JP2005112514A - Expansion boom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expansion boom suitably used in a working vehicle in which the lower stress σL of the boom section S is fundamentally a compression stress but the upper stress σU may also be a compression stress, equipped with a buckling strength not only in the lower part of the section but also in the upper part sufficiently. <P>SOLUTION: The first section 11 of the section of this expansion boom 10 is formed with a plate thickness t1 into approximately a U-form from the four edges due to three-time bending, five edges due to four-time bending, and seven edges due to six-time bending, or continuous bending process in many reversals, in which the edge members at the two ends are arranged parallel with each other. The second section 12 is formed with a plate thickness t2 smaller than t1 so as to have four edges due to three-time bending or five edges due to four-time bending in such an arrangement that the edge members at the two ends are parallel with each other. The ends of the first section 11 and the second section 12 are joined together to constitute the intended expansion boom. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a telescopic boom used for a work vehicle such as a mobile crane or an aerial work vehicle, and particularly to a telescopic boom having a cross-sectional shape with excellent buckling strength.

  A vertically downward load W is applied to the distal end of the telescopic boom of the work vehicle being worked by a suspended load or a work table load. The telescopic boom in operation can be thought of as a cantilever with its base end fixed to the work vehicle side and its distal end directed obliquely upward, so the vertical downward load acting on the telescopic boom tip is It can be considered to be decomposed into a load component W1 toward the base end direction of the telescopic boom central axis at the tip of the boom and a load component W2 orthogonal to the central axis of the telescopic boom.

  A compressive load F due to the load component W1 and a bending moment M (= W2 × L) about an axis perpendicular to the undulating surface act on the cross section S of the telescopic boom that is separated from the distal end of the telescopic boom by a distance L. The compressive load F generates a compressive stress σ0 over the entire cross section S, and the bending moment M generates a tensile stress σ1 at the upper end of the cross section S and a compressive stress σ2 at the lower end of the cross section S.

  The above stresses are generated in the section S in a superimposed manner, and an upper stress σU (= σ0−σ1) is generated at the upper end portion of the section S, and a lower stress σL ( = Σ0 + σ2) occurs. Generally, the stress generated in the cross section S of the telescopic boom during work is often higher in the bending stresses σ1 and σ2 due to the bending moment M than the compressive stress σ0 due to the compressive load F, so the upper stress σU becomes a tensile stress. The lower stress σL becomes a compressive stress. Therefore, the lower part of the cross section S of the telescopic boom is required to have strength against buckling.

  Conventionally, a contrivance has been proposed in which the shape of the telescopic boom cross section on the compression side (generally often on the lower side of the cross section) is strong against buckling (see, for example, Patent Document 1).

  FIG. 9 shows a cross-sectional shape of the telescopic boom described in Patent Document 1. The cross-sectional shape is formed by bending the upper section 31 having a thickness of t1 twice and the lower section 32 having a thickness of t2 bent four times and joining both ends thereof. ing.

  With respect to the lower section 32, the plate thickness t2 is made thicker than the plate thickness t1 of the upper section 31, so that the compressive stress σL generated in the lower portion of the cross section described above is reduced and the strength against buckling is increased. I am doing so.

  Further, the lower section 32 is configured such that the lower portion of the cross section is composed of the horizontal portion 36 and the inclined portions 38 on both sides thereof by setting the number of times of bending to four.

  Regarding the buckling of the lower plate in the cross section of the telescopic boom, the bent portion is a joint by forming a structure in which a short straight line portion is bent at the bottom of the cross section where compressive stress is generated as in the cross section shown in FIG. Thus, the buckling of the plate may be examined in a small section divided by the bent portion. The calculation standard of the buckling strength of the applicable board in that case is shown (for example, refer nonpatent literature 1). According to the calculation results based on the calculation criteria, it was confirmed that the basic buckling stress of the small section where the bending was performed was larger than the basic buckling stress without the bending, and the buckling strength was improved. Yes.

