Method for machining a connecting rod with a reference unification

Abstract

The application provides a reference-unified connecting rod machining process method. In the initial machining of the connecting rod, a process positioning hole is machined on the rod body and the rod cover end face, so that the process positioning hole penetrates the whole machining process of the connecting rod, the reference is unified from the front to the back of each process, the positioning error of each process is reduced, the machining precision of the part is improved, the positioning is accurate, convenient and fast, the positioning error is reduced, the machining precision is improved, the quality is guaranteed and the production efficiency is improved, the positioning reference is unified, the positioning error between each process is avoided, the precision requirement of the big head hole and the small head hole, the rod cover joint surface and the convex shoulder surface as the positioning reference is reduced, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of diesel engine connecting rod processing technology, specifically relating to a connecting rod processing method with unified reference. Background Technology

[0002] Because diesel engine connecting rods require high machining precision, are prone to deformation, have a long process flow, and have close connections between processes, the machining precision of the preceding process has a significant impact on the machining precision of the following process. Furthermore, due to the continuous changes in process benchmarks, the precision requirements of each process are also relatively high, making it difficult to control the machining precision of the connecting rods.

[0003] Currently, traditional processing methods for connecting rods, such as Figure 6 As shown, during the machining of the rod body, the process references before the semi-finish boring of the rod body hole are the large and small end faces and the large and small end holes. The large and small end holes, serving as positioning references, must be machined to IT7 level to ensure positioning accuracy. The semi-finish boring of the rod body hole also uses movable positioning pins to position the rod body within the large and small end holes. After accurate positioning and clamping of the rod body, the positioning pins are removed to machine the large and small end holes. The machined large and small end holes then serve as positioning references for machining the rod body mating surface and bolt holes, and also as positioning references for the final finish boring of the large and small end holes. During finish boring, movable positioning pins are used to position the rod body within the large and small end holes. After accurate positioning, the positioning pins are removed to machine the large and small end holes. From the positioning of the rod body, it can be seen that the large and small end holes used for positioning undergo three stages. In the semi-finish boring stage, before, after, and after finish boring, positioning errors caused by datum reversal affect the positional accuracy of bolt holes, large-end holes, small-end holes, and the outer diameter. For the machining of the rod cap, the positioning datum is the rod cap end face, large-end hole, mating surface, and shoulder surface. During semi-finish boring of the rod cap hole, the rod cap end face, large-end hole, and shoulder surface are used for positioning. A movable locating pin is used for positioning within the large-end hole; after accurate positioning and clamping the connecting rod, the locating pin is removed. In the milling of the rod cap mating surface for bolt hole machining, the positioning datum is the rod cap end face, the large-end hole after semi-finish boring, and the shoulder surface. However, machining the rod cap shoulder surface uses the mating surface as the datum. This mutual datum-based approach leads to accumulated errors, resulting in poor perpendicularity between the mating surface and the side surface, thus failing to guarantee the positional accuracy of the bolt holes and pin holes relative to the side surface on the mating surface. Therefore, improvements are necessary to address these issues. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a connecting rod machining process with unified datum. During the initial machining of the connecting rod, process positioning holes are machined on the end faces of the rod body and the rod cap, allowing these holes to run through the entire machining process. This ensures unified datum across all processes, reducing positioning errors and improving part machining accuracy. Accurate, convenient, and quick positioning reduces positioning errors and improves machining precision, thereby achieving the goals of ensuring quality and improving production efficiency. Unifying the positioning datum avoids positioning errors between processes and reduces the accuracy requirements for the large and small end holes, the rod cap mating surface, and the shoulder surface, which serve as positioning datums, thus lowering production costs.

[0005] The technical solution adopted in this invention is a standardized connecting rod processing method, comprising the following steps:

[0006] 1) Precision milling of the upper end face: After positioning and fixing the connecting rod with the lower end face and the large end hole and small end hole of the connecting rod as positioning references, precision mill the upper end face of the connecting rod.

[0007] 2) Precision milling of the lower end face and machining of reference holes: Using the upper end face of the connecting rod after precision milling, as well as the large end hole and small end hole of the connecting rod as positioning references, after positioning and fixing the connecting rod, precision mill the upper end face of the connecting rod, and machine multiple process positioning holes distributed on the rod body and rod cap as reference holes on the upper end face of the connecting rod.

