JP4959148B2 - Telescopic boom for aerial work platforms - Google Patents

Description

  The present invention relates to a telescopic boom for an aerial work vehicle including a boom using FRP as a part of a boom stage of the telescopic boom.

  In an aerial work vehicle used for electrical work, the work bench installed at the tip of the telescopic boom may come into contact with the live line, so that the telescopic boom is required to have electrical insulation. For this reason, a technique is adopted in which some boom stages constituting the telescopic boom are made of FRP having excellent electrical insulation. As a part of the boom stage of the telescopic boom being constituted by FRP, the entire cross section is constituted by FRP (hereinafter referred to as “FRP boom”), and the surface of the steel plate boom is lined by FRP (hereinafter referred to as “FRP boom”). "FRP lining boom") is known.

  As a slide device for a telescopic boom in which the FRP boom is telescopically inserted, a slide plate having a shape corresponding to the outer surface of the corner of the FRP boom is attached to the inner surface of the tip of the outer boom so as to contact the outer surface of the corner of the FRP boom. Is known (for example, see Patent Document 1).

FIG. 5B is a cross-sectional view of the overlapping portion of the telescopic boom 4 described in Patent Document 1, and FIG. 5A is a partial enlarged view of the sliding device of the telescopic boom 4. The front boom 4c and the intermediate boom 4b into which the front boom 4c is fitted are rectangular in cross section. The front end boom 4c has an entire cross section formed of an FRP material for the purpose of electrical insulation, and each corner portion C is rounded. 8 is a slide plate provided at the four corners inside the tip of the intermediate boom 4b. The shape of the slide plate 8 is such that the sliding surface F is rounded corresponding to the outer corner portion C of the tip boom 4c. It is located so as to contact each corner of the boom 4c.
Japanese Utility Model Publication No. 4-34297 (Patent 5-7, Fig. 1)

  As is widely known, FRP has plastic as a main component and is vulnerable to temperature rise. Therefore, when a boom using FRP is supported by a slide plate, it is necessary to manage temperature rise due to frictional heat. In order to suppress the temperature rise as much as possible, it is effective to increase the area of the sliding contact surface supported by the slide plate and to equalize the surface pressure so that the maximum surface pressure is as low as possible.

  However, the vicinity of the corner portion C of the tip boom 4c shown in FIG. 5A shown in FIG. 5A has a high cross-sectional rigidity, and therefore the surface pressure of the sliding surface near the corner portion C of the corresponding slide plate 8 is high. Tended to be. Moreover, since the lower surface part of the front end boom 4c has a linear shape, the rigidity decreases as it approaches the center, and the surface pressure of the sliding contact surface with the slide plate 8 tends to decrease.

  Therefore, when the tip boom 4c is expanded and contracted with respect to the intermediate boom 4b, the temperature rises due to friction at the corner portion C where the surface pressure is high even if lubrication with grease is performed, and the response of the FRP constituting the tip boom 4c There was a risk that cracks and damage would occur in the parts to be damaged.

  Therefore, the present invention adopts a slide plate support structure that has an optimal cross-sectional shape and is adapted to the cross-sectional shape of the FRP boom or FRP lining boom, thereby sliding the FRP boom or FRP lining boom. It is an object of the present invention to provide a telescopic boom for an aerial work vehicle that can take a large area of a sliding contact surface of a supporting slide plate and can equalize the supporting surface pressure.

The telescopic boom of an aerial work vehicle described in claim 1 of the present application is intended for an telescopic boom of an aerial work vehicle including an FRP boom having an entire cross section made of FRP as a part of a boom stage of the telescopic boom. To do. The outer cross-sectional shape of the FRP boom includes a side surface portion parallel to each other and a lower surface portion that is an isosceles trapezoid that protrudes downward, and the isosceles trapezoid shape has a trapezoidal top portion whose hypotenuses on both sides are in the center. approximately the same length as the longer one to be formed, the FRP boom fitting inserted is the tip lower surface portions the inner surface of the outer boom hypotenuse portion of the isosceles trapezoid the slide plate for slidably supporting the hypotenuse portion of the isosceles trapezoid in which characterized in that disposed.

Furthermore, the telescopic boom of an aerial work vehicle described in claim 2 of the present application is an aerial work vehicle including an FRP lining boom obtained by lining the surface of a steel plate boom with FRP as a boom stage as a part of the telescopic boom. For telescopic booms. The outer cross-sectional shape of the FRP lining boom includes a side surface parallel to each other and a lower surface portion that is an isosceles trapezoid protruding downward, and the isosceles trapezoid shape is a trapezoid whose hypotenuses on both sides are central. while being longer than the top, approximately the same as the FRP lining boom fitting inserted is the tip lower surface portions the inner surface of the outer boom hypotenuse portion of the isosceles trapezoid the slide plate for slidably supporting the hypotenuse portion of the isosceles trapezoid It is arranged by length .

