Laser power output control method for SLM printer

Abstract

The present invention discloses a method for regulating the laser power output of an SLM printer, belonging to the technical field of 3D printing, including establishing an adaptive server, presetting three stages of the temperature field, and respectively calculating the laser power P of different stages of the temperature field i , looking up the table in the laser power step-by-step adjustment value table to find the laser power P i corresponding power threshold in the laser power step-by-step adjustment value table, and taking the threshold average value corresponding to the power threshold as the final power adjustment result, which solves the technical problem of using three stages to distinguish the processing process and implementing different-stage and different-level regulation and control of the laser power of the SLM printer. The present invention regulates the power output according to the requirements of different stages, improves the printing accuracy and efficiency, its output power is adjusted step by step, the operation is simple, the regulation and control requirements for laser control are low, and the adaptability is strong. The present invention also adds the environmental humidity parameter while considering the temperature parameter, improving the processing accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of 3D printing, and in particular relates to a laser power output control method of a SLM printer. Background Art

[0002] SLM 3D printer is a high-precision 3D printing technology, and the laser control technology involved in the control system is crucial.

[0003] For the laser power output regulation of SLM printers, the current traditional technology mostly uses closed-loop feedback control: closed-loop feedback control can monitor the actual situation of laser power output through sensors, compare the actual output value with the set value, and adjust the laser power output in time to ensure stable and accurate output.

[0004] However, in the current traditional technology, the regulation of laser power output mostly does not adopt multi-stage regulation, that is, the output power of the laser is not divided into different stages for regulation, which affects the final printing accuracy of the printer. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling the laser power output of an SLM printer, which solves the technical problem of using three stages to distinguish the processing process and implementing different stages and different levels of control on the laser power of the SLM printer.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A method for controlling the laser power output of a SLM printer comprises the following steps:

[0008] Step 1: Establish an adaptive server, which communicates with the SLM printer through a data line;

[0009] Step 2: The adaptive server presets three stages for the temperature field generated during the molten pool radiation process according to the temperature, and the three stages are preheating stage, heating stage and holding stage respectively;

[0010] Creating a laser power step-by-step adjustment value table, the laser power step-by-step adjustment value table includes several power thresholds, and calculating a threshold value average value corresponding to each power threshold;

[0011] Step 3: Turn on the SLM printer, and the adaptive server reads the temperature data and humidity data generated during the molten pool radiation process collected by the SLM printer in real time, and determines which stage of the temperature field is in the three stages according to the temperature data;

[0012] Step 4: Calculate the laser power P at different stages of the temperature field according to the following formula: i :

[0013] P i =P j +{K1×|TT x |+K2×|RH-RH y |}÷t z ;

[0014] Among them, P i The value of i is i = {pr, up, ho}, which represents the actual laser power in the preheating stage as P pr , the actual laser power in the heating stage is P up The actual laser power in the holding stage is P ho ;P j The value of j is j = {0, 1, 2}, which respectively indicates that the expected laser power in the preheating stage is P0, the expected laser power in the heating stage is P1, and the expected laser power in the holding stage is P2; K1 and K2 are environmental correction coefficients; T is the current temperature, RH is the current humidity, T X The value of x is x={0, 1, 2}, which respectively indicates that the expected temperature in the preheating stage is T0, the expected temperature in the heating stage is T1, and the expected temperature in the holding stage is T2; RH y The value of y is y={0, 1, 2}, which respectively indicates that the expected humidity in the preheating stage is RH0, the expected humidity in the heating stage is RH1, and the expected humidity in the holding stage is RH2; t z The value of z is z = {pr, up, ho}, which represents the laser on time in the preheating stage as t pr , the expected laser on time during the heating phase is t up , the expected laser on time in the hold phase is t ho ;

[0015] Step 5: Look up the laser power step-by-step adjustment value table to find the laser power P calculated in step 4. i Corresponding to the power threshold corresponding to the laser power step-by-step adjustment value table, the threshold value average value corresponding to the power threshold is used as the final power adjustment result;

[0016] Step 6: The adaptive server sends the final power adjustment result to the SLM printer. The SLM printer adjusts the laser output power according to the final power adjustment result. At the same time, the adaptive server displays the real-time status of the temperature field and the final power adjustment result through the display screen.

