Abstract:
In a preferred embodiment, a vibrator table apparatus includes a primary table member driven by at least two vibrators, having upper and lower surfaces and defining x and y axes. The improvement of this embodiment includes at least one of the upper and lower surfaces of the primary table member defining an opening for each of a first plurality of substantially parallel channels and an opening for each of a second plurality of substantially parallel channels substantially perpendicular to the first plurality of channels.

Description:
FIELD OF THE INVENTION 
     This invention relates to vibrator testing tables and, more particularly, to a new table frame design. 
     BACKGROUND OF THE INVENTION 
     Few products are sold by their manufacturer without some type of testing being conducted. Such testing may be as simple as manually ascertaining whether certain parts are securely affixed—or as complex as “stress testing.” In stress testing (or “stress screening” as it is sometimes called), products exhibiting “infant mortality” fail outright during the test. Or as the result of such testing, a product may evidence the likelihood of early failure in the operating environment. 
     Stress testing is most frequently employed with respect to products used in demanding applications and for which exceptionally-high reliability is required. Examples include products used on ground-traveling military equipment and products (e.g., electronic and electromechanical products) used in aircraft of essentially all types. 
     Stress testing may be carried out in any of several different ways. One type of test regimen involves imposing rapid, extreme changes in temperature upon the product. As an example, a test chamber may be used to change the temperature of a product between −70 degree C. and 200 degree C. over a period of, say, 5 minutes. Another type of test regimen involves using a test chamber to repetitively and dramatically change the relative humidity of air around a product. And humidity-based testing may also be accompanied by temperature-based testing and vice versa. 
     Yet another type of stress testing involves testing a product by subjecting it to vibrations of the type which might be encountered in actual product use. For example, U.S. Pat. No. 2,438,756 (Larsen) explains that the apparatus described therein is used to vibration-test electrical apparatus for airplanes, ships and the like. The unit described in U.S. Pat. No. 3,748,896 (Barrows) is said to be used for testing parts of a motor vehicle. And vibration testing is often conducted in conjunction with testing using another regimen, e.g., temperature. 
     Vibration testing is carried out by mounting the product to be tested upon some sort of platform or table and then vibrating the table using a rotating eccentric or a linear vibrator. Examples of devices used to create vibratory motion are shown in the Barrows patent and in U.S. Pat. Nos. 4,106,586 (Stafford) and 5,154,567 (Baker et al.). 
     In general, tables used to stress test products by application of vibration to such products are of two broad types, namely, flexible and rigid. An example of the former is disclosed in U.S. Pat. No. 4,735,089 (Baker et al.) and has a flexure member, i.e., a honeycomb structure, between two plates. An example of the latter is disclosed in FIGS. 12-14 of U.S. Pat. No. 5,412,991 (Hobbs) and has a rigid core plate between upper and lower plates. 
     While the prior art vibrator tables have been generally satisfactory for their intended purposes, they are not without disadvantages. In multi-degree freedom of testing vibration typically occurs on 3 axes, x, y and z. In a rigid table design there is significantly more vibration energy in one axis (typically the z-axis). A further disadvantage is that minimal energy is imparted in the 0-1000 Hz bandwidth. This rigid design has led to flexible table designs having a grouping of segmented plates, a composite of layers of different materials or combination of the two. These tables have acted to increase the energy in the 0-1000 Hz bandwidth but still did not normalize the energy between the three axes. 
     A disadvantage to known flexible tables is that they are highly expensive to manufacture since they utilize complex layering that is difficult to produce. Furthermore, such tables wear out or fail more rapidly since the materials used, or the interface adhering the materials together, deteriorate over time. 
     Therefore, an improved vibrator-driven table frame overcoming some of the problems and shortcomings of the prior art would be a distinct advance. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide an improved vibrator table frame that overcomes some of the problems and shortcomings of the prior art, including those referred to above. 
     Another object of the invention is to provide an improved vibrator table flame that is of a flexible design that is easy and/or inexpensive to manufacture. 
     Another object of the invention is to provide an improved vibrator table frame that equalized energy levels across the X, Y and Z axes. 
     Another object of the invention is to provide an improved vibrator table frame that improves energy imparted to the object being tested between 0 and 1000 Hz. 
     How these and other objects are accomplished will become apparent from the following descriptions and the drawings. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment, a vibrator table apparatus includes a primary table member driven by at least two vibrators, having upper and lower surfaces and defining x and y axes. The improvement of this embodiment includes at least one of the upper and lower surfaces of the primary table member defining an opening for each of a first plurality of substantially parallel channels and an opening for each of a second plurality of substantially parallel channels substantially perpendicular to the first plurality of channels. 
