A marine dual fuel engine connecting rod positioning device and method

Abstract

The present application relates to a kind of marine dual-fuel engine connecting rod positioning device and method, belong to marine engine connecting rod positioning processing technical field.The positioning device includes positioning table, the positioning table is equipped with clamping box, the positioning table both sides are equipped with clamping mechanism;One clamping mechanism output end is equipped with two first positioning claws symmetrically;The other clamping mechanism output end is equipped with two second positioning claws symmetrically.The present application is when rough machining, two clamping mechanisms are positioned by two groups of positioning claws to rod body and connecting rod cover respectively, when finishing, two clamping mechanisms cooperate two groups of positioning claws, lock rod body and connecting rod cover in clamping box, make the connecting hole on rod body and the connecting hole on connecting rod cover butt joint, make drilling device can be integrated processing to rod body and connecting rod cover, form two groups of height matching screw hole, so that the operation of marine dual-fuel engine is more reliable.

Description

Technical Field

[0001] This invention belongs to the field of marine engine connecting rod positioning and processing technology, specifically relating to a marine dual-fuel engine connecting rod positioning device and method. Background Technology

[0002] The connecting rod connects the piston and crankshaft, transmitting the pressure from the piston to the crankshaft, enabling the crankshaft to perform work. The connecting rod typically consists of a rod body and a connecting rod cap, both with threaded holes for threaded fasteners to assemble the rod body and connecting rod together. Marine dual-fuel engines operate on ships under complex conditions, including high temperature, high humidity, and vibration. These factors place higher demands on the durability and stability of engine components. Marine dual-fuel engines employ a dual-fuel supply system, allowing switching between different types of fuel when fuel availability is limited or specific needs require higher efficiency and more precise control.

[0003] Therefore, the connecting rods for marine dual-fuel engines require higher machining precision than those for ordinary engines to ensure reliable engine operation under harsh marine conditions. Currently, existing engine connecting rods involve separately positioning the rod body and connecting rod cap during the machining of the threaded holes. Machining the threaded holes on the rod body and connecting rod cap separately can easily lead to inconsistencies in the machining of the two sets of threaded holes. Process errors and mechanical instability can affect the matching degree between the threaded holes on the rod body and connecting rod cap. Especially in the case of marine dual-fuel engine connecting rods with higher requirements, this machining method can no longer meet the precision requirements. This can easily lead to a decrease in engine performance and may even damage engine components, affecting the normal operation of the ship. Summary of the Invention

[0004] The purpose of this invention is to provide a connecting rod positioning device and method for a marine dual-fuel engine in order to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] A connecting rod positioning device for a marine dual-fuel engine includes a rod body and a connecting rod cap. The positioning device comprises a positioning platform with a clamping box on the platform and clamping mechanisms on both sides. One clamping mechanism has two symmetrically arranged first positioning claws at its output end, which are used for rough machining and positioning of the rod body. The other clamping mechanism has two symmetrically arranged second positioning claws at its output end, which are used for rough machining and positioning of the connecting rod cap. During finish machining, the two clamping mechanisms use the first and second positioning claws to integrally assemble the rod body and connecting rod cap into the clamping box. The machining of the connecting rod's threaded holes is divided into rough machining and finish machining. During rough machining, the rod body and connecting rod cap are machined separately. During finish machining, the rod body and connecting rod cap are joined together for continuous, integral machining. The positioning process in the above machining process is divided into rough machining positioning and finish machining positioning. During rough machining positioning, the two clamping mechanisms clamp and position the rod body and connecting rod cap using the first and second positioning jaws, respectively, so that the drilling device can machine the connecting holes on the rod body and connecting rod cap. During finish machining positioning, the two clamping mechanisms use the first and second positioning jaws, respectively, to load the rod body and connecting rod cap into the clamping box, so that the connecting holes on the rod body align with the connecting holes on the connecting rod cap. After the rod body and connecting rod cap are loaded into the clamping box, the clamping box is closed, connecting the rod body and connecting rod cap as a single unit. This allows the drilling device to perform continuous, integrated machining of the rod body and connecting rod cap, forming two sets of threaded holes with a high degree of matching.

