Acquisition device and two-needle sewing machine

Abstract

To easily acquire parameters for corner sewing control.SOLUTION: An acquisition device comprises: an upstream additional seam acquisition unit 911 that acquires ideal length IL of an upstream additional seam from a bent angle A and a sewing width W of two seams; an upstream correction length acquisition unit 912 that determines an upstream correction sewing pitch IP and the number of upstream needles IN based on the ideal length IL; a downstream additional seam acquisition unit 913 that acquires ideal length OL of a downstream additional seam on a downstream side of an apex of a bent part of a seam on the outer side; and a downstream correction length acquisition unit 914 that determines a downstream correction sewing pitch OP and a number of downstream needles ON based on the ideal length OL of the downstream additional seam.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to an acquisition device for acquiring corner stitching parameters for a twin-needle sewing machine, and to a twin-needle sewing machine. [Background technology]

[0002] BACKGROUND ART Twin-needle sewing machines have been used in the past, which are equipped with two sewing needles and can selectively perform twin-needle sewing, in which two parallel stitches are formed, and single-needle sewing, in which a single sewing needle is used. For example, as shown in Figure 9, when two parallel stitches are formed along a path that bends at a bend, an additional upstream stitch Su and an additional downstream stitch Sd are formed upstream and downstream of the apex of the bend of the outer stitch, respectively, in excess of the inner stitch. For this reason, in a conventional twin-needle sewing machine, twin-needle sewing is performed until just before the upstream additional stitch Su is reached, then switching to single-needle sewing at the start position of forming the upstream additional stitch Su and single-needle sewing is performed up to the apex of the bend. Furthermore, the sewing machine is stopped in a single-needle needle entry state at the apex of the bend, the workpiece is rotated according to the bending angle A, then the downstream additional stitch Sd is formed with single-needle sewing, and twin-needle sewing is resumed at the end position of the downstream additional stitch Sd (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-177077 [Patent Document 2] Patent No. 2569215 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, when forming two parallel stitches along a path that bends at a bend, the lengths of the upstream additional stitch Su and the downstream additional stitch Sd, as well as the stitch pitch and number of stitches for the upstream additional stitch Su and the downstream additional stitch Sd, must be determined, which increases the workload.

[0005] An object of the present invention is to easily adjust the stitch pitch and number of stitches of the upstream additional stitches and the downstream additional stitches. [Means for solving the problem]

[0006] The present invention provides An acquisition device for acquiring corner stitching parameters for a twin-needle sewing machine that holds two sewing needles and is capable of selectively performing twin-needle sewing, which holds two sewing needles and forms two parallel stitches, or single-needle sewing, which uses a single sewing needle, and a feed mechanism that feeds a workpiece on a needle plate at an arbitrary set stitch pitch in synchronization with the needle bar mechanism, and that forms the two parallel stitches at a constant interval by bending each of the two stitches at the same bending angle based on the set stitch pitch, an upstream additional stitch obtaining unit that obtains an ideal length of an upstream additional stitch that is formed upstream of the apex of the bend of the outer stitch and in excess of the inner stitch, based on the bend angle and the stitch width of the two stitches; an upstream-side corrected length acquisition unit that determines an upstream-side corrected stitch pitch and the number of upstream stitches by correcting the set stitch pitch based on the ideal length of the upstream-side additional stitch; a downstream additional stitch obtaining unit that obtains an ideal length of a downstream additional stitch that is formed downstream of the apex of the bend of the outer stitch and in excess of the inner stitch; and a downstream side corrected length acquisition unit that determines the downstream side corrected stitch pitch and the downstream side number of stitches by correcting the set stitch pitch based on the ideal length of the downstream side additional stitch.

[0007] Another aspect of the present invention is A twin-needle sewing machine is provided with a needle bar mechanism that holds two sewing needles and is capable of selectively performing twin-needle sewing, which forms two parallel stitches, and single-needle sewing with one sewing needle, and a feed mechanism that feeds an object to be sewn on a needle plate at an arbitrary set stitch pitch in synchronization with the needle bar mechanism, and forms the two parallel stitches with a constant stitch width by bending each of the two stitches at the same bending angle based on the set stitch pitch, an acquisition device having the above configuration; The corner stitching device is characterized by comprising a corner stitching control unit that controls the needle bar mechanism and the feed mechanism based on the corner stitching parameters acquired by the acquisition device. [Effects of the Invention]

[0008] According to the present invention, it is possible to easily adjust the stitch pitch and the number of stitches of the upstream additional stitches and the downstream additional stitches. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the overall configuration of a twin-needle sewing machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of a needle bar mechanism included in the twin-needle sewing machine. [Figure 3] FIG. 2 is a perspective view showing a switching lever that manually switches a switching member between a left / right switching position and a neutral position. [Figure 4] FIG. 2 is a block diagram showing a control system of a twin-needle sewing machine. [Figure 5] FIG. 10 is a diagram showing an input screen for selecting and setting the number of individual bent portions to be sewn in corner stitching control sewing. [Figure 6] FIG. 10 is a diagram showing an input screen for setting the value of the bending angle of a bending portion. [Figure 7] FIG. 10 is an explanatory diagram showing the parameter acquisition process in the process (1) for acquiring derived parameters for corner stitching. [Figure 8] 8 is an explanatory diagram following FIG. 7 showing the parameter acquisition process in the process (1) for acquiring derived parameters for corner stitching. [Figure 9]9 is an explanatory diagram following FIG. 8 showing the parameter acquisition process in the process (1) for acquiring derived parameters for corner stitching. [Figure 10] 10 is a flowchart showing corner stitching control executed by a corner stitching control unit. [Figure 11] FIG. 10 is an explanatory diagram showing a stitch in which the “beak” phenomenon occurred in the process (1) for obtaining derived parameters for corner stitching. [Figure 12] FIG. 10 is an explanatory diagram showing a stitch in which a "clogging" phenomenon occurred in the process (1) for obtaining derived parameters for corner stitching. [Figure 13] FIG. 10 is an explanatory diagram showing the parameter acquisition process in the process (2) of acquiring derived parameters for corner stitching. [Figure 14] 14 is an explanatory diagram following FIG. 13 showing the parameter acquisition process in the process (2) of acquiring derived parameters for corner stitching. FIG. [Figure 15] 14A to 14C are explanatory diagrams illustrating the parameter acquisition process in the process (2) for acquiring derived parameters for corner stitching. [Figure 16] 15A to 15C are explanatory diagrams illustrating the parameter acquisition process in the process (2) for acquiring derived parameters for corner stitching. [Figure 17] 10 is a table showing a list of individual combinations of all candidate values ​​for the upstream correction stitch pitch and all candidate values ​​for the number of upstream stitches based on specific numerical examples. [Figure 18] 10 is a table showing a list of individual combinations of all candidate values ​​for the downstream side correction stitch pitch and all candidate values ​​for the downstream side stitch count based on specific numerical examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Overall configuration of the embodiment of the invention] A twin-needle sewing machine 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 18. Figure 1 is a schematic diagram showing the overall configuration of the twin-needle sewing machine 100. In the following description, it is assumed that the twin-needle sewing machine 100 is installed on a horizontal plane, and the vertical direction is defined as the Z-axis direction, the direction along the feed direction of the workpiece on the horizontal plane is defined as the X-axis direction, and the direction perpendicular to the X-axis direction on the horizontal plane is defined as the Y-axis direction. Note that the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. FIG. 1 shows a state in which a twin-needle sewing machine 100 is placed on a table 2 that serves as a work table.

[0011] The twin-needle sewing machine 100 comprises two needle bars 20 which individually hold two sewing needles 7, a needle bar mechanism 10 which moves each needle bar 20 up and down in a double-needle state or in a single-needle state using one of the selected sewing needles 7, a feed device which transports the workpiece on the table 2 at a set stitching pitch, a shuttle mechanism, and a sewing machine frame 9 which holds the above components. The twin-needle sewing machine 100 also has common components that are found in all sewing machines, such as a thread tensioning device, a thread cutting device, a presser foot for the sewing material, and a thread take-up lever, but since these are well-known structures, they will not be shown or described here.

