Wire processing machine including a conductor monitor device

An illustrative wire processing machine includes at least one blade configured for at least one of cutting a conductor or at least piercing an insulation layer on the conductor. At least one gripper assembly includes a gripper configured to at least temporarily grasp a portion of a conductor during a wire processing operation. A generator, which is part of the gripper assembly, is configured to radiate a field toward a conductor. The gripper assembly also includes a detector that is configured to detect at least some of the field propagated along the conductor. A processor is configured to determine when a change in the propagated field detected by the detector indicates contact between a conductor and the blade.

BACKGROUND

Electrical conductors are used in a variety of situations, such as in vehicle systems, for providing power to electrically powered components and communicating information among components. Most automated assembly techniques that involve electrical conductors include cutting the wires to a desired length and stripping insulation from the ends of the wire. The exposed wire ends are eventually connected in a manner that facilitates the desired power or communication connections.

One of the difficulties associated with wire processing equipment is that it may not be possible to avoid improperly cut or otherwise damaged wires. For example, the insulation stripping blades may penetrate too deeply through the insulation and contact the wire. It is also possible that the wire is not centered within the insulation at the location where the stripping blades contact the insulation and the blades also contact the wire. It is also possible, for example, that the segment of wire that is introduced to the stripping device has a configuration that results in an unexpected alignment between the stripping blades and the wire so that the stripping blades contact the wire when the insulation is cut and stripped from the wire end. Contact between an insulation stripping blade and a wire during the stripping operation typically results in an undesirably cut or damaged wire. If the integrity of a wire end is compromised the eventual connection that is supposed to be made through that wire may be faulty.

Detecting damage to the wires during the stripping process has proven difficult for several reasons. For example machine throughput may be at a very high rate which requires a very fast response from a detection device and reliable detection may not be achievable without slowing down the wire processing machine. Additionally, the way in which wires are manipulated during the cutting and stripping process makes it difficult or impractical to attempt to establish an electrically conductive physical connection with the wire for monitoring purposes.

One attempt at detecting when a wire may have been damaged while insulation was stripped from the wire is described in the United States Published Patent Application No. US2013/0125710. That document suggests using a wired connection between the stripping blades and a control board and measuring an impedance of the stripping blades. If there is contact between the stripping blades and the conductive wire, the impedance of the conductive wire is effectively added to that of the stripping blades. The increased impedance is described as being detectable for purposes of identifying when the stripping blades contact the wire. One drawback associated with that approach is that it requires a specially designed stripping device or modification of a stripping device to include the electrically conductive connection between the stripping blades and the control board.

With the increasing amount of technology being included in vehicles, for example, there is an increasing need for wiring and more reliable connections. Current trends also include a desire to reduce the size (i.e., diameter) of the wires. It is becoming increasingly important to ensure that damaged or improperly cut wires are identified to avoid faulty or unreliable connections.

SUMMARY

An illustrative example wire processing machine includes at least one blade configured for at least one of cutting a conductor or at least piercing an insulation layer on the conductor. At least one gripper assembly includes a gripper configured to at least temporarily grasp a portion of a conductor during a wire processing operation. A generator, which is part of the gripper assembly, is configured to radiate a field toward a conductor. The gripper assembly also includes a detector that is configured to detect at least some of the field propagated along the conductor. A processor is configured to determine when a change in the propagated field detected by the detector indicates contact between a conductor and the blade.

An illustrative example conductor monitor device includes a generator electrode configured to radiate an electrical near field toward a conductor. A detector is configured to detect at least some of the field propagated along the conductor. A processor is configured to determine whether there is a change in the propagated field detected by the detector. The electrical near field has a frequency and a transmission wavelength. The detector has a dimension that is smaller than the transmission wavelength. The electrical near field has effectively no magnetic field component in a vicinity of the detector based on a relationship between the detector dimension and the transmission wavelength.

The various features and advantages of disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the description can be briefly described as follows.

DETAILED DESCRIPTION

An example conductor monitoring device20is schematically shown inFIG. 1. A generator or transmitter22is configured to radiate a field schematically shown at23toward a conductor24. The generator or transmitter22comprises at least one electrode in this example.

A detector or receiver26is configured to detect at least a portion of a field schematically shown at25that results from a signal induced in the conductor24that is propagated along the conductor24. The induced signal in the conductor24results from the radiated field23. In at least one sense, the conductor24acts like an antenna that radiates the field schematically shown at25in a manner that it can be detected by the detector26.

The detector or receiver26comprises at least one electrode that is situated relative to the conductor24and the generator22so that the detector26will detect the field schematically shown at25instead of directly detecting the field23that is radiated from the generator22. InFIG. 1, a spatial arrangement as schematically represented by the larger distance or spacing S1between the generator22and the detector26compared to a smaller distance or spacing S2between the detector26and the conductor24facilitates the detector26receiving or detecting the field25instead of the field23. Given this description, those skilled in the art will realize how to arrange the generator22and detector26in a manner that facilitates the detector26detecting at least some of the field25that radiates from the conductor24.

In at least one example, the field23effectively comprises an electric field without a magnetic component. Such an electric field is referred to as an electrical near field in this description. Radiating the field23toward the conductor24indirectly or remotely injects electrical energy into the conductor24. The electric field23effectively induces current or a signal that is propagated along the conductor24. In the illustrated examples, no electrically conductive, physical connection between the generator22and the conductor24is required. Detection is also indirect or remote because no electrically conductive, physical connection between the detector26and the conductor24is required.

Using indirect or remote signal injection allows for monitoring the quality of a conductor during a wire handling or processing operation without requiring any physical, electrically conductive connection for introducing an electrical signal onto the conductor24. Additionally, using indirect or remote generation and detection allows for the monitoring device20to be more readily incorporated into a variety of wire processing machines. The generator22and detector26do not require any modification to an existing wire processing machine although some embodiments may have specially designed components for supporting or incorporating the generator22and detector26. The generator22and detector26can be incorporated into a machine design or be configured as separate or distinct device that can be used in conjunction with a wire processing machine.

In at least one example, the generator22uses very low frequency range radiation, such as an electric field having a wavelength that is less than 100 kHz. In some examples, a frequency range between about 40 kHz and about 70 kHz is used. One feature of that frequency range is that its corresponding wavelength is within a range of a length of a spool of wire used with wire processing machinery (e.g., thousands of meters). When there is correspondence between the wavelength and the wire length, the spool of wire may serve as a form of a half wave dipole antenna or a quarter wave monopole antenna, which may boost the signal of the detector26.

Another feature of the frequency range between 40 kHz and 70 kHz is that the corresponding wavelength is on the order of about 4 kilometers to about 8 kilometers (or 4,000,000 mm to 8,000,00 0mm) When an electrode on the order of about 20 mm in length is used as the generator22or detector26, the transmitted wavelength (λTx) is much larger than the length of the electrode. In some embodiments, a ratio of the detector dimension to the transmission wavelength is less than about 0.000005.

According to the Maxwell-Faraday equation ▾×E=−δB/δt a time-varying magnetic field is always accompanied by a spatially-varying, non-conservative electric field and vice versa. Also, when there is no spatially-varying electric field, there is no magnetic field present. With a large enough wavelength-to-electrode dimension ratio, the magnetic component of the radiated field is effectively zero and there is no wave propagation. The result using an example embodiment of this invention, which includes a sufficiently long wavelength and a sufficiently small electrode, is a quasi-static electric field that can be used for sensing conductive objects such as wire. In such an embodiment there is effectively no varying electrical field and no magnetic field propagation within the small electrode space.

Accordingly, some example embodiments of this invention utilize an electrical near field. When a conductor is shorted to ground, the electrical near field collapses accordingly.

