Efficient cooling grinding wheel applied to ultrasonic machining

Abstract

The invention discloses an efficient cooling grinding wheel applied to ultrasonic machining, and relates to the technical field of ultrasonic auxiliary grinding machining tools, the efficient cooling grinding wheel comprises an upper ultrasonic grinding wheel base rod and a lower ultrasonic grinding wheel grinding head, and the ultrasonic grinding wheel base rod and the ultrasonic grinding wheel grinding head are of an integrated structure; the interior of the ultrasonic grinding wheel base rod is hollow and extends to the bottom of the ultrasonic grinding wheel grinding head without penetrating, the interior of the ultrasonic grinding wheel base rod is in threaded connection or interference fit with a sleeve, the interior of the sleeve is hollow and serves as a main cooling liquid flow channel, the diameter of the interior of the sleeve is the main cooling liquid flow channel, and the diameter of the main flow channel can be changed; a plurality of round holes are formed in the grinding wheel grinding head to serve as cooling liquid flow channels of the grinding head, inlets of the cooling liquid flow channels of the grinding head are connected with the tail end of the main cooling liquid flow channel, outlets of the cooling liquid flow channels of the grinding head are located at the machining position in the grinding process, and cooling liquid grooves are machined in the cooling liquid outlets of the grinding head. And inner cavities of the main cooling liquid flow channel and the grinding head cooling liquid flow channel are provided with rifling structures with variable screw pitches and variable number.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic-assisted grinding tools, and more particularly to an efficient cooling grinding wheel applied to ultrasonic machining. Background Art

[0002] The grinding wheel is the most important machining tool in grinding, directly acting on the workpiece. Through the rotation of the grinding wheel, the abrasive grains on the grinding wheel cut the surface of the workpiece to achieve the removal of the workpiece material. In traditional grinding, a large amount of heat is generated due to the relative movement between the workpiece and the grinding wheel. This not only causes burns on the workpiece surface, residual stress and microcracks, but also may shorten the service life of the grinding wheel and reduce the machining efficiency. Ultrasonic-assisted grinding is a machining method in which the grinding wheel performs high-frequency vibration while rotating and grinding to achieve the removal of the workpiece material. Ultrasonic machining is a process in which a high-frequency electrical oscillation signal generated by an ultrasonic generator is converted into an ultrasonic-frequency mechanical vibration by an ultrasonic transducer. The ultrasonic vibration amplitude is amplified by a horn and then drives the tool grinding wheel to generate vibrations at a corresponding frequency, forming a periodic machining between the tool and the workpiece, which is widely used in ultra-precision machining and manufacturing.

[0003] Ultrasonic-assisted grinding improves the performance of traditional grinding, forming a "micro-lubrication" effect between the grinding wheel and the workpiece, reducing the friction coefficient, and thus reducing the grinding force. Through the assistance of ultrasonic waves, the grinding wheel can more effectively break the microstructure of the material, thereby accelerating the material removal process. Especially in the machining of hard and brittle materials such as ceramics, glass and composite materials, the material removal rate is significantly improved. In addition, due to the intermittent contact caused by vibration, heat accumulation is reduced, effectively avoiding thermal damage and improving the dimensional accuracy and surface integrity of the workpiece.

[0004] However, the introduction of ultrasonic-assisted machining still generates a large amount of grinding heat due to the high-speed scratching between the abrasive grains and the workpiece. If the heat cannot be dissipated in a timely and effective manner, many defects will be caused on the workpiece surface, affecting the machining quality. Especially during deep cutting, more grinding heat will be generated. Therefore, the heat dissipation problem of the grinding wheel is of crucial importance. Currently, ultrasonic-assisted grinding using ordinary grinding wheels usually adopts the cooling method of adding external coolant. Due to the air barrier effect caused by the high-speed rotation of the grinding wheel, the coolant generally only cools near the machining area, and only a small number can enter the interior of the machining area. The cooling effect is limited and the utilization rate of the coolant is low. Therefore, the cooling and heat dissipation problem of ultrasonic-assisted grinding needs to be solved urgently. In addition, in ultrasonic-assisted grinding, due to the high-frequency vibration of the grinding wheel, the grinding wheel not only scratches the workpiece but also impacts the workpiece, so more grinding chips are generated and the volume of the grinding chips is larger. The presence of a large amount of debris will significantly reduce the surface quality of the machined workpiece. Ultrasonic-assisted grinding using traditional grinding wheels does not consider the problem of chip removal. Although there is external coolant injection, the flow rate of the external coolant is low and cannot carry out all the grinding debris, which is a problem that needs to be solved in current ultrasonic-assisted grinding. Summary of the Invention

