DE20218988U1 - Connecting device for connecting of two workpieces has shank of screw penetrating sleeve fitted in longitudinal slot in one workpiece so that threaded portion of screw protrudes beyond end face of workpiece - Google Patents

Abstract

The connecting device (34) for the connecting of two workpieces by a clamping screw or suchlike has the shank of the screw penetrating a sleeve (36) fitted in a longitudinal slot (20) in one workpiece so that a threaded portion of the screw protrudes beyond the end face (14) of the workpiece and is provided with a screw head (60) standing away from the end face. The screw head is designed to slide into an undercut longitudinal slot in the other workpiece.

Description

HlEBSCH BEHRMANN*'

PATENT ATTORNEYS
EUROPEAN PATENT AND TRADEMARK ATTORNEYS

Application for registration of a UTILITY MODEL Our reference: H284DE8 H/mü

(31) Priority number/

Priority Application Number:

202 14 703. 7

(32) Priority Date:

23.09.2002

(33) Priority Country:

(54) Title:

Connecting device for two workpieces, especially for strand-like hollow profiles

(71) Applicant:

Winfried K. W. Holscher Oberzellerhau 27 78224 Singen

(74) Representative:

Dipl.-Ing. Gerhard F. Hieb sch Dipl.-Ing. Dr.oec. Niels Behrmann -Patent Attorneys-Heinrich-Weber-Platz 1 D-78224 Singen

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Connecting device for two workpieces, especially for strand-like hollow profiles

The invention relates to a connecting device for connecting a first workpiece having an interior space -- in particular a strand-like hollow profile -- to another workpiece by means of a screw or similar element, the shaft of which passes through an opening in the workpiece and can be inserted into a counter element in the interior space.

The applicant's document DE 92 15 843 describes a connecting device for securing in an undercut interior of a longitudinal groove of a hollow profile or similar workpiece with at least one extension exceeding the width of the narrow groove cross-section for connecting a first workpiece having the longitudinal grooves to another workpiece, which in turn is provided with longitudinal grooves whose cross-section opens towards the profile face. This element is used in particular for metallic hollow profiles whose interior is not accessible from the outside; it is roughly cuboid-shaped and has at least two opposing flank walls inclined at an angle, as well as a spring element which on the one hand rests on one of the inclined flank walls and on the other hand engages over the narrower surface of the element with its free end. This is arranged at a distance from the element when the spring is in the relaxed state. If the spring element is pressed against the nut element, this can be easily pushed into the undercut groove - with its narrow side first.

In another connecting element for fixing in an undercut groove space of a longitudinal groove of a hollow profile according to DE 198 40 057 A1 of the applicant and for connecting the hollow profile to another, which in turn is provided with

A workpiece provided with the corresponding longitudinal grooves is ... .... ·· ·· ·· ·· ·· ·· ·· : &igr; .!

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Surface of angle arms of an angle-shaped shaped piece as a fastening or connecting device, at least one formation approximately corresponding to the width of a longitudinal groove forming the narrow groove cross-section is provided and at least one screw passing through the angle arm is attached; the width of the angle arm exceeds the width of the longitudinal groove. In addition, the cross-section of the formation tapers away from the surface of the angle arm.

Knowing these facts, the inventor set himself the goal of creating a reliable fastening option for extruded hollow profiles with a polygonal - preferably rectangular - cross-section, which can be connected to one another at approximately a right angle. Above all, a system is to be improved in which the profile face of one workpiece rests on a long side of the other workpiece and is held there - as far as possible against rotation.

The teaching of the independent claims leads to the solution of this problem; the subclaims indicate advantageous further developments. In addition, all combinations of at least two of the features disclosed in the description, the drawing and/or the claims fall within the scope of the invention.

According to the invention, the shaft of the clamping screw passes through a sleeve of the connecting device, which is fixed in a longitudinal groove of one workpiece in such a way that a threaded area of the clamping screw projects beyond the end face of the workpiece and is provided with a screw head at a distance from this; this is designed to be insertable into an undercut longitudinal groove of the other workpiece.

