1, longitudinal oiling slideway launching is a launching facility integrating slideway and slideway, with a long history and durability.
When launching, first pour a certain thickness of grease on the slideway to reduce friction. This kind of grease used to be butter, but now it is made up of paraffin, stearic acid and rosin in different proportions. Then the keel pier, the side pier and the bracket are all removed, so that the weight of the ship moves to the slideway and the skateboard, and then the anti-skid device is released, so that the ship slides into the water along the slideway together with the bracket and the skateboard, and floats on the water by its own buoyancy, thus completing the launching of the ship. This launching method is suitable for ships with different launching weights and ship types, and has the advantages of simple equipment, low construction cost and convenient maintenance and management. But it also has some disadvantages: the launching process is complicated; The spilled oil is greatly influenced by the ambient temperature, which will pollute the waters; When a ship floats at the stern, it will produce great bow pressure, so some ships equipped with bulbous bow and bow sonar cover have to strengthen the bulbous bow or temporarily not install it until it is launched and then installed in the dock. The travel of the ship in the water is long, so the width of the water area is generally required to be several times the total length of the ship to be launched. When necessary, an anchoring device or steering device should be installed on the ship to be launched, and the launching stroke can be controlled by towing the anchor or steering after full floating.
2, longitudinal steel ball slideway launching
In this way, a steel ball with a certain diameter is used instead of grease as an antifriction device, which changes the original sliding friction into rolling friction and reduces the friction resistance between the skateboard and the slideway. Steel balls can be reused and have good economy. The steel ball slideway launcher is mainly composed of high-strength steel balls, distance protectors and track plates. The rangefinder is equipped with 12 steel balls per square meter. There is a layer of rail plate on the wooden skateboard and slideway to prevent being crushed by steel balls, and there is a steel ball net bag at the end of slideway to receive falling steel balls and distance protectors. This launching method has the advantages of quick start, small slope of slideway and skateboarding.
The width of the channel is also small, the steel ball can be recycled, and the installation cost and use cost of the launcher are lower than those of grease. And it is not affected by climate, so the launching calculation is more accurate. However, the initial investment is large, the skateboard is heavy and the vibration is great.
3, horizontal oiled slide into the water
This mode means that the launching of the ship glides in the width direction of the ship, not the stern, but the side of the ship enters the water first. This method can be divided into two types. One is that the slideway extends into the water. First, the boat is towed to the wedge-shaped skateboard and then slid into the water along the slideway. The other is that the end of the slideway is interrupted at the vertical shore wall, and when the ship is launched, it falls into the water together with the launching frame and skateboard, and then the buoyancy and stability of the ship tend to balance and float fully. The falling height of the ship is 1-3 meters. This method is easy to cause launching accidents, because there are many slides used at the same time, and the falling launching boat rolls violently, which requires high lateral strength and stability.
2. Floating launching Floating launching is a launching method in which water is pumped or flowed into the pit of shipbuilding, and the ship floats by its own buoyancy. The most common thing is to build a dock and launch it.
There are two kinds of docks used in floating launching, namely dock construction and dock repair. The difference is that the dock building is wider and shallower, while the dock repair is deeper.
Dock building is a kind of hydraulic building used for shipbuilding and launching. There are many forms, such as single door, double door, mother-child dock and so on. The foundation structure consists of dock floor, dock wall, dock door and pump room. The dock door itself has a ballast tank and a water inlet and outlet system. After it is installed in place, the water pressure will be input into the dock door water tank, and the dock door will sink into place, and it will be tightly pressed against the dock door under the pressure of seawater outside the dock, and then the water in the dock will be drained, so that the ship can be built in the dock.
After the ship is built, the water in the waters outside the dock is introduced into the dock through the water intake and drainage system, and the ship floats by buoyancy. When the water level in the dock is the same as that outside the dock, the ballast water in the dock door can be discharged, the dock door can be unloaded, and then the ship can be dragged out of the dock door by tugboat, and the dock door can be reset to enter the next round of shipbuilding.
Dock launching is a simple launching method with better safety and process simplicity. It can effectively overcome the shortcoming of excessive elevation of the head of the inclined slipway, reduce the lifting height of the crane, avoid the water width required for gravity launching, and introduce mechanized construction means. Therefore, although the shipyard has a large initial investment, it is still the only means to build VLCC.
Third, mechanized launch.
