Surface treatment method for hard alloy coating blade

Abstract

The invention discloses a surface treatment method of a hard alloy coated blade, which comprises the following steps: S1, before the hard alloy blade is coated, wet blasting equipment is used for carrying out wet blasting on the surface of a single blade, and wet blasting parts comprise burrs at the edges and corners of the blade and a rounding cutting edge; the rounding radius ranges from 0.01 mm to 0.08 mm, and the rounding symmetry degree K value ranges from 0.7 mm to 1.3; s2, oil stains on the surface of the hard alloy blade treated in the step 1 are cleaned through ultrasonic waves, and air drying or drying is conducted; and S3, after blade coating, grinding is adopted, coatings on the clamping and supporting portions of the upper end face and the lower end face of the blade are removed through grinding, and the coatings on the periphery of a cutting edge, a chip breaker groove and the rear tool face are reserved. By means of the method, better consistency can be achieved for rounding of the cutting edge, and the stress relieving effect is better. And eliminating or reducing the internal stress of the coating on the coated blade by adopting a method of changing the continuity of a surface coating substance.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal surface treatment, and specifically relates to a set of process treatment methods for surface treatment of cemented carbide PVD or CVD coated blades before and after coating. Background Art

[0002] There is an important process in the production of cemented carbide coated blades called surface treatment, that is, the surface of cemented carbide blades needs to be surface treated before and after coating.

[0003] Before coating: The surface treatment is divided into two steps. The first step is mainly to remove the burrs on the cutting edge of the blade and eliminate the stress concentration at the edges and corners. The second step is mainly to clean the oil stains on the surface of the cemented carbide blade. Finally, the surface of the cleaned cemented carbide blade is washed, air / wind dried, and prepared for coating.

[0004] After coating: The surface treatment is mainly to eliminate the internal stress caused by the temperature difference due to coating different substances during the coating process. For PVD coatings, it is usually compressive stress, and for CVD coatings, it is usually tensile stress. The coating internal stress is one of the main reasons affecting the chipping and fracture of cemented carbide blades during use. It is very important to perform surface treatment after coating to eliminate the coating internal stress.

[0005] Currently on the market, the technical literature on surface treatment of cemented carbide PVD or CVD coated blades before and after coating mainly involves the following patents: CN109161860B, CN113529025B, CN101864554B, N101090789B, CN101870003B, CN100496824C, CN105088163A, CN2571526Y, CN107988610A, CN110408893A, CN102321873A, CN206200153U, CN106637077B, CN103171178B, CN103173761B, CN1304632C, CN105149894B, CN112775468A, CN214517777U, CN109852938A

[0006] Compared with the above patents, when the applicant performs surface treatment before and after coating, a wet blasting device is used to perform blasting processing on about 200 blades in a whole disk.

[0007] Eliminating stress at the cutting edge of cemented carbide coated inserts and within the coating is a systematic process control method. Existing technologies and patents often only propose a new technology or method for a certain point or one of the processes, rather than comprehensively considering a set of processing processes before and after the coating process. The processes affect each other, and the upper process serves the lower process, ultimately ensuring effective control of stress at the cutting edge of cemented carbide coated inserts and within the coating. Summary of the invention

[0008] In view of the shortcomings of the above-mentioned existing process technology, the present invention provides a surface treatment method for a cemented carbide coated blade. To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a surface treatment method for a cemented carbide coated blade, which comprises the following steps:

[0009] Before coating S1 carbide blades: Use wet sandblasting equipment to wet blast the single blade, and wet blast the burrs on the edges and corners of the blade. The fillet radius is 0.01-0.08mm, and the fillet symmetry K value is 0.7-1.3; remove the burrs on the blade cutting edge and eliminate the stress concentration on the edges and corners.

[0010] S2: Use ultrasonic cleaning to clean the oil stains on the surface of the carbide blade, and then air dry or dry it in an oven.

[0011] After coating the S3 blade: Grind and remove the coating on the clamping support parts of the upper and lower end surfaces of the blade, and retain the coating around the cutting edge, chip breaker groove and back face.

