Abstract:
A continuous winding machine uses embedded controllers to monitor and control the winding settings in maximum speed applications. Power is supplied to the embedded controllers from a main power source through a rotary transformer. The control system can be operated either through wired connections to a local computer or processor, or through a wireless system, or a combination of both, depending on the specific application. The machine uses a high speed, closed loop tensioning system that includes the filament supply spools and the mandrel supply and takeup spools. The control system menu includes the various winding operations useful to each user. The control system menu can be accessed remotely via computer, or by telephone.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to tension control systems, and more particularly is an improved tension control mechanism for a continuous winding machine that utilizes wireless or wired embedded closed loop feedback systems. 
     2. Description of the Prior Art 
     Coil winding technology has existed for quite some time in various fields. For example, the textile industry has long used winding methods to spool threads and yarns. Some examples of references in this area are the “Method and Apparatus for Winding a Thread on a Bobbin at a High Winding Speed” by Hori, et al., U.S. Pat. No. 4,059,239, issued Nov. 22, 1977; “Winding Apparatus” by Davies, U.S. Pat. No. 4,538,772, issued Sep. 3, 1985; and the “Operation Controlling Method for Textile Machine” of Matsui, et al., U.S. Pat. No. 4,984,789, issued Jan. 15, 1991. Another large subset of winding machines is directed to the art of coil winding for electric motor armatures. See, e.g., “Wire Tensioner for a Wire Handling Machine” by Hongo, et al., U.S. Pat. No. 5,080,295, issued Jan. 14, 1992. 
     A newer area for the application of winding technology is in the medical devices field. Catheters and stents are constructed by wrapping fine wires around a central mandrel. Current technology catheters and stents require the use of very fine wire filaments wrapped around proportionally small mandrels with winding angles that must be very accurately controlled. The very small diameters of the elements involved and the tight tolerances required make it difficult for current art equipment to construct the coils to the required specifications and without breakage. 
     One disadvantage of the prior art devices is that they typically use only one-way feed friction control, which produces filament tension that varies with feed rate. While this methodology is acceptable for applications using relatively large filament sizes, for the smaller filament sizes required in, for example, current art medical devices, the forces involved in commonly used feed rate control techniques are not acceptable The force necessary to control the feed rate is greater than the filament can withstand, so that breakage occurs. 
     Another disadvantage of the prior art devices is that the non-distributed control systems are too large and require too many control wires to enable an independent filament dispenser to spin around a mandrel, as continuous winding requires. The communication required to process information from the sensors to drive the necessary control motors in the machines controlling computer cannot be interrupted. 
     A further disadvantage of prior art systems that use control systems separate from the filament dispensing control is that multiple slip rings are required to operate with the supply spools rotating around the mandrel. The slip rings wear out quickly, and create debris that is unacceptable in cleanroom environments. 
     Accordingly, it is an object of the present invention to provide a continuous winding machine with embedded, closed loop tension control to enable production with much finer filament sizes and to tighter tolerances than is possible in prior art systems. 
     It is another object of the present invention to provide a winding machine that can be operated by both wireless data and wired data control systems. 
     Yet another object of the present invention is to provide a system that can be programmed for multiple winding parameters, and to provide a system in which the programming can be accomplished remotely. 
     SUMMARY OF THE INVENTION 
     The present invention is a continuous winding machine. For maximum speed and control applications, the machine uses an embedded controller to monitor the dispensing of wind filament. The embedded controllers can be operated either through wired connections to a local PLC (programmable logic controller), or through a wireless system, or a combination of both, depending on the specific application. The use of embedded controllers greatly reduces the amount of wiring used in the machine, inasmuch as the wired connections are used only to transfer data between the embedded controllers and the PLC. 
     The machine uses multiple closed loop tensioning systems that include the filament supply spools and the mandrel supply spool and takeup spool. The control system menu includes the various winding operations useful to each user. The control system menu can be accessed locally through a touch screen or remotely via computer, or by telephone. 
     An advantage of the present invention is that the machine can wind to tolerances much tighter than those of current art machines. 
     Another advantage of the present invention is that the wind angle can be controlled to vary the preload, or stiffness, of the coil product. 
     Yet another advantage of the present invention is that it can more easily handle thin filaments. 
     A still further advantage of the present invention is that the programming control can be accomplished by remote access means. 
     Still another advantage of the present invention is that the machine provides automatic counterbalancing of the winding module. 
     These and other objects and advantages of the present invention will become apparent to those skilled in the art in view of the description of the best presently known mode of carrying out the invention as described herein and as illustrated in the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of the continuous winding machine of the present invention. 
         FIG. 2  is a front view of the mandrel feed and winding mechanisms. 
         FIG. 3  is a front view of the winding mechanisms and the mandrel takeup assembly with the winding mechanism shown in greater detail. 
         FIG. 4  is a top plan view showing the mandrel supply, mandrel takeup, and winding mechanisms in conjunction with the machine vision used for angle sensing and pitch control. 
         FIG. 5  is a right side view of the winding module showing the wire (filament) feed spools and their respective load cells and dancers, and the counterbalance mechanisms. 
