GB2102908A

GB2102908A - Mitre corner connection

Info

Publication number: GB2102908A
Application number: GB08218673A
Authority: GB
Inventors: Wilfried Pretzel
Original assignee: Eduard Hueck GmbH and Co KG
Current assignee: Eduard Hueck GmbH and Co KG
Priority date: 1981-07-01
Filing date: 1982-06-28
Publication date: 1983-02-09
Also published as: ES274558Y; DE3125883A1; NO821829L; DK294182A; ES274558U; BE893702A; FR2508988A1; LU84249A1; NL8202432A; JPS5811284A; DD202333A5; PT75161B; IT8221900A0; DE3125883C2; ZA824667B; AT377643B; GB2102908B; IT1153545B; AU8548982A; ATA308476A

Abstract

Two elongated frame sections (1, 2) are joined in a mitre corner connection, with each frame section having a mitre cut end surface adapted to abut the corresponding mitre cut end surface of the other section, each mitre cut end surface having upper (9, 10) and lower mitre edges running from the inside of the mitre corner to the outside, by providing each frame section with an elongated groove (5, 6) running substantially parallel to one of its upper (9, 10) or lower mitre edges, with a first groove portion with a side open to the mitre cut end surface and aligned with the corresponding open side of the first portion of the corresponding groove in the other frame section, the elongated groove in each frame section further having a second portion (5', 5'', 6', 6'') separated from the mitre cut end surface by a web (11, 11', 12, 12') of material and each elongated groove having an open end, and inserting a clamping member 7 into the first and second portions of the grooves of both sections via their open ends to engage frictionally in the grooves (5, 6) and to positively clamp together the web portions (11, 11', 12, 12'). <IMAGE>

Description

SPECIFICATION Method of mitre corner connection of elongated frame sections, and sections so joined This invention relates to a method of mitre corner connection of elongated frame sections, and sections so joined. Such frame sections are used for window and door frames.

In a mitre corner connection of this type known from German Offenlegungsschrift 24 41 969, there is an insert piece housed in a guideway provided on the insides of the elongated frame sections at each mitre corner where they are joined. The insert piece consists of a substantially flat element extending along the length of the mitre edges and exhibiting a point at one end and an angular incision at its other end. The insert piece is pushed into the guideway provided on the inside of two mutually abutting frame sections of a window frame, so that it bridges the mitre gap, being invisible from the outside of the frame. The surface of the insert piece which bridges the gap is coated with a sealing compound in order to seal the mitre gap. No positive and frictional connection of the frame sections is provided or made possible in the case of this known arrangement.Because the forces which act on a window frame, e.g. due to thermal stresses, wind loads and suction loads, are considerable, the known insert piece is not suitable for ensuring an adequate mechanical absorption of forces beyond its function as a metal sealing strip. A mechanical pressing of the sections together at the mitre cut edges to prevent a mitre gap, which is indispensable in such frames, is likewise not possible.

In another mitre corner connection according to German Gebrauchsmuster 71 46 378, metal elongated sections serving as reinforcement are pushed into the hollow chambers of plastic elongated sections which are initially assembled loosely, and fixed mutually therein. For this purpose two separate insert pieces arranged with a mutual lateral interval are inserted into the cavities of the reinforcing metal sections in each mitre corner between which a gib is driven in in each case from the frame rebate side through an orifice in the outer plastic frame in order to press the two insert pieces together in the mitre cut and to establish a frictional connection between the reinforcing metal sections. The plastic elongated sections are afterwards welded together at the mitre corners.

With this known corner connection it is impossible to draw the mitre cut edges of the inner reinforcing metal sections together and thereby to avoid a mitre gap. Nor is a pressing together of the outer plastic frame sections provided or possible. Furthermore, welding of the plastic frame sections is only possible by complicated special welding methods, The known butt welding (mirror welding) method is not applicable.

