CA1099993A - Looper drive mechanism for sewing machines - Google Patents
Looper drive mechanism for sewing machinesInfo
- Publication number
- CA1099993A CA1099993A CA319,682A CA319682A CA1099993A CA 1099993 A CA1099993 A CA 1099993A CA 319682 A CA319682 A CA 319682A CA 1099993 A CA1099993 A CA 1099993A
- Authority
- CA
- Canada
- Prior art keywords
- looper
- motion
- crankpin
- drive means
- drive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- D—TEXTILES; PAPER
- D05—SEWING; EMBROIDERING; TUFTING
- D05B—SEWING
- D05B57/00—Loop takers, e.g. loopers
- D05B57/02—Loop takers, e.g. loopers for chain-stitch sewing machines, e.g. oscillating
Abstract
LOOPER DRIVE MECHANISM FOR SEWING MACHINES
ABSTRACT OF THE DISCLOSURE
A looper drive mechanism for sewing machines wherein rotational and axial movements are imparted to the looper by a motion transfer assembly driven off an oblique crank formed at one end of a rotating shaft. An operator controlled member is operatively connected to a mechanism which changes the relative working association between the oblique crank and motion transfer assembly so as to vary the looper avoid motion.
ABSTRACT OF THE DISCLOSURE
A looper drive mechanism for sewing machines wherein rotational and axial movements are imparted to the looper by a motion transfer assembly driven off an oblique crank formed at one end of a rotating shaft. An operator controlled member is operatively connected to a mechanism which changes the relative working association between the oblique crank and motion transfer assembly so as to vary the looper avoid motion.
Description
99~3 BACKGROUND OF IHE IN-vENrrI-oN
This invention relates generally to sewing machines - and more particularly -to a looper mechanism of the type in ; which both the lateral and swinging movements are derived from an oblique crank.
There are many variations of looper drive mechanisms which have been developed over the years. Looper mechanisms employing an oblique crank on the end of a shaft for imparting elliptical movements to the looper are, generally speaking, known in the art. Further to the above, it is desirable to have inherent in a looper drive mechanism -the capability of adjusting the looper avoid motion for various purposes, i.e., to compensate for various type loopers and -to add -to the versatility of the machine. In this regard, there is discLosed in U.S. Patent 2,998,787 granted September 5, 1961 to K. Pollmeier, a looper mechanism having an oblique crank adapted to impart elliptical motion to a looper including means for adjusting the sidewise or looper avoid motion.
However, a primary drawback with this prior looper drive mechanisms lies in the fact that adjustment of the sidewise motion of the looper requires that the pivot point for the looper be altered relative the reciprocal path of the needle.
It should be appreciated, however, that in the design of any looper drive mechanism it is very important to consider the thread manipulating implement, that is, the looper which is the ob]ect of the motion of the drive mechanism. The intri-cacies of the looper itself, that is, the multipllcity of accurately disposed cuts and formations that are situated thereon in exacting detail so as to allow the looper to cooperate to the fullest extent possible with the other ' stitch forming instrumentali-ties of -the machine is an impor-tant consideration so as -to provide ul-timate efficiency in -the cooperation of the looper with -the needles. When the pivot point of the looper is al-tered, however, -the relationship between the exacting details on -the looper relative the path of the needle are also changed. Therefore, the altering of the pivot point of the looper relative -the needle path so as to allow for adjustment of the looper avoid may greatly affect the ultimate efficiency of the looper as well as affecting formation of the stitch.
Anothèr fac-tor deserving consideration with regards tc the design of looper mechanisms is their accessability to adjustmen-t of -the looper avoid motion. While the adjust-ability of the looper mechanism disclosed in U.S. Patent
This invention relates generally to sewing machines - and more particularly -to a looper mechanism of the type in ; which both the lateral and swinging movements are derived from an oblique crank.
There are many variations of looper drive mechanisms which have been developed over the years. Looper mechanisms employing an oblique crank on the end of a shaft for imparting elliptical movements to the looper are, generally speaking, known in the art. Further to the above, it is desirable to have inherent in a looper drive mechanism -the capability of adjusting the looper avoid motion for various purposes, i.e., to compensate for various type loopers and -to add -to the versatility of the machine. In this regard, there is discLosed in U.S. Patent 2,998,787 granted September 5, 1961 to K. Pollmeier, a looper mechanism having an oblique crank adapted to impart elliptical motion to a looper including means for adjusting the sidewise or looper avoid motion.
However, a primary drawback with this prior looper drive mechanisms lies in the fact that adjustment of the sidewise motion of the looper requires that the pivot point for the looper be altered relative the reciprocal path of the needle.
It should be appreciated, however, that in the design of any looper drive mechanism it is very important to consider the thread manipulating implement, that is, the looper which is the ob]ect of the motion of the drive mechanism. The intri-cacies of the looper itself, that is, the multipllcity of accurately disposed cuts and formations that are situated thereon in exacting detail so as to allow the looper to cooperate to the fullest extent possible with the other ' stitch forming instrumentali-ties of -the machine is an impor-tant consideration so as -to provide ul-timate efficiency in -the cooperation of the looper with -the needles. When the pivot point of the looper is al-tered, however, -the relationship between the exacting details on -the looper relative the path of the needle are also changed. Therefore, the altering of the pivot point of the looper relative -the needle path so as to allow for adjustment of the looper avoid may greatly affect the ultimate efficiency of the looper as well as affecting formation of the stitch.
