Concrete-pump boom-arm segment having a variable sheet-metal thickness in the longitudinal direction, and method for producing such a concrete-pump boom-arm segment

Abstract

The invention related to a concrete-pump boom-arm segment having an upper chord (33), a lower chord (34) and two lateral parts (35, 36) which connect the upper chord (33) and the lower chord (34). The boom-arm segment comprises a longitudinal connection (44) between two subregions (41, 42) of the boom-arm segment which adjoin one another in the longitudinal direction, wherein the longitudinal connection (44) extends over a chord portion (56, 66) and over a lateral part portion (53, 63). The lateral part portion (53, 63) is bent over with respect to the chord portion (56, 66) in the first subregion (41) and in the second subregion (42). The material thickness of the chord portion (56) is greater in the first subregion (41) than the material thickness of the chord portion (66) in the second subregion (42). The invention additionally relates to a method for producing such a boom-arm segment. Such a boom-arm segment is well suited for absorbing static and dynamic loads and can be produced in a cost-effective manner.

Claims

1. A concrete-pump boom-arm segment having an upper chord (33), a lower chord (34) and two side-parts (35, 36), which connect the upper chord (33) and the lower chord (34), and having a longitudinal joint (44) between two subregions (41, 42) of the boom-arm segment which adjoin one another in a longitudinal direction, wherein the longitudinal joint (44) extends over upper chord portions (56, 66) and over first side-part portions (53, 63), wherein the first side-part portions (53, 63) are bent over with respect to the upper chord portions (56, 66) in the first subregion (41) and in the second subregion (42), and wherein a material thickness of the upper chord portion (56) in the first subregion (41) is greater than a material thickness of the upper chord portion (66) in the second subregion (42), and having four reinforcing plates (46, 47), which extend across the same longitudinal joint (44), wherein two of the reinforcing plates (47) overlap with the first side-part portions (53, 63) that are bent over with respect to the upper chord portions (56, 66) and two of the reinforcing plates (46) overlap with second side-part portions (54, 64) which are bent over with respect to lower chord portions (52, 62) of the first and second subregions (41, 42), respectively, each of the four reinforcing plates (46, 47) is arranged close to a respective edge of one of the upper or lower chords (33, 34), and a distance from each reinforcing plate (46, 47) to the respective edge increases with increasing distance from the longitudinal joint.

2. The concrete-pump boom-arm segment of claim 1, wherein the material thickness in the first subregion (41) is between 2 mm and 15 mm.

3. The concrete-pump boom-arm segment of claim 1, wherein the material thickness in the second subregion is less than the material thickness in the first subregion by a value of between 0.5 mm and 4 mm.

4. The concrete-pump boom-arm segment of claim 1, wherein the upper chord portion (56) in the first subregion (41) and the upper chord portion (66) in the second subregion (42) extend in the same plane.

5. The concrete-pump boom-arm segment of claim 1, wherein the longitudinal joint (44) extends over entire widths of the upper chord portions (56, 66).

6. The concrete-pump boom-arm segment of claim 1, wherein the first side-part portions (53, 63) that are bent over with respect to the upper chord portions (56, 66) are connected to the second side-part portions (54, 64) that are bent over with respect to the lower chord portions (52, 62).

7. The concrete-pump boom-arm segment of claim 1, wherein the first side-part portions (53, 63) are connected to respective side plates (58, 59, 68), wherein the side plates (58, 59, 68) have a lower material thickness than a material thickness of the first side-part portions (53, 63).

8. The concrete-pump boom-arm segment of claim 1, wherein the boom-arm segment tapers from the first subregion (41) in the direction of the second subregion (42).

9. The concrete-pump boom-arm segment of claim 1, wherein the reinforcing plates (46, 47) taper with increasing distance from the longitudinal joint (44).

10. The concrete pump boom-arm segment of claim 1, wherein the material thickness in the first subregion (41) is between 3 mm and 10 mm.

11. The concrete pump boom-arm segment of claim 1, wherein the material thickness in the second subregion (42) is less than the material thickness in the first subregion (41) by a value of between 1 mm and 3 mm.

12. A method for producing a concrete-pump boom-arm segment, wherein the boom-arm segment comprises an upper chord (33), a lower chord (34) and two side parts (35, 36), which connect the upper chord (33) and the lower chord (34), wherein a longitudinal joint (44) is produced between a first subregion (41) of the boom-arm segment and a second subregion (42) of the boom-arm segment, which longitudinal joint (44) extends over upper chord portions (56, 66) and over first side-part portions (53, 63) of the first and second subregions (41, 42), wherein the first side-part portions (53, 63) are bent over with respect to the upper chord portions (56, 66) in the first subregion (41) and in the second subregion (42), and wherein a material thickness of the upper chord portion (56) in the first subregion (41) is greater than a material thickness of the upper chord portion (66) in the second subregion (42), and arranging four reinforcing plates (46, 47), which extend across the longitudinal joint (44), wherein two of the reinforcing plates (47) overlap with the first side-part portions (53, 63) that are bent over with respect to the upper chord portions (56, 66) and two of the reinforcing plates (46) overlap with second side part side-part portions (54, 64) which are bent over with respect to lower chord portions (52, 62) of the first and second subregions (41, 42), respectively, each of the four reinforcing plates (46, 47) is arranged close to a respective edge of one of the upper or lower chords (33, 34), and a distance from each reinforcing plate (46, 47) to the respective edge increases with increasing distance from the longitudinal joint.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described by way of example below by means of advantageous embodiments with reference to the attached drawings. In the drawings:

