US2910729A - Procedure and apparatus for making a binding element having nested fingers - Google Patents

Description

NOV. 3, 1959 LL ETAL 2,910,729

PROCED AND APPARATUS F MAKING A BINDING EMENT HAVING NESTED FINGERS Filed Aug. 5, 1957 2 Sheets-Sheet 1 ii as 2526 32 241 20 a 3y d 22 HEATED FLA TEN (3) W36 IN VENTORB Jamey Z.

NOV. 3, 1959 ,F% M ETAL 2,910,729

PROCEDURE AND A P RATUS AKING A BINDING ELEMENT VING NESTED FINGERS Filed Aug. 5, 1957 2 Sheets-Sheet 2 INVENTORS IfOfiZZ SU 20 W37 j jif pazzcajz My, W, was

United States PatentO PROCEDURE AND APPARATUS FOR MAKING A BDIDING ELEMENT HAVING NESTED FINGERS John Schaller, Jr., Norridge, Henry Than, Chicago, and James K. Duncan, Park Ridge, 11]., assignors, by Inesne assignments, to American Photocopy Equipment Company, Chicago, 111., a corporation of Illinois Application August 5, 1957, Serial No. 676,179

9 Claims, (Cl. 18-19) The present invention relates to plastic bindings and more particularly to the making of a binding element in which the fingers are all tucked or nested inside of the backing portion.

Binding elements of the type disclosed in Douvry US. Patent 1,970,285 and made of thermoplastic material or the like are conventionally supplied to the user with the fingers curled outside of the backing portion, giving rise to a number of problems. In the first place, the elements are usually shipped loose in boxes of a hundred or more. During packing and transport, and prior to the time that the bindings are separated from one another, the tips of the binding fingers tend to hook onto the tips and backings of adjacent bindings with the result that the binding elements become tangled and difiicult to separate. Moreover, during the course of attempted separation, the fingers may be bent outwardly beyond the elastic limit, requiring the binding elements thus deformed to be discarded. Moreover, modern binding machines have a reservoir in which a number of bindings are stored just prior to use and manipulated into binding position with the operators finger tips. The tangling of the binding elements at the point of use tends to interfere with binding on a rapid production line basis and is a source of annoyance and frustration to the operator.

Accordingly it is an object to provide a novel procedure and apparatus for causing the binding fingers to be transferred from the outside position overlying the backing portion to a tucked or nested position inside of the backing portion where the tips of the binding fingers are shielded against catching on adjacent bindings.

It is another object to provide a novel integrated manufacturing procedure employing a headed forming mandrel and in which the binding fingers are transferred into the nested position automatically incident to removal of the binding element from the mandrel and without necessity for a separate tucking operation. It is a further object to provide apparatus for carrying out such procedure on a high quantity production basis.

It is still another object to provide a novel mandrel construction which causes the binding fingers to be sequentially spread into a position clear of the backing portion and deposited in-nested position inside of such backing portion, in a positive and uniform fashion. It is moreover, an object of the invention to provide a procedure and apparatus which makes use of elastic forces characteristic of a thermoplastic binding element which has been formed by rolling in the heated condition.

Finally it is an object to provide a binding element in which the backing portion is clear and available for silkscreening or other printing or decorating process.

. Other objects and advantages of the invention will become clear upon reference to the attached detailed description and upon reference to the drawings in which:

Figure 1 shows, in simplified diagrammatic form, a type of rolling machine which may be employed in pracdoing the present invention.

Fig. 2 shows a typical binding element blank having a series of fingers and an integral lacking portion.

Fig. 3 is an enlarged fragmentary view showing partial rolling of a binding element.

Fig. 4 is a fragmentary view similar to Fig. 3 but show ing the completion of the rolling operation.

Fig. 5 is a foreshortened view of a mandrel used in the machine of Fig. 1 with a binding element rolled thereon.

Fig. 6 is an enlarged section taken along the line 6-6 in Fig. 5.

Fig. 7 is an enlarged perspective showing the tip portion of the mandrel disclosed in Fig. 5.

Fig. 8 shows a mandrel with a binding element formed thereon together with means for stripping the element endwise. v

Fig. 9 is a fragmentary stop motion view showing a binding finger at the region of drop-oil.

Fig. 10'is a section taken along the line 10'-10 in Fig. 9.

Fig. 11 is a stop motion View showing the first finger in a nested position following drop-01f.

