Box closing apparatus
BACKGROUND OF THE INVENTION 
     The present invention is an apparatus for closing the type of box that has a cover hinged to the body portion and is locked in closed position when the cover is swung over onto the body portion and flanges that extend out from the front edges of the cover and body portion, respectively, are pressed together so that one or more projections or buttons on one of the flanges is forced into mating well or wells in the other flange and snaps into locked relation therein. This type of locking means is sometimes referred to as a press-button snap lock closure. 
     These types of boxes on the the press-button snap lock type of closures are used are customarily made of thin plastic so that their walls are naturally relilient and flexible. The locking of th box cover in closed position is provided by pressing the one or more projections or buttons on one flange into the mating well or wells in the opposing flange. The projections or buttons are undercut at their bases so that they are larger at their outward ends than at their bases. The openings of the mating wells are made slightly narrower than the outer ends of the projections but the other portions of the wells are large enough to accommodate the mating projections. Thus, due to the natural flexibility and resilience of the thin plastic walls of the box, the projections or buttons snap into and are retained in the mating wells when the box cover is swung over onto the box body portion until the flanges are together with the projections or buttons studs alligned with the mating wells and the flanges pressed together to push the projections or buttons into the wells. 
     Boxes of this type are currently used for packaging bakery products such as muffins. The boxes are preferably made of a clear plastic that is rigid but flexible when it is formed into thin walled boxes. Thus the goods in the boxes are clearly visible for sales appeal, are rigid enoungh to protect the contents and are thin walled enough to keep the cost down and to make possible the simple and effective projection and well locking system just described above. 
     The box closing apparatus of this invention is particularly adapted for closing and locking boxes of the foregoing type. Heretofore boxes of this type as used on production lines in commercial bakeries for example have been filled and closed by hand. That is, open boxes moving along on a conveyor belt are filled with muffins or other products by hand at one work station and then closed and locked in closed condition by hand at another work station. Pressing the flanges of these boxes together to snap the projections or buttons into the mating wells is particularly fatiguing and irksome for the workers and is the type of hand work motion that is likely to cause carpal tunnel syndrome. 
     Up to this time there has not been available any suitable or effective machine or apparatus to automate the tedious and potentially damaging work of closing and locking these boxes so that it has had to be done by hand up until now. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is apparatus that eliminates the need to close and lock these boxes by hand. With the apparatus of this invention a box of the above described type is placed on a moving conveyor belt in open condition so that it can be loaded with a product, such as muffins. Then as the box is carried along by the conveyor a guide rail mounted along the path of the conveyor to be at the outside of the cover of the open box swings the cover up and over into closed position in which the flanges on the outer edges of the cover and body of the box are in opposed relation with the projections from one flange in line with the openings of the mating wells in the other flange. Then further movement of the box along the conveyor carries it past a pair of power driven rollers that are mounted edge to edge to rotate about parallel axes that are at right angles to the direction of movement of the conveyor belt. The rollers are rotated in opposite directions and in directions so that their surfaces at their bite move in the same direction and in the direction in which the conveyor belt moves. 
     The rollers are dimensioned and spaced apart for the opposed flanges to pass into the bite of the rollers. The bite is made narrow enough to press the flanges together sufficiently to force the projections on one of the flanges into the wells in the other flange far enough for the projections to snap into and thus be locked in the mating wells. 
     PRIOR ART 
     Guide rails or bars arranged to swing box covers over into closed position as the boxes or cartons are carried along on a convyor belt are well known. For example, see U.S. Pat. No. 3,267,637 to T. R. Baker and U.S. Pat. No. 3,299,615 to M. E. Singer. 
     Also attempts have been made to provide automated apparatus for latching in locked condition press-button snap lock closures. For example, see U.S. Pat. Nos. 3,877,205 and 4,030,272 to Gundersen. These Gundersen patents show fingers or spokes on rotating wheels for pressing projections or buttons into locking relation in mating wells for locking a box cover in closed position on a box. But these systems require that the locking motion of the fingers or spokes by indexed to the movement of the boxes along the conveyor or that some type of trigger mechanism be provided to actuate the movement of the finger or spoke at the precise moment a projection or button and mating well on the box and cover come into operative alignment with the finger or spoke. 
