US3338196A

US3338196A - Blindstitch sewing machine

Info

Publication number: US3338196A
Application number: US411860A
Authority: US
Inventors: Gerald C Roth
Original assignee: Union Special Machine Co
Current assignee: Union Special Machine Co
Priority date: 1964-11-17
Filing date: 1964-11-17
Publication date: 1967-08-29
Anticipated expiration: 1984-08-29
Also published as: DE6606912U

Description

G. C. ROTH Aug. 29, 1967 BLINDSTITCH SEWING MACHINE 6 Sheets-Sheet 1 Filed Nov. 17, 1964 G. C. ROTH Aug. 29, 1967 BLINDSTITCH SEWING MACHINE 6 Sheets-Sheet 2 Filed Nov. 17, 1964 FIG2.

FIGS.

Aug. 29, 1967 G. c. ROTH' 3,338,196

BLINDSTITCH SEWING MACHINE Filed Nov. l'7, 1964 6 Sheets-Sheet 3 G. C. ROTH Aug. 29, 1967 BLINDSTITCH SEWING MACHINE 6 Sheets-Sheet 4 FiledNoV. 17, 1964 Aug- 29, 1967 G. c. ROTH 3,338,196

BLINDSTITCH SEWING MACHINE Filed Nov. l?, 1964 6 Sheets-Sheet 5 Aug. 29, 1967 G. c. ROTH BLINDSTITCH SEWING MACHINE 6 Sheets-Sheet 6 Filed NOV. 17, 1964 United States Patent Olice 3,338,196 Patented Aug. 29, 1967 ABSTRACT F THE DISCLOSURE A blindstitch sewing machine having a node forming mechanism of such construction and mode of operation as to maintain the node former in its active position throughout the time that the needle is engaged with the work. More particularly, the node former is shifted vertically into and out of its active position by dwell camming means driven by the main shaft of the machine in a manner to retain the node former in its active position throughout the period mentioned. This requires retention of the node former in the active position during about 140y to 180 of each revolution of the drive shaft of the machine.

This invention relates to blindstitch sewing machines and more specifically to the mechanism in such machines for operating the node former. It is particularly concerned with problems involved in the use of such machines for applying a binding tape, in blindstitch fashion, to a carpeting material having a layer of bers at the upper surface thereof with a synthetic rubber or hard rubber backing secured adhesively or otherwise to the under surface of the composite material.

Various difliculties have been encountered heretofore in the use of conventional blindstitch machines for the purpose indicated. It has been found that in the use of such conventional machines there has resulted the frequent breakage of the curved needles in performing the seaming operation and also the ripping or cracking of the relatively stiff rubber-like backing material now frequently used for carpets. Such backing materials employed for present day carpeting are very often formed of hard rubber or synthetic rubber having similar characteristics. Careful studies have shown that the diculties have arisen from the fact that the node former, as heretofore embodied in such machines, has been withdrawn from its node forming position before the needle has become disengaged from the node formed by the node former. This has resulted in the downwardly movement of the node in the material into a substantially horizontal position against the supporting surface of the presser foot or the likebefore the needle is disengaged from the material. The downward force thus applied to the curved needle, especially when the material being operated upon is relatively thick and stiff, is such as to cause frequent breakage of the needle. In many instances, where the backing material, facing7 upwardly from the path of the needle, is relatively stiff, because of the use of a rather thick coating 4of backing material, this has resulted in ripping or shearing of said backing material, as the node is drawn downwardly by the relatively stiff rubber backing material with a detrimental nal product. This is particularly true in connection with the modern trend toward the use of relatively stiff rubber backing materials.

In accordance with the present invention the foregoing diiiiculties are overcome by a special timing of the operation of the node former. Provision is made Afor a substantial period of time during which the node former remains active to retain a node in the material being stitched in the path of the curved needle. The preferred arrangement is such that the node is firmly held in its elevated position during about 180 of revolution of the main shaft of the machine. This makes it possible to insure that the node former positively retains a node in the work along the path of travel of the curved needle throughout the time that the latter is engaged with the work. As a result, no appreciable bending force is applied to the needle by the material being stitched at any time during a cycle `of operation of the machine. This is because there is no opportunity for the material being stitched to move away from the path of the needle whileV the latter is engaged with the work. Thus the two objectionable results from the operation of prior node forming mechanism is completely eliminated, and a uniform blindstitch seam is provided in the work.

