Patent Publication Number: US-2012024031-A1

Title: Shape restoration metal rolling tool and method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present subject matter relates generally to a tool for restoring the shape of a deformed metal surface, such as a hand tool which may be used, for example, for auto body work, and a method for employing the tool. 
     2. Related Art 
     One form of metal shaping comprises working a deformed metal surface to restore a shape such as a continuous contour. One important example of this form of metal shaping is auto body repair work. Techniques for shaping metal surfaces are used to repair dents in auto bodies, for example, in auto fenders. A dent in a fender usually comprises a depression or a protuberance in a continuous contour of a fender. In order to repair the dent, the dent must be worked so that it is returned to a previous state as part of the continuous contour. A standard (as opposed to sub-standard) repair will take advantage of “memory” in the metal&#39;s crystalline structure in order to restore a fender to its prior contour. 
     A prevalent method of repairing dents is the hammer-and-dolly method of metal repair. A dolly is a hand tool usually comprising a shaped block of steel. It may be used as a hammer or an anvil. In the hammer-and-dolly method, a technician beats on a metal fender, for example, until the fender is restored to its proper shape. In the simplest form of this technique, the technician holds a dolly behind a surface to be worked. The technician hits the fender with the hammer, and the dolly acts as an anvil. The weight of the hammer, the shape of the hammerhead, and the shape of the dolly are all carefully selected to fit the desired shape of a repaired fender. A dolly with a pronounced radius is desirable for a rounded fender. A flatter dolly or the flatter side of a dolly is preferred for a flat quarter-panel or doorskin. The technician uses the hammer to flatten the metal against the dolly. 
     This technique gives the appearance of being simple and straightforward. However, a technician must accumulate years of experience in order to perform the technique properly. Inexperienced technicians using hammers and dollys inflict a great deal of damage on automobile bodies. The hammer generally causes tool marks. A common form of tool mark is an arcuate indentation left by an edge of a circular hammer head. A significant percentage of the repair time is often required simply in removing marks. Additionally, and significantly, repeated hard hitting of the sheet metal in a fender generally causes the undesirable effects of stretching, deforming, and warping the metal. 
     These undesirable effects are due to a phenomenon called work hardening. Work hardening is a permanent distortion of crystal structure caused by repeated plastic deformation of the metal. Working of the metal between a hammer and dolly constitutes plastic, rather than elastic, deformation. In addition to the effects already described, the metal loses its memory of a contour. 
     When this work hardening causes stretching, warping, and other deformation, additional work is necessary to complete an acceptable repair. A preferred process for helping the metal regain its original shape is heat shrinking. The metal is heated in order to allow steel molecules to move back into their original contour. A body hammer is often used to “fine tune” the shaping of a contour. Cooling the heated area shrinks the metal close to its original thickness. 
     Even this remedial work is ineffective in many cases. The metal cannot regain its original shape. Integrity of the metal structure may be destroyed, which can lead to eventual cracking within the affected area. Options at this point of the repair process are to accept a substandard repair, use Bondo® to give the appearance of a standard repair, or to replace the dented body component. 
     The extra operations required to complete the repair increase costs. Insurance companies do not wish to pay for additional work that could have been avoided, car owners do not want to have uninsured costs, and body shop owners do not want to see their profit margins decreased. 
     Undesired effects can be reduced by use of a technique in which a dolly is used to shape the area including a dent. Shaping is completed by hammering the surface “off-dolly,” i.e., without using the dolly as an anvil. However, successful employment of this technique requires a highly experienced technician. Even then, work hardening results. 
     In recent years, the difficulties described above have been compounded by advances in the construction of automobile bodies. For example, ten years ago, many cars had fenders that were made of steel ⅛″ thick. Today, some car models have body sections made of alloys other than steel. Body sections may be as thin as 1 mm. The different alloys utilized to make such sections strong demand precise repair methods. Distorted alloy panels have a low level of repairability compared to thicker steel panels. Also, today&#39;s body technicians must spend a significant portion of their time fixing the tool marks made from pushing a dent down or pulling a dent out. There is a need for a tool that will overcome the disadvantages of the prior art. 
