WELCOME TO ALL

SPECIALLY WISHES TO ALL

CONTOUR ATTACHMENT FOR LATHE

NEED FOR ATTACHMENT In recent years, new fabrication techniques

have been developed to satisfy the technological demands. Moreover, emphasis is stressed on attachments. Attachments are

used in various fields and machines depending upon the needs to be fulfilled and

mode of operations. An attachment eliminates the purchasing of a new unit which serves the same purpose. For example, a lathe occupies a place opposite to that of a milling machine,

the ten machines mainly

SYNOPSIS A concave attachment is a versatile one to cut concave-

convex profiles. A set of rotating plates have T-slots for the T-bolts that hold the boring bar. These plates are rotated by a train of gears. The bar is held roughly yet free enough to rotate. When the tool is built, the boring bar is first clamped with both pivots at lead centre. So, the tool describes a zero radius when the crank is turned.

At this time, one set up pin hole is drilled in each of the rotating, plates, as indicated so that the pin touches the boring bar. Then to set the tool, for a desired radius, it is merely necessary to place a piece of flat stock the same thickness as the desired radius between the bar and the set up pins while securing the bar in position. At this point, data the flat stock and set up pin can be removed.

INTRODUCTION The concave attachment is fixed to the

carriage of the lathe. The compound rest that is locked solid with its base is removed and the attachment is fixed on the cross lied of the carriage with its axis parallel to the lathe bed.

The work is secured rigidly in a chuck. By the concave-convex movement of the boring bar, the material is being removed. This attachment is used to produce contour profiles and round balls.

NAME OF THE PARTS WORM GEAR WORM SHAFT SPUR GEARS BASE PLATES BORING BAR SHAFTS HANDLE TOOL HOLDER

WORKING PRINCIPLE The worm wheel is rotated with the help of a worm

shaft. Rotating plates with T-slots that hold the boring are screwed to the worm wheel. The worm wheel in turn is screwed to its base with a simple gear train. The rotary motion is imported to the blank through two spur gears and an intermediate gear namely “Idler Gear”.

The idler gear serves to keep the rotation of rotating plates in the same direction. The worm shaft is rotated is clockwise direction, the boring bar machines a contour profile in the clockwise direction and vice versa. Thus a concave-convex profile is machined by boring bar by simultaneous engagement of the two plates.

DRAWING FOR CONTOUR ATTACHMENT FOR LATHE

DRAWING FOR CONTOUR ATTACHMENT FOR LATHE

WORK DONE FOR THE PROJECT

WORM GEAR• The gear is cast iron material• The worm gear has the following

dimensions• Outer dia = 50mm• No.of teeth = 39• Module = 1.25• Inner diameter = 15mm

DIAGRAM

SPUR GEARSo The gear is cast iron material o Outer diameter = 98mmo Inner diameter =15mmo Module = 1.25o No.of teeth =76

SMALL GEAR o Outer diameter = 50mmo Inner diameter =15mmo Module = 1.25o No.of teeth =39

DIAGRAM

WORM SHAFT

This material is mild steel This material dimensions given below Length = 55mm Diameter = 25mm Pitch = 1.25

DIAGRAM

SHAFTS The shaft is mild steel No. of shaft = 7nos Total Length = 300mm Big diameter = 20mm Small diameter = 15mm

BASE PLATES The base plate is M.S No. of plate = 2nos Length = 286mm Thickness = 10mm Width = 120mm

WORK HAS TO BE DONE FOR THE PROJECT

Purchasing the bolts and nuts Slotting the gears Designing the boring bar Collecting the tool Design the handleDrilling & tapping for shaft Drilling the base plate welding Hand holder to base plate Assembling the total parts

ADVANTAGES

The unit is compact in sizeLess maintenance is essentialThe unit gives long life with proper alignment of gearsJobs can be easily handled in this unit

APPLICATIONS Concave and convex profiles of

desired radius can be easily turned Round balls can be produced