What problems should be paid attention to in the installation of ship main engine?

Chapter I Installation of Ship Main Engine

learning target

Knowledge target

1. Master the work content of host installation;

2. Learn the contents and methods of pedestal preparation;

3. Learn the method of hoisting the main engine;

4. Master the positioning method of the main engine: positioning according to the shafting flange; Positioning according to the theoretical center line of shafting;

5. Learn the method of soil mechanical fixation;

6. Master the installation method of large low-speed diesel engine.

capability goal

1, the pedestal is ready;

2, can lift the host;

3. The host will be located;

4. Can repair the mainframe;

5. Be able to disassemble and assemble parts of large low-speed diesel engine: engine base, main bearing and crankshaft, engine block, cylinder block and piston.

Plug device and cylinder head.

Section 1 Overview

The marine main engine is the core of the marine power plant, and its installation quality will directly affect the normal operation of the power plant and the navigation performance of the ship.

The main types of main engine are diesel engine, steam turbine and gas turbine. Different models of main engines have different structural characteristics and working modes, so corresponding technological methods should be adopted according to different models when they are installed on board. Diesel engine is the most widely used main engine at present. This chapter mainly discusses the installation technology of diesel engine main engine.

The power generated by the main engine is transmitted to the propeller through the shafting, and the main engine is connected with the shafting. The main engine, shafting and propeller are an organic whole, and the installation of the main engine should be considered together with the installation of shafting. When shipbuilding, there are three installation orders of the main engine and shafting: first install the shafting, then install the main engine; Install the main engine first, and then install the shafting; Main engine and shafting are installed at the same time. It is a long-standing installation technology to install shafting on the slipway first, and then install the main engine based on shafting after the ship is launched. Because this method is easy to make the rotation center of the main engine output shaft coaxial with the rotation center of the shafting, and it also avoids the influence of hull deformation after the ship is launched. The disadvantage of this method is that the production cycle is long. On the slipway, based on the theoretical center line of shafting, the main engine and shafting are installed first, and then the position of shafting is determined according to the actual position of the main engine to install shafting. The main engine and shafting can also be installed simultaneously. By adopting this method, after the main engine is positioned, the pipeline system and various auxiliary equipment can be installed, which expands the installation working face and shortens the production cycle. However, this method is often difficult to avoid the influence of hull deformation after launching, and when installing shafting, the deviation caused by the fixing of main engine and stern shaft must be digested by shafting, which increases the constraint conditions and makes the installation more difficult. In engineering practice, which installation sequence should be adopted depends on the general shipbuilding technology, the actual conditions of the factory and the construction period.

After the installation of the main engine, it is necessary to ensure that the relative position between the main engine and the shafting is correct and maintain this relative position relationship during operation. In order to prevent other factors from affecting the installation quality of the host, the following work must be completed before the installation of the host:

(1) The transportation and installation of the main engine and shafting of main equipment such as ship structure and superstructure are basically completed in this area.

(2) The water pressure test of all cabins and double-bottom cabins from the engine room to the stern shall be completed.

The work of host installation can be summarized as follows:

(1) Preparation of the main engine base (base).

(2) Positioning (alignment) of the host.

(3) Fixation of the host.

(4) Quality inspection.

Section II Preparation of Host Base (Base)

The main engine is installed on the hull base through gasket or shock absorber, and the base is a bearing seat directly connected with the hull. According to different models, there are generally two forms of base. For a large low-speed diesel engine, there is no separate tomb seat, and the double bottom of the engine room is welded by a thickened steel plate, and the main engine base is located on this thickened steel plate, as shown in figure 1- 1. Small and medium-sized diesel engines usually have a protruding oil pan, so a metal component welded by section steel and steel plate is needed on the double bottom, as shown in figure 1-2. The fixed gasket is welded on the panel to reduce the machining surface, and the movable gasket is installed between the fixed gasket and the diesel engine base to adjust the height of the main engine. The main engine and the base are fixed together by bolts. Chapter II Installation of Ship Shafting

learning target

Knowledge target

1. Master the function and composition of shafting and the installation requirements of typical structures;

2, master the technical conditions of shafting parts manufacturing and assembly;

3. Master the main contents of shafting installation technology;

4. Learn the methods to determine the theoretical center line of shafting: steel wire drawing method and optical instrument method;

5. Learn the boring of shafting holes: machining and checking the determination of arc lines, the technical requirements of boring, boring devices and boring.

