US2144802A - Sewing machine feed mechanism - Google Patents

Description

Jan. 24, 1939. R K HOHMANN 2,144,802

sEwiNG MACHINE FEED MECHANISM Original Filed Dad. 29, 1936 3 Sheets-Sheet l J Ill B; v K .NVENTOR ATTORNEY- Jan. 24, 1939. R. K HOHMANN I W SEWING MACHINE FEED MECHANISM Original Filed Dec. 29, 1956 3 Sheets-Sheet 2 ATTORNEY Jan. 24, 1939. R. HOHMANN 2,144,802

SEWING MACHINE FEED MECH'ANISM Original Filed Dec. 29, 1936 5 Sheets-Sheet 3 INVENTOR A'i'T'ORNEY Patented Jan. 24, 1939 "UNITED STATES PATENT OFFICE 2,144,802 SEWING MACHINE FEED MECHANISM Richard K. Hohmann, meme, N. Y. Original application December 29, 1938, Serial No.

Divided and this application April 3,

1937, Serial No. 134,729

7 Claims.

stitching operations in which no automatic work feed is needed or desired.

The said means comprise two cams, so mounted on a rotatable shaft of the sewing machine, such as the underbed hook driving shaft or upper needle bar shaft, that one of the cams may rotate with the shaft at all times, while the second cam may or may not rotate with the shaft accordingly as operation f the feed mechanism is or is not desired.

A further specific object of the invention is to include in the feed mechanism, novel and effective provisions for varying the stitch length,

not onlyin the normal stitching, but also in the backstitching, operation. My work feed mechanism improvements were primarily devised for use, and may be used with especial advantage, in portable domestic sewing machines, but may also be used with advantage in other sewing machines.

The various features ofnovelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages, and specific objects attained with its use,

had to the accompanying reference should 'be drawings and descriptive matter inwhich I have illustrated and described a preferred embodiment of the present invention.

or the drawings:

Fig. 1 is an elevation of the machine partly broken away and in section;

Fig.2 is an inverted plan view of the underbed mechanism of'the machine;

Fig. 3 is a rear end elevation of a lower portion of the sewing machine with a detachable drive mechanism cover plate removed;

Pg. 4 is a vertical section on the line H of Fig. 2;

Fig. 4A is a partial vertical section on the line lA-lA of Fig. 4;

Fig. 5 is a vertical section on the line 5-5 of Fig. 2;

Fig. 6 is a section taken similarly to Fig. 5,-but showing parts in different relative positions;

Fig. 7 is, apartial section on the line 1-1 of Fig. 2;

Fig. 8 is a section taken similarly'to Fig. 7, but showing Parts in difl'erent relative positions:

Fig. 91s a Fig. 8. a

As shown in the drawings, the sewing machine mechanism is partly received in, and is wholly supported by a base member A. The latter is in the form of a flat cast metal box having a removable top plate part B, forming the cloth or bedplatc of the machine. .-The hollow standard C, arm C, and head (3, andother frame parts C C, C", and C', as shown are all parts of a one partial section on the line 9-8 of piece metal frame casting, to which the bed plate B is secured as by screws. The parts C C C and C' are all within the round the lower portion of the standard C. The parts C and C are parallel, spaced apart foot or leg portions of the framework, which bear directly against the bottom wall of the base member A, and are detac bly connected thereto, by screws C".

The lower portion of the hollow standard C is enlarged at its rear to provide a housing for the upper portion of a driving element, shown as a grooved pulley D having an enlarged hub portion the bobbin winding operahand wheel for manual ad justments oi the mechanism. The said housing is closed at its rear sideby a removable are shaped cover part C', extending over the exposed hub portion D, and having horizontally extending foot portions detachably secured to the rear end wall of the base A. The pulley D is mounted on a crank shaft E, and driven by an electric motor F, shown as located wholly within the base A beneath the bed plate B and the armature shaft of which may carry a pulley driving .Pu'lley D through a belt F. To accommodate its bobbin winding use, the pulley D is preferably a socalled loo se" pulley, operatively secured to the crank shaft E only when clamped to the latter by an external clamping nut D threaded on the outer end portion E "bf the crank shaft E, and engaging the pulley D through a friction washer D splined on the shaft portion E.

