Road structure – process – or apparatus – Traffic director – Yielding
Patent
1983-07-14
1986-01-14
Leppink, James A.
Road structure, process, or apparatus
Traffic director
Yielding
40608, 264146, 264150, 72367, 493288, 493293, 493339, E01F 901
Patent
active
045643091
DESCRIPTION:
BRIEF SUMMARY
The invention of this application is disclosed in International Application No. PCT/SE82/00398, filed Nov. 25, 1982, under which priority is claimed under 35 USC 119.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a post for use as a roadside marking post, a traffic sign post, a lamp post, or for other comparable applications in a road traffic environment, and of the kind which is self-raising after having been hit by a vehicle. More specifically, the invention relates to posts of these kind which are made from a channel-shaped plastic profile, the channel-shaped side of which is facing away from the traffic, and which has, at least along its bending zone, a substantially arcuate cross-section.
2. Description of the Prior Art
Self-raising posts of the above kind are known from the U.S. Pat. No. 4,084,914. Posts according to that publication are in the form of a plastic profile which is substantially U-shaped, that is, it consists of two side portions and a flat middle portion therebetween. Unless the angle between the side portions and the middle portion is very obtuse, a bending of a post of this type will cause the material in the side portions to be folded as illustrated in the appended FIG. 1, causing material fatigue which might cause the material to break. It has been suggested, in order to reduce these concentrations of tension in the bending line area of the post, to make the post with an arcuate cross-section. In order to obtain a sufficient strength in the longitudinal direction, this known post is provided, at the channel-shaped innerside, with a reinforcement profile connected to the post by means of rivets or the like.
It has been found that a post of this type will not be self-raising if subjected to a bending of approximately 90.degree., since the upper, bent-around portion of the post is too long and too heavy to allow the springyness of the material to raise the post back up.
Another disadvantage with the known post is that in order for it to resist the stresses it might be subjected to it has to be made from a comparatively expensive plastic material, namely polycarbonate, which has good strength properties but requires a considerable thickness of the material. Furthermore, this material causes great wear on the extrusion moulding tools used for manufacturing the posts.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a post of the kind set forth above, which will have the property of self-raising, even if the post should be bent more than 90.degree. and even if this occurs several times along the same line of folding. It is a further object of the invention to provide a post of this type which may be manufactured from an inexpensive plastics material, for instance PVC, without imparing the strength of the post. These and other objects have been attained by making the cross-sectional area of the post progressively increasing towards the lower end, whereby the flaring-out zone formed upon bending of the post will be larger, and thus the inherent resiliency of the material will be greater, below than above the folding line. The invention also relates to a method of manufacturing posts of this kind. The method is mainly characterized in that a tube of a PVC-based impact resistant plastics material is formed by extrusion, that the extruded tube is cut into lengths corresponding to the length of the posts to be manufactured, and that the tube lengths are split along at least one diagonal line which is either straight or composed of several line parts.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in detail with reference to the accompanying drawings wherein:
FIG. 1 is a view in perspective of a previously known post of the type which has been referred to in the introductory part of this specification, the post being shown in a bent condition;
FIG. 2 is a view similar to FIG. 1 of a post according to the invention, also shown in a condition bent around at an angle of approximately 90.degree.
REFERENCES:
patent: 1599066 (1926-09-01), Rushmore
patent: 1754771 (1930-04-01), Kirschbraun
patent: 2121961 (1938-06-01), Gill
patent: 2848747 (1958-08-01), Dixon
patent: 3553303 (1967-12-01), Zavasnik
patent: 4036666 (1977-07-01), Mlavsky
patent: 4084914 (1978-04-01), Humphrey et al.
patent: 4092081 (1978-05-01), Schmanski
patent: 4245922 (1981-01-01), Auriemma
Hjorth Beverly E.
Leppink James A.
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