     A particular object and advantage of the apparatus of the present invention is that no special mechanisms are needed to index the movement of the box with the operation of the locking apparatus. The structure of the apparatus of this invention is simple and economical to contruct and to operate. The projections on one flange are pressed into the mating well in the other flange of a box and cover whenever a box is conveyed past the rollers, which do the locking, without regard to the speed of the conveyor or the longitiudinal position of the box on the conveyor. Also the speed of the conveyor which carries the past the rollers may be increased or decreased as desired, to accomodate the loading of goods into the boxes, for example, without having to separately adjust the speed of rotation of the rollers. Moreover, the structure and mode of operation of the roller locking mechanism of this invention is such that no forces are applied during the locking step which could scew a box on the conveyor or cause it to skid or tip which could cause an incomplete closure or perhaps damage the box and necessitate shutting the apparatus down in order to correct the malfunction. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Further objects, advantages and features of the apparatus of this invention will be apparent from the following detailed description of an illustrative embodiment of the invention shown in the accompanying drawings in which: 
     FIG. 1 is a side elevation of a type of box which the apparatus of this invention is adapted to close; 
     FIG. 2 is a top plan view of the box shown in FIG. 1. 
     FIG. 3 is and elarged cross sectional view illustrating the the type of locking arrangement by which the cover of a box of the type shown in FIGS. 1 and 2 is locked in closed position when the cover is closed; 
     FIG. 4 is a top plan view of apparatus in accordance with this invention; 
     FIG. 5 is a view taken along the lines 5--5 of FIG. 4; 
     FIGS. 6a, 6b, 6c and 6d are side elevational views of a box of the type shown in FIGS. 1 and 2 illustrating in sequence the manner is which the cover is moved from an open to a closed position by the apparatus of this invention; 
     FIG. 7 is view taken along the lines 7--7 of FIG. 1; and 
     FIG. 8 is a view taken along the lines 8--8 of FIG. 7. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, the apparatus 10 (shown in FIGS. 4 and 5) of this invention is particularly adapted for closing and locking in closed position a box 20 of the type illustrated in FIGS. 1, 2 and 3. 
     The box 20 shown is a type presently used for bakery goods, such as muffins. It is made of a clear plastic which is thin but stiff. It consists of a bottom portion 21 joined along one edge to a cover portion 22 by a narrow intermediate hinge section 23, in which the thickness of the plastic is made thinner along its center line to form what is know as a `living hinge`, which enables the cover portion to be folded easily over onto the bottom portion to close the box. 
     The bottom and cover portions 21 and 22 of the box each have a flange, 24 and 24, respectively, extending outward from their edges that are opposite the hinged edge. The flange 24 has at least one, and preferably two, rectangular wells 26 in it and the flange 25 has at least one, and preferably two, rectangular projections 22. As indicated in FIG. 3 the wells 26 are shaped and aligned to receive therein in mating relation the projections 27 when the box cover portion 22 is folded over the bottom portion 23. Also, as shown, the outer ends 28 of the projections 28 are wider than their bases and are similarly wider in width than the openings 29 of the wells 26. These widths are made such that when the cover 22 is folded over the bottom 21 and the flanges 24 and 25 are pressed together the projections 27 can be forced into the wells 26 with a little pressure. The plastic of which the box is made is sufficiently rigid and flexible that as the projections 27 are pressed into to wells 26 they can be forced in and when they are part way in, with their relatively larger ends 28 just past the narrowest part of the well openings 29, they snap the rest of the way in and form a dovetail form of interlock, locking the cover 22 in closed position over the bottom 21. 
     Referring now to FIG. 4 and 5, the apparatus 10 has a frame, indicated at 11, with an elongated flat table top 12 on top of the frame. An endless conveyor belt 13 is carried around rolls 14 and 15 which are journalled in the ends of the frame 11 with the upper run of the conveyor belt moving longitudinally over and supported by the table top 12. 
     The conveyor belt 13 is driven by a drive belt 16 around a pulley 17 fixed on the end of roll 15 and around a pulley 18 that is pinned on the drive shaft of a motor 19 which is mounted on the frame 11. 
