US3057357A

US3057357A - Rigid-prong self-opening binder

Info

Publication number: US3057357A
Application number: US753548A
Authority: US
Inventors: James K Duncan
Original assignee: Duncan Research
Current assignee: Duncan Research
Priority date: 1958-08-06
Filing date: 1958-08-06
Publication date: 1962-10-09
Anticipated expiration: 1979-10-09

Description

J. K. DUNCAN RIGID-PRONG SELF-OPENING BINDER Oct. 9, 1962 Filed Aug. e. 195s 2 Sheets-Sheet 1 fZZ @X24 @E4 ZZ" Emmi;

frzec/ 90.729615 racer? 2 Sheets-Sheet 2 Filed Aug. 6, 1958 3,057,357 RIGlD-PRQNG SELF-@PENING BNDER `'lames K. Duncan, Chicago, Ill., assigner to Duncan Research, Chicago, Ill., a partnership Filed Aug. 6, 1958, Ser. No. 753,548 7 Claims. (Cl. 129-24) My invention relates to an improved rigid-prong selfopening binder.

In notebooks, brochures, and loose leaf books it is necessary to bind from a few sheets of paper to a stack of papers perhaps 1" thick to form a unitary pamphlet or book. Preferably, the binding should be such as to permit the respective sheets to be laid at in opened position to permit the user to read the same without holding the sheets back. Plastic binders with large numbers of relatively flexible iingers have been used for this purpose. These, however, require the use of special machines to flex the many fingers to open position in unison and to permit the insertion of the sheets. Removal or change of the sheets can also be accomplished only with access to such special machines. Spiral wire binders are likewise generally useful for pamphlets of this general type, but they too require special machinery to thread the spiral wire thro-ugh the openings in the sheets to form the completed pamphlet.

In accordance with the present invention an improved binder mechanism is provided in which the sheets may be inserted and removed without the use of special machinery. At the same time, however, the pamphlet, when formed, is a unitary object in which the sheets are held in assembled relation and do not tend to pull free. In brief, the apparatus of the present invention is characterized by the use of prongs which are relatively rigid and are not flexed to add or remove the sheets. The prongs may be made relatively heavy to provide a booklet with only a small number of holes in each page including, for example, conventional three and five hole pages. The prongs are carried by, and are preferably formed in a unitary structure with, a pair of spaced complementary relatively movable elongated rockable members. These members are permanently connected together by an intermediate or fulcrum member in the form of a flexible membrane or hinge serving to hold them from spreading while permitting them to assume either a position holding the prongs in closed position or a position holding the prongs in opened position. Further in accordance with the present invention a movable spreader is located at the edges of the rockable members opposite the fulcrum member and prongs. This spreader in one position holds the rockable members in the prong-opening position for the insertion, removal, or replacement of the sheets.

In accordance with one embodiment of the present invention, the fulcrum member is in the form of a ilexible diaphragm which is formed from a unitary plastic extrusion with the rockable members. Outboard this diaphragm member (on the side opposite the prongs) there is provided a spreader member that is slideably positioned in the unit. This spreader member is a relatively rigid plastic extrusion having outboard and inboard surfaces that slide respectively inside and outside the edges of the rockable members. With the prongs in the closed position, the outboard sliding surfaces of the spreader member bear on the inside faces of the rockable members to tension the web and provide lever action urging the prongs to closed position. When the prongs are to be opened, the spreader member is withdrawn and reinserted in alternate position Where the inboard surfaces bear on the outside edges of the rocking members. It then holds together the edges of the rockable members opposite the prongs. At this time, the diaphragm is exed to an Patented Oct. 9, 1962 ICC arcuate conguration and the prongs are swung to opened position where the papers may be inserted or removed. The operation of moving the spreader from the prongclosing to the prong-opening position is merely one of slidably withdrawing the same from the prong-closing position (outboard surfaces bearing against the rockable members) and sliding it back on in the prong-opening position (inboard surfaces bearing against the rockable members).

It is therefore a general object of the present invention to provide an improved self-opening binder using relatively rigid prongs.

Another object of the present invention is to provide an improved self-opening binder using relatively rigid prongs that is particularly adapted to manufacture fromy plastic materials in an inexpensive form suitable for use by students, small business, and in other applications where the complexity and expense of special opening and closing equipment cannot be tolerated.

