US2536384A

US2536384A - Glueless interlock for double walled folding boxes

Info

Publication number: US2536384A
Application number: US21638A
Authority: US
Inventors: Reginald B Meller
Original assignee: Bemiss Jason Corp
Current assignee: Bemiss Jason Corp
Priority date: 1948-04-17
Filing date: 1948-04-17
Publication date: 1951-01-02
Anticipated expiration: 1968-01-02

Description

Jam 2, 1951 R. B. MELLER 2,536,334

GLUELESS INTERLOCK FOR DOUBLE WALLED FOLDING BOXES Filed April 17, 1948 3 Sheets-Sheet l INVENTOR- W QMM ATTORNEY Jan. 2, 1951 R. B. MELLER 2,536,384

GLUELESS INTERLOCK FOR DOUBLE WALLED FOLDING BOXES Filed April 17, 1948 KSheets-Sheet 2 INVENTOR.

M MMAM t; ATTORNIYS W T a RY R B MELLER 2 GLUELESS INTERLOCK FOR DOUBLE WALLED FOLDING BOXES 3 Sheets-Sheet 3 Fig. 8

' A; ATTORNEYi w F m n 1 d '6 mm JF Patented Jan. 2, 1 951 GLUELESS m'rnnnocx ron noma- WALLED rommo noxss Reginald B. Meller, Oakland, Calif., assignor to Demise-Jason Company, San Francisco, Calif., a corporation of California Application April 17, 1948, Serial No. 21,688

21.Claims. (Cl. 229-35) This invention relates to improvements in cartons, boxes, trays, and other structures made from blanks of cardboard, paperboard, or other suitable foldable sheet material, hereinafter collectively referred to as boxes or folding boxes.

The invention is particularly directed to folding boxes which, either partially or entirely, are composed of walls of multiple thickness.

The invention provides a novel interlock for connecting together, without the use of adhesives, staples, or other special securing means, walls of a box in rigid corner forming re ationship where all of the walls, or at least part of them, are of multi-ply thickness. The invention thus extends to boxes requiring heavier than single thickness walls for strength, a form of interlock which, in a somewhat sim ler modification, has found wide adoption throughout the industry for the setting up of boxes having single thickness walls.

According to the invention, two multi-ply walls, or a single ply and a multi-ply wall, meeting at a corner are mechanically interlocked by a peculiar inter-engagement of cut edges formed on or in the stock. The resulting box corner has the strength and rigidity of a glued or stapled construction. The'novel interlock is permanent and cannot, except by the use of special tools, be separated or disengaged and is secure against accidental disengagement by forces acting on the box from the inside or the outside.

The present invention ofiers the advantage of H eliminating gluingor stapling operations in the 1' setting up of a hollow box fro'ma fiat blank, lead-v ing to production rates far in excess of those at- I tainable for glued boxes. The invention further leads to simplification of the mechanical equipment for setting up the boxes .and reduces its cost. Moreover, the invention permits economical setting up of double walled boxes of certain relatively small sizes which heretofore could not be following description taken in connection with the accompanying drawings forming a part of it in which Figure 1 is a plan viewof a flat box blank embodying the invention, the inside surface of the blank facing the observer;

Figure 2 is a fragmentary plan view of a corner portion of the blank shown in Figure 1, in which certain dash dotted lines indicate the relative position which certain elements assume after forming of the blank into hollow box form;

Figure 3 is a plan view of the comer portion of the blank shown in Figure 2 after a gluing and foding operation for forming walls of double thickness;

Figure 4 is a sectional side view of an end wall, a section being taken on line 4-4 of Figure 3:

Figure 5 illustrates an alternative form of construction of the end wall in a view corresponding to that of Figure 4;

Figure 6 is a perspective view of a box set up from the blank shown in Figures 1, 2 and 3;

Figure 7 is a fragmentary plan view of a comer portion of a modified blank, the inside surface of the blank facing the observer;

Figure 8 is a fragmentary plan view of a corner portion of a form of blank for making shallow boxes; and

Figure 9 is a perspective view of a comer portion of a box set up from the blank of Figure 8.