Fig. 12 is a section taken along the line '1212 in Fig. 11.

Fig. 13 shows a portion of the completed binding with the fingers in nested position.

Fig. 14 is a view similar to Fig. 7 but shows the head formed by longitudinal splitting of the end of the mandrel.

Fig. 15 shows an alternate form of the invention employing an enlarged tip of spherical configuration.

While the invention has been described in connection with certain preferred embodiments, it will be understood that we do not intend to limit the invention to such embodiments but intend to cover the various equivalent and alternative constructions falling within the spirit and scope of the appended claims.

Turning to the drawings, Figure 1 shows in simplified and partially diagrammatic form a rolling machine applicable to the present invention and capable of handling a binding element blank, the profile of which is set forth in Fig. 2. The blank indicated generally at 20 has a series of fingers 21-24 integrally connected to a backing portion 25 and having a straight edge 26. It will be apparent to one skilled in the art that a typical backing element includes a much largernumber of integral fingers and that the fingers 21-24 simply constitute the first four fingers in the series. The blank 20 may be made of any suitable thermoplastic material, such as cellulose acetate, capable of being readily deformed when heated and capable of acquiring a more or less permanent set when restored to room temperature.

The rolling machine indicated at 30 includes a series of rollers 31,- 32, 33, 34 over which is trained a belt or blanket 35 which may be formed of heat resistant fabric, for example, treated cotton. The belt 35 is shown as endless, although it will be apparent as the discussion proceeds that the invention is not limited to the use of an endless belt and that a cyclically reversing two-ended belt may be used if desired. Mounted directly below the horizontal pass of the belt is a heated platen 36 for heating the binding element as it passes by. The roller 32 above the heated platen defines a rolling station. 39 having a mandrel or rod 40, about which the belt 35 makes a pass of preferably more than one-half revolution.

The operation of the device will be apparent from Figs. 3 and 4, taken in connection with Fig. 1. An element 20 is placed upon the belt 35 with the edge 26 in leading position, and as the belt is advanced in the direction of the arrow by a' suitable driving means, the backing portion engages the mandrel 40 and is trapped between it and the belt. Upon continued movement of the belt, the v element wraps around the mandrel, assuming a cylindri cal shape as shown in Fig. 3. Since the element 20 is rendered plastic by action of the heat, the leading edge thereof tends to follow the mandrel upon separation of the mandrel and belt. Upon continued rotation of the mandrel and-belt, the fingers of the binding eiement are wrapped around the backing portion 25 assumingthe position shown in Fig. 4 and with the fingers in intimate contact therewith.

In accordance with the present invention, the mandrel 40 has a body portion 41 and an enlarged tip or head 42 as shown in Figs. 5 and 7, the diameter of the headbeing- 'of the body of the mandrel. The tip may be flat or slightly rounded as shown. In accordance with one of the more detailed aspects of the invention the region of dropoff, indicated at 43, is sufficiently abrupt so that the individual fingers are free to drop off the end of the mandrel closely adjacent the region of maximum enlargement. As will become clear as the discussion proceeds, this tends to insure that the fingers will consistently drop into nested position rather than a position on the outside of the backing portion.

With regard to specific dimensions, the head diameter b at the region of drop-off should be at least sufiicient to cause the individual fingers to be expanded circurn: ferentially beyond the edge 26 of the backing portion with an adequate margin of clearance. To accomplish this the head 42 is preferably about one and one-half times the diameter a of the body of the mandrel. Provided that the condition of clearance is achieved, such dimension may be less than one and one-half times and may, for example, be as small as one and one-quarter times the mandrel diameter. With regard-to the upper limit of circumferential expansion, it is desirable to stay well within the elastic limit of the material being acted upon. Thus in a practical case, using material having approximately the characteristics of cellulose acetate, our observations show that the enlargement may have a maximum diameter at region of drop-off on the order of twice the diameter of the mandrel. In short, a useful range of enlargement diameter may be considered to be between 1.25 and 2.00 times the mandrel diameter. a

In the preferred embodiment shown, the transition between the mandrel and the region of maximum enlargement preferably is smooth and gradual. For example, the length of the sloping portion, indicated at c in Fig. 7, may be on the order of twice the mandrel diameter. This provides a mechanical advantage or wedging eifect which is of advantage in breaking the fingers loose from their rolled position and in overcoming the usual surface adhesion between the tips of the binding fingers and the surface of the backing portion engaged by such fingers. When operating at reasonable temperatures, actual fusion between the fingers and the backing does not take place,

but there is, nevertheless, a tendency for the fingers-to 42. This twisting action further insures a low break-away force.

tional detailed aspect 'of the invention may be discussed.

