Abstract:
A frame section for a switching cabinet rack having at least one inner wall which faces the inside area of the switching cabinet and is fitted with a row of regularly spaced fastening cavities. The fastening cavities do not reduce rigidity to any significant degree. At the same time fixtures can be mounted on the fastening cavities in a stable manner by designing the fastening cavities as slotted openings with clear openings larger in the longitudinal direction of the frame section than the width of the clear openings perpendicular to the longitudinal direction.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a frame section for a rack of a switchgear cabinet having at least one interior wall facing an interior of the switchgear cabinet, which has at least one row of fastening receivers cut at even distances. 
     2. Description of Prior Art 
     A rack of this type is described in German Patent Reference DE 33 44 598. The rack has twelve identical frame sections, which are connected with each other. The frame sections support two interior walls, which are connected with each other at right angles. A row of fastening receivers is cut into each of these interior walls. The fastening receivers are formed by holes with an essentially square cross section. 
     SUMMARY OF THE INVENTION 
     It is one object of this invention to provide a frame section of the type mentioned at the outset, wherein impairment of the stiffness because of the fastening receivers is small and wherein a stable installation of built-in units at the fastening receivers is possible. 
     In accordance with this invention this object is achieved with fastening receivers embodied as slit-shaped holes, having a clear opening width in a longitudinal direction of the frame section greater than a clear opening width transversely to the longitudinal direction. 
     The longitudinally oriented slit-shaped fastening receivers affect only slightly the stiffness, in particular the distortion resistance, of the frame section. Because the fastening receivers extend in the longitudinal direction of the frame section, a stable attachment of built-in units is possible. Fastening elements of a structural height, which is matched to the clear opening width in the longitudinal direction of the frame section, can be supported in the fastening receivers. Because a large opening width is provided, the fastening elements can also have a correspondingly massive dimension in the longitudinal direction of the frame section. The main load axis when attaching built-in units now extends along the frame section in such a way that the fastening element introduced into the fastening receiver can optimally absorb the occurring load. 
     Therefore the result is a frame section having a high degree of stiffness achieved by special dimensioning of the fastening receivers. The solid attachment of built-in units on the fastening receivers is also possible. 
     When dimensioning the fastening receivers, the clear opening width of the fastening receivers in the longitudinal direction of the frame section should be at least twice as large as the opening width transversely to the longitudinal direction. The most diverse fastening elements can be fixed in place in the fastening receivers. The employment of hook-shaped fastening elements is advantageous. Mounting rails can be used as built-in units, for example, and are bent from sheet metal. In this case the hook-shaped fastening element is punched out of the sheet metal. The clear opening width transversely to the longitudinal direction of the frame section is then matched to the thickness of the sheet metal. It is therefore possible to provide a simple and cost-effective connecting mechanism due to the slit-shaped fastening receivers. 
     In a preferred embodiment of this invention two interior walls, which extend at right angles to each other, face the interior of the switchgear cabinet, and a further profiled side embodied as an interior wall is connected at right angles with the interior walls. Each one of the interior walls/profiled sides has a row of fastening receivers. A plurality of fastening possibilities is provided by this frame section, which can be used depending on the space availability in an interior of the switchgear cabinet. In particular, one profiled side is always parallel in relation to an interior wall, resulting in two levels of fastening, which extend parallel with each other. The number of attachment possibilities for built-in units can also be easily increased because the interior wall facing the interior of the switchgear cabinet respectively has at least one further row of fastening receivers. The rows of fastening receivers extend parallel with respect to each other. It is conceivable in connection with a rack assembled from the frame legs in accordance with this invention, that the horizontal frame sections, which form a bottom frame and a cover frame, have two rows of fastening receivers on an interior wall extending vertically with respect to the side of the rack. At least the row of fastening receivers facing the side of the rack forms the slit-shaped holes, and the rows of fastening receivers transition into the rows of fastening receivers of the vertical frame sections. Because the rows of fastening receivers of the horizontal frame sections transition into the vertical frame sections, built-in units can be fastened in the corners. It is an advantage if the fastening receivers transition into each other in a grid layout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention will be explained in greater detail by referring to an exemplary embodiment represented in the drawings wherein: 
     FIG. 1 shows a rack for a switchgear cabinet, having frame sections, in a perspective lateral view; and 
     FIG. 2 shows a detailed representation of a corner area of the rack in accordance with FIG.  1 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A rack for a switchgear cabinet is shown in FIG.  1 . The rack is essentially assembled from a bottom frame  10 , a cover frame  20  and four vertical frame sections  40 . The vertical frame sections  40  connect the bottom frame  10  with the cover frame  20 . The bottom frame and cover frame  10  and  20  are identically constructed, so that they can be interchanged. 
