CH706446A1 - Machine and manufacturing process by extrusion of irrigation pipes. - Google Patents

Abstract

An irrigation pipe making machine comprising: an extrusion station (8); a calibrator (2); a dripper supply system (3) for bringing drippers (4) into contact with the inner surface of pipes (1) being hardened at the exit of the extrusion station; one or more elements (2, 3, 5, 6) in contact with said pipe (1) and / or with said emitters (4) in the calibrator (2) or downstream of the calibrator. A vibrator (6) applies vibration to one or more of said elements to reduce friction against the pipe and the risk of tearing.

Description

Technical area

The present invention relates to a machine and a method of manufacturing by extrusion of irrigation pipes.

State of the art

Known in the state of the art irrigation pipes made of a polymer material and including drippers distributed at a more or less regular distance inside the pipe. The irrigation water passes through the drippers which limit the flow before leaving the pipe through openings in the side walls. Drippers are usually caught in the pipe wall during extrusion.

An example of a machine for manufacturing such pipes is described in EP0 344 605. In this document, the drippers are fixed and fused to the pipe inside the calibrator that determines the diameter of the pipe. At high speed, or when the irrigation pipes have very thin walls, the friction force caused by the support of the dripper against the internal surface of the pipe being calibrated sometimes causes a tear of the pipe during its manufacture.

Solutions have been proposed in the state of the art to reduce the risk of tearing the pipe when attaching drippers. No. 6,461,468 discloses a manufacturing machine in which the drippers are pressed inside a calibrator against the inner surface of the pipe being cured at the outlet of the extrusion station. The outer surface of the pipe bears against the calibrator. A series of rollers inside the pipe allow the drippers to advance inside the pipe while being pressed against the pipe. These rollers reduce friction. However, the pipe is simultaneously subjected to a longitudinal elongation force against the calibrator, and a radial force exerted by the pressure of the dripper exerted against the same portion of pipe.

In another embodiment, US 6,461,468 suggests using a backing roll against the outer surface of the pipe engaged through an opening in the sizer. This wheel reduces the friction of the external bearing surface against which the pipe is pressed by the drippers.

[0006] EP 0 970 602 discloses another machine in which the drippers are supported by a ramp against the inner surface of the pipe being hardened, while an endless belt forms a bearing surface on the outside of the pipe. . Attaching the drippers downstream of the calibrator dissociates the elongation of the pipe during its formation in the calibrator and the pressure force of the dripper against the pipe. The use of a belt also makes it possible to reduce the friction of the external surface of the pipe against the bearing surface. However, the sliding of the drippers with respect to the internal surface of the pipe still causes risks of tearing.

A similar solution is described in EP 1 006 778.

[0008] EP 1 104 983 discloses a machine in which a series of rollers allows the drippers to advance inside the pipe at the outlet of the calibrator, while a wheel forms a bearing surface outside the pipe. The drippers and the pipe are thus pressed against each other between two moving surfaces, which reduces the friction and the risk of tearing.

Brief summary of the invention

An object of the present invention is to further reduce the friction forces and the risk of tearing during the extrusion manufacture of an irrigation pipe.

According to the invention, these objects are achieved in particular by means of an irrigation pipe manufacturing machine comprising; an extrusion station; a calibrator; a feeder feed system for bringing emitters into contact with the inner surface of the pipes being hardened at the outlet of the extrusion station; one or more elements in contact with said pipe and / or with said drippers in the calibrator or downstream of the calibrator; and a vibrator for applying a vibration to one or more of said elements.

The application of vibration to the elements in contact with the pipe during curing in or downstream of the calibrator reduces the frictional forces between the still fragile pipe and these elements.

In particular, experiments have shown that the use of high frequency vibrations, for example vibrations with a frequency greater than 500 Hz or preferably greater than 20 KHz can significantly reduce the risk of tearing of the pipe in this portion of the extrusion machine The vibration frequency can advantageously be adjusted, for example to adapt it to the longitudinal extrusion speed, the thickness of the pipe, etc.

The frequency can also be adjusted automatically by scanning a frequency range, for example a range between 20 and 50 KHZ, until finding a resonance.