In carrying out the invention, means are provided for axially restraining the mandrel and for applying. axial l Prior to reviewing a typical operating cycle, anaddh' both oi. which are coupled to a drive mechanism 53, for

rotation in the direction shown. It will be understood that such stripping takes place with the mandrel 40 free of the belt 35 and in position to be pinched between the rollers 51, 52. The present invention is not limited to any particular lateral transport mechanism for moving the mandrel 4t) from its rolling position to a roller-engaging position. As an example of a suitable transport de vice reference is made to copending application Serial No. 698,212, filed November 22, 1957.

Referring to Figs. 8 to 13, a typical step by step operating sequence will next be reviewed. In the condition shown in Fig. 8, the rotated rubber rollers 51, 52 have just been engaged, and since the mandrel is restrained against axial movement, the binding element is propelled toward the enlarged tip or head at the end of the man-I drel. When the first finger 21 strikes the tapered portion of the tip 42, it rides upwardly thereon, tending to twist as shown and to expand circumferentially overcoming any tendency of the tip of the finger to stick to the backing. Upon continued movement, the finger Z1 is drawn clear of the edge 26 of the backing portion. When the region of drop-off 43 is reached, the finger is expanded to the fullest degree and immediately thereafter begins to drop, a condition which is illustrated in Fig. 9 and in the sectional view, Fig. 10. As brought out by the latter figure, the curvature of the backing portion 25 tends to increase, approaching, but not equaling, the maximum diameter of the head 42, producing a temporary condition of maximum receptiveness for the tips of the fingers as they are released. This effect extends beyond the end of the head 42 for a short distance for the reason that restoration of the backing from its spread-apart condi tion to the condition of normal curvature cannot occur abruptly but only gradually along its length.

Upon drop-off or release of a binding finger the finger tends immediately to curl inward, i.e., to assume a more tightly curled position indicated by the dotted lines in this figure. As a result of this inward curling the tip of the binding finger moves not only circumferentially but also radially inward to a point where the tip of the finger clears the inner edge of the backing, thereby occupying a nested position inside of the backing rather than simply reassuming a position on the outside of the backing. It is believed that this action is augmented by elastic forces or pre-stress set up in the plastic material as a result of the rolling operation. Observations show that the position which the finger naturally tends to asume is more tightly curled than the position occupied by such finger at the completion of the rolling operation. This is in the nature of a phenomenon and is believed due to the fact that the outer surface of each of the fingers, i.e., the surface in contact with the belt 35 is, as a result of the rolling operation, slightly stretched so that a finger freed from the restraint interposed by the backing portion would tend to move radially inward by a small amount.

In any event, it is believed that the high degree of con sistency and reliability of the present procedure and apparatus is due, to some degree, to the forces set up in the plastic fingers when such fingers are rolled'by apparatus of the general type set forth in Fig. 1.

To continue the operating sequence, the first fingerfzl goes such drop-off, the second finger is being progressively expanded. It is found that the stripping operation of the.

binding element endwise may be accomplished by the rollers 51, 52 or the like at a high rate of speed on the order of 1 to 3 feet per second without having any adverse affect upon reliability. Following completion of the stripping all of the fingers lie in the nested position as shown in Fig. 13, and the element may be ejected directly into a shipping container.

It is of interest to note that in the preferred embodiment of our invention, the tucking of the individual fingers takes place automatically incident to stripping the binding element from the rolling mandrel; in other words, a separate nesting or tucking operation is made unnecessary. It will, however, be appreciated by one skilled in this art that the nesting may take place as. a separate operation if desired. That is to say, a binding element having its fingers engaging the outside of the backing may be threaded on a mandrel and stripped over an enlarged tip at the end thereof as a separate operation.

While the invention has been discussed in connection with the preferred embodiment employing a frustoconical head, the invention in its broader aspects is not limited to such specific construction. The head may be formed, if desired, by splitting and flaring the end of the mandrel body, as shown at 42a in Fig. 14, and the device thus formed operates in substantially the same manner as described. It has also been found that a spherical tip 60 may be employed at the end of the mandrel with good results. The use of a spherical tip is illustrated in Fig. 15. Here it will be noted that the fingers are successively guided up onto the spherical head portion to a point of maximum diameter, following which the fingers are indi vidually dropped olf, or deposited inside of the backing. It would appear that the abruptness of the spherical surface is sufficient to achieve many of the advantages of the preferred form shown in the remainder of the figures.

