Anchor generally refers to a ship anchor and is the main component of the mooring equipment. An iron boat-stopping device, connected to the boat with an iron chain, and throwing the anchor to the bottom of the boat can make the boat stop.
Boating equipment, iron. One section is fixed on the boat with an iron chain, and the other end is barbed into claws, throwing it to the bottom or shore to stabilize the hull: anchoring. Anchor. Anchor chain.
There are many types of anchors, and high-grip anchors are commonly used in drilling platforms. The main feature of this anchor is that its holding force can only be guaranteed when the pulling force is horizontal. If the pulling force has a vertical component force and the holding force is reduced, the anchor claw will be pulled out of the soil. Experiments show that the grip force starts to decrease when the anchor shank rotates upward 6 °, and the grip force decreases significantly when the anchor shank rotates 12 °. Therefore, the lower end of the anchor chain must be tangent to the ocean floor when anchoring, otherwise there is a danger of anchoring. Anchor lifting is also taking advantage of this feature, pulling the anchor chain upwards to raise the anchor handle, the anchor loses its grip, and finally breaks through the ground.
The choice of anchor should consider the convenient operation, easy storage and economical applicability, but the most important thing is the grip of the anchor. The grip of the anchor is unknown on the one hand because of the different types of anchors, and it is related to the subsoil quality. As marine development advances to deep water, new requirements are placed on anchoring. In deep water, if the lower end of the anchor chain is still required to be tangent to the ocean floor to ensure the anchor’s grip, the required chain is very long. Therefore, it is necessary to study anchors that can withstand vertical component forces, such as using cement weights or anchor piles. When the rocky sea floor cannot be used for pile driving, bored anchor piles can be used. Some anchors are designed according to a specific seabed. If the anchor is used in a seabed that does not meet the design requirements, the anchor’s working performance is poor. Although there are formulas for calculating the holding force of various anchors of the holding anchor in different seabed conditions as shown in Figure 1, the true holding force of the anchor needs to be determined through field tests.
Modern anchors are made of cast steel or forged steel. There are four main types. ① Rod anchor: The anchor claw and the anchor stem are usually a whole, and there is a cross bar perpendicular to the plane of the anchor claw. Most rod anchors are double claws, and some are single claws. When used, one claw bites deep into the soil and has a large grip, but because of the crossbar, it is inconvenient to store and is mostly used for small ships. The main types of rod anchors are naval anchors (Figure 2), single-claw anchors (Figure 3), Foshan anchors, and Japanese anchors.
② Rodless anchors: The anchor claw and the anchor rod can be rotated relative to each other by a certain angle, and there is no crossbar. When used, the two anchor claws engage in the soil at the same time, which is convenient for anchoring and storage, and is the most widely used. Representative of the rodless anchors are Hall anchors (Figure 1) and their modified Spike anchors.
③ High-grasp anchor: The anchor claw is wide and can be rotated at a certain angle. The anchor head or the middle of the anchor claw has a protruding bar. Body, plays a stabilizing role. Because the anchor claw has a large soil area and large grip, it is suitable for sandy or soft soil. The main types of high-grip anchors are Danfoss anchors, Markov high-claw anchors, and speedboat anchors.
④Special anchors: the shape is different from general anchors, such as fungal anchors, the anchor head is fungal or umbrella-shaped, deep into the soil, large grip, difficult to move, mostly used for long-term anchoring, positioning, such as light boats, floats Anchors for ships, barges, etc.