The natural veneer stone is mined from the mine and cut into a wool board in a stone processing factory, which is then ground, polished and cut. About 30% of the stone blocks are loose and porous, and the cracks are wide and deep. During the transportation of the blocks, especially in the process of sawing into the board, they are easily broken into waste rocks, causing huge waste of natural resources. Caused major economic losses.
The industry has explored and practiced many methods on how to reinforce the blocks and ensure the rate of sawing. There are currently two more conventional methods on the market: manual infusion and external wrapping. For the blockages with obvious holes and large cracks, most of the manufacturers use simple equipment such as syringes or grease guns to inject the glue into it, so that it can be cured to a certain degree of adhesion. Although the process operation is simple, there are disadvantages of low efficiency, easy leakage of glue, and more importantly, the penetration depth of the glue to the crack is limited, and the internal reinforcement effect of the block material is not satisfactory.
There is also a way to strengthen the mainstream of the market - external parcels. The glass fiber reinforced material is adhered to the polymer adhesive material (epoxy resin or unsaturated polyester resin), and the material is cut smoothly.
The exterior of the face is reinforced. Through the surrounding package reinforcement, it can basically prevent the corners from falling off during the sawing process, but for the inside of the block, especially the cracks developed by the internal cracks have little effect, due to the strong saw blade during the sawing process. Shaking back and forth will cause the inner rock that was originally loosely cracked to fall, causing the card saw or even collapse, which seriously affects normal production.
It is understood that there is also a process of vacuum impregnation to strengthen blocks. The process immerses the whole material to be reinforced in a cylinder filled with glue, and simultaneously puts the cylinder with the waste material in a vacuum tank, performs a vacuum operation to allow the glue to fully penetrate into the inside of the block, and then heats the block. After curing, it has a good reinforcement effect on the blocks from the inside to the outside. However, the process operation requires large special equipment to assist, the efficiency is low, the glue requirement is high and the waste is large, the cost is difficult to control, and only a few varieties of blocks are applicable, so it has not been widely promoted. Now introduce a new technology to everyone.
1 high pressure perfusion
As the name implies, high-pressure perfusion is a process in which special glue is used to inject the inside of the block with pressurized equipment, and it is used as a process to reinforce the blocks. The process seals the cracks of the blocks, selects the appropriate glue injection points, and uses special equipment with a pressure of up to 30kg to ensure that the whole pouring process is controllable and the crack filling rate is high, thereby ensuring that the blocks can be reinforced and smoothly sawed.
The main equipment for high pressure infusion is high pressure perfusion machine and air compressor. The main materials are injection nozzle, crack sealant, block glue, cleaning agent.
2 high pressure infusion process
2.1 block pretreatment
Most of the surface of the block is adhered with mud. In particular, the slurry left by the wire saw is filled in the cracks and grooves. These impurities will affect the flow of the subsequent glue in the crack, so cleaning is required. The above parts were thoroughly rinsed with a high pressure water jet so that the cracks were fully exposed for subsequent operation. After the rinsing is finished, the blocks are allowed to dry naturally under the rain-proof conditions (no visible water can be observed by the naked eye).
2.2 crack seal
After the blocks are dried, the operator observes and analyzes the cracks in the blocks, and uses a stone cutter to place the cracked surface without cracks on the sleepers for operation. And use the marker to reserve the nozzle position mark on the other five faces. The position of the injection nozzle position should be subject to the following principles:
2.2.1 The installation distance of the same crack injection nozzle is 20-40cm;
2.2.2 The glue nozzle shall be installed at the crack bifurcation.
2.3 injection preparation
After the position of the injection nozzle is reserved, take a proper amount of sealant (AB component) and adjust it evenly according to the 1:1 mass ratio. Use a scraper to scrape the sealant into the crack outside the glue nozzle, and then along the crack 3 to 4 cm width. The area is thicker and thicker
The layer sealant (shown in Figure 1) ensures that the crack is completely sealed. Finally, the glue nozzle is installed in the reserved position with a sealant.
2.4 high pressure perfusion
After the crack surface seal and the injection nozzle are installed, it is allowed to stand at room temperature for 24 hours. After the capsule is fully cured, it can enter the high pressure infusion step. Firstly, the airtightness is detected, and the glue nozzle of the same crack is plugged with the matching plastic plug, and a compressed air interface is left at will, and the air compressor is started to pressurize the crack to 0.3 MPa to observe the crack leakage. If there is no air leak, the glue filling operation can be performed. If there is a leak, it is necessary to trap the leak point and wait for the sealant to fully cure. Therefore, the crack seal needs to be strictly and carefully operated so as not to affect the subsequent process and reduce the efficiency.
Connect the glue joint of the high-pressure glue filling machine to the glue injection nozzle, and tighten it tightly, open the high-position glue nozzle on the same crack and vent it, and mix the glue in proportion in the mixing container above the glue filling machine. all
Evenly, start the air compressor, open the air valve to inject high pressure into the glue, and when there is glue outside the high-position glue nozzle to be emptied, close the gas valve to stop the glue, and remove the high-pressure glue machine from the injection nozzle. Glue the joint and quickly seal it with the plastic plug to the vent. At this point, the crack has been fully glued, and it only needs to stand and fully cure. Repeat the above operation for other cracks.
2.5 operations, need to pay attention to:
2.5.1 When opening the gas valve, pay attention to the inlet pressure of the pressure gauge, the general operating pressure should not exceed 0.3MPa;
2.5.2 It is advisable to adjust the glue in the mixing container once to adjust the glue to 1-2kg. The room temperature (25 ° C) can be operated for 1H. In addition, if the glue is too much to operate, it may cause the phenomenon of rubber explosion, which may lead to abnormal conditions such as blockage of the gluer line;
2.5.3 After the completion of the filling, the appropriate amount of cleaning agent should be poured into the mixing container in time, the valve should be opened, and the glue connector should be placed in the mixing container to clean the equipment and pipeline to avoid residue. The glue cures the tubing and causes equipment failure.
2.6 high pressure infusion glue has the following characteristics:
2.6.1 Low viscosity: The mixing viscosity is only 120mpa·s. Under high pressure, the glue can penetrate into the tiny cracks inside the block;
2.6.2 Low temperature curing: It is also good in winter temperature only 5 °C
Curing
2.6.3 Moisture curing: The inside of the block material generally has a high water content, and the ordinary glue is easy to fail after entering the person, and does not play a good role in enhancing reinforcement. The molecular structure of the infusion gel contains a large amount of hydrophobic structure, which can fully infiltrate and completely solidify on the wet surface inside the block, so that the inside of the damaged block can be firmly bonded;
2.6.4 High strength: After testing, Kesheng stone block high pressure infusion glue is applied to wet stone - stone bonding, tensile shear strength is greater than 15MPa, higher than the corresponding national standards.
3 Conclusion
The high-pressure perfusion reinforcement is suitable for solving the problem of blockage damage caused by general transparent cracks, and has the characteristics of machine automation and constant pressure perfusion. The process has low labor intensity and low cost, and can achieve high efficiency and high efficiency. The technology has passed the technical appraisal organized by the Science and Technology Department of Hunan Province and has reached the international leading level.
At present, the technology has been promoted to the global market, and the domestic water head, Yunfu, Shanghai, Beijing stone market and foreign countries such as Turkey, Egypt, India and other countries have achieved unanimous praise. At present, there are over 500 pieces of high-pressure perfusion materials, and the yield rate is over 95%, involving multiple varieties, such as white magnolia, golden butterfly, and Altman. It has universal practical significance for the stone industry.
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