EP3875654B1

EP3875654B1 - Sewing machine with adjustable double needle distance

Info

Publication number: EP3875654B1
Application number: EP20202657.1A
Authority: EP
Inventors: Hsu Hui Chen
Original assignee: Chee Siang Industrial Co Ltd
Current assignee: Chee Siang Industrial Co Ltd
Priority date: 2020-03-04
Filing date: 2020-10-19
Publication date: 2023-07-19
Anticipated expiration: 2040-10-19
Also published as: JP2021137550A; KR20210113018A; KR102466108B1; TW202134498A; EP3875654A1; JP7098704B2; TWI722814B

Description

FIELD OF THE INVENTION

The present invention relates to a double needle sewing machine, and more particular, to a sewing machine with adjustable double needle distance, which allows adjustment of a distance between two needles thereof during a sewing operation.

BACKGROUND OF THE INVENTION

Due to the development in automated and high-speed sewing machine field, many currently available industrial sewing machines are not only labor-saving and highly efficient in production, but also include various models providing functions to fulfill different purposes. For example, there are a single needle pattern sewing machine that has an XY-axis driver to automatically move a sewing workpiece and enables freely changeable sewing paths; a single needle rotatable head pattern sewing machine that can further maintain consistent stitches in sewing lines of different directions; and a double needle rotatable head pattern sewing machine that is able to form two equally spaced curved sewing lines.
Among others, two parallel sewing lines formed using a double needle sewing machine create better aesthetic effect on the sewing workpiece, so that double needle sewing is frequently applied to form patterns on various clothing in people's daily life. Figs. 1A and 1B illustrate a computer-controlled, double needle rotatable head pattern sewing machine 80. On a top of the double needle rotatable head pattern sewing machine 80, there is a sewing head rotating unit 81; and a base rotating unit 82 and an XY-axis feeding unit 83 are located below the sewing head rotating unit 81. The sewing head rotating unit 81 can bring a needle bar 84 to rotate, so that a needle holder 85 mounted to a lower end of the needle bar 84 can synchronously bring two mutually spaced needles 86 to rotate. When the needle bar 84 is rotating, the base rotating unit 82 also brings a needle plate 87 and a base (not shown) of the sewing machine to rotate, so that two needle holes 871 on the needle plate 87 can always be aligned with the two needles 86 in one-to-one correspondence. The XY-axis feeding unit 83 includes a jig, via the jig the sewing workpiece is brought to move in the x-axis direction and the y-axis direction as indicated in Fig. 1A. In this way, the sewing head rotating unit 81, the base rotating unit 82 and the XY-axis feeding unit 83 can cooperate with one another to form two juxtaposed parallel sewing lines on the sewing workpiece. In this way, the sewing machine 80 can replace the conventional manually operated double sewing machine and to upgrade the efficiency of sewing operation.
However, there are various types of sewing workpiece materials. Some of the workpiece materials are relatively thick while others are relatively thin; and some of the workpiece materials are relatively soft while others are relatively rigid. Different sewing workpiece materials would require different double needle distances and different stitch lengths. Generally, the distance between the two needles 86 of the double needle rotatable head pattern sewing machine 80 has to be larger when sewing relatively thick or rigid workpiece materials. On the other hand, the distance between the two needles 86 of the double needle rotatable head pattern sewing machine 80 has to be smaller when sewing relatively thin or soft workpiece materials. Therefore, when the conventional double needle rotatable head pattern sewing machine 80 is used to sew workpieces of different material conditions, the sewing machine 80 must be temporarily stopped to allow the sewing operator to manually replace the needle holder 85 and the needle plate 87 to another suitable ones. That is, whenever the conventional double needle rotatable head pattern sewing machine 80 is to be used for sewing another type of workpiece material, the sewing operator has to take time and effort to replace the needle holder 85 and the needle plate 87, which would have an adverse influence on the upgrading of the sewing efficiency and productivity.
US 3 339 507 A discloses a sewing machine capable of zig-zag movements having a vertically reciprocating hollow tubular needle bar with a special oscillatory actuating means therewithin which cause two needles pivotally attached to the needle bar, and each having a flat tang of a oscillate in a horizontal plane independently toward and away from each other, to produce symmetrical left and right patterns of stitches.
US 5 765 493 A discloses a sewing machine including a needle bar for mounting two needles separated by a distance in a principal shaft direction; a principal drive shaft for driving the needle bar and extending in the principal shaft direction; a bed portion; a first loop taker disposed in the bed portion; a transmission system for connecting movement between the first loop taker and the principal drive shaft; a loop taker module detachably provided to the bed portion; a second loop taker provided to the loop taker module; and servomotor provided in the loop taker module and for driving the second loop taker.
Concerning CN 102 605 560 B , the chain stitch is mostly used for sewing the knitted goods. The document discloses a double-needle belt loop sewing machine with position-adjustable rotating shutters. The double-needle belt loop sewing machine comprises a base and a head, the head is provided with a first needle and a second needle which are capable of vertically moving, a first rotating shuttle and a second rotating shuttle are arranged in the base, the first rotating shuttle is matched with the first needle in operation, and the second rotating shuttle is matched with the second needle in operation. A motor drives the first needle, the second needle, the first rotating shuttle andthe second rotating shuttle to cooperate through an upper shaft, a first lower shaft and a second lower shaft, and the first needle and the second needle can be used for correspondingly sewing two ends of a belt loop respectively. The distance between the first rotating shuttle and the second rotating shuttle is adjusted by an adjusting mechanism to adapt to the lengths of different belt loops.
EP 2 565 313 A1 discloses a double needle sewing machine. The double needle sewing machine includes a needle bar turning base supporting two needle bars, a needle bar turning mechanism configured to turn the two needle bars, a clutch mechanism configured to hold the two needle bars, an operating member configured release each of the two needle bars from the clutch mechanism individually, an actuator for switching the position of the operating member, a differential transmission mechanism configured transmit the position switching operation from the actuator and to the operating member. The differential transmission mechanism includes an input member that turns by receiving the drive force from the actuator, an output member that turns to apply the position switching operation to the operating member, a transmission member configured to transmit the turning motion between the input member and the output member such that the turning direction of the turning motion is reversed, and a turning support supporting the transmission member such that the transmission member revolves about the center line. A turning motor serving as a drive source of the needle bar turning mechanism is provided on the sewing machine frame, and a rotation of the turning motor is transmitted to the needle bar turning base and to the turning support such that the rotation ratio of the needle bar turning base to the turning support is 2:1.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide an improved double needle sewing machine by providing a double needle distance adjusting mechanism between a needle bar and two needles of the sewing machine for sidewardly moving at least one of the two needles, so that the two needles are located closer to or farther away from each other to change the distance between them. By adjusting the distance between the two needles with the double needle distance adjusting mechanism, the sewing machine alone can be operated to sew workpieces requiring different double needle distances, which not only enables upgraded production efficiency of the sewing machine, but also saves the labor and time for replacing needle holder and needle plate as in the case of the conventional double needle sewing machine.
Another object of the present invention is to provide a double needle sewing machine, of which at least one of two needles is linearly movable so as to change a distance between the two needles in the course of forming two sewing lines, and a sewing head thereof is rotatable while sewing. Therefore, the distance and the angular position of the two needles relative to each other are freely controllable in the course of sewing. In this manner, the sewing machine can be applied to form a variety of sewing patterns with upgraded aesthetic appearance.
