US2950695A - Looper drive for double chain stitch sewing machines - Google Patents

Description

g- 1960 c. .1. M. BENINK ETAL 2,950 695 LOOPEER DRIVE FOR DOUBLE CHAIN STITCH SEWING MACHINES Filed Nov. 1, 1957 v 4 Sheets-Sheet 2 INVENTORS Chfishaan 30805 Marinas BEN/Mk Waller IRMSCHER WING MACHINES Aug. 30, 1960 C. J. M. BENlNK ETAL LOOPER DRIVE FOR DOUBLE CHAIN STITCH SE Filed NOV. 1, 1957 4 Sheets-Sheet 5 [WV E N Tom; Chrisiv'aan Mar/nus 35 w mp IEMSL'HER A gE/Vf.

Fliwwiii Aug- 1 c. J. M. BENINK ETAL 2,950,695

LOOPEIR DRIVE FOR nousu-z CHAIN STITCH SEWING MACHINES Filed Nov. 1, 1957 4 Sheets-Sheet 4 Fig. 7

Patented Aug. 30, 1960 LOOPER DRIVE FOR DOUBLE CHAIN STITCH SEWING MACHINES Christiaan Joseph Marinus Benink and Walter Irmscher, both of Kaiserslautern, Pfalz, Germany, assignors to G. M. Pfatf A.G., Kaiserslautern, Pfalz, Germany Filed Nov. 1, 1957, Ser. No. 693,994 Claims priority, application Germany Nov; 2, 1956 4 Claims. (Cl. 112-200) The invention relates to the drive means for the looper of double chain stitch sewing machines of the type equipped with needle and base feeding means generally referred to as compound feed.

/ Double chain stitch sewing machines which sew in downward direction of the arm as well as double stitch fiat sewing machines with needle feeding means are already known in which the looper moves in'the direction of sewing. In machines of this type the loop gripping and discarding motion of the looper is constant. When the stitch length is changed, the conditions of stitch formation change likewise. With loopers which operate in the direction of sewing it is also necessary to assist the looper during stitch formation by means of a thread spreading device.

For the sake of dispensing with the usually complicated spreading device it has already been proposed for a double chain stitch fiat sewing machine to make the looper operate perpendicularly to the direction of sewing and to relate the needle evading movement cf the looper which occurs in the direction of sewing to the feeding operation. Thus, in sewing machines of this type the needle evading movement is also changed proportionately as the stitch length is changed.

However, this is not satisfactory. Thus, for example, if the needle evading movement is arranged for a medium stitch length, then this movement also becomes very small or very large when a very small or large stitch length is set up. Adjusting to stitch length zero results in no stitch formation at all because the looper no longer executes a needle evading movement. Therefore, in order to adapt the needle evading movement to the different stitch lengths several adjusting possibilities are provided in the known machines.

It is an object of the present invention to eliminate the disadvantages of the known types of machines which operate in accordance with different basic principles by using'the simplest possible means.

In accordance with the invention the movement of the loopers in the direction of sewing is composed of a constant movement and a variable movement superimposed thereon which depends on the advancing movement of the needles. Thus in machines having loopers operating in the direction of sewing the loop catching and discarding movements and in machines having loopers op erating perpendicularly to the direction of sewing the needle evading movement is composed of a constant and a variable movement.

In machines where the transfer of the movement to the loopers or to the material feeding means takes place from the shaft of the drive mechanism by way of traction rods and rocker cranks this can be materialized in particularly simple fashion in that the rocking crank for the constant looper movement in the direction of sewing is journalled in arms of the rocking crank for the advancing movement of the material.

Further objects of the invention and details as to the advantages obtained thereby will become apparent flom the following description of the embodiment of the new looper drive illustrated in the accompanying drawings wherein:

Fig. 1 is a perspective view of a double chain stitch sewing machine adapted for feeding in arm downward direction with catcher operating perpendicularly to the direction of sewing, provided with the catch drive in accordance with the invention;

Fig. 2 is a front view of the machine, partly in section;

Fig. 3 is a section taken along line III-III in Fig. 2;

Fig. 4 is a plan view of the carrier arm with the cover plate removed;

Fig. 5 is a top view of the bridge and of the adjustable cams;

Fig. 6 is a sectional view of one of the cam members and its adjusting member taken substantially along line VI-Vl in Fig. 5 with the cam rotated through a 90 angle, and

Fig. 7 is a sectional view taken along line VIIVII in Fig. 6.

The standard 1 of the machine housing has an overhanging arm 2 into which merges a forwardly extending head 3 at one end while a downwardly extending arm 4 is joined to the other end. The lower end of arm 4 merges into a horizontal carrier arm 5, the free end of which ends up below head 3.

The main drive shaft 6 is journalled in arm 2 which carries the drive pulley 7 at the front end. The spring biased presser foot bar 8 with the presser foot 9 and the reciprocating needle bar 10 which oscillates in the direction of the carrier arm 5 and which carries two needles 11 is provided in the head 3 in the usual manner.

The operation of the needle bar 10 is effected in a known manner from the drive shaft 6 by way of a crank for the reciprocating movement and an adjustable cam 12 for the to-and-fro oscillations. The cam 12 is provided with a setting member 13 having a stopping groove 14 adapted to be engaged by a detent 16 secured to one end of a yoke 15. The adjustable cam 12 is operatively connected by way of a cam arm 17, a double armed oscillator lever 18 and a draw bar 19 to the needle bar oscillator.

The material feed dog 20 is mounted at the forward end of the carrier arm 5 being secured to the material feed bar 22 by means of screws 21. This bar is journalled by means of a bolt 23 upon a double rocker arm 24 which is pivotally movable about a pivot axis 25 secured to the carrier arm 5 and to which also one end of a link 26 is secured, the other end of which is linked to rockable crank 23 (see also Fig. 3). The latter is journalled on an axle 29 which is disposed transversely of the arm 4 and is secured against displacement by screws 30. The central position of the rockable crank 28 is secured by means of two set collars 31 and 32. Another arm 33 having a ball shaped end is provided on crank 28 to which a connecting rod 34 is connected which at its other end encompasses an adjustable cam 35 provided upon the drive shaft 6. Cam element 35 is provided with an adjusting member 36 having a detent or stopping groove 37 which is engageable by a detent 38 provided on the other end of the bridge 15.

The cams 12 and 35 with their respective adjusting members 13 and 36 are of the well known type disclosed in Us. Patents 2,128,031, 2,161,579 and 2,491,449, as well as in German Patent 866,444, which illustrate different embodiments of such adjustable cams.

The cam mechanisms employed in applicants machine operate in accordance with the same principle, only one of them being illustrated in Figs. 6 and 7. The setting or adjusting member 13 comprises a base plate 72 which 'portion 43. spring 44 (Fig. 2), which restrains the detents 16 and 33 is secured by means of a screw 73 to arm shaft 6. A setting disc 74 rotatable relative to shaft 6 and the cam support 75 are mounted on shaft 6 adjacent to the plate 72. 'A pair of collar, screws 76extend through members 72, 74 and 75 and are supported against base plate72 by nuts 77 while being slidable in arcuate slots 78 provided in disc 74 and in straight slots 79 of. the cam support 75. Thus, setting disc 74 is rotatable relative to shaft 6 through an angle corresponding to the length of slots 78, while the cam support 75 may be moved perpendicularly in slots 79 without rotary movement relative to shaft 6. V

Shifting of the cam support 75 transversely of the arm shaft 6 is effected by relative ,movement between the'setting disc 74 and base plate 72 in that a pin 89 secured in the cam suPPDrt 75 is guided in an arcuate slot 81 of the disc 74. A' ratchet bolt 83 which engages ratchet teeth 84 in disc 74, and is biased by spring 82 to retain disc 74, yieldingly, protects said disc '74 and thereby said cam support 175 against unintentional rotation.- The shifting is effected in that the detent 16 is caused to engage the notch orv groove 14 to hold the setting disc 74, while shaft 6 and with it the base plate 72 and cam support 75 are rotated against the action of the spring biased means 82, 83, 84 so that the setting of the eccentricity of cam 12 is elfected by way of the pin and slot guiding means 80, '81. The extent of the eccentricity adjustment is reflected by the movements of the machine elements thereby affected, such as the needle bar 10.

