Extrusion assemblies

Abstract: An extrusion assembly comprises a feed member (18) rotatable about its own axis in a feed member passage bore (20) in a die subassembly (12). The die subassembly (12) has two opposing die passages (22,23) leading to alternative die openings. Extrusion material from extruder (A) passes through the feed member (18) to a feed opening which can open into either one of the two die passages (22,23) according to the selected orientation of the feed member (18). In other embodiments, a similarly movable feed passage defining member enables selection of extrusion material from one of plural extruders, to go to a specified die passage. The possibility for rapidly changing extrudate path can increase output e.g. when cleaning of the die passages or changing of die plates (29) is needed.

Description: The present invention relates to extrusion assemblies and particularly though not exclusively to techniques for extruding curved or straight extrudate which are a development of the techniques disclosed in our EP-A-347 200. The process of extrusion comprising charging solid extrudable material, such as rubber, to a heat chamber of an extruder is well known in the art. The material is heated in the chamber to a flowable state and forced from the chamber through an opening in a die assembly by a rotatable screw. The extrudate is then removed using a conveyor system. In the past, extruded products having a profile, such as rubber automobile and refrigerator door seals, have been limited to linear extruded configurations. To obtain profile seals having angular configurations, for example, individual lengths of linear extrudate were joined at their respective ends to create corners or bends to form the final seal shape, such as by a separate molding step. The additional process step increased the time and expense of manufacture and created potential operational problems. Specifically, the corner junctions of the final product might be weaker than the component lengths, which could result in potential seal failure points, or the junctions might have deformed or distorted cross-sectional configurations relative to the cross section of the extrudate lengths which are unattractive in appearance, and could cause a reduction in seal efficiency. The discovery of a method and apparatus for continuously manufacturing curved or bent extrusions having undistorted cross-sectional shapes, as set forth in co-pending EP-A-347 200, eliminated the problem of joining extrudate lengths to make curvatures or bends. However, several problems still exist with respect to changing the profile of the extrudate being manufactured. The process of changing the profile of an extruder die assembly, or the extrudate material exiting the die assembly, typically requires shutting down the extruder and extrusion process line. If the die change takes an appreciable amount of time, it may be necessary to purge hot material from the extruder to prevent unwanted crosslinking or degradation reactions in the extrudate material. It may also be necessary for extrudate already manufactured, but not yet completed, to be transported through the remainder of the manufacturing line by a conveyor, or other conventional method, to complete the curing, cooling or crosslinking process. Under these circumstances, restarting the line may require extrudate already manufactured to be fed by hand through the line to form a continuous extrudate. This process is time consuming and may result in considerable extrudate material being wasted. The extruder may also require cleaning to begin extrusion of a different extrudate material. This process may take from 15 minutes to several hours, depending on whether or not the extruder must be purged or the line broken, in addition to any desired profile changes. CH-A-587117 disclosed extrusion apparatus enabling rapid change from one extruder die to another, feeding from a single extruder. The output tube from the extruder forms an axle on which a two-headed die assembly can rotate on a sleeve, so that an inlet conduit of either head can be brought into register with a transverse feed opening of the extruder output tube. The inlet conduit of each head leads radially outwardly and into a respective die block whose die passage then extends to the die opening in a direction transverse to the inlet conduit. Rather similarly, US-A-4826423 describes extrusion apparatus for feeding thermoplastic winding strip (for covering a reinforced plastic tube) in any of three different widths from a single extruder. In one version (Fig. 5) the output tube from the extruder forms both a feed and a rotation axle for an extruder head assembly having three heads, each with a different size of circumferentially-directed die openings. Material is fed radially outwardly from the axial feed tube and then circumferentially from the selected die opening. The aim herein is to provide novel extrusion apparatus adapted for change from one die opening to another, and also adapted for controlling the curvature of extrudate from a given die opening, in an advantageous way. In one