DOUBLE NEEDLE SEWING METHOD ENABLING CHANGEABLE NEEDLE DISTANCE

Abstract

 A double needle sewing method enabling changeable needle distance includes a data acquiring step to acquire a sequence of stitching information according to two sewing lines; a stitches moving step to horizontally move a fabric workpiece by an XY-axis feeding mechanism according to movement coordinate data in the stitching information; a stitches rotating step to axially rotate a needle bar of the sewing machine by a rotatable needle bar mechanism according to rotational angle data in the stitching information, and to horizontally rotate a needle plate and a shuttle hook synchronous with the needle bar's axial rotation by a needle plate rotating mechanism according to the rotational angle data; and a needle distance changing step to displace the two needles by a needle distance adjustment mechanism according to needle distance data in the stitching information, so that different needle distances can be produced during stitching of the two sewing lines.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a double needle sewing method used on a computerized double needle sewing machine, and more particularly, to a sewing method that enables changing of needle distance between a plurality of paired stitching points on two parallel sewing lines formed by a double needle sewing machine.

BACKGROUND OF THE INVENTION

[0002] Due to the development in automated and high-speed sewing machine field, many currently available industrial sewing machines are not only labor-saving and high-productivity, 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 driving mechanism to automatically move a fabric workpiece and enable 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.

[0003] Among others, two parallel sewing lines formed using a double needle sewing machine create better aesthetic effect on a fabric workpiece, so that double needle sewing is frequently applied to form patterns on various clothing by people daily life. Figs. 1, 2A and 2B illustrate a double needle rotatable head pattern sewing machine 9 that is a computer-controlled sewing machine having two needles 903 for sewing synchronously. On a top of the double needle rotatable head pattern sewing machine 9, there is a head rotating mechanism 90; and a base rotating mechanism 91 and an XY-axis feeding mechanism 92 are located below the head rotating mechanism 90. The head rotating mechanism 90 includes a rotating adaptor 901 that brings a needle bar 902 to rotate, and the base rotating mechanism 91 brings a needle plate 911 and a shuttle hook mechanism (not shown) to rotate synchronous with the needle bar 902, so that two needle holes 912 on the needle plate 911 can always be aligned with the two needles 903 in one-to-one correspondence. The XY-axis feeding mechanism 92 includes a jig, via the jig the fabric workpiece is brought to move horizontally. In this way, the double needle rotatable head pattern sewing machine 9 can be used in replace of the conventional manual double needle sewing machine to form two juxtaposed parallel sewing lines 93 at higher sewing efficiency.

[0004] However, there are various types of sewing fabric materials, some of them are relatively thick while others are relatively thin; and some of them are relatively hard while others are relatively soft. Different sewing fabric materials would require different needle distances and different stitch lengths. Generally, the needle distance for the two needles of the double needle has to be larger for thick and hard fabric materials and has to be smaller for thin or soft fabric materials. Therefore, in the case of double needle sewing, a needle holder 904 and the needle plate 911 needed in the whole sewing process must be changed according to predetermined needle distances.

[0005] Further, in general double needle sewing, the needle distance 903a between the two needles 903 has to be maintained the same. Therefore, it is not possible to form patterns other than two parallel sewing lines using the conventional double needle sewing machine. In addition, when the double needle rotatable head pattern sewing machine 9 is used to sew along a curved sewing path 94, the stitches formed by the two needles 903 at curved sections would be different from a preset stitch length 95. Since the two needles 903 move synchronously in an upward and downward motion, and a line segment connecting the two needles 903 is perpendicular to the curved sewing path 94, the actual stitch lengths 931, 932 of the two parallel sewing lines 93 along the curved sewing path 94 would be obviously different from one another, which often results in reduced aesthetic look of the fabric workpiece.

SUMMARY OF THE INVENTION

[0006] A primary object of the present invention is to provide a double needle sewing method; with the method, a distance between two needles of a double needle sewing machine is changeable according to a sequence of setting data during the course of sewing two parallel lines using the double needle sewing machine, so that the two parallel sewing lines can not only maintain the same width between them, but also keep the same length for all the stitches along the sewing lines. In this way, more patterns of great aesthetically pleasing can be formed with the double needle sewing machine, and accordingly, the utilization of the double needle sewing machine is largely improved.

[0007] Another object of the present invention is to provide a double needle sewing method; with the method, a double needle sewing machine can be used on the same fabric material to sew a plurality of patterns of parallel lines spaced by different widths, or to form patterns of sewing lines that have changing widths on the same double line sewing path, so that the types of pattern that can be sewed with the double needle sewing machine are increased.