According to a further feature of the invention, the sleeve is arranged in the longitudinal groove of the workpiece in a detachable manner, whereby it has proven advantageous to connect the sleeve to the workpiece by means of a

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Tongue and groove system. The latter preferably contains lateral outer ribs of the sleeve, which can be inserted into radial grooves of the workpiece as counter-elements. These outer ribs, which are roughly triangular in cross-section, should merge with their rib surfaces into the grooves of the outer surface of the sleeve. In addition, the rib tips of several outer ribs - seen in cross-section - should run parallel to one another and thus create a comb-like profile, the teeth of which work together with the groove-like counter-elements to hold them together.

According to the invention, at least three groups of outer ribs are provided which are parallel to the longitudinal axis of the sleeve and which engage in radial grooves in the fastening position; the latter are formed centrally in the deepest part of the groove and in -- flanking -- surfaces of shaped ribs which face each other; the latter delimit the longitudinal groove which runs parallel to the axis in the outer surface of the profile and thereby overlap its undercut groove space.

It has proven to be advantageous if, when the sleeve is in the fastening position, one edge of the sleeve is approximately flush with the front face of the workpiece it is holding. A ring made of elastic material should also be arranged between the sleeve edge and the screw head, surrounding the threaded area of the clamping screw, thanks to which a better clamping position is achieved and damage to the thread is avoided.

In addition, the screw head of the clamping screw -- which has a blind hole with a polygonal cross-section on the front side -- should sit on the second sleeve edge in the clamping position so that the threaded area protrudes as far as possible from the sleeve into the undercut longitudinal groove of the other hollow profile.

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According to another feature of the invention, the screw head that can be screwed onto the clamping screw is plate-shaped and its length is somewhat shorter than the width of the groove space that accommodates it in the undercut longitudinal groove of the second hollow profile that is to be connected at right angles. It has proven advantageous to design the above-mentioned shaped ribs -- which border the longitudinal groove on both sides -- in the form of hooks and to design the surfaces of the hook ends that are directed towards the deepest part of the groove as abutments for the screw head. The height of the hook ends preferably corresponds to the height of the ring made of elastic material that is mounted between them.

In another embodiment of the connecting device according to the invention, a -- the inner surfaces of its four side walls touching -- is inserted into the interior of the workpiece or hollow profile of rectangular cross-section.
block-like connecting device and fixed in the hollow profile in such a way that one of its end faces is approximately flush with one end face of the hollow profile and a threaded area of the clamping screw projects beyond this end face into the interior of the other hollow profile and is connected there to a counter-element designed as a screw web and resting against the inner surface of this other hollow profile.

It has proven advantageous to equip the connecting device with a cross-sectionally cross-shaped shaped piece and to provide the lateral edges of its four shaped piece ribs each with a screw hole for a screw or screw sleeve penetrating the side wall of the hollow profile.

According to a further feature of the invention, the lateral front edge of the molded part rib contains at least one groove-like incision running transversely to the longitudinal axis of the molded part, the two side walls of which are preferably inclined at an angle to one another such that the transverse

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The section of the incision is widened outwards in order to accommodate a deformation of the side wall of the hollow profile when the shaped piece is in the clamping position; preferably two incisions opposite each other on either side of the longitudinal axis should accommodate one of the incisions - for example, created by a notch impact.

Advantageously, a passage for a retaining bolt forming the clamping screw runs along the longitudinal axis of the fitting; the screw holes of the fitting ribs then open into this passage, because the screws guided therein are intended to fix the retaining bolt.

The retaining bolt, which contains a threaded bolt as a clamping screw and is axially formed onto a bolt body, is designed in the region of that bolt body with at least one laterally formed recess as a locking element for a screw sleeve or screw provided in the screw hole of the shaped piece ribs.

In a further design, the bolt body is to offer a circumferential constriction delimited by two bolt sections tapering in opposite directions -- also as a locking element -- for a screw sleeve or screw provided in the screw hole of the shaped piece ribs.

According to the invention, the strip-like screw web of this design is also assigned a central formation on its lower surface, in the area of which a central screw opening is also provided for the thread area of the clamping screw. On this formation there is a round slot for better fixing of the screw web, the surface of which can be curved in a part-circular shape in cross section and/or provided with two counter-rotating desk surfaces in longitudinal section.

