Metal bond cutting wheel and method of manufacturing the same

Abstract

The application belongs to the technical field of precision cutting tools, and particularly relates to a metal bond cutting grinding wheel and a preparation method thereof. The metal bond cutting grinding wheel comprises a base body and an abrasive layer arranged on the surface of the base body; the abrasive layer is mainly made of main abrasives and a metal bond; the main abrasives are cubic boron nitride, the concentration of the main abrasives in the abrasive layer is 50%-125%, and the granularity of the main abrasives in the abrasive layer is B126-B251. The content of the metal bond and the content of other components in the formula of the grinding wheel are adjusted, so that the cutting performance and the cutting cooling effect of the grinding wheel are improved, and the grinding wheel has good cutting yield and processing efficiency when used for cutting a valve rod of a specific material. When the grinding wheel is used for cutting a valve rod, the valve steel workpiece after cutting has no burr and no burn, and the service life of the grinding wheel can reach 200,000 pieces.

Description

Technical Field

[0001] This invention belongs to the field of precision cutting tool technology, specifically relating to a metal-bonded cutting wheel and its preparation method. Background Technology

[0002] Engine valves are a crucial component of an engine. A valve stem consists of a valve head and a stem, and is divided into intake valves and exhaust valves. The valve head experiences very high temperatures and withstands gas pressure, requiring sufficient strength, rigidity, heat resistance, and wear resistance. Intake valves are typically made of alloy steel (chromium steel, nickel-chromium steel), while exhaust valves are made of heat-resistant alloy (silicon-chromium steel). Alternatively, the exhaust valve head can be made of heat-resistant alloy, and the stem of chromium steel, then welded together. Common one-piece valve stems are typically made of steel-based materials such as 40Cr, 4Cr9Si2, or 4Cr10Si2Mo, which are characterized by high hardness, high strength, and difficulty in machining.

[0003] In existing technology, sintered cubic boron nitride (CBN) cutting wheels are used to cut steel-based materials such as valve stems. Specifically, the main cutting wheels for valve stems on the market are from companies like EHWA (Korea) and Zhongsha. These cutting wheels are characterized by sharp cutting edges, long service life, and high abrasive density, strength, coarse grain size, and high concentration. While these cutting wheels possess many excellent properties, to maintain these characteristics, they are not easily manufactured into ultra-thin cutting wheels.

[0004] In addition, due to the large diameter of such grinding wheels (above 200mm), cold pressing is prone to ring detachment and sintering is also prone to cracking. At the same time, the harsh cutting conditions and high heat generation during the cutting process make it difficult to match the performance of the binder with the grinding wheel matrix, further increasing the difficulty of developing such grinding wheels.

[0005] Chinese patent CN1669708A discloses a diamond / cubic boron nitride saw blade for cutting metal and its manufacturing method. By adjusting the amount and specifications of the metal matrix, matrix, abrasive and other components, and by using processes such as mixing, blending, cold pressing, hot pressing, arc grinding and welding, the processing efficiency and service life of the prepared saw blade are improved. However, this patent does not disclose specific cutting efficiency data.

[0006] In existing technologies, there are few cutting wheels specifically designed for valve stems made of certain materials, and these often fail to balance cutting performance and efficiency. This invention addresses this issue by adjusting the content of metal powder to control the hardness and strength of the binder matrix, thereby designing a special cubic boron nitride (CBN) grinding wheel formulation. Furthermore, a grooved design is incorporated into the grinding wheel structure to enhance cooling and resolve heat generation issues, aiming to achieve a balance between cutting performance and efficiency. Summary of the Invention

[0007] The purpose of this invention is to provide a metal-bonded cutting wheel. By adjusting the content of the metal binder and other components in the wheel formulation, the cutting performance and cutting cooling effect of the wheel are improved, resulting in good cutting yield and processing efficiency when cutting valve stems of specific materials.