1. Mechanized launching of longitudinal ship row slideway
A launching method is to build a ship on an integral row or a segmented row with rollers. When launching, a winch is used to pull the row to send the ship into the water along the track on an inclined berth, so that the ship floats completely. The length of each section of the segmented raft is 3-4m, the width is 80% of the width of the backbone product, and the height is 0.4-0.8m.. Because the row at the bow has to bear a lot of head pressure, it is necessary to strengthen its structure, so
It is divided into two types: the first boat row and the ordinary boat row. Because the top surface of the boat row is parallel to the slideway, the height is only 0.4-0.8m, the underwater part of the slideway is short, and the water depth at the end of the slideway is small. With the flexible connected segmented boat row, the boat row can be close to the end of the slideway after floating, and the length of the underwater part of the slideway and the water depth at the end can be further reduced. This kind of slipway has low technical requirements, simple hydraulic construction, small investment and stable and safe launching operation, and is mainly suitable for small shipyards. However, due to the small height of the raft, the bottom operation is very inconvenient, and it is only suitable for launching operations of small ships at one time.
In order to improve the utilization rate of the slipway, transverse pits can be set, and the combination of multi-position horizontal slipway and longitudinal inclined slipway can greatly improve the utilization rate of the longitudinal slipway.
2. Mechanized push-out of longitudinal slideways at two supporting points
This kind of launching uses two independent launching vehicles to support the launching boat, which can be directly said to be dragging the boat from the horizontal slipway to the inclined slideway for launching.
This kind of slipway connects the horizontal slipway and the inclined slipway with an arc, which makes the ship move smoothly. Its advantages are simple structure, convenient construction and easy operation, but its disadvantages are that only two launch vehicles support the fore and aft of the ship, which requires high longitudinal strength of the ship and will produce great head pressure when the stern floats, so it is only suitable for ships with high longitudinal strength.
3. The wedge-shaped launch vehicle is launched longitudinally and mechanically.
The launching frame on this slide is horizontal or slightly inclined, and the ship floats horizontally when it is launched, without generating head pressure. The launching process is simple and reliable, and it is suitable for launching larger ships. Connecting it with multi-position horizontal slideway with transverse pit can improve the use efficiency of slideway, and it is an ideal longitudinal mechanized launching facility. The disadvantage is that the tail end of the launch vehicle is too high, which requires a large water depth at the end of the slide, resulting in a large amount of hydraulic construction and large investment, and the end of the slide is easily covered with silt, so the hydrological conditions should be fully considered when selecting.
4. Mechanized push-out of longitudinal slideway in slope change zone.
The lateral movement area of this launching mode consists of two parts: horizontal section and variable slope section. The transverse wing is equipped with a transverse moving area with multi-position horizontal berths. Because of the need of moving ships, the track of the transverse moving car is in a horizontal state, so it is called a horizontal section. Only one group of tracks in the variable slope traverse area is still horizontal, and all other groups have slopes. The slopes of these tracks can make the traversing vehicles gradually change their longitudinal slopes in the process of traversing, and finally get the same slope as the longitudinal sliding, so it is called variable slope section. At the same time, in order to keep the horizontal car level in the variable slope section, the track with slope adopts the method of high and low stratification.
Because the transverse moving area has the function of changing slope, the longitudinal inclined slideway is used for launching. At the same time, a longitudinal inclined chute can be built at the longitudinal axis of the launching chute. The traversing car realizes the connection with the horizontal slideway in the horizontal section; At the end of the variable slope section, a longitudinal inclined chute and a launching chute can be connected, so that one launching facility can be used for two kinds of chutes. Moreover, this kind of slide is composed of slide trolley and launching pulley, so the water depth at the end of the slide is small and the investment in slide construction is small.
However, this launching method, like all slides with longitudinal launching technology, has a high head pressure when the ship floats.
Generally, this method is mostly used in fishing boat repair shops and small and medium-sized shipyards with tight coastline and vast hinterland in China. Shipbuilding repair can be carried out on the horizontal slipway in the infield, and only one launching slipway is set to reduce the maintenance workload of the underwater part of the slipway.
This launching method can manually control the speed of the trolley carrying the ship to be launched, and can stop launching if necessary. It can also be used to repair the upper row of ships.
5. Mechanized launching of high-low rail transverse slideway
This slide consists of two parts: the slope part of the slide and the lateral moving area. When the launch vehicle runs on the slope of the slideway, the wheels at the adjacent water end and the berthing end walk on two tracks with different heights, so as to keep the launch vehicle frame in a horizontal state. For this reason, the high rail in the slope part and the corresponding rail in the lateral moving area should be smoothly connected by an arc with the same radius. The height difference between high rail 1 and low rail 2 shall ensure that the axes of adjacent water ends and shore ends are on the same horizontal plane. The horizontal distance between any two points on the transition curve should always be equal to the wheelbase of the wheel, so that the launch vehicle can remain horizontal at any position when sliding down. This method has the advantages of simple layout, low shelf surface and no deep ditch when the slope part is stressed. At the same time, multiple lateral berths can be arranged on the lateral wing of the lateral moving area, which has high mechanization degree and simple and reliable operation. The requirements for the width and depth of water area are far less than those for longitudinal launch, and the maximum launch weight is 5000 tons. However, this method is complicated in hydraulic construction, high in track laying accuracy and high in cost.
