Axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at heat input end and preparation method thereof

Abstract

The present invention relates to an axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end and a preparation method thereof, wherein the grinding wheel mainly comprises a base, a cover plate, a tool rod, a working medium, an abrasive layer, and a gradient foam metal. The base is manufactured by optimizing the design by combining a lattice structure and 3D printing technology, and a gradient foam metal is embedded in the oscillating heat pipe flow channel position corresponding to the heat input end. The pore size and porosity of the gradient foam metal gradually increase from the flow channel wall to the flow channel center, and the hydrophilicity gradually decreases, forming a hollow trumpet-shaped structure in which the material thickness gradually increases vertically downward along the axis of the grinding wheel. During the grinding process, the gradient foam metal in the grinding wheel increases the density of the vaporization core in the flow channel due to the porous structure characteristics, accelerates the separation of bubbles in the nucleate boiling process, promotes phase change heat transfer in the tube, and effectively avoids the occurrence of local dry-out phenomenon. The grinding wheel structure can significantly improve the heat conduction capacity and working stability.

Description

Technical Field

[0001] The present invention relates to an axially oscillating heat pipe grinding wheel reinforced with a gradient foam metal at the heat input end and a method for preparing the same. The grinding wheel is suitable for the field of grinding processing. By embedding a gradient foam metal at the heat input end of the oscillating heat pipe flow channel in the grinding wheel, the phase change heat transfer of the working medium inside the grinding wheel during the grinding process is significantly enhanced, and the occurrence of local burn-out is also effectively avoided. As the heat transfer performance of the grinding wheel itself is improved, more grinding heat energy is diverted to the grinding arc area through the grinding wheel, thereby reducing the accumulation of heat in the grinding arc area, effectively lowering the grinding temperature, and avoiding thermal damage to the workpiece surface. Background Art

[0002] When grinding difficult-to-machine materials, a large amount of heat is generated in the grinding arc zone. This heat easily accumulates in the grinding arc zone (the contact area between the workpiece and the grinding wheel), resulting in excessively high grinding temperatures, which affects machining quality and efficiency. Oscillating heat pipes, as components with extremely high heat transfer coefficients, are integrated with the grinding wheel substrate. The circulating motion and phase change of the working fluid within the oscillating heat pipes continuously and efficiently remove heat from the grinding arc zone, enhancing heat transfer, preventing grinding burns, and improving grinding efficiency.

[0003] Studies have disclosed methods for making combined and integral axial heat pipe grinding wheels. For example, the invention patent with publication number CN109623675B discloses a combined axial rotating pulsating heat pipe grinding wheel and its preparation method, and the invention patent with publication number CN111283561B discloses an integral axial rotating oscillating heat pipe grinding wheel and its preparation method. Both patents provide specific steps for making axial oscillating heat pipe grinding wheels, and the structure is simple, reliable, and the production cost is low. In these two invention patents, the oscillating heat pipe provides conditions for achieving efficient heat exchange of the grinding wheel with its self-excited bubble-liquid plug oscillating flow two-phase motion form and the heat transfer form based on sensible heat transfer. However, during the heat transfer process, the smooth surface of the flow channel wall reduces the number of bubble nucleation points, resulting in a prolonged start-up time of the oscillating heat pipe grinding wheel.

[0004] Related research has provided methods for preparing gradient metal foams. In their paper, "Experimental Investigation on Boiling Heat Transfer Enhanced by Gradient Aperture Porous Copper," published in Applied Thermal Engineering, 191(2021): 116877, Yahui Ma et al. fabricated multilayered, gradient-aperture porous copper foams using a pressing, vacuum sintering, and cleaning process. They experimentally investigated the pool boiling curves and corresponding bubble dynamics of these copper foam samples. The results showed that the gradient aperture structure facilitated steam escape and liquid replenishment, significantly enhancing boiling heat transfer.

