An automatic dereeler includes a rocker arm that is movable between various positions to indicate the relative tension on a continuously supplied material. A sensor detects the rocker arm position which is transmitted to a controller. The controller actively controls a motor to either increase or decrease the resistive torque on a rotating axle that carries the continuous material.

BACKGROUND

Many manufacturing processes require the input of continuous materials such as coils, straps, etc. These materials are typically supplied in spools that are paid out during fabrication of a product. For example, transformer coil making machines require a continuous feed of coil material, wherein numerous turns of the coil material are wrapped onto a core. To prevent jamming and otherwise improve machine performance, it is advantageous to supply the coil material at a relatively constant tension.

Thus there is a need in the art for a dereeler having automated control of tension to provide relatively constant tension within predefined ranges.

SUMMARY OF THE INVENTION

According to one aspect of the present invention an automated dereeler is provided for feeding spools of continuous material into a machine. The dereeler includes a housing rotatably carrying an axle which has a first end. The axle carries the spool of continuous material at the first end. A motor is secured proximate to the housing and is mechanically interconnected to the axle. A brake is secured to the housing and is positioned to provide a constant braking torque to the axle. A dancer arm is pivotally secured to the housing and is movable between a first position and a second position. The dancer arm includes a spindle around which the continuous material is fed into the machine. A spring assembly has a first end and a second end, the first end being secured to the housing and the second end being secured to the dancer arm. The spring assembly biases the dancer arm toward the first dancer arm position. A sensor is adapted to monitor the position of the dancer arm. A controller controls the motor and is in communication with the sensor. The controller causes the motor to resist rotation of the axle when the dancer arm is in the first dancer arm position. The controller causes the motor to aid rotation of the axle when the dancer arm is in the second dancer arm position.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT(S)

With reference now toFIGS. 1-4a dereeler10is shown and generally indicated by the numeral10. Dereeler10includes a frame12having a pair of opposed, vertically extending sections14in the form of plates. Vertically extending sections14are spaced by a bottom laterally extending section16and a top laterally extending section18. Bottom laterally extending section16extends substantially the entire length of vertically extending sections14. Top laterally extending section18extends less than the entire length of the vertically extending sections14. Two feet20are secured to the bottom of bottom laterally extending section16and vertically extending sections14and extend laterally for improved frame stability.

It should be appreciated that any frame or other structural element may be made of any metal or other material of suitable strength. The frame and/or structural elements may be of any form including, plates, tubes, hollow rectangular, corrugated, etc. Though the components of the frame are shown as welded in the figures, it should be appreciated that other means of attachment may be utilized, such as, for example treaded fasteners or riveting. Still further, frame12may be cast and one or more components may be formed as a single unified component.

Frame12includes an arm stop22extending upwardly at an angle from a first edge24of vertically extending sections14. Arm stop22includes two connecting sections26attached to first edge24. Connecting sections support a stop plate28that extends between connecting sections26and includes a stop surface30. As will be hereinafter described in greater detail, stop surface30is positioned to engage a dancer arm32.

A first and second extending portion34and36respectively extend upwardly from an outer vertically extending surface38of top laterally extending section18. First and second extending portions34and36each include an axially aligned hole40. A shaft block42is positioned between first and second extending portions34and36. Shaft block42includes a pair of outwardly extending circular projections44that are received in holes40such that shaft block42is rotatable about the axis formed by holes40. Shaft block42further includes a central aperture46which is adapted to slidably receive a cylindrical spring carrier48.

Dancer arm32is generally L-shaped and is adapted to carry a spindle50at a first end52. To that end, a cylindrical spindle shaft54extends from first end52and rotatably carries spindle50. Spindle shaft52further carries a U-shaped guide56which does not rotate and is positioned around spindle50. Dancer arm32is carried by, and rotatable about, a cylindrical arm shaft60. Arm shaft60extends between vertically extending sections14and is received within bores62. Dancer arm32includes a second end58having bores64that receive arm shaft60. In this manner, dancer arm32may pivot about arm shaft60. The pivoting motion is, however, limited. With reference toFIG. 3, clockwise rotation is bounded by arm stop22. Likewise, counterclockwise movement is bounded by a restraining bar66that extends between vertically extending sections14.

