Numerically controlled machine tool and method of machining thereof

Abstract

The application relates to the technical field of cutter machining, and discloses a numerical control machine tool cutter and a machining method thereof, wherein the numerical control machine tool cutter comprises a cutter body, a recess is arranged at the working end of the cutter body, the inner wall of the recess forms a step, at least one mounting groove is arranged on the side surface of the step, a first machining cutter is arranged on the outer edge of the top surface of the step, a second machining cutter is arranged on the inner edge of the top surface of the step, at least one positioning column is radially slidably arranged in the mounting groove, and at least one wedge-shaped groove is arranged on the working surface of the sleeve core part and faces the positioning column. The numerical control machine tool cutter and the machining method thereof provide geometric conditions for the establishment of a fluid dynamic pressure liquid film, realize non-contact liquid film guiding, improve the guiding surface precision, and further improve the straightness and precision of a machined deep hole.

Description

Technical Field

[0001] This invention relates to the technical field of cutting tool processing, and in particular to a CNC machine tool and its processing method. Background Technology

[0002] In deep hole machining, cutting tools typically consist of outer cutting teeth and inner cutting teeth. For example, by creating a step by opening a groove at the front end of the tool body, an outer cutting tool located on the top surface of the step is used to machine an annular area on the workpiece and form a central guide core. Subsequently, the inner cutting tool located at the bottom of the groove removes the core, which can effectively solve the problems of heat concentration and chip removal difficulties in traditional deep hole drilling.

[0003] In existing nesting tools, the guide block is radially arranged along the inner wall of the groove to contact the outer cylindrical surface of the nesting core and provide radial positioning support. However, under actual machining conditions, the rigid contact between the guide block and the outer cylindrical surface of the nesting core presents the following problems:

[0004] First, under the combined effects of cutting fluid disturbance and cutting force fluctuation, micro-amplitude high-frequency hammering easily occurs between the guide block and the core of the bushing, leading to a gradual loss of the guide surface accuracy and consequently causing deviations in the straightness of the deep hole. Second, the high-pressure cutting fluid flows at extremely high velocity through the annular gap formed by the bushing cutting tool. Since the core of the bushing is only supported by point contact with the guide block inside the rotating tool, rather than being fully circumferentially clamped, and the length-to-diameter ratio of the core of the bushing is large, when the high-pressure cutting fluid enters the tiny wedge-shaped gap between the guide block and the core of the bushing, an uncontrollable dynamic pressure suspension effect is generated, further exacerbating the instability of the guide state. Under actual working conditions, the guide block will wear polygonal marks on the surface of the core of the bushing due to the above vibrations, resulting in a loss of guide surface accuracy, which in turn causes the tool to lose its positioning reference, ultimately resulting in poor straightness or an oversized hole in the machined deep hole. Summary of the Invention

[0005] Therefore, the purpose of this invention is to overcome the following: the guide block of the deep hole nesting tool and the outer cylindrical surface of the nesting core are in direct metal-to-metal contact sliding, resulting in high friction and easy creeping vibration, which leads to loss of guide surface accuracy and ultimately causes poor straightness or excessive diameter of the machined deep hole. The invention proposes a CNC machine tool and its machining method to provide geometric conditions for the establishment of a hydrodynamic liquid film, realize non-contact liquid film guidance, thereby improving the accuracy of the guide surface and thus improving the straightness and accuracy of the machined deep hole.

[0006] To solve the above-mentioned technical problems, in a first aspect, the present invention provides a CNC machine tool cutting tool, comprising:

[0007] The blade body has a groove at its working end, the inner wall of the groove forms a step, and at least one mounting groove is provided on the side of the step.

[0008] A first processing cutter and a second processing cutter, wherein the first processing cutter is disposed on the outer edge of the top surface of the step, and the second processing cutter is disposed on the inner edge of the top surface of the step;

[0009] At least one positioning post is provided, which is radially slidably mounted in the mounting groove. The positioning post has at least one wedge-shaped groove on its working surface facing the core of the sleeve, and the depth of the wedge-shaped groove decreases along the direction of the cutting fluid flow.

[0010] Secondly, the present invention provides a method for machining CNC machine tool cutting tools, comprising:

[0011] Supply cutting fluid to the wedge-shaped groove;

[0012] The machining tool is started to rotate. When the machining tool speed reaches the preset speed, the machining tool is driven to feed axially. The first machining tool and the second machining tool machine an annular area on the workpiece and form a core. At the same time, the cutting fluid in the wedge groove forms a hydrodynamic fluid film between the working surface of the positioning post and the outer cylindrical surface of the core.

