US3028824A - Thread take-up mechanism for sewing machines - Google Patents

Description

' April 10, 1962 F. PA'RRY ETAL 3,028,824

THREAD TAKE-UP MECHANISM FOR SEWING MACHINES Filed 24, 1950 2 Sheets-Sheet 1 o a 38 3e 7 37 35 "r O i ii f H 4| 22 O I .1-|I O l @E 3 2 i i i 0 i I 55. i

Fig. I. 33

INVENTOR. FRANK PARRY m y DAVID W. MATCHETT. WITNESS April 1962 F. PARRY ET Al. 3,028,824

THREAD TAKE-UP MECHANISM FOR SEWING MACHINES Filed Feb. 24, 1960 2 Sheets-Sheet 2 Fig.2.

INVENTORS. FRANK PARRY AND R BY DAV/D W. MATCHETT. WITNESS Wi V L 2 3,028,824 THREAD TAKE-UP MECHANISM FOR SEWING MACHINES Frank Parry, Trumbull, and David W. Matchett, Devon,

Conn., assignors to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Filed Feb. 24, 1960, Ser. No. 10,707 3 Claims. (Cl. 112-241) This invention relates to sewing machine thread takeup mechanisms and, more particularly, to a novel and improved means for driving a crank actuated thread takeup lever which is constrained by an anchor link.

The non-uniform motion of the thread take-up lever, and the anchor link of this type of thread take-up mechanism gives rise to serious vibrational effects not only in the take-up linkage but also in the take-up drive shaft. Since the take-up lever, in mechanisms of this variety, is almost invariably drivingly connected with a crank at the free extremity of the armshaft at a point which is cantilevered beyond the shaft bearings, the prime forces required to drive the take-up as well as the vibrational forces derived therefrom cause serious stress concentrations, of which the net result is that of limiting the maximum speed of operation.

It is an object of this invention to provide a novel and improved drive for a crank actuated take-up mechanism in which auxiliary driving connections for the anchor link extend from a portion of the shaft which is not cantilevered beyond the shaft bearings. With this arrangement, the prime forces required in the cantilevered shaft portion and the vibrational forces incident thereto are appreciably reduced and as a consequence increased speeds of operation are permissible.

With the above and other objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which;

FIG. 1 represents a head-end elevational view of a sewing machine having the end cover plate of the bracket arm removed to expose the thread take-up mechanism in accordance with this invention,

FIG. 2 represents a top plan view of the sewing machine of FIG. 1 with the head-end portion of the bracket arm sectioned to expose the thread take-up mechanism, and

FIG. 3 is a cross-sectional view of the sewing machine bracket arm taken substantially along line 33 of FIG. 2.

Referring to the drawings, the sewing machine casing includes a bed 20 from which rises a standard 21 supporting a bracket arm 22 in spaced relation over the bed. An arm shaft 23 is journaled lengthwise in the bracket arm ina bearing 24 in the head-end of the bracket arm and a similar bearing 25 at the standard end of the bracket arm. The armshaft is adapted to be belt driven from a suitable source of power by way of a hand wheel pulley 26 fast on the armshaft outwardly of the bearing 25.

The armshaft is cantilevered beyond the bearing 24 at the head-end of the bracket arm and has secured on the cantilevered portion adjacent to the bearing a counterweight 27. Carried by the counterweight is a compound crank including a needle bar driving crank pin 28 and a take-up actuating crank pin 29.

Journaled on the needle bar driving crank pin 28 is a needle bar driving link 30 which is pivotally connected to a 'needle bar 31 journalled for endwise reciprocatory motion in bushings 32 in the bracket arm. A thread carrying needle 33 is secured in the lower extremity of the needle bar.

Journaled on the take-up actuating crank pin 29 is one extremity of a thread take-up lever 34 which is formed at the other extremity with a thread eyelet 35.

States Patent f ice 3,028,824 Patented Apr. 10, 1962 anchor link-38 which is fast on a fulcrum pin 39 journaled in the bracket arm 22 substantially parallel to the armshaft.

