Analysis and treatment of die plugging of aluminum extrusion die and case practice analysis

One stop die and extrusion die design

1.Is there any relationship between die plugging and unreasonable extrusion die design?

We know that aluminum extrusion is the flow of aluminum alloy in the mold to form a certain shape.The core idea of mold design is to ensure that the flow velocity of aluminum alloy at all positions is basically the same when flowing through the mold.The extrusion process of some profile(asymmetric),large cantilever and flat wide profile is easy to cause mold plugging.

What is the relationship between blocking die and extrusion die design?

The reasons for mold plugging caused by unreasonable mold design generally lie in the unreasonable design of flow hole,welding chamber and working belt length in mold design;The mold strength design of flat and wide profile is not in place,and serious mold deformation can also lead to mold plugging;

In addition to the above common factors,there is another factor that can also lead to mold plugging,that is,the design of the empty tool of the mold.Everyone knows the function of empty knife.Empty knife is an important factor to ensure the smooth passing of aluminum products and the quality of aluminum products.If the empty knife of the die is too small,it is easy to scratch the aluminum surface,and even cause mold plugging.If the empty knife of the outlet is too large,it will weaken the strength of the working belt,cause deformation and collapse of the working belt,and reduce the service life of the extrusion die.

After the aluminum head protrudes out of the working zone,due to flow velocity,wall thickness,resistance and other reasons,it does not necessarily flow radially,and most of it will swing,bend and shake.If the design of the empty tool of the die is too small or unsmooth,the aluminum material head will be blocked or bonded after friction,so that the material head cannot move forward,but the extrusion still fills the empty tool space of the die with aluminum,resulting in die plugging.

The relationship between die plugging and extrusion production

2.Classification of die plugging caused by extrusion

Characteristics of aluminum extrusion blanking die:

Die plugging refers to a phenomenon that the aluminum matrix is stuck at the working belt or the empty knife.During the die plugging process and after that,the extrusion force rises to a high level,and sometimes it is extruded out in the shape of the empty knife.It cannot correctly reflect the real situation of the profile after blocking the mold,which must be corrected.

Cause classification of mold plugging:

There are many reasons for mold plugging,and uneven mold flow rate and extrusion operation are the two main phenomena.The probability of other conditions is very small,and some or one sentence can make it clear.I hope you don't say I'm stingy when there are too few details.

1:Mold blocking caused by mold reasons

2:Die plugging caused by extrusion operation

3:Blocking caused by tooling

4:Blocking caused by equipment reasons

5:Mold plugging caused by foreign matter pressing in

6:Blocking caused by temperature

7:Blocking caused by speed

8:Mold plugging related to profile processing shape

9:Blocking caused by other defects(bubble,tear,material,center position,intense shrinkage,intense strength change,overburning,etc.)

3.Other factors affecting mold plugging

For example,some mold matching masters adjusted the upper mold guide 180 degrees to install the mold,and the long side of the aluminum profile was blocked;The reverse installation of the mold leads to empty knife and advanced aluminum,resulting in mold blockage;In the process of mold processing,the fracture or pressure deviation of the core head and small feet leads to the drastic change of the aluminum alloy flow rate and mold plugging.

4.Real case of mold plugging

Mold plugging often occurs because of the complex shape of aluminum profiles.For some individual aluminum profile molds,if the extruded aluminum profiles are qualified,it is extremely difficult to discharge at the export stage,and the mold is often blocked because of the rapid flow rate of part of the outlet(plane part or thin wall part).If the discharge is trimmed evenly,there will be waves on one side of the extruded profile,and the profile is unqualified.

There is a set of extrusion die,using 1800 ton machineφ184 extrusion cylinder,with a 40*40mm cavity on one side of the aluminum profile and a wall thickness of 2.5mm,is connected with a 0.8mm wall thickness arc arm extending to the other side.The overall outer diameter of the profile is 210mm,the cantilever diameter is 170mm,and the arc length is larger.The meter weighs about 1.5.No matter how large or small the machine can be consumed,it must be used inφ184.It belongs to the expansion mode.

Due to the great difference in the thickness of the walls on both sides,the working zone must be retracted locally in the thin-walled arc,and the local thin-walled extension at the far end must be first out.Slowly wrinkle in the working belt,quickly bend to the thick place,wrap the material head for 10 times,and block the mold for about 7 times.

After that,take the thin-wall out to unload and level it before putting it on the machine(note that the rod should be short,the temperature should be high,and the mold replacement and unloading time should be compact),for 2-3 consecutive times,and the number of mold plugging should be reduced to 12/10.

There is also an extrusion die.The outer diameter of the aluminum profile is 80*80mm,the outer wall is 4mm,and the inner diameter is 2.5mm.There are 12 male heads of various shapes and sizes inside,and the middle male head is particularly small.After being put on the machine,some male heads are biased and broken,and then the die is blocked.If the machine is not stopped in time after blocking,more male heads are broken.This set of molds is a one-time mold for customers,with a quantity of more than 2 tons of aluminum profiles.Customers provide 3 sets of molds.After 2 months of aluminum consumption,N sets of extrusion dies were discarded,and several qualified materials were not consumed.All extrusion dies were damaged due to die plugging.

1、Treatment method:

1.The working belt at the middle part is shortened as a whole to reduce resistance;

2.Lubricate all empty knives and drainage grooves to reduce adhesion and friction;

3.The male head plinth is lowered to reduce collision and shaking;

4.Press up slowly at high temperature,unload the mold when the aluminum is about to be taken up,apply graphite smooth oil to the empty knife of the middle part of the mold,and then press up slowly.The extruded profile is padded with a base plate to guide the straightness without shaking.Two sets of moulds are used to consume more than 2 tons of profiles,but the thickness of the middle rib is a little biased,so the customer can bear it and complete the task.

The more complex the shape of aluminum profile,the higher the difficulty of aluminum consumption,and the more attention should be paid to the uneven flow rate.This kind of extrusion die should adopt the method of high temperature and slow extrusion,taking the completion as the higher criterion,rather than rushing for speed and output.

Key words:gusset mold,profile mold