AU2019100444A4 - Cooling assembly for extruded plastic pipe - Google Patents

Abstract

P5755AU00 11 A cooling assembly (110) for cooling a rapidly extruded plastic pipe (118). The cooling assembly (110) has an upper, first trough (112, 114, 116) or bath that is used for cooling the extruded pipe (118) entering the cooling assembly (110). The upper trough may contain water as a cooling liquid. The cooling pipe (122) is guided by a first sheave (126) from the upper trough to a lower trough (128, 130, 132) and then back up to the upper trough by a second sheave (136). Continuous, parallel loops of the cooling pipe (122) may be done about the upper trough, the first sheave, the lower trough and the second sheave until the cooled pipe (212) exits the cooling assembly (110). Figure number: 1 1 -w VEt isD ½D

Description

COOLING ASSEMBLY FOR EXTRUDED PLASTIC PIPE.

BACKGROUND OF THE INVENTION

1. Field of the Invention [0001] The present invention relates to cooling tanks for extruded plastic pipe. The invention may also relate to the cooling of higher speed extruding of plastic pipes of smaller diameter.

2. Description of the Art [0002] Plastic pipe is often produced by extruding molten plastic through a suitable die and then cooling the extruded pipe in a cooling tank or a bath. Typically the pipe is extruded continuously into one or a series of cooling tanks. The combined length of the cooling tanks being chosen to achieve a cooled plastic pipe that is rigid and ready for use. Water is often used for a cooling liquid in the cooling tanks.

[0003] In one example application area of producing polyethylene (PE) irrigation pipe of approximate 25 mm diameter: a modem extruder may produce such pipe at speeds of up to 20 meters per minute, or more. A series of cooling tanks of up to 40 to 50 metres, or more, in combined length may be needed in order to achieve the necessary cooling residence time for such rapidly extruded pipe.

[0004] There are various known arrangements and constructions for cooling tanks. Long lengths of cooling tanks or baths to achieve the necessary cooling residence time are a common feature. Such long, series arrangements of cooling tanks require a large factory floor footprint in addition to the pipe extruder.

[0005] None of these prior art apparatuses provides an entirely satisfactory solution to the provision of extruded pipe cooling, nor to the ease of locating the cooling tanks in factory spaces.

[0006] Any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by

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P5755AU00 2 those skilled in the art to which the invention relates, at the priority date of this application.

SUMMARY OF THE INVENTION [0007] The present invention aims to provide a cooling assembly which overcomes or ameliorates the disadvantages of the prior art, or at least provides a useful choice.

[0008] In one form, the invention provides a cooling assembly for extruded pipe comprising: an upper trough and a lower trough, each trough containing a cooling liquid; and a first sheave and a second sheave between respective ends of the upper trough and the lower trough; wherein the pipe traverses the upper trough and then the pipe is guided to the lower trough by the first sheave; and wherein the cooling pipe traverses the lower trough and then the second sheave guides the pipe from the lower trough to the upper trough; whereby continuous, parallel loops of the pipe about the upper trough, first sheave, lower trough and second sheave are run in the cooling tank assembly until the cooled pipe exits the cooling assembly.

[0009] In another form the invention provides a cooling assembly for extruded plastic pipe comprising: a first trough and a second trough, each trough containing a cooling liquid; and a first pipe guide and a second pipe guide between respective ends of the first and second troughs; wherein the pipe traverses the first trough and then is continuously looped about first pipe guide, the second trough and the second pipe guide back to the first trough to form at least two parallel pipe loops in the cooling assembly before the cooled pipe exits the cooling assembly.

[0010] The first and second pipe guides are respective wheels, circumferentially grooved for each pipe loop to form respective sheaves. Alternatively, each wheel of a sheave may have small idler wheels mounted about the rim of each wheel.

[0011] The first trough is above the second trough. Alternatively, the first trough and second trough are side by side. In another alternative the troughs are replaced by parallel, vertical, spray cabinets with guiding sheaves mounted at each end.

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P5755AU00 3 [0012] The cooling assembly including a tractor head applied to the cooled pipe.

[0013] The tractor head is controlled by a tension of the looped pipe.

[0014] The first and second troughs comprise of a number of trough units that are removable.

[0015] In an alternate form the invention provides a cooling assembly as substantially described herein with reference to the accompanying figures.

[0016] Further forms of the invention are as set out in the appended claims and as apparent from the description.

