JP5952160B2 - Extruder die and extrusion molding machine - Google Patents

Description

  The present invention relates to an extruder die that is attached to the tip of an extruder and forms a rubber material supplied from the extruder into a tire constituent member having a predetermined cross-sectional shape, and an extruder having the same.

  Generally, when manufacturing pneumatic tires, each tire component such as inner liner, sidewall, bead, and tread is bonded together in an unvulcanized state to form a green tire, which is then vulcanized. To make it.

  The bead is composed of a bead wire serving as a reinforcing material and a bead filler made of rubber having a substantially triangular cross section. Conventionally, a bead filler is formed by extruding a band-shaped rubber having the above-mentioned cross-sectional shape from an extruder, cutting it into a certain length, and joining the ends thereof (for example, Patent Document 1 below).

  The base provided at the tip of the extruder has a discharge port corresponding to the cross-sectional shape of the tire constituent member. Thereby, the rubber material supplied from the extruder can be formed into a tire constituent member having a predetermined cross-sectional shape.

  However, depending on the cross-sectional shape of the extruded tire constituent member, there is a problem in that the shape of the tire becomes unstable due to the occurrence of edge cutting, undulation, and the like. For example, since the bead filler has a substantially triangular cross section as described above, the corner portion of the triangle has a particularly poor rubber flow, and ear cuts are likely to occur.

JP 2011-194854 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a die for an extruder and an extrusion molding machine that can extrude a tire constituent member that prevents ear cutting and has improved dimensional stability. .

The above object can be achieved by the present invention as described below. That is, the extruder die according to the present invention is an extruder die that is attached to the tip of the extruder and molds a rubber material supplied from the extruder into a tire constituent member having a predetermined cross-sectional shape,
A supply port to which the rubber material is supplied, a discharge port for discharging the rubber material, and a rubber flow path that connects the supply port and the discharge port,
The discharge port has an acute-angled edge that has an acute corner.
A mortar-shaped inclined surface inclined downward from the back surface on the supply port side toward the acute-angled edge is formed, and the rubber flow path is reduced toward the discharge port side. It is.

  The discharge port of the die for an extruder according to the present invention has an acute edge with an acute corner, that is, the extruded tire component has a cross-sectional shape with an acute corner. Become. Since the rubber flow is poor at such an acute edge portion of the discharge port, the rubber component is insufficient and the tire constituent member is likely to be cut off. The die for an extruder according to the present invention has a mortar-shaped inclined surface that is inclined downward from the back surface on the supply port side toward the acute-angled edge, and the rubber flow path is reduced toward the discharge port side. Therefore, it becomes easy to supply a large amount of rubber material supplied from the supply port to the acute angle edge portion, and the rubber flow at the acute angle edge portion of the discharge port is improved. As a result, it is possible to provide a die for an extruder that can extrude a tire constituent member that prevents ear cutting and has improved dimensional stability.

  In the die for an extruder according to the present invention, the inclined surface is preferably formed by a smooth surface. By forming the inclined surface as a smooth surface, the rubber flow along the inclined surface is improved, and the rubber flow at the acute-angled edge of the discharge port is effectively improved.

  In the die for an extruder according to the present invention, the inclined surface is preferably formed by a stepped surface including a plurality of tread surfaces intersecting the extrusion direction and a kick-up connecting the plurality of tread surfaces. . By forming the inclined surface with a stepped surface, the inclined surface can be easily machined. Thereby, the processing time of the inclined surface can be shortened and the processing dimension is stabilized.

  In the extruder die of the present invention, it is preferable that the height of the staircase rises gradually toward the discharge port. Moreover, in the die for an extruder according to the present invention, it is preferable that the length of the tread surface of the stairs gradually decreases toward the discharge port. According to these configurations, the volume of the rubber flow path in the vicinity of the supply port can be increased, and a large amount of rubber material can be supplied from the supply port. Therefore, it is easy to supply a large amount of rubber material to the sharp edge of the discharge port. Become.

  An extrusion molding machine according to the present invention includes any one of the above-described extruder caps and an extruder to which the extruder die is attached at the tip.

