Title of Invention	"A MULTI-HEAD EMBROIDERY MACHINE"
Abstract	The present invention provides a multi-head embroidery machine, in which 21 to 70 units of sewing machine heads, each including arranged 3 to 15 needles, are arranged in a line on a machine frame at a head center pitch of 135 to 400 mm, and a main spindle common to all the sewing machine heads is driven by two motors connected to both end portions of the main spindle.

Full Text

MULTI-HEAD EMBROIDERY MACHINE TECHNICAL FIELD The present invention relates to a multi-head embroidery -machine including a plurality of sewing-machine heads arranged on a machine frame. BACKGROUND OF THE INVENTION In the aforementioned type of the embroidery machine, needle bars and take-up levers are driven by a main spindle common to all the sewing machine heads. Therefore, as the number of the sewing machine heads increases, the main spindle becomes long. The resultant twist of the thus elongated main spindle may vary the embroidery precision or cause noise and vibration. The art for suppressing the twist of the main spindle by changing the power transmission position of the main spindle drive motor has been proposed. For example, Japanese Patent Application Publication No. JP-A-8-243287 discloses the technology for transmitting the power of the single motor to the center portion of the main spindle and the technology for transmitting the power of two motors to both end portions of the main spindle. SUMMARY OF THE INVENTION However, as the aforementioned art focuses attention only on the power transmission position, the effect for suppressing the twist of the main spindle may be reduced if the number of the heads is increased and the main spindle becomes further longer. In such a case, a main spindle having a standard diameter cannot be used, and thus the use of the main spindle with larger diameter or the main spindle which only its proximal end portion have larger diameter (see Japanese Patent Application Publication No. JP-A-8-243287) is required. Furthermore, power transmission components such as a high-power motor, a large-diameter bearing, a large-sized pulley and belt, that are suitable for the aforementioned main spindle are required. In the case of developing the multi-head embroidery machine including more than 30 heads, for example, -the number of components -required to be newly-purchased—is-increased, resulting in the sharp increase in manufacturing costs. The obj ect of the present invention is to solve the problems described above and to provide a multi -head embroidery machine for allowing the increase in the number of sewing machine heads with a low cost structure while suppressing the twist of the main spindle using standard components. In a multi-head embroidery machine according to a first aspect of the present invention, 21 to 70 units of sewingmachine heads, each including arranged 3 to 15 needles, are arranged in a line on a machine frame at a head center pitch of 135 to 400 mm, and a main spindle common to all the sewing machine heads is driven by two motors connected to both end portions of the main spindle. In a multi-head embroidery machine according to a second aspect of the present invention, 11 to 30 units of sewingmachine heads, each including arranged 3 to 15 needles, are arranged in a line on a machine frame at a head center pitch of 160 to 400 mm, and a main spindle common to all the sewing machine heads is driven by a motor connected to a center portion of the main spindle. In a multi-head embroidery machine according to a third aspect of the present invention, 51 to 70 units of sewingmachine heads, each including arranged 3 to 15 needles, are arranged in a line on a machine frame at a head center pitch of 135 to 400 mm, and a main spindle common to all the sewing machine heads is driven by three motors connected to both end portions and a center portion of the main spindle. The head center pitch between adjacent sewing machine heads is determined based on the length of the main spindle which is obtained when the result of calculating the twist angle caused by rotating the main spindle with a standard diameter using the standard power motor under the load condition in -accordance with the number of heads—is—equal- to or smaller than the allowable value. According to the aforementioned calculation, as the number of the heads increases, the head center pitch is reduced. In this case, the number of motors in accordance with the number of the heads, and the power transmission