Resilient Devices For Temporarily Binding And Gripping The Edge Of Materials

Abstract

A device for gripping the marginal edge of materials is provided which takes the form of an elongated continuous section of resilient material. The section has a pair of legs having gripping surfaces at one end thereof, and interconnected at the other end by a looped shaped web disposed between the legs. The legs, at their other ends, are mounted for pivotal movement. Upon separating movement of the legs at their gripping ends, the loop shape web flattens and a gripping force is generated as a reaction thereto. In certain embodiments, the device is shiftable to accommodate a multiplicity of thickness ranges of material.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to edge binding and gripping strips for the edges of material, and more particularly to devices for releasably securing stacked looseleaf sheets of material, such as paper, together at one marginal edge of the stack.

One of the most common types of temporary edge bindings for reports, sales literature, catalogs, etc. has been a resilient plastic strip which in cross section has a solid, essentially straight across end web from which a pair of legs project. The legs converge or angle inwardly coming into contact at their extreme ends. The resiliency of the material used in the legs and end web, as extruded, hold the ends of the legs together and when the legs are separated and the stacked sheets of paper inserted therebetween, this resiliency will cause the legs to tend to return to their original as extruded shape and to grip the inserted stack of papers, temporarily binding their edges.

While this type of edge binding in general works quite well, it does have certain undesirable aspects. One of these is that it has a fixed, non-adjustable profile thickness which results in unnecessary bulk when gripping just a few sheets; i.e., the device is formed to stationary profile thickness which is equal to the thickness required for gripping the maximum number of sheets and must retain that profile thickness even when less than the maximum number of sheets are inserted. This means that the gripped edge of the stack has a very wide, cumbersome profile with a minimum number of sheets.

SUMMARY OF THE INVENTION

According to the present invention, an edge binding strip for looseleaf sheets is provided which is formed with a minimal profile thickness, maintaining this minimal profile thickness when just a few sheets are gripped, and expanding to beyond its minimal profile thickness when necessary to accommodate greater thicknesses of stacked sheets. Also certain embodiments provide an edge binding strip that can be adjusted in profile thickness to accommodate different ranges of thickness of stacked sheets.

DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view showing an edge binding strip utilized to bind one edge of a stack of sheets of looseleaf material.

FIG. 2 is a sectional view taken substantially along the plane designated by the line 2--2 of FIG. 1, showing the cross section configuration of a conventional prior edge binding strip.

FIGS. 2a, 2b and 2c are sectional views taken substantially along the plane designated by the line 2--2 of FIG. 1, showing the cross-section configuration of one embodiment of an edge binding strip according to this invention, showing various states of expansion to accommodate different thicknesses of stacked sheets.

FIGS. 3a and 3b show the cross-section configuration of yet another embodiment of an edge binding strip according to this invention which can be expanded to accommodate various ranges of thicknesses of sheets of stacked material.

FIGS. 4a and 4b show the cross-section configuration of yet another embodiment of an edge binding strip according to this invention which can be expanded to accommodate various ranges of thicknesses of sheets of stacked material.

FIGS. 5a and 5b and 5c show the cross-sectional configuration of still a further embodiment of this invention which can be expanded from the normal position to two expanded positions.

FIGS. 6a and 6b show the cross-sectional configuration of still a further embodiment of an edge binding strip according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawing, FIG. 1 shows in perspective a stack of sheets of looseleaf paper temporarily bound together at one marginal edge of the stack by means of an edge binding strip. The strip depicted is not intended to represent any specific cross-sectional configuration, but rather depicts a manner in which strips of the prior art and the present invention are utilized. This figure forms a basis for illustrating the cross-sectional configurations of the prior art and the present invention.

Referring now to FIG. 2, the cross-sectional configuration of one conventional prior art binding strip is shown. (In this figure as well as the other sectional figures, cross hatching has been eliminated for clarity of illustration.) The strip is conventionally made of resilient plastic, having a pair of legs 10 joined at one end thereof by an essentially straight and continuous solid web section 12. In its normal or as-extruded condition, the legs 10 come together as shown in solid lines in FIG. 2.

