TECHNICAL FIELD
[0001] This disclosure relates to a presser foot for a sewing machine, which presses a stepped
portion of a work material for restricting an unexpected movement of the work material.
BACKGROUND DISCUSSION
[0002] As shown in Fig. 32, a known presser foot 60 for a sewing machine includes a bottom
face 61 having a flat surface, a front presser portion 64, and a rear presser portion
67. A needle receiving hole 62 is formed in the center of the bottom face 61. The
presser foot 60 is configured so that the bottom face 61 surely presses a work material
(fabric) to thereby prevent the work material from moving vertically in conjunction
with a vertical movement of a sewing needle (such vertical movement of the work material
resembles a waving flag and therefore will be referred to as "flagging"). For example,
as shown in Fig. 33, in the case of hemming jeans or sewing belt loops, when a stepped
portion 10 of the fabric, which includes three, nine, and three folds, is sewn by
the sewing machine, the front presser portion 64 is moved up on the stepped portion
10 via a rear end portion 63 of the bottom face 61 serving as a supporting point.
Further, since a rotary pin 4 is arranged adjacent to the rear end portion 63, the
rotary pin 4 is moved upward simultaneously when the front presser portion 64 is moved
up on the stepped portion 10.
[0003] Thus, as illustrated in Fig. 34 and Fig. 35, a thickest portion of the stepped portion
10 is fed close to the rotary pin 4 and afterwards passes the rotary pin 4, i.e. the
presser foot 60 is moved up on and down from the stepped portion 10. When the thickest
portion of the stepped portion 10 is fed close to the rotary pin 4, the work material
may be forcibly moved backward in the opposite direction of a feed direction of the
work material because of a presser bar pressure and may not be appropriately fed because
of a sudden upward movement of the rotary pin 4.
[0004] Further, as shown in Fig. 33, when the front presser portion 64 is in contact with
the stepped portion 10, a space 68 having an approximately triangular shape is formed
by an upper corner of the stepped portion 10, a lower end 66 of the stepped portion
10, and the rear presser portion 67. Under such condition, the work material in a
space 68 is not surely pressed by the presser foot 60. Accordingly, when a sewing
needle 6 penetrates through into the work material, thread loops may not be formed
uniformly because the work material is not surely pressed by the presser foot 60.
As a result, sewing defects such as skipped stitches occur. Such sewing defects may
occur in a similar way as in the case where the presser foot 60 is moved down from
the stepped portion 10 (see Fig. 35).
[0005] A known presser foot disclosed in
JP1991-65570U (hereinafter referred to as Reference 1) includes a presser plate rotatably attached
to a lower end of a presser holder via a pivot shaft. Recessed portions are formed
at lateral sides of a bottom face of the presser plate so as to be positioned approximately
directly below the pivot shaft.
[0006] Further, a presser foot for a sewing machine, disclosed in
JP1996-141251A (hereinafter referred to as Reference 2) includes front and rear presser feet arranged
in a feed direction of a work material. The front and rear presser feet are rotatably
attached to a presser arm. A first coil spring is arranged between the front and rear
presser feet and a second coil spring is arranged between the rear presser foot and
the presser arm. When the front presser foot rotates in a direction departing from
a bed surface, a biasing force is applied to the rear presser foot by the first coil
spring so that the front presser foot is moved close to the bed surface.
[0007] Furthermore, a known fabric feed control apparatus for a sewing machine is disclosed
in
JP 1993-161771A (hereinafter referred to as Reference 3). The fabric feed control apparatus includes
a sensor detecting a stepped portion of a work material (fabric) when a front end
or the stepped portion of the work material approaches a contact portion with a presser
foot. When detecting the stepped portion, the sensor transmits a detection signal
to a CPU. Afterwards, the CPU issues a command to reduce a pressure of the presser
foot; thereby, a horizontal moving distance of feed dogs is increased.
[0008] The presser foot described in Reference 1 is more easily moved up on and down from
a stepped portion of a work material by means of the recessed portions of the bottom
face of the presser foot. However, when the length of the recessed portions is short
in a feed direction of a work material, the presser foot is difficultly moved up on
a stepped portion of the work material because of a flat portion of the bottom face
of the presser foot. When the length of the recessed portion is long in the feed direction,
a portion around a needle receiving hole is recessed. Accordingly, the presser foot
may not prevent a fluttering movement of the work material. In addition, the presserfoot
may not surely press the work material flatly and may not prevent the fluttering movement
of the work material while the presser foot is moved up on and down from the stepped
portion of the work material.
[0009] Moreover, according to the presser foot including the front and rear divided presser
feet as described in Reference 2, when the work material is backstitched (reversely
fed) in a condition where the front presser foot is moved down from the stepped portion,
a rear end of the front presser foot is not moved up on the stepped portion again,
therefore causing thread tangling. Further, when the presser foot is attached to the
sewing machine, the front presser foot tilts downward, therefore causing a user to
have difficulties feeding the work material under the presser foot. Furthermore, the
presser foot has a complicated configuration and includes more components, therefore
increasing manufacturing costs of the presser foot.
[0010] In addition, according to the fabric feed control apparatus described in Reference
3, the sensor detects an inclination of the presser foot and transmits the detection
signal to the CPU. Accordingly, the CPU processes the detection signal and outputs
the processed detection signal to an actuator controlling the pressure of the presser
foot and to an actuator controlling a fabric feed amount. As s result, a feeding condition
is adjusted in order to easily feed the stepped portion of the work material. The
fabric control apparatus includes such sensor and actuators and therefore is applied
only to a very expensive sewing machine. Accordingly, the fabric control apparatus
may not be applicable to various models of sewing machines.
[0011] A need thus exists for an inexpensive presser foot for a sewing machine, which prevents
skipped stitches at a stepped portion of a work material, appropriately feeds the
work material, and applies to various models of sewing machines.