  The discharge port of the die for an extruder according to the present invention has an acute edge with an acute corner, that is, the extruded tire component has a cross-sectional shape with an acute corner. Become. Since the rubber flow is poor at such an acute edge portion of the discharge port, the rubber component is insufficient and the tire constituent member is likely to be cut off. The die for an extruder according to the present invention has a mortar-shaped inclined surface that is inclined downward from the back surface on the supply port side toward the acute-angled edge, and the rubber flow path is reduced toward the discharge port side. Therefore, it becomes easy to supply a large amount of rubber material supplied from the supply port to the acute angle edge portion, and the rubber flow at the acute angle edge portion of the discharge port is improved. As a result, it is possible to provide an extrusion molding machine capable of extruding a tire constituent member that prevents ear cutting and has improved dimensional stability.

  In the extrusion molding machine according to the present invention, a preform die for discharging the rubber material supplied from the extruder to the extruder die via a rubber outlet between the extruder and the extruder die. It is preferable that the supply port is smaller than the rubber discharge port. By making the supply port of the die for the extruder smaller than the rubber discharge port of the preform die, the rubber material from the extruder can be efficiently supplied to the die via the preform die.

Schematic configuration diagram showing the entire extrusion molding machine Front view of the extruder seen from the front in the extrusion direction Back view of the base viewed from the preform die side AA sectional view of the base of FIG. Rear view of a base according to another embodiment Sectional drawing of the nozzle | cap | die which concerns on another embodiment Sectional drawing of the nozzle | cap | die which concerns on another embodiment Cross-sectional view of a base according to an embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the entire extrusion molding machine. FIG. 2 is a front view of the extrusion molding machine as viewed from the front in the extrusion direction. The extrusion molding machine 1 of the present invention includes an extruder 2 and a preform die 3 and a die 4 (corresponding to an extruder die) connected to the tip of the extruder 2.

  The extruder 2 can knead the rubber material supplied from a hopper (not shown) inside and extrude it from the tip of the extruder. As the extruder 2, any conventionally known extruder can be used.

  The preform die 3 is provided between the extruder 2 and the die 4, and discharges the rubber material supplied from the extruder 2 to the die 4 through the rubber discharge port 31. The preform die 3 is connected to the tip of the extruder 2, more specifically, to the downstream side in the extrusion direction X of the extruder 2. In the preform die 3, a flow path for guiding the rubber material extruded from the extruder 2 to the die 4 is formed inside.

  The base 4 is attached to the tip of the extruder 2, more specifically, the downstream side in the extrusion direction X of the preform die 3, and the rubber material supplied from the extruder 2 is converted into a tire constituent member having a predetermined cross-sectional shape. It is to be molded. In the present embodiment, an example in which the extruded tire component is a bead filler 5 having a substantially triangular cross section is shown.

  The configuration of the base 4 will be described with reference to FIGS. 3 and 4. FIG. 3 is a rear view of the base 4 as seen from the back side, specifically from the preform die 3 side. 4 is a cross-sectional view of the base 4 of FIG.

  The base 4 has a substantially rectangular parallelepiped shape. The base 4 includes a supply port 41 through which a rubber material is supplied, a discharge port 42 through which the rubber material is discharged, and a rubber flow path 43 that connects the supply port 41 and the discharge port 42. The supply port 41 is provided on the back surface 4 a of the base 4, and the discharge port 42 is provided on the front surface 4 b of the base 4. In the present embodiment, the supply port 41 and the discharge port 42 have the same shape except for an inclined surface 44 to be described later, and the flow channel wall of the rubber flow channel 43 is a flat surface extending in parallel to the extrusion direction X. .

  In this embodiment, in order to extrude the bead filler 5 having a substantially triangular cross section, the discharge port 42 has a substantially triangular shape when viewed from the front. In this example, the discharge port 42 has three acute edge portions 42a, 42b, and 42c whose corner portions are acute angles. The sharp edge portions 42a, 42b, and 42c of the discharge port 42 have a poor rubber flow, so that the rubber material is insufficient and the bead filler 5 is likely to be cut off.

  The base 4 of the present invention is formed with a mortar-shaped inclined surface 44 that is inclined downward from the back surface 4a on the supply port 41 side toward the acute edge portions 42a, 42b, 42c. The inclined surface 44 has a shape in which a portion of a quadrangular pyramid having a sharp corner edge 42a, 42b, 42c as a head vertex and a rhombus on the bottom surface is cut out. Even when the inclined surface 44 is formed on the back surface of the base 4, the supply port 41 is smaller than the rubber discharge port 31 of the preform die 3.

  Since the mortar-shaped inclined surface 44 is formed on the back surface 4a of the base 4, the rubber flow path 43 is reduced from the supply port 41 side toward the discharge port 42 side. In particular, since the rubber flow paths around the acute-angled edges 42a, 42b, and 42c are reduced toward the discharge port 42, a large amount of rubber material supplied from the supply port 41 is removed from the acute-angled edges 42a, 42b, and 42c. The rubber flow at the acute edge portions 42a, 42b, 42c of the discharge port 42 is improved.

  Moreover, it is preferable that the tip side of the bead filler 5 has a larger amount of rubber material supplied than the heel side. The leading end side of the bead filler 5 is the right side of the drawing in FIG. 1, and the heel side of the bead filler 5 is the left side of the drawing in FIG. Since the rubber flow is worse on the tip side than on the heel side, there is a problem that the bead filler 5 is pushed out in an arc shape with the heel side being the outer peripheral side (also called banana shape). On the other hand, for example, the inclination angle of the inclined surface 44 corresponding to the acute angle edge portion 42c is made gentler than the inclination angle of the inclined surface 44 corresponding to the acute angle edge portions 42a and 42b. Thereby, the volume in the inclined surface 44 corresponding to the acute angle edge portion 42c becomes larger than the volume of the inclined surface 44 corresponding to the acute angle edge portions 42a and 42b, and the rubber material supplied to the acute angle edge portion 42c is changed to an acute angle. More than the rubber material supplied to the edges 42a, 42b.

  In the present invention, the mortar shape means that the cross-sectional area perpendicular to the extrusion direction X gradually decreases from the supply port 41 side toward the discharge port 42 side, and is a quadrangular pyramid shape as in this embodiment. In addition, the concept includes a hemispherical shape, a conical shape, and the like. In the present embodiment, the bottom of the mortar-shaped inclined surface 44 completely coincides with the acute-angled edge portions 42a, 42b, and 42c. Any form that is guided to the edges 42a, 42b, and 42c may be used.

  The inclined surface 44 of the present embodiment is formed by a stepped surface composed of a plurality of tread surfaces 441 that intersect with the extrusion direction X and a kick-up 442 that connects the plurality of tread surfaces 441 together. By forming the inclined surface 44 with a stepped surface, it becomes easy to machine the inclined surface 44 by a machine, the processing time of the inclined surface 44 can be shortened, and the processing dimensions are stabilized. In the present embodiment, the number of steps is three, but can be set as appropriate depending on the thickness of the die 4 in the extrusion direction, the shape of the discharge port 42, and the like.

  In the present embodiment, the length L of the plurality of tread surfaces 441 is constant, and the height H of the kick-up 442 is also constant. Further, the length L of the tread surface 441 and the height H of the kick-up 442 are the same. The length L of the tread surface is preferably 5 to 7 mm, and more preferably 2 to 4 mm from the viewpoint of preventing deterioration of rubber flow and facilitating machining. Similarly, the height H of the kick-up 442 is preferably 5 to 7 mm, more preferably 2 to 4 mm, from the viewpoint of preventing deterioration of rubber flow and facilitating machining.

<Another embodiment>
(1) In the above-described embodiment, the mortar-shaped inclined surface 44 has a rhombus-shaped cross section orthogonal to the extrusion direction X, but the inclined surface 44 has a circular shape (see FIG. 5) or an oval shape. The shape may be a polygon or the like.

  (2) In the above-described embodiment, the height of the stepped surface kick-up 442 is constant on the inclined surface 44, but the stepped height is gradually increased toward the discharge port 42 as shown in FIG. 6A. It is preferable to be smaller. Thereby, more rubber | gum can be supplied also to parts which are disadvantageous to rubber | gum supply, such as an acute angle part of a bead filler front-end | tip. In the example of FIG. 6A, the tread surface length L is constant and H1: H2: H3 = 3: 2: 1.

  (3) In the above-described embodiment, the length of the stepped surface 441 of the stepped surface is constant on the inclined surface 44, but the length of the stepped surface of the step is toward the discharge port 42 as shown in FIG. 6B. It is preferable to gradually decrease. Thereby, more rubber | gum can be supplied also to parts which are disadvantageous to rubber | gum supply, such as an acute angle part of a bead filler front-end | tip. In the example of FIG. 6B, the kick height H is constant, and L1: L2: L3 = 3: 2: 1.

  (4) In the above-described embodiment, the inclined surface 44 is formed by a stepped surface, but may be formed by a smooth surface. By forming the inclined surface 44 as a smooth surface, the rubber flow along the inclined surface 44 becomes good, and the rubber flow at the acute-angled edge portions 42a, 42b, 42c of the discharge port 42 is effectively improved. Further, when the inclined surface 44 is formed by a stepped surface, the connecting portion between the tread surface 441 and the kick-up 442 may be rounded so that the rubber flow is good.

  (5) The extruder die and the extruder according to the present invention are particularly useful when the tire constituent member to be extruded is a bead filler having a substantially triangular cross section, but also when it is a tread or the like. Useful.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation item in an Example etc. measured as follows.

(1) Defect rate of parts The bead filler was extruded 1000 m, and the proportion of parts that could not be adopted as parts due to ear cutting, undulation, unstable shape, etc. was measured. The index is evaluated with the conventional example as 100, and the smaller the score, the smaller the defect rate of the parts, and the better.

(2) Extrusion time The time for extruding the bead filler 1000 m was measured. The index is evaluated with the conventional example as 100, and the smaller the score, the shorter the extrusion time and the better.

Examples 1-5
Examples obtained by processing the inclined surfaces having the cross-sectional shapes shown in FIG. Table 1 shows the results of the above evaluation using such a die. In Type 1, the length of the tread surface and the height of the kick-up were fixed. In Type 2, the kick height was gradually reduced toward the discharge port. In Type 3, the tread surface length was gradually reduced toward the discharge port. Type 4 is the reverse of type 2 and the kick height is gradually increased toward the discharge port. Type 5 is the reverse of Type 3, and the tread length was gradually increased toward the discharge port.

Comparative Example A comparative example in which the inclined surface was not formed on the base and the cross-sectional area of the rubber channel was constant in the extrusion direction was used as a comparative example. Table 1 shows the results of the above evaluation using such a die.

  As shown in Table 1, in the caps according to Examples 1 to 5, the defective rate of parts is lower and the extrusion time is shorter than in the conventional example. Example 2 has a lower component defect rate than Example 5. In addition, the third embodiment has a lower component defect rate than the fourth embodiment.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Extruder 3 Preform die 4 Base 4a Back surface 5 Bead filler 31 Rubber discharge port 41 Supply port 42 Discharge port 42a Sharp corner edge portion 42b Sharp corner edge portion 42c Sharp corner edge portion 43 Rubber flow path 44 Inclined surface 441 Tread surface 442 Kick-up

Claims (5)

A die for an extruder that is attached to the tip of an extruder and molds a rubber material supplied from the extruder into a tire component having a predetermined cross-sectional shape,
A supply port to which the rubber material is supplied, a discharge port for discharging the rubber material, and a rubber flow path that connects the supply port and the discharge port,
The discharge port has an acute-angled edge that has an acute corner.
A mortar-shaped inclined surface inclined downward from the back surface on the supply port side toward the acute edge is formed, and the rubber flow path is reduced toward the discharge port side ,
The base for an extruder, wherein the inclined surface is formed by a stepped surface including a plurality of tread surfaces intersecting the extrusion direction and a kick-up connecting the plurality of tread surfaces . Riser height of the staircase, an extruder die according to claim 1, characterized in that gradually decreases toward the discharge port. 3. The extruder die according to claim 1, wherein a length of a stepped surface of the stairs gradually decreases toward the discharge port. 4. An extruder comprising the die for an extruder according to any one of claims 1 to 3 and an extruder to which the die for the extruder is attached at a tip. Between the extruder and the die for the extruder, a preform die for discharging the rubber material supplied from the extruder to the die for the extruder through a rubber discharge port,
The extrusion molding machine according to claim 4 , wherein the supply port is smaller than the rubber discharge port.

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