Overlock sewing machine feed mechanism

Abstract

This invention provides a feed mechanism for an overlock sewing machine that solves the problem of the significant amount of adjustment required to change the main feed momentum and differential feed momentum compared to conventional methods. [Solution] The overlock sewing machine's feed system comprises a fabric feed mechanism 3 equipped with a main feed dog 20, differential feed dog 21, main feed table 22, differential feed table 23, feed up / down mechanism 30, main feed forward / backward mechanism 4, and differential feed forward / backward mechanism 5; a feed amount adjustment mechanism 6 equipped with a main feed amount adjustment mechanism 7 including a first stepping motor 73 and a differential feed amount adjustment mechanism 8 including a second stepping motor 83; and control devices and input devices for the first stepping motor 73 and the second stepping motor 83.

Description

Technical Field

[0001] The present invention relates to a feeding device of an overlock sewing machine. In the present invention, front and rear refer to the front and rear directions in the fabric feeding direction, left and right refer to the left and right directions when the sewing machine is viewed from the front, and up and down refer to the up and down directions of the sewing machine.

Background Art

[0002] As a feeding device of a conventional overlock sewing machine, there is known a configuration including a fabric feeding mechanism having a main feed tooth, a differential feed tooth, a main feed base, and a differential feed base, a main feed amount adjusting mechanism for adjusting a main feed momentum (also referred to as a main feed amount), which is an amount of movement in the front and rear directions of the main feed base, by an adjustment button and a double eccentric wheel, and a differential feed amount adjusting mechanism, which is a mechanism derived from the main feed amount adjusting mechanism, for separately adjusting a differential feed momentum (also referred to as a differential feed amount), which is an amount of movement in the front and rear directions of the differential feed base, by a differential adjusting lever (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In conventional technology, when sewing specifications changed and the main feed momentum and differential feed momentum of a sewing machine needed to be adjusted, the main feed momentum, which forms the basis of the stitch pitch, was first changed using the main feed amount adjustment mechanism, and then the differential feed momentum, which corresponds to the stretching of the fabric, was changed using the differential feed amount adjustment mechanism. In sewing specifications, stitch pitch is often used in increments of 1 mm or 0.5 mm. For example, when changing the stitch pitch from 2 mm to 3 mm, the main feed momentum is adjusted first. The main feed momentum changes continuously rather than discretely by operating the main feed amount adjustment mechanism, and the amount of change is measured and the operation is repeated until the desired amount is reached. For example, the desired amount is obtained by going through multiple steps such as 2 mm to 3.5 mm, 2.7 mm, 3.1 mm, etc.

[0005] Next, the differential feed momentum is adjusted. There are various purposes for adjusting the differential feed momentum, but when adjusting it to suppress fabric stretching, the first step is to roughly adjust it so that the main feed momentum and the differential feed momentum are close in value. Then, sewing is performed, the stretching state of the fabric after sewing is checked, and the adjustment is made again. By repeating this process, the desired stretching state of the fabric can be obtained. Thus, changing the main feed momentum and the differential feed momentum is a repetitive process and requires a great deal of adjustment time.

[0006] The object of the present invention is to provide a feed device for an overlock sewing machine that solves the problem of the above-mentioned difficulty in changing the main feed momentum and differential feed momentum. [Means for solving the problem]

[0007] To achieve the above objective, the invention described in claim 1 is a feed device for 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, and a presser foot that supports the fabric from above, wherein the feed device comprises a fabric feeding mechanism comprising a main feed dog, a differential feed dog, a main feed table, a differential feed table, a feed up and down mechanism, a main feed forward and backward mechanism, and a differential feed forward and backward mechanism, a feed amount adjustment mechanism comprising a main feed amount adjustment mechanism including a first stepping motor and a differential feed amount adjustment mechanism including a second stepping motor, and a control device and input device for the first stepping motor and the second stepping motor.

[0008] To achieve the above objective, the invention described in claim 2 is a feed device for an overlock sewing machine as described in claim 1, wherein the feed device is characterized in that the main feed forward / backward mechanism comprises a main feed forward / backward source eccentric, a main feed forward / backward source rod, a main feed forward / backward source link, a main feed forward / backward shaft crank, a main feed forward / backward adjustment link, a main feed forward / backward adjustment crank, a main feed forward / backward adjustment crank shaft, a feed forward / backward shaft, a main feed forward / backward crank, and a main feed table forward / backward link.

