A long-arm thick material sewing device and its design method

Abstract

The present invention provides a long-arm thick material suturing device and its design method, belonging to the technical field of three-dimensional suturing of carbon / carbon composite materials. The device includes a thread picking mechanism for maintaining the tension of the suture thread; a material piercing mechanism for inserting the suture thread into the carbon / carbon composite material; a thread hooking mechanism for feeding the bottom thread and hooking the suture thread fed by the piercing mechanism to form a thread loop; and a needle holding mechanism for protecting the suture needle, preventing it from bending or even breaking when subjected to significant resistance. The present invention specifically sews conical, thick carbon / carbon composite materials with a thickness of 50 mm or more, improving their mechanical properties and providing a corresponding theoretical basis for related research. It improves the automation level of suturing technology, expands the application range of three-dimensional suturing of carbon / carbon composite materials, and can effectively improve the processing efficiency of carbon / carbon composite preforms, reduce costs, and improve economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of three-dimensional stitching of carbon / carbon composite materials, and in particular relates to a long-arm thick material stitching device and a design method thereof. Background Art

[0002] Carbon / carbon composites are carbon-matrix composites reinforced with carbon fibers and their fabrics. They have the advantages of low density, high strength, high specific modulus, high thermal conductivity, low expansion coefficient, good friction performance, good thermal shock resistance, and high dimensional stability. They are one of the few alternative materials currently used above 1650°C, with a maximum theoretical temperature of up to 2600°C. Therefore, they are considered to be one of the most promising high-temperature materials.

[0003] The maximum thickness of carbon / carbon stitched composite materials available on the market is 30 mm. For stitching between layers of composite materials with such a small thickness, ordinary industrial stitching equipment can be used for stitching.

[0004] The production of thick three-dimensional stitched carbon / carbon composite preforms is not possible with existing single-sided stitching devices controlled by six-degree-of-freedom industrial robots due to the constraints of the fabric stitching thickness and the characteristics of the carbon fiber stitching thread itself.

[0005] ALTIN ​​Nahtechnik of Germany has developed a high-precision single-sided stitching device. Using a CNC robot to control the stitching unit, it can continuously stitch composite materials. However, this device still has limitations. Due to the limitations of the molding process, the maximum stitching thickness is only 30mm. The Beijing Aeronautical Manufacturing Engineering Research Institute of AVIC, in collaboration with domestic companies, has developed my country's first three-dimensional stitching device for composite materials. However, its maximum stitching thickness is also limited to 30mm. Because it uses a single-sided stitching method, it is difficult to effectively stitch thicker carbon / carbon composite materials.

[0006] Therefore, most of the carbon / carbon composite material stitching technology is still at the manual or semi-manual and semi-mechanical stage, which cannot meet the needs of industrial applications of carbon / carbon composite materials. Domestically, the stitching of 70mm thick laminated woven carbon cloth is still at the purely manual stage, which seriously limits the scope of use of carbon / carbon composite materials. Summary of the Invention

[0007] The problem to be solved by the present invention is to provide a long-arm thick material sewing device and a design method thereof.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a long-arm thick material suturing device, including a thread picking mechanism for maintaining the tension of the suture thread; a material piercing mechanism for piercing the suture thread into the carbon / carbon composite material; a thread hooking mechanism for feeding the bottom thread and hooking the suture thread fed by the material piercing mechanism to form a thread loop; a needle holding mechanism for protecting the suture needle to prevent the suture needle from bending or even breaking when encountering large resistance.

[0009] The pricking mechanism includes a flywheel crank, which is hinged to the slider connecting rod to realize the conversion of linear motion; the flywheel crank is disc-shaped and is axially installed on the main shaft; the slider connecting rod is hinged to the needle bar slider, so that the needle bar slider can slide back and forth, thereby realizing the normal operation of the pricking mechanism; the needle bar slider drives the needle bar to move up and down, and a suture needle is installed at the bottom end of the needle bar.

[0010] The thread take-up mechanism includes a thread take-up rod, which is L-shaped and installed on the flywheel crank. The long side of the thread take-up rod is the thread take-up rod I, which extends outward and has a thread passing hole at the end. The short side of the thread take-up rod is the thread take-up rod II, and the end of the thread take-up rod II is connected to the flywheel crank through the thread take-up crank; a thread take-up rocker is hinged at the bend of the thread take-up rod.

[0011] The needle holding mechanism includes a needle holding block, which is installed at the bottom end of the presser foot rod. The suture needle passes through the needle holding block to assist in completing the reciprocating motion of the suture needle; a presser foot slider is installed on the presser foot rod.

[0012] The thread hooking mechanism includes a disc cam and a cylindrical cam. The disc cam and cylindrical cam combine to achieve a combination of reciprocating swing and linear motion of the hook. Both the disc cam and cylindrical cam are mounted on a main shaft. The disc cam drives push rod I, which drives a connecting rod to rotate the hook swing arm. The hook swing arm then rotates the hook shaft, on which the hook is mounted, achieving rotation of the hook. The cylindrical cam drives push rod II, causing it to perform linear reciprocating motion. Push rod II is connected to a guide rail. The linear reciprocating motion of push rod II drives the linear motion of the guide rail, which in turn drives the hook to achieve linear reciprocating motion.

