VOLD ROLF (NO)
PEDERSEN ROALD HELLAND (NO)
VOLD ROLF (NO)
| US5284360A | 1994-02-08 | |||
| DE4415246A1 | 1995-06-29 | |||
| DE4209094A1 | 1993-09-23 | |||
| US4094183A | 1978-06-13 | |||
| DE2117245A1 | 1971-10-28 | |||
| DE1652838A1 | 1971-11-04 |
| 1. | Rollover bar for a vehicle comprising a substantially Ushaped bent tube which either can be part of an active system assuming a retracted, passive position within a housing and via a mechanism an extended position giving protection against turning over, or to be part of a permanently mounted rollover bar system, characterised in that the rollover bar (1A) comprises a Ushaped bent tube (2) formed from one single piece of tube member (1) having two substantially parallel outer leg sections (2a, 2b) along with a middle bridge section (2c9 which is shaped partly be indentation of side areas (3a, 3b) and partly by inward bending (3c) of the bending side (3) Rollover bar according to claim 1 , characterised in that two parallel outer leg sections (2a, 2b) having retained the original dimension respective the diameter (D) of the original piece of tubing (1), while the shape of the bridge section or the midsection (2c) encompasses a width (B) that is less than the original diameter (D) of the piece (1), plus a height (H) that is equal, larger or smaller than the piece's diameter (D) Rollover bar according to claim 1 or 2, characterised in that there being found between the topbridge or bridge section (2c) and the substantially parallel leg sections (2a, 2b) respectively integral transition sections (4a, 4b), i e a section that is free of welds and intrusive connections 4 Rollover bar according to one of the preceding claims, characterised in that the middle bridge section (2c) exhibits substantially uniform crosssection along its longitudinal extent. |
| 2. | 5 Method for manufacturing a rollover bar for a vehicle, particularly a convertible car, comprising a substantially Ushaped bent tube which can either be part of an active system and assume a retracted, passive position in a housing and via a mechanism an extended, active position where the tubing extends over the housing and provides protection against rollover, or comprises part of a permanently assembled active rollover protection system, characterised in that the method comprises the following steps: a) provision of a straight, hollow tube shaped member (1) having a midsection (3) and side areas (3a, 3b), b) a tool (10a, 10b) is placed on each side of the midsection (3) to hold it fixed and indent the side areas (3a, 3b), simultaneously with or followed by a tool (11) indenting or bending inwards the "bending side" (3c) of said midsection (3), c) a tool (12a, 12b) is inserted into the track (3c) formed on the "bending side" (3c) of the midsection (3), simultaneously with the tool being divided (12a, 12b) for facilitating removal after bending , d) two bending tools are used, one on each side of the midsection 83), for example, cradleshaped tools, that press the outer end sections of the tube (2a, 2b) into the final Ushape while the topbridge 82c) simultaneously retains its inbent profile (3a, 3b, 3c). |
| 3. | 6 Method according to claims 5, characterised in that the bridge section or midsection (3,2c) is pressed in at the side areas 3a, 3b) to a width (B) that is less than the original diameter (D) of a tubeshaped piece (1) 7 Method according to claim 5 or 6, characterised in that the bridge section or midsection (3,2c) has its underside (3) bent inwards to a height (H) that is equal, larger or smaller than the original diameter (D) of a tubeshaped member (1 ) 8 Method according to one of the claims 57, characterised in that the divided tool (12a, 12b) that is inserted into the inbent track (3c) in the midsection (3) is made with rounded end sections (13a, 13b) which end sections (13,13b) after bending of the piece to the final Ushape are surrounded by the said inbent track (3c) over an angle of more than 90° and up to approx 180°. |
| 4. | 9 Method according to one of the claims 58, characterised in that the divided tool uses two mandrellike elements (12a, 12b) with an intermediate locking mechanism 10 Method according to one of the claims 59, characterised in that the middletopbπdge or bridge section (2c) and the substantially parallel leg section (2a, 2b) form respective integral transition sections (4a, 4b), i e a section that is free of welds and intrusive connections 11 Use of a rollover bar (1A) comprising a Ushaped bent tube (2) provided from a single piece of tube member (1 ) having two chiefly parallel outer leg section (2a, 2b) and a middle bridge section (2c) in a permanently mounted rollover bar system and/or an active system in a vehicle. |
The present invention concerns shaping of a roll-over tube, more specifically roll-over bars for a vehicle, and furthermore a roll-over bar which either can retract into a housing with a mechanism that allows for a mainly U-shaped section of the roll-over tube to assume a retracted, passive position within the housing, and an extended, active position where the tube extends over the housing and provides roll-over protection for the open vehicle, or being a part of a permanently mounted roll-over bar system
The invention furthermore concerns a process for the manufacture of such a roll-over bar
The invention also concerns use of such a roll-over bar
It has been previously known to manufacture U-shaped roll-over bars starting from two elongated tube-shaped members, which are joined into a U-shape by means of a top-bridge part that is preferably made of a length of tubing that has been bent to a U-shape with for the most part the retention of the same round shape, i e with a predominantly constant diameter, except for the areas of bending themselves, particularly the areas of curvature
