Title of Invention

A HEATING APPARATUS FOR HEATING AN ADVANCING YARN

Abstract

ABSTRACT The present invention relates to heating apparatus for heating an advancing yam (7), comprising an elongate heater (1) with an axial groove (2), the groove having opposite side walls (4 5) mounting several yam guides (6) for guiding the yam (7) along a zigzag line in axial direction tiring groove (2) characterized in that the yam guides (6) are formed as elevations (6.1,6.2) on two metal strips (3.1, 3.2), and that the metal strips (3.1, 3.2) are supported in face-to-face relationship on side walls (4, S), witan opposite elevations (6.1,6.2) being offset from one another.

Full Text

BEATZHO APPARATUS FOA HEATZNO AH ADVAKCXKO XARH The invention relates to a heating apparatus for heating an advancing yarn with the characteristics as defined in the preamble of claim 1. In particular, for crimping synthetic filament yams in a false twist crimping machine, it is common to provide heaters, through which a yam is guided. The yam advances in a heatable axial groove, the target temperature of the yarn being in a range from 150"C to 230°C. The heater is operated at a temperature, which is substantially higher than SOCC. A heater may have several grooves each of which serves to guide one yam. Known from EP o 412 429 Bl is a heater, which has a heatable axial groove, through which the yarn advances along a zigzag line. The zigzag line is formed by several yarn guides, one yarn guide being arranged at each reversal point of the line. The yam guides are individual ridges, which are inserted into the axial groove parallel to and equally spaced apart from one another. It has shown that in operation the yarn guides soil after a certain period of time as a result of anorganic deposits. To avoid that the deviation of the yarn Guidance from a desired Value cxceasiveiy large, it is necessary to remove and clean the yarn guides. In the known heater, each yarn guide must be removed individually, which is time consuming. It is therefore the object of the present invention to further develop the known heater such that the number of yarn guide elements is minimized, meds the handling necessary for changing the yarn guides is simplified. This object Is accomplished by a heating apparatus having the characteristics of claim 1. The heating apparatus of the present invention is characterized in that the yarn guides are formed as elevations on two opposite metal strips. Since the elevations are arranged alternatingly on the one and on the other metal strip, and since the elevations project beyond the center plane of the groove, the yam is caused to advance along a zigzag line. The metal strips may be manufactured by hot or cold forming, so that the position and dimensions of the elevations are dependent on a mold or tool, and that they exhibit a very high accuracy among each another. As a result, the looping angles and the frictional conditions are equal at each deflection point of the yarn, which favors a smooth run of the yarn. The metal strips are supported on opposite side walls of the axial groove and positioned relative to each other such that opposite yearn guides are offset from one another. For cleaning the yarn guides, both metal strips may be simply pulled out of the axial groove and, subsequently, be reinserted- To ensure that the yarn assumes a uniformly smooth run over the entire heating length, the yarn guides are to be arranged in accordance with claim 2. The configuration of the heating apparatus in accordance with claim 3 is especially advantageous, when the yarn is to be heated very rapidly. To this end, the yam guides are arranged in a first section of the heating apparatus at a slight distance from each other, so that the air jacket carried along by the yarn can be stripped vigorously. In the further course of the heating length, the yam guides are further spaced apart from each other. The arrangement of the elevations on the metal strips may also be such that two successive elevations are formed alternatingly on the one and on the other metal strip. This measure allows to reduce the looping angle on each yarn guide advantageously by 50 percent. The configuration in accordance with claim 5 is of advantage because of the low manufacturing costs of the sheet metal strips. The corrugations may be formed by simple bending or stamping tools. For purposes of positioning opposite yarn guides, the metal strips are interconnected by means of several crosspieces. Advantageously, the crosspieces are arranged in the vicinity of the groove bottom, so as to avoid that the yarn comes into contact with the heated