position (the position for connecting the motor and the main spindle) may be considered for the calculation, so that the head center pitch suitablefor the practical use can be obtained. In the multi-head embroidery machine according to the present invention, the head center pitch of the sewing machine heads is set based on the number of the heads, the number of the motors, and the power transmission positions. Therefore, even if the number of the heads for the embroidery machine is increased, the entire length of the main spindle does not increase in accordance with the increased number of the sewing machine heads. As a result, standard components can be used to suppress the twist of the main spindle, thus increasing the number of the sewing machine heads with the structure formed at lower costs. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a multi-head embroidery machine according to a first embodiment of the present invention; FIG. 2 is a plan view showing a main spindle drive mechanism of the embroidery machine; FIG. 3 is a plan view showing the main spindle drive mechanism of the multi-head embroidery machine according to a second embodiment; FIG. 4 is a plan view showing the main spindle drive mechanism of the multi-head embroidery machine according to a third embodiment; and FIG. 5 is a plan view showing a modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION Embodiments according to the present invention will be described referring to the drawings. As shown in FIG. 1, a plurality of sewing machine heads 3 are arranged on a machine frame 2 of a multi-head embroidery machine 1. Needle bars 5 and take-up levers 6 of the respective heads 3 are driven by a main spindle 4 common to all the heads 3. Beds 7 are disposed below the corresponding sewing machine heads 3. A table 8 is provided at substantially the same height as that of the bed 7. A sewing frame 9 is provided on the table 8 for holding a working fabric so as to be movable both in longitudinal and lateral directions. A control panel 10 is disposed at a right end portion of the table 8, and a control panel 11 is further disposed below the table 8. The sewing machine head 3 is a multi-needle type head including 5 to 9 needles arranged, one of which is selectively set to a sewing position. The plurality of the sewing machine heads 3 is arranged in a transverse line on the machine frame 2. The head center pitch of the head 3, the number of main spindle drive motors, and power transmission positions are set in accordance with the number of the heads 3 in the following manner. That is, in order to suppress the increase in the length of the multi-needle embroidery machine as the increase in the number of the sewing machine heads, each head center pitch of the sewing machine heads to be arranged as close as possible is set to 135 mm in accordance with the transverse dimension when the sewing machine head 3 includes 5 needles arranged. When the sewing machine head 3 includes 9 needles arranged, the pitch is set to 240 mm in accordance with the transverse dimension. The following head center pitch is set so as not to be excessive considering the case where the sewing machine heads are arranged as close as possible. The number of the needles arranged on the sewing machine head 3 may be -3 to -4,-or 10 to 15 (1) In the multi-head embroidery machine 1 including 31 to 50 units of aforementioned sewing machine heads 3, the head center pitch of the heads 3 is set to 135 to 300 mm (preferably, 135 to 240 mm) , and power transmission positions of two motors 12 are set at both end portions of the main spindle 4 (first embodiment). The number of the sewing machine heads 3 may be set to 21 to 30, or 51 to 70. The head center pitch of the heads 3 may be set to 300 to 400 mm. (2) In a multi-head embroidery machine 21 including 11 to 30 units of aforementioned sewing machine heads 3, the head center pitch of the head 3 is set to 160 to 300 mm (preferably, 160 to 240 mm) , and the power transmission position of a motor 22 is set at the center portion of the main spindle 4 (second embodiment) . The head center pitch of the head 3 may be set to 300 to 400 mm. (3) In a multi-head embroidery machine 31 including 51 to 70 units of aforementioned sewing machine heads 3, the head center pitch of the heads 3 is set to 135 to 300 mm (preferably, 135 to 240 mm) , and the power transmission positions of three motors 32 are set to both end portions and the center portion of the main spindle 4 (third