Hem stitching presser foot for a zigzag sewing machine

A hand stitching presser foot, for a zigzag sewing machine having a fabric feed direction and a presser foot holder, for forming a hem on a fabric, the presser foot consisting of a fabric presser member pivotally mounted to the presser foot holder and having one end, an elastic fabric presser portion and a cutout having an open edge extending in the fabric feed direction, the cutout forming a needle drop hole on an edge of the cutout opposite from the open edge, a fabric guide member disposed a distance from the presser foot holder, fixed to the fabric presser member at one end and adjacent to the open edge, the fabric guide member forming a fabric guide portion having a vertical face disposed substantially along the fabric feed direction for guiding the fabric in the fabric feed direction, and a thread guide member having a thread guide portion fixed to the fabric guide member and arranged so as to extend across the cutout in the region of the open edge, the elastic fabric presser portion being located between the thread guide portion of the thread guide member and the needle drop hole of the fabric presser member, and being formed so as to press against the fabric being sewn.

BACKGROUND OF THE INVENTION 
The present invention relates to a hem stitching presser foot for a zigzag 
sewing machine which forms stitches using upper and lower thread, whereby 
stitches equivalent to hem stitches produced by over-lock or inter-lock 
sewing machines are satisfactorily produced. 
It is widely known that fabric hems of sewn products are easily frayed 
thereby spoiling the outer appearance of the sewn product and yielding a 
shorter length of service of the sewn product. To avoid such 
disadvantages, many types of hem stitches including manual types are 
produced. The over-lock or interlock sewing machines can produce a number 
of hem stitches very rapidly, however, these sewing machines are expensive 
and are professionally used for only a single function. Notwithstanding 
the necessities thereof, it is uneconomical and difficult to furnish such 
sewing machines for ordinary home use. When not using such professional 
sewing machines zigzag stitching is normally performed as hem stitching 
along the fabric hem by means of a single needle. But since such hem 
stitching does not include the threads to cover the hem along the fabric 
edge, it is inferior in comparison with the stitching produced by the 
above-mentioned professional sewing machine. Therefore, hem stitches of 
high grade have not been realized in ordinary home sewing. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to remove the defects of the prior 
art as mentioned above. 
An object of the present invention is to produce stitches equivalent to hem 
stitches produced by over-lock or inter-lock sewing machines by devising 
an easy process for using a fabric pressor on a zigzag sewing machine. 
Another object of the present invention is to produce stitches without 
defects by providing a fabric pressor which presses the fabric beneath the 
needle hole thereby preventing disorientation of the fabric during 
stitching.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will be explained in accordance with the embodiments 
shown in the drawings. A fabric presser member 1 has a bottom 1b and is 
pivoted to a presser foot holder 2 which is fixed to a lower end of a 
presser bar attached to a machine head (both not shown). The presser 1 is 
centrally formed with a cut out comprising a needle drop hole 1a, and is 
secured with a fabric guide member 3, of an elastic member, over the 
needle drop hole 1a opposite to the pressor foot holder 2. The fabric 
guide member 3 is formed with a fabric guide portion 3a which is disposed 
along the fabric feed direction shown by the arrow in FIG. 1 and has a 
bottom 3b that projects below the bottom 1b of the presser 1. A thread 
guide member 5, made of a heat-treated steel wire, is fixed at its base to 
the fabric guide member 3 of the presser 1. A thread guide portion 5b is 
disposed along the feed direction outside of the fabric guide portion 3a 
and toward the presser foot holder 2. The thread guide portion 5b has a 
bottom which is slightly above the bottom 1b of the presser 1. 
An elastic fabric presser member 6 is formed in a U-shape and has a basic 
portion that is held to the fabric guide member 3. The fabric presser 
member 6 is formed with two fabric pressers 6a extending parallel to one 
another in the fabric feed direction. The fabric pressers 6a elastically 
press the fabric between the thread guide portion 5b of the thread guide 
member 5 and the needle drop hole 1a of the presser 1. 
An embodiment of the present invention is constructed as mentioned above, 
and its operation will next be described. FIG. 4 shows one example of the 
pattern formed by the present device. The pattern is stored electronically 
in a microcomputer (not shown) or mechanically by pattern cams (not 
shown). In FIG. 4, stitches a1, a5 are formed on fabric 7. The stitch a8 
is formed at the hem 7a of the fabric 7, and the stitches a3, a4 are 
formed outside of the thread guide portion 5b. One cycle of hem stitching 
contains the stitches a1, a2, a3, a4, and a5. The stitches are formed as 
the fabric guide portion 3a of the guide member 3 lightly touches the hem 
7a of the fabric 7. As shown in FIG. 5, the stitches a1, a5 are formed on 
the fabric 7, the stitch a2 is formed at the hem 7a of fabric 7, and 
stitches a3, a4 are formed along the right side of the thread guide 
portion 5b of the thread guide member 5. A stitch a'2 of a subsequent 
cycle, is formed in a thread loop 8 which is formed by the stitches a1, 
a2, a3, a4, and a5 of the previous cycle. Thus, the hem stitching at the 
hem 7a of the fabric 7 is produced as shown in FIG. 6 where it is shown 
that TU is an upper thread and TL is a lower thread. As seen from FIG. 6, 
since the upper thread TU and the lower thread TL are disposed in such a 
way as to cover the hem 7a of fabric 7, the hem stitching which is 
equivalent to hem stitching by the over-lock sewing machine may be 
obtained. 
Since the fabric 7 is elastically pressed by the fabric presser 6a of the 
presser member 6, the fabric 7 is prevented from vertical displacement 
caused by friction with the needle, and undesirable stitches may be 
avoided. 
FIGS. 7 and 9 show another embodiment of patterns of hem stitches produced 
by the present invention. FIGS. 10 and 11 show stitches formed by these 
patterns. 
In FIG. 7, the stitches b1, b6 are formed on the fabric 7, the stitches b2, 
b4 formed at the hem 7a of the fabric 7, and the stitches b3, b5 are 
formed outside of the thread guide portion 5b. The stitches b'1, b'2 are 
part of the stitches of a subsequent cycle. 
FIG. 10 stitches formed by the pattern shown in FIG. 7, and a stitch b'2 
formed in the thread loop 8. 
In FIG. 8, stitches c1, c5 and c6 are formed on the fabric 7, a stitch c2 
is formed at the hem 7a of the fabric 7, and stitches c3 and c4 are formed 
outside of the thread guide portion 5b. Stitches c'1, c'2 are part of a 
subsequent stitching cycle. FIG. 11 shows the stitching produced by the 
pattern shown in FIG, 8, and a stitch c'2 formed in a thread loop 8. 
In FIG. 9, stitches d1, d6 and d7 are formed on the fabric 7, stitches d2 
and d4 are formed at the hem 7a of the fabric 7, and stitches d3 and d5 
are formed outside of the thread guide portion 5b. Stitches d'1 and d'2 
are part of a subsequent cycle. 
FIG. 12 shows the stitches produced by the pattern shown in FIG. 9, and 
since a sew-up 10 is formed on the fabric 7, the stitches are thereby 
equivalent to hem stitches produced by an inter-lock sewing machine. A 
stitch d'2 is also formed in the thread loop 8. 
The embodiment of the present invention is constructed and operated as 
mentioned above. Stitches equivalent to hem stitches by an over-lock 
sewing machine or an interlock sewing machine may be produced by an easy 
process using the presser foot on a zigzag sewing machine which forms 
straight stitches from upper and lower threads. The elastic fabric 
pressing member 6 which presses the fabric in the area of needle 
penetration is provided so that undesirable stitches may be avoided.