Milling cutter coating structure and preparation method for high-speed machining of high-strength die steel

Abstract

The application discloses a kind of milling cutter coating structure and preparation method for high-strength die steel high-speed processing, including milling cutter matrix, primer layer, intermediate layer and top layer, the outside of milling cutter matrix is equipped with primer layer, the outside of primer layer is equipped with intermediate layer, the outside of intermediate layer is equipped with top layer, the primer layer is AlCrN layer, top layer is AlCrN+TiCrAlSiYN mixed layer, intermediate layer includes multiple periodic cycle layers arranged from inside to outside layer, each periodic cycle layer includes AlCrN unit layer and AlCrN+TiCrAlSiYN mixed unit layer, AlCrN unit layer in any one periodic cycle layer is arranged below AlCrN+TiCrAlSiYN mixed unit layer, the thickness ratio of AlCrN unit layer and AlCrN+TiCrAlSiYN mixed unit layer in each periodic cycle layer is 1:1-3:1, and the intermediate layer includes 10-24 periodic cycle layers;The application can improve the hardness and high-temperature resistance of ball nose milling cutter, improve the wear condition of milling cutter in the machining process, and improve the processing quality.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing tools, and particularly relates to a milling cutter coating structure and a preparation method for high-speed processing of high-strength die steel. Background Art

[0002] In recent years, mold manufacturing technology with high-speed milling as its research direction has been widely used in the mold shaping processing of automotive and aerospace parts. In the milling processing of many cavity molds and complex free-form surface contour parts, the advantages of high-speed milling with ball-end milling cutters, characterized by high material removal rate, one-step forming, and multi-degree-of-freedom milling feed, are becoming increasingly obvious. Since high-strength steel and ultra-high-strength steel have effectively achieved lightweighting of vehicles and improved the collision resistance and safety performance of vehicles, they have become an important development direction for automotive steel. High-strength mold steel will be subjected to considerable compressive stress and friction during milling, and will also generate cutting heat. For existing ball-end milling cutters, milling under such harsh conditions will accelerate the wear and fatigue failure time of the milling cutter, shorten the service life of the ball-end milling cutter, and reduce the milling quality of the milling cutter, which ultimately affects the processing quality and processing accuracy of high-strength mold steel workpieces. Summary of the Invention

[0003] In response to the wear and failure of ball-end milling cutters during high-speed milling of mold steel, the present invention provides a milling cutter coating structure and preparation method for high-speed machining of high-strength mold steel, which can improve the wear of the tool during high-speed machining and improve the machining quality.

[0004] The technical solution of the present invention is as follows: a milling cutter coating structure for high-speed processing of high-strength mold steel includes a milling cutter base, a base layer, an intermediate layer and a top layer, a base layer is provided on the outside of the milling cutter base, an intermediate layer is provided on the outside of the base layer, and a top layer is provided on the outside of the intermediate layer, the base layer is an AlCrN layer, the top layer is an AlCrN+TiCrAlSiYN mixed layer, the intermediate layer includes a plurality of periodic circulation layers arranged from the inside to the outside, each periodic circulation layer includes an AlCrN unit layer and an AlCrN+TiCrAlSiYN mixed unit layer, the AlCrN unit layer in any periodic circulation layer is arranged below the AlCrN+TiCrAlSiYN mixed unit layer, the thickness ratio of the AlCrN unit layer and the AlCrN+TiCrAlSiYN mixed unit layer in each periodic circulation layer is in the range of 1:1-3:1, and the intermediate layer includes 10-24 periodic circulation layers.

[0005] The method for preparing a milling cutter coating structure for high-speed machining of high-strength die steel comprises the following steps:

[0006] Step 1: Clean the milling cutter to be processed through spraying → ultrasonic → rough cleaning → rinsing → ultrasonic fine cleaning → rinsing → ultrasonic rinsing → pure water rinsing → dewatering → drying process;

[0007] Step 2: Clamp the cleaned milling cutter onto the turret to achieve three-dimensional rotation. Load Ti target, AlCr target and TiCrAlSiY target into the coating furnace, push the turret into the furnace and close the furnace door.

