EP1354840B1 - Gripper - Google Patents

Abstract

The gripper for the transporting of containers comprises a crossbeam (1) fastened to a lifting device, and diametrically opposite support arms (3) protruding downwards from the crossbeam and with gripping elements (4) on their lower ends to grip under the surfaces (5) of the containers (6). The distance between the support arms matches the diameter of the containers. Two centering arms (8) offset by 90 degrees from the support arms protrude downwards from the crossbeam, and the distance between them conforms to the diameter of the containers.

Description

The invention relates to a gripper according to the preamble of claim 1 for transporting containers, which are arranged in a vertical orientation.

The containers discussed here are, above all, shielding containers for receiving radioactive material. Individual groups of containers have mutually different, but within the groups uniform dimensions.

From the GB-A-2037251 is a gripper of the generic type is known in which the two support arms are arranged radially adjustable on the gripper cross member and can be delivered by radial adjustment of the container to be gripped. The gripping elements must be shaped so that they set the container to be gripped in all directions and center around the gripper axis. Since the support arms must be delivered radially, this known gripper formation requires relatively large minimum distances between the containers to be taken.

The invention is based on the object to provide a gripper of the type mentioned, which is able to take the container even then and to hold reliably when they are close together.

Starting from a gripper of the type mentioned, the solution of this problem by the characterizing features of claim 1 succeeds.

This gripper can be referred to as a two-armed gripper, since it has only two support arms. The two centering arms ensure that the gripper is lowered centrally to the respective container.

The gripper is able to pick up the containers even if they are close together. Often the containers are delivered as a "six-pack". The six containers in the plan form a rectangle, which is surrounded by tight-fitting walls. Nevertheless, the gripper is able to grab and lift each individual container from the "six-pack". Of course, the containers are often delivered in a different formation, but usually close together, so tightly packed. The same applies to the storage of the containers. The main advantage of the invention is to accommodate such densely packed containers, transport and be able to settle again in dense formation. Of course, freestanding containers can also be handled.

The gripper according to the invention is applicable to containers of different cross-sectional shapes, including polygonal containers, for example square, octagonal or sixteen-cornered containers, or oval containers. However, the main field of application of the invention are round containers, as represented by the shielding containers already mentioned above.

The four arms of the gripper, which are preferably exactly at right angles to each other, find enough space between the male container and the adjacent containers or walls. A three-armed gripper, as is known in practice, is not able to do this.

The two diametrically opposed support arms have sufficient carrying capacity to transport all candidate containers. An axial load on the centering does not occur. The main function of the centering arms is to let the support arms engage in a position on the containers in which the container weight is evenly distributed on the support arms. With pendulum movements of the load, the centering arms take over also radial support functions. Slipping out of the container from the support arms is reliably prevented.

The length of the support and centering can be chosen so that containers of different heights can be transported. An adaptation of the gripper is then actually required only in the radial direction, depending on different container diameters.

You can design different grippers for different container diameters. Under certain circumstances, it is more advantageous to arrange the carrier and / or the centering arms radially adjustable on the gripper crossbar. The gripper is then able to handle containers of different diameters.

The engagement surfaces that are engaged by the gripping elements of the support arms can be designed differently. For example, it is possible to provide separate recesses in the container outer walls whose upper boundaries form the engagement surfaces and in which the gripping elements can engage. The position of the recesses above the container height can be chosen arbitrarily. The formation of recesses requires that the gripper is lowered in a defined angular position on the container. Accordingly, it may be more advantageous to form the engagement surfaces of the containers as circumferential shoulders. The angular position of the gripper does not matter under these circumstances. The circumferential shoulder can be formed by the upper boundary surface of a groove, which is arranged at any height in the container wall. As a rule, one will proceed so that the circumferential shoulder is formed by a recess at the bottom of the container.

Preferably, the gripping elements are formed as pawls, which are each rotatable about a vertical axis passing through the associated support arm. For this purpose, it is proposed in development of the invention that the pawls each mounted in the associated support arm and extending from one in the support arm vertical shaft are driven. The essential advantage of this construction is that the waves which cause the movement of the pawls are kept free of the forces generated by the container load. You only need to be able to pivot the pawls in the unloaded state. The forces generated by the load are introduced by the pawls directly into the associated support arms. In principle, it is possible to equip each support arm with two pawls rotating in opposite directions to one another and to drive them via separate shafts or else via a common shaft. It is structurally easier to provide each support arm with a single pawl.

