WO2019043813A1

WO2019043813A1 - Sewing machine

Info

Publication number: WO2019043813A1
Application number: PCT/JP2017/031065
Authority: WO
Inventors: 孝志甲斐; 東一上野; 俊介吉田; 士朗若山; 信明濱田; 良太坂神; 悠輔生嶋; 晋谷川
Original assignee: 三菱電機株式会社
Priority date: 2017-08-30
Filing date: 2017-08-30
Publication date: 2019-03-07
Also published as: CN111065773B; JP6477987B1; CN111065773A; DE112017008004T5; JPWO2019043813A1; DE112017008004B4

Abstract

A sewing machine (100) is provided with: a shuttle (132) which captures a needle thread inserted in a needle hole of a sewing needle (131) so as to entangle the needle thread with a bobbin thread; a thread take-up lever (133) having a small hole in which the needle thread is inserted; a conveyance means (P1) which conveys an object to be sewn; a center presser (135) which prevents raising of the object to be sewn; a drive source (136) which drives the center presser (135); and a tension monitoring unit which monitors the tension of the needle thread on the basis of a load that is applied from the needle thread to the center presser (135) when the needle thread comes into contact with the center presser (135) during conveyance of the object to be sewn by the conveyance means (P1).

Description

sewing machine

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a sewing machine provided with an inner presser that presses a workpiece at the time of sewing.

Conventionally, an upper thread of a sewing machine is supplied along a thread path starting from a supply source such as thread winding installed on an arm portion or a stand and ending at a sewing needle serving as a consuming portion of the upper thread.

Patent Document 1 discloses an upper thread tension detector that detects the tension of an upper thread during sewing operation by providing a piezoelectric element in the above-described thread path. Moreover, in patent document 1, the piezoelectric element is arrange | positioned in the position which can contact upper thread, and it describes about the sewing machine which detects thread breakage by upper thread contacting with this piezoelectric element. In Patent Document 2, a strain gauge is provided in the above-described yarn path, the tension waveform of the upper thread with respect to the rotational phase of the sewing machine main axis is calculated based on the output, and the tension of the upper thread is adjusted according to the shape of the tension waveform. Automatic thread tension sewing machines have been released.

Patent Documents 3 and 4 show sewing machines that not only detect the tension of the upper thread but also control the tension of the upper thread in accordance with the sewing pattern using an upper thread tension adjusting device and an upper thread tensioning means. Specifically, Patent Document 3 shows an upper thread tension adjusting device that makes the resistance of the upper thread nipped between the fixing plate and the thread pressure end plate variable at the time of sewing operation by pressing force or torque applied by an electromagnetic actuator or the like. It is done. Patent Document 4 discloses a sewing machine having a thread tensioning means for optimally adjusting the tension of the thread, even when the width and direction of the seam constantly change, for the purpose of creating an embroidery product having a good texture. It is done. Further, Patent Documents 3 and 4 describe a configuration of feedback control that adjusts the thread tension based on the output of an upper thread tension detector (a tension detection means in Patent Document 4) that detects thread tension by a piezoelectric element or a detection coil. It is done.

And in patent document 5, it equips with the separate motor for driving each mechanical elements, such as a needle bar, a balance, and a cloth presser, respectively, The torque data predetermined according to the rotation angle of the motor which drives a balance A sewing machine is disclosed that controls the tension of the upper thread based on the current value supplied to the motor and the motor.

By the way, in the vicinity of the end point of the above-described yarn path, a pressing device for a material to be sewn, which is generally called cloth pressing or middle pressing, is attached in order to prevent floating of the material to be sewn. Patent Document 6 discloses a sewing machine that improves the pressing accuracy of a workpiece by controlling the driving force of a motor that drives the pressing device. Patent Document 7 discloses a sewing machine that detects the thickness and hardness of a material to be sewn based on the rotational angle of a motor that drives a middle press and the detection value of a driving torque.

As described above, Patent Documents 1 to 5 disclose a sewing machine provided with a device for detecting or controlling upper thread tension during sewing operation for the purpose of improving sewing quality such as thread breakage or thread tension due to upper thread tension. There is. Further, Patent Documents 6 and 7 disclose sewing machines that change the operation pattern of the pressing device for the purpose of improving sewing quality such as tightening accuracy due to pressing accuracy of the sewing object by the pressing device.

Unexamined-Japanese-Patent No. 6-343784 gazette JP-A-7-662 JP-A-11-47479 JP-A-7-661 JP, 2010-178785, A Unexamined-Japanese-Patent No. 11-19358 gazette JP, 2010-131175, A

However, in the case of detecting the tension of the upper thread with the sewing machine disclosed in Patent Documents 1 to 4, in any case, a yarn tension detection device configured with a piezoelectric element, a strain gauge, etc. The need for installation increases the manufacturing cost of the sewing machine. In addition, the maintenance cost of the sewing machine increases because it is necessary to calibrate changes in the sensitivity and the bandwidth of the detector due to aging. Further, when a detector is provided in the yarn path, there is a restriction on the structural design such as an increase in the length of the yarn path and securing of an installation space, and there is a problem that the layout of the sewing machine head is limited. Moreover, the sewing machine of patent document 5 needs to be equipped with the motor which drives a balance separately. In short, the conventional sewing machines disclosed in Patent Documents 1 to 5 have many parts to be added to the sewing mechanism when detecting the upper thread tension, and the increase in cost and design constraints becomes a problem.

On the other hand, the sewing machines disclosed in Patent Documents 6 and 7 can improve the sewing quality such as the above-mentioned tightening accuracy because the pressing accuracy of the sewing material is improved by changing the operation pattern of the pressing device. . However, since the behavior of the upper thread, that is, the supply amount of upper thread, tension, and the like is not monitored, for example, if thread breakage occurs, a stitch is not formed and a sewing failure occurs. In addition, the sewing operation is continued even if the thread tension or texture is disturbed due to an external factor. In the sewing machines of Patent Documents 6 and 7, when checking sewing quality such as thread tension and texture, it is necessary to check the finishing condition after a series of sewing operations are completed by using an inspection device or the like. In short, the conventional sewing machines disclosed in Patent Documents 6 and 7 drive the pressing device so that the sewing quality such as thread tension and tightening accuracy is improved, but guaranteeing the quality of the formed seam There was a problem that I could not

The present invention has been made in view of the above, and monitors occurrence of thread breakage while performing sewing operation with a simple configuration with few additional parts, and further guarantees sewing quality such as thread tension and tightening accuracy. Aims to provide a sewing machine that can

The sewing machine according to the present invention has a sewing needle having a needle hole for inserting the upper thread, a hook for catching the upper thread, and a small hole for inserting the upper thread. A balance that pulls up the upper thread from the sewing object to be sewn by raising the small hole from the bottom dead center to the top dead center, a middle presser that prevents the sewn product from floating, and a drive source that drives the middle presser The upper thread tension is monitored based on the load applied from the upper thread to the middle presser by the transport means for transporting the sewn material and the upper thread contacting the middle presser when the transport means transports the sewn material And a tension monitoring unit.

According to the present invention, it is possible to detect the tension applied to the upper thread through the middle press, to perform the sewing operation and to detect thread breakage and tightening accuracy related to sewing quality with a simple configuration with few additional parts. be able to.

The perspective view which shows the whole structure of the sewing machine which concerns on Embodiment 1 The perspective view which shows the detail of the conveyance mechanism of the sewing machine concerning Embodiment 1 A perspective view showing a sewing mechanism of a sewing machine according to a first embodiment FIG. 17 is a perspective view showing details of an inner pressing drive mechanism of the sewing machine according to the first embodiment. A perspective view showing an upper thread path of a sewing machine according to a first embodiment Block diagram showing the control configuration of the sewing machine according to the first embodiment Image showing the operation of a typical electronic sewing machine Image showing tension detection operation of the sewing machine according to the first embodiment A timing chart showing operation patterns of a sewing needle according to the general electronic sewing machine and the sewing machine according to the first embodiment Timing chart showing the operation of the sewing machine according to the first embodiment Block diagram showing details of PF axis motor control calculation unit of sewing machine according to the first embodiment Block diagram showing details of the PF axis deviation suppression unit of the sewing machine according to the first embodiment Block diagram showing the details of the tension monitoring unit of the sewing machine according to the first embodiment Timing chart showing the operation of the sewing machine according to the second embodiment Image showing the problem of tension detection operation of the sewing machine according to the third embodiment Timing chart showing the operation of the sewing machine according to the third embodiment Block diagram showing details of PF axis motor control calculation unit of sewing machine according to Embodiment 4 Block diagram showing details of the PF axis deviation suppression unit of the sewing machine according to the fourth embodiment A diagram showing a first hardware configuration example of a control board of a sewing machine according to Embodiments 1 to 4. A diagram showing a second hardware configuration example of a control board of a sewing machine according to Embodiments 1 to 4.

Hereinafter, a sewing machine according to an embodiment of the present invention will be described in detail based on the drawings. The present invention is not limited by the embodiment.

