Abstract:
An apparatus and method for separating welded multi-layered samples has a slotted engine-driven spindle that twists and pulls a layer from the sample, breaking the welds as the layer winds around the spindle. The sample is held between two clamps and a tensioning cylinder pulls a movable first clamp against the second stationery clamp. Sensors may sense the force required to break the welds and the data may be stored and analyzed in a computer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/994,181, filed May 16, 2014, entitled, Peeling Apparatus and Methods for Separating Welded Layers, which is incorporated by reference herein in its entirety for all purposes. 
    
    
     FIELD 
     The present invention relates to weld testing apparatus, and more particularly, to apparatus for destructive testing of welds. 
     BACKGROUND 
     Methods and apparatus are known for peel testing welded panels for quality assurance. These assessments is typically done through manual means which can vary in technique and efficiency from operator to operator. For example, AWS C1.1 illustrates peeling welded layers from one another using manually wielded pincers or a hammer and chisel. The results obtained are technique dependent and frequently produces separated panels that are highly distorted. In addition, manual methods may be both strenuous and slow. Alternative methods and apparatus for peel testing therefore remain desirable. 
     SUMMARY 
     The disclosed subject matter relates to a device for separating a first layer from a second layer conjoined to form a member. The device has: a base structure, a first clamp mounted on the base structure capable of retaining a first portion of the member including the first layer and the second layer therein, a second clamp mounted on the base structure at a distance from the first clamp approximating at least a portion of a length of the member and capable of retaining a second portion of the member including the first layer therein, a rotatable spindle having a slot therein capable of receiving a portion of the second layer at a position intermediate the first clamp and the second clamp and twisting the first layer around the spindle when the spindle is rotated and while the first layer is clamped by the first clamp and the second clamp to separate the second layer from the first layer. 
     In another embodiment, a member is coupled to the spindle and is capable of applying torque to the spindle. 
     In another embodiment, the member is a pulley. 
     In another embodiment, the pulley is a sprocket. 
     In another embodiment, the pulley is a gear. 
     In another embodiment, the member is a bar. 
     In another embodiment, the second clamp is movable and further includes a tensioner capable of applying tension to the member. 
     In another embodiment, the tensioner is hydraulically actuated. 
     In another embodiment, further including a slide and wherein the second clamp is mounted on the slide and capable of sliding on the slide in response to the application of tension by the tensioner. 
     In another embodiment, further including a spindle mount capable of rotatably supporting the spindle and a spindle slide capable of slidably supporting the spindle mount between a first position proximate the second clamp and a second position proximate the first clamp. 
     In another embodiment, further including an engine capable of turning the pulley. 
     In another embodiment, the pulley is a first pulley and further including a second pulley coupled to the engine and a drive connection extending between the first pulley and the second pulley, the first and second pulleys and drive connection providing a torque advantage for the engine to turn the spindle. 
     In another embodiment, further including a transducer capable of measuring energy expended in separating the second layer from the first layer of the member. 
     In another embodiment, further including a transducer capable of measuring tension experienced by the member as the second layer is separated from the member. 
     In another embodiment, further including a transducer capable of measuring force exerted by the spindle as the second layer is separated from the member for generating force data and a computer capable of receiving and storing the force data. 
     In another embodiment, further including a transducer capable of sensing a position of the spindle relative to the member and generating position data, the computer capable of correlating the force data and the position data. 
     In another embodiment, a method for separating a first layer from a second layer conjoined to form a member, includes: separating an end of the first layer from the second layer to form a separated end of the first layer and a separated end of the second layer; securing the separated end of the first layer of the member in a first clamp; securing the member at a position distal to the separated end of the first layer in a second clamp; inserting the separated end of the second layer into a slot of a spindle; turning the spindle and twisting the second layer around the spindle to separate the second layer from the first layer. 
     In another embodiment, further including the step of applying tension to the first layer prior to the step of turning. 
     In another embodiment, the step of applying tension is conducted by pulling the first clamp away from the second clamp. 
     In another embodiment, the first layer and the second layer are conjoined by a least one weld and the step of separating includes breaking the at least one weld. 
     In another embodiment, further including measuring the force required to separate the first layer from the second layer during the step of turning. 
     In another embodiment, further including the step of measuring bonding artifacts after the step of twisting. 