SUMMARY
[0012] According to the invention there is provided a presser foot for a sewing machine
according to claim 1 herein. The invention accordingly provides a presser foot for
a sewing machine, comprising a main body capable of being pivotally attached to a
presser holder of the sewing machine via a pivot shaft so as to press a work material
being sewn by the sewing machine against a work bed of the sewing machine, the main
body of the presser foot having:
a needle receiving hole and
a restriction member or work material control means pivotally attached to the main
body and including a portion capable of protruding downwardly from a bottom face of
the main body to press against a work material being sewn by the sewing machine even
when the presser foot rides up and over a height discontinuity of a stepped portion
of the work material being sewn.
[0013] For example, when the stepped portion is moved to a contact position with a front
portion of the presser foot, the space having an approximately triangular shape is
formed between the stepped portion and the presser foot (in an area where a sewing
needle is moved downward). At this time, the restriction portion presses the work
material to restrict the movement of the work material. Accordingly, thread loops
are uniformly formed and skipped stitches are prevented. Such action of the restriction
portion is effective when the presser foot is moved up on and down from the stepped
portion. Further, the presser foot is formed by two types of components such as the
main body (for example, formed by die-cast portion of zinc alloy) and the restriction
member including the restriction portion; therefore, materials and a manufacturing
process of the presser foot are easily provided. Furthermore, when the presser foot
is applied to the sewing machine, a body of the sewing machine does not require a
special configuration. Accordingly, the presser foot may be applicable to conventional
sewing machines and optionally provided thereto.
[0014] According to another aspect of the disclosure, the restriction member and the restriction
member are formed with resin so as to form a single-piece member.
[0015] Accordingly, the restriction member is manufactured at low cost and easily attached
to the presser foot.
[0016] According to further aspect of the disclosure, the restriction portion is an elastic
member pressing the work material by means of an elastic force.
[0017] Accordingly, the restriction portion is the elastic member pressing the work material
by means of the elastic force and therefore elastically biases the restriction member.
Thus, the restriction member does not need a biasing member (for example, a compression
coil spring) for protruding the restriction portion from the bottom face of the main
body of the presser foot. As a result, the number of components for the presser foot
is minimized.
[0018] According to still further aspect of the disclosure, at least two or more restriction
portions are arranged at the restriction member so that the needle receiving hole
is positioned between the restriction portions.
[0019] Accordingly, the movement of the work material around the needle receiving hole is
restricted by two imaginary lines defined by the restriction portions (in the case
of three or more restriction portions, an imaginary surface defined by the restriction
portions); therefore, thread loops are uniformly formed and skipped stitches are inhibited.
[0020] According to another aspect of the disclosure, the restriction member includes a
supplementary restriction member positioned in the needle receiving hole and holding
the work material along a feed direction thereof.
[0021] Accordingly, the movement of the work material around the needle receiving hole 133
is prevented, therefore forming thread loops more effectively.
[0022] According to further aspect of the disclosure, wherein the bottom face of the main
body has inclined portions and a deepest portion between the inclined portions is
positioned further rearward than the pivot shaft in the feed direction.
[0023] Accordingly, for example, in the case where the stepped portion of a thick work material
is sewn (in the case of hemming jeans), the inclination of the presser foot when the
presser foot is moved up on the stepped portion is decreased, therefore reducing an
upward movement of the pivot shaft transmitting a presser bar pressure to the work
material. Further, even when the stepped portion is inserted directly under the pivot
shaft, the pivot shaft does not necessarily move upward so as to be higher than the
thickness of the stepped portion of the work material and the work material is smoothly
fed under the presser foot. Furthermore, the inclination of the presser foot allows
the stepped portion to be pressed along shapes of the inclined portions. Accordingly,
a rear portion of the bottom face, which is located rearward than the pivot shaft
is easily moved up on the stepped portion. The upward movement of the pivot shaft
gently varies; thereby, the presser foot is easily moved up on and down from the stepped
portion. The inclined portions are formed so as to extend to the needle receiving
hole. Accordingly, in the case of sewing a thin work material, a portion of the thin
work material, which is positioned around the needle receiving hole may not be pressed
by the main body of the presser foot. However, the main body is combined with the
restriction member; thereby the portion of the thin work material around the needle
receiving hole is pressed by the restriction member to inhibit skipped stitches accordingly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The foregoing and additional features and characteristics of this disclosure will
become more apparent from the following detailed description considered with the reference
to the accompanying drawings, wherein:
[0025] Fig. 1 is a perspective view of a presser foot for a sewing machine according to
a first embodiment disclosed here;
[0026] Fig. 2A is a top view of a main body of the presser foot according to the first embodiment
disclosed here;
[0027] Fig. 2B is a lateral view of the main body of the presser foot according to the first
embodiment disclosed here;
[0028] Fig. 2C is a bottom view of the main body of the presser foot according to the first
embodiment disclosed here;
[0029] Fig. 2D is a cross-sectional view of the main body of the presser foot according
to the first embodiment, taken along the line 2D-2D of Fig. 2A;
[0030] Fig. 3A is a top view of a restriction member including plate springs according to
the first embodiment disclosed here;
[0031] Fig. 3B is a lateral view of the restriction member according to the first embodiment
disclosed here;
[0032] Fig. 3C is a bottom view of the restricting member according to the first embodiment
disclosed here;
[0033] Fig. 3D is a cross-sectional view of the restriction member according to the first
embodiment, taken along the line 3D-3D of Fig. 3A;
[0034] Fig. 4A is a top view of an assembled condition of the presser foot according to
the first embodiment where the restricting member is attached to the main body;
[0035] Fig. 4B is a lateral view of the assembled condition of the presser foot according
to the first embodiment;