         FIG. 6  is a left side view showing the embedded controllers of the filament spools, tensioner, and balancer. 
         FIG. 7  is a block diagram of the control system for the winding machine utilizing multiple closed loop feedback systems. 
         FIG. 8  is a block diagram showing the embedded controllers in greater detail. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is a continuous winding machine  10 . The mechanical structure of the winding machine  10  can best be understood with reference to  FIGS. 1-6 . The winding machine  10  is installed on a movable mounting table  12 . A touchscreen  14  enables the user to easily program the various operations performed by the machine  10  by choosing a pre-installed manufacturing recipe, and/or creating modified recipe settings. 
     The central element of the product being manufactured by the winding operation is a mandrel  16 , the core of the wound product. The mandrel  16  is fed into the winding machine  10  from a mandrel supply assembly  18 . The mandrel  16  is fed off a mandrel supply spool  20 , across a first dancer  22 , and then across a first load cell  24  around the pitch drive  48  and over a second load cell  32  associated with a mandrel takeup spool  28 . 
     The mandrel  16  is then fed into the cylindrical housing of the winding module  26 . After the mandrel  16  has passed through the winding module  26 , the mandrel  16  is collected on the mandrel takeup spool  28  as the finished product. The mandrel takeup spool  28  has an associated second dancer  30  and the second load cell  32 . The second load cell  32  is mounted to the left of the winding module  26 . The mandrel takeup spool  28  and the second dancer  30  are contained in a sliding takeup assembly  34 . The takeup assembly  34  is mounted on slide tracks so that the assembly  34  can be easily moved to facilitate loading of the machine. 
     The winding module  26  is shown in detail in  FIG. 5 . In the embodiment illustrated, a first filament spool  36  and a second filament spool  38  are utilized. While any number of filament feed spools could be chosen, in the preferred embodiment, two spools  36 ,  38  are utilized. Because the winding module  26  spins at high speed during the winding operation, a pair of spools is chosen so that the module  26  can be more easily balanced. A third dancer  40  and a third load cell  42  are associated with the first filament spool  36 . Similarly, a fourth dancer  44  and a fourth load cell  46  are associated with the second filament spool  38 . 
     A counterbalance mechanism  47 , a device comprising a movable weight, is associated with each filament spool  36 ,  38 , and is controlled by the respective embedded controller  62 . The counterbalance mechanisms keep the winding module  26  in balance as material is used off the filament supply spools  36 ,  38 . A vibration sensor, accelerometer  60  in communication with the PLC, detects any vibration that is present during operation of the machine  10 . When any vibration is detected by the accelerometer  60 , the PLC commands the embedded controller to adjust the counterbalance mechanism  47  to correct the weight distribution to eliminate the vibration. 
     Machine vision using an angle sense camera  66  is used to monitor the filament winding angle on the mandrel  16 . To enable the machine vision that is used to detect winding angle, the camera  66  is installed with a backlight  68  in a position that allows the camera  66  to monitor the winding angle of the filaments on the mandrel  16 . The winding angle information gathered via machine vision is displayed on a vision monitor  50 , and is sent to the PLC, enabling the PLC system to adjust the electronic gearing to control winding pitch. 
     The winding pitch of the filaments onto the mandrel  16  is defined by the feed rate of the mandrel  16  per revolution of the winding module  26 , which is controlled by the relative speeds of a pitch drive servo motor  48  and a rotation servo motor  56 . A rotation sensor  58  triggers the angle sense camera  66  to record the winding angle while the filaments are in a viewable location. The PLC system uses that angle information to define a gearing ratio between the pitch drive servo motor  48  and the rotation servo motor  56 . The pitch drive servo motor  48  drives the mandrel supply spool  18 , and the rotation servo motor  56  rotates the winding module  26 . When the proper gearing ratio is established, the pitch drive servo motor  48  advances the mandrel  16  at a feed rate that is synched with the speed at which the rotation servo motor  56  rotates the winding module  26  so as to obtain the desired winding pitch. 
     In order to reduce wiring in the machine, power is supplied to moving parts via an oscillator and a transformer with a stationary primary coil and a movable secondary coil. As can be seen in  FIG. 3  and, in the preferred embodiment a rotary transformer  52  and a transformer oscillator  53  are used to form the interface between the main DC power supply of the machine and a rotating power supply  54  that is included with each rotating mechanism. 
     Operation of the control system of the winding machine  10  can best be understood with reference to  FIG. 7 , a block diagram of the overall control system of the winding machine  10 , and to  FIG. 8 , a more detailed block diagram of the closed loop servo control systems. The control system is a key element that enables the superior tension and angle control produced by the winding machine  10 . 
     Tension of the wires and mandrel used in the machine is controlled to 0.1 gm. Due to the small sizes of wires used in the winding machine—filaments as small as 0.0004 in. diameter with a 0.001 in. diameter mandrel—the tension control is critical to avoid breakage. 
