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Plastic bottle is so blown out
Dec 26, 2016

Classification of blow molding

1, according to the different molding methods

Extrusion-blow-molding: simple production methods, high output, low accuracy, more.

Injection-blow-mold: high precision, good quality, high price, suitable for high volume products.

2, according to the different forming process

Ordinary blow molding;

Stretch blow molding: tensile, high strength, good gas tightness.

Extrusion-drawing-blow molding (referred to as crowd-drawing-blow)

Injection-stretch-blow-moulding (the note-la-blow)

3, tube layers according to different classification

Single layer blown;

Multi-layer blow molding: comprehensive performance, and production complex, applicable to packaging products that require packaging.

Blow molding device

1, needle flushing technique

Operation: closed-the parison wall worn out – blowing – blow the needle retraction-healing-melt

Features: continuous Rotary blow molding, small containers, with handles.

2, the top-blown method

Procedure:-closed-bottom clamp-the top opening ventilation--core-inflation-rotating tool removal of residual material

Features: core inflatable mandrel, simplified

Factors affecting the blow-moulding process

01, air pressure

Blow molded, compressed air has two purposes, one is to make the tube swells and close the cavity wall, formed shape; the other is cooling. According to the plastic variety and the temperature difference, the air pressure is not the same, general control between 0.2-0.7 MPA, product is most appropriate in forming shapes, patterns show clear pressure.

02, inflatable speed

In order to shorten the time of blowing in order to facilitate the products get more uniform thickness and better surface, air speed (through the volume of air per unit of time) are as large as possible, but it should not be too large, otherwise it will bring adverse effects to the products.

03, blow-up ratio

Products are usually the size of type and dimension of the Lake called blow-up ratio. When the parison dimensions and weight is constant, the products of larger size, die inflation greater than. According to the cultivar, properties, plastic products, shapes and sizes and parison dimensions to determine inflation than size. Usually 2, blow-up ratio control in 4 times.

04, mold temperature

In order to ensure product quality, mold temperature should be evenly distributed, mold temperature remained at 20-50. Mold temperature too low, will reduce the NIPS plastic extensibility, easy to blow and make products in this part of the thickened, while difficult, products such as contour and pattern is not clear. Mold temperature too high, extend the cooling time, the production cycle is lengthened. Products mold deformation and contractions increase. Mold temperature depends on the plastic variety, when plastic glass at high temperature, high temperature can be used, otherwise the temperature as low as possible.

05, the cycle time

Blow molding cycle consists of extruded parison, interception of parison. mould, blowing, cooling, gas, open cross, check out products (subsequent trimming, matching, packing excluded).