DISCLOSURE OF THE INVENTION

BRIEF DESCRIPTION OF THE DRAWINGS [0017] The description is made with reference to the accompanying drawings, of which:

[0018] FIGURE 1 is a schematic of a side elevational view of a cooling assembly for cooling an extruded plastic pipe.

[0019] FIGURE 2 is a schematic of a plan view of the cooling assembly of FIGURE 1, showing the upper trough.

[0020] FIGURE 3 is a schematic of a transverse cross-sectional view along the lines 3-3 in FIGURES 1 and 2.

[0021] FIGURE 4 is a schematic of a transverse cross-sectional view along the lines 4-4 in FIGURES 1 and 2.

[0022] FIGURE 5 is a schematic of a plan view of a tractor head of a traction drive of the cooling assembly of FIGURE 1.

[0023] FIGURE 6 is a schematic of an end elevational view of the tractor head of FIGURE 5, looking towards the second sheave cabinet.

[0024] In the figures the reference numerals are prefixed by the figure number. For example FIG 1 is the “100” series, FIG 2 is the “200” series and so on.

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P5755AU00 4

DETAILED DESCRIPTION.

[0025] FIGURE 1 is a schematic of a side elevational view of a cooling assembly 110 for cooling extruded plastic pipe 118. FIGURE 1 is shown in longitudinal sectional view. The cooling assembly 110 has an upper, first trough 112, 114, 116 or bath that is used for cooling the extruded pipe 118 entering the cooling assembly 110. The upper trough or cooling bath may contain water as a cooling liquid.

[0026] The upper trough may be made up of a number of removable / detachable trough units depending on the length desired for the upper trough. In the FIGURE 1 example shown, the extruded pipe 118 enters an upper entry trough unit 112 and passes beneath one of multiple rollers 120 that may be used to aid in submerging the cooling pipe 122 in the cooling liquid. The cooling pipe 122 traverses the length of the entry trough unit 112 and then passes through an aperture in the joint wall between the entry trough unit 112 and the upper centre trough unit 114. As before the cooling pipe 122 is submerged and traverses the length of centre trough unit 114 to then enter the last, exit trough unit 116. The cooling pipe exits the last upper trough 116 into a first sheave cabinet 124 via a water sealed aperture. The apertures between the trough units and at their ends are described further below with respect to FIGURES 3 and 4.

[0027] The first sheave cabinet 124 contains a first sheave 126 suitable for guiding the flexible, cooling pipe 122 down to a parallel, lower, second trough 128, 130, 132 for further cooling. That is, the first sheave 126 functions as a first pipe guide 126 from the upper exit trough 116 to the lower entry trough 128. As for the upper trough 112, 114, 116 the lower trough 128, 130, 132 may made up of a number of trough units. As shown in the FIGURE 1 example, the lower trough has a lower entry trough unit 128, a lower centre trough unit 130 and a lower exit trough 132. The cooling pipe 122 passes through the lower three trough units 128, 130, 132 submerged in the cooling liquid with the aid of the rollers 120. From the lower trough 128, 130, 132 the cooling pipe 122 passes into the second sheave cabinet 134 to be guided by a second sheave 136 up and back into the upper trough 112, 114, 116 for further cooling. As for the first sheave, the second sheave 136 also functions as a second pipe guide 136.

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P5755AU00 5 [0028] FIGURE 2 is a schematic of a plan view of the cooling assembly 110 of FIGURE 1, showing the upper trough 112, 116, 118. The example sheaves 126, 136 shown in FIGURE 2 are as coaxial wheels 211 with circumferential grooves for the cooling pipe 120. The circumferential grooves may be in the form of plastic pipe guides attached to the circumference of each wheel. Each sheave may be freewheeling as the movement of the cooling pipe 122 through the cooling assembly may be controlled by a traction drive 210 acting on the cooled pipe 212 exiting the cooling assembly 110. The traction drive 210 is described below with respect to FIGURES 5 and 6. Optionally each of the wheels 211 in a sheave 126, 136 may also rotate independently.

[0029] It will be readily appreciated that the sheaves 126, 136 may also be in the form of a drum with suitable grooves. In another alternative each pipe guiding sheave may be replaced by an arrangement of parallel, static pipe guides between the upper and lower troughs. The pipe guides may have low friction inserts to aid in the movement of the wet pipe 122 over the pipe guides.

[0030] In yet another alternative the sheaves 126, 136 with the coaxial wheels 211 and circumferential grooves may instead be replaced with wheels where about the circumferential rim, small idler wheels, discs or rollers with their own circumferential groove are mounted with their axles through opposing rims of a wheel making up the alternate sheave. The use of such a circular array of small idler wheels reduces the contact area with the cooling pipe.

