US 3901134 A
A trailing edge folder assembly is provided suitable for ready connection with a previously available folder-gluer machine having the capability of only folding the lateral edges of a box blank being operated on. This assembly comprises means for sensing the location of a box blank along the folder-gluer machine; means for activating an endless operating loop to which are pivotally attached folding fingers; and means for pivoting these fingers when they are in a suitable juxtaposition to a box blank to be folded so as to cause the folding finger to contact and fold over the trailing edge of a box blank, the folding fingers moving in a direction substantially parallel to that of the box blank and at substantially the same speed. The apparatus further comprises means for halting the movement of the endless operating chain upon completion of the folding operation on a particular box blank and prior to the passage of a succeeding box blank.
Claims available in
Description (OCR text may contain errors)
United States Patent Reizenstein et al.
[ 1 Aug. 26, 1975 SELF-SYNCHRONIZED TRAILING EDGE FOLDER ASSEMBLY ACCESSORY FOR FOLDER-GLUER Filed: June 28, 1974 Appl. No.: 484,160
Primary Examiner-Roy Lake Assistant ExaminerJames F. Coan Attorney, Agent, or FirmLilling & Siegel [5 7 ABSTRACT A trailing edge folder assembly is provided suitable for ready connection with a previously available foldergluer machine having the capability of only folding the lateral edges of a box blank being operated on. This assembly comprises means for sensing the location of a box blank along the folder-gluer machine; means for  US. Cl. 93/49 AC; 93/49 R activating an endless operating loop to which are piv-  Int. Cl. B3lb 1/54 otally attached folding fingers; and means for pivoting  Field of Search 93/49 R, 52, 49 M, 36 R, these fingers when they are in a suitable juxtaposition 93/45, 48, 49 AC; 53/374 to a box blank to be folded so as to cause the folding finger to contact and fold over the trailing edge of a  References Cited box blank, the folding fingers moving in a direction UNITED STATES PATENTS substantially parallel to that of the box blank and at 2349 204 5,1944 Staudc 93,49 R substantially the same speed. The apparatus further 2839'972 6/1958 93/49 R comprises means for halting the movement of the end- 312291596 1 H966 Hottendorf.......:: M: 93/49 R less operating chain upon completion of the folding 3,330,185 7/1967 Annett ct al. 93 49 R Operation On a Particular bOX blank and Prior to the 3,377,926 4/1968 Propper 93/49 R passage of a succeeding box blank. 3,377,927 4 1968 P 93 49 R topper 13 Claims, 8 Drawing Figures 53a. f? v I fla- 55 /4 80 5s 67 0 3i, 0 000 000000 eero F'\ 7 T R 50) l JL L l 1 I 32 5 s 52 u J0\ a Q L I l, q 6 0 0 5 5 39 44 54 52 PATENTED AUE 2 6 I975 SHIT 2 OF 4 PATENTED AUG 2 6 I975 saw 3 BF 4 SELF-SYNCHRONIZED TRAILING EDGE FOLDER ASSEMBLY ACCESSORY FOR FOLDER-GLUER A box blank folding assembly apparatus is provided which can be added as an accessory to conventional, presently available folder-gluers in the box industry. Many of the less expensive folder-gluers available on the market today have no provision for manufacture of folding cartons with four folded, glued flaps. Specifically, they do not have the capability of folding over the rear, or trailing, edge of a carton blank as it passes down the apparatus line. Such a deficiency has been overcome, in one instance, by combining two of these relatively inexpensive machines at a 90 angle, to form what is known as an L-Gluer in the trade, in which the boxes move from a first machine, where the side edges are folded, to the second machine, which being at a right angle, automatically transforms the leading and trailing edges in the first machine to the side edges in the second machine. A more sophisticated apparatus is provided by the so-called Excelldevice, in which the box blanks lock onto dogs on a continuously moving chain. The chain is indexed and calibrated to a Geneva mechanism which in turn actuates the folding fingers for the trailing flap. Such a device is extremely expensive, requiring a sophisticated actuating mechanism which must be reset by changing the relationship of the dogs on the chain drive to the Geneva mechanism when blanks of a different size are provided. Such a device is shown, for example, in U.S. Pat. No. 3,330,185 to Annett et al. Also see U.S. Pat. No. 2,349,204 to Staude.
