US3776159A

US3776159A - Material pressure foot for sewing machines

Info

Publication number: US3776159A
Application number: US00262188A
Authority: US
Inventors: E Angele
Original assignee: Pfaff Industriemaschinen GmbH
Current assignee: Pfaff Industriemaschinen GmbH
Priority date: 1971-06-21
Filing date: 1972-06-13
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04
Also published as: GB1390543A; DE2130719C3; JPS5617111B1; IT959307B; DE2130719A1; DE2130719B2

Abstract

A pivotally mounted apron or sole for applying pressure to a material being sewed is provided with locking means which temporarily locks the apron in substantially horizontal position until the initial edge of the material-to-be-sewed has passed beyond the needle in order to prevent partial or total blocking of the edge of the material by a slanted sole. Once the material to be sewn passes a predetermined point, the locking means is released so that the pivotable apron operates in its normal desirable way.

Description

[ 1 MATERIAL PRESSURE FOOT FOR SEWING MACHINES [75 Inventor: Eugen Angele, Kaiserslaute'rnllfalz,

Germany [73] Assignee: Pfaff Industriemaschinen GmbII,

Kaiserslautem/Pfalz, Germany 221 Filed: June 13, 1972 211 App]. N6; 262,188

[30] Foreign Application Priority'Data Mar. 10, 1972 Germany P 21 30 719.7

52 U. S.Cl. a ...112/235 51 1111. C1. D051) 29/02 58 Field 61 Search 112/235, 237,-23s, 112/236, 239, 1 50, 151, 240

[5 6] References Cited UNITED STATES PATENTS 2,147,128 2/1939 Sailer 112/235 Dec. 4, 1973 2,419,482 4/1947 Clayton 112/235 1 2,481,175 9/1949 Tamburro.... 112/235 3,511,198 5/1970 Hacking 112/235 FOREIGN PATENTS OR APPLICATIONS I 186,026 7/1960 Sweden .1 11 2/235 Primary Examiner-Jordan Franklin Assistant Examiner-Peter Nerbun Attorney-Greene & Durr 1 [57] ABSTRACT locking means is released so that the pivotable apron operates in its normal desirable way.

3 Claims, 2 Drawing Figures 1 MATERIAL PRESSURE FOOT- FOR SEWING MACHINES goods being sewed over its entire. bottom surface;

Where the center of rotation of the material pressure foot. apron remains generally behind the stitch forming place, the apron takes on-wh'em the material edge at the start of sewing: rests in front of the. center of rotation: a sloping position andthereby braces .itselfwedgeshaped against the edge of thematerial; The material transport at the start of the seam is then rendered difficult or fails completely with bulky-goods.Thentthematerial feed seizes the goods --with' only .a small portion of the teeth and high-pressuremust be applied against the slopingupright apron to overcomethe resistance of its spring pressure. Thereby, stitch accummulationor damage to the material by the forwarding. mechanism of the sewing machineresults. Withithis invention,

these drawbacks are avoided with: the aid o'fa single' means.

To that end, the invention is based on the technical problems of establishing the pressurefoot sole in an essentially horizontal position, while, atthe beginning of.

sewing, until there is an adequate transferofia sufficient amount of sewing goods under it.

According to the invention, this problem is solved by providing cooperating locking and unlocking means between the carrier and the pressure foot-sole, con.

structed and arranged so that the. locking meanslocksthe apron in an essentially horizontal position at the be: ginning of thesewing process'and the unlocking means automatically unlocks the lockduringthesewing process. Thereby the stitching can be started directly at the edge of the goods to be sewed, during which the bottom comprises a bar fastened thereon, a swivally mounted locking element on the carrier with a notched surface.

of a design for holding the bar and a springfor assuring the connection between the bar and thenotched surface. v

For assuring insertion of the lockingv element, the notched surface includes a leading surface for the-bar which limits the swivel range of the-bar.

In order that the pressure foot sole doesnot tip.with-- its head downward upon lifting. the material pressure foot, a pressure spring is arranged normally behind the coupling axis between the canier-andfltheusole; This pressure spring is also advantageously-used to guarantee the locking position of the bar.

In order to attain a completely automatic. in and outconnection of the locking mechanism-during. the sewing operation, a-spring presses the locking element towards the disconnected direction-"towardsa stop and. a casing-mounted stop projects in the motion path'of a sloping surface provided at the upper end of the .lock-.

ing element for the switching in of the locking means.

ln this'case, it is necessary that the position of the bar in: relation to the lower side of the sole be so chosen that the sole in thelocked positiontakes a slightly; rising sloping: position inthe directionof its top and moreover the unlocking stroke of the lock is determined in. such a way that it releases the locking bar in-the straight horizontalpositionof the sole. Theswitching in of the lock elements for the securing of the sole results automatically fromthe withdrawal of the material pressure foot at the end of a seam. v

The invention is especially advantageous when arranged in combination. with a material feed which by its lifting movement above the needle plate takes on a slight rising,sloping position. in. the direction; of the sup.- port, in which= the unlocking stroke of the lock connection: between. the bar and the notches surface is chosen smaller than the amount of the-sewing of the bar (about its horizontal-axis) from its horizontal position to its sloping position as produced by material feed. The apron can. then be locked. exactly in horizontal position whereby its optimal transport relation is provided; for starting the. sewing. The unlocking; of the lock results immediately after the edge of the sewing goods is pushed, forward to behind the center of rotation of the pressure foot sole, provided the shape regulated material feed swings the sole sofar that the bar is lifted from the notched surface of the locking element.

A practical example of the invention is shown in the drawing, and will. be more precisely described below.

In the drawing:

Fl G.-1 is a partial side view of a sewing machine with locked locking means of the. pressure foot apron or sole.

In the casing. 1 of the machine, the needle rod 3 equipped :with. the needle 2 is supported and is, in known way (not shown), driven through connecting rod 4. .Also, material pressure rod Sis slidably supported in bushing 6-in casing lQThe lower end of material. pressure-rod S- carries a material pressure foot 7, while on the:upper end, abovea sphere 8, there is impressed a leaf spring 9 attached in known way to the casing. Through a cup-like depression in the material pressure rod 5 and. in the leaf spring 9, the position of the sphere 8 is fixed.-

On the material pressure rod 5, a lifter 10 is attached, whose arm 11 is guided in a vertical slot 12 in the casing 1.

A shaft 13 is supported in the casing l, which on its inner end carries an eccentrically mounted lug l4 and Y to a portion of which, eittending outside the housing, is attached a hand lever "15. A pivot piece 16, in the line of sight (as shown) issupported in casing 1, behind slot l2f-and has its lower impact face 17 resting on lug 14 while its upper impact surface extends below arm 1 1. The material pressure foot 7 shows a carrier 19 which is screwed onto material pressure rod 5. On the lower part of the carrier 19 is the pressure foot sole or apron 20 pivotally supported by means of a linking pin 21, the. pivotability thereof being limited through stop faces 22.

and 23. Between the surfaces 23 and the sole 20, a

pressure spring 24 is arranged.

On the carrier 19 an arm 25 is developed, on which is pivotally supported a locking element 27 bymeans of a hinge pin 26. The locking element 27 shows a notch which is defined by a leading surface 28, a detent and a stop surface 29. The lead surface 28 and the stop surface 29 can determine the range of pivotability of the pressure foot sole 20, taking over from the stop surfaces 22 and 23, which is a technical advantage considering the large interval of the linking pin 21. The leading edge 28 changes over into an undercut or detent surface 30 (FIG. 2) for a holding lug such as bar 31 which stretches between two forked arms 32 extending to the rear of sole 20. The pressure produced by spring 24 provides a sufficiently strong friction bond for the bar 31 in the outline surface 30. The detent surface can be further cut away to increase the attachment.

Torsion spring 33 supported around the hinge pin 26 with one end thereof fixed in arm 25, and the other end pressing the locking element 27, urges the locking element 27 towards its release off of the bar attachment to its limited ofi-position against the'edge 34 of carrier 19 (see FIG. 2). The inclined surface 35 formed on a lock element 27 cooperates with lug 36 which is formed as the end of a right-angle bent arm 37 which in turn is fastened to an adjustably carried holder 38 of sleeve 6. i

The material pressure sole 20 cooperates with the material feed or pusher 40, which executes a so-called skip movement and forms part of the usual feed movement, to displace the sewing goods 39..The materialfeed 40 projects through slit 4] of needleplate 42 and is carried on the material forwarding rod 43. The latter has one end pivotally connected by hinge pin 44 to crank 45 which is fastened to a slide motion translating shaft 46, while its other end is engaged to link guide 48 through hinge pin 47, which is pivotally mounted to crank arm 49. The latter is attached to lift shaft 50 which translates the lifting movement for material pusher 40.

With the execution of the vibratory motion of lift shaft 50, the crank arm 49 lifts and lowers the end of material forwarding rod 43 through link 48 and pivot pin 47 so that rod 43 and the material feed 40 receives a vertical swing movement in addition to its horizontal movement imparted by shaft 46 and pivot pin 44.

So that a safer transport is guaranteed, it is necessary that the teeth of the feed 40 slant to the left as shown in the drawing to engage the sewing goods during its entire stroke above the stitch plate 42. This means that the material feed 40 directly after its passage through the stitch plate 42 passes parallel to the latter, and in its highest position as a result of the described impulses of material forwarding rod 43, will receive a slight tilt- By the'further lifting of the shaft 5, the inclined surface 35 of lock element 27 bears against lug 36 so that the lock element pivots against the force of spring 33. Thereby, the guide surface 28 passes under rod 31 and leads the latter to detent surface 30. There, under the operation of spring24 and the resulting friction be tween bar 31 and the undercut surface, thes'ole is retained and held with its lower side parallel to the needle plate 42. The force of torsion spring 33 is so chosen that it does not overcome the friction between the undercut surface 30 of the lock element and the bar 31.

The sewing goods 39 can now be placed under the sole 20 and the material pressure foot 7 can be lowered back in known way by reversing the hand lever 15. When the seam is started on the material edge 51, the latter must, by the beginning of the sewing, lie under pressure foot 7, as shown in FIG. 2. The pressure of leaf spring 9 operates through material pressure rod 5 on sole 20. The force will be transmitted by linking pin 21 to sole 20. In this way, a torque onthe pressure foot sole 20 develops around the edge 51 laying below needle 2 in the position shown in FIG. 1. A corresponding edge movement of the sole 20 is however prevented by the latch mechanism of lock element 27 and bar 31. Thereby, the sewing goods is pushed forward in the normal way through material pusher 40 and need not be pushed forward against an already slantingly adjusted sole 20.

As soon as the edge 51 of material 39 is forwarded past the sewing axis 21 of the sole 20, it escapes from the action of the torque movement of FIG. 1 by virtue of the parallel sewing goods on the sole. The sole 20 is supported no longer through bar 31 on the surface 30 but rather aligns itself, when the sewing goods 39 no longer lies on one side of the sole 20, parallel to the stitch plate 42 or parallel to the material feed 40.

The slight swing of the sole 20 to a position parallel to the needle plate 42 or parallel to the material feed 40 lifts bar 31 off of surface 30, so that the locking element 27 moves under the action of torsion spring 33 against the edge bearing 34.

The pressure foot sole or apron conforms now to a normal, hinge supported, construction with its known advantages for sewing goods having an irregular upper surface.

When the needleplate 42 provides the loosening means for the locking mechanism between carrier 19 and sole 20, the measurements between the notched surface 30 and bar 31 are so chosen that the lower side of sole 20 in locked position, receives a minimal rising tilt against the tip of the sole and the bar- 31 releases the ing rising in the feed direction. In this way, the sewing goods by transport through the forwarding teeth of material feed 40, will not be pushed together but will be faultlessly transported.

The material pressure foot 7 is raised by horizontally swinging the hand lever 15, which through the shaft 13, the eccentric lug 14, and pivot piece 16 causes surface 18 to engage arm 11 of lifter 10 to lift rod 5 and foot 7. The lifter 10 can besides cooperate in known manner (not shown) with a lifting device which is set in motion by an operators knee.

As soon as the material pressure sole is lifted from the sewing goods or from the needle plate, the sole lays against the stop edge 22 under the operation of spring 24.

locking element 27 in the 20.

When the material feed 40 provides the loosening means for the locking mechanism between the carrier 19 and the sole 20, the measurements between the notches surface 30 and the bar 31 are so chosen that the underside of the sole 20 will be maintained stationary in exactly horizontal position. i

The latter way yields an optimal transport relationship with the start of the sewing. In this case, the locking mechanism of lock element 27 is loosened as a result of the horizontal swing of the sole 20 which is produced through the tilting of the material feed 40 in its highest position of its power drive movement.

I claim:

horizontal position of the sole l. A material pressure foot for a sewing machine of the type having a reciprocating needle sewing means, a needle plate with a slot therein below the pressure foot, which plate supports the material to be sewed, and a material feed means constructed to intermittently move upwardly and rearwardly through the slot in the needle plate to press the material to be sewed against the pressure foot and move said material away from the needle sewing means as it is sewed, the improved construction wherein said pressure foot comprises a carrier and a pressure foot sole hinged to the carrier through an axle positioned behind the needle sewing means,

a first spring means arranged behind the axle which connects the pressure foot sole to the carrier and normally pivotally urges the forward part of the pressure foot sole upwardly,

a locking element pivotally mounted on said carrier and having a lower portion projecting into the path of the rear portion of said sole,

