A new generation of winders with blown and cast films wraps larger, better rolls at higher speeds and less tension. The film winding machine runs so fast that it can push the film production line to its full production potential.
In the past 3 to 5 years, the advancement of film-filming and blown-film winding machines has made tremendous progress, allowing thinner, wider films to be wound into larger diameters at higher speeds and with less tension. Large, better quality rolls. This is not a single technological achievement, but a crystallization of several technological developments that began in the mid-1990s. These technologies include: dynamometric tension control AC flux - vector drive and DC drive.
New generation of film reclaimers
Macro Engineering & Technology tested the company's first flux-vector-driven winder in a pilot extrusion coating line that coated coated paper at 3,500 feet per minute. Paper and non-woven fabrics are not stretchy, porous, and do not collect gas, so the paper can be wound at a speed of 8,000 feet per minute and the non-woven fabric can be wound at a speed of 4500 feet per minute.
The first AC-flux-vector-driven plastic film winder controlled by a touch-screen PLC was designed by Battenfeld Gloucester in 1991 as a model 1011 compact turret center winder for winding three-layer films. . Both Black Clawson and Reinhold introduced the first AC vector drive and PLC controller for plastic film winders in 1996. As of 5 years ago, most film makers began to use AC drives and PLCs to control the manufacture of some models of film winders. As of 2 years ago, basically all manufacturers and all models turned to these technologies.
The biggest advantage of AC drives is not speed, but low maintenance. DC drives use brushes, often need to be replaced, and can only operate at low speeds when using external air cooling. The AC drive has no brushes, does not require cooling, is more precise and has a wider speed range. Recently, AC servo drives gradually replaced the AC vector drive mechanism to obtain more accurate speed and position control.
The speed and torque of the DC drive mechanism are not linear, and when the speed is below 10%, there is no torque at all. However, AC motors (vector and servo) have linear torque from zero speed to maximum speed. In other words, the available speed range of the DC drive is approximately 80:1, while the available speed range of the AC vector or servo drive is 2000:1.
When the central drive reeling machine starts winding from the shaft core, the shaft rotates at a high speed, and gradually decreases to a minimum as the film roll increases in rotation speed to maintain a constant surface speed of the film roll. Rotation speed is decremented by at least 10:1, and the decreasing ratio of the large-diameter film roll may be 25:1. According to Black Clawson, a 60-inch-diameter giant roll and a roll of thin, elastic material even require a 100:1 drop in tension.
Multiply the linear velocity range by the above ratio (the ultrathin film has a line speed of 450 ft/min, the extremely thick film has a line speed of 30 ft/min, and the range is 15:1). Then a film winding machine winds the film. The required speed range for all types of products is 1500:1.
Today, the highest possible winding speed for cast film is 2500 ft/min (elastic film) and 2000 ft/min (BOPP), while the winding speed of the two just a few years ago was only 1500-1700 ft/min. The stretch film film line is no longer limited by the film machine.
In secondary processes such as printing, coating, and lamination, the film can be wound even faster. For example, a Meridian film laminator from Davis-Standard Co., Ltd. winds coated/laminated, metallized film, and BOPP snack food wrap at 2,500 feet per minute. Keller said: "Because of the need to remove the air entrapped during winding, this may be the fastest speed to remove the film."
The new generation of reelers can also maintain an unprecedented low tension at low line speeds, which is very advantageous for soft, thin rolls and blown films of pre-stretched elastomeric films. The blown film itself is thinner than the cast film and therefore needs to be wound loosely to make a flat film roll. If the elastic film is wound too tightly, the thin place will be thinner and the thick place will swell. The deviation of the thickness of the thin film is relatively small, but the film roll overlaps many layers of the film, and as a result, the total deviation of the entire film roll becomes large. Therefore, the typical winding speed for blown film is 300-350 ft/min, and the maximum winding speed for thin or oriented films is 500-600 ft/min. HDPE blown film can be wound up to 1000 feet per minute.
Faster winding speeds and better tension control are "changing the rules," said Mirek Planeta, president of Macro Engineering Technologies. "For this reason we are refurbishing the reclaimers on many production lines around the world." Membrane machines are rebuilt with two-thirds of the cost of a new film-forming machine with new drive motors, electronic components and dynamometers.
The new high-speed film rewinding machine uses a roller structure that is different from the previous models. For example, Davis-Standard's 2300-type cast film winding machine that winds up to a maximum diameter of 57 inches is now only three rollers, which used to be five. Hosokawa Alpine American's newest center has used a more S-shaped structure to replace the driven roller of the pressure roller. All manufacturers are now using lightweight carbon steel, and carbon rollers with small deviations at high speeds.
Giant membranes on high-speed processing lines are getting bigger and heavier. Brökner (Bruckner, Germany) announced that it has produced the world's largest rewinding machine capable of winding 10-meter-wide PP reels and film rolls with a diameter of 60 inches and a weight of 26,000 lbs. Since 1997, Br焎kner has built four such giants.