Such a frequency range (i.e., 40-70 kHz) also allows for incorporating conductor quality monitoring without introducing any concern for adversely affecting a machine operator. Additionally, such low frequency radiation is much less likely to cause any interference with the operation of the wire processing machine or other devices in the vicinity of that machine. Additionally, using a wavelength range on the order of about 40 kHz to about 70 kHz is below the AM radio wave spectrum so that there is no concern with regulation compliance, such as that required by the United States Federal Communication Commission for higher frequencies.

FIG. 2schematically illustrates additional selected details of an example conductor monitoring device20. In this example, a processor28communicates with the generator22and the detector26. The processor28is configured to determine when a change in the propagated field25detected by the detector26indicates contact between the conductor24and a conductive blade of a wire processing machine.

In the example ofFIG. 2, a power supply30provides power to the generator22, detector26and processor28. As the detector26detects a signal or field radiated from the conductor24, it generates an output that is provided to a buffer amplifier32to increase the power or amplitude of a detected signal. A rectifier34facilitates shaping the waveform of the detected signal amplified by the amplifier32. At least one band pass filter36filters out noise, for example, from the signal before it is provided to a comparator38. In this example, the processor28receives information from the comparator38that indicates a state of the signal or field detected by the detector26.

The example ofFIG. 2includes an output40, such as a visual display, to communicate information regarding the quality of a conductor that has been cut, for example, and otherwise handled according to a desired wire handling operation. The processor28controls the display or output40in one of a variety of manners, one of which is described below. In some examples, the output40comprises an interface for communications between the processor28and a wire handling machine. This allows for the processor28, for example, to obtain information regarding a particular stage of the wire processing operation so that the processor28can associate information regarding that which is detected by the detector26and a portion of a wire processing operation to provide a meaningful output.

FIG. 3schematically illustrates selected portions of a wire processing machine50including a wire feed device52that feeds the conductor24along appropriate portions of the machine50to carry out a desired wire processing operation. A wire processing operation that involves cutting the conductor24to a desired length and stripping insulation from at least one cut end of the wire is considered for discussion purposes.

As shown inFIG. 3, the machine50includes a cutting device54that includes at least one electrically conductive cutting blade56. A stripping portion58includes at least one electrically conductive stripping blade60that is configured to strip insulation from the exterior of the conductor24. The output40inFIG. 3includes a DC wave form plot62. A DC wave form includes a first, positive value shown at70during the portion of the wire processing operation schematically shown inFIG. 3. As the conductor24is being fed along the machine toward the cutting portion54, the generator22is inducing an electrical signal that is propagated along the conductor24and detected by the detector26. The resulting output shown at70represents the determination made by the processor28regarding a value or characteristic of that which is detected by the detector26, such as a positive field25radiated from the conductor24.

FIG. 4schematically shows another stage of the wire processing operation. InFIG. 4, the cutting blade56moves into contact with and cuts through the conductor24. The cutting blade56is electrically conductive. Contact between the cutting blade56and the conductive wires of the conductor24effectively results in grounding the signal that is propagated along the conductor24, which results from the field generated by the generator22.

Contact between the cutting blade56and the conductive wires of the conductor24is represented in the output40when the DC signal value drops as is shown at72. After the cutting blade56is retracted and no longer in contact with the conductive wires of the conductor24, the DC signal returns to a positive value shown at74.

In embodiments where the processor28is provided with information regarding the stage of operation being accomplished by the machine50, the processor28may provide an indication that the signal change at72corresponds to a desired cutting of the wire accomplished by the cutting blade56.

FIG. 5schematically illustrates a subsequent stage of the example wire processing operation. At this stage, the stripping blade60moves into contact with at least an exterior of the conductor24. Provided that the stripping blade60, which is electrically conductive, does not make contact with any of the conductive wires of the conductor24, the signal value or amplitude remains essentially constant and positive as shown at74in the output40ofFIG. 5.