said sole having bar means at the rear end thereof adapted to cooperate with said locking element,

said locking element haivng stop surfaces which, in a first position thereof, cooperate with said bar means to limit the pivotal movement of said'sole about its axle, second spring means mounted on said carrier and normally urging said locking element toward its first position,

said stop surfaces of said locking element including in addition a notched surface which, when said locking element is in a second position thereof, when said presser foot is raised at the beginning of a sewing operation, interlocks said locking element with the bar means and cooperates with the first ment to the forwarding rod and its material-feed device,

and second spring means to hold the sole substan-' tially parallel to the needle plate as material to be sewed is introduced into the machine and to be released from said bar when said material to be sewed is transported beyond the pivoting axle of the sole by the material feed means. 2. The material pressure foot as claimed in claim 1, comprising lifting means adapted to lift the carrier and pressure foot sole,

said locking element having a portion extending above the pivotal mounting on said carrier, said portion ending in a slanting surface, stationary means positioned in the path of said slanting surface whereby upon lifting the carrier and pressure foot the locking element is moved against the action of the second spring to its second position to lock the sole in its intermediate position. 3. The material pressure foot as claimed in claim 1 in combination with a material-feed means constructed so as to cooperate with the material pressure sole, said material feed means comprising arelatively long forwarding rod extending under the stitch plate, the material feed device having teeth for engaging the material i being sewed being carried by the forwarding rod, a slide motion translating shaft linked to one end of the forwarding rod to impart a horizontal oscillating movethe other end of said forwarding rod being linked to a vibratory lift shaft, said material feed rod and shafts being so constructed that the path of the teeth of the material feed move substantially parallel to the stitch plate when extending through the slot in said stitch plate.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3. 776.159 neeember .4, 1913 Inventor Euqen Anqe 1e It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the title page, in the line following "(3o) Foreign Application Priority Data", the date "Mar. 10,

1972" should read June 21, 1971 Signed anci sealed this 16th day of July 1974.

(SEAL) Attest:

McCOY M. GIBSON, JR. I c. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-6 uscoMM-Dc 60376-P69 I v 9 U.S. GOVERNMENT PRINTING OFFICE I969 0366-334

Claims

1. A material pressure foot for a sewing machine of the type having a reciprocating needle sewing means, a needle plate with a slot therein below the pressure foot, which plate supports the material to be sewed, and a material feed means constructed to intermittently move upwardly and rearwardly through the slot in the needle plate to press the material to be sewed against the pressure foot and move said material away from the needle sewing means as it is sewed, the improved construction wherein said pressure foot comprises a carrier and a pressure foot sole hinged to the carrier through an axle positioned behind the needle sewing means, a first spring means arranged behind the axle which connects the pressure foot sole to the carrier and normally pivotally urges the forward part of the pressure foot sole upwardly, a locking element pivotally mounted on said carrier and having a lower portion projecting into the path of the rear portion of said sole, said sole having bar means at the rear end thereof adapted to cooperate with said locking element, said locking element haivng stop surfaces which, in a first position thereof, cooperate with said bar means to limit the pivotal movement of said sole about its axle, second spring means mounted on said carrier and normally urging said locking element toward its fiRst position, said stop surfaces of said locking element including in addition a notched surface which, when said locking element is in a second position thereof, when said presser foot is raised at the beginning of a sewing operation, interlocks said locking element with the bar means and cooperates with the first and second spring means to hold the sole substantially parallel to the needle plate as material to be sewed is introduced into the machine and to be released from said bar when said material to be sewed is transported beyond the pivoting axle of the sole by the material feed means.

2. The material pressure foot as claimed in claim 1, comprising lifting means adapted to lift the carrier and pressure foot sole, said locking element having a portion extending above the pivotal mounting on said carrier, said portion ending in a slanting surface, stationary means positioned in the path of said slanting surface whereby upon lifting the carrier and pressure foot the locking element is moved against the action of the second spring to its second position to lock the sole in its intermediate position.

3. The material pressure foot as claimed in claim 1 in combination with a material feed means constructed so as to cooperate with the material pressure sole, said material feed means comprising a relatively long forwarding rod extending under the stitch plate, the material feed device having teeth for engaging the material being sewed being carried by the forwarding rod, a slide motion translating shaft linked to one end of the forwarding rod to impart a horizontal oscillating movement to the forwarding rod and its material feed device, the other end of said forwarding rod being linked to a vibratory lift shaft, said material feed rod and shafts being so constructed that the path of the teeth of the material feed move substantially parallel to the stitch plate when extending through the slot in said stitch plate.