CA2040587A1 - Apparatus for heat-sealing a thermoplastic packaging bag - Google Patents

Apparatus for heat-sealing a thermoplastic packaging bag

Info

Publication number
CA2040587A1
CA2040587A1 CA002040587A CA2040587A CA2040587A1 CA 2040587 A1 CA2040587 A1 CA 2040587A1 CA 002040587 A CA002040587 A CA 002040587A CA 2040587 A CA2040587 A CA 2040587A CA 2040587 A1 CA2040587 A1 CA 2040587A1
Authority
CA
Canada
Prior art keywords
heating
band
carrier body
sealing
metal carrier
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002040587A
Other languages
French (fr)
Inventor
Peter Wehle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Schweizerische Industrie Gesellschaft
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2040587A1 publication Critical patent/CA2040587A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/18—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools
    • B29C65/22—Heated wire resistive ribbon, resistive band or resistive strip
    • B29C65/229—Heated wire resistive ribbon, resistive band or resistive strip characterised by the means for tensioning said heated wire, resistive ribbon, resistive band or resistive strip
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/18—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools
    • B29C65/22—Heated wire resistive ribbon, resistive band or resistive strip
    • B29C65/221—Heated wire resistive ribbon, resistive band or resistive strip characterised by the type of heated wire, resistive ribbon, band or strip
    • B29C65/224—Heated wire resistive ribbon, resistive band or resistive strip characterised by the type of heated wire, resistive ribbon, band or strip being a resistive ribbon, a resistive band or a resistive strip
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/05—Particular design of joint configurations
    • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/112—Single lapped joints
    • B29C66/1122—Single lap to lap joints, i.e. overlap joints
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/05—Particular design of joint configurations
    • B29C66/20—Particular design of joint configurations particular design of the joint lines, e.g. of the weld lines
    • B29C66/23—Particular design of joint configurations particular design of the joint lines, e.g. of the weld lines said joint lines being multiple and parallel or being in the form of tessellations
    • B29C66/232—Particular design of joint configurations particular design of the joint lines, e.g. of the weld lines said joint lines being multiple and parallel or being in the form of tessellations said joint lines being multiple and parallel, i.e. the joint being formed by several parallel joint lines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/40—General aspects of joining substantially flat articles, e.g. plates, sheets or web-like materials; Making flat seams in tubular or hollow articles; Joining single elements to substantially flat surfaces
    • B29C66/41—Joining substantially flat articles ; Making flat seams in tubular or hollow articles
    • B29C66/43—Joining a relatively small portion of the surface of said articles
    • B29C66/431—Joining the articles to themselves
    • B29C66/4312—Joining the articles to themselves for making flat seams in tubular or hollow articles, e.g. transversal seams
    • B29C66/43121—Closing the ends of tubular or hollow single articles, e.g. closing the ends of bags
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/40—General aspects of joining substantially flat articles, e.g. plates, sheets or web-like materials; Making flat seams in tubular or hollow articles; Joining single elements to substantially flat surfaces
    • B29C66/47—Joining single elements to sheets, plates or other substantially flat surfaces
    • B29C66/474—Joining single elements to sheets, plates or other substantially flat surfaces said single elements being substantially non-flat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/73—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
    • B29C66/739—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset
    • B29C66/7392—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
    • B29C66/814—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the design of the pressing elements, e.g. of the welding jaws or clamps
    • B29C66/8145—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the design of the pressing elements, e.g. of the welding jaws or clamps characterised by the constructional aspects of the pressing elements, e.g. of the welding jaws or clamps
    • B29C66/81457—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the design of the pressing elements, e.g. of the welding jaws or clamps characterised by the constructional aspects of the pressing elements, e.g. of the welding jaws or clamps comprising a block or layer of deformable material, e.g. sponge, foam, rubber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
    • B29C66/816—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the mounting of the pressing elements, e.g. of the welding jaws or clamps
    • B29C66/8161—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the mounting of the pressing elements, e.g. of the welding jaws or clamps said pressing elements being supported or backed-up by springs or by resilient material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
    • B29C66/818—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
    • B29C66/818—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps
    • B29C66/8181—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps characterised by the cooling constructional aspects
    • B29C66/81811—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps characterised by the cooling constructional aspects of the welding jaws
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/83—General aspects of machine operations or constructions and parts thereof characterised by the movement of the joining or pressing tools
    • B29C66/832—Reciprocating joining or pressing tools
    • B29C66/8322—Joining or pressing tools reciprocating along one axis
    • B29C66/83221—Joining or pressing tools reciprocating along one axis cooperating reciprocating tools, each tool reciprocating along one axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/71—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
    • B29C66/812—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
    • B29C66/8122—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps characterised by the composition of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B70/00—Making flexible containers, e.g. envelopes or bags
    • B31B70/60—Uniting opposed surfaces or edges; Taping
    • B31B70/64—Uniting opposed surfaces or edges; Taping by applying heat or pressure
    • B31B70/642—Uniting opposed surfaces or edges; Taping by applying heat or pressure using sealing jaws or sealing dies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B70/00—Making flexible containers, e.g. envelopes or bags
    • B31B70/74—Auxiliary operations
    • B31B70/81—Forming or attaching accessories, e.g. opening devices, closures or tear strings
    • B31B70/813—Applying closures
    • B31B70/8131—Making bags having interengaging closure elements