[0013] Furthermore, the thread picking mechanism, material piercing mechanism, needle holding mechanism and thread hooking mechanism are all installed on the body bracket, and a flange interface is installed on the body bracket, and the body bracket is connected and fixed to the industrial sewing machine through the flange interface.

[0014] Furthermore, a thread hooking mechanism shell is provided at the bottom of the body bracket. The cross-section of the thread hooking mechanism shell is a hollow hexagon, including a front cover, a hook upper cover, a cavity upper shell and a cavity base shell. The cavity upper shell and the cavity base shell are fastened together and fixed by a connecting piece to form a thread hooking mechanism cavity. The front cover is fixed to the front end of the thread hooking mechanism cavity, and the hook upper cover is installed on the top of the cavity upper shell.

[0015] Furthermore, the presser foot slider is hinged with a hinged plate, which is hinged to the presser foot wrench via connecting rod I. The hinged plate is hinged to the eccentric shaft crank via connecting rod II. The eccentric shaft crank is connected to connecting rod II via an eccentric shaft and is mounted on one side of the flywheel crank. The presser foot wrench is used to adjust the height of the needle gripper's presser foot to accommodate fabric thicknesses and sewing requirements. The eccentric shaft crank rotates the eccentric shaft through rotational motion, pushing the presser foot slider to complete the work.

[0016] Furthermore, a gasket is provided between the cylindrical cam and the disc cam.

[0017] Furthermore, the main shaft is driven by a motor.

[0018] Furthermore, a pin is installed at the end of the guide rail, and the pin cooperates with the hook groove of the hook, so that the linear reciprocating motion of the push rod II drives the linear reciprocating motion of the hook.

[0019] The present invention also provides a design method for a long-arm thick material sewing device, comprising the following steps:

[0020] S1. Determination of the piercing mechanism: Set the thickness of the carbon / carbon composite material to be sutured to According to the distance from the suture needle hole to the bottom surface of the carbon / carbon composite material when the suture needle reaches the lowest end and the fixed distance from the suture needle hole to the suture needle tip, the distance from the suture needle tip to the bottom surface of the carbon / carbon composite material is taken. When the suture needle rises to the highest point, the distance between the suture needle tip and the upper surface of the carbon / carbon composite material is , and finally determine the motion stroke of the suture needle to be , and then determine the working length of the flywheel crank , eccentricity b, slider connecting rod length .

[0021] S2. Determination of the needle holding mechanism:

[0022] The instability condition for the suture needle shaft to be stable is:

[0023] (11)

[0024] In formula (11), is the working length of the suture needle, is the elastic modulus, is the moment of inertia of the section, is the length factor;

[0025] Calculation of the maximum resistance of a suture needle penetrating a cone-shaped carbon / carbon composite material with different thicknesses , in the state without the needle holding mechanism, the working safety factor of the suture needle is:

[0026] (12)

[0027] The value of n in formula (12) is combined with the stability safety factor In contrast, the value of n is less than When suturing, it is necessary to design a needle holding mechanism to increase the working safety factor of the suture needle to maintain the stable operation of the suture needle.

[0028] S3. Determination of the thread taking-up mechanism: The working characteristics of the thread taking-up mechanism depend on the up and down movement of the thread taking-up rod through the thread hole. When the suture needle descends, the thread taking-up rod of the thread taking-up mechanism also needs to descend to supply thread to the suture needle; then when the hook hooks the upper thread, the thread taking-up rod needs to continue to move downward to supply thread for the formation of the thread loop; when the thread loop is formed and the suture needle moves upward, the thread taking-up rod needs to remove the upper thread from the hook hook to tighten the stitches formed in the carbon / carbon composite material to form a firm stitch, and draw out the upper thread from the thread ball to prepare for the formation of the next stitch.

[0029] In order to coordinate the actions of the material-piercing mechanism and the thread-hooking mechanism, it is necessary to plan the trajectory of the thread hole on the thread-taking rod of the thread-taking mechanism.

[0030] The present invention adopts the method of combining graphic method and SOLIDWORDS simulation to select the appropriate length of thread take-up rod I and the angle between thread take-up rod I and thread take-up rod II. Import the parameters into SOLIDWORDS for modeling and select different points on the thread take-up lever I for simulation to obtain the trajectory formed by the motion trajectory of some points on the thread take-up lever I.

