A fastening connection part and its manufacturing method

Abstract

The present invention provides a fastening connection part and a manufacturing method thereof. The coating thickness δ1 of the joint surface of the fastening connection part satisfies the following conditions: 3Ra1 ≤ δ1 ≤ 1 / 3F; where Ra1 represents the surface roughness of the joint surface of the blank of the fastening connection part, and F represents the flatness of the joint surface of the blank of the fastening connection part, and F ≤ 500 μm. By controlling the coating thickness δ1 of the joint surface of the fastening connection part to satisfy 3Ra1 ≤ δ1 ≤ 1 / 3F, the present invention can ensure that the fastened connection part has both good anti-corrosion performance and fastening connection anti-loosening effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal surface coatings, and particularly relates to a fastening connection part and a manufacturing method thereof. Background Art

[0002] Connection refers to the combination of a connecting piece and a fastening connection part. The fastening connection part generally refers to various non-standard parts; common connecting pieces include fastening connection parts, also known as standard parts, which usually include the following 12 categories: bolts, studs, screws, nuts, self-tapping screws, wood screws, washers, retaining rings, pins, rivets, assemblies and coupling pairs, and welding nails. The connection between the fastening connection part and the fastened connection part is called a fastening connection, and the contact surface between the fastening connection part and the fastened connection part is called a joint surface.

[0003] The flatness of the joint surface is an important factor affecting the fastening connection effect of the fastening connection piece. In theory, the smaller the flatness value, the better the fastening effect. Due to different part forming processes, it is impossible to ensure that the flatness of any part joint surface is 100% consistent, and once the processing is completed, it is very difficult to change the flatness of the joint surface. Therefore, it is difficult to improve the fastening and loosening prevention effect by adjusting the flatness of the joint surface of the processed part. In addition, the coating thickness of the joint surface of the fastened connection part is also related to the loosening prevention effect of the fastening connection. The thicker the coating thickness, the greater the impact on the loosening prevention effect of the fastening connection, which is likely to cause the tightening torque to be untrue and the tightening torque to decay; when the coating thickness is relatively thin, although it can reduce the tightening torque decay to a certain extent, it will reduce the anti-corrosion ability of the coating for the fastening connection part. Summary of the Invention

[0004] In order to ensure that the fastening connection part has good anti-corrosion performance and fastening connection and loosening prevention effects at the same time, the present invention provides a fastening connection part and a manufacturing method thereof.

[0005] The technical solution provided by the present invention is specifically as follows:

[0006] In the first aspect, an embodiment of the present invention provides a fastening connection part, and the coating thickness δ1 of its joint surface satisfies the following conditions: 3Ra1 ≤ δ1 ≤ 1 / 3F; where Ra1 represents the surface roughness of the joint surface of the blank of the fastening connection part, F represents the flatness of the joint surface of the blank of the fastening connection part, and F ≤ 500 μm.

[0007] In combination with the first aspect, in an embodiment, the fastening connection part includes a combination of a bolt and a nut.

[0008] In combination with the first aspect, in an embodiment, 3.6 μm ≤ Ra1 ≤ 33 μm, 50 μm ≤ F ≤ 500 μm.

[0009] In combination with the first aspect, in one embodiment, the fastening and connecting part is a metal product.

[0010] In combination with the first aspect, in one embodiment, the forming method of the fastening and connecting part is a combination of one or more processes of casting, plastic forming, machining, welding, stamping and welding forming, powder metallurgy.

[0011] In combination with the first aspect, in one embodiment, the joint surface is the unprocessed surface or the processed surface of the part to be fastened and connected.

[0012] In combination with the first aspect, in one embodiment, the processed surface is a hot-rolled pickled surface or a machined surface.

[0013] In the second aspect, an embodiment of the present invention provides a manufacturing method for a fastening and connecting part, including the following steps:

[0014] Judge whether the flatness F of the joint surface of the blank of the fastening and connecting part is ≤500μm;

[0015] If the flatness F≤500μm, then judge whether the surface roughness Ra of the blank of the fastening and connecting part is ≤1 / 9F;

[0016] If Ra≤1 / 9F, the blank of the fastening and connecting part is integrally coated so that the overall thickness δ of the coating meets the preset thickness.

