High-horsepower connecting rod cracking process

Abstract

The invention discloses a high-horsepower connecting rod cracking process. The process comprises the following steps: preparing a connecting rod blank; pretreating a connecting rod blank; prefabricating cracks; cracking the connecting rod; and post-processing the connecting rod. The high-horsepower connecting rod cracking process control method has the beneficial effects that the high-horsepower connecting rod cracking process is accurately controlled by optimizing the material formula and the precrack precision and integrating a visual detection system, and compared with a traditional process, the high-horsepower connecting rod cracking process control method has the following advantages that the roughness of a fracture surface is reduced by 30%-50%, and the subsequent machining amount is reduced by 40%; the consistency of crack propagation paths reaches 95% or above, and the material utilization rate is increased by 15%-20%; the cracking efficiency is improved by 25%, process parameters can be monitored in real time, and the rejection rate is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engine high-power connecting rod, and particularly relates to a high-power connecting rod breaking process. BACKGROUND

[0002] The connecting rod is a key transmission component of the engine, and the strength and fracture surface quality of the connecting rod directly affect the performance and service life of the engine. The traditional connecting rod processing technology (such as milling and sawing) has problems such as rough fracture surface, material waste, low processing efficiency, and difficulty in ensuring the consistency and mechanical properties of the fracture surface. The breaking process, as an efficient breaking processing technology, can obtain a more regular fracture surface and reduce the subsequent processing amount by preforming a crack and applying a controllable load to make the connecting rod split. However, the existing breaking process still has the following deficiencies in the application of high-power connecting rods (under high load conditions):

[0003] 1. The traditional material formula cannot balance the strength and fracture toughness, resulting in uncontrolled crack propagation;

[0004] 2. The pre-crack precision is insufficient, the crack propagation path is random, and the fracture surface quality is unstable;

[0005] 3. There is a lack of real-time monitoring means, and the process parameters cannot be dynamically adjusted to adapt to material differences and load fluctuations.

[0006] Therefore, it is necessary to propose a high-power connecting rod breaking process for the above technical solutions. SUMMARY

[0007] In order to make up for the deficiencies of the prior art, the present application proposes a high-power connecting rod breaking process, which realizes accurate control of crack propagation during the breaking process of the connecting rod through material formula optimization, pre-crack technology and visual detection system, and improves the fracture surface quality and production efficiency.

[0008] The technical scheme adopted by the present application to solve its technical problems is:

[0009] A high-power connecting rod breaking process, the process steps of which are:

[0010] S1, connecting rod blank preparation;

[0011] S2, connecting rod blank pretreatment;

[0012] S3, pre-crack;

[0013] S4, connecting rod breaking;

[0014] S5, connecting rod post-processing.

[0015] The connecting rod blank preparation process step in step S1 is:

[0016] (1)Batching: take the following raw materials by weight parts, among them, cast steel powder 120-220 parts, manganese powder 8-12 parts, copper powder 4-8 parts, chromium powder 2-4 parts, cobalt powder 1-3 parts, molybdenum powder 2-3 parts, silicon carbide powder 2-3 parts, aluminum nitride powder 2-3 parts, barium titanate powder 1-3 parts, zinc stearate 0.2-0.3 parts, calcium fluoride 0.1-0.2 parts, methyl methacrylate 0.1-0.2 parts;

[0017] (2) Preparation of auxiliary: mix zinc stearate and calcium fluoride of step (1), add water with equal mass of the mixture, stir at 600 rpm for 12 minutes, add methyl methacrylate, then slowly raise the temperature to 80℃, constant temperature stirring for 30 minutes, stirring speed is 1000 rpm, finally dry, crush into powder above 800 mesh, get;

[0018] (3) Thermal reaction: add cast steel powder, manganese powder, copper powder, chromium powder, cobalt powder, molybdenum powder, silicon carbide powder, aluminum nitride powder and barium titanate powder in step (1) to the reactor, stir evenly, then add the auxiliary prepared in step (2), heat to 300-350℃, stir while heating, stirring speed is 1000 rpm, after 10 minutes, stop stirring to get compound A;

[0019] (4) Secondary mixing: when the temperature of compound A decreases to 30℃, then add silica gel powder in step 1) to the reactor, stir evenly to get compound B;

[0020] (5) Sintering: take out compound B, press into block under 8-10 Mpa pressure, then sinter at 800-900℃ for 3-5 hours under nitrogen protection atmosphere, then cool to room temperature, get.