Experiments have also shown that, unexpectedly, the exposure of the tube and ultrasound emitters had the effect of promoting the welding of these two components, and to obtain an ultrasound welding whose effect is superimposed thermal welding alone.

It is also possible to simultaneously apply vibrations with several different frequencies. For example, it is possible to simultaneously apply vibrations with several different discrete frequencies, or vibrations whose frequency is distributed in a spectral band.

The vibrations can be applied in the longitudinal direction of the pipe. The vibrations can also be applied in at least one direction substantially perpendicular to the extrusion direction, for example in a direction substantially radial with respect to the pipe. The vibrations can also be applied simultaneously in several different directions.

The vibrations may for example be applied against a dripper supply ramp, that is to say a ramp that brings the drippers in contact with the inner face of the pipe. The vibration is thus transmitted to the drippers to promote their penetration without tearing in the wall of the pipe being formed.

The vibrations may for example be applied against a support piece outside said pipe and against which the outer surface of the pipe is supported when drippers are pressed against the inner surface of the pipe. The friction of the pipe against this support piece is thus reduced.

Vibration can also be applied against a calibrator, a portion of which serves as a support against which the outer surface of the pipe is supported when drippers are pressed against the inner surface of the pipe.

The vibrations can be applied against several distinct elements, by means of one or more separate vibrators. The frequency of vibration applied to different elements may be different, or it may be the same. The direction of vibration applied to different elements may be different, or it may be the same.

The vibrations can be applied to a fixed element relative to the machine. The vibrations can also be applied to a movable element relative to the machine, for example a roller, a roller, an endless belt, etc. The vibrations can be applied to a motorized element or driven by the pipe itself.

The vibrations can be made by means of a vibrator, for example a vibrator based on a piezoelectric element. The vibrations may be applied to one or more elements downstream of the calibrator, in a portion in which the extruded pipe has not yet hardened.

In order to further reduce friction, the surface of a said element may be provided with a coating, for example a teflon coating, and / or a surface treatment.

At least one of the elements subjected to vibration may be movable radially relative to the pipe, to adjust the pressure against the pipe. At least one of the vibrating members may be radially displaceable relative to the pipe by means of a pressure regulating member for imposing a set distance. At least one of the vibrating members may be radially displaceable relative to the pipe by means of a spring or other resilient member exerting pressure on the pipe.

Brief description of the figures

Examples of implementation of the invention are indicated in the description illustrated by the accompanying figures in which; <tb> Fig. 1 <sep> illustrates a partial sectional life of a machine according to a first embodiment. <tb> Fig. 2 <sep> illustrates a partial sectional life of a machine according to a second embodiment. <tb> Fig. 3 <sep> illustrates a partial sectional life of a machine according to a third embodiment. <tb> Fig. 4 <sep> illustrates a partial sectional life of a machine according to a fourth embodiment.

Example (s) of embodiment of the invention

Fig. 3 1 is a partial sectional view of a machine for manufacturing by extrusion of irrigation pipes according to one embodiment of the invention. The general principle of such machines is known, in particular from the patent applications EP 0 344 605, US 6 461 468, EP 0 970 602, EP 1 006 778 or EP 1 104 983 mentioned above, the content of which is incorporated herein. by reference; those skilled in the art will usefully refer to these documents for the implementation of the solution, and only aspects of the machine useful for understanding the present invention are described here in more detail.

The element 1 in FIG. 1a cross-sectional view of half of an irrigation pipe being manufactured; the pipe is produced by extrusion from the extrusion station 8 shown schematically. The final diameter of the pipe is determined by one or more calibrators 2 crossed by the extruded material still soft before cooling. The element 3 represents a dripper supply system for bringing drippers 4 one after the other at a regular distance against the inner surface of the pipe 1, in order to merge against the inner surface during hardening. In the example illustrated, the system or element 3 is constituted by a ramp, for example a metal ramp, on which drippers from a source of drippers move for example under the effect of a pulsed air jet , vibrations or thanks to the actuation of a mechanical pusher for example. Feeder delivery systems comprising a conveyor with motorized or non-motorized rollers, motorized rollers or not, or other elements making it possible to facilitate the transport of the drippers to the point of contact C with the pipe can also be used. used in all variants of the invention.