Since the support arms are exposed to certain elastic deformations, it is advantageous to connect the shafts in each case via a universal joint to an associated drive.

In principle, it is possible to use a common drive. On the other hand, it is more advantageous to assign a separate drive to each shaft, wherein the drives are preferably designed as worm geared motors. If the support arms are radially adjustable, you will choose the construction so that the drives are adjusted together with the support arms.

Disturbances of the systems can not be excluded by their nature. Thus, it is conceivable that one of the pawls can not be opened on the associated drive after discontinuing a container. For this case, it is proposed that the drives are manually operated.

The end positions of the pawls are preferably defined in each case by stops. The attacks will form adjustable and preferably arrange in the gripper traverse, ie directly below the drives, which preferably sit on top of the crossbar.

An essential development of the invention is that the end positions of the pawls are each monitored by limit switches in pairs on one of the associated shaft driven cam run. With the cam, it is possible in a particularly simple manner to detect the changes in position of the pawls. After all, these are changes in angular positions. One of the limit switches signals the open position and the closed position of the associated pawl.

An essential safety aspect of the entire system is taken into account by the fact that at least one of the centering arms carries at its lower end a sensor which is directed radially inwardly and detects an engagement surface of the container. If the gripper drops to one of the containers, the sensor locks the pawls in their sideways or outward release position until it is below the height of the engagement surface. The arrangement is such that in this position, the pawls are at a level below the associated engagement surface. The sensor now signals a release for the jack drives. These turn the pawls in their closed position, defined by the associated stops and monitored by the associated limit switches. Once the latter signal the locking process as finished, the gripper can be raised, the pawls engage the engaging surfaces of the container and take the latter. The sensor of the centering automatically runs in a region of the container wall, which lies above the engagement surface. The sensor thus disables the jack drives, so that an opening of the pawls is excluded under load. Only when the container has been lowered again and the sensor has moved into the area below the engagement surface, the jack drives can come back into action. Should one of the drives fail, the container will be transported to a repair station where the defective drive will be manually operated and then repaired.

When the engagement surfaces for the latches of the support arms are formed by separate recesses or pockets, the engagement surface for the sensor of the centering arm is also formed as an upper surface of a pocket. This may be readily provided level differences between the sensor and the pawls. The construction becomes particularly simple if all engagement surfaces are formed by a common shoulder. The sensor is then at the same level as the latches. If the shoulder forms the upper surface of a groove or pocket, its height must be sufficient to permit actuation of the pawls if the sensor has fallen sufficiently below the level of the shoulder to be activated.

Basically, the arrangement of a sensor on one of the two support arms is sufficient. For safety reasons, it is preferable to equip each of the support arms with a separate sensor. Only the release signals of both sensors then allows actuation of the pawl drives. The sensors are preferably designed as ultrasound proximity switches.

About the sensor or the sensors is an electronic locking of the pawls of the support arms under load. Preferably, in addition to a mechanical locking is provided, through appropriate dimensioning of the drive power and the gear ratio. The frictional resistance of the pawls under load is so great that the drive power is not sufficient for an operation.

As mentioned, the gripper is above all suitable for attachment to a crane. He can be struck at the load hook of the crane or be connected via rollers directly to the trolley of the crane. The suspension is usually not rotatable, but allows pendulum movements of the load. Is the gripper raised up to the highest height position relative to the trolley of the crane and is moves the trolley or the crane, such pendulum movements of the load are undesirable. Accordingly, it is proposed in development of the invention that the cross member carries at least one upwardly projecting pin for engagement in a complementary recording of the lifting device. In the case of a crane, the complementary receptacle is in the trolley. Basically, an upwardly projecting pin is sufficient. On the other hand, two diametrically opposite pins are more advantageous.

• Figur 1 eine Seitenansicht eines Greifers nach der Erfindung;
• Figur 2 eine Vorderansicht des Greifers nach Figur 1;
• Figur 3 einen Grundriß des Greifers nach Figur 1 und Figur 2;
• Figur 4 eine Einzelheit aus Figur 1;
• Figur 5 eine Einzelheit aus Figur 2.

The invention will be explained in more detail below with reference to a preferred embodiment in conjunction with the accompanying drawings. The drawing shows in:

• FIG. 1 a side view of a gripper according to the invention;
• FIG. 2 a front view of the gripper after FIG. 1 ;
• FIG. 3 a plan of the gripper after FIG. 1 and FIG. 2 ;
• FIG. 4 a detail FIG. 1 ;
• FIG. 5 a detail FIG. 2 ,

The gripper after the FIGS. 1 to 3 has a gripper beam 1, which is posted on a load hook 2 of a crane. From the gripper beam 1 protrude two load arms 3 down, which are arranged diametrically opposite each other. Each support arm 3 has at its lower end a gripping element in the form of a pawl 4. In the position after FIG. 1 The pawls 4 engage behind a circumferential shoulder 5 of a container 6 formed by a recess, in the present case a shielding container. The distance between the two support arms 3 is adapted to the diameter of the container 6. Centering elements 7 ensure a central alignment.

From the gripper beam 1 also protrude two centering 8 down. These are also arranged diametrically opposite each other and offset by 90 ° against the support arms 3. The Centering arms 8 are provided with centering elements 9, which correspond to the centering elements 7 of the support arms 3.

When the container 6 is to be picked up, the gripper is moved centrally over the container and then lowered. The pawls 4 take their opening position accordingly FIG. 3 one. Once the gripper is lowered so far that the pawls 4 can engage under the circumferential shoulder 5 of the container, the pawls 4 from its open position according to FIG. 3 in their closed position according to FIG. 1 pivoted. This is effected in each case by a vertical shaft 10, which passes through the associated support arm 3 and is connected with the interposition of a universal joint 11 to a Schneckenstirnradgetriebemotor 12. The Schneckenstirnradgetriebemotoren 12 are arranged on the gripper beam 1. The pawl 4 are mounted in the associated support arms 3, so that no forces are exerted on the vertical waves 10 by the load of the container 6.

The respective end positions of the pawls 4 are defined by stops, not shown. The latter are adjustably seated in the area of the helical-bevel geared motors 12. Furthermore, the end positions of the pawls 4 are monitored. According to FIG. 4 For this purpose, each latch two limit switch 13 (only one is visible in FIG. 4 ), which run on a cam 14. The latter is driven by the associated vertical shaft 10. A raising and lowering of the gripper is only possible when the pawls 4 occupy one of their end positions.

FIG. 5 shows that each sensor 8 is associated with a sensor in the form of an ultrasonic proximity switch 15. The proximity switches 15 are as clear FIG. 2 seen, directed against the container 6.

When lowering the gripper, the proximity switch 15 lock an operation of the Schneckenstirnradgetriebemotoren 12. Only when the circumferential shoulder 5 forming Return is reached at the bottom of the container 6, this block is released. This ensures that the pawls 4 have reached a position in which they can engage under the circumferential shoulder 5.

Have the pawls 4 taken their closed position and the gripper in the in FIG. 1 shown position has been raised, the proximity switch 15 are again the wall of the container 6 opposite. This means that the Schneckenstirnradgetriebemotoren 12 are locked again, so that an opening of the pawls 4 under load is impossible.

In addition to this electronic lock, the gripper has a mechanical lock. For this purpose, the drive power and the gear ratio are dimensioned so that an opening of the pawls under load is not possible.

Like from the FIGS. 1 to 3 can be seen, the gripper beam 1 is provided with two upwardly directed pin 16. These are arranged diametrically to each other and serve to engage in corresponding receptacles of the trolley of the crane. This prevents the load from swinging in the raised position. The insertion of the pin 16 in the recordings is done automatically, since the load hook against its suspension is rotatably.

