Shaper

Experiment No: 03 Name of the Experiment: “Study and Operation of Shaper Machine” Date of Performance: 23.04.2015 Date of Submission: 30.04.2015

Submitted By, Name: Zakia Sultana Ritu Reg no: 2013331045 Group name in workshop(IPE 108) -“ D” Department of computer science & engineering

Introduction:

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Introduction: The shaper is a reciprocating type of machine tool intended primarily to produce flat surfaces. These surfaces may be horizontal, vertical, or inclined. In general the shaper can produce any surface compost of straight line element. Modern shaper can generate contoured surface. Shapers were very common in industrial production from the mid-19th century through the mid-20th. In current industrial practice, shapers have been largely superseded by other machine tools (especially of the CNC type), including milling machines, grinding machines, and broaching machines. But the basic function of a shaper is still sound; tooling for them is minimal and very cheap to reproduce; and they are simple and robust in construction, making their repair and upkeep easily achievable. Thus they are still popular in many machine shops, from jobbing shops or repair shops to tool and die shops, where only one or a few pieces are required to be produced and the alternative methods are cost or tooling-intensive. A shaper is a type of machine tool that uses linear relative motion between the work piece and a single-point cutting tool to machine a linear tool path. Its cut is analogous to that of a lathe, except that it is (archetypal) linear instead of helical. (Adding axes of motion can yield helical tool paths, as also done in helical planning.) A shaper is analogous to a planer, but smaller, and with the cutter riding a ram that moves above a stationary work piece, rather than the entire workpiece moving beneath the cutter. The ram is moved back and forth typically by a crank inside the column; actuated shapers also exist.

Tools: Shaper machine; components of Shaper machine are-

The main parts are2|Page

 Base: The base is a heavy cast iron casting which is fixed to the shop floor. It supports the body frame and the entire load of the machine. The base absorbs and withstands vibrations and other forces which are likely to be induced during the shaping operations.  Body (Pillar, Frame, and Column): It is mounted on the base and houses the drive mechanism compressing the main drives, the gear box and the quick return mechanism for the ram movement. The top of the body provides guide ways for the ram and its front provides the guide ways for the cross rail.  Cross rail: The cross rail is mounted on the front of the body frame and can be moved up and down. The vertical movement of the cross rail permits jobs of different heights to be accommodated below the tool. Sliding along the cross rail is a saddle which carries the work table.  Ram and tool head: The ram is driven back and forth in its slides by the slotted link mechanism. The back and forth movement of ram is called stroke and it can be adjusted according to the length of the workpiece to be-machined.

Operations: Types of Shapers- There are different types of Shaper machines. We can classify them as given belowAccording to the position and travel of the arm  Horizontal type  Vertical type and  Traveling-head type According to the type of design of the table  Standard shaper and  Universal shaper According to the type of cutting stroke  Push type and  Pull \ Draw type According to the type of mechanism used  Crank type  Geared type and  Hydraulic type

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Among all the Shapers Crank shaper is the most common. This is the most common type of shaper where a single point cutting tool is given a reciprocation motion equal to the length of the stroke desired while the work is clamped in position on an adjustable table. General operation of Shaper machine:

The workpiece mounts on a rigid, box-shaped table in front of the machine. The height of the table can be adjusted to suit this workpiece, and the table can traverse sideways underneath the reciprocating tool, which is mounted on the ram. Table motion may be controlled manually, but is usually advanced by automatic feed mechanism acting on the feed screw. The ram slides back and forth above the work. At the front end of the ram is a vertical tool slide that may be adjusted to either side of the vertical plane along the stroke axis. This tool-slide holds the clapper box and toolpost, from which the tool can be positioned to cut a straight, flat surface on the top of the workpiece. The tool-slide permits feeding the tool downwards to deepen a cut. This adjustability, coupled with the use of specialized cutters and tool holders, enable the operator to cut internal and external gear tooth profiles, splices, dovetails, and keyways. The ram is adjustable for stroke and, due to the geometry of the linkage, it moves faster on the return (noncutting) stroke than on the forward, cutting stroke. This action is via a slotted link or Whitworth link. Cutting Time Calculation and Quick Return Mechanism: Let L = the length of the stroke in mm B = the breadth of the work material in mm s = the feed expressed in mm / double stroke m = the ratio of return time to cutting time v = the cutting speed in meter / min Time taken to complete one double stroke =

L 1000 × v

(l+m)

Total numbers of double strokes required to B/s complete the cut.

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 Total time taken to complete the cut, =

L× B(l+ m) 1000 × v × s

where, m = (Return stock time) / (Cutting stroke

time) Shaper machine uses quick return mechanism to work more accurately. Here the ratio of cutting stroke and return stroke is 3:2. Cutting stroke : return stroke = 3 : 2

Discussion: We learned a lot of things from today’s experiment. Such as- Clapper box is hinged at the top to permit the tool to ride over the work on the return stroke. The cutting action of the shaper is intermittent—the tool moves slowly on the cutting stroke and return quickly. It must be remembered that the rpm of the crank gear is unchanging once it has been set. The ratio between the forward and the return strokes is approximately 1 to 1.5 or 2 to 3, varying slightly with the length of the stroke. To obtain the correct number of strokes per minute, multiply the cutting speed by 7 and divided the product by the length of the stroke in inches. Also the tool head of the shaper should be set at the same angle as that of the dovetail to be cut. When dovetail bearing such as those shown in fig (Dovetail bearing) are to be cut, the work should not be distributed in shaping the angular and flat surfaces of the dovetail. The horizontal surfaces should be machined before completing the angular surface. A right-hand tool and left-hand tool are used to machine the angular sides, one at a time, as shown in fig (Shaping a dovetail with a right-hand and left-hand tool holder). Both a roughing and finishing tool should be used if considerable stroke is to be removed. In using two tools and moving the tool head from one side of the centre line to the other, great care must be exercised; if there is any variation in the angular setting of the head, a variation in the angular sides of the dovetail will result. In overall appearance there is very little difference between the hydraulic and crank shaper. The ram of the crank shaper gets its movement from the rocker arm, which is caused to move by the crank pin attached to the bull gear. The ram of the hydraulic shaper is moved by oil pressure, which is developed by a pump driven by an electric motor. And a planer is designed with a stationary housing for holding tool head and a table with a reciprocating movement for holding the work; thus the work is moved against the cutting tool. With the shaper, the work is held stationary and the cutting tool is moved across the work.

References:    

https://mechmania.wordpress.com/2008/09/05/quick-return-crank-mechanism/ http://en.wikipedia.org/wiki/Shaper https://www.scribd.com groups.google.com

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