A processing and polishing method for tungsten steel nozzles

Abstract

The present invention provides a processing and polishing method for a tungsten steel nozzle, belonging to the field of nozzle processing. Compared with the prior art, the present invention provides a processing and polishing method for a tungsten steel nozzle, directly using a drill bit on a CNC to process a tungsten steel blank to form a V-groove, then applying a gas-solid-liquid three-phase mixed polishing liquid in the V-groove, and using a grinding head and an ultrasonic generator to grind and polish the V-groove to obtain a finished tungsten steel nozzle. The process is simple, the polishing accuracy is high, the efficiency is high, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of machining, and particularly to a method for machining and polishing a tungsten steel nozzle. Background Art

[0002] Parts such as tungsten steel nozzles used in ultra-precision piezoelectric valves usually have a mating surface with a V-shaped or hemispherical shape (hereinafter simply referred to as: V-groove) with the striker. Since the striker uses an outer circle, it is relatively easy to machine it into a standard hemisphere, and the positional tolerance of its contour can be economically achieved within 2 μm. However, the groove of nozzle parts is an inner concave surface, and the material is tungsten steel with a hardness that can reach 89HRA - 95HRA, making the machining very difficult. The surface roughness of both needs to reach Ra0.1 μm. Therefore, it is very difficult to economically achieve the above-mentioned precision and surface roughness.

[0003] The machining of the V-groove of cemented carbide (commonly known as: tungsten steel) is a difficult point because cemented carbide itself is used to make metal cutting tools and generally requires grinding machine machining. However, for such tapered holes, the grinding machine cannot complete the machining. In the current industry, electrolytic grinding machines or electrical discharge machining are usually used. Due to the very sharp tip of the grinding head of the electrolytic grinding machine, the grinding head wears very quickly, so the cost of machining this V-groove is very high. For electrical discharge machining, it is necessary to first use CNC to make the electrode, and then use a precision electrical discharge machine tool for electrical discharge machining. The process is cumbersome, the efficiency is extremely low, and the cost is also high. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for machining and polishing a tungsten steel nozzle, which has simple processes, high polishing precision, high efficiency, and reduced costs.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for machining and polishing a tungsten steel nozzle, characterized by comprising the following steps:

[0007] (1) Using a tungsten steel drill bit with a PCD coating on a CNC to machine a tungsten steel blank to form a semi-finished tungsten steel nozzle with a V-groove;

[0008] (2) Coating a gas-solid-liquid three-phase mixed polishing liquid in the V-groove of the semi-finished tungsten steel nozzle in step (1);

[0009] (3) Separately installing a grinding head motor and a part motor on a workbench, and connecting an ultrasonic generator to the grinding head motor;

[0010] (4) Clamping the semi-finished tungsten steel nozzle coated with the polishing liquid in step (2) on the part motor, and making the grinding head on the grinding head motor slightly contact a horizontal direction turning contour line of the nozzle, with the gap between the grinding head and the side wall of the V-groove of the nozzle being between 0 and 0.05 mm;

[0011] (5) Turn on the grinding head motor, the part motor and the ultrasonic generator to grind and polish the V-groove of the semi-finished tungsten carbide nozzle.

[0012] (6) Turn off the grinding head motor, the part motor and the ultrasonic generator to obtain the finished tungsten carbide nozzle.

[0013] Preferably, in step (1), the top of the tungsten carbide drill bit has a short cross edge with an inclination angle.

[0014] More preferably, the length of the short cross edge is 0.2 mm, and the cutting edge is a three-order arc that gradually decreases from the periphery to the center.

[0015] Preferably, the preparation steps of the gas-solid-liquid three-phase mixed polishing liquid in step (2) include: 2.1) Mix the cooling oil and the single crystal diamond micropowder, and the volume ratio is 5:1 to 6:1; the particle size of the single crystal diamond micropowder is 600 nm - 800 nm; 2.2) After the cooling oil and the single crystal diamond micropowder are prepared and stirred evenly according to the above ratio, put them into a nanoscale bubble generator to fully generate nanoscale bubbles in the solid-liquid mixture.

[0016] Preferably, in step (3), the grinding head motor, the part motor and the ultrasonic generator are all installed on the marble workbench.

[0017] Preferably, the included angle between the axis of the grinding head motor and the axis of the part motor in step (3) is 165°.

[0018] Preferably, in step (5), the ultrasonic frequency is controlled between 40000 Hz and 160000 Hz, and the amplitude of the grinding head is between 0.005 mm and 0.01 mm.

[0019] Preferably, the surface roughness of the V-groove of the finished tungsten carbide nozzle in step (6) is within Ra0.1 um, and the profile tolerance is between 1 um and 1.5 um.

[0020] Preferably, after the polishing in step (6), first turn off the ultrasonic generator, then stop the grinding head motor, and then stop the part motor; retract the grinding head motor or the part motor to the workpiece installation position, and the workpiece cycle ends.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a processing and polishing method for tungsten carbide nozzles. The tungsten carbide blank is directly processed by a drill bit on a CNC to form a V-groove, and then a gas-solid-liquid three-phase mixed polishing liquid is applied in the V-groove. The V-groove is ground and polished by using a grinding head and an ultrasonic generator to obtain the finished tungsten carbide nozzle. The process is simple, the polishing accuracy is high, the efficiency is high, and the cost is reduced. Description of the Drawings

[0022] Figure 1, which is a schematic diagram of processing a tungsten carbide blank with a tungsten carbide drill bit in a tungsten carbide nozzle processing and polishing method provided by the present invention;

[0023] Figure 2 , which is a schematic diagram of a tungsten carbide drill bit used in a CNC in a tungsten carbide nozzle processing and polishing method provided by the present invention;

[0024] Figure 3 , which is a schematic diagram of the composition of a polishing liquid in a tungsten carbide nozzle processing and polishing method provided by the present invention;

[0025] Figure 4 , which is a schematic diagram of a grinding head motor grinding and polishing a tungsten carbide nozzle semi-finished product on a part motor in a tungsten carbide nozzle processing and polishing method provided by the present invention. Detailed implementation mode

[0026] Specific descriptions are made for the preferred implementation modes provided by the present invention according to the attached drawings.

[0027] The present invention provides a tungsten carbide nozzle processing and polishing method, which specifically includes the following steps:

[0028] 1) Using a tungsten carbide drill bit 1 with a PCD coating on a CNC to process a tungsten carbide blank to form a tungsten carbide nozzle semi-finished product 100 with a V-groove, as Figure 1 shown;

[0029] 2) Coating a gas-solid-liquid three-phase mixed polishing liquid in the V-groove of the tungsten carbide nozzle semi-finished product in step 1);

[0030] 3) Installing a grinding head motor 2 and a part motor 3 on a workbench 4 respectively, and connecting an ultrasonic generator 5 to the grinding head motor 2, as Figure 4 ;

[0031] 4) Clamping the tungsten carbide nozzle semi-finished product coated with the polishing liquid in step 2) on the part motor 3, and making the grinding head 21 on the grinding head motor 2 slightly contact a horizontal turning contour line of the nozzle, and the gap between the grinding head 21 and the side wall of the V-groove of the nozzle is between 0 and 0.05 mm;

[0032] 5) Starting the grinding head motor 2, the part motor 3 and the ultrasonic generator 4 to grind and polish the V-groove of the tungsten carbide nozzle semi-finished product;

[0033] 6) Closing the grinding head motor, the part motor and the ultrasonic generator to obtain a finished tungsten carbide nozzle.

[0034] As Figure 2 shown, in step 1), the top of the tungsten carbide drill bit 1 has a short cross edge 11 with an inclination angle; the edge length of the short cross edge is 0.2 mm, and the cutting edge is a three-order arc 12 that gradually decreases from the periphery to the center, so as to improve the continuity of cutting and make the chip removal smooth.

[0035] The gas-solid-liquid three-phase mixed polishing liquid in step 2) is composed of substances in three phases: solid, liquid, and gas. The liquid part uses a high-purity machine tool spindle cooling oil, which can not only act as the matrix of the polishing liquid but also quickly conduct the heat generated during polishing, keeping the polishing liquid between the grinding head and the nozzle in a stable liquid state instead of a rapidly evaporating or boiling state. The solid part uses single-crystal diamond micropowder with a particle size between 600 nm and 800 nm (nanometers), which acts as an abrasive during grinding.

[0036] The preparation steps of the gas-solid-liquid three-phase mixed polishing liquid are as follows: 2.1) Mix the cooling oil and the single-crystal diamond micropowder with a volume ratio of 5:1 to 6:1. If the solid part is too small, it will affect the grinding and polishing efficiency; if it is too much, the final polishing liquid will be too viscous, affecting the fluidity of the polishing liquid and thus the polishing effect. The particle size of the single-crystal diamond micropowder is between 600 nm and 800 nm. 2.2) After the cooling oil and the single-crystal diamond micropowder are mixed and stirred evenly according to the above ratio, put them into a nanoscale bubble generator to fully generate nanoscale bubbles in the solid-liquid mixture. It can be seen from the appearance that the color of the liquid changes significantly from light yellow to pale yellow, that is, white components appear in the color, indicating that sufficient bubbles have been generated, as Figure 3 shown.

[0037] In step 3), the grinding head motor 2, the part motor 3, and the ultrasonic generator 5 are all installed on the marble workbench 4, mainly to provide stable support, isolate the vibration from the surrounding environment, and absorb the vibration from the motor. In step 3), the included angle between the axis of the grinding head motor 2 and the axis of the part motor 3 is 165°, to ensure that the horizontal turning contour line of the grinding head 21 is parallel to the horizontal turning contour line of the V-groove. Then, any one of the part motor 3 or the grinding head motor 2 can be adjusted back and forth along its rotation center line until the grinding head slightly touches a horizontal turning contour line of the nozzle. At this time, the gap between the two parts is between 0 and 0.05 mm.

[0038] In step 5), the ultrasonic frequency of the ultrasonic generator is controlled between 40,000 Hz and 160,000 Hz, so that the amplitude of the grinding head is between 0.005 mm and 0.01 mm.

[0039] In step 6), the surface roughness of the V-groove of the tungsten steel nozzle finished product is within Ra 0.1 μm, and the contour tolerance is between 1 μm and 1.5 μm. After the polishing in step 6) is completed, first turn off the ultrasonic generator, then stop the grinding head motor, and then stop the part motor; retract the grinding head motor or the part motor to the workpiece installation position, and the workpiece cycle ends.

[0040] The processing and polishing in step 5) have the following action mechanisms: a) By using the ultrasonic vibration of the tool end face, the bubbles in the grinding fluid burst instantaneously, generating a huge impact force in a very small space, impacting the solid abrasives in the liquid, and hitting the surface of the workpiece to be polished. Without the grinding head contacting the nozzle, effective polishing of the nozzle can be achieved; since the grinding head does not directly contact the workpiece, the vibrations of the rotational movements of the grinding head and the workpiece will not be transmitted to the surface of the workpiece, thus avoiding the generation of vibration marks. B) Both the grinding head and the workpiece are performing rotational movements. Therefore, the contour error of the grinding head will not be reflected on the workpiece, while the contour error of the workpiece will be gradually corrected during the grinding and polishing process, thereby obtaining a V-groove surface with a surface roughness within Ra0.1um and a contour tolerance within 1um - 1.5um.

[0041] In summary, the technical solution of the present invention can fully and effectively achieve the above-mentioned invention purposes, and the structure and functional principles of the present invention have been fully verified in the embodiments, and can achieve the expected effects and purposes. Without departing from the principles and essence of the present invention, various changes or modifications can be made to the embodiments of the invention. Therefore, the present invention includes all replacement contents within the scope mentioned in the patent application scope, and any equivalent changes made within the patent application scope of the present invention fall within the scope of the patent applied for in this case.

Claims

1. A processing and polishing method for a tungsten steel nozzle, characterized in that, The steps include: (1) Using a tungsten carbide drill bit with a PCD coating on a CNC to process a tungsten carbide blank to form a semi-finished tungsten carbide nozzle with a V-groove; (2) Coating a gas-solid-liquid three-phase mixed polishing liquid in the V-groove of the tungsten carbide nozzle semi-finished product in step (1); (3) Separately installing a grinding head motor and a part motor on a substrate, and connecting an ultrasonic generator to the grinding head motor; (4) Clamping the tungsten carbide nozzle semi-finished product coated with the polishing liquid in step (2) on the part motor, making the grinding head on the grinding head motor slightly contact a horizontal turning contour line of the nozzle, and the gap between the grinding head and the side wall of the V-groove of the nozzle is between 0 and 0.05 mm; (5) Starting the grinding head motor, the part motor and the ultrasonic generator to grind and polish the V-groove of the tungsten carbide nozzle semi-finished product; (6) Closing the grinding head motor, the part motor and the ultrasonic generator to obtain a finished tungsten carbide nozzle.

2. The processing and polishing method of the tungsten steel nozzle according to claim 1, characterized in that: In step (1), the top of the tungsten carbide drill bit has a short cross edge with an inclination angle.

3. The processing and polishing method of the tungsten steel nozzle according to claim 2, characterized in that: The length of the short cross edge is 0.2 mm, and the cutting edge is a three-order arc that gradually decreases from the periphery to the center.

4. The processing and polishing method of the tungsten steel nozzle according to claim 1, characterized in that: The preparation steps of the gas-solid-liquid three-phase mixed polishing liquid in step (2) include: 2.1) Mixing cooling oil and single-crystal diamond micropowder with a volume ratio of 5:1 to 6:1; the particle size of the single-crystal diamond micropowder is between 600 nm and 800 nm; 2.2) After mixing and stirring the cooling oil and the single-crystal diamond micropowder according to the above volume ratio, putting them into a nanoscale bubble generator to fully generate nanoscale bubbles in the solid-liquid mixture.

5. The processing and polishing method of the tungsten steel nozzle according to claim 1, characterized in that: In step (3), the grinding head motor, the part motor and the ultrasonic generator are all installed on a marble workbench.

6. The processing and polishing method of the tungsten steel nozzle according to claim 1, characterized in that: In step (3), the included angle between the axis of the grinding head motor and the axis of the part motor is 165°.

7. The processing and polishing method of the tungsten steel nozzle according to claim 1, characterized in that: In step (5), the ultrasonic frequency is controlled between 40000 Hz and 160000 Hz, and the amplitude of the grinding head is between 0.005 mm and 0.01 mm.

8. The processing and polishing method of the tungsten steel nozzle according to claim 1, characterized in that: In step (6), the surface roughness of the V-groove of the finished tungsten carbide nozzle is within Ra0.1 μm, and the contour tolerance is between 1 μm and 1.5 μm.

9. The processing and polishing method of the tungsten steel nozzle according to claim 1, characterized in that: After the polishing in step (6) is completed, first turn off the ultrasonic generator, then stop the grinding head motor, and then stop the part motor; retract the grinding head motor or the part motor to the workpiece installation position, and the workpiece cycle ends.

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