JP2008023261A - Sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form stitches with excellent appearance by reliably preventing hitch stitches even in the case of any stitch forming directions regardless of a sewing speed. <P>SOLUTION: Pattern sewing control is started (S11) and stitch data is read (S15). Then, the stitch forming direction from the needle fall position of the (I-1)-th stitch toward the needle fall position of the first stitch is calculated (S17). When the calculated stitch forming direction is within a stitch forming direction range and also a route switch mechanism is switched (S18:Yes, S20:Yes), the rotation speed of a sewing machine motor is forcibly decelerated so as to slow down the sewing speed (S22). Thus, a time till a sewing needle pierces a fabric to be processed is prolonged, so that a bobbin thread feeding route is alternatively and reliably switched to a right route and a left route till the sewing needle pierces the fabric to be processed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sewing machine that avoids the occurrence of hitch stitches by appropriately switching the entanglement direction of the lower thread with respect to the sewing needle regardless of the direction in which the stitches are formed on the work cloth. .

  Conventionally, according to the cloth feed direction of the work cloth used for sewing, that is, the stitch formation direction, the entanglement direction (right-handed or left-handed) where the upper thread that has passed through the stitch hole of the sewing needle when the sewing needle pierces the work cloth is entangled with the sewing needle. The direction is different, and the perfect thread or hitch stitch is determined depending on whether the lower thread falls on the left or right side of the needle. When hitch stitches are used, it is well known that the stitches are not good looking due to weak thread tightening.

For example, the sewing machine feed control device described in Patent Document 1 includes a feed direction calculation means and a feed direction determination means, and the feed direction in which the cloth is fed from each needle drop position to the next needle drop position is set in advance. In the case of belonging to the hitch stitch direction, the feed end time is delayed more than in the case of belonging to the perfect stitch, the upper thread is tightened strongly, and the appearance of the seam is made beautiful.
JP 2000-153085 A (pages 5-6, FIG. 7)

  In the sewing machine feed control device described in Japanese Patent Laid-Open No. 2004-228561, the stitches formed in the hitch stitch are made to look beautiful by strengthening the thread tightening at the time of the hitch stitch. That is, the hitch stitch is not generated so as not to occur, that is, the hitch stitch is not positively eliminated. Therefore, paying attention to the positional relationship between the sewing needle and the lower thread when the stitch is stabbed into the work cloth under the condition that the stitch becomes a hitch stitch, the lower thread is switched to the left or right side with respect to the vertical movement locus of the sewing needle. It is possible.

  However, when the sewing machine motor rotates at high speed, that is, when the sewing speed is high, the sewing cycle is short, so the switching between the right side and the left side of the lower thread exit is not in time, and hitch stitching can be prevented reliably. There is a problem that you can not.

  The object of the present invention is to appropriately switch the lower thread supply path for supplying the lower thread from the bobbin case to the needle hole of the needle plate between the left route and the right route according to the stitch formation direction, regardless of the sewing speed. It is to be able to reliably prevent the occurrence of hitch stitches and to form beautiful seams with good appearance.

  The sewing machine according to a first aspect of the present invention has a sewing needle that is driven up and down by rotation of a main shaft driven by a sewing motor, a rotary hook that is rotated in conjunction with the rotation of the main shaft, and a work cloth in two different directions based on sewing data. Cloth feeding means for feeding the cloth independently, and further, the lower thread supply path from the rotary hook to the needle hole of the needle plate is biased to the left side and the right side biased to the left side with respect to the vertical movement locus of the sewing needle. The switching means that can be switched selectively to the right-hand route, and the stitch formation direction range for the stitch needle that becomes the hitch stitch is preset and stored for each of the left-hand route and the right-hand route that are switched by the switching means. Direction setting means, stitch direction calculation means for calculating a stitch formation direction from each needle drop position to the next needle drop position based on stitch data for each needle drop position in the sewing data, Eye direction The stitch formation direction calculated by the means is determined to belong to the stitch formation direction range of the hitch stitch set by the stitch direction setting means, and the determination result of the determination means is received. When the forming direction belongs to the stitch direction range set by the stitch direction setting means, the switching means is switched and controlled so that the stitch is not the hitch stitch but the perfect stitch after the rotation speed of the sewing machine motor is reduced. And a switching control means.

  For each of the left route where the lower thread supply path from the rotary hook to the needle hole of the needle plate is biased to the left side and the right route which is biased to the right side, the stitch formation direction range for the stitch needle that becomes the hitch stitch is the stitch direction setting means. Since it is set and stored in advance, the stitch formation direction from each needle drop position to the next needle drop position is calculated based on the stitch data for each needle drop position in the sewing data. It is determined whether the stitch formation direction belongs to the stitch formation direction range of the hitch stitch.

  Therefore, according to this determination result, when the stitch formation direction belongs to the stitch direction range based on the currently switched lower thread supply path, the rotational speed of the sewing machine motor is reduced and the time until the sewing needle pierces the work cloth is reduced. In the extended state, the switching means is controlled to switch so that the stitch is not a hitch stitch but a perfect stitch. Therefore, the lower thread supply path can be selectively switched between the left route and the right route so that the hitch stitch does not occur before the sewing needle pierces the work cloth.

  A sewing machine according to a second aspect is the sewing machine according to the first aspect, wherein the switching means is an engagement member that engages with a lower thread of a lower thread supply path, and an actuator that selectively switches the engagement member between a left position and a right position. It has.

  The sewing machine according to a third aspect of the present invention is the sewing machine according to the second aspect, wherein the switching control means has switching detection means for detecting completion of switching of the engaging member by the actuator, and outputs a switching instruction for the lower thread supply path and then detects the switching. When the completion of switching of the engaging member is not detected by the means, the sewing machine motor is stopped when the sewing needle is equal to or larger than the switching limit angle that is a predetermined angle of the main shaft.

  A sewing machine according to a fourth aspect is the sewing machine according to the third aspect, wherein the switching control means changes the switching limit angle to be smaller as the rotational speed of the sewing machine motor becomes higher.

  According to a fifth aspect of the present invention, in the third or fourth aspect, the switching control means repeatedly outputs a switching command until the switching limit angle is reached when the switching detection means does not detect completion of switching of the engaging member. .

  According to the first aspect of the present invention, the work cloth is different on the basis of the sewing data, the sewing needle driven up and down by the rotation of the main shaft driven by the sewing machine motor, the rotary hook rotated in conjunction with the rotation of the main shaft, and the sewing data. In the sewing machine provided with the cloth feeding means for independently feeding the cloth in the direction, since the switching means, the stitch direction setting means, the stitch direction calculating means, the discrimination means, and the switching control means are provided, the switching means , Even if the sewing speed is high, the rotational speed of the sewing machine motor is forcibly decelerated and the time until the sewing needle pierces the work cloth is extended. The lower thread supply route can be switched selectively between the left route and the right route. Therefore, regardless of the sewing speed, it is possible to reliably prevent hitch stitches from being produced and to sew with beautiful stitches only with perfect stitches.

  According to a second aspect of the present invention, the switching means includes an engagement member with which the lower thread of the lower thread supply path is engaged, and an actuator that selectively switches the engagement member between the left position and the right position. Therefore, the switching means can be configured simply, and the lower thread supply path can be quickly switched between the left root and the right root through the position switching of the engaging member only by switching the driving of the actuator. Other effects similar to those of the first aspect are obtained.

  According to a third aspect of the present invention, the switching control means has switching detection means for detecting completion of switching of the engaging member by the actuator, and outputs a lower thread supply path switching command, and then the switching detection means If the completion of the switching of the joint member is not detected, the sewing machine motor stops driving if the sewing needle exceeds the switching limit angle, which is the predetermined angle of the main spindle. The hitch stitch can be surely recognized. Other effects similar to those of the second aspect are achieved.

  According to the invention of claim 4, the switching control means changes so as to reduce the switching limit angle as the rotational speed of the sewing machine motor increases, so that the sewing speed can be high or low. Thus, it is possible to reliably prevent hitch stitches from occurring due to a delay in switching the lower thread supply path. Other effects similar to those of the third aspect are achieved.

  According to the invention of claim 5, the switching control means repeatedly outputs a switching command until the switching limit angle is reached when the switching detection means does not detect completion of switching of the engaging member. Switching failure can be prevented as much as possible. Other effects similar to those of the third or fourth aspect are achieved.

  The sewing machine of the present embodiment is configured so that the lower thread fed from the bobbin case and supplied to the needle hole of the needle plate can be switched between the left route and the right route with respect to the vertical movement trajectory of the sewing needle. By switching the lower thread to either the left route or the right route depending on the direction, hitch stitching is prevented and perfect stitching is achieved.

  As shown in FIG. 1, a pattern sewing machine 1 includes a sewing machine table 2, a sewing machine body 3 mounted on the sewing machine table 2, an X direction (left-right direction) and a Y direction (front-rear direction) perpendicular to the work cloth. A cloth feeding mechanism 4 that feeds the cloth independently and an operation panel 5 are provided. The sewing machine body 3 includes a bed portion 6, a pedestal column portion 7, and an arm portion 8.

  The cloth feed mechanism 4 has a feed base (not shown) below the needle plate 9, a feed plate 12 fixed on the feed plate and disposed on the top surface of the needle plate 9, and curved upward and forward from the feed base. A presser arm 13 that extends in a shape and presses the work cloth on the upper surface of the feed plate 12, and an X-direction drive mechanism and a Y-direction drive mechanism that move and drive the feed base, the feed plate 12, and the presser arm 13 independently in the X and Y directions, Have

  The X-direction drive mechanism sends the rotation of the X-axis drive motor 14 (see FIG. 11) and the X-axis drive motor 14 to the X-direction feed of the feed base via a cylindrical helical cam (not shown) fixed to the output shaft. The Y-direction drive mechanism includes a Y-axis drive motor 15 (see FIG. 11) and a cylindrical helical cam fixed to the output shaft of the rotation of the Y-axis drive motor 15. And a mechanism (not shown) for converting to a Y-direction feed of the feed base via (not shown).

  In this pattern sewing machine 1, while the work cloth on the feed plate 12 is pressed and held by the presser arm 13, the feed base is moved in the X and Y directions by the drive motors 14 and 15 while the sewing needle 10 is reciprocated up and down. The pattern according to the sewing data is automatically sewn on the work cloth W by controlling the position in the two directions of the X direction and the Y direction. The operation panel 5 is provided with a liquid crystal display 5a, a numeric keypad 5b, switches 5c having various switches, and the like.

Next, the vertical full rotary hook 20 provided in the bed part 6 will be described.
As shown in FIGS. 2, 3, and 6, the vertical full rotary hook 20 is a full rotary hook for high-speed zigzag stitching, and includes an outer hook 21 provided rotatably around a horizontal rotation shaft, and an outer hook 21. And an inner hook 22 that is rotatably supported with respect to the outer hook 21, and a bobbin case 23 attached to the inner hook 22.

  The outer hook 21 has an outer hook main body 25 and a rotary shaft 26 connected to the outer hook main body 25. The lower shaft 11 that rotates in synchronization with the main shaft (not shown) is connected to the rotary shaft 26 via a coupling 27. When the rotational force is transmitted, it is rotated clockwise around the axis of the rotary shaft 26 in a front view in synchronization with the vertical movement of the sewing needle 10. Here, the outer hook body 25 is formed with a sword tip 25a oriented in the clockwise rotation direction.

  The inner hook 22 has an inner hook body 28 and a stud 29, is fitted coaxially to the outer hook body 25, and is supported rotatably with respect to each other. The stud 29 is provided so as to protrude from the bottom of the inner hook body 28 to the open end side of the inner hook body 28.

  As shown in FIG. 6, the bobbin case 23 is a cylindrical body whose front face is closed, and is attached to the inner hook 22 in a state in which relative rotation is prevented, and the lower thread around which the lower thread DT is wound. A bobbin (not shown) is accommodated. When the rotational force due to the rotation of the lower shaft 11 is transmitted to the vertical full rotary hook 20, the outer hook 21 is synchronized with the vertical movement of the sewing needle 10, and the inner hook 22 and the bobbin case 23 are prevented from rotating. Is driven to rotate clockwise.

  When the outer hook 21 is rotated, the upper thread UT extending from the eye hole 10a of the sewing needle 10 through which the work cloth W is inserted is captured by the sword tip 25a and circulates around the inner hook 22 so that the eye hole of the sewing needle 10 is obtained. The upper thread UT extending from 10a and the lower thread DT extending from the lower bobbin are entangled, and the upper thread loop is tightened by a balance (not shown) to form a stitch.

  As shown in FIG. 3, a thread tension spring 30 capable of adjusting the thread tension applied to the lower thread DT drawn out from the inner lower thread bobbin is provided on the right shoulder portion of the outer peripheral wall 23a of the bobbin case 23. It is attached. The lower thread DT exiting from the lower thread bobbin passes between the thread tension spring 30 and the outer peripheral wall 23 a, enters the outer peripheral wall 23 a from the tip of the thread tension spring 30, and is pulled out from the upper end of the bobbin case 23. . That is, the lower thread outlet 23b is formed on a substantially extended line of the vertical movement locus N of the sewing needle 10 (hereinafter simply referred to as the needle vertical movement locus N).

  Next, the lower thread supply route TR provided between the needle plate 9 and the vertical full rotary hook 20 and extending from the lower thread outlet 23b of the bobbin case 23 to the needle hole 9a of the needle plate 9 is set to the left route LR and the right route RR. The route switching mechanism 35 that switches alternatively to the above will be described.

  As shown in FIGS. 2 and 3, the route switching mechanism 35 (which corresponds to a switching unit) includes an engagement switching plate 36 (which corresponds to an engagement member) with which the lower thread DT of the lower thread supply path TR is engaged. ) And a switching cylinder 37 (which corresponds to an actuator) for selectively switching the engagement switching plate 36 between a left side position and a right side position.

  The engagement switching plate 36 is disposed in the left-right direction between the needle plate 9 and the vertical full rotary hook 20, and is located at the left position shown in FIGS. 2 and 3 and the right position shown in FIGS. It is guided to move in a horizontal position. In the vicinity of the right end of the engagement switching plate 36, a small engagement hole 36a is formed vertically. Therefore, the lower thread DT that exits from the lower thread outlet 23b of the bobbin case 23 passes through the engagement hole 36a from below and extends to the upper side of the needle plate 9 through the needle hole 9a of the needle plate 9.

  The switching cylinder 37 is a double-acting air cylinder and is connected to the left end portion of the engagement switching plate 36. Therefore, when the switching cylinder 37 is driven back and forth by the electromagnetic valve, the engagement switching plate 36 is switched to the left position shown in FIG. 2 and FIG. It is switched to the left route LR that is biased to the left. When the switching cylinder 37 is driven forward by the electromagnetic valve 58, the engagement switching plate 36 is switched to the right position shown in FIGS. 4 and 5, and the lower thread supply path TR is biased to the right with respect to the needle vertical movement locus N. To the right route RR.

  As stitches formed by pattern stitching, perfect stitches (see FIG. 7) in which the upper thread UT is entangled with the lower thread DT according to the stitch formation direction from each needle drop position to the next needle drop position, It is known that the hitch stitch (see FIG. 8) is entangled so that the upper thread UT is wound around the thread DT.

  In this pattern sewing machine 1, when the lower thread supply route TR is switched to the left route LR (see FIGS. 2 and 3) that is biased to the left with respect to the needle vertical movement locus N, a hitch stitch (see FIG. 8) is obtained. As shown in FIG. 9, the stitch formation direction range HSL with respect to the sewing needle 10 is 180 ° ≦ HSL ≦ 200 ° when the + Y direction of the XY coordinates is 0 °. However, other than the stitch formation direction range HSL, that is, 0 ° ≦ PSL <180 ° and 200 ° <PSL <360 ° are the stitch formation direction range PSL for the sewing needle 10 that is a perfect stitch.

  When the lower thread supply route TR is switched to the right route RR (see FIGS. 4 and 5) that is biased to the right with respect to the needle up-and-down movement locus N, the stitch formation direction range HSR for the stitch needle 10 that becomes a hitch stitch is As shown in FIG. 10, when the + Y direction of the XY coordinates is 0 °, 160 ° ≦ HSR ≦ 180 °. However, other than the stitch formation direction range HSR, that is, 0 ° ≦ PSR <160 ° and 180 ° <PSR <360 ° are the stitch formation direction range PSR for the sewing needle 10 that becomes a perfect stitch.

  As shown in FIG. 3, a detection plate 40 made of a substantially L-shaped metal plate is fixed to the lower portion of the left end portion of the engagement switching plate 36. A left switching detection switch 41 is provided to detect the detected plate 40 when the engagement switching plate 36 is switched to the left position, and the detected plate 40 is detected when the engagement switching plate 36 is switched to the right position. A right switching detection switch 42 is provided. These left and right switching detection switches 41 and 42 (which correspond to switching detection means) are each composed of proximity switches.

Next, the control system of the pattern sewing machine 1 will be described.
As shown in FIG. 11, the control device 45 includes a computer including a CPU 46, a ROM 47, a RAM 48, and the like. The control device 45 includes a start / stop switch 49, a presser switch 50 for switching the presser arm 13 between a presser position and a presser release position, a main shaft rotation angle detection sensor 51 for detecting the rotation angle of the sewing machine main shaft, and an operation A drive circuit 53 for the panel 5, a sewing machine motor 52, a drive circuit 55 for driving a presser solenoid 54 capable of switching the presser arm 13 to a presser position, and a drive circuit 56 for the X-axis drive motor 14. A drive circuit 57 for the Y-axis drive motor 15, an electromagnetic valve 58 for the switching cylinder 37, a left switching detection switch 41, and a right switching detection switch 42 are connected to each other.

  The ROM 47 stores in advance a plurality of sewing data for sewing a plurality of pattern patterns to be sewn, a control program for pattern sewing control unique to the present application for sewing these pattern patterns, and the like. Further, as shown in FIG. 12, the ROM 47 has a switching limit angle α ° for stopping the driving of the sewing machine motor 52 without switching the lower thread supply path TR by the switching cylinder 37 in the pattern sewing control. Is set as a parameter. The switching limit angle α ° indicates the rotation angle of the main shaft immediately before the sewing needle pierces the work cloth at the time of emergency stop at the current rotation speed of the sewing machine motor 52. The rotation angle of the spindle is 0 ° at the needle upper position and 180 ° at the needle lower position.

  This is because when the rotational speed of the sewing machine motor 52 is high, the switching limit angle α ° for determining whether the switching of the switching cylinder 37 is completed is small, that is, the sewing needle is changed to a higher position side. For example, when the rotational speed (sewing speed) of the sewing machine motor 52 is “2000 rpm”, the switching limit angle α ° is set to “106 °”.

  Further, in the ROM 47, as shown in FIG. 13, a switching start limit angle β °, which is a limit for starting the switching control, is set using the rotational speed (rpm) of the sewing machine motor 52 as a parameter. This prevents the sewing needle from being stuck in the work cloth while the switching cylinder 37 ends from the start of operation. Therefore, when the rotational speed of the sewing machine motor 52 is high, the switching start limit angle β ° is small, that is, the sewing needle. The sewing needle is changed to a lower position side before the needle position exceeds the higher position side or the upper needle position.

  For example, when the rotational speed (sewing speed) of the sewing machine motor 52 is “500 rpm”, the switching limit angle β ° is set to “40 °”. The RAM 48 is provided with memories (memory such as flags, pointers, and counters, registers, buffers, and the like) necessary for executing various controls as necessary.

  The sewing data of each pattern pattern is not shown, but stitches composed of X coordinate values and Y coordinate values for each of a number of needle drop positions from the first stitch to the final stitch, which are sewing start positions. It consists of data and sewing end code. However, each stitch data may be relative coordinate data or absolute coordinate data.

  Next, a pattern sewing control routine executed by the control device 45 will be described with reference to the flowcharts of FIGS. However, in the figure, reference sign Si (i = 11, 12, 13,...) Indicates each step.

  When the pattern sewing machine 1 is powered on, this control is started. First, at the start of sewing, when the sewing machine motor 52 is driven by operating the start / stop switch 49 (S11: Yes), the lower thread supply route TR The switching cylinder 37 is switched so that the left route LR becomes the left route LR (S12). Next, initial value “1” is set in the stitch counter (stitch count value I = 1) (S13), and the drive control of the sewing machine motor 52 is performed so as to reach a predetermined set speed (S14).

