Spreader bar for precisely positioning a load.

Abstract

The invention relates to a system 1 for lifting a part 2, comprising a spreader bar 3 and slinging means 4, the latter comprising at least suspension lines 20 for suspending the part from the spreader bar, at least one adjusting line 30 diagonal to the suspension lines, and tensioning means 36 for adjusting the length of the line. Figure 1 for the abstract

Description

Title of the invention: Lifting beam for positioning a load with precision.

[0001] The invention lies in the field of lifting devices, in particular lifting beams.

[0002] Some parts to be lifted must be positioned with great precision. In particular, it is important to be able to guarantee the verticality of the part to be lifted in order to slide it inside a second part already in place, without damaging either of these parts. However, lifting systems, like the parts to be lifted, have manufacturing tolerances, so that the position of the center of gravity cannot be anticipated and the lifted part takes a position inclined relative to the vertical.

[0003] An aim of the invention is to propose a lifting system which makes it possible to guarantee precision in the vertical positioning of the lifted part.

[0004] According to the invention, a lifting system according to the invention for lifting a part comprises a lifting beam and slinging means which comprise: - at least two lines, preferably four lines, to suspend the part from the lifting beam, the two lines together defining an adjustment plane, - at least one diagonal adjustment line to the hangers in the adjustment plane; and, - tensioning means for the line.

[0005] The spreader bar may comprise a longitudinal beam and two balance beams transverse to the beam, each articulated at a longitudinal end of this beam, the slinging means comprising four hangers each suspended at a respective end of a respective balance beam, these hangers together forming substantially a parallelepiped and defining, two by two, two diagonal adjustment planes of the parallelepiped.

[0006] Advantageously, in each adjustment plane the two slings which define this plane also define a parallelogram of which at least one line forms a diagonal.

[0007] Embodiments and variants will be described below, by way of non-limiting examples, with reference to the appended drawings in which:

[0008] [Fig-1] schematically represents a perspective and top view of a cylindrical part suspended from a lifting system according to the invention;

[0009] [Fig.2] is a schematic perspective view of the spreader bar used in the system lifting of [Fig.l];

[0010] [Fig.3] is a schematic perspective view of a detail of the slinging means for the lifting system of [Fig.l], illustrating the junction of a diagonal line with the head of a hanger;

[0011] [Fig.4] is a schematic perspective view of a detail of the slinging means for the lifting system of [Fig.l], illustrating the junction of the diagonal line of [Fig.3] with the foot of another hanger; and,

[0012] [Fig.5] is a schematic elevation view, illustrating two stages of adjusting the verticality of a lifted part.

[0013] In particular, the terms "top", "bottom", "upper" and "lower", "horizontal" and "vertical", "left" and "right" and other terms of the same type may be arbitrarily used in the present description and generally refer to the positions illustrated in the figures.

[0014] Figures 1 to 4 illustrate a lifting system 1 according to the invention. In the example illustrated, the system 1 is shown in the process of lifting a substantially cylindrical and symmetrical part 2 about a part axis X2. The system according to the invention is designed to ensure that, when lifting the part 2, the axis X2 forms with the vertical V an angle A2 less than a given value AD. That is to say, the part axis X2 is sufficiently close to the vertical to allow the part to be positioned in accordance with the expectations of a user.

[0015] The washing system 1 comprises a spreader bar 3 and slinging means 4. As particularly illustrated in [Fig.2], the spreader bar 3 comprises a head ring 11, a longitudinal beam 12 and two transverse balance beams 13. It further comprises straps 14 allowing the use of a double bridge hook. It also comprises spacers 15 connecting the balance beams together.

[0016] The head ring 11 comprises a yoke 1 IA formed around a lifting axis XI1 and provided for the passage along this axis of a bar, not shown. The bar is provided for fixing a hook of an overhead crane there. The straps are provided for alternately fixing the hooks of a double hook there. The yoke is articulated to the beam 12 around a horizontal longitudinal lifting axis XI1.

[0017] Each balance 13 extends horizontally, perpendicular to the beam; it is articulated at a respective end of the beam 12, around a longitudinal balance axis X13. In this example, the two balances are articulated around the same axis X13. Each of the spacers 15 connects a respective end of a balance with a respective end of the other balance.

[0018] The slinging means 4 comprise four hangers 20 and four lines 30. The hangers 20 are chains arranged vertically and which together take up the weight of the part 2. Each is attached by a high end 20H (see [Fig.3]) to a respective end 13T of a balance 13 and attached by a lower end 20B to a respective connector 26 of the part 2 (see [Fig.4]). In the following, the upper end of a hanger is called the head, and its lower end is called the foot; the foot and the head can be made up of several elements, in particular a hook and / or one or more links and / or one or more shackles which allow the positioning without twisting of the hanger.

[0019] The spacers 15 together constitute connecting means between the balances, allowing sufficient flexibility between the balances to guarantee an isostatic distribution of the loads between the hangers 30.

[0020] The hangers together constitute a parallelepiped. In the figures, each of the hangers 20 is identified by a number 21-24 which is specific to it. They constitute, two by two, two adjustment planes PI, P2 vertical and diagonal relative to the above-mentioned parallelepiped. Thus, a first hanger 21 defines, with a third hanger 23 which is diagonally opposite it, a first adjustment plane PL. A second hanger 22 defines, with a fourth hanger 24 which is diagonally opposite it, a second adjustment plane P2.

[0021] The slinging means 4 further comprise four adjustment lines 30. Each line 30 constitutes a diagonal of the above-mentioned parallelepiped. In the figures, each of the four lines 30 is identified by a number 31-34 which is specific to it. Among the lines 30: - a first line 31 connects the head 20H of the first hanger 21 to the foot 20B of the third hanger 23; - a second line 32 connects the head 20H of the second hanger 22 to the foot 20B of the fourth hanger 24; - a third line 33 connects the head 20H of the third hanger 23 to the foot 20B of the first hanger 21; and, - the fourth line 34 connects the head 20H of the fourth hanger 24 to the foot 20B of the second hanger 22.

[0022] Thus, the first line 31 and the third line 33 are substantially in the first adjustment plane PI, and the second line 32 and the fourth line 34 are substantially in the second adjustment plane P2.

[0023] Each line 30 comprises a tensioner 36 arranged between two strands 37 of the line (see [Fig. 3]). In the example illustrated, the strands are chains and the tensioners are chain spreaders. Each tensioner makes it possible to lengthen or shorten the corresponding line, that is to say, under load conditions, to tighten or loosen it more or less completely.

[0024] In the example illustrated in Figures 1 to 4, the various elements have the following dimensions.

[0025] - the head ring 11 is provided for fixing a rolling crane hook of the type: DIN 15402-B GBD250;

[0026] - the straps 14 are provided for fixing a double hook of the type:

[0027] DIN 15402-B GBD250; - the lifted part 2 has a height H2 equal to 4.8 meters, and a weight of 100 tons; - the first and third hangers 21, 23 and the second and fourth hangers are horizontally separated by a diagonal distance DD equal to 4034 millimeters; - the length H4 of the lines 20, between the attachment points of the lines 30 at the heads and feet, is five meters; - the height H3 of the spreader 3, between the hook axis XI1 and the attachment points of the lines 30 to the heads, is 3.3 meters;

[0028] [Fig. 5] illustrates a method for adjusting the verticality of the part 2, using the slinging system 4 according to the invention. [Fig. 5] is carried out in the first adjustment plane PL Only the third line 33 is illustrated. The same adjustment principle is applicable to the first line 31 in order to allow, by adjusting the two lines 31, 33 of the plane PI, the positioning of the part 2 in this plane PL

[0029] The same principle is applicable to the second adjustment plane P2 in order to allow, by an adjustment in each of the two planes PI, P2, the positioning of the part 2 in space.

[0030] The part 2 is substantially symmetrical relative to its axis X2, so that its theoretical center of gravity GT is located on this axis X2. However, in reality, as is the case in the illustrated example, the real center of gravity G is generally not confused with the theoretical center of gravity GT.

[0031] [Fig.5] illustrates two steps 5A and 5B of the adjustment method; a first, initial step, 5A and a second, final step, 5B.

