WO1989000135A1

WO1989000135A1 - Slip sheet having permanently bent tab and method for making same

Info

Publication number: WO1989000135A1
Application number: PCT/US1988/002100
Authority: WO
Inventors: Leon David Etlinger
Original assignee: Baron Industries, Inc.
Priority date: 1987-06-29
Filing date: 1988-06-21
Publication date: 1989-01-12

Abstract

The invention is concerned with slip sheets (10) for use in conjunction with fork lift trucks. The slip sheet (10) of the invention has a permanently bent or elevated end or side tab (12) to allow easy access by a fork lift grabber bar to secure the tab (12) of the sheet (10). The bent tab (12) is formed by pressing indentations (14) in a sheet (10) and angled with respect to the edge of the sheet.

Description

SLIP SHEET HAVING PERMANENTLY BENT TAB AND METHOD FOR MAKING SAME

The present invention relates to a slip sheet having a permanently bent tab. The invention is also concerned with a method of making such a slip sheet and takes advantage of the memory qualities of extruded polyolefin resins.

According to the present invention there is provided a slip sheet for pulling a load positioned thereon onto the fork arms of a lift truck, characterized by a thin sheet of deformable plastic material having at least one substantially straight edge, said sheet having a series of indentation formed therein, said indentations defining the boundary of a tab which is located inwardly adjacent to said edge, and said indentations being angled with respect to said edge, with the angle of each indentation being supplementary to the angle of each adjacent indentation.

According to a further aspect of the invention there is provided a method of forming a permanently bent tab in a margin of a sheet of plastic material, characterized by pressing a series of discrete indentations into said sheet along a border between said tab and the remainder of said sheet, said indentations being angled with respect to the edge of said sheet.

According to a still further aspect of the invention there is provided a device for supporting a load, characterized by a sheet of deformable plastic material having a flat main support portion, a flap portion connected to said flat main support portion by an elongated transverse hinge portion, said flap portion being outwardly inclined relative to said main support portion; and said hinge portion comprising a uniform continuous pattern of equal size and equally spaced indentations formed in said plastic material.

In order that the invention may be more clearly understood and readily carried into effect, reference will now be made to the accompanying drawings, in which

FIG. 1 is a'top view of a slip sheet embodying the features of the present invention.

FIG. 2 is a perspective view of the slip sheet of FIG. 1.

FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1.

FIG. 4 is a plan view of another embodiment of the invention. FIG. 5 is a plan view of yet another embodiment of the invention.

FIG. 6 is a detail view, at an enlarged scale, of a portion of FIG. 1.

FIG. 7 is a detail view, at an enlarged scale, of a portion of FIG. 3.

FIG. 8 is a detail view, at an enlarged scale, of a portion of FIG. 5.

Referring now to the drawings, a slip sheet 10 is used in conjunction with fork lift trucks, whereas a load of boxes, barrels, bags, etc., is carried by a platen (a thin sheet of steel or the like) attached to the fork lift truck, which can slide underneath the slip sheet and its load by means of pulling the slip sheet by its extending tab 12 with a grabber bar which is fixed to an upright backstop that is moveable front to back of the platen area usually by means of hydraulics or electronics to relocate loads of all shapes and sizes.

One of the problems that may occur when the fork lift driver attempts to attach the grabber bar to the slip sheet tab is, that the tab may be resting flat on the floor or surface from which the load is to be pulled onto the platen, making the tab hard to secure. Also, problems may occur when loads are double stacked and the tab of the slip sheet has bent downward. Either of these conditions can result in the lift truck driver not being able to secure a firm hold on the tab of the slip sheet or grabbing the tab in a manner causing it to fold and wrinkle in the grip of the grabber bar. It is very important that the tab of the slip sheet rest evenly across the length of the grabber bar.

The unique functional feature that I have added to the plastic slip sheet are indented patterns designed to make the tab or tabs of the plastic slip sheet remain at a ready upward angle to achieve smooth effective fork lift handling and to reduce damage to the slip sheet.

