Molding machine having yieldably restrained clamping force applying element

Claim 2

A molding machine comprising a first platen, a second platen movable towards and away from said first platen, drive means for moving said second platen towards and away from said first platen, first cylinder-and-piston means including a movable clamping element fluid actuatable for exerting a clamping force on said second platen, second cylinder-and-piston means including a movable element fluid actuatable for yieldably restraining said clamping element from moving during movement of said second platen towards said first platen, means for supplying actuating fluid to, and discharging actuating fluid from, said first cylinder-and-piston means independently of said second cylinderand-piston means, means sealingly preventing fluid communication between the cylinders of said first and second cylinder-andpiston means throughout the machine operation, control means for controlling the supply of actuating fluid to said first cylinderand-piston means and operable to prevent such flow of fluid, means responsive upon movement of said clamping element during movement of said second platen towards said first platen for causing said control means to prevent such flow of fluid, nd means for supplying actuating fluid to said second cylinder-andpiston means for causing said movable element to so yieldably restrain said clamping element.

Claim 3

A molding machine according to claim 1, wherein the yieldable restraining force applied to said clamping element by said movable element is substantially lower than the clamping force applied by said clamping element.

Claim 4

A molding machine according to claim 2, wherein said second cylinder-and-piston means is on the opposite side of said first cylinder-and-piston means from said platens, and said movable element engages said clamping element.

Claim 5

A molding machine according to claim 3, wherein the clamping element of said first cylinder-and-piston means is of larger diameter than the movable element of said second cylinder-and-piston means.

Claim 6

A molding machine according to claim 2, further comprising a toggle linkage connected to said drive means and said second platen to cause said drive means to drive said second platen through said toggle linkage means, and said clamping element being connected to said toggle linkage to apply the clamping force therethrough.

Claim 7

A molding machine comprising a first platen, a clamping platen spaced from said first platen, a movable platen positioned and movable between said first and clamping platens, a toggle linkage actuatable for moving said movable platen towards and away from said first platen, said toggle linkage including link means pivotally connected to said movable platen, link actuating means connected to said link means for moving said link means between open and closed platen positions, first cylinder-and-piston means including a movable clamping element connected to said link means and fluid actuatable for exerting a clamping force on said movable platen through said link means, second cylinder-and-piston means including a movable element fluid-caused to yieldably restrain said clamping element from moving during movement of said link means to their closed platen positions, control means for controlling the supply of fluid to said first cylinder-and-piston means and operable to prevent such flow, and means responsive to movement of said clamping element during movement of said link means to their said closed platen positions to cause said control means to prevent such flow.

Claim 8

A molding machine comprising a first platen, a clamping platen spaced from said first platen, a movable platen positioned and movable between said first and clamping platens, a toggle linkage actuatable for moving said movable platen towards and away from said first platen, said toggle linkage including link means pivotally connected to said movable platen, link actuating means connected to said link means for moving said link means between open and closed platen positions, first cylinder-and-piston means including a movable clamping element connected to said link means and fluid actuatable for exerting a clamping force on said movable platen through said link means, second cylinder-and-piston means including a movable element fluid-caused to yieldably restrain said clamping element from moving during movement of said link means to their closed platen positions, control means for controlling the supply of fluid to said first cylinder-and-piston means and operable to prevent such flow, and means responsive to movement of said clamping element during movement of said link means to their said closed platen positions to cause said control means to prevent such flow.

Claim 9

A molding machine according to claim 6, wherein the area of said clamping element on which the actuating fluid acts is substantially larger than the fluid engaging area of said movable element of said second cylinder-and-piston meanS.

Claim 10

A molding machine comprising a first platen, a clamping platen spaced from said first platen, a movable platen positioned and movable between said first and clamping platens, a toggle linkage actuatable for moving said movable platen towards and away from said first platen, said toggle linkage including link means pivotally connected to said movable platen, link actuating means connected to said link means for moving said link means between open and closed platen positions, first cylinder-and-piston means including a movable clamping element connected to said link means and fluid actuatable for exerting a clamping force on said movable platen through said link means, and second cylinder-and-piston means including a movable element fluid-caused to yieldably restrain said clamping element from moving during movement of said link means to their closed platen positions, the movable elements of said first and second cylinder-and-piston means being the pistons thereof, and the piston of said second cylinder-and-piston means being provided with a rod for engaging the piston of said first cylinder-and-piston means.

