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Topic: Milling MachineReporting students: Code1.Luu HoangThang 10912962.Nguyen Thanh Sang 10912833.Dang Van Thanh 10912954.Le Van Nhan 10912725.Nguyen Tuong Lai 1091266

Can Tho UniversityCollege of Technology

Subject: English for Mechatronics

Supervisor:Vo Minh Tri, DSc

Milling Machine

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Main Contents

Introduction1

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Type of milling machines

Computer controlled machine systems

Milling machine attachments and accessories

Block DiagramMilling Machine

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IntroductionMilling Machine

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Modern milling machines look much the same as they did 25 years ago. However, they now must cut super alloys, titanium, and high tensile steels to closer tolerances and at faster rates then previously. To handle these requirements, the new milling machines provide higher horsepower, greater stiffness, and wider speed and speed ranges than before. In addition, more accurate lead screws, closer alignment, numerical control (NC) and computer numerical control (CNC) all result in faster work with better finishes and greater accuracy than ever before attained.

Column and Knee Machines

Type of milling machine Milling Machine

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Bed Type Milling Machines

Special Purpose Machines

Axes – StandardsMilling Machine

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Column and knee milling machines are made in both vertical and horizontal types.

Regardless of whether the machine is of the vertical or horizontal type, several components on all column and knee milling machines are similar, except for size and minor variations because of manufacturer’s preference. These similarities are described in terms of general shape, geometric relationship to the rest of the machine, function, and the material from which the components are made

Column and knee machinesMilling Machine

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Group 10Horizontal Milling machine Vertical Milling machine

Column: The column, which is usually combined with the base as a single casting, is cast gray iron or ductile iron.


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Spindle: On a horizontal milling machine, the spindle is one of the most critical parts. It is usually machined from an alloy steel forging and is heat treated to resist wear, vibration, thrust, and bending loads.

Knee: The knee is a casting that is moved up or down the slide on the front of the column by the elevating screw.

Saddle: The saddle for a plain milling machine is a casting with two slides machined at an exact 90 degree angle to each other.


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Table: Milling machine tables vary greatly in size, but generally they have the same physical characteristics.



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Bed type of milling machinesMilling Machine

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High production calls for heavy cuts, and the rigidity of a knee and column type of milling machine may not be sufficient to take the high forces. A bed-type milling machine is often ideal for this kind of work. In this machine the table is supported directly on a heavy bed, while the column is placed behind the bed

Bed type of milling machinesMilling Machine

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Planer-type milling machines: The general arrangement of these types of machines is similar to that for planers, except that in place of individual tool bits, milling heads are installed. The table of the machine carries the work past the rotating cutter heads, which are individually powered and can be run at different speeds if necessary

Special purpose machines Milling Machine

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Profile milling machines: Two dimensional profiling can be done by using a template, or with a numerically controlled vertical milling machine. Some profilers have several spindles, and a number of duplicate parts can be produced in each cycle.

Machining Centers

Computer controlled machining systemsMilling Machine

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Flexible Machining Systems

Basic components of CNC system

A typical CNC system consists of the following six elements:

Basic components of CNC systemMilling Machine

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Part program Program input device

Drive system

Machine tool

Feedback system

Machine control unit

NC system elements:Basic components of CNC system

Milling Machine

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Operational features of CNC machinesBasic components of CNC system

Milling Machine

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Basic components of CNC systemMilling Machine

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Part program Program input device

Drive system

Machine tool

Feedback system

Machine control unit

Part program Milling Machine

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A part program is a series of coded instructions required to produce a part. It controls the movement of the machine tool and the on/off control of auxiliary functions such as spindle rotation and coolant. The coded instructions are composed of letters, numbers and symbols and are arranged in a format of functional blocks as in the following example:N10 G01 X5.0 Y2.5 F15.0| | | | Feed rate (15 in/min )| | | Y-coordinate (2.5") | | X-coordinate (5.0") | Linear interpolation mode Sequence number

Program input devideMilling Machine

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The program input device is the mechanism for part programs to be entered into the CNC control. The most commonly used program input devices are keyboards, punched tape reader, diskette drivers, through RS 232 serial ports and networks.

Program Machine control unitMilling Machine

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The machine control unit (MCU) is the heart of a CNC system. It is used to perform the following functions:

Read coded instructions Implement interpolations (linear, circular, and helical) to

generate axis motion commands. Feed axis motion commands to the amplifier circuits for

driving the axis mechanisms. Receive the feed back signals of position and speed for

each drive axis. Implement auxiliary control functions such as coolant or

spindle on/off, and tool change

Machine control unitMilling Machine

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The machine control unit (MCU) is the heart of a CNC system. It is used to perform the following functions:

Read coded instructions Implement interpolations (linear, circular, and helical) to

generate axis motion commands. Feed axis motion commands to the amplifier circuits for

driving the axis mechanisms. Receive the feed back signals of position and speed for

each drive axis. Implement auxiliary control functions such as coolant or

spindle on/off, and tool change Types of CNC control systems:

Open - loop control Close - loop control

Drive systemMilling Machine

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A drive system consists of amplifier circuits stepping motors or servo motors and ball lead-screws. The MCU feeds control signals (position and speed) of each axis to the amplifier circuits. The control signals are augmented to actuate stepping motors which in turn rotate the ball lead-screws to position the machine table:

Recirculating ball screws

Step motor


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Step motor:A stepping motor provides open-loop, digital control of the position

of a workpiece in a numerical control machine. The drive unit receives a direction input (cw or ccw) and pulse inputs. For each pulse it receives, the drive unit manipulates the motor voltage and current, causing the motor shaft to rotate bya fixed angle (one step). The lead screw converts the rotary motion of the motor shaft into linear motion of the workpiece.


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Recirculating ball screws:Transform rotational motion of the motor into translational motion

of the nut attached to the machine table.Accuracy of CNC machines depends on their rigid construction,

care in manufacturing, and the use of ball screws to almost eliminate slop in the screws used to move portions of the machine.


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Recirculating ball screws:Transform rotational motion of the motor into translational motion

of the nut attached to the machine table. Ball screw Ball nut (anti-backlash) Ways Linear bearings

Machine toolMilling Machine

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CNC controls are used to control various type of machine tools. Regradless of which type of machine tool is controlled, it is always has a slide table and a spindle to control of position and speed. The machine table is controlled in the X and Y axes, whiles the spindle runs along the Z axis.

Feedback systemMilling Machine

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The feedback system is also referred to as the measuring system. It uses position and speed transducers to continuously monitor the position at which the cutting tool is located at any particular time. The MCU uses the difference between reference signals and feedback signals to generate the control signals for correcting position and speed errors.

Encoders: A device used to convert linear or rotational position information into an electrical output signal.


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Resolvers:A resolver is a rotary transformer that produces an output signal

that is a function of the rotor position.

Drive motors: DC servo motors AC servo motors Stepper motors Hydraulic motors


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Velocity feedback: Tachometers:

Electrical output is proportional to rate of angular rotation. Encoders, Resolvers, Potentiometers:

Number of pulses per time is proportional to rate change of position.

CNC programingMilling Machine

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Important things to know: Coordinate System Units incremental or absolute positioning Coordinates: X,Y,Z, Feed rate and spindle speed Coolant Control: On/Off, Flood, Mist Tool Control: Tool and tool parameters


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Programming consists of a series of instructions in form of letter codes:

- G codes- Initial machining setup and establishing operating conditions

- N codes- specify program line number to executed by the MCU- Axis Codes: X,Y,Z - Used to specify motion of the slide along X, Y, Z direction- Feed and Speed Codes: F and S- Specify feed and spindle

speed- Tool codes: T – specify tool number - Miscellaneous codes – M codes For coolant control and other

activities


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Programming Key Letters: O - Program number (Used for program identification) N - Sequence number (Used for line identification) G - Preparatory function X - X axis designation Y - Y axis designation Z - Z axis designation R - Radius designation F - Feed rate designation S - Spindle speed designation H - Tool length offset designation D - Tool radius offset designation T - Tool Designation M - Miscellaneous function


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Preparatory Function (G Address): A preparatory function dertermine how the tool is to move to the

programed target. The most common G addresses are listed below: Code FunctionG00 Rapid TransverseG01 Linear InterpolationG02 Circular Interpolation, CW (clockwise)G03 Circular Interpolation, CCW (counter clockwise) G17 XY Plane,G18 XZ Plane,G19 YZ PlaneG20/G70 Inch unitsG21/G71 Metric UnitsG40 Cutter compensation cancelG41 Cutter compensation left


