GB1573849A

GB1573849A - Method and device for bending corrugated sheet and a bent corrugated sheet

Info

Publication number: GB1573849A
Application number: GB2517677A
Authority: GB
Original assignee: KORSTRAESK MEK G NAESLUND
Current assignee: KORSTRAESK MEK G NAESLUND
Priority date: 1977-06-16
Filing date: 1977-06-16
Publication date: 1980-08-28

Description

(54) METHOD AND DEVICE FOR BENDING CORRUGATED SHEET AND A BENT CORRUGATED SHEET (71) We, KORSTRSK MEKA NISKA, G. NASLUND, a Swedish Company, of P1. 687, S-942 00 Alvsbyn, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method and a device for bending corrugated sheet, as well as to a bent corrugated sheet. The sheet may be a corrugated plate, strip or similar object of metal or other material, and the corrugations may be of trapezoidal cross-section.

In the following description and in the claims the corrugations will for convenience be considered as comprising alternating crests and valleys having common side walls. It should be understood that this definition depends on the sheet being viewed at all times from one side and that, if the sheet is viewed from the other side, the crests will become valleys and the valleys will become crests. The corrugations may be of any cross-section even if this means that the boundaries between the side walls and the crests and valleys are not clearly defined.

It is already known to bend corrugated sheets perpendicularly to the longitudinal direction of the corrugations by rolling the sheets. It has proved very difficult, however, to roll-bend sheets with a section of relatively great depth so as to obtain thereby a satisfactory shape of the bend proper and so as to prevent weakening of the material in the vicinity of the bend.

An object of the present invention is to provide a method of bending corrugated sheets transversely of the longitudinal direction of the corrugations, which method overcomes or reduces substantially the aforesaid disadvantages and renders it possible even to bend sheets with a section of relatively great depth to a desired angle. The invention further has the object of producing a simple and serviceable device for bending corrugated sheets.

According to the invention, there is provided a method of bending a corrugated sheet the corrugations of which form alternating crests and valleys having common side walls when viewed from one side of the sheet, which method comprises forming at least one straight line of indentations in the sheet transversely of the corrugations, the indentations being impressed from the opposite side of the sheet so as to form in the valleys ridges which meet the side walls substantially at the level of the tops of the ridges, thereby causing the sheet to bend transversely of the corrugations.

The invention also provides a device for bending a corrugated sheet the corrugations of which form alternating crests and valleys having common side walls when viewed from one side of the sheet, which device comprises an assembly formed by a strip having an edge for fonning indentations in the sheet and a sheet holding member intended to be disposed on the opposite side of the sheet to the strip during bending and comprising two bars of substantially the same length as the edge, the bars being spaced apart so that the sheet holding member straddles the strip with the bars on opposite sides of the plane within which the strip is disposed, and means for moving the strip and the sheet holding member towards and away from each other so as to enable indentations forming ridges in the valleys to be impressed in the sheet by the strip, the ridges meeting the side walls substantially at the level of the tops of the ridges, thereby causing the sheet to bend transversely of the corrugations.

The invention further provides a corrugated sheet the corrugations of which form alternating crests and valleys having common side walls when viewed from one side of the sheet, which sheet has been bent transversely of the corrugations by being provided on the opposite side with at least one straight line of indentations transversely of the corrugations forming in the valleys ridges which meet the side walls substantially at the level of the tops of the ridges.

The invention is described in greater detail in the following with reference to the accompanying drawings, in which: Fig. 1 is an end view of a bending device according to the invention; Fig. 2 is a lateral view of the same, partially in section, with a sheet inserted to be bent; Fig. 3 is a schematic lateral view of a sheet bent in the bending device according to a method of the invention; Fig. 4 is a section along the line IV-IV in Fig. 3; and Figs. 5 and 6 are perspective views of a 900bend produced by a method according to the invention.

The embodiment of the device according to the invention shown by way of example in the drawings is intended to be used particularly for bending trapezoidal cross-section corru gated sheets, for example of the type shown in Fig. 4 perpendicularly to the longitudinal direction of the corrugations. The device is designed so as to be capable of bending the sheet in two places simultaneously. The invention, of course, is not restricted to the type of sheet shown by way of example, but can be applied to the bending of many other types of corrugated sheet.

