Patent Grant
11434592
A single sewing machine can be used for sewing a variety of materials, such as fabrics, bag closures, and/or the like. The subset of sewing machines used in industrial settings to sew bag closures for produce bags, grain bags, pet or livestock food bags, and/or the like are generally configured for sewing through bag material, such as multi-ply paper, netting, and/or other bagging materials. Given the similarities in usage for industrial sewing machines, the mechanical workings of these sewing machines may be identical, with small user-adjustable features for accommodating differences between materials and needed stitch characteristics for closing different bag types.
The most notable difference in stitch characteristics between various bag closures is often the stitch length, which directly impacts the “tightness” of the closure and the speed at which the bags may be sewn closed. A shorter stitch length creates a tighter seal that prevents grains or other small-size particulate materials from seeping through the closure, while a longer stitch length decrease the amount of time needed to seal a bag (because fewer stitches are required for a given bag). A sewing machine of this type used in a packaging facility may be required to have a first production run for a type of material with one size of particulate, and then switch to a second production run for a type of material having a second size of particulate. Thus, for a packaging facility to run efficiently, the sewing machine stitch length is advantageously changed between production runs to provide the longest (and thus fastest) stitch length that does not allow excess particulate materials to seep through the stitch chain.
Because of this, a need exists for user-friendly mechanisms enabling precise and quick adjustments to sewing machines to change the created stitch length. Moreover, a need constantly exists for sewing machine stitch length adjustments having a wider range of possible stitch lengths that may be created by a single sewing machine.
Various embodiments are directed to a stitch length adjustment mechanism for a sewing machine that provides a holding-force against unintentional movement of the stitch length adjustment mechanism during adjustment. In certain embodiments, the stitch length adjustment mechanism comprises a multi-bar linkage configured to move a material feed dog, the multi-bar linkage having at least one bar having an adjustable effective length controllable by a rack-and-pinion adjustment mechanism and having a holding spring configured to impede unintentional movement of the pinion relative to the rack.
Moreover, certain embodiments are directed to a looper thread tension adjustment mechanism configured to accommodate varying stitch length adjustments to ensure that the looper thread retains an optimal tension during sewing machine movement, regardless of the stitch length selected by a user. The looper thread tension adjustment mechanism comprises an adjustable looper thread eyelet that may be moved to increase or decrease the overall looper thread path length and to prevent undesirable looper thread whipping that may be caused by low looper thread tension.
Certain embodiments are directed to a sewing machine looper thread mechanism comprising: a reciprocating looper arm configured to tie a locking stitch with a looper thread and a needling thread; and an adjustable take-up eyelet secured relative to an exterior surface of the sewing machine; wherein the adjustable take-up eyelet is configured to redirect a looper thread from a first thread direction extending from a looper thread source to a second thread direction extending to the reciprocating looper arm; and wherein the adjustable take-up eyelet is configured for movement to adjust the length of the looper thread path between the looper thread source and the reciprocating looper arm.
In certain embodiments, the looper thread path extends at least substantially linearly from the reciprocating looper arm to a distal end of the adjustable take-up eyelet, and wherein the adjustable take-up eyelet is configured for movement to adjust a linear distance between the distal end of the adjustable take-up eyelet and the reciprocating looper arm. Moreover, in certain embodiments the adjustable take-up eyelet comprises: an elongated planar medial portion having a face surface and defining a linear adjustment slot extending through the face surface, wherein the adjustment slot is configured to slide relative to one or more fasteners securing the adjustable sewing machine looper thread take-up eyelet relative to the sewing machine; an angled base portion on a base end of the elongated planar medial portion, wherein the angled base portion has a base guide hole extending therethrough, and the angled base portion is angled relative to the face surface; and a skew distal end portion on a distal end of the elongated planar medial portion, wherein the skew distal end portion has a distal guide hole extending therethrough, and the skew distal end portion is skewed about an axis at least substantially aligned with the length of the elongated planar medial portion. In certain embodiments, a linear portion of the looper thread path extends between the base guide hole and the distal guide hole. In various embodiments, the looper thread path turns between the linear portion of the looper thread path extending between the base guide hole and the distal guide hole to a second at least substantially linear portion extending between the distal guide hole and the reciprocating looper arm. Moreover, the adjustable take-up eyelet is movable in certain embodiments in a direction parallel with the linear portion of the looper thread path.