     A tubular guide bar 30 is mounted on the table top 12 to extend longitudinally over a major portion of the conveyor belt 12. At the left hand end of the table top 12 the left hand end of the guide bar is mounted close to the surface of the conveyor belt by a support mount 31 which consists of a block 32 which is slideable up and down on a verticle post 33 extending up from the table top and held in an adjusted position on the post 33 by a set screw, not shown, A horizontal rod 34 attached to the guide bar 30 is slideably received through the block 32 and held in adjusted position therethrough by a set screw indicated at 35. Similarly the right hand end of the guide bar 30 is mounted above the conveyor belt 13 by a support mount 31a consisting of a block 32a slideable on verticle post 33a through which is carried a horizontal rod 34a which attached to the guide bar 30. The block 32a is held in adjusted position on the post 33a by a set screw, not shown, and the 34 34a, and hence the right hand end of the guide bar 30, is held in adjusted position by a set screw indicated at 35a. Thus the positions of the guide rod 30 up and down and horizontally are adjustable 
     The guide bar 30 is generally sinuous, but its curvature is more accurately described as being the curvature one would generate by grasping the two ends of a circular loop of stiff wire, one in each hand, and pulling them apart to an extent not great enough to straighten the wire and then moving one end up and forward. In any event the guide bar 30 is curved in such a fashion as to fold the cover 22 of a box 20 that is on the conveyor belt up and over onto the bottom 21 of the box as the box is carried from the left end of the conveyor belt to the right end. As illustrated in FIG. 4 the guide bar 30 is positioned so that its left end end is close to the surface of the conveyor belt 13 and under the cover 22 of a box 20 that is on the conveyor belt. Then as the box is carried along on the conveyor, after items such as muffins have been placed in it, the guide bar folds the top 22 up and over onto the bottom 21 of the box as illustrated in FIGS. 6a through 6d. 
     Near the right hand end of the conveyor belt 13, at the side of the conveyor belt, as shown in FIGS. 4 and 5, are mounted a pair of rollers 38 and 39 in vertical, edge to edge relation and spaced slightly apart. In a manner explained more fully below the rollers are driven in opposite directions so that at their bite 38 their surfaces are moving in the same direction, as indicated by the arrows in FIG. 5, which is the direction in which the upper run of the conveyor belt 13 runs, as indicated by the arrow on the conveyor belt 13 shown in FIG. 4. 
     As a box 20 is carried along on the conveyor belt 13 it is held in lateral alignment on the belt by guide rails 39 and 40 which are adjustably mounted on the table top 12 at opposite sides of the conveyor belt 13 by support mounts 31b, 31c and 31d, 31e respectively. These support mounts 31b through 31e are similar in construction and operation to the support mounts 31 and 31a previously described and thus are adapted to adjust the width and lateral position of the path along which a box 20 is carried by the conveyor belt 13. This adjustment, like the adjustment of the position of the guide rod 30, adapts the apparatus for use with different size boxes. 
     As shown in FIG. 4 a box 20 on the left hand end of the conveyor belt 13 is positioned with the side of its bottom portion that is opposite its hinged side against the guide rail 39, whose height is adjusted so that the flange 21 on that side of the box is above the guide rail 39. The guide rail 39 and the guide rail 40 are in adjusted lateral position for the flange 24 of the box bottom 21, and hence also the flange 25 of the box cover 22 when folded over the bottom by the guide rod 30, to pass through the bite 38 of the rollers 36 and 37 as the conveyor belt carries the box to the right hand end of the conveyor belt. 
     The height of the right hand end of the guide bar 30 above the conveyor belt 13 is adjusted so as to bring the cover 22 of the box down toward the bottom 21 just far enough for the projections 27 to be over, but not in, the wells 26 at the point at which the conveyor belt has carried the box up to the bite 38 of the rollers 37, 38. As stated above the rollers 37, 38 are at a height for the flanges 24 and 25 of the box to enter the bite 38 as the conveyor belt carries the box to the right past the rollers 37, 38 and the rollers are spaced apart but are close enough together for them to press the flanges 24 and 25 together sufficiently for the projections 27 to be pushed far enough into the wells 26 for them to snap all the way into the wells, as previously described, thereby locking the box cover 22 in closed position on bottom 21. 
