Processing technology for crankshafts with ceramic layers

Abstract

To prolong the lifetime of a crankshaft by decreasing the friction coefficient of a crankshaft surface, improving the wear resistance of the surface, and reducing scratching and seizing.SOLUTION: A processing technology for a crankshaft with a ceramic layer includes the steps of: dividing a journal of the crankshaft before spraying into a journal spray part 11 and two ground parts located on both sides thereof, where the journal ground parts 10 have surfaces higher than the surface of the journal spray part 11 and higher than a surface of a finished product, a fillet 2 before spraying has a surface higher than the surface of the finished product, and the dimension of the journal spray part is smaller than that of the finished product in a radial direction; and spraying a ceramic coating layer on the surface of the journal spray part and grinding the journal having the ceramic coating layer sprayed and the fillet surface until the ceramic coating layer and a fillet layer surface are joined seamlessly, and then polishing the same to obtain a crankshaft finished product.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to the technical field of crankshafts, in particular to the processing of crankshafts with a ceramic layer. [Background technology]

[0002] The crankshaft is one of the most important parts in an engine, and the reliability of the crankshaft leads to the stability of the whole machine. In recent years, with the implementation of Euro 6 emission standards and national 6 emission standards, engines have become lighter, more energy-efficient and faster, and the explosion pressure of the engine is constantly increasing. The maximum explosion pressure has already risen from 160-180 bar in national 5 emission standards to 200-260 bar in national 6 emission standards, and as a result, the risk of the crankshaft being scratched and failing is constantly increasing. Since the implementation of national 6 emission standards, the occurrence rate of scratches on the crankshaft of 4-6 cylinder engines has obviously increased, and the failure caused by scratches accounts for more than 30% of the total failure rate, becoming the main factor affecting the reliability of the engine. The main failure mechanism is that the explosion pressure of the engine increases, the actual pressure bearing of the crankshaft journal becomes larger, the hydrodynamic lubricating oil film becomes more easily broken, and the friction pair between the crankshaft and the bearing bush enters a boundary lubrication state, and the local metal micro-convex bodies of the friction pair come into direct contact with each other, causing serious wear and lubrication failure. Therefore, in order to improve the reliability of crankshafts, it is an urgent task to find a way to lower the surface friction coefficient of the crankshaft and reduce scratches and seizure on the crankshaft.

[0003] At present, the conventional surface treatment methods for crankshafts are mainly two types: surface induction hardening and surface nitriding. However, both of them increase the hardness difference between the friction pair between the journal and the bearing bush by increasing the surface hardness, but do not change the friction coefficient of the material itself, and do not fundamentally change the friction resistance of the crankshaft surface. Therefore, the conventional surface treatment technology for crankshafts can no longer meet the requirements of engines with higher emission standards, and there is an urgent need to research new technologies and methods to reduce the friction coefficient of the crankshaft surface, extend the life of the crankshaft, reduce scratches and seizure, and improve the reliability of the entire engine. Summary of the Invention [Problem to be solved by the invention]

[0004] To this end, the technical problem to be solved by the present invention is to provide a processing technology for a crankshaft with a ceramic layer, which overcomes the shortcomings of the prior art, reduces the friction coefficient of the crankshaft surface, improves the wear resistance of the crankshaft surface, reduces scratches and seizure failures, and extends the life of the crankshaft. [Means for solving the problem]

[0005] In order to solve the above technical problems, the present invention provides a step of dividing the journal of the crankshaft before spraying into a journal spraying section and two journal grinding sections located on both sides of the journal spraying section, wherein a surface of the journal grinding section is higher than a surface of the journal spraying section, a surface of the journal grinding section is higher than a journal surface of the finished crankshaft, a fillet surface of the crankshaft before spraying is higher than a fillet surface of the finished crankshaft, and a dimension of the journal spraying section is smaller than a dimension of the journal of the finished crankshaft in a journal radial direction; and spraying a ceramic coating layer onto the surface of the journal spraying portion, and grinding and polishing the journal surface and fillet surface of the crankshaft onto which the ceramic coating layer has been sprayed until the ceramic coating layer surface and the fillet surface are seamlessly joined to obtain a finished crankshaft.

