US3679254A

US3679254A - Panel lift clamp assembly

Info

Publication number: US3679254A
Application number: US114762A
Authority: US
Inventors: Robert B Taylor
Original assignee: Metropolitan Industries Inc
Current assignee: Metropolitan Industries Inc
Priority date: 1971-02-12
Filing date: 1971-02-12
Publication date: 1972-07-25
Anticipated expiration: 1989-07-25

Abstract

The specification and drawings disclose a clamp assembly particularly suited for handling large construction panels, prefabricated wall sections, and the like. The structure comprises an elongated frame having a pivoted lift member connected generally at the center of one side. Extending from the opposite side of the frame are a plurality of opposed pairs of clamp plates. The clamp plates in each pair are arranged for adjusting movement toward and away from one another. Additionally, biasing means are provided to permit each plate to tilt to compensate for irregularities in a panel being clamped and lifted. Also, the biasing means function to return the clamp plates to their original position after they are disengaged from the panel.

Description

United States Patent Taylor [451 July 25,1972

[54] PANEL LIFT CLAMP ASSEMBLY [72] Inventor: Robert B. Taylor, North Canton, Ohio [73] Assignee: Metropolitan industries, Inc., Canton,

Ohio

[22] Filed: Feb. 12, 1971 [2]] Appl.No.: 114,762

Primary Examiner-Evon C. Blunk Assistant Examiner-l. Kenneth Siiverman Attorney-Fay, Sharpe & Muiholland [57] ABSTRACT The specification and drawings disclose a clamp assembly particularly suited for handling large construction panels, prefabricated wall sections, and the like. The structure comprises an elongated frame having a pivoted lift member connected generally at the center of one side. Extending from the opposite side of the frame are a plurality of opposed pairs of clamp plates. The clamp plates in each pair are arranged for adjusting movement toward and away from one another. Additionally, biasing means are provided to permit each plate to tilt to compensate for irregularities in a panel being clamped and lifted. Also, the biasing means function to return the clamp plates to their original position after they are disengaged from the panel.

13 Claims, 7 Drawing Figures mzmtnm m2 3.679.254

sum 2 or 5 INVENTOR. 05527 5. MVLOQ 7%, 3% mama PANEL LIFT CLAMP ASSEMBLY BACKGROUND OF THE INVENTION The subject invention is directed toward the material handling art and, more particularly, to an improved clamp assembly for handling large rectangular members.

The invention is particularly suited for handling prefabricated building panels such as wall and partition sections and will be described with particular reference thereto; however, as will become apparent, the invention is capable of broader application and could be used for handling many types of panels, sheet materials and the like.

In recent years, it has become increasingly common to prefabricate large building sections such as interior and exterior walls, and other large building panels in a factory or shop and transport them to the job site where they are installed. It has been found that this substantially reduces construction costs and speeds the construction process.

One of the problems with the prefabricated type of construction has been the difficulty of handling the large panels without damaging them. In many instances, their size is such that they must be lifted and moved into position by some type of power operated lifting mechanism such as a crane. Difficulties are encountered in connecting the lifting cables to the panels without causing damage to the panels. In some instances, lifting lugs and the like are built directly into the panels. Additionally, lugs, cavities, etc., usually require more expensive form work and increased steel reinforcing. This merely increases the cost of the panels and, in many instances, increases the labor involved since removal of the panel lift lugs must often be done after the panels are installed.

GENERAL DESCRIPTION OF THE INVENTION The present invention overcomes the above problems and provides a lift clamp assembly which can be used for positively gripping the panels and providing means for connection of the necessary lifting cables and the like. The clamp assembly is designed so that it compensates for any minor thickness variations, uneveness in the panel, or the like. Further, the inventive clamp structure is arranged so that it quickly adjusts to varying panel thicknesses and configurations.

