What Is a Posture Pump?

With the rise of modern industry, the construction method that uses concrete as the main material has become one of the main structures in the construction industry, occupying a large proportion in various engineering constructions, making the development of concrete machinery enduring. And there is a growing situation. Tow concrete pump, referred to as tow pump, is one of various concrete machinery used for conveying and pouring work in concrete construction.

Towing pump

With the rise of modern industry, the construction method that uses concrete as the main material has become one of the main structures in the construction industry, occupying a large proportion in various engineering constructions, making the development of concrete machinery enduring. And there is a growing situation. Tow concrete pump, referred to as tow pump, is one of various concrete machinery used for conveying and pouring work in concrete construction.

Chinese name

Towing pump

Technical Parameters

Displacement and outlet pressure

Concept

Trailer concrete pump

main products

Three-stage concrete pump

Generally, a concrete pump has the following main technical parameters: delivery displacement, outlet pressure, power and distribution valve form. According to the new national standard, these several main parameters can be known from the concrete pump model.

1. Meaning of model parameter of gate valve drag pump:

a. For example, HBT30-45Z, HBTrepresents a towed concrete pump; 30represents a maximum theoretical volume per hour of 30 cubic meters; 45represents a motor power of 45 kilowatts; Zrepresents a gate valve pump; IIIrepresents Third generation products .

b. For example, HBT70C and HBT60D, Crepresents electric pump; Drepresents diesel pump .

2. The meaning of S valve tow pump model parameters:

For example, HBT80.13-130RS, HBTrepresents a towed concrete pump; 80represents a maximum theoretical volume of 80 cubic meters per hour; 13represents an outlet pressure of 13 MPa; 130represents a diesel engine with a power of 130 kW; R Represents diesel power; Srepresents S valve pump .

3. Model meaning of butterfly valve drag pump: (to be added ...)

In fact, there is no uniform standard at home and abroad. Each manufacturer has its own naming method.

37 kW (currently the smallest standard concrete pump in China, below 37 kW is a fine stone mortar pump), 45 kW, 55 kW, 75 kW, 90 kW, 110 kW, 130 kW (diesel), 132 kW, 162 kW (diesel) 174 kilowatts (diesel) ...

When choosing a large motor concrete pump, the transformer capacity must be considered first, and the distance from the concrete pump and the diameter of the wire diameter must be considered, so as to avoid excessive current drop or trip due to excessive voltage drop. Increased cost and inconvenience caused by excessive power. The motor is too small and cannot meet the needs of the project.

Relationship between concrete pump power, concrete pump outlet pressure, and concrete pump delivery volume

The motor power of a concrete conveying pump is a prerequisite for determining the outlet pressure and the amount of conveyance. With a certain motor power, an increase in pressure will definitely reduce the conveyance; on the contrary, reducing the outlet pressure will cause the conveyance. increase.

In order to ensure that the concrete conveying pump must have a large conveying capacity, and also have a certain outlet pressure and economic power matching it, in the design of concrete conveying pumps, most of the constant power plunger pumps are used; that is, constant power After the selection, when the outlet pressure rises, the output displacement of the oil pump will automatically decrease to reach the value corresponding to the power design; if you want to achieve a high outlet pressure, you also want to get a large delivery volume. The only way is to increase the motor power.

Therefore, in the new national standard, the capacity index concept of concrete conveying pumps is used (measured in MPa · m3 / h); that is, the product of the actual outlet pressure of the concrete conveying pump and the actual conveying capacity per hour, the greater the value , The greater its capacity index, the greater the power of the motor, thereby achieving the purpose of large displacement and high head. At the time of design, Konecranes also adopted the function design of high and low voltage switching to meet different construction requirements. Under economic conditions, it can produce a larger throughput, or with the same motor power, a higher Outlet pressure.

Towing pump operation regulations and precautions

First, the transportation of the pump and the retracting of the outrigger

1 When the trailer is towing the concrete pump, the pump must be retracted on the outriggers, the guide wheels must be fully retracted, and they must not be in contact with the ground. The speed of the trailer must be moderate, the speed cannot be greater than 15 kilometers per hour, and the cables must be tied firmly.

2. Operate the collection pump

(1) Operate the lifting handle of the guide wheel to retract the guide wheel upward, the front section of the chassis is lowered, and the vehicle leans forward.

(2) Lower the rear leg, insert the positioning pin of the leg, and lock the locking pin of the positioning pin.

(3) Operate the lifting handle of the guide wheel to support the guide wheel downwards, the front end of the chassis rises, lower the front leg, and insert the positioning pin.

(4) After the above operations are completed, keep the tow pump approximately horizontal, and land on four legs at the same time to ensure that the tire is not loaded, and finally retract the guide wheel.

(5) Retract pump operates the guide wheel to retract the legs in the opposite way.

(6) If necessary, use a jack to assist the income.

Before the pump works

1. Check that the tow pump is in place. The tow pump should be installed on a roughly level, solid ground with four legs at the same time, to ensure that the tires are not loaded, and the ground is soft. To prevent subsidence, add wood or wooden boards to fix it.

2. Check the laying and connection of each pipe, check whether the straight pipe is on a line, whether the pipe is reasonable, and whether the joints at each mouth are dense.

3. Check whether the water tank and hopper are filled with water.

4. Check the hydraulic oil tank oil level and whether the oil level of the grease pump oil tank is full. Manually pump oil, check whether the oil supply condition of each lubrication point is normal.

5. Check whether the cable connector is loose or broken, and whether the switches are in the "off" position, then turn on the power switch, jog the motor, and check whether the motor is turning correctly. (If the steering is not correct, the two phases should be arbitrarily replaced. Power cord is sufficient).

6. Before starting the motor, check whether the screen and bottom door of the hopper are closed and there are no foreign objects in the hopper.

7. In winter, the temperature is relatively low, it needs to run for a while, and the temperature of the hydraulic oil rises above 20C before starting to discharge and pump.

8. Dry run for 10 minutes, check whether the pressure gauge shows normal, whether the stirring device can be reversed, and whether the forward and reverse pumps operate normally.

Third, at work

1. Before pumping the concrete, first pump the water to lubricate the pipes, check whether the pipe clamps are sealed and leaking, and then pump the mortar to open the pipes.

2. After confirming that the mortar is open, stir the remaining concrete in the car and mix it well before pumping normally.

3. Contact the front-end operator when starting or stopping pumping concrete to avoid accidents.

4. During the pumping process, the concrete should be ensured above the mixing axis, and no suction or pumping is allowed.

5. During the pumping process, pay attention to the temperature of the hydraulic oil. When the temperature rises to 50C, air cooling should be started. If the oil temperature continues to rise and exceeds 80C, the machine should be shut down and inspected.

6. During the pumping process, ensure that 3-5 cars are lubricated by pulling the lubrication pump and the rotating oil cup cover (once every four hours), so that each lubrication point is well lubricated.

7. If the pumping is suspended for a long period of time, the pump must be turned on every 10-20 minutes, the reverse pump 1-2 strokes, and the forward pump 1-2 strokes to prevent the concrete in the pipe from condensing.

8. During the pumping process, pay attention to the pressure gauge. If the pumping pressure suddenly rises, immediately turn on the reverse pump button, reverse pump 2-3 strokes, and then forward the pump. If the pumping pressure is still too high for several consecutive times, It is blocked, and pumping should be stopped.

9. If the slump of the concrete is too low, it is not allowed to add water to the hopper for mixing. After adding to the tanker truck, stir and put it into the hopper and pump it evenly.

10. The hopper screen must not be filled with concrete, and the supply flow must be controlled. The hopper screen must not be filled out of the hopper, and large aggregates, soil blocks and foreign matter must be removed in time.

11. When the mixing shaft is stuck and does not turn, the pumping should be suspended to eliminate the fault in time.

12. After the vertical pumping is interrupted, re-pumping should be carried out first, so that the concrete of the distribution valve is retracted into the hopper.

13. During the pumping process, check the entire machine for abnormal noises, whether the main cylinder and swing valve cylinder are commutated normally, whether the pipe clamps and bolts are loose, and whether the joints are leaking oil.

14. When pumping the concrete, pay attention to the slump of the concrete, and contact the technical department if any abnormal phenomenon is found. Reject unreasonable excess water.

15. Pay attention not to allow the car to be crushed during the work, and use wooden blocks or trenches for protection.

16. During the command of reversing, pay attention to the distance between the vehicles and do not scratch the tow pump.

17. In the pumping gap, the concrete splashed on the pump, excess lubricant, and water splashed from the water tank should be scrubbed to ensure that the pump is clean and free of pollution.

Fourth, after work

1. After confirming that the pumping of concrete is finished, open the positive pump for 3-4 strokes and empty the remaining concrete. Stop the positive pump and use a shovel or rake to remove the residual concrete in the hopper and S pipe. Unloading door, rinse the concrete inside and outside the hopper with water, and close the door after it is cleaned.

2. Fill the hopper with water, start the positive pump to pump water, and pump the remaining concrete with the water. After the water is discharged, open the hopper door and start the reverse pump. The stones and sand that have not been pumped out flow with the water. Close the hopper door. Run for 20 minutes and continue to supply grease until the lubrication point is out of oil. After cleaning, turn off the motor, turn off the power, and cover the pump.

3. Drain the water in the water tank, especially in winter, and observe whether the water is turbid.

4. Clean and dry the whole body. There should be no concrete blocks, mortar, mud and other dirt around the body of the tow pump.

There is a pair of bevel gears on the supporting part of the concrete tow pump. One of the bevel gears is shown in Figure 1. The material is 20CrMnTi. The main technical parameters of the gear are: the large end face modulus is 4, the number of teeth is 20, and the tooth angle is 20. °, tangential displacement coefficient is 0, radial displacement coefficient is -0.27, large end tooth height is 0.8mm, accuracy grade is 8CB GB11365, root cone angle and other parameters are shown in Figure 1. Because the hardness of the tooth surface is HRC56 ~ 64, the gear needs to be carburized and quenched, and the depth of the carburized layer is 0.8-1.2mm. From the technical requirements and accuracy levels shown in the figure, the gear's processing accuracy level is not high. To ensure the processing quality of the part, the key is to solve the bevel gear processing and heat treatment process. Since the part is in the trial production stage, To reduce the processing cost, we decided to use a profiled gear milling cutter milling method on a horizontal milling machine to process the bevel gear, and to formulate reasonable heat treatment process methods and parameters to ensure the processing quality of the gear.

1 Bevel gear machining process flow and difficult point control

In order to ensure that the final heat treatment of the gear can reduce the deformation and obtain a uniform structure and good mechanical properties, before machining, the high temperature normalizing pretreatment of the gear blank can refine the structure and reduce the infiltration. Deformation of the parts during carbon quenching also helps to improve cutting performance. After normalizing, the machine is turned. After roughing and finishing the outer circle and end surface of the gear blank on a lathe, the teeth are milled on a horizontal milling machine, and then the keyway is inserted on the insertion machine. After all machining is completed, carburizing and quenching And low-temperature tempering treatment, and finally post-treatment. The technical process of this part is: normalizing turning milling key insertion slot carburizing quenching and annealing sandblasting rust prevention treatment. The technical difficulties are milling and heat treatment.

2 Processing principle of forming gear milling cutter milling method

Straight bevel gear processing by forming gear milling cutter belongs to approximate forming method. Because of the bevel shape of a straight bevel gear, it should be a spherical involute in theory. Since the spherical surface cannot be developed into a flat surface, the equivalent involute tooth profile on the development surface of the back cone is used to design the tooth profile of the forming milling cutter. Since the tooth profile of the spur bevel gear is contracted toward the cone top, the curvatures of the equivalent involute teeth on the development surface of each back cone along the generatrix of the pitch cone are different. Therefore, the tooth profile of the spur bevel gear milling cutter can only be designed according to the equivalent involute tooth profile on a back cone development surface of the pitch cone generatrix, and the processed gear profile can only be compared in a certain section. Accurate, other sections have some errors. Therefore, the spur bevel gear forming milling cutter is suitable for rough machining and machining of low-precision spur bevel gears.

3 Gear milling method and process

On ordinary horizontal milling machines, an indexing head with a rotary table is used for indexing. The specific method is to fix the tooth blank on the indexing head, as shown in Figure 2. Adjust the tilting angle of the indexing head and raise the indexing head to an angle equal to the bevel gear root cone angle f. Use the notch method to make the milling cutter. The symmetrical line of the profile is aligned with the center of the tooth blank, the cutting depth is adjusted, and the big end is used as the reference. After the table is raised to the full end height of the big end, the middle of the cogging is milled first. The thickness of the gear forming milling cutter is designed according to the cogging width slightly smaller than the small end of the bevel gear. Therefore, after the middle part of the cogging is milled, there is a certain machining allowance on the big end and both sides of the gear. Therefore, the above parts must be processed. . At this time, the indexing head base is rotated by an angle in the horizontal plane, so that the contour line of the milling cutter profile and the axis of the tooth blank are at an angle. At the same time, the horizontal table is appropriately moved (the amount of movement can be determined by trial cutting). The margin on one side of the groove is milled (Figure 3), and then the indexing head base is rotated reversely by 2, and the horizontal table is also moved in the opposite direction, and the other side of the cogging is milled. The calculation formula of the horizontal rotation angle of the indexing head base is as follows:

