Corner structure and blank for a tray or tray cover

Corner structure for an open tray or tray cover is formed from a unitary blank comprising a rectangular main panel, a first pair of outer side panels foldably joined to a first pair of opposite side edges of the main panel, a first pair of inner side panels foldably joined respectively to the edges of the first pair of outer side panels which are remote from the main panel, a first pair of base flaps foldably joined respectively to the edges of the first pair of inner side panels which are remote from the first pair of outer side panels, a second pair of outer side panels foldably joined respectively to a second pair of opposite side edges of the main panel, a pair of inner side panels foldably joined respectively to the edges of the second pair of outer side panels which are remote from the main panel, a second pair of base flaps foldably joined respectively to the edges of the second pair of inner side panels which are remote from the second pair of outer side panels, a collapsible web at each corner of the main panel and foldably joined to the adjacent end of each one of the first and second pairs of outer side panels, the outer corners of the first pair of inner side panels being configured to define trapezoidal cutaway areas, and a locking tab of trapezoidal configuration adjoined to each end of each base flap.

TECHNICAL FIELD 
This invention relates to containers such as are formed of paperboard and 
which may include a box like tray and a box like cover arranged to 
cooperate and close the tray. 
BACKGROUND ART 
U.S. Pat. No. 622,274 issued Apr. 4, 1899 for a paper box discloses double 
thickness side and end walls together with base flaps foldably joined to 
the inner panel of each side and end wall and which is disposed in flat 
face contacting relation with the bottom panel of the box. Such structure 
constitutes reinforcement for the side and end edges of the box. 
U.S. Pat. No. 2,769,588 issued Nov. 6, 1956 discloses a box having bottom, 
side and end walls formed from a unitary blank and wherein suitable 
locking tab structure is provided for adjoining the corners of the side 
and end walls together with adhesive applied to certain areas of the blank 
to form a completed box. 
Another structure is known and sometimes referred to as a "BEERS" box. This 
type of structure is used at retail outlets for packaging items such as 
folded shirts and the like. The "BEERS" box requires glue at its corners 
and is not characterized by a neat appearance wherein the corners are 
formed of side and end walls which are disposed at right angles to each 
other and is not mechanically strong. The "BEERS" box has the advantage 
that it can be shipped from the box manufacturer to the retailer and 
stored in flat collapsed form and thus does not require a substantial 
amount of space. This device is also simple to set-up. 
Attractive sturdy rigid boxes which have square corners are not popular for 
certain purposes at retail outlets because they do not come in collapsed 
condition to the retailer and hence require a substantial amount of 
storage space. Such boxes have glued corners and are expensive. 
SUMMARY OF THE INVENTION 
According to this invention in one form, a box or tray having squared 
corners is shipped by the manufacturer in blank collapsed form to the 
retailer and is set up by the retailer without the use of glue. 
A tray or tray cover formed according to one form of this invention is 
formed from a unitary blank and comprises a quadrilateral main panel 
having right angle corners, four side walls each of which includes an 
outer side panel foldably joined to an edge of the main panel, an inner 
side panel foldably joined to the edge of the outer side panel which is 
opposite from the main panel, a base flap foldably joined to the edge of 
the associated inner side panel remote from the fold line between the 
associated outer side panel and the associated inner side panel, the inner 
side panel being in close face contacting relation with the inner surface 
of the associated side panel and each base flap being in flat face 
contacting relation with the main panel, a locking tab having a locking 
edge and foldably joined to each end of the base flaps which are 
associated with one pair of opposite sides of the box together with a 
cutaway section formed in the outer corners of each inner side wall 
associated with the other pair of opposite sides of the tray or cover, the 
structure being held in setup condition by engagement of the locking edge 
of each locking tab with an edge of the adjacent cutaway area, and a 
collapsible web structure at each corner of the main panel foldably 
adjoined to the adjacent end edges of the outer side walls which intersect 
at each corner of the main panel.