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The invention also includes a connecting device of the type described above, in which the two workpieces or hollow profiles with a rectangular cross-section are mitred and placed at right angles to one another with their slanted edges; in the corner area of the common interior space, at least two parallel insertion angles -- filling the cross-section of the interior space -- are firmly connected to one another and to the hollow profiles by means of screws or similar elements. Preferably, two insertion angles of approximately the same thickness are used, the angle legs of which are each provided with a receiving hole for screws. Advantageously, one insertion angle should be provided with screw holes passing through its angle legs as receiving holes and the other insertion angle should be provided with correspondingly arranged blind holes.

During assembly, the screw holes of one insertion angle should run coaxially to the blind holes of the other insertion angle as well as to openings in one of the profile side walls and together accommodate the screw or screw sleeve.

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Further advantages, features and details of the invention emerge from the following description of preferred embodiments and from the drawing, which shows in:

Fig. 1: the front view of an extruded hollow profile -- having longitudinal grooves -- with a connecting element inserted into one of the longitudinal grooves for a second hollow profile of the same shape attached at right angles to that hollow profile;

Fig. 2: the -- partially sectioned -- second hollow profile of Fig. 1 without connecting element;

Fig. 3: a part of the connecting element in an enlarged and partially sectioned side view compared to Fig. 1;

Fig. 4: an enlarged detail of Fig. 3;

Fig. 5: the front view of Fig. 3;

Fig. 6, 7: Side view and top view of a nut-like part of the connecting member;

Fig. 8: the partially sectioned front view of a hollow profile with a square cross section and a second hollow profile of the same shape, cut in the longitudinal direction and fixed to it at right angles by a connecting element;

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Fig. 9, 10: Side view and -- cross-shaped

Top view of part of the connecting member;

Fig.11, 12: two views of another

bolt-like part of the connecting member;

Fig. 13: a view of another embodiment of the part according to Fig. 11, 12;

Fig. 14,15: Bottom view and side view of a nut-like part of the connecting element enlarged compared to Fig. 8 to 13;

Fig. 16: the front view to Fig. 14, 15;

Fig. 17: Partial view according to arrow XVII of Fig. 14 after machining of this part;

Fig. 18: a partially sectioned side view of a frame corner made of two hollow profiles, each with a square cross-section, held together by connecting elements;

Fig. 19: a partially sectioned front view of Fig. 18;

Fig. 20: a side view of one of the two connecting elements to Fig. 18, 19;

Fig. 21: the front view of Fig. 20.

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An extruded hollow profile 10 with a square cross-section and an outer side length a of 40 mm in this case, with cross-sectional axes B, Bi as axes of symmetry in Fig. 1 through the center of its end face 14, determined by a profile channel 12 running in the longitudinal axis A of the profile, has in the middle of its profile side surfaces 16 a longitudinal groove 20 with a width b of, for example, 8 mm, delimited on both sides by cross-sectionally hook-like shaped ribs 18 with a thickness c of 2 mm in this case, which merges into a cross-sectionally undercut groove space 22 towards the longitudinal axis A of the profile. The hook ends 19 of the shaped ribs 18 are directed towards the bottom or groove depth 24 of the groove space 22. The latter is a groove-like recess overlapped by those shaped ribs 18, and the clear distance e of its bottom 24 from the shaped ribs 18 measures 10 mm, the maximum width f of the groove space 22 is approximately 20 mm.

The four surfaces forming the deepest grooves 24 are each assigned an arm-like rib 26 on both sides of their cross-section, which runs at an angle of 45° to the cross-sectional axes B, Bi. These ribs 26 merge into the corner regions 28 of the hollow profile 10; in each of these corner regions 28 there is - parallel to the longitudinal profile axis A - a corner channel 30 of almost square cross-section.

A second hollow profile 10 of identical cross-section is placed at a right angle to a side surface 16 of the upper hollow profile 10 in Fig. 1 - i.e. with its front surface 14 - and is connected by a connecting element 34. This has a sleeve 36 with a length h of 25 mm and an outer diameter d of 10.2 mm and an inner diameter di of 6.0 mm; the cylindrical sleeve space 37 merges at the upper sleeve end into a hexagonal area 38 with an axial length hi of 6 mm. Radial

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Outer ribs 40 from a projection width I ₁ of approximately 1 mm and a front width bi of 5 mm.

