Tatami sewing device

Abstract

To provide a tatami sewing device capable of detecting yarn breakage according to tatami thickness.SOLUTION: A tatami sewing device of an embodiment of the invention is a tatami sewing device to sew a tatami. The tatami sewing device has yarn breakage detection means to detect yarn breakage of a sewing yarn. The yarn breakage detection means has a detection sensor to detect yarn use amount, and control means. When actual yarn use amount of actually used yarn measured by the detection sensor is below a prescribed threshold according to a tatami thickness or needle height, the control means determines that yarn breakage has occurred.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a tatami mat sewing device for sewing tatami mats together, such as by sewing tatami mat edges to the sides of the tatami mats. [Background technology]

[0002] Conventionally, the manufacturing process of tatami mats involves a frame stitching process in which the tatami facing is sewn to the short side of the tatami mat, and a backstitching process in which the tatami edge is sewn to the long side of the tatami mat.

[0003] When sewing tatami mats, if the sewing thread breaks or frays during sewing due to some kind of problem, or if the sewing thread runs out, continuing to sew the tatami mat may result in a messy stitching or the stitches being moved forward. In such cases, the worker must replace the sewing thread by undoing it from underneath the tatami mat while it is still on the machine, which is extremely time-consuming. Furthermore, this can result in areas that cannot be sewn, leading to a poor finish.

[0004] Therefore, the applicant of the present application has previously proposed a thread breakage detection device for detecting thread breakage in sewing threads (see Patent Document 1). The thread breakage detection device of Patent Document 1 is provided with a speed detector 19 on the upper thread supply side for detecting the running speed of the upper thread when it is running, and is equipped with thread breakage determination means for comparing the upper thread running speed detected by this speed detector 19 with an upper thread lower limit speed set in advance in a speed setting device, and outputting a stop signal when the upper thread running speed is slower than the upper thread lower limit speed.

[0005] On the other hand, tatami mats of various thicknesses, such as thick tatami mats and thin tatami mats, are used depending on the location they are laid in. When manufacturing tatami mats of different thicknesses, if they are manufactured using the same settings, the stitching depth will not be consistent, resulting in unstable stitching strength and damage to sewing needles.

[0006] Therefore, when manufacturing tatami mats, it is necessary to change the height at which the sewing needle sews relative to the tatami mat depending on the thickness of the tatami mat. For example, Patent Document 2 discloses a tatami mat sewing device that changes the height at which the sewing needle sews relative to the tatami mat by rotating the sewing machine arm around the sewing machine arm shaft to accommodate the thickness of the tatami mat. In this tatami mat sewing device, rotation of the crank rotates the needle swing shaft via the crank rod and needle arm lever, causing the needle arm and sewing needle to move back and forth. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 63-234996 [Patent Document 2] Patent Publication No. 2006-394 Summary of the Invention [Problem to be solved by the invention]

[0008] The thread breakage detection device in Patent Document 1 is specialized for thick tatami mats and cannot be applied to thin tatami mats. Furthermore, the amount of thread used to sew thick and thin tatami mats differs, and if the thread breakage detection device in Patent Document 2 is applied to both thick and thin tatami mats, there is a risk of human error, such as incorrect measurement of tatami mat thickness, incorrect input of numerical values, or incorrect switching by the operator.

[0009] Furthermore, the tatami mat sewing device in Patent Document 2 changes the sewing needle height position in accordance with tatami mats of a variety of thicknesses, but it is believed that the thickness of the tatami mats to be sewn is determined by the operator measuring the tatami mat thickness. There are also devices that adjust the needle height position by inputting the tatami mat thickness value into the device or by selecting between thick and thin tatami mats, but in those cases too, the tatami mat thickness is measured and input by the operator, or the operator selects between thick and thin tatami mats by switching between them, etc.

[0010] Therefore, even in Patent Document 2, there is a risk of human error occurring when the worker inputs the tatami thickness value incorrectly or when the worker makes a switching mistake.

[0011] In view of the above-mentioned problems, the main object of the present invention is to provide a tatami mat sewing device that is capable of detecting thread breakage depending on the thickness of the tatami mat, such as thick or thin tatami mats. [Means for solving the problem]

[0012] A tatami sewing device according to one aspect of the present invention is a tatami sewing device for sewing tatami mats, and is equipped with a thread breakage detection means for detecting thread breakage in the sewing thread.The thread breakage detection means has a detection sensor for detecting the amount of thread used, and a control means, and is characterized in that the control means determines that a thread breakage has occurred when the actual amount of thread used measured by the detection sensor falls below a predetermined threshold value corresponding to the tatami mat thickness or needle height.

[0013] By configuring it in this way, it is possible to detect thread breakage according to the tatami thickness or needle height when sewing the tatami, so even if the sewing thread breaks midway through due to some kind of problem, the sewing thread becomes frayed, or the sewing thread runs out, it is possible to prevent the tatami from being sewn in the same way, which would result in a messy sewn tatami, or to prevent the stitches from being moved forward in the same way. Note that needle height refers to the height at which the needle is inserted from the bottom of the tatami, and is usually determined according to the tatami thickness, so either can be used.

[0014] Furthermore, this tatami sewing device is characterized in that the control means of the thread breakage detection means is provided with a plurality of threshold data corresponding to the tatami thickness or needle height, and selects a predetermined threshold value according to the tatami thickness or needle height of the tatami being sewn.

[0015] By configuring it in this way, it is possible to easily detect thread breakage according to the tatami thickness or needle height, such as two levels of tatami thickness, such as thin tatami and thick tatami, or multiple levels, by setting the threshold value.

[0016] The tatami sewing device further includes a tatami thickness measuring means for measuring the thickness of the tatami, and the thread breakage detection means selects a predetermined threshold value in accordance with the tatami thickness measured by the tatami thickness measuring means.

[0017] With this configuration, the tatami thickness measuring means measures the thickness of the tatami to be sewn, and thread breakage can be detected according to the tatami thickness and needle height.

[0018] In addition, this tatami mat sewing device is characterized in that the thread breakage detection means has an input means for inputting the tatami mat thickness or needle height of the tatami mat to be sewn, and selects a predetermined threshold value depending on the tatami mat thickness input.

[0019] By configuring it in this way, the operator can simply input the thickness of the tatami mat to be sewn or the needle height, and thread breakage detection can be performed according to the tatami mat thickness and needle height.

[0020] Furthermore, this Tatami mat sewing device is characterized in that the plurality of threshold data includes two threshold data corresponding to the tatami mat thickness or needle height of a thick tatami mat and a thin tatami mat.

[0021] By configuring it in this way, it is possible to easily detect yarn breakage in two stages: thick tatami mats and thin tatami mats.

[0022] Furthermore, this tatami mat sewing device is characterized in that the thread breakage detection means further has input means capable of inputting the stitching pitch when sewing, and the control means determines that a thread breakage has occurred when the actual amount of thread used measured by the detection sensor falls below a threshold value calculated based on the estimated amount of thread used, which is calculated from the tatami mat thickness or needle height and the stitching pitch when sewing.

[0023] By configuring in this way, it is possible to more accurately detect thread breakage according to not only the tatami mat thickness or needle height but also the stitch pitch.

[0024] Furthermore, this tatami sewing device is characterized in that the thread breakage detection means is such that the input means can further input stitching methods such as ladder stitching and zigzag stitching when sewing, and the threshold calculated by the control means is based on the estimated usage amount calculated from the tatami thickness or needle height and stitching method.

[0025] By configuring in this way, it is possible to more accurately detect thread breakage according to not only the tatami mat thickness or needle height but also the stitching method such as ladder stitch or zigzag stitch.

[0026] The tatami sewing device further comprises a thread holding section for holding the sewing thread to be fed out, and the thread breakage detection means has as the detection sensor a roller equipped with an encoder around which the sewing thread is wound and passes on the path from the thread holding section to the sewing needle.

[0027] With this configuration, it is possible to detect the amount of thread used by the roller equipped with an encoder through which the sewing thread passes in the sewing device.

[0028] In addition, this tatami sewing device is characterized in that the control means calculates the actual amount of thread used by multiplying the number of rotations of the encoder by the amount of sewing thread fed out per one rotation of the encoder.

