Mold core, mold sleeve is extruded molding mold, mold core fixed on the mold core base, its role is to fix and support the core or cable core, so that the plastic into a ring, and in a certain direction into the mold sleeve, by adjusting the mold core seat bolt to adjust the relative position of the mold core set. The mold cover is fixed on the machine head by means of the mold cover, and the function of the mold cover is to make the plastic enter the hole through the gap formed by the inner cone hole and the outer cone of the mold core.

Three forms of plastic extrusion mold:
1. Extrusion mold

The core of the extrusion mold has no tubular bore part, and the core is shrunk behind the bore of the mold sleeve. The molten plastic (hereinafter referred to as the material flow) is finally shaped by pressure through the mold sleeve, and the extruded plastic layer has a tight structure and a smooth appearance.

1.1 Advantages of extrusion mold:

a. The extruded plastic layer has tight structure and smooth appearance.

b. Suitable for extrusion plastic elongation ratio is too small.

1.2 Disadvantages of extrusion mold:

a. The amount of glue is much lower than the extruded tube type

b. Easy to cause serious eccentricity of the plastic layer,

c. Product quality depends on the mold

d. extrusion has higher requirements for the accuracy of the mold

e. The bending performance of the extruded core is not good

2. Extrusion mold

The extrusion mode in which the die core has a tubular bearing part and the end face of the die core extends out the end face of the die sleeve or is flat with the end face of the die sleeve is called the extrusion tube type. Because of the existence of the tubular bore part of the mold core, the plastic is not directly pressed on the cable core, but moves forward along the tubular bore part, forming a tube first, and then being stretched and coated on the wire core or cable core.

2.1 Advantages of extruded tube mold:

a. Fast extrusion speed;

b. Simple production operation, easy core adjustment;

C. Easy to assemble mold;

d. After stretching, the molecules of the plastic produce directional arrangement to improve the mechanical properties of the sheath;

e. sheath thickness is easy to control;

2.2 Disadvantages of extrusion mold:

a. Poor density of plastic layer;

b. The binding force between the plastic layer and the core is poor;

c. Extrusion appearance is not as round as extrusion;

3. Semi-extrusion mold

The mold core has a tubular bearing part, but it is relatively short. The extrusion method of the end face of the die core bore is called semi-extrusion, which is the transition form of the extrusion tube type and the extrusion type.

Second, hot extrusion molding principle

1. Small melting viscosity: tube extrusion, extrusion can be

2. Large melting viscosity: tube extrusion

3. Poor fluidity after melting: extrusion or semi-extrusion

4. Need to extrude dense: extrusion

Third, the choice of extrusion mold size

1. Extrusion type:

Internal mold: The maximum diameter that can pass through the core wire, generally small diameter =d+0.05~0.5mm, large diameter =d+ 0.5~2mm

External mold: consistent with the extrusion diameter, generally small diameter =D+0~0.5mm, large diameter =D+0.5~1.5mm

2. Extruded tube type:

Internal mold: The maximum diameter that can pass through the core wire, generally small diameter =d+0.05~1mm, large diameter =d+ 0.5~8mm

Outer mold: = Outer diameter of inner mold tube + (2.5~4) t

Four, extrusion mold design requirements

1. Where the mold surface in contact with plastic should be smooth, the finish should be high, and it is more ideal if polished by chrome plating.

2. The mold should be interchangeable, and the dimensional tolerance requirements of various parts should be considered.

3. The plastic has a certain pressure in the mold, and the mold sleeve Angle must be greater than the mold core Angle.

4. Proper selection of mold materials can improve the service life. The mold should have certain hardness, strength, no rust and corrosion resistance.

5. When designing the extruded tube mold core and mold sleeve, the relationship between the gap area formed by the mold core and the cross-sectional area of the product pipe should be considered, which is called the tensile ratio.

Qingdao Tianxing Cable Co., Ltd. is a technology enterprise specializing in the production of wire and cable in Shandong Province, with more than 150 sets of domestic excellent cable production equipment and testing equipment, excellent production technology, modern testing equipment, to ensure stable product quality and timely supply. The company's main products are power cable, mineral cable, high life wire and cable, radiation crosslinked cable, control cable, computer cable, photovoltaic cable, communication cable, data cable, low smoke halogen free cable, flame retardant series wire and cable.