  The cross section of the telescopic boom shown in FIG. 10 is made strong against buckling by making the cross section of the lower section 40 into a substantially U shape (see, for example, Patent Document 2).

The substantially U-shaped cross-sectional shape of the lower section 40 is manufactured so as to be substantially U-shaped as a whole by continuing a number of bending processes. Thus, the buckling strength can also be improved by making the entire lower section substantially bent with a large radius and eliminating the straight portion.
Japanese Unexamined Patent Publication No. 2000-16673 (page 3-4, FIG. 3) EP 0 499 208B2 (page 4, figure 2) JIS B 8821 Crane steel structure calculation criteria (pages 25-26, Table 21)

  In recent years, the lower stress σL of the cross section S of the telescopic boom at the time of work is basically a compressive stress, but a work vehicle in which the upper stress σU may also become a compressive stress has been used.

  For example, by bending the mast upright on the upper surface of the base boom of the telescopic boom and connecting the tip of the telescopic boom, the tip of the mast and the base boom base end with a wire, In a mobile crane equipped with a device (called a superlift or the like) that reduces the moment and thereby improves the lifting capacity, compressive stress is generated not only in the lower part of the section of the telescopic boom but also in the upper part.

  Further, in an aerial work vehicle equipped with a telescopic boom (so-called bendable boom) having a second telescopic boom that can be raised and lowered at the tip of the first telescopic boom, depending on the posture of the second telescopic boom with respect to the first telescopic boom, Compressive stress is generated in the upper part or the lower part of the cross section of the first telescopic boom. In the first telescopic boom of the bending boom, the upper stress σU is basically a compressive stress, and the lower stress σL is a tensile stress. The relationship between the top and bottom is reversed. Therefore, the cross-sectional shape of the mobile crane or the like upside down is also used.

  However, in the cross section of the telescopic boom described in Patent Document 1 or Patent Document 2 described above, the upper portion is a straight portion having a length close to the cross-sectional width, so that the buckling strength against the generation of compressive stress is high. It was not enough.

  Therefore, the present invention is a telescopic boom suitable for use in a work vehicle in which the lower stress σL of the section S of the telescopic boom is basically compressive stress, but the upper stress σU may also be compressive stress. An object of the present invention is to provide a telescopic boom having a sufficient buckling strength not only in the lower part of the cross section but also in the upper part of the cross section.

  The telescopic boom described in claim 1 of the present application is an telescopic boom in which an intermediate boom and a top boom are telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. a first section having four sides by three times of bending and having both sides parallel to each other, and a plate thickness t2 thereof is smaller than the plate thickness t1; A second section that has four sides by a round bending process, and is constructed by joining the ends of the first section and the end of the second section. It is characterized by that.

  The telescopic boom described in claim 2 of the present application is an telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. t1, a first section having five sides by four times of bending, and both sides being parallel to each other, and a plate thickness t2 thereof is smaller than the plate thickness t1, 3 A second section that has four sides by a round bending process, and is constructed by joining the ends of the first section and the end of the second section. It is characterized by that.

  The telescopic boom described in claim 3 of the present application is an telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. a first section that is t1 and has seven sides by six times of bending and the sides of both ends are parallel to each other, and the plate thickness t2 is smaller than the plate thickness t1; A second section that has four sides by a round bending process, and is constructed by joining the ends of the first section and the end of the second section. It is characterized by that.

  The telescopic boom described in claim 4 of the present application is an telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. a first section that is substantially U-shaped as a whole by continuous bending many times, and the thickness t2 of the first section is set to be equal to the thickness t1. A second section manufactured by bending three times and having four sides, the sides of both ends being parallel to each other, and an end of the first section and an end of the second section It is characterized by joining the parts.

  The telescopic boom described in claim 5 of the present application is an telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. a first section that has four sides by three bending processes, and that both sides are parallel to each other, and a plate thickness t2 thereof is smaller than the plate thickness t1, A second section that has five sides by a round bending process, and is constructed by joining the ends of the first section and the end of the second section. It is characterized by that.