According to Fig. 4, the axially parallel section of the outer ribs 40 is triangular; the two rib surfaces 42 extending from the rib tip 41 determine a cross-sectional angle w of almost 45°. These rib surfaces 42 each merge into a groove 46 formed in the outer surface 39 with a depth i ₂ of 0.3 mm. The two side edges 41 of each of the outer ribs 40 -- arranged in three axially parallel groups with the same circumferential distance ζ -- are inclined to one another at an angle W ₁ of 15° according to Fig. 5. Furthermore, the length of the circumferential distance ζ corresponds approximately to that of the front width bi of the outer ribs 40.

A clamping screw 50 is mounted in the sleeve space 37, 38, the screw head 52 of which offers a hexagon hole 53 for an Allen key - not shown -, the screw head 52 resting against the lower sleeve edge 47 _t in the clamping position. The screw head 52 is connected to a round shaft 54 which merges into a screw shaft 55 as a threaded area. The free end of this shaft passes through a ring 48 made of elastic material in Fig. 1 which, in the clamping position, extends between the opposite hook ends 19 of the shaped ribs 18 of the hollow profile 10 and rests against the lower surface 58 of a nut-like screw head 60; the latter sits on the end surfaces of the two hook ends 19. The screw head 60, which is strip-like in plan view - with a thickness C ₁ of approximately 6 mm and a diagonal length &eegr; of 25 mm -- is, according to Fig. 6, 7, of diamond-shaped outline and equipped with a central screw hole 62 for the clamping screw 50. From the screw hole 62, the surface of the screw head 60 slopes down to its base edges 59.

To connect both hollow profiles 10, the sleeve 36 of the connecting member 34 is screwed into a groove space 22 of the lower hollow profile 10 in Fig. 1, with its outer ribs 40 being pushed into the groove depth during the turning process of the sleeve 36.

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ste 24 and the side surfaces of the hook ends 19 and produce radial grooves 32 as shown in Fig. 2. However, it is also possible to produce these radial grooves 32 in a different way. Here, the hollow profile 10 is then inserted parallel to the axis until the outer ribs 40 of the sleeve 36 engage in the correspondingly shaped radial grooves 32, which -- as indicated above -- are provided in the deepest part 24 of the groove and the side surfaces of the hook ends 19 facing each other. In this position of the sleeve 36, the upper sleeve edge 47 is aligned with the end face 14 of the hollow profile 10 and the longitudinal axis Ai of the sleeve 36 is parallel to the longitudinal profile axis A.

If the sleeve 36 is fixed in this way and the screw head 54 is inserted into one of the groove spaces 24 of the other or upper hollow profile 10, the clamping screw 50 can be turned in the sleeve 36 and the screw head 60 can be pressed with its lower surface 58 onto the hook ends 19; this press fit is a secure holder for the unit made up of the two hollow profiles 10 which are at right angles to one another.

The two hollow profiles 11 in Fig. 8, which are connected to one another at right angles, have a square cross-section with an outer side length a of, for example, 40 mm and are extruded from an aluminum alloy. The connecting element 70 here contains a steel molding 72 with a height h ₂ of 38 mm and a cross-shaped outline, the outline length Z ₁ of which measures 34 mm here and which can thus be inserted into the hollow profiles 11 with a corresponding clear width ai; the width fi of the metal ribs forming the steel molding 72

74 is 12 mm. The longitudinal axis Ai of the steel fitting 72 coincides with the longitudinal axis A of the hollow profile 11. Each of these metal ribs 74 is provided at its lateral front edges

75 -- at an average distance h3 of 9 mm -- to the lower longitudinal edge 76 with a notch 78 of 3 mm depth t, which widens conically outwards at an angle &khgr; of about 35° thanks to inclined side walls 77. At an average distance h ₄ of about 20 mm to

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that lower longitudinal edge 76, there is a screw hole 80 on each front edge 75 of the metal ribs 74 for a screw sleeve 82 -- which penetrates a side wall 17 of the hollow profile 11 to an opening 15 -- the latter fixes the steel molding 72 in the hollow profile 11 in such a way that its front surface 14 is aligned with the upper longitudinal edges 76 _a of the ribs 72. In addition, in order to intimately connect the steel molding 72 to the hollow profile 11, a recess 79 is then knocked into each of two opposite side walls 17, which nestles against the inner surfaces of the adjacent incisions 78. The depth and length of these incisions or notches 79 are determined by the shape of those incisions 78.