     In another embodiment, when the step of measuring is by image analysis. 
     In another embodiment, further including the step of straightening the member after the step of twisting and before the step of measuring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure, reference is made to the following detailed description of exemplary embodiments considered in conjunction with the accompanying drawings. 
         FIG. 1  is front perspective view of a peeling tool in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a diagrammatic view of a split spindle of the peeling tool of  FIG. 1  in three stages of delaminating a pair of conjoined sheets. 
         FIG. 3  is a front perspective view of the peeling tool of  FIG. 1  as it approaches a state of completion of the peeling function. 
         FIG. 4  is a rear perspective view of a peeler sub-assembly of the peeling tool of  FIG. 1 . 
         FIG. 5  is a perspective view of a first of a pair of conjoined sheets after delamination. 
         FIG. 6  is a perspective view of a second of a pair of conjoined sheets after delamination. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Manual peel testing, which results in a highly distorted separated panels typically requires the artifacts of the joints thereof, e.g., spot weld “buttons” or holes to be measured by hand, e.g., with a set of calipers or micrometers. An aspect of the present disclosure is the recognition that peel testing of welded panels that yields a less distorted panel may allow the panels and welds to be analyzed automatically. In a similar vein, the present disclosure recognizes that straightening a distorted panel may facilitate automatic inspection. For example, a flat or flattened panel may be amenable to imaging and imaging analysis as disclosed in a U.S. patent application Ser. No. 14/702,204, filed May 1, 2015, entitled Apparatus and Methods for Weld Measurement, owned by the Assignee of the present application and incorporated in its entirety herein by reference. In another aspect of the present disclosure, the peel apparatus and method thereof may yield more consistent results than conventional methods and saves significant manual labor. 
       FIG. 1  shows a peeling tool  10  with a base frame  12  having a center portion  12 C and left and right portions  12 L and  12 R. The right portion  12 R supports a right clamping platform  14  to which one or more clamp plates  16 A,  16 B may be attached by one or more bolts  18 . A laminate sample  20  having layers  20 A,  20 B conjoined by welding, e.g., spot welds  20 W (two of which are diagrammatically shown in dotted lines—any number or pattern being possible), may be inserted between the clamp plates  16 A,  16 B (or between a clamp plate  16 A and the right clamping platform  14 ) at one end thereof and the bolts  18  tightened to firmly hold the sample  20  in association with the clamping platform  14  attached to the right portion  12 R of the frame  12 . While a threaded clamping mechanism is shown, a hydraulic or pneumatic cylinder could be used to exert clamping force on the sample  20  at the clamping platform  14 . The frame  12  may be made of cast iron or fabricated of steel plate or another strong material capable of withstanding the forces generated by the peeling tool  10 . The center portion  12 C of the frame  12  supports a slide way  22  upon which a peeler  24  and a movable clamping platform  26  independently slide. The movable clamping platform  26  supports one or more clamp plates  28 A,  28 B that may be secured to the movable clamping platform  26  by bolts  18  that clamp the other (left) end of the sample  20  onto the movable clamping platform  26 . As with clamping platform  14 , hydraulic or pneumatic clamping mechanisms may be used at movable clamping platform  26 . The left portion  12 L of the frame  12  supports a hydraulic cylinder  28  with a piston rod  28 P that attaches to the movable clamping platform  26 , e.g., via a through pin. The hydraulic cylinder may be actuated by pressurized hydraulic fluid supplied/withdrawn by hydraulic lines  28 A,  28 B to pull the piston rod  28 P and the coupled movable clamping platform  26  along the slide way  22  in a tensioning direction T to apply tension to the sample  20 , the other end of the sample  20  being clamped to the clamping platform  14  that is rigidly held to the frame  12 . Prior to clamping the sample  20  to the movable clamping platform  26 , a tab portion  20 T of one of the layers  20 B, i.e., the lower layer, is bent down at an angle relative to the remainder of the sample  20  and threaded into a slot  30 S in spindle  30  of the peeler  24 . As a result, only the upper layer  20 A of the sample  20  is held in tension between the clamping platforms  14  and  26 , the tab  20 T of the lower layer  20 B being inserted into the spindle slot  30 S rather than being clamped to the movable clamping platform  26 . The peeler  24  is capable, as described more fully below, of turning the spindle  30 , such that tab portion  20 T inserted into the slot  30 S is rotated by the spindle  30  and causes the lower layer  20 B to wind about the exterior of the spindle  30 . As the spindle  30  progressively winds the lower layer  20 B around the spindle  30 , a greater length of the lower layer  20 B is pulled away from the upper layer  20 A. When a bonded area, e.g., a spot weld that conjoins the layers  20 A,  20 B is encountered, the pulling force exerted by the turning spindle  30  tears the bond apart, which may result in the weld material of the bond being retained on one, the other, or both of the separated layers  20 A,  20 B. One or both layers  20 A,  20 B and the artifacts of the destroyed bond/weld  20 W, e.g., a weld “button,” hole or depression, may then be examined for dimensions and properties. 