While the invention is most readily understood in connection with the apparatus discussed above, it will be understood that the invention is not necessarily limited to this specific apparatus but comprises,'in one of its aspects, a series of method steps. The steps include the applying of heat to the bindingelement, the wrapping of the element about a mandrel in the heated state so that the fingers overlie the backing portion and are in contact therewith, expanding the fingers sequentially to clear the backing, and then releasing the fingers sequentially from the expanded condition for nesting within the backing portion of the binding. In a more detailed aspect the method includes the stripping of a rolled binding element over an enlarged tip or head formed on the rolling mandrel.

. Since the expansion and hence break-away of the fingers is accomplished sequentially, the break-away force to be overcome is much less than that encountered in a binding machine where all of the fingers are hooked and expanded together. Even more important, since this break-away is inherent in the present procedure, the resulting binding elements may be spread in a binding machine with light fingertip pressure, a force which is a fraction of that normally required for conventional bindings.

Also of importance is the fact that there is less basis for customer complaint. Thus it sometimes happens that the fingers of a binding element may be rather securely stuck as'a result of using a rolling temperature which is a bit too high. Such elements are sometimes returned as defective. In the present binding, by contrast, each of the fingers is positively freed as a factory operation, and thus each binding element is, in the eyes of the customer, in perfect working order.

Bindings made or processed as described have been found to be free of any tendency to tangle or catch onto one another during packing or shipping, in spite of loose, bulk-packing. Moreover, because of their easy separation, the binding elements have been found to be ideally suited to automated and high speed production line usage.

Andsince the fingers are alltucked inside in the completed binding element, the back portion of the latter is free for silk-screening or the like prior to use of the bindings in a binding machine. One skilled in the art will appreciate that the binding could, if desired, be rolled with fingers leading instead of trailing which would cause the fingers naturally to nest inside the backing portion. However, this procedure is undesirable, particularly in the, case of conventional or wide back bindings, since the fingers tend to embossthe backing and to produce a backing surface which is non-uniform and wavy rather than smooth. Using the present scheme, a smooth cylindrical backing surface is produced having a neat and workmanlike appearance.

We claim as our invention:

1. In an apparatus for making plastic binding elements from blanks having a series of fingers and an integral backing portion, the combination comprising a mandrel, means for heating said blanks, means for rolling a heated blank about said mandrel with the fingers overlying the backing portion and in intimate contact therewith, said mandrel having a body portion and an enlarged head at one end forming a continuation of said body portion, means for anchoring said mandrel against endwise movement, means for applying endwise movement to said element in the direction of said enlarged head, said head having a diameter such that when the binding is passed over the head the fingers are stressed circumferentially clear of said backing portion without, however, exceeding the elastic limit of said fingers so that upon said fingers being moved clear of said head they are free to curl in response to said stress into nested position inside said backing portion.

2. The method of forming a thermoplastic binding element from a flat blank having a series of fingers and an integral backing portion which comprises applying heat to said element, wrapping said element into a cylinder in the plastic state starting with the edge of the backing portion so that the fingers overlie said backing portion and are in intimate contact therewith, expanding said fingers circumferentially in sequence so that the tips thereof are circumferentially clear of the adjacent edge of the backing portion and stressed for inward curling, and then releasing the tips of the fingers in sequence so that the tips of said fingers responding to said stress curl inwardly into nested position inside of said backing portion.

3. The method of forming a thermoplastic binding element from a flat blank having a series of fingers and an integral backing portion which comprises applying heat to said element, wrapping said element about a headed mandrel in the plastic state so that the fingers overlie said backing portion and are in contact therewith, and then applying relative endwise movement to the binding element in the direction of the head on said mandrel so that the fingers are (a) expanded circumferentially in sequence as they pass over said head and (b) released for inward curling into nested position inside of said backing portion as they pass from said head.

