An apparatus and a method for flattening & profiling of wire

Abstract

The present invention discloses an apparatus and a method for a controlled flattening & profiling of the wire. The apparatus (100) includes of a plurality of mill units (M1, M2,…,Mn) through which a metal wire is passed. Each of the mill units (Mn) comprises at least one motor (20) and at least one motor drive (30).

Description

[0001] AN APPARATUS AND A METHOD FOR FLATTENING & PROFILING OF WIRE FIELD OF INVENTION:

[0002]

[0001] The present invention relates to a wire flattening and profiling mill. More particularly, the present invention relates an apparatus and a method for dynamically controlled flattening & profiling of a metal wire.

[0003] BACKGROUND & PRIOR ART:

[0004]

[0002] A metallic wire is flattened & profiled to get the desired shape and dimensions for various purposes or fields, for example electronic or electrical wirings, aerospace, automotive etc. The wire flattening & profiling includes decreasing the diameter of the wire, changing the wire cross-section or the shape of the wire, as per the need.

[0005]

[0003] Such a specific shape and dimensions for the metallic wire must be obtained without compromising the original quality of the metallic wire. Further, the product as a result of wire flattening & profiling must have a consistent cross-sectional profile and accurate dimensions. For this purpose, a special purpose machinery, called wire flattening & profiling mill, is used. Traditionally, this machinery mainly consists of rollers, called as flattening mill roller or Turk-head roller, having durable, wear resistant material and a wire tension control mechanism known as dancer or oscillator mechanism. During the flattening & profiling process, the wire is passed through multiple flattening & profiling heads, the dancer rollers are required to maintain the constant tension at various positions. With the assistance of the dancers and wire tension mechanism, the machinery synchronises movements & positions of the dancers as the material flows through them, and tries to maintain wire tension for a uniform thickness of the wire.

[0004] Inconsistent or incorrect wire tension may lead to wire breakage, or uneven thickness which may lead to compromised mechanical or electrical performance of the wire. Hence, maintaining constant wire tension between the rolling stands is critical for achieving uniform thickness, flatness, and high-quality surface finish which is a labored task. Several factors may contribute to prevent maintaining uniform wire tension. Each motor, even though seemingly exactly identical in construction, may have slightly different torque. Further during flattening process, the motors are designed to rotate at a same velocity. Yet in practice, the motors may have slightly different rotational velocity.

[0006]

[0005] To compensate the differential tension, sometimes an external wire loop is provided. Also, the attempt is made to keep the tension constant by increasing or reducing the wire length given by the previous mill.

[0007]

[0006] Proper operation of multi stand wire flattening & profiling mill requires a dancer to store the excess wire incur due to speed variation, elongation and slip etc. The state of the art systems use speed control systems combined with a dancer arm and dancer height utilizing load cells or swing rolls analog height sensors. These commonly used sensor-based schemes are invasive, expensive, require either special, or extra rolls, and add complexity to machine control to change in wire types and reduction needs.

[0008]

[0007] The present invention proposes an effective apparatus for controlled wire flattening & profiling process, which obviates the aforesaid problems associates with the existing systems, involving dancer arm that requires additional mechanical adjustments and bulk.

[0009] SUMMARY OF INVENTION:

[0010]

[0008] It is an object of the invention to provide an apparatus and a method that will provide a controlled flattening & profiling of the wire.

[0009] It is a primary object of the invention to provide an apparatus and a method to reduce the bulk and other deficiencies associated with the dancer arm while still providing precision and dynamic control for the flattening of the wire.

[0011]

[0010] Accordingly, the present invention discloses an apparatus for dynamically controlled flattening of a wire, without using a dancer arm or dancer assembly.

[0012] [Oil] In an embodiment, the said apparatus comprises a first mill unit functioning as a master unit which passes the metal wire to atleast one secondary mill unit; at least one secondary flattening / profiling head functioning as a slave unit and receiving the wire from the first flattening / profiling head; a sensing device and a control unit.

[0013]

[0012] In the same embodiment, the first mill unit comprises a motor and a motor drive, whereas the at least one secondary mill unit comprises at least one motor and at least one motor drive.

[0014]

[0013] In the same embodiment, the sensing device is configured to provide a feedback related to the motion of the motor to the control unit through the motor drive.

[0015]

[0014] In the same embodiment, the control unit has been assigned to perform following functions: measuring actual speeds of the motor drives based on the feedback from the sensing device; monitoring & computing in real-time difference in measured speeds; processing the difference in velocities through a closed loop control; generating torque reference command to the first mill unit; and regulating a current to the secondary mill units through thefirst mill unit, thereby synchronizing the first mill unit and subsequent mill units.

[0016]

[0015] In an another embodiment, the present invention discloses a method for dynamically controlled flattening and profiling of a wire.

[0017]

[0016] The said method comprises: commencing an operation of a first mill unit, wherein the mill unit is configured to function as a master unit and comprises of a motor & a motor drive; receiving the wire from the first mill unit by at least one secondary mill unit, wherein the secondary mill unit is configured to function as a slave unit and comprises of a motor & a motor drive; setting a speed of a motor drive, by a control unit, to a preset speed; measuring, by a control unit, actual speeds of the motor drives based on the feedback generated by a sensing device; monitoring & computing in real-time, by the control unit, difference in measured speeds; processing, by the control unit, the difference in velocities through a closed loop control; generating, by the control unit, a torque reference command to the flattening / profiling unit; and regulating, by the control unit, a current to the secondary mill units through the first mill unit.

[0018] BRIEF DESCRIPOTION OF DRAWINGS:

[0019]

[0017] Following drawings describe an embodiment of the present invention:

[0020] Figure 1 illustrates a simplified block diagram of the apparatus (100).

[0021] Figure 2 illustrates a schematic drawing of an exemplary embodiment of the apparatus (100) for controlled flattening & profiling of a metal wire.

[0022] Figure 3 illustrates interaction between the motors (20), the sensing device (60), and the motor drive (30).

[0023] Figure 4 represents a metal wire (W) passing through the mill unit (20,30). Figure 5 illustrates a block diagram representing a closed loop control that directs the method for controlled flattening & profiling of a metal wire.Figure 6 illustrates a graphical representation of the speeding cycle of the motor (20).

[0024] Figure 7 illustrates a relationship between torque producing current (Iq) and magnetizing current (Id).

[0025] Figure 8 represents a method of the present invention.

[0026] DESCRIPTION OF THE INVENTION:

[0027]

[0018] The present invention discloses apparatus for controlled flattening & profiling of a wire. Notably, the said apparatus cancels the need of the dancer assembly / dancer arm that is generally required in the wire thinning process. With the described and claimed apparatus, one may be able to achieve uniform wire thickness with a precision, and dynamic control.

[0028]

[0019] In the present specification, the terms “first mill unit” and “second mill unit” have been used. In these terms, “mill” has been used in a broader sense and indicates a profiling unit or flattening unit or a combination both. For the sake of clarification, the profiling unit provides desired shape to the metal wire, whereas the flattening unit assists in flattening the metal wire.

[0029]

[0020] The present invention may be comprehended by the figures 1-6 appended at the end of the specification. It may be realized that the figures demonstrate the schematics of the apparatus, which is described and claimed herein. By referring to the figures, a person skilled in art should not envisage the apparatus only to the figures, thereby restrict the scope of the invention to the demonstrated drawings.

[0030]

[0021] By referring to figures, Figure 1 represents a simplified block diagram of the apparatus (100), whereas Figure 2 provides schematic drawing of an exemplary embodiment of the apparatus (100). The apparatus (100) generally comprises a first mill unit Ml functioning as a master unit; at leastone secondary mill units (M2,... .Mn) functioning as a slave unit and receiving the wire W from the first mill unit Ml; a sensing device (60) and a control unit (10).

[0031]

[0022] In a preferred embodiment, the first mill unit Ml comprises a motor (21) and a motor drive (31), whereas the secondary mill units (M2,... .Mn) comprise at least one motor (22,23,24,25) and at least one motor drive (32,33,34,35). The sensing device (60) is configured to provide a feedback (EF1,EF2) related to the motion of the motor (22,23,24,25) to a control unit (10) through the motor drive (32,33,34,35).

