Application introduction of the hottest concrete p

Introduction to the use of concrete pump

1, concrete pump selection

1.1 classification

from the mobility, it can be divided into automobile concrete pump (car pump), frame pump (without movable boom), and towed concrete pump. From the power form, it can be divided into electric type and internal combustion engine type. In terms of pumping form, at present, inclined gate valve and "s" pipe valve are widely used in China; The advantage of the former is that the aggregate diameter in the concrete is required to be wide (40mm), and the price is low. The disadvantage is that the gate valve needs continuous lubrication, and the pumping height is about 100m; The latter has no lubrication system to confirm that the aging aggregate adhered by the tape has strict requirements (no more than 33mm), the pumping height can reach more than 150m, and the price is generally high

1.2 type selection

according to work experience, in the construction of large thermal power plants, concrete equipment is generally equipped with two mixing plants (stations), three concrete pumps, one pump truck two Trailer pumps or two pump trucks one trailer pumps, and most of them choose inclined gate valve type to meet the aggregate requirements, so the mobility, economy and practicality are more reasonable

1.3 precautions for model selection

(1) when selecting a concrete pump, you must first visit the user to understand the actual use in detail

(2) concrete pumps produced in batches by regular manufacturers must be selected

(3) try not to select the first (first batch) concrete pump produced by any manufacturer

(4) sign a contract directly with the Sales Office of the manufacturer to purchase, and try not to go through intermediate links, so as to facilitate maintenance services

2. New pump commissioning

2.1 commissioning content before receiving the pump in the manufacturer

(1) personnel composition: 1 technician, 1 operator, 1 driver, and the operator is a skilled worker

(2) read the instructions carefully

(3) check whether the concrete pump is consistent with the model in the contract, and whether the certificate number is consistent with the nameplate number

(4) whether the appearance is satisfactory and whether there is oil leakage

(5) operate according to the instructions and measure the movement times of the conveying piston at the maximum and minimum displacement. For example, the minimum displacement of HBT60 pump of Hubei construction machinery factory is 8 ± 1 times/minute, and the maximum displacement is 28 ± 1 times/minute

(6) check whether the mixing system, cooling system and lubrication system are normal, and whether the boom system, outrigger system and automobile part of the automobile boom pump are normal

(7) operate without load for 2h, recheck whether there is oil leakage and seepage in each system, and all pressure gauges should be normal during this period

(8) check whether all accompanying spare parts are complete and intact

it can be accepted only after all are qualified

2.2 commissioning content before the first use on the site

(1) repeat the manufacturer's commissioning content of connecting the pump

(2) the concrete pump placement site should be flat and solid, especially at the support of outriggers. The concrete pump shall be as close to the construction point as possible, and the exit route after the operation shall be considered

(3) arrange and reinforce the transmission pipeline (external connecting pipe)

(4) operate at no-load for 10 ~ 20min, so that grease appears obviously at all lubrication points

(5) pump 1 ~ 2m3 mortar with medium displacement. When the mortar is almost finished, pour the concrete and directly turn to normal pumping

during pump test, carefully observe whether each part works normally. If the oil pump, oil temperature and main pressure gauge change, the frame pump should also pay attention to the action of the boom and the working condition of the engine. If there is any abnormal condition, it should be shut down immediately, find out the cause, eliminate the fault and retest. Do not wash the pump after pumping, carefully check whether there is oil leakage and seepage in each part, and wash the pump or put it into use directly after it is qualified

3. Pumping skills

the difficulty of concrete pumping (i.e. pumping effect) generally depends on the quality of concrete itself, the distance between pouring points, the size of delivery pipes, the pipe layout, and the timely elimination of pipe blockage and sudden pipe blockage. (the quality of concrete itself has a great impact on the concrete pumping effect, but it is not introduced here)

3.1 selection of conveying pipe

select the appropriate conveying pipe according to table 1 comparison table of the maximum particle size of concrete coarse aggregate

3.2 the arrangement of external connecting pipes

elbows should be minimized, and seriously worn pipes should be arranged as far away from the concrete pump as possible to avoid pipe explosion due to high pressure

various forms of pipe laying are converted to horizontal length (approximate)

3.3 elimination of concrete pump pipe blockage

(1) reverse pump elimination once the pipe is blocked, press the "reverse pump" switch, and generally the reverse pump can be eliminated after running for 4 ~ 5 strokes

(2) when the pipe blockage cannot be eliminated during reverse pump operation, disassemble the delivery pipe at the blockage as soon as possible and remove the blockage. Note that in addition to cutting off the power, the residual pressure in the pipe must be completely eliminated before removing the pipe

3.4 seasonal construction cannot reflect the real situation of the measuring system of the experimental machine.

for construction in hot weather in summer, wet cover cloth, straw bags, etc. should be used to cover the conveying pipe, so as to avoid causing "dehydration" of concrete in the pipe and difficult transportation. During construction in winter, it is advisable to wrap the conveying pipe with thermal insulation materials to prevent the concrete in the pipe from freezing

3.5 precautions after pumping operation

(1) thoroughly clean the concrete pump and external connecting pipe

(2) check and pack the random tools

(3) idle for 20min to fill all lubricating points with grease

(4) safely leave the operation site

4. Daily maintenance

as there are many types of concrete pumps, here are only some general maintenance

4.1 inspection items before departure

(1) boom, slide valve and outrigger should be fully retracted and locked

(2) work lights and signal devices work normally

(3) there is sufficient fuel, grease and washing water

(4) the hydraulic oil is sufficient and there is no oil leakage at all parts

(5) all kinds of piping, tools, appliances and accessories should be complete

4.2 inspection cycle of main components

(1) daily inspect the appearance for damage and deformation, loosening of exposed components, changes in operation and performance, oil leakage, hose damage, lack of lubricating grease at lubricating points, and unsafe driving factors

(2) monthly (or 2000m3 of pump concrete) quick inspection of slide valve damage, transmission pipe wear, hydraulic oil reduction, forced lubrication of lubrication points, and routine maintenance of automobile parts

(3) half a year (or 12000m3 of pump concrete) check the lower shell of slide valve and delivery cylinder for damage, electrical components, hydraulic oil deterioration, boom damage, and routine maintenance of automobile parts

(4) check the mixing device, mixing oil motor, rotary oil motor, water pump and each oil pump every year (or 24000m3 of pump concrete), and replace the hydraulic oil

(5) check all items every two years (or 48000m3 of pump concrete). Pay attention to the replacement of all seals during disassembly and inspection. The automobile part should be overhauled at the designated or professional repair point

4.3 selection of hydraulic oil, lubricating oil and grease

hydraulic oil model: Winter 32 anti-wear hydraulic oil, non winter 46 anti-wear hydraulic oil

slide valve lubrication: non extreme pressure No. 000 lithium base grease is used in winter, and non extreme pressure No. 00 lithium base grease is unswervingly used by domestic and international well-known alloy manufacturers

lubrication of automobile and other parts: calcium base grease No. 2 or refer to the instruction manual

5. Repair of vulnerable parts

5.1 repair scope

in the chuck slide valve concrete pump, there are many parts in contact with the concrete, and the wear is very serious, but what we can repair is limited to individual parts, and the rest, such as rubber parts, concrete delivery cylinders, slide valve rods and other parts, are fine processed, and generally replaced. Repairable wear parts are divided into two categories: one is surfacing repair parts, such as slide valve plate, slide valve bottom cover (also known as slide valve lower shell), slide valve upper and lower valve seats, and mixing blades; The other is welding repair, mainly concrete delivery pipe

5.2 detect the wear condition

generally, the lower part of the slide valve plate is seriously worn. When the difference between the size of the new part and the size after wear is greater than 5mm, it needs to be repaired; The middle part of the upper and lower valve seats of the slide valve is seriously worn. When the difference between the size of the new part and the wear size is greater than 4mm, it needs to be repaired; The corners on both sides of the mixing blade are seriously worn. When the difference between the size of the new part and the size after wear is greater than 8mm, it needs to be repaired; The lower and both sides of the slide valve bottom cover are seriously worn. When the size difference between the new part and the worn one is greater than 5mm, it needs to be repaired

