Abstract:
An improved device for simulating gravel impact damage on panels, such as protected and unprotected areas of painted vehicle panels, is disclosed. The gravel impact damage simulator includes an enclosure, a gravel inlet port having an extension spout, a motor-driven rotatable impeller below the inlet port, a downwardly angled baffle between the inlet port and the impeller, and a test panel slot through which a test panel may be inserted into the enclosure. During operation, gravel is introduced through the extension spout and inlet port. The gravel drops into the angled baffle, where it is directed toward the rotating impeller. The rotating impeller strikes the gravel and projects it toward the test panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/838,470 filed Jun. 24, 2013, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to gravel impact damage simulators, and more particularly relates to portable simulators that can demonstrate gravel impact damage on protected and unprotected areas of painted test panels. 
     BACKGROUND INFORMATION 
     Vehicles such as cars and trucks are susceptible to damage from gravel and other road debris. Various protective measures have been taken to reduce paint chipping and other vehicle damage, including the application of protective urethane sheets or films over the areas of vehicles that are most likely to be damaged. The effectiveness of such protective sheets and films may be demonstrated by projecting gravel against protected and unprotected areas of a painted panel, and comparing the resulting damage in the protected and unprotected areas. 
     Standard tests have been developed to measure paint chipping resistance. For example, the ASTM Standard Test Method for Chipping Resistance of Coatings, ASTM D3170-12, is a test procedure where standardized road gravel is projected within an enclosed cabinet or module by means of a controlled air blast onto a test specimen. In accordance with the ASTM D3170-12 test, air that has been pressurized to 70 psi is released through a valve and is used to project the gravel toward the test specimen. The test specimen may then be analyzed to determine the amount of chipping of the painted surface. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved device for simulating gravel impact damage on panels, such as protected and unprotected areas of painted vehicle panels. 
     An aspect of the present invention is to provide a gravel impact damage simulator comprising: an enclosure; a gravel inlet port extending through a wall of the enclosure, wherein the gravel inlet port comprises an extension spout extending from the wall of the enclosure; a motor-driven rotatable impeller below the inlet port within the enclosure, wherein the rotatable impeller has an axis of rotation that is offset at an angle measured from a vertical direction; a downwardly angled baffle positioned in a gravel flow path between the gravel inlet port and the rotatable impeller; and a test panel slot through a wall of the enclosure structured and arranged to receive a test panel to be positioned in the gravel flow path. 
     Another aspect of the present invention is to provide test panels for use in such a gravel impact damage simulator 
     A further aspect of the present invention is to provide a method of using such a gravel impact damage simulator. 
     These and other aspects of the present invention will be more apparent from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a gravel impact damage simulator in accordance with an embodiment of the present invention with its side panel removed to show the internal components of the simulator. 
         FIGS. 2 and 3  are side views of the gravel impact damage simulator of  FIG. 1 . 
         FIG. 4  is a side view of the gravel impact damage simulator of  FIG. 1 , with its side removed to reveal the internal components thereof. 
         FIGS. 5 and 6  are top views of the gravel impact damage simulator of  FIG. 1 . In  FIG. 6 , the top of the simulator has been removed to show the internal components thereof. 
         FIG. 7  is an isometric view of a painted test panel having one side covered with a protective film and another side exposed, illustrating the lack of damage on the protected side but significant damage on the exposed side after being subjected to a gravel impact test in a gravel impact damage simulator of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-6  illustrate various features of a gravel impact damage simulator  10  in accordance with an embodiment of the present invention. The simulator  10  includes an enclosure  12  having a base  13 , a top  14 , side walls  15  and  16 , and end walls  17  and  18 . As shown most clearly in  FIGS. 1, 4 and 5 , a slot  20  is provided in the top  14  for receiving a test panel  40 , as more fully described below. A top window  21  is provided in the top  14  of the enclosure  12 . An extension spout  22  having a central opening is mounted above an inlet port through the top  14  of the enclosure  12 . The extension spout  22  has an upper cylindrical section, a lower cylindrical section of smaller diameter than the upper section, and a conical section connecting the upper and lower cylindrical sections. The height of the extension spout  22  is typically at least as large as the diameter of the inlet opening through the top  14 . 