[0008] 3) Machining process holes: After positioning and fixing the connecting rod using a connecting rod fixture that is adapted to the lower end face of the connecting rod and the two process positioning holes located on the rod body, a shoulder surface and a process hole are machined on the large end and small end face of the connecting rod respectively. After machining is completed, the connecting rod fixture is removed.

[0009] 4) Machining the arc surfaces: After fixing the connecting rod with the small end and the shoulder surface of the large end as positioning references, machine the two arc surfaces of the connecting rod.

[0010] 5) Cutting: Cut the connecting rod along the cleaving line to form the shaft and cap;

[0011] 6) Drilling deep holes: After positioning and fixing the rod body using a connecting rod fixture that matches the process positioning holes at the lower end face and both ends of the rod body, deep holes are machined on the rod body along its mating surface.

[0012] 7) Semi-finish boring of the shaft: Semi-finish boring of the shaft hole on the shaft;

[0013] 8) Milling the rod body mating surface: After milling the rod body mating surface according to the drawing requirements, machine bolt holes on the rod body mating surface, and then remove the connecting rod fixture;

[0014] 9) Semi-finish boring of the rod cap hole: After the rod cap is positioned and fixed by a rod cap fixture that is adapted to the lower end face of the rod cap and the two process positioning holes on the rod cap, the rod cap hole is semi-finish bored.

[0015] 10) Milling the rod cap mating surface: After milling the rod cap mating surface according to the drawing requirements, machine the screw holes on the rod cap mating surface that correspond to the bolt hole positions on the rod body mating surface;

[0016] 11) Milling the shoulder surface of the rod cap: After milling the shoulder surface on the end face of the rod cap, remove the rod cap fixture;

[0017] 12) Assembly: Align the mating surfaces of the rod cap and the rod body, and use bolts that fit the bolt holes on the mating surface of the rod body and the screw holes on the rod cap, as well as nuts that fit the bolts, to fix the rod cap and the rod body together as one unit;

[0018] 13) Precision boring: After positioning and fixing the assembled connecting rod using a connecting rod fixture that matches the process positioning holes on the upper end face and both ends of the rod, precision boring is performed on the large end hole and small end hole on the connecting rod.

[0019] The connecting rod clamp includes a base body. At the same height on both ends of the upper surface of the base body, there are three support pins arranged in a triangle. The three support pins contact the lower end surfaces of the small end and the two sides of the large end hole of the connecting rod, respectively. The base body is fixed with cylindrical pins and rhomboid pins that are adapted to and connected to two process positioning holes on the rod body. The connecting rod is pressed and fixed by multiple sets of parallel pressure plates fixed to the upper surface of the base body.

[0020] Furthermore, the parallel pressure plates are provided in three sets and distributed on both sides of the small end and the large end of the connecting rod.

[0021] Furthermore, the base body has a T-shaped structure with the right end wider than the left end, and the larger end of the rod is located at the right end of the base body.

[0022] Furthermore, the rod cap clamp includes a base body two. The upper end face of the base body two has three support pins two distributed at equal height in a triangular shape, which are used to contact the lower end face of the rod cap and support the rod cap. The upper end face of the base body two is fixed with cylindrical pins two and rhomboid pins two that are respectively adapted to two process positioning holes on the rod cap. The rod cap is pressed and fixed to the base body two by a pressure plate located at half of the large end hole on the rod cap and fixed to the base body two by long bolts.

[0023] Advantages of this invention compared to existing technologies:

[0024] 1. In the initial machining of the connecting rod, this technical solution uses process positioning holes machined on the end faces of the rod body and the rod cap. These process positioning holes run through the entire machining process of the connecting rod, ensuring that the reference datum is consistent from front to back, thereby reducing positioning errors in each process and improving the machining accuracy of the parts.

[0025] 2. This technical solution unifies the positioning benchmark, avoids positioning errors between processes, and reduces the accuracy requirements for the large and small end holes, the rod cap mating surface, and the shoulder surface that serve as the positioning benchmark, thereby reducing production costs.

