APPARATUS AND METHOD FOR PREPARING FLAME-PROOF FLAT CABLES

Abstract: A flame-proof flat cable according to the present invention has a structure of laminating a plurality of conductors as needed with two films, a bottom film and a top film, of PTFE or PTFP. The conductors may be coated with a PTFE or PTFP resin material. The laminating surfaces of the bottom and top films are laminated with a fluorinated ethylene propylene (FEP) film in order to give a good contacting ability when the bottom and top films are laminated. A method of preparing a flame-proof flat cable according to the present invention comprises feeding a plurality of conductors from a rack to a laminator, preheating the conductors through a pair of core-heaters at a temperature of 260 to 659 DEG C (500 to 1200 DEG F), feeding a bottom film below the conductors and a top film over the conductors between a lower infrared heater and an upper infrared heater and between a lower shoe heater and an upper shoe heater, laminating the conductors with the bottom film and the top film by a lower heating roll and an upper heating press roll to form a laminated flat cable, and cooling the laminated flat cable by a cooling system having a pair of cooling rolls.

Description: APPARATUS AND METHOD FOR PREPARING FLAME-PROOF FLAT CABLES Field of the Invention The present invention relates to a flameproof flat cable, an apparatus for manufacturing the flameproof flat cable and a method of preparing the flameproof flat cable. More particularly, the present invention relates to a flameproof flat cable in which a plurality of conductors are laminated between two polytetrafluoroethylene (PTFE) films and which are used in VCRs, camcoders, computers, rockets, missiles, automobiles, ships, aircraft, and optical communication. Background of the Invention Many electrical or mechatronic apparatuses have been used in all of the industries. Particularly, various electrical or mechatronic apparatuses are used in VCRs, camcoders, computers, rockets, missiles, automobiles, ships, aircraft, and optical communication equipments, which need absolutely many cables. Flat cables used in electrical or mechatronic apparatuses are prepared by laminating a plurality of conducting wires (hereinafter "conductors") with synthetic resin films. In other words, conventional flat cables for electrical or mechatronic apparatuses are prepared by laminating a plurality of conductors such as 20, 40 or 120 conductors in a flat type with two synthetic resin films such as a bottom film and a top film. Flat cable which laminates conductors with a synthetic resin film is also called as "conductor ribbon cable". In the conventional flat cables, polyester films are used for lamination of conductors. The melting point of polyester is relatively low. Accordingly, the conventional flat cables can be easily damaged in event of fire, furthermore, this damage can cause a serious problem on the electrical or mechatronic apparatuses. Sometimes, the damaged apparatuses are not repaired or recovered. In particular, in case of fire of a communication system, a communication blackout can occur to cause a serious damage. Therefore, there is a need to develop a flame-resistant flat cable for use of state-of-the-art electrical or mechatronic equipments. Polytetrafluoroethylene (PTFE) and polytetrafluoropropylene (PTFP) are known having an excellent flameproof property. The PTFE and PTFP are flame-resistant even at about 800 °F and are not melt at the high temperature. If a flat cable is laminated with PTFE or PTFP, the flat cable can be safely maintained without any damages, in case of fire. The PTFE and PTFP are sold by Dupont Company of U.S.A. under their registered trademarks (Teflon or Kapton). However, a technique of laminating a plurality of conductors with PTFE or PTFP films has not been developed. The present inventor has developed an apparatus for manufacturing a flameproof flat cable which laminates conductors with PTFE or PTFP films and a method of preparing the flameproof flat cable. Objects of the Invention An object of the present invention is to provide a flameproof flat cable for use of state-of-the-art electrical or mechatronic equipments. Another object of the present invention is to provide a flameproof flat cable for use of state-of-the-art electrical or mechatronic equipments, which is prepared by laminating a plurality of