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Патент USA US3087398

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April 30, 1963
L. J. KUHAR
-
3,087,388
METHOD OF‘ FORMING A NOTCH IN A BOBBIN CASE CARRIER
Original Filed May 19, 1958
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26
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2
5
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INVENTOR.
Ludwig J. Kuhar
PRIPRART
F'g'3‘
By‘ [MW/5M
ATTORNEY
ice
United States Patent
2
1
on the top of the side wall 1, a laterally extending loop
3,087,388
controlling flange 7 that extends beyond the top‘ center
METHOD OF FORMING A NOTCH IN A BOBBIN
CASE CARRIER
Ludwig J. Kuhar, Clark, N.J., assignor to The Singer Man
of the carrier and at the top thereof is provided with a
notch 8 ‘for receiving the tongue of a rotation restraining
?nger (not shown). On the cast on side of the bobbin
case carrier, there is provided a bobbin thread guiding
slot 9. The rear face of the flange 7 at the top thereof
ufacturing Company, Elizabeth, N.J., a corporation of
New Jersey
Original application May 19, 1958, Ser. No. 736,160, now
Patent No. 3,046,922, dated July 31, 1962. Divided
and this application Aug. 2, 1961, Ser. No. 128,780
1 Claim. (CI. 90-11)
3,087,388
Patented Apr. 30, 1963
is milled away at 10[ and has a bore 11 to provide for
needle clearance.
I
This application is a division of application Serial No.
736,160, t?'led May 19, 1958 and now Patent No.
With reference to FIG. 3, there is illustrated a bobbin
case carrier construction in accordance with the prior art
methods and which includes I3. rotation restraining notch
3,046,922.
8a.
relatively to the bobbin case carrier. During ‘operation of
the sewing machine, the bobbin case carrier is restrained
against rotation while the hook is rotated relatively
the inner ends of the side walls 12 were flared or beveled
outwardly by means of relatively narrow cutters in the
10
In the prior construction, the rotation restraining
notch ‘8a was formed in three successive milling opera
The present invention relates to a bobbin case carrier
of a sewing machine and more particularly to the dorma 15 tions. In the ?rst operation, a slot is milled in the face
of the ?ange 7 by a relatively wide cutter that passes
tion of the rotation restraining notch in the bobbin case
straight across the face of the flange 7 substantially radi
carrier of a sewing machine.
ally of the bobbin case carrier, thus producing the side
In a lock stitch sewing machine ‘of the rotary hook
walls 12 and the bottom 13' of the notch ‘8a. To avoid
type, the bobbin is mounted in a bobbin case that is in
turn inserted in a bobbin case carrier which
mounted 20 the sharp corners of the inner end of the side walls 12
that result from the ?rst milling operation, over which
in the ‘body of the rotary hook for rotation of the hook
corners the thread is drawn during the sewing operation,
thereto to seize and cast a loop- of needle thread about 25 two subsequent milling operations. These cutters were
passed through the slot at an angle to the center line of the
the bobbin case carrier. Since the needle thread loop
must pass completely around the bobbin case carrier, the
slot, thus producing the side walls '14 and 15 and the re
spective bottoms 16 and 17.
rotation restraining means must allow for passage of the
Within the limitations of reasonably economical manu
thread between the rotation restraining means and the
bobbin case carrier. In the conventional manner, the ro 30 facturing processes, the cutters in the milling operations
cannot be held to exactly the same depths with the result
tation restraining means comprises a ?nger mounted in
that the bottoms 13», 16 and 17 do not coincide, or in
the bed of the machine and having a tongue that is seated
other words, do not de?ne a single continuous planar
in a notch in the face of the bobbin case carrier. This
bottom for the notch 81:. In FIG. 3, there is illustrated
invention relates speci?cally to the formation of this
rotation restraining notch in the bobbin case carrier and 35 the condition that results when the left hand cutter is set
at a depth ‘slightly less than the depth of the initial straight
has for an object to torm this notch in such a manner as
cutter and the right hand cutter is set at a depth slightly
to facilitate manut?acture.
greater than the depth of the initial cutter. In this case,
Having in mind the above and other objects that will
the bottom 16 is above the bottom 13' with a resulting
be evident from an understanding of this disclosure, the
invention comprises the devices, combinations and ar 40 edge 18 at the meeting line, and the bottom 17 is below
the bottom 13 and in effect cuts a groove in the bottom 13
rangements of parts as illustrated in the presently pre
ferred embodiment of the invention which is hereinafter
set forth in such detail as to enable those skilled in the art
readily to understand the function, operation, construc
tion and advantages of it when read in conjunction with
the accompanying drawings in which:
FIG. 1 is a plan View of a bobbin case carrier for a
rotary book of a sewing machine, which bobbin case car
which produces edges 19.
Since during the sewing operation, the limb of the
needle thread must be swung laterally across the notch 8a
before the loop is withdrawn, the bottom of the notch
8a must be smooth and continuous, or in other words,
without edges such as at 18 and 19 upon which the thread
could catch or snag and be thus held back. Thus, after
milling in the prior construction, the bottom of the notch
rier embodies the present invention.
50 8a had to be hand ?led to remove any edges, such as 18
'FIG. 2 is a fragmentary sectional view taken substan
and 19, resulting from the milling operations. Because
tially on the line 2-2 of FIG. 1,
the notch 8a is only less than one eighth of an inch wide
FIG. 3 is a fragmentary plan view similar to FIG. 1
and because the post 3 is located only three eighths of an
and illustrating the prior art.
The present invention is herein disclosed as applied to 55 inch trorn the inner edge of the side wall 1, this ?ling
‘operation is very delicate and di?icult. At the same time,
a bobbin case carrier of a conventional type of rotary
and also because of the variations in the resulting edges
hook which is illustrated, for example, in the United
in the bottom of the notch ‘So, this ?ling operation was
States patent of Kessler, No. 2,085,699, to which reference
performed by hand. It is obvious that ?nishing of the
may be had rfor an understanding of the function and op
bottom of the notch 81: was an expensive ‘operation.
eration of the bobbin case carrier.
In accordance with the present invention there has been
As illustrated in the drawings, the bobbin case carrier is
provided a bobbin case carrier in which the rotation
cup-shaped and comprises a cylindrical side wall 1 which,
restraining notch S is forrnedin such a manner as to elimi
to reduce the mass, has an ope-n back that is spanned by a
nate the subsequent hand ?ling that is required in the
diameter bar 2. The bar 2 supports a centrally located
prior art construction. As illustrated in FIGS. 1 and 2,
stud 3 for mounting and latching the bobbin case within
65 the notch '8 in the present construction comprises an outer
the carrier.
portion 20 in the form of a slot having parallel side walls
For journaling the bobbin case carrier within the race
21 and a planar bottom 22. The outer portion 20, like
way of a rotary book, there is provided a peripheral bear
the slot formed in the ?rst milling ‘operation in the prior
ing rib 4 on the outer surface of the side wall 1. The
bearing rib 4 is ‘discontinuous to provide a thread loop 70 art construction, is arranged substantially radially of the
bobbin case carrier. To ?are the inner ends of the slot
detaining shoulder 5- and a loop con?ning shoulder 6.
outwardly there is an inner portion 23 comprising a de
On the needle thread loop cast off side, there is provided
3,087,388
4
3
pression milled in the face of the ?ange 7 to substantially
the same depth as the outer portion 20‘ and having an inner
variations in the depth of penetration \of the end mill 27
from the designed optimum, while it may vary the posi
edge which is de?ned by the coinciding inner edges of the
tion of the line 26 radially of the bobbin case carrier or
side Wall 1 and ?ange 7 and an outer edge which is ar
ouate with a diameter greater than the width or" the 10111161‘
is thus crescent-shaped and intersects the side Walls 21
may produce an edge along the line 26, it does not pro
duce any appreciable edges lengthwise of the notch 8 upon
which the thread could snag as it moves laterally of the
notch 8.
Numerous alterations of the structure herein disclosed
of the ‘outer portion 20 to provide arcuate side edges 24
will suggest themselves to those skilled in the art.
portion 20 and ‘arranged substantially ‘centrally of the
center line ‘of the outer portion 20. The inner portion 23‘
How
which constitute diverging side walls and thus act to ?are 10 ever, it is to be understood that the present disclosure
‘relates to a preferred embodimentof my invention which
outwardly the inner ends of the side Walls 21 of the outer
is for purposes of illustration only and not to be con
portion 20. The inner portion 23‘ includes a bottom 25
strued as a limitation of the invention. All such modi
which, to avoid a sharp edge :at its meeting line with the
?cations which do not depart from the spirit of the in
bottont wall 22 is amanged at -a slight angle to the plane
of the bottom wall 22, the angle being illustrated at A in 15 vention are intended to be included Within the scope of
FIG. 2 and being substantially three degrees. Thus, the
the appended claim.
Having thus set forth the nature of the invention, what
bottom walls 22 ‘and 25 will ‘always intersect ‘along a line,
such as 26, and will blend smoothly.
In the {formation of the slot 8 in accordance with the
I claim herein is:
present invention, the ?rst operation is the same as in the
a sewing machine bobbin case carrier having a cylindrical
prior construction, -i.e., the ?ange 7 is ?rst milled by a
side Wall and a laterally extending ?ange on the top of
The method of forming a rotation restraining notch in
said side Wall, comprising the step of cutting a slot across
cutter that passes across the face thereof to provide ‘a slot
the face of said ?ange arranged generally radially of said
and thus form ‘the outer portion 20‘ of the notch 81. The
bobbin face carrier and having a planar bottom and par
slot is then ?ared, as illustrated in FIG. 2, by a circular
end mill 27 [having a diameter greater than the diameter 25 allel side Walls, and the step‘ of ?aring the inner ends of
said side Walls by a circular end cutter havinga diameter
of ‘the slot and advanced endwise onto said ?ange with
greater than the width of said slot and advanced endwise
the axis thereof arranged at an ‘angle ‘of three degrees
onto said ?ange at the \inner end of said slot at a slight
to a line normal to the bottom wall 22 to form- the inner
angle to a line normal to the bottom of said slot.
portion 23 of the notch =8. Thus, the notch 8 has been
completely formed in only two operations and Without
No references cited.
the necessity of a subsequent hand ?ling operation. Any
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