GB1584644A - Creation of Inventions and Patents with Artificial Intelligence

GB1584644A – Method for manufacturing electric wire having wireenamel-type insulation
– Google Patents

GB1584644A – Method for manufacturing electric wire having wireenamel-type insulation
– Google Patents
Method for manufacturing electric wire having wireenamel-type insulation

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Publication number
GB1584644A

GB1584644A
GB613/80A
GB61380A
GB1584644A
GB 1584644 A
GB1584644 A
GB 1584644A
GB 613/80 A
GB613/80 A
GB 613/80A
GB 61380 A
GB61380 A
GB 61380A
GB 1584644 A
GB1584644 A
GB 1584644A
Authority
GB
United Kingdom
Prior art keywords
wire
bore
temperature
resin
melting point
Prior art date
1976-07-01
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.)

Expired

Application number
GB613/80A
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.)

Maillefer SA

Original Assignee
Maillefer SA
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.)
1976-07-01
Filing date
1977-06-27
Publication date
1981-02-18

1977-06-27
Application filed by Maillefer SA
filed
Critical
Maillefer SA

1981-02-18
Publication of GB1584644A
publication
Critical
patent/GB1584644A/en

Status
Expired
legal-status
Critical
Current

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Classifications

H—ELECTRICITY

H01—ELECTRIC ELEMENTS

H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES

H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables

H01B13/06—Insulating conductors or cables

H01B13/14—Insulating conductors or cables by extrusion

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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion

B29C48/06—Rod-shaped

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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/15—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor incorporating preformed parts or layers, e.g. extrusion moulding around inserts

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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/25—Component parts, details or accessories; Auxiliary operations

B29C48/30—Extrusion nozzles or dies

B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles

B29C48/335—Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular 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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/25—Component parts, details or accessories; Auxiliary operations

B29C48/30—Extrusion nozzles or dies

B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles

B29C48/34—Cross-head annular extrusion nozzles, i.e. for simultaneously receiving moulding material and the preform to be coated

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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/25—Component parts, details or accessories; Auxiliary operations

B29C48/96—Safety devices

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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/05—Filamentary, e.g. strands

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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/154—Coating solid articles, i.e. non-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

B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor

B29C48/16—Articles comprising two or more components, e.g. co-extruded layers

B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers

B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC

Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Y10S425/00—Plastic article or earthenware shaping or treating: apparatus