Yet another method for folding trailing flaps uses a rather unconventional, variable speed drive mechanism for an endless carrier, i.e. a link chain, to which are attached a plurality of non-pivoting folding fingers.
An over-head type of folding mechanism is shown in U.S. Pat. No. 3,377,927 to Propper.
In accordance with the present invention, apparatus is provided which can be added as an accessory to conventional folder-gluer machines presently available to the trade and which economically increases the capability of such machines so as to enable them to fold the trailing edges of cartons and thus upgrade their value to substantially that of the far more expensive chainsynchronized, Geneva-drive operated folding apparatus. The apparatus of the present invention is designed and adapted to be operatively connected to and held within conventional box blank-folding apparatus comprising box blank moving support means, such as a belt, and main drive means for the support means; the apparatus of this invention comprises: clutch means, operatively connected to the main drive means; secondary drive means operatively connected to the clutch means; an endless operating loop driven by the secondary drive means, located wholly below, but alongside of, the moving support means; the endless operating loop comprises a substantially straight upper section extending substantially parallel to, but beneath, the moving support means, and a curved end portion at each end of the straight section; first sensing means, located adjacent the moving support means, sensitive to the position of the trailing edge of a box blank moving along the support means; signal means activated by the first sensing means and operatively connected to the clutch means so as to engage the clutch and thus initiate the motion of the endless operating loop when the trailing edge of the blank reaches a predetermined position along the support means; folding fingers, pivotally connected to the endless loop so as to move with the endless loop but biased towards a rest position with respect to pivotal motion, and having a cam follower surface rigidly connected to each folding finger; a cam surface, stationary with respect to the support means and the endless loop, located adjacent the endless loop and so positioned that when the cam surface contacts the cam follower surface, the respective folding finger is caused to pivot in an upward direction, above the level of the support means so as to contact a box blank adjacent the trailing edge thereof; a second sensing means adjacent the endless loop and sensitive to the position of the folding finger; and second signal means, activated by the second sensing means and operatively connected to the clutch means so as to disengage the clutch, and thus halt the motion of the endless loop when the folding finger is aligned in a predetermined position.
In its operation, the folding finger is caused to pivot upwardly into contact with the rear, or trailing flap of the blank, causing the trailing flap, which has previously been scored, to fold upwardly and over, along the scored line, for about or until the flap is held against the body of the box blank. Once that position is reached, the cam follower surface has moved out of contact with the cam surface and the biased folding finger pivots back to its rest position, thus releasing the folded flap and moving out of the way of the moving support means so as not to interfere with the further movement of the box blank. Preferably, 'an external guide member is provided, located above the support means, which holds the trailing flap in its folded position after the folding finger is removed.
Preferably, there are two equidistant folding fingers on the loop, and the second signal means is set to disconnect the clutch and halt the motion of the loop when the second folding finger is in the ready position, i.e. its cam follower surface is immediately adjacent the cam surface.
In the operation of the folding mechanism of the present invention, it will be appreciated that any number of folding fingers may be utilized so long as not more than one extends above the belt line at any one time. In the preferred example described herein, two folding fingers are illustrated. Further, the endless loop can be formed of a minimum size so that substantially any size box blank can be handled without requiring any substantial mechanical change to the machine. Even the smallest blanks can be handled; it is only necessary to space the blanks sufficiently to permit the complete operation of the folding fingers, as will be seen from the more complete explanation of the operation of this invention set out below.
The endless operating loop preferably comprises two curved end portions defining a particircular path about an axis of rotation perpendicular to the direction of movement of the moving support means. The upper straight portion of the operating loop moves in the same direction as the support means and at substantially the same velocity. The endless support loop preferably defines a plane normal to the support means and extending parallel to the direction of movement of the support means.
A preferred embodiment of the present invention is shown in the accompanying drawings and described in the following specific description of the invention.
. it must be understood, is not confined to the features which are shown therein. Various modifications, alternatives and equivalents can be made or substituted for the exact features shown herein. Various other embodiments of the invention may be adapted within the scope of the claims.
