Extruder
An extruder includes a cylinder and a screw that is accommodated in the cylinder, in which an inner peripheral surface of the cylinder includes first and second groove formed regions each of which has a groove formed therein, in the first groove formed region, a height of a mountain portion forming the groove is constant, and a presence range of the second groove formed region in an axial direction at least partially overlaps a presence range of a material feed port in the axial direction, and a height of a mountain portion forming the groove in the second groove formed region is lower than the height of the mountain portion of the first groove formed region.
1 . An extruder comprising:
a cylinder; and
a screw that is accommodated in the cylinder,
wherein an inner peripheral surface of the cylinder includes first and second groove formed regions each of which has a groove formed therein,
in the first groove formed region, a height of a mountain portion forming the groove is constant,
a presence range of the second groove formed region in an axial direction at least partially overlaps a presence range of a material feed port in the axial direction, and a height of a mountain portion forming the groove in the second groove formed region is lower than the height of the mountain portion of the first groove formed region, and
in a section perpendicular to the axial direction, the mountain portion formed in the second groove formed region is higher as the mountain portion is farther from the material feed port.
2 . The extruder according to claim 1 ,
wherein the second groove formed region is provided close to the material feed port in a circumferential direction.
3 . The extruder according to claim 2 ,
wherein the inner peripheral surface of the cylinder further includes a second groove formed region different from the second groove formed region, and
the different second groove formed region is provided close to the material feed port in the circumferential direction and on an opposite side to the second groove formed region with respect to the material feed port.
4 . The extruder according to claim 1 ,
wherein the second groove formed region extends to a downstream side of the material feed port in the axial direction.
5 . An extruder comprising:
a cylinder; and
a screw that is accommodated in the cylinder,
wherein an inner peripheral surface of the cylinder includes a first-groove formed region, a first second-groove formed region, and a second second-groove formed region each of which has a groove formed therein,
in the first-groove formed region, a height of a mountain portion forming the groove is constant,
a presence range of each of the first second-groove formed region and the second second-groove formed region in an axial direction at least partially overlaps a presence range of a material feed port in the axial direction, and a height of a mountain portion forming the groove in each of the first second-groove formed region and the second second-groove formed region is lower than the height of the mountain portion of the first-groove formed region,
the first second-groove formed region is provided close to the material feed port in a circumferential direction,
the second second-groove formed region is provided close to the material feed port in the circumferential direction and on an opposite side of the first second-groove formed region with respect to the material feed port,
the first-groove formed region includes a first circumferential portion and a second circumferential portion which are provided on opposite sides in the circumferential direction with respect to the material feed port,
the first circumferential portion, the second circumferential portion, the first second-groove formed region, and the second second-groove formed region are provided at the same axial position, and
the first second-groove formed region is provided between the first circumferential portion and the material feed port in the circumferential direction, and the second second-groove formed region is provided between the second circumferential portion and the material feed port in the circumferential direction.