Dancer arm32is biased toward arm stop22by a spring assembly68. Spring assembly68includes the aforementioned spring carrier48which carries a spring70positioned axially centered on the cylindrical spring carrier48. According to one embodiment, spring70is a die spring. Spring70is maintained in compression between shaft block42and a raised catch72. At the end of spring carrier48opposed from shaft block42is a U-shaped member74having a pair of opposed holes76. Dancer arm32includes a pair of raised flanges78having a pair of opposed holes80. A pin82is secured within holes76and holes80to pivotally secure spring assembly68to dancer arm32. As should be evident, spring70biases dancer arm32toward arm stop22. However, if an opposing force overcomes the spring bias, rotation of dancer arm32is possible because spring carrier48may slide through central aperture46.

A spool axle84extends through bores86in vertically extending sections14. Spool axle84extends from both sides of frame12. A first end is rotationally coupled to a gearbox88. Gear box88is in turn rotationally coupled to a motor90. In this manner, motor90imparts a torque on spool axle84to cause rotation and/or resist rotation (i.e. a braking force). Motor90is driven by a variable frequency drive (hereinafter VFD) that is responsive to signals from a controller. The controller may be any device capable of receiving sensory signals and outputting control commands. According to one embodiment, the controller is a programmable logic controller (hereinafter PLC). An exemplary PLC may include an Omron PLC using DeviceNet communication and an analog signal. The PLC may be used to control just dereeler10or may control the entire manufacturing machine in addition to dereeler10. In still other embodiments, the PLC is integrated with or communicates with a separate PLC controlling one or more additional manufacturing operations.

The end of spool axle84opposed from gear box88carries a spool89(seeFIG. 5) of wire, cable, or other continuous material used in a manufacturing process. A flange92is provided to rotationally couple the spool to the spool axle84. In this manner, axle84and the spool rotate together.

A brake94(shown inFIG. 4) is secured to frame12and is positioned to apply a continuous braking force to spool axle84. Though any number of brakes may be employed, it is advantageous to use a brake that applies substantially constant braking torque, efficiently dissipates heat and has a relatively high contact surface area. According to the present embodiment, an air pressure operated tensioning type brake is particularly advantageous. For example, a Nexen brand shaft mounted friction brake provides acceptable shaft braking performance.

A linear transducer96(shown inFIG. 3) is secured at one end to second extending portion36and at the other end to a tab98on dancer arm32. Thus, it can be seen that linear transducer96outputs a continuous or periodic signal indicative of the angular position of dancer arm32. Signal from the linear transducer96is output to the controller (PLC), which in-turn transmits command signals to the VFD.

As is known in the art, continuous material100(seeFIG. 5) is drawn or pulled into a manufacturing machine. Thus, dereeler10advantageously provides a substantially constant resistance (i.e. tension) to the drawing in of the continuous material. Constant and well regulated tension prevents jamming and/or machine failure. As should be evident, the relative position of dancer arm32is dependent upon the tension on the continuous material. The greater the tension, the more the spring pressure is overcome and the dancer arm32will move forward.

Dereeler10is operable in a torque control mode. In the torque control mode, brake94is set at a constant pressure (i.e. constant torque). In this mode, if the dancer arm32is in a first, resting position, contacting arm stop22(seeFIG. 5a), a reverse or braking torque is applied by motor90. As should be appreciated, linear transducer96monitors the dancer arm position, transmits the position signal to the PLC, which in turn transmits the motor control commands to the VFD. When dancer arm32is in the first, resting position, the tension on the continuous material is relatively light, and not great enough to overcome the spring tension. This may represent a situation wherein the manufacturing machine is idle and not drawing any continuous material.

