Internal spraying type self-lubricating cutter suitable for liquid nitrogen cooling

Abstract

A first channel is formed in a cutter bar part, a heat insulation sleeve is arranged in the first channel, a heat insulation cavity is formed between the heat insulation sleeve and the inner peripheral wall of the first channel, and a second channel is formed in the heat insulation sleeve; a nozzle part and a self-lubricating blade are arranged on the cutter bar part; a third channel is formed in the nozzle part, the cutter bar part conveys the liquid nitrogen to the third channel, a spray hole communicated with the third channel is formed in the nozzle part, and the nozzle part sprays the liquid nitrogen to the front cutter face of the self-lubricating blade through the spray hole; the length of the liquid nitrogen jet flow keeping section is in direct proportion to the diameter of the spraying hole, and the liquid nitrogen jet flow length is controlled within the jet flow keeping section; the self-lubricating blade takes WC as a matrix, cubic boron nitride cBN as a reinforcing phase and molybdenum disulfide MoS2 as a lubricating phase; the second sub-heat-insulation sleeve is attached to the inner circumferential wall of the first channel in a sealed mode, and a heat-insulation cavity is formed between the first sub-heat-insulation sleeve and the inner circumferential wall of the first channel. The cooling efficiency and the lubricating performance of the cutter can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultralow-temperature cutting machining, and particularly to an internal spray type self-lubricating cutter suitable for liquid nitrogen cooling. BACKGROUND

[0002] In the field of high-end equipment such as aerospace, military industry and ocean engineering, core components are widely made of difficult-to-machine materials with excellent performance to meet the high performance requirements under extreme service environments, such as titanium alloy, high-temperature alloy, composite material and polymer material, etc. These difficult-to-machine materials have the characteristics of large cutting force and high cutting temperature, and are prone to produce poor machining quality and serious tool wear during cutting machining, which seriously limits the high-quality and efficient machining production of the materials and increases the machining cost.

[0003] The application of liquid nitrogen medium cooling can effectively improve the machining quality and efficiency of difficult-to-machine materials and is environmentally friendly and non-polluting. However, due to the poor wettability and weak lubricating ability of liquid nitrogen, its cutting performance and application range are limited. To further improve the liquid nitrogen cooling machining performance and expand the material application range, it is necessary to study the liquid nitrogen cooling machining lubrication enhancement technology.

[0004] The above information disclosed in the background section of this application is only intended to increase the understanding of the background of the present application, and therefore, it can include information known by those of ordinary skill in the art. SUMMARY

[0005] In view of the problems pointed out in the background, the present application provides an internal spray type self-lubricating cutter suitable for liquid nitrogen cooling, which solves the problem of insufficient lubrication during cutting machining in an ultralow-temperature environment and improves the cooling efficiency and lubricating performance of the cutter.

[0006] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0007] In some embodiments of the present application, an internal spray type self-lubricating cutter suitable for liquid nitrogen cooling is provided, which comprises:

[0008] A cutter bar part, which has a first channel formed therein, a heat insulation sleeve is arranged in the first channel, the heat insulation sleeve extends along the length direction of the first channel, a heat insulation cavity is formed between the heat insulation sleeve and the inner peripheral wall of the first channel, and a second channel for conveying liquid nitrogen is formed in the interior of the heat insulation sleeve;

[0009] A nozzle part, which is arranged on the cutter bar part and has a third channel for conveying liquid nitrogen formed therein, the cutter bar part conveys liquid nitrogen to the third channel, and a spray hole communicating with the third channel is arranged on the nozzle part;

[0010] A self-lubricating blade is arranged on the tool bar part, and the nozzle part is configured to spray liquid nitrogen onto the rake face of the self-lubricating blade through the spray hole.

[0011] wherein,

[0012] S p is the length of the jet retention section of the liquid nitrogen, ρ0 is the initial density of the jet, ρ l is the density of the liquid nitrogen, ρ g is the density of nitrogen, α is the volume fraction of the liquid nitrogen, d0 is the diameter of the spray hole, C is the expansion coefficient, and the actual spraying distance of the liquid nitrogen is ≤S p .

[0013] The length of the jet of the liquid nitrogen is proportional to the diameter of the spray hole, and the length of the jet of the liquid nitrogen is controlled within the jet retention section.