5.3 repair process

(1) determine the chemical composition test results of the material slide valve bottom cover, c:3.13%, si:2.06%, mn:0.83%, p:0.102%, s:0.126%; The hardness is hb203 ~ 228; It can be determined that the material is MT-4 wear-resistant cast iron

(2) welding rod selection: Austenitic nickel base welding rods Ao 102 and AO 302 with good thermal cracking resistance shall be selected for bottom surfacing. In order to further improve the wear resistance of the surfacing part, on the premise of ensuring that the base metal does not crack, cemented carbide electrode pile 667 and pile 507 should be used for surfacing on the surface of the surfacing layer

(3) before the surfacing method is used, the Ao 102 and AO 302 electrodes are dried at 105 ℃ ~ 200 ℃ for 1h, and the stack 667 and stack 507 electrodes are dried at 300 ℃ ~ 450 ℃ for 2h, so as to reduce the hydrogen content in the welding silkworm and prevent pores. AC welding machines are used for both kinds of welding rods. The former has a current of 100 ~ 110A and the latter has a current of 130 ~ 140A

remove the oil dirt, concrete and other impurities on the surface of the surfacing part, and grind the incomplete fatigue layer with a flexible shaft grinding wheel to expose the metal luster on the surface. Wrap the cylinder barrel and surrounding parts with asbestos or cotton cloth to prevent burns during surfacing. Preheat the bottom cover to 150 ℃ ~ 250 ℃ to prevent cracks. The moving direction of welding rod during surfacing adopts the straight-line feeding method. The welding sequence adopts the segmented back welding method, which retreats from the inside to the outside, but the direction of electrode movement is from the outside to the inside. The surfacing length of each section shall not be greater than 50mm, and the influence of welding heat shall be avoided as far as possible. After welding each section, carefully knock with sharpened reinforcement to eliminate residual stress and prevent cracks. After welding, wrap it with asbestos immediately to make it cool slowly. After cooling, grind and process the surfacing surface with a grinder. After grinding, check with coloring method to confirm that there is no crack more than 30mm. Note that pile 667 or pile 507 can only have one layer of surfacing surface

except for the delivery pipe, other easily worn parts can be repaired according to the repair method of the slide valve bottom cover, and the steps can be simplified

(4) there are four situations for repairing the conveying pipe, which are briefly introduced as follows:

① if the conveying pipe is crushed, first make a simple fixture, which can also be replaced by a vice. Then prepare a steel pipe with an outer diameter close to (slightly less than) the inner diameter of the conveying pipe, and one end of the steel pipe is treated into a bullet head shape. In this way, only heat the crushed part and correct the circle with the steel pipe

② local wear through generally only repair the elbow, because under normal circumstances, when a part of the straight pipe is worn through, the rest of the parts are close to the wear limit and have no repair value, while the elbow is generally worn out first. The repair method is to cut a piece of material with moderate size on the waste pipe, grind the damaged parts and pieces with a grinder, and select the welding rod suitable for the pipe for welding. Pay attention to the curvature of the repaired part

③ if the pipe hoop falls off, the part with the pipe hoop can be cut off from the waste pipe. The length of the conveying pipe with the pipe hoop should be 45 ~ 55mm. Grind the welding part with a grinder and select a suitable electrode for welding

④ if the straight (curved) pipe with wear limit hole leaks slurry in the hole, it is generally no longer repaired and used. If it needs to be repaired and used, the tail of the external connecting pipe with low pressure can be used. In fact, generally, the repaired delivery pipe is best used at the tail of the external connecting pipe, and it is forbidden to use it on the boom

6. How to prolong the service life of slide valves

there are 7 inclined concrete transfer pumps. In the process of use, the problem of premature failure of slide valves is often encountered, mainly as follows: