CN86103634A - A pole specially used to support electrical or telephone lines - Google Patents

Abstract

The cylindrical shell (1) encloses a longitudinal and hollow interior (2). The housing (1) comprises two coaxial walls (4, 6) made of longitudinal fibre-reinforced plastic. The two walls are joined by a low density felt pad (7). It is used to make a light pole with good bending resistance.

Description

A pole specially used to support electrical or telephone lines

The invention relates to a pole, in particular to a pole for supporting electric wires or telephone lines.

It is known how to make light poles, especially metal poles, by making their structure tubular. However, the weight reduction achieved with this method is relatively limited. In fact, these electric poles are often subjected to combined compression and bending loads, so they are prone to longitudinal bending, that is, the electric poles produce sudden bending, and this sudden bending is especially easy to occur at the embedded position, that is, the vicinity of the bottom. However, thin-walled tubular parts are difficult to prevent this danger due to the effect of the so-called "casing". These poles can be bent longitudinally at far lower loads than would be derived from a purely moment of inertia calculation.

It is an object of the present invention to provide a pole which is particularly light in weight with respect to its ability to withstand combined compression-bending loads.

According to the invention, the pole, in particular a pole for supporting electric or telephone lines, comprises a longitudinal and hollow inner space enclosed by a casing, characterized in that the casing is formed by a relatively rigid The inner wall is composed of an outer wall, the outer wall is separated from the inner wall by a certain distance in the radial direction, and surrounds the inner wall, and there are connecting means between the inner and outer walls, and the outer wall also contains fibers, which extend along the obvious tangential direction , and form an angle with the longitudinal axis of the pole.

In this way, even if the two walls are very thin, longitudinal bending is only possible when the load is large. In fact, the means of connection prevents the two walls from deforming independently of each other, so that the shell has a large local moment of inertia at every position around it. On the contrary, even if the urgent moment of inertia is large, the local moment of inertia is small, which is still enough to make the existing electric pole bend under a relatively small load. The tangential fibers at an angle to the longitudinal axis of the pole prevent cracking of the outer wall, especially when the pole is operated with twisting (torsional deformation).

The advantages of other features of the present invention will also be elucidated in detail in the following description.

Now introduce accompanying drawing, this accompanying drawing is only the example of the present invention, and the present invention is not limited thereto:

Fig. 1 is a schematic diagram of a longitudinal section when a pole of the present invention is partially cut;

Fig. 2 is a perspective view when the pole of Fig. 1 is partially cut;

Fig. 3 is the detailed view of the III position among Fig. 2, and it is in a transverse section;

Fig. 4 is a cross-sectional view of the second embodiment of the pole;

Fig. 5 is the detailed diagram of V position in Fig. 4;

Fig. 6 is a perspective view with a partial cutaway of the third embodiment of the pole;

Fig. 7 is the scaled detailed view of the VII position in Fig. 6;

Figure 8 is a cross-sectional view of a fourth embodiment of a pole; and

FIG. 9 is a detailed view on an enlarged scale of part IX in FIG. 8 .

The pole shown in FIG. 1 comprises a housing 1 of cylindrical shape enclosing a longitudinal and hollow inner space 2 . The lower end of the pole is inserted, that is, embedded in the soil.

Such poles may be, for example, poles supporting electrical or telephone lines. Therefore, the pole bearing force has its own weight, the weight of the wire, and the horizontal stress caused by wind or the mechanical tension caused by the wire being erected in a non-straight direction in the horizontal plane, for example. stress. The result is a horizontal stress FL, which acts near the upper end of the pole, and a vertical stress Fh, which is generally offset from the pole's axis. This combination of compression and bending loads can easily cause the pole to bend slightly above its fixed part. In order to remedy this defect, according to the invention, the housing 1 of the pole comprises a very rigid inner wall 4 adjoining the above-mentioned space 2 and an outer wall 6 radially spaced from the inner wall and surrounding the inner wall. The two walls 4, 6 are connected by connecting means which securely hold each wall, thereby preventing deformation of one wall relative to the other. In the examples shown in Figures 1 to 3, the attachment means is a padding such as foam or felt.

As shown in FIG. 3, each of the two walls 4 and 6 is made of plastic containing reinforcing fibers extending in the longitudinal direction of the pole. The two walls 4 and 6 are preferably produced by a pultrusion method, i.e. an extrusion-type process in which the product is pulled out of the extruder by pulling the reinforcing fibers during extrusion, In order to maintain the orientation of the reinforcing fibers.

Furthermore, the outer wall 6 contains fibers 11 arranged in random order, so that some fibers are arranged in a distinct tangential direction and form an angle with the longitudinal axis 12 of the pole (Fig. 1). In particular some of the fibers 11 extend in a distinct circumferential direction.

It is even better if the two walls 4 and 6 are made together by connecting means 7 . In fact, the consideration of the present invention is to make the felt pad tube in the pultrusion machine, make the felt pad tube lead in the direction of the die hole axis of the pultrusion machine, and then draw the felt by the two walls 4, 6 and the sandwiched between them. The whole composed of the gasket tube completes the pultrusion operation from the direction. In this way, there is an extremely strong adhesion between each face of the felt tube and its adjacent wall 4 or 6, since the plastic penetrates into the surface of the felt during extrusion.

To make tubes of felt, foam or other material, one can combine the strips longitudinally side by side, or close up strips with a width equal to the circumference of the tube, or arrange the strips in a spiral shape. Roll up.

