WO2019043291A1

WO2019043291A1 - Horizontal main girder of crane

Info

Publication number: WO2019043291A1
Application number: PCT/FI2018/050608
Authority: WO
Inventors: Juha PEIPPO
Original assignee: Konecranes Global Corporation
Priority date: 2017-08-29
Filing date: 2018-08-28
Publication date: 2019-03-07
Also published as: FI20175766A1

Abstract

The invention relates to a horizontal main girder of a crane, which comprises a crane beam (1) articulatedly supported at both its ends. Means (2) have been ar-ranged on the crane beam (1) to bring about a counter moment for the loads the 5 crane beam (1) is subjected to during its use.

Description

Horizontal main girder of crane

Background of the invention

The invention relates to a horizontal main girder of a crane, which comprises a crane beam articulatedly supported at both its ends. Supporting ar- ticulatedly typically refers to a combination of a crane beam and rail wheel, whereby the "articulations" are formed of rail wheels at the ends of the crane beam.

The profile of the crane beam may be an I profile or a more expensive closed profile. Loads are directed at a crane beam, which cause shifts and stress on the beam. The problem is the large size or small span of the crane beam to keep the shifts and stress of the crane beam small enough.

Summary of the invention

An object of the invention is to avoid the above disadvantages. This object is achieved with the main girder according to the invention, which is charac- terised in that means for creating a counter moment have been arranged in the crane beam for the loads directed at the crane beam during its use.

Preferred embodiments of the invention are disclosed in the dependent claims.

In the most advantageous implementation, the means for creating a counter moment comprise at least one pulling element arranged under the crane beam, the length of which increases, in other words, the pulling element extends as the crane beam bends downward. So, this pulling element is installed on the side of the crane beam acting as the main girder, which bends convex due to loads running along the crane beam. A change in the length causes pulling on element in question. The pulling force thus generated creates, for its part, a counter moment whereby the load situation on the crane beam turns more advantageous.

The invention is therefore based on utilising support moment for load bearing of the crane beam.

By means of the invention, the shift and maximum moment of the crane beam decrease when it is subjected to a load, as a result of which the profile size may be reduced, or if the profile size is kept unchanged, the span may be made longer, or the cheaper I profile may be selected as the profile instead of the more expensive closed profile. As the maximum moment of the crane beam is reduced, the extension joints possible made on it will also be easier to implement. Likewise, the scope of use of an open I profile is broadened at localities where losing stability when the crane beam swings has been a limiting factor.

List of figures

The invention will now be described in more detail in connection with preferred embodiments and with reference to the accompanying drawings, in which

Figure 1 shows loading on a conventional main girder of a crane;

Figure 2 shows loading on an inventive main girder of a crane; Figure 3 shows a comparison on loading between the conventional and inventive main girder;

Figures 4 to 10 show preferred embodiments of the main girder according to the invention.

Detailed description of the invention

Referring to Figure 1, there is shown a schematic view of a horizontal main girder of a crane, which comprises a crane beam 1, articulatedly supported (fulcrums or articulation lines 0) at both of its ends, the span of which is L. The fulcrums or articulation lines 0 may be formed on a rail arranged at contact points of rail wheels at the ends of the crane beam 1 (these are not shown). The load that the crane beam 1 is subjected to consists of the weight Q of the crane beam 1 itself as well as the force F, which is caused by a trolley and the load it is carrying (now shown), moving along the crane beam 1 This loading causes shifts and stress on the crane beam 1. The stress may be either compression stress or tensile stress. The magnitude of the stress depends on the moment M caused by the load, computational variable I of the cross section and edge distance. For shifts, coefficient of elasticity E is included. The dotted line in Figure 1 depicts the shift state of the crane beam 1.

The maximum moment for the structure of Figure 1 may be calculated with the equation:

ΜΜΑΧ,Α = F X L/4 + Q X L/8, and the maximum shift with the equation:

VMAX.A = F X L³/(48 x E x I) + 5 x Q x L³/(384 x E x I) With reference to Figure 2, the inventive pulling element 2 has been installed on the crane beam 1 of Figure 1, under it and at a distance A by means of rigid suspension, in the form of a simplified schematic presentation, the length of which increases along with the bending of the crane beam 1. So, this utilises the twist of the ends of the crane beam 1, caused by the load on the crane beam 1. A change in the length of the pulling element 2 causes pulling on the pulling element 2. The pulling force generated in turn brings about a counter moment M₂, the magnitude of which has been created by the pulling force multiplied by the distance A. This counter moment M₂ compensates the load situation of the crane beam 1 and reduces its bending.