Still another object of the present invention is to provide an improved binder mechanism that is especially adapted for manufacture by the use of plastic extrusion technique.

Yet another object of the present invention is to provide an improved binder in which all parts, including relatively rigid prongs, can be made from an extrusion.

Yet another object of the present invention is to provide an improved binder mechanism in which a pair of relatively rigid prong-holding rocking members are connected together by a movable web serving as a fulcrurn and in which a spreader member serves in one position to tension' the web and force the prongs to closed position and in another position serves to iiex the web and open the prongs.

It is still another object of the present invention to provide a untiary binding having a shiftable member which in one position forces the prongs to open position and holds them in that position and in another position forces the prongs to closed position and holds them in that position.-

Further it is an'object of the present invention to provide a binding having the foregoing objects and advantages and in which the sheets may be laid flat in the opened position for use.

Further it is an object of the present invention to provide a binding having the foregoing objects and advan-l tages Which has an essentially flat back side to permit the binding to be laid on its back with the prongs either in open or closed position to permit the sheets to be readily inserted and removed with the back in such position and to permit the assembled brochure, pamphlet or book to be read with the pages laid flat.

Yet another object of the present invention is to provide an improved rigid prong self-opening binder which includes conformations serving as stops to prevent undue flexure or bend.

Another object of the present invention is to provide a binder which can be readily manufactured by plastic extrusion technique in conjunction with cam elements operative on the soft heated plastic to form the cooperating' prong portions.

Yet another object of the present invention is to provide an improved rigid-prongbinder with readily removable prongs to accommodate paper having varying numbers of holes.

Still another object of the present invention is to provide an improved rigid-prong binder using prong conformations that provide a high degree of strength while at the same time aiding the insertion of sheets.

Still another object of the present invention is to provide an improved self-contained binder that is characterized by resistance to breakage, resistance to changes in temperature and moisture, adapted for use with plastic materials having natural and attractive single or multiple colors, is suitable for use in many sizes adapted for varying numbers of pages and varying page dimensions, provides a back portion having a convenient place for labels, is suitable for use with a small number of fingers and hence only a small number of holes in the sheets of paper or in the alternative can be used with a large number of fingers and a corresponding large number of holes in the sheets, and incorporates other features of construction combination and arrangement rendering the binder especially suitable for practical low-cost application where special binding machinery cannot be used.

The novel feautres which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, together with further objects and advantages thereof, Will best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIGURE l is a top plan view of a completed booklet bound with a binder mechanism constructed in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary end elevational view of the booklet of FIGURE 1;

FIGURE 3 is a greatly enlarged cross-sectional view through the axis 3 3, FIGURE l;

FIGURE 4 is a view like FIGURE 3 but showing the binder in the opened position for the reception or removal of papers;

FIGURE 5 is a view like FIGURE 3 but of a modied form of the binder;

FIGURE 6 is an enlarged fragmentary view of FIG- URE 5;

FIGURE 7 is a View like FIGURE 5 but showing the binder in the opened position for the reception or removal of papers;

FIGURES 8 and 9 are views like FIGURES 3 and 4, respectively, but showing a further alternative embodiment of the present invention;

FIGURES l0 and ll are Views like FIGURE 3 but showing modification of the binders of FIGURES 3 and 8, respectively, suitable for manufacture from sheet metal; and

FIGURE l2 is a cross-sectional view through axis 12-12, FIGURE 11.

Referring now to FIGURE 1, the completed booklet there shown consists of a binder portion shown generally at 20 and a booklet portion indicated generally at 22. The latter consists of a stack of sheets of paper or the like 22a, FIGURE 2, which are sandwiched between a pair of backing or cover sheets 22b, FIGURE 2. As hereafter described in detail, the binder shown generally at 20', FIG- URES l and 2, defines a series of relatively rigid prongs 24 which pass through the registered holes 22e in the sheets and covers of the booklet portion to hold the same together and define a booklet.

The structure of the binder portion 20 is best seen in FIGURE 3. It consists of a pair of opposed complementary relatively rigid

rockable members

26 and 28. A fulcrum member in the form of diaphragm 30` is formed integrally with and extends between these opposed rocking members as shown. Each prong 24 is likewise formed integrally with the rockable members and extends from the rockable member 26 to the rockable member 28, as shown. The prongs are severed or interrupted at 24a to form the cooperating short prong element or portion 24b and the long prong element or portion 24e.