[0017] In combination with the second aspect, in one embodiment, after judging whether the flatness F of the joint surface of the blank of the fastening and connecting part is ≤500μm, it further includes: if the flatness F>500μm, then process the joint surface of the blank of the fastening and connecting part so that the flatness F≤500μm.

[0018] In combination with the second aspect, in one embodiment, after judging whether the surface roughness Ra of the blank of the fastening and connecting part is ≤1 / 9F, it further includes:

[0019] If Ra>1 / 9F and 3Ra>100μm, the joint surface and the non-joint surface are processed so that the surface roughness Ra1 of the joint surface of the blank of the fastening and connecting part is ≤1 / 9F, and the surface roughness Ra2 of the non-joint surface satisfies: 3Ra2≤100μm;

[0020] The joint surface and the non-joint surface of the blank of the fastening and connecting part are respectively coated so that the coating thickness δ1 of the joint surface satisfies: 3Ra1≤δ1≤1 / 3F, and the coating thickness δ2 of the non-joint surface satisfies: δ2≥3Ra2, and δ2-δ1≤100μm.

[0021] In combination with the second aspect, in one embodiment, after determining whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F, it further includes:

[0022] If Ra > 1 / 9F and 100μm ≥ 3Ra ≥ 10μm, the joint surface of the blank of the fastening connection part is processed so that the surface roughness Ra1 of the joint surface of the blank of the fastening connection part is ≤ 1 / 9F;

[0023] The joint surface and the non-joint surface of the blank of the fastening connection part are respectively coated so that the coating thickness δ1 of the joint surface satisfies 3Ra1 ≤ δ1 ≤ 1 / 3F, and the coating thickness δ2 of the non-joint surface is ≥ 3Ra.

[0024] In combination with the second aspect, in one embodiment, 3.6μm ≤ Ra1 ≤ 33μm and 50μm ≤ F ≤ 500μm.

[0025] In combination with the second aspect, in one embodiment, after determining whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F, it further includes:

[0026] If Ra > 1 / 9F and 3Ra < 10μm, the blank of the fastening connection part is integrally coated so that the overall thickness δ of the coating satisfies: 3Ra ≤ δ ≤ 10μm.

[0027] In combination with the second aspect, in one embodiment, when Ra ≤ 1 / 9F, the blank of the fastening connection part is integrally coated so that the overall thickness δ of the coating satisfies the preset thickness, including:

[0028] If Ra ≤ 1 / 50F, the blank of the fastening connection part is integrally coated to control the overall coating thickness δ of the blank of the fastening connection part to satisfy: 1 / 4F ≤ δ ≤ 1 / 3F.

[0029] In combination with the second aspect, in one embodiment, the preset thickness δ satisfies: 3Ra ≤ δ ≤ 1 / 3F.

[0030] The beneficial effects brought by the technical solutions provided by the embodiments of the present application include:

[0031] By controlling the coating thickness of the joint surface of the fastening connection part, the problem that it is difficult for the fastening connection part in the related art to have both good anti-corrosion performance and anti-loosening effect of the fastening connection is solved. Brief Description of the Drawings

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0033] Figure 1 is the axial force test result. Specific embodiments

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are some, rather than all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0035] First, some technical terms in this application are explained to facilitate the understanding of this application by those skilled in the art.

[0036] Blank of fastening connection parts: It refers to the fastening connection parts made by forming methods such as casting, plastic forming, cutting, welding, stamping and welding forming, powder metallurgy, etc., and without surface treatment.

[0037] Flatness: It refers to the deviation of the macroscopic uneven height of the substrate from the ideal plane. The flatness error is obtained by comparing the measured actual surface with the ideal plane, and the linear distance between the two is the flatness error value; or by measuring the relative height differences of several points on the actual surface and then converting to the flatness error value expressed in linear values.