Installation and drilling technology of ship exhaust fan;

6. Understand the installation of exhaust tailpipe device;

7. Grasp the significance and methods of shafting alignment: shafting alignment according to straightness, shafting alignment according to allowable load on bearing and shafting alignment according to bearing.

Reasonable alignment of ship shafting;

8. Learn the methods of shafting installation: shafting connection, intermediate bearing fastening and installation quality inspection.

capability goal

1. will determine the theoretical centerline of the shafting;

2. Drill shaft holes;

3. The tail pipe device can be installed;

4. The shafting can be calibrated;

5. The shafting can be installed correctly.

Section 1 Overview of Ship Shafting System

I. Function and composition of shafting

The function of ship shafting is to transfer the power of main engine to propeller; The axial thrust generated by the rotation of the propeller is transmitted to the thrust bearing through the shafting, and then transmitted to the hull by the thrust bearing, so that the ship can move forward or backward. Therefore, the ship shafting is one of the important components of the ship power plant. The quality of shafting will directly affect the normal navigation of the ship and is directly related to the operation of the main engine. Therefore, the manufacture and installation of shaft system have high technical requirements and must conform to the relevant provisions of technical standards.

Ship shafting usually refers to the transmission device from the flange at the end of the main engine crankshaft (or the end of the gearbox) to the tail shaft (or propeller shaft). Its main components are: thrust shaft and its bearing, intermediate shaft and its bearing, tail shaft (or propeller shaft) and tail bearing, herringbone frame bearing, tail shaft tube and sealing device, and couplings of each shaft. Some ships also have short shafts to adjust the length of shafting. In addition, there are bulkhead stuffing boxes and belt brakes.

There are many kinds of shafting structures, including commonly used propeller propulsion shafting; Shafting of propeller propulsion device with adjustable pitch; Shaft system of forward and backward propeller propulsion device; Rotating propeller propulsion device shafting, etc. They are completely different from each other. However, as far as civil ships in China are concerned, most of them belong to the commonly used propeller propulsion shafting except engineering ships and some inland boats. Therefore, this book only introduces the manufacturing and installation technology of shafting of commonly used propeller propulsion device.

Civil ships generally adopt single shafting or double shafting, while passenger ships generally adopt double shafting. The single shafting is located in the longitudinal section of the ship, while the double shafting is located on both sides of the ship and is symmetrical to each other. Twin-shaft ships have good maneuverability and strong vitality, and are mostly used in inland rivers. However, the structure of the two-axis ship is complex, the construction workload is large and the cost is high.

According to the requirements of the main engine and propeller arrangement, sometimes the axis is inclined to the baseline. Or at an oblique angle beta to the longitudinal section. The tilt of the shafting makes the main engine in a bad working state and reduces the effective thrust of the propeller. In order to prevent the propeller's effective thrust from dropping significantly and ensure the safety and reliability of the main engine, the α angle is generally limited to 0 ~ 5, while the β angle is limited to 0 ~ 3. For ordinary speedboats, due to the limitation of conditions, the α angle can reach 12 ~ 16, but rarely exceeds 16. For single-axis ships, the shafting is usually parallel to the vertical line (or keel line), that is. α = 0, but twin-shaft ships rarely meet the requirement of no inclination.

In the design of the general rest of the ship, the engine room can be arranged in the middle or at the stern. When the engine room is arranged in the middle, the shafting is longer; When the engine room is arranged at the rear, the shafting is relatively short. -Generally speaking, shafting with two or more intermediate shafts is called long shafting, and the shafting length of large ships with medium machinery punishment reaches 100m, among which there are more than ten intermediate shafts; There is only one shafting, the length can be as short as 7 ~ 8m, or shafting without intermediate shaft is called short shafting. Long shafting is flexible and easy to trim, but the adjustment and installation workload is large. The stiffness of short shafting is relatively large, so the installation requirements are relatively high. For a twin-shaft ship, the rotation directions of the left and right main engines must be opposite. When the ship is moving forward, the starboard main engine usually turns right and the port main engine turns left. If the main engine rotates in the same direction, it can be achieved by reversing gears. When the main engine drives the left and right shafting, reversing gears can also be installed to make the left and right shafting rotate reversely.

