such expression provides effective methods and means for further research, test and optimization of wrist and robot systems.

I. Introduction

With the continuous improvement of living standards, people's demand for multi-functional, multi-variety, good and inexpensive shoes, especially for leisure and sports shoes with injection molded soles is the largest, about 5 billion pairs per year, and the variety and style demand is diverse, and the development trend into two-color and multi-color soles. The traditional production process of two-color or multi-color sole is to manually operate the mold on the production line, and the weight of the mold increases obviously. Several layers and stages are desperately needed in injection molding, leading the process is further complex. The mold operation for closing and opening needs repeatedly manual work with labor intensity even further increased; the technical difficulty raises, the quality stability is worse, the qualified product rate is yet lower with low productivity. Fig.s 1 and 2 show a fragment of the manual operation of the two-color sole mold. The solution is to operate robots.