EP1979259B1 - Hook of a crane - Google Patents

Abstract

The invention relates to a lifting gear having a receptacle for receiving the component of a load, on which component the load is raised, and in particular to a hook (1) of a crane having at least one piezoelectric element (20) which is arranged in the region of the hook mouth (3) in such a way that it is loaded by the weight of a load which is carried by the hook (1), which weight is transmitted to the hook (1) via a journal (4) which is held in the hook mouth (3).

Description

The invention relates to a hook of a crane and in this particular possibility of monitoring the correct load picking by the hook and takes the priority of the German patent application 10 2006 001 423.5 to complete.

Already from the 1957 published AT 192 857 is the effort known to monitor the load bearing a hook with a pressure cell, since the crane operator can hardly reasonably perform such monitoring due to its position to the hook significantly spaced position. AT 192 857 suggests to put a pressure cell as a trigger contact at the bottom of the hook mouth. As soon as the hook loads the pressure cell, it sends a signal. Due to the arrangement of the pressure cell in the bottom of the hook mouth, the delivery of the signal is synonymous with the correct detection of the load, as the picked up by the hook jaw pin the load comes into contact only with the pressure cell when it is in the hook mouth. A disadvantage of the crane transport of molten masses in pans is the arrangement of the trip contact - pressure cell - in the power main circuit, which makes a to the usually large load adapted load capacity and thus size of the contactor required. Furthermore, a patch on the jaw pressure cell reduces the depth of the hook mouth and thus the security of the complete recording of the pin in the jaw, or the security against falling out of the pin with an angle held hook.

DE 44 47 393 C1 teaches a training of AT 192 857 Known principle and proposes to provide two inductive sensors in the jaw of a lamellar hook of a huts crane. These sensors can determine the positive connection of the hook mouth with the pin contact. This can make the DE 44 47 393 C1 Also recognize known construction when the pin approaches the hook mouth. This will be a disadvantage of AT-PS 192 857 known device that can not indicate the approach to the load, so that the crane operator under Circumstances must make several blind raises before he has picked up the load correctly.

The sensors respond to the approach of conductive, metallic objects. The sensors are installed in recesses of the jaw, which open to the jaw. These recesses are closed by a cover that does not affect the induction principle to the journal support side of the jaw.

When threading the Pfannengehängezapfens in the jaw takes place a switching of the output signal, if the defined switching distance of the sensors is exceeded, or a downshift, if the switching distance should be exceeded. Due to the geometric relationships between the socket and jaw and the defined size of the switching distance, the proper position of the pin is clearly detected in the jaw. This sensor arrangement takes into account both the safety requirements (two redundant sensors per hook) and the environmental conditions (encapsulation in the mouth shells).

A disadvantage of the DE 44 47 393 C1 known construction is that the inductive sensors must be provided in recesses of the inner surface of the jaw shell in order to determine the approach of the pin to the bottom of the jaw shell. In this case, the recess must not be closed with the inductive effect of the sensors influencing covers. In particular, under the operating conditions of a steelworks, the high abrasive loads, especially characterized by dirt and scale, this design is adversely affected or requires special, the elasticity limiting armor, since it can cause damage to the covers. Furthermore, it has been found in practical operation that this known construction nevertheless leads to incorrect measurements, for example, if metal splashes from the melt settle on the cover of the sensors. The inductive measuring sensors can not distinguish between these splashes of the melt and the pin of the load, so that a positive measurement indication takes place, although the pin was not recorded in the hook mouth.

Against this background, the present invention seeks to propose a structure for a hoist with a receptacle for receiving the component of a load on which the load is raised, and in particular a structure for the hook of a crane, with which the recording of the male component can be reliably determined in the intended recording.

This object is solved by the subject matter of claim 1. Advantageous embodiments are specified in the subclaims.

The invention is based on the basic idea to determine the correct absorption of the load by receiving a hoist by checking whether a weight is transmitted to the hoist in the area of the receptacle. Only then can it be determined with certainty that the element to be lifted, for example the pin to be picked up by the hook mouth, is actually located in the receptacle.

To determine this weight transfer, the invention proposes to arrange a piezoelectric element in the region of the hook mouth of a hook of a crane, that it is only loaded by the weight of the load carried by the hook when the hook mouth holds the pin properly. The use of a piezoelectric element offers the advantage of a compact size, which allows installation in standard hooks, such as the standard single-hook according to DIN 15407 for pig iron and steel ladles, without having to deviate from the standard dimensions. Nevertheless, the piezoelectric element allows a reliable detection of the loads loading it.

During proper threading of the pin in the hook mouth immediately after the initiation of the lifting operation and the associated initiation of the lifting force from the pin into the jaw occurs elastic deformation of the jaw. This deformation is detected by the sensor and detected by an evaluation. In case of improper threading of the pin in the jaw, z. B. when lifting the load with the hook tips, so outside the jaw, this sensor signal is not generated due to the intended installation. When the load is released, the jaws are relieved, which is also detected by the sensors and detected by the evaluation electronics.

