US2991739A - "teflon" faced shoe for the pressure foot of a sewing machine or the like - Google Patents

Description

July 11, 1961 v' u c. G. JoA 2,991,739

TEELoN EACED SEoE EoR THE PRESSURE FooT 0E A SEWING MACHINE oR THE LIKE Filed Dec. 2, 1957 INVENTOR.

United State 2,991,739 TEFLON FACED SHOE FOR THE PRESSURE FOOT F 'A SEWING MACE OR THE LIKE Curt George Joa, Ocean Ridge, Fla. (Box 1121, Boynton Beach, Fla.) Filed Dec. 2, 1957, Ser. No. 700,039 Claims. (Cl. 112`235) This invention relates to a Teflon faced shoe for the pressure foot of a sewing machine or the like.

Manufacturers of upholstered goods, and others having occasion to use fabrics with high frictional surfaces, have encountered for many years diiiiculties in handling such materials with conventional sewing machines. One plant using fty-iive sewing machines of a well-known manufacturer has, on numerous occasions, had sewing machine engineers come to the plant in an effort to solve frictional problems. The metal shoes with which the machines are equipped are polished as highly as is possible. The engineers suggested that these surfaces be treated with waxes, including silicone wax. While these solved, in part, the problem of high friction, the waxes, when dried, became powdery and created a nuisance and a hazard to the eyes of the operator.

Other eiorts to solve the problem involved incorporating ball bearings, wires and the like in the foot and various arrangements for driving the foot in a manner which it was hoped would relieve the frictional contact of the foot with the work.

After many months of time and thousands of dollars of expense, a solution was found in the provision of a plastic shoe attachment for the sewing machine foot to provide a surface of Teflon, the chemical name of which is tetrafluoroethylene polymer. It is not desired to limit the invention to the particular material bearing the trade mark Teflon since other materials of equivalent characteristics may be substituted. Such materials completely solve the problem of friction and their use does not involve any nuisance or impair in any manner the health of the operator. Such materials are somewhat more subject to wear than the metal foot and hence provision has had to be made facilitating replacement of the shoe sole from time to time. The toe portion of the shoe can be permanently fixed to the fitting and has so little Wear that replacement has not been found to be necessary.

While the invention consists primarily in the use of Teflon or equivalent material to provide a sole surface for the pressure foot, the material is not involved in that aspect of the invention Which concerns the particular means by which the sole is interchangeably applied on a Way with which the foot is provided, being locked in place by a retractable pin, a special fitting being used to retract the pin and to slide a substitute shoe sole into position, the worn sole being ejected as the new sole is applied. Y

In the drawings:

FIG. 1 is a view in side elevation of a sewing machine foot equipped with a shoe in accordance with the present invention.

FIG. 2 shows the parts in front elevation.

FIG. 3 is a view partially in side elevation and partially in section showing the pressure foot `and Worn shoe and showing in side elevation the applying tool and substitute shoe about to displace the worn shoe from t-he foot.

FIG. 4 is a view similar to FIG. 3 in which the tool and substitute shoe are also shown in section and in the course of displacing the used sole member.

rice

FIG. 5 is a view showing in perspective the relatively separated pressure foot and a substitute sole member.

FIG. 6 is a view taken in transverse section on the' plane 6 6 of FIG. 3

FIG. 7 is a fragmentary detail view in plan of a latch pin retracting dowel forming a part of the shoe replacing tool.

Except for the provision of the toe and sole plate members which are made of plastic, the pressure foot organization of the sewing machine remains unchanged. Conventionally this comprises a shank 10. In the particular device illustrated, the fitting 11 at the lower end of the shank is provided with two separate carriers 12 and 13 which are positioned side by side and pivoted to the fitting 11 by a common pintle extending through the fitting at 14. The respective shoes 15 and 16 are pivoted to the carriers 12 and 13 upon individual pintles such as that shown at 17 in FIGS. 1 and 3. Springs such as that shown in dotted lines at 18 are disposed behind the pintle 14, Where they tend to elevate the said ends of the carriers 12 and 13 into contact with an equalizing lever 20 which is pivoted on the shoulder bolt 21 so that any tendency of the Work to raise one of the shoes will bring about a lowering of the other, thus enabling the two shoes to oat side by side upon the work.

In accordances with the present invention, each of the shoes is beveled at its forward end in the manner shown at 22 in FIG. l and FIG. 3. To this beveled forward face is fixed the Teilen toe portion 24 of the shoe with which the pressure foot is provided in accordance with the present invention. The toe portion may be cemented or otherwise permanently fixed to the foot.

Each sole portion 25 has a dovetailed slot at 26 to receive the complementary way 27 provided on the under surface of the foot and desirably extended at 270 on theV under surface of the toe member 24 as shown in FIG. 3 and FIG. 5.

Extending into the front of the shoe through the toe l portion is a longitudinal bore 30 intersected by an upright counterbore at 31 spanned by a pin 32 which provides a seat for compression spring 33. Biased downwardly by the spring 33 is the head 34 of a lock pin 35 which is guided in a hole 36 in the foot 15 and urged into the corresponding hole 37 in the shoe 25 as a means of latching the shoe to the foot during use.

In order to replace the shoe it is only necessary to raise the latch pin 35 su'iciently to clear the shoe 25, whereupon the shoe will readily slide either forwardly or rearwardly along the way 27 until free of the foot.

To facilitate replacement without loss of time by sewing machine operators who may have little or no mechanical skills, I provide the-tool shown in FIGS. 3 and 4. This tool comprises a body member 40- Which is provided with a way at 41 identical with that of the foot 15 to constitute a forward extension thereof. the tool body 40 is mounted a substitute foot 250 engaged by the thrust slide V42 reciprocable along the tool body 40 subject to the control of the handle 43. The

will enga-ge beneath the head 34 of the latch pin to raise ,I

the latch pin in its counterbore 31 against the bias of spring 33. This -frees the shoe 25 so that the advance of replacement shoe 250 can slide shoe 25 from the foot.

Figure 4 shows shoe 25 partially displaced and shoe 250 lPatented I July ll, 1961y Upon the way 41 of 3 has advanced into interlocking engagement with the Way 27 of the foot.

When the slide 42 reaches the limit of movement permitted it, the socket 37 in the replacement shoe 250 will register with the latch pin 35,50 that on Withdrawal of the dowel, the bias of spring 33`will engage the latch pin with the replacement shoe to tix this securely tothe foot.

As'positioned on the foot, the curved lower surface at the forward end of the Teflon shoe will be continued by the curved forward end surface 49 of the toe member 24 to guide the work smoothly beneathV the foot.

The particular material substantially eliminates excessivefriction between the foot and the work, regardless of the character of the work material. Notwithstanding that the Teflon is susceptible to wear, replacement becomes a simple matter in view of the construction of the shoe and the tool as above described.

I claim:

1. The combination with a sewing machine pressure foot member elongated from front to rear in the direction of relative movement l'between the foot and the Work upon which the sewing machine is operating, and a detachable sole member therefor having an elongation corresponding to that of the foot and underlying the foot substantially throughout its length, the sole member providing substantially the entire work contacting surface of said foot, one of said membershaving `a way of less width than the sole member and disposed above and eX- tending longitudinally of said surface and the other of said members having a bearing surface complementary thereto, one of said members having a lock bolt for which the other is provided with a socket adapted to receive the bolt, the engagement of the bolt in the socket releasably securing the sole member against movement along the way respecting the foot member.

2. The combination set -forth in claim-l in which the foot member has at least a surface portion of Teflon 3. The combination'with a sewing machine pressure foot elongated from front to rear of the sewing machinein the normal direction of relative movement between the foot and work upon which the sewing machine is operating and provided with a generally horizontal longitudinally extending way of dovetail cross section, of a workengaging sole member having a dovetail bearing complementary to that of the way and slidable longitudinally of the foot, and a pin retractably mounted in the foot and for which the sole member is provided with a socket, said pin being normally biased to and engaged in the socket solely by its bias to secure the sole member against displacement respecting the foot.

4. The combination with a sewing machine foot member and a sole member therefor mechanically separable i from the foot member by slidingpmovement from therebeneath, one of said members being provided with a dovetail way and the other with a complementary bearing surface for accommodating `such slide movement, the foot member being provided with a tool-receiving socket and with a retractable pin disposed transversely with respect to the socket, and normally in locking engagement with the sole, and having a shouldered portion exposed to engagement by a tool inserted into the socket, whereby when a tool is in the socket said pin is retracted to free the sole member for displacement from the foot member along said way.

5. The combination with an elongated sewing machine foot provided with Ia longitudinal bore and a I,dovetailed way therebeneath, of a sole member in slidably detachable connection with the foot and having a bearing surface complementary to the way, the foot being provided with a hole vertically intersecting the bore and the sole member having a socket normally registering with said hole, a pin retractably mounted in the hole and having means biasing it into normal engagement in the socket to restrain the sole member against sliding movement along the way, the pin being shouldered within said bore.

6. A tool for the replacement of a sewing machine pressure foot sole member, the tool comprising means for supporting and longitudinally propelling a substitute sole member and a dowel projecting longitudinally above the level of the supporting means and provided with a forward end providing a camming surface the supporting means comprising a way of dovetail cross section and the propelling means comprising a slide, the dowel being adapted to position the way of the supporting means with respect to the pressure foot while the slide propels the substitute sole member along the way.

7. As a new article of manufacture, a sewing machine pressure foot sole member comprising a plastic part having a longitudinally elongated undercut bearing surface constituting a way and having a work-engaging bottom face curving upwardly at one end toward the level of said bearing surface.

8. The combination with a sewing machine pressure foot elongated from front to rear of the machine iny the direction of normal relative movement between the foot and the work upon which the sewing machine is operating, said foot being provided with a generally horizontal way of dovetail cross section extending longitudinally 'of the foot in said front to rear direction; of a work engaging sole member having a `dovetail bearing complementary to that of the way and provided with a lower surface of Teflom a pin retractably mounted in the foot and biased downwardly and for which the sole member is provided with a socket, the pin being freely movable in opposition to its bias for release from the socket of the sole member and having a head exposed for camming action to effect movement of the pin in a direction to release the sole member, said pressure foot having tool guiding means for guiding a pin retracting tool upon a path such as to withdraw the pin from the socket.

9. The device of claim 8 in which the pressure foot has a way extending longitudinally from front to rear thereof and constituting the aforesaid tool guiding means, the head of said pin being disposed proximateV said way in the path of a tool guided by said way.

10. In a sewing machine having a pressure foot elongated from front to rear in the direction of normal relative movement between the foot and the work upon which the sewing machine is operating, said foot having a detachable shoe extending longitudinally of said elongated foot and having a sliding front to rea'r connection therewith and adapted to be displaced by a tool having a dowel iior which the foot has. a longitudinal socket; the combination withsaid longitudinally socketed foot and slidably detachable shoe, of a pin having a shoulder within the socket and spaced fromthe bottom thereof, said pin being normally biased downwardly and said shoe having a portion normally engaged by said pin to restrain the Y shoe against displacement respecting the foot, the shoulder of the pin being engageable by the 'said dowel upon its insertion in the socket of the shoe for lifting the pin in opposition to its bias preliminary to thel functioning of said tool upon the sole member.

References Cited in the tile of this patent UNITED STATES PATENTS 47,978 Peterson T- May 30, 1865 765,884 1 Dormandy July 26, 1904 770,008 Holderman Sept. 13, 1904 857,431 Allan June 18, 1907 2,674,036 Butlin Apr. 6, 1954 2,706,460 Grossman Apr. 19, 1955 2,750,697 Jacobson June 19, A1956 '2,814,266 Marshall Nov. 26, 1957 FOREIGN PATENTS 654,308 Germany Dec. 16, 1937 OTHER REFERENCES Dupont Product Engineering Bulletin (3), Article on Teilen pages 1-3 inclusive, 1955, on tile in Division 60.

Images