Referring to the drawings:
FIG. l is a top view of a portion of a box blank folding apparatus showing the locations of the trailing edge folding apparatus of the present invention;
FIG. 2 is a sectional view taken along lines 2-2 of FIG. 1, along the direction of the arrows;
FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2 in the direction of the arrows;
FIG. 4 is a sectional view taken along lines 44 of FIG. 2 in the direction of the arrows;
FIG. 5 is a side elevation view of the folding finger for the apparatus of the present invention;
FIG. 6 is a magnified sectional view taken along lines 6-6 of FIG. 5 in the direction of the arrows;
FIG. 7 is a magnified sectional view along lines 77 of FIG. 5, taken in the direction of the arrows; and
FIG. 8 is an example of a block diagram of the sensing and control system for the present invention.
In the drawings, the invention is exemplified in its preferred environment of a typical box-blank folding machine known to the art as a folder-gluer, such as is manufactured by the Post Co. and International Paper Box Machine Co. Only a portion of this folding machine is shown, as the remainder of the machine is conventional in the art and its details are not a part of the present invention. In its general operation, a box blank is carried along by means of friction contact between belts placed above and below the blank and biased against the blank, for example, by spring loaded idlers. In the portion shown, only a single lower belt is actually illustrated. However, an upper belt is present along the remaining portion of the apparatus. The lower support belt and the upper holddown belt are conventional support means and form no part of this invention. Generally, the box blank line operates along a horizontal pass and box blanks are fed to it from a magazine not shown. A plurality of folds can be made simultaneously or successively in the blank as it advances along the line in the direction of the arrows, in FIG. 1. In the present invention, it is preferred that the trailing edge fold be made prior to folding the remaining edges of the blank. The trailing flap of the blank lies flat along the supporting belt and preferably is scored so as to permit ready folding or articulation.
The box blank is supported by a lower continuous carrier, which in the embodiment shown, comprises a plurality (two substantially wide belts are shown as an example) of endless conveyor belts 12, the top surfaces of the belts forming a substantially horizontal plane and are separated by a distance sufficient to contain the folding mechanism of the present invention. The box blank 10 is carried along between long continuous belts 12 in frictional contact with the upper and lower surfaces of the blank 10. Along most of the line, an upper belt is held against the box blank by spring-loaded idler rollers, not shown. The variable drive mechanism for the continuous belts 12 also continuously operates a timing belt or chain; in the example shown herein, a roller drive chain 16 via a drive sprocket 17. The drive roller chain 16 drives an input sprocket 18, which is in turn operatively connected so as to drive an input shaft 19 to, in this case, an electromagnetic clutch-brake, generally indicated by the numberal 20. A counting sprocket 22 rotates together with the input sprocket 18. The evenly spaced teeth on the counting sprocket 22 pass in a counting relationship to a magnetic pick-up unit, generally indicated by the numeral 24. The counting sprocket 22 must be of a magnetic material, for example common steel.
The output shaft 26 from the electromagnetic clutch brake 20 is in turn operatively connected, via a flexible coupling 28, to a keyed drive shaft 32, which in this case is square. The keyed drive shaft 32 drives the flapfolding mechanisms, generally indicated by the numeral 30.
As shown in FIG. 1, a plurality of flap-folding mechanisms 30 can be provided intermediate the plurality of coplanar continuous carrier belts 12, so as to act against the trailing flap of the blank 10 at several locations along the width of the blank 10.
To connect the folder mechanisms of the present invention into a conventional folder-gluer apparatus, a plurality of alignment bars 34, 36, are rigidly attached to the frame of the folder-gluer, and'the folder assemblies are mounted on the alignment bars. Referring to FIGS. 1 and 2, the frame 40 of each folder assembly 30 is mounted via two generally circular openings therethrough, onto the alignment bars 34, 36, along which the frame 40 may slide until it is properly positioned intermediate two of the carrier belts 12. When the folder mechanisms 30 are properly positioned, they are then locked in the correct position, utilizing set screws 39, acting against the alignment bars 34, 36.
