Weft insertion mechanism

Weft insertion mechanism

Projectile looms use projectile shuttles to actively insert weft. This weft insertion method has the characteristics of low energy consumption and high weft insertion rate. The weft insertion rate can reach 1300m/min. During the entire weft insertion process, the brake of the weft thread is automatically adjusted and controlled through programming, and it has electronic monitoring of the shuttle flight, electronic control and automatic correction of the shuttle brake, and automatic adjustment of the sensitivity of the weft detector (weft breakage automatic stop device) function.
The weft insertion principle of projectile loom is shown in Figure 4-1.

(1) The projectile shuttle 6 begins to be sent from the conveyor chain 13 to the position of weft insertion: at this time, the shuttle clamp jaws gradually open and approach the weft insertion clamp 1 holding the weft yarn head. . At the same time, the tension balance bar 2 is in a high position to tension the weft yarn, and the yarn presser 3 compresses the weft yarn.
(2) The projectile shuttle 6 reaches the weft insertion position: at this time, the open shuttle clamp jaws are aligned with the jaws of the weft insertion clamp. The tension balance bar 2 and the yarn presser 3 maintain the above state.
(3) Complete the handover process of transferring the weft yarn from the weft delivery clamp to the shuttle clamp: At this time, the shuttle clamp jaws are closed to hold the weft yarn, and the weft yarn clamp jaws are opened, which completes the weft yarn exchange process. At the same time, the projectile hook 6 is ready to fly to the shed, the yarn presser 3 begins to rise, and the tension balance bar 2 begins to fall.
(4) Shuttle picking: The projectile holding the spinning yarn flies from the weft insertion side through the shed to the shuttle making side. At this time, the weft yarn is unwound from the weft feeder 4 (5, 7, and 8 are yarn guides). The yarn presser 3 is raised to the high position to release the brake on the weft yarn, and the tension balance bar 2 is lowered to the horizontal position.
(5) Shuttle making and projectile retraction: After the shuttle 6 is braked on the shuttle making side, rely on the shuttle retractor (not shown in the picture) to push the shuttle back to the edge of the cloth . The purpose of this action is to control the length of the weft yarn hooked into the edge of the cloth within the minimum limit (1.2 ~ 1.5cm). At this time, the yarn presser 3 compresses the weft yarn to the maximum extent, and the tension balance bar 2 rises slightly. In this way, the weft yarn (in the shed) that has been relaxed due to the retraction of the projectile can be tightened to an appropriate degree. At the same time, the weft clamp 1 moves close to the edge of the cloth, and the jaws of the weft clamp begin to open for the second time.
(6) The weft yarn is intended to be clamped: At this time, the centering device 11 approaches the weft yarn and pushes the weft yarn into the open weft clamp jaws. The yarn clamps 9 on both sides clamp the weft yarn close to the cloth edge. The opened scissors 10 rise to the weft yarn and intend to cut the weft yarn, and the yarn presser 3 and the tension balance bar 2 still maintain the same position as above.
(7) The weft delivery clamp completes the yarn clamping action: At this time, the jaws of the yarn delivery clamp 1 close for the second time and clamp the weft yarn. The opened scissors 10 rise to the weft yarn year and intend to cut the weft yarn, and the yarn presser 3 and the tension balance bar 2 still maintain the same position as above.
(8) Weft cutting: At this time, the scissors 10 cut off the weft delivery clamp 1 and the edge yarn clamp 9 on the weft insertion side, and the shuttle clamp jaw of the projectile on the shuttle making side is opened again, and the weft yarn head Take it out from the jaws, so that the weft yarn in the shed is held by the edge yarn clamps 9 on both sides. At the same time, the projectile hook on the shuttle making side is pushed into the conveyor chain 13, and then sent back to the weft insertion side by the conveyor chain.
(9) The weft delivery clamp begins to move toward the weft yarn handover position: At this time, the weft delivery clamp 1 holds the weft yarn and moves to the left. The yarn presser 3 still brakes the weft yarn, and the tension balance bar 2 continues to rise, and tightens the weft yarn that has been relaxed due to the outward movement of the weft delivery clamp. The two edge yarn pliers 9 and the steel reed move to the fabric fell at the same time, driving the weft yarn into the fabric fell, while the weft yarn heads on both sides of the cloth edge are still held by the edge yarn pliers. At this time, scissors 10 descend.
(10) The weft delivery clamp returns to the weft yarn transfer position: At this time, the weft delivery clamp 1 returns to the left position again, which is the position where the weft yarn transfer occurs with the shuttle clamp. The tension balance bar 2 rises to the high position to keep the weft yarn tensioned, and the weft yarn head clamped by the edge yarn clamp 9 is hooked into the shed by the left and right hook needles 12 to form a cloth edge. At the same time, another projectile shuttle starts to be sent from the conveyor chain 13 to the weft insertion position on the weft insertion side.
The weft insertion system of the projectile loom includes the projectile, projectile guide, projectile yarn clamp, weft tension rod, single-color, two-color, four-color, and six-color weft insertion mechanisms, and electronically controlled weft brake device, weft feeder, electronically controlled projectile brake, shuttle opening device (shuttle receiving side) and shuttle pressing device, etc.
1. The shuttle guide teeth in the reed holder adopt high-precision, small-shaped guide shuttle teeth. In order to improve the quality of the fabric, the shuttle guide modules are arranged in a staggered manner, which reduces the influence of the tension on the warp yarn, increases the weft yarn outlet, and reduces the friction accordingly. The single piece guide shuttle teeth are mainly used in some special types of weaving.
2. Projectile hook
There are three types of projectile hooks: D1 type steel projectile hook with small cross section; D2 type steel projectile hook with large cross section; D12 type small cross section and large clamping surface Steel projectile hook; K2 type large cross-section synthetic projectile hook.
P7300 projectile loom is equipped with: D12 type and D2 type steel projectile loom. The weft clamping surface of D12 type projectile is 3.8mm×5mm. Shuttle body size: length 89mm, width 14.3mm, height 6.35mm. Since both sides of the shuttle body are parallel and the yarn clamp in the bobbin case is fixed with steel pins, it is very simple and convenient to replace the yarn clamp.
D2 type projectile, the size of the projectile is increased, the weight is increased by 30%, the weft clamping surface of the yarn clamp is 4mm×5mm, it is mainly used for very thick weft yarns and wide width looms. Shuttle body size: length 89mm, width 15.8mm, height 8.5mm. The clamping force of the yarn clamp is 600~3500g.
3.D12 typeProjectile yarn clamp
The D12 type projectile yarn clamp has the function of shock absorption and damping. The clamping surface of the yarn clamp has a perfectly smooth plane clamping surface, a grooved clamping surface, and a clamp equipped with a padded clamp. Holding surface, clamping surface with diamond knurling. As shown in Figure 4-2.