[0012] [Needle bar mechanism] 2 is a front view of the needle bar mechanism 10. The needle bar mechanism 10 is provided within the surface portion at the tip of the arm portion of the sewing machine frame 9, and simultaneously or selectively moves up and down a pair of needle bars 20, each of which individually holds two sewing needles 7. This allows the needle bar mechanism 10 to perform double needle stitching, which forms two stitches, and single needle stitching, which forms a single stitch. When performing single needle stitching, either of the two needle bars 20 can be selected.

[0013] The needle bar mechanism 10 comprises a pair of needle bars 20 aligned in the Y-axis direction, a needle bar support frame 40 as a needle bar support that supports each needle bar 20 so that it can move up and down individually, a needle up / down movement mechanism 50 that moves each needle bar 20 up and down via a needle bar holder 51 that holds the pair of needle bars 20, a clutch mechanism 60 that can switch between holding and releasing each needle bar 20 by the needle bar holder 51, a stopper mechanism 70 that holds a needle bar 20 that has been released from holding by the clutch mechanism 60 in the needle raised position, and a switching mechanism 80 that selects one of the needle bars 20 and switches between a held state and a released state in the clutch mechanism 60.

[0014] The needle bar support frame 40 supports the two needle bars 20 so that they can move up and down individually. A stopper mechanism 70 is provided above the needle bar support frame 40, and a switching mechanism 80 is provided immediately below that.

[0015] As shown in FIG. 2, the needle up / down movement mechanism 50 includes a needle bar holder 51 that holds two needle bars 20, a sewing machine main shaft 52 that is driven to rotate by the sewing machine motor 11 (see FIG. 4), a rotating spindle 53 fixed to one end of the sewing machine main shaft 52, a crank rod 54 that connects the rotating spindle 53 and the needle bar holder 51, and a square piece 55 that moves the lower end of the crank rod 54 along the Z-axis direction. With this configuration, the needle up / down movement mechanism 50 can use the sewing machine motor 11 as a drive source to move each needle bar 20 held by the needle bar holder 51 up and down relative to the needle bar support frame 40 via the clutch mechanism 60.

[0016] The clutch mechanism 60 holds the needle bars 20 by inserting two clutch members 61 provided on the needle bar holder 51 into engaging holes formed in each needle bar 20 under spring pressure. The clutch mechanism 60 also has two link members 62 that release the clutch members 61 from their engaged state when they collide with protrusions 81a of the switching member 81 of the switching mechanism 80 as the needle bar holder 51 rises.

[0017] The stopper mechanism 70 includes a stopper member that fits into a recess provided above the engagement hole of the clutch member 61 in each needle bar 20 . Each needle bar 20 has a built-in lever member (not shown) inside, and when the clutch member 61 of the clutch mechanism 60 is engaged with the engagement hole, the lever action closes the recess and prevents the stopper member from fitting. When the protrusion 81a of the switching member 81 of the switching mechanism 80 collides with the link member 62 and the clutch member 61 is disengaged, the lever member rotates to open the recess, and the stopper member fits into the recess, thereby holding the needle bar 20 in the raised position. In other words, the needle bar 20 is released from the state in which it is held by the clutch member 61 relative to the needle bar holder 51, and is held in the raised position by the stopper mechanism 70, preventing it from moving up and down. As a result, a single stitch is formed using only the needle bar 20 that is not held by the stopper mechanism 70.

[0018] The switching mechanism 80 includes a switching member 81 that can be moved to three positions: two switching positions where the protrusion 81a collides individually with the two link members 62 of the clutch mechanism 60, and a neutral position where it does not collide with either of the two switching positions; and a solenoid 82 that moves the switching member 81 to the neutral position. The operation of the solenoid 82 is controlled by the control device 90 via a drive circuit 822 . FIG. 2 shows a state in which the switching member 81 is in a neutral position, with the left side of the neutral position being one switching position and the right side of the neutral position being the other switching position.

[0019] The two switching positions of the switching member 81 are positions that release the respective holding states of the two needle bars 20 by the clutch mechanism 60, and the neutral position is a position where the protrusion 81a of the switching member 81 collides with the release pin 66 of the clutch mechanism 60. The release pin 66 is a member that returns the two clutch members 61, which have been released from their holding states, to their holding states again. When the switching member 81 is in the neutral position, both of the two needle bars 20 are held by the needle bar holder 51. Therefore, when the switching member 81 is in the neutral position, double-needle sewing is performed, when it is in the switching position to the left of the neutral position, single-needle sewing is performed on the right side by the sewing needle 7 held by the right needle bar 20, and when it is in the switching position to the right of the neutral position, single-needle sewing is performed on the left side.

[0020] FIG. 3 is a perspective view showing a switching lever 83 that is manually operated to switch the switching member 81 between the left / right switching position and the neutral position. The switching lever 83 is provided on the operator side (the front side of the paper in FIG. 1) near the tip of the sewing machine arm portion of the sewing machine frame 9. The switching lever 83 imparts a moving action to the switching member 81 via a plurality of transmission members. When the switching lever 83 is operated to the left, the switching member 81 moves to the right, and when the switching lever 83 is operated to the right, the switching member 81 moves to the left. Therefore, when the switching lever 83 is operated to the left, single needle sewing on the left side is performed, and when operated to the right, single needle sewing on the right side is performed.

[0021] In addition, the switching lever 83 is provided with a return spring (not shown) that presses the switching lever 83 from the left and right to return it to the neutral position, and a maintenance mechanism (not shown) that mechanically maintains the position of the switching lever 83 after it is operated to the left or right. Furthermore, the switching mechanism 80 is equipped with a solenoid 82 (see Figure 4) that releases the mechanically maintained state of the switching lever 83, and can release the position of the switching lever 83 maintained by the maintenance mechanism after operation in accordance with the control of the control device 90. The switching lever 83 is also provided with a switching lever sensor 84 for detecting whether the switching lever 83 is in the left or right operating position or in the neutral position for double needle stitching. Therefore, the twin-needle sewing machine 100 can be manually switched to either the left or right single needle sewing state, and can be switched from the single needle sewing state to the double needle sewing state under the control of the control device 90.

[0022] [Shuttle mechanism] A shuttle mechanism (not shown) is provided below the needle plate where the two sewing needles 7 penetrate. The shuttle mechanism has two horizontal shuttles arranged in parallel in the Y-axis direction, one for each of the two sewing needles 7. Furthermore, the shuttle mechanism receives power from the sewing machine motor and rotates each horizontal shuttle at twice the speed of the sewing machine main shaft 52.

[0023] [Feed mechanism] The feed mechanism is provided below the needle plate and receives power from a lower shaft that is driven to rotate by the sewing machine motor 11 as a drive source, and synchronously applies reciprocating motion along the X-axis direction and the Z-axis direction to the feed dog. As a result, the feed dog moves circularly along an oval feed locus, and as it moves along the feed direction on the feed locus, the feed dog comes into contact with the underside of the workpiece, enabling the workpiece to be intermittently fed at a constant stitching pitch.

[0024] The feed mechanism also includes a feed adjustment motor 12 (see FIG. 4) that operates a plurality of transmission members that impart reciprocating motion along the X-axis direction from the lower shaft to the feed dog, thereby changing the amplitude of the reciprocating motion along the X-axis direction. This feed adjustment motor 12 is controlled by a control device 90, and can adjust the amplitude of the reciprocating motion along the X-axis direction imparted to the feed dog, thereby adjusting the stitch pitch to any desired value. These components, including the feed adjustment motor 12, make up the feed adjustment mechanism. In practice, the control device 90 is capable of adjusting the stitch pitch in increments of 0.1 mm.

[0025] [Control device] 4 is a block diagram showing the control system of twin-needle sewing machine 100. Twin-needle sewing machine 100 is equipped with a control device 90 as control means for controlling the operation of each of the above-mentioned parts. Control device 90 is equipped with a ROM 92 in which a basic program for overall control of the entire sewing machine is stored, a RAM 93 which serves as a work area for arithmetic processing, a non-volatile data memory 94 as storage means for storing various programs and various data such as sewing data, and a CPU 91 which executes the programs in ROM 92.