[0032]

[0023] Figure 2 represents the apparatus (100) for controlled flattening & profiling of a wire in which the multiple slave units (secondary units) have been shown. The apparatus (100) includes of a plurality of mill unit (Ml, M2,...,Mn) through which the wire is passed. Each of the mill unit (Mn) comprises at least one motor (20) and at least one motor drive (30). Hence, the mill unit Ml comprises of the motor (21) and the motor drive (31); the mill unit M2 comprises of the motor (22) and the motor drive (32); and so on.

[0033]

[0024] In a preferred embodiment, the control unit (10) is configured to:

[0034] measure actual speeds (vl,v2) of the motor drives (31,32) based on the feedback (EF) from the sensing device (60);

[0035] monitor & compute in real-time difference Av in measured speeds (vl,v2);

[0036] process the difference in velocities Av through a closed loop control; generate torque reference command (TR) to the first mill unit Ml; and regulate a current to the secondary mill units (32) through the first mill unit Ml, thereby synchronising the first mill unit Ml and subsequent mill units M2, ...Mn.

[0025] In a preferred embodiment, the control unit (10) may be a machine controller. Further in a preferred embodiment, the motors (21,..., 25) may be AC motors and the motor drive (31,... ,35) may be variable frequency drives (VFDs). Also in the same preferred embodiment, the sensing device (60) may be an encoder.

[0037]

[0026] The mill unit Ml functions as a master unit, configured to be controlled through the control unit (10). This ensures a speed fluctuation in the first mill unit Ml upto 0.1%. The second mill unit M2 is configured to operate in a torque mode and serves as a slave unit to the first mill unit Ml. In the torque mode, the second mill unit M2 is provided with an automated speed control mechanism by the control unit (30), based on the feedback from the sensing device through the motor. Thus the material elongation in the first mill unit Ml is absorbed by the second mill unit M2 through a swift change in the motor speed. The correction in the motor speed by the control unit (10) takes place in a predefined time, which is usually at a 2 ms. Such a corrective action eliminates the need of the dancers, which have been described in the “ Background & Prior Art” . The mill unit subsequent to the mill unit M2 act as slave units to the second mill unit M2. The said subsequent mill unit M3, M4, ... , Mn-1 receive speed controlling instructions by the control unit (10), which ensures smooth tension between the adjacent units.

[0038]

[0027] Figure 5 shows the operation of the control unit (10). The control unit (10) receives external instructions (comm) in a speed controller (11) to set an initial speed of the motor (20), which is relayed by the motor drive (30). The sensing device (60), preferably an encoder, provides a feedback related to the motor (20). The evaluator circuit (12) provides the signal after the evaluation to the speed controller (11), which in turn provides instructions to a current controller (14) to adjust the motor (20). It may benoted that the control unit (10) is a cyclic control unit, with short cycle time in order to detect correct uncontrol.

[0039]

[0028] Figure 6 illustrates a graphical representation of the velocity profile of the motor (20), S-Curved Trapezoid Velocity profile gradually changes the acceleration / deceleration. Such gradual changes help in reducing mechanical shock, (jerk in motor, gearbox, couplings and further help smooth torque buildup, tension prediction, and energy efficiency.

[0040]

[0029] Figure 7 illustrates a relationship between torque producing current (Iq) and magnetizing current (Id). Fully Closed Loop motor control method employs a vector algorithm to determine output voltage based on encoder feedback. Encoder feedback paired with the vector control method allows for 200% motor starting torque at 0 rpm. The encoder feedback allows for the highest speed response, over 50 Hz, and also the highest speed control range 1:1500. In addition to these high performance operating specification, the FCL method also has the ability to run the motor in precise torque control mode. Torque control mode allows the VFD to directly control motor torque instead of motor speed. This is necessary for wire flattening & profiling mill where torque takes priority over speed and in Re-Winder.

[0041]

[0030] In the present invention, a constant torque is generated through the control unit (10), which ensures smooth acceleration as well as deceleration of the motors, without causing any jerk. It further carefully and continuously senses line speed increase incurred due to wire flattening & profiling process and automatically compensates the line speed to maintain the line tension at rate of 2mSec.

[0042]

[0031] Figure 8 describes the working of the apparatus (100). After the commencement of the operation of the apparatus, the motor speed vl of themaster unit is set to a predetermined speed (step 103) by the control unit (10). If the presence of wire is detected by a sensor present therein, the tension in the motor (32) of the slave unit is adjusted by the control unit (10), as shown in step 104 and step 106. This cyclic process goes on till the stop command is generated (step 107).

