Abstract
The invention relates to an extrusion nozzle for an extrusion device for extruding plastic profiles, having at least one nozzle plate (1) which has at least one flow channel (2) for plastic melt, and at least one insert element (4) which is inserted into the at least one flow channel (2) in order to reduce a cross-sectional area of the at least one flow channel (2) through which the plastic melt can flow. At least one holding device (3) is provided in the at least one flow channel (2), on which the at least one insert element (4) is arranged.
Claims
1. Extrusion nozzle for an extrusion device for extruding plastic profiles, having at least one nozzle plate (1) which has at least one flow channel (2) for plastic melt, and at least one insert element (4) which is inserted into the at least one flow channel (2) in order to reduce a cross-sectional area of the at least one flow channel (2) through which the plastic melt can flow, characterized in that at least one holding device (3) is provided in the at least one flow channel (2), on which the at least one insert element (4) is arranged.
2. Extrusion nozzle according to claim 1, characterized in that the at least one holding device (3) is arranged inside the at least one flow channel (2).
3. Extrusion nozzle according to one of claim 1 or 2, characterized in that the cross-sectional area of the at least one flow channel (2) through which the plastic melt can flow can be reduced transversely to an extrusion direction (E) along which the plastic melt can flow through the at least one flow channel (2) by means of the at least one insert element (4).
4. Extrusion nozzle according to any one of claims 1 to 3, characterized in that the at least one insert element (4) is detachably inserted into the at least one holding device (3).
5. Extrusion nozzle according to one of the preceding claims, characterized in that the at least one holding device (3) is moulded onto a surface (20) of the at least one flow channel (2) along which the plastic melt can flow.
6. Extrusion nozzle according to one of the preceding claims, characterized in that the at least one holding device (3) forms at least one undercut by means of which the at least one insert element (4) is positively fixed to the at least one holding device (3) perpendicular to an extrusion direction (E) along which the plastic melt can flow through the at least one flow channel (2).
7. Extrusion nozzle according to one of the preceding claims, characterized in that the at least one holding device (3) forms a receptacle (30) into which the at least one insert element (4) can be inserted.
8. Extrusion nozzle according to claim 7, characterized in that the at least one insert element (4) is held in a force-fitting and/or form-fitting manner on the holder (30) along an extrusion direction (E) along which the plastic melt can flow through the at least one flow channel (2).
9. Extrusion nozzle according to any one of the preceding claims, characterized in that said at least one holding device (3) comprises two webs (31, 32) projecting from a surface (20) of said at least one flow channel (2).
10. Extrusion nozzle according to claim 9, characterized in that the two webs (31, 32) extend obliquely to an extrusion direction (E) along which the plastic melt can flow through the at least one flow channel (2).
11. Extrusion nozzle according to one of the preceding claims, characterized in that the at least one insert element (4) is wedge-shaped along an extrusion direction (E) along which the plastic melt can flow through the at least one flow channel (2).
12. Extrusion nozzle according to any one of the preceding claims, characterized in that the at least one insert element (4) comprises a base part (41) for arrangement on the at least one holding device (3) and a head part (42) for moulding the plastic melt.
13. Extrusion nozzle according to claim 12, characterized in that the base part (41) is formed in cross-section as a symmetrical trapezium.
14. Extrusion nozzle according to one of the claim 12 or 13, characterized in that the head part (42) protrudes from the base part (41) in a tongue-shaped or T-shaped cross-section.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the following, embodiments of the extrusion nozzle are described with reference to figures.
[0024] FIG. 1 shows a perspective view of a nozzle plate with a flow channel.
[0025] FIG. 2A shows a top view of a holding device.
[0026] FIG. 2B shows a cross-section through a holding device.
[0027] FIG. 3A shows a top view of an insert element.
[0028] FIG. 3B shows a cross-section through an insert element.
[0029] FIG. 4A shows a top view of a holding device on which an insert element is arranged.
[0030] FIG. 4B shows a cross-section through a holding device and an insert element.
[0031] FIGS. 5A-5D show perspective views of a nozzle plate with a flow channel and an insert element.
[0032] FIG. 6 shows a view of an extrusion nozzle with multiple nozzle plates.
[0033] FIG. 7 shows a cross-section through a nozzle plate with several flow channels.
