Views: 2 Author: Site Editor Publish Time: 2022-01-12 Origin: Site
The paper industry in my country is in a stage of rapid development. With the development of paper machine towards large-scale and high-speed, the original installation method of the base plate with reserved holes and anchor bolts is becoming obsolete, and new installation methods and high-precision measurement methods have become mainstream. . This article focuses on the installation method and installation process of the paper machine foundation board.
The modern paper industry is in the stage of rapid development in our country. In recent years, more and more advanced paper machines have entered our country. The installation accuracy of paper machines is directly related to the operation status and speed of paper machines. The installation of the basic board of the paper machine plays an important role in the installation of the paper machine. If you master the installation of the basic board of the paper machine, you can basically complete the installation of the entire paper machine production line. The production quality and installation accuracy of the base plate directly affect the normal operation of the paper machine. Before installing the foundation board of the paper machine, it is necessary to install and align the anchor bolts, grouting once, then install and align the foundation board, and finally perform the secondary grouting.
Technical requirements for the installation of the base board of the paper machine:
(1) Basic plate processing requirements
At present, most of the basic boards of paper machines are provided by paper machine manufacturers, and the material of the basic boards is HT250. In order to improve the stress deformation and machining accuracy of the base plate, the chemical composition is similar to the following data: ω(C) 3.07%, (Si) 1.36%, ω(Mn) 1.16%, ω(S) 0.07%, ω(p) 0.051 %, ω(Cr) 0.45%, ω(Cu) 0.5%.
Mechanical performance requirements: ab>250MPa at room temperature (25°C). It is required that all 6 planes of the base plate are processed, the upper plane surface finish is 6.3μm, and the flatness is 0.05mm/m; the center line of the foundation (width 0.5 mm and 0.5mm deep inverted triangle), which is convenient for the rough adjustment of the foundation plate. In order to remove the air in the grouting material, the foundation plate should be processed with several exhaust holes. The hole distance tolerance of all anchor bolts is required to be controlled within ±0.5 Within mm; in order to eliminate internal stress, the base plate should be treated by secondary aging.
(2) Installation of foundation plate anchor bolts
At present, there are three main ways to install the foundation plate: the reserved hole installation method, the pre-embedded steel plate installation method, and the pre-embedded anchor bolt installation method.
1. Reserved hole installation method
On some small and medium-sized paper machines and domestic pulp board machines, the installation method of the foundation plate is still using the reserved hole installation method for anchor bolts. The installation of reserved holes means that according to the size of the anchor bolts of the foundation plate of the paper machine, holes are reserved in advance during the civil construction, the foundation plate is placed, and the anchor bolts are inserted through the foundation plate into the holes, and then aligned. Grout the anchor bolts. The reserved bolt hole method is used to install the foundation plate due to the use of reserved holes for civil construction, one grouting after rough adjustment, and then fine adjustment for the last second grouting, so the anchoring strength of anchor bolts is poor. This method has a large installation error, is difficult to correct, and takes a long time to install.
2. Installation method of embedded steel plate
The pre-embedded steel plate installation method is an installation method represented by the German VOITH company. This method is to set the pre-embedded plate at the position of the foundation plate anchor bolts during the construction stage of the foundation beam of the paper machine, and weld the foundation plate anchor bolts during the installation of the foundation plate. on the embedded board. For example, the foundation board of Anhui Jingfeng Paper's 10,000 tons/high-grade cigarette paper machine is installed in this way.
The pre-embedded steel plate is made and corrected to reduce the bending deformation caused by welding. After the reinforcement is laid in the civil construction and the formwork is fixed, it is pre-embedded at the position of the foundation plate anchor bolts.
The installation of the base plate is generally based on the longitudinal centerline of the wire couch roll, and is divided into four groups to advance toward the end of the paper machine. After the foundation plate is first found, the anchor bolts of the foundation plate are spot welded to the embedded plate. After all the anchor bolts are spot welded, lift the foundation plate and complete the anchor bolt welding work. It is required that the welding is firm. After the anchor bolts are fully welded, the foundation plate is hoisted back to its original position for precise searching.
The characteristics of using this method to install the foundation plate: first, the amount of auxiliary steel is small, and there is no cross construction with the civil construction; second, the welding quality of the anchor bolts is high, and the foundation plate needs to be hoisted twice, so the hoisting work is increased; Third, when the base plate is adjusted, the base plate must be aligned one by one without skewing.
3. Pre-embedded anchor bolt installation method
The pre-embedded anchor bolt installation method is the installation method represented by the Finnish MESTO company. The method is to install the anchor bolts of the paper machine foundation board in cooperation with the civil engineering when the paper machine foundation beam is constructed. The plate is installed at the corresponding anchor bolt positions, and the anchor bolts are passed through the bolt holes of the foundation plate. Such as Jingxing 12# paper machine, 450,000 tons/year high-grade kraft box board paper machine base board is installed in this way.
Pre-embedded anchor bolt installation method. Before installation, according to the hole position of the foundation plate, use square steel to weld the simulated foundation plate, and drill holes with the same diameter and hole spacing as the foundation plate at the corresponding position, according to the position of the bolt holes in the foundation plate. , size and number of bolt holes determine the length, size and quantity of the profiles used. Under normal circumstances, the size of the bolt hole is about φ30mm, and the square steel of 50mm-80mm can be used. The length of the profile of the frame is determined by adding 100mm-200mm to the distance between the farthest bolt holes at the longitudinal ends of the base plate, and the length of the profile steel in the frame is determined by the distance between the farthest bolt holes at the lateral ends of the base plate minus the width of the profile, and the number of bolt holes determines the number of profiles . When assembling and welding the simulated base plate, ensure that the upper and lower end surfaces of the simulated base plate are level. Scribe and drill holes on the simulated base plate. When scribing, the dimensional deviation from the center of the bolt hole and the diagonal deviation are controlled within ±0.5mm, and the size deviation of the bolt hole is controlled within ±0.5mm.
The installation of the simulated base plate is a more detailed work, which should be carried out after the reinforcement has been laid in the civil works and the formwork of the foundation girder has been prepared. The simulated foundation slabs are generally made into square steel frame groups, each group of square steel frame groups must be adjusted in the correct spatial position, and should be firmly fixed to avoid displacement due to vibration or bumping when pouring the foundation concrete . The imitation base plate is generally fixed by I-beam or channel steel, and the I-beam or channel steel is fixed on the floor with expansion bolts.
After the simulated base plate is fixed, check the position of the anchor bolts. The position deviation range of the anchor bolts is ±1mm, and the elevation deviation is +5mm; the distance deviation range of two adjacent simulated base plates on the same side is ±1mm; The span deviation of the simulated base plate shall not be greater than 2mm. Hang the anchor bolts on the simulated foundation plate, adjust the elevation of the anchor bolts with a level, and fix the anchor bolts on the simulated foundation plate with two nuts. The anchor bolts are accepted and qualified, and the concrete is poured together with the main beam as a whole. When pouring, the slurry and vibrating rod should not directly hit the anchor bolts and their fixed steel frames, so as to avoid the loose anchor bolts affecting the accuracy.
The characteristics of the installation method of the foundation plate using pre-embedded anchor bolts: first, the amount of auxiliary steel is large, and a large amount of steel is required to make the template and fix the template; second, the accuracy of the anchor bolt pre-embedded stage is high, and the foundation plate installation stage is relatively easy , there is no need to deliberately fine-tune the horizontal and vertical directions of the base plate.
(3) Alignment of the installation of the base plate
After the anchor bolts are installed and aligned and grouted once (the anchor bolts are welded by the method of pre-embedded steel plates), the installation and alignment of the foundation plate can be carried out. After cleaning the foundation plate, lay the foundation plate according to the number, and roughly control the elevation, horizontal, vertical and horizontal position of the foundation plate by means of wire drawing and visual inspection, so as to make the foundation plate as flat as possible. The fine adjustment of the base plate starts from the base plate at the first dryer. Introduce the value of the elevation reference point to the base plate, and adjust the elevation of the rest of the foundation plate based on it, and no longer introduce the elevation value from the elevation reference point. The base plate on the transmission side and the operation side should be finely adjusted in the same direction at the same time. One or two theodolites are erected on the longitudinal centerline of the base plate on the operation side and on the auxiliary installation line to adjust the parallelism of the longitudinal centerline of each base plate. The level can be placed on the floor, and only 6 groups of foundation plates are measured at a time. The last group of foundation plates is used as the first group and the elevation reference for the next level measurement. This method can reduce the accuracy of the level itself. Influence. Control the span level of the foundation board and the longitudinal level of the foundation board surface, and use a level to measure the foundation board. When measuring the longitudinal position of the foundation plate, not only must ensure that the distance error between adjacent foundation plates is within the allowable range, but also check again every certain number of foundation plates.
The parallel error of the foundation plates on both sides is 0.5mm, the span error is 0.5mm, and the elevation error is 0.2mm (the transmission side should not be lower than the operation side). The height difference between the two foundation plates should be controlled within 0.02mm. The level error of the board before installing each column is 0.05mm.
(4) Grouting of base plate
After the foundation plate is finely adjusted, torque the anchor bolts and grouting with non-shrinkage cement. The paper machine foundation board is an ultra-long continuous foundation. Due to the limitation of construction conditions, the construction is carried out by the method of segmented pouring. The grouting should be irrigated from one side, and the other side should overflow the foundation slab. The grouting layer at the bottom must be full and free of voids. Check the compactness of the grouting within two days after grouting (or after the grouting strength reaches 50%): lightly tap the surface of the base plate and listen to the sound of it to determine whether there is a gap. When the grouting layer reaches the design strength, each anchor bolt should be screwed through with a torque wrench according to the specified pre-tightening torque, and the level of the layout should be checked with a level gauge during the tightening process to see if there is any change.
Correct and high-precision installation of the base plate can correct the defects of the paper machine, reduce the vibration of the paper machine to a minimum, and reduce the impact of the paper machine vibration on the stability of the paper web.