[0005] In order to overcome the problems that traditional externally added coolant cannot effectively cool the grinding working area and grinding debris is not easy to remove, etc., a high-efficiency cooling grinding wheel applied to ultrasonic machining is provided. An ultrasonic cavitation action chamber is arranged inside the sleeve cavity of the present invention. The strong impact micro-jet generated by ultrasonic waves is used to carry away the grinding debris, prevent the grinding debris from damaging the machined surface, increase the rifling to improve the internal cooling efficiency of the grinding wheel, and the flow rate can be adjusted by the pitch and quantity of the rifling. The abrasive grains of the grinding wheel are hydrophilized, which is beneficial to improving the utilization rate of the coolant. Designing the size of the grinding wheel according to the nodes and antinodes of the standing wave in accordance with ultrasonic parameters is beneficial to maximizing the ultrasonic amplitude and improving the material removal rate.

[0006] The technical means adopted by the present invention are as follows: A high-efficiency cooling grinding wheel applied to ultrasonic machining, including an upper ultrasonic grinding wheel base rod and a lower ultrasonic grinding wheel grinding head. The ultrasonic grinding wheel base rod and the ultrasonic grinding wheel grinding head are of an integral structure; a coaxial hole is arranged inside the ultrasonic grinding wheel base rod and extends to the bottom of the ultrasonic grinding wheel grinding head but does not penetrate. A sleeve is connected inside the ultrasonic grinding wheel base rod by interference fit or thread connection. The inside of the sleeve is a hollow structure with a preset inner diameter specification, serving as the main coolant flow channel; a number of round holes are evenly distributed inside the ultrasonic grinding wheel grinding head as the coolant flow channels of the grinding head. The inlet of the coolant flow channel of the grinding head is connected to the end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is located at the grinding machining position. A coolant groove is machined at the outlet of the coolant flow channel of the grinding head; a rifling structure is arranged inside the main coolant flow channel and the coolant flow channel of the grinding head.

[0007] Further, the coolant flow channel of the grinding head forms a certain angle with the main coolant flow channel. According to different formed angles, it is divided into an upper end face type structure, a lower end face type structure, and a side face type structure. For the upper end face type structure, the inlet of the coolant flow channel of the grinding head is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the upper end face of the grinding part of the grinding wheel; For the lower end face type structure, the inlet of the coolant flow channel of the grinding head is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the lower end face of the grinding part of the grinding wheel; For the side face type structure, the inlet of the coolant flow channel of the grinding head is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the side face of the grinding part of the grinding wheel.

[0008] Further, the diameter of the hollow structure inside the sleeve can be changed, specifically including a stepped variable diameter type and an arc variable diameter type.

[0009] Further, a cavity is arranged at the lower end of the sleeve, serving as an ultrasonic cavitation action chamber.

[0010] Furthermore, the rifling rotation direction and angle of the main coolant channel are the same as those of the coolant channel of the grinding head. The types of rifling include uniform rifling, progressive rifling, hybrid rifling, constant-width rifling, and wedge rifling.

[0011] Furthermore, the cross-section of the coolant channel of the grinding head is circular, and its diameter does not exceed 1 / 3 of the thickness of the ultrasonic grinding wheel head. The shapes and sizes of the coolant grooves are the same, and the shapes of the coolant grooves include straight lines, curves, or preset irregular lines.

[0012] Furthermore, the outer surface of the grinding wheel is processed by electroplating, coating, or ion implantation to obtain a hydrophilic grinding wheel surface, and both the grinding wheel surface and the abrasive grains are hydrophilic.

[0013] Furthermore, the shapes and sizes of the round holes are the same, and the angles formed by each round hole and the main coolant channel are the same. Each round hole is evenly distributed along the circumference of the grinding part of the grinding wheel.

[0014] Furthermore, the shapes and sizes of the coolant grooves are the same, and the shapes of the coolant grooves include straight lines, curves, or preset irregular lines.

[0015] Furthermore, the total length L of the grinding wheel, the total width d of the ultrasonic grinding wheel head, and the height h of the ultrasonic grinding wheel head are determined by applying the longitudinal vibration principle of a variable cross-section rod and the vibration distribution characteristics of ultrasonic vibration nodes and antinodes. At the corresponding position of the central axis of the grinding wheel, the lateral edge of the ultrasonic grinding wheel head corresponds to the antinode position, and the radius of the ultrasonic grinding wheel head is an integer multiple of 1 / 2 wavelength; at the longitudinal upper and lower edges of the ultrasonic grinding wheel head, they correspond to the antinode positions, and the height of the ultrasonic grinding wheel head is an integer multiple of 1 / 2 wavelength; at the upper edge of the base rod of the ultrasonic grinding wheel, it corresponds to the node position, and at the lower edge, it corresponds to the antinode position, and the length of the base rod of the ultrasonic grinding wheel is an integer multiple of 1 / 2 wavelength plus 1 / 4 wavelength.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The main coolant channel obtains coolant through the machine tool. The coolant first passes through the grinding wheel base and the ultrasonic grinding wheel head, effectively reducing the temperature of the grinding wheel. Then, under the action of pressure and the rotation of the grinding wheel, it is directly ejected from the surface of the grinding part of the grinding wheel through the coolant channel of the grinding head in the grinding area, cooling, lubricating, and flushing the grinding area, which can effectively reduce the grinding temperature, improve the surface quality of the machining, and the grindability. In addition, the effective utilization of the coolant can also play a role in lubricating the grinding area, reducing the friction in the grinding area, and reducing the generation of grinding heat.

[0017] 2. The present invention adopts an internal cooling method. By arranging a main coolant flow channel inside the grinding wheel base body, a sleeve with a variable diameter is nested in the ultrasonic grinding wheel base rod. Different variable diameter schemes can be designed according to processing requirements. When increasing the speed, the diameter is designed to gradually decrease, and when decreasing the speed, the diameter is designed to gradually increase. A smooth transition scheme can also be designed. The design of the internally placed sleeve with a variable diameter is relatively flexible, meeting different processing requirements.

[0018] 3. An ultrasonic cavitation effect chamber is designed inside the sleeve cavity. Utilizing the cavitation effect of ultrasound, in a reaction chamber with a low pressure, when the ultrasonic energy is high enough at this time, the tiny bubbles existing in the coolant vibrate, expand, and continuously accumulate energy under the action of the ultrasonic field. The cavitation bubbles suddenly collapse and explode in places with a larger pressure, forming a powerful impact force and micro-jet flow, solving the problem that grinding debris reduces the surface quality of the workpiece.

[0019] 4. Designing rifling can overall accelerate the flow rate and enhance the cooling effect, and can also control the utilization rate and flow rate of the coolant according to the pitch and number of rifling, enabling better control of the use of the coolant during processing. Local rifling can also be machined at the places where acceleration is desired, which is more flexible in using the existing coolant.

[0020] 5. The grinding wheel with a lower end face structure can grind traditional planes, the side face structure can grind the inner wall of the holes of workpieces, and the upper end face structure can grind the upper walls of the grooves of some workpieces. The present invention can solve the cooling and temperature control problems for multiple uses of the grinding wheel.

[0021] 6. The hydrophilic treatment is added to the surface of the grinding wheel, further improving the cooling efficiency on the basis of the existing machine tool processing.

[0022] 7. The present invention provides a new calculation method for the tool size used in ultrasonic processing, solving the drawbacks of the current grinding wheel selected by experience. Applying scientific designs such as nodes and antinodes, making the positions that need to enhance the amplitude correspond to antinodes and the positions that need to reduce interference correspond to nodes, improving the amplitude of processing and achieving the gain effect of ultrasonic assisted processing.

