阅读说明：本技术 一种多光束激光淬火方法与装置 (Multi-beam laser quenching method and device ) 是由 胡乾午 吴细水 曾晓雁 徐其瑞 王邓志 于 2021-07-09 设计创作，主要内容包括：本发明公开了一种多光束激光淬火方法以及装置,属于激光淬火领域,采用接续递进加热选区激光淬火方式将多个激光束辐照到工件表面,通过多光束的局部摆动,使每个激光束在不同加热位置上对不同淬火单元进行接续式递进加热,在激光淬火过程中,淬火单元按照线性排列的方式连续运动,淬火单元被递进式持续加热,由于热量累积而使温度逐渐升高,并在最后的激光加热位置达到规定的奥氏体相变温度和淬火深度,通过控制激光淬火工艺参数完成激光淬火。本发明还提供了多光束激光淬火装置。本发明方法可以大幅度提高激光淬火的生产效率,本发明的装置结构巧妙,使用灵活,能实现高效率激光淬火。(The invention discloses a multi-beam laser quenching method and a device, belonging to the field of laser quenching, wherein a plurality of laser beams are irradiated on the surface of a workpiece in a continuous progressive heating selective laser quenching mode, each laser beam is enabled to continuously and progressively heat different quenching units at different heating positions through local swing of the multi-beam, in the laser quenching process, the quenching units continuously move in a linear arrangement mode, the quenching units are continuously heated in a progressive mode, the temperature is gradually increased due to heat accumulation, the final laser heating position reaches the specified austenite phase transition temperature and the quenching depth, and laser quenching is completed by controlling laser quenching process parameters. The invention also provides a multi-beam laser quenching device. The method can greatly improve the production efficiency of laser quenching, and the device has smart structure and flexible use and can realize high-efficiency laser quenching.)

1. A multi-beam laser quenching method is characterized in that a plurality of laser beams are irradiated to the surface of a workpiece in a continuous progressive heating selective laser quenching mode, each laser beam is enabled to continuously and progressively heat different quenching units at different heating positions through local swing of the multi-beam, the quenching units continuously move in a linear arrangement mode in the laser quenching process, the quenching units are continuously heated in a progressive mode, the temperature is gradually increased due to heat accumulation, and the final laser heating position reaches the specified austenite phase transition temperature and the quenching depth to realize quenching,

the quenching unit is an area which is irradiated to the surface of the workpiece by the laser beam after passing through the laser processing head and continuously acts on the surface of the workpiece once.

2. The multi-beam laser quenching method according to claim 1, wherein the laser quenching is performed by controlling laser quenching process parameters including the number of laser beams, laser power, scanning speed, spot size, spacing distance, irradiation period, and irradiation times, wherein,

the spacing distance refers to the distance between two adjacent quenching units;

the irradiation period refers to the sum of one-time continuous irradiation heating time and one-time interval time when the set laser beam swings between two adjacent heating positions;

the irradiation times refer to the times of repeated irradiation required for one quenching unit to reach the required depth of a hardened layer;

the scanning speed refers to a moving speed of the laser beam obtained on the surface of the workpiece due to the deflecting motion.

3. The multiple-beam laser quenching method of claim 2, comprising the steps of:

(1) defining parameter meanings and initial conditions, specifically, setting the total number of quenching units on a workpiece as M, the serial number of the quenching unit currently processed on the workpiece as g, the number of laser beams as K, the serial number of the laser beam currently irradiating the workpiece as eta, the moving distance of the laser beam as delta, the quenching period as T, the irradiation frequency required by one quenching unit as K, the ordinal number of the actual irradiation frequency as i, the quenching speed as V, the movement speed of the laser processing head relative to the workpiece for forming and controlling a plurality of laser beams, the movement direction of the laser processing head relative to the workpiece as X direction, and the initial irradiation position of the laser beam with the serial number as eta on the X axis as X₀+ (eta-1) delta, with X being the extreme irradiation position on the X axis₀+ η · δ, wherein the initial irradiation position of the first laser beam on the X axis is X₀(ii) a The moving distance delta of the laser beam is equal to the spacing distance between two adjacent quenching units in value, and the linear spacing distance of each quenching unit on the X axis is equal; the heating time of one continuous irradiation when the laser beam moves from the initial irradiation position to the limit irradiation position is t₁The one-time gap time when the laser beam rapidly returns from the extreme irradiation position to the initial irradiation position is t₂，t₂Much less than t₁Irradiation period T_bRefers to the heating time t of one continuous irradiation of laser beam₁And a time of clearance t₂Summing; the quenching period T is the irradiation period T_bThe product of the irradiation times K;

then T_b＝t₁+t₂，T＝K*T_b，V＝δ/T_b；

Setting g to be 0, eta to be 1, i to eta, and setting the energy distribution in each quenching unit to be uniform in the whole laser quenching process;

(2) the eta laser beams output after passing through the laser processing head are at respective initial irradiation positions, an initial quenching mode is executed, and the time point is recorded as t₀The eta laser beams start to correspondingly irradiate the eta quenching units and move along with the quenching units, at the moment, the laser beams with the sequence number larger than eta are closed, the current time is set as T, and the irradiation period T is set as_bWhen t-t is₀＝T_bThe moving distance of the laser beam is delta,after the completion, closing the laser beam, and entering into the step (3);

the initial quenching mode is a progressive heating quenching mode in the process of increasing the irradiation light beams from 1 to K, the initial quenching mode is finished after eta is K, and the quenching process of the first quenching unit is finished;

(3) judging whether i is equal to the set irradiation frequency K, if so, finishing quenching in the 1 st quenching unit, enabling g to be g +1 when the designed depth of the hardened layer is reached, and then turning to the step (4); if not, making eta equal to eta +1, and then proceeding to the step (2);

