CN108296633B - Laser water jet machining device and application thereof - Google Patents

Abstract

The invention relates to a laser water jet processing device and its application. The processing device comprises a laser emitting device and a laser head connected thereto. The laser head comprises a spray head, a rotating disc, a separation base and a connecting seat which are coaxially connected in sequence, A laser through hole is coaxially connected to the center of the nozzle, the rotating disc and the separation base, and the laser through hole is communicated with the laser transmission hole of the connecting seat. A first water flow channel is formed in the nozzle, and is installed on the first water flow channel The water sprinkler has a second water flow channel in the rotating plate, the gap between the rotating plate and the separation base forms a third water flow channel, a fourth water flow channel is formed in the separation base, and an outer wall of the separation base is formed with The water inlet is provided with a plurality of auxiliary gas inlet holes in the connecting seat. The invention can realize more efficient cutting, the water jet can quickly cool the material in the cutting process, and the water jet does not need a high-precision device, greatly reducing the cost of the device and being conducive to realizing industrialization.

Description

Laser water jet processing device and its application

technical field

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

Background technique

Polycrystalline cubic boron nitride (PCBN) is a new type of material compounded by many small cubic boron nitride (CBN) single crystals under high temperature and high pressure through a binder. It is another new type of superhard after artificial diamond. synthetic material. It has excellent characteristics such as high hardness and wear resistance, thermal stability and chemical inertness, low friction coefficient and good thermal conductivity. Therefore, it has been widely used in the tool industry, and its appearance has opened up broad prospects for the cutting of ferrous metals and hard and tough materials. Although diamond is the hardest material, diamond tools also have limitations, because its chemical properties are not stable enough, and it is easy to react with ferrous iron to form iron carbide. Due to the thermal instability of diamond, the hardness will not be as high as it should be at high temperature. effect. The cutting methods of PCBN generally include diamond grinding wheel cutting, wire EDM, high pressure water jet cutting, ultrasonic processing and laser cutting.

The diamond grinding wheel cutting method is simple, but the processing quality is poor and the product qualification rate is low. Due to the poor electrical conductivity of CBN particles, wire EDM is difficult to process, and the wire is easily broken, making it difficult to achieve high-efficiency EDM cutting of PCBN. Then some scientists improved the machinability of PCBN wire EDM by adding additives with good conductivity and increasing the pressure during the sintering process of PCBN, but it can only achieve small batch production and production, which restricts the wide application of this technology. application. Water cutting has a high cost of use and requires a lot of water and sand; sandblasting abrasives contain pathogenic free silicon, which pollutes the production environment and has high maintenance costs; cutting carbon steel plates is easy to rust, which affects the appearance of products. Ultrasonic machining is a special machining that uses ultrasonic frequency as a tool for small amplitude vibration, and through the hammering effect of the abrasive free in the liquid between it and the workpiece on the surface to be machined, the surface of the workpiece material is gradually broken. Drilling of hard and brittle materials, such as glass, quartz, ceramics, silicon, germanium, ferrite, gemstones and jade, etc. The harder the material or the greater the strength and toughness, the more difficult it is to process, and it needs to be combined with other processing methods. . Laser cutting uses a high power density laser beam to irradiate the material to be cut, so that the material is quickly heated to the vaporization temperature, and evaporates to form holes. , to complete the cutting of the material. The advantages are ① high material utilization rate: the minimum slit width can be 0.1mm, generally in the range of 0.1 ~ 0.3mm; ② small heat affected zone: generally in the range of 0.1 ~ 0.15mm, the workpiece deformation is small; ③ good cutting section quality ; ④ Fast cutting speed and high efficiency; ⑤ No tool wear and compensation problems, but there are still some defects in laser cutting PCBN, such as the formation of recast layer, the incision needs to be subjected to secondary grinding, and the material removal rate is low, melting The material cannot be cooled in time and adheres to the PCBN material again, resulting in long processing time, large energy consumption, and low efficiency.

At present, the most common method of laser cutting is pulsed laser cutting, but it is easy to form a recast layer, and the incision needs to be subjected to secondary grinding. The hardness and brittleness of ceramics lead to low material removal rate and slow speed, high energy consumption, and the melted material cannot be timely. It cools and adheres to the PCBN material again. Due to these shortcomings of pulsed laser, this patent makes some improvements to it, changing the structure and mechanism of laser cutting, so that it can achieve better cutting of PCBN.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a fast, cheap and low energy consumption laser water jet processing device and its application.

The technical scheme adopted by the present invention to solve the technical problem is:

A laser water jet processing device includes a laser emitting device and a laser head connected thereto, the laser head comprises a spray head, a rotating disc, a separation base and a connecting seat which are coaxially connected in sequence, and the spray head, the rotating disc and the separation base are The center of the seat is coaxially connected with a laser through hole, and the laser through hole is communicated with the laser penetration hole of the connecting seat. A first water flow channel is formed in the nozzle. There is a second water flow channel that communicates with the first water flow channel. The gap between the rotating disc and the separation base forms a third water flow channel. Two O-shaped water sealing rings are installed on both sides of the third water flow channel. The bearing is connected with the separation base, and a fourth water flow channel is formed in the separation base, and the fourth water flow channel is communicated with the third water flow channel. A plurality of auxiliary gas inlet holes are formed in the seat, the auxiliary gas inlet holes are connected with the laser transmission hole in the center of the connecting seat, and the end face of the nozzle is formed with a laser, auxiliary gas outlet and water outlet.

Moreover, install a water pressure gauge on the water pipe connected to the water inlet outside the laser head.

Moreover, an auxiliary gas pressure gauge is installed on the gas pipe connected to the auxiliary gas inlet outside the laser head.

Moreover, the laser emitting device is carbon dioxide laser, Nd:YAG laser, fiber laser, preferably carbon dioxide laser.

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

The application of a laser water jet processing device in PCBN processing. Using carbon dioxide laser, the auxiliary gas pressure is 50-70KPa, the laser power is 400-900W, the wavelength of the laser continuous wave is 1.06-10.6μm, the rated power of the water jet laser head is 1-2kW, the water jet pressure is 4.5-6MP, The line 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 cutting at 1-6mm intervals during the cutting process.

This patent is to cut PCBN by laser water jet. The cutting principle is to cut PCBN by first laser heating and subsequent water jet quenching. The laser beam irradiates the surface of the sample to convert the bonding of PCBN from sp ² to sp ^3. Materials The atomic structure of the transforms from cubic (cBN) to hexagonal (hBN), resulting in changes in the stress field and surrounding material.

The advantages and positive effects of the present invention are:

The mechanism of laser water jet cutting PCBN is the residual stress caused by temperature gradient and phase transformation, which makes the material propagate cracks along the incision direction, so that the depth of the incision is deepened, and more efficient cutting can be achieved, thereby providing a fast, cheap and low energy consumption. The method of cutting PCBN. The water jet can quickly cool (quench) the material during the cutting process, and the water jet does not require a high-precision device, which greatly reduces the cost of the device and is conducive to industrialization.

Description of drawings

Fig. 1 is the structural schematic diagram of the laser head of the present invention;

Fig. 2 is the left side view of Fig. 1;

Fig. 3 is the deformation zone of the workpiece and the cutting path diagram;

Fig. 4 is the depth and width diagram of workpiece conversion area;

Figure 5 is a side view of the incision;

Figure 6 is a top view of a cutout;

Fig. 7 is the scanning electron microscope image of the top view of cutting sample with the line energy of 5.9kJ/m;

8 is a cross-sectional view of a sample cut with a line energy of 23.6 J/mm.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only descriptive, not restrictive, and cannot limit the protection scope of the present invention.

A laser water jet processing device includes a laser emitting device and a laser head connected to it. The laser head includes a spray head 1, a rotating disk 2, a separation base 8 and a connecting seat 9 that are coaxially connected in sequence. The center of the disc and the separation base are coaxially connected with a laser through hole 7, which is communicated with the laser transmission hole 10 of the connecting seat. A first water flow channel 15 is formed in the nozzle, and water is installed on the first water flow channel. The spray head 14 has a second water flow channel 13 connected to the first water flow channel in the rotating disk. The gap between the rotating disk and the separation base forms a third water flow channel 12. Two water flow channels are installed on both sides of the third water flow channel. Road O-ring water seal 3. The rotating disc is connected with the separation base through the bearing 4, a fourth water flow channel 5 is formed in the separation base, the fourth water flow channel is communicated with the third water flow channel, and the outer wall of the separation base is made with a fourth water flow channel. Water inlet 6. A plurality of auxiliary gas inlet holes 11 are formed in the connection seat, and the auxiliary gas inlet holes are communicated with the laser transmission hole in the center of the connection seat.