When the thrust bearing is installed in the main engine or gear box, it is not necessary to install an independent thrust bearing in the shafting. The thrust shaft and its bearings have two functions: one is to bear the axial thrust generated by the propeller and transmit it to the hull to make the ship move; The second is to prevent the axial thrust generated by the propeller from directly pushing the crankshaft of the main engine, causing the crankshaft to move askew, thus damaging the main engine parts.

There are two kinds of common thrust bearings, one is horseshoe thrust bearing, which is common on old ships; The other is single-ring thrust bearing (also known as Michele thrust bearing), and the former has been eliminated.

The function of bulkhead stuffing box is to keep the bulkhead watertight when the shafting passes through the bulkhead, so as to ensure the sinking resistance of the ship. When the engine room is arranged at the rear, bulkhead stuffing boxes are not needed.

In a twin-shaft ship, the shafting is generally equipped with a braking mechanism. This is to stop a set of power devices with a braking mechanism when sailing, so that the shafting will not rotate due to the influence of water flow. In addition, the braking mechanism can also help the main engine shorten the commutation time.

Generally stern tube has two bearings, the front bearing is short and the rear bearing is long. Some large ships have short stern tubes, so only one stern tube bearing is provided. At this time, the head end of the tail shaft is often provided with an intermediate bearing type front bearing, which is convenient for maintenance and management. There are also some ships with a long stern tube and three stern tube bearings. Linear bearing is mostly a sliding bearing. When linear bearing is made of iron pear wood, rubber, laminated board and nylon, water is used as cooling lubricant. At this time, the stern shaft is usually protected by copper protective sleeve or FRP protective layer to prevent seawater from corroding the stern shaft. Old ships often use outboard water for natural cooling, which is easy to cause "dead angle" of poor water flow, and often causes rapid wear and tear of shafts and bearings due to sediment entering the stern tube. Therefore, modern ships adopt forced lubrication and cooling with pressurized water to overcome the shortcomings of the third chapter assembly of ship shafting components.

learning target

Knowledge target

1. Master the types of detachable couplings and their installation techniques;

2. Master the technological method of shafting pairing;

3. Master the assembly method of stern tube device.

capability goal

1. A detachable coupling can be assembled;

2. Butt the flat shaft;

3. The liner device can be assembled.

Section 1 Assembly of Detachable Coupling

Detachable couplings are widely used in shafting for installing rolling bearings, or in ships where stern shafts must be installed from outside the hull. There are many forms of detachable coupling for ship shafting, including flange detachable coupling, jacket coupling, hydraulic flange coupling and hydraulic detachable sleeve coupling.

I. Processing and Assembly of Flange-type Detachable Coupling

Flange detachable coupling is often used to connect tail shaft and intermediate shaft, which is a form of rigid coupling. According to the shape of bolt holes on the connecting flange, it can be divided into two types: cylindrical bolt detachable coupling and conical bolt detachable coupling.

Figure 3- 1 shows the cylindrical bolt detachable coupling. This kind of coupling has flange edge, so it is called flange detachable coupling.

1, technical requirements for coupling processing

(1) First, rough process the outer surface of the coupling and the end face of the flange, leaving a margin of 3 ~ 5 mm, and process the inner hole with the conical part of the shaft (taper template can be used for measurement during processing). After grinding the conical part of the coupling and shaft, turn the tail shaft on the lathe, and then add the coupling excircle and flange end face. The roughness and other technical requirements of the coupling are the same as those of the integral flange.

(2) The width, height and parallelism with the axis of the keyway on the coupling are the same as the machining requirements of the keyway on the shaft.

2. Technical requirements for coupling assembly

(1) The contact between the cone hole of the coupling and the shaft cone should be good, and the contact area should be above 75%. Check with colored oil, at least three points every 25mm×25mm. When the thickness gauge checks the big end of the cone, the insertion depth of the thickness gauge of 0.03mm should not exceed 3mm. There are 1 ~ 2 small blank areas on the contact surface, but the total area should be less than 15% of the cone surface area, and the maximum length and width should not exceed110 of the cone surface diameter at this point, and they should not be distributed on the same axis or circumference.

(2) The contact area between Ping Jian and both sides of shaft keyway is not less than 75%. When mating with the keyway of the coupling, the thickness gauge of 0.05mm should not be inserted into 85% of the length, and the thickness gauge of 0. 1mm should not be inserted into the rest. Ping Jian should be in contact with the bottom of keyway; The contact surface is not less than 30% ~ 40%.

(3) After the coupling flange bolt is installed, the 0.05mm thickness gauge should not be inserted into 90% of the joint surface, and its contact area should not be less than 75%.

(4) When installing the coupling, the thread of the conical part of the shaft should be retracted into the conical hole by a distance α (Figure 3-1);

Second, the clam shell coupling processing and assembly

Clam-shell coupling consists of two steel semi-cylinders, which transmit torque through the friction between clam shell and shaft and key. The cross-section size of the jacketed coupling is relatively small, so it is not necessary to move the shaft when disassembling, so it can be installed in a narrow and inaccessible place, but its use is limited due to its heavy weight, as shown in Figure 3-2.

1. Technical requirements for coupling processing

(1) After machining, the roundness and cylindricity of its inner circle shall meet the requirements in Table 3- 1.

(2) When the length of the sheath exceeds twice that of the journal, the taper error is allowed to increase by 0.01mm.. The diameter of its inner ring should be 0.04 ~ 0.08 mm larger than the diameter of the journal. The spacing between the two halves of the coupling should be 3% ~ 5% of the journal.

(3) The surface roughness Rα of the inner circle is not more than 3.2 microns. ..

2. Technical requirements for coupling assembly

(1) The axial key must be repaired, and its assembly quality requirements are the same as those of Ping Jian flange detachable coupling.

(2) The thrust ring of the jacketed coupling should be repaired, so that its inner ring is closely matched with the shaft groove, and the contact area should be above 60%. 0.05 mm thickness gauge should not be inserted into the joint of shaft groove or shell groove on both sides.

(3) After assembly, a gap of 0.2 ~ 0.4 mm is allowed between the outer circle of the thrust ring and the inner hole of the jacket. Chapter IV Assembly and Installation of Propeller

learning target

Knowledge target

1. Learn the machining method of propeller;

2. Learn the assembly method of propeller;

3. Learn how to install the propeller.

capability goal

1. Propeller can be processed;

2. The propeller can be assembled;

3. Propeller can be installed.

Section 1 Processing and Assembly of Propeller

First, the general situation of propeller

1. Basic concepts

Propeller is the most common ship propulsion device, generally with 3 ~ 6 blades. Most of the propeller blades are cast together with the propeller shell, but some of them are made detachable and fixed on the propeller shell with bolts, which is called combined propeller. Small and medium-sized ships usually have 3 ~ 4 blades, while large ships often have 4 ~ 5 blades. The function of propeller is to convert the power from the main engine of the ship into the thrust to promote the movement of the ship. Its processing and assembly quality directly affects the navigation performance and safety of ships. The correctness of propeller geometry is the main factor to ensure the quality, among which the diameter and pitch of propeller are particularly important.

Figure 4- 1 shows a three-blade propeller. The part connected with the stern shaft is called the propeller shell. Looking from the stern to the bow, the blade surface is called the pressure surface, which is a helicoid, and its reverse side is called the suction surface. The pressure surface is also called leaf surface, and the suction surface is also called leaf back; When the main engine rotates forward, the edge of the blade that enters the water first is called the leading edge, and the corresponding other edge on the same blade is called the trailing edge.

The farthest point from the propeller center to the blade edge is the radius, the diameter of the circle is called the propeller diameter, which is denoted by d, and the distance that any point on the blade surface rises around the propeller axis is called the propeller pitch H. Propeller can be divided into two types according to its pitch: fixed pitch propeller and variable pitch propeller. The former has the same pitch on all radius sections on its leaf surface, while the latter is not. In a certain radius range, the pitch often increases with the increase of radius. The efficiency of variable pitch propeller is high, but the manufacturing and processing of blades are more troublesome. In addition, there is an adjustable pitch propeller, whose blades are movably installed on the propeller shell and can be driven to rotate by an internal transmission mechanism, thus changing the pitch and speed.