     SUMMARY OF THE PRESENT SUBJECT MATTER 
     A tool assembly metal shaping, e.g., for auto body repair, includes a shaper and a tool manipulator which functions as a handle. The shaper, which is a subcombination of the assembly, comprises a roller on a transversely disposed axle. The shaper includes a roller which is mounted between opposite legs in a yoke member. 
     In a plane intersecting the axis, the roller has a curved surface with a central portion having a reduced curvature, and increased curvature between the central portion and lateral sides of the roller. Dimensions of the legs and the roller are selected such that the legs will not contact the metal when the curved surface of the roller is in contact with the metal surface being worked. Additionally, transverse ends of the roller are shaped so that a technician will feel a change in force reaction before the shaper pivots about a corner of the roller. 
     At one end, the shaper comprises means for securing the shaper to the tool manipulator. The shaper may be releasably secured to or unitary with the tool manipulator. In one form, the shaper receives a tapered end of a tool, for example, as a tire iron. The shaper is operated so that the roller engages the work surface to restore the metal to a desired contour. 
     A method for a roller constructed as described above is utilized in the context of, for example, auto body repair. For example the metal may be heated. Then the roller is applied against an area displaced from a surface contour. The roller is moved reciprocally, and force is applied against the dent to restore the metal to an original contour. The number of reciprocal motions required is generally a function of the depth of the dent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention are more particularly described with reference to the following drawings taken in connection with the following description. 
         FIG. 1  is an elevation of a tool assembly constructed in accordance with the present subject matter; 
         FIG. 2  is an exploded view of a shaper; 
         FIG. 3  is a cross-sectional view taken along the lines  3 - 3  of  FIG. 1  illustrating an alternative form of recess in the shaper; 
         FIG. 4 , consisting of  FIGS. 4(   a ),  4 ( b ), and  4 ( c ), illustrates alternatives for securing a shaper to a tool manipulator; 
         FIGS. 5 and 6  are diagrams illustrating the geometry of the roller; 
         FIG. 7  is partial perspective view of a Jaguar sedan having a dented rear quarter panel; 
         FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 7 ; 
         FIG. 9  illustrates a prevalent prior art form of body repair; and 
         FIGS. 10 through 14  illustrate a repair performed in accordance with the present subject matter. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments according to the present subject matter will help minimize creation of damage during the repair process and, in selected situations, allow previously unrepairable damaged panels to be repaired. Relatively inexperienced technicians have an increased chance of executing successful, efficient repairs. 
       FIG. 1  is an elevation of a tool assembly  1 . Among the applications of the tool assembly  1  are repairs on dents, high spots, creases, and crowns (the outward distortion surrounding a dent) on metal surfaces, typically auto bodies. The tool assembly  1  comprises a tool manipulator  10  and a shaper  12 . The tool manipulator  10  in the present illustration comprises a handle  14 . The handle  14  comprises a proximal end  13 . A grip  15  may be adjacent the proximal end  13 . A shaft  16  extends from the proximal end  13  to a distal end  19 . In one preferred form, a tapered tip  18  is located at the distal end  19 . The tool manipulator  10  may be releasably secured to the shaper  12  as further described below. 
     One form of tool manipulator  10  may comprise a pry bar such as a tire iron. In this case; the grip  15  may not be formed on the handle  14 . The shaper  12  may be designed to fit securely onto distal ends of most commonly used pry bars. A tool manipulator  10  having a selected length may be used for determining the linear displacement in a longitudinal direction of the shaper  12  from a proximal end  13  of the handle  14 . Many tool manipulators  10  can fit into one shaper  12 , irrespective of their lengths. This allows a technician to, in effect, have a whole set of tool assemblies  1  while needing only one shaper  12 . A longer shaft  16  will allow a technician to gain greater leverage than with a shorter shaft. The handle  14  comprises a fulcrum. The fulcrum is operated by one hand of a technician (not shown) closer to the proximal end  13 . The shaft  16  may pivot with respect to an other hand of the technician closer to the distal end  19 . However, the other hand of the technician will generally not comprise a fixed pivot point. 