  Next, the I-th stitch data designated by the stitch count value I of the stitch counter is read (S15), and in the case of stitch data consisting of X-coordinate values and Y-coordinate values (S16: Yes). The stitch formation direction θ from the (I-1) th needle drop position to the needle drop position based on the I-th stitch data is calculated (S17). However, when the stitch count value I = 1 and the first stitch is formed, the stitch formation direction θ from the sewing start position toward the first stitch is calculated.

  Next, when the stitch formation direction θ obtained by the calculation belongs to the stitch formation direction range HSL that becomes the left hitch stitch (S18: Yes), the supply path flag NDF is set (data = 1). (S19), the process proceeds to S22. However, when the stitch formation direction θ obtained by the calculation belongs to the stitch formation direction range HSR that becomes the right hitch stitch (S18: No, S20: Yes), the supply path flag NDF is reset (data = 0). (S21), the process proceeds to S22.

  However, when the stitch formation direction θ obtained by the calculation does not belong to any of the stitch formation direction ranges HSL and HSR that become the left and right hitch stitches (S20: No), the X-axis drive motor 14 is After being driven, the Y-axis drive motor 15 is driven (S24), and the process proceeds to S30. Next, deceleration control is performed so that the rotation speed of the sewing machine motor 52 becomes a predetermined low speed (S22), and after the X-axis drive motor 14 is driven, the Y-axis drive motor 15 is driven (S23). Therefore, the work cloth is moved so that a stitch is formed at the next needle drop position.

  When the rotation angle of the main shaft is 150 ° or more and less than 360 °, or 0 ° or more and less than β °, that is, the lower thread DT and the sewing needle 10 intersect and the positional relationship of the lower thread DT with respect to the sewing needle 10 is If the supply path flag NDF is set (S26: Yes) when the switching is completed until the sewing needle pierces the work cloth even after the determination and the switching control is started (S25: Yes). The switching cylinder 37 is controlled so that the lower thread supply route TR becomes the right route RR (S27). However, when the supply path flag NDF is reset (S26: No), the switching cylinder 37 is switched so that the lower thread supply path TR becomes the left-side root LR (S31). In S25, when the rotation angle of the main shaft is not less than β ° and less than 150 ° (S25: No), even if the switching control is started from now on, the switching is not completed until the sewing needle pierces the work cloth. The drive is urgently stopped (S33).

  Next, when the switching cylinder 37 is switched so that the lower thread supply route TR becomes the right route RR, the lower thread supply route TR becomes the left route LR based on the switch signal from the right change detection switch 42. When the switching cylinder 37 is switched in such a manner, it is determined whether the lower thread supply route TR is switched to the right route RR or the left route LR based on the switch signal from the left switch detection switch 41 ( S28).

  If the switching is not completed (S28: No), and the main shaft rotation angle has not reached the switching limit angle α ° according to the rotational speed of the sewing machine motor 52 (S32: No), S26 to S28, S32 is repeatedly executed, and the switching command output to the switching cylinder 37 is repeated.

  When the lower thread supply route TR is switched to a different route (S28: Yes), drive control is performed so that the sewing machine motor 52 reaches the set speed (S29), and the stitch count value I is incremented by one. (S30), S15 and subsequent steps are repeatedly executed. When the data read up to the final stitch of the pattern pattern is not the stitch data consisting of the X coordinate value and the Y coordinate value but the sewing end code (S16: No), the sewing machine motor 52 Is stopped and this control is terminated.

  Incidentally, even if the main shaft reaches the switching limit angle α °, if the switching of the lower thread supply path TR is not completed (S28: No, S32: Yes), the drive of the sewing machine motor 52 is urgently stopped (S33), This control is terminated.

  The ROM 47 of the control device 45 corresponds to the stitch direction determining means, and the control device 45 that executes the pattern stitching control S17 corresponds to the stitch direction calculating means. The control device 45 that executes the pattern sewing control S18 and S20 corresponds to the discrimination means, and the control device 45 that executes the pattern sewing control S27 and S31 corresponds to the switching control means.