(4) k laser beams output after passing through the laser processing head are positioned at respective initial irradiation positions, a normal quenching mode is executed, and the time point is recorded as t₀(ii) a Setting the current time as t, and enabling the K laser beams to correspondingly irradiate the K quenching units and move along with the movement of the quenching units; when t-t₀＝T_bWhen the laser beam moves by a distance delta, the laser beam is closed after the laser beam is completed, and g is equal to g +1, W₂Finishing quenching in the g quenching unit until the depth of the designed hardened layer is reached, and then turning to the step (5);

(5) judging whether g is equal to W₂If yes, finishing quenching in the M-K quenching units, enabling i to be 1 and eta to be K-i to reach the designed depth of a hardening layer, and entering the step (6); otherwise, turning to the step (4);

(6) the eta laser beams output after passing through the laser processing head are at respective initial irradiation positions, a tail quenching mode is executed, and the time point is recorded as t₀(ii) a Setting the current time as t, and enabling the eta laser beams to start to correspondingly irradiate the eta quenching units and move along with the quenching units; at this time, the laser beam with the serial number less than i is closed; when t-t₀＝T_bWhen P is equal to M-K + i, the quenching of the P-th quenching unit is finished, and the designed depth of a hardened layer is reached;

the tail quenching mode is a specific progressive heating quenching mode in the process of reducing the irradiation light beams from K to 1, and is finished after eta is 1, and the quenching process of the Mth quenching unit is finished;

(7) judging whether g is equal to M or not, if so, indicating that all quenching units generate laser phase change hardening to form a laser quenching hardening area and reach the designed hardening layer depth, and then turning to the step (8); if not, making i equal to i +1 and g equal to g +1, and then proceeding to step (6);

(8) and (6) ending.

4. The multi-beam laser quenching method according to claim 3, wherein the plurality of laser beams constitute a laser beam group, and the center point of the preceding laser beam limit irradiation position of two adjacent laser beams in one laser beam group is identical to the center point of the subsequent laser beam initial irradiation position.

5. The multi-beam laser quenching method according to claim 4, wherein in the normal quenching mode, the number of quenching units heated at one time is the same as the number of laser beams included in one laser beam group.

6. A multi-laser quenching device is characterized by comprising a laser group, a control unit, a light guide unit, a mechanical motion unit and a laser processing head array, wherein,

the laser unit is used for emitting laser beams for laser quenching, the light guide unit is connected with the laser unit and the laser processing head array, the laser processing head array comprises a plurality of laser processing heads distributed in an array mode, the light guide unit is used for guiding the laser beams emitted by the laser to the laser processing heads, the laser processing heads are used for enabling the received laser to be incident to the appointed positions of the workpieces according to the set angles, the mechanical movement unit is used for enabling the workpieces to move relative to the quenching laser and achieving scanning movement of the quenching laser relative to the workpieces, the laser processing heads are connected with the mechanical movement unit so that the quenching laser can be adjusted under the driving of the mechanical movement unit, and the control unit is respectively electrically connected with the laser unit, the mechanical movement unit and the laser processing head array and can be used for adjusting laser parameters and controlling the laser quenching process.

7. A multiple laser quenching apparatus as claimed in claim 6 wherein the mechanical movement unit is a flatbed or articulated robot for carrying the entire workpiece or the entire laser processing head array to enable movement of the workpiece relative to the quenching laser,

the laser processing heads have the same structure and comprise a deflection mirror, a deflection mirror bracket and a rotating shaft, the deflection mirror is arranged on the deflection mirror bracket and is used for adjusting the emergent angle of the incident laser beam, the deflection mirror bracket is connected with the rotating shaft,

the mechanical motion unit further comprises a deflection mirror motor, the deflection mirror motor is arranged on the main body structure of the laser processing head and connected with the rotating shaft so as to drive the rotating shaft to drive the deflection angle of the deflection mirror, and then the quenching laser moves the quenching unit.

8. The multi-laser hardening apparatus of claim 7, wherein the plurality of output beams of the plurality of laser processing heads in the laser processing head array are symmetrically and obliquely distributed along the central axis, and the deflection angle of the deflection mirror of each laser processing head is γ 1, γ 2, γ · · · · · γ n, in order from large to small in the ZOX coordinate system, so that the plurality of output beams irradiate a plurality of hardening units on the surface of the workpiece, each of the hardening units having a phase separation of δ, γ n being smaller than 20 °, n being the number of laser processing heads.

9. The multi-laser hardening apparatus of claim 8, wherein the laser processing head includes a focusing mirror, a reflecting mirror, and a protective mirror, wherein the laser beam incident to the laser processing head passes through the focusing mirror, the reflecting mirror, the deflecting mirror, and the protective mirror in sequence and then exits onto the workpiece, an angle between a reflecting surface of the reflecting mirror and a right side surface perpendicular to the optical head base in the ZOY coordinate system is α, an angle between a reflecting surface of the deflecting mirror and a right side surface perpendicular to the optical head base in the ZOY coordinate system is β, an α angle and a β angle are equal when an input beam and an output beam of the laser processing head are parallel, and an α angle or a β angle in the ZOY coordinate system is in a range of 20 ° to 30 °.

10. The multi-laser quenching apparatus as claimed in claim 9, wherein the laser is a fiber laser, a semiconductor laser, a disc laser or a YAG laser,

the light guide unit is an optical fiber transmission system or a hard optical path system consisting of an optical lens group, and transmits laser beams of the laser group to light inlets of the plurality of laser processing heads.

Technical Field

The invention belongs to a laser surface strengthening treatment technology, and relates to a multi-beam laser quenching method and a multi-beam laser quenching device.

Background

The selective laser quenching can form a composite structure of 'soft matrix + hardening zone' on the surface of the workpiece, so that the workpiece has good matching of high wear resistance and high toughness. The precondition of laser quenching of the workpiece is to ensure that the quenching unit finishes the quenching process according to the given time under the given laser power.

After the patterns and the sizes of the quenching units are determined, the improvement of the production efficiency and the quenching accuracy of the quenching units with extremely large number of patterns or smaller sizes is a new problem to be considered.

After the pattern and the size of the quenching unit are determined, in order to improve the production efficiency, a plurality of laser beams are required to be adopted for the selective laser quenching operation. When multiple beams are adopted for selective laser quenching operation of a quenching unit with a small size, due to the fact that the size of an optical head is large, innovative design needs to be carried out on the aspects of laser processing optical structure, arrangement mode and quenching principle so as to meet the requirement of high-efficiency online production.

Therefore, it is necessary to develop a novel multi-beam laser quenching method and apparatus to improve the quenching efficiency and the quenching accuracy.

Disclosure of Invention

In order to solve the problem of low production efficiency of the existing selective laser quenching technology, the invention provides a continuous progressive heating selective laser quenching method, which can greatly improve the production efficiency of laser quenching; the invention also provides a device for realizing the method, which has the advantages of ingenious structure, flexible use and capability of realizing high-efficiency laser quenching.

In order to achieve the above object, the present invention provides a multi-beam laser quenching method, wherein a plurality of laser beams are irradiated to the surface of a workpiece by a continuous progressive heating selective laser quenching method, each laser beam performs continuous progressive heating on different quenching units at different heating positions by local oscillation of the multi-beam, the quenching units continuously move in a linear arrangement manner during laser quenching, the quenching units are continuously heated in a progressive manner, the temperature is gradually increased due to heat accumulation, and the final laser heating position reaches a specified austenite phase transition temperature and quenching depth to achieve quenching, wherein the quenching units refer to regions where the laser beams are irradiated to the surface of the workpiece after passing through a laser processing head and continuously act on the surface of the workpiece at one time.

Further, laser quenching is completed by controlling laser quenching process parameters, wherein the laser quenching process parameters comprise laser beam quantity, laser power, scanning speed, spot size, spacing distance, irradiation period and irradiation frequency, wherein,

the spacing distance refers to the distance between two adjacent quenching units;

the irradiation period refers to the sum of one-time continuous irradiation heating time and one-time interval time when the set laser beam swings between two adjacent heating positions;

the irradiation times refer to the times of repeated irradiation required for one quenching unit to reach the required depth of a hardened layer;

the scanning speed refers to a moving speed of the laser beam obtained on the surface of the workpiece due to the deflecting motion.

Further, the method comprises the following steps:

(1) defining parameter meanings and initial conditions, specifically, setting the total number of quenching units on a workpiece as M, the serial number of the quenching unit currently processed on the workpiece as g, the number of laser beams as K, the serial number of the laser beam currently irradiating the workpiece as eta, the moving distance of the laser beam as delta, the quenching period as T, the irradiation frequency required by one quenching unit as K, the ordinal number of the actual irradiation frequency as i, the quenching speed as V refers to the movement speed of a laser processing head forming and controlling a plurality of beams of laser relative to the workpiece, the movement direction of the laser processing head relative to the workpiece as X direction, and the serial number as eta of the laser beam on the workpiece as KThe initial irradiation position on the X axis is X₀+ (eta-1) delta, with X being the extreme irradiation position on the X axis₀+ η · δ, wherein the initial irradiation position of the first laser beam on the X axis is X₀(ii) a The moving distance delta of the laser beam is equal to the spacing distance between two adjacent quenching units in value, and the linear spacing distance of each quenching unit on the X axis is equal; the heating time of one continuous irradiation when the laser beam moves from the initial irradiation position to the limit irradiation position is t₁The one-time gap time when the laser beam rapidly returns from the extreme irradiation position to the initial irradiation position is t₂，t₂Much less than t₁Irradiation period T_bRefers to the heating time t of one continuous irradiation of laser beam₁And a time of clearance t₂Summing; the quenching period T is the irradiation period T_bThe product of the irradiation times K;

then T_b＝t₁+t₂，T＝K*T_b，V＝δ/T_b；

Setting g to be 0, eta to be 1, i to eta, and setting the energy distribution in each quenching unit to be uniform in the whole laser quenching process;

(2) the eta laser beams output after passing through the laser processing head are at respective initial irradiation positions, an initial quenching mode is executed, and the time point is recorded as t₀The eta laser beams start to correspondingly irradiate the eta quenching units and move along with the quenching units, at the moment, the laser beams with the sequence number larger than eta are closed, the current time is set as T, and the irradiation period T is set as_bWhen t-t is₀＝T _bWhen the laser beam moves by the distance delta, closing the laser beam after the laser beam moves, and entering the step (3);

the initial quenching mode is a progressive heating quenching mode in the process of increasing the irradiation light beams from 1 to K, the initial quenching mode is finished after eta is K, and the quenching process of the first quenching unit is finished;

(3) judging whether i is equal to the set irradiation frequency K, if so, finishing quenching in the 1 st quenching unit, enabling g to be g +1 when the designed depth of the hardened layer is reached, and then turning to the step (4); if not, making eta equal to eta +1, and then proceeding to the step (2);

(4) k laser beams output after passing through the laser processing head are positioned at respective initial irradiation positions, a normal quenching mode is executed, and the time point is recorded as t₀(ii) a Setting the current time as t, and enabling the K laser beams to correspondingly irradiate the K quenching units and move along with the movement of the quenching units; when t-t₀＝T_bWhen the laser beam moves by a distance delta, the laser beam is closed after the laser beam is completed, and g is equal to g +1, W₂Finishing quenching in the g quenching unit until the depth of the designed hardened layer is reached, and then turning to the step (5);

(5) judging whether g is equal to W₂If yes, finishing quenching in the M-K quenching units, enabling i to be 1 and eta to be K-i to reach the designed depth of a hardening layer, and entering the step (6); otherwise, turning to the step (4);

