Method for controlling length of sewing thread end of sewing machine

Abstract

The invention provides a method for controlling the length of a sewing thread end of a sewing machine, and the method comprises the steps: precisely controlling the tension of an upper thread at different stages, such as normal sewing, sewing stopping, cutting of a movable cutter and a thread shifting cutter, thread cutting of the movable cutter and a fixed cutter, thread hooking of the thread shifting cutter and the like of the sewing machine, and finally obtaining the sewing thread end with a proper length. And the upper thread cannot be separated from the needle hole of the machine needle during next sewing. By the adoption of the method for controlling the length of the sewing thread end, parameterization adjustment of the length of the sewing thread end can be achieved without cooperation of a thread loosening and bonding mechanism, and the requirement for sewing automation is better met.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a method for controlling the length of the starting thread in a sewing machine. Background Technology

[0002] Lockstitch is a strong and aesthetically pleasing stitch formed by a sewing machine interlocking the top and bottom threads on the fabric according to a specific pattern. During sewing, the bottom thread is positioned inside a rotary hook beneath the fabric. The needle pulls the top thread through the fabric, forming loops, and the bottom and top threads interlock to create a lockstitch.

[0003] Many sewing machines now feature automatic thread trimming mechanisms that cut the bobbin thread and top thread after sewing. To ensure sufficient thread length after trimming and prevent the top thread from slipping out of the needle eye when sewing resumes, thread feeding and take-up are typically performed simultaneously with thread trimming. Existing thread feeding and take-up methods transmit the action from the thread trimming drive to the thread loosening shaft, which in turn actuates the thread loosening crank, causing the thread loosening plate to move downwards and loosening the thread. Simultaneously, this actuates the take-up lever and take-up hook to complete the take-up action. Thread feeding and take-up mechanisms that achieve the above functions generally suffer from drawbacks such as complex structure, numerous parts, and cumbersome installation. Furthermore, their adjustment methods are relatively mechanical and cannot precisely adjust the length of the starting thread.

[0004] Therefore, how to accurately control the length of the starting stitch is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling the length of the starting thread in a sewing machine, which obtains starting thread with different lengths by precisely controlling the tension of the thread when the sewing machine performs different actions.

[0006] This invention provides a method for controlling the starting thread length of a sewing machine. The sewing machine includes a needle, a needle plate, a thread cutting control module, a tension control module, and a thread guiding control module. The top thread passes through the needle eye of the needle via the tension control module. The thread cutting control module includes a fixed blade and a movable blade, the movable blade being able to engage or disengage with the fixed blade. The thread guiding control module includes a movable thread guiding blade, the tip of which can reciprocate on both sides of the needle.

[0007] The method for controlling the length of the starting stitch includes the following steps:

[0008] S1. When the sewing machine is sewing normally, the tension control module controls the tension of the top thread to the first tension value c within the normal tension range. The sewing material is placed on the needle plate, and the needle causes the top thread to form a top thread loop located below the needle plate. The top thread loop and the bottom thread interweave on the sewing material to form a stitch.

[0009] S2. The sewing machine stops sewing and then performs the actions of extending the moving blade and the thread guide. The moving blade is inserted into the thread loop, and the thread guide moves so that the blade head of the thread guide exceeds the needle. During the process of the sewing machine stopping sewing and the moving blade and the thread guide extending, the tension control module controls the tension of the thread within the normal tension range.

[0010] S3. The sewing machine performs a thread-cutting action, the moving blade resets, and engages with the fixed blade to cut the bottom thread and top thread loop; during the thread-cutting process of the sewing machine, the tension control module controls the tension of the top thread to a second tension value a, which is less than the tension value within the normal tension range;

[0011] S4. The sewing machine performs the thread hooking action, the thread-pulling knife resets, and the blade of the thread-pulling knife hooks up the end of the top thread; during the thread hooking process of the sewing machine, the tension control module controls the tension of the top thread at a third tension value b, which is greater than the second tension value a and less than the tension value within the normal tension range.