[0021] The mass fraction of each component in the cast steel powder is as follows: C: 0.9-1.2%, Mn: 0.8-1.1%, Si: 0.4-0.7%, and the balance is Fe.

[0022] The particle size of cast steel powder, manganese powder, copper powder, chromium powder, cobalt powder, molybdenum powder, silicon carbide powder, aluminum nitride powder, barium titanate powder and silica gel powder is controlled above 650 mesh.

[0023] Among them, the pretreatment of connecting rod blank includes heat treatment: heat treatment of the blank, annealing, normalizing or quenching and tempering treatment to improve the mechanical properties of the material, improve the toughness and fracture performance of the material, and prepare for the fracture process. Surface treatment: polishing, polishing and other treatments are carried out on the inner surface of the connecting rod big head hole to remove the surface scale, burrs and defects, ensure the quality of the prefabricated crack and the consistency of crack propagation.

[0024] Wherein the prefabricated crack is prefabricated V-shaped crack groove by double laser head synchronous cutting technology, and Nb-Ti composite microalloyed non-quenched and tempered steel is used and the controlled cooling process is optimized.

[0025] Wherein the crack groove depth is 0.4-0.57mm, the opening angle is 15°-20°, and the curvature radius is 0.1-0.2mm; the carbon equivalent Ceq of the non-quenched and tempered steel is 0.85-1.03, the cooling rate is 2.2-3.5℃ / s, and the final cooling temperature is 600-650℃.

[0026] Wherein the connecting rod is installed on the breaking equipment by connecting rod breaking, and the crack is expanded along the predetermined direction by applying tensile load or bending load, and finally the big end of the connecting rod is split into connecting rod body and connecting rod cover two parts. During the breaking process, the size of the load, the loading speed and the loading direction need to be controlled to ensure the stability of the crack propagation and the quality of the fracture surface. For the tensile breaking process, the loading speed is generally 1-5mm / s, and the load size is determined according to the material strength of the connecting rod and the size of the prefabricated crack, and is usually 80%-90% of the yield strength of the material; the breaking force is loaded in stages, the initial rate is 5-10kN / s, the subsequent rate is 1-2kN / s, and the target force is 150-200kN; the breaking force is applied in stages and integrated with the visual detection system.

[0027] The connecting rod post-processing deburring: deburring the fracture surface of the connecting rod body and the connecting rod cover after breaking, to remove the sharp edges and burrs on the fracture surface, to avoid scratching other parts during assembly;

[0028] Finish machining: finish machining the big end hole, small end hole, rod body and other parts of the connecting rod body and connecting rod cover,

[0029] Such as boring, grinding, honing, etc., to achieve the size accuracy and surface roughness required by the design;

[0030] Surface treatment: according to the use requirements, the connecting rod is surface treated, such as electroplating, spraying, carburizing, etc., to improve the wear resistance, corrosion resistance and oxidation resistance of the connecting rod.

[0031] Wherein the visual detection system analyzes the crack propagation path by AI algorithm and dynamically adjusts the process parameters; the algorithm steps are:

[0032] S11, image preprocessing and crack segmentation, wherein image enhancement and denoising are adopted, and Gaussian filter denoising is adopted, and the Gaussian filter formula is:

[0033]

[0034] Wherein σ is the standard deviation, and (x0, y0) is the kernel center;

[0035] The crack edge detection and segmentation adopts Canny edge detection,

[0036]

[0037] where I(x, y) is the image gray value; G x ,G y are the gradients in x and y directions;

[0038] S12, crack feature extraction and characterization, key point detection is performed using skeletonization algorithm, skeletonization is based on distance transformation:

[0039]

