CA1039483A - Manufacture of hollow panels with embedded web strips - Google Patents

Abstract

Abstract of the Disclosure Construction elements comprising two parallel nailable plates interconnected by corrugated metallic web sheets extending edgewise between them and having teeth at their edges embedded in the plates are commercially manufactured as follows in a machinery designed for the purpose: The bottom plate is placed in a movable frame equipped with displaceable abutments connected to clamping means. The strips are placed in positions so as to be clamped by the said means at their extremities, the extremities of longitudinal strips being pinched in folds of transversal end strips. Thereby also interlocking deformations are punched in the adjoining webs. The clamping means are moved for stretched the strips, the upper plate is placed on top, and web strips are plates are brought into correct relative positions by corresponding positioning of the abutments. In addition longitudinal web strips extending along edges of the element are supported externally between clamping points by spring-loaded rulers connected to abutments so as to ensure correct spacing from the plate edges. With the components of the element thus aligned the frame is moved into a press and the components pressed together, the abutments yielding vertically against spring-load. Then the frame with the element is removed from the press, and the grip by the abutments and clamping means released. For permitting stepwise pressing of elements longer than the press the latter has a smoothly converging entrance portion. In its preferred form the web sheet has a largely trapezoidal corrugation, a z-shaped cross-section of the teeth and shallow depressions between the consecutive teeth, suited as starting points for folds to be formed.

Description

~(~39~83 The invention relates to construction elements of the kind com-prising two plates o~ nailable material and web strips that hold the plates together in spaced apart relationship and consist of elongated sinuous sheet metal strips which along the longitudinal edges are shaped with teeth which are e~bedded in the respective plates, and the invention consists in a method and a machine for the manufacture of such elements on a commercial scale.
More particularly the invention is concerned with the manufacture of construction elements of the kind described in Norwegian patent 129,759 and Canadian patent application 162,388, and which in a preferred embodiment has the form of a closed box with bottom and top (flange plates) of a nail-; able plate material such as plywood, particle board or fibre board. The side walls ~webs) of the element consist of sheet metal strip, such as galvanized steel, which is bent or corrugated in the transverse direction and shaped wlth dowel-like teeth along its longitudinal edges. The element is assembled in a pressing operation whereby the teeth of the web strips are pressed into the plates so as to provide a connection of considerable strength and stiffness.
In pre~ious publications relating to structures of the above kind, such as German published patent specification No. 1,004,790 and U.S. patent specification No. 3,538,668, nothing is said about how such elements may be produced, and especially how ~he web strips prior to the pressing operation can be held in their proper positions with a predetermined distance between the edges of the plates and the web strips, how completely closed elements should be manufactured, or how long elements may be pressed with a short press. As pointed out in applicant's

-2-~39~3 above mentioned patent application, the shapes of web strips and teeth disclosed in the abovementioned previous publications, are not suitable for use in load-bearing elements and, as far as is known, have never found any practical use.
Load-bearing elements of the kind mentioned in the preamble, may in particular be used as floor and roof elements in smaller building such as residential houses, and will thereforè have a place in modern commercial housing manufacture. It is feasible to manufacture such elements in modular dimensions, for example in widths of 60 and 120 cm, if desired up to 240 cm, and in lengths up to 12 m.
For the bottom and top o~ a box-shaped panel element, particle board is a suitable material, because it is cheap and is produced in large sizes and at the present time also in qualities suit~ble for use in load-bearing components.
Very high dimensional precision is required if such elements are to be installed on the building site without appreciable finishing work such as sanding or puttying and form a sub-floor upon which floor covering such as linoleum or carpets are to be laid.
In order to ensure such dimensional precision and hence a correct fit between individual panels, the manufacturing method will have to meet a number of conditions which will be discussed briefly below.
Firstly, the web strips must be placed and kept in correct positions prior to the pressing operation. This means that they must be placed vertically between the bottom and top plates and stand straight along the plate edges, in the sense that the extreme points of the corrugated contour lie on a straight line which is parallel to the plate edges at a certain specified distance from these. Deviations ~L0394~3 in this respect complicate the sealing and connection between adjacent elements and give the finished elements an unsatisfactory appearance.
Secondly, the top and bottom plates should be held in correct relative positions so that the plate edges are at all points aligned in the vertical direction. If one plate is displaced relatively to the other, problems will arise when the elements are to be installed and joined, since there will appear unsightly clearances between adjacent top or bottom plates. Actually, the mutual displacements between top and bottom plates should at no point exceed 1 mm, a requirement which for elements of a length of, say, 8 m or more, call for rather rigorous measures.
Thirdly, the total height (thickness) of the panel a~ter pressing should be kept within very close tolerances, for example ~ 0.2 mm. Larger deviations in this dimension give anoticable step in the joint between adjacent elements and call for additional finishing operations on the building site.
Fourthly, it is of considerable practical importance that the production machinery can quickly and simply be adjusted from one~
element size to another. This consideration applies to the length as well as to the width of the element and, to a smàller extent, also to the height.
Further, for the manufacture of large elements, it is important, that the pressing of the element does not call for a press which is as long as the element itself, since a press of for example 12 m length would be very demanding with regard to both cost and space and, besides, could not be utilized to its full capacity.