     The bottom frame and cover frame  10  and  20  each have four horizontal frame sections  21 ,  22 , which are arranged at right angles with respect to each other. On interior walls facing the interior of the rack, the frame sections  21 ,  22  have rows of fastening receivers  23 ,  24 ,  24 . 1 . The vertical frame sections  40  also have fastening receivers  45 ,  46 , which are facing an interior of the rack. Threaded receivers  24 . 2 , or respectively  44 , are arranged between the individual fastening receivers  23 ,  24 ,  24 . 1 ,  45 ,  46 . 
     The vertical frame sections  40  are connected with the bottom, or respectively cover frame  10 ,  20  by connectors  30 . The connectors  30  are arranged in the area of corner receivers  25  of the bottom, or respectively cover frame  10 ,  20 . Screw connections or welds, for example, are for fastening the vertical frame sections  40  on the connector  30 . 
     A corner area of the rack in accordance with FIG. 1 is shown in greater detail in FIG.  2 . 
     FIG. 2 shows the two horizontal frame sections  21 ,  22  identically constructed. Facing the interior of the rack, the two interior walls  25 . 1 ,  25 . 2  are connected at right angles to each other. The horizontal, upward facing interior wall  25 . 1  makes a transition into a bevel  26 . The bevel  26  extends parallel with the side of the rack. Lateral walls or a cabinet door can be placed against bevel  26 , with a seal between them. The bevel  26  makes a transition into two exterior walls  27 , which are also placed at right angles to each other. Thus the exterior walls  27  are arranged parallel with respect to the interior walls  25 . 1 ,  25 . 2 . A bevel of the lateral wall, or respectively of the cabinet door, can be received in the area formed by the setoff of the two exterior walls  27 . The vertical exterior wall  27  is connected with the vertical interior wall  25 . 2  via the bottom  28 , so that a closed hollow profile results for the horizontal frame sections  21 ,  22 . 
     The vertical interior wall has a row of fastening receivers  23 . The fastening receivers  23  are embodied as holes of essentially rectangular cross section. Two rows of fastening receivers  24 ,  24 . 1  are provided on the upward facing horizontal interior wall. The two rows of fastening receivers extend parallel with each other in the longitudinal direction of the frame section  21 ,  22 . While the fastening receivers  24  located on the inside are identical to the fastening receivers  23  of the vertical interior wall  25 . 2 , the fastening receivers  24 . 1  are slit-shaped. The slit-shaped fastening receivers  24 . 1  have a clear opening width in the longitudinal direction of the frame sections  21 ,  22  which is greater than the opening width transversely to the longitudinal direction. Threaded receivers  24 . 2  are respectively arranged between the individual fastening receivers  23 ,  24 ,  24 . 1 . The threaded receivers  24 . 2  are stamped out in an untrimmed shape, into which tapping screws can be screwed. 
     The horizontal frame sections  21 ,  22  are connected at right angles to each other and form the corner receiver  25 , which is open toward the outside. The vertical frame section  40  is placed against the connector  30  in the corner receiver  25 . 
     The vertical frame section  40  has four interior walls  41 ,  42 . The interior walls  41  are at right angles to each other and form an interior receiver facing the interior of the rack. Vertically extending mounting rails can be fastened in the interior receiver. The two interior walls  42 , which are embodied as profiled sides, are connected at right angles to the two interior walls  41 . The interior walls  42  also extend at right angles with the sides of the rack. Each one of the interior walls  41 ,  42  has a row of fastening receivers  45 ,  46 . The fastening receivers  45 ,  46  are also embodied in a slit-shaped manner, the same as the fastening receivers  24 . 1  of the horizontal frame sections  21 ,  22 , wherein the main direction of extension runs in the longitudinal direction of the frame section  40 . On the exterior of the rack, the interior walls  42  terminate flush with the interior walls  25 . 1  of the horizontal frame sections  21 ,  22 . Since the fastening receivers  24 . 1  of the horizontal frame sections  21 ,  22  and the fastening receivers  45  of the vertical frame sections are spaced apart at a same distance from the sides of the rack, the fastening receivers  24 . 1 ,  45  transition into each other. Therefore a circumferential fastening frame results. The fastening receivers  24  can transition in the same way into the fastening receivers  46  of the interior wall  41 . 
     As shown in the drawings, a small structural size of the individual frame sections  21 ,  22 ,  40  can be realized by means of the narrow fastening receivers  24 . 1 ,  45 ,  46 . Also, the fastening receivers  24 . 1 ,  45 ,  46  hardly weaken the frame sections  21 ,  22 ,  40 , so that the frame sections  21 ,  22 ,  40  have great rigidity. At the same time it is possible to fasten built-in units solidly on the fastening receivers  24 . 1 ,  45 ,  46 . A large degree of flexibility is provided by the multitude of fastening possibilities for the attachment of built-in units in the interior of the switchgear cabinet. It is possible to form two vertical fastening levels, one behind the other, with the four interior walls  41 ,  42  of the vertical frame sections  40  in the direction of the one horizontal frame section  21 , as well as the other frame section  22 . Thus, the fastening levels are respectively formed by one interior wall  41  and a further interior wall  42 .