I. The foundation of machines and equipment
Machines and equipment must be installed on a solid foundation, if the foundation is not solid, it will affect the operation of the machine and equipment, and even affect the life of the machine or equipment.
The foundation requirements for machinery in motion (called machines) are even more stringent. It is different from the foundation of the equipment (generally referred to in general as non-moving equipment), in addition to static loads in addition to dynamic loads.
Dynamic load is due to the rotating part of the machine and the reciprocating part of the balance of the poor, the dynamic load, the greater the impact on the foundation is also greater. Poorly balanced machines will quickly destroy the foundation (such as ball mills are poorly balanced machines).
As the foundation is subjected to dynamic loads, vibration is generated. In addition to the destructive effect of the machine, vibration is often transmitted through the foundation to neighboring equipment, machines or houses, and make them cracks and premature damage. In addition, the noise nuisance due to vibration will also be transmitted by the poor foundation.
Therefore, in addition to structurally meeting the process requirements, the foundation should be able to transfer the load of machines and equipment to the soil uniformly so that it can absorb the vibration of the machine and isolate the noise. In addition, the foundation should be free from sinking, deflection and overturning after completion, especially during the operation of machines and equipment.
Foundations are built on soil, so before building large foundations, drilling tests of the foundation soil must be carried out to determine the physical properties of the soil and pressure resistance.
Foundations must be designed so that the pressure on the soil does not exceed the allowable pressure resistance of the soil.
The pressure resistance of various soil layers can be seen in Table 10-1.
Foundations should never be built on silty soil, and if they are limited by certain conditions, they can only be reinforced with an artificial sand foundation or pile foundation. Sand foundation is to build the foundation on the artificial compacted sand bedding layer. The thickness and size dimensions of the sand bedding layer must be determined by calculation. Pile foundation is the method of reinforcing the foundation with piles.
Piles are classified as timber piles, reinforced concrete piles, steel piles and sand piles, and their application depends on the nature of the foundation and soil.
Table 10-1 Load Capacity of Various Soil Strata
(I) Structural Types of Foundations
According to the different requirements of machines and equipments for their foundations, their structural types are also different, which can be classified into two main categories: foundations of equipments and foundations of machines.
1. The structural type of equipment foundation
According to the different types of structure, the foundation of the equipment can be divided into single block type and large block type two kinds.
(1) single block type foundation
This foundation is built as a single unit without being connected to other foundations or plant foundations, the general structure of the solid (Figure 10-1 (a), basement type (Figure 10-1 (b)), wall type (Figure 10-1 (c)) and frame type (Figure 10-1 (d)).
Figure 10-1 Structural Types of Foundations
(a) Solid; (b) Basement; (c) Wall; (d) Framed
Solid foundations can be categorized according to the shape of the equipment base into square, rectangular, and circular. They are also available in one-section, multi-section and stepped types.
(2) large block type (plate type) of the foundation
This foundation is built into a continuous large block or plate for the neighboring equipment and auxiliary equipment and piping installation. There is also a pit or hole for management in the foundation. It can also be used as a block foundation with the help of the concrete floor, beams or roof of the plant.
2. Machine foundation structure type
Power machine foundation structure type can also be divided into single block type and large block type, and mainly large block type, especially solid large block type foundation is most widely used. The biggest advantage of this kind of foundation is that it is rigid and has no extended above-ground part. Big block type foundation is built into a continuous big block shape, can according to the main body of the machine and auxiliary equipment work requirements of the building into a suitable shape.
In addition to the block foundation, there are also wall foundations used mainly for mounting rotary machines. As shown in Figure 10-2 for the wall foundation of the motor and turbine blower. Its main load-bearing member is the longitudinal wall on the lower plate of the supporting column.
(B) foundation size calculation
Determine the size of the foundation, must be based on the type of machinery, equipment and stress to consider, can be broadly divided into two categories of static load foundation and power load foundation.
1. static load foundation calculation
Nonmetallic mineral processing production, some equipment is very heavy, so the foundation of these equipment, must be calculated.
General static equipment foundation, are subject to the center of the load, and most of its structure into a stepped pile foundation, in order to save material, as shown in Figure 10-3. Calculate this type of foundation according to the following steps.
Figure 10-2 Wall foundation for electric motor and turbine blower
Figure 10-3 Stepped foundation
(1) The size of the pile is determined by the following formula
Nonmetallic mineral processing machinery and equipment
Formula N - the weight of the equipment and the column itself (kg);
F1 - the cross-sectional area of the column (cm2);
F2 - the total cross-sectional area of the steel reinforcement in the column (cm2);
δ1 - the ultimate strength of concrete (kgf/cm2).
From Table 10-2
δ2--yield limit of reinforcement;
Generic 2500kgf/cm2
K--Safety factor K = 2.2;
F2/F1 - generally between 0.5 and 1%.
Table 10-2
(2) The size of the foundation under the pile can be determined according to the following formula:
Nonmetallic mineral processing machinery and equipment
The formula A - the bottom area of the foundation (cm2);
N- - weight of the equipment and column (kg);
G - weight of the foundation itself (kg);
δ - permissible pressure resistance of the soil (kgf/cm2).
Calculation of the height of the foundation H: for square columns:
Nonmetallic mineral processing machinery and equipment
In the formula H - the minimum height of the foundation (cm);
K1 - the shear when safety factor, K1 = 2.4;
a - side length of the square column (cm);
δ3 - shear ultimate strength of concrete, generally 22kgf/cm2.
For rectangular columns, then :
Nonmetallic mineral processing machinery and equipment
(3) Decision on the number of reinforcement bars in the foundation
The number of reinforcement bars can be derived from the calculation of bending moments. Due to the support pressure of the soil, so that the bending moment occurs within the foundation (foundation as a cantilever beam action), this bending moment in the pile edge to reach its maximum value. Since concrete is a brittle material, the counterbending moment can be regarded as being borne entirely by the steel reinforcement. According to this maximum bending moment on the steel bending stress calculation, you can find the number of bars required.
As shown in Figure 10-4, in section I-I and I′-I′ of the bending moment, is due to the soil has a reaction force on the foundation ABFE and BFGH area caused by the AB side of the bending moment of the force Q1, equal to the trapezoidal area of the ABEF multiplied by the allowable pressure of the soil. The force Q2 of the bending moment on the BH side is equal to the trapezoidal area BFGH multiplied by the permissible pressure resistance of the soil. That is:
Nonmetallic mineral processing machinery and equipment
If a square foundation or square column, then:
Nonmetallic mineral processing machinery and equipment
Bending moment at I-I section:
M1 = Q1L1
Figure 10-4 Calculation of foundation reinforcement
In the formula L1 --the distance from the center of gravity of trapezoidal ABEF to section I-I
Nonmetallic mineral processing machinery and equipment
Bending moment at section I′-I′
M2 = Q2L2
Eq.
If square foundation and square columns are used, then
M1 = M2
So the number of bars in both directions is also equal. Soil pressure produces bending moments at section I-I and I′-I′. In order not to cause damage to the foundation by bending, must produce an internal bending moment to resist the generation of this moment, thus getting the following equilibrium of the bending moment:
Non-metallic mineral processing machinery and equipment
In M - bending moment (kgf-cm);
F2 --Total cross-sectional area of reinforcement in the column (cm2);
K --Safety coefficient;
L --Arm of bending moment (effective height of the foundation), can be taken as 0.875H (cm).
After the total area of the reinforcement is found, a suitable diameter of reinforcement is selected and its number can be decided.
2. Calculation of power load foundation
Calculation of the foundation of a power machine is a more complicated work, which is not intended to be described theoretically because of the consideration of disturbing vibration. A simple method of determining the foundation for power loads is described below.
The two dimensions of the length and width of the foundation can be added by the length and width of the base of the machine 150 to 250mm, while the height of the foundation can be calculated according to the following methods:
(1) Determination of the weight of the foundation
G = a-Q
In the formula a - the load factor of the foundation
Q - the weight of the machine (kg);
G - the weight of the foundation (kg).
①For horizontal piston type machine it can be taken:
Piston speed (m/s) v=1,2,3,4
Load coefficient a=2,2.5,3.5,4.5;
②For vertical piston type machine, the coefficient is reduced by about 35% accordingly;
③For motors with no braking and running, the coefficient a=10 is taken;
For a braked and often reversed, and the load is not stable motor, take the coefficient a = 20;
4 for other rotating machines (pumps and ventilators), in determining the depth of the foundation, you can take the coefficient a = 10.
(2) the foundation of the volume of the determination of the
Knowing the weight of the foundation, according to the following formula to find the volume of:
V = G/q (m3)
In the formula q - the weight of the foundation of one cubic meter, for the brick foundation, take q = 1800kg/m3; for the concrete foundation, take q = 2000kg/m3.
(3) Determination of the size of the foundation
First of all, according to the machine frame Dimensions to determine the length and width of the foundation, and then find the height of the foundation:
Nonmetallic mineral processing machinery and equipment
In the formula A and B - the length and width of the foundation, which depends on the length and width of the rack.
The calculated height of the foundation should be greater than the depth of the frozen layer at that time. The foundation should be 150-300mm above the floor to avoid water splashing on the machine when the floor is cleaned.
(C) Construction of the foundation
Construction of the foundation includes such processes as digging the earth, laying the foundation floor, nailing the cross board, laying the reinforcing steel, placing the ground bolts, pouring the concrete and maintaining it.
Excavation is on the ground of foundation construction, according to the shape of the foundation dug out the corresponding size and depth of the pit.
Doing the foundation subgrade is to build the subgrade of the foundation by masonry between the foundation and the soil according to the nature of the foundation soil. If the foundation is built on soil that can withstand a large load, such as large hard rock, gravel, or sandstone soils, the foundation for the building's foundation must only be shoveled. If the soil is soft, it is necessary to make a layer of concrete foundation substrate, the thickness of which is 300 ~ 7500mm. if you do not build artificial hard foundation substrate, the loose soil will release or absorb moisture, then the foundation shrinks or expands, so that the foundation to produce cracks cause damage to the entire structure and accidents occur.
If the soil is very soft, it must be reinforced with piles. The diameter and length of the pile and the distance between the pile and the pile are determined according to the soil quality and load size.
After the subgrade has been driven, formwork is nailed around the perimeter of the foundation. The formwork should be nailed solidly to avoid deformation during the hydration reaction of concrete cement.
Pouring concrete is an important process of foundation construction. The proportion of concrete, must be strictly according to the provisions of the design.
See Table 10-3 for the use of different grades of concrete.
Table 10-3 Concrete grades used in various foundation projects
Inside the concrete foundation, if the holes for the footbolts are set aside in advance, before pouring the hole should be placed in the location of the reserved holes after planing of the square stake, the size and length of the square stake should be determined according to the dimensions of the footbolts. In order that the stakes may be easily removed after the concrete has set, they are made to have a sloping shape and felt or felt paper is wrapped around them. It is best to gently rock the stake a few times before the foundation is fully set so that the concrete is not firmly bonded to the stake for easy removal later.
(D) Ground Bolts
All machines and equipment are connected to the foundation by ground bolts. There are several shapes of ground bolts, as shown in Figure 10-5. The diameter of the foot bolt in 24mm or less, the lower end of its bent as in Figure 10-5 (a), (b), (d) three kinds of shapes; diameter in the range of 25 ~ 50mm in the foot bolt can be taken as in Figure 10-5 (c), (e), (f) and so on the shape of the diameter of more than 50mm in the foot bolt is used in the shape of (g), (h), (i) and so on.
When pouring the foundation, if the footbolt is poured dead inside the foundation, there are usually two methods: one is when pouring the foundation, leave the footbolt holes on the foundation, and then put on the bolts after installing the machine, and then use the cement slurry to pour the footbolt dead; a kind is before pouring the foundation, the position of the footbolt is fixed with the fixing bracket, and when pouring the foundation, pour the footbolt in the concrete at one time. The former is called the secondary pouring method. The former is called the second pouring method, the latter is called a pouring method. One pouring method can reduce the nail template project, increase the stability and solidity of the footbolt, so as to improve the seismic performance of the footbolt. Therefore, the one-time pouring method is an advanced method.
Figure 10-5 Shape of footbolt
General machinery and equipment, such as pumps, ventilators, etc., if the one-time pouring method is used, after fixing the footbolt with the fixing bracket, the centerline, perpendicularity and elevation of the footbolt should be strictly checked before pouring the concrete. Its allowable centerline deviation is limited to ±4~5mm, elevation deviation is limited to ±10mm, verticality deviation shall not exceed 1% slope.
(E) Deviation treatment of footing bolts
When pouring the foundation, great importance should be attached to the position, elevation and quality of the footing bolts poured in accordance with the technical specifications. If the position of the bolt due to design changes or inadmissible deviation, it will affect the installation, must try to deal with. The following describes the centerline and elevation deviation of the foot bolt and live extraction processing methods.
1. Centerline deviation of the treatment
To be dealt with around the bolt with a steel chisel chisel away from the concrete around the bolt, keep for (8 ~ 15) d, with an acetylene flame heated bolts to the cherry red (850 ℃ or so), pay attention to the temperature can not be too high, so as not to cause changes in the organization of the metal and reduce the strength of the bolt, heated bolts with a jack or sledgehammer corrected, and in the bent place! Welded steel plate to prevent future straightening, as shown in Figure 10-6.
Figure 10-6 center line deviation treatment
2. Deviation treatment of elevation
Bolt is too high can be cut off the excessive length of the part, and re-processing of the thread. Bolt is too low, the general processing method is to use acetylene flame to bake the bolt red elongation. After elongation in the diameter of the reduced part of the sides of the welded steel or with the appropriate size of the steel pipe for welding (as shown in Figure 10-7 (a) (b)). If too much lower, baked red elongation does not help, can be in the unqualified bolts on the top end of the re-welded on a section of the same specifications of the bolt (as shown in Figure 10-7 (c)), in the weld must be welded again with reinforcing bars.
