Causes And Inspection Methods Of Plane Deformation Of Cylinder Head

Deformation of cylinder block and cylinder head of diesel generator set is a common phenomenon in use. The contact plane between the cylinder block and the cylinder head is often warped. The deformation of cylinder block seriously affects the assembly quality of internal combustion engine. Due to the deformation of the cylinder block, it will cause the cylinder seal to be not tight, air leakage, water leakage and oil leakage, and even cause the gas to wash out the cylinder gasket, resulting in insufficient power of the internal combustion engine.

（1） Causes of plane deformation of cylinder block and cylinder head.

① During manufacturing, aging treatment was not carried out or the aging treatment was not sufficient. Therefore, the internal stress of the part was very large, and the internal stress was redistributed under the action of high temperature during the working process of the engine to reach a new balance, resulting in the deformation of the part.

② When the internal combustion engine works for a long time, deformation occurs around the screw hole under the action of tensile stress.

③ The tightening torque of cylinder head nuts is too large, uneven or not tightened according to the specified sequence, which makes the plane warped.

④ Remove the cylinder head at high temperature to make the plane uneven.

⑤ The cylinder head nuts are not tightened again after the new machine or the overhauled machine is warmed up.

⑥ When repairing the cylinder block or cylinder head by welding, it will be deformed due to heat.

（2） Inspection method for plane deformation of cylinder block and cylinder head. There are two common inspection methods.

1. Indicator method.

Apply a layer of display agent on the platform, and put the inspected cylinder head or cylinder block on the platform for grinding. If the display agent is evenly distributed on the plane, the plane is flat. Otherwise, the plane is uneven.

2. Measurement method.

During the inspection, stand the ruler on the side of the measured plane, and measure the gap between the ruler and the plane with a feeler gauge (multiple measurements at different positions). If conditions permit, flatness tester can be used for measurement.

The inspection standard is that the flatness error of the upper plane of the cylinder block shall not be greater than 0.05 mm within any 50 mm x 50 mm, the six-cylinder engine shall not be greater than 0.25 mm on the whole plane, and the four-cylinder engine shall not be greater than 0.15 mm on the whole plane. The flatness error of the lower plane of the cylinder head of the side-mounted valve engine shall not be greater than 0.05 mm within any 50 mm x 50 mm, the six-cylinder engine shall not be greater than 0.35 mm (cast iron cylinder head) or 0.25 mm (aluminum alloy cylinder head) on the whole plane, and the four-cylinder engine shall not be greater than 0.25 mm (cast iron cylinder head) or 0.15 mm (aluminum alloy cylinder head) on the whole plane. If the flatness error of the upper plane of the cylinder block and the lower plane of the cylinder head exceeds the above range, it shall be repaired.

Jiangsu Starlight Electricity Equipments Co.,Ltd. is a diesel generator set factory integrating product development, production, sales and installation. The company has successfully developed a series of diesel generator sets with high-tech technology, and has formed industrial production. The main products are: silent series, mobile trailer series, container series diesel generator sets. For more details, please contact us with sales@dieselgeneratortech.com.