Thread sewing machine with needle guide
By setting an independent needle-guiding mechanism for each threading needle, the problems of needle wobbling and deviation are solved, thereby improving the stability and reliability of the threading needle and ensuring the success rate of threading and the quality of binding.
Patent Information
- Application Number
- CN202522731135.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-11-06
- Estimated Expiration
- 2035-12-24
AI Technical Summary
Traditional thread-binding machines lack an independent needle-guiding mechanism, which causes the threading needle to easily shake or deviate during the threading process. Especially when binding small holes, the friction and resistance are high, which may cause the needle to bend or break, resulting in poor stability and reliability.
An independent needle-threading guide mechanism is set at each needle, including a needle-threading guide block and a guide post, to provide a stable intermediate support point. The guide block is supported by a spring to ensure the radial constraint of the needle on the inner wall of the guide hole, forming a double guide and support.
It improves the durability and stability of the threading needle, avoids bending or breaking, ensures accurate threading alignment, and increases the success rate of threading and binding efficiency.
Smart Images
Figure CN224940844U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of thread binding machine technology, and in particular to a thread binding machine with a needle guiding mechanism. Background Technology
[0002] A thread-binding machine is an office equipment that uses binding thread as the binding medium to bind paper documents such as financial vouchers and archives. A thread-binding machine typically includes a drilling device and a threading device. First, the drilling device drills holes in the binding material, and then the threading device passes the binding thread through the holes to facilitate subsequent knotting and binding. The threading device usually includes a threading drive mechanism, a threading slide, and a threading needle. The threading needle is fixed to the threading slide, and the threading drive mechanism drives the threading slide to rise and fall, causing the threading needle to lift the binding thread from below and pass it through the binding hole. However, only the lower end of the threading needle is fixed to the threading slide; its upper end is free, forming a cantilever structure. During threading, the threading needle may wobble and easily deviate from the binding hole. Traditional thread-binding machines lack a dedicated needle-guiding mechanism for the threading needles. Instead, they rely solely on needle holes in the binding platform that holds the bound materials, guiding the needles through these holes. Because the binding platform is a thin plate structure, the thread holes are short, limiting their guiding effect on the needles and failing to provide resistance to lateral forces. This results in a cantilever beam structure during the needle's movement, leading to excessive freedom and poor stability. Furthermore, when the binding hole is small, the binding thread protruding from the needle rubs against the bound materials, generating significant resistance. This can cause the needles to bend or even break, further compromising reliability and stability. Therefore, improvements are necessary. Utility Model Content
[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a thread-binding machine with a needle-guiding mechanism. The independent needle-guiding mechanism enhances the guiding effect and radial support of the thread-binding needle, avoids bending or even breaking of the thread-binding needle, and improves reliability and stability.
[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a thread-binding machine with a needle-guiding mechanism, comprising a binding platform, a drilling device, and a threading device. The drilling device is located above the binding platform, and the threading device is located below the binding platform. The threading device is provided with a threading slide that is slidably mounted below the binding platform. At least one threading needle is fixedly mounted on the threading slide. At least one needle-guiding mechanism is provided below the binding platform. The needle-guiding mechanism includes a needle-guiding block and two needle-guiding posts. The two needle-guiding posts are vertically mounted on the left and right sides of the threading needle, respectively. The left and right sides of the needle-guiding block are fixedly or slidably mounted on the two needle-guiding posts, respectively. The needle-guiding block is located between the binding platform and the threading slide. A needle-guiding hole is opened in the middle of the needle-guiding block corresponding to the position of the threading needle, and a needle-guiding hole is opened in the binding platform corresponding to the position of the needle-guiding hole, passing through the binding platform. In the initial state, the upper end of the threading needle passes through the needle-guiding hole and is inserted into the needle-guiding hole.
[0005] In a further technical solution, the needle-threading guide mechanism is also provided with two springs. The two springs are respectively sleeved on the two needle-threading guide posts. The left and right sides of the needle-threading guide block are slidably installed on the two needle-threading guide posts. The upper ends of the two springs abut against the needle-threading guide block, and the lower ends of the two springs abut against the thread-threading slide block.
[0006] In a further technical solution, a guide gap is provided between the needle-threading guide block and the binding platform.
