Abstract
A method for producing an elongated product. By an extrusion unit, a material is extruded onto a core of the elongated product as a casing having a predetermined wall strength. Downstream of the extrusion unit and while the material is still moldable, the elongated product is supplied in a conveying direction to a molding unit. A portion of the material is held by the molding unit and, from the held material, a molded part is formed in an integral manner on the casing. The formation of the molded part is thereby carried out in an advantageous manner, via a deformation of material of the casing.
Claims
1. A method for producing an elongated product, which comprises the steps of: continuously conveying a core of the elongated product through an extrusion head of an extrusion unit; extruding, via the extrusion unit, a material with a constant flow rate onto the core in a form of a sheath with a predetermined substantially constant wall thickness; feeding the elongated product in a conveying direction to a molding unit downstream of the extrusion unit and while the material is still moldable; backing up in the conveying direction part of the material via the molding unit by displacing part of the material relative to a remaining part of the material resulting in backed-up material; and forming a molded part from the backed-up material in one piece on the sheath.
2. The method according to claim 1, which further comprises backing up the backed-up material in a backing-up region downstream of the extrusion head in the conveying direction with the molding unit.
3. The method according to claim 1, wherein the molding unit is closed to back up the material and is opened after formation of the molded part.
4. The method according to claim 1, which further comprises forming multiple molded parts at multiple, periodically recurring longitudinal positions.
5. The method according to claim 1, which further comprises receiving the backed-up material in a molding chamber of the molding unit and the molded part is formed in the molding chamber.
6. The method according to claim 5, which further comprises forming the molded part by filling the molding chamber with the backed-up material.
7. The method according to claim 1, which further comprises completely removing the sheath over a longitudinal portion of the elongated product using the molding unit and a free portion is thereby formed.
8. The method according to claim 7, wherein the elongated product is subsequently finished over the free portion.
9. The method according to claim 5, wherein the molding chamber is formed in that multiple mold cavities of the molding unit are brought together.
10. The method according to claim 9, which further comprises displacing the mold cavities to back up the material and in a brought-together state the mold cavities form the molding chamber.
11. The method according to claim 9, which further comprises mounting each of the mold cavities on a rotary element and the mold cavities are guided together and apart by rotation of the rotary element.
12. The method according to claim 9, wherein each of the mold cavities has a curved outer contour which forms a long molded part.
13. The method according to claim 9, which further comprises mounting each of the mold cavities by a displacement element and the mold cavities are displaced and/or rotated by means thereof at least to bring them together.
14. The method according to claim 9, which further comprises moving each of the mold cavities along a path which extends at least in places parallel to the conveying direction.
15. The method according to claim 14, which further comprises moving at least two of the mold cavities along a same straight portion and the at least two mold cavities have adjustable mold cavity spacing.
16. The method according to claim 15, which further comprises changing the adjustable mold cavity spacing when moving the at least two mold cavities.
17. The method according to claim 1, wherein the backing-up of the material is achieved by moving the molding unit in the conveying direction at a predetermined speed which is greater than a conveying speed of the elongated product, to form a rear molded part.
18. The method according to claim 1, which further comprises forming a regular elongated product portion which is free of molded parts between two successive longitudinal positions in the conveying direction.
19. The method according to claim 1, which further comprise temperature adjusting the molding unit on backing-up of the material.
20. The method according to claim 2, which further comprises temperature adjusting the molding unit prior to opening of the molding unit.
21. The method according to claim 1, further comprising providing the core as a cable core with a conductor for defining the elongated product as a cable.
22. The method according to claim 1, further comprising providing the core as a tube core for defining the elongated product as a tube.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
(1) FIG. 1 is an illustration showing an elongated product, which is guided through an extrusion unit and a molding unit for forming molded parts;
(2) FIG. 2A is an illustration showing a first variant of the molding unit for forming front molded parts on the elongated product;
(3) FIG. 2B is an illustration showing the use of the molding unit according to FIG. 2A to form rear molded parts;
(4) FIG. 3 is a front view of the molding unit according to FIG. 2A and of the elongated product;
(5) FIG. 4A is an illustration showing a second variant of the molding unit;
(6) FIG. 4B is an illustration showing a hybrid molding unit;
(7) FIG. 5 is an illustration showing portions of an elongated product with molded parts;
(8) FIG. 6 is an illustration showing a third variant of the molding unit;
(9) FIGS. 7A-7C are illustrations each showing a method step when using a fourth variant of the molding unit;
(10) FIG. 7D is an illustration showing a rotary element with mold cavities of a fifth variant of the molding unit;
(11) FIGS. 7E-7G are illustrations showing the method steps according to FIGS. 7A-7C with a sixth variant of the molding unit;
(12) FIG. 8A is an illustration showing a seventh variant of the molding unit;
(13) FIGS. 8B-8D are illustrations each showing a method step when using an eighth variant of the molding unit;
(14) FIGS. 9A-9F are illustrations each showing a variant of the elongated product in the form of a cable with a molded part; and
(15) FIG. 10 is an illustration showing a variant of the elongated product in the form of a tube with a molded part.
DETAILED DESCRIPTION OF THE INVENTION
(16) Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown the basic steps of a method according to the invention for producing an elongated product 2. FIG. 1 is a longitudinally sectional view of the elongated product 2 extending in a longitudinal direction L and containing an internal core 4 and a sheath 6 applied thereto. The elongated product 2 here takes the form of a cable, with a core, which accordingly is a cable core and for example contains one or more conductors, strands, wires and/or sub-cables. Alternatively, the elongated product 2 is a tube and the core 4 is then accordingly a tube core. In the exemplary embodiment shown here, the sheath 6 is in particular an outer jacket of the elongated product 2 whereas, in an alternative embodiment of the method, the elongated product 2 is further processed and is therefore produced as a semi-finished product. To apply the sheath 6, the core 4 is firstly fed in a conveying direction F to an extrusion unit 8. By means of the latter, a predetermined material, for example a plastics material, is extruded onto the core 4 as a sheath 6.
(17) In the conveying direction F a molding unit 10 to which the elongated product 2 is fed is connected downstream of the extrusion unit 8. In this case, in particular the conveying speed, i.e. here in particular the extrusion speed, and the distance A between the molding unit 10 and the extrusion unit 8 are selected such that the material of the sheath 6 is still moldable when it reaches the molding unit 10. By the molding unit 10, a part of the material of the sheath 6 is then backed up and used to form a molded part 12. In this way, the molded part 12 is formed directly from the sheath 6 of the elongated product 2.
(18) In FIG. 1, a molded part 12 embodied as a cylindrical thickened portion of the sheath 6 is shown by way of example. This is moreover only formed on a specific molded part portion A1 of the elongated product 2, which is adjoined by elongated product portions A2 with a sheath 6 of substantially uniform wall thickness W. In the exemplary embodiment shown here, a plurality of molded parts 12 are additionally formed at periodically recurring longitudinal positions, such that an elongated product portion A2 of a given length and in particular unaffected by the molding unit 10 extends between two molded parts 12 succeeding one another in the longitudinal direction L.
(19) A significant step of the method according to the invention is the backing-up of sheath 6 material by the molding unit 10. This operation is illustrated by way of example in a longitudinal sectional view in FIG. 2A with reference to a first variant of the molding unit 10. The molding unit 10 here contains two walls 16 displaceable in a displacement direction V, which walls form a gap-like aperture 18 with adjustable width B. The elongated product 2 and the extruded-on, still moldable sheath 6 thereof are then fed to the molding unit 10 in such a way that the elongated product 2 is passed through the aperture 18. If the width B of the aperture 18 is now smaller than the diameter D of the elongated product 2, then part of the sheath 6 material is caught at the walls 16 and backed up or accumulated there.
(20) Displacement of the walls 16 in the displacement direction V in this case determines whether or not backing-up takes place. To back material up, the walls 16 are in this case brought together in such a way as to bite into the sheath 6 and thereby form an obstacle for the material conveyed in the conveying direction F with the elongated product 2. In FIG. 2A the conveying speed of the elongated product 2 and the position of the molding unit 10, which is here fixed relative to the extrusion unit 8, result in a relative motion R of the molding unit 10 with regard to the elongated product 2 which is contrary to the conveying direction F. In this way, material is backed up upstream of the walls 16 in the conveying direction F, whereby in particular a front molded part 12a is formed. In a variant which is not shown, the molding unit 10 also moves contrary to the conveying direction F, whereby the relative motion R is accordingly boosted. In another alternative, additional motion in the conveying direction F also takes place, but at a lower speed than the conveying speed, such that a front molded part 12a is again formed but comparatively slowly. This is particularly advantageous at high conveying speeds and in particular if only a little material is to be accumulated.
(21) FIG. 2A shows the molding unit 10 in a closed state, in order accordingly to back up material. Once the molded part 12 is finished, the molding unit 10 is opened, i.e. transferred into an open state, and the molded part 12 is thereby released. In the exemplary embodiment shown in FIG. 2A, to this end the walls 16 are moved away from the elongated product 2 in the displacement direction V, such that they no longer bite into the sheath 6 and the accordingly accumulated material is automatically conveyed out of the molding unit 10 in the conveying direction F in the form of molded part 12, more precisely in the form of front molded part 12a, also known as a front part.
(22) An alternative use of the molding unit 10 according to FIG. 2A is shown in FIG. 2B. Here, the molding unit 10 is additionally moved in the conveying direction F, at a speed which is greater than the conveying speed of the elongated product 2. This results in a relative motion R between the molding unit 10 and the elongated product 2 in the conveying direction F, whereby sheath 6 material is accordingly pushed up downstream of the molding unit 10 to form the molded part 12 as a rear molded part 12b.
(23) FIG. 3 is a front view of the molding unit 10 of FIGS. 2A and 2B. Here the walls 16 are each mounted displaceably in a frame 20, resulting in the gap-like aperture 18. It is also clear that, in the closed state of the molding unit 10 shown here, the gap has a width B at least in the displacement direction V which is smaller than the diameter D of the elongated product 2 upstream of the molding unit 10 with the as yet unshaped sheath 6.
(24) FIG. 3 merely shows one particularly simple embodiment from a plurality of feasible and suitable embodiments of the molding unit 10 not shown here however. A molding unit 10 is for example alternatively used in which the edge of the respective wall 16 in each case facing the elongated product 2 is not straight, as here, but rather is configured for example to result in a circular or otherwise shaped aperture 18.
(25) FIG. 4A shows a second variant of the molding unit 10, in which it contains a plurality of, here two, mold cavities 22, which, as in FIGS. 2A and 2B, are displaced in a displacement direction V in particular perpendicular to the conveying direction F. By bringing together the two mold cavities 22, the molding unit 10 is then closed and a molding chamber 24 is formed, in which the backed-up material is collected as the elongated product 2 continues to be conveyed through the molding unit 10. In the exemplary embodiment shown, the molding unit 10 is kept closed until the molding chamber 24 is completely filled with backed-up sheath 6 material and then opened, such that a molded part 12 is formed with a defined contour predetermined by the molding chamber 24. Alternatively, the molding unit 10 is moved back before the molding chamber 24 has been completely filled with material.
(26) It is clear from FIG. 4A and also from FIGS. 2A and 2B that to form the molded part 12 the material of the sheath 6 is merely shaped and the backed-up material remains constantly joined to the remaining material not affected by the molding unit 10. This ensures a particularly good material bond between the molded part 12 and the rest of the sheath 6.
(27) FIG. 4B shows the molding unit 10 of FIG. 4A, wherein the spacing A between extrusion unit 8 and molding unit 10 is here zero, such that the extrusion unit 8 and the molding unit 10 are combined into a hybrid molding unit 27. In other words, the molding unit 10 is, as it were, integrated into the extrusion unit 8. The elongated product 2 is then fed first of all to an extrusion head of the extrusion unit 8 and there provided via ducts 8a with the material to form the sheath 6. The elongated product 2 then arrives directly at the molding unit 10, in which corresponding molded parts 12 are periodically formed, wherein the material advantageously has maximum moldability due to the tiny spacing A. In one alternative which is not shown, the ducts 8a are also connected with the molding chamber 24 of the molding unit 10 in order to supply further material or alternatively remove material during shaping.
(28) FIG. 5 shows a longitudinally sectional view of a portion of an exemplary elongated product 2. The elongated product 2 shown here contains a plurality of molded part portions A1, each with a molded part 12 here produced as a front molded part 12a, and elongated product portions A2 adjacent a respective molded part 12 and having a regularly embodied sheath 6. Furthermore, at the front of the molded parts 12 the sheath 6 has been completely removed in that the corresponding material has been backed up by the molding unit 10 and shaped into the molded part 12. In this way, the core 4, here in particular containing two strands 26, is here visible over a sheath-less free portion A3. At these free portions A3 the elongated product 2, initially manufactured as a continuous product, is preferably and particularly simply cut to length and divided into a plurality of elongated product pieces.
(29) FIG. 6 shows a third variant of the molding unit 10 for the method according to the invention. In this case, the molding unit 10 here contains two rotary elements 28, which are each rotatable about an axis of rotation DA, which extends perpendicular to the conveying direction F. The axes of rotation DA are here in particular parallel to one another. The elongated product 2 is then conveyed through between the rotary elements 28. At the circumference of a respective one of the rotary elements 28 a mold cavity 22 is in this case arranged for forming molded parts 12 from the material of the sheath 6. To this end, the rotary elements 28 are rotated about the respective axes of rotation DA thereof, such that the mold cavities 22 are each displaced along the circumference in a direction of rotation U. Through appropriate adaptation of the speed of rotation of the rotary elements 28 and the conveying speed of the elongated product 2, the relative motion R of the mold cavities 22 relative to the elongated product 2 is then adjusted. In one embodiment, through in particular continuous rotation a plurality of molded parts 12 are then formed with given predetermined longitudinal spacing from the sheath 6 of the elongated product 2, these molded parts being spaced accordingly from one another in the longitudinal direction L.
(30) The rotary elements 28 have a centerline distance AA perpendicular to the conveying direction F which is adjustable in the variant shown here. In other words, the rotary elements 28 are each displaceable relative to the elongated product 2, such that the mold cavities 22 travel as necessary towards the elongated product or are removed therefrom. The rotary elements 28 then serve during manufacture primarily in increasing production speed by carrying the mold cavities 22 with them. The relative spacing of two molded parts 12 is on the other hand determined by the time at which the rotary elements 28 are moved towards the elongated product.
(31) FIGS. 7A to 7C show a fourth variant of the molding unit 10 based on the arrangement according to FIG. 6. In this fourth variant a plurality of in particular different mold cavities 22 are mounted on a rotary element 28, by which mold cavities correspondingly different molded parts 12, here in particular front molded parts 12a and rear molded parts 12b, are then formed. To this end, the mold cavities 22 are moved towards the elongated product 2 by rotation in the corresponding direction and in this way different molding chambers 24 are formed, depending on the configuration.
(32) FIG. 7A, for instance, shows the formation of a front molded part 12a by bringing the corresponding mold cavities 22 together as shown. By conveying the elongated product 2 in the conveying direction F, backed-up material of the sheath 6 is then collected in the molding chamber 24 formed and in this way the molded part 12a is formed. By rotation in the circumferential direction U shown in FIG. 7B, the molding unit 10 is then opened and the elongated product 2 is conveyed unaffected thereby in the conveying direction F, to form a regular elongated product portion A2. The mold cavities 22 are thus moved along a path VB which here is circular.
(33) FIG. 7C then shows the formation of a rear molded part 12b by re-rotation in the same circumferential direction U and corresponding bringing together of the other two mold cavities 22. To back up the material, it is in particular necessary in this configuration of FIG. 7C to move the elongated product 2 relative to the molding chamber 24 contrary to the conveying direction F. This is achieved for example either in that during backing-up the rotary element 28 is rotated further, in such a way that the circumferential speed of the mold cavities 22 is greater than the conveying speed of the elongated product 2, wherein the conveying of the elongated product 2 is alternatively also interrupted, or in that the rotary elements 28 are fixed in the position shown in FIG. 7C and the elongated product 2 is conveyed back contrary to the original conveying direction F.
(34) FIG. 7D shows a rotary element 28 for a fifth variant of the molding unit 10, in which the mold cavities 22 are each mounted or suspended rotatably on the rotary element 28. In this way, parallel guidance of the mold cavities is achieved, so resulting in improved contact of the two mold cavities 22 which have been brought together during formation of a corresponding molding chamber 24.
