Patent Publication Number: US-2006016240-A1

Title: Sheet metal repair support device and jig thereof

Description:
TECHNICAL FIELD  
      The present invention relates to a sheet metal repair support device and, more specifically, to a device for supporting the sheet metal operation of drawing out a damaged part to the normal position and a jig thereof.  
     BACKGROUND ART  
      As a device for drawing out a damaged part, there is known, for example, a sheet metal working instrument which draws out a damaged part using a panel surface around the damaged part as a fulcrum (see, for example, JP 10-250535 A).  
      More specifically, the instrument is equipped with a rail extending over the damaged part, a pulling portion (puller) slidably suspended from this rail, a leg portion frame slidable in the longitudinal direction of the rail, leg parts respectively extending toward the panel surface from one end of the leg frame and of the rail, and suction pads provided at the distal ends of the leg parts.  
      Further, in drawing out the damaged part, the suction pads are first fixed to the panel surface around the damaged part, and then the pulling portion is arranged over the damaged part. Subsequently, a washer is welded to the damaged part, and the distal end of the pulling portion is connected to this washer. Then, in this state, the pulling portion is operated to draw out the damaged part to the normal position using the panel surface, to which the suction pads are fixed, as a fulcrum.  
      Incidentally, after careful study, the present inventors have found out various points in need of improvement regarding the sheet metal operation using a sheet metal working instrument of this type.  
      First, when drawing out the damaged part, a large reaction force is applied to the panel surface through the leg parts. This reaction force is applied perpendicularly to the panel surface. Thus, when the panel surface serving as the place where the leg parts are fixed has a shortage of rigidity, a secondary damage such as distortion is generated in the panel surface due to this reaction force.  
      Further, in the prior art, in order to avoid such secondary damage, the rigidity of the panel surface, the arrangement of the leg parts, etc. are sufficiently examined before starting the operation of drawing out the damaged part. However, the rigidity of the panel surface, the appropriateness in the arrangement of the leg parts, etc. are not to be easily judged at a glance, and an appropriate arrangement of the leg parts requires great skill and years of experience. Thus, when an unskilled operator performs the operation, there is a fear of causing a secondary damage due to the reaction force of the leg parts as stated above.  
      Further, to draw out the damaged part efficiently, it is necessary to draw out the damaged part in a circle from outside the damaged part toward the center of the damaged part. In this regard, in the conventional sheet metal working instrument, in which the moving direction (movable direction) of the pulling portion is restricted to a straight line along the rail, so that it is impossible to realize diverse drawing operations such as one in a circle.  
      The present invention has been made in view of the background as described above. It is an object of the present invention to provide a sheet metal repair support device capable of suppressing a secondary damage to the panel surface due to the drawing of the damaged part. Further, the present invention aims to provide a sheet metal repair support device having a satisfactory operability and adaptable also to diverse drawing orders.  
     DISCLOSURE OF THE INVENTION  
      The present invention provides a sheet metal repair support device including a drawing device for drawing out a damaged part, and a plurality of leg parts fixed to a panel surface around the damaged part, the sheet metal repair support device being adopted, when drawing out the damaged part, to draw out the damaged part by using the leg parts fixed to the panel surface as fulcrums, characterized in that the leg parts are connected to the drawing device at angles providing predetermined inclinations with respect to normal lines extending from the panel surface constituting a fixation place.  
      In the present invention constructed as described above, the leg parts are connected to the drawing device at angles providing predetermined inclinations with respect to the normal lines extending from the panel surface where the leg parts are fixed, supporting the drawing device over the damaged part. Thus, part of the reaction force in the vertical direction applied to the panel surface when the damaged part is drawn out is transmitted to the panel surface while dispersed in other directions due to the inclined arrangement of the leg parts. Thus, the reaction force in the vertical direction applied to the panel surface is reduced, whereby generation of a secondary damage due to this reaction force is suppressed.  
      Further, it is desirable for the inclinations of the leg parts be set within a range in which the damaged part to be drawn out and the leg parts make acute angles. When the inclinations are set within this range, the leg parts are arranged so as to be widened out with respect to the drawing device, and the reaction force acting on the leg parts is scattered to the outside of the damaged part. Thus, it is possible to avoid generation of a secondary damage more reliably.  
