US2532790A - Sewing machine - Google Patents

Description

B. A. SCHMITT SEWING MACHINE Dec. 5, 1950 Filed Aug. e, 1945 2 Sheets-Sheet l B. A. SCHMITT SEWING MACHINE Dec. 5,

, Filed Aug- 6' 1945 2 sheets-Shea'c 2 Patented Dec. 5, 1950 UNITED STATES PATENT OFFlCE 2,532,790 SEWING MACHINE Bernard A. Schmitt, Chicago, Ill. Application August 6, 1945, serial No. 609,115

3 Claims. (ol. 112-210) This invention relates to sewing machines, and more particularly to sewing machines of the household type adapted to be constructed and sold at low cost.

It is a general object of the present invention to provide a novel, improved and simplified household type sewing machine.

More particularly it is an object of the invention to provide, in a household sewing machine, improved low cost, fully balanced drive means between the main shaft and one or more shafts beneath the bed plate, and including a silent chain and sprockets.

An important object of the invention comprises means for imparting uniform driving motion to stitch-forming mechanism of the type including a two-to-one rotary hook operating on a vertical axis and including a silent chain drive between the main shaft and a parallel shuttle shaft beneath the bed plate, together with reducing spiral gear drive connections between the shuttle shaft and the vertical hook shaft.

Another object of the invention consists in the novel drive and stitch size adjusting mechanism for the feed point and including means for adjusting certain parts for initial t and to compensate for wear.

Among the important features of the invention may be enumerated the provision of stitchforming mechanism so arranged and positioned that the bobbin may be manipulated entirely with the right hand; the use of self-aligning bearings for the main and shuttle drive shafts; the use of tapered cams and eccentrics in the control and operation of the feed point whereby good initial fits may be established with less care in the machining and whereby adjustments for wear are facilitated; the use of spiral bevel gears to provide a two-to-one ratio of shuttle or hook speed to shuttle drive shaft speed, permitting the .shuttle drive shaft to directly actuate the feed point carrier to impart the vertical component of motion thereto; and the arrangement of novel mechanism for adjusting the length of stitch or fabric feed by means of simplified, low cost parts requiring the minimum of care andV attention.

Other and further objects and features of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specification wherein is disclosed a single exemplary embodiment of the invention, with the understanding that such modifications may be madetherein as fall within the scope of the appended claimsv In said drawings:

Fig. 1 is a front elevation of a sewing machine constructed in accordance with the present invention showing a portion of the frame and housing in section, with all of the working elements in elevation;

Fig. 2 is a bottom plan view thereof;

Fig. 3 is a left end elevation with the head cover removed;

Fig. 4 is a vertical section through the standard, taken in a plane at right angles to the main shaft and showingthe feed drive and stitch adjusting mechanism in maximum stitch position;

Fig. 5 is an enlarged view of the feed shaft drive mechanism and stitch adjusting means of Fig. 4, shown in minimum stitch position;

Fig. 6 is a section on line 6-6 of Fig. 5 showing the configuration of the working surface of the cam and cam follower;

Fig. '7 illustrates a modication of these surfaces; and

Fig. v8 is a fragmentary vertical section on line 8-8 of Fig. 3 showing the mounting of the feed point carrier on the feed shaft.

HouseholdV sewing machines as heretofore available have been relatively satisfactory in initial performance but have been unduly costly, cumbersome and heavy and have required too frequent and expensive servicing. Both the cost and the weight are accounted for by the necessity for complicated drive means, careful and accurate machining, and heavy, cumbersome parts, all necessitated by the design. The applicant finds that equally satisfactory sewing work can be done on asimplified and lightened machine where the` amount of intricate and delicate ma-V chine work is materially reduced without in any manner entailing a diminution of the quality of operation. lThe machine illustrated is intended for ordinary household use and may be driven either with the customary foot treadle or any suitable form of electric drive. All adjustments required to maintain it in operation over long periods of time can be made by the owner.

Referring now to the drawing, it will be seen that the machine is shown as of conventional style, including a bed plate l0, a hollow standard I2, a substantially horizontal arm I4 and a head I6. The main shaft I8 extends horizontally through the arm, into the head and through the standard, supporting on the outside the usual balance or hand wheel 20, which in the present case is intended to rotate in the direction of the ar row. This shaft is journalled at the junction of the head and arm in a bushing 22 and in the right hand wallof the standard in a bushing 24.

