CN112719825A

CN112719825A - Micro-milling and grinding composite PCD end mill and preparation method thereof

Info

Publication number: CN112719825A
Application number: CN202011538959.2A
Authority: CN
Inventors: 梁志强; 袁昊; 陈锐; 余政昊; 邢振路; 周天丰; 王西彬; 解丽静; 焦黎; 刘志兵
Original assignee: Beijing Institute of Technology BIT
Current assignee: Beijing Institute of Technology BIT
Priority date: 2020-12-23
Filing date: 2020-12-23
Publication date: 2021-04-30

Abstract

The invention discloses a micro milling and grinding composite PCD end mill and a preparation method thereof, belonging to the technical field of micro cutter processing. The end mill comprises a PCD part participating in cutting and a hard alloy part not participating in cutting, wherein the PCD part comprises an end blade, a cutter bottom, an end blade front cutter face, an end blade rear cutter face, a peripheral blade, a spiral groove and a peripheral blade rear cutter face, the rear angle of the end blade rear cutter face is 0 degrees, and the peripheral blade rear cutter face is a cylindrical surface with the same peripheral blade diameter. Traditional end sword, week sword structure are remained to this structure, realize the high efficiency of material through sharp cutting edge and get rid of, can full play PCD material surface diamond particle's grinding characteristic, obtain higher processingquality. Meanwhile, the preparation method of the PCD end mill is formed through high-frequency induction welding, laser turning and reducing machining and precise cutter grinding, can realize high-efficiency high-quality machining of the micro-milling composite PCD end mill, and can be used for high-quality micro-machining of various materials difficult to machine.

Description

Micro-milling and grinding composite PCD end mill and preparation method thereof

Technical Field

The invention relates to a micro milling and grinding composite PCD end mill and a preparation method thereof, belonging to the technical field of micro cutter processing.

Background

With the development of science and technology, the demand and the daily increase of high-precision tiny parts, more and more parts with complex tiny structural features appear. Meanwhile, in the aerospace industry, the automobile industry and the 3C industry, ceramic (zirconia) materials, titanium alloys, carbon fiber/metal matrix composite materials, high-silicon aluminum alloys, non-ferrous metals easy to adhere to cutters and the like are increasingly applied, and the materials generally easily cause cutter abrasion, and influence the machining efficiency, the machining quality and the like. The PCD milling cutter has remarkable advantages in the fine machining of tiny complex parts made of the materials, the cutter is good in wear resistance and high in cutting edge sharpness, and high machining quality can be obtained. With the continuous reduction of the characteristic size of the micro part, the wide application of the difficult-to-machine material and the continuous improvement of the machining quality requirement, the demand for the high-performance and high-precision micro PCD cutter is increased. The invention provides a micro milling and grinding composite PCD end mill and a preparation method thereof, aiming at the characteristics of realizing the high-quality processing requirement of a processed object and reducing the processing size.

Disclosure of Invention

The invention aims to provide a micro milling and grinding composite PCD end mill and a preparation method thereof, which are used for high-quality precision machining of difficult-to-machine materials.

The PCD part comprises an end blade, a cutter bottom, an end blade front cutter face, an end blade rear cutter face, a peripheral blade, a spiral groove and a peripheral blade rear cutter face, wherein the rear angle of the end blade rear cutter face is 0 degrees, namely any point on the end blade rear cutter face is positioned on the same horizontal plane with the end blade, and the peripheral blade rear cutter face is a cylindrical surface with the same diameter as the peripheral blade, namely a groove structure without cutting interference is arranged on the peripheral blade rear cutter face.

The equation of any point P on the cutting edge of the peripheral edge of the cutter is shown as the formula (1):

where r is a tool cutting radius, θ is an azimuth angle of any point P in a cross section, and β is a helix angle.

The design principle of the cutter structure is as follows: on one hand, the traditional end edge and peripheral edge structures are kept, and the material is efficiently removed through a sharp cutting edge; on the other hand, the design of the end cutting edge and the peripheral cutting edge flank can fully exert the grinding characteristics of the diamond particles on the surface of the PCD material, and obtain higher processing quality.

As another aspect of the present invention, a method for manufacturing the cutting tool is provided, which specifically includes the following steps:

step S1: preparing a cutter blank bar by a brazing mode, and welding a PCD composite sheet cylindrical block obtained by wire cutting on the accurately ground hard alloy bar by a high-frequency induction heating welding machine, wherein preferably, the welding technological parameters are that the welding diameter is 1-3mm, the welding temperature is 700 plus materials, the heat preservation time is 10-20s, and the welding pressure is 1-2MPa to obtain the PCD end mill blank bar;

step S2: the excircle turning and reducing processing of the blank bar is realized through a laser processing mode, preferably, picosecond laser is used, the laser power is 20-40W, the laser frequency is 500-plus-1000 kHz, the main shaft rotating speed is 500-plus-1000 r/min, the laser scanning speed is 0.05-0.2mm/s, and the back cutting depth is 1-3 mu m; the laser processing has no stress contact, so that the breaking phenomenon can be prevented while ensuring larger cutting amount, and then the PCD end mill cylindrical bar can be obtained;

step S3: because the size limit of the cylindrical bar obtained by laser processing in the step S2 exists, the complete preparation of the fine cutter under a certain size is difficult to realize, and meanwhile, certain defects exist in the laser processing surface and the cobalt-rich layer area of the material, if the stress concentration phenomenon is not removed, the service life of the cutter is reduced, so that the preparation of the fine PCD end mill by a precision grinding machine is realized, and the method mainly comprises the following steps: cylindrical grinding, end face grinding, groove grinding and cutter bottom grinding, preferably, the grinding speed is 10-30m/s, the grinding depth is 1-3 mu m, and the feeding speed is 5-25mm/min, and finally the fine PCD end mill is obtained.

The invention has the beneficial effects that:

(1) the structural design principle of the micro milling and grinding composite PCD end mill can fully utilize the grinding characteristics of PCD materials, and realize high-quality processing of difficult-to-process materials in processing modes such as groove milling, side milling, plane milling and the like.

(2) According to the preparation method, the efficient reducing processing of the blank bar can be realized through a laser processing method, then the high cutting edge quality is obtained through grinding processing, the high processing efficiency and the high cutting edge quality are obtained, meanwhile, the processing limit of the diameter of the cutter can be guaranteed, the micro PCD end mill is obtained, and the micro PCD end mill is finally used for high-quality micro processing of various difficult-to-process materials.

Drawings

The present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic structural view of a micro milling composite PCD end mill of the present invention;

wherein (a) is a schematic diagram of the whole structure of the cutter, (b) is a schematic diagram of the local structure of the cutter, and (c) is a schematic diagram of the section of the cutter;

FIG. 2 is a general flow chart of a method for manufacturing a cutting tool according to the present invention;

fig. 3 is a flowchart of the tool grinding process in step S3 according to the present invention.

Detailed Description

The technical solution of the present invention is further described in detail by the following embodiments.

The present example provides a micro-milling composite PCD end mill comprising a PCD part which participates in cutting and a cemented carbide part which does not participate in cutting, the overall structural design of which is shown in fig. 1 (a). Wherein the whole length L of the cutter is 50mm, the diameter D of the cutter handle is 3mm, the inclination angle alpha of the cutter neck is 20 degrees, the cutting diameter D is 0.2mm, and the cutting length L₁0.8mm, effective cutting length l₂0.5mm and a helix angle beta of 30 deg.. The PCD part comprises an end blade 1, a knife bottom 2, an end blade front knife face 3, an end blade rear knife face 4, a peripheral blade 5, a spiral groove 6 and a peripheral blade rear knife face 7, and the three-dimensional model design is shown in figure 1(b), wherein the rear angle of the end blade rear knife face 4 is 0 degrees, and the peripheral blade rear knife face 7 is a cylindrical surface with the same peripheral blade diameter.

As shown in fig. 2 to 3, this embodiment further provides a method for manufacturing the above fine milling and grinding composite PCD end mill, which specifically includes the following steps:

step S1: preparing a cutter blank bar by a brazing mode, and welding a PCD composite sheet cylindrical block obtained by linear cutting on the accurately-ground hard alloy bar by a high-frequency induction heating welding machine to obtain the PCD end mill blank bar. The welding diameter adopted in the embodiment is 2mm, the welding temperature is 750 ℃, the heat preservation time is 15s, and the welding pressure is 1.5 MPa;

step S2: and (3) realizing the excircle turning and reducing processing of the blank bar by a laser processing mode to obtain the PCD end mill cylindrical bar. The embodiment adopts a picosecond infrared solid laser to obtain a PCD cutter cylindrical bar with the front end diameter of 0.21mm, and the specific finish machining process comprises the steps of laser power of 22W, laser frequency of 800kHz, main shaft rotating speed of 1000r/min, laser scanning speed of 0.1mm/s and back cut amount of 1 mu m;

step S3: realize fine PCD end mill's sharpening preparation through the precision grinder, mainly include: the specific grinding process comprises cylindrical grinding, end face grinding, groove grinding and cutter bottom grinding, and is shown in figure 3. The grinding wheel used in the embodiment is a 2000# resident's friend cylindrical ceramic-based diamond grinding wheel, the machine tool used in the embodiment is a herdship six-axis numerical control tool grinding machine CNS7d, and the specific grinding process comprises the steps of grinding speed of 20m/s, grinding depth of 1 mu m and feeding speed of 8mm/min, and finally the milling and grinding composite PCD end mill with the diameter of 0.2mm is obtained.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.

Claims

1. A preparation method of a micro-milling and grinding composite PCD end mill is characterized by comprising the following steps:

(1) performing high-frequency induction heating welding on the PCD blank bar;

(2) performing laser turning and reducing processing on the excircle;

(3) and (5) precisely grinding the PCD cutter.

2. The method as claimed in claim 1, wherein in the PCD blank bar high frequency induction heating welding step, the cylindrical blocks of PCD compact obtained by wire cutting are welded on the refined hard alloy bar by a high frequency induction welding machine.

3. The method as claimed in claim 2, wherein the welding process parameters are welding diameter of 1-3mm, welding temperature of 700-800 ℃, holding time of 10-20s, and welding pressure of 1-2 MPa.

4. The method as claimed in any one of claims 1 to 3, wherein in the external circle laser turning diameter reduction processing step, picosecond laser is used, the laser power is 20-40W, the laser frequency is 500-1000kHz, the spindle rotation speed is 500-1000r/min, the laser scanning speed is 0.05-0.2mm/s, and the back cut amount is 1-3 μm.

5. The method of any one of claims 1 to 4, wherein the PCD cutter precision grinding step comprises: cylindrical grinding, end face grinding, groove grinding and cutter bottom grinding, wherein the grinding speed is 10-30m/s, the grinding depth is 1-3 mu m, and the feeding speed is 5-25mm/min, so that the micro milling and grinding composite PCD end mill is finally obtained.

6. A micro-milled composite PCD end mill prepared according to the method of any one of claims 1 to 5.

7. The end mill according to claim 6, wherein the end mill comprises a PCD part participating in cutting and a cemented carbide part not participating in cutting, the PCD part comprising an end edge, a bottom, an end edge rake face, an end edge relief face, a peripheral edge, a helical flute, and a peripheral edge relief face, wherein the relief angle of the end edge relief face is 0 ° and the peripheral edge relief face is a cylindrical face with the same peripheral edge diameter.

8. A PCD end mill according to claim 6 or 7, wherein the cutting diameter d is in the range 0.05 to 0.5 mm.

9. A PCD end mill according to any one of claims 6 to 8, wherein the equation for any point P on the peripheral cutting edge of the cutter is:

wherein r is the cutting radius of the cutter, theta is the azimuth angle of any point P in the cross section, and beta is the helical angle.