Thiết kế chế tạo hệ thống làm nguội trong khuôn ép nhựa

Bài giảng Power Point khá chi tiết và hệ thống làm nguội trong khuôn ép nhựa giúp cho các bạn sinh viên chuyên ngành Cơ khí chế tạo máy, Công nghệ tự động (trường Đại học Sư phạm Kỹ thuật thành phố Hồ Chí Minh)

Some attention when designing

Cooling mold

Cooling core

Some attention when designing

or 10mm) for easy processing and avoid the flow rate of the cooling fluid is different

5

Pay attention

to the cooling of the thickness part of the product

4

Pay attention

to the thermal conductivi

ty of cast materials

3

Split system cooling off areas

to avoid too long cooling channels leading to the large temperature difference

6

Note to warping phenomenon due

to the different shrinkage when the thickness of different

products

Helix baffle Spiral baffle

BAFFLE

A bubbler is similar to a baffle except that the blade is replaced with a small tube The coolant flows into the bottom of the tube and “bubbles” out of the top, as does a fountain The coolant then flows down around the outside of the tube to continue its flow through the cooling channels.

The most effective cooling of slender cores is achieved with bubblers The diameter of both must be adjusted in such a way that the flow resistance in both cross sections is equal The condition for this is:-

Inner Diameter / Outer Diameter = 0.707

BUBBLER

THERMO PIN

Công thức tính độ khuếch tán của nhựa nóng chảy

Nói cách khác tăng gấp đôi chiều dày khuôn sẽ làm tăng thời gian làm nguội lên 4 lần

Reynolds number

Coolant flow types and corresponding Reynolds number ranges

• Reynolds number and coolant flow

The Reynolds number is defined as:

•

where ρ is the density of the coolant, U is the

averaged velocity of the coolant, d is the diameter

of the cooling channel, and η is the dynamic

viscosity of the coolant.

•