[0005] There are related studies that apply traditional foam metals of the same pore size to single-layer super-hard abrasive grinding wheels. The invention patent with publication number CN109571292B discloses a new type of high thermal conductivity phase change heat storage super-hard abrasive grinding wheel and its preparation method, including a grinding wheel base with an annular tube cavity, the interior of the annular tube cavity is filled with traditional foam metal, and is filled with an appropriate amount of heat transfer medium. The grinding wheel is designed to accelerate the boiling of the medium and the transfer of the grinding heat introduced into the grinding wheel to the inner end of the base by taking advantage of the large specific surface area and good permeability of the foam metal. However, the above patent does not take into account that the high density of the foam metal affects the reflux of the medium, which can easily lead to drying up at the heated wall surface, thereby affecting the overall heat transfer performance of the grinding wheel and worsening it.

[0006] Based on the above problems, it can be found that the performance of the axial oscillating heat pipe grinding wheel still needs to be optimized to improve its heat conduction ability and working stability. Summary of the Invention

[0007] Purpose of the Invention: To address the shortcomings of the prior art, the present invention provides an axially oscillating heat pipe grinding wheel reinforced with a gradient metal foam at the heat input end and a method for preparing the same. The core concept is to embed a gradient metal foam at the heat input end of the oscillating heat pipe flow channel in the grinding wheel. The gradient metal foam gradually increases in pore size and porosity from the flow channel wall to the flow channel center, while its hydrophilicity gradually decreases, forming a hollow trumpet-shaped structure with gradually increasing material thickness vertically downward along the grinding wheel axis. During the grinding process, the porous structure of the gradient metal foam in the grinding wheel increases the density of the vaporization core within the flow channel, accelerates the detachment of bubbles during nucleate boiling, promotes phase change heat transfer within the tube, and effectively avoids the occurrence of localized burnout. Furthermore, the grinding wheel base is optimized and manufactured using a lattice structure combined with 3D printing technology. This results in superior mechanical and thermal properties of the grinding wheel as a whole, while also achieving overall lightweighting and reducing power consumption. The grinding wheel structure described in the present invention can significantly improve the heat conduction capacity and operating stability of traditional oscillating heat pipe grinding wheels in high-efficiency grinding processes, thereby expanding the operating range of axially oscillating heat pipe grinding wheels.

[0008] Technical Solution: To achieve the aforementioned objectives, the present invention provides an axially oscillating heat pipe grinding wheel reinforced with gradient metal foam at the heat input end. The wheel comprises a base, a cover plate, a tool bar, a working medium, an abrasive layer, and a gradient metal foam. Its grinding motion is rotational about its axis.

[0009] This patent describes an axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end. The base body of the grinding wheel is processed with multi-circuit oscillating heat pipe channels, gradient foam metal is embedded at the heat input end of the channels, the multi-circuit channels are sealed with a cover plate, and a single layer of super-hard abrasive is electroplated or brazed on the working surface of the base body. The vacuum injection system is connected to the vacuum injection pipe on the grinding wheel base body to complete the injection work, and then the pipe is sealed to ensure that the grinding wheel as a whole has good airtightness. One end of the tool bar is connected to the cover plate in an assembled manner, and the other end is connected to the machine tool spindle to drive the grinding wheel to rotate around its own axis.

[0010] Based on the above, all parts of the oscillating heat pipe grinding wheel are made of steel materials with high thermal conductivity and good structural strength (such as carbon steel, stainless steel, etc.);

[0011] Based on the above, the central area of ​​the grinding wheel base adopts a lattice structure optimization design, which not only achieves lightweight, but also significantly improves its mechanical and thermal properties;

[0012] Based on the above, the grinding wheel substrate with multi-circuit flow channels is processed by 3D printing technology. The 3D printing technologies that can be used include: laser powder bed fusion technology, laser directed energy deposition technology, etc.

[0013] Based on the above, the gradient foam metal can be made of materials such as foam copper, foam steel, and foam nickel, with a pore size gradient varying between 30ppi and 30,000ppi, a porosity gradient varying between 75% and 98%, and a through-porosity ≥ 90%;

[0014] Based on the above, two gradient foam metals are embedded in each circuit channel, and the outer circular surface of the gradient foam metal is tightly fitted with the channel wall;

[0015] Based on the above, the gradient foam metal has dual characteristics: first, the pore size increases from the submicron level to the submillimeter level from the oscillating heat pipe wall to the center, and the porosity also increases; second, it is highly hydrophilic near the wall surface and highly hydrophobic in the central area. In addition, the foam metal is hollow trumpet-shaped, and the wall thickness gradually increases toward the bottom end of the grinding wheel; the gradient foam metal is embedded at the heat input end of the flow channel, which changes the contact environment between the working fluid and the flow channel wall. The micro-void structure and large specific surface area of ​​the foam metal provide a large number of vaporization cores for the nucleation boiling of the working fluid, which promotes the occurrence of phase change heat transfer. Therefore, the new grinding wheel has significant advantages in enhancing heat exchange in the grinding arc zone.

[0016] Based on the above, the connection between the cover plate and the grinding wheel base can be achieved by various welding methods, such as laser welding, argon arc welding, etc.

[0017] Based on the above, the working fluid can be water, methanol, acetone, etc., which can be determined according to the actual grinding conditions;

[0018] Based on the above, the super-hard abrasive can be diamond or CBN, and the abrasive can be arranged in a disordered arrangement or an ordered arrangement on the working surface of the grinding wheel.

[0019] The present invention relates to an axial oscillating heat pipe grinding wheel with a gradient foam metal reinforcement at the heat input end. The specific manufacturing steps are as follows:

[0020] Step 1: Based on the actual grinding process requirements, the lattice structure and 3D printing technology are used to optimize the design and process the oscillating heat pipe grinding wheel base. The grinding wheel base is a hollow cylinder with a honeycomb structure in the middle area. The grinding wheel base is equipped with a multi-loop oscillating heat pipe flow channel, a vacuum injection pipe at the heat input end, and one or more heat dissipation fins at the heat output end.

[0021] Step 2: Process the gradient metal foam, which is hollow and trumpet-shaped as a whole, with increasing wall thickness towards the bottom. From the wall to the center of the oscillating heat pipe flow channel, the pore size gradually increases from submicron to submillimeter, and the porosity also gradually increases. Then, apply a layer of structural silver glue with high thermal conductivity to its outer surface and embed it into the multi-circuit flow channel at the heat input end of the oscillating heat pipe grinding wheel, so that its bottom is flush with the bottom of the direct flow channel. Then, heat and dry the grinding wheel base to ensure that the gradient metal foam fits tightly to the wall of the oscillating heat pipe flow channel.

[0022] Step 3: Weld the cover plate to the grinding wheel base to form an integrated structure. After welding, perform a leak test to ensure good airtightness. Then, use electroplating or brazing technology to plate or weld superhard abrasives with high thermal conductivity on the working surface of the grinding wheel base. Superhard abrasives include diamond or CBN.

[0023] Step 4: Build a vacuum injection system that matches the oscillating heat pipe flow channel in the grinding wheel base, connect the system to the vacuum injection pipeline on the base, first evacuate the multi-circuit pipeline to a low vacuum degree, and then inject the heat transfer medium suitable for the grinding working conditions into the flow channel. The injection amount of the medium must also be adapted. After the injection is completed, perform the tail sealing work;

[0024] Step 5: Connect one end of the tool bar to the cover plate with bolts, and the other end to the machine tool spindle, thereby driving the grinding wheel to rotate around its own axis.

[0025] Beneficial effects:

[0026] (1) The axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end proposed in the present invention not only significantly promotes phase change heat transfer in the pipe, but also effectively avoids the occurrence of local dry-out phenomenon, broadens the working range of the axial oscillating heat pipe grinding wheel, and improves its working stability by embedding gradient foam metal at the position of the oscillating heat pipe flow channel corresponding to the heat input end.

[0027] (2) The grinding wheel base is designed and manufactured by combining lattice structure and 3D printing technology, so the overall mechanical and thermal properties of the grinding wheel will become better, and it can also be lightweight and reduce energy consumption.

[0028] (3) The gradient metal foam embedded in the oscillating heat pipe flow channel gradually increases in pore size and porosity from the flow channel wall to the flow channel center, while its hydrophilicity gradually decreases, forming a hollow trumpet-shaped structure with gradually increasing material thickness vertically downward along the grinding wheel axis. The high density of the metal foam in the annular tube cavity hinders the backflow of the gas working medium after liquefaction, while the hollow trumpet-shaped structure does not have to worry about the backflow problem at all. In addition, the closer to the wall, the stronger the hydrophilicity of the metal foam, which can further enhance the boiling heat transfer, while the closer to the center of the flow channel, the stronger its hydrophobicity, which can further promote the flow of bubbles, so that the grinding wheel can still maintain good heat transfer performance under high centrifugal acceleration, increasing working stability.

[0029] (4) The pore size of the filled foam metal has a gradient change structure. The gradient change structure of the foam metal can promote the accelerated bubbles to smoothly escape from it, which effectively prevents the accumulation of bubbles, avoids the increase of thermal resistance and the occurrence of local burning.

[0030] In summary, the present invention embeds gradient foam metal at the heat input end of the oscillating heat pipe flow channel in the grinding wheel, which not only significantly enhances the phase change heat transfer of the working medium inside the grinding wheel during the grinding process, but also effectively avoids the occurrence of local burning-out phenomenon, broadens the working range of the axial oscillating heat pipe grinding wheel, and improves its working stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is an exploded view of the structure of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0032] Figure 2 This is a schematic diagram of the upper structure of the 3D-printed base of the axially oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0033] Figure 3 This is a schematic diagram of the lower structure of the 3D-printed base of the axially oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0034] Figure 4 This is a schematic diagram of the connection between the six-circuit flow channel and the gradient foam metal of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0035] Figure 5 Schematic diagram of the gradient foam metal of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0036] Figure 6 A schematic cross-sectional view and a partially enlarged schematic view of the gradient foam metal of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0037] Figure 7 This is a schematic diagram of the hydrophilicity from outside to inside of the gradient foam metal of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0038] Figure 8 This is a schematic diagram of the cover plate of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention;

[0039] Figure 9 Schematic diagram of the welding of the cover plate and base of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention and a schematic diagram of the electroplated orderly arranged abrasives;

[0040] Figure 10 Schematic diagram of the tool bar of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end according to the present invention;

[0041] Figure 11 This is a schematic diagram of the simulation of the heat exchange effect of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end and the non-axial oscillating heat pipe grinding wheel on the workpiece.

[0042] Description of the main reference numerals in the figures:

[0043] 1 substrate, 1-1 six-loop oscillating heat pipe flow channel, 1-1-1 direct current flow channel, 1-1-2 connecting flow channel, 1-2 heat dissipation fins, 1-3 vacuum injection pipeline, 1-4 honeycomb structure formed by lattice structure optimization.

[0044] 2 Gradient metal foam.

[0045] 3 Cover plate, 3-1 cover plate threaded hole.

[0046] 4 Abrasive layer.

[0047] 5 tool shank, 5-1 tool shank countersunk hole.

[0048] 6 M3×6 bolts. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the technical solutions in the present invention's patent application, the technical solutions in this application are clearly and completely described below in conjunction with the drawings in this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application.

[0050] Figure 1 This is an exploded view of the structure of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention. Figure 1 The present invention provides an axial oscillating heat pipe grinding wheel with a gradient foam metal reinforced at the heat input end, which mainly includes a base 1 made of 45 steel, a gradient foam metal 2, a cover plate 3, a tool rod 5 and other related accessories and structures.