[0006] Preferably, the fillet surface of the crankshaft before spraying is 0.1 mm to 0.15 mm higher than the fillet surface of the finished crankshaft, and the dimension of the journal spray portion is 0.1 mm to 0.15 mm smaller in the journal radial direction than the dimension of the journal of the finished crankshaft.

[0007] Preferably, the width of the journal ground portion perpendicular to the journal radial direction is 1 mm to 2 mm.

[0008] Preferably, the fillet surface of the crankshaft before blasting and the surface of the journal ground portion are joined seamlessly, and the joint between the journal ground portion and the journal blasted portion is arc-shaped.

[0009] Preferably, before spraying the ceramic coating layer onto the surface of the journal spraying portion, the crankshaft before spraying is subjected to pre-treatment including journal hardening, journal oil hole protection, and journal surface texturing treatment.

[0010] Preferably, the ceramic coating layer has a thickness in the radial direction of the journal of 0.05 mm to 0.2 mm.

[0011] Preferably, the step of spraying a ceramic coating layer on the surface of the journal spraying portion specifically includes: A metal adhesive undercoat layer having a thickness of 0.05 to 0.10 mm in the radial direction of the journal is sprayed onto the surface of the journal spraying portion, A uniform and dense ceramic coating layer is sprayed onto the surface of the journal spraying part, the spraying heat source temperature is set to 2000°C to 3500°C, and the surface temperature of the journal spraying part is set to 80°C to 150°C.

[0012] Preferably, the spraying distance when spraying the ceramic coating layer is 50 mm to 380 mm.

[0013] Preferably, the dimension of the journal after the grinding is 0.004 mm to 0.006 mm larger in the journal radial direction than the dimension of the journal of the completed crankshaft.

[0014] Preferably, the journal surface of the finished crankshaft has a roughness of 0.1 μm to 0.4 μm. Effect of the Invention

[0015] Compared with the prior art, the above technical solution of the present invention has the following advantages: The present invention provides a journal spraying section and a journal grinding section on the surface of the journal, sprays a ceramic coating layer of a certain thickness on the surface of the journal spraying section, and then grinds and polishes the journal surface to the design dimensions of the finished crankshaft. By spraying the ceramic coating layer, the wear resistance of the crankshaft is greatly improved, the friction coefficient of the crankshaft surface is reduced, the crankshaft lifespan is extended, and the probability of scratches and seizure is greatly reduced. [Brief description of the drawings]

[0016] In order to make the content of the present invention easier and clearer to understand, the present invention will be described in more detail hereinafter according to specific embodiments of the present invention with reference to the drawings. [Figure 1] 1 is a flow chart of a method of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a crankshaft prior to spraying according to the present invention. [Diagram 3] FIG. 3 is a partial enlarged view of part A in FIG. 2. [Figure 4] FIG. 2 is a schematic diagram of a finished crankshaft after spraying according to the present invention. [Diagram 5] FIG. 5 is a partially enlarged view of part B in FIG. [Figure 6] 2 is a schematic diagram of a crankshaft journal surface before spraying in an embodiment of the present invention. FIG. [Figure 7] 1 is a schematic diagram of a crankshaft journal surface sprayed with a ceramic coating layer in an embodiment of the present invention. [Figure 8] This is a completed 6-cylinder crankshaft onto which a ceramic coating layer is sprayed in accordance with an embodiment of the present invention. [Figure 9] 1 is a friction and wear test piece in an embodiment of the present invention. [Figure 10] FIG. 13 is a test result diagram of the center of the journal of a test piece to which no ceramic coating layer was sprayed in Test 2 in an embodiment of the present invention. [Figure 11] FIG. 13 is a test result diagram of the center part of the journal of a test piece sprayed with a ceramic coating layer in Test 2 in an embodiment of the present invention. [Figure 12] FIG. 11 is a test result diagram of upper and lower bearing bushings of test pieces not sprayed with a ceramic coating layer in Test 2 of an embodiment of the present invention. [Figure 13] FIG. 11 is a test result diagram of upper and lower bearing bushings of test pieces sprayed with a ceramic coating layer in Test 2 in an embodiment of the present invention. [Figure 14] FIG. 13 is a test result diagram of the center part of the journal of a test piece to which no ceramic coating layer was sprayed in Test 3 in an embodiment of the present invention. [Figure 15] FIG. 13 is a test result diagram of the center part of the journal of a test piece sprayed with a ceramic coating layer in Test 3 in an embodiment of the present invention. [Figure 16] FIG. 11 is a test result diagram of upper and lower bearing bushings of test pieces not sprayed with a ceramic coating layer in Test 3 in an embodiment of the present invention. [Figure 17]FIG. 11 is a test result diagram of upper and lower bearing bushings of test pieces sprayed with a ceramic coating layer in Test 3 in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will now be further described with reference to the drawings and specific embodiments so that those skilled in the art can better understand and practice the present invention, but the illustrative embodiments are not intended to limit the present invention.