embodiment) . The head center pitch of the heads 3 may be set to 300 to 400 mm. First Embodiment As shown in FIG. 2, in the multi-head embroidery machine 1 according to a first embodiment, 31 to 50 units of sewing machine heads 3 (each including 5 to 9 needles) are arranged in a transverse line on the front surface of the machine frame 2 at a regular head center pitch (PI) of 135 to 300 mm. The main spindle 4 is provided to extend through all the heads 3, and driven by the two motors 12 . The motor 12 is provided at the back surface of the machine frame 2, and has its output shaft 13 connected to both end portions of the main spindle 4 via a pulley 14, a belt 15 and a pulley 16. The diameter of—the-main-in-spindle-4--is set to φ 2 20mm -and-the output-of- the— motor 12 is set to 1.5 kW (1.5 kJ/s) , for example. Standard components designed for existing embroidery machines may be employed as the respective power system components including the pulleys 14, 16 and the belt 15. In the multi-head embroidery machine 1 according to the embodiment, the head center pitch (PI) of the sewing machine heads 3 is set to 135 to 300 mm. This allows the extension length of the main spindle 4 owing to the increase in the number of the heads to be suppressed as short as possible. In addition, because the two motors 12 transmit the power to both end port ions of the main spindle 4, the twist of the main spindle 4 may be reduced substantially by half compared with a one-side power drive type. Accordingly, many standard components for the existing embroidery machine may be used for the drive system of the main spindle 4, and the multi-head embroidery machine 1 including maximum of 50 heads may be manufactured at low costs. In the case where the head center pitch (PI) of the sewing machine heads 3 is set to an especially small value (for example, 135 to 240 mm) , if an output shaft 23 of the motor 22 is intended to be connected to the center portion of the main spindle 4 as in the second embodiment, the head center pitch needs to be, expanded only in the center portion. However, the first embodiment eliminates the need of expanding the pitch in the center portion. Second Embodiment As shown in FIG. 3, in the multi-head embroidery machine 21 according to a second embodiment, 11 to 30 units of sewing machine heads 3 (each including 5 to 9 needles) are arranged in a transverse line on the front surface of the machine frame 2 at a regular head center pitch (P2) of 160 to 300 mm. The main spindle 4 is provided to extend through all the heads 3, and driven by the single motor 22 . The motor 22 is disposed -on-the back-surface of the machine frame-2-at the-center~thereof. The output shaft 23 is connected to the center portion of the main spindle 4 via a pulley 24, a belt 25 and a pulley 26. Likewise the first embodiment, standard components designed for existing embroidery machines may be employed as the respective power system components including the main spindle 4, the motor 22, the pulleys 24, 26 and the belt 25. In the multi-head embroidery machine 21 according to the embodiment, the head center pitch (P2) of the sewing machine head 3 is set to 160 to 300 mm, and the single motor 22 is connected to the center port ion of the main spindle 4. Likewise the first embodiment, many standard components may be used to suppress the twist of the main spindle 4 to allow manufacturing of the multi-head embroidery machine 21 including the maximum of 30 heads at low costs. Especially, because the sewing machine heads 3 are arranged at the relatively large head center pitch (P2), a large number of needle bars 5 may be arranged on each of the heads 3 so as to structure the embroidery machine 21 suitable for processing of multi-color embroidery patterns. Third Embodiment As shown in FIG. 4, in the multi-head embroidery machine 31 according to a third embodiment, 51 to 70 units of sewing machine heads 3 (each including 5 to 9 needles) are arranged in a transverse line on the front surface of the machine frame 2 at a regular head center pitch (P3) of 135 to 300 mm. The main spindle 4 is provided to extend through all the heads 3, and driven by three motors 32 . The motors 32 are provided on the back surface of the machine frame 2 at left and right end portions and the center portion thereof, and have respective output shafts 33 connected to both end portions and the center portion of the main spindle 4 via pulleys 34, belts 35 and pulleys 36. Likewise the first embodiment, standard components