Folding container

A folding container includes a lock member L disposed on each of side walls 3 brought down first, the lock member L including a pair of lock bars Lb movable in a horizontal direction and one operation portion La, an inclined spring member 12 provided in the operation portion and including a tip portion placed in a spring receiving and supporting block 3n formed on each of the side walls brought down first, a cam hole portion 21a formed in each of the lock bars and into which a driven short shaft 15 formed on the operation portion is inserted, and a spring member 22 formed on each of the lock bars and configured to come into abutting contact with a spring member abutting block 3x formed on each of the side walls brought down first, so that when the lock bars are moved in a direction in which the lock bars approach each other, the operation portion is prevented from being moved by movement of the lock bars in the direction in which the lock bars approach each other.

FIELD OF THE INVENTION

The present invention relates to a folding container in which side walls disposed so as to surround a bottom portion can be folded so as to overlap the bottom portion.

BACKGROUND OF THE INVENTION

A folding container is conventionally known which includes long side walls coupled, via hinge members, to respective opposite long side portions of a bottom portion formed so as to have a substantially rectangular planar shape, and short side walls also coupled, via hinge members, to respective opposite short side portions of the bottom portion. The folding container is assembled into box form by raising the long side walls and the short side walls substantially perpendicularly to the bottom portion. Furthermore, when the folding container is folded, the long side walls and the short side walls are folded so as to overlap the bottom portion. When the folding container is in assembled box form, the long side walls or the short side walls are locked by lock members so as not to fall down toward the bottom portion.

For example, U.S. Pat. No. 6,290,081 discloses a lock member disposed on a short side wall and including one operation portion movable along the wall surface of the short side wall, paired lock bars movable in a horizontal direction, and a vertical motion-horizontal motion conversion mechanism composed of inclined cam grooves formed in the respective lock bars and a driven short shaft projected from the operation portion, the vertical motion-horizontal motion conversion mechanism converting vertical motion of the operation portion into horizontal motion of the lock bars.

If the operation portion is located at a lower position, the tip portion of each of the lock bars is inserted into a fitting recess portion formed in the corresponding long side wall. Thus, each of the short side walls is locked on the long side walls via the lock members so as not to fall down toward the bottom portion. Furthermore, the operation portion located at the lower position is moved upward along the wall surface of the short side wall to move the paired lock bars closer to each other in the horizontal direction. This allows the tip portions of the lock bars to be discharged from the fitting recess portions formed in the respective long side walls. Consequently, the lock state is cancelled in which the short side walls are locked on the long side walls via the lock members. Therefore, the short side walls can be brought down so as to overlap the bottom portion.

According to the above-described conventional folding container, to fold the folding container assembled in box form, an operator moves the operation portion upward. However, depending on the position of the operator's hand with respect to the operation portion, the operation portion fails to maintain a horizontal state but is inclined while being moved upward. If the operation portion is inclined while being moved upward, the operation portion hinders smooth horizontal movement of the paired lock bars coupled together via the vertical motion-horizontal motion conversion mechanisms. This may disadvantageously prevent the reliable cancelation of the lock state in which the long side walls are locked on the short side walls via the vertical motion-horizontal motion conversion mechanisms.

Furthermore, a handling through-hole into which the operator's hand is inserted in order to carry the folding container assembled in box form is located close to an operation portion operating recess portion into which the operator places the hand in order to move the operation portion of the lock member upward or downward. Thus, when carrying the folding container assembled in box form, the operator may inadvertently place the hand in the operation portion operating recess portion to move the operation portion upward to cancel the lock state of the short side walls and the long side walls.

Moreover, the paired lock bars are horizontally moved via the vertical motion-horizontal motion conversion mechanism. Hence, a strong force is required to move the lock bars in the horizontal direction. This may disadvantageously prevent operations of folding and assembling the folding container from being properly performed.

Furthermore, when the folding container is in assembled box form, the operation portion, and a leaf spring and the vertical motion-horizontal motion conversion mechanism which are included in the operation portion are arranged in the operation portion operating recess portion that is open to the outside of the short side wall. Thus, an external member may be inadvertently placed in the operation portion operating recess portion, thus damaging the operation portion and the leaf spring and vertical motion-horizontal motion conversion mechanism which are included in the operation portion.

An object of the present invention is to solve the above-described problems with the conventional folding container.

SUMMARY OF THE INVENTION

To accomplish the above-described object, the present invention provides a folding container including a first pair of opposite side walls brought down first toward a bottom portion and a second pair of opposite side walls brought down toward the bottom portion after the first pair of opposite side walls has been brought down, wherein first, the folding container comprises a lock member disposed on each of the side walls brought down first, the lock member comprising a pair of lock bars movable in a horizontal direction and one operation portion, an inclined spring member provided in the operation portion and including a tip portion placed in a spring receiving and supporting block formed on each of the side walls brought down first, a cam hole portion formed in each of the lock bars and into which a driven short shaft formed on the operation portion is inserted, and a spring member formed on each of the lock bars and configured to come into abutting contact with a spring member abutting block formed on each of the side walls brought down first, so that when the lock bars are moved in a direction in which the lock bars approach each other, the operation portion is prevented from being moved by movement of the lock bars in the direction in which the lock bars approach each other, wherein second, when the operation portion included in the lock member is pivotally moved inward downward in the folding container using, as a pivotal movement supporting point, a pivotal short shaft formed on the operation portion and fitted in a fitting recess portion of a pivotal short-shaft supporting block formed on each of the side walls brought down first, a lock state in which the side walls brought down first are locked on the side walls brought down second is cancelled, and wherein third, a central space portion formed in each of the side walls brought down first is covered by a cover member.

