Description

Technical field of the invention

The present invention refers to a fastening device comprising of a loop portion adapted for attaching a lifting, fastening and/or lashing means and an anchoring portion for anchoring in an object, wherein the loop portion and the anchoring portion form a unit, the loop portion having a more than two-fold, in mainly, rotationally symmetrical shape, preferably threefold.

Background and prior art

Lifting eye screws/nuts according to DIN580 and DIN582 are known and constitute simple and cost-effective solutions for lifting objects. DIN580/582 specifies the permissible weight of what is to be lifted for different sizes of lifting eye screws/nuts. Hereinafter, lifting eye screws/nuts according to DIN580/582, or similar, will be referred to as lifting eyes. DIN580/582 also allows lifting with two lifting eyes provided that the lifting eyes are placed so that they are in a common plane. DIN580/582 also states that lifting eyes must be screwed firmly against the surface of the object to be lifted. However, this makes it difficult to ensure that the lifting eyes after installation are in the common plane. The reason for the difficulty lies in getting the threads for the lifting eyes and the threads for the lifting object adapted to each other with increased cost to ensure this. It should also be pointed out that lifting can take place with more than two lifting points, whereupon lifting eyes according to DIN580/582 cannot be used if the standard is to be met.

The problem with lifting eyes according to DIN580/582 lies in the unfavorable load cases that arise in the case that the force acts out from the plane of the lifting eye, which corresponds to the load case simply supported beam with a non-strength- favorable cross section. According to DIN 580/582, the load case is not permitted, but the forces that could be absorbed in such a load case are significantly lower than forces in the plane of the lifting eye. This applies to the case when lifting, but also to the case where one or more lifting eyes act as fastening or lashing elements with subsequent load cases outside what DIN580/582 specifies. According to DIN580/582, lifting eyes must be screwed firmly against the object, but the standard does not specify which torque is to be applied. If the lifting eye is not screwed on properly so that enough friction is achieved between the lifting eye and the object, the force can give rise to torque which may unscrew the lifting eye. It should be pointed out that the torque can only rotate the lifting eye at most half a turn, i.e. until the force has turned the lifting eye so that the torque lever has been released. If the lifting eye's anchoring portion has a gap against the object, the force will act on the cross section of the lifting eye's screw part, instead of the base of the lifting eye's anchoring portion, which gives increased stress and increased risk of failure. The above-mentioned problems give rise to the need for lifting points with a rotating function and as described in, for example, EP 0 654 611 B1. Unlike previously described lifting eyes, these rotating lifting points consist of at least two separate parts, loop and anchoring part, usually several, which enables rotation of the loop so that the lifting force comes in a load-favorable direction. Increased complexity of rotating lifting point increases the cost compared to lifting eyes. EP 1 456 560 B1 also addresses the problem that high friction in the rotational function of rotating lifting point can counteract rotation, which can be solved with ball bearing-like solutions between the loop and the anchoring part. Although it is a better solution to achieve the ability to rotate, it leads to even more parts for rotating lifting points and even higher costs compared to lifting eyes.

Summary of the invention

The object of the invention is to ensure a shape of a fastening device which can more effectively absorb forces in arbitrary directions and at a cost which more closely corresponds to standardized lifting eyes according to DIN580/582 and which is not based on several separate components. The object of the invention is also to reduce the risk of handling errors.

Objectives are solved by using a more than two-fold, in mainly, rotationally symmetrical shape, preferably threefold, so that a design for a fastening device is created that has higher strength. The three-fold rotationally symmetrical case is most easily visualized by imagining a DIN580/582 lifting loop divided into two half circles. Three half circles, corresponding to three half lifting eyes, are joined at the bottom and at the top and roughly form the shape of the invention with the case three-fold, in mainly, rotational symmetry. Structural analysis for this type of design give significantly better values than for lifting eyes according to DIN580/582, as the three-fold symmetry planes cooperate when absorbing forces in arbitrary directions. Although more planes of symmetry can be used, the advantage of three planes of symmetry is that the attachment of lifting, fastening and/or lashing means to the fastening device is not limited to the same extent as in the case of more half circles. This is because several half circles result in the distance between the respective half circles decreasing, and thus complicates the attachment of lifting, fastening and/or lashing means. The invention is based on creating a better design with higher strength instead of allowing rotation in a strength-favorable direction. The invention also reduces the risk of handling errors because the, in mainly, rotationally symmetrical shape reduces the risk of incorrect assembly and incorrect use by forces not having to relate to a certain direction. The invention eliminates the disadvantages of DIN 580/582 without introducing the disadvantages of rotating lifting points.

The invention is intended to be attached to the object for the purpose of achieving friction in order to avoid rotation. In the case that the fastening portion of the invention is shaped like a nut, commonly used torque wrenches can be used to apply the recommended torque during assembly to avoid rotation.

The invention is intended to be used for lifting, lowering, moving and/or securing cargo in the form of goods or persons. Areas of use that may be referred to include, but are not limited to, the construction industry, the manufacturing industry, the transport industry, marine and ports, the defense industry, the steel industry, the paper industry, the mining industry, the energy industry, the entertainment industry, ski resorts, the food industry, agriculture etc.

The invention can be carried out in various materials, for example, but not limited to, metallic materials, composite materials, polymeric materials, etc., and with various surface treatments, for example, but not limited to, painted, oxidized, etc., or untreated.

The invention can be manufactured by various methods, for example, but not limited to, casting with lost wax process, sand casting, shell-mold casting, additive manufacturing, etc., and with any subsequent processing. The invention can also be manufactured in different parts and then joined to a unit, e.g., but not limited to, welding, gluing, etc.

Further features and details of the invention appear from the claims and the following description of an embodiment of the invention produced in the accompanying drawings.

Description of drawing

Fig. 1. Example of a screw embodiment of the invention with the case three-fold, in mainly, rotational symmetry.

Definition of certain terms

Rotational symmetry. If a shape is rotated around a point, after it has been rotated an entire revolution, it will look the same as it did from the beginning. If at some point during the rotation, before an entire revolution has been rotated, it corresponds to its original shape, then the shape exhibits a rotational symmetry. The number of times the shape repeats during one revolution indicates the order of rotation. In the two-dimensional case, a rectangle has a symmetry that repeats twice, the equilateral triangle has a symmetry that repeats three times, a square that repeats four times, and so on. It is said that the rectangle has a two-fold symmetry, an equilateral triangle has a three-fold symmetry, the square a fourfold one, and so on.

Lifting eyes according to DIN580/582 have a three-dimensional shape that repeats twice, i.e. a two-fold rotational symmetry when rotating along a vertical axis. Description of an embodiment example

Figure 1 refers to the case of a, in mainly, three-fold rotational symmetry. Reference numeral (1 ) denotes a loop arche of a fastening device. The other two loop arches have reference numerals (2, 3) and together they form the loop portion (4) of the invention. Reference numeral (5) refers to the anchoring portion. The anchoring portion can either be provided with a threaded pin (6), which constitutes the screw case, or with a threaded hole in the anchoring portion (5), which constitutes the nut case for the fastening device.