Opening Mechanism – Types of Opening Mechanism
There are many types of shedding mechanisms to weave different types of fabrics. There are usually six types of shedding mechanisms: crank, eccentric, cam, dobby, jacquard and electronic shedding.
1. Crank shedding mechanism
The connection points of the crank shedding mechanism are all rotating pairs, which are beneficial to high-speed operation and are used in high-speed rapier looms and some air-jet looms. The leisure characteristic of the crank shedding mechanism is that it has a relatively short resting time. It can generally only be used to weave plain fabrics, with a complete weave of one cycle every two wefts, and is not suitable for wide-width looms. This is only its main shortcoming, but it is simple to manufacture and organize. , lower cost.
2. Eccentric shedding mechanism
The eccentric device of the eccentric drive shedding mechanism has a needle bearing set on the central shaft of the loom. The rotation speed of the central shaft is half of the speed of the main shaft of the loom. This mechanism can not only operate at high speed, but is also suitable for microcomputer control. Generally, this type of loom has no rest time during operation, and the heald frame resting is similar to the simple harmonious resting. If the drive shaft of this eccentric mechanism is driven through a speed change mechanism, like a rotary dobby, the heald frame can also be stopped for a while and used on general or wide-width looms.
3. Cam (pedal plate) opening mechanism
Cam transmission opening mechanism includes a negative cam mechanism (pedal plate) with spring return and a positive outer conjugate cam mechanism. The conjugate cam opening mechanism can avoid or reduce the impact and vibration caused by clearance during high-speed operation. This kind of mechanism is usually used on modern looms that mass-produce fabrics, especially for weaving dense fabrics with 4 to 8-page heald frames for weaving plain fabrics. It simply makes the heald frames static and asymmetric, and it is the heald frame. The flat heddle time is separated from each other, which reduces the breakage rate of warp yarns.
The cam opening mechanism is suitable for producing fabrics from 2×2 to 6×6 triple weave and its changes, including corduroy and other velvet fabrics.
4. Dobby shedding mechanism
Dobby shedding mechanism is a kind of heald lifting device. The new dobby machine can lift up to 12 to 24 heald frames. The distance between each heald frame is generally 12mm. . The circulation of fabric tissue is theoretically unrestricted and can range from 48 to 6400 wefts, and the common range is generally less than 1000 wefts. The characteristic of the dobby machines used in modern shuttleless looms is that they use fully open sheds instead of half-open sheds or closed sheds. The heald frame can stay above or below according to the requirements of the fabric weave. It can only be lifted and lowered when changing the lifting direction. In addition, the heald frame has a stopping time when the shed is fully opened. This is beneficial to the selection of lifting healds and also Helps increase vehicle speed. It does not have any wasted movement, thus helping to reduce warp breakage. The dobby mechanism is suitable for weaving small patterned tissues, such as jacquard poplin, bed sheets, bath towels, etc. It is especially suitable for weaving various woolen fabrics.
Modern dobby machines mainly have three structures:
Double-acting positive dobby – such as Stubli2232;
Double-acting passive dobby – such as Stubli2500 and 2560 series electronic dobbies;
Rotary dobby——such as Stuble2600 and 2800 series electronic dobby.
5. Jacquard machine shedding mechanism
The characteristic of the jacquard shedding mechanism is that each warp yarn is controlled by a heald line instead of a heald frame, which allows each warp yarn to stand independently up and down, allowing for complex weaving. pattern tissue. The jacquard opening mechanism can be divided into single-acting type, double-acting type, single-acting type and double-acting type. The single-action type is equipped with a set of carabiners and a tool holder. Each time the main shaft of the loom rotates, the tool rest rises and falls once, forming one shed; the double-action type is equipped with two sets of vertical hooks and two tool rests. Every time the main shaft of the loom rotates, the two tool rests alternately rise and fall once, forming two sheds. shed. In a single-tube jacquard machine, the tube must be rotated once each shed is formed; in a double-tube jacquard machine, there are two situations: one is that each tube has one pattern, which is suitable for weaving blankets and blankets with two patterns alternately arranged. The other type is to use two flower tubes to take turns each time a shed is formed, so that the movement of each flower tube is reduced by half, and the rotation speed of the flower tube can be slowed down to meet the requirements of increasing vehicle speed.
The specifications of a jacquard machine are generally expressed by the number of needles (number of needles, number of holes or number of holes), that is, the number of horizontal needles it can accommodate. 400-600 needle jacquard machines are mostly used in warp knitting machines in the knitted fabric industry. Jacquard machines with 900 to 2688 needles are mostly used in the cotton weaving industry to weave various jacquard cotton fabrics. Jacquard machines with 1400 to 15000 needles are mostly used in the silk weaving industry and decorative fabric industry to weave various jacquard quilt fabrics and decorative fabrics. Fabric.
6. Electronic shedding mechanism
The electronic shedding mechanism is a new technology. The shedding mode of each heald frame is controlled and driven by an independent servo motor. The shedding mode of each heald frame can be freely set through the multi-function operating panel. , different angles of repose and closing time up and down. Suitable for weaving some unusual fabrics.
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