Extruder head.

p0001The invention relates to an extrusion head for extruding tubular or tubular preforms made with a single- or multi-layer wall construction in extruders plasticized plastic material.

p0002It is known single- or multilayer plastic container in the blow molding of tubular or tubular preforms produce that are extruded using known extrusion heads of extruders in plasticized plastic material.

p0003While doing the preforms for containers with a single-layer wall construction can be manufactured without any problems, it often caused difficulties, with multilayer wall structure to extrude preforms so that the therefrom produced by the blow-molding plastic containers have a faultless condition.

p0004Be in the extrusion of preforms all concentric with each other are formed with multi-layer wall structure, these layers at approximately the same level, this results in that in each case the outer layers of initially extruded in a very large diameter and must then be compressed under insertion of elastic circumferential deformations on the subsequent pipe diameter, while the innermost layer with the smallest diameter is subject to the distribution system a much lower Umfangsde formation, because they have to change their diameter only relatively slightly. It is because - especially when different plastics are extruded into a laminar structure - often before, that cause the layers poor adhere to each other and thereby inadequate product characteristics in terms Stauchdruck- and / or drop strength.

p0005But disadvantage is also the relatively large diameter of each extrusion head so that it can be difficult to operate as a multiple extrusion heads side by side.

p0006To avoid these disadvantages, although it is also possible to set the distribution systems for the construction of the individual wall layers in the extrusion head in a row. However, this structure has the result that the length of the extrusion head in dependence on the number of layers to be set up wall varies considerably and that thereby provide a long flow path for the plastic material in the individual layers.

p0007So while bie the first-described type of extrusion heads may an extreme variation of the diameter ratios in the individual layers, resulting in the case of another type extreme variations of the flow times, dwell times and shear stresses for the individual layers.

p0008Purpose of the invention is to avoid the known types of extrusion heads inherent shortcomings. It is therefore the object of the invention to provide an extrusion head of the initially unspecified genus, which enables one hand small diameter variations between individual layers NEN but then also undesirably long flow paths or dimensions avoids the extrusion head.

p0009This object is achieved by the identification features of claim 1, characterized in that the same or similar head portions each having a central annular outlet and / or passage are selectively hintereinandersetzbar that each of these head portions at least one with an annular gap in the outlet and / or passage includes leading-helix distributor, and that the mutually facing ends of adjacent head portions complementary to each other having mating engagement elements, of which the exit and / or passage channels are brought into axial alignment.

p0010Since certain common flow path lengths of adjacent plastic layers are advantageous in terms of the best possible connection or welding, can be based on these characteristics create extrusion heads wearing satisfy individual needs.

p0011according to claim 2, the invention proposes that each head portion is equipped with up to three concentrically one seated spiral mandrels concentric sit together and all open into the outlet and / or passage of it containing the head portion. With a single head portion relatively short length so can extrude preforms that have a one- to three-layer wall construction. Two successively set head portions enable the production of preforms with two to six layers of the wall, while by the use of three series-set head sections, the manufacturing of preforms permits which have from three to nine layers of the wall.

p0012By verschidenartige combination of head sections can thus be relatively little technical effort to adapt to the different conditions reach.

p0013According to another important training aspect of the invention is provided according to claim 3, that each head portion carries a tail that has a number of spiral distributor includes corresponding number of connection and supply channels for the plasticised plastics material.

p0014These tails can be doing, angularly offset circumferentially connecting the extruder for the different plastic materials.

p0015In many cases it proves to be recommended, according to claim 4 between two identical or similar head portions employ a merely provided with a passageway head portion, thereby already to establish common flow lengths laminarisierter melt layers, thereby improving the adhesion between them.

p0016according to claim 5 it is in accordance with the invention, however, also possible that the outlet is preceded by a merely provided with a passageway head portion to provide there for all laminarisierten melt layers a common flow path.

p0017It is particularly advantageous to further, if up to three identical or similar head portions are successively switched according to the teaching of claim 6, each with at least one spiral distributor. The total length of the extrusion head thereby exceeds three times the diameter only slightly. However, it can be extruded with an extrusion head such preforms to have up nine overlapping layers.

