The main forms of valve damage are wear, bending and skew. The reasons are as follows:

　　①氣門(mén)和氣門(mén)座圈受高溫、高壓氣體的沖擊和承受工作過(guò)程中的機(jī)械負(fù)荷，容易燒蝕和磨損。氣門(mén)與氣門(mén)座圈的工作斜面，由于氣門(mén)不停地開(kāi)啟和關(guān)閉，相互撞擊、敲打，承受反復(fù)的沖擊負(fù)荷，引起工作斜面的磨損、起槽、斑點(diǎn)和凹陷。

　　Valves and seat rings are easily ablated and worn by the impact of high temperature and high pressure gas and the mechanical load in the working process. The working incline of the valve and the valve seat ring is attacked, grooved, spotted and sunken due to the constant opening and closing of the valve, the impact and knocking of each other, and the repeated impact load.

　?、跉忾T(mén)桿部在氣門(mén)導(dǎo)管內(nèi)運(yùn)動(dòng)時(shí)不斷摩擦，潤(rùn)滑條件又差，加上竄進(jìn)的灰塵磨料，使兩者均受到磨損。

　　(2) When the valve rod moves in the valve conduit, it rubs continuously, and the lubrication condition is poor, together with the dust abrasive, which makes both of them suffer from wear and tear.

　?、蹥忾T(mén)導(dǎo)管內(nèi)進(jìn)人積炭結(jié)膠，加速氣門(mén)桿與導(dǎo)管間的磨損。

　　(3) Carbon deposit cementing is introduced into the valve duct to accelerate wear and tear between the valve stem and the duct.

　　④氣門(mén)桿尾端與搖臂之間相互撞擊，使兩者都受到磨損。

　　(4) The tail end of valve rod and rocker arm collide with each other, which makes both of them suffer from wear and tear.

　?、輾忾T(mén)頂部受氣缸內(nèi)氣體壓力、氣門(mén)桿尾端受凸輪通過(guò)挺柱的撞擊，造成氣門(mén)桿的彎曲。

　　The top of the valve is subjected to the gas pressure in the cylinder and the end of the valve rod is impacted by the cam passing through the tappet, which causes the bending of the valve rod.

　?、逇忾T(mén)頂與活塞碰撞而使氣門(mén)桿彎曲。

　　_The valve rod is bent by the collision between the valve top and the piston.

　?、邭忾T(mén)桿尾端面搖臂間的間隙過(guò)小，受熱膨脹后，頂住氣門(mén)桿尾端而使其彎曲和端面不平。

　　_The clearance between rocker arms at the end of the valve rod is too small. After being heated and expanded, the end of the valve rod is held against and the bending and end surface of the valve rod are uneven.

　　⑧氣門(mén)或氣門(mén)座圈工作面與氣門(mén)桿不同心，氣門(mén)座與氣門(mén)導(dǎo)管不同心而使氣門(mén)桿彎曲。

　　_The working face of valve or valve seat ring is not concentric with the valve stem, and the valve seat is not concentric with the valve duct, which makes the valve stem bend.

　?、釟忾T(mén)桿與氣門(mén)導(dǎo)管受磨損后，使配合間隙增大，氣門(mén)桿在管內(nèi)晃動(dòng)使氣門(mén)歪斜，引起氣門(mén)頭部的偏磨。

　　_After wear and tear of the valve rod and the valve duct, the fit clearance increases, and the valve rod sloshing in the tube causes the valve to skew, causing eccentric wear of the valve head.

　?、鈿忾T(mén)桿彎曲后，形成氣門(mén)頂部的歪斜和偏置。

　　_After the valve stem is bent, the inclination and offset of the top of the valve are formed.