(6) the eta laser beams output after passing through the laser processing head are at respective initial irradiation positions, a tail quenching mode is executed, and the time point is recorded as t₀(ii) a Setting the current time as t, and enabling the eta laser beams to start to correspondingly irradiate the eta quenching units and move along with the quenching units; at this time, the laser beam with the serial number less than i is closed; when t-t₀＝T_bWhen P is equal to M-K + i, the quenching of the P-th quenching unit is finished, and the designed depth of a hardened layer is reached;

the tail quenching mode is a specific progressive heating quenching mode in the process of reducing the irradiation light beams from K to 1, and is finished after eta is 1, and the quenching process of the Mth quenching unit is finished;

(7) judging whether g is equal to M or not, if so, indicating that all quenching units generate laser phase change hardening to form a laser quenching hardening area and reach the designed hardening layer depth, and then turning to the step (8); if not, making i equal to i +1 and g equal to g +1, and then proceeding to step (6);

(8) and (6) ending.

Further, a plurality of laser beams form a laser beam group, and the central point of the previous laser beam limit irradiation position of two adjacent laser beams in the laser beam group is the same as the central point of the next laser beam initial irradiation position.

Further, in the normal quenching mode, the number of quenching units heated at one time is the same as the number of laser beams included in one laser beam group.

According to still another aspect of the present invention, there is also provided a multi-laser hardening apparatus including a laser group, a control unit, a light guide unit, a mechanical movement unit, and a laser processing head array, wherein,

the laser unit is used for emitting laser beams for laser quenching, the light guide unit is connected with the laser unit and the laser processing head array, the laser processing head array comprises a plurality of laser processing heads distributed in an array mode, the light guide unit is used for guiding the laser beams emitted by the laser to the laser processing heads, the laser processing heads are used for enabling the received laser to be incident to the appointed positions of the workpieces according to the set angles, the mechanical movement unit is used for enabling the workpieces to move relative to the quenching laser and achieving scanning movement of the quenching laser relative to the workpieces, the laser processing heads are connected with the mechanical movement unit so that the quenching laser can be adjusted under the driving of the mechanical movement unit, and the control unit is respectively electrically connected with the laser unit, the mechanical movement unit and the laser processing head array and can be used for adjusting laser parameters and controlling the laser quenching process.

Furthermore, the mechanical motion unit is a flat car or a multi-joint robot and is used for bearing a whole workpiece or a whole laser processing head array so as to realize the movement of the workpiece relative to quenching laser, the structures of the laser processing heads are the same, each laser processing head comprises a deflection mirror, a deflection mirror support and a rotating shaft, the deflection mirror is arranged on the deflection mirror support and used for adjusting the outgoing angle of a laser beam incident to the deflection mirror support, the deflection mirror supports are connected with the rotating shafts, the mechanical motion unit further comprises a deflection mirror motor, the deflection mirror motor is arranged on the main body structure of the laser processing head and connected with the rotating shafts so as to drive the rotating shafts to drive the deflection mirror to deflect the angle, and further the movement of the quenching laser to the quenching unit is realized.

Furthermore, in the laser processing head array, a plurality of output light beams of a plurality of laser processing heads are symmetrically and obliquely distributed according to a central axis, the deflection angles of the deflection mirrors of the laser processing heads in a ZOX coordinate system are gamma 1, gamma 2, gamma-n from large to small, so that the output light beams irradiate a plurality of quenching units on the surface of a workpiece, the quenching units are spaced at intervals, the angle of gamma n is smaller than 20 degrees, and n is the number of the laser processing heads.

Further, the laser processing head comprises a focusing mirror, a reflecting mirror and a protective mirror, wherein a laser beam incident to the laser processing head sequentially passes through the focusing mirror, the reflecting mirror, a deflecting mirror and the protective mirror and then is emitted to a workpiece, the deflecting mirror and the reflecting mirror are parallel, an included angle between a reflecting surface of the reflecting mirror and the vertical right side surface of the optical head seat in the ZOY coordinate system is alpha, an included angle between the reflecting surface of the deflecting mirror and the vertical right side surface of the optical head seat in the ZOY coordinate system is beta, when an input light beam and an output light beam of the laser processing head are parallel, an alpha angle and a beta angle are equal, and in the ZOY coordinate system, the alpha angle or the beta angle ranges from 20 degrees to 30 degrees.

Furthermore, the laser is a fiber laser, a semiconductor laser, a disc laser or a YAG laser, the light guide unit is a fiber transmission system or a hard optical path system composed of an optical lens group, and the light guide unit transmits the laser beam of the laser group to the light inlet of the plurality of laser processing heads.

The invention adopts a continuous progressive heating selective laser quenching method, changes the single-beam laser quenching mode in the existing laser quenching process into a multi-beam laser quenching mode, and is characterized in that: on one hand, the production efficiency can be improved by heating a plurality of laser quenching units simultaneously; on the other hand, the mechanical device can easily realize the uniform motion relative to the workpiece through the local tracking movement of the laser beam, the production mode of the laser quenching is similar to the motion mode of printing, and the motion process of the mechanical structure of the conventional selective laser quenching production is very complicated when the printing motion mode is realized.

Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

(1) the invention adopts a plurality of laser beams to carry out laser quenching on a plurality of quenching units, and can simultaneously quench the plurality of units in the same time period, the laser heating mode is continuous progressive heating, and the more the number of the adopted laser beams is, the higher the quenching production efficiency is. The method can adopt a one-line multi-laser-beam quenching mode and a multi-laser-beam quenching mode with more than two lines, has very flexible laser quenching mode and strong designability, is adjusted according to actual engineering requirements, and has very practical engineering value.