Toward the foregoing end, the present invention includes the provision of connections from the main drive shaft of the machine to the node former which will retain the latter in its active node producing position sol tending toward a point at a smaller radial distance from` the axis of rotation of the cam. It should be understood that the surface of the cam is not at in any region, but is smoothly curved at all points to provide the triangular effect. By virtue of this construction of the cam, the node former is moved into its active position during about a revolution of the cam, is held in its active position during about a revolution of the cam, and is returned to its inactive position during the remaining 90 revolution of the cam.

The special cam described above cooperates with a rectangularly shaped pitman head which carries a roller at its upper end cooperating with the outer surface of the cam. Such pitman is urged downwardly by a spring to retain said roller in cooperation with the cam surface, the arrangement being such that the pitman is held in its uppermost position during about 180 of revolution of the cam but is permitted to move downwardly during another 90 revolution of the cam and is then moved upwardly to its uppermost position during the next 90 revolution of the cam.

A member mounted on the drive shaft, but not rotatable therewith, is provided with vertically disposed surfaces cooperating with similarly disposed vertical surfaces carried by the head of the pitman to retain the latter against horizontal movement by the cam, so as to insure simply vertical reciprocation of the pitman.

Another feature of the invention, with the foregoing objective in mind, is the provision of node former actuating mechanism which may be readily adjusted in its timing action to insure proper timing of the stroke and dwell of the node former to make certain that the node is held upwardly in the path of the needle throughout the period during which the needle is engaged with the work. The construction is such, moreover, that adjustment of the height of the node former during its active dwell position may be readily effected, so as to maintain the node formed in the material at the desired elevation, depending upon the thickness of the material being stitched, throughout the time that the needle is engaged with the work.

Other features and advantages of the invention will appear from the following detailed description of a pretending longitudinally through the frame structure of the machine, showing various operating parts carried by the frame;

FIG. 2 is a transverse vertical sectional view taken along the staggered line 2-2 of FIG. 1;

FIG. 3 is a detail view, showing in front elevation the foremost work feeding device embodied in the machine;

FIG. 4 is a detail view, in front elevation, of the rearmost work feeding device embodied in the machine;

FIG. 5 is a end elevational view of the lower portion of the machine, taken along the line 5 5 of FIG. l;

FIG. 6 is a bottom view of a portion of the machine with certain parts shown in section;

FIG. 7 is an exploded perspective View of the node former and its supporting means and a portion of the means for shifting the node former into and out of active position;

FIG. 8 is a diagrammatic view showing the relationship of certain parts embodied in the node former operating mechanism;

FIG. 9 is a detail view, in elevation, showing parts incorporated in the node former operating mechanism and the adjusting means therefor;

FIG. 10 is a detail view showing in section along the line 10--10 of FIG. l an element shown in FIG. 9;

FIG. 11 is a plan view of the upper end of the pitman which operates the node former;

FIG. 12 is a yface view of the upper end of the pitman, Y

with the main operating shaft of the machine shown in section;

FIG. 13 is a face View of the cam which drives the pitman;

FIG. 14 is a side View of the cam shown in FIG. 13;

FIG. 15 is a perspective view of a roller, having needle bearings incorporated therein, carried at the upper end of the pitman;

FIG. 16v is a perspective view of a guide block freely carried yby the drive shaft and cooperating with surfaces at the upper end of the pitman to retain the same against horizontal movement in relation to the shaft;

FIG. 17 is a perspective View of an element forming a part of the upper end of the pitman; and

FIG. 1S is a diagrammatic view showing the relative timing of the needle and the node former incorporated in the lmachine of the present invention.

The blindstitch machine illustrated in the foregoing drawings is of the general character of that shown in the patent to Bowman No. 2,280,468, granted Apr. 21, 1942. The primary differences between the machine constructed in accordance with the present invention and that disclosed in the said Bowman patent are in the nature of the driving connections from the main shaftof the machineV to the node former for imparting to the latter the particular timing of movements described above.

Referring now to the drawings, the improved machine comprises a main frame having a base portion 10, a vertical standard 11 and an overhanging arm 12. 'Ihe latter carries downwardly extending frame elements 12a and 12b which support various parts of the mechanism to be described. A main drive shaft 13 is suitably journalled in bearings 15 and 16 to extend longitudinally of the overhanging arm. At its right end (FIG. l) the shaft 13 has secured thereto a combined hand wheel and pulley 14. As will be understood, the pulley is adapted to be connected by a belt to an electric transmitter or other power source for normal operation of the machine, while the hand wheel portion of member 14 enables manual turning of the drive shaft for adjusting the position of the various parts of the machine Whenever desired.

Suitable driving connections are provided from the shaft 13 to various mechanisms that are operated during the stitch forming operation of the machine, these mechanisms including work feeding rollers, an oscillatory needle, complementary stitch forming means, such as a rotary hook, a looper and spreader mechanism, and a node 4 v former for creating a node in the work in the region of the stitch forming devices at appropriate times during the operation of the machine. Y

The connections from the main drive shaft for intermittently turning the top feed rollers, which urge the work against a stationary presser foot or similar work supporting surface on the base portion of the frame of the machine, preferably including freely rotatable rollers, are operated by spherical eccentrics 17 and 18 secured to the shaft 13. Cooperating with the eccentric 17 is a spherical strap portion at the upper end of a pitman 19. Similarly, cooperating with the eccentric 18 is a strap at the upper end of a pitman 20. The lower ends of these two pitmans are connected with feed operating levers or arms which serve to drive ratchet wheels 21 and 22, respectively, through pawls. Means of this character, suitable for the purpose, are disclosed in said Bowman patent. As there shown, the arrangement is such that the extent of feed movement of the feed rollers may readily be varied to conform with a selected stitch length. Thus as shown in FIG. 4, the ratchet wheel 21 is secured to a shaft 21a which carries at its other end a group of feed wheels or rollers 2lb. Similarly, as shown in FIG. 3, the ratchet wheel 22 is secured to a shaft 22a which carries at its other end a plurality of feed wheels or rollers 22h. The two groups of feed wheels or rollers may be substantially alined in relation to each other along the line of feed of the work in the region in which it is being stitched. Thus the wheels 2lb are disposed rearwardly of the wheels 2217. 'Ihese two sets of wheels may also, if desired, be displaced to a certain extent laterally in relation to each other in the direction of feed.

For driving the needle of the stitch forming mechanism there is provided a spiral gear 23 secured to shaft 13 which cooperates with a spiral gear 24 secured to a shaft (not shown) having a counter-weighted crank member 25 secured thereto which carries an eccentrically mounted wrist pin 25a. The latter is connected with a pitman 26 for imparting reciprocatory movements to the pitman. An arm 26a of the pitman extends rearwardly from and is connected with a pin 25b which is slidably mounted on an arm (not shown) adapted for oscillatory movement about a xed axis, as shown in the Whitelaw Patent No. 1,- 176,415. (See FIG. 2 of said patent.) By these connections the various parts are confined to their proper paths of movement, and the arm 26a serves to operate a needle thread take up member (not shown). The lower end of pitman 26 is pivotally connected with an arm 27 extending rearwardly from an oscillatory yoke or needle carrier 28. The latter is preferably of U-shaped configuration and is adapted for swinging movements about studs 29 carried by the frame. Extending forwardly and downwardly from the yoke 28 is a needle clamping portion 28a adapted to retain a curved needle 30. It will be apparent from the foregoing, and from the showing in FIG. 1, that the needle 30 will be swung through an arc in a vertical plane disposed at an .acute angle, of say 45, to the vertical plane along which FIG. 1 is taken. The work is advanced in a direction perpendicular to said plane.

Cooperating with the needle 30 to form lines of stitching of the character disclosed in the above-mentioned Bowman patent is a rotary hook 31 with which loopers or spreaders, not shown, cooperate to form the stitching.V

Reference may be made to the above-mentioned Bowman and Whitelaw patents for details of the construction, arrangement and operation of the complementary stitch forming devices. It may be Vbriefly stated here that they are driven from the shaft which carries the spiral geal 24, through a second spiral gear 32 secured to said'shaft.

The Various stitch forming elements are suitably mounted. on the members 12a and 12b of the frame structure. Through the cooperation of the needle 30 and the rotaryhook and the looper or spreader elements disclosed in the patents referred to, a seam of either of the types illustrated in the Bowman patent may be produced.

Referring now particularly to FIGS. 5 and 6, the caI- peting material being stitched is advanced by the feed wheels 21'fb and 22b over the surface of the presser foot structure 34. This structure includes a forward supporting roller 33 and a pair of rearward supporting rollers 34a and 34b. These Irollers and the member 34 are normally held in an elevated position, which is subject to some adjustment, to retain the carpeting material in engagement with the feed wheels or rollers 2lb and 22h. Provision is made for lowering the presser foot elements mentioned, whenever it is desired to introduce the work into or remove the work from the machine. Before describing this mechanism, however, it is desired to mention that a node former 35 is provided for vertical movement in the region of the arc through which the curved needle 30 is swung, so as to present a node of the work in the path of the needle. A groove 35a is provided atl the top of the node former for the passage of the needle therethrough. The node former has a laterally extending stem 36 mounted in the manner to be described in a node former carrying and actuating member.

The mechanism for lifting, lowering and adjusting of the presser foot structure will now be described. There is shown a shaft 37 (FIG. 6) suitably journalled in the main frame of the machine. Outwardly of said frame the shaft 37 carries a member 38 which extends rearwardly toward the node former and has a free end portion 38a parallel with the node former in a region adjacent the latter. Member 38 is secured to shaft 37 by means of a pair of screws 39. The work supporting rollers 34a and 34b are carried by a rock arm 40 having a hub portion 40a which is journalled upon a stud 41 secured by a set screw 41b in a recess provided in the main frame of the machine. A screw 41a having threaded engagement with the stud 41 serves to retain the hub portion 40a on the Vstud 41 for free rocking movement thereabout. A connecting link 42 is pivotally connected with the rock arm 40 by means of a screw 42a, and its other end is pivotally connected by a screw 42b with a downwardly extending portion of the rock member 38. This arrangement is such that the two rock members 38 and 40 will be operated in unison to retain the rollers 33 and 34a, 341g at the appro# priate level for cooperation with the Work being fed through the machine. Secured to the shaft 37 is an arm 43 (FIGS. 2 and 6), this being retained' in adjustable position in relation to the shaft by screws 43a. A spring 44 attached to the outer end of the arm 43 serves to rock the latter in a counterclockwise direction (FIG. 2). The upper end of spring 44 is carried by a hook element 45 which is adapted for vertical adjustment to vary the tension of the spring.

Any suitable means may be provided for limiting the extent of upward movement of the presser foot members, including rollers 33 and 34a, 34b. Such means may comprise, for example, an adjustable stop element 46 (FIG. 6) carried by an arm 47 secured by set screws 48 to the right-hand end of shaft 37. Element 46 is .an adjustable screw having its free end adapted to cooperate with the lower surface of a horizontally extending portion Vat the top of the base of the frame member of the machine.

Means are provided for rocking the shaft 37 under control of the operator to bring about lowering of the presser foot structure, including the rollers 33, 34a and 34b. This is to facilitate the introduction and removal of the work to be stitched. The means for so rocking the shaft 37 comprises la rock shaft 49 (FIG. 6) which is journalled in suitable bearings in the base of the frame and extends forwardly of the front face of the base. To the projecting end of shaft 49 a knee press member of conventional form is attached, to enable the operator to rock the shaft 49 by shifting of the knee slightly toward the right. Secured to the shaft 49 is an arm 50 having a hub portion provided with set screws 51 for firmly attaching the arm to the shaft 49. An extension 50a of the arm 50 cooperates with extension 47a of the arm 47. Ex-

tension 50a is preferably disposed a slight distance above the extension 47a, so that the knee press member will not be affected by the slight rocking of the arm 47 which -may take place during operation of the machine as -a result of varying thicknesses of the work being stitched.

The node former 35 has its stem 36 extending into a laterally projecting arm 52a of a cradle member 52. The stem 36 is retained in a suitably adjusted position in relation to the arm 52a by means of set screws 52b. The main body portion of cradle member 52 has a relatively large diameter cylindrical opening therethrough to receive a supporting element 53 which is eccentrically mounted upon .a shaft 54. This shaft is suitably journalled in a bearing portion 54a (FIG. 6) of the base of the frame and in a bushing 54b carried by the frame. Shaft 54 is normally held stationary, but it is adapted for slight angular adjustment in a manner to be explained. As most clearly shown in the exploded perspective view, FIG. 7, the right-hand end of the shaft 54 extends through a slide block 55 having a cylindrical opening 55a therein. Within the opening 55a there is disposed an eccentric element 56 provided with an opening 56a through which the shaft 54 extends in eccentric relation to the opening 55a of block 55. Eccentric 56 is secured to the shaft 54 by a set screw 56b, FIG. 2. The block 55 is arranged for sliding movement within a forked member 57 having opposed surfaces 57a along which the block 55 may slide to a limited extent. Member 57 is secured to the member 52 by means of a screw stud 58 having a cylindrical portion cooperating with a cylindrical opening 57e extending through member 57. 'Ihe threaded end portion of stud 5S cooperates with a threaded opening 52b in a laterally extending arm 52e of cradle member 52. A forwardly extending portion 57b of member 57 is provided with an opening yadapted to receive a stud 59 provided with a spherical head portion 59a. This stud is retained on extension 57h by a nut 59b. Cooperating with the spherical head 59a of the stud is a strap 60a provided at the lower end of a pitman 60, as best shown in FIG. 2. At the upper end of pitman 60 there is secured thereto a head portion designated generally as 61, this head portion being arranged to cooperate with a dwell cam member 62 to be hereinafter more fully described. Cam member 62 has a cylindrical portion 62a (FIGS. 1, 13 and 14) at one end thereof adapted to receive set screws 63 which serve to attach the cam member to the shaft 13 which passes through the bore of the cam member, shown in dotted lines in FIG. 14. The caming portion of the member 62 has a semi-cylindrical outer surface 62b extending over an are of about in the region shown at the top in FIG. 13. The remaining, lower surface 62e of the cam member has the contour shown in FIG. 13, so that yas viewed from the left in FIG. 14 the cam as a whole has about half of its circumference at the same radial distance from the axis of the shaft 13 and the remaining part of its circumference decreases in its radial distance from the axis of shaft 13 from the two ends of portion 62b to the lowermost point shown in FIG. 13 of surface 62e.

The head portion 61 of the pitman 60 has a part 64 provided with .a cavity adapted to receive and surround the cam member 62. This part 64 is provided with an opening 64a communicating with the cavity mentioned. A pin 65 mounted in the upper end of part 64 carries a roller 66 (FIGS. 11 and 15) having at its center a needle bearing 66a adapted to permit free rotation of the roller about the pin 65. On one face of the part 64 of member 61 there is mounted a U-shaped element 67 provided'with cylindrical openings 67a and 67b. These openings are adapted to receive attaching bolts 68 and 69 which serve to secure element 67 to the part 64. Mounted on the shaft 13 is a block 70 having vertically extending surfaces 70a at its opposite sides, these surfaces being adapted to cooperate with adjacent surfaces 67c of element 67. On one face of the block 70, as best shown in FIG. 16,

asp-salasL there is provided a pair Vof laterally extending flanges 70b. These are arranged to cooperate with the surfaces 67d of element 67. It will be appreciated that member 70 serves to guide the upper part 64 of the pitman 60 during the vertical movements of the latter and serves to retain the pitman in vertical alinement.

A spring 71 (FIG. 1) is connected at its upper end with a screw stud 72 carried by the head portion 61 of the pitman 60. At its lower end the spring 71 is connected with a bolt 73 rmly secured to the vertical portion 11 of the frame of the machine by means of a nut 74. Nuts 75 are also provided on the bolt 73 for retaining the lower end of the spring 71 in proper position. It will be apparent that the force of the spring 71 serves to retain the roller 66 at all times in engagement with the periphery of the cams 62h, 62e. Thus the upward and downward movements of the node former 35 during the rotation of the shaft 13 are electively controlled.

Provision is made for varying slightly the vertical position of the node former, i.e. the location of its upper end in relation to the work as it is shifted upwardly and downwardly by the cam surfaces 62b, 62C. For this purpose a link 76 is provided, this being connected by a stud 77 to the enlarged end 78 of member 53. A set screw 79 (FIG. serves to retain the stud 77 in the enlarged end 78 of member 53, and set screws 80 serve to connect this member for turning movement with the shaft 54. At its upper end the link 76 is connected by a screw stud 81 with the lower end of a sleeve 82 mounted within a tubular portion 83 of the member 11 of the frame of the machine. The internal surface of sleeve 82 Vis threaded to receive the lower threaded end of a screw stud or bolt 84 which is mounted for -rotation in a cap 85 secured by screws 86 to the upper end of the tubular portion 83 of the frame. At its upper end the bolt 84 has secured thereto, by a set screw 87a, a knurled hand wheel or knob 87. The latter may be turned readily by the operator and is held in any adjusted position by a spring urged plunger 88 cooperating with serrations or teeth provided around the under surface of the knob 87. Longitudinal movement of the bolt 84 is prevented by the knob 87 and a ange 84a at opposite faces of the cap 85. It will be apparent that when the knob is turned the stud 84 will be rotated and the threads thereon, cooperating with the internal threads of sleeve 82, will cause the latter to move upwardly or downwardly, depending upon the direction of rotation Vof the knob. Such movements of the sleeve 82 are transmitted through the link 76 to the member 78, andV through the latter serves to rotate the shaft 54 to a desired limited extent. From FIG. 2 it will be noted that if the shaft 54 is turned slightly in a counterclockwise direction the eccentric 56 will serve to lift the slide block 55 slightly and correspondingly lift the stud 58 and the extension 52e of the cradle 52 that carries the node former. It will be appreciated that during such adjustment the stud 59, with which the lower end of pitman 60 cooperates, will be held in fixed position. Turning of the member 56 in the opposite direction, through the connections described from the knob 87, will rock the node carrying cradle 52 slightly in the opposite direction. As the eccentric 56 is thus turned slightly in one direction or the other, the cradle supporting eccentric 53 will also be correspondingly turned within the cradle 52, thereby imparting a bodily upward or downward movement to the cradle. ln this way iine adjustment of the node former and the lower and upper ends of its vertical path of movement may be elected.

In connection with the foregoing, attention is directed to FIG. 8. As there shown, counterclockwise movement of shaft 54 will cause counterclockwise movement of member 57 to rock the cradle 52 slightly clockwise (FIG. 7). Simultaneously the cradle supporting eccentric 53 will cause some lowering of the axis about which the cradle 52 is rocked. It has been found desirable to so connect the eccentric 53 and the eccentric 56 with the shaft 54 that a line from the axis of the latter to the point of maximum eccentricity of eccentric 53 is about 158 counterclockwise of the line connecting the axis of shaft 54 with the point of maximum eccentricity of the eccentric 56. This specific relationship between the parts mentioned may be varied to some -extent in achieving the purposes of the invention.

