GB2112710A

GB2112710A - Apparatus and procedure for printing on round plastics tubing

Info

Publication number: GB2112710A
Application number: GB08134143A
Authority: GB
Inventors: William John Harrison
Original assignee: Bowthorpe Hellerman Ltd
Current assignee: Bowthorpe Hellerman Ltd
Priority date: 1981-11-12
Filing date: 1981-11-12
Publication date: 1983-07-27

Abstract

Method and apparatus for forming a printed sleeve for fitting over the end of an insulated wire in which the tube 26 is collapsed by external pressure, heated and then cooled to set the tube in a flattened condition before it is passed through a printer 39. The printed sections are then cut to length at 45 or the long length of the tube may be partially severed to allow the different sections to be removed. The apparatus typically comprises a first fluid chamber 14 containing fluid at an elevated temperature, a second chamber 12 containing cool fluid and a passage between the two chambers at a low level so that plastics tubing passing through the first chamber and thence through the second chamber has to pass through a region of high hydrostatic pressure which causes the wall of the tube to collapse. Water may be used on the fluid, but preferably a low melting point metal, such as mercury or a halogenated hydrocarbon fluid may be employed. <IMAGE>

Description

SPECIFICATION Apparatus and procedure for printing on round plastics tubing This invention concerns apparatus and procedures for printing on tubes of plastics material. The invention allows tubular plastics sleeves to be formed having printing or other markings thereon for identification purposes.

The marking of cables in a cable harness of a motor vehicle or an aeroplane or ship is a tedious process and it has been proposed to identify the ends of a multiple element cable harness or the like with slip-on sleeves of plastics or rubber material.

Each of the sleeves is marked by printing or otherwise so that the complete set of names or identifying symbols etc., is available so that the procedure is vertically self checking. As each end of a cable harness is formed so the approporiate sleeve is fitted to the end of the cable concerned and all of the cables are then reliably identified to allow for servicing maintenance and checking procedures later.

The present invention provides an improved method of forming a marked sleeve of plastics material.

According to one aspect of the present invention a method of forming a printed sleeve for fitting over the end of an insulated wire forming part of a cable harness comprises steps of:1. Continuous moving a long or endless length of round section tubing into a first zone in which the tube wall is heated to a first elevated temperature.

2. Increasing the external pressure acting on the wall of the tube to cause the latter to collapse and form a flat section tube.

3. Causing the flattened sectioned tube to move into a second cooler zone where the reduced temperature causes the plastics material to set in the flattened condition, 4. Either in said second zone or after the material has passed through the second zone, reducing the pressure acting on the external surfaces of the tube to normal atmospheric pressure.

5. Causing the tube to pass to a printer at which indicia such as letters numerals etc., are imprinted or otherwise marked onto the flattened surface and 6. Cutting the length of flattened tubing to length so as to form separate short sleeves each containing an appropriate indicia or marking.

The chopping of the length of flattened tubing into short lengths may not be complete so that the lengths are separated by necked regions which can be readily snapped or cut so that the complete set of sleeves for a cable harness can be all joined together along a length of flattened tubing which can then be rolled or otherwise stored and by printing them in an appropriate order, so the different sleeves will be available next in turn along the length as the sleeve sections are removed one by one.

By appropriate choice of plastics materials so the flattened sleeve sections will be capable of being reshaped to a generally circular cross-section to allow them to be slipped onto the end of a cable by simply being squeezed between the finger and thumb.

Alternatively a special tool may be provided for opening the section up.

According to another aspect of the present invention apparatus performing the above method comprises a first fluid chamber containing a fluid at a first elevated temperature, a reduced section communicating passage between the first chamber and a second chamber containing the same or a similar fluid at a lower termperature, means for causing a circular section tube of plastics material to enter the first chamber and pass therethrough so as to be heated, to pass through the reduced section communicating passage and thereafter through the second chamber, the apparatus being designed or adpated to create an elevated hydrostatic pressure in the fluid at least in the region of the communicating passage and preferably for some distance in each zone on either side of the passage, a printing or other marking device situated beyond the second chamber through which the flattened tubing is passed and which is adapted to print or otherwise mark the tube on one or other or both of the two flat surfaces thereof, and means for taking up the printed tube and storing same in a reel orthe like.

The apparatus may further comprise a perforating or severing or part severing tool for cutting or partially cutting the long length of flattened tube before or after printing into sections each containing a unique marking or name specific to a cable for a cable harness.

Preferably the apparatus further comprises drying means between the output of the second chamber and the printer or other marking device where it is important that tube is not wet as it enters the printer.

The liquid in the first and second chambers is preferably the same and may be water but more typically will bea liquid having a higher density such as a halogenated hydro carbon or a low melting point metal such as mercury. By using a substance such as mercury the head required to produce for example 2 bars of pressure will be reduced to approximately 1.5 metres as compared with the 20 metres head required if water is used.

The invention further comprises a length of flattened plastics tubing having print or marking therealong and partial severence or perforation between adjacent sections containing different markings, each of the separable sections comprising a flattened sleeve which can be slipped onto a cable of a cable harness or the like to denote the cable concerned by a name or code or other indication.

The invention also lies in a cable harness marking sleeve when formed by the above method or formed using the above apparatus.

The invention will now be described by way of example with reference to the accompanying drawings in which: The drawing(s) originally filed was/were informal and the print here reproduced is taken from a later filed formal copy.

Fig. lisa diagrammatic representation of a 'U' tube based apparatus for producing flattened tube for feeding to a printer, and Fig. 2 is an alternative apparatus not requiring a 'tJ' tube and therefore excessive head room in order to generate hydrostatic pressure which may be used in place of the 'U' tube apparatus of Fig. 1 for feeding the printer.

Fig. 1 shows a simple form of apparatus comprising a 'U'tube having vertical legs 110 and 12 and a curved bridging base 14. Within the latter is located a seal 16 having an aperture through which a flattened tube can pass.

Fig. 1a is a cross-section on the line AA of Fig. 1 and illustrates the cross-sectional shape of the seal 16 and the aperture 18 therein through which the flattened tube designated by reference numeral 20, can pass.

The'U' tube 10,120,14 is filled with a liquid and in the leg 10 is located a heater 22 and in the leg 12 a cooling element 24. The size and position of these heating and cooling elements 22 and 24 is shown rather more diagrammatically than actually since it will be appreciated that the cooling element 24 will probably need to be closer to the seal 16 than as shown.

A round section or similar tube 26 passes around an entrance roller 28 which has a deep annular valley shaped to conform to the round section of the tube 26. The tube passes into the upper end of the leg 10 of the 'U' tube.

As the tube passes down the leg 10 it is heated to a temperature typically of the order of 80"C and as the pressure increases due to the hydrostatic head, the tube walls collapse and the round section becomes generally flat as shown at 20 in Fig. la.

After passing through the seal 16 (which is primarily only a thermal seal and is intended to be a thermal seal). The flattened tube begins to traverse up through the leg 12 where it is immediately cooled due to the lower temperature maintained on that side of the seal 16.

An exit roller 30 is located at the upper end of the tube leg 12 and flattened section of the tube 20 passes around this exit roller 30 and traverses to a take-up drum or the like.

Beyond the exit roller 30 is located a driver 31 which removes any surplus moisture from the surface of the flattened tube 20.

Beyond the dryer the tube passes between nip rollers 33 and 35 of the input of a printing machine containing a platen 37 and printing head 39 which is adapted to imprint onto the flattened surface of the flattened tube 20 indicia numbers or other markings at intervals along the length of the flattened tubing.

The latter after being printed is returned through a second nip 41 and 43 to a perforating station 45 at which perforations are formed at regular intervals along the length of the tube 20 commensurate with the spacing between the printed indicia or other markings so as to form a long length of flat plastics material having printed indicia or other markings along the length thereof separate by perforations.