3 These bushings are slightly elliptical on their exterior surfaces and are received in cylindrical bores 25 where they are clamped by set screws 26. The shape of the bushings makes them selfaligning and materially reduces the care needed in boring the bushing receiving openings.

In the head I6 a counterbalanced double crank device 21 provides for driving the link 28 connected to the needle bar 29 and the link 30 for operating the thread takeup 3l. The head likewise houses the conventional presser foot rod 32 biased downwardly by spring 33 and adapted to be lifted manually by means of lever 34 equipped with suitable thread tension releasing means, not

shown.

The stitch-forming mechanism illustrated generally by the device 36 is not shown in detail but involves a hook or shuttle and a bobbin adapted to be rotated on a vertical axis. The shuttle carrier is mounted on vertical shaft 31, seen in dotted lines in Figs.. 1' and 3, and in plan in Fig. 2'.. This shaft is j'ournalledY in spaced bearings 38 extending from a boss 3S secured onor integral with the bed plate I'. The position of the shuttle is unique in that it is mounted justl beneath plate in suitable bearings one in the boss 39' andl another in a spaced boss 42 near the right hand end of the-bed. plate. This shaft is mounted in bushings 43 of the self-aligning type, as described in connection with the main shaft. On the outboard side of the boss 42 shaft 46 supports a sprocket 44 identical in size to sprocket 45 on the main shaft and the two are connected by a silent chain 46 of' conventional form which extends through a slot 41 in the bed plate and is housed within the standard. The rear reach of the chain is i-n tension, under the direction of operation illustrated, and the front reach is maintained tight to eliminate back lash and to compensate for wear by means of a tightener mechanism 50, seen in Figs. l and 4. It comprises an arcuate metal backing plate 5l shod with non-metallic material 52 for bearing on the surface of the chain. The whole is pivoted from a stud 53 secured in a boss 54 on the standardv wall. The plate 52 carries a helical spring 55 secured thereto by rivet 56 and bearing against the wall of the standard so as to impart a slight pressure against the slack reach of the chain to maintain it in uniform tension at all times.

The shuttle shaft runs at the same uniform speed as the main shaft but the under stitchforming mechanism is of the type requiring two full revolutions for each stroke of the needle, so that the vertical shaft 31 is driven from shuttle shaft 40 by means of helical gears 58 and 59, the former being on the vertical shaft and the latter on the horizontal. These gears are so constructed that two revolutions are imparted to the vertical shaft for each one of the horizontal.

In order to feed the fabric beneath the presser foot and to advance it the desirable amount between stitches, the machine is equipped with a feed device or point 60 adapted to be motivated by a suitable carrier 6l comprising a fore and aft member imparting horizontal and vertical components of movement in a manner to be described. The feed point is attached to the carrier by means of its integral depending arm 62 mounted in a vertical slot 63 in the carrier and vertically adjustable therein by means of screw 64 and lock washer 65, there being an elongated slot in the arm to accommodate the shank of the screw.

The feed carrier 6I includes an inclined rear portion 66, a central horizontal section 61 to which the feed point is attached, a vertical section 68, and forked portion 69 including the parallel arms 16 which straddle and act as the folower for eccentric 1l attached by means of its collar 12 to the outer end of the shuttle shaft 4I).

The rearv end of the feed point carrier is integral with a transverse section 14 best shown in Fig. 8, whose ends are provided with cone recesses to receive thel conical ended adjusting and mounting screws 1.5 carried in spaced arms 1'6; integral with or suitably attached to feed shaft 11, which is oscillated by mechanism subsequently to be described. This shaft 11 is appropriately journalled between spaced bosses on the bed plate. Thel arms 16 move to each side of the vertical position as the result of, this oscillation and in accordance with'the amount thereof determine the horizontal component of movement imparted to the carrier andi thus regulate theY length of the stitch.

