GB2213188A

GB2213188A - Apparatus for concrete formwork

Info

Publication number: GB2213188A
Application number: GB8825489A
Authority: GB
Inventors: Gerhard Dingler
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-12-01
Filing date: 1988-11-01
Publication date: 1989-08-09
Also published as: GB8825489D0; IT8883541A0; NO884860D0; NO884860L; IT1226204B; EP0318728A2; EP0318728A3; DE3740745A1

Description

APPARATUS FOR CONCRETE FORMWORK This invention relates to an apparatus according for a formwork panel used in the casti-ng or moulding of concrete.

In known apparatus there is provided a rectangular frame, a plurality of transverse bars, and an internally thread device receiving a threaded cylindrical construction bar.

The internally threaded device may be in the form of a nut, which is rigidly connected with the transverse wall remote from the formwork plate, for example by welding. This known apparatus has the following disadvantages: (a) A relatively expensive nut must be used on each occasion.

(b) The nut must be rigidly connected with the transverse wall remote from the formwork plate. This is usually done by welding. The welding operation is an additional item of work, which sometimes is not satisfactory in its result.

(c) If the nut is welded externally onto the transverse wall, it projects outwards and is a nuisance.

(d) If the nut is torn out or its internal thread is damaged, then this position is no longer available for screwing in the construction bar until the formwork panel is sent back to the manufacturer for repair.

(e) The nuts used are relatively short, whereas the construction bars are relatively long, so that sometimes the bar is not guided coaxially to the but. It must be borne in mind that only very coarse fits between internal thread and external thread can be allowed.

When assessing the conditions, it must be remembered that the construction bar is loaded in the range of about 10 kN. This is because it is utilised for securing support frames, aligning rods or the like. Anchor bars of this type are widely used in the formwork business. For example, such bars by the firm Betonmax or the firm Dywidag are known. The slope of the external thread of such construction bars is always the same.

The slope is steep in order that a large stroke or movement can be achieved with a few turns of the bar. The slope is about 180. The core diameter is also always the same, and is about 15 mm.

The objective of the present invention is to provide an apparatus of the initially named type, which overcomes all the disadvantages mentioned but which also permits the system so far in use not to be changed, so that basically no rethinking is required. This is particularly important for the commonly unskilled personnel found on construction sites.

According to the invention there is provided an apparatus for a formwork panel for the casting or moulding of concrete, comprising a rectangular frame composed of frame members of extruded material, e.g. aluminium, a plurality of transverse bars which extend parallel to one another between two parallel frame members, which transverse bars are also extruded from aluminium, which comprise two side walls, parallel at least in partial regions, running perpendicularly to the plane of the formwork panel, which walls continue into a transverse wall remote from the formwork plate, which transverse wall extends at least in partial regions parallel to the plane of the formwork panel, an internally threaded device which possesses internal thread turns at least in partial regions and complementarily to a generally circular cylindrical construction bar formed with an external thread, a hole being provided in the transverse wall coaxial with the internal thread device, which hole can be transversed along its diameter by a construction bar, and a formwork plate encompassed and supported by the frame and supported also by the transverse bars characterised by the following features: (a) The internal wall faces of the side walls of the transverse bars possess, as viewed in cross-section, a shape corresponding to a diameter cross-section through an internal thread, at least to the extent that the surfaces of the internal thread turns are necessary for carrying the external thread of the construction bar, (b) The inwardly projecting - as seen in cross-section ribs that form the projection of the internal thread are co-extruded during the extrusion process and have a constant cross-sectional shape along the entire length of the transverse bars.

By the features of claim 2 the result is achieved that the side walls of the transverse bars, which indeed bear only locally against the outer thread of the construction bar, are not forced apart.

By the features of claim 4, the result is achieved that a part of the edge circumference of a hole drilled through the transverse wall meshes with the opposite zone of the outer thread of the construction bar in load-bearing manner.

By the features of claim 5, the side walls are further stiffened relative to each other and further load-bearing surfaces for the outer thread of the construction bar are obtained. Moreover, the axial guidance is better than that with a single inner transverse wall.

By the features of claim 6, on the one hand ribs have a good fit to the shape of the outer thread of the construction bar and, moreover, this cross-sectional sharp can be easily extruded, because it does not possess any sharp corners, as would be the case for example with a saw tooth or triangular cross-section.

The features of claim 7 have proved highly satisfactory both in respect of extrusion and in respect of the bearing of the outer thread of the construction bar.

By the features of claim 8 sufficient engagement zones are obtained for forces of 1C kS to be reliably withstood.

By the features of claim c, use is made of the height cf the transverse bars commonly used.

By the features of claim 3 it becomes unimportant how the transverse bars are -elded into the frame.

By the features of claim 10, a sufficiently long travel of the construction bar on the one hand and a sufficiently long engagement zone cf internal and external threads are both obtained.

By the features of claim 11, it is unnecessary to lock the clamping nut relative to the construction bar and an integral, strong component is obtained.

By the features of claim 12 the result is achieved that, when the drill is set up, it is automatically located, even later, in the geometrical central plane.

