Abstract:
A hemmer intended for making double-folded hems by feeding a fabric edge through the device comprising at least a folding edge, a main bar and a folding rule arranged at a distance above the main bar. The main bar front end being bevelled and designed to fold the fabric edge around the folding rule with the hem edge located between the main bar and the folding bar and in its second, rear part the main bar being designed with an upfolded, longitudinal edge section which partly is arranged to extend along and over the rear longitudinal edge of the folding bar and partly is bevelled at its front section. The hemmer in one embodiment may be adjusted to fold hems of different widths and hems which already have transverse hems.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a hemmer for providing double folded hems by feeding a fabric edge through the apparatus. 
     2. Description of the Prior Art 
     A hemmer of the above mentioned type is normally designed as a helical, taper sleeve, which by itself produces an acceptable double-folded hem, but which can be used for only one hem width and for fabrics having a specific thickness. Further, it is not possible to sew a hem across an existing hem. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a hemmer, which may be easily changed so that hems of different widths can be sewed. A further object is to provide a simple and relatively cheap device which has a good reliability in operation and which treats the fabric softly. A third purpose is to make it possible to sew fabrics which already are provided with transversel hems. These objects have been achieved by the invention which includes at least two folding rails a main bar and a folding rule arranged at a distance above the main bar. The mainbar rail is in its front end bevelled and designed to fold the fabric edge around the folding rule with the hem edge located between the folding bars. The second, rear part of the mainbar is designed with an upfolded, longitudinal edge section which partly is arranged to extend along and over the rear longitudinal edge of the folding rule and partly is bevelled at its front section. 
    
    
     The invention will now be described in greater detail with reference to the accompanying drawings wherein: 
     FIG. 1 is a top plan view of the hemmer according to the invention; 
     FIG. 2 is a top plan view of the main bar included in the hemmer according to FIG. 1; 
     FIG. 3 is a side elevational view of the main bar according to FIG. 2; 
     FIG. 4 is a cross-sectional view taken along line IV--IV in FIG. 2; 
     FIG. 5 is a top plan view of a folding rule which is included in the hemmer according to FIG. 1; 
     FIG. 6 is an elevational view of the folding rule according to FIG. 5; 
     FIG. 7 an enlarged cross-sectional view taken along line VII--VII in FIG. 5; 
     FIG. 8 is a top plan view of an edge rail included in the hemmer according to FIG. 1; 
     FIG. 9 is a side elevational view of the edge rail of FIG. 8; 
     FIG. 10 is a cross-sectional view taken along line X--X in FIG. 8; 
     FIG. 11 is a top plan view of the hemmer without a protection rail and with inserted fabric edge during different folding phases; 
     FIGS. 12-15 are cross-sectional views taken along lines XII--XII, XIII--XIII, XIV--XIV and XV--XV, respectively of FIG. 11 showing the fabric edge in different folding phases; and 
     FIG. 16 is a cross-sectional view through a modified hemmer according to the invention. 
    
    
     DETAILED DESCRIPTION 
     The hemmer 10 consists essentially of four parts, a main bar 11, a folding rule 12, an edge bar 13 and a protection rail 14. Since the last mentioned device mainly only has a protective function it will henceforth be omitted in the disclosure of the hemmer. 
     The main bar 11 consists of a plate profile which has an L-formed cross section; the rib planar part 15 of which is arranged essentially horizontally and the front end of which is bevelled. This bevelled end 16 extends to a straight tip 17 located at the flange 18 of the main bar. The rear section 19 of the main bar 11 is along the edge which is remote from the flange 18, provided with an upfolded longitudinal edge section 20, which in its front section is provided with a bevelled part 21, which provides a gradual passage from the front edge 22 of the main bar. The rear section 19 of the main bar is in some degree slightly bent upwards in the front of the bevelled part 21. As can be seen in FIG. 4 the upfolded longitudinal edge section 20 has an arch in its cross section. 
     To the flange 18 there is connected a bracket 23 by means of which the hemmer may be connected to a frame, i.e. a machine (not shown). At the horizontal part 15 of the main bar are arranged holes 24 and 25 intended for mounting of folding rule 12 and edge bar 13 respectively. 
