Patent Description:
<CIT> (Patent Document <NUM>) discloses a technique relating to a strand manufacturing apparatus including an extruder and a die. Also, a flow rate regulator for die head is disclosed in <CIT>.

Resin products, for example, resin pellets can be manufactured by using resins extruded from an extruder. It is desired to improve quality of the resin products manufactured by using the resins extruded from the extruder.

Other problems and novel features will become apparent from descriptions of the present specification and the accompanying drawings.

According to the invention, an extrusion die as claimed in independent claim <NUM> is enclosed, as well as a related extruder including such a die according to claim <NUM>; further preferred embodiments are claimed in the dependent claims.

According to the invention, the quality of the resin products manufactured by using the resins extruded from the extruder can be improved.

Hereinafter, embodiments will be described in detail with reference to the drawings. Incidentally, in all the drawings for explaining the embodiments, members having the same function are denoted by the same reference numeral, and a repetitive description thereof will be omitted. Further, in the following embodiments, a description of the same or similar part is not repeated in principle except when it is particularly necessary.

<FIG> is an explanatory drawing (side view) showing a configuration example of a pellet manufacturing system (pellet manufacturing device) <NUM> using an extruder (extrusion molding device) <NUM> of the present embodiment.

First, a schematic configuration of the extruder <NUM> will be described with reference to <FIG>. The extruder <NUM> shown in <FIG> has a cylinder (barrel) <NUM>, two screws (not shown) rotatably arranged in the cylinder <NUM>, a rotary drive mechanism <NUM> for rotating the screws in the cylinder <NUM>, a hopper (resin input portion) <NUM> arranged on an upstream side (rear end side) of the cylinder <NUM>, and a die (metal mold) <NUM> attached to a downstream-side tip of the cylinder <NUM>. The hopper <NUM> is connected to an upper surface of the cylinder <NUM> so that a resin can be supplied into the cylinder <NUM> via the hopper <NUM>. Temperature of the cylinder <NUM> is controlled by a not-shown temperature adjusting means (temperature adjusting mechanism) such as a heater. The extruder <NUM> may also have a filler supply device (not shown) connected to the cylinder <NUM> and, in this case, a desired filler(s) can be supplied into the cylinder <NUM> from the filler supply device.

Incidentally, when the extruder <NUM> is referred to as "downstream side" and "upstream side", the "downstream side" means a downstream side of a resin flow in the extruder <NUM> and the "upstream side" means an upstream side of the resin flow in the extruder <NUM>. Consequently, in the extruder <NUM>, a side of the die <NUM> near a plurality of hole portions <NUM> described later is a downstream side, and a side of the die <NUM> far from the plurality of hole portions <NUM>, that is, a side close to the hopper <NUM> is an upstream side.

The two screws (not shown) are rotatably inserted and built into the cylinder <NUM>. Consequently, the extruder <NUM> can also be regarded as a twin-screw extruder (two-screw extrusion device). In the cylinder <NUM>, the two screws are arranged and rotate so as to mesh with each other. A longitudinal direction of the cylinder <NUM> (long-side direction, axial direction, extending direction) and a longitudinal direction of the screw in the cylinder <NUM> (long-side direction, axial direction, extending direction) are the same.

The die <NUM> can function to form a molten resin extruded from the cylinder <NUM> of the extruder <NUM> into a predetermined cross-sectional shape (here, a string shape) and discharge the molten resin. Consequently, the die <NUM> is an extrusion die (metal mold).

The pellet manufacturing system <NUM> shown in <FIG> further includes a cooling tank <NUM> and a cutting device <NUM> in addition to the extruder <NUM>.

Next, an outline of an operation of the pellet manufacturing system <NUM> including the extruder <NUM> shown in <FIG> will be described.

In the extruder <NUM>, the resin (thermoplastic resin) supplied from the hopper <NUM> into the cylinder <NUM> is melted (that is, becomes a molten resin) while being sent forward by rotation of the screws in the cylinder <NUM>. When the filler is supplied into the cylinder <NUM> from the filler supply device (not shown), the resin (molten resin) and the filler are kneaded in the cylinder <NUM> of the extruder <NUM> by the rotation of the screws, so that the molten resin in the cylinder <NUM> becomes a state of containing the filler.

In the extruder <NUM>, the molten resin sent forward in the cylinder <NUM> by the rotation of the screws is extruded from the die <NUM> attached to a tip of the cylinder <NUM>. At this time, the molten resin is formed into a string shape by the die <NUM> and is extruded as a strand (resin strand) <NUM> from the die <NUM>. The strand <NUM> extruded from the die <NUM> of the extruder <NUM> is cooled in the cooling tank <NUM> and is solidified (coagulated). The solidified strand <NUM> is cut to a predetermined length by the cutting device <NUM>. Thus, pellets (resin pellets) <NUM> are produced. In the pellet manufacturing system <NUM>, the extruder <NUM> can function as a strand manufacturing device.

Next, a configuration of the die (metal mold) <NUM> used in the extruder <NUM> of the present embodiment will be described with reference to <FIG>. <FIG> is a front view of the extruder <NUM> of the present embodiment, and a front view of the die <NUM> attached to the tip of the cylinder <NUM> a is illustrated. <FIG> is a plan view showing a plate member <NUM> shown in <FIG>. <FIG> and <FIG> each are a sectional view of a main part of the extruder <NUM> of the present embodiment. <FIG> substantially corresponds to a sectional view taken at a position of line A1-A1 shown in <FIG>, and <FIG> substantially corresponds to a sectional view taken at a position of line A2-A2 shown in <FIG>. Further, in <FIG>, <FIG> and <FIG>, for simplification, a fixing member (screw or the like) for fixing a die member 5a to a die member 5b is omitted in figure.

Incidentally, an X direction, a Y direction, and a Z direction are shown in <FIG>, <FIG> described later, and the like. The X, Y, and Z directions are directions intersecting with one another and, more specifically, are directions orthogonal to one another. Consequently, the X direction and the Y direction are orthogonal to each other, and the Z direction is orthogonal to the X direction and the Y direction. The Y direction is a direction in which the molten resin mainly flows in a resin flow path portion <NUM> (more specifically, slit portion <NUM>). The Z direction is a thickness direction of the resin flow path portion <NUM> (more specifically, slit portion <NUM>). The X and Y directions correspond to a horizontal direction, and the Z direction corresponds to an up-and-down direction (vertical direction, height direction).

The die <NUM> has a plurality of hole portions (die hole portions, discharge ports, nozzle portions) <NUM> for discharging the strand <NUM> made of a molten resin, and a resin flow path portion <NUM> which guides, into the plurality of hole portions <NUM>, the molten resin supplied (introduced) from the cylinder <NUM>. That is, the resin flow path portion <NUM> and the plurality of hole portions <NUM> are formed in the die <NUM>. The resin flow path portion <NUM> extends in a flow path direction (here, Y direction) that leads to the plurality of hole portions <NUM> from an inflow port <NUM>. In the die <NUM>, the plurality of hole portions <NUM> are arranged in the X direction and are separated from each other. <FIG> shows a case where an arrangement of the plurality of hole portions <NUM> is in a row, but as another form, the arrangement of the plurality of hole portions <NUM> may be a staggered arrangement.

