CN108296633B

CN108296633B - Laser water jet machining device and application thereof

Info

Publication number: CN108296633B
Application number: CN201810051791.9A
Authority: CN
Inventors: 赵静楠; 司学康; 郭健; 马晓磊
Original assignee: Tianjin University of Science and Technology
Current assignee: Tianjin University of Science and Technology
Priority date: 2018-01-19
Filing date: 2018-01-19
Publication date: 2020-02-21
Anticipated expiration: 2038-01-19
Also published as: CN108296633A

Abstract

The invention relates to a laser water jet machining device and application thereof, wherein the machining device comprises a laser emitting device and a laser head connected with the laser emitting device, the laser head comprises a spray head, a rotating disc, a separating base and a connecting seat which are coaxially connected in sequence, the centers of the spray head, the rotating disc and the separating base are coaxially communicated with each other to form a laser through hole, the laser through hole is communicated with a laser through hole of the connecting seat, a first water flow channel is formed in the spray head, a water spray head is installed on the first water flow channel, a second water flow channel is formed in the rotating disc, a third water flow channel is formed in a gap between the rotating disc and the separating base, a fourth water flow channel is formed in the separating base, a water inlet is formed in the outer wall of the separating base, and a plurality of auxiliary gas inlet holes. The invention can realize more efficient cutting, the water jet can rapidly cool the material in the cutting process, and the water jet does not need a high-precision device, thereby greatly reducing the cost of the device and being beneficial to realizing industrialization.

Description

Laser water jet machining device and application thereof

Technical Field

The invention belongs to the field of hard and brittle material processing, relates to laser processing, and particularly relates to a laser water jet processing device and application thereof.

Background

Polycrystalline Cubic Boron Nitride (PCBN) is a novel material formed by compounding a plurality of fine Cubic Boron Nitride (CBN) single crystals through a binder at high temperature and high pressure, and is a novel super-hard synthetic material following artificial diamond. Has the excellent characteristics of higher hardness, higher wear resistance, higher thermal stability, higher chemical inertness, lower friction coefficient, better thermal conductivity and the like. Therefore, the cutting tool is widely applied to the cutter industry, and the appearance of the cutting tool opens up wide prospects for the cutting processing of ferrous metals and hard and tough difficult-to-process materials. Although diamond is the hardest material, diamond cutters are limited because it is chemically unstable and reacts readily with ferrous iron to form iron carbide, and because of the thermal instability of diamond, hardness at high temperatures plays an undesirable role. The cutting method of PCBN generally includes diamond wheel cutting, wire electrical discharge machining, high-pressure water jet cutting, ultrasonic machining, laser cutting, and the like.

The method is characterized in that a diamond grinding wheel cutting method is simple, but the machining quality is poor, the product percent of pass is low, wire breakage is very easy due to poor electrical conductivity of CBN particles in wire electrical discharge machining, the machinability of the wire electrical discharge machining of the PCBN is improved by adding an additive with good electrical conductivity and a method for increasing pressure in the sintering process of the PCBN, but small-batch manufacturing and production can be realized, so that the wide application of the technology is limited, the water cutting use cost is high, a large amount of water sand is needed, a sand blasting grinding material contains pathogenic free silicon, the production environment is polluted greatly, the maintenance cost is high, a cutting carbon steel plate is easy to rust and the product appearance is influenced, the ultrasonic machining is a tool with small amplitude vibration by using ultrasonic frequency, the hammering effect of the grinding material which is free from liquid to a machined surface through the grinding material between the sand blasting material and the workpiece is high, the special machining for gradually crushing the surface of the workpiece is mainly used for machining of various hard and brittle materials with holes, such as glass, quartz, ceramic, silicon, germanium, ferrite, jeweler, jade, a kerf material, a cutting material is formed by a small-cutting energy consumption, a high intensity or a high-cutting strength, a cutting material is increased, a kerf material is formed by a small-cutting process-resistant laser beam-forming process, a laser beam-melting process-forming process, the heat-cutting process is performed when the laser beam-melting-cutting process is performed within a high-resistant cutting-less-melting process-less-resistant cutting-less-loss-less-loss-caused-in-caused-loss-in-caused-loss-caused-in-caused-to-caused-in-.

