CA1174411A - Method and mold for making an improved egg carton - Google Patents
Method and mold for making an improved egg cartonInfo
- Publication number
- CA1174411A CA1174411A CA000444364A CA444364A CA1174411A CA 1174411 A CA1174411 A CA 1174411A CA 000444364 A CA000444364 A CA 000444364A CA 444364 A CA444364 A CA 444364A CA 1174411 A CA1174411 A CA 1174411A
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- Canada
- Prior art keywords
- male
- cover
- female
- carton
- key
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
METHOD AND MOLD FOR MAKING AN IMPROVED EGG CARTON
An inwardly offset surface of the cover of a carton is cut in a plane transverse to the top of the cover. A protrusion on the bottom surface of a complementary recess in the latch flap extends through the hole to latch the carton with the protrusion being within the cover recess to prevent accidental opening of the carton. The mold for producing the carton cuts the hole thermoforming by relative movement between a male key mounted in the male mold member and a female key mounted in the female mold member. Both keys have flat surfaces transverse to the closing motion of the molds. These flat surfaces are biased into engagement one with the other so that the plastic is cut in a shearing action.
An inwardly offset surface of the cover of a carton is cut in a plane transverse to the top of the cover. A protrusion on the bottom surface of a complementary recess in the latch flap extends through the hole to latch the carton with the protrusion being within the cover recess to prevent accidental opening of the carton. The mold for producing the carton cuts the hole thermoforming by relative movement between a male key mounted in the male mold member and a female key mounted in the female mold member. Both keys have flat surfaces transverse to the closing motion of the molds. These flat surfaces are biased into engagement one with the other so that the plastic is cut in a shearing action.
Description
~ ~74~
METHOD AND MOLD FOR MAKING AN IMPROVED EGG CARTON
This invention relates to an improved egg carton, and tomethods of and molds for making it.
~ U.S. Patent 2,990,094 shows an egg carton with a latch of the type in which a "button" on the latch flap extends through a hole in the flat surface of the cover to latch the carton closed.
Problems were experienced with this type of egg carton because persons picking the carton up by the cover inadvertently pushed the protrusion out of engagement with the hole, thereby unlatching the egg carton with disastrous results.
Cartons of the type shown in U.S. Patent 3,648,916 -Commisso ob~iate this problem. This latch flap has a locking recess which includes a latch bar across the top thereof. The cover has recesses which are complementary to the recess on the latch flap. A
hole is cut across the recess in the cover. This hole extends from the flat surface of the front of the cover down into the recess, across the recess, and back to the front surface of the cover. In the closed position, the latching bar fits into this hole to hold the cover in the closed position. This latching mechanism has the advantage that it is recessed. Therefore, when the carton is grasped by the cover, there is no possibility of inadvertently unlatching the cover.
Egg cartons of this type are thermoformed from a sheet of preheated polystyrene foam. In egg cartons of the type shown in the Commisso patent, it is important that the hole in the cover extend all the way from the front surface of the cover to the bottom of the recess, and back to the front surface. Only when the hole is completely extended in this manner, will the latching bar fit into the hole to lock the carton. Because of this, cartons of the type shown in the Commisso patent have heretofore been formed in two steps. The first step is the thermoforming operation in which two ~ iJ4~
mold members close to form the carton. The second step is a punching operation which punches the hole in the cover. It is desirable to eliminate the separate punching step so that the carton is formed with a hole in the cover during the molding operation.
U.S. Patents 3,845,187 and 3,862,817 Dahlberg describe a thermoforming method and molds for cutting a hole in the carton at the same time that the carton is formed. An ~ttempt is made to tear the edges of the hole to form the portion of the hole between the cover and the bottom of the recess so that the latching bar will mate with the edge of the hole. Tearing plastic material is unpredictable and results ln many cartons with inoperable locks.
Furthermore, a torn edge on the hole is unsightly.
A more desirable hole is formed by the process and molds shown in U.S. Patent 43108,941 - Kermoian, 4,182,848 - Irwin and 4,143,111 - Irwin. As shown in these patents, dies in the male and female mold members shear the plastic during the closing of the molds to cut a hole in the cover.
It is an object of the present invencion to cut a hole in the bnttom of a recess in the cover of a carton during molding to form a recessed latch whieh will not be inadvertently unlocked.
In accordance with one embcdiment of the present invention, an egg carton has a hole cut in an inwardly offset surface of a recess in the front wall of a cover, which cut is in a plane transverse to the top of the cover. A protrusion on the bottom surface of the recess in the latch flap extends through a complementary hole in the inwardly offset surface of the cover to latch the carton in the closed position. The carton has the advantage of a recessed latch which is not easily opened accidentally. It has the further advantage of allowing the cutting of the hole in the cover during the molding of the carton. This eliminates tearing of the sover or the requirement of a separate step for punching out the portion of the cover between the inwardly offset surface and the front surface of the cover.
~.~'7'~
F-1021 ~3~
In accordance with another e~x~iment of the invention, the protrusion of the latch flap has a sloping surface angled at the same angle as the beveled edge of the latch ~lap to aid in closing.
The sloping surface of the protrusion terminates in a sharp undercut which provides good elosure strength, but the carton is easier to open. The invention is carried out by closing a male mold memoer and a female mold member on a preheated flat sheet of polystyrene foam to produce a carton having a cover and a latch flap. A male cutting key mounted on the male mold member has a cutting surface parallel to the closing motion between the male and female mold members. A female cutting key is mounted in the ~emale mold member and has a flat cutting surface which is also parallel to the closing motion between the male and ~male mold members. The cutting keys in the male and female mold members are biased nne against the other during the closing motion of the mold members. The flat surface of the cutting keys shear a hole in the cover transverse to the top of the cover during closing of the mold members. The mold has the advantage of not requiring precise alignment of the male and female mold members. Therefore, the cartons of the present invention can be produced on existing molds, which frequently do not have close fitting tolerances, by merely fitting the molds with the male and female cutting keys of the pre~ent invention. Upon closure of the mold members, the female cutting key engages a beveled edge on the male cutting key. The engagement moves the male cutting key against the bias in a motion transverse to the closing motion. There~ore, good registration between the flat cutting surfaces of the cutting keys is obtained regardless of the closing tolerance bet~een the male and ~emale mold members~
The invention, in one aspect, then, resides in a carton adapted for the packaging of eggs and the like comprising~
(a) a bottom tray formed to define a plurality of cells for reception of packaged articles and of a depth such that the articles are enclosed thereby for a portion less than their vertical dimension as packaged;
:~:1'7'~
-3a-(b) a dished cover resiliently hinged to the rear upper edge of the tray and having a front wall, a back wall, and end walls fixed to each other and to a top for the co~er, all of such dimensions situated so that the packaged articles are substantially enclosed within the edges of the tray, the front wall lying primarily in a plane sloping inwardly toward the top;
(c) a latching flap hinged to the front upper edge of the tray by resilient means biasing the flap toward an outward position;
(d) a plurality of recesses in said fron wall of said cover each having a surface which is inwardly offset with respect to said front wall and lying in a plane sloping upwardly towards said top, each recess having a hole in said surface cut in a plane that extends perpendicular to the plane of the top of the cover, and said hole being substantially confined within said surface;
(e) a plurality of recesses in sai.d latching flap engageable with respective recesses in said front wall of said cover; and (f) a plurality of protrusions at the free edge of said latching flap opposite said flap hinge, each protrusion extending through a respective one of the holes in the inwardly offset surface of said cover to latch said carton in the closed position.
The invention, in another aspect, resides in a process for producing the previously defined carton, which process comprises the following steps:
providing a relatively flat oriented sheet of polystyrene foam;
preheating the sheet to at least its forming temperature;
thermoforming the preheated sheet by bridging together a male mold member and a female mold member to form regions (a) and (c) to (f) of the carton and form the dished cover (b) apart from the holes therein;
7~
-3b-shearing a hole in the surface of the co~er which is inwardly offset with respect to the front wall of the cover during thermoforming by relative movement between a flat cutting surface of a male key mounted in said mold member and a flat cutting surface of a female key mounted in said female mold member, said movement being parallel to the closing motion between said male and female members;
biasing said flat cutting surface of said male key against said flat cutting surface of said female key to produce shearing of said sheet between said key;- and engaging an edge of said female cutting key with a beveled edge of said male cutting key to move said male key perpendicular to the closing motion between said male and female mold members whereby engagement between the flat surfaces of said male and female keys is obtained regardless of the alignment between said male and female mold members.