4. Single-color, two-color, four-color, and six-color weft insertion mechanisms
Single-color weft insertion mechanism has no limit on the effective width of the loom. Its mechanism is the same as that of two-color and four-color weft insertion mechanisms. , but does not have a color selection device, and is equipped with a weft tension rod and a weft feeder in the longitudinal direction.
The two-color weft insertion mechanism is equipped with an electronically controlled two-color color selection device, which is controlled by a simple electromagnet. It can be used for single-color weft insertion, mixed weft insertion and programmable control of two-color weft insertion; The color selection operation program is compiled through the on-board computer terminal or the centrally controlled computer software smartweave.
The four-color weft insertion mechanism (SMA4) is equipped with an electronically controlled four-color color selection device. It uses a servo motor to directly drive the color selection device and cooperates with the electronic dobby or pedal opening mechanism (or jacquard machine).
The six-color weft insertion mechanism (MSA6) is equipped with an electronically controlled six-color color selection device. Like the four-color color selection device, it uses a servo motor to directly drive the color selection device, and an electronic dobby or pedal opening mechanism. (or jacquard machine) to match. The advantages of using a servo motor to directly drive the color selection device: when doing three-level jump color selection, there is no need to reduce the speed of the loom; a large number of mechanical parts are reduced, and the structure is compact; when the weft yarn is broken, the weft yarn replacement can be automatically executed.
5. Electronically controlled weft braking device The electronically controlled weft braking device and the weft tension rod form a weft tensioner. Its function is to ensure that the tension and position of the weft are accurate during the entire weft insertion process.
The braking process of the electronically controlled weft braking device:
(1) Before the loom throws the shuttle, the signal disk installed on the main shaft of the loom sends a signal to cause the weft brake device to operate before the loom shuttle open.
(2) When the projectile shuttle flies to a certain distance from the shuttle box, the trigger installed on the reed base sends a signal, causing the weft yarn braking device to start braking the weft yarn. The braking force is Size can be manipulated programmatically.
(3) The optimal braking time is determined based on the weft insertion speed and the characteristics of the weft yarn, and the delayed braking time can be controlled through programming.
The electronically controlled weft braking device of the P7300 projectile loom has three types: single or two brake shoe brakes, comb brakes and spring leaf brakes. The weft braking force of these three types of electronically controlled weft braking devices are all achieved by electronically controlled stepper motors.
(1) Single or two brake shoe braking device: A single or two brake shoe braking device is composed of brake shoes, brake thin steel sheets and stepper motors. Through the stepper motor driving the brake shoe to the different pressing degree of the brake thin steel sheet, the weft yarn generates different friction forces between the brake shoe and the brake thin steel sheet, thereby realizing the braking of the weft yarn. The single or two brake shoe braking device is mainly used for short fiber spinning yarn; for twisted synthetic fiber filament spinning yarn, the maximum count is 1000dtex. The advantage of this braking device is that the braking effect on the weft yarns is gentle and gentle, and the braking force of each weft yarn can be individually programmed and controlled.
(2) Comb brake braking device: As shown in Figure 4-3, the comb brake braking device relies on the moving yarn guide frame 1 to move downward, so that the weft yarn moves between the moving yarn guide frame grid 3 and the fixed comb The yarn guide holes of the shaped yarn guide frame 2 are folded, thereby producing a certain braking resistance to the weft yarn. The characteristics of this braking device are: the braking effect on the weft yarn is gentle and gentle; the braking force of each weft yarn can be independently programmed and controlled; the weft yarn contacts a highly wear-resistant ceramic yarn guide.