[0008] The present invention also provides a method for preparing the metal-bonded cutting wheel.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A metal-bonded cutting wheel, the wheel comprising a matrix and an abrasive layer disposed on the surface of the matrix;

[0011] The abrasive layer is mainly composed of a primary abrasive and a metal binder.

[0012] Specifically, the main abrasive is cubic boron nitride.

[0013] Specifically, the concentration of the main abrasive in the abrasive layer is 50%-125%, preferably 125%.

[0014] Specifically, the particle size of the main abrasive in the abrasive layer is B126-B251, preferably B251, that is, the particle size is 251 micrometers.

[0015] The particle size refers to the screen particle size; in addition, in the field of grinding tools, grinding wheels including abrasives and binders, when the main abrasive is cubic boron nitride, the concentration of cubic boron nitride refers to the ratio of the mass of cubic boron nitride to the volume of the binder.

[0016] Specifically, the metal binder is composed of the following components by mass percentage: 40-60% Cu, 10-20% Sn, 5-15% Ni, 15-25% Fe, and 1-5% WC.

[0017] Specifically, all components of the metal binder are in powder form with a particle size of less than or equal to 170 mesh.

[0018] Specifically, the metal binder is prepared through the following steps:

[0019] The components of the metal binder are mixed according to the specified ratio and stirred for 1-3 hours until fully mixed to obtain the metal binder with a density of 7.0-9.0 g / cm³. 3 .

[0020] Furthermore, the manufacturing process of the metal-bonded cutting wheel includes the following steps:

[0021] 1) Mixing: Add the main abrasive and wetting agent to the prepared metal binder, and mix for 1-3 hours to ensure thorough and uniform mixing, thus obtaining powder material;

[0022] 2) Molding and sintering: The powder material from step 1) is put into the mold, spread, and leveled. Then it is placed on a hot press sintering machine for sintering and molding. The specific sintering process is as follows: at a sintering temperature of 800-850℃ and a sintering pressure of 5-10 MPa, it is kept at the temperature for 1-2 hours. After the heat treatment is completed, it is cooled to room temperature and demolded to obtain the grinding wheel blank.

[0023] 3) Machining: The outer end face and inner hole of the grinding wheel blank in step 2) are machined to finally obtain the grinding wheel.

[0024] Specifically, in step 1), the wetting agent is triglyceride, and the amount added is 0.1-0.2% of the mass of the metal binder. The wetting agent evaporates during the preparation process.

[0025] Furthermore, to improve the bonding ability between the main abrasive cubic boron nitride and the metal binder, this invention also provides a coating process for cubic boron nitride, comprising the following steps:

[0026] (1) Pretreatment cleaning:

[0027] The cubic boron nitride powder is acid-washed in a nitric acid solution with a concentration (mass fraction) of 90-95% for 20-30 seconds, rinsed with distilled water, then alkaline-washed in a NaOH aqueous solution with a mass fraction of 40-50% for 20-30 seconds to remove impurities and oil stains, rinsed with distilled water again, and dried.

[0028] (2) Plating

[0029] Add the dried cubic boron nitride powder from step (1) to a titanium sulfate plating solution with a concentration of 140-150 g / L, stir continuously, and perform plating. The plating temperature is 55-60℃, the plating pH is 3-4, and the time is 10-15 min. The ratio of plating solution to cubic boron nitride is 150-200 g of cubic boron nitride per 1 L of plating solution.

[0030] (3) Cleaning and drying

[0031] The titanium-plated cubic boron nitride powder obtained after plating is washed three times with pure water, and then placed in a vacuum drying oven at 50-55℃ for 10-20 minutes. The titanium-plated cubic boron nitride powder is then sieved and selected using a sieve to obtain the final product.

[0032] Specifically, the coating thickness of the main abrasive, cubic boron nitride, is approximately 56 micrometers.