[0013] Thirdly, the present invention provides a machining method for CNC machine tool cutting tools, wherein during deep hole machining, when restarting after an intermediate stop, the method includes:

[0014] High-pressure cutting fluid is introduced into the static pressure chamber to push the positioning column outward radially with static pressure;

[0015] Supply cutting fluid to the wedge-shaped groove;

[0016] The machining tool is started to rotate. When the machining tool speed reaches the preset speed, the high-pressure cutting fluid is cut off from the hydrostatic chamber and the machining tool is driven to feed axially. The first machining tool and the second machining tool machine an annular area on the workpiece and form a core. At the same time, the cutting fluid in the wedge groove forms a hydrodynamic fluid film between the working surface of the positioning post and the outer cylindrical surface of the core.

[0017] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:

[0018] The CNC machine tool cutting tool described in this invention provides the geometric conditions for the establishment of a hydrodynamic film, transforming solid contact friction guidance into a hybrid hydrodynamic-static support. Specifically:

[0019] By incorporating wedge-shaped grooves on the locating post, a converging wedge-shaped gap is formed between it and the surface of the bushing core. During machining, the cutting fluid is dragged into this converging wedge-shaped gap by the relatively rotating bushing core. Furthermore, because the depth of the wedge-shaped groove decreases along the direction of cutting fluid flow, the channel narrows and is subjected to intense compression, generating extremely high local dynamic pressure and forming a hydrodynamic fluid film. This hydrodynamic fluid film, with a thickness of 5μm to 20μm and high rigidity, physically isolates the locating post from the surface of the bushing core, converting solid friction into low-loss fluid shear friction, thereby improving the accuracy of the guide surface and consequently improving the straightness and accuracy of the machined deep hole.

[0020] The machining method for CNC machine tool tools described in this invention avoids initial dry friction between the positioning pin and the core of the workpiece by employing a startup sequence of supplying fluid first and then rotating; and ensures that the cutting load is only borne after the hydrodynamic fluid film is fully established through a preset speed. Specifically:

[0021] Before the machining tool rotates, cutting fluid is pre-supplied to the wedge groove, filling the wedge groove and the working surface area of ​​the locating post with cutting fluid medium. When the spindle starts to rotate, there is already liquid filling between the locating post and the surface of the sleeve core. The relative sliding at the moment of startup occurs within the liquid shear layer, rather than at the metal-metal interface, which reduces the coefficient of friction and wear risk during the startup phase and creates initial conditions for the smooth establishment of the subsequent hydrodynamic fluid film.

[0022] Before reaching the preset speed, the tool rotates but does not feed, and the locating pin and the core of the bushing do not yet bear significant radial cutting load. When the speed reaches the preset speed, the cutting fluid in the wedge groove is fully dragged and squeezed by the rotating core of the bushing, forming a hydrodynamic fluid film with sufficient rigidity in the convergence gap. At this point, when axial feed machining begins, the hydrodynamic fluid film is capable of supporting the radial cutting force, ensuring that the entire machining process is carried out in a stable non-contact guiding state, effectively avoiding boundary friction or guide instability problems caused by insufficient hydrodynamic pressure and weak fluid film bearing capacity at low speed stages.

[0023] The machining method for CNC machine tool tools described in this invention, by setting a static pressure pre-support step, can eliminate the static pre-pressure contact stress established during downtime, thus solving the wedge groove protection problem when restarting after a mid-operational stop. Specifically:

[0024] Before restarting the machining tool rotation, high-pressure cutting fluid is first introduced into the hydrostatic chamber. The hydrostatic pressure pushes the positioning post to produce a slight displacement of 10μm to 30μm in the radial direction. This releases the tight contact between the positioning post and the core surface that was re-established during the shutdown due to the preload force, and allows the sharp edge of the wedge groove to be physically separated from the core surface again. Attached Figure Description

[0025] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0026] Figure 1 This is a schematic diagram of a CNC machine tool cutting tool in an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of a positioning post in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of a cutting tool in the prior art.

[0029] Figure 4 This is a schematic diagram of another structure of a cutting tool in the prior art.

[0030] Figure 5 This is a schematic flowchart of a CNC machine tool cutting method according to an embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram of another process for machining CNC machine tool cutting tools in an embodiment of the present invention.