     The shaper  12  is further described with respect to  FIGS. 2 and 3 .  FIG. 2  is an exploded axonometric view partially broken away, and  FIG. 3  is a cross-sectional view taken along the lines  3 - 3  of  FIG. 2 . The shaper  12  may comprise steel. Other materials could be used. However, many bodywork technicians prefer a body tool with weight comparable to steel rather than weight comparable to aluminum. 
     In the present illustration, the shaper  12  comprises a yoke  26 . The yoke  26  has a proximal end  20  and a distal end  22 . For the purpose of spatial reference, the degree of freedom in the direction from the proximal end  20  to the distal end  22  is called the longitudinal direction. A direction normal to the longitudinal direction is a transverse direction. A direction normal to the both the longitudinal direction and the transverse direction is a lateral direction. 
     The yoke  26  comprises a central body  28 , which may have a proximal end comprising the proximal end  20 . A first arm  32  and a second arm  34  each extend in a longitudinal direction from first and second longitudinal sides  36  and  38  of the central body  28 . 
     The first arm  32  and the second arm  34  need not be displaced by the same longitudinal distance as the first and second longitudinal sides  36  and  38 . In the present illustration, longitudinally inward portions of the first and second arms  32  and  34  are separated by a width W in the transverse direction. An inner surface  40  intermediate the first and second arms  32  and  34  is a distance H in the longitudinal direction from the distal end  22  of the yoke  26 . The transversely inward sides of the first and second arms  32  and  34  and the inner surface  40  define a recess  42 . 
     A shaft  50 , having an axis  52 , is mounted in the transverse direction. The shaft  50  is supported at opposite transverse sides thereof by the first and second arms  32  and  34 . The opposite ends of the shaft  50  may be press fit, welded, or otherwise secured to the first and second arms  32  and  34  respectively. A roller  54  is mounted for rotation about the shaft  50 . The roller  54  may be unitary with the shaft  50  if desired. The roller  54  has first and second lateral sides  55  and  56  for positioning adjacent the first and second arms  32  and  34  respectively. A shaping surface  58  is defined by an intersection of the roller  54  and a plane  60  intersecting the axis  52 . 
     It is generally desirable to form a radius at corners  62  and  64  defined by the intersection of the shaping surface  58  with the lateral sides  55  and  56  respectively. In this manner, the corners  62  and  64  will not comprise sharp edges which may leave undesired lines in a surface being worked. Alternatively, the corners  62  and  64  may be chamfered. In some applications, it may be desirable to provide a roller  54  comprising a right circular cylinder. 
     One material out of which to make the roller  54  is of stainless steel. Stainless steel does not pick up metal shavings and does not contaminate aluminum panels. The roller  54  may be either polished or unpolished. For use on steel, the roller  54  may be unpolished. It is preferable but not essential that the roller  54  be highly polished for use on aluminum. This construction will meet auto makers&#39; requirements for avoiding galvanic corrosion caused by the contact of dissimilar metals such as steel and aluminum. 
     The shaper  12  may be releasably secured to the manipulator  10  ( FIG. 1 ). However, a releasable connection is not essential. An aperture  70  extends in the lateral direction across the one surface of the shaper  12 . The aperture  70  communicates with a recess  72  having a longitudinal depth L in the central body  28 . The recess  72  has a depth D in the lateral direction. In the embodiment illustrated in  FIG. 2 , the recess  72  is substantially rectangular with each deep we are. A laterally extending aperture  73  communicates the recess  72  to an exterior of the yoke  26 . A set screw  74  is received in the aperture  73  for releasably securing the tip  18  ( FIG. 1 ) of the tool manipulator  10  to the shaper  12 . The set screw  74  is tightened against the tapered tip  18 . When it is desired to release the shaper  12  from the tool manipulator  10 , the set screw  74  is loosened. 