The spreader in the form of slide 32 is received on the inboard faces of the

rockable members

26 and 28 to close the prongs, as in FIGURE 3. In the alternative this member fits over the outboard faces of these members to open the prongs as in FIGURE 4. The spreader 32 has a backbone 32a which is relatively rigid and a pair of opposed ange portions 32b and 32C, respectively. As shown, the

outboard edges of the flanges 32b and 32C each have a longitudinal V-shaped groove or way, 132b and 132C, respectively. These ways received the similarly shaped inboard V-shaped longitudinal ridges on the inboard faces of the

rockable members

26 and 28, respectively, these ridges being indicated at 26a and 28a, FIGURES 3 and 4. On their inboard edges, the anges 32b and 32C each have a longitudinal ridge 23212` and 232C, respectively. These mate with and ride in the longitudinal V-shaped grooves or ways, 26b and 28h, respectively, formed on the

rockable members

26 and 28 as shown in FIGURE 4.

On its back or out-board side the backbone portion of the spreader 32 has a pair of spaced overhanging portions 32d joined by a recessed portion to define the shallow groove 32e. A removable title card 34, which may be of paper or any other suitable material, is slidably disposed within this groove and serves to bear the titleI of the booklet or other information as desired.

Preferably, a pair of caps 36 are located at the opposite ends of the binder 20. Each of 4these may be of any construction well known to the art. In the form shown, they are formed of stamped sheet metal and have overhanging ears 36a, FIGURES 1 and 3, which frictionally grip the ends of the outboard faces of the

rockable members

26 and 28 to provide an attractive end covering for the binder which may be readily removed to permit opening of the binder.

As shown in FIGURE 3, the binder 20 is in the closed position. In this condition, the flanges 32b and 32C of the spreader 32 bear outwardly against the inside or inboard faces of the

rockable members

26 and 28, respectively. The spreader 32 is held in this position by the ways 132b and 132e which receive the ridges 26a and 28a of the rocking

members

26 and 28, respectively. This outward force is suflicient to bring the portions 24b and 24e -of the prongs 24 into engagement and to pull the diaphragm portion 30 into a taut position. It will be noted that this action is in the nature lof lever action with the taut diaphragm portion 30 serving as a fulcrum to prevent spread of the rockable members and with the ends of the

rockable members

26 and 28 spaced in accordance with the dimensions of the spreader 32, and with the ends of the prong portions 24b and 24C brought together in scissors action as shown.

The binder 20 is changed from the cl-osed position to the `open position by sliding the spreader 32 out of the binder, pinching the free ends of

rockable members

26 and 28 together (by grasping them adjacent the grooves 26b and 28b), and then reinserting the spreader 32 as shown in FIGURE 4. At this time the inboard ridges 232b land 232e 'of the spreader are received in the grooves 26b and 28b and the binder is held in the position of FIGURE 4. At this time the spreader acts as a clamp. The

rockable members

26 and 28 rock in relation to each other in direction to spread or open the relatively rigid prong portions 24b and 24C as is shown in FIGURE 4. The fulcrum member '30 is flexed in this action and in offering resistance to the squeeze applied to Ithe rockable members fit serves in lever action to rock the rockable members as shown and to open or spread the rigid prongs.

The lever act-ion of the spreader in the opened condition of FIGURE 4 differs from that in the closed condition of FIGURE 3 in that the diaphragm portion 30 is under compression rather than tension, in that the ends of the

rockable members

26 and 28 are held together rather than spread apart, and in that the prongs 24b and 24C are not in engagement and exent no forces in the mechanical system.

As shown in FIGURES 1-4, the backing is made of plastic material. Any suitable plastic may be employed. The fulcrum member 30 in the form of a diaphragm or web is made relatively thin and flexible. The spreader 32, the

rockable members

26 and 28, and the prongs 24 are made relatively thick and inflexible. Vinyl plastics polystyrene, butyrate, and polyethylene plastics are conapaiser sidered especially suitable for the backing shown in these iigures because these materials in relatively thin sections display a high degree of flexibility and in fairly thick sections display suicient rigidity for the purposes of the binder.

