Inner end face high-precision grinding method, grinding standard block, and standard block preparation method

Abstract

The application discloses an inner end face high-precision grinding method, a grinding standard block, and a standard block preparation method. A part to be ground is placed between upper and lower grinding discs of a double-sided grinding machine, and a grinding standard block with two parallel plane end faces is additionally placed in a closed space formed between the inner end face of the part to be ground and the lower grinding disc. Then, the upper and lower grinding discs are used to implement double-sided, short-time, high-speed and grinding fluid-free flat grinding on the part to be ground, so that one plane end face of the grinding standard block is in contact with the inner end face of the part to be ground for grinding. The grinding standard block is prepared by coating a diamond film on a silicon carbide ceramic after double-sided grinding. The application solves the problem of high-precision grinding of the inner end face of the part.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically a high-precision grinding method for inner end faces, a grinding standard block for use, and a method for preparing the grinding standard block. Background Technology

[0002] like Figure 1 The part shown requires grinding of its inner end face (here, the inner end face is relative to the outer end face; when the end face of the part is not a complete plane, but has a portion recessed inward, the bottom surface of the recessed area is the inner end face, and the end face without the recess is called the outer end face). During the high-precision grinding (flatness 0.0012) of its inner end face, a high amount of heat (energy) is generated when the grinding motion removes metal, and almost all of the energy is concentrated in the grinding zone. This generated high temperature can cause various forms of thermal damage to the part surface, such as burns, harmful surface tensile stress, microstructure (metallographic) transformation, possible surface layer modification (formation of a secondary hardened layer, or surface annealing softening, etc.), surface cracks, reduced fatigue strength, and surface deformation caused by thermal expansion. While this effect can be mitigated with effective measures when grinding the outer end face, achieving high-quality grinding of the inner end face becomes a significant challenge due to the difficulty in dissipating heat. Summary of the Invention

[0003] This invention aims to provide a high-precision grinding method for inner end faces, as well as a grinding standard block and a standard block preparation method, which can effectively solve the problems existing in the current inner end face grinding, and achieve the purpose of short grinding time, high speed, good grinding effect and minimal heat generation.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] High-precision grinding methods for inner end faces include:

[0006] The part to be ground is placed between the upper and lower grinding discs of a double-sided grinding machine. A grinding standard block with two parallel flat end faces is placed in the closed space formed between the inner end face of the part to be ground and the lower grinding disc. Then, the upper and lower grinding discs perform double-sided, short-time, high-speed, and fluid-free flat grinding on the part to be ground, so that one flat end face of the grinding standard block contacts and grinds the inner end face of the part to be ground.

[0007] Furthermore, the parallelism and flatness of the two parallel plane end faces of the grinding standard block are both less than the parallelism and flatness of the inner end face of the part to be ground, that is, the precision is higher.

[0008] Furthermore, the surfaces of the upper and lower grinding discs are made of abrasive-free velvet.

[0009] Further, the flat end face of the grinding standard block, which is in contact with the inner end face of the part to be ground, is provided with a diamond coating.

[0010] The material density of the grinding standard block is less than the material density of the part to be ground.

[0011] The inner end face grinding standard block comprises a base body, the maximum outer diameter of the base body is less than the minimum inner diameter of the closed space formed between the inner end face and the outer end face of the part to be ground, and the base body comprises two parallel flat end faces.

[0012] Further, the base body is annular.

[0013] Further, the base body is made of silicon carbide ceramic material.

[0014] The preparation method of the inner end face grinding standard block comprises the following steps:

[0015] Step 1: selecting the material of the grinding standard block and determining the maximum outer diameter of the grinding standard block according to the minimum inner diameter of the closed space formed between the inner end face and the outer end face of the part to be ground;

[0016] Step 2: placing the base body on a double-sided grinding machine, using an upper grinding disc and a lower grinding disc with abrasive particles to double-side flat grind the two parallel flat end faces of the base body;

[0017] Step 3: cleaning the base body after double-side flat grinding;

[0018] Step 4: optionally performing diamond coating treatment on one of the two parallel flat end faces of the base body.