The illustrated embodiment of the device according to the invention comprises a table 1 which movably supports two carriages 2 which, by means of a screw mechanism 4 with a hand wheel 3 for each carriage, can be set in different positions relative to each other and the table. Each carriage is provided with a press head 5 which is supported pivotally on a shaft 7 mounted in bearings 6 on the carriage 2 so as to be capable of being adjusted step-by-step to different angular positions in relation to the plane of the table from a substantially vertical position to a substantially horizontal position as indicated by dashed lines in Fig. 2. The step-by-step adjustment of the press head 5 can be effected by a con trol device, for example in the form of a hydraulic cylinder 8 which is disposed between the carriage 2 and a locking disc 9 connected to the shaft 7 or press head 5. The locking disc 9 is provided with locking teeth 10 at least along a part of its periphery, which teeth cooperate with a pawl 12 controlled by a control device 11, for example in the form of a hydraulic cylinder, for locking the press head in different angular positions. The locking disc 9 in the embodiment shown is provided with six locking teeth 10, and the angle between adjacent locking teeth is 15". This enables adjustment of the press head to six different positions with an angular difference of 150 between each of the adjacent positions. In other embodiments, of course, the locking disc may have a different number of teeth and the angle between the teeth may be either greater or smaller, according to the number of adjusting positions desired for the press head 5.

Each press head comprises a sheet holding member 13 and beneath the same a press beam 14, both of which are vertically movable in the press head. The press beam is guided with its ends between guide means 16 located on the end walls 15 of the press head and is supported on two piston-cylinder arrangements 17 disposed in the press head, by means of which the press beam 14 can be lifted and lowered. The press beam 14, on its side facing towards the sheet holding member 13, is provided with a press tool in the form of a thin rounded press strip 18 extending along the greater part of the press beam length, which corresponds at least to the width of the sheet to be bent.

The sheet holding member 13, like the press beam 14, is guided at its ends between the guide means 16, and is suspended in the press head by two toggle levers 19 which are interconnected by a control device 20 shown in the form of a piston-cylinder arrangement, by which the sheet holding member 13 can be lifted and lowered to the extent permitted by the toggle levers 19. In order to prevent lateral movement of the sheet holding member 13 in the press head 5, the member 13 is provided with a guide member 21, for example a guide wheel, disposed without clearance in a guide slot 22 of a plate 23 attached to the press head. The control device 20 for the toggle levers 19 is also guided in the guide slot 22 by means of a fixing member 24, preferably in the form of a wheel permitting movement of the control device 20 in the vertical direction.

The sheet holding member 13 comprises a beam 25 which on its side facing towards the press beam 14 is formed with a distance member 26 which is located directly opposite the press strip 18 and on each side exchangeably carries a respective holding bar 27 of substantially the length of the press strip with a contour substantially corresponding to the transverse profile of the sheet to be bent. The holding bars 27 extend beyond the distance member 26 towards the press beam by a distance corresponding substantially to the height of the press strip 18 on the press beam 14. The holding bars are spaced apart a distance substantially corresponding to the thickness of the press strip 18 plus twice the thickness of the sheet.

