阅读说明：本技术 一种基于搅拌摩擦处理的高精度金属镜面加工方法 (High-precision metal mirror surface machining method based on stirring friction treatment ) 是由 何春雷 王姝淇 任成祖 耿昆 张婧 李东洋 于 2021-09-23 设计创作，主要内容包括：本发明公开了一种基于搅拌摩擦处理的高精度金属镜面加工方法,包括以下步骤：使用柱状搅拌头对金属工件的整个上表面进行搅拌摩擦处理；将完成处理的金属工件浸没到液氮中处理；将金属工件从液氮中取出放置到室温环境中,在通风的条件下放置85-90天；将金属工件安装在超精密加工车床上,采用聚晶金刚石刀具对金属工件上表面进行加工,直至将金属工件上表面搅拌摩擦处理痕迹全部去除；然后采用单晶金刚石刀具对金属工件进行加工,直至将金属工件上表面全部进行车削之后。采用本方法可以降低超精密车削镜面的表面粗糙度、提高金属镜面加工精度。(The invention discloses a high-precision metal mirror surface processing method based on friction stir processing, which comprises the following steps of: performing stirring friction treatment on the whole upper surface of the metal workpiece by using a columnar stirring head; immersing the processed metal workpiece into liquid nitrogen for processing; taking out the metal workpiece from the liquid nitrogen, placing the metal workpiece in a room temperature environment, and placing the metal workpiece for 85-90 days under a ventilation condition; mounting the metal workpiece on an ultra-precision machining lathe, and machining the upper surface of the metal workpiece by adopting a polycrystalline diamond cutter until all friction stir processing traces on the upper surface of the metal workpiece are removed; and then processing the metal workpiece by using a single crystal diamond cutter until the upper surface of the metal workpiece is completely turned. The method can reduce the surface roughness of the ultra-precision turning mirror surface and improve the processing precision of the metal mirror surface.)

1. A high-precision metal mirror surface processing method based on stirring friction treatment is characterized by comprising the following steps:

fixing a metal workpiece on a workbench of a friction stir machine tool, and performing friction stir processing on the whole upper surface of the metal workpiece by using a columnar stirring head;

step two, rapidly taking down the processed metal workpiece from the workbench, and immersing the metal workpiece in liquid nitrogen for processing for 15-30 min;

taking the metal workpiece out of the liquid nitrogen, placing the metal workpiece in a room temperature environment at the temperature of 23-25 ℃, and placing the metal workpiece for 85-90 days under a ventilation condition;

step four, mounting the metal workpiece in the step three on an ultra-precision machining lathe, and adjusting the dynamic balance parameter of a lathe spindle to be within 30 nm; processing the upper surface of the metal workpiece by adopting a polycrystalline diamond cutter until all friction stir processing traces on the upper surface of the metal workpiece are removed;

and fifthly, adjusting the dynamic balance parameters of the lathe spindle to be within 30nm, then machining the metal workpiece by adopting a single crystal diamond cutter until the upper surface of the metal workpiece is completely turned, taking down the workpiece and cleaning the workpiece, and thus finishing the manufacturing process of machining the workpiece into the high-precision mirror surface.

2. The friction stir processing-based high precision metal mirror finishing method according to claim 1, wherein: and the columnar stirring head is used for performing stirring friction treatment on the upper surface of the metal workpiece along the annular or linear direction.

3. The friction stir processing-based high precision metal mirror finishing method according to claim 1 or 2, wherein: the technological parameters of the stirring head in the stirring friction treatment process are as follows: the moving speed of the stirring head is 100-500mm/min, the rotating speed is 400-1600r/min, the rotating direction is anticlockwise, the inclination angle of the stirring head is 1-3 degrees, and the pressing amount is 0.1-0.3 mm.

4. The friction stir processing-based high precision metal mirror finishing method according to claim 1 or 2, wherein: the process parameters in the fourth step are as follows: the main shaft rotation speed is 1000-.

5. The friction stir processing-based high precision metal mirror finishing method according to claim 4, wherein: the turning technological parameters in the fifth step are as follows: the main shaft rotation speed is 1000-3000r/min, the cutting depth is 3-5 μm, and the feed amount per revolution is 1-5 μm/r.