These aspects of the invention are disclosed, and are also claimed, in Canadian Patent Application No.
409,094 - Daines - of which the present application is a divisional.
The present invention, in a further aspect, resides in a mold for producing the above-defined carton, which mold comprises:
(A) a male mold member;
(s) a female mold member;
(C) means for closing the male and female mold members on a preheated flat sheet of polystyrene foam to form regions (a) and (c) to (f) of the carton and to form the dished cover (b) apa.rt from the holes therein;
(D) a male cutting key mounted in said male mold member and having a flat cutting surface parallel to the closing motion between said male and female mold members, (E) a female key mounted in said female mold member and having a flat cutting surface parailel to the closing motion between said male and female mold members;
-3c-(F) said male cutting key ha~ing a be~eled edge along the surface which first engages said female key during closing motion between said male and female mold members; and (G) means for biasing the flat surfaces of said male and female keys one against the other, the engagement of said female key with said beveled edge producing a motion of said male key perpendicular to the closing motion between male and female mold members whereby engagement between the flat surfaces of said male and female keys is obtained regardless of the alignment between said male and female mold members during the closing motion of said mold members so that said engagement cuts a hole in said cover perpendicular to the top of said cover.
The foregoing and other objects, features and advantages of the invention will be better understood from the following more detailed description and appended claims.
In the drawings:
Fig. 1 shows a portion of the latch flap and the cover which has the latch of the presend invention;
~7~
Fig. 2 is a view of the carton in the closed position;
Figs~ 3 and 4 are sectional views of the carton in the closed and open position respectively;
Fig. ~A shows a carton of the type shown in the a~orementioned Commisso patent;
Fig. 5B is a comparable view of the carton of one aspect of the present invention;
Fig~ 6 is a partial cross~section through the male and female mold members which are in the open position;
Fig. 7 is similar to Fig. 6 with the mold members closed;
Fig. 8 shows the male key and male key holder;
Fig. 9 shows the female key and female key holder;
Fig. 9A is a section on the lines A-A of Fig. 9;
Fig. 10 is a top view of the male mold member showing the outline of the male key holder; and Fig. 11 is a side view of the male mold member.
Referring to Figs. 1-4, the egg carton of one aspect of the present invention i~cludes a bottom tray 11 formed to dcfine a plurality of cells for receiving eggs. A dished cover 12 is resiliently hinged to the rear upper edge of the tray. It has a front wall 13, a top 1~ a back wall and end walls fixed to the top. The front wall 13 slopes in a plane inwardly toward the top. A latching flap 15 is resiliently hinged to the front upper edge of the tray 11 and with a bias of the ~lap toward an outward position. Recesses 16 and 17 in the front wall of the cover have a surface 18 which is inward~y offset with respect to the front wall. A hole lg in this surface is cut in a plane which is transverse to the top 14 of the cover. A
recess 20 in the latch flap 15 complements the recess 16 in the front wall of the cover~ A protrusion 21 on ~he bottom surface of the recess ~0 extends through the complementary hole 19 in the inwardly offset surface of the cover. This latches the carton when it is in the closed position as ~hown in Fig. 3. The carton of one aspect of the ~ 7~
present invention has the advantage that when in the closedposition, the protrusion 21 is within the confines of the recess 16 so that it cannot be inadvertently unlatched by grasping thP cover of the carton.
The structure of the protrusion 21 is an impro~ement over the button type latches shown in the aforementioned '094 patent.
The protrusion 21 has a sloping surface 21a which is angled at the same angle as the beveled edge 15a on the latch flap 15. This sloping surface terminates in a sharp undercut which forms the latching surface.
The advantages of the present invention over the carton of the Commisso patent are best demonstrated by comparing Figs. 5A and 5B. In Fig. 5A a latch bar 22 at the top of the walled recess 23 in the latch flap forms the male locking member. The hole 24 in the cover is cut from the ~ront surface of the cover to the back to the inwardly of~set surface 25, and then back to the front surface~
Only if the hole is cut completely to the front surface of the cover, will the latch bar 22 fit through the hole to provide a positive engagement. On the other hand, the hole 19 in the cover of the carton of the present invention is flush with the inwardly offset surface 18. This hole can be simply sheared during the molding of the egg carton. Good latching is obtained with this type of hole by reason of the protrusion 21 extending through the hole 19.
Referring to Figs. 6-12, the mold forming this egg carton includes a male mold member 27 and a female mold member 28. These members are closed one with respect to the other on a preheated flat sheet of polystyrene foam to form a carton cover, the outline of which is shown in fig. 7.
A male cutting key 29 is mounted in a male key holder 30 which is in turn mounted in the male mold member 27. The male cutting key 29 is biased toward the left by the spring 31. A cover 32 (Fig. 8) for the male cutting key 29 ensures that it moves only in a direction transverse to the closing motion of the mold members.
~ '7~
A female key 33 is mounted in a female key holder 34 whichis in turn mounted on the female mold member 28. The female cutting key has a flat cutting surface 35 which is parallel to the closing motion of the mold members. The male cutting key 29 has a mating flat cutting surface 3~ parallel to the closing motion of the mold members. The male key has a beveled edge ~7 along the surface which first engages the female key during closing motion between the male and female mold members~ The engagement of the female key 33 with the beveled edge 37 produces a motion of the male key toward the right (Fig. 6) against the bias of the spring and transverse to the closing motion between the male and female mold members. This transverse motion is su~ficient to ensure com,olete engagement between the flat surfaces ~5 and 36 of the male and female cutting keys during Further closing motion of the mold members. The bias between these flat surfaces ensures a good shearing action in a classic scissor-like motion in which the two cutting surfaces are biased oblique to one another. The beveled edge and bias also ensure that this action w~ll be present regardless of the alignment between the male and female mold members.
While particular embcdiments have been shown and described, modifications are within the true spirit and scope of the invention. The appended claim is, therefore, intended to cover all such modifications.
METHOD AND MOLD FOR MAKING AN IMPROVED EGG CARTON
This invention relates to an improved egg carton, and tomethods of and molds for making it.
~ U.S. Patent 2,990,094 shows an egg carton with a latch of the type in which a "button" on the latch flap extends through a hole in the flat surface of the cover to latch the carton closed.
Problems were experienced with this type of egg carton because persons picking the carton up by the cover inadvertently pushed the protrusion out of engagement with the hole, thereby unlatching the egg carton with disastrous results.
Cartons of the type shown in U.S. Patent 3,648,916 -Commisso ob~iate this problem. This latch flap has a locking recess which includes a latch bar across the top thereof. The cover has recesses which are complementary to the recess on the latch flap. A
hole is cut across the recess in the cover. This hole extends from the flat surface of the front of the cover down into the recess, across the recess, and back to the front surface of the cover. In the closed position, the latching bar fits into this hole to hold the cover in the closed position. This latching mechanism has the advantage that it is recessed. Therefore, when the carton is grasped by the cover, there is no possibility of inadvertently unlatching the cover.
Egg cartons of this type are thermoformed from a sheet of preheated polystyrene foam. In egg cartons of the type shown in the Commisso patent, it is important that the hole in the cover extend all the way from the front surface of the cover to the bottom of the recess, and back to the front surface. Only when the hole is completely extended in this manner, will the latching bar fit into the hole to lock the carton. Because of this, cartons of the type shown in the Commisso patent have heretofore been formed in two steps. The first step is the thermoforming operation in which two ~ iJ4~
mold members close to form the carton. The second step is a punching operation which punches the hole in the cover. It is desirable to eliminate the separate punching step so that the carton is formed with a hole in the cover during the molding operation.
