Flat stitch sewing machine

Abstract

To provide a circular object welt sewing device of a cover stitch sewing machine capable of solving problems such as a burden on a worker and a loss of time, and a problem that a seam is sewn in a stretched state.SOLUTION: The round material blind stitching device is provided with a left knife member 3 in front of a presser foot 2, and a fabric guide member 4 in front of and on the right of the left knife member 3, and the fabric guide member 4 is provided with a left side guide 41 which can move straight to the left and right and a right side guide 42 arranged on the right side. The detection member 5 is installed in front of the front side surface of the left side guide 41. Then, the air cylinder 61 is driven in response to the detection of the detection member 5 to move the left side guide 41 and the detection member 5 to the left side, so that the operator can continue the welt sewing to the end of one round without the sewn portion being jammed in the left side guide 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a round hem stitching device for an interlock stitch sewing machine. In the present invention, "front and rear" refers to the front and rear direction in the fabric feed direction, "left and right" refers to the left and right direction when the sewing machine is viewed from the front, and "up and down" refers to the up and down direction of the sewing machine. [Background technology]

[0002] A well-known conventional flat stitch sewing machine for hemming round objects includes a fabric guide member that guides the folded fabric in front of the presser foot and a left knife member that operates continuously in front of the presser foot and to the left of the presser foot during sewing. This allows the hem of a round object, such as a T-shirt or skirt, to be folded inward and guided by the fabric guide member. The inside edge of the folded fabric is then cut by the left knife member, aligning the left and right edges. The folded fabric is then fed to the presser foot for a hemming. While a hemming is possible with a sewing machine that does not have a left knife member, it requires skilled techniques to first finish the fabric edge in a neat, straight line and to prevent the fabric from moving left and right during sewing. The left knife member eliminates this preparatory step and has the advantage of making sewing easier even for inexperienced operators. The fabric guide member includes a left guide member located between the inside fabric and the outside fabric just in front of the left knife member, and a right guide member located to the right of the left knife member and the left guide. The left guide supports the inner fabric from above to prevent it from flapping and shifting position before it is fed to the left knife member, and the right guide assists in positioning the right folded portion of the fabric.

[0003] As the sewing progresses and the sewn portion of the round object makes a full rotation and returns from the front to the left guide, the inner fabric and outer fabric are closed by the sewing, and if left as is, the left guide will get stuck. Therefore, the worker stops the sewing machine just before that point, shifts the unsewn portion in front of the left knife member to the right, positions it above the left guide, returns it to its original left position, and starts the sewing machine again to sew up to the sewn portion and complete one rotation. This requires the worker's attention, which is burdensome, and also causes time loss due to the stoppage. Furthermore, the portion to be sewn when the machine is started after the stop is likely to be misaligned left and right due to the shifting of the fabric, and the front-to-back distance is also likely to vary, resulting in inconsistent quality of the finished product.

[0004] To address this issue, a device such as that described in Patent Document 1 is known. This device does not use a left knife member, but turns a round object inside out, folds the hem to the right side, sews a full lap, and then turns it right side out to complete the felled seam of the round object. This device is provided with a stopper, and when the sewn portion makes a full lap and returns from the front to the left guide, it comes into contact with and presses the stopper, causing the left guide, which is held by the stopper, to move due to the restoring force of a spring, retracting the inner fabric from its position, allowing sewing to continue without stopping the sewing machine.

[0005] However, this device requires two springs, one to hold the stopper in place and one to provide a restoring force to the left guide, and the fabric and seam press against it until the stopper is released from its locked state, causing excessive tension due to the force applied to the fabric and seam during this time, resulting in the problem of the seam being stretched when sewn. Also, if the fabric comes into contact with and presses against the stopper when folding the fabric in half and setting it while the sewing machine is stopped in preparation for sewing, the stopper will be released and the left guide will move, requiring the restoring operation to be performed again, resulting in a loss of time. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 60-9470 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a round-item blunt stitching device for an interlock stitch sewing machine that eliminates the above-mentioned problems of burden on the operator, loss of time, and stretched stitches when blunt stitching round items with an interlock stitch sewing machine having a left knife member and a material guide member. [Means for solving the problem]

[0008] In order to achieve the above object, the invention described in claim 1 is a round hem stitch device for an interlock stitch sewing machine, which is equipped with a fabric guide member that guides the fabric in front of the presser foot, and a left knife member that operates continuously during sewing on the left side of the presser foot, wherein the fabric guide member has a left guide and a right guide, and is equipped with a detection member that is positioned in front of the left guide, and a drive device that drives the left guide and the detection member to the left.

[0009] In order to achieve the above object, the invention described in claim 2 is a round fill stitch device for a flat stitch sewing machine described in claim 1, characterized in that the detection member comprises a sewn portion detection lever having a sewn portion detection portion and an action portion and swinging back and forth, a detection rod arranged in the front-to-back direction of the action portion and moving linearly in the front-to-back direction when the action portion comes into contact with and presses it, a compression coil spring that presses the detection rod in the direction toward the action portion, a permanent magnet fixed to one end of the detection rod, and a Hall sensor that detects the front-to-back movement of the permanent magnet.

[0010] In order to achieve the above object, the invention described in claim 3 is a round lay stitch device for a flat stitch sewing machine described in claim 1 or claim 2, characterized in that it includes a control device that drives the left guide and the detection member to the left by the driving device when the sewn portion detection lever is actuated while the sewing machine is running. [Effects of the Invention]

[0011] The round object hem sewing device of the present invention can eliminate problems such as worker burden, time loss, and stretched seams as follows: When a round object is hemmed and sewing progresses, the sewn portion of the round object makes one full revolution and returns from the front, whereupon the hem comes into contact with the detector located in front of the left guide. This causes the drive device to drive the left guide and the detector to the left. Therefore, the sewn portion does not get stuck in the left guide, and the operator can continue hem until the end of the revolution.

[0012] The detection member includes a sewn portion detection lever that has a sewn portion detection portion and an operating portion and swings back and forth; a detection rod that is positioned in the front-to-rear direction of the operating portion and moves linearly back and forth when the operating portion contacts and presses it; a compression coil spring that presses the detection rod toward the operating portion; a permanent magnet fixed to one end of the detection rod; and a Hall sensor that detects the back-to-back movement of the permanent magnet. This configuration uses the restoring force of a single spring, rather than the multiple springs required in conventional technology. This minimizes the force applied to the fabric and seam, eliminating the problem of excessive tension causing the seam to stretch and become sewn. Furthermore, the use of a Hall sensor, a so-called magnetic detection device, offers the advantage of being less susceptible to false detections caused by dust and lint that accumulates on the detection device, compared to detection devices that require physical contact or optical devices.

[0013] Furthermore, by configuring the device to include a control device that drives the left-side guide and detection member to the left using a drive device when the sewn area detection lever is activated while the sewing machine is running, even if the fabric comes into contact with and pushes against the detection member when folding the fabric in half and setting it while the sewing machine is stopped in preparation for sewing, the left-side guide can be controlled not to operate while the sewing machine is stopped, unlike conventional technology, and there is no need to perform the restoration operation again, nor is there any loss of time. [Brief explanation of the drawings]

[0014] [Figure 1]1 is a perspective view of a sewing machine applied to the present invention, viewed from the front left, in which the positive direction of the X axis indicates the right direction, the positive direction of the Y axis indicates the rearward direction, and the positive direction of the Z axis indicates the upward direction. [Figure 2] 3A and 3B are a plan view and a front view of a fabric guide member of a sewing machine to which the present invention is applied; [Figure 3] 3A and 3B are a bottom view and a cross-sectional view of a detection member of a sewing machine applied to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] An example of an embodiment of the present invention will be described below with reference to Figures 1 to 3. Figure 1 is a perspective view of a sewing machine to which the present invention is applied, seen from the front left. The sewing machine 1 is equipped with a presser foot 2 that is pressed downward by the upper surface of a needle plate 11 when sewing is performed using the cooperation of a needle (not shown) and a looper (not shown), a left knife member 3 that cuts the left edge of the fabric to align it in a straight line using the cooperation of an upper blade (not shown) that swings up and down on the front left of the presser foot 2 and a lower blade (not shown) fixed to the sewing machine 1 when the fabric is fed rearward during sewing using the cooperation of a feed dog (not shown) and the presser foot 2, and a fabric guide member 4 that is located in front of and to the right of the left knife member 3 and guides the top, bottom, and left and right edges of the fabric to keep them in a constant position.

[0016] FIG. 2 shows a plan view and a front view of a fabric guide member of a sewing machine according to the present invention. The fabric guide member 4 includes a fabric guide member base 40 fixed to the front of the sewing machine 1, with its upper surface generally flush with the upper surface of the needle plate 11; a left guide 41 positioned on the fabric guide member base 40 with a certain gap from its upper surface and capable of linear movement to the left and right; and a right guide 42 positioned to the right of the left knife member 3 and the left guide 41 with a certain gap and capable of linear movement to the left and right. The fabric guide member base 40 is an L-shaped bent plate, with one side fixed as the upper side generally flush with the upper surface of the needle plate 11, and the other side standing upright downward and away from the front of the left knife member 3 as the front side. An air cylinder 61 is fixed to the rear surface on the right side of the front side of the fabric guide member base 40, with its shaft drivable to the left and right. This may be a linearly moving drive device such as a solenoid.

[0017] The left guide 41 is an L-shaped bent plate, with one side serving as the upper side and positioned with a certain gap from the top surface of the fabric guide member base 40. The other side serves as the front side and is connected to the shaft of the air cylinder 61 by a connecting plate 63 in front of the front side of the fabric guide member base 40. The connecting plate 63 is positioned to slide on the backside of the right side of the front side of the fabric guide member base 40 and to be able to move linearly left and right. As a result, when the air cylinder 61 drives its shaft left and right, the connecting plate 63 drives left and right, thereby driving the left guide 41 left and right. During sewing, the left guide 41 is basically positioned in the rightmost position. The upper side of the left guide 41 also protrudes to the right relative to the front side. When viewed from the front, the gap between the backside of the right-protruding part of the upper side of the left guide 41 and the upper side of the fabric guide member base 40 can be seen. When performing a blunt seam on a round item, the folded fabric is guided through this gap.

[0018] The right guide 42 is block-shaped and has a concave left side when viewed from the front, and is positioned so that when the left guide 41 is positioned at the rightmost position, the right end of the part that protrudes to the right on the upper side of the left guide 41 fits into the concave part on the left side of the right guide 42, leaving a certain gap. The right guide 42 is also positioned to slide on the upper side of the fabric guiding member base 40, and is connected to an air cylinder 62, which is a driving device fixed to the right, so that it can be driven left and right as necessary. During sewing, the right guide 42 is basically positioned at the leftmost position.

[0019] The detection member 5 is installed in front of the front side surface of the left guide 41. When the air cylinder 61 drives its shaft left and right, the connecting plate 63 drives left and right, which drives the left guide 41 left and right, and further drives the detection member 5 left and right together.

[0020] 3 shows a bottom view and a cross-sectional view of a detection member of a sewing machine that is applicable to the present invention. The detection member 5 includes a detection member base 50, a sewn portion detection lever 51, a bracket 52, a detection rod 53, a compression coil spring 54, a permanent magnet 55, and a Hall sensor 56. The detection member base 50 is an L-shaped bent plate, with one side serving as the upper side generally coinciding with the upper side of the left guide 41, and the other side serving as the rear side, fixed flush with the front surface of the front side of the left guide 41. The right end of the upper side of the detection member base 50 generally coincides with the right end of the front side of the left guide 41.

[0021] The sewn-portion detection lever 51 is plate-shaped and is arranged so that its longitudinal axis faces the backside of the upper surface of the detection member base 50 and slides flush against it. The right side of the sewn-portion detection lever 51 protrudes from the right edge of the upper surface of the detection member base 50 and is located in front of the right-side protruding portion of the upper surface of the left guide 41 mentioned above, while the left side is hidden by the backside of the upper surface of the detection member base 50. The middle part of the sewn-portion detection lever 51 is inserted into a shaft member 501 fixed to a position left of the right edge of the upper surface of the detection member base 50, and the lever swings back and forth around this shaft member. The front surface of the right end of the sewn-portion detection lever 51 forms the sewn-portion detection portion 511, which serves as the force point when the fabric or a seam comes into contact with the sewn-portion detection lever. The front surface of the left end forms the action portion 512, and when the sewn-portion detection portion 511 is pushed backward by the fabric or a seam, the action portion 512 swings forward. In the state shown in FIG. 3, the sewn portion detection lever 51 is already pressed, the sewn portion detection portion 511 at the right end of the sewn portion detection lever 51 has moved rearward, and the action portion 512 at the left end has moved forward.

[0022] The bracket 52 is block-shaped with a U-shaped groove formed in one portion thereof, and is fixed to the back surface of the upper surface of the detection member base 50 so that the open portion of the U-shaped groove is located in front of the action portion 512 of the sewn portion detection lever 51. A shaft hole is formed in the inner surface of the U-shaped groove of the bracket 52. The detection rod 53 has a block-shaped portion formed on one end of its shaft, and the shaft is inserted into and passes through the shaft hole of the bracket 52. Both side surfaces of the block-shaped portion are guided by sliding guide portions 521, which are the inner surfaces of the U-shaped groove of the bracket 52, and is positioned in front of the action portion 512. When the action portion 512 comes into contact with and presses against this, the detection rod 53 moves linearly forward. The compression coil spring 54 is inserted onto the axis of the detection rod 53 inside the U-shaped groove of the bracket 52, between the inner surface of the U-shaped groove of the bracket 52 and the front surface of the block-shaped portion of the detection rod 53, and thereby presses the detection rod 53 backward, i.e., in the direction toward the acting portion 512.

[0023] Holder 551 is fixed to the front end of the shaft of detection rod 53, away from acting portion 512. Permanent magnet 55 is fixed to the lower end of holder 551, and thus permanent magnet 55 moves back and forth as detection rod 53 moves back and forth. Hall sensor 56 is fixed to the back surface of the upper surface of detection member base 50. Hall sensor 56 is located forward on the line of movement of permanent magnet 55, with Hall sensor detection position 561 that detects magnetism facing upward, and thereby detects the back and forth movement of permanent magnet 55.

[0024] With the above-described configuration, as the hem of a round object is sewn, the sewn portion of the object makes one full revolution and returns from the front. The sewn portion comes into contact with the sewn portion detecting portion 511 of the sewn portion detecting lever 51 of the detecting member 5 located in front of the left guide 41. The sewn portion detecting lever 51 then swings, causing the operating portion 512 to swing and push the front detecting rod 53, moving the permanent magnet 55, which is detected by the Hall sensor 56. In response to the detection by the Hall sensor 56, the air cylinder 61 is driven to move the left guide 41 and the detecting member 5 to the left. This prevents the sewn portion from getting stuck in the left guide 41, allowing the operator to continue the hem until the end of one revolution. Furthermore, this configuration uses the restoring force of a single spring, rather than the multiple springs required in conventional technology. This minimizes the force applied to the fabric and seam, eliminating the problem of excessive tension causing the seam to be stretched.

[0025] The present invention may also be provided with a control device that drives the left guide 41 and the detection member 5 to the left by the drive device 6 when the sewn portion detection lever 51 is activated while the sewing machine is running. This allows the hem stitching of a rounded item to be performed using the following sequence and control. First, while the sewing machine is stopped, the left guide 41 is moved to the left. At this time, the right guide 42 may also be moved to the right. The worker folds the hem of the rounded item to an appropriate width and sets it on the sewing machine 1. Then, by operating a switch linked to the control device, the left guide 41 is moved to the right. At the same time, if the right guide 42 is on the right, it is moved to the left. The fabric is then adjusted so that it fits along the left guide 41 and right guide 42, and preparation for sewing is complete. During this process, the detection member 5 is activated but the left guide 41 does not move.

[0026] From this point, the sewing machine 1 is operated to perform sewing. The hem of the round item is guided by the fabric guide member 4 and fed backward. The folded inner fabric edge is cut by the left knife member 3 to align the left and right sides. The folded fabric is then fed to the presser foot 2 and sewn. As sewing progresses, the sewn portion of the round item makes one full rotation and returns from the front to the sewn portion detection lever 51 in front of the left guide 41. The fabric, whose inner and outer sides have been closed by the sewing, comes into contact with and presses against this. The drive device 6, which operates while the sewing machine is running, drives the left guide 41 and detection member 5 to the left, allowing the operator to complete sewing one full rotation of the round item. Once sewing is complete, the sewing machine 1 is stopped and the fabric is removed. At this point, the left guide 41 has moved left, allowing the above process to be repeated.

[0027] Therefore, by adopting the above-described configuration, even if the fabric comes into contact with and pushes the sewn portion detection lever 51 of the detection member 5 when the fabric is folded in half and set while the sewing machine is stopped in preparation for sewing, the left side guide 41 can be controlled not to operate while the sewing machine is stopped, unlike conventional technology, and there is no need to perform the restoration operation again, and no time is lost.

[0028] The above-described round hem stitching device for an interlock stitch sewing machine is equipped with a left guide and a right guide, a detector positioned in front of the left guide, and a drive mechanism for driving the left guide and detector to the left, thereby eliminating problems such as increased operator burden, lost time, and stretched stitches.

[0029] The present invention is not limited to the above-described embodiment, and those skilled in the art can make various modifications to the above-described embodiment without departing from the spirit of the present invention, and the present invention also encompasses such modifications. Furthermore, although this embodiment uses a flat stitch sewing machine, the present invention is not limited to this, and can also be implemented with, for example, a single-needle or multi-needle double chain stitch sewing machine equipped with a presser foot similar to that of a flat stitch sewing machine. [Explanation of symbols]

[0030] 1 sewing machine 2 presser foot 3 Left female part 4 Fabric guide member 5. Detection member 6. Drive equipment 11 Throat plate 40 Fabric guide member base 41 Left side guide 42 Right side guide 50 Detection member base 51 Sewing area detection lever 52 Bracket 53 Detection rod 54 Compression coil spring 55 Permanent Magnets 56 Hall sensor 61 Air cylinder 62 Air cylinder 63 Connecting plate 501 Shaft member 511 Pre-sewn part detection unit 512 Action part 521 Sliding guide 551 Holder 561 Hall sensor detection position

Claims

1. A round hem stitching device for an interlock stitch sewing machine is provided with a fabric guide member that guides the fabric in front of the presser foot, and a left knife member that operates continuously during sewing on the left side of the presser foot, wherein the fabric guide member has a left guide and a right guide, and the device is provided with a detection member that is located in front of the left guide, and a drive device that drives the left guide and the detection member to the left.

2. 2. The round hem stitching device for the interlock stitch sewing machine according to claim 1, wherein the detection member comprises: a sewn portion detection lever having a sewn portion detection portion and an action portion and swinging back and forth; a detection rod arranged in the front-to-rear direction of the action portion and moving linearly back and forth when the action portion comes into contact with and presses the detection rod; a compression coil spring that presses the detection rod in the direction toward the action portion; a permanent magnet fixed to one end of the detection rod; and a Hall sensor that detects the back-to-back movement of the permanent magnet.

3. 3. The round hem stitching device for an interlock stitch sewing machine according to claim 1, further comprising a control device that drives the left guide and the detection member leftward by the drive device when the sewn portion detection lever is actuated during operation of the sewing machine.

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