[0036] Fig. Fig. 4C is a bottom view of the presser foot according to the first embodiment;
[0037] Fig. 4D is a cross-sectional view showing the assembled condition of the presser
foot according to the first embodiment, taken along the line 4D-4D of Fig. 4A;
[0038] Fig. 5 is an explanation drawing showing a condition before a stepped portion of
a work material is moved to a contact position with the presser foot according to
the first embodiment;
[0039] Fig. 6 is an explanation drawing showing a condition where the presser foot according
to the first embodiment starts being moved up on the stepped portion of the work material;
[0040] Fig. 7 is an explanation drawing showing a condition where the stepped portion of
the work material is moved to a contact position with a front inclined portion of
the presser foot according to the first embodiment;
[0041] Fig. 8 is an explanation drawing showing a condition where the stepped portion of
the work material is further fed close to a rotary pin;
[0042] Fig. 9 is an explanation drawing showing a condition where the stepped portion of
the work material is moved directly below the rotary pin;
[0043] Fig. 10 is an explanation drawing showing a condition where the stepped portion of
the work material passes directly below the rotary pin;
[0044] Fig. 11 is an explanation drawing showing a condition where a terminal portion of
the stepped portion of the work material is moved under the rotary pin;
[0045] Fig. 12 is an explanation drawing showing a condition where a rear inclined portion
of the main body of the presser foot according to the first embodiment is moved down
from the stepped portion of the work material;
[0046] Fig. 13 is an explanation drawing showing a condition where the rear inclined portion
of the main body of the presser foot is in contact with the stepped portion of the
work material;
[0047] Fig. 14 is an explanation drawing showing a condition after the presser foot according
to the first embodiment is moved down from the stepped portion of the work material;
[0048] Fig. 15 is a perspective view of the presser foot according to a second embodiment
disclosed here;
[0049] Fig. 16A is a top view of the main body of the presser foot according to the second
embodiment disclosed here;
[0050] Fig. 16B is a lateral view of the main body of the presser foot according to the
second embodiment disclosed here;
[0051] Fig. 16C is a bottom view of the main body of the presser foot according to the second
embodiment disclosed here;
[0052] Fig. 16D is a cross-sectional view of the main body of the presser foot according
to the second embodiment, taken along the line 16D-16D of Fig. 16A;
[0053] Fig. 17A is a top view of the restriction member according to the second embodiment
disclosed here;
[0054] Fig. 17B is a lateral view of the restriction member according to the second embodiment;
[0055] Fig. 17C is a bottom view of the restriction member according to the second embodiment;
[0056] Fig. 17D is a cross-sectional view taken of the restriction member according to the
second embodiment, taken along the line 17D-17D of Fig. 17A;
[0057] Fig. 18A is a top view of an assembled condition of the presser foot according to
the second embodiment where the restriction member is attached to the main body;
[0058] Fig. 18B is a lateral view of the assembled condition of the presser foot according
to the second embodiment;
[0059] Fig. Fig. 18C is a bottom view of the assembled condition of the presser foot according
to the second embodiment;
[0060] Fig. 18D is a cross-sectional view of the presser foot according to the second embodiment,
taken along the line 18D-18D of Fig. 18A;
[0061] Fig. 19 is an explanation drawing showing a condition before the stepped portion
of the work material is moved to a contact position with the presser foot according
to the second embodiment;
[0062] Fig. 20 is an explanation drawing showing a condition where the presser foot according
to the second embodiment starts being moved up on the stepped portion of the work
material;
[0063] Fig. 21 is an explanation drawing showing a condition where the stepped portion of
the work material is moved to a contact position with the front inclined portion of
the presser foot according to the second embodiment;
[0064] Fig. 22 is an explanation drawing showing a condition where the stepped portion of
the work material is further fed close to the rotary pin;
[0065] Fig. 23 is an explanation drawing showing a condition where the stepped portion of
the work material is moved directly below the rotary pin;
[0066] Fig. 24 is an explanation drawing showing a condition where the stepped portion of
the work material passes directly below the rotary pin;
[0067] Fig. 25 is an explanation drawing showing a condition where the rear inclined portion
of the main body of the presser foot according to the second embodiment is moved down
from the stepped portion of the work material;
[0068] Fig. 26 is an explanation drawing showing a condition where the rear inclined portion
of the main body of the presser foot according to the second embodiment is in contact
with the stepped portion of the work material;
[0069] Fig. 27 is an explanation drawing showing a condition after the presser foot according
to the second embodiment is moved down from the stepped portion of the work material;
[0070] Fig. 28 is an explanation drawing of a third embodiment that is an modified example
of the second embodiment where a supplementary restriction member is attached to the
restriction member;
[0071] Fig. 29 is an explanation drawing showing a condition before the stepped portion
of the work material is moved to a contact position with the presser foot according
to the third embodiment;
[0072] Fig. 30 is an explanation drawing illustrating a condition where the stepped portion
of the work material is moved to a contact position with the front inclined portion
of the presser foot according to the third embodiment;
[0073] Fig. 31 is an explanation drawing illustrating a condition where the rear inclined
portion of the main body of the presser foot according to the third embodiment is
in contact with the stepped portion of the work material;
[0074] Fig. 32 is an perspective view of a known presser foot;
[0075] Fig. 33 is an explanation drawing showing a condition while the known presser foot
is moved up on the stepped portion of the work material;
[0076] Fig. 34 is an explanation drawing showing a condition while the known presser foot
is moved up on the stepped portion of the work material; and
[0077] Fig. 35 is an explanation drawing showing a condition while the known presser foot
is moved down from the stepped portion of the work material.
DETAILED DESCRIPTION
[0078] A first embodiment of a presser foot 1 for a sewing machine disclosed here will be
explained with reference to the attached drawings. In the following description, an
up-and down direction is a vertical direction that coincides with a moving direction
of a sewing needle 6. A front-and-rear direction corresponds to a feed direction of
a work material in the sewing machine. Left and right sides in the attached drawings
correspond to the front direction and the rear direction, respectively.
[0079] Fig. 1 is a perspective view of the presser foot 1 according to the first embodiment.
