Large connecting rod forge piece rough machining method

Abstract

The invention discloses a large connecting rod forge piece rough machining method which comprises the steps that smooth grooves are formed in the thick end face and / or the thin end face of a connecting rod blank piece through oxygen cutting through a connecting rod punch, local heating and local forging are conducted on the defect portion of the connecting rod blank piece, and metal moves in the direction with the minimum resistance through extrusion; therefore, the defect part of the thick-end conical surface and / or the thin-end outer circular surface can be filled, and the problem that the thick end and the thin end are partially lack of meat is solved. By means of local extrusion deformation, particles with the diameter exceeding the standard are crushed, or holes with the diameter exceeding the standard are compacted, and therefore it is guaranteed that the built-in quality of products is stable. The method is easy to operate, the needed forming force is small, the connecting rod punch is easy to manufacture, the manufacturing cost is low, and scrapped products can be saved in the production process; the method is suitable for solving the technical problem of forging defects in the rough machining process of the marine large diesel engine connecting rod.

Description

Technical Field

[0001] This invention belongs to the field of forging technology, and specifically relates to a rough machining method for large connecting rod forgings. Background Technology

[0002] With the rapid development of my country's shipbuilding industry, the demand for shipbuilding is huge, especially as my country maintains a leading global share in shipbuilding. Diesel engine moving parts, as the starting system of the hull, are core components of the hull, and connecting rods are one of the five major moving parts of a diesel engine. As the tonnage of ships manufactured in China increases, the requirements for diesel engine moving parts are also becoming more stringent. From the small and medium-sized engines like the S50MEC and S60MEC of previous years, the moving parts for large engines like the G80 MEC, X92DF, and G95 MEC currently supplied to the market have evolved. Correspondingly, connecting rods have also evolved from small and medium-sized engines to ultra-large engines. The forging process of connecting rods also varies depending on their volume and weight. Currently, the main forging method used in China is free forging, which involves heating the steel ingot billet as a whole and forming it through secondary upsetting and drawing. As the tonnage of connecting rods becomes heavier and the forging cross-section becomes larger, during the conventional forging process, uneven heating of the forging workpiece, improper use of forging tooling, changes in the operator's skill level, or inadequate process execution often result in insufficient spherical dimensions at both ends of the connecting rod (thick end conical surface or thin end outer circle surface missing material), leading to scrap due to insufficient dimensions during subsequent machining. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned technical problems and provide a rough machining method for large connecting rod forgings that is simple to operate, has low manufacturing cost, can salvage scrapped products during the production process, and ensures stable internal quality of the products.

[0004] To achieve the above objectives, the present invention provides a rough machining method for large connecting rod forgings, the specific rough machining process of which is as follows: 1) Machining the thick end outer cylindrical surface, thick end conical surface, thin end outer cylindrical surface, thin end conical surface, and rod portion of the connecting rod blank to the rough machining dimensions of the product; if a notch appears on the thick end conical surface and / or the thin end outer cylindrical surface during machining, stop machining and proceed to step 3); if no defects appear when the connecting rod blank is machined to the rough machining dimensions of the product, proceed to step 2); 2) Machin the thick end of the connecting rod blank into a thick hemisphere, the diameter of which is consistent with the rough machining dimension of the product; machine the thin end of the connecting rod blank into a thin hemisphere, the diameter of which is consistent with the rough machining dimension of the product; finally, mill the end faces of the thick and thin ends to the rough machining dimension of the product. 3) Repair the notch on the thick-end conical surface and / or the thin-end outer circular surface; 4) Continue machining the thick end outer cylindrical surface, thick end conical surface, thin end outer cylindrical surface, thin end conical surface, and rod portion of the connecting rod blank after repair in step 3) to the rough machining dimensions of the product; then machine the thick end 1.1 of the connecting rod blank into a thick end hemisphere, the diameter of which is consistent with the rough machining dimensions of the product; machine the thin end 1.7 of the connecting rod blank into a thin end hemisphere, the diameter of which is consistent with the rough machining dimensions of the product; finally, mill the end faces of the thick and thin ends to the rough machining dimensions of the product.

[0005] Further, the specific process of step 3) is as follows: If a notch appears on the thick end conical surface: use an oxy-acetylene torch to cut a thick end arc-shaped groove on the end face of the thick end of the connecting rod blank. Then, put the thick end part, the thick end conical surface part, and part of the rod part of the connecting rod blank into the heating furnace for local heating. Then, stand the connecting rod blank upright on the press platform with the thick end facing upward. Assemble the connecting block of the connecting rod punch with the press beam. Move the press beam to place the protruding punch at the thick end arc groove. Press down on the connecting rod punch to move the connecting rod punch downward until the size of the thick end conical surface meets the rough machining process requirements.

[0006] Furthermore, the arc-shaped surface of the thick-end arc-shaped groove matches the arc-shaped surface of the protruding punch of the connecting rod punch.

[0007] Furthermore, the thick end portion, the thick end conical portion, and a portion of the rod portion of the connecting rod blank are kept at 1250±20℃ for 3-5 hours.

[0008] Furthermore, the protruding punch is placed in the thick-end arc groove, and the connecting rod punch is pressed down, causing the connecting rod punch to move downward a distance of 450-500mm.

[0009] Furthermore, the other part of the rod not inserted into the heating furnace, the thin-end conical part, and the thin-end part are all covered with insulating cotton to provide thermal insulation.

[0010] Furthermore, a notch appears on the outer circular surface of the thin end: an arc-shaped groove is cut into the end face of the thin end of the connecting rod blank using an oxy-acetylene torch. Then, the thin end portion, the thin end conical portion, and a part of the rod portion of the connecting rod blank are placed in a heating furnace for local heating. The connecting rod blank is then erected on the press platform with the thin end facing upwards. The connecting block of the connecting rod punch is assembled with the press beam. The protruding punch is placed at the arc-shaped groove of the thin end by moving the press beam. The connecting rod punch is pressed down until the dimensions of the thin end conical surface meet the requirements of the rough machining process.

[0011] Furthermore, the arc-shaped surface of the thin-end arc-shaped groove matches the arc-shaped surface of the protruding punch of the connecting rod punch.

[0012] Furthermore, the thin end portion, the thin end conical portion, and a part of the rod portion of the connecting rod blank are removed from the furnace after being kept at 1250±20℃ for 3-5 hours, and the connecting rod punch moves downward by a distance of 450-500mm.

[0013] Furthermore, the other part of the rod not inserted into the heating furnace, the thin-end conical part, and the thin-end part are all covered with insulating cotton to provide thermal insulation.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention designs a special connecting rod punch, cuts smooth grooves on the thick and / or thin end faces of the connecting rod blank, and locally heats and forges the defective parts of the connecting rod blank. Through extrusion, the metal moves in the direction of least resistance, thereby filling the defective parts of the thick end conical surface and / or the thin end outer circular surface, thus solving the problem of local missing material at the thick and thin ends. Through local extrusion deformation, particles exceeding the diameter limit are crushed, or holes exceeding the diameter limit are compacted, thereby ensuring stable internal quality of the product. This invention is simple to operate, requires low forming force, the tooling (i.e., the connecting rod punch) is easy to manufacture, has low manufacturing cost, and can salvage scrapped products during production. The method of this invention is applicable to solving the technical problem of forging defects in the rough machining process of connecting rods for large marine diesel engines. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a connecting rod blank. Figure 2 Schematic diagram of the notch on the thick end of the connecting rod blank; Figure 3 A schematic diagram of the thin-end conical notch of the connecting rod blank; Figure 4 This is a schematic diagram of the thick-end conical surface repair process; Figure 5 This is a schematic diagram of the thin-end conical surface repair process. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] When rough machining large connecting rod forgings, first turn the outer cylindrical surface of the thick end, the outer cylindrical surface of the thick end, the outer cylindrical surface of the thin end, the thin end, and the rod portion of the connecting rod blank to the rough machining dimensions of the product; then machine the thick end of the connecting rod blank into a thick end hemisphere, with the diameter of the thick end hemisphere matching the rough machining dimensions of the product; similarly, machine the thin end of the connecting rod blank into a thin end hemisphere, with the diameter of the thin end hemisphere matching the rough machining dimensions of the product; finally, mill the end faces of the thick and thin ends to the rough machining dimensions of the product.

[0018] However, during actual forging, uneven heating of the forging, improper use of forging fixtures, changes in the operator's skill level, or inadequate execution of the process often result in missing material on the thick end conical surface or the thin end outer cylindrical surface of the connecting rod, leading to scrap due to insufficient dimensions during subsequent machining.

[0019] To overcome the above-mentioned technical defects, the rough machining process of the large connecting rod forging method of the present invention is as follows: 1) such as Figure 1 Machining the thick end outer cylindrical surface 1.2, the thick end conical surface 1.3, the thin end outer cylindrical surface 1.6, the thin end conical surface 1.5, and the rod portion 1.4 of the connecting rod blank 1, respectively, to the rough machining dimensions of the product; if a notch 2 appears on the thick end conical surface and / or the thin end outer cylindrical surface during machining (e.g. Figure 2 , 3 If the connecting rod blank is machined to the rough-machined dimensions of the product and no defects are found, then proceed to step 2). 2) Machin the thick end 1.1 of the connecting rod blank into a thick end hemisphere, the diameter of which is consistent with the rough machining dimension of the product; similarly, machine the thin end 1.7 of the connecting rod blank into a thin end hemisphere, the diameter of which is consistent with the rough machining dimension of the product; finally, mill the end faces of the thick and thin ends to the rough machining dimension of the product. 3) If a notch 2 appears on the thick-end conical surface: such as Figure 4 As shown, an arc-shaped groove 3 is cut into the thick end face of the connecting rod blank using an oxy-acetylene torch. The arc-shaped surface of this groove 3 matches the arc-shaped surface of the protruding punch 4.1 of the connecting rod punch 4. Then, the thick end portion, the thick end conical portion, and a part of the rod portion of the connecting rod blank are placed in a heating furnace for localized heating. After holding at 1250±20℃ for 3-5 hours, the blank is removed from the furnace and placed upright on the press platform with the thick end facing upwards. The connecting block 4.2 of the connecting rod punch 4 is then assembled with the press crossbeam. The protruding punch is placed in the thick-end arc groove by moving the press beam. The connecting rod punch is pressed down, causing it to move downwards by 450-500mm. During the downward movement of the connecting rod punch, the other part of the connecting rod blank, the thin-end conical part, and the thin-end part will not undergo plastic deformation because they are not heated. However, the thick end is squeezed and undergoes local plastic deformation. The metal moves to the area with less resistance and can then flow to the notch position of the thick-end conical surface, so that the dimensions of the thick-end conical surface meet the requirements of the rough machining process.

[0020] In this embodiment, the other part of the rod not installed in the heating furnace, the thin-end conical part, and the thin-end part are all covered with insulation cotton to provide thermal insulation; the length of the thick-end arc-shaped groove is 500-600mm and the depth is 70-80mm.

[0021] And / or a notch appears on the outer surface of the thin end: such as Figure 5As shown, an arc-shaped groove 5 is cut into the thin end face of the connecting rod blank using an oxy-acetylene torch. The arc surface of this arc-shaped groove 5 matches the arc surface of the protruding punch 4.1 of the connecting rod punch 4. Then, the thin end portion, the thin end conical portion, and a part of the rod portion of the connecting rod blank are placed in a heating furnace for local heating. After holding at 1250±20℃ for 3-5 hours, the blank is removed from the furnace and placed upright on the press platform with the thin end facing upwards. The connecting block 4.2 of the connecting rod punch 4 is then assembled with the press crossbeam. The movement of the press beam places the protruding punch at the thin-end arc groove, presses down the connecting rod punch, and moves the connecting rod punch downwards by 450-500mm. During the downward movement of the connecting rod punch, the other part of the connecting rod blank, the thick-end conical part, and the thick-end part will not undergo plastic deformation because they are not heated, while the thin end is squeezed and undergoes local plastic deformation. The metal moves to the place with less resistance and can then flow to the notch position on the outer circle surface of the thin end, so that the size of the thin-end conical surface meets the requirements of the rough machining process.

[0022] In this embodiment, the other part of the rod not installed in the heating furnace, the thin-end conical part, and the thin-end part are all covered with insulation cotton to provide thermal insulation; the length of the arc-shaped groove at the thin end is 500-600mm and the depth is 70-80mm.

[0023] 4) Continue machining the thick end outer cylindrical surface, thick end conical surface, thin end outer cylindrical surface, thin end conical surface, and rod portion of the connecting rod blank after repair in step 3) to the rough machining dimensions of the product; then machine the thick end 1.1 of the connecting rod blank into a thick end hemisphere, the diameter of which is consistent with the rough machining dimensions of the product; similarly, machine the thin end 1.7 of the connecting rod blank into a thin end hemisphere, the diameter of which is consistent with the rough machining dimensions of the product; finally, mill the end faces of the thick and thin ends to the rough machining dimensions of the product.

[0024] The connecting rod punch 4 includes a connecting block 4.2 and a protruding punch 4.1. The connecting block is assembled with the press beam and is locked in the groove of the press beam, serving a fixing and positioning function. The protruding punch is a spherical body that contacts the arc-shaped groove cut by oxygen cutting. The arc-shaped groove and the arc-shaped surface of the protruding punch contact each other, which can significantly reduce the pressure required for forming. This invention uses the connecting rod punch to perform local extrusion and deformation, breaking down the original coarse and uneven particles inside the metal. Through recrystallization, it becomes a finer, more uniform equiaxed crystalline structure. The bubbles and loose structures on the surface that have not undergone oxidation are also compacted and welded through forging and extrusion deformation, thereby ensuring the internal quality stability of the product.

[0025] This invention solves the problem of localized material shortages at the thick and / or thin ends of a connecting rod blank by designing a specialized connecting rod punch and performing localized heating and forging on defective areas. Through extrusion, the metal moves in the direction of least resistance, filling defects on the thick-end conical surface and / or thin-end outer surface, thus addressing the issue of material shortages at the thick and thin ends. Localized extrusion deformation crushes oversized particles or compacts oversized holes, ensuring stable internal quality of the product. This invention is simple to operate, requires low forming force, and the tooling (connecting rod punch) is easy to manufacture, resulting in low production costs. It can also salvage scrapped products during production. This method is applicable to solving forging defects in the rough machining of connecting rods for large marine diesel engines.

Claims

1. A method for rough machining large connecting rod forgings, characterized in that: The specific roughing process is as follows: 1) Machining the thick end outer cylindrical surface, thick end conical surface, thin end outer cylindrical surface, thin end conical surface, and rod portion of the connecting rod blank to the rough machining dimensions of the product; if a notch appears on the thick end conical surface and / or the thin end outer cylindrical surface during machining, stop machining and proceed to step 3); if no defects appear when the connecting rod blank is machined to the rough machining dimensions of the product, proceed to step 2); 2) The thick end of the connecting rod blank is machined into a thick end hemisphere, and the diameter of the thick end hemisphere is consistent with the rough machining dimension of the product; The thin end of the connecting rod blank is machined into a thin-end hemisphere, and the diameter of the thin-end hemisphere is consistent with the rough machining dimension of the product; finally, the end faces of the thick end and the thin end are milled to the rough machining dimension of the product. 3) Repair the notch on the thick-end conical surface and / or the thin-end outer circular surface; 4) Continue machining the thick end outer cylindrical surface, thick end conical surface, thin end outer cylindrical surface, thin end conical surface, and rod portion of the connecting rod blank after repair in step 3) to the rough machining dimensions of the product; then machine the thick end 1.1 of the connecting rod blank into a thick end hemisphere, the diameter of which is consistent with the rough machining dimensions of the product; machine the thin end 1.7 of the connecting rod blank into a thin end hemisphere, the diameter of which is consistent with the rough machining dimensions of the product; finally, mill the end faces of the thick and thin ends to the rough machining dimensions of the product.

2. The rough machining method for large connecting rod forgings according to claim 1, characterized in that: The specific process of step 3) is as follows: If a notch appears on the thick end conical surface: use an oxy-acetylene torch to cut a thick end arc-shaped groove on the end face of the thick end of the connecting rod blank. Then, put the thick end part, the thick end conical surface part, and part of the rod part of the connecting rod blank into the heating furnace for local heating. Then, stand the connecting rod blank upright on the press platform with the thick end facing upward. Assemble the connecting block of the connecting rod punch with the press beam. Move the press beam to place the protruding punch at the thick end arc groove. Press down on the connecting rod punch to move the connecting rod punch downward until the size of the thick end conical surface meets the rough machining process requirements.

3. The rough machining method for large connecting rod forgings according to claim 2, characterized in that: The arc-shaped surface of the thick-end arc-shaped groove matches the arc-shaped surface of the protruding punch of the connecting rod punch.

4. The rough machining method for large connecting rod forgings according to claim 2, characterized in that: The thick end portion, the thick end conical portion, and a part of the rod portion of the connecting rod blank are kept at 1250±20℃ for 3-5 hours.

5. The rough machining method for large connecting rod forgings according to claim 2, characterized in that: The protruding punch is placed in the thick-end arc groove, and the connecting rod punch is pressed down. The connecting rod punch moves downward a distance of 450-500mm.

6. The rough machining method for large connecting rod forgings according to claim 2, characterized in that: The other part of the rod not inserted into the heating furnace, the thin-end conical part, and the thin-end part are all covered with insulation cotton to provide thermal insulation.

7. The rough machining method for large connecting rod forgings according to claim 1, characterized in that: The thin end outer circular surface has a notch: an arc-shaped groove is cut into the end face of the thin end of the connecting rod blank using an oxy-acetylene torch. Then, the thin end part, the thin end conical part, and a part of the rod part of the connecting rod blank are placed in a heating furnace for local heating. The connecting rod blank is then erected on the press platform with the thin end facing upwards. The connecting block of the connecting rod punch is assembled with the press beam. The protruding punch is placed at the arc-shaped groove of the thin end by moving the press beam. The connecting rod punch is pressed down until the size of the thin end conical surface meets the rough machining process requirements.

8. The rough machining method for large connecting rod forgings according to claim 7, characterized in that: The arc-shaped surface of the thin-end arc-shaped groove matches the arc-shaped surface of the protruding punch of the connecting rod punch.

9. The rough machining method for large connecting rod forgings according to claim 7, characterized in that: The thin end portion, the thin end conical portion, and a part of the rod portion of the connecting rod blank are removed from the furnace after being kept at 1250±20℃ for 3-5 hours, and the connecting rod punch moves downward by a distance of 450-500mm.

10. The rough machining method for large connecting rod forgings according to claim 7, characterized in that: The other part of the rod not inserted into the heating furnace, the thin-end conical part, and the thin-end part are all covered with insulation cotton to provide thermal insulation.

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