4 Tool selection

From the structure and technical parameters of the gear, it can be known that the bevel gear belongs to the standard structure. In general, the tooth shape of the standard straight bevel gear forming milling cutter is designed according to the large end back cone equivalent involute tooth shape, and the tooth thickness Design according to little endianness, and consider leaving some fine cutting margin. In general, there are 3, 8, 15, and 26 straight bevel gear forming milling cutters. The tool number should be selected according to the number of teeth of the bevel gear. The equivalent number of teeth Zv can be calculated according to the following formula:

5 heat treatment process method and process

As mentioned above, the gear blank is subjected to overall high-temperature normalizing treatment before machining. The normalizing equipment is an RT-90-9 box furnace. The specific process is that when the furnace temperature rises to the loading temperature of 400-650 ° C, In the gear furnace, if you need to stack parts when installing, do not stack more than two layers, then heat the parts to 920-940 , so that the tissue completely changes phase. After 30-50 minutes of heat preservation, air cooling can be used. The normalizing process diagram is shown in Figure 4:

Because the precision requirements of the gear are not very high, in order to reduce the cost of carburizing and quenching, the direct quenching process can be used. The specific method is to put the parts into the carburizing basket, do not overlap, and the furnace temperature rises to 840 ° C and starts to drip. For aviation kerosene, the kerosene dropping speed is 60-80d / min. When the furnace temperature rises to 930 ° C, parts start to be installed in the furnace. After the exhaust period, put two test rods, one of which takes out the quenching oil when the diffusion time is 120 min, cools and checks the depth of the hardened layer, and decides whether to cool down according to the test results. If the depth of the carburized layer is insufficient, The diffusion period was extended to 150 min. Carburizing can be performed in accordance with the parameters specified in Table 1. To control the carbon potential concentration during carburizing, an oxygen sensor can be installed in the carburizing furnace for monitoring and control. The oxygen sensor converts the atmosphere state through a zirconia probe. It is a potential difference. The above difference is determined and compared by the control system to determine whether the concentration of the carbon potential is suitable and automatically optimized and adjusted, so that the control accuracy of the carbon potential can reach ± 0.05% C, which can effectively control the depth of the carburized layer. And to improve the quality of the carburizing layer, to ensure that there are no block or network carburizing materials, carburizing equipment using RQ3-75-9 well carburizing furnace. After the carburizing and isothermal period is over, the parts come out of the furnace and are directly quenched. The quenching equipment uses a special constant temperature oil tank. The quenching medium is a special isothermal graded quenching oil. The temperature of the medium is constant between 110-120 ° C. After cooling for 30 minutes, the furnace is air-cooled.

In order to eliminate the residual stress of the parts after quenching and prevent the occurrence of quenching cracks, the quenched parts should be subjected to low temperature tempering as soon as possible. The specific process method is to start the furnace assembly when the furnace temperature rises to about 160 ° C and keep the temperature 120- After 150min, air cooling is released, and the tempering equipment is RJJ-36-6 tempering furnace. The quenching and tempering process diagram is shown in Figure 5:

6 Post-processing

Place the heat-treated parts on the rotary table of the sand blasting machine for sand blasting. The particle size of quartz sand is 10-20 mesh. During the blasting process, the parts must be turned frequently to make the sand blasting effect uniform on all sides. After blasting the parts, put them in the anti-rust solution for 2-4 minutes, and then dry them in the air. It should be noted that the anti-rust treatment must be completed within 24 hours after sand blasting.

7 Effects

The above method is simple and practical, and it does not require special equipment to realize the processing of straight bevel gears, and has good economy and low cost. After inspection of the processed bevel gears, the size, shape and position accuracy meet the requirements. The depth of the carburized layer is 1.1-1.3mm. The metallographic structure of the teeth is a single lath tempered martensite structure with a hardness of HRC58. -62. The hardness of the heart is HRC36-40, which can fully meet the quality requirements of this part.