It is the aim of the invention to develop a simple mechanical mitre corner connection which is economic to produce, which is universally suitable both for wholly plastic frames as well as for metal frames or combined metal/plastic frames, and by which the occurrence of mitre gaps is prevented.

According to a first aspect of the invention there are provided two elongated frame sections joined in a mitre corner connection, each frame section having a mitre cut end surface adapted to abut the corresponding mitre cut end surface of the other section, each mitre cut end surface having upper and lower mitre edges running from the inside of the mitre corner to the outside, wherein each frame section has an elongated groove running substantially parallel to one of its upper or lower mitre edges, with a first groove portion with a side open to the mitre cut end surface and aligned with the corresponding open side of the first portion of the corresponding groove in the other frame section, the elongated groove in each frame section further having a second portion separated from the mitre cut end surface by a web of material and each elongated groove having an open end, and a clamping member insertable into the first and second portions of the grooves of both sections via their open ends to engage frictionally in the grooves and to positively clamp together the web portions thus forming a bridge positively clamping together the frame sections across their mitre cut end surfaces.

According to a second aspect of the invention there is provided a mitre corner connection for a frame which has a plurality of elongated shaped members provided with mitre end surfaces having mitre edges and arranged so that each two neighbouring shaped members are connected with one another in a respective one of frame corners, the mitre corner connection comprising a guide provided on the mitre end surface of each of the shaped members in each corner and including a formation which forms a guiding recess extending parallel to the mitre edges of the two neighbouring shaped members adjacent to the mitre surfaces of the latter; and an insert receivable in said guiding recess and formed as a clamping member engaging with said formation in form-locking and force-transmitting manner and pressing the two neighbouring shaped members into abutment against one another along their mitre surfaces.

The formations of said guide may be formed by webs of a material of the shaped member, or as holders provided on the shaped member. Normally the guiding recess will be chosen to extend parallel to a mitre edge leading from the inside of the corner to the outside.

According to a third aspect of the invention there is provided a method of mitre corner connection of two elongated frame sections, each frame section having a mitre cut end surface adapted to abut the corresponding mitre cut end surface of the other section, each mitre cut end surface having upper and lower mitre edges running from the inside of the mitre corner to the outside, comprising the steps of forming in each frame section an elongated groove running substantially parallel to one of its upper or lower mitre edges, with a first groove portion with a side open to the mitre cut end surface and aligned with the corresponding open side of the first portion of the corresponding groove in the other frame section, the elongated groove in each frame section further having a second portion separated from the mitre cut end surface by a web of material and each elongated groove having an open end, and inserting a clamping member into the first and second portions of the grooves of both sections via their open ends to engage frictionally in the grooves and to positively clamp together the web portions thus forming a bridge positively clamping together the frame sections across their mitre cut end surfaces. The two frame sections may be assembled together before making the groove in each, and the grooves are then made simultaneously in both sections. Alternatively, the grooves are made prior to assembly.

The proposal according to the invention provides an economical and reliable mitre corner connection, without expensive components, to connect even frame sections of wholly plastic frames together mechanically whilst avoiding a mitre gap for a minimum assembly outlay, so that the welding which is customary for such frame connections can be omitted. This advantage has also been found particularly significant in the case of combined plastic/metal window frames, for which due to their particular structural constitution the welding of the plastic frame by the methods currently known is impossible.

Moreover the solution according to the invention can provide a precise distribution of forces and an adequate absorption in every respect of the internal and external forces acting on the frame corners is ensured.

A particularly uniform distribution of forces is obtained if, according to a preferred feature of the invention, the grooves extend substantially along the length of and closely adjacent to the upper and/or the lower mitre edges of the two sections respectively. This simultaneously creates continuous webs along the mitre cut surface so that a surface pressure distributed uniformly along the mitre cut edges operates when the clamping member is applied.

The grooves are preferable in the walls of the frame rod sections associated with the faces of the frame which when it is in use, as a window or door frame for example, are on the outside and thus visible. Because then the grooves, and hence necessarily the retaining webs, are located in immediate proximity of the outer mitre cut edges, an optimum distribution of forces in the immediate region of the mitre cut edges is ensured and the formation of visible mitre gaps in the frame corners is practically eliminated.