aspect the invention provides an extrusion die assembly comprising a die head having plural die passages leading to respective die openings of the die head, and a feed member through which in use extrusion material is supplied to the die head along a longitudinal feed passage thereof, emerging through a transverse feed opening thereof; the feed member being received in a feed member passage of the die head which communicates with the die passages, and the feed member and the die head being relatively movable with respect to one another between respective conditions in each of which the feed opening is presented to a respective one of said die passages to oppose the die opening thereof, and in which for each of said conditions, the feed member and the die head are also controllably relatively movable to vary the distribution, across the die passage, of the extrusion flow path length between the feed opening and the die opening of the die passage, to control a variable degree of bending imparted to extrudate by the die head. In another aspect the invention provides an extrusion assembly comprising an extruder; a die head comprising a block fixed in relation to the extruder and having a bore, with first and second die passages extending divergently away from communication with the bore to respective first and second die openings at different surfaces of the block; a feed member communicating between the extruder and the die passages, the feed member being received in the bore of the die head block and having a feed passage extending longitudinally through it, emerging at a transverse feed opening in axial register with the die passages so as to be rotatable into communication with either one of the die passages by rotation of the feed member in the bore, and means for controllably rotating the feed member. That is, an extrusion assembly comprises a feed member, which defines a part of the extrudate path between extruder and die passage in the assembly, preferably by relative movement in a bore, in such a way that an extruder can be connected thereby to any selected one of plural die passages. It may also be provided that any selected one of plural extruders can be connected to a given die passage. It thereby becomes possible to provide a rapid change assembly for configuring extrudate flow, including an extruder die subassembly which may be rapidly changed to manufacture extrusions having an alternate profile configuration. An extrudate material switch subassembly may also be provided, which may be rapidly changed to supply an alternate material to the die subassembly. The extruder die subassembly may extrude to a predetermined longitudinal and profile configuration, and enable rapid and convenient changes of the die to manufacture an extrusion having a different profile configuration. An extrudate material switch subassembly may also be rapidly and conveniently used to enable the manufacture of an extrusion of a different extrudate material. The extruder die subassembly may have a die head and a feed member which may also be used to generate curved extrusions. The die head includes a feed member passage for engagement by the feed member, and first and second die head passages extending from the feed member passage. First and second die surfaces are also included on the die head. The die surfaces are each associated with a respective die head passage, so that the die head passages are located intermediate the feed member passage and their respective die surfaces. Die plates with openings for producing the desired extrudate profile configuration are secured to the respective die surfaces. It is noted that the die head may include a greater or lesser number of die head passages, each of which may include a die plate with a different extrudate profile configuration. The feed member is supported within the feed member passage of the die head for relative movement with respect to the die head. In one embodiment of the present invention disclosed in this application, the feed member is operatively interconnected with an extrudate source for supplying extrudate material to the die head via a feed passage and a feed opening. In a second embodiment, the feed member may be operatively interconnected with the extrudate switch assembly for receiving alternate extrudate materials. The feed opening nay have a first central axis, and the first and second die head passages have second and third central axes, respectively. The first central axis and second central axis are movable with respect to one another upon movement of the feed opening or first die head passage with respect to the other of the feed opening or first die head passage, respectively. The first central axis and third central axis are also movable with respect to one another upon movement of the feed opening or second die head passage with respect to the other of the feed opening or second die head passage, respectively. Movement of the axes correspondingly configures extrudate exiting one of the die head passages when the feed opening is in communication with the die head passage. During operation of the assembly, the feed opening is in communication with either the first or second die head passages. The relative movement between the feed member and die head enables selective control of the path of extrudate material exiting the die head. As described in EP-A-347 200, using the die assembly may permit selective and variable bending of the extrudate as it exits the die head. The desired longitudinal curvature in the extrudate is obtained by moving the feed opening with respect to the first or second die head passage. As a result of the relative movement, the extrudate flow and the length of the pathways along which the extrudate flows as it exits the die head, are selectively varied to obtain the desired overall curved longitudinal extrudate configuration. When it is desired to manufacture an extrusion with a different profile from the profile formed by the die plate associated with the first die feed passage, the feed member and die head are moved relative to one another so that a different profiled extrusion is produced using the die plate associated with the second die feed passage. Movement of the feed member and die head is such that the feed opening rapidly moves into communication with the second die feed passage. In this position, extrudate material is no longer supplied to the first die feed passage. The first die feed passage may thus be cleaned, and/or the die plate replaced to accommodate another die plate for forming an alternate profile. By providing the rapid change from the first die feed passage to the second die feed passage, which takes approximately one second, the extruder and manufacturing line need not be shut down to change die plates, or to perform regular cleaning of the die head or other maintenance. The extruder need not be turned off, and the old and new extrudate profiles can be quickly rejoined to maintain continuity of the line. In a second embodiment of the rapid change assembly, the extrudate material switch subassembly is included. The switch subassembly includes a housing and a switch member having extrudate supply passages operatively interconnected between an extrudate source and the feed member for supplying extrudate material to the die head of the die subassembly. The housing supports the switch member for relative movement between positions in which the die assembly is supplied with extrudate material from either a first or second extruder. During operation of the rapid change assembly it may be desired to manufacture an extrusion having the same profile, but of a different extrudate material. Use of the switch subassembly enables the supply of extrudate material to the die subassembly to be rapidly changed from one extruder having one type of extrudate material, to a second extruder having an alternate type of extrudate material. The housing and switch member are such that they may be rapidly moved to provide communication between the first extruder and feed member or the second extruder and feed member. When, for example, the first extruder is no longer supplying extrudate material, the extruder may be cleaned, and/or provided with an alternate extrudate material. By providing the rapid change from the first extruder to the second extruder, the extruder and manufacturing line need not be shut down during production to change materials, or to perform regular cleaning or other maintenance. Changing feed material using the switch subassembly is preferably done while the first extruder is operating to supply material to the die head, and the second extruder having the desired replacement material is operating at a steady state. Using this preferred mode of switching minimizes interruption to line operation. Additionally, it is noted that the volume of material between the switch subassembly and the feed opening is preferably as small as possible to minimize mixing between the different extrudate materials. These features, as well as additional advantages of the present invention, will be better understood from the following detailed description and attached drawings setting forth details of embodiments of the invention. Brief Description of Drawings Figure 1 is a perspective view of an extruder die subassembly; Figure 2 is a perspective view of a die head of the extruder die subassembly; Figure 3 shows a bottom plate of the extruder die subassembly; Figure 4 is a side view of a feed member of the extruder die subassembly; Figure 5 is an end view of the feed member of the extruder die subassembly, taken along the plane 5-5 of Figure 4. Figure 6 is a front view of a second embodiment of the extruder die subassembly, for producing a coated extrudate; Figure 7 is a top view of the die head, feed member and die plate of the second embodiment; Figure 8 is a front view of the die plate of the second embodiment of the extruder die subassembly, taken along the plane 8-8 of Figure 7. Figure 9 is a view of a coated extrudate manufactured using the second embodiment of the extruder die subassembly; Figure 10 is a front view of a third embodiment of extruder die subassembly, for dual extrusion; Figure 11 is