DETAILED DESCRIPTION
[0034] FIG. 1 shows a nozzle plate 1 with a flow channel 2 for plastic melt. An insert element 4 is inserted into the flow channel 2, which reduces the cross-sectional area of the flow channel 2 through which the plastic melt can flow. The plastic melt has a smaller volume available for flowing through the flow channel 2 due to the inserted insert element 4. The insert element 4 protrudes from a surface 20 of the flow channel 2 along which the plastic melt flows. It protrudes into the flow of the plastic melt. The molten plastic thus suffers frictional losses at the insert element 4, so that a flow velocity of the molten plastic is reduced. The insert element 4 projects from a first side of the flow channel 2 towards an opposite second side of the flow channel 2. A height of the insert element 4 above the surface 20 of the flow channel 2 at which the insert element 4 is arranged is less than a distance between the first and second sides. A distance between two sides of the flow channel 2 is therefore not completely filled by the insert element 4. In particular, the insert element 4 is only held on one side of the flow channel 2. The insert element 4 reduces the cross-sectional area through which the plastic melt can flow transversely to the extrusion direction E along which the plastic melt flows through the flow channel 2.
[0035] A holding device 3 is provided in the flow channel 2, on which the insert element 4 is arranged. The holding device 3 is designed to hold the insert element 4. In particular, the holding device 3 holds the insert element 4 against the extrusion direction E, so that the insert element 4 is not carried along by the plastic melt. The holding device 3 is arranged inside the flow channel 2. It protrudes from the surface 20 of the flow channel 2 in the direction of the plastic melt. The flow channel 2 forms an approximately cuboid-shaped cavity at the nozzle plate 1. The holding device 3 forms a projection into the flow channel 2 extending longitudinally along the extrusion direction E. The insert element 4 is clamped to the holding device 3. The insert element 4 is also longitudinally extended along the extrusion direction E. A cross-sectional area of the insert element 4 along the extrusion direction E is larger than a cross-sectional area of the insert element 4 transverse to the extrusion direction E.
[0036] FIG. 2A shows a top view of a section of the surface 20 of the flow channel 2 on which the holding device 3 is arranged. FIG. 2B shows a cross-section through the holding device 3. The holding device 3 is moulded onto the surface 20 of the flow channel 2 along which the plastic melt can flow. It comprises two webs 31, 32, each of which protrudes from the surface 20 in the shape of a ridge. A receptacle 30 for the insert element 4 is formed between the webs 31, 32. The insert element 4 can be held on the receptacle 30 along the extrusion direction E in a force-fitting and form-fitting manner.
[0037] Two undercuts are formed on the holding device 3, via which the insert element 4 can be form-fittingly fixed to the holding device 3. The undercuts form-fittingly fix the insert element 4 in particular in a plane perpendicular to the extrusion direction E. To form the undercuts, the webs 31, 32 each have a retaining section 310, 320, which is longitudinally extended along the extrusion direction E. The retaining sections 310, 320 each project obliquely from the surface 20 of the flow channel 2. An angle W2 between each of the retaining sections 310, 320 and the surface 20 is less than 90°. The retaining sections 310, 320 are inclined towards each other. This allows the insert element 4 to be held positively on the holding device 3 in a plane perpendicular to the extrusion direction E.
[0038] FIG. 2A shows that the webs 31, 32 are arranged on the surface along the extrusion direction E at an angle W1 to each other. In particular, the webs 31, 32 are not aligned parallel to each other. The angle W1 between the webs 31, 32 in a plane parallel to the surface 20 of the flow channel 2 on which the webs 31, 32 are arranged may be in an interval between 0.5° and 10°. The small angle W1 ensures that the receptacle 30 is wedge-shaped along the extrusion direction E. When plastic melt flows past the insert element 4 arranged on the holding device 3, the insert element 4 is pressed into the wedge-shaped receptacle 30 along the extrusion direction E by the plastic melt, so that the insert element 4 can be held on the receptacle 30 in such a way that it cannot be lost.
[0039] FIG. 3A shows a top view of an insert element 4. The insert element 4 is wedge-shaped along the extrusion direction E. Two end faces 440, 450 of the insert element 4 along the extrusion direction E are formed at an obtuse angle to allow the plastic melt to flow past the end faces 440, 450. In this way, an undesirable accumulation of plastic melt on the end faces 440, 450, as would be conceivable and possible, for example, with flat end faces, can be prevented. If molten plastic accumulates on one of the end faces 440, 450, there is a risk that the molten plastic will burn. The end faces 440, 450 can of course protrude from the insert element 4 along the extrusion direction E in any shape. For example, at least one of the end faces 440, 450 can be rounded or formed at an acute angle.
[0040] Side sections 401, 402 of the insert element 4, each facing one of the webs 31, 32, are arranged at an angle V1 oblique to each other. To insert the insert element 4 into the receptacle 30 of the holding device 3, the insert element 4 is pushed between the two webs 31, 32. Because the two webs 31, 32 are arranged at an angle to each other and the insert element 4 is wedge-shaped, the holding device 3 and the insert element 4 can be wedged together.
[0041] The angle V1 at which the side sections 401, 402 in the insert element 4 in FIG. 3A are arranged obliquely to each other is greater than the angle W1 at which the webs 31, 32 in the holding device 3 in FIG. 2A are arranged to each other.
[0042] FIG. 3B shows a cross-sectional view of the insert element 4. The insert element 4 comprises a base part 41 for placement on the holding device 3 and a head part 42 for moulding the molten plastic. The base part 41 has a base surface 430 adjacent to the surface 20 of the flow channel 2. Two side sections 401, 402 protrude from the base surface 430. The side sections 401, 402 each form an angle V2 of less than 90° to the base surface 430. The side sections 401, 402 are each inclined towards each other. The angle V2 between the base surface 430 and the side sections 401, 402 is in each case greater than the angle W2 between the surface 20 of the flow channel 2 and the holding sections 310, 320 of the webs 31, 32, so that the insert element 4 can be wedged with the holding device 3.
[0043] FIG. 4A shows a top view of the holding device 3 with insert element 4 arranged on the holding device 3. The insert element 4 protrudes from the holding device 3 along the extrusion direction E on two sides. It is inserted between the two webs 31, 32 of the holding device 3 until further advancement along the extrusion direction E is no longer possible due to a decreasing width of the receptacle 30 along the extrusion direction E. The holding device 3 and the insert element 4 are arranged inside the flow channel 1. They also do not protrude beyond the flow channel 1.
[0044] FIG. 4B shows a cross-section through the flow channel 2 with insert element 4 inserted therein. The holding device 3 is moulded onto the surface 20 of the flow channel 2. The insert element 4 is held to the holding device 3 via the base part 41. A first web 31 of the holding device 3 forms a first undercut for the base part, and a second web 32 of the holding device 3 forms a second undercut for the base part. A first retaining section 310 of the first web 31 is adjacent to a first side portion 401 of the base part 41. A second retaining section 320 of the second web 32 is adjacent to a second side portion 402 of the base part 41. As a result, the insert element 4 is releasably clamped between the two webs 31, 32 against the extrusion direction E.
[0045] FIG. 5A to FIG. 5D show different designs of the insert element 4. The base part 41 of the insert elements 4 shown is designed as an identical part, so that identical holding devices 3 can be used in each case to arrange the insert elements 4 on the flow channel 2. In particular, the base parts 41 are each wedge-shaped along the extrusion direction E. The different designs of the insert elements 4 can be used alone or in combination in at least one flow channel 2.
[0046] The insert element 4 shown in FIG. 5A is wedge-shaped. In particular, it has a head part 42 which is wedge-shaped along the extrusion direction E and whose height above the base part 41 is constant. The head part 42 is wedge-shaped in a first plane along the extrusion direction E and parallel to the surface of the flow channel 2 on which the insert element 4 is arranged, and has a rectangular cross-sectional surface in a second plane along the extrusion direction E and perpendicular to the surface. The head part 42 has a first flow surface 421, 422 and a second flow surface 422, each projecting from the base part 41. The molten plastic can flow along each of the flow surfaces 421, 422. The first and second flow surfaces 421, 422 are connected to each other via a third flow surface 423 disposed on a side of the head part 42 remote from the base part 41. The third flow surface 423 decreases in size along the extrusion direction E so that a flow velocity of a molten plastic flowing past the insert element 4 can increase along the extrusion direction E.
[0047] The insert element 4 shown in FIG. 5B has a head part 42 whose height above the base part 41 increases along the extrusion direction E. Due to the gradually increasing height of the head part 42 above the base part 41, a shape of the molten plastic flowing through the flow channel 2 can be gradually changed along the extrusion direction E. In addition, a flow velocity of the molten plastic flowing past the insert element 4 can decrease along the extrusion direction E.