Referring to FIG. 18 there is shown a desirable relative timing of the needle movement, the node former and the work feeding mechanism of the machine during a cycle of operation of the machine. As there shown, the needle is in its right-hand position at the beginning of a cycle of the machine, i.e. the 0 position of the parts. The needle shifts toward the left during the'iirst 180 revolution of the drive shaft and shifts toward the right during the remaining 180 revolution of said shaft. The node former has lifted the work into the path of the needle by the time the latter has shifted to the position toward the left. By virtue of the dwell cam operating means for the node former the latter is held in its active position until the needle has been returned toward the right, out of engagement with the work, by the time the drive shaft has reached about 255 of its cycle of revolution. As the node former is moved downwardly from the work the latter is no longer engaged with the needle so that no damage to either the needle or the Work occurs. The work feeding mechanism begins to advance the Work for the next stitch at about the 290 point in the cycle of revolution of the drive shaft, and such feeding of lche work is discontinued at about the 40 point in the next cycle of operation of the drive shaft. This is prior to the node forming action on the work during such next cycle. As a result, no bending force is applied to the needle, and no strain is applied to the work, at any time during engagement of the needle with the work.

As indicated in FIG. 18, the node former is held in its active or most elevated position during about 150 of lrevolution of the drive shaft. This arc of revolution may be varied between and 180 to achieve the desired purpose, it being understood that the contour of cam 62 may be selected to bring about the desired length of this arc.V

By appropriate adjustment of either or both the crank member 25 and cam 62 in a circumferential direction about their supporting shafts the relative timing of the needle movement and the dwell and stroke of the node former may be varied to any extent desired for the best functioning of the mechanism.

While a preferred construction -of the machine for accomplishing the foregoing result has been disclosed in detail, it will be understood that various changes may be made in the overall construction to achieve the desired purposes of the invention.

What is claimed is:

1. In a blindstitch sewing machine, work feeding means, an oscillatory curved needle, complementary stitch forming means cooperating with said needle to form a line of stitching, a shiftable node former adapted to cooperate with the work to form a node therein in the path of said needle, a main drive shaft, and connections from said drive shaft for Operating said work feeding means, said needle, said complementary stitch forming means and said node former, said connections for operating s aid node former comprising a dwell cam having a semi-cylindrical surface and being adapted to shift the node former into and out of its active node forming position, said last mentioned connections being so constructed and arranged that said semi-cylindrical surface retains said node former in its fully active position throughout the time that the needle is engaged with the work.

2. In a blindstitch sewing machine as set forth in claim 1, said last mentioned connections being adapted to retain said node former in its fully active position during about 140vto 180 of each revolution of said drive shaft.

3. In a blindstitch sewing machine as set forth in claim 1, means for supporting said node former arranged to shift the latter substantially in a vertical direction into and out of its active position.

4. In a blindstitch sewing machine as set forth in claim 3, said means for supporting said node former comprising a rockable cradle member, said node former being attached to said cradle member in a region thereof spaced substantially horizontally from the axis about which said member is rocked.

S. In a blindstitch sewing machine as set forth in claim 4, said cradle member being rockable about a carrying member having cylindrical surfaces cooperating in bearing relation with cylindrical surfaces on said cradle member.

6. In a blindstitch sewing machine as set forth in claim 5, said carrying member being mounted for turning movement about an axis eccentric to the axis of the cylindrical surfaces on said carrying member.

7. In a blindstitch sewing machine as set forth in claim 6, means for adjustably turning said carrying member about said eccentric axis and retaining said carrying member in its adjusted turned position.

8. In a blindstitch sewing machine as set forth in claim 7, said connections from said drive shaft for operating said node former comprising a rock member, means adjacent one end of said rock member for supporting the same for rocking movement, means adjacent the opposite end of said rock member for connecting the same with a pitman, a cam on said drive shaft for cooperating with said pitman to impart longitudinal, reciprocatory movements to the latter, said cam being provided with an arcuate surface extending over an arc of at least about 140 for retaining said pitman at one end of its movement during rotation of the drive shaft through said arc, and connections from an intermediate point on said rock member to said cradle member for rocking the latter.