[0017] Preferably, when executing step 2, the data cable is a network cable, a USB data cable or a 485 data cable.

[0018] Preferably, when executing step 3, the specific steps are as follows:

[0019] Step 3-1: According to the three stages preset in step 2, a list of temperature thresholds corresponding to the preheating stage, the heating stage and the holding stage is established;

[0020] Step 3-2: The SLM printer collects the temperature data of the molten pool and the humidity data of the environment through its own photoelectric sensor and humidity sensor. The adaptive server reads the temperature data and humidity data in real time and establishes a temperature field model based on the temperature data and humidity data.

[0021] Step 3-3: According to the temperature data in the temperature field model and in comparison with the temperature threshold list, determine which stage of the three stages the temperature field is in.

[0022] Preferably, when executing step 4, according to the judgment result of step 3-3, the corresponding formula is selected at different stages to calculate the laser power P i The calculation is performed, and the specific parameter values ​​are that the expected laser power P0 in the preheating stage, the expected laser power P1 in the heating stage, and the expected laser power P2 in the holding stage are all different power preset values, the expected temperature T0 in the preheating stage, the expected temperature T1 in the heating stage, and the expected temperature T2 in the holding stage are all different temperature upper limit preset values, the expected humidity RH0 in the preheating stage, the expected humidity RH1 in the heating stage, and the expected humidity RH2 in the holding stage are all different humidity upper limit preset values, and the laser on time t in the preheating stage is pr and the expected laser on time t during the heating phase up are different preset time values, indicating the expected laser on time, the expected laser on time t in the hold phase ho Calculated by laser scanning speed and scanning distance.

[0023] Preferably, the expected laser on time t during the holding phase is ho The specific calculation formula is:

[0024] t op =L÷V+K n ;

[0025] Where V is the laser scanning speed, L is the single scanning distance, K n To correct the parameters.

[0026] The laser power output control method of an SLM printer described in the present invention solves the technical problem of using three stages to distinguish the processing process and implementing different graded control of the laser power of the SLM printer at different stages. The present invention controls the power output according to the needs of different stages, thereby improving the printing accuracy and efficiency. When performing graded control on the laser, the present invention adopts a table lookup method for step-by-step adjustment of the laser power value table, and its output power is adjusted step by step, the operation is simple, the control requirements for laser control are low, and the adaptability is strong. The present invention also adds the environmental humidity parameter while considering the temperature parameter, thereby further improving the processing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the main flow chart of the present invention;

[0028] Figure 2 is a flow chart of step 3 of the present invention;

[0029] Figure 3 It is a flowchart of step S1 to step S9 of the present invention. DETAILED DESCRIPTION

[0030] like Figure 1-Figure 3 The laser power output control method of a SLM printer shown includes the following steps:

[0031] Step 1: Establish an adaptive server, which communicates with the SLM printer through a data line.

[0032] Step 2: The adaptive server presets three stages for the temperature field generated during the molten pool radiation process according to the temperature size. The three stages are preheating stage, heating stage and holding stage.

[0033] A laser power step-by-step adjustment value table is created, the laser power step-by-step adjustment value table includes several power thresholds, and a threshold value average value corresponding to each power threshold is calculated.

[0034] The data cable is a network cable, a USB data cable or a 485 data cable.

[0035] Step 3: Turn on the SLM printer, and the adaptive server reads the temperature data and humidity data generated during the molten pool radiation process collected by the SLM printer in real time, and determines which stage of the temperature field is in the three stages according to the temperature data.

[0036] The specific steps are as follows:

[0037] Step 3-1: According to the three stages preset in step 2, a list of temperature threshold values ​​corresponding to the preheating stage, the heating stage and the holding stage is established.

[0038] Step 3-2: The SLM printer collects the temperature data of the molten pool and the humidity data of the environment through its own photoelectric sensor and humidity sensor. The adaptive server reads the temperature data and humidity data in real time and establishes a temperature field model based on the temperature data and humidity data.

[0039] Photoelectric sensors and humidity sensors are conventional supporting equipment for SLM printers and are prior art, so they will not be described in detail.

