JP2021142646A - Bead filler molding method - Google Patents

Abstract

To provide a bead filler molding method capable of suppressing curling of an outer peripheral portion after molding.SOLUTION: A bead filler 9 forming method forms an annular bead filler 9 on an outer peripheral side of an annular bead core 8, and comprises the steps of: arranging the bead core 8 on a molding surface 3a; forming a molding space surrounded by a tip surface of an extruder base 2, the outer peripheral surface of the bead core 8, and the molding surface 3a, by bringing the base 2 closer to an outer peripheral side of the bead core 8; and molding a bead filler 9 having the same cross-sectional shape as the molding space, by rotating the molding surface 3a around a central axis of the bead core 8 while filling the molding space with rubber extruded from an opening formed on the tip surface of the base 2. A shape of the opening is smaller than the cross-sectional shape of the bead filler 9.SELECTED DRAWING: Figure 2B

Description

The present disclosure relates to a bead filler molding method.

In the following Patent Document 1, the die component attached to the head of the extruder and the molding surface of the die assisting device are brought into contact with each other in a direction orthogonal to or intersecting with each other, and the die assisting device is rotated at a predetermined speed. The rubber-like elastic material is extruded from the head toward the outer peripheral surface side of the annular reference member provided on the molding surface of the die assisting device, and the annular shape of the die component member and the molding surface of the die assisting device has a predetermined cross-sectional shape. A method of molding an annular member for molding a member is described.

The annular member of Patent Document 1 is, for example, a bead filler having a substantially triangular cross section, but the bead filler after molding may curl the outer peripheral portion due to shrinkage due to relaxation of residual strain.

Japanese Unexamined Patent Publication No. 2005-335244

An object of the present disclosure is to provide a bead filler molding method capable of suppressing curling of an outer peripheral portion after molding.

The bead filler molding method of the present disclosure is a bead filler molding method for molding an annular bead filler on the outer peripheral side of an annular bead core.
The step of arranging the bead core on the molding surface and
A step of bringing the mouthpiece of the extruder close to the outer peripheral side of the bead core to form a molding space surrounded by the tip surface of the mouthpiece, the outer peripheral surface of the bead core, and the molding surface.
The bead having the same cross-sectional shape as the molding space is formed by rotating the molding surface around the central axis of the bead core while filling the molding space with rubber extruded from an opening formed in the tip surface of the mouthpiece. With the process of molding the filler,
The shape of the opening is smaller than the cross-sectional shape of the bead filler.

According to this configuration, the strain generated in the bead filler during molding is reduced, and curling of the outer peripheral portion after molding can be suppressed.

Perspective view showing an example of a bead filler molding apparatus Front view showing the main part of the bead filler molding apparatus Front view showing the main part of the bead filler molding apparatus Front view and bottom view of the base Front view and bottom view of the base according to another embodiment Front view showing the main part of the bead filler molding apparatus according to another embodiment. Bottom view of the base according to another embodiment

Hereinafter, an embodiment of the bead filler molding method will be described with reference to the drawings.

As shown in FIG. 1, the bead filler molding apparatus 1 includes an extruder (not shown), a base 2 for discharging rubber extruded from the extruder from an opening 21, and a rotating table 3. The bead filler molding apparatus 1 is attached to the molding surface 3a of the rotating table 3 by an extruder while extruding the rubber in a strip shape through the mouthpiece 2 and sticking it around once, and the ends of the strip-shaped rubber are joined to each other to form an annular shape. Mold the bead filler 9.

In the present embodiment, as shown in FIG. 1, an example is shown in which a band-shaped rubber having a tapered cross-sectional triangular shape is molded into an annular shape to obtain an annular bead filler 9. An annular bead core 8 is joined to the radial inner peripheral surface 9a of the bead filler 9. The bead filler 9 is formed of hard rubber, and the bead core 8 is formed of a convergent body such as a steel wire. The bead core 8 is held by a bead lock mechanism 32 provided on the table 3. The rotation axis 31 of the table 3 is coaxial with the central axis of the bead core 8.