Technical Field

The invention relates to a metal processing method, in particular to a processing method of a high-precision metal mirror surface.

Background

The high-precision metal mirror surface is widely applied to the key technical fields of deep space exploration, astronomical observation and the like, and is mainly manufactured by an ultra-precision turning method at present. Under the conditions of using a high-precision numerical control machine tool and strictly controlling the vibration, temperature, humidity, and the like of the processing environment, it has been possible to obtain a metal mirror surface with a nano-scale surface roughness. At present, the key factor for limiting the further improvement of the metal mirror finishing precision is the metallographic structure of the material. Specifically, the metal material used for mirror finishing is generally a polycrystalline material, and the grain size of the metal is large and the uniformity of the orientation of the grains is poor due to the influence of factors such as the solidification rate during the production of the polycrystalline material. The different orientations of the metal crystal grains lead to different mechanical properties of the adjacent metal crystal grains, so that the elastic recovery values of the adjacent metal crystal grains after turning are different, and finally the surface roughness of the metal mirror surface subjected to ultra-precise turning is obviously increased. Therefore, the machining accuracy of the metal mirror surface cannot be further improved due to the influence of the metallographic structure of the conventional metal material.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a high-precision metal mirror surface processing method based on friction stir processing, which can further improve the metal mirror surface processing precision.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the invention relates to a high-precision metal mirror surface processing method based on friction stir processing, which comprises the following steps of:

fixing a metal workpiece on a workbench of a friction stir machine tool, and performing friction stir processing on the whole upper surface of the metal workpiece by using a columnar stirring head;

step two, rapidly taking down the processed metal workpiece from the workbench, and immersing the metal workpiece in liquid nitrogen for processing for 15-30 min;

taking the metal workpiece out of the liquid nitrogen, placing the metal workpiece in a room temperature environment at the temperature of 23-25 ℃, and placing the metal workpiece for 85-90 days under a ventilation condition;

step four, mounting the metal workpiece in the step three on an ultra-precision machining lathe, and adjusting the dynamic balance parameter of a lathe spindle to be within 30 nm; processing the upper surface of the metal workpiece by adopting a polycrystalline diamond cutter until all friction stir processing traces on the upper surface of the metal workpiece are removed;

and fifthly, adjusting the dynamic balance parameters of the lathe spindle to be within 30nm, then machining the metal workpiece by adopting a single crystal diamond cutter until the upper surface of the metal workpiece is completely turned, taking down the workpiece and cleaning the workpiece, and thus finishing the manufacturing process of machining the workpiece into the high-precision mirror surface.

The invention has the beneficial effects that:

by carrying out friction stir treatment on the metal material, the grain size of the metal material can be effectively reduced, the orientation consistency of the grains is improved, and the metallographic structure of the metal material is improved, so that the surface roughness of the ultra-precision turning mirror surface is reduced, and the processing precision of the metal mirror surface is improved.

Detailed Description

The technical solutions of the present invention are described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

The invention relates to a high-precision metal mirror surface processing method based on friction stir processing, which comprises the following steps of:

fixing a metal workpiece on a workbench of a friction stir machine tool, and performing friction stir processing on the whole upper surface of the metal workpiece by using a columnar stirring head;

the stirring friction treatment of the columnar stirring head on the upper surface of the metal workpiece can be carried out along the annular direction or the linear direction;

the preferable technological parameters of the stirring head in the friction stir processing process are as follows: the moving speed of the stirring head is 100-500mm/min (such as 100mm/min, 400mm/min and 500mm/min), the rotating speed is 400-1600r/min, the rotating direction is anticlockwise, the inclination angle of the stirring head (referring to the included angle between the axis of the stirring head and the vertical direction) is 1-3 degrees (such as 1 degree, 2 degree and 3 degree), and the pressing amount is 0.1-0.3mm (such as 0.1mm, 0.2mm and 0.3 mm). The method has the advantages that the metallographic structure of the surface layer and the subsurface layer of the metal workpiece can be effectively refined, and the stirring head is ensured not to be deformed excessively.

And step two, quickly taking down the processed metal workpiece from the workbench, and immersing the metal workpiece in liquid nitrogen for processing for 15-30min (for example, 15min, 20min and 30 min).

And step three, taking the metal workpiece out of the liquid nitrogen, placing the metal workpiece in a room temperature environment with the temperature of 23-25 ℃, and placing the metal workpiece for 85-90 days under the ventilation condition.

And step four, mounting the metal workpiece in the step three on an ultra-precision machining lathe (generally, a high-precision lathe with main shaft rotation runout less than or equal to 50nm and guide rail linearity tolerance less than or equal to 0.3 mu m/250 mm), and adjusting the dynamic balance parameters of a lathe main shaft to be within 30 nm. And processing the upper surface of the metal workpiece by adopting a polycrystalline diamond cutter until the stir friction processing traces on the upper surface of the metal workpiece are completely removed.

The recommended process parameters are: the main shaft rotation speed is 1000-3000r/min (such as 1000r/min, 2000r/min, 3000r/min), the cutting depth is 3-15 μm (such as 3 μm, 10 μm, 15 μm), and the feed amount per revolution is 10-30 μm/r (such as 10 μm/r, 20 μm/r, 30 μm/r). The advantages are that the wear rate of the polycrystalline diamond cutter can be reduced, and the surface of the workpiece with low surface roughness is obtained.

And fifthly, adjusting the dynamic balance parameters of the lathe spindle to be within 30nm, then machining the metal workpiece by adopting a single crystal diamond cutter until the upper surface of the metal workpiece is completely turned, taking down the workpiece and cleaning the workpiece, and thus finishing the manufacturing process of machining the workpiece into the high-precision mirror surface.

The recommended turning process parameters are: the spindle rotation speed is 1000-3000r/min (such as 1000r/min, 2000r/min and 3000r/min), the cutting depth is 3-5 μm (such as 3 μm, 4 μm and 5 μm), the feed per revolution is 1-5 μm/r (such as 1 μm/r, 3 μm/r and 5 μm/r), and the advantages are that the wear speed of the single crystal diamond cutter can be reduced, and the workpiece surface with low surface roughness can be obtained.

Example 1

And carrying out a cutting test to verify the method. The workpiece material is high-conductivity oxygen-free copper, the processing equipment is a Nanoform700 Ultra-precision processing machine tool, the tool is a natural single crystal diamond tool, and the arc radius of the tool tip is 2029 microns. The technological parameters of the friction stir treatment are as follows: the moving speed of the stirring head is 300mm/min, the rotating speed is 800r/min, the rotating direction is anticlockwise, the inclination angle of the stirring head is 1 degree, and the pressing amount is 0.1 mm.

The technological parameters of the polycrystalline diamond cutter are as follows: the main shaft rotating speed is 1200r/min, the cutting depth is 10 mu m, and the feed per revolution is 10 mu m/r. The technological parameters of processing by adopting the single crystal diamond cutter are as follows: the rotating speed of the main shaft is 2400r/min, the cutting depth is 5 mu m, and the feed per revolution is 5 mu m/r. The same processing technique operation is carried out on the high-conductivity oxygen-free copper material which is not subjected to the stirring friction treatment and is subjected to the stirring friction treatment under the same condition.

After the machining is finished, the peak-valley value of the roughness of the machined surface is measured by using a white light interferometer ZYGO Newview 9000, the measurement range is 900 microns multiplied by 900 microns, and the measurement result shows that: the peak-to-valley value of the surface roughness of the high-conductivity oxygen-free copper workpiece which is not subjected to the friction stir treatment is 23.399nm, and the peak-to-valley value of the surface roughness of the high-conductivity oxygen-free copper workpiece which is subjected to the friction stir treatment is 17.831 nm. The measurement results prove that the surface roughness of the ultra-precision turning mirror surface can be obviously reduced and the metal mirror surface processing precision can be improved by processing the metal material by stirring friction.

The foregoing description of the present invention is intended to be illustrative rather than restrictive, and therefore the embodiments of the present invention are not limited to the specific embodiments described above. It will be apparent to those skilled in the art that other variations and modifications can be made without departing from the spirit of the invention and the scope of the appended claims.