Patent Publication Number: US-2005125980-A1

Title: System and method of constructing wire wrap well screens

Description:
TECHNICAL FIELD  
      This invention relates to wire wrapped screens, and more particularly to an improved system and method for constructing wire wrapped screens such as those used down hole in subterranean well applications.  
     BACKGROUND  
      A wire wrapped screen is a tubular that incorporates a wire mesh adapted to filter particulate from passage between an exterior and an interior of the screen. One or more screens and other tubulars may be concentrically nested to form a well screen assembly. The well screen assembly is typically mounted in-line in a tubing string and run down hole in a subterranean well. Fluids are then produced from the formation or flowed into the well bore through the tubing string, and the well screen assembly operates to filter passage of particulate between the interior and the exterior of the tubing string.  
      The wire wrapped screen is constructed from a wrap wire that is helically wound around a body, for example, a plurality of elongate wires arranged to define a cylinder. The wire wrapped screen is generally fabricated by rotating the body about its central longitudinal axis, securing the wrap wire as the body rotates, and moving the body along its longitudinal axis relative to the incoming wrap wire, so that the wrap wire wraps in a helical fashion. Uniformity in the helical wraps is desired, because the distance between adjacent wrap wires, or screen gauge, is specified based on the size of particulate to be filtered. Variances in the wrap wire width affect the screen gauge. The rate at which the body is moved along its longitudinal axis also affects the screen gauge. If this rate is improperly set or varies, or the wrap wire width changes, the rate at which the body is moved along its longitudinal axis must be adjusted to obtain or maintain the desired screen gauge. Therefore, there is a need to produce a wire wrap screen having uniformity of screen gauge.  
     SUMMARY  
      The present invention encompasses a system and method for producing a wire wrap screen that has improved uniformity of the screen gauge.  
      One illustrative embodiment includes a device for constructing a wire wrapped screen. The device has a screen body carrier adapted to carry an elongate screen body being rotated substantially about a screen body longitudinal axis. A wrap wire feed is provided and adapted to guide a wrap wire being wound about the screen body. The screen body carrier and wrap wire feed cooperate to move at least one of the screen body and wrap wire relative to the other and substantially parallel to the screen body longitudinal axis to wrap the wrap wire substantially helically about the screen body as the screen body rotates. A gauge measurement device is provided and adapted to measure a dimension between adjacent wraps of the wrap wire on the screen body. A controller is coupled to the gauge measurement device and adapted to adjust the wrapping of the wrap wire about the screen body to affect the dimension between adjacent wraps of wire on the screen body in relation to the measured dimension between adjacent wraps of the wrap wire on the screen body.  
      A wrap wire measurement device may be provided as an alternative to the gauge measurement device or in combination with the gauge measurement device. The wrap wire measurement device is adapted to measure a dimension of the wrap wire. If a wrap wire measurement device is provided, the controller may be coupled to the wrap wire measurement device and adapted to adjust the wrapping of the wrap wire about the screen body to affect the dimension between adjacent wraps of wire on the screen body in relation to the measured dimension of the wrap wire.  
      Another illustrative embodiment includes a method of constructing a screen. According to the method a wire is wrapped substantially helically about a screen body as the screen body rotates. At least one of the wire and screen body is translated substantially parallel to a screen body longitudinal axis. A dimension between adjacent wraps of the wire on the screen body is measured continuously during one or more intervals while wrapping the wire about the screen body. The wrapping of the wire about the screen body is adjusted to affect the dimension between adjacent wraps of wire on the screen body in relation to the measured dimension between adjacent wraps of the wire.  
      As an alternative to measuring a dimension between adjacent wraps of the wrap wire or in combination with the same, the method can include measuring a dimension of the wire continuously during an interval while wrapping the wire about the screen body. If a dimension of the wire is measured, then the method may include adjusting the wrapping of the wire about the screen body to affect the dimension between adjacent wraps of wire on the screen body in relation to the measured dimension of the wire.  
      Another illustrative embodiment includes a device for constructing a wire wrapped screen. The device has a screen body carrier adapted to carry an elongate screen body. A wrap wire feed is provided and adapted to guide a wrap wire being wound substantially helically about the screen body. A measurement device is provided for measuring at least one of a dimension between adjacent wraps of wire about the screen body and a dimension of the wrap wire. A marking device is provided and actuable to mark the wire wrapped screen. A controller is coupled to the measurement device and the marking device. The controller is adapted to actuate the marking device in relation to a measured dimension from the measurement device.  
