GB2378411A

GB2378411A - Calibration plate for a shaping device of an extrusion system

Info

Publication number: GB2378411A
Application number: GB0213155A
Authority: GB
Inventors: Reinhold Kossl
Original assignee: Greiner Extrusionstechnik GmbH
Current assignee: Greiner Extrusionstechnik GmbH
Priority date: 2001-06-08
Filing date: 2002-06-07
Publication date: 2003-02-12
Anticipated expiration: 2022-06-07
Also published as: ATA8902001A; GB2378411B; AT411162B; DE10222922B4; DE10222922A1; DE20111198U1; GB0213155D0

Abstract

The invention relates to a calibration plate (17) for a shaping device with end faces (30, 31) spaced at a distance apart from one another, extending between which is at least one aperture (24) with shaping surfaces (25) through which an extruded article is fed. At least one recessed receiving orifice (27) is provided in the calibration plate (17), in which a wear-resistant insert (28) with a retaining part (33) is inserted. Delimiting surfaces (29) of the receiving orifice (27) and external surfaces (35) of the retaining part (33) form a guide arrangement (36) at least in certain regions. Co-operating limiting stops (37, 38) with stop surfaces (39, 40) for the guide arrangement (36) are provided around a major part of a peripheral region, both in the region of the receiving orifice (27) and on the retaining part (33) and are provided with stop surfaces (39, 40) for the guide arrangement (36).

Description

: 237841 1

CALIBRATION PLATE FOR A SHAPING DEVICE OF AN

EXTRUSION SYSTEM

The invention relates to a calibration plate for a shaping device of an extrusion system and, more specifically, to such a plate having an insert retained therein.

Short gauges for a cooling and calibrating device are known from patent 5 specifications DE 198 06 202 C1 or EP O 936 053 A1 and comprise a calibration

plate and at least one orifice with a profiled cross section provided therein and at least one calibration body, which projects partially into the orifice with a profiled cross section. The article to be calibrated, in particular a hollow section of plastics material, is drawn through the orifice with the profiled cross section. The to orifice with the profiled cross section disposed in the calibration plate is provided with at least one locking recess, in which the calibration body with its lock element can be inserted. The lock element in turn comprises a foot and a calibration body attached to it, an orifice being provided in the lock foot to receive a pin. Another slot recess is also provided in the lock body. In order for the lock t5 body to be retained, it is must be placed in the lock recess of the calibration plate and secured by means of a conical locking pin, which is inserted in the pin housing recess on the calibration plate. The disadvantage of this system is that the individual parts have to be manufactured to a high degree of accuracy to ensure that the bearing is fixed correctly on the calibration plate and there is no JO guarantee that it will not inadvertently work lose in all applications.

Another calibrating plate for the tank of an extrusion tool is known from patent specifications AT 003 321 U1 and DE 299 06 109 U1, in which at least one

orifice is provided, the shape of which substantially corresponds to the profile of 25 the extruded material, in order to guide the strand of extruded material and maintain its shape as the strand is being fed through. To this end, wear-resistant inserts are provided on the circumference of the orifice in the calibration plate at points along which the profiled strand is displaced and these are retained in the

- calibration plate by means of a press-fit seating, bonded or soldered joints or by screw connections. The disadvantage of this arrangement is that a considerable amount of effort is needed to fix the individual inserts in the calibration die and they have to be replaced with new parts when they become worn, which is also s labour-intensive.

A calibration plate made up of a plurality of individual parts is also known from patent specification US 5,626,807 A, in which individual parts of the calibration

die, in particular those used to impart groove-shaped sections to the plastics to member, are retained and secured between the individual plate segments.

The underlying objective of the present invention is to propose a system of holding an insert in a calibration die reliably and accurately positioned, which is simple and inexpensive to manufacture and can be rapidly replaced.

According to the present invention, there is provided a calibration plate for a shaping device of an extrusion system, said plate comprising end faces spaced at a distance apart from one another in the extrusion direction, and at least one aperture extending between said end faces and having shaping surfaces so through which an extruded article is fed, the shaping surfaces delimiting an external profiled cross section of the article to be fed through, at least in certain regions, and being provided with at least one receiving orifice recessed into the calibration plate and extending from the shaping surface towards the aperture, said at least one receiving orifice having delimiting surfaces extending between :5 the end faces, and at least one wear-resistant insert with a retaining part inserted in the receiving orifice, at least certain regions of the delimiting surfaces and external surface of said retaining part forming a guide arrangement, wherein co-

operating limiting stops with stop surfaces for the guide arrangement are provided around a major part of a peripheral region both in the region of the So receiving orifice and on the retaining part.

t -A A surprising advantage achieved by the present invention is that both the insert, in particular the retaining part thereof, and the receiving orifice co-operating with the retaining part are delimited respectively by enclosing surfaces which are preferably disposed running perpendicular to the end faces and parallel with the 5 extrusion direction, which are simple and inexpensive to produce. An exact guiding system for the insert in the calibration die is obtained at the same time, which ensures that the insert is exactly aligned relative to the calibration die and relative to the article to be drawn through it when in its inserted position.

Restricting stops are disposed along a greater part of the circumferential region, to both in the region of the enclosing orifice and on the retaining part, and co-

operate with stop surfaces for the guide arrangement to restrict the displacement path, whilst additionally providing extra support, which in turn fulfils a force transmission function, whereby force applied by the object abutting with the insert is transmitted to the calibration die. The co-operating abutment surfaces are easy 15 to manufacture and provide an adequate transmission of force.

Another embodiment defined in claim 2 is advantageous because the almost right-angled alignment of the abutment surfaces to the arrangement guiding displacement of the insert means that the position of the insert relative to the to calibration die is Redefined exactly.

Also of advantage is an embodiment of the type defined in claim 3, since, depending on the chosen angle of inclination of the co-operating stop surfaces, the insert is easily released from its operating position in the calibration die, but 25 for a self-locking action.

With the embodiment defined in claim 4, the complementary conical design of the limiting surfaces and the external surfaces of the restricting stop enable the insert to be exactly positioned relative to the calibration die on the one hand, and so obviate the need for additional restricting stops on the other.

r Claim 5 defines another design variant which produces an exact abutment

position and a sufficient and reliable transmission of force between the insert and the calibration die.

5 The advantage of another embodiment defined in claim 6 is that because the manufacturing complexity of the design used for the enclosing orifice can be kept to a minimum and the insert used is made from sintered metal, the restricting stop is technically simple and inexpensive to produce.

to The advantage of the embodiment defined in claim 7 is that the wearresistant insert is strong enough in this region to be able to transmit the forces transmitted from the object to the insert on to the calibration die.

With the embodiment defined in claim 8, the restricting stops can be made to a 15 design that is simple and inexpensive to produce, both in the region of the receiving orifice and in the region of the insert.

The embodiment defined in claim 9 provides support for the article transversely to the extrusion direction in addition to the support afforded in the region of the ho shaping surface of the aperture, as a result of which the profile geometry of the object is correctly aligned.

The design defined in claim 10 is of advantage because supporting forces acting on the insert, in particular on the guide part, can be reliably transmitted in the 25 region of the gap, transversely to the extrusion direction.

The design described in claim 11 provides an inexpensive means of producing the orifice.

The embodiment defined in claim 12 is advantageous because support can also be provided for a force acting from the receiving orifice in the direction of the aperture and hence a tilting moment on the calibration die.

s By virtue of an advantageous embodiment as defined in claim 13, an exact parallel guiding action is provided, which means that the insert is accurately positioned transversely to the extrusion direction.

Claim 14 defines another advantageous embodiment whereby supporting forces to of the guide part can also be transmitted to the calibration die to the shaping surfaces in a vertical direction.

In accordance with claim 15, force is transmitted uniformly from the insert to the calibration die.

The embodiment defined in claim 16 offers an additional possibility of providing support for the insert to prevent it from being lifted out of the receiving orifice in the direction of the aperture.

so Another possible embodiment is that defined in claim 17, which makes replacement easy and as a result ensures that the insert can be positioned in the receiving orifice accurately on a reproducible basis.

The embodiment defined in claim 18 offers an additional positive fit arrangement 25 during the insertion process until the insert is finally positioned relative to the receiving orifice.

Also of advantage is an embodiment as defined in claim 19 or 20, since positioning accuracy and the level or degree of supporting force to be transmitted JO can be easily set by choosing an appropriate number or ribs.

Claims 21 to 23 define embodiments offering advantages, because the farther the displacement during insertion, the more the material of the calibration die deforms, causing the ribs to make impressions in the material of the calibration die, thereby providing additional bearing surfaces to support and fix the insert 5 relative to the calibration die.

Also advantageous is another embodiment defined in claim 24 or 25, because during the insertion process, a supporting force or bearing force acting on the delimiting surface of the receiving orifice is applied by the insert to the calibration to die.

Another embodiment defined in claim 26 is advantageous because during the deformation process, forced material of the calibration die can be pushed into the region of the recess of the insert, thereby preventing the insertion process from 15 being terminated prematurely. The supporting surfaces designed to abut with the rib surfaces is also made larger at the same time.

With the embodiment defined in claim 27, tolerances in the region of the gap between the guide part and the calibration die can be compensated.

By virtue of another embodiment defined in claim 28, the rib surfaces co-

operating with the recesses provided in the receiving orifice form the restricting stop, obviating the need for additional shoulders or projections.

as The advantage of the embodiment defined in claim 29 is that an exact guiding action can be provided between the retaining part or insert and the calibration die. The embodiment defined in claim 30 makes the insert easy to manipulate and so replace.

Also of advantage is an embodiment of the type defined in claims 31 to 33, since the insert is prevented from sitting proud of one of the two end faces of the calibration die and when the individual calibration dies are placed one on top of the other or stacked, the insert is prevented from working loose on the one hand 5 and the surface of the end faces is protected from damage on the other.

The advantage of the embodiment defined in claim 34 is that it is possible to work with certain tolerances in the design of the insert and the receiving orifice in the calibration die because the plastic deformation of the fixing seat, and hence to the positive fit arrangement if one is provided, is guaranteed to remain in place whatever the circumstances.

Finally, another possible embodiment is that described in claim 35, offering a simple possibility of aligning both the insert and the receiving orifice of the Is calibration die exactly and providing an easy manufacturing option.

The invention will be described in more detail below with reference to the embodiments illustrated in the drawings as examples.

20 Of the drawings: Fig. 1 is a highly simplified, schematic diagram of an extrusion plant with a calibration die as proposed by the invention in the region of the shaping device, seen in a side view; Fig. 2 is an enlarged, simplified diagram giving a perspective view of one possible embodiment of the calibration die with inserts; Fig. 3 is an enlarged, schematic, simplified diagram, in partial section, depicting so the insert and the calibration die prior to assembly, seen in a side view;

Fig. 4 depicts a view of the insert in the direction of arrow IV indicated in Fig. 3; Fig. 5 illustrates a view of the receiving orifice in the calibration die in the direction of arrow V of Fig. 3; Fig. 6 is a simplified, schematic diagram illustrating another embodiment of the insert, viewed in the direction of arrow Vl in Fig. 7; Fig. 7 is a side view of the insert illustrated in Fig. 6; Fig. 8 illustrates the associated receiving orifice in the calibration die, viewed in the direction of arrow Vlil in Fig. 9; Fig. 9 is a side view of the calibration die, viewed in section along the lines IX-IX 15 of Fig. 8; Fig. 10 is another embodiment of the insert, viewed in the direction of arrow X in Fig. 11; to Fig. 11 is a side view of the insert illustrated in Fig. 10; Fig. 12 shows the matching receiving orifice for the insert illustrated in Figs. 10 and 11 viewed in the direction of arrow Xll in Fig. 13; 25 Fig. 13 is a side view in section along the lines Xl11-XIII in Fig. 12 of the receiving orifice in the calibration die; Fig. 14 is another embodiment of an insert, viewed in the direction of arrow XIV in Fig. 15; Fig. 15 is a side view of the insert illustrated in Fig. 14;

Fig. 16 is another embodiment of an insert, viewed in the direction of arrow XVI in Fig. 17; 5 Fig. 17 is a side view of the insert illustrated in Fig. 16; Fig. 18 is a simplified diagram giving a plan view of another embodiment of an insert; to Fig. 19 is a side view of the insert illustrated in Fig. 18; Fig. 20 is a view in partial section of the insert illustrated in Figs. 18 and 19, inserted in the receiving orifice in the calibration die; is Fig. 21 is a simplified, schematic diagram showing an end-on view of a part region of the calibration die with an insert and a part of the article with different designs of the guide part.

Firstly, it should be pointed out that the same parts described in the different JO embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be

transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc.. relate to the drawing

25 specifically being described and can be transposed in terms of meaning to a new position when another position is being described. Individual features or combinations of features from the different embodiments illustrated and described may also be construed as independent inventive solutions or solutions proposed by the invention in their own right.

Fig. 1 illustrates an extrusion system 1, consisting of an extruder 2, a shaping device 3 arranged downstream thereof and a crawler off-take 4 for an extruded article 5. The purpose of the crawler off-take 4 is to carry the article 5, which might be a section, in particular a hollow section of plastics for building windows 5 and/or doors, in the extrusion direction 6 out from the extruder 2 into the overall shaping device 3. In the embodiment illustrated as an example here, the shaping device 3 consists of an extrusion die 7 co-operating with the extruder 2, a calibrating device 8 consisting of at least one but preferably a plurality of calibration dies 9 to 13 and at least one but preferably a plurality of vacuum to tanks 14 to 16, in which a plurality of calibration plates 17 are arranged. Some of the individual calibration plates 17 may be designed as supporting plates, however, providing nothing more than a supporting function.

Located in the region of the extruder 2 is a container 18, which is supplied with a material, such as a mixture or granulate, for forming a plastics material, which is fed to the extrusion die 7 in the extruder 2 by means of at least one screw conveyor. The extruder 2 additionally has a plasticizing unit, by means of which, and by means of optionally provided heating devices, the material is heated and plasticized as the material is fed through it by the screw conveyor depending on 20 its intrinsic properties, subjected to pressure and, optionally, additionally applied heat, and conveyed in the direction of the extrusion die 7. Before entering the extrusion die 7, the mass flow of plasticized material is fed to transition zones until the section assumes the desired cross section.

25 The extrusion die, the plasticizing unit and the container 18 are supported or retained on a machine bed 19, the machine bed 19 being placed on a flat standing surface 20 such as a flat factory floor.

In this embodiment, the entire calibration device 8 is disposed or retained on a so calibrating table 21, the calibrating table 21 being supported by means of rollers 22 on a track 23 secured to the standing surface 20. The purpose of mounting

the calibrating table 21 on the tracks 23 by means of rollers 22 is to allow the entire calibrating table 21 to be moved together with the mechanisms and devices arranged on it in the extrusion direction 6 - as indicated by the arrow -

from and to the extrusion die 7. In order to make this displacement easier and s more accurate, the calibrating table 21 is provided with a drive, not illustrated in detail, which enables a selective and controlled longitudinal displacement of the calibrating table 21 towards the extruder 2 or away from the extruder 2. Any solutions and units known from the prior art may be used for the drive itself and

to control this driving motion.

The calibration dies 9 to 13 of the calibration device 8 are supported on a mounting plate and designed to operate the calibration process under vacuum, the extruded article 5 being calibrated within the individual shaping and or calibration dies 9 to 13. Vacuum slits, cooling sections and flow passages and 15 cooling bores, along with connectors and a supply for them, may also be provided in a manner known from the prior art.

The calibration process may be a combination of wet and dry calibration, for example, or may be operated as a totally dry calibration process. Furthermore, 20 steps may also be taken to prevent penetration of any ambient air at least between the extrusion die 7 and the first calibration die 9 and/or at least between the first calibration die 9 and other calibration dies 10 to 13. Clearly, however, it would also be possible to allow the ingress of ambient air to the article 5, at least in certain regions between the individual calibration dies 9 to 13 or to provide 25 water baths.

The vacuum tank 14 to 16 has at least one cooling chamber for the article 5 as it emerges from the calibration dies 9 to 13, provided in the form of a schematically indicated housing, divided into regions disposed immediately one after the other So by means of calibrating plates 17 in the interior, illustrated on a very simplified

basis. Another option, however, would be to reduce the pressure in the interior of the cooling chamber to a level below atmospheric pressure.

On leaving the extrusion die 7, the article 5 is of a shape in cross section which is s determined by the latter, and is sufficiently calibrated and/or cooled in the adjoining calibration dies 9 to 13, so that the surface and peripheral regions of the viscid, plastic article 5 are cooled to the degree that its external shape is stable and duly formed to the requisite dimensions. Adjoining the calibration dies 9 to 13, the article 5 is passed through the vacuum tanks 14 to 16 to impart JO additional cooling and, optionally, calibration and support, thereby dispersing any residual heat which might still be present.

In order to operate the extrusion system 1, in particular the mechanisms and devices disposed and retained on the calibrating table 21, the latter are 15 connected to a supply system, not illustrated in detail, by means of which a whole variety of units can be supplied with a liquid coolant, electric power, compressed air and a vacuum. The most varied of energy conveyors may be selected and.

used, depending on requirements.

Jo In order to feed the article 5 through the individual calibrating plates 17, the latter have at least one aperture 24, individual shaping surfaces 25 of the aperture 24 delimiting or bounding an external profiled cross section 26 of the article 5 to be fed through, at least in certain regions. As explained above, as the article 5 is fed through the individual calibration dies 9 to 13, its external walls are cooled 25 and the softened plastics material solidified to the degree that the external profiled sections of the hollow section already have a certain intrinsic rigidity or solidity. In order to be able to disperse completely the residual heat of the article 5 still present in the section interior, particularly in the region of the hollow compartments and the lands arranged therein, the vacuum tanks 14 to 16 in the JO embodiment illustrated here have calibration plates 17 disposed in them. During this additional cooling and solidification process, because of the different rates at

which heat is dispersed along the cross section, internal tensions in the region of the profiled cross section are relieved and, as a result, the article 5 must be guided at predetermined points of its cross section in such a way that the requisite dimensional stability can be obtained, particularly in the region of 5 connecting masses, sealing grooves, etc., to a sufficient degree of accuracy.

During this process, high pressure and friction forces are transmitted from the article 5 to the calibration plate 17 in the region of guiding and abutment points of this type, causing increased abrasion at these predeterminable points and, as an additional consequence, an ever increasing dimensional variance.

Fig. 2 provides a simplified and enlarged diagram, in perspective, of the calibration plate 17 with the aperture 24 and the shaping surfaces 25 delimiting it, although for the sake of simplicity, the cross-sectional shape of the aperture 24 illustrated as an example is only one of a plurality of possible profiled cross 15 sections. The profiled cross section illustrated in this case is of a more or less T-

shape, receiving orifices 27 being recessed into the region of the transversely disposed section land of the calibration plate 17, in which at least one wear-

resistant insert 28 is inserted. The purpose of this wear-resistant insert 28 is to guide the article 5 with the requisite degree of accuracy for a longer period of JO time in the region of points subjected to high stress. To this end, the wear-

resistant inserts 28 are made from a different material from that used for the calibration plates 17, such as high-strength tool steels, sintered metals, ceramic, sintered ceramic, high-strength plastics or other high-strength materials, which exhibit a high resistance to abrasion. The essential factor is that the material of 25 the inserts 28 must be capable of withstanding the high degree of stress to which they are exposed during the cooling and calibration process and exhibit a sufficiently high resistance to abrasion, a capacity to withstand pressure and be such that they can be durably retained in the receiving orifices 27 of the calibration plate 17.

a) In this simplified diagram, the insert 28 is illustrated in the righthand region of the aperture 24 in a position prior to being inserted in the receiving orifice 27, from which it can be seen that the receiving orifice 27 is provided in the calibration plate 17 in an arrangement recessed back from the shaping surface 25 and is so 5 starting from the shaping surface 25 towards the direction away from the aperture 24. The receiving orifice 27 is bounded by several delimiting surfaces 29, extending between the end faces 30, 31 bounding the calibration plate 17 in a direction perpendicular thereto. Some of these delimiting surfaces 29 may also run parallel with one another. By preference, the receiving orifice 27 extends Jo betvveen the two end faces 30, 31 across a thickness 32 of the calibration plate 17. Accordingly, the delimiting surfaces 29 of the receiving orifice 27 may be formed in the calibration plate 17 to a high degree of accuracy using a simple and inexpensive production process, such as boring, milling or an erosion process, for example. In the embodiment illustrated as an example here, the 15 insert 28, illustrated in a very simplified form, has a retaining part 33 which is inserted in the receiving orifice 27, and at least one guide part 34 projecting into the aperture 24, the insert 28 being advantageously made as an integral piece.

The retaining part 33 additionally has at least one external face 35 directed JO towards the delimiting surface 29, the delimiting surface 29 of the receiving orifice 27 forming a guide arrangement 36 in conjunction with the external surface 35 of the retaining part 33, at least in certain regions. This guide arrangement 36 is preferably aligned parallel with the extrusion direction 6, enabling a longitudinal displacement and hence a relative displacement between 25 the insert 28 and the calibration plate 16. The purpose of this longitudinal displacement is to enable the insert 28, in particular the retaining part 33, to be inserted in the receiving orifice 27.

In the left-hand part of the aperture 24, the insert 28 is illustrated in a position JO inserted in the receiving orifice 27, the subsequent drawings provided a detailed

lit illustration of a variety of embodiments by means of which the insert is mounted or positioned in the receiving orifice 27.

The key factor in all of these examples of embodiments is that respectively co 5 operating limiting stops 37, 38 with stop surfaces 39, 40 are provided along a major part of the peripheral region, both in the region of the receiving orifice 27 and on the retaining part 33 of the insert 28, in order to fix the position and hence restrict displacement of the guide arrangement 36. This being the case, the individual inserts 28, in particular the retaining part 33, are inserted in the JO receiving orifice 27 and pushed in, starting from the first end face 30 along the delimiting surface 29 towards the other end face 31 of the calibration plate 17.

This longitudinal displacement continues until the stop surfaces 39, 40 of the co operating limiting stops 37, 38 reach their reciprocal abutment position, thereby preventing any longitudinal displacement in the extrusion direction 6.

The purpose of the co-operating limiting stops 37, 38 is to absorb forces acting on the insert 28 as the article 5 is fed through and to prevent the insert 28 from working loose from the receiving orifice 27 during operation as per specification.

These forces caused by movement of the article 5 in the extrusion direction 6 are 20 transmitted from it, in the same direction, to the insert 28. If one of these inserts 28 becomes damaged or worn, it is removed from the receiving orifice 27 in the direction opposite the extrusion direction 6 by means of a compression force in co-operation with the guide arrangement 36 and a new, unused insert 28 can then be inserted in the receiving orifice 27 - as described above.

To obtain a fixed position, it may additionally be of advantage to select a slight to more pronounced push-fit seating between the delimiting surfaces 29 of the receiving orifice 27 and the external faces 35 of the insert 28, because, in conjunction with the limiting stops 37, 38, only light forces need to be applied in JO the extrusion direction 6 to fix orposition the insert 28 sufficiently to prevent any

movement relative to the calibration plate 17 transversely to the extrusion direction 6.

Figs 3 to 5 provide a simplified, schematic diagram, on an enlarged scale, of one 5 possible and optionally independent embodiment of a retaining arrangement 41 in the region of the guide arrangement 36 between the receiving orifice 27 and the retaining part 33, the same reference numbers as those used in Figs.1 and 2 being used to denote the same parts.

to In the embodiment illustrated as an example here, the two stop surfaces 39, 40 are inclined relative to the end faces 30, 31, in particular in the direction of the second end face 31, in a tapering arrangement. This being the case, the stop surface 39 on the calibration plate 17 is arranged in the first end face 30 in the extrusion direction 6 and is provided in the form of a recess, for example.

In the embodiment illustrated as an example, the receiving orifice 27 is provided in the form of an orifice 42 arranged at a distance from the shaping surface 25 of the aperture 24 and a gap 43 linking the orifice 42 to the shaping surface 25. By preference, the orifice 42 is a bore of the type which may be made by a whole no range of manufacturing techniques. Clearly, the orifice 42 may be of any shape in cross section, any may be freely selected depending on the application and geometric requirements. This being the case, the cross section of the orifice 42 may be in the shape of an ellipse, multi-sided or polygonal and may be made up of any combination of a variety of shaping surfaces. For reasons specific to the 25 manufacturing technology used, it may be of advantage if the orifice 42 is of a cylindrical shape, in which case it can be simply and inexpensively produced. If the shaping is imparted by a wire erosion process, it would naturally be possible to apply any other threedimensional shape, the essential factor being that the delimiting surfaces 29 should run in the same longitudinal extension or so longitudinal direction as and parallel with the extrusion direction 6. When the insert 28 is in the position in which it is inserted in the receiving orifice 27, the

stop surfaces 39 and 40 are arranged in a transition region between the first end face 30 and the delimiting surface 29 of the receiving orifice 27.

As may also be seen from the diagram in Fig. 5, a width 44 of the gap 43 is s smaller in a direction perpendicular to its longitudinal extension than a dimension 45 of the orifice 42 in the same direction. As result of this size difference, the external surface 35 is supported against the delimiting surface 29 in the region of the first end face 30 in the transition region between the retaining part 33 and the guide part 34, as indicated in Fig. 3 by a force - arrow F - acting on the guide part to 34 in its first end region 46. The difference in size between the width 44 of the gap 43 and the internal dimension 45 of the orifice 42 must be selected so as to be appropriate to the insert 28 in terms of its strength, particularly the transition region between the retaining part 33 and the guide part 34, as well as the supporting force transmitted into the calibration plate 17 from the external surface is 35 to the delimiting surface 29 in the region of the first end face 30 as the article 5 is fed through.

As described above, the calibration plate 17 is of a thickness 32 between the two end faces 30, 31, the insert 28 being slightly shorter in length 48 in the same JO spatial direction between the first end region 46 and another end region 47.

Consequently, the thickness 32 of the calibration plate 17 is larger than the length 48 of the insert 28 in the direction of the guide arrangement 36. It is of advantage if one of the two end regions 46,47 is aligned flush with or recessed relative to one of the two end faces 30, 31 of the calibration plate 17, once the 25 insert 28 is in the inserted position in the calibration plate 17. In order to prevent one of the end regions 46,47 of the insert 28 projecting beyond the calibration plate 17 if there is a slight shift of the insert 28 relative to the calibration plate 17, it is of advantage to select the length 48 of the insert 28 so that when in the inserted position, the two end regions 46,47 are respectively aligned set back 30 from the two end faces 30,31.

on If the orifice 42 is cylindrical in shape, the retaining part 33 of the insert 28 should also be of a cylindrical design in its longitudinal extension. As also illustrated, the gap 43 has gap walls 49, 50 aligned parallel with one another, against which the guide part 34 joined to the retaining part 33 moves in abutment, at least in certain 5 regions.

On the insert 28, in particular the retaining part 33, the counterpart to the limiting stop 37 of the calibration plate 17 is the limiting stop 38 which has on its first end region 46 directed towards the first end face 30 a projection 51 projecting beyond to the external face 35 and forming the stop surface 40. This projection 51 with the stop surface 40 may be of a design complementing the stop surface 39 of the calibration plate 17, thereby supporting the two limiting stops 37, 38 with their stop surfaces 39, 40 across a major part of the periphery. Displacement during insertion is continued until the two stop surfaces 39, 40 co-operating with one 15 another reach an abutting position and thereby check displacement. The insert 28 can be removed from the calibration plate 17 with very little effort by a simple displacement in the opposite direction and a new insert 28 placed in the receiving orifice 27 again.

so As also illustrated in this embodiment, at least two ribs 52, 53 are provided on the retaining part 33 of the insert 28, projecting beyond and delimiting the external surface 35 by means of their rib surfaces 54, 55, which extend, at least in certain regions, along the length 48 between the first and the other end region 46, 47 of the insert 28. The two ribs 52, 53 are arranged on the insert 28 in the immediate as vicinity of or transition region between the retaining part 33 and the guide part 34.

However, it would naturally also be possible for several of these ribs 52, 53 to be distributed around the periphery of the retaining part 33, as will be explained in more detail below.

So As may also be seen from the diagram of Fig. 4, a protuberance 56 of the rib 52, 54 beyond the external surface 35 of the insert 28 and retaining part 33 is

designed so that it becomes smaller along its longitudinal run or longitudinal extension, in particular constantly decreases, from the first end region 46 to the other end region 47. The protuberance 56 of the ribs 52, 53 is selected so that during the process of inserting the insert 28 in the receiving orifice 27 of the 5 calibration plate 17, the ribs 52, 53 plastically deform and retain the material of the calibration plate, causing durable recesses complementing the ribs to be formed permanently in the delimiting surfaces 29 of the receiving orifice 27.

These recesses are in turn delimited by or formed from matching surfaces directed towards and immediately adjacent to or adjoining the rib surfaces 54, 55.

JO These recesses are formed in certain regions of the receiving orifice 27 during the insertion process, as indicated by the broken lines of Fig. 5. The height of the protuberance 56 above the external surface 35 will depend on the number of ribs 52, 53 on the regaining part 33 and may be between 0.05 mm and 1.5 mm, preferably between 0.1 mm and 0.5 mm.

As a result of.the decrease in the protuberance and the preferably conical arrangement and alignment of the rib surfaces 54, 55 relative to one another, a pressing force is applied by the retaining part 33 - in the direction of arrow 57 against the delimiting surface 29 farthest from the shaping surface 25 starting 20 from the rib surface 54 directed towards the shaping surface 25, as a result of which an accurate push-fit seating of the insert 28 is obtained in the receiving orifice 27. This plastic deformation in the region of the ribs 52, 53 provides an additional positional fixing means and seats the insert 28 firmly relative to the calibration plate17.

In order to facilitate the process of deforming the material of the calibration plate 17, it is of advantage if the ribs 52, 53 have a preferably conical cross section in a plane perpendicular to their longitudinal extension, tapering in the direction facing away from the external surface 35. This being the case, the cone angle so between the rib surfaces 54, 55 may be of an acute, right-angled and optionally

obtuse design, freely selectable depending on the choice of material used for the insert 28 in conjunction with the material of the calibration plate 17.

As a result of the tapering design along the longitudinal extension of the ribs 52, 53, the first rib surface 54 of the ribs 52, 53 directed towards the shaping surface 25 assigned to the receiving orifice 27 is aligned at an angle relative thereto.

Consequently, the rib is wedge-shaped both in its cross section and in its longitudinal extension so that an increasingly strong plastic deformation or re shaping of the material of the calibration plate 17 is obtained in the region of the JO receiving orifice 27 in conjunction with the with the protuberance 56 as the insertion displacement progresses. In order to ensure that the insertion procedure is uniform, it is of advantage if the two first rib surfaces 54 of the ribs 52, 53 lying closer to the aperture 24 are aligned parallel with one another and optionally in the same plane.

In order to accommodate the material pushed in by the ribs 52, 53 in the region of the receiving orifice 27, it is of advantage to provide a recess in the insert 28, at least in a transition region between the first rib surface 54 and the external surface 35 of the insert 28. If only these two ribs 52, 53 are provided in this JO transition region, for example, it is also of advantage to provide another recess 58 in the transition region between the other rib surface 55 and the external surface 35, in order to be able to accommodate the material of the calibration plate 17 also pushed in this region. This will prevent a mechanical positive fit between the insert 28 and the calibration plate 17 during the insertion process.

Irrespective of the above, it would also be possible for the stop surfaces 39,40 to be formed by the delimiting surfaces 29 and external surfaces 35 facing one another, at least in certain regions. Another option would be for the stop surfaces 39, 40 to be provided by means of the rib surfaces 54, 55 and the recesses with 30 the matching surfaces formed by the ribs 52, 53 in the receiving orifice 27, at least in certain regions.

o As may also be seen by looking at Figs. 3 and 4 together, particularly with respect to the insert 28, the latter is provided with at least two ribs 59, 60 standing proud of the external surfaces 35 on the section cooperating with and 5 directed towards the gap 43 of the receiving orifice 27, which again have a decreasing or tapering cross section starting from the first end region 46 towards the other end region 47, in which case the protuberance above the external surface 35 will depend, as with the two ribs 52, 53, on the tolerances between the insert 28 and the receiving orifice 27, as well as the fixed seating to be JO obtained in the inserted position in the calibration plate 17. The greater the protuberance 56, the more the material of the calibration plate 17 can be plastically deformed and forced during the insertion process and the greater the recess 58 will be on either side of the rib surfaces 54, 55 of the ribs 52, 53 and rib surfaces 61, 62 of the ribs 59, 60. Likewise, the wedge-shaped cross section 15 described above as well as the choice of the wedge angle in the two ribs 59, 60 may be as described above with reference to ribs 52, 53.

As may best be seen from the diagram of Fig. 4, the ribs 52, 53 and 59, 60 have a wedge-shaped cross section tapering across their longitudinal extension in the JO region between the two end regions 46, 47, as a result of which the rib surfaces 54, 55 and 61, 62 of the ribs 52, 53 and 59, 60 run in alignment with one another across the longitudinal extension of the insert.

As a result of this wedge-shaped design across the longitudinal extension, the :s material of the calibration plate 17 remains plastically deformed to an increasing degree as the insertion displacement progresses, thereby enabling an increasingly large fixed seating to be obtained for the insert 28 in the receiving orifice 27.

JO In the region of the guide part 34 co-operating with the gap walls 49, 50 of the gap 43, the insert 28 has support surfaces 63, 64 complementing the latter,

which, in the embodiment illustrated as an example here, are also aligned parallel with one another and parallel with the two gap walls 49, 50.

The broken lines shown in the region of the guide part 34 in Fig. 4 illustrate yet s another of many possible ways in which the guide part 34 locates in or sits against the article 5. In this embodiment, the guide part 34 overall is substantially L-shaped. Irrespective of the above, the broken lines indicated in Fig. 5 illustrate another JO alternative, whereby the gap walls 49, 50 bounding the gap 43 taper in a plane disposed perpendicular to its longitudinal extension, starting from the orifice 42 to the shaping surface 25 of the aperture 24 co-operating with the receiving orifice 27. 15 Figures 6 to 9 illustrate another possible embodiment of the insert 28 and the way in which it is retained or received in the calibration plate 17, which may optionally be construed as an independent embodiment, the same reference numbers as those used in Figs. 1 to 5 described above being used to denote same parts. In order to avoid unnecessary repetition, reference may be made to JO the description given above in respect of Figs. 1 to 5.

Unlike the design described with reference to Figs. 3 to 5, the limiting stop 38 of the insert 28 with a stop surface 40 is disposed not in the first end region 46 but in the other end region 47. This limiting stop 38 with its stop surface 40 is 25 provided in the region of the retaining part 33 in the form of a region which tapers relative to the external surface 35 or an offset 65, which, in this particular case, extends across the entire cross-section region of the retaining part 33 to the guide part 34.

JO Accordingly, in the longitudinal extension of the insert 28, the retaining part 33 is shorter in longitudinal extension than the guide part 34. The counterpart to this

\ limiting stop 38 can be seen in the diagram of Figs. 8 and 9 in the region of the calibration plate 17, where the receiving orifice 27 with its delimiting surface 29 does not penetrate the calibration plate 17 across its entire thickness 32 in the totality of its cross section. Disposed in the region of the other end face 31 is a 5 shoulder 66 projecting into the receiving orifice 27, which stands proud of the delimiting surface 29 of the receiving orifice 27 by a height 67. The stop surface 39 of the limiting stop 37 is spaced at a distance 68 starting from the other end face 31 in the direction of the first end face 30. In the embodiment illustrated as an example here, the two stop surfaces 39, 40 are aligned parallel with the two to end faces 30, 31 of the calibration plate 17. It would naturally also be possible, as indicated by the broken lines shown in the region of the shoulder 66 in Fig. 9, for the stop surface 39 to be inclined, preferably tapering towards the other end face 31. 15 As described above, the choice of length 48 of the insert 28 relative to the thickness 32 of.the calibration plate 17 is made taking account of the layout and alignment of the co-operating stop surfaces 37, 38, so as to prevent the end regions 46, 47 standing proud of one of the end faces 30, 31 of the calibration plate 17 in the inserted position under all circumstances. If several calibration JO plates 17 were to be placed one above the other, the fact of choosing high-

strength materials for the insert 28 would cause damage to the calibration plates 17 and possibly cause the insert 28 to work loose from its seat in the receiving orifice 27.

25 As illustrated in Fig. 6, several ribs 52, 53 are distributed around the periphery of the retaining part 33. Their design may be as described in respect of the embodiments illustrated in the other drawings.

The gap 43 linking the orifice 42 to the shaping surface 25 in this embodiment is So designed so that gap walls 49, 50 widen in a plane aligned perpendicular to the longitudinal extension of the gap 43 from the orifice 42 or delimiting surface 29 to

the shaping surface 25 of the aperture 24 co-operating with the receiving orifice 27. These widening gap walls 49, 50 may be of a planar or curved design but run in a vertical direction between the two end faces 30, 31. In the ennbodiment illustrated as an example in Fig. 8, the gap walls 49, 50 are shaped in the form of 5 segments of a cylindrical surface.

As also illustrated in Fig. 6, support surfaces 63, 64 extending so as to complement the two gap walls 49, 50 of the gap 43 are provided on the guide part 34, projecting beyond the guide part 34 transversely to its longitudinal Jo extension and preferably running end to end across the length 48 of the guide part 34. The shape and design of the guide part and its protuberance above the shaping surface 25 towards the aperture 24 can be freely selected depending on the shape of the article 5 to be calibrated and on the prevailing circumstances.

i5 Figs. 10 to 13 illustrate another alternative and optionally independent design of the insert 28 and the receiving orifice 27 in the calibration plate 17, the same reference numbers as those used for the description of Figs. 1 to 9 above being

used for the same parts. Again, for the sake of avoiding unnecessary repetition, reference may be made to the description of Figs. 1 to 9 above.

The embodiment of the insert 28 illustrated here is similar to the embodiment described and explained with reference to Figs. 6 and 7, but unlike this embodiment, the gap 43 is designed with its delimiting gap walls 49, 50 running parallel with one another end to end, the support surfaces 63, 64 also being 25 parallel and without any protuberance in that section of the guide part 34 facing the gap 43.

The design of the limiting stops 37, 38 and the stop surfaces 39, 40 provided thereon as well as the design and layout of the individual ribs 52, 53 with the 30 recesses 58 optionally provided in between them, may be the same as those described in detail with reference to Figs. 6 to 9.

Figs. 14 and 15 illustrate yet another alternative and optionally independent design of the insert 28 for inserting in a receiving orifice 27, not illustrated in detail, of the calibration plate 17, the same parts again being shown by the same 5 reference numbers as those used for Figs. 1 to 13 above. As this design of the insert 28 is similar to the design described above with reference to Figs. 6 and 7 as well as 10 and 11, reference may be made to the more detailed description of

these drawings.

JO The retaining part 33 with its external surface 35 again has several ribs 52, 53 distributed around the periphery, between which recesses 58 may also be provided in the external surface 35. Similarly, the support surfaces 63, 64 may be aligned parallel with one another in the region directed towards the gap 43 as described above with reference to Figs. 10 to 13.

The limiting stop 38 is again provided in the other end region 47 of the insert 28, the stop surface 40 being designed in the form of a circle segment by providing the offset 65. This stop surface 40 is provided with the stop surface 39, not illustrated in detail, in the region of the limiting stop 37, which may be provided on JO the calibration plate 17 in the form of the shoulder 66.

In the embodiments of the retaining part 33 illustrated in Figs. 3 and 4, 6 and 7, as well as 10 and 11, the latter is substantially circular in cross section in a plane perpendicular to its longitudinal extension, so that the retaining part 33 is of a 25 cylindrical shape across a major part of its periphery in the direction of its longitudinal extension.

Figs. 16 and 17 illustrate another, optionally independent embodiment of the insert 28, the same parts being denoted by the same reference numbers as JO those used above with reference to Figs, 1 to 15. Again, in order to avoid

unnecessary repetition, reference may be made to the detailed description given

above with respect to Figs. l to 15.

The insert 28 is of a similar design in the region of its guide part 34 as that 5 described with reference to Figs. 6 to 9 above. Projections 69 stand proud of the retaining part 33 on either side of its longitudinal extension, the support surfaces 63, 64 on these projections 69 complementing the widening gap 43 in the calibration plate 17 with the gap walls 49, 50. Ribs 52, 53 are again provided on either side of a plane of symmetry 70 in the region of the retaining part 33, which to are fixed in terms of their three-dimensional shape by rib surfaces 54, 55 co operatinn therewith. in this case; the first rib surfaces 54 directed towards the guide part 34 and the shaping surfaces 25 of the aperture 24 are aligned parallel with one another and in a simply and schematically indicated plane 71 perpendicular to the plane of symmetry 70.

The two rib surfaces 54, 55 delimiting the ribs 52, 53 are again disposed at an acute angle to one another in the direction perpendicular to their longitudinal extension. Clearly, the rib surfaces could also be disposed at a right-angle or obtuse angle relative to one another. Likewise, as may be seen by studying Figs. JO 1 6 and 17 in conjunction with one another, the rib surfaces 54 run at an angle 72 relative to one another starting from the first end region 46 in the direction of the other end region 47, a distance 73 in the first end region 46 starting from a recess in the external surface 35 between the former and the rib surface 54 being greater than a distance 74 in the same direction in the other end region 47.

25 This crest runs in the region of the imaginary intersection of the plane of symmetry 70 with the external surface 35. As a result of this angled layout, which could also be described as decreasing from the first end region 46 towards the other end region 47 in the diagram given here, a constantly increasing pressing force is produced, starting from the external surface 35 of the retaining part 33, JO on the delimiting surface 29 of the receiving orifice 27 co-operating therewith during the insertion procedure. This enables an exact protuberance of the guide

part 34 to be obtained above the shaping surface 25 in the direction of the aperture 24. Likewise, the insert 28 is firmly fixed in the receiving orifice 27 as a result of its retaining force. By preference, the size of the angle 72 is selected so that it imparts a self-locking action to the insert 28 in the receiving orifice 27. The 5 limiting stop 38 in the region of the retaining part 33 is again provided in the form of the offset 65 with the stop surface 40.

However, the two different embodiments of the limiting stops 37 and 38, described with reference to Figs. 3 to 5 and 6 to 17, could be used in any to combination with one another and may be provided simultaneously on one of the retaining parts 28. This may be the case, for example, if high support forces are applied from the article 5 on the insert 28 in order to ensure that the force transmitted is sufficient and reliable to ensure a secure hold.

15 Figs. 18 to 20 provide a simplified illustration of another insert 28 in a receiving orifice 27 of the calibration plate 17, the same parts being used by the same reference numbers as those used with reference to Figs. 1 to 17. Reference may also be made to Figs. 1 to 17 for details of the design of limiting stops 38, 39 used to restrict the longitudinal displacement of the guide arrangement 36.

The insert 28 illustrated in this case is designed so that a bearing surface 75 directed towards the aperture 24 is disposed in a substantially planar arrangement relative to the shaping surface 25 of the aperture. This particular insert 28 is designed so that it can be inserted particularly deeply in the region of 25 shaping surfaces 25 subjected to a high degree of stress in order to avoid wear and hence dimensional instability during the process of manufacturing the article 5 over a longer period of time and to enable a replacement to be inserted rapidly.

In the first end region 46 of the insert 28, the projection 51 is provided in at least 30 certain regions around the periphery of the retaining part 33, forming the limiting stop 38 with the stop surface 40. Complementing it in the region of the first end

(A face 30 of the calibration plate 17 is the limiting stop 37 with the stop surface 39, as illustrated in simplified format in the left-hand part of Fig.20.

Substantially parallel with the stop surface 75, the retaining part 33 has the 5 external surface 35, directed towards the delimiting surface 29 of the receiving orifice 27. In the lateral transition region between the surfaces arranged substantially parallel with one another, namely the stop surface 75 and the external surface 35, at least one but preferably a plurality of ribs 52, 53 is provided, which, in addition to restricting longitudinal displacement, in turn ensure to that the insert 28 is securely retained or fixed in the receiving orifice 17, thereby guaranteeing a defined alignment of the stop surface 75 relative to the article 5 to be aligned.

The key factor in all the different embodiments described above is that the 15 limiting stop 37, 38 is provided at least in certain regions between the retaining part 33 and the receiving orifice 27 by means of a positive fit between these parts. This can be achieved by providing the stop surfaces 39, 40 in at least certain regions in the form of the delimiting surfaces 29 and external surfaces 35 facing one another. In addition to and irrespective of the above, this positive fit 20 may also be afforded by means of ribs 52, 53, 59 and 60 provided on the insert in conjunction with the recesses formed in the receiving orifice 27. Another possibility is to design the receiving orifice 27 and the retaining part 33 in a double-cone design.

25 Fig. 21 is a simplified diagram of a part-region of the calibration plate 17 with the insert 28 retained therein and the article 5 being guided by the insert 28, the same parts being denoted by the same reference numbers as those used for Figs.1 to 20 above.

JO As shown in this simplified illustration, one insert 28 can easily be replaced with another due to the almost identical three-dimensional shape in the region of the

retaining part 33 if it is desirable to shift the position of the guide part 34 relative to the receiving orifice 27, particularly transversely to the extrusion direction 6 and/or to use a design of a different size, e.g. to increase or reduce the width transversely to the extrusion direction 6. In the event of a shift to one side, a 5 compression force can be selectively applied to a part region of the article 5, for example, in order to obtain the desired alignment of the article 5 in this section during the cooling process, thereby obtaining the requisite dimensional stability of the article 5 without the need for any unduly complex work or alignment in the region of the calibration plates 17 simply by changing the inserts 28.

The different options described above are illustrated by lines of different formats (broken, dotted-dashed lines).

Finally, for the sake of good order, it should be pointed out that in order to 15 provide a clearer understanding of the structure of the calibration plate with the insert and the way it is retained, they andtheir respective parts are illustrated to a certain degree out of scale and/or on an enlarged and/or reduced scale.

The independent solutions proposed by the invention and the underlying task to may be found in the description.

Above all, the individual embodiments illustrated in Figs. 1; 2; 3 to 5; 6 to 9; 10 to 13; 14, 15; 16, 17; 18 to 20; 21 may be construed as independent solutions to the subject matter proposed by the invention. The relevant tasks and the solutions 25 proposed by the invention may be taken from the detailed descriptions of these

drawings.

Claims

c: CLAIMS

1. Calibration plate for a shaping device of an extrusion system, said plate comprising end faces spaced at a distance apart from one another in the extrusion direction, and at least one aperture extending between said end faces and having shaping surfaces through which an extruded article is fed, the 5 shaping surfaces delimiting an external profiled cross section of the article to be fed through, at least in certain regions, and being provided with at least one receiving orifice recessed into the calibration plate and extending from the shaping surface towards the aperture, said at least one receiving orifice having delimiting surfaces extending between the end faces, and at least one wear o resistant insert with a retaining part inserted in the receiving orifice, at least certain regions of the delimiting surfaces and external surface of said retaining part forming a guide arrangement, wherein co-operating limiting stops with stop surfaces for the guide arrangement are provided around a major part of a peripheral region both in the region of the receiving orifice and on the retaining 15 part.

2. Calibration plate as claimed in claim 1, wherein the stop surfaces are aligned parallel with the end faces.

ho 3. Calibration plate as claimed in claim 1, wherein the stop surfaces are inclined, in particular are disposed so as to taper towards the second end face.

4. Calibration plate as claimed in claim 1, 2 or 3, wherein the stop surfaces are provided in the form of delimiting surfaces and external surfaces directed 25 towards one another, at least in certain regions.

5. Calibration plate as claimed in any preceding claim wherein the stop surfaces are spaced by a distance back from a second end face towards a first end face and are arranged on a shoulder projecting into the receiving orifice.

5 6. Calibration plate as claimed in any preceding claim, wherein the stop surfaces are disposed in a transition region between a first end face and the delimiting surface of the receiving orifice.

7. Calibration plate as claimed in any preceding claim, wherein, on an end to region of the retaining part directed towards one end face, the retaining part has a tapered region or offset from its external surface forming the stop surface.

8. Calibration plate as claimed in any preceding claim, wherein the retaining part has a projection standing proud of the external surface on its first end region 15 directed towards a first end face forming the stop surface.

9. Calibration plate as claimed in any preceding claim, wherein, in addition to the retaining part, the insert has at least one guide part projecting into the aperture. 10. Calibration plate as claimed in any preceding claim, wherein the receiving orifice has an orifice spaced at a distance from the shaping surface and a gap linking the orifice to the shaping surface.

25 11. Calibration plate as claimed in claim 10, wherein the orifice is provided in the form of a bore.

12. Calibration plate as claimed in claim 10 or 11, wherein a width of the gap is shorter in the direction perpendicular to its longitudinal extension than a 30 dimension of the orifice in the same direction.

\ 13. Calibration plate as claimed in claim 10, 11 or 12, wherein gap walls delimiting the gap are aligned parallel with one another.

5 14. Calibration plate es claimed in claim 10, 11, 12, or 13, wherein gap walls bounding the gap are aligned in a plane perpendicular to the longitudinal extension thereof and widen starting from the orifice through to the shaping surface of the orifice assigned to the receiving orifice.

to 15. Calibration plate as claimed in any one of claims 10 to 14, where gap walls bounding the gap are provided in the form of segments of a cylindrical surface. 16. Calibration plate as claimed in any one of claims 10 to 13 or 1 5, wherein 15 gap walls bounding the gap are designed so as to taper in a plane perpendicular to the longitudinal extension thereof, starting from the orifice through to the shaping surface of the aperture assigned to the receiving orifice.

17. Calibration plate as claimed in any one of claims 10 to 16, wherein support no surfaces are provided on the insert in the region of the gap extending so as to complement gap walls delimiting the gap.

18. Calibration plate as claimed in any preceding claim, wherein at least two ribs with adjoining rib surfaces are provided on the retaining part standing proud :s of the external surface and extend between first and second end regions at least in certain regions.

19. Calibration plate as claimed in claim 18, wherein at least two of the ribs are arranged on the insert in a transition region between the retaining part and a so guide part thereof.

20. Calibration plate as claimed in claim 18 or 19, wherein a plurality of ribs are distributed around the periphery of the retaining part.

5 21. Calibration plate as claimed in any one of claims 18 to 20, wherein a protuberance of the ribs standing proud of the external surface of the insert decreases across its longitudinal extension from the first to the second end region. to 22. Calibration plate as claimed in any one of claims 18 to 21, wherein each rib has a wedge-shaped cross section in a plane disposed perpendicular to the longitudinal extension of the insert, which tapers in the direction facing away from the external surface.

15 23. Calibration plate as claimed in any one of claims 18 to 22, wherein two rib surfaces of the ribs are disposed running towards one another across the longitudinal extension of the insert.

24. Calibration plate as claimed in any one of claims 18 to 23, wherein two 20 first rib surfaces of the ribs lying closer to the orifice are aligned parallel with one another. 25. Calibration plate as claimed in claim 24, wherein two first rib surfaces are arranged in a same plane receiving the latter.

26. Calibration plate as claimed in any one of claims 18 to 25, wherein a recess is provided in the insert at least in a transition region between a first rib surface and the external surface of the insert.

27. Calibration plate as claimed in any preceding claim, wherein at least two ribs standing proud of the external surfaces are provided on the insert on the section co-operating with a gap linking the receiving orifice to the shaping surface. 28. Calibration plate as claimed in any preceding claim, wherein the stop surfaces are provided in the form of rib surfaces and recesses are formed in the receiving orifice by ribs, at least in certain regions.

29. Calibration plate as claimed in any preceding claim, wherein the retaining part of the insert is of a cylindrical shape in its longitudinal extension.

30. Calibration plate as claimed in any preceding claim, wherein the insert is made as an integral piece.

31. Calibration plate as claimed in any preceding claim, wherein a thickness thereof between the end faces is larger than a length of the insert between its end regions.

so 32. Calibration plate as claimed in any preceding claim, wherein, when the insert is in the position inserted in the calibration plate, one of two end regions thereof is disposed flush with or recessed back from one of the two end faces.

33. Calibration plate as claimed in any one of claims 1 to 31, wherein, when 25 the insert is in the position inserted in the calibration plate, two end regions thereof are disposed set back from the end faces.

34. Calibration plate as claimed in any preceding claim, wherein the insert is provided with ribs, and the material used therefor in the region of the ribs is so permanently plastically deformed, at least in certain regions.

35. Calibration plate as claimed in any preceding claim, wherein the delimiting surfaces of the receiving orifice extend between the two end faces in a direction perpendicular thereto.

s 36. Calibration plate for a shaping device of an extrusion system, said calibration plate being substantially as herein described with reference to Figures 1; 2; 3 to 5; 6 to 9; 10 to 13; 14, 15; 16, 17; 18 to 20; 21 of the accompanying drawings.