The presser foot 1 includes a main body 20, a restriction member 40 for restricting
a vertical movement of the work material, and two plate springs serving as restriction
portions (elastic members) 50 attached to the restriction member 40. The vertical
movement of the work material resembles a waving flag and therefore will be referred
to as "flagging" hereinafter. Thus, the restriction member 40 is to be read as a flagging-preventing
member 40.
[0080] Fig. 2A is a top view of the main body 20 of the presser foot 1. Fig. 2B is a lateral
view of the main body 20. Fig. 2C is a bottom view of the main body 20. Fig. 2D is
a cross-sectional view of the main body 20 taken along the line 2D-2D of Fig. 2A.
A presser holder 2 transmitting a presser bar pressure of a presser bar spring to
the main body 20 is arranged at the main body 2 (see Fig. 5). The presser holder 2
is fixed to a presser bar 3 that is vertically movable (see Fig. 5). The main body
20 of the presser foot 1 is movably attached to the presser holder 2 via a pivot pin
(pivot shaft) 4.
[0081] As shown in Figs. 2A to 2D, a bottom face 21 of the main body 20 of the presser foot
1 includes flat faces 22, a front inclined portion (inclined portion) 23, and a rear
inclined portion (inclined portion) 24. A deepest portion 25 between the front inclined
portion 23 and the rear inclined portion 24 is positioned further rearward than the
rotary pin 4. A needle receiving hole 33 is formed in the approximately center of
the main body 20. The sewing needle 6 penetrates through the needle receiving hole
33. A first accommodating portion 27 and a second accommodating portion 28 are arranged
in the bottom face 21. The first accommodating portion 27 accommodates a pass over
portion 42 (see Fig. 3) of the restriction member 40 in accordance with a rotation
of the restriction member 40 while the second accommodating portion 28 accommodates
a pressing portion 41 (shown in Fig. 3) pressing the work material around the needle
receiving hole 33, in accordance with the rotation of the restriction member 40. Thus,
the bottom face 21 of the main body 20 of the presser foot 1 is flatly connected to
either one of the pass over portion 42 and the pressing portion 41. Further, first
and second recessed potions 31 and 32 are formed in the bottom face 21 for preventing
the main body 20 from contacting a contact portion 5 of the presser holder 2. Holes
26 are formed in lateral faces of the main body 20. Shafts 43 of the restriction member
40 are inserted into the holes 26 of the main body 20. Furthermore, the rotary pin
4 is attached to the main body 20.
[0082] Fig. 3A is a top view of the restriction member 40 including the plate springs 50.
Fig. 3B is a lateral view of the restriction member 40. Fig. 3C is a bottom view of
the restriction member 40. Fig. 3D is a cross-sectional view of the restriction member
40 taken along the line 3D-3D of Fig. 3A. The restriction member 40 includes the pressing
portion 41 and the pass over portion 42. The plate springs 50 are attached to lateral
faces of the restriction member 40. The shafts 43 are arranged at inner portions of
the lateral faces of the restriction member 40. The restriction member 40 and the
plate springs 50 are formed with resin so as to form a single-piece member.
[0083] Fig. 4A is a top view of an assembly condition of the presser foot 1 in which the
restriction member 40 is attached to the main body 20. Fig. 4B is a lateral view of
the assembled condition of the presser foot 1. Fig. 4C is a bottom view of the assembled
condition of the presser foot 1. Fig. 4D is a cross-sectional view of the assembled
condition of the presser foot 1 taken along the line 4D-4D of Fig. 4A. The shafts
43 are fitted in the holes 26 to thereby movably attach the restriction member 40
to the main body 20.
[0084] Details of an operation of the presser foot 1 according to the first embodiment will
be described with reference to Figs. 5 to 14 as follows.
[0085] Fig. 5 shows a condition before a stepped portion 10 of the work material is fed
close to the presser foot 1. In Fig. 5, the presser foot 1 presses (three folds of
the stepped portion of) the work material. An elastic force of the plate springs 50
of the restriction member 40 is set to be surely smaller than the presser bar pressure.
Accordingly, the plate springs 50 are elastically deformed and moved upward as seen
in Fig. 5. Further, the pass over portion 42 is accommodated in the accommodating
portion 27 of the main body 20 by the presser bar pressure. Furthermore, since the
pass over portion 42 is pressed against the work material by the presser bar pressure,
a portion of the work material, which is around the needle receiving hole 33, is pressed
by the pressing portion 41 via the shafts 43. Such condition is seen similarly in
the case of sewing a thin work material, therefore preventing skipped stitches.
[0086] Fig. 6 shows a condition where the presser foot 1 starts being moved up on the stepped
portion 10. A space 11 having an approximate triangular shape is formed between the
presser foot 1 and the work material. At this time, flagging of the work material
is restricted by the elastic force (restoring force) of the plate springs 50 arranged
at the restriction member 40 to thereby prevent a non-uniform formation of thread
loops. Further, skipped stitches are prevented while the presser foot 1 is moved up
on the stepped portion 10.
[0087] Fig. 7 shows a condition where the stepped portion 10 is moved to a contact position
with the front inclined portion 23 of the presser foot 1. In this condition, an upper
corner of the stepped portion 10 is in contact with the front inclined portion 23
of the main body 20 and the presser bar pressure is not applied to the pass over portion
42 of the restriction member 40. Further, the pressing portion 41 is accommodated
in the second accommodating portion 28 of the main body 20 by the elastic force (restoring
force) of the plate springs 50.
[0088] Fig. 8 shows a condition where the stepped portion 10 of the work material is further
fed close to the rotary pin 4. In this condition, the presser bar pressure is stronger
than the elastic force of the plate springs 50 and therefore elastically deforms the
plate springs 50. At this time, an inclination α of the presser foot 1 is reduced
by approximately 40 percent as compared with an inclination β of a known presser foot
60 (see Fig. 34). Further, a height h1 of the rotary pin 4 from the work material
is shorter by approximately 10 percent as compared with a height h2 of the rotary
pin 4 of the known presser foot 60 (see Fig. 34). Accordingly, a resistive force (acting
in the opposite direction from the feed direction) of the rotary pin 4, occurring
relative to the work material until the stepped portion 10 is moved directly below
the rotary pin 4 is reduced and variations of a load of the presser bar pressure is
reduced; therefore, the work material is smoothly fed to pass under the presser foot
1.
