US2289902A - Presser mechanism for sewing machines - Google Patents

Description

' July 14, 1942. N. v CHRISTENSEN 2,289,902 PRESSER MECHANISM FOR SEWING MACHI NES Filed March 12, 1940 3 Sheets-Sheet 1 sZe INVEZNTOR: Mzrman )[Chn BY WW ATTORNEYS.

WITNESSES: "Zr Mai July 14, 1942, N. v. CHRISTENSEN ,2

PRESSER MECHA NIM FOR SEWING MACHINES y 1942- N. v. CHRISTENSEN 21,289,902

PRESSER MECHANISM FOR SEWING MACHINES s Sheets-Shet 3 Filed Ma rch 12, 1940 ill Illll WITNESSES} INVENTOR: 2 1 iyfirman lf'hristensen,

A TTORNEYS.

Patented July 14, 1942 UNiTE.

PRESSER MECHANISM FOR SEWING MACHINES Norman V. Christensen, Chicago, Ill., assignor to Union Special Machine Company, Chicago, Ill.,

a corporation of Illinois Application March. 12, w ll), Serial No. 323,519 8 Claims. (01. 112-235) This invention relates to presser mechanism useful in connection with sewing machines to hold down the work as it is advanced and stitched in the machines.

In the usual types of presser mechanisms, the presser bar extends up into the needle head and is acted upon either by a helical spring within the head, or by a leaf spring, which, in most instances is mounted on the top of the needle arm and bears on the upper protruding end of said bar. Such usual construction ordinarily entails careful machining of the needle head and bushing of the points where the opposite ends of the presser bar protrude, and moreover, involves the use of relatively heavy parts which are sluggish in their action and which accordingly limit the operative speed of the machines.

One of the aims of my invention is to overcome the above drawbacks. lhis objective I realize in practice, as hereinafter more fully disclosed, in a presser unit which is small, light and compact, and which is designed for attachment to a pendant projection on the needle head, being therefore conveniently accessible at the exterior of the machine frame for the purposes of ready adjustment or replacement.

In connection with a presser unit having the foregoing attributes, it is a further aim of my invention to provide for control of the presser unit for the purpose of facilitating initial insertion of the work and its subsequent withdrawal from beneath the presser foot. This desideratum I realize in practice, as also hereinafter more fully disclosed, in a simple means of which most of the parts, except for the protruding end of an actuating lever at the back of the needle arm, are enclosed and protected within the machine frame.

Other objects and advantages will appear from the following detailed description of the attached drawings wherein Fig. I is a view in top plan of a sewing machine conveniently embodying the presser mechanism of my invention, portions of the machine frame being broken out to expose important parts which would otherwis be hidden.

Fig. II is a view of the machine, partly in front elevation and partly in longitudinal section taken as indicated by the angled arrows II-II in Fig. I.

Fig. III shows the end view of the needle head of the machine with its cover plate removed.

Fig. IV is a fragmentary view, partly in side elevation, and partly in longitudinal section taken axially through the free end of the work supporting arm.

Fig. V is a cross sectional view of the needle arm taken as indicated by the arrows VV in Fig. I; and

Fig. VI is a fragmentary detail view corresponding to Fig. II showing an alternative detail feature of my invention.

The sewing machine herein illustrated for convenience of exemplifying my invention is of the feed off the arm type of the construction disclosed in a copending patent application Serial No. 306,826, filed by me on November 30, 1939. As shown, the machine has a base i from which extends horizontally, a work supporting arm 2 of right angle configuration, and from which rises a standard 3 sustaining a needle arm 3 with a needle head 5 at its free end directly over the free end of said work arm. Partitions 5 and 1 within the needle arm 4 set apart a central chamber 8 between the hollow of the standard 3 and the hollow of the needle head 5; and fitted into said partitions are bearing bushings 9 and Ill for a horizontal shaft ll. As shown, this shaft H extends to the exterior through another bearing bushing l2 in the back side wall of the standard 3 and on its protruding end is provided with a combined hand and belt wheel it; whereby the machine may be manually or power driven. At its left hand end within the head 5, the shaft ll carries a counter balanced crank member l5, which, through a pitman it, imparts endwise reciprocating movements to a vertical needle bar i1 having guidance in inset bushings l8 and i9 at the top and bottom of the needle head 5. Secured in the lower end of the needle bar H is a group of needles 25] (Fig. IV) which cooperate with corresponding loopers 2! on the left hand end of a horizontal shaft 22 within the hollow of the work arm 2. By suitable concealed mechanism within the work arm 2, the shaft 22 is reciprocated endwise and also oscillated for impartation of needle avoiding and loop taking movements to the loopers 2i incident to the formation of chain stitching in a well known way. Also within the work arm 2 is a feed bar 25 which carries a feed dog 26 whereof the toothed portions protrude through longitudinal slots in a throat plate shown at 21 to advance the work forwardly along said arm while it is being stitched. The necessary endwise and lift movements are induced in the feed bar 25 by the aforementioned concealed mechanism within the work arm, said mechanism being in turn operated through suitable concealed connections which includes a train of spur gears 28 (Figs. I and II), from the drive (needle) shaft II. From Fig. II, it will be noted that a spoon 29 on the pitman I dips intermittently into a supply of oil in a sump 30 at the bottom of the needle head to splash about the oil so as to automatically lubricate the needle actuating mechanism.

The presser mechanism which constitutes the subject of my present invention includes a presser foot 3| which is pivotally connected to a shank member 32 at the bottom end of a short vertical presser bar 33, see Figs. II and IV. As shown, this presser bar 33 is supported with capacity for endwise up and down movement in a bracket 34 secured by a pair of set screws 35 to a projection in the form of a rod 36 pendant from the needle head 5. As shown in Fig. III, the upper end of the rod 36 is anchored in the bottom of the needle head 5 and secured in adjusted position by a set screw 31. At its lower end, the rod 36 is provided with a diametrical slot 39 (Fig. II) in which a lateral projection 40 of the shank member 32 is engaged to prevent rotation of the presser bar 33. Bearing on the top of the presser bar 33 is the free end of a small horizontal leaf spring 4| whereof the other end is anchored at 42 in the outer end of a lateral arm projection 43 of the bracket 34. The pressure of the spring 4| is regulatable by means of a cap screw 45 whereof the shank is threaded into a tapped boss 41 on the arm 43 of the bracket 34. The above described presser unit arrangement is advantageous in that it is small and compact, and in that all of its parts are external to the needle head 5 where they are conveniently accessible for the purposes of adjustment or replacement. Since the component parts of the presser unit are small and light, it follows that they will respond quickly to irregularities in the thickness of the work being seamed as it is progressed on the work arm 2 by the feed dog 26 and thus function properly during high speed operation of the machine.

In order that the presser foot 3| may be controlled by means of a knee press or foot treadle (not illustrated) so that the hands of the operator may be left free to manipulate the work during the seaming, I have made further provisions as follows: Disposed within the rear of the needle arm 4 at a level above the shaft II in parallel relation thereto, is a rock shaft with its ends journalled in the partitions 6 and I. From Figs, II anad III it will be observed that the rock shaft 50 extends into the needle head 5 where it carries a horizontal crank arm 5|, which through a flexible connector in the form of a, cable 52, is connected to a screw stud 53 projecting laterally from the presser bar 33, see Fig, IV. As shown in Fig. III, the flexible connector 52 passes through a vertical tube 55 fitted into the bottom of the needle head 5, the height of said tube being such as to insure against escape of oil from within said head. As an alternative, a plunger piece 56 may be interposed, see Fig. VI, in the flexible connector 52, said plunger piece having a sliding fit in the tube 55 to preclude oil leakage from the needle head 5. The rock shaft 50 is operable by means of a lever 51 which extends laterally outward from the shaft 50 through a clearance opening 58 in the back side wall of the needle arm 4, see Figs. I and III, and which is provided with an eye 59 at its outer end for connection by a chain or link with the knee press or foot treadle hereinbefore referred to. As shown in Fig. II, the lever 5'! has a hub or sleeve 60 of considerable length, which at one end abuts the partition 1, and which, in cooperation with a collar 6| on the shaft 50 abutting the partition 6, holds said shaft against endwise displacement. A helical torsion spring shown at 62 (Figs. I anad III) with one end restrained by the rear side wall of the needle head 5 and with its other end hooked over the crank arm 5|, serves to normally maintain the lever 51 in the position illustrated with its top edge bearing against the top of the clearance opening 58 in the needle arm 4 and with the flexible cable 52 slacked so that it does not interfere with the normal action of the presser foot 3|.

The chamber 8 of the needle arm 4 is utilized as a protective housing for the devices 63 (Figs. I, II and V) by which the needle threads respectively designated by the letter T are maintained under tension during the sewing. Each of the devices comprises a pair of opposing disks 64 and 65 between which the thread T passes, said disks being subject to the pressure of a regulatable spring 66 and supported on a horizontal plate 61 at the top of a cross web 68 within the needle arm 4; The control stems 69 of the tension devices 63 pass down through the plate 61 into the path of a wing 10 on the hub 60 of the lever 51 and during the lifting of the presser foot 3| by rocking of the shaft 50, they are concurrently lifted to relieve the tension on the needle threads. Since the tension devices 63, per se, are of well known construction further description of them is deemed unnecessary here. En route from suitable individual sources of supply, the needle threads T enter the chamber 8 through eyes H at the back of the needle arm 4 and after having traversed the tensions 53 emerge through eyes 12 at the front of the needle arm. From thence, the threads T pass through a guide 14 and over a guide hook 15 at the side of the needle head 5 to the needles 20. In the interval between the guide 14 and the hook 15, the needle threads T are acted upon by a take up 16 connected to the needle bar II. All the parts within the chamber 8 are readily accessible upon retraction of a cover 11 which closes an access opening in the top of the needle arm 4.

Although I have shown and described the presser mechanism of my invention as embodied in a feed off the arm sewing machine, it is obvious that it may be used in other types of sewing machines without sacrifice of any of the advantages which have been pointed out.

Having thus described my invention, I claim:

1. In a sewing machine having a frame with a work support and an overhanging needle arm, presser mechanism including a bracket secured with capacity for up and down adjustment to a rigid projection pendant from the outer end of the needle arm; a presser bar guided for up and down movement in the bracket with its upper and lower ends protruding above and below the bracket, a presser foot attached to the lower end of the bar; and a regulatable spring bearing upon the upper end of the presser bar to yieldingly urge the presser foot toward the work support.

2. Presser mechanism according to claim 1, wherein the bracket has a laterally extending arm; wherein the spring is in the form of a tongue anchored in the outer end of the bracket arm with its free end bearing on the top of the presser bar; and wherein a cap screw for adjusting the pressure of the spring has its shank passing down through said spring and threadedly engaging into the bracket.

3. The combination according to claim 1, wherein the needle arm is hollow; wherein the presser mechanism further includes a horizontal rock shaft journaled within the needle arm; a lifting connection extending up from the presser bar and into the outer end of the needle arm to the rock shaft; and means whereby the rock shaft may be actuated from the exterior of the machine frame.

4. The combination according to claim 1, wherein the needle arm is hollow; wherein the presser mechanism further includes a horizontal rock shaft journaled within the needle arm, a flexible lifting cable extending up from the presser bar and through the needle arm to a lifting arm on the rock shaft, and means whereby the rock shaft may be actuated from the ex terior of the machine frame.

5. The combination according to claim 1, wherein the needle arm is hollow and has an oil sump at the bottom of its outer end; wherein the outer end of the arm contains needle actuating mechanism lubricated with oil taken from the sump; and wherein the presser mechanism further includes a horizontal rock shaft journaled within the needle arm, a flexible cable lifting connection extending up from the presser bar to an arm on the rock shaft, a plunger piece interposed in the cable, and a bushing set into the bottom wall of the needle arm in which the plunger piece has a sliding fit.

6. In a sewing machine having a base with a work support, a hollow overhanging arm terminating in a needle head above the free end of the work support, and a needle bar guided for up and down movement in the needle head; needle bar actuating mechanism within the head lubricated by splash action from an oil sump at the bottom of the head; presser mechanism comprising a presser element guided for up and down movement exteriorly of the head, and means whereby the presser element may be lifted when necessary in introducing the work beneath it including a rock shaft which extends longitudinal- 1y of the arm aforesaid and into the needle head, a lever arm on the shaft within the head, a connection extending from said lever arm down through a tube within the head to the presser element, the top of said tube being above the oil level and out of the range of the oil splash, and an operating lever on the rock shaft within the compartment extending outward through a clearance opening in the wall of said overhanging arm.

7. In a sewing machine having a base with a work support, a hollow overhanging arm terminating in a needle head above the free end of the work support; a needle bar guided for up and down movement in the needle head; a shaft within the arm; needle bar actuating mechanism within the head driven from the shaft and lubricated by splash action from an oil sump at the bottom of the head, a partition separating the hollow of the head from an adjacent oil tight compartment within the overhanging arm, and a needle thread tension within the compartment; presser mechanism comprising a presser element guided for up and down movement exteriorly of the head, means whereby the presser element may be lifted when necessary in introducing the work beneath it including a rock shaft which extends longitudinally of the compartment aforesaid and into the needle head, a lever arm on the shaft within the head, a connection extending from said lever arm down through a tube within the head to the presser element, the top of said tube being above the oil level and out of the range of the oil splash, an operating lever on the rock shaft within the compartment extending outward through a clearance opening in the wall of said overhanging arm, and means also on the rock shaft for controlling said thread tension concurrently with lifting of the presser element.

8. The combination according to claim 1 wherein the needle arm is hollow; wherein the presser mechanism further includes a horizontal rock shaft journalled within the needle arm; a lifting connection operable in tension only extending up from the presser bar and into the outer end of the needle arm to the rock shaft; and means whereby the rock shaft may be actuated from the exterior of the machine frame.

NORMAN V. CHRISTENSEN.

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