Claim 11

A molding machine comprising a first platen, a clamping platen spaced from said first platen, a movable platen positioned and movable between said first and clamping platens, a toggle linkage actuatable for moving said movable platen towards and away from said first platen, said toggle linkage including link means pivotally connected to said movable platen, link actuating means connected to said link means for moving said link means between open and closed platen positions, first cylinder-and-piston means including a movable clamping element connected to said link means and fluid actuatable for exerting a clamping force on said movable platen through said link means, and second cylinder-and-piston means including a movable element fluid-caused to yieldably restrain said clamping element from moving during movement of said link means to their closed platen positions, the movable elements of said first and second cylinder-and-piston means being the pistons thereof, and the piston of said second cylinder-and-piston means being provided with a rod for engaging the piston of said first cylinder-and-piston means.

Claim 12

A molding machine according to claim 8, wherein the diameter of the piston of said second cylinder-and-piston means is substantially smaller than the diameter of the piston of said first cylinder-and-piston means.

Claim 13

A molding machine comprising a first platen, a clamping platen spaced from said first platen, a movable platen positioned and movable between said first and clamping platens, a toggle linkage actuatable for moving said movable platen relative to said first platen, said toggle linkage including a plurality of links pivotally interconnected and pivotally connected to said movable platen, link actuating means connected to said links for moving said links between closed platen positions wherein said links are generally aligned and open platen positions wherein said links extend to one side of their said closed platen positions, said clamping platen containing a cylinder, a first piston in said cylinder and connected to said links for exerting a clamping force on said movable platen through said links, means for supplying pressurized fluid to said clamping platen cylinder for causing said first piston to apply said clamping force, control means for controlling flow of fluid to said clamping platen cylinder and operable to prevent such flow, second cylinder-and-piston means including a second piston fluid actuatable for yieldably restraining movement of said first piston during movement of said link means to their said closed platen positions, means for supplying fluid to the cylinder of said second cylinder-and-piston means to cause said second piston to so yieldably restrain such movement of said first piston, and means responsive to movement of said first piston caused by movement of said links to their closed platen positions for operating said control means to prevent flow of fluid to said clamping platen cylinder.

Claim 14

A molding machine comprising a first platen, a clamping platen spaced from said first platen, a movable platen positioned and movable between said first and clamping platens, a toggle linkage actuatable for moving said movable platen relative to said first platen, said toggle linkage including a plurality of links pivotally interconnected and pivotally connected to said movable platen, link actuating means connected to said links for moving said links between closed platen positions wherein said links are generally aligned and open platen positions wherein said links extend to one side of their said closed platen positions, said clamping platen containing a cylinder, a first piston in said cylinder and connected to said links for exerting a clamping force on said movable platen through said links, means for supplying pressurized fluid to said clamping platen cylinder for causing said first piston to apply said clamping force, control means for controlling flow of fluid to said clamping platen cylinder and operable to prevent such flow, second cylinder-and-piston means including a second piston fluid actuatable for yieldably restraining movement of said first piston during movement of said link means to their said closed platen positions, means for supplying fluid to the cylinder of said second cylinder-and-piston means to cause said second piston to so yieldably restrain such movement of said first piston, and means responsive to movement of said first piston caused by movement of said links to their closed platen positions for operating said control means to prevent flow of fluid to said clamping platen cylinder.

Claim 15

A molding machine according to claim 10, wherein the area of said second piston on which the fluid acts is substantially smaller than the area of said first piston on which the fluid acts.

Claim 16

A molding machine according to claim 11, wherein said second piston is provided with a rod extending into said clamping platen cylinder to engage said first piston.

Claim 17

A molding machine according to claim 12, wherein said rod is of a length to permit fluid supplied to the cylinder of said second cylinder-and-piston means to cause said second piston to yieldably restrain said first piston in spaced relationship to the ends of said clamping platen cylinder.