      Another illustrative embodiment includes a method of constructing a screen. According to the method wrapping a wire substantially helically about a screen body. At least one of a dimension between adjacent wraps of wire about the screen body and a dimension of the wrap wire is measured. The screen is marked while wrapping the wire about the screen body in relation to the measured dimension.  
      Another illustrative embodiment includes a device for constructing a wire wrapped screen. The device has a screen body carrier adapted to carry an elongate screen body and a wrap wire feed adapted to guide a wrap wire being wound substantially helically about the screen body. At least one measurement device is provided and adapted to measure at least one of a dimension between adjacent wraps of wire about the screen body and a dimension of the wrap wire while the wrap wire is being wrapped about the screen body.  
      Another illustrative embodiment includes a method of constructing a screen. According to the method a wire is wrapped substantially helically about a screen body. At least one of a dimension between adjacent wraps of wire about the screen body and a dimension of the wrap wire is measured while the wire is being wrapped substantially helically about the screen body.  
      The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.  
    
    
     DESCRIPTION OF DRAWINGS  
       FIG. 1  is a perspective view of an illustrative wire wrapping system constructed in accordance with the invention;  
       FIG. 2  is a perspective detail view of the head, wrap wire feed assembly, and welding arm of the wire wrapping system of  FIG. 1 ;  
       FIG. 3  is a schematic of a control module for use in a wire wrapping system constructed in accordance with the invention;  
       FIG. 4A  is a cut-away perspective view of a wire wrapped screen having a tubular screen body and without axial body wires;  
       FIG. 4B  is a cut-away perspective view of a wire wrapped screen having a tubular screen body with axial body wires; and  
       FIG. 5  is a cut-away perspective view of a wire wrapped screen having a screen body including another wire wrapped screen with external axial body wires. 
    
    
      Like reference symbols in the various drawings indicate like elements.  
     DETAILED DESCRIPTION  
      Referring to  FIGS. 1 and 2 , an illustrative wire wrapping system  10  constructed in accordance with the invention is depicted fabricating an elongate wire wrapped screen  12  suitable for incorporation into a well screen assembly (not specifically shown). The wire wrapped screen  12  is constructed from a plurality of axial body wires  14  and a wrap wire  16 . The axial body wires  14  extend along a length of the wire wrapped screen  12  and are arranged to define a cylinder and spaced from one another to define longitudinal gaps. The wrap wire  16  is substantially helically wrapped about and joined to the axial body wires  14 . Although described herein with reference to a wire wrapped screen  12  having a wrap wire  16  helically wrapped about axial body wires  14 , the concepts described herein are equally applicable to a wire wrapped screen having a wrap wire  16  helically wrapped around an apertured body  15  with or without axial body wires  14  (see  FIG. 4 ), such as a slotted or apertured tubular or an expanded screen, or having multiple layers of axial body wires  14  and wrap wire  16  (see  FIG. 5 ).  
      In the illustrative wire wrapping system  10 , the wrap wire  16  is joined to the axial body wires  14  by welding, but it is within the scope of the invention that the wrap wire  16  and axial body wires  14  be joined by other methods, including brazing, adhesive, wire tie, or otherwise. For convenience of reference, an axial centerline of the wire wrapped screen  12 , to which axial body wires  14  are substantially parallel and substantially equally radially offset from, is referred to herein as axis A-A.  
      The illustrative wire wrapping system  10  includes a head  20  driven to rotate about axis A-A. In the illustrative wire wrapping system  10 , the axial body wires  14  pass through a plurality of apertures  22  in the head  20  to rotate about axis A-A as the head  20  rotates. The apertures  22  are arranged in a circle, and thereby hold the axial body wires  14  in spaced relation defining a cylinder. The head  20  resides about one end of an elongate bed  24  that extends substantially parallel to, but offset from, axis A-A. Opposite the elongate bed  24  and extending outward from the head  20  is a tubular wire support body  18  in which the axial body wires  14  rest.  
      The elongate bed  24  carries a tail support  26  having a tail chuck  28  adapted to receive and grasp ends of the axial body wires  14 . The tail chuck  28  cooperates with the head  20  to support the axial body wires  14  substantially parallel to axis A-A. The tail chuck  28  is also driven to rotate about axis A-A at the same rate as the head  20  The tail support  26  may be adapted to move at an adjustable rate along the length of the elongate bed  24 , substantially parallel to axis A-A. Moving the tail support  26  away from the head  20  along the elongate bed  24  draws the axial body wires  14  from the tubular wire support body  18 , through the head  20 , and along axis A-A.  