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Package Closures (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE

An apparatus for welding a sealing strip to respective inner faces of two superposed thermoplastic sheets and for directly welding the superposed thermoplastic sheets to one another by a weld spaced from and oriented generally parallel to the sealing strip. The apparatus includes a first sealing device having a first metal carrier body and two parallel-spaced first and second heating bands attached thereto; a second sealing device having a metal carrier body and a third heating band attached thereto. The third heating band faces and is in alignment with, the first sealing band.
The second sealing device further has a resilient band attached to its metal carrier body. The resilient band faces and is in alignment with, the second heating band. A
mechanism moves the first and second sealing devices toward one another for engaging outer faces of the superposed thermoplastic sheets by a cooperation between the first and third heating bands and between the second heating band and the resilient band.

Description

- 2 0 ~ 7 S BACKGROU~D OF THE INVENTION

This invention relates to an apparatus for heat-sealing (welding) a two-part sealing strip between two thermoplastic sheets and for bonding the two sheets to one another. The apparatus includes two oooperating sealing devices.
A known apparatus of the above-outlined type is dis-closed, for example, in German Gebrauchsmuster (utility patent model) 88 03 021. In tAis prior art construction a thermoplastic sheet is advanced cyclically through a length which corresponds to the length of the finished bag. First, the two parts of a sealing strip are welded next to one another onto the sheet and thereafter the sheet is deformed into a hose configuration and provided with a longitudinal sea~. As the next step, above the now-closed sealing strip a peelable seal~ng seam and thereabove, a transverse sealing seam are simultaneously welded. After welding the transverse sealing seam, the hose portion which is situated above the 2 ~ 7 transverse sealing seam is chargect with a metered quantity of goods and, in a next step, the bag is sealed at the top and is further conveyed. For storage and further transport the bags are thus hermetically sealed by the peelable weld seam.
After opening of t~e bag it may be reclosed by the sealing strip. It is a disadvantage of the ~nown apparatus that it is of complex construction and it operates relatively slowly.
It is further known, for example, from U.S. Patent No.
4,630,429, to jointly weld two side-by-side arranged trans-verse sealing seams and to sever the hose between the two seams.

SUMMARY OF THE INYENTION

It is an object of the invention to provide an improved apparatus of the above-outlined type which is of compact construction and has a greater output than devices of the prior art.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the apparatus includes a first sealing device having a first metal carrier body and two parallel-spaced first and second heating bands attached ~0~7 thereto; a second sealing device having a ~etal carrier body and a third heating band attached thereto. The third heating band faces and is in alignment with, the first sealing band.
The second sealing device further has a resilient band attached to its metal carrier body. The resilient band faces and is in alignment with, the second heating band. A
mechanism moves the first and second sealing devices toward one another for engaging outer faces of the superposed thermoplastic sheets by a cooperation between the first and third heating bands and between the second heating band and the resilient band.

BRIEF DESCRIPTION OF THE DRAWING

i Figure 1 is a perspective view of a bag made by an apparatus according to the invention.
; 15 Figure 2 is an enlarged sectional view of one part of the structure shown in Figure 1, taken along a plane which is perpendicular to arrows II, II of Figure 1.
Figure 3 is a schematic side elevational view of a preferred embodiment of the invention.
Figure 4 is a sectional end elevational view of one part of the construction shown in Figure 3.

Figure 5 is a sectional view ta~en along line V-V of Figure 4.
Figure 6 is a sectional view taken along line VI-VI of Figure 4.

DESCRIPTION OF~rHE PREFERRED EMBODIMENT

Turning to Figures 1 and 2, the packaging bag 1 shown therein is formed of two polyethylene sheets 2 and 3 closed at the top by a sealing strip 4 and a peelable seam 5. The sealing strip 4 is formed of two shaped polyethylene strips 6 and 7 which interengage in a snap-in connection. The two sheets 2 and 3 are laterally sealed by a longitudinal sealing seam 8 on each side and by means of an end face seal 9 in a known, hermetic manner.
Turning now to Figure 3, the apparatus shown therein includes a carriage 13 movable horizontally on a rail 12.
Two ends of a toothed belt 14 which is guided by two end sprockets 15 and 16 are secured to the carriage 13. The sprocket 16 is driven by a servomotor 17.
Also referring to Figure 4, in a dovetail guide lB
provided in the carriage frame, two sealing devices 20, 21 axe displaceably guided in a direction transverse to the length direction of the rail 12. The sheets 2 and 3 are 2 ~ 7 withdrawn from respective supply xeels 23 (only one is ~isible) held by a rotary core 24 and decelerated by a brake 2~. The sheets 2 and 3 are maintained taut between the supply reels 23 and a pair of withdrawing rolls 26 (only one is visible) which are continuously rotated by a motor 27.
The sealing strip 4 is removed from a supply reel 29 and is introduced between the two sheets 2 and 3, adjacent their upper edge 32, by two guide plates 30, 31.
Also referring to Figure 5, the two sealing devices 20 and 21 are shiftable between two non-illustrated stops in guides 18 by means of respective pneumatic cylinders 35 and 36. The cylinder 35 shifts the sealing device 20 with the intermediary of a beam 37 and biased springs 38 as shown in Figure 5. The magnitude of bias of the springs 38 determines the pressing force during the sealing step. The sealing device 20 has a metallic carrier body 41 and two heating bands 42, 43 which are oriented parallel to one another and to the rail 12. The heating bands 42 and 43 are positioned on respective elastic synthetic strips 44 made, for example, of a Teflon-coated silicone elastomer or a fiberglass reinforced synthetic material. The strips 44 are glued on a respective rail 45 made, for example, of copper. The rails 45 are mounted in the carrier body 41 which has a bore 46 for the passage of a coolant. At both ends the flexible heating 2 ~

bands 41 and 42 are guide~ over a cylindrical segment-shaped surface of a shoe 47 and are clamped thereto by screws 48.
Each end of the heating bands 42, 43 is connected to a non-illustrated, controllable current source by means of conduc-tors 49. The shoes 47 are connected with the intermediary ofan insulating layer 50 with an arm 51 which is pivotal about a shaft 52 oriented perpendicularly to the length dimension of the heating bands and which is biased by a spring 53. The springs 53 tension the heating bands 42, 43 and compensate for their length variation in case of a pulse-like heating and subsequent cooling thereof.
In the sealing device 21 parts which are identical to those belonging to the sealing device 20 are designated with the szme reference numerals and have essentially the same construction and function so that a detailed description thereof may be dispensed with. The sealing device 21 differs from the sealing device 20 in that the former has but a sole heating band 57. Below the heating band 57 there is arranged an elastic strip 58 which is spaced center-to-center from the heating band 57 to the same extent as the center-to-center distance between the heating bands 42 and 43. The elastic strip 58 which may be, for example, a silicone elastomer component, is embedded in a rail 59 and projects beyond a plane containing the outer face of the heating band 2~0~7 57. The rail 59 is displaceable in a groove 60 of a carrier body 61 perpendicularly to the length dimension of the strip 58 and parallel to the guide 18, against the force of the biased springs 62 which press the rail 59 against stops 63, as shown in Figure 6.
In the description which follows, the operation of the above-described apparatus will be set forth.
The pair of rolls 26 continuously draws off the sheets 2 and 3 as well as the sealing strip 4 from the supply reels 23 and 29. The carriage 13 is reciprocated by the servomotor 17. When the motion of the carriage 13 coincides with the direction of sheet removal, the carriage speed is accurately adapted to the sheet removal speed. As soon as the carriage motion is initiated in the direction of sheet withdrawal, the two cylinders 35 and 36 are actuated and the two sealing devices 20 and 21 are moved towards one another in the guides 18. The heating bands 42, 57 and the heating band 43, as well as the strip 58 are pressed to one another by the force set for the springs 38, while the force distribution is predetermined by the bias of the springs 62.
Thereafter, pulse-like current is applied to the conductors 49 so that the heating bands 42, 43 and 57 are heated to the temperature required for the sealing process.
The pulse applied to the heating band 43 is slightly shorter 2 ~

to ensure ~hat the sealing seam 5 is peelable, that is, the sheets 2 and 3 are not bonded together with a throughgoing weld. The pressing force is maintained until the sealing seams are sufficiently cooled to ensure the required strength of the seams. Thereafter, the carrier bodies 41 and 61 are moved away from one another by means of the cylinders 35 and 36, and the carriage 13 is withdrawn so that the subsequent seams may be provided in the next step immediately at the just-completed seam.
Downstream of the withdrawing rolls 26 (as viewed in the direction of sheet travel) the longitudinal seams 8 are formed by a conventional device, such as disclosed, for example, in U.S. Patent No. 4,630,429 and the individual bags are severed from one another. The bags are then charged with the goods through the still-open underside and are eventually provided in a conventional manner with a frontal seal 9.
- The described apparatus has the advantage that in a single operational step the peelable seam is formed and the sealing strip 4 is welded in. Since subsequently in the packing machine individual bags are being charged with goods, the latter may be more accurately metered than, for example, in an apparatus constructed according to German Gebrauchs-muster 88 03 021. In the apparatus according to the inven-tion the manufacturing speed for the bags may be sig-2~0~7 nificantly increased because such speed is not limited by thefilling process. The apparatus according to the invention has the further advantage over the prior art construction that the sealing strips of the bags close with better seal because they extend throughout the entire width of the bag and are at their ends closed with longitudinal seams 8 which is not feasible in bags according to the German Gebrauchs-muster 88 03 021.
It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended wi~hin the meaning and range of equivalents of the appended claims.

Claims (12)

1. An apparatus for welding a sealing strip to respec-tive inner faces of two superposed thermoplastic sheets and for directly welding the superposed thermoplastic sheets to one another by a weld spaced from and oriented generally parallel to the sealing strip, comprising (a) a first sealing device having (1) a first metal carrier body;
(2) two parallel-spaced first and second heating bands attached to said first metal carrier body;
(b) a second sealing device having (1) a second metal carrier body;
(2) a third heating band attached to the second metal carrier body; said third heating band facing and being in alignment with said first sealing band;
(3) a resilient band attached to said second metal carrier body; said resilient band facing and being in alignment with said second heating band;
(c) means for positioning the thermoplastic sheets between the first and second sealing device;
(d) means for positioning the sealing strip between the thermoplastic sheets;

(e) means for heating the first, second and third heating bands; and (f) actuating means for moving the first and second sealing devices toward one another for engaging outer faces of the superposed thermoplastic sheets by a cooperation between the first and third heating bands and between the second heating band and the resilient band.
2. An apparatus as defined in claim 1, wherein said resilient band projects in height beyond a plane containing an outer face of said third heating band.
3. An apparatus as defined in claim 1, further compris-ing spring means for resiliently holding at least one of said metal carrier bodies on said actuating means.
4. An apparatus as defined in claim 1, further compris-ing a bore in the metal carrier bodies for guiding a coolant therein.
5. An apparatus as defined in claim 1, wherein said means for positioning the sealing strip comprises a guide for guiding the sealing strip.
6. An apparatus as defined in claim 1, wherein each said heating hand has a length dimension; further comprising a carriage on which said first and second metal carrier bodies are mounted and moving means for displacing said carriage parallel to said length dimension.
7. An apparatus as defined in claim 1, further compris-ing a first clamping device movably mounted on said first metal carrier body and a second clamping device movably mounted on said second metal carrier body; said first and second clamping devices each including clamping mechanisms for clamping opposite ends of said first, second and third heating bands, and spring means for urging the clamping mechanisms of the respective clamping means away from one another for tensioning the heating bands.
8. An apparatus as defined in claim 7, wherein each heating band is flexible and has a length; said ends of each said heating band extending in a plane oriented perpen-dicularly to respective said lengths of the heating bands.
9. An apparatus as defined in claim 1, further compris-ing a respective resilient support member provided between the first carrier body and the first heating band, between the first carrier body and the second heating band and between the second carrier body and the third heating band.
10. An apparatus as defined in claim 9, wherein said resilient support member is a plastic.
11. An apparatus as defined in claim 10, wherein said plastic is a Teflon-coated elastomer.
12. An apparatus as defined in claim 10, wherein said plastic is fiberglass-reinforced.
CA002040587A 1990-04-20 1991-04-16 Apparatus for heat-sealing a thermoplastic packaging bag Abandoned CA2040587A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH134190 1990-04-20
CH1341/90-5 1990-04-20

Publications (1)

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CA2040587A1 true CA2040587A1 (en) 1991-10-21

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EP (1) EP0453408A1 (en)
CA (1) CA2040587A1 (en)

Cited By (1)

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Publication number Priority date Publication date Assignee Title
US6422987B1 (en) * 1997-11-19 2002-07-23 Harro Hofliger Verpackungsmachinen Gmbh Apparatus for producing recloseable bags

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
US6244021B1 (en) * 1999-05-21 2001-06-12 Illinois Tool Works Inc. Method of applying reclosable zipper to package
US6665999B1 (en) * 1999-09-07 2003-12-23 Recot, Inc. Seal jaw modules for reclose bag modification to vertical form, fill, and seal packaging system
US8650843B2 (en) 2011-02-04 2014-02-18 Alpma Alpenland Maschinenbau Gmbh Method of packaging products

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FR1152998A (en) * 1956-06-29 1958-02-27 Device for fitting plastic closures
FR1255003A (en) * 1960-01-19 1961-03-03 Neb Ets Method and device for applying profiled closure strips to plastic bags
DE1246219B (en) * 1962-12-12 1967-08-03 Windmoeller & Hoelscher Heat pulse bar for welding devices for welding thermoplastics
US3321353A (en) * 1963-03-08 1967-05-23 Weldotron Corp Film sealing and cutting apparatus
FR1525718A (en) * 1967-06-06 1968-05-17 Windmoeller & Hoelscher Device for fixing by welding strips for machines intended for the manufacture of plastic bags or sachets with press-stud or zipper
US3703427A (en) * 1971-06-01 1972-11-21 John C Sellers Thermal impulse sealing bar assembly
US3748207A (en) * 1971-08-26 1973-07-24 Kimberly Clark Co Mechanism for heat sealing
SE392084B (en) * 1972-10-03 1977-03-14 Tetra Pak Int ASSEMBLY THAT WHEN SHRINKING MOVEMENT OF FOREMAL REPLACES AN OPENING DEVICE IN THE FORM OF A RIP STRIP

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6422987B1 (en) * 1997-11-19 2002-07-23 Harro Hofliger Verpackungsmachinen Gmbh Apparatus for producing recloseable bags

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Publication number Publication date
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