Preferably, the binder is made from plastic extrusions. In the case of slide 32, such construction involves no problems, since the cross-section along the length of this member is uniform. In the case :of the

rockable members

26 and 28, diaphragm 30, and prongs 24, it is contemplated by the present invention that extruded parts be initially made with the prongs 24a in the form of a continuous section having the cross-section of the prongs slightly opened. The soft plastic of this section is turned in by passing the extrusion over suitable xed cam elements, thus closing the prongs. After formation of this extrusion, the portions between the prongs 24 are removed by sawing or milling operations to form the unit as seen in FIG- URES 1-3.

In FIGURE l0, the binder of FIGURES 1-4 is shown in a modiiied form suitable for manufacture from sheet metal. Parts similar to those in the binder of FIGURES 1-4 in this figure are indicated by like reference numerals with the number 400 added. In the construction of FIG- URE 10, the relatively rigid

rockable members

426 and 428 are defined by mating double thicknesses of the sheet metal of which the binder is made. The relatively flexible diaphragm or web part 430 is defined by a single thickness of the same sheet of metal. The prongs 424 are likewise formed of a single thickness of this metal, with the interruption 424a serving to define the two prong parts. In the unit of FIGURE 10, the spreader 432 is similarly formed of sheet metal with iiange parts 432b and 432e, as shown. The title card 434 is received within the shallow slot yor groove defined by the spreader 432, as shown.

In the prong closed position of FIGURE 10, the outboard faces of the flanges 432b and 432C of the spreader bar 432 bear against the inboard faces of the free ends of the

rockable members

426 and 428, as shown. This tensions the diaphragm part 430 and tends to flex it in the pnong-closing direction in the same lever actio-n as is above described with reference to FIGURE 3. The prongs are thus held closed.

To open the prongs, the spreader 432 is removed, the free ends of the

rockable members

426 and 428 are pinched together, and the spreader 432 reinserted with its inside faces of the iianges 432b and 432e bearing against the outside faces of the

rockable members

426 and 428. This holds the rockable members in the prong- Opening position similar to that of FIGURE 4 and permits the insertion or removal `of the sheets constituting the booklet.

FIGURES 5-7 show another alternative form of the binder of FIGURES 1-4. In this form, the parts similar to those of FIGURES 1-4 are indicated by like reference numerals with 500 added. As shown, the rockable members 526 and 52S are for-med of a relatively thick section and define a pair of opposed grooves 526C and 528C. The spreader 532 fits in these grooves and in the inserted position of FIGURE 5 tends to spread the adjacent portions of the

rockable members

526 and 528. This rocks the prong 524 in the closing direction against the diaphragm 530 serving as a fulcrum. This serves to hold the prong in closed position.

The binder of FIGURES 5-7 is Shown in opened position at FIGURE 7. The binder is thus opened by pinching the free ends of the rockable members 526 `and 528 together, thereby flexing the diaphragm portion 530 and rocking the

rockable members

526 and 528 in the prongopening direction.

The prongs of the binder of FIGURES 5 to 7 are interrupted only at the portion adjacent the top rockable member 526. These prongs are made of progressively decreasing cross-sectional area extending from their root ends 524C, FIGURE 5, to their tip ends 524d, FIGURE 5. This `serves to provide maximum hook strength in the prongs for the `amount of material employed and in addition serves to facilitate the insertion and removal of the sheets by providing a relatively small prong area at the point where the sheets must be laid over the prongs.

The binder of FIGURES 5 to 7 has a pair of relatively rigid heaving heavy covers which are indicated at 540 and 542, respectively. These have flexible root portions at 540a and 542a, respectively, which freely ex as shown in FIGURE 7 to open the covers for use of the booklet and for the insertion or removal of the sheets. The

covers

540 and 542 are secured in the

rockable members

526 and 528 by inserting their ends in the slots 526d and 528ml, as shown. Adhesive 541, FIGURE 6 is used for this purpose.

The binder of FIGURES 5 to 7 is closed and opened through the insertion and removal of the spreader 532.

This is channel shaped to hold a label strip. This effects the same lever action as is shown in FIGURE 3 with respect to the closed condition of the binder. With respect to the opened position, the binder of FIGURES 5 to 7 is held by pinching the rockable members with the fingers. If desired, additional clips or locks (shown in dotted line form at S44 of FIGURE 7) may be used to hold the rockable members in the prong opening position. The spreader 532 is composed of a transparent plastic channel part 532:1 with its ends overlaying the label strip 532b, as shown.

FIGURES 8 and 9 show still another modication of the construction of FIGURE 3. Parts corresponding to those of FIGURE 3 are given like reference numerals with 600 added. In this form, the member 630 which joins the

rockable members

626 and 628 is -in two-part form, one pant being the headed part 630a which is formed with a cylindrical head along its length as shown. The other part, 63017, is a cooperating socket part which is received over the head part 63051 and forms a rocking joint. In the closed condition of the prongs 624, shown in FIGURE 8, the flexed spring spreader 632 urges the

rockable members

626 and 628 in prong-closing direction and rocks the par-ts of the prong 624 closed with the member 630 serving as a fulcrum in the same lever action as is above described with reference to FIGURE 3. To open the prongs 624, the spreader 632 is withdrawn as above described and the free ends of the rockable members 626 land 628 are pinched together to swing the joint of connecting member 630 as shown in FIGURE 9, thereby opening the prongs 624 for the insertion or removal of the sheets.

In the construction of FIGURE 8, the prong portions 624e and 624b are formed at their ends in concave and convex nesting sections as shown. These serve to key the prong parts together, when closed, to secure the pages more eifectively. The nesting portions are constant section along the length of the unit, and `hence can be extended as hereafter described.

FIGURE 11 is a View like FIGURE 8 showing a binder similar to that of FIGURE 8 but for manufacture from `sheet metal. Parts corresponding to those in the unit of FIGURE 8 are indicated by like reference numerals with 1000 added. In the unit of FIGURE 11, the top rockable member 1626 is formed integrally with the top portion of the member 1630, as well as with the top part 1624a of the prong 1624. The top portion of member 1630 is bent to dene a cylindrical surface at 163011 to form the inner member of the ball joint. Similarly, the bottom rockable member is formed integrally with the bottom portion 1630b of the member 1630, and with the bottom portion 1624b of the prong 1624. A socket to receive the cylindrical conformation 1630a of the member 1630 is formed by alternate clock'wise and counterclockwise mating curved

portions

16300 and 1630d of the portion 1630b. This construction is shown in side elevational view in FIGURE 12.

All of the foregoing binder constructions are characterized by the use of relatively rigid prongs which are not flexed for the removal of the sheets. This serves to simplify the construction and in addition serves to hold the sheets in place in firm and unyielding fashion. Moreover, in all of the binder constructions here shown, a pair of relatively rigid rockable members are used. These serve to provide a rm backing construction that protects the sheets bound. In addition, they coact with the spreader used in the respective constructions to form a rigid backbone or back part which serves to carry an appropriate label or title and in addition contributes to the provision of a firm and rigid structure. This back part is also adapted to lay flat in the position of FIGURE 2 to rest on a table or other surface with the pages spread out for convenient reading or other use without the necessity of holding any of the pages down.

It will be further observed that all of the constructions here shown utilize yan

intermediate fulcrum member

30, 430, 530, 630, etc., which is tensioned tin the closed position of the binder. This member in every form shown permits rock-able of the rocking members in relation to` each other, so that the spreader-by spreading the free ends of the rockable members-tilts the rockable members about the fulcrum member to urge the prongs to closed position. Thus the roclcable members and the slide member coact with the fulcrum member to form -a positively closed binder with the spreader in place. With the spreader removed, this restraint and the laccompanying lever action does not take place and the rockable members are free to tilt to the prong-opening position. Sheets can then be readily removed or inserted and the spreader replaced to restore the initially complete and rigid construction.

The forms of the invention shown in FIGURES 1 4, 5 7, and 8-9 have the advantage of being suitable for construction from plastic materials, especially styrene vinyl, butyrate and polyethylene plastics. Moreover, as above specifically discussed wlith respect to the form of FIGURES 1 4, the conformations are such las to lend themselves to construction by plastic extrusion techniques. This is highly desirable as it permits relatively inexpensive manufacture with a very limited amount of machining. In addition, it is possible to form a binder like those of FIGURES 1-4 and 5-7 by extrusion of these shapes with the prong-forming portions in the form of a partially or wholly spread out continuous section followed by movement of the soft extrusion Ialong fixed cam elements serving to bend the soft prong-forming portion to the final desired closed prong shapes. last technique is particularly suitable for manufacture of units with nesting prongs suoh as are shown in FIG- URE 8.