designed for existing embroidery machines -may be employed as the respective power system components-including the main spindle 4, the motors 32, the pulleys 34, 36 and the belts 35. In the multi-head embroidery machine 31 according to the embodiment, especially the three motors 32 are connected to both end portions and the center portion of the main spindle 4. Therefore, in the multi-head embroidery machine 31 including a maximum of 70 heads, the twist of the main spindle 4 may be suppressed by the low cost structure using the standard components. This makes it possible to form various kinds of embroidery pat terns on a large working fabric such as a clothing fabric efficiently with high precision. Note that the present invention is not limited to the embodiments as described above and may be formed by modifying the structures of the respective components without departing from the scope of the present invention as follows. (1) The hook drive shaft (lower shaft) which penetrates the bed 7 may be synchronized with the main spindle 4 by the motors 12, 22 and 32. (2) According to the modified example of the first embodiment shown in FIG. 5, a sequin supply unit 40 is provided at an end portion of each of the sewing machine heads 3. The sequin supply unit 40 supplies the sequin onto the working fabric so as to be sewn with the needle at the end portion. A left motor 12 is disposed at the left end inside the rectangular cylindrical machine frame 2 including the sewing machine heads 3 arranged thereon, and a right motor 12 is disposed at the right end of the back side of the machine frame 2 . Each output of the respective motors 12 is set to 750 W (750 J/s), for example. The two motors 12 are driven by an inverter type driver (r. t shown) with a capacity of 1.5 kW (1.5 J/s) . The motor with the output of 750 W is smaller in size than the one with the output of 1.5 kW or higher that is used in multi-needle embroidery machines of generally employed type. -This may provide the high degree of freeedom in arrangement and be structured at the lower costs. The inverter type driver with the capacity of 1.5 kW or higher which has been used in the multi-needle embroidery machine of generally employed type may be used. The present inventor hasdiscovered that the total output of two motors disposed at both end portions of the main spindle is sufficient to smoothly drive the main spindle to be rotated in spite of being slightly lower than the output of a single motor used to drive one end of the main spindle in the general case. (3) In the first to the third embodiments, the number of the needles arranged on the sewing machine head 3 may be set to 3 to 4, or 10 to 15. (4) In the first embodiment, the number of the sewing machine heads 3 may be set to 2.1 to 30, or 51 to 70, and the head center pitch of the heads 3 may be set to 300 to 400 mm. (5) In the second embodiment, the head center pitch of the heads 3 may be set to 300 to 400 mm. (6) In the third embodiment, the head center pitch of the heads 3 may be set to 300 to 400 mm. WE CLAIM 1. A multi-head embroidery machine characterized in that 21 to 70 units of sewing machine heads each having arranged 3 to 15 needles are arranged in a line on a machine frame at a head centre pitch of 135 to 400 mm; and a main spindle common to all the sewing machine heads is driven by two motors connected to both end portions of the main spindle. 2. The multi-head embroidery machine as claimed in claim 1, wherein 51 to 70 units of the sewing machine heads each having arranged 3 to 15 needles are arranged in a line on a machine frame at a head centre pitch of 135 to 400 mm; and The main spindle common to all the sewing machine heads is driven by three motors connected to both end portions and a centre portion of the main spindle.

Documents:

1144-del-2007-abstract.pdf

1144-DEL-2007-Claims-(09-08-2011).pdf

1144-del-2007-claims.pdf

1144-DEL-2007-Correspondence Others-(09-08-2011).pdf

1144-del-2007-Correspondence Others-(24-05-2011).pdf

1144-DEL-2007-Correspondence Others-(25-07-2011).pdf

1144-del-2007-correspondence-others-1.pdf

1144-del-2007-correspondence-others.pdf

1144-del-2007-description (complete).pdf

1144-del-2007-drawings.pdf

1144-DEL-2007-Form-1-(09-08-2011).pdf

1144-del-2007-form-1.pdf

1144-del-2007-form-18.pdf

1144-DEL-2007-Form-2-(09-08-2011).pdf

1144-del-2007-form-2.pdf

1144-DEL-2007-Form-3-(09-08-2011).pdf

1144-DEL-2007-Form-3-(25-07-2011).pdf

1144-del-2007-form-3.pdf

1144-del-2007-form-5.pdf