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Patent Searching and Data


Title:
A YIELDABLE POLE AND A METHOD OF MAKING SUCH POLE
Document Type and Number:
WIPO Patent Application WO/2008/127168
Kind Code:
A1
Abstract:
A safety pole which is yieldable has been roll formed to a polygonal cross-section and has only one longitudinal joint (11). Alternatively, two halves can be roll formed separately and welded together to a pole. A few or all polygon sides or the corners have inward folds (31-35) which provide three layers of sheet and stiffens the pole, but does not prevent the pole from being yieldable when run into by a vehicle. The inward fold forms a centre slot (30) which is aired by the wind. The stiffeners can alternatively be situated externally instead of internally.

Inventors:
INGVARSSON LARS (SE)
Application Number:
PCT/SE2008/000196
Publication Date:
October 23, 2008
Filing Date:
March 14, 2008
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
ORTIC 3D AB (SE)
INGVARSSON LARS (SE)
International Classes:
E01F9/018; B21C37/00; E01F9/011; E04H12/08
Foreign References:
EP0994982B12004-03-24
GB2342603A2000-04-19
US3987593A1976-10-26
CH360191A1962-02-15
US3196990A1965-07-27
Other References:
See also references of EP 2147161A4
Attorney, Agent or Firm:
ASLUND, Roland (Box 99, Krylbo, SE)
Download PDF:
Claims:

Claims

1. A method of manufacturing a yieldable pole with polygonal or round cross-section and longitudinal stiffeners (31-35; 41-45) on at least portions of its periphery, characterised in that the entire cross-section of the pole or portions of it is/are roll formed from a flat blank respectively from flat blanks and longitudinal folds (31-35; 41-45) are formed which make said stiffeners, and finally the joint (11) respectively the joints are finalized.

2. The method according to claim 1, characterised in that the folds (31-35) are formed inwardly and allows the slot (30) which is formed to be open outwardly.

3. The method according to claim 1 or 2, characterised in that the folds are formed so that they will be symmetrical and flattened along the pole wall so that the pole wall provides three layers of sheet on at least a portion of the periphery.

4. The method according to any one of the preceding claims, characterised in that the pole is roll formed to have a varying cross-section.

5. The method according to claim 4, characterised in that the pole is roll formed to have a continuously decreasing cross-section in one direction.

6. The method according to claim 2, characterised in that the pole is roll formed to a polygonal cross-section with the slots in the corners.

7. A yieldable pole with polygonal or round cross-section of sheet metal, which has longitudinal stiffeners (31-35; 41-45) on at least portions of its periphery (16-19), characterised in that the stiffeners are folds (31,35,41-45) which make three layers of sheet on at least a portion of the periphery of the pole.

8. The pole according to claim 7, characterised in that the folds (31 -35) are inwards the pole with open slots on the outside of the pole.

9. The pole according to claim 7 or 8, characterised in that it has a varying cross- section along its length.

10. The pole according to claim 9, characterised in that it has a continuously decreasing cross-section in one direction.

11. The pole according to claim 10, characterised in that a lower portion of the pole has a constant cross-section whereas an upper portion of the pole has a conically decreasing cross- section.

Description:

A yieldable pole and a method of MAKING SUCH POLE *

Technical field

The present invention relates to a method of manufacturing a yieldable pole with polygonal or round cross-section and longitudinal stiffeners on at least portions of its periphery. The invention also relates to such a pole.

Background and object of invention

Light posts and other poles along the roads have conventionally been so strong that they have not yielded when run into and they may have caused such great damage on the colliding vehicle that passengers have been killed by the poles. Yieldable poles are commonly called safety poles. EP-0994982 describes a safety pole with polygonal cross-section consisting of two halves of sheet metal which have been joined. Every polygon side has a longitudinal reinforcement in form of a flat steel bar which is fastened with a thermoplastic to the sheet. This pole is sturdy and withstands wind forces, and it yields when run into.

It is an object of the invention to provide a safety pole, which is easier and cheaper to produce than prior art poles.

Brief description of the invention

The objects of invention are fulfilled with a pole where the stiffeners are folds which provide three layers of sheet on at least a portion of the periphery of the pole.

According to the invention, the entire cross-section of the pole or portions of it is/are roll formed from a flat blank respectively from flat blanks and longitudinal folds are formed which make said stiffeners, and finally the joint respectively the joints is/are finalized.

The invention is defined by the claims.

Brief description of the drawings

Figure 1 is a side view of an inventive pole

Figure 2 is a cross-section along the line 2-2 in figure 1.

Figure 3 is a cross-section along the line 3-3 in figure 1.

Figure 4 corresponds to figure 3 but shows a modified cross-section

Figures 5-7 are sections of a pole with alternative cross-section where

Figure 5 corresponds to figure 2,

Figure 6 corresponds to figure 3, and

Figure 7 corresponds to figure 4.

Figures 8-10 are sections of a pole with modified cross-section where

Figure 8 corresponds to figure 2,

Figure 9 corresponds to figure 3, and

Figure 10 corresponds to figure 4.

