Device for the twist-free width change of a fiber strip passing through the device, and system having a plurality of such devices

Abstract

The invention relates to a device (1) for the twist-free width change of a fiber strip (2) of continuous fibers (3) passing through the device (1) to a specified effective width (8). The device (1) comprises a transport unit (4) for transporting the fiber strip (2). The device (1) further comprises at least one width change assembly (5) configured such that the width change assembly (5) transfers an initial distance (a) of two adjacent fibers (3) of the fiber strip (2) to a target distance (b) of adjacent fibers (3) of the fiber strip (2). For a large part of the pairs of adjacent fibers (3), the ratio between the target distance (b) and the initial distance (a) matches within a tolerance range of 20%. This results in a reliable and economical device.

Claims

1. A device for the twist-free width change of a fiber strip made of a plurality of continuous fibers passing through the device to a predefined width (B), comprising a transport assembly for transporting the fiber strip, at least one width change assembly which changes an initial spacing (a) of two adjacent fibers of the fiber strip to a target spacing (b) of adjacent fibers of the fiber strip, the ratio between the target spacing (b) and the initial spacing (a) for all pairs of adjacent fibers matching within a tolerance band of 20%; wherein the at least one width change assembly has: a first partially circular guide contour having a first contour radius that is located in an arrangement plane (yz) perpendicular to a transport direction (x) of the fiber strip, a second partially circular guide contour having a second contour radius which lies in a further arrangement plane (yz) perpendicular to the transport direction (x) of the fiber strip, the two partially circular guide contours being arranged coaxially, the fiber strip being guided over the two guide contours such that the individual fibers rest on both guide contours, the two guide contours following each other directly without any interposed guide components.

2. The device as claimed in claim 1, wherein at least one further width change assembly, which changes an initial spacing (a) of two adjacent fibers of the fiber strip to a target spacing (b) of adjacent fibers of the fiber strip, the ratio between the target spacing (b) and the initial spacing (a) for all the pairs of adjacent fibers matching within a tolerance band of 20%.

3. The device as claimed in claim 1, wherein the at least one width change assembly has an edge stop for defined guidance of all the edges of the fiber strip.

4. The device as claimed in claim 1, wherein the fiber strip is passed through a portion of an inner circumference of at least one of the guide contours.

5. The device as claimed in claim 1, wherein the fiber strip is passed over a portion of an outer circumference of at least one of the guide contours.

6. The device as claimed in claim 1, wherein the device has a top and a bottom, and wherein the fiber strip is guided between components located at the top and components located at the bottom, wherein at least some of the components located at the top have an operating position and a release position, in which the fiber strip is accessible from above.

7. The device as claimed in claim 1, comprising a heating unit for heating the fiber strip before entry into the at least one width change assembly.

8. A system comprising a plurality of devices as claimed in claim 1 to produce a combined overall fiber strip made of a plurality of fiber strips arranged beside one another.

9. The system as claimed in claim 8, wherein at least sections of the devices transport the fiber strips on different working planes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows, in a perspective view, a device for the twist-free width change, namely for spreading a fiber strip made of continuous fibers passing through to a predefined useful width;

(2) FIG. 2 shows an illustration similar to FIG. 1 of a further embodiment of a width change device for joining continuous fibers of a fiber strip together;

(3) FIG. 3 shows, in an illustration similar to in FIG. 1, a further embodiment of a width change device for spreading a fiber strip passing through, the fiber strip in the meantime being spread apart more highly than after the complete passage through the width change device; and

(4) FIG. 4 shows a system comprising a plurality of width change devices of the type according to FIG. 1, arranged beside one another, for producing a combined overall fiber strip made of a plurality of fiber strips arranged beside one another, which are spread apart beside one another by the width change devices of the system according to FIG. 4.

(5) A width change device 1 is used for the twist-free width change of a fiber strip 2 made of continuous fibers 3 passing through the device to a predefined useful width B. The fiber strip 2 runs into the device 1 with an initial width A. The fiber strip 2 is fed to the device 1 with the aid of a transport unit 4, illustrated extremely schematically in FIG. 1, which unit can be, for example, a pair of transport belts and/or transport rolls rotating in opposite directions.

(6) The device 1 has a width change assembly 5. This is designed in such a way that it changes an initial spacing a of two adjacent fibers 3 of the fiber strip 2 to a target spacing b of adjacent fibers 3 of the fiber strip 2. The ratio b/a between the target spacing b and the initial spacing a matches for all the pairs of adjacent fibers 3 of the fiber strip 2, within a tolerance band of 20%.