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G42 Cutter compensation right G43 Tool length compensation (plus) G43 Tool length compensation (plus) G44 Tool length compensation (minus) G49 Tool length compensation cancel G80 Cancel canned cycles G81 Drilling cycle G82 Counter boring cycle G83 Deep hole drilling cycle G90 Absolute positioning G91 Incremental positioning


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Miscellaneous Function (M address):The miscellaneous function is programed to control the

machine operation other than for co ordinate movement. The most common M functions are as follows:

Code Function M00 Program stop M01 Optional program stop M02 Program end M03 Spindle on clockwise M04 Spindle on counterclockwise M05 Spindle stop M06 Tool change


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M08 Coolant on M09 Coolant off M10 Clamps on M11 Clamps off M30 Program stop, reset to start

Machining Centers Horizontal Machines Vertical machine

Computer controlled machining systemsMilling Machine

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Flexible Machining Systems Material Handling Control systems: have three function level:

master control, direct numberical control, element control

Milling cutters

Milling Machine

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Other attachments and accessories


Milling cutters. Types of Teeth:

The teeth of milling cutters may be made for right-hand or left-hand rotation, and with either right-hand or left-hand helix. Determine the hand of the cutter by looking at the face of the cutter when mounted on the spindle. A right-hand cutter must rotate counterclockwise; a left-hand cutter must rotate clockwise.

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Milling cutters. Saw Teeth:

Saw teeth are either straight or helical. The cutting edge is usually given about 5 degrees primary clearance. Sometimes the teeth are provided with off-set nicks which break up chips and make coarser feeds possible.


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Helical Milling Cutters:The helical milling cutter is similar, to the plain milling cutter, but the teeth have a helix angle of 45° to 60°. This type of helical cutter is particularly useful for milling elongated slots and for light cuts on soft metal


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Types of milling cutter.

Metal Slitting Saw Milling Cutter: The metal slitting saw milling cutter is essentially a very thin plain milling cutter. It is ground slightly thinner toward the center. It is used for cutoff operations and for milling deep, narrow slots, and are made in widths from 1/32 to 3/16 inch.


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Side Milling Cutters: Side milling cutters are essentially plain milling cutters with the addition of teeth on one or both sides. When teeth are added to one side only, the cutter is called a half-side milling cutter and is identified as being either a right-hand or left-hand cutter. Side milling cutters are generally used for slotting and straddle milling.


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End Milling Cutters: End milling cutters may have straight or spiral flutes. Spiral flute end milling cutters are classified as left-hand or right-hand cutters depending on the direction of rotation of the flutes. If they are small cutters, they may have either a straight or tapered shank.


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End Milling Cutters: The most common end milling cutter is the spiral flute cutter containing four flutes. Two-flute end milling cutters, sometimes referred to as two-lip end mill cutters, are used for milling slots and keyways where no drilled hole is provided for starting the cut. Straight flute end milling cutters are generally used for milling both soft or tough materials, while spiral flute cutters are used mostly for cutting steel.


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T-Slot Milling Cutter:The T-slot milling cutter is used to machine T-slot grooves in worktables, fixtures, and other holding devices. The cutter has a plain or side milling cutter mounted to the end of a narrow shank. The throat of the T-slot is first milled with a side or end milling cutter and the headspace is then milled with the T-slot milling cutter.


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Woodruff Keyslot Milling Cutters:

The Woodruff keyslot milling cutter is made in straight, tapered-shank, and arbor-mounted types. The most common cutters of this type, under 1 1/2 inches in diameter, are provided with a shank. They have teeth on the periphery and slightly concave sides to provide clearance. These cutters are used for milling semicylindrical keyways in shafts.


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Angle Milling Cutters: The angle milling cutter has peripheral teeth which are neither parallel nor perpendicular to the cutter axis. Common operations performed with angle cutters are cutting V-notches and serration's. Angle cutters may be single-angle milling cutters or double-angle milling cutters. The single-angle cutter contains side-cutting teeth on the flat side of the cutter. The angle of the cutter edge is usually 30°, 45°, or 60°, both right and left. Double-angle cutters have included angles of 45, 60, and 90 degrees.


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Gear Hob: The gear hob is a formed tooth milling cutter with helical teeth arranged like the thread on a screw. Hobs are generally used for such work as finishing spur gears, spiral gears, and worm gears. They may also be used to cut ratchets and spline shafts.


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Concave and Convex Milling Cutters: Concave and convex milling cutters are formed tooth cutters shaped to produce concave and convex contours of 1/2 circle or less.


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Corner Rounding Milling Cutter:The corner-rounding milling cutter is a formed tooth cutter used for milling rounded corners on workpieces up to and including one-quarter of a circle. The concave and convex cutters generally used for such work as finishing spur gears, spiral gears


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Special Shaped-Formed Milling Cutter: Formed milling cutters have the advantage of being adaptable to any specific shape for special operations. The cutter can be sharpened many times without destroying its shape.


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Milling cutters

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Other attachments and accessories


Arbors: Milling machine arbors are made in various lengths and in standard diameters of 7/8,1,1 1/4, and 1 1/2 inch. The shank is made to fit the taper hole in the spindle while the other end is threaded.The milling machine spindle may be self-holding or self-releasing. Arbors are supplied with one of three tapers to fit the milling machine spindle: the Standard Milling Machine taper, the Brown and Sharpe taper, and the Brown and Sharpe taper with tang.

Other attachment and accessories.Milling Machine

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Standard Milling Machine Arbor:The standard milling machine arbor has a tapered, cylindrical shaft with a standard milling taper on the driving end and a threaded portion on the opposite end to receive the arbor nut.The standard milling machine arbor is usually splined and keys are used to lock each cutter to the arbor shaft. These arbors are supplied in three styles, various lengths and, standard diameters.


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Screw Arbor: Screw arbors are used to hold small cutters that have threaded holes. These arbors have a taper next to the threaded portion to provide alignment and support for tools that require a nut to hold them against a taper surface. A right-hand threaded arbor must be used for right-hand cutters while a left-hand threaded arbor is used to mount left-hand cutters.

Other attachment and accessories.

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Spindle Adapters : A spindle adapter is a form of a collet having a standardized spindle end. They are available in a wide variety of sizes to accept cutters that cannot be mounted on arbors. They are made with either the Morse taper shank or the Brown and Sharpe taper with tang having a standard spindle end.

Other attachment and accessories

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Chuck Adapter : A chuck adapter is used to attach chucks to milling machines having a standard spindle end. The collet holder is sometimes referred to as a collet chuck. Various forms of chucks can be fitted to milling machines spindles for holding drills, reamers, and small cutters for special operations.


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Quick-Change Tooling : The quick-change adapter mounted on the spindle nose is used to speed up tool changing. Tool changing with this system allows you to set up a number of milling operations such as drilling, end milling, and boring without changing the setup of the part being machined. The tool holders are mounted and removed from a master holder mounted to the machine spindle by means of a clamping ring


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Vises: Have two a plain or swivel-type vise is furnished with each milling machine.

The plain vise, similar to the machine table vise, is used for milling straight workpieces and is bolted to the milling machine table either at right angles or parallel to the machine arbor.


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The swivel vise can be rotated and contains a scale a plain or swivel-type vise is furnished with each milling machine.graduated in degrees at its base to facilitate milling workpieces at any angle on a horizontal plane.


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Other attachment and accessories. The universal vise, which may be obtained as extra

equipment, is designed so that it can be set at both horizontal and vertical angles.


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Adjustable Angle Plate: The adjustable angle plate is a workpiece holding device, similar to the universal vise in operation. Workpieces are mounted to the angle plate with T-bolts and clamps in the same manner used to fasten workpieces to the worktable of the milling machine. The angle plate can be adjusted to any angle so that bevels and tapers can be cut without using a special milling cutter or an adjustable cutter head.


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Indexing Fixture: The index fixture consists of an index head, also called a dividing head, and footstock which is similar to the tailstock of a lathe.


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High-Speed Milling Attachment: This attachment is essential when using cutters and twist drills which must be driven at a high rate of speed in order to obtain an efficient surface speed. The attachment is clamped to the column of the machine and is driven by a set of gears from the milling machine spindle.


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Vertical Spindle Attachment: This attachment converts the horizontal spindle of a horizontal milling machine to a vertical spindle. It is clamped to the column and driven from the horizontal spindle. It incorporates provisions for setting the head at any angle, from the vertical to the horizontal, in a plane at right angles to the machine spindle.


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Universal Milling Attachment: This device is similar to the vertical spindle attachment but is more versatile. The cutter head can be swiveled to any angle in any plane, whereas the vertical spindle attachment only rotates in one place from horizontal to vertical.


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Rotary Table Or Circular Milling Attachment: This attachment consists of a circular worktable containing T-slots for mounting workpieces. The circular table revolves on a base attached to the milling machine worktable.


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Milling Machine

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