Just like the shuttleless loom is a type of loom without shuttles, it is a commonly used loom for weaving small-batch and frequently modified patterned fabrics. During the production process, the high-speed weft insertion of the shuttleless loom consumes a large proportion of the total material consumption of the shuttleless loom. Therefore, how to effectively prevent the wear of the shuttlehead and the shuttle belt is of vital importance for saving production costs.
The hazards of wear and tear
The sword head and sword rod belt are the key components for the sword rod loom to complete the task of guiding the weft. During the weft guiding process of the sword rod loom, the weft is always under the active control of the sword head, resulting in fewer errors and higher reliability in weft guiding. Once the sword head is worn out, it will lead to weft guiding failure, and in severe cases, it may even cause a large number of weft breaks, affecting the quality of the fabric. --kongfz
Assuming the loom operates at 400 revolutions per minute and runs for 20 hours a day, the shuttle head makes up to 960,000 reciprocating movements each day. Over a long period of operation, the shuttle head is bound to wear out. The most vulnerable parts of the shuttle head are the head, the two wings, and the bottom. Each time a weft thread is drawn, the shuttle head is subjected to friction from the warp thread, the guide hook, the walking frame, and the guide rail. When the two wings of the shuttle head are severely worn and form knife-like edges, it is prone to cause the warp thread to break, and even make the shuttle head break away from the control of the guide hook and jump out of the shed, resulting in a large number of broken threads.
2. Causes of Wear and Tear
Production practice has shown that most of the damage to the shuttle heads is caused by the collision between the weft feeding shuttle head and the weft receiving shuttle head, resulting in fracture. This situation occurs due to the long-term wear of the transmission device and the shuttle shaft belt, which creates a gap that causes the shuttle head to move out of alignment. For example, the weft feeding shuttle head of the GA749 shuttle loom is relatively wide, and its frame is made of plastic. Therefore, most of the damage is to the weft feeding shuttle head. Shuttle head fractures mostly occur at the areas where the shuttle head blocks the yarn and holds the yarn. --chenjw189
The wear of the needle head of a loom is also closely related to the type of fabric being woven. Different fabrics have different wear conditions on the needle head, and the differences are significant. Fabrics with coarse yarn count and high warp density have more severe needle head wear and a shorter service life. For synthetic fiber products, the service life of the needle head is even shorter. This is because the head of the needle rubs against the synthetic fiber warp yarn repeatedly, generating heat, creating static electricity, and causing a hard layer of substance to condense at the bottom of the needle head, making it prone to breaking the warp yarn.
The composition of the sizing agent used for the warp yarn also has a significant impact on the wear degree of the blade tip. Different sizing agent compositions have different effects on the wear of the blade head.
The manufacturing structure of the loom and the wear of the shuttle head are also related. Especially when the height of the rear beam is higher and the tension of the bottom warp yarn is greater, the wear on the shuttle head will be more severe. Because the tension of the bottom warp yarn is high, as the shed gradually closes, the bottom warp yarn rises, causing the supporting shuttle head to rise as well, resulting in an increase in the corresponding upward force on the guide hook. The frictional force exerted by this on the shuttle head is thus greater, and therefore the wear on the shuttle head is more severe.
The transmission between the shuttle belt and the shuttle wheel of a shuttle loom is a special type of belt drive: The shuttle belt has rectangular holes. During the transmission process, there is both meshing transmission where the tooth root part and the hole wall of the shuttle belt come into contact, and friction transmission where the shuttle belt contacts the inner surface of the shuttle wheel; the meshing angle between the shuttle belt and the shuttle wheel is usually 120° to 180°. Under the condition of equal pitch, there is no relative sliding between the shuttle wheel and the shuttle belt, and the line speeds of the two's pitch circles are equal; when the shuttle wheel rotates in a swing-like manner, the shuttle belt undergoes reciprocating linear motion. Because the flexible composite belt has a certain rigidity, the shuttle belt needs to withstand certain bending stress when it bends. Therefore, an arc-shaped pressure plate was designed to make the shuttle belt move closely against the surface of the shuttle wheel, but the use of the arc-shaped pressure plate caused the friction between the rear half of the shuttle belt and it to increase significantly and become thinner. --kongfz
3. How to prevent wear and tear?
The tightness of the coordination between the warping movement and the opening movement of the warp yarn directly affects the wear of the anvil head. If the opening of the warp yarn occurs too early, the anvil head in the warping process has less contact with the warp yarn, while during the withdrawal process it has more contact with the warp yarn. Therefore, there is more friction and compression between the anvil head and the warp yarn; similarly, if the opening of the warp yarn occurs too late, the withdrawal process has less contact with the warp yarn, but the advancing anvil head has more contact with the warp yarn. Thus, at this time, the friction and compression between the anvil head and the warp yarn will also be more significant.
When choosing the ingredients of the sizing agent used for the warp yarn, it is advisable to select chemical sizing agents to reduce the wear on the needle tip. This can significantly extend the service life of the needle tip. At the same time, further research on the coating technology of the needle tip is necessary to enhance the wear resistance of the surface coating of the needle tip, which is of great significance for prolonging the service life of the needle tip.
In the structure of the loom, a lower height of the rear beam results in less wear on the shuttle tip. However, it is worth noting that appropriately raising the rear beam is beneficial for improving the quality of the fabric surface. The clarity of the fabric surface texture and the depth of the texture peaks and valleys are much better when the rear beam is 1000 millimeters higher than usual. Therefore, a reasonable height of the rear beam should be determined. When weaving fabrics with a high warp density, the height of the rear beam is generally about 1040 millimeters, which ensures the smooth weaving process.
The quality of the coating on the tip of the sword is of great significance for the use of the sword tip. When the sword tip rapidly enters and exits the mesh formed by the warp yarns, the warp yarns exert alternating compressive and tensile stresses on the surface of the sword tip, causing fatigue wear and shedding of the coating. The shed debris then becomes very hard abrasive particles, which, under the action of the warp yarns, cause abrasive wear on the sword tip. Over time, a height difference forms between the base material and the coating, resulting in a cutting edge, causing the warp yarn to break and causing the machine to stop.