seminar-machining centers and machine tool structures

7/30/2019 Seminar-Machining Centers and Machine Tool Structures

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Machining Centers andMachine Tool Structures

Presented byNITESH P. WANKHADE (12MCD1003)

M.TECH (CAD-CAM)


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Introduction

Computers improved the capabilities of machine tools

Have the capability of rapidly producing extremely

complex part geometries


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Machining Centers

Brief review:1. Possibilities exist in net-shape or near-net shape

production

2. Some form of machining is required and is moreeconomical to finish machine parts to their final shapes


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Machining Centers

The Concept of Machining Centers Machining parts can be highly automated to increaseproductivity

Transfer lines are used in high-volume or mass production, consist of several specific machine toolsarranged in a logical sequenceWorkpiece is moved from station to station, with a

specific machining operation performed at each station A machining center is an advanced computer-controlled machine tool that perform machiningoperations without removing


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Machining Centers


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Machining Centers

Components of a Machining Center The workpiece in a machining center is placed on apallet , or module

Can be moved and swiveled in various directionsNew pallet is brought in by an automatic palletchanger

A machining center is equipped with a programmable

automatic tool changer (ATC)


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Machining Centers

Components of a Machining Center The tool-exchange arm swings around to pick up aparticular tool and places it in the spindle

Tool-checking and/or part-checking station wouldfeeds information to the machine control systemTouch probes select the tool settings and inspect partsbeing machined


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Machining Centers:Types of Machining Centers

Vertical-spindle Machining Centers Performing various machiningoperations on parts with deepcavities, as in mold and die making

Horizontal-spindle Machining CentersSuitable for large and

tall work pieces thatrequire machining on anumber of their surfaces


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Machining Centers:Characteristics and Capabilities of Machining Centers

Major characteristics of machining centres:1. Handles a wide variety of part sizes and shapes

efficiently

2. Versatile and quick changeover 3. Time required is reduced4. Detection of tool breakage and wear 5. Inspection of machined work6. Compact and highly automated


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Machining Centers:Selection of Machining Centers

Selection of type and size of machining centersdepends on:

1. Type of products, their size, and their shape complexity

2. Type of machining operations to be performed and thetype and number of cutting tools required3. Dimensional accuracy required4. Production rate required


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Machining Centers:Selection of Machining Centers

EXAMPLE 25.1 Machining Outer Bearing Races on a Turning Center

Machining of outer bearing races


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Machining Centers:Reconfigurable Machines and Systems

There is a need for the flexibility of manufacturingwhich involve concept of reconfigurable machines,consisting of various modules3 axis machining center can perform differentmachining operations while accommodating variousworkpiece sizes and part geometries


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Machining Centers:Reconfigurable Machines and Systems

A five-axis machine can be reconfigured by assemblingdifferent modules


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Machine-tool Structures:Materials

A list of materials suitable for machine-tool structures:1. Gray cast iron2. Welded steel

3. Ceramic4. Composites5. Granite epoxy composites6. Polymer concrete


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Machine-tool Structures:Machine-tool Design Considerations

Important considerations in machine tools:1. Design, materials, and construction 2. Spindle materials and construction

3. Thermal distortion of machine components 4. Error compensation and the control of moving

components along slideways


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Stiffness It is a function of the:

1. Elastic modulus of the materials used

2. Geometry of the structural componentsEnhanced by using diagonally arranged interior ribs

Thermal Distortion2 sources of heat in machine tools:

1. Internal sources2. External sources


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Assembly Techniques for Machine-tool Components Traditionally components have been assembled usingthreaded fasteners and welding

Advanced assembly techniques include integral castingand resin bonding

Guideways

Plain cast-iron ways in machines require much care toachieve the required precision and service life


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Linear Motor Drives A linear motor is a typical rotary electric motor that hasbeen rolled out (opened) flat

Sliding surfaces in drives are separated by an air gapand have very low frictionSome advantages:

1. Simplicity and minimal maintenance

2. Smooth operation, better positioning accuracy, andrepeatability

3. Wide range of linear speeds4. Moving components encounter no wear


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High-speed Machining

Spindle designs for high speeds require high stiffnessand accuracy Due to inertia effects during the acceleration anddecelaration of machine-tool components, there is ause of lightweight materials considerationHigh-speed machining should take cutting time as acosiderationHigh-speed machining is economical for certainspecific applications

As cutting speed increases, more heat is generated,while the tool and workpiece should remain close toambient temperature


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Thank You..

seminar-machining centers and machine tool structures

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