a cross-sectional view of a die head of the third embodiment of the extruder die subassembly of the rapid change assembly, taken along the plane 11-11 of Figure 10. Figure 12 is a front view of an extruder die subassembly and extrudate switch subassembly; and Figure 13 is a front view of an extruder die subassembly and an alternate embodiment of an extrudate switch subassembly. A rapid change assembly, indicated generally at reference numeral 10, for configuring extrusions, and which may be rapidly changed to manufacture extrusions having different profile configurations, is illustrated in Figures 1, 6 and 10-13. Specifically, Figure 1 illustrates a rapid change assembly having an extruder die subassembly 12 which controls the overall longitudinal configuration and profile of the extrudate. Figures 12-13 additionally illustrate a rapid change assembly having an extruder die subassembly and an extrudate switch subassembly 14 for rapidly changing the type of extrudate material which is supplied to the die subassembly. Where the structural elements are the same in these embodiments, the same reference numerals will be used, but with additional prime designations being used with respect to the second, or additional, embodiments. Turning now to the embodiment of Figure 1, an extruder A is shown in conjunction with the extruder die subassembly 12, which controls the overall longitudinal and profile configuration of the extrusion, by selectively varying the path and curvature of the extrudate. As schematically illustrated in the embodiment, the extruder die subassembly is mounted adjacent the extruder A which is a suitable and conventional device not disclosed in detail. In Figure 1, the extruder die subassembly includes a die head 16 and a cylindrical feed member 18. The die head 16 is illustrated in Figure 2, and comprises a rectangular metal member having a feed member passage 20 comprising a cylindrical bore, for supporting the feed member 18. The die head additionally includes first and second die head passages 22, 23 extending from the feed member passage 20. Each of the die head passages includes a central axis 22A, 23A, respectively. The sides 24 of the die head passages diverge from the feed member passage toward an associated die surface 26 on the die head. The die surfaces 26 are each associated with a respective die head passage, so that each die head passage is located intermediate the feed member passage and its associated die surface. A bottom plate 27 having an alignment opening 28 therein for aligning and centering an end post 19 of the feed member 18 in engagement with the die head, is further illustrated in Figure 3. The bottom plate is secured to the die head 16 using conventional fasteners (not illustrated). When secured to the die head as shown in Figure 1, the bottom plate 27 forms a side 25 of each of the die head passages. A die plate 29 is secured to the die head 16 covering each of the die feed passages, as shown in phantom in Figure 1. The die plate includes an opening 30 configured for producing any desired extrudate profile configuration. It is understood that the die head illustrated could be configured in a variety of geometrical shapes in order to include additional feed member passages and associated die surfaces, as may be desired. Additionally, each die surface 26 may include a die plate 29 having a different shaped opening 30 for manufacturing extrusions of a desired profile configuration. The feed member 18 is supported within the feed member passage 20 of the die head 16 for relative movement with respect to the die head. In the embodiment of the invention illustrated in Figure 1, the cylindrical feed member 18 is rotatable with respect to the die head 16 within the feed member passage 20. The feed member, as further illustrated in Figures 4 and 5, includes a feed passage 32 comprising a cylindrical bore, and having a feed passage axis 32A. A feed opening 34 is also included having an axis 34A, which, in the embodiment illustrated in Figure 6, is perpendicular to the feed passage axis 32A. In the embodiment of the invention shown in Figures 1 and 2, the feed member 18 is operatively interconnected with the extruder A. During the manufacture of extrusions using the rapid change assembly, extrudate material flows from the extruder A via the feed passage 32 and feed opening 34 into either the first or second die feed passage 22, 23. Since the feed member is rotatable within the die head 16, either the first or second die head passage may be selected, depending upon which passage is adjacent the die plate for forming the desired extrusion profile. The desired feed passage is selected by either manually rotating a handle member 36 secured to the feed member 18, as shown in Figures 1 and 5, so that the feed opening 34 and desired die feed passage are in communication. Alternatively, the feed member 18 may be coupled to computer controlled hydraulic, pneumatic or other actuators (not illustrated). The feed member 18 may be moved rapidly within the die head 16, so that, for example, in about 1 second the feed opening 34 