[0009] To achieve the above objective, the invention described in claim 3 is a feed device for an overlock sewing machine as described in claim 1 or claim 2, wherein the feed device is characterized in that the differential feed forward / backward mechanism comprises a differential feed forward / backward source eccentric, a differential feed forward / backward source rod, a differential feed forward / backward source link, a differential feed forward / backward shaft crank, a differential feed forward / backward adjustment link, a differential feed forward / backward adjustment crank, a differential feed forward / backward adjustment crank shaft, a differential feed forward / backward crank, and a differential feed table forward / backward link.

[0010] To achieve the above objective, the invention described in claim 4 is a feed device for an overlock sewing machine as described in claim 2, wherein the feed device is characterized in that the main feed amount adjustment mechanism comprises the first stepping motor, a main feed forward / backward adjustment lever, a first link, a first crank, and a first proximity sensor.

[0011] To achieve the above objective, the invention described in claim 5 is a feed device for an overlock sewing machine as described in claim 3, wherein the feed device is characterized in that the differential feed amount adjustment mechanism comprises the second stepping motor, a differential feed forward / backward adjustment lever, a second link, a second crank, and a second proximity sensor. [Effects of the Invention]

[0012] The feeding device of the present invention addresses the problem of the extremely time-consuming process of changing the main feed momentum and differential feed momentum in conventional technology. The feeding device comprises a dough feeding mechanism equipped with main feed teeth, differential feed teeth, main feed table, differential feed table, feed up / down mechanism, main feed forward / backward mechanism, and differential feed forward / backward mechanism; a feed amount adjustment mechanism equipped with a main feed amount adjustment mechanism including a first stepping motor and a differential feed amount adjustment mechanism including a second stepping motor; and control devices and input devices for the first and second stepping motors. This simplifies the process of changing the main feed momentum and differential feed momentum, thereby reducing the amount of adjustment required. [Brief explanation of the drawing]

[0013] [Figure 1] A perspective view from the front left 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 back, and the positive direction of the Z axis is to the up. [Figure 2] A perspective view from the left front of the feeding mechanism of a sewing machine applied to the present invention. [Figure 3] A perspective view from the right rear of the feeding mechanism of a sewing machine applied to the present invention. [Figure 4] Right side view of the main feed forward / backward mechanism and main feed amount adjustment mechanism of the sewing machine feed device applied to the present invention. [Figure 5] Left side view of the differential feed mechanism and differential feed amount adjustment mechanism of the sewing machine feed device applied to the present invention. [Modes for carrying out the invention]

[0014] An example of an embodiment of the present invention will be described below with reference to Figures 1 to 5. Figure 1 is a perspective view from the left front of a sewing machine to which the present invention is applied. 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 up. As is well known, the sewing machine 1 has a needle 12 that moves up and down, a needle plate 13 installed on the sewing machine body 10, and an upper looper 14 and a lower looper 15 that move back and forth on either side of the needle plate 13, sandwiching the needle 12, and they work together to perform sewing. The presser foot (not shown) is movable up and down and is positioned on the upper surface of the needle plate 13 in a state where it is pressed from above, and it grips the fabric being sewn by pressing it from above.

[0015] The main shaft 11 is positioned in the sewing machine body 10 so as to be rotatable in the left-right axial direction and is rotated by a drive device such as a servo motor. The rotation of the main shaft 11 is transmitted through various mechanical elements and becomes the driving force for the up-and-down movement of the needle 12 on the left, the left-right reciprocating movement of the upper looper 14 and lower looper 15, and the movement of the fabric feeding mechanism 3 of the feed device 2. The feed device 2 has a fabric feeding mechanism 3 and a feed amount adjustment mechanism 6, of which the fabric feeding mechanism 3 uses a feed up-and-down mechanism 30, a main feed forward-and-backward mechanism 4, and a differential feed forward-and-backward mechanism 5 to create the movement necessary for fabric feeding between the needle 12 and the upper looper 14 and lower looper 15.