In order to utilize the device, the legs 10 are spread sufficiently to accommodate the thickness of the stacked sheets, and the sheets are inserted therein. The legs are then released and will grip a stack of sheets due to the inherent resiliency of the legs, causing them to tend to return to the configuration as shown in FIG. 2. The thicker the stack of sheets the wider the legs must be spread until they reach a maximum position essentially as shown in dotted lines in FIG. 2, wherein the legs are substantially parallel with each other. If the legs are spread any further, they will not properly engage the stack of sheets so this parallel relationship is essentially the maximum open limit. In this maximum open condition, the width between the legs as they engage the paper is substantially the same as the width of the legs where they are joined by the web 12. This width or thickness being designated by the dimension a in FIG. 2.

It will be noted from an examination of FIG. 2 that even in its completely closed position, as shown in solid line, and without any sheets being gripped between the legs, the maximum profile thickness of the device is equal to the a dimension. Thus, even with very few sheets, the profile thickness of the strip is unchanged, in that it is determined by the fixed web 12 of this prior art configuration. The thickness never exceeds this a dimension since when the spread of the legs reaches this a dimension, the strip has reached its capacity.

This fixed maximum profile thickness, when gripping a very thin stack of sheets detracts from the desirability because of the inherent surplus of bulk, or thickness. This undesirable feature is substantially overcome by strips formed according to the present invention.

Referring now to FIGS. 2a, 2b and 2c, the cross sectional configuration of one embodiment of a binding strip according to this invention is shown. The binding strip is formed of a resilient plastic material such as styrene. (Of course, other resilient plastic or metal could be used.) The strip has a pair of legs 20 which have serrated gripping surfaces 22 at one end thereof. At the opposite ends of the legs 20 are a pair of abutting flat projections 24. The legs 20 are joined by looped shaped web 26 which web has a pair of straight arm portions 28 normally in contact or in close proximity with the legs 20 and an arcuate connection 30.

The device is shown in FIG. 2a in its completely closed or normally unused position without any sheets between the legs in which condition the gripping surfaces 22 are abutting. This is the configuration in which the strip is normally formed or the as-extruded shape. FIG. 2b depicts the strip engaging a stack of sheets of minimal thickness, FIG. 2c depicts the strip engaging essentially the maximum thickness of stacked sheets.

As can best be seen in FIG. 2a, the maximum profile thickness is across the strip where the legs are joined to the web and designated by the dimension b. The legs gradually converge or angle inwardly from this maximum width to their other extreme ends which are in contact with each other. The inherent resiliency of the plastic maintains the strip in this as-formed shape shown in FIG. 2a with the gripping surfaces 22 in contact with each other and the abutting projections 24 also in contact with each other. It will be noted that the dimension b is substantially less than the dimension a. (FIGS. 2 and 2a, 2b and 2c are drawn to essentially the same scale.) In fact, the dimension a can be as much as 30 percent greater than the dimension b for devices of the same maximum capacity as will become apparent presently.

Referring now to FIG. 2b, when just a few sheets are gripped between the legs 20, the legs flex resiliently to grip the sheets in a manner similar to the device of the prior art, and there is no appreciable increase in the profile thickness of the binding strip. However, as more and more sheets are added, a different type of action takes place. This type of action is characterized by the legs 20 pivoting against each other at the ends of their abutting projections 24 as shown in FIG. 2c, with a corresponding flattening and rearward deformation of the curved portion 30 and the straight portions 28 of the web 26. This results in a gripping action by the legs generated, at least, in part as a function of the resiliency and deformation of the web tending to pull the legs together as a reaction to the separating of the legs. This allows the legs 20 to expand to a thickness wider than the b dimension and in fact expand as much as 30 percent beyond this dimension to the dimension c which is substantially equal to the a dimension shown in FIG. 2. At this point, the legs have reached their maximum open capacity beyond which they will not effectively engage the stacked material. However, it is not until an appreciable thickness of stacked sheets have been gripped between the legs, that the legs in fact start expanding past the b dimension, and they do not actually reach the maximum c thickness until the maximum number of sheets are gripped therebetween. Thus, an edge binding strip is provided which has a much thinner profile thickness when just a few sheets are secured and yet can expand beyond this minimum to accommodate a greater number of sheets while maintaining the thinnest possible profile for the given thickness of sheets being secured.