The motion which is imparted to the thread take-up lever by the take-up actuating crank is controlled not only by the take-up crank is controlled not only by the throw of the crank 29 but also by the geometry of the thread take-up lever and of the anchor link; that is; by the relative distances between the take-up actuating crank pin 29 and the pin 37 connecting the take-up lever with the anchor link, and the distance between the pin 37 and the anchor link fulcrum pin. .The resulting motion at the thread eyelet 35 is a flattened orbital motion in a generally vertical direction toward and away from a thread guide 40 about which a thread passes following its emergence from a tension device 41. The thread to be taken up is directed from the thread guide 40 through the thread eyelet 35 on the take-up lever and then either directly or through suitable thread guides (not shown) to the thread carrying needle 33.

The motion of the anchor link 38 is a purely oscillatory motion about the axis of the fulcrum pin 39. In prior take-up mechanisms of this type, the prime forces necessary to drive the entire take-up mechanism had to be transmitted through the cantilevered take-up actuating crank pin 29. By prime forces is meant those forces necessary to accelerate and decelerate the thread take-up lever and the anchor link as well as forces necessary to overcome friction between relatively moving parts thereon. v

In accordance with the objects of this invention to minimize the prime forces required to be transmitted by the take-up actuating crank 29, the drive for the anchor link is assumed by an auxiliary crank 50 formed on the arm shaft 23 along a portion of the shaft at the opposite side of the shaft bearing 24 from the take-up actuating crank. \As illustrated in FIG. 2 of the drawings, the auxiliary crank is preferably arranged between the bearings 24 and 25. A connecting link 51 embraces the auxiliary crank 50 and is pivotally connected by a pin 52 to a rock arm 53 fast on the anchor link fulcrum pin 39 Although any drive means, such as for instance a cam means, may be used between the armshaft 23 and the fulcrum pin 39 which will impart to the anchor link precisely that oscillatory motion dictated by the take-up actuating crank pin and the geometry of the anchor link and the thread take-up lever, the preferred embodiment as shown in the drawings illustrates a construction in which the throw of the auxiliary crank 50 equals that of the take-up actuating crank and in which the geometry of the rock arm 53 and the connecting link 51 is identical with the geometry of the anchor link 38 and the thread take-up lever 34. This arrangement obviates any interference between the motions generated by the cranks 29 and 50.

Since the prime forces necessary to drive the thread take u-p mechanism are thus divided between the cranks 29 and 50, the resulting vibrational forces incident thereto are not concentrated at the unfavorable location of the cantilevered take-up actuating crank 29 as heretofore. As a result, a diminution of vibrational forces as well as a more favorable distribution of these forces is attained with which higher sewing speeds are obtainable.

Having thus set forth the nature of this invention, what we claim herein is:

1. A needle thread take-up mechanism for a sewing machine having a casing, a bearing carried in said casing, and a shaft journaled in said bearing, a take-up actuating crank carried by said shaft at one side of said bearing, a thread take-up lever journaled on said take-up actuating crank, an oscillatory anchor link, means pivotally supporting said anchor link on said casing, a pivotal connection between said anchor link and said thread takeup lever, the oscillatory motion of said anchor link being dictated by the motion of said take-up actuating crank and the geometry of said anchor link and said thread take-up lever, and means drivingly connecting said anchor link with a portion of said shaft at the opposite side of said hearing from said take-up actuating crank for imparting to said anchor link that oscillatory motion dictated by said takeup actuating crank and the geometry of said anchor link and thread take-up lever.

2. A needle thread take-up mechanism as set forth in claim 1 in which the means pivotally supporting said anchor link on said casing comprises a fulcrum pin journaled in the casing parallel to the shaft, and means for securing said anchor link fast on said fulcrum pin, and in which the means drivingly connecting said anchor link with a portion of said shaft comprises a rock arm fast on said fulcrum pin, an auxiliary crank carried on said shaft at the opposite side of said bearing from said take-up actuating crank, and a connecting link pivotally interconnecting said auxiliary crank with said rock arm.

3. A needle thread take-up mechanism as set forth in claim 2 in which the throw of said auxiliary crank equals that of said take-up actuating crank and in which the geometry of said rock arm and said connecting link is identical with the geometry of said anchor link and said thread takc up lever.

References Cited in the file of this patent UNITED STATES PATENTS 1,583,925 Hemleb May 11, 1926 2,120,127 Fleckenstein et al June 7, 1938 2,549,562 Baker Apr. 17, 1951 2,837,008 Erban June 3, 1958 FOREIGN PATENTS 813,226 Great Britain May 13, 1959

Images