[0048] The insert element 4 shown in FIG. 5C is elongated along the extrusion direction E and has a head part 42 with a first head part section 4201 extending in a plane perpendicular to the extrusion direction E along a first direction. The head part 42 has a second head part portion 4202 extending in a plane perpendicular to the extrusion direction E along a second direction arranged perpendicular to the first direction. The head part 42 is formed symmetrically relative to a plane along the extrusion direction E. In particular, the head part 42 is T-shaped in cross-section in the plane perpendicular to the extrusion direction. The first head part section 4201 protrudes from the base part 41 along the first direction. The second head part section 4202 is arranged on the first head part section 4201 at a side opposite to the base part 41. A width of the second head part section 4202 is determinable independently of a size of the holding device 3 or the base part 41. Thus, any shaped cross-sectional area of the flow channel 2 can be filled by the head part 42.
[0049] The first head part section 4201 has first and second flow surfaces 421, 422. The first and second flow surfaces 421, 422 are arranged obliquely to each other along the extrusion direction E and protrude from the base part 41. The second head part section 4202 has four flow surfaces 423, 424, 425, 426 along which the molten plastic can flow. Two flow surfaces 423, 424, 425, 426 are located opposite each other. A third flow surface 423 facing away from the base part 41 and a fourth flow surface 424 facing the base part 41 are arranged at an angle to each other. The first head part section 4201 adjoins the fourth flow surface 424, thereby dividing the fourth flow surface 424 into two portions. A distance between the third and fourth flow surfaces 423, 424 decreases along the extrusion direction E. The third and fourth flow surfaces 423, 424 are connected via fifth and sixth flow surfaces 425, 426 that face each other. A distance between the fifth and sixth flow surfaces 425, 426 decreases along the extrusion direction E. The second head part section 4202 is wedge-shaped in two planes, which are in particular perpendicular to each other and parallel to the extrusion direction E. The second head part section 4202 is wedge-shaped in two planes. In principle, the second head part section 4202 can also have four parallel flow surfaces or at least one pair of parallel flow surfaces.
[0050] The insert element 4 shown in FIG. 5D has a head part 42 which is asymmetrical relative to the plane along the extrusion direction E. In particular, the head part 42 is L-shaped in cross-section in the plane perpendicular to the extrusion direction. In particular, the head part 42 is L-shaped in cross-section in the plane perpendicular to the extrusion direction.
[0051] The second flow surface 422 is extended along a plane from the first head part section 4201 to the second head part section 4202. The third flow surface 423 has two grooves 46 for easy visual identification of the insert element 4. In principle, any number of grooves 46 may be provided to distinguish different embodiments of the insert element 4. The insert element according to the embodiment example of FIG. 5D fills a smaller cross-sectional area of the flow channel 2 than the insert element 4 according to the embodiment example of FIG. 5C. By selecting differently shaped insert elements 4, the filled cross-sectional area of the flow channel 2 for influencing the plastic melt can therefore be determined.
[0052] FIG. 6 shows an extrusion nozzle with seven nozzle plates 1, 1′, which have six flow channels 2, 2′ for plastic melt. A holding device 3 is arranged in each of the flow channels 2 on one of the nozzle plates 1. An insert element 4 is provided on the holding device 3 in each case, through which the flow channel 2 is reduced in size. As a result, only a fraction of the plastic melt that would flow through a flow channel 2 without the insert element 4 can flow through each of the reduced flow channels 2. Holding devices 4 and/or insert elements 4 can be provided on each of the flow channels 2, 2′ or also only on a part of the flow channels 2, 2′.
[0053] FIG. 7 shows a cross-section through a nozzle plate 1 with a plurality of flow channels 2. One, two or three holding devices 3 are arranged in a part of the flow channels 2. Thus, a plurality of holding devices 3 may be provided in the at least one flow channel 2. The plurality of holding devices 3 are each arranged on a common side of a flow channel 2. Alternatively or additionally, the holding devices 3 can be arranged on different sides of the flow channel 2, so that the insert elements 4 on the holding devices 3 are opposite each other and/or arranged perpendicular to each other. An insert element 4 is arranged on each of the holding devices 3. By arranging the insert elements 4 in the flow channels, a flow velocity of plastic melt through the flow channels 2 can be reduced. The plastic melt flows more slowly through a flow channel 2 with insert element 4, so that the wall thickness of the associated profile area is smaller.