[0007] As a further optimization of the present invention, the positioning platform is provided with a drive component for opening or closing the clamping box, and the clamping box can lock the rod body and the connecting rod cover when closed.

[0008] As a further optimization of the present invention, the clamping box includes a box body and a box cover rotatably disposed on one side of the box body. The bottom wall of the box body protrudes upward to form a first stop and a second stop. The first stop is used to position the rod body, and the second stop is used to position the connecting rod cover, so that the rod body and the connecting rod cover are connected as one piece.

[0009] As a further optimization of the present invention, the box body is rotatably connected to the positioning platform above by a support frame, and when the drive component closes the clamping box, it can rotate the rod body to a vertical state.

[0010] As a further optimization of the present invention, one end of the rod body has a small end hole, and a large end hole is formed between the rod body and the connecting rod cover. The bottom wall of the box body is also provided with a first positioning cylinder and a second positioning cylinder corresponding to the small end hole and the large end hole, respectively.

[0011] As a further optimization of the present invention, the driving assembly includes a first motor fixed to the top of the positioning platform, a horizontal transmission rod rotatably mounted on the box body, a first gear fixed to one end of the transmission rod, a second gear fixed to the positioning platform, a third gear meshing between the first gear and the second gear, a first bevel gear fixed to the other end of the transmission rod, and a second bevel gear fixed to one side of the box cover. The axis of the second bevel gear is collinear with the rotation axis of the box cover, and the second bevel gear meshes with the first bevel gear. The output end of the first motor is fixedly connected to the box body, and the output end of the first motor is coaxially arranged with the second gear.

[0012] As a further optimization of the present invention, a bracket for supporting the box body is fixed on one side of the positioning platform.

[0013] As a further optimization of the present invention, the positioning device further includes a first support platform and a second support platform, wherein the first support platform is used to stop the first positioning claw and the second support platform is used to stop the second positioning claw.

[0014] As a further optimization of the present invention, both the first positioning claw and the second positioning claw have a receiving wall and an abutting wall, and the receiving wall is provided with a discharge hole. The receiving wall of the first positioning claw is used to cooperate with the first support platform to support the rod body, and the receiving wall of the second positioning claw is used to cooperate with the second support platform to support the connecting rod cover. The abutting wall of the first positioning claw is used to abut the rod body against the first support platform, and the abutting wall of the second positioning claw is used to abut the connecting rod cover against the second support platform.

[0015] A method for positioning a connecting rod in a marine dual-fuel engine includes the following steps:

[0016] S1. The two clamping mechanisms clamp and position the rod body and the connecting rod cover respectively through the first positioning claw and the second positioning claw. Then, the rod body and the connecting rod cover are rough machined to form connecting holes on both sides of the rod body and the connecting rod cover.

[0017] S2. After rough machining is completed, the two clamping mechanisms use the first positioning claw and the second positioning claw to load the rod body and the connecting rod cover into the clamping box, so that the connecting hole on the rod body aligns with the connecting hole on the connecting rod cover.

[0018] S3. After the rod body and connecting rod cap are installed into the clamping box, the clamping box is closed. Then, the connecting holes on the rod body and connecting rod cap are machined into threaded holes, and the inner diameter of the threaded holes is larger than the inner diameter of the connecting holes.

[0019] The beneficial effects of this invention are as follows:

[0020] 1) During rough machining positioning, the two clamping mechanisms clamp and position the rod body and connecting rod cover respectively through two sets of positioning claws to facilitate the machining of connecting holes. During fine machining positioning, the two clamping mechanisms cooperate with the two sets of positioning claws to lock the rod body and connecting rod cover in the clamping box, so that the connecting holes on the rod body align with the connecting holes on the connecting rod cover, connecting the rod body and connecting rod cover into one piece. This allows the drilling device to perform continuous machining of the rod body and connecting rod cover as a whole, forming two sets of screw holes with a high degree of matching and high machining accuracy, ensuring that the engine can operate stably for a long time.

[0021] 2) During the closing process of the clamping box by the drive assembly of the present invention, the first motor drives the box body to rotate. While the box body rotates, the first gear and the third gear rotate around the second gear fixed on the positioning table. At the same time, the third gear rotates under the action of the second gear and drives the transmission rod, the first bevel gear and the second bevel gear to rotate through the first gear, thereby closing the box cover. The connecting rod is in a vertical state. The drilling device can perform integrated continuous processing on the rod body and the connecting rod cover from above, forming two sets of screw holes with a high degree of matching. The cutting tool of the drilling device is vertically downward and is not easy to bend or deform. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the clamping box of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of the first positioning claw of the present invention;

[0025] Figure 4 This is a schematic diagram of the structure of the second positioning claw of the present invention;

[0026] Figure 5 This is a schematic diagram of the working state of the connecting rod during assembly of the present invention;

[0027] Figure 6 This is a schematic diagram of the structure of the first support platform of the present invention;

[0028] Figure 7 This is a schematic diagram of the structure of the second support platform of the present invention;

[0029] Figure 8 This is a schematic diagram of the fixture of the present invention.

[0030] In the diagram: 1. Positioning platform; 2. Clamping box; 3. Clamping mechanism; 4. First positioning claw; 5. Second positioning claw; 6. Drive assembly; 7. Bracket; 8. First support platform; 9. Second support platform; 21. Box body; 22. Box cover; 23. First stop; 24. Second stop; 25. First positioning cylinder; 26. Second positioning cylinder; 31. Robotic arm; 32. Plate; 33. Clamping block; 34. Second motor; 35. Swing arm; 36. Rotary arm; 61. First motor; 62. Transmission rod; 63. First gear; 64. Second gear; 65. Third gear; 66. First bevel gear; 67. Second bevel gear; H. Unloading hole; Rb. Rod body; Rc. Connecting rod cover. Detailed Implementation

[0031] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0032] First Embodiment

[0033] like Figure 1-5 As shown, this embodiment relates to a marine dual-fuel engine connecting rod positioning device. The marine dual-fuel engine connecting rod has a rod body Rb and a connecting rod cap Rc. The positioning device includes a positioning platform 1, a clamping box 2 on the positioning platform 1, clamping mechanisms 3 on both sides of the positioning platform 1, and two drilling devices on both sides of the positioning platform 1. The two drilling devices are respectively used to process connecting holes on the rod body Rb and the connecting rod cap Rc. Another drilling device is provided between the two drilling devices near the positioning platform 1 to process the connecting hole into a screw hole.

[0034] One clamping mechanism 3 has two symmetrically arranged first positioning claws 4 at its output end. This clamping mechanism 3 uses the first positioning claws 4 to perform rough machining positioning of the rod body Rb. The other clamping mechanism 3 has two symmetrically arranged second positioning claws 5 at its output end. This clamping mechanism 3 uses the second positioning claws 5 to perform rough machining positioning of the connecting rod cap Rc. During finish machining, the two clamping mechanisms 3 use the first positioning claws 4 and the second positioning claws 5 to integrally assemble the rod body Rb and the connecting rod cap Rc into the clamping box 2. The clamping box 2 includes a box body 21 and a box cover 22 rotatably disposed on one side of the box body 21. The bottom wall of the box body 21 protrudes upward to form a first stop 23 and a second stop 24. The first stop 23 is used to position the rod body Rb, and the second stop 24 is used to position the connecting rod cap Rc, so that the rod body Rb and the connecting rod cap Rc are integrated. The positioning table 1 is provided with a drive assembly 6 for opening or closing the clamping box 2. When the clamping box 2 is closed, it can lock the rod body Rb and the connecting rod cap Rc. The box 21 is rotatably connected to the positioning platform 1 via a support frame.

[0035] In this embodiment, the machining of the connecting rod's screw holes is divided into rough machining and finish machining. During rough machining, the rod body Rb and the connecting rod cap Rc are machined separately. During finish machining, the rod body Rb and the connecting rod cap Rc are joined together for continuous, integrated machining. The positioning steps in the above machining process are divided into rough machining positioning and finish machining positioning.

