Mechanism is a component of a machine. Although various mechanisms have different roles and structures, there are some common characteristics among them.
1. These mechanisms are composed of man-made entities components.
2. The entities that make up the mechanism have a defined relative motion between them. While completing the transmitting and transforming of motion, they also complete the transmitting and transforming of force.
Therefore, a mechanism is a combination of entities with certain relative motion.
Picture 1 shows the foot pedal power transmission mechanism of the sewing machine, which consists of foot pedal 1, connecting rod 2 and crankshaft 3. During operation the foot pedal is stepped so that the pedal swings back and forth around the fixed axis O-O, and through the connecting rod 2 the crankshaft 3 is rotated, and finally the sewing machine is driven by the belt pulley 4 via the belt for sewing operations. The relative positions of the entities of the mechanism are determined, and the relative movements are also determined.
Sewing machines are made up of a combination of various mechanisms, such as plane linkage, cam mechanism, gear mechanism, timing toothed belt mechanism and space linkage mechanism are common.
I. Planar linkage mechanism
1. Crank rocker mechanism
Picture 2 shows the transmission schematic of the sewing machine pedal mechanism. In this crank rocker mechanism, the foot pedal 3 oscillates reciprocally called rocker, and the crank 1 is driven by the connecting rod 2 to complete the whole cycle of rotation.
In the crank rocker mechanism, when the crank is short, an eccentric wheel is often used. Figure 3 shows the tooth lifting mechanism of an industrial flat sewing machine, where the tooth lifting eccentric wheel 2 fastened to the spindle 1 rotates with the shaft, drives the rocker 4 to swing through the large connecting rod 3, and gives the cloth feeding teeth 8 an up and down movement through the tooth lifting shaft 5, rocker 6 and small connecting rod 7.
2. Double rocker mechanism
Picture 4 shows the double needle bending mechanism of GN1-1 overlock sewing machine. The big bending needle frame 1 swings back and forth around axis O1, and the small bending needle frame 3 swings around axis O2 through connecting rod 2. The big bending needle frame 1 and connecting rod 2 can be regarded as rocker, and this kind of mechanism becomes double rocker mechanism.
3. Crank slider mechanism
Picture 5 shows the needle mechanism of a sewing machine. The rotation of the needle bar crank 1 drives the reciprocating motion of the needle bar 3 along the fixed guide path through the connecting rod 2, and this type of machine is called a crank slider mechanism. Figure 6 shows a straight knife reciprocating cutting machine cutting mechanism, which is also a crank slider mechanism.
II. Space linkage mechanism
Picture 7 shows the double bending needle drive mechanism of the GA300U101 overlock machine. The needle bending ball crank 1 at the left end of the main shaft drives the rocker 3 through the connecting rod 2 to complete the reciprocating swing around the large needle bending frame O1-O1, this mechanism is a space crank connecting rod mechanism.
III. Cam mechanism
In sewing equipment, many components require complex and precise movements, and the cam mechanism uses the specific contoured surface of the cam to push the follower to complete the intended movement. Therefore, cam mechanisms are widely used in various types of sewing machines.
Picture 8 shows the cam thread picking mechanism of the sewing machine. When the main shaft rotates, the cam groove will drive the thread picking rod 4 through the roller, so that the picking rod pivot point K completes the predetermined movement pattern and completes the thread feeding, thread collecting, thread tightening, thread pulling and new thread in stages in one sewing with other mechanisms, so that the sewing can be carried out smoothly.
IV. Gear mechanism
The gear mechanism transmits the motion accurately and reliably and has more applications in sewing machines.
Picture 9 shows a diagram of the transmission of the spindle of an industrial sewing machine through two pairs of bevel gears to drive the shuttle shaft. The upper shaft 1 transmits the rotational motion to the vertical shaft 2 through a pair of bevel gears, and the vertical shaft 2 then transmits the rotational motion to the lower shaft 3 through a pair of bevel gears to make the shuttle move.
In addition, synchronous toothed belt transfer movement is accurate, and due to the role of the synchronous belt flexure, the transfer of motion vibration noise are greatly reduced, in recent years also in the sewing machinery to obtain more applications.
In recent years, with the maturity and application of electronic control technology, the original way of transmitting motion by mechanical control of the sewing machine has gradually transitioned to computer control of the mechanism for motion and power transmission with the help of hydraulic or pneumatic components and electromagnets, which greatly simplifies the complex mechanism of the sewing machine mechanism. This has resulted in a series of new functions of the sewing machine, reducing the link of motion transmission, speeding up the response time and enhancing the action This has resulted in a series of new functions that reduce motion transfer, speed up response times and increase the precision of movements, such as automatic thread cutting, automatic thread plucking, automatic seam reinforcement, automatic backstitching, variable stitch length sewing, controlled thread tension and automatic presser foot lifting. This provides unlimited room for innovation and development of sewing machines, making it possible for our KINGMAX to overtake the world and become a sewing machine manufacturing company.
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