From US 2,285,275 (Harder) a process is known for the bending of a tube having a sharp corner, i e approx 90°, so that the tube in the area is bent providing an inward bend, the tube being bent simultaneously while the tube is held fixed and clamped flat in the area of the inward bend and the bending area This method does not, however, indicate how U-shaped roll-over bars with the whole U-shaped part should be profiled Nor does the known process teach how a tool that is to be used for the simultaneous double-bending of a U-shaped tube should be designed and removed
From DE 4412108 (Zepnik/Porsche), a roll-over bar is known comprising frame components provided by internal high-pressure shaping However, such a piecewise assembled roll-over bar would result in cost-raising joints, for example, due to welding or gluing, along with the risk that the joints result in weak points in the assembled design
It is therefore an object of the present invention to provide a roll-over bar and a manufacturing process starting from an integral tube-shaped member and manufacturing a U-shaped tube in one piece A further object is to provide a cost-favourable manufacturing process compared with other manufacturing processes, for example known processes based on the welding of tube-shaped leg sections and an upper top-bridge
Another object of the invention is to provide a roll-over bar which gives a better security performance compared to the welded, previously known U-shaped roll-over bars
Still another object of the invention is to provide a process that provides a U-shaped roll-over bar where the shape of the top-bridge can be varied, while at the same time maintaining the structural strength properties improving these particularly in relation to the previously known welded roll-over bars
The benefits that are obtained from a roll-over bar formed in such a manner can be summarised as follows, particularly in comparison to welded roll-over bars:
a) The roll-over bar can take larger deformation specifically in tests for roll-over bars (roof compression test and longitudinal tension test) than the welded U-shape can take This particularly holds true on the bar side under tension in the roof compression test due to the geometry of the bend When the material is under tension, there is material in the indentation which is able to be pulled/stretched out so that in the first pass (production step) the material itself is not strained through a reduction in cross-section
b) By adjusting the geometry, the roll-over bar can more easily be integrated with other car parts, for example seats or headrests, than the corresponding bars consisting of round welded tubing This can be achieved for example by making the stem taller.
This type of bent roll-over bars can be used as permanently fixed roll-over bar systems as well as active systems
The present invention also provides a manufacturing method as defined in patent claim 5, comprising the following steps-
a) The process starts from a straight, substantially hollow tube-shaped member
b) A tool is placed on each side of the tube's mid-section for clamping and indentation of the tube's side areas, simultaneously with or followed by a tool indenting or bending in the "bending side" of said mid-section
c) A tool is applied being inserted into the track formed in the mid-section on the "bending side", for supporting the tube's mid-section in the in-bent track, simultaneously with the tool being divided for its removal after the bending operation
d) Two bending tools are applied, one on each side of the mid-section, for example, cradle-shaped tools that press the outer end sections of the tubing into the final U-shape while the top-bridge at the same time maintains its in-bent profiled shape
In an alternative modification of the manufacturing process according to the invention steps b) and c) could be interchanged so that the first step is to form the track 3c and then forming the side areas of the mid-section of the tubes (3a, 3b) This procedure may be advantageous due to less strain of the material during forming the mid-section area
The benefits which are achieved can be summarised as follows
a) Geometric design of the tube can ensure varying cross-sections by varying the indentation The indentation can be varied as much as possible optimally with respect to shape and function
b) Tube member can be shaped with a small bend radius, something which is otherwise difficult to obtain
c) From a cost point of view this process is far more favourable than the prior art joining of three pieces
d) The manufacturing is safer and the bent bar can be produced having a more uniform quality The number of process parameters is radically reduced
Additional benefits and features of the present invention will become evident from the following description referring to the attached drawings, and the accompanying patent claims
Fig 1 is a schematic side view of the upper portion of an exemplified
U-shaped roll-over bar manufactured according to the proposed technique
Fig 2 is a section taken along line A-A in Fig 1
Figs 3A, 3B show respectively a top view of a tube-shaped member inserted in a pressing tool, and a segment side view of the tube-shaped member, which may represent a first step of the production embodiment of the shaping process according to the invention
Figs 4A.4B show respectively, like Figs 3A and 3B, a top and side view of a second step in the shaping process, namely the indentation of the side areas of the member's mid-section
Figs 5A, 5B show respectively, like Figs 4A and 4B, a top and side view of the member during a third step in the shaping process according to the invention, where a tool for the inward bending of the bending side of the mid-section of the member is inserted and functions between parts of the pressing tool
Fig 6 is a side view, partially a sectional view that shows a fourth step in the shaping process according to the invention, where a divisible tool is inserted into the track formed on the bending side of the mid-section in order to support the member's mid-section while the tube-shaped member is bent into the final U-shape by means of a bending tool (not shown)
In Fig 1 an example is shown of a finished U-shaped bent roll-over tube manufactured according to the present invention The bent tube or the finished roll-over bar 1A has been manufactured starting from an integral, straight piece of tubing 1 with a given material thickness, i e with an appropriate external and respectively internal diameter D
