CN110509114B

CN110509114B - Grinding and polishing method of tungsten alloy

Info

Publication number: CN110509114B
Application number: CN201910748593.2A
Authority: CN
Inventors: 郭江; 史晓琳; 宋传平; 金洙吉
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2019-08-14
Filing date: 2019-08-14
Publication date: 2021-01-05
Anticipated expiration: 2039-08-14
Also published as: CN110509114A

Abstract

A grinding and polishing method of tungsten alloy belongs to the technical field of ultra-precision processing of metal alloy. The method comprises the following specific steps: (1) coarse grinding: deionized water is selected as grinding fluid, the flow rate of the polishing fluid is set to be 6-12 ml/min, a diamond consolidated abrasive grain grinding pad with the grain size of 20-50 mu m is selected for grinding, and the grinding processing time is set to be 20-40 min. (2) And (3) fine grinding: the grain diameter of the diamond abrasive is 5-20 mu m, the processing time is set to be 40-60 min, and the rest processing parameters are the same as those of rough grinding. (3) Polishing: the polishing solution contains silica sol, a PH regulator and deionized water, the volume fraction of the silica sol abrasive is 10-25%, and the PH value is 2-5; the flow rate of the polishing solution is set to be 4-6 ml/min, the grinding pressure is set to be 20-40kpa, and the grinding processing time is set to be 1.5-2.5 h. The processing time of the whole grinding and polishing process is less than 5h, and the roughness Ra of the polished tungsten alloy surface is less than 10nm, so that the precision requirement of the actual processing field can be met, and the ultra-precision processing of the tungsten alloy is realized.

Description

Grinding and polishing method of tungsten alloy

Technical Field

The invention belongs to the technical field of metal alloy ultra-precision machining, relates to an ultra-precision machining method for metal alloy grinding and polishing, and particularly relates to a tungsten alloy grinding and ultra-precision polishing method.

Background

The tungsten alloy is an alloy with hard tungsten as a main phase and softer metals such as nickel, iron, copper, cobalt and the like as matrix phases. The tungsten alloy has not only high density, high strength, excellent thermal properties, excellent corrosion and radiation resistance, but also better ductility and processability than pure tungsten due to its special material structure. Due to the good comprehensive performance, the application of tungsten alloy in the field of ultra-precision machining gradually draws attention of people. In the field of aerospace, the tungsten alloy is mainly used for manufacturing gyroscope rotors, shock absorbers, balance weights and the like, and high-precision processing quality is favorable for ensuring the use stability of parts. In the military industry, tungsten alloys have been widely used as an excellent gamma-ray and other radiation shielding material for the production of precision parts such as radioactive source containers, collimators, medical shields and nuclear shields. Meanwhile, the tungsten alloy is used as a target or a key part in precision physical experiments such as a spallation source, nuclear energy, impact detonation physical experiment and the like, and has good surface quality, so that the accuracy of an experiment result is improved. Therefore, the tungsten alloy surface grinding and polishing technology is very important.

However, the invention patents related to the tungsten alloy grinding and polishing process are few, and a set of mature and standardized process standards is not formed at present. At present, the traditional turning processing is still the main processing means aiming at the tungsten alloy. However, because tungsten alloy has high hardness, large brittleness and large elastic deformation, a large cutting force and a high cutting temperature are generated in the machining process, so that the cutter is seriously abraded and the machining is difficult. In view of the above problems, some researchers have studied on the technology of tools and mechanics, and have improved the technology of turning tungsten alloy by introducing an auxiliary machining technology and replacing a wear-resistant tool, such as an ultrasonic-assisted dry turning method, an elliptical vibration cutting method, an ultrasonic vibration cutting method based on gas-liquid atomization cooling, and the like. Although the improved method has achieved certain results, the quality and precision of the machined surface are still difficult to meet the requirements of ultra-precision machining. Considering that the grinding and polishing process is the main means for realizing precise size, ultra-accurate shape and extremely low surface roughness in the processing of various solid materials at present, a set of grinding and polishing process aiming at tungsten alloy needs to be provided urgently.

Disclosure of Invention

In order to overcome the defects of the prior art and provide reference for the precise processing of the tungsten alloy in the future, the invention aims to provide a grinding and polishing method of the tungsten alloy, which can quickly and effectively enable the surface roughness of the tungsten alloy on the micro scale to reach the mirror surface level below 10nm and has no obvious scratches which can be measured by naked eyes on the surface.