Referring now to FIGS. 3a and 3b, another embodiment of an edge binding strip according to this invention is shown. This embodiment is actually adjustable or shiftable to accommodate two different ranges of thickness of stacked sheets. FIG. 3a shows the cross sectional configuration of the strip in its as-formed condition suitable for use with the thinner range of thickness and FIG. 3b shows the device shifted to its position for accommodating the thicker range.

In this embodiment, a pair of legs 32 are provided which have gripping surfaces 31 at one end thereof similar to the gripping surfaces 22 of the previous embodiment. The legs 32 terminate at their opposite ends in projections having abutting points 33 defined by rearwardly directed sloped surfaces 34 and forwardly directed sloped surfaces 35. A web member 44 similar in size and configuration to the web 26 of the previously described embodiment joins the legs 32 at their ends opposite from the gripping surfaces 33. A pointed wedge member 36 is carried by a second web member 38 interconnecting the legs 32 and located outside the confines of the legs. The wedge 36 has a pair of forwardly directed cam surfaces 40 and a pair of rearwardly directed cam surfaces 42 which together define laterally directed points.

In the thinner, as-extruded configuration as shown in FIG. 3a, the abutting points 33 of the legs 32 also rest against the cam surfaces 40 of the wedge 36 and the gripping edges 31 of the legs 32 are in contact with each other. When the legs are separated to accommodate a relatively thin stack of sheets, the inherent resiliency of the legs provides the gripping action as in the previously described embodiment as shown in FIG. 2b. As the legs are further separated, the legs will pivot against the abutting points 33 allowing the legs to continue to open and causing a flattening of the web 44 in much the same manner as of the previous embodiment, and grip until a maximum has been reached, this maximum being substantially thicker than the device in its closed position shown in FIG. 3a.

If it is desired to accommodate a thicker range of stacked sheets, the device is shifted to the position shown in FIG. 3b. This is done by pushing the wedge 36 toward the web 44 which will cause the cam surfaces 40 to separate the sloping surfaces 34, this movement continuing until the points on the wedge 36 have passed the points on the legs 32 and the forward surfaces 35 on the legs engage the rear cam surfaces 42 on the wedge. This portion is shown in FIG. 3b with dimension d being the new profile thickness which can now accommodate approximately 100 percent greater thickness of sheets than b. As this thickness of sheets increases, the further spreading of the legs will be accomplished by the end surfaces 35 of the legs pivoting against the cam surfaces 42 with a corresponding flattening of the loop web 44 which will allow the legs to spread open still further to the overall profile thickness e shown in FIG. 3b. Thus, with the device shown in FIGS. 3a and 3b, two separate thickness ranges of stacked sheets can be provided for in a single device, thus eliminating the necessity of carrying two different size strips in stock.

FIGS. 4a and 4b show the cross section configuration of another embodiment of an edge binding strip which also is shiftable to two positions for accommodating two different size ranges of stacked sheets. In this configuration, a pair of legs 46 is provided which have gripping surfaces 47 similar to those in the previously described embodiments. The legs 46 also have abutting surfaces 48 at the opposite ends thereof each of which surfaces 48 has provided therein a notch 50. A loop shaped web 52 is disposed between the legs 46 and interconnects the legs. A wedge 54 is carried by the loop 52 and extends toward the abutting surfaces 48. The wedge 54 has a pair of points 56 on opposite sides thereof. In the narrower configuration as shown in FIG. 4a, the gripping edges 47 are in contact with each other as are the abutting surfaces 48. In this configuration, the device operates substantially as described with respect to FIGS. 2a, 2b and 2c. This constitutes the position for receiving the narrow thickness range of stacked sheets.

When a wider thickness range is desired, the loop web 52 is pushed toward the abutting surfaces 48 which will cause the wedge 54 to separate surfaces 48 until the points 56 of the wedge engage the notches 50. This then constitutes the position for receiving the thicker range of stacked sheets as shown in FIG. 4b. The gripping edges 47 are separated as shown therein which constitutes the thinnest stack of sheets which can be accommodated and the legs open from there to the maximum. Thus, this embodiment, as the previous embodiment, can accept a wide range of thickness of stacked sheets.

