Gripper For Handling Heavy Products And Specifically Horizontal-axis Coils

Abstract

In a handling gripper for rigid products and specially coils there is provided a framework in the form of a rigid casing pivotally suspended from a vertical suspension pivot attached to a lifting hook. The casing houses horizontal telescopic arms operated by a horizontal ram and from which are suspended hollow vertical telescopic grasping arms each housing a vertical hydraulic ram connected to a compressed oil accumulator which supplies oil to said horizontal ram and to a rotating ram about the vertical suspension pivot, according to the position of a remotely controlled electromagnetic valve.

Description

The present invention relates to a gripper intended for handling packages of metal plates and above all coils of sheet metal having their axis positioned horizontally.

To perform this handling action, grippers are employed which comprise a strong framework supporting vertical grasping arms which may be opened or closed in manner to bring claws tipping these arms to grasp or release the product to be displaced. In the known grippers, the opening and closing of the arms are produced by a variety of devices, commonly by electrical actuation or by means of a motor-reduction gear. Owing to this fact, the actuating means have given speeds imposed a priori, so that impacts occur at some instants, which are difficult to prevent even if the operative works with care and smoothly. The vertical grasping arms thus strike suddenly against the product to be lifted, which is particularly inconvenient in the case of acoil of metal sheets, whereof the edges are easily dented at some points ; the cables for lifting the gripper by means of the travelling crane also incur shocks, which acts deleteriously on their durability; the floor covering on which the product carried by the gripper is placed too roughly, deteriorates quickly. Moreover, another major shortcoming of the known grippers consists in their excessive bulk given their considerable dimensions in height as well as in length. This considerable bulk limits the storage capacity in a store ; in point of fact, in the vertical direction, it is necessary to keep an unobstructed height above a store of coils equal to the height for passage of the travelling or overhead crane plus the height of the gripper ; moreover, the the rows of coils should be spaced apart sufficiently to allow the gripper to come down between two adjacent rows of considerable height to grasp coils situated in a lower row.

The present invention which has the object of eliminating the shortcomings cited, relates to a handling gripper for heavy products and specifically to sheet metal coils having their axes positioned horizontally, comprising a strong framework equipped with horizontal arms, which are displaceable and terminally carry vertical grasping arms, being characterised in that it comprises suspended in rotary manner from a vertical suspension pivot carried by an attachment for fastening to a lifting hook, a frame formed by a rigid case in which are housed horizontally telescopic arms from which are suspended vertical telescopic grasping arms , in each of which is housed a hydraulic ram or jack in communication with a pressurised oil accumulator which, according to the position of remote control electromagnetic valves, feeds a ram for actuation of the horizontal telescopic arms and a ram for rotation of the gripper, the said rams both being connected to a reserve tank containing oil under pressure, connected to the rams of the vertical grasping arms in such manner as to accumulate a part of the potential energy of the load handled to induce operation of the gripper independently of any source of energy external to the gripper-load aggregate.

According to one feature, the rigid case is a hollow element of double T-shape in plan view whereof the branches contain the horizontal telescopic arms whereas the stem is secured in rotary manner to the vertical suspension pivot.

According to another feature, the horizontal telescopic arms are each formed by two elements, an internal element remaining close to the suspension spindle and an external one spaced apart from the said spindle in the extended position, and installed telescopically with respect to each other and to the rigid case.

According to another feature, the internal telescopic elements of each arm each carry, at one side, a rack meshing with a pinion arranged loose on the vertical pivot and, at the other side, a pinion meshing on the one hand with a rack arranged on the rigid case, and on the other hand with a rack arranged on the external telescopic elements.

Other features of the invention will become more clearly apparent from the following description of the accompanying drawings which relate to an example of embodiment given by way of illustration only.

In these drawings :

FIG. 1 is a diagrammatical view in lateral elevation of a gripper wrought according to the invention.

FIG. 2 is a view in axial section along II--II of FIG. 1.

FIG. 3 is a view in section along III--III of FIG. 1.

FIG. 4 is a view in section along IV--IV of FIG. 1.

FIGS. 5 and 6 are respectively fragmentary side cross-sectional and plan views of the rotation ram structure according to the present invention.

These figures show only the elements useful in grasping the invention, the others having been omitted deliberately.

The gripper in question comprises a rigid framework formed by a hollow case 5 having a form of double T-shape in plan view. This hollow case 5 is equipped with a ball thrust bearing 8 traversed by a vertical suspension pivot 7 which is guided in a bushing 9 integral with the said case. The upper part of this vertical pivot 7 passes through a horizontal securing pivot 4 and is equipped with a retaining nut 7a. The horizontal pivot 4 forms a lower spacer or cross-member of a fastening attachment which is formed by two flat elements 3 also stayed at the upper part by a removable securing bar, 1 equipped with a removable sleeve or socket 2 "taken" by a lifting hook which is not shown. In this way, the sleeve 2 can be changed, so that the latter can thus be matched to the radius of curvature of the lifting hook, preventing accidental unhooking.

In the branches of the hollow rigid case 5 situated at either side of the vertical pivot 7 are housed horizontal telescopic arms, each formed by an internal telescopic elements 10 of casing form, and by an external telescopic element 14. The two internal telescopic elements 10 which slide in slideways 11 situated in the case 5 are displaced synchronously by means of a gear 12 meshing with a rack 10a on each element 10 ; this gear 12 runs loose in a bushing 13 situated on the vertical pivot 7. The displacement of the said elements 10 is produced by a single hydraulic actuating ram 20 having a joint 21 for fastening to the case 5 and whereof the end of the rod 22a of the piston 22 is jointedly coupled to a lug 22 integral with the adjacent telescopic element 10.

In the telescopic elements 10 of casing form are arranged slideways 15 in which there slide the external telescopic elements 14 ; however, each of the said elements 10 possesses lugs 17a in which are situated bearings 17 of a pivot 17b for support of a pinion 16 which meshes on the one hand with a rack 18 secured to the case 5, and on the other hand with a rack 19 secured to the external horizontal telescopic element 14. Thus by actuation of the control ram 20, the displacement is caused of the elements 10 and 14 in one direction or the other, the elements 14 being displaced at twice the speed of that of the elements 10.

To the free extremity of each of the elements 14 is secured a vertical grasping arm 6. Each of the two vertical arms 6 consists of a fixed part 23 integral with an element 14 ; on these fixed parts 23 slide sleeves 24 each terminating in a grasping claw 25 which is equipped with a removable bearer element 25a. This element is removable to allow of easy replacement in case of wear, or of the application of longer elements penetrating more deeply into the coil, or of pivoting elements reducing the thickness of the sleeves 24 as much as possible.

To the lower extremity of the fixed elements 23 are jointedly coupled at 28 hydraulic rams 26 whereof the piston has a rod 26a whose upper extremity has a joint 26b for coupling to the sleeves 24 ; to ensure guiding of these sleeves 24 on the elements 23, provision is made to equip these latter with ball races 27 which roll in grooves 24a machined in the inner face of the sleeves 24.

On the hollow case 5 are fastened a pressurized oil accumulator 31 and an oleopneumatic tank 32, in which the oil is subjected beforehand to an air pressure of the order of 6 kgs/cm.sup.2.

When it is intended to lift a coil with the gripper, the latter is brought to the appropriate spot by means of an overhead crane which is not shown, after which a radio-electric signal is applied for operation by means of a battery, of a reception set 36, an electromagnetic valve 35, and through a pipe 20a starting from the accumulator 31 and by means of the electromagnetic valve 35, and through a pipe 20c , the ram 20 is supplied to spread the arms 6, then through a pipe 20b to close the said arms 6 and tighten the gripper on the coil. The coil grasped is then raised and the sleeves 24 initially descend relative to the fixed parts 23 of the arms of the gripper, so that the oil of the rams 26 enclosed within the compression chambers between the piston and bottom of each cylinder of the said rams 26 is compressed and expelled under pressure into the oleopneumatic accumulator 31 by passing through pipes 29 in each of which is installed a check valve 30. Thanks to this valve, the oil in the accumulator 31 is maintained under pressure even when the coil is set down at the point of arrival. During this last operation, the parts 23 descend in the sleeves 24 and oil coming from the tank 32 re-enters the compression chambers of the rams 26, passing through a pipe 32a and a check valve 33. A radio-electric signal transmitted to the receiver of the set 36 is then applied to actuate the electromagnetic valve 35 and cause the accumulator 31 to feed the ram 20 through the pipes 20a,20c to open the gripper and thus release the coil. The ram 20 for the opening and closing of the gripper is actuated by the oil from the accumulator 31 and is connected at its two ends to the tank 32 through the electromagnetic valve 35 and the pipe 35a so that the oil expelled from the said ram re-enters this tank 32.

In analogous manner, and again by means of a radio-electric signal transmitted to the receiver of the set 36, an electromagnetic valve 37 is actuated which allows oil to pass through a pipe 37a from the accumulator 31 into a ram 34 for actuation of the rotation of the gripper around the vertical suspension pivot 7, the oil issuing from this ram re-entering the tank 32 through 34a.

As seen in FIGS. 5 and 6, the rotation ram 34 is carried by a bracket 42 on hollow case 5 and comprises a piston 40 whose rod is attached to a rack 41 which engages with a pinion 38 mounted on a shaft 39 carried by case 5. Upon feeding hydraulic fluid to the ram 34 on one side or the other of the piston 40, the piston moves in one direction or the other and moves the rack 41 in one direction or the other so that the pinion 38 turns in one direction or the other, which in turn rotates the case 5 and the entire gripper in one direction or the other.

A gripper like that described is advantageous in several respects. First of all, it operates without an external source of energy, to open, close and rotate in both directions, which renders it possible to omit a winder with a supply cable. Its very structure ensures that its bulk is reduced in length as well as in height.

Claims

I claim:

1. Handling gripper for rigid products such as coils having a horizontal axis, comprising a framework formed by a rigid hollow casing of a double T-shaped form, a fastening attachment to a lifting hook, a vertical suspension pivot carried by said fastening attachment and passing through a ball thrust bearing carried by said rigid hollow casing, horizontally telescopic arms housed in said hollow casing having two elements telescopic relative one to the other and relative to said hollow casing, vertical telescopic grasping arms suspended from the ends of said horizontally telescopic arms, a vertical hydraulic ram housed in each said vertical telescopic grasping arm, an oil accumulator receiving compressed oil from said vertical hydraulic ram, each said vertical arm having parts movable relative to each other when a load is lifted by said gripper, said relatively movable parts actuating said rams to send oil to said accumulator so as to recover a part of the potential energy of the handled load, a reserve tank containing oil under pressure, a horizontal hydraulic ram acting between said framework and one of said horizontally telescopic arms, means for supplying compressed oil from said accumulator to said horizontal hydraulic ram for actuating said horizontally telescopic arms, a rotating ram and means for supplying said rotating ram with compressed oil from said accumulator for rotating the gripper about said vertical suspension pivot.

2. Handling gripper according to claim 1 in which each vertical telescopic grasping arm comprises a fixed part unitary with the horizontally telescopic arms and on which is located a sliding sleeve terminating in a grasping nose for a coil, a vertical hydraulic ram being connected to said fixed part and to said sliding sleeve.

3. Handling gripper according to claim 2, in which said sleeve has longitudinal grooves in which roll ball races carried by said fixed part.