[0008] Step 3: Vacuum and heat the coating furnace to a vacuum degree of 4×10 -3 Pa, heating temperature to 450-500℃;

[0009] Step 4: Clean the milling cutter with Ar+. Introduce Ar into the furnace, adjust the rotating frame speed to 2 r / min, energize the tungsten filament to ionize the Ar to form a glow ion beam, maintain the temperature at 450-500℃, connect the rotating frame and milling cutter to a high bias voltage of -200--400V, and let the high energy of Ar+ impact the milling cutter surface to remove the impurities remaining on the milling cutter surface and ensure the cleanliness of the milling cutter surface.

[0010] Step 5: Perform Ti+ etching on the milling cutter, disconnect the tungsten filament power supply, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, continue to introduce Ar, power the Ti target assembly, the current is 50-120A, adjust the bias voltage to -200--1000V, and the etching time is 10-30min;

[0011] Step 6: Perform AlCrN base coating operation, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, turn off Ar, introduce appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0 Pa, turn off the power supply of the Ti target group, turn on the power supply of the AlCr target group, the target current is 80-200A, and the bias adopts a gradient process. After stabilizing at -70V for 5-10min, it is gradually increased to -100--200V in 5-10min.

[0012] Step 7: Perform multiple cycle layer coating operations, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3r / min, introduce an appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0Pa, keep the AlCr target group power on, the target current is 80-200A, and the bias voltage is adjusted to -100-200V; after 2-6 minutes, turn on the TiCrAlSiY target group power supply to make the two groups of targets work simultaneously, the TiCrAlSiY target current is 80-200A, the bias voltage is adjusted to -100-200V, and the TiCrAlSiY target group power supply is turned off after 1-3 minutes. At this point, a cycle layer of AlCrN / AlCrN+TiCrAlSiYN is completed, and this process is continued for 10-24 times;

[0013] Step 8: Perform AlCrN+TiCrAlSiYN top coating operation, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, introduce appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0Pa, and turn on the power supply of AlCr and TiCrAlSiY target groups at the same time. The target current is 80-200A, and the bias voltage is adjusted to -100--200V. After 2-5 minutes, turn off the power supply of AlCr and TiCrAlSiY target groups;

[0014] Step 9: The coating operation is carried out, and the furnace is cooled by introducing N2 into the furnace. When the temperature in the coating furnace chamber cools down to below 200°C, the furnace door is opened and the milling cutter is taken out after continuing to cool down to below 50°C.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1) the addition of Si element in the top and middle layers of AlCrN+TiCrAlSiYN improves the hardness of the coating while maintaining good wear resistance; 2) the addition of rare earth element Y can significantly improve the high-temperature resistance of the coating and enhance the red hardness of the tool, especially in the milling process using coolant, when the tool is subjected to alternating hot and cold stress, it can effectively reduce the phenomenon of material sticking on the tool surface and increase the service life of the tool; 3) the AlCrN base layer adopts a gradient bias process, which can improve the bonding strength between the coating and the milling cutter substrate; 4) the periodic nano-composite structure of AlCrN and TiCrAlSiYN can effectively reduce the internal stress of the coating and effectively prevent the tendency of longitudinal cracks in the coating to expand. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The interlayer structure diagram of the invented milling cutter coating structure;

[0017] The figure is marked: 1. top layer, 2. middle layer, 21. periodic cycle layer, 21a. AlCrN unit layer, 21b. AlCrN+TiCrAlSiYN mixed unit layer, 3. primer layer, 4. milling cutter base. DETAILED DESCRIPTION

[0018] The application will be further described below in combination with the drawings and examples.

[0019] As Figure 1 The milling cutter coating structure for high-strength die steel high-speed machining of the application is shown in the figure, which comprises a milling cutter base 4, a primer layer 3, a middle layer 2 and a top layer 1. The outer side of the milling cutter base 4 is provided with the primer layer 3, the outer side of the primer layer 3 is provided with the middle layer 2, and the outer side of the middle layer 2 is provided with the top layer 1. The primer layer 3 is an AlCrN layer, the top layer is an AlCrN+TiCrAlSiYN mixed layer, and the middle layer 2 comprises a plurality of periodic cycle layers 21 arranged from the inside to the outside layer by layer. Each periodic cycle layer 21 comprises an AlCrN unit layer 21a and an AlCrN+TiCrAlSiYN mixed unit layer 21b. The AlCrN unit layer 21a in any one periodic cycle layer 21 is arranged below the AlCrN+TiCrAlSiYN mixed unit layer 21b. The thickness ratio of the AlCrN unit layer 21a to the AlCrN+TiCrAlSiYN mixed unit layer 21b in each periodic cycle layer 21 ranges from 1:1 to 3:1. The middle layer comprises 10-24 periodic cycle layers.