[0040] where C is the crack region, is the boundary, d(·) is the distance function; crack feature parameter extraction, contour tracking is used, the direction vector of the contour point

[0041] θ i = arctan 2(y i+1 -y i , x i+1 -x i ), where (x i , y i ) is the point on the contour;

[0042] S13, crack propagation path tracking algorithm, intra-frame path connection (static analysis), path cost function is used:

[0043]

[0044] where p is the path point, w(p i , p i+1 ) is the distance cost of adjacent points, c(p i ) is the reliability of the point, λ is the weight coefficient; cross-frame time sequence tracking is performed using the optical flow method, where the optical flow constraint equation I x u+I y v+I t = 0

[0045] where I x , I y , I t are the gradients of the image in x, y directions and time t, (u, v) is the pixel motion vector;

[0046] S14, optimization and model fitting of the propagation path, the path is smoothed and de-noised using the Bezier curve fitting, where the cubic Bezier curve

[0047] B(t) = (1-t) 3 P0+3(1-t)2 tP1+3(1-t)t 2 P2+t 3 P3, t [0, 1]

[0048] Wherein P0, P1, P2, P3 are control points;

[0049] Expansion direction and rate modeling, expansion rate calculation Wherein L(t) is the crack length at t time, and At is the time interval.

[0050] The beneficial effects of the present application: the present application realizes the precise control of the large horsepower connecting rod expansion and breaking process by optimizing the material formula, the precision of the prefabricated crack and the integrated visual detection system, compared with the traditional process, has the following advantages: the roughness of the fracture surface is reduced by 30%-50%, the subsequent processing amount is reduced by 40%; the crack expansion path consistency is more than 95%, the material utilization rate is increased by 15%-20%; the expansion and breaking efficiency is increased by 25%, and the process parameters can be monitored in real time, and the waste rate is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0052] Fig. 1 The process flowchart of the present application;

[0053] Fig. 2 The visual detection algorithm flowchart of the present application. DETAILED DESCRIPTION

[0054] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0055] The embodiments of the present application will be described in detail below in combination with the drawings, but the present application can be implemented in many different ways limited and covered by the claims.

[0056] The following will be described in combination with the drawings Figs. 1-2 The present application will be further described in detail,

[0057] A large horsepower connecting rod expansion and breaking process, the process steps are:

[0058] S1, connecting rod blank preparation;

[0059] S2, connecting rod blank pretreatment;

[0060] S3, preparing a pre-crack;

[0061] S4, breaking the connecting rod;

[0062] S5, post-processing of the connecting rod.

[0063] The step S1 of the connecting rod blank preparation process is as follows: (1) batching: take the following raw materials according to weight parts, among which, cast steel powder 120-220 parts, manganese powder 8-12 parts, copper powder 4-8 parts, chromium powder 2-4 parts, cobalt powder 1-3 parts, molybdenum powder 2-3 parts, silicon carbide powder 2-3 parts, aluminum nitride powder 2-3 parts, barium titanate powder 1-3 parts, zinc stearate 0.2-0.3 parts, calcium fluoride 0.1-0.2 parts, methyl methacrylate 0.1-0.2 parts; (2) preparation of additives: mix the zinc stearate and calcium fluoride of step (1), add water with the same mass as the mixture, stir at 600 rpm for 12 minutes, add methyl methacrylate, then slowly raise the temperature to 80℃, constant temperature stirring for 30 minutes, stirring speed is 1000 rpm, finally dry and crush into powder above 800 mesh; (3) thermal reaction: add the cast steel powder, manganese powder, copper powder, chromium powder, cobalt powder, molybdenum powder, silicon carbide powder, aluminum nitride powder and barium titanate powder in step (1) into the reactor, stir evenly, then add the additives prepared in step (2), heat to 300-350℃, stir while heating, stirring speed is 1000 rpm, after 10 minutes, stop stirring to get compound A; (4) secondary mixing: when the temperature of compound A decreases to 30℃, then add the silica gel powder in step 1) into the reactor, stir evenly to get compound B; (5) sintering: take out the compound B, press into block under 8-10 Mpa pressure, then sinter at 800-900℃ for 3-5 hours under nitrogen atmosphere, then cool to room temperature to get the product.

[0064] The mass fraction of each component in the cast steel powder is as follows: C: 0.9-1.2%, Mn: 0.8-1.1%, Si: 0.4-0.7%, and the balance is Fe.

[0065] The particle size of the cast steel powder, manganese powder, copper powder, chromium powder, cobalt powder, molybdenum powder, silicon carbide powder, aluminum nitride powder, barium titanate powder and silica gel powder is controlled above 650 mesh.

[0066] The connecting rod blank pretreatment includes heat treatment: heat treatment of the blank, annealing, normalizing or quenching and tempering treatment to improve the mechanical properties of the material, increase the toughness and fracture performance of the material, and prepare for the breaking process. Surface treatment: polishing, polishing and other treatments are carried out on the inner surface of the connecting rod big head hole to remove the surface scale, burrs and defects, and ensure the quality of the pre-crack and the consistency of crack propagation.

[0067] Wherein the prefabricated crack is prefabricated V-shaped crack groove by double laser head synchronous cutting technology, and Nb-Ti composite microalloyed non-quenched and tempered steel is used and the controlled cooling process is optimized.

[0068] Wherein the crack groove depth is 0.4-0.57mm, the opening angle is 15°-20°, and the curvature radius is 0.1-0.2mm; the carbon equivalent Ceq of the non-quenched and tempered steel is 0.85-1.03, the cooling rate is 2.2-3.5℃ / s, and the final cooling temperature is 600-650℃.

[0069] Wherein the connecting rod is installed on the breaking equipment by connecting rod breaking, and the crack is expanded along the predetermined direction by applying tensile load or bending load, and finally the big end of the connecting rod is split into connecting rod body and connecting rod cover two parts. During the breaking process, the size of the load, the loading speed and the loading direction need to be controlled to ensure the stability of the crack propagation and the quality of the fracture surface. For the tensile breaking process, the loading speed is generally 1-5mm / s, and the load size is determined according to the material strength of the connecting rod and the size of the prefabricated crack, and is usually 80%-90% of the yield strength of the material; the breaking force is loaded in stages, the initial rate is 5-10kN / s, the subsequent rate is 1-2kN / s, and the target force is 150-200kN; the breaking force is applied in stages and integrated with the visual detection system.

[0070] The connecting rod post-processing deburring: deburring the fracture surface of the connecting rod body and the connecting rod cover after breaking, to remove the sharp edges and burrs on the fracture surface, to avoid scratching other parts during assembly;

[0071] Finish machining: finish machining the big end hole, small end hole, rod body and other parts of the connecting rod body and connecting rod cover,

[0072] Such as boring, grinding, honing, etc., to achieve the size accuracy and surface roughness required by the design;

[0073] Surface treatment: according to the use requirements, the connecting rod is surface treated, such as electroplating, spraying, carburizing, etc., to improve the wear resistance, corrosion resistance and oxidation resistance of the connecting rod.

[0074] Wherein the visual detection system analyzes the crack propagation path by AI algorithm and dynamically adjusts the process parameters; the algorithm steps are:

[0075] S11, image preprocessing and crack segmentation, wherein image enhancement and denoising are adopted, and Gaussian filter denoising is adopted, and the Gaussian filter formula is:

[0076]

[0077] Wherein σ is the standard deviation, and (x0, y0) is the kernel center;

[0078] The crack edge detection and segmentation adopts Canny edge detection,

[0079]

[0080] Where I(x, y) is the image grayscale value; G x G y The gradients are in the x and y directions;

[0081] S12. Crack feature extraction and characterization: Key point detection is performed using the skeletonization algorithm, which is based on distance transformation.

[0082]

[0083] Where C represents the crack region. Let d(·) be the boundary, and d(·) be the distance function;

[0084] Crack feature parameters are extracted using contour tracing, specifically the direction vectors of the contour points.

