Needle clamp arrangement for a sewing machine

A device for holding a sewing needle which has a cylindrical shank, an arcuate portion, and a flat wall portion, in a needle bar which has a longitudinally extending receiving groove with a flat interior receiving wall comprising a locking member. The locking member has a longitudinally extending bridge part with outwardly extending arms engageable around at least a portion of the circumference of the needle bar. The arms include an upper abutment arm extending outwardly of said bridge portion into the needle bar groove and defining a stop against which the top of the needle bar is engageable. The construction includes a lower abutment arm extending outwardly from the bridge engageable with an arcuate end over the arcuate portion of the shank so as to hold the flat portion of the shank of the needle on the flat interior receiving wall of the groove.

FIELD AND BACKGROUND OF THE INVENTION 
This invention relates in general to sewing machines and in particular to a 
new and useful needle holder for a sewing machine which comprises a device 
for locking a needle shank in a groove of a needle bar. 
With the needle holder arrangements known until now there are difficulties 
in satisfactorily positioning the shank of the needle both in its height 
position and in its angular position. Usually several additional elements 
are necessary for this purpose, owing to which, besides expensive 
manufacture, further assembly costs arise. 
SUMMARY OF THE INVENTION 
To eliminate these disadvantages, the invention provides means for 
positioning the needle which are of uncomplicated design and easy to 
connect with the needle bar. 
In accordance with the invention a needle which has a cylindrical shank 
portion, a flattened edge which engages against a flattened interior wall 
of a longitudinal groove in the needle bar is accurately positioned within 
the groove by means of a locking device which includes a bridge having an 
upper and lower arm disc portion which engages around the periphy of the 
cylindrical needle bar and includes an upper arm having an abutment which 
extends into the groove of the needle bar and forms an upper stop against 
which the needle is positioned and an arm spaced downwardly from this arm 
which has a contoured or cylindrically face which engages around the 
arcuate surface of the needle bar and presses the needle bar so that the 
flat face will be against the wall. 
The device of the invention provides a locking element which may be used 
both for determining the height position of the needle relative to the bar 
as well as accurately oriented needle shank into the groove of the needle 
bar. The inventive arrangement of formed stable configuration and a secure 
attachment to the needle bar are achieved. The device for clamping the 
needle also includes a thread guide which is engaged with a bridge portion 
of the device and provides means for guiding the thread. 
Accordingly it is an object of the invention to provide an improved locking 
device for locking a needle in a receiving groove of a needle bar. 
A further object of the invention is to provide a device for positioning a 
needle shank in respect to a needle bar of a sewing machine which is 
simple in design, rugged in construction and economical to manufacture. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a pair 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its uses, reference 
is made to the accompanying drawings and descriptive matter in which a 
preferred embodiment of the invention is illustrated.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawing in particular the invention embodied therein 
comprises a device in the form of lock generally designated 16 for holding 
a sewing needle 4 which has a shank 3 with an arcuate portion 3a and a 
flat wall portion 3b in a longitudinal groove 2 of a needle bar 1 so that 
the flat side 3b engages against the flat interior wall of the groove and 
is positioned at a desirable location. In accordance with the invention, 
the locking device comprises a longitudinally extending bridge part 15 
having arm means in the form of discs 18 of an upper arm 14 and a lower 
arm 13 which engage around a substantial portion circularly cylindrical 
needle bar 1. The device 16 includes an upper abutment arm 19 which 
projects outwardly from the bridge portion and engages into the groove 2. 
The upper arm 19 describes a stop or abutment for the top of the needle 
shank portion 3. Another arm 20 formed with a cylindrical concave exterior 
surface 21 which engages against the arcuate surface 3a of the needle 
ensures that the flat surface 3b will be oriented against the flat 
interior wall of the longitudinal groove 2. 
As FIGS. 1 to 3 show, there is cut into the lower end of a needle bar 1 a 
longitudinal groove 2 which extends from a certain point of the needle bar 
1 to its lower end. This longitudinal groove 2 serves to receive a shank 3 
of a needle 4. Shank 3 is flattened on one side, so that the needle 4 can 
be inserted in its correct angular position also be an unskilled operator. 
At its lower end the needle bar 1 has a section 5 of smaller diameter. Onto 
this section 5, a needleblock 7 with a bore 6, is press-fitted in such a 
way that there results an annular transverse groove 8 between the upper 
end face of the needle block 7 and the portion of the needle bar 1 with 
normal diameter. 
The needle block 7 has a laterally extending tubular projection 9 with 
female thread for the threadable engagement of a clamping screw 10. The 
screw is pressed by its end against a clamping piece 1 lying in a recess 2 
which passes through the needle bar 1. 
The locking element 16 consisting of two parallel annular discs 13 and 14 
and the bridge piece 15 can be slipped onto the section 5 of the needle 
bar 1 over the needle block 7. The discs 13 and 14 comprise sprung arcuate 
arms 17, which are provided at their ends with inwardly directed lobes 18, 
the inner faces of which apply against the circumference of section 5. 
When being slipped onto section 5, the arms 17 of the upper disc 14 insert 
themselves additionally into the transverse groove 8. 
The upper disc 14 is further equipped with a flat abutment 19 which extends 
crosswise into the longitudinal groove 2 and forms a stop for shank 3 of 
needle 4 upon insertion in the longitudinal groove 2. The lower disc 13 is 
provided with the arm 20 which likewise extends into the longitudinal 
groove 2. The free end of this arm 20 has a contour area 21 adapted to the 
diameter of shank 3 of needle 4, which contour area together with the 
inner wall of the longitudinal groove 2 leaves a free passage adapted to 
the cross section of shank 3. Therefore, shank 3 of needle 4 is insertable 
into the longitudinal groove 2 only in the predetermined angular position. 
The bridge piece 15 of the locking element 16 is, after the latter has been 
slipped onto the needle bar 1, spaced from the front of the needle block 7 
in order to leave space for a cross piece 22 of a thread guiding element 
23. The thread guiding element 23 serves to receive a needle thread or two 
needle threads, one of which can then be threaded into right or left 
eyelet 24. The eyelets 24 are formed symmetrically on the cross piece 22. 
Their free ends apply against the needle block 7, while the ends connected 
with the cross piece 19 lie in a retention formed by lateral recesses 25 
of bridge piece 15. 
In FIG. 4, is shown a locking element 16' which comprises a bridge piece 
15' equipped with enlargements 26. The enlargements are separated upwardly 
from the bridge piece 15' by thread guiding slots 27. Here the needle 
threads are threaded simply into the slots 27. 
When inserting shank 3 of needle 4 into the longitudinal groove 2 of needle 
bar 1, shank 3 is inserted against abutment 19 in an angular position such 
that the flattened area at shank 3 applies against the inner wall of the 
longitudinal groove 2. The contour area 21 of arm 20 prevents the needle 4 
from being inserted in a wrong angular position. The clamping screw 10, 
when being screwed in, presses against the clamping piece 11, owing to 
which the latter locks between bore 6 in needle block 7 and shank 3 of the 
needle 4. Shank 3 is pressed against the inner wall of the longitudinal 
groove 2 and thus needle 4 is fixed in its position. 
While a specific embodiment of the invention has been shown and described 
in detail to illustrate the application of the principles of the 
invention, it will be understood that the invention may be embodied 
otherwise without departing from such principles.