The vertical movement which positions the feed point in and" out of contact with the under face of the fabric is achieved. by means of the eccentric on the shuttle shaft. This eccentric is novel in that it is tapered or conical in form and' the cooperating faces of the fork arms 10 are inclinedV and give them good contact therewith. This construction achieves two purposes. It eliminates the needv for accurate spacing between the arms of the eccentric follower as. is required with parallel sided eccentrics in order that both arms. closely engage the eccentric at all times, for by the simple expedient of adjusting the eccentric longitudinally on its shaft, by means of the set screw in its collar, the desired closeness of t between the eccentric and the working faces of the follower arms can be achieved. This is permitted because no lateral movement, i. e., lengthwise of the shuttle shaft, can take place at the fork because of the manner of mounting the opposite end of the carrier between the tapered screws.

In the usual sewing machine fork construction with the parallel fork faces any appreciable wear requires renewal of the fork, the eccentric or both, but with the present construction wear is compensated for by longitudinal adjustment of the eccentric on its shaft.

Rocking motion, within the range desired, is imparted to the feed shaft 11 from the main shaft I8 by means of the mechanism illustrated in Figs. 4 and 5. A heart shaped cam 80 is longitudinally adiustably secured to the main shaft by means of a suitable set screw and cooperates with the yoke end of a connecting rod 82 whose lower end is pivoted at 83 to arm 84 extending substantially horizontally from the right hand end of the feed shaft. This connecting rod 82 is a simple sheet metal punching and it has a vertically elongated hole 85 punched in its enlarged yoke end 36. The length of the hole is such that its ends entirely clear the cam but the sides thereof are turned in to form converging wings best seen in Fig. 6 at 81 forming the engaging means for the cam. The working surfaces of these wings face each other and areV axially disposed in respect to the connecting rod. The cam is tapered, as shown, for the same reasons as discussed in connection with the eccentric for operating the feed point carrier. As shown in Fig. 6 the cam itself has its transverse face inclined but straight, whereas the wings 8l have their working faces slightly cylindrical, thereby automatically solving the alignment problem and eliminating the need for costly adjusting means or extremely careful initial t and alignment.

The cam is inserted into the opening in the yoke which surrounds the cam entirely. Therefore, the connection yoke can be made very light in weight. A light-weight connection is necessary to reduce vibration. Open-end feed cam connections such as are used in the conventional machines are heavy in cross section and cause undesirable vibration and noisy running sewing machines.

Two flat faces in the yoke of the connection are in contact with the working surface of the cam; as the cam is rotated on the main shaft, the yoke in the connection follows the cam in Orbit.

In Fig. 7 there is shown a modified construction in which the cam 99 has its surface curved transversely while the wings 8l have flat faces. This achieves the same automatic alignment and also permits of adjustment for fit and compensation for wear by lateral movement of the cam.

The arm 84 on the feed shaft 1l is substantially horizontal and is adapted to be oscillated in both directions from this portion. It will be seen, however, that if the motion of the follower for cam 99 is unimpeded except at pivot 83 it will merely oscillate in a substantially fore and aft path about this pivot and will not impart motion to the feed shaft because of the almost vertical position of the cam follower faces. To permit of adjusting the amount of movement imparted to feed shaft and hence to the feed point, a supporting link 90 is pivoted to the head 8B by pivot pin 9| near its lower left hand corner as seen in Fig. 4. This short link carries a fulcrum pin 92 at its lower end, which is adjustable in position toward and from the connecting rod to change the inclination of the link. It will be seen that when a line through the fulcrum 92 and the pivot 9| is substantially parallel to the axis of the connecting rod 82, as seen in Fig. 5, that this rod merely oscillates laterally and has no vertical movement, but as the inclination of this line with the axis of the connecting yrod increases, that more and more of the motion of the cam will be imparted longitudinally to the connecting rod.

Manual stitch adjusting means is provided for changing the position of this fulcrum 92, which is constrained to move within a limited arcuate range by being carried by a second or suspension link 94 preferably of the same length as link 99, journalled on fulcrum 92 and having its opposite end journalled at 95 on a pivot shaft extending through the side of the standard and adjustable for applying friction to the end of the link by means of a screw and lock washer Sii. The position of the shaft 95 is such that in the intermediate position of the pin 9i their axes coincide.