Embodiment 1
In the first embodiment, a configuration example of an industrial electronic sewing machine that performs a sewing operation while moving a workpiece to be sewed such as cloth or leather with a transport device such as an XY table will be described. However, as long as it is a sewing machine provided with pressing devices such as cloth pressing and middle pressing and capable of conveying the material to be sewn so that the upper thread comes in contact with the pressing devices, for example, general sewing machines, vocational sewing machines, home The configuration example of the present embodiment can be applied even to a sewing machine, an embroidery machine or the like.

First, a configuration example of a sewing machine 100 according to the present embodiment will be described based on FIGS. 1 to 5. However, in FIGS. 1 to 5, in the right-handed XYZ coordinates, the direction in which the sewing needle moves up and down is the Z axis direction, the direction orthogonal to the Z axis direction is the X axis direction, and the Z axis direction and the X axis direction The direction orthogonal to both is taken as the Y-axis direction. The X-axis direction is equal to the longitudinal direction of the bed described later.

The main part of the sewing machine 100 shown in FIG. 1 includes a housing mechanism P0, a transport mechanism P1 whose details are shown in FIG. 2, a control device P2, and a sewing mechanism P3 shown in FIG.

As shown in FIG. 1, the casing mechanism P0 of the sewing machine 100 includes an arm 101 for storing the upper shaft included in the sewing mechanism P3 of FIG. 3 and a spindle motor case 102 for housing the spindle motor connected to the upper shaft. A sewing machine head 103 in which a sewing mechanism P3 performs a sewing operation at a tip end of an arm 101, a bed 104 for storing an XY stage included in a transport mechanism P1, and support legs 105 for supporting the arm 101 and the bed 104 from an installation floor And a sliding plate 106 fixed to the upper surface of the bed 104 and slidably supporting the holding device 112 included in the transport mechanism P1 on a plane.

The housing mechanism P0 is a high rigidity steel plate designed to withstand mechanical breakage due to an impact when the sewing machine 100 operates, or a flexible material that disperses and absorbs the impact such as steel sheet or casting. Configure.

Although the spindle motor case 102 is connected to one end of the arm 101 in FIG. 1 in order to clearly show the disposition of the spindle motor, the spindle motor 201 of FIG. Also good. The spindle motor 201 shown in FIG. 3 may be installed integrally with the sewing machine head 103, not inside the arm 101.

As shown in FIG. 1, the transport mechanism P <b> 1 of the sewing machine 100 includes an XY stage 111 and a holding device 112. The XY stage 111 is driven in the X-axis direction and the Y-axis direction by the X-axis motor 113 and the Y-axis motor 114 in FIG. 2, and the holding device 112 connected to the movable portion of the XY stage 111 is on the horizontal surface of the slide plate 106 Transport

In the present embodiment, the X-axis motor 113 and the Y-axis motor 114 are servomotors mounted on the side of the bed 104, and drive the X-axis drive mechanism 115 and the Y-axis drive mechanism 116, respectively. As shown in detail in FIG. 2, the XY stage 111 uses the X-axis motor 113 and the Y-axis motor 114 as drive sources in the X-axis direction and the Y-axis direction, respectively, and holds the holding device 112 coupled to the movable portion of the XY stage 111. The sheet is transported in the horizontal plane on the slide plate 106. The X-axis drive mechanism 115 uses a movable race 115a to which the holding device 112 is connected as a movable portion, and the Y-axis drive mechanism 116 uses a Y-axis guide 116a to which the holding device 112 is connected as a movable portion.

The X-axis motor 113 and the Y-axis motor 114 are attached with

rotation information detectors

117 and 118, respectively, which detect rotation information such as the angle and angular velocity of the rotor with respect to the stator. In the present embodiment, the

rotation information detectors

117 and 118 are described as being optical encoders that detect the angle of the rotor with respect to the stator. The angular velocity and angular acceleration of the rotor can be obtained by differentiating the detected angle signal.

The holding device 112 connected to the XY stage 111 includes a pressing stand 112 a, a feed plate 112 b, an outer pressing 112 c, and an air cylinder 112 d. The presser stand 112a is connected to the moving race 115a, the Y-axis guide 116a, and the XY stage 111, and the slide plate 106 on the other end is connected to the feed plate 112b and the outer presser 112c. The feed plate 112 b is disposed on the upper surface of the slide plate 106, and slidably moves on the slide plate 106 as the XY stage 111 is driven. An object to be sewn, which is an object forming a seam by the sewing machine 100, is disposed between the feed plate 112b and the outer presser 112c, and the outer presser 112c presses the feed plate 112b vertically downward to hold the holding device 112. Is held by

The holding device 112 switches between holding and non-holding of the workpiece using the air cylinder 112 d as a drive source. The holding device 112 performs a conveying operation for holding and conveying the material to be sewn such that the insertion position of the sewing needle with respect to the material to be sewn is a specific position designated by the user of the sewing machine 100.

In the present embodiment, the air cylinder 112d is used to adjust the air pressure in order to secure the holding force of the holding device 112, but the invention is not limited to this, and the sewing material is held using an electromagnetic press or a hydraulic press. You may. Further, the configuration of the transport mechanism P1 is not limited to that shown in FIG. 2. For example, other types of sewing machines that transport the sewing material to the sewing needle by the feed teeth or a sewing machine that transports the sewing material by the robot The upper thread tension detection method described in the embodiment can be applied. Further, although in FIG. 2 the X-axis drive mechanism 115 and the Y-axis drive mechanism 116 are configured by a belt pulley mechanism, the invention is not limited to this, and a ball screw mechanism or a ball spline mechanism may be used. Further, the drive source of the XY stage 111 is not limited to the rotating electrical machine, and a plurality of linear motors, planar motors, spherical motors, etc. may be used.

A control device P2 of the sewing machine 100 includes an operation panel 121, a control panel 122, and a foot switch 123. A user of the sewing machine 100 gives a sewing command signal for driving the sewing machine 100 from the operation panel 121 to the control panel 122 based on sewing data such as sewing pattern data created on the operation panel 121. The control panel 122 controls the conveyance operation by the conveyance mechanism P1, and further controls the speed and timing of the sewing operation by the sewing mechanism P3 described later. The foot switch 123 receives an operation that the user of the sewing machine 100 presses a button, a touch panel, or the like, and starts an operation start signal to start the sewing operation by the sewing machine 100; A holding signal for switching is output to the control board 122. The operation of the control device P2 will be described after the details of the sewing mechanism P3 are described.

Next, details of the sewing mechanism P3 of the sewing machine 100 according to the present embodiment will be described using FIGS. 3 to 5. As shown in FIG. 3, the sewing mechanism P3 pulls the needle thread from the sewing material by means of a needle 132 having a needle hole, a hook 132 for catching the needle thread and entangleing the needle thread and the bobbin thread. A balance 133 which performs seam tightening to be formed, a spindle motor 134 which is a driving source for driving the sewing needle 131 and the hook 132 and the balance 133, a middle presser 135 which prevents floating of a sewing material, and a middle presser 135 And a middle pressing motor 136 which is a driving source. Further, as shown in FIG. 5B, the sewing mechanism P3 includes a pre-tension 162 and a main tension 163 for adjusting the tension of the upper thread.

The sewing needle 131 has a needle hole 131a through which an upper thread serving as an upper thread is formed when forming a stitch, and moves up and down in the Z-axis direction using the spindle motor 134 as a drive source. The sewing needle 131 descends from the top dead center and reaches the bottom dead center after being inserted into the sewing material, and then the sewing material is sewn while the sewing needle 131 rises from the bottom dead center to the top dead center You are pulled out of the The sewing needle 131 cooperates with the hook 132 after reaching the bottom dead center and before the needle is pulled out from the sewing material, and when forming a stitch, a lower thread which is a lower thread of the sewing material and Tangle the upper thread. Thereafter, the needle thread 131a of the sewing needle 131 is pulled out of the material to be sewn, whereby the upper thread is pulled out to the upper surface of the material to be sewn.

A rotation information detector 137 is attached to the spindle motor 134 to detect rotation information such as the angle and angular velocity of the rotor with respect to the stator. In the present embodiment, the rotation information detector 137 is described as an optical encoder that detects the angle of the rotor with respect to the stator of the spindle motor 134. The spindle motor 134 is fixed to the arm 101, and one end of a shaft-shaped upper shaft 139 is coupled to the rotor of the spindle motor 134 via a coupling 138.

The rotational movement of the upper shaft 139 is converted to the vertical movement of the needle bar 142 through the balance drive mechanism 140 and the needle bar drive mechanism 141 mounted on the other end of the upper shaft 139 to which the coupling 138 is not connected. . A sewing needle 131 is attached to the tip of the needle bar 142, and along with the vertical movement of the needle bar 142, the sewing needle 131 moves up and down in the Z-axis direction. The needle bar drive mechanism 141 for moving the sewing needle 131 up and down with the main spindle motor 134 as a drive source is constituted by a needle bar crank, a connecting bar, a needle bar holding, etc. The other description using and the like is omitted.

The kettle 132 is comprised of an outer kettle having a sword tip, a bobbin wound with a lower thread, and a bobbin case 143 for housing the bobbin so as to prevent the bobbin from falling out of the outer kettle. In the present embodiment, a case is shown in which a full-turn furnace is adopted as the furnace 132, but the present invention is not limited to this. For example, the barrel 132 may be half a turn, or it may be horizontal or vertical.

The iron 132 uses the spindle motor 134 as a drive source. In FIG. 3, an upper shaft pulley 144 is concentrically mounted on the upper shaft 139 near one end of the upper shaft 139 and the coupling portion of the coupling 138, and the upper shaft pulley 144 on the driving side is a timing belt 145. The lower shaft pulley 146 on the driven side is rotated. The lower shaft pulley 146 rotates the large diameter gear 147 via the shaft and rotates the small diameter gear 148 engaged with the large diameter gear 147. By configuring in this manner, the shaft-shaped lower shaft 149 connected to the small diameter gear 148 rotates at a double speed with respect to the upper shaft 139. The bite 132 and the lower shaft 149 are connected to the lower shaft 149 at the end of the shaft where the small diameter gear 148 is not fitted, and the bite 132 moves the sewing needle 131 up and down by the rotation of the spindle motor 134 Rotate at twice the frequency. At this time, the point of the biting needle 132 is such that the sewing needle 131 is lowered and inserted into the sewing material, and after reaching the bottom dead center, it is rising toward the top dead center. The loop formed by the upper thread passed through the needle hole is captured. The configuration of the full rotation oven is a well-known technology, so other explanations using an enlarged view etc. will be omitted.

The balance 133 uses a main spindle motor 134 as a drive source, and is connected to a balance drive mechanism 140 configured by a crank and a balance rod. The balance 133 is a rigid body of a metal material in the shape of a bell crank, and has one end provided with a small hole 133a for inserting an upper thread at one end, and the other end rotated with respect to the crank connected to the upper shaft 139 Connectable. The other end of the balance rod, one end of which is rotatably connected to the arm 101, is connected to the bent portion in the bell crank shape. With this configuration, the balance 133 is driven by the upper shaft 139 that rotates in synchronization with the spindle motor 134, and one cycle of vertical movement of the sewing needle 131 and the balance 133 becomes equal. The small hole 133a of the balance 133 is normally driven to reach the top dead center when the rotation angle of the spindle motor 134 is delayed by about 60 degrees from the top dead center of the sewing needle 131. The configuration of the balance drive mechanism 140 for driving the balance 133 is a well-known technology, and thus other descriptions using an enlarged view and the like will be omitted.

Next, a drive mechanism of the middle presser 135 according to the present embodiment will be described with reference to FIG. The middle presser 135 uses the middle presser motor 136 including the rotation information detector 150 as a drive source, and is connected to the middle presser drive mechanism 151. The middle pressing drive mechanism 151 drives a PF (Pressure Foot) axis of the sewing machine 100. The presser motor 136 includes a rotation information detector 150 to detect the angle or speed of the rotor with respect to the stator of the presser motor 136. In the present embodiment, the rotation information detector 150 is described as an engineered encoder that detects the angle of the rotor with respect to the stator.

The middle pressing drive mechanism 151 includes a pinion 152, a rack 153, a slide guide 154, a slider 155, a middle pressing rod holder 156, and a middle pressing rod 157.

In the present embodiment, the middle pressing motor 136 is a servomotor fixed to the arm 101, and a small circular hole provided at the center of the small diameter circular gear shaped pinion 152 is fitted to the rotor thereof. There is. The teeth of the pinion 152 mesh with the teeth of the rack 153 and convert the rotational movement of the presser motor 136 into a translational movement of the rack 153. The rack 153 is connected to the slider 155, and the slider 155 is guided by the slide guide 154 so as to slide up and down in the Z-axis direction. A middle presser bar clamp 156 is fastened to the slider 155 with a bolt, and the middle presser bar 157 is inserted into the middle presser bar clamp 156 and is compacted. The middle presser 135 is attached to the tip of the middle presser bar 157, and the middle presser bar 157 moves up and down in the Z-axis direction to drive the middle presser 135 in the vertical direction. A circular through hole 135a is provided at the tip of the middle presser 135, and a sewing needle is inserted through the through hole 135a. With such a configuration, the sewing machine 100 drives the height of the middle presser 135 independently of the other sewing mechanisms by controlling the rotation of the middle presser motor 136.

In this embodiment, a rotary servomotor, that is, a rotary electric machine having an annular stator and a cylindrical rotor, is used as the middle presser motor 136, and the rotational motion of the rotor is controlled by the rack and the pinion. Convert to translational motion. However, the drive source of the inner presser 135 is not limited to a rotating electrical machine such as a servo motor or a stepping motor, and may be an actuator that directly realizes translational drive such as a linear motor or a voice coil motor. By using these, it is possible to reduce the loss of power transmission ratio by the rack and pinion mechanism. In addition, since the effects of backlash and friction are reduced by simplifying the mechanism, it is possible to make it easy to grasp the external force that the middle presser 135 receives from the outside from the behavior of the actuator.

Next, based on FIGS. 5A and 5B, a sewing mechanism related to control of the upper thread path and tension of the sewing machine 100 will be described. FIG. 5A is an overall view showing the entire upper thread path in the sewing machine 100, and FIG. 5B is an enlarged view showing the upper thread path in the sewing machine head 103.
Before the sewing operation is performed by the sewing machine 100, the user of the sewing machine 100 sews the upper thread T, which is the upper thread when forming the seam, from the thread winding 159 which is the supply source of the upper thread T, Feed along the upper thread path to the needle 131. The upper yarn path starts from the yarn winding 159 erected on the yarn winding stand 158, the upper yarn guides 160 and 161, the pretension 162, the main tension 163, the small hole 133a of the balance 133, and the upper yarn guides 164 and 165, A needle hole 131 a provided at the tip of the sewing needle 131 is taken as an end point via 166 in order. Since the sewing needle 131 is inserted into the through hole 135a provided in the cylindrical portion at the tip end of the middle pressing portion, the upper thread T inserted into the needle hole 131a is also inserted into the through hole 135a. The upper thread guides 160, 161, 164, 165, and 166 are through holes through which the upper thread T is inserted, and guides the upper thread T along the arm 101 so that the upper thread T does not get entangled or unraveled. The tension of the upper thread T is applied by a spring which is a component of the pre-tension 162 and the main tension 163 and a plate for holding the thread.

Next, a control configuration of the sewing machine 100 according to the present embodiment will be described using FIG. FIG. 6 is a block diagram showing a control configuration of the sewing machine according to the first embodiment. The control panel indicated by reference numeral 122A corresponds to the control panel 122 shown in FIG.

As shown in FIG. 6, the control panel 121 of the sewing machine 100 includes a display 121a, a processor 121b, a storage device 121c for storing sewing pattern data D1, and an input device 121d. The user of the sewing machine 100 inputs the sewing pattern data D1 for each needle by operating the input device 121d configured by a push-down button or a touch panel while referring to the display 121a. As a result, the sewing pattern data D1 is stored in the storage device 121c. The operating system of the control panel 121 is operated by the processor 121 b. By using the sewing pattern data D1 stored in the storage device 121c, creation, editing and copying of the sewing pattern become easy.

The sewing pattern data D1 created on the control panel 121 is converted into a sewing command signal by the processor 121a and transmitted to the command generation unit 1A1 of the control panel 122A. The sewing pattern data D1 is data that determines the position and shape of the stitches formed on the workpiece and the operation speed of the sewing machine 100. Transmission of signals between the control panel 121 and the control panel 122A is performed via a communication circuit (not shown).

The indicator 121a of the control panel 121 receives the tension monitoring signal output from the PF-axis motor control calculation unit 1A3 of the control panel 122A as input, and detects the occurrence of thread breakage based on the tension monitoring signal and forms the same seam If the upper thread tension fluctuates for each needle despite the fact that the sewing operation is performed, the occurrence of the sewing failure is displayed to the user of the sewing machine 100.

The display 121a is not limited to the one provided inside the control panel 121, and may be a display such as a liquid crystal panel or a traffic signal present outside the control panel 121. In this case, communication between the display and the control panel 122A may be either wired communication or wireless communication. Also, the display 121a may be included in the control panel 122A. Similarly, the storage device 121 c is not limited to one provided inside the operation panel 121, and a storage device existing outside the operation panel 121 can be used. In this case, communication between the storage device and the control panel 122A may be either wired communication or wireless communication.

As shown in FIG. 6, the control panel 122A for controlling the sewing machine 100 includes at least a command generation unit 1A1, a spindle motor control calculation unit 1A2, a PF axis motor control calculation unit 1A3, and an X axis motor control calculation unit 1A4. And Y-axis motor control calculation unit 1A5. In addition to these, it has a control circuit and a power supply circuit that drive a solenoid that performs thread cutting when sewing is completed, a notification sensor that notifies that the thread is lost, a position sensor for performing return-to-origin with the transport mechanism P1, and the like. In some cases, these are not directly related to the effects of the present invention, and thus the description thereof is omitted.