[0008] To achieve the above and other objects, the double needle sewing method provided according to the present invention is mainly implemented on a double needle sewing machine having an XY-axis feeding mechanism, a rotatable needle bar mechanism, a needle plate rotating mechanism and a needle distance adjustment mechanism; and a distance between two needles of the double needle sewing machine is adjustable and changeable within a set distance range during the course of stitching two sewing lines. And, the set distance range can be one falling between a maximum adjustment value and a minimum adjustment value set in the needle distance adjustment mechanism, or one defined by a maximum reference value and a minimum reference value preset by a user.

[0009] The double needle sewing method includes a data acquiring step, a stitches moving step, a stitches rotating step, and a needle distance changing step. In the data acquiring step, a plurality of pieces of stitching information presented in sequence are acquired according to the two sewing lines; and each piece of the stitching information includes a movement coordinate data, a rotational angle data and a needle distance data. In the stitches moving step, a fabric workpiece is horizontally moved by the XY-axis feeding mechanism according to those movement coordinate data sequentially. In the stitches rotating step, a needle bar of the sewing machine is brought by the rotatable needle bar mechanism to axially rotate according to those rotational angle data sequentially; and a needle plate and a shuttle hook are brought by the needle plate rotating mechanism to rotate horizontally synchronous with the axial rotation of the needle bar, also according to those rotational angle data sequentially. And. In the needle distance changing step, the two needles of the double needle sewing machine are caused by the needle distance adjustment mechanism to displace according to those needle distance data sequentially for changing a width between the needles, so that a plurality of needle distances of different lengths are produced for the two needles while the two sewing lines are continuously stitched.

[0010] According to a preferred embodiment of the present invention, the data acquiring step includes a sewing line setting procedure, a stitch point setting procedure, and a data generating procedure. In the sewing line setting procedure, two sewing lines to be formed on the fabric workpiece are acquired and a stitch length is set for the two sewing lines. In the stitch point setting procedure, a starting stitch position is set up for each of the two sewing lines, based on the a plurality of first line's stitching points and a plurality of second line's stitching points are sequentially formed for each of the two sewing lines according to the stitch length. In the data generating procedure, a line segment is drawn to connect each pair of the first line's stitching point and the second line's stitching point that have the same sequential position in the two sewing lines, so as to obtain a plurality of needle distance data; and all the first line's stitching points, all the second line's stitching points and all the needle distance data are computed to generate the movement coordinate data and the rotational angle data in each piece of the stitching information.

[0011] The data acquiring step further includes a calibrating procedure, all the needle distance data are compared with the set distance range in the calibrating procedure; a perform sewing instruction is generated by the double needle sewing machine in the case all the needle distance data fall in the set distance range; and the stitch starting positions for the two sewing lines are reselected in the case any one of those needle distance data is larger than or smaller than the set distance range.

[0012] The double needle sewing machine generates a reminder of resetting the stitch length, in the event the stitch starting positions are reselected many times in the calibrating procedure without successfully generating the perform sewing instruction.

[0013] Each of those movement coordinate data is selected from the coordinate of a central point in a corresponding needle distance data; and all the central point coordinates are computed to generate a working path, so that the XY-axis feeding mechanism brings the fabric workpiece to move horizontally along the working path.

[0014] According to an operable embodiment, the needle distance adjustment mechanism fixes one of the two needles to a reference position that is aligned with an axis of the needle bar while the other one is displaceable relative to the fixed needle to change the length of the needle distance.

[0015] According to another operable embodiment, the needle distance adjustment mechanism sets the two needles to be located at two sides of and equally spaced from the axis of the needle bar, and causes the two needles to displace synchronously to change the length of the needle distance.

[0016] The needle plate rotating mechanism in the above embodiment further includes a set of two shifting devices. According to those needle distance data, the shifting devices bring two needle holes on the needle plate to displace synchronous with and corresponding to the two needles, so that the two needle holes are always in alignment with the two needles during the sewing process.

