JP5902882B2 - Telescopic jib for cranes, especially for mobile cranes - Google Patents

Description

  The present invention relates to a telescopic jib for a crane, particularly a mobile crane. The telescopic jib includes a main jib, which has a base box and a plurality of telescopic jib portions that can be nested and advanced therein. The foundation box and the stretchable jib portion are made of a deformed material, and the foundation box and the stretchable jib portion are made of a plate material. Each of the foundation box and the telescopic jib portion has an upper half shell and a lower half shell, and the opposing legs of the upper half shell and the lower half shell are: Welded together.

  Such a stretchable jib is known from Patent Document 1 or Patent Document 2.

  In order to optimize weight and accept different loads, the thickness of the upper shell is generally thinner than the thickness of the lower shell.

  In this context, it is often mentioned about the standard wall thickness, but this is because there is a slight thickness variation that is often unavoidable that often occurs when rolling a sheet, both laterally and longitudinally. Means not considered.

  The wall thickness design for the area of maximum load will essentially determine the jib weight. In that case, as a whole, naturally the total weight also depends on the jib length sought and thus the required number of telescopic jib parts. Limitations on maximum changeable jib weight, jib length and changeable jib height are revealed by road traffic permit regulations that specify maximum axle load, traffic height and maximum length.

  For this reason, efforts have been made to minimize the weight of the jib and to achieve high profile rigidity within the available structural space.

  In this regard, Patent Document 1 proposes that the lower shell is manufactured in a sandwich manner, and more specifically, the lower shell is divided into two relatively thin plates separated from each other, and their It is produced from a filler provided in between to completely or partially fill the void.

  Apart from that, it is known to produce a plate with a so-called standard wall thickness and then locally weld a plate piece or sheet to this plate. However, a disadvantage of this technique is that material changes or structural changes can occur in the area of the weld, and these changes adversely affect the strength as a whole.

  Furthermore, welding distortion occurs due to stress entering during welding. This weld distortion must be removed again by subsequent straightening of the box. This straightening process itself generates stress and can cause dimensional instability. As a result, the non-uniform contact pattern and wear pattern are surfaced during the subsequent assembly process or during operation after assembly.

German Patent Invention No. 199488830 Specification German Patent Application Publication No. 19711975

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is a crane that satisfies the requirements posed for a telescopic jib that is relatively simple to manufacture, that is more dimensionally stable, less distorted, and that requires high load capacity while reducing weight It is to provide a telescopic jib for use.

  This problem is solved by the telescopic jib for the crane of the present invention, particularly for a mobile crane. The telescopic jib of the present invention includes a main jib, and the main jib includes one foundation box and a plurality of telescopic jib portions that can be nested and advanced therein, and the foundation box and the telescopic jib. The jib portion is made of a profile material, and the foundation box and the stretchable jib portion are made of a plate material, and the foundation box and the stretchable jib portion are respectively composed of an upper half shell and a lower half shell. And the opposite half of the upper half shell and the lower half shell are welded to each other, and the base material for the base box and the telescopic jib portion is manufactured by rolling. It is formed from locally strengthened plate material.

  Consciously creating locally strengthened parts during rolling when manufacturing intermediate products has the advantage that the material structure does not change, i.e. from homogeneous materials with compensated stress patterns. Can be generated. Thus, it is no longer necessary to calculate the wall thickness required locally each time, for example taking into account material weakening and additional weight gain caused by welding of the reinforcement. On the other hand, the dependency between load capacity and wall thickness can be realized more easily, and on the other hand, weight can be saved as a whole.

  Another advantage is that the corresponding intermediate product (plate) is provided as a finished product by the manufacturer, saving the additional effort of welding the unique profile edges and locally strengthened parts. be able to.

It is a schematic cross-sectional view of the lower shell.

  In the following, the invention will be described, with reference to the exemplary embodiments shown and the half-shells formed correspondingly.

  As is apparent from the figure, the shells have different wall thicknesses. Here, the reinforcing portions 1 and 5 are formed in the end region of the leg portion, that is, the so-called abdominal region. The reinforcing portion 3 is formed in a top region, that is, a so-called upper chordal region and a lower chordal region. The intermediate region has a normal wall thickness, that is, a standard wall thickness.

  The drawing shows a typical cross-sectional shape. However, the present invention is not limited to this, and can be similarly used when the shell has a rectangular cross section.

  As already mentioned at the beginning, different plate thicknesses are generated mainly by cold rolling pre-manufactured plate. The rolls are separated and approached to correspond to the desired wall thickness. In practice, this plate is called tailored rolled blank (TRB). It is also possible to utilize a grooved roll when producing locally strengthened plate material.

Claims (1)

A telescopic jib for a crane, in particular a mobile crane, the telescopic jib comprising a main jib, the main jib being capable of entering and advancing in a nested manner within one foundation box and in the foundation box A plurality of stretchable jib portions, wherein the foundation box and the stretchable jib portion are made of a deformed material, and the foundation box and the stretchable jib portion are made of an intermediate product or a plate material, the foundation box and the Each of the telescopic jib portions has an upper half shell and a lower half shell, and the opposing leg portions of the upper half shell and the lower half shell are welded to each other.
The intermediate product or the plate material for the base box and the stretchable jib portion is formed from a plate material locally strengthened during production by rolling,
The upper half shell and the lower half shell are each U-shaped, and a curved portion connected to the leg portion is configured to continue to a central top portion,
A locally strengthened portion includes a distal end portion of the leg that extends linearly so as to be continuous with a curved portion of each of the upper half shell and the lower half shell; and A telescopic jib disposed on the top half of each of the upper half shell and the lower half shell extending linearly .

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