In FIGURES 3, 4, 5, `and 7, the fulcrum members and 530 are shown in various positions of flexure and lack of flexure. The actual conformations assumed by these members under specific conditions depend upon the specific material use for thern, their dimensions (especially thickness), and the extent of the tension and compression lapplied to them. It will be understood that the specific conforrnlations shown `are illustrative only land the respective fulcrum members will serve their purpose successfully if they are capable of withstanding the tension created by the action of the slide or spreader member, and are sufficiently flexible to permit the rockable members to rock -in relation to each other at all positions of roclcable member movement. Moreover, if desired, the fulcrum members may be made more flexible by punching or otherwise placing holes in them, such holes serving to increase the flexibility of these members to the desired extent, or they may be made of more flexible material than the remainder of the binding.

While the rocleable members and the prongs are here described as relatively rigid this term is of necessity used in a relative sense. A considerable degree of flexibility This may be provided in these parts without impatiring the operation of the binder. The yimportant point is that these parts do not flex under normal binder use and may accordingly be made as rigid yas desired without prejudice to the ease of insertion and removal of the sheets.

The rockable members described above rock relative to each other yand form a complementary pair. It will be understood that it is this rocking movement of the members in relation to each other and not the 'absolute movement of either alone that is necessary tand `is referred to in the claims.

If desired, the spreaders, such as spreader 632, FIG- URE 8, may be of transparent plastic of convex shape with la label on the inside face of the same. The spreader then serves to enlarge the lettering on the label.

The term hook moment is used herein to designate the prong-closing moment imparted to the rigid prongs, which is analogous to the moment on a lifting hook. It will be noted that the spreader urges the rockable members apart and acts against the thin flexible membrane or other member that holds the rookable members against spreading intermedi-ate their edges. Each rockable member is thus subjected to a force couple tending to rook the same in prong-closing direction and is resisted by the force exerted by the prongs. As in a hook, this force gives nise to a varying bending moment in the prongs.

While I have shown and described specific embodiments of the present invention, it will of course be understood that numerous modifications and alternative constructions may be employed without departing from the true spirit and scope thereof. In particular, other forms of relatively rigid rockable members may be provided with any appropriate number of suitable relatively rigid prongs, joined by other forms of fulcrum members, and provided with other suitable spreading elements at their free ends to define the binder. It will, of course, be understood that the lappended claims are intended to cover lall such modifications and alternative constructions as fall within their spirit and scope.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A two-part unit for sheets having perforations adjacent one edge, the unit compnising a rst part in the form of an elongated member defining a pair of elongated complementary rockable members each having spaced longitudinal edges, a thin flexible membrane joining said members intermediate the edges, respectively, and rigid mating prongs extending in pairs from one edge o-f one rockable member and from the corresponding edge of the other rockable member, said prongs being adapted to pass through the perforations of the sheets; and a second part in the form of a slide member having overhanging faces and adapted alternately to slide between or to slide over said rockable members adjacent the other edges thereof, the slide serving when between the rockable members to spread the rookable members, tension the membrane, and close the prongs, and when over the rockable members to draw the rockable members together at their edges opposite the prongs, collapse the membrane, and open the prongs.

2. A two-part blinding unit for sheets having perforations adjacent one edge and suitable for manufacture by extrusion processes, the unit comprising a first part in the form of an elongated member defining a pair of elongated complementary rockable members each having spaced longitudinal edges, a thin flexible membnane joining said members intermediate the edges, respectively, `and rigid interrupted prongs extending betwee-n one edge of one rockable member and the corresponding 'edge of the other rockable member, said prongs being 'adapted to pass through the perforations of the sheets, said rst part being of uniform cross sectional conformation throughout its length with the exception of the prongs and the prongs being of uniform cross sectional conformation, whereby the first part may be made by extrusion methods and the prongs formed by cutting operations; and a second part in the form of a slide member of uniform cross section throughout its length, having overhanging faces, and adapted alternatively to slide between or to slide over said rockable members `adjacent the other edges thereof, the slide serving when between the rockable members to spread the rockable members at their edges opposite the prongs, tension the membrane, and close the prongs, and when over the rockable members to draw the same edges of the rockable members together, ex the membrane, and open the prongs.

