Deji Machinery Co., Ltd.: Discussion on Selection of Cylinder for Asphalt Mixture Mixing Station

Air cylinder plays a vital role in Asphalt Mixing Plant.，Vibrating and sieving cylinder、Hot bin cylinder、The bone is called the cylinder、Air cylinder of mixing pot、Whether the selection of finished product bin discharge cylinder is reasonable，It directly affects the operation of the whole equipment.。If the cylinder bore is selected small，The output force is not enough，Cylinder does not work properly；But the cylinder bore is too large，Not only makes the equipment bulky,、High cost，At the same time, the air consumption increases，Causing energy waste。In general，The Asphalt Mixing Plant is basically in a state of uninterrupted operation throughout the day.，If one cylinder is faulty，Directly affect the production of the whole asphalt mixing station，Cause cost loss。Through the selection of finished product warehouse cylinder，Provide some references for cylinder selection。

The theoretical output force of the cylinder is the actual output force in the most ideal state.，Is not leaking at all.、Completely free of resistance and losses.，However, there will be friction losses in practice.、Loss of air pressure, etc。Therefore, the actual output force is less than the theoretical output force.。Generally, the design and selection are based on 50% of the theoretical output force%-70%To select the type。

The most important data of the cylinder is the cylinder bore and stroke.，The output force of the cylinder is mainly related to the force area of the piston.，The forced area of the cylinder depends on the bore of the cylinder，Generally speaking，The bore of the cylinder is proportional to the stroke.，The longer the journey，The cylinder bore should also be larger.。Selection of cylinder，First of all, the piston area of the cylinder should be converted according to the required output force.，ByAvailable：In the formula：FOutput force required for 0 cylinder，N；PSystem pressure，Pa；SPiston area，㎡；NSafety factor，Generally, the horizontal use of the cylinder is 0..7，Take 0 for vertical use.5。Calculate the piston area of the cylinder，According toCalculate the bore of the cylinderD。For safety reasons，In general, after calculating the cylinder bore,，The cylinder bore value that is one level larger than the calculated value is selected。The stroke of the cylinder can be preselected according to the stroke required for the full opening of the bin door，For installation and debugging，Appropriate margin shall be reserved for the preselected stroke.，The air cylinder of the Asphalt Mixing Plant is controlled by air pressure，Therefore, the cylinder generally uses the full stroke or selects the appropriate stroke according to the actual situation.，In this way, the delivery speed can be guaranteed，Reduce costs。

Example calculation and verification

The key of the calculation is to analyze the cylinder load.，The physical properties of the asphalt mixture shall be considered in the stress analysis—Internal friction and adhesion of material particle，In order to simplify the calculation and facilitate the verification，With door open horizontallyCPGTake 120 finished product warehouse as an example to calculate.。

Density of asphalt mixtureρ=1800-2200Kg/m³，Take the maximum value in the calculationρ=2200 Kg/m³；It has been verified by many literatures.，The friction coefficient between ordinary steel plate and concrete can be roughly taken as 0..6，Therefore, the friction coefficient between the asphalt mixture and the silo is taken.μ0=0.6。The average pressure acting on the horizontal discharge gate can be approximated byp=5.6k0RHρg，In the formula：RHHydraulic radius of discharge opening，m；ρBulk density of material，kg/m³；gGravitational acceleration，m/s²；k0 Factor to take into account silo operating characteristics，For silos that are not completely emptied throughout the job，Takek0=1；For silos that are not all emptied at each opening，Takek0=1.5；For silos that are emptied every time they are opened，Takek0=2。CPGThe gate of the 120 finished product bin is horizontal.，The barn mouth is rectangular，Size 400mm×850mm，Finished product silos are not all emptied during unloading，Sok0=1.5；The calculation proceeds as follows：=24630.14PaThe friction force for opening the compartment door is:：=5024.55NThe force required by the cylinder to open the silo door is at mostF0=f=5024.55NCPGThe gate of the 120 finished product bin is horizontal.，Taken=0.7，System pressure is 0.8MPaAnd 1MPaTime，Calculated separately：=㎡=㎡ByAvailable：D₁=107mm，D₂=96mmThe cylinder with the standard bore selected from the cylinder list is 125mm。Piston to push rod diameter ratio in generald/D=0.2~0.3，The diameter of the cylinder push rod is selected within the range of 25~40mm。CPG120 The door of the finished product bin is fully opened, and it needs to move at least 400mm，Therefore, the stroke of the selected cylinder should be greater than 400mm，So select the standard travelL=500mm。

During the above calculation and analysis，Density of the mixρ，Safety factorn，Coefficient of frictionμ，kThe value of 0 will have a certain deviation.，Different forms of cabin doors have different stress conditions.，Different values lead to a certain deviation in the calculation results.，However, it can provide some theoretical basis and reference for our cylinder selection.。

According to the actual application of the cylinder in the asphalt mixing station,，Several points for attention are summarized as follow：

01

Medium for normal operation of the cylinder、The ambient temperature is generally-20~80℃，The working pressure is generally 0.1~1.0MPa。

02

The cylinder should be at 1 before installation.Check for air leakage at 5 times of working pressure。

03

Pressure regulating valve shall be provided at the inlet of air source.、Filter、Oil atomizer，O as to facilitate the lubrication during the operation of the cylinder.，If the selected cylinder is lubrication-free，Regulator and filter can be considered only。

04

When installing the cylinder，Pay attention to the direction of cylinder movement，The piston rod shall not be subjected to eccentric load and transverse load。

05

When there is a load change in the stroke，Cylinders with sufficient power output shall be used，With an attached buffer device。06
The stroke of the cylinder shall be selected according to the actual situation.，Pecially when the piston rod is extended，Do not allow the piston to strike the cylinder head。

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