If dancer arm32is in a second, fully forward position (seeFIG. 5c), resting against restraining bar66, a forward rotating torque is applied by motor90. Thus, the range of torques provided by the motor90is: at first, resting position, a 100% CCW torque (i.e. resisting the removal of continuous material from the spool), at second, forward position, a 100% CW torque (i.e. promoting removal of continuous material from the spool), at a third, center or optimal position, no CW or CCW torque is applied by motor90. Thus, as material is pulled from the dereeler10, the dancer arm32moves forward and motor reverse torque decreases. As the dancer arm32continues forward, reverse torque will continuously decrease until passing the third position, wherein motor torque now switches to forward torque (i.e. promoting rotation of spool89)

A second, auxiliary mode is contemplated according to the present invention. Occasionally, an operator might overshoot the amount of continuous material needed, might need to make a repair or may need to change material. In such an instance, the motor90may be commanded to increase reverse torque enough (i.e. a torque greater than the braking torque supplied by brake94) to pull the continuous back and rewind it on spool89.

Thus, by way of an example, an operator may set the air pressure to 20 psi for the brake94. This in turn results in a constant braking torque applied to spool axle84. As a manufacturing machine draws continuous material (e.g. wire) from dereeler10, dancer arm32moves forward. This is because rotation of spool axle84is prevented by both motor90and brake94. As dancer arm32moves forward, reverse torque from motor90decreases. At some point in the forward movement of dancer arm32, the force of the manufacturing machine pulling on the wire overcomes the combined resistive torque of the motor90and brake94. This in turn allows material feed to the machine. In response to PLC commands, the VFD drives the motor90to provide scaled forward or reverse torque to the motor/gearbox as needed. The PLC reads the position of the transducer96and sends the appropriate signal levels.

As should be appreciated, the resistance of the dereeler is determined by summing the brake resistance with the motor/gearbox resistance, as controlled by the VFD. Thus, when the dancer arm32is in the first, resting position, the dereeler resistance is the brake resistance plus 100% motor/gearbox resistance torque. If the dancer arm32is in the third, neutral position, the dereeler resistance is only the brake resistance. And if the dancer arm32is in the second, forward position, the resistance is the brake resistance minus 100% motor/gearbox resistance. The motor/gearbox torque ramps up between 0 and 100% as the dancer arm32moves thus enabling fast closed loop control with high precision. It should be appreciated, that even when the dancer arm32is in the second, forward position, the resistance from brake90is greater than the torque provided by the motor/gearbox. In this manner, the continuous material is always under tension. The tension of the continuous material is effectively increase or decreased and regulated through the linear transducer, PLC and the VFD.

By way of a specific example, brake90is set at 20 psi and creates enough friction such that 35 ft-lbs of force is required to rotate spool axle84and the motor/gearbox is capable of 18 ft-lbs of force at 100%. If dancer arm32is positioned in the first, resting position, 53 ft-lbs of force is required to rotate the spool axle84. As the arm moves forward, that force decreases in direct correlation to the angular position of dancer arm32. If the arm is in the second, forward position, the required to rotate the spool axle is 17 ft-lbs.

As will be appreciated by one of ordinary skill in the art, the controlling mechanisms of the present invention may be embodied as or take the form of the method and system previously described, as well as of a computer readable medium having computer-readable instructions stored thereon which, when executed by a processor, carry out the operations of the present inventions as previously described and defined in the corresponding appended claims. The computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program instruction for use by or in connection with an instruction execution system, apparatus, or device and may by way of example but without limitation, be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium or other suitable medium upon which the program is printed. More specific examples (a non-exhaustive list) of the computer-readable medium would include: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), DVD, an optical storage device, a transmission media such as those supporting the Internet or an intranet, or a magnetic storage device. Computer program code or instructions for carrying out operations of the present invention may be written in any suitable programming language provided it allows achieving the previously described technical results.

It is to be understood that the description of the foregoing exemplary embodiment(s) is (are) intended to be only illustrative, rather than exhaustive, of the present invention. Those of ordinary skill will be able to make certain additions, deletions, and/or modifications to the embodiment(s) of the disclosed subject matter without departing from the spirit of the invention or its scope, as defined by the appended claims.