[0019] Further, in step 2, the parallelism and flatness of the two parallel flat end faces after double-side flat grinding are less than the parallelism and flatness requirements of the inner end face of the part to be ground.

[0020] The grinding standard block coated with a diamond ultra-thin film layer is adopted to realize high-precision grinding of the inner end face of the part, and the problem of inner end face grinding is solved.

[0021] The double-side grinding machine for grinding the outer end face is ingeniously adopted, the diamond thin film grinding standard block with higher flatness requirement of the workpiece, good cutting effect and dry grinding (without grinding fluid) is prepared, and high-precision inner end face grinding is realized.

[0022] Compared with the prior art, the present application has the following characteristics:

[0023] (1) Due to the use of short-time, high-speed dry grinding, the heat generated by grinding has not accumulated to the extent that it affects the performance of the parts (the heat generated is very small and not enough to make the parts heat up quickly), and the inner end face has reached the required flatness. Therefore, it has solved the high-temperature damage caused by excessive heat accumulation and heat concentration during traditional long-term grinding.

[0024] (2) Because the grinding standard block has two parallel flat end faces and the material density is lower than that of the part material (resulting in the grinding standard block being very light), it floats under the drive of the grinding disc of the double-sided grinding machine. During grinding, only the diamond coating layer contacts the inner end face of the part to be ground, and the surface of the lower grinding disc does not contact the flat end face of the grinding standard block.

[0025] (3) Since the maximum outer diameter of the grinding standard block is smaller than the minimum inner diameter of the closed space formed between the inner end face and the outer end face of the part to be ground, the grinding standard block rotates at high speed to grind the inner end face while also translating along the inner end face plane, thereby randomly and uniformly grinding all the inner end face surfaces (since the grinding standard block is very light and the grinding time is extremely short, the collisions that occur during the translation process will not affect the final flatness).

[0026] (4) The thickness of the diamond film layer is very thin and does not affect the flatness and parallelism of the grinding standard block;

[0027] (5) The diamond film layer in this invention is generated in situ on the substrate material (silicon carbide) of the grinding standard block, with good adhesion and uniform distribution;

[0028] (6) The grinding standard block in this invention is a whole grinding surface that rotates parallel to the inner end face, resulting in more uniform grinding, no heat concentration, and guaranteed flatness and parallelism. Attached Figure Description

[0029] Figure 1 This is a drawing of a part that requires internal end face grinding;

[0030] Figure 2 These are images of a standard grinding block (silicon carbide ring) after sintering. The left side shows the unground state, and the right side shows the ground state (the flatness is 0.0009 after flat crystal inspection).

[0031] Figure 3 These are images of a standard grinding block (silicon carbide ring) after cleaning and coating. The left side shows the cleaning state, and the right side shows the coating state.

[0032] Figure 4 This is a microscopic image of the diamond film coated on a grinding standard block;

[0033] Figure 5 This is a diagram showing the processing status of a double-sided grinder. DETAILED DESCRIPTION

[0034] The application will be further described below in connection with the accompanying drawings and specific examples, but it should not be understood that the scope of the subject matter described herein is limited to the following examples, and any modifications, substitutions and changes made according to the ordinary technical knowledge and common practices in the art without departing from the technical ideas of the application are included in the scope of the application.

[0035] To solve the problem of precision grinding of the inner end face of a part as shown in Figure 1 , the application first prepares a grinding standard block, and the preparation method is as follows:

[0036] ① According to the inner diameter of the part that needs to be ground, an annular silicon carbide ceramic block with an outer diameter slightly smaller than the inner diameter of the part is sintered as a base (if the inner end face is a complete circle, the flat end face of the grinding standard block is also selected as a circle), such as the left drawing in Figure 2 (not ground). For example, a silicon carbide ring with an outer diameter of 212 mm and an inner diameter of 188 mm is sintered at a temperature of 2300-2400°C (the part inner end face in the right drawing in Figure 1 has an outer diameter of 215 mm and an inner diameter of 192 mm), and the density of the silicon carbide ring is ≥115 g / cm 3 .

[0037] ② Put the annular silicon carbide ceramic block into a double-sided grinding machine, use the upper and lower grinding discs with abrasive particles to perform double-sided precision flat grinding, so that the parallelism of the upper and lower flat surfaces of the base is ≤0.01, and the flatness is ≤0.001, such as the right drawing in Figure 2 (already ground and checked by flat crystal, flatness is 0.0009);

[0038] ③ Clean the base before treatment (including oil removal with cleaning agent, drying, etc.);

[0039] ④ Prepare an ultra-thin diamond film on one of the two surfaces of the base after flat grinding, for example, deposit a diamond film with a thickness of 1-5 um on one flat end face of the base by chemical vapor deposition (the thickness of the film is uniform, and does not affect the flatness and parallelism of the base), the macroscopic morphology of the film is shown in the right drawing of Figure 3 , and the microscopic morphology is shown in Figure 4 .

[0040] As shown in Figure 5 , the part that needs to be ground is buckled on the prepared grinding standard block, the inner end face to be ground is in contact with the flat end face of the grinding standard block coated with diamond, and then they are placed together in a double-sided grinding machine, and a flannel pad (i.e. upper and lower grinding discs without abrasive particles) is used for double-sided precision flat grinding.

[0041] The description of the application herein is not intended to be detailed and is well known to those skilled in the art. Although the above describes the specific embodiments of the application in order to facilitate the understanding of the application for those skilled in the art, it should be clear that the application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the application defined and determined by the appended claims, and all the applications using the concept of the application are within the scope of protection.

Claims

1. An inner end face high-precision grinding method, characterized by, The application relates to a standard block for grinding an inner end face of a workpiece. The material density of the standard block is less than that of the workpiece. The parallelism and flatness of the two parallel flat end faces of the standard block are less than those of the inner end face of the workpiece.

2. The inner face high-precision grinding method according to claim 1, characterized by: The surface of the upper and lower grinding plates is a no-grit cloth.

3. The inner face high-precision grinding method according to claim 1, characterized by: The flat end face of the standard block in contact with the inner end face of the workpiece is provided with a diamond coating.

4. The inner face high-precision grinding method according to claim 1, characterized by:

5. A preparation method of the standard block for grinding an inner end face, characterized in that: The material density of the standard block is less than that of the workpiece. The standard block for grinding an inner end face comprises a base body, the maximum outer diameter of the base body is less than the minimum inner diameter of the closed space formed between the inner end face and the outer end face of the workpiece, and the base body comprises two parallel flat end faces. The preparation method comprises the following steps: Step one, selecting the material of the standard block and determining the maximum outer diameter of the standard block according to the minimum inner diameter of the closed space formed between the inner end face and the outer end face of the workpiece; Step two, placing the base body on a double-sided grinding machine and using the upper and lower grinding plates with abrasives to perform double-sided flat grinding on the two parallel flat end faces of the base body; Step three, performing cleaning treatment on the double-sided flat ground base body; Step four, optionally performing diamond coating treatment on one of the two parallel flat end faces of the base body. The base body is ring-shaped.

6. The method of producing an internal face grinding standard block according to claim 5, characterized in that: The base body is made of silicon carbide ceramic material.

7. The method of producing an internal face grinding standard block according to claim 5, characterized in that: In step two, the parallelism and flatness of the two parallel flat end faces after double-sided flat grinding are less than the parallelism and flatness requirements of the inner end face of the workpiece.

8. The method of producing an internal face grinding standard block according to claim 5, characterized in that: ​

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