Apparatus for forming plastic articles from sheet materials

Claim 2

Apparatus for forming hollow plastic articles from sheet material, said apparatus comprising: a supporting frame structure, first and second cooperable forming members each of which include a die face of predetermined contour, said forming members being movably mounted to said supporting frame to permit relative reciprocal movement therebetween in two substantially perpendicular directions, the first of said directions being to bring said die faces together and apart, at least one plug assist means comprising a rod having a rounded ball section connected thereon, said rod fixedly mounted to one of said forming members and disposed from the die face of that forming member in the second of said directions of reciprocal movement, said rounded ball section of said rod defining an engaging surface for contact along being substantially smaller than the total surface of said sheet material, means for positioning plastic sheet material adjacent each of said die faces, means for urging the forming members to one extreme of the reciprocal movement in the second direction and aligning the at least one rod opposite the die face of the other forming member, means for urging the forming members and attached die faces and said rod attached thereto together and apart through the reciprocal movement in said first direction thereby urging the sheet material against at least one die face by means of said engaging surface of said rod, means for releasably securing the sheet material to the die faces, means for urging forming members to the other extreme of reciprocal movement in the second direction and aligning the opposed die faces and means for bringing the die faces and sheet material together whereby a hollow plastic article is formed.

Claim 3

The apparatus of claim 1 wherein each of said forming members include a rod having a rounded ball section connected thereon, and wherein each rod displaces sheet material in opposite directions toward the die face of the other forming member.

Claim 4

Apparatus for thermoforming hollow plastic articles from plastic sheet material, said apparatus comprising: A first die member having a die face of predetermined contour and a first plug assist means comprising a rod spaced therefrom, said rod having a rounded ball section thereon; a second die member having a die face of predetermined contour and a second plug assist means comprising a rod spaced therefrom, said rod having a rounded ball section thereon; said first rod being fixedly attached to said second die member and said second rod being fixedly attached to said first die member, said first and second rods defining upon said rounded ball section of each an engaging surface for contact along preselected points of the plastic sheet material, said engaging surface of each rod being substantially smaller than their corresponding surface of said plastic material; frame means for positioning first and second sheets of heated plastic material adjacent each of said die members; a first drive means for moving one of said die members relative to the other between a first position in which said rods are each aligned with a predetermined portion of the die face of the other die member and in a second position in which said die faces are aligned with one another; a second drive means for relative movement of said die members toward and away from one another; pressure differential means associated with each said die face for pulling sheet material into contact with the die face; and control means for causing said first drive means to move said die members to said first position, for causing said second drive means to move said die members toward one another so that said rounded ball sections of said rods displace said heated plastic sheets toward said die faces, and for causing said pressure means to pull said plastic sheets into contact with said die faces, said control means thereafter causing said second drive means to move said die members away from one another, causing said first drive means to move said die members to said second position, causing said die members to again be moved toward one another so that said die faces are brought into abutting engagement, and causing said pressure differential means to maintain said plastic sheets in contact with said die faces until said hollow article is formed by bringing said die faces into abutting relationship with one another, said control means causing said second drive means to move said die members away from one another after said die faces have been in abutting relationship to release said hollow article thus formed.

Claim 5

Apparatus for thermoforming hollow plastic articles from plastic sheet material, said apparatus comprising: A first die member having a die face of predetermined contour and a first plug assist means comprising a rod spaced therefrom, said rod having a rounded ball section thereon; a second die member having a die face of predetermined contour and a second plug assist means comprising a rod spaced therefrom, said rod having a rounded ball section thereon; said first rod being fixedly attached to said second die member and said second rod being fixedly attached to said first die member, said first and second rods defining upon said rounded ball section of each an engaging surface for contact along preselected points of the plastic sheet material, said engaging surface of each rod being substantially smaller than their corresponding surface of said plastic material; frame means for positioning first and second sheets of heated plastic material adjacent each of said die members; a first drive means for moving one of said die members relative to the other between a first position in which said rods are each aligned with a predetermined portion of the die face of the other die member and in a second position in which said die faces are aligned with one another; a second drive means for relative movement of said die members toward and away from one another; pressure differential means associated with each said die face for pulling sheet material into contact with the die face; and control means for causing said first drive means to move said die members to said first position, for causing said second drive means to move said die members toward one another so that said rounded ball sections of said rods displace said heated plastic sheets toward said die faces, and for causing said pressure means to pull said plastic sheets into contact with said die faces, said control means thereafter causing said second drive means to move said die members away from one another, causing said first drive means to move said die members to said second position, causing said die members to again be moved toward one another so that said die faces are brought into abutting engagement, and causing said pressure differential means to maintain said plastic sheets in contact with said die faces until said hollow article is formed by bringing said die faces into abutting relationship with one another, said control means causing said second drive means to move said die members away from one another after said die faces have been in abutting relationship to release said hollow article thus formed.

Claim 6

Apparatus for forming hollow plastic articles from sheet material, said apparatus comprising: first and second cooperable forming members at opposite sides of sheet material, each of said forming members including a die face of predetermined contour with at least one of said forming members also including attached to the other of said forming members an assist means comprising a rod having a rounded ball section connected thereon, said rod defining upon said rounded section an engaging surface for contact along preselected points of the sheet material, said engaging surface being substantially smaller than the total surface of said sheet material; first drive means for causing relative movement between said forming members in a first direction whereby in one position one of said die faces is aligned with said rod attached to the other of said forming members with said sheet material therebetween and in a second position said die faces are aligned with one another with said sheet material therebetween; and second drive means for causing relative movement between said forming members in a second direction in one position of which said forming means are spaced from said sheet means and in a second position of which said forming means engage said sheet material.

Claim 7

Apparatus for forming hollow plastic articles from sheet material, said apparatus comprising: first and second cooperable forming members at opposite sides of sheet material, each of said forming members including a die face of predetermined contour with at least one of said forming members also including attached to the other of said forming members an assist means comprising a rod having a rounded ball section connected thereon, said rod defining upon said rounded section an engaging surface for contact along preselected points of the sheet material, said engaging surface being substantially smaller than the total surface of said sheet material; first drive means for causing relative movement between said forming members in a first direction whereby in one position one of said die faces is aligned with said rod attached to the other of said forming members with said sheet material therebetween and in a second position said die faces are aligned with one another with said sheet material therebetween; and second drive means for causing relative movement between said forming members in a second direction in one position of which said forming means are spaced from said sheet means and in a second position of which said forming means engage said sheet material.