By the piezoelectric element according to the invention is arranged in the region of the hook mouth and not for example at the top of the hook or in areas between the hook jaw and the suspension, it is ensured that the piezoelectric element indicates a load only when the pin transmitting the load is actually in the Hook mouth is located.

As a piezoelectric element is particularly suitable as a so-called Cluarz-measuring dowel. These sensors are suitable to measure the forces in structures of machines, tools, etc. indirectly via the strain.

In a preferred embodiment, the piezoelectric element is arranged in the region of the hook mouth. Here it can determine whether the hook mouth is loaded by a weight force. If this is the case, the pin is also in the hook mouth, so that the correct load bearing is detected correctly. Furthermore, the use of a single piezo element offers a cost advantage.

According to an alternative embodiment, two piezo elements are arranged opposite each other outside of the hook mouth. For safety reasons, it may be desired, for example, to provide two piezo elements in the hook should one of the piezo elements fail. In order not to weaken the hook mouth in the region of its base too much by recesses for receiving piezoelectric elements, the piezoelectric elements outside the hook base, for example, on the edge side as in DE 44 47 393 C1 arranged inductive sensors arranged. Also in these positions, the piezo elements are loaded at least by a component of the weight transferred from the pin to the hook, so that they can reliably display the reception of the pin in the hook mouth even in this position. This is even more true when heavy loads are transported through the hook. This leads to a significant load on the piezo elements, which can be determined very reliably.

In a preferred embodiment, at least one piezo element is arranged in a recess of a jaw shell of the hook jaw. Hooks, in particular the lamellar hooks used by lodge cranes often have a mouth protecting the hook's mouth. This jaw shell regularly has a wall thickness of more than 35 mm, so that it can accommodate, for example, conventional cylindrical piezoelectric elements with a diameter of 10 mm, without a change in the outer shape of the mouth shell must be made. This also offers the advantage of being able to easily retrofit existing hooks, since in the simplest design, only the mouth socket needs to be exchanged or machined, that is, for example, a recess has to be introduced into the jaw shell.

By providing a force sensor in a recess of the hoist itself and a guide of the recess so that it has no opening for receiving, an encapsulation of the force sensor is achieved in the hoist itself, which weakens the hoist itself is indeed weakened to a small extent, the However, the measuring device given a good temperature resistance in the absence of a direct contact with the component of the load on which the load is raised becomes. Depending on the routing of the recess, the surrounding wall of the hoist even exerts an insulating effect. Furthermore, the proposed measuring arrangement is insensitive to metallurgical dust, since contact with the metallurgical dust can be well avoided. This is often stored in recordings, such as those of the hoist from. However, the outlet of the recess is not formed in the receptacle, but may for example take place at a point of the hoist, where no deposition of cottage dust is possible, such as on an underside of the hoist. Also, the proposed measuring arrangement is resistant to mechanical stress, since the force sensor is protected in the recess.

In a preferred embodiment, the recess receiving the piezoelectric element is oriented perpendicular to the radial direction of the jaw shell defined by the curvature of the jaw shell. This makes it possible to make the recess sideways, whereby the insertion and replacement of the piezoelectric element is simplified. In addition, the pin facing inner surface of the jaw remains untouched, so that with the off DE 44 47 393 C1 Known covers of recesses on the inner surface of the jaw known problems can be avoided. In a further preferred embodiment, the recess is introduced from the underside into the mouth shell. Thus, there are no openings, holes or the like in the area of the support surface of the jaw claws and, consequently, a deterioration of the sensors is excluded by the environmental conditions.

In a preferred embodiment of the invention, measures are provided to lead cables that are necessary for connecting the piezoelectric element with an evaluation, protected. In a preferred embodiment, a cable is to be prevented from being guided along an outer surface of a component of the hook, since such a cable can catch and tear against surrounding elements or be crushed and damaged in contact with other elements. In a preferred embodiment, the mouth of the hook has an inner surface, which comes into contact with the pin of the load, and an adjacent to the inner surface, standing at an angle to the inner surface side surface in which a groove is provided, which receives from the piezoelectric element Recess runs along the side surface. In this groove, a cable can be inserted, so that this cable is prevented, for example, rests against the outer surface of the side surface and is damaged there. In particular, this groove is preferably closed by an attached cover, so that the groove and in particular the recess receiving the piezoelectric element are protected.

In a preferred embodiment, the groove terminates at a cable recess in the jaw shell which extends from the side surface into the interior of the jaw shell. Depending on the construction of the hook, it has proven to be advantageous to lead out the cable to be continued by the mouth shell in the region of the center (as seen in the width direction of the hook) of the jaw shell from the mouth socket and from there continue, for example, through a through hole in the hook. This central guide of the cable ensures a particularly good protection of the cable.

Particularly preferably, the hook is designed as a lamellar hook of a huts crane, since the advantages achieved by the invention in huts cranes are particularly large.

In a preferred embodiment, a cable connected to the piezoelement is guided into a channel of a blind lamella. This has the advantage of protecting the cable from the house dust, the direct radiant heat and from mechanical damage.

In a preferred embodiment, an evaluation unit is connected to the piezoelectric element, which can determine the weight of the load received by the hook from the signal emitted by the piezoelectric element.