[0014] The self-lubricating blade has a WC base, a cubic boron nitride cBN reinforcing phase, and a molybdenum disulfide MoS2 lubricating phase, and the volume fractions of the material raw materials of the self-lubricating blade are respectively WC: 60-70 vol%, cBN: 20 vol%, and MoS2: 10-20 vol%.

[0015] In some embodiments of the present application, the third channel includes a third channel first section and a third channel second section, the third channel first section is in communication with the liquid nitrogen conveying channel in the tool bar part, the third channel second section is in communication with the spray hole, and the included angle between the third channel first section and the third channel second section is an obtuse angle.

[0016] In some embodiments of the present application, the heat insulation sleeve includes a first sub-heat insulation sleeve and a second sub-heat insulation sleeve, two ends of the first sub-heat insulation sleeve are respectively provided with the second sub-heat insulation sleeve, the outer diameter of the second sub-heat insulation sleeve is greater than that of the first sub-heat insulation sleeve, the second sub-heat insulation sleeve is sealingly attached to the inner circumferential wall of the first channel, and the first sub-heat insulation sleeve and the inner circumferential wall of the first channel form the heat insulation cavity.

[0017] In some embodiments of the present application, the average size of the WC powder used in the self-lubricating blade is 0.2 μm, the purity is >99.95%, the average size of the cBN powder is 5-10 μm, the purity is >99.95%, and the average size of the MoS2 powder is 1-2 μm, the purity is >99.9%.

[0018] In some embodiments of the present application, the material of the heat insulation sleeve is modified polyimide, and the thermal conductivity coefficient is less than 0.15 W / (m·K).

[0019] In some embodiments of the present application, the material of the tool bar part is 40Cr, and the hardness is HRC32-36.

[0020] In some embodiments of the present application, the tool bar part comprises a first tool bar part section and a second tool bar part section, an included angle between the first tool bar part section and the second tool bar part section is obtuse, the first channel is formed in the first tool bar part section, the nozzle part is arranged on an outer portion of the second tool bar part section, and the self-lubricating blade is arranged on an end portion of the second tool bar part section.

[0021] In some embodiments of the present application, an insertion part is arranged on the nozzle part, an insertion hole is arranged on the first tool bar part section at a position close to the second tool bar part section, and the insertion part is inserted into the insertion hole to communicate the first channel with the third channel.

[0022] In some embodiments of the present application, an installation opening is arranged on an end portion of the first tool bar part section, and a liquid nitrogen supply device is connected to the installation opening through an adapter.

[0023] Compared with the prior art, the present application has the following advantages and positive effects:

[0024] The disclosed internal spraying type self-lubricating cutting tool adopts a liquid nitrogen internal spraying type cooling mode to improve the cooling efficiency of liquid nitrogen, and develops a self-lubricating blade suitable for an ultralow-temperature environment, which can ensure high-efficiency cooling of liquid nitrogen and at the same time endow the liquid nitrogen cooling tool with good lubricating performance, thereby effectively improving the cutting performance of liquid nitrogen cooling machining.

[0025] Other features and advantages of the present application will become more apparent after reading the specific embodiments of the present application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0027] Figure 1 A structural diagram of an internal spraying type self-lubricating cutting tool according to some embodiments;

[0028] Figure 2 A sectional view of an internal spraying type self-lubricating cutting tool according to some embodiments;

[0029] Figure 3 A structural diagram of a tool bar part according to some embodiments;

[0030] Figure 4 A structural diagram of a nozzle part according to some embodiments;

[0031] Figure 5 A structural diagram of the heat insulation sleeve according to some embodiments.

[0032] Reference signs:

[0033] 100, tool bar part; 110, first channel; 120, heat insulation sleeve; 121, second channel; 122, first sub heat insulation sleeve; 123, second sub heat insulation sleeve; 130, mounting port; 141, tool bar part first section; 142, tool bar part second section; 150, insertion hole;

[0034] 200, nozzle part; 210, third channel; 211, third channel first section; 212, third channel second section; 220, injection hole; 230, insertion part;

[0035] 300, self-lubricating blade;

[0036] 410, first screw; 420, second screw. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0038] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present application.

[0039] The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0040] In the description of the present application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "under", "below" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0042] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and arrangements of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0043] In some embodiments of the present application, a kind of internal spray type self-lubricating cutter suitable for liquid nitrogen cooling is provided, Figure 1 It is a structural diagram of the internal spray type self-lubricating cutter, Figure 2 It is an exploded view of the internal spray type self-lubricating cutter.

[0044] The internal spray type self-lubricating cutter includes a tool bar part 100. Figure 3 It is a structural diagram of the tool bar part 100, in order to embody the internal structure of the tool bar part 100, Figure 3 It is a perspective view. The inside of the tool bar part 100 is formed with a first channel 110, and the first channel 110 extends along the length direction of the tool bar part 100.

[0045] A heat insulation sleeve 120 is arranged in the first channel 110, Figure 5A structure diagram of the heat insulation sleeve 120. The heat insulation sleeve 120 extends along the length direction of the first channel 110. A heat insulation cavity is formed between the heat insulation sleeve 120 and the inner circumferential wall of the first channel 110. The heat insulation cavity changes the heat transfer form to reduce heat loss. The inside of the heat insulation sleeve 120 is formed with a second channel 121 for conveying liquid nitrogen.

[0046] The inner jetting self-lubricating cutting tool further comprises a nozzle part 200. Figure 4 A result diagram of the nozzle part 200, in order to reflect the internal structure of the nozzle part 200, Figure 4 A perspective view. The nozzle part 200 is arranged on the tool bar part 100, for example, the nozzle part 200 is arranged on the outside of the tool bar part 100. The inside of the nozzle part 200 is formed with a third channel 210 for conveying liquid nitrogen. The tool bar part 100 conveys liquid nitrogen to the third channel 210. The nozzle part 200 is provided with a jet hole 220 in communication with the third channel 210.

[0047] The inner jetting self-lubricating cutting tool further comprises a self-lubricating cutting blade 300. The self-lubricating cutting blade 300 is arranged on the tool bar part 100, and the nozzle part 200 is configured to jet liquid nitrogen to the rake face of the self-lubricating cutting blade 300 through the jet hole 220.

[0048] wherein,

[0049] S p is the jetting distance of the liquid nitrogen, ρ0 is the initial density of the jet, ρ l is the density of the liquid nitrogen, ρ g is the density of nitrogen, α is the volume fraction of the liquid nitrogen, d0 is the diameter of the jet hole 220, C is the expansion coefficient, and the actual jetting distance of the liquid nitrogen ≤ S p . The jetting length of the liquid nitrogen is controlled within the jetting maintaining section.

[0050] In a specific embodiment, the diameter of the jet hole 220 is 2 mm, and the jetting distance is 15 mm.

[0051] The self-lubricating cutting blade 300 takes WC as the matrix, cubic boron nitride cBN as the reinforcing phase, and molybdenum disulfide MoS2 as the lubricating phase. The volume fractions of the material raw materials of the self-lubricating cutting blade 300 are respectively WC: 60-70 vol%, cBN: 20 vol%, and MoS2: 10-20 vol%. The self-lubricating cutting blade 300 has good lubricating performance in an ultra-low temperature environment by reasonably configuring the proportions of each component.

[0052] In use, the external liquid nitrogen supply device delivers liquid nitrogen into the tool bar portion 100, the liquid nitrogen flows along the second channel 121, the liquid nitrogen in the tool bar portion 100 flows into the third channel 210 in the nozzle portion 200, the liquid nitrogen in the third channel 210 is sprayed onto the rake face of the self-lubricating blade 300 through the spray hole 220, and then chip machining is performed.

[0053] The tool in the present application adopts the liquid nitrogen internal spraying cooling mode, improves the cooling efficiency of liquid nitrogen, and develops the self-lubricating blade 300 suitable for the ultra-low temperature environment, so as to improve the cutting performance of the liquid nitrogen cooling machining while ensuring the high efficiency cooling of liquid nitrogen.

[0054] In some embodiments of the present application, the average size of the WC powder used in the self-lubricating blade 300 is 0.2 μm, the purity is > 99.95%, the average size of the cBN powder is 5-10 μm, the purity is > 99.95%, and the average size of the MoS2 powder is 1-2 μm, the purity is > 99.9%.

[0055] By optimizing the size and purity of each component of the self-lubricating blade 300, the lubricating performance of the blade is further improved.

[0056] In some embodiments of the present application, with reference to Figure 4 , the third channel 210 includes a third channel first section 211 and a third channel second section 212 in communication, the third channel first section 211 is in communication with the liquid nitrogen delivery channel in the tool bar portion 100, the third channel second section 212 is in communication with the spray hole 220, and the included angle between the third channel first section 211 and the third channel second section 212 is obtuse, so as to reduce the influence of the secondary flow at the elbow on the vaporization degree of liquid nitrogen, reduce the cavitation degree of liquid nitrogen, and improve the cooling efficiency.

[0057] In a specific embodiment, the included angle between the third channel first section 211 and the third channel second section 212 is 150°.

[0058] In some embodiments of the present application, with reference to Figure 5 , the heat insulation sleeve 120 includes a first sub-heat insulation sleeve 122 and a second sub-heat insulation sleeve 123 in an integrated structure, the two ends of the first sub-heat insulation sleeve 122 are respectively provided with the second sub-heat insulation sleeve 123, and the outer diameter of the second sub-heat insulation sleeve 123 is greater than the outer diameter of the first sub-heat insulation sleeve 122. The second sub-heat insulation sleeve 123 is sealingly attached to the inner circumferential wall of the first channel 110, and a heat insulation cavity is formed between the first sub-heat insulation sleeve 122 and the inner circumferential wall of the first channel 110.

[0059] The heat insulation sleeve 120 is provided in a "dumbbell type" structure, the sealing attachment between the second sub-heat insulation sleeve 123 and the inner circumferential wall of the first channel 110 realizes the sealing of the heat insulation cavity, and prevents the liquid nitrogen in the first channel 110 from entering the heat insulation cavity.

[0060] In some embodiments of the present application, the first sub-insulation sleeve 122 has a wall thickness of 1 mm, and the second sub-insulation sleeve 123 has a wall thickness of 2 mm.

[0061] In some embodiments of the present application, the material of the insulation sleeve 120 is a certain type of modified polyimide, and the thermal conductivity is less than 0.15 W / (m·K), which improves the insulation effect.

[0062] In some embodiments of the present application, the material of the cutter bar part 100 is 40Cr, and the hardness is HRC32-36.

[0063] In some embodiments of the present application, the cutter bar part 100 includes a one-piece cutter bar part first section 141 and a cutter bar part second section 142. The length of the cutter bar part first section 141 is greater than the length of the cutter bar part second section 142. The included angle between the cutter bar part first section 141 and the cutter bar part second section 142 is obtuse. The first channel 110 is formed in the cutter bar part first section 141. The nozzle part 200 is arranged on the outside of the cutter bar part second section 142. The self-lubricating blade 300 is arranged on the end of the cutter bar part second section 142.

[0064] The cutter bar part 100 has a bent structure, and the self-lubricating blade 300 is arranged on the bent end of the cutter bar part 100, which can avoid interference between the cutter bar part 100 and the workpiece to be cut.

[0065] In some embodiments of the present application, the nozzle part 200 is fixedly installed on the cutter bar part second section 142 by the first screw 410, which realizes the detachability and replaceability of the nozzle part 200.

[0066] In some embodiments of the present application, the self-lubricating blade 300 is fixedly installed on the end of the cutter bar part second section 142 by the second screw 420, which realizes the detachability and replaceability of the self-lubricating blade 300.

[0067] In some embodiments of the present application, the nozzle part 200 is provided with an insertion part 230, and the cutter bar part first section 141 is provided with a insertion hole 150 at a position close to the cutter bar part second section 142. The insertion part 230 is inserted into the insertion hole 150 to communicate the first channel 110 with the third channel 210. A sealing ring is arranged at the insertion position to prevent the leakage of liquid nitrogen.

[0068] A part of the first channel 110 extends out of the insulation sleeve 120, and a channel for the flow of liquid nitrogen is arranged in the insertion part 230. The channel communicates the first channel 110 with the third channel 210. Liquid nitrogen flows along the second channel 121 and then flows into the third channel 210 through the first channel 110. By communicating the first channel 110 with the third channel 210, it is not necessary to arrange an opening on the wall of the insulation sleeve 120 for the flow of liquid nitrogen into the nozzle part 200, which simplifies the processing of the insulation sleeve 120.

[0069] In some embodiments of the present application, the end of the blade bar section 141 is provided with a mounting port 130, and the liquid nitrogen supply device is connected to the mounting port 130 through an adapter, facilitating the installation of the liquid nitrogen supply device.

[0070] In some embodiments of the present application, the first channel 110 is located at the center of the blade bar 100, and the inner diameter of the first channel 110 is 8 mm.

[0071] The present application studies the quantitative relationship between the hole diameter of the liquid nitrogen injection hole and the cooling distance, and the length of the jet retention section is in a positive relationship with the liquid nitrogen injection hole diameter. Controlling the jet length within the retention section can achieve better cooling efficiency. When ρ m = ρ0, S p takes the minimum value. During the injection process, due to cavitation and heat transfer, the actual injected liquid nitrogen is a two-phase flow, and the retention section length value will be greater than the minimum value of S p . Therefore, the injection distance should be less than the minimum value of S p to meet the requirement of suppressing the attenuation of liquid nitrogen jet cooling efficiency.

[0072] The present application analyzes the influence of nozzle structure on the jet. To study the influence of different nozzle structures on the jet state, four different structures of nozzles, i.e. straight nozzle, conical contraction nozzle, circular arc contraction nozzle and outward expansion nozzle, are designed for comparative analysis. It is found that the outward expansion nozzle has a faster speed decay and a shorter retention section, and there is no significant difference in the length of the retention section between the straight nozzle, the conical contraction nozzle and the circular arc contraction nozzle. The conical contraction nozzle and the circular arc contraction nozzle have an ascending process at the beginning of the jet, while the straight nozzle and the outward expansion nozzle do not have this feature, which is speculated to be caused by the contraction structure, but the length of the retention section has no significant difference with the straight nozzle. Among the four structures of nozzles, the outward expansion nozzle has the fastest temperature decay rate. Although the conical contraction nozzle and the circular arc contraction nozzle have an ascending process in the speed distribution, it does not affect the temperature distribution of the jet. The speed and temperature of the straight nozzle are relatively stable in the retention section, and there is no obvious mutation phenomenon. Considering the speed and temperature distribution law of the four nozzles and the feasibility of the actual manufacturing process, compared with the other three structures of nozzles, the straight nozzle has obvious advantages, therefore the nozzle of the present application adopts the straight nozzle structure.

[0073] The application also optimizes the angle of the outlet elbow. In the manufacturing process of the tool, in order to ensure the accuracy of the jet position, the transmission channel inevitably has an elbow structure at the outlet. Since the pressure of liquid nitrogen in the channel of the tool is relatively large, there is a large pressure jump after the jet compared with the atmospheric pressure at the outlet. The pressure difference between the inside and outside of the jet outlet causes cavitation effect of liquid nitrogen at the outlet elbow, which affects the jet velocity and the volume fraction of liquid nitrogen. By analyzing the velocity, the volume fraction and the temperature of liquid nitrogen at different elbow angles, it is found that the elbow angle has little effect on the temperature of the fluid. With the increase of the elbow angle, the velocity and the volume fraction of liquid nitrogen at the outlet increase in a nearly linear trend. The influence of the elbow angle on the volume fraction of liquid nitrogen is the most serious, and the maximum difference is more than 20%, which indicates that when the elbow angle is increased, the influence of the secondary flow and cavitation effect on liquid nitrogen can be effectively reduced. According to the above analysis results, in order to maintain a high initial velocity and volume fraction of liquid nitrogen, the elbow at the outlet of the tool for liquid nitrogen jet should be as obtuse as possible to reduce the influence on the velocity and the volume fraction of liquid nitrogen.

[0074] The application studies the heat insulation method of the main transmission channel. In order to prevent vaporization, a vacuum pipe needs to be used in the process of transmitting liquid nitrogen from the supply device to the tool. The vacuum pipe is thicker than the ordinary pipe and has a larger bending resistance. In order to avoid interference with machine parts during use of the tool, or even break the adapter, the liquid nitrogen inlet of the tool is arranged at the tail of the tool shank, which increases the length of the transmission path of liquid nitrogen and intensifies the heat exchange between liquid nitrogen and the wall during the transmission process in the tool body. At this time, the liquid nitrogen enters a uniformly heated channel, and if the heat input through the wall from the outside is sufficient, even saturation boiling will occur, which will cause the dryness to continuously increase, and the flow pattern of the liquid will change from bubble flow, annular flow, mist flow to one-way gas in turn. Therefore, the only way to reduce the external heat input is to increase the equivalent thermal resistance of the cylinder wall. Installing heat insulation materials in the cylinder wall is an effective way to increase the equivalent thermal resistance of the cylinder wall. It is found through research that simply increasing the wall thickness has limited effect on improving the heat insulation performance, and because of the size limitation of the tool channel, the thickness of the heat insulation sleeve will be too large to reduce the liquid nitrogen flow space, so simply increasing the thickness of the heat insulation sleeve is not feasible, and therefore the method of reducing the heat transfer area is adopted to improve the heat insulation capacity of the heat insulation sleeve. By digging grooves on the surface of the heat insulation sleeve, a "dumbbell" structure is formed, a cavity is manufactured between the inner surface of the tool body and the outer surface of the heat insulation sleeve, the heat transfer mode is changed, and the heat conduction efficiency is reduced.

[0075] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0076] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An internally sprayed self-lubricating cutting tool suitable for liquid nitrogen cooling, characterized in that, Including: The tool holder has a first channel inside, which extends along the length of the tool holder. A heat insulation sleeve is provided inside the first channel, which extends along the length of the first channel. A heat insulation cavity is formed between the heat insulation sleeve and the inner peripheral wall of the first channel. A second channel for conveying liquid nitrogen is formed inside the heat insulation sleeve. A nozzle section is disposed on the cutter bar section, and a third channel for conveying liquid nitrogen is formed inside it. The cutter bar section conveys liquid nitrogen to the third channel, and the nozzle section is provided with a spray hole communicating with the third channel. A self-lubricating insert is provided on the tool holder, and the nozzle is configured to spray liquid nitrogen onto the rake face of the self-lubricating insert through the spray hole; in, S p ρ is the length of the liquid nitrogen jet holding section, ρ0 is the initial jet density, and ρ l ρ is the density of liquid nitrogen. g Let α be the density of nitrogen gas, d0 be the volume fraction of liquid nitrogen, C be the diameter of the nozzle, and S be the expansion coefficient. The actual injection distance of liquid nitrogen is ≤ S. p ; The length of the liquid nitrogen jet holding section is directly proportional to the diameter of the nozzle, and the jet length of the liquid nitrogen is controlled within the jet holding section; The self-lubricating blade uses WC as the matrix, cubic boron nitride (cBN) as the reinforcing phase, and molybdenum disulfide (MoS2) as the lubricating phase. The volume fractions of the raw materials for the self-lubricating blade are WC: 60-70 vol%, cBN: 20 vol%, and MoS2: 10-20 vol%. The heat insulation sleeve includes a first sub-heat insulation sleeve and a second sub-heat insulation sleeve. The second sub-heat insulation sleeve is respectively provided at both ends of the first sub-heat insulation sleeve. The outer diameter of the second sub-heat insulation sleeve is larger than the outer diameter of the first sub-heat insulation sleeve. The second sub-heat insulation sleeve is sealed and abuts against the inner peripheral wall of the first channel. The heat insulation cavity is formed between the first sub-heat insulation sleeve and the inner peripheral wall of the first channel.

2. The cutting tool according to claim 1, characterized in that, The third channel includes a third channel section 1 and a third channel section 2. The third channel section 1 is connected to the liquid nitrogen delivery channel in the cutter bar, and the third channel section 2 is connected to the nozzle. The included angle between the third channel section 1 and the third channel section 2 is an obtuse angle.

3. The cutting tool according to claim 1, characterized in that, The self-lubricating blade uses WC powder with an average size of 0.2 μm and a purity of >99.95%, cBN powder with an average size of 5-10 μm and a purity of >99.95%, and MoS2 powder with an average size of 1-2 μm and a purity of >99.9%.

4. The cutting tool according to claim 1, characterized in that, The insulation sleeve is made of modified polyimide with a thermal conductivity of less than 0.15 W / (m·K).

5. The cutting tool according to claim 1, characterized in that, The material of the tool holder is 40Cr, with a hardness of HRC32-36.

6. The cutting tool according to any one of claims 1 to 5, characterized in that, The blade holder includes a first blade holder section and a second blade holder section. The included angle between the first blade holder section and the second blade holder section is an obtuse angle. The first blade holder section has a first channel formed inside. The nozzle section is provided on the outside of the second blade holder section. The self-lubricating blade is provided at the end of the second blade holder section.

7. The cutting tool according to claim 6, characterized in that, The nozzle is provided with an insertion part, and a hole is provided on one section of the blade rod near the second section of the blade rod. The insertion part is inserted into the hole to connect the first channel and the third channel.

8. The cutting tool according to claim 6, characterized in that, The end of one section of the cutter bar is provided with a mounting port, and the liquid nitrogen supply device is connected to the mounting port via an adapter.

Images