[0017] The present invention is characterized in that the distance between the two needles and the rotational angles of the two needles are changed in real time for all the stitches formed on the fabric workpiece to meet the preset stitch length when the two needles are actually sewing along two sewing paths, so that aesthetic sewing lines having consistent stitch lengths are formed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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. 1 is a perspective view of a conventional double needle rotatable head pattern sewing machine with an enlarged view of two needles and a needle plate thereof;

Figs. 2A and 2B show the manner in which the conventional double needle sewing machine of Fig. 1 forms a sewing path;

Fig. 3 is a structural view of a double needle sewing machine according to a first embodiment of the present invention;

Fig. 4 is a block flow chart showing the steps included in a double needle sewing method according to the present invention;

Fig. 5 is a block flow chart showing the procedures included in a data acquiring step of the method show in Fig. 4;

Fig. 6 shows an operable embodiment of the present invention, in which only one needle on the double needle of the sewing machine is displaceable and rotatable;

Fig. 7 shows two sewing lines formed on a fabric workpiece according to a first embodiment of the method of the present invention;

Fig. 8 shows another operable embodiment of the double needle sewing machine of the present invention, in which the two needles on the double needle are displaceable and rotatable synchronously;

Fig. 9 shows two sewing lines formed on a fabric workpiece according to a second embodiment of the method of the present invention; and

Fig. 10 is a structural view of the double needle sewing machine in Fig. 8, showing two shifting devices thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 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.

[0020] Please refer to Fig. 3 that shows a double needle sewing machine 1, on which a double needle sewing method enabling changeable needle distance according to the present invention is implemented. As shown, the double needle sewing machine 1 includes a double needle having two needles 10, a rotatable needle bar mechanism 11 and a needle distance adjustment mechanism 12 located on a sewing head of the sewing machine 1, as well as a needle plate rotating mechanism 13 and an XY-axis feeding mechanism (not shown) provided on a base of the sewing machine 1, so that a needle distance between the two needles 10 of the sewing machine 1 is adjustable and changeable within a set distance range during the course of forming two sewing lines 2 such as that shown in Fig. 7.

[0021] In an operable embodiment, the set distance range can be one falling between a maximum adjustment value and a minimum adjustment value of a designed adjustable distance range for the two needles 10 set in the needle distance adjustment mechanism 12, or one defined by a maximum reference value and a minimum reference value directly set by a user. The maximum reference value shall be smaller than or equal to the maximum adjustment value, and the minimum reference value shall be larger than or equal to the minimum adjustment value.

[0022] Please refer to Fig. 4 that shows the steps included in the double needle sewing method according to the present invention. As shown, the method includes a data acquiring step 3, a stitches moving step 4, a stitches rotating step 5, and a needle distance changing step 6.

[0023] In the data acquiring step 3, moving tracks of two sewing lines 2 to be formed on a fabric workpiece 7 are computed, so that a plurality of pieces of stitching information, such as first stitching information, second stitching information, third stitching information, etc., are acquired according to their sequence in the moving tracks. Each piece of stitching information includes a movement coordinate data, a rotational angle data, and a needle distance data 25.

[0024] In the stitches moving step 4, the fabric workpiece 7 is moved horizontally by the XY-axis feeding mechanism according to those movement coordinate data sequentially. The fabric workpiece 7 can be horizontally moved in a single linear direction along the X-axis, in a single linear direction along the Y-axis, or in an oblique direction between the X-axis and the Y-axis.

[0025] In the stitches rotating step 5, a needle bar 111 of the sewing machine 1 is brought by the rotatable needle bar mechanism 11 to rotate around its axis according to those rotational angle data sequentially. Meanwhile, the needle plate rotating mechanism 13 brings a needle plate 131 and a shuttle hook 132 of the sewing machine 1 to rotate multiple times synchronous with the needle bar's axial rotation according to those rotational angle data sequentially.

[0026] In the needle distance changing step 6, the needle distance adjustment mechanism 12 brings the two needles 10 to displace according to those needle distance data 25 sequentially, so as to change a length of the needle distance. By doing this, it is able to create a plurality of needle distances of different lengths for the two needles 10 while the two sewing lines 2 are continuously formed.

[0027] Please refer to Figs. 5 to 7. The data acquiring step 3 includes a sewing line setting procedure 31, a stitching point setting procedure 32, a data generating procedure 33, and a calibrating procedure 34.

[0028] First, in the sewing line setting procedure 31, let the double needle sewing machine 1 acquire two parallel sewing lines 2 that are set to be formed on the fabric workpiece 7 and let a user preset a stitch length 21 for the double needle sewing machine 1, so that the sewing machine 1 acquires a sewing line setting data consisting of the two sewing lines 2 and the stitch length 21. However, it is understood the aforesaid parallel sewing lines 2 are only illustrative description for keeping the same stitch length 21. In other words, it is possible to have different distances between the two sewing lines 2 at some sections thereof, so that the two sewing lines 2 are presented in a non-parallel state (not shown). In this way, more different patterns can be created using the double needle sewing machine.

[0029] Then, in the stitching point setting procedure 32, a computer device on the double needle sewing machine 1 set up a starting stitch position 22 for each of the two sewing lines 2, a plurality of equally spaced first line's stitching points 23 are formed for one of the two sewing lines 2 according to the stitch length 21, and a plurality of equally spaced second line's stitching points 24 are formed for the other sewing line 2 also according to the stitch length 21.

[0030] In the data generating procedure 33, the computer device uses a line segment to connect each pair of the first line's stitching point 23 and the second line's stitching point 24 that have the same sequential position in the two sewing lines 2, so as to obtain a plurality of needle distance data 25 from these line segments. As can be seen in Fig. 7, a first needle distance data 25 is generated by a line segment connecting and extending between a first line's stitching point 23a and a second line's stitching point 24a that are respectively located at the first position on the two sewing lines 2; and a second needle distance data 25 is generated by a line segment connecting and extending between a first line's stitching point 23b and a second line's stitching point 24b that are respectively located at the second position on the two sewing lines 2. In the same manner, a third, a fourth to an n^th needle distance data 25 can be generated. Thereafter, all the first stitching points 23, all the second stitching points 24 and all the needle distance data 25 are used to generate the movement coordinate data and the rotational angle data.

[0031] In the calibrating procedure 34, the computer device compares all the needle distance data 25 with the set distance range. In the case all the needle distance data 25 fall in the set distance range, the computer device would generate a perform sewing instruction to the double needle sewing machine. On the other hand, in the case any one of the needle distance data 25 is larger or smaller than the set distance range, the computer device would not transmit the perform sewing instruction but reselects a new stitch starting position 22 for each of the two sewing lines 2, and uses the new stitch starting positions 22 instead of the initial ones to conduct the calibrating procedure 34 again. In the event the stitch starting positions 22 are reselected many times in the calibrating procedure 34 without successfully generating the perform sewing instruction, the double needle sewing machine 1 will generate a reminder for the user to reset the stitch length 21.

[0032] In the operable embodiment shown in Fig. 6, the needle distance adjustment mechanism 12 fixes one of the two needles 10 to a reference position that is aligned with an axis of the needle bar 111 while the other one is displaceable relative to the fixed needle 10 to change the length of the needle distance, i.e. the first needle distance data, the second needle distance data, etc. Meanwhile, the needle plate 131 has two needle holes 133, one of the two needle holes 133 is located at a fixed reference position aligned with the axis of the needle bar 111 and the other one is also displaceable relative to the fixed one to a position corresponding to the displaceable needle 10.

[0033] Please refer to Figs. 8 and 10, in which another operable embodiment of the present invention is shown. In this embodiment, the needle distance adjustment mechanism 12 sets the two needles 10 to be located at two sides of and equally spaced from the axis of the needle bar 111, and causes the two needles 10 to displace synchronously to change the length of the needle distance. In this embodiment, each of those movement coordinate data can be selected from the coordinate of a central point of a corresponding needle distance data 25, and these central point coordinates are computed to generate a working path 26 as shown in Fig. 9, so that the XY-axis feeding mechanism brings the fabric workpiece 7 to move horizontally along the working path 26. Meanwhile, the needle bar 111 is axially rotated according to the rotational angle data sequentially, and the needle plate 131 and two shuttle hook 132 are rotated according to those rotational angle data sequentially and synchronous with the axial rotation of the needle bar 111. In this manner, the two needles 10 can form the first line's stitching points 23 and the second line's stitching points 24 on the two sewing lines 2.

[0034] As shown in Fig. 10, the needle plate rotating mechanism 13 includes a set of two shifting devices 134. According to those needle distance data 25, the shifting devices 134 bring the two needle holes 133 on the needle plate 131 and the two shuttle hooks 132 to displace synchronous with and relative to the two needles 10, so that the two needle holes 133 are always in alignment with the two needles 10 during the sewing process.

[0035] Compared to Fig. 3, the embodiment shown in Fig. 10 can form linear sewing lines with double bottom threads and double top threads, which show the same effect as that of two sewing lines separately formed by a single needle sewing machine. Therefore, as shown in Fig. 10, the two shuttle hooks 132 with vertical axis must be horizontally shifted synchronous with the two needle holes 133, respectively. On the other hand, in the embodiment shown in Fig. 3, one shuttle hook 132 with horizontal axis is used and there is only one needle hole 133 in the form of an elongated slot, so that one bottom thread on the sewing machine 1 can be alternately caught with the top thread from the two needles 10 without horizontally shifting the needle hole 133, so long as the needles 10 are moving within a preset needle distance range. In this case, only the needle plate 131 and the shuttle hook 132 are brought by the needle plate rotating mechanism 13 to rotate horizontally synchronous with the needle bar 111. In this embodiment, sewing lines 2 with a zigzag stitch line on the bottom of the fabric workpiece can be formed and have the same effect as that formed with a double needle single bottom thread sewing machine.

