Bearing cap bolt machining method

Abstract

The invention relates to the field of bearing cap bolts, in particular to a bearing cap bolt machining method. The method comprises the following steps: 1, material modification; 2, main body forming, wherein main body forming of the bearing cover bolt is achieved through a cold heading technology; the machining precision of the bearing cover bolt is guaranteed by controlling the precision of each cold heading die in the cold heading process; 3, heat treatment; 4, thread rolling is conducted; 5, zinc plating passivation is carried out; step 6, appearance selection; 7, the rod diameter is fully detected; step 8, cleanliness detection; and step 9, packaging and warehousing. On the basis of machining of the high-precision upsetting die, high-precision machining of the bearing cover bolt can be achieved in a cold upsetting mode; in addition, traditional grinding machining can be replaced by a cold heading process; the production efficiency of the cold heading process is far higher than that of grinding machining, and the material utilization rate can be increased.

Description

Technical Field

[0001] The invention relates to the field of bearing cover bolts, in particular to a bearing cover bolt processing method. Background Art

[0002] The bearing cover bolts serve as the fastening bolts of the bearing cover and also have the functions of positioning and connection.

[0003] With the continuous development of the whole machine assembly process, multi-axis synchronous tightening and higher requirements for low noise and vibration of bearings, the precision requirements for bearing cover bolts are getting higher and higher.

[0004] During the production of traditional bearing cover bolts, due to the limitations of mold structure and process, in order to ensure the processing accuracy of the positioning dimensions of the bearing cover bolts, conventional bearing cover bolts generally need to use a grinding process to finely grind the bolt positioning rod diameter; while using a grinding process to ensure the positioning rod diameter accuracy of the bearing cover bolts requires a long grinding time and the production process is more complicated.

[0005] The existing patent 202221130798.8 - A kind of automobile cam bearing cover bolt does not clearly disclose the technical content for solving the above technical problems.

[0006] Therefore, in order to improve or solve at least one of the above problems, it is necessary to optimize the design of the existing bearing cap bolt processing method. Summary of the invention

[0007] The purpose of the invention is to provide a method for processing high-precision bearing cover bolts.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for processing a bearing cap bolt, the method comprising the following steps:

[0010] Step 1: Material modification: modify the metallographic structure, grain size, strength and size of the raw materials to meet the requirements of cold extrusion molding of bearing cover bolts;

[0011] Step 2: Main body forming, the main body of the bearing cap bolt is formed by cold heading process; the processing accuracy of the bearing cap bolt is ensured by controlling the accuracy of each cold heading die in the cold heading process;

[0012] Step 3: Heat treatment;

[0013] Step 4: Thread rolling;

[0014] Step 5: zinc passivation;

[0015] Step 6: Appearance selection;

[0016] Step 7: Full inspection of rod diameter;

[0017] Step 8: Cleanliness inspection;

[0018] Step 9: Packing and warehousing.

[0019] The cold heading process comprises the following steps:

[0020] S1: the first upsetting process; the raw material is subjected to the first upsetting operation by a cold upsetting die to form a preliminary upsetting material;

[0021] S2: second upsetting process; performing a second upsetting operation on the primary upsetting material through a cold upsetting die to form a secondary upsetting material;

[0022] S3: the third upsetting process; the secondary upsetting material is subjected to a third upsetting operation by a cold upsetting die to form a preform;

[0023] S4: the fourth upsetting process; the preform is subjected to a fourth upsetting operation by a cold upsetting die to form a bearing cap bolt body.

[0024] The cold forging die includes a plurality of process dies, and each forging process uses a process die to perform a corresponding forging operation;

[0025] Each process mold comprises a mold body, and the mold body is provided with an inner mold hole.

[0026] In the third upsetting step, the end of the inner die hole of the process die is chamfered.

[0027] In the fourth upsetting step, the inner die hole of the process die is designed to be in the shape of an inverted frustum.