[0089] Fig. 9 shows a condition where the stepped portion 10 of the work material is moved
directly below the rotary pin 4. In this condition, the presser bar pressure is applied
to a whole area of the front inclined portion 23 of the main body 20 of the presser
foot 1. Since the deepest portion 25 that is an inflexion point between the front
inclined portion 23 and the rear inclined portion 24 of the main body 20 is located
further rearward than the rotary pin 4, the condition shown in Fig. 9 is realized
due to the principle of leverage.
[0090] Fig. 10 shows a condition where the stepped portion 10 of the work material passes
directly below the rotary pin 4. In this condition, the upper corner of the stepped
portion 10 is in contact with the rear inclined portion 24 of the main body 20. At
this time, the height of the rotary pin 4 varies but an amount of the variation is
small; therefore, feeding of the work material is not inhibited.
[0091] Fig. 11 shows a terminal portion of the stepped portion 10 of the work material is
moved approximately below the rotary pin 4. In this condition, the space 11 having
the approximately triangular shape is formed between the stepped portion 10 and the
presser foot 1 in the same manner as seen while the presser foot 1 is moved up on
the stepped portion 10. In addition, flagging of the work material is restricted by
the plate springs 50 of the restriction member 40; therefore, skipped stitches are
inhibited.
[0092] Fig. 12 shows a condition before a rear end inclined portion 29 of the main body
20 of the presser foot 1 is moved down from the stepped portion 10 of the work material.
In this condition, the presser foot 1 is moved down from the stepped portion 10 while
flagging of the work material in the space 11 formed between the main body 20 and
the stepped portion 10 is restricted by the plate springs 50 of the restriction member
40. At this time, the pressing portion 41 is not in contact with the stepped portion
10 and a load is not applied to the pressing portion 41. Further, the pass over portion
42 is accommodated in the first accommodating portion 27 of the main body 20 by the
presser bar pressure. When the work material is backstitched (reversely fed) under
the condition shown in Fig. 12, the presser foot 1 is easily moved up on and down
from the stepped portion 10.
[0093] Fig. 13 shows a condition where the rear end inclined portion 29 of the main body
20 of the presser foot 1 is in contact with the stepped portion 10 of the work material.
As seen in Fig. 35, a downwardly inclined angle of the known presser foot 60 is not
sufficient for the presser foot 60 to press the work material. When feed dogs move
lower than a needle plate surface, the stepped portion 10 is moved forcibly or suddenly
in the feed direction by a rear end inclined portion 69 of the known presser foot
60 because of the presser bar pressure. Accordingly, a feed amount of the work material
is increased. As a result, the sewing needle 6 may be bent by the forcible or sudden
movement of the work material. Meanwhile, according to the presser foot 1 described
in the first embodiment, a forwardly inclined angle of the main body 20 is increased
by the receded portions 31 and 32 preventing the main body 20 from interfering with
the contact portion 5 of the presser holder 2 arranged at the main body 20. Further,
the work material is held by the presser bar pressure applied to the main body 20,
via the pass over portion 42 of the restriction member 40. As a result, the work material
is inhibited from being forcibly or suddenly moved in the feed direction.
[0094] Fig. 14 shows a condition after the presser foot 1 is moved down from the stepped
portion 10 of the work material. In Fig. 14, the plate springs 50 of the restriction
member 40 are elastically deformed and moved upward in the same manner as seen in
Fig. 5. In this condition, the pass over portion 42 is accommodated in the first accommodating
portion 27 by the presser bar pressure.
[0095] According to the press foot 1 of the first embodiment, the restriction member 40
is provided with the plate springs 50 protruding from the bottom face 21 of the main
body 20. Accordingly, when the stepped portion 10 is moved to a contact position with
a front portion of the presser foot 1, the space 11 having the approximately triangular
shape is formed between the stepped portion 10 and the presser foot 1. At this time,
the spring plates 50 press the work material to restrict the movement of the work
material. Accordingly, thread loops are uniformly formed and skipped stitches are
prevented. Such action of the spring plates 50 is effective when the presser foot
1 is moved up on and down from the stepped portion 10. Further, the presser foot 1
is formed by two types of components such as the main body 20 and the restriction
member 40 including the plate springs 50; therefore, materials and a manufacturing
process of the presser foot 1 are easily provided. Furthermore, when the presser foot
1 is applied to the sewing machine, a body of the sewing machine does not require
a special configuration. Accordingly, the presser foot 1 may be applicable to conventional
sewing machines and optionally provided thereto.
[0096] In addition, the restriction member 40 and the plate springs 50 are formed with the
resin so as to form the single-piece member. Accordingly, the restriction member 40
is manufactured at low cost and easily attached to the presser foot 1.
[0097] Moreover, the spring member 50 is the elastic member pressing the work material by
means of the elastic force and therefore elastically biases the restriction member
40. Thus, the restriction member 40 does not need a biasing member (for example, a
compression coil spring) for protruding the spring plates 50 from the bottom face
21 of the main body 20 of the presser foot 1. As a result, the number of components
for the presser foot 1 is minimized.
[0098] The plate springs 50 are arranged at the lateral faces of the restriction member
40 in a condition where the needle receiving hole 33 is positioned between the plate
springs 50. Accordingly, the movement of the work material around the needle receiving
hole 33 is restricted by two imaginary lines defined by the spring plates 50; therefore,
thread loops are uniformly formed.