[0023] In summary, the present invention can design the unique grinding wheel size of ultrasound, directly cool the inside of the grinding wheel under the grinding working state, and can also directly cool, lubricate, and flush the inside of the grinding wheel and the grinding processing area. The cooling effect and speed of the coolant can be adjusted. The ultrasonic cavitation effect can be utilized to prevent the coolant from being blocked, reduce the influence of the gas barrier effect, while also improving the cooling effect and the grinding processability. Description of the Drawings

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0025] Figure 1 This is the sectional view of the overall structure in the embodiment of the present invention.

[0026] Figure 2 This is the schematic diagram of the overall structure in the embodiment of the present invention.

[0027] Figure 3 This is the sectional view of various stepped-diameter sleeves in the embodiment of the present invention.

[0028] Figure 4 This is the sectional view of the ultrasonic cavitation chamber structure in the embodiment of the present invention.

[0029] Figure 5 This is the sectional view of the rifling structure in the embodiment of the present invention.

[0030] Figure 6 This is the sectional view of the coolant flow channels at different angles in the embodiment of the present invention.

[0031] Figure 7 This is the sectional view of the grinding wheel size in the embodiment of the present invention.

[0032] In the figure: 1. Ultrasonic grinding wheel base rod, 2. Sleeve, 3. Main coolant flow channel, 4. Ultrasonic grinding wheel grinding head, 5. Grinding head coolant flow channel, 6. Grinding head rifling, 7. Hexagonal groove, 8. Abrasive grain, 9. Coolant groove, 10. Threaded connection, 11. Accelerating stepped-diameter main flow channel, 12. Decelerating stepped-diameter main flow channel, 13. Arc-shaped stepped-diameter main flow channel, 14. Main flow channel rifling, 15. Ultrasonic cavitation chamber, 16. Main coolant flow channel outlet, 17. Grinding head coolant flow channel inlet, 18. Upper end face structure, 19. Lower end face structure, 20. Side face structure. Detailed implementation manners

[0033] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The following will describe the present invention in detail with reference to the accompanying drawings and in combination with the embodiments.

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. The following description of at least one exemplary embodiment is actually illustrative only and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0035] It should be noted that the terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly dictates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationship. Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0037] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. are generally based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the scope of protection of the present invention. The orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0038] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. can be used here to describe the spatial positional relationship of a device or feature shown in the figure with other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figure for the device. For example, if the device in the attached drawing is inverted, the device described as "above" or "over" other devices or structures will then be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations are made for the spatial relative descriptions used here.

[0039] In addition, it should be noted that using terms such as "first", "second" to limit components is merely for the convenience of differentiating the corresponding components. Without additional statements, the above terms have no special meanings, so they cannot be construed as limiting the protection scope of the present invention.

[0040] As Figure 1 shown, an embodiment of the present invention discloses an efficient cooling grinding wheel applied to ultrasonic machining, including an upper ultrasonic grinding wheel base rod 1 and a lower ultrasonic grinding wheel grinding head 4. The upper end of the ultrasonic grinding wheel base rod is connected to the spindle of an internal cooling grinding machine tool, and the machine tool body is connected to an ultrasonic tool shank through the spindle. The ultrasonic tool shank also receives the electrical signal emitted by an ultrasonic generator. This ultrasonic machining technology is a conventional technology in the prior art, that is, the technology pointed out in the background art; The ultrasonic grinding wheel base rod and the ultrasonic grinding wheel grinding head are of an integral structure; a coaxial hole is provided inside the ultrasonic grinding wheel base rod and extends to the bottom of the ultrasonic grinding wheel grinding head but does not penetrate. A sleeve 2 is connected inside the ultrasonic grinding wheel base rod by interference fit or screw connection. The inside of the sleeve is a hollow structure with a preset inner diameter as the main coolant flow channel 3; a number of circular holes are evenly distributed inside the ultrasonic grinding wheel grinding head as the grinding head coolant flow channels 5. The entrances of the grinding head coolant flow channels are connected to the end of the main coolant flow channel, and the exits of the grinding head coolant flow channels are located at the grinding processing position. Coolant grooves 9 are machined at the exits of the grinding head coolant flow channels; rifling 6 of the grinding head is provided in the inner cavities of the main coolant flow channel and the grinding head coolant flow channels. In this embodiment, the number of circular holes is 3 - 6.

[0041] In the existing cooling mode of the externally grooved grinding wheel, the cooling surface cannot be accurately controlled. Therefore, in the embodiments of the present invention, the inside of the grinding wheel is cooled, and at the same time, the positions and numbers of the coolant holes and coolant grooves can be changed. The coolant flow channel of the grinding head forms a certain angle with the main coolant flow channel, and is divided into an upper-end surface type structure, a lower-end surface type structure, and a side surface type structure according to different formed angles. The inlet of the coolant flow channel of the grinding head of the upper-end surface type structure is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the upper end surface of the grinding part of the grinding wheel. The inlet of the coolant flow channel of the grinding head of the lower-end surface type structure is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the lower end surface of the grinding part of the grinding wheel. The inlet of the coolant flow channel of the grinding head of the side surface type structure is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the side surface of the grinding part of the grinding wheel.

[0042] The present invention can accurately cool the machining position and improve the utilization rate of the coolant.

[0043] Specifically, as Figure 6 shown, the input ends of the coolant flow channels of the grinding heads are all connected to the main coolant flow channel, and the outlets of the coolant flow channels all have coolant grooves arranged along the side surface of the grinding part of the grinding wheel. The coolant flow channels of the grinding heads form angles in three directions, and are divided into an upper-end surface type structure 18, a lower-end surface type structure 19, and a side surface type structure 20 according to different formed angles. The outlet of the coolant flow channel of the upper-end surface type structure 18 is arranged on the upper end surface of the grinding part of the grinding wheel, and the included angle is 45 degrees. The outlet of the coolant flow channel of the lower-end surface type structure 19 is arranged on the lower end surface of the grinding part of the grinding wheel, and the included angle is 45 degrees. The outlet of the coolant flow channel of the side surface type structure 20 is arranged on the side surface of the grinding part of the grinding wheel, and the included angle is 90 degrees. The shapes and sizes of the coolant flow channels of the grinding heads are the same, and the angle formed by each coolant flow channel of the grinding head and the main coolant flow channel is the same. The coolant flow channels of the grinding heads are evenly distributed along the circumferential direction of the grinding part of the grinding wheel, which is convenient for the machining of the coolant flow channels. The shapes and sizes of the coolant grooves 9 are the same, and the shapes of the coolant grooves include straight lines, curves or preset irregular lines.

[0044] As mentioned above, the inside of the sleeve is a hollow structure with a preset standard inner diameter, and the hollow structure with the preset standard inner diameter can be an equal-diameter structure.

[0045] As a preferred embodiment, the diameter of the hollow structure inside the sleeve can be changed, specifically including a stepped variable diameter type and an arc variable diameter type, that is, a variable diameter structure, as a variable diameter sleeve. Specifically, as Figure 3As shown in the figure, a variable-diameter sleeve with a variable inner diameter is nested inside the ultrasonic grinding wheel base rod 1. The internal design of the variable-diameter sleeve is diverse, including different forms such as an accelerating stepped variable-diameter main flow channel 11, a decelerating stepped variable-diameter main flow channel 12, and an arc-shaped variable-diameter main flow channel 13, etc., to achieve the acceleration and deceleration, and irregular variable speed of the coolant. The variable-diameter sleeve can be made of plastic material and nested into the inner wall of the ultrasonic grinding wheel base rod at low temperature. At room temperature, the variable-diameter sleeve and the ultrasonic grinding wheel base rod form an interference fit. Or as Figure 2 shown, the variable-diameter sleeve can also be processed with metal materials. External threads are processed at the upper end outlet of the variable-diameter sleeve, and internal threads are processed at the upper end outlet of the ultrasonic grinding wheel base rod. A threaded connection 10 is used between the ultrasonic grinding wheel base rod and the variable-diameter sleeve. A hexagonal groove 7 is processed at the upper end outlet of the variable-diameter sleeve, and a hexagonal wrench can be used to install the variable-diameter sleeve. The above-mentioned accelerating stepped variable-diameter specifically means that the diameter of the variable-diameter sleeve gradually decreases from the upper end of the ultrasonic grinding wheel base rod to the grinding head of the ultrasonic grinding wheel, and the change is in a stepped shape. The above-mentioned decelerating stepped variable-diameter specifically means that the diameter of the variable-diameter sleeve gradually increases from the upper end of the ultrasonic grinding wheel base rod to the grinding head of the ultrasonic grinding wheel, and the change is in a stepped shape. The irregular variable speed can be the circular arc variable speed shown in the figure, that is, the diameter of the variable-diameter sleeve gradually increases from the upper end of the ultrasonic grinding wheel base rod to the grinding head of the ultrasonic grinding wheel, and the inside of the sleeve has a smooth arc transition.