(2) The method comprises the steps of converting the existing single laser beam heating and quenching process into a multi-laser beam continuous progressive heating and laser quenching process, enabling the maximum temperature of the surface of a workpiece caused by the total energy of continuously heated laser after the last laser beam is heated to reach the austenite phase transition temperature of a metal material by selecting appropriate process parameters including laser power, laser beam quantity, scanning speed, quenching speed, spot size, spacing distance, irradiation period, irradiation frequency and the like, and then realizing quenching and hardening. The method can also select all arranged laser beams to carry out continuous progressive heating quenching according to the requirement, and can also select a plurality of laser beams to carry out continuous progressive heating quenching. Therefore, the process parameter range and the process method which can be selected are more, and the requirements of different working conditions can be met.

(3) According to the continuous progressive heating laser quenching process provided by the invention, the size and the spacing distance of the light spot can be adjusted in a wider range according to the actual requirements of workpieces so as to adapt to the requirements of different working conditions.

(4) The quenching method adopts the local tracking movement of multiple laser beams to carry out quenching, so that the mechanical device can easily realize uniform motion relative to the workpiece, the motion lag caused by frequent start and stop of the mechanical device during motion in the selective laser quenching is avoided, and the production efficiency of the laser quenching is effectively improved.

(5) The method can obviously improve the depth of laser quenching under the condition of the same laser power; or a larger number of laser beams and higher laser power are adopted, and the laser quenching efficiency is greatly improved within the same quenching time and under the condition of the same hardened layer depth. Therefore, the invention can break through the limitations of small quantity of laser beams, low laser power and quenching speed under the condition of the existing laser quenching process (single-beam laser quenching process), and solves the technical problems of limited depth of the hardening layer, low production efficiency and the like of the existing laser quenching.

(6) The deflection mirror in the device can realize local rapid tracking heating of the light beam, so that the method can realize rapid selective laser quenching of multiple laser beams, and can further improve the production efficiency of laser quenching by adopting high-power laser beams.

Drawings

Fig. 1 is a schematic structural view of a laser processing head according to an embodiment of the present invention.

Fig. 2 is a schematic structural view of a deflection mirror of a laser processing head according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a multi-laser processing head array according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of the principle of multi-beam laser quenching according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of a multi-column multi-laser-beam quenching apparatus according to an embodiment of the invention.

FIG. 6 is a schematic diagram of a multi-beam laser quenching apparatus according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

In the device, the high-speed scanning function of the deflection mirror is combined, so that the local rapid tracking heating of the light beam can be realized, and the production efficiency of laser quenching can be improved by adopting a high-power laser beam.

In order to more clearly illustrate the embodiments of the present invention, the terms related to the present invention are defined herein as follows:

a quenching unit: refers to a region where a laser beam passes through a laser processing head, is irradiated to the surface of a workpiece, and is successively applied to the surface of the workpiece at one time. The size of the quenching unit is basically equal to the size of a laser spot on the surface of the workpiece. The laser energy distribution within a quench unit should be substantially uniform.

Irradiation period: the method is characterized in that a laser beam carries out one-time continuous irradiation heating time (t) on the surface of a workpiece within the laser spot size range in a quenching unit₁) And a time of clearance (t)₂) Sum, is denoted as T_b. At t₁Within the time, the laser beam moves from the initial irradiation position to the extreme irradiation position and continuously irradiates one quenching unit at a time; at t₂Rapidly returning the laser beam from the extreme irradiation position to the initial irradiation position within time; in general t₂Much less than t₁And the central point of the limit irradiation position of the previous laser beam is the same as the central point of the initial irradiation position of the next laser beam.

Irradiation times: the number of times of repeated irradiation is recorded as K for one quenching unit to reach the required depth of the hardened layer.

And (3) quenching period: refers to the number of times of irradiation (T) to one quenching unit_b) The product with the irradiation period (K) is denoted as T.

Scanning speed: refers to the speed of movement of the laser beam obtained at the surface of the workpiece as a result of the rotation of the deflection mirror.

Quenching speed: refers to the movement speed of the laser processing head relative to the workpiece and is marked as V. The direction of movement of the laser processing head relative to the workpiece is defined as the X direction.

In the invention, the laser energy distribution in one quenching unit is basically uniform, multiple-beam quenching forms a laser quenching layer by means of accumulated heat effect generated by interval continuous laser heating and a heat conduction mode and reaches the required depth, the number of the quenching units processed at each time in the normal quenching stage is the same as that of laser beams, the temperature of the quenching units is gradually increased from the first irradiation beam to the temperature of austenite phase transition after the last irradiation beam is finished, and the quenching hardening is realized.

The multi-beam continuous progressive heating laser quenching method can be realized by adopting the following specific processes:

(1) setting the total number of quenching units on a workpiece as M, the serial number of the quenching unit currently processed on the workpiece as g, the number of laser beams as K, the serial number of the laser beams currently irradiating the workpiece as eta, the moving distance of the laser beams as delta, the quenching period as T, the number of times of irradiation required by one quenching unit as K, the ordinal number of the actual irradiation times as i, and the quenching speed as V;

the quenching speed V is the movement speed of the laser processing head relative to the workpiece; the movement direction of the laser processing head relative to the workpiece is the X direction;

the initial irradiation position of the laser beam with the sequence number eta on the X axis is X₀+ (eta-1) delta, with X being the extreme irradiation position on the X axis₀+ η · δ, wherein the initial irradiation position of the first laser beam on the X axis is X₀(ii) a The moving distance delta of the laser beam is equal to the spacing distance between two adjacent quenching units in value, and the linear spacing distance of each quenching unit on the X axis is equal;

the heating time of one continuous irradiation when the laser beam moves from the initial irradiation position to the limit irradiation position is t₁(ii) a The one-time gap time when the laser beam rapidly returns from the extreme irradiation position to the initial irradiation position is t₂In general, t₂Much less than t₁(ii) a Wherein, the central point of the limit irradiation position of the previous laser beam is the same as the central point of the initial irradiation position of the next laser beam;

irradiation period T_bRefers to the heating time t of one continuous irradiation of laser beam₁And a time of clearance t₂Summing;

the quenching period T is the irradiation period T_bThe product of the irradiation times K;

then T_b＝t₁+t₂，T＝K*T_b，V＝δ/T_b；

Let g equal to 0, η equal to 1, i equal to η; and the energy distribution in each quenching unit is basically uniform and consistent in the whole laser quenching process;

