Energy-saving motor rotating shaft convenient to assemble and preparation process thereof

Abstract

The application discloses an energy-saving motor rotating shaft convenient to assemble and a preparation process, which comprises a rotating shaft body, a connecting structure and an external shaft, the rotating shaft body is connected with the external shaft through the connecting structure; the connecting structure comprises a main connecting assembly installed at the end of the rotating shaft body and a secondary connecting assembly installed at the end of the external shaft, and the main connecting assembly is connected with the secondary connecting assembly in a matched mode; the connecting structure is arranged, the rotating shaft body and the external shaft can be quickly and conveniently assembled through the connecting structure, the problems of the traditional connecting mode being complicated and unstable are solved, and the preparation process of the motor rotating shaft adopts a tapping device to perform tapping, so that the threads of the connecting structure are more quickly and efficiently formed, the main connecting assembly and the secondary connecting assembly are more tightly connected in a threaded mode, and the stability of the motor rotating shaft connection is improved.

Description

Technical Field

[0001] This invention relates to the field of motor shaft technology, specifically to an energy-saving motor shaft that is easy to assemble and its manufacturing process. Background Technology

[0002] An electric motor is an electromagnetic device that converts or transmits electrical energy based on the law of electromagnetic induction. The motor shaft is an important component, and its performance directly affects the performance of the entire motor. It is a major driving component in modern industrial systems.

[0003] The existing patent publication number is CN212183294U. An easy-to-assemble motor shaft includes a motor body. A fixed shaft is installed inside the motor body. A first slider is fixedly connected to the surface of the fixed shaft away from the motor body. The surface of the first slider abuts against the inner wall of the driven shaft. A first fixing frame is fixedly connected to the surface of the driven shaft.

[0004] The existing patents and traditional motor shafts mentioned above have the following problems: when the rod needs to be extended to connect with external equipment, the connection method is cumbersome and the connection is unstable, which affects the transmission efficiency of the motor shaft. Therefore, an energy-saving motor shaft that is easy to assemble and a manufacturing process are designed. Summary of the Invention

[0005] The purpose of this invention is to provide an energy-saving motor shaft that is easy to assemble and its manufacturing process, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an energy-saving motor shaft that is easy to assemble, comprising a shaft body, a connecting structure and an external shaft, wherein the shaft body is connected to the external shaft through the connecting structure;

[0007] The connection structure includes a main connection component installed at the end of the rotating shaft body and a secondary connection component installed at the end of the external shaft, wherein the main connection component and the secondary connection component are connected in cooperation.

[0008] Preferably, the main connecting assembly includes a connector, a main locking hole, a main inner groove, a first internal thread, a protrusion, and a first external thread. The connector is integrally connected to the end of the rotating shaft body. The connector has a main inner groove in the middle and at least two sets of main locking holes on the edge. The inner wall of the main inner groove has a first internal thread, and a protrusion in the middle. The protrusion has a first external thread on its outside.

[0009] Preferably, the outer edge of the protrusion is flush with the outer edge of the connector.

[0010] Preferably, the secondary connecting assembly includes a connecting plate, a secondary locking hole, a sleeve, a second external thread, a secondary inner groove, and a second internal thread. One side of the connecting plate is integrally connected to the end of the external shaft. The connecting plate has a secondary locking hole corresponding to the main locking hole. The other side of the connecting plate has a sleeve. The sleeve has a second external thread on its exterior and a secondary inner groove on its interior. The inner wall of the secondary inner groove has a second internal thread. The sleeve and the main inner groove of the connecting head are embedded in each other, and the second external thread is threaded with the first internal thread. The protrusion and the secondary inner groove are embedded in each other, and the first external thread is threaded with the second internal thread.

[0011] This invention provides a manufacturing process for an energy-saving motor shaft that is easy to assemble, comprising the following steps:

[0012] S1. Material Selection: High-strength alloy steel is selected;

[0013] S2. Blank forming: The shaft blank is prepared by forging or precision casting.

[0014] S3. Machining: The outer shape is machined by turning on a lathe, the shoulder is pre-machined, and then the thread is machined by tapping.

[0015] S4. Heat treatment: Quenching and tempering, carburizing and quenching or induction hardening are adopted.

