Shaper MCQ Quiz in मल्याळम - Objective Question with Answer for Shaper - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Explanation:

Shaper

• A shaper is a reciprocating type of machine tool intended primarily to produce horizontal, vertical or inclined flat surfaces.
• The size of the shaper is specified by the maximum length of stroke or cut it makes. The maximum stroke length of the shaper is 900 mm.
• In the shaper, the cutting tool has a reciprocating motion and it cuts only during the forward stroke only. The work is held in a vice bolted to the work table.

On a standard shaper the following operations can be performed:

1. Machining of vertical surfaces
2. Machining of horizontal surfaces
3. Machining of angular surfaces
4. Machining of curved surfaces
5. Machining of irregular surfaces
6. Machining of slots and keyways 

Additional InformationShaping, planing and slotting similarities: 

• Shaping, planning and slotting operations are similar types of machining processes which provide a cutting action as a result of straight-line reciprocating motion between the tool and the work.
• In all the processes single-point cutting tools are used.
• In shaping and planning operations, straight and flat surfaces are created.

Shaping, planing, and slotting differences: 

• In shaping operation, the speed motion is accomplished by moving the cutting tool, while in planning the motion is accomplished by the workpiece.
• Shaping is performed in a machine tool called shaper whereas the machine tool for planning is called a planer. 
• Slotting process is identical to shaping except that the motion of the ram is vertical instead of horizontal.

Explanation:

The principal parts of a shaper are

Base: It consists of a heavy robust cast-iron structure that supports all the other parts of the machine.

Column: It acts as a housing for the electrical circuits and operating mechanism of a shaper. It also acts as a support for other parts of the machine, such as ram, cross-rail, tool heads, etc.

Crass-rail: It is a heavy cast iron body attached to the column of a shaper machine. It is used for two purposes-for elevating the table and for cross-traverse of the table. Part B in the question figure.

Table: It is a box-type construction with T-slots cut on it to hold the vice and jobs. It holds and supports the workpiece during operations. It can be moved horizontally by a cross-rail mechanism to provide feed to the workpiece.

Ram: It is the reciprocating part of the shaper and carries the shaper head in front of it. The reciprocating motion of the ram takes place on accurately machined guideways on the top of the column. It gets its drive from the quick return mechanism, which is fitted inside the column to change its position relative to the job. Part A in the question figure.

Tool head: The tool head of a shaper is used for holding the tool rigidly. It also provides vertical and angular feed movement of the tool and allows the tool to lift automatically to provide relief during its idle or return stroke.

Shaper head: It consists of a tool slide, tool post and clapper box and is clamped firmly to the front of the ram. It has a vertical feed screw for the vertical movement of the tool. The vertical movement can be measured accurately by means of a micrometre dial near the handle. 

Explanation:

Shaper Machine:

• In a shaper, the rotary movement of the drive is converted into a reciprocating movement.
• It is done by the mechanism contained within the column of the machine.
• The ram holding the tool makes the reciprocating movement. In a standard shaper, metal is cut in the forward cutting stroke, while the return stroke goes idle and no metal is cut during this period. To reduce the full machining time it is important to reduce the time taken by the return stroke.
• The reciprocating movement of the ram and the quick return mechanism of the machine is usually obtained by following the four types of shaper machine mechanisms.

1. Crank and slotted link mechanism.
2. Whitworth's quick mechanism.
3. Hydraulic shaper mechanism.
4. Automatic table feed mechanism.

Automatic table feed mechanism:

The automatic feed mechanism of the table is very simple. This is done by rotating a ratchet wheel, mounted at the crossfeed screw. This enables a corresponding equal rotation of the crossfeed screw after each stroke.

Arrangements of Parts:

It consists of a slotted disc, which carries a T-slot, as shown in the figure. In this slot, an adjustable pin is fitted and to this is attached a connecting rod. The other end of the connecting rod is attached to the lower end of the ratchet arm of the pawl mechanism.

The ratchet arm swings about the screw C, and at its upper end carries a spring-loaded pawl, as shown.

Working:

• The lower end of the pawl is bevelled on one side. This arrangement helps the power feed to operate in either direction, but the same should be set to operate during the return stroke only.
• Variation in the feed can be provided by varying the distance R between the disc centre and the centre of the adjustable pin. The larger the said distance greater will be the feed and vice versa.
• The amount of feed to be given depends upon the type of finish required on the job.
• For rough machining, heavier cuts are employed, and thus, a coarse feed is needed. Against this, a finer feed is employed in finishing operations.
• The slotted disc at its back carries a spur gear which is driven by the bull gear. As the disc rotates through this gear the adjustable pin, being eccentric with the disc centre.
• This causes the connecting rod to reciprocate. This, in turn, makes the rocker arm to swing about the screw C to move the pawl over one or more teeth. Thus transmit an intermittent motion to the crossfeed screw which moves the table.