[0031] S4. Determination of the hooking mechanism:

[0032] S41. Calculation of disc cam mechanism:

[0033] Set the length of push rod I, the length of connecting rod, the length of hook swing arm and the hook rotation angle, calculate the relationship between the hook rotation angle and the disc cam profile, and obtain the disc cam profile;

[0034] S42. Calculation of cylindrical cam mechanism:

[0035] Because the chain sewing method is adopted, it can be seen that the crochet hook first hooks the thread loop from one side of the suture needle, and then moves to the other side of the suture needle. As the suture needle falls again, it falls between the bottom line and the crochet hook, thereby completing the locking action.

[0036] The hook moves horizontally, and the gap between the hook and the suture needle is set to s, the hook thickness is m, and the suture needle diameter is d. Then the moving stroke a of the hook is:

[0037]

[0038] The profile of the cylindrical cam is calculated based on the moving stroke a of the hook.

[0039] Furthermore, in step S1, kinematic analysis calculation is performed on the determined piercing mechanism:

[0040] With the rotation center of the flywheel crank as the center o, the length of the flywheel crank as the radius L1, the horizontal direction as the x-axis, and the vertical direction as the y-axis, a rectangular coordinate system is established. The eccentricity is known to be b, and the angle between the horizontal direction and the vertical axis of point A is , flywheel crank angle , flywheel crank angular velocity , slider connecting rod length , slider connecting rod angle , slider-connecting rod angular velocity , establish the displacement at the needle bar ,speed and acceleration equation.

[0041] S11. Displacement calculation:

[0042] According to the vector composition theorem, the equation can be listed:

[0043] (1)

[0044] Converted to plural form, we get:

[0045] (2)

[0046] in , i is an imaginary unit;

[0047] Expanding formula (2) and taking the real and imaginary parts respectively yields:

[0048] (3)

[0049] (4);

[0050] S12, speed calculation:

[0051] Taking the time derivative of Equation (2) we can get the complex form of the velocity vector equation of the needle rod, which is:

[0052] (5)

[0053] Where, , ;

[0054] Multiply both sides of formula (5) by , expand and take the real part, and we get:

[0055] (6)

[0056] Taking the imaginary part, we get:

[0057] (7);

[0058] S13, acceleration calculation:

[0059] By taking the time derivative of Equation (5), we can obtain the complex form of the velocity vector equation of the needle rod, which is:

[0060] (8)

[0061] In formula (8), is the acceleration of the flywheel crank 21, is the acceleration of the slider connecting rod 22;

[0062] Multiply both sides of formula (8) by , expand and take the real part, and we get:

[0063] (9)

[0064] In formula (9), is the acceleration at the needle rod;

[0065] Taking the imaginary part, we get:

[0066] (10).

[0067] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0068] This invention designs a long-arm double-sided stitching device for thick materials. It features a flange interface on the top of the device for connection to an industrial robot, forming a double-sided stitching robot system. Compared to traditional industrial sewing machines, this device primarily consists of three mechanisms: a thread hooking mechanism, a material piercing mechanism, and a thread take-up mechanism. It can smoothly stitch thick carbon / carbon composite materials and maximize the stitching area of ​​tapered carbon / carbon composite materials.

[0069] The present invention uses a double-sided stitching method to sew carbon / carbon composite materials. Chain stitching reduces bending of the suture thread (carbon fiber yarn), facilitating the stitching process. This method effectively improves the interlayer performance of the carbon / carbon composite material. Furthermore, the stitching locks tightly, and the stress generated by the chain stitches is localized on the surface of the material being stitched, without affecting the internal interlayer performance of the carbon / carbon composite material.

[0070] The present invention specifically stitches tapered carbon / carbon composite materials with a thickness of more than 50 mm to improve their mechanical properties and provide a corresponding theoretical basis for related research.

[0071] The present invention improves the automation level of stitching technology, expands the application range of three-dimensional stitched carbon / carbon composite materials, can effectively improve the processing efficiency of carbon / carbon composite material preforms, reduce costs, and improve economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The present invention will be described in detail below with reference to the accompanying drawings and in combination with examples, and the advantages and implementation modes of the present invention will become more apparent. The contents shown in the accompanying drawings are only used to illustrate the present invention and do not constitute any limitation to the present invention. In the accompanying drawings:

[0073] Figure 1 It is a structural schematic diagram of the present invention.

[0074] Figure 2 It is a structural schematic diagram of the line hooking mechanism housing of the present invention.

[0075] Figure 3 It is a structural schematic diagram of the thread taking-up mechanism and the needle holding mechanism of the present invention.

[0076] Figure 4 It is a structural schematic diagram of the material piercing mechanism and the needle holding mechanism of the present invention.

[0077] Figure 5 It is a structural schematic diagram of the line hooking mechanism of the present invention.

[0078] Figure 6 It is a structural schematic diagram of the disc cam of the present invention.

[0079] Figure 7 It is a structural schematic diagram of the cylindrical cam of the present invention.

[0080] Figure 8 It is a structural schematic diagram of a crochet hook of the present invention.

[0081] Figure 9 It is the kinematic model of the piercing mechanism of the present invention.

[0082] Figure 10 It is a motion diagram of the needle holding mechanism of the present invention.