The folding container includes the first pair of opposite side walls brought down first toward the bottom portion and the second pair of opposite side walls brought down toward the bottom portion after the first pair of opposite side walls has been brought down, and comprises the lock member disposed on each of the side walls brought down first, the lock member comprising the pair of lock bars movable in the horizontal direction and the one operation portion, the inclined spring member provided in the operation portion and including the tip portion placed in the spring receiving and supporting block formed on each of the side walls brought down first, the cam hole portion formed in each of the lock bars and into which the driven short shaft formed on the operation portion is inserted, and the spring member formed on each of the lock bars and configured to come into abutting contact with a spring member abutting block formed on each of the side walls brought down first, so that when the lock bars are moved in the direction in which the lock bars approach each other, the operation portion is prevented from being moved by movement of the lock bars in the direction in which the lock bars approach each other. Thus, each of the lock bars simply elastically deforms the spring member formed on the lock bar. This reduces a load imposed on the pair of lock bars when the lock bars are horizontally moved in the direction in which the lock bars approach each other. Thus, an operation of assembling the folding container is facilitated.

Furthermore, when the operation portion included in the lock member is pivotally moved inward downward in the folding container using, as a pivotal movement supporting point, the pivotal short shaft formed on the operation portion and fitted in the fitting recess portion of the pivotal short-shaft supporting block formed on each of the side walls brought down first, the lock state in which the side walls brought down first are locked on the side walls brought down second is cancelled. Thus, regardless of where on the top surface of the operation portion formed on an operation main body included in the operation portion, an operator's finger is located, the laterally paired lock bars, disposed across the operation portion, have the same horizontal travel distance. This enables reliable cancellation of the lock state in which the first pair of opposite side walls are locked, via the lock members, on the second pair of opposite side walls brought down toward the bottom portion after the first pair of opposite side walls has been brought down.

Moreover, the central space portion formed in each of the side walls brought down first is covered by the cover member. Thus, the operation portion and lock bars included in the lock member located in the central space portion are prevented from being exposed to the outside of each of the side walls brought down first. Therefore, the operation portion and lock bars included in the lock member located in the central space portion can be prevented from being damaged by an external member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described below. However, the present invention is not limited to the present embodiment unless the spirits of the present invention are departed from.

As shown inFIG. 1, a folding container according to the present invention includes a bottom portion1, long side walls2hinged to respective opposite long side embankment portions1aof the bottom portion1, and short side walls3hinged to respective opposite short side embankment portions1bof the bottom portion1. In the present embodiment, each of the long side embankment portions1ais formed to be higher than each of the short side embankment portions1b.

As is well known, the folding container assembled in box form as shown inFIG. 1can be folded into a low compact form as follows. First, the short side walls3are brought down so as to overlap the bottom portion1. Then, the long side walls2are then brought down so as to overlap the short side walls3laid on top of the bottom portion1. The folding container folded as described above can be assembled into box form as shown inFIG. 1, as follows. First, the long side walls2are raised vertically. Then, the short side walls3are raised vertically.

Now, the long side wall2will be described with reference toFIGS. 1 to 3.

The long side wall2includes a substantially square plate-like portion2a. An upper-end horizontal flange2bis formed at the upper end of the long side wall2. Furthermore, vertically long, long side wall-side engaging members2care formed at respective opposite vertical ends of the long side wall2; each of the long side wall-side engaging members2cis substantially perpendicular to the plate-like portion2aand is also perpendicular to the inner surface (the surface positioned, when the folding container is folded into box form, inside the folding container assembled in box form)2a1of the plate-like portion2a. At an upper end of a corner formed by a vertical, vertically long band-like plate (hereinafter referred to as an end vertically-long band-like plate)2c1and the inner surface2a1of the plate-like portion2a, an engaging recess portion2dis formed. The engaging recess portion2dis surrounded by the end vertically-long band-like plate2c1, a vertical side wall2d1parallel to the end vertically-long band-like plate2c1, a top plate2d2configured to couple the upper end of the vertical side wall2d1and the end vertically-log band-like plate2c1together, a bottom plate2d3configured to couple the lower end of the vertical side wall2d1and the end vertically-log band-like plate2c1together, and the plate-like portion2a. Furthermore, an upper-end fitting hole2e1is formed at the upper end of the above-described end vertically-long band-like plate2c1. An appropriate number of fitting holes2e2are formed in the end vertically-long band-like plate2c1, positioned below the upper-end fitting hole2e1. In the illustrated example in the present embodiment, two fitting holes2e2are formed.

Now, the short side wall3will be described with reference toFIGS. 1 and 4to7.

