Roll Forming Of Sheet Metal

Abstract

Method and apparatus for forming sheet metal to a desired profile in draw forming rolls in which in a first roll stand an easily drawn curved initial rib is produced and in a second roll stand the rib is reshaped, for example into a pair of ribs. The method is repeated to one or both sides of the initial deformation to make further profiles, at least one further initial rib being formed in the second roll stand to one side of the first initial rib.

Description

This invention relates to a machine and a method for shaping sheet metal especially by cold draw roll forming and more particularly for forming and reshaping ribs in sheet metal.

In U.K. Pat. No. 950,059 there is described and claimed a method of forming a deep rib in a metal sheet, by means of co-operating rib-forming rolls, said method comprising deforming to a valley cross-section a longitudinal portion of a sheet having a width substantially greater than the width of the strip of the sheet from which the rib is to be formed and having as its apex the said strip from which the rib is to be formed, and acting on the said strip with one pair of co-operating rib-forming rolls to form a deep rib at a single pass through the said one pair of rolls.

There is also described and claimed in the said patent a machine for the continuous formation of a longitudinal rib in a metal sheet by the action of rib-forming rolls (the width of the sheet being substantially greater than the strip from which the rib is to be formed) said machine having means for supporting the sheet, before entry into the rolls, at a level substantially lower than the nip of the rolls so that, as the sheet approaches the rolls it is gradually transformed into a shape having a valley cross-section, the apex of the said valley section providing the strip from which the deep rib is formed as it passes through the rolls, means being provided, after the rib-forming rolls, to cause the valley section (save for the rib) to recover to the flat plane of the finished profile.

According to the present invention there is provided a method of shaping sheet meal in a single pass through a plurality of roll stands each having cooperating forming rolls to form a plurality of longitudinally extending profiles spaced laterally across the sheet each profile being formed by the reshaping in at least one roll stand of an initial rib wherein a first initial rib is formed in a first roll stand,

THE SAID FIRST INITIAL RIB IS REFORMED IN A SECOND ROLL STAND IN WHICH AT LEAST ONE FURTHER INITIAL RIB IS FORMED LATERALLY OF THE SAID FIRST INITIAL RIB,

EACH OF THE SAID INITIAL RIBS CONTAINING SUFFICIENT METAL THAT THE PROFILE WHICH IS TO BE FORMED SUBSEQUENTLY FROM IT CAN BE FORMED WITHOUT FURTHER DRAWING IN OF METAL FROM THE REST OF THE SHEET,

AS THE SHEET APPROACHES EACH RESPECTIVELY OF THE SAID FIRST AND SECOND ROLL STANDS, A PORTION OF THE SHEET BEING TRANSFORMED INTO A VALLEY CROSS-SECTION, THE APEX PORTION OF WHICH PROVIDES THE STRIP OF SHEET FROM WHICH THE RESPECTIVE INITIAL RIB IS FORMED AS THE SHEET PASSES THROUGH THE ROLL STAND.

In the second roll stand, a further initial rib may be formed to each side of the first initial rib while the latter is reshaped. Preferably the initial ribs have an arcuate cross-section and are bounded by longitudinally extending parallel bend-lines.

The present invention also provides a machine for the draw roll forming of a plurality of longitudinally extending profiles in a metal sheet passed continuously through the machine including

a first roll stand having cooperating male and female forming rolls,

a second roll stand having cooperating male and female forming rolls,

the said male forming rolls of the first roll stand having a radially projecting part which cooperates with a radially recessed part in the female roll of the first roll stand to form an initial rib in the sheet as it passes through the first roll stand,

the said male-forming roll of the second roll stand having at least one radially projecting part which cooperates with a radially recessed part of the female roll of the second roll stand to form a further initial rib in the sheet as it passes through the second roll stand, the further initial rib being spaced laterally from the said first initial rib,

the said rolls of the second roll stand having cooperating parts which reform the said initial rib formed by the first roll stand without drawing in further metal from the rest of the sheet,

there being an axially extending coaxial support flange adjacent each side of each said radially projecting part, the diameter of at least one of the support flanges adjacent each said radially projecting part decreasing with distance from the said radially projecting part, the radially projecting part and the support flanges of the male roll and the radially recessed part on the female roll assisting in the transformation of the sheet as it approaches the roll stand into a valley cross-section having an apex portion which provides the strip of sheet from which the initial rib is formed as it passes through the roll stand.

Each initial rib formed in the metal may be re-shaped to the desired profile above, below or partly above and partly below the plane of the sheet within the confines of the material between bend lines at the edges of the initial rib.

The invention further includes draw forming rolls suitable for performing the above method.

Various forms of the invention will now be described with reference to the accompanying drawings wherein:

FIG. 1 shows in perspective view a first initial rib being draw roll formed in a sheet by a first pair of rolls;

FIG. 2 shows a cross-section view of the rolls of FIG. 1 with the formed metal sheet interposed therebetween;

FIG. 3 shows in perspective view the sheet formed in the first rolls being re-shaped in a second pair of rolls part of the rolls only being shown;

FIG. 4 shows a cross-section view of the part of the rolls shown in FIG. 3 with the re-shaped metal interposed therebetween;

FIG. 5 shows a cross-section view of a reshaped portion of the sheet after passage through the rolls of FIG. 3;

FIG. 6 shows the final cross-section of the sheet shown in FIG. 5;

FIG. 7 shows further parts of the rolls shown in FIG. 3, which parts form the two initial ribs shown at the sides of the cross-section in FIG. 5; and

FIG. 8 shows the cross-section of another profile re-shaped from the initial rib shown in FIG. 2.

FIGS. 1 to 4 and 7 of the drawings show pairs of co-operating forming rolls for carrying out the method of the invention mounted on suitable shafts as provided in two consecutive roll stands (not shown for clarity) of a cold roll forming machine of known construction comprising a number of roll stands in spaced tandem relationship, the rolls being suitably powered to progressively roll form continuous metal strip to a desired profiled section. In conventional machines a considerable number of stands with the appropriate forming rolls are required for this purpose because the metal strip is progressively formed from the strip in a flat condition the successive rolls only gradually shaping the metal by pressure-forming within the dimensional limits of the desired section. The draw roll forming process as described in our U.K. Pat. No. 950,059 (and in U.S. Pat. No. 3,184,942) is a different method of forming in which the metal strip, prior to and during its passage through the machine is temporarily deformed to intermediate transitory shapes occupying a space considerably outside the dimensional limits of the finished section. The process reduces the number of roll stands and rolls and the present invention also decreases these, the method involving additional shaping in the draw roll forming rolls.

FIG. 1 shows a first pair of co-operating forming rolls in a first stand and in FIGS. 3, 4 and 7 are shown constituent parts of a second pair of co-operating forming rolls mounted at a suitable distance in the machine behind the first pair of rolls. A further roll stand is provided behind the second stand at a suitable distance as subsequently explained, the machine thus comprising three powered roll stands with the appropriate forming rolls. The section which is formed from continuous metal sheet is shown in FIG. 6 and comprises a roofing sheet 18 having six ribs of trapezoidal section. It will be noted by those skilled in the art that this example of the draw roll forming process only requires three pairs of rolls and roll stands to roll form the desired profile instead of at least twelve pairs of rolls and roll stands which would be required in the case of the conventional machines.

In FIGS. 1 and 2 a continuous metal sheet 18 is uncoiled preferably from an uncoiler (not shown) and is drawn through a male roll 10 and a female roll 12 mounted on shafts 40, 42 in a first roll stand. Male roll 10 which acts as a plunger roll has a pair of support flanges 14 flanking a central plunger part 28. The flanges 14 are disposed at an angle to each other and the two rolls in combination form in the strip 18 a curved transient valley section 32 having walls 16. The angle between the walls 16 is equal to the angle between the flanges 14.

Female roll 12 may have a pair of support flanges 20 disposed at a complementary angle to flanges 14 so that the surfaces of flanges 14, 20 where they co-operate are parallel to each other. Alternatively the female roll 12 may have a pair of disc flanges 22 as denoted by dotted lines 24 in FIG. 2. The female roll acts as a die roll having an annular recess 30 between the flanges 20 or 22. The parts of the rollers disposed between the flanges 14 and 20 respectively i.e, the plunger part 28 and the recess 30 are intended to form an initial curved rib 26 in the sheet 18 and hence will be called shaping parts. The initial rib is formed in a strip of the sheet at the apex of the valley section 32, this strip being narrower than the material in the valley section as a whole. It will be appreciated that the cross-section of the shaping parts and the angles and position of the supporting flanges are such that the two rollers mate to maintain valley section 32 in the sheet as the sheet passes through the rolls. The edge portions 34 of the valley section 32 are temporarily deformed downwardly out of the flat plane of the sheet during the passage of the sheet through the rolls, the edge portions in the process becoming sufficiently semi-resilient to allow the metal sheet to be freely drawn laterally through the rolls to form the curved rib 26.

