Glass plate cutting method and glass plate cutting machine

A glass plate cutting machine comprising:

• a cutter blade for forming a cut line on a glass plate, said cut line including a round line portion and a straight line portion;
• moving means for moving said cutter blade along the cut line which has been preset and is to be formed on the glass plate;
• a resilient pressing device for resiliently pressing said cutter blade against the glass plate by air pressure;
• and a control unit for controlling said resilient pressing device so as to resiliently press said cutter blade against the glass plate by the air pressure, whose intensity is alternately changed over, imparted thereto,
• said resilient pressing device including an air cylinder unit for pressing the cutter blade against the glass plate by a resilient pressing force caused by the air pressure supplied thereto, a first resilient pressing force generating device having a first air pressure source for generating a first air pressure for imparting a first resilient pressing force to said cutter blade, a second resilient pressing force generating device having a second air pressure source for generating a second air pressure which is different from the first air pressure for imparting a second resilient pressing force, an intensity of which is different from that of the first resilient pressing force, to said cutter blade, and a valve mechanism for communicating the first and second air pressure sources alternately to the air cylinder unit, and
• said control unit is adapted to control the valve mechanism such that the time interval for alternately changing over the intensity of the air pressure at the round line portion becomes shorter than the time interval for alternately changing over the intensity of the air pressure at the straight line portion.

A glass plate cutting machine comprising:

• a cutter blade for forming a cut line on a glass plate, said cut line including a first cut line on the glass plate and a second cut line successively connected in series to the first cut line on the glass plate;
• moving means for moving said cutter blade along the cut line which has been preset and is to be formed on the glass plate;
• a resilient pressing device for resiliently pressing said cutter blade against the glass plate by air pressure;
• and a control unit for controlling said resilient pressing device so as to alternately change over a resilient pressing force of said cutter blade by the air pressure with respect to the glass plate in the movement of said cutter blade by said moving means,
• said resilient pressing device including an air cylinder unit for pressing the cutter blade against the glass plate by the resilient pressing force caused by the air pressure supplied thereto, a first resilient pressing force generating device having a first air pressure source for generating a first air pressure for imparting a first resilient pressing force to said cutter blade, a second resilient pressing force generating device having a second air pressure source for generating a second air pressure which is different from the first air pressure for imparting a second resilient pressing force, an intensity of which is different from that of the first resilient pressing force, to said cutter blade, and a valve mechanism for communicating the first and second air pressure sources alternately to the air cylinder unit, and
• said control unit is adapted to control the valve mechanism so as to form the cut line on the glass plate in the movement of said cutter blade by continuously repeatedly effecting a cut line forming step of forming the cut line on the glass plate in the movement of said cutter blade, said cut line forming step having a first step of pressing the glass plate by said cutter blade with the first resilient pressing force with respect to the glass plate to form the first cut line on the glass plate by said cutter blade, and a second step of pressing the glass plate by said cutter blade with the second resilient pressing force with respect to the glass plate to form the second cut line successively connected in series to the first cut line on the glass plate by said cutter blade, to thereby form on the glass plate the cut line including the first and second cut lines.