[0012] Preferably, in step S2 above, during the process of the sewing machine stopping sewing and the moving knife and thread-pulling knife exiting the blade, the tension control module controls the tension of the thread at the first tension value c.

[0013] Preferably, the range of the second tension value a is: 0 ≤ a <b。

[0014] Preferably, the method further includes step S5: the sewing machine continues sewing, and the tension control module controls the tension of the thread at the first tension value c.

[0015] Preferably, the sewing machine also has a curved needle located below the needle plate.

[0016] Preferably, the thread-picking control module further includes a mounting plate fixed on the sewing machine and a drive component disposed on the mounting plate, the drive component driving the thread-picking knife to move through the thread-picking transmission assembly.

[0017] Preferably, the wire-picking control module further includes a spring plate disposed on the top of the wire-picking blade.

[0018] Preferably, the sewing machine further includes an electronic control module, which is communicatively connected to the thread cutting control module, the tension control module, and the thread pulling control module.

[0019] The advantage of this invention lies in its precise control of the thread tension at different stages of the sewing machine, including normal sewing, sewing stop, the moving and fixed blades engaging and cutting the thread, and the thread hooking blade hooking the thread. This allows for the final obtaining of a starting thread end of suitable length, ensuring that the thread will not slip out of the needle eye during the next sewing attempt. Using this method to control the starting thread end length, the parametric adjustment of the starting thread end length can be achieved without the need for a thread loosening and attaching mechanism, making it more suitable for the needs of sewing automation. Attached Figure Description

[0020] Figure 1 This is a perspective view of the sewing machine used in this invention;

[0021] Figure 2 This is a schematic diagram of the cutting and wire-drawing knife during the cutting process.

[0022] Figure 3 A schematic diagram illustrating the engagement of the moving and fixed blades during wire cutting;

[0023] Figure 4 This is a diagram illustrating how a thread-reeling tool pulls back the end of a thread.

[0024] Figure 5 This is a graph showing the changes in thread tension when a sewing machine performs different actions.

[0025] Component designation explanation:

[0026] 11. Nose

[0027] 12-frame

[0028] 2. Tension Control Module

[0029] 3. Side lines

[0030] 31. Surface thread loop

[0031] 311 Fabric edge threads

[0032] 312 Thread ends

[0033] 4. Wire guide components

[0034] 5 needles

[0035] 6. Sewing materials

[0036] 7. Curved needle

[0037] 8. Wire Cutting Control Module

[0038] 81. Cutting

[0039] 82 Fixed blade

[0040] 9. Dial-up Control Module

[0041] 91 Driver

[0042] 92 Mounting Plate

[0043] 921 Slide

[0044] 93 Springs

[0045] 94 Driven crank

[0046] 95. Turn the crank.

[0047] 951 positioning pin

[0048] 96 Spring Sheets

[0049] 97 Wire Picker

[0050] 10 lines Detailed Implementation

[0051] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0052] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] Figure 1 This is a perspective view of the sewing machine used in this invention. In the following description, it will be referred to as... Figure 1 The attached diagram serves as a reference for orientation. The length direction of the machine head 11 is defined as the left-right direction, and the wire guide 4 is located to the left of the tension control module 2. The height direction of the machine head 11 is defined as the up-down direction, and the machine head 11 is located above the machine base 12.

[0055] like Figure 1 and Figure 2As shown, the sewing machine used in this invention includes a base 12, a sewing head 11 located on top of the base 12, a needle 5 extending vertically and movable at the bottom left end of the sewing head 11, a needle plate located on top of the base 12, a thread-cutting control module 8 and a rotary hook located in the base 12 and below the needle plate, and a tension control module 2 and a thread-picking control module 9 located on the sewing head 11. The top thread 3 passes through the tension control module 2 and the thread guide 4 sequentially into the needle hole of the needle 5. The tension control module 2 provides the tension required for sewing the top thread 3. The thread-cutting control module 8 includes a fixed blade 82, a thread-cutting transmission assembly, a thread-cutting drive source, and a movable blade 81. The thread-cutting drive source can be a stepper motor, a servo motor, an electromagnet, or other drive source. The thread-cutting transmission assembly transmits the power from the thread-cutting drive source to the movable blade 81, causing the movable blade 81 to move along a preset trajectory, approaching or moving away from the fixed blade 82, engaging or disengaging with the fixed blade 82 to achieve the thread-cutting action. The thread-picking control module 9 includes a movable thread-picking knife 97, which has a cutting head for hooking the thread 3. The cutting head of the thread-picking knife 97 can move back and forth on the left and right sides of the needle 5 to achieve the thread-hooking action.

[0056] The method for controlling the length of the starting thread provided by this invention includes the following steps:

[0057] S1, such as Figure 1 and Figure 5 As shown, before time t1, the sewing machine is sewing normally. The tension control module 2 controls the tension of the top thread 3 to the first tension value c within the normal tension range. The sewing material 6 is placed on the needle plate. The needle 5 causes the top thread 3 to form a top thread loop 31 located below the needle plate. The top thread loop 31 interweaves with the bottom thread wrapped on the bobbin of the rotary hook and forms a stitch 10 on the sewing material 6.

[0058] S2, such as Figure 2 and Figure 5 As shown, the sewing machine stops sewing, and then the moving blade 81 and the thread guide blade 97 are extended. The thread cutting drive source drives the moving blade 81 to insert into the top thread loop 31, while the thread guide blade 97 moves to the left from its initial position, so that the blade head of the thread guide blade 97 passes the needle 5 and moves to the left side of the needle 5. During the process of the sewing machine stopping sewing and the moving blade 81 and the thread guide blade 97 extending, the tension control module 2 controls the tension of the top thread 3 within the normal tension range. Specifically, as shown... Figure 5 As shown, from time t1 to time t2, the sewing machine stops sewing; from time t2 to time t3, the sewing machine performs the cutting actions of the moving blade 81 and the thread guide 97. The tension values ​​within the above-mentioned normal tension range can provide the top thread 3 with the required top thread tension for sewing the fabric 6; the top thread tension when the sewing machine stops sewing and / or the top thread tension during the cutting process of the moving blade and the thread guide can be the same as or different from the first tension value c.

[0059] S3, such as Figure 3 and Figure 5 As shown, from time t3 to time t4, the sewing machine performs a thread cutting action. The thread cutting drive source drives the moving knife 81 to reset. The moving knife 81 engages with the fixed knife 82 to cut the bobbin thread and the loop 31 of the upper thread, obtaining the upper thread end 312 connected to the sewing needle 5, the fabric edge thread end 311 remaining on the fabric 6, and the bobbin thread end. During the thread cutting process of the sewing machine, the tension control module 2 controls the tension of the upper thread 3 at the second tension value a, and the second tension value a is less than the tension value within the normal tension range. That is, during the thread cutting process of the sewing machine, the tension control module 2 provides a tension less than that during normal sewing to the upper thread 3, ensuring that the moving knife 81 can smoothly hook the bobbin thread and the loop 31 of the upper thread and move towards the fixed knife 82 to complete the thread cutting. At the same time, it also ensures that the fabric edge thread end 311 remaining on the fabric 6 has an appropriate length, avoiding the thread breakage phenomenon of the stitch 10 on the fabric 6 due to the too short fabric edge thread end 311. At the same time, during this process, the thread deflecting knife 97 remains stationary and is still on the left side of the sewing needle 5.

[0060] S4. As Figure 4 and Figure 5 shown, from time t4 to time t5, the sewing machine performs a thread hooking action. The thread deflecting knife 97 resets, and the knife head of the thread deflecting knife 97 hooks the upper thread end 312. During the thread hooking process of the sewing machine, the tension control module 2 controls the tension of the upper thread 3 at the third tension value b, and the third tension value b is greater than the second tension value a and less than the tension value within the normal tension range.

[0061] Combined with Figure 4 and Figure 5 it can be known that when the thread deflecting knife 97 resets to the initial position, the starting thread end (as shown within the dotted circle in Figure 4 ) on the right side of the needle hole of the sewing needle 5 can ensure that the upper thread 3 will not come out of the needle hole of the sewing needle during the next start of sewing. If the third tension value b takes a smaller value, the supply amount of the upper thread 3 above the needle hole when the thread deflecting knife 97 hooks the thread is larger, resulting in a longer starting thread end; if the third tension value b takes a larger value, the supply amount of the upper thread 3 above the needle hole when the thread deflecting knife 97 hooks the thread is smaller, resulting in a shorter starting thread end. Therefore, by adjusting the size of the third tension value b, the length of the starting thread end can be changed.

[0062] In a preferred embodiment of the present invention, it further includes step S5: After time t5, the sewing machine continues sewing, and the tension control module 2 controls the tension of the upper thread 3 at the first tension value c.

[0063] Preferably, the value range of the second tension value a is preferably: 0 ≤ a < b. The value of the second tension value a can be 0, that is, the tension control module 2 does not clamp the thread, and the upper thread 3 is in a free state.

[0064] The tension control module 2 mentioned above can be a wire clamp. Its specific structure and working principle are existing technologies. For reference, please refer to the Chinese invention patent application with publication number CN118600660A. It will not be described in detail here.

[0065] like Figures 1-4 As shown, the sewing machine of the present invention also has a curved needle 7 disposed in the machine base 12 and located below the needle plate. In step S1 above, the curved needle 7 and the needle 5 work together to form a thread loop 31 from the top thread 3, which passes under the curved needle 7. In step S2 above, the moving blade 81 is driven by a thread cutting drive source to insert the thread loop 31 wrapped around the curved needle 7.

[0066] like Figure 2 and Figure 4 As shown, the wire-picking control module 9 also includes a mounting plate 92 fixed on the machine head 11 and a drive component 91 disposed on the mounting plate 92. The drive component 91 drives the wire-picking knife 97 to move through the wire-picking transmission component.

[0067] Specifically, the wire-picking transmission assembly includes a drive crank, a transmission connecting rod, a driven crank 94, and a rotating crank 95. The drive unit 91 can be a stepper motor, a servo motor, an electromagnet, or other rotary drive source, used to drive the drive crank to oscillate. The first end of the transmission connecting rod is hinged to the drive crank, and the second end is slidably disposed in a groove 921 on the mounting plate 92. One end of the driven crank 94 is connected to the second end of the transmission connecting rod, and the other end is hinged to the rotating crank 95. One end of the rotating crank 95 is connected to the wire-picking blade 97, and the other end is movably disposed in a through hole of a positioning pin 951, which is mounted on the mounting plate 92. The mounting plate 92 also has a fixing post, which is connected to the transmission connecting rod by a spring 93. Furthermore, the wire-picking control module 9 also includes a spring plate 96 disposed on the top of the wire-picking blade 97.

[0068] In the initial state, the second end of the transmission linkage is located at the left end of the slide groove 921, and the thread-drawing knife 97 is in the initial position on the right side of the needle 5.

[0069] In step S2 above, the driving component 91 drives the driving crank to swing, thereby causing the transmission connecting rod to move to the right. The second end of the transmission connecting rod moves to the right end of the slide groove 921, and the spring 93 is stretched. At this time, both the driven crank 94 and the rotating crank 95 swing to the left, causing the thread-pulling knife 97 to move to the left, so that the cutting head of the thread-pulling knife 97 passes past the needle 5 and moves to the left side of the needle 5.

[0070] In step S4 above, the drive component 91 stops driving. Under the elastic reset action of the spring 93, the drive crank, transmission connecting rod, driven crank 94 and rotating crank 95 are reset, driving the thread-picking knife 97 to move to the right and reset. During the reset process, the blade of the thread-picking knife 97 hooks the top thread end 312 and cooperates with the spring plate 96 to clamp the top thread end 312, leaving a starting thread end to prepare for the next starting stitch.

[0071] Those skilled in the art may also select other structural forms of wire-transfer components as needed, as long as they can achieve the function of moving the wire-transfer knife 97.

[0072] Furthermore, the sewing machine used in this invention also includes an electronic control module, which is communicatively connected to the thread cutting control module 8, the tension control module 2, and the thread picking control module 9. The electronic control module can be an existing conventional controller. The thread cutting drive source in the thread cutting control module 8, the drive component in the tension control module 2, and the drive component 91 in the thread picking control module 9 are all communicatively connected to the electronic control module, which controls the thread cutting, the tension of the top thread, and the thread hooking.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling the starting thread length of a sewing machine, characterized in that, The sewing machine includes a needle (5), a needle plate, a thread cutting control module (8), a tension control module (2), and a thread picking control module (9). The top thread (3) passes through the tension control module (2) into the needle hole of the needle (5). The thread cutting control module (8) includes a fixed blade (82) and a movable blade (81). The movable blade (81) can engage or disengage with the fixed blade (82). The thread picking control module (9) includes a movable thread picking blade (97). The blade head of the thread picking blade (97) can reciprocate on both sides of the needle (5). The method for controlling the length of the starting stitch includes the following steps: S1. When the sewing machine is sewing normally, the tension control module (2) controls the tension of the top thread (3) to the first tension value c within the normal tension range. The sewing material (6) is placed on the needle plate. The needle (5) causes the top thread (3) to form a top thread loop (31) located below the needle plate. The top thread loop (31) and the bottom thread are interwoven on the sewing material (6) to form a stitch (10). S2. The sewing machine stops sewing and then executes the cutting action of the moving blade (81) and the thread-pulling blade (97). The moving blade (81) is inserted into the thread loop (31), and the thread-pulling blade (97) moves so that the blade head of the thread-pulling blade (97) exceeds the needle (5). During the process of the sewing machine stopping sewing and the moving blade (81) and the thread-pulling blade (97) cutting, the tension control module (2) controls the tension of the thread (3) within the normal tension range. S3. The sewing machine performs a thread-cutting action. The moving blade (81) resets and engages with the fixed blade (82) to cut the bottom thread and the top thread loop (31). During the thread-cutting process of the sewing machine, the tension control module (2) controls the tension of the top thread (3) to a second tension value a, which is less than the tension value within the normal tension range. S4. The sewing machine performs the hooking action, the thread-pulling knife (97) is reset, and the blade of the thread-pulling knife (97) hooks the head of the top thread (312); during the hooking process of the sewing machine, the tension control module (2) controls the tension of the top thread (3) at a third tension value b, which is greater than the second tension value a and less than the tension value in the normal tension range.

2. The method for controlling the length of the starting stitch according to claim 1, characterized in that, In step S2 above, during the process of the sewing machine stopping sewing and the moving knife (81) and the thread-pulling knife (97) exiting the blade, the tension control module (2) controls the tension of the face thread (3) at the first tension value c.

3. The method for controlling the length of the starting stitch according to claim 1, characterized in that, The range of the second tension value 'a' is: 0 ≤ a <b。 4. The method for controlling the length of the starting stitch according to claim 1, characterized in that, It also includes step S5: the sewing machine continues sewing, and the tension control module (2) controls the tension of the face thread (3) at the first tension value c.

5. The method for controlling the length of the starting stitch according to claim 1, characterized in that, The sewing machine also has a curved needle (7) located below the needle plate.

6. The method for controlling the length of the starting stitch according to claim 1, characterized in that, The thread-picking control module (9) also includes a mounting plate (92) fixed on the sewing machine and a drive unit (91) disposed on the mounting plate (92). The drive unit (91) drives the thread-picking knife (97) to move through the thread-picking transmission assembly.

7. The method for controlling the length of the starting stitch according to claim 1, characterized in that, The wire-picking control module (9) also includes a spring plate (96) disposed on the top of the wire-picking knife (97).

8. The method for controlling the length of the starting stitch according to claim 1, characterized in that, The sewing machine also includes an electronic control module, which is communicatively connected to the thread cutting control module (8), the tension control module (2), and the thread pulling control module (9).

Images