The comb brake is equipped with three different pitches for weft yarn selection:
13mm pitch: used for multi-fiber synthetic filaments with a special number greater than 1000dtex, or with a diameter less than 0.15mm Synthetic monofilament.
15mm pitch: used for polypropylene split film strips PP.
18mm pitch: used for multi-fiber synthetic filaments with surface PU coating, or synthetic monofilaments with a diameter greater than 0.15mm.
Others, the 15mm pitch and 18mm pitch comb brakes need to be controlled by a relatively powerful stepper motor. According to the type and characteristics of the weft yarn, the comb brake only needs to replace the top comb guide frame.
(3) Spring leaf brake braking device: The spring leaf brake braking device relies on the clamping force of the two spring plates on the weft yarn. This kind of braking device is mainly used for particularly fine wool yarns. Its characteristics are: the braking effect is soft and gentle, and the brake pads are supple and sensitive, so it can effectively reduce the weft breakage rate. This type of brake does not require the weft yarn to be tensioned in advance, that is, the tension of the weft yarn output from the weft feeder can be adjusted to a small state.
6. Weft feeder
As the weft insertion speed of projectile looms increases, the weft feeder has become an indispensable tool to ensure that the weft yarn is smoothly unwound from the package and introduced into the shed. Table 4-3 shows the configuration of the weft feeder on the P7300 projectile loom.

