The Line Boring Machine [PDF]

Citation preview

DIVINE WORD SCHOOLOF SEMIRARA ISLAND, INC Semirara Island, Caluya, Antique



DEPARTMENT OF TECH-VOC MACHINING SECTION



LINE BORING MACHINE Prepared by: Machining Instructors: Romel S. Ambungan Sr. Jinky L. Lavega



Date prepared: March 15, 2020



LINE BORING MACHINE Module Description: Lectures with demonstration and illustration related to the machine and concept in a new machining. Topics to be discussed include applications, capabilities, performing its operation from simple to complex procedure and the complexity of the machine. Duration: 35hrs Objectives: At the end of this module the trainees/student should be able to:      



Define a Line Boring Machine and its operating procedure. Categorize common application of Line Boring Machine into the correct usage of attachments. Identify the component of Line Boring Machine and describe the operation. Understand the structure and performance of Line Boring Machine. Measure roundness and concentricity of the bores using a variety of tools. Operate Line Boring Machine and perform simple and complex projects.



Module Outline: I. II.



III. IV. V. VI.



Line Boring Machine Description Set up Procedure a. Feed Unit Closed Coupled b. Remote Mounted Cutting Tools Feed Rate Mechanism Power Options Common Application



SAFETY INSTRUCTIONS 1. 2. 3. 4. 5.



Always keep the guards in place, and in working order. Remove adjusting keys and wrenches. Keep the working area clean. Use the right tool. Wear proper apparel  Don’t wear loose clothing  Gloves  Neckties  Rings  Bracelets  Non-slip footwear is recommended.  Wear protective hair covering to contain long hair. It may get caught in moving parts. 6. Always use safety glasses when operating the machine 7. Secure work using clamps or vise, and be sure all guards are in place before operating the equipment. 8. Don’t over reach. Keep proper footing and balance at all times. 9. Maintain tools with care. 10. Disconnect power from tools before operating. 11. Make sure the switch is in the off position before plugging. 12. Check alignment, binding or breakage of moving parts or any other conditions which may affect operations. 13. Never leave the tool unattended while running. 14. Before starting up, recheck to make certain all holding screws are tight 15. Always stop the motor and disconnect the power source, before making any adjustments. 16. All visitors should keep safe distance 17. Don’t force-feed boring head. Allow the boring machine to apply the proper feed rate.



THE LINE BORING MACHINE Line boring is a very universal machine, it is the process of enlarging a hole that has already been drilled or cast. It is the internal diameter counterpart to turning, which involves cutting external diameters. Line boring is carried out using one or more cutting tools held within a boring head. The process achieves greater accuracy in cutting internal diameters, and it can even be used to create tapered holes. Line boring is an especially valuable service in the mining industry. Line boring can be used to return old or worn with specified repair procedures. Worn pin bores, tunnel bores, axle pivots, and bearing housings are all examples of problems that can be addressed with line boring.



LINE BORING



SET-UP AND OPERATION A Fast Six- Step Process Setup of Line Boring Machine is quick and easy, the three main procedure of quick setup are:  Setup cones to roughly center the bar in the bore  Spherical mounts that can be quick tack-welded in place.  Quick mount rotational drive unit, attaches to spherical mount in seconds.



1. Slide the bar through the two holes to be bored and roughly center it with the set-up cones. The set-up cones are forced into the bore with the clamp ring jacking screw and locked onto the bar with a set screw.



2. Slide on spherical mounts with tack weld plates, and tack them to the workpiece. These mounts have spherical bearings so they can be mounted up to 5 degrees put of perpendicular alignment.



3. Remove the set-up cones and replace the bar. The set-up cones will adequately center the bar, or need to move the centerline of the bore slightly. Final centering adjustments are made with the jacking screws.



4. Slide the rotational drive onto the bar. Firmly push it onto the spherical mount, and lock it in place with one bolt. Tighten the rear clamping collar enough to be snug but so the bar can slide through it.



5. The axial feed unit is slipped onto the bar and the leadscrew is screwed into the pocket on the rotational drive unit. Tightening two clamping collars the axial feed unit to the bar.



6. Insert a properly ground tool bit into the hole in the bar, adjust for depth of cut, and lock in place with the set screw. Connect to the power source.



FEED UNIT CLOSE COUPLED SET-UP



Typical set-up with Feed Unit Close Coupled 1. Establish the best position for the boring head either at the center or on the ends of the boring bar. Select the variable feed unit for close coupled to the boring head or remotely locate the position for limited space.



2. Determine required boring bar length. As the boring head is centrally mounted, the boring bar has to protrude from the outer set of bores by at least 300mm. this allows sufficient length for attachment of the support bearings and travel of the boring bar while feeding.



3. Establish the best position to mount the support bearings and then select the appropriate size .the backing plates for the support bearings and machine mounting bracket may then welded to the workpiece. 4. Weld M20 threaded rods about 100mm long to the center of each backing plate (backing plates are made to suit individual set up requirements). Cut to size and weld in suitable position on the workpiece.



5. As facing is required, the boring bar supports bearings to be mounted the width of the facing heads plus cutting tool away from the workpiece. If facing is not required then threaded rods can be welded directly to the bore face. FACE HEADS



6. Bolt the self-aligning 90 degrees support the bearings to the backing plate using the M20 stud and clamping the plate to secure them in place. The four jacking bolts are then used to square up the supports to the face of the bore.



7. Slide the boring 8. Align boring by tapping two outer



bar into position. the bar the



supports until the desired positions of the bore which will allow more accurate positioning. Centralising cones is used as a means of setting up. Clamp the two outer support bearings firmly.



Using Centralizing Cones 9. Clamp the centre support bearing and machine mounting bracket and then check the boring bar slides freely. The boring bar must slide freely within all the support bearings.



10. Fit the boring head to the center of the boring bar by sliding back the boring head, support bearing still engaged with the boring head position slide the boring bar back through the hollow spindle of the boring head.



11. Slide the boring head up to the spherical seat and secure with the quick lock ring. This is done by locating the pins on the boring head in the holes in the quick lock ring, rotate the quick lock ring until it stops and tighten the cap screw located in the quick lock ring periphery.



12. Fit the appropriate tool holder and cutting tool, for this particular situation it is possible to machine two bores simultaneously by mounting two cutting tools to the boring bar.



13. Adjust the tool radially to give a minimum clean up cut. In cases where bores are badly worn, several cuts may be necessary to achieve clean up.



14. Once all set up procedures have been carried out and checked. Ensure that no damage or injury can result from rotation of the boring bar and cutting tool.



.  Power pack connected and hydraulic hoses attached, turn on machine.  Check that the direction of rotation of the electric motor is correct.  Individual power outlets have different wirings. 15. Hand-feed the tool into the bore until enough has been machined to enable correct measurement.



16. Retract the cutting tool using the hand-feed and check with an internal micrometer from the bore inside diameter to the boring bar. The correct bore diameter is twice the micrometer reading plus the boring bar diameter.



An internal caliper is used to measure the bore diameter.



17. Adjust the cutting tool radially to suit the required diameter and then machine bore using the automatic feed. Adjustment is most accurately achieved using a dial indicator measuring directly off the front or rear of the cutting tool itself and with the cutting tool clamping screw, just lightly tightened, then the cutting tool tapped out the desired amount.



18. Once the boring operation has been completed, remove the cutting tool holder and fit the automatic feed facing attachment for facing if required.



TYPICAL SET-UP PROCEDURE (Feed Unit Remote Mounted)



1. This set-up may be utilized in situations where there is insufficient space to enable close coupling of the variable feed unit to the boring head. 2. The variable feed unit may be mounted at any distance from the boring head, the only limitation being the length of the boring bar to which it is fitted. 3. The only additional requirement when utilizing the variable feed unit remotely is the addition of a reaction plate to which the socket that anchors the feed screw may be secured. a. This unit is essentially a fixed point from which the variable feed unit may impart lateral movement to the boring bar.



b. This reaction plate may be a part of the work piece itself, or any other suitable stationary object.



CUTTING TOOL HOLDER BORE RANGE: The following table serves as a guide to the cutting tool holders and cutting tools used to machine a particular bore diameter range: BORE RANGE



NUMBER



DESCRITION



32 – 52mm 51 – 17mm 117 – 162mm 162 – 212mm 212 – 252mm 252 – 332mm



Option 1 1 2 4 5 6



31.75mm Boring Bar 50.80 Boring Bar Tool Holder 1 Tool Holder 2 Tool Holder 3 Tool Holder 4



CUTTING TOOLS C1 C2 C3 C3 C3 or C5 C3 or C5



LARGE BORE TOOL HOLDER (Optional): BORE RANGE



NUMBER



DESCRITION



332 – 480mm 480 – 630mm 630 – 780mm 780 – 930mm



Option – 2 Option – 3 Option – 4 Option – 5



Bar 1 Bar 2 Bar 3 Bar 4



CUTTING TOOLS C3 to C6 C3 to C6 C3 to C6 C3 to C6



LEGEND (CUTTING TOOLS) C1 C2 C3 C4 C5 C6



6mm Square HSS Cutting Tool 12mm Square HSS Cutting Tool 12mm Square HSS Cutting Tool 20mm Square HSS Cutting Tool 12mm Square Braised Carbide Cutting Tool 20mm Square Carbide Insert Tool Holder



SPEED RANGES: The rotational speed of the boring bar is infinitely variable from 0 to 210 rpm in either direction. Rotational speed adjusted via the wireless hand-held remote (1off). It is recommended that spare AA batteries are kept.