3. Bolts live pulled out of the treatment
Sometimes too much force, may be pulled loose from the foundation of the ground bolts, the remedy can be a part of the foundation of the bolt waist chiseled away, and in the bolts welded on the two intersecting rebar (as shown in Figure 10-8), and then fill in the concrete, can be active bolts solid. About the treatment method can be dealt with according to the actual situation.
Figure 10-7 Elevation deviation treatment
Figure 10-8 Treatment of bolt pulling out
(F) Technical requirements for foundation of machinery and equipment
When there is a lack of foundation drawings of machinery and equipment, we can refer to the above procedure to organize construction. If some machines or equipments are attached with foundation drawings, they should be constructed according to the drawings. The foundation is used to fix the equipment, before the equipment installation, according to the foundation drawings and installation drawings against the equipment base foot bolt hole location, check the size and quality. Specific technical requirements are as follows:
(1) the center of the foundation position size, should be consistent with the design size of the construction drawings, the error should not exceed 20mm.
(2) the plane contour size of the foundation, should be larger than the equipment base contour size, generally required to be larger than the base contour size of more than 100mm.
(3) the center of gravity of the foundation and the center of gravity of the equipment should be in the same vertical plane, the error is not more than 10 ~ 15mm, so as to avoid tilt and sinking.
(4) After the foundation reaches the maintenance period, there shall be no loose, cracks, honeycomb, pockmarked surface and exposed tendons. When checking with a small hammer, the sound should be solid, there should be no damage peeling.
(5) the foundation of the reserved foot bolt holes, its hole template should be cleaned up, there shall be no debris in the hole (wood, brick, rags, etc.).
(6) The center position deviation of the foot bolt fixed in the foundation in one pour should not be more than ±2~3mm.
(7) The center deviation of the reserved foot bolt holes should not be more than 10mm, and the perpendicularity of the holes should not be more than Sh10~15mm per meter.
(8) The strength of the foundation must be more than 75% before the installation of the equipment can be set in place.
(8) Before the equipment installation, the foundation strength must be 75% or more before the equipment can be put in place.
Second, the installation of machinery and equipment
The above preparatory work has been done, the equipment arrived at the site, the installation work can be carried out.
Equipment installation should be carried out according to the order of the first host after auxiliary machines, the first large surface after the small surface, the first long line after the short line. Installation of the first step is the lifting of machinery and equipment, lifting should be carefully checked before the lifting device and equipment bundling, check fully qualified before lifting. Lifting work should be carried out under unified command. When the equipment is lifted to the foundation above the position slightly above the ground bolt, you can carry out the equipment in place. Equipment in place is to make the equipment base on the ground bolt holes aligned with the foundation of the ground bolt or reserved holes, the equipment will be placed on the foundation surface of the pad. After the equipment is in place, before the lifting device is removed, the second step of the installation should be carried out - the calibration of the equipment. Calibration work includes finding the right and leveling two. Finding is to ensure that the horizontal position and elevation of the centerline of the equipment meets the design requirements. Leveling is to achieve the level of equipment, parallelism and mutual verticality requirements, so that the equipment can work properly after installation. Equipment installation correction work, must be in accordance with the construction drawings, equipment specifications and technical procedures for the provisions of the installation, such as deviation, such deviation shall not exceed the prescribed allowable range, otherwise the installation will be considered unqualified. After equipment calibration, the second grouting can be carried out. Before grouting, the reserved holes for ground bolts should be cleaned and the surface of the foundation should be scrubbed. After the cement mortar of the secondary grouting has set and hardened, another calibration check will be made while tightening the foot bolts.
Trial run (test run) is the final stage in the installation project. After trial run, mechanical equipment can be formally put into production in accordance with the design requirements. In the test run, due to mechanical equipment in the design and installation, assembly and adjustment of all the defects will be manifested, the problem is often complex and multifaceted, therefore, in the test run before, not only to make a detailed inspection of machinery and equipment, reasonably equipped with mechanics, and the relevant professionals should be present, but also a staff familiar with the performance of this type of equipment for the test run of the command. Various mechanical equipment test run requirements are different, generally speaking, the basic requirements are as follows:
1. In the test run to understand the performance of the machine and its mechanism of good and bad, and to confirm the quality of the installation to meet the specified requirements, so that machinery and equipment can be successfully put into production.
2. The operator should be familiar with the performance of the machine through the test run, so that it can master the correct operation method in production.
3. Through the test run in time to find the defects of the machine, in order to put into production before the early repair and adjustment.
After the trial run is considered qualified, the installation department can be formally transferred to the production sector into use.