GB1586901A - Sewing machines and components therefor - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO SEWING MACHINES AND COMPONENTS THEREFOR (71) We, PFAFF INDUSTRIEMASCHMEN GmbH., a German Company, of Konigstrasse 154, 6750 Kaiserslautern, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a presser foot for a sewing machine with a horizontal trimming device for trimming the edges of material which cooperates with the foot and with a base having a guide groove for the upturned material edges extending from its front end to behind the trimming station.

Known presser feet of this type have guide grooves of constant width for guiding the edges of the material being sewn. Therefore, in order to completely satisfactorily feed materials of different thicknesses it is necessary to use the particular foot from a plurality of presser feet whose guide groove is matched to a thickness of material to be sewn which within the range of specific material thickness fluctuations prevents a flapping or tilting of the edges of material in front of the trimming station.

To avoid stocking various presser feet with guide grooves of different width, an aim of the invention is to adapt the guide groove of the presser foot fixed to the machine to the material being sewn. To this end there is provided according to the invention a presser foot comprising a horizontal trimming device having a trimming station for trimming the upturned edges of a material which pass through the station, and a base of the presser foot which cooperates with the trimming device, having a guide groove, for guiding the material through the foot, extending from a position in front of the trimming station of the trimming device to a position behind said trimming station, the groove being laterally defined by two deflectors being laterally adjustable.The adaption of the guide groove of the presser foot is achieved in that part of the guide groove located in front of the trimming device and is bounded by -two adjustable deflectors. This alleviates the timeconsuming changing of the presser feet on changing the thickness of the material to be sewn which, due to the incorporated trimming device, had to be performed by an expert. In the case of a presser foot with two parallel, forwardly projecting toes, the deflectors are advantageously connected to mounting supports fixed to the toes.

One embodiment according to the invention will now be described, by way of example only, with reference to the accompanying illustrative drawings in which: Fig. 1 is a perspective view of the pressure foot, Fig. 2 is a section along the line II-II of Fig. 1, and Fig. 3 is a perspective view of one deflector and its mounting support.

The presser foot has a shaft 1 provided with a vertically directed bore 2 for receiving a presser bar 3 known per se. Shaft 1 is split by a slot 4 running lengthwise relative to bore 2 and can be fixed by means of a screw 5 to presser bar 3.

To shaft 1 is connected a base 6 having a needle hole 7 alongside which extend in the forwards direction two parallel toes 8, 9, forming the lateral boundary of a guide groove 10 which extends from the front end of the presser foot to behind the later described trimming portion. In order to compensate automatically changes in the thickness of the material to be sewn passing under the presser foot, guide shoes 11, 12 made from flexible sheet metal and of the same width as toes 8, 9 are provided. The shape of guide shoes 11, 12 is such that a slightly downwardly curved central portion is followed in each case by an upwardly curved end portion adapted to the curved end portion of toes 8, 9 or base 6 and ending in inwardly overlapping chamfered ends.The front ends are screwed to toes 8, 9 by means of screws 13, 14, whilst the rear ends engage laterally on the shaft 1 and are secured against lateral displacement by a bracket 15 which connects the same.

The inside of toe 9 (Fig. 2) is provided with a chamfer 16. A vertically directed deflector 17 which passes downwardly into an inclined plane 18 parallel to chamfer 16 projects into guide groove 10. A bent mounting support 1 connected to deflector 17 is located on the front end of guide shoe 12 and is fixed to toe 9 by screw 14. Deflector 17 is laterally adjustable by means of a slot 20 in the mounting support 19.

A deflector 21 extends laterally from the inside of the other toe 8 and by means of a mounting support 22, together with the front end of guide shoe 11 is fixed by screw 13 to toe 8. Here again, deflector 21 is laterally adjustable in mounting support 22 as a result of slot 23.

A deflecting plate 25 is fixed by means of a screw 24 to the right-hand toe 9 and extends laterally over the left-hand toe 8 in front of hole 7.

During the advance of the material to be sewn, below base 6 of the presser foot, the upturned edges of the material are cut to a uniform height by a pair of cooperating trimming blades 26, 27. Fixed trimming blade 26 is located in a dovetailed transverse slot 28 of toe 8 and is held in position by a clamping plate 29 which is braced to trimming blade 26 by means of a screw 30. The movable trimming blade 27 is adjustably fixed-to the end of an arm 31, which in a manner not shown is connected with cutting drive known a per se.

At its front end, cutting blade 27 has a projection 32 which drags on the surface of fixed trimming blade 26. Trimming blade 27 is swung at right angles over the feed line by the cutting drive not shown and by cooperating with fixed trimming blade 26 progressively trims the upturned edges of the material to be sewn which is advanced under the base 6 of the presser foot. The cut edges are laterally displaced out of the sewing area by deflecting plate 25.

Immediately below the trimming station, guide shoe 11 is provided with an inclined rearwardly directed widened portion 33, whose front edge is bent upwards. Widened portion 33 serves to turn the upwardly directed edge of the left-hand layer of material downwards following trimming, whilst the edge of the right-hand layer of material, aided by the inclined plane 18 following deflector 17 is positioned above it.

Thus, the material edges trimmed in the raised position are turned over flat after trimming and are sewn in overlapped manner with a flat seam.

Due to the lateral adjustability of the two deflectors 17, 21 their spacing can be adapted satisfactorily to the thickness of the traversing edges of the material to be sewn. In addition, its lateral position can be adjusted in such a way that the infeed of material can be pre cisely adapted to the cutting conditions, leading to better sewing results.

WHAT WE CLAIM IS: 1. A presser foot comprising a horizontal trimming device having a trimming station for trimming the upturned edges of a material which pass through the station, and a base of the presser foot which cooperates with the trimming device, having a guide groove, for guiding the material through the foot, extending from a position in front of the trimming station of the trimming device to a position behind said trimming station, the groove being laterally defined by two deflectors being laterally adjustable.

2. A presser foot as claimed in Claim 1, in which the two deflectors are adjustable laterally independently of each other and transversely to the sewing direction.

3. A presser foot as claimed in Claim or Claim 2, in which the deflectors are mounted on mounting supports which supports are mounted one on each of two parallel forwardly projecting toes.

4. A presser foot as claimed in Claim 3, in which the base and the two projecting toes a integral.

5. A presser foot as claimed in any one of the preceding claims, in which the trimming device comprises a fixed blade and a movable blade which cooperate to cut upturned edges of material at the trimming station.

6. A presser foot as claimed in Claim 5, in which the movable cutting blade includes a projection which drags on the surface of the fixed trimming blade, the movable trimming blade being moved over the feed line of the material through the trimming station by a drive means.

7. A presser foot as claimed in any one of the preceding claims, including a deflector plate located behind the trimming station for displacing cut portions of material from the trimming station.

8. A presser foot as claimed in any one of the preceding claims, in which a guide shoe is provided on one side of the groove and a portion of the deflector on the other side after the trimming station to assist in turning the edges of the trimmed material overflat after trimming.

9. A presser foot substantially as herein described with reference to the accompanying illustrative drawings.

10. A sewing machine including a presser foot as claimed in any one of the preceding

Claims (1)

1. claims.