FIELD OF INVENTION
The present invention relates to an improved arrangement for reaming operation in horizontal plane for achievement of higher accuracy. More particularly, the present invention provides an arrangement of jig & guide bush for reaming operation where inaccessibility and accuracy is a major problem.
BACKGROUND ART
Landing Crafts is a class of vessels used in Indian Navy extensively for transporting primarily Man, Materials and Vehicles from Sea Ports to locations nearby sea beaches. Bow ramp of these vessels as shown in Fig. 1, plays a crucial role in embarking and disembarking Man, Materials and Vehicles.
Necessity arises to have hinges of these Bow ramps bored to near perfection for smooth operation of its Ramp and Flap assembly as shown in Fig.l. Bow Ramp (LCU project) flap hinge and main hinge bore machining is a major challenge for us with maintaining a high level of accuracy and above mentioned criteria. Initially the reaming of Bow Ramp hinges was done by conventional reamer spindle arrangement as shown in Fig.2. This leads to consumption of more man days with less accuracy of reamed holes. Due to inaccurate conventional reaming operation, securing of flaps becomes very difficult, time consuming with very low probability of smooth operation.
In view of above we developed an arrangement of jig & guide bush for reaming operation where inaccessibility and accuracy is the major problem. Basically we intend to a process improvement for reaming operation in horizontal plane by which we can get high accuracy with less effort.

(a) Draw backs in existing state-of-art & how the draw backs have been overcome by the proposed inventions:
Followings were the drawbacks for existing system:
1. Conventional reaming process is consuming large human effort and man-hours.
2. Chances of improper reamer guide bush & extension bush arrangement.
3. Reamer was getting blunt very frequently and chances to break.
4. Reamer centering in respect to the hole was not up to the mark.
5. Extension guide bush of reamer does not hold the center of reamed hole.
6. Frequent thinning of guide bush of reamer, resulting bad finishing & lower accuracy level (ovality was observed on reamed holes).
The inventor proposes improved arrangement of reaming operation in horizontal plane for achievement of higher accuracy by developing a jig & guide bush arrangement for reaming operation where inaccessibility and accuracy is the major problem.
SUMMARY OF INVENTION
Therefore such as herein described there is provided an improved arrangement for reaming operation in horizontal plane for Bow ramp of vessels comprising of a jig fixture and ajig holding bar ; a taper bush and a guide bush; and a threaded spindle and a feeding nut wherein a frame of a reamer jig, comprising an elongated base with a post erected on one end and another post erected on the other end, while between the two posts there is located an upstanding spindle and bush connection.
The principle object of the present invention is to reduce the reaming time and reduce

the required human effort and man-hours. Therefore, during reaming operation no expertise required and it can be done by single person.
Another object of the present invention is to avoid damage of reamers set used for the activity and to maintain reamed holes within tolerance limit.
Yet another object of the present invention is to facilitate highly accurate rimmed holes for easy fitment of Bow Ramp Flaps. Shorter time is taken from the conventional reaming operation.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 (a) and (b) illustrates the bow ramp flap hinge and bow ramp flap respectively in
accordance with the present invention;
Fig.2(a) and (b) illustrates spindle reamer arrangement and reaming in progress as a prior
art;
Fig.3 illustrates the components of the spindle reamer arrangement as a prior art;
Fig.4(a) and (b) illustrates the engineering drawings for jig and the jig holding bar in
accordance with the present invention;
Fig.5 illustrates the photograph of trial implementation in accordance with the present
invention.
DETAILED DESCRIPTION
The present invention provide a jig or work holder for use in any line reaming which will have a substantially floating action on its supporting bed to dampen the transfer of

vibrations to the work holder. During the reaming of Bow Ramp hinges the securing of flaps becomes very difficult and the time taken for chances of smooth operation becoming less. In view of above the inventors have developed an arrangement of jig & guide bush for reaming operation where inaccessibility and accuracy is the major problem Therefore the present invention is intended to adapt the jig and reamer arrangement so that they cooperate in a novel way to produce a perfectly round hole even though the hole being reamed is oval-shaped or has/become otherwise distorted. More specifically in this connection, the invention employs a reaming operation in conjunction with a jig.
The disclosed jig for use with the line reaming may have clamping jaws which are adapted to cooperate with the reamer to centralize the work piece within the jig/work holder while it is being clamped therein so that the reamed holes will be in true alignment.
Fig.4 (a) and (b) shows a frame of a reamer jig, comprising an elongated base with a post erected on one end and another post erected on the other end, while between the two posts there is located an upstanding spindle and bush connection which, together with the said posts, forms a reaming arrangement.
Since the post and bush are, in some of the operations of the reamer, subjected to considerable strain tending to separate; them there is provided a jig holding bar made fast at both ends fastened with nut and washer whereby the post and jig holding bar are held rigidly together. For convenience in manufacture, the holding bar is made separate from the post and guide bush as shown in Fig.5.
A taper bush is provided at other end in middle hole of jig with an inner face tapering from that side of the bush toward the post to the side of the bush toward the post and the bush has an entering screw-threaded spindle portion concentric with the axis of the bush

and extending into the taper portion. Adapted to the screw-threaded spindle portion is an exteriorly shrink fit guide bush provided on one face of jig fitted with a circular series of thread by means of which the bush may be screwed, by hand if desired, into the threaded part. The threaded portion of the guide bush is long enough to engage a beveled split, wedge like feed nut conforming to the taper structure on the inner surface of a taper bush.
Reamer segments can be secured against horizontal/longitudinal movement with respect to spindle by any suitable means. Jig holding bar can be secured in a number of ways to spindle so that it will be constrained to rotate therewith. At the present time all work is held in the hand while reaming.
1. This jig & guide bush arrangement basically used for horizontal plane but it can be used in vertical plane also irrespective of the size of the hole.
2. Depending upon the size of the required hole the dimensions of this jig and guide bush arrangement may changes slightly.
3. This fixture is very economical and can reuse for same size of holes.
TANGIBLE GAIN (COST BENEFIT) I. MATERIAL SAVING :
No. of reamer required per ship = 5 reamers (1 set of consists of reamer from 60.00 mm,
60.5 mm, 61.00 mm, 61.5mm and 62.00 mm)
General experience/trend of reamer getting broken/blunt = After reaming 10-12 holes.
From YD 2095 to YD 2099 ship during reaming process of 15 nos. holes' reamer getting
blunt/broken = NIL
No. of reamers saved from getting blunt = 1 set (05 nos. reamers)
Price of each reamer = Rs.35,000
Cost of saving 05 nos. reamer (01 set) = 35,000 x 5 = Rs. 1, 75,000

II. MAN-HRS SAVING :
Previous trend for manpower requirement in this reaming activity = 4 Fitter X 40 hr = 160
Man-hours ss
After implementation of Jig & bush arrangement in Reaming process = 2Fitter X 24 hr = 48
Man-Hours
Man Hours saved per ship = 112 Man-hrs.
DETAILED MATERIAL REQUIRED FOR THE PROCESS :
1. Preparation of design of jig with proper dimensions for improvement of the reaming process.
2. Collection of material from MFOS Store.

2.1 M.S. Round Bar dia. 40 x200 mm length.
2.2 Gun metal Round Bar dia. 40 x70 mm length.
2.3 M.S. plate 150x200x25 mm.
2.4 02 nos. bolts M16 x 80 Long with nut & washers.
2.5 02 nos. feed nuts.

3. Preparation of gun metal bush from round bar and M.S. plate machining as per design.
4. Drilling of 02 nos. round bar was done by drill bit 14.5 mm, depth of hole was made 35 mm and tap of M16 was done up to depth of 30 mm.
5. M.S. plate was drilled at center, then M.S. plate was drilled M18 for slot purpose.
6. Gun metal bush was shrink fitted with M.S. plate.
7. Round bar was welded over bow ramp hinge plate.
8. Jig is now ready for reaming.

ADVANTAGE OVER OTHER KNOWN ALTERNATIVES INCLUDING IMPORTED ALTERNATIVES :
In present scenario boring was an alternative arrangement in place of reaming operation. But in our case dedicated boring arrangement (fit-to-size) required for the whole operation, which is required separate design and separate procurement resulting higher costs respect to reaming arrangement. As because the whole size is less and over the length of the Bow ramp is long so sagging of the boring bar may arise and effecting inaccurate boring.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

We claim :
1. An improved arrangement for reaming operation in horizontal plane for Bow
ramp of vessels comprising of:
a jig fixture and a jig holding bar;
a taper bush and a guide bush ; and
a threaded spindle and a feeding nut wherein a frame of a reamer jig, comprising an elongated base with a post erected on one end and another post erected on the other end, while between the two posts there is located an upstanding spindle and bush connection.
2. The arrangement for reaming as claimed in Claim 1, wherein the said taper bush is provided at other end of jig with an inner face tapering from that side of the bush toward the post to the side of the bush toward the post and the bush has an entering screw-threaded spindle portion concentric with the axis of the bush and extending into the taper portion.
3. The arrangement for reaming as claimed in Claim 1, wherein said screw-threaded spindle portion includes an exteriorly threaded guide bush provided on one face.
4. The arrangement for reaming as claimed in Claim 3, wherein said threaded portion of the guide bush is long enough to engage a beveled split, wedge like feed nut conforming to the taper structure on the inner surface of a taper bush.
5. The arrangement for reaming as claimed in Claim 1, wherein said bush is made of Gun metal and is shrink fitted with M.S. plate.

6. The arrangement for reaming as claimed in Claim 1, wherein said reamer segments are secured against horizontal/longitudinal movement with respect to spindle by any suitable means.
7. The arrangement for reaming as claimed in Claim 1, wherein said Jig holding bar is secured in a number of ways to spindle so that it will be constrained to rotate therewith.