(2) FIG. 1: shows a concrete-pump vehicle having a boom arm in the folded state;

(3) FIG. 2: shows the concrete-pump vehicle from FIG. 1 with the boom arm unfolded;

(4) FIG. 3: shows a boom-arm segment according to the invention;

(5) FIG. 4: shows a joint between two boom-arm segments;

(6) FIG. 5: shows a detail of a boom-arm segment according to the invention;

(7) FIG. 6: shows the view according to FIG. 5 in the case of another embodiment of the invention;

(8) FIG. 7: shows a section along the line A-A through the embodiment according to FIG. 6;

(9) FIG. 8: shows a detail of a boom-arm segment in the case of an alternative embodiment of the invention;

(10) FIG. 9: shows a section along the line B-B in FIG. 8;

(11) FIG. 10: shows the view according to FIG. 9 in the case of another embodiment of the invention;

(12) FIG. 11: shows the view according to FIG. 9 in the case of another embodiment of the invention;

(13) FIG. 12: shows the view according to FIG. 8 in the case of another embodiment of the invention;

(14) FIG. 13: shows a view of a chord surface of a boom-arm segment according to the invention.

DETAILED DESCRIPTION

(15) A truck 14 shown in FIG. 1 is equipped with a concrete pump 15, which delivers liquid concrete from a pre-charging tank 16 via a delivery line 17. The delivery line 17 extends along a boom arm 18, which is rotatably mounted on a slewing ring 19. The boom arm 18 comprises three boom-arm segments 20, 21, 22, which are connected to one another in articulated fashion. Since the boom-arm segments 20, 21, 22 can be pivoted relative to one another by means of the joints, the boom arm 18 can change between a folded state (FIG. 1) and an unfolded state (FIG. 2). The delivery line 17 extends beyond the distal end of the third boom-arm segment 22, thus enabling the liquid concrete to be discharged in a region remote from the concrete pump 15.

(16) Depending on the pivoted state of the boom arm, the loads on the boom-arm segments 20, 21, 22 act in completely different directions. Moreover, the boom arm is exposed to high dynamic loads by the pulsed delivery of the liquid concrete.

(17) The pivot joints between the boom-arm segments 20, 21, 22 are configured in such a way that they allow a large pivoting angle. In the folded state, the boom-arm segments 20, 21, 22 are substantially parallel to one another and enclose a small angle between them. In the unfolded state shown in FIG. 2, the boom-arm segments 20, 21, 22 form extensions of one another.

(18) The joint design is illustrated in FIG. 4 using the example of the pivot joint between the first boom-arm segment 20 and the second boom-arm segment 21. The pivot is formed by a pivot pin 23, by means of which a proximal end of the boom-arm segment 21 is connected to a distal end of the boom-arm segment 20. A first articulated lever 24 is attached to the first boom-arm segment 20 at a point adjacent to the pivot pin 23. A second articulated lever 25 is attached to the second boom-arm segment 21 at a point adjacent to the pivot pin 23. The two articulated levers are connected to one another in articulated fashion at 26. A hydraulic cylinder 27 extends from an articulation point 28 on the first boom-arm segment 20 to the outer end of the first articulated lever 24. By means of the articulated levers 24, 25, a stroke motion of the hydraulic cylinder 27 is converted into a pivoting motion between the boom-arm segments 20, 21.

(19) A boom-arm segment 30 according to the invention, which is shown in FIG. 3, extends from a proximal end 31 to a distal end 32. The boom-arm segment 30 is designed as a box-shaped profile with an upper chord 33, a lower chord 34 and two side parts 35, 36. A pivot hole 37 is formed close to the proximal end 31. The pivot hole accommodates the pivot pin 23, which connects the boom-arm segment 30 to an adjacent boom-arm segment.

(20) Arranged next to the pivot hole 37 is a stud bolt 38, to which the articulated lever 25 is connected. A reinforcing plate 40 surrounds the pivot hole 37 and the stud bolt 38, thus enabling the particularly high forces which occur in this region to be reliably absorbed. In corresponding fashion, the boom-arm segment 30 comprises, close to its distal end, a further pivot hole 37 and a further stud bolt 38, to which an articulated lever 24 can be connected. A reinforcing plate 40 surrounds the pivot hole 37 and the stud bolt 38. Corresponding reinforcing plates 40 are formed on the opposite side part 36 of the boom-arm segment 30, which is not visible in FIG. 3.

(21) The box-shaped profile of the boom-arm segment tapers continuously from the proximal end 31 to the articulation point 28 for the hydraulic cylinder. The two side parts 35, 36 as well as the upper chord 33 and the lower chord 34 thus each approach one another as the distance from the proximal end 31 increases. The taper is still quite clear in the region of the pivot hole 37 and the continuous taper then continues to a reduced extent, such that the change in cross-section is virtually imperceptible in FIG. 3.

(22) Between the proximal end 31 and the articulation point 28, the boom-arm segment comprises two longitudinal joints 44, 45. Longitudinal joint 44 is arranged between a first subregion 41 and a second subregion 42 of the boom-arm segment, while longitudinal joint 45 is arranged between the second subregion 42 and a third subregion 43 of the boom-arm segment. The upper chord 33 and the lower chord 34 have a material thickness of 10 mm in the first subregion 41, a material thickness of 8 mm in the second subregion 42 and a material thickness of 6 mm in the third subregion 43.

(23) In the longitudinal joints 44, 45, the subregions of different material thickness butt against one another and are joined together by weld seams extending in the transverse direction. Welded-on reinforcing plates 46, 47 extend across the longitudinal joints 44, 45 and impart additional stability to the longitudinal joints 44, 45.

(24) According to FIG. 5, the box-shaped profile of the boom-arm segment in the first subregion 41 is assembled from two component profiles 51, 52. The component profiles 51, 52 are each produced from 10 mm thick steel sheet. Component profile 51 comprises two side-part portions 53, which are bent over through 90 with respect to a chord portion 56. Component profile 52 comprises two side-part portions 54, which are bent over through 90 with respect to a chord portion 57. At their end faces, the side-part portions 53, 54 are butt jointed by weld seams, with the result that a box-shaped profile of rectangular cross section is formed.

(25) Similarly, the box-shaped profile of the boom-arm segment in the second subregion 42 is assembled from two component profiles 61, 62. The component profiles 61, 62 are each produced from 8 mm thick steel sheet. Component profile 61 comprises two side-part portions 63, which are bent over through 90 with respect to a chord portion 66. Component profile 62 comprises two side-part portions 64, which are bent over through 90 with respect to a chord portion 67. At their end faces, the side-part portions 53, 54 are butt jointed by weld seams, with the result that a box-shaped profile of rectangular cross section is formed.

(26) In the region of the longitudinal joint 44, the box-shaped profile of the first subregion 41 coincides with the box-shaped profile of the second subregion 42, with the result that the two subregions 41, 42 can be joined together by a weld seam running around in the transverse direction.

(27) A reinforcing plate 46 is welded onto the side-part portions 54, 64 from the outside by means of a peripheral weld seam and extends across the longitudinal joint 44. Starting from the region of the longitudinal joint 44, the reinforcing plate 46 tapers toward its two ends. In the region of the longitudinal joint 44, the reinforcing plate 46 extends as far as the edge relative to the chord portion 57, 67. The two ends of the reinforcing plate 46 are at a distance from this edge. A reinforcing plate 47 of similar configuration is welded onto the side-part portions 53, 63 and likewise extends across the longitudinal joint 44.

(28) In the alternative embodiment shown in FIGS. 6 and 7, the side-part portions 53, 54 of component profiles 51, 52 as well as the side-part portions 63, 64 of component profiles 61, 62 are significantly shorter. Two side plates 58, 59 are welded in between the side-part portions 53, 54, said plates having a material thickness reduced by 50% compared with the component profiles 51, 52. In the first subregion 41, the side plates 58, 59 accordingly have a thickness of 5 mm. In corresponding fashion, side plates 68 are welded in between the side-part portions 63, 64 in the second subregion 42 of the boom-arm segment. The side plates 68 have a material thickness of 4 mm. The reinforcing plates 46, 47 extend beyond the edge of the side-part portions 53, 54, 63, 64 and also overlap with the side plates 58, 59, 68.

(29) In the variant shown in FIGS. 8 and 9, the two side parts of the boom-arm segment are each provided with an outward-projecting bead 70. The two chord surfaces are each provided with an inward-pointing bead 71. The beads 70, 71 impart an increased stability to the profile. The reinforcing plate 47 arranged in the upper region is thicker than the bead 70. In the region in which the reinforcing plate 47 overlaps with the bead 70, the reinforcing plate 47 has a reduced material thickness on its inside, with the result that the outside of the reinforcing plate 47 forms a flat surface. The reinforcing plate 46 arranged in the lower region is thinner than the bead 70 and ends on the sloping surface of the bead 70. In the alternative embodiment shown in FIG. 10, the lateral surfaces are each provided with two beads 72, 73 instead of the single bead 70.

(30) In the embodiment shown in FIG. 11 a reinforcing plate 74 extends over the entire width of the boom-arm segment and overlaps with the upper region of the two opposite side parts in the manner of a sleeve. FIG. 12 shows an embodiment in which the reinforcing plate 47 projects upward beyond the contour of the boom-arm segment.

(31) In FIG. 13, two reinforcing plates 75 are arranged on the chord surface and extend across the longitudinal joint 44 between the chord portions 56, 66. The reinforcing plates 75 project upward relative to the chord portions 56, 66, with the result that the extent of the boom-arm segment in the vertical direction is increased by the reinforcing plates 75.