may be changed from communication with the first die feed passage 22 into communication with the second die feed passage 23. Once the feed opening 34 is in communication with the second die feed passage 23, extrudate material is no longer supplied to the first die feed passage 22, and that passage may then be cleaned, or the die plate 29 may be replaced with another die plate for forming yet another desired extrusion profile. Because the assembly is capable of changing from one profile extrusion to another very rapidly, the assembly described eliminates the need to shut down the extruder and manufacturing line for die changes or maintenance. In addition to using the movement of the feed member 18 between die feed passages to make rapid extrusion profile changes, selective movement of the feed opening 34 with respect to the individual die feed passages, also controls the path and curvature of the extrudate. Movement of the feed member 18 to obtain angles or curves in the desired predetermined overall configuration of the extrudate is accomplished by varying the pathway along which the extrudate travels to the die plate opening. Varying the length of the pathway causes the extrudate to bend as it exits the rapid change assembly 10. Movement between the feed opening and die feed passage, also results in relative movement between the feed opening axis 34A and the die head passage axis 22A or 23A. Movement of the axes with respect to one another correspondingly configures extrudate exiting the die head passage. The relative movement for bending the extrudate to the desired overall predetermined configuration is provided either by manual movement of the handle member by a skilled operator, or computer controlled using interconnected actuators, as described above. An alternate embodiment of the extruder die subassembly 12' for manufacturing extrusions having a coating of a different extrudate material, is illustrated in Figure 6. In the alternate coating embodiment, the feed member 18' is in communication with one extruder A', is supported within the die head 16', and extends through the die head into engagment with a second extruder B. The feed member is thus operatively interconnected at both of its ends with different extruders, each supplying extrudate material. The feed member (illustrated in Figure 7) includes a feed passage 32' and feed opening 34' in communication with an extruder A'. Additionally, a second feed passage 38 and second feed opening 40 are also provided. The second feed passage 38 comprises a cylindrical bore, and has a second feed passage axis 38A. The second feed opening 39 also includes an axis 39A, which, in the embodiment illustrated in Figure 7 is perpendicular to the second feed passage axis 38A. In the illustrated coating die subassembly embodiment, the feed passage axis 32A', and the second feed passage axis 38A are parallel and extend axially of the feed member 18' in opposite directions. The feed opening axis 34A' and second feed opening axis 39A are also parallel as shown in Figure 7. In the configuration of the feed member illustrated in Figure 7 the feed opening 34' and second feed opening 39 are spaced from one another to provide extrudate material to the first die head passage 22' and a third die head passage 40, respectively. In this alternate embodiment, the first and second die head passages 22', 23' comprise cylindrical bores extending outwardly from the feed passage 20' toward the die surface 26'. Each of the die head passages includes a central axis 22A', 23A. A fourth die head passage 41 is also provided in the die head opposite the third die head passage 40, and includes a central axis 41A. The die plate 29' provided in the coating embodiment is illustrated in Figures 7 and 8. The die plate is provided in two parts 29', 29A', with the first part 29' secured to the die surface 26' of the die head 16'. The die plate is secured to the die head by conventional means covering the first and third die head passages 34', 40. The first part of the die plate includes an opening 30' configured for producing the desired extrudate profile, and a bore 80 for receiving the coating extrudate to be provided on the extrusion being manufactured. As shown in Figures 7 and 8, the bore 80 has a cut-away portion 81 providing communication between the bore 80 and the die opening 30'. The second part 29A' of the die plate is secured to the first part of the die plate 29', also by conventional means, and includes a die opening 30A' conforming to the die opening 30'. With this configuration, the die openings in both the first and second parts of the die plate are aligned once the plates are secured together. Using this embodiment of the die plate, extrudate material from extruder B exiting from the third die head passage 40 is coated on the surface of one leg with extrudate material from extruder A' exiting from the first die head passage 22'. Upon exiting the die head, the coated extrusion R has a configuration of the type shown in Figure 9, having extrudate F from extruder A' coated on one leg thereof. The die head 16' in the