GB2099751A - Heat sealing apparatus and method - Google Patents

Heat sealing apparatus and method Download PDF

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Publication number
GB2099751A
GB2099751A GB8213882A GB8213882A GB2099751A GB 2099751 A GB2099751 A GB 2099751A GB 8213882 A GB8213882 A GB 8213882A GB 8213882 A GB8213882 A GB 8213882A GB 2099751 A GB2099751 A GB 2099751A
Authority
GB
United Kingdom
Prior art keywords
plies
thermoplastics
seal
pair
bands
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.)
Withdrawn
Application number
GB8213882A
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.)
LIVERPOOL FINE ENGINEERING CO
Original Assignee
LIVERPOOL FINE ENGINEERING CO
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 LIVERPOOL FINE ENGINEERING CO filed Critical LIVERPOOL FINE ENGINEERING CO
Priority to GB8213882A priority Critical patent/GB2099751A/en
Publication of GB2099751A publication Critical patent/GB2099751A/en
Withdrawn legal-status Critical Current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
    • 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
    • B29C66/834—General aspects of machine operations or constructions and parts thereof characterised by the movement of the joining or pressing tools moving with the parts to be joined
    • B29C66/8341—Roller, cylinder or drum types; Band or belt types; Ball types
    • B29C66/83421—Roller, cylinder or drum types; Band or belt types; Ball types band or belt types
    • B29C66/83423—Roller, cylinder or drum types; Band or belt types; Ball types band or belt types cooperating bands or belts
    • 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
    • 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
    • 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
    • B29C66/81463—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 plurality of single pressing elements, e.g. a plurality of sonotrodes, or comprising a plurality of single counter-pressing elements, e.g. a plurality of anvils, said plurality of said single elements being suitable for making a single joint
    • B29C66/81465—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 plurality of single pressing elements, e.g. a plurality of sonotrodes, or comprising a plurality of single counter-pressing elements, e.g. a plurality of anvils, said plurality of said single elements being suitable for making a single joint one placed behind the other in a single row in the feed direction
    • 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
    • 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
    • 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
    • B29C65/24—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools characterised by the means for heating the tool
    • B29C65/30—Electrical means
    • B29C65/305—Electrical means involving the use of cartridge heaters
    • 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
    • B29C66/70—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
    • B29C66/70—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
    • B29C66/72—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 structure of the material of the parts to be joined
    • B29C66/723—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 structure of the material of the parts to be joined being multi-layered
    • B29C66/7232—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 structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer
    • B29C66/72327—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 structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer consisting of natural products or their composites, not provided for in B29C66/72321 - B29C66/72324
    • B29C66/72328—Paper

Landscapes

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

Abstract

A method for sealing plies of thermoplastics, has only two steps, namely applying heat and pressure at the line of the seal and subsequently compressing or crushing of the seal line. The preferred apparatus comprises a pair of juxtaposed endless metal bands 3, 5 between which the plies are gripped. The bands pass between two heating blocks 9.1, 9.2; 10.1, 10.2 which are resiliently biassed into heat conducting contact with the band. A pair of nip rollers 7 are disposed downstream of the heating blocks and outwardly of the endless band and crush the plies to form the seal. <IMAGE>

