The general process of reaming of diesel generator valve seat includes five aspects: reamer guide rod, sanding layer, initial hinge, trial fitting and trimming contact surface, and fine hinge. The specific process plan is:
1. Select the reamer guide rod.
According to the inner diameter of the valve guide, select a suitable reamer guide rod, and insert the guide rod into the valve guide to match the inner hole of the valve guide.
2. Abrasive the sand layer.
When there is a hard layer on the valve seat, the reamer often slides. In this case, use coarse emery cloth to grind on the reamer grinding wheel, and then ream the hole.
3. Initial hinge.
First, put the 45° reamer (steel thickness, thin blade) on the guide rod, and then align the keyway of the reamer with the flange on the lower end face of the reamer handle to ream the hole. The reamer should be straight on the reamer, the force of both hands should be even and steady, and the reaming should be rotated clockwise. When returning the knife counterclockwise, do not use force to prevent the blade from becoming blunt until defects such as ablation, spots and dents appear on the valve seat.
4. Trial and repair contact surfaces.
Preliminary tests were carried out with polished phase valves. The test method of this product is as follows: apply red dandelion oil on the conical working surface of the valve seat, put it in the guide tube and rotate it for 2~3 circles without beating, and then take out the valve to observe its contact state. The general requirements are: the contact surface is on the middle and lower side of the working slope of the valve, the width of the intake port is 1.0~2.0mm, and the exhaust valve is 1.5~2.5mm. The contact surface is too narrow, which affects the sealing and heat dissipation. Too wide is easy to deposit carbon. And it doesn't fit tightly. The correct contact position between valve and valve is shown in the figure below. The middle and lower part of the working face of the valve cone, the width is 1.5~2mm.
For the trial fitting after initial reaming, if the contact surface is on the upper side, use a 15° reamer to ream the upper port so that the contact surface moves downward. Move it up so that the contact surface is in the middle and lower part as much as possible, and the valve contact surface is lower in the middle section. Use a 75° reamer to ream it in the middle and lower parts, so that the valve contact surface is lower in the middle section. It is reamed in the middle and lower part, so that the valve contact surface is lower in the middle part. In order to prolong the service life of the valve seat and the valve seat, the reaming can be stopped when the contact surface is 1mm away from the lower edge of the valve.
5. Fine hinge.
Finally, use a 45° (or 30°) fine-blade reamer or pad on the reamer, equipped with a fine sand gasket, to finely trim the working surface of the valve seat to improve its contact surface finish. Hongdan oil is finally used for testing again, and the contact surface of the valve and the valve seat is a continuous annular belt.
Precautions for reaming of diesel generator valve seat:
Adopt valve seat reamer, adopt valve seat reamer, suitable for use on soft valve seat. Valve seat reamers usually have four types: 15°, 30°, 45°, 75° (or 60°). The 30-degree and 45-degree blades can be divided into coarse and fine blades. Generally speaking, the thick edge has a tooth shape, which can be reamed first, and then finished with a fine-blade reamer. Attention should be paid to the valve seat before reaming: Since the reaming valve seat is based on the valve guide, when reaming is required, the valve guide should be reamed before reaming. In addition, if the valve seat is reamed first, when replacing or reaming the guide tube, the center of the seat tube will be biased, resulting in the result that the valve cannot be matched with the valve seat.
The general process of reaming of diesel generator valve seat includes five aspects: reamer guide rod, sanding layer, initial hinge, trial fitting and trimming contact surface, and fine hinge. We have already explained it in detail in the previous article. It should be noted that the above methods and requirements are only the basis, and the reamer should be handled flexibly according to the special situation of the valve. During maintenance, sometimes it is encountered that the width of the valve seat is suitable, but the contact with it is too close. At this time, if a 15° reamer is used to ream the mouth, there will be a new contradiction that the contact surface is narrowed. To solve this new contradiction, when a 45° (30°) reamer is used as the reamer, the aperture of the valve will increase, so that the contact surface moves upward. Therefore, in this case, although the contact surface is too close, it can be used as long as there is a distance of 1 mm from the working surface of the valve, otherwise the valve needs to be replaced or the valve seat ring needs to be re-inserted.
It is better that the middle of the contact should be slightly downward as required, but during maintenance, sometimes due to the limitations of the seat and valve technical conditions, or considering repairing it again, it is not necessary. Usually the top and bottom are within 0.5mm. One more thing to say, the angle of the conical valve face, although most models have a 45° intake, some are 30°, so you must not make a mistake when reaming.
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