coating embodiment of Figure 6 is provided with first and second die head passages 22', 23', and third and fourth die head passages 40, 41. As with the embodiments of Figures 1-5, the feed member 18' of the coating embodiment may thus be rapidly changed from a position wherein the feed openings 34', 39 are in communication with the first and third die head passages 22', 40, to a position wherein the feed openings are in communication with the second and fourth die head passages 23', 41 to manufacture a coated extrusion having a different desired profile. This is accomplished in the manner previously discussed with respect to the rapid change assembly of Figure 1. The feed member 18' is rotated within the die head using either a handle member 36' as in Figure 6, or a computer coupled with an actuating device (not illustrated), as previously described. A second alternate embodiment of the extruder die subassembly for manufacturing extrusions having a dual extrusion profile of different extrudate materials, is illustrated generally in Figures 10 and 11 by reference number 12''. In the alternate dual extrusion embodiment, the feed member 18'' is supported within the die head 16'', and a second feed member 42 is supported within a second die head 44. Alternatively, a single elongated feed member (not illustrated) may be used in lieu of two opposing feed members. In the event a single feed member is substituted for the first and second feed members 18'', 42, the feed member extends through an aperture in the bottom plate 27'', and is rotated using a single handle member 36'', or a single coupling to a computer controlling and actuating device, similar to those illustrated in Figure 11, and previously described. In the single feed member embodiment, the overall longitudinal configuration of both extrudate material portions of the extrusion is the same, since the rotation of both feed openings is simultaneous. In the two feed member embodiment illustrated in Figure 10, the second die head 44 includes a feed member passage 45 comprising a cylindrical bore for supporting the second feed member 42. The die head additionally includes first and second die head passages 50, 52, which extend from the feed member passage 45. As shown in Figures 10 and 11, the bottom plate 27'' is engaged intermediate the die head 18'' and second die head 44. When two feed members are used, the bottom plate includes alignment openings (not illustrated) on each surface engaged with a die head. The alignment openings in the bottom plate are preferably engaged with the first and second feed members for centering the feed members in proper operating position. When secured between the die heads, the bottom plate 27'' forms a side 25'' of the die head passages 22'', 23'' on the one die head 18'', and a side 46 of the die head passages 50, 52 on the second die head 44. The feed members 18'', 42, include feed passages 32'', 48 and feed openings 34'', 47, each of which are in communication with a respective extruder A'', C. When extruding material through the first die head passages 22'', 50, the feed openings 34'', 48 are in communication with the die head passage 22'', 50, as illustrated in Figure 10. When it is desired to extrude material through the second die head passages 23'', 52, for example, to obtain another desired extrusion profile using another die plate, the feed members are rapidly, and simultaneously, moved within their respective die heads. Once the feed openings 34'', 47 of the feed members 18'', 42 are in communication with the second die head passages 23'', 52, extrudate material is no longer supplied to the first die head passages, and the passages or their respective die plates, may be cleaned or replaced as set forth above, while continuing to operate the extruders and manufacturing line. A tapered divider plate 82 is also provided on the bottom plate 27'', so that extrudate materials exiting the die head passages 22'', 50, are in communication with one another upon entering the die opening 30''. Additionally, in the preferred embodiment of the die heads 16'', 44, and as illustrated in Figure 11, the diameter of the feed opening 48, generally referenced at arc 99, is larger than arc, generally referenced at 100, defined by the die head between the first and second die head passages 50, 52. With this configuration the danger of obstructing the flow of extrudate, or of dead-ending extrudate within the die head and thereby building up pressure within the die head, is substantially reduced. Such obstruction is reduced when the feed opening arc 99 is larger than the arc 100 between the die head passages, since the feed opening cannot be completely blocked, even if it is incorrectly moved to a position between the die head passages. To further avoid incorrect positioning of the feed member, mechanical stops (not illustrated) external to the die head may be used to ensure that the feed opening is consistently rotated to a properly aligned position with respect to the desired die head passage. Such mechanical stops are also provided to properly position the feed member to