When the press heads have been set in a substantially vertical position as shown in solid lines in Fig. 2, a sheet to be bent can be introduced between the press beam 14 and the sheet holding member 13 in the two press heads 5. If the press heads are not in the position shown in solid lines in Fig. 2, they are set in this position by the control device 8 and locked therein by the pawl 12. In this position, the sheet holding member 13 is lowered by the control device 20 and locked in this position by the toggle levers 19. Projections 28 (Figure 1) of the holding-bars engage thereby with the so-called valleys in the sheet, which projections have a width corresponding to the width of the valleys at their bottom. When the sheet holding member has been locked in its lowered position, the hydraulic cylinders 17 of the press beam are actuated to lift the latter and thereby impress indentations 31 in the sheet from below between the two holding bars 27 over the entire width of each valley, whereby indentations 29 are formed in the upwardly facing side walls 30 of the valleys, as shown in Figs. 3 and 4, without subjecting the sheet to detrimental stretching or drawing. In order to prevent drawing of the sheet especially in the case of two simultaneously operating press heads, at the beginning of the impressing operation each press head 5 can be disengaged from locking by the pawl 12 and the control means 8, so that the head is " floating" in relation to the carriage and is held exclusively by the engagement of the press beam and sheet holding member with the sheet. As soon as this engagement ceases after an impression has been made, the press head is again locked in the position intended. By such an impression the sheet is bent one step which in the embodiment shown corresponds to an angle of about 15 . Thereafter both the press beam 14 and the sheet holding member 13 are returned to their respective rest positions, and the two press heads 5 are turned through one step in opposed directions, which step in the embodiment shown corresponds to an angle of 150.

Thereafter the sheet holding member 13 is again lowered and locked in the lowered position, and the press beam 12 is lifted to effect a new impression in the sheet, whereby the sheet is bent a further step corresponding to an angle of approximately 15 . This procedure is repeated until the sheet has been bent to the desired angle, which in the present embodiment is 90 , the two press heads 5 finally assuming the position indicated by dashed lines in Fig. 2 so that the bent sheet can be easily removed by being lifted straight upward.

In Figs. 5 and 6, a 900 bend obtained according to the invention in a sheet having trapezoidal cross-section corrugations, as illustrated in Fig. 4, is shown from above and below respectively. The bend has been formed by impressing on the lower surface of the sheet six sets of indentations 31 of substantially arcshaped cross-section in the valleys 32 of the sheet, which indentations form straight ridges 33 of substantially constant height in the valleys, as shown in Fig. 5. The bottom of each ridge has a length corresponding to the width of the valley bottom and the top 34 of each ridge has a length exceeding the last-mentioned width. Each ridge has a straight top and templates at the adjacent side walls substantially at the level of the top of the ridge.

Furthermore the top of the ridge extends into the indentations 29 in the side walls 30 of the valley in question, which indentations are formed automatically when the indentations 31 are being made and extend taperingly up to the junctions 35 between the side walls and the tops of the adjacent crests. The indentations 29 are matched by bulges 36 on the other side of the side walls 30 designated by 37 in Fig. 6. The number of sets of indentations 31 can be chosen to vary from one case to another and need not be six as in the embodiment shown.

The present invention is not restricted to the embodiment described above and shown in the drawings, but can be modified and altered in many different ways. The device according to the invention, for example, can be provided with only one press head, and its stepping can be effected in steps corresponding to an angle greater or smaller than the one mentioned above. It is also possible to dispense with the pawl with associated details and instead to effect the necessary stepping of the press head or heads by cam-controlled electric valves (one cam for each desired position), which valves control the control device 8. The positions of the press tool and sheet holding member may also be exchanged, so that the press tool is positioned above the sheet holding member in the press head.

WHAT WE CLAIM IS: 1. A method of bending a corrugated sheet the corrugations of which form alternating crests and valleys having common side walls when viewed from one side of the sheet, which method comprises forming at least one straight line of indentations in the sheet transversely of the corrugations, the indentations being impressed from the opposite side of the sheet so.

as to form in the valleys ridges which meet the side walls substantially at the level of the tops of the ridges, thereby causing the sheet to bend transversely of the corrugations.

2. A method according to claim 1, wherein, during formation of the ridges, lateral indentations are formed in the side walls where the ridges meet the side walls.

