In the production process of shoe making, upper stretching is the beginning of the upper and bottom combination process, and also the key process in the whole production process.
(1) Preparation before stretching. Due to the different assembling methods of the upper bottom and the different stretching methods, the preparations before stretching are also different. This paper introduces the preparation work before lasting, such as the preparation of upper, last, sole, accessories and other tethers (lace up shoes), the main heel inner covering back to soft, and then the upper preformed nails repair the inner bottom and hang the upper to form the upper.
(2) Stretch molding.
1) Last stretching. Because the operation of lasting is to press the upper foot to stretch the upper surface of the foot through the lasting nail, because there is a neat circle of nails along the last on the bottom stubble after lasting, it is also called row nail.
Forming method of front stretching and back nailing: the technological process is to prepare the main heel of leather upper, shoe last, bottom material, auxiliary material, etc., the preformed nail of back soft back upper of inner package, the front upper of front stretching and the heel part of waistpit nail by repairing inner bottom and hanging.
One time bandage forming method: the technological process is to prepare the upper, last, bottom material, auxiliary material, etc. to tie the main heel, inner head and the lower mouth of the upper to brush glue, dry and activate the last bandage, heel bandage and waist socket to hammer and shape.
Stretch molding method: lock the hemp rope or nylon rope on the upper side, and pull the rope to make the upper material stick to the last.
2) Machine stretching. According to the classification of bandaging parts, it can be divided into pre bandaging machine, mid bandaging machine, post bandaging machine, mid bandaging machine, combined bandaging machine, etc.
The upper stretching machine is used to complete the upper stretching molding with the auxiliary function of the mechanical pressing tightener and the sweeping knife. The utility model has the characteristics of large extension capacity, uniform force, high labor efficiency and low labor intensity. It is the main method used in mechanized production.
3) Last forming method. The shoe last is pushed into the shoe sleeve through a certain force, and the force is awesome from the inner cavity of the shoe, and the way of making the support to reach the last type is through the extrusion, punching, and top, etc., which is called the last row method, also known as the last break method.
This method has the advantages of short production cycle and simple operation, but it is easy to have the characteristics of poor upper, insufficient hardness of main heel and inner head, and easy deformation of finished shoes. Therefore, this method is applicable to footwear products with softer upper materials.