Anothèr fac-tor deserving consideration with regards tc the design of looper mechanisms is their accessability to adjustmen-t of -the looper avoid motion. While the adjust-ability of the looper mechanism disclosed in U.S. Patent
2,998,787 is acccssible, it has the drawback of altering the pivot point of the looper relative the needles as discussed above. Other known looper mechanisms employing an oblique crank, and more particularly the looper mechanism shown in U.S. Paten-t 2,160,355 granted May 30, 1939 to A. H. De Voe require access to the interior of the machine to adjust the amplitude of looper avoid. That is, with the design disclosed in the latter patent it is necessary to reposition the oblique crankpin relative the driving shaft, thus necessltating access-to the interior of the machine. However, a further drawback with this design is that -the repositioning of the crankpin relative the rota-ting shaft can result in displacement of the looper blade relative -the needles. When u-tilized with multiple needle machine, as well may be the case with the present invention, the displacement of the looper blade relative the needles is ultimately importan-t. Therefore, ~99~3 . .
adjustment of the looper avoid motion as disclosed in United States Patent 2,160,355 not only has called for accessibility to the interior of the machine, thus resulting in down time, but such an adjustment further requires that the looper blade be repositioned relative the needles so as to allow the looper to effectively cooperate with the latter in the formation of a stitch.
As is apparent, the repositioning of the looper blade requires a certain degree of expertise, thus resulting in further down-time of the machine.
The present invention is intended to overcome all of the above mentioned difficulties by providing a modular looper mechanism which main-10 tains a constant pivot point for the looper regardless of the degree of looper avoid motion. In addition, the present invention allows adjustment of the amplitude of looper avoid without requiring access to the interior of the machine and does not require repositioning of the looper blade relative the needle when the avoid motion is changed as has been heretofore known.
SUMMARY OF THE INVENTION
In view of the above and in accordance with the present invention there is disclosed a modular looper drive mechanism which is provided with means enabling adjustment of the looper avoid motion.
The invention provides in a sewing machine having a frame~ stitch 20 forming instrumentalities including a reciprocal needle means, a looper and a looper drive mechanism that allows for modulation of the looper avoid move-ment comprising:
drive means for imparting motion to said looper including an oblique crankpin;
motion transfer means for pivotally and laterally supporting said looper;
means for interconnecting the motion transfer means and said crank-pin such that movement of said crankpin results in said looper being dis-placed in a generally elliptical path defined by the simultaneous pivotal and lateral movement of the looper;
means in operative engagement with the drive means for selectively shifting the position of said interconnecting means relative the longitudinal ~- -4-axis of the drive means whereby modulating the lateral movement imparted to said looper; and said motion transfer means being mounted so that a fixed relation-ship is maintained between -the pivot point for said looper and said stitch forming instrumentality when the lateral movement of the looper is modulated.
The motion transfer means in the embodiment described herein is axially and rotatably mounted in the frame of the machine by two fixed bear-ings whereby the location of the looper pivot point and disposition of the looper blade relative the needles is maintained constant regardless of the degree of looper avoid motion. During operation of the machine, as the drive shaft rotates, the gyratory movements of the oblique crank imparts to the looper carrier, through the motion transfer assembly, the required rotational and axial motions whereby giving the looper its loop seizing and sideways motions.
When it is desirous to change the amplitude of the looper avoid motion, it is quickly and easily adjusted by the operator from outside the frame, thus eliminating the need for admittance to the workings of the machine. Therefore, the amount of downtime or time during which the machine is not operating, is kept at a minimum. Adjustment of the looper avoid motion is achieved by providing an eccentric member assembly, selectively operable by the operator to slideably move the modular drive assembly and more particularly the crankpin within the frame. Movement of the crankpin causes displacement of the motion transfer assembly along an axis transverse to the axis of the drive assembly thus shifting the location of the connection between the crankpin 9~93 and the motion transfer assembly relative the axis of the rotating shaft. Since the distance between the connection and the axis of the rotating shaft is determinative of the degree of sidewise motion of the looper, with the design and arrangement of the type hereinafter described, it is possible to adjust the looper avoid motion but yet maintain a common pi~vot point and a predetermined path of travel for the looper. In this manner the exacting details of the looper are used to their fullest potential with regard to handling of the threads and formation of the stitcho The disclosed modular looper drive mechanism is compact and requires a minimum number of operating parts to provide the necessary elliptical motion to the looper. Moreover, the parts therefor~are exchangeable quickly and without trouble.
The modular mechanism is adjustable and yet maintains a constant pivot point for the looper. The looper avoid motion can be selec-tively adjusted by the operator from a point remote from the stitch forming area of the machine~ to meet various conditions of operationO Thus~ the modular looper drive mechanism permits quick and easy adjustment of the looper avoid motion without the need of access to the interior of the machine.
BRIEF DESCRIPTION OF THE DRA~INGS
~ith the above and other objects in view that will hereinafter appear, the nature of the invention will be more ag91~t3 clearly understood by reference to the following detailed description, the appended claims, and the several views illustrated in the accompanying drawings, in which:
FIG. l is a front elevational view of a presently preferred embodiment for a looper drive mechanism;
FIG. 2 is a sectional plan view of the looper drive mechanism -taken along line 2-2 of FIG. 1, FIG. 3 is an enlarged secti.onal view of a portion of FIG. 2 showing the details of the modular looper drive 10 assembly.
FIG. 4 is a fragmentary sectional side view of the : looper drive mechanism.
FIG. 5 is an enlarged front sectional view taken along line 5-5 of FIG. 4.
FIG. 6 .is a disassembled perspective view of a portion of the looper drive mechanism.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in more detail to the drawings, in which like reference numerals indicate like parts throughout the several views, and more particularly to FIGS. 1 and 2 where it may be seen that most of the moving parts of the modular looper drive mechanism are located within the machine frame 10 of the sewing machine. The sewing machine shown in the drawings is provided with stitch forming instrumentality means 12 generally indicated in FIG. 1 by a needle which cooperates with a looper 14. The looper 14 must be moved across the path of needle reciprocation to seize and shed loops of thread from the needle and must also be shifted alternately sidewise to avoid the needle alternately on opposite sldes thereof. The four motion pa-th which the looper is required to execu-te is well known in the sewing machine art in machines for sewing chainstitches (Federal Stitch Type 401). A bed shaft 16 is ~ournaled in the frame 10 and serves to impart the required motion to the looper 14 and stitch forming instrumentality means 12 in timed relation.