Next, a switching operation for switching the lower thread supply path TR so that each stitch does not become a hitch stitch according to the stitch formation direction will be described.
For example, as shown in FIG. 16, when pattern sewing is performed on the outer peripheral portion of a pentagonal applique cloth piece P over the work cloth W, the operator first places the work cloth W on the upper side of the needle plate 9 and then appliques the cloth. The piece P is placed over a predetermined sewing position. Then, the start / stop switch 49 is operated to drive the sewing machine motor 52, and pattern sewing is started at a sewing speed of about 300 rotations / minute. At this time, as an initial state, the engagement switching plate 36 is switched to the left position shown in FIGS. 2 and 3, so that the lower thread supply route TR is switched to the left route LR.

  In this case, first, when forming the stitches on the first sewing line L1, the stitch forming direction of each of the stitches S0 to S9 is either the stitch forming direction range HSL or HSR that becomes the left and right hitch stitches. Therefore, the stitches S0 to S9 are sequentially sewn with perfect stitches at a predetermined sewing speed (about 2000 revolutions / minute).

  However, when forming a stitch on the next second sewing line L2, the stitch forming direction of each of the stitches S10 to S18 belongs to the stitch forming direction range HSL that becomes the left hitch stitch. In this case, with the rotational speed of the sewing machine motor 52 decelerated to a low speed (for example, about 100 revolutions / minute), the engagement switching plate 36 has a spindle rotation angle of 150 ° or more and less than 360 °. When the angle is 0 ° or more and less than β °, the lower thread supply route TR is switched to the right route RR because the right position shown in FIGS. 4 and 5 is switched. Therefore, the stitch formation direction of each of the stitches S10 to S18 does not belong to the stitch formation direction range HSL that becomes the left hitch stitch, and each of the stitches S10 to S18 is sequentially sewn with a perfect stitch.

  When forming the stitches S19 to S27 of the third sewing line L3, the stitches S28 to S36 of the fourth sewing line L4, and the stitches S37 to S45 of the fifth sewing line L5, The stitch formation direction does not belong to any of the stitch formation direction ranges HSL and HSR that become the left and right hitch stitches. Accordingly, as in the case of sewing the first sewing line L1, the stitches S19 to S45 are sequentially sewn with perfect stitches at a predetermined sewing speed (about 2000 revolutions / minute).

  As described above, when the route switching mechanism 35 is switched, even when the sewing speed is high, the rotational speed of the sewing machine motor 52 is forcibly decelerated and the time until the sewing needle 10 pierces the work cloth W is extended. . Therefore, before the sewing needle 10 pierces the work cloth W, the lower thread supply route TR can be selectively switched between the left route LR and the right route RR. Therefore, regardless of the sewing speed, it is possible to reliably prevent hitch stitches from being produced and to sew with beautiful stitches only with perfect stitches.

  The route switching mechanism 35 includes an engagement switching plate 36 with which the lower thread DT of the lower thread supply path TR is engaged, and a switching cylinder 37 that selectively switches the engagement switching plate 36 between the left side position and the right side position. Therefore, the route switching mechanism 35 can be configured simply. Furthermore, the lower thread supply route TR can be quickly switched between the left route LR and the right route RR through the position switching of the engagement switching plate 36 by simply switching the driving of the switching cylinder 37.

  After outputting the lower thread supply path TR switching command, the switching of the engagement switching plate 36 is completed until the sewing needle 10 reaches the switching limit angle α ° based on the detection signals from the left and right switching detection switches 41 and 42. If not, the control device 45 stops the driving of the sewing machine motor 52. Accordingly, the operator can reliably recognize that the hitch stitch has occurred because the lower thread supply path TR cannot be switched in time due to the stop of the driving of the pattern sewing machine 1.

  In the switching control, as the rotational speed of the sewing machine motor 52 increases, the switching limit angle α ° is decreased, that is, the sewing needle 10 is changed to a higher state. Therefore, even if the sewing speed is high, the speed is low. In addition, it is possible to reliably prevent the hitch stitch from occurring due to the switching delay of the lower thread supply path TR.

