Resin cutting apparatus, pelletizer, and method of controlling resin cutting apparatus

A method of controlling a resin cutting apparatus configured to manufacture pellets by cutting a resin discharged from an extruder by a plurality of cutter blades, the method comprising a step of performing a grinding process on each of the plurality of cutter blades before performing an operation to cut the resin into the pellets,

• wherein the step of performing the grinding process includes:
• (a) a step of bringing the plurality of cutter blades into contact with a die provided on a resin discharge side of the extruder based on an output from a forward/backward movement control position sensor used to control forward and backward movement of a rotating shaft attached to a cutter head in which the plurality of cutter blades are arranged and an output from a wear amount detection position sensor;
• (b) after the step (a), a step of acquiring a first position of the cutter head based on the output from the wear amount detection position sensor;
• (c) after the step (b), a step of performing the grinding process for a predetermined period of time;
• (d) after the step (c), a step of acquiring a second position of the cutter head based on the output from the wear amount detection position sensor;
• (e) after the step (d), a step of calculating a difference between the first position and the second position;
• and
• (f) after the step (e), a step of comparing the difference and a predetermined setting value to judge whether or not to end the grinding process.

A resin cutting apparatus comprising:

• a die provided on a resin discharge side of an extruder;
• a plurality of nozzles provided in the die;
• a plurality of cutter blades configured to cut a resin discharged from the plurality of nozzles into pellets;
• a cutter head in which the plurality of cutter blades are arranged;
• a rotating shaft attached to the cutter head;
• a motor configured to rotate the rotating shaft;
• a flow path chamber constituting a flow path space that is in contact with the cutter head;
• an inlet through which a fluid flows into the flow path chamber;
• an outlet through which the fluid and the pellets flow out of the flow path chamber;
• a control unit configured to control a cutter blade pressing force for pressing the plurality of cutter blades to the die;
• a rotating shaft forward force generating unit configured to generate a rotating shaft forward force on the rotating shaft;
• a rotating shaft backward force generating unit configured to generate a rotating shaft backward force on the rotating shaft;
• a forward/backward movement control position sensor configured to control forward and backward movement of the rotating shaft;
• and
• a wear amount detection position sensor configured to detect a wear amount of the plurality of cutter blades,
• wherein the control unit controls a magnitude of the rotating shaft backward force applied to the rotating shaft based on an output from the wear amount detection position sensor.

A resin cutting apparatus comprising:

• a die provided on a resin discharge side of an extruder;
• a plurality of nozzles provided in the die;
• a plurality of cutter blades configured to cut a resin discharged from the plurality of nozzles into pellets;
• a cutter head in which the plurality of cutter blades are arranged;
• a rotating shaft attached to the cutter head;
• a motor configured to rotate the rotating shaft;
• a flow path chamber constituting a flow path space that is in contact with the cutter head;
• an inlet through which a fluid flows into the flow path chamber;
• an outlet through which the fluid and the pellets flow out of the flow path chamber;
• a control unit configured to control a cutter blade pressing force for pressing the plurality of cutter blades to the die;
• a rotating shaft forward force generating unit configured to generate a rotating shaft forward force on the rotating shaft;
• a rotating shaft backward force generating unit configured to generate a rotating shaft backward force on the rotating shaft;
• a forward/backward movement control position sensor configured to control forward and backward movement of the rotating shaft;
• and
• a wear amount detection position sensor configured to detect a wear amount of the plurality of cutter blades,
• wherein the control unit includes a grinding control unit configured to control a grinding process performed on each of the plurality of cutter blades before performing an operation of cutting the resin into the pellets, and
• wherein the grinding control unit includes:
• a first position acquisition unit configured to acquire a first position of the cutter head based on an output from the wear amount detection position sensor;
• a second position acquisition unit configured to acquire a second position of the cutter head after performing the grinding process for a predetermined period of time, based on the output from the wear amount detection position sensor;
• a difference calculation unit configured to calculate a difference between the first position and the second position;
• a comparison unit configured to compare the difference and a predetermined setting value;
• and
• a judgment unit configured to judge whether to end the grinding process based on a comparison result between the difference and the setting value.

A pelletizer comprising:

• an extruder;
• and
• a resin cutting apparatus configured to cut a resin extruded from the extruder into pellets,
• wherein the resin cutting apparatus includes:
• a die provided on a resin discharge side of the extruder;
• a plurality of nozzles provided in the die;
• a plurality of cutter blades configured to cut the resin discharged from the plurality of nozzles into the pellets;
• a cutter head in which the plurality of cutter blades are arranged;
• a rotating shaft attached to the cutter head;
• a motor configured to rotate the rotating shaft;
• a flow path chamber constituting a flow path space that is in contact with the cutter head;
• an inlet through which a fluid flows into the flow path chamber;
• an outlet through which the fluid and the pellets flow out of the flow path chamber;
• a control unit configured to control a cutter blade pressing force for pressing the plurality of cutter blades to the die;
• a rotating shaft forward force generating unit configured to generate a rotating shaft forward force on the rotating shaft;
• a rotating shaft backward force generating unit configured to generate a rotating shaft backward force on the rotating shaft;
• a forward/backward movement control position sensor configured to control forward and backward movement of the rotating shaft;
• and
• a wear amount detection position sensor configured to detect a wear amount of the plurality of cutter blades, and
• wherein the control unit controls a magnitude of the rotating shaft backward force applied to the rotating shaft based on an output from the wear amount detection position sensor.

A pelletizer comprising:

• an extruder;
• and
• a resin cutting apparatus configured to cut a resin extruded from the extruder into pellets,
• wherein the resin cutting apparatus includes:
• a die provided on a resin discharge side of the extruder;
• a plurality of nozzles provided in the die;
• a plurality of cutter blades configured to cut the resin discharged from the plurality of nozzles into the pellets;
• a cutter head in which the plurality of cutter blades are arranged;
• a rotating shaft attached to the cutter head;
• a motor configured to rotate the rotating shaft;
• a flow path chamber constituting a flow path space that is in contact with the cutter head;
• an inlet through which a fluid flows into the flow path chamber;
• an outlet through which the fluid and the pellets flow out of the flow path chamber;
• a control unit configured to control a cutter blade pressing force for pressing the plurality of cutter blades to the die;
• a rotating shaft forward force generating unit configured to generate a rotating shaft forward force on the rotating shaft;
• a rotating shaft backward force generating unit configured to generate a rotating shaft backward force on the rotating shaft;
• a forward/backward movement control position sensor configured to control forward and backward movement of the rotating shaft;
• and
• a wear amount detection position sensor configured to detect a wear amount of the plurality of cutter blades,
• wherein the control unit includes a grinding control unit configured to control a grinding process performed on each of the plurality of cutter blades before performing an operation of cutting the resin into the pellets, and
• wherein the grinding control unit includes:
• a first position acquisition unit configured to acquire a first position of the cutter head based on an output from the wear amount detection position sensor;
• a second position acquisition unit configured to acquire a second position of the cutter head after performing the grinding process for a predetermined period of time, based on the output from the wear amount detection position sensor;
• a difference calculation unit configured to calculate a difference between the first position and the second position;
• a comparison unit configured to compare the difference and a predetermined setting value;
• and
• a judgment unit configured to judge whether to end the grinding process based on a comparison result between the difference and the setting value.