High-volume low pressure air spray gun

A method of spraying liquid coating material with an apparatus having a body and a spray head carried by the body, comprising the steps of delivering liquid coating material to a fluid orifice in the spray head;

• supplying air at a low volume and high pressure to an inlet to a passage in the body;
• converting the low volume high pressure air at the inlet to the body passage to high volume low pressure air at an outlet from the passage;
• connecting the outlet from the passage to inlets to an atomizing air orifice and side port orifices in the spray head for flow of high volume low pressure air through the atomizing air orifice to atomize the coating material into a spray and through the side port orifices for impingement against and to shape the spray;
• adjusting the flow rate of air through the inlet to the side port orifices to change the shape of the spray;
• and, in response to and concurrently with performance of said adjusting step, changing the flow rate of high volume low pressure air at the body passage outlet by an amount correlated to the change in the flow rate of air through the inlet to the side port orifices, so that a change in the flow rate of air through the inlet to the side port orifices does not significantly change the pressure of air at the atomizing air orifice.

Apparatus for spray coating, comprising a spray head having a fluid orifice, an atomizing air orifice and an inlet thereto, and side port air orifices and an inlet thereto;

• means for providing liquid coating material to said fluid orifice;
• air supply passage means for supplying air to said spray head inlets for delivery to and flow through said atomizing air orifice to atomize coating liquid into a spray and for delivery to and flow through said side port orifices for impingement against and to shape the spray;
• means for adjusting the volume flow rate of air delivered to said side port orifices to vary the shape of the spray;
• and means, responsive to operation of said adjusting means, for concurrently and correspondingly adjustably controlling the volume flow rate of air through said air supply passage means.

Apparatus for spray coating, comprising a spray head having a fluid orifice, a first passageway extending between an inlet to said first passageway and an atomizing air orifice, and a second passageway extending between an inlet to said second passageway and side port air orifices;

• means for delivering liquid coating material to said fluid orifice;
• means for supplying air through a common passageway to said inlets for delivery through said first passageway to said atomizing air orifice to atomize the coating material into a spray and through said second passageway to said side port orifices for impingement against and to shape the spray;
• means for adjusting the air flow area through said second passageway inlet to control the volume flow rate of air delivered to said side port orifices to vary the shape of the spray;
• and means, responsive to operation of said adjusting means, for concurrently and correspondingly changing the air flow area through said common passageway so that the pressure of air at said atomizing air orifice does not change significantly in response to changes in the volume flow rate of air delivered to said side port orifices.

Apparatus for spray coating, comprising a body having an air passage therethrough;

• a spray head carried by said body, said spray head having a fluid orifice, an atomizing air orifice and an inlet thereto, and side port air orifices and an inlet thereto, said inlets being coupled with an outlet from said body passage;
• means for delivering liquid coating material to said spray head fluid orifice;
• means for supplying air at a low volume and high pressure to an inlet to said body passage;
• means for converting the low volume high pressure air at said body passage inlet to high volume low pressure air at said body passage outlet for delivery to said spray head inlets for flow through said atomizing air orifice to atomize coating liquid into a spray and through said side port orifices for impingement against and to shape the spray;
• means for adjusting the volume flow rate of air through said inlet to said side port orifices to change the shape of the spray;
• and means, responsive to operation of said adjusting means, for concurrently changing the volume flow rate of high volume low pressure air at said body passage outlet by an amount correlated to the change in the flow rate of air through said inlet to said side port orifices, so that a change in the flow rate of air through said inlet to said side port orifices does not significantly change the pressure of air at said atomizing air orifice.

A spray gun for atomizing liquid coating material, comprising a spray gun body having an air passage extending between an inlet to and an outlet from said passage;

• a spray head carried on said body, said spray head having a fluid orifice, an atomizing air orifice having an inlet thereto and side port air orifices having an inlet thereto, said inlets being in communication with said body passage outlet;
• a restriction in said body passage, said restriction having an air flow passage therethrough;
• a single valve member for simultaneously adjusting the resistance to a flow of air through said restriction and the resistance to a flow of air through said inlet to said side port orifices;
• means for delivering liquid coating material to said spray head fluid orifice for emission therefrom;
• means for supplying low volume high pressure air to said body passage inlet for flow through said restriction to said body passage outlet, said restriction converting the low volume high pressure air at said body passage inlet to high volume low pressure air at said body passage outlet for flow through said spray head inlets to said atomizing air orifice to atomize the coating material into a spray and to said side port orifices for impingement against and to shape the spray;
• and means for operating said valve member to simultaneously adjust the resistance to a flow of air through said restriction and the resistance to a flow of air through said inlet to said side port orifices, such that the resistances either simultaneously increase or decrease by amounts such that, upon a change in the resistance to a flow of air through said inlet to said side port orifices to change the shape of the spray, the volume flow rate of air through said inlet to said atomizing air orifice does not change by an amount that significantly changes the pressure of air at said atomizing air orifice.

A method of spraying liquid coating material, comprising the steps of providing liquid coating material to a fluid orifice in a spray head for emission therefrom;

• supplying air to an air supply passage for the spray head;
• delivering air from the air supply passage to an atomizing air orifice in the spray head to atomize the emitted coating material into a spray;
• selectively delivering air from the air supply passage to shaping air orifices in the spray head for impingement against and to shape the spray;
• adjusting the volume flow rate of air delivered to the shaping air orifices to adjust the shape of the spray;
• and, in response to and concurrently with performance of said adjusting step, correspondingly adjustably controlling the volume flow rate of air through the air supply passage to prevent the pressure of air at the spray head from exceeding a selected maximum pressure as a result of changes in the volume flow rate of air delivered to the shaping air orifices.

A method of spraying liquid coating material with a spray head having a fluid orifice, a first passageway extending to an atomizing air orifice and a second passageway extending to shaping air orifices, comprising the steps of delivering liquid coating material to the fluid orifice for emission therefrom;

• supplying air through a common passageway to the spray head;
• delivering air supplied to the spray head through the first passageway to the atomizing air orifice to atomize the emitted coating material into a spray;
• selectively delivering air supplied to the spray head through the second passageway to the shaping air orifices for impingement against and to shape the spray;
• adjusting the air flow area through the second passageway to control the volume flow rate of air delivered to the shaping air orifices to adjust the shape of the spray;
• and, in response to and concurrently with performance of said adjusting step, correspondingly varying the air flow area through the common passageway to change the volume flow rate of air supplied to the spray head to prevent the pressure of air at the spray head from exceeding a selected maximum pressure as a result of changes in the volume flow rate of air delivered to the shaping air orifices.

A method of spraying liquid coating material with an apparatus having a body and a spray head carried by the body, comprising the steps of delivering liquid coating material to a fluid orifice in the spray head for emission therefrom;

• supplying air at a low volume and high pressure to an inlet to a passage in the body;
• converting the low volume high pressure air at the body passage inlet to high volume low pressure air at an outlet from the body passage;
• connecting the air at the outlet from the body passage to the spray head;
• delivering the air connected to the spray head to an atomizing air orifice and shaping air orifices in the spray head for flow of high volume low pressure air through the atomizing air orifice to atomize the emitted coating material into a spray and through the shaping air orifices for impingement against and to shape the spray;
• adjusting the volume flow rate of air delivered to the shaping air orifices to adjust the shape of the spray;
• and, in response to and concurrently with performance of said adjusting step, correspondingly changing the volume flow rate of high volume low pressure air connected to the spray head from the body passage outlet to prevent the pressure of air at the spray head from exceeding a selected maximum pressure as a result of changes in the flow rate of air delivered to the shaping air orifices.

Apparatus for spray coating, comprising a spray head having a fluid orifice, an atomizing air orifice and shaping air orifices;

• means for providing liquid coating material to said fluid orifice for emission therefrom;
• air supply passage means for supplying air to said spray head;
• means for delivering air from said air supply passage means to said atomizing air orifice to atomize emitted coating liquid into a spray;
• means for selectively delivering air from said air supply passage means to said shaping air orifices for impingement against and to shape the spray;
• means for adjusting the volume flow rate of air delivered to said shaping air orifices to adjust the shape of the spray;
• and means, responsive to operation of said adjusting means, for concurrently and correspondingly adjustably controlling the volume flow rate of air through said air supply passage means to prevent the pressure of air at said spray head from exceeding a selected maximum pressure as a result of changes in the volume flow rate of air delivered to said shaping air orifices.

Apparatus for spray coating, comprising a spray head having a fluid orifice, first passageway means extending to an atomizing air orifice and second passageway means extending to shaping air orifices;

• means for delivering liquid coating material to said fluid orifice for emission therefrom;
• means for supplying air through a common air passageway means to said spray head for delivery through said first passageway means to said atomizing air orifice to atomize emitted coating material into a spray and through said second passageway means to said shaping air orifices for impingement against and to shape the spray;
• means for adjusting the air flow area through said second passageway means to control the volume flow rate of air to said shaping air orifices to adjust the shape of the spray;
• and means, responsive to operation of said adjusting means, for concurrently and correspondingly changing the air flow area through said common passageway means to change the volume flow rate of air supplied to said spray head so that the pressure of air at said spray head does not exceed a selected maximum pressure as a result of changes in the volume flow rate of air delivered to said shaping air orifices.

Apparatus for spray coating, comprising a body having an air passage therethrough;

• a spray head carried by said body, said spray head having a fluid orifice, an atomizing air orifice and shaping air orifices;
• means for delivering liquid coating material to said spray head fluid orifice for emission therefrom;
• means for supplying air at a low volume and high pressure to an inlet to said body air passage;
• means for converting the low volume high pressure air at said body passage inlet to high volume low pressure air at an outlet from said body passage;
• means for connecting the high volume low pressure air at said body passage outlet to said spray head;
• means for delivering high volume low pressure air connected to said spray head to said atomizing air orifice and to said shaping air orifices for flow through said atomizing air orifice to atomize emitted coating liquid into a spray and through said shaping air orifices for impingement against and to shape the spray;
• means for adjusting the volume flow rate of air delivered to said shaping air orifices to adjust the shape of the spray;
• and means, responsive to operation of said adjusting means, for concurrently and correspondingly changing the volume flow rate of high volume low pressure air at said body air passage outlet to prevent the pressure of air at said spray head from exceeding a selected maximum pressure as a result of changes in the volume flow rate of air delivered to said shaping air orifices.

A spray gun for atomizing liquid coating material, comprising a spray gun body having an air passage extending between an inlet to and an outlet from said passage;

• a spray head carried on said body, said spray head having a fluid orifice, an atomizing air orifice having inlet means thereto and shaping air orifices having inlet means thereto, each said inlet means being in communication with said body passage outlet;
• a restriction in said body passage, said restriction having an air flow passage therethrough;
• valve means for simultaneously adjusting the resistance to a flow of air through each of said air flow passage in said restriction and said inlet means to said shaping air orifices;
• means for delivering liquid coating material to said spray head fluid orifice for emission therefrom;
• means for supplying low volume high pressure air to said body air passage inlet for flow through said restriction to said air passage outlet, said restriction converting the low volume high pressure air at said body air passage inlet to high volume low pressure air at said body air passage outlet for flow through each of said spray head inlet means to and through said atomizing air orifice to atomize emitted coating material into a spray and to and through said shaping air orifices for impingement against and to shape the spray;
• and means for operating said valve means to simultaneously adjust the resistance to a flow of air through each of said restriction air flow passage and said inlet means to said shaping air orifices, such that the resistances to a flow of air simultaneously either increases or decreases.