## 3 Design of Piecewise Combined Continuous Accelerating Electromagnetic Weft Insertion Structure  
### Analysis of the Structure of the Weft Clamp  
The main body of the weft gripper is composed of the weft gripper shell and the weft gripper clamping device inside, as shown in Figure 4. The outer shell of the gripper has a hollow structure, and the shape of the shuttle head and body is streamlined, which is conducive to the smooth flight of the gripper. The overall weight of the weft gripper is about 50 g, and the outer dimensions are: length 90 mm, width 14 mm, and height 6 mm; the thickness of the weft gripper clamping device is 3 mm. The adoption of a new electromagnetic weft insertion device eliminates the need to apply lubricating oil to the weft grippers running on the loom, and ensures the best cleanliness of the fabric. It is not only suitable for the weaving of most common fabrics, but also for weaving fine, extra-light-colored high-grade fabrics.  
The surface of the weft gripper needs to be heat treated, then finely ground into a prescribed streamline shape, and then polished to make the surface smooth and free of burrs. Different from the traditional projectile, the weft picking method is no longer adopted because of the electromagnetic drive launching weft insertion, which diverges significantly from the process requirements of the weft gripper. The shell of the weft clamp in this paper is made of ferromagnetic material, electrical pure iron which has high relative permeability, high conductivity, and low coercivity. Pure iron is easily oxidized in the air. In order to make the ferromagnetic weft clamps reusable, the coating method, electroplating method, and chemical methods to form dense oxide film-related processes are mature, e.g., in the film forming process The introduction of Zn ions can not only combine with more TA molecules to form a thicker conversion film, but can also accelerate the film formation process and convert it into ZnO, further inhibiting iron corrosion (corrosion protection efficiency can reach 92.39%) [15]. Studies have shown that the optimal strength of TIAIN coating is almost equal to the surface strength of pure iron, and that the coating variants do not undergo oxidation corrosion, which can perfectly protect the iron surface [16]. Electrochemical quantitative studies using gallium (III) and zinc (II) metal surfactants as iron corrosion retarders in salt and acid media have shown that they have mitigating effects [17].  
The structure of the clamping surface is divided into flat clamping surface, notched clamping surface, toothed clamping surface, corrugated clamping surface, and anilox clamping surface, etc. As shown in Figure 4, the planar structure type is selected in this paper. A key part of clamping the yarn is the extra-large width automatic loom being opened and closed twice during each weft insertion process. In order to prevent fatigue and fracture during the opening and closing process, and to ensure that it has sufficient clamping force, the clamping device is made of 50 CrV steel. The clamping device is heat-treated, and a force of 30 N is pre-applied to the clamping part during manufacture.  
Figure 4: The structure diagram of the weft clamp assembly.