obtain the desired predetermined longitudinal extrudate configuration. Operation of the feed members 18'', 42 with respect to rapid movement for obtaining angles or curves in the desired predetermined overall configuration, is obtained using the handle members 36'' shown in Figure 10, or computer controlled hydraulic, pneumatic or other actuators, as schematically illustrated and generally referenced at 37 in Figure 11. Such operation is substantially similar to the operations described above, and thus is not further described in detail. However, it is noted that the use of two feed members in the dual extrusion profile embodiment of the extruder die subassembly enables the operator to simultaneously, or individually, vary the length of the pathway of each portion of the extrudate R''. By varying the pathways of the different material portions of the extrudate individually, a single extrusion profile is provided wherein the portions of the extrudate manufactured of different extrudate materials may vary with respect to one another in configuration. In a second embodiment of the invention illustrated in Figures 12-13, an extruder die subassembly, generally referenced at 12''', of the type previously discussed with respect to Figure 1, is operatively interconnected with the extrudate switch subassembly, generally referenced at 14. The extrudate switch subassembly 14 is interconnected with two extruders D or E, such that extrudate material supplied to the extruder die subassembly 12''', may be rapidly changed to a different desired extrudate material. As shown in Figure 12, the extrudate switch subassembly 14 includes a housing 54 and a switch member 56. The housing 54 is interconnected with a feed member 18''' of the extruder die subassembly 12''', and includes a cylindrical bore 58 for supporting the switch member. The bore 58 is centrally positioned and extends longitudinally within the housing of the bore. The housing additionally includes first and second supply passages 60, 62, each of which is in communication with a respective extruder D or E. An extruder passage 64 is also provided in the housing, and is in communication with the feed passage 32''' of the feed member 18''' of the extruder die subassembly. Each of the first and second supply passages and extruder passage comprise cylindrical bores in communication with the bore 58 of the housing and extending therefrom. A dump port 66 is additionally provided in the housing, which also comprises a cylindrical bore in communication with the bore 58 of the housing and extending therefrom. Using the dump port, extrudate material from either of the extruders D or E may be vented from the housing as desired. In the embodiments of both Figures 12 and 13, the switch member 56 comprises a cylindrical member engaged within the bore 58. During operational engagement of the switch member within the housing, the switch member is rotatable between positions, so that the feed passage 32''' of the feed member 18''' may be selectively positioned in communication with either of the extruders D or E, for supplying different extrudate materials to the extruder die subassembly 12'''. The switch member is moved between positions by either manually moving a handle member 70, as in Figure 12, which is secured to the switch member 56. Alternatively, the switch member may be coupled to computer controlled hydraulic, pneumatic or other actuators as previously discussed, and schematically illustrated and generally referenced at 72 in Figure 13. The switch member 56 includes first and second switch passages 68, 69 extending through the switch member. As illustrated, the switch passages are positioned parallel to one another within the switch member. Such passages ensure that each extruder D or E is in communication with a passage to avoid the pumping of material intermediate the switch member and housing which may interfere with operation. When it is desired to supply extrudate from the extruder E to the feed member 18''' via a housing supply passage 62, first switch passage 68 to the feed passage 32''' the switch member 56 is moved to the position illustrated in Figure 12. When it is desired to change extrudate materials, and provide material to the die head from extruder D, the switch subassembly is moved to its second position, illustrated in Figure 13. In this position, extrudate is supplied from said second extruder through a housing supply passage 60, second switch passage 69 to the feed passage 32'''. The dump port 66 is provided for removing undesired extrudate material from the extruder switch assembly. By providing a dump port, neither of the extruders D, E are required to be shut down during operation of the switch subassembly. The extruder currently supplying extrudate material continues to operate until after the switch is complete, and the extruder supplying the new material is allowed to operate at a steady state prior to the switch. The extrudate material not being supplied to the feed member 32''' exits the housing 54 via the dump port 66 to minimize any interference from excess extrudate material.