[0031] In the FIGURES 1 and 2 example of the cooling assembly 110, the three wheels 211 making up each of the first and second sheaves 126, 136 enables three complete, substantially parallel, continuous loops of the cooling pipe 122 to be run around the upper trough 112, 114, 116, first sheave 126, the lower trough 128, 130, 132 and the second sheave 136. After the cooling pipe 122 has looped continuously through cooling assembly a number of times, the cooled pipe 212 exits via the traction drive 210. The cooled pipe 212 may then be coiled by a suitable high speed coiler.

[0032] The cooling assembly’s 110 surprisingly efficient and compact reconfiguration of pipe cooling is highly advantageous. The example cooling assembly 110 shown in FIGURES 1 and 2 may be approximately 10 metres long for adequately

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P5755AU00 6 cooling 25 mm diameter PE pipe from a modem extruder operating at a maximum extrusion or production rate. A prior art series of cooling tanks or baths providing the same cooling length may be approximately 50 metres in length. The considerably reduced footprint, approximately a factor of seven, provides advantages to savings in factory floor-space which may be utilised for high speed pipe coilers and adding further pipe manufacturing lines.

[0033] It will be readily appreciated that more or less pipe loops may be used in the cooling assembly 110 by using respectively more or less wheels 211 for each of the sheaves 126, 136. Alternatively for less pipe loops the extruded pipe 118 may enter into the upper trough 112 at another water sealing aperture above the second sheave 136. For example above a wheel 211 in the sheave 136 depending on how many loops in the cooling assembly are required. The water sealing apertures are described further with respect to FIGURE 4.

[0034] In FIGURE 2 a number of rollers 120 are shown spaced apart in the upper trough units 112, 114, 116. Each roller 120 may also have circumferential grooves to aid in maintaining the separation between the submerged pipe loops. Furthermore each roller 120 may be made up of four, as shown by way of example in FIGURE 2, grooved cylinders 214 that may rotate independently as well as move along the common shaft mounting the grooved cylinders 214 making up the roller. Such a floating arrangement of the grooved cylinders along the common shaft may aid in the free running and spacing of the multiple, parallel loops of cooling pipe. The rollers 120 in the upper and lower troughs may also be varied in their depth within each trough so as to accommodate different pipe diameters.

[0035] In FIGURES 1 and 2 overflow drains 138 are shown in each trough unit. The overflow drains 138 are configured so that the cooling liquid level in each trough unit is maintained above the shaft of the rollers 120 and the cooling pipe 122.

[0036] FIGURE 3 is a schematic of a transverse cross-sectional view along the lines 3-3 in FIGURES 1 and 2. The cross-sectional view shown in FIGURE 3 is the common walls between the upper entry and centre trough units 112, 114 and the lower centre and exit trough units 130, 132. Apertures 310, 312 in the common walls of the adjacent trough units allow the approximately parallel lengths of looped cooling pipe 122 to pass from one trough unit to the next. The four apertures 310 of the upper

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P5755AU00 7 trough and the three apertures 312 of the lower troughs, are shown in FIGURE 3. The apertures 310, 312 and their panels may be of a suitable material that does not bind with or damage the cooling pipe 122. The gasket between each of the trough units or tanks may be of suitable rubber gasket, for example Linatex®.

[0037] FIGURE 4 is a schematic of a transverse cross-sectional view along the lines 4-4 in FIGURES 1 and 2. The cross-sectional view shown in FIGURE 4 is the common wall between the upper trough 112, the lower trough 132 and the second sheave cabinet 134. The extruded pipe 118 enters the cooling assembly 110 via second sheave cabinet 134. Four, upper, water sealing apertures 410, 412 for entering the upper trough 114 are shown. The extruded pipe 118 enters the upper entry trough 114 via a side aperture 410. The other three water sealing apertures 412 are for the cooling pipe 122 returning to the upper trough 112, 114, 116 from the lower trough 128, 130, 132. The extruded pipe 118 may also first enter the upper trough by one of the other three water sealing apertures 412 if less pipe loops are desired in the cooling assembly 110, as described above with respect to FIGURE 2.

[0038] Three, lower water sealing apertures 414 are also shown in FIGURE 4. The lower water sealing apertures 414 are for cooling pipe 122 loops exiting the lower trough.

[0039] The common wall between the first sheave cabinet and the upper exit trough 116 and the lower entry trough 128 also has similar water sealing apertures to those described and shown in FIGURE 4. Those water sealing apertures are also used to allow the cooling pipe 122 loops to exit the upper trough and enter lower trough without appreciable loss of cooling liquid.

