JPH10193474A - Control of rubber diameter for coating bead wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a rubber diameter after coating almost uniformly even during the acceleration and deceleration of the linear speed of a bead wire. SOLUTION: At the time of acceleration, as shown by a line diagram of a solid line A, the inclination of the speed of a rubber extruder is made larger than that of a broken line diagram at a steady time. By this constitution, delay of rubber extrusion quantity is corrected. At the time of deceleration, as shown by a line diagram of a solid line B, the inclination of the speed of the rubber extruder is made less than that of the broken line diagram at the steady time. By this constitution, excessive rubber extrusion quantity is corrected. The relation between the line diagrams A, B is set to a hysteres is relation and, even if the linear speed of a bead wire is same, the rotational speed of an extruder at the time of acceleration is different from that at the time of deceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extruding rubber for covering a bead wire with an extruder, and in a steady state, the number of rotations of an extruding rotary body for determining the amount of the rubber to be extruded is determined by changing the number of rotations of the bead wire. The present invention relates to a method of controlling a rubber diameter for bead wire coating for controlling the velocity in a directly proportional relationship obtained by multiplying the velocity by a predetermined coefficient and maintaining the coated rubber diameter at a predetermined value.

[0002]

2. Description of the Related Art One of the components of a tire, a bead,
It is configured by coating a core material called a bead wire with rubber.

[0003] The bead wire is transported in a long state at a predetermined linear speed, and a rubber extruder is provided in the middle of the transport. In this rubber extruder, a rubber puddle is provided at a tip portion between round gaps whose diameters are adjusted, and a bead wire is configured to pass through the gap. When the extruder is rotated in this state, the rubber is gradually extruded from the gap to cover the bead wire.

Here, the amount of rubber extruded is determined by the number of revolutions of the extruder. It is the linear velocity of the bead wire that determines the rotation speed of the extruder. That is, the linear speed of the bead wire and the rotational speed of the extruder are in direct proportion, and the rotational speed of the extruder is controlled by multiplying a predetermined coefficient according to the linear speed of the bead wire.

In the above case, the characteristic (linear velocity-rotational velocity)
Is linear as shown in FIG. 5, and a uniform outer diameter can be theoretically obtained when the bead wire is covered with rubber.

It is to be noted that a slight change in the linear speed of the bead wire can be neglected, and the rotational speed of the extruder can be kept within a permissible range even if the rotational speed of the extruder is constant.

[0007]

However, the input / output dynamic characteristics of the extruder (the input rotation speed by the extruder, the output: the discharge amount, the extrusion pressure) have a delay element, and the bead wire line When the speed greatly changes, that is, during acceleration and deceleration, it may not be possible to follow up. For example, at the time of acceleration, the discharge amount and the extrusion pressure cannot keep up with each other, so that the rubber diameter becomes small or so-called rubber flakes may occur. At the time of deceleration, for the same reason,
The problem that the rubber diameter becomes large occurs.

[0008] If the control is performed in a conventional direct proportional relationship, the rubber diameter cannot be made constant both during acceleration and deceleration, and the material is wasted until the rubber becomes stable.

In view of the above facts, the present invention provides a method for controlling a rubber diameter for coating a bead wire, which can keep the rubber diameter after coating substantially uniform even when the linear velocity of the bead wire is increasing or decreasing. The purpose is to get.

[0010]

According to the first aspect of the present invention, when rubber for covering a bead wire is extruded by an extruder, in a steady state, an extruding rotary body for determining an amount of extruded rubber is used. A method for controlling the diameter of a bead wire covering rubber for controlling the number of revolutions in a directly proportional relationship obtained by multiplying the linear velocity of the bead wire by a predetermined coefficient, and maintaining the coated rubber diameter at a predetermined value. During the acceleration of the linear velocity, the rotation speed of the rotating body is set to be higher than that at the time of the normal state by increasing the coefficient of the predetermined proportional relationship in the steady state, and during the deceleration of the linear velocity of the bead wire,
The rotation speed of the rotating body is made lower than that in the steady state by making it smaller than the coefficient of the direct proportional relation in the predetermined steady state, so that the characteristics during the acceleration and during the deceleration have hysteresis characteristics. It is characterized by:

According to the first aspect of the present invention, when the bead wire is being conveyed at a predetermined linear speed (during steady operation),
By rotating the extruder at a constant rotation speed, the rubber diameter after coating can be kept constant.

When the bead wire is accelerated, the rotational speed of the extruder is increased in accordance with the change. On the other hand, even during the deceleration, the rotation speed of the extruder is reduced in accordance with the change. in this case,
Conventionally, a constant coefficient, that is, the linear speed of the bead wire and the rotation speed of the extruder are controlled in a direct proportional relationship, so that a delay element is not taken into account and the rubber diameter after coating is not uniform.