[0038] Surface roughness: It refers to the smaller spacing and minute peak-valley unevenness on the machined surface. The distance (wave distance) between two wave peaks or two wave valleys is very small (less than 1 mm), which is difficult to distinguish with the naked eye, so it belongs to microscopic geometric shape error. The smaller the surface roughness, the smoother the surface. The size of the surface roughness has a great influence on the service performance of mechanical parts.

[0039] The embodiments of the present invention provide a fastening connection part, which can solve the problem that existing fastening connection parts are difficult to have both good anti-corrosion performance and fastening connection anti-loosening effect.

[0040] The embodiments of the present invention provide a fastening connection part, and the coating thickness δ1 of its joint surface satisfies the following conditions: 3Ra1 ≤ δ1 ≤ 1 / 3F; where Ra1 represents the surface roughness of the joint surface of the blank of the fastening connection part, F represents the flatness of the joint surface of the blank of the fastening connection part, and F ≤ 500 μm.

[0041] In one embodiment, the fastening connection part is a metal product, and its forming method is a combination of one or more processes of casting, plastic forming, machining, welding, stamping and welding forming, and powder metallurgy. The joint surface of the fastening connection part is an unprocessed surface or a processed surface. The processed surface is a hot-rolled pickled surface or a machined surface, and all meet the surface roughness Ra1≤1 / 9F of the joint surface.

[0042] In one embodiment, the fastening connection part includes a combination of a bolt and a nut.

[0043] In one embodiment, 3.6μm≤Ra1≤33μm and 50μm≤F≤500μm.

[0044] The embodiment of the present invention provides a manufacturing method of a fastening connection part, comprehensively considering the flatness and surface roughness of the joint surface of the fastening connection part, determining the coating thickness range according to the relationship between the flatness and the surface roughness, and thus selecting the correct coating process, so that the coated fastening connection part can meet the requirements of anti-loosening and anti-corrosion at the same time.

[0045] The manufacturing method of a fastening connection part provided by the embodiment of the present invention includes the following steps: judging whether the flatness F of the joint surface of the fastening connection part blank is ≤500μm; if the flatness F≤500μm, judging whether the surface roughness Ra of the fastening connection part blank is ≤1 / 9F; if Ra≤1 / 9F, the fastening connection part blank is integrally coated so that the overall thickness δ of the coating meets the preset thickness. Before treatment, the surface roughness Ra1 of the joint surface of the fastening connection part blank is the same as the surface roughness Ra of the entire part. When the flatness F≤500μm and Ra≤1 / 9F, the fastening connection part blank is integrally coated so that the overall thickness δ of the coating meets the preset thickness: 3Ra≤δ≤1 / 3F.

[0046] In one embodiment, the manufacturing method of a fastening connection part provided by the embodiment of the present invention includes the following steps: judging whether the flatness F of the joint surface of the fastening connection part blank is ≤500μm; if the flatness F≤500μm, judging whether the surface roughness Ra of the fastening connection part blank is ≤1 / 9F; if the flatness F>500μm, the joint surface of the fastening connection part blank is processed to make the flatness F≤500μm, and then judging whether the surface roughness Ra of the fastening connection part blank is ≤1 / 9F; when Ra≤1 / 9F, the fastening connection part blank is integrally coated so that the overall thickness δ of the coating meets the preset thickness. Whether the flatness F of the joint surface is ≤500μm has a great influence on the fastening effect. Once it is determined that the flatness F of the joint surface is >500μm, the joint surface needs to be machined to make the flatness F≤500μm, and the non-joint surface does not need to be processed.