[0032] Explanation of reference numerals in the accompanying drawings: 1. Tool body; 100. Core of the insert; 11. Working end; 12. Connecting end; 2. Groove; 31. Side; 311. Mounting groove; 312. Clearance channel; 32. Top surface; 41. First machining tool; 42. Second machining tool; 5. Positioning post; 511. Base; 512. Covering layer; 52. Wedge groove; 53. Static pressure channel; 61. Static pressure chamber; 62. Sealing ring; 43. Cutting tool; 7. Chip removal hole. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0034] Example 1: This example discloses a CNC machine tool cutting tool.

[0035] refer to Figures 1 to 4 The CNC machine tool cutting tool of this embodiment includes: a tool body 1, a first machining tool 41, a second machining tool 42, a positioning pin 5, and a hydrostatic chamber 61. Furthermore, the CNC machine tool cutting tool of this embodiment also includes: a first cutting fluid injection device, a second cutting fluid injection device, a sealing ring 62, a cutting tool 43, and a chip removal hole 7.

[0036] In this embodiment, the cutter body 1 includes a working end 11 and a connecting end 12 arranged opposite to each other along the axial direction.

[0037] In application, the connecting end 12 of the cutter body 1 is provided with a connecting thread for detachable connection with the drive mechanism of the CNC machine tool.

[0038] In practical applications, the working end 11 of the cutter body 1 is provided with a cylindrical groove 2 coaxially arranged with the cutter body 1, and an annular step is formed between the inner wall of the groove 2 and the end face of the working end 11. The top surface 32 of the step is an annular plane with an angle greater than or equal to 90° with the axis. The side surface 31 of the step is a cylindrical surface.

[0039] refer to Figures 3 to 4 In this embodiment, both the first processing blade 41 and the second processing blade 42 are mounted on the top surface 32 of the step.

[0040] In application, the first machining tool 41 is located at the radial outer edge of the top surface 32 and is used to machine the outer ring of the sleeve annular region; the second machining tool 42 is located at the radial inner edge of the top surface 32, close to the central axis of the tool body 1, and is used to machine the inner ring of the sleeve annular region. The line connecting the installation positions of the first machining tool 41 and the second machining tool 42 is collinear with a certain diameter of the groove 2 to ensure symmetrical distribution of cutting force.

[0041] In practical applications, both the first machining tool 41 and the second machining tool 42 adopt a clamping structure and are fixed to the preset blade groove on the tool body 1 by countersunk screws.

[0042] In this embodiment, at least one first mounting groove 311 is provided circumferentially on the stepped side 31 of the groove 2.

[0043] In application, the positioning post 5 can be radially slidably installed within the mounting groove 311. In actual application, the positioning post 5 can generate a micron-level sliding displacement along the radial direction of the cutter body 1.

[0044] In practical applications, refer to Figure 2 Each positioning post 5 includes a base 511 and a cladding layer 512 covering the outer surface of the base 511. The base 511 is made of a manganese-copper based high-damping alloy. For example, the base 511 is made of M2052 alloy, which can convert the mechanical energy of vibration transmitted from the core 100 during processing into heat energy and dissipate it. The cladding layer 512 is made of a copper-based powder metallurgy material containing molybdenum disulfide, which has self-lubricating properties and provides boundary lubrication protection when the hydrodynamic fluid film ruptures, preventing cold welding seizing between the working surface of the positioning post 5 and the surface of the core 100. Furthermore, the thickness of the cladding layer 512 is 100 μm to 300 μm.

[0045] In actual implementation, the working surface of the positioning post 5 facing the outer cylindrical surface of the core 100 is an arc-shaped surface, and its radius of curvature matches the diameter of the core 100. (Reference) Figure 1At least one wedge-shaped groove 52 is formed on the working surface. The depth of the wedge-shaped groove 52 decreases along the direction of cutting fluid flow. Specifically, the inlet depth near the top surface 32 is 0.2 mm to 0.5 mm, and the outlet depth near the bottom surface of the groove 2 is 0 mm, i.e., flush with the working surface. Furthermore, the length of the wedge-shaped groove 52 is less than the axial length of the positioning pin 5.

[0046] In this embodiment, the static pressure cavity 61 is located between the bottom of the mounting groove 311 and the bottom of the positioning post 5.

[0047] In application, the static pressure chamber 61 is a cylindrical recess with a depth of 1mm to 2mm and a diameter less than or equal to the bottom dimension of the positioning post 5.

[0048] In practical applications, a static pressure channel 53 is provided inside the cutter body 1. One end of the static pressure channel 53 is connected to the static pressure chamber 61, and the other end of the static pressure channel 53 is connected to the second cutting fluid injection device.

[0049] In some embodiments, a static pressure channel 53 is provided on the back of the positioning post 5. The static pressure channel 53 is a slender channel that penetrates the positioning post 5. One end of the static pressure channel 53 is connected to the center of the bottom surface of the static pressure chamber 61, and the other end of the static pressure channel 53 is connected to the second cutting fluid injection device.

[0050] The input end of the second cutting fluid injection device is connected to the high-pressure cutting fluid supply source via a one-way valve, and the output end of the second cutting fluid injection device is connected to the static pressure channel 53. The one-way valve is configured to allow high-pressure cutting fluid to flow from the high-pressure cutting fluid supply source to the static pressure chamber 61, and to cut off flow in the reverse direction. The high-pressure cutting fluid supply source can be the outlet of the machine tool's main cutting fluid pump.

[0051] In actual implementation, the bottom dimension of the positioning post 5 is smaller than the top dimension. An O-ring seal 62 is fitted on the outer circumferential surface of the bottom of the positioning post 5. The seal 62 is interference-fitted with the inner wall of the static pressure chamber 61, sealing the static pressure chamber 61 into an independent pressure chamber. When high-pressure cutting fluid enters the static pressure chamber 61 through the static pressure channel 53, a uniform static pressure is established in the static pressure chamber 61 under the sealing action of the seal 62. The static pressure acts on the bottom of the positioning post 5, pushing the positioning post 5 to produce a slight displacement of 10μm to 30μm radially outward.

[0052] This embodiment includes three independent cutting fluid injection devices.

[0053] The nozzle of the first cutting fluid injection device is directed towards the working area of ​​the wedge-shaped groove 52 of the positioning post 5. During machining, the first cutting fluid injection device supplies cutting fluid to the wedge-shaped groove 52 to maintain the continuous formation of the hydrodynamic fluid film. The input end of the first cutting fluid injection device is equipped with an electro-hydraulic proportional valve, which can adjust the supply pressure according to the control signal and can superimpose periodic pressure to suppress cutting resonance.

[0054] The injection outlet of the second cutting fluid injection device is connected to the static pressure channel 53, which is used to supply high-pressure cutting fluid to the static pressure chamber 61 to realize the static pressure pre-support function during the shutdown phase.

[0055] The spray direction of the third cutting fluid injection device is parallel to the cutting edge of the cutting tool 43 and intersects with the extending direction of the chip removal hole 7 inlet. Specifically, the angle between the spray direction of the third cutting fluid injection device and the extending direction of the chip removal hole 7 inlet is 30° to 45°. Furthermore, an obstacle avoidance channel 312 is provided on the step to accommodate the spray jet of the third cutting fluid injection device, allowing the cutting fluid to reach the cutting area without obstruction and forcibly press the chips into the chip removal hole 7.

[0056] In this embodiment, the cutting blade 43 is installed on the bottom surface of the groove 2, that is, the area directly below the step.

[0057] In application, the cutting blade 43 is fixed in the cutting blade 43 slot of the blade body 1 by countersunk screws.

[0058] In practical applications, in the radial direction of the cutter body 1, the outermost radial point of the cutting edge of the cutting tool 43 is lower than the innermost radial point of the wedge groove 52 on the working surface of the positioning post 5. That is, the highest point of the cutting tool 43 is lower than the lowest point of the wedge groove 52, ensuring that the cutting tool 43 is completely located in the area below the gravity of the sleeve core 100. When cutting the sleeve core 100, the radial cutting force is opposite to the direction of the gravity of the sleeve core 100, using gravity to offset part of the cutting resistance, while avoiding spatial interference between the cutting edge and the wedge groove 52.

[0059] In this embodiment, the chip removal hole 7 passes through the connecting end 12 of the cutter body 1 along the axial direction and communicates with the outlet of the connecting end 12.

[0060] When in use, the inlet of the chip removal hole 7 is funnel-shaped and located directly below the cutting blade 43. The inlet diameter is larger than the width of the cutting blade 43 to ensure that the chips can fall in smoothly.

[0061] In practical applications, the inner wall of the chip removal hole 7 is provided with a check groove every 8mm to 12mm along the axial direction. Specifically, the cross-sectional shape of the check groove is wedge-shaped. The steep surface of the check groove faces the direction of discharge of cutting fluid and chips, that is, towards the connecting end 12; the sloping surface of the check groove faces the direction of flow of cutting fluid, that is, towards the working end 11.

[0062] Example 2: Based on Example 1, this example introduces a machining method for CNC machine tool cutting tools.

[0063] The machining method of the CNC machine tool in this embodiment is applicable to machining through holes in untreated blanks.

[0064] For details, please refer to Figure 5The machining method for CNC machine tool tools in this embodiment includes steps SS11 to SS12. Furthermore, the machining method in this embodiment also includes steps SS13 to SS14. Even further, during the driving of the machining tool feed, the machining method in this embodiment also includes a resonance suppression step.

[0065] Step SS11: Supply cutting fluid to the wedge groove 52.

[0066] In application, before starting the rotation of the machining tool, cutting fluid is supplied to the wedge-shaped groove 52 on the working surface of the positioning column 5 through the first cutting fluid injection device, so that the wedge-shaped groove 52 is filled with cutting fluid.

[0067] In practical applications, the groove 2 area is also filled with cutting fluid, providing a sufficient fluid source for the subsequent establishment of the hydrodynamic fluid film.

[0068] Step SS12: Start the machining cutter rotation. When the machining cutter speed reaches the preset speed, drive the machining cutter to feed axially. The first machining cutter 41 and the second machining cutter 42 machine an annular area on the workpiece and form a core 100. At the same time, the cutting fluid in the wedge groove 52 forms a hydrodynamic fluid film between the working surface of the positioning post 5 and the outer cylindrical surface of the core 100.

[0069] When in use, the machining tool is started to rotate, and the first machining tool 41 and the second machining tool 42 rotate together with the tool body 1.

[0070] In practical applications, the preset speed is determined based on the diameter of the core 100, the viscosity of the cutting fluid, and the geometric parameters of the wedge groove 52. Specifically, the preset speed is 30% to 50% of the average historical machining speed.

[0071] In actual implementation, when the machining tool reaches the preset speed, it is driven to feed axially. The first machining tool 41 and the second machining tool 42 machine an annular area on the workpiece blank and form a columnar core 100 at the center of the blank.

[0072] During this process, the outer cylindrical surface of the rotating sleeve core 100 drags the cutting fluid in the wedge groove 52 into the convergence gap. Because the depth of the wedge groove 52 decreases along the direction of cutting fluid flow, the fluid is compressed within the convergence channel, resulting in a decrease in flow velocity and a sharp increase in pressure. This forms a hydrodynamic fluid film with a thickness of 5μm to 20μm between the arc-shaped working surface of the positioning post 5 and the outer cylindrical surface of the sleeve core 100. This hydrodynamic fluid film completely physically isolates the positioning post 5 from the surface of the sleeve core 100, transforming the original solid sliding friction into fluid shear friction, thus achieving low-friction, wear-free, non-contact guiding support.

[0073] Before the machining tool reaches the preset speed, there may be slight boundary friction between the positioning post 5 and the surface of the core 100. However, since the axial feed has not yet started during the start-up phase, the radial load is extremely small, and the wedge groove 52 is already filled with cutting fluid, the brief contact between the positioning post 5 and the surface of the core 100 at this time will not damage the microstructure of the wedge groove 52.

[0074] Step SS13: During the machining process, cutting fluid is sprayed onto the cutting edge area of ​​the cutting tool 43 by the third cutting fluid injection device. The spraying direction is parallel to the cutting edge of the cutting tool 43 and intersects with the inlet extension direction of the chip removal hole 7.

[0075] In application, during the machining feed process, the third cutting fluid injection device continuously sprays cutting fluid into the cutting edge area of ​​the cutting tool 43. In actual application, the jet stream reaches the cutting area unimpeded through the clearance channel 312 opened on the step.

[0076] In actual implementation, the spray direction is parallel to the cutting edge of the cutting blade 43 and intersects with the extending direction of the chip discharge hole 7 inlet. On the one hand, it cools and lubricates the cutting edge of the cutting blade 43, and on the other hand, it generates a downward thrust, forcibly pressing the chips generated by cutting towards the chip discharge hole 7 inlet located directly below.

[0077] Step SS14: The chips generated by the cutting blade 43 cutting the core 100 are carried by the cutting fluid and discharged through the chip discharge hole 7.