     As shown most clearly in  FIGS. 1, 4 and 5 , an angled baffle  24  is secured to the top  14  of the enclosure  12  and includes a downwardly angled ramp surface that directs the flow of gravel and prevents unwanted backward ejection of the gravel during operation of the gravel impact damage simulator  10 , as more fully described below. The angled baffle  24  has a sloped surface with a slope angle typically ranging from 10 to 60 degrees, for example, from 15 to 45 degrees, or from 20 to 40 degrees. A handled cup  26  is shown in  FIG. 1  covering the opening of the extension spout  22 . The cup  26  may be removed from the extension spout  22  and used to measure and pour a selected amount of gravel (not shown) into the extension spout  22  of the simulator  10  during a gravel impact damage simulation. The handled cup  26  may be re-positioned over the opening of the extension spout  22  to act as a lid during the simulation. A safety release panel  28  is slidably mounted in a housing  29  below the extension spout  22 . Gravel that is loaded into the extension spout  22  may be held in the spout until the safety release panel  28  is pulled away from the housing  29 , thereby allowing the gravel to drop into the enclosure  12 . The safety release panel  28  may optionally be spring loaded to bias the safety release panel  28  toward its closed position within the housing  29 . 
     As shown in  FIGS. 1, 4 and 6 , a rotatable impeller  30  is provided inside the enclosure  12 . The rotatable impeller  30  includes multiple paddles  32  extending upwardly therefrom. Although four paddles  32  are shown in the figures, it is to be understood that the rotatable impeller  30  may have any other suitable number of paddles. Furthermore, although each paddle  32  shown in the figures has a generally rectangular shape, any other suitable shape may be used. As shown in  FIGS. 1 and 6 , the impeller  30  may rotate in the direction R. Although a counterclockwise rotation R direction is shown, it is to be understood that clockwise rotation may alternatively be used. 
     The angled baffle  24  is used to direct the gravel toward the underlying rotatable impeller  30 . While the angled baffle  24  shown in the figures comprises a planar sloped surface, it may alternatively have one or more side walls to help direct the gravel to a desired location in relation to the underlying impeller  30 . For example, the angled baffle  24  may have a side wall that directs the gravel toward the side of the impeller  30  that has the paddles  32  rotating toward the end wall  17   
     The rotatable impeller  30  is driven by an electric motor  34  connected to a power source by an electric power cord  35 . The electric motor  34  may be of any known type and can be operated at any desired speed. For example, the electric motor  34  may be operated at 1,600 rpm. The electric motor  34  may have a constant or variable rotational speed. A protective shield  33  extends from an upper part of the housing of the motor  34  in order to prevent possible damage from the impact of gravel during operation of the simulator  10 . As shown in  FIG. 4 , the rotational axis of the impeller  30  is oriented at an offset angle A from the vertical direction. In certain embodiments, the offset angle A may typically range from 1 to 45 degrees, for example, from 5 to 30 degrees, or from 10 to 20 degrees. 
     As shown most clearly in  FIGS. 1, 4 and 6 , a collection chute  36  is provided within the enclosure  12 . The collection chute  36  has four inwardly sloping sidewalls for directing gravel into a collection container  38  positioned below the collection chute  36 . An angled collar plate  37  surrounds the upper portion of the housing of the motor  34  below the rotatable impeller  30 . The angled collar plate  37 , in combination with the collection chute  36 , prevent gravel from contacting the base of the motor  34  and direct the gravel into the collection container  38 . An access door  39  permits access to the collection container  38  in order to recover gravel from the simulator  10  after operation thereof. Although the access door  39  is located in the side wall  15  of the simulator  10  in the embodiment shown in the figures, it is to be understood that the access door may be provided at any other suitable location, e.g., in the end wall  17  or the opposite side wall  16 . Removal of the collection container  38  from the enclosure  12  may be facilitated by a spring-loaded ejection mechanism (not shown) or the like. 