p0018As proven expedient has for some cases, a structure according to claim 7, which means that the number of spiral distributor decreases in the series-connected head portions toward the outlet nozzle towards. This will not have namely often reologisch-thermodynamic advantages.

p0019according to claim 8 is the invention is also the possibility that the spiral distributors are mutually fitted by the head portion and / or thermally insulated, whereby they can be provided with or connected according to claim 9 with independent tempering. It is then possible to effect a different temperature control of the moved by the single spiral distributor melt streams and thereby to influence the different materials to be processed plastic optimal. So it may be useful to feed plastics materials with very different temperatures after extrusion into the extrusion head, and also to keep them in the distribution of material at this temperature to allow temperature compensation only in the layered extrudate.

p0020In terms of structure, according to claim 10 Finally, provided that the spiral distributor each consist of sleeves which a weak conical outer section of great length and a steep conical end short length have on their outer coat, while her inner shell is executed on the entire length cylindrical.

p0021Further features and advantages of the subject matter of the invention are explained below on guide examples shown in the drawing. Show it<ul><li>Figure 1 in longitudinal section an extrusion head, which is composed of three identical head sections,</li><li>2 shows a view of the extrusion head of Figure 1 in the direction of arrow II,</li><li>3 shows a section along the line III-III through the extrusion head of Figure 1,</li><li>4 shows a section along the line IV-IV through the extrusion head of Figure 3,</li><li>5, the three head sections of the extrusion head of Figure 1 in a separated state from each other, while the</li><li>Figures 6 and 7 reflect in a purely schematic longitudinal section of training options for an extrusion head.</li></ul>

p0022In Figure 1 of the drawings, an extrusion head 10 is shown in longitudinal section for extruding tubular or tubular preforms, which for example consists of three identical head sections 11, 12 and 13, which are set with axial alignment one behind the other. At the front head portion 13 of the extrusion head 10 thereby the outlet 14 connects whose nozzle needle 15 coaxially carried out by all the head portions 11 to 13 and can be actuated by the end of the rear head portion 11 ago.

p0023All head portions 11, 12, 13 of the extrusion head 10 have at least a similar basic structure.

p0024The head portion 11 has a casing body 16 which is provided over the major part of its length with a cylindrical inner lateral surface 17, but has a conical taper 18 at its front end. This conical taper 18 runs on the end face 19 of the shell body 16 into a central orifice 20th

p0025From the rear end of the head portion 11 from projecting into the casing body 16 is a sleeve body 21 coaxially into it, which protrudes from a mounting flange 22, and at least approximately flush its free end 23 with the end surface 19 of the jacket body 16 to communicate with its mouth opening 20 an annular outlet channel 24 limit.

p0026The sleeve 21 has a central Durchgangslock 25 for the nozzle needle 15. At its outer periphery, the sleeve 21, at least over most of its length a towards the free end 23 toward weak tapered shell section 26, which in turn shortly before the free end 23 a waist-like constriction 27 contains.

p0027In the shell portion 26 of the sleeve 21 helically extending melt channels 28 are incorporated, which adjoin an axis parallel to the longitudinal axis of the sleeve 21 extending melt supply channel 29 and which have a different tread depth. The tread depth of the melt channels 28 takes namely in the direction from the mounting flange 22 of the sleeve 21 away from the free end 23 thereof towards steadily, as can be clearly Figures 1 and 5 taken.

p0028The retaining flange 22 for the sleeve 21 is releasably connected together with an end piece 30 via screws 31 to the casing body 16, in such a way that the supply channel 29 passes over to the melt in a connection channel 32, which opens laterally on the Entstück 30 and the connection for an extruder forms.

p0029At the free end 23 are 25 widenings 34 and 35 are formed relative to the cross-section of the through hole, said widening having smooth mating surfaces 34 while the other widening 35 is equipped with an internal thread 36th

p0030The protruding from the mounting flange 22 sleeve 21 is coaxially surrounded by a further sleeve 37, which is centered on the rear, cylindrical shell portion 38 and has a cylindrical inner shell 39 over its entire length.