The forming rolls 10 and 12 form the easily shaped curved rib cross-section 26 in the sheet 18. As they leave the rolls 10, 12 the walls 16 of the sheet 18 gradually recover to the flat plane of the sheet to become flat walls 36. It will be understood that the valley section 32 provides a transitory free drawing shape which is considerably deeper than the depth of the cross-section of the rib 26 and flat walls of the sheet.

Parallel bend lines 38 define the area in which the curved rib 26 has been shaped between the flat walls 36 of sheet 18. The object of the first rolls is to draw form a shape most suitable for providing the required material in a middle portion of a sheet and this is next re-shaped between the bend lines to the desired final profile without causing any distortion in the remaining portions 36 of the sheet.

In FIGS. 3, 4 and 7 4 are shown two pairs of rib-forming rolls having shafts 52,54 carrying male roll 44 parts and 46 and female roll parts 48 and 50 for re-shaping curved rib 26 into the desired profile within bend lines 38. The shafts 52,54 also carry roll parts to each side of the parts 44, 46, 48, 50 as will be described below. In this example the roll parts 44, 46, 48, 50 are provided with trapezoidal shaping parts. The rolls are mounted in a second stand of the machine situated behind the first roll stand (not shown for clarity). Male roll parts 44,46 and female roll parts 48,50 are mounted on shafts 52 and 54 and are made to match together with a suitable clearance to allow sheet 18 to pass between them and to form trapezoidal ribs 56 and 58 (See also FIG. 5).

Referring to FIG. 5 further curved initial ribs 60, 62 are formed in the second roll stand, one on each side of the portion of the sheet which has already been shaped. Alternatively, a single curved rib to one side only could be made. The ribs 60, 62 are to enable the formation of further desired profiles e.g., the two lateral pairs of ribs 64, 66 and 68, 70 shown in FIG. 6.

Suitable apparatus for forming the further initial ribs 60, 62 is shown in FIG. 7 which illustrates the sheet 18 passing between roll parts 90, 92 in a roll stand. The roll parts 90, 92 are mounted on shafts 52, 54 of the second roll stand so that the male roll parts 90a, 90b lie one on each side of male roll parts 46, 44 respectively and the female roll parts 92a, 92b one on each side of the female roll parts 50, 48 respectively.

Each pair of co-operating male and female roll parts 90a, 92a and 90b, 92b is generally similar to the rolls in FIG. 2 having similar shaping parts 94, 96 and similar support flanges 98, 100 on the side of the rolls away from the initial rib 26 which is being re-formed in the roll parts 44, 46; 48, 50. The support flange 98 on the male roll has a diameter which decreases with distance from the mid plane of the roll and the corresponding flange 100 on the female roll is either parallel to it at the nip or is cylindrical as indicated by the dotted line 102. The coaxial support flanges 104, 106 on the side towards the portion of the sheet which has already been shaped, are preferably both cylindrical as indicated so that the nip between them is parallel to the roll axles (preferably horizontal) and the part of the sheet indicated at 108 which is between the portion which has already been shaped and the further initial rib being formed has a similar disposition. A valley cross section is formed in advance of each of the roll parts 90a, 92a and 90b, 92b. As the valley passes through the rolls, it will be seen to be curved in the center and to have one horizontal wall 108 and one downwardly deflected wall 110. Material required for the valley formation may be freely drawn inwardly from the edge of the sheet. A strip of the sheet at the apex of the valley section and narrower than the width of the valley section is formed into the initial rib 62 or 60.

It will be apparent that when only one further initial rib is to be formed, only one pair of roll parts 90a, 92a or 90b, 92b is needed.

Curved ribs 60, 62 are re-shaped in a subsequent stand comprising two sets of roll parts each of which is similar to roll parts 44, 46 and 48, 50. By such means the desired final profile in FIG. 6 is achieved comprising the six trapezoidal ribs indicated in sheet 18 by using only three stands in the machine.

Where deep ribs are required, the initial ribs can be re-formed in two stages. For example, a first stand can make a first initial rib as indicated in FIG. 1 and rolls in a second stand can partly re-form the initial rib and can make further initial ribs on either side. A third stand having rolls similar to the rolls in FIG. 3 can complete the re-forming of the first initial rib and can contain rolls to begin re-forming the new initial ribs formed in stand 2. A fourth stand can complete the reforming of the new initial ribs to the desired profile.

Further stands can be provided to make more ribs if desired.

The machine illustrated is adapted for continuous forming of ribs in sheet metal.