[0036] The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.

Claims

1. A double needle sewing method enabling changeable needle distance, for implementation on a double needle sewing machine having an XY-axis feeding mechanism, a rotatable needle bar mechanism, a needle plate rotating mechanism and a needle distance adjustment mechanism, and a distance between two needles of the sewing machine being adjustable and changeable within a set range during the course of stitching two sewing lines, comprising:

a data acquiring step, in which a plurality of pieces of stitching information presented in sequence are acquired according to two sewing lines that are to be formed on a fabric workpiece; and each piece of the stitching information including a movement coordinate data, a rotational angle data and a needle distance data;

a stitches moving step, in which the fabric workpiece is horizontally moved by the XY-axis feeding mechanism according to those movement coordinate data sequentially;

a stitches rotating step, in which a needle bar of the sewing machine is brought by the rotatable needle bar mechanism to axially rotate according to those rotational angle data sequentially, and a needle plate and a shuttle hook are brought by the needle plate rotating mechanism to rotate horizontally and synchronous with the axial rotation of the needle bar also according to those rotational angle data sequentially; and

a needle distance changing step, in which the two needles of the sewing machine are caused by the needle distance adjustment mechanism to displace according to those needle distance data sequentially, so as to change a length of the needle distance; whereby a plurality of needle distances of different lengths are produced while the two sewing lines are continuously stitched by the two needles.

2. The double needle sewing method enabling changeable needle distance according to claim 1, wherein the data acquiring step includes:

a sewing line setting procedure, in which the two sewing lines to be formed on the fabric workpiece are acquired and a stitch length is set for the two sewing lines;

a stitch point setting procedure, in which a starting stitch position is set up for each of the two sewing lines, based on which a plurality of first line's stitching points and a plurality of second line's stitching points are sequentially formed for each of the two sewing lines according to the stitch length; and

a data generating procedure, in which a line segment is used to connect each pair of the first line's stitching point and the second line's stitching point that have the same sequential position in the two sewing lines, so as to obtain a plurality of needle distance data from these line segments; and all the first line's stitching points, all the second line's stitching points and all the needle distance data are computed to generate the movement coordinate data and the rotational angle data in each pieces of the stitching information.

3. The double needle sewing method enabling changeable needle distance according to claim 2, wherein the data acquiring step further includes:
a calibrating procedure, in which all the needle distance data are compared with the set distance range; a perform sewing instruction is generated by the double needle sewing machine in the case all the needle distance data fall in the set distance range; and the stitch starting positions for the two sewing lines are reselected in the case any one of those needle distance data is larger than or smaller than the set distance range.

4. The double needle sewing method enabling changeable needle distance according to claim 3, wherein the double needle sewing machine generates a reminder of resetting the stitch length, in the event the stitch starting positions are reselected many times in the calibrating procedure without successfully generating the perform sewing instruction.

5. The double needle sewing method enabling changeable needle distance according to claim 3, wherein each of those movement coordinate data is selected from the coordinate of a central point of a corresponding needle distance data; and wherein the central point coordinates are computed to generate a working path, so that the XY-axis feeding mechanism brings the fabric workpiece to move horizontally along the working path.

6. The double needle sewing method enabling changeable needle distance according to claim 1, wherein the set distance range can be one falling between a maximum adjustment value and a minimum adjustment value set in the needle distance adjustment mechanism, or one defined by a maximum reference value and a minimum reference value preset by a user.

7. The double needle sewing method enabling changeable needle distance according to claim 1, wherein the needle distance adjustment mechanism fixes one of the two needles to a reference position that is aligned with an axis of the needle bar while the other one is displaceable relative to the fixed needle to change the length of the needle distance.

8. The double needle sewing method enabling changeable needle distance according to claim 1, wherein the needle distance adjustment mechanism sets the two needles to be located at two sides of and equally spaced from an axis of the needle bar, and causes the two needles to displace synchronously to change the length of the needle distance.

9. The double needle sewing method enabling changeable needle distance according to claim 1, wherein the needle plate rotating mechanism further includes a set of two shifting devices; according to those needle distance data, the shifting devices bringing two needle holes on the needle plate to displace synchronous with and relative to the two needles, so that the two needle holes are always in alignment with the two needles during the sewing process.

Drawing