3.Thread - taking - up mechanism
The mechanism for conveying, recovering and tightening the needle thread is called a thread take - up mechanism. And the thread take - up rod is used in each working cycle to take up and discharge the thread and cooperate with the cloth feeding mechanism to finish the formation of the sewing thread.
Due to the regulation of sewing machine movement and take-up device and mobile sewing material,the stitch forming thread mutually sheathed after locking,meet process requirements stitch structure form is called a tight circle.The form is divided into needle bar thread take-up,link take-up,cam take-up,slide take-up,rotary disc take-up etc.At industrial sewing machine manufacture,in general,the most common is adopts link take-up, needle take-up.
Pick the working characteristics of mechanism lies in the take-up hole up and down movement of the motion curve of GC type industrial sewing machine has a branch when leaflike, take-up lever moves downward, one is for the line to the sewing needle two is decreased; when the hook live face line, and to the supply side of the hook line, until the surface line round the bobbin frame after the end. When the thread rod moves upward, it bears the face line from the shuttle frame joint has been formed and will emerge in the stitch pull tight, form a tight stitch, and from the ball out of line surface preparation for the formation of a stitch. In general, pick the stroke and the motion trajectory of the rod is relatively fixed, because of its subordinate status, determines the mechanism of all relevant dimensions is unlikely to be adjusted, should be strictly in accordance with the requirements of the installation location.
For some joints, such as rotating shuttle, depending on the type of sewing material, the type of rotary shuttle can be divided into N models.The main difference is that the length of the hook is different from the control degree of the opposite line in the winding process, which is aimed at soft thin material, common material, thicker hard material or special seam.
Wire spring, wire clamping device and slow wire hook are all subordinate to the wire lifting mechanism. Adjusting the tension and winding accessories properly is an important condition for keeping good thread trace. In addition, the feeding time of the cloth feeding mechanism is wrong. When there is a large error in the unwinding time, the tightening effect of the wire ring will also be affected.
The process of moving the seam material a distance from the original position so that the next line trace is formed in the new position is called feeding.The common ways of feeding are: lower feed mechanism,upper feed mechanism,needle feed mechanism (needle). Lower compound feed mechanism,upper, lower compound feed mechanism,upper, needle,lower integrated feeding mechanism,differential feeding mechanism,roller feeding mechanism,belt feeding mechanism.In most cases,the feed movement is a composite motion.The combination of horizontal motion and vertical movement,it is a closed curve movement,the feeding teeth in each needle pitch to rise,drop,forward,backward alternately,when the feeding teeth finished feeding movement.So it go down again to the needle board with the seam material back to the original position,ready for the next feeding action.
The feeding process should begin after the straight needle leaves the seam material,and end the feeding movement before the next sewing process.Take the flat sewing machine as an example.It’s positioning standard is that when the needle rod height and the feeding tooth height are normal,when the straight needle tip (needle eye) drops to the plane of the needle plate,the feeding tooth is level with the needle plate.This is what we usually call triple synchronization.Otherwise,there will be bad cloth feeding,wrinkle of seam,broken needle and influence thread tightening and so on.
Because of the action of the presser foot,a friction force is generated between the sewing material and the sewing material,the gap between the sewing material and the cloth feeding tooth is reduced,the friction force between the presser foot and the sewing material is reduced,the smoothness of the presser foot and the sewing material is reduced, the pressure of the presser foot can be appropriately reduced under the condition that the feeding effect is not affected, the engineering plastic presser foot and the like with small friction coefficient are selected.
The pressure size of the foot is decided according to the nature of the seam material, when the seam material is strong and thick,the pressure should be greater,the pressure when the seam material is soft or thin should be smaller.The height of the feeding teeth and the tooth distance should also be different with the thickness and thickness of the seam material.The method of tooth spacing selection: coarse teeth are medium thick materials,thin teeth are thin materials.We should also pay attention to the corresponding parallelism,flatness and distance between the feeding teeth in the needle plate slot and the same direction as the feeding teeth.The needle distance of the industrial sewing machine is usually in millimeters.The closer the needle distance is, the larger the wire consumption is.The thickness of different sewing material and the same seam material or different parts should be chosen.
The reason for the formation of the bottom line coil is that the wire hook does not need to puncture the seam material,the head should be done thicker,the side has a protruding belly shape,so that the original sewing line on the line hook naturally forms a triangle gap. In addition.The shape of the triangular coil should be stable and there should be enough coil space,which should be realized by means of the bottom line winding device and the retraction potential of the hook itself.
The sewing equipment belongs to one of the precision machines , and the sewing quality can be influenced mainly by the cooperation of four mechanisms ( including other auxiliary mechanisms ) . As the management and maintenance personnel of the sewing equipment, the coordination conditions, the time requirements , the dimensional parameters and the geometrical shapes and smoothness of each main part are comprehensively analyzed and researched, so as to ensure the accurate and reliable debugging and maintenance work, and the normal lubricating maintenance and proper operation can be carried out so as to achieve good sewing effect.