The embodiment shown in FIGS. 5a, 5b and 5c is quite similar to that shown in FIGS. 4a and 4b except that it can be shifted to three different thickness range accepting positions. In this embodiment, the legs 60 are provided with spaced rear surfaces 62. These surfaces 62 have teeth-like projections 64 extending therefrom and as shown in FIG. 5a are normally in contact. A wedge 66 is provided carried by a loop shaped web 67. The wedge 66 is barbed in shape having a central notch 68 and an end notch 70. In the position shown in FIG. 5a, the device is positioned to receive the thinnest range of stacked sheets. By moving the wedge 66 in a position as shown in FIG. 5b, the device is set to accommodate an intermediate thickness range of sheets and by moving the device to the position shown in FIG. 5c, the maximum thickness range of sheets is provided for. This device operates in a manner very similar to that shown in FIGS. 4a and 4b.

Referring now to FIGS. 6a and 6b, still another embodiment of a device of this present invention is shown. This device is quite similar to that shown in FIGS. 2a, 2b and 2c except that the legs and web are somewhat differently shaped. In this embodiment, a pair of legs 72 are provided, having flat end surfaces 74 connected by a loop shaped web 76. In this embodiment the legs 72 diverge outwardly from the end surfaces 74 to a central portion 78 and then converge inwardly to the gripping ends 80. Also, the web 76 is somewhat different in shape from the web shown in FIGS. 2a, 2b and 2c. However, this device works quite similarly to that depicted in FIGS. 2a, 2b and 2c; i.e., initially for a thin stack of sheets, the resiliency of the legs will provide the gripping action and as the thickness of the stacked sheets increases, there will be a pivoting action about the abutting surface with a flattening of the web to provide at least in part the gripping action.

While several embodiments of the invention have been shown and described, with certain modifications it is understood that other modifications may also be made. For example, the loop shaped web may take on many different configurations; indeed the term loop as used herein includes any non-linear interconnection which can change shape responsive to movement of the legs such as an arcuate shape, a tent shape, etc.

Claims

What is claimed is:

1. A device for securing, binding, or gripping sheet materials at a marginal edge of said materials, comprising a continuous section of resilient material having a pair of legs and connecting means joining said legs at one end portion of said legs, said legs extending from said connecting means and terminating in cooperating material engaging end portions adapted to clampingly secure the materials therebetween, said connecting means including a loop-shaped web member interconnecting said legs and disposed therebetween, said device being formed with surface means at the end thereof remote from the material engaging end portions of the legs including a pair of opposed separable surfaces at the ends of the legs, said surface means being normally in mutual engagement and disposed to provide pivotal movement of each of the legs, and to generate a gripping force between said legs in reaction to separating movement of said legs at their material-gripping end portions, said loop-shaped web member being disposed between said surfaces and said material engaging end portions of said legs.

2. The invention as defined in claim 1 wherein said legs are in engagement with each other at their end portions remote from said gripping end portions and pivotal against each other.

3. The invention as defined in claim 1 wherein the outer surface of said legs become progressively closer together from the remote end to the gripping end portions.

4. The invention as defined in claim 1 wherein the looped shape web has a pair of generally straight arms each in contact with one leg and an arcuate portion interconnecting said arms.

5. The invention as defined in claim 1 wherein each leg diverges outwardly from the remote end portion to an intermediate portion and thence inwardly.

6. The invention as defined in claim 1 further characterized by shifting means to selectively move and retain the normally engaging surfaces outwardly from each other whereby to expand the capacity of said device.

7. The invention as defined in claim 6 wherein said shifting means includes a wedge member disposed to selectively separate the remote-end portions of said legs and provide a fulcrum for pivoting.

8. The invention as defined in claim 7 wherein said wedge member is carried by the loop-shaped web within the loop.

9. The invention as defined in claim 7 wherein said wedge member is carried by a second web member external of the legs.

10. The invention as defined in claim 6 wherein said shifting means includes means to shift and retain the pivot point to a plurality of discrete positions outwardly from the normal position.