The method of first making an easily formed shape in a portion of a sheet by temporarily providing a semi-resilient edge portion on at least one side from which material can be laterally drawn through the rolls with the easily formed shape defined between two parallel bend lines gives the opportunity of re-shaping the material between said bend lines to provide cross-sections of varying profiles including profiles of complex cross-section in a minimum number of roll stands. The sheet metal can thus be readily drawn into suitable transitory shapes without the risk of splitting of the material or damaging its surfaces, particularly when precoated painted sheet is used and the said shapes may be re-shaped subsequently between the bend lines also without causing any damage to the material.

As in the present example, the initial rib should provide all the material required, between the bend lines, for the finally desired profile so that no further drawing in of metal is required and other parts of the sheet can be operated on while the initial rib is being re-shaped without disturbance from this re-shaping action. Successive contraction of parts of the sheet towards the center after the formation of an initial rib in those parts can therefore be avoided.

In FIG. 8 is shown an example of an alternative profile a plurality of which can be formed in a sheet by the method of the invention. It is a complex profile and is formed in a sheet 72, firstly by draw rolling the curved rib 74 (shown dotted) in the middle portion of the sheet between parallel bend lines 76 and secondly by re-shaping the material between said lines to form a slightly curved base 78 below the plane of the sheet 72 and two upstanding swages 80 and 82 as shown.

Claims

What is claimed is:

1. A method of shaping sheet metal in a single pass through a plurality of roll stands each having cooperating forming rolls to form a plurality of longitudinally extending profiles spaced laterally across the sheet, each profile being formed by the reforming in at least one roll stand of an initial rib, comprising the steps of,

a. forming a first initial rib in a first roll stand,

b. reforming the said first initial rib and forming at least one further initial rib laterally of the said first initial rib in a second roll stand, and

c. transforming as the sheet approaches each respectively of the said first and second roll stands at least a portion of the sheet into a valley cross-section, the apex portion of which is formed into the respective initial rib as the sheet passes through the respective roll stand, the valley cross section having a width greater than that of the initial rib,

each of the said initial ribs containing sufficient metal that the profile which is to be formed subsequently from it can be formed without further drawing in of metal from the rest of the sheet.

2. A method according to claim 1 wherein two of the said further initial ribs are formed in the second roll stand, one to each side of the said first initial rib.

3. A method according to claim 1 wherein each of the profiles subsequently formed from the said initial ribs is a pair of ribs, the said first initial rib being reformed into a pair of ribs in the second roll stand and the said at least one further initial rib being reformed into a pair of ribs in a third roll stand.

4. A machine for the draw roll forming of a plurality of longitudinally extending profiles in a metal sheet passed continuously through the machine including

a first roll stand having cooperating male and female forming rolls,

a second roll stand having cooperating male and female forming rolls,

the said male forming rolls of the first roll stand having a radially projecting part which cooperates with a radially recessed part in the female roll of the first roll stand to form an initial rib in the sheet as it passes through the first roll stand,

the said male-forming roll of the second roll stand having at least one radially projecting part which cooperates with a radially recessed part of the female roll of the second roll stand to form a further initial rib in the sheet as it passes through the second roll stand, the further initial rib being spaced laterally from the said first initial rib,

the said rolls of the second roll stand having cooperating parts which reform the said initial rib formed by the first roll stand without drawing in further metal from the rest of the sheet,

there being an axially extending coaxial support flange adjacent each side of each said radially projecting part, the diameter of at least one of the support flanges adjacent each said radially projecting part decreasing with distance from the said radially projecting part, the radially projecting part and the support flanges of the male roll and the radially recessed part on the female roll assisting in the transformation of the sheet as it approaches the roll stand into a valley cross-section having an apex portion which provides the strip of sheet from which the initial rib is formed as it passes through the roll stand.

5. A machine according to claim 4 wherein the said radially projecting part on each of the said male forming rolls has an arcuately curved periphery as seen in axial cross-section whereby the initial rib formed has an arcuate cross-section.

6. A machine according to claim 4 wherein each of the said female forming rolls has a coaxial flange at each side of the said radially recessed part, which flanges are opposed to and parallel to the said flanges of the respective male rolls in the nip of the male and female rolls, the flanges being spaced in the nip to allow metal to be freely drawn in laterally during the formation of the initial rib.

7. A machine according to claim 4 wherein the said cooperating parts of the rolls of the second roll stand which reform the initial rib formed in the first roll stand, are shaped to form a pair of ribs from the initial rib, there being a third roll stand having rolls including cooperating parts which reform the said at least one initial rib formed in the second roll stand into a further pair of ribs.

8. A machine according to claim 4 wherein the male roll of the second roll stand has two of the said radially projecting parts, one to each side of the part which reforms the initial rib made in the first roll stand, whereby two further initial ribs are formed in the second roll stand.