[0040] Step 3-3: According to the temperature data in the temperature field model and in comparison with the temperature threshold list, determine which stage of the three stages the temperature field is in.

[0041] Step 4: Calculate the laser power P at different stages of the temperature field according to the following formula: i :

[0042] P i =P j +{K1×|TT x |+K2×|RH-RH y |}÷t z ;

[0043] Among them, P i The value of i is i = {pr, up, ho}, which represents the actual laser power in the preheating stage as P pr , the actual laser power in the heating stage is P up The actual laser power in the holding stage is P ho ;P j The value of j is j = {0, 1, 2}, which respectively indicates that the expected laser power in the preheating stage is P0, the expected laser power in the heating stage is P1, and the expected laser power in the holding stage is P2; K1 and K2 are environmental correction coefficients; T is the current temperature, RH is the current humidity, T X The value of x is x={0, 1, 2}, which respectively indicates that the expected temperature in the preheating stage is T0, the expected temperature in the heating stage is T1, and the expected temperature in the holding stage is T2; RH y The value of y is y={0, 1, 2}, which respectively indicates that the expected humidity in the preheating stage is RH0, the expected humidity in the heating stage is RH1, and the expected humidity in the holding stage is RH2; t z The value of z is z = {pr, up, ho}, which represents the laser on time in the preheating stage as t pr , the expected laser on time during the heating phase is t up , the expected laser on time in the hold phase is t ho .

[0044] In order to make the environmental coefficient change smoothly during calculation, K1 and K2 are added as environmental correction coefficients in this embodiment. K1 and K2 respectively reflect the difficulty of changing the temperature and the difficulty of changing the humidity in the historical data. Their values ​​are obtained through historical data statistics and expressed in the form of a table.

[0045] When executing step 4, according to the judgment result of step 3-3, select the corresponding formula for the laser power P at different stages i The calculation is performed, and the specific parameter values ​​are that the expected laser power P0 in the preheating stage, the expected laser power P1 in the heating stage, and the expected laser power P2 in the holding stage are all different power preset values, the expected temperature T0 in the preheating stage, the expected temperature T1 in the heating stage, and the expected temperature T2 in the holding stage are all different temperature upper limit preset values, the expected humidity RH0 in the preheating stage, the expected humidity RH1 in the heating stage, and the expected humidity RH2 in the holding stage are all different humidity upper limit preset values, and the laser on time t in the preheating stage is pr and the expected laser on time t during the heating phase up are different preset time values, indicating the expected laser on time, the expected laser on time t in the hold phase ho Calculated by laser scanning speed and scanning distance.

[0046] Expected laser on time t during the hold phase ho The specific calculation formula is:

[0047] t op =L÷V+K n ;

[0048] Where V is the laser scanning speed, L is the single scanning distance, K n is the correction parameter, K n It is a preset error value, which represents the error between the actual laser on time and the theoretical laser on time at the set speed. The error value is calculated through historical data.

[0049] Step 5: Look up the laser power step-by-step adjustment value table to find the laser power P calculated in step 4. i Corresponding to the power threshold in the laser power step-by-step adjustment value table, the threshold average value corresponding to the power threshold is used as the final power adjustment result.

[0050] Step 6: The adaptive server sends the final power adjustment result to the SLM printer. The SLM printer adjusts the laser output power according to the final power adjustment result. At the same time, the adaptive server displays the real-time status of the temperature field and the final power adjustment result through the display screen.

[0051] The following is a specific processing flow of this embodiment:

[0052] Step S1: Establish an adaptive server, and the adaptive server communicates with the SLM printer via a data line.

[0053] Step S2: the adaptive server presets three stages for the temperature field generated during the molten pool radiation process, and the three stages are a preheating stage, a heating stage and a holding stage.

[0054] Step S3: Turn on the SLM printer, and the adaptive server reads the temperature and humidity data generated during the molten pool radiation process collected by the SLM printer in real time.

[0055] Step S4: Determine whether it is in the preheating stage according to the temperature data: if it is not in the preheating stage, execute step S6; in the preheating stage, adaptively calculate the laser power P of the SLM printer in the preheating stage according to the following formula: pr :

[0056] P pr =P0+{K1×|T-T0|+K2×|RH-RH0|}÷t pr ;

[0057] Among them, P pr is the actual laser power in the preheating stage, T is the current temperature, T0 is the expected temperature in the preheating stage, RH is the current humidity, P0 is the expected laser power in the preheating stage, RH0 is the expected humidity in the preheating stage, K1 and K2 are environmental correction coefficients, and t pr This is the adjustment time for the preheating phase.

[0058] Look up the table in the laser power step-by-step adjustment value table and find P pr Corresponding to the power threshold in the laser power step-by-step adjustment value table, the threshold value average value corresponding to the power threshold is used as the final power adjustment result, and the final power adjustment result is output to the SLM printer for adjustment.

[0059] Step S5: Adjust the laser power P according to the method of step S4 pr , until the current temperature reaches the expected temperature T0 of the preheating stage, that is, the heating of the preheating stage is completed and the heating stage begins.

[0060] Step S6: Determine whether it is in the heating stage according to the temperature data: if it is not in the heating stage, execute step S8; in the heating stage, adaptively calculate the laser power P of the SLM printer in the preheating stage according to the following formula: up :

[0061] P up =P1+{K1×|T-T1|+K2×|RH-RH1|}÷t up;

[0062] Among them, P up is the actual laser power in the heating stage, T is the current temperature, T1 is the expected temperature in the heating stage, RH is the current humidity, P1 is the expected laser power in the heating stage, RH1 is the expected humidity in the heating stage, K1 and K2 are environmental correction factors, t up is the adjustment time for the heating phase.

[0063] Look up the table in the laser power step-by-step adjustment value table and find P up Corresponding to the power threshold in the laser power step-by-step adjustment value table, the threshold value average value corresponding to the power threshold is used as the final power adjustment result, and the final power adjustment result is output to the SLM printer for adjustment.

[0064] Step S7: Adjust the laser power P according to the method of step S4 pr , until the current temperature reaches the expected temperature T0 of the preheating stage, that is, the heating of the heating stage is completed and enters the holding stage.

[0065] Step S8: Determine whether it is in the holding stage according to the temperature data: if it is not in the holding stage, execute step S9; in the holding stage, calculate the laser on time t according to the scanning speed V of the laser scanning op :

[0066] t op =L÷V+K n ;

[0067] Where V is the laser scanning speed, L is the single scanning distance, K n is the correction parameter;

[0068] The laser power P in the holding phase is calculated according to the following formula ho :

[0069] P ho =P2+{K1×|T-T2|+K2×|RH-RH2|}÷t op ;

[0070] Among them, P ho is the actual laser power in the holding phase, T is the current temperature, T2 is the expected temperature in the holding phase, RH is the current humidity, P2 is the expected laser power in the holding phase, RH2 is the expected humidity in the holding phase, K1 and K2 are environmental correction coefficients, and t ho In the holding stage, the laser is turned on for a certain period of time;

[0071] Look up the table in the laser power step-by-step adjustment value table and find P hoCorresponding to the power threshold in the laser power step-by-step adjustment value table, the threshold value average value corresponding to the power threshold is used as the final power adjustment result, and the final power adjustment result is output to the SLM printer for adjustment.

[0072] Step S9: Repeat steps S4 to S8 until the processing task is completed. During the processing, the adaptive server displays the real-time status of the temperature field and the final power adjustment result on the display screen in real time.

[0073] The laser power output control method of an SLM printer described in the present invention solves the technical problem of using three stages to distinguish the processing process and implementing different graded control of the laser power of the SLM printer at different stages. The present invention controls the power output according to the needs of different stages, thereby improving the printing accuracy and efficiency. When performing graded control on the laser, the present invention adopts a table lookup method for step-by-step adjustment of the laser power value table, and its output power is adjusted step by step, the operation is simple, the control requirements for laser control are low, and the adaptability is strong. The present invention also adds the environmental humidity parameter while considering the temperature parameter, thereby further improving the processing accuracy.