[0085] θ i =arctan 2(y i+1 -y i x i+1 -x i ), where (x i ,y i () represents a point on the contour;

[0086] S13, Crack propagation path tracing algorithm, intra-frame path connectivity (static analysis), using the path cost function:

[0087]

[0088] in For path points, w(p) i p i+1 ) represents the distance cost between adjacent points, c(p) i ) represents the confidence level of a point, and λ is the weighting coefficient; optical flow is used for cross-frame temporal tracking, where the optical flow constraint equation I x u+I y v+I t =0

[0089] Where I x I y I t Let (u, v) be the gradient of the image in the x and y directions and at time t, and (u, v) be the pixel motion vector.

[0090] S14. Extended path optimization and model fitting: Path smoothing and artifact removal are achieved using Bézier curves, including cubic Bézier curves.

[0091] B(t)=(1-t)3 P0+3(1-t) 2 tP1+3(1-t)t 2 P2+t 3 P2,t∈[0,1]

[0092] wherein P0, P1, P2, P3 are control points;

[0093] Expansion direction and rate modeling, expansion rate calculation wherein L(t) is the crack length at time t, and Δt is the time interval.

[0094] The present application has the following advantages: the present application realizes precise control of the large-horsepower connecting rod expansion and breaking process by optimizing the material formula, pre-crack precision and integrated visual detection system, and has the following advantages compared with the traditional process: the roughness of the fracture surface is reduced by 30%-50%, and the subsequent processing amount is reduced by 40%; the crack expansion path consistency is above 95%, and the material utilization rate is increased by 15%-20%; the expansion and breaking efficiency is increased by 25%, and the process parameters can be monitored in real time, and the waste product rate is reduced.

[0095] Working principle

[0096] Example 1: Medium-load large-horsepower connecting rod expansion and breaking process

[0097] Blank preparation: ingredients (weight parts): cast steel powder 170 parts, manganese powder 10 parts, copper powder 6 parts, chromium powder 3 parts, cobalt powder 2 parts, molybdenum powder 2.5 parts, silicon carbide powder 2.5 parts, aluminum nitride powder 2.5 parts, barium titanate powder 2 parts, zinc stearate 0.25 parts, calcium fluoride 0.15 parts, methyl methacrylate 0.15 parts; cast steel powder composition: C 1.05%, Mn 0.95%, Si 0.55%, balance Fe; sintering process: 900 DEG C, nitrogen protection, sintering for 4 hours, pressing pressure 9 MPa. Pre-crack: crack groove parameters: depth 0.5 mm, opening angle 18 DEG, curvature radius 0.15 mm; material: Nb-Ti composite microalloyed non-quenched and tempered steel, Ceq 0.92, cooling rate 2.8 DEG C / s, final cooling temperature 630 DEG C.

[0098] Expansion and breaking process: tensile load: target force 180 kN, staged loading (initial rate 8 kN / s, subsequent rate 1.5 kN / s), loading speed 3 mm / s; visual detection: AI algorithm adjusts the load in real time, path cost function weight λ=0.6. Post-processing: large head hole size precision ±0.015 mm, surface roughness Ra 0.6 μm; carburizing and quenching, hardness HRC 58-62.

[0099] Example 2: High-load large-horsepower connecting rod expansion and breaking process

[0100] Blank preparation: ingredients (parts by weight): cast steel powder 220 parts, manganese powder 12 parts, copper powder 8 parts, chromium powder 4 parts, cobalt powder 3 parts, molybdenum powder 3 parts, silicon carbide powder 3 parts, aluminum nitride powder 3 parts, barium titanate powder 3 parts, zinc stearate 0.3 parts, calcium fluoride 0.2 parts, methyl methacrylate 0.2 parts;

[0101] Cast steel powder composition: C 1.2%, Mn 1.1%, Si 0.7%, balance Fe; sintering process: 850°C, nitrogen protection, sintering for 5 hours, pressing pressure 10 MPa. Pre-crack: crack groove parameters: depth 0.57 mm, opening angle 20°, curvature radius 0.2 mm; material: Nb-Ti composite microalloyed non-quenched and tempered steel, Ceq 1.03, cooling rate 3.5°C / s, final cooling temperature 600°C.