(2) the eta laser beams output after passing through the laser processing head are at respective initial irradiation positions, an initial quenching mode is executed, and the time point is recorded as t₀(ii) a The eta laser beams start to correspondingly irradiate the eta quenching units and move along with the quenching units; at the moment, the laser beam with the sequence number larger than eta is closed; let the current time be T, the irradiation period T_bWhen t-t is₀＝T _bWhen the laser beam moves by the distance delta, closing the laser beam after the laser beam moves, and entering the step (3);

the initial quenching mode is the initial stage of a progressive heating quenching mode that irradiation light beams are increased from 1 to K, the initial quenching mode is ended after eta is K, and the quenching process of the first quenching unit is completed;

(3) judging whether i is equal to the set irradiation frequency K, if so, finishing quenching in the 1 st quenching unit, enabling g to be g +1 when the designed depth of the hardened layer is reached, and then turning to the step (4); if not, making eta equal to eta +1, and then proceeding to the step (2);

(4) k laser beams output after passing through the laser processing head are positioned at respective initial irradiation positions, a normal quenching mode is executed, and the time point is recorded as t₀(ii) a Setting the current time as t, and enabling the K laser beams to correspondingly irradiate the K quenching units and move along with the movement of the quenching units; when t-t₀＝T_bWhen the laser beam moves by a distance delta, the laser beam is closed after the laser beam is completed, and g is equal to g +1, W₂Finishing quenching in the g quenching unit until the depth of the designed hardened layer is reached, and then turning to the step (5);

(5) judging whether g is equal to W₂If yes, the quenching of the (M-K) th quenching unit is finished, the designed depth of a hardening layer is reached, i is 1, eta is K-i, and the process goes to the step (6); otherwise, turning to the step (4);

(6) the eta laser beams output after passing through the laser processing head are at respective initial irradiation positions, a tail quenching mode is executed, and the time point is recorded as t₀(ii) a Setting the current time as t, eta laser beams start to correspondingly irradiate eta quenching units andmove with the quenching unit; at this time, the laser beam with the serial number less than i is closed; when t-t₀＝T_bWhen P is equal to M-K + i, the quenching of the P-th quenching unit is finished, and the designed depth of a hardened layer is reached;

the tail quenching mode is a ending stage of a progressive heating quenching mode that irradiation light beams are reduced from K to 1, and is ended after eta is 1, and the quenching process of the Mth quenching unit is completed;

(7) judging whether g is equal to M or not, if so, indicating that all quenching units generate laser phase change hardening to form a laser quenching hardening area and reach the designed hardening layer depth, and then turning to the step (8); if not, making i equal to i +1 and g equal to g +1, and then proceeding to step (6);

(8) end up

In the step (1), the laser beam incident to the laser processing head is called as the input beam, the energy distribution mode of the input beam can be a Gaussian mode or a flat-top mode, and the laser beam in the flat-top mode is favorable for ensuring the uniformity of the depth and the hardness of the quench-hardened layer and improving the quality of laser quenching. The laser beam irradiated to the surface of the workpiece after passing through the laser processing head is called as an output beam, and the number of quenching units heated at one time in the normal quenching state is the same as that of the output beam.

Step (2), irradiating the laser beam according to set process parameters, wherein the process parameters comprise: laser power, laser beam serial number, scanning speed, spot size, spacing distance, and laser action time t in quenching unit₁And a pause time t₂And the like.

The laser processing head structure of the invention is shown in fig. 1, and comprises a focusing mirror 23, a reflecting mirror 24, a deflecting mirror motor 25, a deflecting mirror support 26, a deflecting mirror 27, a rotating shaft 273 and a protective mirror 29; wherein, the included angle between the reflection surface of the reflector 24 and the right side surface 28 perpendicular to the headstock in the ZOY coordinate system is α, and the included angle between the reflection surface of the deflection mirror 27 and the right side surface 28 perpendicular to the headstock in the ZOY coordinate system is β; when the input beam 3 'and the output beam 3 are required to be parallel, the angle alpha is equal to the angle beta, in order to reduce the distance between the input beam 3' and the output beam 3, the angle alpha (or the angle beta) is required to be less than 45 degrees, and in the ZOY coordinate system, the preferred angle range of the angle alpha (or the angle beta) is 20 degrees to 30 degrees; where the input beam 3' is required to be non-parallel to the output beam 3, the α and β angles may not be equal; the deflection mirror 27 is constructed as shown in FIG. 2, and includes a deflection mirror 271, a mirror plate 272, and a rotating shaft 273; the input light beam 3' passes through the focusing mirror 23 and the deflecting mirror 27 and then is irradiated on the quenching unit 4 of the workpiece 5; wherein, the deflection mirror motor 25 drives the deflection mirror 27 to rotate around the rotation axis 273 in ZOX coordinate system, and the rotation angle is γ (as shown in fig. 3); under the driving of the quick deflection of the deflection mirror, the laser beam is driven to track, move and heat, and the moving distance is the spacing distance delta between two adjacent quenching units.