[0040] FIGURE 5 is a schematic of a plan view of a tractor head 510 of the traction drive 210. A mounting plate 512 is used to attach the tractor head 510 to the first sheave cabinet 124 at the exit of the cooled pipe 212 from the cooling assembly 110. The tractor head 510 may have a traction drive roller 514 and a traction idler roller 516 to clamp and control the movement of the cooled pipe 212. The drive roller 514 and the idler roller 516 may each be suitably mounted on pivoting arms 518, the pivoting arms being suitably coupled to the mounting plate 512. A pneumatic actuator 520 joining the two pivoting arms 518 may be used to suitably clamp and release the exiting cooled pipe 212 as needed.

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P5755AU00 8 [0041] FIGURE 6 is a schematic of an end elevational view of the tractor head

510 of FIGURE 5, looking towards the second sheave cabinet 124. FIGURE 6 is also a sectional view through the common plane to the traction drive and idler roller 514, 516 axes or shafts. A compressed air turbine motor 610 may be used to drive the drive roller 516. It will be readily appreciated that a person skilled in the art may design and select appropriate controls and regulators for the tractor head 510 as part of the traction drive 210. It will also be readily appreciated that compressed air or pneumatic controls, actuators and turbine motors are preferred due to the wet environment about the cooling assembly 110.

[0042] Advantageously an automatic feedback control loop may be done between the traction drive 210 and a sensed or derived tension in at least one of the cooling pipe 122 loops within cooling assembly 110. That is, the tractor head is controlled by a tension of the looped cooling pipe. Such an integrated tension control may be used to prevent undue stretching and pipe wall thinning of the cooling pipe 122 versus maintaining sufficiently taut pipe loops for low drag and distortion free pipe.

[0043] It will be readily appreciated that the parallel arrangement of the upper and lower troughs may be varied in orientation. For example rather than a vertical orientation of the upper and lower troughs, they may be in a side by side arrangement. The sheaves would then be horizontal with a vertical axis of rotation. In another alternative the horizontal troughs may be replaced by respective vertical cabinets with spray nozzles rather than a liquid cooling bath. Between the respective ends of the vertical cabinets, first and second sheaves 126, 136 may be located to guide the cooling pipe 122 in vertical, parallel loops in the parallel, vertical, spray cabinets.

[0044] It will be readily appreciated that the cooling assembly 110 components may be designed and selected to enable other extruded pipe diameters and materials to be cooled and still be within the scope of the invention.

[0045] In this specification, terms denoting direction, such as vertical, up, down, left, right etc. or rotation, should be taken to refer to the directions or rotations relative to the corresponding drawing rather than to absolute directions or rotations unless the context require otherwise.

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P5755AU00 9 [0046] Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiments, it is recognized that departures can be made within the scope of the invention, which are not to be limited to the details described herein but are to be accorded the full scope of the appended claims so as to embrace any and all equivalent assemblies, devices, apparatus, articles, compositions, methods, processes and techniques.

[0047] In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of’. A corresponding meaning is to be attributed to the corresponding words “comprise, comprised and comprises” where they appear.

Claims (5)

1. A cooling assembly for extruded pipe comprising:

an upper trough and a lower trough, each trough containing a cooling liquid; and a first sheave and a second sheave between respective ends of the upper trough and the lower trough;

wherein the pipe traverses the upper trough and then the pipe is guided to the lower trough by the first sheave; and wherein the cooling pipe traverses the lower trough and then the second sheave guides the pipe from the lower trough to the upper trough;

whereby continuous, parallel loops of the pipe about the upper trough, first sheave, lower trough and second sheave are run in the cooling tank assembly until the cooled pipe exits the cooling assembly.

2. A cooling assembly for extruded plastic pipe comprising:

a first trough and a second trough, each trough containing a cooling liquid; and a first pipe guide and a second pipe guide between respective ends of the first and second troughs;

wherein the pipe traverses the first trough and then is continuously looped about first pipe guide, the second trough and the second pipe guide back to the first trough to form at least two parallel pipe loops in the cooling assembly before the cooled pipe exits the cooling assembly.

3. A cooling assembly according to claim 2, wherein the first and second pipe guides are respective wheels, circumferentially grooved for each pipe loop.

4. A cooling assembly according to claim 2 or 3, wherein the first trough is above the second trough.

5. A cooling assembly according to any one of claims 2 or 3, wherein the first trough and second trough are side by side.