As an emerging technology, laser processing technology has developed rapidly in recent years and is widely used in cutting, welding, etching, marking, drilling, heat treatment and other scenarios of various materials.
With the wide application of laser processing technology, laser processing equipment has also been developed rapidly. Based on the various advantages of laser processing, in terms of metal material processing, laser cutting equipment is widely replacing traditional plasma cutting, engraving machines and CNC punching machines and other processing equipment.
A typical planar laser cutting machine tool can realize cutting of various metal materials, including various types of steel plates, aluminum alloys, copper, titanium alloys, etc. During the processing, the laser beam is perpendicular to the normal direction of the surface of the plate to be processed.
The typical laser cutting process cannot realize the processing of sink holes and grooves. If the sink holes or grooves need to be processed later, they must be repositioned and processed by other equipment. In this case, the processing efficiency and processing accuracy cannot be well guaranteed.
This paper introduces a laser processing technology based on the surface cutting machine tool to process the counterbore and groove of typical metal materials.
This technology uses the characteristics of high energy density of the laser to quickly melt the material, and then quickly blow the molten material away through the high-pressure airflow, realizing the processing of sink hole and groove.
Countersunk processing platform scheme
Main hardware introduction of laser cutting machine
Laser cutting machine hardware platform includes numerical control system, servo drive system, mechanical platform and auxiliary equipment, laser and auxiliary equipment, cutting head and auxiliary equipment, integrated electrical cabinet, etc., as shown in Figure 1.
Introduction of laser cutting machine software solution
The software system of CNC laser cutting machine mainly includes 5 parts:
⑴The Human-Machine Interface (HMI) is developed with high-level language to realize the data interaction between the operator and the CNC system.
⑵PLC program to realize the control of each component of the machine tool, including various logic control and process control.
(3) NC subroutines, including various technological processes, to realize various processing functions.
⑷ Cutting process database, including cutting parameters and process parameters of various plates.
⑸CAM software, which converts CAD drawings into processing program codes that the machine tool can recognize.
Introduction of cutting processes
- Initialize various parameters;
- Set the workpiece coordinate system;
- Call cutting database;
- Quickly move to the perforation position;
- Call the perforation parameters;
- Emit light and air, and begin to perforate;
- The perforation is in progress;
- Call cutting parameters;
- Cut parts according to the path;
- When the current path is cut, turn off the light;
- Repeat steps 4 to 10;
- The whole part is cut.
Counterbore machining plan
The functional flow of cyclone countersinking is to cut a bottom hole with a diameter of D1 first, then the cutting head is raised to a height of H1, and the radius is expanded by D2/2 on the basis of the radius of the bottom hole to carry out countersinking processing, and finally the bottom hole is cut again to complete After cutting, proceed to the next contour, as shown in figure 2.
Specific processing flow: cut the bottom hole → call parameters → perforate → cut the bottom hole → end the bottom hole cutting → quickly process the groove → call the processing parameters of the groove → process the groove → end the groove processing → process the bottom hole again → call the processing again Bottom hole parameters→re-processing the bottom hole→end of bottom hole processing→completion of countersunk hole processing. The counterbore after machining is shown in figure 3.
Research on technological parameters of counterbore
The laser cutter parameters are set as followed:
- Laser frequency: 500Hz.
- Laser duty cycle: 100%.
- Gas type: keep consistent with the cutting gas.
- Gas pressure: when cutting carbon steel plate with oxygen, the air pressure is 5bar; when cutting aluminum alloy with air, the gas type is high nitrogen, and the air pressure is set to the maximum.
- Cutting nozzle gap: when oxygen cutting carbon steel plate, set it to 35mm; when air cutting aluminum alloy, set it to 15mm.
- Cutting power: It can be adjusted according to the depth requirements; when cutting carbon steel plate with oxygen, set it to 2000W; when cutting aluminum alloy with air, set it to 4000W.
- Cutting speed: It can be adjusted according to the requirements of the depth, and the setting is about 3000mm/min.
- Compensation radius: when oxygen cutting carbon steel plate, set it to 2.5mm; when air cutting aluminum alloy, set it to 0.6mm (fine adjustment is possible).
- Focus position: when oxygen cutting carbon steel plate, set it to +9mm; when air cutting aluminum alloy, set it to +19mm (fine adjustment is possible).
Key accuracy control of counterbore
The main size data of the counterbore are shown in figure 4 (section view). The key parameters of the dimensional accuracy of the counterbore: the bottom hole size dh, the surface hole size Dc, and the depth t of the counterbore part.
Bottom hole size dh precision control related technologies. Bottom hole precision control mainly consists two parts: motion path and beam diameter. The core control code is as followed:
Among them, D_IN is the diameter of the bottom hole, and D_BEAM is the diameter of the slit.
⑵Surface hole size Dc, depth t precision control technology of counterbore part. The core control code is as followed:
Z_UP is the processing height of the surface hole, and the relevant accuracy can be controlled by this parameter; D_BURN is the diameter of the surface hole, and the dimensional accuracy can be controlled by this parameter; NOW_BURN is the number of surface hole processing, and the depth can be controlled by this parameter.
Through the realization of counterbore processing function, the application of plane laser cutting can be effectively broadened, the scope of use of plane laser cutting machine tools can be improved, and the bevel cutting machine tool and three-dimensional five-axis machine tool can be replaced to a certain extent, reducing the equipment investment cost of the enterprise and improving the processing efficiency.