WO1988001933A1 - Apparatus for heat sealing sheets of thermoplastic material between two electrodes - Google Patents

Apparatus for heat sealing sheets of thermoplastic material between two electrodes Download PDF

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Publication number
WO1988001933A1
WO1988001933A1 PCT/US1987/002201 US8702201W WO8801933A1 WO 1988001933 A1 WO1988001933 A1 WO 1988001933A1 US 8702201 W US8702201 W US 8702201W WO 8801933 A1 WO8801933 A1 WO 8801933A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrode
flexible tube
counter
electrodes
sheets
Prior art date
Application number
PCT/US1987/002201
Other languages
French (fr)
Inventor
Pierre Soubrier
Original Assignee
Baxter Travenol Laboratories, Inc.
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 Baxter Travenol Laboratories, Inc. filed Critical Baxter Travenol Laboratories, Inc.
Publication of WO1988001933A1 publication Critical patent/WO1988001933A1/en

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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
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/004—Preventing sticking together, e.g. of some areas of the parts to be joined
    • B29C66/0042—Preventing sticking together, e.g. of some areas of the parts to be joined of the joining tool and the parts to be joined
    • B29C66/0044—Preventing sticking together, e.g. of some areas of the parts to be joined of the joining tool and the parts to be joined using a separating sheet, e.g. fixed on the joining tool
    • B29C66/00441—Preventing sticking together, e.g. of some areas of the parts to be joined of the joining tool and the parts to be joined using a separating sheet, e.g. fixed on the joining tool movable, e.g. mounted on reels
    • 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
    • B29C65/04—Dielectric heating, e.g. high-frequency welding, i.e. radio frequency welding of plastic materials having dielectric properties, e.g. PVC
    • 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
    • B29C66/40—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
    • 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
    • B29C66/73921—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 characterised by the materials of both parts being thermoplastics
    • 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
    • B29C66/8141—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 surface geometry of the part of the pressing elements, e.g. welding jaws or clamps, coming into contact with the parts to be joined
    • B29C66/81411—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 surface geometry of the part of the pressing elements, e.g. welding jaws or clamps, coming into contact with the parts to be joined characterised by its cross-section, e.g. transversal or longitudinal, being non-flat
    • B29C66/81421—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 surface geometry of the part of the pressing elements, e.g. welding jaws or clamps, coming into contact with the parts to be joined characterised by its cross-section, e.g. transversal or longitudinal, being non-flat being convex or concave
    • B29C66/81422—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 surface geometry of the part of the pressing elements, e.g. welding jaws or clamps, coming into contact with the parts to be joined characterised by its cross-section, e.g. transversal or longitudinal, being non-flat being convex or concave being convex
    • 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
    • B29C66/81455—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 being a fluid inflatable bag or bladder, a diaphragm or a vacuum bag for applying isostatic pressure
    • 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
    • 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
    • B29C66/84—Specific machine types or machines suitable for specific applications
    • B29C66/851—Bag or container making machines
    • B29C66/8511—Bag making machines
    • 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
    • B29C65/38—Impulse heating
    • 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
    • B29C65/78—Means for handling the parts to be joined, e.g. for making containers or hollow articles, e.g. means for handling sheets, plates, web-like materials, tubular articles, hollow articles or elements to be joined therewith; Means for discharging the joined articles from the joining apparatus
    • B29C65/7858—Means for handling the parts to be joined, e.g. for making containers or hollow articles, e.g. means for handling sheets, plates, web-like materials, tubular articles, hollow articles or elements to be joined therewith; Means for discharging the joined articles from the joining apparatus characterised by the feeding movement of the parts to be joined
    • B29C65/7888—Means for handling of moving sheets or webs
    • B29C65/7891—Means for handling of moving sheets or webs of discontinuously moving sheets or webs
    • 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
    • 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
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/92—Measuring or controlling the joining process by measuring or controlling the pressure, the force, the mechanical power or the displacement of the joining tools
    • B29C66/924—Measuring or controlling the joining process by measuring or controlling the pressure, the force, the mechanical power or the displacement of the joining tools by controlling or regulating the pressure, the force, the mechanical power or the displacement of the joining tools
    • B29C66/9241—Measuring or controlling the joining process by measuring or controlling the pressure, the force, the mechanical power or the displacement of the joining tools by controlling or regulating the pressure, the force, the mechanical power or the displacement of the joining tools by controlling or regulating the pressure, the force or the mechanical power
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/712—Containers; Packaging elements or accessories, Packages
    • B29L2031/7128—Bags, sacks, sachets

Definitions

  • the present invention relates to apparatus for heat sealing sheets of thermoplastic material between two electrodes. It relates more particularly to apparatus that can heat seal sheets composed of, for example, polyethylene or polypropylene, especially for the fabrication of flexible bags or containers holding a perfusion liquid to be administered to a patient intravenously.
  • the apparatus according to the present invention is used for impulse heat sealing sheets of thermoplastic material along a horizontal or vertical line forming the bottom or the lateral wall, respectively, of a flexible bag.
  • thermoplastic material Presently utilized in the art for heat sealing sheets of thermoplastic material is a device comprising an electrode movable with respect to a counter-electrode which can be fixed or movable. Two sheets that are positioned between these two electrodes are to be heat sealed together. The movable electrode then moves to bear upon the counter-electrode, with the two sheets positioned in between, to heat seal the sheets of thermoplastic material to one another at the location where they are pinched between the electrodes. To achieve good impulse heat sealing it is important to cont r ol two parameters: the length of time of the heat sealing procedure and the pressure exerted by the electrodes on the sheets to be heat sealed. In the prior a the heads of the electrodes that came into contact with the sheets of thermoplastic material have a hard surface, so that the pressure between these heads cannot be regulated.
  • An object of the present invention is to provide a heat sealing apparatus that can regulate the pressure exerted by the electrode heads for the duration of each heat sealing cycle, i.e. during the pressing of the sheets between the electrodes, during the heat sealing of the sheets together, and during the crystallization of the heat sealing band.
  • the apparatus for heat sealing sheets of thermoplastic material between two electrodes is characterized by one of the electrodes having a deformable part. The deformation of this part is regulated while the electrodes are in contact with the sheets of thermoplastic material to be heat sealed.
  • the deformable part is included in the counter-electrode, fixed or movable, that cooperates with an electrode that is movable with respect to the counter-electrode.
  • the deformable part of the counter-electrode preferably comprises a flexible tube lodged in a cavity in the counter-electrode head which faces the head of the movable electrode.
  • This flexible tube is connected to a compressed ai source which creates in the flexible tube a controllable pressure that prevents its deformation by the head of the movable electrode.
  • the pressure existing in the flexible tube is, accordingly, a counterpressure to the pressure exerted by the head of the movable electrode on this flexible tube.
  • Another feature of the instant invention is that the flexible tube, only one portion of which protrudes from the head of the counter-electrode, is protected by a strip that is displaceable step by step over the head of the counter-electrode. This protective strip is rolled at each end over a roller and is guided in grooves provided in the counter-electrode.
  • Fig. 1 is a side view of the heat sealing apparatus that is the subject of the instant invention.
  • Fig. 2 is a front view of the counter-electrode.
  • the heat sealing apparatus shown in the drawings comprises a movable electrode 1, a portion of which is shown in Fig. 1. Electrode 1 is moved back and forth in the direction of the arrows X and is positioned adjacent a counter-electrode 2 that is fixed in a support 3. Electrodes 1 and 2 are in the shape of bars, the length of which is approximately equal to the length of the heat seal to be formed between two sheets 4 and 5 of thermoplastic material. Sheets 4 and 5 are intermittently moved along within the apparatus in the direction of the arrow Y.
  • the movable electrode 1 includes a head 6 that is moved into contact with the outer face of the sheet 4 of thermoplastic material, at the location where sheet 4 is to be heat sealed to sheet 5.
  • the counter-electrode 2 includes a head 7 having a longitudinal cavity 8.
  • Cavity 8 houses a flexible tube 9 of rubber, silicone or other similar material. A small portion of the exterior surface of flexible tube 9 protrudes from cavity 8 and faces head 6 of movable electrode 1.
  • flexible tube 9 is connected at each end to a junction 10, one of which is connected to a source of compressed air (not shown).
  • the other junction 10 is connected to a conduit 11 having a gate valve 12 which allows for the regulation of the ai " pressure in the flexible tube 9.
  • a strip 13 of a heat resistance material extends from a roll 14, through guide grooves 15, to the front of head 7 of the counter-electrode. Strip 13 then passes through guide grooves 16 and ends at a roll 17. Strip 13 protects the flexible tube 9 from deterioration caused by heat. Strip 13 may be moved intermittently in the direction of arrows Z. r
  • the heat sealing apparatus described above functions in the following manner.
  • sheets 4 and 5 of polyolefin material for example, have been moved in the direction of arrow Y until that portion of the sheets to be heat sealed together is positioned between electrodes I and 2, the movable electrode 1 is displaced toward the fixed counter-electrode 2.
  • the pressure of compressed air in the flexible tube 9 carried by the counter-electrode 2 is regulated.
  • the pressure in the flexible tube is a counterpressure to the closing pressure exerted by the movable electrode 1 on the counter-electrode 2.
  • the heat sealing apparatus taught by the present invention provides for a uniform pressure between the electrodes 1 and 2 during the welding of sheets 4 and 5, which results in an improved heat seal.
  • the heat sealing apparatus with flexible tube 9, described herein advantageously provides the regulating of the pressure in tube 9 as a function of the heat sealing and crystallization characteristics of the sheets 4 and 5, and as a function of the profile of the heat seal band desired.
  • movable electrode 1 separates from fixed counter-electrode 2 and the air pressure in flexible tube 9 is reduced to a predetermined level. As soon as electrodes 1 and 2 are separated by a sufficientdistance, sheets of thermoplastic material 4 and 5 are displaced in the direction Y to the next position where they are to be heat sealed. The cycle described above is then repeated.
  • protective strip 13 can be moved in the direction of one of the arrows Z, so that a new portion of strip 13 covers flexible tube 9.
  • the control of the intermittent displacement of the protective strip 13 may be either mechanical or manual.
  • the width of strip 13 corresponds to the length of the heat sealing band 18 and may be slightly less than the length of flexible tube 9.

Abstract

An apparatus for impulse sealing thermoplastic sheets (4, 5). The apparatus includes two electrodes (1, 2), at least one of which is movable (1) and at least one of which has a deformable head. The deformable head includes a flexible tube (9) housed in a cavity (8) of one of the electrodes. Compressed air controls the deformation of the tube. A protective strip (13) overlays the deformable head and may be advanced when necessary to provide a new protective cover for the flexible tube (9).

Description

APPARATUS FOR HEAT SEALING SHEETS OF THERMOPLASTIC MATERIAL
BETWEEN TWO ELECTRODES
Field of the Invention
The present invention relates to apparatus for heat sealing sheets of thermoplastic material between two electrodes. It relates more particularly to apparatus that can heat seal sheets composed of, for example, polyethylene or polypropylene, especially for the fabrication of flexible bags or containers holding a perfusion liquid to be administered to a patient intravenously.
The apparatus according to the present invention is used for impulse heat sealing sheets of thermoplastic material along a horizontal or vertical line forming the bottom or the lateral wall, respectively, of a flexible bag.
Description Of Related Art
Presently utilized in the art for heat sealing sheets of thermoplastic material is a device comprising an electrode movable with respect to a counter-electrode which can be fixed or movable. Two sheets that are positioned between these two electrodes are to be heat sealed together. The movable electrode then moves to bear upon the counter-electrode, with the two sheets positioned in between, to heat seal the sheets of thermoplastic material to one another at the location where they are pinched between the electrodes. To achieve good impulse heat sealing it is important to control two parameters: the length of time of the heat sealing procedure and the pressure exerted by the electrodes on the sheets to be heat sealed. In the prior a the heads of the electrodes that came into contact with the sheets of thermoplastic material have a hard surface, so that the pressure between these heads cannot be regulated.
Summary of the Invention An object of the present invention is to provide a heat sealing apparatus that can regulate the pressure exerted by the electrode heads for the duration of each heat sealing cycle, i.e. during the pressing of the sheets between the electrodes, during the heat sealing of the sheets together, and during the crystallization of the heat sealing band.
According to the present invention, the apparatus for heat sealing sheets of thermoplastic material between two electrodes, at least one of which is movable with respect to the other, is characterized by one of the electrodes having a deformable part. The deformation of this part is regulated while the electrodes are in contact with the sheets of thermoplastic material to be heat sealed.
In one embodiment of the invention, the deformable part is included in the counter-electrode, fixed or movable, that cooperates with an electrode that is movable with respect to the counter-electrode.
The deformable part of the counter-electrode preferably comprises a flexible tube lodged in a cavity in the counter-electrode head which faces the head of the movable electrode. This flexible tube is connected to a compressed ai source which creates in the flexible tube a controllable pressure that prevents its deformation by the head of the movable electrode. The pressure existing in the flexible tube is, accordingly, a counterpressure to the pressure exerted by the head of the movable electrode on this flexible tube. Another feature of the instant invention is that the flexible tube, only one portion of which protrudes from the head of the counter-electrode, is protected by a strip that is displaceable step by step over the head of the counter-electrode. This protective strip is rolled at each end over a roller and is guided in grooves provided in the counter-electrode.
Other features and details of the invention will become apparent from the following detailed description and drawings which illustrate, as an example, apparatus that is an embodiment of the instant invention.
Brief Description of the Drawings
Fig. 1 is a side view of the heat sealing apparatus that is the subject of the instant invention. Fig. 2 is a front view of the counter-electrode.
Description of the Preferred Embodiment
The heat sealing apparatus shown in the drawings comprises a movable electrode 1, a portion of which is shown in Fig. 1. Electrode 1 is moved back and forth in the direction of the arrows X and is positioned adjacent a counter-electrode 2 that is fixed in a support 3. Electrodes 1 and 2 are in the shape of bars, the length of which is approximately equal to the length of the heat seal to be formed between two sheets 4 and 5 of thermoplastic material. Sheets 4 and 5 are intermittently moved along within the apparatus in the direction of the arrow Y.
The movable electrode 1 includes a head 6 that is moved into contact with the outer face of the sheet 4 of thermoplastic material, at the location where sheet 4 is to be heat sealed to sheet 5. The counter-electrode 2 includes a head 7 having a longitudinal cavity 8. Cavity 8 houses a flexible tube 9 of rubber, silicone or other similar material. A small portion of the exterior surface of flexible tube 9 protrudes from cavity 8 and faces head 6 of movable electrode 1.
As shown in Fig. 2, flexible tube 9 is connected at each end to a junction 10, one of which is connected to a source of compressed air (not shown). The other junction 10 is connected to a conduit 11 having a gate valve 12 which allows for the regulation of the ai "pressure in the flexible tube 9.
A strip 13 of a heat resistance material, such as polytetra- fluorethylene, extends from a roll 14, through guide grooves 15, to the front of head 7 of the counter-electrode. Strip 13 then passes through guide grooves 16 and ends at a roll 17. Strip 13 protects the flexible tube 9 from deterioration caused by heat. Strip 13 may be moved intermittently in the direction of arrows Z. r
The heat sealing apparatus described above functions in the following manner. When sheets 4 and 5 of polyolefin material, for example, have been moved in the direction of arrow Y until that portion of the sheets to be heat sealed together is positioned between electrodes I and 2, the movable electrode 1 is displaced toward the fixed counter-electrode 2. During this displacement of the movable electrode 1, the pressure of compressed air in the flexible tube 9 carried by the counter-electrode 2 is regulated. The pressure in the flexible tube is a counterpressure to the closing pressure exerted by the movable electrode 1 on the counter-electrode 2. When the sheets 4 and 5 are pinched between the head 6 of the movable electrode and the portion of the protective strip 13 covering the flexible tube 9, electric current is sent between electrodes 1 and 2 to heat seal sheets 4 and 5 together. A predetermined air pressure is maintained in flexible tube 9 during the entire heat sealing cycle until the crystallization of the heat sealing band 18. This pressure may be somewhat higher during the heat sealing process than during the crystallization of the heat sealing band.
The heat sealing apparatus taught by the present invention provides for a uniform pressure between the electrodes 1 and 2 during the welding of sheets 4 and 5, which results in an improved heat seal. The heat sealing apparatus with flexible tube 9, described herein, advantageously provides the regulating of the pressure in tube 9 as a function of the heat sealing and crystallization characteristics of the sheets 4 and 5, and as a function of the profile of the heat seal band desired.
When the heat sealing is completed, movable electrode 1 separates from fixed counter-electrode 2 and the air pressure in flexible tube 9 is reduced to a predetermined level. As soon as electrodes 1 and 2 are separated by a sufficientdistance, sheets of thermoplastic material 4 and 5 are displaced in the direction Y to the next position where they are to be heat sealed. The cycle described above is then repeated.
If necessary, protective strip 13 can be moved in the direction of one of the arrows Z, so that a new portion of strip 13 covers flexible tube 9. The control of the intermittent displacement of the protective strip 13 may be either mechanical or manual. The width of strip 13 corresponds to the length of the heat sealing band 18 and may be slightly less than the length of flexible tube 9.
It should be understood that various changes and modifications to the embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departiny from the spirit and scope of the present invention and without diminishing its attendant advantages. It is, therefore, intended that such changes and modifications be covered by the appended claims.

Claims

I CLAIM:
1. Apparatus for heat sealing sheets of thermoplastic material between two electrodes, at least one of which is movable with respect to the other, characterized in that (2) of the electrodes (1, 2) has a deformable part (9) which is subjected to the action of a means regulating its deformation when these-electrodes (1, 2) are in contact with the sheets (4, 5) of thermoplastic material to be heat sealed together.
2. Apparatus according to Claim 1, characterized in that the above-mentioned deformable part (9) is made in a counter-electrode (2) cooperating with an electrode (1) movable with respect to this counter-electrode (2).
3. Apparatus according to either of claims 1 and 2, characterized in that means regulating the deformation of the deformable part (9) is constituted by a pressure due to a fluid such as a gas.
4. Apparatus according to any of the preceding claims, characterized in that the aforementioned deformable part is composed of a flexible tube (9).
5. Apparatus according to claim 4, characterized in that the flexible tube (9) is connected to a source of a compressed fluid, such as compressed air.
6. Apparatus according to Claim 5, characterized in that the pressure of the compressed fluid is regulatable.
7. Apparatus according to either of claims 4 and 5, characterized in that the flexible tube (9) is lodged in a cavity (8) made in the head (7) of the counter-electrode (2) facing the head (6) of the movable electrode (1).
8. Apparatus according to any of claims 4 to 7, characterized in that it comprises a means of protecting (13) the above-mentioned flexible tube (9).
9. Apparatus according to claim 8, characterized in that the protective means is composed of a sheet (13) covering a part of the flexible tube (9) protruding from the head (7) of the counter-electrode (2).
10. Apparatus according to claim 9, characterized in that the protective sheet (13) is interchangeable.
11. Apparatus according to claim 10, characterized in that the protective sheet (13) is composed of a band movable step by step over the head (7) of the counter-electrode (2).
12. Apparatus according to claim 1, characterized in that the protective band (13) is rolled at each of its ends on a roller (14, 17) and is guided into grooves (15, 16) provided in the counter-electrode (2).
13. Apparatus according to either of claims 11 and 12, characterized in that step-by-step displacement of the protective band (13) is mechanically controlled.
14. Apparatus according to any of claims 4 to 12, characterized in that the flexible tube (9) is of rubber or of an analogous material.
15. Device according to any of claims 8 to 13, characterized in the means of protection (13) of the flexible tube (9) is composed of a band of polytetraflourethylene.
PCT/US1987/002201 1986-09-09 1987-09-08 Apparatus for heat sealing sheets of thermoplastic material between two electrodes WO1988001933A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE0/217136A BE905400A (en) 1986-09-09 1986-09-09 DEVICE FOR WELDING SHEETS OF THERMOPLASTIC MATERIAL BETWEEN TWO ELECTRODES.
BE0/217136 1986-09-09

Publications (1)

Publication Number Publication Date
WO1988001933A1 true WO1988001933A1 (en) 1988-03-24

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ID=3844077

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1987/002201 WO1988001933A1 (en) 1986-09-09 1987-09-08 Apparatus for heat sealing sheets of thermoplastic material between two electrodes

Country Status (5)

Country Link
EP (1) EP0282563A4 (en)
JP (1) JPH01500813A (en)
AU (1) AU598600B2 (en)
BE (1) BE905400A (en)
WO (1) WO1988001933A1 (en)

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WO2013030114A1 (en) * 2011-08-30 2013-03-07 Bielomatik Leuze Gmbh + Co. Kg Device for thermal impulse welding
CN110679638A (en) * 2018-07-02 2020-01-14 阿尔伯特汉特曼机械制造有限公司 Closing module and method for closing and/or separating filled sausage casings

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WO2013030114A1 (en) * 2011-08-30 2013-03-07 Bielomatik Leuze Gmbh + Co. Kg Device for thermal impulse welding
CN110679638A (en) * 2018-07-02 2020-01-14 阿尔伯特汉特曼机械制造有限公司 Closing module and method for closing and/or separating filled sausage casings
CN110679638B (en) * 2018-07-02 2022-05-24 阿尔伯特汉特曼机械制造有限公司 Closing module and method for closing and/or separating filled sausage casings

Also Published As

Publication number Publication date
EP0282563A4 (en) 1989-09-04
EP0282563A1 (en) 1988-09-21
BE905400A (en) 1987-03-09
JPH01500813A (en) 1989-03-23
AU8031387A (en) 1988-04-07
AU598600B2 (en) 1990-06-28

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