[0016] S5. Coating treatment: Apply a low-friction nano-coating to the surface of the rotating shaft;

[0017] S7. Assembly: Connect the main body of the rotating shaft and the external shaft through the connecting structure to complete the assembly.

[0018] Preferably, the tapping device includes a linkage mechanism, which is mounted on a locking seat and connected on the other side to a set of chuck feet. A tapping head is mounted on the linkage mechanism.

[0019] Preferably, the linkage mechanism includes a fixed base, a first bevel gear, a linkage rod, a first adjustment component, a second bevel gear, a second adjustment component, a swing rod, a first push rod, and a second push rod. The front side of the fixed base is mounted on a locking base. The first bevel gear is rotatably connected to one side of the fixed base. The linkage rod is rotatably connected to one side of the first bevel gear extending downward from the plate. The other end of the linkage rod is mounted on a set of chuck feet via the first adjustment component. The upper part of the fixed base is provided with a second bevel gear and is rotatably connected via a shaft. The second bevel gear meshes with the first bevel gear. The upper side of the second bevel gear is provided with a second adjustment component, and a swing rod is rotatably connected to the second adjustment component. The lower part of the other end of the swing rod is rotatably connected to a first push rod. The bottom of the first push rod is fixedly sleeved on one end of the second push rod. The other end of the second push rod, which passes through the fixed base and the first bevel gear, is connected to a tapping head.

[0020] Preferably, the first adjustment component includes a base plate, a guide post, a guide sleeve, and a locking bolt. The base plate is installed on the side of the clamping foot, and the base plate is provided with a guide post. The end of the linkage rod is provided with a through hole and a guide sleeve. The guide post slides through the through hole and the guide sleeve of the linkage rod. One side of the guide sleeve is provided with an opening, and a locking bolt for locking the guide post is provided in the opening.

[0021] Preferably, the second adjustment component includes a slider, a side fixing plate, and a threaded rod. The slider is slidably disposed in a slide rail opened on one side of the upper part of the second bevel gear, and a side fixing plate is installed on the outer side of the slide rail. A threaded rod is provided through the side fixing plate, and the threaded rod is threadedly connected to a threaded hole provided in the middle of the slider. The upper end of the slider is rotatably connected to one end of the swing rod.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention features a connection structure that allows for quick and easy assembly of the main shaft and the external shaft, solving the problems of cumbersome and unstable connections associated with traditional methods.

[0024] Furthermore, the connection structure includes a main connection assembly and a secondary connection assembly. The connector is aligned with the locking hole of the connecting plate and then fixed with bolts. At the same time, the sleeve is embedded in the main inner groove, so that the second external thread and the first internal thread are threaded together. Meanwhile, the protrusion extends into the secondary inner groove, so that the first external thread and the second internal thread are threaded together. Thus, the main shaft body and the external shaft are connected more tightly and stably through the main connection assembly and the secondary connection assembly, which is convenient to assemble.

[0025] The manufacturing process of the motor shaft of this invention uses a tapping device to tap the threads, which can make the threading of the connection structure faster and more efficient, making the threaded connection between the main connection component and the auxiliary connection component tighter, and improving the stability of the motor shaft connection.

[0026] Furthermore, the thread tapping device employs a linkage mechanism that connects the tapping head with the chuck's jaws, eliminating the need for an additional motor to drive the tapping head. This enables fast and efficient thread tapping, improving overall work efficiency. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] Figure 2 This is a schematic diagram of the main connection component of the present invention.

[0029] Figure 3 This is a schematic diagram of the structure of the secondary connection component of the present invention.

[0030] Figure 4 This is a rear view structural diagram of the secondary connection component of the present invention.

[0031] Figure 5 This is a schematic diagram of the tapping device of the present invention.

[0032] Figure 6 This is a side view of the tapping device of the present invention.

[0033] Figure 7 For the present invention Figure 6 A magnified structural diagram at point B in the middle.

[0034] Figure 8 This is a side view of an adjustment component of the present invention.

[0035] Figure 9 For the present invention Figure 5 A schematic diagram of the structure at point A in the middle.