  The telescopic boom described in claim 6 of the present application is an telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. t1, a first section having five sides by four times of bending, and both sides being parallel to each other, and a plate thickness t2 thereof is smaller than the plate thickness t1, A second section that has five sides by a round bending process, and is constructed by joining the ends of the first section and the end of the second section. It is characterized by that.

  The telescopic boom described in claim 7 of the present application is an telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. a first section that is t1 and has seven sides by six bending operations, and the sides of both ends are parallel to each other, and the plate thickness t2 is smaller than the plate thickness t1; A second section that has five sides by a round bending process, and is constructed by joining the ends of the first section and the end of the second section. It is characterized by that.

  The telescopic boom described in claim 8 of the present application is an telescopic boom in which an intermediate boom and a top boom are telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom has a plate thickness. a first section that is substantially U-shaped as a whole by continuous bending many times, and the thickness t2 of the first section is set to be equal to the thickness t1. And a second section which has five sides by four times of bending and is manufactured so that both sides are parallel to each other. The end of the first section and the end of the second section It is characterized by joining the parts.

  In the telescopic boom according to any one of claims 1 to 4, the first section has four sides by three times bending, four sides by four times bending, seven sides by six times bending, or a plurality of times of bending. Since it has a substantially U shape by being continuous and is manufactured so that the sides of both ends are parallel to each other, it has a sufficient buckling strength against the compressive stress normally generated in the first section.

  Furthermore, in the telescopic boom described in claims 1 to 4, the second section has four sides by three times of bending, and the sides are manufactured so that the sides at both ends are parallel to each other. It can have sufficient buckling strength against compressive stress that may occur in the two sections.

  Further, since the thickness of the second section is made thinner than the thickness of the first section, the stress level can be made uniform and the weight of the entire telescopic boom can be reduced.

  In the telescopic boom according to any one of claims 5 to 8, the first section has four sides by three times of bending, five sides by four times of bending, seven sides by six times of bending, or a plurality of times of bending. Since it has a substantially U shape by being continuous and is manufactured so that the sides of both ends are parallel to each other, it has a sufficient buckling strength against the compressive stress normally generated in the first section.

  Furthermore, in the telescopic boom described in claims 5 to 8, the second section has five sides by four times of bending, and is manufactured so that the sides at both ends are parallel to each other. It can have sufficient buckling strength against compressive stress that may occur in the two sections.

  Similarly, since the plate thickness of the second section is made thinner than the plate thickness of the first section, the stress level can be made uniform and the weight of the entire telescopic boom can be reduced.

  In the telescopic boom described in claims 1 to 8 of the present application, the buckling strength is improved by adding a bending process, so the weight is higher than the method of improving the buckling strength by adding a reinforcing material. This is advantageous in that it does not increase.

  1 to 8 show a cross-sectional shape of a telescopic boom that shows the best mode for carrying out the invention. The telescopic boom is configured such that an intermediate boom such as a second boom and a third boom and a top boom are fitted in the base boom, and each of them can be telescopic.

  The cross sections of the booms constituting the telescopic boom have basically the same cross sectional shape from the base boom to the top boom, and in many cases, cross sections having different dimensions and proportions of the respective parts are employed. However, the present invention is not limited to this, and the cross-sectional shapes shown in FIGS. 1 to 8 can be employed only for a specific boom stage constituting the telescopic boom.

  The cross-sectional shape of the telescopic boom of the present invention is that the first section has a thickness of t1, four sides by three times bending, four sides by four times bending, seven sides by six times bending, or many times. It is manufactured so that it has a substantially U shape by continuing the bending process, and the sides at both ends are parallel to each other.

  Further, the second section has a plate thickness t2 smaller than the plate thickness t1, and has four sides by three times bending, or five sides by four times bending, and both sides are parallel to each other. Produce to be. And the edge part of a 1st section and the edge part of a 2nd section are joined, and an expansion-contraction boom is comprised. The joining is performed by welding. As a specific welding method, butt welding, backing + butt welding, lap fillet welding, or the like is adopted.

  In FIG. 1, the cross-sectional shape of the telescopic boom 10 which concerns on Example 1 of this invention is shown. The telescopic boom 2 according to the first embodiment corresponds to the telescopic boom according to the first aspect of the present invention. Reference numeral 11 denotes a first section that has a plate thickness of t1, has four sides by three times of bending, and is manufactured so that both sides are parallel to each other. Reference numeral 12 denotes a second section having a plate thickness t2 smaller than the plate thickness t1, having four sides by three bending processes, and having both sides parallel to each other. The telescopic boom 10 is configured by joining the end of the first section 11 and the end 12 of the second section.

  In FIG. 2, the cross-sectional shape of the telescopic boom 20 which concerns on Example 2 of this invention is shown. The telescopic boom according to the second embodiment corresponds to the telescopic boom according to the invention described in claim 2. Reference numeral 21 denotes a first section that has a plate thickness of t1, has five sides by four bending processes, and is formed so that the sides at both ends are parallel to each other. Reference numeral 22 denotes a second section having a plate thickness t2 smaller than the plate thickness t1, having four sides by three bending processes, and having both sides parallel to each other. The telescopic boom 20 is configured by joining the end of the first section 21 and the end of the second section 22.

  In FIG. 3, the cross-sectional shape of the telescopic boom 30 which concerns on Example 3 of this invention is shown. The telescopic boom according to the third embodiment corresponds to the telescopic boom according to the invention described in claim 3. Reference numeral 31 denotes a first section that has a plate thickness of t1, has seven sides by six bending processes, and has both sides parallel to each other. Reference numeral 32 denotes a second section that has a plate thickness t2 smaller than the plate thickness t1, has four sides by three bending processes, and has both sides parallel to each other. The telescopic boom 30 is configured by joining the end of the first section 31 and the end of the second section 32.

  In FIG. 4, the cross-sectional shape of the telescopic boom 40 which concerns on Example 4 of this invention is shown. The telescopic boom according to the fourth embodiment corresponds to the telescopic boom according to the invention described in claim 4. Reference numeral 41 denotes a first section which has a plate thickness of t1 and is substantially U-shaped as a whole by continuing a large number of bending processes, and the sides at both ends are parallel to each other. Reference numeral 42 denotes a second section that has a plate thickness t2 smaller than the plate thickness t1, has four sides by three bending processes, and has both sides parallel to each other. The telescopic boom 40 is configured by joining the end of the first section 41 and the end of the second section 42.

  In FIG. 5, the cross-sectional shape of the telescopic boom 50 which concerns on Example 5 of this invention is shown. The telescopic boom according to the fifth embodiment corresponds to the telescopic boom according to the invention described in claim 5. Reference numeral 51 denotes a first section that has a plate thickness of t1, has four sides by three bending processes, and is formed so that the sides at both ends are parallel to each other. Reference numeral 52 denotes a second section having a plate thickness t2 smaller than the plate thickness t1, having five sides by four times of bending, and having both sides parallel to each other. The telescopic boom 50 is configured by joining the end of the first section 51 and the end of the second section 52.

  In FIG. 6, the cross-sectional shape of the telescopic boom 60 which concerns on Example 6 of this invention is shown. The telescopic boom according to the sixth embodiment corresponds to the telescopic boom according to the invention described in claim 6. Reference numeral 61 denotes a first section that has a plate thickness of t1, has five sides by four bending processes, and is formed so that the sides at both ends are parallel to each other. Reference numeral 62 denotes a second section that has a plate thickness t2 smaller than the plate thickness t1, has five sides by four bending processes, and has both sides parallel to each other. The telescopic boom 60 is configured by joining the end of the first section 61 and the end of the second section 62.

  In FIG. 7, the cross-sectional shape of the expansion-contraction boom 70 which concerns on Example 7 of this invention is shown. The telescopic boom according to the seventh embodiment corresponds to the telescopic boom according to the seventh aspect of the present invention. Reference numeral 71 denotes a first section that has a plate thickness of t1, has seven sides by six bending processes, and is formed so that the sides at both ends are parallel to each other. Reference numeral 72 denotes a second section that has a plate thickness t2 smaller than the plate thickness t1, has five sides by four bending processes, and has both sides parallel to each other. The telescopic boom 70 is configured by joining the end of the first section 71 and the end of the second section 72.

  In FIG. 8, the cross-sectional shape of the telescopic boom 80 which concerns on Example 8 of this invention is shown. The telescopic boom according to the eighth embodiment corresponds to the telescopic boom according to the invention described in claim 8. Reference numeral 81 denotes a first section which has a plate thickness of t1 and has a substantially U-shape as a whole by continuing a large number of bending processes, so that both sides are parallel to each other. Reference numeral 82 denotes a second section that has a plate thickness t2 smaller than the plate thickness t1, has five sides by four bending processes, and has both sides parallel to each other. The telescopic boom 80 is configured by joining the end of the first section 81 and the end of the second section 82.

2 is a cross section of the telescopic boom according to the first embodiment. It is a cross section of the telescopic boom which concerns on Example 2. FIG. It is a cross section of the telescopic boom which concerns on Example 3. FIG. It is a cross section of the telescopic boom which concerns on Example 4. FIG. It is a cross section of the telescopic boom which concerns on Example 5. FIG. 10 is a cross section of a telescopic boom according to Example 6. 10 is a cross section of a telescopic boom according to a seventh embodiment. 10 is a cross section of a telescopic boom according to Example 8. It is a cross section of the telescopic boom described in patent document 1. It is a cross section of the telescopic boom described in patent document 2. FIG.

Explanation of symbols

10 is a telescopic boom, 11 is a first section, 12 is a second section, 20 is a telescopic boom, 21 is a first section, 22 is a second section, 30 is a telescopic boom, 31 is a first section, and 32 is a second section , 40 is a telescopic boom, 41 is a first section, 42 is a second section, 50 is a telescopic boom, 51 is a first section, 52 is a second section, 60 is a telescopic boom, 61 is a first section, and 62 is a second section. 70, telescopic boom, 71 first section, 72 second section, 80 telescopic boom, 81 first section, 82 second section,

Claims (8)

A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1, which has four sides by bending three times, and which is manufactured so that the sides at both ends are parallel to each other;
A first section having a plate thickness t2 smaller than the plate thickness t1, having four sides by three bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined. A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1, which has five sides by four times of bending, and is manufactured so that the sides on both sides are parallel to each other;
A first section having a plate thickness t2 smaller than the plate thickness t1, having four sides by three bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined. A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1, which has seven sides by six bending operations, and which is manufactured so that both sides are parallel to each other;
A first section having a plate thickness t2 smaller than the plate thickness t1, having four sides by three bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined. A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1 and which is substantially U-shaped as a whole by continuing a number of bending processes, and the sides of both ends are parallel to each other;
A first section having a plate thickness t2 smaller than the plate thickness t1, having four sides by three bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined. A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1, which has four sides by bending three times, and which is manufactured so that the sides at both ends are parallel to each other;
A first section having a thickness t2 smaller than the thickness t1, having five sides by four bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined. A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1, which has five sides by four times of bending, and is manufactured so that the sides on both sides are parallel to each other;
A first section having a thickness t2 smaller than the thickness t1, having five sides by four bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined. A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1, which has seven sides by six bending operations, and which is manufactured so that both sides are parallel to each other;
A first section having a thickness t2 smaller than the thickness t1, having five sides by four bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined. A telescopic boom in which an intermediate boom and a top boom are respectively telescopically inserted into a base boom, and the cross-sectional shape of the telescopic boom is
A first section whose thickness is t1 and which is substantially U-shaped as a whole by continuing a number of bending processes, and the sides of both ends are parallel to each other;
A first section having a thickness t2 smaller than the thickness t1, having five sides by four bending processes, and having both sides parallel to each other. A telescopic boom, characterized in that the end of the section and the end of the second section are joined.

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