CN117737350A - Vertical incidence type double-beam variable-speed laser heat treatment method - Google Patents
Vertical incidence type double-beam variable-speed laser heat treatment method Download PDFInfo
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000010791 quenching Methods 0.000 claims abstract description 53
- 230000000171 quenching effect Effects 0.000 claims abstract description 49
- 230000008569 process Effects 0.000 claims abstract description 16
- 230000001360 synchronised effect Effects 0.000 claims abstract description 11
- 230000008859 change Effects 0.000 claims abstract description 9
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 7
- 238000007493 shaping process Methods 0.000 claims description 13
- 230000001276 controlling effect Effects 0.000 claims description 12
- 230000001105 regulatory effect Effects 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 8
- 238000012544 monitoring process Methods 0.000 claims description 8
- 230000009466 transformation Effects 0.000 claims description 4
- 229910001339 C alloy Inorganic materials 0.000 claims description 3
- 229910001141 Ductile iron Inorganic materials 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 3
- 230000009977 dual effect Effects 0.000 claims description 3
- 239000010959 steel Substances 0.000 claims description 3
- 238000007669 thermal treatment Methods 0.000 claims 1
- 238000005496 tempering Methods 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 4
- 238000003491 array Methods 0.000 description 6
- 238000000265 homogenisation Methods 0.000 description 4
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
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- 235000000621 Bidens tripartita Nutrition 0.000 description 1
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
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Abstract
The invention provides a vertical incidence type double-beam variable-speed laser heat treatment method, which comprises the following steps: setting a double-beam interval regulation and control scheme and a working distance regulation and control scheme, carrying out synchronous laser quenching scanning on two tooth surfaces of the tooth to be processed by utilizing two linear light spots output by a double-beam laser heat treatment processing head, carrying out double-beam interval regulation and control and working distance regulation and control while carrying out laser quenching scanning, and carrying out temperature closed-loop control to ensure that the surface quenching temperature of a double-beam irradiation area is controlled in an austenite phase change area. The invention uses the homogenized double light beams with adjustable light spot length, adopts a vertical incidence mode to carry out lap joint-free and synchronous laser scanning quenching on two tooth surfaces of one tooth of the gear part, can thoroughly eliminate the problems of lap joint/back tempering softening effect and interference between the laser light beams and adjacent teeth in the laser quenching process of the gear, and realizes the uniform hardening treatment of the tooth surfaces of the gears with multiple sizes to be strengthened.
Description
Technical Field
The invention belongs to the field of laser heat treatment, and particularly relates to a vertical incidence type double-beam variable-speed laser heat treatment method.
Background
The gear is used as an important part for transmitting torque and bearing transmission in the speed reducer, and has higher surface hardness and better core toughness, so that the gear with strong outer and tough inner is often required to be subjected to surface strengthening treatment. At present, a speed reducer manufacturer generally carries out carburizing and quenching treatment on a gear, immerses a part in a heating medium containing a carbon source, enables carbon atoms to permeate from the medium to the surface of the part in a high-temperature environment, and forms a hard and wear-resistant carbonized layer through rapid cooling. Considering the problems of long production period, low surface hardness, uneven depth of hardened layer, unstable quality and the like of the chemical heat treatment processes such as carburization/nitridation and the like, the existing laser quenching technology is limited by the tooth shape of the gear, and the laser beam can interfere with the adjacent tooth during the laser scanning of the whole tooth surface.