The crank shaft E is journalled in frame bearings and extends across the interior of the ho].- low standard, C, with the cloth plate level. To facilitate its assembly and re-assembly, the rear or outer end portion E of the crank shaft is separable from the remainder or body portion of the crank shaft and normally connected to the latter by a key E The rotation of the crank shaft E gives rotative movements to the needle bar shaft 0, which passes horizontally through the hollow arm C, through a crank or-connecting rodor lever G. The latter has a lower hub portion G surrounding the crank pin portion E of the crank shaft E, and is provided at its upper end with a transverse pin G receivedin a radial slot a in a crank its axis preferably below base member A, and', covered by the plate 13, which is notched to surfurther referred to herein.

In the form of construction shown in Figs. 1, 2, and 3, the rotative movements of the crank shaft gives corresponding movements to the main underbed shaft H, through toothed gears E. and H carried by the crank shaft and underbed shaft respectively, which advantageously and as shown, are spiral gears, with a one to one gear ratio. The shaft H is journalled in aligned bearings in the frame C and 0, and in a bearing block C secured to the underside of the frame portion C.

has two arms I and I,*one generally parallel with, and the other transverse to, the shaft H,

which are adjustably clamped against the underside of the frame part 0* by clamping bolts I and I". The clamping bolt 1 for the arm I extending transversely to the shaft H passes through a hole in a bushing 1 which may be protated for adjustment purpose, in the hole in the arm I receiving it, and has its-hole receiving the clamping bolt 1 eccentric with respect to theperiphery of the bushing. In consequence, by loosening the clamping bolts, and angula'rly adjusting the bushing I, the hook shaft may be bodily adjusted toward the axis of the shaft H, as required to take up for wear of the gearsH" and I. The bolt 1'' passes through an opening in the-arm I elongated in the direction of the latter, so that when the clamping bolts are eased off, the hook shaft maybe bodily adjusted in the direction of the length of the shaft H to thereby properly position the hook relative to the path of movement of the .needle. To permit of easy lubrication of the'two bearings in the support I for the hook shaft, one above and the other below the gear I, the hookshaft is formed with an axial oil channel 1 closed at its lower end, but open to the bobbin chamber of the hook at its upper end, and formed with a lateral oil outlet 1 for each bearing. Those bearings may thus be readily lubricated, when the bobbin is removed from the hook, by dropping oil into the bobbin chamber.

In front of the gear H, the shaft H carries two work feed cams JA and JB. The cam JA is rigidly, though preferably adjustably, secured to the shaft H, but the cam JB, while normally in the fixed relation to the shaft H shown in Fig. '7, may be adjusted as and for the purpose hereinafter described, into the position shown in the Fig. 8 in which it does not share in the rotative movement of the shaft H. In the normal running position illustrated in Fig. '7, the rotation of the cams JA and JB give feed movements to a feed dog J through mechanism comprising a feed bar J, to which the feed dog J is rigidly secured. The feed bar J, which is gen-, erally horizontal, is formed at its rear end with upper and lower prongs J, which straddle a stationary guide pin C", forming a guide for the rear end of the feed bar in the longitudinal the upper front side inclined upwardly from movements of the latter, and forming a pivotfor the feed bar in its oscillatory up and down movements.' It is given its up and down oscillatory movements, in the normal stitching operation,. ,by the cam .113, against whichthe underside of the front by a spring .1.

end portion of the bar is normallyheld The feed bar .1 is given its longitudinal movements by a 'fork lever J, formed with upper and lower prongs J at its front end, which straddle the cam'JA. At its rear end, the fork lever is pivotally connected to the feed bar J by means of a pivot pin J carried by depending ear extensions J" from the lower prong J of the feed bar J'.