U.S. Patents 3,845,187 and 3,862,817 Dahlberg describe a thermoforming method and molds for cutting a hole in the carton at the same time that the carton is formed. An ~ttempt is made to tear the edges of the hole to form the portion of the hole between the cover and the bottom of the recess so that the latching bar will mate with the edge of the hole. Tearing plastic material is unpredictable and results ln many cartons with inoperable locks.
Furthermore, a torn edge on the hole is unsightly.
A more desirable hole is formed by the process and molds shown in U.S. Patent 43108,941 - Kermoian, 4,182,848 - Irwin and 4,143,111 - Irwin. As shown in these patents, dies in the male and female mold members shear the plastic during the closing of the molds to cut a hole in the cover.
It is an object of the present invencion to cut a hole in the bnttom of a recess in the cover of a carton during molding to form a recessed latch whieh will not be inadvertently unlocked.
In accordance with one embcdiment of the present invention, an egg carton has a hole cut in an inwardly offset surface of a recess in the front wall of a cover, which cut is in a plane transverse to the top of the cover. A protrusion on the bottom surface of the recess in the latch flap extends through a complementary hole in the inwardly offset surface of the cover to latch the carton in the closed position. The carton has the advantage of a recessed latch which is not easily opened accidentally. It has the further advantage of allowing the cutting of the hole in the cover during the molding of the carton. This eliminates tearing of the sover or the requirement of a separate step for punching out the portion of the cover between the inwardly offset surface and the front surface of the cover.
~.~'7'~
F-1021 ~3~
In accordance with another e~x~iment of the invention, the protrusion of the latch flap has a sloping surface angled at the same angle as the beveled edge of the latch ~lap to aid in closing.
The sloping surface of the protrusion terminates in a sharp undercut which provides good elosure strength, but the carton is easier to open. The invention is carried out by closing a male mold memoer and a female mold member on a preheated flat sheet of polystyrene foam to produce a carton having a cover and a latch flap. A male cutting key mounted on the male mold member has a cutting surface parallel to the closing motion between the male and female mold members. A female cutting key is mounted in the ~emale mold member and has a flat cutting surface which is also parallel to the closing motion between the male and ~male mold members. The cutting keys in the male and female mold members are biased nne against the other during the closing motion of the mold members. The flat surface of the cutting keys shear a hole in the cover transverse to the top of the cover during closing of the mold members. The mold has the advantage of not requiring precise alignment of the male and female mold members. Therefore, the cartons of the present invention can be produced on existing molds, which frequently do not have close fitting tolerances, by merely fitting the molds with the male and female cutting keys of the pre~ent invention. Upon closure of the mold members, the female cutting key engages a beveled edge on the male cutting key. The engagement moves the male cutting key against the bias in a motion transverse to the closing motion. There~ore, good registration between the flat cutting surfaces of the cutting keys is obtained regardless of the closing tolerance bet~een the male and ~emale mold members~
The invention, in one aspect, then, resides in a carton adapted for the packaging of eggs and the like comprising~
(a) a bottom tray formed to define a plurality of cells for reception of packaged articles and of a depth such that the articles are enclosed thereby for a portion less than their vertical dimension as packaged;
:~:1'7'~
-3a-(b) a dished cover resiliently hinged to the rear upper edge of the tray and having a front wall, a back wall, and end walls fixed to each other and to a top for the co~er, all of such dimensions situated so that the packaged articles are substantially enclosed within the edges of the tray, the front wall lying primarily in a plane sloping inwardly toward the top;
(c) a latching flap hinged to the front upper edge of the tray by resilient means biasing the flap toward an outward position;
(d) a plurality of recesses in said fron wall of said cover each having a surface which is inwardly offset with respect to said front wall and lying in a plane sloping upwardly towards said top, each recess having a hole in said surface cut in a plane that extends perpendicular to the plane of the top of the cover, and said hole being substantially confined within said surface;
(e) a plurality of recesses in sai.d latching flap engageable with respective recesses in said front wall of said cover; and (f) a plurality of protrusions at the free edge of said latching flap opposite said flap hinge, each protrusion extending through a respective one of the holes in the inwardly offset surface of said cover to latch said carton in the closed position.