surface of the groove bottom. The embodiment of claim 7 is advantageous in that opposite yarn guides are formed on a shaped metal sheet, and that thereby the position of the yam guides relative to one another is defined exclusively by the bending or stamping tool. Furthermore, the arrangement of crosspieces between the sides may be omitted. The embodiment of claim 8 is a cost-favorable alternative for obtaining a shaped section from a flat metal strip. The incisions parallel to the fold line permit to form the corrugations down to the groove bottom in the folded condition. Furthermore, it is avoided that a corrugation extends into the fold line, which would strongly interfere with a subsequent forming process. The ends of the yarn guides on the yarn insertion side are realized in accordance with claim 9, preferably such that they are flattened toward the center plane of the groove. This results in a V-shaped or circular inlet in the axial direction, which permits a simple threading of the yarn. If the yarn guide is made in the form of a corrugation, same proceeds from the upper side of the axial groove with an increasing depth, the profile of the axial groove thereby resulting in a V-shaped opening toward the yam insertion side. The embodiments of claims 10 and 11 relate to an advantageous configuration of the yam guides in the side walls, which allows to obtain a favorable looping angle and a small surface of friction. The shaping of the yarn guides must be accurately predefined, since it has a substemtial influence on the rimming characteristics of the yarn. It has been found that yarns of certain polymer types, for example, polyamide, must have a high degree of contact with the yarn guides for their heat treatment. This treatment may advantageously be realized with a heating apparatus in accordance with claims 12 and 13. The configuration of claims 14 and 15 prevents the yarn from contacting the groove bottom and, thus, from being damaged as a result of thermal stress. Likewise in this instance, it will be again advantageous to bound the bottom corrugation by incisions parallel to the fold line, when the channel section is made from a flat sheet metal strip. To guarantee an adequately high resistance to wear, the metal strip may be provided on it inner side, at least in the region of the yarn guides, with a coating of a hard material. To this end, the metal strip or the channel section with the yarn guides formed thereon may be treated with nitride or boride. The coating is from 10 to 30 /im. Surface hardnesses from 1,000 HV to 2,000 HV are obtained. In applications, which require a protection against wear, it is preferred to use yarn guides with a chromium nitride or a titanium nitride coating. These relatively thin films from 6 to 9 /im are applied by the PVD or the CVD process. The surface hardness is in a range of ^ 3,500 HV. At this point, it should be noted that the heating apparatus of the present invention is not limited to the aforesaid types of coating. However, other commonly used types of coating may be applied likewise. The configuration of the heating apparatus in accordance with claims 19 and 20 has the advantage that several heating zones with a different yam guidance are formed, thus permitting additional optimizations of temperature and yarn quality. The heating zones of the heating apparatus may be flexibly combined in accordance with claim 21. Accordingly, the present invention provides a heating apparatus for heating an advancing yam, comprising an elongate heater with an axial groove, the groove having opposite side walls mounting several yam guides for guiding the yam along a zigzag line in axial direction through groove, characterized in that the yam guides are formed as elevations on two metal strips, and that the metal strips are supported in face>to-face relationship on side walls, with opposite elevations being offset from one another. hi the following the invention is described in more detail with reference to embodiments. With reference to the accompanying drawings, in which: Figure 1 shows a metal strip with yam guides formed thereon; Figure 2.1 is a schematic top view of a heating apparatus with two cormgated sheet metal strips; Figure 2.2 is a cross sectional view along line I-I of Figure 2.1; Figure 3.1 is a schematic top view of a heating apparatus with a cormgated profile; Figure 3.2 is a cross sectional view along line H-II of Figure 3.1; Figure 3.3 is a cross sectional view along line m-III of Figure 3.1; Figures 4.1 and 4.2 are each a schematic top view of a heating apparatus with a cormgated profile; Figure 3.1 shows an unfolded sheet metal strip with cormgations; Figure 5.2 shows a folded sheet metal strip (channel section) with cormgations; Figure 6 is a schematic top view of a heating apparatus with two successive channel sections; and Figgie 7 is a schematic top view of a heating apparatus with a corrugated channel section. A metal strip 3 comprises along its axial direction a plurality of yarn guides that are formed on its one side in the shape of elevations C.l. The elevations 6.1 have preferably a cross section in the shape of a divided circle or divided ellipsis, and they are equal-sized as can be noted from Figure 1. In the region of the yarn guidance, the elevations 6.1 are made cylindrical, so as to form a curved yarn guide surface 20. At one end of the yam guides or elevations 6.1 a bevel 10 is formed. The bevel 10 is inclined, so that it forms with the metal strip an acute angle. The bevel is located on the side from which the yarn is inserted. The metal strips 3 are shaped by means of cold or hot forming processes or by means of a machine cutting process from solid material. The width of metal strip 3, which results from the depth of elevation 6.1 and the thickness of the sheet metal, must be somewhat larger than half the width of an axial groove 2 that is formed in an heating apparatus 1. Shown in Figure 2.1 is a heating apparatus 1, which has an axial groove 2 arranged therein. Inserted into axial groove 2 are two metal strips 3.1 and 3.2. The metal strips 3.1 and 3.2 are supported on opposite side walls 4 and S of axial groove 2. In the Figure, the elevations 6.1 of metal strip 3.1 and the elevations 6.2 of metal strip 3.2 are formed as corrugations 21 and arranged In face- relationship offset froe one another, the depths of elevations 6.1 and the depth of elevations 6.2 extending beyond the center plane of the groove. The surfaces of the elevations form yarn guide surfaces 20. An inserted yam 7 is deflected on you guides 6 such that it forms a zigzag course. The metal strips 3.1 and 3.2 of Figures 2.1 and 2.2 are sheet metal strips with corrugations 21 formed therein by stamping. The two metal strips 3.1 and 3.2 are interconnected by means of crosspieces 8 in groove bottom 9, so as to savvier the metal strips 3.1 and 3.2 in their position relative to one another. The crosspieces 8 are arranged between the metal strips 3.1 and 3.2, preferably spaced apart from groove bottom 9, so as to prevent yam 7 from coming into contact with the groove bottom 9 of heating apparatus 1. As shown in Fig\ire 2.2, the metal strips 3.1 and 3.2 terminate with their elevations 6.1 and 6.2 in a bevel 10 on the yarn insertion side. The bevel 10 inclines toward the groove center, so as to form a V-shaped or a circular inlet 11 which facilitates the insertion of yeurn 7. The embodiment of Figxires 3.1 and 3.2 consists of a channel section or a shaped sheet metal strip 14, the yarn guides 6 being stamped in both sides of the uncial center in the form of corrugations 21. The corrugations on side walls 14.1 and 14.2 alternate from one side to the other and guide the yarn in a zigzag line along axial groove 2. The channel section 14 has a cross section which corresponds to the cross section of axial groove 2. The corrugations 21 euro shaped such that the depth of corrugation 21 increases from the upper side of axial groove 2 to its maximum depth that is necessary for guiding the yarn. This results, as can be noted from Figure 3.2, in a bevel 10 and, thus, in the formation of a V-shaped inlet 11, which facilitates likewise the insertion of the yarn. To keep the yam off the groove bottom, bottom corrugations 12 are provided by stamping between side walls 14.1 tend 14.2 of channel section 14. These bottom corrugations 12 extend transversely to the axial groove, as can be noted from Figure 3.3, and they have a cross section in the shape of a divided circle or divided ellipsis. However, other cross sections are possible. To keep the contact with the yarn as slight as possible, it will be advantageous to form the bottom corrugation higher at the start and at the end of the heating zone, so that there is barely a contact with the bottom corrugations in the remaining range of the heating zone. Shown in Figure 4.1 is a channel section with side walls 14.1 and 14.2, each of which is provided by stamping with two successive corrugations 21, which alternate from one side wall to the other. This arrangement of the yarn guides allows to accomplish that the looping of the yarn can be reduced by 50% with the same number of yarn guides as in the heating apparatus of Figure 3.1. Furthermore, in the heating apparatus of Figure 4.1, the spacing between oppositely adjacent yarns guides 6 is made smaller at the inlet end of the heating zone than in the remaining length of the heating zone. This results in an irregular zigzag course of the yarn. In particular in the inlet region, the short zigzag leads to a rapid heating of the yarn, since the air jacket curried along by the yarn is stripped several times in a rapid succession. In addition, the yarn is rapidly smoothed during its passage. Shown in Figure 4.2 is a heating apparatus with an arrangement of yarn guides, which permits at the beginning a small looping of the yarn on each yarn guide, so as to then change over to a regular zigzag course with alternate use of one yarn guide. Also in this embodiment, the—yarn guides are formed as stamped-in corrugations 2ir. Preferably, the channel section 14 is made from a flat sheet metal strip 15. To this end, as shown in Figure 5.1, the sheet metal strip 15 is folded along two lines 18 to a desired shape. The corrugations 21 and bottom corrugations 12 are previously shaped in the sheet metal strip 15 by meme of a bending stamp tool. To delimit the corrugations 21 and the bottom corrugations 12 relative to the fold line 18, incisions 16 and 17 are made before the shaping. In sheet metal strip 15, opposite to corrugations 21, inspection windows 24 are stamped out in each of the facing sidajyus. These inspection windows 24 permit a visual judgment of the degree of soiling on the yarn guides in the dismantled state. Furthermore, at the one end of the sheet metal strip a hole 25 is stamped out for applying a tool. Shown in Figgie 5.2 is the sheet metal strip 15 folded to a channel section. This channel section with corrugations 21 and 12 is inserted, as illustrated, without further modification, into an axial groove 2 of a heating apparatus 1. Shown in Figure 6 is a heating apparatus with channel sections 14 and 19 one following the other in the longitudinal direction of axial groove 2. The metal strips are formed in this embodiment by side walls 14.1, 14.2 and 19.1, 19.2 of channel sections 14 and 19, Provided by stamping in side walls 14.1 and 14.2 are corrugations 21.i and provided in side walls 19.1 and 19.2 are corrugations 21.2. All corrugations 21.1 and 21.2 have the same depth. The spacings between corrugations 21.1 on side walls 14.1 and 14.2 and the spacings between corrugations 21.2 and side walls 19.1 and 19.2 are uneven, so that the yarn is guided differently in the heating zones of channel sections 14 and 19. The heating apparatus of Figure 7 comprises again a channel section that is inserted in axial groove 2 with its side vails 14.1 and 14.2 being supported on side vails 4 and 5. In side walls 14.1 and 14.2, corrugations 22 axe provided by a forming process. The corrugations 22 have a rectangular cross section, and form a guide surface 23 on their longitudinal side. The corrugations 22 extend through the center plane of axial groove 2, so as to guide the yam 7 in a zigzag course along axial groove 2. In the region of corrugations 22, the yarn 7 is in contact with guide surface 23, so that there results a great length of contact. This heating apparatus permits the yarn to be heated by contact. The heating apparatus shown in Figures 2.1-6 are elongate rails. Arranged in the rail is an axial groove 2 with opposite side walls 4 and S. The axial groove 2 is heated by a resistance heater 13. Seune is constructed as a bar. This bar is inserted into a bore, which is axially arranged in the base plate of the heating apparatus. To avoid of heat, the axial groove 2 is closed in operation by a lid, after the yarn is inserted. KOMBHCIATURS 1 Heating apparatus 2 Axial groove 3 Carrier 3.1 Metal strip 3.2 Metal strip 4 Side wall 5 Side wall 6 Yarn guide 6.1 Elevation 6.2 Elevation 7 Yarn 8 Crosspieces 9 Heating surface, groove bottom 10 Bevel 11 Inlet 12 Bottom corrugation 13 Resistance heater 14 Channel section 14.1 Side wall 14.2 Side wall 15 Sheet metal strip 16 Incision 17 Incision 18 Fold line 19 Channel section 19.1 Side wall 19.2 Side wall 20 Guide surface 21 Corrugation 22 Corrugation 23 Guide surface 24 Inspection window 25 Hole WE CLAIM: 1. A heating apparatus for heating an advancing yarn (7), comprising an elongate heater (1) with an axial groove (2), the groove having opposite side walls (4, 5) mounting several yam guides (6) for guiding tile yam (7) along a zigzag line in axial direction groove (2), characterized in that the yam guides (6) are formed as elevations (6.1,6.2) on two metal strips (3.1, 3.2), and teat titer metal strips (3.1, 3.2) are supported in-fee-to-face relationship on side walls (4, 5), with opposite, elevations (6.1,6.2) being offset from one another. 