U.S. patent number 3,837,306 [Application Number 05/344,608] was granted by the patent office on 1974-09-24 for portable lightweight hand-held sewing machine.
Invention is credited to John S. Doyel.
United States Patent |
3,837,306 |
Doyel |
September 24, 1974 |
PORTABLE LIGHTWEIGHT HAND-HELD SEWING MACHINE
Abstract
A portable, lightweight, hand-held, chainstitching sewing
machine having: a reliable and inexpensive device for raising and
locking the presser foot carrier rod; a pivoted spool spindle
moveable between a storage position in which it is nearly flush
with a side wall of the sewing machine housing and a working
position in which it extends perpendicularly away from that wall; a
uniquely shaped feed dog cooperating with the needle and with the
hook to facilitate loop forming; a uniquely shaped hook providing
reliable loop forming; and a needle support biased to a position
facilitating loop forming.
Inventors: |
Doyel; John S. (New York,
NY) |
Family
ID: |
26964027 |
Appl.
No.: |
05/344,608 |
Filed: |
March 26, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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286719 |
Sep 6, 1972 |
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Current U.S.
Class: |
112/169;
112/324 |
Current CPC
Class: |
D05B
81/00 (20130101) |
Current International
Class: |
D05B
81/00 (20060101); D05b 001/00 (); D05b
027/02 () |
Field of
Search: |
;112/169,199,197,166,165,237,218R,218A,215,216 ;223/102,104 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Boler; James R.
Parent Case Text
CROSS-REFERENCES TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. Pat. application
Ser. No. 286,719 filed on Sept. 6, 1972 by the same inventor now
abandoned in favor of the subject continuation-in-part part patent
application.
Claims
I claim:
1. A portable lightweight hand-held sewing machine comprising a
housing having a handle adapted to be hand-held, having a base
portion, and having an upper portion disposed over the base portion
and spaced therefrom, with both the base portion and the upper
portion spaced from the handle, said base portion of the housing
including a horizontal upwardly facing throat plate, said upper
portion of the housing including: a downwardly facing plate having
an aperture therein, said downwardly facing plate further having a
lip extending forwardly of the aperture and a back portion
extending backwardly of the aperture, a vertical presser foot
carrier rod extending through said aperture and having a lower
portion disposed intermediate the downwardly facing plate and the
throat plate, a presser foot depending from the lower end of the
rod, said rod having an upper portion extending above the
downwardly facing plate and having a vertically extending slot
aperture with an upper wall, means for supporting the presser foot
carrier rod for reciprocating vertical movement, spring means for
urging the presser foot toward a working position against the
throat plate; and means for raising the presser foot carrier rod to
a nonworking position and for locking it in the nonworking
position, comprising: a raising and locking pin having a shank
slidably and pivotally received in and extending through the slot
aperture in the upper portion of the presser foot carrier rod and
disposed intermediate the upper wall of the slot aperture and the
downwardly facing plate, said shank having a back portion extending
backwardly of the rod over the back portion of the downwardly
facing plate and a forward portion extending forwardly of the plate
lip when the presser foot is in its working position, said raising
and locking pin further having a head comprising a downwardly
extending lock foot clearing the plate lip and extending downwardly
thereof when the presser foot is in its working position, said
raising and locking pin moveable vertically to move therewith the
presser foot carrier rod upwardly from the presser foot working
position to the nonworking position and to move the pin lock foot
to a position in which it is above the lip of the downwardly facing
plate, said pin additionally moveable backwardly within the presser
foot carrier rod slot aperture until the pin lock foot is over said
lip to lock therewith when released, with the spring means urging
the presser foot carrier rod downwardly, and with the upper wall of
the slot aperture in the rod pressing downwardly against the pin
shank and thereby pressing the lock foot against the plate lip.