Description

SPECIFICATION Heat sealing machine and method The present invention relates to a method and apparatus for sealing together plies of material such as thermoplastics, especially polythene, cellophanes and laminates such as paper and polyethylene.
Apparatus is know for sealing plies of polyethylene. It comprises a pair of heating blocks between which the plies are compressed and heated at the line of the seal to fuse the plies together thereat and a pair of cooling blocks between which the plies are received directly from the heating blocks to cool the fused material and thereby form the seal.
In an embodiment of the present invention, the cooling blocks are omitted and the plies, after leaving the heating blocks, are passed through a nip to compress or crush the plies at the line of the seal. The temperature of the material at the seal line must not be sufficient to leave the material in a tacky condition as the plies pass through the nip. Consequently, the material at the seal line is substantially below its melting temperature on exit from the nip.
Thus, according to a first aspect of the present invention, there is provided apparatus for sealing plies of thermoplastics comprising at least one pair of heating blocks between which the plies are compressed and heated at the line of the seal and, separate from the heating blocks, nip means to compress or crush the plies at the line of the seal.
Thus, the embodiment entails only two steps, namely, applying heat and pressure at the seal line and then compressing or crushing of the seal line.
Thus, according to another aspect of the invention, there is provided a method of sealing plies of thermoplastics comprising the steps of applying heat and pressure at the line of the seal and subsequently compressing or crushing the plies of the line of the seal.
The heat and pressure step brings the material at the seal line to a plastic condition, and the subsequent compression thereof forms the seal. It has been found that by this means a very strong seal is formed.
A further advantage of the present invention is that it can also be used to seal cellophanes and laminates. Conventionally, these materials are heat sealed by radiated heat in order to avoid scorching of the material that might take place if a heating bar were impressed directly thereon.
However, since the present invention may employ a lower temperature than is conventionally used in sealing a material such as polyethylene, cellophanes and laminates may be sealed without danger of scorching.
In a preferred embodiment, two pairs of blocks are employed serially arranged as in a conventional machine used for sealing thermoplastics such as polyethylene, but in this instance, both pairs of blocks used are heating blocks. The blocks are arranged with a gap between the first pair of blocks and the second pair to permit a conventional gusseting attachment to be used. By this means, gusseted bags can be dealt with more efficaciously than would be the case with a single pair of blocks of the same total length. In such a machine, the material to be sealed is passed between the blocks of each pair of endless metal bands through which heat is conducted from the blocks to the material to be sealed. Such bands permit the temperature at the seal line to be closely controlled by adjustment of the temperature of the heating blocks.
It is also preferred to have total block length of some 21.6cm (82 inches). When using two pairs of blocks, the blocks of one pair need not be the same length as those of the other pair of blocks, for instance, the blocks of one pair could be some 10.16cm (4 inches) long and the blocks of the other pair some 11.43cm (4+ inches) long. A suitable separation between the two pairs of blocks is 2.54cm (1 inch).
It will be understood that the longer the block length, the greater is the dwell time of the material being sealed between the blocks for any given rate of feed of the material, and that the greater the dwell time, the less the block temperature needs to be. However, a compromise needs to be made between dwell time and temperature in order to avoid an unduly long dwell time, and the total block length given above has proved to be a practicable choice in this respect.
The invention will now be described, by way of example only, with reference to the accompanying drawing, which shows a diagrammatic front elevation of a sealing machine of the invention.
Referring to the drawing, the machine comprises a sheet material transport generally indicated at 1, and comprising two endless metal bands 3, 5 carried round respective pairs of pulley wheels 3-1, 3-2 and 5-1 and 5-2. The two endless bands are juxtaposed. At least one of the wheels of each pair is driven and on rotation drives the~band. The two bands are so arranged that the bottom run 3-3 of the top band 3 and the top run 5-3 of the lower band 5 are adjacent and form a nip, and the bands are driven to rotate in opposite senses, that is, the top one to rotate clockwise as viewed in the drawing and the bottom one to rotate counterclockwise as viewed in the drawing. An article to be sealed such as a bag is introduced into the nip at the right hand end thereof and is carried along in the nip until it exits at the opposite end of the nip.
In between the top and bottom run of each band, two serially arranged blocks are resiliently mounted to form two pairs of opposed blocks 9-1, 9-2 and 10-1, 10-2. Each block contains a heating element (not shown) and bears on the adjacent side of the respective endless band under resilient bias so that heat generated by the block is passed to the respective endless band and thus to the material being carried along in the nip. Because the bands conduct the heat to the material to be sealed, i.e. there is no radiation of heat, the temperature at the seal line of the material can be closely controlled by adjustment of the temperature of the heating blocks.
The rotation of the bands in any sealing operation is continuous and the dwell time of the material being sealed is determined by the speed of rotation and the overall length of the blocks, which in this instance is some 24.13cm (9- inches). However, the two pairs of blocks are separated by a distance of some 2.54cm (1 inch) and the total length of the blocks themselves is, therefore, some 21.6cm (86 inches); the first pair of blocks being some 10.16cm long and the second pair of blocks being some 11.43cm (4 inches) long.
Downstream of the exit end of the nip are located a pair of rollers 7, 7' forming a nip such as to cause compression of the material passed through the nip.
In use of the machine, the material, the plies of which are to be sealed, is passed into the transport 1 so that the bands lie on the line along which the seal is to be formed. The material thus positioned passes along the nip formed by the endless bands and is heated on that line to a plastic condition by the heat from the heating blocks while under pressure arising from the resilient bias of the heating blocks. When the material exits from the transport it passes directly to the compression rollers where the heated seal line is compressed and the seal formed. Since the compression rollers are not heated, they also act to cool the material passing through them.
If the material is one having gusset side folds, a pair of gusseting rollers may be mounted in the gap between the two pairs of heating blocks to make certain that the seal is formed in the part of the material lying between the gusset folds and especially in the transition from the four plies formed by the gusset folds to the two plies of the part of the material lying between the gusset folds.
The compression rollers may be adjusted in position to vary the clearance of the nip formed between them.
The word "Cellophane" is a registered Trade Mark.

