JP7614490B2 - Manufacturing method and apparatus for rubber-coated wire - Google Patents

Description

The present invention relates to a method and device for manufacturing a rubber-coated wire, and more specifically, to a method and device for manufacturing a rubber-coated wire that can adjust the opening of the outlet flow path for unvulcanized rubber extruded into the head of a rubber extruder, and pass a wire through the unvulcanized rubber filled in the head, thereby more stably achieving the target thickness of the unvulcanized rubber that is coated on the outer surface of the wire.

In the manufacturing process of rubber products such as tires, rubber-coated wires whose outer surface is covered with unvulcanized rubber are used. There are several known methods for coating wires with unvulcanized rubber. In a method using a so-called crosshead type rubber extruder, rubber-coated wires are produced by extruding unvulcanized rubber into the head of the rubber extruder and passing the wire through the head filled with unvulcanized rubber. As unvulcanized rubber is continuously extruded from the rubber extruder, excess unvulcanized rubber is allowed to overflow from the head through an outlet flow path.

The amount of overflow of unvulcanized rubber affects the thickness of the coating of unvulcanized rubber that covers the outer surface of the wire. If the amount of overflow is too large, the coating thickness will be small, and if it is too small, the coating thickness will be large. Conventionally, a bead manufacturing device has been proposed that automatically controls the wire movement speed and the relief valve opening based on information on the outer diameter of the rubber-coated wire and information on the head pressure of the rubber extruder to equalize fluctuations in the outer diameter of the rubber-coated wire (see Patent Document 1). By opening this relief valve, the excess unvulcanized rubber filled in the head overflows through the outflow channel.

In this manufacturing device, the relief valve opening is frequently changed based on the detected outer diameter information and head pressure information, and it takes a considerable amount of time for the change in relief valve opening to be reflected and for the outer diameter of the rubber-coated wire to stabilize. In other words, because the appropriate opening of the outflow flow path is not determined, there is room for improvement in making the outer diameter of the rubber-coated wire, in other words the coating thickness of the unvulcanized rubber, more stable at the target value.

Japanese Patent Application Publication No. 8-47984

The object of the present invention is to provide a method and device for manufacturing a rubber-coated wire that can adjust the opening of the outlet flow path for the unvulcanized rubber extruded into the head of a rubber extruder, and can more stably achieve the target thickness of the unvulcanized rubber coating on the outer surface of the unvulcanized rubber by passing the wire through the unvulcanized rubber filled in the head.

In order to achieve the above object, the method for producing a rubber-coated wire of the present invention comprises the steps of extruding an unvulcanized rubber to be used as a target unvulcanized rubber from a rubber extruder into a head to fill the rubber-coated wire, while allowing the excess target unvulcanized rubber to overflow from the head through an outlet flow path, and passing a wire through the target unvulcanized rubber filled in the head to coat the target unvulcanized rubber on the outer circumferential surface of the wire to produce the rubber-coated wire, the method for producing the rubber-coated wire comprises the steps of: producing the rubber-coated wire by using a standard unvulcanized rubber having a rubber viscosity index of a preset standard value and varying only the degree of opening of the outlet flow path in a plurality of ways, detecting the outer diameter of the rubber-coated wire while producing the rubber-coated wire by using a standard unvulcanized rubber having a rubber viscosity index of a preset standard value, and determining the standard correlation between the standard outer diameter and the degree of opening of the outlet flow path by setting one axis as the degree of opening and the other axis as the degree of opening of the outer diameter; the standard correlation is plotted on a two-dimensional orthogonal coordinate system having a target dimension, and when manufacturing the rubber-coated wire using the target unvulcanized rubber with the outer diameter of the rubber-coated wire set to a target value, a standard opening degree for which the outer diameter of the standard unvulcanized rubber is used as the target value is determined from the standard correlation and the target value of the standard unvulcanized rubber, the outer diameter is detected while manufacturing the rubber-coated wire using the target unvulcanized rubber under conditions of the standard opening degree, the outer diameter at the time when the detected outer diameter becomes stable is set as the actual outer diameter, a modified correlation is calculated by sliding the standard correlation in the two-dimensional orthogonal coordinate system so that the opening degree at the actual outer diameter satisfies the standard opening degree, the opening degree at the target value in this modified correlation is determined as an appropriate opening degree, and thereafter the rubber-coated wire is manufactured using the target unvulcanized rubber under conditions in which the standard opening degree is changed to the appropriate opening degree.

The rubber-coated wire manufacturing apparatus of the present invention includes a rubber extruder which extrudes unvulcanized rubber, a wire moving mechanism which passes a wire through the unvulcanized rubber extruded from the rubber extruder and filled in a head, and an on-off valve which opens and closes an outlet flow path formed in the head, so that the unvulcanized rubber covers the outer peripheral surface of the wire after it has passed through the unvulcanized rubber and excess unvulcanized rubber overflows from the head through the outlet flow path. The rubber-coated wire manufacturing apparatus further includes a data acquisition unit which grasps a rubber viscosity index of the unvulcanized rubber, The apparatus includes an on-off valve opening/closing mechanism, a control unit which controls the operation of the on-off valve to change the opening degree of the outlet flow passage, and an outer diameter sensor which detects the outer diameter of the manufactured rubber-coated wire, and the outer diameter of the rubber-coated wire is detected by the outer diameter sensor while the rubber-coated wire is manufactured by varying only the opening degree in a plurality of ways using a standard unvulcanized rubber whose rubber viscosity index grasped by the data acquisition unit is a preset standard value, and the outer diameter of the rubber-coated wire is detected by the outer diameter sensor while the outer diameter when the detected outer diameter becomes stable is set as a standard outer diameter, and a standard correlation between the standard outer diameter and the opening degree is grasped. and the standard correlation is input in advance to the control unit, and the standard correlation is plotted in a two-dimensional orthogonal coordinate system with one axis representing the magnitude of the opening degree and the other axis representing the magnitude of the outer diameter. When the rubber-coated wire is manufactured using a target unvulcanized rubber with the outer diameter of the rubber-coated wire set to a target value, a standard opening degree for the outer diameter of the standard unvulcanized rubber when the standard unvulcanized rubber is used is determined by the control unit from the standard correlation of the standard unvulcanized rubber and the target value, and the rubber-coated wire is manufactured using the target unvulcanized rubber under conditions where the opening degree is set to the standard opening degree. the outer diameter of the wire is detected by the outer diameter sensor while the wire is being manufactured, the outer diameter when the detected outer diameter becomes stable is regarded as the actual outer diameter, a modified correlation is calculated by sliding the standard correlation in the two-dimensional orthogonal coordinate system so that the opening degree at the actual outer diameter satisfies the standard opening degree, the opening degree at the target value in this modified correlation is determined by the control unit as an appropriate opening degree, and thereafter, the rubber-coated wire is manufactured using the target unvulcanized rubber under conditions in which the standard opening degree is changed to the appropriate opening degree.

According to the present invention, when manufacturing a rubber-coated wire with a target coating thickness, a standard opening degree with the target outer diameter when the standard unvulcanized rubber is used can be determined with high accuracy based on the standard correlation between the standard outer diameter and the opening degree, which is determined by manufacturing a rubber-coated wire using the standard unvulcanized rubber whose rubber viscosity index is a preset standard value, and the target value. Then, the actual outer diameter is detected while manufacturing the rubber-coated wire using the target unvulcanized rubber under the standard opening degree conditions. The difference between the target value and the actual outer diameter is mainly caused by the difference in the rubber viscosity index between the standard unvulcanized rubber and the target unvulcanized rubber. Therefore, the standard correlation is slid to calculate a corrected correlation so that the opening degree at the actual outer diameter satisfies the standard opening degree. The opening degree at the target value in this corrected correlation is determined as the appropriate opening degree, and the rubber-coated wire is manufactured using the target unvulcanized rubber under conditions where the standard opening degree is changed to the appropriate opening degree, thereby making it possible to more stably achieve the target coating thickness.