The keyed (square) folder drive shaft 32 is keyed within a complementary opening through driving sprocket 42, which is in turn connected to an endless operating loop, e.g. roller chain 44; the roller chain 44 is also mounted on a follower sprocket 46. Mounted upon the roller chain 44, at opposing positions, are two folding dog links 50, 51. Onto each of the dog links 50, 51, there is pivotally mounted a dog 52, 53. Each of the dogs 52, 53 is biased towards the rest position shown for dog 52 in FIG. 2, by a torsion spring 54 connected between the dog 52 and dog plates 55, 56, each rigidly mounted onto their corresponding dog links 50, 51. Each of the dogs 52, 53 pivots about a dog shaft 58 on ball-bearing 60. The dog shaft 58 projects through the dog plate 56 and is held in place by a pin 57. Each of the dogs 52, 53 in its rest position, is biased against a stop pin 61 by the spring 54.
Lateral deflection of the folding dogs 52, 53, or of the dog plates 55, S6, is prevented by retaining, e.g., plate 56 and link 51 between a lower chain guide 65 and an upper guide plate 67. A guide track defined by concave surfaces 68 on the guide plate 67 holds an upwardly protruding finger 69 from the dog plate 56 to prevent lateral movement of the dog 53 in the event that any uneven torsion is applied to any portion of the dog or the chain during the folding operation.
Cam rollers 70, 71 and 72 are connected to the chain guide 65 in a position so as to contact, e.g, the tail surface 53b of the dog 53, as shown in FIG. 2.
Box blank guides are located vertically above the folder mechanism, at a location just beyond that of the roller cam 72, so as to catch and hold the folded-over trailing edge of the box blank as it leaves the folder mechanism.
A second magnetic pick-up 84 is attached to the folder frame 40 in a position so as to be adjacent the, e.g., tail 53b of the dog 53 as it passes the follower sprocket 46. The first and second magnetic pick-ups 24, 84, both operate by generating an electrical pulse when placed in a certain proximity to magnetic material. The first magnetic pick-up is sensitive to the steel teeth on the counting sprocket 22 and has a variable setting to activate an output electrical impulse as soon as a pre-set number of magnetic teeth have been counted. This setting can be varied as desired. The second magnetic pick-up 84 emits an electrical impulse upon the passage of the magnetic material forming the, e.g., end of shaft 58. Both magnetic pick-ups are connected to a conventional electronic control mechanism by conductor means not shown. The electronic control mechanism in turn energizes the clutch-brake 20 upon receiving an impulse from the first magnetic figure 24 and de-energizes the clutch brake 20 upon receiving an impulse from the second magnetic pick-up 84. The exact mechanism and method of operation of the electronic controller and the electromagnetic clutch brake are conventional and are therefore not shown in order to avoid unnecessary and probably confusing detail which would tend to obfuscate the description of the present invention.
A photocell 90 is located at a position perpendicularly above the space between the conveyor belts 12 and is designed and adapted to be activated by the interruption of light from below, caused by the passage of the box blank over the conveyor belts 12. When the box blank passes beyond the cell 90 and light is once again passed to the cell, an electronic impulse is sent to the magnetic pick-up 24, again by means not shown but conventional in the art, to initiate its counting.
In operation, a plurality of folder units are aligned on the alignment shafts 34, 36 and locked in place by set screws 39. Blanks are fed by conventional mechanisms onto the continuous carrier belts 12. Preferably, the folding of the rear or trailing flap utilizing the apparatus of the present invention is the initial step in the preferred system. However, if desired for other reasons, the rear flap folding mechanism can be set anywhere along the folder-gluer conveyor line, intermediate the side folding means or after the side folding means have been activated.
As the box blank passes along the conveyor belt, it passes beneath the photocell 90, interrupting the light, and then as it goes beyond photocell 90, the light is once again directed at the cell which sends out an impulse to the magnetic pick-up 24. The drive chain 16 is being continuously driven by the same drive mechanism operating the belts 12 and in turn also drives the counting sprocket 22. The impulse from photocell 90 activates the magnetic pick-up 24, which has in turn been pre-set to count a certain number of teeth on the sprocket 22. The number of teeth counted permits the box blank 10 to advance to the correct location and also compensates for the magnetic time constant of the electromagnetic clutch-brake 20. After a predetermined number of teeth have been counted, a magnetic pulse is sent out by magnetic pick-up 24, thus indicating that the box blank is in the position ready for folding; the pulse is transmitted by magnetic pick-up 24 to the electronic controller, not shown, for the electromagnetic clutch brake 20, which in turn activates the electromagnetic clutch brake 20, thus causing the rotation of the keyed (square) drive shaft 22, via flexible coupling 28, in turn driving the drive sprocket 42 and the endless roller chain 44.