3. A binding unit suitable for manufacture by a plastic extrusion process and suitable for holding a plurality of sheets having perforations adjacent one edge, said unit comprising a lpair of elongated relatively thick and rigid complementary plastic rockable members each having spaced longitudinal edges; rigid plastic prongs on at least one rockable member extending between one edge of one member and the corresponding edge of the other member to form rings to hold said sheets by passing through said perforations, said members having complementary ways adjacent the opposite edges thereof; a relatively thin fiexible plastic membrane joining said members intermediate the edges of said members, said membrane being sufiiciently iiexible to normally permit said rings to open; said members, said rings and said membrane being formed of a continuous plastic extrusion cut to form the unit and rings whereby said members, said rings and said membrane are unitary; and a spreader receivable in said ways when said rings are closed by urging said other members apart to tension said membrane and hold said members in the position at which said rings are closed.

4. A binding unit for sheets having perforations adjacent one edge, the unit comprising: a pair of elongated complementary rigid rockable members each having spaced longitudinal edges; rigid prongs on at least one rockable member extending between one edge of one rockable member and the corresponding edge of the other rockable member, said prongs being adapted to pass through the perforations of the sheets and in closed position defining a hook that resists closing movement of said one edge; means joining said members intermediate their respective edges, said means permitting relatively free rocking movement of the members to move the prongs from prong closed to prong opened position and holding said members intermediate their edges from spacing movement; and a slidable spreading located between said last means and the other edges of the rockable members, respectively, said last means in one position bearing in column action against the rockable members to spread the same in prong-closing movement, tension said means, and close the prongs; said spreader also having parts to engage the rockable members in the prong opened position to hold the same against prong-closing movement.

5. A binding unit for sheets having perforations at one edge, the unit comprising: a pair of elongated complementary rigid rockable members each having spaced longitudinal edges; means defining rigid interrupted prongs on at least one rockable member extending between one edge of one rockable member and the corresponding edge of the other rockable member, said prongs being adapted to pass through the perforations of the sheets; and in closed position defining a hook that resists closing movement of said one edge; a flexible membrane joining the members intermediate their edges; a spreader adapted to t between the rocking members near the other edges thereof to bear against the inside faces thereof in column action to spread the same, tension the membrane, and close the prongs, said spreader being further adapted in alternate position to engage the outside faces of the rockable members near said other edges to draw the rockable members together, ex the membrane, and open the prongs.

6. A binding unit for sheets having perforations at one edge, the unit comprising: a pair of elongated complementary rigid rockable members each having spaced longitudinal edges, the one set of complementary edges of said rockable members defining inner and outer ways on their inner and outer surfaces respectively; means defining rigid interrupted prongs on at least one rockable member extending between the other edge of one rockable member and the other edge of the other rockable member, said prongs being adapted to pass through the perforations of the sheets and in closed position defining a hook that resists closing movement of said one edge; a thin flexible membrane joining the rockable members intermediate their edges; a slide defining inner and outer Ways complementary to and slidable upon the outer and inner ways, respectively, of the rockable members, the slide serving with its outer ways bearing on the inside ways of the rockable members to spread the rockable members, tension the membrane, and close the prongs, the slide being further adapted with its inner ways on the outer ways of the rockable members to draw the rockable members together at their edges opposite the prongs, ex the membrane, and open the prongs.

7. An extrudable one piece binder part adapted to receive a plurality of sheets with holes on one edge, said binder part being of homogenous material and defining a pair of elongated spaced relatively thick rigid complementary members each having spaced parallel edges, a relatively thin flexible tension-resisting web joined integrally to said members intermediate said edges and extending substantially the length of said members to hold the same in longitudinal alignment, said binder part further defining relatively thick prongs integral with at least one of said members and forming C-shaped interrupted hook-like sheet-receiving structures etxending between one edge of one of said members and the corresponding edge of the other of said members to open when the members are rocked in one direction relative to each other and to resist movement of said members when rocked beyond prong-engaging position in the opposite direction, said members being adapted to receive a spreader member near the other edges of said members to spread the members in prong-closing direction, tension the Web, and hold the binder part in closed sheet-retaining position.

References Cited in the file of this patent UNITED STATES PATENTS 2,425,205 Raynolds Aug. 5, 1947 FOREIGN PATENTS 7,081 Great Britain Mar. 21, 1910