Rotary Bag Machine With Skirtless Seal

Abstract

A machine and method for making bags is described and includes a web traveling from an input section to a rotary drum, to an output section. The rotary drum includes at least one seal bar, having a single sealing zone, and an weakening zone disposed within the single sealing zone. The single sealing zone may be a heated perforator, includes a heating wire. The heating wire may be an NiCr wire and make intermittent contact with the web and be disposed in an insert. The weakening zone may create a line of weakness that is uniform or varies in intensity. The sealing zone may include temperature zones, cartridge heaters, cooling air, or heated air, or a source of ultrasonic, microwave or radiative energy.

1 . A bag machine, comprising: 
 an input section;    a rotary drum, disposed to receive a web from the input section, wherein the rotary drum includes at least one seal bar; and    an output section, disposed to receive the web from the rotary drum;    wherein the at least one seal bar includes a first sealing zone that forms a single seal, and further includes a weakening zone within the first sealing zone, that forms a weakened zone within the single seal.    
     
     
         2 . The bag machine of  claim 1 , wherein the weakening zone is a heated perforator.  
     
     
         3 . The bag machine of  claim 2 , wherein the heated perforator includes at least one of a heating wire, a flat thin film heater and a shaped thin film heater.  
     
     
         4 . The bag machine of  claim 3 , further comprising a source of power at an adjustable voltage connected to the heating wire.  
     
     
         5 . The bag machine of  claim 4 , further comprising a feedback loop connected to the heating wire and the source of power.  
     
     
         6 . The bag machine of  claim 3 , further comprising a source of pulsed power connected to the heating wire.  
     
     
         7 . The bag machine of  claim 3 , wherein the heating wire is disposed to be able to make intermittent contact with the web.  
     
     
         8 . The bag machine of  claim 3 , wherein the heating wire is at least one of a nickel chromium resistance wire and a thin film heater.  
     
     
         9 . The bag machine of  claim 3 , wherein the sealing zone is comprised of a insert having a resistance heater.  
     
     
         10 . The bag machine of  claim 9 , wherein the sealing zone includes a first face disposed to contact the web and is further comprised of a double sided tape having a first side disposed to be affixed to a supporting structure, a resistance heater affixed to a second side of the double sided tape, a heat conductive layer, affixed to the resistance heater, an releasing and electrical insulating layer affixed to the heat conductive layer, and a wire heater affixed to the releasing and electrical insulating layer, wherein the wire heater is disposed to be in thermal contact with the web.  
     
     
         11 . The bag machine of  claim 1 , wherein the first sealing zone and the weakening zone include a wire, a releasing layer, and a heat insulating layer, wherein the releasing layer is between the wire and the heat insulating layer, and the wire is disposed to comes into contact with the web.  
     
     
         12 . The bag machine of  claim 1 , wherein the weakening zone is disposed to create a line of weakness that varies in intensity.  
     
     
         13 . The bag machine of  claim 1 , wherein the weakening zone is a separating zone.  
     
     
         14 . The bag machine of  claim 1 , wherein the weakening zone includes a toothed blade.  
     
     
         15 . The bag machine of  claim 3 , further comprising an adjustable source of power connected to the heating wire.  
     
     
         16 . The bag machine of  claim 1 , wherein the single seal extends at most 0.25 inches in the machine direction.  
     
     
         17 . The bag machine of  claim 1 , wherein the single seal extends at most 0.125 inches in the machine direction.  
     
     
         18 . The bag machine of  claim 1  wherein the first sealing zone extends a first portion of a distance across the web, and a second sealing zones extends across a second portion of the distance across web, wherein the second sealing zone forms two parallel seals and a weakened area disposed between the two parallel seals.  
     
     
         19 . The bag machine of  claim 1  wherein the first sealing zone includes at least two parallel sealing subzones, extending in the cross machine direction, and the perforating zone is disposed between the at least two parallel sealing subzones.  
     
     
         20 . The bag machine of  claim 1 , wherein the sealing zone includes a support bar, an insert mounted on the support bar, a releaser mounted on the insert, and a wire mounted over the releaser disposed to contact the web.  
     
     
         21 . The bag machine of  claim 20 , wherein the support bar is an aluminum block heater.  
     
     
         22 . The bag machine of  claim 21 , wherein the releasing layer is comprised of at least one of teflon, kapton, and rulon.  
     
     
         23 . The bag machine of  claim 22 , wherein the insert is has a plurality of holes disposed along a line in the cross direction.  
     