     In an alternative form, illustrated in  FIG. 3 , the recess  72  is tapered. The shape of the recess  72  is selected to receive an end of a preselected tool and to provide for a press fit. In the present illustration the preselected tool is the tool manipulator  10 . The recess  72  is shaped to receive the tip  18  ( FIG. 1 ). Applying longitudinal force to the shaper  12 , as by tapping on the shaper  12 , causes relative motion with the tapered tip  18  to provide are a releasable press fit. In use, the force applied from the tool manipulator  10  to the shaper  12  tends to keep the tip  18  in an engagement with the recess  72 . When it is desired to remove the shaper  12  from the tool manipulator  10 , angular movement of the tip  18  with respect to the shaper  12 , e.g. jiggling, may be used to create loosening. Alternatively, other forms of force could be applied to allow removal of the shaper  12  from the manipulator tool  10 . 
       FIG. 4 , consisting of  FIGS. 4(   a ),  4 ( b ), and  4 ( c ), illustrates additional forms of a tool assembly. In  FIG. 4(   a ), the tool manipulator  10  is unitary with the shaper  12 . In this embodiment, the shaper  12  is not movable from one handle  10  to another. 
     In an alternative embodiment illustrated in  FIG. 4(   b ), the tool manipulator  10  comprises a coupling member  116  at the distal end  19  thereof. The coupling member  116  may comprise a right circular cylinder. The recess  72  ( FIG. 2)  may be cylindrical in order to receive the coupling member  116 . In this embodiment, the shaper  12  is provided with a mating member  121  at the proximal end  22 . Many different forms coupling member  100  and mating member  121  may be provided. For example, the coupling member  116  may comprise one or more spring-loaded detents  122 , e.g., spring-loaded ball bearings. The detents  122  interact with stop means  124  to secure the shaper  12  to tool manipulator  10 . In the present illustration, the stop means  124  comprises an annular groove  126  surrounding the recess  72  and longitudinally displaced from the aperture  73 . As the coupling member  116  moves longitudinally into the recess  72 , the detents  122  engage a portion of the shaper  12  surrounding the aperture  73 . As the coupling member  116  continues to move, detents  122  moved radially into the coupling member  116  against spring bias until they are in longitudinal registration with the stop means  124 . At this point, the detents  122  snap into the stop means  124 , and the shaper  12  is secured to the tool manipulator  10 . 
       FIG. 4(   c ) partially illustrates a tool manipulator having an adjustable-length shaft  132 . The shaft may comprise first and second shaft members  135  and  136  which are axially slidable with respect to one another. The first and second shaft members  135  and  136  are maintained in a selected relative position in order to determine the length of the shaft  132 . In one form, the first and second shaft members  135  and  136  may have apertures  138  axially displaced therealong. The apertures  138  are positioned to be in transverse registration. Securing means  140  maintains the relative position of the first and second shaft members  135  and  136 . The securing means  140  may comprise a first nut  138  and bolt set  141 . A first bolt  142  passes through one selected pair of aligned apertures in the first and second shaft members  135  and  136  respectively. A first nut  143  is received on the first bolt  142  in order to compress the first and second shaft members  135  and  136  and maintain them in alignment. A second nut and bolt set  151  may be provided to secure the first and second shaft members  135  and  136  and to prevent rotation about the first nut and bolt set  141 . A second bolt  152  passes through one selected pair of aligned apertures  138  in the first and second shaft members  135  and  136  respectively. A first nut  143  is received on the first bolt  142  in order to compress the first and second shaft members  135  and  136  and maintain them in alignment. 