The plurality of hole portions (die hole portions) <NUM> communicate with (spatially connect with) the common resin flow path portion <NUM>. The resin flow path portion <NUM> and the plurality of hole portions <NUM> are spaces in which the molten resin supplied (introduced) to the die <NUM> can flow (move). The resin flow path portion <NUM> and the plurality of hole portions <NUM> can also be regarded as a flow path (resin flow path) that is formed in the die <NUM> and which the molten resin passes through. A periphery of a resin flow path composed of the resin flow path portion <NUM> and the plurality of hole portions <NUM> is surrounded by metal materials constituting the die <NUM>.

The plurality of hole portions <NUM> function to form, into a predetermined shape, a cross-sectional shape of the molten resin (strand <NUM>) extruded from the die <NUM>. That is, since the molten resin passes through the plurality of hole portions <NUM> and is discharged to an outside of the die <NUM>, the molten resin is formed into a predetermined cross-sectional shape by the hole portions <NUM> and is discharged from the hole portions <NUM> to the outside of the die <NUM>. For example, when the cross-sectional shape (cross-sectional shape substantially perpendicular to the extending direction of the hole portion <NUM>) of the hole portion <NUM> is circular, the cross-sectional shape (cross-sectional shape substantially perpendicular to the extending direction of the strand <NUM>) of the molten resin (strand <NUM>) discharged from the hole portion <NUM> (strand <NUM>) also becomes circular. Further, a diameter of the strand <NUM> can be controlled by a diameter of the hole portion <NUM>. However, the diameter of the strand <NUM> also changes depending on a flow velocity of the molten resin discharged from the hole portions <NUM>. The resin flow path portion <NUM> functions as a flow path (resin flow path) for guiding, into the plurality of hole portions <NUM>, the molten resin supplied from the cylinder <NUM> to the die <NUM>.

The die <NUM> is configured by a die member (die body portion) 5a and a die member (die holder portion) 5b. That is, the die <NUM> has the die member 5a and the die member 5b, and the die member 5b is attached to a tip (downstream-side tip) of the cylinder <NUM> of the extruder <NUM>, and the die member 5a is attached to a front side (a side opposite to a side connected to the cylinder <NUM>) of the die member 5b. Consequently, the die member 5a is held by the cylinder <NUM> via the die member 5b, and the die member 5b has a function of holding the die member 5a. The plurality of hole portions <NUM> are formed in the die member 5a, and the resin flow path portion <NUM> is mainly formed in the die member 5b. Thus, the die member 5b holds the die member 5a in which the plurality of hole portions <NUM> are formed, and also has a function of defining the resin flow path portion <NUM> for guiding, into the plurality of hole portions <NUM>, the molten resin from the cylinder <NUM>.

The die <NUM> may be formed of one integral member, but if the die <NUM> is formed of a plurality of members (here, die members 5a, 5b), the plurality of hole portions <NUM> and the resin flow path portion <NUM> can easily be formed, which makes a processing of the die <NUM> easy. Since the definition of the cross-sectional shape of the strand <NUM> is made by the hole portions <NUM> formed in the die member 5a, the die member 5a can be regarded as a die and the die member 5b can be regarded as a die holder portion for holding the die (die member 5a). Further, the die member 5b can be configured by a plurality of members (metal members, metal mold members) and, in that case, the die member 5b can be configured by fixing the plurality of members with fixing members such as screws or bolts.

The die <NUM> is preferably made of a metal material (s) and, therefore, the die members 5a, 5b are preferably made of metal materials. The die member 5b is fixed to the cylinder <NUM> by a fixing member (not shown) such as a screw or a bolt. Further, the die member 5a is fixed to the die member 5b by a fixing member (not shown) such as a screw or a bolt.

The die member 5b is attached to the cylinder <NUM> so that an opening (outlet of the molten resin) 2a at the tip of the cylinder <NUM> communicates with (spatially connects with) the resin flow path portion <NUM> of the die <NUM>. Consequently, the molten resin extruded from the opening 2a at the tip of the cylinder <NUM> is supplied to the resin flow path portion <NUM>, flows into the plurality of hole portions <NUM> via the resin flow path portion <NUM>, and is discharged from the plurality of hole portions <NUM> to the outside of the die <NUM>. The molten resin discharged from the plurality of hole portions <NUM> becomes the above-mentioned strand <NUM>. A longitudinal direction (long-side direction, axial direction, extending direction) of the cylinder <NUM> can be made the Y direction.

Formed in the die member 5b is a groove portion (passage portion, slide portion) <NUM> that allows the plate member (moving plate, plate portion, slide plate portion, gate portion) <NUM> to move in an up-and-down direction. The plate member <NUM> is arranged (accommodated and inserted) in the groove portion <NUM> of the die member 5b. The plate member <NUM> is inserted into the groove portion <NUM> of the die member 5b, but can move in the up-and-down direction. That is, the plate member <NUM> is inserted into the groove portion <NUM> of the die member 5b in a state of being movable in the up-and-down direction (that is, in a manner of being movable in the up-and-down direction), and the plate member <NUM> is configured to be capable of changing its height position to a desired height position. The plate member <NUM> is a plate-shaped member. Like the die members 5a, 5b, the plate member <NUM> is also preferably made of a metal material(s).

The plate member (moving plate) <NUM> is movable in the up-and-down direction (Z direction) so as to protrude toward the resin flow path portion <NUM>. The plate member <NUM> is arranged along the X direction. Both end portions of the plate member <NUM> in the X direction move in the up-and-down direction (Z direction) so as to contact with an inner wall of the resin flow path portion <NUM>.

A part of the plate member <NUM> protrudes toward the resin flow path portion <NUM>. Specifically, a tip portion (lower end portion) of the plate member <NUM> projects into the resin flow path portion <NUM> from above the resin flow path portion <NUM>. Consequently, by moving the plate member <NUM> in the up-and-down direction (Z direction) and adjusting the height position of the plate member <NUM>, a protrusion amount (t1) of the plate member <NUM> in the resin flow path portion <NUM> can be changed (controlled). That is, when the plate member <NUM> is moved downward to lower the height position of the plate member <NUM>, the protrusion amount (t1) of the plate member <NUM> in the resin flow path portion <NUM> is increased, and when the plate member <NUM> is moved upward to increase the height position of the plate member <NUM>, the protrusion amount (t1) of the plate member <NUM> in the resin flow path portion <NUM> is decreased. Although its details will be described later, a flow velocity distribution of the molten resin flowing through the resin flow path portion <NUM> can be controlled by adjusting the protrusion amount (t1) of the plate member <NUM> in the resin flow path portion <NUM>. The plate member <NUM> can also be regarded as a component of the die <NUM> and, in this case, the die <NUM> is configured by the die members 5a, 5b and the plate member <NUM>.

The plate member <NUM> is coupled to a slide bar <NUM> by the fixing portion <NUM>. The slide bar <NUM> is a rod-shaped member, preferably made of a metal material. A support member <NUM> is attached to the die member 5b, and the slide bar <NUM> passes through an opening of the support member <NUM>. Consequently, a moving direction of the slide bar <NUM> can be defined as an up-and-down direction. The slide bar <NUM> is movable in the up-and-down down, and moving the slide bar <NUM> in the up-and-down direction makes it possible to move in the up-and-down direction the plate member <NUM> inserted in the groove portion <NUM> of the die member 5b. Any mechanism can be used as a mechanism for moving the slide bar <NUM> in the up-and-down direction. For example, the slide bar <NUM> can be moved in the up-and-down direction by a hydraulic cylinder or the like. Alternatively, the slide bar <NUM> can be moved in the up-and-down direction by rotating a screw member coupled to the slide bar <NUM>.

Next, a detailed configuration of the resin flow path portion <NUM> will be described with reference to <FIG>. <FIG> are plan views each showing the resin flow path portion <NUM> and the plurality of hole portions <NUM> formed in the die <NUM>. Each of <FIG> is a sectional view of a main part of the die <NUM>. In <FIG>, the flow of the molten resin in the resin flow path portion <NUM> is schematically shown by arrows. Further, in <FIG>, a position of the plate member <NUM> protruding toward the resin flow path portion <NUM> is shown by a dotted line. A portion indicated by reference numeral 5a out of the resin flow path portion <NUM> and the plurality of hole portions <NUM> shown in <FIG> corresponds to a portion formed in the die member 5a, and a portion indicated by reference numeral 5b corresponds to a portion formed in the die member 5b. <FIG> substantially corresponds to a sectional view taken at a position of line B1-B1 shown in <FIG>, <FIG> substantially corresponds to a sectional view taken at a position of line B2-B2 shown in <FIG>, and <FIG> substantially corresponds to a sectional view taken at a position of line B3-B3 shown in <FIG>. Incidentally, <FIG> corresponds to the sectional view taken at the position of line A1-A1 in <FIG>, but also corresponds to the sectional view taken at the position of line C1-C1 in <FIG>. Further, although <FIG> corresponds to the sectional view taken at the position of line A2-A2 in <FIG>, but also corresponds to the sectional view taken at the position of line C2-C2 in <FIG>. Furthermore, since <FIG> is a schematic view, the number of hole portions <NUM> in <FIG> does not match with the number of hole portions <NUM> in each of <FIG> and <FIG>, but actually match with it. The number of hole portions <NUM> formed in the die <NUM> can be, for example, about <NUM> to <NUM>.

The resin flow path portion <NUM> has an inflow port (opening) <NUM> in which the molten resin from the cylinder <NUM> flows, a resin introduction portion <NUM> coupled to the inflow port <NUM>, and a slit portion <NUM> located on a downstream side of the resin introduction portion <NUM> and coupled to the resin introduction portion <NUM>. The plurality of hole portions <NUM> are coupled with a downstream-side end portion of the slit portion <NUM>. A diameter of each hole portion <NUM> is considerably smaller than a width (dimension in the X direction) of the slit portion <NUM>. Further, a diameter of each hole portion <NUM> is smaller than a thickness (dimension in the Z direction) of the slit portion <NUM>.

A shape of the inflow port <NUM> is, for example, rectangular, circular, elliptical or oval. A width of the inflow port <NUM> corresponds to dimension of the inflow port <NUM> in the X direction. The inflow port <NUM> is an opening formed by the resin introduction portion <NUM> reaching a surface (a surface on a side connected to the cylinder <NUM>) of the die member 5b. That is, an upstream-side end face of the resin introduction portion <NUM> is the inflow port <NUM>.

The slit portion <NUM> has a slit-like (plate-like) shape having a plane (main surface) substantially parallel to the X direction and the Y direction. A planar shape of the slit portion <NUM> is substantially rectangular. Each side of a rectangle forming the planar shape of the slit portion <NUM> is parallel to either the X direction or the Y direction. In cases of <FIG>, a long side of the slit portion <NUM> is substantially parallel to the X direction, a short side of the slit portion <NUM> is substantially parallel to the Y direction, and a thickness direction of the slit portion <NUM> is the Z direction. The thickness (dimension in the Z direction) of the slit portion <NUM> is smaller than the width (dimension in the X direction) of the slit portion <NUM> and smaller than a length (dimension in the Y direction) of the slit portion <NUM>.

The width (dimension in the X direction) of the slit portion <NUM> is substantially constant (uniform), and the length (dimension in the Y direction) of the slit portion <NUM> is substantially constant (uniform). Further, although the thickness (dimension in the Z direction) of the slit portion <NUM> is substantially constant (uniform), a part of the plate member <NUM> projects from the slit portion <NUM>. Consequently, in the slit portion <NUM>, a region where the plate member <NUM> protrudes becomes smaller only the protrusion amount (protrusion distance) t1 of the plate member <NUM> in an effective thickness of the slit portion <NUM> as compared with a region other than the region where the plate member <NUM> protrudes. The thickness (dimension in the Y direction) of the plate member <NUM> is smaller than the length (dimension in the Y direction) of the slit portion <NUM>.

Here, the protrusion amount t1 of the plate member <NUM> corresponds to a protrusion amount (protrusion distance) of the plate member <NUM> with respect to the slit portion <NUM>, and is shown in <FIG>, <FIG>, <FIG> and <FIG> described later. A difference (distance in the Z direction) in height position between an upper surface 33a (upper surface of the slit portion <NUM> of the slit portion <NUM> that does not overlap with the plate member <NUM> in a plan view) and a tip surface 11a of the plate member <NUM> corresponds to the protrusion amount t1 of the plate member <NUM>.

A width (dimension in the X direction) of an upstream-side end surface of the resin introduction portion <NUM> coincides with a width (dimension in the X direction) of the inflow port <NUM>. Further, a width (dimension in the X direction) of a downstream-side end portion of the resin introduction portion <NUM> coincides with a width (dimension in the X direction) of an upstream-side end portion of the slit portion <NUM>. The width (dimension in the X direction) of the slit portion <NUM> is larger than the width (dimension in the X direction) of the inflow port <NUM>. Consequently, in the resin introduction portion <NUM>, the width (dimension in the X direction) of the resin introduction portion <NUM> gradually increases from an upstream side toward a downstream side. Therefore, the planar shape of the resin introduction portion <NUM> is substantially trapezoidal. Furthermore, the thickness (dimension in the Z direction) of the resin introduction portion <NUM> gradually decreases from the upstream side toward the downstream side. The molten resin extruded from the cylinder <NUM> flows from the inflow port <NUM> of the die member 5b, passes through the resin introduction portion <NUM> and the slit portion <NUM> in order, flows into the plurality of hole portions <NUM>, and is discharged as the strand <NUM> from the plurality of hole portions <NUM> to the outside of the die <NUM>.

The resin introduction portion <NUM> and the slit portion <NUM> are adjacent to each other in the Y direction and, therefore, the resin introduction portion <NUM> communicates with (spatially connects with) the slit portion <NUM>. Consequently, the downstream-side end portion of the resin introduction portion <NUM> and the upstream-side end portion of the slit portion <NUM> are adjacent to each other in the Y direction, and form a boundary between the resin introduction portion <NUM> and the slit portion <NUM>. Therefore, the width (dimension in the X direction) of the slit portion <NUM> is the same as a width (dimension in the X direction) at the downstream-side end portion of the resin introduction portion <NUM>, and the thickness (dimension in the Z direction) of the slit portion <NUM> is the same as a thickness (dimension in the Z direction) at the downstream-side end portion of the resin introduction portion <NUM>. The plurality of hole portions <NUM> are adjacent to the slit portion <NUM> in the Y direction and, therefore, the slit portion <NUM> communicates with (spatially connects with) the plurality of hole portions <NUM>. Further, at the boundary between the resin introduction portion <NUM> and the slit portion <NUM>, the thickness (dimension in the Z direction) of the resin introduction portion <NUM> and the thickness (dimension in the Z direction) of the slit portion <NUM> coincide with each other, but except for the boundary between the resin introduction portion <NUM> and the slit portion <NUM>, the thickness (dimension in the Z direction) of the slit portion <NUM> is thinner (smaller) than the thickness (dimension in the Z direction) of the resin introduction portion <NUM>.