[0007] In a further technical solution, the diameter of the needle guide hole is equal to or greater than the diameter of the needle.
[0008] In a further technical solution, the diameter of the needle guide hole is larger than the diameter of the needle, and the gap between the inner wall of the needle guide hole and the outer wall of the needle is 0.01~10mm.
[0009] In a further technical solution, a needle fixing hole is provided on the threading slide corresponding to the position of the threading needle. The lower part of the threading needle is inserted into the needle fixing hole. Guide post through holes are provided on the left and right sides of the needle fixing hole, and the two needle guide posts of the needle guiding mechanism pass through the two guide post through holes respectively.
[0010] In a further technical solution, a lower box is fixedly installed on the lower part of the binding platform, and a threading device is set in the lower box. Two sliding guide posts are set in the lower box. The threading slide is slidably installed on the two sliding guide posts through a linear bearing. The diameter of the through hole of the guide post is larger than the diameter of the needle guide post. The upper end of the needle guide post is fixedly installed on the lower part of the binding platform, and the lower end of the needle guide post is fixedly installed on the bottom wall of the lower box.
[0011] In a further technical solution, the upper end of the threading needle is provided with an upward-facing top thread groove, and the left and right sides of the threading needle are respectively provided with thread receiving grooves. Both thread receiving grooves pass through the threading needle along the length direction of the threading needle, and the cross-sectional shape of the thread receiving grooves is arc-shaped. The lower part of the threading needle is provided with a fixed plane, and one side of the threading slide is provided with a fixed threaded hole. The fixed threaded hole is connected to the needle fixing hole, and a fastening screw is connected to the threaded hole. The fastening screw extends into the needle fixing hole and abuts against the fixed plane.
[0012] In a further technical solution, an avoidance notch is provided at the rear of the needle-threading guide block.
[0013] In a further technical solution, three threading needles are spaced apart along the horizontal direction on the threading slide, and three threading guide mechanisms are provided below the corresponding binding platform. Two threading guide posts of each threading guide mechanism are respectively set on the left and right sides of each threading needle, and each threading needle passes through the threading guide hole of each threading guide mechanism. The threading device is also equipped with a threading drive mechanism, which includes a threading drive motor, a threading drive gear, and a threading drive rack. The threading drive motor is fixedly installed below the binding platform, the threading drive gear is fixedly installed on the output shaft of the threading drive motor, and the threading drive rack is fixedly installed on the threading slide. The threading drive gear meshes with the threading drive rack.
[0014] The advantages of this invention compared to the prior art are as follows: by setting an independent needle-guiding mechanism for each threading needle, the needle-guiding hole of the needle-guiding block forms a stable intermediate support point for the upper part of the threading needle. During the rising process of the threading needle, the upper part of the threading needle can always be radially constrained by the inner wall of the needle-guiding hole. When the threading encounters resistance, it can effectively resist lateral force and prevent the threading needle from breaking due to lateral bending stress concentration, thereby improving the durability and reliability of the entire threading device.
[0015] The thickness of the needle guide block is selected according to the thickness of the threading needle to accommodate threading needles of different thicknesses. It provides a longer guiding contact surface for the threading needle, corrects the perpendicularity of the threading needle, and ensures that the threading needle is accurately aligned with the needle hole on the binding platform and the binding hole on the bound material. This avoids friction, needle jamming, or threading failure caused by misalignment, and improves the threading success rate. Furthermore, the needle guide hole and the needle hole form a double guide and support, which can further enhance the guiding and supporting effect on the threading needle. Attached Figure Description
[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0017] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is the utility model Figure 1 Enlarged view of part A; Figure 3 This is a cross-sectional view of the present invention; Figure 4 This is an exploded view of the threading device and needle guiding mechanism of this utility model.
[0018] In the picture: 1. Binding platform; 11. Needle hole; 12. Lower box body; 13. Slide guide post; 2. Drilling equipment; 3. Threading device, 31. Threading slide, 311. Needle fixing hole, 312. Guide post through hole, 313. Linear bearing, 314. Fixing threaded hole, 315. Fastening screw, 32. Threading needle, 321. Top Thread groove, 322. Thread receiving groove, 323. Fixing plane, 331. Threading drive motor, 332. Threading drive gear, 333. Threading drive rack; 4. Needle-threading guide mechanism, 41. Needle-threading guide block, 411. Needle-threading guide hole, 412. Avoidance notch, 42. Needle-threading guide post, 43. Spring, 44. Guide gap. Detailed Implementation
[0019] The following are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention.