Inthe following description and in the claims, various structural details will be identified by specific names for convenience. The names,

however, are intended to be as generic: in their application'as the art will permit. Corresponding reference characters refer to corresponding parts in the several figures of the drawings.

In the drawingsaccompanying, and forming part'of this specification, certain speciflc'disproduced economically by gluing because of disproportionately high cost due to intricacy of the gluing machines and the relatively low produc-'- tion rates of such machines.

These and various other features, objects and advantages of the invention will appear more fully from a consideration of the detailed description which follows accompanied by drawings showing, for the purpose of illustration, preferred embodiments and applications of the invention.

The invention also consists in certain new and improved details of construction as hereinafter set forth and claimed.

Although the characteristic features of the invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects and advantages, and the manner in which it may be carried out may be better understood by referring to the closure of the invention is made for the purpose Qt -explanation ofbroader aspects of .the invention, but it is understood. that the details may be modified in various respects without departure from the principles of the invention and that the invention may be applied to other structures than the ones shown. I

The blank A shown in Figure 1 issubdivided by several scored'fold lines to provide a bottom panel H to which outer side wall panels i2 and i3 are hinged along side fold lines it and i5. Inner side wall panels l6 and ii are hingedly connected to the outer side wall panels along fold lines l8 and I9, respectively.

Outer end panels 20 and 2i are hingedly connected to the bottom panel H along

end fold lines

22 and 23, respectively, and

inner end panels

24 and 25, slightly narrower than the outer end panels, are hingedly connected to the outer end panels 20 and 2| along fold lines 2. and 21, respectively. Additional folding scores 28, 23, 36 and 3| extend across the-

inner end panels

24 and 25 adjacent the

fold lines

26 and 21. The purpose of these additional folding scores will become apparent hereinafter.

Flaps

32 and 33 are hingedly connected to the outer end panel 20 along

fold lines

34 and 35, respectively. These fold lines are either aligned with, or parallel and slightly offset with respect to, the side fold lines l4 and if to compensate for wall thickness in the succeeding folding op-' erations, asis customary in the art. Flaps 36 and 31 are hingedly connected to the outer end panel 2| along

fold lines

38 and 33 in a similar mann r as described in connection with the

flaps

32 and 33.

Internal cuts 40, 4|, 42 and 43 separate the outer side wall panels l2 and I3 into portions which may be resiliently flexed with respect to each other for the purpose of opening the cuts and inserting portions of the

flaps

32, 33. 36 and 31 into them. The internal cuts 40, 4| 42 and 43 are preferably of bent outline to form

internal tongues

44, 45, 46 and 41 in the panels l2 and I3.

Cut edges are formed on the

flaps

32, 33, 36 and 31 by

external cuts

48, 49, 56 and extending into the body of the flaps from outer edges. The orientation and shape of the

cuts

48, 49, 59 and 5| is such that portions of the cut edges formed by the cuts in the

flaps

32, 33, 35 and 31 upon assembly of the blank into box form move into substantial coincidence with portions of the internal cuts 40, 4|, 42 and 43 so that an edgeto-edge engagement results between. cut edges of the flaps and cut edges of the outer side wall panels, as will hereinafter be apparent.

External tongues

52, 53, 54 and 55 are formed by the

external cuts

48, 49, 56 and 5|, respectively. These external tongues are resiliently defiectable with respect to the remainder of the

flaps

32, 33. 36 and 31 in the same manner as the

internal tongues

44, 45, 46 and 41 may be flexed with regard to the remainder of the outer side wall panels I: and I3.

The

external tongues

53, 54 and 55 include

tab portions

56, 51, 56 and 59 extending partially beyond the confines of the

external tongues

44, 45, 46 and 41 as is particularly apparent from Figure 2 in which the flap 32 is shown in dashdouble-dot-lines superimposed upon the panel |2 in the position which the flap assumes in the set up box. The purpose of these tab portions will become apparent from a consideration of the assembly procedure of the blank which will be described hereinafter.

Internal cuts 66, 6|, 62 and 63 are formed in the inner side wall panels l6 and I1. These internal cuts are preferably of reversely curved outline and form oppositely directed

tongues

64, 65, 66, 61, 68, 69, and 1| in the irmer end wall panels l6 and I1, respectively. The tongues formed by the internal cuts 60, 6|, 62 and 63 are so located and shaped as to make more effective and secure the interlock formed between cut edges of the

external cuts

48, 49, 50 and 5| and edges formed by the internal cuts 40, 4|, 42 and 4 Referring specifically to Figure 2, in which the elements are shown on an enlarged scale, it will be seen that the tongue 64 overlaps the external tongue 52 in the position in which the blank is folded into hollow box form. The overlap causes the flap 64 'to deflect the external tongue 52 with respect to the remainder of the flap 32 into edgeto-edge engaging position with the internal cut 43 as will also become apparent from an inspec- 4 tion of Figure 6 hereinafter described in greater detail.

The oppositely pointed tongue 65 overlies the tab portion 56 of the external tongue 62. This tab portion, as will later become apparent, secures the interlock against accidental disengagement. The tongue 65 which bears down upon the tab portion 56 maintains the tab portion in looking position and protects it against contact with the box contents.

The internal cuts 6|, 62, and 63 and the tongue.- formed thereby are identical in outline and function with the internal cut 60 just described. A detailed description of the

tongues

66, 61, 63, 69, 10 and 1| may therefore be dispensed with.

The assembly of the blank A into hollow box form may proceed as follows:

Adhesive a is first applied to marginal portions of the inner side wall panels l6 and I1 and to marginal portions of the inner

end wall panels

24 and 26 as indicated in Figure l. The panels are then folded about fold lines I8, i9 and 26, 21, respectively, to bring the inner side wall panels and the inner end wall panels face-to-face with the outer side wall panels and the outer end wall panels, respectively, and pressure is applied to the glued portions to produce a secure bond. During the folding the inner

end wall panels

24 and 25 are preferably slightly flexed at the fold lines 28 and 29 to form ridges near the upper edge of the end walls as is apparent from Figure 4.

The resulting blank A, of which a corner portion is shown in Figure 3, has double thickness side walls |2, |6 and double thickness end walls 2|), 24. The blanks A are flat except for the slight ridge at the fold lines 28 and 30. They may be shipped and stored in fiat collapsed condition and are available for immediate setting up into hollow box form at the plant of the user of the boxes.

The setting up of the blanks A into hollow box form may be carried out on manually operated machinery of simple construction, where relatively small volumes are involved, or may be set up on automatic high speed machinery where the volume demand is large.

The setting up of the blank A into hollow box form and the interlocking of the blank at the comers involves the following operations:

The side panels |2, |6 and |3, H are first folded along the side fold lines l4 and I5 to bring the side walls into substantially u right position with respect to the bottom panel H. In this position the stock of the side walls is flexed at the internal cuts in order to open the cuts in the outer wall panels. This may be accomplished by pressing with suitable finger shaped tools against the inner side wall panels as indicated in Figure 6 where a finger 12 is shown as flexing the internal tongue 68 outwardly. Flexing of the internal tongue 68 causes flexing of the internal tongue 46 in the outer side wall panel which overlies it. During the flexing of t e internal tongues the rema nder of the side wall is supported, preferably adjacent the tongues to be flexed so that apertures are formed in the side wall into which the corresponding flaps 32, 33, 36 and 31 may be inserted.

The four internal tongues in the side walls are preferably flexed simultaneously so that all four cuts 40, 4|, 42 and 43 are onened for insertion of portions of the thus 32, 33, 36 and 31 therein The end walls 26. 24 and 2|, 25 are then folded with respect to the bottom panel about the tion of the end walls is then continued while simultaneously the

portions

52, 53, 54 and 55 of the fla s are guided into the opened slits 40,41, 42 and-43. I

This operation brings the edgesof the

external tongues

52,53, 54 .and ,55 into substantial coincidence, with portions of the internal cuts 40, 4|, 42 and 43 as is quite apparent from Figure 2 where the-coincidence of the cut edge 48 with a portion 407 of the cut 40 is shown The position of.the finger shaped tools with respect to the various portions. of the blank during the locking operation is apparentfrorn, Figure 6 where it is seen that th finger shaped tool 12 bears against theside wall It, I 2 with its outer surface-13, opening the cut in the side wall, while permitting the external tongue-14 in the respective flap to move underneath its inner surface 14. After insertion of the

flap portions

52, 53, 54 and 55 underneath the respective finger shaped tools, the tools are drawn or moved towards the inside of the box until the

tab portions

58, 51, 58 and 5,9, which previously-lay on the outside of the outer side wall panels are drawn to the inside of the outer side wall: panels. i I

In this position. the edges of. the. external tongues 52. 53,..54and55 which were in coincidence with edge portionsflof the internal cut 40. 41, 42, and 43 move into edge-toqedge engagement therewith and are maintained in this position by the tab portions on the respective external tongueswhich now lie on between the outer and the inner sidewall panels l2, l and. l3, 11, respectively. Y l

The setup box A" is then removed from the folding mechanism. As shown in Figure 6 the finger shaped tools which opened the cuts in the side walls and which pulled the tab portions from the outside of the outer wall panels to the inside can easily disengage. themselves from the box by movement in the direction of the arrow 75, it being understood that the arrow is used to indicate relative motion since it may be preferred to remove the folded box from its forming mechanism rather, than move the] forming mechanism away from the set upbox. It may therefore be preferred to move the finished box A? in a downward direction in which event, however, the finger 12 moves along the dash dotlines 16. In either case the finger shaped tool is free to disengage itself from the blank by reason of the peculiar shape of the internal cut in the inner side wallpanel which permits the finger to move freely out of the cut 62 atBZ'.

After the box is disengaged from its forming and locking mechanism, the internal tongues 65. S1, 69 and libearagainst'the respective lock tabs whichlie betweenthese tongues and the outer sidewall panels and securely hold these look tabs in place and protect .them from contact with the box contents. v

The set up box is very strong and rigid and its walls resist forces acting on the walls from the outside and from the inside.

Theside edges of the inner

end wall panels

24 and 25 bear. against the side wallpanels l3 and It in edge-to-surface relationship and prevent 6 folding of the side walls towards the inside of the box. The side walls are protected against out ward folding by the

flaps

32, 33, 36 and I! overlyingthe side walls.

The end wall panels 20 and bear against the side edgesof the side walls and prevent inward folding of the end panels. Outfolding of the end panels is prevented by the edge-to-edge en age ment between the

external tongues

52, 53, 54 and 55 and the internal cuts 40, 4|, 42 and 41. This edge-to-edge interlock is very strong and resists a con iderable amount of'force which maybe exerted against the end panels from the inside of the box. Such force subjects the board to compression at the edge-to-ed e engagement and constitutes the most favorable form of load for pa erboard and box board since board ollers relatively great resi tance to compression as compared to tear-resistance which is com aratively low. The compression force exerted against the bo rd at the points of edge-fo-edge' cont ct lies in the plane of the board and the board offers its greatest resistance tndeformation if s bjected to force n this dire tion. external ton ues 52. 53. 54 and 55 throu h the two plies of the side walls furthermore locks the two plies toget er and imparts addit onal rigidity to the s de walls a ainst bul in out if. for exam le, force i exerted aeainst'the upper edges of the side walls at fold lines [8 and I9;

Instead of form ng a r d e in t e surface of the inner end panels as s own in Figure 4. the end panels may be folded along a sin le' fold line 15' as s own in Fi ure 5 to provide suificient abutment al ng ts s de e ges for theside walls ii. i i and l3. H. A re ativ lv w de score may be impressed into the board at 25' to prevent the board from iorrrdne a shar crease so t at the nner end'nanel forms'an inward bulge 24'. as shown in Figure 5. Y The blank B of which a corner portion is shown in Figure com ris s a bottom anel 16 to which side walls and end walls are hineedly connected along fold lines I1 and 18. Theside wall comprises an outer side wall panel I! and an inn'r side wall anel h nged to the outer panel along a fold'line BI. The end wall comprises an outer end panel 82 and an inner end panel 83 hinged to the outer end panel along a fold line 84. A flap 85 is hingedlv' connected to the outer end anel 82 along a fold line 86. An external out 81 extends nto the fla 85 and forms an. external ton ue 88 there n having a tab portion 89. The outer edge of the fiapincludes a portion 90 whosepurpose will presently become apparent.

An internal cut 9| forms an internal tongue 92 in the outer sidewall panel 89. This internal cut comprises a portion 93 adapted to-enter into edge-to-edge engagement with a cut edge formed by the external, cut 81. It further includes a portion 94 forming an edge past'which a tab portion 89 is forced-in assembling the blank into corner forming position. Lastly, theinternal cut comprises a portion 95 adapted to engage the edge portion 90 of the flap 85 tov provide anedge-to-edge interlock effective in a direction opposite with respect to the interlock double interlock efiective in two opposite directions and is not dependent on an engagement between the side edge of the side walls and the surface of the outer end wall panel for preven- The thr ading of the tion of the end walls from folding towards the inside of the box.

The advantage of the interlock shown in Figure 7 is its freedom from play or lost motion. The abutting or interlocking edges may be cut with great accuracy and close tolerances are easier to maintain in cutting interlocking edges than in providing equally close tolerances for the surface-to-edge abutment between the outer end panel and the edge of the side wall.

An internal cut 96 of reverse curvature is formed in the inner side panel it. It forms two internal tongue 81 and st in the panel, the tongue 91 serving to flex the external tongue it into edge-to-edge engagement and the tongue it saving to bear down upon, and protect, the tab portion 88 as hereinbefore described in connection with blank A.

The assembly of the blank B into box form proceeds in the same manner as hereinbefore described in connection with the blank A and the resultant box differs from the box A" of Figure 6 only in that two pairs of edges at each cornerv flap provide an interlock effective in two opposite directions whereby the resulting interlock is completely free from play or lost motion.

The blank C shown in Figure 8 corresponds in most particulars to the blank shown in Figure '1 and primed reference numerals are employed to designate corresponding parts. A detailed description of the blank may therefore be dispensed because of the similarity.

The blank C is particularly designed for shallow boxes. Its interlock corresponds to that of theblank B except for the absence of a cut edge corresponding to edge til on the flap. Correspondinsly. no edge portion corresponding to cut edge 95 is present. The only point of difference between the blanks B and C, except the absence of

edges

90 and 95 is the location ot'the' internal cut 95' which extends to the fold line ll This arrangement permits reduction of the height of a side wall and permits very shallow double walled boxes to be formed economically which heretofore were not economical to make by gluing.

A corner portion of a box set up from the blank ls shown in Figure 9.

The invention thus provides an improved construction for boxes having double side and end walls permitting assembly of the blanks into hollow box forms on relatively simple machinery at high production rates. The boxes embodying the invention are comparable in strength to glued boxes, but are generally superior to glued boxes from a point of economy since complicated box forming and gluing machine may be dispensed with. In its place a relatively simple forming mechanism is used which may be operated at high or slow speeds depending on production requirements. This folding and locking mechanism costs only a fraction of the cost of an ordinary forming and gluing machine and has the added advantage of being operable at the wide range of speeds since no critical glue setting time need be observed.

Boxes embodying the present invention are not only extremely strong but also are relatively tight permitting relatively finely divided material to be packaged. This advantage is attained by providing the cuts in the side wall panels in offset relationship. Comparable tightness is not normally found in gluelessly assembled boxes.

Obviously the present invention is not restricted to the particular embodiments herein shown and described, but may be applied with equal benefit to other forms of boxes. Numerous additions, omissions and substitutions may be made in adapting the invention to specific needs without departure from the spirit and essence of the present invention.

