US3033141A - Adjustable drive for feed dog of a sewing machine - Google Patents

Description

H F. DANIEL May 8, 1962 ADJUSTABLE DRIVE FOR FEED DOG OF A SEWING MACHINE 5 Sheets-Sheet 1 Filed Jan. 30, 1959 y 1962 H'. F. DANIEL 3,033,141

ADJUSTABLE DRIVE FOR FEED DOG OF A SEWING MACHINE Filed Jan. 30, 1959 5 Sheets-Sheet 2 Fig.2

y 1962 H. F. DANIEL 3,033,141

ADJUSTABLE DRIVE FOR FEED DOG OF A SEWING MACHINE Filed Jan. 50, 1959 5 Sheets-Sheet 3 H. F. DANIEL May 8, 1962 ADJUSTABLE DRIVE FOR FEED DOG OF A SEWING MACHINE Filed Jan. 50, 1959 5 Sheets-Sheet .4

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ADJUSTABLE DRIVE FOR FEED DOG OF A SEWING MACHINE Filed Jan. 50, 1959 5 Sheets-Sheet 5 United. states Patent 3,033,141 Patented May 8, 1962 3,033,141 ADJUSTABLE DRIVE FOR FEED DOG OF A SEWING MACHINE Hermann F. Daniel, Stuttgart, Germany, assignor to Union Special Maschinenfabrik, G.m.b.I-I., Stuttgart, Germany Filed Jan. 30, 1959, Ser. No. 790,206 Claims priority, application Germany Feb. 12, 1958 4 Claims. {CL 112-410) This invention relates to an adjustable drive for the feed dog of a sewing machine which enables feeding of the material in opposite directions, i.e. forwardly and rear wardly, selectively under the control of the operator and to a predetermined variable extent.

Adjustable drives for the feed dogs of sewing machines are well known both in connection with lockstitch and chainstitch sewing machines. The ability to change the direction of feed at will has also been provided in connection with lockstitch machines. Such adjustable drives, including the reverse feed feature, have heretofore been extremely complicated and required a large number of parts. The operating connections for reciprocating the feed dog in constructions of this character have been taken from the drive shaft of the machine at a point quite remote from the feed dog rather than in the region of the latter. This has led to quite complicated constructions and has also made it very difiicult to control the stitch length, particularly in machines operating at high speeds. The excessive lengths of the parts and the number of parts involved has introduced play and twisting or other distortion tendencies which interfere with accurate control of stitch length.

A primary object of the present invention has been to provide an adjustable drive for a feed dog which makes possible a feed action in opposite directions and accurate control over the extent of feed. Toward these ends the new adjustable drive has been made with a minimum of parts and of compact construction, with the operating connections from the main drive shaft of the sewing machine relatively close to the region in which the feed dog operates. The new construction thus reduces to a minimum the play and distortion factors which interfere with the accurate control of the feed movement, particularly in machines operating at high speeds.

In the construction .of the present invention the feed bar which carries the feed dog is connected by a link or pitman with an eccentric on the main drive shaft in the base of the machine to provide upward and downward movements of the feed dog. The feed bar is also connected by a link or connecting rod with a feed rocker which is driven by the main drive shaft in the base of the machine to a constant angular extent. In the preferred construction, both of the links mentioned are connected with a downwardly and forwardly extending arm of the feed bar. Rock movements are imparted to the feed rocker by a pitman cooperating with an eccentric on the main drive shaft in the region of the feed bar. This rocker is provided with an elongated slot, preferably of arcuate form, which extends upwardly and downwardly from the neutral line connecting the axis of the feed rock with the point of connection of the connecting rod with the feed bar. The second-mentioned link or connecting rod has a slide element, preferably having a roller, arranged to be shifted upwardly and downwardly within the slot mentioned. Depending upon the position of this element within the slot in relation to the dead center thereof, as determined by the neutral line mentioned, the feed dog will 5 be given a movement either forwardly or rearwardly at the time the feed dog is lifted into engagement with the work. In the preferred embodiment of the invention the feed bar is pivotally mounted at one end upon a second rocker arranged to rock about the same axis as the feed rocker described. It is, however, free to swing about that axis independently of the feed rocker and to the extent and in the direction determined by the particular location at any instant of the above-mentioned element within the slot of the feed rocker.