The features of claim 13 have the same result, so that a guide is provided fo th tip of the drill even when it cannot be seen.

By the features of claim 14, a step is taken permitting the use also of the so-called Dywidag construction bars, although they are oval. In any case, one region of the external thread then meshes with the internal thread of the hole.

By the features of claim 15, the suitability of the invention for use with Dywidag construction bars is further improved. Indenendently of the rotated position of the bar, one region of the e:cternal thread then always meshes with one region of the hole in the transverse walls.

By the features of claim 16 the result is achieved that the loadbearing zones between outer thread of construction bar and the flanks of the ribs are of optimum size.

If, with an apparatus constructed according to this invention, the aluminium which of course is outer than the construction bar should tear away, then t retlacement hole can readily be drill alongside.

The invention is now described with reference to a preferred example of embodiment thereof. The figures in the drawing hole Fig.l. The elevation of a formwork panel seen from the outside, Fig.2. A section on the line 2-2 in Fig. 1. The illustration is to the enlarged scale of 2 : 1.

Fig.3. A further enlarged partial view, to a scale 4 : 1, of the region of the ribs that constitute the turns of the internal thread.

Fig.4. The lateral vie of a construction bar with welded-on flange nut, showing the screwee-in condition in broken lines.

Fig.5. A view corresponding to Fig.2, but for a second form of embodiment.

ig.6. A cross-section through a so-called Dywidag bar.

A formwork panel 11 has a rectangular frame 12, consisting of two fairly long, mutually parallel frame members 13, 14 and of two shorter frame members 16, 17, parallel to each other and perpendicular to the former.

The frame 12 is of aluminium. It surrounds and supports in its edge zone a formork plate 18. parallel to the frame members 16, 17, transverse bars 19, 21, are provided like the run-s of a ladder. They are of extruded aluminium, parallel to one another, of equal length and are rigidly welded at their ends to the frame members 13, 14.The transverse bars 19 initially have holes 22, whereas the transverse bars 21 do not have holes. The transverse bars 19, 21 have mutually parallel side !al1s 23, 24 and transverse walls 26, 27, internal with them, the external surface of the transverse all 27 supporting the internal surface of the formwork plate 18.In the transverse wall 26 remote from the formwork late th@re is a hole 28, the diameter of which is slightly larger than the external diameter D of a construction bar 29. In the geometrical central plane 31 of the transverse bar 19 notches 32, 33 are provided, extending over the entire length, in the external faces both of the transverse wall 26 and of the transverse ..all 27. The cross-section according to Fig.2 shows that the inner wall faces 34, 36 have the same appearance as a cross-section drawn through an internal thread.For this purpose, ribs 37, 38, 39, 41, 42 etc. are provided. The base of each groove 46, 47 is 2 mm from the outer surfaces 43, 44, so that the minimum wall thickness is 2 mm.

Each groove base 4-6, 47 is parallel to the one opposite and is at the same distance from the geometrical central plane 31. '-ach groove base 46, 47 is itself plane. ince to this extent the geometry is identical, the configuration will be described in detail by reference only to Fig.3. Each groove base 47 is 3 mm wide. This base is adjoined by an upwardly orientated 450 flank 48 and a 450 flank 49 according to Fig.3, each making W a difference in thickness of 1 mm, so that the parallel distance between the groove base 47 and thc Plateau 51 is 1 mm.

As seen in the vie@ of ig.3, the plateau is 5 mm high, i.e. is 5 mm long in the direction of the thread. The pitch from the centre of groove base 47 to the centre of groove base 47 is, as shown by the arrow 5, lOmm in every case.

The rib 37 is substantidlly shorter than the ribs 39, 42, because the kink starts at a parallel distance of only 2.6 mm from the inner face 54 of the transverse wall 26. After this, the ribs of the side all 24 always repeat in the same pattern.

The ribs 38, 41 and further ribs of the side wall 23 are obtained by drawing the mirror image abcut the geometrical central plane 31 and at the same time shifting upwards by one-half of the length of the arrow 52 according to Fig.2, i.e. by 5 mm.

For the thread to be discussed later, the 45 flanks 49 and their corresponding flanks in the side call 23 constitute the load-bearing surfaces. The parallel distance of the plateau 51 of the side 24 from the corresponding plate cf the side all 23 is 15 mm. This dimension is suitable for the construction bars of the Betonmat and Dy@iday types, still to be discussed further. For other tyres of construction bar@, the dimensions would have to be adapted. accordingly.

About half-way along the length ofthe side walls 23, 24 tseen in the view of Fig 2) there is a transverse wall 56 about 2 mm thick.

This lies at an angle of 180 to the geometrical central lane 31. It has a through aperture 57, the central axis of which lies in the central plane 31. The diameter of the through aperture 57 is somewhat smaller than the diameter of the hole 28, but slightly larger than the core diameter of the construction bar 29. The transverse wall 56 has notches 58, 59 located in the geometrical central plane 31, which serve for centring the drill ti1. The lower face 61 of the transverse wall 56 starts at a kink 62 which forms the transition from a 450 slope to a plateau.