Even firmer clamping is achieved if there is such an elongated groove closely adjacent to each of the upper mitre edges and to each of the lower mitre edges and two clamping members are used at each corner.

The frame sections may be made from hollow box sections, including sections having a plurality of hollow spaces extending along their length, and said first groove portions may be formed by spaces in the box sections, while the second groove portions are cut into the walls of the box sections.

the open entries to the groove ends will also be formed by cutting away part of the walls of the box sections.

The web portions may extend only along one side of the open side of the first groove portion of each groove, or they may extend along both sides of the open side of the first groove portion of each groove.

If the frame sections are formed from elongated hollow complex box sections having two walls on one side spaced from another by a hollow space, the hollow space may form the first portion of the grooves and the second portions can be formed by cutting incisions into one or both of the two walls, to give a web portion either on one side only or on both sides of the open side of the first groove portion.

The second groove portions may have a U-shaped cross-section, or a dove-tailed crosssection.

The ends of the grooves may be open only to the inside of the corner, or alternatively are open only to the outside of the corner, depending on from which side access is easier when the frame has been assembled in position.

A combination of both these embodiments is also possible in the case of a plurality of grooves in one mitre corner. In practice the groove orifices will be provided where they are most easily accessible during erection and/or where they are least disturbing visually in the installed frame.

The clamping member preferably has retaining projections integrally connected via a web bridge, arranged on both sides of the web bridge and projecting with reference to the latter, the crosssections of which correspond substantially to the cross-sectional shape of the second groove portions. By this means a positively guided driving of the integral clamping member into the second groove portions is possible. The clamping member conveniently consists of a harder material compared to the material of the frame sections.

The length of the grooves and thus of the clamping member is advantageously nearly equal to the length of the mitre edges. In order to intensify the positive and frictional engagement between clamping member and grooves, the retaining projections of the clamping member conveniently have additionally a raster-like profiling or the like acting counter to the driving direction of the clamping member.

In order to pack the total cross-sectional length of the grooves, the clamping member advantageously exhibits a contour adapted to the closed groove ends at its front end in the driving direction and a concave angular incision at its rear end, so that on insertion the exposed surfaces of the clamping member are flush with the exposed surfaces of the frame sections.

As the clamping member is preferably a force fit in the grooves, the entry orifice of the clamping part formed between the retaining projections is conveniently widened in cross-section in its leading end region in the insertion directing. The pushing of the clamping member onto the material webs is facilitated in this way, whilst during the actual insertion process of the clamping member, the clamping part is self-centring in the grooves due to the accurate and dimensionally correct guidance.

Particularly for an improved seal of the mitre joint, the clamping member is advantageously fixed additionally in the grooves by an adhesive.

Embodiments of the invention are explained more fully below in conjunction with the accompanying drawings wherein: Fig. 1 shows a window frame in elevation; Fig. 2 shows an enlarged scale detail "A" from Fig. 1 of a frame corner in an exploded perspective view; Fig. 3 shows the mitre corner according to Fig.

2 in the assembled position; Figs. 4 and 5 show various other possible cross-sectional shapes for grooves and clamping members viewed along the line of section lV-lV and V-V in Fig. 3; Fig. 6 shows a frame corner in an exploded view similar to Fig. 2, but with two grooves and two clamping parts; Fig. 7 shows the mitre corner according to Fig.

6 in the assembled position, combined with an inner reinforcing frame connected by a corner angle; Fig. 8 shows a section made along the line VIll-VIll in Fig. 7; Fig. 9 shows a profile cross-section illustrated in perspective, with two grooves which exhibit oppositely arranged entry orifices; Fig. 10 shows the clamping member according to Fig. 2 with a raster-like profiling; Fig. 1 1 shows the mitre corner of a metal frame connected by a corner angle in the assembly position, with a plastic frame applied from one side; and Fig. 12 shows a section made along the line XIl-XIl in Fig. 11.