     In a second embodiment, the first plurality of channels is substantially parallel with the x-axis. Alternatively, the first plurality of channels could be offset from parallel to the x-axis. In such an embodiment, it would be preferable that the offset from parallel to the x-axis by about 45 degrees. 
     In a third embodiment, the at least one of the upper and lower surfaces is the upper surface. The lower surface then defines an opening for each of a third plurality of substantially parallel channels and an opening for each of a fourth plurality of substantially parallel channels substantially perpendicular to the third plurality of channel, whereby the upper surface of the member includes a plurality of platforms. 
     In another embodiment, the first plurality of channels defined by the at least one of the upper and lower surfaces are spaced substantially equally from one another and the second plurality channels defined by the at least one of the upper and lower surfaces are spaced substantially equally from one another, thereby creating a grid of intersecting channels. 
     In a further embodiment, the channels of each of the first, second, third and fourth pluralities channels are spaced substantially equally apart from one another, thereby creating an upper and a lower grid of intersecting channels. 
     In yet other embodiments, the first plurality of channels and the third plurality of channels, and/or the second plurality of channels and fourth plurality of channels are offset from one another. 
     In still further embodiments at least one intersection of a first plurality channel with a second plurality channel, if not most of the intersections, defines an opening. 
     In another embodiment, a primary table member for use in a vibrator table apparatus includes an upper surface, a lower surface, two length sides and two width sides. The member also includes a first plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the top surface of the member; and a second plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the top surface of the member. 
     In a further embodiment, the table member includes a third plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the bottom surface of the member; and a fourth plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the bottom surface of the member. 
     In other embodiments, the first and third pluralities of channels extend between the two width sides. Alternatively, each of the channels in the first and third pluralities of channels could extend between a length side and a width side. 
     In yet other embodiments, the first and second pluralities of channels are substantially perpendicular to each other, and/or the third and fourth pluralities of channels are substantially perpendicular to each other. 
     In a still further embodiment, a method is disclosed wherein the method includes providing a testing apparatus, the apparatus including a primary table member and a plurality of vibrators attached to the primary table member. The member having an upper surface, a lower surface, two length sides, two width sides. The member further including a first plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the top surface of the member and a second plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the on the top surface of the member. The method next including securing a product to be tested to the primary table member and energizing the vibrators. 
     In another embodiment, the method also includes utilizing a table member that includes a third plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the bottom surface of the member and a fourth plurality of channels defined substantially parallel to each other in the member, extending between two of the sides and open on the bottom surface of the member. 
     The benefit of the present invention is two-fold: first, it allows for more vibration energy to be transferred to the object to be tested below 1000 Hz and second, it allows the energy to be more consistent between the x, y and z axes. This is shown in  FIGS. 10 and 11 .  FIG. 10  shows energy transferred in a typical prior art table frame design. As can be seen on the x and y axes little energy is transferred below 1000 Hz. Furthermore, the energy in the z-axis is much greater than in the x-axis or y-axis. 
     Comparatively, in  FIG. 11  the energy transfer of a table made according to the present invention is shown. This chart shows improved energy transfer below 1000 Hz and much more consistent energies across the x, y and z axes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective top view of a preferred embodiment of a table frame in accordance with this invention. 
         FIG. 2  is a top plan view of the table frame of  FIG. 1 . 
         FIG. 3  is a side plan view of the table frame of  FIG. 1 . 
         FIG. 4  is a perspective bottom view of the table frame of  FIG. 1 . 
         FIG. 5  is a bottom plan view of the table frame of  FIG. 1 . 
         FIG. 6  is a perspective top view of an alternative embodiment of a table frame. 
         FIG. 7  is a perspective bottom view of the table frame of  FIG. 6 . 
         FIG. 8  is side plan view of the table from of  FIG. 1  with vibrators attached and including an object to be tested secured to the table frame via standoffs. 
         FIG. 9  is side plan view of the table from of  FIG. 1  with vibrators attached and including an object to be tested secured directly to the table frame. 
         FIG. 10  is a chart showing the vibration energy along the x, y and z axes of a typical prior art vibrator table frame. 
         FIG. 11  is a chart showing the vibration energy along the x, y and z axes of a vibrator table frame made according to the current invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to  FIGS. 1-5 , a highly preferred embodiment of the present inventive vibrator table frame or member  10  is shown. The table frame  10  includes an upper surface  12  and a lower surface  14  and has length sides  16  and width sides  18 . The table frame  10  defines an x-axis  20  and a perpendicular y-axis  22 . Although in these preferred embodiments the table frame  10  is shown to be square, the shape of the table frame could be any shape known to those in the art, such as circular, rectangular, or irregular (not shown). In a circular or irregular shape the x-axis and y-axis could be defined as needed to accomplish testing. 
