2D laser cutting machine cutting round tube
Three-tube intersecting multi-tube intersecting crossover butt joint equal-diameter intersecting belt plus 9-plate branch pipe Jingtou oblique cross-section main pipe branch two-excitation head outer ring pipe intersecting branch pipe head inner ring pipe intersecting branch pipe Jingtou City and flat inner corner intersecting wall flange The hole is chamfered to force the oil tube of the oil industry, and various holes are cut on the cylindrical surface of the tube, and ammunition is placed in the hole. It is a projection of a type of bullet tube of a perforating bomb factory.
The laser cutting machine control system (CNC) requires the program to give an interpolation relationship between the X-axis (translation distance) and the A-axis (rotation angle) of the workpiece.
The function of the system is: to expand the expansion of any shape (if it is a projection, you need to first convert to the expansion), automatically converted to the NC code of the laser cutting machine. In order to achieve this goal, the problem to be solved is: the transformation from the projected image to the expanded view, the compensation of the wall thickness of the circular tube (the mapping of the outer wall to the inner wall), and according to a certain strategy, the developed image is converted into the NC code of the laser cutting machine. In order to verify the correctness of the NC code, the NC code should also be restored to graphics for simulation. Accordingly, the main modules that make up the entire system are: projection transformation and mapping, post-processor, and analog verification.
AutoCAD is the most widely used microcomputer CAD platform in the world. Therefore, the automatic programming system for circular tube cutting is selected on the AutoCAD platform, and the ADS tool is used for development programming. All features are embedded in AutoCAD and are driven by menus and toolbars to become part of AutoCAD. The CAM function is seamlessly integrated with AutoCAD and is tightly coupled.
At present, the system has been applied to multiple laser tube tube cutting machines and pipe cutting machines with good results.
Second Projection Transformation and Mapping As described above, it is necessary to convert the projection pattern on the cylindrical surface into a developed image, and map the developed image on the outer wall of the circular tube to the expanded view of the inner wall of the circular tube.
Due to the limitations of the CNC, the translation axis and the rotation axis cannot directly perform circular interpolation. Therefore, when the transformation is required, the arc needs to be converted into a polygonal line by a certain strategy (or a polygon if it is a full circle). The polygonal line must be approximated as close as possible to the circular arc. . Usually with "tolerance"
Control the accuracy of the approach (as shown below). The smaller the tolerance, the more segments are divided, and the closer to the arc: the opposite, the greater the difference between the polyline and the arc.
(1) Expand the image on the left to expand the projection, and point A on the contour. The coordinates are (XI, Y1). Xl=r is such that the expansion coordinates of each point are calculated, and the expansion process of the exhibition (2) map can be drawn, and the difference between the inner wall and the outer wall when the actual cutting is not considered. If the hole is to be placed (passed) in the hole, the effect of the wall thickness must be considered. In order to accommodate this object, the projected view of the hole in the inner wall of the finally cut circular tube must be identical to the original projected image, which is the mapping of the outer wall to the inner wall of the expanded view.
First, the projection map is mapped to the inner wall, and then the inner wall projection image is "expanded" to the outer wall, and then expanded according to this.
In the figure above, the double-dotted line is the projected image, and the solid line is the expanded view after the mapping. It is known that the wall thickness is t, the coordinates of the P1 point are (XI, Y1), and the coordinates of the corresponding points on the map are P2. The post-processor (1) outlines that the function of the post-processor is to generate the optical cutter NC code.
For the convenience of handling, the intersecting lines in the circular tube cutting are separately proposed. In addition to this, you must be able to handle arbitrary graphics.
Obtaining AutoCAD graphics entity data and ensuring a constant synthetic cutting speed is key. In addition, the removal of overlapping lines, the optimal sequencing of the cutting path, the adaptation of different CNCs, etc., are all the meanings of the post-processor.
Two circular tubes, one for the main pipe and one for the branch pipe. The main pipe is intersected by the holes on its cylindrical surface, and the branch pipes are intersected by their ends.
The two tubes intersect, there may be a spacing between the axes (0 can be considered as a special case), and the angle can vary between 0 and 90 degrees (90 degrees is the most common case). The intersecting line is spatially the same for a large (or called) small tube (or called a branch). However, when the two axes (X translation axis and A rotation axis) are cut, the developed plan is completely different.
If you want to cut any shape on the surface of the pipe, you must draw an expanded view. If it is a projected image, it will be expanded and mapped first.
When drawing the development drawing, the axial direction of the pipe is required to correspond to the X axis, and the circumferential direction corresponds to the Y axis.