[0033] Furthermore, in order to ensure good contact between the grinding wheel and the workpiece and improve cutting efficiency, this invention also designs the abrasive layer structure and matrix structure of the metal-bonded cutting grinding wheel, specifically as follows:

[0034] The substrate has a circular cross-section, and the abrasive layer has a circular cross-section that covers the circumference of the circular substrate. The end face of the abrasive layer is corrugated and extends circumferentially along the grinding wheel. The corrugated structure of the end face of the abrasive layer includes crests and troughs.

[0035] Furthermore, the angle between the radial tangent of the wave crest and the circumferential tangent is 30-60°, preferably 60°.

[0036] Furthermore, in the corrugated structure of the abrasive layer end face, the circumferential width of the crest is 4-6 mm, and the width of the gap between two crests is 4-6 mm.

[0037] Furthermore, the present invention also provides the application of the cutting wheel in cutting valve stems.

[0038] Specifically, the valve stem is made of materials such as 40Cr, 4Cr9Si2, 4Cr10Si2Mo, 21-4N, 23-8N, 5Cr8Si2, 4Cr9Si3, 21-2N, 21-12N, 23-8N, etc., preferably 42Cr9Si2.

[0039] Furthermore, the present invention also provides a method for cutting valve stems using the aforementioned cutting abrasive wheel. During cutting, the abrasive wheel rotates at a speed of 2000-3000 r / min, the feed rate is 2-3 mm / s, and the cutting is continuous without dressing. The cutting time for a single valve stem is 8-10 s.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] 1. This invention prepares a metal binder with high hardness and strength by adjusting the composition and dosage of the metal binder, thereby improving the cutting performance and cutting cooling effect of the grinding wheel. When used to cut valve stems of specific materials, it has good cutting yield and processing efficiency.

[0042] 2. This invention designs the head structure of the metal bond cutting wheel by making the abrasive part corrugated. When the wheel rotates at high speed, the coolant can remain in the grooves of the corrugation, which provides better cooling when the wheel and the workpiece come into contact during cutting.

[0043] 3. When using the grinding wheel of the present invention to cut the valve stem, under the condition of cutting line speed of 80m / s and oil cooling, it can achieve the cutting effect of valve steel workpiece without burrs and burns after cutting, and the service life of the grinding wheel can reach 200,000 pieces. Attached Figure Description

[0044] Figure 1 The image shows the scanning electron microscope (SEM) image of metal binder I in the control group in Table 1.

[0045] Figure 2 The image shows a scanning electron microscope (SEM) image of the metal binder in Example 1 of Table 1.

[0046] Figure 3 This is a scanning electron microscope image of the main abrasive after coating;

[0047] Figure 4 This is a scanning electron microscope image of the main abrasive material present in the metal binder after plating;

[0048] Figure 5 This is a cross-sectional view of the abrasive layer;

[0049] Figure 6 for Figure 1 A magnified view of a portion of the image;

[0050] Figure 7 This is a cross-sectional view of the grinding wheel prepared in application experiment 1;

[0051] Figure 8 Photograph of the valve stem workpiece cut for application test 1;

[0052] Figure 9 The image shows the result after cutting in application experiment 1;

[0053] Figure 10 This is a comparison chart of cutting life in application experiment 1. Detailed Implementation

[0054] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0055] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the disclosed technical content. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0056] Example 1

[0057] This invention utilizes a metal bond and an abrasive to prepare a metal bond cutting wheel;

[0058] The grinding wheel includes a base and an abrasive layer disposed on the surface of the base; the base material is carbon steel, that is, an iron-carbon alloy with a carbon content of less than 2.11%, and carbon steel generally contains trace amounts of elements such as silicon, manganese, sulfur, and phosphorus in addition to carbon.

[0059] The abrasive layer is mainly composed of main abrasive and metal binder;

[0060] The main abrasive is cubic boron nitride single-grain abrasive, and the grain size can be adjusted according to different application scenarios.

[0061] The concentration of the main abrasive in the abrasive layer is 50%-125%.

[0062] The particle size of the main abrasive in the abrasive layer is B126-B251.