3. A method according to claim 2, wherein the crests and valleys have tops and bottoms respectively formed by fiat mutually parallel walls and the side walls are flat and angle downwardly from said tops to said bottoms with each side wall of each valley parallel to the corresponding side wall of the next valley throughout the corrugations, so that the cor rugated sheet is of trapezoidal cross-section, and, during forming of the ridges, said lateral indentations are automatically formed in the side walls, which lateral indentations extend taperingly upwardly substantially to the junc

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Claims

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engage thereby with the so-called valleys in the sheet, which projections have a width corresponding to the width of the valleys at their bottom. When the sheet holding member has been locked in its lowered position, the hydraulic cylinders 17 of the press beam are actuated to lift the latter and thereby impress indentations 31 in the sheet from below between the two holding bars 27 over the entire width of each valley, whereby indentations 29 are formed in the upwardly facing side walls

30 of the valleys, as shown in Figs. 3 and 4, without subjecting the sheet to detrimental stretching or drawing. In order to prevent drawing of the sheet especially in the case of two simultaneously operating press heads, at the beginning of the impressing operation each press head 5 can be disengaged from locking by the pawl 12 and the control means 8, so that the head is " floating" in relation to the carriage and is held exclusively by the engagement of the press beam and sheet holding member with the sheet. As soon as this engagement ceases after an impression has been made, the press head is again locked in the position intended. By such an impression the sheet is bent one step which in the embodiment shown corresponds to an angle of about 15 . Thereafter both the press beam 14 and the sheet holding member 13 are returned to their respective rest positions, and the two press heads 5 are turned through one step in opposed directions, which step in the embodiment shown corresponds to an angle of 150.

Thereafter the sheet holding member 13 is again lowered and locked in the lowered position, and the press beam 12 is lifted to effect a new impression in the sheet, whereby the sheet is bent a further step corresponding to an angle of approximately 15 . This procedure is repeated until the sheet has been bent to the desired angle, which in the present embodiment is 90 , the two press heads 5 finally assuming the position indicated by dashed lines in Fig. 2 so that the bent sheet can be easily removed by being lifted straight upward.

In Figs. 5 and 6, a 900 bend obtained according to the invention in a sheet having trapezoidal cross-section corrugations, as illustrated in Fig. 4, is shown from above and below respectively. The bend has been formed by impressing on the lower surface of the sheet six sets of indentations 31 of substantially arcshaped cross-section in the valleys 32 of the sheet, which indentations form straight ridges 33 of substantially constant height in the valleys, as shown in Fig. 5. The bottom of each ridge has a length corresponding to the width of the valley bottom and the top 34 of each ridge has a length exceeding the last-mentioned width. Each ridge has a straight top and templates at the adjacent side walls substantially at the level of the top of the ridge.

Furthermore the top of the ridge extends into the indentations 29 in the side walls 30 of the valley in question, which indentations are formed automatically when the indentations 31 are being made and extend taperingly up to the junctions 35 between the side walls and the tops of the adjacent crests. The indentations 29 are matched by bulges 36 on the other side of the side walls 30 designated by 37 in Fig. 6. The number of sets of indentations 31 can be chosen to vary from one case to another and need not be six as in the embodiment shown.

The present invention is not restricted to the embodiment described above and shown in the drawings, but can be modified and altered in many different ways. The device according to the invention, for example, can be provided with only one press head, and its stepping can be effected in steps corresponding to an angle greater or smaller than the one mentioned above. It is also possible to dispense with the pawl with associated details and instead to effect the necessary stepping of the press head or heads by cam-controlled electric valves (one cam for each desired position), which valves control the control device 8. The positions of the press tool and sheet holding member may also be exchanged, so that the press tool is positioned above the sheet holding member in the press head.

WHAT WE CLAIM IS: 1. A method of bending a corrugated sheet the corrugations of which form alternating crests and valleys having common side walls when viewed from one side of the sheet, which method comprises forming at least one straight line of indentations in the sheet transversely of the corrugations, the indentations being impressed from the opposite side of the sheet so.

as to form in the valleys ridges which meet the side walls substantially at the level of the tops of the ridges, thereby causing the sheet to bend transversely of the corrugations.
2. A method according to claim 1, wherein, during formation of the ridges, lateral indentations are formed in the side walls where the ridges meet the side walls.
3. A method according to claim 2, wherein the crests and valleys have tops and bottoms respectively formed by fiat mutually parallel walls and the side walls are flat and angle downwardly from said tops to said bottoms with each side wall of each valley parallel to the corresponding side wall of the next valley throughout the corrugations, so that the cor rugated sheet is of trapezoidal cross-section, and, during forming of the ridges, said lateral indentations are automatically formed in the side walls, which lateral indentations extend taperingly upwardly substantially to the junc