     Because pitch tolerances of ±0.0001 in. are not uncommon in the devices produced by the winding machine  10  of the present invention, the control system must use an electronic gearing servo system for fast and precise control of the filament and mandrel feeds. The angle sense camera  66  senses the wire angle to 0.01° and controls the wire angle to 0.05°. To adjust preload, or stiffness, of the wound coil product, a back-angle makes the pitch closed, (closed pitch meaning the pitch is equal to the filament diameter so that there is no spacing between wraps), thereby making the coil stiffer. 
     Each of the wire dispensing elements of the winding machine  10 , the mandrel supply spool  20 , the mandrel takeup spool  28 , each of the filament spools  36  &amp;  38 , and the winding module  26  itself, all employ closed loop feedback systems to control their motion. Any number of filament spools can be utilized in the machine. In the preferred embodiment, two spools  36  &amp;  38  are used due to balancing considerations. For illustrative purposes,  FIG. 7  shows the control elements for the mandrel spools and for two filament spools. 
     The PLC system controls the overall operation of the winding machine  10 . Multiple winding settings are stored as recipes in the PLC, and are accessed by the user through the touch screen. It should also be noted that access to the PLC can be provided by many known data transmission means, such as wireless, or even telephone access. For wireless communications, a stationary antenna  64  is included in the winding machine  10  (shown in  FIG. 2 ). In the preferred embodiment, the antenna  64  enables the PLC to communicate with the two embedded controllers that spin with the winding module  26 . 
     The user can program and store settings for as many combinations of winding pitch, distance, tension, angle, and speed as are desired. Because of the continuous nature of the winding machine  10 , the length of the product is limited only by the size of the mandrel and filament supply spools  16 ,  36 ,  38 . Multiple products can be produced without interrupting the operation of the machine, most readily by programming visible separation points between the various windings on the continuous mandrel. 
     Each wire dispensing element in the winding machine  10  has an associated dancer to apply tension and to detect slack, or the free length between the spool and its associated guide pulley. Each dancer has a position sensor and a servo-adjusted spring to apply tension to the wire. Each wire dispensing element also has an associated element to detect tension, a load cell in the preferred embodiment. Many types of position, tension, and motion sensors known in the art may be utilized while retaining the teachings of the present invention. In the preferred embodiment, optical interrupt, Hall Effect sensors, and load cells are utilized most often. 
     The information from the sensors associated with the pitch drive servo motor  48  and the rotation servo motor  56  is transmitted to the PLC. The PLC uses that information to generate the necessary angle control (using data from angle sense camera  66 ) and electronic gearing speeds for the pitch drive servo motor  48  and for the rotation servo motor  56  so that the desired winding characteristics are created in the product. The data fed from the PLC to the pitch drive servo motor  48  and the rotation servo motor  56  causes those elements to make the necessary adjustments—servo motor advance, pitch drive advance, etc.—for the desired pitch of the product. 
     The winding machine  10  operates to very tight tolerances as described in preceding sections above. In order to maintain those tolerances, the winding machine  10  must communicate required motion control information to the wire dispensing elements in microsecond time frames. Ordinary control systems that use control instructions from a PLC through common communication means are simply too large and require too may wires. An optimal control system must use a minimal number of wires while maintaining high speed communication. To do this, the continuous winding machine  10  of the present invention utilizes embedded controllers  62  for the mandrel supply  18  and takeup  28  spools, and for the high speed (in excess of 1500 rpm) rotating filament supply spools  36 ,  38 . The embedded controllers  62  are integral to the wire dispensing elements with which they are associated. Since the embedded controllers  62  are mounted directly onto the elements they control, the embedded controllers  62  associated with the filament spools  36 ,  38  rotate with the winding module  26 . 
     Each of the wire dispensing elements—the mandrel supply spool  20 , the mandrel takeup spool  28 , and the filament supply spools  36 ,  38 —has an associated dancer and load cell, each with sensors that provide position information to a closed loop tension control unit. A first servo loop in each tension control unit maintains slack in response to the dancer position readings. A second servo loop in each tension control unit maintains tension in response to the tension readings from the load cells. All the circuitry required for the slack and tension control for each closed loop tension control unit, and therefore each wire dispensing element, is self-contained in an associated embedded controller  62 . The circuitry required for the operation of the wire dispensing elements is therefore local to each dispensing unit, significantly reducing the number of wires required and the communication time for the feedback loops. 
     Each of the embedded controllers  62  is in communication with the PLC, but only to receive initial program instructions from the winding recipes stored in the PLC. The embedded controllers  62  do send operating information to the PLC, but the information is for display purposes and fault monitoring only, enabling the operator, through the PLC, to track the operation of the machine. The only interaction the PLC has with the tension and slack servo loops of the tension control units is if the data received from the tension control loops show tension or slack measurements outside acceptable operating limits. In this case, the winding machine  10  is shut down to correct whatever is causing the operating error. This situation very rarely occurs. 
     As shown in  FIG. 7 , the communication between the embedded controllers  62  and the PLC can be either wireless, as in the case of the filament spools  36 ,  38 , or hard wired as with the mandrel supply and takeup spools  20 ,  28 . 
     The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the restrictions of the appended claims.