[0020] A thread-binding machine with a needle-guiding mechanism, such as Figures 1 to 4As shown, the binding platform includes a binding platform 1, a drilling device 2, and a threading device 3. The drilling device 2 is located above the binding platform 1, and the threading device 3 is located below the binding platform 1. The threading device 3 has a threading slide 31 that slides vertically below the binding platform 1. At least one threading needle 32 is fixedly mounted on the threading slide 31. At least one needle guiding mechanism 4 is located below the binding platform 1. The needle guiding mechanism 4 includes a needle guiding block 41 and two needle guiding posts 42. The two needle guiding posts 42 are vertically arranged on the threading platform 1. The needle 32 is fixed or slidably mounted on the left and right sides of the needle guide block 41, respectively. The needle guide block 41 is located between the binding platform 1 and the threading slide 31. The middle part of the needle guide block 41 is provided with a needle guide hole 411 that passes through the needle guide block 41, corresponding to the position of the threading needle 32. The binding platform 1 is provided with a needle hole 11 that passes through the binding platform 1, corresponding to the position of the needle guide hole 411. In the initial state, the upper end of the threading needle 32 passes through the needle guide hole 411 and is inserted into the needle hole 11. Traditional thread-binding machines lack independent needle-guiding mechanisms, relying solely on the needle-hole 11 of the binding platform 1 to guide and support the threading needle 32. This results in weak radial constraint on the threading needle 32, making it prone to bending or even breakage. In contrast, this invention provides an independent needle-guiding mechanism for each threading needle 32. The needle-guiding hole 411 of the needle-guiding block 41 forms a stable intermediate support point for the upper part of the threading needle 32. During the upward movement of the threading needle 32, its upper part is always radially constrained by the inner wall of the needle-guiding hole 411. When encountering resistance during threading, it effectively resists lateral forces, preventing the threading needle 32 from breaking due to stress concentration caused by lateral bending. This improves the durability and reliability of the entire threading device 3. The thickness of the needle guide block 41 is selected according to the thickness of the threading needle to accommodate threading needles 32 of different thicknesses. It provides a longer guiding contact surface for the threading needle 32, which can correct the perpendicularity of the threading needle 32 and ensure that the threading needle 32 is accurately aligned with the needle hole 11 on the binding platform 1 and the binding hole on the bound object. This avoids friction, needle jamming or threading failure caused by misalignment, and improves the threading success rate. Furthermore, the needle guide hole 411 and the needle hole 11 form a double guide and support, which can further improve the guiding and supporting effect on the threading needle.
[0021] Specifically, the needle-threading guide mechanism 4 is further provided with two springs 43, which are respectively sleeved on the two needle-threading guide posts 42. The left and right sides of the needle-threading guide block 41 are slidably mounted on the two needle-threading guide posts 42. The upper ends of the two springs 43 abut against the needle-threading guide block 41, and the lower ends of the two springs 43 abut against the thread-threading slide block 31. The needle-threading guide block 41 is slidably mounted on the needle-threading guide post 42 and supported by the springs 43, forming a floating needle-threading guide block 41. When threading, the thread-threading slide block 31 moves upward, causing the springs 43 to move upward synchronously. The springs 43 then push the needle-threading guide block 41 upward together until the needle-threading guide block 41 abuts against the lower part of the binding platform 1. Thus, in the initial stage of the upward movement of the thread-threading needle 32, the needle-threading guide block 41 moves upward with the thread-threading needle 32, thereby achieving follow-up support. The spring 43 provides support, reducing friction between the threading needle 32 and the threading guide block 41. After the threading guide block 41 abuts against the binding platform 1, the threading slide 31 continues to move upward, compressing the spring 43 and pressing the threading guide block 41 tightly against the lower part of the binding platform 1. This connects the threading guide hole 411 and the threading hole 11, forming a longer guide hole and preventing gaps between the threading guide hole 411 and the threading hole 11, which could cause the threading needle 32 to bend between them. When the threading slide 31 is manually driven to rise or fall, the spring 43 also functions to reset the threading slide 31. The floating threading guide block 41 does not occupy vertical space and does not increase the overall size of the machine.