2. A sewing machine as in claim 1 including a side wall of the
housing having a side facing opening, a spool spindle having a stem
extending outwardly of the housing through said opening therein and
having an anchor back portion disposed inwardly of the side wall,
means for pivotally supporting the anchor portion of the spindle to
allow pivoting the spindle between a storage position in which the
spindle stem is adjacent and substantially parallel with a portion
of the side wall and a working position in which the spindle stem
extends outwardly of the housing side wall and is substantially
perpendicular to a portion thereof.
3. A lightweight, hand-held, chain stitching sewing machine
comprising:
a housing including an upwardly facing work support surface having
means defining a needle aperture and a feed dog aperture in the
work support surface;
a thread carrying eyed needle and needle support means secured to
the housing for endwise reciprocation of the needle along a
vertical path through the needle aperture;
a loop taking hook and hook support means secured to the housing
for periodic movement of the hook along a defined path below the
work support surface;
means for feeding a work fabric along the work support surface and
over the needle aperture in a defined direction transverse to the
needle path, said feeding means including a feed dog having a
fabric engaging portion which protrudes at least intermittently
upwardly through said feed dog aperture in the work support surface
and a wall portion located below the work support surface adjacent
and facing the needle path, said wall portion having means for
engaging thread loops extending thereto and coming into contact
therewith, and feed dog support means secured to the housing for
periodic movement of the feed dog along a defined path;
means for driving the needle support means, the hook support means
and the feed dog support means in such timed relationship that
while the needle is moving up from the lowest position along its
vertical path, a thread loop forms and extends from the needle
toward said wall portion of the feed dog, as the needle continues
moving up the hook moves toward the needle and engages said loop,
and the feed dog and said wall portion thereof move, as the needle
moves up, in a direction opposite the direction in which the hook
moves to engage said loop, whereby said wall portion of the feed
dog tends to engage a loop extending towards it from the needle and
to move the loop toward the approaching hook to thereby facilitate
engagement of the loop by the hook.
4. A chain stitching sewing machine as in claim 3 wherein the means
for engaging thread loops comprise a loop assist projection affixed
to the wall portion of the feed dog and extending toward the
needle, said loop assist projection tending to engage successive
loops extending toward it from the needle and to move said loops
toward the hook for engagement thereby.
5. A chain stitching sewing machine as in claim 4 wherein the hook
includes a loop taking portion which is disposed between the needle
and said loop assist projection for at least a portion of the
periodic movement of the hook along the defined path.
6. A chain stitching sewing machine as in claim 5 wherein the loop
engaging porion of the hook terminates in a tip facing away from
the needle toward said wall portion of the feed dog, and wherein
the hook further includes a needle engaging portion which is
further away from said wall portion of the feed dog than the hook
tip and engages the needle for at least a portion of the periodic
movement of the hook along its defined path.
7. A chain stitching sewing machine as in claim 6 wherein the hook
intercepts the vertical path of the needle for at least a portion
of its periodic movement and deflects the needle tip from its
vertical path.
8. A chain stitching sewing machine as in claim 7 wherein the
needle support means comprises a stiffly resilient plate extending
away from the needle along a plane including the vertical path of
the needle, means for slidably supporting the plate within the
housing for vertical reciprocation of the plate, and biasing means
extending from the housing and engaging said plate to bias the
plate toward one side of its plane.
Description
BACKGROUND OF THE INVENTION
The invention relates to portable lightweight hand-held sewing
machines, and particularly to chain stitchers of the type disclosed
in U.S. Pats. Nos. 2,594,534; 2,637,288; 2,778,328; and 3,034,459.
In basic principles of operation, the sewing machine disclosed
herein is similar to the machine disclosed in U.S. Pat. No.
2,778,328.
Desirable characteristics of sewing machine of the type disclosed
herein are light weight, general simplicity of operation,
inexpensive construction and reliable operation. An object of the
subject invention therefore is to simplify, and enhance the
reliability of, certain aspects of lightweight, portable hand-held
sewing machines, and the subject invention concentrates
specifically on: means for raising and locking the presser foot
carrier rod; a spool spindle which can be conveniently moved to a
storage position in which it is nearly flush with a side wall of
the machine and can be moved therefrom to a working position in
which it extends perpendicularly away from that side wall; and a
feed dog, a loop taking hook and a biased needle support which
cooperate to facilitate loop forming.
SUMMARY OF THE INVENTION
An object of the invention is to provide a portable, hand-held
chain stitching sewing machine which is simple in construction and
in operation, which is inexpensive, and which provides reliable
service.
The machine disclosed herein comprises a housing having a handle
adapted to be hand-held, a base portion, and an upper portion
disposed over the base portion and spaced therefrom. The base
portion includes a horizontal upwardly facing throat plate serving
as a work support surface, and the upper portion includes a
downwardly facing plate which is over and spaced from the throat
plate. The upper portion of the housing supports for vertical
reciprocation a presser foot carrier rod which has a presser foot
at its lower end. A spring urges the presser foot downwardly toward
a working position in which it is pressed against the throat plate.
The presser foot can be raised to a nonworking position, in which
it is spaced from the throat plate to allow the insertion of work
fabric therebetween, by a pin received in an aperture within the
presser foot carrier rod and usable as a lever to raise the presser
foot and also as a lock to lock the presser foot in its raised
nonworking position.
The machine also includes a T-shaped spool spindle which has a stem
portion extending outwardly of the machine housing through an
opening in the side wall thereof, and an anchor portion pivotally
mounted within the housing. This arrangement allows the spindle to
be pivoted to a storage position in which it is nearly flush with
the housing side wall to minimize the overall dimensions of the
housing for easier storage. The spindle can be pivoted outwardly,
from the storage position to a working position in which it extends
nearly perpendicularly outwardly of the housing to allow for
conveniently mounting a spool thereon. The outward tip of the spool
spindle has a lock to retain a spool mounted on the spindle.
Reliable loop forming is facilitated by a device which tends to
push loops toward the loop taking hook, and by a hook which is
uniquely shaped.
In particular, the machine includes a feed dog moving in a periodic
motion along a defined path in a timed relationship with the
vertical reciprocation of the needle. The feed dog includes a loop
assist projection extending from the feed dog toward the needle in
the area where a loop is formed while the needle is moving up. The
motions of the needle, the feed dog and the hook are in such timed
relationship that while the needle is moving up from its lowest
position, a thread loop forms and extends from the needle toward
the wall of the feed dog which has the loop assist projection. As
the needle continues moving up the hook moves toward the needle and
engages the loop, while the feed dog and its loop assist projection
move in a direction opposite that of the hook to thereby tend to
push the loop toward the hook and to facilitate loop forming.
Loop forming is further facilitated by the unique shape of the hook
and its position with respect to the needle and with respect to the
feed dog.
In order to insure reciprocation of the needle along a well defined
and fixed vertical path without using high precision components,
the needle support is made of a stiffly resilient material and is
biased against the resiliency of the material to avoid any play
between components which may result in deviation of the needle from
a defined path.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of a portable hand-held sewing
machine embodying the invented features.
FIG. 2 is an enlarged side elevational view of the front portion of
the sewing machine shown in FIG. 1, when viewed from the side
opposite that shown in FIG. 1.
FIG. 3 is a perspective view of means for raising and locking the
presser foot carrier rod of the sewing machine shown in FIG. 1.
FIG. 4 is a sectional view along line 4--4 of FIG. 3.
FIG. 5 is a sectional view along line 5--5 of FIG. 1.
FIG. 6 is a sectional view along line 6--6 of FIG. 1.
FIG. 7 is a partly plan, partly broken front elevational view of
the sewing machine.
FIG. 8 is a detail of the view in FIG. 7 and shows a needle and a
needle support means in a position different from that in FIG.
7.
FIG. 9 is a partial sectional view taken along line 9--9 of FIG.
7.
FIG. 10 is a partial sectional view taken along line 10--10 of FIG.
7.
FIG. 11 is a partial sectional view of a detail of FIG. 7.
FIG. 12 is a sectional view taken along line 12--12 of FIG. 11.
FIG. 13 is a view similar to FIG. 11 but showing a different
position of the elements shown in FIG. 11.
FIG. 14 is a sectional view taken along line 14--14 of FIG. 13.
FIG. 15 is a sectional view taken along line 15--15 of FIG. 13.
FIG. 16 is a perspective partial view of a feed dog having a loop
assist projection.
FIGS. 17, 18, 19, 20 and 21 are partial sectional views of a detail
of FIG. 11 showing different stages of loop forming.
FIG. 22 is a partial sectional view similar to FIG. 15, but showing
several possible positions of a thread loop.
FIG. 23 is a partial sectional view along line 23--23 of FIG.
1.
DETAILED DESCRIPTION
Referring to FIG. 1, the sewing machine comprises a housing
including a handle 10 adapted to be hand-held, a body 12 enclosing
conventional components (not shown here) such as an electric motor,
batteries and driving gear, a base portion 14 topped by a
horizontal throat plate 16 which serves as a work support surface,
and an upper portion 18 disposed above the lower portion 14 and
spaced therefrom. The upper portion 18 includes a downwardly facing
plate 20 and an upper plate 22. The plates 20 and 22 have apertures
20a and 22a respectively (FIG. 2) which loosely receive a vertical
presser foot carrier rod 24. The presser foot carrier rod 24
terminates at its lower end in a presser foot 26. A coil spring 28
is disposed between the presser foot 26 and the downwardly facing
plate 20 and urges the presser foot 26 downwardly toward a working
position against the throat plate 16. The apertures 20a and 22a, in
the plates 20 and 22 respectively, provide a guideway for vertical
reciprocating motion of the presser foot carrier rod 24.
It is conventional to provide some means for moving the presser
foot carrier rod of a sewing machine in reciprocating vertical
motion between a working position thereof in which it is against
the throat plate and a nonworking position in which it is raised up
from the throat plate to allow the insertion of a work fabric
therebetween. In the subject invention, raising the presser foot
and locking it in the nonworking position is done by raising and
locking a pin 30 (FIG. 3) which consists of a backwardly extending
stem portion 30a and a forward head portion having a downwardly
extending lock foot 30b. The stem 38 of the pin 30 is loosely
received within a slot aperture 24a through the presser foot
carrier rod 24. As seen in FIG. 2, the stem 30a of the pin 30 is at
all times intermediate the upper wall of the slot aperture 24a and
the downwardly facing plate 20. A back portion of the stem 30a
extends backwardly of the carrier rod 24 and is over the portion of
the plate 20 which extends backwardly of the aperture 20a therein.
A forward portion of the pin 30 extends forwardly of the carrier
rod 24. When the presser foot is in its working position, the
forward portion of the stem 30a is above a lip 20b which forms the
front marginal end of the plate 20, and the lock foot 30b is in
front of the lip 20b and clears it.
To raise the presser foot 26 and to lock it in its nonworking
position, the pin 30 is moved from the solid line position shown in
FIG. 2 to the dotted line position shown therein. In particular,
the forward end of the pin 30 is grasped and lifted upwardly such
that the stem 30a of the pin 30 acts as a lever having as one arm
thereof the back portion of the stem 30a and as another arm thereof
the forward portion of the stem 30a. The stem 30a thus acts against
the upper wall of the slot aperture 24a in the carrier rod 24 and
lifts the carrier rod against the action of the spring 28. When the
forward end of the pin 30 is lifted sufficiently so that the lock
foot 30b is over the lip 20b and clears it, the pin 30 is pushed
backwardly to the dotted line position shown in FIG. 2. In that
position, the lock foot 30b is against the lip 20b and is pressed
against it by the force exerted on the stem 30a by means of the
spring 38 which pulls the carrier rod 24 downwardly.
