Improved Design of New Type Al-alloy Heald Frame
The rise of weaving machine speed has brought up a higher requirement for the performance of the heald frame. The material of the heald frame has been developing from original wood and metal to currently using al-alloy, and even more outstanding complex material like carbon fiber.
Before the year 2011, STEEL HEDDLE has used carbon fiber, unique glass fiber, and composite carbon fiber as material for heald frame components. Staubli company had already developed ultralight heald frames, with a maximum speed up to 1100rpm.
Carbon fiber has more performance advantage over glass fiber as the material of the heald frame. However, the price of the carbon fiber heald frame is high, about 3 times the price of the al-alloy heald frame. Composite material combined with carbon fiber and al-alloy can primarily increase heald frame performance, and it’s costly is relatively reasonable.
Here we would like to talk about enhancing al-alloy heald frame’s adaptivity in new type weaving machines through adding carbon fiber in the heald frame cross beam, applying damping material, changing heddle structure.
1. The Composition of Heald Frame
Heald frame mainly consists of the cross beam, side stay, heddle rod, guide board, and heddle, see Fig. 1.
1-side stay, 2-upper cross beam, 3-guide board
4-heddle rod, 5-heddle, 6-lower cross beam
The rigidity of the cross beam and side stay determines heald frame vibration resistance. The motion of weaving heddles in high-speed running affects shedding sharpness and abrasion of the yarn and finally determines fabric quality. We have researched the al-alloy heald frame to improve its structure and, hence, enhance previously mentioned characteristics.
2. Structure Improvement for Heald Frame
Improvement of the heald frame dynamic performance is necessary. The methods are applying high strength and lightweight material for heald frame, changing structure and connection mode of the main parts, and adding auxiliary components on the main parts of the heald frame. Here we mainly improve the cross beams and heddle.
2.1 Cross Beam
Improvement of the cross beam has been made in three aspects. Firstly, to padding a rectangular piece of carbon fiber at the top side of the cross beam, second is to padding a rod of carbon fiber at the bottom side of the cross beam; third is to install damping material between beam bottom and heddle rod. Refer Fig.2 to check cross-section of the cross beam before and after improvement.
a) Before improvement b) After Improvement
1-rectangular piece of carbon; 2-rod of carbon; 3-damping material
Under ideal condition, the abrasion between the heald frame and yarn mainly takes place at the position of heddle eye. However, as the movement of heddle is free on the heddle rod, and the movement intensifies as loom speed increases. The continuous contact between heddle and yarn that not penetrated heddle eye increases the abrasion of warp yarn. With the quantity of heald frame and heddle increase, the shedding sharpness is also affected.
To solve the problem mentioned above, we can install a magnet piece on the front and backside of the heald loop, the same magnetic pole between every two adjacent heddles. Homopolar repulsion forces the heddles to array evenly on the heddle rod, see Fig.3. It helps to reduce yarn abrasion and clear the shedding. Heddle rod and heddle should choose stainless or resin material to avoid the magnetic force.
Fig.3 Add magnet between each two adjacent heddles
By filling carbon fiber at the top side and the bottom side of the cross beam and filling damping material in the middle cavity, heald frame vibration and noise can be efficiently lowered.
Heddles made by resin material can reduce abrasion to warps, lower down the impact and vibration between weaving heddles and heddle rod.
Installation of damping material between the bottom of the cross beam and heddle rod is an effective way to lower down the impact between weaving heddles and heddle rod.
Adding magnet to the weaving heddles helps heddle to array evenly on the heddle rod, beneficial to reduce yarn abrasion and clear the shedding.