Method for in-situ preparation of woodworking tool based on laser alloying technology

Abstract

The invention belongs to the technical field of material surface modification, and provides a method for in-situ preparation of a woodworking tool based on a laser alloying technology, and an alloying modified layer with excellent mechanical and cutting performance is formed in situ on a cheap tool body blade part through optimal design of alloying components and effective regulation and control of a technological process. The requirements of the woodworking tool for comprehensive performance such as high hardness, high wear resistance, high thermal stability, good obdurability and the like under the cutting conditions of high speed and impact load bearing are met. Meanwhile, the method has the advantages of being simple in technological process, high in preparation efficiency, wide in adaptability, high in economical efficiency and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of material surface modification and provides a method for in-situ preparation of woodworking tools based on laser alloying technology. Background Art

[0002] In recent years, with the rapid development of the wood-based panel industry and the wood processing industry, higher requirements have been placed on the advancement, practicality, and manufacturing precision of woodworking tools. The materials used to make tools are gradually evolving from tool steel and high-speed steel to hard materials. However, due to the inherent hardness and brittleness of hard materials and their high price, hard woodworking tools generally have the common problem of poor processability and economic efficiency. Based on this, the following two methods are currently used to manufacture hard woodworking tools: one is the split welding method, which is to weld the hard material blade to the steel tool body. While ensuring good impact resistance of the tool, the hard material is used to improve the wear resistance of the cutting edge. However, due to the limitations of the powder metallurgy process itself, there are great limitations in the manufacture of blades with complex geometric shapes. In addition, cemented carbide has low strength and toughness, and the blade sharpness is low, which makes it difficult to meet the requirements of wood finishing. In addition, hard materials have poor weldability and are prone to metallurgical defects such as pores and cracks during welding, which directly affect the cutting performance and durability of woodworking tools. Therefore, there are strict requirements for both welding technology and process, and the manufacturing process is very complex. The second method is the coating method, which uses surface modification technologies such as physical and chemical vapor deposition to deposit a hard film on the surface of the tough steel tool body. The high wear resistance and heat resistance of the hard film are used to improve the cutting performance of the tool. However, due to the weak physical interface between the film and the substrate, the hard film is prone to peeling during high-speed cutting and under alternating impact loads. Therefore, the improvement in tool durability is very limited, and it also fails to fundamentally solve the problem of poor toughness and impact resistance of hard materials. Given the bottleneck problem of the difficulty in reconciling the hardness, wear resistance, strength and toughness of single hard materials, as well as the limitations of existing manufacturing processes, it is of great practical significance to develop new composite tool materials and explore new tool manufacturing methods.

[0003] Laser alloying technology utilizes a high-energy laser beam to heat and melt the substrate surface layer with added elements, causing the mixture to rapidly solidify, thereby forming a new surface alloy layer based on the original substrate. This technology offers numerous unique advantages: uniform and fine microstructure and superior performance; high flexibility for localized processing of complex structural parts, and precise control of the alloying layer depth; a wide range of alloy systems; low substrate thermal effects and minimal workpiece deformation; high production efficiency, and low process costs. Based on this, the present invention develops a method for in-situ fabrication of woodworking tools on inexpensive substrates using laser alloying technology, through optimized design of alloying components and effective control of the process. Summary of the Invention

[0004] The purpose of the present invention is to overcome the bottleneck limitations of existing woodworking tool manufacturing technology and provide a method for in-situ preparation of woodworking tools based on laser alloying technology. Through high-throughput structural simulation analysis and a large number of experimental studies, the optimal ratio range of alloying components is determined, and through effective regulation of alloying process parameters and processes, an alloying layer with excellent mechanical and cutting properties is formed in situ on the cutting edge of a cheap tool body to meet the comprehensive performance requirements of woodworking tools such as high hardness, high wear resistance, high thermal stability, good strength and toughness under high-speed cutting conditions and impact loads, and significantly reduce manufacturing costs.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A method for in-situ preparation of woodworking tools based on laser alloying technology, including rough processing of tool body material, design of alloying powder composition, preparation and pre-setting of alloying powder, laser alloying and subsequent mechanical processing; The method comprises the following steps: (1) Rough processing of the tool body material: Select tempered steel or tool steel with good strength and toughness and low price as the tool body material. After the cutting and straightening process, it is ground into the tool body blank of the required shape and size; (2) Alloying powder composition design: WC, TiC, NbC, Mo, Al and La powders with a particle size of 10-50 μm were selected as raw materials, and the optimal composition ratio range was: (10-20 wt.%) TiC-(0.5-1.0 wt.%) NbC-(0.2-0.6 wt.%) Mo-(0.4-0.8 wt.%) Al-(0.5-1.0 wt.%) La-WC; (3) Preparation and pre-setting of alloying powder: The alloying powder is weighed and proportioned according to the chemical composition in step (2), and placed in a ball mill. It is mixed with anhydrous ethanol as the ball milling medium at a speed of 100-150 rpm for 6-10 hours. Then, anhydrous ethanol and shellac with a volume ratio of 99:1 are used to prepare a suspension of the mixed alloying powder. The suspension is evenly sprayed onto the front cutting edge of the blade using a spray gun to form a spray layer with a thickness of 0.4-0.8 mm. (4) Laser alloying: After the spray coating is naturally dried, the blade body is placed in a fixture on the laser processing system platform, and then laser alloying treatment is performed along the contour of the front cutting edge under the drive of the CNC system to form an alloyed modified layer with high hardness, high wear resistance, high thermal stability and good toughness on the cutting edge surface; the optimized laser alloying parameters are: laser power of 1.5~2.5KW, scanning speed of 6~15mm / s, spot size of 2~6mm, overlap rate of 0~50%, and shielding gas flow rate of 15~20L / min; (5) Subsequent machining: After the laser alloying treatment, the front cutting edge is finely ground using a tool grinder with a grinding depth of less than 0.1 mm, and then the back cutting edge is sharpened using a profile grinder to process it into the final cutting edge shape and dimensional accuracy, thereby realizing the preparation of woodworking tools.

[0006] The implementation of the present invention will have the following beneficial effects: (1) Excellent mechanical properties: Due to the formation of a fine composite structure reinforced by multiple hard phases, the in-situ alloyed blade exhibits excellent mechanical properties. Its hardness at room temperature and 600°C is comparable to that of cemented carbide, reaching HRC65~78 and HRC58~72 respectively, while its flexural strength and impact toughness are increased by 17~28% and 20~35% respectively compared with the latter.

[0007] (2) Excellent cutting performance and high durability: Due to the excellent mechanical properties and high thermal stability of the alloyed blade, not only can the blade be sharpened to effectively improve the quality and precision of wood processing, but also the wear resistance of the tool is significantly increased, resulting in its service life being 1 to 2 times longer than that of carbide tools.

[0008] (3) Strong interface bonding: Different from surface modification technologies such as physical and chemical vapor deposition, the laser alloying modified layer and the substrate have a strong metallurgical interface bonding. In addition, due to the radial distribution of the temperature field in the laser action area, the microstructure shows a gradual transition from the alloying layer to the substrate. This can effectively reduce the stress concentration generated by the cutting edge during high-speed cutting and impact load, thereby inhibiting the initiation and expansion of cracks and improving the service life of the tool.

[0009] (4) High applicability: The materials suitable for laser alloying of tool bodies are very wide (such as various quenched and tempered steels and tool steels, etc.), and the ratio of alloying components can be flexibly adjusted based on the properties of the substrate to achieve the required target performance. It can also flexibly implement local laser alloying on tool bodies of any complex geometry, so it can be widely used in the manufacture of various woodworking planers and milling cutters.

[0010] (5) High economy: Since the blade is locally alloyed on a relatively cheap tool body, the alloying powder material is less and the utilization rate is high. In addition, the laser alloying process is simple and efficient, and does not require complicated powder metallurgy and subsequent welding processes. As a result, its processing cost is reduced by 50~70% compared with split-welded cemented carbide, and the economic benefits are very objective. DETAILED DESCRIPTION

[0011] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0012] Example 1: Normalized 9SiCr alloy tool steel was selected as the tool body material of the die. After cutting and straightening, it was ground into a die blank with a size of 300mm×30mm×3mm using a tool grinder.

[0013] WC, TiC, NbC, Mo, Al and La powders with a particle size of 10μm~50μm were weighed and mixed in a mass percentage of 83.5:14:0.5:0.5:0.5:1, placed in a ball mill, and mixed at a speed of 150r / min for 8h using anhydrous ethanol as the ball milling medium. Then, the alloyed powder was prepared into a suspension using anhydrous ethanol and shellac with a volume ratio of 99:1, and evenly sprayed onto the front cutting edge of the tool body with a spray gun (the spray layer thickness is about 0.8mm).