The plate member <NUM> is arranged at a position overlapping with the slit portion <NUM> in a plan view. Incidentally, the plan view corresponds to a case of being viewed in a plane parallel to the X direction and the Y direction.

The plate member <NUM> is a plate-shaped member having a plane substantially parallel to the X and Z directions, and the thickness (dimension in the Y direction) of the plate member <NUM> is smaller than the length (dimension in the Y direction) of the slit portion <NUM>. Incidentally, a thickness direction of the plate member <NUM> is the Y direction. In a plan view, the plate member <NUM> is arranged on a downstream side of the upstream-side end portion (that is, the boundary between the resin introduction portion <NUM> and the slit portion <NUM>) of the slit portion <NUM> and on an upstream side of the downstream-side end portion of the slit portion <NUM>. That is, in a plan view, the plate member <NUM> is arranged in an intermediate region (region away from both end portions) of the slit portion <NUM> in the Y direction. Namely, the plate member <NUM> protrudes in the middle (in the middle in the Y direction) of the slit portion <NUM>. Incidentally, since the plate member <NUM> is inserted into the groove portion <NUM>, a position of the groove portion <NUM> coincides with the position of the plate member <NUM> in a plan view.

The protrusion amount t1 of the plate member <NUM> with respect to the slit portion <NUM> is not uniform in a width direction (X direction). Specifically, the protrusion amount t1 of the plate member <NUM> with respect to the slit portion <NUM> is the largest at a center of the slit portion <NUM> in the width direction (X direction), and gradually becomes smaller toward both ends from the center of the slit portion <NUM> in the width direction (X direction). Consequently, in the width direction (X direction) of the slit portion <NUM>, the protrusion amount t1 of the plate member <NUM> at the center of the slit portion <NUM> is larger than the protrusion amount t1 of the plate member <NUM> at the both ends of the slit portion <NUM>.

The plate member <NUM> is movable in the up-and-down direction (Z direction) so as to project from the slit portion <NUM>, but both end portions of the plate member <NUM> in the X direction move in the up-and-down direction (Z direction) so as to contact with an inner wall of the slit portion <NUM>. That is, the both end portions of the plate member <NUM> in the X direction do not move in the up-and-down direction (Z direction) in a state of being separated from the inner wall (inside wall) of the slit portion <NUM>, but moves in the up-and-down direction (Z direction) so as to contact with the inner wall (inside wall) of the slit portion <NUM>. Consequently, the width (dimension in the X direction) of the plate member <NUM> is the same as the width (dimension in the X direction) of the slit portion <NUM> or is larger than the width (dimension in the X direction) of the slit portion <NUM>. Thus, the plate member <NUM> does not protrude only from a part of the width of the slit portion <NUM>, but protrudes over the entire width of the slit portion <NUM>. That is, the plate member <NUM> protrudes not only in the vicinity of a central portion in the width direction (X direction) of the slit portion <NUM> but also in the vicinity of the both end portions in the width direction (X direction) of the slit portion <NUM>. Therefore, the plate member <NUM> is in a state of protruding over the entire width of the slit portion <NUM> in the middle (in the middle in the Y direction) of the slit portion <NUM>. For this reason, in the cross section shown in <FIG> and <FIG> described later, t1 > <NUM> is met from the center toward the both ends in the width direction (X direction) of the slit portion <NUM>. That is, in the cross section shown in <FIG> and <FIG> described later, t1 > <NUM> is met not only at the center of the slit portion <NUM> in the width direction (X direction) but also at the both ends.

Further, the extending direction of each of the plurality of hole portions <NUM> provided in the die member 5a is inclined downward from the Y direction. That is, each hole portion <NUM> extends diagonally downward. Consequently, the molten resin is discharged diagonally downward from the plurality of hole portions <NUM>, so that the strand <NUM> can be easily guided to the cooling tank <NUM>.

Further, in the present embodiment, a length (dimension of the hole portion <NUM> in the extending direction, nozzle length) L1 of each of the plurality of hole portions <NUM> provided in the die member 5a is greater than a thickness (dimension in the Z direction) t3 of the slit portion <NUM> (i.e., L1 > t3). Incidentally, the length L1 is shown in <FIG>, and the thickness t3 is shown in <FIG>. The length L1 of each hole portion <NUM> may be set to the thickness t3 or less (L1 ≤ t3) of the slit portion <NUM>, but uniformity of the flow velocity distribution of the molten resin discharged from the plurality of hole portions <NUM> is easily increased when pressure of the molten resin at the tip of the hole portion <NUM> is high to some extent. From this viewpoint, the length L1 of each hole portion <NUM> is preferably lengthened to some extent and, in the present embodiment, it is more preferable that the length L1 is larger than the thickness t3 of the slit portion <NUM> (L1 > t3).

Further, in the extruder <NUM> of the present embodiment, the plate member <NUM> inserted in the groove portion <NUM> of the die member 5b is movable in the up-and-down direction. <FIG> is a sectional view of a main part of the die <NUM>, and substantially corresponds to the sectional view taken at the position of line B2-B2 shown in <FIG> similarly to <FIG> described above. However, <FIG> corresponds to a case where the plate member <NUM> is moved downward to lower the height position of the plate member <NUM> as compared with the case of <FIG>. Consequently, the protrusion amount t1 of the plate member <NUM> with respect to the slit portion <NUM> is larger in the case of <FIG> than in the case of <FIG>.

Although its details will be described later, the flow velocity distribution of the molten resin that flows through the resin flow path portion <NUM> can be controlled by adjusting the protrusion amount t1 of the plate member <NUM> in the resin flow path portion <NUM>. For example, when viscosity of the molten resin is low, as shown in <FIG>, the height position of the plate member <NUM> is increased to reduce the protrusion amount t1 of the plate member <NUM> in the resin flow path portion <NUM>. Meanwhile, when the viscosity of the molten resin is high, as shown in <FIG>, the height position of the plate member <NUM> is lowered to increase the protrusion amount t1 of the plate member <NUM> in the resin flow path portion <NUM>. Consequently, the flow velocity of the molten resin discharged from the plurality of hole portions <NUM> can be made uniform in both the case where the viscosity of the molten resin is low and the case where the viscosity of the molten resin is high.

<FIG> is a plan view showing a resin flow path portion <NUM> and a plurality of hole portions <NUM> formed in a die of an extruder of a first study example that has been examined by the present inventor(s), and shows a region corresponding to each of <FIG>. The resin flow path portion <NUM> shown in <FIG> corresponds to the above-mentioned resin flow path portion <NUM>, and the hole portions <NUM> shown in <FIG> correspond to the above-mentioned hole portions <NUM>. The resin flow path portion <NUM> is configured by a resin introduction portion <NUM> corresponding to the above-mentioned resin introduction portion <NUM> and a slit portion <NUM> corresponding to the above-mentioned slit portion <NUM>.

The first study example is different from the present embodiment in that it has no member corresponding to the plate member <NUM>. Consequently, in the first study example, a member corresponding to the above-mentioned groove portion <NUM> is not formed in the die.

Also in a case of the first study example, the molten resin extruded from the above-mentioned cylinder <NUM> flows from an inflow port <NUM> of the die member, passes through the resin introduction portion <NUM> and the slit portion <NUM> in order, flows into the plurality of hole portions <NUM>, and is discharged as a strand from the plurality of hole portions <NUM> to the outside of the die.

In <FIG>, a flow of the molten resin in the resin flow path portion <NUM> is schematically shown by arrows. As can be seen from <FIG>, the molten resin that has flowed from the cylinder <NUM> into the inflow port <NUM> of the die member flows in the Y direction while spreading in the X direction (on both end portion sides in the X direction) in the resin introduction portion <NUM>. That is, the resin introduction portion <NUM> has a flow that spreads in the X direction and a flow that moves in the Y direction. Further, in the slit portion <NUM>, the molten resin flows in the substantially Y direction. Consequently, in the slit portion <NUM>, flow path resistance is larger in the vicinity of both end portions in the X direction than in the vicinity of the center in the X direction. Therefore, in the slit portion <NUM>, the flow velocity of the molten resin is smaller in the vicinity of the both end portions in the X direction than in the vicinity of the center in the X direction, which may make the flow velocity distribution of the molten resin (strand) discharged from the plurality of hole portions <NUM> non-uniform. Specifically, among the plurality of hole portions <NUM> arranged in the X direction, the flow velocity of the molten resin (strand) discharged from the hole portions <NUM> in the vicinity of the both end portions in the X direction becomes smaller than the flow velocity of the molten resin discharged from the hole portions <NUM> in the vicinity of the center in the X direction. This may bring a decrease in quality of a resin product (here, resin pellet) which is manufactured by using the molten resin extruded from the die, so that improvement of such a situation is desired.

The die <NUM> attached to the cylinder <NUM> of the extruder <NUM> is an extrusion die. The die <NUM> includes an inflow port <NUM> which is an opening for supplying a molten resin, a plurality of hole portions (die hole portions) <NUM> for discharging a strand (s) made of the molten resin, and a resin flow path portion <NUM> extending in a flow path direction (here, the Y direction) leading to the plurality of hole portions <NUM> from the inflow port <NUM>.

One of main features of the present embodiment is that a plate member (moving plate) <NUM> movable in the up-and-down direction (Z direction) so as to project toward the resin flow path portion <NUM> (more specifically, the slit portion <NUM>) is provided on the die <NUM>. The plate member <NUM> is arranged along a direction (here, X direction) orthogonal to each of the flow path direction (Y direction), which leads to the plurality of hole portions <NUM> from the inflow port <NUM> and the vertical direction (Z direction). Both end portions of the plate member <NUM> in the X direction move in the up-and-down direction (Z direction) so as to contact with an inner wall of the resin flow path portion <NUM> (more specifically, the slit portion <NUM>). A protrusion amount t1 of the plate member <NUM> with respect to the resin flow path portion <NUM> (more specifically, the slit portion <NUM>) becomes small from a central portion (central portion of the plate member <NUM> in the X direction) in the X direction toward the both end portions (both end portions of the plate member in the X direction).

Incidentally, the both end portions of the plate member <NUM> in the X direction move in the up-and-down direction (Z direction) so as to contact with the inner wall of the resin flow path portion <NUM> (more specifically, the slit portion <NUM>), so that to reflect such movement, the plate member <NUM> protrudes over the entire width of the resin flow path portion <NUM> (more specifically, the slit portion <NUM>) in the middle of the resin flow path portion <NUM> (more specifically, the slit portion <NUM>).

<FIG> is a graph showing a flow velocity distribution of the molten resin. (a) of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B1-B1 in <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B3-B3 in <FIG>, and <FIG> of <FIG> shows a flow velocity distribution of the molten resin immediately after being discharged from the plurality of hole portions <NUM>. In the graphs of (a), (b), and (c) of <FIG>, a vertical axis corresponds to a flow velocity of the molten resin and is shown in an arbitrary unit. Further, in the graphs of (a), (b), and (c) of <FIG>, a horizontal axis corresponds to a position in the X direction. In (a) and (b) of <FIG>, a center of the horizontal axis corresponds to the center of the slit portion <NUM> in the X direction, and both end portions of the horizontal axis correspond to the both end portions of the slit portion <NUM> in the X direction. Meanwhile, in (c) of <FIG>, a center of the horizontal axis corresponds to a flow velocity of the molten resin discharged from the central hole portion <NUM> among the plurality of hole portions <NUM> arranged in the X direction, and both end portions in the horizontal axis correspond to a flow velocity of the molten resin discharged from the hole portions <NUM> at the both end portions among the plurality of hole portions <NUM> arranged in the X direction.

The molten resin extruded from the cylinder <NUM> of the extruder <NUM> flows from the inflow port <NUM> of the die <NUM>, passes through the resin flow path portion <NUM> (more specifically, passing through the resin introduction portion <NUM> and the slit portion <NUM> in order), flows into the plurality of hole portions <NUM>, and is discharged from the plurality of hole portions <NUM> to the outside of the die <NUM>. In <FIG> mentioned above, the flow of the molten resin in the resin flow path portion <NUM> is schematically shown by arrows. As can be seen from <FIG>, the molten resin flowing from the cylinder <NUM> to the inflow port <NUM> of the die <NUM> flows in the Y direction while spreading in the X direction (on both end portion sides in the X direction) in the resin introduction portion <NUM>. That is, the resin introduction portion <NUM> has is a flow that spreads in the X direction and a flow that moves in the Y direction. Further, in the slit portion <NUM>, the molten resin substantially flows in the Y direction. Consequently, the flow path resistance leading to the slit portion <NUM> from the inflow port <NUM> is larger in the vicinity of the both end portions of the slit portion <NUM> in the X direction than in the vicinity of the center of the slit portion <NUM> in the X direction. Therefore, as shown in (a) of <FIG>, the flow velocity of the molten resin immediately after flowing from the resin introduction portion <NUM> into the slit portion <NUM> tends to become smaller in the vicinity of the both end portions in the X direction than in the vicinity of the center in the X direction. Consequently, the flow velocity distribution when the molten resin flows from the resin introduction portion <NUM> into the slit portion <NUM> becomes larger at the center in the width direction (here, the X direction) of the slit portion <NUM> as shown in (a) of <FIG>, and may have such a distribution as to gradually decreases from the center toward the both ends in the width direction (here, the X direction) of the slit portion <NUM>.

In the present embodiment, the plate member <NUM> projects over the entire width of the slit portion <NUM> in the middle of the slit portion <NUM>. A protruding portion of the plate member <NUM> with respect to the slit portion <NUM> acts to suppress the flow of the molten resin in the slit portion <NUM>. That is, in the slit portion <NUM>, the effective thickness of the slit portion <NUM> becomes smaller only the protrusion amount t1 of the plate member <NUM> in a region where the plate member <NUM> protrudes than in a region other than the region where the plate member <NUM> protrudes, so that the molten resin does not easily flow in the region where the plate member <NUM> protrudes. Then, in the present embodiment, the protrusion amount t1 of the plate member <NUM> with respect to the slit portion <NUM> becomes large at the center in the width direction (here, the X direction) of the slit portion <NUM>, and gradually becomes smaller from the center toward the both ends of the slit portion <NUM> in the width direction (here, the X direction). The protruding portion of the plate member <NUM> with respect to the slit portion <NUM> acts to suppress (inhibit) the flow (flow velocity) of the molten resin in the slit portion <NUM>, but the action increases as the protrusion amount t1 of the plate member <NUM> increases and decreases as the protrusion amount t1 of the plate member <NUM> decreases. Consequently, the protrusion amount t1 of the plate member <NUM> with respect to the slit portion <NUM> is large in the vicinity of the center of the slit portion <NUM> in the width direction (X direction), so that to reflect such a situation, the action in which the flow (flow velocity) of the molten resin is suppressed by the plate member <NUM> is the greatest. Then, the protrusion amount t1 of the plate member <NUM> gradually decreases from the center of the slit portion <NUM> in the width direction (X direction) toward the both end sides, so that to reflect such a situation, the action in which the flow (flow velocity) of the molten resin is suppressed by the plate member <NUM> gradually decreases (becomes small), too. That is, in the slit portion <NUM>, considering the flow path resistance when the molten resin passes below the protruding portion of the plate member <NUM>, the flow path resistance is the largest in the vicinity of the center of the slit portion <NUM> in the width direction (X direction), and the flow path resistance gradually decreases from the center of the slit portion <NUM> in the width direction (X direction) toward the both end sides.

Consequently, the protruding portion of the plate member <NUM> with respect to the slit portion <NUM> can act to alleviate (improve) the non-uniformity of the flow velocity distribution of the molten resin as shown in (a) of <FIG>. That is, the protruding portion of the plate member <NUM> with respect to the slit portion <NUM> can act to make the flow velocity distribution of the molten resin uniform. For this reason, after the molten resin passes below the protruding portion of the plate member <NUM>, the flow velocity distribution of the molten resin becomes a distribution as shown in (b) of <FIG>, and becomes almost uniform regardless of the position in the X direction. This makes it possible to make the flow velocity when the molten resin flows from the slit portion <NUM> into the plurality of hole portions <NUM> substantially uniform regardless of the position in the X direction. Therefore, the plurality of hole portions <NUM> mutually have substantially the same flow velocity. Consequently, as shown in (c) of <FIG>, the flow velocity distribution of the molten resin (strand <NUM>) discharged from the plurality of hole portions <NUM> can be made uniform. Specifically, in the plurality of hole portions <NUM> arranged in the X direction, the respective flow velocities of the molten resin discharged from the respective hole portions <NUM> can be made substantially the same. This makes it possible to improve the quality of the resin product (here, pellet <NUM>) manufactured by using the resin extruded from the die <NUM>. In addition, dimensional uniformity of the manufactured pellets <NUM> can be improved. Further, the resin product (here, pellet <NUM>) can be more accurately manufactured by using the resin extruded from the die <NUM>. Furthermore, substantially the same flow velocity makes it easier to manage a manufacturing process.

Further, if a type and a ratio of the resin material and the filler to be kneaded in the cylinder <NUM> of the extruder <NUM> are changed, the viscosity of the molten resin supplied from the cylinder <NUM> to the resin flow path portion <NUM> of the die <NUM> can be changed. Furthermore, the viscosity of the molten resin supplied from the cylinder <NUM> to the resin flow path portion <NUM> of the die <NUM> can be changed by changing conditions and the like for kneading the resin in the cylinder <NUM>.

<FIG> is a graph showing the flow velocity distribution of the molten resin. Similar to (a) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B1-B1 in <FIG>. Further, similarly to (a) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B3-B3 of <FIG>. Furthermore, similarly to (c) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin immediately after being discharged from the plurality of hole portions <NUM>. <FIG> corresponds to the flow velocity distribution when the viscosity of the molten resin is higher than that in the case of <FIG>.

Also in both of a case where the viscosity of the molten resin is low ((a) of <FIG>) and a case where the viscosity of the molten resin is high ((a) in <FIG>), the flow viscosity distribution when the molten resin flows from the resin introduction portion <NUM> into the slit portion <NUM> may have such a distribution as to become large at the center of the slit portion <NUM> in the width direction (X direction) and to gradually decrease from the center of the slit portion <NUM> in the width direction (X direction) toward the both ends. However, the non-uniformity of the flow velocity distribution when the molten resin flows from the resin introduction portion <NUM> to the slit portion <NUM> has a tendency to become larger in the high viscosity of the molten resin ((a) of <FIG>) than in the low viscosity of the molten resin ((a) of <FIG>). That is, a difference between the flow velocity at the central portion of the slit portion <NUM> in the width direction (X direction) and the flow velocity at the both end portions of the slit portion <NUM> in the width direction (X direction) is larger when the viscosity of the molten resin is high ((a) of <FIG>) than when the viscosity of the molten resin is low ((a) of <FIG>). This is because a difference in flow velocity due to a difference in flow path resistance is larger when the viscosity of the molten resin is high than when the viscosity of the molten resin is low.

In the case of <FIG> (when the viscosity of the molten resin is low), the height position of the plate member <NUM> is set as shown in <FIG>. By doing so, after the molten resin has passed below the protruding portion of the plate member <NUM>, the flow velocity of the molten resin can be made substantially uniform regardless of the position in the X direction. However, in the case of <FIG> (when the viscosity of the molten resin is high), if the height position of the plate member <NUM> is set as shown in <FIG> and even if the protruding portion of the plate member <NUM> is present, the non-uniformity of the flow velocity distribution of the molten resin may not be sufficiently alleviated and may remain to some extent even after the molten resin has passed below the protruding portion of the plate member <NUM>.

In contrast thereto, in the present embodiment, the plate member <NUM> is movable in the up-and-down direction (Z direction). Consequently, in the case of <FIG> (when the viscosity of the molten resin is high), the height position of the plate member <NUM> is lowered as compared with the case of <FIG> (when the viscosity of the molten resin is low). That is, in the case of <FIG> (when the viscosity of the molten resin is low), the height position of the plate member <NUM> is set as shown in <FIG>, whereas in the case of <FIG> (when the viscosity of the molten resin is high), the height position of the plate member <NUM> is set as shown in <FIG>. The height position of the plate member <NUM> is lower in the case of <FIG> (when the viscosity of the molten resin is high) than in the case of <FIG> (when the viscosity of the molten resin is low) and, therefore, the protrusion amount t1 of the plate member <NUM> becomes large.

Although the height position of the plate member <NUM> in the case of <FIG> is different from that of <FIG>, the plate member <NUM> itself is the same. Consequently, also in both the case of <FIG> and the case of <FIG>, the protrusion amount t1 of the plate member <NUM> becomes large at the center of the slit portion <NUM> in the width direction (X direction), and gradually becomes smaller from the center of the slit portion <NUM> in the width direction (X direction) toward the both ends. Therefore, in both the case of <FIG> and the case of <FIG>, an effective thickness t2 of the slit portion <NUM> below the protruding portion of the plate member <NUM> becomes smaller at the center of the slit portion <NUM> in the width direction (the X direction) and gradually becomes larger from the center of the slit potion <NUM> in the width direction (the X direction) toward the both ends.

However, the case of <FIG> is lower in the height position of the plate member <NUM> than the case of <FIG>, so that to reflect such a situation, the protrusion amount t1 of the plate member <NUM> is larger in the case of <FIG> than in the case of <FIG>. By reflecting this, the effective thickness t2 of the slit portion <NUM> below the protruding portion of the plate member <NUM> becomes smaller in the case of <FIG> than in the case of <FIG>.

Here, it is assumed that in the case of <FIG>, the effective thickness t2 at the center of the slit portion <NUM> in the width direction (X direction) is referred to as a thickness t2a, and the effective thickness t2 at the both end portions of the slit portions <NUM> in the width direction (X direction) is referred to as a thickness t2b. Further, it is assumed that in the case of <FIG>, the effective thickness t2 at the center of the slit portion <NUM> in the width direction (X direction) is referred to as a thickness t2c, and the effective thickness at the both end portions of the slit portions <NUM> in the width direction (X direction) is referred to as a thickness t2d.

A difference (t2d - t2c) between the thickness t2c at the center and the thickness t2d at the both end portions in the case of <FIG> is the same as a difference (t2b - t2a) between the thickness t2a at the center and the thickness t2b at the both end portions in the case of <FIG>. That is, t2b - t2a = t2d - t2c is met. However, a ratio (t2d / t2c) of the thickness t2d at the both end portions to the thickness t2c at the center in the case of <FIG> becomes larger than a ratio (t2b / t2a) of the thickness t2b at the both end portions to the thickness t2a at the center in the case of <FIG>. That is, t2b / t2a < t2d / t2c is met. Consequently, the protruding portion of the plate member <NUM> acts to suppress the flow (flow velocity) of the molten resin in the slit portion <NUM>, but a difference between flow velocity suppressing action at the center in the width direction (X direction) and flow velocity suppressing action on the both end portion sides in the width direction (the X direction) becomes larger in the case of <FIG> than in the case of <FIG>. The difference between the flow velocity suppressing action at the center in the width direction (X direction) and the flow velocity suppressing action at the both end portion sides in the width direction (X direction) has a tendency to become larger as the ratio (t2b / t2a or t2d / t2c) of the effective thickness t2 on the both end portions in the width direction (X direction) to the effective thickness t2 at the center in the width direction (X direction) becomes larger.

Thus, when the viscosity of the molten resin is high, as shown in <FIG>, the height position of the plate member <NUM> is lowered to increase the protrusion amount t1 of the plate member <NUM>, which brings an increase in a value of t2d / t2c to increase the difference between the flow velocity suppressing action at the center in the width direction (X direction) and the flow velocity suppressing action on the both end portion sides in the width direction (X direction). Consequently, even when the viscosity of the molten resin is high, the flow velocity distribution of the molten resin after the molten resin has passed below the protruding portion of the plate member <NUM> becomes the distribution as shown in (b) of <FIG> and becomes almost uniform regardless of the position in the X direction. Thus, the flow velocity when the molten resin flows from the slit portion <NUM> into the plurality of hole portions <NUM> can be made substantially uniform regardless of the position in the X direction. Therefore, the respective flow velocities of the molten resin discharged from the plurality of hole portions <NUM> can be made substantially the same. For this reason, as shown in (c) of <FIG>, the flow velocity distribution of the molten resin (strand <NUM>) discharged from the plurality of hole portions <NUM> can be made uniform. Specifically, in the plurality of hole portions <NUM> arranged in the X direction, the respective flow velocities of the molten resin discharged from the respective hole portions <NUM> can be made substantially the same, too.

In this way, since the present embodiment is configured to be capable of moving the plate member <NUM> in the up-and-down direction (Z direction), the height position of the plate member <NUM> can be adjusted according to characteristics (specifically, viscosity) of the molten resin supplied from the cylinder <NUM> to the resin flow path portion <NUM> and, thereby, the protrusion amount t1 of the plate member <NUM> can be changed (controlled). Consequently, the above change (control) can be handled by changing the height position of the plate member <NUM> even if the viscosity of the molten resin supplied from the cylinder <NUM> to the resin flow path portion <NUM> of the die <NUM> is changed by changing the type and ratio of the resin material and the filler to be kneaded in the cylinder <NUM> of the extruder <NUM> or by changing the conditions or the like for kneading the resin in the cylinder <NUM>. This makes it possible to make the flow velocity distribution of the molten resin (strand <NUM>) discharged from the plurality of hole portions <NUM> of the die <NUM> uniform even if the characteristics (viscosity) of the molten resin change. That is, in the plurality of hole portions <NUM> of the die <NUM>, the respective flow velocities of the molten resin discharged from the respective hole portions <NUM> can be made substantially the same, too. Thus, even if the characteristics (viscosity) of the molten resin change, the resin product (here, pellet <NUM>) can be accurately manufactured by using the resin extruded from the die <NUM> and the quality of the manufactured resin product can be improved. In addition, the dimensional uniformity of the manufactured pellets <NUM> can be improved. Furthermore, the present embodiment makes it easier to manage the manufacturing process.

Next, a case where plate members (<NUM>, <NUM>, <NUM>) of study examples that have been examined by the present inventor is used instead of the plate member <NUM> of the present embodiment will be described below.

<FIG> is a sectional view of a die showing a case where a plate member <NUM> of a second study example that has been examined by the present inventor is used instead of the plate member <NUM> of the present embodiment, is a sectional view of a die, and shows a cross-section corresponding to that of <FIG> mentioned above.

In a case of <FIG>, a protrusion amount t201 of the plate member <NUM> with respect to the slit portion <NUM> is uniform in the width direction (X direction) of the slit portion <NUM>. Consequently, an effective thickness of the slit portion <NUM> is constant below a protruding portion of the plate member <NUM> regardless of positions in the X direction. For this reason, in the case of <FIG>, even if the plate member <NUM> protrudes toward the slit portion <NUM>, the action of making the flow velocity distribution of the molten resin uniform cannot be obtained.

<FIG> is a sectional view of a die showing a case of using a plate member <NUM> of a third study example examined by the present inventor instead of the plate member <NUM> of the present embodiment, and shows a cross-section corresponding to that of <FIG> mentioned above. <FIG> is a graph showing a flow velocity distribution of a molten resin when the plate member <NUM> of the third study example is used. Similar to (a) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B1-B1 in <FIG> mentioned above. Further, similarly to (b) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B3-B3 in <FIG> mentioned above. Furthermore, similarly to (c) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin immediately after being discharged from the plurality of hole portions <NUM>.

In a case of <FIG>, a protrusion amount t301 of the plate member <NUM> with respect to the slit portion <NUM> is uniform in the width direction (X direction) of the slit portion <NUM>. Consequently, an effective thickness of the slit portion <NUM> below a protruding portion of the plate member <NUM> becomes constant regardless of the position in the X direction. Thus, below the protruding portion of the plate member <NUM>, flow velocity resistance becomes constant regardless of the position in the X direction, so that even if the molten resin passes below the protruding portion of the plate member <NUM>, as shown in (b) of <FIG>, the flow velocity distribution is not uniformized and the non-uniformity of the flow velocity distribution leads to remaining.

Further, a width (dimension in the X direction) of the plate member <NUM> of the third study example is smaller than the width (dimension in the X direction) of the slit portion <NUM>. Consequently, the plate member <NUM> protrudes not toward the entire width of the slit portion <NUM> but toward only a part of the width of the slit portion. Since the action of suppressing the flow of the molten resin by the plate member <NUM> occurs only in a region where the protruding portion of the plate member <NUM> exists, the flow velocity distribution of the molten resin on the downstream side of the plate member <NUM> becomes, as shown in (b) of <FIG>, a distribution that has steps at positions corresponding to both end portions (both end portions in the X direction) of the plate member <NUM>. Thus, when the plate member <NUM> is used, the flow velocity distribution of the molten resin discharged from the plurality of hole portions <NUM> may also become non-uniform as shown in (c) of <FIG>.

<FIG> is a sectional view of a die showing a case where a plate member <NUM> of a fourth study example examined by the present inventor is used instead of the plate member <NUM> of the present embodiment, and shows a cross-section corresponding to that of <FIG> mentioned above. <FIG> is a graph showing a flow velocity distribution of the molten resin where the plate member <NUM> of the fourth study example is used. Similar to (a) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B1-B1 in <FIG> mentioned above. Furthermore, similarly to (b) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin flowing through the slit portion <NUM> at the position of line B3-B3 in <FIG> mentioned above. Moreover, similarly to (C) of <FIG>, <FIG> of <FIG> shows a flow velocity distribution of the molten resin immediately after being discharged from the plurality of hole portions <NUM>.

In a case of <FIG>, a protrusion amount t401 of the plate member <NUM> with respect to the slit portion <NUM> increases at a center in the width direction (X direction), and gradually decreases from the center toward both ends in the width direction (X direction). Consequently, when the molten result passes below a protruding portion of the plate member <NUM>, a flow velocity distribution of the molten resin on a downstream side of the plate member <NUM> acts to be uniformized.

However, a width (dimension in the X direction) of the plate member <NUM> of the fourth study example is smaller than the width (dimension in the X direction) of the slit portion <NUM>, and the plate member <NUM> protrudes not toward the entire width of the slit portion <NUM> but toward only a part of the width of the slit portion. Since the action of suppressing the flow of the molten resin by the plate member <NUM> occurs only in the region where the protruding portion of the plate member <NUM> exists, the flow velocity distribution of the molten resin on the downstream side of the plate member <NUM> becomes, as shown in (b) of <FIG>, a distribution that has steps at positions corresponding to both end portions (both end portions in the X direction) of the plate member <NUM>. Thus, when the plate member <NUM> is used, the flow velocity distribution of the molten resin discharged from the plurality of hole portions <NUM> may also become non-uniform as shown in (c) of <FIG>.

Therefore, it can be seen that two matters are important in order to make the flow velocity distribution of the molten resin on the downstream side of the plate member uniform. That is, the first matter is that, like the plate member <NUM> of the present embodiment, the protrusion amount t1 of the plate member <NUM> becomes large at the center in the width direction (X direction) and gradually becomes smaller from the center toward the both ends. The second matter is that the plate member <NUM> protrudes toward the entire width of the resin flow path portion <NUM> (more specifically, the slit portion <NUM>) in the middle of the resin flow path portion <NUM> (more specifically, the slit portion <NUM>). Using the plate member <NUM> of the present embodiment that satisfies these two matters makes it possible to make the flow velocity distribution of the molten resin on the downstream side of the plate member <NUM> uniform. By allowing the plate member <NUM> to move in the up-and-down direction, the height position of the plate member <NUM> is adjustable according to the characteristics (viscosity) of the molten resin, so that even if the characteristics (viscosity) of the molten resin have changed, the flow velocity distribution of the molten resin discharged from the plurality of hole portions <NUM> of the die <NUM> can be made uniform.

<FIG> is a sectional view of a main part of the plate member <NUM> used in the present embodiment, <FIG> is a sectional view of a main part showing a first modification example of the plate member <NUM>, and <FIG> is a sectional view of a main part showing a second modification example of the plate member <NUM>. <FIG> each show a sectional view of a tip portion of the plate member <NUM>, which corresponds to a cross-section substantially perpendicular to a thickness direction (Y direction) of the plate member <NUM>. The tip portion of the plate member <NUM> each shown in <FIG> projects toward the resin flow path portion <NUM> (more specifically, the slit portion <NUM>).

The plate member <NUM> projects toward the slit portion <NUM> so that a tip surface 11a of the plate member <NUM> becomes lower than an upper surface 33a of the slit portion <NUM>. The tip surface 11a of the plate member <NUM> has a shape in which a height position is low at the center in the width direction (X direction) and the height position is gradually increased from the center toward the both ends in the width direction (X direction). This is common to a case of <FIG>, a case of <FIG>, and a case of <FIG>. Since the plate member <NUM> has such a shape, as described above, the protrusion amount t1 of the plate member <NUM> can be accurately realized so as to becomes large at the center in the width direction (X direction) and gradually decrease from the center toward the both ends in the width direction (X direction).

In the case of <FIG>, in a sectional view substantially perpendicular to the thickness direction (Y direction) of the plate member <NUM>, the tip surface 11a of the plate member <NUM> is configured by: a side (line) 41a that connects the center in the width direction (X direction) and one of the both ends in the width direction (X direction); and a side (line) 41b that connects the center in the width direction (X direction) and the other of the both ends in the width direction (X direction). That is, the tip surface 11a is composed of two surfaces of a surface parallel to the side 41a and a surface parallel to the side 41b. An angle formed by the side 41a and the side 41b is an obtuse angle.

In the case of <FIG>, in a sectional view substantially perpendicular to the thickness direction (Y direction) of the plate member <NUM>, the tip surface 11a of the plate member <NUM> is configured from: two sides (lines) 42a, 42b that connect the center in the width direction (X direction) and one of the both ends in the width direction (X direction); and two sides (lines) 42c, 42d that connect the center in the width direction (X direction) and the other of the both ends in the width direction (X direction). That is, the tip surface 11a is composed of four surfaces of a surface parallel to the side 42a, a surface parallel to the side 42b, a surface parallel to the side 42c, and a surface parallel to the side 42d. An angle formed by the side 42a and the side 42b is an obtuse angle, an angle formed by the side 42a and the side 42c is an obtuse angle, and an angle formed by the side 42c and the side 42d is an obtuse angle. The tip surface 11a can also be configured by more surfaces.

In the case of <FIG>, in a sectional view substantially perpendicular to the thickness direction (Y direction) of the plate member <NUM>, the tip surface 11a of the plate member <NUM> is formed by a curved line having no corner. That is, the tip surface 11a is formed by a curved surface having no corner.

Claim 1:
An extrusion die (<NUM>) comprising:
an opening (<NUM>) for supplying a molten resin;
a plurality of die hole portions (<NUM>) for discharging a strand made of the molten resin;
a resin flow path portion (<NUM>) extending in a flow path direction (Y) that leads to the plurality of die hole portions (<NUM>) from the opening (<NUM>),
wherein the resin flow path portion (<NUM>) has a resin introduction portion (<NUM>) connecting
with the opening (<NUM>), and a slit portion (<NUM>) located on a downstream side of the resin introduction portion (<NUM>); and
a moving plate (<NUM>) movable in an up-and-down direction (Z) so as to protrude toward the resin flow path portion (<NUM>),
wherein the moving plate (<NUM>) is arranged along a first direction (X) orthogonal to each of the flow path direction (Y) and the up-and-down direction (Z),
both end portions of the moving plate (<NUM>) in the first direction (X) in an up-and-down direction (Z) so as to contact with an inner wall of the resin flow path portion (<NUM>), and
a protrusion amount (t1) of the moving plate (<NUM>) with respect to the resin flow path portion (<NUM>) decreases from a central portion in the first direction (X) toward the both end portions, and
the plurality of die hole portions (<NUM>) are coupled to a downstream-side end portion of the slit portion (<NUM>),
the first direction (X) is a width direction of the slit portion (<NUM>), and
the moving plate (<NUM>) is protruding toward the entire width of the slit portion (<NUM>) in a middle of the slit portion (<NUM>),
a width - (X) of the resin introduction portion (<NUM>) gradually increases from an upstream side toward a downstream side,
characterized in that
a width (X) of the slit portion (<NUM>) is larger than a width (X) of the opening (<NUM>), in that the moving plate (<NUM>) is protruding toward the slit portion (<NUM>) so that a tip surface (11a) of the moving plate (<NUM>) becomes lower than an upper surface (33a) of the slit portion (<NUM>), and
in that the tip surface (11a) of the moving plate (<NUM>) has a shape in which a height position gradually increases from a center point toward both ends in the first direction (X).