DESCRIPTION

TECHNICAL FIELD

Design and fabrication of a special mandrel for installation of bush on Wing spar #6 assembly of LCA Aircraft

BACKGROUND OF INVENTION

This is one of the critical sub-assembly in LCA Aircraft where pylon assembly will get assembled at final assembly stage and it is one of the major load carrying member of this aircraft. It is an Interchangeability (ICY) locating point where the closely controlled tolerance to be maintained within 50 microns for the distance of 807mm to avoid the misalignment at next assembly stage.

To achieve the above dimension, the bush pressing process is highly significant stage because the bush to be pressed in blind hole having complex profile at the depth of 150mm without rework or rejection of detail components which are fabricated through long cycle machining.

Any shift or miss alignment in bush pressing, it is very difficult to rework by removal of bush. While removing the bush it may damage the component as the bushes will be removed by machining process due to blind hole.

SUMMARY OF INVENTION

In order to make the assembly easy and to reduce the risk factor while pressing the bush, a mandrel has been designed, fabricated and used in both assemblies of LH and RH wing of LCA spar # 6 sub-assemblies.

Using this mandrel, bush pressing process carried out by achieving interchangeability tolerance, line-ability as per wing assembly requirement.

DRAWINGS

Fig.l Sub-assembly drawing where bush to be pressed Fig.2 Designed Mandrel Sketch for bush pressing Fig.3 Designed Ram Sketch for bush pressing Fig.4 Designed Bush Sketch for bush pressing

PROCESS DETAIL DESCRIPTION:

Spar # 6 assembly involved spar #6 and 4 bushes of each. Spar # 6 made with Al-Alloy forged block of size 220X325X1100(GD) mm and bushes are made with CR Steel.

The raw material details as follows:

This is one of the critical sub-assembly in LCA Aircraft where pylon assembly will get assembled at final assembly stage and it is one of the major load carrying member. It is an Interchangeability (ICY) locating point where the closely controlled tolerance to be maintained within 50 microns for the distance of 807mm to avoid the misalignment at next assembly stage.

To achieve above dimension, the bush pressing process is very significant stage because the bush to be pressed in blind hole having complex profile at the depth of 150mm without rework or rejection of detail components which are involved long cycle components.

Any shift or miss alignment in bush pressing, it is very difficult to rework by removal of bush. While removing the bush it may damage the component as the bushes will be removed by . machining process due to blind hole.

In order to make the assembly easy and to reduce the risk factor while pressing the bush, a simple mandrel has been designed, fabricated and used in both assemblies of LH and RH wing -of LCA spar # 6 sub-assemblies.

Using this mandrel, bush pressing process carried out by achieving interchangeability tolerance, line-ability as per wing assembly requirement.

ADVANTAGE:

1. Easy to press the bush by using the mandrel

2. Line-ability will be maintained

. 3. Rework can be avoided

4. Simple and easy to fabricate the mandrel

5. Bushes and part can be saved from rejection.

6. Assembly time will be reduced