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Common problems and solutions of vertical round sponge
Time:2020/5/28 13:52:27    

Some abnormal phenomena often occur during the operation of the vertical foaming machine, timely measures should be taken to solve it in order to maintain normal production. Among the most commonly encountered are the following

(1) The foam "tightens" or shrinks: when the foam rises to the highest point during foaming, the cell breaks and there is a phenomenon of foam spouting which is normal. If this is not the case, the foam will "tighten" or close the cells. The main reason is the excessive amount of tin catalyst and the fast pore wall of the gel is strong; Or there are too many foam stabilizers, and the cells are too stable to blow, resulting in large closed cells.

(2) Foam rupture: The main reason is that the operation formula is wrong and the calculation pumps have errors, resulting in inaccurate formulas and runaway. Insufficient tin catalyst and foam stabilizer or decreased activity are the main reasons for foam burst. Other mechanical factors can also cause the foam to burst, such as excessively fine cells, foreign impurities, oil stains, uneven or fluctuating conveyor belt speed, and inappropriate shape and size of polyethylene bags, which can cause bursting of the foam.

(3) Foam slip: This happens when the needle plate conveyor belt cannot catch the foam, usually when the "starting ring" is removed. The bubble stops rising or even falls and marks can be seen on the surface of the bubble. The reasons are too long rise time, too low temperature in the aging section, the foam does not fill the entire section, the foam closed cell height is high, "tight", the conveyor belt speed is too fast or the installation is not suitable will cause the foam to slide down.

(4) Compression line: It means that there is a clear white interface in the foam block, and a white line clearly appears on the cut cross section.The foam strength on the white line is very poor and it is a substandard product. This white line is called a compression line. This happens when the speed of the conveyor belt is too slow, or reduce the discharge volume to keep the speed of the conveyor belt constant, or gradually increase the speed of the conveyor belt to exclude this compression line. The way to eliminate the compression line is to estimate how far the foam enters into the maturation section when it is fully raised. If it is fully raised as soon as it enters into the curing section, it is best to increase the speed of the conveyor belt only; If it has already entered into the aging section when it is fully raised, it is better to reduce the discharge volume and keep the conveyor belt speed unchanged. There are many reasons for the defects in the foaming process of the lump foam, including chemical and mechanical factors. The foam defects, the main reasons and the treatment methods in the foaming process are as follows:

1. Foam cracking - The foaming rate exceeds the gelation rate in the late stage of foaming, which can increase the amount of tin catalyst and accelerate the gelation rate;

2. Horizontal cracking in the middle of the foam - Uneven material distribution causes part of the material to overlap, the material liquid can be reasonably distributed, and the paper mold to be transmitted should be straight;

3. The lateral cracking of the foam surface - The speed of the conveyor belt is not suitable, which causes the whitening area to be narrow and the material overlap is serious. It is necessary to pay attention to the whitening situation and adjust the speed of the conveyor belt appropriately;

4. Longitudinal cracking inside the foam

① The rate of the foam is different before and after, which causes the foam to twist scraps, so the foam travel rate can be adjusted to make it consistent;

② Leakage in the amine catalyst pipeline causes excessive local catalyst in the foam. Need to check the material pipeline frequently to prevent leakage;

5. Foam shrinkage and closed cells occur simultaneously

①The stirring speed is too low, needs to be increased;

②Too much tin catalyst which needs to be reduced;

③ The amount of added in the air is too less (especially when the temperature of the material is low), it is necessary to increase the air flow to increase the opening rate;

6. Stripes

① The whitening of the material is too fast, should find the reason for the premature whitening (such as too much catalyst, too high temperature, etc.) and the problem; in addition, increase the white area to make the unreacted materials partially overlap;

②The materials are mixed unevenly, so the conveyor speed can be adjusted properly, the stirring speed can be increased and the installation of the mixing head can be checked;

7. Big stomata

① The mixing effect is not good, the air can not be evenly dispersed, we can improve the mixing effect of the mixing head, increase the mixing speed;

② Pigment precipitation - We can increase the ball milling time of the pigment liquid;

③The discharge speed is too fast, the impact force is too large, air bubbles are mixed in it, We can adjust mixing head speed and acute angle size;

8. The foam cannot be formed

① The temperature of the material is too low (below 16 ℃), we can raise it by above 20 ℃;

②The catalyst is invalid, you can check the activity of the catalyst;

③The quality of polyether is unqualified. If the acidity is too high, the adjustable formula is still not resolved, should stop and check.

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