The current common method for laser cutting is pulse laser cutting, but a recast layer is easily formed, secondary honing is needed for cutting, the hardness and brittleness of the ceramic cause low material removal rate, low speed and high energy consumption, and the melted material cannot be cooled in time and adheres to the PCBN material again. Because of the defects of the pulse laser, the patent improves the pulse laser, and changes the structure and the mechanism of laser cutting to realize better cutting of PCBN.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a rapid, cheap and low-energy-consumption laser water jet machining device and application thereof.

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

a laser water jet processing device comprises a laser emitting device and a laser head connected with the laser emitting device, wherein the laser head comprises a spray head, a rotating disc, a separating base and a connecting base which are coaxially connected in sequence, a laser through hole is coaxially communicated with the centers of the spray head, the rotating disc and the separating base, the laser through hole is communicated with a laser penetrating hole of the connecting base, a first water flow channel is arranged in the spray head, a water spray head is installed on the first water flow channel, a second water flow channel communicated with the first water flow channel is arranged in the rotating disc, a third water flow channel is formed by a gap between the rotating disc and the separating base, two O-shaped water sealing rings are installed on two sides of the third water flow channel, the rotating disc is connected with the separating base through a bearing, a fourth water flow channel is arranged in the separating base, the fourth water flow channel is communicated with the third water flow channel, a water inlet communicated with the fourth water flow channel is arranged on the outer wall of the, a plurality of auxiliary gas inlet holes are formed in the connecting seat, the auxiliary gas inlet holes are communicated with the laser permeation hole in the center of the connecting seat, and a laser and auxiliary gas outlet and a water outlet are formed in the end face of the spray head.

And a water pressure meter is arranged on a water pipe which is connected with a water inlet outside the laser head.

And an auxiliary gas pressure gauge is arranged on a gas pipe which is connected with an auxiliary gas inlet outside the laser head.

The laser emitting device is a carbon dioxide laser, a Nd: YAG laser, a fiber laser, preferably a carbon dioxide laser.

An application of a laser water jet processing device in processing hard and brittle materials. The hard and brittle material comprises cubic boron nitride, polycrystalline cubic diamond, boron carbide, titanium nitride and titanium diboride.

An application of a laser water jet machining device in PCBN machining. A carbon dioxide laser is adopted, the auxiliary gas pressure is 50-70KPa, the laser power is 400-900W, the wavelength of laser continuous waves is 1.06-10.6 mu m, the rated power of water jet laser heads is 1-2kW, the water jet pressure is 4.5-6MP, and the linear energy is 5.9-37.8J/mm. The auxiliary gas adopts compressed air, nitrogen, helium and oxygen. Compressed air is preferred. The water jet lags the laser cut at 1-6mm intervals during the cutting process.

This patent is through laser water jet cutting PCBN, and its cutting principle is that laser heating earlier and water jet quenching collaborative work after with cuts PCBN, and the laser beam shines to the sample surface, makes PCBN's bonding follow sp from sp²To sp³The transformation, the atomic structure of the material transforms from cubic (cBN) to hexagonal (hBN), resulting in a stress field and surrounding material changes.

The invention has the advantages and positive effects that:

the mechanism of laser water jet cutting of PCBN is residual stress caused by temperature gradient and phase change, so that the material propagates cracks along the direction of the notch, the depth of the notch is deepened, more efficient cutting can be realized, and the method for cutting PCBN is rapid, low in cost and low in energy consumption. The water jet can rapidly cool (quench) the material in the cutting process, and does not need a high-precision device, thereby greatly reducing the cost of the device and being beneficial to realizing industrialization.

Drawings

FIG. 1 is a schematic structural view of a laser head according to the present invention;

FIG. 2 is a left side view of FIG. 1;

FIG. 3 is a diagram of a deformation zone and a cutting path of a workpiece;

FIG. 4 is a depth and width map of a workpiece transition zone;

FIG. 5 is a cut-away side view;

FIG. 6 is a top view of the slit;

FIG. 7 is a scanning electron microscope image of a top view of a cut sample at a linear energy of 5.9 kJ/m;

FIG. 8 is a cross-sectional view of a sample cut at a linear energy of 23.6J/mm.

Detailed Description

The present invention will be described in further detail with reference to the following embodiments, which are illustrative only and not limiting, and the scope of the present invention is not limited thereby.