[0036] In the diagram: Shaft body-1, Connecting structure-2, External shaft-3, Main connecting assembly-21, Secondary connecting assembly-22, Connector-211, Main locking hole-212, Main inner groove-213, First internal thread-214, Protrusion-215, First external thread-216, Connecting plate-221, Secondary locking hole-222, Sleeve-223, Secondary external thread-224, Secondary inner groove-225, Secondary internal thread-226, Linkage mechanism-4, Locking seat-5, Snap-fit 6. Disc - 7. Clamping foot - 8. Tapping head - 9. Fixed seat - 41. First bevel gear - 42. Connecting rod - 43. First adjusting component - 44. Second bevel gear - 45. Second adjusting component - 46. Swing rod - 47. First push rod - 48. Second push rod - 49. Base plate - 441. Guide column - 442. Guide sleeve - 443. Locking bolt - 444. Slider - 461. Side fixing plate - 462. Threaded rod - 463. Rotary shaft workpiece to be processed - a. Detailed Implementation

[0037] To further explain the technical solution of the present invention, a detailed description is provided below through specific embodiments.

[0038] Please see Figure 1 The present invention provides an energy-saving motor shaft that is easy to assemble, comprising a shaft body 1, a connecting structure 2 and an external shaft 3, wherein the shaft body 1 is connected to the external shaft 3 through the connecting structure 2;

[0039] The connection structure 2 includes a main connection component 21 installed at the end of the shaft body 1 and a secondary connection component 22 installed at the end of the external shaft 3. The main connection component 21 and the secondary connection component 22 are connected in cooperation, and the shaft body 1 and the external shaft 3 can be quickly and conveniently assembled through the connection structure 2.

[0040] Please see Figure 2 The main connecting component 21 of the present invention includes a connector 211, a main locking hole 212, a main inner groove 213, a first internal thread 214, a protrusion 215, and a first external thread 216. The connector 211 is integrally connected to the end of the rotating shaft body 1. The connector 211 has a main inner groove 213 in the middle and at least two sets of main locking holes 212 on the edge. In this embodiment, three sets of main locking holes 212 are provided, which can be locked with bolts for fixation, thereby improving the connection stability of the connecting structure 2. The inner wall of the main inner groove 213 is provided with a first internal thread 214, and a protrusion 215 is provided in the middle. The protrusion 215 is provided with a first external thread 216 on the outside.

[0041] The outer edge of the protrusion 215 is flush with the outer edge of the connector 211, which makes it easier for the sleeve 223 and the protrusion 215 to be connected more tightly, and improves the stability of the rotating shaft body 1 and the external shaft 3.

[0042] Please see Figures 3-4 The secondary connecting component 22 of the present invention includes a connecting plate 221, a secondary locking hole 222, a sleeve 223, a second external thread 224, a secondary inner groove 225, and a second internal thread 226. One side of the connecting plate 221 is integrally connected to the end of the external shaft 3. The connecting plate 221 is provided with a secondary locking hole 222 corresponding to the main locking hole 212. The sleeve 223 is provided on the other side of the connecting plate 221. The sleeve 223 is provided with a second external thread 224 on the outside and a secondary inner groove 225 on the inside. The inner wall of the secondary inner groove 225 is provided with a second internal thread 226. The sleeve 223 and the main inner groove 213 of the connecting head 211 are embedded in each other, and the second external thread 224 is threaded in with the first internal thread 214. The protrusion 215 and the secondary inner groove 225 are embedded in each other, and the first external thread 216 is threaded in with the second internal thread 226.

[0043] Specifically, the end face of the connector 211 of the main connecting component 21 is in contact with the end face of the connecting plate 221 of the secondary connecting component 22. At the same time, the sleeve 223 is embedded in the main inner groove 213, so that the second external thread 224 and the first internal thread 214 are threadedly engaged. Meanwhile, the protrusion 215 extends into the secondary inner groove 225, so that the first external thread 216 and the second internal thread 226 are threadedly engaged. Finally, bolts are locked into the three sets of main locking holes 212 and secondary locking holes 222 for fixation, thus completing the rapid assembly.

[0044] This invention provides a manufacturing process for an energy-saving motor shaft that is easy to assemble, comprising the following steps:

[0045] S1. Material selection: High-strength alloy steel, 40Cr, 42CrMo or carbon fiber reinforced metal matrix composite material can be selected, and the specific selection will be customized according to the actual situation. No restrictions are imposed here.

[0046] S2. Blank forming: The shaft blank is prepared by forging or precision casting to improve the material density and strength;

[0047] S3. Machining: The outer shape is machined by turning on a lathe, the shoulder is pre-machined, and then the thread is machined by tapping.

[0048] S4. Heat treatment: Use quenching and tempering, carburizing and quenching or induction hardening to improve the material's hardness and wear resistance.

[0049] S5. Coating treatment: Apply a low-friction nano-coating to the surface of the shaft to improve wear resistance and reduce energy consumption;

[0050] S7. Assembly: Connect the main body 1 of the rotating shaft and the external shaft 3 through the connecting structure 2 to complete the assembly.

[0051] Please see Figure 5 The tapping device of the present invention includes a linkage mechanism 4, which is mounted on a locking seat 5 and connected on the other side to a set of chuck feet 7 of a chuck 6. A tapping head 8 is mounted on the linkage mechanism 4, and the chuck 6 is provided with three sets of chuck feet 7. After adjusting the appropriate spacing, the workpiece a to be processed on the rotating shaft can be positioned. The tapping head 8 can then tap the threads of the workpiece a on the rotating shaft. It should be noted that the locking seat 5 is mounted on a movable component for adjusting the front-back and left-right positions of the locking seat 5, and the chuck 6 is mounted on a base with a motor drive for rotating the chuck 6. The movable component and the base with a motor drive are conventional technologies and will not be described in detail in this application.

[0052] Please see Figures 5-6 The linkage mechanism 4 of the present invention includes a fixed base 41, a first bevel gear 42, a linkage rod 43, a first adjustment component 44, a second bevel gear 45, a second adjustment component 46, a swing rod 47, a first push rod 48, and a second push rod 49. The front side of the fixed base 41 is mounted on a locking base 5. The first bevel gear 42 is rotatably connected to one side of the fixed base 41. The linkage rod 43 is rotatably connected to one side of the first bevel gear 42 extending downward from the plate. The other end of the linkage rod 43 is mounted on a set of chuck feet 7 of the chuck 6 through the first adjustment component 44. The upper part of the fixed base 41 is provided with a second bevel gear 45 and is rotatably connected by a shaft. The second bevel gear 45 meshes with the first bevel gear 42. A second adjustment component 46 is provided on one side of the upper part of the second bevel gear 45, and a swing rod 47 is rotatably connected to the second adjustment component 46. The lower part of the other end of the swing rod 47 is rotatably connected to a first push rod 48. The bottom of the first push rod 48 is fixedly sleeved on one end of the second push rod 49. The other end of the second push rod 49, which passes through the fixed base 41 and the first bevel gear 42, is connected to a tapping head 8.

[0053] Specifically, after the chuck 6 rotates, it drives the chuck foot 7 to rotate, and then the chuck foot 7 drives the connecting rod 43 to rotate. The connecting rod 43 synchronously drives the first bevel gear 42 to rotate on one side of the fixed seat 41. After meshing, the first bevel gear 42 synchronously drives the second bevel gear 45 to rotate on the upper part of the fixed seat 41. After the second bevel gear 45 rotates, it will drive one end of the swing rod 47 to move circumferentially. At the same time, the other end of the swing rod 47 is rotatably connected to the first push rod 48, and the first push rod 48 is connected to the second push rod 49. The second push rod 49 passes through the fixed seat 41 and the first bevel gear 42 and is positioned and guided, so that the swing rod 47 swings back and forth to drive the first push rod 48. Then the first push rod 48 drives the second push rod 49 to move telescopically in the middle of the fixed seat 41 and the first bevel gear 42, thereby driving the tapping head 8 to move back and forth, so as to perform thread tapping work on the workpiece a to be processed on the rotating shaft.

[0054] Please see Figures 7-8 The first adjustment component 44 of the present invention includes a base plate 441, a guide post 442, a guide sleeve 443, and a locking bolt 444. The base plate 441 is installed on the side of the locking foot 7, and the base plate 441 is provided with a guide post 442. The end of the connecting rod 43 is provided with a through hole and a guide sleeve 443. The guide post 442 slides through the through hole of the connecting rod 43 and the guide sleeve 443. One side of the guide sleeve 443 is provided with an opening, and a locking bolt 444 for locking the guide post 442 is provided in the opening.

[0055] Specifically, after the locking bolt 444 is loosened, the connecting rod 43 and the guide sleeve 443 can slide and adjust their positions on the guide post 442. After the position is adjusted, the locking bolt 444 can be used to lock and position the rod. The first adjustment component 44 is designed to facilitate the adjustment of the position of the connecting rod 43 and better adapt to the thread tapping work of the workpiece a to be processed on the rotating shaft.

[0056] Please see Figure 9 The second adjustment component 46 of the present invention includes a slider 461, a side fixing plate 462 and a threaded rod 463. The slider 461 is slidably disposed in a slide rail opened on one side of the upper part of the second bevel gear 45, and the side fixing plate 462 is installed on the outer side of the slide rail. The threaded rod 463 is provided through the side fixing plate 462, and the threaded rod 463 is threadedly connected to the threaded hole provided in the middle of the slider 461. The upper end of the slider 461 is rotatably connected to one end of the swing rod 47.

[0057] Specifically, by using a wrench or other tools to rotate the outer end of the threaded rod 463, the threaded rod 463 is rotated. After the threaded rod 463 rotates, it drives the slider 461 to slide in the slide rail opened on the upper part of the second bevel gear 45 through the thread, so as to adjust the position of the swing rod 47 and adjust the pushing distance of the second push rod 49.

[0058] This invention provides an energy-saving motor shaft that is easy to assemble and its manufacturing process. By incorporating a connection structure 2, the shaft body 1 and the external shaft 3 can be quickly and easily assembled, solving the problems of cumbersome and unstable connections in traditional methods. The connection structure 2 includes a main connection component 21 and a secondary connection component 22. The connection is secured by bolts after the connector 211 aligns with the locking hole of the connecting plate 221. Simultaneously, the sleeve 223 is embedded in the main inner groove 213, allowing the second external thread 224 to engage with the first internal thread 214. At the same time, the protrusion 215 extends into the secondary inner groove 225, allowing the first external thread 216 to engage with the second internal thread 226. Therefore, the connection between the shaft body 1 and the external shaft 3 via the main connection component 21 and the secondary connection component 22 is not only convenient to assemble but also tighter and more stable.

[0059] The manufacturing process of the motor shaft of this invention employs a tapping device for thread tapping, which enables faster and more efficient threading of the connecting structure 2, resulting in a tighter threaded connection between the main connecting component 21 and the auxiliary connecting component 22, and improving the stability of the motor shaft connection. The thread tapping device uses a linkage mechanism 4 to link the tapping head 8 with the chuck foot 7 of the chuck 6, thus eliminating the need for an additional motor to drive the tapping head 8 to move, achieving fast and efficient thread tapping and improving overall work efficiency.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for an energy-saving motor shaft that is easy to assemble, characterized in that: Includes the following steps: S1. Material Selection: High-strength alloy steel is selected; S2. Blank forming: The shaft blank is prepared by forging or precision casting. S3. Machining: The outer shape is machined by turning on a lathe, the shoulder is pre-machined, and then the thread is machined by tapping. S4. Heat treatment: Quenching and tempering, carburizing and quenching or induction hardening are adopted. S5. Coating treatment: Apply a low-friction nano-coating to the surface of the rotating shaft; S7. Assembly: Connect the main body (1) of the rotating shaft and the external shaft (3) through the connecting structure (2) to complete the assembly; The tapping device includes a linkage mechanism (4), which is mounted on a locking seat (5) and connected on the other side to a set of chuck feet (7) of a chuck (6). A tapping head (8) is mounted on the linkage mechanism (4). The linkage mechanism (4) includes a fixed base (41), a first bevel gear (42), a linkage rod (43), a first adjustment component (44), a second bevel gear (45), a second adjustment component (46), a swing rod (47), a first push rod (48), and a second push rod (49). The front side of the fixed base (41) is mounted on a locking base (5). The first bevel gear (42) is rotatably connected to one side of the fixed base (41). The linkage rod (43) is rotatably connected to one side of the first bevel gear (42) extending downward from the plate. The other end of the linkage rod (43) is mounted on a set of chuck feet (7) of the chuck (6) through the first adjustment component (44). On the fixed seat (41), a second bevel gear (45) is provided on the upper part and is rotatably connected by a shaft. The second bevel gear (45) meshes with the first bevel gear (42). A second adjustment component (46) is provided on one side of the upper part of the second bevel gear (45), and a swing rod (47) is rotatably connected on the second adjustment component (46). A first push rod (48) is rotatably connected to the lower part of the other end of the swing rod (47). The bottom of the first push rod (48) is fixedly sleeved on one end of the second push rod (49). The other end of the second push rod (49) that passes through the fixed seat (41) and the first bevel gear (42) is connected to a tapping head (8).

2. The manufacturing process of the energy-saving motor shaft that is easy to assemble according to claim 1, characterized in that: The first adjustment component (44) includes a base plate (441), a guide post (442), a guide sleeve (443), and a locking bolt (444). The base plate (441) is installed on the side of the foot (7), and the base plate (441) is provided with a guide post (442). The end of the connecting rod (43) is provided with a through hole and a guide sleeve (443). The guide post (442) slides through the through hole and the guide sleeve (443) of the connecting rod (43). The guide sleeve (443) is provided with an opening on one side, and a locking bolt (444) for locking the guide post (442) is provided in the opening.

3. The manufacturing process of an energy-saving motor shaft that is easy to assemble according to claim 1, characterized in that: The second adjustment component (46) includes a slider (461), a side plate (462), and a threaded rod (463). The slider (461) is slidably disposed in a slide rail opened on one side of the upper part of the second bevel gear (45), and a side plate (462) is installed on the outer side of the slide rail. A threaded rod (463) is provided through the side plate (462), and the threaded rod (463) is threadedly connected to the threaded hole provided in the middle of the slider (461). The upper end of the slider (461) is rotatably connected to one end of the swing rod (47).

4. The energy-saving motor shaft prepared according to the manufacturing process of the energy-saving motor shaft that is easy to assemble as described in claim 1, characterized in that: It includes a rotating shaft body (1), a connecting structure (2) and an external shaft (3), wherein the rotating shaft body (1) is connected to the external shaft (3) through the connecting structure (2); The connection structure (2) includes a main connection component (21) installed at the end of the rotating shaft body (1) and a secondary connection component (22) installed at the end of the external shaft (3). The main connection component (21) and the secondary connection component (22) are connected in cooperation.

5. The energy-saving motor shaft according to claim 4, characterized in that: The main connecting assembly (21) includes a connector (211), a main locking hole (212), a main inner groove (213), a first internal thread (214), a protrusion (215), and a first external thread (216). The connector (211) is integrally connected to the end of the rotating shaft body (1). The connector (211) has a main inner groove (213) in the middle and at least two sets of main locking holes (212) on the edge. The main inner groove (213) has a first internal thread (214) on the inner wall and a protrusion (215) in the middle. The protrusion (215) has a first external thread (216) on the outside.

6. The energy-saving motor shaft according to claim 5, characterized in that: The outer edge of the protrusion (215) is flush with the outer edge of the connector (211).

7. The energy-saving motor shaft according to claim 6, characterized in that: The secondary connecting assembly (22) includes a connecting plate (221), a secondary locking hole (222), a sleeve (223), a second external thread (224), a secondary inner groove (225), and a second internal thread (226). One side of the connecting plate (221) is integrally connected to the end of the external shaft (3). The connecting plate (221) is provided with a secondary locking hole (222) corresponding to the main locking hole (212). The other side of the connecting plate (221) is provided with a sleeve (223). The sleeve (223) is externally... The part is provided with a second external thread (224) and an internal secondary groove (225). The inner wall of the secondary inner groove (225) is provided with a second internal thread (226). The sleeve (223) and the main inner groove (213) of the connector (211) are embedded in each other, and the second external thread (224) is threaded in conjunction with the first internal thread (214). The protrusion (215) and the secondary inner groove (225) are embedded in each other, and the first external thread (216) is threaded in conjunction with the second internal thread (226).

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