The bead filler 9 has a cross-sectional shape of a substantially right triangle, and has a radial inner peripheral surface 9a corresponding to the base of the triangle, an upright side surface 9b corresponding to one hypotenuse of the triangle, and the other hypotenuse of the triangle. It has a corresponding hypotenuse 9c. The radial inner peripheral surface 9a is in contact with the outer peripheral surface of the bead core 8, the upright side surface 9b is in contact with the molding surface 3a of the table 3, and the inclined side surface 9c is in contact with the base 2. In the cross section of the bead filler 9, the size of the inner peripheral surface 9a in the radial direction is referred to as the filler thickness, and the size of the upright side surface 9b is referred to as the filler width. As described above, since the outer peripheral portion of the bead filler 9 has a shape thinner than that of the inner peripheral portion, the outer peripheral portion tends to curl due to shrinkage due to relaxation of residual strain. Therefore, in order to suppress curling of the outer peripheral portion, it is desired to mold the bead filler 9 so that no strain remains.

Although not shown, the extruder has a hopper into which the rubber material is charged, a screw that pushes the rubber material forward while applying heat, and the like. In the extruder, the amount of rubber extruded is controlled to, for example, a constant amount by controlling the rotation speed of the screw by a control device (not shown). In the present embodiment, the rotating shaft of the rubber extrusion screw built in the extruder is arranged in parallel with the rotating shaft 31 of the table 3.

The base 2 has a tip surface 2a in which the opening 21 is formed. The tip surface 2a is arranged so as to be inclined with respect to the molding surface 3a so that the distance of the table 3 from the molding surface 3a is larger on the inner peripheral side than on the outer peripheral side. The inclination angle θ of the tip surface 2a with respect to the molding surface 3a is set to be the same as the angle formed by the upright side surface 9b and the inclined side surface 9c of the bead filler 9 to be molded. Further, the end surface on the outer peripheral side of the tip surface 2a is formed so as to be parallel to the molding surface 3a. Further, the end surface on the inner peripheral side of the tip surface 2a is formed so that the inclination angle with respect to the molding surface 3a is larger than θ so as not to come into contact with the bead core 8.

In the present embodiment, the rubber extruded from the opening 21 is formed in the molding space 4 (see FIG. 2A) surrounded by the tip surface 2a of the base 2, the outer peripheral surface 8a of the bead core 8, and the molding surface 3a of the table 3. The table 3 is rotated around the rotation shaft 31 while being filled with. As a result, as shown in FIG. 2B, the bead filler 9 having substantially the same cross-sectional shape as the molding space 4 can be molded. At this time, the radial inner peripheral surface 9a of the bead filler 9 is crimped to the outer peripheral surface 8a of the bead core 8.

The base 2 is provided with a rubber flow path (indicated by a broken line in FIG. 2A and the like) through which rubber supplied from the extruder passes, and an opening 21 is formed on the downstream side thereof. The base 2 is arranged so that the rubber extrusion direction is perpendicular to the molding surface 3a of the table 3, in other words, parallel to the rotation axis 31 of the table 3.

The shape of the opening 21 is smaller than the cross-sectional shape of the bead filler 9. In FIG. 3, the cross-sectional shape of the bead filler 9 is shown by a two-dot chain line for comparison of the shapes. As shown in FIG. 3, the opening 21 has a substantially right-angled triangular shape that is one size smaller than the outer shape of the bead filler 9. The opening 21 has a horizontally long shape as shown in FIG. 3, and the longitudinal direction is referred to as a width direction and the lateral direction is referred to as a height direction.

Since the rubber extruded from the opening 21 in the high pressure state expands (swells) under the atmospheric pressure state, in the present embodiment, the shape of the opening 21 is made smaller than the cross-sectional shape of the target bead filler 9. ing. However, if the cross-sectional area of the rubber expanded after being extruded from the opening 21 is larger than the cross-sectional area of the bead filler 9, the rubber is scraped by the tip surface 2a of the base 2 and becomes smaller and exits from the molding space 4. Therefore, distortion remains in the bead filler 9. On the other hand, if the cross-sectional area of the rubber expanded after being extruded from the opening 21 is smaller than the cross-sectional area of the bead filler 9, the rubber is laminated and filled and then exits from the molding space 4, so that the bead filler 9 is used. Distortion remains. Therefore, it is preferable that the cross-sectional area of the rubber expanded after being extruded from the opening 21 is 100 to 105% of the cross-sectional area of the bead filler 9 by adjusting the shape of the opening 21 and the extrusion speed. It is more preferable that the cross-sectional area of the bead filler 9 is the same.

