Abstract:
A device comprising two hollow profiles which are arranged approximately at a right angle from each other and each of which is provided with a profiling channel that extends parallel to the longitudinal axis (A) of the profile and an undercut longitudinal groove in at least one lateral face of the profile, the longitudinal groove extending parallel to the profiling channel. The two hollow profiles are held together by a connecting screw whose shaft engages into the profiling channel of one hollow profile and whose screw head is mounted within an undercut longitudinal groove of the other hollow profile. The periphery of the screw head is provided with grooves or notches that run on planes extending from the longitudinal axis (M) of the shaft while forming ribs therebetween.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a device comprising two hollow profiles arranged in a butt-jointed manner approximately at right angles to one another, each of which has a profile channel parallel to its profile longitudinal axis and also, in at least one profile side surface, an undercut longitudinal groove parallel to the profile channel. The invention furthermore relates to a tool for operating the connecting bolt. 
   Document DE 201 06 561 discloses a device for connecting a first profile bar to a second profile bar which bears with a front face against a longitudinal side of the first profile bar. These profile bars are provided with undercut longitudinal grooves along their longitudinal sides and contain a clamping screw with a screw head and a threaded shaft which can be fixed in the region of the screw head in the undercut longitudinal groove of the first profile bar and can be screwed with its threaded shaft into a longitudinal bore formed in the second profile bar. Said screw head has, on a disc-shaped collar, a toothing which can be brought into active connection with a turning tool. The turning tool is a bar with a toothing integrally formed in an axis-parallel manner at one of its ends, which toothing can be brought into contact with the toothing on the collar. 
   Another device is described in EP 0 136 431 A2. Two hollow profiles of square cross section with a central profile channel and a longitudinal groove running centrally in each profile side surface are connected by means of a commercially available screw. The latter passes through an elongate insertion plate which is arranged in the undercut groove space of the longitudinal groove, said plate having legs which protrude in a U-shaped manner and which pass through the longitudinal groove for holding purposes and to prevent twisting. In order to be able to operate the screw, there must be in the bottom of the groove a number of openings which penetrate the hollow profile; the screwdriver which is to be inserted into a slot in the screw head is introduced through one of these openings. 
   The hollow profiles, which are usually extruded from an aluminium alloy, must therefore be reworked in a special way after they have been manufactured; the making of the radial openings is very complicated and considerably reduces the stability of the profile. 
   Knowing this prior art, the inventor set himself the aim of improving the system outlined above and avoiding additional processing of the holding profiles that are used. The longitudinal grooves are to remain open so that it is possible where necessary to introduce flat elements. 
   SUMMARY OF THE INVENTION 
   This aim is achieved by a device comprising two hollow profiles arranged approximately at right angles to one another, each of which has a profile channel parallel to its profile longitudinal axis (A) and also, in at least one profile side surface, an undercut longitudinal groove parallel to the profile channel, wherein the two hollow profiles are held together by a connecting screw, the shaft of which engages in the profile channel of one hollow profile and the screw head of which is mounted in an undercut longitudinal groove of the other hollow profile, wherein the screw head is provided on its periphery with grooves or notches which run in planes extending from the shaft longitudinal axis (M) and form ribs between them. 
   According to the invention, the screw head of the connecting screw tapers provided on its periphery—which is circular in cross section—with grooves or notches which run in planes extending from the shaft longitudinal axis—and defined by the latter in terms of their course—and form ribs between them. It has proven to be advantageous that the screw head tapers conically towards a head surface remote from the shaft, and this wall surface which is inclined at an angle with respect to the shaft longitudinal axis contains said grooves or notches. This angle should preferably be approximately 45°. 
   According to a further feature of the invention, the screw head should have, between a shaft-facing connection surface and the inclined wall surface, an annular section of constant diameter in which the shaft-facing ends of the grooves or notches form a crenellated edge pattern. The inclined wall surface should end at the head surface of the screw head or—in another embodiment—at a radial step surface, which latter surrounds in an annular manner an integrally formed top body. This tooth-free or notch-free end section is supported on the groove bottom when screwed on, and ensures a mating hold. 
   The shaft of the connecting screw (also referred to as a connecting bolt) which adjoins this screw head is advantageously provided with a cutting thread which cuts a counter-thread in the inner surface of the profile channel during assembly. 