6. Mechanized launching of comb slideway
It consists of a slope slideway and a horizontal lateral moving area, and the lateral wing of the lateral moving area is connected with a multi-station horizontal slideway, and the slideway trolley and the launching vehicle are used separately.
Multiple groups of tracks are laid on the ramp, and each group of tracks has a single-layer wedge-shaped launch vehicle, and each launch vehicle is controlled by a separate electric winch. The track of the ramp and the crossing area is staggered, and the connecting line of the track staggered area at the same level is called the O-axis. The horizontal track and the slope slideway extend across the O-axis for a certain length, forming staggered comb teeth, so it is called comb tooth slideway, and its function is to transfer the ship to be launched on the horizontal platform to the wedge launch vehicle.
In specific operation, put the boat on the slipway trolley and start the slipway trolley to move longitudinally. When the ship moves to the intersection of the longitudinal track and the transverse track in the transverse moving area, the hydraulic lifting device at the lower part of the car is started to lift the wheels of the slipway car. After the frame rotates 90 degrees, it falls on the transverse moving track. Start the slipway car to move the ship to the O axis, and then start the lifting device on the slipway car again to slightly lift the ship. At this time, the wedge-shaped launch vehicle is supported by the electric trolley, the lifting device of the slipway trolley descends, the slipway trolley is removed, and the ship is located on the launch vehicle. Finally, the electric winch on the launch vehicle is started to send the ship into the water to complete the launch operation.
The trolley and launching vehicle have independent electric winches, which avoids the trouble of replacing steel wire and improves the safety and efficiency of operation; The launching wheel is depressed, so the construction accuracy of the slope slide is low; Each area has strong construction independence and can be constructed by stages. However, due to the self-provided traction equipment, the structure of the ship trolley is complicated and the maintenance is cumbersome; It is troublesome to change the wheels and O-axis of the transshipment trolley, so the shipyard doesn't use it much.
7, ship lift into the water
Ship lift is a large platform built on the shore wall to carry ships, and it is a launching facility that uses windlass to lift vertically. According to the relative position of the platform and the ship's trajectory, it can be divided into vertical and horizontal.
When the ship is launched, the winch is driven to align the platform of the ship lift with the movement track of the ship and fix it with positioning equipment. Move the boat to the platform under the load of the boat moving car, take all kinds of cables and dismantle the positioning equipment. The winch lowers the ship lift platform together with the launched ship into the water, and the ship will float by itself under the buoyancy.
The ship lift has compact structure and small floor space, and is suitable for narrow factory areas and steep shore walls. Shipyards with limited waters have stable operation and high efficiency, which are suitable for mass production of leading products. However, the ship lift has a large limitation on the size of the ship and is only suitable for small and medium-sized shipyards. Shanghai 4805 Factory (Shenjia Shipyard) has the first 3000-ton ship lift in China.
Floating docks are used for launching operations. Firstly, locate the floating dock, align the track on the dock floor with the track of the horizontal berth on the shore, move the ship carried by the berth trolley into the floating dock, and then disconnect the floating dock from the shore wall. If the water depth under the dock is enough, the ship can float out of the dock. If the water depth under the wharf is insufficient, the floating dock will be towed to a specially built sinkhole for sinking.
According to the docking mode of the ship, it can be divided into longitudinal moving type and lateral moving type. The center line of the vertical floating dock is parallel to the ship's trajectory of the horizontal berth, and a double-wall floating dock can be used, and the ship moves in the direction of the captain when docked. This floating dock is used in Jiangnan, Shanghai and Huangpu, Guangzhou. The transverse floating dock can adopt single-wall floating dock or double-wall floating dock. However, one side of the floating dock can be removed. When in use, the floating dock will lean against the shore wall of the horizontal berth, the dock wall on the shore side will be removed by crane, the ship will be towed into the floating dock, and then the movable dock wall will be reassembled for launching operation.
Floating dock launching facilities have the ability to dock with multi-position horizontal berths, with low cost, short construction period and stable and safe launching operation, but the operation is complicated, and deep-water docking pits are needed in most cases. 4. Balloon launching At present, small and medium-sized shipbuilding enterprises in China generally adopt balloon launching. Although it has the advantages of economy and convenience, compared with traditional launching methods such as slideway launching, track launching and dock launching, there are still some problems such as insufficient theoretical support and irregular actual operation. According to the existing practical experience of ship construction, it is basically feasible to use the airbag launching method when building a steel ordinary ship with a length less than180 m. Therefore, it is stipulated in the standard that the first-class and second-class shipbuilding plants are allowed to use the airbag launching method, and corresponding requirements are put forward for the facilities and equipment for launching the airbag.