The oscillatory up and down movements given to the prongs J of the fork lever J by the cam JA normally give that lever, and thereby the feed dog J reciprocatory movements in the generally horizontal direction of the feed bar J, as a result of the interaction of a block J carried by a pivot pin J', projecting "laterally from the fork lever J with a guide member K, formed with a guide slot K receiving the block J". The member K is pivotally mounted on a horizontal stub shaft or post 0 parallel to the shaft H and anchored in the frame part C The part K has an arm connected by a pivot K to one end of a link K, having its other end pivotally connected by pivotpin K to an arm K carried by a rock shaft K. The latter is beneath the bedplate B, and parallel to the shaft H, and is joumalled in bearingscarried by the front frame part C at its underside. The rearend of the shaft K extends into the housing chamber for the pulley D, and has an operating arm K link connected to it, as shown in Figs. 1 and 3. The arm K projects through a slot C formed in portion of the housing wall, andelongated to permit of a substantial angular adjustment of the shaft K by manipulation of the outer end of the arm i The angular adjustment which may thus be given to the shaft K issufiicient to adjust \the angle of the inclination'me'mber K between positions respectively shown in Figs. 5 and 6. As shown in Fig. 5, the slot K in the member K is the horizontal and for wardly from the vertical plane through the axis of the shaft H. In the position shown in Fig. 6,

theslot K is inclined upwardly from the hori- .carried by the fork lever, then moves down in the slot K, and gives the feed dog J a rearward movement and thus effects the normal feed movement of the work away from the operator, who is in front of the machine, as the latter appears in-Flg. 1. With the member K adjusted into the position shown in Fig. 6, the feeding movement of the feed dog is toward the operator.

When the arm K is adjusted to make the direction of the slot K vertical, the feed dog will have no feeding movement. The extent of feeding movement, and consequently the length of each stitch formed, will progressively diminish to zero as the member K is progressively adjusted 75 from either of its positions shown in Figs.- 9 and 10, to the intermediate no feed position in which the slot K is vertical. The arm or finger K thus forms a readily accessible and easily operable actuating member of mechanism by which the direction of feed may be reversed, and by which the length of the stitch formed with either direction of feed may be varied as desired. As shown, the wall of the pulley housing in which the slot C is formed, is provided with scale marks C, which in conjunction with the index formed by the arm K", furnish an easily read indication of the direction of feed and length of stitch formed with any existing adjustment of the arm K".

The cam JB is adjustable longitudinally of the shaft H. To this endthe cam JB has a hub extension provided with circumferential collars JB' and JB spaced apart to provide a circumferential groove JB entered by a pin L carried by a lever L. The latter has one end pivoted at L to the supporting framework of the mechanism, and has its other end pivotally connected to one end of a link L which is beneath the clothplate, and has its other end pivotally connected to an operating lever L The latter is pivotally connected to the framework by a, pivoted pin L and extends up through a slot formed in the clothplate B adjacent the standard C. By oscillating the lever L, the cam member JB, under certain conditions, can thus be adjusted longitudinally of the shaft H, between its normal operative position shown in Fig. 7, and its inoperative position shownin Fig. 8.

In its operati"e position, the cam JB is connected to the shaft H to rotate with the latter, by means of a pinJB parallel to, and laterally displaced from the shaft H, and anchored in the cam JB and projecting from the face of the latter adjacent the cam JA. In the position of cam JB shown in Fig. 7, the pin JB extends into a socket formed for the purpose in the cam JA, which is rigidly secured to the shaft H. When the cam JB is displaced from the cam JA as shown in Fig. 8, the pin 313* is completely withdrawn from its socket in the cam-JA, and the cam JB is out of driving engagement with the shaft H.

Means are provided which, prevent the cam JB from being adjusted from the position shown in Fig. 7 into that shown in Fig. 8, except when the angular position of the cam JB is such that the feed bar J the cam JB, so that the feed dog J is then wholly below the top surface of the clothplate or bed of the machine. In consequence, with the cam JB in the position shown in Fig. 8, the rotation of the shaft H through cam JA gives movement to the feed dog J in the general horizontal direction of the feed bar J, but such feed dog movements will be idle, because the feed dog is below its work engaging level. The said means compelling the feed dog to be below the work engaging level, when the cam JB is in the position of Fig. 8, comprises a part M carried by the frame part 0 at the underside of the latter. The latter is at the right hand side of the cam JB when the latter is in the position shown in that Fig. 7. The collar JB is of sufiicient radial extent to engage the part M, and prevent movement of cam JB into the position shown in Fig. 8, except when the angular position of the cam JB is such as to bring afiattened edge portion J12, of the collar J13 into parallelism with the the cam JB into the manual adjustment by the operator.

bears against a low portion of underside of the member ures 8 and 9.

The purpose of holding the feed dog-J below its working level, effected by the adjustment of position shown in Fig. 8, is to facilitate. operations, such as darning operations. in which the work is preferably not subject to automatic feed action, but is free for When such an operation is being carried out, the usual pres- M, as shown by Fi sure foot N is ordinarily removed temporarily.

With the presser foot removed, as the needle starts up, and the needle thread is slackened, so

that in normal operation it forms a loop in .po-

sition for engagement 'by the thread engaging point of the hook I",

there would be occasional failure of the needle thread to form a loop in position for engagement by the hook, but for a special corrective device 0 (Fig. 4), which I provide. The device 0 is there is a tendency for the work to lift with the needle. In consequence,

a thread engaging finger or loop controller secured to' the frame opposite part C The device O, by engaging the portionof the needle thread adjacent, but above the eye in the needle OB, and at the side of the needle remote from the hook I, forces the thread to move through the eye of the needle as the latter starts its upstroke, and thus insures the formation of the proper thread loop at the hook side of the needle for engagement by the hook point, notwithstanding the tendency of the work to lift with the needle, when not prevented by the presser foot eiiect. The arrangement and operative action of the thread controller 0 need not be further illustrated and described herein, as it forms no part of the invention claimed herein, and is more fully disclosed in my prior application for patent, Serial Number 118,038, filed December 29, 1936, of which the present application is a divisicn. Said prior application contains claims 'on various novel features including the said controller O invented by me, and disclosed, but not claimed herein.

While novel features of my improved sewing machine may be used with advantage in sewing machines which are not primarily intended for domestic use, and which are not portable, it will be apparent to 'those skilled in the art that my improvements are especially well adapted for use,

and to contribute to the operative characteristics desirable, in small light weight portable sewing machines intended primarily for domestic use. In particular, it is to be here noted that the provisions made for rendering the feed mechanism inoperative during a stitching operation in which the normal feed connection is undesirable, and the provisions made for reversing the direction of the feed and for varying the length of the stitches formed, are desirable, not only because of their relative simplicity and effectiveness, but also because the entire feeding mechanism may be compactly and conveniently arranged in the available underbed space of the machine except for the operating members L and K", which project from the sewing machine structure at points conveniently located for engagement by the operator.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the apparatus disclosed, without departing from the spirit of my invention as set forth in the appended claims, and 7 that certain features of my invention may sometimes be used with advantage, without a correspending use of other features.

Havingnow described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a sewing machine comprising a workbed with a feed dog opening, the combination with a feed dog, of a rotatable cam and means through which the rotation of said cam gives said feed dog horizontal to and fro movements, a second rotatable cam and means by which the rotation of said second cam gives said feeddog movements upward to and downward from a position in which it extends through said opening, and means alternately operable to simultaneously rotate both cams or to rotate the first mentioned cam withoutrotating the second mentioned cam.