   According to the invention, assigned to the shaft of the connecting screw is a slip-on collar which is provided with a central opening and can be placed against the connection surface of the screw head, the width of said slip-on collar being shorter than the width of the longitudinal groove of the hollow profile; the slip-on collar can thus be lowered into the latter. Preferably, a collar piece should be integrally formed on a base strip of the slip-on collar, wherein the length of said base strip is greater than the width of the longitudinal groove of the hollow profile; as a result, when the slip-on collar is rotated, the latter strikes the inside of the longitudinal groove on both sides in a retaining manner. 
   This embodiment is supplemented in that a threaded sleeve with outer thread is axially assigned to the collar piece of the slip-on collar, said threaded sleeve receiving the free end of the shaft. In this case, the length of the shaft should correspond approximately to the height of the slip-on collar plus the length of the threaded sleeve. However, an axially oriented widening of the opening should be integrally formed in the lower surface of the base strip in order to temporarily—and securely—receive a region of the annular section of the screw head. Said threaded sleeve is advantageously designed such that its outer diameter corresponds approximately to the width of the slip-on collar, so that the threaded sleeve can thus be inserted in the longitudinal groove. 
   The scope of the invention also includes a tool for operating the connecting screw in a screw head arranged in a groove space of a hollow profile. This tool comprises a round profile with an insertion head provided at one end, said insertion head having longitudinal notches which are made in its (preferably conically tapering) peripheral surface and receive the radially protruding ribs of the screw head so as to operate or rotate the connecting bolt; the pattern of the longitudinal notches on the tool thus corresponds to the arrangement of the ribs on the screw head. 
   It has proven advantageous to make the diameter of the round profile shorter than the depth of the groove space of the hollow profile, in order to make it possible to insert the tool into the groove space. 
   Moreover, the angle between the axis of the round profile and the peripheral or outer surface of the insertion head should be approximately 20° to 40°, in particular approximately 25°. This likewise facilitates insertion of the tool, the grooves of which are to receive the ribs of the screw head on the connecting screw. 
   In order to prevent damage to the hollow profile, according to the invention a protective section of a protective surface bears against the described peripheral or outer surface of the insertion head, said protective surface being releasably fixed to the round profile, namely on the selected groove bottom. This protective surface should be designed as a protective plate and have a holding section which is radial with respect to the axis of the round profile and surrounds the latter and also a lateral section which is bent out from the surface of said holding section, on which lateral section said protective section is integrally formed in an inclined manner. 
   By virtue of the embodiment according to the invention, there is no longer any need for special configuration or reworking of the hollow profile. The connecting screw is simply rotated into the core hole—coarse-pitch thread or self-cutting thread—of one hollow profile and then pushed into the end of the other hollow profile. It is also conceivable firstly to screw the aforementioned threaded sleeve into the core hole, so as to provide for example a steel coarse-pitch thread for screwing in the connecting screw or toothed screw. To reduce friction, the latter can be provided with a coating of lubricant to make it easier to screw in. 
   Moreover, to prevent it from being screwed out, the screw head can be provided on the underside with raised areas in the form of dotted lines or teeth. 
   The screw head with the toothed edge should be as large as possible so as to achieve the greatest tightening torque. At the same time, however, it should not protrude in a disruptive manner beyond the core region of the profile. The greater the difference between the number of teeth of the screw and the number of teeth of the screwdriver, the greater the translation and thus the peripheral force which act on the toothed screw or connecting screw during tightening. 
   In addition, a drive may be provided in the screw head, which drive corresponds either to that of the toothed edge screwdriver in order to be able to operate with just one key or another profile (e.g. hexagon socket, six-lobe drives) by means of which the screw is firstly to be screwed into the core hole and then screwed back out somewhat, before it is introduced together with the hollow profile into the slot of the mating profile and tightened. 
   The dimensions for the screw and the screwdriver of course depend on the profiles to be connected. However, all compatible profiles can be connected by means of the same screw. The stability of the connection is sufficient for simple frames, protective fences, housings, etc. Securing against twisting of the profiles to be connected is provided if at least one groove is occupied by a flat element. The connection is extremely simple, fast and thus of course very cost-effective. 
   The tool is inserted close to said connecting bolt into the longitudinal groove which receives it, and its inclined insertion head is pushed in between the groove bottom and the screw head. When the ribs of said screw head mesh with the grooves of the tool, operation of the connecting bolt can readily be carried out. The inventor&#39;s aim is thus achieved in a particularly simple manner. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages, features and details of the invention will emerge from the following description of preferred examples of embodiments and with reference to the drawing, in which: 
       FIG. 1  shows the front view of an extruded hollow profile comprising longitudinal grooves; 
       FIG. 2  shows an enlarged longitudinal section through parts of two hollow profiles arranged at right angles with respect to one another, with a connecting member; 
       FIG. 3  shows a detail from  FIG. 2 ; 
       FIG. 4  shows a partially cut-away side view of a connecting member configured differently from  FIGS. 2 ,  3 , in an axially offset position of its individual parts; 
       FIG. 5  shows a side view of the connecting member rotated through 90° compared to  FIG. 4 ; 
       FIG. 6  shows a top view of the connecting screw of  FIG. 3 ; and 
       FIG. 7  shows a top view of the connecting screw of  FIGS. 4 and 5 . 
   

   DETAILED DESCRIPTION 
   A hollow profile  10  of square cross section extruded from a light metal alloy, having cross-sectional axes B, B 1  as axes of symmetry placed through the centre Z of its front face  18 —said centre Z being defined by a profile channel  14  of circular cross section of diameter d which runs in its central profile body  12  in the profile longitudinal axis A and is provided with radial edge grooves  16 —has in each case in the centre of its profile side surfaces  20  a longitudinal groove  22  having a width b of for example 8 mm, said longitudinal groove being delimited at both ends by shaped ribs  24  with a thickness a of in this case 4 mm and merging into an undercut groove space  26  towards the profile longitudinal axis A. Said groove space is a channel-like recess of approximately triangular cross section which is overlapped by said shaped ribs  24  and has a depth e determined from the groove bottom  27  of 10 mm and a maximum width f of 22 mm and provides an axial insertion track  28  of height h on the inner side of the shaped ribs  24 . 
   As shown in  FIGS. 2 ,  3 , and  6 , assigned to the front face  18  of the hollow profile  10  is a hollow profile  10   a  of the same shape which crosses over its profile longitudinal axis A. In order to be able to fix the two hollow profiles  10 ,  10   a  to one another, use is made of a specially designed connecting screw  30 . This is made of a hard metal—compared to the hollow profile  10 ,  10   a —and comprises a screw shaft  32  having a length i of for example 25 mm and a disc-shaped screw head  36  having a diameter g of in this case 15 mm and a height n of 5 mm. Said screw shaft  32  is provided with a cutting thread  34  (shown only schematically in  FIGS. 2 ,  3  for the sake of clarity), the outer diameter d 1  of which is greater than the diameter d of said profile channel  14 . The cutting thread  34  has cut into the inner surface of said profile channel in the illustrated connecting position, and the shaft longitudinal axis M runs in the profile longitudinal axis A. 
   The shaft-facing stop surface  38 ,  38   a  of the screw head  36 , which crosses over the shaft longitudinal axis M, merges into a cylindrical annular section  40 ,  40   a  having a height n 1  and said diameter g of the peripheral wall of the screw head  36 . Adjoining the annular section  40 ,  40   a  is a wall surface  42 ,  42   a  of axial height n 2  which in cross section is inclined at an angle w of in this case 45° with respect to the shaft longitudinal axis M; integrally formed in this wall surface  42 ,  42   a  in the radial direction are grooves or notches  43 ,  43   a  which between them form ribs  44 ,  44   a  and a crenellated edge pattern  45  in said annular section  40 ,  40   a . At a distance from said stop surface  38 ,  38   a , the conically tapering wall section  42 ,  42   a  and thus also each of the notches  43 ,  43   a  merge into an annular, radially oriented step surface  46  which surrounds an integrally formed top body  48  having a height n 3 . The smooth peripheral surface thereof is inclined towards the axis in cross section in a manner corresponding to the associated wall section  42 ,  42   a  within the screw head  36 . The top body  48  ends at a head surface  50  which adjoins the screw head  36 , wherein a hexagonal socket  49  can be seen in said head surface. 
   In order to produce the desired connection of the two hollow profiles  10 ,  10   a , the screw head  36  of the connecting bolt or connecting screw  30  is pushed into one of the groove spaces  26  of the lower hollow profile  10   a  in  FIGS. 2 ,  3 ; in the process, the screw shaft  32  slides in the longitudinal groove  22  of the hollow profile  10   a  in an axis-parallel direction. At a predefined point, the front face  18  of the other hollow profile  10  is brought towards the profile longitudinal axis A of the first hollow profile  10   a  at right angles, and the profile channel  14  of said second hollow profile  10  is axially assigned to the screw shaft  32 . 
   Rotation of the screw shaft  32  into the profile channel  14  or the profile body  12  of the other hollow profile  10  which surrounds the latter is carried out by means of a tool  52  which is partially shown schematically in  FIG. 2 . This tool consists of a round profile  54  having a diameter q of in this case 8 mm, preferably a steel rod, said round profile optionally being bent at an angle in the longitudinal direction. Said diameter q should be shorter than the height or depth e of the groove space  26  of the hollow profile  10 ,  10   a . This round profile  54  is designed to a length t of approximately 10 mm at one end as an insertion head  56  with a peripheral surface  57  which tapers conically at an angle y of approximately 25°, said peripheral surface being provided with parallel longitudinal notches  58  for receiving ribs  44 ,  44   a  of the screw head  36 . A correspondingly inclined protective section  66  of a protective plate which is essentially designed as an angled piece bears against the peripheral or outer surface of said insertion head  56 ; said protective plate is placed onto the round profile  54  by means of a radial section  62 , with a lateral section  64  of the protective plate  60  running parallel to the longitudinal axis Q of said round profile at a distance therefrom. This lateral section is angled towards the insertion head  56  close to the latter at a bend point  65 , forming said protective section  66 . 
   As shown in  FIG. 3 , the insertion head  56  of this tool  52  is pushed in between the screw head  36  of the installed connecting screw  30  and the groove bottom  27  (covered by the protective plate  60 ) of the corresponding longitudinal groove  22 , with which the insertion head axis Q delimits an angle w 1 . By rotating the insertion head  56  about its longitudinal axis Q, with the insertion head rolling on the protective section  66  of the protective plate  60 , the toothed screw head  36  of the connecting screw  30  is operated and thus the screw shaft  32  is screwed in. 
   A different embodiment of the connecting bolt  30   a  is shown in  FIGS. 4 ,  5  and  7 . The screw head  36   a  thereof has a relatively high annular section  40   a  which is adjoined by a conical wall section  42   a  of approximately the same height n 2 . The latter ends at a free head surface  50   a ; the above-described top body is omitted here. 
   Assigned to the connecting bolt  30   a  is a slip-on collar  70  of rectangular outline having a height i 1  and a width g 1  on a base strip  71 —having a height i 2 , a length c and a width b 1 —and an integrally formed collar piece  72  having a height i 3 . The rectangular slip-on collar  70  is provided with a central opening  74  of diameter d 2  for receiving the shaft  32  of diameter d 1 , which opening opens at the lower surface  73  into a circular widening  76  for receiving the annular section  40  of the screw head  36   a . Said widening has a small axial depth i 4  and a diameter g 1  which slightly exceeds the diameter g of the screw head  36   a . 
   Shown above the slip-on collar  70  in  FIGS. 4 ,  5  is an axially assigned M8 threaded sleeve  80  having a length k and an outer diameter g 2  which corresponds approximately to the diameter g of the screw head  36   a . The wall  82  of this threaded sleeve  80  is provided with an outer thread  84 . Once the slip-on collar  70  has been fitted, the shaft  32  is introduced into the interior  78  of the threaded sleeve  80 , in which it is then securely seated. This unit consisting of connecting bolt  30   a , slip-on collar  70  and threaded sleeve  80  is then supplied to a hollow profile  10   a . Since the width b of the longitudinal grooves  22  of the latter is somewhat greater than the width b 1  of the slip-on collar  70 , the latter can be passed radially through one of the longitudinal grooves  22  in an axis-parallel manner and be rotated in the associated groove space  26 ; the width f of said groove space is somewhat greater than the length c of the base strip  71 . In a hollow profile according to  FIG. 1 , the height i 2  of said base strip corresponds to the height h of the insertion track  28  of said groove space, or to the radial height of said groove space in the case of groove spaces of rectangular cross section. 
   The described embodiment according to  FIGS. 4 ,  5  has the advantage that it does not have to be pushed in from the front face  18  of the profile; following the described rotation of the slip-on collar  70 , the fixing operation for the other hollow profile  10  as shown in  FIGS. 1 to 3  can begin immediately. 
   Overall, therefore, the connecting screw or toothed screw  30 ,  30   a  can be screwed into the core hole or profile channel  14  of the hollow profile  10  to be butt-jointed in such a way that, thereafter, the screw shaft or toothed bolt  32  together with the screw head  36 ,  36   a  can be inserted into the longitudinal groove  22  at the point to be connected. The movable screw head  36 ,  36   a  is rotated in the fixing position transversely to the longitudinal groove  22  and then the toothed bolt  32  is tightened by means of the tool  52 .