The reinforcement of the board can be divided into two methods: the “back mesh” reinforcement on the back of the board, and the penetration reinforcement on the surface of the board.
01. Reinforcement of “Back Mesh”
Back mesh reinforcement refers to the use of high-strength fibers to protect the mesh holes, with a mesh size of generally 5 × 5mm, bonded to the back of the board through epoxy resin, and dried to enhance the strength of the board. The width of the entire roll of fiber protection net is divided into different specifications from 1.2-1.8m, and the weight is generally about 900g/m2. According to the actual needs of the board, the “back mesh” reinforcement process can be used to reinforce various types of large and thin boards that need reinforcement, such as marble, granite, and limestone.
The solidification time is an important process parameter for reinforcing the back mesh plate, which depends on factors such as the quantity and output of the plate that needs to be reinforced with the back mesh, the operation method of the back mesh process, and whether to choose a drying furnace or the drying capacity of the drying furnace. If there are a large number of boards that need to be reinforced in the production line and the production requirements are high, mechanized back mesh reinforcement can be used, and the natural full curing method at room temperature or a drying furnace with flat curing heating can be selected. If the production requirements are high, vertical drying furnaces can even be chosen. For some production lines with small reinforcement and low production capacity, manual back mesh operation can be used, and the natural and complete curing method at room temperature can be used.
02. Surface penetration reinforcement
Some stone surfaces have many micro cracks, and some micro cracks even penetrate deep into the board. Although reinforced, their strength still cannot meet the requirements of grinding and polishing or the requirements of finished boards. At this point, it is necessary to choose to perform penetration reinforcement treatment on the surface. The front penetration reinforcement process includes penetrating the highly permeable epoxy resin AB adhesive solution into the gaps on the surface of the board, drying it, and then grinding and polishing it.
Epoxy resin AB adhesive for surface penetration reinforcement is used as an example to illustrate. The solidification temperature of this adhesive is also 25 ℃, with a minimum curing temperature of 10-15 ℃ and a curing time of 4-6 hours at room temperature. In stone production lines equipped with automatic repair and drying units, all drying equipment uses a flat horizontal drying furnace or a vertical vertical drying furnace to perform high-temperature curing treatment on the surface penetration reinforced board, To accelerate the complete curing of the adhesive. For some simple stone production lines with low production requirements, natural curing at room temperature can be used, but it is best to cure for 24 hours before proceeding to the next process.
Due to the wide variety and varying shades of stone materials, as well as the fact that surface penetration reinforcement treatment is carried out on the surface of the board, when selecting high-strength penetrating adhesive for surface penetration treatment of the board, it is necessary to consider whether its color is the same as the color of the board or can be reasonably matched. After reinforcement treatment, there should be no traces of high-strength penetrating adhesive. Here, it is necessary to color adjust the high-strength penetrating adhesive, At this point, it is best to choose epoxy color paste or color paste to avoid affecting the curing and usability of the adhesive.
Natural decorative stone is mined from mines as raw materials, sawn and cut into rough boards in stone processing plants, and then ground, polished, and cut. About 30% of the structure of stone waste materials is loose and porous, with wide and deep cracks. During the transportation of waste materials, especially when sawn into rough boards, they are easily broken into waste stones, causing huge waste of natural resources and causing significant economic losses to stone enterprises.
Insiders have explored and practiced many methods on how to reinforce waste materials and ensure the sawn yield. There are currently two conventional methods in the market: manual pouring and external wrapping. For raw materials with obvious holes and large cracks, manufacturers mostly use simple equipment such as syringes or grease guns to inject glue into them, so that they can solidify and have a certain adhesive strengthening effect. Although the process operation is simple, it has the disadvantages of low efficiency and easy leakage and waste of glue. More importantly, the penetration depth of glue into cracks is limited, and the internal reinforcement effect of the waste material is not satisfactory. There is also a mainstream reinforcement method in the current market – external wrapping. Adopting glass fiber reinforced material and polymer adhesive material for bonding, the external reinforcement of the four cut sides of the raw material is carried out.
By wrapping and strengthening around the edges, it is possible to basically prevent missing edges and corners during the sawing process of the raw material. However, the reinforcement effect on the internal parts of the raw material, especially those with developed internal cracks, is minimal. During the sawing process, the strong back and forth vibration of the saw blade can cause the originally loose and cracked internal stones to fall off, resulting in jamming or even collapse, seriously affecting normal production.