However, according to the first aspect of the present invention, during acceleration of the bead wire, the number of rotations of the rotating body is made higher than that in the steady state by making the coefficient larger than a predetermined coefficient of the direct proportional relation in the steady state. During the deceleration of the linear speed of the bead wire, the rotation speed of the rotating body was made lower than that in the steady state by making the coefficient smaller than the predetermined coefficient of the direct proportional relation in the steady state. In other words, the characteristics during acceleration and during deceleration are made to have a hysteretic characteristic, so that a delay element of the input / output characteristics is added, and the rubber diameter after coating can be made uniform even during acceleration and deceleration. Becomes For this reason, the product during acceleration and deceleration is not wasted, and the yield is improved.

[0014]

FIG. 1 is a schematic diagram of a bead manufacturing line according to the present embodiment.

A plurality of bead wires 100 serving as a core material
Is long and wound around a wire reel 102 and accommodated therein. A heating unit 104 is provided downstream of the wire reel 102. The heating unit 104 has, for example, a structure in which an electric wire 108 is wound around an outer periphery of a ceramic cylindrical body 106 in a coil shape, and the bead wire 100 passes through the inner space of the cylindrical body 106. ing.

A high-frequency inverter 110 is connected to the electric wire 108.
, An eddy current is generated when passing through the bead wire 100, and the eddy current causes the bead wire 100 to be inductively heated by the function of Joule heat.

On the downstream side of the heating unit 104, an extruder 112
The extruder 112 is fed with the preheated bead wire 100, coated with rubber,
A bead 114 is formed. Extruder 1
The rubber outlet 12 is provided with a round rubber gap at its discharge port, and the extruder screw is rotated by the driving force of the motor 116, and the rubber is discharged from the rubber gap toward the bead wire 100 with this rotation. It has become. That is, the amount of rubber discharged depends on the rotation speed of the extruder.

A pull roll section 118 is disposed downstream of the extruder 112. The pull roll unit 118 is composed of a plurality of extruders 120, and a part of the extruders 120 is rotated by the driving force of a motor 122 to produce the rubber-coated beads 114.

The extruder 11 is driven by the driving force of the
2 is controlled based on the linear speed of the bead wire 100 by the driving force of the motor 122.

In the present embodiment, the relationship between the linear speed of the wire reel 100 (by the driving force of the motor 122 of the pull roll unit 118) and the rotation speed of the extruder 112 by the driving force of the motor 116 is shown in FIG. It is like
The chain line in FIG. 2 is a diagram showing the relationship when the bead wire 100 is being conveyed at a constant speed.
Is transported at a constant speed, the rotational speed of the extruder may be determined based on the chain line.

By the way, when the bead wire 100 is accelerated and the rotational speed of the extruder is increased in the diagram shown by the chain line in FIG. 2, the rubber extrusion amount cannot keep up with the delay element of the input / output dynamic characteristics. In other words, the diameter of the rubber becomes smaller than the rated rubber diameter, or so-called dusting occurs.

For this reason, during acceleration, that is, when the linear velocity of the bead wire 100 is continuously changing in a direction of increasing, as shown in the solid line A in FIG. Greater than the slope of This corrects the delay in the amount of rubber extruded. In addition, when the linear velocity of the bead wire 100 is equal to or higher than a predetermined value (the point XL in FIG. 2), even if the rotational speed of the extruder is increased, as shown in the extension line A ′ of the diagram A, the rubber coating diameter is hardly increased. Since no change is observed, this time is set as the upper limit of the rotation speed of the extruder, and thereafter, the rotation speed is set to a constant value. Thus, at the time of the upper limit speed of the bead wire 100 (point XU in FIG. 2), the diagram A
Will be consistent with the steady-state characteristics.

On the other hand, during deceleration, that is, when the bead wire 10
When the linear velocity of 0 is continuously decreasing, the gradient is made smaller than that in the steady-state diagram, as shown in the diagram of the solid line B in FIG. This corrects an excessive amount of rubber extrusion.

The relationship between the diagram A and the diagram B in FIG. 2 is a relationship having a hysteresis characteristic, and differs between acceleration and deceleration even if the bead wire 100 has the same linear velocity. It is the rotation speed of the extruder. When the linear velocity of the bead wire 100 becomes constant during the acceleration and the deceleration, the control target is returned to the chain line in FIG.

The operation of the present embodiment will be described below. When the bead wire 100 is being transported at a steady state, that is, at a constant speed, the rotation speed of the extruder 112 corresponding to the transport speed is determined based on the chain line diagram in FIG. Thereby, the discharge amount of rubber can be made an appropriate amount, and the rubber diameter after coating can be made substantially uniform.

Next, when it is desired to increase the transport speed of the bead wire 100, it is necessary to accelerate the current transport speed. If the rotation speed of the extruder of the extruder 112 is set based on the dashed line diagram in FIG. 2 during this acceleration, the amount of rubber actually discharged becomes insufficient due to the delay in input / output dynamic characteristics. Thus, during acceleration, the rotation speed of the extruder of the extruder 112 is determined based on the diagram of the solid line A in FIG.

That is, based on the characteristic that the inclination is larger by a predetermined ratio than the normal (dashed line in FIG. 2), the extruder 112
Since the rotation speed of the extruder is controlled, the amount of discharged rubber is increased. With this increase, the delay element of the input / output dynamic characteristic can be offset, and the rubber diameter after coating can be made substantially equal to that at the time of steady state.

When the bead wire 100 reaches the target conveying speed, the rotation speed of the extruder of the extruder 112 is returned to the normal control (control based on the chain line in FIG. 2), and thereafter, the stable rubber discharge amount is maintained. be able to.

Next, when it is desired to reduce the transport speed of the bead wire 100, it is necessary to reduce the current transport speed. If the rotational speed of the extruder 112 is set based on the dashed line diagram in FIG. 2 during this deceleration, the amount of rubber actually discharged becomes excessive due to a delay in input / output dynamic characteristics. Therefore, during deceleration, the extruder 1 is controlled based on the solid line B in FIG.
Twelve rotation speeds are determined.

That is, based on the characteristic that the inclination is smaller by a predetermined ratio than normal (the chain line in FIG. 2), the extruder 112
Since the rotation speed of the extruder is controlled, the amount of rubber discharged is reduced. Due to this decrease, the delay element of the input / output dynamic characteristics can be offset, and the rubber diameter after coating can be made almost the same as in the steady state.

When the bead wire 100 reaches the target conveying speed, the rotational speed of the extruder 112 is returned to the control at the time of steady state (control based on the chain line in FIG. 2) after a certain period of time, and thereafter, the stable rubber discharge amount is maintained. be able to. (Experimental example) The wire diameter of the bead wire 100 was 2.1 mm, the diameter of the extruder 112 was 75 mm, the reduction ratio of the extruder 112 (with respect to the motor shaft) was 1 / 44.707, and the extrusion die diameter (the round gap diameter of the rubber pool) was 3.1. FIG. 3B shows an experimental example in the case where the line speed is set to 0 to 500 m / min. FIG. 3A shows a conventional example.

It is to be noted that the steady-state inclination is set to 1.5, the acceleration inclination is set to 1.67, and the deceleration inclination is set to 1.0 (see FIG. 3).

As a result of this experiment, the target rubber diameter of the bead wire 100 after covering the wire diameter of 2.1 mm is 2.6 mm, but the experiment result is controllable in the range of 2.5 to 2.7 mm, and the dispersion is larger than the conventional one. Range can be reduced to half.

[0034]

As described above, the method for controlling the diameter of a rubber for covering a bead wire according to the present invention can maintain the rubber diameter after the coating substantially uniform even when the linear velocity of the bead wire is accelerating or decelerating. It has an excellent effect that it can be produced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a bead manufacturing line according to the present embodiment.

FIG. 2 is a characteristic diagram showing a relationship between a linear speed of a bead wire and a rotation speed of an extruder extruder according to the present embodiment.

FIG. 3A is an experimental example of conventional control, and FIG.
FIG. 4 is a characteristic diagram showing a change in coated rubber diameter, showing an experimental example under the control of the present embodiment.

FIG. 4 is a characteristic diagram showing specific numerical values of an experimental example based on the characteristics in FIG.

FIG. 5 is a characteristic diagram showing a relationship between a linear speed of a bead wire and a rotation speed of an extruder according to a conventional example.

[Explanation of symbols]

 100 bead wire 104 heating section 112 extruder 114 bead 118 pull roll section

Claims (1)

[Claims] When extruding rubber for covering a bead wire with an extruder, in a steady state, the number of rotations of an extruding rotating body for determining the amount of rubber extruded is determined by applying a predetermined coefficient to the linear velocity of the bead wire. A control method of the rubber diameter for bead wire coating for controlling in a directly proportional relationship multiplied and maintaining the coated rubber diameter at a predetermined value, wherein during linear acceleration of the bead wire, a predetermined steady state The rotational speed of the rotating body is made higher than that in a steady state by making it larger than the coefficient of the proportional relation, and during the deceleration of the linear velocity of the bead wire, the coefficient is made smaller than the coefficient of the linear relation in a predetermined steady state. The rotational speed of the rotating body is made lower than that in a steady state, and the characteristic during acceleration and the characteristic during deceleration have hysteresis characteristics to each other. Your way.