Claims (15)

Claims
1. A method of sealing plies of thermoplastics comprising the steps of applying heat and pressure at the line of the seal and subsequently compressing or crushing the plies at the line of the seal.
2. A method as claimed in claim 1, in which the heat and pressure step brings the material at the line of the seal to a plastic condition and the subsequent compression forms the seal.
3. A method as claimed in claim 1 or 2, in which the heat is transferred to the thermoplastics material by conduction.
4. A method as claimed in claim 1, 2 or 3, comprising feeding the thermoplastic plies between at least one pair of heating elements and then between a pair of nip rollers.
5. A method as claimed in claim 4, comprising gripping the thermoplastics between adjacent faces of two juxtaposed endless metal bands which pass between the pair of heating elements, a respective one of the endless bands being contacted by a respective one of the heating elements.
6. Apparatus for sealing plies of thermoplastics comprising at least one pair of heating blocks between which the plies are compressed and heating at the line of the seal and, separate from the heating blocks, nip means to compress or crush the plies at the line of the seal.
7. Apparatus as claimed in claim 6, comprising a pair of juxtaposed endless metal bands which pass between the heating blocks, and between adjacent faces of which bands the thermoplastics is gripped.
8. Apparatus as claimed in claim 7, in which a respective one of the heating blocks is in heat conducting contact with a respective one of the bands.
9. Apparatus as claimed in claim 7 or 8 in which the endless bands are rotated in synchronism in counter-directions to feed the thermoplastics through the heating blocks and to the nip means.
10. Apparatus as claimed in any of claims 6 to 9, in which the nip means comprises a pair of counter-rotating juxtaposed compression rollers.
11. Apparatus as claimed in any of claim 6 to 10, in which two pairs of longitudinally spaced apart heating blocks are provided.
12. Apparatus as claimed in any of claims 6 to 11, in which each heating block is resiliently biased into contact with one or other of the endless bands.
13. A method as claimed in any preceding claim, in which the thermoplastics is polyethylene, or cellophane or laminates of paper and polyethylene.
14. A method of sealing plies of thermoplastics substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
15. Apparatus for sealing plies of thermoplastics constructed and arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawing.
GB8213882A 1981-05-13 1982-05-13 Heat sealing apparatus and method Withdrawn GB2099751A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8213882A GB2099751A (en) 1981-05-13 1982-05-13 Heat sealing apparatus and method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8114638 1981-05-13
GB8213882A GB2099751A (en) 1981-05-13 1982-05-13 Heat sealing apparatus and method

Publications (1)

Publication Number Publication Date
GB2099751A true GB2099751A (en) 1982-12-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8213882A Withdrawn GB2099751A (en) 1981-05-13 1982-05-13 Heat sealing apparatus and method

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0134901A2 (en) * 1983-07-26 1985-03-27 Reinhard Werner Leo Process for making a spirally wound article
US11230049B2 (en) * 2019-08-21 2022-01-25 Aerostar International, Inc. Seals for aerial vehicles

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0134901A2 (en) * 1983-07-26 1985-03-27 Reinhard Werner Leo Process for making a spirally wound article
EP0134901A3 (en) * 1983-07-26 1986-03-12 Reinhard Werner Leo Process for making a spirally wound article
US11230049B2 (en) * 2019-08-21 2022-01-25 Aerostar International, Inc. Seals for aerial vehicles
US12036724B2 (en) 2019-08-21 2024-07-16 Aerostar International, Llc Seals for aerial vehicles

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