FIG. 2 is an explanatory diagram illustrating a rubber-coated wire manufacturing apparatus according to the present invention in a side view. FIG. 2 is an explanatory diagram illustrating the manufacturing apparatus of FIG. 1 in a plan view. FIG. 3 is a partially enlarged view of FIG. 2 . FIG. 2 is an explanatory diagram illustrating a cross-sectional view of a manufactured rubber-coated wire. FIG. 2 is a graph illustrating the change over time in the opening degree, the outer diameter, and the internal pressure of the rubber extruder during the manufacturing process of the rubber-covered wire. FIG. 2 is a graph illustrating the change over time in the opening degree, outer diameter, and internal pressure of a rubber extruder at an initial stage in the manufacturing process of a rubber-coated wire using standard unvulcanized rubber. FIG. 1 is a graph illustrating standard and modified correlations between outer diameter of rubber-covered wire and open area. FIG. 2 is a graph illustrating the standard correlation between the outer diameter of a rubber-covered wire and the degree of opening for each standard unvulcanized rubber having different rubber viscosities. FIG. 2 is a graph illustrating the relationship between the rubber viscosity of the unvulcanized rubber used in the rubber-coated wire, the internal pressure of the rubber extruder, and the outer diameter of the rubber-coated wire. FIG. 1 is a graph illustrating a standard correlation between the internal pressure of a rubber extruder and the opening degree when rubber-coated wires are produced using standard unvulcanized rubbers having different rubber viscosities. FIG. 2 is a graph illustrating the relationship between the rubber viscosity and rubber hardness of unvulcanized rubber used in the rubber-coated wire and the outer diameter of the rubber-coated wire. FIG. 2 is a graph illustrating the relationship between the rubber viscosity of unvulcanized rubber used in the rubber-coated wire, the torque required to drive the screw of a rubber extruder, and the outer diameter of the rubber-coated wire.

The method and device for manufacturing rubber-coated wire of the present invention will be specifically described below based on the embodiment shown in the figures.

A rubber-coated wire Wr shown in Fig. 4 is manufactured using a rubber-coated wire manufacturing apparatus 1 (hereinafter referred to as manufacturing apparatus 1) of the present invention shown in Figs. 1 to 3. The rubber-coated wire Wr is formed by coating the outer circumferential surface of a steel wire W with unvulcanized rubber R. Since the outer diameter d ₀ of the wire W is known, if the outer diameter d of the rubber-coated wire Wr is known, the coating thickness h of the unvulcanized rubber R in the rubber-coated wire Wr is also known. In other words, the coating thickness h = (outer diameter d - outer diameter d ₀ ) / 2. The rubber-coated wire Wr is formed, for example, into an annular shape and used as a bead core, which is a component of a tire.

This embodiment of the manufacturing device 1 includes a rubber extruder 2 that extrudes unvulcanized rubber R, a reel 4 around which wire W is wound and stored, a drum 5 that winds up the rubber-coated wire Wr, a rubber viscometer 7a and a pressure sensor 7b, an on-off valve 8, an on-off mechanism 9 that operates the on-off valve 8, an outer diameter sensor 10, and a control unit 11. In this embodiment, the manufacturing device 1 further includes a festoon unit 6.

The rotating drum 5 functions as a wire moving mechanism that moves the wire W from the reel 4 toward the drum 5. In this embodiment, a flange portion 5a that is continuous around the entire circumference of the outer circumferential surface of the drum 5 is protruding. The rubber viscometer 7a and the pressure sensor 7b function as a data acquisition unit that grasps the rubber viscosity index PN, which will be described later.

The rubber extruder 2 has a cylinder body 2a, a screw 2b disposed inside the cylinder body 2a, and a head 3 attached to the tip of the cylinder body 2a. The head 3 is formed with a wire inlet 3a, a wire outlet 3b, and an outlet flow path 3c. The wire inlet 3a and the wire outlet 3b are disposed in opposing positions, and the outlet flow path 3c is disposed on the underside of the head 3.

The screw 2b, which is driven to rotate by the drive motor 2c, moves the unvulcanized rubber R fed into the cylinder body 2a toward the head 3, heats it, and extrudes it into the head 3. This rubber extruder 2 is a so-called crosshead type. The inside of the head 3 is filled with unvulcanized rubber R, and excess unvulcanized rubber R overflows to the outside of the head 3 through the outflow channel 3c.