[0099] In addition, the bottom face 21 of the main body 20 of the presser foot 1 is configured
so that the deepest portion 25 between the front inclined portion 23 and the rear
inclined portion 24 is positioned further rearward than the rotary pin 4. Accordingly,
for example, in the case where a stepped portion of a thick work material is sewn
(in the case of hemming jeans), the inclination of the presser foot 1 when the presser
foot 1 is moved up on the stepped portion is decreased, therefore reducing an upward
movement of the rotary pin 4 transmitting the presser bar pressure to the work material.
Further, even when the stepped portion 10 is inserted directly under the rotary pin
4, the rotary pin 4 does not necessarily move upward due to the position of the deepest
portion 25 so as to be higher than the thickness of the stepped portion 10 of the
work material; therefore, the work material is smoothly fed under the presser foot
1. Furthermore, after the stepped portion 10 passes the rotary pin 4 in the feed direction,
the inclination of the presser foot 1 allows the stepped portion 10 to be pressed
along shapes of the front inclined portion 23 and the rear inclined portion 24. Accordingly,
a rear portion of the bottom face 21, which is located further rearward than the rotary
pin 4 is easily moved up on the stepped portion 10. The upward movement of the rotary
pin 4 gently varies to thereby allow the presser foot 1 to easily move up on and down
from the stepped portion 10. In addition, the front inclined portion 23 and the rear
inclined portion 24 are formed so as to extend to the needle receiving hole 33. Accordingly,
when a thin work material is sewn by the sewing machine, a portion of the thin work
material, which is around the needle receiving hole 33 may not be pressed by the main
body 20 of the presser foot 1. However, the main body 20 is combined with the restriction
member 40; thereby the portion of the thin work material around the needle receiving
hole 33 is pressed by the restriction member 40. As a result, skipped stitches are
inhibited.
[0100] A second embodiment of a presser foot 101 for a sewing machine will be described
as follows. Fig. 15A is a perspective view of the presser foot 101 seen from above.
Fig. 15B is a perspective view of the presser foot 101 seen from below. The presser
foot 101 mainly includes a main body 120, a restriction member 140 restricting flagging
of a work material, compression coil springs 151 (see Fig. 18), and torsion coil springs
152 (see Fig. 18).
[0101] Fig. 16A is a top view of the main body 120 of the presser foot 101 according to
the second embodiment. Fig. 16B is a lateral view of the main body 120. Fig. 16C is
a bottom view of the main body 120. Fig. 16D is a cross-sectional view of the main
body 120 taken along the line 16D-16D of Fig. 16A. A presser holder 102 transmitting
the presser bar pressure of the presser bar spring to the main body 120 is arranged
at the main body 120 (see in Fig. 19). The presser holder 102 is fixed to a presser
bar 103 that is vertically movable (see Fig. 19). The main body 120 is movably attached
to the presser holder 102 via a pivot pin (pivot shaft) 104.
[0102] A bottom face 121 of the main body 120 of the presser foot 101 includes a front flat
face 122a, a rear flat face 122b, a front inclined portion (inclined portion) 123,
and a rear inclined portion (inclined portion) 124. A virtual deepest portion 125a
between the front inclined portion 123 and the rear inclined portion 124 is positioned
further rearward than the rotary pin 104. A needle receiving hole 133 is formed in
the approximately center of the main body 120. A sewing needle 106 (see Fig. 19) penetrates
through the needle receiving hole 133. An accommodating portion 128 is arranged in
the bottom face 121. The accommodating portion 128 accommodates a restriction portion
141 (see Fig. 17) of the restriction member 140 (see Fig. 17). The restriction portion
141 is accommodated in the accommodating portion 128 in accordance with a rotation
of the restriction member 140 so as to be flatly connected to the bottom face 121
of the main body 120 of the presser foot 101. Further, first and second recessed potions
131 and 132 preventing the main body 120 from contacting a contact portion 105 of
the presser holder 102 are formed in the bottom face 121. Holes 126 are formed in
lateral faces of the main body 120. Shafts 143 (see Fig. 17) of the restriction member
140 are inserted into the holes 126. Furthermore, recessed portions 156 therein retaining
the compression coil springs 151 (see Fig. 18) and fitting grooves 157 therein retaining
the torsion coil springs 152 (see Fig. 18) are arranged in the main body 20 of the
presser foot 101.
[0103] Fig. 17A is a top view of the restriction member 140 including the restriction portion
141. Fig. 17B is a lateral view of the restriction member 140. Fig. 17C is a bottom
view of the restriction member 140. Fig. 17D is a cross-sectional view of the restriction
member 140 taken along the line 17D-17D of Fig. Fig. 17. The restriction member 140
includes the restriction portion 141, rotation restriction pins 142, and coil spring
retaining portions 150. The shafts 143 are arranged at inner portions of lateral faces
of the restriction member 140. A cross-section of the restriction member 140 is formed
so as to conform to shapes of the front inclined portion 123 and the rear inclined
portion 124 in a condition where the restriction member 140 is accommodated within
the accommodating portion 128 of the main body 120. Under such condition, the virtual
deepest portion 125a is set at the restriction member 141.
[0104] Fig. 18A is a top view of an assembly condition of the presser foot 101 in which
the restriction member 140 is attached to the main body 120. Fig. 18B is a lateral
view of the assembled condition of the presser foot 101. Fig. 18C is a bottom view
of the assembled condition of the presser foot 101. Fig. 18D is a cross-sectional
view of the assembled condition of the presser foot 101 taken along the line 18D-18D
of Fig. 18A. The shafts 143 are fitted in the holes 126 to thereby movably attach
the restriction member 140 to the main body 120 of the presser foot 101. Further,
an allowable rotation range of the restriction member 140 is determined by the rotation
restriction pins 142 and a restriction surface 127 of the main body 120. Furthermore,
a load acting in a clockwise direction around the shaft 143 seen in Figs. 18B and
18D is consistently applied to the restriction member 140 by the compression coil
springs 151. The clockwise direction corresponds to a direction in which the restriction
portion 141 of the restriction member 140 protrudes downward from the bottom face
121 of the main body 120 of the presser foot 101. Thus, flagging of the work material
is prevented by the aforementioned action of the compression coil springs 151. In
addition, a load to tilt the whole presser foot 101 rearwardly downward relative to
a spring retaining surface 105a (see Fig. 19) around the rotary pin 104 is applied
to the presser foot 101 by the torsion coil springs 152. Thus, a feeding failure (i.e.
the work material is not fed appropriately) occurring when the presser foot 101 is
not tilted rearwardly downward, is prevented in the case where the presser foot 101
is moved up on a stepped portion 110 of the work material. As a result, the presser
foot 101 is easily moved up on the stepped portion 110.