(35) FIGS. 7E to 7G show a sixth variant of the molding unit 10 in which the mold cavities 22 are suspended rotatably, as in FIG. 7D, and additionally are also displaceably mounted. To this end, each mold cavity 22 is displaceable by way of a displacement element 30. In the exemplary embodiment shown here, the displacement elements 30 take the form of spring elements. When two mold cavities 22 are brought together, they are then displaced relative to the rotary element 28, resulting in corresponding deviation from the circular path and displacement of the mold cavities instead on a path VB which extends in places parallel to the conveying direction F, namely over a parallel portion PA. The mold cavities 22 are thus displaced as they approach the elongated product 2, here towards the axis of rotation DA, then guided along the parallel portion PA parallel to the elongated product 2 and subsequently raised again, wherein the displacement element 30 is moved back into the starting position. As a result of the additional rotatable embodiment of the mold cavities 22, advantageous parallel guidance is then achieved despite the rotating rotary elements 28.
(36) FIG. 8A shows a seventh variant of the molding unit 10 which is similar to the embodiments shown in FIGS. 6 and 7A to 7F in that here too mold cavities 22 are displaceable in a circumferential direction U by rotating rotary elements 28. The mold cavities 22 are here embodied in particular with a curved outer contour K, in order, to form a long molded part 12, to translate the rotation, i.e. displacement over a curved path VB, into a straight molded part contour.
(37) FIGS. 8B to 8D each show a method step for forming both a rear and a front molded part 12 by means of an eighth variant of the molding unit 10. The rotary elements 28 are here configured as chains, belts or conveyor belts in the manner of a caterpillar track, whereby the mold cavities 22 are moved on a substantially arbitrarily configurable path VB, which is roughly octagonal in the example shown. The path VB here contains a parallel portion PA, over which the mold cavities 22 are guided parallel to the elongated product 2, in particular in the brought-together state.
(38) In the example of FIGS. 8B to 8D two mold cavities 22 are moved in each case by means of one rotary element 28, wherein one of the cavities serves to form a front molded part 12a and the other to form a rear molded part 12b. In order additionally in particular to form a free portion A3, or alternatively an elongated product portion A2, between these two molded parts 12a, 12b, the two mold cavities 22 are displaceable relative to one another along the path VB. In other words, the mold cavities 22 mounted on a respective rotary element 28 display a mold cavity spacing FA relative to one another which is adjustable. One of the two mold cavities 22 is displaced, when brought together with the associated mold cavity 22 of the other rotary element 28, in the conveying direction F, such that the mold cavity spacing FA is enlarged and the free portion A3 is formed. The total of four mold cavities 22 thus form two molding chambers 24, which are displaced relative to one another.
(39) FIGS. 9A to 9F each show one exemplary embodiment of the elongated product 2 embodied as a cable, which elongated product was produced using the method according to the invention. The cables shown here merely by way of example each comprise a cable core, i.e. here core 4 with a plurality of strands 26 surrounded by a common sheath 6. Different molded parts 12 are in each case formed from the latter. For instance, FIG. 9A shows a disc-shaped or cylindrical molded part 12, while in FIG. 9B a conical molded part 12 is formed from the sheath 6. In FIG. 9C the molded part 12 is a sealing element with a circumferential groove 50, i.e. a peripheral groove, for example for insertion into a housing front, not shown. In FIG. 9D the molded part 12 takes the form of a thread. In FIG. 9E the molded part 12 comprises a plurality of fins 52 extending in the longitudinal direction L, which extend radially outwards from the sheath 6. Finally, FIG. 9F shows a recess 54 in the sheath 6 which was produced in particular by detaching the backed-up material partially or completely from the sheath 6.
(40) FIG. 10 shows an exemplary embodiment of the elongated product 2 taking the form of a tube produced using the method according to the invention. The tube shown here merely by way of example contains a core 4, i.e. here a tube core. This for example contains an inner sheath, not described in any greater detail, and braid applied thereto. In general in a tube the core 2 encloses a hollow space 46. A sheath 6 has been applied to the core 4, from which sheath a molded part 12 has been formed. Due to the underlying principle, those variants of the molded part 12 which are shown in FIGS. 9A to 9F may also be produced using an elongated product 2 in the form of a tube.
(41) The large number and variety of the exemplary embodiments of the elongated product 2 shown make it clear that virtually any desired molded parts 12 may be formed from the sheath 6 by appropriate shaping of the molding unit 10.