Fig. 1 illustrates a window frame which has been assembled from individual elongated frame sections 1 to 4 mutually abutting the mitring in the corners.

It is clear from the larger scale perspective illustration of the detail "A" from Fig. 1 which is shown in Fig. 2, that the frame sections 1, 2 each exhibit a groove 5, 6, into which an insert piece or clamping member generally designated 7 can be pushed in the direction of the arrow 8 in order to establish a connection between the two rod sections.

The frame sections 1, 2 as shown are elongated box frame sections with a plurality of joined up box portions enclosing hollow spaces. On the upper side of each frame section 1 there are two spaced walls 1', 1", and similarly there are two spaced walls 2', 2", on the upper side of frame member 2.

The first portions of grooves 5, 6 in the frames 1, 2 respectively are formed by the hollow space between walls 1', 1", and 2', 2" respectively.

Second groove portions 5', 5" and 6', 6" are formed by incisions in the walls 1', 1", 2', 2", respectively. Access is also provided to the grooves from the inside of the corners. The second groove portions 5', 5" and 6', 6" are separated from the mitre cut end surfaces by continuous webs 11, 11' and 12, 12' respectively.

The grooves 5, 6 of two rod sections 1, 2 are arranged in mirror image relationship with reference to upper mitre edges 9, 10 in each case to which upper edges they are parallel. The second groove portions 5', 5", 6', 6" may have the widest variety of cross-sectional shapes, e.g. be of Ushaped (Fig. 4), dove-tail-shaped (Fig. 5), or other construction. In all the exemplary embodiments shown the cut second groove portions are worked into the material of the frame sections in a cutting operation, e.g. by milling, mortising, sawing etc., whilst depending upon the construction of the machining tool used in each case, and depending upon the cross-sectional shape of the frame section, they may be cut only on the inside of walls 1', 2', or also on walls 1", 2 located mutually opposite walls 1', 2'.Whereas in the illustration in Figures 2, 3, 5, 6, 7, 8, incisions in two walls 1', 2' and 1", 2" form part of grooves 5, 6 in each case, the example according to Fig. 4 shows only a single groove incision on the outer inside 1', 2' of the sections 1, 2. If the groove incisions are provided in only one wall of the sections, then it is convenient to choose for this purpose the inside of the frame section wall which in use will be associated with the outside, i.e. the visible face of the frame, so that the groove incision is located as close to the outer and visible mitre edges 9, 10 as possible. The grooves 5, 6 may be milled into the already assembled frame.

This has the advantage that all the grooves of both the frame sections mutually abutting in the mitre corner can be hollowed out of the profile walls in common in one operation, whereby high machining precision is ensured. As an alternative to this, however, it is also possible to work the grooves into the individual frame sections before the assembly of the frame.

As may be seen from the drawing, the grooves 5, 6 extend substantially along the whole length of the mitre edges and are bounded at their sides confronting the mitre cut end surface by continuous material webs 11, 11', 12, 12', which with the assistance of the clamping member 7 permit a positive and frictional connection of the frame sections in each mitre corner.

The preferably integrally constructed clamping member 7 (Figs. 2, 4, 5, 6, 10) has retaining projections 13, 14, 15, 16 (Fig. 2) or 13', 14' (Fig.

4), or 15~18 (Fig. 5), the cross-sectional shape of which corresponds substantially to the crosssectional contours of the grooves, and which are mutually connected by a web bridge 19-22 in each case. The clamping member consists of a harder material in comparison to the material from which the frame sections are produced, and is slightly oversize with reference to the grooves, so that when driven into the grooves it cuts into the material of the sections and thereby ensures an absolutely firm and reliable connection, with which any mitre gaps at the visible faces of the frame sections are practically eliminated. The retaining projections of the clamping member, which project beyond the web bridge, may additionally have, as seen in Fig. 10, a raster-like profiling, e.g. saw teeth 23, acting counter to the driving direction.The insertion of the clamping member into the grooves is facilitated in that the entry orifice 24 is widened or oversize in its leading end region in the driving direction with reference to the following guide channel 25 bounded by the retaining projections, so that the retaining projections 13-1 6 or 13', 14' can ride positively and gently onto the material webs 11, 1 1', or 12, 12', or 13', 14' before they become firmly connected to the latter.

The type of clamping member shown in Fig. 10, has a front point 26 adapted to the mitre angle, and it exhibits an angular incision 27 at its rear end. The front point may also be rounded or otherwise constructed depending upon the construction of the groove ends in the rod sections. The contour configuration of the ends of the clamping member serves primarily the purpose of packing the grooves of the frame sections along their total length when the clamping member is inserted.

Whereas in the example according to Figs. 2, 3, 6, 7, 8, 9, 12 the entry orifice of the grooves 5, 6 is placed on the inside of the frame corner, so that the clamping part can be driven into the groove from the inside of the corner, it is obviously also possible to provide the entry orifice on the opposite side, i.e. on the outside of the frame corner. The entry orifice is conveniently, as far as possible, arranged where it is not visually disturbing in each case.

It is also possible, instead of only one groove/clamping member connection at each frame corner, to provide two, as shown in Figs. 6, 7, 8, 9 or even more such connections which are arranged at spaced intervals and of which at least two groove/clamping member connections are provided in proximity of the frame outer surfaces in order to ensure a uniform distribution of forces.

In the case of such an arrangement it is also possible, as in the example according to Fig. 9, to provide the entry orifice of the one groove 5 on the inside of the corner of the frame and that of the second one on the opposite frame side.

Whereas the example according to Figs. 2, 3 is intended to represent the corner of a wholly plastic frame, in which the frame sections are held together exclusively by a corner connection according to the invention, the embodiment according to Figs. 7-9 illustrates that the corner connection according to the invention is applicable in the same manner if the plastic sections are additionally reinforced by inner reinforcing sections 28, 29 made of metal, whilst the latter may be connected by corner angles 30 at the mitre corners in known manner.

Another exemplary application of the corner connection according to the invention is shown in Figs. 1 1 and 12. In this example plastic frame sections 31, 32 are applied from one side of the frame to a metal frame 33, 34 connected by known corner angles 30 in the mitre corners, so that a combined metal/plastic frame results. In the case of this type of frame the plastic sections 31, 32 are secured to each other only by the corner connection according to the invention at the mitre cut edges. No additional welding of the plastic sections is necessary.

Claims

1. Two elongated frame sections joined in a mitre corner connection, each frame section having a mitre cut end surface adapted to abut the corresponding mitre cut end surface of the other section, each mitre cut end surface having upper and lower mitre edges running from the inside of the mitre corner to the outside, wherein each frame section has an elongated groove running substantially parallel to one of its upper or lower mitre edges, with a first groove portion with a side open to the mitre cut end surface and aligned with the corresponding open side of the first portion of the corresponding groove in the other frame section, the elongated groove in each frame section further having a second portion separated from the mitre cut end surface by a web of material and each elongated groove having an open end, and a clamping member insertable into the first and second portions of the grooves of both sections via their open ends to engage frictionally in the grooves and to positively clamp together the web portions thus forming a bridge positively clamping together the frame sections across their mitre cut end surfaces.

2. Joined frame sections according to claim 1 wherein the grooves extend substantially along the length of and closely adjacent to the upper or the lower mitre edges of the two sections respectively.

3. Joined frame sections according to claim 1 or claim 2 wherein there is such an elongated groove closely adjacent to each of the upper mitre edges and to each of the lower mitre edges and two clamping members are used.

4. Joined frame sections according to any one of claims 1 to 3, wherein the frame sections are made from hollow box sections and said first groove portions are formed by spaces in the box sections while the second groove portions are cut into the walls of the box sections.