The short side wall3includes a substantially square plate-like portion3a, and an upper-end horizontal flange3bformed at the upper end of the short side wall3. Furthermore, vertically long, end vertical ribs3care formed at respective opposite vertical ends of the short side wall3; each of the end vertical ribs3cextends perpendicularly to the plate-like portion3atoward the outer surface (the surface positioned, when the folding container is folded into box form, outside the folding container assembled in box form)3a1of the plate-like portion3a.

Outside the end vertical ribs3c, a vertically long, short side wall-side engaging member3dis extended along the plate-like portion3a. Upper-end fitting projecting portions3e1perpendicular to the plate-like portion3ais formed at the upper end of the short side wall-side engaging member3d. Furthermore, an appropriate number of fitting projecting portions3e2are formed under the upper-end fitting projecting portion3e2. In the illustrated example in the present embodiment, two fitting hole fitting projecting portions3e2are formed.

As shown inFIG. 1, when the folding container is folded into box form, the upper-end fitting projecting portion3e1formed at the upper end of the short side wall-side engaging member3dof the long side wall3is fitted into the upper-end fitting hole2e1formed at the upper end of the long side wall-side engaging member2cof the long side wall2. Furthermore, the fitting projecting portion3e2formed on the short side wall-side engaging member3dof the short side wall3is fitted into the fitting hole2e2formed in the long side wall-side engaging member2cof the long side wall2.

An upper horizontal rib3fis formed at the top of the outer surface3a1of the plate-like portion3aforming the short side wall3and at a predetermined distance from the upper-end horizontal flange3b. The upper horizontal rib3fextends to the end vertical rib3c. The upper-end horizontal flange3band the upper-end horizontal rib3fare coupled together by an upper-end vertical portion3c2extending vertically via an upper horizontal portion3c1of the end vertical rib3c. Furthermore, opposite, paired closer-to-center coupling vertical ribs3gare formed at a predetermined distance from each other so as to couple a central area of the upper-end horizontal flange3band a central area of the upper horizontal rib3ftogether. Closer-to-end coupling vertical ribs3hare formed closer to the respective end vertical ribs3cthan the respective closer-to-center coupling vertical rib3gand at a predetermined distance from each other. Moreover, a vertically long coupling block3iconfigured to couple the closer-to-center coupling vertical rib3gand the closer-to-end coupling vertical rib3htogether is formed in the gap between the closer-to-center coupling vertical rib3gand the closer-to-end coupling vertical rib3h. The closer-to-end coupling vertical rib3hand the vertically long coupling block3imay be appropriately omitted. A coupling vertical rib configured to couple the upper-end horizontal flange3band the upper horizontal rib3ftogether may additionally be provided between the upper-end vertical portion3c2of the end vertical rib3cand the closer-to-center coupling vertical rib3g.

A central space portion A1covered by a cover member4described below is formed by the upper-end horizontal flange3b, the upper horizontal rib3f, the opposite, paired closer-to-center coupling vertical rib3g, and the outer surface3a1of the plate-like portion3a, all of which are described above.

A lock bar insertion hole through which a lock bar described below can be inserted is drilled in each of the vertical end wall3d1included in the short side wall-side engaging member3d, the upper-end vertical portion3c2of the end vertical rib3c, the closer-to-end coupling vertical rib3h, the vertically long coupling block3i, and the closer-to-center coupling vertical rig3g, all of which are described above; the lock bar insertion holes in the above-described components appear to communicate with one another as viewed from the vertical end wall3d1of the short side wall-side engaging member3d. The lock bar insertion holes include a lock bar insertion hole3d1′ drilled in the vertical end wall3d1of the short side wall-side engaging member3d, a lock bar insertion hole3c2′ drilled in the upper-end vertical portion3c2of the end vertical rib3c, a lock bar insertion hole3h′ drilled in the closer-to-end coupling vertical rib3h, a lock bar insertion hole (not shown in the drawings) drilled in the vertically long coupling block3i, and a lock bar insertion hole3g′ drilled in the closer-to-center coupling vertical rig3g.

Paired pivotal short-shaft supporting blocks3jare formed on a part of the plate-like portion3apositioned in the central space A1and close to the upper-end horizontal flange3b, and the paired pivotal short-shaft supporting blocks3jextend perpendicularly to the outer surface3a1of the plate-like portion3a. A fitting recess portion3j1is formed in the pivotal short-shaft supporting block3j.3kis a vertical reinforcing rib formed on the plate-like portion3aso as to couple the pivotal short-shaft supporting block3jand the upper horizontal rib3ftogether.

Paired spring receiving and supporting vertical rib3mis formed on the plate-like portion3apositioned closer to the center of the pivotal short-shaft supporting block3jso as to couple the upper-end horizontal flange3band the upper horizontal rib3ftogether. A spring receiving and supporting block3nis formed on the lower portion of a corner formed by each of the opposite side surfaces3m1of the paired spring receiving and supporting vertical rib3mand the outer surface3a1of the plate-like portion3a. Furthermore, the tip of the spring receiving and supporting block3nis formed to project from the tip of the spring receiving and supporting vertical rib3m. The top surface3n1of the spring receiving and supporting block3nis formed by a horizontal surface3n1′ extending from the outer surface3a1of the plate-like portion3aand an inclined surface3n1″ extending upward from the end of the horizontal surface3n1′.

