IE50758B1

IE50758B1 - Sprinkler hose and method and apparatus for its production

Info

Publication number: IE50758B1
Application number: IE1740/80A
Authority: IE
Original assignee: Hegler Wilhelm
Priority date: 1979-08-17
Filing date: 1980-08-15
Publication date: 1986-07-09
Also published as: ZA804132B; IN152408B; EP0024622A1; GR69803B; DK352780A; CA1168012A; EP0024622B1; IL60522A0; DE3066979D1; DD152615A1; DE2933304A1; JPS5637126A; ATE6570T1; IE801740L; ES252578U; ES252578Y; MA18932A1

Abstract

1. Method of manufacturing a water hose having inner intermediate walls using a mould which is moved along a mould run and consists of endlessly guided mould halves which, when moving into the linear mould run, are guided in pairs towards one another and closely adjacent to one another in the direction of movement while the mould is closed, and a still thermoplastic hose being fed to the mould and deformed therein under a vacuum, characterised in that, even before two mould halves are moved together, the hose is subjected to a vacuum at least in part of its cross-section, at least one vacuum channel extending into the run-in area of the mould halves as far as the front of the linear mould run so that at least one vacuum hole overlaps the vacuum channel before the mould is closed, and, subsequently, is compressed over part of its cross-section leaving hollow spaces open to form weld marks.

Description

Bie invention relates to a method and apparatus for producing sprinkler hoses. German published Patent Application No. 28 35 117 describes a sprinkler hose formed in one instance from a two-layer folded plastic sheet and in another instance iron a continuous tube. The hose is then provided with a longitudinal seal which defines transverse openings. A portion of the hose which constitutes a drip section is provided with trickle openings through which the water emerges in droplets. Furthermore, associated with each connecting opening and each trickle opening are short welded seals or spot welds which throttle the flow of water so that the volume of water flowing through the trickle openings is relatively small. The sprinkler hose described in the afore-mentioned publication is intended for the purpose of so-called trickle sprinkling and is relatively simple to manufacture. However, it is practically impossible to produce a hose in which the pressure drop along the path from the one or more connecting openings up to the trickle openings remains well-defined. Accordingly, the required throttling can be obtained only by making the trickle openings very small, i.e., with very minute cross sections. However, in operation these openings tend to become enlarged so that the rate of water release per unit length of hose becomes very non-uniform over the length of a given sprinkler hose. 80758 - 3 Another type of sprinkler hose is described in German published Patent Application No. 27 16 365 in which the entire length of the hose serves to supply water and in which a fold of the hose wall is separated frcm the remainder of the hose by welded seams and contains capillary water lines. As before, the problem of maintaining a precisely defined pressure drop in the capillary lines up to the water outlet exists in this exanpie.

Still another hose for trickle sprinkling is described in German published Patent Application No. 26 57 695. This publication describes a hose consisting of a first tube made frcm a sheet and a secnd tube which contains meandering channels and is welded to the first tube. The meandering channels ccmnunicate at one end with the interior tubing and have a trickle opening at the other end. The hose described in this publication is produced by guiding a sheet of material over a vacuum deep-drawing roller which has a vacuum zone in a portion of its circumference. The sheet material is pulled into given depressions of the roller when passing through the vacuum zone. Subsequently, the formed sheet is welded to a second sheet. This method of production is not economical for large-scale manufacture because the roller must not only deform and weld the material but must also cool it off. Such a roller would have to be of extraordinarily large dimensions to serve for a sufficient rate of mass production.

Still another sprinkler hose is known frcm German published Patent Application No. 26 30 07S and consists of an inner smooth tube surrounded by an outer tube containing helical channels. The inner tube has connecting openings and the outer tube has trickle openings. In principle, the spiral channels serving to decrease the pressure as between the connecting openings and the trickle openings are very suitable, but they are very difficult to produce in the required small tube diameters. A tube such as is described in German published Patent Application No. 26 30 078 may be produced, for example, by an apparatus described in German published Patent Application No. 20 61 027.

It is a principal object of the present invention to provide a S07S8 - 4 method and an apparatus for producing sprinkling hose in a continuous working process.