      Further, each of the leg parts may be swingably supported with respect to the drawing device. In this construction, in which the leg parts are swingably supported with respect to the drawing device, so that, even if the panel surface, to which the leg parts are fixed, has an undulation, it is possible to arrange the leg parts at angles adapted to the undulation.  
      Further, each of the leg parts may be provided with a movable portion varying an angle at which the distal end of the leg part is held in contact with the panel surface. In this construction, even if the panel surface, to which the leg parts are fixed, is inclined, the inclination is absorbed by the movable portions provided on the leg parts, so that the relative inclination of the leg parts and the panel surface is corrected. Thus, it is possible to fix the leg parts to the panel surface at proper angles.  
      Further, it is possible to adopt a construction further including a set of sub frames supported over the damaged part through the leg parts, and a main frame supporting the drawing device so as to allow sliding in a longitudinal direction of the main frame, in which the main frame is connected to the sub frames through a frame bracket slidable with respect to an axial direction of the sub frames.  
      In this construction, the drawing device is slidable in the axial direction of the main frame, and the main frame is slidable in the axial direction of the sub frames. That is, the drawing device is movable over the damaged part in plane-matrix directions. Thus, it is possible to draw out the different portions of the damaged part in an appropriate order.  
      Further, the frame bracket may be equipped with a movable portion rotatable circumferentially around the main frame, and the main frame and the sub frames may be connected to each other through the movable portion.  
      In this construction, the movable portion rotating around the main frame is incorporated into the frame bracket, and the sub frames and the main frame are connected to each other through the movable portion. Thus, it is possible to appropriately change the relative angle of the main frame and the sub frames by means of this movable portion.  
      Further, the frame bracket may be constructed such that it detachably holds at least one of the main frame and the sub frames. In this construction, it is possible to perform operation with the sub frames and the main frame separated.  
      Further, the leg parts may each be equipped with a suction pad for fixation to the panel surface by a suction force, and the sub frames may be formed as hollow components, with a negative pressure generating the suction force of the suction pad being supplied to the suction pad through the hollow sub frames. In this construction, in which the negative pressure is supplied to the suction pad through the sub frames, it is possible to simplify the routing structure for negative pressure pipes, etc.  
      Further, in the present invention, in addition to the above-described sheet metal repair support device, the following jig also helps to support sheet metal repair.  
      That is, the present invention provides a jig for a sheet metal repair support device including a drawing device for drawing out a damaged part, and a plurality of leg parts fixed to a panel surface around the damaged part, the sheet metal repair support device being adopted, when drawing out the damaged part, to draw out the damaged part by using the leg parts fixed to the panel surface as fulcrums, characterized in that the jig is equipped with a base plate portion fixed to a periphery of the damaged part, and a fixation plate forming in a vicinity of the leg parts of the sheet metal repair support device a fixation plate serving as the panel surface constituting a proper fixation place using the base plate portion as a fulcrum.  
      Further, an angle adjusting mechanism for adjusting a support angle of the fixation plate with respect to the base plate portion may be provided between the base plate portion and the fixation plate.  
      Further, at least one of the base plate portion and the fixation plate may be provided with a slide mechanism supporting the fixation plate slidably with respect to the base plate portion.  
      As described above, in accordance with the present invention, it is possible to provide a sheet metal repair support device capable of suppressing a secondary damage of the panel surface due to the drawing out of a damaged part. Further, it is possible to provide a sheet metal repair support device having a satisfactory operability and adaptable to diverse drawing orders. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a diagram schematically showing the construction of a sheet metal repair support device according to an embodiment of the present invention.  
       FIG. 2  is a plan view of the sheet metal repair support device according to the embodiment.  
       FIG. 3  is a side view of the sheet metal repair support device according to the embodiment.  
       FIG. 4  is a front view of the sheet metal repair support device according to the embodiment.  
       FIG. 5  is a diagram schematically showing the construction of a drawing device according to the embodiment.  
       FIG. 6  is a diagram showing how operation is performed by using the sheet metal repair support device according to the embodiment.  
       FIG. 7  is a diagram showing how the sheet metal repair support device according to the embodiment is installed on a vehicle by using a jig.  
       FIG. 8  is a front view of the jig according to the embodiment.  
       FIG. 9  is a side view of the jig according to the embodiment.  
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      In the following, a preferred embodiment of the present invention will be described with reference to the drawings.  
      A sheet metal repair support device  1  according to this embodiment is equipped with a main frame  10  extending over a damaged part D, sub frames  20  connected to the main frame  10 , a plurality of leg parts  70  fixed to a panel surface P around the damaged part and supporting the main frame  10  and the sub frames  20  over the damaged part by using the panel surface P as a fulcrum, and a drawing device  40  used to draw out the damaged part.  
      The main frame  10  is composed of two steel pipes arranged in parallel. The parallelism of the steel pipes is maintained by a set of brackets.  
      One bracket  50  (the left-hand side bracket in  FIG. 1 ) retains one end of the main frame  10 . Further, the bracket  50  is provided with a rotation mechanism which rotatably connects the sub frame  20  ( 20   a ) described later with respect to the main frame  10  by using the main frame  10  as a rotation axis.  
      The other bracket  60  (the right-hand side bracket in  FIG. 1 ) connects the sub frame  20  ( 20   b ) to the main frame  10  and is equipped with a slide mechanism slidably supporting the steel pipes constituting the main frame  10  in the axial direction. Further, it is equipped with an attachment/detachment mechanism detachably retaining the main frame  10  with respect to the sub frame  20   b.    
      In this way, of one set of brackets, one bracket  50  is fixed to one end of the main frame  10 , and the other bracket  60  is provided so as to be longitudinally slidable using the main frame  10  as an axis. Thus, by moving the other bracket  60  toward or away from one bracket  50 , the distance between the sub frames  20   a ,  20   b  is changed, so that the distance between the leg parts  70  can also be changed.  
      In the following, one bracket  50  will be referred to as “the stationary bracket  50 ”. The other bracket  60  will be referred to as “the slide bracket  60 ”.  
      The sub frames  20  are formed by a pair of hollow steel pipes connected to the main frame  10  through the intermediation of the stationary bracket  50  or the slide bracket  60 .  
      In the following, based on the details on the brackets  50 ,  60 , the way the sub frames  20   a ,  20   b  and the main frame  10  are connected will be described.  
       FIG. 2  shows in detail how the sub frame  20   a  and the main frame  10  are connected on the stationary bracket  50  side.  
      As stated above, the stationary bracket  50  is provided with a rotation mechanism rotatably supporting the sub frame  20   a  using the main frame  10  as an axis. This rotation mechanism is incorporated into the stationary bracket  50 .  
      The stationary bracket  50  is equipped with a main block  51  fixed to one end of the main frame  10 , a rotation shaft  52  extending from the main block  51 , and an auxiliary block  53  retaining the sub frame  20   a  so as to allow it to slide in a direction perpendicular to the main frame  10 . Further, a bearing is formed in the auxiliary block  53 , and the rotation shaft  52  is incorporated into the bearing of the auxiliary block  53 .  
      That is, the auxiliary block  53  is rotatable relative to the rotation shaft  52  extending from the main block  51 , and the sub frame  20   a  is rotatable relative to the main frame  10  by being connected to the main frame  10  through the intermediation of the auxiliary block  53 . Further, in this embodiment, the above mechanism forms the movable portion of the frame bracket of the present invention.  
      Subsequently, the way the sub frame  20   b  and the main frame  10  are connected on the slide bracket  60  side will be described with reference to  FIGS. 2 and 3 .  
      As stated above, the slide bracket  60  is equipped with an attachment/detachment mechanism connecting the main frame  10  detachably to the sub frame  20   b . This attachment/detachment mechanism is formed by various components incorporated into the slide bracket  60 .  
      The slide bracket  60  is equipped with a main block  61  slidable in the axial direction of the main frame  10  and retaining the sub frame  20  in a direction perpendicular to the main frame  10 , and a fastening member  62  collectively fastening the main block  61  and the main frame  10  (steel pipes).  
      By releasing the fastening member  62 , the main frame  10  can be easily detached from the main block  61 . Further, when the fastening member  62  is released, the main frame  10  can rotate away from the damaged part, using the stationary bracket  50  as a fulcrum as shown in  FIG. 4 . When the fastening member  62  is closed, and the main frame  10  is connected to the main block  61 , it is possible to maintain the main frame  10  and the sub frames  20  in the state in which they are connected together.  
      Subsequently, the leg parts  70  will be described.  
      As shown in  FIG. 3 , the leg parts  70  have at the lower ends thereof suction pads  72  through the intermediation of universal joints  71  (movable portions), and are fixed to the panel P constituting the place of fixation by the suction force of the suction pads  72 .  
      Further, connected to each suction pad  72  is a negative pressure hose  73  for supplying negative pressure (see  FIG. 1 ). In this embodiment, in routing the negative pressure hoses  73 , the negative pressure hoses  73  are connected to the suction pads  72  through the sub frames  20 .  
      Further, the leg parts  70  are connected to the sub frames  20  through the intermediation of leg part brackets  80 . Each leg part bracket  80  is equipped with a bracket main body  81  slidable in the axial direction of the sub frame  20  and rotatable in the circumferential direction of the sub frame  20  using it as an axis, an angle setting lock mechanism  82  for fixing the bracket main body  81  to the sub frame  20  at an appropriate position and angle, and a height setting lock mechanism  83  for fixing the position of the leg part  30  with respect to the bracket main body  81  at an appropriate position (height).  
      By operating the lock mechanisms  82 ,  83 , positioning is effected on the leg parts  70  with respect to the sub frames  20 , whereby the support angles and heights of the leg parts  70  with respect to the sub frames  20  and the distance (span) between the leg parts  70  are determined. In this embodiment, there are provided two leg parts for each sub frame  20 , i.e., four leg parts  70  in total for the entire sheet metal repair support device  1 .  
      Subsequently, a drawing device  40  will be described.  
      As shown in  FIGS. 1 and 5 , the drawing device  40  is equipped with a main body portion  41  supported so as to be slidable in the axial direction of the main frame  10 , a draw-out rod  42  extending through the main body portion  41 , a ratchet lever  43  which draws out the draw-out rod  42  to the exterior of the main body portion  41  through a gear  42   a  formed on the side surface of the draw-out rod  42 , an electrodeposition portion  44  mounted to the distal end of the draw-out rod  42 , and an operating handle  45  for imparting twist to the draw-out rod  42 .  
      The drawing device is operated as follows. First, the electrodeposition portion  44  is fixed to a damaged part D. Then, the ratchet lever  43  is repeatedly operated to move the draw-out rod  42  away from the damaged part D. At this time, the electrodeposition portion  44  is fixed to the damaged part D, so that the damaged part D is drawn out to the main body  41  side together with the electrodeposition portion  44 . When the drawing-out of the damage part D is completed, the operating handle  45  provided on the draw-out rod  42  is twisted, whereby twist is imparted to the electrodeposition portion  44 , and the electrodeposition portion  44  is detached from the damaged part D. By thus repeatedly operating the ratchet lever  43 , the damaged part D is gradually drawn out toward the normal position. The draw-out rod  42  is graduated, and, owing to this graduation, it is possible to grasp the amount by which the draw-out rod  42  is drawn out.  
      Subsequently, the method of using the above-described sheet metal repair support device  1  will be described with reference to the operation of drawing out a damaged part formed on a panel surface of a vehicle.  
      First, prior to the installation of the sheet metal repair support device  1 , the configuration of the damaged part is grasped. Then, the sub frame  20   b  is caused to slide in the axial direction of the main frame  10  through the intermediation of the slide bracket  60 , and the leg parts  70  are caused to slide relative to the sub frames  20 , adapting the distance (span) between the leg parts  70  and their positions to the configuration of the damaged part. This operation corresponds to the operation of enlarging the distance between the leg parts  70  with respect to the damaged part, and is not such a sophisticated operation as would require, for example, correct computation of the exact positions of the leg parts  70 .  
      Further, in this embodiment, after adjusting the distance between the sub frames  20   a ,  20   b , a jig X as shown in  FIG. 1  is fitted into the end portion of each of the sub frames  20   a ,  20   b  in order to maintain this distance, and in this state, the present device  1  is fixed to the damaged part. That is, the movement of the sub frames  20   a ,  20   b  is regulated by the jig X, making it possible to fix the present device  1  to the damaged part.  
      As shown in  FIG. 1 , each jig X is equipped with a main body portion X 2  whose total length can be adjusted by an adjusting portion X 1 , and engagement portions X 3  provided on the both ends of the main body portion X 2 , which can be engaged with the end portions of the sub frames  20   a ,  20   b ; when using the jig, each of the engagement portions X 3  is engaged with the end portion of the corresponding sub frame  20 , and the total length is adjusted by the adjusting portion X 1 , whereby an external force (tension) is imparted to the sub frame  20 , restraining undesired movement of the sub frame  20 .  
      Subsequently, the leg part brackets  80  are operated to impart inclination to the support angles of the leg parts  70 . More specifically, as shown in  FIGS. 1 and 4 , the leg parts  70  are fixed to the panel surface at angles providing predetermined inclinations with respect to normal lines L extending from the panel surface to which the leg parts  70  are fixed.  
      While the inclination angles of the leg parts  70  can be set arbitrarily, inclination is preferably imparted to the leg parts  70  within a range in which the angles θ made by the damaged part to be drawn out and the leg parts  70  are acute angles, and more preferably, within the range of 60 to 80 degrees.  
      To be more specific about the angles θ made by the above-mentioned damaged part and the leg parts  70 , the angles θ correspond to the angles made by the leg parts  70  and the straight lines connecting the proximal points of the normal lines extending from the panel surface toward the leg part brackets  80  and the positions where the leg parts  70  supported by the leg part brackets  80  are fixed.  
      Subsequently, the fastening member  62  provided on the slide bracket  60  is released, and the main frame  10  is opened in a direction opposite to the damaged part, using the stationary bracket  50  as a fulcrum. Then, in this state, operations, such as masking and the marking of draw-out points, are effected on the damaged part.  
      Then, the main frame  10  is connected to the sub frame  20   b  again through the intermediation of the fastening member  62 . Next, the drawing device  40  is operated to lower the draw-out rod  42 , and the electrodeposition portion  44  provided at the distal end of the draw-out rod is welded to the damaged part. Then, the ratchet lever  43  provided on the drawing device  40  is operated to draw up the damaged part to a desired position (see  FIG. 6 ).  
      In this way, in the sheet panel repair support device  1  according to this embodiment, the leg parts  70  are fixed so as to provide predetermined inclinations with respect to the normal lines L extending from the panel surface, and in this state, the operation of drawing out the damaged part is conducted.  
      Thus, the reaction force in the direction perpendicular to the panel surface acting on the leg parts  70  when drawing out the damaged part is diffused to the outside of the damaged part, whereby a secondary damage of the panel surface due to the operation of drawing out the damaged part is avoided.  
      In this embodiment, the leg parts  70  are fixed to the panel surface by utilizing the suction force of the suction pads  72 . Thus, the dispersed reaction force (e.g., the reaction force horizontal to the panel surface) is absorbed by deformation of the suction pads. That is, by adopting the suction pads  72 , it is possible to further reduce the reaction force acting on the panel surface.  
      Further, the inclinations, i.e. the support angles, of the leg parts  70 , can be easily changed whenever necessary by operating the leg part brackets  80  provided on the sub frames  20 .  
      Further, in the sheet metal repair support device  1  according to this embodiment, it is possible to separate the sub frame  20   b  and the main frame  10  at the slide bracket  60 , so that, as stated above, even after the installation of the sheet metal repair support device  1 , it is possible to perform operation over the damaged part.  
      Further, in this embodiment, by sliding the main frame  10  relative to the sub frames  20 , and by sliding the drawing device  40  relative to the main frame  10 , it is possible to move the drawing device  40  in plane-matrix directions of the damaged part (the X-direction and the Y-direction in  FIG. 2 ). Thus, it is possible to perform the drawing-out operation in diverse drawing orders, for example, in a drawing order in which the damaged part is drawn out successively in a circle from the outer periphery toward the center of the damaged part.  
      Next, a jig used in sheet metal repair by means of the sheet metal repair support device  1  will be described.  
      While in the above example the leg parts  70  are directly fixed to the panel surface P, by using the jig described below, it is possible to install the sheet metal repair support device  1  in a stable manner over the damaged part in a condition in which the fixing positions for the leg parts  70  cannot be secured in the vicinity of the damaged part.  
      In the following, the jig for the sheet metal repair support device  1  of the present invention will be described with reference to the drawings.  
       FIG. 1  shows a jig  100  forming fixation places for the leg parts  70  on a side surface of a tire T by utilizing the tire T of the vehicle.  
      As shown in  FIG. 1 , the jig  100  is equipped with a semi-circular acrylic resin plate  101  whose radius is substantially equal to the radius of curvature of the tire T, and L-shaped stays  102  (base plate portions) provided in the peripheral edge of the acrylic resin plate  101 ; when using the jig, the stays  102  are engaged with the tread surface of the tire T to secure a fixation surface (fixation plate) formed by the acrylic resin plate  101  on the side surface of the tire T.  
      Then, by fixing the leg parts  70  to the side surface of the tire T, it is possible to fix the sheet metal repair support device  1  in a stable manner over the damaged part even in a position where the panel area is small, for example, in a position in the vicinity of the tire house.  
      Further,  FIGS. 7 through 9  show a jig  110  which secures fixation places for the leg parts  70  by utilizing the hood of a vehicle.  
      For example, as shown in  FIG. 7 , the jig  110  is equipped with a base plate portion  111  to be fixed to the portion of a hood B around the damaged part, and a fixation plate  112  forming, by using the base plate portion  111  as a fulcrum, a fixation surface serving as a panel surface constituting the proper fixation place in the vicinity of the leg parts  70  of the sheet metal repair support device  1 .  
      Further, as shown in  FIG. 7 , in using the jig, the jig  110  is fixed to the hood B of the vehicle, and the leg parts  70  of the sheet metal repair support device  1  are fixed to the fixation plate  112 . That is, by using the jig  110 , even in a condition in which the fixation surface for the leg parts  70  cannot be secured on the panel surface P in the vicinity of the damaged part, it is possible to secure the fixation surface for the leg parts  70  in the vicinity of the leg parts  70  by utilizing another panel surface (e.g., the hood).  
      In the following, its construction will be described in detail.  
      As shown in  FIG. 8 , the base plate portion  111  consists of a flat plate having on the back side a plurality of suction pads  113 , whereas the fixation plate  112  is fixed to the end portion of the base plate portion  111  through the intermediation of hinges  114 . Further, as shown in  FIG. 9 , between the base plate portion  111  and the fixation plate  112 , there is provided an angle adjusting mechanism. This angle adjusting mechanism is equipped with a stay  111   a  provided on the surface of the base plate portion  111 , a stay  112   a  extending from the fixation plate  112 , and a lock lever  115  securing the stays  111   a ,  112   a  at fixed positions.  
      When operating the jig, the fixation plate  112  is adjusted to a desired angle with respect to the base plate portion  111 , and then the lock lever  115  is operated to collectively fasten the stays  111   a ,  112   a . Thus, the support angle of the fixation plate  112  with respect to the base plate portion  111  is maintained at an appropriate angle.  
      Further, the suction pads  113  are provided so as to be slidable with respect to the base plate portion  111 , and position adjustment of the base plate portion  111  and the fixation plate  112  is possible even after the fixation of the suction pads  113 .  
      The construction of the sheet metal repair support device  1  and the construction of the jig described above, are only presented as a preferred example; regarding their details, they allow modifications as appropriate according to various specifications.  
      For example, while in the sheet metal repair support device  1  described above the leg parts  70  are swingably connected to the sub frames  20  through the intermediation of the leg part brackets  80 , it is also possible to impart inclination to the leg parts  70  by fixing the leg parts  70  to the sub frames  20  and changing the angle of the sub frames  20  with respect to the main frame  10  when installing the sheet metal repair support device  1 .  
      Further, the sub frames  20 , the main frame  10 , etc. are not always indispensable; for example, a construction may also be adopted in which the leg parts  70  are directly connected to the drawing device  40 .  
      Further, while in the above example the inclination setting for the leg parts  70  is effected by imparting inclination to the leg parts within a range in which the angles θ made by the damaged part and the leg parts  70  are acute angles (angles smaller than a right angle), it is not absolutely necessary to do so; to disperse the reaction force acting on the panel surface, the angles θ made by the damaged part and the leg parts  70  may also be obtuse angles exclusive of 90 degrees.  
      In the case in which the setting is made in acute angles, the leg parts  70  are widened out, so that, for example, in a configuration with a swollen central portion as in the case of a vehicle door panel, it is possible to diffuse the reaction force efficiently to the outside of the damaged part.