[0016] Figure 2 is a perspective view from the front left of the feed mechanism of a sewing machine applied to the present invention, and Figure 3 is a perspective view from the rear right of the feed mechanism of a sewing machine applied to the present invention. The fabric feeding mechanism 3 is connected to and interlocks with the aforementioned up-and-down feed mechanism 30, main feed forward-and-backward mechanism 4, and differential feed forward-and-backward mechanism 5, and uses a main feed table 22, a differential feed table 23, and main feed teeth 20 and differential feed teeth 21 fixed to one front end of each to perform the necessary fabric feeding during sewing. During fabric feeding, the needle 12 and the upper looper 14 and lower looper 15 move the fabric backward by the distance of the stitch pitch each time they form a stitch. This is done when the needle 12 leaves the fabric on the upper surface of the needle plate 13 and moves upward, and the main feed teeth 20 at the rear and the differential feed teeth 21 at the front rise from below to the upper surface of the groove provided in the needle plate 13, supporting the fabric from below and pressing it with the lower surface of the presser foot while moving from front to back.

[0017] When the needle 12 descends again and pierces the fabric, the main feed teeth 20 and the differential feed teeth 21 have already retracted below the needle plate 13, and the sewing is performed while the fabric is gripped between the lower surface of the presser and the upper surface of the needle plate 13. Therefore, the main feed teeth 20 and the differential feed teeth 21 perform a periodic motion combining vertical and back-and-forth motions, and the main feed base 22 and the differential feed base 23 that fix them perform a motion that, when viewed from the side, describes, for example, an ellipse.

[0018] The feed up-and-down mechanism 30 forms the vertical motion of the main feed base 22 and the differential feed base 23. The main feed base 22 and the differential feed base 23 are plate-shaped, and with the main feed base 22 on the right side and the differential feed base 23 on the left side, they are arranged face-to-face so that they can slide relative to each other. At the rear and front of the main feed base 22 and the differential feed base 23, there are U-shaped bifurcated portions, and inside the bifurcated portions, the rectangular parallelepiped-shaped rear upper and lower feed base corner pieces 31 and the front upper and lower feed base corner pieces 32 are both arranged so that their upper and lower surfaces are guided and can slide. Axial holes penetrating in the left-right direction are formed at the centers of the rear upper and lower feed base corner pieces 31 and the front upper and lower feed base corner pieces 32.

[0019] The front upper and lower eccentric shaft portion 110 provided on the left side from the middle portion of the main shaft 11 is inserted into the axial hole of the front upper and lower feed base corner piece 32 from the right side. As the main shaft 11 rotates, the front upper and lower feed base corner piece 32 moves vertically and back-and-forth, and the main feed base 22 and the differential feed base 23 whose upper and lower surfaces are guided move vertically accordingly.

[0020] Behind the main shaft 11, the eccentric shaft 16 has an eccentric shaft portion that protrudes to the left. The shaft on the body side is inserted into a shaft hole provided in the sewing machine body 10 and fixed with a screw. The feed table rear upper and lower corner pieces 31 are inserted into the eccentric shaft portion of the eccentric shaft 16. Thus, when the main shaft 11 rotates, the feed table front upper and lower corner pieces 32 move up and down, and the front of the main feed table 22 and the differential feed table 23 move up and down. Behind the main feed table 22 and the differential feed table 23, the feed table rear upper and lower corner pieces 31 restrict the up and down movement to give an inclination. By loosening the fixing of the screw of the eccentric shaft 16, rotating it appropriately and fixing it again, the main feed table 22 and the differential feed table 23 can be in a state where they are generally horizontal only near the top dead center and inclined at other positions, or generally horizontal on the way from the front dead center to the top dead center and inclined at other positions, or generally horizontal on the way from the top dead center to the rear dead center and inclined at other positions, etc., and various inclinations can be given.

[0021] Figure 4 is a right side view of the main feed front and rear mechanism and the main feed amount adjustment mechanism of the feed device of the sewing machine applied to the present invention. The main feed front and rear mechanism 4 forms the front and rear movement of the main feed table 22. A main feed front and rear source eccentric 40 is fixed to the middle part of the lower shaft 12 on the right side of the main feed table 22, and one end of the main feed front and rear source rod 41 is inserted in a swingable manner. One end of the main feed front and rear source link 42 is swingably connected to the other end of the main feed front and rear source rod 41, and one end of the main feed front and rear shaft crank 43 is swingably connected to the other end of the main feed front and rear source link 42. The other end of the main feed front and rear shaft crank 43 is connected to the right side of the feed front and rear shaft 47 which is arranged swingably with the axial direction in the left and right direction behind the sewing machine body 10. On the left side of the feed front and rear shaft 47 and on the right side of the main feed table 22, a main feed front and rear crank 48 is connected to the feed front and rear shaft 47. One end of the main feed front and rear crank 48 is swingably connected to one end of the main feed table front and rear link 49, and the other end of the main feed table front and rear link 49 is inserted into a pin 220 installed on the side surface of the main feed table 22.

[0022] Furthermore, one end of the main feed forward / backward adjustment link 44 is pivotably connected to the connection between the main feed forward / backward source rod 41 and the main feed forward / backward source link 42. The main feed forward / backward adjustment crank 45 has its pivot center connected to the main feed forward / backward adjustment crankshaft 46, which is positioned on the sewing machine body 10 so as to be pivotable with its axial direction from left to right, and one end of the crank is pivotably connected to the other end of the main feed forward / backward adjustment link 44. Therefore, the position of the other end of the main feed forward / backward adjustment link 44 is determined by rotating and fixing the main feed forward / backward adjustment crankshaft 46 to a specific phase.

[0023] In this state, when the lower shaft 12 rotates, the main feed front / rear source eccentric 40 rotates, the main feed front / rear source rod 41 moves with its movement restricted by the main feed front / rear adjustment link 44, the main feed front / rear source link 42 which is also restricted in its movement moves, causing the main feed front / rear axis crank 43 to swing, and the feed front / rear axis 47 to swing. Then the main feed front / rear crank 48 swings, causing the main feed table front / rear link 49 to move back and forth, and the main feed table 22 to move back and forth via the pin 220.

[0024] The main feed momentum represents the amount of movement of the main feed table 22 in the forward and backward direction. However, as mentioned above, the main feed table 22 performs a periodic motion that combines up-and-down and forward-and-backward movement while changing its inclination state during a single dough feeding operation, due to the up-and-down feed mechanism 30 and the forward-and-backward main feed mechanism 4, making it difficult to capture precisely. Therefore, the main feed momentum is conventionally expressed as the distance that the working end of the forward-and-backward crank 48, i.e., the connection point with the forward-and-backward link 49 of the main feed table, moves forward and backward due to the oscillation of the crank 48, and this is the meaning used in this embodiment as well.

[0025] As described above, by changing the phase of the main feed forward / backward adjustment crankshaft 46, the motion of the main feed forward / backward source rod 41 and the main feed forward / backward source link 42 changes via the main feed forward / backward adjustment link 44, the amount of oscillation of the main feed forward / backward axis crank 43 and the feed forward / backward axis 47 changes, the amount of oscillation of the main feed forward / backward crank 48 changes, the forward / backward motion of the main feed table forward / backward link 49 changes, and the main feed momentum changes. In other words, it is possible to adjust the main feed momentum by increasing or decreasing it.

[0026] Figure 5 is a left side view of the differential feed forward / backward mechanism and differential feed amount adjustment mechanism of the sewing machine feed device applied to the present invention. The differential feed forward / backward mechanism 5 forms the forward / backward motion of the differential feed table 23. A differential feed forward / backward source eccentric 50 is fixed to the middle of the lower shaft 12 on the left side of the differential feed table 23, and one end of the differential feed forward / backward source rod 51 is pivotably inserted through it. One end of the differential feed forward / backward source link 52 is pivotably connected to the other end of the differential feed forward / backward source rod 51, and one end of the differential feed forward / backward axis crank 53 is pivotably connected to the other end of the differential feed forward / backward source link 52, and the shaft hole provided in the middle of the differential feed forward / backward axis crank 53 is pivotably inserted to the left of the aforementioned feed forward / backward axis 47 located at the rear of the sewing machine body 10. The differential feed forward / backward axis crank 53 and the feed forward / backward axis 47 are not connected. One end of the differential feed front / rear crank section 58, which is the other end of the differential feed front / rear axis crank 53, is pivotably connected to the differential feed front / rear link 59, and the other end of the differential feed front / rear link 59 is inserted through a pin 230 installed on the left side of the differential feed table 23.

[0027] Furthermore, one end of a differential feed front / rear adjustment link 54 is pivotably connected to the connection between the differential feed front / rear source rod 51 and the differential feed front / rear source link 52. The differential feed front / rear adjustment crank 55 has its pivot center connected to a differential feed front / rear adjustment crankshaft 56, which is pivotably positioned on the sewing machine body 10 with its axial direction from left to right, and one end of the crank is pivotably connected to the other end of the differential feed front / rear adjustment link 54. Therefore, the differential feed front / rear adjustment crank 55 determines the position of the other end of the differential feed front / rear adjustment link 54 by rotating and fixing the differential feed front / rear adjustment crankshaft 56 to a specific phase.

[0028] In this state, when the lower shaft 12 rotates, the differential feed front / rear source eccentric 50 rotates, the differential feed front / rear source rod 51 moves with its movement restricted by the differential feed front / rear adjustment link 54, the differential feed front / rear source link 52, whose movement is also restricted, moves, causing the differential feed front / rear shaft crank 53 to swing, the differential feed front / rear crank section 58 to swing, the differential feed front / rear link 59 to move back and forth, and the differential feed table 23 to move back and forth via the pin 230.

[0029] The differential feed momentum represents the amount of movement of the differential feed table 23 in the forward and backward directions. However, as mentioned above, the differential feed table 23 performs a periodic motion that combines up-and-down and forward-and-backward movement while changing its inclination state during a single dough feeding operation, due to the up-and-down feed mechanism 30 and the forward-and-backward differential feed mechanism 5, making it difficult to capture precisely. Therefore, the differential feed momentum is conventionally expressed as the distance that the operating end of the forward-and-backward crank section 58, i.e., the connection point with the forward-and-backward link 59 of the differential feed table, moves forward and backward due to the oscillation of the crank section 58, and this is the meaning used in this embodiment as well.

[0030] As described above, by changing the phase of the differential feed forward / backward adjustment crankshaft 56, the motion of the differential feed forward / backward source rod 51 and the differential feed forward / backward source link 52 changes via the differential feed forward / backward adjustment link 54, which changes the amount of oscillation of the differential feed forward / backward axis crank 53, which changes the amount of oscillation of the differential feed forward / backward crank section 58, which changes the forward / backward motion of the differential feed table forward / backward link 59, and thus changes the differential feed momentum. In other words, it is possible to adjust the differential feed momentum by increasing or decreasing it. As mentioned above, the differential feed forward / backward axis crank 53 and the feed forward / backward axis 47 are not connected, and the differential feed forward / backward axis crank 53 and the main feed forward / backward axis crank 43 do not interlock, so the main feed momentum and the differential feed momentum do not interlock. This means that even if the main feed momentum is changed, the differential feed momentum does not change, and even if the differential feed momentum is changed, the main feed momentum does not change.

[0031] The main feed amount adjustment mechanism 7 shown in Figure 4 adjusts the main feed momentum by changing the phase of the main feed forward / backward adjustment crankshaft 46. One end of the main feed forward / backward adjustment lever 70 is fixed to the right end of the main feed forward / backward adjustment crankshaft 46. One end of the first link 71 is pivotably connected to the other end of the main feed forward / backward adjustment lever 70. The first crank 72 is pivotably connected to the other end of the first link 71. The other end of the first crank 72 is fixed to the shaft of the first stepping motor 73. As a result, when the first stepping motor 73 is driven, the first crank 72 rotates, causing the main feed forward / backward adjustment lever 70 to pivot via the first link 71, and changing the phase of the main feed forward / backward adjustment crankshaft 46. In this embodiment, the first stepping motor 73 is installed on the right side of the rear of the sewing machine body 10, and the space to the right of the sewing machine 1 is secured as in conventional technology, so as not to interfere with placing fabric or items before sewing.

[0032] A first proximity sensor 74 is installed a short distance to the side of the first crank 72 to detect the first detection unit 720 provided on the first crank 72. The first proximity sensor 74 can be an inductive proximity sensor, a magnetic proximity sensor, or the like. This determines the origin position for driving the first stepping motor 73. An encoder or the like may also be used for this purpose.

[0033] The differential feed amount adjustment mechanism 8 shown in Figure 5 adjusts the differential feed momentum by changing the phase of the differential feed forward / backward adjustment crankshaft 56. One end of the differential feed forward / backward adjustment lever 80 is fixed to the right end of the differential feed forward / backward adjustment crankshaft 56. One end of the second link 81 is pivotably connected to the other end of the differential feed forward / backward adjustment lever 80. The second crank 82 is pivotably connected to the other end of the second link 81. The other end of the second crank 82 is fixed to the shaft of the second stepping motor 83. As a result, when the second stepping motor 83 is driven, the second crank 82 rotates, causing the differential feed forward / backward adjustment lever 80 to pivot via the second link 81, and changing the phase of the differential feed forward / backward adjustment crankshaft 56. In this embodiment, the second stepping motor 83 is installed on the left side of the rear side of the sewing machine body 10, and the space to the left of the sewing machine 1 is secured as in conventional technology, so as not to interfere with placing fabric or items before sewing.

[0034] A second proximity sensor 84 is installed a short distance to the side of the second crank 82 to detect the second detection unit 820 provided on the second crank 82. The second proximity sensor 84 can be an inductive proximity sensor, a magnetic proximity sensor, or the like. This determines the origin position for driving the second stepping motor 83. An encoder or the like may also be used for this purpose.

[0035] As described above, the main feed rate adjustment mechanism 7 and the differential feed rate adjustment mechanism 8 adjust the main feed momentum and differential feed momentum by driving the first stepping motor 73 and the second stepping motor 83. The first stepping motor 73 and the second stepping motor 83 can be individually changed through a control device (not shown) that controls their operating angle and an input device (not shown) such as a controller or touch panel, thereby setting the parameters of the main feed momentum and differential feed momentum according to the operating angle. This does not require repeated operations such as measuring how much the main feed momentum has actually changed and repeating the operation until the desired amount is reached, as in conventional technology. Furthermore, once the parameters are set and recorded according to the sewing conditions, even if the sewing conditions are changed afterward, they can be easily set again based on the record when restoring to the original sewing conditions.

[0036] Furthermore, in systems equipped with a first stepping motor and a second stepping motor, the operation of the main feed momentum and differential feed momentum for the purpose of preventing fraying can be performed with reduced effort. Fraying refers to the unraveling of the entire stitch after some threads come loose from the end of the stitch for some reason, and preventing fraying is a treatment to prevent this. In chain stitch sewing machines, fraying is sometimes prevented by stopping the machine a little before the end of sewing, changing the main feed momentum and differential feed momentum to the minimum, and sewing several to more than ten times to create a very fine stitch pitch, which requires a dedicated device including drive equipment and switches. With the feed device of the present invention, as described above, the main feed momentum and differential feed momentum can be adjusted through the control device and input device, and it is also possible to minimize the main feed momentum and differential feed momentum for preventing fraying, so a separate dedicated device is not required.

[0037] Furthermore, the control devices for the first stepping motor 73 and the second stepping motor 83 may be linked with the control device for operating the sewing machine 1 to change the main feed momentum and differential feed momentum during sewing. This allows for sewing processes where the stitch pitch changes midway through sewing a single piece of fabric, such as changing the main feed momentum and differential feed momentum to alter the stitch pitch after the fabric has been sewn and advanced a predetermined distance, and then returning to the original setting after advancing a certain distance. This enables sewing processes such as improving stitch strength by making the stitch pitch finer only around thicker sections in the fabric, or creating pseudo-pleats by reducing only the main feed momentum without changing the differential feed momentum during sewing to feed extra fabric into the presser foot.

[0038] As described above, the feed device for the overlock sewing machine includes a fabric feeding mechanism comprising a main feed dog, differential feed dog, main feed table, differential feed table, feed up / down mechanism, main feed forward / backward mechanism, and differential feed forward / backward mechanism; a feed amount adjustment mechanism comprising a main feed amount adjustment mechanism including a first stepping motor and a differential feed amount adjustment mechanism including a second stepping motor; and control devices and input devices for the first and second stepping motors. This eliminates the problem that changing the main feed momentum and differential feed momentum is extremely time-consuming.

[0039] As mentioned above, it is also possible to perform sewing processes such as stopping the sewing machine just before the end of sewing and changing the main feed momentum and differential feed momentum to the minimum to create a very fine stitch pitch and sewing several to more than ten times to prevent fraying, or when there is a thick step in the middle of the fabric, making the stitch pitch finer only around the step to improve the strength of the stitch, or sewing processes that reduce only the main feed momentum without changing the differential feed momentum during sewing to feed extra fabric into the presser foot and create a pseudo-fold.

[0040] 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]

[0041] 1 Sewing machine 2. Feed device 3. Dough feeding mechanism 4. Main feed mechanism 5. Differential feed mechanism 6 Feed amount adjustment mechanism 7. Main feed amount adjustment mechanism 8. Differential feed amount adjustment mechanism 10 Sewing machine body 11 Spindle 12 needles 13 Needle Plate 14 Upper Looper 15 Lower Looper 16 Eccentric shaft 20 Main feed teeth 21 Differential feed dogs 22 Main feeder 23 Differential feed stage 30 Feed Up / Down Mechanism 31 Rear upper and lower corner pieces of the feed stand 32 Front upper and lower corner pieces of the feed stand 33 Front upper and lower rods of the feed platform 34 Front vertical axis crank of the feed platform 35 Front vertical axis of the feed table 36 Front up and down crank on the feed platform 37 pins 40 Main feed front and rear source eccentric 41 Main feed front and rear source rods 42 Main feed source links 43 Main feed front and rear axis crank 44 Main feed forward / backward adjustment link 45 Main feed forward / backward adjustment crank 46 Main feed forward / backward adjustment crankshaft 47 Feed axis (forward and backward) 48 Main feed front and rear crank 49 Main feeder front and rear links 50 Differential feed forward / backward source eccentric 51 Differential feed front and rear source rods 52 Differential feed front and rear source link 53 Differential feed front and rear axis crank 54 Differential feed front and rear adjustment link 55 Differential Feed Front and Rear Adjustment Crank 56 Differential feed forward / backward adjustment crankshaft 58 Differential feed front and rear crank section 59 Differential feed front and rear linkage 70 Main feed forward / backward adjustment lever 71 Link 1 72 First Crank 73 First stepping motor 74. First proximity sensor 80 Differential Feed Front / Rear Adjustment Lever 81 Second Link 82 Second crank 83. Second stepping motor 84. Second proximity sensor 110 Front upper and lower eccentric shaft section of the feed table 220 pins 230 pins 720 First detection unit 820 Second detection unit

Claims

1. A feed device for 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, and a presser foot that supports the fabric from above, wherein the feed device comprises a fabric feeding mechanism comprising a main feed dog, a differential feed dog, a main feed table, a differential feed table, a feed up and down mechanism, a main feed forward and backward mechanism, and a differential feed forward and backward mechanism, a feed amount adjustment mechanism comprising a main feed amount adjustment mechanism including a first stepping motor and a differential feed amount adjustment mechanism including a second stepping motor, and a control device and input device for the first stepping motor and the second stepping motor.

2. The feed device for an overlock sewing machine according to claim 1, characterized in that the main feed forward / backward mechanism comprises a main feed forward / backward source eccentric, a main feed forward / backward source rod, a main feed forward / backward source link, a main feed forward / backward shaft crank, a main feed forward / backward adjustment link, a main feed forward / backward adjustment crank, a main feed forward / backward adjustment crank shaft, a feed forward / backward shaft, a main feed forward / backward crank, and a main feed table forward / backward link.

3. The feed device for an overlock sewing machine according to claim 1 or 2, characterized in that the differential feed forward / backward mechanism comprises a differential feed forward / backward source eccentric, a differential feed forward / backward source rod, a differential feed forward / backward source link, a differential feed forward / backward shaft crank, a differential feed forward / backward adjustment link, a differential feed forward / backward adjustment crank, a differential feed forward / backward adjustment crank shaft, a differential feed forward / backward crank, and a differential feed table forward / backward link.

4. The feed device for an overlock sewing machine according to claim 2, characterized in that the main feed amount adjustment mechanism comprises the first stepping motor, a main feed forward / backward adjustment lever, a first link, a first crank, and a first proximity sensor.

5. The feed device for an overlock sewing machine according to claim 3, characterized in that the differential feed amount adjustment mechanism comprises the second stepping motor, a differential feed forward / backward adjustment lever, a second link, a second crank, and a second proximity sensor.

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