(2) Obtaining Entity Data Facing the messy graphics on the screen, the key is to obtain the data of each entity. The data of the entity name ent of AutoCAD will be obtained and stored in the structure EntData.
(3) Removing the overlapping lines The function of removing overlapping lines is to detect overlapping lines, circles and arcs, and delete (merge) overlapping parts to avoid repeated cutting.
2 (4) Cutting speed For flat cutting, cutting speed is an easy to understand and solve problem.
However, when cutting a circular tube, the speed unit of the translation axis is mm/min, the speed unit of the rotation axis is °/min, and the translation axis and the rotation axis are treated as two mutually perpendicular axes. The problem arises.
3 When a speed is given by the F code (such as F2000, the final speed is 2000mm/min for the translation axis and 2000/min for the rotation axis), the CNC will decompose to two according to the movement amount of the translation axis and the rotation axis. On the shaft.
Generally, the displacement amount and speed of the shaft are given in the following format: where X200 represents the displacement amount of the translation axis X is 200 mm, A100 represents the displacement amount of the rotation axis A is 100, and F2000 represents the synthesis speed of the X-axis and the A-axis is 2000. The unit is uncertain, for a specific CNC axis, there is a corresponding speed unit.
For the sake of generality, let xx denote the displacement of the X-axis (mm), aa denote the displacement of the A-axis (°), and ff denote the velocity. Then there are the following blocks: the radius of the known pipe is r (mm), the required cutting degree is v (mm / min, according to the process requirements, this speed value is constant for a workpiece to find ff (with xx And aa changes).
1. The translation distance of the A axis La 2. The total displacement is L. 3. The time t 4. The speed component fit, fa four simulation verification simulation verification program can be said to be the inverse process of the post processor. In AutoCAD, the NC cutting code of the laser cutting machine is reduced to an unfolded view, with the X direction being the axial direction and the Y direction being the circumferential direction. The simulated graphics must be consistent with the graphics when the program was originally created.
The realization process is: analyzing the code, combining the data into the AutoCAD graphic entity, and drawing the display. In addition, the position, speed, and display of the simulated image are also considered.
(1) Code analysis and graphic display The NC program code is composed of several program segments (when displayed, one program segment behaves as one line, so it is customarily called a line).
Each block is composed as follows: block number (N) preparation function (G) feedrate (F) spindle speed (S) tool number (T) tool offset number (D) auxiliary function (M) block content The order must be maintained, but it is not necessary to include this information.
When performing simulation verification, the main thing to analyze is several preparation functions (G code): fast positioning. The maximum possible speed is determined by the machine itself. Freeway sign.
Straight line difference. The motion written after the G01 code must be a linear motion and moved at the feedrate F.
Clockwise and counterclockwise circular interpolation. The motion written after G02 or G03 must be a circular path and moved at the programmed feedrate F.
The left side of the figure below shows the NC program, and the right picture shows the corresponding analog check pattern.
Quick positioning and linear interpolation simply take the x(Y) coordinates and call the ads graphic drawing function to display them.
The circular interpolation code G2 (G03) is slightly more complicated. The format is as follows: As shown in the following figure, when AutoCAD draws an arc, the required data is (xo, yo), r, a, P. (2) The other base points pass the base point, and the simulated check pattern is placed at the specified position, and the simulation is performed. The check graphic does not overlap with the graphic on the current screen.
The speed button automatically displays the graph continuously, but you can set the pause time for viewing.
When displayed, the screen view range is continuously adjusted based on the newly generated entity.
For the sake of observation, it is necessary to display the lost motion. If "Trace Color" is set to "None", the blank trace is not displayed during the simulation check. Select any color to display the lost motion as a trace of that color.
The improvement of the five-disciplinary tools has a great effect on the labor productivity. The laser cutting machine tube cutting automatic programming system solves the problem of round tube wall thickness compensation and constant cutting speed. In the production of oil bomb tube, the effect is very obvious. The original complicated missile tube programming requires repeated cutting tests, which is not only time-consuming (three days required), laborious, and costly, and the details are not satisfactory. With this programming system, the user's NC program for the missile tube is now significantly more efficient.
After the programming problem of the laser cutting machine cutting the circular tube is solved, the 2D laser cutting machine cuts the rectangular tube problem, and the cutting programming of the rectangular tube is greatly increased compared with the round tube. The complexity of the cutting is greatly increased: the numerical control axis participating in the programming is increased to 4 For the user, the description of the cutting profile (path) is also difficult. However, the problem of rectangular tube cutting programming is solved, and the application of the extended laser cutting machine is improved, and the production efficiency is improved. great.
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