Gas concentration meter, control method of gas concentration meter, lamination molding apparatus, and control method of oxygen concentration meter for lamination molding apparatus

A lamination molding apparatus to form a molded object, comprising:

• a chamber configured to cover a molding region in which a desired three-dimensional molded object is formed;
• an inert gas supply device configured to fill the chamber with an inert gas;
• and
• an oxygen concentration meter configured to detect an oxygen concentration in the chamber, wherein the oxygen concentration meter comprises:
• a first oxygen concentration detection sensor configured to detect at least the oxygen concentration in a first concentration range,
• a second oxygen concentration detection sensor configured to detect at least the oxygen concentration in a second concentration range, wherein an upper limit value of the second concentration range is lower than an upper limit value of the first concentration range, and a lower limit value of the second concentration range is lower than a lower limit value of the first concentration range,
• a control unit, when the supply of the inert gas in the chamber is started by the inert gas supply device, configured to:
• output an indication value based on an output signal of the first oxygen concentration detection sensor when an output signal of the first oxygen concentration detection sensor indicates an oxygen concentration in the first concentration range,
• output an indication value based on an output signal of the second oxygen concentration detection sensor when an output signal of the second oxygen concentration detection sensor indicates an oxygen concentration in the second concentration range and an output signal of the first oxygen concentration detection sensor indicates an oxygen concentration lower than the lower limit value of the first concentration range, and
• output either the lower limit value of the first concentration range or the upper limit value of the second concentration range as an indication value for a predetermined time when an output signal of the first oxygen concentration detection sensor indicates an oxygen concentration lower than the lower limit value of the first concentration range and an output signal of the second oxygen concentration detection sensor indicates an oxygen concentration higher than the upper limit value of the second concentration range, and
• an indication value display unit configured to display the indication value output from the control unit;
• wherein
• the first and second oxygen concentration detection sensors, and the indication value display unit are connected to the control unit.

A control method of a gas concentration meter for detecting a gas concentration of a specific gas in a chamber, comprising:

• detecting at least the gas concentration in a first concentration range by a first gas concentration detection sensor;
• detecting at least the gas concentration in a second concentration range by a second gas concentration detection sensor, wherein an upper limit value of the second concentration range is lower than an upper limit value of the first concentration range, and a lower limit value of the second concentration range is lower than a lower limit value of the first concentration range;
• outputting an indication value based on an output signal of the first gas concentration detection sensor when an output signal of the first gas concentration detection sensor indicates a gas concentration in the first concentration range and an output signal of the second gas concentration detection sensor indicates a gas concentration higher than the upper limit value of the second concentration range;
• outputting an indication value based on an output signal of the second gas concentration detection sensor when an output signal of the second gas concentration detection sensor indicates a gas concentration in the second concentration range and an output signal of the first gas concentration detection sensor indicates a gas concentration lower than the lower limit value of the first concentration range;
• outputting an indication value based on an output signal of either the first gas concentration detection sensor or the second gas concentration detection sensor when an output signal of the first gas concentration detection sensor indicates a gas concentration in the first concentration range and an output signal of the second gas concentration detection sensor indicates a gas concentration in the second concentration range;
• outputting either the lower limit value of the first concentration range or the upper limit value of the second concentration range as an indication value when an output signal of the first gas concentration detection sensor indicates a gas concentration lower than the lower limit value of the first concentration range and an output signal of the second gas concentration detection sensor indicates a gas concentration higher than the upper limit value of the second concentration range;
• and
• displaying the indication value output at an indication value display unit.

A control method of an oxygen concentration meter for a lamination molding apparatus, comprising:

• supplying an inert gas from an inert gas supply device into a chamber configured to cover a molding region where a desired three-dimensional molded object is formed;
• detecting at least an oxygen concentration in a first concentration range in the chamber with a first oxygen concentration detection sensor;
• detecting at least an oxygen concentration in a second concentration range in the chamber with a second oxygen concentration detection sensor, wherein an upper limit value of the second concentration range is lower than an upper limit value of the first concentration range, and a lower limit value of the second concentration range is lower than a lower limit value of the first concentration range;
• when the supply of the inert gas in the chamber is started by the inert gas supply device,
• outputting an indication value based on an output signal of the first oxygen concentration detection sensor when an output signal of the first oxygen concentration detection sensor indicates an oxygen concentration in the first concentration range,
• outputting an indication value based on an output signal of the second oxygen concentration detection sensor when an output signal of the first oxygen concentration detection sensor indicates an oxygen concentration lower than the lower limit value of the first concentration range and an output signal of the second oxygen concentration detection sensor indicates an oxygen concentration in the second concentration range, and
• outputting either the lower limit value of the first concentration range or the upper limit value of the second concentration range as an indication value for a predetermined time when an output signal of the first oxygen concentration detection sensor indicates an oxygen concentration lower than the lower limit value of the first concentration range and an output signal of the second oxygen concentration detection sensor indicates an oxygen concentration higher than the upper limit value of the second concentration range;
• and
• displaying the indication value on the indication value display unit.