Angled Boom Comprising Variable Cross-Section for Mobile Concrete Pumps

Abstract

The invention relates to a boom arm for mobile concrete pumps and to a mobile concrete pump. The boom arm, having a first and second end, wherein at least one elbowed section, in which the main bending loads which occur during proper use act as torsional loads, is provided between the first and the second end of the boom arm, is made from a fiber composite material, wherein beyond the elbowed region the height of the boom arm in cross-section is greater than the width of the boom arm in cross-section and in the elbowed region the width of the boom arm in cross-section is greater than or equal to the height of the boom arm in cross-section. A concrete pump with a placing boom, arranged on a substructure, comprising at least two boom arms, at least one of which is designed according to the invention.

Claims

1-12. (canceled)

13. A boom arm (5) for a placing boom (2) for a concrete pump (1): said boom arm (5) made from a fiber composite material, said boom arm (5) having a first end (10) and a second end (11) and an elbowed section (12) between the first and second ends (10, 11), wherein said boom arm has a first cross-section in the elbowed section (12), said first cross-section having a width (b) greater than or equal to a height (h), and a second cross-section outside of the elbowed section (12) having a height (h) greater than a width (b).

14. The boom arm of claim 13, wherein the cross-section of the boom arm (5) transitions gradually from the first cross-section to the second cross section.

15. The boom arm of claim 13, wherein the first cross-section is based on an octagon, said octagon having p4 symmetry, said octagon having a first axis of symmetry in a direction of the height (h) of the cross section, and a second axis of symmetry in a direction of the width (b) of the cross section, the sides (15, 15) of the octagon intersecting with the first and second axis of symmetry being longer than the sides of the octagon not intersecting with the first and second axis of symmetry.

16. The boom arm of claim 13, wherein the first cross section is based on an octagon, said octagon having p4 symmetry, said octagon having a first axis of symmetry in a direction of the height (h) of the cross section, and a second axis of symmetry in a direction of the width (b) of the cross section, the sides (15) of the octagon intersecting with the first axis of symmetry being longer than the sides (15) of the octagon intersecting with the second axis of symmetry.

17. The boom arm of claim 13, wherein the second cross-section is based on an octagon, said octagon having p4 symmetry, said octagon having a first axis of symmetry in a direction of the height (h) of the cross section, and a second axis of symmetry in a direction of the width (b) of the cross section, the sides (15, 15) of the octagon intersecting with the first and second axis of symmetry being longer than the sides of the octagon not intersecting with the first and second axis of symmetry.

18. The boom arm of claim 13, wherein the second cross section is based on an octagon, said octagon having p4 symmetry, said octagon having a first axis of symmetry in a direction of the height (h) of the cross section, and a second axis of symmetry in a direction of the width (b) of the cross section, the sides (15) of the octagon intersecting with the second axis of symmetry being longer than the sides (15) of the octagon intersecting with the first axis of symmetry.

19. The boom arm of claim 13, wherein the first and second cross sections are based on an octagon, said octagon having p4 symmetry and at least some of the sides of the boom arm are curved convexly outward.

20. The boom arm of claim 13, wherein the first and second cross section are based on an octagon, said octagon having p4 symmetry, and corners formed by an intersection of the sides (15, 15, 15) of the octagon are rounded.

21. The boom arm of claim 13, wherein the boom arm (5) includes at least one through opening (18) as an articulation point, wherein outer surfaces (17) of the boom arm (5) surrounding the through opening (18) are parallel to each other.

22. The boom arm of claim 13, wherein a wall of said boom arm (5) has a first wall thickness in said elbowed section (12) and a second wall thickness outside of said elbowed section (12), said first wall thickness being equal to the second wall thickness.

23. The boom arm of claim 13, wherein a wall of said boom arm (5) has a first cross-sectional area in the elbowed section (12) and a second cross-sectional area outside of said elbowed section (12), wherein the first cross-sectional area is the same as the second cross-sectional area.

24. The boom arm of claim 13, wherein the height (h) of the first cross section is the same as the height (h) of the second cross section.

25. The boom arm of claim 13, wherein the height (h) of the boom arm (5) tapers uniformly from the first end (10) to the second end (11), including over the elbowed section (12).

26. The boom arm of claim 13, wherein said boom arm (5) is made from a continuous fiber-reinforced fiber composite material.

27. The boom arm of claim 13, wherein said first cross-section is based on an irregular octagon, and second cross-section is based on an irregular octagon.

28. A concrete pump (1) with a placing boom (2) arranged on a substructure (3) and comprising at least two boom arms (5), wherein at least one of the boom arms (5) is a boom arm of claim 13.

29. The boom arm of claim 13, wherein a wall of said boom arm (5) has a first wall thickness in said elbowed section (12) and a second wall thickness outside of said elbowed section (12), said first wall thickness being less than the second wall thickness.

30. The boom arm of claim 13, wherein the cross-sectional area occupied by the wall of the boom is constant over the length of the boom, with a wall thickness of the boom in the elbowed section (12) being less than a wall thickness of the boom outside of the elbowed section (12).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is now described by way of example with the aid of an advantageous embodiment with reference to the attached drawings, in which:

[0034] FIG. 1: shows an exemplary embodiment of a mobile concrete pump according to the invention;

[0035] FIG. 2: shows a detailed view of two boom arms of the concrete pump from FIG. 1;

[0036] FIG. 3: shows a cross-section through the elbowed boom arm from FIG. 2 in the region of the elbow; and

[0037] FIG. 4: shows a cross-section through the elbowed boom arm from FIG. 2 in the region beyond the elbow.

DETAILED DESCRIPTION

[0038] The mobile concrete pump 1 with a placing boom 2 shown in FIG. 1 is a truck-mounted concrete pump in which the placing boom 2 is fastened on a movable substructure 3. The placing boom 2 can be folded up and for this purpose comprises a plurality of boom arms 5, which can be pivoted relative to one another by hydraulic cylinders 4, inside which passes a delivery pipe 6 (only part of which is shown) for flowable concrete. Flowable concrete can be delivered with the aid of a core pump 7 arranged on the substructure 3 from the feed hopper 8 through the delivery pipe 6 to the free open end 6 of the delivery pipe 6.

[0039] Two of the boom arms 5 of the concrete pump 1 from FIG. 1 are shown individually in FIG. 2, wherein one of the two boom arms 5 is elbowed and at least the elbowed boom arm 5 is made from continuous fiber-reinforced fiber composite material. The two boom arms 5 are connected so that they can pivot relative to each other via a hinge bolt 9.

[0040] The elbowed boom arm 5 in FIG. 2 comprises an elbowed region 12 arranged between the first end 10 and the second end 11 of the boom arm 5, wherein the elbow lies in a plane parallel to the hinge bolt 9 and the pivot axis defined thereby. A cross-section through the boom arm 5 in the elbowed region is shown in FIG. 3, whilst a cross-section through the same boom arm 5 is shown in FIG. 4 but beyond the elbowed region 12.

[0041] As shown in FIGS. 3 and 4, both cross-sections are based on an octagonal base 13 with edges 15, 15, 15 shown in each case as dashed lines and corners 14 indicated by marks and, with the aid of the axes of symmetry 16 shown as dot-dash lines, in each case have a p4 symmetry. Those edges 15, 15 which are used to form the axes of symmetry 16 are here longer than the edges 15 which do not intersect any axes of symmetry 16.

[0042] As can be seen directly in FIG. 3, in the region of the elbow 12 in cross-section those edges 15 which extend in the direction of the width b are longer than those edges 15 which extend in the direction of the height h. The opposite applies beyond the elbow. As can be seen in FIG. 4, those edges 15 which extend in the direction of the height h are longer there than the edges 15 which extend in the direction of the width b.

[0043] The boom arm 5 is curved convexly outward at the edges 15, 15 of the boom arm 5 both in the region of the elbow 12 (cf FIG. 3) and beyond it (cf FIG. 4). The curvature is here configured such that the boom arm 5 has a constant height h over its whole length. The upper side of the boom arm 5, visible in FIG. 2, accordingly has no step in it. It can likewise be seen in FIG. 2 that the transition from the cross-section of the boom arm 5 in the elbowed region 12 to the cross-section beyond this region 12 is smooth such that no additional notch effect occurs as a result of the change in cross-section. Furthermore, in order to avoid other possible stress peaks, the boom arm 5 is rounded in cross-section at the corners 14 (cf FIGS. 3 and 4).

[0044] It is moreover shown in FIG. 4 that the boom arm 5 is widened outward in certain regions in such a way that two opposite parallel outer surfaces 17 result. A through opening 18 (only the axis of which is shown), for example for the passage of the hinge bolt 9 (cf FIG. 2), is provided on these parallel outer surfaces 17. Corresponding outer surfaces 17 can also be provided in regions of other through openings 18.

[0045] The boom arm 5 is manufactured in one piece from continuous fiber-reinforced fiber composite material, wherein the boom arm 5 is laminated from prefabricated mats using known methods. Over the whole length of the boom arm 5, the number of the mats for creating the structure is here constant, viewed over the cross-section. Consequently, the cross-sectional area also remains constant over the whole length of the boom arm 5. However, because the cross-section of the boom arm 5 in the region of the elbow 12 (cf FIG. 3) has a larger circumference than outside this region (cf FIG. 4), the wall thickness in the region of the elbow 12 is slightly reduced in individual part regions in order moreover to obtain this same cross-sectional area.