1039~83 The present invention provides a method for the commercial manu-facture of construction elements of the kind described above, which permits elements of large si~es to be produced in a rational manner and with very good dimensional accuracy. Further, the invention provides a machinery for the manufacture of panel elements according to the method of the invention.
The method for the manufacture of construction elements according to the invention chiefly consists in using web strips which are somewhat underdimensioned relative to their length in the finished element, and in gripping the web strips with displaceably mounted gripping means and then mutually displace the gripping means so as to stretch the web strips in their respective length directions to their respective correct lengths by moving the gripping means relative to each other, whereafter the web strips and the ~op and bottom plates of the elements are brought into mutually correct posi-tions and pressed together.
The machinery of the invention is able to carry out the aforemen-tioned method and comprises meanæ for assembling the plates and web strips, a press for pressing the resulting assembly together, and means for conveying the assembly into and out of the press, wherein said assembly includes means to grip the end portions of the web strips, said gripping means being mounted on a supporting structure and displaceable relative to each other, said gripping means in u~e being moved relative to each other in the respective i length directions of the web strips, thereby stretching these web strips to their desired lengths, said gripping means also holding the web strips in a stretched condition during the pressing operation, and locating means for mutual vertical alignment of the element plates and stretched web strips.
Thus, the invention makes it possible to ensure that warps and unintentional curvatures in the web strips are eliminated and that the individual parts of the panel element are held in correct mutual ~3948;~
positions during pressing and in such a way as to afford a high dimensional precision, and also permits the production to be carried out quickly and efficiently.
The invention also permits long elements to be produced with the use of a relatively short press, by pressing such long elements in several stages and using press plates which are shaped with slightly convergent en-trance zones which form a smooth transition between that part of the element which is completely pressed and that part of the elements which have not yet been pressed.
The method according to the invention may conceivably be carried : i out with a large variety of means. Thus~ the mentioned gripping- and cen-tering means may be mounted on an endless chain, whereby the individual parts of the element are moved to a pressing site where the chain is held under tension, and from where this chain thereafter moves the finished element out. However, it is preferred to use a rigid frame on which the gripping and centering means are mounted for mutual displacement, so that by mutually displacing these means the web strips can be stretched and the plates can be brought into correct positions relative to the web strips and to each other..
The new form Or web strip preferably used in the new method i~
characterized in that the longitudinal portions of the strip extending be-tween the teeth have a shallow troughlike transverse depression which in ad-dition to stiffening these portions is suitable for being engaged by clamp-ing means for being clamped onto the extremity of an ad~oining web strlp.
Further, the new strips are preferably formed as a further developement of the strips shown in the said patent application ~o. 162 388, in which the corrugations are largely trape~oidal and the teeth are largely Z-shaped in cross-section. The corrugations of the web strip may conveniently be adapt-ed to the constructions module in lO0 mm.
Further Yeatures and advantages of the method, machinery and web strip according to the invention will appear from the following detailed description of a preferred embodiment in which reference is made to the ac-compan~ing drawings, in which :~C139483 Figure 1 is a perspective view of a box-shaped panel element of the type described above.
Figure 2 is a diagrammatic plan view of the elements, showing the location of the web strips within the element shown on Figure 1.
- Figure 3 is an elevational view of the edge portion of a blank for the web strips prior to being bent to the corrugated shape.
Figure 4 shows the web strips in section along the line 4-4 on Figure 3 after corrugation.
Figure 5a-c shows diagra~matically in horizontal section three different stages of the formation of a fold connection between two web strips meeting at a right angle.
Figure 6 shows in horizontal section the connection between lon-gitudinal and transversal web strips in the elements in Figure 1.
Figure 7 shows in perspective view and on an enlarged scale a de-formation connection between ]ongitudinal a~d transversal web strips.
Figure 8 is a broken plan view of a jig frame for the se-tting up of an element for pressing.
Figure 9 shows on an enlarged scale a vertical section on the line ~' 9-9 in Figure 8.
Figures 10 to 12 show certai~ details on a movable crossbeam for the jig in plan, elevation and vertical section 12-12 in Figure 11, respec-tively.
Figure 13 is a plan view of a clamping unit on the jig.
Figure 14 is an elevational view of the unit shown in Figure 13 with certain parts omitted for the sake of clarity.
."
Figure 15 shows a vertical section on the line 15-15 in Figure 13.
Figure 16 is an elevational view showing diagra~matically a detail of the clamping unit in Figure 13.
Figure 17 shows in a broken plan view the attachment of a movable 30 side rail to the ~ig ~rame.
Figure 18 shows a vertical section on line 18-18 in Figure 17.
Figure 19 shows in vertical section means for external support of ~)3~33 a longitudinal web strip~
Figures 20 and 21 are diagrammatic views showing in elevation and plan, respectively, a manufacturing plant for the elements.
Figure 22 shows on an enlarged scale a wheel and roller track in cross-section along line 22-22 in Figure 21.
Figure 23 shows enlarged and somewhat exaggerated the shape o~