Moreover, the telescopic boom of the aerial work vehicle described in claim 3 of the present application is characterized in that a slide plate that slide-supports the side surface of the FRP boom or FRP lining boom according to claim 1 or 2 is arranged. And

In the telescopic boom of the aerial work vehicle according to claim 1, the outer cross-sectional shape of the FRP boom is a shape of a side surface parallel to each other and a bottom surface of an isosceles trapezoid that protrudes downward, so that the rigidity of the bottom surface is low. It will be expensive. And since the said lower surface part was slidably supported by the slide plate of the substantially same length as the hypotenuse part of an isosceles trapezoid, the surface pressure of a slide plate slidable surface can be equalized. Further, by equalizing the surface pressure of the sliding contact surface, as a result, the portion that can be effectively supported can be enlarged, and the area of the sliding plate sliding contact surface can be increased.

In the telescopic boom for an aerial work vehicle according to claim 2, the cross-sectional outer shape of the FRP lining boom is a shape of a side surface parallel to each other and a bottom surface of an isosceles trapezoid that protrudes downward. Is expensive. And since the said lower surface part was slidably supported by the slide plate of the substantially same length as the hypotenuse part of an isosceles trapezoid, the surface pressure of a slide plate slidable surface can be equalized. Further, by equalizing the surface pressure of the sliding contact surface, as a result, the portion that can be effectively supported can be enlarged, and the area of the sliding plate sliding contact surface can be increased.

The shape of the lower surface portion of the isosceles trapezoid protruding downward from the FRP boom or FRP lining boom described in claims 1 and 2 is easy by simply adding two bent portions to the lower surface portion compared to the conventional rectangular cross section. Can be formed. Therefore, it is suitable as the outer cross-sectional shape of the FRP boom or FRP lining boom, and there is no technical difficulty in carrying out the same, and no major equipment change is involved.

In the telescopic boom of the aerial work vehicle described in claim 3 , since the slide plate for slidingly supporting the side surface portion of the FRP boom or FRP lining boom is disposed on the inner surface of the side surface portion of the outer boom, the FRP boom or The cross-sectional deformation of the side part of the FRP lining boom can be suppressed. Accordingly, deformation of the lower surface portion connected to the side surface portion is also suppressed, so that the surface pressure of the sliding contact surface of the slide plate that supports the lower surface portion in sliding contact can be further equalized.

  FIG. 1 shows an aerial work vehicle X using an extendable boom according to an embodiment of the present invention. The aerial work vehicle X has a swivel base 3 mounted on a vehicle unit 1 having an outrigger 2 so as to be turnable, and a telescopic boom 6 is pivotally attached to the turntable 3 so as to be able to move up and down. A hoisting cylinder 5 is interposed between the telescopic boom 6 and the swivel base 3, and the hoisting cylinder 5 moves up and down by the hoisting cylinder 5. A work table 11 is swingably connected to the tip of the telescopic boom 6. The work table 11 is maintained in a horizontal posture by a leveling device (not shown) regardless of the up-and-down movement of the telescopic boom 6.

  The telescopic boom 6 is a three-stage boom configured by inserting a second boom 12 into a base boom 11 and inserting a top boom 13 into the second boom 12. A telescopic device (not shown) is built in the telescopic boom 6, and the telescopic boom 6 can be expanded and contracted by the telescopic device. Of the stage booms constituting the telescopic boom 6 described above, the top boom 13 is an FRP lining boom.

  FIG. 2 is a diagram for explaining only the FRP lining boom 13 (top boom). The FRP lining boom 13 is obtained by lining the boom intermediate portion 14c except for the boom distal end portion 14a and the boom base end portion 14b of the steel plate boom 14 with the FRP 15 over the entire outer periphery of the cross section. The thickness of the FRP lining layer is about several millimeters, and the electric insulation of the telescopic boom 6 is achieved by this FRP lining.

  FIG. 3 is an enlarged view of the tip when the telescopic boom 6 is fully reduced. 4 is a cross-sectional view taken along arrow A in FIG. 3 and is a detailed cross-sectional view of the distal end portion 16 of the second boom 12. The surface of the steel boom 14c is lined with the FRP 15 (shaded portion) of the FRP lining boom 13 (top boom). The cross-sectional outer shape of the FRP lining boom 13 includes a side surface portion 20 that is parallel to each other and a lower surface portion 21 that is an isosceles trapezoid that protrudes downward. The isosceles trapezoid of the lower surface portion 21 is formed such that the oblique side portions 22 on both sides are long at a gentle angle, the trapezoidal top portion 23 at the center is short, and has a convex shape as a whole.