      In the illustrative wire wrapping system  10 , the tail support  26  is moved using a helical drive screw  36 . The tail support  26  receives the helical drive screw  36  with a female profile  38  configured such that rotation of the drive screw  36  in one direction screws the tail support  26  away from the head  20  and rotation of the drive screw  36  in an opposite direction screws the tail support  26  toward the head  20 . The rate at which the tail support  26  moves along the elongate bed  24  is proportional to the rotational speed of the helical drive screw  36 . The helical drive screw  36  is thus driven to move the tail support  26  along the elongate bed  24 . Although discussed with respect to a helical drive screw  36  and female profile  38 , it is within the scope of the invention that other drive arrangements be utilized. For example, the tail support  26  may be moved along the elongate bed  24  using a linear actuator, gear train, or other system.  
      As best seen in  FIG. 2 , a wrap wire feed assembly  30  extends laterally outward from the elongate bed  24  and substantially perpendicular to the axis A-A. The wrap wire feed assembly  30  defines a wire track  32  that receives wrap wire  16  from a source reel  35  and guides the wrap wire  16  to the axial body wires  14  in a controlled manner. A height of the wire track  32  is adjustable relative to the axis A-A, so that the wrap wire  16  can be guided to tangent the outward surface of the cylinder defined by the axial body wires  14 .  
      In the illustrative wire wrapping system  10 , the wire track  32  includes a plurality of circumferentially grooved, cylindrical rollers  34 , oriented to rotate in substantially perpendicular planes and aligned along a common axis. The rollers  34  receive the wrap wire  16  in their respective groove and cooperate to guide the wrap wire  16  substantially perpendicular to, but offset from, axis A-A to tangent the axial body wires  14 . Although described herein with respect to a plurality of cylindrical rollers, it is within the scope of the invention to utilize other configurations of wire track  32 . For example, the wire track  32  can be a simple grooved pathway or otherwise.  
      In an instance where the tail support  26  is adapted to be selectively affixed to the elongate bed  24  at differing distances from the head  20 , the wrap wire feed assembly  30  or a portion thereof, is carried to move along the elongate bed  24  substantially parallel to axis A-A. As above, the wrap wire feed assembly  30  can be moved using a helical drive screw, linear actuator, gear train or other system.  
      A welding arm  40  is movably positioned over the elongate bed  24  opposite the wrap wire feed assembly  30 . The welding arm  40  includes a compression wheel  42  rotatable in a plane that is substantially perpendicular to axis A-A and substantially aligned with the incoming wrap wire  16 . Aback-up mandrel  45  extends outward from the head  20  centered on axis A-A and encircled by the axial body wires  14 . The back-up mandrel  45  is sized so that its outer circumference substantially abuts the inward facing surfaces of the axial body wires  14  and is axially positioned along axis A-A to substantially coincide with the incoming wrap wire  16 . The compression wheel  42  is movable into and out of a position by which its outer circumference bears against the wrap wire  16 , pressing the wrap wire  16  into contact with the axial body wires  14  and against the back-up mandrel  45 . The amount of force exerted by the compression wheel  42  on the wrap wire  16  and axial body wires  14  is adjustable by adjusting the position of the pressing wheel  42 . A power source  44  is coupled to the head  20  and to the compression wheel  42  to apply a current across the head  20  and pressing wheel  42  through the axial body wires  14  and wrap wire  16  to compression weld the axial body wires  14  and wrap wire  16  at the point of compression by the compression wheel  42 .  
      In the illustrative wire wrapping system  10 , the welding arm  40  is mounted at one end to a fixed body  46  and rotatable about an axis parallel, but offset from, axis A-A. A linear actuator  48 , such as a hydraulic or pneumatic piston or an electro-mechanical device, links the welding arm  40  and fixed body  46 . Extending the linear actuator  48  rotates the welding arm  40  towards the wire wrap screen  12  being constructed, and once the compression wheel  42  is pressing the wrap wire  16  and axial body wires  14  against the back-up mandrel  45 , further extending the linear actuator increases the force exerted on the wrap wire  16  and axial body wires  14 . Retracting the linear actuator  48  decreases the force exerted on the wrap wire  16  and axial body wires  14  and retracts the welding arm  40  away from the wire wrap screen  12  being constructed.  
      A wrap wire dimensional analyzer system  50  is positioned to measure one or more dimensions of the wrap wire  16  received from the source reel  35 . The dimensional analyzer system  50  may be positioned in the wrap wire feed assembly  30  with portions of the wrap wire feed assembly  30  on either side of the dimensional analyzer system  50  configured to stabilize the passage of the wrap wire  16  through the dimensional analyzer system  50 . In the illustrative wire wrapping system  10 , the dimensional analyzer system  50  includes a light projector unit  52  opposed to and projecting light across the incoming wrap wire  16  into a light receiver unit  54 . The light receiver unit  54  then determines at least one dimension of the wrap wire  16 , for example, by measuring the width of light projected onto the receiver unit  54  as compared to the width of the light emitted by the light projector unit  52 . In the illustrative wire wrapping system  10 , the light projector unit  52  is positioned to project light down on the incoming wrap wire  16  into the light receiver unit  54  substantially perpendicular to, but offset from, the axis A-A to determine a width of the wrap wire  16 ; however, it is within the scope of the invention that the light projector unit  52  and light receiver unit  54  or multiple light projector units  52  and receiver units  54  be positioned to determine additional or alternate dimensions of the incoming wrap wire  16 . The dimensional analyzer system  50  of the illustrative wire wrapping system  10  also optionally includes a video imager, in this instance incorporated into the light projector unit  52 , directed at the wrap wire  16  to capture one or more video images of the wrap wire  16  fed through the wrap wire feed assembly  30 . It is within the scope of the invention to use alternate or additional devices to the light projector unit  52  and light receiver unit  54  to measure the wrap wire  16 , including, for example, mechanical measurement devices, acoustic measurement devices, other optical or light-based measurement devices (ex. a video imager device that digitally images the wrap wire and determines one or more dimensions from the image), or otherwise. The wrap wire dimensional analyzer system  50  can be operated to measure the wrap wire  16  periodically or continuously in real-time.  
      A screen gauge analyzer system  60  is positioned to measure the gauge, or distance between adjacent wraps of wrap wire  16 , on the screen  12 . The screen gauge analyzer system  60  may be positioned above the elongate bed  24  and below the wire wrapped screen  12  being fabricated to measure the gauge at a tangent of the wire wrapped screen  12 . In the illustrative wire wrapping system  10 , the screen gauge analyzer system  60  includes a light projector unit  62  opposed to and projecting light across the incoming wrap wire  16  into a light receiver unit  64 . The light receiver unit  64  then determines a screen gauge of the wire wrap screen  12  by measuring the width of light projected onto the receiver unit  64  as compared to the width of the light emitted by the light projector unit  62 . In the illustrative wire wrapping system  10 , the light projector unit  62  is positioned to project light across an edge of the wire wrapped screen  12  into the light receiver unit  64  substantially perpendicular to, but offset from, the axis A-A to determine a gauge of the wire wrapped screen  12 ; however, it is within the scope of the invention that the light projector unit  62  and light receiver unit  64  or multiple light projector units  62  and receiver units  64  be positioned to determine the screen gauge at additional or alternate positions. The screen gauge analyzer system  60  of the illustrative wire wrapping system  10  also optionally includes a video imager, in this instance incorporated into the light projector  62 , directed at the wire wrapped screen  12  to capture one or more video images of the wire wrapped screen  12 . It is within the scope of the invention to use alternate or additional devices to the light projector unit  62  and light receiver unit  64  to measure the screen gauge, including, for example, mechanical measurement devices, acoustic measurement devices, other optical or light-based measurement devices (ex. a video imager device that digitally images the wrap wire and determines one or more dimensions from the image), or otherwise. The screen gauge analyzer system  60  can be operated to measure the gauge periodically or continuously in real-time.  
      The wire wrapping system  10  includes a control module  70 . The control module  70  includes a user interface panel  72  having one or more displays  74 , one or more user input devices  76  (ex. keyboard, touchscreen, voice recognition system), and one or more removable media drives  78  for reading and or writing computer readable media. The control module  70  may also include a printer  84  or other data output device.  
      Referring to  FIG. 3 , the control module  70  includes a processor  80  and a computer readable media  82 , for example a memory or hard drive. The computer readable media  82  includes operating instructions for the processor  80  for operation of the control module  70  described herein. The computer readable media  82  can be a removable media inserted through the drive  78 , a media installed in the control module  70 , or a combination of both. The control module  70  is coupled to the wire wrap dimensional analyzer system  50  to receive data about the incoming wrap wire  16 . The control module  70  is also coupled to the screen gauge analyzer system  60  to receive data about the screen  12  being produced. The control module  70  is adapted to control the speed at which the head  20  rotates and the rate at which the tail support  26  moves along the elongate bed  24 . In the illustrative wire wrapping system  10  described herein, the control module  70  controls the rate at which the tail support  26  moves along the elongate bed  24  by controlling the rotational speed of the helical drive screw  36 . Also, the control module  70  can take the length of the wire wrap screen  12  being constructed as an input, and can stop the screen construction process when the specified length is reached.  
      In constructing a wire wrapped screen  12 , the control module  70  operates to produce a desired screen gauge. From operator input including the desired screen gauge, the control module  70  measures the screen gauge as the wire wrapped screen  12  is being produced, compares the measured screen gauge to the desired screen gauge, and adjusts the rate at which the tail support  26  moves away from the head  20  to maintain the desired gauge. Measurements of screen gauge are obtained from the screen gauge analyzer system  60 . Operator input may further include a desired tolerance for the screen gauge. If the screen gauge exceeds the tolerance, then the control module  70  adjusts the tail support  26  transit rate and/or the head  20  rotational rate to compensate. However, if the tolerance is not exceeded, then the control module  70  does not make an adjustment. The tolerance can include an acceptable screen gauge high and low tolerance. Using measurements obtained from the screen gauge analyzer system  60 , the control module  70  can be configured not only to display the currently measured screen gauge, but to log the screen gauge over an interval during the wrapping of the screen  12  or over the entire construction process. Knowing the tail support  26  transit rate, the control module  70  is able to log screen gauge against a longitudinal dimension of the wire wrapped screen  12 . In an instance where the screen gauge analyzer system  60  includes a video imager, the images captured from the video imager can be logged also, and can be logged against the longitudinal dimension of the wire wrapped screen  12 . Thereafter, the logged data can be output, for example, to the printer  84 , saved to a removable media by the media drive  78 , or accessed remotely on a network, if the control module  70  is coupled to a network.  
      The control module  70  may further measure a width dimension of the wrap wire  16  with the wrap wire dimensional analyzer system  50 , anticipate the effect of wrap wire  16  width variations on the screen gauge and thereafter correct for the wrap wire  16  width variations. For example, if the width of the wrap wire  16  increases and the tail support  26  transit rate is constant, the screen gauge decreases. If the width of the wrap wire  16  decreases, for a given tail support  26  transit rate, the screen gauge increases. Therefore, upon determining that the wrap wire  16  width has increased, the control module  70  can increase the tail support  26  transit rate, with a constant tail support  26  transit rate, decrease the head  20  rotational rate, or adjust both the tail support  26  transit rate and head  20  rotational rate to increase the screen gauge. Likewise, if the width of the wrap wire  16  decreases, the control module  70  can decrease the tail support  26  transit rate, with a constant tail support  26  transit rate, increase the head  20  rotational rate, or adjust both the tail support  26  transit rate and head  20  rotational rate to decrease the screen gauge. The distance from the point at which the wrap wire  16  width is measured to the point at which the wrap wire  16  is contacted to an axial body wire  14  can be input into the control module  70  together with the outer diameter of the cylinder defined by the axial body wires  14 . From this information, and knowing the rate at which the head  20  is turning, the control module  70  can make adjustments at substantially the same time that the change in wrap wire  16  width contacts the axial body wires  14  and begins to affect the screen gauge. Using measurements obtained from the wrap wire dimensional analyzer system  50 , the control module  70  can be configured not only to display the currently measured wrap wire dimension, but to log the wrap wire dimension over an interval during the wrapping of the screen  12  or over the entire construction process. Knowing the tail support  26  transit rate, the control module  70  is able to log wrap wire dimension against a longitudinal dimension of the wire wrapped screen  12 . In an instance where the wrap wire dimensional analyzer system  50  includes a video imager, the images captured from the video imager can be logged also, and can be logged against the longitudinal dimension of the wire wrapped screen  12 . Thereafter, the logged data can be output, for example, to the printer  84 , saved to a removable media by the media drive  78 , or accessed remotely on a network, if the control module  70  is coupled to a network.  
      The operator may manually control the amperage of the current supplied across the head  20  and compression wheel  42  to weld the wrap wire  16  and axial body wires  14 . Alternately or in combination with manual control, the control module  70  may be configured to control the power source  44 . In an instance where there is complete or partial manual control of the power source  44 , the control module  70  may output the desired amperage on the display  74  and the operator can make the appropriate adjustment to the power source  44 . In an instance where there is complete control of the power source  44  by the control module  70 , the control module  70  may output the desired amperage on the display  74 . The desired amperage can be determined by the control module  70  using parameters such as the rotational speed of the head  20 , the dimension of the wrap wire  16 , and inputs from the operator such as wrap wire  16  and axial body wire  14  materials and screen outer diameter input through the user input devices  76 . The amperage can be calculated from the screen parameters or values representative of the amperage may be retrieved from values stored and correlated to the screen parameters on a look-up table on the computer readable media  78 .  
      Optionally, the control module  70  may be adapted to control the amount of force applied by the compression wheel  42 , for example by controlling the extension or retraction of the linear actuator  48 . In an instance where the linear actuator  48  is a hydraulic or pneumatic cylinder, the control module  70  may be adapted to control the hydraulic or pneumatic pressure supplied to the cylinder. In an instance where the control module  70  is not configured to control the amount of force applied by the compression wheel  42 , the control module  70  may determine the appropriate force or force related parameter (ex. air pressure for a pneumatic linear actuator) and indicate the force or force related parameter to an operator via the display  74 . Exemplary loadings by the compression wheel  42  for various screen construction scenarios can be calculated from the screen parameters or values representative of the loadings can be retrieved from values stored and correlated to the screen parameters on a look-up table on the computer readable media  82 .  
      A screen marking device  66  can be provided adjacent to the wire wrapped screen  12  for placing markings on the wire wrapped screen  12  during the construction process. The control module  70  is coupled to the screen marking device  66  to actuate the screen marking device  66 . In the illustrative wire wrapping system  10 , the screen marking device  66  is an ink or paint jet operable to spray one or more colors of ink or paint on the exterior of the wire wrapped screen  12  in one or more patterns. The pattern may as simple as a dot or a undefined mark, or the screen marking device  66  may be operable to apply more complex patterns such as a symbols or text. It is within the scope of the invention that the screen marking device  66  be other than an ink or paint sprayer, for example, but in no means by limitation, a device that applies a physical tag, by adhesive or other form of attachment, to the wire wrapped screen  12  or a device that affects the finish of the wire wrapped screen  12  by chemical or mechanical etching or mechanical means.  
      The control module  70  can be adapted to mark the wire wrapped screen  12  according to data received from one or more of the wrap wire dimensional analyzer system  50 , the screen gauge analyzer system  60 , or the other systems coupled to the control module  70 . For example, the control module can actuate the marking device  66  in relation to variances in screen gauge and/or wrap wire dimension. If a variance in the measured screen gauge exceeds a specified high or low gauge marking tolerance (which may be different than the high and low screen gauge tolerance discussed above), the control module  70  actuates the marking system  66  to mark the wire wrapped screen  12 . The distance from where the screen gauge analyzer system  60  measures screen gauge to the point of marking by the marking system  66  can be input into the control module  70 . Using this distance together with the tail support  28  transit rate, screen outer diameter, and screen rotational rate, the control module  70  can actuate the marking system  66  to deposit a mark on the screen  12  that substantially coincides with the position of the measured variation on the wire wrapped screen  12  and indicating to the operator the location of the variation. If a variance in the measured wrap wire  16  dimension (ex. width) exceeds a specified high or low wrap wire marking tolerance, the control module  70  can actuate the marking device  66 , as above, and the mark can substantially coincide with the position of the measured variation on the wire wrapped screen  12 .  
      The color, symbol, size, and text of the marking can be used to communicate information about why the marking was placed on the wire wrapped screen  12 . For example, in an instance where the screen marking device  66  is operable to mark in two or more colors, one color can be used to indicate variances of screen gauge and another color used to indicate variances of wrap wire dimension. In another example, different colors can be used to indicate the magnitude and/or direction (over or under) of a variance. In an instance where the screen marking device  66  is operable to mark with different symbols, different symbols can be used to indicate variances of wrap wire dimension and screen gauge. Together with symbols, another indicator such as size of the marking, color of the marking, or text can used to indicate the magnitude and/or direction (over or under) of the variance. Parameters of the screen (for example, screen gauge, gauge tolerance, screen diameter or length, and screen material) as well as magnitude and/or direction of measured variances can be marked on the wrapped wire screen  12  in text. It is within the scope of the invention to use any combination of color, symbol, marking size, and text to denote the parameters of the wire wrapped screen  12  and/or the measured variances in screen gauge and wrap wire dimension.  
      The control module  70  and screen marking device  66  have applicability on a wire wrapping system without the ability to adjust for variances in screen gauge or wrap wire  16  dimension or with the ability to adjust for variances in screen gauge and/or wrap wire  16  dimension disabled. Thus, for example, in such a system, when a variance of screen gauge or wrap wire  16  dimension exceeds its respective high or low tolerance, the control module  70  operates to mark the wire wrapped screen  12  as discussed above. Thereafter, the operator can view the marking and, if necessary, attempt to repair the variance.  
      In each instance above, measurements and adjustments may occur periodically during the construction of the wire wrapped screen  12 , continuously during intervals (time or distance) in the screen construction, or continuously throughout the screen construction. Also, the control module  70  can be configured to display, as well as, log (to the computer readable media  82 ) the measurements obtained from the screen gauge analyzer system  60  and/or the wrap wire dimensional analyzer  50  and information about the screen construction process. The information about the screen construction process may include, for example, screen rotational speed, tail support  26  transit rate, linear actuator  48  position, and power source  44  amperage. The measurements and information can be logged during one or more intervals of the construction of the screen  12  or over the entire construction process. The measurements and information can be logged against a longitudinal dimension of the wire wrapped screen  12 . The logged data can be output, for example, to the printer  84 , saved to a removable media by the media drive  78 , or accessed remotely on a network, if the control module  70  is coupled to a network.  
      In operation, a plurality of axial body wires  14  are received in the head  20  with a short length of the axial body wires  14  extending outward from the head  20  over the elongate bed  24 . A remainder of the length of the axial body wires  14  rests in the tubular wire support body  18  opposite the elongate bed  24 . With the tail support  26  positioned near the head  20 , the end of each axial body wire  14  is secured in the tail chuck  28 . A length of the axial body wires  14  is chosen to be at least slightly longer than the specified length of the wire wrapped screen  12  being constructed. A wrap wire  16  is received in the wrap wire feed assembly  30  with its end proximal to the axial body wires  14 . The control module  70  prompts the user for inputs. The inputs depend on the configuration of the control module  70  as discussed above, but can include, among others, screen length, the outer diameter of the cylinder formed by the axial body wires, head rotational speed, desired screen gauge, screen gauge tolerance, wrap wire width, marking tolerances, power supply amperage, and compression wheel force.  
      The compression wheel  42  is lowered to compress the wrap wire  16  and the axial wires  14  against the back-up mandrel  45 . The amount of force exerted by the compression wheel  42  is adjusted by the operator or by the control module  70  as discussed above. Upon application of the compression wheel  42  against the wrap wire  16  and axial body wires  14 , the control module  70  can begin rotating the head  20  and tail chuck  28  while applying amperage across the interface of the wrap wire  16  and axial body wires  14  to weld the wrap wire  16  to the axial body wires  14 . Simultaneously, the control module  70  operates to control the transit rate of the tail support  26  to obtain the desired screen gauge.  
      Utilizing inputs from the screen gauge analyzer system  60 , the control module  70  increases, decreases, or maintains the transit rate of the tail support  26  and/or the rotational rate of the head  20  (and thus axial body wires  14 ) to maintain the desired screen gauge. If the screen gauge increases from the desired screen gauge, the control module  70  decreases the transit rate of the tail support  26  and/or increases the rotational rate of the axial body wires  14 . If the screen gauge decreases from the desired screen gauge, the control module  70  increases the transit rate of the tail support  26  and/or decreases the rotational rate of the axial body wires  14 . When the desired screen gauge is reached or if the measured screen gauge does not substantially depart from the desired screen gauge, the control module  70  maintains the transit rate of the tail support  26  and the rotational rate of the axial body wires  14 . In an instance where a high and low tolerance is an input to the control module  70 , the control module adjusts the transit rate of the tail support  26  and/or rotational rate of the axial body wires  14  to maintain the screen gauge within the specified tolerance. If a variance in the screen gauge exceeds a specified high tolerance, the control module  70  operates to decrease the transit rate of the tail support  26  and/or increase the rotational rate of the axial body wires  14 . If the variance in the screen gauge exceeds a specified low tolerance, the control module  70  operates to increase the transit rate of the tail support  26  and/or decrease the rotational rate of the axial body wires  14 . When the variance in the screen gauge comes within the specified tolerance or is within the specified tolerance, the control module operates to maintain the transit rate of the tail support  26  and/or rotational rate of the axial body wires  14 . The adjustments in transit rate and rotational rate can occur without stopping the rotation of the axial body wires  14  during the wrapping of the wrap wire  16  about the axial body wires  14 .  
      Utilizing inputs from the wrap wire dimensional analyzer  50 , the control module  70  increases, decreases, or maintains the transit rate of the tail support  26  and/or rotational rate of the axial body wires  14  to compensate for variances in wrap wire  16  width to maintain the desired screen gauge. If the measured wrap wire  16  width increases over the initial or specified wrap wire  16  width, the control module  70  operates to increase the transit rate of the tail support  26  and/or decrease the rotational rate of the axial body wires  14 . If the measured wrap wire  16  width decreases, the control module  70  operates to decrease the transit rate of the tail support  26  and/or increase the rotational rate of the axial body wires  14 . If the measured wrap wire  16  width does not depart from the initial or specified wrap wire  16  width, the control module  70  maintains the transit rate of the tail support  26  and the rotational rate of the axial body wires  14 . In an instance where a high and low wrap wire tolerance is an input to the control module  70 , the control module adjusts the transit rate of the tail support  26  to maintain the screen gauge within the specified tolerance. If a variance in the wrap wire  16  width exceeds a specified high tolerance, the control module  70  operates to decrease the transit rate of the tail support  26  and/or increase the rotational rate of the axial body wires  14 . If the variance in the wrap wire  16  width exceeds a specified low tolerance, the control module  70  operates to increase the transit rate of the tail support  26  and/or decrease the rotational rate of the axial body wires  14 . When the variance in the wrap wire  16  width comes within the specified tolerance or is within the specified tolerance, the control module operates to maintain the transit rate of the tail support  26  and rotational rate of the axial body wires  14 . The adjustments in transit rate and rotational rate can occur without stopping the rotation of the axial body wires  14  during the wrapping of the wrap wire  16  about the axial body wires  14 .  
      Using inputs from the wrap wire dimensional analyzer  50  and screen gauge analyzer  60 , the control module  70  operates the marking system  66  to mark the wire wrapped screen  12  as it is being constructed. The control module  70  marks the wire wrapped screen  12  when a measured variance exceeds a high or low marking tolerance. For example, if the screen gauge exceeds a high or low screen gauge marking tolerance, the control module operates the marking system  66  to mark the wire wrapped screen  12  substantially coinciding with the position of the measured variance on the constructed portion of the screen  12 . The wire wrapped screen  12  is marked during the wrapping of the wrap wire  16  about the axial body wires  14 , and the rotation of the axial body wires need not be stopped.  
      Data from the wrap wire dimensional analyzer system  50  and screen gauge analyzer system  60  is accessible to an operator through the displays  74 . The data can also be logged to a computer readable media  82 , and if desired, can be logged against a length of the wire wrapped screen  12  so that the position of variations in the measured dimensions can be easily correlated to the constructed wire wrapped screen  12 . On completion of the wrap wire screen  12  or at some time prior to completion, the logged data can be output to the printer  84 , saved to a removable media by the media drive  78 , or accessed remotely on a network, if the control module  70  coupled to a network.  
      If screen length is input to the control module  70 , the control module operates to cease production of the wire wrap screen  12  by stopping the power source  44 , the rotation of head  20  and tail chuck  28 , and movement of the tail support  26 . Thereafter, the wire wrapped screen  12  is removed from the wire wrapping system  10  and excess length of the axial body wires  14  removed.  
      The invention has many significant advantages. For example, by compensating for wrap wire width during construction of a wire wrapped screen, the screen gauge is more uniform and the tolerance of the gauge, tighter. Likewise, by monitoring the gauge during the construction of the wire wrapped screen, variances in screen gauge due to other influences than wrap wire width can be compensated for. At present, most wire wrapped screens meet a screen gauge tolerance of +0.001/−0.002 inches (0.001 over gauge and 0.002 under gauge). Utilizing the concepts described herein, the screen gauge tolerance can be tightened. For example, tolerances of +0.0005/−0.0001 or tighter can be achieved.  
      Another advantage is that fewer out of spec screens are obtained. Typically, if a screen is constructed that does not meet spec, and the defect cannot be corrected, the screen is discarded. By compensating for wrap wire width and variances in screen gauge during the construction of the wire wrapped screen, fewer, if any, screens are constructed that do not meet spec.  
      A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, although the illustrative wrap wire system described herein moves the wire wrapped screen being constructed along its longitudinal axis relative to the wrap wire feed assembly and welding arm, it is within the scope of the invention that the wrap wire feed assembly and welding arm be moved along the longitudinal axis of the wire wrapped screen being constructed. In such an instance, the transit rate of the wrap wire feed assembly and welding arm, rather than the transit rate of the wire wrapped screen, is adjusted in controling the screen gauge. Also, the wrap wire dimensional analyzer system and/or screen gauge analyzer system can be used apart from the control of the tail support transit rate and the head rotational rate. In such an instance, the measurement data concerning the wire wrapped screen is collected during the wire wrapping process without compensating for variance in the measured dimensions during the wire wrapping process. Accordingly, other embodiments are within the scope of the following claims.