At point C, the drippers are pressed by the ramp 3 against the inner surface of the pipe 1 not yet hardened, to merge in this surface. Outside the pipe, the element 6 constitutes a bearing surface to prevent the pressure of the dripper from deforming the pipe durably, the radial position of this element can be adjusted, for example by means of a set screw , depending on the thickness of the pipe to be produced. The position of this element can also be adjusted dynamically, for example by means of a spring or another elastically compressible element, in order to exert a permanent pressure against the pipe 1 while adapting to small differences in 'thickness.

According to one embodiment of the invention, the support element 6 outside the pipe is constituted by a vibrator, or is connected to such a vibrator arranged to put it in vibration. The support element may for example be constituted by, or linked to, a sonotrode subjected to an ultrasonic energy, for example an energy in a frequency greater than 20 KHz, or in a frequency band greater than 20 KHz.

The frequency can also be adjusted automatically by scanning a frequency range, for example a range between 20 and 50 KHZ, until finding a resonance. This adjustment can be made at design, when mounting a particular machine, or at startup.

The vibrations applied to the element 6 are preferably oriented in the radial direction of the pipe 1, they have the effect of facilitating the sliding of the pipe against the vibrating surface of the element, in that the contact time between the element 6 and the pipe 1 is reduced. Vibrations applied in another direction, for example longitudinal, may also be used. It is also possible to combine vibrations in several different directions, or to apply vibrations in a direction that changes over time.

FIG. 2 illustrates another embodiment of the invention in which the drippers 4 are supported between a ramp 3 and an external bearing surface constituted by a prolonged portion of the calibrator 2. This calibrator is connected to a vibrator, for example a sonotrode, which applies ultrasonic vibrations to facilitate the sliding of the pipe on the inner face of the calibrator, in the contact zone with the drippers C. In this example, the vibrations are longitudinal to create compression waves with a surface inner corrugated calibrator, thus minimizing the contact area. Another sonotrode 7 can be used to apply vibrations in another direction, for example radial.

It is also possible to apply vibrations to the ramp 3 of the machine illustrated in FIG. 2, in order to transmit these vibrations to the drippers and to facilitate their insertion into the melt of the pipe. The vibrations applied on the ramp also make it possible to advance the drippers more evenly and to obtain a regular spacing of these drippers. These vibrations can be added, in another frequency band and / or in another direction, to the vibrations possibly used to advance the drippers along the ramp.

FIG. 3 illustrates a third embodiment in which the drippers 4 are pressed against the ramp 3 by means of a wheel 5 or a roller or ribbon bearing against the outer surface of the pipe. The wheel 5 can be motorized a no; its tangential speed, in the case of a motorized wheel, may be equal to that of the pipe, or slightly greater. In the case of a non-motorized wheel, its tangential speed will be equal to or slightly less than the longitudinal speed of the pipe.

FIG. 4 illustrates a fourth embodiment in which air or any other generally pressurized gas or fluid is fed into a channel 60 of the vibrator 6, for example a sonotrode, to create a lubricating film between the pipe 1 and the vibrator 6. In this way it is possible to reduce the friction between the vibrator 6 and the pipe 1 and subsequently the risk of tearing of the pipe 1. The pressure to which the air is subjected is light, for example less than 500 mbar, preferably less than 150 mbar. In other variants which are not illustrated, the air can also be brought by a channel 60 which does not belong to the vibrator 6, but which can for example and without limitation be part of the calibrator 2 and / or a other device not shown. In another variant, the total number of channels 60 is greater than one. These channels may belong to a single device, for example the vibrator 6, or to several devices, for example the vibrator 6 and the calibrator 2.