  Reference numeral 25 denotes a slide plate that slidably supports the oblique side portion 22 of the lower surface portion 21 of the FRP lining boom 13. The slide plate 25 is fixedly disposed on the inner surface of the lower surface portion 24 of the second boom distal end portion 16 with a bolt 27 via a retainer 26. As shown in FIG. 4, the width dimension of the slide plate 25 is substantially the same as the length of the oblique side portion 22.

  Since the lower surface portion 21 of the FRP lining boom 13 has a convex shape downward, when the lower surface portion 21 is slidably supported by the slide plate 25, the cross-sectional shape has high rigidity. Therefore, the surface pressure of the sliding contact surface of the slide plate 25 is made uniform. In addition, since the slide plate can have a large width as described above, the surface pressure can be lowered. Therefore, even if the FRP lining boom 13 (top boom) is expanded and contracted with respect to the outer boom (second boom 12), a temperature rise due to friction on the sliding contact surface of the slide plate 25 hardly occurs. Therefore, there is no possibility that cracks / damage due to temperature rise occur in the FRP 15 of the FRP lining boom 13.

  Reference numeral 30 denotes a slide plate that slidably supports the side surface portion 15 of the FRP lining boom 13. The slide plate 30 is fixedly arranged by bolts 27 on the inner surface of the side surface portion 32 of the second boom distal end portion 16 via the retainer 31. The position where the slide plate 30 is slidably supported is below the side surface portion 15 of the FRP lining boom 13 and in the vicinity of the bent portion 33 with the lower surface portion 21.

  As shown in FIG. 4, since the side surface portion 15 of the FRP lining boom 13 is slidably supported by the slide plate 30, the cross-sectional deformation of the side surface portion 15 can be suppressed. Accordingly, deformation of the lower surface portion 21 connected to the side surface portion 15 is also suppressed, so that the surface pressure of the sliding contact surface of the slide plate 25 that supports the lower surface portion 21 in sliding contact can be further equalized.

  In the above embodiment, the case where the FRP lining boom 13 is included as a part of the boom stage of the telescopic boom 6 has been described. However, even if the FRP boom is included instead of the FRP lining boom, the present invention is completely the same. Of course, the telescopic boom can be configured and the same effect can be obtained.

It is the aerial work vehicle X using the telescopic boom which concerns on embodiment of this invention. It is a figure which takes out and demonstrates only the FRP lining boom. It is an enlarged view of the front-end | tip part when the telescopic boom 6 is fully reduced. FIG. 4 is a cross-sectional view taken along arrow A in FIG. 3. It is sectional drawing (b) of the overlap part of the telescopic boom 4 described in patent document 1, and the partial enlarged view (a) of a slide apparatus.

6: Telescopic boom 13: FRP lining boom 14: Steel plate boom 15: FRP
20: Side surface portion 21: Lower surface portion 22: Oblique side portion 24: Outer boom tip lower surface portion 25: Slide plate 30: Slide plate 32: Outer boom tip side surface portion X: Work at height

Claims (3)

In the telescopic boom of an aerial work vehicle including an FRP boom whose entire cross section is made of FRP as a part of the boom stage of the telescopic boom, the cross-sectional outer shape of the FRP boom protrudes downward from the side surfaces parallel to each other , etc. A lower surface portion that is a trapezoidal trapezoidal shape, and the shape of the isosceles trapezoidal shape is such that the oblique sides on both sides are formed longer than the trapezoidal top of the central portion, while the inner surface of the lower surface of the tip of the outer boom into which the FRP boom is inserted A telescopic boom for an aerial work vehicle, characterized in that a slide plate that slidably supports the hypotenuse part of the isosceles trapezoid is arranged with a length substantially the same as the hypotenuse part of the equilateral trapezoid . In a telescopic boom of an aerial work vehicle including an FRP lining boom in which the surface of a steel plate boom is lined with FRP as a boom stage as a part of the telescopic boom, the cross-sectional outer shape of the FRP lining boom is parallel to the side surface portion and the lower side. A lower surface portion that is an isosceles trapezoidal shape, and the shape of the isosceles trapezoid is such that the oblique sides on both sides are formed longer than the trapezoidal top portion of the central portion, while the outer boom to which the FRP lining boom is inserted A telescopic boom for an aerial work vehicle, characterized in that a slide plate that slidably supports the hypotenuse part of the isosceles trapezoid is arranged on the inner surface of the lower surface of the tip of the isosceles trapezoid with the same length as the hypotenuse part of the isosceles trapezoid . The telescopic boom for an aerial work vehicle according to claim 1 or 2, wherein a slide plate for slidingly supporting the side surface of the FRP boom or FRP lining boom is disposed on the inner surface of the tip side surface of the outer boom. .

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