[0051] Figure 2 This is a schematic diagram of the upper structure of the 3D-printed base of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention. Figure 3 This is a schematic diagram of the lower structure of the 3D printed base of the axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end of the present invention. Figure 2 、 3 As shown, the 45 steel substrate was optimized and manufactured using a lattice structure and 3D printing technology. The substrate (excluding heat sink fins 1-2) is 59 mm tall and 50 mm in diameter. Inside, there are six oscillating heat pipe channels 1-1. These channels include 12 direct current channels 1-1-1 and 12 connecting channels 1-1-2. The direct current channels have a diameter of 3 mm, and the connecting channels are both 3 mm wide and deep. There are six heat sink fins 1-2 located at the heat output end (the heat input end of the grinding wheel is located in the contact area between the grinding wheel and the workpiece). The top fin is 2 mm thick, while the remaining fins are 1 mm thick. Each fin has a diameter of 60 mm, and the spacing between fins is 1 mm. A groove with a diameter of 50 mm and a thickness of 1 mm is located between the heat sink fins and the substrate. The grinding wheel base is a hollow cylinder with a wall thickness of 4 mm. The center region contains honeycomb structures 1-4, optimized using a lattice structure. This enhances the overall mechanical and thermal properties of the grinding wheel while also achieving lightweight and reducing energy consumption. The honeycomb structure is designed using a hexagonal lattice with a diameter of 42 mm and a height of 55 mm, with the bottom surface flush with the base of the base.

[0052] The gradient foam metal 2 is placed in the direct current flow channel 1-1-1, as shown in FIG. Figure 4 As shown. The gradient metal foam 2 is hollow and trumpet-shaped as a whole, with the wall thickness increasing towards the bottom. In this example, the gradient metal foam has a height of 17.5 mm, an outer diameter of 3 mm, and a minimum inner diameter of 1 mm. It has dual characteristics: on the one hand, from the wall to the center of the oscillating heat pipe flow channel, the pore size gradually increases from submicron to submillimeter, and at the same time, the porosity also gradually increases, as shown in Figure 2. Figure 6 On the other hand, the closer to the wall, the stronger the hydrophilicity of the foam metal, and the closer to the center of the flow channel, the stronger its hydrophobicity, as shown in Figure 7As shown. The gradient metal foam was made of copper foam (made through a pressing, vacuum sintering, and cleaning process; see "Experimental investigation on boiling heat transfer enhanced by gradient aperture porous copper" in Applied Thermal Engineering, 191(2021): 116877). The pore size gradually increased from 30,000 ppi to 30 ppi, the porosity gradually increased from 90% to 98%, and the through-hole ratio was 98%. After the 12 gradient metal foams were processed, a layer of conductive silver paste with high thermal conductivity (Henkel Loctite 84-1LMISR4 conductive silver paste) was evenly applied to their outer surfaces. They were then manually embedded into the 12 DC channels, with the bottom of the gradient metal foam aligned with the bottom of the DC channel. Finally, the grinding wheel substrate was placed in an oven and heated at 175°C for 60 minutes to cure the silver paste and ensure a close fit between the gradient metal foam and the flow channel wall to reduce thermal resistance.

[0053] like Figure 9 As shown, a cover plate 3 is used to seal the oscillating heat pipe flow channel embedded in the gradient foam metal. The cover plate is a stepped shaft style, with an upper cylindrical diameter of 50 mm and a thickness of 1 mm, a lower cylindrical diameter of 42 mm and a thickness of 4 mm, and four evenly distributed M3×0.5 threaded holes 3-1, as shown in FIG. Figure 8 As shown in the figure, after the cover plate covers the base, the upper surface is flush with the upper surface of the base. The two are then welded into a single structure using laser welding at a power of 1200 W and a welding speed of 2500 mm / min. The welded base is then leak-tested to ensure good airtightness. If any leaks are detected, repair welding is required.

[0054] On the working surface of the oscillating heat pipe grinding wheel, CBN abrasive grains with a particle size of 80 / 100# are plated using an electroplating process. The abrasives are arranged in an orderly manner to form an abrasive layer 4, such as Figure 9 As shown in the figure, the orderly arrangement of abrasives not only helps to reduce grinding heat, but also provides sufficient chip space, effectively reducing the occurrence of grinding wheel clogging.

[0055] Acetone is injected into the six-circuit flow path of the oscillating heat pipe via a vacuum injection system and vacuum injection lines 1-3, achieving a fill rate (the ratio of injected fluid volume to the internal volume of the oscillating heat pipe) of 60%. Acetone was chosen as the heat transfer fluid due to its low boiling point, low surface tension, and dynamic viscosity. These properties significantly reduce the resistance required to overcome during the bubble-liquid plug oscillation process, facilitating fluid circulation and significantly improving heat transfer performance. After injection, the vacuum injection lines are sealed using an ultrasonic welding sealer.

[0056] The shank 5 is formed by connecting two cylinders of different diameters, and the whole is in the form of a stepped shaft. Figure 10 As shown, the lower cylinder has a diameter of 42 mm and a height of 5 mm, and the upper cylinder has a diameter of 25 mm and a height of 50 mm. In addition, there are four countersunk holes 5-1 on the lower cylinder, with a countersunk diameter of 6 mm and a thickness of 3 mm, a through hole diameter of 3 mm and a thickness of 2 mm, and each edge is rounded with a fillet radius of 0.5 mm.

[0057] The base 1 and the tool shank 5 are assembled with the help of the countersunk hole and the M3×6 bolt 6, and the runout and coaxiality are made to meet the requirements, thus forming an axial oscillating heat pipe grinding wheel with a heat input end gradient foam metal reinforcement that can be used for grinding. When the workpiece is ground using the axial rotating oscillating heat pipe grinding wheel and the non-axial oscillating heat pipe grinding wheel with a heat input end gradient foam metal reinforcement, the heat flux density is 1×10 8 W / mm 2 Schematic diagram of the simulation of the heat transfer effect of the two grinding wheels on the workpiece, as shown in Figure 11 As shown in the figure, the maximum temperature in the grinding arc zone of the non-oscillating heat pipe grinding wheel reached 1367°C, while the axially oscillating heat pipe grinding wheel reinforced with gradient metal foam at the heat input end controlled the maximum temperature in the grinding arc zone to 659°C, a 52% reduction. Therefore, this new grinding wheel has excellent heat transfer performance and can drain more heat from the grinding arc zone than the non-axially oscillating heat pipe grinding wheel, resulting in lower grinding temperatures and preventing thermal damage to the workpiece surface.

[0058] It can be seen from the technical solutions provided by the present invention that the present invention has the following beneficial effects:

[0059] (1) The axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end proposed in the present invention not only significantly promotes phase change heat transfer in the pipe, but also effectively avoids the occurrence of local dry-out phenomenon, broadens the working range of the axial oscillating heat pipe grinding wheel, and improves its working stability by embedding gradient foam metal at the position of the oscillating heat pipe flow channel corresponding to the heat input end.

[0060] (2) The grinding wheel base is designed and manufactured by combining lattice structure and 3D printing technology, so the overall mechanical and thermal properties of the grinding wheel will become better, and it can also be lightweight and reduce energy consumption.

[0061] (3) The gradient metal foam embedded in the oscillating heat pipe flow channel gradually increases in pore size and porosity from the flow channel wall to the flow channel center, while its hydrophilicity gradually decreases, forming a hollow trumpet-shaped structure with gradually increasing material thickness vertically downward along the grinding wheel axis. The high density of the metal foam in the annular tube cavity hinders the backflow of the gas working medium after liquefaction, while the hollow trumpet-shaped structure does not have to worry about the backflow problem at all. In addition, the closer to the wall, the stronger the hydrophilicity of the metal foam, which can further enhance the boiling heat transfer, while the closer to the center of the flow channel, the stronger its hydrophobicity, which can further promote the flow of bubbles, so that the grinding wheel can still maintain good heat transfer performance under high centrifugal acceleration, increasing working stability.

[0062] (4) The pore size of the filled foam metal has a gradient change structure. The gradient change structure of the foam metal can promote the accelerated bubbles to smoothly escape from it, which effectively prevents the accumulation of bubbles, avoids the increase of thermal resistance and the occurrence of local burning.

[0063] In summary, the present invention embeds gradient foam metal at the heat input end of the oscillating heat pipe flow channel in the grinding wheel, which not only significantly enhances the phase change heat transfer of the working medium inside the grinding wheel during the grinding process, but also effectively avoids the occurrence of local burning-out phenomenon, broadens the working range of the axial oscillating heat pipe grinding wheel, and improves its working stability.

[0064] The above description of the various embodiments of the present application is provided to those skilled in the art for the purpose of description. It is not intended to be exhaustive or to limit the present invention to a single disclosed embodiment. As mentioned above, various substitutions or variations of the present application will be apparent to those skilled in the art of the above-mentioned technology. Therefore, although some alternative embodiments have been specifically discussed, other embodiments will be apparent, or those skilled in the art will find it relatively easy. The present application is intended to include all substitutions, modifications, and variations of the present invention discussed herein, as well as other embodiments that fall within the spirit and scope of the above-mentioned application.

[0065] Although the present application has been described through embodiments, those skilled in the art will appreciate that there are many modifications and variations to the present application without departing from the spirit of the present application. It is intended that the appended claims include these modifications and variations without departing from the spirit of the present application.

Claims

1. An axial oscillating heat pipe grinding wheel with gradient foam metal reinforcement at the heat input end, characterized in that: The grinding wheel comprises: a base, a cover plate, a tool bar, a working medium, an abrasive layer, and a gradient foam metal; The grinding wheel base is a hollow cylinder with a honeycomb structure (1-4) in the middle area; a heat output end of the base is provided with a heat dissipation fin (1-2), and an abrasive layer (4) with abrasives arranged in an orderly manner is electroplated or brazed on the working surface of the grinding wheel; a cover plate (3) is provided on the top of the grinding wheel base to seal the base, and a tool rod (5) is connected to the cover plate at one end in an assembled manner and connected to the main shaft of the machine tool at the other end to drive the grinding wheel to rotate around its own axis; There are multiple loops of oscillating heat pipe flow channels (1-1) inside the grinding wheel base, and working fluid is injected into the oscillating heat pipe flow channels; the flow channels include a direct flow channel (1-1-1) and a connecting flow channel (1-1-2), and the gradient foam metal (2) is placed in the direct flow channel, and the outer cylindrical surface of the gradient foam metal is tightly fitted with the wall surface of the flow channel; during the grinding process, the gradient foam metal in the grinding wheel increases the density of the vaporization core in the flow channel due to its porous structure characteristics, while accelerating the separation of bubbles in the nucleate boiling process, promoting phase change heat transfer in the tube, and effectively avoiding the occurrence of local drying out.

2. The axial oscillating heat pipe grinding wheel with a heat input end gradient metal foam reinforcement according to claim 1, characterized in that: The number of loops of the oscillating heat pipe flow channel is six; the number of direct flow channels and connecting flow channels is 12; the working fluids include: water, methanol and acetone.

3. The axial oscillating heat pipe grinding wheel with a heat input end gradient metal foam reinforcement according to claim 1, characterized in that: The honeycomb structure (1-4) is a hexagonal lattice with a bottom surface flush with the bottom of the substrate. It is obtained by combining lattice structure optimization design with 3D printing technology. The 3D printing technology includes laser powder bed melting technology and laser directed energy deposition technology.

4. The axial oscillating heat pipe grinding wheel with a heat input end gradient metal foam reinforcement according to claim 1, characterized in that: The gradient foam metal (2) is hollow and trumpet-shaped as a whole, with the wall thickness increasing toward the bottom, and the bottom being flush with the bottom of the direct current flow channel; from the wall surface to the center of the oscillating heat pipe flow channel, the pore size gradually increases from the submicron level to the submillimeter level, and the porosity also gradually increases; a layer of structural silver glue with a high thermal conductivity coefficient is evenly applied on the outer cylindrical surface of the gradient foam metal.

5. The axial oscillating heat pipe grinding wheel with a heat input end gradient metal foam reinforcement according to claim 4, characterized in that: The materials of gradient foam metal include: foam copper, foam steel or foam nickel; from the wall to the center of the oscillating heat pipe flow channel, the pore size changes gradually between 30ppi-30000ppi, the porosity changes gradually between 75%-98%, and the through-porosity is ≥90%.

6. The axial oscillating heat pipe grinding wheel with a heat input end gradient metal foam reinforcement according to claim 4, characterized in that: The material of the gradient foam metal is foam copper; from the wall to the center of the oscillating heat pipe flow channel, the pore size gradually increases from 30,000 ppi to 30 ppi, the porosity gradually increases from 90% to 98%, and the through-porosity is 98%.

7. The axial oscillating heat pipe grinding wheel with a heat input end gradient metal foam reinforcement according to claim 1, characterized in that: There are a total of 6 heat dissipation fins (1-2), wherein the thickness of the top fin is greater than that of the other fins, the spacing between the two fins is in a non-contact state, and there is a groove between the heat dissipation fin and the base.

8. The method for preparing an axial oscillating heat pipe grinding wheel reinforced with gradient foam metal at the heat input end according to claim 1, characterized in that: Here are the steps: Step 1: Based on the actual grinding process requirements, the lattice structure and 3D printing technology are used to optimize the design and process the oscillating heat pipe grinding wheel base. The grinding wheel base is a hollow cylinder with a honeycomb structure in the middle area. The grinding wheel base is equipped with a multi-loop oscillating heat pipe flow channel, a vacuum injection pipe at the heat input end, and one or more heat dissipation fins at the heat output end. Step 2: Process the gradient metal foam, which is hollow and trumpet-shaped as a whole, with increasing wall thickness towards the bottom. From the wall to the center of the oscillating heat pipe flow channel, the pore size gradually increases from submicron to submillimeter, and the porosity also gradually increases. Then, apply a layer of structural silver glue with high thermal conductivity to its outer surface and embed it into the multi-circuit flow channel at the heat input end of the oscillating heat pipe grinding wheel, so that its bottom is flush with the bottom of the direct flow channel. Then, heat and dry the grinding wheel base to ensure that the gradient metal foam fits tightly to the wall of the oscillating heat pipe flow channel. Step 3: Weld the cover plate to the grinding wheel base to form an integrated structure. After welding, perform a leak test to ensure good airtightness. Then, use electroplating or brazing technology to plate or weld superhard abrasives with high thermal conductivity on the working surface of the grinding wheel base. Superhard abrasives include diamond or cubic boron nitride (CBN). Step 4: Build a vacuum injection system that matches the oscillating heat pipe flow channel in the grinding wheel base, connect the system to the vacuum injection pipeline on the base, first evacuate the multi-circuit pipeline to a low vacuum degree, and then inject the heat transfer medium suitable for the grinding working conditions into the flow channel. The injection amount of the medium must also be adapted. After the injection is completed, perform the tail sealing work; Step 5: Connect one end of the tool bar to the cover plate with bolts, and the other end to the machine tool spindle, thereby driving the grinding wheel to rotate around its own axis.

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