[0022] Specifically, a guide gap 44, ranging from 3 to 50 mm, is provided between the needle guide block 41 and the binding platform 1. This guide gap 44 ensures that the needle guide block 41 is initially positioned relatively close to the center of the threading needle 32, preventing the needle 32 from bending during handling or drops. During threading, the needle guide block 41 moves upward under the push of the spring 43, gradually reducing the guide gap 44. When the needle guide block 41 is fixed to the needle guide post 42, the guide gap 44 would occupy vertical space, increasing the overall size of the machine. Therefore, setting the guide gap 44 to 3-50 mm ensures effective guidance and support for the center of the threading needle 32 while minimizing vertical space occupation.
[0023] Specifically, when the diameter of the needle guide hole 411 is equal to the diameter of the threading needle 32, the needle guide hole 411 can provide maximum radial constraint and support for the threading needle 32, but it will cause friction between the threading needle 32 and the needle guide block 41, increasing the moving resistance of the threading needle 32. When the diameter of the needle guide hole 411 is larger than the diameter of the threading needle 32, the gap between the inner wall of the needle guide hole 411 and the outer wall of the threading needle 32 is 0.01~10mm. By reducing the gap between the inner wall of the needle guide hole 411 and the outer wall of the threading needle 32, greater radial constraint and support force can be provided while avoiding friction. Preferably, the gap between the inner wall of the needle guide hole 411 and the outer wall of the threading needle 32 is 0.1~3mm.
[0024] Specifically, the threading slide 31 has a needle fixing hole 311 corresponding to the position of the threading needle 32. The lower part of the threading needle 32 is inserted into the needle fixing hole 311. Guide post through holes 312 are respectively opened on the left and right sides of the needle fixing hole 311, which penetrate the threading slide 31. The two needle guide posts 42 of the needle guiding mechanism 4 pass through the two guide post through holes 312 respectively. The needle guide posts 42 pass through the threading slide 31 through the guide post through holes 312. The needle guide posts 42 do not need to be bent to avoid the threading slide 31. It also allows the needle guide holes 411 to be positioned in the middle of the needle guide block 41, avoiding uneven force on the needle guide block 41 caused by offset installation, so that the needle guide holes 411 will be skewed and interfere with the threading needle 32, thus improving reliability and stability. In addition, the guide post through holes 312 can also limit the movement of the threading slide 31, further improving the movement stability of the threading slide 31.
[0025] Specifically, a lower box 12 is fixedly installed at the lower part of the binding platform 1. A threading device 3 is disposed within the lower box 12. Two sliding guide posts 13 are provided within the lower box 12. A threading slide 31 is slidably mounted on the two sliding guide posts 13 via a linear bearing 313. The diameter of the through hole 312 in the guide post is larger than the diameter of the needle guide post 42. The upper end of the needle guide post 42 is fixedly installed at the lower part of the binding platform 1, and the lower end of the needle guide post 42 is fixedly installed on the bottom wall inside the lower box 12. The lower box 12 serves to support the binding platform 1, acting not only as an outer shell but also as a support structure. Furthermore, the use of the sliding guide posts 13 and the needle guide post 42 as internal supports improves structural strength, simplifies the structure, and reduces costs. The linear bearing 313 reduces the friction between the slide guide post 13 and the threading slide 31. At the same time, the diameter of the guide post through hole 312 is larger than the diameter of the needle threading guide post 42 so that the threading slide 31 does not come into contact with the needle threading guide post 42, thus avoiding friction and improving the lifting stability and smoothness of the threading slide 31.
[0026] Specifically, the upper end of the threading needle 32 is provided with an upward-facing top thread groove 321, and the left and right sides of the threading needle 32 are respectively provided with thread receiving grooves 322. Both thread receiving grooves 322 penetrate the threading needle 32 along the length direction of the threading needle 32, and the cross-sectional shape of the thread receiving grooves 322 is arc-shaped. The lower part of the threading needle 32 is provided with a fixing plane 323, and one side of the threading slide 31 is provided with a fixing threaded hole 314. The fixing threaded hole 314 is connected to the needle fixing hole 311, and a fastening screw 315 is threaded into the fixing hole 314. The fastening screw 315 extends into the needle fixing hole 311 and abuts against the fixing plane 323. The arc-shaped thread groove 322 can fit the binding thread with a circular cross-section, thereby reducing the amount of binding thread exposed to the threading needle 32 and reducing threading resistance. When threading, the binding platform 1 has a transverse groove for placing the binding thread in the transverse direction. The needle hole 11 is located on the transverse groove. The binding thread is placed in the transverse groove. As the threading needle 32 gradually moves upward, it extends into the transverse groove and causes the binding thread to fall into the top thread groove 322. The threading needle 32 continues to move upward. When passing through the binding hole, the binding thread is accommodated in the thread groove 322 until the threading needle 32 extends out of the binding and passes the binding thread through the binding hole.
[0027] Specifically, a clearance notch 412 is provided at the rear of the needle guide block 41. When drilling, the thread-binding machine often needs to slide and install a conductive rubber pad on the binding platform 1 to avoid interference between the drill bit of the drilling device 2 and the binding platform 1, which would cause the drill bit to collide. During drilling, the conductive rubber pad will move directly below the drill bit. When the drilling is completed and the thread is being threaded, the conductive rubber pad will move backward to avoid the needle hole 11, so as to avoid interference with the threading needle 32. The clearance notch 412 avoids the conductive rubber pad, preventing interference between the needle guide block 41 and the conductive rubber pad.
[0028] Specifically, three threading needles 32 are spaced apart along the horizontal direction on the threading slide 31. Correspondingly, three needle guiding mechanisms 4 are provided below the binding platform 1. Two needle guide posts 42 of each needle guiding mechanism 4 are respectively positioned on the left and right sides of each threading needle 32. Each threading needle 32 passes through the needle guide hole 411 of its respective needle guiding mechanism 4. The threading device 3 also includes a threading drive mechanism, comprising a threading drive motor 331, a threading drive gear 332, and a threading drive rack 333. The threading drive motor 331 is fixedly installed below the binding platform 1, the threading drive gear 332 is fixedly installed on the output shaft of the threading drive motor 331, and the threading drive rack 333 is fixedly installed on the threading slide 31. The threading drive gear 332 meshes with the threading drive rack 333. By setting multiple threading needles 32 and corresponding independent guiding mechanisms, threading operations for multiple binding holes can be completed at once, improving binding efficiency, and is particularly suitable for binding financial documents and archives. Each threading needle 32 is equipped with an independent guiding mechanism, ensuring that each threading needle 32 maintains the same stability and centering accuracy when multiple needles are working simultaneously. This avoids mutual interference or individual needle bending caused by uneven force on each threading needle 32, thus guaranteeing the overall binding quality. The threading drive mechanism uses a threading drive motor 331 to drive the threading drive gear 332 to rotate, which in turn drives the threading slide 31 to automatically rise and fall via the threading drive rack 333, making it more convenient to use.
Claims
1. A thread-binding machine with a needle-guiding mechanism, comprising a binding platform (1), a drilling device (2), and a threading device (3), wherein the drilling device (2) is disposed above the binding platform (1), the threading device (3) is disposed below the binding platform (1), and the threading device (3) is provided with a threading slide (31) which is slidably mounted below the binding platform (1), and at least one threading needle (32) is fixedly mounted on the threading slide (31), characterized in that: At least one needle-threading guide mechanism (4) is provided below the binding platform (1). The needle-threading guide mechanism (4) includes a needle-threading guide block (41) and two needle-threading guide posts (42). The two needle-threading guide posts (42) are respectively vertically arranged on the left and right sides of the threading needle (32). The left and right sides of the needle-threading guide block (41) are respectively fixed or slidably installed on the two needle-threading guide posts (42). The needle-threading guide block (41) is located between the binding platform (1) and the threading slide (31). The middle part of the needle-threading guide block (41) is provided with a needle-threading guide hole (411) that passes through the needle-threading guide block (411) corresponding to the position of the threading needle (32). The binding platform (1) is provided with a needle-threading hole (11) that passes through the binding platform (1) corresponding to the position of the needle-threading guide hole (411). In the initial state, the upper end of the threading needle (32) passes through the needle-threading guide hole (411) and is inserted into the needle-threading hole (11).
2. The thread-binding machine with a needle-guiding mechanism according to claim 1, characterized in that: The needle-threading guide mechanism (4) is also provided with two springs (43), which are respectively sleeved on the two needle-threading guide posts (42). The left and right sides of the needle-threading guide block (41) are respectively slidably installed on the two needle-threading guide posts (42). The upper ends of the two springs (43) abut against the needle-threading guide block (41), and the lower ends of the two springs (43) abut against the threading slide (31).
3. A thread-binding machine with a needle-guiding mechanism according to claim 1, characterized in that: A guide gap (44) is provided between the needle guide block (41) and the binding platform (1).
4. A thread-binding machine with a needle-guiding mechanism according to claim 1, characterized in that: The diameter of the needle guide hole (411) is equal to or greater than the diameter of the needle (32).
5. A thread-binding machine with a needle-guiding mechanism according to claim 4, characterized in that: The diameter of the needle guide hole (411) is larger than the diameter of the threading needle (32), and the gap between the inner wall of the needle guide hole (411) and the outer wall of the threading needle (32) is 0.01~10mm.
6. A thread-binding machine with a needle-guiding mechanism according to claim 1, characterized in that: The threading slide (31) has a needle fixing hole (311) corresponding to the position of the threading needle (32). The lower part of the threading needle (32) is inserted into the needle fixing hole (311). The left and right sides of the needle fixing hole (311) are respectively provided with guide post through holes (312) that pass through the threading slide (31). The two needle guide posts (42) of the needle guiding mechanism (4) pass through the two guide post through holes (312) respectively.
7. A thread-binding machine with a needle-guiding mechanism according to claim 6, characterized in that: The lower part of the binding platform (1) is fixedly installed with a lower box body (12). The threading device (3) is set inside the lower box body (12). Two sliding guide posts (13) are set inside the lower box body (12). The threading slide (31) is slidably installed on the two sliding guide posts (13) through a linear bearing (313). The diameter of the guide post through hole (312) is larger than the diameter of the needle guide post (42). The upper end of the needle guide post (42) is fixedly installed on the lower part of the binding platform (1), and the lower end of the needle guide post (42) is fixedly installed on the bottom wall inside the lower box body (12).
8. A thread-binding machine with a needle-guiding mechanism according to claim 6, characterized in that: The upper end of the threading needle (32) is provided with an upward-facing top thread groove (321), and the left and right sides of the threading needle (32) are respectively provided with thread receiving grooves (322). Both thread receiving grooves (322) penetrate the threading needle (32) along the length direction of the threading needle (32), and the cross-sectional shape of the thread receiving grooves (322) is arc-shaped. The lower part of the threading needle (32) is provided with a fixed plane (323), and the threading slide (31) is provided with a fixed threaded hole (314) on one side. The fixed threaded hole (314) is connected to the threading needle fixing hole (311). A fastening screw (315) is threaded into the fixed threaded hole (314). The fastening screw (315) extends into the threading needle fixing hole (311) and abuts against the fixed plane (323).
9. A thread-binding machine with a needle-guiding mechanism according to claim 1, characterized in that: The rear of the needle guide block (41) is provided with an avoidance notch (412).
10. A thread-binding machine with a needle-guiding mechanism according to any one of claims 1 to 9, characterized in that: The threading slide (31) is provided with three threading needles (32) spaced apart in the horizontal direction. Correspondingly, the binding platform (1) is provided with three threading guide mechanisms (4). The two threading guide posts (42) of each threading guide mechanism (4) are respectively located on the left and right sides of each threading needle (32). Each threading needle (32) passes through the threading guide hole (411) of each threading guide mechanism (4). The threading device (3) is also provided with a threading drive mechanism, which includes a threading drive motor (331), a threading drive gear (332), and a threading drive rack (333). The threading drive motor (331) is fixedly installed below the binding platform (1), the threading drive gear (332) is fixedly installed on the output shaft of the threading drive motor (331), and the threading drive rack (333) is fixedly installed on the threading slide (31). The threading drive gear (332) meshes with the threading drive rack (333).