7. Electronically controlled automatic shuttle making device The electronically controlled automatic shuttle making device of the projectile loom and the three different positioning positions of the projectile shuttle are shown in Figure 4-4.Show. When the gripper 4 enters the shuttle box and is in the normal position I, the gripper simultaneously covers the switch coordinates S of sensors 1 and 3, and the automatic adjustment part of the electronically operated automatic shuttle making device does not respond.
When the gripper 4 enters the shuttle box and is in position II, it means that the gripper 4 enters the shuttle box too deeply. At this time, the gripper covers the switch coordinate S of sensor 3, but does not cover the switch coordinate of sensor 1. S. For every gripper that is too deep, the gripper brake will close one level. The sensor 1 on the side plate 5 sends a signal, and through the logic circuit and execution circuit of the electrical control box, the stepper electromagnet 11 drives the screw 7 to rotate one level, causing the wedge-shaped slider 8 to move one level to the right in the guide block 9. Due to the action of the wedge-shaped slider 8, the brake block 6 moves downward by one level, that is, the shuttle brake will be closed by one level.
When the gripper 4 enters the shuttle box and is in position III, it means that the gripper 4 does not enter the shuttle box deeply enough and the gripper does not cover the switch coordinate S of sensor 3: If 20 of the 27 grippers have not arrived If the switch coordinate S of sensor 3 is set, after 27 picks, the shuttle brake 10 will be released one level until a deep shuttle reaches position II. Then, the projectile brake will automatically close one more level.

When the loom is cold started, during the 1st and 2nd picks, the projectile brake will be closed by 7 levels, and will be relaxed by one level during the 3rd picks. After every 27 picks, Release one level until a deep projectile reaches position II. Then, the projectile brake will automatically close one more level.
The electronically controlled automatic shuttle-making device of the P7300 projectile loom uses a microcomputer-controlled stepping motor (the electronically controlled automatic shuttle-making device of the P7100 projectile loom uses a stepper electromagnet) to automatically adjust The tightness of the shuttle. Using a stepper motor controlled by a microcomputer to brake the projectile is more conducive to accurately controlling the step displacement of the stepper motor through microcomputer programming. Since a high-precision stepper motor produced in Germany is used, the projectile shuttle is braked. The power control is more precise, and the reliability of the electronically controlled automatic shuttle-making device is improved. Its working process is: monitor the shuttle’s arrival at the shuttle box through a sensor, and then identify the position of the shuttle. The stepper motor controlled by the microcomputer automatically adjusts the tightness of the shuttle, brakes the shuttle, and Automatic adjustment is completed within one weft insertion time. In this way, the wear of the shuttle lining plate and projectile is reduced.
8. Shuttle opening device (shuttle connecting side) and shuttle pressing device
The function of the shuttle opening device on the shuttle side is to open the yarn clip on the projectile that is pushed back by the shuttle lever, and remove the selvedge One end of the weft yarn clamped by the yarn clamp is released, and then, when the front shuttle brake is in the raised position, the shuttle is pushed into the shuttle path by the same shuttle opener.
The shuttle pressing device is shown in Figure 4-5. Every time the projectile loom rotates once, the shuttle pressing device presses a projectile hook 1 from the shuttle device 5 into the shuttle device 4, so that the projectile hook enters the shuttle chain. 2 between the two links 3. If the effective width of the fabric needs to be changed, the position of the shuttle connecting device 5 relative to the shuttle link 3 of the continuously moving shuttle chain 2 needs to be moved.

9. Liter/shuttle opener
The overall structure of the liter/shuttle opener is shown in Figure 4-6. The projectile shuttle that completes the weft insertion work is removed from the shuttle box on the right side of the loom. It is pushed out and sent to the shuttle chain. Every time the loom rotates once, a link 2 on the shuttle chain will push a projectile shuttle 3 into the shuttle lifter 1, and then the shuttle opener 4 begins to extend. The hook lifter 1 is located in the hole of the gripper 3 in the hook lifter 1, so that the jaws of the shuttle clamp are gradually opened. At the same time, the shuttle lifter 1 and the shuttle opener 4 rotate upward together, and the gripper 3 with the yarn clamp opened is moved from the vertical position. Raise to horizontal pick position. Then the shuttle opener 4 begins to descend, so that the yarn clamp of the projectile is closed, and the head end of the weft yarn sent by the weft delivery clamp is clamped. When the projectile hook 3 leaves the hook lifter 1, the hook lifter 1 will rotate downward and return to the vertical position from the horizontal hook pick-up position to accept another projectile hook sent by the shuttle chain.

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