[0026] The CPU 91 is also connected to a sewing machine motor drive circuit 111 and a feed adjustment motor drive circuit 121 via an interface (not shown), and controls the driving of the sewing machine motor 11 and the feed adjustment motor 12 via these. The sewing machine motor 11 is a servo motor equipped with an encoder (not shown), and the detected angle is output to the CPU 91. Further, the feed adjusting motor 12 is a stepping motor, and origin retrieval means (not shown) for this is connected to the CPU 91, and the CPU 91 can recognize the origin position of the feed adjusting motor 12 from its output.

[0027] The CPU 91 is also connected to the switching lever sensor 84 of the switching mechanism 80 described above via an interface (not shown). Furthermore, the CPU 91 is connected to the solenoid 82 of the switching mechanism 80 via a drive circuit 822 .

[0028] An operation input device 95 is also connected to the CPU 91 via an interface (not shown). The operation input device 95 includes, for example, a touch sensor 96 as an input unit and a display panel 97 as a display unit. The display panel 97 is made up of a display device such as a liquid crystal or organic EL display, and the touch sensor 96 is attached to the display screen of the display panel 97. The touch sensor 96 has a function of detecting a contact position on the display screen of the display panel 97.

[0029] An operation key group having various keys and buttons, various sewing data, and various input screens are displayed on the display panel 97. When the operator performs a touch operation on the operation key group or various input screens displayed on this display panel 97, the touch sensor 96 detects the operation, and various settings from the operator are input to the operation input device 95.

[0030] An operation pedal 3 is also connected to the CPU 91 via an interface (not shown). Operations such as starting and stopping sewing with the twin needle sewing machine 100, lifting the presser foot of the sewing material, and thread trimming are input from the operation pedal 3.

[0031] [Configuration for corner stitching control] In order for the control device 90 to execute the corner stitching control (see FIG. 10) described later, the operator inputs settings for the bending angle A of the bending portion where the corner stitching is performed, the stitch width W which is equal to the distance between the two sewing needles 7 in the Y-axis direction, and the set stitch pitch P during sewing through the operation input device 95. The corner stitching control is an operation control for forming two parallel stitches at a constant interval (stitch width W) by bending each of the stitches at the same bending angle A.

[0032] The stitch width W can be adjusted by replacing the needle presser (not shown) that holds the sewing needle 7 at the lower end of each needle bar 20. The operator installs a needle presser that will provide the desired stitch width W at the lower end of each needle bar 20, and inputs the value of the stitch width W into the control device 90.

[0033] The CPU 91 executes an acquisition program (not shown) stored in the data memory 94 to acquire derived parameters necessary for the corner stitch control from the setting parameters set by the operator. As a result, the CPU 91 functions as an upstream additional stitch acquisition unit 911, an upstream correction length acquisition unit 912, a downstream additional stitch acquisition unit 913, and a downstream correction length acquisition unit 914, and the CPU 91 functions as an acquisition device that executes an acquisition method to acquire derived parameters necessary for corner stitching control.

[0034] The derived parameters necessary for the corner stitching control include the number of upstream stitches IN of the upstream additional stitch Su, the upstream correction stitch pitch IP of the upstream additional stitch Su, the ideal length IL of the upstream additional stitch Su, the number of downstream stitches ON of the downstream additional stitch Sd, the downstream correction stitch pitch OP of the downstream additional stitch Sd, and the ideal length OL of the downstream additional stitch Sd.

[0035] First, the input of the number of bent portions, the bent angle A, the stitch width W, and the set stitch pitch P from the operation input device 95 by the operator will be described. 5 shows an input screen G1 for selecting and setting the number of individual bent portions to be sewn in corner stitching control sewing. This input screen G1 is displayed on the display panel 97 of the operation input device 95. This input screen G1 displays selection buttons B1 to B5 for selecting the number of individual bent portions for which corner stitching control is to be performed (1 to 5), a selection button B0 for performing sewing by manual operation without corner stitching control, and a confirmation button B6 for confirming the settings. On this input screen G1, the number of individual bent portions is limited to 5, but this number is just an example and a larger number may be selectable.

[0036] When one or more bent portions are selected as the number of bent portions for which corner stitching control is to be performed on the input screen G1, the setting parameters for corner stitching control, such as the bending angle A, stitch width W, and set stitch pitch P, can be set for each bent portion. Furthermore, when these setting parameters are set, the control device 90 derives the aforementioned derived parameters. Then, the control device 90 determines the above-mentioned setting parameters and the above-mentioned derived parameters for each of one or more bent portions included in the series of stitches, and sewing data recording all of these setting contents is stored in the data memory 94. The term "series of sewing" refers to a single continuous sewing operation that includes a set number of bent portions. The data memory 94 can store multiple pieces of sewing data, and each piece of sewing data is recorded with an identifier that identifies it. This allows the twin-needle sewing machine 100 to select one piece of sewing data from the multiple pieces of sewing data and perform corner stitching control.

[0037] The stitch width W and the set stitch pitch P can be set from an input screen (not shown) displayed on the display panel 97. Numeric keys and a confirm button are displayed on the input screens for the stitch width W and the set stitch pitch P, respectively, for inputting the set value of the stitch width W or the set stitch pitch P. Note that, instead of the numeric keys, selection buttons for selecting a plurality of setting values ​​to be selected may be displayed, or keys for increasing or decreasing the numerical value may be displayed. The stitch width W can be set in units of 1 mm, for example, and the set stitch pitch P can be set in units of 0.1 mm, for example.

[0038] 6 shows an input screen G2 for setting the value of the bending angle A of the bending portion. This input screen G2 is displayed on the display panel 97 of the operation input device 95. This input screen G2 displays increase / decrease keys B11 and B12 for setting the planned bending angle A of the bending portion for which corner stitching control is to be performed, and a confirmation button B15 for confirming the setting. The bending angle A relative to the path may be set to a value in the range of 0 to 180°, and whether the bending is to the left or right relative to the path may be set separately. The bending angle may also be set to a value in the range of 0 to 360°. In this case, it is necessary to specify whether the bending is to be performed clockwise or counterclockwise relative to the path.

[0039] Furthermore, this input screen G2 displays a numerical display field W1 for the currently input bending angle, and numerical display fields W2 to W7 for the number of upstream stitches IN of the upstream additional stitch Su, the upstream correction stitch pitch IP of the upstream additional stitch Su, the ideal length IL of the upstream additional stitch Su, the downstream number of stitches ON of the downstream additional stitch Sd, the downstream correction stitch pitch OP of the downstream additional stitch Sd, and the ideal length OL of the downstream additional stitch Sd, which are calculated or acquired by the control device 90 for performing corner stitching control. These display fields W2 to W7 display the values ​​of the upstream stitch count IN of the upstream additional stitch Su, the upstream correction stitch pitch IP of the upstream additional stitch Su, the ideal length IL of the upstream additional stitch Su, the downstream stitch count ON of the downstream additional stitch Sd, the downstream correction stitch pitch OP of the downstream additional stitch Sd, and the ideal length OL of the downstream additional stitch Sd, which are acquired by the process (1) or (2) of acquiring the derived parameters for corner stitching, which will be described later. When performing the process (2) for obtaining the derived parameters for corner stitching, the display fields W4 and W7 may display the corrected length ILC of the upstream additional stitch Su and the corrected length OLC of the downstream additional stitch Sd, respectively.

[0040] Furthermore, this input screen G2 displays adjustment keys B13 and B14 for adjusting the values ​​of the upstream stitch count IN of the acquired upstream additional stitch Su, the upstream correction stitch pitch IP of the upstream additional stitch Su, the downstream stitch count ON of the downstream additional stitch Sd, and the downstream correction stitch pitch OP of the downstream additional stitch Sd. When making an adjustment, one of the display fields W2, W3, W5, and W6 is selected by touch operation, and then the respective values ​​are adjusted using the adjustment keys B13 and B14.

