Film winding breaks through Xintiandi

In the past three to five years, the coilers for cast film and blown film have changed a lot. They are now able to wind larger and better rolls with higher speed and less tension, and the rolled film is also thinner and more flexible. This is not a result that can be produced, but it is a lot. Since the mid-1990s, load cell tension controllers, tension reduction functions and AC flux-vector drives have begun to replace floating roller tension control and DC drive.

Macro Engineering USA provided its first flux-vector drive for an experimental extrusion coating line in 1990. This line wound the coated paper at 3500 ft/min. The winding speed of the paper can reach 8000 ft/min, non-fabric 4500 ft/min, because they are inelastic, porous, and do not block the gas.

The first plastic film winder with AC flux-vector drive controlled by a touch-screen programmable logic controller (PLC) is the 1011 mini-column central coiler introduced by Battenfeld Gloucester in 1991. Specifically for three-layer blown film. Two companies, Black Clawson and Reinhold, introduced their first AC vector drive and PLC controller for plastic film reelers in 1996. Five years ago, most coiler manufacturers were also producing models with AC drives and PLCs. And two years ago, virtually all brands and all models have been converted to use these technologies.

The greatest advantage of AC drives is not speed, but low maintenance. The DC drive has a brush and must be replaced. When only the outside air cools, it will run at a lower speed. AC drives have no brushes, do not need cooling, are more precise, and have a wider speed range. Recently, AC servo drives have been used to replace AC vector type drives to provide more accurate speed and position control.

DC drive speed and torque are not linear. On the other hand, vector and servo type AC motors have absolute linear torque development changes from zero to maximum speed. This means that the DC drive has a speed range of about 80:1 available, while the AC vector or servo drive has a 2000:1 speed range.

Why is such a speed range necessary? The winding shaft speed at the start of central drive winding is high and when the drum is formed, the speed is extremely low, thus maintaining a stable web surface speed. The rate of descent is at least 10:1, while the larger diameter may be 25:1. Black
According to Clawson, reels with diameters up to 60 in. and extremely thin and flexible materials may require up to 100:1 tension decrement.

The actual maximum speeds for today's cast film take-up are approximately 2500 ft/min for the Stretch Film and 2000 ft/min for the BOPP film, which was between 1500 and 1700 ft/min a few years ago. Ricky Keller, director of coating and film sales at Davis-Standard, said: "The current cast film line is no longer limited by the coiler."

Film winding works faster in secondary processing such as printing, coating and lamination. For example, the Meridian coiler from Davis-Standard Corp. is said to be able to process coated or laminated films, metallized films, and BOPP snack packages at speeds of up to 2500 ft/min. Keller said: "Because the gas needs to be exhausted during winding, the Meridian coiler can operate at a speed as fast as the membrane."

A new generation of coilers can also maintain lower tension than before at lower line speeds, which is a good thing for soft and thin reels such as pre-stretched films and blown films. The uniformity of the blown film is inherently worse than that of the cast film, so it needs to be wound loosely to make a flat roll. If the stretched film is wound too tightly, thin areas will become thinner, and thick areas will wrinkle. For thinner films, the thickness change will be small, but a roll will accumulate many layers, so the total effect of thickness variation on the quality of the roll will be greater. The blown film typically has a take-up speed of 300-350 ft/min and the stretched film is 500-600 ft/min. HDPE blown film can be coiled at 1000 ft/min.

Higher winding speeds and better tension control are changing the routine. Mirek Planeta, president of Macro Engineering, said: “We are transforming coilers for a large number of production lines around the world.” Old-fashioned coilers are being fitted with new drive motors, electronic components, and load cells at a cost of three new coilers. Two in two.

The new high-speed coiler utilizes a different roller structure from previous models. For example, the Davis-Standard 2300 cast film reel is used for a 57-in diameter reel, which has only three backup rollers, compared to five previously. All manufacturers today use backup rollers of carbon fiber materials to achieve less vibration at light weight, stiffness and high speed.

Giant rollers used in high-speed processing lines are getting bigger and heavier. Brueckner, Germany, claims to have built the world's largest reeling machine to handle 10-meter wide PP reels and 60-in diameter reels with a weight of 26,000 lbs. Since 1997, Bruckner has built four such giants.

The Battenfeld Gloucester Model 1022 Surface Winder handles rollers with a diameter of 60 inches and 7,000 pounds. (There is also a special model for 72in rollers). Gloucester's OPP cast film winder model 1037 supports 10,000-pound rolls and is also building models for 12,000-pound rolls.

Pursue zero tension

The high-precision load unit and the newer roller construction make the winding tension much smaller. Black Clawson uses a servo drive to keep the 90in spool tension down to 2 pounds, or 0.02pli ((lb/in). Windmoeller & Hoelscher uses a servomotor to keep the 100in spool tension at 4 pounds (0.04) Low) The tension can start at 10 pounds and gradually decrease to 2 or 4 pounds on the periphery of a full roll.

Black Clawson is developing a "zero tension" coiler for special membranes. The company's product manager, Robert Moeller, pointed out that this machine is sensitive to the surface of the film, maintaining a certain degree of low sag.