The structure of the multi-laser processing head array of the invention is shown in figure 3, 10 laser processing heads are a first laser processing head 2-1, a second laser processing head 2-2, a third laser processing head 2-3, a fourth laser processing head 2-4, a fifth laser processing head 2-5, a sixth laser processing head 2-6, a seventh laser processing head 2-7, an eighth laser processing head 2-8, a ninth laser processing head 2-9, a tenth laser processing head 2-10, 10 laser processing heads correspondingly output 10 output light beams, 10 output light beams are a first output light beam 3-1, a second output light beam 3-2, a third output light beam 3-3, a fourth output light beam 3-4, a fifth output light beam 3-5 and a sixth output light beam 3-6, The seventh output beam 3-7, the eighth output beam 3-8, the ninth output beam 3-9, the tenth output beam 3-10, 10 output beams are symmetrically distributed obliquely according to the center point P, and the deflection angles of the deflection mirror of each laser processing head in an ZOX coordinate system are respectively a first deflection angle γ 1, a second deflection angle γ 2, a third deflection angle γ 3, a fourth deflection angle γ 4, a fifth deflection angle γ 5, a sixth deflection angle γ 6, a seventh deflection angle γ 7, an eighth deflection angle γ 8, a ninth deflection angle γ 9, and a tenth deflection angle γ 10. 10 quenching units for irradiating the 10 output beams to the surface of the workpiece, wherein the interval distance between every two quenching units is delta; the preferred angle of γ 10 is less than 20 °, at which point the increase in spot size in the X direction is less than 6%, with no significant effect on the quality of the laser quench.

The multiple-beam laser quenching process of the invention is shown in FIG. 4, and normal quenching is performedIn the fire stage, 10 output light beams irradiate 10 quenching units, wherein the 10 quenching units are respectively a first quenching unit 4-1a, a second quenching unit 4-2a, a third quenching unit 4-3a, a fourth quenching unit 4-4a, a fifth quenching unit 4-5a, a sixth quenching unit 4-6a, a seventh quenching unit 4-7a, an eighth quenching unit 4-8a, a ninth quenching unit 4-9a, a tenth quenching unit 4-10a and an eleventh quenching unit 4-11 a. The interval distance of the quenching units is delta; the quenching speed is V, and the movement direction of the laser processing head relative to the workpiece is X direction; in one irradiation period T_bHeating time t₁The output light beam moves from the initial irradiation position to the limit irradiation position by a distance delta; in one irradiation period T_bTime of gap t₂In which the output beam is turned off and quickly returned from the extreme irradiation position to the initial irradiation position, and also moved by a distance delta, typically t₂Much less than t₁Wherein, the central point of the limit irradiation position of the previous output light beam is the same as the central point of the initial irradiation position of the next output light beam;

the initial quenching mode in the step (2) is as follows:

(1) the output light beam 3-1 after passing through the laser processing head is at t₁Continuously heating the 4-1a quenching unit once in time, moving the quenching unit from the initial irradiation position to the limit irradiation position, turning off the laser beam after the heating is finished, and stopping the laser beam at t₁Quickly returning to the initial irradiation position within time; the moving speed of the workpiece is V;

(2) the output light beam 3-1 and the output light beam 3-2 after passing through the laser processing head are at t₁Continuously heating the 4-1 a' and 4-2a quenching units once in time, moving the quenching units from the initial irradiation position to the limit irradiation position, turning off the laser beam after the completion of the heating, and stopping the laser beam at t₂Quickly returning to the initial irradiation position within time; the moving speed of the workpiece is V; wherein, the 4-2a quenching unit in the step is the 4-1a quenching unit moved in the first step; the 4-1 a' quenching unit is a newly added quenching unit in the step.

(3) Repeating the steps till the step (10). The (10) step is as follows: ten output beams after passing through the laser processing head at t₁Within ten timesThe quenching units are continuously heated once and moved from the initial irradiation position to the extreme irradiation position, and then the laser beam is turned off and the temperature is t₂Quickly returning to the initial irradiation position within time; the moving speed of the workpiece is V; wherein the 4-11a quenching unit of this step completes the quenching process, which is the 4-1a quenching unit moved in the above-mentioned first step.

The normal quenching mode in the step (4) is as follows:

ten output beams after passing through the laser processing head at t₁Continuously heating ten quenching units once in time, moving the quenching units from an initial irradiation position to an extreme irradiation position, turning off the laser beam after the heating is finished, and stopping heating at t₂Quickly returning to the initial irradiation position within time; the moving speed of the workpiece is V; at this time, the eleventh quenching unit 4-11a completes the quench hardening; in the normal quenching mode, quenching of one quenching unit is completed after each irradiation period, and the quenching speed is more than 10 times of that of single-beam laser quenching.

The tail quenching mode in the step (6) is as follows:

(1) the output beam 3-1 is turned off, and the other nine output beams after passing through the laser processing head are at t₁Continuously heating the quenching units 4-2 a-4-10 a from the second to the tenth quenching units for one time, moving the quenching units from the initial irradiation position to the limit irradiation position, turning off the laser beam after the heating is finished, and stopping the laser beam at t₁Quickly returning to the initial irradiation position within time; the moving speed of the workpiece is V; at this time, the eleventh quenching unit 4-11a completes the quench hardening;

(2) the output light beam 3-1 and the output light beam 3-2 are closed, and other eight output light beams after passing through the laser processing head are at t₁Continuously heating the quenching units 4-3a to 4-10a once within the time, moving the quenching units from the initial irradiation position to the limit irradiation position, closing the laser beams after the heating is finished, and stopping the laser beams at t₁Quickly returning to the initial irradiation position within time; the moving speed of the workpiece is V; at this time, the eleventh quenching unit 4-11a completes the quench hardening;

(3) repeating the steps until the step (10) is reached: the other output beams are turned off and the tenth output beam 3-10 is at t₁Time to tenth quench unit4-10a, performing continuous heating once, moving from the initial irradiation position to the extreme irradiation position, turning off the laser beam after completion, and stopping at t₁Quickly returning to the initial irradiation position within time; the moving speed of the workpiece is V; at this time, the eleventh quenching unit 4-11a completes the quench hardening.