In order to retain the stem 30a of the pin 30 within the slot
aperture 24a of the pressor foot carrier rod 24, the back end of
the stem 30a is provided with a resilient hook 30c (FIG. 4) which
allows insertion of the pin 30 into the slot aperture 24a of the
carrier rod 24, but prevents complete withdrawal of the pin 30 once
it is in place. The pin 30, as well as all other components shown
in FIGS. 1-5, except for the spring 28, are made of a plastic
material.
It is noted that the pin 30 also serves to hold the presser foot
rod 24 to the housing 14 and to guide it in its vertical
reciprocation; note that the stem 30a of the pin 30 extends between
walls 14g and 14h which are an integral part of the housing 14.
One of the requirements for lightweight hand-held portable sewing
machines of the type disclosed herein is compactness. For the
purpose of facilitating compactness, the sewing machine disclosed
herein is provided with a spool spindle which can be moved to a
storage position in which it is nearly flush with a side wall of
the sewing machine and thus minimizes the overall dimensions of the
sewing machine to allow storage thereof in a minimal size
container, and which is moveable from the storage position to a
working position in which it provides a convenient, simple and
reliable support for a spool of thread. Referring to FIG. 1, a
T-shaped spool spindle 32 having a stem 32a and a bar 32b at the
back end of the stem 32a is pivotally supported by the side wall
12a of the housing 12 which is opposite the side viewed in FIG. 1.
Referring to FIGS. 5 and 6, the bar 32b of the spool spindle is
inwardly of the side wall 12a, i.e., it is inside the housing 12,
and the stem 32a of the spindle 32 extends outwardly of the housing
12 through a suitable aperture 12b in the side wall 12a. The spool
spindle 32 is shown in FIG. 5 in solid lines in its storage
position and in dotted lines in its working position. It is seen
from FIGS. 1 and 5 that when the spool spindle 32 is in its storage
position, it is nearly flush with the side wall 12a of the housing
12. In particular, referring to FIG. 1, it is seen that the spool
spindle 32 is substantially within the opening below the handle 10
when it is in its storage position. When in its working position
(FIG. 5), the spool spindle 32 extends outwardly of the housing 12
and is substantially perpendicular to the shown portion of the side
wall 12a. Referring to FIGS. 5 and 6, the spool spindle 32 is
provided with spool locking means comprising a finger 32c which is
pivoted within the bifurcated forward end of the stem 32a by means
of a pivot pin 32d. As seen in FIG. 6, the finger 32c moves between
the solid line position so that a spool may be admitted on the
spool spindle 32, and the broken line position shown in FIG. 6 so
that the spool admitted on the spool spindle 32a may be locked in
place. The finger 32c is frictionally retained in either of its two
positions shown in FIG. 6. The bar portion 32b of the spindle 32 is
retained in its pivotally mounted positions by means of suitable
pins affixed to the housing 12. Two of these pins, namely pins 34a
and 34b, are shown in FIG. 6.
With respect to the position of the spool spindle 32, it is noted
that when in the storage position, the spool spindle stem 32a is
within the hand opening 10a below the handle 10, and that the
opening 10a is sufficiently large to accommodate a spool remaining
on the spindle 32 when the spindle is in a storage position.
The disclosed sewing machine is a chain stitcher and forms the
conventional chain stitch, which is briefly illustrated in FIGS. 17
through 21.
Referring to FIG. 7, a needle 34 is reciprocated along a defined
vertical path, and has a needle eye 34a carrying a thread 36. A
work fabric 38 is intermittently moved leftwardly by a feed dog 40
which moves along a defined periodic path in a defined timed
relationship wih the needle 34. Loops formed by the thread carrying
eye needle 34 below the work support surface 16 are engaged by a
hook 42 which is moved along a defined periodic path in a defined
timed relationship with the needle 34 and with the feed dog 40.