The folder assembly 30 has been in a rest position up until that time; the dog 53 is at a position immediately above the drive sprocket 42; and the dog 52 is at a position immediately beyond the follower sprocket 46. The dog 53 is in the stop position, shown by the solid lines of FIG. 5. Upon activation of the folder mechanism, and movement of the roller chain 44, the cam follower surface 53b of the tail of the dog 53 impinges against the first cam roller as the roller chain 44 continues to move, the dog 53 is caused to pivot in a clockwise direction into the various positions shown by the phantom lines of FIG. 5 and through the position shown in FIG. 2, the folder surface 53a of the dog 53 pushing upwardly against the trailing flap of the box blank 10, causing it to fold upwardly, as shown in FIGS. 2 and 5. The suceeding cam roller surfaces 71 and 72 continue to pivot the dog 53 until it is in the final position shown in FIG. 5, in which position the trailing edge of the blank 10 is in a completely folded over position.
When the folding surface 53a of dog 53 pushes upwardly against the trailing edge of the blank 10, the folding is accomplished at a prescored line of articulation 10a, previously formed on the box blank. The remaining portion of the box blank is held in a position substantially flat against the belt 12 by the upper belts (not shown) acting downwardly against the forward portion of the remainder of the box blank. As shown, the box blank guide is fixedly disposed above the surface of the box blank 10 and has an upwardly rounded forward edge such that the guides forward edge readily receives and guides the folded over portion of the trailing edge beneath the guide when the trailing edge reaches that location on the belt 12.
As the follower surface 53b of the dog 53 moves out of contact with the final cam roller 72, the biasing action of the torsion spring 54 moves the dog 53 back towards its rest position, i.e. causing it to rotate counterclockwise, and to return to its position where it is held stationary against stop pin 61. This releases the overfolded portion of the box blank 10, which, however, at this point is held in its over-folded position by the box blank guide 80. The dog 53, in its stop position, rests completely below the lower surface of the paper, i.e. the upper surface of belt 12, and therefore passes beneath the folded-over box blank 10. The chain continues to move the dog 53 around the follower sprocket 46. As the end of shaft 58 and portion of the dog link passes the second magnetic pick-up 84, a voltage pulse is generated which activates the electronic controller and in turn disconnects the clutch-brake 20, causing an immediate braking of the drive chain 44, halting the dog 52 in the ready position, such that the folding surface 52a is immediately below the paper line and the tail surface 52b, immediately adjacent the first cam roller 70. The folding apparatus is thus in position to go through another folding cycle upon the activation of the photocell by the passage of another box blank 10 carried by the continuous conveyor belts 12.
Accordingly, the apparatus in accordance with this present invention, permits the addition of a trailing edge folding capability to a conventional folder-gluer machine without substantial change to the machine.
This apparatus compensates for the slippage of a box blank on a friction belt driven machine and can thus accurately fold a rear or trailing flap of a box blank without the need of a complex timing chain drive, such as a Geneva drive, used in the commonly available trailing flap folding means for edge folding devices. The trailing edge folder of the present invention can be readily inserted into a conventional folder-gluer for a minimum of expense and down-time of the folder-gluer.
The particular sensing apparatus or elements shown in the apparatus of the present invention described above are merely exemplary of various types that can be utilized and the invention is not limited to these particular sensing means. For example, a photocell is not the only means of sensing the passage of a box blank and the method of counting the time elapsed after the passage of the box blank utilizing a timing gear sprocket can similarly be replaced by a known equivalent or an equivalent sensing means to be devised in the future. It is only necessary that the passage of the box blank be sensed and that means be provided for determining the distance travelled subsequent to the passage so as to determine precisely when the folding finger is to be activated.
Similarly, the halting of the endless operating loop can also be carried out utilizing a different type of sensing and signaling means. It is unnecessary to directly sense a location of the folding finger and, for example, the sensing means can be set to directly sense, for example, the location of the folded trailing edge of the box blank. Alternatively, the location of the folding finger can itself be sensed by means other than the magnetic sensing means described above, e.g. a photocell. Examples of other sensing and control devices include electrical proximity or pneumatic sensors, fluidic or other sensitive switches of a mechanical nature.