From here the lower face 61 runs at 180 to the right and downwards and there meets the opposite plateau. The upper side 63 starts at a distance of 2 mm,corresponding to the wall thickness, above the kink 62 and also runs at 180 obliquely to the right and down wards. Due to the wall thickness chosen, it does not meet the transition between the 450 flank and plateau, so that the corner 64, shown in Fig.2, results.

The construction bar 29 of th Betonmax the is usually of steel. In the screwed-in condition, its geometrical central axis 66 lies in the geometrical central plane 31. In the view of Fi.. .4, its thread turn 67 appears shifted by 10 mm each time corresponding to the aforementioned pattern. @hen under tensile load, each of its downwardly orientated flanks 68 bears in a region tangential to the 45 flank 49. However, the rear region of the upper side 63 of the transverse wall 56 in Fig.2 also carries load, because there the thread turn 67 lies also at an angle of 18 , although not visible in Fig.4 from the front side but as the complementary angle.The flat circumferential surface 69 of the helical thread 67 is shorter than the base of the groove 46, so that guidance takes place on onc side only. The flan 68 is at 450 to the surface 69 of the helix, which corresponds to the anle of the 450 flanks 4C and 49.

On to the lower end, as seen in Fig.4, of the known construction bar 29, there is screwed a flanged nut 71, of the type DIN 18 216 with thc: further specification of 1590/110. If the construction bar 29 projects a small distance below the flanged nut 71, it is secured there by a weld bead 72. In this position, objects can be clamped with high force firmly between the upper face 73 of the flanged nut 71 and the transverse wall 26.

Claims

1. Apparatus for ~ formwork panel for the casting or moulding of concrete, comprising a rectangular frame composed of frame members of extruded material, e.g.

aluminium, a plurality of transverse bars which extend parallel to one another between two parallel frame members, which transverse bars are also extruded (e.g. from aluminium), which comprise two side walls, parallel at least in partial regions running perpendicularly to the plane of the formwork panel, which walls continue into a transverse wall remote from the formwork plate, which transverse wall extends at least in partial regions parallel to the plane of the formwork panel, an internally threaded device which possesses internal thread turns at least in partial regions and complementarily to a generally circular cylindrical construction bar formed with an external thread, a hole being provided in the transverse wall coaxial with the internal thread device, which hole can be transversed along its diameter by a construction bar, and a formwork plate encompassed and supported by the frame and supported also by the transverse bars, characterised by the following features: (a) The internal wall faces of the side walls of the transverse bars possess, as viewed in cross section, a shape corresponding to a diameter cross-section through an internal thread, at least to the extent that the surfaces of the internal thread turns are necessary for carrying the external thread of the construction bar, (b) The inwardly projecting - as in cross-section ribs that form the projection of the internal thread are co-extruded during the extrusion process and have a constant cross-sectional shape along the entire length of the transverse bars.

2. Apparatus according to claim 1, characterized in that, in the region of this cros-section of the transverse bars, the inner wall faces (side walls) of the transverse bars continue into an inner transverse wall which has a thickness sufficient to prevent forcing alert of the side walls, due to thread forces.

3. Ataratus according to one or more of the Drecedino claims, characterized in that the cross-section of the inner wall faces corresponding to the cross-section of internal thread turns extends throughout the entire height of the inner wall faces.

4. Apparatus according to claim 2, characterized in tha the inner transverse wall is at an angle to the side walls equal to the pitch angle of the internal thread.

5. Apparatus according to claim 2, characterized in that several inner transverse walls are ,rovided.

6. Apparatus according to claim 1, characterised in that the ribs have a cross-sectional form corres--onding to the cross-sectional form of a trapezium-shaped thread.

7. Apparatus according to claim 6, characterized in that the flanks of the ribs are inclined at 450 +25 .

8. Apparatus accordin to claim 1, characterized in that the ribs extend through a height of at least 50 mm.

9. Apparatus according to claim 8, characterized in that the ribs extend over a height of 100 nim + O',t'

10. Apparatus according to claim 1, characterized in that the external thread of the construction bar is So mm to 140 mm long, preferably around 120 mm long

11. Apparatus according to claim 1, characterized in that the external thread of th construction bar is screwed into the internal thread of a clamping nut and is secured there against rotation, esecially is firmly lielded.

12. Apparatus according to claim 1, characterized in that at least the transverse all remote from the formwork plate has a longitudinal notch hich lies in the geometrical central plane of the transverse bar.

13. Apparatus according to claims 2 and 3, characterized in that the transverse , alls possess longitudinal notches which lie in the geometrical central Plane

14. Apparatus according to claim 1, characterized in that the hole possesses an internal thread.

15. Apparatus according to claim 5, characterized in that at least one transverse ":all has a positive slope according to the internal thread slope and at least one transverse wall has a negative slope according to the internal thread sloe.

16. Apparatus according to claims 2 or 5, characterized in that, where holes are drilled in an inner transverse wall, their diameter is slightly larger than the core diameter of the construction bar.

17. Apparatus for a formwork panel for the casting or moulding of concrete substantially as described with reference to the accompanying drawings.