A typical chain stitch is illustrated in FIGS. 17 through 21, where
FIG. 17 shows the needle 34 in its up position and the hook 42
engaging a loop 36a. While the needle 34 is in its up position and
the hook 42 holds the loop 36a, the feed dog 40 moves the work
fabric 38 leftwardly. The needle 34 then comes down through the
fabric and through the loop 36a, as shown in FIG. 19. Specifically,
the needle tip strikes the forwardly and upwardly facing top
portion of the hook 42 and slides between the hook 42 and the
adjacent portion of the thread that forms the loop 36a. Once the
needle 34 has gone through the loop 36a, the hook 42 starts moving
leftwardly (as the needle 34 goes further downwardly), as shown in
FIG. 20, and releases the loop 36a. Once the loop 36a is released,
it is tightened as shown in FIG. 20 by the leftward motion of the
work fabric 38 and by the further downward motion of the needle 34.
The needle 34 then moves upwardly. As the needle 34 moves upwardly,
a loop 36b forms behind the needle and a loop 36c forms in front of
the needle. At that time the hook 42 is moving toward the needle
34, as shown in FIG. 21, and its tip 42a goes through the loop 36b,
i.e., between the thread forming the loop 36b and the lower part of
the needle 34, just above the needle eye 34a. As the hook 42
continues its motion to the right and the needle 34 continues its
motion upwardly, the hook and the needle come to the relative
positions shown in FIG. 17, and the cycle is repeated.
Referring to FIG. 22, it is seen that when the thread loop which
forms when the needle 34 moves up is on the side of the approaching
hook 42, the loop should be engaged by the hook, but that when the
loop points away from the approaching hook, it may be missed by the
hook. Thus, when the loop is similar to the loop 36d shown in FIG.
22, and points toward the approaching hook 42, there should be no
difficulty with the loop being engaged by the hook. Similarly,
there should be no difficulty when the loop points toward the
adjacent face of the feed dog 40, as the loop 36e in FIG. 22.
However, when the loop points away from the approaching hook 42, as
the loop 36f in FIG. 22, it may be impossible for the hook 42 to
engage the loop, with the result that a stitch may be missed. This
is particularly undesirable with chain stitching sewing machines,
and missed loops have long been a problem with chain stitchers.
In the sewing machine described here, special means are provided
for facilitating loop forming and loop taking, in order to reduce
substantially the possibility of missed loops. In particular,
referring to FIGS. 15, 16 and 22, the feed dog 40 includes a loop
assist projection 40a which tends to push the loops toward the
approaching hook 42, so as to ensure their engagement by the hook
42. Specifically, the purpose of the loop assist projection 40a is
to tend to prevent the formation of loops such as the loop 36f
shown in FIG. 22.
The operation of the chain stitching sewing machine described
herein is as follows. The throat plate 16 (FIGS. 7 and 9) which
serves as a work support surface is provided with a needle aperture
16a and a pair of feed dog apertures 16b and 16c which flank the
needle aperture 16a. The feed dog 40 comprises (FIG. 16) a pair of
vertical walls 40d and 40c which are spaced from each other and
face each other, and which have serrated upper portions that
protrude, at least intermittently, through the feed dog apertures
16d and 16c respectively (FIGS. 7 and 9). The loop assist
projection 40a extends from the side of the vertical wall 14b which
faces the needle 34 (FIGS. 15 and 16). The feed dog 40 includes a
back vertical wall 40e (FIG. 12) provided with a circular aperture
40f which receives an offset portion 44a of the shaft 44 which is
selectively rotated by a suitable motor (not shown) that can be
turned on and off by depressing and releasing a switch 46 (FIG. 1).