CUTTING TOOL ADJUSTMENT: Adjustment is most accurately achieved by using a dial indicator measuring directly off the front or rear of the cutting tool itself and with the cutting tool clamping screws, just lightly tightened, the cutting tool tapped out the desired amount. FEED MECHANISM: Manual Feed:  Manual feed may be achieved by using either of the two hand hand-wheels. One is fitted to the boring head and the other to the variable feed unit.  When using the hand-wheel fitted to the variable feed unit. Ensure that the feed screw is clamped by the knurled knob located under the handle located on the boring head. Feed in either direction is then achieved by rotation of the hand-wheel.  When using the hand-wheel fitted to the boring head. First unclamp the knurled knob under this hand wheel. Then engage the plunger which is located directly below the hand-wheel on the variable feed unit.



AUTOMATIC FEED:  Ensure that the feed screw is clamped by the knurled knob located under the handle located on the boring head.  Feed is activated whilst the machine is rotating by engaging the feed lever in either direction. Feed direction is dictated by the position of the feed lever. If the feed lever is moved toward the boring head the tool will move in this direction. Conversely, if the lever is moved away from the boring head then the tool will move in the other direction/  Rate of feed is determined by the amount that the feed lever is rotated. Five individual rates are available and the feed lever indexes through these in a number of steps. Feed increases proportionally to the amount of rotation, once engaged.  The variable feed unit is designed such that should a collision or overload situation occur, feed will cease.



ELIMINATING VIBRATIONS: If vibration occurs while machining with the portable line boring machine, any one, or all of the following are possible cures:  Alter the cutting speed via the potentiometer dial on the hand-held remote.  Alter the feed rate by using the feed lever.  Reduce the cut depth.  Eliminate all clearances via backlash adjustment devices.  Check that all mounts are secure  Sharpen the cutting tool and produce a small wear land on the cutting edge via an oil stone in order to suppress high frequency chatter.  Alter the rake angle of the cutting tool.  Change the structural response of the system by adding or moving boring bar support bearings. COMMON APPLICATIONS Line boring machines are used on a wide range of projects, with some common examples including:



       



Excavator buckets Transfer gearbox housings Stern tubes and rudder bores in the shipbuilding industry Drive shaft housing boring A-frame supports Hinge pins Gearboxes Turbine casings in the power generation industry In addition to machining parallel bores, line boring machines can also be used for tapering holes and for machining the outside face of the work piece using a facing head.



HYDRAULIC



POWER PACK



Operating Temperature: Overheating the oil will have the following detrimental effects:  The decreased oil viscosity at high temperatures significantly reduces motor and pump efficiencies.  Hardening of seal occurs which will result in leakage when the unit is next use.  In extreme cases a complete melt down of the hydraulic circuit mat occur. Hence the power pack temperature MUST BE KEPT BELOW 65° C OIL TYPE: Use H.L.P> mineral oils that comply with ISO 46. The recommended minimum oil viscosity =46.3cSt (mm²/s). AWS 46 is a typical example of oil that complies with the above requirements. OIL CHANGE:



It is recommended that the oil be changed every 2000 hours of operation. This is, however, highly dependent upon whether the oil has been overheated or has become contaminated and a regular visual inspection should be performed, a darkening of the oil would indicate overheating and the oil should be immediately be changed. OIL FILTER CHANGE: The first oil filter change should occur after 50 hours of operation and every 500 hours thereafter. Both the return and pressure filter elements should be changed.



AIR



BREATH FILTER:



This should be cleaned at each oil filter by washing in a solvent and then drying with compressed air. MAXIMUM WORKING PRESSURE: The maximum pressure has been preset to match the installed power of the electric motor and is non-adjustable.  Maximum working pressure:140bar  Pressure relief valve set pressure:160bar



COULPINGS: All quick release couplings must be cleaned before engaging to ensure that no dirt enters into the hydraulic system. When disconnected the plastic caps must be placed on each of the couplings.



LUBRICATION Storage: All components should be cleaned and lightly oiled before storage to prevent corrosion. Support Bearings: The self-aligning bearings should be well lubricated with grease before starting the machine and then grease applied via a grease gun after each



hour that the machine is operating. This will help maintain a seal between the bearing and the boring bar, and prevent foreign particles entering. Boring Bars: The boring bars should be lightly oiled before and after use. If any score marks develop on the surface of the boring bar they should be smoothed with an oilstone. Surfaces: Before use the feed screw and nut component surfaces should be well cleaned and then given a light coat of grease. Grease nipples: Grease should be injected into all nipples after 12 hours of use. Support bearings need to be greased after each hour of machining.



BACKLASH ADJUSTMENT All excessive backlashes that may occur in the feed mechanism must be adjusted out. This adjustment is possible at two points: Feed Screw-Feed Nut Backlash: Adjust out via the knurled wear compensation nut. This nut is attached to the main feed nut and is locked in position via a grub screw with a small bronze plug at the end of the screw to prevent it damaging the mating thread. This grub screw must be backed off to allow adjustment then re-tightened.



Bearing End Float on the Variable Feed Unit: Adjust this out via the pin driven nut fitted to the variable feed unit clamping sleeve. The pin driven nut is locked in position via a grub screw with a small bronze plug at the end of the screw to prevent it damaging the mating thread. This grub screw must be backed off to allow adjustment the retightened.