Y10S425/039—Pre-heat

Description

PATENT SPECIFICATION
( 11) 1 584 644 Application No 613/80 Divided out of No 1584642 ( 22) Filed 27 Jun 1977 ( 19) ( 31) Convention Application No 8446/76 ( 32) Filed 1 Jul 1976 in & ( 33) Switzerland (CH) ( 44) Complete Specification Published 18 Feb 1981 ( 51) INT CL 3 B 29 F 3/10 ( 52) Index at Acceptance B 5 A 1 G 11 1 G 1 l G 4 X 1 G 5 C 1 G 7 AX 1 G 7 C 1 G 8 A 1 G 8 B 1 G 8 C 1 R 214 A 1 R 214 E 1 R 314 C 12 1 R 314 C 1 A 1 R 314 C 1 S 1 R 314 C 1 X 1 R 314 C 6 1 R 439 E 2 C 2 D 1 X 2 H 4 2 M T 17 P ( 54) METHOD FOR MANUFACTURING ELECTRIC WIRE HAVING WIREENAMEL-TYPE INSULATION ( 71) We, MAILLEFER S A, a Company limited by shares duly organised under the Laws of Switzerland, of Ecublens, Canton of Vaud, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the follow-
ing statement:
This invention relates to a method for manufacturing electric wire having insulation of the wire-enamel type, wherein a high-melting-point synthetic resin is heated to a temperature at least as high as its melting-point, and a thin sheath of resin is formed about the wire.
What is called “insulated electric wire of the enamelled-wire type” is wire which is intended to be used in producing windings for electrical apparatus such as motors, transformers, magnetic coils, or other electrical components intended to operate under load conditions such that their temperature is higher than the ambient temperature For reasons of space-saving and economy, the sheath of insulating material covering such wire should be as thin as possible, while for reasons of durability and reliability, the insulating material should be stable at the operating temperature.
The requirements which must be met by such wire are laid down in certain standard specifications According to the German
Industrial Standards, for example, these requirements are set forth particularly in DIN Sheets 46435 and 46416.
The traditional method of manufacture utilized for wire having enamel-type insulation consists in preparing a solution of an 4 organic synthetic resin in a suitable solvent.
This liquid is placed in recipients through which the wire passes A film of liquid is then deposited on the surface of the wire.
This method requires a subsequent treatment operation to remove the solvent.
Moreover, it necessitates several successive passages of the wire through the bath of insulating material in order to obtain the required thickness of insulation Finally, the speed at which the wire travels is necessarily limited to a rate of the order of several meters per minute.
In order to avoid the drawbacks of this traditional system, especially the detrimental effects on the environment caused by the burning or evaporation of the solvent and the waste of energy involved in this operation, it has already been sought to replace the soluble resins used heretofore by synthetic materials capable of being heated without deterioration up to a temperature above that which the insulating material must withstand during operation According to German Disclosed Application (DOS) No.
2,135,157, the plastics material is contained in a bath heated to a temperature above the melting-point However, this method is delicate to carry out owing to the high temperatures required It is slow, and it also leads to waste of material when an operation must be interrupted, for the remainder of the material still contained in the recipient is then generally lost.
According to German Disclosed Application (DOS) No 2,022,802, a synthetic resin without solvent is introduced into an extruder, then forced into an extrusion unit.
The latter forms a tube of plastic material, thicker than the ultimate insulating layer, about the wire in the open air This tube leaves the extruder at a lower speed than that at which the wire travels through the extrusion unit The tube contracts on the wire as to cools and is subjected to drawing at the exit of the extrusion head The insulating material requires further treatment This method yields the thickness of insulation specified by the standards, i e, not exceeding about 15-34 microns, for example for a wire 1 mm in diameter hav( 21) ( 62) LI” c m) 1,584,644 ing a single layer of insulation For reinforced insulation, the standard thickness of the layer of insulating material is from 30 to 46 microns However, the insulated wire of the enamelled-wire type obtained in this manner is not uniform German Disclosed Application (DOS) No 2,110,934 also describes a method of the same type.
h It is known that for producing insulated wire intended for use in low-current installations, e g, telephone wire, it is customary to deposit a thermoplastic insulating material on gauged copper or aluminium wire in an extrusion operation by means of a unit which forms a sheath about the wire It has hitherto been thought that it was not possible to use such a unit for forming such thin sheaths as those required by the abovementioned standards, above all not if the insulating material was one having high thermal resistance.
According to the present invention, there is provided a method of manufacturing electric wire having insulation of the wireenamel type comprising the steps of working a thermo-plastic synthetic resin having a melting point of above 250 WC in a screw extruder whilst heating it to a temperature of at least 350 above its melting point, such that the molten resin acts as a truly hydrostatic liquid, feeding a wire to be insulated through a frusto-conical bore in an extrusion device in the direction of decreasing diameter of said bore, feeding said molten resin at said temperature to said bore under an inlet pressure of 10 1000 bar, whereby said resin in its passage through said bore is pressed against said wire under continuously increasing radial compression to form a molten coating thereon, and thereafter cooling the coated wire to solidify said coating Preferably, the resin is heated to a temperature of at least 40 WC above its melting point.
A preferred embodiment of the invention will now be described in detail with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic plan view of apparatus for carrying out the method according to the invention; Figure 2 is an elevation, on a larger scale, of a multiple extrusion head forming part of the apparatus of Figure 1; and Figure 3 is a side section, on a still larger scale of an extrusion unit fixed to the multiple extrusion head of Figure 2.
The apparatus illustrated in the drawings comprises a wire-drawer 1 an annealer 2 a multiple extrusion head 3 secured to the end of the cylinder of an extruder 4 driven by a motor 5 and a cooling vat 6 The apparatus as a whole is designed for the simultaneous treatment of four wires f conveyed parallel to one another through the various parts of the apparatus The wiresf may be of copper or aluminum and about 1 mm in diameter, for example They emanate from a pay-out installation (not shown) which supplies the wiredrawer 1 Upon leaving the cooling vat 6, the wires f are taken up by a withdrawal 70 mechanism and led onto reels (not shown).
The wiredrawer 1 may be of a conventional type having one or more stages It need not be described in detail here.
The annealer 2 is likewise of a type 75 known per se It will preferably be a resistance-type annealer having electrolyte contact devices Each wire f is thus guided by pulleys so as to follow a vertical path and passes through two pots which contain an 80 electrolyte and establish the contact between the wire and the current feed Between these pots, an electric current passes through the wire and heats it to annealing temperature The electrolyte ensures not 85 only good contact between the wire and the current feed but also pickling or descaling of the wire.
Immediately after the annealer 2, each of the four wires f passes through a respective 90 extrusion unit of the multiple head 3 so as to be coated with an insulating sheath at a temperature corresponding to that of the liquid insulating material forming that sheath The multiple head 3 is shown in gre 95 ater detail in Figures 2 and 3 It comprises at the top a distributor 7 through which there passes a horizontal duct 8 communicating with the outlet orifice of the extruder 4 The distributor duct 8 has four vertical branches 100 9 each of which passes through a body 10 of a respective displacement pump 11 rotatingly driven by an electric motor 12 Each motor 12 drives the associated pump 11 via a speed-reducer 13 and a coupling 14 The 105 pumps 11 are, for example, gear pumps.
The motor 12 and the speed-reducers 13 are secured to a pedestal 15 15 which is in turn fixed to a support 16 The bodies 10 of the pumps 11 may be combined into a single 110 unit secured beneath the distributor 7 and attached to the pedestal 15 Each pump 11 discharges into an outlet duct 17 extending vertically downwards within the body 10 and communicating with a respective extru 115 sion unit 18 The extrusion units 18 are situated in the paths of the wiresf, one of which passes axially through each unit 18.
The extrusion unit 18 shown in Figure 3 is composed of various parts assembled in 120 such a way as to be easily dismantled The unit 18 comprises a body 19 fixed beneath the pump body 10 by means of a flange 19 a; an inlet duct 20 passes through the top of the body 19 and communicates with the dis 125 charge duct 17 The duct 20 opens out into a frustoconical bore 21 the axis of which is horizontal in which bore there is disposed a die-holder 22, the outer side surface of which is likewise frustoconical and bears 130 1,584,644 against the bore 21 The die-holder 22 is of tubular form, in the frustoconical side surface of which there is an annular groove 23 which communicates with the duct 20 and serves to distribute the plastics material.
The two ends 22 a and 22 b of the die-holder 22 are threaded and intended to receive, respectively, a check-nut 24 for holding an extrusion die 25 on the downstream end 22 b and a nut 26 for securing the die-holder 22 to the body 19 at the upstream end 22 a The interior of the die-holder 22 has at its downstream end a cylindrical bore 27 in which the extrusion die 25 is fitted, in the middle a frustoconical bore 28 which holds and centers a guiding die 29, and at the upstream end a cylindrical bore 30, the diameter of which corresponds to that of the smallerdiameter end of the frustoconical bore 28 A series of oblique holes 31 are drilled in the die-holder 22 between the bottom of the groove 23 and the zone where the bore 27 joins the bore 28 Through the holes 31, the plastics material discharged into the duct 20 reaches the space bounded by the bore 27 and the extrusion and guiding dies 25 and 29 situated one behind the other within the die-holder 22 This space constitutes a distribution chamber which feeds the die 25.
The dies 25 and 29 are high-precision parts.
The central passage way of the die 29 contains a diamond ring-gauge 32 secured by means of a pierced cap 33 and having a central aperture matching the wire f in diameter The down-stream face of the die 29 is of frustoconical shape; the side surface thereof is cylindrical and faces the bore 27; the down-stream face of the pierced cap 33 is plane and perpendicular to the axis of its central passageway.
The die 25 comprises, on the upstream side thereof, an entry cone 34, the surface of which is substantially parallel to the downstream face of the die 29 and which bounds, together with the latter, an annular zone of the aforementioned distribution chamber, the outer diameter of which zone varies gradually and is so calculated that the plastics material will be gradually accelerated as it moves towards the axis of the unit The inner end of the entry cone 34 of the die 25 joins a compression cone 35 which bounds the central passageway of the die 25 and joins a cylindrical bore 36 extending up to the downstream end of the die 25.
It has been found that the dimensioning of the die 25 plays a very important part in obtaining the desired result The frustoconical bore 35 forming the compressing means must have an aperture angle a of between 2 and 20 as the case may be the angle preferably being 7 for the materials used in the present invention, while the diameter of the cylindrical bore 36 will be equal to the outside diameter of the insulating sheath to be deposited on the wire f This diameter will therefore be slightly greater than that of the wire f; the difference can vary from about 10 microns to about 100 microns depending upon the characteristics desired 70 for the insulated wire and required by the standards The length L, which represents the distance between the exit of the extrusion die 25 and the exit of the guiding die 29, also plays a large part in obtaining the 75 desired result The length L may vary from 4 mm to 40 mm depending upon the application Finally, the die 25 will preferably be made of sintered hard metal (tungsten carbide), and its inner faces which are in con 80 tact with the plastic material will exhibit a mirror-polish surface condition preferably obtained by an electrolytic polishing operation.
As has already been stated above, the 85 extruder 4 is a screw extruder, the cylinder of which contains a single screw and which is driven by the motor 5 at a variable speed.
The extruder 4 is equipped with regulating means comprising a pressure detector 37 90 connected to the outlet of the extruder and a regulator 38 which controls the speed of the motor 5 This arrangement controls the flow of plastics material and keeps the pressure constant at the outlet of the extruder 4 The 95 motors 12 driving the pumps 11 are likewise controlled by regulating devices, each comprising a pressure detector 39, responsive to the pressure prevailing in the duct 20, and a regulator 40 controlling the speed of the 100 motor 12 Thus there is obtained a flow of plastics material which is controlled at a constant value and which reaches the dieholder 22 at a pressure which is likewise constant 105 As concerns the temperature conditions, these, too, must be very precisely controlled For this purpose, both the cylinder of the extruder and the extrusion head may be provided with heating elements Thus the 110 body 19 of the extrusion unit 18 illustrated in Figure 3 bears a heating element 41.
Temperature sensors may be mounted in the extrusion units 18 as well as in the distributor and the outlet of the cylinder of the 115 extruder 4, these temperature sensors controlling the heating elements 41 so that the temperature of the plastics material is maintained at the required levels at the various points of the apparatus In certain cases, the 120 die may also be provided with a heating element 42; Finally, in order to obtain good results, the speed of each of the wires f should correspond constantly to that of the flow of 125 plastics material if the insulating sheath is to be deposited uniformly on the wire Thus the flow-regulating device made up of the elements 37 38 39 40 may be controlled by the speed of travel of the wire f and, 130 1,584,644 consequently, by the operating speeds of the withdrawal mechanism and of the wiredrawer 1.
It should be noted that it is not absolutely necessary to interpose a displacement pump such as the pump 11 between the cylinder of the extruder 4 and the extrusion unit 18 In the case of apparatus treating only one wire, for example, this pump could be eliminated.
However, in the case of apparatus treating a plurality of wires in parallel, the presence of the pumps 11 provides several additional advantages It is possible to regulate the flow into the various extrusion units 18 independently of one another and, consequently, to work with different units and treat wires of different diameters in parallel.
Moreover, these pumps make it possible to block one of the lines while still allowing the others to operate For instance, in the event of breakage of a wire in the wiredrawer, the corresponding pump may immediately be cut off by a detector safety device Since it is a displacement pump, it then acts as a stop gate which closes The pressure in the distributor duct 8 is maintained, and the other extrusion units can continue to operate while the unit corresponding to the broken wire is dismantled and put back in order.
A more specific description will now be given of the operating conditions which enable the production, in accordance with the invention using the apparatus described above, of enamel-insulated wire answering the Specifications of DIN standards 46416 ff., especially 46435 and 46453.
The first requirement to be met in order to produce wire resistant to the specified maximum temperatures (type W 180) is that the insulation must withstand a temperature of 2650 C without breakdown For this purpose, certain partially crystalline thermoplastic polycondensates, wherein the melting-point of a crystalline elements is above 170 ‘C, or preferably even 250 ‘C, may be used as insulating material Certain known products such as polyethylene terephthalate (PETP), 66-polyamide or polyphenyl sulfide, meet these requirements These are very high melting-point thermoplastic products which may be introduced into the hopper of the extruder in the form of pellets, powder or a conglomerate.
The mixing of these products in the extruder raises their temperature to above their softening-point The heating elements with which both the cylinder of the extruder 4 and the extrusion head 3 are equipped then make it possible to increase the temperature still further Thus the temperature control permits gradually reaching a temperature of about 320 WC in the extrusion unit 1 8 when the material used is polyethylene terephthalate (melting-point 2560 C) about 290 WC with 66-polyamide (melting-point 2550 C).
and about 320-3400 C with certain products having a melting-point of 280 ‘C Hence the plastics material reaches the extrusion unit in a state which is appreciably above its melting-point, so that it behaves as a truly 70 hydrostatic fluid.
It has been found that it is necessary to exert upon this fluid pressure amounting to from 10 to 1,000 bars, as the case may be.
Preferably, however, this pressure will be at 75 least 60 bars, the pumps 11 preferably providing a compression ratio of 1:2, the pressure at the outlet of the extruder thus being half the final pressure It will be noted that this pressure is maintained in the chamber 80 situated between the extrusion die and the guiding die owing to the particular configuration of the passageway of the extrusion die and especially owing to the cone 35, the dimensions of which will therefore be 85 selected accordingly.
As has already been stated above, the speed of travel of the wire f constitutes the initial value which controls the operation of the apparatus, and particularly the output of 90 the extruder Whereas in apparatus utilizing a bath, the speed of travel of the wire is limited to a few meters or a few dozen meters per minute, it has proved possible when using apparatus such as is described above 95 to vary the speed of travel of the wire from about 20-50 m /min up to speeds on the order of 300-500 m /min depending upon the products used Owing to the shape of the distribution chamber situated within the 100 extrusion unit, the plastics material is pulled along by the wire inside the compressing means 35 and into the passageway 36 so that it is subjected to very strong radial pressure when passing through the die As a 105 result the wire is kept perfectly centered in the passageway 36 on the one hand, and the plastics material forms a compressed and compact sheath upon the wire, on the other hand With the precision unit described 110 above, it has been possible to produce insulation about 20-50 microns thick on wire from 0 6 to 1 mm in diameter and a hardness of from 1 H to 3 H (DIN 45453).
With products mentioned above, simple 115 cooling suffices to give the insulating sheath its definitive structure As a variation, curing treatments such as exposure to beta or gamnma-rays may additionally be utilised.
The use of the thermoplastic materials 120 mentioned above by way of example for the insulation of electric wires is described in co-pending Application No 26783/77 (Serial No 1584643) in the name of one of the present applicants Maillefer S A in which 125 Application contains details of numerous examples of such thermoplastic materials.

Claims (8)

and which Claims a method of manufactur- ing electric wire of the enamelled wire type comprising the steps of extruding a solvent 130 1,584,644 free thermoplastic material comprising at least one partially crystalline thermoplastic polycondensate comprising crystallites having a melting point above 170 TC at a temperature at or above the crystalline melting point of said thermoplastic polycondensate in said material onto and around a metal wire so as to form on said wire an electrically-insulating sheath having a thickness in accordance with the requirements of German Industrial Standard DIN 46435 in respect of the metal wire used. Other thermoplastic products than those of Application No 26783/77 (Serial No. 1584643) may, however, equally well be used in the method of the present invention. A plurality of such products may, if desired, he used in admixture, and it is possible to add additives to the products, e g dye pigrrients, or resins facilitating flow in the extrusion unit. Generally speaking, the method of the present invention is particularly suitable for wire having a metal core between 0 1 and 4 0 mm in diameter (Serial No 1584642). Our Co-pending Application 26780/77 claims apparatus for manufacturing electric wire having insulation of the wire-enamel type. WHAT WE CLAIM IS:

1 A method of manufacturing electric wire having insulation of a wire-enamel type comprising the steps of working a thermoplastic synthetic resin having a melting point of above 250 WC in a screw extruder whilst heating it to a temperature of at least 350 above its melting point, such that the molten resin acts as a truly hydrostatic-liquid, feeding a wire to be insulated through a frustoconical bore in an extrusion device in the direction of decreasing diameter of said bore, feeding said molten resin at said temperature to said bore under an inlet pressure of 10 1000 bar whereby said resin in its passage through said bore is pressed against said wire under continuously increasing radial compression to form a molten coating thereon, and thereafter cooling the coated wire to solidify said coating.

2 A method as claimed in Claim 1, wherein said resin is heated to a temperature at least 40 WC above its melting point.

3 A method as claimed in Claim I or Claim 2, wherein said molten resin is fed to said frustoconical bore under an inlet pressure of at least 60 bar.

4 A method as claimed in any one of Claims l to 3 wherein the diameter of said wire is 10 to 100 1 úm smaller than the smallest diameter of said bore.

A method as claimed in any one of the preceding Claims, wherein the flow of said molten resin forced into said extrusion device is controlled as a function of the speed at which said wire is passed through said bore.

6 A method as claimed in any one of the preceding Claims, wherein said wire is subjected to an annealing treatment in tandem before it enters said extrusion device 70

7 A method as claimed in any one of the preceding Claims, wherein said resin is caused to leave said extrusion device at a speed equal to that of said wire.

8 A method as claimed in Claim 1 of 75 manufacturing electric wire having insulation of the wire-enamel type, substantially as hereinbefore described, with reference to the drawings.
For the Applicants 80 G.F REDFERN & CO.
Chartered Patent Agents Marlborough Lodge 14 Farncombe Road Worthing 85 West Sussex BN 11 2 BT.
Printed for Her Majesty’s Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey 1981.
Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

GB613/80A
1976-07-01
1977-06-27
Method for manufacturing electric wire having wireenamel-type insulation

Expired

GB1584644A
(en)

Applications Claiming Priority (1)

Application Number
Priority Date
Filing Date
Title

CH844676A

CH612789A5
(en)

1976-07-01
1976-07-01

Publications (1)

Publication Number
Publication Date

GB1584644A
true

GB1584644A
(en)

1981-02-18

Family
ID=4340481
Family Applications (2)

Application Number
Title
Priority Date
Filing Date

GB26780/77A
Expired

GB1584642A
(en)

1976-07-01
1977-06-27
Rapparatus for manufacturing electric wire having wire-enamel-type insulation

GB613/80A
Expired

GB1584644A
(en)

1976-07-01
1977-06-27
Method for manufacturing electric wire having wireenamel-type insulation

Family Applications Before (1)

Application Number
Title
Priority Date
Filing Date

GB26780/77A
Expired

GB1584642A
(en)

1976-07-01
1977-06-27
Rapparatus for manufacturing electric wire having wire-enamel-type insulation

Country Status (13)

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US
(2)

US4165957A
(en)

JP
(1)

JPS5811046B2
(en)

AT
(1)

AT359575B
(en)

BR
(1)

BR7704319A
(en)

CH
(2)

CH612789A5
(en)

DE
(1)

DE2728883B2
(en)

ES
(1)

ES460231A1
(en)

FR
(1)

FR2357042A1
(en)

GB
(2)

GB1584642A
(en)

IN
(1)

IN149498B
(en)

IT
(1)

IT1079874B
(en)

NL
(1)

NL7707320A
(en)

SE
(1)

SE458973B
(en)

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Publication date
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GB2133737A
(en)

1983-01-15
1984-08-01
Plessey Co Plc
Improvements relating to the manufacture of magnetic sensing optical devices

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CROSS-HEAD FOR CABLE SHEATHING.

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Extrusion of a plastic coating about a strand

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Northern Telecom Limited
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Preparing magnet wire having electron beam curable wire enamels

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1984-08-22
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Blanyer Richard J
Method and apparatus for coating a core material with metal

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1986-07-29
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FLAT HEAD FOR THE EXTRACTION OF THERMOPOLASTIC MATERIALS IN SHEET AND LEAF, PROVIDED WITH TWO OR MORE CONDUITS, FOR FEEDING THE SAME MATERIALS

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Co-extrusion head for coating wire

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Breathable film and manufacturing method

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1976

1976-07-01
CH
CH844676A
patent/CH612789A5/xx
not_active
IP Right Cessation

1977

1977-06-23
IN
IN942/CAL/77A
patent/IN149498B/en
unknown

1977-06-27
DE
DE2728883A
patent/DE2728883B2/en
not_active
Ceased

1977-06-27
GB
GB26780/77A
patent/GB1584642A/en
not_active
Expired

1977-06-27
GB
GB613/80A
patent/GB1584644A/en
not_active
Expired

1977-06-28
AT
AT457577A
patent/AT359575B/en
active

1977-06-29
US
US05/811,362
patent/US4165957A/en
not_active
Expired – Lifetime

1977-06-29
FR
FR7719997A
patent/FR2357042A1/en
active
Granted

1977-06-29
ES
ES460231A
patent/ES460231A1/en
not_active
Expired

1977-06-30
SE
SE7707626A
patent/SE458973B/en
not_active
IP Right Cessation

1977-06-30
IT
IT50067/77A
patent/IT1079874B/en
active

1977-07-01
BR
BR7704319A
patent/BR7704319A/en
unknown

1977-07-01
NL
NL7707320A
patent/NL7707320A/en
not_active
Application Discontinuation

1977-07-01
JP
JP52077957A
patent/JPS5811046B2/en
not_active
Expired

1979

1979-02-09
CH
CH130379A
patent/CH620787A5/fr
not_active
IP Right Cessation

1980

1980-11-06
US
US06/204,755
patent/US4379102A/en
not_active
Expired – Lifetime

Cited By (1)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

GB2133737A
(en)

1983-01-15
1984-08-01
Plessey Co Plc
Improvements relating to the manufacture of magnetic sensing optical devices

Also Published As

Publication number
Publication date

NL7707320A
(en)

1978-01-03

ES460231A1
(en)

1978-04-16

SE7707626L
(en)

1978-01-02

DE2728883A1
(en)

1978-01-05

SE458973B
(en)

1989-05-22

GB1584642A
(en)

1981-02-18

US4379102A
(en)

1983-04-05

JPS5811046B2
(en)

1983-03-01

IN149498B
(en)

1981-12-26

AT359575B
(en)

1980-11-25

CH612789A5
(en)

1979-08-15

JPS534874A
(en)

1978-01-17

BR7704319A
(en)

1978-04-18

DE2728883B2
(en)

1979-07-12

US4165957A
(en)

1979-08-28

CH620787A5
(en)

1980-12-15

ATA457577A
(en)

1980-04-15

IT1079874B
(en)

1985-05-13

FR2357042A1
(en)

1978-01-27

FR2357042B1
(en)

1982-12-10

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