[0043]

[0032] The present invention further discloses a method for dynamically controlled flattening & profiling of a wire (W), which comprises:

[0044] (a) commencing an operation of a first mill unit Ml, wherein the mill unit Ml is configured to function as a master unit and comprises of a motor 21 & a motor drive 31 ;

[0045] (b) receiving the wire W from the first mill unit Ml by at least one secondary mill unit (M2,....Mn), wherein the secondary mill unit (M2,....Mn) are configured to function as a slave unit and comprise of a motor 22 & a motor drive 32;

[0046] (c) setting a speed vl of a motor drive 31, by a control unit 10, to a preset speed;

[0047] (d) measuring, by a control unit (10), actual speeds (vl,v2) of the motor drives (31,32) based on the feedback (EF) generated by a sensing device (60);

[0048] (e) monitoring & computing in real-time, by the control unit (10), difference Av in measured speeds (vl,v2);

[0049] (f) processing, by the control unit (10), the difference in velocities Av through a closed loop control;

[0050] (g) generating, by the control unit (10), a torque reference command (TR) to the first profiling unit Ml; and

[0051] (h) regulating, by the control unit (10), a current to the secondary mill units (32) through the first mill unit Ml .

[0052]

[0033] Advantages:The present invention provides inertia compensation during dynamic speed changes as well as friction loss compensation, under all conditions in all elements of the drive and load.

[0053] The present invention provides predictable tension changes at the given speed.

[0054] The present invention is configured to adjust to various material and reduction

Claims

We claim,1. An apparatus (100) for dynamically controlled flattening & profiling of a wire (W) comprises:a first mill unit Ml functioning as a master unit comprising a motor (21) and a motor drive (31);at least one secondary mill unit (M2,....Mn) functioning as a slave unit and receiving the wire W from the first mill unit Ml, wherein the secondary mill unit (M2,....Mn) comprise at least one motor (22,23,24,25) and at least one motor drive (32,33,34,35);a sensing device (60) configured to provide a feedback (EF1,EF2) related to the motion of the motor (22,23,24,25) to a control unit (10) through the motor drive (32,33,34,35); anda control unit (10) configured to(i) measure actual speeds (vl,v2) of the motor drives (31,32) based on the feedback (EF) from the sensing device (60); (ii) monitor & compute in real-time difference Av in measured speeds (vl,v2);(iii) process the difference in velocities Av through a closed loop control;(iv) generate torque reference command (TR) to the first mill unit Ml; and(v) regulate a current to the secondary mill units (32) through the first mill unit Ml, thereby synchronising the first mill unit Ml and subsequent mill units M2, ... Mn.

2. The apparatus (100) as claimed in claim 1, wherein the sensing device (60) is an encoder.

3. The apparatus (100) as claimed in claim 1, wherein the closed loop control executed by the control unit (10) is a Pl-control loop.

4. The apparatus (100) as claimed in claim 1, wherein the control unit (10) is operable through a user interface device (40).

5. A method for dynamically controlled flattening of a wire (W) comprises:(a) commencing an operation of a first mill unit Ml, wherein the mill unit Ml is configured to function as a master unit and comprises of a motor 21 & a motor drive 31 ;(b) receiving the wire W from the first mill unit Ml by at least one secondary mill units (M2,... .Mn), wherein the secondary mill units (M2,....Mn) are configured to function as a slave unit and comprise of a motor 22 & a motor drive 32;(c) setting a speed vl of a motor drive 31, by a control unit 10, to a preset speed;(d) measuring, by a control unit (10), actual speeds (vl,v2) of the motor drives (31,32) based on the feedback (EF) generated by a sensing device (60);(e) monitoring & computing in real-time, by the control unit (10), difference Av in measured speeds (vl,v2);(f) processing, by the control unit (10), the difference in velocities Av through a closed loop control;(g) generating, by the control unit (10), a torque reference command (TR) to the first mill unit Ml; and(h) regulating, by the control unit (10), a current to the mill units (32) through the first mill unit Ml .

6. The method as claimed in claim 5, wherein the closed loop control executed by the control unit (10) is a Pl-control loop.

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