According to the invention, there is provided a method for manufacturing a sprinkler hose having internal open chambers, the method including the use of a mould line consisting of endlessly guided mould section halves, pairs of mould section halves being guided towards one another at the inlet of said mould line and thereafter closed and guided axially along said mould line in contact with one another, and the method also including the guiding of still warm and plastic hose into said mould line for deformation therein by the application of vacuum, wherein vacuum is applied to at least part of the cross-sectional area of the hose prior to two mould section halves being closed, at least one vacuum channel of the mould line being so positioned that when a pair of said mould section halves are guided towards one another and brought into said contact, at least one vacuum bore of each mould section half is aligned with said vacuum channel prior to said mould section halves being closed, and said hose is subsequently compressed over a portion of its cross-sectional area, thereby leaving said open chambers while forming weld locations. Said vacuum is suitably applied to the still warm and plastic hose substantially in the cross-sectional area thereof fran which a trickle region will be formed, thereby deforming said region. In this manner, the still warm and plastic hose is preformed by the application of vacuum prior to the mould being closed. This step of the method is of great importance because the hose has a large number of welded joints especially in the vicinity of its trickle region. If the hose were not subjected to prior vacuum suction, this welding would cause the walls of the hose to adhere to each other over the full length and width of the trickle region, ftie prior application of vacuum prevents such overall adhesion and permits adhesion only where subsequent welding is actually intended. However, the prior application of vacuum takes place only a very short time before mould closure. In particular, the vacuum application may start between 0.03 and 0.10 seconds prior to said mould section halves being closed. Vacuum may also be applied to the exterior of the still warm and plastic hose substantially in the cross-sectional S0758 area thereof from which a supply region will be formed, and, in order to prevent that part of the still warm and plastic hose which is to form the water supply region from being squeezed in between the closing mould halves, this part of the hose is subjected to vacuum only after said mould section halves have been closed. In order to enhance the preforming of the still warm and plastic hose, support air at low pressure may be applied to the interior of said still warm and plastic hose. In particular, the pressure of said support air may lie between 0.01 bar and 0.05 bar.

In order to ensure that the still warm and plastic hose enters the mould correctly, the method of manufacture according to the invention may also provide for the still warm and plastic hose to be pressed together and flattened prior to the application of vacuum.

In another aspect, the invention also provides apparatus for carrying out the method of the invention, said apparatus including a mould line having a mould table on which trains of mould section halves are endlessly guided, pairs of mould section halves being moved into juxtaposition at the entry into said mould line and consecutive mould sections being moved axially in said mould line in close proximity, each of a pair of said mould section halves being provided with internal cavities which define the profile to be imparted to the object to be moulded, each of said pair of the mould sections halves having at least one vacuum bore which connects said internal cavities with the underside of the mould section half, and at least one vacuum channel being provided in said mould table of the apparatus for connection to said vacuum bores when aligned therewith, wherein said at least one vacuum channel is so positioned that when a pair of said mould section halves are brought into juxtaposition, said at least one vacuum bore of each mould section half is aligned with said vacuum channel prior to said mould section halves being closed. By suitable construction and positioning of the cooperating vacuum bores and channels, only a particular region, i.e., the region in which the trickle section is formed in the still warm plastic hose, will be subjected to vacuum for the purpose of preforming.

In order to provide for subsequent application of vacuum to other parts of the mould, the apparatus may also contain secondary 507S8 - 6 independent vacuum bores which cooperate with different parts of the mould and which are subjected to vacuum at a time later than a first set of vacuum bores.

In particular each mould section half may have at least two groups of mutually independent vacuum bores, each connected to different parts of said internal cavities, and each said group of vacuum bores is then associated with a different vacuum channel of said mould table. Hie vacuum bores of one of said groups may provide connection between said internal cavities and the respective said vacuum channel of the mould table prior to said mould section halves being closed and said vacuum bores are then closer to the corresponding vacuum bores of the associated mould section half of said pair of the mould section halves than are the vacuum bores of the other of said groups, while the vacuum channel of the mould table associated with said other group of vacuum bores may be defined by an enlargement of the vacuum channel associated with said one group of vacuum bores.

The apparatus of the invention provides for production speeds of up to 30 meters of finished sprinkler hose per minute. It has been found to be particularly favourable for the purposes of the invention if the wall thickness of the sprinkler hose is between 0.3 and 0.5 millimeters. This low thickness also substantially reduces the material expenditure for a given length of sprinkler hose.

Other advantages and characteristics of the invention will emerge iron the description of preferred exemplary embodiments which relate to the drawings.

In the drawings: Fig. 1 is a partial top view of a moulding machine according to the invention for producing sprinkler hose, along the line XV-XV in Fig. 3; Fig. 2 is a vertical section through the apparatus of Fig. 1 along the line XVI-XVI; Fig. 3 is a vertical section through the apparatus of Fig. 1 along the line XVII-XVII; Fig. 4 is vertical section through the apparatus of Fig. 1 along the line XVIII-XVIII; and Fig. 5 is a vertical section through the apparatus of Fig. 1 along the line XIX-XIX. 80758 - 7 An apparatus according to the invention for manufacturing sprinkler hose is illustrated in part in Figs. 1-5. The basic construction of this apparatus may be similar to that described in German Published Patent Application No. 20 61 027.9-16. This apparatus includes a plurality of mould halves 34, 35 which are guided on a pair of endless tracks and in which pairs of mould halves 34, 35 approach one another and finally join together to define a hollow mould section within which a length of sprinkler hose is formed. The overall cross section of the mould halves 34, is rectangular and the mould halves are guided over the surfaces of a flat machine table 37. The opposing faces 38, 39 of the mould halves 34, 35 are appropriately configured to define one-half of the external profile of the sprinkler hose to be formed therein. At the start of the moulding line 36, the piairs of mould halves 34, 35 pivot towards one another. Also located in this area of the mould line is the extrusion nozzle 40 of a plastics extruding machine, not shown in further detail and assumed to be of known construction, frcm which emerges a substantially cylindrical plastic hose or tube. Pivotably disposed on or near the extrusion nozzle are two pivotal arms 42, 42' which rotate around vertical bolts 41 and which are adjustable. The free ends of the arms 42, 42' carry rollers 43 which can turn around vertical axes 44. The rollers 43 serve to inpart sane flattening to the previously circular hose 45 emerging from the extrusion nozzle 40. The rollers 43 are also used to adjust the wall thickness of the hose 45 being extruded by appropriate adjustment of the direction of flow. At the outset, the pivotal arms 42, 42' carrying the roller 43 are placed in the retracted position shown in dash-dotted lines in Fig. 1. Only after the hose being extruded with substantially circular cross section has been grasped by the mould halves 34, 35 and has been guided into the mould line are the pivotal arms 42, 42' moved inwardly, thereby causing a deformation and adjustment of the hose 45. Thereafter, the bolt 41 is fixed and the pivotal arms 42, 42' are fixed in their operative position. The width of the flattened hose 45' is smaller than the width of the finished sprinkler hose 1 (Figs. 3, 4, 5). An air channel 47 within the extrusion core 46 of the extrusion nozzle - 8 40 carries air at a very low pressure of approximately, for example, 0.01 - 0.05 bar, which serves to maintain and correct the profile of the flattened hose 45'.

The mould halves 34, 35 are so displaced as to assume an initially parallel relative position subsequent to entry into the mould line 36. In that position the now parallel mould halves 34, are farther apart than the width of the flattened hose 45'. In this position, the corresponding mould halves 34, 35 are engaged by respective parallel rails 49 which guide the mould halves into closer and closer juxtaposition. As will be seen from Fig. 1, the end faces 50, 51 of the various pairs of mould sections 34, 35 are in immediate and planar contact with one another in the mould line. The moulds composed of mould halves 34, 35 are advanced along the guide rails 49 until the faces 38, 39 are in direct contact. Subsequently, they are guided in straight lines by guide rails 52 that are extensions of the guide rails 49.

As best seen in Fig. 3, each of the mould halves 34, 35 is provided with a vacuum bore 53 which extends down to the bottcm face 55 adjacent to the top of the machine table 37. The bores 53 closest to the adjacent faces 38, 39 communicate through openings 56 in the shape of elongated slots with the central region of the mould recess 57 in which trickle regions 3 and adjacent transition regions 7 of a sprinkler hose are formed.

The top of the machine table 37 contains open vacuum channels 58 which are overlapped by the aforementioned vacuum bores 53 when the mould halves 34, 35 are pushed together by the parallel guide rails 49 into a position in which they are still separated. At that time, the vacuum bores 53 and thus the openings 56 are subjected to a vacuum with the consequence that the central region of the hose 45' is urged against the sides 38 and 39 of the mould halves 34, 35, respectively, in the area of the mould recess 57. This process causes a preforming of the hose in the central region. The entire top of the vacuum channels 58 is covered by the mould halves 34, 35 when vacuum is applied so that no external air enters these channels. The vacuum may be produced by known and customary means. The side walls 4 and 5 (Fig. 4) of the tube cannot therefore adhere to one another.

SO758 - 9 The mould halves also contain exterior vacuum bores 54, as best seen in Figs. 4 and 5, which communicate with transverse bores 60 closed externally by plugs 59 which in turn communicate with elongated slots 61 that enter the upper and lower regions of the mould recess 57 in which supply regions 2 of the sprinkler hose are formed. The associated vacuum channels 54 are subjected to vacuum at the time when the two mould halves 34, 35 are in direct and immediate contact, i.e., when the faces 38, 39 touch, as shown in Fig. 4. The application of vacuum takes place by the movement of the mould halves over a part of the machine table in which the vacuum channels 58 are widened to define vacuum channels 62. This application of vacuum causes the final shaping and moulding of the supply regions 2 of the hose frcm the position shown in Fig. 4 into the position shown in Fig. 5, although the degree of final deformation is substantially less in the vertical direction than would appear to be the case frcm Fig. 4 which is exaggerated for illustration. The actual deformation in the vertical direction is no greater than approximately 1-2 millimeters. In the position of the mould halves illustrated in Fig. 4, i.e., when they are in direct contact, walls 17, 18 of the hose are welded together in the area of the trickle regions 3 at weld locations 19 and 20.

An alternative method of guiding the mould halves 34, 35 into a mutually parallel position is described in German Patent Application 28 32 350.4 and may be used instead of that according to German Published Patent Application 20 61 027.

Claims

1. A method for manufacturing a sprinkler hose having internal open chambers, the method including the use of a mould line consisting of endlessly guided mould section halves, pairs of mould section halves being guided towards one another at the inlet of said mould line and thereafter closed and guided axially along said mould line in contact with one another, and the method also including the guiding of still warm and plastic hose into said mould line for deformation therein by the application of vacuum, wherein vacuum is applied to at least a part of the cross-sectional area of the hose prior to two mould section halves being closed, at least one vacuum channel of the mould line being so positioned that when a pair of said mould section halves are guided towards one another and brought into said contact, at least one vacuum bore of each mould section half is aligned with said vacuum channel prior to said mould section halves being closed, and said hose is subsequently compressed over a portion of its cross-sectional area, thereby leaving said open chambers while forming weld locations.

2. A method according to claim 1, wherein said vacuum is applied to the still warm and plastic hose substantially in the cross-sectional area thereof from which a trickle region will be formed, thereby deforming said region.

3. A method according to claim 1 or claim 2, wherein said application of vacuum starts between 0.03 and 0.10 seconds prior to said mould section halves being closed.

4. A method according to any preceding claim, wherein vacuum is also applied to the exterior of the still warm and plastic hose substantially in the cross-sect/enal area thereof from which a supply region will be formed, said vacuum being applied only after said mould section halves have been closed.

5. A method according to claim 4, wherein said application of vacuum to said cross-sectional area of the hose fran which said supply region will be formed starts between 0.03 and 0.10 seconds after said mould section halves have been closed. - 11

6. A method according to any preceding claim, wherein support air at low pressure is applied to the interior of said still warm and plastic hose.

7. A method according to claim 6, wherein the pressure of said support air lies between 0.01 bar and 0.05 bar.

8. A method according to any preceding claim, wherein said still warm and plastic hose is flattened prior to the application of vacuum thereto.

9. Apparatus for carrying out the method according to claim 1, said apparatus including a mould line having a mould table on which trains of mould section halves are endlessly guided, pairs of mould section halves being moved into juxtaposition at the entry into said mould line and consecutive mould sections being moved axially in said mould line in close proximity, each of a pair of said mould section halves being provided with internal cavities which define the profile to be imparted to the object to be moulded, each of said pair of the mould section halves having at least one vacuum bore which connects said internal cavities with the underside of the mould section half, and at least one vacuum channel being provided in said mould table of the apparatus for connection to said vacuum bores when aligned therewith, wherein said at least one vacuum channel is so positioned that when a pair of said mould section halves are brought into juxtaposition, said at least one vacuum bore of each mould section half is aligned with said vacuum channel prior to said mould section halves being closed.

10. Apparatus according to claim 9, therein each mould section half has at least two groups of mutually independent vacuum bores, each connected to different parts of said internal cavities, and each said group of vacuum bores is associated with a different vacuum channel of said mould table.

11. Apparatus according to claim 10, therein the vacuum bores of one of said groups provide connection between said internal cavities and the respective said vacuum channel of the mould table prior to said mould section halves being closed and said vacuum koref - 12 are closer to the corresponding vacuum bores of the associated mould section half of said pair of the mould section halves than are the vacuum bores of the other of said groups, and the vacuum channel of the mould table associated with said other group of vacuum bores is 3 defined by an enlargement of the vacuum channel associated with said one group of vacuum bores.

12. A method for manufacturing a sprinkler hose, substantially as described herein with reference to and as shown in the accompanying drawings. 10

13. Apparatus for manufacturing a sprinkler hose, substantially as described herein with reference to and as shown in the accompanying drawings.

14. Sprinkler hose manufactured according to the method of 15. Any of claims 1 to 8, or that of claim 12.

15. Sprinkler hose manufactured using apparatus according to any of claims 9, 10, 11 and 13.