CN1789439A - High frequency pulse laser induced electrode directional discharging apparatus for roughing roller surface - Google Patents

Abstract

The invention discloses a texturing device for high repetition frequency pulse laser-induced electrode directional discharge on the surface of a roll. The two poles of the two poles are respectively connected to the roll to be processed and the discharge electrode, the discharge electrode is arranged near the laser focus of the laser generator, and there is a distance between the discharge electrode and the roll to be processed, and the control device controls The work of the pulse power supply and the high repetition frequency pulse laser generator. The device has good directivity, high working frequency, high power, and good controllability of texture distribution and uniformity.

Description

Texturing device for high repetition frequency pulse laser induced electrode directional discharge on roll surface

technical field

The invention relates to a surface processing equipment for metal materials.

Background technique

The surface of high-quality cold-rolled thin steel sheet requires a certain roughness profile to improve the formability and coating performance of the steel sheet. To produce high-quality cold-rolled sheets, the surface of the work rolls of the rolling mill must first be textured and shaped, and then the rolling mill uses the textured rolls to roll a cold-rolled textured sheet with the required roughness and shape. At present, the texturing technology of rolls includes shot peening (SBT), electric spark texturing (EDT), laser texturing (LT) and electron beam texturing (EBT). Steel grit is sprayed onto the surface of the roll at high speed, relying on the kinetic energy impact of the steel grit to plastically deform the surface of the roll to change the surface morphology; EDM texturing uses multiple pairs of electrodes to discharge and melt the roll surface in dielectric oil; laser roughening The CO 2 laser texturing technology is divided into two types. The CO ₂ laser texturing uses a high-speed rotating mechanical chopper to block the focused laser beam to form a pulsed laser, and melts and texturizes the roll surface. YAG laser texturing is to control the gain in the laser cavity through an acousto-optic Q-switching switch, thereby forming a high repetition frequency pulsed laser beam to texturize the roll surface, such as the patent application proposed by the applicant in 1992; electron beam texturing The electron beam is generated by an electron gun, and the surface of the roll is texturized through the focus of the magnetic lens. The texturing system and the roll must be processed in a vacuum environment. The above texturing methods can be divided into two types from the rough appearance of the surface texturing of the roll: random distribution texturing and controllable distribution texturing, shot peening texturing and electric spark texturing are uncontrollable Random distribution texturing, while laser texturing and electron beam texturing belong to controllable distribution texturing.

The randomly distributed texture of the roll is formed by the repeated impact of high-speed sand shot on the roll surface or the repeated discharge and fusion of multiple pairs of electrodes in the medium oil to the roll surface. Since the texturing process is uncontrollable, the effect of the roll surface is strengthened. The points often overlap, the roughness uniformity is poor, and there are a large number of connected fine grooves between the strengthening points, which is not conducive to the storage of lubricating oil and liquid under stress. When the sheet is formed, it is not conducive to the deformation and flow of the material. To some extent, it affects the deep drawing performance.

Controllable texturing of the roll surface by using laser beams and electron beams, since both the laser beam and the electron beams in the vacuum propagate in a straight line, with excellent directionality, under the control of the computer, the action position of each texturing point on the roll surface It can be precisely controlled, so the uniformity of the texturing roughness is good. At the same time, the textured points are evenly distributed isolated micro-pits, and each micro-pit stores oil and is not easy to lose, which can effectively reduce the friction coefficient and improve the performance of deep drawing and coating when the sheet is formed. Therefore, in the development and production of high-quality cold-rolled sheet, strip and foil, the controllable distributed texturing technology is showing more and more advantages. However, the controllable distribution texturing adopts single beam (or electron beam) texturing, and its texturing speed is not as fast as shot peening texturing and electric spark texturing (often using multiple pairs of electrode discharges). In particular, the acousto-optic Q switch necessary for high repetition frequency modulation of solid-state YAG laser texturing is limited by the drive power, and it is difficult to further increase the power of the laser texturing laser to meet the needs of higher-speed texturing and high-roughness texturing of rolls.

Contents of the invention

The object of the present invention is to provide a texturing device with high speed, good directivity, high operating frequency, high power, and good uniformity and controllability of texturing distribution on the roll surface, which can be induced by high-repetition-frequency pulsed laser-induced electrode directional discharge.

For achieving the above object, technical solution of the present invention is:

A texturing device for high repetition frequency pulse laser-induced electrode directional discharge on the surface of a roll. The device includes a pulse power supply, a high repetition frequency pulse laser generator, a discharge electrode, and a control device. The two poles of the pulse power supply are respectively connected to the rolls and discharge electrodes, the discharge electrodes are set close to the laser focus of the laser generator, and there is a gap between the discharge electrodes and the rolls to be processed, the control device controls the pulse power supply and the high The work of a repetition rate pulsed laser generator.

Further, the high repetition rate pulsed laser generator includes an acousto-optic drive power supply, a laser, a mirror, and a focusing lens connected in sequence, and the acousto-optic drive power supply is connected to the control device.

Further, the laser is an acousto-optic Q-switched YAG laser.

Further, the pulse power supply is a charge-discharge power supply, and the charge-discharge power supply circuit is composed of a high-voltage circuit and a low-voltage circuit connected in parallel.

Further, the negative electrode of the pulse power supply is connected to the discharge electrode, and the positive electrode is connected to the roll to be processed.

Further, the discharge electrodes are needle electrodes.

Further, the discharge electrode is a rotating electrode, and the rotating electrode includes a disk electrode and a driving device connected to the disk electrode, and the section of the circular arc edge of the disk electrode is pointed.

Further, the sharp angle is 20-30 degrees.

Further, the reflector is coated with an optical coating that allows visible light to pass through, and a camera is provided under the reflector, and the camera is connected to the control device.

Further, the device also includes a roll clamping mechanism. The roll clamping mechanism includes a rotating shaft, a guide rail, and a slide plate. The rotating shaft is fixed at one end of the guide rail. The slide plate matches the guide rail and can slide relative to the guide rail. The lens and discharge electrode are all fixed on the sliding plate, and the roll to be processed is fixed on the rotating shaft.

After the above-mentioned structure is adopted, since the roll surface roughening device includes a pulse power supply, a high repetition frequency pulse laser generator, a discharge electrode and a control device, under the control of the control device, the pulsed laser beam output by the pulse laser generator is focused to the Process the roll surface of the roll, so that the plasma plume is generated on the roll surface, and the discharge electrode is induced to discharge to the surface of the roll to be processed, forming a fusion spot. The invention retains the advantages of good directivity of the laser, good controllability of texturing distribution and uniformity, high operating frequency, and the discharge power of the discharge power supply can be increased according to needs, so the device achieves high texturing power and high frequency At the same time, it overcomes the problem of poor controllability, and the shortcomings of simple YAG laser texturization, such as low energy conversion efficiency and difficulty in increasing power. Experiments show that it is difficult to achieve 5.0 μm of roller surface roughness Ra after laser texturing and EDM texturing alone, but the high repetition frequency YAG laser-induced directional discharge texturing method of the present invention can make the roller surface roughness Ra within 1.5-14.0μm wide range controllable. In addition, the high-repetition-frequency pulse laser generator includes a reflector, and a CCD camera is arranged below the reflector, and the CCD camera is connected to the control device, so the image of the roll surface collected by the CCD camera will be Inputting into the computer can display and observe the topographic features of the roll surface, and can also be used to observe and adjust the position of the focusing lens relative to the roll surface, making the entire texturing process more controllable; In the process of high-frequency pulse laser induced discharge, due to the continuous rotation of the disc, each discharge acts on different points on the edge of the disc, which greatly reduces the overheating and ablation of the electrode tip caused by continuous discharge. The circumference of the disk replaces the tip of the needle-shaped electrode, so that the discharge point of the electrode extends from one point to the entire circumference line, which is equivalent to increasing the number of electrodes and reducing the heat accumulation on the electrode. At the same time, due to the large heat capacity of the disk, the disk The rotation of the roller accelerates the heat dissipation, thereby significantly improving the service life of the discharge electrode and making the texture of the roll more uniform. In addition, the charging and discharging power circuit is composed of a high-voltage circuit and a low-voltage circuit in parallel. The high-voltage circuit ensures that the voltage between the two electrodes is high enough to induce discharge breakdown, and the low-voltage circuit provides the large current required after breakdown.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the circuit structural diagram of pulse power supply of the present invention;

FIG. 3A is an effect diagram of the fusion spot obtained when the positive electrode is discharged;

Fig. 3B is an effect diagram of the fusion spot obtained when the negative electrode is discharged;

Figure 4A is a roll surface diagram obtained by simple YAG laser texturing in an atmospheric environment;

Fig. 4B is the roll surface diagram that the present invention texturing obtains under atmospheric environment;

Fig. 5 is a schematic diagram of the structure of the rotating electrode.

Detailed ways:

As shown in Figure 1, a high repetition frequency pulse laser induced electrode directional discharge texturing device on the surface of a roll, the device includes a pulse power supply 1, a high repetition frequency pulse laser generator 2, a discharge electrode 3, a control device 4 and a Roll 5, roll clamping mechanism 6;

The pulse power supply 1 is a fast charging and discharging power supply, the negative electrode is connected to the discharge electrode 3, and the positive electrode is connected to the roll 5 to be processed. There is a distance not greater than 1 mm between the discharge electrode 3 and the roll 5 to be processed. The gap is filled with air. The breakdown voltage between the rolls 5 to be processed is above 3000 volts, and the pulse inter-electrode voltage of the pulse power supply 1 is up to 500 volts, so as to ensure that there will be no automatic breakdown discharge between the discharge electrodes 3 and the rolls 5 to be processed. The discharge electrodes 3 are needle electrodes.

The pulse power supply 1 is a fast charging and discharging power supply, and its circuit structure is shown in Figure 2. In order to ensure that the laser can reliably induce discharge under high repetition frequency working conditions, the charging and discharging power supply circuit is composed of a high-voltage circuit and a low-voltage circuit in parallel. The function of the high-voltage circuit is to easily cause the induced discharge breakdown between the two electrodes, and the low-voltage circuit provides the large current required after the breakdown. In Figure 2, m and n are the input terminals of the two-phase power supply after low-voltage rectification, and the input voltage is 100- 500 volts, p and q are the input terminals after two-phase high-voltage rectification, the input voltage is 300-1000 volts, C1, IGBT1, and R1 are connected in series to form a low-voltage charging circuit to charge capacitor C2, and C2 passes through IGBT2. In the case of laser induction, Discharge to the surface of the roll 5 to be processed through the discharge electrode. C4, IGBT4, and R2 are connected in series to form a high-voltage charging circuit to charge capacitor C3, and C3, through IGBT3, discharges to the surface of the roll to be processed through the discharge electrode under laser induction. D3 is an isolation diode, D1 is a freewheeling diode, and R1 is a current limiting resistor. The control modules IGBT1, IGBT2, IGBT3, and IGBT4 are respectively connected to the control device 4, which is controlled by the control device 4 to trigger the opening. The opening time determines that the discharge pulse width can be adjusted within the range of 10 microseconds to 1 millisecond. Since the IGBT can operate at a frequency of 20KHZ Capacitors C2 and C3 are charged, so they can meet the requirements of high repetition frequency work.

The high repetition frequency pulse laser generator 2 includes an acousto-optic drive power supply 21, an acousto-optic Q-switched YAG laser 22, a mirror 23, and a focusing lens 24 connected in sequence; the discharge electrode 3 is located near the focus of the focusing lens 24.

In this embodiment, the control device 4 adopts a computer, and one end of the computer is connected to the acousto-optic drive power supply 21 and the YAG laser 22 in sequence. Under the control of the computer, the acousto-optic drive power supply 21 provides switching signals for the acousto-optic switch in the laser 22, so that The laser 22 sends out high repetition rate laser pulses; the downstream of the output end of the laser 22 is provided with a mirror 23 and a focusing lens 24 in turn, the mirror 23 is a total reflection mirror, and the pulsed laser beam with a wavelength of 1.06 μm output by the laser 4 passes through the total reflection mirror 23 After reflection, it is focused on the roll surface of the roll to be processed 5 by the focusing lens 24, so that the irradiated part on the roll surface produces a plasma plume 7, and the plasma plume 7 plays the role of an induced discharge switch; Plated with an optical coating, the light of visible light wavelength can be made to pass through, and a CCD camera 8 is arranged below the reflecting mirror 23, and the CCD camera 8 is connected to a computer, so the image of the roll surface collected by the CCD camera 8 Image input into the computer can display and observe the topographic features of the roll surface, and can also be used to observe and adjust the position of the focusing lens 24 relative to the roll surface; the other end of the computer is connected to the pulse power supply 1 to control the rapid charging and discharging process of the power supply 1 ;

After the discharge electrode is discharged thousands of times, the tip of the electrode will be severely ablated and deformed due to overheating, so that the laser-induced discharge cannot be effectively performed. To avoid this situation, the discharge electrode 3 adopts a rotating electrode as shown in Figure 5, including a circular Disc electrode 31, rotating shaft 32, and motor 34. The disc electrode 31 is a disc with a diameter of about 100-160 mm and a thickness of 5-10 mm. The disk electrode 31 is processed by steel, copper and its alloys or other ablation-resistant conductive metal materials. The center of the disk electrode 31 has a hole, and is installed on the rotating shaft 32 through the hole, and is closely connected with the rotating shaft 32. Cooperate, rotating shaft 32 is made of conductive metal material, and grooved pulley 35 is equipped with at one end, and disk electrode 31, rotating shaft 32, motor 34, pulley 35 are installed on the bracket 36 that insulating material is made by bearing, and motor 34 passes through The drive belt 37 on the belt pulley 35 drives the disk electrode 31 to rotate, and the rotating speed of the disk electrode 31 can be regulated by the power supply; 38 is used to communicate with the pulse power supply 1, and the brush plate 38, the rotating shaft 32, and the disc electrode 31 form a conductive channel connected to an output pole of the pulse power supply 1, and the other output pole of the pulse power supply 1 is connected to the roll 5 to be processed. A slight gap is maintained between the edge of the disk electrode 31 and the roll 5 to be processed.