(7) The fiber strip 2 can be a yarn or a roving. The fiber material used for the fiber strip 2 can be glass fibers, carbon fibers, aramid, basalt, quartz fibers, boron fibers, synthetic fibers, polyester or natural fibers. Other fiber materials can also be used if non-rotated, parallel fibers are present. The number of individual continuous fibers 3 of the fiber strip 2 is illustrated in a highly understated manner in the drawing. In actual fact, several thousand individual fibers 3 may be present in the fiber strip 2, for example several tens of thousands, for example 50,000, individual fibers 3. If use is made of fiber strips with glass fibers, these can have, for example, 1000 to 10,000 individual fibers, for example 2400 or 4800 individual fibers. The fiber strip 2 to be processed in the device 1 can be a dry fiber strip, that is to say one not yet impregnated, or alternatively a wet fiber strip, that is to say one already impregnated in a preparation step.

(8) The width change assembly 5 comprises a first partially circular guide contour 6 having a first contour radius R.sub.1. The first guide contour 6 is located in an arrangement plane yz perpendicular to a transport direction x of the fiber strip 2. The coordinates x, y, z span a Cartesian coordinate system in FIG. 1.

(9) The width change assembly 5 further includes a second partially circular guide contour 7 having a second contour radius R.sub.2, which is located in a further arrangement plane yz perpendicular to the transport direction x of the fiber strip 2.

(10) The first guide contour 6 is implemented as a circular passage opening in a guide body 8, which is mounted so as to be clamped between two mounting blocks 9 on a base plate 10 of the width change device 1. The overall circularly designed first guide contour 6 is used only in a partial circular section, illustrated at the top in FIG. 1, in an inner circumferential region covering approximately 60. The first guide contour 6 is therefore used on a partial inner circumference.

(11) The second guide contour 7 is formed as the outer circumference of a circular guide disk, which is likewise used in an upper partial circular section over a circumferential angle of about 60. The guide contour 7 is therefore used on a partial outer circumference. The guide disk 7 has an axial positioning pin 11, which extends coaxially with respect to an axis of rotational symmetry of the guide disk 7 and, on both sides, projects beyond a disk plane of the guide disk 7. These projecting ends of the positioning pin 11 go into recesses complementary thereto in mounting blocks 12, between which guide disk 7 is clamped. The mounting blocks 12 are in turn mounted on the base plate 10.

(12) The two guide contours 6, 7 are arranged coaxially with respect to each other, the axis of rotational symmetry of the two guide contours 6, 7 coinciding and extending parallel to the x axis, that is to say parallel to the transport direction of the fiber strip 2 before the width change assembly 5.

(13) The fiber strip 2 is guided over the two guide contours 6, 7 such that the individual fibers 3 rest on both guide contours 6, 7. The two guide contours 6, 7 follow each other directly in the conveying path of the fibers 3 without any interposed guide components for the fibers 3.

(14) After being joined together, the fiber strip 2 can have a width B of, for example, 10 mm to 15 mm. Such a width, for example in the range between 12 mm and 13 mm, is suitable in particular for winding up the fiber strip 2 on conventional cross-wound spools.

(15) It can be shown that the ratio b/a and therefore also the ratio B/A corresponds to the ratio R.sub.2/R.sub.1. The width change device 1 according to FIG. 1 is used to spread out the fiber strip 2. In the width change device 1 used for the spreading, it is therefore true that A<B and a<b.

(16) In the guide path of the fiber strip 2 before the first guide contour 6, the fiber strip 2 runs over an inlet guide rod 13 located at the bottom for the predefinition of an inlet transport plane parallel to the xy plane. The inlet guide rod 13 is fixed between two mounting cheeks 14 which, for their part, are mounted on the base plate 10.

(17) In the transport path after the second guide contour 7, the spread-out fiber strip 2 runs under an outlet guide rod 15, via which a defined outlet plane for the spread-out fiber strip 2 is predefined, once more extending parallel to the xy plane. The outlet guide rod 15 is once more fixed between two mounting cheeks 16, which, for their part, are mounted in the base plate 10. The mounting cheeks 16 can be used at the same time as edge stops for the defined guidance of the lateral edges of the outgoing fiber strip 2.

(18) The guide rods 13, 15 extend parallel to the y direction.

(19) If the fiber strip 2 is guided between components located at the top and at the bottom, the components respectively located at the top can be displaced between an operating position and a release position. In the width change device 1, the components located at the top in this respect are firstly the used circumferential section of the first guide contour 6 and secondly the outlet guide rod 15 located at the top. The associated supporting elements of these components can be divided in a dividing plane 17, as indicated dashed in FIG. 1 in the region of the guide body 8, on the one hand, and the mounting cheeks 16, on the other hand. Via a division of this type and an appropriately designed articulated connection, firstly the guide body 8 and secondly the guide rod 15 can be pivoted between the operating position shown in FIG. 1 and a release position, the fiber strip 2 respectively being accessible from above in the release position of the two components 8 and 15 located at the top, which can be used to set up the width change device 1 or else for mounting and adjustment purposes.

(20) An inlet working plane in the conveying path of the fiber strip 2 before the guide rod 13 and an outlet conveying plane of the fiber strip 2 in the conveying path after the outlet guide rod 15 can coincide. Alternatively, these two working planes can also be spaced apart from each other, so that the fiber strip 2 is transported on different working planes in different sections of its conveying path in the region of the width change device 1.

(21) By using FIG. 2, a further embodiment of a width change device 18 will be explained below. Components which correspond to those which have already been explained above with reference to the embodiment according to FIG. 1 bear the same reference numbers and will not be discussed in detail again.

(22) The width change device 18 is used to join an incoming fiber strip 2 together. Here, it is therefore true that: A>B and a>b.

(23) In the width change device 18, the inlet guide rod 13 is implemented at the top in relation to fiber strip 2, and the outlet conveying rod 15 is implemented at the bottom in relation to the fiber strip 2. The first partially circular guide contour 6 is implemented as a guide disk of the type of the guide disk 7 of the embodiment according to FIG. 1. The first guide contour 6 in the width change device 18 in turn has a first contour radius R.sub.2.

(24) The second partially circular guide contour 7 in the width change device 18 is implemented as a passage opening with internal contour radius R.sub.3, corresponding to the guide contour 6 of the width change device 1.

(25) A contour radius R.sub.3 of the second guide contour 7 of the width change device 18 is greater than the contour radius R.sub.1 of the first guide contour 6 of the width change device 1 according to FIG. 1.

(26) The contour radius R.sub.2 of the first guide contour 6 according to FIG. 2 is exactly as large as the contour radius R.sub.2 of the guide contour 7 according to FIG. 1.

(27) Here, it is accordingly true that B/A=b/a=R.sub.3/R.sub.2.

(28) It is also true that R.sub.3/R.sub.2>R.sub.1/R.sub.2.

(29) Apart from the different ratio R.sub.3/R.sub.2 as compared with R.sub.1/R.sub.2, the width change device 18 can be understood as an inversion of the width change device 1. It is therefore readily possible to use the width change device 1 as a joining device, in which the transport direction +x of the fiber strip 2 is simply inverted (x) by the width change device 1. The fiber rod 15 then becomes the inlet fiber rod. The guide contour 7 then becomes the first guide contour. The guide contour 6 then becomes the second guide contour. The guide rod 13 then becomes the outlet guide rod. In an entirely corresponding way, width change device 18 can also be used to spread the fiber strip 2 by inverting the transport direction for the fiber strip 2. The outlet guide rod 15 then becomes the inlet guide rod. The guide contour 7 then becomes the first guide contour. The guide contour 6 then becomes the second guide contour, and the guide rod 13 then becomes the outlet guide rod.

(30) FIG. 3 shows a further embodiment of a width change device 19. Components which correspond to those which have already been explained above with reference to the embodiment according to FIGS. 1 and 2 bear the same reference numbers and will not be discussed in detail again.

(31) The width change device 19 constitutes a series connection of the width change devices 1 and 18. An outlet guide rod 20 of the width change device 1 is simultaneously the inlet guide rod for the following width change assembly 5 corresponding to the width change device 18. This guide rod will also be designated as an intermediate guide rod 20 below. The incoming fiber strip 2 is firstly spread out in the ratio R.sub.2/R.sub.1 in the width change device 19 and then joined together in the ratio R.sub.2/R.sub.3. This results in a net spreading in the ratio R.sub.3/R.sub.2.

(32) In the region of the intermediate guide rod 20, the fiber strip 2 is therefore present in an even more highly spread form than in the region of the outlet guide rod 15 after the second width change assembly 5 of the type of the width change device 18. This maximum spreading of the fiber strip 2 in the region of the intermediate guide rod 20 can be used, for example, for an intermediate treatment of the fibers 3 of the fiber strip 2.

(33) This spreading to an initially greater width can also be used to detach an adhesion of the incoming individual fibers 3, that is to say to open the incoming fiber strip. A defined subsequent impregnation of the outgoing fiber strip can then be ensured, an impregnating material obtaining access to all the individual fibers.

(34) FIG. 4 shows a fiber strip joining system 21. This has a plurality of width change devices for spreading out individual fiber strips 2 of the type of the width change device 1, which are arranged beside one another, that is to say offset in relation to one another in the y direction. The system 21 is used to produce a combined overall fiber strip 22 from the spread-out individual fiber strips 2 arranged beside one another.

(35) A first overall guide contour 23 of the system 21 is formed from an appropriate multiplicity of first partially circular inner guide contours 6 of the type of the width change device 1 that are located beside one another. FIG. 4 illustrates only a used upper and inner circumferential section of the guide contours 6 located beside one another. A second overall guide contour 24 of the system 1 is formed from a multiplicity of partially circular outer circumferential guide contours, which in turn are located arranged beside one another in a corresponding multiplicity. Differing, for example, from the second guide contour 7 of the width change device 1, the individual partially circular guide contours 25 of the second overall guide contour 24 are not part of an overall guide disk but constitute upper partially circular contour sections of otherwise cuboidal contour carriers 26. The contour carriers 26 are firmly connected to one another in a manner comparable with a carrying body 27 of the first overall guide contour 23, and can, for example, be implemented as a one-piece overall body.

(36) In the system 21, for the ratio R.sub.5/R.sub.4 of the radii, as compared with the ratio R.sub.2/R.sub.1 of the radii of the width change device 1 according to FIG. 1, it is true that:
R.sub.5/R.sub.4>>R.sub.2/R.sub.1,

(37) Because of this highly different ratio of the radii, the result is that an inlet working plane which is predefined by a position of the inlet guide rod 13 of the system 21 is located lower down in the z direction, that is to say is spaced apart from an outlet guide plane which is predefined by the position of the outlet guide rod 15 of the system 21. The incoming fiber strips 2 are therefore transported on a different working plane than the outgoing overall fiber strip. This can be used, for example, in an overall treatment process, for example during roving production, to carry out treatment steps at levels arranged one above another and thus in a space-saving manner.

(38) The overall fiber strip 22 can have an overall width of several hundred millimeters in the y direction.

(39) Overall, in the system 21 according to FIG. 4, ten individual fiber strips 2 are joined together to form the overall fiber strip 22. Depending on the design of the system 21, the number of individual fiber strips 2 that are joined together can be different and can, for example, move in the range between 2 and 50.

(40) The overall fiber strip 22 spread out in this way can be used as a precursor in the production of a fiber composite material in the form of an overall fiber strip impregnated with a polymer, which is also designated as a tape. Examples relating to the processing of such a fiber composite are specified, for example, in EP 2 521 640 A1.

(41) The width changes of the individual fiber strips 2 explained above are produced without any twist, that is to say without twisting the individual continuous fibers 3.

(42) The aim of the spreading is the production of a unidirectional surface structure (i.e. of the fiber strip with a weight per unit area that is defined and formed as uniformly as possible). The fiber strips 2 and 22 provided with the aid of the width change devices 1, 18, 19 described or with the system 21 can subsequently be impregnated, for example, with a thermoplastic polymer melt or with a reactive resin mixture and, after that, used further as in particular unidirectional pre-pregs or tape. The fiber strip produced can alternatively also be stored temporarily as fiber strip from a spool and further processed later. The fiber strip that is stored temporarily, that is to say for example wound up, can be a dry fiber strip or else one that is already impregnated, that is, wet. A corresponding fiber strip can be used in a device for producing multiaxial fiber fabrics. One example of this is multiaxial knitted fabrics.

(43) Before the entry of the fiber strip, for example in the region of the transport unit 4 illustrated before the inlet conveying rod 13 in FIG. 1, a heating unit for heating incoming fiber strip 2 can be provided. The heating unit can heat the fiber strip 2 via hot air, via IR radiation or via contact heat. When conductive materials are used, the heating can also be done by introducing current, in particular direct current, through the fibers 3 of the fiber strip 2.