A further object of the present invention is to provide a double needle sewing machine, of which at least one of two needles is sidewardly movable so as to change a distance between the two needles when a needle bar thereof is moving upward and downward. Therefore, the sewing machine can be operated to form a plurality of patterns of parallel sewing lines on the same workpiece, or to form two parallel sewing lines having variable widths along the same sewing path.
To achieve the above and other objects, the sewing machine with adjustable double needle distance according to the present invention includes a sewing head, a double needle distance adjusting mechanism and a double needle distance driving mechanism. The sewing head includes an upper shaft and a needle bar. The upper shaft is rotatable to bring the needle bar to move upward and downward, such that two needles located at a lower end of the needle bar move synchronously with the needle bar. The double needle distance adjusting mechanism includes an adjustment stem axially extended through the needle bar and an adjustment unit located between the adjustment stem and the two needles. The adjustment stem is brought by the double needle distance driving mechanism to rotate, and the adjustment stem in rotating enables the adjustment unit to cause at least one of the two needles to move sidewardly, so that the two needles are located closer to or farther away from each other.
In the preferred embodiment, the sewing machine with adjustable double needle distance further includes two hook bases, a shuttle driving mechanism and a needle hole distance driving mechanism. Each of the two hook bases includes a rotatable shuttle and a needle plate located above the shuttle; and each of the needle plates has a needle hole aligned with one of the two needles. The shuttle driving mechanism is capable of bringing the shuttles on the two hook bases to rotate simultaneously. The needle hole distance driving mechanism is capable of synchronously bringing at least one of the two hook bases to move sidewardly when the two needles are moved closer to or farther away from each other, so that a distance between the two needle holes is the same as a distance between the two needles.
The adjustment unit includes a gear connected to the adjustment stem and a first rack connected to a first one of the two needles. The gear is brought by the adjustment stem to rotate; and the first rack is engaged with the gear, so that the first one of the two needles is moved sidewardly in a first direction across the needle bar by the first rack.
The needle hole distance driving mechanism includes a displaceable first movable block and a rotatable first transmission rod. The first movable block is connected to a first one of the two hook bases. A first screw rod unit is provided between the first movable block and the first transmission rod and is capable of converting a rotational motion into a linear motion. When the first transmission rod rotates in a first rotational direction, the first screw rod unit enables the first movable block to bring the first one of the hook bases to move.
In another preferred embodiment, one side of the gear opposite to the first rack is engaged with a second rack, and the second rack is connected to a second one of the two needles. Whereby, the second rack brings the second one of the two needles to move sidewardly in a second direction opposite to the first direction when the gear rotates and the first rack brings the first needle to sidewardly move in the first direction.
In addition, the needle hole distance driving mechanism further includes a second movable block connected to the second one of the two hook bases and a second transmission rod parallelly spaced from the first transmission rod. A second screw rod unit is provided between the second movable block and the second transmission rod and is capable of converting a rotational motion into a linear motion. A conversion unit capable of converting a rotational direction into another rotational direction is provided between the second transmission rod and the first transmission rod. Whereby, when the first transmission rod rotates in the first rotational direction, the conversion unit enables the second transmission rod to rotate in a second rotational direction opposite to the first rotational direction, bringing the first movable block and the second movable block to move in two opposite directions.
In the above two embodiments, the double needle distance driving mechanism is configured for the adjustment stem to rotate while the needle bar is moving upward and downward; and a sewing head rotating mechanism is mounted ton the sewing head, which is capable of generating a rotating power for bringing the sewing head to rotate, such that the double needle distance adjusting mechanism and the double needle distance driving mechanism rotate synchronously with the sewing head. The sewing machine further includes a freely rotatable movable seat and a hook base driving mechanism mounted on the movable seat and capable of generating a rotating power. The two hook bases, the shuttle driving mechanism and the needle hole distance driving mechanism are connected to the movable seat. Via the movable seat, the hook base driving mechanism is able to bring the two hook bases, the shuttle driving mechanism and the needle hole distance driving mechanism to rotate synchronously.
However, the double needle distance driving mechanism includes a double needle distance driving source distant from the needle bar, and a double needle distance transmission unit connected to the double needle distance driving source. A double needle distance synchronizing unit located between the double needle distance transmission unit and the adjustment stem. The double needle distance synchronizing unit enables the adjustment stem to move axially relative to the double needle distance transmission unit and is capable of bringing the double needle distance transmission unit and the adjustment stem to rotate synchronously. In the preferred embodiment, the double needle distance synchronizing unit includes a double needle distance synchronizing channel, which is selectively formed on one of the double needle distance transmission unit and the adjustment stem, and a double needle distance synchronizing protrusion, which is selectively formed on the other one of the double needle distance transmission unit and the adjustment stem and is sidewardly extended into the double needle distance synchronizing channel. Whereby, the double needle distance synchronizing protrusion is movable upwardly and downwardly reciprocatingly in the double needle distance synchronizing channel when the adjustment stem is moving upwardly and downwardly.
Further, the shuttle driving mechanism includes a rotatable shuttle rotating shaft. A shuttle synchronizing unit is provided between the shuttle rotating shaft and the hook bases for the hook bases to move relative to the shuttle rotating shaft. The shuttle synchronizing unit also enables the shuttles and the shuttle rotating shaft to rotate synchronously. In the preferred embodiment, the shuttle synchronizing unit includes a spline shaft and a spline sleeve; one of which is formed on the shuttle rotating shaft while the other one is formed on a corresponding one of the two hook bases. The spline shaft is located in the spline sleeve, so that an axial relative position between the spine shaft and the spline sleeve changes whenever the corresponding hook base moves.
The sewing machine of the present invention is characterized in the adjustment unit provided between the needle bar and the two needles for converting the rotational motion into the linear motion, so that at least one of the two needles is movable sidewardly to change the distance between the two needles when the double needle distance driving mechanism brings the adjustment stem to rotate. With this arrangement, the double needle distance driving mechanism can change the distance between the two needles, enabling the sewing machine of the present invention to perform sewing operation on workpieces requiring different double needle distances without the need of replacing the needle holder manually, which in turn enables upgraded production efficiency of the sewing machine and saves the time and labor for replacing the needle holder and needle plate manually.
Further, the sewing machine of the present invention is also characterized in the double needle distance synchronizing unit provided between the double needle distance transmission unit and the needle bar. The double needle distance synchronizing unit enables the adjustment stem to move relative to the double needle distance transmission unit and ensures these two components to rotate synchronously. In this way, the adjustment stem is able to rotate while the needle bar moves upwardly and downwardly, enabling the distance between the two needles to change. Thus, two sewing lines with variable widths can be formed on the same workpiece using the sewing machine.
In addition, the sewing head is rotatable by the sewing head rotating mechanism. In the course of forming two sewing lines on the workpiece using the sewing machine with adjustable double needle distance, the sewing head can be rotated by the sewing head rotating mechanism while the double needle distance driving mechanism enables the adjustment stem to rotate and accordingly changes the distance between the two needles. Thus, the distance and the angular position of the two needles relative to each other are freely controllable in the course of sewing.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