BEST MODE OF CARRYING OUT THE INVENTION 
With reference primarily to FIG. 1, the numeral 1 designates the main 
quadrilateral panel of the blank having right angle corners. Outer side 
panel 2 is foldably joined to main panel 1 along fold line 3 while outer 
side panel 4 is foldably joined to main panel 1 along fold line 5. Outer 
side panel 6 is foldably joined to main panel 1 along a fold line 7 and 
outer side panel 8 is foldably jointed to main panel 1 along fold line 9. 
The outer side panels are interconnected by web structures 10, 11, 12 and 
13 which are disposed at the four corners of main panel 1. Each web 
structure is collapsible along a fold line such as indicated at 14, 15, 16 
and 17. Web 10 is foldably joined to outer side panel 2 along fold line 18 
and to the adjacent end of outer side panel 6 along fold line 19. Web 11 
is foldably joined to outer side panel 2 along fold line 20 and to outer 
side panel 8 along fold line 21 while web 13 is foldably joined along fold 
line 22 to the end of outer side panel 8 and along fold line 23 to the end 
of outer side panel 4. Web 12 is foldably joined to outer side panel 6 
along fold line 24 and to outer side panel 4 along fold line 25. 
Outer side panels 2, 4, 6 and 8 are reinforced. For example, inner side 
panel 26 is foldably joined to outer side panel 2 along a fold line 27 
while inner side panel 28 is foldably joined to outer side panel 4 along 
fold line 29. In like fashion, inner side panel 30 is foldably joined to 
outer side panel 6, a long fold line 31 and inner side panel 32 is 
foldably joined to outer side panel 8 long fold line 33. 
When the tray is assembled, inner side panels 26, 28, 30 and 32 are 
disposed in flat face contacting relation with the outer side panels 2, 4, 
6 and 8 respectively. 
Base panel 34 is foldably joined to inner side panel 26 along fold line 35 
while base panel 36 is foldably joined to inner panel 28 along fold line 
37. Base panel 38 is foldably joined to inner side panel 30 along fold 
line 39 and base panel 40 is foldably joined to inner side pane 32 along 
fold line 41. Base panels 34, 36, 38 and 40 are disposed in flat face 
contacting relation with main panel 1 when the tray is set up. 
For locking the elements in set up condition, locking tab 42 is foldably 
joined along fold line 43 to one end of base panel 38 and a similar 
locking tab 44 is foldably joined to the opposite end of base panel 38 
along fold line 45. The edge 50 of locking tab 42 is spaced from the outer 
edge of base panel 38. At the other end of the blank, locking tab 46 is 
foldably joined to base panel 40 along fold line 47 and locking tab 48 is 
foldably joined to base panel 40 along fold line 49. All of the locking 
tabs are of identical construction. It is obvious from an inspection of 
these tabs that they are of trapezoidal configuration. As is clear from 
FIG. 4, tab 42, for example, is defined by its fold line 43, its short 
parallel edge 50 and its longer parallel edge 51 together with the 
angularly disposed edge 52. Edges 50, 51 and 52 are exposed and free of 
attachment to any other element. 
For cooperating with the locking tabs, each end of each inner side panel 26 
and 28 is cutaway at its outer corners to define a cutaway area partially 
indicated by edges of the cutout section. For example the short parallel 
edge 50 of locking tab 42 engages the short transverse edge or cut line 
50a of the cutout corner portion of inner side panel 28. Edge 38a of panel 
38 engages inner panel 28 adjacent fold line 37 and holds the inner side 
panel 28 in a normal position relative to main panel 1 and prevents 
collapse of the inner side panel 28. In like fashion, the cut edge 52a of 
cutaway area 53 abuts and coincides with the edge 52 of the locking tab 
42. All of the locking tabs are configured in a manner identical to 
locking tab 42 and cooperation of locking tabs 44, 46 and 48 with 
associated cutaway areas 54, 56 and 55 is identical to that of locking tab 
42 and its cutaway area 53. 
Extending tabs 56 and 57 are formed at the outer corners of base flap 34 
while identical extending tabs 58 and 59 are formed at the outer corners 
of base flap 36. 
The cutaway end portions of the base panels 34 and 36 which are designated 
by the arrows 34a and 36a serve to facilitate locking and holding action 
of locking tabs 44, 48, 42 and 46. For example and with reference to 
locking tab 42, cutaway area 36a affords space into which the lower edge 
43 of locking tab 42 is pressed. The memory or "flight" along fold line 43 
causes tab 42 to press against the inner surface of outer side panel 4 and 
also causes edge 52 to engage securely the edge 52a while locking tab 42 
snaps into secure locking position without overlapping edge 52a. 
In order to set up the carton so that each corner appears from the inside 
as shown in FIG. 2, the inner side panel 28 is folded inwardly along fold 
line 29 and the outer side panel 5 together with associated structure is 
folded along the fold line 5 into vertical position so as to cause the 
base flap 36 to lie in flat face contacting relation against the main 
panel 1. After panel 28 is in vertical position, inner side panel 30 is 
folded along fold line 31 into flat face contacting relation with the 
outer side panel 6 and outer side panel 6 is folded into perpendicular 
relation to main panel 1 which folding operation causes the base flap 38 
to fall into flat face contacting relation with the main panel 1. During 
these folding operations, the web 12 collapses on fold line 16 and is 
captured between the adjacent ends of outer side panel 6 and inner side 
panel 30. During this folding operation, the locking tab 42 swings along 
its fold line 43 into a perpendicular position relative to main panel 1 
and the locking edge 52 of locking tab 42 comes into abutting engagement 
with the edge 52a of cutaway area 53 and the set up corner appears as 
shown from inside in FIG. 2. 
FIG. 3 shows the folding of inner side panel 28 and of base flap 36 after 
completion of their folding operation and shows outer side panel 6, inner 
side panel 30 and base flap 38 during an intermediate stage of folding 
from the flat position represented in FIG. 1 to the set up condition shown 
in FIG. 2. 
It is obvious that a tray or tray cover may be formed according to the 
invention. Minor changes in dimensions would be made to accommodate proper 
interfitting of the two components as is obvious. 
From the foregoing discussion taken in conjunction with the drawing, it is 
clear that by the invention a sturdy attractive tray or tray cover is 
provided which requires no glue and which therefore is suitable for use at 
the retail level to package various items sold to the public and for use 
in many industrial applications.