In addition, the rotating shaft 32 can also be connected to the motor 34 through other transmission devices, and the motor 34 drives the disk electrode 31 to rotate.

The roll clamping mechanism 6 is a processing machine tool. The machine tool includes a rotating shaft 61, a guide rail 62, and a sliding plate 63. The rotating shaft 61 is fixed on one end of the guiding rail 62. The sliding plate 63 matches the guiding rail 62 and can slide along the guiding rail. Mirror 23, focusing lens 24, and discharge electrode 3 are all fixed on the sliding plate 63, and the roll 5 to be processed is fixed on the rotating shaft 61 and can rotate together with the rotating shaft 61, while the reflecting mirror 23, focusing lens 24, and discharging electrode 3 are all fixed on the rotating shaft 61. Fixed on the slide plate 63, through the translation of the slide plate 63 relative to the axis of the roll to be processed 5, the processing of the surface of the roll to be processed 5 is completed under the rotation of the roll to be processed 5 and the translational movement of the focusing lens 24 and the discharge electrode 3.

When the discharge electrode and the roll surface are discharged in the atmospheric environment, with the extension of the discharge current pulse width, the diameter of the discharge channel will expand due to thermal effects, causing the diameter of the molten spot on the roll surface to become larger and the smoothness of the contour to deteriorate. In order to reduce this influence, negative electrode discharge is adopted in the device of the present invention, even if the discharge electrode 3 is connected to the negative electrode of the pulse power supply 1, and the roll to be processed 5 is connected to the positive electrode of the power supply, the effect of the fusion spot obtained when the positive electrode discharge is shown in Fig. 3A Figure 3B shows the effect diagram of the fusion spot obtained when the negative electrode is discharged.

4A and 4B respectively show the roll surface images obtained by simple YAG laser texturing and high repetition frequency YAG laser-induced directional discharge texturing of the present invention in an atmospheric environment. Under the same laser parameter conditions, the surface roughness Ra of simple laser texturing is 2.0 μm, while the surface roughness Ra of high repetition frequency laser-induced directional discharge texturing is 10 μm.

The above-mentioned device can not only be used for surface roughening of rolls, steel, non-ferrous metallurgical cold-rolled sheets and other processes, but also can be used for surface roughening and strengthening of hot rolls with harsh working conditions, and can also be used for group hole processing, welding, and heat treatment of metals. or other surface treatment techniques.

Claims (10)

1, a kind of texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge, it is characterized in that: this device comprises the pulse power, high recurrent frequency pulse laser producer, discharge electrode, control device, the two poles of the earth of the described pulse power connect described roll to be processed and discharge electrode respectively, described discharge electrode is arranged at the laser spot place near described laser generator, and leave spacing between described discharge electrode and the roll to be processed, described control device is controlled the work of the described pulse power and described high recurrent frequency pulse laser producer.

2, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 1, it is characterized in that: described high recurrent frequency pulse laser producer comprises acousto-optic drive power, laser apparatus, speculum, the condenser lens that connects successively, and described acousto-optic drive power is connected with described control device.

3, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 2 is characterized in that: described laser apparatus is the YAG laser apparatus of sound-optical accent Q.

4, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 1 is characterized in that: the described pulse power is for discharging and recharging power supply, and this discharges and recharges electric power loop is that a high tension loop and a low tension loop are formed in parallel.

5, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 1 is characterized in that: described pulse power negative pole connects described discharge electrode, the described roll to be processed of anodal connection.

6, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 1 is characterized in that: described discharge electrode is a needle electrode.

7, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 1, it is characterized in that: described discharge electrode is a rotating electrode, this rotating electrode comprises disk electrode and the drive unit that is connected with disk electrode, and described disk electrode arc edge section is an angular shape.

8, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 7 is characterized in that: described wedge angle is the 20-30 degree.

9, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 2, it is characterized in that: be coated with the optical coating that can make visible light transmissive on the described speculum, be provided with stylus below described speculum, this stylus connects described control device.

10, the texturing device of roller surface high recurrent frequency pulse laser induction electrode directional discharge as claimed in claim 2, it is characterized in that: this device also comprises the roll clamping device, this roll clamping device comprises turning axle, guide rail, slide carriage, turning axle is fixed in guide rail one end, slide carriage is complementary with guide rail and can slides by relative guide rail, described speculum, condenser lens, discharge electrode all are fixed on the slide carriage, and roll to be processed is fixed on the turning axle.

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