Quick plastic forming of aluminum alloy sheet metal

A method of forming an article of manufacture from a metal alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first rate from ambient, and the second stage comprising increasing the pressure at a second rate, and wherein the second stage occurs after the first stage and the second rate is greater than the first rate and further comprising applying a final stretching pressure during the second stage, and wherein the final stretching pressure ranges from about 250 psi to about 500 psi above ambient pressure.

A method of forming an article of manufacture from a metal alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying a working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure from ambient at a first rate to a first stage ending pressure, and the second stage comprising increasing the pressure at a second rate from the first stage ending pressure, and wherein the second rate is greater than the first rate, and wherein the second rate is non-linear.

A method of forming an article of manufacture from a metal alloy sheet stock comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• applying pressure, in a range of about 250 psi to about 500 psi above ambient pressure, on the heated sheet in a series of stages to bring the sheet into conformance with the forming surface, the series of stages comprising a first stage, a second stage, and a final forming stage;
• and wherein of the pressure applied in the first stage is increased at a first average rate, and wherein the pressure applied in the second stage is at a second average rate that is greater than a first average rate, and wherein the pressure applied in the final forming stage is substantially constant.

A method of forming an article of manufacture from a metal alloy sheet comprising:

• providing a metal alloying sheet stock having a microstructure grain size ranging from about 5-30 micrometers, and providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• applying pressure, in a range of about 250 psi to about 500 psi above ambient pressure, on the heated sheet in a series of stages to bring the sheet into conformance with the forming surface, the series of stages comprising a first stage, a second stage, and a final forming stage;
• and wherein the pressure applied in the first stage is increased at a first rate, and wherein the pressure applied in the second stage is at a second rate that is greater than a first rate, and wherein the pressure applied in the final forming stage is substantially constant.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first average rate from ambient, and the second stage comprising increasing the pressure at a second average rate, and wherein the second stage occurs after the first stage, and the second average rate is greater than the first average rate.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet to a temperature ranging from about 400° C. to about 510° C. and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first average rate from ambient, and the second stage comprising increasing the pressure at a second average rate, and wherein the second stage occurs after the first stage and the second average rate is greater than the first average rate.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first rate from ambient, and the second stage comprising increasing the pressure at a second rate, and wherein the second stage occurs after the first stage and the second rate is greater than the first rate, and wherein the aluminum alloy has a microstructure grain size of 5-30 micrometers.

A method of forming an article of manufacture from a metal alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure from ambient at a first rate to a first stage ending pressure, and the second stage comprising increasing the pressure at a second rate from the first stage ending pressure, and wherein the second rate is greater than the first rate, and wherein the second rate is non-linear, the stretching including a final stretching pressure in a range of about 250 psi to about 500 psi above ambient pressure.

A method of forming an article of manufacture from a metal alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure from ambient at a first rate to a first stage ending pressure, and the second stage comprising increasing the pressure at a second rate from the first stage ending pressure, and wherein the second rate is greater than the first rate, and wherein the second rate is non-linear, said stretching being accomplished such that at least a portion of the sheet experiences a strain rate greater than 10−3 sec−1.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first average rate from ambient, and the second stage comprising increasing the pressure at a second average rate, and wherein the second stage occurs after the first stage, and the second average rate is greater than the first average rate, the stretching being accomplished such that at least a portion of the sheet experiences a strain rate greater than 10−3 sec−1.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first average rate from ambient, and the second stage comprising increasing the pressure at a second average rate, and wherein the second stage occurs after the first stage, and the second average rate is greater than the first average rate, the stretching including a final stretching pressure in a range of about 250 psi to about 500 psi above ambient pressure.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet to a temperature ranging from about 400° C. to about 510° C. and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first average rate from ambient, and the second stage comprising increasing the pressure at a second average rate, and wherein the second stage occurs after the first stage and the second average rate is greater than the first average rate, the stretching being accomplished such that at least a portion of the sheet experiences a strain rate greater than 10−3 sec−1.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first rate from ambient, and the second stage comprising increasing the pressure at a second rate, and wherein the second stage occurs after the first stage and the second rate is greater than the first rate, and wherein the aluminum alloy has a microstructure grain size of 5-30 micrometers, the stretching including a final stretching pressure in a range of about 250 psi to about 500 psi above ambient pressure.

A method of forming an article of manufacture from an aluminum alloy sheet comprising:

• providing a sheet forming tool having engagement surfaces for engaging the sheet near peripheral edges thereof so that the sheet can be held in sealing engagement with the sheet forming tool, the sheet forming tool having a sheet forming surface for forming the sheet;
• heating the sheet and holding the sheet in sealing engagement with the engagement surfaces of the sheet forming tool, the sheet having a first surface facing the sheet forming surface and an opposite surface;
• stretching the heated sheet into conformance with the forming surface by applying working gas pressure, in a range of about 250 psi to about 500 psi above ambient pressure, to the opposite surface of the sheet, the stretching being accomplished by applying the pressure in a series of stages comprising a first stage, and a second stage;
• and wherein the first stage comprises increasing the pressure at a first rate from ambient, and the second stage comprising increasing the pressure at a second rate, and wherein the second stage occurs after the first stage and the second rate is greater than the first rate, and wherein the aluminum alloy has a microstructure grain size of 5-30 micrometers, the stretching being accomplished such that at least a portion of the sheet experiences a strain rate greater than 10−3 sec−1.