Concept:

For shaper machine

Total time taken \(= \frac{{L.D\left( {1 + m} \right)}}{{Velocity}}\) 

Where L = Length of cut, D = No. of double stroke \(= \frac{{Width}}{{Feed}}\)

\(m = \frac{{Time\;of\;return}}{{Time\;of\;cutting}} = \frac{{Velocity\;of\;cutting}}{{Velocity\;of\;return}}\)

\(T = \frac{{LW\left( {1\; + \;m} \right)}}{{f\; \times \;v}}\)

Calculation:

For Machine S1

\({T_1} = \frac{{L{W_1}\left( {1 + m} \right)}}{{{f_1} \times v}}\)

W1 & f1 are width & feed for machine S1 other parameters are constant, then, 

For Machine S₂

W₂ = 1.10 W₁

f₂ = 0.90 f₁

\(\therefore {T_2} = \frac{{L{W_2}\left( {1 + m} \right)}}{{{f_2} \times v}} = \frac{{1.10{W_1} \times L\left( {1 + m} \right)}}{{0.9{f_1} \times v}} = 1.22\frac{{L{W_1}\left( {1\; + \;m} \right)}}{{{f_1}\; \times \;v}}\;\)

T₂ = 1.22 T₁

\(\therefore \frac{{{T_1}}}{{{T_2}}} = 0.8181\)

Explanation:

Slotting Process:

• Slotting is a machining process in which a vertical tool reciprocates up and down to cut slots, grooves, or other profiles in a workpiece. The primary motion is the reciprocation of the tool.

Let's understand the slotting process in detail:

Working Principle:

• In the slotting process, the tool moves vertically up and down, and the workpiece is fed into the cutting tool.
• The cutting action occurs during the downward stroke of the tool, and the tool returns to its original position in the upward stroke without cutting.

Key Components:

• Tool: The cutting tool, which is usually single-point, reciprocates vertically.
• Workpiece: The material being machined, which is fed into the tool to create the desired slot or groove.

Important Points

• The tool in a slotting machine reciprocates vertically, which is the distinguishing feature of this process.
• The workpiece is usually stationary during the vertical movement of the tool, and it is fed horizontally or vertically as required to complete the machining operation.

Additional Information

Applications of Slotting Machine:

• Creating slots, grooves, and keyways in various components.
• Machining internal and external gears.
• Forming irregular shapes and intricate profiles in the workpiece.

Advantages:

• Capable of handling large and bulky workpieces.
• Suitable for producing precise and accurate slots and grooves.

Disadvantages:

• Lower production rate compared to other machining processes like milling.
• Limited to specific applications such as slotting and keyway cutting.

Explanation:

• Shaper is a reciprocating type of machine tool in which the ram moves the cutting tool backwards and forwards in a straight line.
• These surfaces may be horizontal, vertical, or inclined. In general, the shaper can produce any surface composed of straight-line elements.
• A shaper is used to generate flat (plane) surfaces by means of a single-point cutting tool similar to a lathe tool.

Shaper:

• Shaper is a reciprocating type of machine tool in which the ram moves the cutting tool backwards and forwards in a straight line
• The work-piece is rigidly held in a vice or clamped directly on the table; It is intended primarily to produce flat surfaces
   

Explanation:

Shaper Machine:

• Shaper Machine is a reciprocating type of production machine in which the single point cutting tools are attached and the workpiece is fixed moving forward the tool cuts the workpiece and in return, there is no cut on the workpiece and used for producing flat surfaces.

Shaper Machine consists of the following parts:

• Base
• Column
• Table
• Cross rail
• Ram
• Clapper Box
• Elevating Screw

Quick return mechanism:

• In a shaper machine, a quick return mechanism is used to achieve a backward stroke faster than the forward cutting stroke.
• A quick return mechanism is an apparatus to produce a reciprocating motion in which the time taken for travel in the return stroke is less than in the forward stroke.
• It is driven by a circular motion source (typically a motor of some sort) and uses a system of links with three turning pairs and a sliding pair.
• A quick-return mechanism is a subclass of a slider-crank linkage, with an offset crank.
• Quick return is a common feature of tools in which the action is performed in only one direction of the stroke, such as shapers and powered saws because it allows less time to be spent on returning the tool to its initial position.

Shaper Machine Working:

• The shaper works on the principle of the Quick return motion mechanism.
• The tool is held and the workpiece is fixed over the table.
• When we switch on the power the ram reciprocates with respect to the table which means the cutting tool cuts workpiece material in the forward direction and when moving return there is no cut.
• The cutting process takes place at a low speed of ram and the return stroke takes place at a high speed.
• With the use of a hand transverse wheel, we can do up and down the table.

Explanation:

Shaper:

• A shaper is a reciprocating type of machine tool intended primarily to produce horizontal, vertical or inclined flat surfaces.
• The size of the shaper is specified by the maximum length of stroke or cut it makes. The maximum stroke length of the shaper is 900 mm.
• In the shaper, the cutting tool has a reciprocating motion and it cuts only during the forward stroke only. The work is held in a vice bolted to the work table.

On a standard shaper the following operations can be performed:

1. Machining of vertical surfaces
2. Machining of horizontal surfaces
3. Machining of angular surfaces
4. Machining of curved surfaces
5. Machining of irregular surfaces
6. Machining of slots and keyways 

Additional Information

Shaping, Planning and Slotting similarities: 

• Shaping, planning and slotting operations are similar types of machining processes which provide a cutting action as a result of straight-line reciprocating motion between the tool and the work.
• In all the processes single-point cutting tools are used.
• In shaping and planning operations, straight and flat surfaces are created.

Shaping, planning, and slotting differences: 

• In shaping operation, the speed motion is accomplished by moving the cutting tool, while in planning the motion is accomplished by the workpiece.
• Shaping is performed in a machine tool called shaper whereas the machine tool for planning is called a planer. 
• Slotting process is identical to shaping except that the motion of the ram is vertical instead of horizontal.

Explanation:

Shaper:

• The shaper machine is a reciprocating type of machine basically used for producing horizontal, vertical, or flat surfaces.
• The shaper holds the single-point cutting tool in ram and the workpiece is fixed in the table. 
• During the return stroke, No metal is cut.

Working principle of shaper:

• The job is rigidly fixed on the machine table.
• The single-point cutting tool held properly in the tool post is mounted on a reciprocating ram.
• The reciprocating motion of the ram is obtained by a quick return motion mechanism.

Construction of shaper:

• The main parts of the Shaper machine are the Base, Body (Pillar, Frame, Column), Cross rail, Ram, and tool head (Tool Post, Tool Slide, Clamper Box Block).

Ram:

• It is the main part of the shaper machine. It holds the tool and provides reciprocating motion to it.
• It is made of cast iron and moves over ways on columns. It is attached by the rocker arm which provides its motion in the crank-driven machine and if the machine is hydraulic driven it is attached by 

Tool head:

• It is situated at the front of the ram. Its main function is to hold the cutting tool. The tool can be adjusted on it by some of the clamps.

Table:

• It is the metal body attached to the frame. Its main function is to hold the workpiece and vice over it. It has two T slots which are used to clamp the vice and workpiece over it.

Clapper box:

• It carries the tool holder.
• The main function of the clapper box is to provide clearance for tools in return stock.
• It prevents the cutting edge from dragging the work piece while returning stock and prevents tool wear.

Column:

• The column is attached to the base. It provides housing for the crank slider mechanism. The slideways are attached upper section of a column which provides a path for ram motion.

Cross ways:

• It consists of vertical and horizontal tables sideways which allows the motion of the table.
• It is attached with some cross movement mechanism. Stroke adjuster: It is attached below the table. It is used to control the stroke length which further controls the ram movement.

Table supports:

• These are attached front side of the table and used to support the weight of the table during working.

Concept:

Approach and over-travel are provided on the cutting stroke and return stroke.

Cutting Stroke Time (CST):

\(CST=\frac{Length\;+\;Approach\;+\;Overtravel}{Cutting\;velocity}\)

Idle Stroke Time (IST):

\(IST=\frac{Length\;+\;Total\;Allowance}{Return\;velocity}\)

Total Time per cycle = CST + IST

Feed is in the opposite direction of cutting.

No of cycles required = \(\frac{Width\;+\;Total\;Allowance}{Feed/cycle}\)

Machining Time = No. of cycles × Time per cycle

Calculation:

Given:

Length × Breadth × Thickness = 450 mm × 230 mm × 60 mm

V_c = 15 m/min, V_r = 30 m/min and feed per cycle = 10 mm

Approach = Overtravel = 25 mm

Cutting Stroke Time (CST):

\(CST=\frac{Length\;+\;Approach\;+\;Overtravel}{Cutting\;velocity}\)

\(CST=\frac{(450\;+\;25\;+\;25)× 60}{1000\;×\;15}= 2\;sec\)

Idle Stroke Time (IST):

\(IST=\frac{Length\;+\;Total\;Allowance}{Return\;velocity}\)

\(IST=\frac{(450\;+\;25\;+\;25)\;× \;60}{1000\;×\;30}=1\;sec\)

Total time per cycle = CST + IST = 3 sec.

Number of cycle required:

\(\frac{Width\;}{Feed/cycle}\)

\(\frac{230}{10}=23\;cycle\)

Machining Time = No. of cycle × Time per cycle

Machining Time = 23 × 3 = 69 sec