[0102] Stretching process: tensile load: target force 200 kN, staged loading (initial rate 10 kN / s, subsequent rate 2 kN / s), loading speed 5 mm / s;

[0103] Visual inspection: AI algorithm adjusts load in real time, path cost function weight λ = 0.8. Post-processing: large head hole size accuracy ± 0.01 mm, surface roughness Ra 0.4 μm; electroplated hard chromium, plating layer thickness 50 μm.

[0104] The following Table 1 is obtained from the above examples:

[0105]

[0106] According to the analysis of Table 1, it can be concluded that: Example 1 optimizes the fracture toughness while ensuring the strength through moderate alloy ratio and balanced pre-crack parameters, is suitable for medium load conditions, and the overall efficiency is significantly improved;

[0107] Example 2 meets the fracture resistance requirements under high load conditions through high alloy content and strengthened pre-crack precision, and the fracture surface quality is further improved, but the stretching efficiency is slightly reduced due to the increase in load;

[0108] Compared with the traditional process, both examples realize the comprehensive improvement of fracture surface quality, material utilization rate and production efficiency through material formula optimization, pre-crack technology and visual inspection system integration, which verifies the advancement and adaptability of the process.

[0109] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A heavy-duty connecting rod stretch process characterized by: The process steps are: S1, connecting rod blank preparation; S2, connecting rod blank pretreatment; S3, prefabricated crack; S4, connecting rod expansion; S5, connecting rod post-processing.

2. A high horsepower connecting rod stretch process as set forth in claim 1 wherein: The process steps of connecting rod blank preparation in step S1 are: (1) batching: take the following raw materials according to weight parts, among which, cast steel powder 120-220 parts, manganese powder 8-12 parts, copper powder 4-8 parts, chromium powder 2-4 parts, cobalt powder 1-3 parts, molybdenum powder 2-3 parts, silicon carbide powder 2-3 parts, aluminum nitride powder 2-3 parts, barium titanate powder 1-3 parts, zinc stearate 0.2-0.3 parts, calcium fluoride 0.1-0.2 parts, methyl methacrylate 0.1-0.2 parts; (2) agent preparation: mix the zinc stearate and calcium fluoride of step (1), add water with the same mass as the mixture, stir at a speed of 600 rpm for 12 minutes, add methyl methacrylate, then slowly raise the temperature to 80℃, stir at a speed of 1000 rpm for 30 minutes, and finally dry and crush into a powder of more than 800 mesh; (3) thermal reaction: add the cast steel powder, manganese powder, copper powder, chromium powder, cobalt powder, molybdenum powder, silicon carbide powder, aluminum nitride powder, and barium titanate powder in step (1) to the reactor, stir evenly, then add the auxiliary agent prepared in step (2), heat to 300-350℃, stir while heating, the stirring speed is 1000 rpm, after 10 minutes, stop stirring to obtain compound A; (4) secondary mixing: when the temperature of compound A decreases to 30℃, then add the silica gel powder in step (1) to the reactor, stir evenly to obtain compound B; (5) sintering: take out compound B, press into a block under a pressure of 8-10 Mpa, then sinter at 800-900℃ for 3-5 hours under a nitrogen protective atmosphere, and then cool to room temperature to obtain the product.

3. A high horsepower connecting rod stretch process as in claim 1 wherein: The mass fraction of each component in the cast steel powder is as follows: C: 0.9-1.2%, Mn: 0.8-1.1%, Si: 0.4-0.7%, and the balance is Fe.

4. A high horsepower connecting rod stretch process as in claim 1 wherein: The particle size of the cast steel powder, manganese powder, copper powder, chromium powder, cobalt powder, molybdenum powder, silicon carbide powder, aluminum nitride powder, barium titanate powder, and silica gel powder is controlled to be more than 650 mesh.

5. A high horsepower connecting rod stretch process as set forth in claim 1 wherein: The connecting rod blank pretreatment includes heat treatment: annealing, normalizing or quenching and tempering treatment of the blank; surface treatment: polishing, polishing and other treatments on the inner surface of the connecting rod big head hole, removing the surface scale, burrs and defects, ensuring the quality of the prefabricated crack and the consistency of crack propagation.

