A stability link and method of making the same

Abstract

The present application relates to a kind of stability connecting rod and its preparation method, belong to mechanical component technical field.The present application discloses a kind of stability connecting rod, the stability connecting rod is composed of stability connecting rod body and manganese phosphate coating;The raw material of the connecting rod body includes 40CrMnMo, silicon carbide, graphite powder, wherein the total mass of silicon carbide, graphite powder accounts for 0.8~3% of the total mass of raw material.The present application further discloses a kind of preparation method of stability connecting rod, the preparation method of stability connecting rod includes in the surface of connecting rod body covering manganese phosphate coating, wherein stability connecting rod body is prepared by mixing after raw material powdering, then pre-pressing, sintering, hot forging, heat treatment, shot peening treatment, machining are sequentially carried out.The present application is prepared by simple, low-carbon method, and the stability connecting rod with long service life and corrosion resistance is prepared.

Description

Technical Field

[0001] This invention belongs to the field of mechanical component technology and relates to a stabilizing connecting rod and its manufacturing method. Background Technology

[0002] The connecting rod is the component connecting the piston and the crankshaft, consisting of three parts: the small end, the rod body, and the big end. Its function is to transmit the force on the piston to the crankshaft, converting the piston's reciprocating motion into the crankshaft's rotational motion. The connecting rod is a crucial component of the tractor's crank-connecting rod mechanism; it connects to the piston above and the crankshaft below. Its function is to transfer the enormous pressure on the piston to the crankshaft, causing the crankshaft to rotate and transfer the heat energy generated by fuel combustion, ultimately converting it into mechanical energy for external output.

[0003] During use, connecting rods often experience damage such as deformation, bending, twisting, and double bending; as well as wear and deformation at the large and small ends. Therefore, it is necessary to research a highly stable connecting rod to improve its service life. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by proposing a robust, durable, and corrosion-resistant stable connecting rod.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A stabilizing link, comprising a stabilizing link body and a manganese phosphate coating; the raw materials of the link body include 40CrMnMo, silicon carbide, and graphite powder, wherein the total mass of silicon carbide and graphite powder accounts for 0.8 to 3% of the total mass of the raw materials.

[0007] Silicon carbide has high hardness, and its addition can improve compressive strength, wear resistance and corrosion resistance; graphite powder can increase the carbon content in the raw materials and can also play a lubricating role in molten metal; the combined effect of silicon carbide and graphite powder can improve the overall performance of the connecting rod during sintering.

[0008] Preferably, the mass ratio of silicon carbide to graphite powder is (0.1-2):(0.1-2).

[0009] Preferably, the stabilizing link body includes a link small end, a link body, and a link big end, wherein the link small end adopts a hyperbolic curve.

[0010] Preferably, the pole body has an I-shaped cross-section.

[0011] The stabilizing link of the present invention has an I-shaped cross-section. Under the same cross-sectional area, the larger the moment of inertia of the cross-section, the higher the strength and stiffness. To achieve the same strength and stiffness, the larger the moment of inertia of the cross-section, the smaller the cross-sectional area, the less material is used, and the lighter the weight. In order to achieve lightweight and high strength and stiffness, the present invention preferably adopts a model with a large moment of inertia of the cross-section.

[0012] Preferably, the I-shaped cross-section of the rod gradually decreases from the big end to the small end of the connecting rod, and the area ratio of the big end to the small end of the connecting rod is (1.1~5):1.

[0013] Preferably, the thickness of the manganese phosphate coating is 0.5–30 μm, and the thickness of the manganese phosphate coating on the small end of the connecting rod is 15–40 μm.

[0014] A method for preparing a stabilizing connecting rod, the method comprising covering the surface of the connecting rod body with a manganese phosphate coating, wherein the stabilizing connecting rod body is prepared by mixing raw materials after powdering, and then sequentially performing pre-pressing, sintering, hot forging, heat treatment, shot peening, and machining.