[0046] Furthermore, a cavity is provided at the lower end of the variable-diameter sleeve as an ultrasonic cavitation chamber. Specifically, as Figure 4 shown, a structure of an ultrasonic cavitation sleeve suitable for ultrasonic-assisted machining is designed in the variable-diameter sleeve. The diameters at the upper end of the variable-diameter sleeve and the coolant flow channel of the grinding head are small, and the inner wall is processed with main flow channel rifling 14, and it is in an environment of high pressure and high flow rate. The cavity at the lower end of the variable-diameter sleeve serves as the ultrasonic cavitation chamber 15 and is in a low-pressure environment. Tiny bubble nuclei in the liquid generate vibrations under the action of ultrasonic waves. When the pressure reaches a certain value, the bubbles will rapidly expand and then suddenly close. When the bubbles close, shock waves are generated. This series of dynamic processes such as expansion, closing, and oscillation. The role of the ultrasonic cavitation reaction is to form a powerful impact force and micro-jet. During the grinding process, the outflow of the coolant may be blocked by the workpiece and chips. This design can wash away the processing debris in time, prevent its influence on the surface quality, avoid grinding wheel clogging, and take away the chips in time to improve the grinding quality.

[0047] Specifically, the ultrasonic tool holder converts the high-frequency electrical signal into mechanical vibration of ultrasonic frequency through the built-in ultrasonic transducer, and then amplifies the vibration amplitude through the horn and transmits it to the grinding wheel.

[0048] When ultrasonic vibration is transmitted through the ultrasonic grinding wheel base rod to the coolant in the cavitation chamber inside the ultrasonic grinding wheel base rod, since ultrasonic waves propagate in the form of longitudinal waves, the liquid particles will experience alternating dense and sparse states during propagation. In the sparse state, the liquid particles are subjected to tensile force. When the tensile force exceeds the static pressure of the liquid, vacuum cavities, that is, bubbles, will be formed inside the liquid. The formed bubbles will undergo periodic oscillatory motion under the action of ultrasonic waves. In the sparse part of the sound wave, the bubbles will expand; in the dense part of the sound wave, the bubbles will contract. As the ultrasonic intensity increases, the oscillation amplitude of the bubbles gradually increases. When the ultrasonic energy reaches a sufficiently high level, the oscillation of the bubbles will become very intense. At this time, the vibration of the bubbles is controlled by the inertia of the surrounding medium, and it will expand rapidly in the negative pressure phase half cycle of the sound wave and contract sharply in the positive pressure phase half cycle of the sound wave, eventually leading to the rupture of the bubbles. When the bubbles rupture, the gas inside will quickly diffuse into the surrounding liquid, and at the same time, high pressure and strong shock waves will be generated. These high-pressure shock waves will produce a series of physical effects on the surrounding area, and can generate liquid microjets with speeds up to hundreds of meters per second, which impact the machining position and carry away the chips.

[0049] The upper end of the stepped sleeve and the coolant flow channel of the grinding head have a small diameter, and the inner wall is machined with rifling, and it is in an environment of high pressure and high flow rate. The lower cavity of the stepped sleeve serves as the ultrasonic cavitation chamber and is in a low-pressure environment. The role of the ultrasonic cavitation reaction is to form a powerful impact force and microjet, which can quickly remove the fine debris during grinding and prevent the debris from adhering to the machining area and reducing the surface quality of the workpiece.

[0050] As Figure 5 shown, rifling designs are added to the inner walls of the coolant main flow channel and the coolant flow channel of the grinding head. Further, the helix direction and angle of the rifling in the coolant main flow channel are the same as those of the coolant flow channel of the grinding head. The types of rifling include uniform rifling, progressive rifling, hybrid rifling, constant-width rifling, and wedge rifling. The rifling makes the coolant rotate around the inner wall and fully contact the inside of the grinding wheel, avoiding uneven heat dissipation caused by the coolant flowing down one side and improving the internal cooling effect. The pitch of the rifling is used to adjust the coolant flow rate. The larger the pitch, the faster the flow rate; the smaller the pitch, the slower the flow rate. The number of rifling grooves is used to adjust the cooling effect. The more the number of grooves, the better the cooling effect. In this example, a design with a 25-pitch and four rifling grooves is adopted. The outlet 16 of the coolant main flow channel in the stepped sleeve corresponds to the inlet 17 of the coolant flow channel of the grinding head and has the same helix direction to ensure that the coolant flow rate is inherited. Rifling structures are machined in the main flow channel and the coolant flow channel of the grinding head. The machining methods of rifling include scraping method, broaching method with a hook tool, and cold extrusion method.

[0051] Further, the cross-section of the coolant flow channel of the grinding head is circular, and the diameter does not exceed 1 / 3 of the thickness of the ultrasonic grinding wheel head. The shapes and sizes of the coolant grooves are the same, and the shapes of the coolant grooves include straight lines, curves, or preset irregular lines.

[0052] Furthermore, the outer surface of the abrasive grains of the grinding wheel is processed by electroplating, coating or ion implantation to produce a hydrophilic surface of the grinding wheel. Both the surface of the grinding wheel and the abrasive grains 8 are hydrophilic. After the grinding wheel processed by electroplating wears, new abrasive grains are exposed, and the hydrophilic process can be carried out twice or multiple times to ensure hydrophilicity. The hydrophilic process can make more coolant stay in the gaps between the abrasive grains of the grinding wheel, and the cooling can be carried out more efficiently during the grinding process.

[0053] Furthermore, the shapes and sizes of the round holes are the same, and the angles formed by each round hole and the main coolant flow channel are the same. Each round hole is evenly distributed along the circumferential direction of the grinding part of the grinding wheel.

[0054] Furthermore, the shapes and sizes of the coolant grooves are the same, and the shapes of the coolant grooves include straight lines, curves or preset irregular lines. The specific opening size of the present invention can be adjusted and designed according to the temperature control requirements, and the main cutting fluid flow channel is arranged to ensure that the cutting fluid fully enters the cutting holes and ensure the cooling effect. It solves the problems in the prior art that the opening processing of the patent is difficult, and when the opening is too small and the grinding wheel rotates at a high speed, due to the air barrier effect, very little cutting fluid enters the hole, and the cooling effect is limited.

[0055] As Figure 7 shown, standing wave curves will be generated in ultrasonic machining. The transverse ultrasonic and longitudinal ultrasonic can respectively use the nodes and antinodes in the standing wave curves to determine the optimal size of the grinding wheel, maximize the ultrasonic gain, and use the minimum interference characteristics of the nodes and the maximum interference characteristics of the antinodes to determine the total length L of the grinding wheel, the total width d of the ultrasonic grinding head and the height h of the ultrasonic grinding head.