[0063] The particle size refers to the screen particle size; in addition, in the field of grinding tools, grinding wheels including abrasives and binders, when the main abrasive is cubic boron nitride, the concentration of cubic boron nitride refers to the ratio of the mass of cubic boron nitride to the volume of the binder.

[0064] As those skilled in the art will know, valve stems and other valve components have high hardness and strength, and generate significant heat during cutting. Therefore, the sharpness and lifespan of the grinding wheel used for cutting valve stems are crucial. Thus, it is necessary to select appropriate cubic boron nitride particle size and concentration, while simultaneously requiring a high-strength binder to bond each abrasive grain on the grinding wheel tip, thereby achieving excellent cutting performance.

[0065] Specifically, in this embodiment, the metal binder formulation is designed based on the principle of using density, hardness, and strength as evaluation criteria. The metal binder cutting wheel needs to meet the cutting environment of large depth of cut, therefore the metal binder used to prepare the wheel is required to have high strength and moderate hardness.

[0066] Based on this, Embodiment 1 of the present invention first studies the composition of the metal binder, using copper, tin and additives as the main binders, and conducts experimental analysis to compare the strength and hardness of different formulations, and selects the formulation with suitable strength and hardness.

[0067] Example 1 describes the design of a metal binder formulation, as follows:

[0068] A metal binder comprising the following components by mass percentage: 50% Cu, 15% Sn, 10% Ni, 20% Fe, and 5% WC.

[0069] All components of the metal binder are in powder form with a particle size of less than or equal to 170 mesh.

[0070] During preparation, the components of the metal binder are mixed according to the specified ratio and stirred for 3 hours until fully mixed to obtain the metal binder with a density of 7.0 g / cm³. 3 .

[0071] Meanwhile, this embodiment further adjusted the component ratios of the metal binders and prepared control group metal binder I and control group metal binder II using the above method. Control group metal binder I consists of the following components by mass percentage: 40% Cu, 15% Sn, 20% Ni, 20% Fe, and 5% WC; control group metal binder II consists of the following components by mass percentage: 60% Cu, 15% Sn, 10% Ni, 10% Fe, and 5% WC.

[0072] The mechanical properties of the prepared metal binders were tested, and the results are as follows:

[0073] Table 1 Mechanical properties of metal binders

[0074]

[0075]

[0076] As can be seen from Table 1, the metal binder prepared in Example 1 has good properties such as hardness and flexural strength.

[0077] The bonding force of the binder on the abrasive and the self-sharpening property of the grinding wheel together determine the cutting power of the abrasive. If the binder is too hard, it tightly holds the abrasive, causing the outer abrasive to wear down and become less sharp but not completely detached, preventing new abrasive from being exposed, thus dulling the grinding wheel. Conversely, if the binder cannot withstand the impact of external forces during cutting and easily detaches, the abrasive will not perform its cutting function, greatly reducing the life of the grinding wheel and the cutting efficiency. The binder in this invention has a certain holding force on the abrasive and will detach under certain conditions, allowing new abrasive to emerge.

[0078] Figure 1 The image in the middle is a scanning electron microscope image of the control group metal binder I in Table 1. Figure 1 As can be seen, its surface is smooth, its holding force is weak, and when it combines with abrasive, the abrasive is easy to fall off.

[0079] Figure 2 The image shown in Table 1 is a scanning electron microscope (SEM) image of the metal binder in Example 1. Figure 2 As can be seen, it has a certain roughness, high holding force, and when combined with abrasive, the abrasive comet phenomenon is obvious, making it easy to combine with abrasive.

[0080] Example 2

[0081] The grit size and concentration of the abrasive have a significant impact on the cutting efficiency and quality of the grinding wheel. Larger grit results in a wider impact area and sharper cuts, but produces a rougher workpiece; finer grit produces a smoother cut but lower cutting efficiency; higher concentration results in a longer lifespan but poorer cutting quality; and lower concentration results in better cutting quality but a shorter lifespan. Therefore, the grit size and concentration of cubic boron nitride used to minimize chipping and maximize cutting efficiency must be selected based on the hardness and strength of the material being processed.