[0041] In other words, the control device 90 can adjust the values ​​of the upstream stitch count IN of the upstream additional stitch Su, the upstream correction stitch pitch IP of the upstream additional stitch Su, the downstream stitch count ON of the downstream additional stitch Sd, and the downstream correction stitch pitch OP of the downstream additional stitch Sd, which are acquired by the process (1) or (2) for acquiring the derived parameters for corner stitching, and can generate sewing data with the values ​​after some or all of the derived parameters have been adjusted, and register it in the data memory 94. Therefore, by selecting the sewing data, corner stitching can be performed in accordance with the adjusted derived parameters.

[0042] [Processing to obtain derived parameters for corner stitching (1)] The following describes an acquisition process (1) that realizes a method for acquiring each derived parameter derived based on each set parameter by the CPU 91 of the control device 90. This acquisition process (1) is realized by cooperation of an upstream added stitch acquisition unit 911, an upstream correction length acquisition unit 912, a downstream added stitch acquisition unit 913, and a downstream correction length acquisition unit 914 of the CPU 91.

[0043] 7 to 9 are explanatory diagrams showing the sequence of steps for obtaining parameters in the process (1) for obtaining derived parameters for corner stitching. Arrow C in Figs. 7 to 9 indicates the direction in which a stitch, which is the sewing path, is formed (the direction opposite to the feed direction of the sewing workpiece).

[0044] 7 to 9, corner stitching at a bent portion involves first forming two parallel, linear stitches Sp using double needle stitching on the upstream side of the bent portion in the stitch forming direction C. The needle drop positions of these two stitches Sp are indicated by black dots. Next, while maintaining the course, an additional upstream stitch Su is formed by single-needle stitching on the outside (the stitch on the opposite side of the course taken by the bend in the bend) up to the apex of the bend. The needle points in the additional upstream stitch Su are shown by hatched dots. Furthermore, at the needle point position that is the apex of the bend, the path is bent at a bending angle A to form a downstream additional stitch Sd consisting of a single stitch on the outside. The needle points of the downstream additional stitch Sd are shown as white dots. Then, while maintaining its course, the stitching returns to double-needle stitching, forming two parallel, straight stitches Sp. At this time, the inner stitch resumes formation in the direction bent at bending angle A from the end point of the double-needle stitching before bending. The needle entry points for these two stitches Sp are shown as black dots.

[0045] In order to perform the corner stitching, the upstream additional stitch obtaining unit 911 derives the ideal length IL of the upstream additional stitch Su (upstream additional stitch obtaining step). 7, the ideal length IL of the upstream additional stitch Su corresponds to the length of the side adjacent to the vertex of a right triangle, which forms an angle of A / 2. The length of the opposite side of this right triangle matches the stitch width W, so the upstream additional stitch acquisition unit 911 can acquire the ideal length IL of the upstream additional stitch Su from the following equation. IL=W / tan(A / 2)

[0046] Next, the upstream correction length acquisition unit 912 determines the upstream correction stitch pitch IP and the upstream stitch count IN from the ideal length IL of the upstream additional stitch Su (upstream correction length acquisition step). The upstream correction length acquisition unit 912 derives the number of upstream stitches IN by dividing the ideal length IL of the upstream additional stitch Su by the set stitch pitch P. Since the number of upstream stitches IN must be an integer, the divided value is rounded off to the first decimal place. IN=IL / P

[0047] Furthermore, the upstream correction length acquisition unit 912 derives the upstream correction stitch pitch IP by dividing the ideal length IL of the upstream additional stitch Su by the derived upstream stitch count IN. Since the resolution for setting the stitch pitch is 0.1 mm, the divided value is rounded off to one decimal place. IP=IL / IN

[0048] On the other hand, the downstream side additional stitch obtaining unit 913 derives the ideal length OL of the downstream side additional stitch Sd (downstream side additional stitch obtaining step). As shown in Figure 7, the ideal length OL of the downstream additional stitch Sd also corresponds to the length of the adjacent side to the vertex at angle A / 2 of the right triangle, so in the same way as the ideal length IL of the upstream additional stitch Su, the ideal length OL of the downstream additional stitch Sd can be obtained using the following equation. OL=W / tan(A / 2)

[0049] Furthermore, the downstream side correction length acquisition unit 914 determines the downstream side correction stitch pitch OP and the downstream side stitch count ON from the ideal length OL of the downstream side additional stitch Sd (downstream side correction length acquisition step). The number of downstream stitches ON is calculated by dividing the ideal length OL of the downstream additional stitch Sd by the set stitch pitch P. In this case, the number of downstream stitches ON is also determined by rounding off the divided value to one decimal place. ON=OL / P

[0050] In addition, the downstream correction length acquisition unit 914 divides the ideal length OL of the downstream additional stitch Sd by the derived downstream stitch count ON, and rounds off the divided value to one decimal place to derive the downstream correction stitch pitch OP. OP=OL / ON

[0051] These allow the CPU 91 to obtain the derived parameters. The CPU 91 obtains derived parameters for each bent portion based on the setting parameters set for each bent portion, generates sewing data for a series of stitches, and registers the data in the data memory 94.

[0052] [Corner stitching operation control] The CPU 91 acquires the setting parameters and derived parameters for corner stitching and generates the sewing data, and can then execute corner stitching control based on the sewing data. That is, the CPU 91 executes a corner stitch control program (not shown) stored in the data memory 94. As a result, the CPU 91 functions as a corner stitching control unit 916 and executes corner stitching control. The corner stitching control executed by the corner stitching control unit 916 will be described with reference to the flowchart shown in FIG.

[0053] In the initial stage of corner stitch control, the switching lever 83 is in the neutral position. The corner stitching control unit 916 then reads the stitching data from the data memory 94 (step S1), and controls the feed adjusting motor 12 so that the stitch pitch becomes the set stitch pitch P determined in the stitching data (step S3).

[0054] Next, the corner stitching control unit 916 determines whether or not a sewing start command has been input from the operation pedal 3 (step S5), and if no command has been input, repeats the determination. On the other hand, when a sewing start command is input, the corner stitching control unit 916 lowers the presser foot that presses down on the sewing workpiece (not shown) and starts the sewing machine motor 11 to start double-needle sewing (step S7). That is, as shown in Figure 7, two parallel, straight stitches Sp are formed by double-needle sewing.

[0055] Next, the corner stitching control unit 916 determines whether or not a sewing stop command has been input from the operation pedal 3 (step S9), and if no input has been input, the process returns to step S7 to continue double needle sewing. Furthermore, when a sewing stop command is input from the operation pedal 3, the corner stitching control unit 916 stops the sewing machine motor 11 (step S11), and determines, using the switching lever sensor 84, whether the operator has switched the switching lever 83 to the left or right single-needle stitching position (step S13).

[0056] If a switch to single-needle stitching is not detected, the corner stitching control unit 916 determines whether or not a command to resume double-needle stitching has been input from the operating pedal 3 (step S15), and if a command to resume has been input, the process returns to step S9 and double-needle stitching is resumed. If the command to resume double-needle stitching is not input, the corner stitching control unit 916 returns the process to step S13 and again determines whether or not the switching lever 83 has been switched to the position for single-needle stitching.

[0057] Then, in step S13, when the switching lever sensor 84 detects that the switching lever 83 has been switched to single-needle stitching, the corner stitching control unit 916 controls the feed adjusting motor 12 so that the upstream correction stitch pitch IP is obtained (step S17).

[0058] Furthermore, the corner stitching control unit 916 starts the sewing machine motor 11 and performs single-needle stitching for the number IN of stitches on the upstream side (step S19). At the final stitch of this single-needle stitching, the sewing machine motor 11 is stopped at a position where the needle 7 is in the needle drop state, and the presser foot is raised (step S21). That is, as shown in FIG. 8, an additional upstream stitch Su consisting of a single outer stitch is formed up to the apex of the bent portion.

[0059] With the single needle stitching stopped in this needle drop state, the operator turns the workpiece by the bending angle A. This changes the path of the single needle stitching by the bending angle A. During this time, the corner stitching control section 916 waits for detection of an input from the operator via the operation pedal 3 to restart sewing (step S23).

[0060] When a command to resume sewing is input, the corner stitching control unit 916 controls the feed adjusting motor 12 so that the downstream correction stitch pitch is OP (step S25), lowers the presser foot, and starts the sewing machine motor 11 to perform single-needle sewing for the downstream stitch count ON (step S27). As a result, as shown in FIG. 9, the course is changed in the direction of the bending angle A from the position that is the apex of the bending portion, and a downstream side additional stitch Sd consisting of a single stitch on the outside is formed.

[0061] Next, the corner stitching control section 916 controls the solenoid 82 to release the single needle stitching state (step S29), and performs double needle stitching while maintaining the course (step S31). As a result, as shown in FIG. 9, two parallel, straight stitches Sp are formed by double needle stitching on the downstream side of the downstream additional stitch Sd.

[0062] Next, the corner stitching control unit 916 determines whether the next bend portion is set in the sewing data (step S33), and if the next bend portion is set, returns the processing to step S9 and performs corner stitching based on the set parameters and derived parameters set for the next bend portion. On the other hand, if the next bent portion is not set in the sewing data, the corner stitching control unit 916 determines whether or not the operator has input a command to stop sewing from the operation pedal 3 (step S35). At this time, the corner stitching control unit 916 continues double needle sewing unless an input to stop sewing is received, and if an input to stop sewing is received, stops the sewing machine motor 11, raises the presser foot, and ends corner stitching control.

[0063] [Processing to obtain derived parameters for corner stitching (2)] The above-described acquisition process (1) has the following problems. As shown in FIG. 11, depending on the values ​​of the upstream stitch count IN and the upstream correction stitch pitch IP, which are determined based on the ideal length IL of the upstream additional stitch Su, the multiplied value may be shorter than the ideal length IL. In this case, the downstream additional stitch Sd and the two stitches Sp downstream of the bend are formed closer to the inside, resulting in the bending angle of the inner stitch being smaller than the bending angle A and resulting in a pointed shape, a phenomenon known as a "beak," which causes a problem of a deterioration in the appearance of the stitching quality.

[0064] Furthermore, as shown in FIG. 12, depending on the values ​​of the downstream stitch count ON and the downstream correction stitch pitch OP, which are determined based on the ideal length OL of the downstream additional stitch Sd, the corrected length OLC of the downstream additional stitch Sd, which is the product of these values, may be shorter than the ideal length OL. In this case, the stitching pitch P of the first stitch of the two stitches Sp downstream of the bend, which start from the end of the downstream additional stitch Sd, becomes a short stitching pitch Pf only for the inner stitch, causing a phenomenon known as "stitch clogging," which results in a deterioration in the appearance of the stitching quality.

[0065] To solve these problems, the CPU 91 of the control device 90 may execute an acquisition process (2) instead of the acquisition process (1) that realizes a method for acquiring each derived parameter based on each set parameter. This acquisition process (2) is realized by cooperation of the upstream additional stitch acquisition unit 911, the upstream correction length acquisition unit 912, the downstream additional stitch acquisition unit 913, the downstream correction length acquisition unit 914, and the diagonal side acquisition unit 915 of the CPU 91.

[0066] 13 to 16 are explanatory diagrams showing the order of parameter acquisition steps in the parameter acquisition process (2). Arrow C in Fig. 13 to 16 indicates the direction in which a stitch, which is the course of sewing, is formed.

[0067] 13 to 16, in corner stitching for one bend, two stitches Sp, an upstream additional stitch Su, a downstream additional stitch Sd, and two more stitches Sp are formed in this order. The needle points for the two stitches Sp are shown as black dots, the needle points for the upstream additional stitch Su are shown as hatched dots, and the needle points for the downstream additional stitch Sd are shown as white dots.

[0068] In order to perform the corner stitching, the upstream additional stitch obtaining unit 911 derives the ideal length IL of the upstream additional stitch Su (upstream additional stitch obtaining step). The method of this derivation is the same as that of the acquisition process (1), and the ideal length IL of the upstream additional stitch Su is acquired from the following equation. IL=W / tan(A / 2)

[0069] Next, the upstream correction length acquisition unit 912 determines the upstream correction stitch pitch IP and the upstream stitch count IN from the ideal length IL of the upstream additional stitch Su (upstream correction length acquisition step). The upstream correction length acquisition unit 912 multiplies the upstream correction stitch pitch IP by the upstream stitch count IN to calculate the correction length ILC of the upstream additional stitch Su, and determines the upstream correction stitch pitch IP and the upstream stitch count IN so that the correction length ILC approximates the ideal length IL of the upstream additional stitch Su and is greater than or equal to the ideal length IL.

[0070] More specifically, the upstream-side correction length acquisition unit 912 prepares a plurality of candidate values ​​for each of the upstream-side correction stitch pitch IP and the upstream-side stitch count IN. If the candidate value of the upstream-side correction stitch pitch IP deviates significantly from the set stitch pitch P, the sewing quality may be deteriorated. Therefore, all candidate values ​​should be set to values ​​within a specified range with the set stitch pitch P as the center. For example, a range of predetermined ratio values ​​is set above and below the set stitch pitch P as the center. Here, all numerical values ​​within a range of ±20% of the set stitch pitch P and at intervals of the set resolution of the stitch pitch P (for example, 0.1 mm) are set as candidate values ​​for the upstream-side correction stitch pitch IP. The ratio value that determines the candidate value for the upstream correction stitch pitch IP is not limited to ±20%, and it is preferable that the upper and lower limits can be arbitrarily set by input means such as the operation input device 95, for example.

[0071] The candidate value for the upstream stitch count IN is an integer value close to the division value of the set stitch pitch P relative to the ideal length IL of the upstream additional stitch Su, more specifically, an integer value before or after the division value, in order to prevent the upstream correction stitch pitch IP from deviating significantly from the set stitch pitch P.

[0072] FIG. 17 is a table showing a list of all the candidate values ​​of the upstream correction stitch pitch IP and the number of upstream stitches IN based on specific numerical examples. The set stitch pitch P is set to 3.0 [mm], the default ratio value is set to ±20%, and the candidate value of the upstream correction stitch pitch IP is set to a value between 2.4 and 3.6 [mm] in increments of 0.1 [mm]. The ideal length IL of the upstream additional stitch Su is set to 3.7 [mm], and the candidate value for the number of upstream stitches IN is set to 1 or 2. Among all the candidate values ​​of the corrected length ILC of the upstream additional stitch Su resulting from all the combinations of all the candidate values ​​of the upstream correction stitch pitch IP and all the candidate values ​​of the upstream number of stitches IN, the case that is equal to or greater than the ideal length IL of the upstream additional stitch Su and closest to the ideal length IL is when the candidate value of the upstream correction stitch pitch IP, shown by hatching in the diagram, is 2.4 [mm], the candidate value of the upstream number of stitches IN is 2, and the candidate value of the corrected length ILC of the upstream additional stitch Su is 4.8 [mm]. Therefore, in the example of FIG. 17, the upstream correction stitch pitch IP is determined to be 2.4 [mm], the number of upstream stitches IN is determined to be 2, and the correction length ILC of the upstream additional stitch Su is determined to be 4.8 [mm].

[0073] Next, as shown in Figure 14, the diagonal side acquisition unit 915 acquires the length N of the diagonal side consisting of the line segment connecting the corrected vertex Vor of the bend of the outer stitch and the vertex Vi of the bend of the inner stitch based on the corrected length ILC of the upstream additional stitch Su determined by the upstream corrected length acquisition unit 912 (diagonal side acquisition process). As shown in FIG. 14, the length N of the oblique side corresponds to the length of the hypotenuse of a right triangle whose two sides other than the oblique side are the stitch width W and the corrected length ILC of the upstream additional stitch Su, respectively. Therefore, the length N of the diagonal side can be obtained from the following formula: N=(W 2 +ILC 2 ) 1 / 2

[0074] Next, as shown in Figure 15, the downstream additional stitch acquisition unit 913 acquires the ideal length OL of the downstream additional stitch Sd based on the interior angle α between the upstream additional stitch Su and the diagonal side and the length N of the diagonal side (downstream additional stitch acquisition process). As shown in Figure 15, if the interior angle between the diagonal side and the downstream additional stitch Sd is β, the length of the side adjacent to the vertex where the angle of the right triangle is β is the ideal length OL of the downstream additional stitch Sd. The length of the hypotenuse of this right triangle is the length of the oblique side N, and the length of the side opposite the vertex where the angle is β is the stitch width W. The angle β is set so that the sum of the angle β and the angle α coincides with the flexion angle A. Therefore, the ideal length OL of the downstream additional stitch Sd can be obtained from the following equation. OL=N×cosβ=N×cos(A-α) Also, the angle α can be obtained from the following equation according to FIG. tan α=W / ILC α=tan -1 (W / ILC)

[0075] Next, the downstream side correction length acquisition unit 914 determines the downstream side correction stitch pitch OP and the downstream side stitch count ON from the ideal length OL of the downstream side additional stitch Sd (downstream side correction length acquisition step). Here, the downstream correction length acquisition unit 914 selects the first acquisition method if the ideal length OL of the downstream additional stitch Sd obtained by the downstream additional stitch acquisition unit 913 is equal to or greater than the set stitch pitch P, and selects the second acquisition method if it is less than the set stitch pitch P.