The straight piece of tubing (member) 1 will upon appropriate bending into a U-shape be characterised by being manufactured in one piece avoiding welded parts, something which will in turn reduce the danger of fracture
The tube member 1 , which both before and after bending comprises two outer sections 2a and 2d, respectively, and a mid-section 2c, first has its middle section 2c processed by appropriate tools, where the mid-section 2c partly by indentation of side areas 3a and 3b, and partly by an inward bending 3c of the bending side 3, will assume an in-bent shape as it appears in Fig 2 An appropriate tool will act upon the bending side 3 of the mid-section 2c in order to form an inward-directed indentation, in that the degree of this indentation can be determined based on which final shape, extent and final dimensions the mid-section 2c needs to have
After the mid-section 2c has been formed with its in-pressed side areas 3a and 3b, and its inward-directed "bending side indentation" two halves of a tool which supports the mid-section during a bending process area where the legs of the tube 2a and 2b are brought towards each other, into the final U-shape of the tube member 1 , in the manner shown in Fig 1
The bending of the legs 2a and 2b of the tube member can be appropriately performed by cradle-shaped tools that press the end sections of the tube into the final U-shape, simultaneously with the two halves of the tool placed in the track or indentation 3 of mid-section 2c giving good support of the mid-section during this bending process The two halves of the tool can then be split apart and removed upon finalising the bending into the final U-shape
In Figs 3A, 3B, 4A, 4B and 5B, along with Fig 6 different steps are shown in a preferred mode of operation for shaping of a U-shaped roll-over tube for use in a roll-over bar
Figs 3A and 3B show respectively a top view of a tube member 1 inserted into a pressing tool 10a and 10b, and a segment of a side view of the tube member 1 , which may represent a first step in the production method according to the invention
It must be understood that the shaping process preferably can start from a substantially hollow tube-shaped member with an external diameter D, but it should be understood that other hollow members that can be defined as tube-shaped can also be used, all depending upon the final design of the finished bent U-shaped roll-over bar
Figs 4A and 4B show respectively, like Figs 3A and 3B, a top view and a side view of a second step in the shaping process, namely indentation of side areas 3a and 3b of the member's mid-section to a narrower width B than the original diameter D
In these Figures along with Figs 5A and 5B, it is shown that a two-part tool 10a and 10b is placed on each side of the mid-section 3 for clamping and pressing in of side areas 3a and 3b, simultaneously with or after which a tool 11 indents or bends in "the bending side" 3c of said mid-section 3 to a dimension H that can be larger, equal to or less than the original diameter D
In Fig 6 it is shown that a tool 12a and 12b is used which is inserted into the track or indentation formed in the "bending side" 3c to support the tube's mid-section in the in-bent track 3c, while at the same time the tool is divided, 12a and 12b, in order to facilitate removal after bending
According to an advantageous embodiment of the method the divided tool 12a and 12b that is inserted into the in-bent track 3c formed in the mid-section 3 being made with rounded end sections 13a and 13b, which end sections 13 and 13b after the bending of the piece to the final U-shape are surrounded by the said in-bent track 3c at an angle of more than 90°, and up to approx. 180°.
Furthermore, the divided tool comprising two mandrel-like elements 12a and 12b with an intermediate locking mechanism may be utilised.
As it appears from Fig. 6 two bending tools can also be used, one on each side of the mid-section 3, for example, cradle-shaped tools which press the end sections 2a and 2b of the tube into the final U-shape simultaneously with the top-bridge 2c having retained the in-bent profile 3a, 3b and 3c.
It is advantageous for the middle bridge section 2c to exhibit substantially uniform cross-section along its longitudinal extent, however variations in the extent of the bending can also be contemplated here.
the shape of the mid-section 2c which constitutes the top-bridge of the final U-shape of the roll-over bar 1 A can be varied within broad limits, in that it must be understood that the width B of the mid-section or the top-bridge 2c shown in Fig. 2 can have a smaller dimension than the original external diameter D shown in Fig. 1. Consequently, there will occur between the top-bridge 2c and each of the legs 2a and 2b a transition section, 4a and 4b respectively, but since the piece for the finished roll bar 1 is formed from a single piece, these transition sections 4a and 4b will be free of welds and compared to welded joints exhibit an increased reliability bridge 2c and the associated leg sections 2a and 2b.
Furthermore it will be understood that the in-bent material 3c in the top-bridge 2c can sustain more deflection than a corresponding top section made by ordinary fitting and welding, which gives an increased safety upon the turn-over of the vehicle in which the roll-over bar is installed.
A roll-over bar 1A according to the present invention will also more easily be able to be integrated into a headrest, since the dimensions of the top-bridge can more easily be adjusted for the different versions of headrests, while at the same time the resistance to fracture can be improved compared to previously known roll-over bars.
Tests have shown that the present roll-over bars in trials conducted according to the "Federal Motor Vehicle Safety System" FMVSS 216 exhibit favourable fracture resistance compared to welded U-shaped roll-over bars (excellent strength to ductility ratio).