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US 4,341,137 AGranted
Material forming apparatus
AssigneeThe Warner & Swasey Company
InventorsPaul A. Leitch, Thomas W. Shinn
Life of this patent
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AssigneeThe Warner & Swasey Company
InventorsPaul A. Leitch, Thomas W. Shinn
Estimating the term…
A pneumatic press assembly 10 uses air pressure to power a piston 70 in a cylinder 52 through a power stroke. Springs 76, 78, 80, 82, 84, and 86 oppose the motion of the piston 70. A set of return springs (76 and 78) is effective over the entire stroke of the piston. The return springs are compactly mounted within the cylinder 52 between the bottom of the piston 70 and a shoulder 56 which extends radially inwardly from the cylinder wall. The shoulder also cooperates with a central portion 110 of the piston 70 to prevent rotation of the piston. A second set of springs (80, 82, 84, and 86) is effective only when the piston 70 is within a predetermined distance from the bottom of the power stroke. The second set of springs 80, 82, 84 and 86 is disposed between the bottom 230 of the cylinder 52 and a preload member 234. When the piston 70 approaches the bottom of its stroke, it contacts the preload member 234 which in turn compresses the springs 80, 82, 84, and 86 bringing the piston to a halt. These springs then expand, accelerating the piston 70 to a relatively high speed during an initial portion of the return stroke. During the initial portion of the return stroke, air displaced by the piston is permitted to escape freely from the cylinder. During a subsequent portion of the return stroke, the air displaced by the piston is forced through a restricted flow path to dissipate the kinetic energy of the piston. In addition, a spring loaded bumper is provided which contacts the piston at the end of the return stroke to cushion impact between the piston and the cylinder head.
An apparatus for use in forming material with a tool, said apparatus comprising housing means for defining a chamber, a piston adapted to be connected with the tool, said piston being axially movable within said chamber, means for introducing fluid under pressure into said chamber to cause said piston to move in said chamber through a power stroke in a first direction to thereby effect movement of the tool relative to the material, return means for moving said piston through a return stroke in a second direction to retract the tool from the workpiece, and dissipating means for dissipating kinetic energy of said piston as said piston moves through its return stroke in said second direction, said dissipating means including means for providing a relatively unrestricted flow path for conducting a flow of fluid displaced from the chamber by said piston at a first rate during a first portion of the return stroke and for providing a relatively restricted flow path for conducting a flow of fluid displaced from the chamber by said piston at a second rate which is less than the first rate during a second portion of the return stroke.
An apparatus for use in forming material with a tool, said apparatus comprising a chamber, a piston adapted to be connected with the tool, said piston being axially movable within said chamber, said piston having a generally cylindrical head portion with surface means defining a circular end face which is exposed to fluid pressure during a power stroke, a generally cylindrical rod portion adapted to be connected with the tool, said rod portion of said piston having a smaller diameter than said head portion of said piston, and a cylindrical intermediate portion coaxial with and disposed between said head and rod portions, said intermediate portion having a diameter which is larger than the diameter of said rod portion and smaller than the diameter of said head portion, said chamber having a radially inwardly projecting section disposed proximate said intermediate portion of said piston, means extending between said intermediate portion of said piston and said section of said chamber for holding said piston against rotary motion relative to said chamber, means for introducing fluid under pressure into said chamber to cause said piston to move in said chamber through a power stroke in a first direction to thereby effect movement of the tool relative to the material, return means for moving said piston through a return stroke in a second direction to retract the tool from the workpiece, said return means including first spring means for urging said piston in the second direction, said head portion of said piston including surface means defining a plurality of axially extending recesses, said radially inwardly projecting section of said chamber including surface means defining a plurality of recesses aligned with said recesses in said head portion of said piston, said first spring means including a plurality of helical coil springs, one end portion of each of said springs being received in one of said recesses in said head portion of said piston and the opposite end portion of each of said springs being received in one of said recesses in said section of said chamber, said recesses in said head portion of said piston being disposed radially outwardly of said intermediate portion of said piston, and dissipating means for dissipating kinetic energy of said piston as said piston moves through its return stroke in said second direction, said dissipating means including means for providing a relatively unrestricted flow path for fluid displaced by said piston during a first portion of the return stroke and for providing a relatively restricted flow path for fluid displaced by said piston during a second portion of the return stroke.
An apparatus for use in forming material with a tool, said apparatus comprising a cylindrical chamber having at least one end surface, a piston adapted to be connected with the tool, said piston being axially movable in said chamber, said piston having a head portion with an end face which is exposed to fluid pressure during the power stroke, a rod portion adapted to be connected with the tool, and an intermediate portion disposed between said rod and head portions, said intermediate portion having a cross sectional area which is greater than the cross sectional area of said rod portion and less than the cross sectional area of said head portion, means for introducing fluid under pressure into said cylinder to cause said piston to move in said chamber in a first direction through a power stroke and return means for moving said piston in said chamber in a second direction through a return stroke, said return means including first spring means effective during the entire return stroke of said piston to urge said piston in the second direction and second spring means effective to urge said piston in said second direction only during the final portion of the power stroke and the initial portion of the return stroke, said first spring means being effective to continuously apply a force in the second direction to said head portion of said piston, said second spring means being effective to apply a force in the second direction to said intermediate portion of said piston during the final portion of the power stroke and during the initial portion of the return stroke.
An apparatus for use in forming material with a tool, said apparatus comprising having means for defining a cylindrical chamber having at least one end surface, a piston adapted to be connected with the tool, said piston being axially movable in said chamber, said piston including a cylindrical head portion with a circular end face which is exposed to fluid pressure during the power stroke, a rod portion adapted to be connected with the tool, and an intermediate portion disposed between said rod and head portions in a coaxial relationship with said rod and head portions, said intermediate portion having a cross sectional area which is greater than the cross sectional area of said rod portion and less than the cross sectional area of said head portion, means for introducing fluid under pressure into said chamber to cause said piston to move in said chamber in a first direction through a power stroke and return means for moving said piston in said chamber in a second direction through a return stroke, said return means including first spring means disposed within said housing means for applying force in the second direction to said head portion of said piston at a location radially outwardly of said intermediate portion of said piston, and second spring means disposed within said housing means for applying force in the second direction to said intermediate portion of said piston.
An apparatus for use in forming material with a tool, said apparatus comprising housing means for defining a chamber, a piston adapted to be connected with the tool, said piston being axially movable in said chamber through a power stroke in a first direction and being axially movable in said chamber through a return stroke in a second direction, a source of fluid under pressure, tank means for holding fluid under pressure, means for conducting a flow of fluid from said source of fluid to said tank means to accumulate fluid under pressure in said tank means, means for conducting a flow of fluid from said tank means to said chamber along a first fluid flow path and for conducting a flow of fluid from said source of fluid to said chamber along a second fluid flow path which is separate from said tank means upon initiation of a power stroke to supply said chamber with fluid conducted from said tank means and with fluid conducted from said source of fluid independently of said tank means upon initiation of a power stroke.
Dependencies are inferred from the claim text.