In the forming process of glass container, the drop forming is the first step of the bottle forming process, and it is also the key to the glass bottle forming process.
Drop forming is to make the drop glass liquid have a suitable and uniform temperature. Under the mechanical motion of the barrel, bowl, punch and scissors, the drop glass liquid forms to meet the requirements of forming.
The defect of glass containers (bottles and cans) "scissor print" is the obvious trace left on the bottles and cans due to poor shearing during the forming process of the material drop.
A kind of
1、 Shear process of droplet formation
The glass liquid flowing out of the bowl is cut by overlapping and closing the upper and lower scissor pieces to form the glass drop. In the process of shearing, the glass drops are impacted by the temperature of the scissors and the mechanical force of the scissors.
When the bad shear occurs, it is possible to produce glass shear marks on two parts of the material drop. The shear mark on the material drop will be left at the bottom of the glass bottle, and the shear mark under the material drop will be left at the mouth of the glass bottle. This kind of cutting trace will enlarge in the process of forming and blowing, forming a "scissors print".
"Scissor print" affects the appearance slightly, and becomes the source of crack.
A kind of
2、 The formation of scissor print
When the glass liquid flowing out of the bowl is cut off by the scissors, the glass liquid left in the upper part of the bowl mouth is suspended, and the glass liquid drop in the lower part falls into the mold through the guide material. When the suspension glass liquid and the lower glass drop which are cut off and left at the mouth of the bowl are cut, the scissors mark of the scissors will be left. Because of its large heat, the suspension glass liquid at the material bowl mouth can reduce the temperature difference through heavy heat and eliminate the scissor print generated by the upper scissor blade. However, because the lower glass droplet contacts with the mold and cools rapidly, it is easy to leave the scissor print generated by the lower scissor blade.
In the shear process of material drop formation, the glass liquid is cut through overlapping and closing of scissors. If:
1. If the sharpness of the scissors is not good, the cutting section of the glass liquid flowing out of the material bowl will be stuck, stretched or pushed in the horizontal direction of the upper and lower scissors. The glass liquid stretched or pushed by adhesion will cool faster than the whole material drop. In the conveying process of the material drop to the primary die through the guide chute, the glass liquid that is stuck, stretched or pushed by the heavy heat of the material drop during the shearing process may reach the same temperature as the whole material drop. It will not affect the whole material drop.
However, the effect of reheating is not good. The temperature of the glass liquid produced in the process of shearing may not be consistent with the temperature of the whole material drop, so the glass liquid produced in the process of shearing will form tiny bubbles in the material drop. The "scissor print" is formed during the molding and blowing process.
2. The amount of overlapping of the scissors is not enough, so that the scissors are not enough overlapped and closed, and the material drop is not completely cut when cutting the glass liquid. A glass drawing wire is formed between the hanging glass liquid and the shearing glass drops from the bowl mouth, which may cause tiny glass bulges at the upper and lower ends of the glass drops. The temperature of the glass bulge will drop rapidly, forming glass fragments attached to the surface of the glass drop, forming "scissors print" during the molding and blowing process.
A kind of
3. If the scissors are not tensioned enough, there will be a gap between the upper scissors and the lower scissors. When cutting the glass liquid, the cutting surface of the glass drops will be rough. If the roughness of the upper and lower cut surfaces cannot reach the same temperature with the whole material drop by reheating, a "scissor print" will be formed during the molding and blowing process.
A kind of
Under normal circumstances, the upper scissor blade is squeezed from the lower scissor blade, and the lower scissor blade is squeezed from the upper scissor blade. When the glass drops are cut off, the upper scissor and the lower scissor should be in a state of seamless overlap on the contact surface.
4. If the scissors are over tensioned, the squeezing pressure of the upper and lower scissors will become the resistance of each other's movement. This kind of resistance affects the amount of overlapping of the scissors, which makes the scissors not close enough and forms the glass drawing wire when cutting the glass liquid. In the process of forming and blowing, glass drawing will become "scissors printing".
5. The improper scissor cam makes the cutting action too slow. In the process of shearing, glass liquid is impacted by temperature and mechanical force of scissors. If the cutting action is too slow, more cutting marks will be left when cutting.
6. The cutting edge of the scissors should be sharp so that the glass liquid can be cut off easily. If the cutting edge of the scissors becomes blunt, the force of the blunt cutting edge on the surface of the liquid glass will increase when it is cut, and the cutting surface of the liquid glass will produce wrinkles. In the process of molding and blowing, the wrinkles on the cutting surface will become "scissors printing".
To ensure the sharpness of the scissors, the first is to timely replace the scissors; the second is to ensure good cooling in the production process.
7. Scissors spray too much or too little. In order to ensure the sharpness of the scissors, the temperature of the scissors must not be too high, so it is necessary to cool the cutting scissors, especially the cutting edge of the scissors.
Scissor water spray is the only way to cool scissor blade, but scissor water spray must be appropriate. Too small scissor water spray makes scissor blade not cool enough, and the blade of scissor blade becomes blunt, which will produce "scissor print". The scissors spray too much water, and the coolant is continuously sprayed on the glass liquid, causing the temperature of the glass liquid surface to drop, making the glass liquid shear badly, and also producing "scissors print".
The water spray of scissors can not only cool the scissors, but also lubricate the mutual movement of the upper and lower scissors