The position of the fulcrum pin 92 in itsarc about pin 95 is manually adjustable by means of a bell crank lever 91 mounted on a pin 9S having an adjustment to provide frictional resistance to insure the lever remaining where positioned. This lever has a forwardly directed handle 99 extending through a slot on the front face of the standard and cooperating with a graduated arcuate surface |09 and has a second arm mi slotted at its upper end at 192 for a relatively close working fit on an extension of the fulcrum 92. By lifting the hand lever 99 the stroke of the connecting rod in its effective vertical direction is adjustable from zero to a maximum, and likewise the stroke of the feed point in its horizontal direction is commensurate to change the stitch length.

In Fig. 4 the position of the parts just described is such that a maximum stroke in the vertical direction is imparted to the connecting rod 82, for it will be seen that a line connecting the pivot 9! through fulcrum 92 would have an angle of about 30 with the axis of the connecting rod 82. In Fig. 5 the hand lever 99 is adjusted to a position where a line passing through the pivot 9i and the fulcrum 92 is parallel to the axis of the connecting rod 92 and in this position substantially no vertical movement is imparted to the latter and the stitch size is the minimum.

The parts of the stitch adjusting mechanism may be made from any suitable material, such for example, simple sheet metal stampings or such material as would require little or no machining, all of which maintains the cost at a minimum.

I claim:

1. In a sewing machine having a bed plate, a rotary main shaft, a feed shaft pivoted beneath the bed plate, means to oscillate said feed shaft comprising a cam driven by the main shaft, a connecting rod pivoted to an arm on said feed shaft and having a follower head cooperating with said cam, parallel follower surfaces parallel to the axis of said connecting rod and a link for guiding the movement of said rod pivoted to said head and having an elongated fulcrum pin at its opposite end, the improvement comprising a second link articulated to said fulcrum, a fixed pivot for the opposite end of said second link, and a frictionally held manual means slidably engageable with said elongated pin to adjust the position of said fulcrum to adjust the stitch length.

2. In a sewing machine, in combination, a rotatable main shaft, a paralleling rock shaft mounted for oscillation and having a radial arm, a connecting rod pivoted to said arm, a cam on the main shaft, said connecting rod comprising a sheet metal stamping having an enlarged head, an aperture in said head with walls completely surrounding said cam, two of said walls being parallel to the axis of the rod, said two walls being formed of flanges turned in from the opening to present cam follower surfaces adapted to both engage the cam simultaneously.

3. In a feed mechanism for sewing machines comprising a bed plate, a pair of spaced parallel shafts journalled beneath said bed plate, an eccentric on one of said shafts, means to continuously rotate the eccentric shaft, an arm on the other shaft, means to oscillate said second shaft so that the arm moves to opposite sides of a vertical position, a feed point carrier having means at one end pivoted to said arm, a fork on the opposite end of the carrier with its arms engaging said eccentric and a feed point secured to said carrier and operating through a slot in said bed plate, the improvement consisting of the working surface of said eccentric being graduated in diameter throughout its length, the eccentric-engaging surfaces of said arms being inclined to provide smooth engagement therewith, atleast-one of the cooperating-surfaces on the -eccentric andarms being" curved transversely to eliminate the-need for accurate initial alignment, said eccentric `being longitudinally adjustable on its shaft to provide accurate fit between the eccentric and both arms and said pivot means being constructed and arranged to preclude lateral or swinging movement of the feed point carrier to maintain the accuracy of said fit.

BERNARD A. SCHMITT.

Name Date VLeilich Apr. 30, 1889 Number Number Number Name Date, Richards Apr. 16, 1907 Gray Jan. 9, 191,2 Diehl et al. NOV. 24, 1914 Plumley ;Jan. 16, V1917 Ringe Nov. 21, 1922 Weller Apr. 6, 1926 Bingman Nov. 5, 1929 Kinzie YDec.28, 1937 Hohmann Jan. 24, 1939 Kaier Feb. 11, 1941 Pinkvoss Dec. 15, 1942 Myers July 13, 1943 FOREIGN PATENTS Country Date Great Britain of 1913 Great Britain Jan. 9, 1930

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