Fig. 10 shows a central passage 84 with a diameter d ₂ of 12 mm for a retaining bolt 86 with a total length η x of 45 mm that can be moved therein; a bolt body 87 with a length n ₂ of 33 mm of the retaining bolt 86, which fits into the passage 84, merges into an M8 threaded bolt 90. In the bolt body 87, at a distance n ₃ of 18 mm from its base surface 88, the center Q of an oval-shaped recess 89 can be seen (Fig. 11, 12). The longitudinal section shape of this is also determined by a right angle w ₂ that runs parallel to the bolt axis E.

In the design of the retaining bolt 86 _a according to Fig. 13, a constriction Qi can be seen in the bolt body 87 _a - at a distance n ₃ of 18 mm from the base surface 88 - from which conically widening bolt sections 89 _a extend.

Both recesses 89, Qi serve to accommodate the inner end of the mentioned screw sleeve 82 for fixing the position of the retaining bolt 86 or 86 _a .

In the clamping position, the threaded bolt 90 passes through an opening 15 _a in a side wall 17 of the upper hollow profile 11 in Fig. 8, so that a screw web 92 to be arranged in the profile interior 13 can be screwed onto it as a through-nut.

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with a length ei of 30 mm and a width b ₂ of 15 mm.

The lower surface 58 _a of the screw web 92 with a total height q of about 7 mm is provided in the longitudinal center with a step-like formation 94 with a width b ₃ of 11 mm; in its side surface 95, which is inclined at an angle w ₃ of 40° to the vertical, a round slot 96 with a width ti of about 1.2 mm is introduced according to Fig. 17 -- inclined at an angle w ₄ of 40° to the vertical. The round slot 96, whose inner diameter d ₃ measures about 14 mm, surrounds a central screw opening 100 with a diameter d ₄ of 6.8 mm here.

In particular, Fig. 15 and 16 show two desk surfaces 97 inclined at an angle y of 15° in the longitudinal direction of the surface 98 of the screw web 92 as well as the curvature of the latter.

The mitred hollow profiles 11 _{a of} square cross-section in Fig. 18, 19, which are cut to a right angle and lie against one another with their inclined edges 102, are held together by a pair of insertion angles 104, 106 of thickness C ₂ made of light metal, which together fill the cross-section of the profile interior spaces 13 in the corner area. Their leg length qi measures 50 mm here with a leg width b ₄ corresponding to the clear profile width a ₂ .

Approximately in the extension of the two inner edges 108 of both insertion angles 104, 106 (lines F in Fig. 20) - in the middle of the width - there is a receiving hole 81 or 81 _a . These are designed as through-holes 81 with inserted threaded bushing 110 made of steel in the insertion angle 104, which clings to the side wall 17 having the opening 15, as can be seen in particular in Fig. 19; the receiving holes 81 _a of the other insertion angle 106 are blind holes, the depth c ₃ of which is approximately half the

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Thickness of the insertion angle 106. Its diameter ds is also shorter than that of the screw holes 81.

After inserting connecting screws (not shown) into the opening 15 as well as the screw hole 81 and the blind hole 81 _a , they are tightened - the angle unit described is assembled.

·

Claims (33)