[0078] In application, the cutting blade 43 continuously cuts off the core portion 100 of the sleeve at the bottom of the groove 2. Since the cutting blade 43 is installed eccentrically downward, the highest radial point of its cutting edge is lower than the lowest radial point of the wedge groove 52. After the core portion 100 is cut off, it falls naturally downward under the action of gravity. This, combined with the downward thrust generated by the third cutting fluid injection device, causes the chips to quickly detach from the cutting edge area and fall into the inlet of the chip discharge hole 7.

[0079] In practical applications, all chips generated by the cutting tool flow into the chip discharge hole 7 along with the cutting fluid.

[0080] In actual implementation, after the chips enter the chip removal hole 7, they are carried by the high-speed flowing cutting fluid and transported backward along the chip removal hole 7. During the chip removal process, the check groove on the inner wall of the chip removal hole 7 provides almost no resistance to the forward-flowing chips. However, when the cutting fluid pressure fluctuates, the local eddies in the check groove can effectively prevent the chips from retreating backward, ensuring the continuity and stability of chip removal.

[0081] The resonance suppression steps in this embodiment include steps SS15 to SS16.

[0082] Step SS15: Obtain the cutting torque frequency of the cutter 43 and the first-order bending natural frequency of the core 100.

[0083] In application, the cutting torque frequency of the cutting tool 43 can be obtained by extracting the AC component of the machine tool spindle motor torque command and performing spectrum analysis; the bending vibration characteristic frequency of the core 100 can be extracted based on the modal parameter identification algorithm by analyzing the transient response signal collected by the accelerometer installed on the back of the positioning column 5 during the feed pause.

[0084] Step SS16: When the ratio of the cutting torque frequency to the first-order bending natural frequency is within the preset resonance sensitive range, a periodic pressure is superimposed on the current pressure of the cutting fluid supplied to the wedge groove 52.

[0085] When applied, the preset resonance sensitivity range is 0.85 to 1.15. When the ratio of the cutting torque frequency of the cutter 43 to the first-order bending natural frequency of the core 100 is within the preset resonance sensitivity range, it indicates that the core 100 is at risk of regenerative chatter.

[0086] In practical applications, the driving electro-hydraulic proportional valve adds a periodic pressure to the current pressure of the cutting fluid supplied to the wedge groove 52. The frequency of the periodic pressure is 5Hz to 25Hz, and the amplitude is 5% to 10% of the current steady-state pressure. This can cause periodic fluctuations in the stiffness of the hydrodynamic fluid film, disrupting the phase-locked relationship between the cutting force and the bending mode of the sleeve core 100, forcing the sleeve core 100 to break away from the stable resonance state, and causing the vibration amplitude to decay rapidly.

[0087] In actual implementation, when the ratio of the cutting torque frequency of the cutter 43 to the first-order bending natural frequency of the core 100 is not in the preset resonance sensitive range, the periodic pressure is stopped to restore the cutting fluid pressure to a steady state value, thereby reducing energy consumption and minimizing disturbance to the chip discharge flow field.

[0088] Example 3: Based on Example 1, this example introduces a machining method for CNC machine tool cutting tools.

[0089] The CNC machine tool machining method of this embodiment is applicable to scenarios where the machine needs to be stopped and restarted midway through deep hole machining due to reasons such as changing the cutting tool, cleaning chips, or debugging the equipment.

[0090] Compared with Embodiment 2, this embodiment adds a static pressure pre-support protection step after mid-process shutdown, in order to avoid the wedge groove 52 being scratched and damaged when restarted due to the positioning post 5 re-establishing pre-pressure contact with the core 100 surface caused by the shutdown.

[0091] refer to Figure 6The machining method for CNC machine tool tools in this embodiment includes steps SS21 to SS23. Further, the machining method in this embodiment also includes steps SS24 to SS25. Even further, during the tool feed process, the machining method in this embodiment also includes a resonance suppression step.

[0092] Step SS21: High-pressure cutting fluid is introduced into the static pressure chamber 61 to push the positioning column 5 to move radially outward with static pressure.

[0093] In application, before restarting the machining tool rotation, high-pressure cutting fluid is first introduced into the static pressure chamber 61 through the second cutting fluid injection device. The high-pressure cutting fluid enters the static pressure chamber 61 through the static pressure channel 53, and a uniform static pressure is established in the static pressure chamber 61 under the sealing action of the sealing ring 62. The static pressure acts on the bottom of the positioning post 5, pushing the positioning post 5 to produce a slight displacement radially outward.

[0094] During this process, the supply pressure of the high-pressure cutting fluid can be determined based on the bottom surface area, weight, and installation preload of the positioning post 5. Specifically, the supply pressure of the high-pressure cutting fluid can be from 5 MPa to 15 MPa. Under the supply pressure of the high-pressure cutting fluid, the radial displacement of the positioning post 5 is controlled to be from 10 μm to 30 μm, which can eliminate the static preload contact stress re-established between the working surface of the positioning post 5 and the surface of the sleeve core 100 due to machine shutdown.

[0095] Step SS22: Supply cutting fluid to the wedge groove 52.

[0096] In this embodiment, step SS22 is the same as step SS11 described in embodiment 2. Cutting fluid is supplied to the wedge-shaped groove 52 on the working surface of the positioning post 5 through the first cutting fluid injection device, so that the wedge-shaped groove 52 is filled with cutting fluid. At this time, the positioning post 5 has been lifted by hydrostatic pressure, and the gap between the wedge-shaped groove 52 and the surface of the sleeve core 100 is also filled with the surrounding cutting fluid, forming a liquid isolation layer.

[0097] Step SS23: Start the machining cutter rotation. When the machining cutter speed reaches the preset speed, cut off the flow of high-pressure cutting fluid into the hydrostatic chamber 61 and drive the machining cutter to feed axially. The first machining cutter 41 and the second machining cutter 42 machine an annular area on the workpiece and form a core 100. At the same time, the cutting fluid in the wedge groove 52 forms a hydrodynamic fluid film between the working surface of the positioning post 5 and the outer cylindrical surface of the core 100.

[0098] In application, when the machining tool reaches the preset critical speed, the one-way valve or solenoid valve of the second cutting fluid injection device closes, cutting off the supply of high-pressure cutting fluid to the static pressure chamber 61. At the same time, the machining tool is driven to continue feeding axially, and the first machining tool 41 and the second machining tool 42 continue to machine the annular area on the workpiece and maintain the formation of the core 100.

[0099] In practical applications, simultaneously with the cutoff of the hydrostatic fluid supply, the rotating sleeve core 100 drags and squeezes the cutting fluid within the wedge groove 52, establishing a hydrodynamic fluid film within the convergence gap. Since the initial gap caused by the hydrostatic jacking is slightly larger than the hydrodynamic fluid film gap, at the instant the hydrodynamic fluid film is established, the positioning post 5 automatically retracts under dynamic pressure to adjust to a hydrodynamic equilibrium position of 5μm to 20μm, completing the switch from hydrostatic jacking to hydrodynamic support. Throughout the entire startup process, the working surface of the positioning post 5 and the surface of the sleeve core 100 are always filled with liquid medium, and the microstructure of the wedge groove 52 does not come into any metal contact with the sleeve core 100, thus receiving complete protection.

[0100] Step SS24: During the machining process, cutting fluid is sprayed onto the cutting edge area of ​​the cutting tool 43 through the third cutting fluid spraying device. The spraying direction is parallel to the cutting edge of the cutting tool 43 and intersects with the inlet extension direction of the chip removal hole 7.

[0101] Step SS24 in this embodiment is the same as step SS13 described in Embodiment 2, and will not be repeated here.

[0102] Step SS25: The chips generated by the cutting blade 43 cutting the core of the sleeve 100 are carried by the cutting fluid and discharged through the chip discharge hole 7.

[0103] Step SS25 in this embodiment is the same as step SS14 in embodiment 2, and will not be repeated here.

[0104] The resonance suppression steps in this embodiment are the same as those in Embodiment 2, and will not be repeated here.

[0105] It is worth noting that the processing method described in this embodiment also includes an active protection step performed before each planned shutdown.

[0106] The active protection steps include: before the deceleration command is issued, the second cutting fluid injection device is turned on in advance to resume the supply of high-pressure cutting fluid to the static pressure chamber 61, so that the positioning column 5 is lifted again before the hydrodynamic fluid film collapses due to the decrease in speed, so as to ensure that the working surface of the positioning column 5 and the surface of the sleeve core 100 are always kept in a liquid isolation state during the entire deceleration process, and to avoid the wedge groove 52 scraping and wearing during the shutdown stage.

[0107] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A CNC machine tool cutting tool, characterized in that, include: The blade body has a groove at its working end, the inner wall of the groove forms a step, and at least one mounting groove is provided on the side of the step. A first processing cutter and a second processing cutter, wherein the first processing cutter is disposed on the outer edge of the top surface of the step, and the second processing cutter is disposed on the inner edge of the top surface of the step; At least one positioning post is provided, which is radially slidably mounted in the mounting groove. The positioning post has at least one wedge-shaped groove on its working surface facing the core of the sleeve, and the depth of the wedge-shaped groove decreases along the direction of the cutting fluid flow. A static pressure chamber is located between the bottom of the mounting groove and the bottom of the positioning post, and is used to introduce high-pressure cutting fluid to push the positioning post to move radially outward; A sealing ring is fitted onto the outer circumferential surface of the bottom of the positioning post and is interference-fitted with the inner wall of the static pressure chamber. A first cutting fluid injection device, wherein the injection outlet of the first cutting fluid injection device points to the working area of ​​the positioning column where the wedge groove is located; The second cutting fluid injection device has its input end connected to the high-pressure cutting fluid supply source via a one-way valve, and its output end connected to the static pressure chamber via a static pressure channel.

2. The CNC machine tool cutting tool according to claim 1, characterized in that, The inlet depth of the wedge-shaped groove near the top surface is 0.2 mm to 0.5 mm, and the outlet depth near the bottom surface of the groove is 0 mm. The length of the wedge-shaped groove is less than the axial length of the positioning post.

3. The CNC machine tool cutting tool according to claim 1, characterized in that, The positioning post includes: The substrate is made of a manganese-copper based high-damping alloy; A coating layer covering the outer surface of the substrate, the coating layer being made of a copper-based powder metallurgy material containing molybdenum disulfide.

4. The CNC machine tool cutting tool according to claim 1, characterized in that, Also includes: A cutting blade is mounted at the bottom of the groove, and the highest radial point of the cutting blade is lower than the lowest radial point of the wedge-shaped groove; Chip removal hole, the chip removal hole is funnel-shaped, the inlet of the chip removal hole is located below the cutting blade, and the outlet of the chip removal hole extends to the connecting end of the blade body; An obstacle avoidance channel is provided on the step to accommodate the jet stream from the third cutting fluid injection device, allowing the jet stream to reach the cutting area of ​​the cutting blade.

5. A method for machining CNC machine tool cutting tools as described in any one of claims 1 to 4, characterized in that, include: Supply cutting fluid to the wedge-shaped groove; The machining tool is started to rotate. When the machining tool speed reaches the preset speed, the machining tool is driven to feed axially. The first machining tool and the second machining tool machine an annular area on the workpiece and form a core. At the same time, the cutting fluid in the wedge groove forms a hydrodynamic fluid film between the working surface of the positioning post and the outer cylindrical surface of the core.

6. A method for machining CNC machine tool cutting tools as described in any one of claims 1 to 4, characterized in that, When restarting the machine after a mid-process stop during deep hole machining, the following applies: High-pressure cutting fluid is introduced into the static pressure chamber to push the positioning column outward radially with static pressure; Supply cutting fluid to the wedge-shaped groove; The machining tool is started to rotate. When the machining tool speed reaches the preset speed, the high-pressure cutting fluid is cut off from the hydrostatic chamber and the machining tool is driven to feed axially. The first machining tool and the second machining tool machine an annular area on the workpiece and form a core. At the same time, the cutting fluid in the wedge groove forms a hydrodynamic fluid film between the working surface of the positioning post and the outer cylindrical surface of the core.

7. The machining method for CNC machine tool cutting tools according to claim 6, characterized in that, During the machining process, cutting fluid is sprayed onto the cutting edge area of ​​the cutting tool by a third cutting fluid injection device. The spraying direction is parallel to the cutting edge of the cutting tool and intersects with the inlet extension direction of the chip removal hole. The chips generated by the cutting blade cutting the core of the sleeve are carried by the cutting fluid and discharged through the chip removal hole.

8. The machining method for CNC machine tool cutting tools according to claim 6, characterized in that, The supply pressure of the high-pressure cutting fluid is 5 MPa to 15 MPa; The radial displacement generated by the static pressure pushing the positioning column is 10μm to 30μm.

9. The machining method for CNC machine tool cutting tools according to claim 6, characterized in that, The process of driving the machining tool to feed also includes a resonance suppression step: Obtain the cutting torque frequency of the cutter and the first-order bending natural frequency of the core material; When the ratio of the cutting torque frequency to the first-order bending natural frequency falls within a preset resonance sensitive range, a periodic pressure is superimposed on the current pressure of the cutting fluid supplied to the wedge groove; wherein the frequency of the periodic pressure is 5Hz to 25Hz and the amplitude is 5% to 10% of the current steady-state pressure.

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