     The table frame  10  defines a plurality of channels  24  on both surfaces. A first plurality  26  of channels  24  is defined parallel to each other in the table frame  10  and extending between the width sides  18 . Each of the first plurality  26  of channels  24  is open on the upper surface  12  and on the width sides  18 . In this preferred embodiment the first plurality  26  of channels  24  is also parallel to the x-axis  20 . A second plurality  28  of channels  24  is defined parallel to each other in the table frame  10  and extending between the length sides  16 . Each of the second plurality  28  of channels  24  is open on the upper surface  12  and on the length sides  16 . In this preferred embodiment the second plurality  28  of channels  24  is also parallel to the y-axis  22 . 
     As seen best in  FIG. 5 , the lower surface  14  also includes two distinct pluralities of channels  24 . A third plurality  30  of channels  24  is defined parallel to each other in the table frame  10  and extending between the width sides  18 . Each of the third plurality  30  of channels  24  is open on the lower surface  14  and on the width sides  18 . In this preferred embodiment the third plurality  30  of channels  24  is also parallel to the x-axis  20 . A fourth plurality  32  of channels  24  is defined parallel to each other in the table frame  10  and extending between the length sides  16 . Each of the fourth plurality  32  of channels  24  is open on the lower surface  14  and on the length sides  16 . In this preferred embodiment the fourth plurality  32  of channels  24  is also parallel to the y-axis  22 . 
     It is highly preferred that within each of the pluralities of channels  24 , the channels  24  are spaced equally apart from each other. As seen best in  FIGS. 2 and 5 , this spacing creates a grid-like arrangement of intersecting channels  24  on both the upper surface  12  and the lower surface  14 . Referring now to  FIG. 3 , it is also highly preferred that the parallel pluralities of channels  24 , for example the second plurality  28  and fourth plurality  32  (both extending between the length sides  16  and parallel with the y-axis  22 ), be arranged as offset from one another, thereby reducing the material of the table frame  10  as much as possible while still providing the needed strength. However, in other, less-preferred embodiments (not shown) the channels  24  could be less offset, or even aligned with each other if each channel  24  was not as deep, or if the table frame  10  was thicker. 
     The upper surface  12  of the table frame  10  further includes a plurality of platforms  34 . The platforms  34  are defined by the grid of intersecting channels  24  and thus are spaced equally apart from each other. In preferred embodiments the platforms  34  include attachment holes  36 . As discussed further below, the attachment holes  36  can either be used to mount an object to be tested, or to attached standoffs. 
     The intersections of the channels  24  of the first plurality  26  with the channels  24  of the second plurality  28  further can define openings  38 . In highly preferred embodiments, most, if not all, of these intersections define openings  38  and the openings  38  are circular. The purpose of the openings is two-fold. First, to minimize the amount of material in the frame  10  to maximize the flexibility, and second, to give mounting points for vibrators  40 . The table frame  10  itself can be made of a variety of materials known to those in the art such as a polymer or magnesium; however, it is preferred that the table frame  10  is made from aluminum. 
     An alternative embodiment of the present invention is shown in  FIGS. 6 and 7 . In this embodiment each of the channels  24  extend between a length side  16  and a width side  18 . The channels  24  of the first plurality  26  and third plurality  30  are offset from parallel with the x-axis by about 45 degrees. Since, the second plurality  28  and fourth plurality  32  are substantially perpendicular to the first plurality  26  and third plurality  30 , respectively, the second plurality  28  and fourth plurality  32  are offset from the y-axis by about 45 degrees. 
     Referring now to  FIGS. 8 and 9 , in use the table frame  10  is a part of a vibrator testing apparatus (not shown) known in the art. Vibrators  40  are attached to this preferred embodiment of the table frame  10  at the openings  38 . An object  42  to be tested is then secured to the table frame  10 . This can be done in a variety of manners. For example,  FIG. 8  shows the object  42  secured to the table frame  10  on top of a plurality of standoffs  44 , the standoffs  44  being attached to the table frame  10  at the attachment holes  36 . Alternatively, as shown in  FIG. 9 , the object  42  can be placed directly onto the table frame  10 . Once the object  42  is attached, the vibrators  40  are then energized and the table frame  10  and object  42  are vibrated. 
     While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting.