In the multi-layer structure construction of the upper module of the offshore oil platform, the H-shaped steel lap joint structural parts of various specifications account for 75%~80% of the total work of the platform construction, and the weight accounts for about 70% of the total weight of the platform. Due to the various forms and complicated figures of the H-shaped steel lap joints, it is necessary to complete the cutting line, the cutting curve, the cutting arc, the cutting process hole and the opening groove on three different planes of one web and two wings. A variety of cutting operations.
Using CNC blanking technology and equipment to cut H-shaped steel end, can achieve high quality, high efficiency, automation and low cost flame cutting operation 111. 1 CNC flame cutting and cutting overall scheme H-shaped steel CNC flame cutting and cutting overall The plan is as follows.
In order to improve the cutting efficiency, three cutting blades are used to simultaneously cut the two wings and one web of the H-shaped steel.
The numerical control technology is used to realize the cutting trajectory of the cutting gun and the cutting flame control. Three sets of CNC systems are used to control the three cutting guns separately, and the control of the cutting gun action relationship is realized through programming. Because of the space motion, the movement of each cutting gun is a three-coordinate linkage.
The numerical control programming method is used to solve various forms of H-shaped steel end profiles that need to be cut.
The upper computer visual programming system is used to realize the unified management of three sets of numerical control systems and the visual parametric programming design of various cutting shape ends.
2 The main parameters of the CNC flame cutting machine determine the main design parameters and technical requirements of the equipment as follows.
The large section is 1500X1000X5mm, the smallest section is the leather cutting H-shaped steel, the maximum length is 12000mm. The cutting arm can move in the range of 12000mm, stop at any position, and the moving speed is steplessly adjusted within 015m/min.
Axis movement stroke: The three coordinate axes movement stroke meets the requirements of the above-mentioned end cutting range, and the cutting operation of the 304560 and other bevels can be manually performed.
Axis movement speed: The movement speed of the three coordinate axes is 0 5m/mir continuous, and the NC programming is adjustable.
Nine-track interpolation function: spatial line and plane circular interpolation.
Auxiliary function: The program controls the flame adjustment, including preheating, cutting, waiting and turning off the fire.
Machining accuracy: the dimension error of the slit in each coordinate direction is less than 0.5mm. The surface roughness is less than RQ0. The motion accuracy of the coordinate axis: the positioning error within the full-length stroke of each coordinate is less than 0.2mm. Programming interface: using the upper computer graphics to interact with the human-machine interface Visual graphical parameter programming.
Machining automation: automatic positioning after loading, manual position finding and tool setting at the incision, length adjustment between semi-automatic two incisions, automatic placement after workpiece cutting.
3 The overall layout of the machine tool is placed horizontally, the two wings are upright and the web is horizontal.
Thus, the overall layout of the cutting device is a horizontal layout.
The moving parts include three sets of cutting equipment, three sets of numerical control devices, and cutting arms. The moving parts only make the positioning adjustment movement, and do not move when cutting, so there is no strict requirement for the movement precision, as long as it can realize automatic walking and rough searching. Just right. The precise positioning of the cutting gun is realized by a fixed scale on the guide rail or a special quick positioning ruler for the cutting gun. The longitudinal movement of the cutting arm is guided by a single H-shaped steel guide rail and a roller, and the friction wheel is driven.
Since the weight of the entire cutting portion is not large, the cutting arm portion adopts a single-column cantilever structure to simplify the structure and facilitate the loading and unloading.
In order to facilitate the longitudinal adjustment of the H-beam, the workbench is supported by a H-beam in the form of a roller, and a plurality of identical unit tables are combined into a long-length workbench to facilitate the manufacture and installation of the workbench. On the workbench, there are devices for placing the H-beams to be placed, buffered, longitudinally and laterally positioned, and clamped.
4 CNC flame cutting and cutting process design The H-shaped steel end that needs to be cut has two types of convex and notch.
The cutting process design is mainly to determine the control sequence of the three CNC cutting guns, the movement trajectory and the cutting flame.
4.1 Cutting gun numerical control motion scheme Determination According to the numerical control blanking process analysis, the spatial trajectory of the cutting nozzle is the forming motion of the end cutting processing. This is a more complex motion, and the three-coordinate linkage can get out of its spatial motion trajectory. The coordinate system setting of the three cutting guns is as shown. Since the three cutting guns are respectively located in three parallel three-axis linkage coordinate systems, the coordinate system is set as follows: the overall (including the workpiece) coordinate system is XY left gun XfeY2 left and right guns are Xfef2 right, and the gun is on f1z.
In addition to the forming movement, in order to cut the end shape of a whole H-shaped steel (12m long) at different cross-section positions, it is also necessary to have an auxiliary movement of the H-shaped steel relative to the cutting gun, which is parallel to the X-axis, and is referred to as U-shaped. For longitudinal movement; in addition to cutting the groove at different angles, the three cutting guns also need to have a swinging angle of movement (manually completed) called pendulum movement.