the entrance end of the press plates in longitudinal vertical section.
Figure 24a-d are diagrammatic elevational views showing different stages of a stepwise pressing of long elements.
DETAILED DESCRIPTIO~ OF THE PREFERRED EMBODIME~T
Figures 1 and 2 show a box-shaped panei element 1 consisting of a lower plate 2, a top plate 3, longitudinal web strips 4, 4' and transversal end web strips 5, which are locked to the longitudinal strips 4, 4' by de-formation connections indicated at 21. In Figure 2 is seen the positions of the web strips in the element 1. The element thus forms a closed box and may be filled with mineral wool or other suitable insulating material. The top and bottom plates 3, 2 (flange plates) may be of particle board or ply-wood with a thickness of for example 10-20 mm, and the element height (thickness) may be typically 15-30 cm, the width 1,20 m or more and a length up to 12 m.~
A typical web strip for the element in Figure 1 is shown in a bro-ken view in Figures 3 and 4 Figure 3 shows a portion of the longitudinal edge of the web strip in flat condition, i.e. before the strip is bent along transverse fold lines into the profile shown in Figure 4. The basic shape is a shallow trapezoidal corrugation with rather wide teeth which are locat-ed in such a way that they acquire a Z-shaped cross-section. The parallel, longitudinal portions 10 of the said profile are near the transition to the transverse portions 11 shaped with a stiffening groove 12, which primarily serves to afford a local stiffening of the flange portion 13, 13' of the Z-shaped teeth, which can thereby be made relatively wide without the freeedges Y, Y' of the tooth buckling while being pressed into the flange plates.
The wide flange portion of the tooth contributes considerably to the bending 1039~g3 strength of the tooth in a direction transversely to the transverse portion 11 and also serves to give the tooth an increased pull-out anchoring strength by providing a larger tooth area as compared to a tooth with a simple Z-profile.
Symmetrically about the transversal planes of symmetry 15, 15' be-tween subsequent teeth, the longitudinal portions 10 are shaped with shal-low, troughlike depressions 17. The object of these is firstly to provide a local stiffening of the portions 1, which due to their relatively large width might otherwise be subject to buckling during the pressing. Secondly, such a trough-shaped depression 17 may serve~as a starting point for a nar-row fold within which a transversely adjoining web strip may be connected tothe web strip 5.
This is shown in Figures 5a-c. By means of a pair of jaws 25 which can be moved towards each other, and which clamp the side edges 19 of the trough, the latter is being pinched together into a narrow fold 17', in-to which a web strip 4 meeting at right angles can be inserted and locked to the web strip 5 with rivets, spot welds, or by a deformation connection as described below with reference to Figures 7 and 13.
Figure 6 shows how the longitudinal web strips ~, 4' are connected to the transversal strips through folding connections 20, 20' as described above. The web strips are furthermore locked together by a number of de-formation connections 21 as shown in detail in Figure 7. The lock 21 is formed by punching or shearing in the plnched fold 17' a loop-shaped pro-truding portion 23, the three layers of sheet metal being cut along lines 22, 22' and the intermediate portion 23 being pressed out in the shape of a shallow loop. Thereby vertical forces V may be transferred between the web strips 4 and 5 through the mutual abutting contact between the sheared faces in the respective strips.
This force transferring connection between the longitudinal web strips 4, 4~ and the transversal strips 5 gi~es the element 1 a consid-erable torsional strength and makes it possible to support the element at the ends in points located away from the longitudinal web strips, so that _ g _ 1C1 3~83 the elements can extend freely across window openings in the supporting wall.
The web strips are preferably made from hot galvanized sheet steel of 0.5 mm thickness. The trapezoidal corrugation profile shown having a Z-shaped tooth profile and stiffening grooves 12 and trough-like depressions 17 enables the web strips to be produced with a period length (distance be-tween the symmetry lines 15, 15 for similarly oriented trapezia) of about 100 mm without the tooth being bent or the web strips buckling during the pressing operation. In practice, a period length o~ approximately 95 mm may be chosen, since the strip, as subsequently explained, is to be stretch-ed about 5% when set up in the jig.
This has the great practical advantage that when, from a coil of ; web strip, a strip for an element of say 6 m length is to be cut, it is not necessary to measure this length, as it is sufficient simply to pass the strip through a colmting device which counts 80 periods and thereafter cuts the strip along a line of symmetry 15. This strip will then have a length ; of about 760 cm and be stretched in the jig to 795 cm, leaving at either end of the element a distance of 25 mm between the web strip and the plate edges.
Wlth regard to the transversal end strips, the same procedure maybe followed, the formation o~ the rold 17' providing a desirable additional shortening which is necessary since in this case the edge distance of 25 mm at either end in relation to the short strip length requires the web strip to be underdimensioned somewhat more than 5%. The formation of the fold 17' may concelvably be effected in the stressing jig by arranging the jaws of the clamping units to have a sufficient stroke length to clamp the trough-shaped depressions 17. Normally, however, it will be more practical and will in the following description be presumed that the folds 17' are formed in a prior, separate operation, so that also the end web strips are suitably underdimensioned when they are mounted in the jig.
A pre-requisite for employing a period length of lOO mm for web strips with such a small material thickness as 0.5 mm, is, however, that longitudinal portions 10 are stiffened as explained above. This development of the si~lple trape~oidal profile which is shown in the above mentioned