Figure 11-13 are sections of a pole with modified cross-section where

Figure 11 corresponds to figure 2,

Figure 12 corresponds to figure 3, and

Figure 13 corresponds to figure 4.

Figures 14-17 are cross-sections of alternative pole designs.

Description of illustrated examples of the invention

Figure 1 shows a pole which for example may be a lamp post. The pole is conically tapered upwards. It has a polygonal cross-section and is octagonal, but may have another number of corners. It is roll formed from a sheet metal strip and has a sole longitudinal joint 11. The polygon sides are indicated at 12-19 and the corners between the polygon sides are indicated at 20-27. The cross-section is symmetrical.

Every other polygon side 12-15 is flat and every other side 16-19 has an inward fold which will be described with reference to the polygon side 18. Centrally on the side, the sheet is folded inwards in both directions so that a slot 30 is formed on the centre of the side and the inwards folded portions 31,32 extend in different directions along the side and fold back in bends 34,35 to a common portion 36 so that the biggest portion of the polygon side provides three layers of sheet steel, but the side has a single sheet closest to the corners. It may be advantageous, but not necessary, to have a single sheet closest to every corner on at least one tenth of the width of the pole on at least a part of the length of the pole - the lower part which

may be run into. It is advantageous that the inward fold extends in both directions and is symmetrical, but this is not an absolute necessity.

Figure 3 shows that the inward fold 31-35 has the same size along the whole length of the pole in spite of the polygon side 18 diminishing upwards. Figure 4 shows a modified embodiment where also the width of the inward folds decreased upwards.

At roll forming, the slots are inevitable but can be formed very narrow. It is impossible to form them completely tight, but it is advantageous that there are slots so that the inward folds 31-35 are aired by the wind.

The longitudinal joint can be welded, suitably laser welded, directly in the roll forming machine. The pole can be manufactured from hot-dip galvanized sheet steel. Then, the zinc heals the laser weld and additional surface treatment is not required. It is also possible to make the pole from coil coated sheet steel and place the painted sides of the edges of the joint together and heat the paint so that the joint is glued by the paint. UV hardened glue can also be utilized. Alternatively, the joint could be folded or made in another way and the pole could be made from stainless sheet steel.

The inward folds 31-35 are reinforcements or stiffeners that provide sturdiness to the pole so that it withstands wind forces. The corners, not being reinforced, are easily deformed when run into and initiate the deformation of the pole so that the pole by yielding takes up collision energy and decelerate the colliding vehicle relatively smoothly.

The figures 5-7 show a pole modified such that all polygon sides have inward folds and not every other side as in preceding figures. The joint 11 is then not placed on the centre of a side but in a corner.

The shown example embodiments according to figures 1-7 show a pole of conical shape. The simplest way to manufacture a pole is with a constant cross-section along its length since the machine will be the least complicated. A machine for manufacturing a conical pole with constant size of the inward fold 31-35 along the length of the pole is slightly more

complicated. A further more complicated machine is required for manufacturing a conical pole with varying size of the inward fold. The upper portion of the pole does not always need reinforcements in the form of inward folds, but to completely end the inward folds and have an upper portion without inward folds requires a still more complicated machine. It is also possible to roll form a pole with a constant cross-section on a lower portion and with a conical upper portion.

The shown embodiments seem to be suitable compromises for the manufacturing of a pole of good characteristics and low weight with a not too complicated and expensive machine.

Figures 8-10 and 11-13 respectively show two example embodiments where the stiffeners are located on the outside of the pole.

The pole according to figure 8 has a similar stiffener in the form of a fold as the pole of figure 2, but the fold in figure 8 is external and has been given reference numerals 40-45 which correspond to reference numerals 30-35 in figure 2. Since the folds are similar, they are not particularly described for figure 8, but reference is made to figure 2. The joint 11 is shown extending outwardly in figure 8, but could suitably be made extending inwardly as shown in figure 2.

Figure 9 shows a fold 41-45 which is the same along the side of the pole although the polygon side becomes narrower, and figure 10 shows a modification where the fold tapers as the polygon side tapers.

Figure 8 shows a fold on every other polygon side. In figure 11 , a fold is shown on every polygon side but the two variations are otherwise similar.

Figures 14-17 show examples of alternative cross-sections with folds in the corners instead of on the sides. The poles according to these embodiments may have a different number of polygon sides and a reinforcement fold on every corner or have one or more corners without folds between the corners which have folds. With that many polygon sides that are shown, the pole gives the impression of being round. The corners either have a slot or lacks folds, which

results in that the comers of the pole can be deformed when run into and can initiate further deformation.

The roll forming can be made from a coiled flat strip which is both cut lengthwise and on the sides directly in connection with the roll forming, but can also be made from pre- manufactured individual flat blanks.

In the shown embodiments, the entire cross-section of the pole is formed in one roll forming operation. Alternatively, two blanks can be roll formed to two half sections in two roll forming operations and then be joined, preferably by two longitudinal welds. A roll forming machine to roll form half the cross-section will be simpler and cheaper than a machine to roll form an entire cross-section. Alternatively, three of more portions can be roll formed and then joined by longitudinal joints.