[0083] Figure 11 It is the kinematic model of the thread taking-up mechanism of the present invention.

[0084] Figure 12 It is the motion trajectory of the upper part of the thread take-up lever I of the present invention.

[0085] Figure 13 It is a schematic diagram of the motion of the disc cam mechanism of the present invention.

[0086] Figure 14 It is the theoretical profile of the disc cam of the present invention.

[0087] Figure 15 It is the actual profile of the disc cam of the present invention.

[0088] Figure 16 It is a schematic diagram of the linear displacement of the crochet hook of the present invention.

[0089] Figure 17 It is the profile of the cylindrical cam of the present invention.

[0090] In the picture:

[0091] 1. Thread picking mechanism; 2. Material piercing mechanism; 3. Needle holding mechanism; 4. Thread hooking mechanism; 5. Machine body bracket; 6. Flange interface; 7. Thread hooking mechanism housing; 8. Spindle; 9. Motor; 10. Reducer;

[0092] 11. Thread take-up lever; 12. Thread hole; 13. Thread take-up crank; 14. Thread take-up rocker; 111. Thread take-up lever I; 112. Thread take-up lever II;

[0093] 21. Flywheel crank; 22. Slider connecting rod; 23. Needle bar slider; 24. Needle bar; 25. Suture needle;

[0094] 31. Needle holding block; 32. Presser foot rod; 33. Presser foot slider; 34. Hinge plate; 35. Presser foot wrench; 36. Connecting rod I; 37. Connecting rod II; 38. Eccentric shaft crank; 39. Eccentric shaft;

[0095] 41. Disc cam; 42. Cylindrical cam; 43. Hook; 44. Push rod I; 45. Connecting rod; 46. Hook swing arm; 47. Hook shaft; 48. Push rod II; 49. Push rod support platform; 410. Guide rail; 411. Hook groove;

[0096] 71. Front cover; 72. Crochet upper cover; 73. Cavity upper shell; 74. Cavity base shell. DETAILED DESCRIPTION

[0097] like Figures 1 to 17As shown, the present invention is a long-arm thick material suturing device, comprising a thread picking mechanism 1 for maintaining the tension of the suture thread; a material piercing mechanism 2 for piercing the suture thread into the carbon / carbon composite material; a thread hooking mechanism 4 for feeding the bottom thread and hooking the suture thread fed by the material piercing mechanism to form a thread loop; and a needle holding mechanism 3 for protecting the suture needle to prevent the suture needle from bending or even breaking when encountering large resistance.

[0098] The thread taking-up mechanism 1 , the material piercing mechanism 2 , the needle holding mechanism 3 and the thread hooking mechanism 4 are all installed on the body bracket 5 , and a flange interface 6 is installed on the body bracket 5 . The body bracket 5 is connected and fixed to the industrial sewing machine through the flange interface 6 .

[0099] A thread hooking mechanism shell 7 is provided at the bottom of the body bracket 5. The cross-section of the thread hooking mechanism shell 7 is a hollow hexagon, including a front cover 71, a hook upper cover 72, a cavity upper shell 73 and a cavity base shell 74. The cavity upper shell 73 and the cavity base shell 74 are fastened together and fixed by connecting parts to form a thread hooking mechanism cavity. The front cover 71 is fixed to the front end of the thread hooking mechanism cavity, and the hook upper cover 72 is installed on the top of the cavity upper shell 73.

[0100] The puncture mechanism 2 includes a flywheel crank 21, which is connected to the slider connecting rod 22 through a flange to realize the conversion of linear motion; the flywheel crank 21 is disc-shaped, axially mounted on the bearing, and connected to the main shaft 8, and the slider connecting rod 22 is connected to the needle bar slider 23 through a flange, so that the needle bar slider 23 can slide back and forth, thereby realizing the normal operation of the puncture mechanism 2, and the needle bar slider 23 and the body bracket 5 are connected through the slider guide wheel, and the slider guide wheel is fixed on the body bracket 5, and the needle bar slider 23 reciprocates on it; the needle bar slider 23 drives the needle bar 24 to move up and down, and a suture needle 25 is installed at the bottom end of the needle bar 24, and the needle bar 24 is connected to the body bracket 5 through a linear bearing.

[0101] The thread take-up mechanism 1 includes a thread take-up rod 11, which is L-shaped and is installed on the flywheel crank 21. The long side of the thread take-up rod 11 is the thread take-up rod I 111, which extends outward and has a thread hole 12 at the end. The short side of the thread take-up rod 11 is the thread take-up rod II 112, and the end of the thread take-up rod II 112 is connected to the flywheel crank 21 through the thread take-up crank 13; a thread take-up rocker 14 is hinged at the bending part of the thread take-up rod 11.

[0102] The needle gripping mechanism 3 includes a needle gripping block 31, mounted at the bottom end of a presser foot rod 32. The suture needle 25 passes through this block, assisting in the reciprocating motion of the suture needle 25. A presser foot slider 33 is mounted on the presser foot rod, hinged to a hinged plate 34. This hinged plate 34 is hinged to a presser foot wrench 35 via a connecting rod Ⅰ 36. This hinged plate 34 is hinged to an eccentric shaft crank 38 via a connecting rod Ⅱ 37. The eccentric shaft crank 38 is connected to the connecting rod Ⅱ 37 via an eccentric shaft 39, mounted on one side of the flywheel crank. The presser foot wrench 35 is used to adjust the height of the presser foot of the needle gripping mechanism 3 to accommodate fabric thicknesses and sewing requirements. The eccentric shaft crank 38 rotates the eccentric shaft 39 through a rotary motion, pushing the presser foot slider 33 to complete the work.

[0103] The thread hooking mechanism 4 includes a disc cam 41 and a cylindrical cam 42 , and the disc cam 41 and the cylindrical cam 42 are combined to realize the combined motion of the reciprocating swing and linear motion of the hook needle 43 .

[0104] The disc cam 41 and cylindrical cam 42 are mounted on the main shaft 8. A gasket is placed between the cylindrical cam 42 and the disc cam 41 to reduce frictional wear on the cams. The main shaft 8 is driven by the motor 9. The disc cam 41 drives the push rod I 44 to drive the connecting rod 45, which causes the hook swing arm 46 to rotate. The hook swing arm 46 drives the hook shaft 47 to rotate. The hook 43 is mounted on the hook shaft 47 to realize the rotation of the hook 43. This is a derivative mechanism of the crank slider mechanism.

[0105] The cylindrical cam 42 drives the push rod II 48 to make the push rod II 48 perform linear reciprocating motion. The push rod support platform 49 is provided to make the linear reciprocating motion of the push rod II 48 more stable. The push rod II 48 is connected to the guide rail 410. The linear reciprocating motion of the push rod II 48 drives the linear motion of the guide rail 410. A pin is installed at the end of the guide rail 410, and the pin cooperates with the hook groove 411 of the hook 43, so that the linear reciprocating motion of the push rod II 48 drives the linear reciprocating motion of the hook 43.

[0106] The present invention can realize the bilateral stitching of carbon / carbon composite material preforms with a thickness of 50 mm or more, so that the stitched carbon / carbon composite material has a three-dimensional structure.

[0107] In response to the demand for a carbon fiber composite material preform with a hollow cone shape of 50 mm in thickness, 800 mm in height, and a maximum radius of 250 mm, this embodiment innovatively designs a long-arm thick material stitching device to achieve bilateral chain stitching of this special preform.

[0108] A design method for a long-arm thick material sewing device comprises the following steps:

[0109] S1. Determination of the piercing mechanism: The piercing mechanism adopts a crank slider mechanism to realize the reciprocating motion of the suture needle. Since the thickness of the carbon / carbon composite material to be sewn is 50mm and its outer structure is a circular curved surface, it is assumed that the thickness of the carbon / carbon composite material to be sewn is The distance from the needle hole of the suture needle 25 to the bottom surface of the carbon / carbon composite material is preferably 15 to 25 mm, considering the various positional relationships of the suture needle 25 when suturing the material, that is, when the suture needle 25 reaches the lowest end, in order to enable the hook 43 to hook the thread loop well,

[0110] The fixed distance from the needle hole of the suture needle 25 to the needle tip of the suture needle 25 is 9 mm, so the distance from the needle tip of the suture needle 25 to the bottom surface of the carbon / carbon composite material is taken as When the suture needle 25 rises to the highest point, in order to prevent the carbon / carbon composite material from rubbing against the suture needle 25 tip when moving, the distance between the suture needle 25 tip and the upper surface of the carbon / carbon composite material is is 10 mm, so the motion stroke of the suture needle 25 is finally determined. , then the flywheel crank The working length is 50mm, the eccentricity b=15.6mm, and the length of the slider connecting rod is taken =105mm.

[0111] Kinematic analysis of the suturing mechanism: The suturing of carbon / carbon composite materials by a three-dimensional suturing device requires the cooperation of multiple mechanisms. Therefore, it is necessary to conduct a kinematic analysis of each key mechanism to understand whether its movement rules can meet the requirements of the suturing work.

[0112] The displacement, velocity, and acceleration of the needle bar 24 are analyzed by the vector method, and the corresponding curves are drawn by SOLIDWORKS.

[0113] like Figure 9 The figure shows the kinematic model of the piercing mechanism. The rotation center of the flywheel crank 21 is the center o, the length of the flywheel crank 21 is the radius L1, the horizontal direction is the x-axis, the vertical direction is the y-axis, and a rectangular coordinate system is established. The eccentricity is known to be b, and the angle between the horizontal direction and the vertical axis of point A is , flywheel crank 21 rotation angle , angular velocity of flywheel crank 21 , establish the length of the slider connecting rod 22 , slider connecting rod 22 angle , angular velocity of slider connecting rod 22 and the displacement of the needle bar 24 ,speed and acceleration mathematical model.

[0114] S11. Displacement calculation:

[0115] According to the vector composition theorem, the equation can be listed:

[0116] (1)

[0117] Converted to plural form, we get:

[0118] (2)

[0119] in , i is an imaginary unit;

[0120] Expanding formula (2) and taking the real and imaginary parts respectively yields:

[0121] (3)

[0122] (4)

[0123] S12, speed calculation:

[0124] By taking the time derivative of equation (2), the complex form of the velocity vector equation of the needle rod 24 can be obtained as follows:

[0125] (5)

[0126] Where, , ;

[0127] Multiply both sides of formula (5) by , expand and take the real part, and we get:

[0128] (6)

[0129] Taking the imaginary part, we get:

[0130] (7);

[0131] S13, acceleration calculation:

[0132] By taking the time derivative of equation (5), the complex form of the velocity vector equation of the needle rod 24 can be obtained as follows:

[0133] (8)

[0134] In formula (8), is the acceleration of the flywheel crank 21, is the acceleration of the slider connecting rod 22;

[0135] Multiply both sides of formula (8) by , expand and take the real part, and we get:

[0136] (9)

[0137] In formula (9), is the acceleration at the needle rod;

[0138] Taking the imaginary part, we get:

[0139] (10);

[0140] S2. Determination of the needle holding mechanism:

[0141] The suture needle 25 is a slender rod with one end fixed and the other end hinged. According to Euler's formula, the instability condition for the suture needle 25 needle rod 24 to be stable is:

[0142] (11)

[0143] In formula (11), Working length of suture needle without clamping end, elastic modulus , section moment of inertia , length factor ;

[0144] The maximum resistance of a suture needle 25 when puncturing a 50mm thick cone-shaped carbon / carbon composite material is 59.62N, then in the state without the needle holding mechanism, the working safety factor of the suture needle 25 is:

[0145] (12)

[0146] The value of n in formula (12) is less than the stability safety factor ,

[0147] Therefore, it can be seen that the present invention needs to design the needle holding mechanism 3 to increase the working safety factor of the suture needle 25 to maintain the stable operation of the suture needle 25. The motion diagram of the needle holding mechanism 3 is as follows Figure 10 shown.

[0148] S3. Determination of the thread taking-up mechanism: The working characteristics of the thread taking-up mechanism 1 depend on the up and down movement of the thread taking-up rod 11 through the thread hole 12. When the suture needle 25 descends, the thread taking-up rod 11 of the thread taking-up mechanism 1 also needs to descend to supply thread to the suture needle 25; then when the hook 43 hooks the upper thread, the thread taking-up rod 11 needs to continue to move downward to supply thread for the formation of the thread loop; when the thread loop is formed and the suture needle 25 moves upward, the thread taking-up rod 11 needs to remove the upper thread from the hook 43 to tighten the stitches formed in the carbon / carbon composite material to form a firm stitch, and draw out the upper thread from the thread ball to prepare for the formation of the next stitch.

[0149] In order to coordinate the actions of the material-piercing mechanism 2 and the thread-hooking mechanism 4 , we need to plan the trajectory (trajectory line) of the thread-taking rod 11 of the thread-taking mechanism 1 passing through the thread hole 12 .

[0150] The trajectory line shown in the thread taking mechanism 1 is the displacement trajectory line of the thread hole 12 required for the designed suture work. However, since the analytical method and the graphical method are relatively complex, it is difficult to obtain the corresponding trajectory line. Therefore, the present invention adopts a method of combining the graphical method with SOLIDWORDS simulation to select the appropriate length of the thread taking rod Ⅰ111 and the angle between the thread taking rod Ⅰ111 and the thread taking rod Ⅱ112. Size. Figure 11 The parameters in the model are imported into SOLIDWORDS for modeling and different points on the thread take-up rod Ⅰ111 are selected for simulation. The trajectory lines formed by the motion trajectory of some points on the thread take-up rod Ⅰ111 are as follows: Figure 12 shown.

[0151] S4. Determination of the hooking mechanism:

[0152] The present invention adopts a combination of a double cam mechanism (ie, a cylindrical cam 42 and a geometrically closed groove disc cam 41 ) to achieve the combined reciprocating swing and linear motion of the hook needle 43 .

[0153] S41. Calculation of disc cam mechanism:

[0154] The movement diagram is as follows Figure 13 As shown, the push rod I 44 is 100 mm long, the connecting rod 45 is 298.99 mm long, and the hook swing rod 46 is 15 mm long.

[0155] In order to achieve that the hook 43 can better hook the suture and form a loop, the hook 43 swing angle is required to be ≥35°. The hook 43 rotation angle is set to 40°. The relationship between the hook 43 rotation angle and the contour line of the disc cam 41 is calculated by MATLAB software. The data of the push rod I 44, the connecting rod 45, and the hook swing rod 46 are input into MATLAB to calculate the contour line of the disc cam 41. Through the theoretical calculation of the contour line of the disc cam 41, the theoretical contour line of the disc cam and the actual contour line can be obtained as shown in the figure. Figure 14 and Figure 15 shown.

[0156] S42. Calculation of cylindrical cam mechanism:

[0157] Because the chain sewing method is adopted, it can be seen that the hook 43 first hooks the thread loop from one side of the suture needle 25, and then moves to the other side of the suture needle 25. As the suture needle 25 falls again, it falls between the bottom line and the hook 43, thereby completing the locking action.

[0158] The linear displacement a of the hook 43 is as follows: Figure 16In the figure, the z position is the position before the hook 43 moves, z' is the position after the hook 43 moves, s is the gap between the hook 43 and the suture needle 25, and s=0.5mm. Since the hook 43 is wedge-shaped, Figure 16 As shown in the figure, the thickness m of the crochet needle 43 is 1.5 mm, and the diameter d of the suture needle is 2 mm. Then the moving stroke a of the crochet needle 43 is:

[0159]

[0160] Based on the motion planning of the hook 43 movement law and the determined movement stroke of the hook 43, the above corresponding data are input into MATLAB, and the actual profile of the cylindrical cam 42 can be calculated as follows: Figure 17 shown.

[0161] S5. Determination of motor and reducer:

[0162] The present invention requires a motor 9 to drive, and the motor 9 drives the main shaft 8 for transmission. The main shaft drives the flywheel crank 21, the disc cam 41 and the cylindrical cam 42 to rotate. The motor 9 is an AC servo motor. When the piercing mechanism 2 sews carbon / carbon composite materials, its suture needle speed is 150-400r / min, then the transmission ratio is 15, and the needle speed is 200r / min.

[0163] The motor model is determined to be a 400W JMC servo motor with a rated torque of 1.27N∙m, a rated power of 400W, and a rated speed of 3000r / min. The reducer 10 is an NMRV 040 reducer with a reduction ratio of 15.

[0164] In addition, it also includes the determination of the overall shape of the machine and the shell of the hooking mechanism:

[0165] Due to the limited dimensions of the carbon / carbon composite material used for three-dimensional stitching, the space occupied by the thread hook mechanism 4 needs to be as small as possible. As the overall shape of the machine, which supports the operation of the entire device, is naturally more important. Conventional industrial sewing machines, which also function as double-sided stitching devices, typically have a relatively large outer shell for the rotary hook (or shuttle) at the bottom. Using a larger outer shell would make it difficult to achieve a sufficient area for double-sided stitching of the carbon / carbon composite material described in the present invention. Therefore, the present invention sets the overall machine shape to a C-shape. The bottom outer shell portion utilizes a hollow, non-regular hexahedron as the thread hook mechanism housing 7. This ensures that when the hook needle 43 passes through the stitching thread from one side, the angle change is supported by these intersecting structural components in three-dimensional space, thereby forming a reliable thread hook mechanism. To facilitate the disassembly and assembly of the bottom components, the cavity portion is decomposed into four structural components: a front cover 71, a hook upper cover 72, a cavity upper shell 73, and a cavity base shell 74.

[0166] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent.

Claims

1. A design method for a long-arm thick material sewing device, characterized by: It comprises a long-arm type thick material sewing device, which comprises a thread taking-up mechanism, a material pricking mechanism, a thread hooking mechanism and a needle holding mechanism, the material pricking mechanism comprises a flywheel crank, the flywheel crank is mounted on the main shaft, the flywheel crank is hinged to the slider connecting rod, the slider connecting rod is hinged to the needle bar slider, the needle bar slider drives the needle bar to move up and down, and a sewing needle is mounted on the bottom end of the needle bar; the thread taking-up mechanism comprises a thread taking-up rod, the thread taking-up rod is L-shaped, the thread taking-up rod is mounted on the flywheel crank, the long side of the thread taking-up rod is the thread taking-up rod I, the thread taking-up rod I extends outward and is provided with a The thread-passing hole is provided, and the short side of the thread-taking lever is the thread-taking lever II, and the end of the thread-taking lever II is connected to the flywheel crank through the thread-taking crank; the thread-taking lever is hinged with a thread-taking rocker at the bending part; the needle-holding mechanism includes a needle-holding block, which is installed at the bottom end of the presser foot rod, and the suture needle is arranged through the needle-holding block, and the presser foot rod is installed with a presser foot slider; the thread-hooking mechanism includes a disc cam and a cylindrical cam, and the disc cam and the cylindrical cam are both installed on the main shaft, and the disc cam drives the connecting rod to rotate the crochet swing arm by driving the push rod I, and the crochet swing arm drives the crochet shaft to rotate, and the crochet is installed on On the hook shaft; the cylindrical cam drives the push rod II, the push rod II is connected to the guide rail, and the guide rail drives the hook to realize linear reciprocating motion; the thread picking mechanism, the material piercing mechanism, the needle holding mechanism and the thread hooking mechanism are all installed on the body bracket, and the body bracket is installed with a flange interface, and the body bracket is connected and fixed to the industrial sewing machine through the flange interface; a thread hooking mechanism shell is provided at the bottom of the body bracket, and the cross-section of the thread hooking mechanism shell is a hollow hexagon, and the thread hooking mechanism shell includes a front cover, a hook upper cover, a cavity upper shell and a cavity base shell, and the cavity upper shell and the cavity base shell After buckling, the thread hooking mechanism cavity is fixed by a connecting piece, the front cover is fixed to the front end of the thread hooking mechanism cavity, and the hook upper cover is installed on the top of the cavity upper shell; the presser foot slider is hinged with a hinged plate, the hinged plate is hinged to the presser foot wrench through a connecting rod I, the hinged plate is hinged to the eccentric shaft crank through a connecting rod II, the eccentric shaft crank is connected to the connecting rod II through an eccentric shaft, and the eccentric shaft crank is installed on one side of the flywheel crank; a gasket is provided between the cylindrical cam and the disc cam; the main shaft is driven by a motor; a pin is installed at the end of the guide rail, and the pin cooperates with the hook groove of the hook; The design method of the long-arm thick material sewing device comprises the following steps: S1. Determination of the piercing mechanism: Set the thickness of the carbon / carbon composite material to be sutured to According to the distance from the suture needle hole to the bottom surface of the carbon / carbon composite material when the suture needle reaches the lowest end and the fixed distance from the suture needle hole to the suture needle tip, the distance from the suture needle tip to the bottom surface of the carbon / carbon composite material is taken as When the suture needle rises to the highest point, the distance between the suture needle tip and the upper surface of the carbon / carbon composite material is , and finally determine the motion stroke of the suture needle to be , and then determine the working length of the flywheel crank , eccentricity b and slider connecting rod length ; S2. Determination of the needle holding mechanism: The instability condition for the suture needle shaft to be stable is: (11) In formula (11), is the working length of the suture needle, is the elastic modulus, is the moment of inertia of the section, is the length factor; Calculate the maximum resistance of the suture needle to puncture the cone-shaped carbon / carbon composite material with different thicknesses , in the state without the needle holding mechanism, the working safety factor of the suture needle is: (12) In formula (12), The value of stability safety factor In contrast, the value of n is less than When suturing, it is necessary to design a needle holding mechanism to increase the working safety factor of the suture needle and to maintain the stable operation of the suture needle; S3. Determination of thread taking-up mechanism: Plan the trajectory of the thread hole on the thread take-up rod of the thread take-up mechanism: select the appropriate length of thread take-up rod I and the angle between thread take-up rod I and thread take-up rod II The size of , and different points on the thread take-up rod Ⅰ are selected for simulation to obtain the trajectory formed by the motion trajectory of some points on the thread take-up rod Ⅰ; S4. Determination of the hooking mechanism: S41. Calculation of disc cam mechanism: Set the length of push rod I, the length of connecting rod, the length of hook swing arm and the hook rotation angle, calculate the relationship between the hook rotation angle and the disc cam profile, and obtain the disc cam profile; S42. Calculation of cylindrical cam mechanism: During sewing, the hook moves horizontally. If the gap between the hook and the suture needle is s, the hook thickness is m, and the suture needle diameter is d, the moving stroke a of the hook is: The profile of the cylindrical cam is calculated based on the moving stroke a of the hook.

2. The design method of the long-arm thick material sewing device according to claim 1, characterized in that: In step S1, kinematic analysis calculation is performed on the determined piercing mechanism: With the rotation center of the flywheel crank as the center o, the length of the flywheel crank as the radius L1, the horizontal direction as the x-axis, and the vertical direction as the y-axis, a rectangular coordinate system is established. The eccentricity is known to be b, and the angle between the horizontal direction and the vertical axis of point A is , flywheel crank angle , flywheel crank angular velocity , slider connecting rod length , slider connecting rod angle , slider-connecting rod angular velocity , establish the displacement at the needle bar ,speed and acceleration The equation, S11. Displacement calculation: According to the vector composition theorem, the equation can be listed: （1） Converted to plural form, we get: （2） in , i is an imaginary unit; Expanding formula (2) and taking the real and imaginary parts respectively yields: （3） （4）； S12, speed calculation: Taking the time derivative of Equation (2) we can get the complex form of the velocity vector equation of the needle rod, which is: （5） Where, , ; Multiply both sides of formula (5) by , expand and take the real part, and we get: （6） Taking the imaginary part, we get: （7）； S13. Acceleration calculation: By taking the time derivative of Equation (5), we can obtain the complex form of the velocity vector equation of the needle rod, which is: （8） In formula (8), is the acceleration of the flywheel crank 21, is the acceleration of the slider connecting rod 22; Multiply both sides of formula (8) by , expand and take the real part, and we get: （9） In formula (9), is the acceleration at the needle rod; Taking the imaginary part, we get: （10）。

Images