       FIG. 5  is a diagram comprising an elevation of a roller  54 . In one preferred form, the roller  54  comprises a solid of rotation about the axis  50 . However, in alternative forms, it may be possible to have discontinuities or inflection points in the shaping surface  58 . Therefore, the roller  54  may also be described as defining a cylindrical envelope  80 . 
       FIG. 6  is also an elevation of the roller  54 , used to further describe geometry of the roller  54  and of the shaping surface  58 . It is desirable to provide a shaping surface  58  which will push a dent back into a contour and which will not produce tool marks or lines in a surface being restored. 
     In one preferred form, a nominal transverse width for a roller  54  may be 1½″ or 40 mm. This width is an optimization for a nominal car fender repair. The width is wide enough to work a piece of metal and narrow enough to afford a technician a high degree of control. Additionally, the force applied by a technician is spread across the width of the roller  54 . Therefore, it is desirable to provide a concentration of force at the shaping surface  58  which is adequate to work a dent but which will not easily cause undesired deformation. It is desirable to have a shaping surface  58  wherein curvature increases toward outer transverse ends. If curvature is too extreme, the roller  54  will produce undesired deformation. 
     A circle  170  is illustrated in  FIG. 6  tangent to a portion of the shaping surface  58  having minimum curvature. The circle  170  has a reference origin  172 . A roller  54  having a circular shaping surface  58  with a reference origin  172  on the axis  50  would have a curvature that is too extreme, i.e., one that will produce undesired indentations. Therefore, curvature of the shaping surface  58  at a central portion is described as curvature less than that of a circle having a reference origin. This difference is most pronounced when the reference origin  172  is at the axis  50 . The term “curvature less than that of a circle having a reference origin” encompasses radii from a reference origin defining a shaping surface  58  that provides a reasonably distributed force gradient from a center of the shaping surface  58  to the transverse ends  55  and  56  thereof. “Reasonably” is a function of the dimensions of the roller  54  and the preselected material which a technician will be working. The shaping surface  58  will not have sufficient convexity to create depressions with respect to a fender contour. 
     The shaping surface  58  may be resolved into a central section  182  and first and second outer sections  184  and  186 . The central section  182  has a high point  183 , which is at a maximum radial distance from the axis  50 . The outer sections  184  and  186  extend between the central section  182  and the first and second, opposite transverse ends  55  and  56  of the roller  54  respectively. The sections  182 ,  184 , and  186  may be substantially equally wide. However, this is not necessary. Curvature increases from the high point  183  to the ends of the roller  54 . 
     The central section  182  may comprise a section with substantially constant curvature. A transition segment  188  connects one lateral end of the central section  182  ( FIG. 5 ) to the outer section  184 . A transition segment  190  connects an opposite lateral end of this central section  182  to the outer section  186 . The outer sections  184  and  186  may each have a second curvature. Alternatively, change in curvature from the high point  183  may change slope at other than a constant rate within each section  182 ,  184 , or  186 . In one nominal embodiment, the diameter of the roller  54  is 15 mm at the high point  183 , 14 mm at the transition segments  188  and  190 , and 12 mm at the first and second, opposite transverse ends  55  and  56  roller  54 . 
       FIG. 7  is partial perspective view taken from a lower rear corner of a Jaguar sedan  201  having a dented rear quarter panel  200 .  FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 7 . The rear quarter panel  200  has a contour  202  ( FIG. 8 ) with an outer surface  204  and an inner surface  206 . In the present illustration, a dent  210  extends inwardly from the outer surface  202 . A peak  216  on the dent  210  is a maximum distance from the contour  202 . The portion of the dent  210  adjacent the peak  216  is the high side  218 . The area of the dent  210  at the contour  202  is the low side  224 . Generally, a dent will have a crown  226  surrounding a low side of a dent projecting from and in a direction opposite to the direction of projection of the peak  216 . In the present illustration, the crown  226  surrounds a void in the contour  202  defined by the dent  210 . 
       FIG. 9  illustrates a prevalent prior art form of body repair. A technician  240  uses a dolly  250  and a hammer  260 . The technician may first use the dolly  250  to reduce the depth of the dent  210 . Subsequently, in one technique of working the dent  210 , the technician places the dolly  250  on the high side  218  and works the hammer  260  on the low side  224 . Alternatively, as seen in  FIG. 9 , the dolly  250  is placed on the low side  224  of the dent, and the hammer  260  knocks the high side  218  down onto the dolly  250 . The technician  240  flattens the crown  226  in a similar matter. Since the portion of the quarter panel  200  is sandwiched between the dolly  250  and the hammer  260 , the metal is subjected to repeated plastic deformation. Repeated plastic deformation causes work hardening. Additionally, tools marks result due to impact of a hammer face  262  at a perimeter  264 . 
       FIGS. 10 through 14  illustrate a repair performed with the present subject matter. Referring to  FIG. 10 , a partially illustrated rear quarter panel  300  has a contour  302  with an outer surface  304  and an inner surface  306 . In the present illustration, a dent  310  extends inwardly from the outer surface  304 . A peak  316  on the dent  310  is a maximum distance from the contour  302 . The portion of the dent  310  adjacent the peak  316  is the high side  318 . The area  320  of the dent  310  at the contour  302  is the low side  334 . A crown  326  surrounds a void in the contour  302  defined by the dent  310 . The tool assembly  1  ( FIG. 12 ) may be used effectively on thin metal alloy body parts which do not respond well to hammering. 
     In one form, the work area is heated to approximately 250° to 300° F., as with a torch  338 . The shaper  12  is may be applied to a heated fender. This system minimizes or eliminates creation of tool marks in the metal during a repair. The common disadvantage of prior art methods is that they require expenditures of time and effort to remove tool marks placed in the metal during repairs. Since the present subject matter utilizes a roller, creation of tools marks is minimized. 
     Prior to use of the tool  12 , the operation of  FIG. 11  may be performed in which a padded impact tool  342  may be used to reduce the height of the dent  310 . 
     Prior to use of the shaper  12 , the dent  310  may be heated to approximately 250° to 300° F. The technician  240  ( FIG. 9 ) then grasps the tool assembly  1 , for example, by the grip  5  ( FIGS. 1 and 2 ). As seen in  FIG. 12 , the shaper  12  is moved to engage the dent  310 . The roller  54  may be placed against the high side  318  and worked against the dent  310 . The strength of an average technician  340  is sufficient to work the dent  310  back into the contour  302 . Similarly, the technician  340  uses the shaper  12  to return the crown  326  into the contour  302 . Use of the shaper  12  provides superior results to those obtained by hammering. As illustrated in  FIG. 13 , the technician  240  moves the shaper  12  in a reciprocal motion applying force to successive rectangular areas of the dent  310 . The shaper  12  is worked from the high point toward the contour  302 . Similarly, the shaper  12  may be employed on the crown  326 . 
     Shaping of the dent  310  back into the original contour  302  is aided by the molecular structure of the metal within the quarter panel  300  which provides a degree of shape memory. Because the dent  310  is not subjected to plastic deformation, the memory characteristic is not lost. 
     The present subject matter will also provide a convenience for technicians. Technicians will often want to grab the nearest tool in order to accomplish a certain task. When a commonly utilized tool is employed as the tool manipulator  10 , the tool assembly  1  can be used for common tasks. These tools may be used for frequently performed functions such as patching tires, applying tape seam sealer, repairing bumpers, gluing upholstery, and even for use in rolling into place auto mats or even kitchen tiles. Embodiments of the present subject matter have been utilized successfully in virtually all categories of auto body repair. 
     The previous description of some aspects is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the spirit or scope of the invention. For example, one or more elements can be rearranged and/or combined, or additional elements may be added. Thus, the present invention is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.