[0105] Details of an operation of the presser foot 101 according to the second embodiment
will be described as follows with reference to Figs. 19 to 28.
[0106] Fig. 19 shows a condition before the stepped portion 110 of the work material is
moved to a contact position with the presser foot 101. In Fig. 19, the presser foot
101 presses (three folds of the stepped portion 110) of the work material. An elastic
force (restoring force) of the compression coil springs 151 applying the load to the
restriction member 140 is set to be surely smaller than the presser bar pressure.
Accordingly, the compression coil springs 151 is not resistive to the presser bar
pressure to thereby rotate the restriction member 140 around the shafts 143 in a counterclockwise
direction and a portion of the work material, which is positioned around the needle
receiving hole 133, is pressed by the front flat portion 122a, the rear flat portion
122b, and the restriction portion 141 of the restriction member 140. Such condition
is seen similarly in the case of sewing a thin work material. Thus, the portion of
the thin work material around the needle receiving hole 133 is pressed by the front
flat portion 122a, the rear flat portion 122b, and the restriction portion 141 of
the restriction member 140, therefore preventing skipped stitches.
[0107] Fig. 20 shows a condition where the presser foot 101 starts being moved up on the
stepped portion 110. A space 111 having an approximate triangular shape is formed
between the presser foot 101 and the work material. At this time, flagging of the
work material is restricted by the restriction portion 141 of the restriction member
140 by the action of the compression coil springs 151. Accordingly, a non-uniform
formation of thread loops and an occurrence of skipped stitches are prevented under
a condition where the presser foot 101 is moved up on the stepped portion 110.
[0108] Fig. 21 shows a condition where the stepped portion 110 is moved to a contact position
with the front inclined portion 123 of the presser foot 101. In this condition, an
upper corner of the stepped portion 110 is in contact with the front inclined portion
123 of the main body 120 and the restriction member 140 is further rotated by the
action of the compression coil springs 151 to prevent flagging of the work material
by the restriction portion 141 accordingly. At this time, the restriction portion
141 of the restriction member 140 fully protrudes downward from the bottom face 121
of the main body 120 of the presser foot 101. When a protrusion amount of the restriction
portion 141 is excessively large, the restriction portion 141 may interfere with the
sewing needle 106. The rotation restriction pins 142 are arranged at the restriction
member 140. The rotation restriction pins 142 adjust the protrusion amount in contact
with the restriction surface 127 arranged on the main body 120 of the presser foot
101 in order to prevent the interference between the restriction portion 141 and the
sewing needle 106.
[0109] Fig. 22 shows a condition where the stepped portion 110 of the work material is further
fed close to the rotary pin 104. In this condition, lower portions 153 of the lateral
faces of the restriction member 140 move along the stepped portion 110; thereby the
restriction member 140 is rotated around the shafts 143 in the counterclockwise direction
and the restriction portion 141 is accommodated in the accommodating portion 128 of
the main body 120. At this time, an inclination α of the presser foot 101 is reduced
by approximately 40 percent as compared with the inclination β of the known presser
foot 60 (see Fig. 34). Further, a height h1 of the rotary pin 104 from the work material
is shorter by approximately 10 percent as compared with the height h2 of the rotary
pin 4 of the known presser foot 60. Accordingly, a resistive force (acting in the
opposite direction from the feed direction) of the rotary pin 104 relative to the
work material, which occurs until the stepped portion 110 is moved directly below
the rotary pin 104 is reduced and variations of a load of the presser bar pressure
is reduced; thereby, the work material is smoothly fed under the presser foot 101.
[0110] Fig. 23 shows a condition where the stepped portion 110 of the work material is moved
directly below the rotary pin 104. In this condition, the presser bar pressure is
applied to a whole area of the front inclined portion 123 of the main body 120. Since
the virtual deepest portion 125a that is an inflexion point between the front inclined
portion 123 and the rear inclined portion 124 of the main body 120 is located further
rearward than the rotary pin 104, the condition shown in Fig. 23 is realized due to
the principle of leverage.
[0111] Fig. 24 shows a condition where the stepped portion 110 of the work material passes
right below the rotary pin 104. In this condition, the upper corner of the stepped
portion 110 is in contact with the rear inclined portion 124 of the main body 120.
At this time, the height of the rotary pin 104 varies but an amount of the variation
is small; therefore, feeding of the work material is not inhibited.
[0112] Fig. 25 shows a condition where the rear flat portion 122b of the main body 120 is
moved down from the stepped portion 110 of the work material. The presser foot 101
is moved down from the stepped portion 110 while flagging of the work material in
the space 111 having the approximately triangular shape formed between the stepped
portion 110 and the main body 120 is restricted by the restriction portion 141 of
the restriction member 140. Accordingly, when the work material is backstitched (reversely
fed) under such condition shown in Fig. 25, a rear end portion 155 of the restriction
member 140 enables the presser foot 101 to be easily moved up on the stepped portion
110.
[0113] Fig. 26 shows a condition where a rear end inclined portion 129 of the main body
120 of the presser foot 101 is in contact with the stepped portion 110 of the work
material. The known presser foot 60 illustrated in Fig. 32 does not securely press
the work material because the downwardly inclined angle of the known presser foot
60 is not sufficient due to interference between a contact portion 2a of the presser
holder 2 and the presser foot 60 as shown in Fig. 35. For example, when the feed dogs
move lower than the needle plate surface, the stepped portion 10 is suddenly or forcibly
moved in the feed direction by the rear end inclined portion 69 of the known presser
foot 60 by means of the presser bar pressure; therefore, the feed amount of the work
material is increased. As a result, the sewing needle 6 may be bent by the work material
forcibly moved in the feed direction.
