Abstract:
A support structure includes a support bar and at least one section bar which is mounted to the support bar and includes two inner chambers which define a common transverse axis coincidental with the longitudinal axis of the support bar and which receive fixing screws for allowing attachment of the section bar to the support bar.

Description:
BACKGROUND OF THE INVENTION 
     The present invention refers to a support structure and to a method of connecting one structural element to another structural element. In particular, the present invention is concerned with a support structure of the type including a section bar mounted to a support bar via a screw connection. 
     It is known to provide a support structure by mounting an end face of the section bar to a longitudinal side of the support bar by means of screws, with the support bar having longitudinal sides provided with central longitudinal grooves, and with the screws being secured transversely in the support bar. The screw is threaded in an inner chamber of the section bar, with the inner chamber extending in longitudinal direction, and with the head of the screw bearing upon the support bar. 
     In such a conventional support structure, the screw is retained within the support bar by supporting the head of the screw with a washer or supporting disk or sliding block which is arranged in the undercut longitudinal groove facing the section bar. The screw is threadably engaged in an inner chamber, which is arranged concentrically to the mid-axis of the section bar by means of a suitable tool such as a screw driver which is inserted in a respective transverse bore in the support bar. 
     Because of the required precise central attachment, such a support structure or type of connection has only a relative small load carrying ability, and in particular is not sufficiently able to compensate torsional loads which means that the section bar is not secured against rotation when being mounted to the support bar. A further drawback is the necessity to insert the screw together with the supporting disk from the open end of the support bar which makes it difficult to accurately position the section bar and the support bar relative to each other. Also, a subsequent installation of a section bar between neighboring sections bars becomes very difficult because it requires complete dismantling of at least one section bar in order to allow the screw and the supporting disk to be inserted from the open end of the support bar for mounting the new section bar thereto. 
     A support structure of this type is thus difficult to make and complicated to handle so that its application becomes uneconomic. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved support structure obviating the afore-stated drawbacks. 
     In particular, it is an object of the present invention top provide an improved support structure in which the connection of a section bar to the support bar is easy and economical and yet the capability to withstand loads is greatly improved. 
     These objects and others which will become apparent hereinafter are attained by providing the section bar with two parallel and spaced inner chambers which define a transverse axis extending coincidental with the longitudinal axis of the support bar and by threadably engaging a screw into each inner chamber of the section bar, with at least one screw being secured in the support bar. 
     A support structure of this type allows a considerably facilitated attachment of the section bar to the support bar because the bore for allowing insertion of the screws can be drilled in the support bar in situ i.e. when connecting the section bar to the support bar, and the screws can then be guided through the already positioned support bar and affixed to the section bar. 
     In accordance with the teaching of the present invention, the section bar is secured against rotation by inserting two screws into the section bar, with at least one screw being utilized for attaching the section bar to the support bar by securing the head of the screw in the inner chamber against a shoulder of the bore. 
     According to one embodiment of the present invention, in which one section bar is to be connected to the support bar, both screws may be used for attachment, with their head arranged in the respective inner chambers of the support bar. In accordance with another embodiment in which two section bars are to be connected in a same cross sectional plane of the support bar at neighboring longitudinal sides thereof, each section bar may be connected by one screw which is secured in the support bar and has a screw head received in an inner chamber of the section bar while the screw head of the other screw may be received in a respective longitudinal groove of the support bar. Suitably, the diameter of the screw head of the other screw approximately equals the width of the longitudinal groove. 
     In comparison to conventional support structures, the support structure in accordance with the present invention has a much improved static load carrying ability. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features and advantages of the present invention will now be described in more detail with reference to the accompanying drawing in which: 
     FIG. 1 is a fragmentary cross sectional view of one embodiment of a support structure according to the present invention, with a structural element serving as support bar and another like structural element being mounted thereto; 
     FIG. 2 is a fragmentary, partially sectional longitudinal view of the support structure of FIG. 1; 
     FIG. 3 is a fragmentary cross sectional view of another embodiment of a support structure according to the present invention, with a structural element serving as support bar and two other like structural elements being mounted thereto; and 
     FIG. 4 is a fragmentary, partially sectional longitudinal view of the support structure of FIG. 3. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Throughout all the FIGURES, the same or corresponding elements are always indicated by the same reference numerals. 