[0047] In one embodiment, the embodiment of the present invention provides a manufacturing method for fastening connection parts, including the following steps: determining whether the flatness F of the joint surface of the blank of the fastening connection part is ≤ 500 μm; if the flatness F ≤ 500 μm, determining whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F; if Ra ≤ 1 / 9F, performing overall coating on the blank of the fastening connection part so that the overall thickness δ of the coating meets the preset thickness; if Ra > 1 / 9F and 100 μm ≥ 3Ra ≥ 10 μm, processing the joint surface of the blank of the fastening connection part so that the surface roughness Ra1 of the joint surface of the blank of the fastening connection part is ≤ 1 / 9F, and then respectively coating the joint surface and the non-joint surface of the blank of the fastening connection part so that the coating thickness δ1 of the joint surface meets 3Ra1 ≤ δ1 ≤ 1 / 3F and the coating thickness δ2 of the non-joint surface is ≥ 3Ra. When Ra > 1 / 9F and 100 μm ≥ 3Ra ≥ 10 μm, it indicates that the surface roughness Ra of the blank of the fastening connection part is relatively high, and the joint surface needs to be optimized to reduce the surface roughness of the joint surface. Then, the coating thickness δ1 of the joint surface is designed according to the reduced surface roughness of the joint surface, and it only needs to meet 3Ra1 ≤ δ1 ≤ 1 / 3F; the non-joint surface can be not processed, and when coating, it only needs to ensure that the coating thickness δ2 ≥ 3Ra.

[0048] In one embodiment, the embodiment of the present invention provides a manufacturing method for a fastening connection part, including the following steps: determining whether the flatness F of the joint surface of the blank of the fastening connection part is ≤ 500 μm; if the flatness F ≤ 500 μm, then determining whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F; if Ra > 1 / 9F and 3Ra > 100 μm, processing the joint surface and the non-joint surface so that the surface roughness Ra1 of the joint surface of the blank of the fastening connection part ≤ 1 / 9F and the surface roughness Ra2 of the non-joint surface satisfies: 3Ra2 ≤ 100 μm; respectively coating the joint surface and the non-joint surface of the blank of the fastening connection part so that the coating thickness δ1 of the joint surface satisfies: 3Ra1 ≤ δ1 ≤ 1 / 3F, and the coating thickness δ2 of the non-joint surface satisfies: δ2 ≥ 3Ra2 and δ2 - δ1 ≤ 100 μm. When the flatness F ≤ 500 μm, and Ra > 1 / 9F and 3Ra > 100 μm, it indicates that the flatness F of the joint surface meets the painting requirements, but the surface roughness Ra of the blank of the fastening connection part is too high. At this time, the joint surface and the non-joint surface are processed to reduce the surface roughness of the joint surface and the non-joint surface so that the surface roughness Ra1 of the joint surface of the blank of the fastening connection part ≤ 1 / 9F and the surface roughness Ra2 of the non-joint surface satisfies: 3Ra2 ≤ 100 μm. Then, the joint surface and the non-joint surface of the blank of the fastening connection part are respectively coated so that the coating thickness δ1 of the joint surface satisfies: 3Ra1 ≤ δ1 ≤ 1 / 3F, and the coating thickness δ2 of the non-joint surface satisfies: δ2 - δ1 ≤ 100 μm, as close to the lower limit as possible.

[0049] In one embodiment, the embodiment of the present invention provides a manufacturing method for a fastening connection part, including the following steps: determining whether the flatness F of the joint surface of the blank of the fastening connection part is ≤ 500 μm; if the flatness F ≤ 500 μm, then determining whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F; if Ra > 1 / 9F and 3Ra < 10 μm, performing overall coating on the blank of the fastening connection part so that the overall coating thickness δ satisfies: 3Ra ≤ δ ≤ 10 μm. The flatness F of the joint surface of the blank of the fastening connection part ≤ 500 μm indicates that the flatness F of the joint surface meets the painting requirements. When Ra > 1 / 9F and 3Ra < 10 μm, it indicates that both the surface roughness Ra of the blank of the fastening connection part and the flatness F of the joint surface are relatively low. At this time, no treatment is required for the blank of the fastening connection part, and overall coating is directly performed on the blank of the fastening connection part so that the overall coating thickness δ satisfies: 3Ra ≤ δ ≤ 10 μm. 3Ra ≤ δ can meet the anti-corrosion requirements, and when δ ≤ 10 μm, the influence of the coating thickness on the relaxation effect can be ignored.