[0036] During rough machining positioning, the two clamping mechanisms 3 respectively use the first positioning claw 4 and the second positioning claw 5 to clamp the rod body Rb and the connecting rod cap Rc from the two feed conveyor belts, and position the rod body Rb and the connecting rod cap Rc to the rough machining working position so that the drilling device can machine the connecting holes on the rod body Rb and the connecting rod cap Rc. During finish machining positioning, the two clamping mechanisms 3 respectively use the first positioning claw 4 and the second positioning claw 5 to load the rod body Rb and the connecting rod cap Rc into the clamping box 2, so that the connecting hole on the rod body Rb aligns with the connecting hole on the connecting rod cap Rc.

[0037] After the rod body Rb and connecting rod cap Rc are installed into the clamping box 2, the large end of the rod body Rb and the connecting rod cap Rc are surrounded by two first stop members 23 and two second stop members 24. The inner edge shapes of the first stop members 23 and the second stop members 24 are the same as the outer edge shapes of the rod body Rb and the connecting rod cap Rc, respectively. When the clamping box 2 is closed, the rod body Rb and the connecting rod cap Rc are connected as one unit. The drive assembly 6 closes the clamping box 2 while rotating the box body 21, so that the rod body Rb inside the box body 21 is in a vertical state. The drilling device can perform continuous one-piece machining of the rod body Rb and the connecting rod cap Rc from above, forming two sets of screw holes with a high degree of matching. The cutting tool of the drilling device is vertically downward and is not easily bent or deformed.

[0038] Specifically, such as Figure 2 As shown, the drive assembly 6 includes a first motor 61 fixed to the top of the positioning platform 1, a horizontal transmission rod 62 rotatably mounted above one end of the box body 21, a first gear 63 fixed to one end of the transmission rod 62, a second gear 64 fixed to the positioning platform 1, a third gear 65 meshing between the first gear 63 and the second gear 64, a first bevel gear 66 fixed to the other end of the transmission rod 62, and a second bevel gear 67 fixed to one side of the box cover 22. The axis of the second bevel gear 67 is collinear with the rotation axis of the box cover 22. The second bevel gear 67 meshes with the first bevel gear 66. The output end of the first motor 61 is fixedly connected to the box body 21, and the output end of the first motor 61 is coaxially arranged with the second gear 64. The output end of the first motor 61 can rotate relative to the second gear 64. The third gear 65 is rotatably mounted on the side wall of the box body 21 via a rotating shaft. A hinge is provided between the box cover 22 and the box body 21. The hinge is rotatably connected to the box body 21 and fixedly connected to the side of the box cover 22. The box cover 22 is fixed to the second bevel gear 67 via the hinge.

[0039] During the closing of the clamping box 2 by the drive assembly 6, the output end of the first motor 61 drives the box body 21 to rotate 90°, making the connecting rod inside the clamping box 2 vertical. Simultaneously, the first gear 63 and the third gear 65 rotate around the second gear 64 fixed on the positioning table 1. At the same time, the third gear 65 rotates under the action of the second gear 64, and through the first gear 63, drives the transmission rod 62 and the first bevel gear 66 to rotate. The first bevel gear 66 meshes with the second bevel gear 67, thereby driving the box cover 22 to rotate 180°, closing the clamping box 2. At this time, a drilling device near the positioning table 1 processes the connecting hole into a threaded hole. A thread milling cutter is installed at the output end of this drilling device near the positioning table 1 to process the thread groove. After the screw hole is machined, the first motor 61 rotates in the reverse direction, thereby causing the drive assembly 6 to open and reset the clamping box 2. A bracket 7 for supporting the box body is fixed on one side of the positioning table 1. When the clamping box 2 is reset, it rotates 90° in the reverse direction. At this time, the bottom of the box body 21 is in contact with the top of the bracket 7. The two clamping mechanisms 3, together with the first positioning claw 4 and the second positioning claw 5, take out the rod body Rb and the connecting rod cover Rc of the connecting rod and place them on the discharge conveyor belt.

[0040] Further, please refer to Figure 6 and Figure 7 The positioning device also includes a first support platform 8 and a second support platform 9. The first support platform 8 is used to stop the first positioning claw 4, and the second support platform 9 is used to stop the second positioning claw 5. Both the first positioning claw 4 and the second positioning claw 5 have a receiving wall and an abutting wall, and the receiving wall is provided with a discharge hole H. The receiving wall of the first positioning claw 4 is used to cooperate with the first support platform 8 to support the rod body Rb, and the receiving wall of the second positioning claw 5 is used to cooperate with the second support platform 9 to support the connecting rod cover Rc. The abutting wall of the first positioning claw 4 is used to abut the rod body Rb against the first support platform 8, and the abutting wall of the second positioning claw 5 is used to abut the connecting rod cover Rc against the second support platform 9. During rough machining, a clamping mechanism 3 uses a first positioning claw 4 to press the rod body Rb against the first support platform 8. At this time, the first positioning claw 4 rests on the bottom wall of the first support platform 8. Another clamping mechanism 3 uses a second positioning claw 5 to press the connecting rod cap Rc against the second support platform 9. At this time, the second positioning claw 5 rests on the bottom wall of the second support platform 9. The first support platform 8 and the second support platform 9 can improve the accuracy of the rough machining of the connecting rod.

[0041] In addition, such as Figure 8As shown, the two clamping mechanisms 3 have the same structure. Each clamping mechanism 3 consists of a robotic arm 31 and a clamp fixed to the output end of the robotic arm 31. The clamp includes a plate 32 fixed to the output end of the robotic arm 31 and two clamping blocks 33 slidably disposed on the plate 32, as well as a driving component for driving the two clamping blocks 33 to move in opposite directions. The driving component specifically includes a second motor 34 fixed to the plate 32, a swing arm 35 fixed to the output end of the second motor 34, and two cantilever arms 36 rotatably disposed between the swing arm 35 and the two clamping blocks 33. When clamping the connecting rod, the second motor 34 drives the swing arm 35 to rotate, and the swing arm 35 pulls the two clamping blocks 33 toward each other through the two cantilever arms 36 to achieve the clamping operation. In addition, one end of the rod body Rb has a small end hole, and a large end hole is formed between the rod body Rb and the connecting rod cap Rc. The bottom wall of the housing 21 is also provided with a first positioning cylinder 25 and a second positioning cylinder 26 corresponding to the small end hole and the large end hole, respectively. The outer edges of the first positioning cylinder 25 and the second positioning cylinder 26 are both chamfered. The positioning effect of the rod body Rb and the connecting rod cap Rc is enhanced by the first positioning cylinder 25 and the second positioning cylinder 26 in conjunction with the first stop 23 and the second stop 24.

[0042] Second Embodiment

[0043] This embodiment relates to a method for positioning a connecting rod of a marine dual-fuel engine, applicable to the marine dual-fuel engine connecting rod positioning device in the first embodiment, and includes the following steps:

[0044] S1. The two clamping mechanisms 3 clamp and position the rod body Rb and the connecting rod cap Rc respectively through the first positioning claw 4 and the second positioning claw 5. Then, the two drilling devices perform rough machining on the rod body Rb and the connecting rod cap Rc respectively, so that connecting holes are formed on both sides of the rod body Rb and the connecting rod cap Rc.

[0045] S2. After rough machining is completed, the two clamping mechanisms 3 respectively use the first positioning claw 4 and the second positioning claw 5 to load the rod body Rb and the connecting rod cover Rc into the clamping box 2, so that the connecting hole on the rod body Rb is aligned with the connecting hole on the connecting rod cover Rc.

[0046] S3. After the rod body Rb and connecting rod cap Rc are installed into the clamping box 2, the drive assembly 6 closes the clamping box 2 and simultaneously rotates the clamping box 2 as a whole by 90°. Then, the connecting holes on the rod body Rb and connecting rod cap Rc are machined into screw holes by another drilling device, and the inner diameter of the screw hole is larger than the inner diameter of the connecting hole.

[0047] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A connecting rod positioning device for a marine dual-fuel engine, the connecting rod of the marine dual-fuel engine having a rod body and a connecting rod cap, and the positioning device including a positioning platform (1), characterized in that: The positioning platform (1) is provided with a clamping box (2), and clamping mechanisms (3) are provided on both sides of the positioning platform (1). One clamping mechanism (3) has two first positioning claws (4) symmetrically arranged at its output end. The clamping mechanism (3) uses the first positioning claws (4) to perform rough machining and positioning of the rod body. The other clamping mechanism (3) has two second positioning claws (5) symmetrically arranged at its output end. The clamping mechanism (3) uses the second positioning claws (5) to perform rough machining and positioning of the connecting rod cover. During fine machining, the two clamping mechanisms (3) use the first positioning claws (4) and the second positioning claws (5) to assemble the rod body and the connecting rod cover into a single unit in the clamping box (2). The positioning platform (1) is provided with a drive assembly (6) for opening or closing the clamping box (2), which can lock the rod body and the connecting rod cover when the clamping box (2) is closed; The clamping box (2) includes a box body (21) and a box cover (22) rotatably disposed on one side of the box body (21). The bottom wall of the box body (21) protrudes upward to form a first stop (23) and a second stop (24). The first stop (23) is used to position the rod body, and the second stop (24) is used to position the connecting rod cover so that the rod body and the connecting rod cover are connected as one piece. The box (21) is rotatably connected to the positioning platform (1) via a support frame. When the drive assembly (6) closes the clamping box (2), it can rotate the rod body to a vertical state. The drive assembly (6) includes a first motor (61) fixed to the top of the positioning platform (1), a horizontal transmission rod (62) rotatably mounted on the box body (21), a first gear (63) fixed to one end of the transmission rod (62), a second gear (64) fixed to the positioning platform (1), a third gear (65) meshing between the first gear (63) and the second gear (64), a first bevel gear (66) fixed to the other end of the transmission rod (62), and a second bevel gear (67) fixed to one side of the box cover (22). The axis of the second bevel gear (67) is collinear with the rotation axis of the box cover (22), and the second bevel gear (67) meshes with the first bevel gear (66). The output end of the first motor (61) is fixedly connected to the box body (21), and the output end of the first motor (61) is coaxially arranged with the second gear (64).

2. The marine dual-fuel engine connecting rod positioning device according to claim 1, characterized in that: The rod has a small end hole at one end, and a large end hole is formed between the rod and the connecting rod cover. The bottom wall of the box (21) is provided with a first positioning cylinder (25) corresponding to the small end hole and a second positioning cylinder (26) corresponding to the large end hole.

3. The marine dual-fuel engine connecting rod positioning device according to claim 1, characterized in that: The positioning platform (1) is fixed on one side with a bracket (7) for supporting the box body (21).

4. The marine dual-fuel engine connecting rod positioning device according to claim 1, characterized in that: The positioning device also includes a first support platform (8) and a second support platform (9), the first support platform (8) being used to stop the first positioning claw (4) and the second support platform (9) being used to stop the second positioning claw (5).

5. The marine dual-fuel engine connecting rod positioning device according to claim 4, characterized in that: The first positioning claw (4) and the second positioning claw (5) both have a receiving wall and an abutting wall, and the receiving wall is provided with a discharge hole. The receiving wall of the first positioning claw (4) is used to cooperate with the first support platform (8) to support the rod body, and the receiving wall of the second positioning claw (5) is used to cooperate with the second support platform (9) to support the connecting rod cover. The abutting wall of the first positioning claw (4) is used to abut the rod body against the first support platform (8), and the abutting wall of the second positioning claw (5) is used to abut the connecting rod cover against the second support platform (9).

6. A method for positioning a connecting rod in a marine dual-fuel engine, characterized in that, The marine dual-fuel engine connecting rod positioning device according to any one of claims 1-5 includes the following steps: S1. One clamping mechanism (3) clamps and positions the rod body through the first positioning claw (4), and another clamping mechanism (3) clamps and positions the connecting rod cover through the second positioning claw (5). Then, the rod body and the connecting rod cover are rough machined so that connecting holes are formed on both sides of the rod body and the connecting rod cover. S2. After rough machining, the two clamping mechanisms (3) respectively use the first positioning claw (4) and the second positioning claw (5) to put the rod body and the connecting rod cover into the clamping box (2) so that the connecting hole on the rod body is connected to the connecting hole on the connecting rod cover. S3. After the rod body and connecting rod cap are installed into the clamping box (2), the clamping box (2) is closed. Then the connecting holes on the rod body and connecting rod cap are machined into screw holes, and the inner diameter of the screw hole is larger than the inner diameter of the connecting hole.

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