The invention can adopt a single-row multi-laser-beam quenching mode and can also adopt a multi-laser-beam quenching mode with more than two rows. As shown in fig. 5, the multiple-row multiple-laser-beam quenching apparatus of the present invention adjusts the included angle α of the reflecting mirror 24 in a ZOX coordinate system, and simultaneously adjusts the included angle β of the deflecting mirror 27, so that three laser processing heads in a total of three rows of laser processing heads 2a, 2b, and 2c output a first beam group 3a, a second beam group 3b, and a third beam group 3c, the three beam groups deflect at an angle, respectively, corresponding to a first angle θ 1, a second angle θ 2, and a third angle θ 3, and the spacing distances between quenching units formed on the surface of the workpiece are δ; the multiple-row multiple-laser-beam continuous heating selective laser quenching method can further improve the efficiency of laser quenching.

The key point of the method is that the discontinuous quenching process of the selective laser quenching is changed into a quasi-continuous quenching process by a continuous progressive heating method, the laser quenching can be carried out by adopting higher laser power and higher quenching speed, and a hardening layer with larger depth is obtained on the premise of ensuring that the surface of a workpiece is not obviously melted. In practical engineering, suitable process parameters can be selected according to the type of material and application of the workpiece to be quenched, and the type and power of the laser used

The laser adopted by the method can be a fiber laser, a semiconductor laser, a disc laser or a YAG laser.

The mechanical mechanism 6 can be a common flat car, a numerical control flat car, a steel rail laser quenching car, a multi-joint robot (mechanical arm) and other motion mechanisms, and can adopt a single-shaft or multi-shaft linkage mode according to the actual processing requirements.

The light guide system 1 may be an optical fiber transmission system, or may be a hard optical path light guide system composed of an optical lens group. The light guide system 1 transmits the laser beams of the laser group 8 to the light entrance of the laser processing head 2.

Fig. 6 is a schematic diagram of a multi-beam laser quenching apparatus according to an embodiment of the present invention, and it can be seen from the diagram that the apparatus of the present invention is used in the following process:

firstly, a plurality of laser processing heads 2 are arranged in an array and adjusted above a workpiece 5, and laser beams output by a laser group 8 are transmitted to a light inlet of the laser processing heads 2 through a light guide unit 1.

Secondly, on the premise of not outputting laser beams, confirming parameters (including laser power, spot size, irradiation times, t) of laser passing through the laser processing head according to programming design₁、t₂Irradiation period) is consistent with the design.

Confirming laser quenching technological parameters, and starting a laser group 8;

step four, the mechanical mechanism 6 moves at a constant speed V relative to the workpiece 5 under the control of the control unit 7; a plurality of output light beams 3 of a plurality of laser processing heads 2 are irradiated to a plurality of quenching units 4 on the surface of a workpiece to carry out progressive heating selective laser quenching;

step five, repeating the step three to the step four until all the quenching units on the surface of the workpiece are traversed, and obtaining a laser phase change quenching layer on the surface of the workpiece

The invention can carry out laser quenching strengthening on workpieces such as large dies, machine tool guide rails, steel rails and the like, and obviously improves the efficiency and the depth of laser quenching.

Example 1: the application of the selective multi-beam laser quenching process in the laser quenching of the steel rail.

In the embodiment, a fiber laser is adopted to carry out area-selection array type laser quenching on a U71Mn steel rail, ten lasers are output from ten lasers, the power of each laser is 850W, the spot sizes of the ten lasers on a workpiece are phi 7mm, the spacing distance delta between quenching units is 10mm, and the size and the array of the quenching units are the same as the array of laser beam spots input. t is t₁Is 0.1s, t₂0.001s, 10 times of irradiation and 1.0 quenching period1s and the quenching depth is 0.85 mm. Wherein the quenching motion mode is uniform motion, the quenching speed is 5940.6mm/min,

the conventional laser quenching method adopts a single light beam to carry out single continuous laser quenching on a single quenching unit, the laser power is 1100W, the diameter of a light spot is phi 7mm, and the spacing distance delta between the quenching units is 10 mm. The quenching time was 1.0s, and the resulting quenching depth was 0.83 mm. Wherein, the quenching motion mode is a motion mode of continuously starting and stopping, and the actual quenching speed is 360 mm/min.

For the workpiece, the quenching efficiency of the ten light spots of the embodiment is 16.5 times that of the prior art, and the quenching depth is about 1.02 times that of the prior art.

The invention adopts a mode of arranging a plurality of laser processing heads at intervals to carry out selective laser quenching, changes a single-beam laser quenching mode in the existing laser quenching process into a quenching mode of multi-beam continuous progressive heating, increases the total energy of injected laser in unit time and rapidly heats a plurality of quenching units on the surface of a workpiece by controlling the quenching power, heating time, interval distance and irradiation times of the multi-beam to the quenching units, and finishes phase change hardening at the last heating position, and the multi-beam depends on the accumulated thermal effect generated by the interval continuous laser heating and obtains higher production efficiency and deeper hardened layer by a heat conduction mode.

The continuous progressive heating selective laser quenching method provided by the invention changes the existing single-beam laser heating mode into a multi-beam laser heating mode, changes the heating and heat transfer processes of the existing laser quenching process, can avoid the phenomena of melting, shallow depth of hardened layer and the like easily caused on the surface of a metal material when high-power-density laser quenching is adopted, can obviously improve the depth of laser quenching, and can effectively solve the technical problem of low production efficiency of the existing laser quenching process. The invention can also adopt a plurality of rows of laser beam arrays to simultaneously carry out laser quenching on a plurality of rows of quenching units, thereby further improving the efficiency of laser quenching.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.