Claims: An extrusion die assembly comprising a die head (16,44) having plural die passages (22,23;40,41;50,52) leading to respective die openings (30) of the die head, and a feed member (18,42) through which in use extrusion material is supplied to the die head along a longitudinal feed passage (32,38,48) thereof, emerging through a transverse feed opening (34,39,47) thereof; the feed member (18,42) being received in a feed member passage (20,45) of the die head (16,44) which communicates with the die passages, and the feed member (18,42) and the die head (16,44) being relatively movable with respect to one another between respective conditions in each of which the feed opening (34,39,47) is presented to a respective one of said die passages to oppose the die opening (30) thereof, and in which for each of said conditions, the feed member and the die head are also controllably relatively movable to vary the distribution, across the die passage, of the extrusion flow path length between the feed opening (34,39,47) and the die opening (30) of the die passage, to control a variable degree of bending imparted to extrudate by the die head. A die assembly according to claim 1 in which the feed member passage (20,45) is a bore of the die head, and movement between said conditions is by relative rotation between the feed member and the bore, about the axis thereof. A die assembly according to claim 1 or claim 2 in which the die openings face in different directions. A die assembly according to any one of the preceding claims in which the die passages (22,23;40,41;50,52) diverge outwardly from the feed member passage (20,45) to their die openings. A die assembly according to any one of the preceding claims in which the die head (16,44) is a single block and the feed member passage (20,45) and die passages are defined within that block. A die assembly according to any one of the preceding claims in which plural said die openings open through separate respective plane surfaces of the die head (16,44). A die assembly according to any one of the preceding claims having two said die passages (22,23) in the die head (16,44). A die assembly according to any one of the preceding claims having two said feed passages (32',48) with respective feed openings (34',39;34'',47) for feeding from separate respective supplies of extrusion material, each said feed passage serving a respective plurality of die passages. A die assembly according to claim 8 in which the two feed passages are in axial alignment with one another, and their feed openings are axially spaced from one another. A die assembly according to claim 8 or claim 9 in which the feed passages (32',48) and their feed openings (34',39;34'',47) are in separate feed members (18'',42) whose rotational relative movements are independently controllable. A die assembly according to claim 8 or claim 9 in which both feed passages (32',38') are provided in a single feed member (18') such that their relative movements occur in unison. A die assembly according to any one of claims 8 to 11 in which there are two die heads (16'',44) juxtaposed, each having a respective said feed member passage (20,45), associated feed passage (32'',48) and feed opening (34'',47), and plural die passages. A die assembly according to claim 12 in which the feed member passages (32'',48) of the juxtaposed die heads, (16'',44) are axially aligned. A die assembly according to any one of claims 8 to 13 in which respective die passages (22',23') served by one of the feed passages (32') are associated with respective die passages (40,41) served by the other feed passage (38), the associated die passages (22',40;23',41) having their openings at the same face of the die head (16') for simultaneous extrusion of materials from both of them into a single extrudate. A die assembly according to claim 14 in which the associated die passages (22',40;23',41) emerge through a common die plate (29). A die assembly according to any one of the preceding claims, further comprising an extruder switch assembly (14) for connecting a said feed passage (32''') to a selected one of plural extruders (D,E), said extruder switch assembly (14) comprising a respective supply passage (60,62) from each said extruder (D,E), an output to the feed passage (32''') and a switch member (56) which is movable to put the feed passage in communication with a selected one of said supply passages (60,62). A die assembly according to claim 16 in which there are two supply passages (60,62) and the switch member (56) is a cylindrical member having two internal passages (68,69) extending through it, one of the internal passages connecting a first said supply passage to the feed passage (32''') in a first position of the switch member (56), and the other internal passage connecting the other said supply passage to the feed passage (32''') in a second position of the switch member (56). A die assembly according to claim 16 or claim 17 in which the switch member (56) can connect a selected one of said extruders (D,E) to a discharge vent (66). A die assembly according to any one of the preceding claims in which the relative movement between the feed member and die head is computer-controlled. An extrusion assembly comprising at least one extruder (A,B,C,D,E) and at least one extrusion die assembly according to any one of claims 1 to 19, with the output of the extruder connected to a said feed passage of the die assembly. An extrusion assembly comprising an extruder (A,B,C,D,E); a die head (16,44) comprising a block fixed in relation to the extruder and having a bore (20,45), with first and second die passages (22,23) extending divergently away from communication with the bore (20,45) to respective first and second die openings at different surfaces of the block; a feed member (18,42) communicating between the extruder and the die passages, the feed member being received in the bore (20,45) of the die head block and having a feed passage (32,38,48) extending longitudinally through it, emerging at a transverse feed opening (34,39,47) in axial register with the die passages (22,23) so as to be rotatable into communication with either one of the die passages by rotation of the feed member in the bore (20,45), and means for controllably rotating the feed member (18,42).

Inventors: MILLER WILLIAM H, STEVENSON JAMES F, MILLER, WILLIAM H., STEVENSON, JAMES F.
Applicants: GENCORP INC, GENCORP INC.
Application year: 1990
Main classification: B29C47
IPC codes: B29C47