[0032] Line 33 having an initial length L301, when the part 2 is lifted by the lifting system 1 and free from any other hindrance, the assembly [1,2] consisting of the lifting system 1 and the part 2 takes the position illustrated in step 5A. The real center of gravity G y is vertical to the lifting axis XI1 and the part axis X2 forms, with the vertical V, the instantaneous angle A2 already illustrated in [Fig.l]. At this first step, the instantaneous angle A2 is greater than a given maximum angle AM.

[0033] The hangers 21, 23 form with the spreader 3 and the part 2 a parallelogram ABCD. At the first step 5A, the parallelogram ABCD is not straight and the line 33 follows the largest diagonal BC. Modifying the length of the line 33 makes it possible to deform the parallelogram.

[0034] The purpose of the adjustment is, by modifying the length of line 33, to reduce angle A2 to a value less than the value of the maximum angle AM. Preferably, so that the value of the instantaneous angle A2 is as close as possible to zero.

[0035] In the second step 5B, which illustrates the final step of the adjustment, the length of the line 33 has been reduced to a length L302, so that the parallelogram ABCD has been distorted and the line 33 forms the smallest diagonal BC.

[0036] The hangers are no longer strictly vertical and the line takes up part of the mass of part 2. In the example illustrated, the load taken up by a line is close to one tonne, or approximately 1% of the mass of part 2.

[0037] In this position, the axis X2 is substantially vertical, that is to say that the instantaneous angle A2 has a residual value close to zero, less than the value of the given maximum angle AM.

[0038] The other line 31 can be kept relaxed.

[0039] The residual value of the angle A2 depends on the precision of the adjustment means 36 (not shown in [Fig.5]). Thus, in the case of the hoists 36, this precision is inversely proportional to the pitch of the hoist - generally this pitch is equal to the length of a link, for a chain hoist - and proportional to the number of pulleys.

[0040] A system according to the invention allows a coarse primary adjustment of the position of the load under the lifting beam. The same system also allows a fine secondary adjustment. The adjustments can be made under load, that is to say with the part already lifted, while requiring only low adjustment forces. The use of hoists allows both low forces and very high sensitivity, that is to say high precision of adjustment. In addition, the diagonal lines constitute a bracing which ensures good stability of the load during its lifting, its movement and its positioning.

[0041] Of course, the invention is not limited to the examples which have just been described. On the contrary, the invention is defined by the claims which follow.

[0042] It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0043] Thus, it is possible to provide motorization and remote control of the tensioners.

[0044] Also, it is possible to lift a load with only two hangers defining a single adjustment plane, under conditions similar to those illustrated in [Fig.5]. This is particularly useful if the load is substantially flat, such as a concrete wall, or if the precision of the inclination in a direction perpendicular to the single adjustment plane is not crucial.

[0045] It is also possible to provide a spreader bar offset, greater than the expected load offset, for example with balance beams which are not arranged symmetrically. relative to the lifting axis. Thus, a single diagonal line per adjustment plane is sufficient to correct the load offset.

[0046] An adjustment method according to the invention is applicable to any type of part, whether or not it has symmetry.

Claims

Demands

1. System (1) for lifting a part (2), characterized in that it comprises a spreader bar (3) and slinging means (4); said slinging means comprising four suspension lines, for suspending said part from said spreader bar; said spreader bar comprising a longitudinal beam (12) and two swing arms (13) transverse to said beam, each articulated to a longitudinal end of said beam, each suspension line being suspended from a respective end (13T) of a respective swing arm (13), said suspension lines together forming substantially a parallelepiped and defining in pairs (21, 23; 22, 24) two adjustment planes (PI, P2) diagonal to the parallelepiped; said slinging means further comprising, in each of said adjustment planes, at least one adjustment line (31, 33; 32, 34) diagonal to said suspension lines in said adjustment plane, and tensioning means (36) for said line.

2. System according to claim 1, characterized in that in each adjustment plane (PI; P2) the two slings (21, 23; 22, 24) which define this plane, also define a parallelogram (ABCD) of which at least one line forms a diagonal (BC).

3. System according to any one of claims 1 and 2, characterized in that the tensioning means are a hoist (36).

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