[0012] Through step 3, the internal stress of the coating can be eliminated or reduced or the internal stress state of the coating can be changed.

[0013] The carbide coated inserts treated by this method can effectively eliminate the burrs on the cutting edge and the internal stress at the cutting edge, and at the same time have better coating bonding strength and lower coating internal stress, which can significantly improve the anti-chipping ability of the cutting edge. At the same time, it has higher coating bonding strength and the coating is less likely to fall off.

[0014] A further improvement is that the wet spraying process is that the sand-water concentration range is between 20% and 40%, and the sand-water mixture is at a certain angle (usually between 20-70 degrees) and pressure (usually between 0.15-0.6Mpa) for a certain period of time (usually between 8-30 seconds) to continuously impact the surface of the cemented carbide blade to perform surface treatment on the single blade.

[0015] For further improvement, step 3 is replaced by the following steps: after the blade is coated: a line groove with a width of no more than 1 mm and a depth of no more than 35 μm is processed in the longitudinal middle of the back face of the cemented carbide coated blade and around the back face of the blade in a horizontal direction by using a laser ablation method;

[0016] A further improvement is that step 3 is replaced with the following steps: After the blade is coated: Using the method of slightly wet sandblasting, with a sandblasting pressure not greater than 0.4 MPa and a sand-water concentration not greater than 35%, continuously perform slightly wet sandblasting for a certain period of time. Its function is similar to shot peening. Tiny abrasive grains continuously impact the surface of the cemented carbide coated blade with the sand-water mixture, changing the stress state inside the coating. Tensile stress will become compressive stress, and the larger compressive stress will become smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The technical solution will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention.

[0018] Figure 1 Schematic structural diagram of a product for laser ablation treatment of the coated blade; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following further elaborates on the above content of the present invention according to the specific implementation manners of the embodiments. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. Without departing from the above technical idea of the present invention, various substitutions or changes made according to ordinary technical knowledge and conventional means in the art should be included within the scope of the present invention.

[0020] Embodiment 1

[0021] This embodiment provides a surface treatment method for a cemented carbide coated blade, including surface treatment before and after coating. The surface treatment before coating in S1 is divided into two steps. The first step is mainly to remove the burrs on the cutting edge of the blade and eliminate the stress concentration at the edges and corners. The process method used is to use a grinding material with numerous fine abrasive grains, mixed with water. The concentration range of the sand-water mixture is usually between 20% and 40%. The sand-water mixture impacts the surface of the cemented carbide blade at a certain angle (usually between 20 and 70 degrees) and pressure (usually between 0.15 and 0.6 Mpa) for a certain period of time (usually between 8 and 30 seconds). This process processes the blades one by one, focusing on treating the burrs at the edges and corners of the blades. The treatment result eliminates the stress concentration at the edges and corners in the form of rounding. The rounding radius can be controlled within 0.01 - 0.08 mm, and the rounding symmetry K value is 0.7 - 1.3. The K value is the ratio of the rounding length of the rake face to the rounding length of the flank face. The function of this step is to reduce the greater internal stress generated during coating at the cutting edge and prevent the occurrence of coating peeling. At the same time, due to the implementation of this step, there are many tiny uneven surfaces on the blade surface, increasing the contact surface area between the blade and the coating, thereby improving the bonding force between the coating and the cemented carbide. The second step is mainly to clean the oil stains on the surface of the cemented carbide blade. It is carried out by ultrasonic cleaning. By adding some chemical reagents, under the action of ultrasonic waves, water molecules continuously impact the oil stain molecules on the surface of the cemented carbide blade, thereby dispersing and dissolving them to achieve the purpose of removing the oil stains on the surface of the cemented carbide blade. Finally, the surface of the cleaned cemented carbide blade is washed and dried, and then prepared for coating. This step is mainly to improve the bonding force of the coating.

[0022] The surface treatment after coating in S2 is mainly to eliminate the internal stress caused by the temperature difference due to coating different substances during the coating process. For PVD coatings, it is usually compressive stress, and for CVD coatings, it is usually tensile stress. The internal stress in the coating is one of the main reasons affecting the chipping and fracture of cemented carbide blades during use. It is very important to carry out surface treatment after coating to eliminate the internal stress in the coating. The present invention has two solutions and three process methods to eliminate or reduce the internal stress in the coating. The first solution is to use the method of changing the continuity of the surface coating material to eliminate or reduce the internal stress in the coating. Method 1: Adopt grinding processing to grind and remove the coating at the clamping and supporting parts of the upper and lower end faces of the blade, and retain the coating on the periphery of the cutting edge, the chip breaker groove, and the flank face; Method 2: Adopt the method of laser burning processing, such as Figure 1, at the longitudinal center position of the flank of the cemented carbide coated blade, a groove with a width not greater than 1 mm and a depth not exceeding 35 μm is machined around the transverse direction of the flank of the blade; the second solution idea is to change the surface stress state of the coating, that is, the idea of changing tensile stress to compressive stress. Method 3 is to use the method of micro-wet sandblasting, with a sandblasting pressure not greater than 0.4 MPa and a sand-water concentration not greater than 35%, and continuously micro-wet sandblast for a certain period of time. Its function is similar to shot peening. Tiny abrasive grains continuously impact the surface of the cemented carbide coated blade with the sand-water mixture, changing the stress state inside the coating. Tensile stress will become compressive stress, and large compressive stress will become smaller.

[0023] 1. A process flow for reducing or improving the stress in the cutting edge and coating of a cemented carbide coated blade is proposed;

[0024] 2. In the first step before coating, single-piece machining is adopted, and the burrs at the edges and corners of the blade are mainly processed. The processing result eliminates the stress concentration at the edges and corners in the form of rounding. This method belongs to wet sandblasting, but it is different from the current wet sandblasting equipment processing method for whole-disk or multi-piece processing.

[0025] 3. For Method 2 of eliminating or reducing the stress in the coating after coating, the method of laser ablation machining is adopted. At the longitudinal center position of the flank of the cemented carbide coated blade, a groove with a width not greater than 1 mm and a depth not exceeding 35 μm is machined around the transverse direction of the flank of the blade.

[0026] The patented technology precisely controls the sand-water concentration, sandblasting angle, and sandblasting pressure of wet sandblasting, and performs single-piece machining on the blade. Compared with the previous wet sandblasting processing, this equipment and process can have better consistency for rounding the cutting edge and better stress elimination effect.

[0027] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A surface treatment method for a cemented carbide coated blade, characterized in that, It includes the following steps: Before coating the cemented carbide blade: Use a wet blasting device to wet blast the surface of a single blade. The wet blasting parts include the burrs at the edges and corners of the blade, and round the cutting edge; the rounding radius is 0.01 - 0.08 mm, and the symmetry K value of the rounding is 0.7 - 1.3; S2: For the cemented carbide blade processed in step 1, use ultrasonic cleaning to remove the oil stain on the blade surface, and air-dry or dry it; After blade coating: Adopt grinding processing to grind and remove the coating at the clamping and supporting parts of the upper and lower end faces of the blade, and retain the coating around the cutting edge, chip breaker groove and flank face.

2. The method according to claim 1, wherein The wet blasting process in step S1 is that the sand-water concentration range is 20% - 40%, the spraying angle of the sand-water mixture is 20 - 70 degrees, the pressure is 0.15 - 0.6 Mpa, and the spraying time lasts for 8 - 30 seconds.

3. The method according to claim 1, wherein Step 3 is replaced with the following steps: After blade coating: Adopt the method of laser ablation processing to process a wire groove with a width not greater than 1 mm and a depth not exceeding 35 um around the transverse direction of the flank face at the longitudinal middle position of the flank face of the cemented carbide coated blade.

4. The method according to claim 1, wherein Step 3 is replaced with the following steps: After blade coating: Adopt the method of micro wet blasting, the blasting pressure is less than or equal to 0.4 MPa, the sand-water concentration is less than or equal to 35%, and the spraying time lasts for 8 - 20 seconds.

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