[0015] This invention employs powder forging technology, which significantly reduces raw material and energy consumption compared to other metal processing methods. Furthermore, powder forging boasts high material utilization and minimal machining allowance, achieving a total material utilization rate exceeding 90% from raw powder to finished parts. It can directly produce complex-shaped products, and the precision and surface finish after forging can reach the levels of precision die forging and precision casting.

[0016] Preferably, the pre-compression process pressure is 300-900 MPa and the pressure holding time is 2-60 s.

[0017] Preferably, the sintering temperature is 1100–1600°C.

[0018] Preferably, the hot forging process includes hot forging the sintered connecting rod in a preheating mold at a preheating temperature of 200–500°C.

[0019] Further preferably, the hot forging pressure is 100-500 MPa.

[0020] Further preferably, the sintered connecting rod is pre-forged after preheating, with a preheating temperature of 300–400°C.

[0021] Preferably, the heat treatment process is carried out in two stages.

[0022] Further optimization involves a first-stage heat treatment process at 800–900°C, followed by oil cooling after heat preservation; and a second-stage heat treatment process at 500–750°C, followed by water cooling after heat preservation.

[0023] Preferably, the manganese phosphate coating is obtained by electrolytic phosphating.

[0024] Further optimization involves an electrolytic phosphating time of 1–500 s and a voltage of 1–120 V.

[0025] Preferably, the pH of the electrolytic phosphating solution is 1 to 4, and the reaction temperature is 5 to 35°C.

[0026] Electrolytic phosphating at low pH and low temperature can better ensure the stability and uniformity of the coating.

[0027] Preferably, the manganese ion content in the electrolytic phosphating solution is 2-150 g / L; the solvent includes nitric acid and / or citric acid and / or phosphoric acid.

[0028] Preferably, the electrolytic phosphating solution also includes one or more of borates, chlorates, and nitrites.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The stabilizing link of the present invention is composed of a stabilizing link body and a manganese phosphate coating, and has good mechanical properties and corrosion resistance.

[0031] 2. This invention uses powder forging technology, which reduces raw material and energy consumption while ensuring the accuracy of the stable connecting rod.

[0032] 3. This invention adds silicon carbide and graphite powder to the metal raw material powder to increase the corrosion resistance and mechanical properties of the stable connecting rod.

[0033] 4. The present invention uses electrolytic phosphating to ensure the stability and uniformity of the coating.

[0034] 5. This invention produces a stable connecting rod with a long service life and corrosion resistance through a simple and low-carbon method. Detailed Implementation

[0035] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0036] Unless otherwise specified, the materials used in this invention are commercially available products, and the methods used are conventional technical means.

[0037] The stabilizing link of the present invention consists of a stabilizing link body and a manganese phosphate coating;

[0038] The thickness of the manganese phosphate coating is 0.5–50 μm; the thickness of the manganese phosphate coating on the small end of the connecting rod is thicker than that on other parts, and the thickness of the manganese phosphate coating on the small end of the connecting rod is 15–50 μm.

[0039] The stabilizing link body includes a link small end, a link body, and a link big end, wherein the link body has an I-shaped cross-section and the link small end adopts a hyperbolic curve.

[0040] The fabrication process of the stabilizing link body includes:

[0041] 40CrMnMo is powdered (particle size 20-200 μm) and then mixed with silicon carbide and graphite powder in a mass ratio of (0.1-2):(0.1-2), wherein the total mass of silicon carbide and graphite powder added accounts for 0.8-3% of the total mass of raw materials.

[0042] The mixed powder is pre-compressed at a pressure of 300–900 MPa for a holding time of 2–60 s.

[0043] Then sintering is carried out at 1100-1600℃ to obtain the sintered workpiece;

[0044] The sintered workpiece is preheated and then pre-forged. The preheating temperature of the sintered workpiece is 300-400℃. The pre-forging process is carried out in a preheating mold with a temperature of 200-500℃. The hot forging pressure is 100-500MPa.