Further, if the cross-sectional shape of the rubber extruded from the opening 21 is significantly different from the cross-sectional shape of the bead filler 9 (cross-sectional shape of the molding space 4) such as a rectangular shape or an elliptical shape, the bead filler 9 is molded. Since the rubber is greatly deformed during the operation, a large strain remains in the bead filler 9. Therefore, in the present embodiment, the shape of the opening 21 is close to the cross-sectional shape of the bead filler 9. Specifically, in the state where the base 2 is arranged at the position where the molding space 4 is formed, the shape of the opening 21 is narrowed from the inner peripheral side to the outer peripheral side in the same manner as the cross-sectional shape of the bead filler 9. The outer peripheral part has a tapered shape. According to this configuration, the strain generated in the bead filler 9 during molding becomes smaller. It is particularly preferable that the shape of the opening 21 is set so that the rubber expanded after being extruded from the opening 21 has the same cross-sectional shape and the same cross-sectional area as the bead filler 9.

The height 21h of the opening 21 that defines the filler thickness of the bead filler 9 is A times the filler thickness 9h. Further, the width 21w of the opening 21 that defines the filler width of the bead filler 9 is B times the filler width 9w. Since the rubber extruded from the opening 21 tends to have a larger expansion coefficient in the height direction of the opening 21 than in the width direction, A and B satisfy the relationship of A <B.

Next, a method for forming the bead filler 9 will be described. First, the bead core 8 is arranged on the molding surface 3a of the table 3. At this time, the central axis of the bead core 8 is arranged so as to be coaxial with the rotation axis 31 of the molding surface 3a. The bead core 8 is fixed by the bead lock mechanism 32.

Next, the base 2 of the extruder is brought close to the outer peripheral side of the bead core 8 to form a molding space 4 surrounded by the tip surface 2a of the base 2, the outer peripheral surface 8a of the bead core 8, and the molding surface 3a. The cross-sectional shape of the molding space 4 is the same as the desired cross-sectional shape of the bead filler 9.

Next, the molding surface 3a is rotated around the rotation shaft 31 while filling the molding space 4 with the rubber extruded from the opening 21 of the base 2. As a result, the rubber is molded into the bead filler 9 having a desired cross-sectional shape on the tip surface 2a of the base 2 while being conveyed in the rotational direction of the molding surface 3a.

As described above, the bead filler molding method according to the present embodiment is a bead filler molding method for molding the annular bead filler 9 on the outer peripheral side of the annular bead core 8.
The process of arranging the bead core 8 on the molding surface 3a and
A step of bringing the base 2 of the extruder close to the outer peripheral side of the bead core 8 to form a molding space 4 surrounded by the tip surface 2a of the base 2, the outer peripheral surface 8a of the bead core 8, and the molding surface 3a.
By rotating the molding surface 3a around the central axis of the bead core 8 while filling the molding space 4 with the rubber extruded from the opening 21 formed in the tip surface 2a of the base 2, the molding space 4 has the same cross-sectional shape as the molding space 4. The process of molding the bead filler 9 is provided.
The shape of the opening 21 is smaller than the cross-sectional shape of the bead filler 9.

According to this bead filler molding method, the strain generated in the bead filler 9 during molding is reduced, and curling of the outer peripheral portion after molding can be suppressed.

Further, in the bead filler molding method according to the present embodiment, the height 21h of the opening 21 that defines the filler thickness 9h of the bead filler 9 is A times the filler thickness 9h, and the filler width 9w of the bead filler 9 is defined. The width 21h of the opening 21 to be formed may be A <B when it is B times the filler width 9w. According to this configuration, the rubber extruded from the opening 21 has a larger expansion coefficient in the height direction of the opening 21 than in the width direction, so that the cross-sectional shape of the expanded rubber is closer to the cross-sectional shape of the bead filler 9. Become.

Further, in the bead filler molding method according to the present embodiment, the shape of the opening 21 is set so that the rubber expanded after being extruded from the opening 21 has the same cross-sectional shape and the same cross-sectional area as the bead filler 9. May be done. According to this configuration, the strain generated in the bead filler 9 during molding becomes smaller.

Further, in the bead filler molding method according to the present embodiment, the base 2 may be arranged so that the width center of the opening 21 is offset toward the bead core 8 side from the width center of the molding space 4. According to this configuration, the bead filler 9 can be crimped by the outer peripheral surface 8a of the bead core 8, so that a gap is formed between the outer peripheral surface 8a of the bead core 8 and the radial inner peripheral surface 9a of the bead filler 9. Can be prevented.

Although the embodiments of the present disclosure have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present disclosure is shown not only by the description of the above-described embodiment but also by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

It is possible to adopt the structure adopted in each of the above embodiments in any other embodiment. The specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present disclosure.

(1) In the bead filler molding method according to the above embodiment, the cross-sectional shape of the bead filler 9 is a substantially right triangle, but the present invention is not limited to this. The cross-sectional shape of the bead filler 9 may be, for example, a substantially isosceles triangle.

(2) Further, the cross-sectional shape of the bead filler 9 is not limited to a triangle. That is, the cross-sectional shape of the bead filler 9 may be a polygon in which the outer peripheral side is gradually thinned from the inner peripheral side as shown in FIG.

(3) Further, the bead filler forming method according to another embodiment shown in FIGS. 5A and 5B is a bead filler forming method for forming an annular bead filler on the outer peripheral side of the annular bead core 8.
The process of arranging the bead core 8 on the molding surface 3a and
The process of molding the first bead filler portion 91 on the outer peripheral side of the bead core 8 and
A step of bringing the base 20 of the extruder close to the outer peripheral side of the bead core 8 to form a molding space surrounded by the tip surface 20a of the base 20, the outer peripheral surface 91a of the first bead filler portion 91, and the molding surface 3a.
By rotating the molding surface 3a around the central axis of the bead core 8 while filling the molding space with rubber extruded from the opening 210 formed in the tip surface 20a of the base 20, the molding space has the same cross-sectional shape as the molding space. The step of molding the second bead filler portion 92 is provided.
The shape of the opening 210 is close to the cross-sectional shape of the second bead filler portion 92 and smaller than the cross-sectional shape of the second bead filler portion 92.

According to this bead filler molding method, a bead filler composed of a first bead filler portion 91 and a second bead filler portion 92 can be molded, and the strain generated in the second bead filler portion 92 during molding is reduced. , It is possible to prevent the outer peripheral portion from curling after molding.

The first bead filler portion 91 may be molded by the bead filler molding method according to the above embodiment, but the first bead filler portion 91 is directly molded by extruding rubber from a mouthpiece having a moldable opening. You may.

(4) In the bead filler molding method according to the above embodiment, the shape of the opening 21 is smaller than the cross-sectional shape of the bead filler 9 as a whole, but the present invention is not limited to this. For example, the width 21w of the opening 21 may be made equal to the filler width 9w, and only the height 21h of the opening 21 may be smaller than the filler thickness 21h.

1 ... bead filler molding device, 2 ... base, 2a ... tip surface, 3 ... table, 3a ... molding surface, 4 ... molding space, 8 ... bead core, 8a ... bead core outer peripheral surface, 9 ... bead filler, 9h ... filler thickness , 9w ... Filler width, 21 ... Opening, 21h ... Opening height, 21w ... Opening width, 31 ... Rotating shaft

Claims (4)

A bead filler molding method for molding an annular bead filler on the outer peripheral side of an annular bead core.
The step of arranging the bead core on the molding surface and
A step of bringing the mouthpiece of the extruder close to the outer peripheral side of the bead core to form a molding space surrounded by the tip surface of the mouthpiece, the outer peripheral surface of the bead core, and the molding surface.
The bead having the same cross-sectional shape as the molding space is formed by rotating the molding surface around the central axis of the bead core while filling the molding space with rubber extruded from an opening formed in the tip surface of the mouthpiece. With the process of molding the filler,
A bead filler molding method in which the shape of the opening is smaller than the cross-sectional shape of the bead filler. The height of the opening that defines the filler thickness of the bead filler is A times the filler thickness, and the width of the opening that defines the filler width of the bead filler is B times the filler width. The bead filler molding method according to claim 1, wherein A <B. The bead filler according to claim 1 or 2, wherein the shape of the opening is set so that the rubber expanded after being extruded from the opening has the same cross-sectional shape and the same cross-sectional area as the bead filler. Molding method. The bead filler molding method according to claim 2, wherein the mouthpiece is arranged so that the width center of the opening is offset toward the bead core side from the width center of the molding space.

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