The patent with application number 202011400095.8 proposes a gear laser quenching method and device for continuously and uniformly hardening a gear tooth surface by utilizing rectangular light spots to perform continuous laser quenching treatment, and continuously and uniformly hardening the gear tooth surface is obtained by adjusting the scanning speed in the laser scanning process. The patent with the application number of 202210014405.5 carries out laser quenching on the carburized and quenched low-carbon steel gear tooth surface, simultaneously sprays inactive cooling gas on the other tooth surface which is being scanned, and the hardness of the treated gear surface reaches or even exceeds the hardness of the traditional carburization treatment, and has the advantages of small quenching deformation, high surface neatness and the like. However, the above patent has the following problems in quenching gears: 1) When the small-modulus gear is subjected to laser quenching, a single laser scans the tooth surface in sequence, so that the problem of back tempering is often caused; 2) The spot size is not matched with the tooth surface, after the laser quenching of the whole tooth surface is finished, a periodical softening area exists in a hardening layer, and the hardening layer cannot be suitable for the laser quenching treatment of the gears with multiple specifications; 3) During laser scanning, the light beam is vertical to the tooth surface, and can interfere with adjacent teeth in a certain scanning range.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a vertical incidence type double-beam variable-speed laser heat treatment method; the vertical incidence type double-beam variable-speed laser heat treatment method utilizes the homogenized double beams with adjustable light spot length, adopts a vertical incidence mode to carry out lap joint-free and synchronous laser scanning quenching on two tooth surfaces of one tooth of a gear part, can thoroughly eliminate the problems of lap joint/back tempering softening effect and interference between laser beams and adjacent teeth in the laser quenching process of gears, and realizes the uniform hardening treatment of the tooth surfaces of the gears with multiple sizes to be strengthened.
The invention is realized by the following technical scheme:
a vertical incidence type double-beam variable-speed laser heat treatment method comprises the following steps:
(1) According to parameters of the gear to be processed, determining the length of the linear light spot, wherein the length of the linear light spot can completely cover the tooth width of the gear to be processed; the variation range of the linear light spot in the length direction is 10-60 mm, and the dimension in the width direction is 0.1mm;
(2) The double-beam laser heat treatment processing head is arranged on the mechanical arm, so that two linear light spots output by the double-beam laser heat treatment processing head are focused on two sides of a tooth top of a gear to be processed, and the length of each linear light spot meets the requirement of the step (1);
the double-beam laser heat treatment processing head comprises a collimating mirror, a spectroscope, a reflecting mirror and two shaping focusing systems, wherein the shaping focusing systems comprise a first micro-lens array, a second micro-lens array, a focusing mirror, a beam combining mirror, a pyrometer, a parallel flat plate, a motor and an encoder; the laser beam is collimated by the collimating mirror and then forms a parallel beam, the parallel beam is incident to the spectroscope and is divided into two mutually perpendicular laser beams by the spectroscope, one laser beam is horizontally incident to the first shaping focusing system along the original direction, the other laser beam is vertically incident to the reflecting mirror, and the two laser beams are horizontally incident to the second shaping focusing system after being reflected by the reflecting mirror, so that two parallel beams are formed; the two parallel beams are uniformly shaped in the length direction of the light spot through the first micro lens array, the second micro lens array and the focusing lens, the uniformly shaped beams are incident to the parallel flat plate through the beam combining lens, and finally are converged on the two side processing inclined surfaces in a linear light spot mode; the pyrometer and the beam combining lens are coaxially arranged, the motor is used for controlling the inclination angle of the parallel flat plate, and the encoder is used for monitoring the rotation angle of the parallel flat plate in real time;
(3) Setting a double-beam interval regulation scheme, namely changing the interval between two lateral line light spots in real time by adjusting the angle of a parallel flat plate, so that the interval is equal to the tooth thickness of the tooth to be processed at different tooth height positions;
(4) Setting a working distance regulating and controlling scheme, namely adjusting the working distance of the double-beam laser heat treatment processing head in real time through a mechanical arm to compensate the defocusing amount so as to ensure that double beams are always focused on a processing tooth surface in the laser scanning process;
(5) Synchronous laser quenching scanning is carried out on two tooth surfaces of the tooth to be processed by utilizing two linear light spots output by the double-beam laser heat treatment processing head, double-beam distance regulation and control and working distance regulation are carried out while laser quenching scanning is carried out, and temperature closed-loop control and variable-speed scanning are carried out so as to ensure that the surface quenching temperature of a double-beam irradiation area is controlled in an austenite phase change area; the scanning direction is perpendicular to the length direction of the light spot, and the scanning path is perpendicular to the tooth width direction of the gear;
(6) After the double-beam laser quenching of one tooth is completed, the gear is rotated, two linear light spots output by the double-beam laser heat treatment processing head are focused on two sides of the tooth top of the next tooth, the steps (3) - (5) are repeated, and the double-beam laser quenching treatment is carried out on the next tooth until the laser quenching of all teeth is completed.
Further, the length of the light spot in the step (1) is 0.3-1.5mm longer than the tooth width.
Further, in the step (2), the incident angle of the two laser beams is kept unchanged all the time, and the included angle between the laser beams and the tooth surface is 25-40 degrees.
Further, the temperature closed-loop control process in the step (5) is as follows: and monitoring real-time temperature data of at least two positions of the tooth surfaces at two sides in the linear light spot irradiation area by using a pyrometer, regulating and controlling laser power in real time according to the temperature measured by the tooth surfaces at two sides, wherein the temperature of the light spot irradiation area is in an austenite phase transformation area, and reducing the surface temperature by reducing the laser power when the surface temperature exceeds the upper limit of a preset temperature threshold.
Further, if a scanning area with the tooth thickness being more than or equal to 25mm exists in the step (5), the scanning area is subjected to variable speed scanning treatment, namely the scanning speed is reduced to 75-95% of the initial speed, so that the surface temperature rapidly reaches the preset lower temperature limit.
Further, in the step (5), the temperature of the light spot irradiation area is 50-150 ℃ above Ac3 for the gear material of the medium-low carbon alloy steel, and 40-200 ℃ above Ac1 for the gear material of the spheroidal graphite cast iron.
The invention has the following beneficial effects:
(1) According to the invention, when the laser quenching treatment is carried out on the tooth surface of the gear by adopting a scanning mode of vertical incidence of double light beams, the laser is prevented from interfering with the incident laser in the scanning range from the tooth top to the tooth bottom, the processing flexibility is improved, and the processing area with larger tooth thickness is matched with variable speed scanning, so that the uniform depth of the hardened layer is obtained. By regulating and controlling the technological parameters, the hardening effect of the laser normal incidence tooth surface quenching can be achieved.
(2) Based on the micro-lens array homogenization principle and combining with the imaging characteristics of a parallel flat plate, the invention obtains double light beams with adjustable spot sizes and intervals on two sides and uniform energy through the precise regulation and control of the micro-lens array intervals and the rotation angles of the parallel flat plate, so that the spot sizes on two sides cover tooth widths, the spot intervals are adapted to the tooth thicknesses at different positions, the continuous full-area laser quenching treatment of tooth surfaces is realized, and the lap tempering softening problem existing in the traditional laser quenching technology is solved.
(3) The invention utilizes the beam splitting prism to split a beam of collimated light into two paths of light with almost equal energy, the two paths of parallel light are subjected to homogenization shaping and offset through the micro lens array and the parallel flat plate, two homogenization line light spots with adjustable size and interval are obtained, synchronous laser scanning is carried out on two tooth surfaces of one tooth of the gear, the back tempering problem existing in the traditional laser quenching process of the gear is solved, and the method for cooperatively processing two lasers is replaced. By utilizing different beam splitting prisms, one laser beam is hopefully split into a plurality of sub-beams with equal energy, so that synchronous laser heat treatment at a plurality of positions is realized.
Drawings
Fig. 1 is a schematic structural view of a dual beam laser thermal processing head.
Detailed Description
As shown in fig. 1, the invention provides a dual-beam laser heat treatment processing head, which comprises a collimating lens 1, a spectroscope 2, a reflecting mirror 3 and two shaping focusing systems, wherein the shaping focusing systems comprise a first micro lens array 4, a second micro lens array 5, a focusing lens 6, a beam combining lens 7, a pyrometer 8, a parallel flat plate 9, a motor 10 and an encoder 11.