[0014] After the spray coating is naturally dried, the tool body is placed in a water-cooled copper fixture on the 6KW fiber laser work platform. Then, driven by the CNC system, a U-shaped overlapping laser scanning is performed along the complex geometric contour of the front cutting edge to reduce thermal stress and reduce tool body deformation. The specific process parameters are laser power 1.8kW, spot diameter 6mm, scanning speed 13mm / s, overlap amount 50%, and argon flow rate 20L / min. Finally, a laser alloying modification layer with a depth of 2.0mm and a width of 10mm is obtained on the cutting edge.

[0015] After laser alloying, the front and rear cutting surfaces of the mold tool are finely ground using a profile grinder to the final shape and dimensional accuracy (grinding depth is less than 0.1mm), thereby producing a mold tool with a complex geometric shape on the blade.

[0016] Example 2: The quenched and tempered 45 steel was selected as the double-sided planer blade material. After cutting and straightening, it was ground into a double-sided planer blade blank with a size of 330mm×17mm×4.5mm using a tool grinder.

[0017] WC, TiC, NbC, Mo, Al and La powders with a particle size of 10μm~50μm were weighed and mixed in a mass percentage of 76.6:20:1:0.6:0.8:1, placed in a ball mill, and mixed at a speed of 100r / min for 10h using anhydrous ethanol as the ball milling medium. Then, the alloyed powder was prepared into a suspension using anhydrous ethanol and shellac with a volume ratio of 99:1, and evenly sprayed onto the front cutting edge of the tool body with a spray gun (the spray layer thickness is about 0.6mm).

[0018] After the spray coating dried naturally, the tool body was placed in a water-cooled copper fixture on the work platform of a 6kW fiber laser. Driven by a CNC system, laser scanning was performed along the edge contours on both sides of the tool body's rake face. The specific process parameters were: laser power 2.0kW, spot diameter 5mm, argon flow rate 20L / min, overlap 50%. The edges on both sides were alloyed at two different scanning speeds of 9mm / s and 10mm / s, respectively. This solved the problem of different microstructures and deformation on both sides of the edge due to heat accumulation. Finally, a laser alloyed modified layer with a depth of 1.8mm and a width of 6mm was obtained on both sides of the tool edge. After laser alloying treatment, the front cutting edge is finely ground using a tool grinder (grinding depth is less than 0.1mm), and then the two sides of the back cutting edge are sharpened in turn using a profile grinder to process them into the final cutting edge shape and dimensional accuracy, thereby producing a double-sided planer.

[0019] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for in-situ preparation of woodworking tools based on laser alloying technology, characterized in that: Including rough machining of tool body material, design of alloying powder composition, preparation and presetting of alloying powder, laser alloying and subsequent mechanical processing; The method comprises the following steps: (1) Rough processing of the tool body material: Select quenched and tempered steel or tool steel with good strength and toughness and low price as the tool body material. After cutting and straightening processes, use grinding to make it into a tool body blank of the required shape and size; (2) Alloying powder composition design: WC, TiC, NbC, Mo, Al and La powders with a particle size of 10-50 μm were selected as raw materials, and the optimal composition ratio range was: (10-20 wt.%) TiC-(0.5-1.0 wt.%) NbC-(0.2-0.6 wt.%) Mo-(0.4-0.8 wt.%) Al-(0.5-1.0 wt.%) La-WC; (3) Preparation and presetting of alloying powder: The alloying powder is weighed and proportioned according to the chemical composition in step (2), and placed in a ball mill. It is mixed with anhydrous ethanol as a ball milling medium at a speed of 100-150 rpm for 6-10 hours. Then, anhydrous ethanol and shellac in a volume ratio of 99:1 are used to prepare a suspension of the mixed alloying powder, and the suspension is evenly sprayed onto the front cutting edge of the blade body with a spray gun to form a spray layer with a thickness of 0.4-0.8 mm. (4) Laser alloying: After the spray layer is naturally dried, the tool body is placed in a fixture on the laser processing system platform, and then laser alloying treatment is performed along the contour of the front blade under the drive of the CNC system to form an alloyed modified layer with high hardness, high wear resistance, high thermal stability and good toughness on the blade surface; the optimized laser alloying parameters are: laser power of 1.5~2.5KW, scanning speed of 6~15mm / s, spot size of 2~6mm, overlap rate of 0~50%, and shielding gas flow rate of 15~20L / min; (5) Subsequent machining: After the laser alloying treatment, the front cutting edge is finely ground by a tool grinder with a grinding depth of less than 0.1 mm, and then the back cutting edge is sharpened by a profile grinder to achieve the final cutting edge shape and dimensional accuracy, thereby realizing the preparation of woodworking tools.