This paper introduces the main structure, main functions, technical parameters and technical characteristics of the CNC cutting machine for the box pipe, and introduces the advanced and economical advantages of the new process compared with the traditional process. : The steam collecting box welding structure of the boiler set box CNC cutting 0 刖目 power station boiler belongs to the welded structure of the internal pressure steel pipe. The characteristics of this type of structure are: to withstand the internal pressure; to open the hole in the header; when the diameter of the header is large, the insert-type joint [-a) is used, and the axis of the joint and the axis of the header are perpendicular to each other. The joint has welds in the inside and outside of the header, and is processed into a fixed angle welding groove surface at the header of the header and the end of the pipe joint; when the diameter of the header is small, the seated joint is used (-b ), the pipe joint axis and the box axis are mostly perpendicular intersecting type, a few also have oblique intersecting, eccentric intersecting type, and the end of the pipe joint is processed into a variable angle welding groove face; another kind of intersecting joint (-c) Both the header of the header and the end of the pipe joint are machined into a variable angle welded groove surface.
The processing of the groove of the header pipe is usually carried out in such a way that when the diameter of the opening is less than 80 mm, the drill can be directly selected and processed by a radial drilling machine. When the diameter of the opening is 80140mm, there must be a positioning hole before processing, that is, a small hole is drilled first, and then the hole is used as a positioning hole, and the groove is drilled step by step with a reaming knife; when the diameter of the tube is larger than 140 mm, Use a manual oxyacetylene or propane + propylene mixed gas to cut a hole, because the gas is very hard after cutting, need to grind the wheel, and then use the impact bed to mill out the groove, but the bed processing efficiency is low, the cost is high, not suitable for large-volume work, Especially when the header is long, each groove must be calibrated and aligned. After each 1 or several groove is processed, the header must be reinstalled, which is very labor-intensive, inefficient, and occupied. The venue is also larger. The processing of the header pipe joint is usually in the shape of a groove with a lathe with cam tooling, while the groove of the non-standard header pipe joint is manually gas-cut and hand-polished into a groove shape, which is very inefficient.
In order to improve the processing efficiency of the header of the header pipe, we have developed and developed the main structure and technical parameters of the CNC cutting machine for the header pipe of the CNC pipe cutting machine with a box pipe. The CNC cutting machine adopts a 3-point cantilever machine. The frame with the X, Y and Z three-axis displacement is suspended on the frame, and the X, Y and Z axes are respectively driven by the stepping motor, the AC motor and the AC servo motor, and the three-axis linkage is controlled by the industrial control machine. The trajectory of the cutting shape required to drive the cutting device out of the workpiece, wherein the Z-axis and the Y-axis are provided with a hand wheel adjusting device, which facilitates the initial positioning of the cutting nozzle. The two points at the front of the rack are the wheels that can be moved up to the station on the workpiece with a slight lifting of the frame. The front and rear pivot points are provided with 3 points of iron block. When the solenoid valve is energized, the frame can be firmly absorbed. On the workpiece, the working stability is increased. The rear fulcrum of the three fulcrums can be adjusted up and down by the screw to adapt to the tubes of different diameters. The 3-axis drive uses precision roller screws to increase the precision of rotation. The cutting nozzle is equipped with a manually operated screw adjusting tilting mechanism to adapt to the cutting edge at a certain angle, and the Z-axis up and down displacement can meet the requirements of the intersecting line drop.
See the structure of the CNC cutting machine for the box socket.
The main technical data of the equipment: (1) the projection diameter of the cutter hole is 75600mm; (3) the minimum diameter of the peach-shaped opening is 75mm; (4) the outer diameter of the cutting branch is 75600mm; (5) the spindle rotation speed is 0. *(6) The axial CNC stroke of cutting the rake angle *45*(7) cutting distance is 200mm; (9) When the angle between the direction of the cutting flame wind line and the normal direction of the cutting surface is less than or equal to 45*, the cutting precision is The main function of the 2 sets of box pipe numerical control cutting machine can cut the two intersecting vertical intersecting cylinder intersecting line holes (supervisor) head (branch); can cut the two axes obliquely intersecting cylindrical intersecting line ends (branch t); (3 〕 can cut two-axis eccentric vertical cross-column intersecting head (branch); (4) can cut two-axis eccentric inclined cross-column intersecting head (branch); (5) can cut pipe welded elbow shrimp section; can cut Intersecting the line at an angled groove; it can be rounded on the steel plate.
Ca) main line perpendicular to the axis line of the branch pipe. The main joint type of the CNC cutting machine. The main technical features of the 3 sets of box pipe CNC cutting machine adopt the cylindrical coordinate system three-axis CNC linkage, and pre-programmed according to different working modes. The corresponding NC program is stored. In use, the relevant parameters can be input through dialogue through the man-machine interface, including the main radius, the branch radius, the angle between the two axes, the offset between the two axes, etc., and the cutting process will be completed automatically.
Some parameters such as the cutting speed and the amount of residual height when cutting the peach hole can be freely set during operation. The cantilever type machine can be straddled on the main pipe or cylindrical container, or placed on the platform, and can be cut after being positioned with the attached alignment tool, especially suitable for the circle of 219 660mm The intersecting wire holes are cut on the cylinder.
The machine head and the frame can be easily separated, and the aluminum alloy castings reduce the weight of the machine head, making it easy to use as a functional component. The operator can prepare the corresponding clamping device for various special occasions as needed.
The whole machine is small in size and light in weight, and can be hoisted or lifted up by two people. There are also two lead-off rubber wheels underneath, which can be easily pushed by one person.
When cutting the tube hole, it can be cut into a peach shape at the closing point, leaving it to be manually smoothed to ensure that there is no crater.
4 Advantages of the new CNC cutting process The new CNC cutting technology replaces the drilling machine, the boring machine processing header hole and the header pipe joint groove have the following advantages: high production efficiency. Using CNC cutting machine to cut the intersecting line groove, the cutting speed is 70700mm/min. Take the steel pipe 4133X16 as an example. The length of the intersecting line is 500mm. Cut the intersecting line groove for 1 minute, plus auxiliary clamping. In 2 minutes, a line of cut can be completed in about 3 minutes.
No additional tooling is required. Manual gas cutting intersecting line groove, each type of specification, each angle requires a set of gas cutting master; the upper machine tool processing also needs the corresponding knife row.
Occupy the production site is small. Two stages are required by the traditional process: one station for gas cutting and sanding, and the other for milling and cutting the groove; and with the numerical control gas cutting method, the intersecting line groove can be completed in one station. The processing, and avoiding the troublesome process of lifting the header from one position to another, improves the assembly of the DL-type heat transfer element, and has achieved good results in solving the air preheater clogging. .
Soot blowing and water washing are the main means of cleaning the heating surface of the air preheater. Regular soot blowing and flushing in accordance with the requirements play an active role in preventing the blocked surface of the heated surface. The most common methods are high pressure steam soot and high pressure water rinse. Under normal circumstances, the soot blower is arranged on the flue gas side of the cold end of the heated surface. When the fuel ash is high, the soot blower is arranged at the hot end, and the upper and lower sides are correspondingly purged. High pressure water can be rinsed with clean water or alkaline water. At present, some power plants use explosive devices to solve the problem of ash blocking on the heating surface of air preheaters. Although the equipment used in the heating surface of the air preheater has some short-term effects, there are also many hidden dangers. For example, after a domestic power plant uses hydrogen and oxygen to blast, the heat transfer element piece is shattered, and the broken metal piece is brought to the tail dust collector to block the dust remover. The author believes that: When using such devices, it must be noted that: 1 to distinguish the coal-fired nature of the boiler, it is not suitable for units with a tendency to bond ash. 2 Explosive force does not damage the heat transfer element. 3 Improve the safety of the device on-site use.
4 It is recommended that in the design of air preheater, the manufacturer must fully consider the method of dealing with ash blocking, especially the use of new corrugated heat transfer elements, combined with special high-pressure soot blowing and water washing, so that the boiler is burning more When the coal is ash, the heated surface remains in a good clean state, which greatly prolongs the service life of the components and also stabilizes the air preheater from leaking. Here, in order to prevent ash blocking, the following suggestions are also made for the operation of the air preheater: (1) The soot blowing is properly arranged to ensure that the soot blower can be put into operation as required when the boiler is put into operation. Usually, the ash structure that has just accumulated is loose and easy to blow off, so the soot blower must be put into operation in time.
The coal used in each boiler is different, the amount of ash may vary, and the time and cycle of soot blowing will vary from boiler to boiler. Especially in the start-up phase, in order to reduce the deposition of combustibles and prevent fires, the soot blowers should be continuously put into operation.
The soot blowing media and parameters should meet the requirements. Any moisture component contained in the soot blowing medium can impair its ability to blow air in the air preheater and constitute a potential factor for ash blocking. To prevent condensation of soot blowing steam, ensure steam superheat. The medium pressure is the condition for ensuring penetration, but in order to protect the components, the soot pressure should not be higher than the recommended value, otherwise the component will be torn.
When cleaning the surface, ensure that the cleaning is thorough and clean.
Because the partially uncleaned ash is sintered after re-commissioning, it is more difficult to remove. At the same time, this part of the ash will also block the ash in the upper channel and increase the ash blocking.
(4) Clear the possibility that all water will accumulate on the components. The water flushing pipe and the soot pipe should be completely drained, and the cleaning water of the upper part of the preheater cannot be discharged through the preheater. In addition, the cleaned air preheater rotor It must be blown dry before it can be put into use.
The arrangement of the flue in front of the preheater is unreasonable, which may cause the flue gas corridor generated by the uneven wear of the air preheater, which may cause partial ash blocking and partial severe wear of the heat transfer element. When this phenomenon occurs, a uniform flow of flue gas from the flow guiding device should be installed.
When the fuel is changed, the soot blowing cycle should be modified accordingly. If the original soot blowing equipment cannot meet the requirements of the new fuel, the soot blowing device should be updated or added in time.
Jiang Lifang female. Born in 1954. College graduation. The engineer is currently the design leader of the Air Preheater Company of Shanghai Boiler Works Co., Ltd. Engaged in air preheater design since 1979. Experienced in the design and retrofit of various specifications and models (upper page 23).
5 Conclusion Using CNC cutting new technology instead of drilling machine, boring machine processing box pipe hole and header pipe joint groove is an efficient process, it is worth further promotion.
At present, we are still further exploring and improving, in order to make the CNC cutting machine for the header of the header pipe more perfect and develop Zhu Yaode male to a higher level. Born in 1962. University degree. He is currently the deputy director of the General Manager Office of Shanghai Boiler Factory Co., Ltd. Has long been engaged in technical transformation of the factory.
Yantai Ciso Lubrication Technology Co.,LTD , https://www.cisolubrication.com