A DEVICE FOR FOLDING AN EDGE OF A FABRIC FOR MAKING A HEM

Abstract: A device for folding an edge of a fabric for making a single or a double hem comprising a pair of cooperating endless, driven bands (16, 30; 50, 70) for conveying the fabric edge through the device, at least one of said bands being twisted in correspon­ dance with the gradual folding of the fabric edge and is arranged to cooperate with at least one fixed ruler (15, 39; 12, 51) arranged in direct connection with at least a part of the band portions (30; 50). At least one of said bands (30; 70) is arranged to cooperate with means (41; 71, 72) for temporary speed variation of one of said bands (30; 70) relative to the other band (16; 50) in order to provide that the hem edge will be located somewhat inside the fabric edge extending transversely to the hem.

Description: The present invention refers to a device for folding an edge of a fabric for making a single or a double hem comprising a pair of cooperating endless, driven bands for conveying the fabric edge through the device, at least one of said bands being twisted in correspondance with the gradual folding of the fabric edge and is arranged to cooperate with at least one fixed rule arranged in direct connection with at least a part of the band portions. Background of the invention Hem shaping means are known in a plurality of different embodiments. The most common means consists of a helical, conical sleeve through which the fabric edge is passed at the same time as the folding takes place. There is also previously known a hem shaping means consisting of two folding bars provided with upwards directed portions between which and the bars the folding takes place. Fixed bars, however, involve that the space that once has been chosen between the bars for a safe folding and transport of the fabric edge through the folding device can not be instantaneously changed in order to let a transverse seam with a considerably larger thickness than the actual fabrics with transverse hems can not or only with difficulty be sewn in such hem-shaping means, which is an obvious drawback. In EP-A-0 158 614 there is shown a device of the kind mentioned above, viz. in which the hem shaping means comprises portions of an endless, driven band, which is twisted along a rule for the gradual folding of the fabric during transport thereof through the device. This device is insensitive to variations of the thickness of the fabric and also transverse seams with a considerable thickness can pass without difficulty. The present invention is intended as a further developement of this previously known device. It is desired e.g. when hemming towels and sheets, that the end edges of the transverse hems are not located outside the longitudinal fabric edge, but rather be drawn in somewhat inside this. This is normally no problem at the feed end of the hem, but at the feeding-out end the hem has easily a tendency to be drawn out slightly outside the fabric edge. Object and most important features of the invention The object of the present invention is to provide a folding device, which in a simple way solves this problem and accomplishes that the hem edge will be located level with or just inside the fabric edge extending across the hem. This object has been solved by the fact that at least one of said bands is arranged to cooperate with means for temporary speed variation of one of said bands relative to the other band. Description of the drawings The invention will now be closer described with reference to a couple of embodiments shown in the accompanying drawings. Fig. 1 shows the folding device according to the invention in a side view. Fig. 2 shows in perspective endless bands and rules contained in the folding device. Fig. 3 is a section according to the line III-III in fig. 1. Fig. 4 shows in section and on a larger scale a band stretching device contained in the folding device. Fig. 5 shows in side view a modified embodiment of the folding device according to the invention. Fig. 6 shows in section and on a larger scale a band stretching device contained in the folding device for adjusting the relative speeds of the bands. Fig. 7 is a section according to the line VII-VII in fig. 5. Description of embodiments The folding device according to the invention corresponds largely to the one disclosed in EP-A-0 158 614, which comprises a feed table 11 on the table top 12 of which the fabric 13, which is to be provided with a fold is transported. The transport takes place by means of an endless band 14, which feeds the fabric in the longitudal direction of the table. At one side edge of a table a vertical rail 15 making one first folding rule of the folding device is arranged. Outside the rule 15 there is arranged a first endless transport band 16, along which a first shaping section 17 is arranged essentially vertically and substantially parallel to and in contact with the rule 15. A number of guide rolls 18-21 and a pulley roll keep the band part in question in position. The endless band 16 is by way of the pulley rolls 23, 24, the drive roll 25, the stretching roll 26 and the pulley rolls 27 and 28 driven in the direction of the arrow 29. A second endless band 30 is arranged opposite the rule 15 and cooperating with this, said band at the beginning of the first shaping section 17 has a substantial horizontal position and is gradually towards the pulley roll 22 twisted to vertical position. The band 30 extends from the pulley roll 22 further to the pulley rolls 31 and 32, to the drive roll 33 and by way of a stretching roll 34 to the pulley roll 35, and returns after that to the pulley roll 22. The twisting of the second band part 30 from horizontal position at the guide roll 18 to vertical position at the pulley roll 22 is supported and guided by the support rolls 36 and 37. The first band 16 continues from the press nip between the rolls 21 and 22 from vertical position to horizontal position at the pulley roll 24, and during this twisting movement, i.e. a second shaping section 38, the band part in question will be brought to contact against a second rule 39. This is also twisted in the corresponding way as the band section in question and this rule is in the same way as the rule 15 fixed to the table top 12. All the rolls supporting and driving the two endless bands are mounted in a frame 40. A band stretching device 41 is arranged to cooperate with the band 30 shortly after the stretching roll 34. The band stretching device consists of two rolls 42 and 43 mounted in a plate 44, which in turn is rotably mounted in the frame 40. A change of the rotational position of the plate 44 is provided by means of an actuator 45, at which the band 30 is stretched or slackened. By stretching the band 30 its speed is increased and in a corresponding way the speed of the band 30 is reduced by slackening it. The folding device according to the invention functions in the following way. The two bands 16 and 30, which are driven by a common motor (not shown) are displaced in the direction of the arrow 29, i.e. at the shaping sections 17 and 38 in the same direction as the transport band 14. A fabric 13 which is clamped between the band part 14 and the table 12 will thus be displaced along the entire folding device. The fabric 13 is then guided into the folding device, so that the edge 13a will hang over the table edge 12, as is shown in figure 3. The overhanging fabric edge is guided in between the rule 15 and the first band part 16. The projecting end portion of the fabric edge will by that come to contact with the second band part 30, which at the entrance of the fabric edge in the folding device takes a substantial horizontal position. Concurrently with the displacement of the fabric edge through the folding device the end portion will be folded up more and more against the inside of the rule 15 by means of the second band part 30, which is twisted from horizontal position to vertical position. The vertical portion of the first band part 16 helps to transport the fabricedge on the outer side of the rule 15. At the section III-III in figure 1 and 2 the fabric edge has been folded in U-shape about the rule 15 and the two shanks of the U are fixed by a band part 16 and 30 each. The fabric edge will then leave its engagement with the band part 30 and the end portion 13a of the fabric edge has been brought into contact with a second rule 39 of the folding device extending from the pulley roll 22 vertically to horizontal position at the pulley roll 24. The fabric edge will in cooperation with the first band part 16 be gradually folded in the second shaping section 38 in the direction towards the table top 12, so that when the fabric edge leaves the pulley roll 24 a double folded hem has been provided. By temporarily increasing the speed of the band 30 relative to the band 16 at the end of the feeding of the hem through the folding device the rear end edge of the hem will be drawn slightly forwards with respect to the rest of the fabric, at which the hem edge will be located slightly inside the fabric edge extending transversely to the hem. In direct connection to the pulley roll 24 there is arranged a connection approach 46 to a sewing machine, where the hem is sewn. In order to permit also very thick material portions in the form of transverse seams get past the guide rolls 18, 19, 20 and 21, these are spring-loaded and can thus spring aside if the material thickness suddenly is increased. The embodiment according to figure 5 differs from the previous embodiments by the fact that the shaping means comprises one single endless, driven band 50 cooperating with a shaping rule 51, which is fixed to the feed table 11. The endless band 50 is driven by a drive roll 52. The band 50 extends from the drive roll 52 by way of the pulley rolls 53, 54 and 55 to a position in which the band is located on a level with the table top 12 of the feed table 11. The band portion 50a between the roll 55 and a roll 56 is twisted 180° so that the band portion during a substantial part of its length will be in contact with the correspondingly shaped shaping rule 51. The roll 56 is spring-loaded so that it is given a contact pressure against the table top 12. From the roll 56 the band continues with a straight portion via a further spring-loaded roll 57 to a roll pair 58, 59 of which the first roll 58 is pivotable about the axle of the second roll 59, to which also a spring is attached, and from there 360° back in a straight portion 50c parallel to the portion 50b to the roll 56 and from there in 180° twisting to a roll 60 located at a somewhat lower level as compared to the roll 54. The band part 50b follows during a portion of its length the twisting of the band part 50a. The band 50 continues from the roll 61 to the pulley rolls 61, 62, 63 and 64 and then further as a band part 50e in 180° twisting to a second roll pair 65, 66, which in the same way as the first roll pair 58, 59 consists of a stationary roll 65 and a roll 66 which with respect to this is pivotable and spring-loaded. This roll 66 presses a portion of the band part 50e to contact against the table top 12. The band continues as the band part 50f from the roll pair 65, 66 with 180° twisting to the pulley roll 67 and then back to the drive roll 52. A second endless band 70 extends about two drive rolls 71 and 72 and via two pulley rolls 73 and 74 to a position in parallel with the band portion 50b. The band 70 turns off from the first band via a pulley roll 75 arranged between the spring-loaded rolls 56 and 57 and extends back to the drive roll 71 via a further pulley roll 76. The device functions in the following way: A piece of fabric 13, e.g. a sheet, which by appropriate transport means such as endless transport bands, not shown, is transported along the feed table 11 with the fabric edge which is tc be hemmed, contacting the side edge 12 of the feed table, will be inserted under the roll 66 of the first roll pair and gets its continued transport movement by the endless band 50 of the folding device in cooperation with the table top 12 and the shaping rule 51 respectively. The piece of fabric 13 is by the band portion 50e pressed against the table top 12, while the projecting portion of the piece of fabric 13 will hang freely downwards along the free longitudinal side edge of the table top. During the continued displacement along the feed table 11, 12 the projecting fabric edge 13a will by the 180° twisted band part 50d be turned to contact the underside of the table top 12. Just opposite the roll 64 in the table top 12 there is provided a recess 68 permitting the fabric edge 13a located on the underside of the table top to leave the table top as is shown in figure 7. The continued displacement of the piece of fabric through the folding device is now taken over by the band part 50b, which in cooperation with the band 70 transports the folded fabric edge along the shaping rule 51. It is then transported by the band part 50a along the shaping rule 51. Since the band part 50b from the roll 56 to the roll 54 is twisted 180° in the same way as the shaping rule 51, the once folded fabric edge 13a will be exerted to a further folding, so that a double folded hem is provided. Two drive wheels 71 and 72 are arranged for the second band 70, at which these drive wheels by means of built-in couplings can be switched from driving to off position. The drive wheels 71 and 72 cooperate with drive means operating at different speed, at which the speed of the band 70 will be changed when switching over between the two drive wheels 71 and 72. One of the drive wheels, e.g. 71, is intended to be driven at a speed corresponding to the speed at which the band 50 is driven, while the other drive wheel, e.g. 72, is intended to be driven at a somewhat higher speed. By temporarily switch in the wheel 72 as drive wheel at the same time as the wheel 71 is disconnected, at the end of the feeding of the hem through the folding device, the folded part 13a will be drawn somewhat in front of the rest of the piece of cloth 13, so that the hem edge will be located somewhat inside the fabric edge in the preferred way. A change of the band speed can of course also be achieved by switching over the drive wheel of the band between different driving speeds. An adjustment of the relative speeds of the bands 50 and 70 can be made by means of the device shown in fig. 6 and which corresponds to the wheel 71 in fig. 5. The wheel 71 comprises a rubber cylinder 72 clamped between two plates 73 and 74. The plate 73 can by means of a nut be tightened along the wheel axle 76 at which the rubber cylinder 72 is axially compressed, which causes this to belly, as shown with dashed lines in fig. 6. The band 70 will then be stretched, i.e. the band speed increases. This device is firstly intended for manual synchronization of the speeds of the bands 50 and 70. The invention is not limited to the embodiment shown but a plurality of variations are possible within the scope of the claims.

Claims: 1. A device for folding an edge of a fabric for making a single or a double hem comprising a pair of cooperating endless, driven bands (16, 30; 50, 70) for conveying the fabric edge through the device, at least one of said bands being twisted in correspondance with the gradual folding of the fabric edge and is arranged to cooperate with at least one fixed rule (15, 39; 12, 51) arranged in direct connection with at least a part of the band portions (30; 50), characterized in , that at least one of said bands (30; 70) is arranged to cooperate with means (41; 71, 72) for temporary speed variation of one of said bands (30; 70) relative to the other band (16; 50). 2. A device as claimed in claim 1, characterized in , that said means comprises a band stretching device (41), which by means of an actuator (45) is arranged to stretch or slacken the band (16) to some extent. 3. A device as claimed in claim 1, characterized in , that said means comprises a driving roll (71, 72) cooperating with at least one of the bands (70), said driving roll is driven by a motor with variable speed. 4. A device as claimed in claim 1, characterized in , that at least one of the bands (70) cooperates with two pulleys (71, 72) with a built-in coupling for switching from driving to off position, at which the pulleys (71, 72) are arranged to cooperate with a driving device each which are driven with different speed. 5. A device as claimed in any of the proceeding claims, characterized in , that at least one of the bands (70) is arranged to cooperate with a driving roll (71), the diameter of which is adjustable for stretching and slackening the band (70) and by that adjust the relative speeds of the bands (16, 30; 50, 70). 6. A device as claimed in claim 5, characterized in , that said driving roll (71) comprises a resilient cylinder (72) and means (73, 75) for compressing this in axial direction.

Inventors: BOLANDER, LARS
Applicants: AKAB OF SWEDEN AB
Application year: 1988
Main classification: D05B33
IPC codes: D05B35