       FIG. 2  schematically depicts the peeling of the lower layer  20 B from the upper layer  20 A that is clamped at both ends by clamping forces C 1 , C 2 , C 3 , C 4  and then pulled into tension by forces T 1 , T 2 . The tab portion  20 T of the lower layer  20 B is threaded into slot  30 S at position P 1 . As the spindle  30  is rotated in the direction of the arrows, it progressively winds more of the layer  20 B about itself, tearing/delaminating it from layer  20 A. Because the peeler  24  is free to slide on slide way  22 , as the spindle  30  rotates, winding and peeling layer  20 B, the spindle  30  pulls peeler  24  along the slide way, e.g., to positions P 2  and P 3 , as it tears the layer  20 B from  20 A. Layer  20 A remains stretched between clamping platforms  14  and  26  until removed by releasing it from the clamping platforms  14  and  26 . A transducer  31 , such as a strain gauge positioned intermediate the hydraulic cylinder and the clamping platform  26 , where it is subjected to tension force T 1 , may be monitored by a computer  33  or a data capture device, such that the forces encountered as the peeling tool  10  breaks the welds  20 W or other joints bonding layers  20 A,  20 B may be recorded and analyzed. In another alternative, the transducer  31  may be a hydraulic pressure transducer communicating with the hydraulic fluid, e.g., in line  28 B, that exerts the tensioning force T 1  and therefore will reflect changing levels of tension T 1  as the bonds between layers  20 A,  20 B are broken. In another alternative, a second or substitute transducer  35  sensing either mechanical strain exerted by the spindle  30  or force exerted by the motor  46  (see  FIG. 4 ) that turns the spindle  30  may be employed to sense bond breaking force that is recorded and analyzed by computer  33 . In the case of a hydraulic motor  46 , the varying pressure encountered within the hydraulic motor or the hydraulic pressure line that moves it may be monitored over time by a hydraulic pressure sensor. An electric motor  46  may be monitored by a transducer  35  that measures the electric power used by the motor  46  as the layers  20 A,  20 B are separated. The position of the peeler  24  may also be sensed by a transducer  37  and the position recorded in computer  33 . The force and position data recorded over time may be correlated to identify the force required to break a given weld  20 W or set of welds  20 W, which have a known position relative to the traversal path of the peeler  24 . Alternatively, force peaks may be used to identify the force required to break welds  20 W or sets thereof. 
       FIG. 2  also shows a simplified embodiment of the present disclosure. While the other embodiments illustrated utilize automated means for turning the spindle  30 , a bar or handle  36  could be attached to the spindle  30  to provide a torque arm TA 1  for turning the spindle  30 , winding layer  20 B and separating it from layer  20 A. The bar  36  may be in the form of a crank to facilitate turning manually. In the case of a manually turned bar  36 , the spindle  30  and bar  36  may or may not be mounted to the slide way  22 , as further described below. 