As may be appreciated, the showing of the machine here is greatly simplified and only certain key parts will be specif-ically reEerred to inasmuch as reference oE specific details is well known in the art.
The frame 10 is provided with a bore 18 which has - slideably mounted therein a modular looper drive assembly 20. The looper drive assembly includes a -tubular housing or casing 22 which is provided with bearing assembly means 24 and 26, and a stub shaft 28. Both the stub shaft 28 and the bed shaft 16 have secured thereon sprocket wheels 30 and 32, respectively, which are connected by a timing belt 33. The stub shaft 28 has a crankpin 34 formed at one end thereof, the longitudinal axis of which is inclined to the axis of shaft means 28. Upon rotation of the shaft 28 the path traced by the longitudinal axis of the oblique crankpin 34 defines a cone having its vertex on the longitudinal axis of the shaft 28.
As best seen in FIG. 3, the s-tub shaft 28 is provided with a shaft head 36 (FIG. 2 and 6) having a step portion 38 which is greater in diameter than is shaft 28.
For a portion of its length opposite the heacl 36, the shaEt 28 is threadably engaged with a retainer nut 'lO. Tele-scopically arranged on retainer nut 40 and threadably engaged with the tubular casing 22 is a bearing retainer nut 42 which is further provided wi-th an oil seal 44 whereby prevent-ing lubrican-t from leaking from the drive assembly 20.
Positioned intermediate the step portion 38 and the retainer nut 40 are the bearing assembly means 24 and 26 which in the preferred embodiment are angular contact bearings. The inner races 46 and 48 of bearing means 24 and 26 are in contact with re-tainer nut 40 and the step portion 38, respec~
; tively. The ou-ter race 50 of bearing means 24 is forced into engagement with a step 52 in housing 22 when the bearing retainer nut 42 is tlghtened into the housing 22 whereby preventing axial displacement of bearing means 24. The outer race 54 of bearing means 26 is biased to the lef-t, as viewed in FIG. 3, under the influence of a compression spring means 56. The pressure of the spring tends to keep the races of the bearings in contact with the balls 57. As one skilled in the art may appreciate the vectorial direction of the force directed against the bearing means 26 by spring means 56 is important to note in view of the vectorial direction of the forces inherent with the looper mechanism.
With an arrangement such as described above, it is possible to preload the looper drive assembly by tightening the retainer nut 40 which, in turn, causes compression of spring means 56. The compression of spring means 56 results in oppositely and outwardly directed forces or axial thrusts being applied on each of the bearing means which, in view of their angular contact, prevent axial displacement of the shaft 28 relative the housing 22. By preventing axial displacement of shaft 28 relative the housing 22 a consistent looper path may be assured. In addition, the preloading of the looper drive assembly greatly reduces the impact forces, and therefore noise, associated with the assembly.
From the above, it should be noted t.hat by the presen-t invention the looper drive assembly 20 can be assembled outside of the constraints of the machine and then inser-ted into the bore 18 as a modular uni-t. The housing 22 is secured against rota-tion by an adjustable eccentric assembly 110 which forms a par-t of this inven-tion and will be described in greater detail hereinbelow.
Arranged in an operative working association with the looper drive assembly 20 and more particularly with the crank arm 34 is a mechanism or motion transfer assembly 60.
The motion transfer assembly 60 is moveably mounted in the machine frame about a fixed axis which extends -transverse and generally perpendicular to the longitudinal axis of the stub shaft 28. The mo-tion transfer assembly 60 includes an apertured cylindrical slide 62, a pivot pin 64 and a rock frame 66. As with the modular looper drive assembly 20, the motion transfer assembly 60 may be assembled outside the constraints of the machine and then inserted into an operative working association with the crankarm 34 through a bore 68 in the frame 10. In its assembled position, the crankarm 34 is operatively connected to the force transfer assembly by means of the pivot pin 64.
Referring now to FIGS. 2 and 6, the cylindrical slide 62 is formed with axially aligned spaced arms 72 and 74 in which is journaled the crankpin 34 and so as to lessen the frictional forces inherent between the slide 62 and crankpin 34 bearing assemblies 77 and 79 are inserted there-between. The pivot pin 64 is fixed within the cylindrical slide at a perpendicular angle thereto by the crankpin 34 which passes through an aperture 80 in the pin 64. The rock frame 66 is essentially a box shaped element having two oppositely aligned apertures 76 and 78 which serve as bearing journals for the ends of the pivot pin 64. Thus, in the assembled position as shown in Figure 2 and 4 a connection is established at 70 between the crankpin 34 and the motion transfer assembly 60. It is, therefore, clear that the gyratory or cone~like path of the crankpin 34 will cause the rock frame 66 to simultaneously move in a rotational and translational direction.
i The rock frame 66 is provided with a short bearing journal 81 extending outwardly from one side of the frame and a long bearing journal 82 extending coaxially out from the other side. The bearing journal 81 is mounted for axial and rotary movcment in a bearing block 84 adapted to be securely held in the machine frame 10. The other bearing journal 82 is similarly mounted in another bearing block 86 which is adapted to be securely held by an end cover 88.
The bearing block 86 is provided with a sealing means 90 which prevents machine lubricant from leaking around the journal 82. The end cover 88 is secured to the frame 10 by any suitable means such as 92 and serves to seal the bore 68 through which the motion transfer assembly 60 is inserted into its working position as shown in Figure 20 It should, therefore, be clear that movement of the motion transfer assembly 60 is constrained to movement about and along its longitudinal axis. Accordingly, the pivot point of the looper, generally indicated in Figure 1 by reference numeral 94 is constant, or fixed that is~ it will remain the same regard-less of the degree of sidewise motion imparted to the looper 14.
The bearing journal 82 ex-tends beyond the frame 10 and has removably secured at i-ts distal end a looper carrier 96. The looper carrier 96 is clamped on -the journal 82 by any suitable means such as screw 98. The distal end of the 5 journal 82 is provided with notches 100 and 102. In opera-tive association with the no-tches 100 and 102 are adjustment means 104 and 106, respec-tively, which are threadably engaged with the carrier 96. After the clamp screw 98 is loosened, the operator can adjust the looper 14 relative the sewing instrumentality 12 with minute detail by correspondingly tightening and loosening the adjustment means 104 and 106 until the proper setting is achieved. Once the operator has attained the ultimate efficiency setting of the looper relative the sti-tch forming instrumentality, the clamp screw 98 may be tightened whereby fixing the position of the looper carrier 96 with respect to the journal 82.
With the present arrangement, and as mentioned above, the looper drive assembly 20 and the mechanism means 60 are connected at 70. It should be appreciated that the working position or location of the pivot pin 64 rela-tive to the longitudinal axis of shaft 28 is de-terminative of the degree of looper avoid motion. In this rega~d, and so as to add to the versatility of the machine, one of the novel and unique-features of the present invention is the provision of an adjustable assembly means 110 which is adapted to adjust the position of the pivotal connection 70 along the longitu-dinal axis of motion transfer assembly 60 and relative the axis of shaft 28 whereby varying the amplitude of sidewise motion impartecl to the looper 14.
The adjustable eccentric is formed by an assernbly of an inner member 112 adap-ted to prevent ro-tation of -the housing 22 and an outer apertured flange or locking member 114. The member 112 is journalecl for rotation in the frame 10 at a point remote from the stitch forming instrumentality and is provided at one end with an eccentric stud or cam 116 which is adapted to be embraced by a recess 118 formed in the outer periphery of casing 22. The other extremity of member 112 has a step portion 120 formed with a tool accom-odating slot l22. The flange 114 is formed to telescopically fit over the step portion 120 and is adap-ted to secure or lock the member 112, and thereby the stud 116, in place once the flange 114 is securely fixed in posi-tion by any suitable means such as 124.
To facilitate adjustment of the eccentric unit 110 of this invention, the flange 114 has formed thereon, indicia such.as + or - 0,30 and 60 which are cooperative with the slot 122 on member 112 to denote different avoid motions which the looper might frequently require. The indicia 0, 30 and 60 for instance, may be choosen to denote an appropriate avoid motion to suit small, medium or large type needles or loopers. Of course, any number of settings more or less than those shown can be used and is within the scope of this invention.
OPERATION OF THE MACHINE .
In operation, when the operator desires to select a particular degree of looper avoid motion, he merely rotates member 112 until the slot 122 is aligned with the desired indicia on the flange 114 which is reflective of a preset '\
degree of looper avoid motion. Since the eccentric stud 116 is fast on member 112 it too is rotated therewith.
~ ovement imparted by stud 116 is transmitted through the housing 22 thus causing the modular looper d~ive assembly 20, and more particularly the crankpin 34, to assume a predetermined working relationship with the motion transfer assembly 60. With the present arra~gement, as the position of crankpin 34 is changed, the position of the motion transfer assembly 60 is changed~ thus varying the location of the point 70 relative to the longitudinal axis of shaft 28. When the longitudinal axes of crankpin 34, motion transfer assembly 60 and the shaft 28 intersect at a single point, the looper 14 merely has rotational motion, and substantially no sidewise motion is transmitted thereto.
However, when the intersection point 70 is displaced from its congruent relationship with the longitudinal axis of shaft 28 by moving the crankpin 34 an avoid motion will be imparted to the looper. It should be appreciated however, that during operation of the machine some degree of sidewise motion is always imparted to the looper 14 so as to avoid the needle.
me rotary motion of the shaft 28 and the gyratory or conelike motion of the crankpin is converted into combined rotary and axial movement by the motion transfer assembly 60. The looper 14 is thus given combined rotary and axial movement but the degree of sidewise motion is variable. The amplitude of sidewise motion imparted to the looper 14 is controlled by the location of the connection 70 relative the longitudinal axis of shaft 28 as established by the position of the adjustable eccentric assembly 110. ~ven though the _ 14 -dis-tance between the connection 70 and the axis of shaft 28 determines the degree of sidewise mo-tion imparted to the looper 14, an important poin-t to no-te is tha-t although the : looper avoid mo-tion is capable of adjustment, the axis or pivo-t point 94 for the looper 14 remains the same regardless of -the degree of looper avoid motion. In this manner, the ; looper 14 is employed to its fullest potential-in handling the thread and forming a stitch.
. Thus it is apparent -that there has been provided a 10 Looper Drive Mechanism for Sewing Machines which fully satisfies the objects, aims, and advantages set forth above.
While the invention has been described in conjunc-tion with specific embodiments thereof, it is evident that many al-ter-natives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description.
Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.
adjustment of the looper avoid motion as disclosed in United States Patent 2,160,355 not only has called for accessibility to the interior of the machine, thus resulting in down time, but such an adjustment further requires that the looper blade be repositioned relative the needles so as to allow the looper to effectively cooperate with the latter in the formation of a stitch.
As is apparent, the repositioning of the looper blade requires a certain degree of expertise, thus resulting in further down-time of the machine.
The present invention is intended to overcome all of the above mentioned difficulties by providing a modular looper mechanism which main-10 tains a constant pivot point for the looper regardless of the degree of looper avoid motion. In addition, the present invention allows adjustment of the amplitude of looper avoid without requiring access to the interior of the machine and does not require repositioning of the looper blade relative the needle when the avoid motion is changed as has been heretofore known.
SUMMARY OF THE INVENTION
In view of the above and in accordance with the present invention there is disclosed a modular looper drive mechanism which is provided with means enabling adjustment of the looper avoid motion.
The invention provides in a sewing machine having a frame~ stitch 20 forming instrumentalities including a reciprocal needle means, a looper and a looper drive mechanism that allows for modulation of the looper avoid move-ment comprising:
drive means for imparting motion to said looper including an oblique crankpin;
motion transfer means for pivotally and laterally supporting said looper;
means for interconnecting the motion transfer means and said crank-pin such that movement of said crankpin results in said looper being dis-placed in a generally elliptical path defined by the simultaneous pivotal and lateral movement of the looper;
means in operative engagement with the drive means for selectively shifting the position of said interconnecting means relative the longitudinal ~- -4-axis of the drive means whereby modulating the lateral movement imparted to said looper; and said motion transfer means being mounted so that a fixed relation-ship is maintained between -the pivot point for said looper and said stitch forming instrumentality when the lateral movement of the looper is modulated.
The motion transfer means in the embodiment described herein is axially and rotatably mounted in the frame of the machine by two fixed bear-ings whereby the location of the looper pivot point and disposition of the looper blade relative the needles is maintained constant regardless of the degree of looper avoid motion. During operation of the machine, as the drive shaft rotates, the gyratory movements of the oblique crank imparts to the looper carrier, through the motion transfer assembly, the required rotational and axial motions whereby giving the looper its loop seizing and sideways motions.
When it is desirous to change the amplitude of the looper avoid motion, it is quickly and easily adjusted by the operator from outside the frame, thus eliminating the need for admittance to the workings of the machine. Therefore, the amount of downtime or time during which the machine is not operating, is kept at a minimum. Adjustment of the looper avoid motion is achieved by providing an eccentric member assembly, selectively operable by the operator to slideably move the modular drive assembly and more particularly the crankpin within the frame. Movement of the crankpin causes displacement of the motion transfer assembly along an axis transverse to the axis of the drive assembly thus shifting the location of the connection between the crankpin 9~93 and the motion transfer assembly relative the axis of the rotating shaft. Since the distance between the connection and the axis of the rotating shaft is determinative of the degree of sidewise motion of the looper, with the design and arrangement of the type hereinafter described, it is possible to adjust the looper avoid motion but yet maintain a common pi~vot point and a predetermined path of travel for the looper. In this manner the exacting details of the looper are used to their fullest potential with regard to handling of the threads and formation of the stitcho The disclosed modular looper drive mechanism is compact and requires a minimum number of operating parts to provide the necessary elliptical motion to the looper. Moreover, the parts therefor~are exchangeable quickly and without trouble.
The modular mechanism is adjustable and yet maintains a constant pivot point for the looper. The looper avoid motion can be selec-tively adjusted by the operator from a point remote from the stitch forming area of the machine~ to meet various conditions of operationO Thus~ the modular looper drive mechanism permits quick and easy adjustment of the looper avoid motion without the need of access to the interior of the machine.
BRIEF DESCRIPTION OF THE DRA~INGS
~ith the above and other objects in view that will hereinafter appear, the nature of the invention will be more ag91~t3 clearly understood by reference to the following detailed description, the appended claims, and the several views illustrated in the accompanying drawings, in which:
FIG. l is a front elevational view of a presently preferred embodiment for a looper drive mechanism;
FIG. 2 is a sectional plan view of the looper drive mechanism -taken along line 2-2 of FIG. 1, FIG. 3 is an enlarged secti.onal view of a portion of FIG. 2 showing the details of the modular looper drive 10 assembly.
FIG. 4 is a fragmentary sectional side view of the : looper drive mechanism.
FIG. 5 is an enlarged front sectional view taken along line 5-5 of FIG. 4.
FIG. 6 .is a disassembled perspective view of a portion of the looper drive mechanism.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in more detail to the drawings, in which like reference numerals indicate like parts throughout the several views, and more particularly to FIGS. 1 and 2 where it may be seen that most of the moving parts of the modular looper drive mechanism are located within the machine frame 10 of the sewing machine. The sewing machine shown in the drawings is provided with stitch forming instrumentality means 12 generally indicated in FIG. 1 by a needle which cooperates with a looper 14. The looper 14 must be moved across the path of needle reciprocation to seize and shed loops of thread from the needle and must also be shifted alternately sidewise to avoid the needle alternately on opposite sldes thereof. The four motion pa-th which the looper is required to execu-te is well known in the sewing machine art in machines for sewing chainstitches (Federal Stitch Type 401). A bed shaft 16 is ~ournaled in the frame 10 and serves to impart the required motion to the looper 14 and stitch forming instrumentality means 12 in timed relation.
As may be appreciated, the showing of the machine here is greatly simplified and only certain key parts will be specif-ically reEerred to inasmuch as reference oE specific details is well known in the art.
The frame 10 is provided with a bore 18 which has - slideably mounted therein a modular looper drive assembly 20. The looper drive assembly includes a -tubular housing or casing 22 which is provided with bearing assembly means 24 and 26, and a stub shaft 28. Both the stub shaft 28 and the bed shaft 16 have secured thereon sprocket wheels 30 and 32, respectively, which are connected by a timing belt 33. The stub shaft 28 has a crankpin 34 formed at one end thereof, the longitudinal axis of which is inclined to the axis of shaft means 28. Upon rotation of the shaft 28 the path traced by the longitudinal axis of the oblique crankpin 34 defines a cone having its vertex on the longitudinal axis of the shaft 28.
As best seen in FIG. 3, the s-tub shaft 28 is provided with a shaft head 36 (FIG. 2 and 6) having a step portion 38 which is greater in diameter than is shaft 28.
For a portion of its length opposite the heacl 36, the shaEt 28 is threadably engaged with a retainer nut 'lO. Tele-scopically arranged on retainer nut 40 and threadably engaged with the tubular casing 22 is a bearing retainer nut 42 which is further provided wi-th an oil seal 44 whereby prevent-ing lubrican-t from leaking from the drive assembly 20.
Positioned intermediate the step portion 38 and the retainer nut 40 are the bearing assembly means 24 and 26 which in the preferred embodiment are angular contact bearings. The inner races 46 and 48 of bearing means 24 and 26 are in contact with re-tainer nut 40 and the step portion 38, respec~
; tively. The ou-ter race 50 of bearing means 24 is forced into engagement with a step 52 in housing 22 when the bearing retainer nut 42 is tlghtened into the housing 22 whereby preventing axial displacement of bearing means 24. The outer race 54 of bearing means 26 is biased to the lef-t, as viewed in FIG. 3, under the influence of a compression spring means 56. The pressure of the spring tends to keep the races of the bearings in contact with the balls 57. As one skilled in the art may appreciate the vectorial direction of the force directed against the bearing means 26 by spring means 56 is important to note in view of the vectorial direction of the forces inherent with the looper mechanism.
With an arrangement such as described above, it is possible to preload the looper drive assembly by tightening the retainer nut 40 which, in turn, causes compression of spring means 56. The compression of spring means 56 results in oppositely and outwardly directed forces or axial thrusts being applied on each of the bearing means which, in view of their angular contact, prevent axial displacement of the shaft 28 relative the housing 22. By preventing axial displacement of shaft 28 relative the housing 22 a consistent looper path may be assured. In addition, the preloading of the looper drive assembly greatly reduces the impact forces, and therefore noise, associated with the assembly.
From the above, it should be noted t.hat by the presen-t invention the looper drive assembly 20 can be assembled outside of the constraints of the machine and then inser-ted into the bore 18 as a modular uni-t. The housing 22 is secured against rota-tion by an adjustable eccentric assembly 110 which forms a par-t of this inven-tion and will be described in greater detail hereinbelow.
Arranged in an operative working association with the looper drive assembly 20 and more particularly with the crank arm 34 is a mechanism or motion transfer assembly 60.
The motion transfer assembly 60 is moveably mounted in the machine frame about a fixed axis which extends -transverse and generally perpendicular to the longitudinal axis of the stub shaft 28. The mo-tion transfer assembly 60 includes an apertured cylindrical slide 62, a pivot pin 64 and a rock frame 66. As with the modular looper drive assembly 20, the motion transfer assembly 60 may be assembled outside the constraints of the machine and then inserted into an operative working association with the crankarm 34 through a bore 68 in the frame 10. In its assembled position, the crankarm 34 is operatively connected to the force transfer assembly by means of the pivot pin 64.
Referring now to FIGS. 2 and 6, the cylindrical slide 62 is formed with axially aligned spaced arms 72 and 74 in which is journaled the crankpin 34 and so as to lessen the frictional forces inherent between the slide 62 and crankpin 34 bearing assemblies 77 and 79 are inserted there-between. The pivot pin 64 is fixed within the cylindrical slide at a perpendicular angle thereto by the crankpin 34 which passes through an aperture 80 in the pin 64. The rock frame 66 is essentially a box shaped element having two oppositely aligned apertures 76 and 78 which serve as bearing journals for the ends of the pivot pin 64. Thus, in the assembled position as shown in Figure 2 and 4 a connection is established at 70 between the crankpin 34 and the motion transfer assembly 60. It is, therefore, clear that the gyratory or cone~like path of the crankpin 34 will cause the rock frame 66 to simultaneously move in a rotational and translational direction.
i The rock frame 66 is provided with a short bearing journal 81 extending outwardly from one side of the frame and a long bearing journal 82 extending coaxially out from the other side. The bearing journal 81 is mounted for axial and rotary movcment in a bearing block 84 adapted to be securely held in the machine frame 10. The other bearing journal 82 is similarly mounted in another bearing block 86 which is adapted to be securely held by an end cover 88.
The bearing block 86 is provided with a sealing means 90 which prevents machine lubricant from leaking around the journal 82. The end cover 88 is secured to the frame 10 by any suitable means such as 92 and serves to seal the bore 68 through which the motion transfer assembly 60 is inserted into its working position as shown in Figure 20 It should, therefore, be clear that movement of the motion transfer assembly 60 is constrained to movement about and along its longitudinal axis. Accordingly, the pivot point of the looper, generally indicated in Figure 1 by reference numeral 94 is constant, or fixed that is~ it will remain the same regard-less of the degree of sidewise motion imparted to the looper 14.
The bearing journal 82 ex-tends beyond the frame 10 and has removably secured at i-ts distal end a looper carrier 96. The looper carrier 96 is clamped on -the journal 82 by any suitable means such as screw 98. The distal end of the 5 journal 82 is provided with notches 100 and 102. In opera-tive association with the no-tches 100 and 102 are adjustment means 104 and 106, respec-tively, which are threadably engaged with the carrier 96. After the clamp screw 98 is loosened, the operator can adjust the looper 14 relative the sewing instrumentality 12 with minute detail by correspondingly tightening and loosening the adjustment means 104 and 106 until the proper setting is achieved. Once the operator has attained the ultimate efficiency setting of the looper relative the sti-tch forming instrumentality, the clamp screw 98 may be tightened whereby fixing the position of the looper carrier 96 with respect to the journal 82.
With the present arrangement, and as mentioned above, the looper drive assembly 20 and the mechanism means 60 are connected at 70. It should be appreciated that the working position or location of the pivot pin 64 rela-tive to the longitudinal axis of shaft 28 is de-terminative of the degree of looper avoid motion. In this rega~d, and so as to add to the versatility of the machine, one of the novel and unique-features of the present invention is the provision of an adjustable assembly means 110 which is adapted to adjust the position of the pivotal connection 70 along the longitu-dinal axis of motion transfer assembly 60 and relative the axis of shaft 28 whereby varying the amplitude of sidewise motion impartecl to the looper 14.
The adjustable eccentric is formed by an assernbly of an inner member 112 adap-ted to prevent ro-tation of -the housing 22 and an outer apertured flange or locking member 114. The member 112 is journalecl for rotation in the frame 10 at a point remote from the stitch forming instrumentality and is provided at one end with an eccentric stud or cam 116 which is adapted to be embraced by a recess 118 formed in the outer periphery of casing 22. The other extremity of member 112 has a step portion 120 formed with a tool accom-odating slot l22. The flange 114 is formed to telescopically fit over the step portion 120 and is adap-ted to secure or lock the member 112, and thereby the stud 116, in place once the flange 114 is securely fixed in posi-tion by any suitable means such as 124.
To facilitate adjustment of the eccentric unit 110 of this invention, the flange 114 has formed thereon, indicia such.as + or - 0,30 and 60 which are cooperative with the slot 122 on member 112 to denote different avoid motions which the looper might frequently require. The indicia 0, 30 and 60 for instance, may be choosen to denote an appropriate avoid motion to suit small, medium or large type needles or loopers. Of course, any number of settings more or less than those shown can be used and is within the scope of this invention.
OPERATION OF THE MACHINE .
In operation, when the operator desires to select a particular degree of looper avoid motion, he merely rotates member 112 until the slot 122 is aligned with the desired indicia on the flange 114 which is reflective of a preset '\
degree of looper avoid motion. Since the eccentric stud 116 is fast on member 112 it too is rotated therewith.
~ ovement imparted by stud 116 is transmitted through the housing 22 thus causing the modular looper d~ive assembly 20, and more particularly the crankpin 34, to assume a predetermined working relationship with the motion transfer assembly 60. With the present arra~gement, as the position of crankpin 34 is changed, the position of the motion transfer assembly 60 is changed~ thus varying the location of the point 70 relative to the longitudinal axis of shaft 28. When the longitudinal axes of crankpin 34, motion transfer assembly 60 and the shaft 28 intersect at a single point, the looper 14 merely has rotational motion, and substantially no sidewise motion is transmitted thereto.
However, when the intersection point 70 is displaced from its congruent relationship with the longitudinal axis of shaft 28 by moving the crankpin 34 an avoid motion will be imparted to the looper. It should be appreciated however, that during operation of the machine some degree of sidewise motion is always imparted to the looper 14 so as to avoid the needle.
me rotary motion of the shaft 28 and the gyratory or conelike motion of the crankpin is converted into combined rotary and axial movement by the motion transfer assembly 60. The looper 14 is thus given combined rotary and axial movement but the degree of sidewise motion is variable. The amplitude of sidewise motion imparted to the looper 14 is controlled by the location of the connection 70 relative the longitudinal axis of shaft 28 as established by the position of the adjustable eccentric assembly 110. ~ven though the _ 14 -dis-tance between the connection 70 and the axis of shaft 28 determines the degree of sidewise mo-tion imparted to the looper 14, an important poin-t to no-te is tha-t although the : looper avoid mo-tion is capable of adjustment, the axis or pivo-t point 94 for the looper 14 remains the same regardless of -the degree of looper avoid motion. In this manner, the ; looper 14 is employed to its fullest potential-in handling the thread and forming a stitch.
. Thus it is apparent -that there has been provided a 10 Looper Drive Mechanism for Sewing Machines which fully satisfies the objects, aims, and advantages set forth above.
While the invention has been described in conjunc-tion with specific embodiments thereof, it is evident that many al-ter-natives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description.
Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a sewing machine having a frame, stitch forming instrumentali-ties including a reciprocal needle means, a looper and a looper drive mechanism that allows for modulation of the looper avoid movement comprising:
drive means for imparting motion to said looper including an oblique crankpin;
motion transfer means for pivotally and laterally supporting said looper;
means for interconnecting the motion transfer means and said crank-pin such that movement of said crankpin results in said looper being dis-placed in a generally elliptical path defined by the simultaneous pivotal and lateral movement of the looper;
means in operative engagement with the drive means for selectively shifting the position of said interconnecting means relative the longitudinal axis of the drive means whereby modulating the lateral movement imparted to said looper; and said motion transfer means being mounted so that a fixed relation-ship is maintained between the pivot point for said looper and said stitch forming instrumentality when the lateral movement of the looper is modulated.
drive means for imparting motion to said looper including an oblique crankpin;
motion transfer means for pivotally and laterally supporting said looper;
means for interconnecting the motion transfer means and said crank-pin such that movement of said crankpin results in said looper being dis-placed in a generally elliptical path defined by the simultaneous pivotal and lateral movement of the looper;
means in operative engagement with the drive means for selectively shifting the position of said interconnecting means relative the longitudinal axis of the drive means whereby modulating the lateral movement imparted to said looper; and said motion transfer means being mounted so that a fixed relation-ship is maintained between the pivot point for said looper and said stitch forming instrumentality when the lateral movement of the looper is modulated.
2. The invention according to claim 1 wherein said motion transfer means is mounted for cooperation with the drive means and is adapted to impart pivotal and slideable movement to the looper, said motion transfer means being mounted so that movement of the pivot point of said looper relative to the reciprocal path of said needle means is prevented; and wherein said means for selectively shifting comprises operator controlled means for selectively moving said crankpin a controlled amount whereby the connection between the drive means and the motion transfer means is shifted relative to the axis of said drive means thus varying the amplitude of the looper avoid motion of the looper.
3. The invention according to claim 1 or 2 wherein said motion trans-fer means includes a rock frame having at least two axially aligned spaced arm means, there being a pair of axially aligned bearing means fixedly secured in said frame for supporting said arm means on a fixed axis relative said frame.