  Further, in the switching control, when the switching detection switches 41 and 42 do not detect the completion of switching of the engagement switching plate 36, the switching command is repeatedly output until the switching limit angle α ° is reached. Failure can be prevented as much as possible.

Next, a modified embodiment in which the above embodiment is partially modified will be described.
1) An engagement hole 36 a is provided in the vicinity of the tip of the engagement switching plate 36, and the lower thread DT is engaged with the engagement hole 36 a, but an engagement notch is provided in the vicinity of the tip of the engagement switching plate 36. The lower thread DT may be engaged with the engagement notch. Also in this case, the same effect as the above-described embodiment can be obtained.

2) The switching timing of the lower thread supply path TR by the switching cylinder 37 may be obtained by calculation using the rotational speed of the sewing machine motor 52 as a parameter.

It is a perspective view of the pattern sewing machine which concerns on the Example of this invention. It is a fragmentary top view of a bed part when a lower thread supply path is a left route. It is a front view of a bed part when a lower thread supply route is a left route. FIG. 3 is a view corresponding to FIG. 2 when the lower thread supply route is a right route. FIG. 4 is a view corresponding to FIG. 3 when the lower thread supply route is a right route. It is a perspective view of a vertical full rotation hook. It is explanatory drawing of a perfect stitch. It is explanatory drawing of a hitch stitch. It is explanatory drawing explaining the left stitch formation direction range. It is explanatory drawing explaining the right stitch formation direction range. It is a block diagram of a control system of a pattern sewing machine. It is a diagram which shows the relationship between a rotational speed and a switching limit angle. It is a diagram which shows the relationship between a rotational speed and a switching start limit angle. It is a part of flowchart of pattern sewing control. It is the remainder of the flowchart of pattern sewing control. It is explanatory drawing which sews an applique cloth piece on a work cloth.

Explanation of symbols

1 pattern sewing machine 4 cloth feed mechanism 10 sewing needle 20 vertical full rotation hook 35 route switching mechanism 36 engagement switching plate 37 switching cylinder 41 left switching detection switch 42 right switching detection switch 45 controller 47 ROM
52 Sewing motor LR Left route RR Right route TR Lower thread supply route

Claims (5)

A sewing needle that is driven up and down by rotation of a main shaft driven by a sewing motor, a rotary hook that is rotated in conjunction with the rotation of the main shaft, and a cloth that independently feeds a work cloth in two different directions based on sewing data. In a sewing machine having a feeding means,
The lower thread supply path from the rotary hook to the needle hole of the needle plate can be selectively switched between a left-side route biased to the left side and a right-side route biased to the right side with respect to the vertical movement locus of the sewing needle. Switching means;
For each of the left route and the right route switched by the switching unit, a stitch direction setting unit that presets and stores a stitch formation direction range for a stitch needle that becomes a hitch stitch,
Stitch direction calculation means for calculating a stitch formation direction from each needle drop position to the next needle drop position based on stitch data for each needle drop position in the sewing data;
Determining means for determining whether or not the stitch formation direction calculated by the stitch direction calculating means belongs to a stitch formation direction range of the hitch stitch set by the stitch direction setting means;
If the stitch formation direction belongs to the stitch direction range set in the stitch direction setting means in response to the discrimination result of the discrimination means, the stitches are made into the hitch stitch after the rotational speed of the sewing machine motor is reduced. Switching control means for switching control of the switching means so as to become a perfect stitch,
A sewing machine characterized by comprising:   The switching means includes an engaging member with which a lower thread of a lower thread supply path is engaged, and an actuator that selectively switches the engaging member between a left position and a right position. The described sewing machine.   The switching control means includes switching detection means for detecting completion of switching of the engaging member by the actuator, and after outputting a lower thread supply path switching command, the switching detecting means switches the engagement member. The sewing machine according to claim 2, wherein when the completion is not detected, the driving of the sewing machine motor is stopped when the sewing needle is equal to or larger than a switching limit angle that is a predetermined angle of the main shaft.   4. The sewing machine according to claim 3, wherein the switching control unit changes the switching limit angle to be smaller as the rotational speed of the sewing machine motor increases.   5. The switching control means repeatedly outputs the switching command until the switching limit angle is reached when switching completion of the engaging member is not detected by the switching detection means. Sewing machine.

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