The invention, in another aspect, resides in a process for producing the previously defined carton, which process comprises the following steps:
providing a relatively flat oriented sheet of polystyrene foam;
preheating the sheet to at least its forming temperature;
thermoforming the preheated sheet by bridging together a male mold member and a female mold member to form regions (a) and (c) to (f) of the carton and form the dished cover (b) apart from the holes therein;
7~
-3b-shearing a hole in the surface of the co~er which is inwardly offset with respect to the front wall of the cover during thermoforming by relative movement between a flat cutting surface of a male key mounted in said mold member and a flat cutting surface of a female key mounted in said female mold member, said movement being parallel to the closing motion between said male and female members;
biasing said flat cutting surface of said male key against said flat cutting surface of said female key to produce shearing of said sheet between said key;- and engaging an edge of said female cutting key with a beveled edge of said male cutting key to move said male key perpendicular to the closing motion between said male and female mold members whereby engagement between the flat surfaces of said male and female keys is obtained regardless of the alignment between said male and female mold members.
These aspects of the invention are disclosed, and are also claimed, in Canadian Patent Application No.
409,094 - Daines - of which the present application is a divisional.
The present invention, in a further aspect, resides in a mold for producing the above-defined carton, which mold comprises:
(A) a male mold member;
(s) a female mold member;
(C) means for closing the male and female mold members on a preheated flat sheet of polystyrene foam to form regions (a) and (c) to (f) of the carton and to form the dished cover (b) apa.rt from the holes therein;
(D) a male cutting key mounted in said male mold member and having a flat cutting surface parallel to the closing motion between said male and female mold members, (E) a female key mounted in said female mold member and having a flat cutting surface parailel to the closing motion between said male and female mold members;
-3c-(F) said male cutting key ha~ing a be~eled edge along the surface which first engages said female key during closing motion between said male and female mold members; and (G) means for biasing the flat surfaces of said male and female keys one against the other, the engagement of said female key with said beveled edge producing a motion of said male key perpendicular to the closing motion between male and female mold members whereby engagement between the flat surfaces of said male and female keys is obtained regardless of the alignment between said male and female mold members during the closing motion of said mold members so that said engagement cuts a hole in said cover perpendicular to the top of said cover.
The foregoing and other objects, features and advantages of the invention will be better understood from the following more detailed description and appended claims.
In the drawings:
Fig. 1 shows a portion of the latch flap and the cover which has the latch of the presend invention;
~7~
Fig. 2 is a view of the carton in the closed position;
Figs~ 3 and 4 are sectional views of the carton in the closed and open position respectively;
Fig. ~A shows a carton of the type shown in the a~orementioned Commisso patent;
Fig. 5B is a comparable view of the carton of one aspect of the present invention;
Fig~ 6 is a partial cross~section through the male and female mold members which are in the open position;
Fig. 7 is similar to Fig. 6 with the mold members closed;
Fig. 8 shows the male key and male key holder;
Fig. 9 shows the female key and female key holder;
Fig. 9A is a section on the lines A-A of Fig. 9;
Fig. 10 is a top view of the male mold member showing the outline of the male key holder; and Fig. 11 is a side view of the male mold member.
Referring to Figs. 1-4, the egg carton of one aspect of the present invention i~cludes a bottom tray 11 formed to dcfine a plurality of cells for receiving eggs. A dished cover 12 is resiliently hinged to the rear upper edge of the tray. It has a front wall 13, a top 1~ a back wall and end walls fixed to the top. The front wall 13 slopes in a plane inwardly toward the top. A latching flap 15 is resiliently hinged to the front upper edge of the tray 11 and with a bias of the ~lap toward an outward position. Recesses 16 and 17 in the front wall of the cover have a surface 18 which is inward~y offset with respect to the front wall. A hole lg in this surface is cut in a plane which is transverse to the top 14 of the cover. A
recess 20 in the latch flap 15 complements the recess 16 in the front wall of the cover~ A protrusion 21 on ~he bottom surface of the recess ~0 extends through the complementary hole 19 in the inwardly offset surface of the cover. This latches the carton when it is in the closed position as ~hown in Fig. 3. The carton of one aspect of the ~ 7~
present invention has the advantage that when in the closedposition, the protrusion 21 is within the confines of the recess 16 so that it cannot be inadvertently unlatched by grasping thP cover of the carton.
The structure of the protrusion 21 is an impro~ement over the button type latches shown in the aforementioned '094 patent.
The protrusion 21 has a sloping surface 21a which is angled at the same angle as the beveled edge 15a on the latch flap 15. This sloping surface terminates in a sharp undercut which forms the latching surface.
The advantages of the present invention over the carton of the Commisso patent are best demonstrated by comparing Figs. 5A and 5B. In Fig. 5A a latch bar 22 at the top of the walled recess 23 in the latch flap forms the male locking member. The hole 24 in the cover is cut from the ~ront surface of the cover to the back to the inwardly of~set surface 25, and then back to the front surface~
Only if the hole is cut completely to the front surface of the cover, will the latch bar 22 fit through the hole to provide a positive engagement. On the other hand, the hole 19 in the cover of the carton of the present invention is flush with the inwardly offset surface 18. This hole can be simply sheared during the molding of the egg carton. Good latching is obtained with this type of hole by reason of the protrusion 21 extending through the hole 19.
Referring to Figs. 6-12, the mold forming this egg carton includes a male mold member 27 and a female mold member 28. These members are closed one with respect to the other on a preheated flat sheet of polystyrene foam to form a carton cover, the outline of which is shown in fig. 7.
A male cutting key 29 is mounted in a male key holder 30 which is in turn mounted in the male mold member 27. The male cutting key 29 is biased toward the left by the spring 31. A cover 32 (Fig. 8) for the male cutting key 29 ensures that it moves only in a direction transverse to the closing motion of the mold members.
~ '7~
A female key 33 is mounted in a female key holder 34 whichis in turn mounted on the female mold member 28. The female cutting key has a flat cutting surface 35 which is parallel to the closing motion of the mold members. The male cutting key 29 has a mating flat cutting surface 3~ parallel to the closing motion of the mold members. The male key has a beveled edge ~7 along the surface which first engages the female key during closing motion between the male and female mold members~ The engagement of the female key 33 with the beveled edge 37 produces a motion of the male key toward the right (Fig. 6) against the bias of the spring and transverse to the closing motion between the male and female mold members. This transverse motion is su~ficient to ensure com,olete engagement between the flat surfaces ~5 and 36 of the male and female cutting keys during Further closing motion of the mold members. The bias between these flat surfaces ensures a good shearing action in a classic scissor-like motion in which the two cutting surfaces are biased oblique to one another. The beveled edge and bias also ensure that this action w~ll be present regardless of the alignment between the male and female mold members.
While particular embcdiments have been shown and described, modifications are within the true spirit and scope of the invention. The appended claim is, therefore, intended to cover all such modifications.
