Differential pressure synthetic plastic forming machine and method with formed article carrier means

• US 4,464,329 A
• Filed: 07/01/1982
• Issued: 08/07/1984
• Est. Priority Date: 07/01/1982
• Status: Expired due to Fees

• Current Assignee: Leesona Corporation Beaverton MI A Corporation of
• Original Assignee: Leesona Corp.
• Inventors: Whiteside, Robert C., Greynolds, Fred L.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): Lorin, Hubert C.
• Application Number:
  US06/394,258
• Time in Patent Office: 768 Days
• Field of Search: 264/544, 264/550, 264/554, 264/553, 264/551, 264/403.1, 425/422, 425/444, 425/164, 425/166, 425/167, 425/176, 425/235, 425/236, 425/351, 425/388, 425/387.1, 425/302.1
• US Class Current: 264/544
• CPC Class Codes: B29C 51/04 Combined thermoforming and prestretching, e.g. biaxial stretching
• CPC Class Codes: B29C 51/10 Forming by pressure difference, e.g. vacuum
• CPC Class Codes: B29C 51/32 having cutting means
• CPC Class Codes: B29C 51/44 Removing or ejecting moulded articles

Abstract

A differential pressure forming machine with upper and lower mold members for forming cup-like articles in a web of thermoplastic material includes a mold assembly in which two separable die members, when in their closed position cooperatively form an article defining mold cavity which extends through one member and into the other. The two die members, when opened, are spaced from each other by a distance greater than the depth of the formed article. An endless chain of carrier members is located with one run extending between the two die members. Each carrier member has an opening smaller than the circumference of the formed article. Closing of the die members expands the carrier member opening outwardly of the periphery of the die cavity and closing of the entire mold assembly in the forming operation effects a severing of the formed article from the web. Upon subsequent opening of the die, the carrier member opening contracts, gripping the formed article to convey it clear of the mold as the next carrier member in the chain is advanced with the web into operative relationship with the mold. At a collection station a discharge member operative with the plug assist of the forming machine removes the formed and separated article from the carrier member.

Claims

1. In a differential pressure forming machine for forming cavity shaped articles in a web of thermoplastic material, said machine including web conveying means for advancing a web of thermoplastic material in step-by-step movement to a work station, mold means at said work station movable between an open and a closed position relative to said web in synchronism with the movement of said web by said web conveying means, said mold means including a first die assembly, means on said first die assembly defining an article forming cavity therein into which a portion of said web is displaced during the article forming operation, and means on said mold means for severing the article from the web upon the completion of the formation of the article;

the improvement comprising carrier means associated with said first die means and including a resiliently flexible carrier member of sheet material lying in a general plane parallel to that of said web at said work station, said carrier member having an article receiving opening therethrough of a shape similar to but smaller than the transverse cross-sectional shape of the article, first means operable when said mold means is in its open position for locating said carrier member in a ready position between said web and at least a portion of said first die assembly with the opening therein aligned with said cavity of said first die assembly, second means on said first die assembly operable upon movement of said mold means to its closed position to engage and flex said carrier member around the periphery of said opening to expand said opening to a size larger than said cross-sectional shape of said article while said mold means is closed, said second means being operable upon subsequent opening of said mold means to release said carrier member to cause said carrier member to resiliently grip the article within said opening, said first means being operable upon the arrival of said mold means at its open position for shifting said carrier member from said ready position with the article gripped therein to a discharge position clear of said mold means.

2. The invention defined in claim 1 wherein said first means comprises means linking a plurality of said carrier members into an endless chain, and drive means for successively advancing said carrier members in step-by-step movement to said ready position in synchronism with said web conveying means.

3. The invention defined in claim 1 wherein said first die assembly comprises a first die member having a recess therein defining the inner end portion of said article forming cavity, said second means having a passage therethrough cooperable with said recess to define the remaining portion of said article forming cavity when said mold means is in its closed position, means mounting said second means between said first die member and said web for movement relative to said first die member between a closed position when said mold means is in its closed position and an open position when said mold means is in its open position, said second means when in its open position being spaced from said first die member by a distance greater than the depth of said article forming cavity.

4. The invention defined in claim 3 wherein said carrier member when in its ready position is located between said first member and said second means.

5. The invention defined in claim 4 wherein said second means comprises a generally flat plate-like member, a cavity forming flange projecting from said plate-like member around the periphery of said passage at the side of said plate-like member adjacent said first member, said flange being coaxially aligned with said opening in said carrier member when said carrier member is in its ready position and being movable into said opening to displace the marginal edge of the opening in said carrier member axially and enlarge the opening to pass said flange upon movement of said mold means to its closed position.

6. The invention defined in claim 2 wherein said first die assembly comprises a first die member, a second die member located between said first die member and said web, means mounting said second die member for movement relative to said first die member between an operative position wherein said first and second die members cooperatively define said article forming cavity and an inoperative position wherein said first and second die members are spaced from each other by a distance greater than the depth of said article forming cavity, and means for causing said drive means to advance said carrier members when said first and second die member are in said inoperative position.

7. The invention defined in claim 6 wherein the carrier member, when in its ready position, is located between said first and second die members and the opening in the carrier member is expanded upon movement of said first and second members to their operative position.

8. In a differential pressure forming machine for forming cavity shaped articles in a web of thermoplastic material, said machine including web conveying means for advancing a web of thermoplastic material in step-by-step movement to a work station, and mold means at said work station cyclically operable to close and open in synchronism with the movement of said web by said web conveying means for forming articles in said web and severing the formed articles from said web upon closing;

the improvement wherein said mold means comprises a first and second separable die members located at one side of said web at said work station, said first and second die members being movable relative to each other between a closed position wherein said members define an article forming mold cavity extending through one of said members and into the other and an open position wherein the two members are spaced from each other by a distance greater than the depth of said cavity when said members are closed, an endless chain of expansible and contractible carrier means having a run extending through said work station between said die members, each of said carrier means having an expansible opening therethrough of a normal opening smaller than the width of an article formed in said mold cavity, drive means for driving said chain in step-by-step movement synchronized with movement of said web to successively advance said carrier means to a ready position between said die members with the opening in the carrier means aligned with the cavity defining portions of the die members, and expansion means for expanding the carrier means opening outwardly from the mold cavity upon movement of said die members to their closed position and for releasing the carrier means to permit the carrier means to grip the formed article upon the subsequent opening of said die members.

9. The invention defined in claim 8 wherein said carrier means comprises an annular member of resiliently flexible sheet material.

10. The invention defined in claim 8 wherein a discharge station is provided for said machine downstream from the work station to align with the incremental advance of said web and endless chain of carrier means;

said station being defined by a collection member and an article removing member operated synchronously with the closing of the mold means to engage a previously severed and removed article and remove it from said carrier means to said collection member.

11. In a differential pressure forming machine for forming cavity shaped articles in a web of thermoplastic material, said machine including web conveying means for advancing a web of thermoplastic material to a work station, and mold means at said work station cyclically operable to close and open in synchronism with the movement of said web for forming articles in said web and severing the formed articles from said web upon closing;

said mold means comprising at least first and second separable die members located at one side of said web at said work station, said first and second die members being movable relative to each other between a closed position wherein said members define an article forming mold cavity extending through one of said members and into the other and an open position wherein the two members are spaced from each other by a distance greater than the depth of said cavity when said members are closed, expansible and contractible carrier means having a movement path extending through said work station between said die members, drive means for driving said carrier means in synchronization with movement of said die members to advance said carrier means to a ready position between said die members, and means for keeping the carrier means expanded during movement of said die members to their closed position and for releasing the carrier means to permit the carrier means to grip the formed article upon the subsequent opening of said die members.

12. In a differential pressure forming machine for forming cavity-shaped articles in a web of thermoplastic material, said machine including web conveying means for advancing a web of thermoplastic material to a work station, and mold means at said work station cyclically operable to close and open in synchronism with the movement of said web for forming articles in said web and severing the formed articles from said web upon closing;

said mold means comprising at least first and second separable die members located at one side of said web at said work station, said first and second die members being movable relative to each other between a closed position wherein said members define an article forming mold cavity extending through one of said members and into the other and an open position wherein the two members are spaced from each other by a distance greater than the depth of said cavity when said members are closed, and carrier means having a movement path extending through said work station between said die members and disposed between said members when the members are closed, movable in timed relation with said mold means to convey a severed article from between said mold means to a remote location upon the opening of said mold means.