The separate sections so formed containing unique markings can then be removed by tearing or simply pulling from the remainder of the length.

As opposed to perforations, partial severance leaving a necked region between adjoining sections or complete severance may be employed.

Fig. 2 illustrates an alternative apparatus which can be used in place of the 'U' tube configuration of Fig 1 and serves to feed flattened tube to the input of a similar dryer and printer which although not shown in Fig. 2 can be taken to be similar to that shown in Fig. 1.

Referring to Fig. 2 the apparatus shown therein consists of two pumped fluid circulation loops generally designated 32 and 34.

Each of the circuits is essentially similar and comprises a pump 36 or 38, a heat exchanger 40 acting so as to heat the fluid passing therethrough and the heat exchanger 32 acting so as to cool the fluid passing therethrough in the other circuit, a venturi 44 in circuit 32 and a similar venturi 46 in the other circuit 34, a thermal seal 48 between the two circuits and a return path 50 or 52 leading to storage tanks 54 and 56 which maintain the supply of fluid along the return paths 58 and 60 to the two pumps 36 and 38.

The apparatus includes a vertical entrance tube 62 and a vertical exit tube 64 which communicates with the upstream side of each of the venturis 44 and 46 respectively and provide inlets and outlets for a tube which enters in an unflattened condition, typically having a round section at 66 and after passing along the horizontal legs 68 and 70 passing through the seal 48, can pass as a flattened tube out through the vertical tube 64 as at 72. Entrance and exit rollers 74 and 76 are provided where appropriate.

The pumps 36 and 38 not only provide for a circulation of the fluid so as to maintain the temperatures in the operating regions of the apparatus at the required levels but also provide the requisite pressure to collapse the tube. Thus the pressure of the liquid is raised to a pressure Pf in the region 78 and 80 of each of the circuits 32 and 34 respectively and this pressure is sufficient to collapse the wall of the tube. Typically it is of the order of 2 bar.

The pressure is then reduced across the venturis 44 and 46 respectively to a reduced pressure Pt at the venturi throat and the geometry of the venturi is arranged to make the throat pressure Pt slightly higher than atmospheric pressure so that a small vertical stand pipe 62 or 64 communicating with the throat of the venturi will have a modest level of fluid H maintained in it whilst the pump is running. This enables the plastics tubing 66 to be introduced into the circulating fluid via the stand pipe on the hot side than to exit in the same manner on the opposite side of the apparatus.

The defuser of the venturi enables the flattening pressure Pf to be substantially recovered at its exit.

The hot and cold circulation loops interconnect via the seal 48 through which the tubing passes.

Each section of the tube as it passes through the apparatus thus experiences heat pressure chill and releaser pressure as it passes through the apparatus and is thereby flattened.

Orifice plates 82 and 84 are provided to control the pressure.

A balance pipe 86 is provided to ensure that any net fluid transfer through the seal may overflow back into the system from which it originated. As previously mentioned the output of flattened tube from the exit roller 76 is supplied to a dryer such as 31 shown in Fig. 1 and printer and perforator all as shown in Fig. 1.

CLAIMS (Filed on 29/9/82) 1. A method of forming a printed sleeve for fitting over the end of an insulated wire forming part of a cable harness comprises the steps of:a) continuously moving a long or endless length of round section tubing into a first zone in which the tube wall is heated to a first elevated temperature; b) increasing the external pressure acting on the wall of the tube to cause the latter to collapse and form a flat section tube; c) causing the flattened section of tube to move into a second cooler zone where the reduced temperature causes the plastics material to set in the flattened condition; d) either in said second zone or after the material has passed through the second zone, reducing the pressure acting on the external surfaces of the tube to normal atmospheric pressure; e) causing the tube to pass to a printer at which indicia such as letters, numerals etc, are imprinted or otherwise marked onto the flattened surface.

2. A method as claimed in claim 1 comprising the further step of cutting the length of flattened tubing to length so as to form separate short sleeves before or after printing.

3. The method as claimed in claim 2 wherein the chopping of the flattened tubing into short lengths is incomplete so that the separate short lengths are separated by necked regions which can be readily snapped or cut so that a plurality of sleeves for a cable harness are all joined together.

4. The method as claimed in claim 3 wherein the printing is performed in an order such that the different sleeves along the length of the partially severed length are in the order in which they will be required.

5. A method as claimed in any of claims 1 to 4 in which the flattened sleeve sections are reshaped to a generally circular cross-section after printing to allow them to be slipped onto the end of a cable.

6. A method as claimed in claim 5 in which the reshaping is achieved manually by squeezing the strip between the finger and thumb.

7. Apparatus for performing the method of claim 1 comprising a first fluid chamber containing a fluid at a first elevated temperature, a reduced section communicating passage between the first chamber and a second chamber containing the same or a similar fluid at a lower temperature, means for causing a circular section tube of plastics material to enter the first chamber and pass therethrough, so as to be heated, to pass through the reduced section communicating passage and thereafter through the second chamber to be cooled. the apparatus creating an elevated hydrostatic pressure in the fluid at least in the region of the communicating passage, and a printing or other marking device situated beyond the second chamber and adapted to receive the flattened tubing therefrom and which is adapted to print or otherwise mark the tube on one or other or both of the two flat surfaces thereof.

8. Apparatus as claimed in claim 7 further com prising means for taking up the printed tube and storing same in a reel or the like.

9. Apparatus as claimed in claim 7 or 8 further comprising a perforating severing or part-severing tool for cutting or partially cutting the long length of flattened tube into small lengths before or after printing.

10. Apparatus as claimed in claim 7 or 8 or 9 further comprising drying means between the output of the second chamber and the printer or other marking device to dry the tube before it enters the printer or other device.

11. Apparatus as claimed in any of claims 7 to 10 in which the liquid in the first and second chambers is the same.

12. Apparatus as claimed in claim 11 wherein the liquid is water or a liquid having a higher density such as a halogenated hydrocarbon or a low melting point metal such as mercury.

13. A length of flattened plastics tubing having printing or marking therealong and partial severance or perforation between adjacent sections containing different markings, each of the separable sections comprising a flattened sleeve which can be slipped onto a cable of a cable harness or the like to denote the cable concerned by the marking thereon.

14. A cable harness marking sleeve when formed by the method as claimed in any of claims 1 to 6 or formed using the above apparatus.

15. A cable harness marking sleeve when formed using the apparatus as claimed in any of claims 7 to 12.

16. Apparatus as claimed in claim 7 constructed arranged and adapted to operate substantially as herein described with reference to the accompanying drawings.

17. A method substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. A balance pipe 86 is provided to ensure that any net fluid transfer through the seal may overflow back into the system from which it originated. As previously mentioned the output of flattened tube from the exit roller 76 is supplied to a dryer such as 31 shown in Fig. 1 and printer and perforator all as shown in Fig. 1. CLAIMS (Filed on 29/9/82)

1. A method of forming a printed sleeve for fitting over the end of an insulated wire forming part of a cable harness comprises the steps of:a) continuously moving a long or endless length of round section tubing into a first zone in which the tube wall is heated to a first elevated temperature; b) increasing the external pressure acting on the wall of the tube to cause the latter to collapse and form a flat section tube; c) causing the flattened section of tube to move into a second cooler zone where the reduced temperature causes the plastics material to set in the flattened condition; d) either in said second zone or after the material has passed through the second zone, reducing the pressure acting on the external surfaces of the tube to normal atmospheric pressure; e) causing the tube to pass to a printer at which indicia such as letters, numerals etc, are imprinted or otherwise marked onto the flattened surface.