It is noted that the cam portion 44a of the shaft 44 is offset from
the center of the shaft 44 for reasons which will become apparent
in the description below. The main portion of the shaft 44 is
rotatably received within a suitable opening 48a in a vertical wall
48 which forms a part of the housing 14. The left-hand side of the
back wall 40e of the feed dog 40 terminates in a fork (FIG. 11)
whose opening 40g receives slidably the stem of a headed pin 50
extending forwardly from the wall 48. As the shaft 44 is rotated,
the feed dog 40 moves periodically along a path which is defined by
the offset of the shaft portion 44a from the center of the shaft 44
and by the sliding motion of the feed dog 40 with respect to the
pin 50.
The hook 42 is suitably secured to a support comprising a hollow
shaft 52 which is pivotally supported by a bolt 54 secured to the
wall 48, and is biased toward the wall 48 by a spring 56. The hook
42 is affixed to a vertical arm 52a (FIG. 11) which extends
upwardly from the shaft 52 and has a backwardly extending cam
follower projection 52b (FIG. 10) which cooperates with a cam
surface 44b formed integrally with the shaft 44, and another
backwardly extending cam follower projection 52c (FIG. 12) which
cooperates with a cam raceway 44c that also forms a part of the
shaft 44. The motion of the hook 42 is thus defined by the axis of
rotation of the shaft 52 and by the shape of the cam surface 44b
and of the cam raceway 44c, and by the positions of the cam
follower pins 52b and 52c.
The needle 34 is suitably secured to a needle shaft 58 (FIGS. 7, 8
and 23) which is formed integrally with a vertical plate 60
extending backwardly from the needle shaft 58 in the plane of the
vertical path of the needle 34. The plate 60 is received for
vertical reciprocation in a vertical slot 62a of a plate 62 which
forms a part of the housing 14. A transverse cam plate 64 is
integral with the plate 60 and is positioned just beyond the plate
62. The plate 64 forms a part of a conventional cam arrangement
cooperating with the driving shaft 44 to reciprocate the plate 60,
and hence the needle shaft 58 and the needle 34 along a vertical
path. The timing of the vertical reciprocation of the needle 34 is
thus defined by the cam connection between the plate 64 and the
driving shaft 44. Any other suitable means for vertical
reciprocation of the needle shaft 58 may be used, such as, for
example, the means for reciprocating the needle shaft shown in U.S.
Pat. No. 3,094,955 issued in 1963 to Fischbein et al.
The relative timing between the respective motions of the needle
34, the feed dog 40 and the hook 42 is such that when the needle 34
is in the lowest position of its vertical path (FIG. 13), the hook
42 is in its leftmost position and the right-hand side of the feed
dog 40 is in its lowest and rightmost position. As the needle 34
starts moving up, the tip 42a of the hook 42 starts moving towards
the needle, while the feed dog 40 remains substantially stationary.
When the hook 42 comes to about the position of FIG. 21, the
right-hand side of the feed dog 40 starts moving upwardly and
leftwardly while the needle 34 is moving up and the hook tip 42a is
moving rightwardly. It is noted that at this stage of the relative
motions between the needle 34, the feed dog 40, and the hook 42, a
thread loop 36a is formed and the loop assist projection 40a tends
to push that loop 36a towards the approaching tip 42a of the hook
42, to facilitate the engagement of that loop by the hook.
The needle 34 continues moving up, the hook 42 continues moving to
the right such that its tip 42a engages the thread loop 36a (FIG.
17) and the feed dog 40 continues its motion such that its
right-hand end moves leftwardly and upwardly. As the needle 34
moves up far enough to clear the work fabric 38, the upward and
leftward motion of the feed dog 40 accelerates, and the serrated
upper edges of the feed dog 40 engage the work fabric 38 and move
it leftwardly by a defined distance while the needle 34 is above
the work fabric 38. When the leftward motion of the feed dog 40 is
completed, the relative positions of the needle 34, the feed dog 40
and the hook 42 are as shown in FIG. 18. The needle 34 then starts
its downward path, and the right-hand side of the feed dog 40
starts moving downwardly and rightwardly while the hook 42 remains
for a while in the position shown in FIG. 18. With the hook 42
remaining in the position of FIG. 18, the tip of the needle 34
strikes the upper, forwardly facing surface of the hook 42 (FIGS.
15 and 19) and its point goes through the loop 36a which at this
time is being held by the hook 42 (FIG. 19). After the needle 34 is
through the loop 36a, the hook 42 starts pivoting leftwardly (FIG.
20) while the needle 34 continues downwardly and the right-hand
side of the feed dog 40 continues moving downwardly and
rightwardly.
In order to facilitate loop taking, the hook 42 has a uniquely
shaped upper portion. The upper portion of the hook 42 terminates
in a rightwardly pointing tip 42a, and the side of its upper
portion which faces the needle path is convex. Referring to FIGS.
12, 15 and 22, the upper portion of the hook 42 includes a face 42b
which faces forwardly and upwardly to engage the needle 34 and to
facilitate entry of the needle point into a formed looped (see FIG.
19). In its downward path, the tip of the needle 34 first strikes
the face 42b of the hook 42, just above the loop engaged thereby,
and is somewhat deflected forwardly from its vertical path by the
face 42b of the hook 42. Both the hook 42 and the needle 34 are
somewhat resilient, and both bend somewhat upon engagement with
each other: the needle bends outwardly, and the hook bends
inwardly. Meanwhile, the needle tip goes through the loop held by
the hook, as seen in FIG. 19, so that the loop can be retained by
the needle 34 after the hook 42 starts moving leftwardly, as shown
in FIG. 20.
In order to make sure that the hook 42 engages the loop 36b which
is behind the needle 34 (FIG. 21) rather than the loop 36c which is
forwardly of the needle 34, the tip 42a of the hook 42 points away
from the needle (FIGS. 12 and 15) toward the wall 40 of the feed
dog which has the loop assist projection 40a.
While it is desirable that the needle 34 reciprocate along a
strictly defined vertical path, so that it consistently engages in
the same manner with the hook 42, it is also desirable that the
needle support means utilize components which are not precision
parts, so that the cost of making the sewing machine can be
reduced. For the purpose of accommodating these conflicting goals,
the subject invention provides a needle support which is
resiliently biased such that it reciprocates the needle 34 along a
fixed vertical path in spite of possible substantial play between
components. Referring to FIGS. 1, 7, 8, and 23, the needle 34 is
suitably secured to a vertical needle bar 58, and the needle bar 58
is integrally formed with a backwardly extending vertical plate 60
whose back end is integrally formed with a transverse plate 64. The
plate 60 reciprocates vertically with the needle 34, and the
vertical reciprocation path is defined by means of the facing edges
62a of plates 62 which are integral with the machine housing 14.
The facing edges 62a of the plates 62 serve as key guides and fit
loosely within vertical key grooves 60a in the plate 60. The
assembly including the plates 64 and 60 and the needle rod 58 and
the needle 34 is reciprocated vertically by means of a suitable cam
(not shown) affixed to the shaft 44 and a suitable cam raceway (not
shown) forming a part of the plate 64.
When low precision components are used, there would normally be
considerable play between the key grooves 60a and the keys 62a
fitting therein. In order to ensure reciprocation of the needle 34
along a fixed vertical path in spite of this possible play, the
plate 60 is biased leftwardly by means of a bias cam 66 (FIG. 66)
which is carried by the housing 14 and whose left end slidably
engages the right side of the plate 60 and pushes the forward end
of the plate 60 leftwardly against the natural resiliency of the
plate 60, which is made of a stiffly resilient plastic material. In
this manner, any play is taken by the resilient biasing of the
plate 60, and the needle 34 is caused to reciprocate along a fixed
vertical path.
It is understood that orientation terms such as "horizontal",
"vertical", etc. are used merely for description convenience, and
relate to only one of the many possible positions of the sewing
machine disclosed here.
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