4. The invention according to claim 1 wherein said means for selective-ly shifting comprises adjustable eccentric means in operative engagement with the drive means for selectively moving said crankpin a controlled amount whereby the connection between the drive means and the motion transfer means may be shifted so as to vary its distance from the longitudinal axis of said drive means and thus vary the amplitude of the looper avoid motion of the looper.
5. The invention of claim 4 wherein said motion transfer means comprises:
a first member means having an aperture through which said crankpin passes;
a second member means journaled for rotational and translational movement about a fixed axis and being formed with at least two axially aligned apertures; and a third member means mounted on said crankpin and journaled in said apertures for joining the first and second member means in an operative work-ing association with the crankpin.
a first member means having an aperture through which said crankpin passes;
a second member means journaled for rotational and translational movement about a fixed axis and being formed with at least two axially aligned apertures; and a third member means mounted on said crankpin and journaled in said apertures for joining the first and second member means in an operative work-ing association with the crankpin.
6. The invention of claim 4 wherein said drive means is slideably mounted in said frame, said drive means comprises:
a shaft having said crankpin formed at one end thereof;
a casing means slideably journaled in said frame on an axis general-ly perpendicular to the fixed pivotal axis of said motion transfer means;
means for rotatably supporting said shaft in the interior of said casing means; and means in operative association with said shaft and said rotatably supporting means for preventing said shaft from moving endwise in and relative to said casing means.
a shaft having said crankpin formed at one end thereof;
a casing means slideably journaled in said frame on an axis general-ly perpendicular to the fixed pivotal axis of said motion transfer means;
means for rotatably supporting said shaft in the interior of said casing means; and means in operative association with said shaft and said rotatably supporting means for preventing said shaft from moving endwise in and relative to said casing means.
7. The invention of claim 6 wherein said means for rotatably support-ing comprises a pair of angular contact bearing means.
8. The invention according to claim 1 wherein said drive means is a rotary drive means which drives said oblique crankpin in a movement which traces out a cone-like path having a vertex lying on the axis of said drive means;
said means for selectively shifting comprising operator controlled means in operative engagement with the drive means for selectively moving the vertex of said cone-like path relative said rotational axis whereby changing the amplitude of lateral movement imparted to the looper carrier.
said means for selectively shifting comprising operator controlled means in operative engagement with the drive means for selectively moving the vertex of said cone-like path relative said rotational axis whereby changing the amplitude of lateral movement imparted to the looper carrier.
9. The invention according to claim 8 wherein said operator controlled means comprises:
a rotatably mounted adjustable member means including operative means operably connected to said rotary drive means for selectively moving same when the adjustable member means is turned;
locking means movable into engagement with said adjustable member means for securing said operative means, and thereby said rotary drive means, in a selected position.
a rotatably mounted adjustable member means including operative means operably connected to said rotary drive means for selectively moving same when the adjustable member means is turned;
locking means movable into engagement with said adjustable member means for securing said operative means, and thereby said rotary drive means, in a selected position.
10. The invention according to claim 9 further including indicia carried on said locking means and cooperative marking carried on said adjust-able member means for denoting the degree of translational movement imparted to said looper.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US87706578A | 1978-02-13 | 1978-02-13 | |
| US877,065 | 1978-02-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1099993A true CA1099993A (en) | 1981-04-28 |
Family
ID=25369175
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA319,682A Expired CA1099993A (en) | 1978-02-13 | 1979-01-16 | Looper drive mechanism for sewing machines |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS54117265A (en) |
| CA (1) | CA1099993A (en) |
| DE (1) | DE2901582C2 (en) |
| FR (1) | FR2416968B1 (en) |
| GB (1) | GB2014623B (en) |
| IT (1) | IT1118340B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0314149Y2 (en) * | 1985-10-16 | 1991-03-29 | ||
| DE102019219814A1 (en) | 2019-12-17 | 2021-06-17 | Pfaff Industriesysteme Und Maschinen Gmbh | Stitch forming tool assembly for a sewing system and sewing system with such an assembly |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE126710C (en) * | ||||
| US1569912A (en) * | 1922-03-14 | 1926-01-19 | Singer Mfg Co | Sewing-machine looper mechanism |
| US2160355A (en) * | 1938-09-29 | 1939-05-30 | Singer Mfg Co | Looper mechanism for sewing machines |
| DE1079435B (en) * | 1958-07-02 | 1960-04-07 | Duerkoppwerke Ag | Gripper drive for chain stitch sewing machines |
| US2998787A (en) * | 1959-06-22 | 1961-09-05 | Duerkoppwerke | Loop taker mechanism for chainstitch sewing machines |
| DE1949523U (en) * | 1963-03-14 | 1966-11-10 | Kochs Adler Naehmaschinenwerke | LOOK DRIVE FOR A CHAIN SEWING MACHINE. |
| JPS4910760B1 (en) * | 1969-07-24 | 1974-03-12 |
-
1979
- 1979-01-16 CA CA319,682A patent/CA1099993A/en not_active Expired
- 1979-01-17 DE DE2901582A patent/DE2901582C2/en not_active Expired
- 1979-02-09 GB GB7904741A patent/GB2014623B/en not_active Expired
- 1979-02-09 FR FR7903366A patent/FR2416968B1/en not_active Expired
- 1979-02-12 IT IT67301/79A patent/IT1118340B/en active
- 1979-02-13 JP JP1538379A patent/JPS54117265A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2014623B (en) | 1982-07-21 |
| FR2416968B1 (en) | 1986-05-09 |
| FR2416968A1 (en) | 1979-09-07 |
| DE2901582C2 (en) | 1983-01-05 |
| IT1118340B (en) | 1986-02-24 |
| GB2014623A (en) | 1979-08-30 |
| IT7967301A0 (en) | 1979-02-12 |
| JPS54117265A (en) | 1979-09-12 |
| DE2901582A1 (en) | 1979-08-16 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |