Typical hollow type aluminium extrusion die design classifications
In this article,we introduce eight types of typical hollow type aluminium extrusion die design:1.Equal hollow hole design,2.Unequal hollow hole design,3.Predeformation design,4.Integrated whole hollow die design,5.Guide feed hollow die design,6.New structure for multi-cavity hollow type die,7.With floating insert hollow die,8.Semi-spheroidal type hollow die design.
1.Equal hollow hole design
The thickness difference between each part of section should be less than 3 times.Ignoring subdivision hollow hole ratio,only considering total hollow ratio,the distance of each hollow hole to mandrel is approximately equal and the section area &shape is same or approximately same,when the die strength is enough the hollow ratio should be increased as far as possible ,so that this design can reduce extrusion force and reduce die deformation.Under this design the metal follow is controled by reasonable bearing,cavity,hollow hole arrangement,welding chamber,mandrel shape and size etc.This design can simplify processing,decrease design and die correction difficulty and improve die trial and correction success probability.
2.Unequal hollow hole design
In order to reasonably distribute metal flow and speed,according to section shape,thickness and size to design different shapes,size and unequal distance to hollow hole,under reasonable total hollow ratio the subdivision hollow hole ratio should be considering and it should match section shape and section size.For this unequal hollow hole design,the hollow hole is the main factor for adjusting metal follow in consideration.Regarding die correction for this kind die,the hollow hole and its size should be adjusted,but effects of die bearing repairing can not work evidently.
In order to reasonably control metal follow,and correct bad section deformation,we can try to proactively design opposite direction of deformation for the port shape to get good section as per the drawing requirements.
4.Integrated whole hollow die design
Design die mandrel and die cap as a integrated whole,it consits of hollow port ring,integrated whole hollow die and backer.This design can improve loading bearing force of long section length.However,this design is not easy for die manufacturing,so it is normally used for longer sized semi section.
5.Guide feed hollow die design
This design consists of special die mandrel,die cap and weld chamber.It uses bridge to protect section arm from fast metal flow,change weld chamber height and adjust metal follow speed.The design is suitable for complex section shape and large different thickness and bigger slenderness ratio sections.
6.New structure for multi-cavity hollow type die
Under the limit of existing extrusion press and extrusion container size,when only one press and only one container diameter can be available,for making thin thick tube and complex micro section with high precision,multi-cavity hollow type design die is an unrefusable choice,for solving difference of thickness,many design find more solution from die design,manufacturing and assembly etc.The right image shows the new structure for multi-cavity hollow type die.It can make the two mandrels close,to reduce connection brigde gap,the middle part can get better stiffness.When die bears force,the middle parts cannot easily bend.Because the hollow bridages are in the same position,deformation is even,the midldle part cannot incline.So the die deformation cannot influence the secion thickness precision,the metal flow is even and section shape turns better.For this die design,the hollow port can be large to reduce resistance.
7.With floating insert hollow die
Floating insert ring consists of connection pin,ring and screw.This design can help adjust thickness difference by the gap of insert ring and connection pin.In the weld chamber when the metal flow passes through the ring shape hollow hole,only under the condition of same gaps for each ring shape hollow hole,the metal flow in the removable insert ring can be even and the force is uniform in the weld chamber.When the force on floating insert ring is not even,the floating insert ring will help ajust the gaps and makes the gaps uniform and the force on metal flow in the weld chamber will change into balanced status.
8.Semi-spheroidal type hollow die design
For improving flat hollow die life,flat hollow bridge can be designed into semi-spheroidal shape.The tensile force in the connection part of the bridge is only 1/4 of slenderness die.This design can reduce crack effectively.The weight of semi-spheroidal die is only 1/10 of of slenderness die,but the hollow hole covering area increases,under same extrusion speed,the force is only 96% of slenderness die.
Employing different reasonable die designs can get good section shape and size precision，improve mechanical property and reduce extrusion force as possible,increase the extrusion speed to save energy.Refering many practice,the designs are effective:production capacity is raised and quality enters a new high level.
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