FIG. 6shows a later stage of the wire processing operation after the stripping blade60has cut through an insulation layer78and the conductor24has been retracted by the wire feed device52(e.g., drawn or pulled to the left according to the drawing) so that conductive wires76are exposed at one end of the conductor where the cut was made. The removed plug of insulation shown at78′ may be disposed of in a known manner.

The output40inFIG. 6includes a positive value of the DC signal representation at80. Given that the DC signal remained at the same value from74to80, there was no electrically conductive contact between the stripping blade60and the conductive wires76.

FIG. 7schematically illustrates an example conductor24that is considered acceptable because the wire cutting and stripping operation was successful. As shown inFIG. 7, a plurality of conductive wires76are exposed at the end of the conductor24and the insulation layer78covers another portion of the conductor. The exposed conductive wires76may then be used for establishing a desired type of connection, such as a crimp connection, for incorporating the conductor24into an assembly, such as a vehicle wire harness.

The output40inFIG. 6represents a graphical illustration of a monitored wire cutting and insulation stripping operation that was accomplished in a manner that provides a desired condition of the resulting conductor. While a graphical illustration is shown as the example output40, some embodiments of wire processing monitors designed according to this invention provide alternative forms of output such as written words or colors that provide an indication of a positive or negative result at various stages of the wire processing operation.

FIG. 8schematically illustrates a wire stripping stage of a wire processing operation in which the stripping blade60makes undesirable contact with at least one of the conductive wires76of the conductor24. As shown in the output40, the DC signal value drops at82before it returns to a positive value shown at80. This grounding or reduction in the signal propagated along the conductor24is detected by the detector26. The reduced signal value shown at82corresponds to the stripping blade60effectively grounding the signal or field propagated along the conductor24when there is contact between the electrically conductive stripping blade60and one or more of the conductive wires of the conductor24. InFIG. 8, the resulting cut wire includes a damaged or improperly cut bundle of exposed wires76′ at one end of the cut conductor. The output40including the signal drop at82provides an indication that this wire should be rejected and not incorporated into a device or assembly that requires a properly cut and stripped wire.

The conductor quality monitor provides an ability to detect a variety of types of damage or alteration made to the conductor24during the wire processing operation.FIG. 9schematically illustrates one example scenario in which a plurality of shorter or broken wire ends90are included among the exposed wires76′ resulting from contact between those individual wires and the stripping blade60.FIG. 10schematically illustrates an arrangement in which some of the wires76′ are cut short having ends at92. The type of contact between the stripping blade60and the wires resulting in an arrangement as schematically shown inFIGS. 9 and 10may be caused by a variety of circumstances. There may have been a malfunction in the operation of the stripping portion58of the machine50, the conductor may have been presented to the stripping blade60in an unexpected position, or the conductive wires may not have been concentrically arranged uniformly within the insulation layer. These and other situations can be reliably detected using the conductor quality monitor device20of the illustrated example embodiment.

The configuration of the conductor quality monitor that includes a generator22and a detector26that allows for inducing and observing at least one electrical signal along a conductor without making contact with that conductor may take a variety of forms.FIG. 11schematically illustrates an example embodiment in which a base or plate100supports an electrode that operates as the generator22and another electrode that operates as the detector26. The electrodes may comprise flat plates or may have a U-shaped configuration, for example. A configuration such as that shown inFIG. 11allows for the monitoring device20to be placed at a variety of positions relative to a wire processing machine.

FIG. 12illustrates another example embodiment that includes a tubular configuration102through which the conductor24is passed during appropriate portions of the wire processing operation. In this example, a first cylindrical electrode serves as the generator22and the detector26comprises another cylindrical electrode. The conductor24is received within the tubes so that the signal or field detected by the detector26is induced in the conductor24by the generator22while the conductor24is within the tubes. There is no requirement for any electrically conductive, physical contact between any portion of the tubular configuration102and the conductor.