Battenfeld Gloucester's Model 1022 Surface Winder winds a 60-inch diameter, 7,000-pound film roll (a 72-inch-diameter film winder was also designed). Gloucester's 1037 cast film winder, manufactured for OPP (Oriented PP), can support 10,000-pound film rolls, and a model that supports 12,000-pound film rolls is in the works.
Strive for zero tension
The precise dynamometer and the new roller structure greatly reduce the winding tension. Black Clawson uses a servo drive and a special squeeze wheel to keep the 90-inch spool tension down to 2 pounds, or 0.02 pounds per inch. Windmoeller & Hoelscher's lamination wheel was balanced to zero weight and a servo motor was used to apply only 4 pounds of tension (0.04 pls) to a 100-inch drum. The distribution of tension decreases from the initial 10 pounds to 2 pounds or 4 pounds around the entire circumference of the film roll.
Robert Moeller, product manager for Black Clawson, said the company is developing a "zero tension" film winder for specialty films that maintains a certain degree of sag by inspecting the film surface.
The low tension optimization control improves the film roll quality of the PP cast film. Since the PP cast film shrinks with the crystallization of 48 hours or more after winding, it is a product that is difficult to wind. If the film roll does not shrink enough air needed for the film roll, the film roll will harden and may crush the shaft core. Gerd Kasselmann, Manager of W&H`s Reinhold Div. explained that low tension center/surface winding can trap a controlled amount of air between layers.
The shrinkage of polyethylene is not as high as PP, and it can be wound tightly without adding air. The polyethylene film roll should be tightly wound at the core and loosely wound on the outside because the tension gradually relaxes at the shaft but must be kept tight at the outermost 20 inches of the film roll diameter.
In order to perform low-tension control on the blown film winder, Addex last year developed a high-end surface/gap winder called Superwind. This machine has a set of 13 AC servo motors with direct torque control - 6 per winding station, the remaining one for the input roller. One end of each winding shaft uses a large motor and the other end uses a small motor to drive the shaft. The dynamometers attached to the ends of the drum behind the drums and connected with fiber optic cables monitor the actual tension. Superwind controls the tension based on the torque data transmitted from all drive mechanisms, using only the dynamometer to align and verify the tension.
Addex president Rick von Kraus said that the system can provide more precise tension control, its accuracy is within 2% to 3%, and the accuracy of tension control is only 10% to 15%. He said that the dynamometer can accurately control the speed of the motor only if no slip occurs. If a slip occurs in a tension zone, it will affect the next action and cause a rumble.
Reifenhauser's high-speed UFA III winder adopts Rockwell Automation's Control Logix PLC to control the tension through the motor's sensor data and a fieldbus connected 3-7 driven rollers. Tension measures the deflection of the strain gage on the idler by the signal from the high speed dynamometer and then gives an electronic signal that is proportional to the actual tension.
Reifenhauser's surface winding machines use the servo drive of the shaft to generate mechanical pressure on the contact drum instead of using pneumatic or hydraulic pressure. This servo pressure can be as low as 50 N (11.25 lbs.) so that the viscous film can be wrapped in a pressure rather than a gap. The UFA III film winder can wind a film roll with a diameter of 59 inches.
A few years ago, Kiefel acquired the winding machine business of Wintech Winding Technology of Switzerland and Christian Maier GmbH of Germany. Kiefel merged two production lines into Kirion. The Kirion WM (Wintech Multi-purpose) multi-function surface/center/gap winder can control the tension to 40 N (9 lbs.) when winding very thin films. Its patented CLP2 (Constant Pressure) control and unique "bend resistant" carbon fiber roll prevent air entrapment.
Bigger, better, faster
Alpha Marathon, Inc., which manufactures blown film and cast film turret laminators, recently introduced a high-speed winder that winds a film with a transverse pleat that can be wound at 1,200 feet per minute, every 20 seconds. Roller automatic switching.
Black Clawson is developing a new "anvil" for the automatic switching of polyester film and OPP film. It uses a servo-driven cutter to punch the back roller. It is said that the stamping of the blunt edge on the back roller can cut brittleness. Polyester film does not crack. The servo drive accelerates the anvil support to move at the same speed as the film.
Davis-Standard installed high-speed cameras in its EPIC control system for the record-breaking Meridian film lapping machine to help optimize the high-speed movement of the reels. The model is now switching and stitching at 2,500 feet per minute.
Battenfeld Gloucester's 1002 DS (double shaft) winder winds an elastic cast film at speeds up to 2,000 feet per minute and can produce eight 20-inch wide rolls or six 30-inch wide rolls. Gloucester also offers a high speed double turret winder for coextruded blown film, using the first industrialized MDO unit. Prior to orientation, a 0.8-1 mil thick film was run at 225 feet per minute. After orientation, a film with a thickness of only 0.25-0.35 mils and a 4-fold increase in length was wound at 900 feet per minute.
Alpine manufactures surface and surface/center/gap reclaimers and is making its first gap rewinding machine with reverse winding capability, with a maximum winding speed of up to 1000 feet per minute.
Macro Eng