In accordance with the invention, there is provided a lift clamp assembly particularly suited for handling large structural panels or the like comprising an elongated frame carrying at least a pair of clamp plate members having generally aligned and opposed clamping surfaces. Adjusting means are provided for selectively moving the clamping surface of at least one of the clamp plate members toward and away from the clamping surface of the other to grip opposed surfaces of a body positioned therebetween. Connected to the clamp plate members are biasing means which function to permit relative tilting movement between the clamping surfaces to compensate for any non-parallelism of the opposed surfaces gripped on the body and to return the gripping surface to approximate parallelism after engagement with the body.

Because of the arrangement of the clamp plates of the biasing means, the clamping surfaces can tilt or shift to mate with the panel surfaces which are not perfectly flat or parallel. Additionally, after the clamp assembly is disengaged from a panel, the clamp members automatically return to their original, generally parallel relationship for ready engagement with another panel.

In accordance with another aspect of the invention, it is contemplated that a plurality of pairs of clamp members will be carried on a single elongated frame and that a lift member will be pivotally connected to the frame generally at its midpoint. This arrangement permits the clamp assembly to be clamped to a vertical edge of a panel and the lift member pivoted to extend in a direction most convenient for attachment to a lift hook or the like.

Accordingly, a primary object of the invention is the provision of a panel lift clamp assembly which includes adjustable lifting plates or pads that can individually shift to compensate BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages will become apparent from the following description when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a side elevation of a lift clamp assembly formed in accordance with the preferred embodiment of the invention;

FIG. 2 is an elevational view showing the side of the lift clamp assembly opposite from that shown in FIG. 1;

FIG. 3 is a bottom view taken on line 3-3 of FIG. 1;

FIG. 4 is an end elevation taken on line 4-4 of FIG. 1;

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 2 and showing details of one of the clamp plate assemblies;

FIG. 6 is an elevational view showing the lift clamp assembly being used for removing a construction panel from the bed of a truck; and

FIG. 7 is an elevational view showing the lift clamp assembly being used for raising a construction panel.

DETAILED DESCRIPTION OF THE DRAWINGS opposed cooperating pairs along the length of the frame assembly l0.

FRAME ASSEMBLY 10 The frame assembly could take many forms and have a variety of different constructions; however, according to the preferred embodiment, the frame comprises a first elongated channel member 16 which, as best shown in FIG. 4, is positioned with its flanges 18 extending vertically upwardly. Connected to the flanges l8 and extending downwardly therefrom are somewhat

shorter channel sections

20 and 22. The

channel sections

20 and 22 are positioned in opposed pairs and are connected to the horizontal channel 18 in any convenient manner such as by welding. Reinforcing plates 24 are joined across the upper ends of each opposed pair of

channels

20, 22. This provides a rigid, elongated frame having a generally inverted U-shape when viewed from the end.

In order to facilitate handling and lifting, a lift hook assembly 26 is connected to the frame. Many different types of lift assemblies could be provided and connected to the main frame 10 at different points; however, according to the preferred embodiment, the lift hook assembly 26 is preferably connected to frame 10 on the line passing vertically through the assemblys center of gravity. Additionally, the hook assembly is arranged so that it can pivot relative to the frame assembly 10. In other words, the frame 10 is self-locating relative to the lift hook assembly and torque cannot be applied from the frame to the upper end of the lift assembly.

The preferred structural details of the hook assembly 26 are best shown in FIGS. 1 and 4. Specifically, the hook assembly comprises a lift member 28 formed from pipes or rod and having a tapered U-shape shown in FIG. 4. A pair of transversely extending rods or bars 30 are connected between the legs of member 28 for structural stability. The lower end of each of the legs is provided with sleeves or bearing members 32 which receive a center shaft or pivot shaft 34. It should be understood that the sleeves 32 are freely rotatable relative to the shaft 34.

The shaft 34 is positively connected to the frame assembly by being welded to the center reinforcing plate 24.

CLAMP

PLATE ASSEMBLIES

12 and 14 In the embodiment under consideration, there are three sets of

clamp plate assemblies

12 and 14 located symmetrically relative to the channel 18. As will become apparent, a greater or lesser number of pairs of these clamp assemblies could be utilized without departing from the invention. Additionally, although each of the pairs of clamp assemblies is identical, it should, of course, be understood that the details of construction of these assemblies could vary from that shown and individual pairs could be made slightly different than other pairs.

In the embodiment shown, since each pair is identical, only one pair will be described in detail. Like reference numerals will be utilized to identify corresponding parts in each pair and a description of one such part is to be taken as equally applicable to the others unless otherwise noted.

Specifically, the clamp plate assembly 12 comprises a first rectangular metal clamp plate 38 having a removable member 40 carried thereon and defining the clamping surface. The clamping surface defining member 40 is formed from any suitable material such as heavy plastic, masonite, rubber sheeting or the like and is joined or otherwise connected to the plate 38 in any convenient manner. In the embodiment under consideration, plate 40 is connected to plate 38 by a plurality of flat head machine bolts 42 which have their heads received in counter-sunk recesses formed inwardly of the outer surface. This arrangement provides a flat clamping surface which engages the panels or wall sections which are to be lifted.

Of particular importance to the invention is the mounting of the clamp plate 38 to allow it to have a freedom of movement in 2 about its center point. This allows the clamping surface to adjust to irregular panel surfaces without causing undue stress on any one point. Many different types of mountings could be used; however, in the subject embodiment, the mounting comprises four stud bolt or shaft members 44 which are welded to the back side of plate 38 and extend perpendicularly therefrom (see FIGS. 1, 3 and 4). The stud bolt members 44 are uniformly located relative to the center of plate 38. As best shown in FIGS. 1 and 3, the studs pass through plates or support bars 46 welded to the vertically extending channels 20. Openings are formed through the support bars 46 of sufficient large size so that the studs pass freely therethrough to allow tilting of the plate relative to the support bars.

The studs are maintained under a continual bias acting to draw the clamp plate 36 toward the channels 20. The biasing means comprise coil springs 48 positioned about the outer end of each stud 44 and acting between the back surface of the support bars 46 and a washer 50 held on the studs by suitable nuts 52.

In order to permit adjustment of the clamp plate 38 and move it outwardly from the channel against the bias of the coil springs 48, a threaded adjusting member is positioned to engage generally at the center of plate 38. In the embodiment under consideration, the threaded adjusting member comprises a threaded rod 60 having a handle 62 carried at its outer end. Its inner end portion is threaded as shown at 64 and passes through a nut 66 tack-welded to the back surface of the web of channel 20. The innermost end 68 of shaft 64 is rounded slightly and engages the center of plate 38. A washer or annular locating member 70 is joined to plate 38 and surrounds the end of shaft 60.

The arrangement thus far described allows adjustment of the lateral position of plate 38 while permitting it to tilt or pivot somewhat about the stud end 68. Since the studs 44 are symmetrically located relative to the end 68, the springs 48 provide a centering action on the clamp plate 38. That is, when the plate is not in engagement with'a panel or other member being lifted, it automatically assumes a position perpendicular to shaft 60.

As previously mentioned, each of the clamp plate assemblies 12 cooperates with a corresponding one of the clamp plate assemblies 14. As best shown in FIGS. 2 and 3, each clamp plate assembly 14 comprises a rectangular metal clamp plate member 76 having a sheet or plate of material 78 connected to its inner face and defining the clamping surface. The material 78 is preferably releasably connected to the plate 76 by a plurality of flat head machine bolts 80 (see FIG. 5) which have their heads received in recessed openings 82 formed in the sheet material 78.

The clamp plates 76 are mounted so as to allow limited tilting about their center points so that they can readily align with the panel being lifted or the opposed clamp plate 38. For this reason, a stud member 84 is welded to the center of the rear surface of plate 76 and extends through a somewhat larger diameter opening formed in the web of the downwardly extending channel 22. The opening through which the stud extends is, of course, sufficiently large to permit substantial tilting of the plate 76 relative to the channel 22. Additionally, a hemispherical washer or pivot member 86 is positioned about the inner end of stud 84 to provide a pivotal surface for engaging the face of the web of channel 22. The hemispherical member 86 is biased into engagement with the web by a coil spring 88 which surrounds the outer end of stud 84 and is compressed between the web of the channel and a washer 90 held on shaft or stud 84 by a nut 92. As can be appreciated, this arrangement provides for tilting and shifting adjustment of the clamping surface of assembly 14.

In order to assure that the clamp plates 76 return to proper alignment after disengagement from a panel member, the three clamp plates 76 are resiliently interconnected and biased in the manner best shown in FIGS. 2 and 3. Note that coil springs 94 are connected between adjacent clamp plates 76. The coil springs 94 are connected to the plates under tension with a pair of the springs located between each adjacent pair of clamp plates 76. The locations of the connections for the coil springs are equidistant from the horizontal and vertical center lines through the center of the individual clamp plates. Consequently, after the clamp assemblies have been released, the springs 94 act to return the plates the horizontal and vertical alignment. This is because the springs move the plate to equalize the force or tension being applied by each and thus return the plates to their original positions.

While it is apparent from the drawings and the above description, it should be stated clearly, the combination of

springs

48, 88 and 94 act together to maintain the mouth of the clamp in wide open to facilitate easy insertion of a panel. The automatic self-aligning features speed the operation considerably.

Referring to FIGS. 6 and 7, the use of the clamp panel lifting assembly to perform one type of lifting operation is illustrated. Note that a wall panel or the like is shown lying in a horizontal position on the back of a truck 102 shown in phantom lines. The lift clamp assembly is, in this instance, connected to the vertical end edge of the panel 100 since the panel is to be moved to stand at a ninety degree relationship from the position in which it is delivered. In connecting the clamp assembly, the assembly is opened to a width sufficient to freely pass onto the panel and, thereafter, the handles 62 are manually rotated to tighten the clamp plates 38 into en gagement with the one surface of the panel and draw the clamp plates 76 into engagement with the opposite surface. The previously mentioned centering arrangements allow the clamp plates to adjust to any slight irregularities or non-parallelism of the surfaces of the panel and prevent undue forces from being applied at any point on the panel. With the clamp assembly firmly attached to the end of the panel, the lift hook assembly is pivoted to a position where it can be readily connected to the lifting cables or hooks (a lift hook 104 is shown carried on the end of a crane 106). Although not previously mentioned, the length of the lift hook assembly is preferably long enough so that it extends beyond the outer end of the frame 10 so that connection can be made without damage to the panel. After the lift hook has been properly connected, a

vertical lift of the hook causes the panel to be pivoted about and move to a vertically extending position as shown in FIG. 7.

The invention has been described in great detail sufficient to enable one of ordinary skill in the clamp art to make and use the same. Obviously, modifications and alterations of the preferred embodiment will occur upon a reading and understanding of the specification and it is my intention to include all such modifications and alterations as part of my invention insofar as they come within the scope of the appended claims.

What is claimed is:

l. A lift clamp assembly for use in handling large panels or the like bodies comprising:

a. an elongated frame;

b. at least two pairs of clamp plate members depending from said frame and having generally aligned and opposed clamping surfaces;

c. adjusting means for selectively moving the clamping surface of at least one of said clamp plate members toward and away from the clamping surface of the other to grip opposed surfaces of a body positioned therebetween; and,

d. biasing means connected to each of said clamp plate members for permitting relative movement between said clamping surfaces to compensate for non-parallelism of the opposed surfaces gripped on the body and to return said gripping surfaces to approximate parallelism after disengagement from the body, said biasing means including springs connected between adjacent clamp plates.

2. The lift clamp assembly defined in claim 1 wherein said adjusting means comprise a threaded member positioned to engage one of said clamp plate members on the side opposite its clamping surface and wherein said biasing means include a plurality of springs located about said threaded member.

3. The lift clamp assembly as defined in claim 1 including a lift member connected to said frame at a location generally intermediate said lift plates.

4. The lift clamp assembly as defined in claim 1 wherein said clamp assemblies are each independently adjustable and wherein said biasing means further include springs located uniformly about said adjusting means.

5. The lift clamp assembly as defined in claim 1 including a lift member connected to said frame, said lift member being pivotally connected to said frame generally at the center thereof.

6. The lift clamp assembly as defined in claim 5 wherein said lift member has a length greater than one-half the length of said frame.

7. A lift clamp assembly including: a frame carrying at least a pair of opposed first and second clamp plate members having aligned clamping surfaces;

adjusting means for varying the spacing between said clamping surfaces and including a movable member engaging the first clamp plate on the side opposite its clamping surface;

first biasing means biasing said first clamp member into engagement with said movable member for maintaining said plate in engagement therewith while permitting it to tilt relative thereto; and,

said second plate member being pivotally connected to said frame and second biasing means for maintaining said second plate member biased toward said frame while permitting tilting relative to said frame,

said second clamp plate being connected to said frame by a stud member which extends through said frame, said stud member carrying a hemispherical surface which engages said frame; and, wherein said second biasing means includes means for maintaining said hemispherical surface biased into engagement with said frame.

8. The lift clamp assembly as defined in claim 7 wherein said first biasing means comprise a plurality of springs positioned about said movable member.

9. The lift clamp assembly defined in claim 8 including at least two pairs of said clamp plate members carried at longitudinallyTslpaced points on said frame.

10. e lift clamp assembly of claim 7 including a second pair of said first and second clamp plate members carried by said frame at locations spaced from said first pair.

11. The lift clamp assembly as defined in claim 10 wherein said second biasing means include springs interconnecting the second clamp plates of each pair.

12. The lift clamp assembly as defined in claim 7 wherein said clamp assemblies are each independently adjustable and wherein said biasing means further include springs located uniformly about said adjusting means.

13. The lift clamp assembly as defined in claim 9 including a lift member connected to said frame, said lift member being pivotally connected to said frame generally at the center thereof.

Claims

1. A lift clamp assembly for use in handling large panels or the like bodies comprising: a. an elongated frame; b. at least two pairs of clamp plate members depending from said frame and having generally aligned and opposed clamping surfaces; c. adjusting means for selectively moving the clamping surface of at least one of said clamp plate members toward and away from the clamping surface of the other to grip opposed surfaces of a body positioned therebetween; and, d. biasing means connected to each of said clamp plate members for permitting relative movement between said clamping surfaces to compensate for non-parallelism of the opposed surfaces gripped on the body and to return said gripping surfaces to approximate parallelism after disengagement from the body, said biasing means including springs connected between adjacent clamp plates.

7. A lift clamp assembly including: a frame carrying at least a pair of opposed first and second clamp plate members having aligned clamping surfaces; adjusting means for varying the spacing between said clamping surfaces and including a movable member engaging the first clamp plate on the side opposite its clamping surface; first biasing means biasing said first clamp member into engagement with said movable member for maintaining said plate in engagement therewith while permitting it to tilt relative thereto; and, said second plate member being pivotally connected to said frame and second biasing means for maintaining said second plate member biased toward said frame while permitting tilting relative to said frame, said second clamp plate being connected to said frame by a stud member which extends through said frame, said stud member carrying a hemispherical surface which engages said frame; and, wherein said second biasing means includes means for maintaining said hemispherical surface biased into engagement with said frame.

9. The lift clamp assembly defined in claim 8 including at least two pairs of said clamp plate members carried at longitudinally spaced points on said frame.

10. The lift clamp assembly of claim 7 including a second pair of said first and second clamp plate members carried by said frame at locations spaced from said first pair.