tooling modification of cnc_hbm

Manufacturing of Pull-Stud for PAMA CNC Horizontal Boring

Machine

Case Study ByMr. Pradeep Kumar Verma

Asst. Engineer, Grade-II&

Mr. B ThimmaiahArtisan, Grade-II

HEAVY MACHINE SHOPELECTRICAL MACHINES DIVISION

BHEL-HYDERABAD

BHEL- Hyderabad

EM Division of BHEL Hyderabad manufactures

Turbogenerators from 5MW to 150MW air cooled and 270MW hydrogen cooled machines.

Heavy Machine Shop of EM Division does Rotor machining operation ( Turning, Slotting, Drilling, Boring & Tapping operation), machining of turbine casings(steam and gas from 30MW to 250MW) and generator stator frames.

Critical machines in Heavy Machine Shop consists of Rotor Slot Milling machine (HELLER-Germany), CNC Horizontal boring Machine (PAMA-Italy), CNC Center Lathe (TACCHI-Italy).

HEAVY MACHINE SHOP EM DIVISION-BHEL HYDERABAD

AN INTRODUCTION

MACHINE DESCRIPTION

CNC Horizontal Boring Machine (PAMA-Italy)

SPEEDRAM 6 SPINDLE HEADSTOCK

Boring spindle diameter mm 225Boring spindle axial travel (W) mm 1600Ram section mm 600 x 725Ram axial travel (Z) mm 1600Total axial travel (W+Z) mm 3200

SPINDLE SPEEDSpeed range rpm 5 - 1150

POWERSMain motor kW 130

TRAVELSMax. headstock vertical traverse (Y) mm 5000Column longitudinal travel (X) mm 15000

TABLETable Longitudinal Travel (V) mm 2500Table Size mm 4500 x 5000Table Rotation (B) 3600

Table Capacity Kgs 70,000

BHEL- Hyderabad

MACHINE APPLICATION

Machining of Steam Turbine & Gas Turbine Casings: Parting Plane & Connecting Flange-Milling, Drilling, Boring, Reaming Tapping & Butter Threading.

Machining of Turbo-generator Stator Frames & End Shield: Bearing Seating, End Shield Seating, End Shield Parting Plane & Connecting Flange Holes.

CNC Horizontal Boring Machine PAMA is multi-skill machine with wide applications and used for critical machining operations. E.g.- Stator Frames, End Shield, Turbine casings.

BHEL- Hyderabad

MACHINE APPLICATION

GAS TURBINE CASINGSTEAM TURBINE

CASING

TURBO-GENERATOR STATOR FRAME

GAS TURBINE CASING

TURBO-GENERATOR

END-SHIELD

PARTING PLANE HOLES

PARTING PLANE HOLES

CONNECTING FLANGE HOLES

STATOR FRAME

GAS TURBINE OUTER CASING

PARTING PLANE HOLES



BHEL- Hyderabad

PROBLEM DESCRIPTION

Machine was supplied with ISO60 spindle taper and ISO60/BT50 reducer sleeves with pull stud arrangement. Because of this only BT50 holder has to be used.

PAMA CNC horizontal boring machine did not have the facility of pull-stud locking for heavy duty ISO-60 tool holder.

Hence machining was to be carried out at very less cutting parameters, so heavy cuts are not possible.

PROBLEM DESCRIPTION

BT-50 TOOL HOLDERISO-60/BT-50 REDUCERSPINDLE TAPER (ISO-60)

MACHINE SPINDLE

BHEL- Hyderabad

Because of this tool holding system limitation of PAMA CNC Boring Machine:

Only BT-50 holders can be used and heavy cuts are not possible. Maximum Ø250 cutters can be used, but the application requires heavy cuts. Tool holders getting broken when heavy cuts are given . Machine capacity is under-utilized due to poor cutting parameters and tool

holding system.

PROBLEM DESCRIPTION-MILLING

BROKEN HOLDERBT-50 HOLDER

BHEL- Hyderabad

Drilling of holes are done in

many steps for larger diameter holes (More than Ø32 mm holes) by changing drills (Ø32, Ø48, Ø60).

Maximum Ø60mm drills can be used for drilling, for holes more than Ø60mm boring operation is used.

PROBLEM DESCRIPTION-DRILLING

BHEL- Hyderabad

SUGGESTION

After studying the construction features of the machine spindle, ISO60 holder clamping and unclamping system, one new pull stud was designed and got it machined (manufactured) in shop.

BHEL- Hyderabad

DESIGN OF NEW PULL-STUD

New Pull-Stud should have automatic locking & unlocking (Hydraulic) facility for ISO60 holders with internal coolant arrangement.

NEW PULL-STUD

ISO 60 HOLDER

NEW PULL STUDISO-60 HOLDER

BHEL- Hyderabad

DESIGN OF NEW PULL STUD

Ø Ø

Ø

Ø Ø

Ø

Ø

M30

BHEL- Hyderabad

DESIGN OF NEW PULL STUD

BHEL- Hyderabad

PULL STUD SUPPLIED WITH MACHINE PULL STUD MANUFACTURED IN SHOP

NEW PULL STUD

EXISTING METHOD IMPROVED METHOD

BHEL- Hyderabad

ISO60 holders like heavy duty boring heads, the

latest U drill holders ISO60/ABS100 were mounted on to the (with modified pull stud) machine spindle and tested successfully.

Ø107mm holes were drilled directly and even boring operation carried out (with modified pull stud) for Ø250mm and Ø680mm bores.

All the cutters, shoulder mills, side and face cutters and face mill cutters for Ø63mm to Ø550mm were mounted (with modified pull stud) for different operations.

IMPLEMENTATION

BHEL- Hyderabad

IMPLEMENTATION

(Steam Turbine Casing)PARTING PLANE HOLES

IMPLEMENTATION

(125 MW IOCL PARADEEP, Steam Turbine Casing-Parting Plane)

BHEL- Hyderabad

125 MW IOCL PARADEEP, Steam Turbine

CasingParting Plane holes(Ø94, Ø107)

BHEL- Hyderabad

IMPROVEMENT IN TOOLING

IOCL PARADEEP (125MW), STEAM TURBINE CASING, PARTING PLANE HOLES DRILLING (UPPER HALF)

OPERATION

EXISTING PRACTICE IMPROVED METHOD

TOOLS USED No. of Tools

Drilling Time(min)

Setting Time(min)

TOOLS USEDDrilling

Time(min)

Setting Time(min)

Ø94x328mm Deep x14 Holes

Drills-Ø32, Ø48, Ø607

765.33 30.00 Drill- Ø941

153.07 10

Boring- Ø60 to Ø94 (Ø70, Ø80, Ø90, Ø94) 3061.33 40.00 Boring not required 0 0

Ø107 x 278 mm Deep x2 Holes


92.67 30.00 Drill- Ø1071

22.24 10

Boring- Ø60 to Ø107 (Ø70, Ø80, Ø90, Ø100, Ø107) 500.40 50.00 Boring not required 0 0

Ø84 x 175mm Deep x 8Holes


233.33 30.00 Drill -Ø841

46.67 10

Boring -Ø60 to Ø84 (Ø70, Ø80, Ø84) 700.00 30.00 Boring not required 0 0

Ø68 x 125mm Deep x 2 Holes


41.67 30.00 Drill- Ø681

7.81 10

Boring- Ø60 to Ø68 83.33 20.00 Boring not required 0 0

Ø32 x 278mm deep, M100 x 6 x 122mm deep,

CB-Ø107mm x 65mm deep x 4 Holes


148.93 30.00 Drill- Ø94, Ø324

49.92 20

Boring- Ø60 to Ø94 (Ø70, Ø80, Ø90, Ø94) 512.00 40.00 Boring-Ø94 to Ø107 (Ø104, Ø107) 52 20

Ø28 x 175mm deep, M80 x 6 x 127mm Deep, CB-Ø84 x 25mm deep x

10Holes


255.83 30.00 Drill- Ø74, Ø284

77 20

Boring- Ø60 to Ø74 (Ø70, Ø74) CB-Ø74 to Ø84 523.33 30.00 CB- Ø74 to Ø84 100 20

Sub Total 40 6918.17 390.00 12 508.71 120

Total 7308.17 628.71

BHEL- Hyderabad

EXISTING IMPROVED METHOD

Drill Size Speed (RPM) Feed (mm/Min) Drill Size Speed (RPM) Feed (mm/Min)

Drilling

Ø32 200 20 Ø68 500-800 25-35

Ø48 160 20 Ø84 500-800 25-30

Ø60 120 15 Ø94 500-800 25-30

Ø107 500-600 25-30

Boring

Ø70 120 6

Ø80 120 6

Ø90 120 6

Ø100 100 5

Ø107 100 5

IMPROVEMENT IN MACHINING PARAMETERS

BHEL- Hyderabad

BENEFITS (TANGIBLE)

Machine Hourly Rate =Rs. 8571.09 (Taken From Process Planning Dept.)

No. of Gas-Turbine & Steam Turbine casing Machined in year 2012-13 = 5 no.

Earlier Improved Method Saving

Machining Time for each casing 243.61 Hrs. 20.96 Hrs. 222.65 Hrs.

Machining Cost for each casing Rs. 20.88 Lac Rs. 1.80 Lac Rs. 19.08 Lac

Total Machining cost for 4 casing ( In Year 2012-13) Rs. 83.52 Lac Rs. 7.18 Lac Rs. 76.33 Lac

BHEL- Hyderabad

Steam Turbine Casing Parting Plane

Machining

MACHINING TIME ...0

50100150200250

243.61

20.96

EARLIER

MACHINING COST Rs. (...05

10152025

20.88

1.8

EARLIER

BHEL- Hyderabad

This Project was implemented for: 250MW Pipavav 9-FA, Gas Turbine Casings (1st 250MW Gas Turbine

Supplied by BHEL Corporation). 125 MW IOCL Paradeep & 150 MW Hindalco Aditya Steam Turbine

Casing. 270 MW Turbo-Generator Stator Frame Machining. (Manufactured for first time in BHEL Hyderabad)

EASINESS: Mechanical Clamping not required because it provides Hydraulic Clamping.

WIDE APPLICATION : All type of holders can be mounted and heavy cutters can be used. Also, now ISO60/BT50 reducer’s sleeves and ISO60 holder can be mounted directly on spindle.

CYCLE TIME REDUCTION: Cycle time reduced by means of better parameters.

LESS MANUFACTURING LEAD TIME

BENEFITS (INTANGIBLE)

BHEL- Hyderabad

tooling modification of cnc_hbm

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