The laser beam is collimated by the collimator lens 1 and then forms a parallel beam, the parallel beam is incident to the spectroscope 2, and is divided into two beams of light with approximately equal energy by the spectroscope 2, wherein one beam of laser is incident to the first shaping focusing system along the original direction, and the other beam of laser is incident to the second shaping focusing system after being reflected by the reflector lens 3, so that two parallel beams are formed. Then, the two parallel beams are homogenized and shaped in the length direction of the light spot through the first micro lens array 4, the second micro lens array 5 and the focusing mirror 6, and the homogenized double beams are incident to the parallel flat plate 9 through the beam combining mirror 7 and finally converged on the two side processing inclined surfaces in the form of linear light spots. The beam combining lens 7 can not only high-transmit the double-beam laser, but also high-reflect the infrared light, the pyrometer 8 and the beam combining lens 7 are coaxially arranged, and the real-time temperature detection is carried out along with the movement of the irradiation area of the double beams, so that a temperature closed-loop control system is formed. The motor 10 is used for controlling the inclination angle of the parallel plate 9, and is connected with the encoder 11 behind the motors at the two sides, so as to monitor the rotation angle of the parallel plate 9 in real time.
The invention further provides a vertical incidence type double-beam variable-speed laser heat treatment method based on the double-beam laser heat treatment processing head, which comprises the following steps:
(1) According to parameters of the gear to be processed, determining the length of the linear light spot, wherein the length of the linear light spot can completely cover the tooth width of the gear to be processed; the variation range of the linear light spot in the length direction is 10-60 mm, and the dimension in the width direction is fixed to be 0.1mm. The spot length is preferably 0.3-1.5mm longer than the tooth width during actual processing.
The invention regulates the size of the linear light spot based on the micro lens array homogenization principle. A continuous laser with a Gaussian light source is selected, an incident Gaussian beam is divided into two parallel double beams with approximately equal energy paths through a spectroscope 2 and a reflecting mirror 3 after being collimated, and the two parallel beams are sequentially incident into a micro-lens array homogenizing focusing system to be homogenized and shaped along the length direction of a linear light spot, and are converged on a focal plane along the optical axis direction through a cylindrical focusing mirror to form the linear light spot with uniformly distributed energy.
The length of the linear light spot is related to parameters (including focal length and unit width) of the micro lens array, the distance between the micro lens arrays and the focal length of the focusing lens, and the light spot size is regulated by changing the distance between the micro lens arrays. Wherein the first microlens array 4 is controlled to move by a motor through a guide rail, and the second microlens array 5 is fixed. The focal length of the micro lens array is 20-45 mm, the unit width is 0.5-2.6 mm, the thickness is 2mm, and the maximum value of the distance between two micro lenses is not more than 2 times of the focal length of the micro lenses.
(2) And (2) mounting the double-beam laser heat treatment processing head on the mechanical arm, so that two linear light spots output by the double-beam laser heat treatment processing head are focused on two sides of the tooth top of the gear to be processed, and the length of each linear light spot meets the requirement of the step (1). Preferably, the incidence angle of the two laser beams is kept unchanged all the time, and the included angle between the laser beams and tooth surfaces with different specifications is usually 25-40 degrees.
(3) And setting a double-beam interval regulation scheme, namely changing the interval between two lateral line light spots in real time, so that the interval is equal to the tooth thickness of the tooth to be processed at different tooth height positions. The pitch between the linear light spots is realized by controlling the inclination angle of the parallel flat plates 9 through the motor 10, the adjustable range of the inclination angle of the parallel flat plates 9 is-50 degrees to 50 degrees, the variation range of the pitch of the light spots is 2-20 mm after the inclination angle of the parallel flat plates 9 at two sides is adjusted, the plane of the parallel flat plates 9 is 0 degrees when being perpendicular to the optical axis, the parallel flat plates 9 at two sides simultaneously rotate inwards by one, and simultaneously rotate outwards by plus. In the process of controlling the rotation of the parallel flat plate 9 by the motor 10, the rotation angle and the rotation direction of the motor 10 are monitored in real time through the encoder 11, so that the symmetry of laser scanning positions at two sides is ensured. The center thickness of the parallel plate 9 is less than or equal to 6mm, the wedge angle is determined according to the designed distance range of the light spots and the rotatable angle of the parallel plate 9, and in order to ensure the uniformity of the light spots, the wedge angle is not excessive and is generally less than or equal to 15 degrees. The symmetry of the angular deviation of the parallel plates 9 on both sides is less than 0.1mm, and when the motor 10 drives the parallel plates 9 to rotate, the rotation angle error of both sides is not more than 0.1 degrees.
(4) And setting a working distance regulating and controlling scheme, namely, adjusting the working distance of the double-beam laser heat treatment processing head in real time through a mechanical arm to compensate the defocusing amount so as to ensure that double beams are always focused on a processing tooth surface in the laser scanning process. Preferably, the error between the movement amount of the laser processing head and the compensation defocus amount is controlled to be not more than 0.05mm.
(5) The method comprises the steps of utilizing two linear light spots output by a double-beam laser heat treatment processing head to synchronously perform laser quenching scanning on two tooth surfaces of a tooth to be processed, performing double-beam interval regulation and working distance regulation while performing laser quenching scanning, and performing temperature closed-loop control to ensure that the surface quenching temperature of a double-beam irradiation area is controlled in an austenite phase transformation area. The scanning direction is perpendicular to the length direction of the light spot so as to ensure the lap-free laser quenching treatment of the double tooth surfaces. The scan path is in a direction perpendicular to the tooth width of the gear, and the scan sequence may be along the tooth tip-tooth root or along the tooth root-tooth tip.
The temperature closed-loop control process comprises the following steps: real-time temperature data of at least 2 positions (1 position of each single-side tooth surface laser irradiation area) in an online light spot irradiation area are monitored by utilizing a pyrometer 8, and the real-time temperature data are used as judgment basis of closed-loop control and are used for formulating temperature closed-loop control under a double-beam laser scanning strategy. According to the temperature measured by the tooth surfaces at two sides, the laser power and the scanning speed are regulated and controlled in real time, and the temperature of a light spot irradiation area is in a certain interval of an austenite phase transformation area aiming at different gear materials, and when the surface temperature exceeds the upper limit of a preset temperature threshold, the surface temperature is reduced by reducing the laser power. If a scanning area with the tooth thickness of more than or equal to 25mm exists, the scanning area is subjected to variable speed scanning treatment, namely the scanning speed is reduced (75-95% of the initial speed is adopted), so that more heat accumulation effect is obtained in the light spot irradiation area. The scanning speed is obtained by combining the lifting speed of the laser head and the offset speed of the light beam, so that the scanning speed is regulated and controlled by simultaneously controlling the lifting speed and the offset speed of the light beam during speed changing. The dual-beam laser irradiation area subjected to temperature closed-loop control and variable-speed scanning can be stably kept in a preset temperature interval, so that the uniformity of the depth of a hardening layer is improved.
The austenitic phase transition temperatures of different gear materials are different, the temperature of a light spot irradiation area is 50-150 ℃ above Ac3 for the gear materials of medium-low carbon alloy steel, and the temperature of the light spot irradiation area is 40-200 ℃ above Ac1 for the gear materials of spheroidal graphite cast iron.
(6) After the double-beam laser quenching of one tooth is completed, the gear is rotated, two linear light spots output by the double-beam laser heat treatment processing head are focused on two sides of the tooth top of the next tooth, the steps (3) - (5) are repeated, and the double-beam laser quenching treatment is carried out on the next tooth until the laser quenching of all teeth is completed.
Example 1
(1) A40 Cr standard straight-tooth cylindrical gear with the modulus of 3 and the tooth width of 9.7mm is selected. According to the gear parameter information obtained by processing, the distance between the micro lens arrays is controlled by a motor through a guide rail, so that the light spot length is 10mm (the light spot length is 0.3mm longer than the tooth width);
(2) The double-beam laser processing head is arranged on the six-axis robot, a path program is written through a robot control handle, and light spots are focused at tooth tops;
(3) The motor rotates the parallel plates to adjust the distance between two light spots, the symmetry degree of the angle deviation of the parallel plates at two sides is less than 0.1mm, the deflection angle at one side is 30-50 degrees, and the distance change range of the two light spots is 2-6 mm;
(4) According to the change of the distance between the two light beams, the working distance of the laser processing head is controlled by a robot to compensate the defocusing amount, so that the two light beams are always focused on a processing tooth surface in the laser scanning process;
(5) The austenitizing temperature of 40Cr is 850 ℃. The position (1 part of each unilateral tooth surface) of the irradiation area 2 is subjected to real-time temperature monitoring through a coaxial pyrometer. Reducing the laser power when the surface temperature of the laser irradiation area is higher than 950 ℃; when the surface temperature of the laser irradiation region is lower than 900 ℃, the laser power is increased. The surface temperature of the irradiation region subjected to closed-loop control is 50-100 ℃ above austenitizing temperature (Ac 1);
(6) After quenching of one tooth is completed, the gear is rotated by a certain angle, and the steps (3) - (5) are repeated to quench the next tooth until the heat treatment processing of all the teeth is completed;
the embodiment realizes synchronous laser heat treatment of two tooth surfaces simultaneously by utilizing double-beam laser quenching, wherein the consistency deviation of the surface hardness of the two tooth surfaces is less than or equal to 2HRC, and the consistency of the depth of a treatment layer is more than or equal to 95 percent.