5. Joined frame sections according to any preceding claim wherein the web portions extend only along one side of the open side of the first groove portion of each groove.

6. Joined frame sections according to one of claims 1 to 4, wherein the web portions extend along both sides of the open side of the first groove portion of each groove.

7. Joined frame sections according to one of claims 1 to 6, wherein the second groove portions have a U-shaped cross section.

8. Joined frame sections according to one of claims 1 to 6, wherein the second groove portions have a dove-tailed cross-section.

9. Joined frame sections according to one of claims 1 to 8, wherein the ends of the grooves are open only to the inside of the corner.

10. Joined frame sections according to one of claims 1 to 8, wherein the ends of the grooves are open only to the outside of the corner.

11. Joined frame sections according to any preceding claim wherein the cross-section of the clamping member corresponds substantially to the combined cross-section of the grooves in both frame sections.

12. Joined frame sections according to any preceding claim, wherein the clamping member is made of a harder material than that of the sections.

13. Joined frame sections according to claim 2, wherein the length of the clamping member is approximately equal to the length of the upper or lower mitre edge respectively.

14. Joined frame sections according to any preceding claim, wherein the portions of the clamping member which engage into the second groove portions have a raster-like profiling acting counter to the direction of insertion of the clamping member.

15. Joined frame sections according to any preceding claim, wherein the clamping member has a contour adapted to the groove ends at its front end in the insertion direction and a concave angular incision at its rear end.

16. Joined frame sections according to any of claims 1 to 15, wherein the entry orifice for the clamping member at the open ends of the grooves is oversize.

17. Joined frame sections according to any preceding claim wherein the clamping member is also held in the grooves by adhesive.

18. Joined frame sections substantially as hereinbefore described with reference to the embodiment of Figures 2 and 3, or 4, or 5, or 6, 7 and 8, or 9, or 10, or 1 1 and 12 of the accompanying drawings.

19. A frame comprising a plurality of frame sections each joined to another at its two ends, with each pair of joined frame sections being joined in a mitre corner connection according to one of claims 1 to 18.

20. Method of mitre corner connection of two elongated frame sections, each frame section having a mitre cut end surface adapted to abut the corresponding mitre cut end surface of the other section, each mitre cut end surface having upper and lower mitre edges running from the inside of the mitre corner to the outside, comprising the steps of forming in each frame section an elongated groove running substantially parallel to one of its upper or lower mitre edges, with a first groove portion with a side open to the mitre cut end surface and aligned with the corresponding open side of the first portion of the corresponding groove in the other frame section, the elongated groove in each frame section further having a second portion separated from the mitre cut end surface by a web of material and each elongated groove having an open end, and inserting a clamping member into the first and second portions of the grooves of both sections via their open ends to engage frictionally in the grooves and to positively clamp together the web portions thus forming a bridge positively clamping together the frame sections across their mitre cut end surfaces.

21. Method according to claim 20 wherein the two frame sections are assembled together before making the groove in each, and the grooves are made simultaneously in both sections.

22. Method according to claim 20, wherein the grooves are made prior to assembly.

23. A mitre corner connection for a frame which has a plurality of elongated shaped members provided with mitre end surfaces having mitre edges and arranged so that each two neighbouring shaped members are connected with one another in a respective one of frame corners, the mitre corner connection comprising: a guide provided on the mitre end surface of each of the shaped members in each corner and including a formation which forms a guiding recess extending parallel to the mitre edges of the two neighbouring shaped members adjacent to the mitre surfaces of the latter; and an insert receivable in said guiding recess and formed as a clamping member engaging with said formation in form-locking and force-transmitting manner and pressing the two neighbouring shaped members into abutment against one another along their mitre surfaces.

24. A mitre corner connection according to claim 23 wherein said formations of said guide are formed by webs of a material of the shaped member.

25. A mitre corner connection according to claim 23 wherein said formations are formed as holders provided on the shaped member.