Overlock sewing machine presser foot lifting and feed dog tilt adjustment device

Abstract

This device for adjusting the presser foot lift and feed dog tilt of an overlock sewing machine solves problems such as the increased cost and price of the sewing machine due to the need for separate drive mechanisms for presser foot lift and drop feed compared to conventional methods, and the inability of these drive mechanisms to adjust the tilt of the differential feed dog. [Solution] The presser foot lifting and feed dog tilt adjustment device of the overlock sewing machine comprises a stepping motor 5, a feed dog tilt adjustment member 3 that is linked to the stepping motor 5, a presser foot lifting member 4 that is linked to the stepping motor 5, and a control device for the stepping motor 5.

Description

Technical Field

[0001] The present invention relates to a device for adjusting the pressing-up and feed tooth inclination of an overlock sewing machine. In the present invention, "front and rear" refers to the front and rear directions in the fabric feeding direction, "left and right" refers to the left and right directions when the sewing machine is viewed from the front, and "up and down" refers to the up and down directions of the sewing machine.

Background Art

[0002] As a conventional presser device for an overlock sewing machine, a device having a solenoid, which is a driving device for raising the presser, is known (for example, see Patent Document 1). Further, as a conventional feeding device for an overlock sewing machine, a device having an air cylinder, which is a driving device for lowering the main feed teeth and differential feed teeth from the upper surface of the needle plate downward, is known (for example, see paragraph numbers 0032, 0033, 0034 and FIGS. 10, 11, 12 of Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In conventional techniques, when an overlock sewing machine finishes sewing and stops, the needle waits at top dead center, and similarly, the main feed dog and differential feed dog also wait at top dead center. When the presser foot is then raised using a drive mechanism to place the fabric on the needle plate, the main feed dog and differential feed dog, which protrude from the top surface of the needle plate, get in the way, requiring the fabric to be lifted slightly before being placed in the desired location for sewing. For small pieces of fabric such as collars and short sleeves, this involves lifting the fabric slightly, placing it in the desired location, and repeating the same operation if the location is not right, which, while not requiring great force, takes some time. For larger pieces of fabric such as the sides of trousers or the hems of curtains, the weight of the fabric adds to the burden, and the repetition of this work results in extra time and significant fatigue. To reduce these burdens, by using a separate drive mechanism to lower the main feed dog and differential feed dog from the top surface of the needle plate, the fabric can be slid in from the side of the needle plate without the main feed dog and differential feed dog getting in the way.

[0005] Thus, the drive for raising the presser foot when the sewing machine stops, known as the presser foot lift, and the drive for lowering the main feed dog and differential feed dog from the top surface of the needle plate, known as the drop feed, required separate drive devices, which contributed to the increased cost and price of the sewing machine. Furthermore, solenoids and air cylinders were commonly used as drive devices for the drop feed and presser foot lift, and these drive the machine in one continuous motion from top dead center to bottom dead center. Depending on the sewing conditions, for example, to adjust the puckering of the fabric or to increase the force of feeding the fabric when there are overlapping sections or thick parts such as tape in the middle of the fabric, it was necessary to tilt the differential feed dog forward upward, or to tilt the differential feed dog forward to a certain extent downward to simply reduce the stitch pitch for fray prevention. In such cases, the drop feed drive device could not handle these situations, and separate components or devices were required.

[0006] The object of the present invention is to provide a device for adjusting the presser foot lift and feed dog tilt of an overlock sewing machine that solves the problems of requiring separate drive devices for presser foot lifting and drop feeding, which increases the cost and price of the sewing machine, and the inability of these drive devices to adjust the tilt of the differential feed dog. [Means for solving the problem]

[0007] To achieve the above objective, the invention described in claim 1 is an overlock sewing machine comprising a needle that moves up and down reciprocatingly, an upper looper and a lower looper that move left and right reciprocatingly in conjunction with the needle, a needle plate installed on the sewing machine body that supports the fabric from below, a presser foot that supports the fabric from above, and a main feed dog and a differential feed dog that move up and down and back and forth, characterized in that the presser foot lifting and feed dog tilt adjustment device comprises a stepping motor, a feed dog tilt adjustment member that is linked to the stepping motor, a presser foot lifting member that is linked to the stepping motor, and a control device for the stepping motor.

[0008] To achieve the above objective, the invention described in claim 2 is a device for adjusting the presser foot lift and feed dog inclination of an overlock sewing machine as described in claim 1, the device for adjusting the presser foot lift and feed dog inclination comprising: a drive crank to which the presser foot lifting member is fixed to the motor shaft of the stepping motor; a presser foot lifting drive link to which one end is connected to the drive crank; a presser foot lifting drive lever to which the other end of the presser foot lifting drive link is connected; an intermediate crank to which the pivoting center and pivoting end of the presser foot lifting drive lever are connected and which pivots together when the engaging portion of the presser foot lifting drive lever contacts and presses; and the intermediate crank inserted into a shaft hole provided in the pivoting center of the intermediate crank The present invention is characterized by comprising: an axle pin that is installed to be pivotable; a press-up link, one end of which is connected to another pivoting end of the intermediate crank that is not connected to the press-up driving lever; a press-up lever, the other end of which is connected to the pivoting end of the press-up link, and whose axle hole provided at the pivoting center is pivotably inserted into the press-up base shaft; a press-up shaft crank fixed to the press-up base shaft on the side of the press-up lever; and a press-up height adjustment screw, which is inserted into a screw hole provided in the press-up shaft crank, with the screw tip protruding and fixed, and which causes the press-up shaft crank and the press-up lever to pivot together when the engaging part of the press-up lever makes contact and presses.

[0009] To achieve the above objective, the invention described in claim 3 is a device for adjusting the presser foot lift and feed dog tilt of an overlock sewing machine as described in claim 2, characterized in that the device for adjusting the presser foot lift and feed dog tilt includes a presser foot height sensor member for detecting the vertical position of the presser foot.

[0010] To achieve the above objective, the invention described in claim 4 is a presser foot lifting and feed dog tilt adjustment device for an overlock sewing machine as described in any one of claims 1 to 3, characterized in that the presser foot lifting and feed dog tilt adjustment device comprises a drive cam fixed to the motor shaft of the stepping motor, a feed dog tilt adjustment lever that swings in conjunction with the drive cam, a feed dog tilt adjustment link with one end connected to the feed dog tilt adjustment lever, and an eccentric shaft crank connected to the other end of the feed dog tilt adjustment link and fixed at the pivot point to the body shaft of an eccentric shaft installed in the sewing machine body.

[0011] To achieve the above objective, the invention described in claim 5 is a presser foot lifting and feed dog tilt adjustment device for an overlock sewing machine as described in claim 4, characterized in that the presser foot lifting and feed dog tilt adjustment device comprises a feed dog tilt adjustment region, a presser foot lifting region, and a transition region in the cam contour in which the driving cam is interlocked with the feed dog tilt adjustment lever. [Effects of the Invention]

[0012] The presser foot lifting and feed dog tilt adjustment device of the present invention addresses the problems of increased sewing machine costs and prices due to the need for separate drive devices for presser foot lifting and drop feed, and the inability of these drive devices to adjust the tilt of the differential feed dog. In an overlock sewing machine equipped with a needle that moves up and down, an upper looper and a lower looper that move back and forth in conjunction with the needle, a needle plate installed on the sewing machine body that supports the fabric from below, a presser foot that supports the fabric from above, and a main feed dog and a differential feed dog that move up and down and back and forth, the presser foot lifting and feed dog tilt adjustment device comprises a stepping motor, a feed dog tilt adjustment member that is linked to the stepping motor, a presser foot lifting member that is linked to the stepping motor, and a control device for the stepping motor. This allows for the use of a single drive device for presser foot lifting and drop feed, thereby suppressing the increase in sewing machine costs and prices, and enabling adjustment of the tilt of the differential feed dog by the feed dog tilt adjustment member. [Brief explanation of the drawing]

[0013] [Figure 1] A perspective view from the left rear of the sewing machine to which the present invention applies. The positive direction of the X axis is to the right, the positive direction of the Y axis is to the rear, and the positive direction of the Z axis is to the upward. [Figure 2] A plan view of the feed dog tilt adjustment member of a device for adjusting the presser foot lift and feed dog tilt of a sewing machine, as applied to the present invention. [Figure 3] A left side view of the feed dog tilt adjustment member of a device for adjusting the presser foot lift and feed dog tilt of a sewing machine, as applied to the present invention. [Figure 4] A plan view of the presser foot lifting member of a device for adjusting the presser foot lifting and feed dog tilt of a sewing machine, as applied to the present invention. [Figure 5] A left side view of the presser foot lifting member of a device for adjusting the presser foot lifting and feed dog tilt of a sewing machine, as applied to the present invention. [Figure 6] A left side view illustrating the operation of the feed dog tilt adjustment member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. [Figure 7] A left side view showing the first stage of the feed dog tilt adjustment member and the presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. [Figure 8] A left side view showing the second stage of the feed dog tilt adjustment member and the presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. [Figure 9] A left side view showing the third stage of the feed dog tilt adjustment member and the presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. [Figure 10] A left side view showing the fourth stage of the feed dog tilt adjustment member and the presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. [Figure 11] A left side view showing the fifth stage of the feed dog tilt adjustment member and the presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. [Figure 12] Left side view of the presser foot height sensor member and air presser foot pressure member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] An example of an embodiment of the present invention will be described below based on FIGS. 1 to 12. FIG. 1 is a perspective view of a sewing machine to which the present invention is applied, seen from the left rear. The positive direction of the X-axis indicates the right direction, the positive direction of the Y-axis indicates the rear direction, and the positive direction of the Z-axis indicates the upward direction. As is well known, the sewing machine 1 includes a needle (not shown) that moves up and down, a needle plate 11 installed on the sewing machine body 10, an upper looper (not shown) and a lower looper (not shown) that reciprocate left and right while sandwiching the needle near the needle plate 11, and they cooperate to perform sewing. The presser 12 is vertically movable and is arranged on the upper surface of the needle plate 11 in a state of being pressed from above, and sandwiches and presses and grips the fabric being sewn from above.

[0015] The presser base 13 is arranged to extend in a branched shape back and forth behind the needle, and a shaft portion provided in the left-right direction at the lower part of the front end is inserted into a bearing portion provided in the middle portion of the presser 12, thereby making the presser 12 swingable and supporting it from above. Thus, when the front end of the presser base 13 rises, the presser 12 also rises, and the presser 12 swings around its bearing portion. The presser bar 14 has its longitudinal direction vertical and is tilted slightly upward and backward at an angle, and grips the presser base 13 from above slightly behind the front end of the presser base 13. The presser bar spring 15 presses from the upper end of the presser bar 14, thereby pressing the presser base 13 and the presser 12, and the presser base joint 16 is connected to the rear end of the presser base 13 that extends in a branched shape, making the presser base 13 swingable laterally. The presser base shaft 17 has its axial direction in the left-right direction and is swingably connected to the presser base joint 16 at the left end, and the presser base bearing 18 is installed behind the sewing machine body 10 and swingably supports the middle portion of the presser base shaft 17.

[0016] Thus, when no external force acts, the presser 12 is pressed against the needle plate 11 from above by the presser bar spring 15 and is stationary on the needle plate 11 due to the presser bar 14 gripping the presser base 13 on the left and right. When the presser 12 is lifted upward, it swings upward around the presser base shaft 17 at the rear of the presser base 13 as the swing center. Also, if only the presser bar 14 is lifted against the force of the presser bar spring 15, the presser base 13 and the presser 12 are released from the grip of the upper presser bar 14 and become swingable laterally at the connecting portion with the presser base joint 16 at its rear end.

[0017] The main shaft (not shown) is rotatably arranged in the sewing machine body 10 with the axial direction being the left - right direction, and is rotated by a driving device such as a servo motor. The rotation of the main shaft is transmitted through various mechanical elements and serves as the driving force for the up - and - down movement of the needle on the left side, the left - right reciprocating movement of the upper looper and the lower looper, and the movement of the feeding mechanism 2, etc. The feeding mechanism 2 gives a periodic movement, for example, an elliptical movement when viewed from the side, which combines the up - and - down movement and the front - and - back movement to the main feeding teeth 20 and the differential feeding teeth 21 installed in front of the main feeding base 22 and the differential feeding base 23.

[0018] In the feeding of the sewing fabric, every time the needle, the upper looper, and the lower looper form a stitch once, the fabric is moved backward by the distance of the stitch pitch. This is done when the needle passes through the fabric on the upper surface of the needle plate 11 and moves upward. The main feeding teeth 20 at the rear and the differential feeding teeth 21 at the front rise from below the groove provided in the needle plate 11 to the upper surface of the needle plate 11, support the fabric from below, and move from the front to the rear while pressing it with the lower surface of the presser 12. When the needle descends again and pierces the fabric, the main feeding teeth 20 and the differential feeding teeth 21 have already retreated below the needle plate 11, and the sewing is performed while the fabric is held between the lower surface of the presser 12 and the upper surface of the needle plate 11. The stitch pitch is generally determined by the distance that the main feeding teeth 20 and the differential feeding teeth 21 move back and forth on the upper surface of the needle plate 11.

[0019] The main feeding base 22 and the differential feeding base 23 are plate - shaped. The main feeding base 22 is on the right side and the differential feeding base 23 is on the left side, and they are arranged face - to - face and slidably. There are U - shaped bifurcated parts behind and in front of the main feeding base 22 and the differential feeding base 23. Inside the bifurcated parts, the rectangular parallelepiped - shaped rear - upper - lower corner pieces 24 of the feeding base and the front - upper - lower corner pieces 25 of the feeding base are arranged such that their upper and lower surfaces are guided and slidable. Axial holes penetrating in the left - right direction are formed in the centers of the rear - upper - lower corner pieces 24 of the feeding base and the front - upper - lower corner pieces 25 of the feeding base. The front - upper - lower corner pieces 25 of the feeding base are inserted into the eccentric shaft part (not shown) provided on the left side of the middle part of the main shaft through their axial holes. When the main shaft rotates, the front - upper - lower corner pieces 25 of the feeding base move up - and - down and front - and - back, and the main feeding base 22 and the differential feeding base 23 whose upper and lower surfaces are guided move up - and - down accordingly.

[0020] At the rear of the main shaft, the eccentric shaft 26 protrudes its eccentric shaft portion to the left, and the shaft portion on the body side is inserted into a shaft hole provided in the sewing machine body 10. The rear upper and lower corner blocks 25 of the feed table are inserted into the eccentric shaft portion of the eccentric shaft 26. As a result, when the main shaft rotates, the front upper and lower corner blocks 24 of the feed table move up and down, causing the front of the main feed table 22 and differential feed table 23 to move up and down, while the rear upper and lower corner blocks 25 of the feed table restrict the up and down movement at the rear of the main feed table 22 and differential feed table 23, creating an inclination.

[0021] By rotating and fixing the eccentric shaft 26, the main feed table 22 and differential feed table 23 can be given various inclinations, such as: a state where the main feed teeth 20 and differential feed teeth 21 are generally horizontal only near the top dead center and inclined at other positions; a state where the upper ends of the main feed teeth 20 and differential feed teeth 21 are generally horizontal when they coincide with the upper surface of the needle plate 11 on the way from the front dead center to the top dead center and are inclined at other positions; a state where the front of the main feed teeth 20 and differential feed teeth 21 are always inclined upward when moving from the front dead center through the top dead center to the rear dead center; a state where the front of the main feed teeth 20 and differential feed teeth 21 are always inclined downward when moving from the front dead center through the top dead center to the rear dead center; and a state where the front is inclined significantly downward so that the upper ends of the main feed teeth 20 and differential feed teeth 21 do not protrude from the upper surface of the needle plate 11 even at the top dead center, a so-called drop feed state.

[0022] Figure 2 is a plan view of the feed dog tilt adjustment member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention, and Figure 3 is a left side view of the feed dog tilt adjustment member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. The presser foot lifting and feed dog tilt adjustment device comprises a stepping motor 5, a feed dog tilt adjustment member 3 that is linked to the stepping motor 5, and a control device (not shown) and an input device (not shown) for the stepping motor 5. The stepping motor 5 is fixed to a motor mounting base 50 installed at the rear of the sewing machine body 10 by screw fastening with the motor shaft facing left. The stepping motor 5 is equipped with a control device and an input device and can be operated during sewing or before and after sewing. The input device may be a known type such as an LCD panel and buttons or a touch panel.

[0023] In this embodiment, the feed dog tilt adjustment member 3 comprises a driving cam 30 fixed to the motor shaft of the stepping motor 5, a feed dog tilt adjustment lever 31 that swings in conjunction with the driving cam 30, a shaft pin 32 inserted through a shaft hole provided at the pivot center of the feed dog tilt adjustment lever 31 and installed on the motor mounting base 50, a feed dog tilt adjustment link 33 with one end connected to the pivot end of the feed dog tilt adjustment lever 31, and an eccentric shaft crank 34 connected to the other end of the feed dog tilt adjustment link 33 and fixed at the pivot center to the body shaft portion 261 (the aforementioned body-side shaft portion) of the eccentric shaft 26 installed on the sewing machine body 10.

[0024] A cam follower 310 is installed in the middle of the feed tooth tilt adjustment lever 31, and the cam contour of the drive cam 30 and the cam follower 310 are pressed against each other by a spring (not shown), thereby causing them to move in conjunction. Alternatively, the cam follower 310 may be omitted, and the drive cam 30 may be in direct contact with the middle of the feed tooth tilt adjustment lever 31.

[0025] As described above, when the motor shaft of the stepping motor 5 rotates, the drive cam 30 causes the feed tooth tilt adjustment lever 31 to swing, which in turn causes the eccentric shaft crank 34 to swing via the feed tooth tilt adjustment link 33, causing the eccentric shaft portion 260 (the aforementioned eccentric shaft portion) of the eccentric shaft 26 to swing, thereby allowing various inclinations to be applied to the main feed teeth 20 and the differential feed teeth 21.

[0026] Figure 4 is a plan view of the presser foot lifting member of a presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention, and Figure 5 is a left side view of the presser foot lifting member of a presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. The presser foot lifting and feed dog tilt adjustment device includes a presser foot lifting member 4 that is linked to a stepping motor 5. In this embodiment, the presser foot lifting member 4 includes a drive crank 40 fixed to the motor shaft of the stepping motor 5, a presser foot lifting drive link 41 with one end connected to the drive crank 40, a presser foot lifting drive lever 42 connected to the other end of the presser foot lifting drive link 41, an intermediate crank 43 whose pivot center and pivot end are connected to the presser foot lifting drive lever 42 and which pivots together when the engaging portion 420 of the presser foot lifting drive lever 42 contacts and presses, and an axis pin 44 inserted through an axis hole provided in the pivot center of the intermediate crank 43, which allows the intermediate crank 43 to pivot.

[0027] In this embodiment, the press-up member 4 includes a press-up link 45, one end of which is connected to another pivoting end of the intermediate crank 43 that is not connected to the press-up driving lever 42; a press-up lever 46, the other end of which is connected to the pivoting end of the press-up link 45 and has a shaft hole provided at the pivoting center that is pivotably inserted into the press-up base shaft 17; a press-up shaft crank 47 fixed to the press-up base shaft 17 on the side of the press-up lever 46; and a press-up height adjustment screw 48, which is inserted into a screw hole provided in the press-up shaft crank 47 and fixed with the screw tip protruding, causing the press-up shaft crank 47 and the press-up lever 46 to pivot together when the engaging portion 460 of the press-up lever 46 makes contact and presses.

[0028] In the state shown in Figure 4, the presser foot 12 is held stationary, pressed against the needle plate 11 from above by the presser bar spring 15. From this position, the drive crank 40 rotates, causing the presser lift drive link 41 to move downward. This causes the presser lift drive lever 42 to swing downward, and the engaging portion 420 located in the middle of the presser lift drive lever 42 (near the pivot point in Figure 4) contacts and presses against the intermediate crank 43 from above, causing the intermediate crank 43 to swing downward. Then, the presser lift link 45, connected to another pivot end of the intermediate crank 43, moves downward, causing the presser lift lever 46 to swing downward. The engaging portion 460 of the presser lift lever 46 is located in front of the presser height adjustment screw 48, and as the presser lift lever 46 swings downward, it contacts and presses against the presser height adjustment screw 48, causing the presser lift shaft crank 47 to swing downward and the presser base shaft 17 to swing (counterclockwise in Figure 4). Then, the oscillation of the presser base shaft 17 causes the presser 12 to swing upward through the presser base 13. The lifting mechanism is driven in this way.

[0029] Furthermore, when the drive crank 40 is stationary and the presser foot 12 is lifted upward, the presser foot shaft 17 swings through the presser foot base 13 and the presser foot base joint 16. At this time, the presser foot lifting shaft crank 47 fixed to the presser foot shaft 17 swings, but the protruding tip of the presser foot height adjustment screw 48 fixed to the presser foot lifting shaft crank 47 moves away from the engaging portion 460 of the presser foot lifting lever 46 (counterclockwise as seen in Figure 4), and therefore does not press the presser foot lifting lever 46. Consequently, even when the main feed dogs 20 and differential feed dogs 21 move upward to lift the fabric and lift the presser foot 12 upward during sewing, the engaging portion 460 of the presser foot lifting lever 46 is not pressed, and therefore the operation is not restricted.

[0030] In the state shown in Figure 4, the presser foot bottom dead center adjustment screw 49 is inserted into a screw hole provided in the motor mounting base 50, with its tip protruding and fixed, and in contact with the engagement portion 430 of the intermediate crank 43. If the presser foot bottom dead center adjustment screw 49 is further tightened from here, slightly increasing the protrusion of the screw tip, the engagement portion 430 of the intermediate crank 43 is pressed, causing the intermediate crank 43 to swing, the presser foot lifting link 45 to move downward, the presser foot lifting lever 46 to swing downward and contact the presser foot height adjustment screw 48, pressing it backward, the presser foot lifting shaft crank 47 to swing downward, and the presser foot 12 is lifted upward. This keeps the presser foot 12 slightly elevated so that it does not contact and press against the upper surface of the needle plate 11 at the bottom dead center, and in cases where there is no fabric between the presser foot 12 and the needle plate 11, such as when forming an empty loop, it is possible to suppress the generation of scratches and noises caused by the collision between the presser foot 12 and the needle plate 11.

[0031] Figure 6 is a left side view showing the operation of the feed dog inclination adjustment member of a presser foot lifting and feed dog inclination adjustment device for a sewing machine applied to the present invention. In this embodiment, the drive cam 30 has a cam contour that is linked to the feed dog inclination adjustment lever 31, and includes a feed dog inclination adjustment region 300, a presser foot lifting region 301, and a transition region 302. In Figure 6, in the order of the top, middle, and bottom figures, the motor shaft of the stepping motor 5 rotates clockwise as seen in the figure, and the swinging end of the feed dog inclination adjustment lever 31 rises while the cam follower 310 of the feed dog inclination adjustment lever 31 is in contact with the feed dog inclination adjustment region 300 of the drive cam 30. At this time, as the feed dog inclination adjustment link 33 rises, the eccentric shaft crank 34 swings clockwise as seen in the figure, and the eccentric shaft 26 rotates. Therefore, as described above, various inclinations are given to the main feed dog 20 and differential feed dog 21.

[0032] As the driving cam 30 rotates further clockwise in the lower diagram of Figure 6, the cam follower 310 of the feed tooth inclination adjustment lever 31 moves beyond the feed tooth inclination adjustment region 300 of the driving cam 30 and comes into contact with the press-up region 301. The cam contour in the press-up region 301 is a circular region that shares the same center as the rotation center of the driving cam 30, and in this region the cam follower 310 does not move up or down. As the driving cam 30 rotates further, it moves beyond the press-up region 301 to the transition region 302. The transition region 302 is a region formed to smoothly connect the cam contours of the feed tooth inclination adjustment region 300 and the press-up region 301.

[0033] Figure 7 is a left side view showing the first stage of the feed dog tilt adjustment member and the presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. In the first stage, the cam follower 310 of the feed dog tilt adjustment lever 31 is in contact with the middle part of the feed dog tilt adjustment region 300 of the drive cam 30. This is the same state as the central diagram in Figure 6, where the axis center of the eccentric shaft portion 260 of the eccentric shaft 26 is located horizontally and rearward with respect to the axis center of the body shaft portion 261. At this time, the main feed table 22 and the differential feed table 23 remain roughly horizontal only near the top dead center, and therefore the main feed teeth 20 and the differential feed teeth 21 remain roughly horizontal only near the top dead center.

[0034] The first stage is used for basic sewing of woven fabrics such as dress shirts and rib knit fabrics such as T-shirts. When stretching or shrinking of the fabric occurs during sewing, the driving cam 30 is rotated slightly via the input device of the stepping motor 5 to slightly increase or decrease the force that feeds the fabric, thereby adjusting to eliminate the stretching or shrinking of the fabric to a certain extent. In conventional technology, the adjustment was made by loosening the screw fixing of the eccentric shaft 26, rotating it by hand, and then tightening the screw again, which required tools and time. In this embodiment, however, tools are not required and time is reduced by using, for example, a touch panel input device.

[0035] Figure 8 is a left side view showing the second stage of the feed dog tilt adjustment member and the presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. In the second stage, the cam follower 310 of the feed dog tilt adjustment lever 31 is in contact with the feed dog tilt adjustment region 300 of the drive cam 30 near the boundary of the transition region 302. This is the same state as the upper diagram of Figure 6, where the axis center of the eccentric shaft portion 260 of the eccentric shaft 26 is located rearward and downward relative to the axis center of the body shaft portion 261. At this time, the main feed table 22 and the differential feed table 23 are tilted upward at the front, and therefore the main feed dog 20 and the differential feed dog 21 are tilted upward at the front when moving up and down and back and forth on the upper surface of the needle plate 11.

[0036] The second stage is used for sewing where there are overlapping sections or thicker parts such as tape in the middle of the fabric. When the thicker parts of the fabric get stuck at the front end of the presser foot 12 and make it difficult to advance, the machine can be stopped, and the machine can be switched from the first stage to the second stage, and the front of the differential feed dog 21 can be tilted upward to increase the force that feeds the fabric.

[0037] Figure 9 is a left side view showing the third stage of the feed dog tilt adjustment member and presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. In the third stage, the cam follower 310 of the feed dog tilt adjustment lever 31 is in contact with the feed dog tilt adjustment region 300 of the drive cam 30 near the boundary of the presser foot lifting region 301. This is the same state as in the lower diagram of Figure 6, where the axis center of the eccentric shaft portion 260 of the eccentric shaft 26 is located rearward and upward relative to the axis center of the body shaft portion 261. At this time, the main feed table 22 and differential feed table 23 are tilted downward at the front, and therefore the main feed dog 20 and differential feed dog 21 are tilted downward at the front during up-and-down and back-and-forth movements.

[0038] In the third stage, the main feed dog 20 and differential feed dog 21 are significantly lowered, and their upper ends do not protrude from the upper surface of the needle plate 11 during vertical and horizontal movements, meaning they are used in a drop feed state. Furthermore, by slightly rotating the drive cam 30 from the third stage state and returning the contact point between the cam follower 310 and the drive cam 30 to the inside of the feed dog inclination adjustment region 300, the downward inclination is slightly reduced, allowing a portion of the rear end of the main feed dog 20 to protrude from the upper surface of the needle plate 11. In this state, with the vertical and horizontal movements of the main feed dog 20 and differential feed dog 21, only a portion of the rear end of the main feed dog 20 moves back and forth on the upper surface of the needle plate 11, which is used as a simple stitch pitch reduction to prevent fraying.

[0039] Figure 10 is a left side view showing the fourth stage of the feed dog tilt adjustment member and presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. In the fourth stage, the cam follower 310 of the feed dog tilt adjustment lever 31 is in contact with the middle part of the presser foot lifting region 301 of the drive cam 30, a step up from the third stage. Within the presser foot lifting region 301, similar to the third stage, the axis center of the eccentric shaft portion 260 of the eccentric shaft 26 is positioned rearward and upward relative to the axis center of the body shaft portion 261, resulting in a drop feed state.

[0040] As the process progresses from the third to the fourth stage, the pivoting end of the drive crank 40 descends, causing the press-up drive link 41 to descend and the pivoting end of the press-up drive lever 42 to descend. As a result, the engaging portion 420 of the press-up drive lever 42 comes into contact with the intermediate crank 43, and as the pivoting end of the press-up drive lever 42 descends further, the engaging portion 420 of the press-up drive lever 42 comes into contact with and presses against the intermediate crank 43, causing both to pivot downwards.

[0041] Figure 11 is a left side view showing the fifth stage of the feed dog tilt adjustment member and presser foot lifting member of the presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. In the fifth stage, the cam follower 310 of the feed dog tilt adjustment lever 31 is in contact with the presser foot lifting region 301 of the drive cam 30 near the boundary of the presser foot lifting region 301, a progression from the fourth stage. In this state, as in the third and fourth stages, the axial center of the eccentric shaft portion 260 of the eccentric shaft 26 is positioned rearward and upward relative to the axial center of the body shaft portion 261, resulting in a drop feed state.

[0042] As the process progresses from the fourth to the fifth stage, the pivoting end of the drive crank 40 descends further, and the engaging portion 420 of the press-up drive lever 42 contacts and presses against the intermediate crank 43, causing both to pivot downwards. Then, the press-up link 45, connected to another pivoting end of the intermediate crank 43, moves downwards, causing the press-up lever 46 to pivot downwards. The engaging portion 460 of the press-up lever 46 is in front of the press-up height adjustment screw 48, and as the press-up lever 46 pivots downwards, it contacts and presses against the press-up height adjustment screw 48, causing the press-up shaft crank 47 to pivot downwards and the press-up base shaft 17 to pivot. Then, the pivoting of the press-up base shaft 17 causes the press-up 12 to pivot upwards through the press-up base 13, driving the press-up mechanism. In this way, in the fifth stage, the press-up mechanism is operated in a drop-feed state.

[0043] Figure 12 is a left side view of the presser foot height sensor member and air presser foot pressure member of a presser foot lifting and feed dog tilt adjustment device for a sewing machine applied to the present invention. Another example of an embodiment of the present invention will be described below based on Figure 12. In this embodiment, the presser foot lifting and feed dog tilt adjustment device includes a presser foot height sensor member for detecting the vertical position of the presser foot. The presser foot height sensor member 6 includes a Hall sensor 60 installed on the sewing machine body 10 near the side of the presser foot base 13, and a permanent magnet 61 fixed to the middle part of the presser foot base 13. As a result, when the permanent magnet 61 moves vertically due to the vertical movement of the presser foot 12 and the presser foot base 13, the strength of the magnetic field changes and the voltage output by the Hall sensor 60 changes. Therefore, the vertical position of the presser foot 12 can be detected from the various voltage values ​​output by the Hall sensor 60 corresponding to various vertical positions of the presser foot 12.

[0044] When there are overlapping sections or thicker sections such as tape in the middle of the fabric, as the fabric is fed during sewing and reaches the front of the presser foot 12, the presser foot 12 is lifted up by the upward curve at its front end. If there is insufficient force to feed the fabric at this time, the fabric will jam at the front of the presser foot 12, making it difficult to advance. In conventional technology, in such cases, the operation is stopped, the fixing of the eccentric shaft 26 is loosened and rotated, and then fixed again to tilt the front of the differential feed dog 21 upward, thereby increasing the force to feed the fabric at the front of the presser foot 12. In this embodiment, the presser foot height sensor member 6 detects the vertical position of the presser foot 12, and by coordinating this with the control device of the stepping motor 5, the feed dog tilt adjustment member 3 can be operated without stopping the operation, tilting the front of the differential feed dog 21 upward at the thicker section of the fabric, thereby increasing the force to feed the fabric without taking time.

[0045] In this embodiment, the device for lifting the presser foot and adjusting the feed dog tilt is equipped with an air presser foot pressure member. The air presser foot pressure member 7 comprises an air cylinder 70 positioned above and behind the presser foot 12 with its axis oriented in the front-rear direction, a bracket 71 installed on the sewing machine body 10 to fix the air cylinder 70, and a bell crank 72 that transmits force by pivoting around a shaft pin (not shown) installed on the sewing machine body 10, with one pivot end contacting the tip of the shaft of the air cylinder 70 and the other pivot end contacting the upper end of the presser foot bar 14. In this embodiment, the presser foot bar spring 15 is omitted.

[0046] As a result, when the presser foot 12 rises and the presser bar 14 rises through the presser base 13, if a presser bar spring 15 is used, the amount of compression of the spring increases and the force pressing the presser foot 12 downward increases. However, in this example, since the pressure is applied by the air cylinder 70 through the bell crank 72, the force pressing the presser foot 12 downward remains constant. Therefore, when the force feeding the dough is increased by tilting the front of the differential feed teeth 21 upward in the thicker parts of the dough, the force pressing the presser foot 12 downward does not increase, allowing the dough to be fed more smoothly.

[0047] The presser foot lifting and feed dog tilt adjustment device for an overlock sewing machine described above can eliminate problems such as the need for separate drive devices for presser foot lifting and drop feed, which increases the cost and price of the sewing machine, and the inability of these drive devices to adjust the tilt of the differential feed dog. This is achieved in an overlock sewing machine that includes a needle that moves up and down, an upper looper and a lower looper that move up and down in conjunction with the needle, a needle plate installed on the sewing machine body that supports the fabric from below, a presser foot that supports the fabric from above, and a main feed dog and a differential feed dog that move up and down and back and forth.

[0048] The present invention is not limited to the embodiments described above, and those skilled in the art can implement the invention by adding various modifications to the above embodiments without departing from the spirit of the invention, and the present invention also encompasses such modifications. Furthermore, although an overlock sewing machine was used in this embodiment, the invention is not limited to this, and can be implemented in other chain stitch sewing machines such as a single-needle double chain stitch sewing machine or a safety stitch sewing machine that have a mechanism similar to that of an overlock sewing machine. [Explanation of Symbols]

[0049] 1 Sewing machine 2 Feed mechanism 3. Feed dog tilt adjustment member 4. Pressing-up member 5 Stepping motor 6. Pressing height sensor member 7. Air-pressure member 10 Sewing machine body 11 Needle Plate 12 Pressing down 13 Pressing table 14. Pressing rod 15. Retaining bar spring 16. Retaining base joint 17. Presser base shaft 18. Pressing base bearing 20 Main feed teeth 21 Differential feed dogs 22 Main feeder 23 Differential feed stage 24 Front corner piece on the sliding platform 25 Rear corner piece of the feed stand 26 Eccentric shaft 30 Driving Cam 31 Feed dog tilt adjustment lever 32 Axis pins 33 Feed tooth tilt adjustment link 34 Eccentric Axis Crank 40 Power crank 41. Press-up drive link 42 Press-up drive lever 43 Intermediate crank 44-axis pin 45. Press-up Link 46. ​​Press-up lever 47. Press-up shaft crank 48. Presser foot height adjustment screw 49. Presser foot lower dead center adjustment screw 50 Motor mounting base 60 Hall sensors 61 Permanent Magnets 70 Air Cylinder 71 Bracket 72 Bell Crank 260 Eccentric shaft part 261 Fuselage shaft section 300 Feed tooth tilt adjustment area 301 Press-up area 302 Transition region 310 CamFollowers 420 Engagement part (of the lifting drive lever) 430 (Intermediate crank) engagement part 460 (Engaging part of the lifting lever)

Claims

1. An overlock sewing machine comprising a needle that moves up and down, an upper looper and a lower looper that move back and forth in conjunction with the needle, a needle plate installed on the sewing machine body that supports the fabric from below, a presser foot that supports the fabric from above, and a main feed dog and a differential feed dog that move up and down and back and forth, characterized in that it comprises one stepping motor, a feed dog tilt adjustment member that is linked to the stepping motor, a presser foot lifting member that is linked to the stepping motor, and a control device for the stepping motor, wherein the presser foot lifting and feed dog tilt adjustment device for the overlock sewing machine is characterized in that it comprises one stepping motor, a feed dog tilt adjustment member that is linked to the stepping motor, a presser foot lifting member that is linked to the stepping motor, and a control device for the stepping motor.

2. The aforementioned device for lifting and adjusting the feed tooth inclination includes a drive crank to which the lifting member is fixed to the motor shaft of the stepping motor, a lifting drive link with one end connected to the drive crank, a lifting drive lever connected to the other end of the lifting drive link, an intermediate crank whose pivot center and pivot end are connected to the lifting drive lever and which pivots together when the engaging portion of the lifting drive lever makes contact and presses, a shaft pin inserted through a shaft hole provided in the pivot center of the intermediate crank and installed to allow the intermediate crank to pivot, and the intermediate crank not connected to the lifting drive lever. A device for adjusting the presser foot lift and feed dog tilt of an overlock sewing machine, as described in claim 1, comprising: a presser foot lift link with one end connected to another pivot end; a presser foot lift lever with the other end of the presser foot lift link connected to the pivot end, and a shaft hole provided at the pivot center that is pivotably inserted into the presser foot shaft; a presser foot lift shaft crank fixed to the presser foot shaft on the side of the presser foot lift lever; and a presser foot height adjustment screw inserted into a screw hole provided in the presser foot lift shaft crank, with the screw tip protruding and fixed, such that when the engaging portion of the presser foot lift lever contacts and presses, the presser foot lift shaft crank and the presser foot lift lever pivot together.

3. The presser foot lifting and feed dog tilting device for an overlock sewing machine according to claim 2, characterized in that the presser foot lifting and feed dog tilting device comprises a presser foot height sensor member for detecting the vertical position of the presser foot.

4. The presser foot lifting and feed dog tilt adjustment device for an overlock sewing machine according to any one of claims 1 to 3, characterized in that the device comprises a drive cam to which the feed dog tilt adjustment member is fixed to the motor shaft of the stepping motor, a feed dog tilt adjustment lever that swings in conjunction with the drive cam, a feed dog tilt adjustment link to which one end is connected to the feed dog tilt adjustment lever, and an eccentric shaft crank to which the other end of the feed dog tilt adjustment link is fixed at the pivot point to the body shaft portion of an eccentric shaft installed in the sewing machine body.

5. The presser foot lifting and feed dog tilt adjustment device for an overlock sewing machine according to claim 4, characterized in that the drive cam has a feed dog tilt adjustment region, a presser foot lifting region, and a transition region in the cam contour that is linked to the feed dog tilt adjustment lever.

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