[0020] The AlCrN (chromium aluminum nitride) coating has excellent thermal stability and corrosion resistance, has the advantages of high hardness, high wear resistance, high temperature resistance, low friction coefficient, etc., and the maximum heat resistance temperature can reach 1000℃, and the hardness of the coating is also improved, which can reach 3500HV at the highest, and is particularly suitable for high-speed cutting and high-hardness cutting. In the above scheme, the AlCrN coating serves as the primer layer, and the primer layer in each periodic cycle layer can ensure that the entire coating has very high machining stability.

[0021] On this basis, the mixed layer of AlCrN+TiCrAlSiYN is alternately arranged outside each AlCrN layer. The mixed layer is a coating mixed with TiCrAlSiYN on the basis of AlCrN. In addition to the characteristics of the AlCrN layer, the addition of Si element improves the hardness of the coating, and at the same time, the coating maintains good wear resistance. The addition of rare earth element Y can significantly improve the high-temperature resistance of the coating and improve the red hardness of the tool. Especially in the milling process using cooling liquid, under the condition that the tool bears alternating cold and hot stress, the phenomenon of tool surface sticking can be effectively reduced, and the service life of the tool is improved.

[0022] Moreover, in each cycle layer, the periodic composite structure of AlCrN+TiCrAlSiYN can effectively reduce the internal stress of the coating and effectively prevent the longitudinal crack propagation trend of the coating.

[0023] The method for preparing a milling cutter coating structure for high-speed machining of high-strength die steel comprises the following steps:

[0024] Step 1: Clean the milling cutter to be processed through spraying → ultrasonic → rough cleaning → rinsing → ultrasonic fine cleaning → rinsing → ultrasonic rinsing → pure water rinsing → dewatering → drying process;

[0025] Step 2: Clamp the cleaned milling cutter onto the turret to achieve three-dimensional rotation. Load Ti target, AlCr target and TiCrAlSiY target into the coating furnace, push the turret into the furnace and close the furnace door.

[0026] Step 3: Vacuum and heat the coating furnace to a vacuum degree of 4×10 -3 Pa, heating temperature to 450-500℃;

[0027] Step 4: Clean the milling cutter with Ar+. Introduce Ar into the furnace, adjust the rotating frame speed to 2 r / min, energize the tungsten filament to ionize the Ar to form a glow ion beam, maintain the temperature at 450-500℃, connect the rotating frame and milling cutter to a high bias voltage of -200--400V, and let the high energy of Ar+ impact the milling cutter surface to remove the impurities remaining on the milling cutter surface and ensure the cleanliness of the milling cutter surface.

[0028] Step 5: Perform Ti+ etching on the milling cutter, disconnect the tungsten filament power supply, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, continue to introduce Ar, power the Ti target assembly, the current is 50-120A, adjust the bias voltage to -200--1000V, and the etching time is 10-30min;

[0029] Step 6: Perform AlCrN base coating operation, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, turn off Ar, introduce appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0 Pa, turn off the power supply of the Ti target group, turn on the power supply of the AlCr target group, the target current is 80-200A, and the bias adopts a gradient process. After stabilizing at -70V for 5-10min, it is gradually increased to -100--200V in 5-10min.

[0030] Step 7: Perform multiple cycle layer coating operations, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3r / min, introduce an appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0Pa, keep the AlCr target group power on, the target current is 80-200A, and the bias voltage is adjusted to -100-200V; after 2-6 minutes, turn on the TiCrAlSiY target group power supply to make the two groups of targets work simultaneously, the TiCrAlSiY target current is 80-200A, the bias voltage is adjusted to -100-200V, and the TiCrAlSiY target group power supply is turned off after 1-3 minutes. At this point, a cycle layer of AlCrN / AlCrN+TiCrAlSiYN is completed, and this process is continued for 10-24 times;

[0031] Step 8: Perform AlCrN+TiCrAlSiYN top coating operation, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, introduce appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0Pa, and turn on the power supply of AlCr and TiCrAlSiY target groups at the same time. The target current is 80-200A, and the bias voltage is adjusted to -100--200V. After 2-5 minutes, turn off the power supply of AlCr and TiCrAlSiY target groups;

[0032] Step 9: The coating operation is carried out, and the furnace is cooled by introducing N2 into the furnace. When the temperature in the coating furnace chamber cools down to below 200°C, the furnace door is opened and the milling cutter is taken out after continuing to cool down to below 50°C.