Three sets of Y (Y, Y right, Y upper) axis motion mechanisms of three cutting guns are arranged on the same beam to simplify the machine structure; the cut H-shaped steel is fixed, and the three sets of cutting devices move rapidly along the U-axis. To realize the initial location of the cutting point, the gun uses a special ruler to accurately locate the way to realize the rapid positioning of the three cutting guns, and determine the movement function of the cutting machine: W/UYff/T, where W is H-shaped steel, T For cutting the gun, i left, right, up. The motion function diagram is as shown.
4.2 The numerical control blanking process design of the convex mouth and the movement path of the three cutting guns are as shown. The CNC cutting movement process is as follows (the following CNC cutting process is completely in the order of numbering).
1) Firstly, the cutting arm with three cutting guns is mounted by the longitudinal (X-direction) moving device along the longitudinal rail parallel to the Hi steel being cut, and the whole is quickly moved to the vicinity of the H-shaped steel point to be cut (within 0 mm) Complete fast and coarse positioning of the three cutting guns.
2 The control of the manual pulse wheel is controlled by a special scale, and the center point of the three cutting guns is moved to the starting point of the cutting (inch point) to realize the precise positioning of the three cutting guns.
With the zero return control button, the three cutting guns are returned to their original coordinate origins, and the heat preservation fire is automatically ignited, so that each cutting gun flame is in a waiting state.
The left and right guns simultaneously advance to the respective wing starting point A point A, and the preheating preheating time is determined by the test. After the preheating is completed, the left and right gun flames are automatically converted into the cutting flame state, respectively Cutting motion on both sides of the wing. The left gun starts from point A straight line to point B right shot and starts to move from point A straight line to B. left and right gun simultaneously from point B point B straight line work to point point C point C left and right gun simultaneously by point C point C straight line works to point D point D. After that, the left and right gun flames are automatically converted into waiting state, and respectively retreat to the middle of the respective coordinate starting point and the wing cutting point, waiting for the subsequent cutting groove process.
At 8 o'clock, the gun is shot (the web breaks into the cutting point F and preheats the cutting point.
After the preheating is completed, the flame of the gun is turned into a cutting state, and the cutting of the web is started. From the point F, the thread is pushed to the point G and the gun is pressed by the point [the circular arc into the point H (cutting the process hole).
The shot is taken from the point straight line back to point H to complete the left process hole cutting.
The gun flame is automatically turned into a warm-up state, and then quickly enters the point to stay and preheat.
After the preheating is completed, the flame of the gun is automatically turned into the cutting state, and the cutting of the protruding portion of the protruding head is completed from the point straight line to the point of the gun from the point M straight line to the point N.
The gun continues to move from the point N straight line to the point O. The gun passes from the point P arc to the point Q to complete the right process hole cutting. After that, the gun flame automatically turns into the waiting state, and retreats to the middle point, waiting.
Thereafter, the left and right gun flames are automatically converted to a heated state, and at the same time fast forward to point B point B and stay preheated.
After the preheating is completed, the left and right gun flames are turned into a cutting state, and the remaining cutting of the web is started to be cut. The left and right guns start at the same time from the point B point B straight line to the point E point E. The cutting part of the cutting head is completed, and the groove cutting is performed below. The left and right gun flames turn to the waiting state, and each retreats to their respective waiting points and waits.
Manually swing and adjust the left and right guns and the gun, so that the three cutting guns can obtain the angle required for the bevel cutting.
The three cutting gun flames are turned into the preheating state, and the left gun is fast forwarded to the point A. The right gun is fast forwarded to the point A. The gun fast forwards to the point K to stay warm.
After the preheating is completed, the three cutting gun flames are each turned into a cutting state, and the left gun immediately starts to move from the point At line to the point E. The right gun starts immediately from the point A straight line to the point E. The gun immediately starts from the point K straight line. When the work enters the point L, the groove is cut, the three cutting guns are extinguished, and they are retracted to their respective coordinate origins.
The notch blanking process is similar to the nose, and will not be described here.
5 cutting process motion analysis 5.1 three cutting gun action sequence requirements are known: two of the three cutting guns are used to cut two parallel wings, the two wings are separated by a web There is a long distance (cutting range is between 300 and 1200). Therefore, the two cutting guns can work at the same time without any influence on each other. See, however, the gun for cutting the web and the left and right guns. It is a vertical relationship. If three cutting guns work at the same time, it is very likely that the flames of the left and right guns of the cutting wing will be directly sprayed onto the upper part of the cutting web, which will burn through the tip of the gun, and there is a serious gas explosion. Hidden accidents. Therefore, it must be ensured in the cutting process that the gun of the cutting web and the gun of the cutting flap cannot work simultaneously, as shown.