The utility model provides a laser water jet processingequipment, includes laser emitter and rather than the laser head of being connected, the laser head including coaxial coupling's shower nozzle 1 in proper order, rolling disc 2, separation base 8 and connecting seat 9, at the shower nozzle, the coaxial intercommunication system in center of rolling disc and separation base has laser through-hole 7, this laser through-hole and the laser of connecting seat pass through hole 10 intercommunication, the system has first water runner 15 in the shower nozzle, install water shower nozzle 14 on first water runner, the system has the second water runner 13 with first water runner intercommunication in the rolling disc, clearance between rolling disc and the separation base forms third water runner 12, install twice O shape water sealing ring 3 in the both sides of third water runner. The rotating disc is connected with the separation base through a bearing 4, a fourth water flow channel 5 is formed in the separation base and communicated with the third water flow channel, and a water inlet 6 communicated with the fourth water flow channel is formed in the outer wall of the separation base. A plurality of auxiliary gas inlet holes 11 are formed in the connecting base and are communicated with the laser penetration hole at the center of the connecting base.

The end face of the nozzle is provided with a laser and auxiliary gas outlet 16 and a water outlet 17.

The laser emitting device is a carbon dioxide laser.

Water enters from the water inlet and sequentially passes through the fourth water flow channel, the third water flow channel, the second water flow channel, the first water flow channel and the water spray head and then is sprayed out from the water outlet.

The auxiliary gas enters from the auxiliary gas inlet hole on the connecting seat and is mixed with the carbon dioxide working gas, and then the mixture is ejected from the laser and auxiliary gas outlets through the laser through hole.

A water pressure meter is arranged on a water pipe which is connected with a water inlet outside the laser head, and an auxiliary gas pressure meter is arranged on a gas pipe which is connected with an auxiliary gas inlet.

This embodiment adopts the carbon dioxide laser, and the PCBN that laser water jet cutting thickness is different carries out two sets of different experiments and compares, and two sets of experiments all use the wavelength of laser continuous wave to be 10.6 mu m, and the rated power of two sets of experiment water jet laser heads all is 1.5kW, and the supplementary laser of water jet cuts PCBN. Firstly, the material is locally heated by the laser beam of the water jet laser head, and then the PCBN is rapidly cooled by the rapid quenching of the water jet so as to realize the cutting of the PCBN.

Two experiments were carried out for comparison with different sizes of test pieces, and samples containing 82% CBN, 18% ALN and the like (average particle size 15 μm) were used for the materials. The water jet pressure of the two experiments is 4.5-6MP, the roughness (mum) of the polished surface is 0.3, the roughness (mum) of the polished surface is 3, and the speed (mm/s) of the polished surface is 21.2, 42.4 and 63.5 respectively. The side length of the regular triangle material with the test piece size (mm) in experiment 1 is 7mm, the thickness is 1.6mm, the laser power of the laser water jet is 400-500W, and the corresponding linear energy (J/mm) is 23.6, 11.8 and 5.9 respectively. The test piece size (mm) of experiment 2 is 50 mm of the diameter of the cylindrical material and 4.8 of the thickness, the laser power of the laser water jet is 700-900W, and the corresponding linear energy (J/mm) is 5.9-37.8.

TABLE 1

In the experiment, a laser beam is focused on the surface of a sample through a 127mm focal length lens, and the focusing spot is 0.2 mm. The pressure of compressed air surrounding the laser beam was maintained at 69kPa during the experiment to protect the focusing lens from damage to the lens due to spatter generated during the cutting process. Since water can absorb laser energy very high, the water jet lags behind the laser cut by an interval of about 2mm during cutting, absorbing the laser power by direct contact with water.

Fig. 3 shows the deformation zone and the cutting path of the workpiece, the size of the deformation zone in the XZ plane being smaller than the length along the laser path. Fig. 4 is a model of the strain state of a material, with transition depth and transition width designations given to obtain the stress field plane for XZ.

Fig. 5 shows a cross-sectional view of a plane strain fracture of a cut material with the crack propagation direction down, which is also the direction of force propagation. FIG. 6 is a top view of the cut material showing the direction and depth of the laser cut channel crack.