The head 3 is disposed midway along the path of movement of the wire W from the reel 4 to the drum 5, and the wire W unwound from the reel 4 enters the inside of the head 3 through the wire inlet 3a and exits from the inside of the head 3 through the wire outlet 3b. In this way, the wire W unwound from the reel 4 penetrates the head 3, which is filled with unvulcanized rubber R, and passes through the unvulcanized rubber R, with the unvulcanized rubber R adhering to its outer circumferential surface. Therefore, by penetrating and moving through the head 3, the wire W becomes a rubber-coated wire Wr and moves from the wire outlet 3b toward the drum 5.

The festoon unit 6 is disposed in the middle of the path of movement of the wire W (rubber-coated wire Wr) from the head 3 to the drum 5. The festoon unit 6 includes a driving roller 6a and a support roller 6b disposed opposite each other. The support roller 6b is disposed so as to be able to approach and move away from the driving roller 6a. The rubber-coated wire Wr manufactured by penetrating the head 3 moves toward the drum 5 after being wound around the driving roller 6a and the support roller 6b. The driving roller 6a, which is driven to rotate, moves the wire W (rubber-coated wire Wr) from the reel 4 toward the drum 5, so that the driving roller 6a also functions as a wire moving mechanism. The driving roller 6a is not limited to being disposed in the festoon unit 6, and can be disposed in another position. For example, the festoon unit 6 can be configured with a pair of support rollers 6b whose interval can be changed, and the driving roller 6a can be disposed between the festoon unit 6 and the rubber extruder 2 (head 3) and between the festoon unit 6 and the drum 5.

The length of the path of movement of the wire W from the reel 4 to the drum 5 becomes shorter when the support roller 6b moves closer to the drive roller 6a, and becomes longer when the support roller 6b moves away from the drive roller 6a. Therefore, the length of the path of movement is adjusted by the movement of the support roller 6b toward or away from the drive roller 6a. Therefore, even if the winding of the rubber-coated wire Wr by the drum 5 stops, by lengthening the path of movement, it is possible to continue producing the rubber-coated wire Wr without interrupting the extrusion of the unvulcanized rubber R by the rubber extruder 2.

The rubber viscometer 7a and the pressure sensor 7b functioning as data acquisition units grasp data on the rubber viscosity index PN. The rubber viscosity index PN is an index of rubber physical properties or equipment that is closely related to the fluctuation of the viscosity of the unvulcanized rubber R and is largely caused by the viscosity fluctuation, and includes the viscosity of the unvulcanized rubber R itself. Specific examples of the rubber viscosity index PN include the viscosity PNa and hardness PNb of the unvulcanized rubber R, the internal pressure PNc of the rubber extruder 2 when manufacturing the rubber-coated wire Wr, and the drive torque PNd required to rotate the screw 2b. At least one of these four items (PNa, PNb, PNc, PNd) may be used as the rubber viscosity index PN, and in this embodiment, the viscosity PNa of the unvulcanized rubber R or the internal pressure PNc of the rubber extruder 2 is used.

The data acquisition units 7a and 7b grasp the rubber viscosity index PN of the unvulcanized rubber R before it is coated on the outer peripheral surface of the wire W. The rubber viscometer 7a then acquires the viscosity PNa of the unvulcanized rubber R before it is fed into the rubber extruder 2. A known viscometer such as a Mooney viscometer can be used as the rubber viscometer 7a. Alternatively, the rubber extruder 2 can be equipped with a function for grasping the rubber viscosity, and a rubber viscometer that grasps the viscosity PNa of the unvulcanized rubber R in the rubber extruder 2 can be used. The data of the viscosity PNa grasped by the rubber viscometer 7a is input to the control unit 11.

This pressure sensor 7b is attached to the head 3 and acquires the internal pressure PNc of the head 3. Any known pressure sensor of various specifications can be used for the pressure sensor 7b. It is also possible to use a pressure sensor 7b that grasps the internal pressure PNc of the cylinder main body 2a. The data of the internal pressure PNc grasped by the pressure sensor 7b is input to the control unit 11.

When the hardness PNb of the unvulcanized rubber R is used as the rubber viscosity index PN, a known rubber hardness meter is used as the data acquisition unit. This rubber hardness meter acquires the hardness PNb of the unvulcanized rubber R before it is fed into the rubber extruder 2.

When the driving torque PNd required to rotate the screw 2b is used as the rubber viscosity index PN, a power meter or the like that detects the power consumption of the driving motor 2c when rotating the screw 2b is used as the data acquisition unit. This power meter detects the power consumption of the driving motor 2c when the unvulcanized rubber R is moved inside the cylinder body 2a toward the head 3, and the driving torque PNd is determined based on the detected power consumption. The data of hardness PNb and driving torque PNd acquired by the data acquisition unit are input to the control unit 11.

The on-off valve 8 opens and closes the outflow flow path 3c. The on-off mechanism 9 operates the on-off valve 8 to change the opening degree A of the outflow flow path 3c. The operation of the on-off mechanism 9 is controlled by the control unit 11. The on-off mechanism 9 may be a fluid cylinder or a rod that moves back and forth with a servo motor. When the on-off valve 8 closes 100% of the cross-sectional area of the outflow flow path 3c, when n% is closed, and when it is not closed at all, the opening degree A is 0%, n%, and 100%, respectively, and the opening degree A is set to be greater than 0% and less than or equal to 100%.

The outer diameter sensor 10 is disposed near the wire outlet 3b and detects the outer diameter d of the rubber-coated wire Wr immediately after it passes through the head 3. A non-contact type displacement sensor or the like can be used as the outer diameter sensor 10. The data of the outer diameter d detected by the outer diameter sensor 10 is input to the control unit 11.

The control unit 11 controls the manufacturing apparatus 1. Therefore, the operation of the screw 2b (drive motor 2c), drum 5, festoon unit 6, and on-off valve 8 (on-off mechanism 9) are controlled by the control unit 11. A computer is used for the control unit 11. In addition to the various data mentioned above, data such as the rotation speed of the screw 2b, drive roller 6a, and drum 5, the movement speed of the wire Wr penetrating the head 3, and data on the standard correlation CRc described below are input to the control unit 11. The control unit 11 performs various calculations using the input data.

As shown in Figure 5, in the manufacturing process of rubber-coated wire Wr, even if the same manufacturing equipment is used and the opening degree A is set to the same and manufacturing is performed under the same conditions, variations occur in the outer diameter d (coating thickness h) due to various factors such as differences in the lot of unvulcanized rubber R. Figure 5 illustrates the changes over time in the opening degree A, outer diameter d, and internal pressure PNb when rubber-coated wire Wr is manufactured by changing only the opening degree A and keeping other conditions constant.

The opening degree A is kept constant from the start of the process until elapsed time T1, at which point it is reduced and kept constant until T2, at which point it is increased. With the opening degree A at the beginning of the process, the outer diameter d stabilizes at Ts, but is smaller than the target value (dashed horizontal line), so in order to make the outer diameter d larger, the opening degree A is reduced at T1. As a result, the outer diameter d becomes larger and stabilizes, but is still larger than the target value (dashed horizontal line). Therefore, at T2, the opening degree A is increased to reduce the outer diameter d.

In this way, to set the outer diameter d to the target value, the degree of opening A is repeatedly changed. Furthermore, even if the degree of opening A is changed, there is a corresponding time lag until the change is reflected and the outer diameter d stabilizes. As a result, the outer diameter d (coating thickness h) will fluctuate. The internal pressure PNc also fluctuates in a similar manner to the outer diameter d. Therefore, in the present invention, the degree of opening A is appropriately set so that the outer diameter d (coating thickness h) can be more stably set to the target value.

The standard correlation CRc input to the control unit 11 is the relative relationship between the outer diameter d and the opening degree A of the rubber-coated wire Wr manufactured using standard unvulcanized rubber Rc, whose rubber viscosity index PN is a preset standard value. In more detail, the rubber-coated wire Wr is manufactured using standard unvulcanized rubber Rc, with only the opening degree A of the outlet flow path 3c being varied in a number of ways. As illustrated in FIG. 6, the opening degree A is maintained constant from the beginning of the rubber-coated wire Wr process. Then, the outer diameter d of the manufactured rubber-coated wire Wr is detected, and the outer diameter d at the time Ts when the detected outer diameter d becomes stable is set as the standard outer diameter dc. Referring to the data of the change over time of the outer diameter d in FIG. 6, there is a period during which the outer diameter d is constant, and the outer diameter d at the time Ts, which is the start point of that period, is the standard outer diameter dc.