Claims
1. A mold for the production of a carton adapted for the packaging of eggs and the like comprising (a) a bottom tray formed to define a plurality of cells for reception of packaged articles and of a depth such that the articles are enclosed thereby for a portion less than their vertical dimension as packaged;
(b) a dished cover resiliently hinged to the rear upper edge of the tray and having a front wall, a back wall, and end walls fixed to each other and to a top for the cover, all of such dimensions situated so that the packaged articles are substantially enclosed within the edges of the tray, the front wall lying primarily in a plane sloping inwardly toward the top;
(c) a latching flap hinged to the front upper edge of the tray by resilient means biasing the flap toward an outward position;
(d) a plurality of recesses in said front wall of said cover each having a surface which is inwardly offset with respect to said front wall and lying in a plane sloping upwardly towards said top, each recess having a hole in said surface cut in a plane that extends perpendicular to the plane of the top of the cover, and said hole being substantially confined within said surface;
(e) a plurality of recesses in said latching flap engageable with respective recesses in said front wall of said cover; and (f) a plurality of protrusions at the free edge of said latching flap opposite said flap hinge, each protrusion extending through a respective one of the holes in the inwardly offset surface of said cover to latch said carton in the closed position;
which mold comprises:
(A) a male mold member;
(B) a female mold member;
(C) means for closing the male and female mold members on a preheated flat sheet of polystyrene foam to form regions (a) and (c) to (f) of the carton and to form the dished cover (b) apart from the holes therein;
(D) a male cutting key mounted in said male mold member and having a flat cutting surface parallel to the closing motion between said male and female mold members;
(E) a female key mounted in said female mold member and having a flat cutting surface parallel to the closing motion between said male and female mold ;
(F) said male cutting key having a beveled edge along the surface which first engages said female key during closing motion between said male and female mold members; and (G) means for biasing the flat surfaces of said male and female keys one against the other, the engagement of said female key with said beveled edge producing a motion of said male key perpendicular to the closing motion between male and female mold members whereby engagement between the flat surfaces of said male and female keys is obtained regardless of the alignment between said male and female mold members during the closing motion of said mold members so that said engagement cuts a hole in said cover perpendicular to the top of said cover.
(b) a dished cover resiliently hinged to the rear upper edge of the tray and having a front wall, a back wall, and end walls fixed to each other and to a top for the cover, all of such dimensions situated so that the packaged articles are substantially enclosed within the edges of the tray, the front wall lying primarily in a plane sloping inwardly toward the top;
(c) a latching flap hinged to the front upper edge of the tray by resilient means biasing the flap toward an outward position;
(d) a plurality of recesses in said front wall of said cover each having a surface which is inwardly offset with respect to said front wall and lying in a plane sloping upwardly towards said top, each recess having a hole in said surface cut in a plane that extends perpendicular to the plane of the top of the cover, and said hole being substantially confined within said surface;
(e) a plurality of recesses in said latching flap engageable with respective recesses in said front wall of said cover; and (f) a plurality of protrusions at the free edge of said latching flap opposite said flap hinge, each protrusion extending through a respective one of the holes in the inwardly offset surface of said cover to latch said carton in the closed position;
which mold comprises:
(A) a male mold member;
(B) a female mold member;
(C) means for closing the male and female mold members on a preheated flat sheet of polystyrene foam to form regions (a) and (c) to (f) of the carton and to form the dished cover (b) apart from the holes therein;
(D) a male cutting key mounted in said male mold member and having a flat cutting surface parallel to the closing motion between said male and female mold members;
(E) a female key mounted in said female mold member and having a flat cutting surface parallel to the closing motion between said male and female mold ;
(F) said male cutting key having a beveled edge along the surface which first engages said female key during closing motion between said male and female mold members; and (G) means for biasing the flat surfaces of said male and female keys one against the other, the engagement of said female key with said beveled edge producing a motion of said male key perpendicular to the closing motion between male and female mold members whereby engagement between the flat surfaces of said male and female keys is obtained regardless of the alignment between said male and female mold members during the closing motion of said mold members so that said engagement cuts a hole in said cover perpendicular to the top of said cover.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000444364A CA1174411A (en) | 1981-09-08 | 1983-12-28 | Method and mold for making an improved egg carton |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29968381A | 1981-09-08 | 1981-09-08 | |
| US299,683 | 1981-09-08 | ||
| CA000409094A CA1166202A (en) | 1981-09-08 | 1982-08-10 | Method and mold for making an improved egg carton |
| CA000444364A CA1174411A (en) | 1981-09-08 | 1983-12-28 | Method and mold for making an improved egg carton |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000409094A Division CA1166202A (en) | 1981-09-08 | 1982-08-10 | Method and mold for making an improved egg carton |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1174411A true CA1174411A (en) | 1984-09-18 |
Family
ID=27167272
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000444364A Expired CA1174411A (en) | 1981-09-08 | 1983-12-28 | Method and mold for making an improved egg carton |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1174411A (en) |
-
1983
- 1983-12-28 CA CA000444364A patent/CA1174411A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |