DESIGNATION AND RELATIVE POSITIONS OF VIEWS
Extrusion Blow Molding Machine Parts and Functions
Extrusion Blow Molding Machine Parts and Functions
• Extruder Motor—Drives the screw in the barrel to rotate and push the
melted material into the die head.
• Gearbox—Reduces the speed of the extruder motor into a required speed enough to push the material into the die head.
• Hopper—A feed reservoir into which the material is loaded.
• Extruder—A part of the machine that accepts solid resin material, conveys it in a surrounding barrel by means of a rotating screw, melts the
material by means of heaters, and pumps it under pressure into the die
head.
• Cooling Fans—Cools down the barrel during machine shut down to prevent the material from degradation.
• Heating Bands—Device attached on the barrel and the die head used to melt the solid material at a required set temperature.
• Die Head—Used to form the melted resin into a parison and also used for adjusting the characteristics of molten resin to create a stable parison.
• Die & Pin—Used to align the flow of parison to get a good and centered parison.
• Hot Cutter—Cuts the parison after the mold is closed for the blowing process.
• Blow Pin—Used to blow compressed air into the parison to inflate it after the mold has been closed and form the desired design of the mold.
• Mold—A hollow form or a cavity into which a molten plastic material, called parison, is introduced to give the shape of the required component.
• Deflasher—Used to cut the excess material on the bottle which is called a flash material (top and bottom).
• Post Cooling—A part of the machine that is used to cool down the inside of the bottle, to lessen the cooling time required inside the mold.
• Article Discharge—A part of the machine used to take the bottle out.
Higher Institute for Plastics Fabrication
WORKBOOK
for
Extrusion Blow Molding
Practical Course
Prepared by
Extrusion Blow Molding Department
1st Edition 2009
What Is Computer-Aided Process Planning (CAPP)?
In this section we introduce the topic of CAPP, and review important components of this technology. Chang and Wysk (1985) define process planning as “machining processes and parameters that are to be used to convert (machine) a workpiece from its initial form to a final form predetermined from an engineering drawing.” Implicit in their definition is the selection of machining resources (machine and cutting tools), the specification of setups and fixturing, and the generation of operation
sequences and numerical control (NC) code. Traditionally, the task of process planning is performed by a human process planner with acquired expertise in machining practices who determines from a part’s engineering drawings what the machining requirements are.
Manual process planning has many drawbacks. In particular, it is a slow, repetitive task that is prone to error. With industry’s emphasis on automation for improved productivity and quality, computerized CAD and computer-aided manufacturing (CAM) systems which generate the data for driving computer numerical control (CNC) machine tools, are the state-of-the-art. Manual process planning in this context is a bottleneck to the information flow between design and manufacturing.
CAPP is the use of computerized software and hardware systems for automating the process planning task. The objective is to increase productivity and quality by improving the speed and accuracy of process planning through automation of as many manual tasks as possible. CAPP will increase automation and promote integration among the following tasks:
1. Recognition of machining features and the construction of their associated machining volumes from a geometric CAD model of the part and workpiece
2. Mapping machining volumes to machining operations
3. Assigning operations to cutting tools
4. Determining setups and fixturing
5. Selecting suitable machine tools
6. Generating cost-effective machining sequences
7. Determining the machining parameters for each operation
8. Generating cutter location data and finally NC machine code
Traditionally, CAPP has been approached in two ways. These two approaches are variant process planning and generative process planning. In the following section we discuss these and other issues in a review of work in this field.
THE
MECHANICAL
SYSTEMS
DESIGN
HANDBOOK
Modeling, Measurement,
and Control
OSITA D. I. NWOKAH
YILDIRIM HURMUZLU
Southern Methodist University
Dallas, Texas
CRC PRESS
Boca Raton London New York Washington, D.C.
Polymer molding
Thermoplastics are molded as viscous liquids. Injection molding and extrusion dominate, but all molding processes impose flow that can orientate the molecules; if the molding is cooled fast enough the alignment is frozen in (Figure 19.5).
If not, polymers mostly prefer to form an amorphous structure. In some polymers crystallinity may develop on slow cooling. All polymers shrink as the mold cools from the molding temperature to room temperature because of thermal contraction and the loss of free volume caused by crystallization. Allowance must be made for this when the mold is designed.
Materials
Engineering, Science,
Processing and Design
Michael Ashby, Hugh Shercliff and David Cebon
University of Cambridge,
UK
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