Chang, Steve (382 Route 304 Bardonia, NY, 10954, US)
| 1. | ] [CLAIM 1] An automatic dual bobbin mechanism comprising: two bobbins respectively arranged in a first position defining a stitchingthread supply position and a second position defining a threadrespooling position, wherein the bobbin in the first position facilitates stitching with a stitching thread winded off the bobbin in the first position and the bobbin in the second position facilitates respooling with a supplying thread spooled the bobbin in the second position; two bobbin casings respectively containing each of the two bobbins and respectively including a thread supplying hole so that the supplying thread passes through the thread supplying hole and a needle operates in an out through the thread supplying hole; a rotating means exchanging the positions of the two bobbins by rotating the two bobbins to 180 degrees; a thread transfer means transferring the thread supplied for the bobbin in the first position from the bobbin in the first position to the bobbin of the bobbin casing in the second position after rotating and exchanging the positions of the two bobbins in order to supply the thread for the bobbin in the second position; a bobbin driving portion rotating the bobbin in the second position; a housing containing the two bobbin casings. [CLAIM 2] A dual bobbin mechanism according to claim 1, wherein the respect bobbin casing further includes a tension control means for the supplying thread adjacent to the thread supplying hole. [CLAIM 3] A dual bobbin mechanism according to claim 2, wherein the tension control means for the supplying thread includes an arrow head shaped spring arranged opposite to the direction of rotation of the bobbin casing with respect to the thread supplying hole of the bobbin casing and a control means to control the gap between the spring and the bobbin casing. [CLAIM 4] A dual bobbin mechanism according to claim 1, wherein the control means includes two screws to control the gap between the spring and the bobbin casing. [CLAIM 5] A dual bobbin mechanism according to claim 1 further including a mount wherein each of the bobbin casings are mounted on the mount and the rotating means rotates the mount. [CLAIM 6] A dual bobbin mechanism according to claim 5, wherein the mount is attached and rotates along the inner diameter of the housing. [CLAIM 7] A dual bobbin mechanism according to claim 1, wherein the respect bobbin casing further includes a thread transfer groove extended from and communicating with the thread supplying hole toward a side of the bobbin casing and the thread transfer means transfers the supplying thread along the thread transfer groove of the bobbin casing located in the second position. [CLAIM 8] A dual bobbin mechanism according to claim 1 further including a fixing means holding the bobbin casings respectively located in the first and second position. [CLAIM 9] A dual bobbin mechanism according to claim 8, wherein the fixing means for the bobbin casings further includes a first and a second fixing holes formed on the bobbin casing, a first and a second driving members having corresponding shapes of the first and the second fixing holes respectively, a release means removing the first and second driving members from the first and second fixing holes before the rotating means operates. [CLAIM 10] A dual bobbin mechanism according to claim 1 further including a cover fixing the respect bobbin in the bobbin casing and having a male corresponding to a rotation axis of the bobbin, the male engaged with the rotation axis when the bobbin is contained in the bobbin casing. [CLAIM 11] A dual bobbin mechanism according to claim 1, wherein the respect bobbin has an indentation so that the supplying thread transferred to the bobbin casing in the second position by the thread transfer means is caught and cut in the indentation. [CLAIM 12] A dual bobbin mechanism according to claim 11 further including thread cutting rings respectively attached to the indentation of each bobbin. [CLAIM 13] A dual bobbin mechanism according to claim 1, wherein the bobbin driving portion rotates the bobbin in the second position so that the bobbin in the second position has the same rotation speed as the rotation speed of the bobbin in the first position. |
[TECHNICAL FIELD OF INVENTION] This invention relates to a bobbin mechanism for a sewing machine, specifically an automatic dual bobbin mechanism.
[CONVENTIONAL ART OF INVENTION] The sewing machine uses two kinds of threads to properly join two pieces of fabric. Namely, the one is the thread with which a needle is threaded, and the other is the thread supplied by the second thread source, or a bobbin.
However, bobbins are extremely limited in their thread capacity and frequently required exchanging. That is to say, once a bobbin is emptied of its thread, a sewing machine operator would have to stop the stitching process, manually remove the empty bobbin, replace it with a full bobbin, rethread the needle hook and needle and resume stitching.
Such a process of changing bobbins becomes a time consuming process and sometimes leads to poor garment construction or damages the delicate fabrics being joined. Thus, there arises a need for a bobbin mechanism that has an increased thread supply or is capable of continuous bobbin replacement feeding to reduce"down time" during sewing machine operation.