p0031The cylindrical inner shell 39 of the sleeve 37, together with the weak conical outer jacket 26 of the sleeve 21 a so-called spiral distributor 40, which determines an annular passage 41 for the melt, in which the melt moving gradually from the so-called spiral flow in the melt channels 28 in an axial flow the free end 23 of the head portion 11 toward transferred.

p0032The outer casing 42 of the second sleeve 37 is designed in a similar way as the outer casing 26 of the first sleeve 21. It has namely towards the free end slightly tapered shape, has in its rear portion melt channels 43 whose tread depth in the direction from the back to forward steadily decreases and is provided near its free end with a waist-like constriction 44th

p0033Notwithstanding the sleeve 21, the sleeve 37 is provided at its free end with a steeply tapered end portion 45, whose outer surface is 46 adjacent to form a conical annular gap 47 of the conical inner surface 18 of the jacket body 16th

p0034The second sleeve 37 is concentrically surrounded by a third sleeve 48 which protrudes from a mounting flange 49, with which the second sleeve is a part 37 releasably connected by bolts 50 and on which the other hand, the third sleeve 48 by the screws 31 to the casing body 16 and the end piece 30 is in the holding connection.

p0035The third sleeve 48, in turn, almost over their entire length a cylindrical inner shell 51, which is effective together with the conical outer jacket 42 of the second necks 37 as spiral distributor 52, which includes an annular melt channel 53 within which the original spiral flow converted into an axial flow is, before the melt then passes into the conical annular gap 47 and moves toward the outlet duct 24th

p0036The outer casing 54 of the third sleeve 48 is in turn over most of its length in the direction towards the free end designed slightly conically tapered, but it also has at its free end a steeply tapered end portion 55, whose outer surface 56 of the conical outer surface 18 in the casing body 16 opposite to form a gap spacing 57th In the vicinity of the retaining flange 49, however, the third sleeve 48 has a cylindrical skirt portion 58 which protrudes suitable for centering in the cylindrical inner circumference of the jacket body sixteenth

p0037Also in the outer casing 54 of the third sleeve 48 to melt channels 59 located with in the direction toward the free end steadily tapered tread depth, said outer jacket 54 engages the inner cylindrical portion 17 of the jacket body 16 as a so-called spiral distributor 60, the one toward the free end limited towards flared annular gap within which the spiral flow of the melt gradually into an axial flow, before the gap 47 passes through the gap 57 and into the region of the annular outlet channel 24th

p0038It should be mentioned that the melt channels 43 of the second sleeve 37 are connected to a supply channel 62 in connection, which goes from the sleeve 37 by the retaining flange 49 and the mounting flange 22 in the end piece 30 and opens laterally there can like 2 see ,

p0039A similar feed channel 63, the melt is also the melt channels 59 assigned in the third sleeve 48, as can be seen easily from FIGS. 1 and 2

p0040The structure of the head portion 12 at the extrusion head 10 of Figure 1 corresponds with respect to the casing body 16 and the coaxially therein recorded another two sleeves 37 and 48 practically completely the head portion 11th

p0041A deviation from the head portion 11, however, is that the head portion 12 is an inner sleeve 64 includes a central passageway 65 for the nozzle needle 15, which is otherwise arranged and formed, as the sleeve 21 in the head portion 11th

p0042The sleeve 64 in the head portion 12 is formed relative to the other parts of loose, that is, they can coaxially through the sleeve 37 as well as the end piece 66 of the head portion 12 be passed. They defined between the outer periphery thereof, the inner surface of the sleeve 37 and a passageway 67 in the end piece 66 an annular passage 68 for the coming from the outlet channel 24 of the head portion 11 of molten. The passage 68 serves two stepped up to today stepped longitudinal sections 69 and 70 which extend to each slightly tapered by corresponding peripheral design of the outer jacket of the sleeve 64 in the direction of passage of the melt strand.

p0043The rear end 71 of the sleeve 64 projects from the rear end of the end piece 67 and is there provided with peripheral gradations 72 and 73rd While the scope of gradation 72 a smooth-faced Passungsstufe which may correspond to the sleeve 21 with the smooth-faced Passungsstufe 34, the peripheral step 73 is provided with an external thread 74 which matches the internal thread 36 in the sleeve 21 of the head portion 11th

p0044The other end of the sleeve 64 has a matching with the free end of the sleeve 21 of the head portion 11 embodiment, therefore contains step-like extensions 75 and 76 opposite the central passage 65, of which the gradation has 75 smooth close-fitting, while the gradation 76 with internal thread 77 is provided. The outer circumferential surface of the sleeve 64 is limited at the free end 78 of the sleeve with the end portion 20 of the sheath body 16 has an annular outlet channel 79 for the melt, in which the annular gap 57, 47 from radially opens outwardly formed between the conical inner surface 18 of the jacket body 16 and the conical end sections 55 and 45 of the two sleeves 48 and 37 is determined.

p0045The head portion 13 of the extrusion head 10 of Figure 1 has a shell body 80 whose inner circumferential surface includes a cylindrical main portion 81 and a tapered end portion 82, which opens into a passage 83 at the free end of the 84th From rear end protrudes into the casing body 80 a sleeve 85, which protrudes from a mounting flange 86, which is connected with an end piece 87 by screws 88 to the casing body 80th

p0046The sleeve 85 is then in a cylindrical passageway 89, which connects to a corresponding cylindrical passageway 90 in the end 87th

p0047The outer shell of the sleeve 85 has a weak tapered shell section 91 and an adjoining steep conical end 92, whose outer surface facing 93 to form an annular gap 94 of the conical outer surface 82 in the casing body 80th The conical annular gap 94 opens it out immediately before the outlet opening 83rd The conical skirt portion 91 of the sleeve 85 is provided with an incorporated melt channel 95 whose profile depth towards steadily decreases towards the free end of the sleeve, as do the figures 1 and 5 significantly. The melt channel 95 is supplied via a connecting channel 96 to the next by an extruder melt. For this purpose, the connecting channel 96 by the retaining flange 86 and the end piece 87 is guided so that it opens out in the latter sideways. The inner circumferential surface 81 of the shell body 80 and the outer surface of the sleeve 85 together form a spiral distributor 97 for the melt, which encloses a in the flow direction in a wedge shape widening annular gap 98, in which the melt flow rate is gradually converted from a spiral flow in an axial annular flow before passing through the conical annular gap 94 before the outlet opening 83rd Concentrically with the sleeve 85, a sleeve 99 is in the head section 13 also provided that includes a smooth cylindrical passageway 100 for the nozzle needle 15, as well as a cylindrical outer casing 1 has. From cylindrical inner casing 89 of the sleeve 85 and the cylindrical outer casing 101 of the sleeve 99 an annular cylindrical passageway 102 is limited, which continues even through the end piece 87 therethrough.

p0048The rear end of the sleeve 99 projects beyond the rear end of the end piece 87 and is there provided with peripheral paragraphs 103 and 104th The scope of paragraph 103 is designed as a smooth-surfaced Passungsabsatz while the peripheral ledge 104 has an external thread 105th

p0049In the same way as the sleeve 64 of the head portion 12 with the sleeve 21 of the head portion 11 can be connected by screwing, can therefore be put 12 in holding connection and the sleeve 99 of the head portion 13 with the sleeve 64 of the head portion, as apparent from Figure 1 apparent.

p0050The front end 106 of the sleeve 99 has in turn in relation to the passage 100 stepwise advanced recesses 107 and 108, of which the former is provided with smooth-walled fitting surfaces, while the second contains an internal thread 109.

p0051The front end 106 of the sleeve 99 lies at least approximately at the same level with the free end 84 of the head section 13 and limits there along with the passage opening 83 an annular outlet channel 110, opens into the outward from radially the conical annular gap 94th

p0052The head portion 11 of the extrusion head 10 of Figure 1 has a structure which allows the production of a three-layer, tubular or tubular preform.