1. Connecting device for connecting a first workpiece having an interior space ( 22 ), in particular a strand-like hollow profile ( 10 ), to another such workpiece by means of a screw or similar element ( 50 ), the shaft ( 54 , 55 ) of which passes through an opening ( 20 ) of the workpiece and can be inserted into a counter element ( 60 ) in the interior space, characterized in that the shaft ( 54 , 55 ) of the clamping screw ( 50 ) passes through a sleeve ( 36 ) of the connecting device ( 34 ), which is fixed in a longitudinal groove ( 20 ) of one workpiece ( 10 ) in such a way that a threaded area ( 55 ) of the clamping screw projects over the end face ( 14 ) of the workpiece and is provided with a screw head ( 60 ) at a distance from this, said screw head being inserted into an undercut longitudinal groove ( 20 ) of the other workpiece ( 10 ) is designed to be insertable. 2. Connecting device according to claim 1, characterized in that the sleeve ( 36 ) is arranged so as to be detachably fixable in the longitudinal groove ( 20 ) of the workpiece ( 10 ). 3. Connecting device according to claim 1 or 2, characterized in that the sleeve ( 36 ) is connected to the workpiece ( 10 ) by a tongue and groove system ( 32/40 ) running transversely to its longitudinal axis (A). 4. Connecting device according to claim 3, characterized by lateral outer ribs ( 40 ) of the sleeve ( 36 ), with which radial grooves ( 32 ) can be formed in the workpiece ( 10 ). 5. Connecting device according to claim 3, characterized by lateral outer ribs ( 40 ) of the sleeve ( 36 ), which are designed to be insertable in radial grooves ( 32 ) of the workpiece ( 10 ). 6. Connecting device according to claim 4 or 5, characterized in that the cross-sectionally approximately triangular outer rib ( 40 ) with its rib surfaces ( 42 ) merges into forming grooves ( 46 ) of the sleeve outer surface ( 39 ). 7. Connecting device according to claim 6, characterized in that the rib tips ( 41 ) of several outer ribs ( 40 ) run parallel to one another or determine a common ring contour. 8. Connecting device according to one of claims 4 to 7, characterized by at least three groups of outer ribs ( 40 ) parallel to the longitudinal axis (A ₁ ) of the sleeve ( 36 ), which in the fastening position are assigned to radial grooves ( 32 ) and the latter are attached in the deepest part of the groove ( 24 ) and in mutually facing surfaces of shaped ribs ( 18 ) delimiting the longitudinal groove ( 20 ) on the profile side surface ( 16 ). 9. Connecting device according to one of claims 1 to 8, characterized in that a sleeve edge ( 47 ) of the sleeve ( 36 ) fixed in the workpiece ( 10 ) is approximately flush with an end face ( 14 ) of the workpiece. 10. Connecting device according to claim 9, characterized in that a ring ( 48 ) made of elastic material surrounding the threaded region ( 55 ) of the clamping screw ( 50 ) is arranged between the sleeve edge ( 47 ) and the screw head ( 60 ). 11. Connecting device according to claim 9 or 10, characterized in that the screw head ( 52 ) of the clamping screw ( 50 ) rests against the other sleeve edge ( 47 _t ) of the sleeve ( 36 ) in the clamping position. 12. Connecting device according to claim 11, characterized in that the screw head ( 52 ) of the clamping screw ( 50 ) has a blind hole ( 53 ) of polygonal cross-section on the front side. 13. Connecting device according to one of claims 1 to 12, characterized in that the screw head ( 60 ) which can be screwed onto the clamping screw ( 50 ) is plate-shaped, wherein its length (n) is optionally somewhat shorter than the width (f) of the groove space ( 22 ) of the undercut longitudinal groove ( 20 ) which receives it. 14. Connecting device according to one of claims 8 to 13, characterized in that the shaped ribs ( 18 ) delimiting the longitudinal groove ( 20 ) are designed like hooks and the surfaces of the hook ends ( 19 ) directed towards the deepest part of the groove ( 24 ) are designed as abutments for the screw head ( 60 ). 15. Connecting device according to claim 10 and 14, characterized in that the height of the hook ends ( 19 ) approximately corresponds to the height of the ring ( 48 ) made of elastic material mounted between them. 16. Connecting device for connecting a first workpiece having an interior space ( 13 ), in particular a strand-like hollow profile ( 11 ), to another such workpiece by means of a screw or similar element ( 86 ), the shaft ( 96 ) of which passes through an opening ( 15 ) of the workpiece and can be inserted into a counter element ( 92 ) in the interior space, characterized in that a connecting device ( 70 ) touching the inner surfaces of its four side walls (17) is inserted into the interior space ( 13 ) of the workpiece or hollow profile ( 11 ) of rectangular cross-section and is fixed in the hollow profile in such a way that one of its end faces is approximately aligned with one of the end faces ( 14 ) of the hollow profile and a threaded area ( 90 ) of the clamping screw ( 86 ) projects over this end face into the interior space ( 13 ) of the other hollow profile ( 11 ) and is connected there to a Screw web ( 92 ) formed and adjacent to the inner surface of this other hollow profile. 