By setting M₂ so high that the magnitude of the differential of the bending line becomes 0, a situation is achieved where it is assumed that the crane beam 1 has been firmly supported at both its ends. In such a case, the maximum moment may be calculated with the equation:

ΜΜΑΧ,Β = F X L/8 + Q X L/24, and the maximum shift with the equation: VMAX.A = F X L³/(192 x E x I) + Q x L³/(384 x E x I)

By examining the equations in the above, it is detected that the support moment M₂ significantly reduces both the maximum moment and shift of the crane beam 1.

Figure 3 shows by way of example the effect of the support moment M₂ on both the moment and shift ratio. The calculation varies the ratio between the weight Q of the crane beam 1 and payload F. Here, too, it is detected that the support moment M₂ significantly reduces both the maximum moment and shift. This allows selecting a smaller cross-section for the crane beam 1 or a longer length of the crane beam 1 with the same profile size without meeting the stress or shift limit. In crane structures, the shift limit in the vertical plane typically varies between L/350 and L/1000.

With reference to a simplified practical implementation of the invention, shown in Figure 4, under the crane beam 1, supported from below to ful- crums or articulation lines 0, at a distance from the crane beam 1 symmetrically in relation to the vertical symmetry plane in the direction of the longitudinal axis of the crane beam 1, there are arranged two pulling elements 2 in the direction of the longitudinal axis of the crane beam 1, which are at both ends connected to each other with connecting rods 3 and to the crane beam 1 with two support poles 4 and 5, forming a triangular support at any one time, whereby fastening points C of the support poles 4 and 5 on the crane beam 1 form the corner points of a rectangular connecting pattern. The support poles 4 and 5 constituting said triangular support comprise at each particular time a substantially vertical support pole 4, and a support pole 5 obliquely directed towards the end of the crane beam 1.

When the crane beam 1 according to Figure 4 is subjected to a load from above, so by a trolley and the load it is supporting, for example, the crane beam 1 bends downward whereby the connecting points P between the pulling elements 2 and support poles 4 and 5 try to shift towards the ends of the crane beam 1. In such a case, a stretch is created on the pulling elements 2, causing a pulling force on the pulling elements 2. A counterforce of this pulling force is es- tablished at connecting points P, which bring about the counter moment M₂,described above, on the crane beam 1.

Figure 5 shows a simplified practical implementation of the invention, in which, just like in the implementation of Figure 4, under the crane beam 1, at a distance from the crane beam 1 symmetrically in relation to the vertical sym- metry plane in the direction of the longitudinal axis of the crane beam 1, there are arranged two pulling elements 2 in the direction of the longitudinal axis of the crane beam 1, which are at both ends connected to each other with connecting rods 3 and to the crane beam 1 with two support poles 4 and 5, forming a triangular support at any one time. The difference to the implementation of Figure 4 is that now the fastening points C of the support rods 4 and 5 on the crane beam 1 are located in the same line on said vertical symmetry plane. In this implementation, too, the triangular support comprises a support pole 4 on the substantially transverse vertical plane in relation to the crane beam 1, and a support pole 5 obliquely directed towards the end of the crane beam 1.

The behaviour under load of the implementation of Figure 5 is essentially the same as in the case of Figure 4.

Figure 6 shows a simplified practical implementation of the invention in which under the crane beam 1 at a distance from the crane beam 1, on the vertical symmetry plane of the crane beam 1 there is arranged just one pulling ele- ment 2 in the direction of the longitudinal axis of the crane beam 1, which is at both ends connected to the crane beam with three support poles 4, 5, whereby the fastening points C of the support poles 4 and 5 on the crane beam 1 form the corner points of a triangular connecting pattern, out of which two are located on a horizontal line transverse in relation to the crane beam . In such a case, the support poles 4 associated with the corner points on the horizontal line transverse in relation to the crane beam 1 are located on a substantially transverse vertical plane in relation to the crane beam 1, and the support pole 5 associated with the third corner point is directed obliquely towards the end of the crane beam 1.

The behaviour under load of the implementation of Figure 6 is essentially the same as that in the implementations shown in Figure 4 and 5.