As stated, an advantage of the present invention is that the folding apparatus can be readily substituted into substantially any of the conventionally available commercial folder-gluer machine without any substantial modification of the other portion of the machine. The size of the endless operating loop can be made so as to be able to handle substantially any size of box blank, limited only perhaps to excluding certain of the extremely small size boxes, e.g. of the pill box size. For example, the length L between the axes of rotation of the drive sprocket 42 and follower sprocket 46 can be between about 7% and 9 /2 inches and optimally about 8% inches; the internal radius, r, of the curved portion at the forward end, i.e. around follower sprocket 46, can be about eleven-sixteenths of an inch, and the radius, R, of the curved portion at the rear end of the endless operating loop 44., i.e. about drive sprocket 42, is about 1 3/16 inches. Each of the folding fingers, as shown there are two in the embodiment in the drawing, include a cam follower surface and a folding surface, substantially parallel to each other. The folding surface 53a must be sufficiently long so as to be able to contact the trailing flap of the box blank while folded completely over through the pivoting positions shown in FIG. 5. Generally, the distance A, from the axis of rotation of the folding finger, e.g. 53, to the nearest portion of the folding surface 53a, is limited by the thickness of the material used in the box blank, e.g. cardboard. Conventionally, the distance A is approximately threefourths inch for a conventional cardboard having a thickness of about one sixty-fourth to about onesixteenth inch.
The cam surfaces 70, 71 and 72 are shown as independent rollers; however such rollers can be substituted for by a single straight cam surface of the same length, i.e. extending from the initial surface of to the end of surface 72. However, such a single surface would result in excessive frictional wear of the cam follower surface 53b and is thus not as desirable. In the example shown, the cams 70, 71 and 72, each have a diameter of about eighths of an inch and the distance from the center of the first cam 70 to the last cam 72 is about 2.5 inches. Such distance, of course, being a function of the length of the straight section of the inlet loop and the distance between the axis of rotation of a folding finger 52, 53 and the top surface of the moving support means 12. As shown, the folding finger has an additional cut-out portion extending beyond the axis of rotation, along the folding surface 53a, in order to avoid contact of the folding finger with the apex 10a of the over-folded trailing flap. This also is determined by the maximum thickness of the blank to be folded.
The particular embodiments shown herein and the alternatives suggested are merely intended to be exemplary of the preferred embodiments of the present invention. They are not to be taken as exclusive of the full scope of the invention, which is set forth in the following claims.
The patentable features of the present invention which are claimed are as follows:
1. A trailing edge folding accessory apparatus for use in combination with a box blank folding machine having support means for continuously advancing along a horizontal path in said folding machine, a box blank at a predetermined speed and in a predetermined direction; primary drive means for said support means; and folding means for folding the lateral edges of a moving blank along a fold-like parallel to the direction of travel, the accessory apparatus being adapted for folding the trailing edge of the box blank forwardly along a line perpendicular to the direction of travel, the accessory apparatus comprising:
an endless operating loop having a substantially straight upper stretch extending substantially parallel to but beneath said path and being adapted to be intermittently operatively connected to the primary drive means;
means for supporting said operating loop in a plane normal to said predetermined path but extending in the same direction;
first sensing and signal control means, including a first portion designed and adapted to be sensitive to the location of a box blank along the said path relative to the location of the operating loop and a second portion for causing the operative connection to be made between the operating loop and the primary drive means so as to initiate motion of the endless operating loop when a box blank is in a predetermined location along the said path;
at least one folding finger, pivotally connected to the endless operating loop, and comprising a folding surface and biasing means for biasing the folding finger towards a rest position;
camming means for causing the pivotal rotation of the folding finger when the folding surface is in a position adjacent the path of a box blank so as to pivot the folding surface in the direction of travel of a box blank as the folding finger moves along the straight upper section of the endless operating loop and for releasingthe finger when the box blank has been folded to a predetermined position, thus permitting the folding finger to be biased back towards its rest position; and
second sensing and signal control means adapted to be sensitive to the completion of the folding operation by the folding finger and to interrupt the connection between the primary drive means and the operating loop so as to halt the motion of the operating loop without interrupting the continued movement of a box blank along its predetermined path.