[0045] Then, heat treatment is carried out in two stages: the first stage temperature is 800-900℃, and after holding at this temperature, it is cooled with oil; the second stage temperature is 500-750℃, and after holding at this temperature, it is cooled with water.

[0046] After the workpiece cools, it undergoes shot peening and machining to treat the surface.

[0047] Then, a manganese phosphate coating is applied to the surface of the connecting rod body;

[0048] The manganese phosphate coating is obtained by electrolytic phosphating; the electrolytic phosphating time is 1-50s and the voltage is 1-50V.

[0049] The pH of the electrolytic phosphating solution is 1-4, and the reaction temperature is 5-35℃;

[0050] The manganese ion content in the electrolytic phosphating solution is 2-150 g / L; the solvent includes nitric acid and / or citric acid and / or phosphoric acid.

[0051] The electrolytic phosphating solution also includes one or more of borates, chlorates, and nitrites.

[0052] The resulting stable connecting rod has a tensile strength >1100 MPa; it can achieve corrosion resistance of more than 400 hours in a neutral salt spray chamber.

[0053] Example 1

[0054] The stabilizing link in this embodiment consists of a stabilizing link body and a manganese phosphate coating;

[0055] The manganese phosphate coating thickness is 10 μm;

[0056] The stabilizing link body includes a small end, a shaft, and a large end, wherein the shaft has an I-shaped cross-section, and the moment of inertia of the I-shaped cross-section is I. x :I y =2.4; The small end of the connecting rod adopts a hyperbolic curve.

[0057] The fabrication process of the stabilizing link body includes:

[0058] 40CrMnMo powder (particle size 50um) is mixed with silicon carbide and graphite powder at a mass ratio of 1.5:1, wherein the total mass of silicon carbide and graphite powder added accounts for 1.2% of the total mass of raw materials.

[0059] The mixed powder was pre-compressed at a pressure of 600 MPa for 8 seconds.

[0060] Then, sintering is carried out at 1430℃ to obtain the sintered workpiece;

[0061] The sintered workpiece is preheated and then pre-forged. The preheating temperature of the sintered workpiece is 360℃. The pre-forging process is carried out in a preheating mold at a temperature of 300℃. The hot forging pressure is 280MPa.

[0062] Then, heat treatment is carried out in two stages: the first stage temperature is 860℃, which is held at the temperature and then cooled with oil; the second stage temperature is 630℃, which is held at the temperature and then cooled with water.

[0063] After the workpiece cools, it undergoes shot peening and machining to treat the surface.

[0064] Then, a manganese phosphate coating is applied to the surface of the connecting rod body:

[0065] The manganese phosphate coating is obtained by electrolytic phosphating; the electrolytic phosphating time is 10s, the voltage is 23V; the pH of the electrolytic phosphating solution is 3-3.5, and the reaction temperature is 25-30℃; in the electrolytic phosphating solution, the manganese ion content in the manganese sulfate is 140g / L; the solvent includes nitric acid, phosphoric acid and citric acid in the same volume ratio; the electrolytic phosphating solution also includes 0.1% borate and 0.1% chlorate.

[0066] The resulting stable connecting rod has a tensile strength of 1172 MPa and can achieve corrosion resistance for 480 hours in a neutral salt spray chamber.

[0067] Example 2

[0068] Compared with Example 1, the difference lies in the moment of inertia I of the I-shaped cross-section. x :I y=2.6.

[0069] Compared to Example 1, the connecting rod in this example has a 3.7% increase in tensile strength under the same I-shaped cross-sectional area.

[0070] Example 3

[0071] Compared to Example 1, the difference is that the heat treatment process only involves the first stage.

[0072] The tensile strength of the resulting connecting rod decreased by 6.8%.

[0073] Example 4

[0074] Compared with Example 1, the difference is that the electrolytic phosphating process takes 20 seconds and the voltage is 15V.

[0075] The obtained manganese phosphate coating has a thickness of 3 μm and a corrosion resistance time of 360 h in a neutral salt spray chamber.

[0076] Comparative Example 1

[0077] Compared to Example 1, the difference is that it is not covered with a manganese phosphate coating.

[0078] The corrosion resistance time of the resulting connecting rod in the neutral salt spray chamber decreased significantly, but due to the addition of silicon carbide and graphite powder to the raw material system, its corrosion resistance was improved to some extent compared to 40CrMnMo alone.

[0079] Comparative Example 2

[0080] Compared with Example 1, the difference is that the raw material of the connecting rod body is only 40CrMnMo, without the addition of silicon carbide and graphite powder.

[0081] The tensile strength of the resulting connecting rod is only 992 MPa.

[0082] Comparative Example 3

[0083] Compared with Example 1, the difference is that the total amount of silicon carbide and graphite powder added to the raw materials of the connecting rod body is 0.2%.

[0084] The tensile strength of the resulting connecting rod is 1012 MPa.

[0085] In summary, this invention provides a long-lasting and corrosion-resistant stable connecting rod using a simple, low-carbon method. The stable connecting rod comprises a connecting rod body and a manganese phosphate coating. The raw materials for the connecting rod body include 40CrMnMo, silicon carbide, and graphite powder, with the total mass of silicon carbide and graphite powder accounting for 0.8–3% of the total mass of the raw materials. The thickness of the manganese phosphate coating is 0.5–50 μm.

[0086] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for manufacturing a stable connecting rod, characterized in that, include: 40CrMnMo powder with a particle size of 20~200μm obtained by pulverizing 40CrMnMo is mixed with silicon carbide and graphite powder in a mass ratio of (0.1~2):(0.1~2), wherein the total mass of silicon carbide and graphite powder added accounts for 0.8~3% of the total mass of raw materials. The mixed powder is pre-compressed at a pressure of 300-900 MPa for a holding time of 2-60 seconds. Then sintering is carried out at 1100~1600℃ to obtain the sintered workpiece; The sintered workpiece is preheated and then pre-forged. The preheating temperature of the sintered workpiece is 300~400℃. The pre-forging process is carried out in a preheating mold with a temperature of 200~500℃. The hot forging pressure is 100~500MPa. Then, heat treatment is carried out in two stages: the first stage temperature is 800~900℃, and after holding at the temperature, it is cooled with oil; the second stage temperature is 500~750℃, and after holding at the temperature, it is cooled with water. After the workpiece cools, it undergoes shot peening and machining to treat the surface and obtain the connecting rod body. Then, a manganese phosphate coating is applied to the surface of the connecting rod body; The manganese phosphate coating is obtained by electrolytic phosphating; the electrolytic phosphating time is 1~50s and the voltage is 1~50V. The pH of the electrolytic phosphating solution is 1~4, and the reaction temperature is 5~35℃; The manganese ion content in the electrolytic phosphating solution is 2~150 g / L; the solvent in the electrolytic phosphating solution includes nitric acid and / or citric acid and / or phosphoric acid; The electrolytic phosphating solution also includes one or more of borates, chlorates, and nitrites.

2. A stabilizing link, characterized in that, It is prepared by the method of claim 1 for making a stabilizing link, wherein the stabilizing link is composed of a stabilizing link body and a manganese phosphate coating; The connecting rod body includes a small end, a rod body, and a large end, wherein the rod body has an I-shaped cross-section and the small end of the connecting rod adopts a hyperbolic curve. The I-shaped cross-section of the rod gradually decreases from the big end to the small end of the connecting rod, and the area ratio of the big end to the small end of the connecting rod is (1.1~5):1; The thickness of the manganese phosphate coating is 0.5~50μm; the thickness of the manganese phosphate coating on the small end of the connecting rod is 15~50μm; The manganese phosphate coating on the small end of the connecting rod is thicker than that on other parts.