Various embodiments are directed to an adjustable sewing machine looper thread take-up eyelet comprising: an elongated planar medial portion having a face surface and defining a linear adjustment slot extending through the face surface, wherein the adjustment slot is configured to slide relative to one or more fasteners securing the adjustable sewing machine looper thread take-up eyelet relative to a sewing machine; an angled base portion on a base end of the elongated planar medial portion, wherein the angled base portion has a base guide hole extending therethrough, and the angled base portion is angled relative to the face surface; and a skew distal end portion on a distal end of the elongated planar medial portion, wherein the skew distal end portion has a distal guide hole extending therethrough, and the skew distal end portion is skewed about an axis at least substantially aligned with the length of the elongated planar medial portion. In various embodiments, a linear looper thread path extends between the base guide hole and the distal guide hole.
Moreover, certain embodiments are directed to a sewing machine stitch length adjustment mechanism, comprising: a multi-bar linkage operatively secured to a feed dog movement mechanism, wherein the multi-bar linkage is configured to control a feed dog movement path length, and wherein the multi-bar linkage comprises: a first bar having an adjustable effective length between an anchor point and a pivot point; and a second bar extending between the pivot point and the feed dog slider mechanism; and wherein the first bar comprises a retaining spring configured to retain a selected location of the pivot point relative to the anchor point.
In various embodiments, the first bar comprises a rack and pinion adjustment mechanism configured to adjust the location of the pivot point relative to the anchor point. Moreover, the first bar may comprise: a rigid bar member having a slot defined therein and having a gear rack defined on a first side of the slot; a slider configured for movement within the slot, the slider having the pivot point secured thereto and having a rotatable pinion configured to engage the gear rack on the first side of the slot; and wherein rotation of the pinion relative to the gear rack causes the slider to move along a length of the slot. Moreover, the first bar may additionally comprise a retaining spring secured relative to a second side of the slot, wherein the retaining spring is configured to apply a retaining force to engage the slider with the first side of the slot. The retaining spring may be configured to adjustably secure the slider in a particular position within the slot. Moreover, the first bar may additionally comprise a locking fastener configured to selectably secure the slider in a particular position within the slot. In certain embodiments, the location of the pivot point relative to the anchor point is infinitely adjustable between a first position corresponding to a first stitch length and a second position corresponding to a second stitch length, the second stitch length being shorter than the first stitch length.
Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present disclosure more fully describes various embodiments with reference to the accompanying drawings. It should be understood that some, but not all embodiments are shown and described herein. Indeed, the embodiments may take many different forms, and accordingly this disclosure should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
As shown in
Stitch Formation and Stitch Length Adjustment
In operation, stitches are formed at discrete locations along a sewing path extending in a material feed direction that are spaced at substantially uniform intervals (the length of each interval corresponding to the lateral feed dog travel and the stitch length, as discussed herein). At each discrete location, a needle 100 located above a throat plate 101 moves vertically downward, through an aperture of a shoe 102 to punch a hole through the sewn material located on a top surface of the throat plate 101 and to pass through an aperture extending through the throat plate 101. The tip of the needle 100 defines a thread aperture extending laterally therethrough, and a needling thread passes through the thread aperture of the needle 100 (a first end of the needling thread is secured relative to a prior-formed stitch, and a second end of the needling thread is located at a needling thread supply). Thus, movement of the needle through the throat plate aperture pushes a needling thread loop through the hole created in the material, and through the aperture of the throat plate 101 such that it is available for manipulation below the throat plate 101 of the sewing machine 10.
The movement of the needle 100 (and needling thread) is coordinated with the movement of a looper mechanism 200 (and looper thread) shown in the side-view of
As mentioned, the movement of the feed dog 250 is coordinated with the movement of the needle 100 and the looper 200. Once the needle 100 retracts above the top surface of the material, the feed dog 250 engages the bottom surface of the material (e.g., by extending at least partially above the top surface of the throat plate 101) and moves at least substantially laterally in the material feed direction to advance the material to the next stitch location. As the feed dog 250 moves the material, the loosely formed lock stitch on the bottom surface of the material is tightened by the movement of the material relative to the movement of the looper mechanism 250. This tightens the lock stitch to secure the lock stitch relative to the material prior to forming the next lock stitch at the subsequent stitch location, spaced a distance away from the previous lock stitch equal to the stitch length. The process of plunging the needle 100 through the material, and looping the looper thread around the needle thread is repeated while the feed dog 250 drops below the top surface of the throat plate 101 and moves back in the direction opposite the material feed direction prior to advancing the material again.
All of the components of the sewing machine 10 are driven by at least one motor providing rotational motion to at least one drive shaft 220 configured to provide rotational forces to various components of the sewing machine 10. In certain embodiments, the sewing machine 10 may comprise two drive shafts—an upper drive shaft configured to drive the vertical motion of the needle 100 (e.g., via a rotational-to-linear motion conversion mechanism, such as a mechanical linkage), and a lower drive shaft 220 configured to drive the motion of the looper mechanism 200 and feed dog 250 of the sewing machine. As shown at least at
As shown in
A distal end opposite the driven end of the auxiliary shaft 221 is secured at an anchored end of a first bar 230 such that movement of the auxiliary shaft 221 causes movement of the first bar 230. As shown in
A distal end of the second bar 240 (opposite the pin point 241) is secured relative to a feed dog slider mechanism comprising a vertical slide rod 243 configured to slide relative to a feed dog slider 244, which is configured to slide (with the vertical slide rod 243) along a horizontal slide rod 245. Specifically, the distal end of the second bar 240 is rotatably secured to a lower end of the vertical slide rod 243 at pivot point 242. The vertical slide rod 243 is pinned at the lower end relative to the distal end of the second bar 240 and relative to a swing arm 225 extending at least substantially perpendicular to a drive shaft axis and a pivot point 242 axis between a distal end of the drive shaft 220 and the pivot point 242. The upper end of the vertical slide bar 243 is pinned to the feed dog 250. The vertical slide rod 243 is configured to slide vertically within the feed dog slider 244 which is configured for lateral movement relative to the horizontal slide rod 245 that is secured relative to the sewing machine housing 210. Thus, the vertical slide rod 243 is configured to move vertically within the feed dog slider 244, and is configured to move horizontally with the feed dog slider 244 along the stationary horizontal slide rod 245.
In use, the auxiliary shaft 221 moves, thereby moving the first bar 230 of the multi-bar linkage, which moves the second bar 240 of the multi-bar linkage. The second bar 240 of the multi-bar linkage applies vertical forces to the lower end of the vertical slide bar 243 (which causes the vertical slide bar 243 to move vertically within the feed dog slider 244 to move the feed dog 250 vertically) and horizontal forces to the vertical slide bar 243 (which causes the vertical slide bar 243 and the feed dog slider 244 to move horizontally along the horizontal slide bar 245, thereby moving the feed dog 250 horizontally). As the auxiliary shaft 221 moves, the multi-bar linkage causes the feed dog 250 to move at least substantially elliptically (including the vertical and horizontal movement components discussed above) to move the sewn material in the material feed direction. The feed dog 250 moves (1) in a direction substantially opposite the material feed direction while an upper surface of the feed dog 250 is below the top surface of the throat plate 101, (2) upwards to engage a bottom surface of the material and to breach the upper surface of the throat plate 101, (3) in the material feed direction while the feed dog 250 is located at least partially above the throat plate 101, and (4) downward such that the upper surface of the feed dog 250 moves below the upper surface of the throat plate 101, before repeating the at least substantially elliptical motion path.
As mentioned herein, the feed dog travel path is adjustable to vary the stitch length of the sewing machine 10. In certain embodiments, the stitch length may vary between about 2 stitches per inch to about 3.5 stitches per inch.
The pin point 241 is secured relative to a slider 231 configured to slide within a corresponding slot 232 of the first bar 230. In the illustrated embodiment, the slider 231 has a shape corresponding to the shape of the slot 232 to enable the slider 231 to slide easily relative to the slot 232. For example, the slider 231 may have a generally arcing shape configured to correspond to the arcing shape of the slot 232. As yet another example, the slider 231 may have a generally rectangular shape configured to correspond to a generally linear shape of the slot 232. Moreover, as shown in
As shown in
A first side of the slot shown in
As shown in
In the embodiment of
Adjustment of the effective length of the first bar 230 according to the embodiment of
The slider may additionally comprise a locking fastener (e.g., screw) secured at the pin point 241 that may be engaged once a desired effective length of the first bar 230 is selected. As shown in
Thus, to change the effective length of the first bar 230 (and therefore to change the stitch length of the sewing machine 10), a user first loosens the locking fastener to enable movement of the slider 231 relative to the slot 232 in the first bar 230. The locking fastener may be loosened via a corresponding tool configured to engage a tool engagement feature of the locking fastener.
Once the locking fastener is loosened, the user may engage a tool with the pinion 235 of the slider 231, and may turn the pinion 235 relative to the slider slot's gear rack 234 to move the pinion 235 (and the slider 231) toward or away from the anchor point of the first bar 230. Moving the slider 231 away from the anchor point increases the effective length of the first bar 230 by moving the pin point 241 between the first bar 230 and second bar 240 away from the anchor point of the first bar 230. This therefore enables a longer horizontal motion path of the vertical slide bar 243, which provides a longer stitch length of the sewing machine 10. Moving the slider 231 toward the anchor point decreases the effective length of the first bar 230 by moving the pin point 241 between the first bar 230 and second bar 240 toward the anchor point of the first bar 230. This therefore enables a shorter horizontal motion path of the vertical slide bar 243, which provides a shorter stitch length of the sewing machine 10.
As shown in
Looper Thread Tension Adjustment
As mentioned, adjusting the stitch length of the sewing machine 10 modifies the amount of tension applied to the looper thread below the throat plate 101. Increasing the stitch length (e.g., by increasing the distance the material is moved by the feed dog 250 between stitches) increases the amount of tension applied to the looper thread because the looper thread is directly connected to the previously formed stitch, which is moved away from the looper as the material is advanced by the feed dog 250. Likewise, decreasing the stitch length causes a corresponding decrease in the amount of tension applied to the looper thread while the material is moved by the feed dog 250.
Although small changes in the amount of tension on the looper thread are unlikely to change the functionality and/or effectiveness of the looper mechanism 200 as it reciprocates around the needle path to loop the looper thread around the needling thread and to tie a locking stitch with the looper thread and the needling thread, large changes in looper thread tension may cause the sewing machine 10 to miss stitches, to bunch the material on the throat plate 101, and/or to break the looper thread as the material is advanced. For example, a large increase in stitch length may cause the tension in the looper thread to apply a strong tensile force on the material being moved, such that the material is caused to bunch on the throat plate 101. The tensile force is applied to the material at the location of a previously formed stitch, and the feed dog 250 may be configured to push material behind the previously formed stitch in the material feed direction. The tension formed on the previous stitch by the looper thread may be sufficient to hold the material at its current location, while additional material is pushed against the prior stitch, thereby bunching the material between adjacent stitches. Alternatively, increasing the tension on the looper thread may be sufficient to overcome the tensile strength of the looper thread, thereby causing the looper thread to snap as the material is advanced.
On the other hand, decreasing the tension in the looper thread by decreasing the stitch length may create undesirable slack in the looper thread (e.g., between the looper mechanism 201 and the looper thread feed mechanism, and/or between the looper mechanism 201 and the previously formed stitch). The reciprocal movement of the looper mechanism 201 may cause the looper thread with the additional slack to sway or whip, which may position the looper thread in an undesirable position relative to the needle path as the needle 100 plunges through the material and the throat plate. The improper positioning of the looper thread prevents the formation of a proper locking stitch between the looper thread and the needling thread, thereby causing the sewing machine to miss a stitch.
The illustrated embodiment comprises an adjustable looper thread take-up eyelet 500 configured to adjust the looper thread path length of the looper thread at a position proximate the looper mechanism 200. As shown in
As shown therein, the looper thread path 50 extends from a previously formed stitch, through an aperture in the distal end of the looper arm 201, along the length of the looper arm 201 and through a second hole located at the base of the looper arm 201, before extending along an at least substantially linear portion of the looper thread path 50 to the distal guide hole 504 of the adjustable looper thread take-up eyelet 500 discussed above. The looper thread path 50 turns at the distal guide hole 504 and extends along another at least substantially linear portion from the distal guide hole 504 along the length of the adjustable eyelet 500 to the base guide hole 503 before extending across the base of the sewing machine to the looper thread source.
As shown in
The adjustable eyelet 500 is adjustable between an extended position and a retracted position. In the extended position, the adjustable eyelet extends beyond a portion of the sewing machine housing 210 by a first distance, and one of the one or more fasteners 510 is adjacent a first end of the adjustment slot 502 proximate the base portion 505 of the adjustable eyelet 500. In the retracted position, the adjustable eyelet 500 extends beyond a portion of the sewing machine housing 210 by a second distance that is less than the first distance, and one of the one or more fasteners 510 is adjacent a second end of the adjustment slot 502 proximate the distal end portion 506 of the adjustable eyelet 500.
Changing the positioning of the adjustable eyelet 500 between the extended position and the retracted position changes the overall length of the looper thread path 50 (including the length of the portion of the looper thread path between the distal end of the adjustable eyelet and the previous stitch, which extends through the looper arm 201), and changes the angle of the looper thread path 50 defined between the first direction extending parallel to the planar medial portion 501 of the adjustable eyelet 500 and the second direction extending from the distal guide hole 504 to the looper mechanism 200. These changes in looper thread path length and angle may cause a change in back-tension on the looper thread. Thus, decreasing the back-tension on the looper thread by moving the adjustable eyelet 500 toward the retracted position to decrease the looper thread path length may enable the sewing machine 10 to effectively implement a longer stitch length by minimizing potentially detrimental effects of high looper thread tension that could lead to broken looper threads and/or bunched material. Moreover, increasing the back-tension on the looper thread by moving the adjustable eyelet 500 toward the extended position to increase the looper thread path length may enable the sewing machine 10 to effectively implement a shorter stitch length by minimizing potentially detrimental effects of low looper thread tension that could lead to excessive looper thread drape or slack between the previously formed stitch and the looper arm 201 which may ultimately sway and/or whip and thus impact the positioning of the looper thread during lock stitch formation. For example, providing a longer looper thread path 50 may provide a decreased thread slack and/or drape (the distance between a theoretical linear thread path and the maximum amount of thread drape or sag of the looper thread), which may impede excessive swaying or whipping of the thread relative to the various components of the looper mechanism 200.
The adjustable eyelet 500 may be adjusted between the extended position and the retracted position by at least partially loosening the one or more fasteners 510 (e.g., at least partially unscrewing the one or more fasteners 510) to enable the adjustable eyelet 500 to slide relative to the one or more fasteners 510. Once the adjustable eyelet 500 is positioned as desired, the one or more fasteners 510 are tightened to secure the adjustable eyelet 500 in the desired position.
Many modifications and other embodiments will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosure is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
This patent application claims priority from U.S. Provisional Appl. Ser. No. 62/569,045 filed Oct. 6, 2017, which is incorporated herein by reference in its entirety.
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