Pull roll assembly for drawing a glass sheet

A pull roll assembly comprising:

• a first roll assembly including:
• a first pulling roll support arm;
• a first motor;
• and
• a first roll;
• said first pulling roll support arm includes a frame supported by a horizontal restraint that is configured to transmit a horizontal load on said frame directly to an arm that is attached to one end of the frame, where a load cell is attached to the arm to measure the horizontal load which is caused by a glass sheet interfacing with said first roll that is rotatably attached to said frame and said first roll is also driven by said first motor;
• said frame further includes a pivot point where a spring is located and when a vertical load is present the first roll moves in a downward direction which changes a gap between said spring and a gap sensor, wherein the gap sensor measures a distance of the gap which is directly related to a distance the first roll moves in the downward direction and to the vertical load which is caused by the glass sheet interfacing with said first roll that is rotatably attached to said frame, and wherein the horizontal restraint is configured to transmit the horizontal load on the frame directly to the arm without effecting the vertical load on the spring;
• and
• a second roll assembly including:
• a second pulling roll support arm;
• a second motor, and
• a second roll;
• and
• said load cell and said gap sensor enables one to control at least the first motor while the glass sheet is being drawn between the first and second rollers, wherein the control of at least the first motor is based in part to substantially maintain a required sheet pulling force associated with the glass sheet while the glass sheet is being drawn between the first and second rollers, wherein the required sheet pulling force includes a force supplied to the glass sheet and a force associated with a weight of the glass sheet where the weight changes because a part of the drawn glass sheet is cut and removed therefrom, wherein said load cell and said gap sensor by enabling the control of at least the first motor to substantially maintain the required sheet pulling force helps prevent either or both of the first and second rolls from slipping on one or more surfaces of the glass sheet.

A method for producing a glass sheet, said method comprising the steps of:

• melting batch materials to form the glass sheet;
• delivering the glass sheet to a fusion draw machine;
• and
• drawing the glass sheet using the fusion draw machine which comprises:
• a first roll assembly including:
• at least one pulling roll support arm;
• a first constant rotational drive motor;
• a first roll:
• and
• a first torque sensor;
• a second roll assembly including:
• at least one pulling roll support arm;
• a second constant torque motor;
• and
• a second roll;
• and
• using the first torque sensor to measure torque being delivered to the glass sheet as the glass sheet is drawn between the first and second rolls while the first constant rotational drive motor is driving the first roll and the second constant torque motor is not driving the second roll;
• and
• using the measured torque to determine how much torque is to be subsequently applied by the second constant torque motor to the second roll such that both the first roll and the second roll share a load in drawing the glass sheet.

A method for producing a glass sheet, said method comprising the steps of:

• melting batch materials to form the glass sheet;
• delivering the glass sheet to a fusion draw machine;
• and
• drawing the glass sheet using the fusion draw machine which comprises:
• a first roll assembly including:
• a first pulling roll support arm;
• a first motor;
• and
• a first roll;
• said first pulling roll support arm includes a frame supported by a horizontal restraint that is configured to transmit a horizontal load on said frame directly to an arm that is attached to one end of the frame, where a load cell is attached to the arm to measure the horizontal load which is caused by the glass sheet interfacing with said first roll that is rotatably attached to said frame and said first roll is also driven by said first motor;
• said frame further includes a pivot point where a spring is located and when a vertical load is present the first roll moves in a downward direction which changes a gap between said spring and a gap sensor, wherein the gap sensor measures a distance of the gap which is directly related to a distance the first roll moves in the downward direction and to the vertical load which is caused by the glass sheet interfacing with said first roll that is rotatably attached to said frame, and wherein the horizontal restraint is configured to transmit the horizontal load on the frame directly to the arm without effecting the vertical load on the spring;
• and
• a second roll assembly including:
• a second pulling roll support arm;
• a second motor;
• and
• a second roll;
• and
• using the measured horizontal load form the load cell and the measured gap from the gap sensor to control at least the first motor while the glass sheet is being drawn between the first and second rollers, wherein the control of at least the first motor is based in part to substantially maintain a required sheet pulling force associated with the glass sheet while the glass sheet is being drawn between the first and second rollers, wherein the required sheet pulling force which is related to the vertical force includes a force supplied to the glass sheet and a force associated with a weight of the glass sheet where the weight changes because a part of the drawn glass sheet is cut and removed therefrom, and wherein said load cell and said gap sensor by enabling the control of at least the first motor to substantially maintain the required sheet pulling force helps prevent either or both of the first and second rolls from slipping on one or more surfaces of the glass sheet.