Claims

1. A method for controlling the laser power output of a SLM printer, characterized in that: The steps include: Step 1: Establish an adaptive server, which communicates with the SLM printer through a data line; Step 2: The adaptive server presets three stages for the temperature field generated during the molten pool radiation process according to the temperature, and the three stages are preheating stage, heating stage and holding stage respectively; Creating a laser power step-by-step adjustment value table, the laser power step-by-step adjustment value table includes several power thresholds, and calculating a threshold value average value corresponding to each power threshold; Step 3: Turn on the SLM printer, and the adaptive server reads the temperature data and humidity data generated during the molten pool radiation process collected by the SLM printer in real time, and determines which stage of the temperature field is in the three stages according to the temperature data; Step 4: Calculate the laser power P at different stages of the temperature field according to the following formula: i : P i =P j +{K1×|TT x |+K2×|RH-RH y |}÷t z ; Among them, P i The value of i is i = {pr, up, ho}, which represents the actual laser power in the preheating stage as P pr , the actual laser power in the heating stage is P up , the actual laser power in the holding stage is P ho ;P j The value of j is j = {0, 1, 2}, which respectively indicates that the expected laser power in the preheating stage is P0, the expected laser power in the heating stage is P1, and the expected laser power in the holding stage is P2; K1 and K2 are environmental correction coefficients; T is the current temperature, RH is the current humidity, T X The value of x is x={0, 1, 2}, which respectively indicates that the expected temperature in the preheating stage is T0, the expected temperature in the heating stage is T1, and the expected temperature in the holding stage is T2; RH y The value of y is y={0, 1, 2}, which respectively indicates that the expected humidity in the preheating stage is RH0, the expected humidity in the heating stage is RH1, and the expected humidity in the holding stage is RH2; t z The value of z is z = {pr, up, ho}, which represents the laser on time in the preheating stage as t pr , the expected laser on time during the heating phase is t up , the expected laser on time in the hold phase is t ho ; Step 5: Look up the laser power step-by-step adjustment value table to find the laser power P calculated in step 4. i Corresponding to the power threshold corresponding to the laser power step-by-step adjustment value table, the threshold value average value corresponding to the power threshold is used as the final power adjustment result; Step 6: The adaptive server sends the final power adjustment result to the SLM printer. The SLM printer adjusts the laser output power according to the final power adjustment result. At the same time, the adaptive server displays the real-time status of the temperature field and the final power adjustment result through the display screen.

2. The laser power output control method of a SLM printer according to claim 1, characterized in that: When executing step 2, the data cable is a network cable, a USB data cable or a 485 data cable.

3. The laser power output control method of a SLM printer according to claim 1, characterized in that: When executing step 3, the specific steps are as follows: Step 3-1: According to the three stages preset in step 2, a list of temperature thresholds corresponding to the preheating stage, the heating stage and the holding stage is established; Step 3-2: The SLM printer collects the temperature data of the molten pool and the humidity data of the environment through its own photoelectric sensor and humidity sensor. The adaptive server reads the temperature data and humidity data in real time and establishes a temperature field model based on the temperature data and humidity data. Step 3-3: According to the temperature data in the temperature field model and in comparison with the temperature threshold list, determine which stage of the three stages the temperature field is in.

4. The laser power output control method of a SLM printer as claimed in claim 3, characterized in that: When executing step 4, according to the judgment result of step 3-3, select the corresponding formula for the laser power P at different stages i The calculation is performed, and the specific parameter values ​​are that the expected laser power P0 in the preheating stage, the expected laser power P1 in the heating stage, and the expected laser power P2 in the holding stage are all different power preset values, the expected temperature T0 in the preheating stage, the expected temperature T1 in the heating stage, and the expected temperature T2 in the holding stage are all different temperature upper limit preset values, the expected humidity RH0 in the preheating stage, the expected humidity RH1 in the heating stage, and the expected humidity RH2 in the holding stage are all different humidity upper limit preset values, and the laser on time t in the preheating stage is pr and the expected laser on time t during the heating phase up are different preset time values, indicating the expected laser on time, the expected laser on time t in the hold phase ho Calculated by laser scanning speed and scanning distance.

5. The laser power output control method of a SLM printer as claimed in claim 4, characterized in that: Expected laser on time t during the hold phase ho The specific calculation formula is: t op =L÷V+K n ; Where V is the laser scanning speed, L is the single scanning distance, K n To correct the parameters.

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