What is claimed is:

1. In a box blank of foldable sheet material including a main panel; a first side wall hingediy connected to the main panel along a first fold line. said first side wall being composed of an outer panel and an inner panel foldable into overlapping face-to-face relationship with the outer panel; a second side wall hingedly eonneeted to the main panel along a second fold line extending at an angle with respect to said first i'old line; and a fiap hingedly connected to said second side wall along a third fold line extending at an angle with respect to said second .fold line, said flap being foldable into face-tofaee overlapping position with respect to the first side wall, the improvement permitting formation. without the use of adhesives. of said panel, walls, and flap into a rigid box corner, the improvement comprising, an internal cut in said outer panel severing the stock of said outer panel to form twopanel portions defiectable with respect to each-other for opening said out; an external cut edge on said flap forming an edge of a defiectable external tongue of said fiapysaid internal cut and said external cut edge being so located with respect to each other that portions of said out and said cutedge are in substantial coincidence when said first and second side wall are in corner forming position permitting an edge portion of the cut edge to engage an edge portion formed by said internal cut when said external tongue is inserted into said opened cut: and an internal cut of bent outline in said inner panel forming an internal tongue in said inner panel adapted to engage the outside surface of said external tongue, thereby maintaining said external tongue in flexed position in which the external tongue engages an edge of the internal cut in the outer panel.

2. A folding box set up from a blank as defined in claim 1.

3. The box blank structure as set forth in claim 1 in which, in addition, the second side wall is composed of an outer panel and an inner panel, the inner panel being foldable against the inside surface of the outer panel in overlapping face-to-face relationship, the inner panel being narrower than the outer panel and furnishing with its side edges an abutment against which the first side wall panel rests when the two side walls are in corner forming position. the abutment preventing folding of the first side wall towards the inside of the corner.

4. A folding box set up from a blank as defined in claim 3.

5. In a box blank of foldable sheet material including a main panel; a first side wall hingedly connected to the main panel-along a first fold line. said first side wall being composed of an outer panel and an inner panel foldable into overlapping face-to-face relationship with the outer panel; a second side wall hingediy connected to the main panel along a second fold line extending at an angle with respect to said first fold line; and a flap hingedly connected to said second. side wall along a third fold line extending at an angle with respect to said second fold line..said fiap being foldable into face-to-face overlapping position with respect to the first side wall, the improvement permitting formation, without the use of adhesives, of said panel, walls, and flap into a. rigid box corner, the improvement comprising, an internal cut of bent outline in said outer panel forming an internal tonguev in said outer panel adapted to be resiliently flexed with respect to the remainder of said outer panel foropening said internal cut; an external cut edge on said flap forming an edge of a defiectable external tongue of said flap, said internal cut.

and said external cut edge being so located with respect to each other th'atportions of said cut and saidcut edge are in substantial coincidence when said first and second side wall are in corner, forming position permitting an edge portion of the cut edge to engage an edge portion formed by said internal cut whensaid external tongue is inserted into said opened cut; and an internal cut of bent outline in said inner panel forming an internal tongue in said inner-panel adapted to engage the outside surface of said external tongue, thereby maintaining said external tongue in flexed position in which the external tongue engages an edge of the internal cut in the outer panel. H r ,7

6. A folding box set up from a blank as defined in claim 5.

, 7. The box blank structure as set forth in claim inwhich, in addition, the second side wall is composed of an outerpanel and an inner panel, thev inner panel being foldable against the inside surface of the outer panel 1H1 overlappingface-,to-face relationship, the inner, panel being narrower than the outer panel and furnishing with its side edges an abutment against which the first side wall panel rests when the two side walls are in corner forming position, the abutment preventing folding of the, first side wall towards the inside of the comer.

