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发表于 2007-11-12 20:19
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来自： 中国上海
就是螺旋桨插到screwshaft里，有个叫做contact inspection的检验，来看接触得好不好，就用蓝油。一般要求接触面不少于80%-90%。
2.4.13. Contact Inspections
(a). Prior to the fitting of tapered components, propellers for example, the degree of contact between the surfaces should be evaluated. The yard is to produce a detailed fitting procedure which can be reviewed and agreed by the Surveyors. Any subsequent deviation from that procedure should be discussed prior to any inspections taking place.
(b). Contact checks are to be carried out using a suitable medium (“engineers” blue or “red lead”) to one surface and then bringing the two surfaces together to transfer the medium to the second surface to indicate the contact extent and its pattern. The contact medium should be applied as thinly and as evenly as possible across the reference surface with a roller, not a brush. Excessive contact medium will lead to incorrect evaluation. An indication of this is that the excess blue or red lead has ‘picked up’ (i.e. peaks of fluid are visible on the surface).
(c). The components should be brought together without force fitting using the components own weight if it is fitted vertically or a manually pushed trolley if carried out in the horizontal position.
(d). Pt 3, Ch 13, 2.4 of the Rules for Ships requires that a contact area of 90% of the theoretical area of contact is to be achieved for rudder couplings where a rudder is connected by a keyless fit to the rudder stock cone. For other connections where a minimum contact area has not been specified or agreed with the shipyard 80 – 90% contact should be achieved. This should be even all over the entire contact area and particular attention should be paid to the upper third of the taper.
(e). After parting the components to check the fit, the contact compound should have a “mottled” appearance (see Figure D.3.2.3). Attention should be paid to contact areas in way of hydraulic pressure oil grooves, such as those that can be found on the inside taper of some propellers, where satisfactory surface contact is required to allow effective wet-fit of components.
螺旋桨装配
5.2.7. Fitting of propeller.
(a). The fit of the screwshaft cone to both the working and any spare propeller is to be witnessed by the Surveyor. Generally, a satisfactory fit for keyed type propellers should show a light, overall marking of the cone surface with a tendency towards heavier marking in way of the larger diameter of the cone face. The final fit to cone should be made with the key in place. Any hand fitting required should be carried out by scraping the bore of the propeller; under no circumstances should filing of the shaft cone be resorted to.
For guidance the following values of axial push-up may be used, measured from a reliable zero mark obtained from the initial bedding and related to a one in 12 taper:
Aluminium bronze 6/1000 of the diameter of screwshaft at top of cone
Manganese bronze 5/1000 of the diameter of screwshaft at top of cone
Cast steel & S.G. iron 4/1000 of the diameter of screwshaft at top of cone
Cast iron (grey or low alloy) 2,5/1000 of the diameter of screwshaft at top of cone.
(b). Keyed propellers tightened by use of a hydraulic nut. The use of hydraulic nuts is more common and such nuts are capable of producing axial forces much greater than other methods of tightening. Care should be exercised to ensure that the propeller hub is not overstressed in way of the keyway and that the root radius of the keyway and the radius at the large end of the bore of the propeller meet Rule requirements.
Shipbuilders should be requested to state the proposed axial pull-up of the propeller on the shaft when submitting plans of propellers. It is recommended that the root radii of the keyway in the propeller hub should be dye-checked for cracks after final shop fitting of the propeller to the shaft.
(c). Sealing of the propeller’s shaft cone (Keyed propellers). When fitting the propeller to the shaft in the ship, it is of the greatest importance that access of water to the propeller cone should be prevented. Particular care should be taken to ensure effective sealing at this position and the Surveyor should satisfy himself on this point. Where the sealing arrangements consist of a rubber ring completely enclosed in a recess in the propeller boss, ample provision shall be made for the displacement of the rubber.
If an approved type oil gland is fitted, particular attention should be paid to the arrangement for preventing ingress of water to the shaft cone and in this respect the following points should be emphasized:
It is essential to verify that rubber rings for forming the seal between the flange of the oil gland sleeve and the propeller boss are of the correct size and properly supported in way of the propelIer keyway.
The fairwater cones protecting propeller nuts and the flanges of sleeves of oil glands should be machined smooth and fitted with efficient joints at their connections to propellers.
Shipbuilders and propeller manufacturers should be discouraged from drilling holes through propeller bosses but, where these are essential to the design, special attention is to be paid to the efficient plugging of the holes.
The arrangement for locking all screwed components is to be verified.
The propeller boss should be provided with adequate radius at the large end of the bore.
Where the design of the oil gland attachment to the propeller is similar to that shown in Fig. D.3.5.4, it is good practice to subject the propeller boss to a low pressure air test, checking all possible sources of leakage with a soapy water solution in order to prove tightness.
(d). Keyless propeller assemblies. Surveyors should pay particular attention to the mounting of keyless propeller assemblies to ensure that the designed and approved interference fit is attained. The requirements of Pt 5, Ch 7 of the Rules for Ships are to be complied with in all cases. When dealing with the plans, the local engineering Plan Approval Office will advise the Surveyors of the `start point’ loading to be applied and the axial travel, or ’push-up’ required for that particular assembly, at component temperatures of 0°C and 35°C respectively. Assembly temperatures between these values will normally apply during the actual shop fittings and the push-up values for these temperatures are obtained by interpolation. The final marking of the screwshaft cone fit is to be submitted for the Surveyor’s acceptance and should show a generally mottled pattern over the entire surface and length, rather than the customary accepted practice of a harder marking at the large end of the cone. Keyless propeller assemblies may be mounted by a dry press-fit without fluid injection or the mounting can be facilitated by expanding the boss by means of injected fluid pressure. These are the two basic methods of fitting. With both methods the propeller is pushed up the shaft cone by means of a hydraulic nut, but the fitting procedure differs somewhat between the two methods. In all cases, the manufacturer’s fitting instructions should be complied with. The method of pushing the propeller up to the start point, calculating the actual distance moved from the point of zero load and then taking this distance into account when completing the final push distance is NOT applicable. The manufacturer’s instructions must be closely followed in all cases. If there is any doubt concerning the practice to be followed, Surveyors should seek advice from senior colleagues or the appropriate local engineering Plan Approval Office. It is also essential that each propeller (both working and spare) has the following information hard-stamped on the outside of the boss:
Oil injection type
Start point load.............................tonnes
Axial push-up at 0°C...................mm
Axial push-up at 35°C.................mm
Identification mark on associated screwshaft
Press fit type (Dry)
Start point load.............................tonnes
Push-up load 0°C.......................tonnes
Push-up load 35°C......................tonnes
Axial push-up 0°C.......................mm
Axial push-up 35°C.....................mm
Identification mark on associated screwshaft. |
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