[0029] With this configuration, it is possible to easily detect the amount of yarn used. That is, the amount of yarn used can be detected based on the number of rotations of the roller equipped with the encoder.

[0030] In addition, this tatami mat sewing device is characterized in that the control means calculates the actual amount of thread used as the amount of sewing thread fed out from the number of rotations of the encoder when the sewing needle makes one round trip, and calculates a threshold value from the estimated amount of thread used corresponding to one round trip of the sewing needle.

[0031] By configuring it in this manner, the amount of yarn usage can be converted into the number of rotations of the roller equipped with the encoder, making it easy to calculate the threshold value for the estimated amount of yarn usage and preventing a discrepancy between the actual amount of yarn usage and the estimated amount of yarn usage.

[0032] Furthermore, this tatami sewing device is characterized in that the encoder is provided on the path from the thread holding unit to the sewing needle, closer to the sewing needle than a tension member that applies tension to the sewing thread, and in the vicinity of the tension member.

[0033] By configuring it in this way, the roller equipped with the encoder is located closer to the sewing needle than the tension member that applies tension to the sewing thread, and in the vicinity of the tension member, i.e., by locating it in a location where the thread is less likely to loosen, it becomes possible to accurately detect the amount of thread used.

[0034] The tatami mat sewing device is also characterized in that it includes two tension members, and the encoder is disposed between the two tension members on the path from the thread holding unit to the sewing needle.

[0035] With this configuration, the roller equipped with the encoder is disposed between the two tension members, which makes it difficult for the twisted yarn to become loose, and enables more accurate detection of the amount of yarn used.

[0036] In addition, this tatami sewing device further comprises a sewing machine rotation detection plate that is linked to the operation of the sewing needle, and a needle position detection sensor, and when the sewing needle is in a predetermined position, the needle position detection sensor detects the sewing machine rotation detection plate.

[0037] This configuration makes it possible to detect needle movement and detect thread breakage according to needle movement. For example, if thread breakage is detected when the sewing machine needle is inserted into the tatami mat, it would be cumbersome to change the thread, but by detecting thread breakage when the needle is away from the tatami mat, it becomes easier to change the thread.

[0038] Furthermore, this Tatami sewing device is characterized in that it calculates the actual amount of thread used from the number of rotations of the encoder during the interval from when the needle position detection sensor detects the position of the sewing needle to when it next detects it, and determines whether thread has broken by comparing the actual amount of thread used with the threshold value corresponding to that interval.

[0039] By configuring it in this way, the movement of the needle once around the tatami mat, for example, when the thread comes out of the tatami mat, is used as the reference, and the reference section is the one revolution from when the thread is inserted into the tatami mat until it returns to its original state with the thread out of the tatami mat, and the amount of thread used can be determined from the number of rotations of the roller equipped with the encoder at this time.

[0040] In addition, this tatami sewing device is characterized in that the needle position detection sensor detects when the tip of the sewing needle is at the position farthest from the side of the tatami, and each time the needle position detection sensor detects the position of the sewing needle, it performs the thread breakage determination, records data based on the encoder, and resets it.

[0041] By configuring in this way, it becomes possible to determine the amount of thread used for each complete rotation of the needle.

[0042] In addition, this tatami sewing device is characterized in that the tatami thickness measuring means has a tatami presser foot that moves up and down and a lifting means for lifting the tatami presser foot, and measures the thickness of the tatami using the distance that the tatami presser foot moves.

[0043] This configuration allows the thickness of the tatami to be measured mechanically without manual intervention, preventing human error and enabling accurate and easy measurement of the tatami thickness, and enabling thread breakage detection according to the measured tatami thickness or needle height. It also enables sewing with an appropriate needle height and stitch depth for a good finish.

[0044] Furthermore, this tatami sewing device is characterized in that the tatami thickness measuring means is a means for measuring the thickness of a tatami by using the distance between the bottom of the tatami and the upper limit position of the tatami presser in a standby state as a reference distance, and subtracting from this reference distance the distance traveled by the tatami presser until it comes into contact with the surface of the tatami and stops.

[0045] By configuring it in this way, when actually measuring the thickness of a tatami mat, it is necessary to add a separate, independent measuring means, but it is possible to measure the thickness of the tatami mat using only the reference distance and the movement distance of the tatami mat presser, which reduces interference with the sewing mechanism and also saves space in the machine.

[0046] Furthermore, this tatami sewing device is characterized in that the lifting means has a drive means connected to the tatami presser foot, a connection means connecting the drive means to the tatami presser foot, and an encoder attached to the connection means, and measures the thickness of the tatami by measuring the distance the tatami presser foot moves using the encoder.

[0047] By configuring it in this way, it is possible to measure the travel distance and the thickness of the tatami mat simply by attaching an encoder to the connection means that connects the tatami presser foot and drive means that are normally provided on tatami mat sewing devices.As there is no need to provide a separate complex mechanism, this is ideal as it does not interfere with sewing and also helps to save space in the device.

[0048] Furthermore, this tatami sewing device is characterized in that the connection means has a link mechanism and / or cam mechanism, the encoder is attached to the link mechanism or the cam mechanism, and the encoder converts the amount of rotation of the link or cam that constitutes the link mechanism or the cam mechanism into a vertical distance, which is used as the movement distance of the tatami presser, thereby measuring the thickness of the tatami.

[0049] By configuring it in this way, simply by attaching an encoder to the link mechanism and / or cam mechanism, which are the connection means, it is possible to measure the travel distance and the tatami thickness, which is ideal as it does not interfere with sewing and also allows the device to be more space-saving.

[0050] Furthermore, this tatami sewing device is a tatami sewing device for performing backstitches or frame stitches on the side edges of tatami mats and sewing the edges of the tatami mats to the side edges of the tatami mats, and is equipped with a sewing mechanism to which a sewing needle having a hole for inserting an upper thread is attached and which sews the tatami mat by swinging the sewing needle, and a lifting mechanism to raise and lower the position of the sewing needle, the lifting mechanism having a motor for the lifting mechanism that drives the lifting mechanism, the sewing mechanism having a sewing machine pivot shaft that serves as the pivot shaft of the sewing mechanism, a sewing needle drive shaft that drives the sewing needle, and a sewing mechanism motor that drives the sewing needle, and is characterized in that the height and depth of sewing by the sewing needle can be adjusted simultaneously based on the rotation of the motor for the lifting mechanism.

[0051] This configuration allows the sewing needle to be adjusted to the appropriate height and depth, enabling good backstitching even when the thickness of the tatami varies. It also eliminates the need for tedious manual work by the worker, improving work efficiency.

[0052] The tatami mat sewing device is also characterized in that the sewing machine pivot shaft of the sewing mechanism and the sewing needle drive shaft are the same shaft.

[0053] With this configuration, the sewing machine pivot shaft and the sewing needle drive shaft are configured as a single shaft, which reduces the number of parts, simplifies the structure, and enables space saving.

[0054] In addition, in this Tatami mat sewing device, the sewing mechanism has a needle swing shaft about which the needle swings, and a connecting member and / or a cam that connects the needle drive shaft and the swing shaft.

[0055] With this configuration, the sewing needle can be driven and swung by the sewing mechanism motor via the needle drive shaft, connecting member, cam, and swing shaft.

[0056] In addition, this tatami mat sewing device is characterized in that the sewing mechanism has a hook that houses a bobbin around which a lower thread is wound and is rotated in conjunction with the drive of the sewing needle, and the hook rotation drive shaft that rotates the hook is coaxial with the sewing needle drive shaft.

[0057] By configuring it in this way, one motor can drive the sewing needle and rotate the hook simultaneously, and by configuring the hook rotation drive shaft and the sewing needle drive shaft to be on the same shaft, it becomes easier to synchronize operations and it becomes possible to save space in the device.

[0058] In addition, this Tatami mat sewing device is characterized in that the rotary drive shaft for the hook is the same as the pivot shaft for the sewing machine and the drive shaft for the sewing needle.

[0059] With this configuration, the rotary shaft for the hook, the pivot shaft for the sewing machine, and the drive shaft for the needle are all coaxial, which further reduces the space required for the device.

[0060] Furthermore, this tatami mat sewing device is characterized in that the sewing mechanism has a thread take-up lever for pulling up the upper thread, the thread take-up lever is located near the end opposite to the end where the sewing needle is located, and the thread take-up drive shaft for driving the thread take-up lever is on the same axis as the sewing machine pivot shaft.

[0061] With this configuration, the drive shaft of the thread take-up lever is configured to be the same as the rotating shaft of the sewing machine, thereby making it possible to save space in the device.

[0062] The tatami mat sewing device is also characterized in that the thread take-up drive shaft is the same as the sewing machine pivot shaft and the sewing needle drive shaft.

[0063] With this configuration, the thread take-up drive shaft, the sewing machine pivot shaft, and the sewing needle drive shaft are configured as a single shaft, thereby making it possible to further reduce the space required for the device.

[0064] The tatami mat sewing device also has a hook that houses a bobbin around which a lower thread is wound and that is driven to rotate in conjunction with the driving of the sewing needle, and the hook rotation drive shaft that drives the hook to rotate is the same shaft as the sewing machine pivot shaft, the sewing needle drive shaft, and the thread take-up drive shaft.

[0065] By configuring it in this way, the four shafts - the sewing machine pivot shaft, the needle drive shaft, the hook rotation drive shaft and the thread take-up drive shaft - are all configured as a single shaft, which makes it possible to significantly reduce the space required for the entire device.

[0066] Furthermore, this tatami mat sewing device is characterized in that a sewing mechanism motor is disposed at the end of the sewing mechanism, the sewing mechanism motor and the sewing machine pivot shaft are connected by a sprocket or a belt, the sewing mechanism motor, the sewing machine pivot shaft, the sewing needle drive shaft and the sewing needle swing shaft are fixed in position, and the sewing mechanism motor rises and falls in accordance with the rise and fall of the position of the sewing needle.

[0067] By configuring it in this way, the arrangement of the sewing mechanism motor, sewing machine pivot shaft, sewing needle drive shaft and sewing needle swing shaft is fixed, and the sewing mechanism motor rises and falls in accordance with the rise and fall of the sewing needle.Therefore, even if the sewing machine pivot shaft and the sewing needle drive shaft are the same shaft, the sewing mechanism motor moves in conjunction with the entire sewing machine, preventing the sewing needle from moving.

[0068] In other words, if the motor were fixed, the sewing needle would move as the sprocket or belt rotated, but since the motor is not fixed and rises and falls in sync with it, the height and depth can be changed simultaneously in accordance with the thickness of the tatami mat with one operation, and because the sewing needle does not move, precise adjustments can be made when adjusting the height and depth of the sewing needle.

[0069] The tatami mat sewing device is also characterized in that the sewing machine pivot shaft is provided near the center of the sewing mechanism.

[0070] With this configuration, the stitch depth can be adjusted by adjusting the stitch height appropriately according to the thickness of the tatami mat. This eliminates the need for the operator to perform two steps of adjusting the stitch depth in addition to the height, improving the operator's work efficiency. This allows the operator to perform backstitches with a good finish at the appropriate stitch height and stitch depth even if the thickness of the tatami mat changes.

[0071] Furthermore, this tatami mat sewing device is characterized in that the sewing needle is arranged on one end side of the sewing machine pivot shaft of the sewing mechanism, and the take-up lever is arranged on the other end side of the sewing machine pivot shaft of the sewing mechanism.

[0072] By configuring it in this way, even when the sewing device is moved around the sewing machine pivot shaft according to the thickness of the tatami mat, the relative positions of the thread take-up lever and the sewing needle remain fixed, and the sewing machine pivot shaft, the needle drive shaft and the thread take-up lever drive shaft are all on the same axis. Therefore, even if the thickness of the tatami mat changes, the thread take-up lever and the sewing needle always operate in sync, allowing for stable sewing.

[0073] Furthermore, this Tatami mat sewing device is characterized in that the motor for the lifting mechanism is a servo motor.

[0074] With this configuration, the servo motor can be controlled to drive the actuator back and forth quickly and accurately.

[0075] In addition, this tatami sewing device further comprises a tatami thickness measuring means capable of measuring the thickness of the tatami, and the tatami thickness measuring means has a tatami presser foot that moves up and down and a lifting means for lifting the tatami presser foot, and is characterized in that the thickness of the tatami is measured using the distance that the tatami presser foot moves.

[0076] By configuring it in this way, the thickness of the tatami mat can be measured accurately and easily, so that backstitching can be performed with an appropriate stitch height and stitch depth for a good finish.

[0077] In addition, this tatami sewing device has a tatami thickness measuring means that uses the distance between the bottom of the tatami and the upper limit position of the tatami presser in a standby state as a reference distance, and measures the thickness of the tatami by subtracting from this reference distance the distance traveled by the tatami presser until it comes into contact with the surface of the tatami and stops.

[0078] By configuring it in this way, when actually measuring the thickness of a tatami mat, it is necessary to add an independent measuring means separately, but by measuring the thickness of the tatami mat using the reference distance and the movement distance of the tatami mat presser, there is no interference when sewing, which is preferable.

[0079] Furthermore, this tatami sewing device is characterized in that the lifting means has a drive means and link mechanism connected to the presser foot, and an encoder attached to the link mechanism, and the thickness of the tatami is measured by converting the amount of rotation of the links that make up the link mechanism into a vertical distance using the encoder, which is used as the movement distance of the tatami presser foot.

[0080] By configuring it in this way, simply by attaching an encoder to the link mechanism, it is possible to measure the travel distance and the tatami thickness, which is advantageous as it does not interfere with sewing.

[0081] This tatami sewing device is also characterized by having a control means for controlling the motor for the lifting mechanism based on the thickness of the tatami measured by the tatami thickness measuring means, thereby adjusting the height and depth of the sewing by the sewing needle.

[0082] By configuring it in this way, it is possible to reliably sew according to the thickness of the tatami, and it is possible to prevent the sewing needle from interfering with other parts and breaking, or from sewing in a position that cannot be sewn, or to prevent the stitches from being messy.

[0083] This tatami sewing device is also characterized by having a determination means for determining whether the height and depth positions of the sewing needles are within the appropriate sewing position range based on the thickness of the tatami measured by the tatami thickness measurement means, and a malfunction prevention means for preventing malfunctions if the position is not within the appropriate sewing position range.

[0084] Here, malfunction prevention means includes, for example, stopping sewing (not starting sewing) or giving a notification using a warning light, etc. By configuring in this way, if the sewing needle is not positioned within the allowable range in the height direction and depth direction of sewing, it is possible to prevent the sewing machine from malfunctioning due to the needle interfering with other parts and breaking, or being unable to sew the tatami mat edge.

[0085] Furthermore, by providing this malfunction prevention means, when it is desired to adjust the stitch height and stitch depth beyond the initial range set for ordinary tatami mats, or when using special tatami mats that are different in thickness or size from ordinary tatami mats, sewing can be prevented from starting or a warning can be issued if the sewing needle is not positioned within the allowable range in the height and depth directions. This makes it possible to prevent interference and breakage of the sewing needle, as well as malfunction of the sewing machine, even in the case of special tatami mats. [Effects of the Invention]

[0086] According to the present invention, thread breakage can be detected when sewing tatami mats depending on the thickness of the tatami mats and the needle height. Therefore, even if the sewing thread breaks midway due to some kind of trouble, the sewing thread becomes frayed, or the sewing thread runs out, it is possible to prevent the tatami mat from being sewn as is, which could result in messy stitching, or the stitches being moved forward as is, resulting in unsewn areas and a poor finish. [Brief explanation of the drawings]

[0087] [Figure 1] 1 is a plan view showing a schematic configuration of a tatami mat sewing device according to an embodiment of the present invention. [Figure 2] 1 is a side view showing a schematic configuration of a tatami mat sewing device according to an embodiment of the present invention. [Figure 3]FIG. 2 is a front view of the sewing machine body according to the embodiment. [Figure 4] FIG. 2 is a side view of the sewing machine body of the present embodiment with the needle in the upper position. [Figure 5] FIG. 2 is a side view of the sewing machine body of the present embodiment with the needle in the lower position. [Figure 6] FIG. 2 is a plan view of the sewing machine body of the present embodiment. [Figure 7] 10A and 10B are explanatory diagrams illustrating adjustment of the position of the sewing needle in the sewing machine body in the height direction and depth direction of sewing according to the present embodiment. [Figure 8] FIG. 2 is a side view showing the configuration of the tatami mat thickness measuring means of the present embodiment. [Figure 9] FIG. 2 is a front view showing the configuration of the tatami mat thickness measuring means of the present embodiment. [Figure 10] FIG. 2 is a schematic side view showing a configuration including a yarn breakage detection means according to the present embodiment. [Figure 11] 11 is a schematic side view showing the internal structure of FIG. 10 with some members removed. [Figure 12] FIG. 4 is a partially enlarged perspective view showing the configuration of a yarn breakage detecting means. [Figure 13] FIG. 2 is an enlarged cross-sectional view of the tip of the sewing needle. [Figure 14] FIG. 10 is a diagram showing a sewing machine rotation detection plate that detects the movement of a sewing needle. [Figure 15] 10 is a graph showing threshold values ​​for determining thread breakage according to thick tatami matting and thin tatami matting. [Figure 16] FIG. 10 is a diagram showing an example of a sewing method. [Figure 17] 10A and 10B are diagrams showing needle height and stitch pitch in zigzag stitch and ladder stitch. [Figure 18] 10 is a graph showing the threshold value for determining thread breakage according to the tatami thickness (thick tatami and thin tatami), stitching method, and stitching pitch. [Figure 19] 10 is a graph showing a threshold value for determining thread breakage according to an arbitrary tatami thickness, stitching method, and stitching pitch. DETAILED DESCRIPTION OF THE INVENTION

[0088] A tatami mat sewing device according to one embodiment of the present invention will be described in detail below. However, the present invention is not limited to this embodiment. Furthermore, the components in the following embodiment include those that are easily replaceable by those skilled in the art, or those that are substantially identical. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made without departing from the spirit of the present invention.

[0089] (1. Overall configuration of the tatami mat sewing device) FIG. 1 is a plan view showing the schematic configuration of a tatami mat sewing device according to this embodiment, and FIG. 2 is a side view showing the schematic configuration of the same sewing device.

[0090] In the tatami mat sewing device of this embodiment, the side 110 of the tatami mat 100 refers to the longitudinal side of the tatami mat 100 if the tatami mat 100 is for a full tatami mat, and to the side perpendicular or approximately perpendicular to the side on the frame side if the tatami mat is for a half tatami mat. Also, the left-right direction (longitudinal direction of the tatami mat) in Figure 1 is designated as direction A, the up-down direction (transverse direction of the tatami mat) is designated as direction B, and the up-down direction (thickness direction of the tatami mat) in Figure 2 is designated as direction C.

[0091] As shown in Figures 1 and 2, the tatami mat sewing device 1 of this embodiment is a device for sewing tatami mat edges, and is primarily comprised of a sewing machine body 10, a table 11 on which a tatami mat 100 is placed, and a frame 12. The table 11 also has a central base extending in the direction A in Figure 1, with multiple rollers 11A attached to the left and right of the central base at predetermined intervals in the A direction. This makes it possible to transport the placed tatami mat 100 along the A direction.

[0092] 1 is the longitudinal direction of the tatami mat 100, and with the tatami mat 100 placed on the table 11, the sewing machine body 10 backstitches the side edges 110 of the tatami mat 100 while feeding the tatami mat 100 in the A direction, and the tatami mat edge is sewn to the side edges 110 of the tatami mat 100.

[0093] (2. Structure of the sewing machine body) Next, we will explain the sewing machine body 10, which is the main component of the Tatami sewing device of this embodiment. Figure 3 is a front view of the sewing machine body part of the sewing device of this embodiment, Figure 4 is a side view of the sewing machine body part with the sewing needle in the upper position, Figure 5 is a side view of the sewing machine body part with the sewing needle in the lower position, Figure 6 is a plan view of the sewing machine body part, and Figure 7 is an explanatory diagram for explaining the position adjustment of the sewing needle of the sewing machine body part in the height direction and depth direction of sewing.

[0094] As shown in FIGS. 3 to 6, the sewing machine body 10 includes a sewing mechanism 20, a lifting mechanism 30, and a motor 40 for the lifting mechanism as main components.

[0095] The sewing mechanism 20 is a mechanism for sewing the edges of the tatami mat to the side edges 110 of the tatami mat 100. The sewing mechanism 20 receives a driving force from a sewing mechanism motor 25 and swings to perform the sewing operation.

[0096] The sewing mechanism 20 includes a sewing machine arm 21, a needle arm 22, a cam 23, a connecting member 24, a sewing mechanism motor 25, and a hook 26.

[0097] The sewing machine arm 21 is provided so as to be able to swing about a sewing machine pivot shaft 211, which is the pivot shaft of the sewing mechanism 20. By swinging the sewing machine arm 21, the height and depth position of the sewing needle 112 relative to the tatami mat 100 can be changed.

[0098] A handle shaft 51 is provided penetrating the sewing machine arm 21, and a circular handle 50 is attached to one end thereof. The handle 50 is provided for cases where, when the sewing machine stops due to an overload or the like, such as when a foreign object gets caught during sewing operation, it is easier to control whether to rotate the handle 50 forward or backward to remove the foreign object by manually turning the handle 50 with an analog operation rather than by a motor, thereby moving the needle blade. Rotation of the handle shaft 51 rotates the sewing machine arm 21 as a unit. In other words, the handle shaft 51 serves as the sewing machine pivot axis 211.

[0099] The sewing machine pivot shaft 211 is located near the center of the sewing mechanism 20. This allows the stitch height to be adjusted appropriately in accordance with the thickness of the tatami mat with one operation, and the stitch depth can also be adjusted. In other words, as shown in Figures 7(a) and 7(b), the position of the sewing needle swing shaft 221, which is the center of rotation of the needle arm 22 to which the arc-shaped sewing needle 112 is attached, can be adjusted from sewing position (X1, Y1) for thick tatami mats to sewing position (X2, Y2) for thin tatami mats, eliminating the need for two-stage position adjustment by moving the sewing machine in δX and δY directions.

[0100] Needle arm 22 is provided on the upper part of sewing machine arm 21 so as to be able to swing about needle swing shaft 221. An arc-shaped sewing needle 112 is attached to the tip of needle arm 22. A sewing thread called an upper thread is threaded through needle 112.

[0101] The cam 23 rotates upon receiving power from the sewing mechanism motor 25, causing the needle arm 22 to swing. Furthermore, because the outer periphery of the cam 23 is uneven, a guide roller 71 rotates along the outer periphery of the cam 23, physically determining the amount of thread tension that the thread take-up 70 pulls. The rotational force of the sewing mechanism motor 25 is transmitted to the sprocket 52 and handle shaft 51 via the sprocket 252 and chain 60, and is then transmitted to the cam 23 by the rotation of the handle shaft 51.

[0102] One end of the connecting member 24 is rotatably connected to the cam 23, and the other end is rotatably connected to the needle swing shaft 221. The connecting member 24 swings the needle arm 22 around the needle swing shaft 221 as the cam 23 rotates.

[0103] The rotation of the handle shaft 51 is transmitted to the needle swing shaft 221 via the connecting member 24, causing the needle swing shaft 221 to rotate and swing the needle arm 22. In other words, the handle shaft 51 serves as the needle drive shaft 113.

[0104] Therefore, the sewing machine pivot shaft 211 and the sewing needle drive shaft 113 are coaxial, which makes it possible to reduce the number of parts and simplify the structure.

[0105] The sewing mechanism motor 25 is disposed at the end of the sewing mechanism 20. The sewing mechanism motor 25, the sewing machine pivot shaft 211, the sewing needle drive shaft 113 and the sewing needle swing shaft 221 are fixedly arranged, and the sewing mechanism motor 25 is raised and lowered according to the position of the sewing needle 112. As a result, even if the sewing machine pivot shaft 211 and the sewing needle drive shaft 113 are the same shaft, the sewing mechanism motor 25 moves in conjunction with the entire sewing machine, preventing the sewing needle 112 from moving.

[0106] A chain 60 is hung between a sprocket 252 attached to a rotary shaft 251 of the sewing mechanism motor 25 and a sprocket 52 attached to the handle shaft 51. The rotation of the sewing mechanism motor 25 is transmitted to the handle shaft 51 via the chain 60.

[0107] The hook 26 houses a bobbin around which a sewing thread is wound, and is rotated in conjunction with the drive of the sewing needle 112. The hook 26 is attached to the tip of the sewing machine arm 21, and rotates synchronously with the needle arm 22 to perform sewing operations. As the sewing machine arm 21 swings around the sewing machine pivot shaft 211 as a fulcrum, the hook 26 and the needle arm 22 move up and down, changing the height and depth of sewing by the sewing needle 112.

[0108] The hook 26 is attached to the tip of the sewing machine arm 21, and the central axis of the hook 26 and the sewing mechanism motor 25 forms the sewing machine rotation axis 211, so that the operation of the sewing mechanism 20 is stable.

[0109] The rotational force of the sewing mechanism motor 25 is transmitted to the handle shaft 51 via the sprocket 252 and the chain 60. When the handle shaft 51 rotates, the bevel gear 263 attached to the handle shaft 51 rotates, and the power is transmitted to the hook shaft 261, and then to the hook 26 via the hook shaft 261. In other words, the handle shaft 51 serves as the hook rotation drive shaft 262, and the hook rotation drive shaft 262 is coaxial with the sewing machine turning shaft 211 and the needle drive shaft 113.

[0110] The lifting mechanism 30 is driven based on the rotation of the lifting mechanism motor 40. As shown in Figures 4 and 5, the lifting mechanism 30 applies a moving force in the up and down direction (direction C) to the sewing mechanism 20 by rotating the lifting mechanism motor 40, and by swinging the sewing mechanism 20, changes the position of the sewing needle 112 in the height and depth directions relative to the tatami mat 100. Note that Figure 4 shows the state when it has moved upward, and Figure 5 shows the state when it has moved downward.

[0111] In addition, in this embodiment, as an example, the lifting mechanism 30 is configured to allow movement within a sewing height range of 7 mm to 38 mm, with a sewing depth of 30 mm when the sewing height is 7 mm, and a sewing depth of 45 mm or more when the sewing height is 38 mm. This configuration allows for reliable backstitching and other operations on tatami mats of various thicknesses, from thin to thick. The above-described range of movement for the sewing height and depth is merely an example, and is not limited thereto. It is also possible to configure the sewing height to a range of 5 mm to 40 mm, with a sewing depth of 20 mm or more when the sewing height is 5 mm, and a sewing depth of 45 mm or more when the sewing height is 40 mm, for example.

[0112] The lifting mechanism motor 40 is configured as a servo motor that can be feedback controlled, and therefore can be driven accurately and quickly.

[0113] The servo motor may be any of various servo motors that can be feedback controlled, such as a DC servo motor, an AC servo motor, or a pulse motor equipped with an encoder means that can output a rotation phase angle signal.

[0114] The lifting mechanism 30 is composed of multiple links. Specifically, a base end of a first link 31 is connected to a lifting mechanism motor shaft 41 so as to rotate integrally therewith. One end of a second link 32 is rotatably connected to one end of the first link 31, and the other end of the second link 32 is rotatably connected to one end of a third link 33.

[0115] The other end of the third link 33 is connected to the sewing machine arm 21. The third link 33 is connected to the sewing machine arm 21 near the needle swing shaft 221.

[0116] The thread take-up 70 moves up and down the upper thread supplied from a thread supply source to the sewing needle 112. The thread take-up 70 moves up and down during sewing to pull up the upper thread. The thread is passed through the eye of the sewing needle 112, enabling sewing. The thread take-up 70 is located near the end opposite to the end where the sewing needle 112 is located, and a thread take-up drive shaft 701 that drives the thread take-up 70 is coaxial with the sewing machine pivot shaft 211. In other words, the thread take-up drive shaft 701 is coaxial with the sewing machine pivot shaft 211 and the needle drive shaft 113.

[0117] (3. Configuration of tatami thickness measuring means) 8 is a side view showing the configuration of the tatami thickness measuring means of this embodiment, and Fig. 9 is a front view showing the configuration of the same tatami thickness measuring means. As shown in Figs. 8 and 9, the tatami thickness measuring means 80 is equipped with a tatami presser 81 that moves up and down, pressing against the top surface of the tatami 100 to secure it in place. The tatami presser 81 is designed to be able to move up and down between a sewing position shown by the solid lines in Figs. 4 and 5, and a retracted / standby position shown by the dotted lines.

[0118] The tatami thickness measuring means 80 mainly comprises a tatami mat presser 81, a link mechanism 82, and an air cylinder 83. As the air cylinder 83 expands and contracts, the tatami mat presser 81 moves up and down in a circular motion via the link mechanism 82. An encoder 84 is attached to the link mechanism 82. The encoder 84 converts the amount of rotation of the links of the link mechanism 82 into a distance in the height direction. Note that the air cylinder 83 is one example of this embodiment, and an electric cylinder or the like may also be used.

[0119] The tatami mat presser 81 mainly comprises a support member 81A, four pulleys 81B rotatably attached to the support member 81A, and a belt 81C. The pulleys 81B are attached to both the left and right sides at a predetermined distance in the front-to-rear direction, and a belt 81C is attached to each pair of pulleys 81B on the left and right.

[0120] As a result, even when the tatami mat 100 is pressed from the surface by the tatami mat holder 81, the tatami mat 100 is not damaged by the belt 81C, and the tatami mat 100 can slide in the direction A while being held between the tatami mat 100 and the base 11 on which the lower roller 11A is arranged.

[0121] An air cylinder 83 and a link mechanism 82 are rotatably connected to the support member 81A, thereby allowing the support member 81A to rotate. The air cylinder 83 is connected near the center of the support member 81A, and two links 82 are connected to the front and two to the rear. An encoder 84 is attached to the rotation axis of one of these links 82.

[0122] With this configuration, the measurement of tatami thickness by the tatami thickness measuring means 80 in this embodiment is fixed at the reference distance, which is the distance between the bottom of the tatami mat during sewing and the bottom of the tatami presser foot 81 which is retracted upward and in a standby state. Then, at the start of sewing the tatami mat, when the tatami presser foot 81 moves to a position where it abuts against the surface of the tatami mat, the encoder 84 converts the amount of rotation of the link of the link mechanism 82 into the distance traveled in the height direction, and the tatami thickness is measured by subtracting this distance from the reference distance.

[0123] It is also possible to measure the tatami thickness without using the reference distance described above, by setting the point when the bottom of the tatami presser foot 81 reaches the bottom of the tatami as the origin of the travel distance, and measuring the tatami thickness as the value measured when the tatami presser foot 81 is in contact with the surface of the tatami. There are also various other possible methods, such as measuring with a photoelectric sensor that detects distance by the amount of light reflected from the top to the bottom of the tatami, measuring from the side of the tatami, or attaching a slit and photomicrosensor to the tatami presser foot 81, but the above configuration is preferable because it does not interfere with sewing.

[0124] The tatami mat sewing device 1 also includes control means for adjusting the height and depth of stitching by the sewing needles. This control means is realized by a computer made up of components such as an I / O, CPU, ROM, RAM, SDD, and peripheral circuits (not shown). This computer is mounted inside the operation panel 85 shown in Figure 9, and the sewing machine main body 10, tatami mat thickness measuring means 80, etc. are connected to this computer by cables.

[0125] The computer need not be located inside the operation panel 85 but may be located in another location, and the number of computers is not limited to one but may be multiple computers located in various locations.

[0126] This computerized control means controls the height and depth of sewing by the sewing needle 112. The computer also measures the thickness of the tatami mat 100 using the tatami mat thickness measuring means 80.

[0127] Specifically, the operation of the motor 40 for the lifting mechanism is controlled based on the tatami thickness measured by the measurement method of the tatami thickness measuring means 80 described above, and the height and depth of the sewing by the sewing needle 112 is adjusted in accordance with the tatami thickness.

[0128] This allows the tatami mat 100 to be sewn securely in accordance with its thickness, preventing the needle from interfering with other parts and breaking, preventing sewing from being performed in a position that cannot be sewn, and resulting in messy stitches.

[0129] The Tatami mat sewing device 1 of this embodiment also includes a determination means for determining whether the position of the sewing needle 112 is within an appropriate sewing position range, and a malfunction prevention means for preventing malfunctions when the needle 112 is not within the appropriate sewing position range. These determination means and malfunction prevention means are also realized by the computer described above.

[0130] This determination means determines whether the position of the sewing needle 112 in the sewing height direction and depth direction is within the appropriate sewing position range, based on the thickness of the tatami mat measured by the tatami mat thickness measurement means 80. If it is determined that the sewing needle 112 is not within the appropriate sewing position range, a warning is displayed on the display of the operation panel, and the warning light 86 at the top of the operation panel flashes.

[0131] This prevents the sewing needle 112 from interfering with other parts and breaking when the position of the sewing needle 112 in the height direction and depth direction is not within the allowable range, preventing the sewing machine from breaking due to the inability to sew the tatami mat edge, and preventing the stitches from looking messy even if sewing is possible.

[0132] When the warning light 86 flashes, the operator adjusts the position of the needle 112 by moving it to an appropriate position manually or by operating the control panel.

[0133] (4. Configuration of yarn breakage detection means) Fig. 10 is a schematic side view showing a configuration including the thread breakage detection means of this embodiment. Fig. 11 is a schematic side view showing the internal structure with some components removed. Fig. 12 is a partially enlarged perspective view showing the configuration of the thread breakage detection means. Fig. 13 is an enlarged cross-sectional view showing the tip of the sewing needle.

[0134] As shown in Figures 10, 11 and 12, the tatami mat sewing device 1 is equipped with thread holding means for holding a roll 91 of thread 90 used to sew the tatami mats together. The thread 90 is wound from the roll 91 held by the thread holding means through a thread hook 92, around a tension roller 93, an encoder roller 94 equipped with an encoder, and a tension roller 95, in that order, before passing through a thread path 96, a thread take-up 70, another thread path 96, and a slack eliminating section 97, in that order, before being hung on a sewing needle 112.

[0135] In addition, since the encoder roller 94 equipped with an encoder is disposed between the tension roller 93 and the tension roller 95, the yarn 90 does not become loose before or after the encoder roller 94, and the number of rotations and the amount of yarn used can be detected with high accuracy.

[0136] 13, the sewing needle 112 has a through hole 112a through which the thread 90 is inserted, and a guide groove 112b that extends from the through hole 112a in the axial direction from the sewing needle 112 and guides the thread 90 in the axial direction. As a result, the thread 90 is passed through the through hole 112a of the sewing needle 112 and arranged so as to be aligned with the guide groove 112b in the axial direction, and the thread 90 is supplied in conjunction with the movement of the sewing needle 112.

[0137] The thread 90 that is threaded on the sewing needle 112 serves as the upper thread. On the other hand, the lower thread is wound around a bobbin (not shown) in the hook 26 of the sewing mechanism 20.

[0138] Then, in conjunction with the swinging of the needle arm 22, the sewing needle 112 pierces and penetrates the side of the tatami mat 100, enters the bobbin of the hook 26, is pulled out from the bobbin, and performs a reciprocating arc motion in which the sewing needle 112 is pulled out from the side of the tatami mat 100.

[0139] Furthermore, as the sewing needle 112 is pulled out from the bobbin, the lower thread is pulled up and the upper and lower threads are used to sew the sides of the tatami mat 100. At this time, the tatami mat 100 is transported in the direction A in Figure 1, and the sides are sewn together in order.

[0140] 11, when the sewing needle 112 uses the thread 90, the thread 90 is supplied as needed from the raw roll 91 held by the thread holding means through the above-mentioned path. When the thread 90 passes the encoder roller 94, the encoder roller 94 rotates, and the amount of thread 90 used is calculated.

[0141] The encoder-equipped roller 94 is connected to a control means. Specifically, the encoder-equipped roller 94 is connected to an operation panel 85 shown in Fig. 9, and the operation panel 85 has a computer mounted therein that is made up of components such as an I / O, a CPU, a ROM, a RAM, an SSD, and peripheral circuits (not shown), and this computer functions as the control means.

[0142] Meanwhile, a sewing machine rotation detection plate is attached to a portion that is linked to the reciprocating arc motion of the sewing needle 112. In this embodiment, a sewing machine rotation detection plate 264 is attached to the bevel gear 263 (see FIG. 6).

[0143] As shown in Figures 14(a) and (b), the sewing machine rotation detection plate 264 is approximately circular, with a portion of the disk extending radially, and a fan-shaped portion 264a extending from the outer periphery of the disk.

[0144] A needle position detection sensor 265 is attached to the back of the sewing machine rotation detection plate 264, and when the sewing machine rotation detection plate 264 rotates in conjunction with the reciprocating arc motion of the sewing needle 112, the needle position detection sensor 265 detects the start and end positions of the fan-shaped portion 264a, thereby detecting one revolution (one reciprocating arc motion) of the sewing needle 112.

[0145] Furthermore, the needle position detection sensor 265 is connected to the operation panel 85 shown in FIG. 9, and the operation panel 85 is equipped with a computer comprised of components such as an I / O, a CPU, a ROM, a RAM, an SDD, and peripheral circuits (not shown), and this computer functions as a control means.

[0146] In this way, the control panel 85 equipped with a computer is connected to the encoder roller 94 and the needle position detection sensor 265, and information on the reciprocating movement of the sewing needle 112 by the needle position detection sensor 265 and the number of rotations of the encoder roller 94 is stored in the control means of the control panel 85, and thread breakage detection is performed based on this information.

[0147] (5-1. Method 1 for detecting thread breakage (two-stage tatami thickness)) Next, we will explain the control method for detecting thread breakage using the thread breakage detection means. As mentioned above, the tatami thickness measuring means 80 that measures the tatami thickness, the encoder roller 94 that detects the amount of thread 90 used, and the needle position detection sensor 265 that detects the movement of the sewing needle 112 are connected to the operation panel 85 equipped with a computer.

[0148] (1) For example, a criterion value for distinguishing between thick and thin tatami mats is stored in advance in the SSD (storage device) of the computer of the operation panel 85. There are various thicknesses of tatami mats, from extremely thin tatami mats such as 12 mm, to medium-thick tatami mats such as 30 mm, to standard thick tatami mats such as 50 mm, and the criterion value for tatami thickness is set to, for example, 25 mm.

[0149] The actual tatami thickness measured by the tatami thickness measuring means 80 is then sent to the computer on the operation panel 85 and saved in the SSD. The actual tatami thickness value and the judgment reference value are extracted, and the CPU compares these to determine whether the tatami is thick or thin.

[0150] (2) The SSD of the computer of the operation panel 85 also stores a threshold value for the number of revolutions of the encoder roller 94, calculated based on the estimated number of revolutions of the encoder roller 94 corresponding to the estimated amount of thread used in one reciprocating motion of the sewing needle 112 for thick and thin tatami mats. This threshold value for the number of revolutions is set lower than the estimated number of revolutions. This is because if the estimated number of revolutions is set as the threshold value as is, the judgment of thread breakage detection, which will be described later, becomes too strict and there is a risk of frequent detection errors.

[0151] Then, when sewing of the tatami mat 100 begins, the thread 90 is supplied from the original roll of thread 90 to the sewing needle 112 via the encoder roller 94 and the like, while the tatami mat 100 is sewn. At this time, one stroke of the sewing needle 112 is detected by the needle position detection sensor 265, and with each stroke of the sewing needle 112, the actual number of rotations of the encoder roller 94 is saved in the SSD of the computer on the operation panel 85.

[0152] The CPU then compares the actual rotation speed with the rotation speed threshold value determined in (1) above, which corresponds to the thickness of the tatami mat 100 (thick or thin), and determines whether the rotation speed of the encoder-equipped roller 94, which reflects the amount of thread 90 used, is normal or abnormal. A normal state is when the actual rotation speed is greater than or equal to the rotation speed threshold value. An abnormal state is when the actual rotation speed is less than the rotation speed threshold value, and this state is determined to be a thread breakage.

[0153] An abnormal state of thread breakage occurs, for example, when some kind of trouble causes the thread 90 to become tangled midway, the thread 90 to break midway, the bobbin thread to run out, or the thread 90 to run out. When the thread 90 becomes tangled or the bobbin thread to run out, the feed of the thread 90 decreases or stops, and when the thread 90 breaks or runs out, the feed of the thread 90 stops. When this happens, the rotation speed of the encoder roller 94 through which the thread 90 passes decreases or stops, and the measured rotation speed falls below the rotation speed threshold, and it is determined that a thread breakage has occurred.

[0154] When the computer on the operation panel 85 detects a thread breakage, it stops the operation of the Tatami mat sewing device 1. At this time, the sewing needle 112 is configured to stop in its initial position, farthest from the side of the Tatami mat 100. This is because the needle position detection sensor 265 detects the initial position of the sewing needle 112, and the number of rotations of the encoder-equipped roller 94 is detected with each stroke of the sewing needle 112, and thread breakage is determined when the sewing needle 112 has made one stroke and is in its initial position, farthest from the side of the Tatami mat 100.

[0155] And because the sewing needle 112 stops in its initial state, replacing the thread 90 can be done easily compared to replacing the thread when the needle gets stuck in the tatami mat. Also, because the machine automatically performs everything from measuring the tatami mat thickness to detecting thread breakage, human error can be prevented and thread breakage can be detected with precision. Furthermore, when thread breakage is detected, in addition to stopping the operation of the tatami mat sewing device 1, the warning light 86 can also be made to flash or a warning sound can be sounded to warn the operator of the thread breakage.

[0156] In addition, as shown in Figure 15, this detection method 1 is configured to set two threshold levels, one for thick tatami mats and one for thin tatami mats. However, with two threshold levels, when the tatami mat thickness is close to thin, the threshold level may be significantly different from the actual thread breakage, and the thread breakage may not be detected when it should be. In this case, there is a risk that the machine will continue to operate even though the thread has already broken. Therefore, by using the configuration shown in the following method 2, it is possible to detect thread breakage at a threshold level close to the appropriate threshold level.

[0157] (5-2. Thread break detection method 2 (two-stage tatami thickness, stitching method, stitching pitch)) There are several different stitching methods for sewing the sides of tatami mats, including a zigzag stitch, a ladder stitch, an irregular ladder stitch, and a trapezoid stitch (see Figure 16). The stitch pitch can also be short or long depending on the structure and strength of the tatami mat. Naturally, the amount of thread 90 used during sewing varies depending on the stitching method and stitch pitch. Therefore, it is desirable to change the threshold for the number of revolutions depending on the stitching method and stitch pitch, in addition to the tatami mat thickness (needle height). Figure 17 shows the needle height and stitch pitch for zigzag stitch and ladder stitch.

[0158] The Tatami sewing device 1 of this embodiment is configured so that a preset stitching method and stitching pitch can be set on the operation panel 85. Specifically, the operator is configured so that before sewing the Tatami, he or she can input the stitching method and stitching pitch by operating the touch panel of the operation panel 85. The needle height (the height at which the needle is inserted from the bottom of the Tatami), which is determined by the Tatami thickness, is automatically determined by the Tatami thickness measuring means 80 described above.

[0159] Once the stitching method and stitching pitch are determined, threshold values ​​for the rotation speed of the encoder roller 94 are set taking into account the stitching method and stitching pitch for thick and thin tatami mats.

[0160] To set this threshold value for the number of revolutions, for example, 3D CAD and simulation software are used to calculate the amount of thread used for one stitch when the stitch pitch is changed according to the stitching method for thick and thin tatami mats, and this is combined with the amount of thread 90 used in one rotation of the encoder roller 94 to set the threshold value for the number of revolutions of the encoder roller 94. Details of setting this threshold value are the same as those for thread breakage detection method 3, which will be described later.

[0161] With this configuration, the threshold value for the number of rotations of the encoder roller 94 can be set in multiple stages depending on the elements of tatami thickness (thick tatami and thin tatami), stitching method, and stitching pitch, enabling more accurate detection of thread breakage. Also, when thread breakage detection is performed in only two stages, for thick tatami and thin tatami, without taking into account the stitching method or stitching pitch, it may not be detected where it should actually be, but by setting a threshold value that takes into account the stitching method and stitching pitch, it is possible to detect thread breakage in a state close to the actual state.

[0162] However, as shown in Figure 18, even in this case, method 2 has two standards for tatami thickness: thick and thin, and because the stitching method and stitch pitch are added to this, the accuracy near the thresholds for thick and thin tatami increases, but it does not support arbitrary tatami thickness. Therefore, by using the configuration shown in the following method 3, it is possible to perform thread breakage closer to the appropriate threshold.

[0163] (5-3. Thread break detection method 3 (any tatami thickness, stitching method, stitching pitch)) While the above-mentioned thread breakage detection methods 1 and 2 detect thread breakage in two stages of tatami thickness, thick tatami and thin tatami, this thread breakage detection method 3 sets a threshold value according to the desired tatami thickness in addition to the stitching method and stitch pitch, which allows for even more accurate thread breakage detection.

[0164] Specifically, before sewing the tatami mats, the operator can input the stitching method and stitch pitch by operating the touch panel of the operation panel 85. The needle height (the height at which the needle is inserted from the bottom of the tatami mat), which is determined by the tatami mat thickness, is automatically determined by the tatami mat thickness measuring means 80 mentioned above.

[0165] Once the stitching method and stitching pitch are determined, a threshold value for the rotation speed of the encoder-equipped roller 94 is set based on the tatami thickness actually measured by the tatami thickness measuring means 80, taking into account the stitching method and stitching pitch.

[0166] The threshold value for the number of revolutions is calculated, for example, as follows: First, using, for example, 3D CAD and simulation software, the amount of thread used for one pitch when the sewing needle 112 makes one reciprocating movement when the tatami mat thickness (needle height) and stitch pitch are changed according to each stitching method is calculated, and from this, the following formula 1 according to the stitching method is calculated.

[0167] (Formula 1) Simulated thread usage (A) = K1 x needle height distance + K2 x stitch pitch distance (K1 is a coefficient that calculates the amount of thread used in the height direction at the needle height distance according to the sewing method) (K2 is a coefficient that calculates the amount of thread used in the horizontal direction at the stitch pitch distance according to the stitching method.) (If the thread runs diagonally, such as in a zigzag stitch, divide it proportionally in the vertical and horizontal directions.)

[0168] In addition to the simulated thread usage, a tatami mat is actually sewn together using thread, and actual measurement data of the thread usage corresponding to the needle height and stitch pitch according to the sewing method at that time is obtained.Then, the difference between the actual measurement data of thread usage and the simulated thread usage (A) calculated from the above formula 1 is calculated as a correction value (B).The difference in this correction value (B) is then considered as an error, and its absolute value is added to the simulated thread usage (A) to obtain the calculated thread usage (C).

[0169] (Formula 2) Calculated thread usage (C) = Simulated thread usage (A) + Correction value (B)

[0170] As described above, the amount of thread used is calculated according to the stitching method, needle height, and stitch pitch, but if this is used as the threshold value as is, there is a risk that there will be many false detections where the actual amount of thread used is lower than the threshold value due to errors in the amount of thread used or slight snagging of the thread, etc. Therefore, the threshold value is set to be lower than the calculated amount of thread used. Here, if the set value below the threshold value is called the threshold margin value (D), the thread use amount threshold value (E) is calculated using the following formula.

[0171] (Formula 3) Thread usage threshold (E) = calculated thread usage (C) - threshold margin value (D)

[0172] In this way, the threshold value of the yarn usage amount is calculated. The threshold margin value (D) may be stored as a fixed value, or may be configured to be arbitrarily set by the operator operating the operation panel 85.

[0173] Meanwhile, the amount of yarn used that is fed out when the encoder roller 94 makes one rotation is calculated. This amount of yarn used may be calculated from the diameter of the roller, or may be calculated from the actual amount of yarn used and the rotation speed at that time. Then, a rotation speed threshold (F) based on the rotation speed of the encoder roller 94 is calculated using the following formula:

[0174] (Formula 4) Rotation speed threshold (F) = thread consumption threshold (E) / K3 (K3 is a coefficient. The amount of yarn used per rotation of the encoder roller 94)

[0175] In this way, the rotation speed threshold (F) is calculated according to the stitching method, needle height, and stitch pitch. When sewing a tatami mat, the thread 90 is fed from the work roll, and the rotation speed when it passes through the encoder roller 94 is sent to the computer of the operation panel 85 for each stroke of the sewing needle 112. The computer of the operation panel 85 compares the actual rotation speed for each stroke of the sewing needle 112 with the rotation speed threshold (F), and determines that the condition is normal if the actual rotation speed > rotation speed threshold (F), and that the condition is abnormal if the actual rotation speed ≦ rotation speed threshold (F), and if the abnormal condition is met, determines that the thread has broken.

[0176] In the above, the rotation speed threshold value (F) is used to determine whether a yarn breakage has occurred from the measured rotation speed of the encoder roller 94, but it is also possible to use the yarn consumption threshold value (E). In this case, the computer of the operation panel 85 multiplies the measured rotation speed of the encoder roller 94 by the amount of yarn consumption per rotation to calculate the measured amount of yarn consumption, and compares the measured amount of yarn consumption with the yarn consumption threshold value (E) to determine whether a yarn breakage has occurred.

[0177] With the above configuration, it is possible to set a threshold value according to any tatami thickness, stitching style, and stitching pitch, as shown in Figure 19, and therefore the threshold value according to the tatami thickness, etc. can be made a linear threshold value. This allows for even more accurate detection of thread breakage according to the tatami thickness, stitching style, and stitching pitch.

[0178] (6. Other Embodiments) As described above, preferred embodiments of the present invention have been described. However, it goes without saying that the present invention is not limited to the above-described embodiments, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention.

[0179] In the above embodiment, the tatami mat sewing device is used in the backstitching process, but it can also be used in the frame stitching process. Also, the tatami mat thickness measuring means can be applied to tatami mat manufacturing devices other than the tatami mat sewing device.

[0180] The sewing needle is arc-shaped, but may be straight. In the case of an arc-shaped needle, the reciprocating motion is a swinging orbital motion, but in the case of a straight needle, the reciprocating motion is a linear reciprocating motion. [Explanation of symbols]

[0181] 1 Tatami sewing device 10 Sewing machine body 11 Mounting table 11A Roller 12 frames 13 Tatami edge supply reel 20 Sewing mechanism 21 Sewing machine arm 22 needle arm 23 Cam 24 Connecting member 25 Motor for sewing mechanism 26 Kama 30 Lifting mechanism 40 Lifting mechanism motor 50 Handle 51 Handle shaft 52 sprockets 60 Chain 70 Balance 71 Guide roller 80 Tatami thickness measurement method 81 Tatami mat holder 81A Support member 81B Pulley 81C Belt 82 Link mechanism 83 Air Cylinder 84 Encoder 85 Control panel 86 Warning light 90 thread 91 Original fabric 92 Threading 93 Tension Roller 94 Encoder equipped roller 95 Tension roller 96 Thread path 97 Slack removal part 100 tatami mats 110 Side 112 Sewing Needle 112a Through hole 112b Guide groove 113 Sewing needle drive shaft 211 Sewing machine pivot shaft 221 Sewing needle swing shaft 261 Sickle shaft 262 Kama rotation drive shaft 263 Bevel gear 264 Rotation detection plate 264a Sector 265 Needle position detection sensor 701 Balance drive shaft

Claims

1. A tatami mat sewing device for sewing tatami mats, A thread breakage detection means is provided for detecting thread breakage in the sewing thread, The yarn breakage detection means a detection sensor for detecting the amount of yarn used; a control means; A tatami mat sewing device characterized in that the control means determines that a thread breakage has occurred when the actual amount of thread used, measured by the detection sensor, falls below a predetermined threshold value according to the tatami mat thickness or needle height.

2. The yarn breakage detection means The control means A plurality of threshold data according to the tatami thickness or needle height is provided, A predetermined threshold value is selected according to the thickness or needle height of the tatami mat to be sewn. The tatami mat sewing device according to claim 1.

3. The tatami mat sewing device further comprises a tatami mat thickness measuring means for measuring the thickness of the tatami mat, The yarn breakage detection means A predetermined threshold value is selected according to the tatami thickness measured by the tatami thickness measuring means.

3. The tatami mat sewing device according to claim 2.

4. The yarn breakage detection means An input means for inputting the thickness or needle height of the tatami mat to be sewn, A predetermined threshold value is selected according to the input tatami thickness.

3. The tatami mat sewing device according to claim 2.

5. The plurality of threshold data include two threshold data corresponding to a tatami thickness or a needle height of a thick tatami and a thin tatami.

3. The tatami mat sewing device according to claim 2.

6. The yarn breakage detection means The sewing machine further includes an input means for inputting a stitch pitch at the time of sewing, The control means determines that a thread breakage has occurred when the actual thread consumption measured by the detection sensor falls below a threshold calculated based on an estimated thread consumption calculated from the tatami mat thickness or needle height and the stitch pitch during sewing.

3. The tatami mat sewing device according to claim 2.

7. The yarn breakage detection means The input means can further input stitching methods such as ladder stitch and zigzag stitch when sewing, The threshold value calculated by the control means is based on an estimated usage amount calculated based on the tatami mat thickness or needle height and stitching method.

3. The tatami mat sewing device according to claim 2.

8. The tatami mat sewing device further includes a thread holder for holding a sewing thread to be fed, The yarn breakage detection means The sewing machine is characterized in that the detection sensor comprises a roller equipped with an encoder around which the sewing thread passes, on a path from the thread holding unit to the sewing needle.

3. The tatami mat sewing device according to claim 2.

9. The control means calculates the actual amount of thread used by multiplying the number of rotations of the encoder by the amount of sewing thread fed out per one rotation of the encoder.

9. The tatami mat sewing device according to claim 8.

10. The control means calculates the sewing thread fed from the number of rotations of the encoder when the sewing needle makes one reciprocating motion as the actual thread usage amount, and calculates a threshold value from the estimated thread usage amount corresponding to one reciprocating motion of the sewing needle.

10. The tatami mat sewing device according to claim 9.

11. The encoder is provided on the path from the thread holder to the sewing needle, closer to the sewing needle than a tension member that applies tension to the sewing thread, and in the vicinity of the tension member.

9. The tatami mat sewing device according to claim 8.

12. Two of the tension members are provided, The encoder is disposed between the two tension members on a path from the thread holding portion to the sewing needle.

9. The tatami mat sewing device according to claim 8.

13. The sewing machine further includes a sewing machine rotation detection plate that is linked to the operation of the sewing needle, and a needle position detection sensor. When the sewing needle is at a predetermined position, a needle position detection sensor detects the sewing machine rotation detection plate. The tatami mat sewing device according to claim 10.

14. the needle position detection sensor calculates the actual amount of yarn used from the number of revolutions of the encoder in a section from the time when the needle position detection sensor detects the position of the sewing needle to the time when the needle position detection sensor next detects the position of the sewing needle, and compares the actual amount of yarn used with the threshold value corresponding to the section to determine whether a yarn breakage has occurred. The tatami mat sewing device according to claim 13.

15. The needle position detection sensor detects when the tip of the sewing needle is at the farthest position from the side of the tatami mat, Each time the needle position detection sensor detects the position of the sewing needle, the thread breakage determination is performed, and data based on the encoder is recorded and reset. The tatami mat sewing device according to claim 14.

16. The tatami mat thickness measuring means is A tatami mat holder that moves up and down, and a lifting means for lifting and lowering the tatami mat presser, The thickness of the tatami mat is measured by using the movement distance of the tatami mat presser.

4. The tatami mat sewing device according to claim 3.

17. The tatami mat thickness measuring means is The distance between the bottom of the tatami mat and the upper limit position of the tatami mat holder in the standby state is used as a reference distance, Subtract the distance traveled until the tatami mat presser contacts the surface of the tatami mat and stops from the reference distance, It is a means of measuring the thickness of tatami mats.

17. The tatami mat sewing device according to claim 16.

18. The lifting means is a driving means connected to the tatami mat presser; a connecting means for connecting the driving means and the tatami mat presser; an encoder attached to the connection means; The thickness of the tatami mat is measured by measuring the movement distance of the tatami mat presser using the encoder.

17. The tatami mat sewing device according to claim 16.

19. the connecting means has a link mechanism and / or a cam mechanism, the encoder is attached to the link mechanism or the cam mechanism; The encoder converts the amount of rotation of the link or cam that constitutes the link mechanism or the cam mechanism into a height distance, which is used as the moving distance of the tatami mat presser, thereby measuring the thickness of the tatami mat.

19. The tatami mat sewing device according to claim 18.

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