The fracture characteristics of PCBN obtained by observation for the PCBN cut samples of experiment 1 are summarized in table 2. At high linear energy (23.6J/mm), the PCBN sample completely cut apart, indicating that energy input above the threshold can completely cut apart. At a mid-line energy (11.8J/mm), PCBN had a distinct groove along the cutting path, and the material was completely separated by hand pressure cutting the sample, resulting in a clean cross-section and a visual crack interface, indicating that this level of energy was comparable to the cut thickness threshold. Only at the lowest linear energy (5.9J/mm) was a shallow groove observed on the sample surface, and after the cut was completed and pressure was applied to the groove by hand, the sample could not be separated, indicating that this level of energy was below the cut thickness threshold.

The sample was cut with a cutting line energy of 5.9J/mm and a scanning electron micrograph of the top view of the sample was obtained as shown in FIG. 7. Due to the rapid heat dissipation of water, a relatively narrow cut is generated, and the observation shows that the depth of the cut is shallow, all materials are not completely cut, only a shallow groove can be observed, and no visible transverse crack is generated in the cutting process. The cross section of the sample obtained by cutting the sample with the cutting line energy of 23.6J/mm is shown in FIG. 8, the laser beam can only cut the deformation zone in the figure, and the lower fracture zone acts on the fracture zone through the stress conduction of the deformation zone, thereby completing the laser water jet cutting of the material.

Experiment two cutting experiment PCBN's surface deformation, through the observation to three cutting parameter cutting results, the sample surface all is a recess. While the PCBN surface profile was found to be almost symmetrically distributed relative to the cuts, it was also observed that the width of the cuts of the three scribed grooves was approximately equal to the laser beam diameter of 0.2 mm. The deformation is highest near the notch surface and decreases monotonically with groove distance, so the magnitude of the surface deformation is dependent on the line energy and increases with increasing line energy.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept, and these changes and modifications are all within the scope of the present invention.

Claims

1. The utility model provides a laser water jet processingequipment, includes laser emitter and rather than the laser head of being connected which characterized in that: the laser head comprises a spray head, a rotating disc, a separating base and a connecting base which are coaxially connected in sequence, wherein the centers of the spray head, the rotating disc and the separating base are coaxially communicated and provided with a laser through hole, the laser through hole is communicated with a laser permeation hole of the connecting base, a first water flow passage is arranged in the spray head, a water spray head is arranged on the first water flow passage, a second water flow passage communicated with the first water flow passage is arranged in the rotating disc, a third water flow passage is formed by a gap between the rotating disc and the separating base, two O-shaped water sealing rings are arranged on two sides of the third water flow passage, the rotating disc is connected with the separating base through a bearing, a fourth water flow passage is arranged in the separating base and communicated with the third water flow passage, a water inlet communicated with the fourth water flow passage is arranged on the outer wall of the separating base, a plurality of auxiliary gas inlet holes are arranged in the connecting base, and are communicated with the laser permeation hole in the center of the connecting base, the end face of the spray head is provided with a laser and auxiliary gas outlet and a water outlet, a water pressure gauge is arranged on a water pipe which is connected with the water inlet outside the laser head, and an auxiliary gas pressure gauge is arranged on a gas pipe which is connected with the auxiliary gas inlet outside the laser head.

2. The laser water jet machining apparatus according to claim 1, wherein: the laser emitting device is a carbon dioxide laser, an Nd-YAG laser and a fiber laser.

3. Use of the laser water jet machining device according to claim 1 for machining hard and brittle materials.

4. Use according to claim 3, characterized in that: the hard and brittle material is cubic boron nitride or polycrystalline cubic diamond or boron carbide or titanium nitride or titanium diboride.

5. Use of a laser waterjet machining apparatus according to claim 1 in PCBN machining.

6. Use according to claim 5, characterized in that: a carbon dioxide laser is adopted, the auxiliary gas pressure is 50-70KPa, the laser power is 400-900W, the wavelength of laser continuous waves is 1.06-10.6 mu m, the rated power of water jet laser heads is 1-2kW, the water jet pressure is 4.5-6MP, and the linear energy is 5.9-37.8J/mm.

7. Use according to claim 6, characterized in that: the auxiliary gas adopts compressed air, nitrogen, helium and oxygen.

8. Use according to claim 6, characterized in that: the water jet lags the laser cut at 1-6mm intervals during the cutting process.