Abstract:
The crosshead for a universal testing machine includes a interior face which is formed at angle to the front face which is typically about 17°. A wedge pocket is machined with walls perpendicular to the interior face, and therefore at an angle other than perpendicular to the front surface of the crosshead. This allows a rectangular steel plate to be oriented to match the machine column locations. Therefore, the material cost is significantly reduced as no special casting shape is required.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a rectangular crosshead design for a universal testing machine wherein the specimen pocket is machined at an angle to the front surface of the crosshead rather than perpendicular to the front surface. 
   2. Description of the Prior Art 
   In the prior art, the universal testing machine for determining tensile strength and similar characteristics of a sample is well developed. The testing samples in universal testing machines are typically held by jaws which are mounted in wedge-shaped pockets formed in crossheads. These wedge-shaped pockets of the crosshead and the jaws contained therein are configured and arranged to exert a holding force on the specimen. These pockets are typically machined with sides that are perpendicular to the exterior front and rear walls of the crosshead. While this prior art crosshead design is intuitively simple and well-adapted to its present uses and purposes, this results in a very heavy and expensive crosshead. Additionally, crossheads of the prior art may include offset cast portions for the apertures for receiving the columns of the universal testing machine. This, in particular, requires a large special shape casting to obtain the correct shape to work with a universal test machine. Purchasing a casting requires high upfront fees in the form of pattern charges and storage of the pattern. Additionally, castings of this size are more expensive than a purchased steel plate stock in the typical volumes employed. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a crosshead for a universal testing machine which can be produced at reduced cost. 
   It is therefore a further object of the present invention to provide a crosshead for a universal testing machine which achieves the above object without requiring any substantial or costly modifications in the universal testing machine. 
   These and other objects are attained by providing a rectangular crosshead design with a wedge pocket machined at an angle instead of perpendicular to the front surface of the crosshead. This allows a rectangular steel plate to be oriented to match the column locations of the universal testing machine so that no little or no modifications to the universal testing machine are required. Due to the rectangular shape, the material cost is significantly reduced as no special casting shape is required. Steel plate stock can be used thereby eliminating the pattern and pattern storage fees. This can result in as much as a thirty percent or more savings in many applications. 

   
     DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein: 
       FIG. 1  is a front perspective view of a prior art crosshead with offset column locations. 
       FIG. 2  is a top plan view of a prior art crosshead with offset column locations. 
       FIG. 3  is a top plan view of the crosshead design of the present invention. 
       FIG. 4  is a front plan view of the crosshead design of the present invention, shown at a similar angle as illustrated in  FIG. 3 . 
       FIG. 5  is a rear perspective view of the crosshead design of the present invention. 
       FIG. 6  is a front perspective view of the crosshead design of the present invention. 
       FIG. 7  is a front perspective view, partially in phantom, of the crosshead design of the present invention. 
       FIG. 8  is a front perspective view of the crosshead design of the present invention, illustrating the jaws and associated mounting components. 
       FIG. 9  is a front plan view of the crosshead design of the present invention, illustrating the jaws and associated mounting components. 
       FIG. 10  is a perspective view of a universal testing machine configured to utilize the crosshead design of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that  FIGS. 1 and 2  illustrate a prior art crosshead  100  which is formed by casting. Prior art crosshead  100  includes a front wall  102  and a rear wall  104  bounding the central portion  106 . Wedge pocket  108  with inclined side walls  110 ,  112  and bottom wall  114  is formed within central portion  106 . Inclined side walls  110 ,  112  and bottom wall  114  are all formed to be perpendicular with front and rear walls  102 ,  104 . 
   The configuration of the inclined sidewalls  110 ,  112  within wedge pocket  108  allows jaws (not shown) to be inserted into wedge pocket  108  and a tensile (or similar) testing specimen (not shown) to be placed between the jaws or within a jaw assembly. Thereafter, during tensile or similar on the specimen, the jaws or jaw assembly are urged upwardly into a progressively narrowing gap between the inclined sidewalls  110 ,  112 , the jaws or jaw assembly are urged into a progressively tighter grip on the specimen. 
   First and second offset cast portions  120 ,  122  are formed in mutually offset positions on respective first and second sides  124 ,  126  of crosshead  100 . First and second offset cast portions  120 ,  122  include respective first and second column apertures  128 ,  130  for receiving the threaded columns of the universal testing machine. The interior of first and second column apertures  128 ,  130  typically include threaded nut assemblies. 
   Due to the intricate shape of the prior art crosshead  100 , special casting is required which, as described above, is relatively expensive. 
     FIGS. 3-9  illustrate various views of crosshead  10 , an embodiment of the present invention. Crosshead  10  is typically formed from rectangular torch cut plate stock rather than by casting. When viewed from above, as shown in  FIG. 3 , has a rectangular cross section with front face  12 , rear face  14 , left end face  16  and right end face  18 . First and second column apertures  20 ,  22  are formed inwardly adjacent from respective left and right faces  16 ,  18  and are configured and arranged to receive the threaded columns (see elements  504 ,  506  of  FIG. 10 ) of the universal testing machine (see element  500  of  FIG. 10 ). First and second column apertures  20 ,  22  include threaded nut assemblies  21 ,  23  through which the threaded columns of the universal test machine pass, and which are intended to operate substantially the same as those in the prior art. 
   Triangular wedge  24  is excised or otherwise formed so as to create interior face  26  which is typically oriented about 17° (rather than 0°) with respect to front face  12 , and therefore 73° (rather than 90°) with respect to the left and right faces  16 ,  18 . This angle may vary somewhat (depending upon the degree of relative offset of the cast portions  120 ,  122  in the prior art crosshead  100  of  FIGS. 1 and 2  which is to be replaced by the crosshead  10  of  FIGS. 3-9 ), but interior face  26  is envisioned typically to be something other than parallel or perpendicular with respect to front face  12  or with respect to an imaginary line drawn between the centers or axes of first and second column apertures  20 ,  22 . Wedge pocket  32  is formed with internal walls perpendicular to interior face  26 . More specifically, inclined internal side walls  34 ,  36  and bottom internal wall  38  are all formed to be perpendicular with face  26  and hence not perpendicular with front and rear faces  12 ,  14 . 
   As shown in  FIG. 7 , passageway  40  extends from bottom internal wall  38  through the base of crosshead  10  thereby encompassing piston  78  which rises to urge the jaws  52 ,  54  into a tightened position around the specimen (not shown). 
   As shown in  FIGS. 8 and 9 , typically jaw assembly  50  is formed from jaws  52 ,  54  with respective outer inclined walls (not shown) complementary to the inclined internal sidewalls  34 ,  36 . Left and right front support plates  73 ,  74  hold the jaw assembly  50  in place, with debris covers  75 ,  76  positioned thereover. 
   As shown in  FIGS. 4-9 , material is excised or otherwise removed (or not initially formed) from the upper portions inwardly adjacent from left and right faces  16 ,  18 , generally in the area of first and second column apertures  20 ,  22  to create areas of reduced height  42 ,  44 . 
   The resulting configuration allows the crosshead  10  to be formed from torch cut plate stock rather than the casting of the prior art, thereby resulting in substantially reduced weight and manufacturing costs. Additionally, the relative orientations of the first and second column apertures  20 ,  22  and the wedge pocket  32  are maintained so as to be substantially identical to the corresponding elements of the prior art crosshead  100  of  FIGS. 1 and 2 , thereby allowing the prior art crosshead  100  to be replaced by crosshead  10  without substantial modification to the universal testing machine  500  of  FIG. 10 . 
   Crosshead  10  is used in the universal testing machine  500  as shown in  FIG. 10 . The sample or specimen (not shown) is engaged by the jaws of the fixed cross portion  502  and by the jaws of crosshead  10 . The threaded columns  504 ,  506  pass through threaded nut assemblies  21 ,  23 , and tensile or similar testing is performed in a manner with the universal testing machine  500  functioning in a conventional manner. 
   Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.