Control panel 122 A is a spindle motor output from rotation information detector 137 of spindle motor 134, a sewing command signal output from processor 121 b of operation panel 121, a holding signal and operation start signal output from foot switch 123, and The spindle rotation signal which is the rotation information of 137, the PF axis rotation signal which is the rotation information of the inner pressing motor 136 outputted from the rotation information detector 150 of the inner pressing motor 136, and the rotation information detector 117 of the X axis motor 113 An X-axis rotation signal, which is rotation information of the X-axis motor 113 output from the Y-axis motor 114, and a Y-axis rotation signal output from the rotation information detector 118 of the Y-axis motor 114 are input.

The control board 122A controls the spindle control current for driving the spindle motor 134, the PF axis control current for driving the middle presser motor 136, and the X axis control current for driving the X axis motor 113 based on these input signals. A Y-axis control current for driving the Y-axis motor 114, a holding command signal for driving the air cylinder 112d, and a tension monitoring signal output from the PF-axis motor control calculation unit 1A3 are output.

The command generation unit 1A1 of the control panel 122A receives the sewing command signal output from the processor 121b of the control panel 121, the holding signal and the operation start signal output from the foot switch 123, and the spindle command signal PF An axis command signal, an X axis command signal, a Y axis command signal, and a holding command signal are output. The spindle command signal, the PF axis command signal, the X axis command signal, and the Y axis command signal respectively represent the rotation angles of the spindle motor 134, the inner press motor 136, the X axis motor 113, and the Y axis motor 114. It is an electrical signal to be specified, and is calculated inside the command generation unit 1A1 according to the sewing pattern data D1.

The holding signal output from the foot switch 123 is an electric signal that designates the pressure of the air cylinder 112 d so that the sewing material is held by the feed plate 112 a and the outer presser 112 b of the holding device 112. As the operation start signal output from the foot switch 123, the command generation unit 1A1 controls the spindle command signal, the PF axis command signal, the X axis command signal, and the Y axis command signal, and the spindle motor control operation unit 1A2 It is an electric signal which designates the timing which starts transmission toward PF axis motor control operation part 1A3, X axis motor control operation part 1A4, and Y axis motor control operation part 1A5.

Spindle motor control calculation unit 1A2 of control board 122A receives spindle command signal and spindle rotation signal and outputs spindle control current for rotating spindle motor 134 so that the difference between spindle command signal and spindle rotation signal becomes zero. .

The PF axis motor control calculation unit 1A3 of the control board 122A receives the PF axis command signal and the PF axis rotation signal and rotates the middle pressing motor 136 so that the difference between the PF axis command signal and the PF axis rotation signal becomes zero. Outputs PF axis control current. Further, the PF-axis motor control calculation unit 1A3 monitors the tension of the upper thread during a period in which the small hole 133a of the balance 133 rises with the rotation of the spindle motor 134, and outputs an upper thread tension monitoring signal. That is, the sewing machine 100 according to the present invention is configured such that the PF axis motor control calculation unit 1A3 monitors the upper thread tension.
The X-axis motor control calculation unit 1A4 of the control board 122A receives the X-axis command signal and the X-axis rotation signal and rotates the X-axis motor 113 so that the difference between the X-axis command signal and the X-axis rotation signal becomes zero. Outputs X-axis control current.

The Y-axis motor control calculation unit 1A5 of the control panel 122A receives the Y-axis command signal and the Y-axis rotation signal and rotates the Y-axis motor 114 so that the difference between the Y-axis command signal and the Y-axis rotation signal becomes zero. Outputs Y-axis control current.

Next, an operation in which the sewing machine 100 forms a stitch will be described. First, the user of the sewing machine 100 supplies the upper thread T from the thread winding 159 to the needle hole 131a along the above-described upper thread path. On the other hand, the lower thread Td, which is the lower thread when forming the seam, is wound around the bobbin stored in the bobbin case 143 of the hook 132.

Then, when the user of the sewing machine 100 presses the foot switch 123 and the holding signal is sent to the command generating unit 1A1 of the control panel 122A, the air cylinder 112d is activated by the holding command signal output from the command generating unit 1A1. The sewing material is nipped by the holding device 112 shown in FIG. 1 so that it can be conveyed. Thereafter, when the foot switch 123 is further depressed and an operation start signal is sent to the control panel 122A, the X-axis motor 113 and Y-axis motor 114 as drive sources of the transport mechanism P1 and the main shaft as drive sources of the sewing mechanism P3. The motor 134 and the middle pressing motor 136 are activated, and the sewing machine 100 starts to form a stitch at a specific position of the material to be sewn that the user of the sewing machine 100 has designated in advance with the operation panel 121. Thus, when the spindle motor control calculation unit 1Ab of the control panel 122A rotates the spindle motor 134, the sewing needle 131 having the needle thread T passing through the needle hole 131a is directed from the upper side to the lower side of the sliding plate 106 Needle is inserted into the workpiece. The upper thread T is supplied to the lower side of the workpiece by the operation of the sewing needle 131. Thereafter, when the sewing needle 131 ascends from the bottom dead center, the upper thread T forms a loop on the lower side of the sewing material due to the friction with the sewing material.

The point of the hook 132 catches the upper thread at the timing at which the loop of the upper thread T is formed, and entangles the upper thread and the lower thread. The timing at which the point of the hook of the hook 132 catches the upper thread is generally from 190 degrees to 210 degrees for the rotation angle of the spindle motor, assuming that the rotation angle of the spindle motor when the sewing needle is at top dead center is 0 degrees. It is set within the range. After the upper thread and the lower thread are intertwined, the upper thread is pulled out to the upper surface of the material to be sewn by pulling out the sewing needle 131 from the material to be sewn. Then, the upper thread T is tightened by pulling up the upper thread above the sewing material to form a seam. At this time, the middle presser 135 presses the material to be sewn so that the material to be sewn does not lift up or flap as the sewing needle 131 and the balance 133 rise.

Then, the pretension 162 and the main tension 163 always apply a constant tension to the upper thread during a period in which the sewing machine 100 forms a stitch.

Next, the detection operation of the upper thread tension of the sewing machine 100 according to the first embodiment of the present invention will be described with reference to FIGS. 7 to 13.

First, based on FIGS. 7-9, the characteristic of the operation | movement at the time of the sewing machine 100 which concerns on this Embodiment detecting an upper thread | yarn tension compared with operation | movement of a general electronic sewing machine is demonstrated.

FIG. 7 and FIG. 8 show the sewing needle when the sewing needle descends from the top dead center to the bottom dead center and moves again to the top dead center in the general electronic sewing machine and the sewing machine 100 according to the present embodiment. The positional relationship between the presser and the workpiece and the formed seam are shown. In both figures, the stitches up to the (N-1) th stitch are already formed, and thereafter the sewing needle descends to perform the sewing operation of the Nth stitch.

FIG. 9 is a timing chart depicting driving loci of sewing needles and middle pressers in a general electronic sewing machine and the sewing machine 100 of the present invention. The timing a shown by the broken line in FIG. 9 is the top dead center of the sewing needles 131 'and 131 in the sewing operation of the (N-1) th stitch, the timing b is the insertion of the sewing needles 131' and 131, the timing c is the sewing needle At the bottom dead center of 131 'and 131, timing d is the rotation angle of the spindle motor at the time of withdrawal of the sewing needles 131' and 131 when timing is as follows. Similarly, timings a ′ to e ′ indicate timings when the sewing machine 100 performs the sewing operation of the N th stitch. 7 and 8 show the operation state when the rotation angle of the spindle motor is at timing a 'in the timing chart of FIG. The black circle (●) mark in the upper part of FIG. 9 explicitly indicates the position of the sewing needle at the timing d when the loop goes around the upper thread loop.

As shown in the upper part of FIG. 9, the sewing needles 131 'and 131 move up and down in a stroke lh. Further, as shown in the middle and lower parts of FIG. 9, the middle pressers 135 'and 135 move up and down with the stroke lo. However, the waveforms in the middle and lower parts of FIG. 9 indicate the drive waveforms of the bottom of the middle presser 135, and the middle presser 135 is a timing e at which the sewing needles 131 'and 131 are withdrawn from the sewing material and inserted again. , And b ', the bottom surface of the middle presser 135 is driven to stop at a position raised by a distance dlo from the workpiece. The distance dlo is at least longer than the diameter of the upper thread T so that the upper thread T can pass between the middle presser 135 and the workpiece Ob.

In FIG. 7, the inner presser 135 'of a general electronic sewing machine is driven in a sine wave of almost the same phase as the drive trajectory of the sewing needle 131'. For this reason, when the sewing needle 131 'is located at the top dead center, the sewing needle 131' is located at a position further away than the sewn article Ob 'compared to FIG. More specifically, as shown by the open circle (o) in the middle of FIG. 9, the inner presser 135 'of the general electronic sewing machine is sewn at timing d when the hook tip of the hook takes over the upper thread loop. It is driven with a sinusoidal trajectory so as to press an object. In particular, when the middle presser 135 'uses a main spindle motor as a drive source in a general electronic sewing machine, it is difficult to realize the drive pattern of the middle presser as shown in the lower part of FIG. On the other hand, in FIG. 8, since the middle presser 135 is independently driven by the middle presser motor 136, the distance between the middle presser 135 and the workpiece Ob at the timing a 'at which the sewing needle 131 is located at the top dead center. It can be stopped at a position separated by dlo.

By the way, in the upper thread T 'or the upper thread T, tension is generated between the sewn article Ob' and the small hole as the small hole of the balance rises. The main object of the present invention is to guarantee the sewing quality by detecting the magnitude of the tension based on the behavior of the inner presser motor 136 during the sewing operation without adding a dedicated detector. Therefore, the sewing machine 100 according to the present invention drives the transport mechanism P1 for holding the workpiece Ob so that the upper thread T and the middle presser 135 are in contact with each other. Then, as shown in FIG. 8, the upper presser foot 135 is stopped at a position separated by a distance dlo from the workpiece Ob during a period in which the small hole of the balance is lifted, whereby the upper thread T 'is higher than the upper thread T'. The present invention is characterized in that the influence of the load exerted on the middle presser motor 136 is increased.

Next, based on FIG. 10, the sewing operation and the conveying operation when the sewing machine 100 according to the present embodiment detects the upper thread tension will be described.

FIG. 10 shows the drive of the driven object at the (n-1) th and subsequent stitches when the sewing machine 100 repeatedly performs the sewing operation of n stitches or more (n ≧ 3) on the workpiece Ob on the upper surface of the slide plate 106. Indicates a waveform. More specifically, in the figure, sequentially from the top, the position of the needle hole 133a of the sewing needle 131, the rotation angle of the sword tip of the bar 132, the position of the middle presser 135, the position of the small hole 133a of the balance 133, and the transport mechanism P1. The position of the workpiece to be transported in the X-axis direction and the position of the workpiece to be transported by the transport mechanism P1 in the Y-axis direction are shown.

First, as shown in the top row of FIG. 10, the needle hole 131a of the sewing needle 131 having the spindle motor 134 as a drive source draws the same trajectory as that of FIG. Needle insertion, bottom dead center at timing c, needle withdrawal from the workpiece at timing e. The timing d is when the tip of the hook 132 crawls the upper thread loop, and the black circle (●) marks indicate the position of the sewing needle 131 at this time. Further, as in FIG. 9, the stroke of the sewing needle 131 is lh.

Next, the second stage from the top of FIG. 10 shows the rotation angle of the bite 132 with the spindle motor 134 as the drive source, and the drive waveform of the bite 132 is a sine wave of amplitude l k. In the present embodiment, since the full rotation bite is adopted, the rotational waveform of the bite 132 is twice as high in frequency as the position waveform of the sewing needle 131. The black circle (●) mark in the figure positively indicates the rotation angle of the bite 132 when the tip of the bite 132 crawls the loop formed on the upper thread. The upper thread T captured by the tip of the hook 132 is released from capture by the hook 132 at timing i when the hook 132 counts from the rotation angle a one and a half rotations.

Next, the third row from the top of FIG. 10 shows the position waveform of the small hole 133 a of the balance 133 which uses the spindle motor 134 as a drive source. The small hole 133a of the balance 133 is driven such that one rotation of the spindle motor 134 is one cycle, the top dead center is at the timing h of the spindle motor 134, and the bottom dead center is at the timing i. The timing h is by mechanically adjusting the rotation center at which the balance drive mechanism 140 swings, from when the spindle motor 134 starts rotating until the sewing needle 131 is inserted into the workpiece Ob, ie, the spindle The rotation angle of the motor 134 is designed to exist between a and b. In the present embodiment, the timing h is an angle at which the spindle motor 134 has rotated 60 degrees from the timing a.

On the other hand, the timing i at which the small hole 133a reaches the bottom dead center is the timing at which the rotation angle of the barrel 132 is one and a half from a. This is because, at the rotation angle i of the spindle motor 134, the complementing of the upper thread by the bite 12 starts to be released. If the small hole 133a is pulled up before the complement of the upper thread by the hook 132 is released, the upper thread T can not withstand the tension generated when the balance 133 is raised, or the upper thread is unwound or The problem of thread breakage occurs. Further, in the present embodiment, the timing i is an angle obtained by rotating the spindle motor 134 by 270 degrees from the timing a. Therefore, the small hole 133a of the balance 133 falls in a period td from the timing h to the timing i during the sewing operation of the (N-1) th stitch, and in a period tu from the timing i to the timing h 'of the Nth needle. To rise. There is a relationship of td> tu between the period td and the period tu.

Next, the fourth row from the top of FIG. 10 shows the position of the bottom portion of the middle presser 135 using the middle presser motor 136 as a drive source, as in the lowermost stage of FIG. The middle presser 135 starts lowering from the top dead center by the rotation of the middle presser motor 136, and the upper surface of the sewn article Ob until the timing b when the sewing needle 131 is inserted into the sewn article Ob. Drive to abut on. When the sewn article Ob is formed of a non-stretchable material, the middle presser 135 presses the sewn article Ob at the height when the middle presser 135 descends and abuts on the sewn article Ob. In this case, the bottom dead center of the middle presser is the height when the bottom portion of the middle presser 135 abuts on the sewn article Ob, and the middle presser 135 moves up and down with stroke lo from the top dead center to the bottom dead center. Do.

When the sewn article Ob is formed of a material having high elasticity, the middle presser 135 descends and the middle presser 135 presses the sewn article Ob at a height at which the sewn article Ob is compressed. In this case, the bottom dead center of the middle presser is the height when the sewn article Ob is compressed. Then, the middle presser 135 starts pressing the material to be sewn Ob before the sewing needle 131 is inserted into the material to be sewn Ob and ascends the distance dlo from the material to be sewn Ob after the needle 131 is withdrawn. .

Next, the fifth row from the top of FIG. 10 shows the position waveform of the holding device 122 driven by the X-axis motor 113 in the X-axis direction. Since the holding device 122 holds the workpiece Ob, this position waveform is equal to the position waveform of the workpiece Ob in the X-axis direction. The symbol lx in the figure is the movement distance of the holding device 122 moving in the X-axis direction between one needle. The holding device 122 stands still while the sewing needle 131 is being inserted into the sewing object Ob so that the sewing object Ob is not damaged or the needle breakage occurs, and the sewing needle 131 is moved from the sewing object Ob After the needle removal, it is driven until it is again inserted into the sewing material Ob.

In this embodiment, in order to detect the upper thread tension at the time of lifting the balance from the behavior of the middle pressing motor, the XY stage 111 so that the upper thread T contacts the middle pressing 135 while the small hole 133a of the balance 133 is lifted. Drive. Therefore, the X-axis motor 113 is driven from the timing e at which the sewing needle 131 is pulled out of the workpiece Ob to the timing i at which the small hole 133a starts to rise. Therefore, the X-axis motor 113 rotates for a period tm from the timing e to the timing i at the (N-1) th needle, and stops at a period ts from the timing i to the timing e 'for the Nth needle.

Next, the sixth row from the top of FIG. 10 is a position waveform of the holding device 122 driven by the Y-axis motor 114 in the Y-axis direction. Since the holding device 122 holds the workpiece Ob, this position waveform is equal to the position waveform of the workpiece Ob in the Y-axis direction. The symbol ly in the figure is the movement distance of the holding device 122 moving in the Y-axis direction between one needle. In the present embodiment, the Y-axis motor 114 is driven with the same position waveform as the X-axis motor 113.

When the workpiece Ob is ly driven with lx in the X-axis direction and the Y-axis direction, the movement distance L of the XY stage 111, that is, the pitch of the seam can be obtained by the following equation (1).

When the bottom of the through hole 135a of the middle presser 135 is a circle of radius r and the sewing needle 131 moves up and down at the center of the through hole 135a, if the movement distance L is larger than the radius r, the middle presser 135 and The XY stage can be driven so that the upper thread T contacts.

By reducing the angle θ formed by the sewing object Ob and the upper thread T shown in FIG. 14, the influence of the load exerted on the middle pressing motor 136 by the upper thread T can be increased. The angle θ can be obtained by Equation 2.

In order to reduce the angle θ, it is sufficient to increase (L−r) or to decrease the distance dlo for raising the middle presser.
(Tension detection operation by PF axis motor control calculation unit 1A3)

Next, the configuration and operation of detecting the load that the tension of the upper thread T applies to the middle presser motor 136 by the PF-axis motor control calculation unit 1A3 of the control panel 122A will be described in detail with reference to FIGS.

As shown in FIG. 11, the PF-axis motor control calculation unit 1A3 of the control panel 122A controls the rotation of the middle presser motor 136 at the time of sewing operation of the PF axis deviation suppression unit 1A3a, the current control unit 1A3b, and the sewing machine 100. And a tension monitoring unit 1A3c that monitors the yarn tension.

The PF axis deviation suppression unit 1A3a is a PF axis command signal that is a rotation command of the middle pressing motor 136 output from the command generation unit 1A1, and rotation information output from the rotation information detector 150 included in the middle pressing motor 136. PF axis motor that drives middle presser motor 136 so that the difference between the PF axis command signal and the PF axis rotation signal becomes 0 with the PF axis rotation signal and the tension monitoring signal output from tension monitoring unit 1A3 c as input Output a drive signal. The current control unit 1A3b generates a PF-axis control current for rotating the middle presser motor 136 based on the PF-axis motor drive signal, and supplies it to the middle presser motor 136. Then, the tension monitoring unit 1A3c detects the tension generated in the upper thread by the small hole 133a of the balance 133 moving upward based on the PF axis motor drive signal, and the indicator 121a of the operation panel 121 and the PF axis deviation suppressing means Output tension monitor signal to 1A3a.

As shown in FIG. 12, the PF axis deviation suppression unit 1A3a of the PF axis motor control calculation unit 1A3 includes a switch a1, a differentiator a2, and a deviation suppression compensator a3.

The switch a1 receives the PF axis command signal output from the command generation unit 1A1 and the tension monitoring signal output from the tension monitoring unit 1A3c as input, and thread breakage or upper thread tension occurs while the sewing machine 100 is performing the sewing operation When it is detected that the variation in the value of < ' > occurs, the change of the value of the PF axis command signal is stopped based on the tension monitoring signal to stop the middle pressing motor in conjunction with the occurrence of the sewing defect. By providing the same function as the switch a1 for the main spindle command signal, the X axis command signal, and the Y axis command signal, the operation of the entire sewing machine may be stopped in conjunction with the occurrence of the sewing defect. By doing this, it is possible to prevent the sewing machine 100 from performing an extra sewing operation after the occurrence of a sewing failure.

The subtractor a2 calculates a difference between the PF axis command signal output from the switch a1 and the PF axis rotation signal output from the rotation information detector 150, and outputs a deviation signal. The deviation suppression compensator a3 outputs a PF axis motor drive signal for driving the PF axis motor 136 so that the deviation signal converges to zero. The deviation suppression compensator a3 includes at least one of a proportional compensator performing proportional operation, an integral compensator performing integral operation, and a differential compensator performing differential operation to cause the deviation signal to converge to 0. . In this embodiment, PI control by a proportional compensator and an integral compensator is described as being adopted in the deviation suppression compensator a3.

Then, as shown in FIG. 13, the tension monitoring unit 1A3c of the PF-axis motor control calculation unit 1A3 includes a filter processing unit c1, a recording unit c2, and a comparator c3.

The filter processing unit c1 performs calculation to reduce the frequency component of the PF axis motor drive signal higher than the rotation frequency of the spindle motor 134 to improve the detection accuracy of the upper thread tension, and PF lower than the rotation frequency of the spindle motor 134 An evaluation signal is calculated and output by performing one or both of the operations for reducing the frequency component of the axis motor drive signal. In the filter processing unit c1, a phase filter for operating the phase of the PF axis motor drive signal or a proportional operation for changing the amplitude may be performed. By using the phase filter, it is possible to correct the detection delay and communication delay of the rotation information detector 150 and improve the accuracy of the tension detection time. Further, the evaluation signal can be normalized to an arbitrary detection specification by performing a proportional operation of changing the amplitude by multiplying the gain.

The recording unit c2 records an evaluation signal output from the filter processing unit c1 while performing a sewing operation one stitch before, and outputs the recorded evaluation signal in synchronization with the current sewing timing. That is, the recording unit c2 may be a delay computer that generates a delay corresponding to a time obtained by multiplying the time required for one hand.

The comparator c3 is a tension monitoring signal notifying that the rate of change of the current evaluation signal output from the filter processing unit c1 is larger or smaller than the threshold value with respect to the evaluation signal one stitch before output from the recording unit c2. Output

For example, when forming stitches in the same direction on a sewn article Ob having a predetermined shape, when the sewing operation and the conveying operation of the sewing machine 100 are normally performed and no sewing defect occurs, the upper thread T The load applied to the middle presser motor 136 via the middle presser 135 is uniform. In this case, the rate of change of the evaluation signal described above is small (ideally constant). On the other hand, when the rate of change of the evaluation signal described above is large, it is possible to detect that the upper thread tension for each needle is dispersed and that the thread tension and the tightening accuracy are not constant. Further, when no load is applied from the upper thread T to the middle pressing motor 136 and the evaluation signal becomes 0, since the upper thread T is not in contact with the middle pressing 135, occurrence of thread breakage can be detected. Thus, by setting the threshold value for the rate of change of the evaluation signal, it is possible to quantitatively evaluate the sewing quality based on the variation of the upper thread tension.

The comparator c3 may calculate feature amounts such as the maximum value, the minimum value, and the average value of the evaluation signal of the previous one-hand input, and compare it with the current evaluation signal. By doing this, it is possible to easily grasp the rate of change of the current evaluation signal with respect to the previous step. For example, the change rate normalizes the maximum value and the minimum value of the evaluation signal recorded in the period from the timing i of the (N-1) th needle to the timing h 'of the Nth needle to 100% and 0%. It can be calculated by evaluating how much the maximum value and the minimum value from the timing i ′ to the timing h ′ ′ of the (N + 1) th needle decrease by the comparator 703.

Moreover, it is desirable to set the above-mentioned threshold value in consideration of the variation for each needle caused by the sewing direction and the shape of the workpiece. In addition, the control panel 121 and the control panel 122A may be configured such that the user of the sewing machine 100 can set the threshold from the outside of the control panel 122A by the input device 121d through a preliminary test operation by trial sewing. For example, a configuration may be employed in which the threshold value is recorded in the storage device 121c of the control panel 121 and transmitted to the PF axis motor control calculation unit 1A3 of the control panel 121A through the processor 121b or a communication circuit (not shown). By doing this, it is possible to change the judgment criteria of the quality of the sewing quality in accordance with the request of the user of the sewing machine 100.

In addition, although the tension detection unit 1A3c receives the PF-axis motor drive signal as an input, the tension monitoring signal may be calculated and output using the PF-axis control current or the PF-axis rotation signal as an input.

Tension detection unit 1A3c forms a disturbance observer that receives a PF axis motor drive signal and a PF axis rotation signal, and is applied to middle presser motor 135 based on a mathematical model of middle presser motor 136 and a middle presser drive mechanism. Upper thread tension may be estimated.

In addition, the tension applied to the upper thread T by the pretension 162 and the main tension 163 may be controlled based on the tension monitoring signal so that the variation in needle thread tension of the upper thread is reduced.

As described above, the sewing machine 100 according to the first embodiment drives the sewn article Ob so that the upper thread T contacts the middle presser 135, and the upper thread is lifted while the small hole 133a of the balance 133 is lifted. Since T detects the load applied to the middle presser motor 136 via the middle presser 135 based on the PF axis motor drive signal, the upper thread tension applied to the upper thread by the rise of the small hole 133a causes the needle thread variation. It can be detected.

Therefore, the sewing machine 100 according to the first embodiment can form stitches while assuring sewing quality such as thread tension and threading accuracy with which it is possible to determine the quality based on the variation in upper thread tension.

Further, since the sewing machine 100 according to the first embodiment forms the seam while guaranteeing the sewing quality for each needle, it is possible to identify the seam in which the sewing failure has occurred.

The sewing machine 100 according to the first embodiment can detect thread breakage when no load is applied from the upper thread T to the middle pressing motor 136.

In addition, since the sewing machine 100 according to the first embodiment detects the upper thread tension based on the PF axis motor drive signal which is a drive control signal of the inner press motor 135, the sewing operation is performed with a simple configuration with few additional parts. It is possible to monitor the occurrence of thread breakage while doing, and to guarantee sewing quality such as thread tension and tightening accuracy.

In addition, the sewing machine 100 according to the first embodiment can easily secure the space around the arm and the ease of assembly compared to the case where a dedicated detector is provided in the upper thread path and upper thread tension is detected. The head design freedom can be expanded.

Second Embodiment
The configuration and operation of the sewing machine 100 according to the second embodiment will be described based on FIG. FIG. 14 is a timing chart showing the operation of the sewing machine according to the second embodiment.

The sewing machine 100 according to the second embodiment differs from the sewing machine 100 according to the first embodiment in the drive waveforms in the X-axis direction and the Y-axis direction of the holding device 112 driven by the XY stage 111 included in the transport device P1. The other configuration and operation are the same as those of the sewing machine 100 according to the first embodiment. Descriptions of similar parts will be omitted.

The XY stage 111 according to the first embodiment described above drives the X-axis motor 113 between timing e and timing i. Therefore, the number of rotations of the spindle motor 134 is high, and the sewing time of one needle is short. In the case where the moving distance L is long, it is necessary to drive the holding device 112 at high speed and high accuracy. As described above, in order to increase the speed and accuracy of the XY stage, it is necessary to increase the rigidity of the mechanism and the output of the driving source, which results in high cost. Therefore, in the present embodiment, the driving method of the holding device 112 is changed as follows.

As shown in the upper part of FIG. 14, the holding device 122 having the X-axis motor 113 as a drive source starts moving from timing e in the sewing operation of the (N−1) th stitch and moves by the timing b ′ of the N th stitch. Complete and stop. Therefore, the X-axis motor 113 stops at the period ts from the timing b to the timing e at the (N-1) th needle and rotates at the period tm from the timing e to the timing b 'of the Nth needle. The timing at which the holding device 122 stops may be within the period from the timing e to the timing b.

The lower part of FIG. 14 is a position waveform of the holding device 122 driven by the Y-axis motor 114 in the Y-axis direction. The Y-axis motor 114 rotates in a period tm in which the X-axis motor 113 rotates.

The sewing machine 100 according to the second embodiment can lengthen the drive time of the X-axis motor 113 and the Y-axis motor 114, so that the rotation speed of the spindle motor 134 is high and the sewing time of one needle is short. Even when the moving distance L is long, the load applied by the upper thread to the middle presser motor 136 via the middle presser 135 can be detected. Therefore, even in such a case, the sewing machine 100 according to the second embodiment can detect variations in needle thread tension applied to the upper thread by raising the small holes 133a. Stitches can be formed while guaranteeing sewing quality such as thread tension and tightness with which it is possible to judge the quality based on the variation in upper thread tension.

Third Embodiment
The configuration and operation of the sewing machine 100 according to the third embodiment will be described based on FIGS. 15 and 16. FIG. 15 is an image diagram showing a task of tension detection operation of the sewing machine according to the third embodiment. FIG. 16 is a timing chart showing the operation of the sewing machine according to the third embodiment.

The sewing machine 100 according to the third embodiment differs from the sewing machine 100 according to the first or second embodiment in the drive waveforms in the X axis direction and the Y axis direction of the holding device 112 driven by the XY stage 111 included in the conveyance device P1. The configuration and operation of the second embodiment are the same as the sewing machine 100 according to the first or second embodiment. Descriptions of similar parts will be omitted.

First, problems to be solved by the sewing machine according to the present embodiment will be described based on FIG. In the present embodiment, it is assumed that the diameters of the sewing needle 131 and the upper thread T are larger than those in the first and second embodiments described above. For this reason, in FIG. 15, the diameters of the sewing needle 131 and the upper thread T are made larger than in FIGS. 7 and 8, and the radius r of the through hole 135a of the inner presser 135 is drawn larger.

FIGS. 15A and 15B show the state of timing a ′ at which the sewing needle 131 becomes the top dead center when the sewing machine 100 is driven based on the timing chart (FIG. 10) of the first embodiment described above. It shows. In FIG. 15A, since the radius r of the through hole 135a is smaller than the movement distance L of the XY stage, if the XY stage is driven with the waveform pattern in the X axis direction and Y axis direction shown in the timing chart of FIG. At timing a ', the upper thread T contacts the middle presser 135 without any problem. Therefore, in FIG. 15A, while the small hole 133a of the balance 133 is lifted, the load applied to the middle presser motor 136 by the upper thread T via the middle presser 135 can be detected based on the PF axis motor drive signal. it can.

However, since the radius r is larger than the movement distance L in FIG. 15B, even if the holding device 122 is driven with the waveform patterns in the X-axis direction and the Y-axis direction shown in the timing charts of FIGS. The upper thread T can not be brought into contact with the bottom of the middle presser 135 when the small hole 133a is lifted. In order to bring the upper thread T into contact with the bottom of the middle presser 135, it is desirable to use an inner presser in which the radius r of the through hole 135a is minimum. In addition, it is not efficient and there is a limit to replacing the middle presser with the smallest radius r depending on the thickness of the upper thread T. Therefore, in the present embodiment, the drive pattern of the XY stage is changed as follows.

As indicated by the thick line in the upper part of FIG. 16, the holding device 122 having the X-axis motor 113 as the drive source forms the seam of the Nth stitch, and moves in the X axis direction from timing e in the conveyance operation of the (N-1) th stitch. Start and finish moving by time i and stop. The movement distance lxx at this time is made larger than the radius r of the through hole 135a so that the angle θ obtained by Equation 3 becomes 30 degrees or less.

Next, the holding device 122 stops the sewn article Ob so that the upper thread T contacts the bottom surface portion of the middle presser 135 by stopping in a period tss from the timing i to h 'when the small hole 133a of the balance 133 rises. Hold. Then, in a period from the timing h 'when the small hole 133a has finished rising to the timing b' when the sewing needle 131 is inserted into the workpiece Ob, the needle is moved to a predetermined position for forming the Nth stitch. Then, the holding device 122 stops in a period ts from the timing b 'at which the sewing needle 131 is inserted into the workpiece Ob to the timing e' at which the needle 131 is withdrawn. After timing e ′, the same operation is repeatedly performed to form the (N + 1) seam.

On the other hand, the thick line in the lower part of FIG. 16 shows the drive waveform in the Y-axis direction of the holding device 122 having the Y-axis motor 114 as a drive source. In the figure, the Y-axis motor 114 shows the same drive waveform as the X-axis motor.

Since the (N-1) th stitch and the Nth stitch are lx in the X-axis direction and ly in the Y-axis direction, the distance for moving from the timing h 'to the timing b' is the X-axis direction (lxx It becomes (lyy-ly) in the Y-axis direction, and the movement distance L 2 of the XY stage can be obtained by Expression 4.

Therefore, when the movement distance lxx in the X-axis direction is sufficiently larger than the radius r of the through hole 135a, it is not necessary to change the drive waveform of the Y-axis motor, and the movement distance lyy may be ly. That is, it is sufficient to determine lxx and lyy so that the distance L2 obtained by Equation 5 is sufficiently larger than the radius r.

When the number of rotations of the spindle motor 134 is high and the sewing time of one needle is short, or when the moving distance L of the XY stage 111 is long, the period from the timing e to i becomes short. For this reason, as shown by the thick broken line in FIG. 16, if the upper thread T contacts the bottom surface portion of the middle presser 135, the timing at which the holding device 122 stops within the period from timing e to timing h 'is changed. You may.

The sewing machine 100 according to the third embodiment is a small hole even when the radius r of the through hole 135a of the middle presser 135 is larger than the stitch pitch due to the thickness of the sewing needle 131 and the upper thread T. The holding device 122 is driven so that the upper thread T comes into contact with the bottom surface of the middle presser 135 during the period when 133 a moves up. Therefore, even in such a case, the sewing machine 100 according to the third embodiment can detect variations in needle thread tension applied to the upper thread by raising the small holes 133a. Stitches can be formed while guaranteeing sewing quality such as thread tension and tightness with which it is possible to judge the quality based on the variation in upper thread tension.

In the present embodiment, it is assumed that the through hole 135a of the middle presser 135 has a circular bottom portion with a radius r, but when using the middle presser whose shape of the bottom of the through hole 135a is not circular. Even if it is, quality assurance based on the upper thread tension detection means according to the present invention can be implemented.

Fourth Embodiment
The configuration and operation of the sewing machine 100 according to the fourth embodiment will be described based on FIGS. 17 and 18. FIG. 17 is a block diagram showing details of a PF axis motor control calculation unit of the sewing machine according to the fourth embodiment. FIG. 18 is a block diagram showing details of the PF axis deviation suppression unit of the sewing machine according to the fourth embodiment.

The sewing machine 100 according to the fourth embodiment differs from the sewing machine 100 according to the first to third embodiments in the data to be stored in the storage device 121c of the operation panel 121 and the PF axis deviation suppression unit 1B3a of the control panel 122B. The other configuration and operation are the same as those of the sewing machine 100 according to the first to third embodiments. Descriptions of similar parts will be omitted.

First, data that the sewing machine 100 according to the fourth embodiment communicates between the operation panel 121 and the control panel 121B will be described based on FIG. The storage device 121c of the control panel 121 stores the parameter D2 input by the user of the sewing machine 100 using the input device 121d, and outputs the parameter D2 to the control panel 122B. The parameter D2 is transmitted to the control panel 122B via a communication circuit (not shown) based on an instruction of the processor 121b included in the control panel 121. The PF axis deviation suppressor 1B3a of the control board 122B receives the parameter D2 and changes control parameters inside the PF axis deviation suppressor 1B3a.

Next, the details of the PF axis deviation suppression unit 1B3a will be described with reference to FIG. The PF axis deviation suppression unit 1B3a receives a PF axis command signal, a PF axis rotation signal, a tension monitoring signal, and a parameter D2 and outputs a PF axis motor drive signal. The deviation suppression compensator a3 of the PF axis deviation suppression unit 1B3a controls the rotation of the middle pressing motor 136 so that the difference between the PF axis command signal and the PF axis rotation signal becomes zero. In FIG. 18, assuming that PI control by a proportional compensator and an integral compensator is adopted as the deviation suppression compensator a3 and the deviation signal is Se and the PF axis motor drive signal is Sd, the transfer function of the deviation suppression compensator is It can be expressed.

Here, the symbol kp is a proportional control gain, the symbol Ti is an integration time constant, and the symbol s is a Laplace operator. The values of kp and Ti which are control parameters inside the PF axis deviation suppression unit 1B3a are changed based on the parameter D2 input from the outside.

Specifically, the parameter D2 manipulates the amplitude of the deviation signal Se by changing the proportional control gain kp, and manipulates the amplitude and phase of the deviation signal Se by changing the integration time constant Ti. In the sewing machine 100 according to the present embodiment, the middle presser 135 ascends from the workpiece Ob during a period in which the small hole 113a rises with the operation of the balance 133 after the hook 132 releases the capture of the upper thread T. During a period of contact with the upper thread T, the proportional control gain kp is made smaller or the integral time constant Ti is changed longer based on the parameter D2.

Since the sewing machine 100 according to the fourth embodiment reduces the proportional control gain kp or changes the integral time constant Ti long based on the parameter D2, the external force of the middle presser motor 136 is in a period when the upper thread T contacts the middle presser 135. The response to can be slowed. By doing this, it is possible to reduce the frictional force generated between the upper thread T and the middle presser 135 when the upper yarn T is pulled up with the middle presser 135 as a fulcrum. Therefore, when detecting the upper thread tension, PF axis deviation suppression portion 1B3a of sewing machine 100 according to the present embodiment prevents upper thread T from being cut or broken due to the frictional force with middle presser 135. The middle presser motor 136 can be driven.

Each function of the control panel of the sewing machine 100 according to the first to fourth embodiments can be realized using a processing circuit. The respective functions are the command generation unit 1A1 and the PF axis motor control calculation unit 1A3. FIG. 19 is a diagram showing a first hardware configuration example of a control board of a sewing machine according to the first to fourth embodiments. FIG. 20 is a diagram showing a second hardware configuration example of the control board of the sewing machine according to the first to fourth embodiments. FIG. 19 shows an example in which the above processing circuit is realized by dedicated hardware such as the dedicated processing circuit 190. FIG. 20 shows an example in which the above processing circuit is realized by the processor 191 and the storage device 192.

When dedicated hardware is used as shown in FIG. 18, the dedicated processing circuit 190 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an application specific integrated circuit (ASIC), an FPGA (field) A programmable gate array) or a combination thereof is applicable. Each of the above-described functions may be realized by a processing circuit, or may be realized collectively by a processing circuit.
When the processor 191 and the storage device 192 are used as shown in FIG. 20, each of the functions described above is realized by software, firmware or a combination thereof. The software or firmware is described as a program and stored in the storage device 192. The processor 191 reads out and executes the program stored in the storage device 192. It can also be said that these programs cause a computer to execute the procedures and methods performed by each of the above functions. The storage device 192 is a semiconductor memory such as a random access memory (RAM), a read only memory (ROM), a flash memory, an EPROM (registered trademark) (Erasable Programmable Read Only Memory), or an Electrically Erasable Programmable Read Only Memory (EEPROM). Do. The semiconductor memory may be a non-volatile memory or a volatile memory. In addition to the semiconductor memory, the storage device 192 corresponds to a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).

In the configuration shown in the embodiment described above, the load applied to the middle presser 135 from the upper thread is detected based on the PF-axis motor drive signal, but the present invention is not limited to this and the load applied to the middle presser 135 A detection element for detecting a load may be provided in the middle pressing drive mechanism 151.

The configuration shown in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and one of the configurations is possible within the scope of the present invention. Parts can be omitted or changed.

DESCRIPTION OF SYMBOLS 100 sewing machine, 101 arm, 102 main spindle motor case, 103 sewing machine head, 104 bed, 105 support leg, 106 slide plate, 111 XY stage, 112 holding device, 112a feed plate, 112b outer presser, 112c presser base, 112d air cylinder , 113 X axis motor, 114 Y axis motor, 115 X axis drive mechanism, 115a moving race, 116 Y axis drive mechanism, 116a Y axis guide, 117, 118, 137, 150 rotation information detector, 121 operation panel, 121a display , 121b, 191 processor, 121c, 192 memory device, D1 sewing pattern data, 121d input device, 122, 122A control panel, 123 foot switch, 1A1 command generation unit, 1A2 spindle motor control arithmetic operation unit, 1A3 PF axis motor control operation unit, 1A4 X axis motor control operation unit, 1A5 Y axis motor control operation unit, 131, 131 ′ sewing needle, 131a, 131a ′ needle hole, 132 bite, 133 balance, 133a, 131a ′ small hole, 134 spindle motor, 135, 135 'middle presser, 135a, 135a' through hole, 136 middle presser motor, 138 coupling, 139 upper shaft, 140 balance drive mechanism, 141 needle bar drive mechanism, 142 needle bar, 143 bobbin case, 144 upper shaft pulley, 145 timing belt, 146 lower shaft pulley, 147 large diameter gear, 148 small diameter gear, 149 lower shaft, 151 middle pressing drive mechanism, 152 pinion, 153 rack, 154 slide guide, 155 slider, 156 middle pressing bar Hugging, 157 pressed inside Bar, 158 pin winding stand, 159 pin winding, 160, 161, 164, 165, 166 upper thread guide, 162 pretension, 163 main tension, 190 dedicated processing circuit, a1 switch, a2 differencer, a3 deviation suppression compensator, c1 filter Processing unit, c2 recording unit, c3 comparator, T, T 'upper thread, Td, Td' lower thread, Ob, Ob 'material to be sewn.

Claims

A bite for entangling the upper thread and the lower thread by capturing the upper thread inserted into the needle hole of the sewing needle,
A balance having a small hole through which the upper thread is inserted, and the small hole raising the upper thread from a material to be sewn as the small hole rises from the bottom dead center to the top dead center;
An inner press to prevent lifting of the sewing material,
A drive source for driving the middle presser,
Transport means for transporting the sewing material;
A tension monitoring unit that monitors an upper thread tension based on a load applied from the upper thread to the middle presser when the upper thread contacts the middle presser when the transport means transports the sewn material; ,
Sewing machine equipped with
The sewing machine according to claim 1, wherein the tension monitoring unit detects the upper thread tension based on a load applied to the drive source.
3. The sewing machine according to claim 1, wherein the tension monitoring unit monitors the upper thread tension in a period from when the hook releases the upper thread until it reaches the top dead center.
The sewing machine according to any one of claims 1 to 3, wherein the tension monitoring unit outputs a sewing failure signal for notifying a sewing failure when the upper thread tension is larger or smaller than a reference value input from the outside.
The tension monitoring unit includes a recording unit that records the upper thread tension for each needle.
The sewing machine according to any one of claims 1 to 3, which outputs a sewing failure signal notifying sewing failure when the variation in the upper thread tension for each needle is larger or smaller than a reference value input from the outside.
The tension monitoring unit includes a recording unit that records the upper thread tension for each needle.
The sewing defect signal for notifying a sewing defect is output when the difference between the upper thread tension recorded by the recording unit and the upper thread tension monitored by the tension monitoring unit is larger than a set threshold value. The sewing machine according to any one.
A command to generate a drive command of the drive source to stop the inner presser at a certain height for the sewing material during a period when the small hole rises after the hook releases the capture of the upper thread The sewing machine according to any one of claims 1 to 6, comprising a generator.
And a deviation suppression unit that controls the drive source such that a deviation signal obtained from a difference between the drive state of the drive source and the drive command is zero.
Proportional operation for manipulating the amplitude of the deviation signal based on a parameter set from the outside of the deviation suppression unit during a period in which the small hole rises with the operation of the balance after the hook releases the capture of the upper thread The sewing machine according to claim 7, wherein the gain of the machine is reduced.
And a deviation suppression unit that controls the drive source such that a deviation signal obtained from a difference between the drive state of the drive source and the drive command is zero.
The amplitude and phase of the deviation signal are manipulated based on a parameter set from the outside of the deviation suppression unit during a period in which the small hole rises with the operation of the balance after the hook releases the capture of the upper thread. The sewing machine according to claim 7, wherein the integration time constant of the integration operator is increased.
A sewing failure is detected based on the upper thread tension monitored by the tension monitoring unit, and one or more of the sewing needle, the hook, the balance, the presser, and the conveying means are stopped. The sewing machine according to any one of Items 1 to 9.
The sewing machine according to any one of claims 1 to 10, further comprising an indicator for detecting a sewing failure based on the upper thread tension monitored by the tension monitoring unit, and displaying that the sewing failure has occurred.