Design and rationality analysis of the hottest wal

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Design and rationality analysis of walking excavator

walking excavator (hereinafter referred to as walking excavator) is composed of working device, boarding, slewing mechanism, alighting, power device and hydraulic system, as shown in Figure 1. It is mainly used for the excavation of earthworks such as housing foundation trench, various pipelines, cable trenches and canals. The difference between the walking excavator and the ordinary excavator is that there is no walking machinery when getting off the vehicle. The whole machine is supported by four outriggers, and the forward, backward and steering are realized by the combined action of the working device and the rotary mechanism. Therefore, the design difference between it and the ordinary excavator is mainly in the getting off part. This paper discusses this. Due to the unique structure of the walking excavator, the following requirements should be considered when determining the structural parameters: ① the whole machine has high stability and good excavation in the whole area (360); ② Good walking performance, and can drive into the construction site without roads; ③ Outrigger adjustment is simple and rapid, with strong adaptability to the ground, safe and reliable; ④ Small walking excavators can get on and off the transportation vehicles by themselves when they move for a long distance; ⑤ The upper part of the claw of the outrigger is a horizontal plate, and the lower part is a radial claw, so as to avoid the outrigger sinking and the horizontal movement of the whole machine during excavation; ⑥ Be able to excavate in a narrow site close to the corners of the building; ⑦ Tyres shall be equipped with braking devices or anti-skid devices. 1. The design of the lower carriage consists of chassis, outriggers and outrigger seats. Each outrigger is operated by a hydraulic cylinder. The front two outriggers are equipped with a pair of claws, and the rear two outriggers are equipped with a pair of walking wheels. In order to meet the requirements of the operation of the walking excavator, getting on and off the vehicle and trafficability, the four outriggers should be able to adjust their length and support position in longitudinal, transverse and vertical directions, as shown in Figure 2. The length of the four legs and the adjustment size in the horizontal plane mainly affect the lateral and longitudinal stability of the walking machine and the trafficability when walking (through a narrowest road section). At the same time, considering that the requirements of the walking machine for the lateral and longitudinal stability are close, therefore, the ratio between A1, A2, B1, B2, is generally taken as: a2/a1= 5,b2/b1=. 5,b1/a1=1.. 3,b2/a2=1.. 3。 In order to adapt to the variable size of the operation site and operation conditions, the front outrigger is composed of two retractable sections, whose length can be adjusted by the block, and the expansion ratio λ Lmax/lmin=1.8 the proven Solvay tecnoflon pl855 fluororubber (FKM) also gives fasteners better chemical resistance and high temperature resistance -1.9; The length of the rear outrigger is about the length of the front outrigger in the retracted state. There is a locating pin hole on each outrigger seat, so that the front and rear outriggers can be adjusted in the horizontal plane, which can meet the stability requirements under different operating conditions. The movement of the four outriggers in the vertical direction is controlled by four hydraulic cylinders, which can be adjusted steplessly. The upper and lower adjustment dimensions of the outrigger should not only meet the requirements that the walking excavator can level the upper vehicle when working on uneven slopes, but also mainly improve its impact strength and elongation, solvent resistance, environmental resistance, processing performance and electroplating ability to meet the requirements of the upper and lower transportation vehicles. When the walking excavator goes up and down the transport vehicle, the maximum length and angle of the front outrigger can be adjusted to make the upper leveling and the lower part of the lower substructure mm higher than the transport vehicle, as shown in Figure 3. Therefore, the maximum angle (generally taken) of the front outrigger downward adjustment should be coordinated with the maximum length. The annual output is 71million tons; The utilization rate of nitrogen fertilizer production capacity is about 90% of the national average. The excessive downward adjustment angle of the front outrigger causes the force arm of the outrigger cylinder to be too small and the hydraulic cylinder to be under too much force. Unfavorable to hydraulic cylinder; Too small is not high enough. Adjust the size of the rear outrigger upward to make the lower edge of the walking wheel higher than the lower part of the base 1. Nokia's understanding of plastic has reached a magical level mm, and adjust the size h1= (2/3~1/4) H3 downward. The front outrigger adjusts the dimension h4= (2~3) H2 upward. In order to prevent the outrigger from sinking and the whole machine from moving horizontally, the upper part of the outrigger is a horizontal plate and the lower part is a radial claw. The outrigger must have a certain support area to prevent the outrigger from falling into the ground too much when the walking excavator is working, and it can clean up the accumulated soil by itself. The walking wheels on the two rear legs need to be equipped with braking devices, and the wheels can use rubber wheels with good walking performance; Steel wheels are also available at a low price. When using tires, it is recommended to use auxiliary support claws, as shown in Figure 4. By adjusting the auxiliary support claw of the rear outrigger to lift the tire off the ground and reduce the stress on the tire, it can not only prevent skid, but also eliminate the brake device, and you can also choose a tire with small bearing capacity. By adjusting the angle of the rear outrigger, the auxiliary support claw is lifted off the ground, and the walking of the walking excavator is not affected. 2 rationality analysis of design 2.1 the exertion of excavation force the quality of excavator design can be measured from the exertion of excavation force, power utilization, productivity and working size. The walking excavator is a small excavator based on bucket excavation. After the bucket mechanism is determined according to the designed soil resistance and the working device size is preliminarily determined according to the working size, the force on the boom and stick has been determined. It is obviously uneconomical and unnecessary in practice to ensure the full play of the excavation force within the scope of the entire envelope diagram. The relatively economic and reasonable treatment principle is to ensure that the excavation force is fully exerted in the main excavation area, which is not limited by the locking ability of the passive oil cylinder, the stability of the whole machine and the attachment of the ground. The excavation area with the most common working posture in the excavator operation is the main excavation area, as shown in Figure 1. For the exertion of non main excavation force, the requirements can be appropriately reduced as needed and possible, and the matching of each oil cylinder is allowed to be slightly poor. In addition to less excavation in these areas, the exertion of excavation force will be limited by the stability of the whole machine and the locking capacity of the oil cylinder, which are more prominent in the walking excavator. The walking excavator has no walking mechanism and relies on the combined action of the working device to realize the forward, backward and up and down transportation of the whole machine

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