A pedestal3pis formed on a corner formed by the outer surface3a1of the plate-like portion3aand a part of the top surface of the upper horizontal rib3fwhich is positioned in the central portion between the opposite, paired spring receiving and supporting vertical rib3m. Paired reinforcing vertical pieces3qare provided upright on a corner formed by the top surface of the pedestal3pand the outer surface3a1of the plate-like portion3a.

A recess portion3rwith a circular-arc planar shape is formed in a central portion of the upper-end horizontal flange3b; the recess portion3rextends from the inner surface (the surface positioned, when the folding container is folded into box form, inside the folding container assembled in box form)3a2of the plate-like portion3atoward the outer surface3a1of the plate-like portion3a. A horizontally long, rectangular through hole3sconfigured to communicate with the circular-arc recess portion3ris formed in a part of the plate-like portion3aat which the circular-arc recess portion3ris positioned. An operation portion insertion space portion A2is formed, by the circular-arc recess portion3rand the rectangular through-hole3s, in a central portion of the inner upper corner of each of the short side walls3of the folding container assembled in box form.

A cutout through-hole3tis formed close to each of the opposite ends of a corner formed by the upper-end horizontal flange3band the plate-like portion3a. Furthermore, an appropriate number of locking through-holes3uare formed in a part of the upper horizontal rib3fwhich is positioned in the central space portion A1. In the illustrated example in the present embodiment, four cutout through-holes3uare formed. Moreover, an elastically deformable, elastic locking piece3vextending perpendicularly to the upper-end horizontal flange3bis suspended from a part of the bottom surface of the upper-end horizontal flange3bwhich is positioned in a central portion of the rectangular through-hole3sformed in the plate-like portion3aand forming the above-described operation portion insertion space portion A2. A lock bar bottom surface supporting block3wconfigured to guide and support the bottom surface of the lock bar described below is formed on a corner formed by the top surface of the upper horizontal rib3fand the vertical reinforcing rib3kformed so as to couple the pivotal short-shaft supporting block3jand the upper horizontal rib3ftogether.

Furthermore, a spring member abutting block3xis formed on a corner formed closer to the short side wall-side engaging member3dby the spring receiving and supporting vertical rib3mand the upper horizontal rib3fso that the tip portion of a spring member formed on the lock bar included in the lock member described below can come into abutting contact with the spring member abutting block3x.

Now, a lock member L including one operation portion La and paired lock bars Lb will be described with reference toFIGS. 8 to 10.

The operation portion La includes a horizontally long, substantially prismatic operation main body10, and two horizontal arms11formed on respective opposite vertical side surfaces10aof the operation main body10. Furthermore, a pivotal short shaft11bis formed on a leading vertical surface11aof each of the horizontal arms11. Moreover, inclined spring members12formed as paired band-like plate members are formed are formed in a central portion of a lower horizontal plate portion10bincluded in the operation main body10so as to extend away from each other and along the longitudinal direction of the operation main body10. Additionally, an inclined spring protect piece13is formed perpendicularly to the lower horizontal plate portion10bof the operation main body10, on a part of the lower horizontal plate portion10bof the operation main body10which is positioned in a central portion of a root portion12aof the paired inclined spring members12. A vertical distance from the bottom surface of the lower horizontal plate portion10bto the lower end13aof the inclined spring member protect piece13is substantially the same as that from the bottom surface of the lower horizontal plate portion10bto the tip portion12bof the inclined spring member12. In other words, the lower end13aof the inclined spring member protect piece13and the tip portion12bof the inclined spring member12are positioned on substantially the same horizontal surface. In this configuration, the operation portion La corresponding to a part accommodated in the box comes into abutting contact with the side wall or the like of the box. Even if the paired inclined spring members12act to tilt excessively, the inclined spring member protect piece13can come into abutting contact with the side wall or the like of the box to prevent the inclined spring members12from being excessively deformed. The inclined spring members12can thus be prevented from being damaged. The inclined spring member protect piece13may be omitted.

14is a circular-arc operation portion. The top surface14aof the operation portion14is formed so as to incline upward with respect to the top surface of the upper horizontal plate portion10cincluded in the operation main body10. Furthermore, a circular arc portion14bof the operation portion14is positioned on the operation main body10side. A linear portion14cof the operation portion14is positioned away from the operation main body10. Furthermore, on a side surface portion11cof each the paired horizontal arms11which is positioned on the linear portion14cside of the operation portion14, a driven short shaft15is projected so as to extend in a substantially vertical direction from the side surface portion11c.

Now, the lock bar Lb will be described with reference toFIGS. 8,11, and12.

The lock bar Lb includes a vertical plate-like member20and a substantially square cam plate21provided upright close to one end of the top surface20aof the plate-like member20. A substantially triangular cam hole portion21ais drilled in the cam plate21. Furthermore, an inclined surface20bis formed at a tip portion of the plate-like portion20which is positioned opposite the cam plate21. The cam hole portion21ais formed of a top surface21a1formed to extend in a substantially horizontal direction, a side wall surface21a2positioned on the plate-like member20side, and an inclined surface21a3configured to couple the lower end of the side wall surface21a2to an end of the top surface21a1which is located farther from the side wall surface21a2.

