US3771666A

US3771666A - Load grab mechanism having separable rotatable grab arms

Info

Publication number: US3771666A
Application number: US00268143A
Authority: US
Inventors: O Fournier
Original assignee: Harnischfeger Corp
Current assignee: Harnischfeger Corp
Priority date: 1972-06-30
Filing date: 1972-06-30
Publication date: 1973-11-13
Anticipated expiration: 1990-11-13

Abstract

A load grab mechanism for use on a material handling device such as a stacker crane to handle heavy loads having a central opening (such as coils of sheet metal) comprises a support on which a horizontally disposed splined shaft is mounted for rotation by a pair of hydraulic actuators. A pair or grapple arms are mounted on the splined shaft and are slidably movable by another pair of hydraulic actuators to juxtaposed or separated positions. The grapple arms are movable to horizontal or vertical positions by rotation of the splined shaft. A stop block rigidly mounted on the support engages the grapple arms when they are in juxtaposed or partly separated horizontal position to prevent their downward rotation when subjected to a load. In operation, the grapple arms (in either horizontal or vertical position) can engage the ends of the central opening of a horizontally disposed coil. The grapple arms (in horizontal position and juxtaposed) can be inserted into one end of the coil opening. The crane is then operated to move the load to a desired location; whereupon the grapple arms are moved to release the load.

Description

United States Patent [191 Fournier Nov. 13, 1973 LOAD GRAB MECHANISM HAVING SEPARABLE ROTATABLE GRAB ARMS [52] US. Cl. 212/21, 2'12/127, 294/103 CG [51] Int. Cl. B66c 17/06, B66c 1/42 [58] Field of Search 212/11, 127, 128, 212/129,125,126, 21; 294/67 C, 67 BB, 103

[56] References Cited UNITED STATES PATENTS 9/1971 Martelee 294/103 CG X 5/1966 Dechantstreiter 212/21 3,104,016 9/1963 Harry 212/129 3,247,974 4/1966 Dechantsreiter 212/11 FOREIGN PATENTS OR APPLICATIONS 696,581 9/1953 Great Britain 212/11 Primary Exizminer-Robert S. Ward, Jr. Att0rney--James E. Nilles [57] ABSTRACT A load grab mechanism for use on a material handling device such as a stacker crane to handle heavy loads having a central opening (such as coils of sheet metal) comprises a support on which a horizontally disposed splined shaft is mounted for rotation by a pair of hydraulic actuators. A pair or grapple arms are mounted on the splined shaft and are slidably movable by another pair of hydraulic actuators to juxtaposed or separated positions. The grapple arms are movable to horizontal or vertical positions by rotation of the splined shaft. A stop block rigidly mounted on the support engages the grapple arms when they are in juxtaposed or partly separated horizontal position to prevent their downward rotation when subjected to a load. In operation, the grapple arms (in either horizontal or vertical position) can engage the ends of the central opening of a horizontally disposed coil. The grapple arms (in horizontal position and juxtaposed) can be inserted into one end oi the coil opening. The crane is then operated to move the load to a desired location; whereupon the grapple arms are moved to release the load.

15 Claims, 9 Drawing Figures PAIENIEB 1m 1 3 ms SHEET 1 BF 1 FIG. 1

PAIENIEMuv 1 3 ms 3771.666

FIG.9

LOAD GRAB MECHANISM HAVING SEPARABLE ROTATABLE GRAB ARMS BACKGROUND OF THE INVENTION 1. Field of Use This invention relates generally to load grab mechanisms for use on material handling devices, such as stacker cranes or the like, and particularly to such mechanisms having a pair of separable grapple arms which can be rotated between horizontal and vertical positions to conveniently engage a load.

2. Description of the Prior Art Some stacker cranes, for example, employ a vertically telescoping downwardly depending rotatable mast which has suitable load grapple means at the lower end thereof. US. Pat. No. 3,250,399 issued May 10, 1966, to M. Dechantsreiter for Stacker Crane and assigned to the same assignee as the present application discloses an example of such a crane. Such cranes also sometimes have an independently suspended and vertically adjustable operators cab. When such cranes are regularly applied to handling loads of a particular size or shape, and especially loads of unusual shape, crane op-' erations can be greatly expedited if the load grapple means are especially adapted to suit the type of load involved. For example, in steel mill operations sheet metal coils weighing up to 30 tons are usually transported in gondola-type railroad cars closely packed and with the coil openings horizontal. Because of this, con-' ventional stacker cranes cannot be used to load or unload such coils because the crane carriage collides with the sides of the gondola car or adjacent coils. And, since the cylindrical outer surface of the coils offers little purchase for conventional load grapple means, it

was the practice heretofore to use a sling looped through the coil opening and attached to a crane hook to load and unload such coils. This required the services of an extra laborer to attach and detach the sling and was costly, time-consuming, and dangerous.

SUMMARY OF THE PRESENT INVENTION In accordance with the present invention there is provided an improved load grab mechanism for use on material handling devices such as stacker cranes which is especially well-adapted for handling loads having a horizontally disposed central opening therein such as heavy coils of sheet metal.

The load grab mechanism comprises a rigid support structure or carriage (such as a heavy metal frame), which is connected to and movable by the crane and on which the grab mechanism components are mounted. In a preferred embodiment, the support structure is rigidly secured to the lower end of a downwardly depending vertically telescoping rotatable mast of a stacker crane, but could be applied to other types of cranes. Preferably, the crane comprisesan independently suspended and vertically adjustable operators cab. The support structure is provided with spaced apart bearings on which a horizontally disposed splined shaft is mounted for axial rotation. A pair of grapple arms are mounted on the shaft and are slidably movable thereon toward each other to a juxtaposed position and slidable away from each other to separated positions.- Each grapple arm is slidable by means of a separate hydraulic actuator which is connected between the grapple arm erate simultaneously. The shaft is rotatable, preferably 90, by means of one or more hydraulic actuators which are connected between the support structure and lever arms rigidly secured to the shaft so as to move the grapple arms to horizontal or vertical positions. Stop means, in the form of a rigid block or member rigidly secured to the support structure just above the position of the grapple arms when the latter are juxtaposed, engage the upper surfaces of the grapple arms when the latter are nearly or completely juxtaposed and extended horizontally (by rotation of the splined shaft) to prevent downward rotation of the arms (and shaft) when subjected to a load and to transfer load forces to the support structure. Consequently, none of the hydraulic actuators are subjected to such load forces but only to the weight of the grab mechanism components.

In operation, the grapple arms need to be separated sufficiently far so as to be clear of the stop means and then they can be rotated to horizontal or vertical position, depending on clearance and on the orientation or physical location of the coil or other load to be lifted. For example, if the coil opening is horizontal, the coil may be lifted in several ways. First, the grapple arms may be vertically disposed and widely separated so that when brought together the grapple arms engage opposite ends of the coil opening. Second, the grapple arms may be horizontally disposed and then juxtaposed from horizontal insertion into one end of the opening, after which they may be separated to tightly engage the coil. Third, if the horizontally disposed coil is narrow enough, the grapple arms may be horizontally disposed and engaged with opposite ends of the coil opening; but the grapple arms must be beneath the stop means on the support structure. On the other hand, if the coil opening is vertical, the grapple arms can be vertically disposed and then juxtaposed for vertical insertion into one (upper) end of the opening. After such vertical insertion the grapple arms are separated so as to tightly engage the sides of the opening. The latter method is usable only on relatively light loads. After the grapple arms are securely engaged with the coil, the coil can be lifted and transported by raising and suitably moving the support structure of the load grab mechanism by normal crane operation.

DRAWINGS I along line 3-' 3 of FIG. 1;

Preferably, the actuators for the two grapple arm's op- FIG. 4 is an enlarged isometric view of the load grapple means shown in FIGS. 1 and 3;

FIG. 5 is a side view of-the grapple means showing its grapple arms in horizontal position and inserted in an opening in a coil of sheet metal;

FIG. 6 is a side view of the grapple means showing the grapple arms in horizontal position and grasping the ends of a coil; 1

FIG. 7 is a side view of the grapple means showing the grapple arms in vertical position and inserted in the opening in a coil FIG. 8 is a top view of the grapple means taken on line 88 of FIG. 4; and

FIG. 9 is an elementary diagram of a hydraulic control circuit for hydraulic actuators used in the grapple means.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGS. 1 and 2 of the drawings, a stacker crane in accordance with the invention has a large, rigid frame F that comprises two transverse main girders 5, 6 and two longitudinal cross beams 7 and 8. The legs, girders and cross beams are all rigidly welded or otherwise secured together to form a single, rigid mobile frame having four track engaging drive wheel means 10 near the corners of the frame. These track engaging wheels 10 are flanged wheels 8 which travel on overhead. tracks 12. I

The drive for the crane is conventional and comprises drive means for at least two drive wheels 10. For example, a squirrel cage electric motor M (only one shown) drives through speed reducers l3 and shafts 14 to the wheels 10.

The crane also has a transversely movable trolley T, which moves along

tracks

16 and 17 that extend adjacent along and are secured to the girders 5 and 6, respectively. More particularly, the trolley has four flanged wheels 19 which ride on and are guided by the

tracks

16 and 17.

The drive for the trolley takes the form of conventional electric motors 21 with conventional electricalmechanical brakes (not shown) which drive the wheels 19 in a conventional manner. The trolley can move in either transverse direction across the crane in the conventional manner.

A rotatable turret 35 is mounted on the upper side of the trolley by six wheels 36 which ride on and are guided by a circular track 37 secured to the upper side of the trolley T. Six side thrust rollers 37a (FIG. 2) are mounted on vertical axes on the turret and bear against the inner vertical side of the circular track 37 which forms part of the trolley. This construction insures that the turret remains concentric on the trolley circle and sidewise shifting of the turret cannot occur.

The turret 35 is rotated by an electric motor 47 which is carried by the trolley. The motor can be rotated in either direction to rotate turret 35 selectively in either direction to any degree. Suitable and conventional limit switches prevent over-travel and rotational speed may be in the order of 1 rpm.

A vertical mast 50 is rigidly secured to and extends downwardly from the turret 35. This mast is of rectangular cross-sectional shape and is of telescoping construction. The mast includes a relatively short upper section 51 which is rigidly secured as by welding to the turret. An intermediate section 52 is vertically slideable within section 51, and a third or lower section 53 in turn is vertically slideable within the intermediate section. Thus, a considerable range of vertical extension and contraction of the mast is possible. Due to the relatively large cross section of the mast and its rectangular form, no swaying or twisting of the mast or its load can occur. Telescoping operations of mast 50 are effected by a 'motor 42 and suitable hoist mechanism 43 supported on turret 35.

An operators cab 64 is suspended by a mast 55 from turret 35 and is vertically or telescopically adjustable independently of mast 50, as shown, for example, in US. Pat. No. 3,250,399 hereinbefore referred to.

As FIG. 1 shows, grapple means 60 in accordance with the invention is provided at the lower end of mast 50 and comprises, as FIGS. 1, 3, 4 and 8 show, a rigid supporting structure, such as a frame or carriage 62 fabricated of heavy duty steel component parts. Frame 62 is provided with spaced apart bearing

support brackets

65 and 66 on which

bearings

67 and 68, respectively, are mounted. The

bearings

67 and 68 afford support for a horizontally disposed rotatable splined shaft 70. A pair of grapple

arms

71 and 72 are slidably mounted on shaft 70. The grapple

arms

71 and 72 are provided with

splined holes

73 and 74, respectively, near their ends which enable them to be axially slidable on shaft but prevent rotation of the arms with respect to the shaft. As FIG. 4 shows, the inner surfaces of the

grapple arm

71 and 72 are provided with recesses or

cutout portions

76 and 78, respectively, and with inwardly extending

projections

79 and 80, respectively.

Means, such as two hydraulic actuators 82 almost vertically disposed are provided to rotate shaft 70 (when the grapple

arms

71 and 72 are separated beyond the ends of a stop block 100 hereinafter described) so that the grapple

arms

71 and 72 can be moved to a downwardly or vertically extending position (shown in FIGS. 1, 3 and 7) or to a horizontally extending position (shown in FIGS. 4, 5 and 6). As FIG. 3

shows, one end of the cylinder of each actuator 82 is pivotably connected by a pin 83 to a bracket 84 rigidly secured to frame 62. One end of the piston rod of each actuator 82 is pivotably connected by a pin 83 to a bracket 84 rigidly secured to frame 62. One end of the piston rod of each actuator 82 is pivotably connected by a pin 85 to a lever arm 86 which is rigidly secured on splined shaft 70. Two such lever arms 86 are provided on shaft 70 and are rigidly secured thereon as by bolts 87 shown in FIG. 8.

Means, suchas two horizontally disposed

hydraulic actuators

90 and 91, are provided to effect axial movement of the grapple

arms

72 and 71, respectively, so that the latter may be moved together to juxtaposed position (shown in FIG. 4) or moved to separated positions (as shown, for example, in FIG. 1). As FIG. 8 shows, one end of the cylinder of actuator 90 is rigidly connected to one arm 86 rigidly secured on spline shaft 70. One end of the piston rod of actuator 90 extends past grapple arm 71 and is secured to grapple arm 72. This arrangement enables actuator 90 to effect axial movement of grapple arm 72 while allowing for rotational movement of the grapple arm caused by rotation of shaft 70. FIG. 8 also shows that one end of the cylinder of actuator 91 is rigidly connected to the other arm 86 rigidly secured on spline shaft 70. One end of the piston rod of actuator 91 extends past grapple arm 72 and is secured to grapple arm 71. This enables actuator 91 to move grapple arm 71 axially while still allowing for rotational movement of the grapple arm. Holes 92 in arms 71 and 72'accommodate the

actuators

90 and 91, as FIG. 8 shows. It is within the scope of the present invention that the

hydraulic actuator

90 and 91 could be secured and connected in ways other than that shown.

In operation, both

hydraulic actuators

90 and 91 are operated simultaneously and in the same relative direction (i.e., extend or retract) it being apparent that they are shown oppositely disposed with respect to each other.

P16. 9 is an elementary diagram of a hydraulic circuit for operating the

hydraulic actuators

90, 91 and 82 and shows that all are supplied from a common fluid reservoir 94 by means of a common motor driven pump 95 through sutiable three-position (extend, neutral, retract)

hydraulic operating valves

96 and 97 respectively, which are arranged in a conventional manner. In normal operation, actuators 82 for rotating the grapple arms are preferably not operated while the

actuators

90 and 91 are being operated. The hydraulic circuit includes conventional strainers, 106, a relief valve 107, four check valves 108 to prevent cylinder movement until the control valves are operated, four springloaded balancer valves 109 for cooperation with the check valves, and flow control compensators 110. I

Stop means, in the form of a metal block 100 which is rigidly secured as by welding to frame 62, is provided to prevent downward rotation of the grapple arms 71 and 72 (and shaft 70) when they are subjected to a load and are either juxtaposed or only slightly spaced apart. Block 100 is located on frame 62 just above the upper surfaces of the inner ends of the grapple

arms

71 and 72 and is engageable thereby when the arms are horizontally disposed, as FIGS. 4, 5 and 6 show. By this means, downward forces on the grapple

arms

71 and 72 are transmitted to frame 62 and, therefore, are not imposed on the hydraulic actuators 82 which effect rotation of shaft 70. However, because of the location and length of block 100, the grapple

arms

71 and 72 cannot be rotated by the hydraulic actuators 82 to desired operating positions unless they are first separated an appropriate distance by the

actuators

90 and 91 to positions beyond the ends of block 100.

OPERATION As is apparent, grapple means 60 is movable to a desired location with respect to a load, suchas a coil 102, by appropriate movement of the crane and the mast 50 thereof.

If the coil 102 to be lifted is disposed so that its central opening 104 is horizontal, the grapple means 60 may be employed in three ways: either as shown in FIGS. 1 and 3 (i.e., with the grapple

arms

71 and 72 vertical, widely separated and engaging opposite ends of the opening 104 of the coil 102) or as shown in FIG. 5 (i.e., with the grapple

arms

71 and 72 horizontal, juxtaposed and inserted into one end of the opening 104 in the coil 102) or as shown in FIG. 6 (i.e., with the grapple

arms

71 and 72 horizontal, separated and engaging opposite ends of the opening 103 of the coil 102). Usage in accordance with FIG. 6 is only feasible if the coil to be lifted is relatively narrow, i.e., narrower than the length of the stop block 100, so that the grapple arms at least partially engage the undersurface of the stop block and transfer forces thereto.

If the coil 102 to be lifted is disposed so that its central opening 104 is vertical, the grapple means 60 may be employed as shown in FIG. 7 (i.e., with the grapple

arms

71 and 72 vertical, juxtaposed to enable insertion in the opening 104 of the coil 102, and subsequently separated so as to tightly engage the sides of the opening 104 so that the coil can be lifted.) Usage of grapple means 60 in' accordance with FIG. 7 is only feasible with relatively light loads wherein sufficient frictional engagement is possible between the exterior sides of the grapple

arms

71 and 72 and the side walls which define the opening in a load. Normally, however, usage in accordance with FIG. 7 would not be suited for lifting extremely heavy coils.

After a coil has been transported to a desired location and positioned thereat, the grapple

arms

71 and 72 are disengaged therefrom by appropriate opening or closing and withdrawal movement.

While the load grab mechanism disclosed herein is shown as employed hydraulic actuators and controls to effect rotation of shaft and sliding movement of the grapple

arms

71 and 72, it is apparent that electrical or pneumatic motors and appropriate controls could be employed instead.

I claim:

1. A crane having grapple means for engaging a load to be moved comprising: a support mounted on said crane, a shaft rotatably mounted on said support, a pair of grapple arms mounted on said shaft and rotatable therewith to raised or lowered positions, at least one of which is slidable thereon, first means selectively operable to rotate said shaft to move said grapple arms to raised or lowered positions, second means selectively operable to slide at least one grapple arm to juxtaposed and separated positions on said shaft with respect to the other grapple arm, and stop means on said support engageable with said grapple arms when the latter are in raised juxtaposed position to prevent downward rotation of said grapple arms and to transfer forces on said grapple arms to said support.

2. A crane according to claim 1 wherein said first means comprises at least one first actuator mounted on said support and connectedto rotate said shaft; and wherein said second means comprises at least one other actuator connected to at least said one grapple arm to slide the grapple arm on said shaft.

3. A crane according to claim 2 wherein said stop means comprises a member rigidly secured on said support above said grapple arms.

4. A crane according to claim 3 wherein each grapple arm is provided on the inner surface thereof with inwardly projecting means for engagement with a load.

5. A crane according to claim 3 wherein said shaft is a splined shaft and is accommodatd by correspondingly shaped holes in said grapple arms.

6. A crane according to claim 5 wherein said other actuator is horizontally disposed and wherein said first actuator is transversely disposed with respect to said other actuator.

7. A crane according to claim 6 wherein said other actuator is connected to operate that grapple arm which is most remote therefrom.

8. A crane according to claim 7 wherein said actuators are hydraulic actuators.

9. A crane according to claim ll comprising a vertically telescoping downwardly depending rotatable mast on which the support of said grapple means is mounted.

10. A crane according to claim 9 including an independently suspended and vertically adjustable operators cab.

11. A crane comprising a vertically telescoping downwardly depending rotatable mast and grapple means mounted at the lower end of said mast,

said grapple means comprising a support,

bearing means on said support,

a horizontally disposed splined shaft rotatably mounted on said bearing means,

a pair of grapple arms, each having a splined opening, slideably mounted on said shaft and movable between juxtaposed and separated positions, first actuator means mounted on said support and connected to said shaft for rotating said shaft to move said grapple arms to raised or lowered positions, second actuator means selectively operable to move said grapple arms to juxtaposed and separated positions, and stop means on said support engagable with said grapple arms when the latter are in raised juxtaposed position to prevent downward rotation of said grapple arms and to transfer forces on said grapple arms to said support. 12. A crane according to claim 11 wherein said shaft is provided with bracket means to which said first actuator means are connected to rotate said shaft, and

wherein said actuator means are connected between said grapple arms and said bracket means.

13. A crane according to claim 12 wherein said bracket means comprises two spaced apart brackets rigidly mounted on said shaft, wherein said first actuator means comprises a pair of first actuators, each first actuator connected between said support and one of said brackets, and wherein said second actuator means comprises a pair of second actuators, each second actu ator connected between one grapple arm and one of said brackets.

14. A crane according to claim 12 including an operators cab mounted on said support of said grapple means.

15. A crane according to claim 13 wherein all of said actuators are hydraulic actuators.

Claims

2. A crane according to claim 1 wherein said first means comprises at least one first actuator mounted on said support and connected to rotate said shaft; and wherein said second means comprises at least one other actuator connected to at least said one grapple arm to slide the grapple arm on said shaft.

8. A crane according to claim 7 wherein said actuators are hydraulic actuators.

9. A crane according to claim 1 comprising a vertically telescoping downwardly depending rotatable mast on which the support of said grapple means is mounted.

10. A crane according to claim 9 including an independently suspended and vertically adjustable operator''s cab.

11. A crane comprising a vertically telescoping downwardly depending rotatable mast and grapple means mounted at the lower end of said mast, said grapple means comprising a support, bearing means on said support, a horizontally disposed splined shaft rotatably mounted on said bearing means, a pair of grapple arms, each having a splined opening, slideably mounted on said shaft and movable between juxtaposed and separated positions, first actuator means mounted on said support and connected to said shaft for rotating said shaft to move said grapple arms to raised or lowered positions, second actuator means selectively operable to move said grapple arms to juxtaposed and separated positions, and stop means on said support engagable with said grapple arms when the latter are in raised juxtaposed position to prevent downward rotation of said grapple arms and to transfer forces on said grapple arms to said support.

12. A crane according to claim 11 wherein said shaft is provided with bracket means to which said first actuator means are connected to rotate said shaft, and wherein said actuator means are connected between said grapple arms and said bracket means.

13. A crane according to claim 12 wherein said bracket means comprises two spaced apart brackets rigidly mounted on said shaft, wherein said first actuator means comprises a pair of first actuators, each first actuator connected between said support and one of said brackets, and wherein said second actuator means comprises a pair of second actuators, each second actuator connected between one grapple arm and one of said brackets.

14. A crane according to claim 12 including an operator''s cab mounted on said support of said grapple means.