Method and apparatus for controlling movement of cutting blade and workpiece

A method of controlling a relative movement of a cutting blade and a workpiece which are moved relative to each other by a movement device in an operation with a machine tool, said method comprising a step of bringing said cutting blade and an object into contact with each other, by moving at least one of said cutting blade and said object toward each other by said movement device, and a step of controlling said relative movement on the basis of a relative position of said cutting blade and said object which is detected by said movement device upon said contact of said cutting blade and said object with each other, said method further comprising:

• a first-circuit preparing step of preparing a first circuit which includes said object and said cutting blade arranged in series to each other and which is connected to a power source, said first circuit being closed when said cutting blade and said object are in contact with each other, while being open when said cutting blade and said object are not in contact with each other;
• a second-circuit preparing step of preparing a second circuit which includes a resistance and which is connected in parallel with said first circuit, said second circuit being closed irrespective of whether said cutting blade and said object are in contact with each other or not;
• a checking step of detecting a state of said power source by a power source detector when said first circuit is open, and checking if each of said power source and said power source detector is in a normal condition;
• and
• a contact-position determining step of determining, as a contact position in which said cutting blade and said object are brought into contact with each other, said relative position of said cutting blade and said object when said state of said power source detected by said power source detector indicates transition from an open state in which said first circuit is open, to a closed state in which said first circuit is closed.

A method of controlling a relative movement of a cutting blade and a workpiece which are moved relative to each other by a movement device in an operation with a machine tool, said method comprising a step of bringing said cutting blade and an object into contact with each other, by moving at least one of said cutting blade and said object toward each other by said movement device, and a step of controlling said relative movement on the basis of a relative position of said cutting blade and said object which is detected by said movement device upon said contact of said cutting blade and said object with each other, said method further comprising:

• a resistance-circuit preparing step of preparing a resistance circuit in which said object and said cutting blade are connectable to each other via a first resistance which has a predetermined first resistance value;
• a checking step of checking, with a checking device, if a value of an electric resistance acting between said object and said cutting blade is substantially equal to said predetermined first resistance value of said first resistance when said cutting blade and said object are not in contact with each other;
• and
• a contact determining step of determining that said cutting blade and said object have been brought into contact with each other when said value of said electric resistance acting between said object and said cutting blade is reduced to be smaller than a predetermined second resistance value which is smaller than said first resistance value.

An apparatus for controlling a relative movement of a cutting blade and a workpiece which are moved relative to each other by a movement device in an operation with a machine tool, said apparatus controlling said relative movement on the basis of a relative position of said cutting blade and an object which is detected by said movement device when said cutting blade and said object are brought into contact with each other as a result of a relative movement of said cutting blade and said object which is made by said movement device, said apparatus comprising:

• a first circuit which includes said object and said cutting blade arranged in series to each other and which is connected to a power source, said first circuit being closed when said cutting blade and said object are in contact with each other, while being open when said cutting blade and said object are not in contact with each other;
• a second circuit which includes a resistance and which is connected in parallel with said first circuit, said second circuit being closed irrespective of whether said cutting blade and said object are in contact with each other or not;
• a power source detector which detects a state of said power source;
• and
• a control device which commands said movement device to move said cutting blade and said object relative to each other if each of said power source and said power source detector is indicated normal by said power source detector when said first circuit is open, said control device controlling said movement device on the basis of said relative position of said cutting blade and said object which is detected by said movement device when said state of said power source detected by said power source detector indicates transition from an open state in which said first circuit is open, to a closed state in which said first circuit is closed.

A method of detecting contact and separation of a cutting blade held by a blade holding member, with and from an object, on the basis of a change of a state of an electric circuit which is changed depending upon whether said cutting blade is in contact with said object or is separated from said object, said method comprising:

• a step of bringing said cutting blade and said object into contact with each other, while a conductive layer having electrical conductivity is provided in at least one of a space between said cutting blade and said blade holding member, and a space between said cutting blade and said object;
• wherein said conductive layer consists of a resistive coating which covers at least a cutting edge of said cutting blade and an adjacent portion of said cutting blade which portion is adjacent to said cutting edge, said method further comprising:
• a cutting-blade identifying step of determining that said cutting blade is a currently required cutting blade if said state of said electric circuit satisfies a predetermined condition when said cutting blade is in contact with said object via said resistive coating, and determining that said cutting blade is not the currently required cutting blade if said state of said electric circuit does not satisfy said predetermined condition when said cutting blade is in contact with said object via said resistive coating, said predetermined condition including at least one of a current-value-related requirement that a value of electric current flowing through said electric circuit upon contact of said cutting blade with said object via said resistive coating is held in a predetermined range, and a resistance-value-related requirement that a value of electric resistance acting on said electric circuit upon said contact is held in a predetermined range.

A method of detecting contact and separation of a cutting blade held by a blade holding member, with and from an object, on the basis of a change of a state of an electric circuit which is changed depending upon whether said cutting blade is in contact with said object or is separated from said object, said method comprising:

• a step of bringing said cutting blade and said object into contact with each other, while a conductive layer having electrical conductivity is provided in at least one of a space between said cutting blade and said blade holding member, and a space between said cutting blade and said object;
• wherein said conductive layer consists of a resistive coating which covers at least a contact surface of said cutting blade that is held in contact with said blade holding member, said method further comprising:
• a cutting-blade identifying step of determining that said cutting blade is a currently required cutting blade if said state of said electric circuit satisfies a predetermined condition when said cutting blade is in contact with said object via said resistive coating, and determining that said cutting blade is not the currently required cutting blade if said state of said electric circuit does not satisfy said predetermined condition when said cutting blade is in contact with said object via said resistive coating, said predetermined condition including at least one of a current-value-related requirement that a value of electric current flowing through said electric circuit upon contact of said cutting blade with said object via said resistive coating is held in a predetermined range, and a resistance-value-related requirement that a value of electric resistance acting on said electric circuit upon said contact is held in a predetermined range.

A method of detecting contact and separation of a cutting blade held by a blade holding member, with and from an object, on the basis of a change of a state of an electric circuit which is changed depending upon whether said cutting blade is in contact with said object or is separated from said object, said method comprising:

• a step of bringing said cutting blade and said object into contact with each other, while a conductive layer having electrical conductivity is provided in at least one of a space between said cutting blade and said blade holding member, and a space between said cutting blade and said object;
• wherein said cutting blade held by said blade holding member includes a cutting edge, an adjacent portion adjacent to said cutting edge and a contact surface held in contact with said blade holding member, and wherein at least said cutting edge, said adjacent portion and said contact surface of said cutting blade are covered with a conductive coating as said conductive layer, said method further comprising:
• a moving step of moving at least one of said cutting blade and said object toward each other such that said cutting edge is brought into contact with said object via said conductive coating;
• a memorizing step of memorizing, as a contact position, a relative position of said cutting blade and said object upon contact of said cutting edge with said object via said conductive coating;
• a movement-controlling step of controlling a relative movement of said cutting blade and a workpiece which is to be cut by said cutting blade and a workpiece which is to be cut by said cutting blade, on the basis of said contact position memorized in said memorizing step;
• and
• a cutting-blade identifying step of determining that said cutting blade is not a currently required cutting blade if said state of said electric circuit including said workpiece, said cutting blade and said blade holding member which are arranged in series to each other, does not satisfy a predetermined condition when said conductive coating covering said cutting edge is destroyed due to contact of said cutting blade with said workpiece as a result of said relative movement of said cutting blade and said workpiece, wherein said predetermined condition includes at least one of a current-value-related requirement that a value of electric current flowing through said electric circuit upon destruction of said conductive coating is held in a predetermined range, and a resistance-value-related requirement that a value of electric resistance acting on said electric circuit upon destruction of said conductive coating is held in a predetermined range, said predetermined condition being determined to be not satisfied if said at least one of said current-value-related requirement and said resistance-value-related requirement is not satisfied.

A method of identifying a plurality of cutting blades each including a cutting edge and an adjacent portion which is adjacent to said cutting edge, comprising:

• a covering step of covering at least said cutting edge and said adjacent portion of each of said cutting blades with a resistive coating made of a material, which is selected among a plurality of materials having respective electric resistance values different from each other, depending upon a kind of each of said cutting blades;
• a blade setting step of setting one of said cutting blades in a blade holding member such that said one of said cutting blades is held by said blade holding member, for thereby forming an electric circuit including said one cutting blade, said blade holding member and an object which is contactable with and separable away from said cutting blade and which is arranged in series with said one cutting blade and said blade holding member;
• and
• a blade identifying step of identifying a kind of said one cutting blade which is currently held by said blade holding member, on the basis of a state of said electric circuit when said cutting edge of said cutting blade is in contact with said object via said resistive coating.

A method of identifying a plurality of cutting blades each including a cutting edge and a contact surface which is held in contact with a blade holding member, comprising:

• a covering step of covering at least said contact surface of each of said cutting blades with a resistive coating made of a material, which is selected among a plurality of materials having respective electric resistance values different from each other, depending upon a kind of each of said cutting blades;
• a blade setting step of setting one of said cutting blades in a blade holding member such that said one of said cutting blades is held at said contact surface by said blade holding member, for thereby forming an electric circuit including said one cutting blade, said blade holding member and an object which is contactable with and separable away from said cutting blade and which is arranged in series with said one cutting blade and said blade holding member;
• and
• a blade identifying step of identifying a kind of said one cutting blade which is currently held by said blade holding member, on the basis of a state of said electric circuit when said cutting edge of said cutting blade is in contact with said object.