     Referring now to the drawing and in particular to FIGS. 1 and 2, there are shown a cross sectional view and a longitudinal view of one embodiment of a support structure according to the present invention, with a structural element serving as support bar 1 and another like structural element serving as section bar . The section bar 2 is mounted with one end face thereof to a longitudinal side of the support bar 1 by means of suitable fixing screws 4. It will be appreciated by persons skilled in the art that for sake of simplicity, the following description differentiates between support bar and section bar even though these elements are essentially identical. In the nonlimiting example of the drawing, the support bar 1 and the section bar 2 are of square cross-sectional area. 
     Each structural element, i.e. support bar 1 and section bar 2, includes an outer wall 9 which is provided with a central undercut longitudinal groove 3 along each longitudinal side thereof, and a central piece 10 extending inwardly from the outer wall 9. The central piece 10 is provided with four cirumferentially and uniformly spaced inner chambers 5 which extend parallel to the longitudinal grooves 3. 
     The inner chambers 5 of the support bar 1 and the section bar 2 are so arranged that upon connection of a section bar 2 to the support bar 1, two inner chambers 5 of the section bar 2 extend coincidental with the longitudinal axis of the support bar 1. In this manner, the inner chambers 5 are precisely positioned in central alignment with the pertaining longitudinal groove 3 of the support bar 1. 
     As is further shown in FIGS. 1 and 2, the support bar 1 includes bores 7 which are arranged in prolongation of the longitudinal axis of each inner chamber 5 of the section bar 2 for allowing insertion of the fixing screws and are drilled in the support bar 1 in situ i.e. when attaching a section bar 2 to the support bar 1. The bores 7 are of shouldered or step-shaped configuration and include an entrance opening which is distant to the section bar 2 and has a diameter exceeding the opposing exit opening which is slightly greater than the shank diameter of the fixing screw 4 and is located in the area facing the section bar 2. Thus, when being inserted for mounting the section bar 2 to the support bar 1, the fixing screws 4 are guided through the entrance opening of the bores 7 and through the center piece 10, with the shank threadably engaged in the inner chambers 5 of the section bar 2, and with the head 6 bearing upon a receiving surface within the respective inner chamber 5 against the shoulder of the bore 7. 
     By using suitable tools, such as drilling jigs or the like, the bores 7 can be precisely drilled when the section bar 2 is accurately positioned relative to the support bar 1. 
     As shown in particular in FIG. 2, the section bar 2 is mounted to the support bar 1 by two fixing screws 4 which extend off-center. In this manner, the section bar 2 is secured against rotation and the overall support structure has a considerably improved load carrying capability, in particular with regard to torsional loads. 
     Turning now to FIGS. 3 and 4, there are shown a cross sectional view and a longitudinal view of another embodiment of a support structure according to the present invention, with two section bars 2 mounted to two neighboring longitudinal sides of the support bar 1 so that the section bars 2 extend perpendicular to each other in a common cross sectional plane of the support bar 1. In order to prevent the section bars 2 from a rotation relative to the support bar 1, each section bar 2 is connected to the support bar 1 by one fixing screw 4 in a same manner as described with reference to the embodiment of FIGS. 1 and 2 and by another screw 8 which is threadably engaged in such a manner that its shank portion extends in the respective inner chamber 5 of the section bar 2 while its cylindrical head portion 6 bears upon the end face of the section bar 2, and thus is received in the pertaining longitudinal groove 3 of the support bar 1. In this embodiment, only one bore 7 in prolongation of the inner chambers 5 of each section bar 2 is of stepped configuration while the other bore 7 is continuous to allow the respective fixing screw 4 to pass therethrough and to rest with its head 6 in the corresponding longitudinal groove 3. Suitably, the screw head 6 of the fixing screw 8 has a diameter which approximately equals the width of the longitudinal groove 3 (see FIG. 3). 
     As shown in FIG. 4, the section bars 2 are mounted to the support bar 1 in such manner that the screw 8 of one section bar 2 is in alignment with the screw 4 of the other section bar 2 so that the screw 4 can be easily inserted in order to connect the section bar 2 with the support bar 1. 
     While the invention has been illustrated and described as embodied in a support structure, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims: