Brick press process principle

Brick press process principle

1. Molding process principle 1. The process of filling the powder with a certain moisture and gradation into a cavity with a certain shape and volume and applying a certain pressure to make it a fixed-shaped object is called the brick press molding process principle. .

1 mezzanine

1 Partial interlayer (stratification)

A Local interlayer refers to the existence of pieces of interlayer at the corners or in the middle of the bricks.

B The cause is that the moisture content of the powder is extremely uneven, there are overdried lumps in the powder, the size deviation on both sides of the mold is too large, the powder rack, powder frame, silo, and hopper have not been cleaned for a long time, and the side plates of the mold are too severely worn. It is caused by the poor pressure equalization effect of the mold or the bulging of the mold surface. There are two situations here, one is caused by poor exhaust, and the other is the introduction of overdried hard lumps into the powder.

C The solution is to extend the aging time of the powder, add a vibrating screen at the silo entrance or conveyor line, thoroughly clean the powder frame, silo, hopper, etc., and check the height error of the mold frame platform, the height error of the lower mold core, and the beam Height error, check the wear degree of the side plate, check the oil pressure of the upper mold core, and the wear degree of the upper mold core. Generally, the height error of the mold frame and the lower mold core is within 0.15mm. The wear of the side plate is measured near the demoulding step. The wear and tear condition and whether there are any excessively worn parts. Check whether the oil pressure of the mold meets the requirements, whether the protrusions on the surface of the mold are uniform, whether the mold is excessively worn, etc.

2 heavy leather

A Heavy skin refers to the problem of delamination on the entire cross-section of the brick. It is generally divided into upper and lower layers, one is very thin and the other is very thick.

B The reason for the occurrence of heavy skin is that the moisture content of the powder is too large, the stamping speed is too fast, the pressure at one time is too high, the aging time of the powder is not enough, the gap of the mold is too small, and the exhaust control time is too short.

C The solution is to control the moisture content of the powder within the range required by the press, extend the aging time, adjust the stamping speed, reduce the primary pressure, increase the mold gap, and extend the exhaust control time. The main problem here is poor exhaust. caused.

3 Thousand Layer Pancakes

A Thousand-layer cake refers to pressed bricks that are divided into many layers, even small pieces.

The causes of B are that the moisture of the powder is too dry, the exhaust control time is too short, the aging time of the powder is too short, the gap of the mold is too small, the stamping speed is too slow, etc. This defect is mainly caused by poor exhaust.

C The solution is to actually measure the moisture of the powder, eliminate the cause of moisture, extend the aging time, reduce the falling speed and pressurization speed of the beam, extend the exhaust control time, and increase the mold gap.

Two deformations

1 Local deformation

A. Local deformation refers to local unevenness and local concave and convex in the plane of the product. This defect is common to all wall and floor tiles, but the degree is different.

B The reason for the deformation is that the density of the brick is different, and the shrinkage of each part during firing is inconsistent, causing stress inside the brick. The stress is not completely eliminated before cooling (except for the kiln reason), and the local pressure caused by the press The deformation is due to relatively high protrusions on the surface of the mold, poor equalization effect, unreasonable adjustment of the mold, deformation of the mold itself, partial degumming of the upper mold, poor mold manufacturing accuracy, large difference in brick thickness, and extremely uneven feeding. , There are overly wet mud balls in the powder, etc.

C The solution is to correct the mold defects, restore regular adjustments, check whether the powder is too dry or too wet, and adjust the feeding mechanism to improve feeding uniformity.

2 checkerboard tiles

A Checkerboard tiles are deformed like a checkerboard on the front of the product. Sometimes they are not easily visible from the front and can only be seen from the side against the light.

B This kind of defect is generally caused by the formula or the upper mold core of the equalizing pressure mold. The pressure of the mold on the green body is not uniform. If the firing range of the formula is too narrow or the equalizing pressure effect of the mold is too poor, it will Causes defects in checkerboard tiles.

C The radical method is to adjust the firing range of the formula, increase the aluminum content, reduce the sodium content, select a mold with good equalizing pressure effect, and stabilize the atmosphere and temperature of the kiln. This defect is relatively rare in ordinary steel molds or rubber molds. few.

Three cracks

1 straight crack

A Straight crack refers to a crack extending from the edge of the brick to the middle of the brick. In severe cases, the brick is divided into two halves or more pieces.

B This kind of defect is caused by the impact of the brick. Whether it is in the press or on the conveyor line, it may cause this defect. There are two reasons for this defect in molding: First, the synchronization of the press ejection system and the beam The problem is that the beam rises too fast at the end of pressing, which lifts up the brick and causes it to fall, which can easily cause cracks. In addition, the impact speed of the brick pusher is too fast or the vibration is too large when pushing bricks, causing cracks.

C The solution is to adjust the coordination speed of the cross beam and ejection to synchronize them; reduce the impact speed and vibration of the billet pusher. If these two reasons are eliminated, the crack is caused by transportation and drying problems.

2 Expansion cracks

A ring split

① Ring cracks are ring-shaped cracks that exist around the brick. Generally, these cracks are distributed on the surface of the brick and are 1-2mm deep. They are not easy to observe before firing. Sometimes they can be seen with kerosene after drying.

② This defect is caused by excessive expansion of the brick in the mold. If it occurs occasionally, it is caused by changes in raw materials or formula changes; if not, it is caused by improper ejection speed or ejection delay of the press; or Caused by the draft angle of the side panel being too small.