[0033] The above descriptions are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications and substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed in the present invention are intended to be encompassed within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be subject to the scope of protection of the claims.

Claims

1. The coating structure of the milling cutter used for high-speed machining of high-strength die steel is characterized by: It includes a milling cutter base, a base layer, an intermediate layer and a top layer. The outer side of the milling cutter base is provided with a base layer, the outer side of the base layer is provided with an intermediate layer, and the outer side of the intermediate layer is provided with a top layer. The base layer is an AlCrN layer, the top layer is an AlCrN+TiCrAlSiYN mixed layer, the intermediate layer includes a plurality of periodic circulation layers arranged from the inside to the outside, each periodic circulation layer includes an AlCrN unit layer and an AlCrN+TiCrAlSiYN mixed unit layer, the AlCrN unit layer in any periodic circulation layer is arranged below the AlCrN+TiCrAlSiYN mixed unit layer, the thickness ratio of the AlCrN unit layer to the AlCrN+TiCrAlSiYN mixed unit layer in each periodic circulation layer is in the range of 1:1-3:1, and the intermediate layer includes 10-24 periodic circulation layers.

2. A method for preparing a milling cutter coating structure for high-speed machining of high-strength die steel, characterized in that: The following steps are involved: Step 1: Clean the milling cutter to be processed through spraying → ultrasonic → rough cleaning → rinsing → ultrasonic fine cleaning → rinsing → ultrasonic rinsing → pure water rinsing → dewatering → drying process; Step 2: Clamp the cleaned milling cutter onto the turret to achieve three-dimensional rotation. Load Ti target, AlCr target and TiCrAlSiY target into the coating furnace, push the turret into the furnace and close the furnace door. Step 3: Vacuum and heat the coating furnace to a vacuum degree of 4×10 -3 Pa, heating temperature to 450-500℃; Step 4: Clean the milling cutter with Ar+. Introduce Ar into the furnace, adjust the rotating frame speed to 2 r / min, energize the tungsten filament to ionize the Ar to form a glow ion beam, maintain the temperature at 450-500℃, connect the rotating frame and milling cutter to a high bias voltage of -200--400V, and let the high energy of Ar+ impact the milling cutter surface to remove the impurities remaining on the milling cutter surface and ensure the cleanliness of the milling cutter surface. Step 5: Perform Ti+ etching on the milling cutter, disconnect the tungsten filament power supply, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, continue to introduce Ar, power the Ti target assembly, the current is 50-120A, adjust the bias voltage to -200--1000V, and the etching time is 10-30min; Step 6: Perform AlCrN base coating operation, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, turn off Ar, introduce appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0 Pa, turn off the power supply of the Ti target group, turn on the power supply of the AlCr target group, the target current is 80-200A, and the bias adopts a gradient process. After stabilizing at -70V for 5-10min, it is gradually increased to -100--200V in 5-10min. Step 7: Perform multiple cycle layer coating operations, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, introduce an appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0Pa, keep the AlCr target group power on, the target current is 80-200A, and the bias voltage is adjusted to -100-200V; after 2-6 minutes, turn on the TiCrAlSiY target group power so that the two groups of targets work simultaneously, the TiCrAlSiY target current is 80-200A, the bias voltage is adjusted to -100-200V, and the TiCrAlSiY target group power is turned off after 1-3 minutes. At this point, a cycle layer of AlCrN / AlCrN+TiCrAlSiYN is completed, and this process is continued for 10-24 times; Step 8: Perform AlCrN+TiCrAlSiYN top coating operation, maintain the furnace temperature at 450-500℃, adjust the turret speed to 3 r / min, introduce appropriate amount of N2, maintain the furnace pressure in the range of 2.0-5.0Pa, and turn on the power supply of AlCr and TiCrAlSiY target groups at the same time. The target current is 80-200A, and the bias voltage is adjusted to -100--200V. After 2-5 minutes, turn off the power supply of AlCr and TiCrAlSiY target groups; Step 9: The coating operation is carried out, and the furnace is cooled by introducing N2 into the furnace. When the temperature in the coating furnace chamber cools down to below 200°C, the furnace door is opened and the milling cutter is taken out after continuing to cool down to below 50°C.

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