conductors with PTFE or PTFP films, thereby having a flame -re si stance even at 800 °F A further object of the present invention is to provide an apparatus for manufacturing a flameproof flat cable which is prepared by laminating a plurality of conductors with PTFE or PTFP films. A still further object of the present invention is to provide a method of preparing a flameproof flat cable which is prepared by laminating a plurality of conductors with PTFE or PTFP films. Summary of the Invention A flameproof flat cable according to the present invention has a structure of laminating a plurality of conductors as needed with two films, a bottom film and a top film, of PTFE or PTFP. The conductors may be coated with a PTFE or PTFP resin material. The laminating surfaces of the bottom and top films are laminated with a fluorinated ethylene propylene (FEP) film in order to give a good contacting ability when the bottom and top films are laminated. A method of preparing a flameproof flat cable according to the present invention comprises feeding a plurality of conductors from a rack to a laminator, preheating the conductors through a pair of core-heaters at a temperature of 500 to 1200 °F, feeding a bottom film below the conductors and a top film over the conductors between a lower infrared heater and an upper infrared heater and between a lower shoe heater and an upper shoe heater, laminating the conductors with the bottom film and the top film by a lower heating roll and an upper heating press roll to form a laminated flat cable, and cooling the laminated flat cable by a cooling system having a pair of cooling rolls. An apparatus for manufacturing a flameproof flat cable according to the present invention comprises a rack for supporting a plurality of spools for winding conductors; means for preheating the conductors at a temperature of 500 to 1200 °F; a feeding system of a bottom film and a top film, including a pair of infrared heaters and a pair of shoe heaters, a laminator for laminating the conductors with the bottom film and the top film, including a lower heating roll and an upper heating press roll; means for cooling the laminated flat cable; means for slitting the laminated flat cable having a predetermined number of conductors, means for drawing the slit flat cables, and means for winding the slit flat cables. Brief Description of the Drawings The present invention will be more fully understood by reference to the following detailed description of the preferred embodiment of the present invention when read in conjunction with the accompanying drawings. Fig. 1 is a schematically perspective view of a rack for supporting a plurality of spools for winding conductors to feed to a laminator for manufacturing a flameproof flat cable; Fig. 2 is a schematic front view of a laminator for manufacturing a flameproof flat cable according to the present invention; Fig. 3 is a schematically perspective view of a flameproof flat cable according to the present invention; and Fig. 4A to 4F are cross- sectional views of flameproof flat cables according to preferred embodiments of the present invention. Detailed Description of the Preferred Embodiments A flat cable of the present invention is schematically illustrated in Fig. 3. The illustrated flat cable in Fig. 3 is one of the embodiments according to the present invention, which has a laminated structure having PTFE films 11, 12 laminated with FEP in upper and lower parts individually on the plane- aligned conductors 1 which are coated with PTFE. More particularly, PTFE film consists of a layer of PTFE and a layer of FEP. A layer of PTFE has a thickness of about 3 μm and a layer of FEP has a thickness of about 2 μm. The layers of PTFE and FEP are laminated by a heat adhesion. The reason of laminating FEP layer to PTFE layer is that the FEP layer shows a good adhesion by means of heating and pressing, that is, a plurality of conductors are aligned between PTFE films, and a FEP layer sticks to both of conductors and a PTFE layer. Although the number of conductors of a flat cable is a variable number such as 20, 40, 120, etc., it can be manufactured by the present invention in accordance with a use for a certain purpose. The plan views of flat cables are very various, and a couple of a model of the plan view of the embodiment is illustrated in Fig. 4. According to the present invention, a method and an apparatus for preparing a flat cable are like as following. Fig. 1 and Fig. 2 illustrate the wire dispensing rack and the laminator individually, which are apparatuses operating continuously. Fig. 1 is a schematically perspective view of the wire dispensing rack to supply conductors to the laminator for manufacturing a flameproof flat cable. Spools which are wound with conductors 1 are installed in the wire dispensing rack to supply conductors 1. The supplied conductors 1 from the spools are decided by sensors 2 whether cut or not. That is, if any one of conductors 1 is cut during a work, an operation of machine is stopped by sensors 2. Conductors 1 passing through sensors 2 are aligned as passing through guide rolls 3 and comb type rolls 4, 5. After conductors 1 passing through the comb type roll 5 pass through the motorized feed roller 6, they are supplied to the laminator showed in Fig. 2. The wire dispensing rack of Fig. 1 shows only forty spools 1. Installing more than that value is available. Fig. 2 is a schematic front view of the laminator for manufacturing a flameproof flat cable according to the present invention; A plurality of plane- aligned conductors 1 pass through comb/guide roller 10, and feed to between the core heaters 13. A pair of core heaters 13 are heated in the range of 500 ~ 1200°F, and preheat conductors 1. A purpose of preheating is to laminate a PTFE film in the next step and to prevent bubbles creation between films when laminating PTFE film on the conductors. A top film 11 which is laminated on the top surface of plane-aligned wires passes through an apparatus of heating and pressing after passing IR heater 14 and shoe heater 16 through the guide roll 10. A bottom film 12 which is laminated on the top surface of plane-aligned wires passes through an apparatus of heating and pressing after passing IR heater 14 and shoe heater 16 through the guide roll 10. IR heaters 14, 15 and shoe heaters 16, 17 play a role to be able to laminate smoothly by preheating the top and bottom films 11, 12. The top and bottom films comprise layers of PTFE and FEP, and a thickness of a layer of PTFE is about 3 μm and a thickness of a layer of FEP is about 2 μm. A layer which adhere to the plane- aligned wires 1 is a layer of FEP, and the outer surface is a layer of PTFE. The reason why a layer of FEP shall be an adherent layer is to keep a strong adhesion. In heating and pressing apparatus 50, the top and the bottom heating rolls 18, 19 laminate the films on the conductors as heated at a temperature in a specific use of the flat cable. The bottom heating roll 19 is fixed, and the top heating roll 18 presses the flat cable by means of a laminator roll pressure system 20. The cross section of the flat cable is various as showed in Fig. 4A to 4F. The portions of containing conductors 1 among the cross sections have a thick thickness as much as a height, and the portions without conductors, in which the top and the bottom films 11, 12 adhere directly, have a thin thickness. In order to laminate in these forms, slip sheet which has a form of cross section is used. The slip sheet 35 from the pay-out roll 31 winds along the top heating roll 18 to the take-up roll 32 to press the top film 11. The slip sheet 35 from the pay-out roll 33 winds through the bottom heating roll 19 to the take-up roll 34. The plane- aligned conductors 1 are completed the lamination by the top and the bottom films 11, 12, and go to the cooling system 60. There are two cases in a cooling system that one case cools down through the cooling rolls 21, 22, and another case cools down through the cooling roll 22 after cooling down through the cooling roll 30 of the chilled water tank 70 after passing through the cooling roll 22. After a flat cable passes through the cooling roll 22 in the cooling system 60, both edges of films, which is called "scrap" hereafter, is wound up by a scrap cable spool 24, and individual flat cables are cut, and pass through puller rolls 25, and takes up to a cable wind-up arbor 26. The scraps is slit into strips by a rotary slitter 23 of a cutting system, and individual flat cables is slit into strips. That is, in case that a flat cable comprises twenty conductors, it can be slit to form twenty conductors of a flat cable by a rotary slitter 23 after laminating 40, 60, 80, 100 and 120 wires in accordance with the apparatus of the present invention. Fig. 1 and Fig. 2 illustrate about supporting forty conductors 1 and making a flat cable contained twenty conductors in which two flat cables, slit by a rotary slitter 23, are wound to the cable wind-up arbor 26. The top film 11 and the bottom film 12 prefer to be removed moisture in an oven before feeding to IR heater 14, 15. The oven 100 prefers to keep a temperature of 250°F. Fig. 4 A to 4F are schematic views of cross -sections of flat cables according to the present invention. Fig. 4 A is a cross -sectional view of a flat cable, laminating a plurality of uncoated wires with PTFE film to the top and the bottom. Fig. 4B is a cross- sectional view of a flat cable, laminating a plurality of coated wires 1 with PTFE film to the top and the bottom. Fig. 4C is a cross- sectional view of a flat cable, laminating with PTFE film to the portion of the top and the bottom to be one unit in each two wires 1 which is coated with PTFE. Fig. 4D is a cross -sectional view of a flat cable, laminating with PTFE film to the portion of the top and the bottom to be one unit in each two wires 1, coated with PTFE, and a grounding conductor. Fig. 4E is a cross- sectional view of a flat cable, laminating with PTFE film to the portion of the top and the bottom to be one unit in each three wires 1, coated with PTFE. Fig. 4F is a cross- sectional view of a flat cable, laminating with PTFE film to the portion of the top and the bottom to be one unit in aligned four bare wires 1. The present invention shows the effect to manufacture a flameproof flat cable having a high flame-resistance, laminating a plurality of conductors with PTFE film for a use of state-of-the-art electrical or mechatronic equipments, etc. The present invention can be easily carried out by an ordinary skilled person in the art. Many modifications and changes may be deemed to be with the scope of the present invention as defined in the following claims.

Claims: What is claimed is: 1. A flameproof flat cable comprising a structure of laminating a plurality of conductors as needed with two films, a bottom film and a top film, of PTFE or PTFP, wherein said films have 30 μm as a thickness of a layer of PTFE or PTFP which is laminated with a fluorinated ethylene propylene (FEP) film to give a good adhesion and 2 μm as a thickness of a layer of the fluorinated ethylene propylene (FEP) film. 2. A method of preparing a flameproof flat cable comprising the steps of: feeding a plurality of coated or uncoated conductors 1 with PTFE or PTFP from a wire dispensing rack to a laminator; preheating conductors 1 through a pair of core heaters 13 to prevent a bubble creation before supplying to the heating and pressing system; supplying PTFE or PTFP films 11, 12 through IR heaters 14, 15 and shoe heaters 16, 17 individually to the upper-lower of conductors 1 to adhere a layer of fluorinated ethylene propylene (FEP) by heating and pressing; laminating said conductors 1 and said films 11, 12 by a lower heating roll 19 and an upper heating press roll 18 at 800°F; cooling the laminated flat cable by cooling rolls 21, 22; slitting the cooled flat cable by the rotary slitter 23 according to a predetermined number of conductors; and winding individual flat-cables, which is pulled by puller rolls, in the cable wind-up arbors 26. 3. The method according to claim 2 wherein said conductors 1 supplied from a wire dispensing rack are supplied through a sensor 2, a guide roller 3, a comb type roller 4, 5 and a motorized feed roller 6. 4. The method according to claim 2 wherein said a upper heating roll 18 is pressed by a laminator roll pressure system 20. 5. The method according to claim 2 wherein a slip sheet 35 passes said upper heating roll 18 along the surface thereof, and a slip sheet 35 passes said lower heating roll 19 along the surface thereof. 6. The method according to claim 2 wherein said flat cable passing said cooled roll 21 passes a cooling roll 30 of a chilled water tank 70 and passes a cooling roll 22. 7. The method according to claim 2 wherein further includes the step of drying said films 11, 12 in an oven 100 at a temperature of 250°F prior to suppling said films 11, 12 to an IR heaters 14, 15.

Inventors: LEE JONG CHAN, LEE, JONG, CHAN
Applicants: KOREA HIGH TECH CO LTD, LEE JONG CHAN, KOREA HIGH TECH CO., LTD., LEE, JONG, CHAN
Application year: 1997
Main classification: H01B7
IPC codes: B32B27, H01B7, H01B13