In order to achieve the purpose, the invention adopts the technical scheme that:

a tungsten alloy grinding and polishing method is realized based on a tungsten alloy grinding and polishing device, firstly, a tungsten alloy sample 3 is bonded on a disc clamp 4 by paraffin, a grinding/polishing pad 2 is bonded on a stainless steel worktable 1, and the stainless steel worktable 1 is driven by a stepping motor. During the processing, the stainless steel working table 1 and the sample piece 3 respectively rotate around the shaft. The polishing solution device is arranged above the grinding/polishing pad 2, and in the grinding and polishing process, the polishing solution 6 drops on the grinding/polishing pad 2 to realize the auxiliary processing of grinding and polishing. The grinding and polishing method comprises the steps of preparing grinding liquid, selecting grinding and polishing parameters, selecting a grinding and polishing pad and the like, and comprises the following specific steps:

1) coarse grinding (neutral polishing solution)

The grinding liquid is deionized water, and the flow rate of the polishing liquid is set to be 6-12 ml/min. And grinding the fixed abrasive, wherein the fixed abrasive is diamond abrasive grains, the grain size of the fixed abrasive is 20-50 mu m, and the grinding pad is a grinding pad with the diamond fixed abrasive grains. The rotating speed of the processing disc is set to be 60-120 rmp, the rotating speed of the workpiece is set to be 50-110 rmp, and the grinding pressure is set to be 40-80 kpa by adding a balance weight disc or a balance weight. The processing time is set to be 20-40 min. And after the rough grinding is finished, cleaning the surface of the workpiece by using water, and drying by using an air gun.

2) Lapping (neutral polishing solution)

The grain size of the finely ground diamond abrasive is 5-20 mu m, the processing time is set to be 40-60 min, and other parameter settings (such as polishing solution flow, processing disc and workpiece rotating speed) are the same as those of the rough grinding process. And after finishing lapping, cleaning the surface of the workpiece by using water, and drying by using an air gun.

3) Preparing mixed polishing solution

The mixed polishing solution comprises a pH regulator, a silica sol solution and deionized water, the pH value of the mixed solution is guaranteed to be 2-5, and the concentration of the silica sol is set to be 10-25 vol%. The pH regulator is one or more of citric acid crystal, malic acid crystal and phosphoric acid solution; the silica sol solution contains silica abrasive grains with the grain diameter of 65-80 nm.

4) Polishing (acid polishing solution)

Dropping the polishing liquid prepared in the step 3) on a polishing pad, wherein the flow rate of the polishing liquid is set to be 4-6 ml/min. Polishing free abrasive, wherein the abrasive is silicon dioxide abrasive particles with the particle size of 65-80 nm, and the polishing pad is IC 1000/Suba IV. The rotating speed of the processing disc is set to be 50-80 rmp, the rotating speed of the workpiece is set to be 40-70 rmp, and the grinding pressure is set to be 20-40kpa by adding the balance weight disc or the balance weight. The processing time is set to be 1.5-2.5 h. And after polishing, cleaning the surface of the workpiece by water, and blow-drying by an air gun, wherein the roughness Ra of the polished tungsten alloy surface is less than 10 nm.

The invention has the beneficial effects that: the automatic grinding and polishing method of the tungsten alloy is realized by applying a simple device, and the roughness Ra of the polished tungsten alloy surface is less than 10 nm. The processing time of the whole grinding and polishing process is less than 5h, the precision requirement of the actual processing field can be met, and the ultra-precision processing of the tungsten alloy is realized.

Drawings

FIG. 1 is a schematic diagram of a grinding and polishing process;

FIG. 2 is a flow chart of the lapping and polishing process.

In the figure: 1, a stainless steel workbench; 2 a grinding/polishing pad; 3, tungsten alloy sample pieces; 4, a disc clamp; 5, a counterweight plate; 6, polishing solution.

Detailed Description

The following describes the embodiments of the present invention in detail with reference to the technical solutions.

The tungsten alloy sample 3 is made of 95W-3.5Ni-1.5Fe alloy, which is sintered from reduced tungsten powder, nickel carbonyl powder and carbonyl powder with average diameters of 2.5 μm, 2.5 μm and 3.5 μm, and has a machining size of phi 15 × 7mm³. 3 tungsten alloy samples 3 are uniformly adhered to the circumference of a clamp 4 with the diameter of phi 100mm by paraffin, and the samples 3 are loaded with pressure by a seed preparation disc 5. The polishing pad 2 is bonded to a stainless steel table 1 of a polishing machine. The polishing solution device is arranged above the polishing pad 2, and the polishing solution 6 is dropped on the grinding pad 2 to realize the auxiliary processing of grinding and polishing.

1) The polishing solution is deionized water, and the flow rate of the polishing solution is set to be 8.5 ml/min. And grinding the fixed abrasive material, wherein the fixed abrasive material is diamond abrasive particles with the particle size of 15-25 mu m, and the grinding pad 2 is a diamond fixed abrasive particle grinding pad. The machining disk speed was set at 70rmp, the workpiece speed at 60rmp, and the grinding load pressure at 59 kpa. The processing time was set to 30 min. And after the rough grinding is finished, cleaning the surface of the workpiece by using water, and drying by using an air gun.

2) And replacing the grinding pad, ensuring the grain diameter of the finely ground diamond grinding material to be 5-10 mu m, setting the processing time to be 40min, and setting other parameters such as polishing solution flow, the rotating speed of a processing disc and a workpiece and the like to be the same as those in the rough grinding process. And after finishing lapping, cleaning the surface of the workpiece by using water, and drying by using an air gun.

3) Preparing a mixed polishing solution: the mixed polishing solution comprises an acidic solution, a silica sol solution and deionized water, wherein the acidic solution is adjusted by citric acid crystals, and the pH value of the mixed solution is set to be 4. The silica sol solution contained silica abrasive grains having a grain size of 72nm, and the silica sol concentration was set at 15 vol.%.

4) And replacing the polishing pad, and dropping the polishing liquid on the polishing pad, wherein the flow rate of the polishing liquid is set to be 5.5 ml/min. Free abrasive is used for polishing, the abrasive is silicon dioxide abrasive particles, and the polishing pad is IC 1000/Suba IV. The machining disk speed was set at 60rmp, the workpiece speed was set at 50rmp, and the polishing load pressure was set at 29 kpa. The processing time was set to 1.5 h. And after polishing, cleaning the surface of the workpiece by using water, and blow-drying by using an air gun, wherein the roughness of the polished tungsten alloy surface reaches Ra 7 nm.

The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but includes equivalent technical means as would be recognized by those skilled in the art based on the inventive concept.

Claims

1. A grinding and polishing method of tungsten alloy is realized based on a grinding and polishing device of tungsten alloy, a polishing solution device is arranged above a grinding/polishing pad, a tungsten alloy sample piece is bonded on a disc clamp, the grinding/polishing pad is bonded on a stainless steel working table, and the stainless steel working table is driven by a stepping motor; in the processing process, the stainless steel working table and the sample piece respectively rotate around a shaft, and polishing liquid drops fall on the grinding/polishing pad, and the grinding and polishing method is characterized by comprising the following steps:

1) coarse grinding

The grinding fluid is deionized water, and the flow rate of the grinding fluid is set to be 6-12 ml/min; grinding the consolidated diamond abrasive, wherein the grinding pad is a grinding pad with diamond consolidated abrasive grains; the rotating speed of the stainless steel workbench is set to be 60-120 rmp, the rotating speed of the workpiece is set to be 50-110 rmp, and the grinding pressure is 40-80 kpa; the processing time is set to be 20-40 min; after coarse grinding is finished, cleaning the surface of the workpiece by water, and drying by using an air gun;

2) lapping

The grain size of the finely ground diamond abrasive is smaller than that of the diamond abrasive in the step 1), the processing time is set to be 40-60 min, and other parameter settings are the same as those of the rough grinding process; after finishing lapping, cleaning the surface of the workpiece by water, and drying by using an air gun;

3) preparing mixed polishing solution

The mixed polishing solution comprises a pH regulator, a silica sol solution and deionized water, the pH value of the mixed solution is guaranteed to be 2-5, and the concentration of the silica sol is set to be 10-25 vol%; the silica sol solution contains silica abrasive particles;

4) polishing of

Dropping the polishing liquid prepared in the step 3) on a polishing pad, wherein the flow rate of the polishing liquid is set to be 4-6 ml/min; polishing free abrasive, wherein the abrasive is silicon dioxide abrasive particles with the particle size of 65-80 nm, and the polishing pad is IC 1000/Suba IV; the rotating speed of the stainless steel workbench is set to be 50-80 rmp, the rotating speed of the workpiece is set to be 40-70 rmp, and the grinding pressure is 20-40 kpa; the processing time is set to be 1.5-2.5 h; and cleaning the surface of the workpiece by water after polishing, drying by using an air gun, and enabling the roughness Ra of the polished tungsten alloy surface to be less than 10 nm.

2. The method of claim 1, wherein the grinding pressure is set by adding a weight plate or a weight.

3. The method for grinding and polishing tungsten alloy according to claim 1, wherein the diamond abrasive in step 1) has a particle size of 20 to 50 μm.

4. The method for grinding and polishing tungsten alloy according to claim 1, wherein the diamond abrasive in step 2) has a particle size of 5 to 20 μm.

5. The method as claimed in claim 1, wherein the pH regulator in step 3) is one or more of citric acid crystal, malic acid crystal, and phosphoric acid solution.

6. The method for grinding and polishing tungsten alloy according to claim 1, wherein the silica abrasive grains in the silica sol solution in the step 3) have a grain size of 65 to 80 nm.