[0028] At least in the fourth upsetting step, the inner die hole accuracy of the process die reaches 0.003 mm.

[0029] The dies for each process in the cold heading process are all made of gradient tungsten steel or gradient alloy.

[0030] In step 3, phosphorus removal is required first, followed by heat treatment.

[0031] During the mold processing of each process: the inner mold hole needs to be polished; the steps of polishing the inner mold hole are as follows:

[0032] A1: Rough polishing;

[0033] A2: Semi-fine polishing;

[0034] A3: Fine polishing;

[0035] A4:Mirror polished.

[0036] Before polishing the inner die hole, the polishing allowance of the inner die hole is required to be at least 0.02mm.

[0037] The advantages of the present invention are:

[0038] The invention discloses a bearing cover bolt processing method.

[0039] The invention is based on the processing of a high-precision upsetting die and can realize high-precision processing of the bearing cover bolt by cold upsetting.

[0040] In addition, the present invention can replace the traditional grinding process by cold heading process.

[0041] The production efficiency of cold heading process is much higher than that of grinding, and it can also improve material utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The following is a brief description of the contents expressed in each of the drawings in the specification of the present invention:

[0043] Figure 1 It is a process diagram of cold heading of bearing cover bolts in the present invention.

[0044] Figure 2 It is a process diagram of a cold heading die in the cold heading process of the present invention. DETAILED DESCRIPTION

[0045] The specific implementation of the present invention will be further explained in detail below by describing the optimal embodiment with reference to the accompanying drawings.

[0046] A method for processing a bearing cap bolt, the method comprising the following steps:

[0047] Step 1: Material modification: modify the metallographic structure, grain size, strength and size of the raw materials to meet the requirements of cold extrusion molding of bearing cover bolts;

[0048] Step 2: Main body forming, the main body of the bearing cap bolt is formed by cold heading process; the processing accuracy of the bearing cap bolt is ensured by controlling the accuracy of each cold heading die in the cold heading process;

[0049] Step 3: Heat treatment;

[0050] Step 4: Thread rolling;

[0051] Step 5: zinc passivation;

[0052] Step 6: Appearance selection;

[0053] Step 7: Full inspection of rod diameter;

[0054] Step 8: Cleanliness inspection;

[0055] Step 9: Packing and warehousing.

[0056] The invention is based on the processing of a high-precision upsetting die and can realize high-precision processing of the bearing cover bolt by cold upsetting.

[0057] In addition, the present invention can replace the traditional grinding process by cold heading process.

[0058] The production efficiency of cold heading process is much higher than that of grinding, and it can also improve material utilization.

[0059] Specifically, the bearing cap bolt processing method of the present invention mainly includes the following contents:

[0060] 1. Material modification: This step involves pre-processing the raw materials to ensure that their physical and chemical properties meet the requirements of subsequent processing;

[0061] This may include heat treatment, forging or other methods to change the material's metallographic structure, grain size, strength and size;

[0062] 2. Main body forming: The main part of the bearing cap bolt is formed by cold heading process;

[0063] Cold heading is a metal forming process that plastically deforms metal in a die by applying pressure to it at room temperature;

[0064] Controlling the accuracy of the cold heading die is the key to ensuring the machining accuracy of the bearing cap bolts;

[0065] 3. Heat treatment: This step may include processes such as annealing, normalizing, quenching and tempering to improve the mechanical properties of the material, such as hardness, toughness and wear resistance;

[0066] 4. Thread rolling: Processing threads on the bolt body of the bearing cap bolt, which is usually done by a thread rolling machine, which contacts the bolt through the thread rolling plate to form threads;

[0067] 5. Galvanizing passivation: This step involves coating the surface of the bearing cap bolts with a layer of zinc to provide corrosion protection;

[0068] Passivation is a post-galvanizing treatment to improve the corrosion resistance of the zinc coating;

[0069] 6. Appearance selection: Check the appearance of the processed bearing cap bolts and remove defective products;

[0070] 7. Full inspection of rod diameter: Fully inspect the rod diameter of the bearing cover bolts to ensure that its size meets the design requirements;

[0071] 8. Cleanliness test: Check the cleanliness of the bearing cover bolts to ensure that there is no residual cutting fluid, dust or other contaminants;

[0072] 9. Packaging and warehousing: Finally, the qualified bearing cap bolts are packaged and stored in the warehouse, ready for shipment or further use.