Example 2
(1) A40 Cr standard straight-tooth cylindrical gear with the modulus of 7 and the tooth width of 24mm is selected. According to the gear parameter information obtained by processing, the distance between the micro lens arrays is controlled by a motor through a guide rail, so that the light spot length is 24.7mm (the light spot length is 0.7mm longer than the tooth width);
(2) The double-beam laser processing head is arranged on the six-axis robot, a path program is written through a robot control handle, and light spots are focused at tooth tops;
(3) The motor rotates the parallel plates to adjust the distance between two light spots, the symmetry degree of the angle deviation of the parallel plates at two sides is less than 0.1mm, the deflection angle at one side is 20-47 degrees, and the distance change range of the two light spots is 3-9 mm;
(4) According to the change of the distance between the two light beams, the working distance of the laser processing head is controlled by a robot to compensate the defocusing amount, so that the two light beams are always focused on a processing tooth surface in the laser scanning process;
(5) The austenitizing temperature of 40Cr is 850 ℃. The position (1 part of each unilateral tooth surface) of the irradiation area 2 is subjected to real-time temperature monitoring through a coaxial pyrometer. Reducing the laser power when the surface temperature of the laser irradiation region is higher than 965 ℃; when the surface temperature of the laser irradiation region is lower than 910 ℃, the laser power is increased. The surface temperature of the irradiation area subjected to closed-loop control is 60-115 ℃ above austenitizing temperature (Acl);
(6) After quenching of one tooth is completed, the gear is rotated by a certain angle, and the steps (3) - (5) are repeated to quench the next tooth until the heat treatment processing of all the teeth is completed;
the embodiment realizes synchronous laser heat treatment of two tooth surfaces simultaneously by utilizing double-beam laser quenching, wherein the consistency deviation of the surface hardness of the two tooth surfaces is less than or equal to 2HRC, and the consistency of the depth of a treatment layer is more than or equal to 95 percent.
Example 3
(1) A40 Cr standard straight-tooth cylindrical gear with the modulus of 16 and the tooth width of 35mm is selected. According to the gear parameter information obtained by processing, the distance between the micro lens arrays is controlled by a motor through a guide rail, so that the light spot length is 36mm (the light spot length is longer than the tooth width by 1 mm);
(2) The double-beam laser processing head is arranged on the six-axis robot, a path program is written through a robot control handle, and light spots are focused at tooth tops;
(3) The motor rotates the parallel plates to adjust the distance between two light spots, the symmetry degree of the angle deviation of the parallel plates at two sides is less than 0.1mm, the deflection angle at one side is-20-30 degrees, and the distance between the two light spots is 7-15 mm;
(4) According to the change of the distance between the two light beams, the working distance of the laser processing head is controlled by a robot to compensate the defocusing amount, so that the two light beams are always focused on a processing tooth surface in the laser scanning process;
(5) The austenitizing temperature of 40Cr is 850 ℃. The position (1 part of each unilateral tooth surface) of the irradiation area 2 is subjected to real-time temperature monitoring through a coaxial pyrometer. Reducing the laser power when the surface temperature of the laser irradiation area is higher than 985 ℃; when the surface temperature of the laser irradiation region is lower than 920 ℃, the laser power is increased. The surface temperature of the irradiation region subjected to closed-loop control is 70-135 ℃ above austenitizing temperature (Ac 1); a control program is written by a robot handle, so that the scanning speed of the double light beams in the scanning range of the tooth thickness of more than or equal to 25mm is 95% of the initial speed;
(6) After quenching of one tooth is completed, the gear is rotated by a certain angle, and the steps (3) - (5) are repeated to quench the next tooth until the heat treatment processing of all the teeth is completed.