3~3 Canadian application 162 388, Figure 13, therefore constitutes a very con-9 iderable improve~ent.
There will now be described a tensioning frame or jig for the set-ting up of elements for pressing. I'he jig is shown diagrammatically in its main features in ~igure 8, and further details are shown in Figures 9 to 19.
The jig 30 has the shape of a frame consisting of a pair of lon-gitudinal beams 31, preferably in the form of rectangular hollow sections, rigidly connected to end beams 32, for example of fla~ steel. The frame has a bottom plate 33 (Figure 9) which may be a thin steel plate. The bot-tom plate is connected to the longitudinal beams 31 through bolts 34, whichcan move vertically in guides 35 fixed to the beams 31. The plate 33 iB
fixed to the bolts 34 with screws, and can therefore be lifted relative to the beams 31. In its lowermost position the plate 33 rests on the guides or sleeves 35, the top of the beams 31, as shown on Figure 9. On the out-side of each beam 31 there are attached a toothed rack 36 and a guide rail 37, for example in the shape of a steel round which at intervals is attached to T-shaped brackets 38, which in turn are attached to the beams 31 with screws or in other suitable means (not shown).
The fra~e 30 further includes a pair of mutually movable transoms 40, one of which (to the right in Figure 8) is preferably fixed near one end of the frame while the other is mounted movably along the frame. On the transoms 40 are placed clamping units 70, 70', in which the transversal and longitudinal web strips can be clamped and locked together. The clamping units 70 can be moved along the transoms and thereby stretch the end web strip 5, and by moving the movable transom 40 in a direction away from the fixed transom, preferably by means of a driving unit 50 with motor, the lon-gitudinal strips 4 can be stretched.
Still further, the frame 30 includes a pair of longitudinal rails 120, 120', which are placed inside the beams 31 and can be moved translat-orily and synchronously towards and away from each other. On the side rails120, 120' are placed detachable holding means 140, which carry aligning rulers 160. These rulers 160 support the longitudinal strips 4 externally ~3g~3 and ensure, together with the holders 140, that the external web strips 4 remain upright in a straight line parallel to and correctly spaced from the longitudinal edges of the plates.
The frame 30 has such dimensions that the largest possible dis-tance between the transoms 40 is somewhat greater than the greatest element length contemplated and the maximum possible distance between the opposite edges of the aligning rulers 160 is somewhat larger than the greatest element width to be considered.
In Figures 10 to 12 is seen a number of details of the movable transom 40. This transom consists of two steel bars 41 (tubular if desired) extending across the ~ig throughout the width of the latter. The steel rods 41 are in each end fixed to a block 42 which can move somewhat in the verti-cal direction on a guiding post 43, preferably with a ball bushing or sleeve 44. The guiding post 43 is rigidly mounted in a block 45, in which also an open ball bushing 46 is mounted which runs on the steel bar 3~. Further the block 45 is also through a side plate 47 rigidly connected to another open ball bushing 46', which together with the side plate 47 carries a hor-izontal mounting plate 48 ~or the driving unit 50. The driving unit 50 in-cludes a motor 51 with a suitable reduction gear, the driven shaft of which carries a gear 52, which through another gear 53 and a suitable disconnect-able coupling 54 drives a shaft 55 which extends throughout the width of the jig 30. The shaft 55 is near its ends journalled in suitable bearings 56 and 57 and carries sprocket wheels 58 at its ends. Each of the sprocket wheels 58 drives a lower sprocket wheel 59 through a short chain drive 61.
The sprocket wheel 59 is mounted on a short shaft 62 which in a suitable way is ~ournalled on the bottom side of the mounting plate 48, and which on its other end carries a gear 53 which meshes with the tooth rack 36.
In the other end of the movable transom 40, the arrangement is in principle as shown in Figures 10 to 12~ ho~ever, without the driving unit 50, the gears 52, 53 and the coupling 54.
With the arrangement shown on Figures 10 to 12, the transom 40 can move back and forth along the Jig frame 30, and due to the two gears 36 1(~3~3 which run synchronously on the racks 36, the transom will always be exactly at right angles to the length direction of the frame. The coupling 54 may preferably be of the electromagnetic friction type which protects the driv-ing unit from over-loading, and which disconnects the transom gears from the motor when the current to the motor 51 is interrupted. Thereby, the transom 40 can easily be moved manually back and forth along the ~ig frame for quick ad~ustment, whereas the motor 51 is used when the web strips 4, 4' are to be tensioned.
The clamping units for the web strips 47 5 will now be described ~ 10 with reference to Figures 13 to 16, which show such a clamping unit 70. As ; shown, this unit consists of a box 71 open at the top and the bottom and having holes in the side walls 72 permitting the box to slide guidedly along the rods 41 of the transom 40. On the front wall 73 of the box a plate 74 is supported for movement along the wall 73 via T-grooves and rails 77 as shown in cross-section in Figure 15. Furthermore, a second plate 75 is fixed on the front wall 73. To the movable plate 74 and the fixed plate 75 a pair of jaws 76, 76' are fixed with screws. The position of the jaw 76 relative to the plate 74 can be regulated somewhat by means of a couple of adjusting screws 79 engaging screw-threaded bores in a reaction plate 78 on the plate 74, the holes for the fixing screws in the jaw 76 being shaped somewhat ob-long (not shown) in order to allow for horizontal adjustment. For reasons of clarity, the parts 76-78 are not shown on Figure 14.
The plate 74 with the jaw 76 can be displaced towards and away from the fixed jaw 76' by means of a shaft 81 which carries a hand lever 82 and extends through the box 71 between the rods 41, and which is journalled, preferably in needle bearings, in the front wall 73 and the opposite wall 73' of the box. The forward end portion of the shaft 81 is shaped as a crank or circular eccentric 81' which moves the plate 74 horizontally through a bronze block 83, which can move with vertical guidance in a rec-tangular hole 84 in the plate 74, as shown in Figure 14. Thereby a rotation of 180 of the shaftn81 with the handle 82 will move the jaw 76 from the closed position shown in Figure 13 to an open position.
- 13 ~

~039~3 In the movable jaw 76 are mounted punching elements 85, and in the fixed jaw 76' are formed corresponding recesses or grooves ô6 (Figures 13 and 15) for the formation of the deformation connections as shown in Fig-ure 7.
The parts of the clamping unit 70 so far described are sufficient for clamp and locking together longitudinal and transversal web strips. In the form of the jig shown in Figure 8, with three such clamping units on each transom, the central units 70' have only this function, and these units therefore do not need to include further parts than those described so far.
These units are fixed on the transoms l~o, for example with a set screw 87 (Figure 13).
The outer clamping units 70 have also the function to stretch the transversal strips 5 and therefore have to be somewhat movable along the re-spective transoms 40. This stretching movement takes place through a cam element 91 (Figures 13, 15 and 16) which is fixed to the shaft 81 and pushes against the one or the other side wall 92, 92' of a U-shaped element 90 which is fi~ed to the transom rod 41 with a pin 93 (Figure 15), which extends into a bore in the rod 41.
The cam element 91 is shaped so that the clamping unit 70 performs its entire movement for stretching the end strip 5 during the first approx-imately 90 rotation of the shaft 81 from a starting position where the jaws 76, 76' are in the open position. During the remaining part of the rotation of the shaft it is only the jaw 76 that moves in order to clamp the trans-verse web strip to the extremity of the longitudinal strip. ~his is neces-sary in order that when the element has been pressed, it be possible to loos-en the jaws sufficiently to move the transoms from each other so as to per-mit the element to be lifted out of the ~ig frame.
In addition to the described gripping devices the units 70 are al-so equipped with aligning or locating means for locating the top and bottom plates of the element so that these plates will lie in correct positions in relation to each other and also to the web strips. As shown in Figures 13 and 1~ and as described below, this function i8 performed by means of two ~C~394~3 sets of vertically movable, spring-loaded abutting pins which engage the plate edges and prevent the plates from moving out of position in a trans-verse as well as in a longitudinal direction.
To the plate 73 there is fixed a tube lO0 accomodating a pair of vertical pins lOl, lOl' and an intermediate compression spring 102. Verti-cal movements of the pins are limited by stopping pegs 103, 103', running in slots 104, 104' in the tube lO0. The pins lOl, lO1' as well as correspond-ing pins on the opposite transom engage the terminal edge of the top and bot-tom plates, respectively, and ensure that these edges remain aligned verti-cally and do not move out of position. Due to the pins being able to be pushed into the tube lO0, they can follow the movement of the flange plates of the construction element when these are pressed onto the web strips.
In order that after the bottom plate of the element has been placed on the bottom plate 33 of the jig with one edge abutting the lower locating pins of the fixed transom 40, the movable transom 40 can be dis-; placed somewhat inwards over the element bottom plate, so that the under-dimensioned web strips 4, 4' can be placed in the clamping units 70, 70', the lower locating pin 101' is adapted to be lifted by a lever 105 pivoted on an axis in a point A (Figures 13, 15 and 16) on the front wall 73. The 20 lever 105 bears against the peg 103' and against the cam element 91 so that the latter upon the rotation of the shaft 81 can cause lifting of the pin 101' against the pressure of the spring 102. When the unit 70 is closed and tensioned (i.e. the jaw 75 is in the position to the right as shown in Fig-ure 13), the position of the lever 105 is as shown in full lines in Figure 16. When the shaft 81 is rotated 180 back to the starting position, so that the unit moves to the left and the ~aws open, the peg 103' and hence the locating pin 101' are li~ted as shown in dash-and-dot lines in Figure 16.
For the lateral location of the plates of the elements a plate 115 is journalled on a shaft 116 in the plate 75 (only shown in Figure 13) which plate 115 carries a vertical tube llO similar to the tube lO0 and containing correspondingly mounted upper and lower abutting pins, of which the upper pin lll is seen in Figure 13. A spring 117 urges the plate 115 with the :~03~31415 ;~
tube llO out towards the open position as shown in the drawing. The plate115 with the tube 110 is urged into closed position when the movable side rail 120 (Figure 8) is moved towards a lug ll9 on the plate 115 until a stop screw 118 threaded into the plate 115, engages the Jaw 76'. By this arrange-ment it is ensured that the side edges of the flange plates will remain aligned in the vertical plane and at a predetermined distance from the lon-gitudinal strips 4.
In the event that it is not desired that the edges of the flange plates shall be aligned, for example if the upper plate is shaped with a tongue along one edge and a corresponding groove along the opposite edge, it is clear that the location or aligning of the plates may be effected cor-respondingly by not using one guiding tube or sleeve with two abutting pins, but two separate tubes each having one locating pin for the top plate and the bottom plate, respectively, or the abutting portions of the pins may have different diameters.
When high (wide) web strips and a great number of punching elements 85 in the jaws 76 are used, it may be rather heavy to move the shaft 81 man-ually with the handle 82. It may then be preferable to rotate the shaft 81 in some other manner, for example with a nut wrench which may be driven pneumatically or electrically. Furthermore, it is clear that the closing of the jaws can take place in various ways, for example through hydraulic cyl-inders.
With reference to Figures 8, 17, 18 and l9 there will now be de-scribed aligning means ensuring that the longitudinal strips 4 along the element edges are held in correct positions between their fixation points.
This function is performed by the side rails 120, 120' with the holders 140 and the aligning rulers 160.
The side rails 120, 120' may preferably be steel flats as shown in cross-section in Figure 18. The rail may be made in sections jointed by splice plates and screws as indicated at 121. On the bottom side of the rail are mounted ball rolls 122 suitably spaced, so as to permit the rail to move easily over the beam 31 and the bottom plate 33 of the jig. In each end the ~0394~33 rail is fixed to a bracket 123 equipped with ball bushings 124 capable ofrunning along a stationary transversal guiding rod 125 fixed in stands 126, 126' on the jig frame. This arrangement ensures that the rail 120 at its ends is fixed against rotation in the horizontal plane, a fact which consid-erably increases the bending stiffness of the rail in the horizontal direc-tion.
The two opposite side rails 120, 120' can be moved in parallel relation and synchronously towards and away from each other by means of a pair of transversal spindles 127 which are suitable journalled in the stands 126, 126' on the jig frame and which have opposi~ely threaded end portions passing through correspondingly threaded nuts 128 fixed in bearing blocks 129 on the respective brackets 123.
The two spindles 127, one on either end of the jig, are synchro-nized to a shaft 130 which extends along the jig frame and which is journal-led in suitable bearings attached to the beam 31. This shaft is connected to each of the spindles 127 through a worm 131, a worm gear 132, a short transversal shaft 133 journalled in the beam 131~ and gears 134, 135, as shown in Figure 18.
The side rails 120, 120' can be moved by turning the shaft 130 by 20 means of a motor not shown in the drawings.
In Figure 19 is seen a holder 140 for the supporting and aligning rulers 160. The holder 140 consists of a sleeve 141 through which there passes a rod 142 which by the action of a pressure spring 143 and a stopping ring 147 on the rod is ~lrged to the right in the drawing. The rod 142 slides in bearings 146 mounted in the sleeve 142. To the right end of the rod 142 there is fixed a vertical sleeve 150 which holds a fixed lower abutting pin 151 and an upper abutting pin 152 which can be pushed downwards against the action of a compression spring 153. The movement of the pin 152 is limited by a stopping peg 154 running in a slot 155 in the sleeve 150.
The abutting pins 151, 152 are formed with transversal grooves 156 receiving the rulers 160 which bear against the outside of the web strip 4 and are held in place in their respective grooves by spring-loaded locking ~Lai3~3~83 pins 157 (only shown in the upper part of Figure 19) mounted in the pins 151, 152 and having suitable semi-spherical end portions projecting into longi-tudinal grooves 161 in the rulers.
As shown, each of the abutting pins 151, 152 is formed with grooves 156 for two rulers. This is done to permit these sections of such rulers to overlap longitudinally whereby it becomes possible in a simple way to build up the desired length of lateral support.
As shown in Figure 19, the holder 140 is detachably mounted on the side rail 120 with short pins 145 which are fixed in the sleeve 141 and fit 10 into holes 139 (Figure 17) drilled at suitable intervals in the rails 120.
The arrangement shown in Figure 19 has the function to ensure that the strip 4 will remain upright at the exact desired distance from the edges of the flange plates 27 3 throughout the strip length between the clamping points. This is achieved by the abutting pins 151, 152 which are pressed against the edges of the flange plates, while the web strip 4 is pressed against the rulers 160 with a somewhat smaller outward pressure. This out-ward pressure may for example be provided by suitable insulating material such as mineral wool or similar material, placed inside the element7 as in-dicated in the figure.
It will now be explained how an element of the type shown in Fig-ure 1 is set up for pressing in the jig shown in Figure 8.
The lower plate 2 is placed on the bottom plate 33 of the jig, with one end edge abutting against the lower abutting pins of the fixed transom 40 to the right in Figure 8. The movable transom 40 is then dis-placed a certain distance inwards over the lower element plate in the direc-tion towards the fixed transom. For this to be possible, it is necessary that the units 70 on the movable transom are in their open position, so that the abutting pins 101' (Figure 14) are lifted and do not bear against the end of the lower plate 2. Thereafter the transversal web strips 5, with the folds 17' preferably already formed, but not yet completely pinched togeth-er, are placed between the jaws 76, 76' of the respective units 70, 70'.

As previously mentioned, the longitudinal strips 4, 4~ are cut ~L~39483 to a somewhat shorter length, typically about 5~ shorter, than the length of the element to be manufactured. These strips are cut along the line of symmetry in the trough-shaped depressions 17 as shown in Figure 5c. The ends of the strips 4, 4' are now placed in the respective folds in the transverse strips 5, and the units 70, 70' are closed by means of the handles 82 as ex-plained above. At the same time the deformation connections 21 are formed ; and the exterior units 70 are displaced somewhat outwards along the respec-tive transoms as a consequence of the cam element 91 pushing against the fixea element 92' (Figure 13) whereby the end strips 5 are stretched. The 10 lever 105 moves to its lower position (Figure 16) so that the abutting pins 101' are free to be pushea down towards the upper siae of the lower plate 2.
The movable transom 40 can then be moved backwaras (towards the left in Fig-ure 8) by means of the driving unit 50 until the abutting pins 101' on the same come outside the left terminal edge of the lower plate 2. If required, the transom 40 is then moved a bit forwards again in order to bring the abutting pins 101 to bear firmly against the edge of plate 2.
The longitudinal web strips 4 have now been stretched so strongly that warps and undesirable curvatures which always are present in such strips from the strip production process, have largely been eliminated, and the `;~
strips are standing as tensioned strings.
Now, the side rails 120, 120' with the holders 140 and the sup-porting rulers 160 are moved towards each other and thereby force the plate 115 with sleeve 110 to turn around the shaft 116 (Figure 13) until the stop-ping screw 118 bears against the jaw 76. During this movement, which takes place in all the four corners of the element, one or two of the lower abut-ting pins in the sleeves 110 pushes the lower plate laterally to its correct position if the plate is not already lying correctly. The plate 2 will then be locked or clamped in the desired position relatively to the corner joints 20 between longitudinal strips 4 and end strips 5.
As the side rails 120, 120' are moved towards each other, the abutting pins 151 in the holders 140 will come to bear resiliently against the longitudinal edges on the plate 2, and the rulers 160 ensure the desired -~39~3 distance between the strips 4 and the edges of the plate.
Insulating material may now be placed between the web strips. This material may preferably be mineral wool mats which are cut accurately in the direction of width so as to press the outer web strips 4 outwards towards the rulers 160. The internal longitudinal web strip 4 will be subject to approximately the same pressure on both sides and this fact together with the tension in the strip is sufficient for the strip to adjust itself to a reasonably correct position. Actually, the central strip will sometimes be standing somewhat out of plumb and also not completely straight as seen from above, but experience has shown that with the shape of the teeth and the strip profile shown in Figures 3 and 4 complete embedding of the teeth and ; an~absolutely satisfactory connection between the web strip and the flange plates are achieved.
The top plate 3 can now be put in place abutting against the re-spective pins 101, 111 and 152, and the element is ready for pressing.
With reference to Figures 20 to 24 there will now be described an embodiment of a machinery wherein the jig with the element set up therein is transported into and out from a press designed for stepwise pressing of long elements.
As shown diagra~matically in elevation in Figure 20 the jig frame 30 rests on a wheel and roller track 200. ~he side beams 31 of the jig rest on stationary wheels 201 shaped with flanges affording lateral stability of the jig frame (also shown in dash-and-dot lines in Figure 9). The bottom plate 33 of the jig rests on rollers 202. The supporting structure for the wheels and the rollers (Figure 22) includes legs 203 bolted to the floor, and transverse beams 204 which carry longitudinal beams 205, 206 on which the wheels 201 are journalled. To the upper ends of the legs 203 are welded longitudinal beams 207 with channel section, and a central longitudinal channel beam 208 is carried by short struts welded to the transverse beams ; 30 204. In the longitudinal beams 207, 208 the rollers 202 are Journalled.
A driYe chain 220 is arranged in an endless loop with its upper course in the channel beam 208 and its lower course suspended under the transverse beams 204. The chain is passed around sprocket wheels 221, 221', and 222, 222' at either end of the wheel and roller track 200. The chain is driven by a motor with a suitable brake, diagrammatically indicated at 225 in Figure 20. The arrangement shown involves that the rear end of the jig, point 226 in Figure 20, can only be moved up to the rear end of the roller track 200, approximately up to the sprocket wheel 222, so that the extreme rear portion of the jig cannot be utilized for accomodating the element.
Although this means that some space is lost, this arrangement has the advan-tage that a walking passage is obtained between the wheel and roller track 200 and the press 230, a fact which very considerably facilitates the oper-ation of the manufacturing line.
As shown in Figure 21, along the sides of the press plate 231' there are also provided stationary wheels for supporting the ~ig frame, and furthermore, on the rear side of the press, to the right in Figures 20 and 21, there is mounted a wheel and roller track 210 of a similar design as the track 200, but without the chain drive 220, so that it is possible to move the jig into and through the press as far as the length of the set up element requires, with the limitation stated above.
As shown in Figures 20 and 21 the press 230 is considerably shorter than the longest element which the ~ig 30 can accommodate. For reasons of clarity, only the press plates are shown, and it is assumed that the lower press plate is fixed while the upper press plate moves up and down. The press may be hydraulic or mechanic and may be of known design, apart from one detail which will be discussed below. It is, however, of considerable importance that the upper press plate is guided vertically, so that during the working stroke it will move in parallel relation to the lower press plate, without any horizontal displacement in the longitudinal or transversal directlon. Furthermore, it is required that the movable press plate will stop its movement when the element has been pressed to the exact desired height, regardless of the pressing force or specific pressure which might be attained. In other words, the press must be controlled by movement rather than by force. The design of a suitable press does not involve specific or 1~3~4~3 unusual problems and can be performed with well known technology.
As shown in Figure 20 and somewhat exaggerated in Figure 23, thepress plates are shaped with gently converging end portions 232 at the en-trance end. This makes it possible to press long elements in several steps.
The converging portions 232 then function to provide a smooth transition be~
tween that part of the element which in one pressing step is being pressed completely and that part of the element which is not yet pressed, so that the flange plates 2, 3 will attain a smooth and well controlled curvature which is well within that maximum deformation to which the plate material can be subjected without damage. Experiments have shown that a particle board plate is more or less sheared off if one attempts to press an element in steps with ordinary flat press plates without a transition zone as de-scribed.
In Figure 23 the transition portion 232 is shown with a gentle S-shaped curvature with horizontal end tangents. Such a curve may be expressed mathematically as a trigonometric function or as a polynomal function or may simply be designed graphically. The transition zone 232 may also be made up of a number o~ inclined surfaces or simply be one inclined plane of suffi-cient length. The main point is, as mentioned above, that a smooth transi-tion is achieved between the completely pressed and the not yet pressed part of the element with a continuously decreasing embedding of the web teeth into the flange plates 2, 3. The extremities of the transition zone should con-sequently be at levels with a difference corresponding to the penetration depth of the teeth in the respective plates, that is the length of the teeth.
Figures 2~a-d illustrates diagrammatically four situations during the pressing of a long element, corresponding to two pressing steps. For the sake of clarity, the web plates 2, 3 of the element has been shown as single lines, and difference between the levels of the extremities of the transition portion is somewhat exaggerated.
Figure 24a shows the setup element as it has been transported into the press, but before the first stage has been pressed. The plates 2, 3 and the web strips ~ are then not structurally interconnected and the individual ~39~3 components ad~ust themselves to the shape of the lower press plate. It is to be noted that the front part of the element with the front end strip 5 is lifted somewhat relative to the entrance level 240 and therefore also reia-tive to the jig frame, which in all positions lies at the same level (the top of the beam 31 is at level 240). In order to follow this lifting move-ment the bottom plate 33 of the jig is mounted vertically movable relative to the ~ig frame 31, 32 as mentioned in connection with Figure 8, and the transoms 40, to which the web strips are clamped, can also move somewhat in the vertical direction relative to the frame 31, 32 (see Figures 10 to 12).
Figure 24b shows the situation after the first part of the element has been pressed. During the pressing the bottom plate of the jig and the foremost transom 40 move down again to the normal position. After pressing, the upper press plate 231 is lifted anew, and the ~ig 30 is moved forwsrd to the position shown in Figure 24c, where the major part of the pressed element protrudes outside the press, while a smaller part Cl-C2 lies in the press in order to guide the element so that the part being pressed in the second stage will be aligned with the part already pressed, and hence the element becomes straight. As indicated in Figure 24c, one or more spring-loaded rollers 245 may be used as a temporary support for the protruding part of the element.
Figure 24d shows the situation after pressing of the second stage, that is with the press plates in the same position as in Figure 24b. The pressing o~ the remaining stages takes place in a manner sin~lar to what has been explained above.
Thus, the production of an element includes the setting up of the element in the jig as described above. The ~ig then lies on the wheel and roller track 200 as shown in Figure 20. By means of the chain drive 220 the jig is pulled into the press and stops in the position shown in Figure 24a.
The upper press plate goes down and presses the element to the desired height (thickness). The upper press plate goes up, and the jig is moved one step forward into the press, whereafter the next portion is pressed. This is re-peated until the whole element has been pressed.
Thereafter the jig is pulled back to its starting position. In 3g~a~3 order to be able to lift the element out of the jig is it necessary first to move the side rails 120, 120' away from each other. Thereafter the clamping units 70, 70' on the fixed transom 40 are opened. This is done by turning the shafts 81 in the respective units about 90 (Figure 13) so that the Jaws 76, 76' move away ~rom each other, but not so much that the eccentrics 91 attempt to mo~e the units inwards on the transoms, since the channel folds on the end strips 5 in which the longitudinal web strips 4, 4' are locked, have now been fixed to the flange plates 2, 3 and therefore prevent such movement.
Thereafter the movable transom 40 is driven backwards (to the left in Figure 8), so that the element can be pulled away from the fixed tra~som 40. ~ow the clamping units 70, 70' on the movable transom 40 are opened, and this movable transom is then driven still further backwards so that the ele-ment will lie freely on the bottom plate 33, whereafter it can be lifted out of the ~ig with a suitable hoisting device.

~L~39483 It is possible to make the stepwise movement of the jig through the press and the appurtenant activation of the press automatic, so khat no manual operation is required from the moment when the jig starts its movement towards the first pressin~ position till the moment when it returns to its starting posi~ion. This can be done with known teahnology.

Also it is obvious that it is possible to make various modifi-cations, substitutions, omissions and additions to the manufacturing machiner~ and method and the web strip described above and shown in the drawings, within the scope of the invention as defined in the appending claims.

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Claims (24)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for the manufacture of construction elements comprising two plates of nailable material and web strips holding the plates together in spaced apart relationship and consisting of elongated, sinuous sheet metal strips having along its longitudinal edges a plurality of teeth which are em-bedded in the respective plates, characterized by the use of web strips which are underdimensioned in relation to their length in the finished element, and by gripping the web strips with gripping means which are displaceable relat-ively to each other, and stretching the web strips in their respective length directions to their respective correct lengths by moving said gripping means relative to each other, whereafter the web strips and the upper and lower plates of the elements are brought into correct mutual positions and pressed together.

2. A method according to claim 1, characterized thereby that gripping and stretching of longitudinal web strips is effected by clamping means which also clamp folds of transverse web strips onto the ends of the longitudinal web strips, and which are displaced sideways for stretching these transverse web strips.

3. A method according to claim 2, characterized thereby that in connec-tion with the clamping of the folds onto the ends of the longitudinal web strips there are also punched deformations in the jointed strips for mutually locking these against vertical displacement.

4. A method according to any of the claims 1, 2 or 3, characterized thereby that for the pressing there is used a press of a working length smaller than the length of the elements to be manufactured and that after the clamping operation these elements are moved stepwise through the press for stagewise pressing, and that by each pressing operation except the last one there is pressed a portion of the element which in a longitudinal vertical plane converges as a smooth transition between that part of the element which is completely pressed and that part of the element which is not yet pressed together.

5. A method according to claim 1, characterized by that the longitud-inally underdimensioned web strips and the plates are placed in a movable clamping frame, on which the gripping means are mounted mutually displace-able and on which there are also mounted mutually displaceable locating means for the vertical alignment of the plates relative each other and to the web strips, and that after the completed gripping, stretching and locat-ing operations the frame is moved into a press for pressing of the element, whereafter the gripping and locating means are manipulated for releasing the element.

6. A method according to claim 5, characterized in that as locating means for the mutual alignment of the plates at the ends of the element there are employed abutting means which are connected to the gripping means and are displaced mutually together with the gripping means and also can move resiliently in a vertical direction, so that on stretching of the longitudin-al web strips the displaced lower end abutment means moves past the corres-ponding edge of the element bottom plate and snaps down, and that in the press all the said abutting means are pushed in vertically by the press plates.

7. A method according to claim 5, characterized thereby that the web strips along the side edges of the element are supported between the respect-ive clamping points against outward transverse displacement by longitudinal rulers placed on the outside of the web strips while these web strips are supported on their inside by material placed within the element.

8. A method according to claim 7, characterized in that the rulers are brought into correct position relative to the plates by being spring-loaded inwards towards the respective web strips and are connected to abutting means which engage the side edges of the plates and are retractable in the vertical direction.

9. Machinery for carrying out the method of claim 1 comprising means for assembling the plates and web strips, a press for pressing the resulting assembly together, and means for conveying the assembly into and out of the press, wherein said assembling means includes means to grip the end portions of the web strips, said gripping means being mounted on a supporting structure and displaceable relative to each other, said gripping means in use being moved relative to each other in the respective length directions of the web strips, thereby stretching these web strips to their desired lengths, said gripping means also holding the web strips in a stretched condition during the pressing operation, and locating means for mutual vertical alignment of the element plates and stretched web strips.

10. Machinery according to claim 9, characterized in that the locating means for the mutual alignment include mutually displaceable abutting means adapted to engage the lateral edges of the plates and to be moved in a ver-tical direction against the action of springs so as to follow the pressing movement.

11. Machinery according to claim 9, characterized by including longitu-dinal rulers which can be made to bear against the external face of the web strips running along the longitudinal side edges of the element between the clamping points of these web strips, thereby supporting said web strips ex-ternally against lateral displacement, while said strips on their inside are supported by material placed inside the element.

12. Machinery according to claim 11, characterized in that the rulers are spring-loaded inwards and connected to vertically movable abutting means which can be caused to bear against the side edges of the plates.

13. Machinery according to claim 9, characterized in that the locating means for the mutual alignment of the plates are displaceable relative to each other together with the gripping means and also are vertically movable relative to the gripping means thereby being able to follow the pressing movement.

14. Machinery according to claim 13, characterized in that the lower end abutting means which are being displaced during the stretching of the longitudinal web strips, are arranged so that in a starting position of the clamping means said lower abutting means are held in a lifted position and thereafter released so that during the stretching operation they snap down resiliently outside the respective plate edge.

15. Machinery according to claim 9 characterized in that the supporting structure includes a rigid clamping frame arranged to be transported into and out of the press for the pressing of elements.

16. Machinery according to claim 15, characterized in that the locating means for the mutual alignment include mutually displaceable abutting means adapted to engage the lateral edges of the plates and to be moved in a verti-cal direction against the action of spring so as to follow the pressing move-ment.

17. Machinery according to claim 16, characterized in that the clamping frame is supported on its way through the press by transport tracks outside the side edges of the press plate and is provided with a liftable bottom on which the lower plate of the element rests and against which the lower abut-ting means bear, and which bottom plate is capable of sliding onto and off from the lower press plate.

18. Machinery according to claim 9, characterized in that the gripping means are arranged on two transoms and can be moved relatively to each other along these transoms for the stretching of transverse web strips at the ends of the element, that at least one transom is movable in a direction away from the other for the stretching of longitudinal web strips, and that the opera-tion of the gripping means for the clamping of the web strips and for displace-ment along the transoms prior to the stretching of the longitudinal web strips is so interlinked that during the clamping operation these means will first cause stretching and thereafter clamping.

19. Machinery according to claim 14, characterized in that the gripping means are arranged on two transoms and can be moved relatively to each other along these transoms for the stretching of transverse web strips at the ends of the element, that at least one transom is movable in a direction away from the other for the stretching of longitudinal web strips, and that the oper-ation of the gripping means for the clamping of the web strips and for dis-placement along the transoms prior to the stretching of the longitudinal web strips is so interlinked that during the clamping operation these means will first cause stretching and thereafter clamping.

20. Machinery according to claim 19, characterized in that the operat-ion of the displaceable gripping means on the movable transom is also inter-linked with an operation of the lower end abutting means connected thereto so that these in a starting position are kept lifted and thereafter are released before stretching and clamping have been completed.

21. Machinery according to claim 9, characterized in that the gripping means are adapted to be opened sufficiently to grip the outside of folds formed in the web strips and thereafter to pinch the folds together and onto the end portions of adjoining web strips meeting at right angles.

22. Machinery according to claim 17, characterized in that the gripping surfaces of the gripping means are shaped with cooperating punch- and die elements for the formation of deformation locks in the folds and the adjoin-ing web strips pinched in the folds.

23. Machinery according to claim 9, characterized in that the gripping and locating means are adapted for clamping of elements of greater length than the working length of the press, and that the working surfaces of the press plates at their entrance end converges vertically to a degree sufficient for providing a smooth transition from a completely pressed part of the ele-ment to another part of the element which is not yet pressed.

24. Machinery according to claim 23, characterized in that the con-verging portions have a gentle S-shaped curvature with horizontal tangents at the ends and with a level difference between the end points which corres-ponds to the penetration depth of the web strips.