[0073] Furthermore, the cold heading process in the present invention comprises the following steps:

[0074] S1: the first upsetting process; the raw material is subjected to the first upsetting operation by a cold upsetting die to form a preliminary upsetting material;

[0075] S2: second upsetting process; performing a second upsetting operation on the primary upsetting material through a cold upsetting die to form a secondary upsetting material;

[0076] S3: the third upsetting process; the secondary upsetting material is subjected to a third upsetting operation by a cold upsetting die to form a preform;

[0077] S4: the fourth upsetting process; the preform is subjected to a fourth upsetting operation by a cold upsetting die to form a bearing cap bolt body.

[0078] The cold upsetting process disclosed in the present invention can realize the upsetting forming of the bearing cover bolts.

[0079] Specifically, the cold heading process of the bearing cap bolts in the present invention is a multi-stage cold forming process, and each step is precisely controlled to ensure the quality and performance of the final product.

[0080] Detailed explanation of cold heading process steps:

[0081] S1: First upsetting process:

[0082] In this step, the raw material is subjected to the first upsetting operation using a cold heading die.

[0083] The purpose of this operation is to cause the material to undergo plastic deformation in the die to form a preliminary upsetting material.

[0084] This stage may include the initial shaping of the bars or the creation of other basic shapes.

[0085] S2: Second upsetting process:

[0086] Next, a second upsetting operation is performed on the preliminary upsetting material formed by the first upsetting process using a cold upsetting die.

[0087] This step will further change the shape of the material, forming a secondary upset, which may involve further forming of the bolt head, rod or other intermediate products.

[0088] S3: The third upsetting process:

[0089] In this step, the secondary upsetting material is subjected to a third upsetting operation using a cold upsetting die.

[0090] This operation processes the material further to form a preform. This stage may include the initial forming of bearing cap bolts or the creation of other complex shapes.

[0091] S4: The fourth upsetting process:

[0092] Finally, the preform is subjected to a fourth upsetting operation using a cold upsetting die to ultimately form the bearing cap bolt body.

[0093] This step is the final forming stage, ensuring that the bolts reach the required size and shape, including the precise forming of the bearing cap bolts and the determination of other critical dimensions.

[0094] Throughout the cold heading process, each step requires precise die design and process control to ensure product quality and performance.

[0095] The advantages of the cold heading process include high efficiency, low cost, high material utilization, and the ability to produce parts with complex shapes and precise dimensions.

[0096] Additionally, material hardening during cold heading can improve the strength and wear resistance of the finished product.

[0097] Through this process, the bearing cap bolts can achieve high precision and high performance requirements without the need for subsequent large-scale cutting.

[0098] Specific cold heading process embodiment 1:

[0099] The cold heading process includes the following steps:

[0100] S0: cutting to obtain the blank length of the required volume of the bearing cap bolt blank;

[0101] S1: Strong shrinkage, using closed shrinkage to complete the forming of thread blank diameter and length;

[0102] S2: Preforming the head, pre-upsetting the head into a cylinder, and chamfering the end of the thread blank to prepare for the subsequent station to shrink and extrude the hexagon;

[0103] S3: shrinking the hexagon, shrinking and extruding the head cylinder, and preliminarily completing the hexagonal formation of the head;

[0104] S4: Final upsetting, final upsetting of the head and reduction of the rod diameter to complete the blank shape of the product.