[0082] Therefore, in Example 2, based on Example 1, a valve stem metal bond cutting wheel with specifications of M 1A1R 200×1.0×40×0.8×5 was prepared. The performance of the prepared wheel was tested by cutting, and cubic boron nitride was screened.

[0083] During the screening process, the metal binder formulation and grinding wheel formulation from Example 1 were used, and cubic boron nitride with different concentrations and particle sizes was selected to prepare metal binder cutting grinding wheels.

[0084] The manufacturing process of the grinding wheel is as follows:

[0085] 1) Mixing: Add the main abrasive and wetting agent (the wetting agent is triglyceride, and the amount added is 0.1% of the mass of the metal binder) to the metal binder prepared in Example 1, and mix for 3 hours to make it fully mixed and uniform, so as to obtain powder material;

[0086] 2) Molding and sintering: The powder material from step 1) is put into the mold, spread, and leveled. Then it is placed on a hot press sintering machine for sintering and molding. The specific sintering process is as follows: at a sintering temperature of 800℃ and a sintering pressure of 10Mpa, it is kept at the temperature for 2 hours. After the heat preservation is completed, it is cooled to room temperature and demolded to obtain the grinding wheel blank.

[0087] 3) Machining: The outer end face and inner hole of the grinding wheel blank in step 2) are machined. The inner hole is machined to the tolerance of the mechanical industry H7 standard, and the outer end face is ground round.

[0088] 4) Appearance treatment: After machining, the appearance is beautified, rust prevention is carried out and other post-treatments are performed to finally obtain the grinding wheel.

[0089] The following section describes the screening of cubic boron nitride concentration and particle size by testing the cutting performance of the prepared grinding wheel.

[0090] The object being cut is the valve stem, which is typically made of steel base materials such as 40Cr, 4Cr9Si2, 4Cr10Si2Mo, 21-4N, 23-8N, 5Cr8Si2, 4Cr9Si3, 21-2N, 21-12N, and 23-8N. In this embodiment, the valve stem workpiece is made of 42Cr9Si2; the workpiece hardness is 25-38HRC, and the diameter is φ5-φ12mm.

[0091] During cutting, the grinding wheel is mounted on the machine, and high-efficiency, batch cutting is achieved by setting the grinding wheel speed, guide wheel speed, and single feed rate with specific cutting process parameters.

[0092] The specific cutting parameters are: grinding wheel speed 3000 r / min, feed rate 3 mm / s, continuous cutting, no dressing. The cutting time for a single valve stem is approximately 10 seconds.

[0093] By comparing the sharpness of the grinding wheel in the cutting test, the particle size and concentration of cubic boron nitride were screened. The sharpness was characterized by the maximum cutting torque displayed by the cutting machine. The larger the torque, the smaller the sharpness. The specific test results are shown in Table 2.

[0094] Table 2 Cutting torque under different particle sizes and concentrations of CBN

[0095]

[0096] As shown in Table 2, as the particle size of cubic boron nitride abrasive decreases, the cutting machine exhibits increased torque and decreased sharpness. This is because the exposure or protrusion height of the cubic boron nitride on the cutting surface affects the cutting depth of each particle, thus influencing the material removal rate of the cutting tool. Using larger cubic boron nitride particles with higher exposure will result in a faster material removal rate.

[0097] In addition, the effect of concentration on cutting performance was compared: as the concentration increased, the cutting torque of the three types of cubic boron nitride cutting wheels first increased and then decreased. This is mainly because as the concentration increases, more cubic boron nitride participates in the cutting, increasing the cumulative destructive effect of the cubic boron nitride on the workpiece and improving sharpness. Due to the high hardness of valve steel, it is highly destructive to the cutting wheel, requiring a long wheel life; therefore, a high concentration is chosen.

[0098] By studying the effects of cubic boron nitride concentration and particle size on the mechanical properties of grinding wheels, as well as their influence on cutting efficiency, workpiece cutting quality, and lifespan, this invention selects cubic boron nitride with an abrasive concentration of 125% and a screen particle size of 50 / 60 as the main abrasive. That is, the particle size of cubic boron nitride is 251 micrometers (B251), which has a high degree of bonding with the metal binder in the grinding wheel, resulting in better sharpness and lifespan.

[0099] Example 3

[0100] Cubic boron nitride is synthesized from hexagonal boron nitride and a catalyst under high temperature and pressure. It is a new type of product that emerged after the advent of synthetic diamond. It possesses excellent properties such as high hardness, thermal stability, chemical inertness, good infrared transmittance, and a wide bandgap. Its hardness is second only to diamond, but its thermal stability is far superior. It also exhibits significant chemical stability towards ferrous metals. Therefore, it is used as an abrasive for processing products containing ferrous metals.

[0101] To enhance its bonding ability with the metal binder, the present invention also performs a coating treatment on cubic boron nitride. A titanium layer is coated on the surface of the abrasive using a chemical plating method. This not only increases the chemical bonding force between titanium and copper-tin alloy, but also roughens the surface, increases the specific surface area, and enhances the binder's ability to hold it.

[0102] Example 3 uses cubic boron nitride with a concentration of 125% and a particle size of 50 / 60, which was screened in Example 2, for coating treatment.

[0103] The specific plating process is as follows:

[0104] (1) Pretreatment cleaning:

[0105] Cubic boron nitride powder (particle size B251) was acid-washed in a 95% nitric acid solution for 30 seconds, rinsed with distilled water, then alkaline-washed in a 50% NaOH aqueous solution for 30 seconds to remove impurities and oil, rinsed with distilled water again, and dried.

[0106] (2) Plating

[0107] Add the dried cubic boron nitride powder from step (1) to a titanium sulfate plating solution with a concentration of 150 g / L, stir continuously, and perform plating. The plating temperature is 60°C, the plating pH is 3, and the time is 10 min. The ratio of plating solution to cubic boron nitride is 200 g of cubic boron nitride per 1 L of plating solution.

[0108] (3) Cleaning and drying

[0109] The titanium-plated cubic boron nitride powder obtained after plating is washed three times with pure water, and then dried in a vacuum drying oven at 50°C for 20 minutes. The titanium-plated cubic boron nitride powder is then sieved and selected using a sieve to obtain the final product.

[0110] Scanning electron microscope image of the master abrasive after coating is shown below. Figure 3 As shown, the coating thickness is approximately 56 micrometers. In Example 3, cubic boron nitride coated with titanium was used as the main abrasive. The grinding wheel was prepared using the metal binder formulation and grinding wheel formulation from Example 1, as well as the preparation method from Example 2. The scanning electron microscope image of the main abrasive in the metal binder is shown below. Figure 4 As shown in Table 3, the performance of the prepared grinding wheel was tested. Figure 4 As can be seen from Table 3, the prepared grinding wheel has good mechanical properties.

[0111] Table 3

[0112]

[0113] Example 4

[0114] Large-diameter metal-bonded cutting wheels are mainly used for cutting with large depths of cut. Due to the large contact area between the wheel and the workpiece, the grinding force is large, the grinding temperature is high, chip removal is difficult, and coolant is not easy to reach, resulting in a relatively harsh cutting environment.

[0115] Based on this, Example 4, building upon Examples 1, 2, and 3, designs the abrasive layer structure and matrix structure of the metal-bonded cutting wheel head, specifically as follows:

[0116] The metal-bonded cutting wheel includes a substrate and an abrasive layer disposed on the surface of the substrate. The substrate has a circular cross-section, and the abrasive layer has a ring-shaped cross-section covering the circumference of the circular substrate. Simultaneously, the end face of the abrasive layer is corrugated, extending circumferentially along the grinding wheel. The corrugated structure of the end face of the abrasive layer includes crests and troughs, such as... Figure 5 , 6 As shown, Figure 5 This is a cross-sectional view of the abrasive layer. Figure 6 for Figure 5 A magnified view of a portion of the image. Figure 5 , 6 The intervals filled with diagonal lines represent the cross-sections of wave crests, while the blank intervals represent the cross-sections at the intervals between two wave crests. Figure 6 As can be seen, the angle α between the radial tangent of the wave crest and the circumferential tangent is 60°. Meanwhile, in the corrugated structure of the abrasive layer end face, the circumferential width L1 of the wave crest is 6mm, the width L2 between two wave crests is 4mm, and the radial width of the abrasive layer is 5-10mm.

[0117] In this embodiment, a corrugated structure extending along the circumference of the grinding wheel is designed on the end face of the abrasive layer, thereby forming a crest structure and a trough structure on the end face of the abrasive layer. The gap between the two crests serves as a groove, where coolant can be stored in the corrugated groove when the grinding wheel rotates at high speed, forming a water tank structure for storing coolant. When the grinding wheel reaches the cutting area, it makes cutting contact with the workpiece, resulting in better cooling.

[0118] Application Experiment 1

[0119] Using the metal bond formulation, grinding wheel formulation, and preparation method described in Examples 1 and 2, as well as the plating process of Example 3 and the abrasive layer structure of Example 4, a valve stem metal bond cutting grinding wheel, model 1A1R, with the following specifications: outer diameter D (250-300mm), thickness T (1.0-2.0mm), and inner hole H-h7, is prepared. The grinding wheel structure is as follows: Figure 7 As shown.

[0120] (a) Valve stem cutting test was conducted using the prepared grinding wheel. The specific cutting parameters were: grinding wheel speed 3000 r / min, feed rate 3 mm / s, continuous cutting, no dressing. The cutting time for a single valve stem was approximately 10 s.

[0121] The valve stem workpiece is made of 42Cr9Si2 material; its hardness is 25-38HRC, and its diameter is [missing information]. The valve stem workpieces that were cut are as follows Figure 8 As shown.

[0122] The cutting linear speed is 80m / s, and oil cooling is used for head cutting of valve stem workpieces to ensure dimensional accuracy. The products are burr-free, burn-free, and have a service life of up to 200,000 pieces. The post-cutting effect is as follows: Figure 9 As shown.

[0123] Figure 9 The part numbered 1 is the result of cutting with the grinding wheel of the present invention; Figure 9 The cutting results of the grinding wheels labeled 2 and 3 are for comparison (grind wheel 2 is a Korean EWHA base type grinding wheel, and grinding wheel 3 is a Japanese ASAHI base type grinding wheel). It can be seen that grinding wheel 2 has burr phenomenon when cutting, while grinding wheel 3 has burn phenomenon when cutting.

[0124] (ii) A comparative test of valve stem cutting life was conducted using the prepared grinding wheel.

[0125] The specific cutting parameters and objects are the same as those in Part (I) above. The cutting life results are as follows: Figure 10 As shown, the left bar chart represents the cutting life test results of the Korean EWHA matrix grinding wheel, the right bar chart represents the cutting life test results of the Japanese ASAHI matrix grinding wheel, and the middle bar chart represents the cutting life test results of the grinding wheel prepared by application test 1 in this application.

[0126] from Figure 10 As can be seen from the data, the grinding wheel of the present invention has a lifespan of 220,000 pieces, while the lifespans of other comparative grinding wheels are 140,000 pieces and 180,000 pieces, respectively, which are 36% and 18% lower than that of the grinding wheel of the present invention.

[0127] The above embodiments are illustrative examples of the implementation of the present invention. The implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A metal-bonded cutting wheel, characterized in that, The grinding wheel includes a base and an abrasive layer disposed on the surface of the base; the abrasive layer is mainly made of a main abrasive and a metal binder; the main abrasive is cubic boron nitride; The concentration of the main abrasive in the abrasive layer is 50%-125%; The particle size of the main abrasive in the abrasive layer is B126-B251; The metal binder is composed of the following components by mass percentage: 40-60% Cu, 10-20% Sn, 5-15% Ni, 15-25% Fe, and 1-5% WC. All components of the metal binder are in powder form with a particle size of less than or equal to 170 mesh; The metal-bonded cutting wheel is prepared by the following steps: 1) Mixing: Add the main abrasive and wetting agent to the prepared metal binder, and mix for 1-3 hours until fully mixed and homogeneous to obtain powder material; 2) Molding and sintering: The powder material from step 1) is put into the mold, spread, scraped, and then sintered. The sintering process is as follows: at a sintering temperature of 800-850℃ and a sintering pressure of 5-10Mpa, the material is kept at the temperature for 1-2 hours. After the temperature is kept at the temperature, the material is cooled to room temperature and demolded to obtain the grinding wheel blank. 3) Machining: The outer end face and inner hole of the grinding wheel blank in step 2) are machined to finally obtain the grinding wheel; In step 1), the wetting agent is triglyceride, and the amount added is 0.1-0.2% of the mass of the metal binder. The wetting agent evaporates during the preparation process. During the preparation of the metal-bonded cutting wheel, cubic boron nitride is also plated. The cubic boron nitride plating process includes the following steps: (1) Pre-treatment cleaning: The cubic boron nitride powder is acid-washed in a 90-95% nitric acid solution for 20-30 seconds, rinsed with distilled water, then alkaline-washed in a 40-50% NaOH aqueous solution for 20-30 seconds to remove impurities and oil, rinsed with distilled water again, and dried. (2) Plating Add the dried cubic boron nitride powder from step (1) to a titanium sulfate plating solution with a concentration of 140-150 g / L, stir continuously, and perform plating. The plating temperature is 55-60℃, the plating pH is 3-4, and the time is 10-15 min. The ratio of plating solution to cubic boron nitride is 150-200 g of cubic boron nitride per 1 L of plating solution. (3) Cleaning and drying The titanium-plated cubic boron nitride powder obtained after plating is washed three times with pure water, and then placed in a vacuum drying oven at 50-55℃ for 10-20 minutes. The titanium-plated cubic boron nitride powder is then sieved and selected using a sieve to obtain the final product. The substrate has a circular cross-section, and the abrasive layer has a circular cross-section that covers the circumference of the circular substrate. The end face of the abrasive layer is corrugated and extends circumferentially along the grinding wheel. The corrugated structure of the end face of the abrasive layer includes crests and troughs.

2. The metal-bonded cutting wheel as described in claim 1, characterized in that, The metal binder is prepared by the following steps: The components of the metal binder are mixed according to the specified ratio and stirred for 1-3 hours until fully mixed to obtain the metal binder with a density of 7.0-9.0 g / cm³. 3 .

3. The metal-bonded cutting wheel as described in claim 1, characterized in that, The angle between the radial tangent of the wave crest and the circumferential tangent is 30-60°.

4. The metal-bonded cutting wheel as described in claim 1, characterized in that, In the corrugated structure of the abrasive layer end face, the circumferential width of the crest is 4-6 mm, and the width of the gap between two crests is 4-6 mm.

5. The application of the metal-bonded cutting wheel according to any one of claims 1-4 in cutting valve stems, characterized in that, The valve stem is made of 42Cr9Si2 material.

6. A method for cutting valve stems using a metal-bonded cutting wheel according to any one of claims 1-4, characterized in that, The valve stem is made of 42Cr9Si2 material. During cutting, the grinding wheel speed is 2000-3000 r / min, the feed speed is 2-3 mm / s, and the cutting time for a single valve stem is 8-10 s.

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