Reference numbers used in the figures

[0036] <tb> 1 <sep> Irrigation pipe <Tb> 2 <September> Calibrator <tb> 20 <sep> Portion of the sizer <tb> 3 <sep> Feeder feed system, eg boom, rollers, conveyor, vibrating track <Tb> 4 <September> Dripper <tb> 5 <sep> Wheel / roller / skid or support strap on the outside of the pipe <tb> 6 <sep> Vibrator, eg sonotrode, piezoelectric vibrator <tb> 60 <sep> Canal for the passage of air <tb> 7 <sep> Second vibrator <tb> d <sep> Longitudinal Direction <tb> C <sep> Drippers-hose contact point

Claims (24)

An irrigation pipe making machine comprising: an extrusion station (8); a calibrator (2); a dripper supply system (3) for bringing drippers (4) into contact with the inner surface of pipes (1) being cured at the outlet of the extrusion station; one or more elements (2, 3, 5, 6) in contact with said pipe (1) and / or with said emitters (4) in the calibrator (2) or downstream of the calibrator; characterized by a vibrator (6) for applying a vibration to one or more of said elements. 2. Machine according to claim 1, wherein the maximum frequency of vibration applied by said vibrator is greater than 500 Hz. 3. Machine according to claim 2, wherein the maximum frequency of vibration applied by said vibrator is greater than 20 KHz. 4. Machine according to one of claims 1 to 3, wherein the frequency of said vibration is adjustable according to the extrusion speed of the pipe (1). 5. Machine according to one of claims 1 to 4, wherein the vibration frequency applied by said vibrator (6) is distributed in a spectral band. 6. Machine according to one of claims 1 to 5, wherein said vibrations are applied in at least one direction substantially perpendicular to the extrusion direction (d). 7. Machine according to claim 6, wherein said vibrations are applied in at least a substantially radial direction relative to the pipe (1). 8. Machine according to one of claims 1 to 7, wherein said vibrations are applied in at least a substantially longitudinal direction relative to the pipe (1). 9. Machine according to one of claims 1 to 8, wherein said vibrations are applied simultaneously in several directions. 10. Machine according to one of claims 1 to 9, wherein said one or more elements to which a vibration is applied comprises a ramp (3) of said dripper supply system to bring the drippers (4) in contact with the face internal pipe (1). 11. Machine according to one of claims 1 to 10, wherein said one or more elements to which a vibration is applied comprises a support piece (2, 5, 6) outside said pipe (1) and against which the outer surface of the pipe is supported when drippers (4) are pressed against the inner surface of the pipe. 12. Machine according to one of claims 1 to 9, wherein said one or more elements to which a vibration is applied comprises said calibrator (2). 13. Machine according to claim 12, wherein a portion (20) of said calibrator (2) constitutes a bearing surface against which the outer surface of the pipe (1) rests when drippers (4) are pressed against the surface internal pipe. 14. Machine according to one of claims 1 to 13, wherein one or more elements (2, 3, 6) to which a vibration is applied is fixed. 15. Machine according to one of claims 1 to 13, wherein one or more elements (5) to which a vibration is applied is rotatable. 16. Machine according to one of claims 1 to 15, comprising a vibrator (6) common to apply a vibration to a plurality of said elements. 17. Machine according to one of claims 1 to 15, the distance between at least one of the elements subjected to vibration and the pipe (1) being adjustable. 18. Machine according to claim 17, the distance between at least one of the elements (6) subjected to vibration and the pipe being manually adjustable. 19. Machine according to one of claims 17 or 18, the distance between at least one of the elements subjected to vibration and the pipe being adjustable by means of an elastically compressible element and imposing a bearing force against said element. 20. Machine according to one of claims 1 to 19, wherein said one or more elements (2, 3, 5, 6) to which a vibration is applied comprises a Teflon surface, 21. Machine according to one of claims 1 to 20, wherein said one or more elements to which a vibration is applied is downstream of the calibrator (2) in a portion in which the extruded pipe (1) is not yet hardened. . 22. Machine according to one of claims 1 to 21, comprising a channel (60) for supplying a fluid to create a lubricating film between the vibrator (6) and the pipe (1). 23. Machine according to claim 22, said vibrator (6) comprising said channel (60), said fluid being a gas. 24. Method of manufacturing by extrusion of irrigation pipes comprising: extruding a pipe (1); calibrating the pipe (1) by means of a calibrator (2); feeding drippers (4) into contact with the inner surface of the pipe (1) during hardening; inside or downstream of the calibrator (2), in a portion of the pipe (1) being hardened, bringing the pipe and / or the drippers into contact with one or more elements (2, 3, 5, 6) ; applying a vibration to one or more of said elements,