[0076] When the first acquisition method is selected, the downstream correction length acquisition unit 914 determines the downstream correction stitch pitch OP and the downstream stitch number ON so that the corrected length OLC of the downstream additional stitch Sd, obtained by multiplying the downstream correction stitch pitch OP and the downstream stitch number ON, approximates the ideal length OL of the downstream additional stitch Sd and is greater than or equal to the ideal length OL.

[0077] More specifically, the downstream side correction length acquisition unit 914 prepares a plurality of candidate values ​​for each of the downstream side correction stitch pitch OP and the downstream side stitch count ON. If the candidate value of the downstream side correction stitch pitch OP deviates significantly from the set stitch pitch P, the sewing quality may be deteriorated. Therefore, all candidate values ​​should be set to values ​​within a specified range with the set stitch pitch P as the center. In this case, too, all numerical values ​​at intervals of the set resolution (for example, 0.1 mm) of the stitch pitch P within a range of a predetermined ratio value, for example, ±20%, above and below the set stitch pitch P as the center are set to the candidate values ​​of the downstream side correction stitch pitch OP. This ratio value is not limited to ±20%, and it is preferable that the upper and lower limits can be set arbitrarily by input means such as the operation input device 95.

[0078] The candidate value for the downstream stitch count ON is an integer value close to the division value of the set stitch pitch P relative to the ideal length OL of the downstream additional stitch Sd, more specifically, an integer value before or after the division value, in order to prevent the downstream correction stitch pitch OP from deviating significantly from the set stitch pitch P.

[0079] FIG. 18 is a table showing a list of all the candidate values ​​for the downstream side correction stitch pitch OP and all the candidate values ​​for the downstream side stitch count ON, based on specific numerical examples. The set stitch pitch P is set to 3.0 [mm], the default ratio value is set to ±20%, and the candidate value for the downstream side correction stitch pitch OP is set to a value between 2.4 and 3.6 [mm] in increments of 0.1 [mm]. The ideal length OL of the downstream additional stitch Sd is set to 3.1 [mm], and the candidate value for the number of downstream stitches ON is set to 1 or 2. Among all the candidate values ​​of the corrected length OLC of the downstream side additional stitch Sd resulting from all the combinations of all the candidate values ​​of the downstream side correction stitch pitch OP and all the candidate values ​​of the number of downstream side stitches ON, the value that is equal to or greater than the ideal length OL of the downstream side additional stitch Sd and that is closest to the ideal length OL is the case where the candidate value of the upstream side correction stitch pitch OP, shown by hatching in the diagram, is 3.1 [mm], the candidate value of the downstream side number of stitches ON is 1, and the candidate value of the corrected length OLC of the downstream side additional stitch Sd is 3.1 [mm]. Therefore, in the example of FIG. 18, the downstream side correction stitch pitch OP is determined to be 3.1 [mm], the downstream side stitch number ON is determined to be 1, and the correction length OLC of the downstream side additional stitch Sd is determined to be 3.1 [mm].

[0080] The downstream correction length acquisition unit 914 that has selected the first acquisition method determines an upper threshold value for the difference between the correction length OLC and the ideal length OL so that the correction length OLC of the downstream additional stitch Sd does not deviate too much from the ideal length OL. For example, as described above, if the ratio value set for the set stitch pitch P is 20%, the ratio value obtained by multiplying this by 70% is set as the upper threshold value. In this case, if the value obtained by subtracting the ideal length OL from the correction length OLC exceeds the value of ideal length OL × 20% × 70%, the downstream correction length acquisition unit 914 changes the candidate value that was the basis for the correction length OLC to the next smaller candidate value.

[0081] For example, in the example of Figure 18, if the candidate value for the correction length OLC of the downstream additional stitch Sd differs from the ideal length OL of the downstream additional stitch Sd by a difference greater than the ideal length OL x 20% x 70%, the candidate value for the correction length OLC is changed to a value one level lower. 18, the candidate value for the correction length OLC matches the ideal length OL, so the candidate value does not change. If the candidate value for the correction length OLC were 3.6 [mm], there would be a difference (0.5 [mm]) greater than the ideal length OL (3.1 [mm]), which is 0.43 [mm], which is the ideal length OL × 20% × 70%, so the candidate value for the correction length OLC, which is one value smaller, 3.5 [mm], would be adopted.

[0082] It is preferable that the ratio value that is the threshold value of this correction length OLC can be arbitrarily set by input means such as the operation input device 95. In the above description, an example of a threshold value that is further multiplied by the threshold value for the set stitch pitch P has been described, but it is also possible to set a threshold value that is further multiplied by the threshold value for the set stitch pitch P, or to set a threshold value that is multiplied by the ideal length OL regardless of the threshold value for the set stitch pitch P.

[0083] Also, when the second acquisition method is selected, the downstream correction length acquisition unit 914 determines the downstream stitch count ON to be 1 because the ideal length OL of the downstream additional stitch Sd is less than the set stitch pitch P, and sets the downstream correction stitch pitch OP to be equal to the ideal length OL of the downstream additional stitch Sd.

[0084] However, if the ideal length OL of the downstream side additional stitch Sd is less than a predetermined ratio (for example, 50%) of the set stitch pitch P, the downstream side correction length acquisition unit 914 sets the downstream side stitch count ON to 0. In other words, since the needle entry for forming the downstream side additional stitch Sd is not performed, the value of the downstream side correction stitch pitch OP is not determined. This is because if the downstream stitch count ON is not set to 0, the needle drop position of the final stitch of the upstream additional stitch Su and the needle drop position forming the downstream additional stitch Sd will be too close compared to the set stitch pitch P, causing the stitches to become crowded, resulting in a decrease in stitch quality. It is preferable that the predetermined ratio to the set stitch pitch P can also be arbitrarily set by input means such as the operation input device 95.

[0085] These allow the CPU 91 to obtain the derived parameters. The CPU 91 obtains derived parameters for each bent portion based on the setting parameters set for each bent portion, generates sewing data for a series of stitches, and registers the data in the data memory 94. In addition, in the case of sewing data generated based on the process (2) for obtaining derived parameters for corner stitching, corner stitching can also be performed by corner stitching control based on the flowchart of Figure 10, which is executed by the corner stitching control unit 916 described above.

[0086] [Effects of the embodiment] The twin-needle sewing machine 100 functions as an acquisition device in which the CPU 91 of the control device 90 has an upstream additional stitch acquisition unit 911 that determines the ideal length IL of the upstream additional stitch Su based on the bending angle A and the stitch width W of the two stitches Sp, an upstream corrected length acquisition unit 912 that determines the upstream corrected stitch pitch IP and the upstream stitch number IN obtained by correcting the set stitch pitch P, a downstream additional stitch acquisition unit 913 that determines the ideal length OL of the downstream additional stitch Sd, and a downstream corrected length acquisition unit 914 that determines the downstream corrected stitch pitch OP and the downstream stitch number ON obtained by correcting the set stitch pitch P. Therefore, if the bending angle A, stitch width W and set stitch pitch P are known, it is possible to easily obtain the upstream number of stitches IN of the upstream additional stitch Su required for corner stitching, the upstream correction stitch pitch IP of the upstream additional stitch Su, the ideal length IL of the upstream additional stitch Su, the downstream number of stitches ON of the downstream additional stitch Sd, the downstream correction stitch pitch OP of the downstream additional stitch Sd and the ideal length OL of the downstream additional stitch Sd, and it is possible to reduce the workload of adjusting these values ​​to find the desired stitches.

[0087] In addition, when the CPU 91 executes the process (1) for acquiring the derivation parameters for corner stitching, the upstream correction length acquisition unit 912 acquires the upstream stitch count IN based on the value obtained by dividing the ideal length IL of the upstream additional stitch Su by the set stitch pitch P, and acquires the upstream correction stitch pitch IP based on the value obtained by dividing the ideal length IL of the upstream additional stitch Su by the upstream stitch count IN, and the downstream correction length acquisition unit 914 acquires the downstream stitch count ON based on the value obtained by dividing the ideal length OL of the downstream additional stitch Sd by the set stitch pitch P, and acquires the downstream correction stitch pitch OP based on the value obtained by dividing the ideal length OL of the downstream additional stitch Sd by the downstream stitch count ON. Therefore, it is possible to easily obtain more appropriate values ​​for the upstream stitch count IN, the upstream correction stitch pitch IP of the upstream additional stitch Su, the downstream stitch count ON, and the downstream correction stitch pitch OP of the downstream additional stitch Sd.

[0088] Furthermore, when the CPU 91 executes the process (2) for acquiring the derived parameters for corner stitching, the upstream correction length acquisition unit 912 determines the upstream correction stitch pitch IP and the number of upstream stitches IN so that the correction length ILC of the upstream additional stitch Su is equal to or greater than the ideal length IL, and the downstream correction length acquisition unit 914 determines the downstream correction stitch pitch OP and the number of downstream stitches ON so that the correction length OLC of the downstream additional stitch Sd is equal to or greater than the ideal length OL. By setting the corrected length ILC of the upstream additional stitch Su to be equal to or greater than the ideal length IL, it is possible to suppress the "beak" phenomenon shown in Figure 11, in which the angle of the inner stitch's interior angle is reduced, and improve the seam quality. Furthermore, by setting the corrected length OLC of the downstream additional stitch Sd to be equal to or greater than the ideal length OL, it is possible to suppress the phenomenon of "stitch clogging" shown in Figure 12, in which the pitch of the first stitch decreases after passing the apex of the bend in the inner stitch, thereby improving the seam quality.

[0089] In addition, when executing the process (2) for acquiring the derived parameters for corner stitching, the CPU 91 has a diagonal side acquisition unit 915 that acquires the length N of the diagonal side consisting of the line segment connecting the corrected vertex Vor of the bend of the outer stitch based on the corrected length ILC of the upstream additional stitch and the vertex Vi of the bend of the inner stitch, so that the downstream corrected stitch pitch OP and the downstream stitch count ON are determined taking into account the fluctuation of the corrected length ILC with respect to the ideal length IL of the upstream additional stitch Su. Therefore, the downstream side correction stitch pitch OP and the downstream side stitch number ON can be further optimized, and the stitch quality can be improved.

[0090] Furthermore, when the CPU 91 executes the process (2) for acquiring the derived parameters for corner stitching, the upstream correction length acquisition unit 912 determines, as the upstream correction stitch pitch IP and the upstream stitch number IN, the candidate value for the upstream correction stitch pitch IP and the candidate value for the upstream stitch number IN that is closest to the ideal length IL of the upstream additional stitch Su and is equal to or greater than the ideal length IL of the upstream additional stitch Su, from among a plurality of candidate values ​​for the correction length ILC of the upstream additional stitch Su, which are obtained by combining and multiplying a plurality of candidate values ​​for the upstream correction stitch pitch IP and one or a plurality of candidate values ​​for the upstream stitch number IN. Therefore, the upstream side correction stitch pitch IP and the upstream side stitch number IN can be further optimized, and the stitching quality can be improved.

[0091] Furthermore, when the CPU 91 executes the process (2) for acquiring the derived parameters for corner stitching, the downstream correction length acquisition unit 914 determines, as the downstream correction stitch pitch OP and the downstream stitch number ON, the candidate value of the downstream correction stitch pitch OP and the candidate value of the downstream stitch number ON that is closest to the ideal length OL of the downstream additional stitch Sd and is equal to or greater than the ideal length OL of the downstream additional stitch Sd, from among a plurality of candidate values ​​for the correction length OLC of the downstream additional stitch Sd obtained by combining and multiplying a plurality of candidate values ​​for the downstream correction stitch pitch OP and one or a plurality of candidate values ​​for the downstream stitch number ON. Therefore, the downstream side correction stitch pitch OP and the downstream side stitch number ON can be further optimized, and the stitch quality can be improved.

[0092] In addition, when the CPU 91 executes the process (2) for acquiring the derived parameters for corner stitching, it sets all candidate values ​​for the upstream correction stitching pitch IP and all candidate values ​​for the downstream correction stitching pitch OP to values ​​within a specified range including the set stitching pitch P. This prevents the upstream correction stitch pitch IP and the downstream correction stitch pitch OP from being set to values ​​that deviate from the set stitch pitch P, thereby enabling sewing with a more uniform stitch pitch and improving the stitching quality.

[0093] In addition, when the CPU 91 executes the process (2) for acquiring the derived parameters for corner stitching, the downstream correction length acquisition unit 914 corrects the correction length OLC to a candidate value that is one level smaller if the difference between the correction length OLC of the downstream additional stitch Sd and the ideal length OL of the downstream additional stitch Sd exceeds a predetermined upper threshold. The symbol Z in Figure 16 indicates the pitch of the first stitch after passing the apex of the bent part of the inner stitch along the stitch forming direction. The pitch Z can be expressed by the following formula. Z=OLC-OL+P Therefore, by setting a predetermined upper threshold value for the difference between the corrected length OLC of the downstream additional stitch Sd and the ideal length OL of the downstream additional stitch Sd, it is possible to prevent the pitch Z from becoming too long and improve the sewing quality by making the stitching pitch uniform. Furthermore, in the aforementioned Figure 18, the values ​​of the pitch Z are listed for all candidate values ​​of the correction length OLC of the downstream additional stitch Sd, and it can be seen that the value of the pitch Z (3.0 [mm]) of the candidate value (3.1 [mm]) determined for the correction length OLC is equal to the set stitch pitch P (3.0 [mm]).

[0094] In addition, when the CPU 91 executes the process (2) for acquiring the derived parameters for corner stitching, if the ideal length OL of the downstream additional stitch Sd obtained by the downstream additional stitch acquisition unit 913 is smaller than the set stitch pitch P, the downstream correction length acquisition unit 914 sets the downstream stitch count ON to 1 and sets the downstream correction stitch pitch OP and the ideal length OL of the downstream additional stitch to the same value. This eliminates the need to search for an appropriate combination of multiple candidate values ​​for the downstream correction stitch pitch OP and multiple candidate values ​​for the downstream stitch count ON, thereby reducing the workload and shortening the work time.

[0095] In addition, when the CPU 91 executes the process (2) for acquiring the derived parameters for corner stitching, the downstream correction length acquisition unit 914 sets the downstream stitch count ON to 0 if the ideal length OL of the downstream additional stitch obtained by the downstream additional stitch acquisition unit 913 is equal to or less than the specified multiplier of the set stitch pitch P. This makes it possible to prevent the formation of stitches with a narrow stitch pitch width that deviates from the set stitch pitch P as the downstream side additional stitch Sd, thereby improving the stitching quality.

[0096] [others] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. For example, in the embodiments, a component integrally formed from a single member may be replaced with a component divided into multiple members that are connected or fixed to each other. Furthermore, a component formed by connecting multiple members may be replaced with a component integrally formed from a single member. In addition, the details shown in the embodiments may be modified as appropriate without departing from the spirit of the invention.

[0097] For example, the switching mechanism 80 may be configured to include an actuator that detects the input position of the switching lever 83 with a sensor, and the control device 90 positions the switching member 81 at the input position of the switching lever 83 based on the detection.

[0098] In addition, in the above embodiment, a configuration was exemplified in which the twin-needle sewing machine 100 performs the process (1) for acquiring derived parameters for corner stitching and the process (2) for acquiring derived parameters for corner stitching, but the sewing machine or acquisition device may perform only one of them. In the case of an acquisition device or a twin-needle sewing machine that only performs the process (1) of acquiring derived parameters for corner stitching, the CPU 91 may be configured not to include the diagonal side acquisition unit 915.

[0099] In addition, in the above embodiment, the CPU 91 of the control device 90 of the twin-needle sewing machine 100 is exemplified as the acquisition device, but the acquisition device is not limited to this and may be configured as an information processing terminal such as a personal computer, tablet, or smartphone. The acquisition method performed by the CPU 91 as an acquisition device may be performed by any information processing terminal or by a device other than an information processing terminal. In this case, it is preferable that the information processing terminal or other device be able to transfer data of all corner stitching parameters obtained as an acquisition device to the control device of the twin needle sewing machine 100 by data communication or by transferring a recording medium. The acquisition method performed by the CPU 91 as an acquisition device may be implemented as part of a control method for the sewing machine. [Explanation of symbols]

[0100] 3 Operation pedal 7 sewing needles 10 Needle bar mechanism 11 Sewing machine motor 12 Feed adjustment motor 20 Needle bar 50 Needle vertical movement mechanism 51 Stick hug 60 Clutch mechanism 70 Stopper mechanism 80 Switching Mechanism 81 Switching member 82 Solenoid 83 Switching lever 84 Switching lever sensor 90 Control device 91 CPU 94 Data Memory 95 Operation input device 96 Touch Sensor 97 Display Panel 100 twin needle sewing machine 911 Additional upstream stitch acquisition section 912 Upstream correction length acquisition unit 913 Downstream additional stitch acquisition section 914 Downstream correction length acquisition unit 915 Oblique side acquisition part 916 Corner stitching control unit A flexion angle C Seam formation direction IL Ideal length ILC Correction Length IN Number of upstream stitches IP Pitch ON Number of stitches on downstream side OP Pitch OL ideal length OLC Correction Length P Setting stitch pitch Sd Additional downstream stitch Sp Two stitches Su Additional upstream stitch Vi Vertex Vor Correction Vertex W stitch width Z pitch α angle β angle

Claims

1. An acquisition device for acquiring corner stitching parameters for a twin-needle sewing machine that is equipped with a needle bar mechanism that holds two sewing needles and is capable of selectively performing twin-needle sewing, which forms two parallel stitches, and single-needle sewing, which uses a single sewing needle, and a feed mechanism that feeds a workpiece on a needle plate at an arbitrary set stitch pitch in synchronization with the needle bar mechanism, and that forms the two parallel stitches with a constant stitch width and by bending each of the two stitches at the same bending angle based on the set stitch pitch, an upstream additional stitch acquisition unit that calculates an ideal length of an upstream additional stitch that is formed upstream of the apex of the bend of the outer stitch and in excess of the inner stitch based on the bend angle and the stitch width of the two stitches; an upstream-side corrected length acquisition unit that determines an upstream-side corrected stitch pitch and the number of upstream stitches by correcting the set stitch pitch based on the ideal length of the upstream-side additional stitch; a downstream additional stitch obtaining unit that obtains an ideal length of a downstream additional stitch that is formed downstream of the apex of the bend of the outer stitch and in excess of the inner stitch; a downstream side corrected length acquisition unit that determines a downstream side corrected stitch pitch and the number of downstream side stitches by correcting the set stitch pitch based on the ideal length of the downstream side additional stitch; An acquisition device comprising:

2. the upstream-side correction length acquisition unit acquires the number of upstream-side stitches based on a value obtained by dividing the ideal length of the upstream-side additional stitch by the set stitch pitch, and acquires the upstream-side correction stitch pitch based on a value obtained by dividing the ideal length of the upstream-side additional stitch by the upstream-side number of stitches, The acquisition device according to claim 1, characterized in that the downstream correction length acquisition unit acquires the number of downstream stitches based on a value obtained by dividing the ideal length of the downstream additional stitch by the set stitch pitch, and acquires the downstream correction stitch pitch based on a value obtained by dividing the ideal length of the downstream additional stitch by the number of downstream stitches.

3. a diagonal side acquisition unit that acquires the length of a diagonal side formed by a line segment connecting a corrected vertex of a bent portion of the outer stitch and a vertex of a bent portion of the inner stitch based on the corrected length of the upstream additional stitch, which is the multiplication value of the upstream corrected stitch pitch obtained by the upstream corrected length acquisition unit and the number of upstream stitches, the upstream-side correction length acquisition unit determines the upstream-side correction stitch pitch and the upstream-side number of stitches so that the correction length of the upstream-side additional stitch is equal to or greater than the ideal length of the upstream-side additional stitch, the downstream side additional stitch acquisition unit calculates an ideal length of the downstream side additional stitch based on an interior angle between the upstream side additional stitch and the oblique side and a length of the oblique side; The acquisition device according to claim 1, characterized in that the downstream correction length acquisition unit determines the downstream correction stitch pitch and the number of downstream stitches so that the corrected length of the downstream additional stitch, which is the multiplied value of the downstream correction stitch pitch and the number of downstream stitches, is equal to or greater than the ideal length of the downstream additional stitch.

4. 4. The acquisition device according to claim 3, wherein the upstream correction length acquisition unit determines, as the upstream correction stitch pitch and the upstream stitch count, the candidate value of the upstream correction stitch pitch and the candidate value of the upstream stitch count that are closest to the ideal length of the upstream additional stitch and are equal to or greater than the ideal length of the upstream additional stitch, from among a plurality of candidate values ​​of the correction length of the upstream additional stitch obtained by combining and multiplying a plurality of candidate values ​​of the upstream correction stitch pitch and one or a plurality of candidate values ​​of the upstream stitch count.

5. 5. The acquisition device according to claim 4, wherein the downstream-side correction length acquisition unit determines, as the downstream-side correction stitch pitch and the downstream-side number of stitches, the candidate value of the downstream-side correction stitch pitch and the candidate value of the downstream-side number of stitches that are closest to the ideal length of the downstream-side additional stitch and are equal to or greater than the ideal length of the downstream-side additional stitch, among a plurality of candidate values ​​of the correction length of the downstream-side additional stitch obtained by combining and multiplying a plurality of candidate values ​​of the downstream-side correction stitch pitch and one or a plurality of candidate values ​​of the downstream-side stitch number.

6. The acquisition device according to claim 5, wherein all candidate values ​​of the upstream side correction stitching pitch and all candidate values ​​of the downstream side correction stitching pitch are set to values ​​within a specified range including the set stitching pitch.

7. The acquisition device described in claim 6, characterized in that the downstream correction length acquisition unit changes the correction length of the downstream additional stitch to the candidate value one level smaller when the difference between the correction length of the downstream additional stitch and the ideal length of the downstream additional stitch exceeds a predetermined upper threshold.

8. The downstream correction length acquisition unit When the ideal length of the downstream side additional stitch obtained by the downstream side additional stitch obtaining unit is smaller than the set stitch pitch, 4. The acquisition device according to claim 3, wherein the number of stitches on the downstream side is set to 1, and the downstream side correction stitch pitch and the ideal length of the downstream side additional stitch are set to the same value.

9. The downstream correction length acquisition unit When the ideal length of the downstream side additional stitch obtained by the downstream side additional stitch obtaining unit is equal to or less than a specified ratio of the set stitch pitch, The acquisition device according to claim 8 , wherein the downstream stitch number is set to 0.

10. A twin-needle sewing machine is provided with a needle bar mechanism that holds two sewing needles and is capable of selectively performing twin-needle sewing, which forms two parallel stitches, and single-needle sewing with one sewing needle, and a feed mechanism that feeds an object to be sewn on a needle plate at an arbitrary set stitch pitch in synchronization with the needle bar mechanism, and forms the two parallel stitches with a constant stitch width by bending each of the two stitches at the same bending angle based on the set stitch pitch, An acquisition device according to any one of claims 1 to 9; a corner stitching control unit that controls the needle bar mechanism and the feed mechanism based on corner stitching parameters acquired by the acquisition device.

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