US3437062A - Mechanism for automatically adjusting the height of a top feed foot - Google Patents

Description

I 8, 1969 H. w. HACKLANDER 1 3, 37,062

MECHANISM FOR AUTOMATICALLY ADJUSTING THE HEIGHT OF A TOP FEED FOOT Filed Oct. 11, 1966 Sheet of 2 v INVENTOR. Hans W. Hucklander BY Aprll 8, 1969 H. w. HACKLANDER 3,437,062

MECHANISM FOR AUTOMATICALLY ADJUSTING I THE HEIGHT OF A TOP FEED FOOT Filed Oct. 11, 1966 Sheet 2 or 2 INVENTOR.

Hans W. Hocklonder BY WITNESS: We, am fo ltoa zf AT ORNEY States Patent US. Cl. 112212 7 Claims ABSTRACT OF THE DISCLOSURE The following disclosure relates to a four-motion type upper feed mechanism wherein the range of vertical movement of the upper feeding foot is varied automatically in response to varying vertical movement of a presser-foot associated therewith.

The present invention relates to a four-motion type upper feed mechanism and in particular to apparatus for varying the range of the vertical movement of the feedingfoot for the upper feed mechanism in response to the passage of material of varying thickness beneath the feedingfoot and an associated presser-foot.

Where a feeding-foot for a four-motion type upper feed mechanism is utilized it is essential that the feeding-foot be capable of automatically accommodating to material of varying thickness. Such a change in the thickness of the material may be caused by, for example, a cross seam. Assuming that the range of vertical movement of the feeding-foot is fixed, an added thickness, beyond the range of vertical movement of the feeding-foot, in the material being fed beneath the feeding-foot will often cause the material to jam between the feeding-foot and the work surface.

It is an object of this invention, therefore, to provide improved means for automatically detecting a change in the thickness of material being fed beneath the feedingfoot and thereafter automatically adjusting the range of vertical movement of the feeding-foot to accommodate to the change in the thickness of the material.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a sectioned end elevational view of a sewing machine incorporating the apparatus of the present invention, and

FIG. 2 is a perspective view of selected elements of the sewing machine shown in FIG. 1.

Turning now to the drawings, there is shown a sewing machine frame including a bed 10 from which rises a standard 12 supporting a bracket arm 14, that terminates in a head 15, overhanging the bed. A main shaft 16 journaled lengthwise in the bracket arm drives all of the moving parts of the sewing machine and may be actuated by an electric motor, foot treadle or the like, none of which is shown in the drawings.

The main shaft 16 is adapted to drive conventional stitch forming instrumentalities including a loop taker, indicated generally at 18, and an endwise reciprocating needle mechanism, indicated generally at 20. The operation of such stitch forming instrumentalities is well known in the art and will not be described further.

The lower four-motion work feeding mechanism shown 3,437,062 Patented Apr. 8, 1969 in the drawings includes a feed-dog 22 secured to a feeddog bar 24 beneath the bed 10. Feed advance and return movements are imparted to the feed-dog bar 24 from an oscillating feed advance rock shaft 26 connected to the feed-dog bar 24 by means of a rock arm 28. The feed advance rock shaft 26 is oscillated by means of conventional connections 30 in the standard from a feed cam 32 on the main shaft 16. The connections 30 may include conventional regulating means 34 for varying the stitch length. Rising and falling motions are imparted to the feed-dog bar 24 from an oscillating feed lift rock shaft 36 in the bed. The feed lift rock shaft 36 is provided with a. rock arm 38 connected by means of a link 40 to the feeddog bar 24. It will be appreciated that as is conventional in the art the lower work feeding mechanism as described above and the upper Work feeding mechanism described below are timed relatively to the needle reciprocation so that the feed dogs advance the work material while the needle is raised out of the work material.

The upper four-motion feeding mechanism shown in the drawings includes a vertically arranged feed-bar 42 carrying a feeding-foot 44 off-set inwardly (towards the standard) of the feed-bar and adapted to move in a slot 46 formed in a presser-foot 48 connected to the lower end of a resser-bar 50 that is mounted for endwise movement in the head end of the bracket arm 14. Feed advance movements are imparted to the feed-bar 42 by an upper rock shaft 52 through a vertically arranged crank arm 54 secured on the head end of the shaft 52 and connected at its free end by a link 56 to an intermediate point on the feed-bar 42. Thus, oscillation of the upper rock shaft 52 will impart feed advance movements to the feed-bar 42. Oscillation is imparted to the upper rock shaft 52 by a link 58 secured at one end to the standard end of the shaft 52 and connected at its other end to the top of a pitman 60 arranged vertically in the standard 12. The bottom end of the pitman 60 is connected to one end of a link 62 in turn secured to the feed advance rock shaft 26. The feeding-foot 44 and the feed dog 22 are driven in unison by the same shaft 26, when it is rocked, thereby providing a uniform top and bottom feed advance for the work material.

The feed-bar 42 is provided with endwise reciprocat ing movements by the spring-drive combination now set forth. A crank arm 64 is connected at one end to the top of the feed-bar 42 and is secured at its other end to one end of a short pivot shaft 66 pivotally mounted in a lug 68 that extends outwardly from the bracket arm 14. A cam follower arm 70 is secured at one end to the other end of the short pivot shaft 66. The free end 71 of the cam follower arm 70 rides on an upper camming surface 72 of a cam arm 74 having an undersurface formed with a fiat segment 76 that is slidingly contacted by a feed lift eccentric 78 secured to the main shaft 16. As the main shaft 16 rotates the eccentric 78 lifts the cam follower arm 70 through the intermediacy of cam arm 74 thereby to pivot the shaft 66 and lift the crank arm 64 and the feed-bar 42 upwardly against the bias of a spring 80 secured at one end to the crank arm 64 and at the other end to a lug 81 on the bracket arm 14. Thus, the bias of the spring 80 functions to supply the falling movement of the feed-bar 42 while the eccentric 78 imparts the rising movements to the feed-bar through the intermediate elements described above.

The timing of the advance movements and the rising and falling movements of the feeding-foot 44 are such that the advance movements of the feeding-foot 44 in a feeding stroke is made with the feeding-foot 44 lowered in engagement with the work and the turn movement occurs when the feeding-foot 44 is out of engagement with the work. The movements of the feeding-foot 44 are synchronized with the action of the lower feeding mechanism including the feed-dog 22.

The means for automatically adjusting the range of vertical movement of the feed-bar 42 in response to changes in the thickness of material passing beneath the presser-foot 48 will now be described in detail. A cam crank unit includes a presser-bar follower arm 82 one end of which is secured to a bearing sleeve 84 in which the upper rock shaft 52 is journaled. The bearing sleeve 84 is pivotally mounted in a lug 86 extending outwardly from the bracket arm 14. The free end of the follower arm 82 contacts an upper fiat surface 88 of a block 90 secured to the presser-bar 50. A spring 87 extending between the arm 82 and a lug 89 on the bracket arm 14 serves to bias the arm 82 downwardly against the block 90. The other end of the bearing sleeve 84 is secured to one end of a crank arm 92, the other end of which is pivotally connected to the cam arm 74. The camming surface 72 includes, at the free end segment of the cam arm 74, an upwardly inclined segment 94 positioned between an upper horizontal segment 96 and a lower horizontal segment 98.

When material of relatively small thickness is fed beneath the presser-foot 48 the downwardly biased presserbar 50 moves the block 90 to a first vertical position. The block 90 in turn, pivots the follower arm 82 which moves the cam arm 74 to a first horizontal position through the intermediacy of the sleeve 84 and the crank arm 92. In this example illustrating the operation of the mechanism it will be arbitrarily assumed that the free end 71 of the cam follower arm 70 will ride on the lower horizontal segment 98 of the camming surface 72 with the cam arm 74 in the first position. In this first position of the presser-bar the eccentric 78 imparts a rising and falling movement to the feed-bar 42 through a first vertical range. Should a portion of the material being fed beneath the resser-foot suddenly increase in thickness due, for example, to cross scam, the presser-bar, since it is spring biased, will move upwardly to accommodate to the chnage in material thickness. This upward movement of the resser-bar lifts the block 90 to a second vertical position. The upward movement of the presserbar pushes the follower arm 82 upwardly and pivots the crank arm 92 which slides the cam arm 74 over the eccentric 78 in a direction away from the operator to a second horizontal position. As the cam arm 74 slides in a direction away from the operator to the second horizontal position the free end 71 of the cam follower arm 70 slides up the inclined surface 94 and pivots the shaft 66 which in turn pivots the crank arm 64 upwardly to raise the feed-bar and feeding-foot 44. In the second horizontal position the free end 71 of the cam arm 74 will ride on either the upwardly inclined segment 94 or the upper horizontal segment 96 of the camming surface 72 depending upon the extent of the increase in the thickness of the material. Thus, the feed-bar now rises and falls through a second and higher vertical range thereby automatically accommodating the feeding-foot to the increased thickness of the material passing beneath the presser-foot.

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

1. In a sewinm machine having a frame including a work support, an overhanging bracket arm and a bracket arm head, a presser-bar mounted for endwise movement in said bracket arm head, a presser-foot carried by the lower end of said presser-bar, a feed-bar mounted for vertical movement in said bracket arm head, means for imparting rising and falling movements to said feed-bar, means for imparting feed advance movements to said feed-bar, means for automatically adjusting the range of the rising and falling movements of said feed-bar in response to a variation in the height of the presser-foot relatively to the work support due to a variation in the thickness of work material passing beneath said presserfoot on said work support, said last named means including: a cam movable in response to vertical motion of said presser-bar, means for transmitting the vertical motion of said presser-bar to said cam, a cam follower movable in response to the movement of said cam and means for transmitting the movement of said follower to said feedbar to adjust the height of the feed-bar.

2. In a sewing machine having a frame including a work support, an overhanging bracket arm and a bracket arm head, a presser-bar mounted for endwise movement in said bracket arm head, a resser-foot carried by the lower end of said presser-bar, a feed bar mounted for vertical movement in said bracket arm head, means for imparting rising and falling movements to said feed-bar, means for imparting feed advance movements to said feed-bar, means for automatically adjusting the range of the rising and falling movements of said feed-bar in response to a variation in the height of the resser-foot relatively to the work support due to a variation in the thickness of work material passing beneath said presserfoot on said work support, said means for imparting rising and falling movements to said feed-bar including a main shaft journaled in said bracket arm and said means for automatically adjusting the range of said rising and falling movements of said feed-bar including a presserbar follower arm operatively connected to said presserbar and means for transmitting movement, imparted to said presser-bar follower arm by the endwise movement of said presser-bar, to said feed-bar, said transmitting means including a cam arm operatively connected to said presser-bar follower arm, said means for imparting rising and falling movements to said feed-bar including said cam arm, said cam arm being operatively connected to and driven by said main shaft, a cam follower arm operatively connected to said feed-bar, said cam arm having a non-linear surface, said cam follower arm formed with a finger adapted slidingly to contact said non-linear surface of said cam arm, whereby upon rotation of said main shaft rising and falling movements are imparted to said feed-bar and upon endwise movement of said resser-bar said cam arm is moved relatively to said cam follower arm thereby automatically adjusting the range of the ring and falling movements of said feedbar.

3. In a sewing machine having a frame including a work support, an overhanging bracket arm and a bracket arm head, a presser-bar mounted for endwise movement in said bracket arm head, a presser-foot carried by the lower end of said presser-bar, a feed-bar mounted for vertical movement in said bracket arm head, means for imparting rising and falling movements to said feed-bar, means for imparting feed advance movements to said feed-bar, means for automatically adjusting the range of the rising and falling movements of said feed-bar in response to a variation in the height of the resser-foot relatively to the work support due to a variation in the thickness of work material passing beneath said presserfoot on said work support, said means for automatically adjusting the range of said rising and falling movements of said feed-bar including a member secured to said presser-bar, resser-bar follower arm formed with a free end adapted to contact said member and means for transmitting movement, imparted to said presser-bar follower arm by said member upon endwise movement of said presser-bar, to said feed-bar, thereby adjusting the range of said feed-bar rising and falling movements.

4. A sewing machine as set forth in claim 3 wherein said means for imparting rising and falling movements to said feed-bar includes a rotary shaft journaled in said sewing machine and a cam arm, and said transmitting means includes said cam arm operatively connected to and driven by said rotary shaft, said cam arm being formed with a surface having a horizontal portion and an inclined portion, a cam follower arm operatively connected to said feed-bar and formed with a free end adapted slidingly to engage said surface of the cam arm, whereby upon rotation of said rotary shaft rising and falling movements are imparted to said feed-bar and upon endwise movement of said presser-bar said inclined portion of said cam arm is moved relatively to said free end of the cam follower arm thereby automatically adjusting the range of the rising and falling movements of said feed-bar.

5. A sewing machine as set forth in claim 3 wherein said means for imparting rising and falling movements to said feed-bar includes a main shaft journaled in said bracket arm and an eccentric driven by said main shaft and said transmitting means includes a cam arm operatively connected to said presser-bar follower arm, said cam arm being formed with a first and a second surface, said first surface being in operative engagement with said eccentric, a cam follower arm operatively connected to said feed-bar, said cam follower arm having one end adapted operatively to engage the second surface of said cam arm, whereby rotation of the main shaft drives Said eccentric thereby to impart rising and falling movements to said feed-bar through the intermediacy of said cam arm and cam follower arm.

6. A sewing machine as set forth in claim 5 wherein the second surface of said cam arm is formed with a. series of connected surfaces of different levels, whereby upon variation in the height of the presser-bar relatively to the work support the cam follower arm is moved relatively to the cam arm thereby moving said one end of said cam follower arm along the second surface of said cam arm and varying the height of the feed-bar relatively to the work support a distance corresponding to the variation in the height of the resser-bar.

7. In a sewing machine having a frame including a work support and a bracket arm overhanging said work support, a spring biased presser-bar mounted for endwise movement in said bracket arm, a presser-foot carried by the lower end of said presser-bar, a main shaft journaled in said bracket arm, means for rotating said main shaft, an upper rock shaft pivotally mounted in said bracket arm parallel with said main shaft, means for oscillating said rock shaft upon rotation of said main shaft, a feed-bar carrying a four-motion feeding foot mounted in said bracket arm, means for imparting feed and return movements to said feed-bar including a first crank arm secured at one end to said upper rock shaft and a link pivotally connected at one end to said first crank arm and at its other end to intermediate point on said feedbar, means for imparting rising and falling movements to said feed-bar in timed relation with its feed and return movements including an eccentric secured to said main shaft, a cam arm formed with a flat undersurface adapted slidingly to contact the surface of said eccentric, the top surface of said cam arm being formed with an inclined surface, a pivot shaft pivotally mounted on said bracket arm, a second crank arm secured at one end to said pivot shaft and connected at the other end to said feedbar, a cam follower arm secured at one end to said pivot shaft, the other free end of said cam follower arm being adapted slidingly to engage the top surface of said cam arm, means for adjusting the range of the rising and falling movements of said feed-bar in response to a variation in the height of the presser-bar relatively to the work support, said last named means including a member secured to said presser-bar a bearing sleeve pivotally mounted in said bracket arm, a spring biased follower arm secured at one end to said bearing sleeve and adapted to contact said member and pivotally respond to the variations in height of said presser-bar, a third crank arm secured at one end to said bearing sleeve and pivotally connected at the other end to one end of said cam arm whereby the pivotal movement of said spring biased follower arm pivots the bearing sleeve and third crank arm to move said cam arm relatively to said cam follower arm and slide the free end of the cam follower arm along the inclined top surface of said cam arm, thereby to pivot said second crank arm and vary the height of the feed bar relatively to said work support.

References Cited UNITED STATES PATENTS 2,415,383 2/1947 Becker 112-212 RICHARD J. SCANLAN, JR., Primary Examiner.

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