     The rollers 36 and 37 are rotated at the same surface speed as the conveyor belt 13. This assures that the force applied by the rollers to the box flanges 24 and 25 will not skid or scew the box as it passes by the rollers. Additionally this renders it unneccessary to have to index the movement of the box up to and past the locking mechanism, which is provided by the rollers 36 and 37 in this apparatus. 
     Referring now to FIGS. 7 and 8 the surface speed of the rollers 36 and 37 is arranged to be the same as the surface speed of the conveyor. This is provided by power driving the rollers from one of the conveyor rolls, roll 15, by making the rollers 36 and 37 the same diameter as the conveyor roll 15 and by having all the driving pulleys of the drive connection the same diameter. As shown the drive connection is by a drive chain 41 which passes around a pulley 42 fixed on the axle of the conveyor roll 15, around a pulley 43 fixed on the axle of the roller 37, around a pulley 44 fixed on the axle of the roller 36, around an idler roller 45, around an idler roller 46 and back to the pulley 42 on the axle of conveyor roll 15. The rollers 36 and 37 are rotated in opposite directions for their surfaces at the bite 38 between them to be moving in the same direction, indicated by a dashline arrow, by having the drive chain 41 pass in opposite directions around the pulleys 43 and 44 which are fixed on the axles of the rollers 37 and 36, respectively. 
     Still referring to FIGS. 7 and 8, the rollers 36 and 37 are mounted for their height relative to the conveyor belt 13 to be adjusted as desired to accomodate boxes of different sizes. For this purpose the rollers 36 and 37 are journalled on a verticle plate 47 which is carried for slideable up and down movement in a housing 48, which has a suitable opening, indicated at 48a, through its side wall to permit this movement. The plate 47 is moved to an adjusted verticle position by means of a rod 49 extending vertically up from a frame memeber 11a, which forms the bottom of the housing 48, up into an elongated vertical well 50 in the plate near the right hand edge of the plate as viewed in FIG. 7. The lower end portion of the rod 49 is threaded through a threaded sleeve 51 that is fixed in the bottom end of the well 50. The lower end of the rod 50 extends down through a suitable opening through the frame portion 11a with a knurled thumb wheel 52 fixed on the bottom end of the rod. The thumb wheel 52 is captured between the underside of the frame portion 11a and a frame piece 11b which is in the nature of a shelf spaced below and parallel to the frame portion 11a. Thus the rod 49 is prevented from moving vertically when the thumb wheel is turned and the threaded lower portion of the rod 49 turning in the threaded sleeve 51 in the well 50 moves the plate 47, and hence the rollers 36 and 37, up or down, depending on the direction in which the thumb wheel is turned. 
     The upper end of the rod 49 moves through a bearing 53 mounted in the well 50 to support and guide the vertical movement of the plate. At the left hand edge of the plate another vertical rod 54 with its bottom end fixed on the frame portion 11a extends up into an elongated well 55 in the plate through bearings 56 and 57 mounted in the well 55 to hold the plate in alignment as the plate is moved up or down. 
     The idler roll 45 is mounted on the plate 47 and the drive connection by appropriate tension of the drive chain 41 is maintained in different verticle positions of the plate 47 by the other idler roll, idler roll 46, being mounted on an arm 58 that is pivotally mounted on a block 59 on the housing 48. The ider roll 46 is held in pressure contact with the drive chain 41 in all verticle positions of the plate 47 by a coil spring 60 connected between the arm 52 and the housing 48 and biased to urge the arm 58 to pivot upward so as to maintain the tension of the drive chain 41. 
     In operation a box 20 is placed in open condition on the left hand end of the conveyor belt 13 and items, such as muffins, are placed in the bottom 21 of the box. Then as the conveyor belt 13 carries the box along to the right to the rollers 36 and 37 the guide bar 30 swings the box cover 22 up and over onto the box bottom 21. Then as the box is moved past the rollers the flanges 24 and 25 on the box bottom and cover, respectively, pass into and through the bite 38 of the rollers 36 and 37 which press the flange projections 27 into the flange wells 26 far enough to cause the projections to snap the rest of the way into the wells and thus lock the box in closed condition.