2. The heating apparatus as claimed in claim 1, wherein the spacings between adjacent yam guides are equal in the axial direction. 3. The heating apparatus as claimed in claim 1, wherein the spacings between adjacent yam guides are unequal in the axial direction. 4. The heating apparatus as claimed in any one of claims 1-3, wherein the two metal strips (3.1, 3.2) are each provided with one or two yarn guides (6) formed thereon alternately in the axial direction. 5. The heating apparatus as claimed in any one of the preceding claims, wherein tile metal strip (3) is a sheet metal strip, and that tile yam guides (6) are formed thereon as corrugations, moldings, or impressions (21) of the sheet metal strip. 6. The heating apparatus as claimed in any one of claims 1-S, wherein the opposite metal strips (3.1, 3.2) are interconnected by crosspieces (8) arranged transversely to the axial groove (2). 7. The heating apparatus as claimed in any one claims 1-4, wherein the metal strips (3.1, 3.2) are shaped to form the side walls (14.1, 14.2) of a channel section (14), the cross section of which corresponds to the cross section of the axial groove (2). 8. The heating apparatus as claimed in claims 5 and 7, wherein the channel section (14) is shaped from a flat metal sheet (15), which is folded in accordance with the cross section of the axial groove (2), and in which each corrugation (21) has an incision (16) of metal sheet (15), which extends along, or at a small distance parallel to, the fold line (18). 9. The heating apparatus as claimed in any one of claims 1-8, wherein the yam guides (6) terminate on the opposite side of the groove bottom (9) in an oblique bevel (10), which inclines toward the center plane of the groove. 10. The heating apparatus as claimed in any one of claims 1-8, wherein in the region of the yam guidance, the yam guides (6) have a guide sulfate (20) that is curved in the plane of the advancing yam. 11. The heating apparatus as claimed in claim 10, wherein the yam guides (6) have a cross section in the shape of a divided circle or divided ellipsis. 12. The heating apparatus as claimed in any one of claims 1-8, wherein in tile region of the yam guidance, the yam guides (6) have a guide surface (22) extending substantially parallel to side walls (4, 5). 13. The heating apparatus as claimed in claim 12, wherein the yam guides (6) have a rectangular cross section. 14. The heating apparatus as claimed in claim 8, wherein the channel section (14) is provided in the groove bottom with several successively arranged corragations (12), each bottom corrugation (12) being bounded by two opposite, parallel incisions (17) provided in the metal sheet (13), and the incisions (17) extending along or slightly spaced apart from tile fold line (18). 15. The heating apparatus as claimed in claim 14, wherein the bottom corragations (12) have, a cross section in the shape of a divided circle or divided ellipsis and are made cylindrical in the transverse direction of axial groove (2). 16. The heating apparatus as claimed in any one of claims 1-13, wherein the metal strips (3.1, 3.2) are provided with a hard material coating on their inner side at least in the region of the yam guidance. 17. The heating apparatus as claimed in claim 16, wherein the metal strips (3.1, 3.2) are treated with nitride or boride on their inner side at least in the region of the yam guidance. 18. The heating apparatus as claimed in claim 16, wherein the metal strips (3.1, 3.2) are provided on their inner side, at least in the region of the yam guidance, with a chromium nitride or a titanium nitride coating. 19. The heating apparatus as claimed in any one of claims 1-18, wherein several metal strips (14.1,19.1) are arranged one behind the other in the longitudinal direction of axial groove (2). 20. The heating apparatus as claimed in claim 19, wherein the spacing between yam guides (6) on the successively extending metal strips (14.1, 19.1) is uneven in the axial direction. 21. The heating apparatus as claimed in claims 19 and 20, wherein the successively extending metal strips (14.1,19.1) have the same length. 22. A heating apparatus for heating an advancing yam, substantially as herein described with reference to the accompanying drawings.

Documents:

396-mas-1996 abstract.pdf

396-mas-1996 claims.pdf

396-mas-1996 correspondence-others.pdf

396-mas-1996 correspondence-po.pdf

396-mas-1996 description(complete).pdf

396-mas-1996 drawings.pdf

396-mas-1996 form-1.pdf

396-mas-1996 form-26.pdf

396-mas-1996 form-4.pdf

396-mas-1996 form-9.pdf

396-mas-1996 petition.pdf