[0056] At the position corresponding to the central axis of the grinding wheel, the transverse edge of the ultrasonic grinding head corresponds to the antinode position. The radius of the ultrasonic grinding head is an integer multiple of 1 / 2 wavelength; the upper and lower edges of the ultrasonic grinding head in the longitudinal direction correspond to the antinode positions, and the height of the ultrasonic grinding head is an integer multiple of 1 / 2 wavelength; the upper edge of the ultrasonic grinding wheel base rod corresponds to the node position, and the lower edge corresponds to the antinode position. The length of the ultrasonic grinding wheel base rod is an integer multiple of 1 / 2 wavelength plus 1 / 4 wavelength.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An efficient cooling grinding wheel applied to ultrasonic machining, characterized in that, It includes an upper ultrasonic grinding wheel base rod and a lower ultrasonic grinding wheel grinding head, and the ultrasonic grinding wheel base rod and the ultrasonic grinding wheel grinding head are of an integral structure; a coaxial hole is arranged inside the ultrasonic grinding wheel base rod and extends to the bottom of the ultrasonic grinding wheel grinding head but does not penetrate. A sleeve is connected inside the ultrasonic grinding wheel base rod by thread connection or interference fit. The inside of the sleeve is a hollow structure with a preset inner diameter specification, serving as the main coolant flow channel; a number of round holes are evenly distributed inside the ultrasonic grinding wheel grinding head as the coolant flow channels of the grinding head. The inlet of the coolant flow channel of the grinding head is connected to the end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is located at the grinding position. A coolant groove is processed at the outlet of the coolant flow channel of the grinding head; a rifling structure is arranged in the inner cavities of the main coolant flow channel and the coolant flow channel of the grinding head; the sleeves nested in the ultrasonic grinding wheel base rod are designed with different variable diameter schemes according to processing requirements; the total length L of the grinding wheel, the total width d of the ultrasonic grinding wheel grinding head, and the height h of the ultrasonic grinding wheel grinding head are determined by applying the longitudinal vibration principle of a variable cross-section rod and the vibration distribution characteristics of ultrasonic vibration nodes and antinodes. At the corresponding position of the grinding wheel central axis, the transverse edge of the ultrasonic grinding wheel grinding head corresponds to the antinode position, and the radius of the ultrasonic grinding wheel grinding head is an integer multiple of 1 / 2 wavelength; the upper and lower longitudinal edges of the ultrasonic grinding wheel grinding head correspond to the antinode positions, and the height of the ultrasonic grinding wheel grinding head is an integer multiple of 1 / 2 wavelength; the upper edge of the ultrasonic grinding wheel base rod corresponds to the node position, and the lower edge corresponds to the antinode position. The length of the ultrasonic grinding wheel base rod is an integer multiple of 1 / 2 wavelength plus 1 / 4 wavelength.

2. The high-efficiency cooling grinding wheel applied to ultrasonic machining according to claim 1, wherein, A cavity is arranged at the lower end of the sleeve, serving as an ultrasonic cavitation action cavity.

3. The high-efficiency cooling grinding wheel applied to ultrasonic processing according to claim 1, characterized in that the coolant flow channels of the grinding head form a certain angle with the main coolant flow channel, and are divided into an upper end face type structure, a lower end face type structure, and a side face type structure according to different formed angles. For the upper end face type structure, the inlet of the coolant flow channel of the grinding head is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the upper end face of the grinding part of the grinding wheel. For the lower end face type structure, the inlet of the coolant flow channel of the grinding head is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the lower end face of the grinding part of the grinding wheel. For the side face type structure, the inlet of the coolant flow channel of the grinding head is connected to the bottom end of the main coolant flow channel, and the outlet of the coolant flow channel of the grinding head is arranged on the side face of the grinding part of the grinding wheel.

4. The high-efficiency cooling grinding wheel applied to ultrasonic machining according to claim 1, characterized in that, The diameter of the hollow structure inside the sleeve can be changed, specifically including a stepped variable diameter type and an arc variable diameter type.

5. The high-efficiency cooling grinding wheel applied to ultrasonic machining according to claim 1, wherein, The rifling helix direction and angle of the main coolant flow channel are the same as those of the coolant flow channel of the grinding head. The rifling types include equal pitch rifling, progressive rifling, hybrid rifling, equal width rifling, and wedge rifling.

6. The high-efficiency cooling grinding wheel applied to ultrasonic machining according to claim 1, wherein The cross-section of the coolant flow channel of the grinding head is circular, and the diameter does not exceed 1 / 3 of the thickness of the ultrasonic grinding wheel grinding head. The shapes and sizes of the coolant grooves are the same, and the shapes of the coolant grooves include straight lines, curves, or preset irregular lines.

7. The high-efficiency cooling grinding wheel applied to ultrasonic machining according to claim 1, wherein The external surface of the grinding wheel is processed by electroplating process, coating process, or ion implantation to have a hydrophilic grinding wheel surface, and both the grinding wheel surface and the abrasive grains are hydrophilic.

8. The high-efficiency cooling grinding wheel applied to ultrasonic machining according to claim 1, wherein The shapes and sizes of the circular holes are the same, and the angle formed by each circular hole and the main coolant flow channel is the same. Each circular hole is evenly distributed along the circumferential direction of the grinding wheel grinding part.

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