6. A high horsepower connecting rod stretch process as set forth in claim 1 wherein: The prefabricated crack adopts double laser head synchronous cutting technology to prefabricate V-shaped crack groove, uses Nb-Ti composite microalloyed non-quenched and tempered steel and optimizes the controlled cooling process.

7. A heavy-duty connecting rod stretch process as defined in claim 6 wherein: The crack groove depth is 0.4-0.57mm, the opening angle is 15°-20°, the curvature radius is 0.1-0.2mm; the carbon equivalent Ceq of the non-quenched and tempered steel is 0.85-1.03, the cooling rate is 2.2-3.5℃ / s, and the final cooling temperature is 600-650℃.

8. A high horsepower connecting rod stretch process as set forth in claim 1 wherein: The connecting rod is installed on the stretching device by the stretching load or the bending load, so that the crack is expanded along the predetermined direction, and finally the big end of the connecting rod is split into the connecting rod body and the connecting rod cover; during the stretching process, the size, the loading speed and the loading direction of the load are controlled to ensure the stability of the crack expansion and the quality of the fracture surface; for the stretching stretching process, the loading speed is generally 1-5mm / s, and the size of the load is determined according to the material strength of the connecting rod and the size of the pre-crack, and is generally 80%-90% of the yield strength of the material; the stretching force is loaded in stages, the initial rate is 5-10kN / s, the subsequent rate is 1-2kN / s, and the target force is 150-200kN; the stretching force is applied in stages and integrated with the visual detection system.

9. A high horsepower connecting rod stretch process as in claim 1 wherein: The connecting rod post-processing deburring: the fracture surface of the connecting rod body and the connecting rod cover after stretching is deburred to remove the sharp edges and burrs on the fracture surface to avoid scratching other parts during assembly; Finish machining: finish machining is performed on the big end hole, small end hole, rod body and other parts of the connecting rod body and the connecting rod cover; Surface treatment: according to the use requirements, the surface of the connecting rod is treated to improve the wear resistance, corrosion resistance and oxidation resistance of the connecting rod.

10. A high horsepower connecting rod stretch process as set forth in claim 1, characterized in that: The visual detection system analyzes the crack propagation path through an AI algorithm and dynamically adjusts the process parameters; The algorithm steps are as follows: S11, image preprocessing and crack segmentation, wherein the image enhancement and denoising adopt Gaussian filter denoising, and the Gaussian filter formula is: Wherein σ is the standard deviation, (x0, y0) is the kernel center; The crack edge detection and segmentation adopt Canny edge detection, where I(x, y) is the image gray value; G x ,G y is the gradient in x and y directions; S12, crack feature extraction and representation, key point detection is performed by using skeletonization algorithm Skeletonization is based on distance transformation: where C is the crack region, is the boundary, d(·) is the distance function; Crack feature parameters are extracted using contour tracing, where the direction vector θ of the contour points is used. i =arctan2(y i+1 -y i ,x i+1 -x i ), where (x i y i () represents a point on the contour; S13, crack propagation path tracking algorithm, intra-frame path connection (static analysis), path cost function is adopted: wherein is a path point, w(p i , p i+1 ) is a neighboring point distance cost, c(p i ) is a point credibility, and λ is a weight coefficient; a light flow method is adopted for cross-frame time sequence tracking, wherein a light flow constraint equation is I x u + I y v + I t = 0 where I x , y , t is the gradient of the image in the x, y directions and time t, (u, v) is the pixel motion vector; S14, expansion path optimization and model fitting, path smoothing and artifact removal are performed by using Bezier curve fitting, wherein the cubic Bezier curve is B(t) = (1 - t) 3 P0+ 3(1 - t) 2 tP1+ 3(1 - t)t 2 P2+ t 3 P2, t e [0, 1] Wherein P0, P1, P2, P3 are control points; Extension direction and rate modeling, extension rate calculation where L(t) is the crack length at time t and Δt is the time interval.

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