Thermoforming is a manufacturing process used to shape plastic sheets into various custom design products. It involves heating a plastic sheet until it becomes pliable, then using a mold or a vacuum to form it into the desired custom shape.
Thermoforming and vacuum forming are both processes used to shape plastic sheets into specific forms. However, there are some differences between the two techniques:
Thermoforming is a versatile process that is widely used in industries such as packaging, automotive, aerospace, and medical. It offers advantages such as cost-effectiveness, quick turnaround times, and the ability to produce complex shapes with high precision.
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(1) Check the inside leakage of the boom cylinder. The easiest way is to raise the boom to see if there is a clear and free fall. If the drop is obvious, check the cylinder for disassembly and replace the seal if worn.
(2) Check the valve. First, clean the safety valve and check if the spool is worn out. Replace it if worn. After the installation of the safety valve, if there is still no change, check the condition of the valve core of the pilot valve. The clearance limit is 0.06mm, and the wear should be replaced.
(3) Measure the pressure of the excavator hydraulic pump. If the pressure is low, then adjust, and the pressure can not be adjusted, then the hydraulic pump is seriously worn.
In general, the main reason that causes the boom load to fail to increase is:
a. Excavator hydraulic pump is seriously worn. When the pump is running at low speed, the leakage in the pump is serious. At high speed, the pump pressure slightly increases. However, due to the wear and internal leakage of the pump, the volumetric efficiency drops significantly and it is difficult to reach the rated pressure. The long time working of the hydraulic pump exacerbates the wear and causes the oil temperature to rise, which causes the wear of the hydraulic components, the aging and damage of the seal, the loss of the sealing ability, the deterioration of the hydraulic oil, and ultimately the failure.
b. The selection of hydraulic components is unreasonable. The boom cylinder specifications are 70/40 non-standard series, and the seals are also non-standard parts. The manufacturing cost is high and the seal replacement is inconvenient. Boom cylinder bore is small, it is bound to set the system high pressure.
c. The design of the hydraulic system is unreasonable. The control valve and the hydraulic steering gear are connected in series with a single pump. The safety valve setting pressure is 16 MPa, and the excavator hydraulic pump's rated working pressure is also 16 MPa. Hydraulic pumps are often operated under full load or long-term overload (high pressure) conditions, and the system has hydraulic impact, long-term oil change, hydraulic oil contamination, exacerbated hydraulic pump wear, resulting in hydraulic pump casing burst (later discovered Such failures).
Improvements and Effects (l) Improve Hydraulic System Design. After many arguments, the advanced priority valve and load sensing full hydraulic steering gear form were used. The new system can prioritize the distribution of traffic according to the steering requirements, ensuring that the fuel supply is adequate regardless of the size of the load and the speed of the steering wheel. The rest of the system can be supplied to the working device circuit to eliminate power caused by excessive oil supply to the steering circuit. Losses increase system efficiency and reduce the work pressure of excavator hydraulic pumps.
(2) Optimize the design of boom cylinders and hydraulic pumps to reduce system operating pressure. With optimized calculations, the boom cylinder uses the standard series 80/4. The displacement of the hydraulic pump was increased from 10 ml/r to 14 ml/r, and the system set pressure was 14 MPa, which satisfied the lifting force and speed requirements of the boom cylinder.
(3) In the process of use, attention should also be paid to the correct use and maintenance of the loader, adding or replacing hydraulic oil on a regular basis, maintaining the cleanliness of hydraulic oil, and strengthening daily inspection and maintenance.
1. Process: In thermoforming, a plastic sheet is heated until it becomes pliable, and then it is pressed against a mold using pressure or a vacuum. Vacuum forming, on the other hand, relies solely on the use of a vacuum to draw the heated plastic sheet onto the mold.
2. Mold complexity: Thermoforming is typically used for more complex shapes and intricate molds, as it allows for greater detail and precision. Vacuum forming, on the other hand, is better suited for simpler shapes and molds that do not require as much detail.
3. Material thickness: Thermoforming is often used for thicker plastic sheets, typically ranging from 0.030 to 0.250 inches in thickness. Vacuum forming is more commonly used for thinner plastic sheets, typically ranging from 0.005 to 0.060 inches in thickness.
4. Production volume: Thermoforming is generally more suitable for high-volume production due to its faster cycle times and ability to handle larger sheets of plastic. Vacuum forming is better suited for low to medium volume production, as it has slower cycle times and is limited by the size of the vacuum forming machine.
5. Cost: Thermoforming typically requires more expensive equipment and molds, making it a more costly process compared to vacuum forming. Vacuum forming, on the other hand, is a more cost-effective option for smaller production runs or prototypes.
Overall, thermoforming is a more advanced and versatile process that offers greater precision and complexity, while vacuum forming is a simpler and more cost-effective option for less complex shapes and smaller production volumes.
Explain the excavator hydraulic pump wear and post treatment method
Excavator hydraulic pump after severe wear and tear treatment After the excavator hydraulic pump is seriously worn, we use the following three points to find the cause of the fault and improve the system: