JP4694958B2 - Rubber coating head for cord and rubber coating device - Google Patents

Description

  The present invention relates to a rubber coating head for a cord and a rubber coating apparatus for the cord used for manufacturing a rubber coated cord used for reinforcing a rubber product.

  Conventionally, as a method for obtaining a rubber-coated cord, as shown in Patent Document 1, there is an extrusion-type rubber coating apparatus that sends a cord coated with rubber through a rubber-coated head connected to the outlet side of the extruder. Are known. As a rubber coating apparatus other than the extrusion system, as shown in Patent Document 2, a calendar-type rubber coating apparatus that coats rubber on a cord using a calendar roll is also known.

Comparing the two types of rubber coating devices described above, the extrusion-type device described in Patent Document 1 has a higher extrusion pressure than the calendar-type device, and has excellent rubber impregnation properties. As a result, the rubber-coated cord having excellent durability can be obtained.
Japanese Patent Application Laid-Open No. 2005-246736 Japanese Patent Laid-Open No. 2004-090589

  However, in the apparatus described in Patent Document 1, the axial direction of the die hole that feeds the rubber-coated cord is a direction orthogonal to the rubber supply direction from the extruder, and the die hole extends from the upstream side to the downstream side in the rubber supply direction. The pressure applied to the die holes varies between the upstream side and the downstream side in the rubber supply direction. As a result, the amount of rubber coated on the cord increases on the upstream side in the rubber supply direction, but decreases on the downstream side, and the thickness of the resulting rubber-coated cord may change.

  As described above, a rubber-coated cord drawn out in a state in which a plurality of cords are arranged is spirally wound around the surface of a rubber-coated product such as a pressure-resistant rubber tube and used to form a reinforcing layer of the rubber tube. Sometimes.

  At this time, if a rubber-coated cord, in which rubber is unevenly coated between the arranged cords, is used as a reinforcing material for a rubber product, the pressure retention fluctuates when the rubber product is used, leading to premature breakage of the product. There was a fear.

  Accordingly, in the present invention, in view of the above, there is provided a cord rubber coating head and a cord rubber coating device capable of suppressing variation in the amount of rubber adhesion to the cord and uniformly attaching rubber between the arranged cords. The purpose is to provide.

  In order to solve the above problems, the present invention comprises a rubber intake port for taking in a rubber composition from an extruder, and a plurality of die holes for coating the rubber composition on a plurality of cords and feeding them out as rubber-coated cords, respectively. In the rubber-coated head, the die hole is formed such that the hole diameter increases as the formation position is further away from the rubber inlet.

According to the above configuration, by adjusting the hole diameter of the die hole according to the distance from the rubber intake, it is possible to make the amount of rubber adhering to the cord delivered from each die hole uniform.
Here, the relationship between the position of the die hole with respect to the rubber inlet and the rubber flow rate from the die hole will be described. If the pressure (water head pressure) applied to the die hole D1 formed at a position close to the extruder is h1, and the pressure (water head pressure) applied to the die hole D2 formed at a position far from the extruder is h2, the rubber inlet Since the rubber pressure decreases with increasing distance from, h1> h2.

The rubber flow velocity U in each die hole is expressed by U = (2gh) ^1/2 from Bernoulli's theorem. The flow rate Q of rubber is Q = UA when the die cross-sectional area is constant at A. That is, the rubber flow rate Q1 flowing out from the die hole D1 is Q1 = A × (2gh1) ^{1/2 and} is larger than the rubber flow rate Q2 = A × (2gh2) ^1/2 flowing out from the die hole D2.

In order to make Q1 and Q2 equal, if the die sectional area of the die hole D2 is A2,
A × (2gh1) ^1/2 = A2 × (2gh2) ^1/2
∴A2 = A × (h1 / h2) ^1/2
It becomes. Here, since h1> h2, A2> A. That is, the rubber flow rates of Q1 and Q2 can be made uniform by making the hole diameter of the die hole D2 larger than the hole diameter of the die hole D1. Strictly speaking, the relational expression of the rubber flow velocity U is applied to a Newtonian fluid, and an error increases in a Bingham fluid such as a rubber composition, but the rubber flow velocity in each die hole is relatively set. It is possible to compare.

  Regarding the arrangement of the plurality of die holes in the rubber-coated head, specifically, the axial direction of each die hole is orthogonal to the rubber supply direction from the rubber intake, and each die hole is upstream in the rubber supply direction. The die hole diameter can be formed so as to be arranged along the downstream side from the side of the rubber and toward the downstream side in the rubber supply direction.

  To arrange the die holes from the upstream side to the downstream side in the rubber supply direction, specifically, the die holes can be arranged in a line on a straight line at regular intervals, and can also be arranged in two staggered rows. is there.

  When a large number of die holes are formed in the rubber-coated head, each die hole may be formed so that the hole diameter changes continuously little by little, but the difference in hole diameter between adjacent die holes is negligible. It also takes time to change the hole diameter for each die hole.

  Therefore, in the present invention, with respect to the arrangement of the plurality of die holes, the axial direction of each die hole is orthogonal to the rubber supply direction from the rubber intake, and each die hole is downstream from the upstream side in the rubber supply direction. A plurality of arranged die holes are divided into a plurality of pieces along the rubber supply direction, and the die hole diameter is formed to be larger toward the downstream side in the rubber supply direction. . In this way, by changing the diameter of the die holes in a stepwise manner, it is possible to easily form the die holes.

  If the rubber covering device for the cord is composed of the rubber covering head of the cord described above and further comprising an extruder for supplying the rubber composition to the rubber covering head and a take-off roller for taking out the rubber covering cord from the rubber covering head, Can be obtained in a state where a plurality of cords with uniformly attached are arranged.

  In the present invention, the die hole is formed such that the diameter of the die hole increases as the position of the die hole is farther from the rubber intake, so that the amount of rubber adhering to the cord fed from each die hole can be made uniform.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an extrusion type cord rubber coating apparatus using a cord rubber coating head according to the present invention. The rubber coating apparatus includes a rubber coating head 1, a cord supply unit 3 that supplies a cord 2 to the rubber coating head 1, an extruder 4 that extrudes the rubber composition while heating and kneading it, and supplies the rubber composition to the rubber coating head 1. A take-up roller 7 for pulling out the rubber-coated cord 6 from a plurality of die holes 5 formed in the rubber-coated head 1 is provided.

  The cord supply unit 3 supplies the cords 2 drawn from a plurality of bobbins (not shown) to the rubber-coated head 1 in an arranged state. The rubber-coated head 1 is formed with a rubber intake 8 for taking in the rubber composition. The rubber coating head 1 is connected to the outlet side of the extruder 4, and the rubber composition supplied from the extruder 3 is pushed out from the die hole 5 through the rubber inlet 8.

  Further, the rubber coating head 1 is configured such that a plurality of cords 2 arranged in the state introduced from the cord supply unit 3 are passed through the rubber composition and sent out from the die hole 5, thereby covering the cord 2 with rubber. It is supposed to be a structure. The type of the cord 2 is not particularly limited, and a cord made of nylon, polyester, rayon, aramid, steel or the like can be used. Among them, in particular, when a cord having a low rubber impregnation property such as a steel cord having a stranded wire structure is used, it is possible to obtain a rubber-coated cord in which the amount of rubber adhered is uniform and the rubber is impregnated into the cord.

  FIG. 2 is a front view of the rubber-coated head 3. As described above, the rubber-coated head 1 is formed with the rubber intake 8 and the plurality of die holes 5, and the rubber flow path 9 is formed between them. That is, the rubber composition supplied from the extruder 4 to the rubber-coated head 1 is taken from the rubber intake 8, passed through the rubber flow path 9, and pushed out from the die hole 5. The rubber flow path is tapered so as to become narrower toward the tip of the rubber-coated head 1, thereby suppressing a decrease in rubber pressure on the downstream side in the rubber supply direction A as much as possible. Yes.

  The formation position of the die hole 5 in the rubber-coated head 1 is such that the axial direction of the die hole 5 is orthogonal to the direction of the rubber composition flowing through the rubber flow path 9 from the rubber inlet 8, that is, the rubber supply direction A. Further, the die holes 5 are arranged in two rows in a staggered pattern from the upstream side to the downstream side in the rubber supply direction A. The number of the die holes 5 in the rubber-coated head 1 is not particularly limited. However, from the viewpoint of producing a clear pressure difference between the upstream side and the downstream side of the arranged die holes 5, the number of cords 2 to be used. The effect is particularly great when the number exceeds 100.

  The cord 2 introduced into the rubber-coated head 1 from the cord supply unit 3 passes through the rubber flow path 9 in the rubber-coated head 1 along the axial direction of the die hole 5. That is, the passing direction of the cord 2 is a direction orthogonal to the rubber supply direction A.

  The plurality of die holes 5 formed in the rubber-coated head 1 are divided into five sections 10a to 10e along the rubber supply direction A, and the diameters of the die holes of the sections 10a, 10b, 10c, 10d, and 10e are respectively set. It is formed at d1, d2, d3, d4 and d5.

  The relationship of the die hole diameter in each section is set so that the die hole diameter increases from the upstream side to the downstream side in the rubber supply direction, that is, d1 <d2 <d3 <d4 <d5. In this manner, the die hole diameter of the upstream section in the rubber supply direction A where the pressure applied to the die hole 5 is high is reduced, and the die hole diameter of the downstream section in the rubber supply direction A where the pressure applied to the die hole 5 is reduced is reduced. By reducing the size, the amount of rubber adhering to the cord 2 can be made uniform.

  The rubber-coated cord 6 obtained as described above can be used by being wound around the surface of a rubber-coated product while a plurality of the rubber-coated cords are arranged. It is also possible to store the obtained rubber-coated cord 6 once.

  In this case, a plurality of rubber-coated cords 6 in an arrayed state may be bonded to each other and integrated to be wound up as a corded rubber tape on a winding roller or the like.

  In order to integrate the rubber-coated cords, when the intervals between the rubber-coated cords are small, they can be bonded and integrated into a tape shape. Further, when the rubber-coated cord 6 is sandwiched and pulled out by the take-up roller 7, the rubber-coated cord can be bonded to each other by a pressing force of the take-up roller 7 to form a tape. In addition to the take-up roller 7, it is also possible to use a pressing roller that presses the rubber-coated cord 6 into a tape shape.

Schematic showing a rubber coating apparatus for cords according to the present invention Front view of rubber-coated head in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber coating head 2 Code 3 Cord supply part 4 Extruder 5 Die hole 6 Rubber coating cord 7 Take-off roller 8 Rubber intake 9 Rubber flow path A Rubber supply direction

Claims (4)

A rubber-coated head comprising a rubber inlet for taking a rubber composition from an extruder, and a plurality of die holes for coating the rubber composition on a plurality of cords and feeding them as rubber-coated cords, respectively. A cord-coated rubber-coated head characterized in that the hole diameter increases as the formation position is further away from the rubber inlet. The plurality of die holes are arranged such that the axial direction of each die hole is orthogonal to the rubber supply direction from the rubber intake, and each die hole is arranged from the upstream side to the downstream side in the rubber supply direction. 2. The cord rubber-coated head according to claim 1, wherein the cord is formed so that the die hole diameter increases toward the downstream side in the rubber supply direction. The plurality of die holes are arranged such that the axial direction of each die hole is orthogonal to the rubber supply direction from the rubber inlet, and each die hole is arranged from the upstream side to the downstream side in the rubber supply direction. 2. The plurality of formed and arranged die holes are divided into a plurality along the rubber supply direction, and the die hole diameter is formed so as to be larger toward the downstream side in the rubber supply direction. Cord rubber coated head. A rubber-coated head according to any one of claims 1 to 3, an extruder for supplying a rubber composition to the rubber-coated head, and a take-up roller for pulling a rubber-coated cord from the rubber-coated head. A rubber coating device for cords.

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