US2848964A

US2848964A - Feeding mechanisms for sewing machines

Info

Publication number: US2848964A
Application number: US511842A
Authority: US
Inventors: William C Van Ness
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1955-05-31
Filing date: 1955-05-31
Publication date: 1958-08-26
Anticipated expiration: 1975-08-26
Also published as: CH342456A; DE1762839U

Description

Aug. 26, 1958 w. c. VAN mass FEEDING MECHANISMS FOR SEWING MACHINES 2 Sheets-Sheet 1 Filed May 31, 1955 INVENTOR 1 l 1 IIII Will/hm 6. Van Mass Flg l WITNESS W&O C L Aug. 26, 1958 w. c. VAN NESS FEEDING MECHANISMS FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed May 51, 1955 INVENTOR BY William 6. Van Ness AT ORNEY WITNESS wag 1 M FEEDKNG MEQHANIiEih IS FGR SEWING lVlACI-HNES Application May 31, 1955, Serial No. 511,842

2 Claims. ((Cl. 112-215) This invention relates to sewing machines and more particularly to work feeding mechanisms for sewing machines.

It is an object of this invention to provide a drop feed mechanism for a sewing machine in which the work advancing motion of the feeding mechanism occurs in substantially a straight line parallel with the work support.

A further object of this invention is to provide a sewing machine work feeding mechanism arranged to permit convenient access to the sewing machine loop-taker.

Still another object of this invention is to provide a sewing machine work feeding mechanism with parts formed and arranged for lightness without sacrifice of rigidity essential in feed mechanism parts of a high speed sewing machine.

With the above and additional objects and advantages in view, as will hereinafter appear, this invention coinprises the devices, combinations and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

Fig. 1 represents a head end elevational view of a sewing machine with the end cover plate of the sewing head removed and the bed being illustrated in a vertical crosssection and having the work feeding mechanism of this invention applied thereto.

Fig. 2 is a cross-sectional view of a fragment of the sewing head taken substantially along line 22 of Fig. 1.

Fig. 3 is a cross-sectional view of a portion of the mechanism in the sewing head taken substantially along line 3-3 of Fig. 1.

Fig. 4 represents a bottom plan-view of the parts of the Work feeding mechanism disposed beneath the work support.

Fig. 5 represents an enlarged top plan view of a portion of the work feeding mechanism illustrated in Fig. 4.

Fig. 6 illustrates a fragment of the feed dog and includes a diagrammatic representation of a trace of the path of motion of the feed dog.

In the drawings, Fig. 1 illustrates a head end elevational view of a sewing machine having a conventional frame including a bed 11, and a bracket arm 12 rising from the bed and terminating at its free extremity in a sewing head 13. Journaled for endwise reciprocatory movement in the sewing head is a needle bar 14 actuated by way of a driving link 15 from a crank pin 16 carried by a main shaft (not shown) journaled in the bracket arm. A needle 17 carried by the needle bar cooperates in the formation of lock stitches with a loop taker in the form of a rotary hook 18 journaled beneath the bed and actuated from a bed shaft 19 (Fig. 4) which is driven, as by a belt 29, in timed relation with the main shaft of astasat; Patented Aug. 26, 1958 the sewing machine. The hook 18 is of the type including a non-rotatable bobbin carrying case 21 having a latch lever 22 by which the bobbin case may be released from the hook to change or replenish the supply of bobbin thread.

The fiat upper work supporting surface25 of the bed is fitted beneath the needle with a throat plate 26 which is apertured to accommodate the needle as Well as a feed dog 27 disposed beneath the bed and adapted to project upwardly through the throat plate. The feed dog is secured by screws 28-28 to an L-shaped platform 29 formed on a feed bar 30 which is arranged substantially horizontally beneath the bed of the sewing machine. The feed bar is disposed to extend over the rotary hook l8 and is formed with a forwardly extending downturned feed lift arm 31 of which the free extremity is connected by means of a pivot pin 32 with the lower extremity of a short substantially vertically disposed pendant link 33 pivoted by a pin 34 at its upper extremity to the extremity of a rock arm 35 fast on a feed lift rock shaft 36 journaled between

pintle pins

37, 37 carried in

spaced lugs

38, 38 formed in the machine bed and disposed, as is best illustrated in Fig. l, at one side of the rotary hook 18 and at substantially the same level as the axis thereof.

Extending rearwardly from the base of the L-shaped platform on the feed bar is a triangular shaped feed advance arm 39 of which the free extremity is formed with spaced knuckles 4t), 40 apertured to receive a pivot pin 41 which is journaled between spaced

upstanding arms

42, 42 constituting a feed advance rock frame fast on a feed advance rock shaft 43 journaled between

pintle pins

44, 44 carried in

spaced lugs

45, 45 formed in the machine bed. The feed advance rock shaft 43, as is illustrated in Fig. l, is thus disposed at the opposite side of the rotary book 13 from the feed lift rock shaft 36.

The feed lift rock shaft 36 is provided with an actuating rock arm 5% pivoted to a pitman 51 which embraces a feed lift eccentric 52 fast on the bed shaft 19. Also carried on the bed shaft is an adjustable feed advance eccentric 53 of the type disclosed in the U. S. Patent to Myers No. 2,128,031, August 23, 1938, to which reference may be had for a complete disclosure thereof. For purposes of the present invention it will be sufiicient to understand that the eccentricity of the feed advance eccentric 53 may be changed at the will of the sewing machine operator, and by this means, the stitch length of the work feeding mechanism may be adjusted. A pitman 54 embracing the feed advance eccentric is pivotally connected to an actuating rock-arm 55 fast on the feed advance rock shaft 43.

Disposed vertically in the sewing head 13 adjacent the needle bar is a presser bar arranged for endwise movement in a bearing sleeve 61. A presser foot 62 carried on the lower extremity of the presser bar is arranged to overlie the feed dog to cooperate therewith in controlling and feeding of work fabrics therebetween. A leaf spring 63 pivotally secured by a fastening screw 64 to the bracket arm 12 of the sewing machine frame and confined by a pin 65 extending downwardly within the bracket arm is arranged to overlie the upper extremity of the presser bar to bias the presser foot downwardly in opposition to the feed dog while the dog is elevated on its advance stroke and in opposition to the throat plate 26 to grip and control the fabrics while the feed dog is loweredduring its return stroke.

In order that the presser foot may be lifted in opposition to the leaf spring 63 to free the Work fabrics for removal or insertion therebeneath, a manual presser-lifting lever 66 is pivoted at 67 to the sewing head. Overlying the lifting lever 66 is a rearwardly extending arm 69 of a bracket 70 which fits slidably on the upper extremity of the presser bar bearing sleeve. Surmounting the bracket 70 and fast on the presser bar is a collar 71 formed with a rearwardly extending arm 72 slidably disposed in a vertical slot 73 in the sewing head so as to prevent turning of the presser bar. The presserlifting lever 66 when turned upwardly operates through the slidable bracket 70 to engage the collar 71 and raise the presser bar. In addition to the manual presser-lifting lever 66, connections are provided in the machine of this invention whereby the presser foot may be lifted by means of a foot treadle, knee shifter or the like, to this end, a rock frame 74 is pivoted within the bracket arm 12 as by

pivot screws

75, 75. A pin 76 fast on the rock frame at one extremity thereof is connected by means of a pivoted link 77 with the slide bracket 70. At the other extremity of the rock frame is secured an angle bracket 78 pivotally connected with a push rod 79 which depends through the machine frame to a point beneath the sewing machine for connection in any well known fashion with a treadle or knee shifter device (not shown).

Carried on the sewing head 13 of the machine frame is a needle thread tensioning device, indicated generally as 80. This tensioning device is of the spring loaded friction disk type such as is disclosed in the U. S. Patent to Parry et al., No. 2,462,812, February 22, 1949, and is provided with a tension-release pin 81. A cam member 82 fast on the arm 69 of the slide bracket 70 serves to engage and endwise shift the tension-release pin 81 and thereby separate the tension disks when the presser bar is raised either by the hand lifting lever 66 or by the treadle or knee shifter connections.

The feeding mechanism of this invention is of the drop feed variety, that is, the feed dog rising through the throat plate moves forward a predetermined distance, drops below the surface of the throat plate and returns to the starting position, engaging and feeding while the needle is out of the material. In the operation of the work feeding mechanism of this invention oscillation of the feed lift rock shaft 36, and with it the feed lift rock arm 35, imparts rising and falling movement to the forwardly extending feed lift arm 31 of the feed bar 30. As will be apparent from Fig. 1, the vertical movements of the pivot pin 34- on the feed lift rock arm will be transmitted directly to the pivot pin 32 on the feed bar by the short substantially vertical link 33. As the feed advance rock shaft oscillates, however, the advance and return movements of the feed bar imparted by way of the feed advance arm 39 of the feed bar will cause the pendant link 33 to oscillate about the pin 34 in a direction counterclockwise as Viewed in Fig. 1 during the return stroke of the feed bar, and clockwise during the advance stroke. Oscillation of the pendant link, since the link is extremely short, Will give rise to an upward movement of the feed bar at each extremity of the work feeding stroke so that in place of the elliptical path traveled by conventional feed mechanisms, the path of travel of the feed dog of this invention will, be flattened during its advance stroke, that is while the feed dog is elevated through the throat plate and is in engagement with the work. Fig. 6 is a diagrammatic view showing the feed dog, the throat plate and a trace of the path of motion of one point on the feed dog during a cycle of motion. The path of travel as it appears in Fig. 6 occurs in substantially a straight line parallel with the work support during the feed advance portion of the cycle.

As illustrated in Fig. 1, the feed bar 30 of this invention extends over the rotary hook 18 and the feed advance and feed lift arms of the feed bar extend on opposite sides of the loop taker, thereby providing a pendant link construction for the feed mechanism without obstruction of access to the hook. In the operation of a sewing machine having a rotary hook, the under thread mass carried in a bobbin within the hook body must be replenished periodically and it must be changed to match the type of needle thread that is used, as for instance, when the color or size of thread must be changed. As a consequence, convenient access to the bobbin carrying case and to the latch thereof is imperative with this type of machine. The present feed mechanism arrangement provides maximum accessibility to the rotary hook in that it extends over the hook leaving exposed not only the face of the hook but also leaving free the space beneath and to each side of the hook.

An advantage of the present construction resides in the fact that both rigidity and lightness of the feed bar is made possible by this construction providing a pendant link suspension for a feed bar of which the feed advance and feed lift arms extend one from each side of the feed dog. Since the feed dog is supported between the arms rather than in cantilever or other attenuated fashion, a strength and lightness is attained which is highly advantageous in reducing vibration incident to high speed operation of the machine.

Still another advantage is attained by the disposition of the feed lift shaft and the feed advance shaft on opposite sides of the hook shaft. With this arrangement, the two feed actuating shafts may be separated as far as is possible and this fact, coupled with the pendant link, contributes to a very flat feed path of the feed dog above the throat plate.

Having thus described the nature of the invention, what I claim herein is:

l. A feeding mechanism for a sewing machine having a bed provided with a work supporting surface apertured to accommodate the feeding mechanism, and a rotary hook journaled in said bed beneath said work supporting surface, said feeding mechanism comprising a feed bar including a platform disposed between said r0- tary hook and said work supporting surface, a feed advance arm extending from said platform to one side of said rotary hook and a feed lift arm extending from said platform to the opposite side of said rotary hook, a feed dog secured to said feed bar platform and disposed for accommodation through the apertured work supporting surface, a feed advance rock shaft and a feed lift rock shaft journaled in said bed one at each side of the axis of said rotary hook, means imparting oscillatory movement to said rock shafts in timed relation to the rotary movements of said hook, a feed advance rock frame extending from said feed advance rock shaft substantially perpendicular to said work supporting surface, a pivotal connection between the feed advance rock frame and the feed advance arm of said feed bar, a feed lift rock arm extending from said feed lift rock shaft obliquely inclined with respect to said work supporting surface and extending to a position between said work supporting surface and the feed lift arm of said feed bar, and a short link pivoted at one extremity to a point on said feed lift rock arm between said work supporting surface and said feed lift arm and pivoted at its opposite extremity to the feed lift arm of said feed bar, said link being disposed substantially perpendicular to said work supporting surface.

2. A feeding mechanism for a sewing machine having a bed provided with a work supporting surface, and a rotary hook carried on a hook shaft journaled longitudinally in said bed, said feeding mechanism comprising a feed advance rock shaft journaled in said bed to one side of and parallel to said hook shaft, a feed lift rock shaft journaled in said bed on the opposite side of and parallel to said hook shaft, a feed advance rock frame secured to said feed advance rock shaft in a porock arm, a link connecting the free end of said feed 10 2,495,817

6 bar with the free end of said feed lift rock arm, and actuating mechanism for imparting rocking movements to said feed advance rock shaft and said feed lift rock shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,417,865 Smith May 30, 1922 2,231,164 Kaier Feb. 11, 1941 Schulthess Feb. 7, 1950