Anchor bricks are also called hanging bricks. Anchor pieces and anchor bricks are novel and relate to traction bricks or tension bricks for industrial furnaces. Especially when it comes to the anchor bricks used in the industrial furnace roof in the forging industry. The neck part in the middle is where the hanging hook is installed. Make the hook into the shape of a "door" and then align it, clamp the middle of the anchor brick, and hang it on the I-beam. Another way is to anchor the brick with a hanging hole. There is a hole with a diameter of about 20mm at the top of the brick. Then the screw is made into an L shape, one end goes through the hole and then the nut is tightened, and the other end is hung on the I-beam to tighten the nut. In terms of the shape of the current industrial anchor bricks, there are many types, but the ultimate purpose is the same. That is to say, it will be used as the tensile support of the furnace top refractory castable to ensure the firmness and high-strength stability of large-area pouring.
 |
| Anchoring Bricks for the Furnace Roof |
Expansion joints for suspending and anchoring bricks on the furnace roof
The hanging distance of the anchor bricks in the furnace roof is 400~500mm, 500mm in the horizontal direction, and 400mm in the longitudinal direction. During construction, the inner surface of the castable and the top surface of the anchor brick should be kept on the same vertical plane as possible. The hanging size can also be properly adjusted according to the location of the gravity point. When the furnace roof is hung, it is mostly cast as a whole or rammed with refractory plastic. The form of furnace roof is divided into a flat roof and a vault. The vault is generally made of refractory castables, and the flat roof can be made of refractory plastic. No matter which pouring method is adopted, different expansion joints should be set for the anchor bricks, and they should not be directly dry poured without any expansion joints reserved. The raw materials used in the production of anchor bricks are generally products made of aluminum-silicon materials. At a certain temperature, SiO2 quartz residual crystals will expand to a certain extent. The common way to reserve expansion joints is to apply black asphalt paint on the outer surface of anchor bricks.
Common problems in the use of anchor bricks
The common problem of anchor bricks in use is fracture, and the cause of fracture is directly related to the stress in three aspects. The first is tensile strength, the second is compressive strength, and the third is shear stress. The most common is that in addition to the tensile stress caused by gravity, it also bears a large shear stress during use. Since there is a big difference in temperature between the part of the upper layer that is not embedded with castables and the buried part of the lower layer, the physical expansion after heating is also quite different. There will be a temperature difference in shear force between the layers in use, and the magnitude of the shear force is related to the expansion coefficient of the anchor brick after the temperature difference changes.
 |
| Suspending Anchoring Bricks on the Furnace Roof |
Considering the anchor brick from the aspect of production: one is the refractoriness, and the other is the tensile strength. Refractoriness is generally not a problem, the most important thing is the tensile strength. We are currently most concerned about the cold tensile strength of bricks. Because the weight of the entire furnace top is suspended at the neck of the upper part of the hanging brick, it is often at a low temperature here. Therefore, as long as the normal temperature strength of the brick is sufficient, no fracture will occur here, and if the normal temperature strength is insufficient, the so-called fracture will occur.
The material of the hanging brick and its strength characteristics at different temperatures, the strength of the sintered refractory product mainly comes from the ceramic bonding between the particles in the refractory material. The higher the degree of this ceramic junction, the higher its strength. The ceramic bonding of high alumina refractory products is mainly the result of liquid phase sintering, that is, the liquid phase is formed in the refractory material at a high temperature to promote the bonding and material migration between particles. The greater the amount of liquid phase formed. The better the sintering strength, the higher the strength in the cold state. However, cold strength and hot strength are often contradictory. Although a large amount of high-temperature liquid phase promotes sintering and high low-temperature strength, when used at high temperatures, this large amount of liquid phase will reappear, and the high-temperature strength will decrease. The higher the amount of high-temperature liquid phase, the lower the high-temperature strength.