[0050] In one embodiment, the embodiment of the present invention provides a manufacturing method for fastening connection parts, including the following steps: determining whether the flatness F of the joint surface of the blank of the fastening connection part is ≤ 500 μm; if the flatness F ≤ 500 μm, determining whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F; if Ra ≤ 1 / 50F, performing overall coating on the blank of the fastening connection part, and controlling the overall coating thickness δ of the blank of the fastening connection part to satisfy: 1 / 4F ≤ δ ≤ 1 / 3F. The flatness F of the joint surface of the blank of the fastening connection part ≤ 500 μm indicates that the flatness F of the joint surface meets the painting requirements. When Ra ≤ 1 / 50F, it indicates that the surface roughness Ra of the blank of the fastening connection part is relatively low. Performing overall coating on the blank of the fastening connection part and controlling the overall coating thickness δ of the blank of the fastening connection part to satisfy: 1 / 4F ≤ δ ≤ 1 / 3F; while the coating thickness meets the anti-corrosion requirements and is close to the upper limit of the anti-loosening requirements, it can achieve a better anti-corrosion effect.

[0051] In summary, the surface roughness of the joint surface is less than or equal to the surface roughness of other parts of the fastening connection part. When the surface roughness of both is the same, the coating thickness of the joint surface is controlled according to the upper limit, and the coating thickness of the entire part remains consistent. When the surface roughness Ra1 of the joint surface is less than the surface roughness Ra2 of the non-joint surface, the surface roughness Ra1 of the joint surface is less than or equal to the surface roughness of other parts of the fastening connection part, and the coating thickness of the entire part remains consistent. The coating thickness δ1 of the joint surface is the same as the coating thickness of other parts. When the surface roughness of the joint surface differs greatly from the surface roughness of other parts of the part, in order to ensure the fastening connection effect and the overall anti-corrosion performance of the part, the coating thickness of the joint surface and the coating thickness of other parts of the part should be controlled separately.

[0052] The technical solution of the present invention will be further described below through specific embodiments. The test methods used in the following embodiments:

[0053] The salt spray test is carried out in accordance with the salt spray test and rating method of EQCT-584-2007 Materials and Coatings 5-NaCl:

[0054] 1. Preparation of specimens

[0055] Unless otherwise specified, thoroughly clean the surface of each specimen before the test. Depending on the different properties of the cleaning object, the cleaning method may also vary, and some special requirements can be formulated. If the test specimen is cut from a workpiece with a coating, the coating near the cutting area shall not be damaged. Unless otherwise specified, an appropriate coating such as paint, paraffin or tape shall be used to protect the cutting area. In order to conduct a specific study on the specimen coating, some specifications require scribing the specimen to expose the base metal. The scribing method is given in the specification, except for the (or special) specifications that do not require scribing. All edges of the specimen, the parts in contact with the specimen holder, and the back surface of the specimen shall be edge-sealed and protected with a corrosion-resistant coating according to the required conditions.

[0056] 2. Method of placing the specimen

[0057] The position of the specimen in the salt spray chamber shall not be directly facing the spraying direction of the sprayer. The deflector plate shall be installed in advance to avoid direct spraying of the salt solution on the specimen surface. The test surface of the specimen shall be placed facing up in the salt spray chamber and inclined at 20° to the vertical direction. For irregular test specimens, such as the entire workpiece, it shall also be as close as possible to the above provisions. The specimen holder shall be made of non-metallic inert materials such as glass, plastic or wood coated with an appropriate coating. If the specimen needs to be suspended, the material used for suspension shall not be made of metal, but shall be synthetic fiber, cotton thread or other inert corrosion-resistant materials. The specimens shall be placed to ensure that they do not touch each other, and their test surfaces shall be located in the free circulation area of the salt spray. As long as the salt water does not flow onto the specimen or the specimen holder, the specimen or the holder can be placed at different horizontal positions in the salt spray chamber above the lowest water level.

