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During the drilling process of long spiral drilling rig, attention should be paid to the verticality of drilling, and the main technical measures for controlling the verticality of drilling are:
(1) Compact and level the construction site.
(2) When installing the drilling rig, the flatness of the drilling and the verticality of the active drill pipe should be strictly checked. The verticality of the active drill pipe should be regularly checked during the drilling process, and the deviation should be immediately adjusted.
(3) Regularly check the drill, drill pipe, drill pipe joints, find problems and repair or replace them in time.
(4) Drilling at the interface of soft and hard soil or at the inclined rock face should be done at low speed and low pressure. Found that drilling deviation, should be timely backfill clay, and then low-level drilling and low pressure drilling.
(5) Drilling in complex formations, if necessary, add a grooving machine on the drill pipe.
Underwater perfusion process should pay attention to:
1 When using high-grade cement for preparation, attention should be paid to the relationship between the initial setting and final setting time of the concrete and the perfusion time of the single pile. If necessary, add the antimony retarder. The construction site should strictly control the mix ratio (especially water-cement ratio) and mixing time. To master the workability and slump of slugs, prevent the segregation and plugging of the sputum during the infusion process.
2 Depth of buried pipe at the time of initial irrigation
China's JGJ94-94 specification stipulates that the distance from the bottom of the perfusion catheter to the bottom of the hole should be 300-500mm, and the initial depth of the catheter should be ≥800mm. When calculating the initial volume of concrete, individual construction units only calculated the amount of plutonium needed for a 1.3m pile length, and calculated the amount of plutonium accumulated in the pipe. The lack of initial filling caused the depth of the buried pipe to fall below the specified value. On the other hand, the length of the pipe length prepared by the construction unit is too small, the pipe is difficult to install when installing the pipe, and sometimes the distance between the pipe and the bottom of the hole is too large, and the pipe installer does not inform the piling class of the actual distance in time, resulting in insufficient initial filling capacity. The depth of the buried pipe did not reach the specified value. The amount of initial irrigation volume V should be calculated according to the design of pile diameter, diameter of the conduit, installation length of the conduit, and mud density in the hole, and V≥V0+V1. V0 is the length of the pile of 1.3m long, V0=1.2×1.3Ï€D2/4 (unit: m3); 1.2—the theoretical filling factor of the pile; D—the designed pile diameter (m). V1 is the amount of helium accumulated in the catheter at the time of initial irrigation, V1=(hÏ€d2/4)(Ï+0.55Ï€d)/2.4 (unit: m3); h—the length of the catheter installation (m); d—the diameter of the catheter (m) ; Ï - mud density in the hole (t/m3); 0.55 - coefficient of friction of the inner wall of the conduit; 2.4 - density of helium (t/m3).
3 blocked tube during infusion
Intubation occurs when the blockage occurs mainly due to leakage of the perfusion catheter, the depth of the perforation of the catheter at the bottom of the hole is too small, the preparation time for infusing the fistula after completing the secondary clearance is too long, the septum is not standardized, the quality of the osmium preparation is poor, and the perfusion process Infusing catheter is too deep and other reasons.
The perfusion catheter should be inspected by the person in charge prior to installation. The inspection can be performed by a combination of naked eye observation and tapping. The inspection items are mainly whether the perfusion catheter has small holes and cracks, whether the joint of the perfusion catheter is sealed, and the thickness of the perfusion catheter. Eligibility. If necessary, use the test assembly pressure water method to check whether the catheter is leaking. The distance from the bottom of the infusion tube to the bottom of the hole should be 300-500mm. If the initial filling volume of the grouting equipment is sufficient, it should be as large as possible. The sluice should be carefully and carefully manufactured, its diameter and garden should meet the requirements of use, and its length should be ≤ 200mm.
After the completion of the second clearing, the infusion should be started immediately. If the infusion is delayed for some reason, the clearing should be performed again. Otherwise, sand particles suspended in the pores may sink and the bottom sediment may be too thick, which may lead to the occurrence of plugging accidents due to the fact that the hydrants cannot escape the conduit.
4 Rebar cage floats during filling process
There are three main reasons for the rise of reinforcement cage during the infusion process:
(1) The initial setting time and the final setting time of the concrete are too short, so that the inside of the hole will be agglomeration prematurely. When the surface of the concrete rises to the bottom of the reinforcement cage, the concrete will hold up the reinforcement cage.
(2) There are too many sand particles suspended in pores during cleaning, and the sand particles sink back to the surface during the perfusion process to form a denser sand layer and gradually increase with the internal porosity. When the sand layer rises to the reinforcement cage Hold the reinforcement cage at the bottom.
(3) When the concrete is poured into the bottom of the reinforcement cage, the perfusion rate is too fast, causing the reinforcement cage to float.
In the event of a reinforcement cage floating up, the cause should be immediately identified and appropriate measures taken to prevent recurrence.
5 Low strength or enthalpy of piles
It was found that the main reasons for the low strength of concrete piles or the segregation of concrete piles in Henan Sanli Machinery were the poor control of concrete mix ratio at the construction site, insufficient mixing time, and poor cement quality. Strictly controlling the quality of the incoming cement, controlling the mixing ratio at the construction site, and mastering the mixing time and workability of the concrete, is an effective measure to prevent pile separation and low strength.
6 Pile slag or broken pile
There are four main reasons for causing piles, mud, or broken piles:
(1) The amount of irrigation at the beginning is not enough, resulting in the depth of the buried tube after the initial irrigation is too small or the catheter is not inserted into the fistula at all.
(2) The length of the extubation was not controlled during the perfusion, and the catheter was pulled out.
(3) The initial coagulation time and final coagulation time are too short, or the filling time is too long, causing the upper part of the bowl to agglomerate, causing slag inclusion in the pile body.
(4) There are too many sand particles suspended in the hole during cleaning, and the sand sinks back to the surface during the perfusion process, forming a sedimentary sand layer and impeding the normal rise of the earthworm. When the earthworm breaks through the sedimentary sand layer, part of the sand and floats The slag is packed into the pot. In severe cases, it may cause a pipe plugging accident, resulting in disrupted perfusion.
The depth of the buried pipe of the pipe should be controlled between 2 and 6 meters. If the pouring is successful and the mud returns from the hole, the depth of the pipe can be appropriately increased to increase the filling speed and shorten the time of pouring the single pile.拔 Infuse the extubation process should be specially responsible for directing, and use the theoretical amount of filling into the hole to calculate the hole surface and the weight of the hole inside the measured surface, take the low value of the two to control the extubation length, to ensure the depth of the buried pipe ≥ 2 meters. Single piles should be controlled at 1.5 times the initial setting time.
7 The top of the pile is not dense or the strength cannot meet the design requirements. The main reason is that the height of the overfilling is not enough.
For piles with a pile diameter ≤ 1000 mm, the height of the overburden is not less than 4% of the pile length. For piles with a pile diameter of >1000mm, the overfilling height is not less than 5% of the pile length. For large piles of concrete piles, the mix within 10 meters of the top of the pile should be properly adjusted to increase the content of gravel and reduce the top of the pile. In the final stage of perfusion, the determination of the surface in the hole shall be determined by a hard-barrel sampling method.
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Tungsten carbide roller has characteristics of good wear resistance, high temperature red hardness, thermal fatigue resistance and thermal conductivity and high strength , have been widely used in high-speed wire rod, bar, rebar, seamless steel tubes, etc. Domestic production of tungsten carbide roller materials mostly WC- Co, WC- Co- Ni- Cr two series, and the content of Co, Co- Ni - Cr is in the range of 6wt% ~ 30wt%. From the use of perspective, tungsten carbide rollers has good mechanical properties, its flexural strength up to 2200 MPa or more, shock toughness up (4 ~ 6) × 10^6 J/ m^2, Rockwell hardness (HRA) is up to 78 to 90, widely in the high-speed wire rod rolling process, which is much higher than single-slot chilled cast steel or high speed steel rolls.Tungsten carbide is made of Tungsten Carbide Powder and binder phase (such as drilling, nickel, etc.), and then pressing and sintering, regardless of the conditions under cold rolled or hot rolled has excellent wear resistance, tungsten carbide rollers has been widely used in pre-finishing mill and finishing of high-speed wire rod currently. On the performance of tungsten carbide roller in hot-rolling wire rod , the material must meet the following requirements:
1. Sufficient anti-fracture strength;
2. Good abrasion resistance;
3. The smooth surface finish;
4. Excellent corrosion resistance, thermal fatigue, thermal cracking performance.
Tungsten carbide roller rings can working in bad conditions , small profile rolling (especially rebar rolling) process conditions is harsher than the high-speed wire rod, and therefore corresponds to the profile rolling ,tungsten carbide rollers recommend using high binder phase carbide.
Tungsten carbide roller material design
Pre-finishing all vehicles roller should ensure its high toughness, strength, rigidity and thermal conductivity, followed before considering its wear resistance. When designing each vehicles roller, pre-finishing materials should choose carbide grades of Co, Co- Ni- Cr binder content is high (greater than or equal to 25wt%) , requiring an average WC grain size of coarse (5μm ~ 6μm), to obtain a higher shock toughness, proper strength and hardness. For the finishing of the roller movements, particularly the last two rollers of the finish rolling, which suffered load is small, and high relative velocity of the material to be pressed (80 m / min ~ 120 m / min). In this case, the wear resistance of the roller to be the most important requirements, and must ensure the strength , timpact toughness and hardness of a reasonable match, so the binder of Co / Ni content ratio and the average grain WC control of particle size and other factors must have greater control in front of different pre-finishing rolling roll.
Tungsten carbide roller category
According to the structure of tungsten carbide rollers, it can be divided into solid tungsten carbide roller and composite tungsten carbide roller. Solid tungsten carbide rollers have been widely used in pre-finishing and finishing stands high speed wire rod mill (including fixed reducing the rack, pinch roller rack). Composite tungsten carbide roller is made of cemented carbide and other materials, and it can be divided into tungsten carbide composite roll rings and solid tungsten carbide composite roller. Tungsten carbide composite roll rings mounted on the roller shaft; solid tungsten carbide composite roller will be directly cast in the roll axis to form a whole, a large load is applied to the rolling mill.
Tungsten carbide roller production process control
Tungsten carbide rollers produced by powder metallurgy method, the key to its process control is the chemical composition of the material and the mixture was prepared, pressed molding, sintering and deep processing and other preparation process parameters.
1. Preparation of starting material (WC focus quality): As the WC raw material and quality control of the use of different levels of quality may fluctuate, resulting in adverse effects on microstructure.
2. Preparation of the mixture: Mixture preparation is the key to the production process of the roller, the roller of failure modes - trachoma, mainly generated by this procedure.
3. Pressing: roller pressing is an important process of the roller mill.
4. Sintering: roller sintering is to determine the final quality of the roller production processes, use of advanced low-pressure sintering technology, HIP sintering technology can greatly improve the performance of roller.
5. Deep processing: deep processing rollers have a greater impact on the quality and accuracy of the roller surface.
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