US3215105A

US3215105A - Rotary hook for sewing machines

Info

Publication number: US3215105A
Application number: US307684A
Authority: US
Inventors: Ludwig J Kuhar
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1963-09-09
Filing date: 1963-09-09
Publication date: 1965-11-02
Anticipated expiration: 1982-11-02
Also published as: GB1008179A

Description

Nov. 2, 1965 L. J. KUHAR 3,215,105

ROTARY HOOK FOR SEWING MACHINES Filed Sept. 9, 1963 Fig. 3

INVENTOR.

WITNESS Ludwig J. Kuhur BY fla -Q34 "Bk (3 in! X TTORNEY United States Patent 3,215,105 ROTARY HOOK FOR SEWING MACHINES Ludwig J. Kuhar, Clark, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Sept. 9, 1963, Ser. No. 307,684 Claims. (Cl. 112-228) This invention relates to rotary hooks for sewing machines and more particularly to an improved needle guard for such rotary hooks.

This invention is a further development of the invention forming the subject matter of the copending United States application of Ketterer Serial No. 169,412 filed January 29, 1962 now Patent No. 3,120,204. That invention, as well as the one of the present application provide, inter alia, improved needle guards for rotary hooks.

When a rotary hook is secured to the hook shaft of a sewing machine, it must be adjusted so that its loop seizing beak will engage the needle thread loop when the needle is in a particular position. This adjustment is usually made by changing the angular relationship of the rotary hook and the shaft. As the needle guard is fastened to the hook, this adjustment unfortunately causes the needle guard to change its position relatively to the needle. It is desirable that the needle guard be so secured to the hook that it may be accurately adjusted relatively to the needle irrespective to the relative position of the rotary hook and hook shaft.

The importance of the needle guard adjustment can be understood from the fact that when seizure by the rotary hook of the thread-loop presented by the needle takes place, the needle has started its upstroke and thus the needle is moving vertically in a direction away from the rotary hook. By necessity, the needle guard at loop seiz ing time is located vertically below the loop-seizing beak on the rotary hook and guards the needle through contact with it below the eye of the needle and very near the upper end of the taper of the needle. The taper of the many types of needles used in sewing machines has different configurations depending upon the material being stitched (leather, cloth, etc.). The presence of the different tapers and different diameter needles, coupled with the fact that when maximum needle guarding is necessary the needle is moving in a direction away from the hook, makes it very desirable to provide a needle guard having capacity whereby it can be very accurately adjusted to function with the desired rotary hook timing and with the particular needle chosen for the material to be stitched.

It is therefore an object of this invention to provide a rotary hook with a needle guard which is adjustable both axially of and circumferentially about the hook shaft thereby to accommodate needles of various sizes and permit positioning the needle guard with respect to the loop seizing beak.

Other objects and purposes of this invention, will be evident from the following description, claims and drawings which describe and illustrate one embodiment of the present invention.

In the drawings:

FIG. 1 is a fragmentary perspective view of a sewing machine rotary hook embodying the present invention.

FIG. 2 is a top plan view of the rotary hook shown in FIG. 1.

FIG. 3 is a fragmentary elevational view, partly in section, of the rotary hook and thread carrying needle, showing the hook beak in loop seizing position.

With further reference to the drawings, there is illustrated a sewing machine throat plate 1 which has a needle aperture 2 through which a needle 3 reciprocates. A needle thread T is threaded through the eye 4 of the needle 3. Beneath the throat plate 1 is a hook shaft 5 on 3,215,105 Patented Nov. 2, 1965 which is mounted a rotary hook, indicated generally at 6, which cooperates with the needle 3 to form lock stitches. The hook 6, which is generally of conventional configuration includes a cup shaped hook body 7 and a hub 8 that is secured by set screw 9 to the shaft 5. The hook body 7 is formed with a loop seizing beak 10 that terminates in a loop seizing point 11. Upon rotation of the hook shaft, the hook 6 is rotated about the axis of the shaft 5 and the loop seizing point 11 moves in a circular path of travel defining a plane normal to the axis of the hook shaft 5. The needle 3 defines a needle path relatively to the hook 6 and the hook 6 is arranged to one side of and closely adjacent to the plane defined by the path of travel of the loop seizing point 11.

Within the hook body 7 is journaled a bobbin carrier 14, which is held in the hook body by a gib 15 secured by screws 16 to the periphery of the hook body 7. The bobbin carrier 14 is held against rotation with the hook body 7 by a rotation restraining finger 17. A thread guard 18 is secured to the periphery of the hook body 7 by screws 19.

The gib 15 has a flange 20 which is spaced from the plane defined by the path of travel of the loop seizing point 11 and disposed on the side of the plane opposite from the needle 3. This spacing is to provide clearance for the needle 3 as it descends into cooperation with the hook. After reaching its point of maximum penetration, the needle begins to rise, and as it does, it throws a loop of thread which is then entered by the loop seizing point 11. To insure loop seizure, the point 11 must pass immediately adjacent to the needle 3. However the needle may be bent or may be deflected so that, during operation, it may be positioned in the path of travel of the point 11 and thus struck by it, in which case it would of course become further bent or broken and also may damage the point 11. To avoid this, a needle guard 25 is provided which is adapted to engage the needle 3 during the time when the point 11 is passing adjacent to the needle 3 at a point immediately below the eye 4 and to position the needle closely adjacent to but out of the path of travel of the point 11.