During the pultrusion process, the longitudinal fibers are distributed to one wall or the other, guided in coaxial layers, and can even be distributed in the thickness of each wall. In the outer wall 6, therefore, fibers 11 can be selectively placed in any sequence arranged between the longitudinal fibers for the outer wall.

If the connection means 7 are made of foamed plastic, one can make the two walls 4 and 6 separately, then position the wall 4 in the wall 6 and inject the foamed plastic between the two walls. The selection of the foamed plastic should pay attention to its adhesion to the plastic walls 4 and 6 and its strength against shear stress.

In the example of FIGS. 4 and 5 , the inner wall 4 and the connection means 7 remain unchanged. However, the outer wall 6 is formed by winding the fibers around the connecting means in the circumferential direction of the garden. As is known, fiber winding is the winding of a resin-impregnated multi-strand fiber rope around a core.

In the example of FIGS. 6 to 9 , the connecting means 7 consist of a bridge 8 connecting the two walls 4 and 6 . In the described embodiment, the bridge 8 is a reinforcing rib which extends axially over the entire length of the mast.

In the example of FIGS. 6 and 7 , the two walls 4 and 6 are integrated by ribs 8 . This whole consists of plastic reinforced by fibers extending longitudinally of the pole. This monolithic structure can be done in one pass by pultrusion operation.

In addition, the outer wall 6 is sandwiched with a fiberglass fabric 13 along its circumference at half its thickness. Due to the nature of the fabric, the fabric 13 must contain fibers that are bent tangentially and form an angle with the axis of the pole. The insertion of the fabric 13 can be done by positioning in the extruder relative to the longitudinal fibers.

In the example of FIGS. 8 and 9 , the inner wall 4 is completed in one piece with ribs 8 consisting of longitudinal fiber-reinforced plastic, this integration being possible by extrusion as in FIGS. 6 and 7 .

However, the outer wall 6 is formed by winding fibers resting on top of the ribs 8 . Therefore, the outer wall 6 has a polygonal cross-section whose apex coincides with the apex of the rib 8 .

In all the examples that have been described, the walls 4 and 6 can be made very thin and the connecting means can be made very light, either because of their low density (felt or foam) or because of the space left between them. void (reinforcing rib 8). But in any case the local moments of inertia are greatly increased. The so-called local moment of inertia refers to the moment of inertia of a certain part of the circumference of the beam section. For example, the moment of inertia of the part surrounded by rectangle 9 in FIG. 3 is more accurate, and the minimum inertia correction around the axis 11 is the object to be considered. The so-called moment of inertia of a certain part of the face refers to the moment of inertia of this part except the support that makes it supported by the rest of the section. According to the appearance of the present invention, the moment of inertia of the section around the axis 11 such as 9 is much shorter than that of the corresponding part of the single-wall pipe of equal weight. Due to the increase in the local moment of inertia at each point around the profile, it is impossible to produce the initial deformation which is necessary to produce longitudinal bending in the compression region of the beam.

Of course, the invention is not limited to the examples described and shown, many modifications being possible to these examples without departing from the scope of the invention.

Thus, the invention may also be carried out by methods other than pultrusion in the manufacture of walls 4 and 6 .

In the example of FIGS. 6 and 9 , a felt-like or foam-like material can be used in the circumferential spaces between the ribs 8 .

In the embodiment of FIGS. 1-3 , tangential fibers may be implemented with the fabrics of FIGS. 6 and 7 . Likewise, the fibers in any order of FIGS. 1 to 3 may be used as tangential fibers made in the embodiment of FIGS. 6 and 7 . Besides this, one can also realize tangential fibers in two embodiments (Figs. 1 to 3, 6 and 7) by winding fiber ropes around the extruded wall, which then contains only longitudinal fibers.

Claims (10)

1. A pole, especially a pole for supporting electrical or telephone lines, comprising a longitudinal and hollow interior space (2) enclosed by a housing (1), characterized in that the housing (1) It includes an apparently rigid inner wall (4), and an outer wall (6) radially spaced from the inner wall (4) and enclosing the inner wall (4), located between the outer wall (6) and the inner wall (4) The connecting means (7), and the outer wall (6) contains fibers (11), the fibers extend along the obvious tangential direction and form an included angle with the longitudinal axis (12) of the pole. 2. Electric pole according to claim 1, characterized in that the fibers consist of fiber ropes which surround the connecting means (7) and are wound in a substantially circumferential direction. 3. A pole according to one of claims 1 or 2, characterized in that the fibers consist of fibers (11, 13) impregnated in a plastic. 4. A pole according to one of claims 1 to 3, characterized in that the inner wall (4) and at least a part of the outer wall (6) are integrally formed with the connecting means (7). 5. A pole according to one of claims 1 to 4, characterized in that the connecting means (7) consist of bridges extending between the two walls (4,6). 6. A pole according to claim 5, characterized in that the bridge (8) is a stiffener extending longitudinally between the two walls (4,6). 7. A pole according to claim 6, characterized in that the rib (8) is integrally formed with at least one of the walls (4, 6). 8. A pole according to claim 7, characterized in that the walls (4) and ribs (8) consist of plastic containing fibers extending significantly along the length of the pole. 9. A pole according to one of claims 1 to 4, characterized in that the connecting means (7) consist of a low-density material such as felt or foam. 10. Pole according to one of claims 1 to 9, characterized in that at least the inner wall (4) is made of plastic by pultrusion.

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