Fig. 1A is a perspective view of a conventional double needle rotatable head pattern sewing machine;
Fig. 1B shows two needles of the conventional double needle sewing machine are connected to a needle bar via a needle holder;
Fig. 2 is a perspective view of a sewing machine with adjustable double needle distance according to a first embodiment of the present invention;
Fig. 3 is a perspective view showing a sewing head rotating mechanism, a double needle distance adjusting mechanism and a double needle distance driving mechanism mounted on a sewing head of the sewing machine of Fig. 2;
Fig. 4 is a perspective view showing a needle bar driving unit, a needle bar unit and an inner presser foot unit located in the sewing head of the sewing machine of Fig. 2;
Fig. 5A is a perspective view showing the mounting of the double needle distance adjusting mechanism on the needle bar unit;
Fig. 5B is an exploded view of Fig. 5A;
Fig. 6 is a perspective view showing the mounting of the double needle distance driving mechanism on a needle bar of the needle bar unit;
Fig. 7A shows an adjustment stem of the double needle distance adjusting mechanism is brought by the needle bar to move upward and downward;
Fig. 7B shows a double needle distance synchronizing protrusion is reciprocatingly movable in a double needle distance synchronizing channel of the double needle distance driving mechanism;
Figs. 8A and 8B show the manner of increasing the double needle distance;
Figs. 8C and 8D show the manner of decreasing the double needle distance;
Fig. 9 is a perspective view showing the mounting of a hook base driving mechanism, a shuttle driving mechanism and a needle hole distance driving mechanism on a movable seat of the sewing machine of Fig. 2;
Fig. 10 shows two hook bases located in the movable seat;
Fig. 11 is an exploded perspective view of the shuttle driving mechanism;
Fig. 12 is a cutaway view showing a first shuttle synchronizing unit of the shuttle driving mechanism;
Fig. 13 is a perspective view of the needle hole distance driving mechanism;
Fig. 14 is a perspective view showing a first shuttle and a second shuttle in rotating;
Figs. 15A to 15C show the manner of increasing the needle hole distance;
Figs. 15D to 15F show the manner of decreasing the needle hole distance;
Fig. 16 is an exploded perspective view showing the assembling of the double needle distance adjusting mechanism to the needle bar unit according to a second embodiment of the present invention;
Fig. 17A shows two racks of the double needle distance adjusting mechanism in the second embodiment of the present invention are moved at the same time to increase the double needle distance;
Fig. 17B shows the two racks of the double needle distance adjusting mechanism in the second embodiment of the present invention are moved at the same time to decrease the double needle distance;
Fig. 18 is a cutaway view showing a second shuttle synchronizing unit of the shuttle driving mechanism in the second embodiment of the present invention;
Fig. 19 is a perspective view of the needle hole distance driving mechanism in the second embodiment of the present invention;
Figs. 20A to 20C show the manner of increasing the needle hole distance in the second embodiment of the present invention;
Figs. 20D to 20F show the manner of decreasing the needle hole distance in the second embodiment of the present invention; and
Fig. 21 shows the assembling of the double needle distance driving mechanism to the adjustment stem of the double needle distance adjusting mechanism according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with some preferred embodiments thereof and by referring to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.
Please refer to Fig. 2 that is a perspective view of a sewing machine with adjustable double needle distance according to a first embodiment of the present invention, which is also briefly referred to as the sewing machine and generally denoted by reference numeral 1 herein. As shown, the sewing machine 1 has a main body 10, which includes a sewing head 11, a pillar 12 and a base 13. Please also refer to Figs. 3 and 4. A needle bar driving unit 14, a needle bar unit 15 and an inner presser foot unit 16 are mounted in the sewing head 11 as shown in Fig. 4; and a sewing head rotating mechanism 20, a double needle distance adjusting mechanism 30 and a double needle distance driving mechanism 40 are mounted on the sewing head 11 as shown in Fig. 3. Wherein, the double needle distance adjusting mechanism 30 can be more clearly seen in Figs. 5A and 5B.
Please refer to Fig. 4 along with Fig. 3. The needle bar driving unit 14 includes a needle bar driving source 141 fixed to the sewing head 11 and an upper shaft 142 rotatable relative to the sewing head 11. The needle bar driving source 141 is assembled to a first needle bar belt pulley 143, which is located outside the sewing head 11 and has a needle bar transmission belt 144 wound therearound to therefore connect the first needle bar belt pulley 143 to a second needle bar belt pulley 145, which is mounted on the upper shaft 142. Via the first needle bar belt pulley 143, the needle bar transmission belt 144 and the second needle bar belt pulley 145, the first needle bar driving source 141 can drive the upper shaft 142 to rotate. And, an end of the upper shaft 142 opposite to the second needle bar belt pulley 145 is provided with a crankshaft linkage 146 for connecting to the needle bar unit 15.
Please refer to refer to Fig. 4 and Figs. 5A and 5B. The needle bar unit 15 includes a vertically arranged needle bar 151, which is a hollow element and connected to the crankshaft linkage 146 of the needle bar driving mechanism 14, so that the upper shaft 142 of the needle bar driving unit 14 drives the needle bar 151 to move upward and downward when the latter is driven to rotate by the needle bar driving source 141. A needle base 152 is mounted to a lower end of the needle bar 151, and two parallelly spaced needles 153 are provided at one side of the needle base 152 opposite to the needle bar 151. As shown in Fig. 4, one of the two needles 153 is referred to as the first needle 153a, while the other one is referred to as the second needle 153b. In the illustrated first embodiment, as shown in Fig. 5B, the first needle 153a is upward extended into an elongated slot 152a formed on the needle base 152 with an axis of the first needle 153a spaced from an axis of the needle bar 151. Further, the first needle 153a is displaceable relative to the needle base 152, while the second needle 153b is fixed to the needle base 152 without being displaceable relative thereto. On the other hand, as shown in Fig. 4, the inner presser foot unit 16 includes an inner presser foot 161 arranged in parallel to the needle bar 151, and an inner presser foot transmission unit 162 for connecting the inner presser foot 161 to the upper shaft 142, so that the inner presser foot transmission unit 162 brings the inner presser foot 161 to move upward and downward when the upper shaft 142 is driven to rotate by the needle bar driving source 141.
Please refer to Figs. 2 and 3. The sewing head 11 is connected to the pillar 12 via the sewing head rotating mechanism 20, which includes a sewing head gearbox 21 fixed to the pillar 12, a sewing head driving source 22 assembled to the gearbox 21, and a hollow sewing head rotating column 23 for connecting the sewing head gearbox 21 to a top of the sewing head 11. Via the gearbox 21, the sewing head driving source 22 can bring the sewing head 11 to rotate about the axis of the needle bar 151, so that the sewing head 11 is rotatable relative to the pillar 12. When the sewing head 11 is rotating, the needle bar 15, the double needle distance adjusting mechanism 30 and the double needle distance driving mechanism 40 all are rotated synchronously with the sewing head 11.
Please refer to Figs. 5A and 5B. The double needle distance adjusting mechanism 30 includes a vertically arranged adjustment stem 31 and an adjustment unit 32 connected to the adjustment stem 31. The adjustment stem 31 is rotatably axially extended through the needle bar 151 of the needle bar unit 15 and the adjustment unit 32 is arranged on the needle base 152 of the needle bar unit 15, such that the double needle distance adjusting mechanism 30 is located between the adjustment stem 31 and the two needles 153 of the needle bar unit 15. In the illustrated first embodiment, the adjustment unit 32 functions to convert a rotational motion into a linear motion and includes a gear 321 fixed to a lower end of the adjustment stem 31 and a first rack 322 engaged with the gear 321. The gear 321 and the first rack 322 all are located in the needle base 152. The gear 321 has an outer diameter larger than a bore size of the hollow needle bar 151; and the first rack 322 is extended across the needle bar 151 and connected to the first needle 153a of the needle bar unit 15.
Please refer to Fig. 6. The double needle distance driving mechanism 40 includes a double needle driving source 41 capable of generating a rotating power and a double needle distance transmission unit 42 connected to the double needle distance driving source 41. The double needle distance driving source 41 is fixedly connected to the sewing head 11 of the main body 10 at a position distant from the needle bar 151 of the needle bar unit 15. The double needle distance transmission unit 42 includes a first double needle distance belt pulley 421 connected to the double needle distance driving source 41, and a second double needle distance belt pulley 422 fitted around the adjustment stem 31 of the double needle distance adjusting mechanism 30. The first double needle distance belt pulley 421 is connected to an intermediate pulley assembly 424 via a first double needle distance transmission belt 423. A connecting seat 425 is mounted on the second double needle distance belt pulley 422 to be located below the sewing head rotating column 23. The second double needle distance belt pulley 422 is connected to the intermediate pulley 424 via a second double needle distance transmission belt 426. As shown in Fig. 6, a double needle distance synchronizing unit 427 is provided between the connecting seat 425 and the adjustment stem 31 of the double needle distance adjusting mechanism 30 for the adjustment stem 31 to move upward and downward relative to the second double needle distance belt pulley 422. In the illustrated first embodiment, the double needle distance synchronizing unit 427 also functions for the second double needle distance belt pulley 422 and the adjustment stem 31 to rotate synchronously.
As can be seen in Fig. 6, the double needle distance synchronizing unit 427 includes a double needle distance synchronizing channel 427a, which is formed on the connecting seat 425 of the double needle distance transmission unit 42 and arranged in parallel with the adjustment stem 31 of the double needle distance adjusting mechanism 30, and a double needle distance synchronizing protrusion 427b, which is in the form of a roller connected to a side surface of the adjustment stem 31. The double needle distance synchronizing protrusion 427b is projected into and in line contact with an inner wall surface of the double needle distance synchronizing channel 427a. However, it is understood the forming of the double needle distance synchronizing channel 427a on the connecting seat 425 and the forming of the double needle distance synchronizing protrusion 427b on the adjustment stem 31 are only illustrative for easy description of the present invention. In other operable embodiments, a portion of the adjustment stem 31 can be provided with a groove to form the double needle distance synchronizing channel 427a and a roller can be mounted on the connecting seat 425 to form the double needle distance synchronizing protrusion 427b.
Please refer to Figs. 7A and 7B. When perform a sewing operation on the sewing machine 1, the needle bar driving source 41 of the needle bar driving mechanism 40 brings the upper shaft 142 to rotate. Via the crankshaft linkage 146, the rotating upper shaft 142 brings the needle bar 15 of the needle bar unit 15 to move upward and downward. In the meantime, the needle base 152 of the needle bar unit 15 restricts the gear 321 of the adjustment unit 32 (see Fig. 5B) from displacing upward and downward. With these arrangements, the adjustment stem 31 will move upward and downward synchronously with the needle bar 151. On the other hand, when the adjustment stem 31 moves upward and downward, the double needle distance synchronizing unit 427 of the double needle distance driving mechanism 40 provided between the connecting seat 425 and the adjustment stem 31 allows the adjustment stem 31 to move upward and downward relative to the second double needle distance belt pulley 422 of the double needle distance transmission unit 42. Meanwhile, via the needle base 152 of the needle bar unit 15 and the adjustment unit 32 of the double needle distance adjusting mechanism 30 (see Fig. 5B), the needle bar 151 brings the two needles 15 of the needle bar unit 15 to move upward and downward. Further, during the moving course of the adjustment stem 31, the double needle distance synchronizing protrusion 427b is moving upward and downward in the double needle distance synchronizing channel 427a, so that a position of the double needle distance synchronizing protrusion 427b relative to the double needle distance synchronizing channel 427a is always changeable.
Please refer to Figs. 8A and 8B. To adjust the distance between the two needles 153 on the sewing machine 1, actuate the double needle distance driving source 41 of the double needle distance driving mechanism 40, so that the first double needle distance belt pulley 421 of the double needle distance transmission unit 42 starts rotating. Via the first double needle distance transmission belt 423, the intermediate pulley 424 and the second double needle distance transmission belt 426, the rotational power of the first double needle distance belt pulley 421 is transferred to the second double needle distance belt pulley 422, bringing the latter to rotate. In the meantime, via the double needle distance synchronizing unit 427 that has the double needle distance synchronizing protrusion 427b extended into the double needle distance synchronizing channel 427a, the second double needle distance belt pulley 422 brings the adjustment stem 31 of the double needle distance adjusting mechanism 30 to rotate counterclockwise relative to the needle bar 151. At this point, the gear 321 of the double needle distance adjusting mechanism 30 is caused to rotate counterclockwise about the axis of the needle bar 151, which brings the first rack 322 of the double needle distance adjusting mechanism 30 to sidewardly and linearly move in a first direction F1 parallel with the upper shaft 142, so that the first needle 153a is moved farther away from the second needle 153b of the needle bar unit 15 to increase the distance between the two needles 153. Please refer to Figs. 8C and 8D. Reversely, when the adjustment stem 31 is brought by the double needle distance driving source 41 to rotate clockwise, the gear 321 rotates clockwise about the needle bar 151 and brings the first rack 322 to sidewardly and linearly move in a second direction F2 opposite to the first direction F1, so that the first needle 153a is moved closer to the second needle 153b to decrease the distance between the two needles 153. In this way, during the course the needle bar 151 is brought by the upper shaft 142 to move upward and downward, the double needle distance driving source 41 is able to rotate the adjustment stem 31 at any time. In the illustrated first embodiment, when the needle bar 151 is moving while rotating, the sewing head rotating mechanism 20 can bring the sewing head 11 of the main body 10 to rotate at the same time.
Please refer back to Fig. 2. The pillar 12 of the main body 10 is connected to the base 13. A movable seat 17 is provided at an end of the base 13 farther away from the pillar 12. The movable seat 17 is internally provided with two hook bases 18, and is externally connected to a hook base driving mechanism 50, a shuttle driving mechanism 60 and a needle hole distance driving mechanism 70. Please refer to Figs. 9 and 10. One of the two hook bases 18 is referred to as the first hook base 181, which is movably mounted on the movable seat 17, and the other one is referred to as the second hook base 182, which is fixedly mounted on the movable seat 17. The first hook base 181 includes a first connecting bracket 181a movably connected to the movable seat 17 and a first needle plate 181b assembled to the first connecting bracket. The first connecting bracket 181a is pivotally connected to a vertically arranged first shuttle shaft 181c, an upper end of which is connected to a first shuttle 181d located between the first connecting bracket 181a and the first needle plate 181b. The first shuttle shaft 181c is connected at another end to a first bevel gear set 181e. The first needle plate 181b is located above the first connecting bracket 181a and is exposed from the movable seat 17. The first needle plate 181b is formed with a first needle hole 181b1, which is located in alignment with the first needle 153a. In the illustrated first embodiment, the second hook base 182 includes a second connecting bracket 182a, a second needle plate 182b, a second shuttle shaft 182c, a second shuttle 182d and a second bevel gear set 182e. The second hook base 182 is structurally similar to the first hook base 181, such that the second connecting bracket 182a, the second needle plate 182b, the second shuttle shaft 182c, the second shuttle 182d and the second bevel gear set 182e are connected to one another in the same way as the corresponding components in the first hook base 181. Wherein, like the first needle plate 181b, the second needle plate 182b is also exposed from the movable seat 17 and is formed with a second needle hole 182b1 located in alignment with the second needle 153b.
Please refer to Fig. 9. The movable seat 17 is connected to the base 13 via a hook base driving mechanism 50, which includes a bottom gearbox 51 fixed to the hook base 18, and a hook base driving source 52 assembled to the bottom gearbox 51. As shown, a hook base rotating column 53 is located above the bottom gearbox 51 to connect to the movable seat 17. Via the bottom gearbox 51, the hook base driving source 52 brings the movable seat 17 to rotate about the hook base rotating column 53, such that the movable seat 17 is rotatable relative to the base 13. When the movable seat 17 is rotating, the shuttle driving mechanism 60 and the needle hole distance driving mechanism 70 also rotate synchronously with the sewing head 11. In the illustrated first embodiment, when the sewing head 11 of the main body 10 of the sewing machine 1 is rotating, the hook base driving mechanism 50 will bring the movable seat 17 to rotate synchronously.
Please refer to Fig. 11. The shuttle driving mechanism 60 includes a shuttle driving source 61 fixed to the movable seat 17 and capable of generating a rotating power, and a shuttle transmission unit 62 assembled to the shuttle driving source 61 and including a first shuttle belt pulley 621 connected to the shuttle driving source 61 and a second shuttle belt pulley 622 pivotally connected to the movable seat 17. A shuttle transmission belt 623 is mounted on the first and the second shuttle belt pulley 621, 622. A horizontally arranged shuttle rotating shaft 624 is mounted on the second shuttle belt pulley 622 to extend through a first extending bore 181e1 formed at the first bevel gear set 181e and a second extending bore 182e1 formed at the second bevel gear set 182e.
Please refer to Fig. 12. A first shuttle synchronizing unit 625 is provided between the shuttle rotating shaft 624 of the shuttle driving mechanism 60 and the first bevel gear set 181e of the first hook base 181, such that the first hook base 181 can move relative to an axial direction of the shuttle rotating shaft 624. In the illustrated first embodiment, the first shuttle synchronizing unit 625 can also cause the shuttle rotating shaft 624 and the first shuttle 181d of the first hook base 181 to rotate synchronously. As shown, the first shuttle synchronizing unit 625 includes a first spline sleeve 625a and a first spline shaft 625b. The first spline sleeve 625a is formed in the first extending bore 181e1 of the first bevel gear set 181e; and the first spline shaft 625b is externally formed on around the shuttle rotating shaft 624.
Please refer to Fig. 13 along with Figs. 9 and 10. The needle hole distance driving mechanism 70 includes a needle hole distance driving source 71 capable of generating a rotating power and a needle hole distance transmission unit 72 connected to the needle hole distance driving source 71. The needle hole distance driving source 71 is located farther away from the shuttle driving source 61 of the shuttle driving mechanism 60 and connected to the movable seat 17, such that the needle hole distance driving source 71 and the shuttle driving source 61 are separately located at two opposite ends of the movable seat 17. The needle hole distance transmission unit 72 includes a first needle hole distance belt pulley 721 connected to the needle hole distance driving source 71 and a second needle hole distance belt pulley 722 pivotally connected to the movable seat 17. The first needle hole distance belt pulley 721 is connected to the second needle hole distance belt pulley 722 via a needle hole distance transmission belt 723. The second needle hole distance belt pulley 722 is connected to a horizontally arranged first transmission rod 724, which is parallel with the shuttle rotating shaft 624 of the shuttle driving mechanism 60 and extended through a first movable block 725 connected to the first hook base 181. As shown in Fig. 15B, a first screw rod unit 726 capable of converting a rotating motion into a linear motion is provided between the first transmission rod 724 and the first movable block 725. In the illustrated first embodiment, the first screw rod unit 726 includes a first male thread 726a formed on the first transmission rod 724 and a first female thread 726b for engaging with the first male thread 726a. The first female thread 726b is provided in a first inner bore 725a, which is axially extended through the first movable block 725.
Please refer to Fig. 14. When the needle bar 151 of the needle bar unit 15 is moved upward and downward, the shuttle driving source 61 of the shuttle driving mechanism 60 rotates at the same time and brings the first shuttle belt pulley 621 of the shuttle transmission unit 62 to rotate. Via the shuttle transmission belt 623, the first shuttle belt pulley 621 transfers a rotating power to the second shuttle belt pulley 622. Due to the first spline shaft 625b of the first shuttle synchronizing unit 625 that is internally extended through the first spline sleeve 625a, the shuttle rotating shaft 624 connected to the rotating second shuttle belt pulley 622 can, via the first bevel gear set 181e of the first hook base 181, bring the first shuttle 181d to rotate about the first shuttle shaft 181c. And, when the first shuttle 181d rotates, the shuttle rotating shaft 624 also, via the second bevel gear set 182e of the second hook base 182, brings the second shuttle 182d to rotate about the second shuttle shaft 182c in the same direction as the first shuttle 181d.
Please refer to Figs. 15A, 15B and 15C. To adjust the distance between the first and the second needle hole 181b1, 182b1 of the sewing machine 1, actuate the needle hole distance driving source 71 of the needle hole distance driving mechanism 70 for the first needle hole distance transmission belt pulley 721 of the needle hole distance transmission unit 72 to rotate counterclockwise. Via the needle hole distance transmission belt 723, the first needle hole distance transmission pulley 721 transfer a counterclockwise rotating power to the second needle hole distance transmission belt pulley 722, which further causes the first transmission rod 724 of the needle hole distance transmission unit 72 to rotate about its own axis in a first rotational direction F3. At this point, due to the first screw rod unit 726, the first movable block 725 of the needle hole distance transmission unit 72 is brought to move in the first direction F1, which causes the first hook base 181 to move farther away from the second hook base 182, such that the distance between the first and the second needle hole 181b1, 182b1 is increased. On the other hand, as shown in Figs. 15D, 15E and 15F, when the needle hole distance transmission unit 72 enables the needle hole distance driving source 71 to rotate the first transmission rod 724 in a second rotational direction F4 opposite to the first rotational direction F3, the first screw rod unit 726 enables the first movable block 725 to move in the second direction F2, which causes the first hook base 181 to move closer to the second hook base 182, such that the distance between the first and the second needle hole 181b1, 182b1 is decreased.
In the illustrated first embodiment, when the shuttle driving mechanism 60 rotates the first shuttle 181d of the first hook base 181 and the second shuttle 182d of the second hook base 182, the first shuttle synchronizing unit 625 enables the needle hole distance driving mechanism 70 to move the first hook base 181 at the same time, so as to change the distance between the first and the second needle hole 181b1, 182b1. Thus, when the first shuttle 181d moves while rotating, the hook base driving mechanism 50 can bring the movable seat 17 of the sewing machine main body 10 to rotate.
The sewing machine 1 according to a second embodiment of the present invention is generally structurally similar to the first embodiment, except for the needle bar unit 15 on the main body 10, the second hook base 182 on the base 13, the double needle distance adjusting mechanism 30, the shuttle driving mechanism 60 and the needle hole distance driving mechanism 70. The parts of the second embodiment that are similar to the first embodiment are not repeatedly described herein. Please refer to Fig. 16. In the needle bar unit 15 of the second embodiment, like the first needle 153a, the second needle 153b is also extended into the elongated slot 152a of the needle base 152. The double needle distance adjusting mechanism 30 of the second embodiment further includes a second rack 323, which together with the gear 321 and the first rack 322 forms the adjustment unit 32. As shown, the second rack 323 is engaged with the gear 321 and connected to the second needle 153b. In the second embodiment, the first and the second rack 322, 323 are separately located at two opposite sides of the gear 321; and the first and the second needle 153a, 153b are symmetrically arranged at two opposite ends relative to the axis of the needle bar 151.
Please refer to Fig. 17A. To adjust the distance between the two needles 153 of the sewing machine 1 according to the second embodiment, actuate the double needle distance driving source 41 of the double needle distance driving mechanism 40 for the double needle distance transmission unit 42 to counterclockwise rotate the adjustment stem 31 of the double needle distance adjusting mechanism 30, which in turn causes the gear 321 of the double needle distance adjusting mechanism 30 to rotate counterclockwise simultaneously about the axis of the needle bar 151. Thus, the first rack 322 is brought to sidewardly linearly move in the first direction F1 and the second rack 323 is brought to sidewardly and linearly move in the second direction F2 at the same time, which causes the first and the second needle 153a, 153b to move simultaneously but in two opposed directions and accordingly, increases the distance between the first and the second needle 153a, 153b. On the other hand, as shown in Fig. 17B, when the double needle distance driving source 41 clockwise rotates the needle bar 151, the gear 321 brings the first rack 322 to sidewardly and linearly move in the second direction F2 and the second rack 323 to sidewardly and linearly move in the first direction F1 at the same time, causing the first needle 153a and the second needle 153b to move closer to each other and have a decreased distance between them.
Please refer to Fig. 18. The shuttle driving mechanism 60 in the second embodiment of the present invention further includes a second shuttle synchronizing unit 626, which is functionally similar to the first shuttle synchronizing unit 625 and is arranged between the shuttle rotating shaft 624 and the second bevel gear set 182e of the second hook base 182. The second shuttle synchronizing unit 626 enables the second hook base 182 to move relative to the shuttle rotating shaft 624, which in turn enables the second hook base 182 to move relative to the movable seat 17. In the illustrated second embodiment, since the first and the second shuttle synchronizing unit 625, 626 are the same in function, the second shuttle synchronizing unit 626 can also enable the shuttle rotating shaft 624 and the second shuttle 182d of the second hook base 182 to rotate synchronously. As shown, the second shuttle synchronizing unit 626 includes a second spline sleeve 626a and a second spline shaft 626b. The second spline sleeve 626a is formed in the second extending bore 182e1 of the second bevel gear set 182e; and the second spline shaft 626b is externally formed on around the shuttle rotating shaft 624.
Please refer to Fig. 19. The first transmission rod 724 of the needle hole distance driving mechanism 70 according to the second embodiment has a conversion unit 727 assembled thereto for converting a rotational direction into another rotational direction. The conversion unit 727 includes a first converting gear 727a mounted on the first transmission rod 724 and a second converting gear 727b engaged with the first converting gear 727a and mounted on a second transmission rod 728, which is parallel with the first transmission rod 724 and extended through a second movable block 729 connected to the second hook base 182. As shown in Fig. 20B, a second screw rod unit 730 functionally similar to the first screw rod unit 726 and capable of converting a rotating motion into a linear motion is provided between the second transmission rod 728 and the second movable block 729. The second screw rod unit 730 includes a second male thread 730a formed on around the second transmission rod 728 and a second female thread 730b engaged with the second male thread 730a. The second female thread 730b is provided in a second inner bore 729a, which is axially extended through the second movable block 729.
Please refer to Figs. 20A, 20B and 20C. To adjust the distance between the first needle hole 181b1 and the second needle hole 182b1 of the sewing machine 1, actuate the needle hole distance driving source 71 of the needle hole distance driving mechanism 70 to rotate the first transmission rod 724 of the needle hole distance transmission unit 72 in the first rotational direction F3. In the meantime, the conversion unit 727 causes the second transmission rod 728 of the needle hole distance transmission unit 72 to rotate in the second rotational direction F4, such that the first transmission rod 724 and the second transmission rod 728 rotate in two opposite directions. Due to the first screw rod unit 726, the first movable block 725 of the needle hole distance transmission unit 72 is caused to move in the first direction F1, which further enables the first hook base 181 to move the first needle plate 181b in the direction F1. Similarly, due to the second screw rod unit 730, the second movable block 729 of the needle hole distance transmission unit 72 is caused to move in the second direction F2, which further enables the second hook base 182 to move the second needle plate 182b in the second direction F2. Thus, the distance between the first needle hole 181b1 and the second needle hole 182b1 is increased. On the other hand, as shown in Figs. 20D, 20E and 20F, when the needle hole distance driving source 71 brings the first transmission rod 724 to rotate in the second rotational direction F4, the conversion unit 727 also enables the second transmission rod 728 to rotate in the first rotational direction F3, such that the first movable block 725 brings the first hook base 181 to move in the second direction F2 while the second movable block 729 brings the second hook base 182 to move in the first direction F1. Thus, the distance between the first needle hole 181b1 and the second needle hole 182b1 is decreased.
Please refer to Fig. 21, which shows a double needle distance driving mechanism 40 in the sewing machine 1 according to a third embodiment of the present invention. The third embodiment is structurally similar to the first embodiment, except for the double needle distance driving mechanism 40. In the illustrated third embodiment, the double needle distance driving mechanism 40 includes only the axially slidable double needle distance synchronizing unit 427 and a double needle distance driving source 41 connected to the former. The double needle distance driving source 41 is directly mounted above the axis of the adjustment stem 31 to rotate the latter. With this arrangement, the double needle distance driving source 41 can bring the adjustment stem 31 to rotate while the needle bar driving source 141 of the needle bar driving unit 14 brings the needle bar 151 to move upward and downward.

Claims

A sewing machine (1) with adjustable double needle distance, comprising:
a sewing head (11) including an upper shaft (142) and a needle bar (151); the upper shaft (142) being rotatable to bring the needle bar (151) to move upward and downward, such that two needles (153) located at a lower end of the needle bar (151) move synchronously with the needle bar (151);

a double needle distance driving mechanism (40); and

a double needle distance adjusting mechanism (30) including an adjustment stem (31) axially extended through the needle bar (151) and an adjustment unit (32) located between the adjustment stem (31) and the two needles (153); the adjustment stem (31) being brought by the double needle distance driving mechanism (40) to rotate, and the adjustment stem (31) in rotating enabling the adjustment unit (32) to cause at least one of the two needles (153) to move sidewardly, so that the two needles (153) are located closer to or farther away from each other;

characterized in that the adjustment unit (32) includes a gear (321) connected to the adjustment stem (31) and a first rack (322) connected to a first one of the two needles (153); the gear (321) being brought by the adjustment stem (31) to rotate; and the first rack (322) being engaged with the gear (321), so that the first one of the two needles (153) is moved sidewardly in a first direction (F1) across the needle bar (151) by the first rack (322).
The sewing machine (1) with adjustable double needle distance as claimed in claim 1, wherein the double needle distance driving mechanism (40) is configured for the adjustment stem (31) to rotate while the needle bar (151) is moving upward and downward.
The sewing machine (1) with adjustable double needle distance as claimed in claim 1, wherein a sewing head rotating mechanism (20) is mounted on the sewing head (11); the sewing head rotating mechanism (20) being capable of generating a rotating power for bringing the sewing head (11) to rotate, such that the double needle distance adjusting mechanism (30) and the double needle distance driving mechanism (40) rotate synchronously with the sewing head (11).
The sewing machine (1) with adjustable double needle distance as claimed in claim 1, wherein one side of the gear (321) opposite to the first rack (322) is engaged with a second rack (323), and the second rack (323) is connected to a second one of the two needles (153); whereby, the second rack (323) brings the second one of the two needles (153) to move sidewardly in a second direction (F2) opposite to the first direction (F1) when the gear (321) rotates and the first rack (322) brings the first needle to sidewardly move in the first direction (F1).
The sewing machine (1) with adjustable double needle distance as claimed in claim 1, wherein the double needle distance driving mechanism (40) includes a double needle distance driving source (41) distant from the needle bar (151), a double needle distance transmission unit (42) connected to the double needle distance driving source (41), and a double needle distance synchronizing unit (427) located between the double needle distance transmission unit (42) and the adjustment stem (31); and the double needle distance synchronizing unit (427) enabling the adjustment stem (31) to move axially relative to the double needle distance transmission unit (42) and being capable of bringing the double needle distance transmission unit (42) and the adjustment stem (31) to rotate synchronously.
The sewing machine (1) with adjustable double needle distance as claimed in claim 5, wherein the double needle distance synchronizing unit (427) includes a double needle distance synchronizing channel (427a), which is selectively formed on one of the double needle distance transmission unit (42) and the adjustment stem (31), and a double needle distance synchronizing protrusion (427b), which is selectively formed on the other one of the double needle distance transmission unit (42) and the adjustment stem (31) and is sidewardly extended into the double needle distance synchronizing channel (427a); whereby, the double needle distance synchronizing protrusion (427b) is movable upwardly and downwardly in the double needle distance synchronizing channel (427a) when the adjustment stem (31) is moving upwardly and downwardly.
The sewing machine (1) with adjustable double needle distance as claimed in claim 1, further comprising:
two hook bases (18, 181, 182), each of which including a rotatable shuttle (181d, 182d) and a needle plate (181b, 182b) located above the shuttle (181d, 182d); and each of the needle plates (181b, 182b) having a needle hole (181b1, 182b1) aligned with one of the two needles (153);

a shuttle driving mechanism (60) capable of bringing the shuttles (181d, 182d) on the two hook bases (18, 181, 182) to rotate simultaneously; and

a needle hole distance driving mechanism (70) capable of synchronously bringing at least one of the two hook bases (18, 181, 182) to move in the first direction (F1) when the two needles (153) are moved closer to or farther away from each other, so that a distance between the two needle holes (181b1, 182b1) is the same as a distance between the two needles (153).
The sewing machine (1) with adjustable double needle distance as claimed in claim 7, further comprising a freely rotatable movable seat (17), to which the two hook bases (18, 181, 182), the shuttle driving mechanism (60) and the needle hole distance driving mechanism (70) are connected, and a hook base driving mechanism (50) mounted on the movable seat (17) and capable of generating a rotating power; and, via the movable seat (17), the hook base driving mechanism (50) being able to bring the two hook bases (18, 181, 182), the shuttle driving mechanism (60) and the needle hole distance driving mechanism (70) to rotate synchronously.
The sewing machine (1) with adjustable double needle distance as claimed in claim 7, wherein the needle hole distance driving mechanism (70) includes a displaceable first movable block (725) and a rotatable first transmission rod (724); the first movable block (725) being connected to a first one of the two hook bases (18, 181, 182); and a first screw rod unit (726) being provided between the first movable block (725) and the first transmission rod (724) and being capable of converting a rotational motion into a linear motion; whereby, when the first transmission rod (724) rotates in a first rotational direction (F3), the first screw rod unit (726) enables the first movable block (725) to bring the first one of the hook bases (18, 181, 182) to move.
The sewing machine (1) with adjustable double needle distance as claimed in claim 9, wherein the needle hole distance driving mechanism (70) further includes a second movable block (729) connected to the second one of the two hook bases (18, 181, 182) and a second transmission rod (728) parallelly spaced from the first transmission rod (724); a second screw rod unit (730) being provided between the second movable block (729) and the second transmission rod (728) and being capable of converting a rotational motion into a linear motion; and a conversion unit (727) capable of converting a rotational direction into another rotational direction being provided between the second transmission rod (728) and the first transmission rod (724); whereby, when the first transmission rod (724) rotates in the first rotational direction (F3), the conversion unit (727) enables the second transmission rod (728) to rotate in a second rotational direction (F4) opposite to the first rotational direction (F3), bringing the first movable block (725) and the second movable block (729) to move in two opposite directions.