[0018] In the description of the present invention, the orientations or positional relationships indicated by the terms "center," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inside," "outside," etc. are based on the orientations or positional relationships shown in the drawings, and are intended only to facilitate and simplify the description of the present invention, and do not indicate or suggest that the present invention must have a specific orientation, be configured, or operate in a specific orientation, and cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and are not understood to indicate or suggest relative importance or to implicitly indicate the number of technical features shown. Thus, a feature limited to "second" or "first" may explicitly or implicitly include one or more of the feature. In the description of the present invention, "multiple" means two or more, unless otherwise expressly and specifically limited.

[0019] In the present invention, unless otherwise expressly specified and limited, the terms "attach", "couple", "connect", "fixed" and the like should be understood in a broad sense, for example, may be a fixed connection, a detachable connection, or an integral connection, may be a mechanical connection, an electrical connection, a communication, may be a direct connection, an indirect connection through an intermediate medium, an internal communication between two elements, or an interactive relationship between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific situation.

[0020] Unless expressly specified and limited otherwise, a first feature being "on" or "under" a second feature may mean that the first feature is in direct contact with the second feature or that the first feature is in indirect contact with the second feature via an intermediate medium. Furthermore, the term "comprising" is intended to cover a non-exclusive inclusion, e.g., a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may further include unlisted steps or units, as appropriate, or may further include other steps or units inherent to those processes, methods, products, or apparatus.

[0021] As shown in the flow chart of FIG. 1, the present invention discloses a processing technique for a ceramic layered crankshaft, which includes the following steps:

[0022] Step 1: As shown in Figures 2-5, the dashed lines in Figures 2 and 3 indicate the surface 13 of the finished crankshaft (i.e., the surface on which the journal surface 6 of the finished crankshaft and the fillet surface 8 of the finished crankshaft are located), the solid lines in Figures 2-5 indicate the surface of the crankshaft before spraying (i.e., the surface on which the journal pre-spraying surface 5 is located), and the oblique lines in Figures 4 and 5 indicate the ceramic coating layer 9. Design the structure of the crankshaft before spraying. Define the dimensions of the finished crankshaft as the design dimensions of the crankshaft of the original engine, and divide the journal 1 of the crankshaft before spraying into a journal spraying section 11 having a width between the width between the journal and fillet contact point 3 on both sides and the width of the actual load surface of the bearing bush, and two journal grinding sections 10 located on both sides of the journal spraying section 11, respectively. The surface of the journal grinding portion 10 is higher than the surface of the journal spraying portion 11, the surface of the journal grinding portion 10 is higher than the journal surface 6 of the finished crankshaft, the surface of the journal grinding portion 10 is seamlessly joined to the fillet 2 surface of the crankshaft before spraying, the fillet 2 surface of the crankshaft before spraying is higher than the fillet surface 8 of the finished crankshaft, and the dimension of the journal spraying portion 11 is smaller in the radial direction of the journal 1 than the dimension of the journal 1 of the finished crankshaft. The clearance between the journal 1 of the completed crankshaft and the bearing bush is usually about 0.06 mm, and depending on the crankshaft, in this embodiment, the fillet 2 surface of the crankshaft before the blasting is 0.1 mm to 0.15 mm higher than the fillet surface 8 of the completed crankshaft, that is, the distance between the fillet pre-grinding surface 7 of FIG. 3 and the fillet surface 8 of the completed crankshaft is 0.1 mm to 0.15 mm. The dimension of the journal blasting portion 11 is 0.1 mm to 0.15 mm smaller than the dimension of the completed crankshaft in the radial direction of the journal 1. The width of the journal grinding portion 10 perpendicular to the radial direction of the journal 1 is 1 mm to 2 mm, and the sum of the widths of the two journal grinding portions 10 on both sides is 2 mm to 4 mm. The joint 12 between the journal grinding portion and the journal blasting portion is in an arc shape. The strength of the crankshaft can be ensured by the transition of the joint in an arc shape. In order to ensure good bonding at the joint between the journal ceramic coating layer 9 and the fillet 2 of the finished crankshaft, a certain amount of machining allowance is left on the fillet 2 before spraying, and after spraying is completed, both the fillet 2 and the ceramic coating layer of the journal 1 are ground to the dimensions of the finished product.