     
         24 . The bag machine of  claim 23 , wherein the heating wire is comprised of about 80% nickel and about 20% chromium, and has a resistance of about 4 ohms/ft, and is mounted in and between the plurality of holes.  
     
     
         25 . The bag machine of  claim 1 , wherein the sealing zone includes a wire mounted on a support bar and disposed to contact the web.  
     
     
         26 . The bag machine of  claim 1 , wherein the sealing zone includes a support bar, a thin film heater mounted on the support bar, and a wire heater mounted on the thin film heater such that the wire heater is disposed to contact the web.  
     
     
         27 . A method of making bags comprising: 
 receiving a web;    forming a single seal on the web using a seal bar on a rotary drum;    forming a weakened area within the single seal for at least a portion of the time the first seal is being formed.    
     
     
         28 . The method of  claim 27 , wherein forming a weakened area includes forming a perforation.  
     
     
         29 . The method of  claim 28 , wherein forming a perforation includes heating at least one of a wire and a thin web.  
     
     
         30 . The method of  claim 29 , further applying power to the wire using an adjustable voltage.  
     
     
         31 . The method of  claim 30 , further comprising monitoring a signal indicative of heat in the wire and controlling power applied to the wire in response to the signal.  
     
     
         32 . The method of  claim 31 , further comprising pulsing the power.  
     
     
         33 . The method of  claim 27 , wherein forming a weakened area includes forming a line of weakness that varies in intensity.  
     
     
         34 . The method of  claim 27 , wherein forming a weakened area includes separating adjoining bags.  
     
     
         35 . The method of  claim 28 , wherein forming a perforation includes contacting the web with a toothed blade.  
     
     
         36 . The method of  claim 27 , wherein the single seal extends at most 0.25 inches in the machine direction.  
     
     
         37 . The method of  claim 27 , wherein the single seal extends at most 0.125 inches in the machine direction.  
     
     
         38 . The method of  claim 36 , further comprising, independently controlling a plurality of temperature zones when forming the single seal.  
     
     
         39 . The method of  claim 28 , wherein forming the single seal includes applying power to a resistance heater.  
     
     
         40 . The method bag machine of  claim 39 , wherein forming the single seal and forming the weakened area include applying power to a sealing/heating assembly comprised of a first face moved into contact with the web, and further comprised of a double sided tape, a heat conductive layer, and an insulative layer, wherein the insulative layer is between the first face and the heat conductive layer, the heat conductive layer is between the insulative layer and the resistance heater, and the resistance heater is between the heat conductive layer and the double sided tape.  
     
     
         41 . The method bag machine of  claim 27 , wherein forming the single seal and forming the weakened area includes applying power to a sealing/heating assembly comprised of a wire, a releasing layer, and a heat insulating layer, wherein the releasing layer is between the heat insulating layer and the wire, and further includes moving the wire into contact with the web.  
     
     
         42 . The method of  claim 28 , wherein forming a single seal includes bringing at least two parallel sealing subzones into thermal contact with the web, and forming the weakened area includes bringing a weakening zone disposed between the parallel sealing subzones into thermal contact with the web.  
     
     
         43 . The method of  claim 28  wherein forming a single seal includes forming a first seal portion that extends a first portion of a distance across the web, and forming a second seal portion that extends across a second portion of the distance across the web.  
     
     
         44 . The method of  claim 28  wherein forming a single seal includes, wherein the sealing zone includes bringing a wire mounted over the a into contact the web, wherein the releaser is mounted on an insert, and the insert is mounted on a support bar.  
     
     
         45 . The method of  claim 28  wherein forming a single seal includes, wherein the sealing zone includes bringing a wire mounted on a support bar into contact the web.  
     
     
         46 . An apparatus for making bags comprising: 
 means for receiving a web;    means for forming a single seal on the web, disposed to receive the web from the means for receiving and mounted on a rotary drum;    means for forming a weakened area within the single seal for at least a portion of the time the seal is being formed, mounted on the rotary drum.    
     
     
         47 . The apparatus of  claim 46 , wherein the means for forming a weakened area includes means for forming a perforation.  
     
     
         48 . The apparatus of  claim 47 , further including means for applying power to the means for forming a weakened area at an adjustable voltage.  
     
     
         49 . The apparatus of  claim 48 , further comprising means for monitoring a signal indicative of and controlling the power in response to the monitoring, controllably connected to the means for forming a perforation.  
     
     
         50 . The apparatus of  claim 49 , further comprising means for pulsing the power connected to the means for forming a perforation.  
     