[0058] 3. Test time

[0059] The test time is specified by the document (technical requirements, standards or drawings) related to the material or product. If there is no standard, it can be agreed upon by the relevant parties through negotiation. The recommended test periods are 2h, 6h, 24h, 48h, 96h, 168h, 240h, 480h, 720h, 1008h.

[0060] Test interruptions shall be minimized as much as possible. The salt spray chamber shall only be opened when it is necessary to briefly observe the test specimen, and the total time for opening the salt spray chamber every day shall not exceed 1h. If the test termination depends on the time when corrosion starts to appear, the test specimen shall be checked regularly according to the above requirements.

[0061] 4. Post-treatment

[0062] Non-organic coating test specimens: After the test of metal and / or inorganic coatings is completed, the test specimens are taken out. To reduce the shedding of corrosion products, the test specimens are placed indoors for natural drying for 0.5 h - 1 h before cleaning, and then gently cleaned with clean running water at a temperature not exceeding 40 °C to remove the residual salt spray solution on the surface of the test specimens. Then, they are immediately dried with air at a pressure not exceeding 200 kPa at a distance of about 300 mm from the test specimens. For organic coating test specimens without scratches, the organic coating test specimens without scratches should be rinsed with tap water, and the corrosion products and / or corrosion phenomena that should be evaluated should not be affected by the cleaning.

[0063] The axial force test is carried out in accordance with GB_T 16823.3-2010 Fasteners - Torque - Clamping Force Tests:

[0064] 1. After the computer is turned on, open the special software for the tightening torque and axial force equipment, and select the test program corresponding to the bolt to be measured for testing.

[0065] 2. Before the experiment starts, make sure the machine is in the test mode, that is, the key on the panel is in the "0" position and the emergency stop switch is in the unactivated state.

[0066] 3. During the process of testing bolts with different torques, it is necessary to replace the appropriate sensors and tooling according to the target axial force of different bolts. The recommended range of the sensor is more than 20% of the sensor range and should not be greater than the sensor range.

[0067] 4. Assemble the test specimens and conduct the test according to the software path of the equipment.

[0068] Example 1

[0069] This example provides a battery box bracket and its manufacturing method. The blank of the battery box bracket is a stamping and welding formed part, and the material used is hot-rolled pickled plate. The surface roughness Ra of the blank of the battery box bracket is measured to be 6.5 μm, and the flatness F of the joint surface is 400 μm.

[0070] From the above data, it can be judged that the flatness F of the joint surface of the blank of the battery box bracket is < 500 μm; the surface roughness Ra of the blank of the battery box bracket is ≤ 1 / 9F; the joint surface and non-joint surface of the blank of the battery box bracket are uniformly coated to make the coatings of the joint surface and non-joint surface consistent, and the thickness δ satisfies the condition: 3Ra ≤ δ ≤ 1 / 3F, that is, 19.5 μm ≤ δ ≤ 133 μm.

[0071] Since the flatness F of the joint surface of this battery box bracket is relatively large, the coating thickness δ can be controlled to be relatively thick. The powder coating or electrophoresis plus spraying can be selected as the coating process, which can ensure both anti-corrosion and anti-loosening requirements.

[0072] Example 2

[0073] This embodiment provides a joint surface between a drive shaft flange and a transmission flange and a manufacturing method thereof. The joint surface between the drive shaft flange and the transmission flange is a machined surface. Through testing, it is determined that its surface roughness Ra is 6 μm, and the flatness F of the joint surface is 100 μm.

[0074] From the above data, it can be judged that the flatness F of the joint surface of the drive shaft flange blank < 500 μm; the surface roughness Ra of the drive shaft flange blank ≤ 1 / 9F; the joint surface and the non-joint surface of the drive shaft flange blank are uniformly coated so that the coatings of the joint surface and the non-joint surface are consistent, and the thickness δ satisfies the condition: 3Ra ≤ δ ≤ 1 / 3F, that is, 18 ≤ δ ≤ 33 μm.