[0023] Step 2: The crankshaft before spraying is subjected to pre-treatment before spraying, including hardening the journal 1, protecting the oil supply hole of the journal 1, and texturing the surface of the journal 1. Step 2-1: The crankshaft hardening and pre-machining process is a normal production process and will not be mentioned further. Step 2-2: Before blasting, protect the oil holes of the crankshaft journal 1. The oil holes and oil hole chamfers of all spindle and connecting rod journal 1 are the protection areas from blasting, and the boundary of the protection area is the junction of the outer contour of the oil hole chamfer and the surface of the journal 1. Step 2-3: Texturing the surface of the journal 1. Prior to spraying, the surface of the journal spraying section 11 is subjected to a blasting treatment using sand particles to texture the surface and increase the bonding strength between the sprayed layer and the journal 1, and the surface roughness after texturing is set to Ra5 ​​μm to Ra10 μm.

[0024] Step 3: Spraying the ceramic coating layer 9. After the pretreatment, the ceramic coating layer 9 is sprayed onto the surface of the journal spraying portion 11, and only the surface of the journal spraying portion 11 of the journal 1 is sprayed, and the fillet 2 and other portions are not sprayed. Step 3-1: A metal adhesive underlayer for enhancing the bonding strength between the ceramic and the crankshaft base is sprayed to a thickness of 0.05 to 0.10 mm in the radial direction of the journal 1 onto the surface of the journal spraying section 11. The metal adhesive underlayer is an alloy material with Co, Ni, or Cr, Al, or Y added. Step 3-2: A uniform and dense ceramic coating layer 9 is sprayed onto the surface of the journal spraying section 11, with the spraying heat source temperature being 2000°C to 3500°C, the surface temperature of the journal spraying section 11 being 80°C to 150°C, and the radial thickness of the ceramic coating layer 9 on the journal 1 being 0.05mm to 0.2mm. When spraying the ceramic coating layer 9, the spraying distance is adjusted between 50 mm and 380 mm depending on the spraying material and spraying process. In this embodiment, a photograph of the crank journal 1 before spraying is shown in FIG. 6, and a photograph of the crank journal 1 after spraying is shown in FIG. 7. In this embodiment, ceramic is sprayed onto the surface of the crankshaft, and the porosity of the ceramic surface is stabilized to 5% to 7% by adjusting the material components and the spraying process. In this embodiment, the ceramic material may be a ceramic material mainly composed of alumina (Al2O3), or may be ZrO2 stabilized with Y2O3.

[0025] Step 4: Grind and polish to obtain the finished crankshaft. Step 4-1: The journal 1 surface, crank arm 4 surface and fillet 2 surface of the crankshaft sprayed with the ceramic coating layer 9 are ground by the same grinding machine until the ceramic coating layer 9 surface and the fillet 2 surface are seamlessly joined, the journal 1 dimension after grinding is 0.004mm~0.006mm, in this embodiment 0.005mm larger than the journal 1 dimension of the finished crankshaft in the journal 1 radial direction, and a CBN grinding wheel is used as the grinding tool. The journal and fillet surfaces of the crankshaft after spraying are ground at the same time, and the journal ceramic coating layer and the non-sprayed metal surface are seamlessly joined, which ensures a smooth transition between the journal of the crankshaft and the surface of the fillet part. Step 4-2: The surface is polished to obtain a finished crankshaft. The journal 1 and fillet 2 of the crankshaft are polished using a diamond belt in an automatic polishing machine, and the dimensions of the journal 1 and fillet 2 of the polished crankshaft are made to be the dimensions of the finished product, and the surface roughness of the journal 1 of the finished crankshaft is Ra0.1μm to Ra0.4μm.

[0026] After spraying, the present invention ensures that a ceramic coating layer of a certain thickness exists on the journal of the finished crankshaft, but the fillet remains a metal substrate, thereby improving the friction and wear resistance of the crankshaft journal and not compromising the strength of the crankshaft.

[0027] The present invention provides a journal surface with a journal spraying section and a journal grinding section, sprays a ceramic coating layer on the surface of the journal spraying section to a certain thickness, and then grinds and polishes the journal surface to the design dimensions of the finished crankshaft. The ceramic coating layer is sprayed to greatly improve the wear resistance of the crankshaft surface and reduce the friction coefficient of the crankshaft surface. The ceramic layer on the surface of the crankshaft with a ceramic layer significantly reduces the friction coefficient between the crankshaft and the bearing bush, and the high porosity of the ceramic layer enhances the lubricity of the journal surface, thereby greatly reducing the probability of the crankshaft scratching and seizing, and obviously extending its life. The main mechanisms by which the ceramic coating layer improves the tribological properties of the crankshaft and the bearing bush include: (1) By changing the type of contact material, the friction pair between the crankshaft journal and the bearing bush is converted from the original metal-metal pair to a ceramic-metal pair, which can greatly reduce the adhesion force of the friction pair caused by metal compatibility, lower the friction coefficient, and reduce the risk of adhesion wear. (2) Ceramic materials have a high porosity and have the ability to store oil in their microstructure. When the friction pairs are in a boundary lubrication state, the lubricating oil remaining in the pores of the material is forced out and overflows, significantly improving the lubrication performance of the surface. (3) The surface of the ceramic material reaches a mirror state after polishing, and the roughness is obviously reduced compared with that of traditional metal surfaces, reducing the risk of direct contact of local metal micro-convexities of the friction pair. (4) The damage to the ceramic material is small. During the process of wear, the ceramic material is once separated from the surface of the crankshaft base body and is very easily pulverized into powder. This avoids the wear of the three-body abrasive material caused by the falling off of the surface material, and the contamination of the friction surface is small.

[0028] To further explain the beneficial effects of the present invention, in this example, a crankshaft of a 6-cylinder engine as shown in Figure 8 was used as the research subject, and a rotational friction test was carried out using a friction and wear test piece having a ceramic coating layer on its surface obtained by the present invention and a conventionally manufactured test piece having no ceramic coating layer, and a photograph of the test piece used is shown in Figure 9. The friction and wear test piece having a ceramic coating layer on its surface obtained by the present invention and a conventionally manufactured test piece having no ceramic coating layer were each subjected to a rotational friction test under three types of test environments shown in Table 1, and the obtained test results are shown in Table 2.

[0029] JPEG0007634589000001.jpg55170

[0030] JPEG0007634589000002.jpg71170

[0031] In Figures 10 to 17, the journal holes are lubrication holes of the crankshaft journal, which the crankshaft itself has. Since the difference in the test results of Test 1 was not clear, Test 2 was continued. As can be seen from Figures 10 to 13, under the same test conditions, when a crankshaft with a ceramic coating layer of the present invention was used, the wear of the journal and the upper and lower bearing bushes was significantly improved. In Test 3, as can be seen from Figures 14 to 17, when a crankshaft with a ceramic coating layer of the present invention was used, the wear of the journal was also significantly improved, and scratches occurred on the upper and lower bearing bushes, but since the frictional heat generated was very small compared to a crankshaft without a ceramic coating layer, burning did not occur between the bearing bush and the cap, and the wear resistance was further improved.

[0032] From the overall view of Table 2, it can be seen that when the ceramic coating layer is sprayed, the wear of the journal of the crankshaft with the ceramic coating layer is obviously better than that of the crankshaft without the ceramic coating layer under the super-pressure load. When the contact friction occurs between the journal and the bearing bush, the heat caused by the friction of the crankshaft with the ceramic coating layer is obviously less than that of the crankshaft without the ceramic coating layer, and the journal and the bearing bush do not mesh in the crankshaft with the ceramic coating layer. In addition, the processing technology of the present invention is advanced and the process is feasible. Therefore, the test shows that the probability of scratches and seizure of the crankshaft with the ceramic coating layer is greatly reduced, and the function of the crankshaft with the ceramic coating layer obtained by the present invention is reliable, which proves the beneficial effect of the present invention.