     
         51 . The apparatus of  claim 46 , wherein the single seal extends at most 0.25 inches in the machine direction.  
     
     
         52 . The apparatus of  claim 46 , wherein the single seal extends at most 0.125 inches in the machine direction.  
     
     
         53 . A perforator for a rotary bag machine comprising an insert for a rotary drum including a weakening zone within a single sealing zone.  
     
     
         54 . The perforator of  claim 53 , wherein the perforator includes a heating wire.  
     
     
         55 . The perforator of  claim 54 , further comprising a source of power at an adjustable voltage connected to the wire.  
     
     
         56 . The perforator of  claim 55 , wherein the heating wire is disposed to be able to make intermittent contact with a web.  
     
     
         57 . The perforator of  claim 54 , wherein the heating wire is a nickel chromium resistance wire.  
     
     
         58 . The perforator of  claim 53 , wherein the insert is a glass mica ceramic with the wire disposed therein.  
     
     
         59 . The perforator of  claim 58 , wherein the insert has a plurality of holes disposed along a line in the cross direction.  
     
     
         60 . The perforator of  claim 53 , wherein the insert includes a thin film heater.  
     
     
         61 . The perforator of  claim 53 , wherein the insert includes a toothed blade.  
     
     
         62 . The perforator of  claim 53 , wherein the single sealing zone extends at most 0.25 inches in the machine direction.  
     
     
         63 . The perforator of  claim 53 , wherein the single sealing zone extends at most 0.125 inches in the machine direction.  
     
     
         64 . The perforator of  claim 53 , wherein the single sealing zone is comprised of two parallel sealing subzones and the weakening zone is disposed between the two parallel sealing subzones.  
     
     
         65 . The perforator of  claim 53 , wherein the first sealing zone and the weakening zone include a wire, a releasing layer, and a heat insulating layer, wherein the releasing layer is between the wire and the heat insulating layer, and the wire is disposed to comes into contact with the web.  
     
     
         66 . The perforator of  claim 65 , wherein the first sealing zone is mounted on an insert in an aluminum block heater.  
     
     
         67 . The perforator of  claim 65 , wherein the releasing layer is comprised of at least one of teflon, kapton, and rulon.  
     
     
         68 . The perforator of  claim 67 , wherein the insert is comprised of glass mica and has a plurality of holes disposed along a line in the cross direction.  
     
     
         69 . The perforator of  claim 67 , wherein the insulating layer is comprised of at least one of glass therm and mica.  
     
     
         70 . The perforator of  claim 53 , wherein the insert includes a first face disposed to contact the web and is further comprised of a double sided tape having a first side disposed to be affixed to a supporting structure, a resistance heater affixed to a second side of the double sided tape, a heat conductive layer, affixed to the resistance heater, an releasing and electrical insulating layer affixed to the heat conductive layer, and a wire heater affixed to the releasing and electrical insulating layer, wherein the wire heater is disposed to be in thermal contact with the web.  
     
     
         71 . The perforator of  claim 53 , wherein the insert includes a wire, a releasing layer, and a heat insulating layer, wherein the releasing layer is between the wire and the heat insulating layer, and the wire is disposed to comes into contact with the web.  
     
     
         72 . The perforator of  claim 53  wherein the first sealing zone extends a first portion of a distance across the web, and a second sealing zones extends across a second portion of the distance across the web, wherein the second sealing zone forms two parallel seals and a weakened area disposed between the two parallel seals.  
     
     
         73 . The perforator of  claim 53  wherein the first sealing zone includes at least two parallel sealing subzones, extending in the cross machine direction, and the perforating zone is disposed between the at least two parallel sealing subzones.  
     
     
         74 . The perforator of  claim 53 , wherein the sealing zone includes a support bar, an insert mounted on the support bar, a releaser mounted on the insert, and a wire mounted over the releaser disposed to contact the web.  
     
     
         75 . The perforator of  claim 74 , wherein the support bar is an aluminum block heater.  
     
     
         76 . The perforator of  claim 74 , wherein the releasing layer is comprised of at least one of teflon, kapton, and rulon.  
     
     
         77 . The perforator of  claim 53 , wherein the sealing zone includes a wire mounted on a support bar and disposed to contact the web.  
     
     
         78 . The perforator of  claim 53 , wherein the sealing zone includes a support bar, a thin film heater mounted on the support bar, and a wire heater mounted on the thin film heater such that the wire heater is disposed to contact the web.  
     
     
         79 . The perforator of  claim 53 , wherein the sealing zone includes a source of hot fluid.