What details should be paid attention to in the model design of refractory bricks

(1) Scale rate. The external dimensions of refractory products must meet the specified requirements, and the volume of the bricks will change during the drying and firing of refractory bricks, especially during the firing process. General products shrink, while silica bricks expand due to polycrystalline transformation. Therefore, the scale must be considered when designing the press model to ensure the correctness of the product size. In actual production, the brick mold size is usually calculated as follows.

For products that shrink during firing: brick mold size = finished product size + finished product size × scaling rate

For products that expand when refractory bricks are fired: brick mold size = finished product size-finished product size × scale rate is generally determined through actual tests based on different brick types and clay materials. At present, when producing silica bricks in my country, the scale reduction rate is generally 2~3%; the scale reduction rate of clay bricks is 1~2%.

When calculating the size of the brick mold, it should be noted that the compression (or expansion) values of the kiln when the brick is fired are different in the compression direction and the non-compression direction, so the same piece of product should be specified according to the compression and non-compression conditions during firing. Different zoom ratios. For products that shrink during firing, the scaling ratio in the compression direction should be larger, usually 0.5 to 1% higher than that in the non-compression direction; while for products that expand during firing, the scaling ratio in the compression direction should be Smaller.

(2) The refractory brick formwork should be installed with a taper, with a small lower mouth, a large upper mouth, and symmetry, and the product size must be qualified. The taper of the model after installation is generally five thousandths. Some bricks require small dimensional tolerances, and the template can also be installed without taper, which can be solved by moving the template. The taper is designed on the outer side of the inner template, and the blank is ejected together with the inner mold when it is ejected, and the outer template is fixed.

(3) The surface of the template must be smooth, smooth, and have high hardness.

(4) Make the largest area of the product as the pressure surface as far as possible.

(5) The groove edges in the refractory brick model have arcs, and the dead corners of the template have 1～2mm arcs.

(6) There is a protruding part at the bottom of the mold, try to make it into a movable wedge.

(7) The uneven surface should be made into a live bottom.

(8) For products with a thickness of more than 150mm, pressure on both sides should be considered.