p0053The head portion 13 of the extrusion head 10 of Figure 1 is designed so that he laminated two melt layers on the coming out of the head portion 11 of molten, while the head portion 13 of the extrusion head 10 is suitable to Figure 1, to laminate a further melt layer on the melt strand, which is supplied to it from the head portion 12th

p0054Each of the head portion 11, 12 and 13, as shown in Figure 5 is designed so that it can be used on its own for the production of tubular or tubular preforms of plasticized material with multilayer wall structure. Thus allows the top portion 11 at an independent application with upstream outlet 14 the yield of a preform with three-layer wall construction.

p0055The head portion 12 is suitable for an independent use for producing a preform having only two-layer wall construction, if it is associated with an outlet nozzle 14.

p0056Finally may be established by the head portion 13 with an independent use and equipped with a discharge nozzle 14, a preform having a single-layer wall construction finished.

p0057By axial series connection or link between the three head sections 11, 12 and 13 to an extrusion head 10 preforms can be created using sechsschichtigem wall construction.

p0058A siebenschichtiger wall structure could be achieved if two head sections 12 would united to an extrusion head 10 having a head portion 11th

p0059By the series connection of a head portion 11 and a head portion 13 to an extrusion head 10, a four-layered wall structure for a preform could be achieved.

p0060So that the individual head portions 11, 12 and 13 in a simple manner appropriately can be combined with each other to receive a different layer structure for the preforms within predetermined limits, the adjacent with each other to be coupled to ends of the head portions are provided with complementary mating engagement elements.

p0061When engaging elements are, for example, molded-in recesses 111 in the rear end and integrally formed projections 112 at the other end of the head portions 11, 12 and 13. These come under 1 then so together in Achsfluchteingriff that the outlet channels 24 and / or through channels 68 and 102 all in succession set head portions 11, 12, 13 functioning properly correspond to each other. The cohesion between the head portions 11, 12 and 13 of an extrusion head 10 is effected via detachable screw 113, as can be seen in Figure 1 of the drawing, for example.

p0062Also, the outlet nozzle 14, as shown in Figures 1 and 5, has a configuration which allows for coupling with each engaging member 112 of the head portions 11, 12 and 13 easily.

p0063From Figures 1 and 5 of the drawing is easy to see that the individual spiral mandrels associated sleeves can be 21, 37 and 48 or 37 and 48 or 85 constructed and installed independently. It is therefore possible that different spiral distributor from each head portion 11, 12, 13 and / or each other thermally separated install and to provide them with independent tempering or combine readily.

p0064This configuration option allows it to then inject plastic materials with very different temperatures of the extruders from the extrusion head 10 to maintain these temperatures even in the distribution of material within the extrusion head 10 and then allow only the layered extrudate temperature compensation.

p0065With relatively little technical effort can be achieved by the measures described above, the production of preforms realize from diverse layers build their walls.

p0066In Figure 6 of the drawings, an extrusion head is in a purely schematic representation shown 10, which each have a head portion 11 and a head portion 12 includes, but between the head portion 12 and the outlet 14 a head portion is still positioned 114, for the only one passageway 115 includes the tubular or tubular melt strand with fünfschichtigem wall construction. This ensures that all successive laminated melt layers have to travel a given, common flow distance before they reach the extrudate formation in the outlet nozzle 14th

p0067In the embodiment of an extrusion head 10 of Figure 6, a head portion 114 with only one passageway 115 between a head portion 11 and a head portion 13 is installed as shown in FIG. 5 It can thus produce a preform which has a four-layer wall construction and wherein the successive in the head portion 11 laminated three wall layers only have to go through a common flow path of predetermined length before the fourth and final melt layer is laminated onto the preform.

p0068The types of head sections 11 to 13 and 114 described above for extrusion heads 10 allow a richly varied wall structure during the extrusion of tubular or tubular preforms of plastic material on the basis of the so-called co-extrusion using in their Druchmesser relatively small and in terms of its length and relative short extrusion heads 10th