     The components of the portable gravel impact simulator  10  may be made of any suitable materials. For example, the enclosure  12 , extension spout  22 , angled baffle  24 , collection chute  36  and angled collar plate  37  may be made of metal or plastic, while the impeller  30  and paddles  32  may be made of plastic or metal. The interior surfaces of the enclosure  12  and/or the extension spout  22 , angled baffle  24 , collection chute  36  and angled collar plate  37  may optionally be lined with a cushioning or sound absorbing material in order to reduce the noise generated by the simulator during operation. 
     As shown in  FIG. 4 , a test panel  40  may be inserted through the slot  20  in a vertical direction adjacent to the end wall  17 , e.g., parallel therewith. The test panel  40  is thus positioned in the flight path of the gravel that is projected toward the panel  40 , by the rotatable impeller  30 . Gravel fed through the inlet opening  22  is projected by the rotating paddle wheel  30  in a generally horizontal direction against the test panel  40 . After the gravel impacts the test panel  40 , it drops through the collection chute  36  into the collection container  38 . Thus, during operation of the simulator  10 , a gravel flow path is provided though the extension spout  22 , past the safety release panel  28  when it is opened, and onto the angled baffle  24 , which directs the gravel toward the rotating impeller  30 . The rotating paddles  32  of the impeller  30  strike the gravel to project the gravel along the flow path toward the test panel  40 , where the gravel drops into the collection container  38 . The size and amount of gravel used in the simulator  10  may be selected as desired. For example, in a typical test run, one-half cup of pea-sized gravel may be poured through the extension spout  22 , and the test run may take from 1 to 5 seconds, e.g., 3 seconds. 
       FIG. 7  illustrates features of a test panel  40  in accordance with an embodiment of the present invention. The test panel  40  comprises a rectangular sheet of material such as metal or plastic that may be coated with paint. The test panel  40  has an unprotected side  42  in which the painted surface is exposed, as well as a protected side  44  that may be covered by a protective film  46 . For example, the test panel  40  may be a metal panel 3.5 inches wide and 10 inches long that has been painted with a color such as black or the like. The protective film  46  on the protected side  44  of the panel may include clear paint protection films, such as those sold by 3M and other manufacturers. 
     The test panel  40  illustrated in  FIG. 7  has been subjected to a gravel impact test in the simulator  10 , and a portion of the protective film  46  has been removed from the protected side  44  of the panel to reveal an undamaged painted surface  48  on the protected side  44  of the painted panel. As shown in  FIG. 7 , the protected side  44  of the panel  40  has not been damaged by the projected gravel, while the unprotected side  42  has suffered significant damage to the paint surface. 
     In accordance with embodiments of the invention, the portable gravel impact damage simulator  10  includes safety features that prevent unwanted projection of the gravel from the simulator during operation. Such features include the funnel-shaped extension spout  22  at the top of the enclosure  12  through which the gravel may be introduced, the safety release panel  28 , the angled baffle  24  positioned below the inlet opening and extension spout  22 , and the angled orientation A of the rotatable impeller  30 . The extension spout  22  provides a restricted opening through the top  14  of the enclosure  12 . The safety release panel  28  holds the gravel within the extension spout  22  until an operator opens the panel  28 . This allows time for the operator to place the handled cup  26  over the opening of the extension spout  22  to thereby provide a lid. After the safety release panel  28  is opened, it may be automatically retracted into its closed position, e.g., by a spring biasing mechanism. The size and orientation of the angled baffle  24  further reduces or eliminates the possibility of gravel traveling upward through the inlet opening  22  when the impeller  30  is rotating. Furthermore, the offset angle A of the impeller  30  causes most of the gravel to travel downward and away from the inlet opening  22  when the impeller  30  is rotating. Any gravel that is projected backward or upward during rotation of the impeller  30  is confined within the interior of the enclosure  12  by means of the angled baffle  24 , as well as the safety release panel  28  and/or placement of the cup  26  over the opening of the extension spout  22 . An additional safety procedure is to first load the gravel into the extension spout  22  with the safety release panel  28  closed, place the cup  26  over the opening of the extension spout  22 , turn the motor  32  on, and open the safety release panel  28  to allow the gravel to drop onto the rotating impeller  30 . The motor  34  is also protected against damage from gravel impact by the angled collar plate  37  and the protective shield  33 . During operation of the simulator, it is recommended that those in the vicinity should wear eye protection such as safety glasses or goggles. 
     Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.