[0075] Since the variable range of the coating thickness δ is small and the thicknesses of the joint surface and the non-joint surface are the same, an electrophoretic coating process is preferably used.

[0076] Example 3

[0077] This embodiment provides a casting bracket and a manufacturing method thereof. The overall surface roughness Ra of the casting bracket is 20 μm, and the flatness of the joint surface is 100 μm.

[0078] From the above data, it can be judged that the flatness F of the joint surface of the casting bracket < 500 μm, and the surface roughness Ra > 1 / 9F; the joint surface is machined, and after machining, the surface roughness Ra1 of the joint surface is 6 μm, Ra1 ≤ 1 / 9F, the non-joint surface is not machined, and the surface roughness is still Ra = 20 μm; then the joint surface and the non-joint surface of the fastening connection part blank are respectively coated so that the coating thickness δ1 of the joint surface satisfies 3Ra1 ≤ δ1 ≤ 1 / 3F, that is, 18 μm ≤ δ1 ≤ 33 μm, and the coating thickness δ2 of the non-joint surface ≥ 3Ra, that is, δ2 ≥ 60 μm, and the minimum value is preferably taken.

[0079] In this embodiment, the coating thickness of the joint surface of the casting bracket cannot be kept consistent with the coating thickness of the non-joint surface and should be controlled separately. A composite process of first electrophoresing the part, then masking the joint surface, and then powder spraying or painting the whole part can be used.

[0080] Example 4

[0081] This embodiment provides a standard template part and a manufacturing method thereof. The overall surface roughness Ra of the standard template part is 6 μm, and the flatness of the joint surface is 240 μm.

[0082] From the above data, it can be determined that the flatness F of the joint surface of the standard part is less than 500 μm, and the surface roughness Ra is less than 1 / 9F; the joint surface and the non-joint surface are uniformly coated so that the coatings on the joint surface and the non-joint surface are consistent, and the thickness δ satisfies the condition: 3Ra ≤ δ ≤ 1 / 3F, that is, 18 μm ≤ δ ≤ 80 μm.

[0083] In this embodiment, electrophoresis is performed on the standard template parts to make the coating thicknesses of the joint surface and the non-joint surface consistent, and standard template parts with coating thicknesses of 6.5 μm, 10.3 μm, and 24.5 μm are obtained respectively. A salt spray test is uniformly carried out. The results show that when the coating thickness is 6.5 μm, the corrosion degree is serious; when the coating thickness is 10.3 μm, the corrosion degree is slightly lighter than that when the coating thickness is 6.5 μm; when the coating thickness is 24.5 μm, there is no visible corrosion on the parts to the naked eye.

[0084] In this embodiment, the standard template parts are uniformly coated to make the coating thicknesses of the joint surface and the non-joint surface consistent, and standard template parts with coating thicknesses of 50 μm, 100 μm, 150 μm, and 200 μm are obtained respectively. Axial force tests are carried out respectively. The bolts used for testing are M12 galvanized lubricated bolts, and the bolts are not reused; the test results are shown in Table 1 and Figure 1 :

[0085] Table 1 Axial force test results

[0086]

[0087] As shown in Table 1, according to the calculation of the fastening connection, the axial force is about 43000 N. After 24 hours, the attenuation degrees of the bolts on the standard template parts with coating thicknesses of 50 μm, 100 μm, 150 μm, and 200 μm are 6.8%, 8.3%, 11.2%, and 16.0% respectively, indicating that with the increase of the coating thickness, the attenuation degree increases.

[0088] The terms "comprising" and "having" and any variations thereof in the specification, claims and above-mentioned drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method including a series of steps is not limited to the listed steps, but may optionally further include steps not listed, or may optionally further include other steps inherent to these processes and methods. The descriptions of terms such as "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit that "first", "second" and "third" are different types.

[0089] In the description of the embodiments of the present application, terms such as "exemplary", "for example" or "for instance" are used to indicate examples, illustrations or explanations. Any embodiment or design solution described as "exemplary", "for example" or "for instance" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of terms such as "exemplary", "for example" or "for instance" is intended to present relevant concepts in a specific manner.

[0090] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall equally be included in the patent protection scope of the present application.

Claims

1. A fastening and connecting part, characterized in that: The coating thickness δ1 of its joint surface satisfies the following conditions: 3Ra1 ≤ δ1 ≤ 1 / 3F; where Ra1 represents the surface roughness of the joint surface of the blank of the fastening connection part, and F represents the flatness of the joint surface of the blank of the fastening connection part, and F ≤ 500μm.

2. The fastening connection part according to claim 1, characterized in that: 3.6μm ≤ Ra1 ≤ 33μm, 50μm ≤ F ≤ 500μm.

3. A manufacturing method of a fastening connection part, characterized in that, It includes the following steps: Judge whether the flatness F of the joint surface of the blank of the fastening connection part is ≤ 500μm; If the flatness F ≤ 500μm, then judge whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F; If Ra ≤ 1 / 9F, perform overall coating on the blank of the fastening connection part so that the overall thickness δ of the coating satisfies: 3Ra ≤ δ ≤ 1 / 3F.

4. The manufacturing method of the fastening connection part according to claim 3, characterized in that: After judging whether the flatness F of the joint surface of the blank of the fastening connection part is ≤ 500μm, it also includes: If the flatness F > 500μm, then process the joint surface of the blank of the fastening connection part so that the flatness F ≤ 500μm.

5. The manufacturing method of the fastening connection part according to claim 3, characterized in that: After judging whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F, it also includes: If Ra > 1 / 9F and 3Ra > 100μm, process the joint surface and the non-joint surface so that the surface roughness Ra1 of the joint surface of the blank of the fastening connection part is ≤ 1 / 9F, and the surface roughness Ra2 of the non-joint surface satisfies: 3Ra2 ≤ 100μm; Perform separate coating on the joint surface and the non-joint surface of the blank of the fastening connection part so that the coating thickness δ1 of the joint surface satisfies: 3Ra1 ≤ δ1 ≤ 1 / 3F, and the coating thickness δ2 of the non-joint surface satisfies: δ2 ≥ 3Ra2, and δ2 - δ1 ≤ 100μm.

6. The manufacturing method of the fastening connection part according to claim 3, characterized in that: After judging whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F, it also includes: If Ra > 1 / 9F and 100μm ≥ 3Ra ≥ 10μm, process the joint surface of the blank of the fastening connection part so that the surface roughness Ra1 of the joint surface of the blank of the fastening connection part is ≤ 1 / 9F; Perform separate coating on the joint surface and the non-joint surface of the blank of the fastening connection part so that the coating thickness δ1 of the joint surface satisfies 3Ra1 ≤ δ1 ≤ 1 / 3F, and the coating thickness δ2 of the non-joint surface ≥ 3Ra.

7. The manufacturing method of the fastening connection part according to claim 5 or 6, characterized in that: 3.6μm ≤ Ra1 ≤ 33μm, 50μm ≤ F ≤ 500μm.

8. The manufacturing method of the fastening connection part according to claim 3, characterized in that: After judging whether the surface roughness Ra of the blank of the fastening connection part is ≤ 1 / 9F, it also includes: If Ra > 1 / 9F and 3Ra < 10μm, perform overall coating on the blank of the fastening connection part so that the overall thickness δ of the coating satisfies: 3Ra ≤ δ ≤ 10μm.

9. The manufacturing method of the fastening connection part according to claim 3, characterized in that: The step of, if Ra ≤ 1 / 9F, performing overall coating on the blank of the fastening connection part so that the overall thickness δ of the coating satisfies: 3Ra ≤ δ ≤ 1 / 3F, includes: If Ra ≤ 1 / 50F, perform overall coating on the blank of the fastening connection part and control the overall coating thickness δ of the blank of the fastening connection part to satisfy: 1 / 4F ≤ δ ≤ 1 / 3F.

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