       FIG. 3  shows the peeling tool  10  as it approaches a state of completion of the peeling/delaminating function. More particularly, almost the entire lower layer  20 B is wound around the spindle  30  of the peeler  24  breaking all welds  20 W that previously conjoined the layers  20 A,  20 B. Artifacts A 1  on the upper side of layer  20 A can be observed at locations where each weld  20 W previously existed. The artifacts, may be depressions where the weld  20 W was pulled downwards by the peeler  24  or may be holes, depending upon the nature of the weld  20 W and the way in which the specimen  20  was loaded into the peeling tool  10 . In  FIG. 3 , the peeler  24  has pulled itself from its initial position proximate clamping platform  26  to stationary clamping platform  16 , riding on slide  22 . Once having reached a state of completing delamination of layer  20 A and  20 B, the layers  20 A,  20 B may be removed from the peeling tool  10  for inspection and analysis.  FIG. 3  illustrates a condition in which the tension on the layer  20 A has been relaxed, .i.e., by depressurizing hydraulic cylinder  28 , allowing the sample  20  to be removed from the clamping platforms  14 ,  26  for examination. 
       FIG. 4  shows is a rear perspective view of a peeler sub-assembly  24 S of the peeling tool  10  of  FIG. 1 . The peeler subassembly has a housing  40  that rotatably supports a pulley  42  that drives spindle  30 . The housing also supports a motor  46 , e.g., a high torque electric or hydraulic motor that is bolted to the housing  40  via a flange (not shown). The motor  46  drives a pulley  44  aligned with pulley  42  via a belt  48  which extends there between, the radius of the pulley  42  providing a torque arm TA 2  to facilitate rotation of the spindle  30 . The pulleys  42 ,  44  may be in the form of sprockets and the belt  48  in the form of a drive chain. Alternatively, the pulleys  42 ,  44  could be replaced by intermeshing gears or a gear train that provides a suitable torque advantage between the motor  46  and the driven spindle  30 . An idler  50  may be employed to maintain tension in the drive belt/chain  48 . The housing  40  with attached motor  46 , drive and driven pulleys  42 ,  44  and spindle  30  is attached to a tracking base  52  that rides on the slide way  22 , e.g., on ball or roller bearings or simply a greased slot complementarily shaped to engage the slide way  22 . One or the other of the pulleys  42 ,  44  may be coupled to a handle or crank that allows manually turning the spindle  30 . 
       FIG. 5  shows a portion of the upper layer  20 A after it has been delaminated from the specimen  20  and removed from the peeling tool  10 . The bottom surface  20 AB of the top layer  20 A shows a plurality of artifacts A 2 , which may be raised weld “buttons” or depressed holes disposed on the remainder  20 AR of the surface  20 AB. These artifacts may be measured manually or automatically, e.g., as described in the application entitled, Apparatus and Methods for Weld Measurement which is incorporated herein by reference above. Because the upper layer  20 A is stretched between the clamping platforms  14  and  16  under tension during peeling/delaminating, the delaminated layer  20 A remains relatively straight during and after the peeling/delaminating process. This conformation of the delaminated layer  20 A promotes ease of examination, either manually or automatically. In one alternative, the delaminated layer  20 A may be further straightened, e.g., by pressing between the flat plates of a press or running it through a set of rollers. To avoid disturbing/deforming the artifacts A 2 , the rollers and or plates may be rubber or rubberized, or a rubber mat may be used to cover them when the delaminated layer  20 A is flattened. Straightening the delaminated layer  20 A into a generally planar configuration aids in automatic measurement/analysis, e.g., using vision systems and or image analysis. 
       FIG. 6  shows the lower layer  20 B after it has been delaminated by wrapping around the spindle  30 . The tab portion  20 T that is received in the slot  30 S of the spindle  30  is disposed towards the center of the coiled lower layer  20 B. A plurality of weld artifacts A 3  are disposed over the remainder of the surface  20 BR. If desired, the coiled lower layer  20 B could be uncoiled and/or flattened for analysis/measurement of the artifacts A 3 . 
     It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the claimed subject matter. For example, while the present disclosure has referred to panels joined by resistance spot welds as examples, the same apparatus and methods may be used to separate panels joined by other welding processes such as fusion (GMAW, laser beam, examples, panels fastened by other methods, such as friction stir (spot, stitch, swing and friction bit joining), and mechanical fastening (self-pierce riveting, conventional riveting and use of threaded fasteners, clinching, flow drill screws, etc. or adherence by adhesives or solders). While the embodiments shown utilize clamping platforms  14 ,  26 , using bolts for applying clamping pressure, a hydraulic, magnetic or pneumatically actuated clamp or a vice-like clamp could readily be employed. All such variations and modifications are intended to be included within the scope of the present disclosure.