A laser and auxiliary gas outlet 16 and a water outlet 17 are formed on the end face of the shower head.

The laser emitting device is a carbon dioxide laser.

The water enters from the water inlet and 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 nozzle in sequence, and then is ejected from the water outlet.

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

Install a water pressure gauge on the water pipe connected to the water inlet outside the laser head, and install an auxiliary gas pressure gauge on the gas pipe connected to the auxiliary gas inlet.

In this example, a carbon dioxide laser is used to cut PCBNs with different thicknesses by laser water jet to carry out two groups of different experiments for comparison. Both groups of experiments use a laser continuous wave with a wavelength of 10.6 μm, and the rated power of the two groups of experimental water jet laser heads are both It is 1.5kW, water jet assisted laser to cut PCBN. First, the material is locally heated by the laser beam of the water jet laser head, and then rapidly quenched by the water jet to rapidly cool the PCBN, so as to realize the cutting of the PCBN.

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

Table 1

In the experiment, the laser beam was focused on the sample surface through a 127mm focal length lens, and the focusing spot was 0.2mm. During the experiment, the pressure of the compressed air around the laser beam was kept at 69 kPa to protect the focusing lens from damage caused by splashes generated during the cutting process. Due to the high absorption of laser energy by water, the water jet lags behind the laser cutting at about 2mm intervals during the cutting process, absorbing the laser power by directly contacting the water.

Figure 3 shows the deformation zone and cutting path of the workpiece. The size of the deformation zone in the XZ plane is smaller than the length along the laser path. Figure 4 is a model of the strain state of the material, giving the transition depth and transition width annotations to obtain the XZ stress field plane.

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

For Experiment 1 cut PCBN samples, the fracture characteristics of PCBN obtained by observation are summarized in Table 2. At high line energy (23.6 J/mm), the PCBN samples were completely cut and separated, indicating that the energy input above the threshold could be completely cut apart. At the midline energy (11.8J/mm), the PCBN has an obvious groove along the cutting route, and the material can be completely separated by cutting the sample by hand pressure, resulting in a clean section and an intuitive crack interface, indicating that this level of The energy and cut thickness thresholds are comparable. Only at the lowest line energy (5.9J/mm), only a shallow groove can be observed on the surface of the sample. After the cutting is completed, pressure is applied to the groove by hand, and the sample cannot be separated, indicating that the energy of this level is lower than that of cutting Thickness threshold.

The sample was cut with a cutting line energy of 5.9 J/mm, and the SEM image of the top view of the sample was obtained as shown in Figure 7. Due to the rapid heat dissipation of the water, a relatively narrow incision was produced, and the observation found that the depth of the incision was relatively shallow, and the entire material was not completely cut. Only a shallow groove was observed, and no visible transverse cracks were generated during the cutting process. . The cross-sectional view of the sample obtained by cutting the sample with a cutting line energy of 23.6J/mm is shown in Figure 8. The laser beam can only cut to the deformation zone in the figure, and the fracture zone below acts on the fracture zone through the conduction of stress in the deformation zone. , so as to complete the laser water jet cutting of the material.

Experiment 2 The surface deformation of the cutting experiment PCBN, through the observation of the cutting results of the three cutting parameters, the surface of the sample is all a groove. At the same time, it was found that the PCBN surface profile was distributed almost symmetrically with respect to the incision, and it was also observed that the incision width of the three scribed grooves was roughly equal to the laser beam diameter of 0.2 mm. The deformation is highest near the cut surface and decreases monotonically with the groove distance, so the magnitude of the surface deformation depends on the line energy and increases with the line energy.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept, several modifications and improvements can be made, which belong to the present invention. protected range.

Claims (8)

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.

Images