With the increase of beer production in China, the demand for beer bottles is also increasing year by year, so the quality of beer bottles has become a prominent problem. Among the many indicators that affect the quality of beer bottles, impact resistance is an important safety indicator for beer bottle products. The weakness of glass bottles is brittleness, beer bottles in the production of packaging, beer filling, transportation and use of circulation process, the collision between the bottles or bottles and other hard collision is often occurred. This kind of collision will make the mechanical strength of beer bottles significantly decreased. Due to the current consumption habits and the reuse management of beer bottles, the strength of beer bottles has plummeted. Some beer bottles with poor quality and high reuse times have reduced their impact resistance index, which makes it difficult to resist normal collisions, thus burying hidden dangers for bottle explosion. Therefore, the production of beer bottles should meet the requirements of impact strength in the national standard GB4544-2020. The current standard stipulates: for disposable bottles with V≤ 530ml and recyclable old bottles ≥ 0.2J, recyclable new bottles ≥ 0.4J;V>530ml disposable bottles and recyclable old bottles ≥ 0.3J, recyclable new bottles ≥ 0.6J. The actual test method is shown in the national standard GB/T 6552-2015 glass container mechanical impact test method.

1. influence the impact strength of beer bottles

The mechanical strength of beer bottles is not only related to the shape of the bottle, the thickness of the bottle wall and the thickness distribution, but also closely related to the uniformity of the glass, the micro and macro defects and the surface state. The theoretical strength of glass refers to the strength of its structural bonds, and the strength of its structural bonds varies depending on the composition of the glass. It is well known that ≡ Si-O-S ≡ bonds have a very high strength, whereas ≡ Si-O-R (alkali metals) have a very low strength. In theory, to obtain high-strength glass must be added to a large number of high-charge, small-volume cationic glass network formers, but this will bring great difficulties or increase the cost of glass melting and molding, which is practically impossible. The theoretical strength of the beer bottle can be calculated by the structural bond, its strength is very high, much stronger than steel, in fact, its theoretical strength is thousands of times the actual strength. The reason why the actual strength is so low is caused by lattice defects, stripes, cracks, etc., and another reason is its inhomogeneity. Due to these factors, the actual impact resistance of beer bottles is relatively low.

Influence of shape and wall thickness of 2. bottle on impact resistance

The shape of the bottle has a great influence on the mechanical strength. The more complex the shape, the lower the strength. This is due to the stress concentration of the complex shape of the bottle. At present, most glass factories in our country adopt the bottle shoulder to be relatively gentle, with two bending points acting as buffers, and the stress distribution is uniform. There is a protruding ring above the bottle heel, which has better impact resistance. However, from the previous sampling results, the impact strength is not satisfactory, which is mainly due to the actual process level, production conditions and technical level of China's glass industry, and the influence of various micro and macro surface defects on mechanical strength analyzed above, which makes the actual impact resistance value of beer bottles low.

3. Factors to be Considered in Improving Impact Strength

In the normal production process, if the product appearance, physical and chemical performance indicators of the glass bottle are relatively good, and the qualified rate of the finished product is relatively high, the fly in the ointment is that the impact resistance index is unstable, which is mostly caused by insufficient glass homogenization. Several factors need to be considered:

1. Fine-tune the glass composition, reduce the high temperature viscosity of the glass, and make the glass liquid easy to clarify and homogenize. (The data provided is for reference only)

(1) On the basis of not significantly increasing the cost, some quartz sand is put into use instead of some ordinary silica sand, and the content of glass composition is reduced to 1.8-2.0% as far as possible.

(2) Intentionally increase the content of CaO in the glass composition, so that the combined amount of CaO + MgO is close to 12.3-12.5%, which can be directly increased and other components naturally decreased. In the process of adjustment, any adverse reactions will stop immediately.

2. Check the granularity of ore raw materials. Requirements for granularity (wt%): quartz sand 20 mesh ≤ 0.1, -150 mesh ≤ 7; Limestone (dolomite) 10 mesh ≤ 0.5, -150 mesh ≤ 7; Fluorite 40 mesh = 0, -200 mesh ≤ 5, this is to find out the reason from the raw material itself to prevent too coarse or too fine, the purpose is to ensure that the batch materials can be mixed evenly to speed up the melting and clarification of glass homogenization; At the same time, the storage limit of ore raw materials should be guaranteed, batch testing should be done, clearly marked, and used in line with the principle of "first in, first out.

3, strengthen the quality management of broken glass, try to reduce the content of foreign glass, control its furnace.

4, strengthen the control of quartz sand moisture, due to the quartz sand water content is large and unstable, so according to the provisions of the timely detection of its water content, after detection according to the amount of quartz sand dry base, the amount of quartz sand wet base carefully and timely adjustment shall not be wrong.

5. The control of the raw material weighing system, weighing is an important part of the batching process, the accuracy of the weighing of various raw materials directly affects the composition of the glass and the quality of the product. The batching scale is checked once a week with the standard weight at full load, and the required error is ≤ 0.1%. If the standard weight is not enough, the "physical calibration method" can be used to check and correct in time.

6. Control of raw material preparation system

(1) Blanking sequence of raw materials: After weighing, the sequence of raw materials discharged into the mixer should be: quartz sand → soda ash → limestone. At the same time, the three raw materials are required to enter the mixer as synchronously as possible (Yuanxiao principle), which is the key to improve the uniformity of the mixture.

(2) Uniformity and moisture content of the batch material: the mixing time of the mixer is divided into dry mixing time and wet mixing time, which determine the uniformity of the batch material; The water addition time determines the moisture content of the batch material. Strive for the uniformity of the mixture to reach more than 98%, and control the moisture of the mixture to 4-5% (mixer discharge port).

7, the bottom temperature is an important indicator, normal production should strictly control its changes, bottom temperature stability is the basis for stable production, but also we adjust all process parameters.

8, glass liquid level control: automatic control of feeding, the glass liquid level is required to be stable in the standard height ± 1.0mm range; manual operation, allowing the glass liquid level to stabilize in the standard height ± 1.5mm range fluctuations. When special circumstances cause the glass liquid level to fall to catch up with the liquid level, it is required to be executed at a speed of 0.5mm/hour (if it is reduced more, it depends on the situation). At the same time, the material pile shall not exceed 2/3 of the furnace length and be evenly distributed, and the bubble boundary shall be stable near the top of the kiln.

9. Control of kiln discharge capacity: during normal production, the change of kiln discharge volume is stable within <2%. when changing products, the increase and decrease of discharge volume shall be kept stable by adjusting the number of machines. If the weight of the product is very different, you need to do some preparatory work and response plans in advance. Bottle production should be communicated in advance whether it is to stop or change production. It is absolutely not allowed to stop and open if you want! There must also be a plan to increase or decrease the speed of the machine. You can't increase or decrease it if you want, and you can't do it at will. It is very important to maintain the basic stability of the kiln discharge.

10. Kiln pressure control: When the system is under normal automatic control, it is required to control the kiln pressure change near the pressure measuring point within the range of ± 3Pa (except for reversing). When manual operation is adopted, the kiln pressure change near the pressure measuring point is allowed to fluctuate within the range of ± 5Pa. To prevent the kiln pressure fluctuation is too large.

4. epilogue