[0105] Furthermore, the cold heading die described in the present invention includes multiple process dies, and each upsetting process uses a process die to perform the corresponding upsetting operation; each process die includes a die body, and the die body is provided with an inner die hole; in the cold upsetting process, each upsetting process requires a special die, and these die are called process die.

[0106] Each process tool is designed for a specific forming step to ensure that the material is deformed precisely at each stage.

[0107] One process die for each upsetting process: Each upsetting process is operated with a corresponding process die; this means that from the first upsetting process to the fourth upsetting process, each process has a dedicated die to ensure that accurate shape and size can be achieved at each stage.

[0108] Mold body and inner mold hole: Each process mold includes a mold body, which is the main structural part of the mold, and it provides the strength and stability of the mold; the mold body is provided with an inner mold hole, which is the key part for guiding and forming the material.

[0109] The shape and size of the inner die hole are designed according to the specific requirements of the part to be formed to ensure that the material can undergo the expected plastic deformation when passing through the inner die hole.

[0110] The design of the inner die hole must be very precise because it directly affects the dimensional accuracy and shape of the final product.

[0111] Coordinated use of process dies: During the cold heading process, the material will pass through the inner die holes of these process dies in sequence. Each process die will impose a specific deformation on the material to gradually form the final product shape.

[0112] Furthermore, in the third upsetting process described in the present invention, the end of the inner die hole of the process die is provided with a chamfer; the three-stage die is provided with a chamfer, which can solve the problem of the concavity of the middle rod after cold upsetting.

[0113] Furthermore, in the fourth upsetting process described in the present invention, the inner die hole of the process die is designed to be an inverted cone shape; based on such a design, the life of the die can be improved; the conical die structure can better withstand impact force and reduce die wear due to its design advantages, thereby improving the service life of the die; improving product shape and dimensional accuracy; the conical die can help to more accurately control the final shape and size of the product.

[0114] Furthermore, in the present invention, at least the inner die hole accuracy of the process die in the fourth upsetting process reaches 0.003 mm; based on this design, the accuracy of the final upsetting forming of the bearing cover bolt can be guaranteed.

[0115] Furthermore, in the cold heading process described in the present invention, each process mold is made of gradient tungsten steel or gradient alloy SG50; such a setting can ensure the service life of the process mold.

[0116] Furthermore, in step 3 of the present invention, it is required to remove phosphorus first and then perform heat treatment; the purpose of removing phosphorus first and then performing heat treatment is to remove the phosphate film remaining on the surface of the cold heading blank, to prevent the product from producing a hard and brittle film layer after heat treatment due to the residual phosphate film, and to cause phosphorus embrittlement during service; to improve its mechanical properties and service life, and at the same time improve its surface quality and corrosion resistance; high-strength bolts must be dephosphorized before heat treatment to prevent phosphate residues from affecting the performance of the heat treatment process.

[0117] Furthermore, in each process of the mold processing in the present invention, the inner mold hole needs to be polished; the steps of polishing the inner mold hole are as follows:

[0118] A1: Rough polishing;

[0119] A2: Semi-fine polishing;

[0120] A3: Fine polishing;

[0121] A4:Mirror polished.

[0122] Detailed explanation of the inner die hole polishing steps:

[0123] A1: Rough polishing: Rough polishing is the first step in the polishing process, the purpose of which is to remove burrs, oxide layers and other surface defects on the surface of the inner die hole.

[0124] This step usually uses a coarser polishing tool to quickly remove material and lay the foundation for subsequent polishing steps.

[0125] A2: Semi-finishing polishing: After rough polishing, the purpose of semi-finishing polishing is to further smooth the surface of the inner die hole and reduce the scratches caused by the rough polishing process.

[0126] This step uses a finer polishing tool than the rough polishing to further refine the surface texture.

[0127] A3: Fine polishing: Fine polishing is a key step in the polishing process, the purpose of which is to obtain a very smooth and uniform surface.