Another feature of the invention is the arrangement by which the slide element cooperating with the arcuate slot in the feed rocker is shifted to desired positions along said slot. This arrangement is such that a spring normally urges the slide element into the position which will bring about a forward feed action by the feed dog to the extent determined by the particular setting of the mechanism. Manually adjustable means is provided for determining this extent of feed. Other means operable at the will of the operator, either by hand, foot or knee action, are provided for shifting the slide against the action of the spring to bring about a reverse feed action of the feed dog to the same predetermined extent. The mechanism provided for accomplishing these results comprises a rock shaft having secured thereto, at one end, an arm which is connected with the slide element for shifting the same. A spring normally urges the rock shaft in one direction until it is arrested by certain adjustable stop means. This stop means comprises a disc fixedly mounted on the frame of the machine at the front of the base or vertical standard and a turnable disc mounted on a rock shaft extending through the front wall of the frame to a point adjacent the firstmentioned rock shaft. The turnable disc is secured to the second rock shaft outwardly of the fixed disc, with its inner face adjacent the outer face of the fixed disc, and carries a longitudinally adjustable screw, the inner end of which is arranged to cooperate with obliquely disposed surfaces of a V-shaped recess in the fixed disc. This arrangement is such that the extent to which the turnable disc and its shaft may be rotated is determined by the depth of penetration of the screw into the recess, i.e. by

the location of the inner end of the screw in relation to the apex of the converging, oblique surfaces of the recess. The opposite end of the shaft which carries the turnable disc is connected by suitable linkage with the first-mentioned rock shaft so that the two turn in unison. The adjusting mechanism may be operated to bring about a reverse feed action of the feed dog either by manual operation of a lever connected with the turnable disc or by connections from a treadle or a knee press member to an intermediate point of the first-mentioned rock shaft. The extent of rotation of the latter by any of the means mentioned is limited by the engagement of the inner end of the adjustable screw with the oblique wall of the recess in the fixed. disc opposite to that which is engaged under the action of the spring. The arrangement is such that the slide element is shifted below the axis of the feed rocker to an extent which will provide a reverse feed stroke of the length determined by the setting of the adjustable screw.

Still another feature of the adjusting mechanism is that it includes a fixed locking pin on the turnable disc which engages a shoulder on the fixed disc when the adjusting screw mentioned above is withdrawn completely. At this time the fixed locking pin limits the extent of rotation of the two rock shafts mentioned, under the action of the spring, to set the feed bar drive for a maximum stitch length in the forward direction of movement of the fabric. It will also cooperate with another shoulder on the stationary disc to limit the turning movement of the two rock shafts in the opposite direction in response to manual, knee or foot operation. This will determine the maximum feed stroke or stitch length in the rearward direction of movement of the fabric.

The adjustable drive mechanism for the feed bar provided in accordance with the present invention is of very simple construction and more reliable in its operation than devices heretofore provided for the same general purposes. The driving connections from the main shaft in the base to the feed bar are all located within a relatively small space in the region of the feed bar and relatively few and simple parts are required for the purpose.

In accordance with the invention simple means are provided for indicating to the operator the stitch length for which the drive mechanism is set. This comprises a pointer carried by the rotatable disc of the adjusting mechanism which moves across a scale carried by the fixed disc mentioned. The normal position of the pointer indicating the extent of forward feed for which the machine is set is determined by the cooperation of the end of the adjusting screw with the oblique surface of the recess in the fixed disc against which it is urged by the spring. In lieu of this arrangement, a scale may be provided on the front face of the vertical standard and arranged to cooperate with a pointer or the like provided on a lever connected with the rotatable disc and forming the manual means for turning the latter.

Both the driving connections from the main shaft to the feed bar and the connections from the turnable disc of the adjusting mechanism to the slide element which cooperates with the arcuate slot to determine the extent and direction of feed are of completely positive action. There is no danger of slippage between any of the parts in either of these mechanisms.

Other objects, features and advantages of the invention will appear from the detailed description of a preferred embodiment of the same which will now be given in conjunction with the accompanying drawings, in which:

FIG. 1 is a front elevational view of a lockstitch sewing machine embodying the invention;

FIG. 2 is a bottom view of the machine with a cover plate removed from the bottom of the vertical standard;

FIG. 3 is a view partially in end elevation and partially in vertical section in the region of the stitch length adjusting mechanism;

FIG. 4 is a transverse vertical section through the base of the machine in the region of the feed bar and related mechanism;

FIG. 5 is a horizontal sectional view through the portion of the base of the machine in the region of the work feeding mechanism;

FIG. 6 is a side view of the feed dog and the feed bar and shows schematically the various elements through which the feed bar is operated from the main drive shaft in the base;

FIG. 7 is a side view of the feed stroke adjusting mechanism as seen from the right in FIG. 1

FIG. 8 is a face view of the feed stroke adjusting mechanism as seen from the left in FIG. 7;

FIG. 9 is an outer face view of the fixed disc of the feed stroke adjusting mechanism; and

FIG. 10 is a view of the parts shown in FIG. 8

as seen from a point below the latter and looking upwardly at an angle of 45 toward the left.

The illustrative machine embodying the invention has the conventional frame structure of a modern lockstitch sewing machine and may be of the general character disclosed in the patent to Reimer, No. 2,643,625, granted June 30, 1953. It embodies a base or bed 1 and an overhanging arm 2 which are connected by the usual vertical standard. Extending longitudinally of the arm 2 is a drive shaft to the right end of which, outside of the frame, there is secured a pulley 3 and handwheel 4 by which the shaft may be rotated. It will be understood that the pulley 3 is connected in the conventional manner with a suitable power source. At its opposite end the drive shaft in the arm 2 is connected through the usual crank and link with a needle bar 5 for reciprocating the latter. In the base or bed of the machine there is provided a main drive shaft 6 which is operatively connected, through gearing or the like in the vertical standard, with the drive shaft which carries the pulley 3. Suitable connections are provided from the drive shaft 6 for the operation of the work feeding mechanism and a complementary stitch forming device, such as a rotary hook, which cooperates with the needle in the formation of stitches.

The work feeding mechanism comprises a feed bar 7 which is given a four-motion movement by means of eccentrics 8 and 9 on the shaft 6 (FIGS. 2 and 5). The feed bar 7 has its rearward end pivotally connected with a rocker 10 (FIG. 4) which is arranged to swing freely about a stationary shaft 10. Eccentric 8 cooperates with a strap at the upper end of a link or pitman 11, the lower end of which is pivotally connected to an arm 12 which extends downwardly and forwardly from the feed bar 7. The arrangement is such that the bar has its forward end lifted and lowered during each revolution of the shaft 6, as is schematically indicated in FIG. 6. Becentric 9 receives a strap at the forward end of a link or pitman 13, the rearward end of which is pivotally connected with a feed rocker 14 mounted on the stationary shaft 10. The feed rocker 14 is thus given a swinging movement of fixed magnitude about the stationary shaft 10. A forwardly extending portion 15 of the feed rocker 14 is provided with an arcuate slot which extends substantially equal distances above and below the axis of the shaft 10. In this arcuate slot there is arranged to slide a roller or block carried at the rearward end of a link or connecting rod 16. This slide element is shown at 17 in FIG. 6. At its forward end the link or rod 16 is pivotally connected with the downwardly extending arm 12 of the feed bar 7. It will thus be seen that as the feed rocker 14 is swung by the connections described from eccentric 9, the feed bar 7 will be reciprocated longitudinally by means of the link or rod 16. The extent of reciprocation will be determined by the position of the slide element 17 within the arcuate slot of portion 15 of the feed rocker. No movement will be imparted to the feed bar 7 when the slide element 17 is so positioned as to align the link 16 with the axis of the shaft 10. The greater the upward or downward movement of the slide 17 from this dead center or neutral position, the greater will be the movement of the feed bar 7. Also, it will be noted that when the slide 17 is above the neutral position mentioned, the link 16 will cause the feed bar 7 to beshifted toward the right (FIG. 6) as the feed rocker 14 is moved in a colckwise direction and the feed bar 7 will be shifted toward the left as the feed rocker is swung in a counterclockwise direction. On the other hand, when the slide element 17 is shifted downwardly below the neutral position, the reverse movements will be imparted to the feed bar 7. Thus, the latter will be shifted toward the left upon the clockwise movement of the feed rocker 14 and will be shifted toward the right upon the counterclockwise movement of the feed rocker. Since the feed rocker 14 is given its swinging movements in a predetermined time relation to the lifting and lowering movements of the forward end of the feed bar by the eccentric 8, it will be seen that the feed dog 18 carried by the feed bar will be active in one direction of movement when the slide element 17 is above its neutral position and in the opposite direction when the slide element 17 is below the neutral position.

The above-described movements of the various parts are indicated schematically in FIG. 6. The arrows indicate the direction of movement of the various parts and where they point in both directions it is intended to indicate that the part moves in both directions. The double-headed arrows on some parts, such as the slide 17 and the link 16, indicate the variable extent of movement of these in both directions. Just above the feed dog 18 the elliptical formation shows that the effective part of the movement of the feed dog, represented by the top portion of the ellipse, may be in either direction, depending upon whether the slide 17 is above or below its neutral position adjacent the axis of the fixed shaft 10. When the slide is above this neutral point the feed dog will be effective in advancing the work toward the left (FIG. 6) and when the slide is below the neutral point the feed dog will advance the work in the direction toward the right in FIG. 6.

The slide 17 is connected by means of a link 19 (FIG. 4) to the outer end of a curved or bent lever 21 secured to a rock shaft 22. Shaft 22 extends parallel with the drive shaft 6 and at its end adjacent the vertical standard of the frame is connected by arms 23 and 24 (FIGS. 2 and 3) with a setting device adapted to adjust the feed stroke and hence the stitch length to be provided. This setting device comprises two discs 25 and 26. Disc 26 is fixedly secured to the outer face of the front wall of the frame while disc 25 is turnable in relation to disc 26 and carries an operating lever 27 (FIGS. 1 and 3) which may be used to manually turn the disc. A screw 28 has screw threaded engagement with the disc 25 and has a rounded inner end 31 arranged to cooperate with the oblique walls of a V-shaped recess 29 in the disc 26. By turning the screw 28 its rounded, inner end may be adjusted to a greater or lesser depth within the recess 29. The further the rounded end extends into the recess the shorter will be the stitch length provided. A knurled locknut carried by the screw 28 serves to retain it in any adjusted position. Disc 25 is secured to the outer end of a shaft 34 extending through the front wall of the frame of the machine and downwardly at a suitable angle. At its inner end the shaft 34 has secured thereto the arm 23 which is connected by a link with the arm 24 secured to the rock shaft 22. A torsion spring 32 (FIG. 2) mounted on the shaft 22 has one end engaged with a collar secured to the shaft and its other end engaged with a portion of the frame. It is arranged to urge the shaft 22 in a clockwise direction (FIG. 4) and through the arms 23 and 24 turns the shaft 34 and disc 25 until the rounded end 31 of screw 28 engages one of the walls of the recess 29, as shown in FIGS. 3 and 7. By virtue of this arrangement the position of the slide 17 in the upper portion of the arcuate slot of part 15, under the influence of spring 32, will be determined by the position to which the inner end of the screw 28 has been adjusted. Also the extent to which the slide 17 may be moved downwardly below the dead center or neutral point by rotation of the shaft 22 through the turning of disc 25 by lever 27, for example, will be limited by the engagement of the rounded end 31 of screw 28 with the opposite sloping wall or surface of the recess 29. As previously explained, the extent of longitudinal movement of the feed bar 7 and feed dog 18 will be determined by the position of the slide 17 in the arcuate slot and will thus be controlled by the adjustment of the screw 28. When the slide is in the upper portion of the slot the work will be fed forwardly, i.e. from front to rear of the work support, while when the slide is below the neutral point the work will be fed in the opposite direction.

In order to prevent excessive turning of the disc 25 and the connected parts when the screw 28 is moved outwardly to carry its rounded end out of cooperation 'with the recess 29 a stationary lock pin 33 (FIG. 7) is provided on the disc 25 to cooperate with a shoulder on'the disc 26. This establishes the maximum feed stroke or stitch length for which the machine may be set. Excessive turning of the disc 25, if the lock pin 33 were not provided, might produce jamming of the device under the force of the spring 32.

A pointer 37 carried by the disc 25 and cooperating with a scale on an extension 36 of disc 26 serves to indicate the stitch length or feed stroke for which the machine has been set by means of the screw 28. The zero position on the scale corresponds with the turning of the screw 28 until its rounded end 31 engages the bottom or apex of the recess 29. As the screw is turned to withdraw its point outwardly from the recess, and the spring 32 turns the disc 25, the pointer 37 will move to successively higher numbers on the scale representing increasingly greater stitch lengths.

As shown in FIG. 2, there is secured to the shaft 22 an arm 35 having a split collar which may be clamped to the shaft in any adjusted position by means of the screw shown. Arm 35 is adapted for connection, by means of a chain or rod, with a foot operated treadle or a knee press member in a manner well known. Upon operation of the treadle or knee press the shaft 22 will be rocked to shift the slide element 17 along the arcuate slot against the action of the spring 32 in the same man- 'ner as when the operating lever 27 is moved. When the shaft 22 is thus turned, it will serve to turn the shaft 34 through the connections 23, 24 and will thus cause the disc 25 to turn until the point 31 of screw 28 is brought into engagement with the opposite oblique wall of the recess 29. Thus the extent of turning of the shaft 22 will be determined by the adjustment of the screw 28.

While an illustrative embodiment of the invention has been described in considerable detail, it will be understood that various changes may be made in the construction and arrangement of parts within the scope of the appended claims.

What is claimed is:

1. In a sewing machine having a base and an arm extending over said base, a reversible work feeding mechanism in said base comprising a horizontally disposed feed bar arranged for pivotal movement about a horizontal axis and for longitudinal reciprocatory movement along the line of feed, a rotary drive shaft in said base, a rock member in said base arranged for rocking movement about a second horizontal axis, said two horizontal axes being parallel with the axis of said shaft and on the same side thereof, connections from said shaft for imparting rocking movements of fixed predetermined extent to said rock member, said member having an arcuate slot extending above and below said second horizontal axis, a slide shiftable along said arcuate slot, a link having one end pivotally connected directly with said feed bar at a point thereon a substantial distance away from said first-mentioned horizontal axis and its other end pivotally connected with said slide, and means operable at the will of the operator for shifting said slide along said slot between positions above and below said second horizontal axis.

2. In a sewing machine of the character set forth in claim 1, a second rocker pivotally mounted for free rocking movement about said second horizontal axis, said feed bar being pivotally connected with said second rocker at a point removed from said second horizontal axis.

3. In a sewing machine of the character set forth in claim 1, spring means for normally urging said slide toward one end of said arcuate slot, said means operable at the will of the operator serving to move said slide against the action of said spring to a predetermined position along said slot.

4. In a sewing machine of the character set forth in claim 1, said feed bar having an arm extending downwardly and forwardly beneath said drive shaft, an eccentric on said shaft and connections therefrom to said arm of the feed bar for imparting lifting and lowering movements to the forward end of the feed bar, said link having its one end connected with said arm of said feed bar for imparting longitudinal movements to the latter.

References Cited in the file of this patent UNITED STATES PATENTS Seymour June 16, Grieb Oct. 16, Merrow Dec. 15, Nissen Mar. 17, Becker Oct. 15, Pagni June 21, Hayes Oct. 29, Ayres Dec. 31,

FOREIGN PATENTS Great Britain July 21,

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