The vertical tip portion21bof the cam plate21is configured to project from the vertical tip portion20cof the plate-like member20which is positioned opposite the inclined surface20b. Furthermore, a vertical spring member22formed as a band-like plate member extending downward in a substantially vertical direction is formed at the vertical tip portion21bof the cam plate21. Such a recess portion20das does not hinder horizontal movement of the lock bar Lb is formed in a part of one side surface of the plate-like member20which is positioned close to the cam plate21so that the above-described vertical reinforcing rib3kformed to couple the pivotal short-shaft supporting block3jand upper horizontal rib3ftogether can be inserted into the recess portion20d.

Now, the cover member4will be described with reference toFIGS. 13 and 14.

The cover member4includes a main body portion4aformed like a horizontally long plate-like member and an upper-end block portion4bextending perpendicularly to the main body portion4afrom the upper end of the main body portion4a. Insertion pieces4care each provided upright at the tip portion of the top surface4b1of the upper-end block portion4bso as to be inserted into the corresponding cutout through-hole3tformed close to each of the opposite ends of a corner formed by the upper-end horizontal flange3band plate-like portion3aof the short side wall3. Furthermore, a triangular-prismatic vertical projecting portion4dis formed at the lower end of each of the opposite vertical side surfaces4a1of the main body portion4aso that the vertical projecting portion4dcan be hooked on an inner edge3g1positioned closer to the lock bar insertion hole3g′ formed in the closer-to-center coupling vertical rib3g. The triangular-prismatic vertical projecting portion4dincludes a vertical side surface4d1extending perpendicularly to the vertical side surface4a1of the main body portion4a, and a vertical inclined surface4d2inclined from the vertical tip of the vertical side surface4d1toward the vertical side surface4a1of the main body portion4a. The vertical inclined surface4d2is configured to lie closer to the upper-end block portion4b.

Furthermore, triangular-prismatic horizontal projecting portions4eare suspended from the bottom surface of the main body portion4aso as to be fitted into the respective locking through-holes3uformed in a part of the upper horizontal rib3fof which is positioned in the central space portion A1formed in the short side wall3. The triangular-prismatic horizontal projecting portion4eincludes horizontal perpendicular surfaces4e1extending perpendicularly to the main body portion4aand a horizontal inclined surface4e2inclined from the bottom surfaces of the main body portion4atoward the horizontal perpendicular surfaces4e1.

Moreover, a recess portion4fincluding opposite side surfaces4f1and a bottom surface4f2is formed in a central portion of the top surface of the main body portion4a. An engaging vertical piece4gconfigured to bridge the opposite side surfaces4f1is formed on the bottom surface4f2of the recess portion4f. The elastically deformable elastic locking piece3vsuspended from the rear surface of the upper-end horizontal flange3bof the short side wall3is locked on the engaging vertical piece4g.

Now, attachment of the lock member L to the short side wall3will be described mainly usingFIGS. 15 and 16.

First, the tip portion of the plate-like member20included in the paired lock bars Lb is inserted through the lock bar insertion hole3g′ formed in the closer-to-center coupling vertical rig3g, the lock bar insertion hole formed in the vertically long coupling block3i, the lock bar insertion hole3h′ formed in the closer-to-end coupling vertical rib3h, the lock bar insertion hole3c2′ formed in the upper-end vertical portion3c2of the end vertical rib3c, and the lock bar insertion hole3d1′ formed in the vertical end wall3d1of the short side wall-side engaging member3d, in this order. The vertical spring member22formed on each of the lock bars Lb is positioned in abutment with or close to the side surface3x1of the corresponding spring member abutting block3xprovided on a corner formed closer to the corresponding short side wall-side engaging member3dby parts of the corresponding spring receiving and supporting vertical rib3mand the upper horizontal rib3fwhich are formed in the central space portion A1. At this time, the inclined surface20bformed at the tip portion of the plate-like member20is positioned on the outer surface3a1side of the plate-like portion3aof the short side wall3. As described above, when the paired lock bars Lb are arranged in the central space portion A1of the short side wall3, an upper corner21a′ formed by the top surface21a1forming the cam hole portion21aand the upper end of the inclined surface21a3is positioned closer to the spring receiving and supporting vertical rib3m.

Then, the operation portion La is moved closer to the outer surface3a1of a part of the plate-like portion3aof the short side wall3which is positioned in the central space portion A1to fit the pivotal short shaft11bformed on the leading vertical surface11aof each of the horizontal arms11included in the operation portion La, into the fitting recess portion3j1of the corresponding pivotal short-shaft supporting block3jformed on a part of the plate-like portion3awhich is positioned in the central space portion A1of the short side wall3and close to the upper-end horizontal flange3b, as shown inFIGS. 15 and 17. Furthermore, each of the driven short shafts15formed on the operation main body10is inserted into the cam hole portion21aformed in the corresponding one of the cam plates21included in the lock bar Lb. Additionally, the operation portion14formed in the operation main body portion10is configured to be inserted into the operation portion insertion space portion A2formed so as to stride over the central portion of the upper-end horizontal flange3band the plate-like portion3a, both of which are included in the short side wall3. Moreover, the tip portion12bof each of the inclined spring members12formed in the central portion of the bottom surface of the operation main body10of the operation portion La is placed on the horizontal surface3n1′ forming the top surface3n1of the corresponding spring receiving and supporting block3nformed in the central space portion A1of the short side wall3.

As described above, when the operation portion14formed in the operation main body portion10of the operation portion La included in the lock member L is inserted, as described above, into the operation portion insertion space portion A2formed so as to stride over the central portion of the upper-end horizontal flange3band the plate-like portion3a, both of which are included in the short side wall3, the linear portion14cof the operation portion14is substantially flush with the inner surface3a2of the short side wall3. Furthermore, the inclined spring member protect piece13suspended from the bottom surface of the lower horizontal plate portion10bof the operation main body10included in the operation portion La is placed between the paired reinforcing vertical pieces3qformed in the central space portion A1formed in the short side wall3.

Furthermore, when the lock member L is attached to the short side wall3, the tip portion of the plate-like member20of each of the lock bars Lb projects from the vertical end wall3d1included in the short side wall-side engaging member3d. Moreover, the tip portion12bof each of the inclined spring members12formed in the central portion of the bottom surface of the operation main body10of the operation portion La is placed on the horizontal surface3n1′ forming the top surface3n1of the corresponding spring receiving and supporting block3nformed in the central space portion A1of the short side wall3. Moreover, when each of the driven short shafts15formed on the operation main body10of the operation portion La is inserted into the cam hole portion21adrilled in the cam plate21included in the corresponding lock bar Lb, the driven short shaft15is positioned close to the upper corner21a′ formed by the top surface21a1forming the corresponding cam hole portion21aand the upper end of the inclined surface21a3as shown inFIG. 18.

Moreover, when the lock member L is attached to the short side wall3as described above, the circular-arc operation portion14formed on the operation main body10of the lock member L is fitted into the operation portion insertion space portion A2formed in the central portion of the inner upper corner of the short side wall3of the folding container assembled in box form.

Then, the main body portion4aof the cover member4is placed opposite the outer surface3a1of a part of the plate-like portion3awhich is positioned in the central space portion A1formed in the short side wall3. Thereafter, the cover member4is moved closer to the short side wall3. Then, the insertion piece4cprojected from the top surface4b1of each of the upper-end block portions4bincluded in the cover member4is inserted into the cutout through-hole3tformed close to the corresponding one of the opposite ends of the corner formed by the upper-end horizontal flange3band plate-like portion3aof the short side wall3. Furthermore, the triangular-prismatic vertical projecting portion4dprojected from the lower end of each of the opposite vertical side surfaces4a1of the main body portion4aincluded in the cover member4is hooked on the inner edge3g1positioned closer to the lock bar insertion hole3g′ formed in corresponding one of the closer-to-center coupling vertical ribs3gformed on the short side wall3. Moreover, each of the triangular-prismatic horizontal projecting portions4esuspended from the bottom surface of the main body portion4aincluded in the cover member4is fitted into the corresponding one of the locking through-holes3uformed in a part of the upper horizontal rib3fwhich is positioned in the central space portion A1of the short side wall3. Furthermore, the engaging vertical piece4gbridging the opposite side surfaces4f1of the recess portion4fformed in the central portion of the top surface of the main body portion4aincluded in the cover member4is locked on the elastic locking piece3vsuspended from the rear surface of the upper-end horizontal flange3bof the short side wall3. Thus, the central space portion A1formed in the short side wall3is covered by the cover member4.

In the covering step in which the cover member4is attached so as to cover the central space portion A1formed in the above-described short side wall3, the following inclined surfaces are arranged on the outer surface3a1side of the plate-like portion3aforming the short side wall3: the vertical inclined surface4d2formed on the triangular-prismatic vertical projecting portion4dprojected from the lower end of each of the opposite vertical side surfaces4a1of the main body portion4aincluded in the cover member4and the horizontal inclined surface4e2of each of the triangular-prismatic horizontal projecting portions4esuspended from the bottom surface of the main body portion4a. In this state, when the cover member4is moved closer to the short side wall3, the vertical inclined surface4d2formed on the triangular-prismatic vertical projecting portion4dprojected from the lower end of each of the opposite vertical side surfaces4a1of the main body portion4aincluded in the cover member4comes into abutting contact with the corresponding one of the closer-to-center coupling vertical ribs3gformed in the central space portion A1formed in the short side wall3. Hence, the triangular-prismatic vertical projecting portion4dis guided via the vertical inclined surface4d2. This facilitates installation of the cover member4over the central space portion A1. Similarly, the horizontal inclined surface4e2of each of the triangular-prismatic horizontal projecting portions4esuspended from the bottom surface of the main body portion4aincluded in the cover member4comes into abutting contact with the tip of the upper horizontal rib3fof the short side wall3. Hence, the triangular-prismatic horizontal projecting portion4eis guided via the horizontal inclined surfaces4e2. This facilitates installation of the cover member4over the central space portion A1. Thus, as shown inFIG. 16, the cover4covers the central space portion A1formed in the short side wall3.

As described above, the cover member4covers the central space portion A1formed in the short side wall3. This prevents external exposure of the operation portion La and lock bars Lb included in the lock member L located in the central space portion A1formed over the outer surface3a1of the plate-like portion3a1of the short side wall3. Thus, the operation portion La and lock bars Lb included in the lock member L located in the central space portion A1can be prevented from being damaged by an external member. Furthermore, the cover member4allows the central space portion from being deformed by a load imposed from above when folding containers are stacked. As a result, the operation portion La and lock bars Lb included in the lock member L can be prevented from being damaged.

To assemble the folded folding container into box form as shown inFIG. 1, the operator first pivotally moves the long side walls2in a horizontal state in the vertical direction so that the long side walls2stand vertically. Then, the operator pivotally moves the short side walls3in a horizontal state in the vertical direction. However, during the step in which the short side walls3are pivotally moved in the vertical direction, the inclined surface20bformed at the tip portion of the plate-like member20of each of the lock bars Lb included in the lock member L attached to each the short side wall3comes into abutting contact with the vertical side wall2d1included in the corresponding one of the engaging recess portions2dformed in each of the long side walls2. In this state, the operator further pivotally moves the short side wall3in the vertical direction. Then, each of the inclined surfaces20bformed at the tip portion of the plate-like member20of the lock bar Lb is guided by the vertical side wall2d1of the corresponding one of the engaging recess portions2dformed in the long side wall2. At the same time, the paired lock bars Lb move closer to each other in the horizontal direction. Furthermore, the tip portion of each of the plate-like members20of the lock bar Lb is retracted from the corresponding one of the vertical side wall portions3d2included in the short side wall-side engaging member3d. In this manner, when the paired lock bars Lb move closer to each other in the horizontal direction, the cam hole portion21aof the cam plate21moves in the horizontal direction without coming into abutting contact with the driven short shaft15on the operation portion La. Furthermore, when the paired lock bars Lb move closer to each other in the horizontal direction, the tip of the vertical spring member22formed in each of the lock bar Lb is elastically deformed toward the corresponding one of the plate-like members20against the elastic force thereof as shown inFIG. 19.

Thereafter, the inclined surface20bformed at the tip portion of the plate-like member20of each of the lock bars Lb passes over the vertical side wall2d1of the corresponding one of the engaging recess portions2dformed in the long side wall2. Then, the paired lock bars Lb move away from each other in the horizontal direction by the elastic recovery force of the vertical spring member22formed in each of the lock bars Lb. The tip portion of the plate-like member20of each of the lock bars Lb is then inserted into the corresponding one of the engaging recess portions2dformed in the long side wall2as shown inFIG. 20.

Immediately before the tip portion of the plate-like member20of each of the lock bars Lb included in the lock member L attached to the above-described short side wall3is inserted into the corresponding one of the engaging recess portions2dformed in the long side wall2, the upper-end fitting projecting portion3e1formed on each of the short side wall-side engaging portion3dof the short side wall3is fitted into the upper-end fitting hole2e1formed at the upper end of the corresponding one of the long side wall-side engaging members2cof the long side wall2. Furthermore, the fitting projecting portion3e2formed on each of the short side wall-side engaging portions3dof the short side wall3is fitted into the fitting hole2e2formed in the corresponding one of the long side wall-side engaging members2cof the long side wall2.

As described above, simply by vertically raising the long side walls2in the horizontal state and then pivotally moving the short side walls3in the horizontal state in the vertical direction, the folded folding container can be assembled into box form as shown inFIG. 1without the need for the operator's operation of the lock member L attached to each of the short side walls3.

Furthermore, as described above, when the folding container is assembled into box form, the tip portion of the plate-like member20of each of the lock bars Lb included in the lock member L disposed on the short side wall3is inserted into the corresponding one of the engaging recess portions2dformed in the long side wall2as shown inFIG. 20. This prevents the short side walls3from being inadvertently brought down toward the bottom portion1.

Moreover, as described above, during the assembly of the folding container into box form, when the paired lock bars Lb move closer to each other in the horizontal direction, the cam hole portion21aof the cam plate21included in each of the lock bars Lb moves in the horizontal direction without coming into abutting contact with the corresponding one of the driven short shafts15of the operation portion La. This prevents the operation portion La from moving pivotally. Hence, each of the lock bars Lb only elastically deforms the vertical spring member22formed therein. This in turn reduces a load imposed when the paired lock bars Lb are moved closer to each other in the horizontal direction. Consequently, the operation of assembling the folding container is facilitated.

When the folding container is in assembled box form, the tip portion12bof each of the inclined spring members12formed in the central portion of the bottom surface of the operation main body10of the operation portion La is placed on the horizontal surface3n1′ forming the top surface3n1of the corresponding one of the spring receiving and supporting blocks3nformed in the central space portion A1of the short side wall3as shown inFIG. 17.