Meanwhile, according to the presser foot 101 described in the second embodiment, a
forwardly inclined angle of the main body 120 is increased by the receded portions
131 and 132 preventing the main body 120 from interfering with the contact portion
105 of the presser holder 102 arranged at the main body 120. Further, the work material
is held by the presser bar pressure applied to a curved guide portion 154 (Fig. 16B
and Fig. 16D) of the main body 120. As a result, the work material is inhibited from
being forcefully fed in the feed direction.
[0114] Fig. 27 shows a condition after the presser foot 101 is moved down from the stepped
portion 110 of the work material. In this condition, the work material is pressed
by the restriction member 140 so that the portion of the work material around the
needle receiving hole 133 is pressed by the front flat portion 122a, the rear flat
portion 122b, and the restriction portion 141. Such condition is similarly seen in
the case of sewing the thin work material. Thus, the portion of the thin work material
around the needle receiving hole 133 is pressed by the front flat portion 122a, the
rear flat portion 122b, and the restriction portion 141 of the restriction member
140, therefore preventing skipped stitches.
[0115] According to the press foot 101 of the second embodiment, the restriction member
140 is provided with the protruding portion 141 protruding downward from the bottom
face 121 of the main body 120. Accordingly, when the stepped portion 110 is moved
to a contact position with a front portion of the presser foot 101, the space 111
having the approximately triangular shape is formed between the stepped portion 110
and the presser foot 101. At this time, the restriction portion 141 presses the work
material to thereby restrict the movement of the work material. Accordingly, thread
loops are uniformly formed and skipped stitches are prevented. Such effect of the
restriction portion 141 is seen when the presser foot 101 is moved up on and down
from the stepped portion 110. Further, the presser foot 101 is formed by four types
of components such as the main body 120, the restriction member 140 including the
restriction portion 141, the compression coil spring 151, and the torsion coil spring
152 and materials and a manufacturing process of the presser foot 101 are easily provided.
Furthermore, when the presser foot 101 is applied to the sewing machine, the body
of the sewing machine does not require the special configuration. Accordingly, the
presser foot 101 may be applicable to conventional sewing machines and optionally
provided thereto.
[0116] In addition, the restriction member 140 and the restriction portion 141 are integrally
molded with resin. Accordingly, the restriction member 140 is easily manufactured
at low cost and easily attached to the presser foot 101.
[0117] Moreover, the bottom face 121 of the main body 120 of the presser foot 101 is configured
so that the deepest portion 125a between the front inclined portion 123 and the rear
inclined portion 124 is positioned further rearward than the rotary pin 104. Accordingly,
for example, in the case where the stepped portion of the thick work material is sewn
(in the case of hemming jeans), the inclination of the presser foot 101 when the presser
foot 101 is moved up on the stepped portion is decreased, therefore reducing the upward
movement of the rotary pin 104 transmitting the presser bar pressure to the work material.
Further, even when the stepped portion 110 is inserted directly under the rotary pin
104, the rotary pin 104 does not necessarily move upward so as to be higher than the
thickness of the stepped portion 110 of the work material and the work material is
smoothly fed under the presser foot 101. Furthermore, the inclination of the presser
foot 101 allows the stepped portion 110 to be pressed along shapes of the front inclined
portion 123 and the rear inclined portion 124. Accordingly, a rear portion of the
bottom face 121, which is located further rearward than the rotary pin 104 is easily
moved up on the stepped portion 110. The upward movement of the rotary pin 104 gently
varies; thereby, the presser foot 101 is easily moved up on and down from the stepped
portion 110. The front inclined portion 123 and the rear inclined portion 124 are
formed so as to extend to the needle receiving hole 133. Accordingly, in the case
of sewing the thin work material, the portion of the thin work material around the
needle receiving hole 133 may not be pressed by the main body 120 of the presser foot
101. However, the main body 120 is combined with the restriction member 140; thereby
the portion of the thin work material around the needle receiving hole 133 is pressed
by the restriction member 140 to inhibit skipped stitches accordingly.
[0118] Fig. 28A and Fig. 28B illustrate a third embodiment that is a modified example of
the presser foot 101 according to the second embodiment. The presser foot 101 shown
in Fig. 28A and Fig. 28B includes the restriction member 140 to which a supplementary
restriction member 158 is attached. The supplementary restriction member 158 has arm
portions 158a and 158b positioned in the needle receiving hole 133 along the feed
direction. Fig. 28A and Fig. 28B are top and lateral views, respectively, of the presser
foot 101 according to the third embodiment.
Fig. 29 shows a condition where a flat portion of the work material is sewn. Fig.
30 shows a condition where the presser foot 101 according to the third embodiment
is moved up on the stepped portion 110 of the work material. Fig. 31 shows a condition
where the presser foot 101 according to the third embodiment is moved down from the
stepped portion 110.
[0119] The supplementary restriction member 158 is attached to the restriction member 140
and thereby holds the work material in the needle receiving hole 133 along the feed
direction. Accordingly, flagging of the work material is prevented right before the
sewing needle 106 moves downward toward and into the needle receiving hole 133. As
a result, threat loops are uniformly and effectively formed.
[0120] The principles, preferred embodiment and mode of operation of the present invention
have been described in the foregoing specification. However, the invention which is
intended to be protected is not to be construed as limited to the particular embodiments
disclosed. Further, the embodiments described herein are to be regarded as illustrative
rather than restrictive. Variations and changes may be made by others, and equivalents
employed, without departing from the spirit of the present invention. Accordingly,
it is expressly intended that all such variations, changes and equivalents which fall
within the spirit and scope of the present invention as defined in the claims, be
embraced thereby.