A rearwardly extending arm 39 (Fig. 5) is provided on bridge '15 which is rotatably secured by means of a collar screw 49 to a support 41 which latter is provided by means of screws 42 upon the flattened center hearing The bridge 15 is biased by means of'a depends on themagnitude of the feeding movement, and this is achieved by the journalling of the rocker crank 65 in the arms 27 of the rockable crank 28.

For operation the spring biased push button 47 is pressed against bridge 15 and'lowers the same against the pressure of spring 44 until the detents 16 and 38 contact the setting members 13 and 36. While maintaining the finger pressure on button 47 the drive shaft 6 is turned until the detents 16 and 38 are seated in the grooves 14 and 37. The magnitude'of the continuing rotation of the drive shaft .6 determines the magnitude of the change in the stitch length. Upon termination of the adjusting procedure the pressure on button 47 is released so that the button and the bridge return to their positions of rest under the pressure of the corresponding springs.

Having now described our invention with reference to the embodiment thereof illustrated in the drawings, ,we do not wish to be limited thereto, but what we desire to protect by Letters Patent of the United States is set forth in the appended claims. a

We claim: a r

1. Looper and feed mechanism for a double chain stitch sewing machine having a housing including a machine arm, a main drive shaft supported in said arm and compound feeding means comprising a needle bar, a first reciprocable member and a needle bar oscillator supporting said needle bar for swinging movement and opcratively connected to said reciproeable member; first adjustable cam means mounted on said drive shaft and connected to said first reciprocable member for imparting swinging movement to said needle bar oscillator, a feed bar, a feed dog supported endwise of said feed ba r befrom engaging the grooves 14 and 37 of the cams 12 and 35. The spring 44 is supported on the other hand 7 upon the bearing member 43 and is secured by a pin 45.

A spring biased push button 47 provided in the cover 46 of the machine arm above and centrally of bridge 15 is operative to simultaneously set the two cams 12 and 35. This insures that the needles 11 and the material feed dog 20 operate in synchronism.

' The raising and lowering movements of the material feed dog 20 are de rivedby means of a cam 48 from main drive shaft 6 and are transmitted by way of a double armed lever 54 journalled centrally on a pin 51, which is journalled in the carrier arm 5, and by way of a double link 52 to the forward part of the material feed bar 22.

A pair of thread carrying loopers 53 which cooperate with the needles 11 and move transversely of the direc tion of feed are secured to the forward end of a looper shaft 57 which is arranged in sleeve bearings 54, 55 and 56 for axial and pivotal movement. A crank 58 is clamped to the rear end of the looper'shaft 57 which is linked for operation by way of a pull rod 59 to a crank 60 secured to the end of the drive shaft 6. In this Inwner loop catching and casting movements are imparted to the loopers 53 in a direction transversely of the direction of sewing.

A pair of claws 61 are secured to the looper shaft 57 (Figs. 2 and 3) for the needle evading motions of the loopers 53 between which a slide block 63 is received which is journalled on a bolt 52. This bolt 62, is secured to the end of an arm 64 of an angmlar rocker crank 65 by means of a screw 66. The rocker crank 65 is secured in the arms 27 of the crank 28 upon an axle 67 fastened in place by screws 68 and is connected at its other arm 6? (Fig. 2) by means of cam connecting rod 70 to a cam 71 provided upon the drive shaft 6. The looper shaft 57 is thus subjected to a constant needle evading motion derived from cam 71 and a motion which low said needle bar and a looper shaft extending generally parallel to said drive shaft and supporting a looper below said feed dog; a second reciprocablemember operatively connected to said looper shaft, a first connecting rod and a cam on said drive shaft for'imparting constant reciprocating movement to said looper shaft; a rockable member supported in said housing having one arm operatively connected to said feed bar and 'pivotally supporting said second reciprocable member, second ad justable cam means mounted on said drive shaft and means including a second connecting rod having one end operatively connected to said second adjustable cam means and another end operatively connected to the other arm. of said rockable member for imparting reciprocating motion to said feed bar and for superimposing reciprocating movement on said looper shaft by way of said second reciprocable member; and rocking means on said looper shaft and onsaid drive shaft connected to impart rocking movement to said looper shaft.

2. Looper and feed mechanism for a den le chain stitch sewing machine having a housing including a machine arm, a main drive shaft supported in said arm and compound feeding means comprising a needle bar, a first reciprocable member and a needle bar oscillator supporting said needle bar for swinging movement and operatively connected to said reciprocable member; first adjustable cam means mounted on said drive shaft and connected to said first reciprocable member for imparting swinging movement to said needle bar oscillator, a feed bar, a feed dog supported endwise of said feed bar below said needle bar and a looper shaft extending generally parallel to said drive shaft and. supporting a looper below said feed dog; a second reciprocable member openatively connected to said looper shaft, a first connecting rod and a cam on said drive shaft for imparting constant reciprocating movement to said looper. shaft; a rockable member supported in said housing having one arm operatively connected to said feed bar and pivotally supporting said second reciprocable member, second adjustable cam means mounted on said drive shaft and means including a second connecting rod having one end operatively connected to said second adjustable cam means and another end operatively connected to the other arm of said rockable member for imparting reciprocating motion to said feed bar and for superimposing reciprocating movement on said looper shaft by way of said second reciprocable member; and rocking means on said looper shaft and on said drive shaft connected to impart rocking movement to said looper shaft, each of said first and said second adjustable cam means including a cam setting disk having a detent portion and a member in operative engagement with a cooperating portion of the cam associated therewith adapted to move said cam relative to said shaft in response to rotation of said shaft and means adapted to engage said first and second adjustable cam means operative to maintain the position of sid disks relative to each other.

3. Looper and feed mechanism for a double chain stitch sewing machine having a housing including a machine arm, a main drive shaft supported in said arm and compound feeding means comprising a needle bar, a first reciprocable member and a needle bar oscillator supporting said needle bar for swinging movement and operatively connected to said reciprocable member; first adjustable cam means mounted on said drive shaft and connected to said first reciprocable member for imparting swinging movement to said needle i-bar oscillator, a feed bar, a feed dog supported endwise of said feed bar below said needle bar and a looper shaft extending generally parallel to said drive shaft and supporting a looper below said feed dog; a second reciprocable member operatively connected to said looper shaft, a first connecting rod and a cam on said drive shaft for imparting constant reciprocating movement to said looper shaft; 21 rockable member supported in said housing having one arm operatively connected to said feed bar and pivotally supporting said second reciprocable member, second adjustable cam means mounted on said drive shaft and means including a second connecting rod having one end operatively connected to said second adjustable cam means and another end operatively connected to the other arm of said rockable member for imparting reciprocating motion to said feed bar and for superimposing reciprocating movement on said looper shaft by way of said second reciprocable member; and rocking means on said looper shaft and on said drive shaft connected to impart rocking movement to said looper shaft, each of said first and said second adjustable cam means including -a cam setting disk having a detent portion and a member in operative engagement with the cam associated therewith adapted to move said cam relative to said shaft in response to rotation of said shaft and means adapted to engage said first and second adjustable cam means operative to maintain the position of said disks relative to each other, said means comprising a yoke having a detent for each said disk adapted to engage the corresponding detent portion in the associated disk.

4. In a sewing machine having a housing supporting a drive shaft and provided with compound feeding means comprising a needle bar, a needle bar oscillator reciprocably supporting said needle bar, a feed bar, a feed dog supported endwise of said feed bar below said needle bar and a looper shaft extending generally parallel to said drive shaft and supporting a looper below said feed dog, reciprocable means having one end operatively connected to said drive shaft and another end connected to said looper shaft for imparting constant reciprocating movement to said looper shaft, and rockable means pivotally supported in said housing having one end opertively linked to said drive shaft and another end presenting a movable pivot connected to said feed bar adapted to impart reciprocating motion to said feed dog, said reciprocable means being pivotally supported intermediate its said one end and said other other end on said movable pivot in a manner to snperimpose the movements of said rockable means on said constant movement of said looper shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,419,462 Maier June 13, 1922 2,282,047 Graesser May 5, 1942 FOREIGN PATENTS 474,710 Germany Apr. 11, 1929 500,869 Germany June 25, 1930 866,444 Germany Feb. 9, 1953 72,915 Norway July 3, 1950

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