Strap tensioning and sealing tool

Claim 2

In a pneumatically operable strapping tool for tensioning a loop of thermoplastic strapping having overlapping end portions about an article and thereafter effecting interfacial fusion of said end portions to provide a joint, an air-operated motor having an air supply port, an air supply line leading to said port, a fixed pressure jaw and a cooperating displaceable vibratory pressure jaw for engaging said overlapping end portions to produce interfacial friction therebetween and thus create said joint, said vibratory jaw being shiftable bodily between an advanced strap-engaging position and a retracted strap-releasing position, an eccentric driving connection between said motor and movable jaw for effecting continuous vibration of the latter in any shifted position thereof, spring means yieldingly biasing said vibratory jaw toward its retracted position, an air-operated ram connected to the vibratory movable jaw and effective when supplied with air to shift the latter to its advanced strapengaging position, a pressure-responsive plunger valve operatively connected to said air supply line and ram, said plunger valve including a plunger which is effective in a retracted position to supply air to said ram at a predetermined rate and in an advanced position to discontinue such supply of air, means normally maintaining said plunger in its retracted position, and a pressure chamber operatively connected to said supply port, said plunger being responsive to the pressure of air in said pressure chamber whereby, when the back-up pressure of air at said supply port reaches a predetermined maximum, the plunger will be shifted to its advanced position.

Claim 3

In a pneumatically operable strapping tool, the combination set forth in claim 1, including additionally shiftable valve means interposed in said air supply line and normally effective in a first position to restrict the flow of air through said supply line, and in a second position to increase the flow of air through said supply line, and wherein the plunger of said plunger valve is effective in its advanced position to shift said shiftable valve means from its first position to its second position.

Claim 4

In a pneumatically operable strapping tool for tensioning a loop of fusible strapping having overlapping end portions about an article and thereafter effecting interfacial fusion of said portions to provide a joint, a feed wheel and a cooperating gripper anvil member engageable with said end portions to produce relative sliding movement therebetween in a loop tensioning direction, a fixed pressure jaw and a cooperating vibratory pressure jaw engageable with said end portions to produce multidirectional frictional sliding movement therebetween with consequent interfacial fusion, an air motor having an air inlet port, a first power train extending between said motor and vibratory pressure jaw and effective to produce vibratory movements of the latter, a second power train including a normally engaged clutch extending between an element of the first power train and thE feed wheel and effective to produce rotation of the latter in a tensioning direction, a movable air-operated ram effective when supplied with air to force said vibratory pressure jaw into sealing cooperation with the fixed pressure jaw and to disengage said clutch, a manually operable main valve for supplying air to said inlet port, a pneumatically operable plunger valve responsive to the incidence of back-up pressure of air at said inlet port for supplying air to the ram, and means automatically effective upon disengagement of said clutch for preventing reverse rotation of the feed wheel.

Claim 5

In a pneumatically operable strapping tool for tensioning a loop of fusible strapping having overlapping end portions about an article and thereafter effecting interfacial fusion of said portions to provide a joint, a feed wheel and a cooperating gripper anvil member engageable with said end portions to produce relative sliding movement therebetween in a loop tensioning direction, a fixed pressure jaw and a cooperating vibratory pressure jaw engageable with said end portions to produce multidirectional frictional sliding movement therebetween with consequent interfacial fusion, an air motor having an air inlet port, a first power train extending between said motor and vibratory pressure jaw and effective to produce vibratory movements of the latter, a second power train including a normally engaged clutch extending between an element of the first power train and thE feed wheel and effective to produce rotation of the latter in a tensioning direction, a movable air-operated ram effective when supplied with air to force said vibratory pressure jaw into sealing cooperation with the fixed pressure jaw and to disengage said clutch, a manually operable main valve for supplying air to said inlet port, a pneumatically operable plunger valve responsive to the incidence of back-up pressure of air at said inlet port for supplying air to the ram, and means automatically effective upon disengagement of said clutch for preventing reverse rotation of the feed wheel.

Claim 6

In a pneumatically operable strapping tool, the combination set forth in claim 3 wherein said gripper anvil member is spring biased into effective cooperation with the feed wheel, the strapping tool further includes releasable latch means normally maintaining said gripper anvil member in a retracted position, and the main valve is effective upon operation thereof to release said latch means.

Claim 7

In a pneumatically operable strapping tool, the combination set forth in claim 4 including, additionally, a rotary crank member effectively interposed between and engageable with the ram and movable pressure jaw for translating movement of the ram into movement of the vibratory pressure jaw, and wherein said latch means includes a latch element movably mounted on the gripper anvil member, and a latch finger on said crank member against which said latch element normally bears to maintain the gripper anvil member out of effective cooperation with the feed wheel.

Claim 8

In a pneumatically operable strapping tool for tensioning a loop of thermoplastic strapping having overlapping end portions about an article and thereafter effecting interfacial fusion of said end portions, an air-operated motor having an air supply port, a feed wheel engageable with the strapping for tensioning said loop, a power train including a normally engaged clutch connecting the motor to the feed wheel in driving relationship, a fixed pressure jaw and a cooperating bodily displaceable vibratory pressure jaw for engaging said overlapping end portions to produce interfacial friction therebetween and consequent fusion, said displaceable pressure jaw being movable between a raised inoperative strap-releasing position and a lowered strap engaging and sealing position, a second power train connecting the motor to the vibratory pressure jaw and effective to cause vibration of the latter in any position thereof, a normally closed manually operable main air supply valve effective when actuated to supply air to said air supply port to rotate the feed wheel and effect vibration of said shiftable vibratory pressure jaw, a sealing cylinder having a ram and effective when supplied with air to project said ram, said ram, upon projection thereof, being effective to move said vibratory jaw to its lowered sealing position and to disengage said normally engaged clutch, a pneumatically operable plunger valve responsive to the incidence of back-up air pressure at said supply port and effective upon actuation thereof to supply air to said sealing cylinder, and a pneumatically operable two-position speed valve interposed between the main valve and the air supply port and operable under the control of said plunger valve, said speed valve being effective in its normal position to conduct air from the main valve to the air supply port at a predetermined rate for feed wheel driving purposes, and in another position to supply such air at an increased rate for strap-sealing purposes.