The embodiment realizes synchronous laser heat treatment of two tooth surfaces simultaneously by utilizing double-beam laser quenching, wherein the consistency deviation of the surface hardness of the two tooth surfaces is less than or equal to 2HRC, and the consistency of the depth of a treatment layer is more than or equal to 95 percent.
Example 4
(1) A40 Cr standard straight-tooth cylindrical gear with the modulus of 20 and the tooth width of 58.5mm is selected. According to the gear parameter information obtained by processing, the distance between the micro lens arrays is controlled by a motor through a guide rail, so that the light spot length is 60mm (the light spot length is 1.5mm longer than the tooth width);
(2) The double-beam laser processing head is arranged on the six-axis robot, a path program is written through a robot control handle, and light spots are focused at tooth tops;
(3) The motor rotates the parallel plates to adjust the distance between two light spots, the symmetry degree of the angle deviation of the parallel plates at two sides is less than 0.1mm, the deflection angle at one side is-50-10 degrees, and the distance between the two light spots is changed within 13-20 mm;
(4) According to the change of the distance between the two light beams, the working distance of the laser processing head is controlled by a robot to compensate the defocusing amount, so that the two light beams are always focused on a processing tooth surface in the laser scanning process;
(5) The austenitizing temperature of 40Cr is 850 ℃. The position (1 part of each unilateral tooth surface) of the irradiation area 2 is subjected to real-time temperature monitoring through a coaxial pyrometer. Reducing the laser power when the surface temperature of the laser irradiation area is higher than 1000 ℃; when the surface temperature of the laser irradiation region is lower than 930 ℃, the laser power is increased. The surface temperature of the irradiation region subjected to closed-loop control is 80-150 ℃ above austenitizing temperature (Ac 1); a control program is written by a robot handle, so that the scanning speed of the double light beams in the scanning range of the tooth thickness of more than or equal to 25mm is 75% of the initial speed;
(6) After quenching of one tooth is completed, the gear is rotated by a certain angle, and the steps (3) - (5) are repeated to quench the next tooth until the heat treatment processing of all the teeth is completed.
The embodiment realizes synchronous laser heat treatment of two tooth surfaces simultaneously by utilizing double-beam laser quenching, wherein the consistency deviation of the surface hardness of the two tooth surfaces is less than or equal to 2HRC, and the consistency of the depth of a treatment layer is more than or equal to 95 percent.
It will be obvious to those skilled in the art that the present invention may be varied in a number of ways without departing from the scope of the invention. All such modifications as would be obvious to one skilled in the art are intended to be included within the scope of this claims.
Claims (6)
1. A vertical incidence type double-beam variable-speed laser heat treatment method is characterized by comprising the following steps:
(1) According to parameters of the gear to be processed, determining the length of the linear light spot, wherein the length of the linear light spot can completely cover the tooth width of the gear to be processed; the variation range of the linear light spot in the length direction is 10-60 mm, and the dimension in the width direction is 0.1mm;
(2) The double-beam laser heat treatment processing head is arranged on the mechanical arm, so that two linear light spots output by the double-beam laser heat treatment processing head are focused on two sides of a tooth top of a gear to be processed, and the length of each linear light spot meets the requirement of the step (1);
the double-beam laser heat treatment processing head comprises a collimating lens (1), a spectroscope (2), a reflecting mirror (3) and two shaping focusing systems, wherein the shaping focusing systems comprise a first micro-lens array (4), a second micro-lens array (5), a focusing lens (6), a beam combining lens (7), a pyrometer (8), a parallel flat plate (9), a motor (10) and an encoder (11); the laser beam is collimated by the collimating mirror (1) and then forms a parallel beam, the parallel beam is incident to the spectroscope (2), the spectroscope (2) divides the parallel beam into two mutually perpendicular laser beams, one laser beam is horizontally incident to the first shaping focusing system along the original direction, the other laser beam is vertically incident to the reflecting mirror (3), and the other laser beam is horizontally incident to the second shaping focusing system after being reflected by the reflecting mirror (3), so that two parallel beams are formed; the two parallel beams are homogenized and shaped in the length direction of a light spot through a first micro lens array (4), a second micro lens array (5) and a focusing mirror (6), the homogenized beams are incident to a parallel flat plate (9) through a beam combining mirror (7), and finally are converged on two side processing inclined planes in a linear light spot mode; the pyrometer (8) and the beam combining lens (7) are coaxially arranged, the motor (10) is used for controlling the inclination angle of the parallel flat plate (9), and the encoder (11) is used for monitoring the rotation angle of the parallel flat plate (9) in real time;
(3) Setting a double-beam interval regulation scheme, namely changing the interval between two lateral line light spots in real time by adjusting the angle of a parallel flat plate (9) so that the interval is equal to the tooth thickness of the tooth to be processed at different tooth height positions;
(4) Setting a working distance regulating and controlling scheme, namely adjusting the working distance of the double-beam laser heat treatment processing head in real time through a mechanical arm to compensate the defocusing amount so as to ensure that double beams are always focused on a processing tooth surface in the laser scanning process;
(5) Synchronous laser quenching scanning is carried out on two tooth surfaces of the tooth to be processed by utilizing two linear light spots output by the double-beam laser heat treatment processing head, double-beam distance regulation and control and working distance regulation are carried out while laser quenching scanning is carried out, and temperature closed-loop control and variable-speed scanning are carried out so as to ensure that the surface quenching temperature of a double-beam irradiation area is controlled in an austenite phase change area; the scanning direction is perpendicular to the length direction of the light spot, and the scanning path is perpendicular to the tooth width direction of the gear;
(6) After the double-beam laser quenching of one tooth is completed, the gear is rotated, two linear light spots output by the double-beam laser heat treatment processing head are focused on two sides of the tooth top of the next tooth, the steps (3) - (5) are repeated, and the double-beam laser quenching treatment is carried out on the next tooth until the laser quenching of all teeth is completed.
2. The vertical incidence dual beam variable speed laser thermal treatment method according to claim 1, wherein the spot length in step (1) is 0.3-1.5mm longer than the tooth width.
3. The vertical incidence type double-beam variable speed laser heat treatment method according to claim 1, wherein in the step (2), the incidence angle of the two laser beams is always kept unchanged, and the included angle between the laser beams and the tooth surface is 25-40 degrees.
4. The vertical incidence type dual beam variable speed laser heat treatment method according to claim 1, wherein the temperature closed loop control process in the step (5) is as follows: and monitoring real-time temperature data of at least two positions of the tooth surfaces at two sides in the linear light spot irradiation area by using a pyrometer, regulating and controlling laser power in real time according to the temperature measured by the tooth surfaces at two sides, wherein the temperature of the light spot irradiation area is in an austenite phase transformation area, and reducing the surface temperature by reducing the laser power when the surface temperature exceeds the upper limit of a preset temperature threshold.
5. The vertical incidence type double-beam variable speed laser heat treatment method according to claim 1, wherein in the step (5), if a scanning area with the tooth thickness of more than or equal to 25mm exists, variable speed scanning treatment is carried out on the scanning area, namely, the scanning speed is reduced to 75-95% of the initial speed.
6. The vertical incidence type double-beam variable speed laser heat treatment method according to claim 1, wherein in the step (5), the temperature of a light spot irradiation area is 50-150 ℃ above Ac3 for the gear material of the medium-low carbon alloy steel, and the temperature of the light spot irradiation area is 40-200 ℃ above Ac1 for the gear material of the spheroidal graphite cast iron.
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| CN202311785927.6A CN117737350A (en) | 2023-12-22 | 2023-12-22 | Vertical incidence type double-beam variable-speed laser heat treatment method |
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