The control of the gripper may be coupled to the control of the crane. Monitoring is possible by visual contact or via cameras and associated monitors. In the case of a fault, the gripper is optionally moved together with container 6 in a repair station in which the grippers are possibly opened by manual operation of the Schneckenstirnradgetriebemotoren. If it is a high-dose shielding container, the manual operation is performed using remote-controlled manipulators. At this point be hervehehoben that the gripper of the invention due to its design especially suitable for handling also shielding containers with high dose performance. The proportion of electronic components is low, and these can easily be provided with simple shields as needed.

The gripper is simple in construction and reliable in operation. It allows the inclusion of containers that are arranged in a vertical orientation close to each other.

In the context of the invention are quite possible Abwandlungsmöglichkeiten. Above all, the circumferential shoulder, which forms the engagement surface for the pawls, may also be the upper surface of a groove. However, then the axial extent of the groove should be sufficient to let the ultrasonic proximity switches take effect. Usually one will train the shoulder, however, as they in the FIGS. 1 and 2 is shown. The engagement surfaces can also be formed by pockets. Another Abwandlungsmöglichkeit is to form only one of the centering, namely the one which is provided with an ultrasonic proximity switch in full length and shorten the other Zentrierarm so that it only fulfills its Zentrierfunktion. However, the same length Tragund Zentrierarme have the advantage that the gripper can be parked without tools on the ground. The pins that prevent the pendulum movement of the gripper when the load is raised, can be arranged so that they fulfill their function both during travel movements of the trolley and during movements of the crane bridge. The length of the pins depends on how far the topmost height position of the gripper is removed from the trolley of the crane. Schneckenstirnradgetriebemotoren Although preferred, but any other drives are possible, for example, hydraulic or pneumatic drives with the interposition of timing belt or other gearboxes.

Claims (14)

1. Gripper for transporting containers (6) arranged in vertical orientation, comprising

   - a gripper cross member (1) fastened or fastenable to a lifting device,

   - two diametrically opposite support arms (3) projecting downwardly from the gripper cross member (1) and having at lower ends thereof gripper elements (4) for gripping the containers, wherein the spacing between the support arms (3) is matched to the diameter of the containers (6),

   characterised in that the gripper elements (4) are constructed for gripping below the grip surfaces (5) of the containers (6) and that two centring arms (8) - each offset by approximately 90° relative to the support arms (3) - project downwardly from the gripper cross member (1), wherein the spacing between the centring arms (8) is matched to the diameter of the containers (6).
2. Gripper according to claim 1, characterised in that the supporting and/or centring arms (3 or 8) are arranged at the gripper cross member (1) to be radially adjustable.
3. Gripper according to claim 1 or 2, characterised in that the gripper elements are constructed as catches which are each rotatable about a vertical axis extending through the associated support arm (3).
4. Gripper according to claim 3, characterised in that the catches (4) are respectively mounted in the associated support arm (3) and drivable by a vertical shaft (10) extending in the support arm (3).
5. Gripper according to claim 4, characterised in that the shafts (10) are each connected by way of a cardan joint (11) with an associated drive (12).
6. Gripper according to claim 5, characterised in that the drives are constructed as worm spur wheel gear motors (12).
7. Gripper according to claim 5 or 6, characterised in that the drives (12) are manually actuable.
8. Gripper according to any one of claims 3 to 7, characterised in that the end positions of the catches (4) are respectively defined by abutments.
9. Gripper according to any of claims 3 to 8, characterised in that the end positions of the catches (4) are respectively monitored by limit switches (13) which run in pairs on a cam disc (14) driven by the associated shaft (10).
10. Gripper according to any one of claims 3 to 9, characterised in that the dimensioning of the drive power and the transmission translation ratio produce a mechanical locking of the catches (4).
11. Gripper according to any one of claims 1 to 10, characterised in that at least one of the centring arms (8) carries at its lower end a sensor (15) which is directed radially inwardly and grips an engagement surface (5) of the containers (6).
12. Gripper according to claim 11, characterised in that the sensor is constructed as an ultrasound proximity switch (15).
13. Gripper according to any one of claims 1 to 12, characterised in that the cross member (1) carries at least one upwardly projecting pin (16) for engagement in a complementary receptacle of the lifting device.
14. Gripper according to claim 13, characterised in that two diametrically opposite pins (16) are provided.

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