tions between the side walls and the tops of the adjacent crests.
4. A method according to any preceding claim, wherein each ridge is rounded transversely of its length.
5. A method according to any preceding claim, wherein, to form the ridges, an edge of a straight strip is pressed upwardly from the opposite side of the sheet simultaneously into the bottoms of all the valleys whilst holding down the sheet along hold-down lines extending transversely of the corrugations above the sheet and spaced apart longitudinally with respect to the corrugations so that the ridges are formed between the hold-down lines.
6. A method according to claim 5, wherein the hold-down lines are spaced apart a distance substantially equal to the thickness of the strip plus twice the thickness of the sheet.
7. A method according to any preceding claim, wherein, in order to bend the sheet about a horizontal axis, the sheet is placed above that axis and indentations are impressed from below along a first straight line substantially parallel to the axis whilst holding down the sheet along spaced hold-down lines utilising hold-down means above the sheet, and subsequently further indentations are impressed from below along a second straight line substantially parallel to the axis.
8. A method according to claim 7, wherein the hold-down means is turned about the axis through a predetermined angle which is a submultiple of the desired bending angle intermediate the two impressing steps.
9. A device for bending a corrugated sheet the corrugations of which form alternating crests and valleys having common side walls when viewed from one side of the sheet, which device comprises an assembly formed by a strip having an edge for forming indentations in the sheet and a sheet holding member intended to be disposed on the opposite side of the sheet from the strip during bending and comprising two bars of substantially the same length as the edge, the bars being spaced apart so that the sheet holding member straddles the strip with the bars on opposite sides of the plane within which the strip is disposed, and means for moving the strip and the sheet holding member towards and away from each other so as to enable indentations forming ridges in the valleys to be impressed in the sheet by the strip, the ridges meeting the side walls substantially at the level of the tops of the ridges, thereby causing the sheet to bend transversely of the corrugations.
10. A device according to claim 9, wherein, during formation of the ridges, lateral indentations are formed in the side walls where the ridges meet the side walls.
11. A device according to claim 9 or 10, wherein the edge of the strip is transversely rounded.
12. A device according to claim 9, 10 or 11, further comprising a frame in which the strip and the sheet holding member are mounted for reciprocation relative to each other.
13. A device according to any one of claims

9 to 12, which includes two of said assemblies which are positioned to simultaneously receive spaced-apart portions of the sheet to be bent, the assemblies being mounted in respective frames pivotally mounted to swing generally in the longitudinal direction of the sheet.
14. A device according to claim 13, wherein means are provided for releasably locking the frames against swinging at any one of a plurality of angles.
15. A corrugated sheet the corrugations of which form alternating crests and valleys hav ing common side walls when viewed from one side of the sheet, which sheet has been bent transversely of the corrugations by being pro vided on the opposite side with at least one straight line of indentations transversely of the corrugations forming in the valleys ridges which meet the side walls substantially at the level of the tops of the ridges.
16. A corrugated sheet according to claim 15, wherein, during formation of the ridges, lateral indentations have been formed in the side walls where the ridges meet the side walls.
17. A corrugated sheet according to claim 16, wherein the crests and the valleys have tops and bottoms respectively formed by flat mutually parallel walls and the side walls are flat and angle downwardly from said tops to said bottoms with each side wall of each valley parallel to the corresponding side wall of the next valley throughout the corrugations, so that the sheet is of trapezoidal cross-section and said lateral indentations are formed in the side walls in the vicinity of the ends of the ridges, which lateral indentations extend taperingly upwardly substantially to the junctions between the side walls and the tops of adjacent crests.
18. A corrugated sheet according to claim 15, 16 or 17, wherein each ridge is rounded transversely of its length.
19. A method of bending a corrugated sheet, which method is substantially as herein before described with reference to the accom panying drawings.
20. A device for bending a corrugated sheet, which device is substantially as herein before described with reference to the accom panying drawings.
21. A bent corrugated sheet substantially as hereinbefore described with reference to Figures 3 to 6 of the accompanying drawings.