To fold the folding container assembled in box form, the operator first presses the finger on the top surface14aof the circular-arc operation portion of the operation portion La included in the lock member L attached to the short side wall3. The operator then pivotally moves the operation portion La inward downward in the folding container using, as pivotal-movement supporting points, the pivotal short shafts11bof the operation portion La fitted in the fitting recess portions3j1of the pivotal short-shaft supporting blocks3jformed on the part of the plate-like portion3awhich is positioned in the central space portion A1of the short side wall3. Then, as shown inFIG. 21, the tip portion12bof each of the inclined spring members12formed on the operation main body10of the operation portion La comes into abutting contact with the horizontal surface3n1forming the top surface3n1of the corresponding one of the spring receiving and supporting blocks3nformed on the short side wall3, and then with the inclined surfaces3n1″. Thus, the inclined spring members12are elastically deformed against the elastic force thereof, in a direction in which the tip portions12bof the inclined spring members12leave each other, in other words, in a direction in which the tip portion12bof each of the inclined spring members12approaches the operation main body10of the operation portion La. The downward pivotal movement of the operation portion La allows the driven short shaft15of each of the lock bars Lb positioned close to the upper corner21a′ of the cam hole portion21aformed in the cam plate21of the corresponding one of the lock bars Lb to move downward along the inclined surface21a3of the cam hole portion21aas shown inFIG. 22. Thus, when each of the driven short shafts15moves downward along the inclined surface21a3of the corresponding one of the cam hole portions21a, the paired lock bars Lb move closer to each other in the horizontal direction to allow the tip portion of the plate-like member20of each of the lock bars Lb to be discharged from the corresponding one of the engaging recess portions2dformed in the long side wall2. Hence, the short side wall3locked on the long side wall2via the lock member L is unlocked. Then, the short side walls3are brought down toward the bottom portion1and laid on top of the bottom portion1and on top of each other. Thereafter, the long side walls2are brought down toward the bottom portion and laid on top of the short side walls3stacked on the bottom portion1and on top of each other. In this manner, the folding container assembled in box form can be folded.

As described above, the operation portion La included in the lock member L is pivotally moved downward using, as pivotal-movement supporting points, the pivotal short shafts11of the operation portion La fitted in the fitting recess portions3j1of the pivotal short-shaft supporting blocks3jformed on the part of the plate-like portion3awhich is positioned in the central space portion A1of the short side wall3. Thus, regardless of where on the top surface14aof the operation portion14formed on the operation main body10included in the operation portion La, the operator's finger is located, the laterally paired lock bars Lb, disposed across the operation portion La, have the same horizontal travel distance. This enables reliable cancellation of the lock state in which the short side walls3and the long side walls2are locked via the lock member L.

Furthermore, as described above, during the assembly of the folding container into box form, when the paired lock bars Lb move closer to each other in the horizontal direction, the cam hole portion21aof the cam plate21included in each of the lock bars Lb moves in the horizontal direction without coming into abutting contact with the corresponding one of the driven short shafts15of the operation portion La. This prevents the operation portion La from moving pivotally. Hence, each of the lock bars Lb only elastically deforms the vertical spring member22formed therein. This in turn reduces a load imposed when the paired lock bars Lb are moved closer to each other in the horizontal direction. Consequently, the operation of assembling the folding container is facilitated.

Moreover, the operation portion La and lock bars Lb included in the lock member L located in the central space portion A1formed in the short side wall3are covered by the cover member4. This prevents the operation portion La and lock bars Lb included in the lock member L located in the central space portion A1from being exposed to the outside of the short side wall3. Therefore, the operation portion La and lock bars Lb included in the lock member L located in the central space portion A1can be prevented from being damaged by an external member.

Moreover, when carrying the folding container assembled in box form, the operator holds the hand on the bottom surface of the upper horizontal rib3fof the short side wall3or places the hand in a handling recess portion or a through-hole formed in a part of plate-like portion3awhich is located below and close to the upper horizontal rib3f. However, according to the present invention, the operation portion La of the lock member L operated by the operator is disposed in the operation portion insertion space portion A2formed in the central portion of the inner upper corner of the short side wall3and is configured to move pivotally inward of the folding container. This reliably prevents the operator from inadvertently touching the operation portion La to pivotally move the operation portion downward.

A rounded-off portion12b1is preferably formed on a corner of the tip portion12bof each of the inclined spring members12formed in the operation main body10of the operation portion La which corner is positioned closer to the inclined surface3n1″ of the corresponding one of the spring receiving and supporting blocks3n. The formation of such a rounded-off portion12b1allows the inclined spring member12to move smoothly from the horizontal surface3n1′ to inclined surface3n1″ of the spring receiving and supporting block3n. This also enables a reduction in the movement of the inclined spring member12toward the spring receiving and supporting vertical rib3m.

In the above-described embodiment, the operation portion La is pivotally moved downward using, as pivotal-movement supporting points, the pivotal short shafts11of the operation portion La fitted in the fitting recess portions3j1of the pivotal short-shaft supporting blocks3jformed on the plate-like portion3aof the short side wall3. However, as is well known and described in U.S. Pat. No. 6,290,081 and the like, the operation portion may be configured to be movable upward and downward.