There is a wide variety of processes that can be classified under the above definition of forging. This manual will address five: open die, impression die, ring rolling, warm forging and cold forging. Cold forging is performed at or near room temperature, and work hardening occurs. The other processes are performed at elevated temperatures, where work hardening is diminished or the workpiece is not work hardened at all.
Open Die Forging is a hot forming process, which uses standard flat, "V" or swage dies. The hot workpiece temperature improves plastic flow characteristics and reduces the force required to work the metal. The desired shape is systematically formed by a relatively large number of strokes.
Open die forging is normally used to produce large parts, which are often well beyond the range of impression die processes. It is sometimes used to produce substantially the same shapes as impression die. In these applications it offers no chargeable tooling cost and very short lead time. However, per-piece processing costs are higher, dimensional precision is not as good, and more finish machining operations are required compared with impression die forging. The process is shown schematically in Figure 1-3.
Impression Die Forging utilizes a pair of matched dies with contoured impressions in each die. When the dies close, the impressions form a cavity in the shape of the forging. Often two or more progressive impressions are used, sometimes in conjunction with one or more preforming operations, to form the desired shape. The proper forging temperature improves plastic flow characteristics and reduces the forces on the forging tools. The process is shown schematically in Figure 1-4.
Ring Rolling forms axisymmetric shapes in a hot forming process. The process begins with a "donut" shaped preform, which is made by upsetting and piercing operations. The preform is placed over the idler or mandrel roll in a ring rolling mill. The idler roll is moved toward a drive roll, which rotates to reduce the wall and increase the diameter, while forming the desired shape. The process is shown schematically in Figure 1-5. Cross sections of typical ring rolled shapes are shown in Figure 1-6.
Figure 1-3 The open die forging process
Process Operations
Upsetting
Figure 1-4 The impression die forging process
Cold Forging employs dies that are sometimes similar to impression dies. The temperature of the workpiece is low enough that scale does not form, but the workpiece work hardens. The lower temperature also promotes greater dimensional accuracy. However, the plastic flow characteristics are not as good at the reduced temperatures, and higher applied forces are required. The three basic cold forging processes are shown in Figure 1-7.
Warm forging is a modification of the cold forging process where the workpiece is heated to a temperature significantly below the typical hot forging temperature.
Forging offers the designer several basic performance advantages to a degree that sets it above alternate processes.
Return to Table of Contents
array (
'#markup' => '
There is a wide variety of processes that can be classified under the above definition of forging. This manual will address five: open die, impression die, ring rolling, warm forging and cold forging. Cold forging is performed at or near room temperature, and work hardening occurs. The other processes are performed at elevated temperatures, where work hardening is diminished or the workpiece is not work hardened at all.
Open Die Forging is a hot forming process, which uses standard flat, "V" or swage dies. The hot workpiece temperature improves plastic flow characteristics and reduces the force required to work the metal. The desired shape is systematically formed by a relatively large number of strokes.
Open die forging is normally used to produce large parts, which are often well beyond the range of impression die processes. It is sometimes used to produce substantially the same shapes as impression die. In these applications it offers no chargeable tooling cost and very short lead time. However, per-piece processing costs are higher, dimensional precision is not as good, and more finish machining operations are required compared with impression die forging. The process is shown schematically in Figure 1-3.
Impression Die Forging utilizes a pair of matched dies with contoured impressions in each die. When the dies close, the impressions form a cavity in the shape of the forging. Often two or more progressive impressions are used, sometimes in conjunction with one or more preforming operations, to form the desired shape. The proper forging temperature improves plastic flow characteristics and reduces the forces on the forging tools. The process is shown schematically in Figure 1-4.
Ring Rolling forms axisymmetric shapes in a hot forming process. The process begins with a "donut" shaped preform, which is made by upsetting and piercing operations. The preform is placed over the idler or mandrel roll in a ring rolling mill. The idler roll is moved toward a drive roll, which rotates to reduce the wall and increase the diameter, while forming the desired shape. The process is shown schematically in Figure 1-5. Cross sections of typical ring rolled shapes are shown in Figure 1-6.
Figure 1-3 The open die forging process
Process Operations
Upsetting
Figure 1-4 The impression die forging process
Cold Forging employs dies that are sometimes similar to impression dies. The temperature of the workpiece is low enough that scale does not form, but the workpiece work hardens. The lower temperature also promotes greater dimensional accuracy. However, the plastic flow characteristics are not as good at the reduced temperatures, and higher applied forces are required. The three basic cold forging processes are shown in Figure 1-7.
Warm forging is a modification of the cold forging process where the workpiece is heated to a temperature significantly below the typical hot forging temperature.
Forging offers the designer several basic performance advantages to a degree that sets it above alternate processes.
Return to Table of Contents
',
'#printed' => true,
'#type' => 'markup',
'#pre_render' =>
array (
0 => 'drupal_pre_render_markup',
1 => 'ctools_dependent_pre_render',
),
'#children' => '
There is a wide variety of processes that can be classified under the above definition of forging. This manual will address five: open die, impression die, ring rolling, warm forging and cold forging. Cold forging is performed at or near room temperature, and work hardening occurs. The other processes are performed at elevated temperatures, where work hardening is diminished or the workpiece is not work hardened at all.
Open Die Forging is a hot forming process, which uses standard flat, "V" or swage dies. The hot workpiece temperature improves plastic flow characteristics and reduces the force required to work the metal. The desired shape is systematically formed by a relatively large number of strokes.
Open die forging is normally used to produce large parts, which are often well beyond the range of impression die processes. It is sometimes used to produce substantially the same shapes as impression die. In these applications it offers no chargeable tooling cost and very short lead time. However, per-piece processing costs are higher, dimensional precision is not as good, and more finish machining operations are required compared with impression die forging. The process is shown schematically in Figure 1-3.
Impression Die Forging utilizes a pair of matched dies with contoured impressions in each die. When the dies close, the impressions form a cavity in the shape of the forging. Often two or more progressive impressions are used, sometimes in conjunction with one or more preforming operations, to form the desired shape. The proper forging temperature improves plastic flow characteristics and reduces the forces on the forging tools. The process is shown schematically in Figure 1-4.
Ring Rolling forms axisymmetric shapes in a hot forming process. The process begins with a "donut" shaped preform, which is made by upsetting and piercing operations. The preform is placed over the idler or mandrel roll in a ring rolling mill. The idler roll is moved toward a drive roll, which rotates to reduce the wall and increase the diameter, while forming the desired shape. The process is shown schematically in Figure 1-5. Cross sections of typical ring rolled shapes are shown in Figure 1-6.
Figure 1-3 The open die forging process
Process Operations
Upsetting
Figure 1-4 The impression die forging process
Cold Forging employs dies that are sometimes similar to impression dies. The temperature of the workpiece is low enough that scale does not form, but the workpiece work hardens. The lower temperature also promotes greater dimensional accuracy. However, the plastic flow characteristics are not as good at the reduced temperatures, and higher applied forces are required. The three basic cold forging processes are shown in Figure 1-7.
Warm forging is a modification of the cold forging process where the workpiece is heated to a temperature significantly below the typical hot forging temperature.
Forging offers the designer several basic performance advantages to a degree that sets it above alternate processes.
Return to Table of Contents
',
)