[0128] In this step, the polishing tools or compounds used are more delicate to ensure that the mold surface achieves the required finish and precision.

[0129] A4: Mirror polishing: Mirror polishing is the last step in the polishing process, the purpose is to achieve a highly reflective and smooth surface, similar to a mirror.

[0130] This step requires the use of very fine polishing materials, such as diamond paste or special polishing fluids, to achieve an extremely high surface finish.

[0131] Furthermore, in the present invention, before polishing the inner mold hole, the inner mold hole polishing allowance is required to be at least 0.02 mm; based on this design, requiring the inner mold hole polishing allowance to be at least 0.02 mm means that before polishing, the size of the inner mold hole needs to be 0.02 mm smaller than the final required size; this allowance is to ensure that any burrs, unevenness or other defects on the surface can be removed during the polishing process, while ensuring the dimensional accuracy and surface finish of the final product.

[0132] By strictly controlling the size and polishing process of the inner die hole before polishing, the quality of the cold heading die and the processing quality of the bearing cap bolts can be ensured, thereby improving the reliability and performance of the product.

[0133] Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. A method for processing a bearing cap bolt, characterized in that: The processing method comprises the following steps: Step 1: Material modification: modify the metallographic structure, grain size, strength and size of the raw materials to meet the requirements of cold extrusion molding of bearing cover bolts; Step 2: Main body forming, the main body of the bearing cap bolt is formed by cold heading process; the processing accuracy of the bearing cap bolt is ensured by controlling the accuracy of each cold heading die in the cold heading process; Step 3: Heat treatment; Step 4: Thread rolling; Step 5: zinc passivation; Step 6: Appearance selection; Step 7: Full inspection of rod diameter; Step 8: Cleanliness inspection; Step 9: Packing and warehousing.

2. A method for processing a bearing cap bolt according to claim 1, characterized in that: The cold heading process comprises the following steps: S1: the first upsetting process; the raw material is subjected to the first upsetting operation by a cold upsetting die to form a preliminary upsetting material; S2: second upsetting process; performing a second upsetting operation on the primary upsetting material through a cold upsetting die to form a secondary upsetting material; S3: the third upsetting process; the secondary upsetting material is subjected to a third upsetting operation by a cold upsetting die to form a preform; S4: the fourth upsetting process; the preform is subjected to a fourth upsetting operation by a cold upsetting die to form a bearing cap bolt body.

3. A method for processing bearing cap bolts according to claim 2, characterized in that: The cold forging die includes a plurality of process dies, and each forging process uses a process die to perform a corresponding forging operation; Each process mold comprises a mold body, and the mold body is provided with an inner mold hole.

4. A method for processing a bearing cap bolt according to claim 3, characterized in that: In the third upsetting step, the end of the inner die hole of the process die is chamfered.

5. A method for processing bearing cap bolts according to claim 3, characterized in that: In the fourth upsetting step, the inner die hole of the process die is designed to be an inverted frustum.

6. A method for processing bearing cap bolts according to claim 3, characterized in that: At least in the fourth upsetting step, the inner die hole accuracy of the process die reaches 0.003 mm.

7. A method for processing bearing cap bolts according to claim 3, characterized in that: The dies for each process in the cold heading process are all made of gradient tungsten steel or gradient alloy.

8. A method for processing bearing cap bolts according to claim 1, characterized in that: In step 3, phosphorus removal is required first, followed by heat treatment.

9. A method for processing bearing cap bolts according to claim 3, characterized in that: During mold processing in each process: The inner die hole needs to be polished; The inner die hole polishing steps are as follows: A1: Rough polishing; A2: Semi-fine polishing; A3: Fine polishing; A4:Mirror polished.

10. A method for processing bearing cap bolts according to claim 9, characterized in that: Before polishing the inner die hole, the polishing allowance of the inner die hole is required to be at least 0.02mm.

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