     The folding rule 12 has essentially the same length as the main bar 11 and is arranged at some distance above it. By means of an attachment 26, which forms an extension of a vertical flange 27 of the folding rule which in cross section is essentially L-formed, the folding rule is detachably connectable to the underside of the main bar 11. The horizontal section 28 of the folding rule 12, is at its front end bevelled in such a way that the bevelled part 29 is facing the bevelled part 16 of the main bar. The folding edge 30 of the folding rule 12, which is remote from the flange 27, extends uninterrupted to the rear end of the rule. The rear section 20 of the rule is at the middle of the upfolded edge section 20 of the main bar designed somewhat narrower than the section 28 and its width is determining for the width of the hem. The rear section 21 is in the same manner as the rear section 19 of the main bar bent somewhat upwards. In the mounted condition of the main bar and the folding rule 12 the rear section 31 of the folding rule will partly be located below the upfolded end section 20 of the main bar. The clamp-like attachment 26 is designed and mounted to the underside of the main bar in such a way, that the section 28 is located at some distance from and parallel to the horizontal section 15 of the main bar. The holes 32 located in the attachment 26 correspond to the holes 24 located in the main bar. 
     The edge bar 13 is in its mounted position located close to the folding edge 30 of the folding rule 12 and has for this purpose essentially the same length. The edge bar has a curved cross section and is provided with two attachments 33, which are provided with oblong holes 34, corresponding to the holes 25 in the main bar 11. The front section 35 of the edge rail 13 is bent slightly upwards, as can be seen in FIG. 9 and its rear end section 36 has essentially the same angled position as the rear section 31 of the folding ruler and the rear section 19 of the main bar. The attachment 33 is mounted to the horizontal section 15 of the main bar by means of screws 37 and knob-like nuts 38. 
     THE FUNCTION OF THE HEMMER 
     Parallel to the hemmer 10 two endless conveyor belts 39 and 40 are arranged, of which only two belt sections contacting each other are shown (see FIG. 11). A fabric edge 41, which is intended to be provided with a hem, is transported between the belts 39 and 40 towards the hemmer and before arrives it will pass through a cutting device (not shown), where the fabric edge 42 is cut clean. 
     The front sections of the main bar 11, the folding rule 12 and the edge bar 13 are formed in such a way that when the fabric edge 41 is fed into the hemmer 10, it will be located above the folding rule 12, but below the edge bar 13 and the main bar 11, as is shown in FIG. 12. At a continued feed from position I in FIG. 11 to the position II the fabric edge will be folded over the folding edge 30 of the folding rule 12, in such a way that a part of the fabric edge will be located below the folding rule 12, as is shown in FIG. 13. The edge section 13 supports the outer surface of the fold at the same time so that the folding is done as exactly as possible. 
     When the fabric edge 41 has reached the position III in FIG. 11, the folding rule 12 continues in the more narrow rear section 31, at the same time as the main bar 11 supports the entire folded fabric edge. If the belts 39 and 40 continue to transport the fabric edge in the direction of the arrow 43 the outermost edge section 44 of the fabric edge 41 will be folded upwards on the folding rule 12, by the rear section of the main bar which continues in the upfolded longitudinal edge section 20 as is shown in FIG. 15. The upfolding of the edge section 44 of the fabric edge is possible, since the fabric between the belts 39 and 40 and the hemmer 10 is kept at a distance through the edge section 20. 
     The hem shaping is thereby finished and the conveyor belts 39 and 40 transport the folded hem to a sewing machine (not shown) arranged in direct connection to the hemmer. 
     In case a narrower or wider hem is desired the folding rule 12 only need be removed and replaced by one with the desired width b at the rear section 31. The edge bar 13 may, because of the oblong holes 34, be adjusted in a way so that it will be located in an exact position in relation to the folding edge 30 of the folding rule. 
     A great problem has until now been connected to the hemming of fabric pieces, which already are provided with a transversal hem, since by their thickness are very difficult and in many cases impossible to press through conventional hemmers. The modified embodiment in FIG. 16 shows a simple design of the above disclosed hemmer which may be adapted to sudden changes in thicknes of the fabric edge. The clamp shaped attachment 26 of the folding ruler 12 is designed with somewhat larger distance to the horizontal section 28 of the rule. The main bar 11 is provided with control pins 45 at the underside, said pins passing through corresponding holes in the attachment 26, and said pins 45 control the upward and downward motions of the folding rule. The outer ends of the control pins 45 are threaded and provided with nuts 46 and at every control pin a compression spring 47 is arranged between the main bar and the clamp-shaped attachment 26. 
     In a similar way as the folding rule 12 is vertically movable the edge bar 13 is horizontally movable against the action of a spring 48 on the underside of the main bar 11. 
     If a fabric edge which earlier has been provided with a hem is being fed into the hemmer according to FIG. 16 the folding rule 12 is flexibly moving as much as required to allow the thicker section to pass between the horizontal section 15 of the main bar and the corresponding section 28 of the folding rule. In the same way the edge bar 13 may be moved in the direction away from the folding rule in such a way that space for the passage of the hem is provided. The invention is not limited to the shown and disclosed embodiments but a number of embodiments are possible within the scope of the claims.