[0033] The above embodiments are merely preferred embodiments given to fully explain the present invention, and the patent scope of the present invention is not limited thereto. Any equivalent replacement or modification made by a person skilled in the art based on the present invention is within the patent scope of the present invention. The patent scope of the present invention is subject to the scope of the claims. [Explanation of symbols]

[0034] 1. Journal 2. Fillet 3 Journal and fillet junction 4 Crank Arm 5 Journal surface before spraying 6 Journal surface of completed crankshaft 7 Surface before fillet grinding 8 Fillet surface of finished crankshaft 9 Ceramic coating layer 10 Journal grinding section 11 Journal spraying section 12 Junction between journal grinding section and journal blasting section 13 Surface of finished crankshaft

Claims

1. A processing technique for a crankshaft with a ceramic layer, comprising: a step of dividing the journal of the crankshaft before spraying into a journal spraying section and two journal grinding sections located on both sides of the journal spraying section, wherein a surface of the journal grinding section is higher than a surface of the journal spraying section, a surface of the journal grinding section is higher than a journal surface of the finished crankshaft, a fillet surface of the crankshaft before spraying is higher than a fillet surface of the finished crankshaft, and a dimension of the journal spraying section is smaller than a dimension of the journal of the finished crankshaft in a journal radial direction; spraying a metal adhesive underlayer having a thickness of 0.05-0.10 mm in the radial direction of the journal onto the surface of the journal spraying section, spraying a ceramic coating layer onto the surface of the journal spraying section, stabilizing the porosity of the surface of the ceramic coating layer to 5%-7% by adjusting the material components of the ceramic coating layer and the spraying process, and grinding and polishing the journal surface and fillet surface of the crankshaft sprayed with the ceramic coating layer until the ceramic coating layer surface and the fillet surface are seamlessly joined to obtain a finished crankshaft. Before the ceramic coating layer is sprayed onto the surface of the journal spraying portion, a pretreatment is performed on the crankshaft before spraying to protect the journal oil supply hole from the spraying of the ceramic coating layer. A processing technique for crankshafts with a ceramic layer, characterized in that

2. The processing technology for a crankshaft with a ceramic layer as described in claim 1, characterized in that the fillet surface of the crankshaft before spraying is 0.1 mm to 0.15 mm higher than the fillet surface of the finished crankshaft, and the dimensions of the journal sprayed portion are 0.1 mm to 0.15 mm smaller in the journal radial direction than the dimensions of the journal of the finished crankshaft.

3. 2. The processing technology for a crankshaft with a ceramic layer according to claim 1, characterized in that the width of the ground portion of the journal perpendicular to the radial direction of the journal is 1 mm to 2 mm.

4. A processing technology for a crankshaft with a ceramic layer as described in claim 1, characterized in that the fillet surface of the crankshaft before the spraying and the surface of the journal ground portion are seamlessly joined, and the joint between the journal ground portion and the journal sprayed portion is arc-shaped.

5. The processing technology for a crankshaft with a ceramic layer as described in claim 1, characterized in that before spraying a ceramic coating layer onto the surface of the journal spraying portion, the crankshaft before spraying is subjected to pre-treatment including journal hardening and texturing treatment of the journal surface.

6. A processing technology for a crankshaft with a ceramic layer as described in claim 1, characterized in that the thickness of the ceramic coating layer in the radial direction of the journal when the ceramic coating layer is sprayed is 0.05 mm to 0.2 mm.

7. The step of spraying a ceramic coating layer on the surface of the journal spraying portion specifically includes: A processing technology for a crankshaft with a ceramic layer as described in claim 1, characterized in that a uniform and dense ceramic coating layer is sprayed onto the surface of the journal spray portion, the spray heat source temperature is 2000°C to 3500°C, and the surface temperature of the journal spray portion is 80°C to 150°C.

8. 8. The treatment technology for a crankshaft with a ceramic layer according to claim 7, characterized in that the spraying distance when spraying the ceramic coating layer is 50 mm to 380 mm.

9. 2. The processing technology for a crankshaft with a ceramic layer according to claim 1, wherein the dimension of the journal after grinding is 0.004 mm to 0.006 mm larger in the journal radial direction than the dimension of the journal of the finished crankshaft.

10. The processing technique for a crankshaft with a ceramic layer according to any one of claims 1 to 9, characterized in that the roughness of the journal surface of the finished crankshaft is 0.1 μm to 0.4 μm.

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