4. In an apparatus for making plastic binding elements from blanks having a series of fingers and an integral backing portion, the combination comprising a mandrel, means for heating said blanks, means for rolling a heated blank about said mandrel with the fingers. overlying the backing portion and in intimate contact therewith, said mandrel having a body portion and an enlarged head at one end forming a continuation of said body portion, said head having a gradually enlarged transition with respect to said body portion, means for anchoring said mandrel against endwise movement, and means for applying endwise movement to said element in the direction of said enlarged head so that the fingers of the element sequentially ride up on said head portion until they occupy a positioncircumferentially clear of said backing portion,

'7 said head portion further having a region of drop-off so that said fingers after passing over said head are released to occupy a nested position inside of said backing portion.

5. In an apparatus for making'plastic binding elements from blanks having a series of fingers and an integral backing portion, the combination comprising a mandrel, means for heating said blanks, means for rolling a heated blank about said mandrel with the fingers overlying the backing portion and in intimate contact therewith, said mandrel having a body portion and an enlarged head at one end forming a continuation of said body portion, said head providing a smooth transition with said body portion and having a maximum diameter which is in the range of about 1.25 to about 2.00 times as greatasthe diameter of said body portion, means for anchoring said mandrel against endwise movement, and means for applying endwise movement to said element inthe direction of said enlargedhead so that the fingers of the element sequentially ride up on said head until they occupy a stressed position within their elastic limit but circumferentially clear of said backing portion and thereafter upon continued movement pass over said head for release to occupy a nested position inside of said backing portion in response to said stress.

6. In an apparatus for making plastic binding elements from blanks having a series of fingers and an integral backing portion, the combination comprising a mandrel, means for heating said blanks, means for rolling a heated blank about said mandrel with the fingers overlying the backing portion and in intimate contact therewith, said mandrel having a body portion and an enlarged headat one end forming a continuation of said body portion, said head being of flaring cross section forming'a smooth continuation of the surface of said body portion and increasing to a maximum diameter which is substantially greater than the diameter of the body portion, means for anchoring said mandrel. against endwise movement, and means for applying endwise movement to said element in the direction of said enlarged head so that the fingers of the binding element sequentially ride up on said head portion until they occupy a stressed position circumferen tially clear of said backing portion with subsequent sequential drop-off of said fingers in response to said stress into nested position inside of said backing portion.

7. In an apparatus for making plastic binding elements from blanks having a series of fingers and an integral backing portion, the combination comprising a mandrel, means for heating said blanks, means for rolling a heated blank about said mandrel with the fingers overlying the backing portion and in intimate contact therewith, said mandrel having a body portion and 'an enlarged head at one end forminga continuation of said body portion, means for anchoring said mandrel against endwise movement, means for aplying endwise movement to said element in the direction of said enlarged head, said head being frustoconical in shape providing a gradual transition from the diameter of said body portion to amaximum diameter, said maximum diameter being suffi'ciently great so that upon applying relative endwise movement to said binding element the fingers of the binding element sequentially ride up on said head portion until the tips thereof occupy a position circumferentially clear of said backing portion with subsequent sequential drop-0E of said fingers into nested position inside of said backing portion upon continued movement of said binding element. 7

8. The methods of forming plastic binding elements comprisingtthe steps of forming a plastic binding element'having a series of fingers overlying and in'contact with an integral backing portion around a mandrel body portion having substantially the same diameter as the inside diameter of the binding element and a head portion at one end having a'diameter larger than said body portion and having a gradual transition with respect to said body portionand a drop-0d region, and applying relative endwise movement to the binding element so that the fingers of the element sequentially ride up on said head portion until they occupy a position circumferentially clear of said backing portion and thereafter pass oversaid head to said drop-off region where they are released to occupy a nested position inside of said backing portion.

9. The method of forming plastic binding elements comprising the steps of forming a plastic binding element having a series of fingers overlying and in contact with an integral backing portion around a mandrel body portion having substantially the same diameter as the inside diameter of the blinding element and a headportion at one end ;of flaring cross section forming a smooth continuation of the surface of said body portion and increasing to a maximum diameter which is substantially greater than the diameter of the body portion, and applying relative endwise movement to said binding elements so that the fingers of the binding element sequentially ride up onsaid head portion until they occupy a stressed position within their elastic limit but circumferentially clear of said backing-portion and thereafter sequentially dropoff of said head into nested position inside of said backing portion.

References Cited in the file of this patent UNITED STATES PATENTS 653,491 Torsch July 10, 1900 1,130,030 Sill Mar. 2, 1915 1,353,714 Bohling Sept. 21, 1920

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