2. The trailing edge folding apparatus of claim 1, wherein at each end of the substantially straight upper stretch of the operating loop, there is provided a curved particircular portion, having an axis of rotation transverse to and beneath the aforesaid path.
3. The trailing edge folding apparatus of claim 2, wherein the camming means comprises a cam surface fixed with respect to the axes of rotation of the endless loop and a cam follower surface rigidly connected to the folding finger, whereby when the cam follower surface contacts the cam, the folding finger is caused to pivot in the direction of the path of the box blank and contact between the follower surface and the cam is maintained for a period sufficient to substantially overfold the trailing edge, at which point cam contact ends and the finger is released.
4. The trailing edge folding apparatus in accordance with claim 1, wherein the first sensing and signal control means comprises control means adapted to intermittently operatively connect the primary drive means to the operating loop, and signal means operatively connected to the sensing means adapted to activate the control means upon the box blank reaching the predetermined location.
5. The trailing edge folding apparatus of claim 4, wherein the first sensing means comprises lightsensitive means for visually sensing the location of the box blank.
6. The trailing edge folding apparatus of claim 1, wherein the second sensing and signal control means comprises a second sensing means sensitive to the location of the folding finger, subsequent to its returning to the rest position, second signal means responsive to the sensing means and adapted to signal the control means to disconnect the primary drive means from the operat ing loop.
7. The trailing edge folding apparatus of claim 5, wherein said first sensing means comprises lightsensitive means for visually sensing the location of the trailing edge of the box blank.
8. The trailing edge folding apparatus in accordance with claim 7, wherein the first signal means comprises in addition, means for activating the control means a predetermined interval of time after the light-sensitive means visually senses the location of a box blank, the predetermined time being determined by the speed of travel of the box blank along its predetermined path.
9. The box blank folding apparatus of claim 2, wherein the operating loop is a link chain.
10. The trailing edge folding apparatus of claim 1, wherein the biasing means is a spring.
11. The trailing edge folding apparatus of claim 1 comprising secondary drive means adapted to intermittently connect the primary drive means to the operating loop, the secondary drive means comprising clutch means having a driven side and a driving side, the driven side adapted to be connected to the primary drive means and the driving side connected to the operating loop, the clutch being operatively connected to the control means for intermittently operatively connecting the primary drive means to drive the operating loop.
12. The trailing edge folding apparatus of claim 1 comprising two folding fingers.
13. In combination with a box blank folding machine comprising:
a moving support means for moving a box blank in a predetermined direction of travel; primary drive means for the moving support means; and side folding means for folding the side edges of the moving blank along a line parallel to the direction of travel;
accessory apparatus for folding the trailing edge of the box blank forwardly along a line perpendicular to the direction of travel, the accessory apparatus comprising:
alignment means for maintaining the accessory appa ratus in a fixed position relative to the moving support means;
an endless operating loop rotatively connected to the alignment means and having a straight upper section located lower than and adjacent to, and parallel to the moving support means;
secondary drive means for the accessory apparatus operatively connected to the primary drive means;
connecting means operatively connected to the secondary drive means;
control means for intermittently operatively connecting the connecting means to the endless operating loop;
first sensing and signal means located adjacent the moving support means and sensitive to the position of the trailing edge of a box blank moving along the support means, and operatively connected to and designed and adapted to activate the control means;
a folding finger, pivotally connected to the endless oprating loop, comprising a folding surface extending transversely outwardly from the endless loop and a cam follower surface extending transversely inwardly from the endless operating loop, the cam follower surface and the folding surface being rigidly connected;
biasing means for biasing the folding finger towards a rest position;
cam means stationary with respect to the alignment means and adjacent to the endless operating loop so positioned as to contact the cam follower surface of the folding finger when the folding surface is in a position adjacent the moving support means so as to pivot the folding finger in the direction of travel of the support means as the folding finger travels along the straight upper section of the endless operating loop;
box blank guide, located immediately above and adjacent to the moving support means and resiliently biased towards the support means so as to accept and hold in place the box blank as it moves along the support means, including the over-folded trailing flap, once it has been over-folded; and
ots in response to the contact between the cam means and the cam follower surface and the folding surface moves out of contact with the over-folded box blank when the cam follower surface of the folding finger moves out of contact with the cam means by pivoting to its rest position below the support means, at which point the endless operating loop is halted.