9. In a blindstitch sewing machine as set forth in claim 8, said means for supporting said rock member adjacent said one end thereof comprising an eccentric interconnected with said carrying member in alinement with the eccentric axis thereof, a slide block carried by said eccentric slidable on retaining surfaces provided on said rock member.

10. In a blindstitch sewing machine as set forth in claim 9, said eccentric having its point of maximum eccentricity disposed along a line extending from the axis about which said eccentric is turned that is inclined at about 148 to the line extending from the point of maximum eccentricity of said carrying member to the axis of rotation of said carrying member.

11. In a blindstitch sewing machine as set forth in claim 9, a shaft to which said eccentric and said carrying member are secured, the points of maximum eccentricity of said eccentric and the cradle member supporting surfaces of said carrying member being disposed in such angular relation to each other as to cause lifting and lowering of the node former as said shaft to which said eccentric and said carrying member are secured is turned in one direction or the other.

12. In a blindstitch sewing machine as set forth in claim 11, said connections from said drive shaft to said needle and to said node former being adjustable to enable the ready variation in the relative timing of the movement of said needle and the movement of said node former.

13. In a blindstitch sewing machine as set forth in claim 3, spring means for normally urging said node former into its lowermost position, and means connected with said drive `shaft for lifting said node former into its uppermost and active position against the action of said spring.

14. In a blindstitch sewing machine as set forth in claim 13, said means for lifting said node former into its active position comprising a vertically movable pitman and cam means on said drive shaft for opposing the force of said spring, said cam means having a dwell portion of maximum radial extent serving to retain said node former in active position during at least of rotation of said cam means, and means cooperating with said pitman for confining it to vertical movement.

15. In a blindstitch sewing machine as set forth in claim 14, said pitman carrying a freely rotatable roller at its upper end cooperating with the peripheral surface of said cam.

16. In a blindstitch sewing machine as set forth in claim 14, said means for retaining said pitman for vertical movement comprising a block freely mounted on said drive shaft, said block having surfaces thereon cooperating with surfaces on said pitman.

References Cited UNITED STATES PATENTS 1,059,966 4/ 1913 Arbetter 112-177 1,069,010 7/1913 Hemleb 112-177 1,176,415 3/ 1916 Whitelaw 112-177 1,260,193 3/1918 Hayes 112-177 1,287,157 12/ 1918 Whitelaw 112-178 1,947,950 2/ 1934 Mueller 112-178 2,280,468 4/1942 Bowman 112-178 3,105,450 10/1963 Taylor 112-178 JORDAN FRANKLIN, Primary Examiner. H. F. ROSS, Assistant Examiner.

Claims

1. IN A BLINDSTITCH SEWING MACHINE, WORK FEEDING MEANS, AN OSCILLATORY CURVED NEDDLE, COMPLEMENTARY STITCH FORMING MEANS COOPERATING WITH SAID NEEDLE TO FORM A LINE OF STITCHING, A SHIFTABLE NODE FORMER ADAPTED TO COOPERATE WITH THE WORK TO FORM A BODE THEREIN IN THE PATH OF SAID NEDDLE, A MAIN DRIVE SHAFT, AND CONNECTIONS FROM SAID DRIVE SHAFT FOR OPERATING SAID WORK FEEDING MEANS, SAID NEDDLE, SAID COMPLEMENTARY STITCH FORMING MEANS AND SAID NODE FORMER, SAID CONNECTIONS FOR OPERATING SAID NODE FORMER COMPRISING A DWELL CAM HAVING A SEMI-CYLINDRICAL SURFACE AND BEING ADAPTED TO SHIFT THE NODE FORMER INTO AND OUT OF ITS ACTIVE NODE FORMING POSITION, SAID LAST MENTIONED CONNECTIONS BEING SO CONSTRUCTED AND ARRANGED THAT SAID SEMI-CYLINDRICAL SURFACE RETAINS SAID NODE FORMER IN ITS FULLY ACTIVE POSITION THROUGHOUT THE TIME THAT THE NEEDLE IS ENGAGED WITH THE WORK.