[0026] 3. This technical solution provides accurate, convenient, and quick positioning, reduces positioning errors, and improves processing accuracy, thereby achieving the goals of ensuring quality and improving production efficiency;

[0027] 4. This technical solution uses the same set of fixtures for multiple processes, which reduces the workload of tooling design and saves production cost. Attached Figure Description

[0028] Figure 1 This is a flowchart of the connecting rod processing technology of the present invention;

[0029] Figure 2 This is a front view of the connecting rod clamp structure of the present invention;

[0030] Figure 3 This is a top view of the connecting rod clamp structure of the present invention;

[0031] Figure 4 This is a front view of the rod cap clamp structure of the present invention;

[0032] Figure 5 This is a top view of the rod cap clamp structure of the present invention;

[0033] Figure 6 This is a flowchart of the existing connecting rod manufacturing process. Detailed Implementation

[0034] The following will be based on embodiments of the present invention. Figure 1-5 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that, unless otherwise stated herein, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0037] A standardized and consistent linkage manufacturing process, such as Figure 1 As shown, it includes the following steps:

[0038] 1) Precision milling of the upper end face: After positioning and fixing the connecting rod 1 with the lower end face of the connecting rod 1 and the large end hole 2 and small end hole 3 of the connecting rod 1 as positioning references, precision mill the upper end face of the connecting rod 1.

[0039] 2) Precision milling of the lower end face and machining of reference holes: Using the upper end face of the connecting rod 1 after precision milling and the large end hole 2 and small end hole 3 of the connecting rod 1 as positioning references, after positioning and fixing the connecting rod 1, precision milling of the upper end face of the connecting rod 1, and machining of multiple process positioning holes 4 distributed on the rod body 1-1 and the rod cover 1-2 as reference holes on the upper end face of the connecting rod 1.

[0040] 3) Machining process holes: After positioning and fixing the connecting rod 1 using a connecting rod fixture that is adapted to connect the lower end face of the connecting rod 1 and the two process positioning holes 4 located on the rod body 1-1, the shoulder surface 6 and the process hole 5 are machined on the large end and small end face of the connecting rod 1 respectively. After machining, the connecting rod fixture is removed.

[0041] 4) Machining the arc surfaces: After fixing the connecting rod 1 with the small end and the shoulder surface 6 of the large end as positioning references, machine the two arc surfaces of the connecting rod 1.

[0042] 5) Cutting: Cut the connecting rod 1 along the cleaving line to form the rod body 1-1 and the rod cap 1-2;

[0043] 6) Drilling deep holes: After fixing the rod body 1-1 with a connecting rod fixture that is compatible with the process positioning holes 4 at both ends of the rod body 1-1, drill deep holes 7 on the rod body 1-1 along its mating surface.

[0044] 7) Semi-finish boring of the shaft hole: Semi-finish boring of the shaft hole on shaft 1-1;

[0045] 8) Milling the rod body mating surface: After milling the rod body 1-1 mating surface according to the drawing requirements, machine bolt holes on the rod body 1-1 mating surface, and then remove the connecting rod fixture;

[0046] 9) Semi-finish boring of the rod cap hole: After the rod cap 1-2 is positioned and fixed by the rod cap clamp that is adapted to the lower end face of the rod cap 1-2 and the two process positioning holes 4 located on the rod cap 1-2, the rod cap hole is semi-finish bored.

[0047] 10) Milling the mating surface of the rod cap: After milling the mating surface of the rod cap 1-2 according to the drawing requirements, machine the screw holes on the mating surface of the rod cap 1-2 that correspond to the positions of the bolt holes on the mating surface of the rod body 1-1;

[0048] 11) Milling the shoulder surface of the rod cap: After milling the shoulder surface 6 on the end face of the rod cap 1-2, remove the rod cap fixture;

[0049] 12) Assembly: Align the mating surfaces of the rod cap 1-2 and the rod body 1-1, and fix the rod cap 1-2 and the rod body 1-1 into one piece by the bolt holes on the mating surface of the rod body 1-1 and the screw holes on the rod cap 1-2, and the nuts connected to the screws.

[0050] 13) Precision boring: After positioning and fixing the assembled connecting rod 1 with the process positioning holes 4 on the upper end face of the rod body 1-1 and both ends of the rod body 1-1, precision boring is performed on the large end hole 2 and the small end hole 3 on the connecting rod 1.

[0051] In the above-described processing procedure, during the initial processing of connecting rod 1, process positioning holes 4 are machined on the end faces of rod body 1-1 and rod cap 1-2. These process positioning holes 4 are made to run through the entire processing of the connecting rod, ensuring that the datum is consistent across all processes from beginning to end. This reduces positioning errors between processes and improves the machining accuracy of the parts. By unifying the positioning datum, positioning errors between processes are avoided, and the accuracy requirements for the large end hole 2 and small end hole 3, the mating surface of rod cap 1-2, and the shoulder surface 6, which serve as positioning datums, are reduced, thus lowering production costs. Accurate, convenient, and quick positioning reduces positioning errors and improves machining accuracy, thereby achieving the goals of ensuring quality and improving production efficiency.

[0052] like Figure 2-3As shown, the specific structure of the connecting rod clamp is as follows: The connecting rod clamp includes a base body 8. At the same height on both ends of the upper surface of the base body 8, there are three support pins 9 arranged in a triangular pattern. The three support pins 9 are respectively in contact with the middle of the small end of the connecting rod 1 and the lower end surfaces on both sides of the large end hole 2. The base body 8 is fixed with cylindrical pins 10 and rhomboid pins 11 that are adapted to and connected to the two process positioning holes 4 on the rod body 1-1. The connecting rod 1 is pressed and fixed by multiple sets of parallel pressure plates 12 fixed to the upper surface of the base body 8. Specifically, there are three sets of parallel pressure plates 12, which are distributed on both sides of the small end and the large end of the connecting rod 1. The base body 8 has a T-shaped structure with the width of the right end being greater than the width of the left end, and the large end of the rod body 1-1 is located at the right end of the base body 8.

[0053] In the above structure, the deep hole drilling process, the semi-finish boring process, the milling of the rod body mating surface process, and the finish boring process are all positioned using the large and small end faces of the connecting rod 1 and the process positioning hole 4. It is a one-face two-pin positioning method. Furthermore, the semi-finish boring process, the milling of the rod body mating surface process, and the finish boring process all use the same set of fixtures, resulting in smaller positioning errors between processes. The large and small end face positioning restricts the three degrees of freedom of the connecting rod 1, including two rotational degrees of freedom and one translational degree of freedom. A cylindrical pin-10 restricts two translational degrees of freedom, and a diamond pin-11 restricts one rotational degree of freedom. All six degrees of freedom are restricted, and the connecting rod 1 is accurately positioned on the connecting rod fixture.

[0054] like Figure 4-5 As shown, the specific structure of the rod cover clamp is as follows: The rod cover clamp includes a base body 2 13. The upper end face of the base body 2 13 has three support pins 2 14 distributed at equal height in a triangular shape, which are used to contact the lower end face of the rod cover 1-2 and support the rod cover 1-2. The upper end face of the base body 2 13 is fixed with cylindrical pins 2 15 and rhomboid pins 2 16, which are respectively adapted to the two process positioning holes 4 on the rod cover 1-2. The rod cover 1-2 is pressed and fixed to the base body 2 13 by a pressure plate 17 located at half of the large end hole 2 on the rod cover 1-2 and fixed to the base body 2 13 by long bolts.

[0055] For the rod cap 1-2 processes, such as the semi-precision boring of the rod cap hole, the milling of the rod cap mating surface, and the milling of the rod cap shoulder surface, all are positioned using the end face of the rod cap 1-2 and the process positioning hole 4. It is a one-face two-pin positioning method. The semi-precision boring of the rod cap hole, the milling of the rod cap mating surface, and the milling of the rod cap shoulder surface use the same set of fixtures, which reduces the positioning error between processes. The end face positioning restricts the three degrees of freedom of the rod cap 1-2, including two rotational degrees of freedom and one translational degree of freedom. One cylindrical pin 15 restricts two translational degrees of freedom, and one rhomboid pin 16 restricts one rotational degree of freedom. All six degrees of freedom are restricted, which makes the rod cap 1-2 accurately positioned on the rod cap fixture.

[0056] This technical solution replaces the positioning function of the large end hole 2 and small end hole 3 of the connecting rod 1, the mating surface of the rod cap 1-2, and the shoulder surface 6 with the process positioning hole 4. This reduces the machining accuracy requirements of the large end hole 2 and small end hole 3, the mating surface of the rod cap 1-2, and the shoulder surface 6, making machining easier, more economical, and allowing multiple processes to share the same set of fixtures, reducing the workload of tooling design and saving production costs.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A standardized connecting rod machining process, characterized in that... Includes the following steps: 1) Precision milling of the upper end face: After positioning and fixing the connecting rod (1) with the lower end face of the connecting rod (1) and the large end hole (2) and small end hole (3) of the connecting rod (1) as positioning references, precision mill the upper end face of the connecting rod (1); 2) Precision milling of the lower end face and machining of reference holes: Using the upper end face of the connecting rod (1) after precision milling and the large end hole (2) and small end hole (3) of the connecting rod (1) as positioning references, after positioning and fixing the connecting rod (1), precision milling of the upper end face of the connecting rod (1) and machining of multiple process positioning holes (4) distributed on the rod body (1-1) and rod cap (1-2) as reference holes on the upper end face of the connecting rod (1); 3) Machining process holes: After positioning and fixing the connecting rod (1) using a connecting rod fixture that is adapted to connect the lower end face of the connecting rod (1) and the two process positioning holes (4) located on the rod body (1-1), a shoulder surface (6) and a process hole (5) are machined on the large end and small end face of the connecting rod (1) respectively. After machining, the connecting rod fixture is removed. 4) Machining the arc surfaces: After fixing the connecting rod (1) with the small end end and the shoulder surface (6) of the large end end as the positioning reference, machine the two arc surfaces of the connecting rod (1); 5) Cutting: Cut the connecting rod (1) along the cleaving line to form the rod body (1-1) and the rod cap (1-2); 6) Drilling deep holes: After fixing the rod body (1-1) with a connecting rod fixture that is compatible with the process positioning holes (4) at both ends of the rod body (1-1), drill deep holes (7) on the rod body (1-1) along its mating surface. 7) Semi-finish boring of the shaft hole: Semi-finish boring of the shaft hole on the shaft (1-1); 8) Milling the rod body mating surface: After milling the mating surface of the rod body (1-1) according to the drawing requirements, machine bolt holes on the mating surface of the rod body (1-1), and then remove the connecting rod fixture; 9) Semi-finish boring of the rod cap hole: After the rod cap (1-2) is positioned and fixed by the rod cap clamp that is adapted to the lower end face of the rod cap (1-2) and the two process positioning holes (4) on the rod cap (1-2), the rod cap hole is semi-finish bored. 10) Milling the mating surface of the rod cap: After milling the mating surface of the rod cap (1-2) according to the drawing requirements, machine the screw holes on the mating surface of the rod cap (1-2) that correspond to the bolt hole positions on the mating surface of the rod body (1-1); 11) Milling the shoulder surface of the rod cap: After milling the shoulder surface (6) on the end face of the rod cap (1-2), remove the rod cap fixture; 12) Assembly: Align the mating surfaces of the rod cap (1-2) and the rod body (1-1), and fix the rod cap (1-2) and the rod body (1-1) into one piece by the bolt holes on the mating surface of the rod body (1-1) and the screw holes on the rod cap (1-2) and the nuts that are adapted to the bolt holes. 13) Precision boring: After positioning and fixing the assembled connecting rod (1) with the connecting rod fixture that is compatible with the process positioning holes (4) at both ends of the rod body (1-1), the large end hole (2) and small end hole (3) on the connecting rod (1) are precision bored.

2. The linkage machining process method with unified reference as described in claim 1, characterized in that: The connecting rod clamp includes a base body (8). The upper end of the base body (8) is fixed with three support pins (9) arranged in a triangular pattern at the same height. The three support pins (9) are respectively in contact with the middle of the small end of the connecting rod (1) and the lower end of the large end hole (2) on both sides. The base body (8) is fixed with cylindrical pins (10) and rhomboid pins (11) that are adapted to and connected to the two process positioning holes (4) on the rod body (1-1). The connecting rod (1) is pressed and fixed by multiple sets of parallel pressure plates (12) fixed to the upper end of the base body (8).

3. The linkage machining process method with unified reference as described in claim 2, characterized in that: The parallel pressure plate (12) is provided in three sets and is distributed on both sides of the small end of the connecting rod (1) and the large end of the connecting rod (1).

4. The linkage machining process method with unified reference as described in claim 3, characterized in that: The base body (8) has a T-shaped structure with the width at the right end being greater than that at the left end, and the larger end of the rod (1-1) is located at the right end of the base body (8).

5. The linkage machining process method with unified reference as described in claim 1, characterized in that: The rod cover clamp includes a base body two (13). The upper end face of the base body two (13) has three support pins two (14) distributed in a triangular shape at the same height, which are used to contact the lower end face of the rod cover (1-2) and support the rod cover (1-2). The upper end face of the base body two (13) is fixed with cylindrical pin two (15) and rhomboid pin two (16) respectively adapted to the two process positioning holes (4) on the rod cover (1-2). The rod cover (1-2) is pressed and fixed to the base body two (13) by a pressure plate (17) located at half of the large end hole (2) on the rod cover (1-2) and fixed to the base body two (13) by a long bolt.

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