Alternatively, an evaluation unit can be provided which converts the signal output by the piezoelectric element into a binary signal, wherein one value indicates the loading of the piezoelectric element with a weight force above a certain threshold value and the other value indicates the missing load.

The signal emitted by the piezoelectric element can be amplified by a charge amplifier provided in the region of the hook or on the hook. This is particularly preferred if one (the) evaluation unit itself is arranged at a considerable distance from the hook. For example, the evaluation unit may be arranged in the crane cab. Particularly preferably, the charge amplifier is temperature-protected by a special housing or optionally even cooled. This facilitates the use of a charge amplifier in the area of lifting molten metal melts and the heat radiated from them.

Fig. 1

eine perspektivische Ansicht einer Blindlamelle eines erfindungsgemäßen Lamellenhakens mit einer in das Hakenmaul eingesetzten Maulschale,

Fig. 2 eine

vergrößerte Teilansicht eines Details der Blindlamelle und der Maulschale nach Fig. 1 und

Fig. 3

ein weiteres Detail der Maulschale des erfindungsgemäßen Lamellenhakens.

The invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. It shows:

Fig. 1

a perspective view of a blind blade of a laminated hook according to the invention with a jaw shell inserted into the hook mouth,

Fig. 2 a

enlarged partial view of a detail of the blind blade and the mouth socket behind Fig. 1 and

Fig. 3

a further detail of the mouth of the lamella hook according to the invention.

Fig. 1 shows the lower portion of a blind slat 1 a composed of several juxtaposed slats lamellar hook, as standardized, for example, in DIN 15407. In the hook mouth of the slats a mouth 3 is arranged. The jaw cup 3 receives the pin 4 of a load received by the hook, for example, a pig iron and steel ladle.

The blind blade has a leading through the blind blade 1 and along the blind blade continuing recess 5, in which a cable 6 is performed. In the angle to the load-receiving inner surface of the jaw 3 standing side surface 7 of the mouth 3, a groove 8 is provided. How out Fig. 2 Particularly clearly visible, this recess extends along the side surface 7 of the mouth shell 3. In this case, it connects a recess 9 with a Kabelausnehmung, 10, which extends from the side surface into the interior of the mouth 3. This cable recess makes it possible, as shown in the perspective view of Fig. 2 clearly visible, the cable 6 in the middle of the mouth 3 out of the jaw 3 out and into the recess 5. In the recess 9, a piezoelectric element 20 is provided.

The Fig. 3 shows the arrangement of the piezoelectric element 20 in the recess. 9. In addition, it can be seen in this figure that the dummy lamella 1 is arranged between further lamellae 11. In addition shows Fig. 3 in that the recess 9 and the groove 8 can be closed by a cover 12.

To pick up a load, the hook is brought by the crane operator to the pin so that it is picked up by the hook mouth. In this case, the pin comes to lie on the jaw shell with proper recording of the load. A slight lifting of the hook causes the weight of the pin 2 to press the jaw. This pressure is at least partially forwarded by the jaw shell to the piezoelectric element 20, which is thereby loaded and emits an electrical signal. The delivery of the electrical signal allows the crane operator to recognize that the load has been properly recorded in the hook mouth and not rests for example on the top of the hook.

The Fig. 1 shows further that in the jaw 3, two recesses 9 are provided, in which redundant piezo elements are arranged in order to obtain a reliable signal on the correct recording of the load even in case of failure of a piezoelectric element.

Claims (9)

1. Hook of a crane having at least one sensor which is arranged in the region of the hook opening, characterised in that the sensor is a piezoelectric element (20) which is arranged in the region of the hook opening so that it is then only loaded by the weight of a load carried by the hook if a trunnion (4) of the load is held in the hook opening.
2. Hook according to Claim 1, characterised in that the piezoelectric element (20) is arranged in the region of the base of the hook opening.
3. Hook according to Claim 1, characterised by two piezoelectric elements (20) which are arranged opposite one another outside the immediate base of the hook opening.
4. Hook according to any one of Claims 1 to 3, characterised in that at least one piezoelectric element (20) is arranged in a recess (9) of a cup (3) of the hook opening.
5. Hook according to Claim 4, characterised in that the recess (9) runs perpendicular to the radial direction of the cup (3) of the opening defined by the curvature of the cup of the opening.
6. Hook according to Claim 4 or 5, characterised by an inner surface of the cup (3) of the opening, which comes into contact with the trunnion (4) of the load, and a side surface (7), adjacent to the inner surface and situated at an angle to the inner surface, in which a groove (8) is provided, which starting from the recess (9) which accommodates the piezoelectric element (20), runs along the side surface (7).
7. Hook according to Claim 6, characterised in that the groove (8) ends at a cable recess (10) in the cup (3) of the opening, which extends from the side surface (7) into the interior of the cup (3) of the opening.
8. Hook according to any one of Claims 1 to 7, characterised in that the hook is designed as a laminated hook of a foundry crane.
9. Hook according to Claim 8, characterised in that a cable (6) connected to the piezoelectric element (20) is guided in a channel of a dummy lamella plate (1).

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