8. A folding box set up from a blank as'deflned' in claim 7.

9. In abox blank of foldable sheet material including a main panel; a first side wall hingediy,

connected to tne niain panel along a first ioid line, said first s de wail being composed of an outer panei and an inner panel foldable into overlapping face-to-face relationship with the outer panel; a second, side wall hlngedly; connected to the main panel along a second i'old line, extending at an angle with respect to sa.d first iold line; and a nap hingedly connected to said second side wall along a thlld iold line extending at an angle with respect to said second fold line, said nap be-ng foldable into lace-toface overlapping position with respect to the first side wall, the improvement permitting Iormation,

without the use or adhesives, of said panel, walls,

and nap into a rigid box corner, the improvement comprising, an internal cut of bent outline in said outer panel forming an internal tongue in said outer panel adapted to-be resiliently flexed with respect to the remainder of said outer panel for opernng; said internal cut to permit insertion of saldflap therein in assembling'the blank; an external cut edge on said fiap forming an edge of a deflectable external tongue of said flap, said internal cut and said external cut edge being so located with respect to eachother that portions of said out and sad cut edge are in substantial coincidence when said first and second side wall are in corner forming position permitting an edge portion of the cut edge to engage an edge port;on formed by said internal cut when said external tongue is inserted into said opened cut; and an internal cut of bent outline in said inner panel forming an internaltongue in said inner panel underlying, whensald inner panel is folded against said outer panel, the internal tongue in said outer panel rearwardly of the internal tonguein said outer panel with respect to the adjacent side edge of the inner panel, the internal tongue in said inner panel being adapted to engage the outside surface 01' said external tongue, thereby maintaining said external tongue in, flexed position in which the external tongue engages an edge of the internal cut in the outer panel.

10. A, fold ng boxset up from =aiblank as definedin claim, 9. '1, ll. The box blank structure as set forth in claim -9 in which, in' addition, the second side wall is composed of an outer paneland an inner panel, the inner'panel being foldable against the inside surface of the outer panel in overlap ping face-to -face relationship, the inner panel being narrower than the outer panel and fur nishing with its s deedges an abutment against which the first sidewall panel rests whenthe' two side walls are in. corner forming position, the abutment preventing, folding of the first side wall towards the inside of the corner.. 12. A folding box set up from a blank as definedin claim 11. i i l 13. In a box blank of foldable sheet material including a main panel; a first side wallhingedly connected-to the main panelalongafirst fold line, said first side wall being composed of an outer panel and an inner .panel foldable into overlapping face-to-face relationship with the outer panel; a second side wall hingedly connected to the main panel along a second foldline extending at an angle with respect to said.

first fold line; and a flap hingedly connected to said second sde wall along a third foldline extending at an angle with respect to said second fold line, said flap being foldable into face-toface overlapping position with respect to the first side wall, the improvement permitting formation, without the use of adhesives, of said panel, walls, and flap into a rigid box corner, the im-' edge of a deflectable external tongue of said flap, portions of said internal cut and said external out edge being in substantial coincidence when said first and second side wall are in corner forming position permitting anedge portion of the cut edge to engage an edge portion formed by said internal cut when said external'tongue is'inserted intosaid opened cut, the external tongue being of such outline relatively to'the outline of said external tongue that a tabportionof said external tongue extends beyond the confines of said internal tongue if the first side wall,

the second side wall and the flap are'in corner forming position in which they are to be .inter-' locked; and an internal cut of reversely bent outline in said inner panel forming two oppo-" sitely directed internal tongues insaid inner panel, one of said last named tongues being' adapted to engage the outside surface of said external tongue, thereby maintaining said external tongue 'in flexed position in which the 5 external tongue engages an edge of the internal cut in the outer panel, the other of the last 11 namedtonguesbeingadaptedtobearagainst said tab portion to urge said tab portion against the inner surface of the outer panel after assembly of the corner which assembly includes forcing said tab portion from a position overlying the outside surface of the outer panel to a position overlying the inner surface of the outer panel.

14. A. folding box set up from a blank as defined in claim 13.

15. The box blank structure as set forth in claim 13 in which, in addition, the second side walliscomposedofanouterpanelandaninner panel, the inner panel being foldable against the inside surface of the outer panel in overlapping face-to-face relationship, the inner panel being narrower than the outer panel and furnishing with its side edges an. abutment against which the first side wall panel rests when the two side walls are in corner forming position, the abuts ment preventing folding of the first side wall towards the inside of the corner.

18. A folding box set up from a blank as defined in claim 15.

17. In a box blank of foldable sheet material,

including a main panel; a first side wall hingedly connected to the main panel along a first fold line, said first side wall being compoud of an outer panel and an inner panel foldable into overlapping iace-to-face relationship with the outer panel; a second side wall hingedly connected to the main panel along a second foid line extending at an angle with respect to said first fold line; and a flap hingedly connected to said second side wall along a third fold line extending at an angle with respect to said second fold line, said flap being foldable into face-to-face overlapping position with respect to the first side wall, the improvement permitting formation, without the use of adhesives, of said panel, walls, and flap into a rigid box corner, the improvement comprising, an internal cut of bent outline in said outer panel forming an internal tongue in'said outer panel adapted to be resiliently flexed with respect to the remainder of said outer panel for opening said internal cut; an external cut edge on said fiap forming -an edge of a defiectable external tongue of said fiap, said internal out and said external cut edge being so located with respect to each other that portions of said out and said out edge are in substantial coincidence when saidfirst and second side wall are in corner forming position permitting, when said external tongue is inserted into said opened cut, an edge portion of said out edge to engage an edge portion formed by said internal cut thereby pre-@ 55 venting movement of said tongue in the direction of withdrawal from said opened cut, the external tongue being further so shaped to engage with another edge portion a further edge Portion formed by said internal cut, thereby preventing movement of said tongue in the opposite direction, the external tongue including a tab portion extending beyond the confines of said internal tongue if thefirst side wall, the second side wall and the flap are in corner'forming position in which they are to be interlocked; and an internal cut of reversel'y bent outline in said inner panel forming two oppositely directed internal tongues in said inner panel, one of said last named tongues being adapted to engage the outside surface of said external tongue, thereby maintaining said external tongue in fiexed position in which the external tongue engages an. edge of the internal cut in the outer panel, the other of the last named tongues being adapted to bear against said tab portion to urge said tab P rtion against the inner surface of the outer panel after assembly of the corner which assembly includes forcing said tap portion from a position overlying the inner s rface of the outer panel.

18. A folding bo fined in claim 17.

19. The box blank structure as set forth in claim 17 in which, in addition, the second side wall is composed of an outer panel mid an inner panel, the inner panel being foldable against the inside surface of the outer panel in overlapping face-to-face relationship. the inner panel being narrower than the outer panel and furnishing with its side edges an abutment against which the first side wall panel rests when the two side walls are in corner forming position, the abutment preventing folding of the first side wall towards the inside of the corner.

20. A folding box set up from a blank as d in claim 19.

21. In a folding box made from a blank of foldable sheet material and including. a main panel; side walls hingedly connected to the main panel along side fold lines, each of the side walls being composed of an outer panel and an inner panel lying face-to-face with the outer panel; end walls hingedly connected to the main panel along end fold lines extending transversely with respect to the side fold lines; and fiaps hingedly connected to the end walls and folded into faceto-face overlapping position with respect to the side walls, the improved corner construction comprising, for each corner, an internal cut in said outer panel severing the stock of said outer panel to form two panel portions defiectable with respect to each other for opening said out; an external cut edge on the respective fiap forming an edge of a defiectable external tongue on said fiap, said internal cut and-said external out being in substantial coincidence permitting an edge portion of said out edge to engage an edge portion formed by said internal cut when said external tongue is inserted into said out; an internal cut of bent outline in said inner panel forming an internal tongue in said inner panel adapted to engage the outside surface of said external tongue, thereby maintaining said external tongue in fiexed position in which the external tongue engages an edge of the internal cut in the outer panel; and means associated with said side walls and end walls for locking said side walls against folding from their upright position towards the inside of the box.

REGINALD B. HELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 483,502 Schmidt Sept. 27, 1892 637,838 Vernon Nov. 28, 1899 1,468,696 Bray Sept. 25,1923

2,228,377 Wendt, Jr. Jan. 14, 1941 2,316,362 Poe Apr. 13, 1943 2,366,419 Meller Jan. 2, 1945 2,450,035 De Mian Sept. 28, 1948 FOREIGN PATENTS Number Country Date 398,044 Great Britain Sept. 7, 1933 447,136 Great Britain May 13. 1936 set up from a blank as de-