Claim 9

In a pneumatically operable strapping tool for tensioning a loop of thermoplastic strapping having overlapping end portions about an article and thereafter effecting interfacial fusion of said end portions, an air-operated motor having an air supply port, a feed wheel engageable with the strapping for tensioning said loop, a power train including a normally engaged clutch connecting the motor to the feed wheel in driving relationship, a fixed pressure jaw and a cooperating bodily displaceable vibratory pressure jaw for engaging said overlapping end portions to produce interfacial friction therebetween and consequent fusion, said displaceable pressure jaw being movable between a raised inoperative strap-releasing position and a lowered strap engaging and sealing position, a second power train connecting the motor to the vibratory pressure jaw and effective to cause vibration of the latter in any position thereof, a normally closed manually operable main air supply valve effective when actuated to supply air to said air supply port to rotate the feed wheel and effect vibration of said shiftable vibratory pressure jaw, a sealing cylinder having a ram and effective when supplied with air to project said ram, said ram, upon projection thereof, being effective to move said vibratory jaw to its lowered sealing position and to disengage said normally engaged clutch, a pneumatically operable plunger valve responsive to the incidence of back-up air pressure at said supply port and effective upon actuation thereof to supply air to said sealing cylinder, and a pneumatically operable two-position speed valve interposed between the main valve and the air supply port and operable under the control of said plunger valve, said speed valve being effective in its normal position to conduct air from the main valve to the air supply port at a predetermined rate for feed wheel driving purposes, and in another position to supply such air at an increased rate for strap-sealing purposes.

Claim 10

In a pneumatically operable strapping tool, the combination set forth in claim 9 wherein said speed valve is provided with a manually adjustable orifice for regulating the rate of flow of air to said air supply port when the valve is in its normal position.

Claim 11

In a pneumatically operable strapping tool, the combination set forth in claim 6 including, additionally, releasable latch means effective upon actuation of said main valve to maintain the same actuated, a latch release cylinder having a normally retracted latch tripping plunger adapted upon projection thereof to engage the latch means and disable the same, said plunger valve being effective upon actuation thereof to supply air to said latch release cylinder to project said latch tripping plunger.

Claim 12

In a pneumatically operable strapping tool, the combination set forth in claim 8 and including, additionally, time delay means for regulating the flow of air from the plunger valve to the latch release cylinder to thus determine the length of time the latch means remains effective.

Claim 13

In a pneumatically operable strapping tool, the combination set forth in claim 9, wherein said time delay means includes an air accumulation chamber interposed between the plunger valve and latch release cylinder and effective when a predetermined air pressure has been attained therein to actuate the latch release cylinder.

Claim 14

In a pneumatically operable strapping tool, the combination set forth in claim 10, wherein said time delay means further includes a timing valve having an adjustable orifice interposed between the plunger valve and air accumulation chamber for regulating the rate of flow of air from the plunger valve into the air accumulation chamber.

Claim 15

In a pneumatically operable strapping tool, the combination set forth in claim 9, wherein said plunger valve embodies a valve cylinder and an enlarged pressure chamber at one end thereof and in communication with said air supply port for the motor, said pressure chamber defining an internal sealing annulus, a flexible diaphragm extending across said chamber and having an effective area greater than the overall area of the sealing annulus, an axially shiftable valve spool slidable in said valve cylinder between a normal retracted position wherein it bears yieldingly against the diaphragm and urges the latter against the sealing annulus so that air pressure in the chamber is effective against only the central region of the diaphragm, and an extended position wherein air pressure in the chamber is effective against the entire diaphragm area, said valve cylinder being provided with an air inlet port connected to a source of air, and an air outlet port connected to said sealing cylinder, said valve spool being effective in its retracted position to prevent communication between said air inlet port and said air outlet port, and in its extended position to establish communication between said latter ports.

Claim 16

In a pneumatically operable strapping tool, the combination set forth in claim 12, wherein said valve cylinder of the plunger valve is provided with a second air outlet port which is connected to the speed valve, and wherein the valve spool is effective in its retracted position to prevent communication between said air inlet port and said second air outlet port, and in its extended position to establish communication between said latter ports.

Claim 17

In a pneumatically operable strapping tool, the combination set forth in claim 12, wherein said valve spool is yieldingly biased against said diaphragm by means of a compression spring, the combination including, additionally, a regulating screw for adjusting the force exerted by the spring upon the plunger whereby the plunger valve may be made responsive to varying back-up pressures at said air supply port.

Claim 18

In a pneumatically operable strapping tool, the combination set forth in claim 14 including, additionally, a restriction interposed between the air supply port and said pressure chamber and serving to prevent back-up surge pressure at said latter port incident to motor starting-up operations from prematurely actuating said sealing valve.