5.2 Three-cutter gun multi-coordinate linkage control implementation 121 The coordinate linkage number of three cutting guns is 3X3. Although each gun is planar two-dimensional linkage during cutting movement, each gun needs to complete the position finding and zero return before and after cutting. Wait for exercise. Therefore, each gun actually needs three-coordinate linkage. In addition, there is a logical sequence of actions between the gun and the gun. Therefore, the three cutting guns of the whole device can be regarded as a nine-coordinate linkage. You can use a CNC system to control the three cutting guns in nine coordinates. The advantage is that the number of sets used in the CNC system is small and the hardware cost is low. The disadvantages are complicated in programming, debugging and on-site modification of parameters, and guns and guns. The mutual influence is great. Three sets of CNC systems can also be used to control three cutting guns. The advantages are reliable control, relatively independent gun control, simple and fast programming and field modification parameters. The disadvantage is that the hardware investment is large, and the main and auxiliary machine management system needs to be set. .
The machine adopts three sets of systems to control three cutting guns respectively. One CNC system controls the other two systems as the main control system, and each system can be adjusted and used separately to adapt to the complex and random on-site cutting conditions. There are many adjustments, high requirements for system control reliability, and high anti-interference requirements between the gun and the gun.
In addition, this machine adopts the upper computer management system, realizes fast, simple and offline programming of cutting graphics through dedicated visual graphic parameter programming software, and can perform simulation test on it to ensure the correctness of the program, as long as the inspection is qualified. The program is transferred to the main CNC system, which can realize the three-gun linkage cutting movement of the system. The visual programming software interface is shown.
5.3 Fast and precise positioning of different cutting point positions As can be seen from the figure: the H-shaped steel before cutting is 12m long, and it is placed on the worktable without moving. When cutting the different positions on it, it moves through the longitudinal (X-direction). The cutting arm is positioned to achieve this. Since the H-beam is a welded piece, it is long and has a large deformation. The geometric accuracy of the entire shape is very low. When cutting each position, if the cutting gun is used to directly return to the coordinate origin (absolute coordinate origin method), the method of finding the position To locate, there will be a lot of error when cutting, and there will always be scrap. The machine uses the fast coarse positioning and the accurate positioning method of the scale to solve the problem (relative coordinate origin method), that is, the cutting position point (allowing error is 100) is initially found by the rapid movement of the cutting arm on the longitudinal rail to be placed at the cutting point. The special scale is used as the reference point, and the displacement of the three cutting guns is controlled by the manual pulse feeder to achieve fast and precise positioning, as shown.
5.4 Matching of flame parameter control and feed motion Each movement of the cutting gun has a close match with the condition of the flame. The flame of the cutting gun has two states: heating fire and cutting fire, which is achieved by controlling the oxygen supply of the cutting barrel under certain conditions of acetylene supply. A heating fire is used when the cutting gun is in a cutting waiting state, a heating state before cutting, and a cutting fire is used when the cutting gun is in a cutting state. Therefore, the gas supply amount of oxygen is divided into two types: small and large.
The requirements for cutting the flame fit are as follows: when the cutting gun starts to move rapidly from the coordinate starting point to the cutting point, the cutting gun automatically starts to heat the flame; when the cutting gun reaches the cutting starting point and starts heating the cutting starting point, the cutting gun still uses the heating flame, and Stay at the starting point of the cutting for a few seconds until the heating process is completed (the residence time varies depending on the thickness of the sheet, the material, etc., determined by prior process tests). When the cutting gun begins to cut from the cutting starting point, the cutting gun is automatically converted into a cutting flame, and Start cutting the cutting track and complete the cutting; after the cutting gun completes the cutting, the flame is automatically converted into a heating fire, and the cutting gun quickly retreats to the coordinate origin or some intermediate point, waiting for the next cutting task.
This machine adopts the form of M command embedded in the CNC system, and realizes the above requirements of flame change control by controlling the logical relationship between the opening and closing of the nine solenoid valves mounted on the three cutting guns.
6 Conclusion The numerical control flame cutting machine manufactured by the above technical scheme has been applied to the construction of the offshore platform engineering of CNOOC Oil Construction Engineering Company, and has played an active and effective role. The H-shaped steel end after the NC cutting and cutting is completed is as shown.
The numerical control flame cutting device can better solve the problem of automatic cutting of the H-shaped steel end in the construction of the offshore platform, realizing the high-performance numerical control without cutting, cutting without cutting, high cutting quality and accurate geometric shape before cutting. The blanking production significantly improves the quality of the cutting and production efficiency, and effectively reduces the production cost to fill the domestic blank of the numerical control equipment.
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