From the tail to the head, when the front car rotates, the propeller rotates clockwise and counterclockwise. For a twin-screw propeller ship, turning forward is called an external propeller, and vice versa. Usually, a twin-screw propeller uses an external propeller to prevent floating objects in the water from being caught. Because the blade bears thrust, there must be a certain thickness between the blade surface and the blade back. There are two cross-sectional shapes of blades: wing shape and bow shape, as shown in Figure 4-5 (flattened cross-sectional shape). The distance b between the two ends of the section is called chord width, and the connecting line between the two ends is called chord line. The maximum thickness of the section is represented by t, the t of the bow section is at the midpoint (b/2) of the chord width, and the t of the wing section is about the distance for installing marine auxiliary machines and boilers in Chapter 5.

learning target

Knowledge target

1. Understand the general purpose and types of auxiliary machines;

2. Understand the uses and types of deck machinery;

3. Understand the purpose and type of boiler;

4. Describe the general installation process and matters needing attention of auxiliary machines and boilers on board.

Ability goal:

1. will carry out the installation process of general auxiliary machines on board;

2. Being able to install deck machinery on the ship;

3. Be able to install boilers on board;

4. Common adhesives will be coordinated and used.

Ship auxiliary machinery, that is, ship auxiliary power machinery, is a set of power equipment that provides energy for normal operation, operation, life and other needs of ships.

Section 1 Installation of General Auxiliary Machines on Board

There are many kinds of general auxiliary machines on board, such as marine pumps such as centrifugal pumps, screw pumps and jet pumps, marine air compressors, ventilators, marine refrigeration devices, marine air-conditioning devices, oil separators, marine anti-pollution devices and seawater desalination devices. The installation quality of these auxiliaries directly affects the normal operation of the ship in the event of shipwreck.

Firstly, the auxiliary machinery on board is transported to the ship for installation.

Modern ship auxiliaries are mainly transported to the ship for installation in two forms.

(1) Assemble the auxiliary machine into a unit. That is, the power part and the working part are installed on a base, such as 3S 100D screw pump (as shown in Figure 5- 1), or the power part is installed on a casing, such as 3LU45 screw pump (as shown in Figure 5-2); Wait a minute.

(2) Assemble the auxiliary machine into functional units. The DRY-5 oil separator shown in Figure 5-3 is an example. This form is more advanced than the previous one. When it is installed on a ship, just position and fasten it, and then connect the pipeline and power supply to use it. It is very convenient and has been used by some domestic shipyards with good results.

Compared with single mechanical ship installation, the above two forms have the following good economic and technical effects:

(1) Move most of the fitter's assembly work from the ship to the workshop, make full use of the equipment and favorable space conditions in the workshop, and improve the installation quality and labor productivity;

(2) Due to the finalized product supply or pre-assembly, only the whole set needs to be hoisted during shipbuilding, which can greatly shorten the shipbuilding cycle; 3) Because the auxiliary machine itself has a male base or shell, the machining requirements of the upper plane of the hull base combined with it are reduced, and even the gasket can not be scraped, which greatly reduces the heavy fitter's labor and facilitates the installation of the shock absorber (this is especially important for military products, because many auxiliary machines on board are installed on the shock absorber).

Second, the auxiliary installation related process projects

Preparation of 1. pedestal

Auxiliary machines are generally installed on the deck or the base of the hull through gaskets or shock absorbers. There is no need to process the deck support part, and the processing requirements for the base support surface are not high. Generally speaking, the requirements for ships are slightly higher than those for civilian ships. The requirements for the substrate are as follows:

(1) The roughness of the bottom plate shall not be greater than 3mm in the length of 1m, but shall not exceed 6 mm in the whole length or width;

(2) The length and width tolerance of the foundation panel is+10 ~-5 mm;

(3) When checking the diagonal lines on the bottom plate, the two diagonal lines should intersect, and the degree of non-intersection should meet the following requirements: length