The needle guard adjustment-means include a support element 26 which has a flat portion 27 in which is an elongated aperture 28 disposed substantially parallel to the hook shaft 5. Extending through the aperture 28 and threadedly engaged in the hub 8 is a screw 29 which secures the support element 26 to the hook 6. The screw 29 may be loosened so as to permit the support element to be moved in a direction perpendicular to the plane defined by the path of point 11 or, in other words, in a direction axially of the hook shaft 5.

The support element 26 has a raised portion 30 on which is a tongue 31 and mounted on the support element is the needle guard 25. The needle guard 25 has a block portion 33 which has a slot or groove 34 in its bottom. The tongue 31 is fitted within the groove 34 when the needle guard 25 is mounted on the support element 26. The needle guard 25 is secured to the support element 26 by screws 35 which extend through an elongated aperture 36 which is substantially perpendicular to the aperture 28. The support element 26 is limited in one direction of its adjustment relatively to the hook by the side 38 of the block portion 33 engaging the rearmost wall 39 of the hook body 7.

The needle guard 25 has a concaved surface 40 which provides clearance permitting the usual needle thread loop to be formed. At the end of the concaved surface 40 there is formed a needle positioning surface 41. So that no appreciable impact may be imparted to the back limb of the needle thread loop by the needle guard, the gib 15 is provided with a thread deflecting surface 42.

A loop controlling tail 45 is made integral with the needle guard 25 to control the thread-loop as it is withdrawn from the hook and the angle of the tail 45 is made obtuse to encourage the thread loop off the tail on needle guard.

When making the previously mentioned adjustment so as to accommodate needles of various sizes the screw 29 is loosened sufliciently to allow the support element 26 and associated needle guard 25 to be moved toward and away from the needle path. When the adjustment is satisfactorily made, the screw 29 is tightened to secure the needle guard with the hook.

When making the previously mentioned adjustment which causes the needle positioning surface 91 to engage the needle at the proper point in its stroke and at the time the loop seizing beak is passing the needle 11, screws 35 are loosened sufiiciently to allow the needle guard to be moved in a direction perpendicular to the needle path. When the adjustment is satisfactorily made, the screws 35 are then tightened to secure the needle guard with the hook.

Having thus described the nature of this invention, what I claim herein is:

1. In a rotary hook for sewing machines a hook body, a loop seizing beak secured thereto for rotation therewith and including a loop seizing point which point has a circular path of travel defining a plane normal to the axis of rotation of said hook body, a needle guard secured with said hook body for rotation therewith and including a needle positioning surface .for engaging a needle and positioning it relatively to said loop seizing point and means permitting adjustment of said needle guard in a direction perpendicular to said plane.

2. In a rotary hook for sewing machines a hook body, a loop seizing beak secured thereto for rotation therewith and including a loop seizing point which point has a circular path of travel defining a plane normal to the axis of rotation of said hook body, a needle guard secured with said hook for rotation therewith and including a needle positioning surface for engaging a needle and positioning it relatively to said loop seizing point and fastening means for securing said needle guard with said hook, said fastening means including means for adjusting said needle guard in a direction parallel to said plane.

3. The invention as defined in claim 2 and including means permitting adjustment of said needle guard in a direction perpendicular to said plane.

4. In a rotary hook for sewing machines a hook body, a loop seizing beak secured thereto for rotation therewith and including a loop seizing point which point has a circular path of travel defining a plane normal to the axis of rotation of said hook body, a needle guard secured with said hook body for rotation therewith and including a needle positioning surface for engaging a needle and positioning it relative to said loop seizing point, a support element, said needle guard being adjustably secured to said element and said element being adjustably secured to said hook.

5. A loop taker for a sewing machine including a loop seizing point, a needle guard having a needle positioning surface, fastening means for securing said needle guard on said loop taker with said needle positioning surface disposed adjacent said loop seizing point, said fastening means including means for adjusting said needle positioning surface relatively to said loop taker and said loop seizing point.

References Cited by the Examiner UNITED STATES PATENTS 2,019,284 10/35 Wesson 112-228' JORDAN FRANKLIN, Primary Examiner.

Claims

1. IN A ROTARY HOOK FOR SEWING MACHINES A HOOK BODY, A LOOP SEIZING BEAK SECURED THERETO FOR ROTATION THEREWITH AND INCLUDING A LOOP SEIZING POINT WHICH POINT HAS A CIRCULAR PATH OF TRAVEL DEFINING A PLANE NORMAL TO THE AXIS OF ROTATION OF SAID HOOK BODY, A NEEDLE GUARD SECURED WITH SAID HOOK BODY FOR ROTATION THEREWITH AND INCLUDING A NEEDLE POSITIONING SURFACE FOR ENGAGIONG A NEEDLE AND POSITIONING IT RELATIVELY TO SAID LOOP SEIZING POING AND MEANS PERMITTING ADJUSTMENT OF SAID NEEDLE GUARD IN A DIRECTION PERPENDICULAR TO SAID PLANE.