In order to satisfy such a need, Rovin et al. teaches an automatic bobbin rewinding mechanism in the U. S. Pat. No. 4,002,130. However, the procedure of transferring the bobbins from rewinding to sewing positions requires various mechanical components including actuators, cams, gear drives, etc., which results in a bulky frame needing to be bolted to the existing sewing machine.
Further, the U. S. Pat. No. 5,143,004 by Mardix et al. and the U. S. Pat.
No. 4,681,050 by Kosmas are suggested.
Despite the advances in bobbin rewinding and transfer technology, there still is a need for improved thread run-out detection and transfer of bobbins for smooth, continuous operation without the addition of bulky frames attached to the existing machines or extra steps to rethread hooks or refill bobbins.
To satisfy the above need, the inventor of the present invention already suggested the U. S. Pat. No. 5,143,004.
In a preferred embodiment of the U. S. Pat. No. 5,143,004, two bobbins nestled in a side-by-side configuration are located inside a housing, a second bobbin is refilled during a first bobbin is used, and if the thread of the first bobbin runs out, the second bobbin becomes used by rotating the bobbins for 180 degrees so that a continuous sewing is accomplished.
However, in that preferred embodiment of the U. S. Pat. No. 5,143,004, there is no means to control tension of the thread supplied to the bobbin, and since the first and second bobbins are connected by a male and female connection in order to rotate together, there is a problem that the thread can be cut between the male and female or the thread is over-tensed.
Further, the thread is cut from the full bobbin thread at an indentation of the bobbin depending on tension. Since the cutting depending on tension is not so effective in cutting the thread, the sewing machine may operate irregularly.
Further, an additional fixing means is needed to hold a bobbin casing located in sewing position.
Furthermore, there is a problem that the bobbin casing can not rotate stably.
[DETAILED DESCRIPTION OF INVENTION] Accordingly, the present invention is contrived to overcome the above- mentioned problem of the conventional invention. It is an object of the present invention to provide an automatic dual bobbin mechanism that accepts the basic concept of the early U. S. patent of the subject inventor and is applicable to an actual sewing machine.
That is to say, the present invention provides the automatic dual bobbin mechanism that a supplied thread can be cut well at a position between bobbins that are located in refilling and sewing positions respectively.
Further, for another object, the present invention provides the automatic dual bobbin mechanism wherein bobbin casings can rotate stably.
Furthermore, for another object, present invention provides the automatic dual bobbin mechanism that can control tension of a supplied thread.
To accomplish the above-mentioned objects, the present invention has the first characteristic that two bobbins rotate independently with each other. Namely, in the present invention, the two bobbins do not contact with each other and a bobbin in refilling position is rotated by a driving means.
The second characteristic of the present invention is that tension of the thread supplied from a bobbin can be controlled. For this purpose, the present invention provides a tension control means.
The third characteristic of the present invention is that the bobbin casing is supported stably in a housing by a bobbin casing mount. The bobbin casing is mounted on the bobbin casing mount and both the bobbin casing and the mount rotate to 180 degrees inside the housing. When the mount rotates, the driving means of the refilling bobbin is removed from the bobbin casing.
The present invention having the above characteristics provides two bobbins respectively located at a first position defined as sewing position and a second position defined as refilling position; two bobbin casings respectively containing each bobbin and having a hole formed on a position corresponding to the center of rotation of the bobbin and a through hole that a supplied thread passes through and a needle operates in and out; a rotating means that rotates the two bobbin casings for 180 degrees so as to change the positions of the two bobbin casings; a bobbin driving portion that rotates the bobbin located in the second position.
Preferably, the present invention further includes a tension control means for the supplied thread in the bobbin casing.
It is preferred that the tension control means includes a gap between a spring attached at the through hole of the bobbin casing and the bobbin casing and screws controlling the gap.
The present invention further includes a bobbin casing mount, which rotates to 180 degrees inside the housing by the rotating means.
The respect bobbin of the present invention has an indentation on the circumference of at least one side of the bobbin, and a thread cut ring.
Each of the bobbin casings has a thread transfer groove. As the bobbins change positions, the thread moves from the thread filling bobbin to the thread exhausted bobbin via the thread transfer grooves. At that time, a thread transfer part near the thread exhausted bobbin catches the thread, and the thread is cut by the thread cutting ring attached at the indentation of the bobbin.
The extra characteristics and objectives of the present invention are shown by an embodiment explained as follows.
BRIEF EXPLANATION OF FIGS] FIG. 1 is an exploded perspective view of a bobbin mechanism according to the present invention.
FIG. 2A and 2B are top and bottom views of the bobbin casing, respectively.
FIG. 3 shows the operation of the process that the holding of the bobbin casings is freed.
FIG. 4 is a perspective view illustrating a bobbin in a refilling position with a driveshaftand a cover of the bobbin casing combined.
FIG. 5A is a cross-sectional view illustrating the feature of a thread cutting ring.
FIG. 5B is a perspective view illustrating that the thread cutting ring of the FIG. 5a is attached toward an indentation of the bobbin according to the present invention.
FIG. 6A, 6B and 6C are respectively simplified top views showing the bobbin casings during rotation at different rotating angles.
[THE BEST MODE FOR INVENTION j FIG. 1 is an exploded perspective view of a bobbin mechanism according to the present invention. As shown in FIG. 1, an embodiment of the present invention has two bobbins 11 and 21, and the bobbin located at the left of the drawing is defined as the bobbin in sewing position 11 and the right bobbin is defined as the bobbin in refilling position 21. These bobbins are respectively contained inside the bobbin casings 31 and 41 with covers 13 and 23, and each bobbin casing has a shape of a hemisphere or a dish.
Each of the bobbin casings 31 and 41 is mounted on a bobbin casing mount 50 (defined as a mount hereinafter). For the purpose of mounting, the bobbin casing mount 50 has a mounting portion that is formed to be round like the shape of edges 32 and 42 of the bobbin casings. At the upper edge of the mount, a male 51 is formed in order to mount the mount at a rounded groove 2 of a housing 1. The mount 50 can rotate to 180 degrees along the rounded groove 2 of the housing 1.
However, each of the bobbin casings 31 and 41 has two fixing holes. First fixing holes 33 and 43 prevent the bobbin casing 41 in the refilling position from rotating according to the rotation of the bobbin inside the bobbin casing 41, and the second fixing holes 34 and 44 prevent the rotation of the bobbin casing 31 in the sewing position. In order to prevent the rotation of the bobbin casing 41 in the refilling position, a bobbin fixing male 63 having a shape and a position corresponding to the first fixing hole 43 of the bobbin casing 41 can protrude inside the housing 1. Though the fixing male has a shape of butterfly in this embodiment, the shape of the fixing male is not limited. This bobbin fixing male 63 is formed at an end of a first driving member 60. Since the fixing
first groove 43 plays a role to fix the hemisphere bobbin casing 41, the first fixing hole 43 is preferably located on the center of the bobbin casing 41.
However, the bobbin 21 in the refilling position is rotated independently. For the rotation of the bobbin 21, a bobbin driveshaft70 is located at the corresponding position of a rotation axis 22 of the bobbin 21. Since the bobbin 21 is located at the center of the bobbin casing 41, the bobbin driveshaft70 passes through the center of the bobbin casing 41.
That is to say, the bobbin 21 in the refilling position rotates with both an axis 24 formed on the cover 23 and the bobbin driveshaft70 supporting the bobbin. Thus, as shown in the FIG. 1, the bobbin fixing male 63 of the bobbin driveshaft 70 that located at the center of the bobbin casing passes through the bobbin. The bobbin driveshaft 70 may have a sectional shape of a circle or a polygon like rectangular.
The second fixing holes 34 and 44 of the bobbin casings 31 and 41 are fixed by a second driving member 80 having another fixing male 84 that has a shape and a position corresponding to the second fixing hole. This driving member has an identical shape of the one used to fix the bobbin casing in a conventional bobbin mechanism.
And, the rotation of the mount 50 is facilitated by a pivot coupler 90 located under the bobbin mechanism. The pivot coupler 90 has two pins 92 so that the pins are inserted into two corresponding holes 52 formed on the mount 50. The pivot coupler is explained again when the operation of the mechanism is explained.
Further, not shown in the FIG. 1, there is another driveshaft that drives the housing 1, and the housing driveshaft rotates, for example, to 7000 rounds per minute.
Since the configuration of the housing driveshaft is the same as that of the conventional one, a detailed explanation can be omitted. Also, the housing 1 has the same shape of the
conventional one. But the housing 1 differs from the conventional one in that it has the removable mount.
FIG. 2A is a plan view illustrating a bobbin casing seen from the direction over the first fixing hole. The two bobbin casings have the identical shapes, and the bobbin casing in the refilling position is explained as a standard.
The second fixing hole 44 is placed at the upside of the first fixing hole 43 on the bobbin casing 41. A thread supplying hole 45 through which thread is supplied and a needle operates is formed at the upside of the second fixing hole 44 on the bobbin casing 41.
Further on the bobbin casing 41, a thread transfer groove 46 connected with the upper portion of the thread supplying hole 45 is formed. At one side of the thread supplying hole 45, a spring 47 having a shape of arrow head is placed. The shape of arrow head means that the spring has an inclined portion 47a like an arrow head and a stepped portion 47b. Though the name of spring is used, it means that the spring 47 controls the tension of the thread and is different from the meaning of the conventional spring having the restoration force.
The spring 47 is located opposite to the direction of rotation with respect to the thread supplying hole 45. Namely, if the thread transfer groove 46 moves toward right of the drawing by a clockwise rotation of the bobbin casing 41, the spring 47 is located at the upside with respect to the thread supplying hole 45. As the thread supplied through the thread supplying hole 45 fills the bobbin and the winding diameter becomes larger, the supplied thread is transferred along the inclined portion 47b of the spring 47 and latched by the stepped portion 47b so that the position of the supplied thread is fixed.
However, the spring is attached by screws 48 and 49, one of which is to attach the spring and the other is to control the gap between the spring 47 and the bobbin casing 41. That is to say, tension of the supplied thread is controlled by controlling the screws 48 and 49 so that the user can control the tension of the supplied thread with respect to the thickness of the thread or types of stitching.
FIG. 2B is a plan view of the bobbin casing of FIG. 2A seen from the direction opposite to that of FIG. 2A. As shown in FIG. 2B, the bobbin casing contains a bobbin (not shown) inside and the cover 23 covers the back of the bobbin casing.
FIG. 3 is a simplified perspective view illustrating a mechanism that a first and second driving members which hold the bobbin casing and a bobbin driveshaft and the like are released from the bobbin casing.
As shown in FIG. 3, the first driving member 60 and the bobbin driveshaft 70 are connected with a release member 75 and all of them are formed as one member. The release member 75 and the second driving member 80 are respectively linked by links 82 and 83 toward the bobbin casings. The end portions of the links 82 and 83 contact with each other. Pushing the contacting end portions toward the bobbin casings 31 and 41, the links 82 and 83 are pushed away, and the distance d between the release member 75 and the second driving member 80 becomes longer so that the holding of the bobbin casings 31 and 41 is released.
However, the release member 75 is attached by a return spring 94 in order to restore the position of the release member so that if the pushing force to the links 82 and 83 are released, the release member returns to its earlier position so that the second driving member and the bobbin driveshaft hold the bobbin casings again.
FIG. 4 shows that the cross-section of the bobbin driveshaft is rectangular. The bobbin driveshaft having a polygonal cross-section has an advantage in driving the bobbins.
The bobbin is rotated by the bobbin driveshaft with a cover male 24 of the cover supporting the bobbin.
However, FIG. 5A shows the feature of thread cutting rings 17 attached to the indentations 15 which are respectively formed at each of the bobbins 11 and 21, and Fig.
5B is a perspective view illustrating that the thread cutting ring is attached to the indentation 15 of the bobbin 11. The thread cutting ring has an inclined portion 17a and is attached on the outer surface of the indentation side of each of the bobbins 11 and 21 by grooving the outer surface. The thread cutting rings can be attached to the bobbins 11 and 21 by various methods.
Thus, with a downward force, the thread caught in the indentation 15 becomes caught in the thread cutting ring 17 and cut along the inclined portion 17a.
Hereinafter, the operation of a bobbin mechanism of the embodiment having the above-described configuration is explained.
Sewing proceeds in a normal fashion with needle thread being hooked by the rotating housing 1, creating a loop by turning around the bobbin casing 3 land catching the bobbin thread from the bobbin 11 in the sewing position in the loop created to complete the required stitch pattern. The thread spooled at the bobbin 11 in the sewing position is preset either by manual digital counter or by computerized monitoring which detects the number of revolutions of the bobbin 11. Once the preset number of bobbin revolutions is reached and the thread spooled at the bobbin 11 is wholly exhausted, the needle is stopped and the rotation of the bobbin 11 is also stopped.
However, while the thread spooled at the bobbin 11 is stitching, the bobbin 21 in the refilling position is rotating at the same speed as the bobbin 11 by the bobbin driveshaft 70 and it is being refilled by a thread supply portion.
Once the rotation of the bobbin 11 is stopped as the preset number of bobbin revolutions is reached, the pivot coupler 90 elevates and the two pins 92 of the pivot coupler 90 engage into the holes 52 formed on the mount 50.
At this point, as shown in FIG. 3, the first and second driving members 60 and 80 are removed from the bobbin casings 31 and 41 so as to enable the rotation of the bobbin casings smoothly.
In a preferred embodiment of the invention, the pivot coupler 90 is connected to a solenoid which receives an electrical signal from the existing sewing machine components and rotates the bobbin casings. The pivot coupler may also be activated by other means and include, but are not limited to, other electromagnetic, magnetic or electromechanical means.
Once the bobbin revolution counter reaches the preset value or the first and second driving members are removed, it will trigger the mechanism for rotating the mount 50.
FIG. 6A, 6B and 6C are respectively simplified top views illustrating the process that the two bobbin casings are rotating and the supplied thread travels or is cut.
They are explained with reference to the various components of FIG. 1. FIG. 6A illustrates that the thread of the bobbin 11 in the sewing position gets operated, and the supplied thread 100 is winded at the bobbin 21 in the refilling position at the same time.
The supplied thread 100 supplied to the bobbin 21 in the refilling position is transferred from a thread supplying pipe 95 and winded at the inside bobbin 21 through the thread
supplying hole 45 of the bobbin casing 41. Herein, as the quantity of the supplied thread 100 filling the bobbin 21 increases, the supplied thread gradually travels to the arrow head spring 47 and is caught by the step portion 47b of the spring.
However, when the thread of the bobbin 11 in the sewing position is wholly exhausted, each of the bobbins 11 and 21 and the housing 1 stop rotating, and the bobbin casings 31 and 41 are rotated by the pivot coupler 90 attached at the downside mount 50.
As shown in FIG. 6B illustrating the state that the bobbin casings rotate to 90 degrees, the supplied thread 100 is still caught by the spring 47 of the bobbin casing 41 which is spooled by the supplied thread.
As shown in FIG. 6C illustrating the state that the bobbin casings rotate to 180 degrees, a transferring member (not shown) which transfers the supplied thread 100 toward the thread transfer groove moves down from upside. The transferring member is preferably hook-shaped.
At this point, the first and second driving members 60 and 80 which moved back hold the bobbin casings 31 and 41 again to stabilize the bobbin casings, and the pivot coupler 90 is removed from the mount 50 again.
FIG. 6 illustrates that the moving back transferring member 88 enter the empty bobbin casing 41 (though the bobbin casing in this position is the bobbin casing identified as the reference number 31 herein-before, the reference numbers change as the bobbin casings rotate, thus, hereinafter, the reference number is assigned accordingly), and is caught in the indentation 15 of the bobbin 21. As the transferring member 88 moves down, the supplied thread 100 caught in the indentation 15 of the bobbin 21 is cut by the thread cut ring 17 attached to the indentation while the end of the portion of the
thread 100 which is connected with the thread supplying pipe 95 is still caught in the inclined portion 17b of the thread cutting ring 17.
After that, the needle moves down to the thread supplying hole 35 of the thread filling bobbin casing 31 and facilitates stitching with the supplied thread caught in the spring 37 of the bobbin casing 31. The thread exhausted bobbin 21 rotates at the same speed as the bobbin 11 and is refilled all the while.
However, the supplied thread 100 is preferably supplied from a tension roller which rotates during pulling in the thread and rewinds the thread when releasing the thread like a tape measure.
Herein-before, while the preferred embodiment of the invention has been described in detail, the above-described embodiment does not limit the scope and spirit of the subject invention. Namely, various methods may be applicable to such as the shape of the transferring member, the apparatus detecting the number of the rotations or releasing and holding of the driving members. Accordingly, though various variations and modifications are to be considered, these variations are within the scope and spirit of the subject invention according to the enclosed claims.
As described above, by the automatic dual bobbin mechanism according the subject invention complements the U. S. patent of the subject inventor sufficiently so that all the actual problem may be overcome.
That is to say, in the subject invention, the supplied thread is cut well between the bobbins in the refilling position and the sewing position, a stable rotation of the bobbin casings is guaranteed, and the tension of the supplied thread can be controlled.
Particularly, since the bobbin casings are rotated independently, the thread passing through connection portions of male and female structure between the bobbin casings does not get an over-tension.
Further, the problem of adopting a complicate configuration for exchanging the bobbins is solved.