The goal is to make the joints between the pulling elements 2, support poles 4 and 5, as well as crane beam 1 with an articulation. If need be, reinforcements are arranged on the crane beam 1 in the area of the fastening points of support poles 4 and 5. This may be necessary in particular when an I beam is used, whereby the reinforcements are placed between the top and bottom flanges of the I beam. The crane beam 1 in the figures of the drawings is only shown as a schematic example, and so the webs of the I beam shown in them may be thicker and the flanges shorter.

The shape of the pulling elements 2 may be free, and ropes, belt, chain, and various profiles may act as the pulling elements 2. The aim is the install the pulling elements 2 without a clearance, and prestressing may be arranged on them. The pulling elements 2 may also consist of a plurality of elements.

Figures 7 A and 7B show an implementation of the invention, in which under the crane beam 1, at a distance from the crane beam 1 symmetrically in relation to the vertical symmetry plane in the direction of the longitudinal axis of the crane beam 1, there are arranged two pulling elements 2 in the direction of the longitudinal axis of the crane beam 1, which are at both ends connected the crane beam 1 to the both sides of the crane beam 1 and by support levers 40 extending above it which at both ends of the crane beam 1 are connected to each other with a connecting rod 41, supported against the bottom surface of the crane beam 1, and a connecting rod 42, supported against the top surface of the crane beam 1. The support levers 40 are directed obliquely towards the end in question at each particular time of the crane beam 1, and their position on the crane beam 1 is implemented by means of friction or fastening between the connecting rods 41, 42 and the crane beam 1. Figure 7 A is, like in the preceding figures, a side view of the crane beam 1, and Figure 7B is a cross section of the crane beam 1. The implementation of Figures 7 A and 7B also seek to affect the behaviour of the crane beam 1 under load, in the same manner as with the implementations of Figures 4 to 6. The moment M₂ supporting the crane beam 1 is established by means of the pulling elements 2, support levers 40, and connecting rods 41 and 42.

Figure 8 shows an implementation of the invention, in which under the crane beam 1, at a distance from the crane beam 1 symmetrically in relation to the vertical symmetry plane in the direction of the longitudinal axis of the crane beam 1, there is arranged at least one pulling element 2 in the direction of the longitudinal axis of the crane beam 1, which is at both ends connected to a rigid protrusion 6 extending downward from the crane beam 1 at any one time. When the crane beam 1 is subjected to a load, it twists around the support points 0, whereby the connecting points P' of the pulling element 2 and protrusions seek to shift towards the ends of the crane beam 1. In this case, the stretch of the pulling element 2 brings about, by means of the pulling element 2, a counter moment M₂ on the crane beam 1.

Figure 9 suggests means without dedicated pulling elements to bring about the counter moment, whereby these means comprise, at both ends of the crane beam 1, two adjacent support points Si and S₂ at a predetermined distance from each other. As the crane beam 1 is bending downward, the support reaction forces F₂ at the inner supports points S₂ are larger than the support reaction forces Fi at the outer support points Si, whereby the force couple formed by these forces causes the counter moment M₂ on the crane beam 1.

Figure 10 suggests a second implementation for the means to bring about a counter moment without separate pulling elements, whereby these means comprise, at both ends of the crane beam 1, two support points Si' and S₂', the first of which, so the support point Si' is the support point receiving the vertical forces of the crane beam 1, and the second one of which, so the support point S₂', is a support point preventing the horizontal shift. As the support beam 1 is subjected to a load, these bring about a force component which causes a counter moment M₂ on the crane beam 1.

The above description of the invention is only intended to illustrate the basic idea of the invention. A person skilled in the art may, however, implement the details of the invention within the scope of the attached claims.

Claims

1. A horizontal main girder of a crane, which comprises a crane beam (1) articulatedly supported at both ends, characterised in that, on the crane beam (1), means (2; Si, S₂; Si', S₂') have been arranged to cause a counter moment (M₂) for loads the crane beam (1) is subjected to during its use.

2. A main girder as claimed in claim 1, characterised in that the means for creating a counter moment comprise at least one pulling element (2) arranged under the crane beam (1), the length of which increases as the crane beam (1) bends downward.

3. A main girder as claimed in claim 2, characterised in that, under the crane beam (1), at a distance from the crane beam (1) symmetrically in relation to the vertical symmetry plane in the direction of the longitudinal axis of the crane beam (1), there are arranged two pulling elements (2) in the direction of the longitudinal axis of the crane beam (1), which are at both ends connected to each other with connecting rods (3) and to the crane beam (1) with two support poles (4, 5) , forming a triangular support at any one time, whereby fastening points (C) of the support poles (4, 5) on the crane beam (1) form the corner points of a rectangular connecting pattern.

4. A main girder as claimed in claim 3, characterised in that the triangular support comprises a substantially vertical support pole (4), and a support pole (5) obliquely directed towards the end of the crane beam (1).

5. A main girder as claimed in claim 2, characterised in that, under the crane beam (1), at a distance from the crane beam (1) symmetrically in relation to the vertical symmetry plane in the direction of the longitudinal axis of the crane beam (1), there are arranged two pulling elements (2) in the direction of the longitudinal axis of the crane beam (1), which are at both ends connected to each other with connecting rods (3) and to the crane beam (1) with two support poles (4, 5), forming a triangular support at any one time, whereby the fastening points (C) of the support poles (4, 5) on the crane beam (1) are located in the same line on said vertical symmetry plane.

6. A main girder as claimed in claim 5, characterised in that the triangular support comprises a support pole (4) on a substantially transverse vertical plane in relation to the crane beam (1), and a support pole (5) obliquely directed towards the end of the crane beam (1).

7. A main girder as claimed in claim 2, characterised in that under the a crane beam (1) at a distance from the crane beam (1), on the vertical symmetry plane of the crane beam (1), there is arranged one pulling element (2) in the direction of the longitudinal axis of the crane beam (1), which is at both ends connected to the crane beam (1) with three support poles (4, 5), whereby the fastening points (C) of the support poles (4, 5) on the crane beam (1) form the corner points of a triangular connecting pattern, out of which two are located on a horizontal line transverse in relation to the crane beam (1).

8. A main girder as claimed in claim 7, characterised in that the support poles (4) associated with the corner points on the horizontal line transverse in relation to the crane beam (1) are located on a substantially transverse vertical plane in relation to the crane beam (1), and the support pole (5) associated with the third corner point is directed obliquely towards the end of the crane beam.

9. A main girder as claimed in claim 2, characterised in that, under the crane beam (1), at a distance from the crane beam (1) symmetrically in relation to the vertical symmetry plane in the direction of the longitudinal axis of the crane beam (1), there are arranged two pulling elements (2) in the direction of the longitudinal axis of the crane beam (1), which are at both ends connected the crane beam (1) to both sides of the crane beam (1) and by support levers (40) extending above it which at both ends of the crane beam (1) are connected to each other with a connecting rod (41), supported against the bottom surface of the crane beam (1), and a connecting rod (42), supported against the top surface of the crane beam (1).

10. A main girder as claimed in claim 9, characterised in that the supports levers (40) are directed obliquely towards the end in question at any one time of the crane beam (1).

11. A main girder as claimed in claim 10, characterised in that the position of the support levers (40) on the crane beam (1) is implemented by means of a friction between the connecting rods (41, 42) and crane beam (1).

12. A main girder as claimed in claim 10, characterised in that the position of the support levers (40) on the crane beam (1) is implemented by means of fastening the connecting rods (41, 42) to the crane beam (1).

13. A main girder as claimed in claim 2, characterised in that, under a crane beam (1), at a distance from the crane beam (1) symmetrically in relation to the vertical symmetry plane in the direction of the longitudinal axis of the crane beam (1), there is arranged at least one pulling element (2) in the direction of the longitudinal axis of the crane beam (1), which is at both ends connect- ed to a rigid protrusion (6) extending downward from the crane beam (1) at any one time.

14. A main girder as claimed in claim 1, characterised in that the means for creating a counter moment comprise, at both ends of the crane beam (1), two parallel support points (Si, S₂) in the longitudinal direction of the crane beam.

15. A main girder as claimed in claim 1, characterised in that the means to bring about a counter moment comprise, at both ends of the crane beam (1), two support points (Si', S₂'), the first of which (Si') is the support point receiving the vertical forces of the crane beam, and the second one of which (S₂'), is a support point preventing the horizontal shift.

16. A main girder as claimed in claim 1, characterised in that the main girder (1) comprises an I beam.

17. A main girder as claimed in claim 1, characterised in that the main girder (1) comprises a closed beam.