Unlike a crease or shallow groove which will allow the extending tab to be manually positioned at an upward angle, the feature described herein and illustrated in the attached drawings (Fig's. 1-5) causes the tab of the slip sheet to angle upward automatically and remain at an upward angle when this or a similar pattern is indented into the surface of the finished plastic sheet. For^'- best results patterns should be used in conjunction with polyolefin resins with a tensil strength range of 3,000 PSI to 4,500 PSI and a vicat softening point of 260^βF. Finished sheet thickness range is 20 to 100 mils. The design comprises a pattern of alternating angled or otherwise shaped lines 14 indented into the plastic slip sheet surface between the load area 16 and the tab area 12 or areas. These indentations are pressed into the plastic slip sheet in a manner that causes the plastic to stretch downward (Fig. 3) wherever a line is placed. As the plastic is pulled downward the edge of the plastic sheet (or tab) automatically raises to a useful permanent upward angle (Fig. 2) .

The angle 0, length 1, shape, and depth d of the indented lines depends on the thickness of the plastic sheet, how wide the tab of the sheet is to be, and the amount of tab angle desired.

The indentations of the pattern are not quite connecting to one another (Fig. 1) , nor do they extend completely to the edge of the sheet itself. The reason for this is that when the plastic is pulled downward in the indented line areas these indented areas become weaker than the other areas of the sheet that are not indented. Leaving a small space between these lines adds to the strength of the slip sheet tab.

For shipping purposes, plastic slip sheets are usually stacked and banded in quantities of between 300 and 1,000 depending on sheet thickness. When sheets are stacked in this manner the tendency is for the sheet to lay completely flat because of the weight accumulation of the sheets themselves. When a single sheet is removed from the stack of sheets to be put into use, the tab area of a sheet with the patterned indentation will slowly raise into a ready position.

Even if the tabs of this sheet are pressed out of position between loads of material in box cars or truck trailers, the tab will return to a functional position when the stress of the neighboring load is removed.

Claims

C L A I M S

1. A slip sheet for pulling a load positioned thereon onto the fork arms of a lift truck, characterized by a thin sheet of deformable plastic material having at least one substantially straight edge, said sheet having a series of indentation formed therein, said indentations defining the boundary of a tab which is located inwardly adjacent to said edge, and said indentations being angled with respect to said edge, with the angle of each indentation being supplementary to the angle of each adjacent indentation.

2. Apparatus according to claim 1, characterized in that said indentations have first predetermined lengths and are separated from each other by second predetermined lengths, said first predetermined lengths being substantially larger than said second predetermined lengths.

3. Apparatus according to claim 1, characterized in that the angle between said indentations and said edge is a specific value which provides a desired amount of non- linearity between said sheet and said tab.

4. A method of forming a permanently bent tab in a margin of a sheet of plastic material, characterized by pressing a series of discrete indent tions into said sheet along a border between said tab and the remainder of said sheet, said indentations being angled with respect to the edge of said sheet.

5. A method according to claim 4, characterized by the further step of forming said indentations such that the angle of each indentation is supplementary to the angle of each adjacent indentation.

6. A device for supporting a load, characterized by a sheet of deformable plastic material having a flat main support portion, a flap portion connected to said flat main support portion by an elongated transverse hinge portion, said flap portion being outwardly inclined relative to said main support portion; and said hinge portion comprising a uniform continuous pattern of equal size and equally spaced indentations formed in said plastic material.

7. A device according to claim 6, characterized in that said indentations have triangular-shape flat unformed sheet portions therebetween.

8. A device .according to claim 7, characterized in that said indentations are elongated and adjacent ones of said indentations are oppositely equally inclined relative to the longitudinal axis of said hinge portion.

9. A device according to claim 8, characterized in that^' said indentations have equal lengths and said indentations have a first pair of closely laterally spaced end portions and a second pair of widely laterally spaced end portions.