2. In-a sewing machine comprising a workbed with a feed dog opening, the combination with a feed dog, of a rotatable cam beneath said bed and means through which the rotation of said cam gives said feed dog horizontal to and fro movements, a second rotatable cam beneath said bed and means by which the rotation of said second cam gives said feed dog movements upward to and downward from a position in which it extends through said opening, and means alternately operable to simultaneously rotate both cams or to rotate the first mentioned cam without rotating the second mentioned cm.

3. In a sewing machine comprising a supporting structure including a workbed formed with a feed dog opening, the combination of a horizontal rotatable shaft beneath said bed, a cam mounted on said shaft, 2. feed dog, means through which said cam moves said'feed dog up into and down from a position in which it projects upwardly through said opening when said cam is rotated, means including an, operating part projecting from said structure for engagement by the hand of the operator for releasably connecting said shaft and cam for rotation of the latter by the shaft, and means for maintaining said cam, when disconnected from said shaft,-in position to hold the feed dog below its above mentioned position. 4. In a sewing machine comprising a workbed formed with a feed dog opening, the combination of a horizontalrotatable shaft beneath said bed, a cam secured to said shaft, a second cam mounted on said shaft and axially adjustable relative to the latter, means coupling said second cam to said shaft for rotation with the latter in one position of said cam axially of said shaft, means for holding said second cam, when in a second position axially of said shaft. against ro tation with said shaft and in a predetermined angular position, a feed dog, means through which the rotation of the first mentioned cam gives horizontal to and fro movements to said feed dog, and means-actuated by the rotation of said second cam to move said feed dog up to and down from a position in which it projects through said opening. and holding said feed dog out of its said position .when said second cam is in it said second axial position. 5. In a rotary hook sewing machine comprising a workbed, the combination with a rotating horizontal underbed hook driving shaft, of an underbed feed bar support, laterally displaced from said shaft, a feed bar movable up and down "and horizontally to and fro in a direction transverse to said shaft, a lever pivotally connected to said feed bar and cam means carried by said shaft giving said feed bar up and down movements and giving oscillatory movements tosaid lever, a member angularly adjustable about an axis beneath said bed and parallel to said shaft, and formed with a guideway extending transversely to said axis, said lever having a guide portion engaging the said guideway whereby'when said member is angularly adjusted to one side or the other of an intermediate position, the oscillatory movements given said lever by said second cam means gives said feed bar horizontal to and fro movements in timed relation with its up and down movements and of a magnitude which varies with the angular displacement of said member from said intermediate position, and the ing a workbed, the combination with a rotating horizontal underbed hook driving shaft, of an underbed feed bar support displaced from said shaft, a feed bar having one end in engagement with said support and movable relative thereto, angularly up and down, and horizontally to and fro in a direction transverse to said shaft, a cam carried by said shaft giving said bar its angular up and down movements, a second cam carried by said shaft, a lever pivotally connected to said feed bar and engaging, and given angular up and down movements by, said second cam, a member angularly adjustable about an axis beneath said bed and parallel to said shaft, and formed with a guideway extending transversely to said axis, said lever having a guide portion engaging the said guideway, whereby when said member is angularly adjusted to one side or the other of an intermediate. position, the up and down movements given said lever by said second cam gives said feed bar horizontal to and fro movements in timed relation with its up and down movements and of a magnitude which varies with the angular displacement of said member. from said intermediate position, and the phase relation of which to the up and down movements of the feed bar is varied approximately 180 by the angular adjustment of'said member from one side to the other of said intermediate position, and means including a manually operable part projecting from said structure for angularly adjusting said member about said axis.

I. In a sewing machine comprising a supporting structure including a workbed formed with a feed dog opening, the combination of a horizontal rotatable shaft beneath said bed, a cam mounted on said shaft, a feed dog, means through which said cam moves said feed dog up into and down from a pomtion in which it projects upwardly through said opening when said cam is rotated,

said shaft and cam for rotation of the latter by the shaft.

, RICHARD K. HOHMANN.

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