A better low-tension controller improves the quality of the roll of the cast PP film. This is a difficult product because after reeling it will shrink for 48 hours or longer. If not enough gas is blown into the drum, shrinkage is allowed to exist, the drum will harden, and the core may be deformed. Gerd Kasselmann, general manager of W&H's Reinhold division, believes that low tension center/surface winding can blow off a certain amount of gas between layers.

Polyethylene (PE) does not shrink so much. It is wound in a tight tube and does not allow gas to enter. These reels need to be tight at the core, while the outside is loose because the tension will be small at the core but will remain tight on the outside.

To control the low tension of the blown film, Addex last year developed a high-end surface/gap coiler called Superwind. It has 13 AC servo motors with direct torque control. Each reel has a large motor at one end and a small motor at the other end for transporting the reels. At each end of the spare reel there is a fiber-optic load unit that controls the actual tension. Based on the torque data from all drives, the Superwind Winder controls the tension and uses the load cell to correct and check the tension.

Addex president Rick von Kraus said that this system provides more precise tension control. He claims that the accuracy is between 2% and 3%, while the accuracy of the tension control done only by the load cell is 10% to 15%. "Using the load cell to control the motor speed is only accurate if slippage does not occur. If slipping occurs in a tension zone, it will affect the next tension zone, creating a suction effect."

Reifenhauser's UFA III high-speed coiler incorporates Rockwell Automation's Control Logixs Programmable Logic Controller (PLC) with induction from motors and three to seven drive rollers The data, the coiler controls the tension. The tension is measured by the signal from the high speed load unit, but it is not controlled. The load cell measures the tension deviation of the backup roller and provides an electronic signal that is proportional to the actual tension.

Instead of using pneumatic or hydrodynamic pressures, Ravenhauser uses servo drives to generate mechanical pressure on the contact drum. This servo pressure can be as low as 50 N, and it is possible to wind the elastic film in pressure instead of gap mode. The UFA III model can roll up to 59 in diameter reels.

Bigger, better, faster

Alpha Marathon manufactures tower coilers for blown film and cast film. Recently, it has introduced a high-speed rewinding machine for lining films with a winding speed of up to 1200 ft/min, which is completely replaced automatically every 20 seconds. reel.

Black Clawson is developing a new "anvil" for automatic cutting of polyester and OPP films using a servo-driven blade to impact the backup roll. The blunt edge against the backing roll cuts the polyester without letting it fall off. The servo drive accelerates the anvil support so it can run at the same speed as the membrane.

Davis-Standard has integrated high-speed cameras into EPIC controllers to enable high-speed transport of reels on its Meridian coiler. This model can now be cut and joined at a speed of 2500 ft/min.

Battenfeld Gloucester's 1002DS (Double Spindle) Winder winds the cast stretch film at 2000 ft/min, producing eight 20 in wide rolls or six 30 in rolls. Gloucester also offers a high speed twin tower coiler with its first commercial MDO unit for coextruded blown stretch film. Prior to stretching, a 0.8 to 1 mil thick film was run at 225 ft/min. After stretching, the film was only 0.25 to 0.35 mil thick and had a length four times longer, so it was wound at 900 ft/min.

Alpine is producing its first rewinding coiler with rewind capability. Its winding speed can reach 1000ft/min.

Macro Engineering manufactures a tower central coiler for BOPP drums with a diameter of 60 inches and a speed of more than 2000 ft/min. Its newest Automax C and Automax S coilers have an optional “kiss” type of winding that uses a dedicated servo-driven reel to remove gases. This linear reel is supported at both ends and is parallel to the axis of the reel. Through a touch screen, tension and pressure are controlled.

The Austrian Lansing (SML) company developed the Model 2000 horizontal gliding coiler, which can tear 16 smaller reels and meet the requirement of no-scrap cutting. It can roll a PE stretched tape into a roll with an outer diameter of 10 in. The PP cast film is wound on a 6 in core to form a 40 in. diameter roll.

Tecno, Italy, has just developed a high-speed tower coiler for cast stretch film at a speed of 1600 ft/min. It can directly manufacture a stretch film winding drum at a high speed, and each stretch film roll is usually torn and rewinded in a secondary operation. Tecno utilizes AC vector drive on the reel, and AC servo drive with controlled tension on other driven reels.

From this year onwards, Reinhold will build surface and gap coilers for W&H, and apply its drum cutter designs to surface coilers for the first time. This will allow the surface coiler to easily reverse the direction, which is generally the advantage of a central coiler.

Reinhold's patented cutting drum technology has been used in W&H's fully servo Filmatic R central coiler. The blade will cut out an acute angle and send the blade to the new core, which provides central winding from the beginning.

Coiling machine knowledge

There are three basic types of coilers: center, surface, and clearance. The central coiler has a large drive motor on the take-up shaft that can be easily turned to wind co-extruded or processed films.

The rail-type central coiler operates faster than the tower coiler, and the diameter of the reel is generally larger, but the diameter is still limited because all