FIG. 13illustrates another example arrangement in which the conductor24is wound at least partially about a series of wheels or springs104and106. The generator22in this example includes at least one electrode associated with the wheels104and the detector106includes at least one electrode associated with the wheels106. Various portions of the illustrated example may be used as the electrodes for realizing the operation of the generator22and the detector26, respectively. For example, metallic bearings (not illustrated), axels110, fasteners112(e.g., nuts) or base plates114associated with the wheels or springs may operate as an electrode for purposes of realizing the function of the example generator22and detector26, respectively.

FIG. 14illustrates selected features of an example wire processing machine50that includes conductor quality monitoring capabilities. A gripper assembly120includes at least one gripper121having gripper surfaces122and124shown spaced apart from each other. During a wire processing procedure at least the gripper surface124moves relative to the surface122to close the gripper121onto a wire to a least temporarily grasp the wire between the surfaces122and124. In this example, the gripper assembly120supports blades60that are situated for piercing through and cutting insulation surrounding a conductor so that the insulation can be removed leaving an exposed portion of the conductor at an end of the wire.

In this example, the gripper assembly120includes a generator electrode22. In this particular embodiment the generator electrode22is supported on the gripper surface122. The generator electrode22generates an electrical near field that is injected into the conductor while the wire is grasped by the gripper121. The gripper assembly also includes a detector electrode26, which is supported on the surface122in this embodiment. The detector electrode26detects a field propagated along the conductor. The detector26and the generator22of this example operate consistent with the explanation provided above regarding generators and detectors.

One of the features of the embodiment ofFIG. 14is that the conductor quality monitoring components, such as the generator and detector electrodes are part of the gripper assembly120. This approach incorporates the conductor quality monitoring features into the wire processing machine50in a manner that does not require altering the configuration or operation of the machine and avoids any need to accommodate separate or standalone conductor quality monitoring sensors. The strategic placement of the generator electrode22and the detector electrode26also places conductor quality monitoring components at the location where the blades60will encounter the wire and possibly the conductor.

In the example embodiment ofFIG. 14, the generator electrode22and the detector electrode comprise generally flat strips of electrically conductive material. Wired connections between a processor and those electrodes may be made in a manner that does not interfere with or otherwise complicate the movement or operation of other parts of the machine50. Such wired connections may be useful for providing power to either electrode and communicating signals to the processor, for example.

FIGS. 15aand 15billustrate another example embodiment. The gripper assembly120′ is shown with a gripper121′ in an open position inFIG. 15aand in a closed or grasping position inFIG. 15bin which the gripper121′ of the gripper assembly120′ at least temporarily grasps (and possibly moves or manipulates) a wire. A mechanism130controls the position of the portions of the gripper121′ to realize the desired position (e.g., open or closed) of the gripper121′. In this example, at least part of the gripper121′ operates as the generator electrode22. This example includes gripper fingers or jaws that are situated to be on opposite sides of a wire. One of the fingers or jaws is labeled22in this example because it is configured to operate as the generator electrode22. The electrical near field is radiated from a surface of the finger or jaw22facing toward the wire in this example. The other finger or jaw of the gripper121′ is labeled26because it is configured to operate as the detector electrode26. This embodiment further reduces the number of individual pieces or components needed to perform desired wire processing operations and monitor the resulting quality of a conductor. For example, there is no requirement for any separate electrodes or additional electrode material added to the gripper assembly120′. Instead, the gripper121′ itself operates as the generator and detector of the conductor monitoring portion of the machine.

FIGS. 16aand 16bshow another example embodiment of a gripper assembly120″. This example includes two grippers121″ that selectively grasp at least one wire. At least one of the fingers or jaws of one of the grippers121″ is configured to operate as the generator22of the conductor quality monitor for injecting an electrical near field into a conductor of a wire. At least one of the gripper fingers or jaws of the other gripper121″ operates as the detector26.

Other embodiments include gripper assemblies arranged similar to the arrangements ofFIGS. 15 and 16including electrodes situated on one or more surfaces of the gripper fingers or jaws in a similar manner in which the electrodes are supported on a gripping surface as shown inFIG. 14. The examples ofFIGS. 14-16demonstrate several ways to integrate conductor monitoring sensor components into a gripper assembly of a wire processing machine, such as by securing a detector or generator electrode on a gripper component or by using a gripper component, itself, as the detector or generator.

One feature of using a gripper component as a detector or generator electrode or supporting an electrode on a gripper component is that the electrical near field is directed toward the conductor while reducing or eliminating movement of the conductor relative to the electrode. The gripper component provides stability to the conductor which reduces or eliminates vibratory or repeated movement of the conductor within the electric field. Reducing such movement may facilitate more accurate measurement and detection of blade contact with the conductor.

In some embodiments the processor28is programmed to recognize when there is undesired contact between a blade and a conductor. The processor28provides information regarding such conditions to a machine controller in a format that the machine controller recognizes as requiring a change in machine operation, such as altering the position (or advancement) of one or more cutting blades to avoid such undesired contact. In some embodiments, the processor28provides real time feedback to the machine controller to allow for adjustment to the wire processing machine operation on a continuous or periodic basis depending on the needs of a particular situation. Those skilled in the art who have the benefit of this description will realize how to program or design a processor to accomplish such feedback to meet their particular needs.

FIG. 17schematically illustrates selected portions of a wire processing machine140including a monitoring device20, a machine controller142, a blade controller144, a motor146that causes movement of blades148to achieve a desired amount of cutting or insulation stripping so that the conductor24has desired characteristics. In this example, the monitoring device20provides information to the machine controller142regarding an amount of time that the blades148are in contact with the conductor24and other conductors processed by the machine140. Such information is useful for the machine controller142to communicate with the blade controller144to cause an adjustment in blade position.

FIG. 18illustrates one example technique of using such contact time information. In this example, a threshold contact time, such as 250 milliseconds, is set as an indicator when there is an undesired amount of contact between the blades148and a conductor24. The graph150shows the amount of time there is contact between the blades148and a conductor24for a series of wires processed by the machine140. As can be appreciated from the drawing, the contact time is below the threshold152through the first fifty wires that are processed. Between the fiftieth and sixtieth wires, the contact time exceeds the threshold as shown at154. The machine controller interprets that information as a need to open the blades148, to adjust an amount of movement of the blades, or both. Given that information, the controller142determines an adjustment and communicates that to the blade controller144. Depending on whether the contact time remains above the threshold or returns to an acceptable level, the controller142may determine how to make further adjustments to the blade position. As shown inFIG. 18, the contact time returns to acceptable levels for at least the next forty wires so no further adjustment was needed.

The control features illustrated throughFIGS. 17 and 18allow for the monitoring device to enhance the machine operation as the controller142may adjust to differences in wires in a dynamic fashion. For example, when a portion of a lot of wire processed by the machine varies from other portions of the lot (e.g., a variation in conductor diameter) undesired contact with the conductors may be avoided based on automated adjustments to the machine operation in real time. The monitoring device20provides real time feedback regarding machine operation in such an embodiment.

Several different embodiments are illustrated and described above. The various features of those embodiments may be combined in ways not necessarily described or illustrated. In other words, the features of any one disclosed embodiment may be combined with one or more features of any of the other disclosed embodiments. Those skilled in the art who have the benefit of this description will realize what configuration of the example features consistent with the preceding description will best suit their particular needs.

The disclosed example conductor quality monitor devices, wire processing machine components, and grippers allow for efficiently and reliably detecting when a wire is damaged or potentially damaged during a wire processing operation, such as one that involves cutting a wire and stripping insulation from it. The contactless monitoring device includes the feature of not requiring any physical, electrically conductive connection with the conductor, itself, but instead uses a remotely induced signal or field (i.e., without a direct, electrically conductive, physical connection) propagated along the conductor and remote detection of that signal or field. Additionally, the example devices described above can be utilized with a variety of wire processing machines without requiring any modification to those machines.