13. In a differential pressure forming machine for forming cavity-shaped articles in a web of thermoplastic material, said machine including web conveying means for advancing a web of thermoplastic material to a work station, and mold means at said work station having opposed mold parts sandwiching said web cyclically operable to close and open in synchronism with the movement of said web for forming articles in said web and severing the formed articles from said web upon relative movement of said mold parts;

one of said mold parts defining an article forming mold cavity, and carrier means, with a plurality of tandemly connected gripper carriers for gripping a part formed in the web, having a movement path extending through said work station between said opposed mold parts;

said carrier means being operated to dispose one of said gripper carriers between the mold parts in synchronism with the movement of said web conveying means such that when said carrier means is moved to convey the severed article from between said mold parts a second gripper carrier is brought along to dispose said second gripper carrier between the mold parts for cooperation with the mold parts when closed and to subsequently grip a successively formed part;

said carrier means being operable in timed relation with said mold means and web advancing means to convey a severed article from between said mold means to a remote location upon the opening of said mold means.

14. The machine defined in claim 13 wherein said carrier means comprises a series of tandemly connected gripping carriers, one of which is disposed between said mold parts, and when one carrier is moved to convey the severed article from between said mold parts a second carrier is brought along to dispose it between said mold parts, a collection chamber downstream from said mold parts to which a carrier carries a gripped article, and an article separating member operated in synchronism with said mold parts to remove a gripped article from a carrier at the collection station.

15. A method of differential pressure forming cavity shaped articles in a thermoplastic web which is fed between the parts of openable and closable forming and trimming molds, one of which has an article forming cavity formed by a pair of relatively separable, superposed die members with cavity forming side walls and wherein an article carrier having an opening therein is sandwiched between said die members and normally has article gripper means protruding radially inwardly of the cavity forming side walls in the die members comprising the steps of:

a. relatively moving the die members from separated to closed position and displacing said carrier gripper means from protruding into the die cavity so that the gripper means do not form part of the cavity, while relatively moving the molds from an open to closed position and applying a differential pressure on opposite sides of the web to cause the web to move to assume the configuration of the cavity;

b. while it is supported in the cavity, severing the molded article from the web;

c. relatively moving the parts to separate the molds and the die members and permit the gripper means to return to protruded position and grip the severed article;

d. advancing a new portion of the web between the molds while removing the portion formerly between the molds; and

e. advancing the carrier to transport the severed article to a remote location while disposing a second carrier in position between said die members.

16. The method of claim 15 wherein the carrier gripper means is displaced radially by the die member adjacent the web when it moves to closed position with the other die member, the said die member adjacent the web having a recess to accommodate the carrier when the die members are closed so that the carrier can nest therein.

17. A method of differential pressure forming cavity shaped articles in a thermoplastic web which is fed between openable and closable forming and trimming molds, one of which has an article forming cavity and wherein one of a series of tandemly connected article carriers is disposed between said molds comprising the steps of:

a. displacing said one article carrier radially from the cavity so that the carrier does not form part of the cavity, while relatively moving the molds from an open to closed position and applying a differential pressure on opposite sides of the web to cause the web to move to assume the configuration of the cavity;

b. while it is supported in the cavity, severing the molded article from the web;

c. relatively moving the molds to separate them and to permit the carrier to return to grip the severed article;

d. advancing a new portion of the web between the molds while removing the portion formerly between the molds; and

e. advancing the one carrier to transport the severed article to a remote location while disposing a second carrier in position between said molds.

18. A method of differential pressure forming cavity shaped articles in a deformable, moldable first thermoplastic web section which is fed between openable and closable forming and trimming mold members, one of which has an article forming cavity, and wherein an article carrier is sandwiched between said mold members on one side of said web and has successively disposed carrier article gripper means comprising the steps of:

a. relatively moving the mold members from separated toward closed position while said carrier is situated between the mold members and while applying a differential pressure on opposite sides of the web to cause the web to move to assume the configuration of the cavity and form a part in the web;

b. Severing the part formed the web and gripping the part with a first carrier article gripper means;

c. moving the mold members to separated position;

d. advancing the carrier to move the gripped part from between the mold members to a part collection station while advancing a second carrier article gripper means; and

e. advancing a new web section between the mold members while removing the web section formerly between the mold members.