17. Connecting device according to claim 16, characterized in that the connecting device ( 70 ) contains a cross-sectionally cross-shaped shaped piece ( 72 ) and the lateral front edges ( 75 ) of its four shaped piece ribs ( 74 ) are provided with a screw hole ( 80 ) for a screw or screw sleeve ( 82 ) penetrating the side wall ( 17 ) of the hollow profile ( 11 ). 18. Connecting device according to claim 17, characterized in that the lateral front edge ( 75 ) of the shaped piece rib ( 74 ) is provided with at least one groove-like incision ( 78 ) extending transversely to the longitudinal axis (A ₁ ) of the shaped piece ( 72 ). 19. Connecting device according to claim 18, characterized in that the two side walls ( 77 ) of the incision ( 78 ) are inclined at an angle (x) to one another such that the cross section of the incision widens outwards. 20. Connecting device according to claim 18 or 19, characterized in that in the clamping position of the shaped piece ( 72 ) the incision ( 78 ) receives a molding ( 79 ) of the side wall ( 17 ) of the hollow profile ( 11 ), wherein preferably two incisions opposite each other on both sides of the longitudinal axis (A ₁ ) each receive one of the moldings. 21. Connecting device according to one of claims 17 to 20, characterized in that a passage ( 84 ) for a retaining bolt ( 86 ) forming the clamping screw ( 90 ) runs in the longitudinal axis (A ₁ ) of the shaped piece ( 72 ). 22. Connecting device according to claim 17 and 21, characterized in that the screw hole ( 80 ) in the shaped piece rib ( 74 ) opens into the passage ( 84 ) for the retaining bolt ( 86 ). 23. Connecting device according to claim 21 or 22, characterized in that the retaining bolt ( 86 ) contains a threaded bolt ( 90 ) axially formed on a _bolt body ( 87 , 87a ) as a clamping screw. 24. Connecting device according to claim 22 or 23, characterized in that at least one lateral recess ( 89 ) is formed in the bolt body ( 87 ) as a locking element for a screw sleeve ( 82 ) or screw ( Fig. 11, 12) provided in the screw hole ( 80 ) of the shaped piece rib ( 74 ). 25. Connecting device according to claim 22 or 23, characterized in that the bolt body ( 87a ) contains a circumferential constriction ( _Q1 ) delimited by two bolt sections ( 89a ) tapering _in opposite directions as a locking element for a screw sleeve ( 82 ) or screw ( Fig. ₁₃ ) provided in the screw hole ( 80 ) of the shaped piece rib ( 74 ). 26. Connecting device according to one of claims 16 to 25, characterized in that the strip-like screw web ( 92 ) is provided on its lower surface ( 58a ) with a central formation ( 94 ) and in the region of which a central screw opening ( 100 ) is provided for the threaded region ( 90 ) _of the clamping screw ( 86 ). 27. Connecting device according to claim 26, characterized by a round slot ( 96 ) in the region of the central formation ( 94 ) 28. Connecting device according to claim 26 or 27, characterized in that the surface ( 98 ) of the screw web ( 92 ) is curved in a partially circular cross section and/or is provided with two counter-rotating desk surfaces ( 97 ) in longitudinal section. 29. Connecting device for connecting a first workpiece having an interior space ( 13 ), in particular a strand-like hollow profile ( 11a ₎ , to another such workpiece by means of a screw or similar element, the shaft of which passes through an opening ( 15 ) in the workpiece _and can be inserted into a counter element ( 110 ) in the interior space, characterized in that the two workpieces or hollow profiles ( 11a ) of rectangular cross-section are mitred to length and are placed at right angles to one another with their oblique edges ( 102 ), wherein in the corner region of the interior space ( 13 ) at least two parallel insertion angles ( 104 , 106 ) filling the cross-section of the interior space are firmly connected to one another and to the hollow profiles by the screws or similar elements. 30. Connecting device according to claim 29, characterized by two insertion angles ( 104 , 106 ) of approximately the same thickness (c ₂ ), the angle legs of which are each provided with a receiving hole ( 81 , 81 _a ) for screws. 31. Connecting device according to claim 29 or 30, characterized in that one insertion angle ( 104 ) is provided with screw holes ( 81 ) passing through its angle legs as receiving holes and the other insertion angle ( 106 ) is provided with blind holes ( 81a ₎ as receiving tabs ( Fig. 19). 32. Connecting device according to claim 31, characterized in that the screw holes ( 81 ) of one insertion angle ( 104 ) run coaxially to the blind holes ( 81a ) of the other insertion angle ( 106 ) and to openings ( 15 ) in one of the profile side walls ( 17 ) _. 33. Connecting device according to one of claims 1 to 32, characterized by at least one further of the features disclosed in the description and/or drawing.