The correlation between the standard outer diameter dc and the opening degree A at that time is the standard correlation CRc. By manufacturing the rubber-coated wire Wr with only the opening degree A being varied in multiple ways and acquiring data on the standard outer diameter dc and the opening degree A, the data on the standard correlation CRc illustrated in FIG. 7 can be grasped. In FIG. 7, the standard correlation CRc is a straight line, but it may also be a curve. To set the outer diameter d of the rubber-coated wire Wr manufactured using the standard unvulcanized rubber Rc to the target value Gd, the opening degree Ac at the intersection of the standard correlation CRc and the target value Gd in FIG. 7 (this is called the standard opening degree Ac) can be set. By grasping the standard correlation CRc, it is possible to accurately determine the standard opening degree Ac that can set the outer diameter d to the target value Gd when the rubber-coated wire Wr is manufactured using the standard unvulcanized rubber Rc.

The standard value of the rubber viscosity index PN can be set arbitrarily. For example, when rubber viscosity PNa is adopted as the rubber viscosity index PN, any desired rubber viscosity PNa is set as the standard value, and the unvulcanized rubber R whose rubber viscosity PNa is this standard value is used as the standard unvulcanized rubber Rc. If the unvulcanized rubber R used when actually manufacturing the rubber-coated wire Wr is defined as the target unvulcanized rubber Ru, the standard unvulcanized rubber Rc may have a different rubber viscosity index PN from the target unvulcanized rubber Ru. Alternatively, the standard unvulcanized rubber Rc may have the same rubber viscosity index PN as the target unvulcanized rubber Ru, and therefore the target unvulcanized rubber Ru can be used as the standard unvulcanized rubber Rc.

Next, an example of the procedure for manufacturing a rubber-coated wire Wr having a target outer diameter d of Gd using the target unvulcanized rubber Ru by the rubber-coated wire manufacturing method of the present invention will be described.

The target unvulcanized rubber Ru is fed into the rubber extruder 2 illustrated in Figures 1 to 3 as the unvulcanized rubber R, and the screw 2b is rotated by the drive motor 2c to extrude the target unvulcanized rubber Ru fed into the cylinder body 2a into the head 3. The inside of the head 3 is filled with the target unvulcanized rubber Ru. The rubber extruder 2 does not stop, and basically continuously extrudes the target unvulcanized rubber Ru at the same extrusion speed. Therefore, the excess target unvulcanized rubber Ru flows out of the head 3 as overflow rubber Rf through the open outflow flow path 3c. The overflow rubber Rf is fed back into the rubber extruder 2 and extruded to the head 3. The tip of the wire W is passed through the head 3 through the wire inlet 3a and wire outlet 3b, and is wound around the festoon section 6 and the drum 5.

By rotating the drive roller 6a and the drum 5, the wire W is unwound from the reel 4 and passes through the target unvulcanized rubber Ru filled inside the head 3. When passing through the target unvulcanized rubber Ru, the target unvulcanized rubber Ru adheres to the outer surface of the wire W, so that the outer surface of the wire W that has passed through the head 3 is covered with the target unvulcanized rubber Ru to produce a rubber-coated wire Wr. The manufactured rubber-coated wire Wr passes through the outer diameter sensor 10 and the festoon section 6 in order, moves to the drum 5, and is wound up. It is desirable to keep the moving speed of the wire W (rubber-coated wire Wr) substantially constant. In general, as the viscosity PNa decreases, the amount of unvulcanized rubber R adhering to the outer surface of the passing wire W increases, and the outer diameter d (coating thickness h) increases, and as the viscosity PNa increases, the amount of adhesion decreases, and the outer diameter d (coating thickness h) tends to decrease.

In this manufacturing process, the standard opening degree Ac is determined based on the standard correlation CRc and the target value Gd input to the control unit 11, as shown in FIG. 7, with the outer diameter d of the standard unvulcanized rubber CRc being the target value Gd. Then, the manufacturing of the rubber-coated wire Wr is started using the target unvulcanized rubber Ru under the conditions of the determined standard opening degree Ac.

Next, the outer diameter d of the rubber-coated wire Wr is detected by the outer diameter sensor 10 while it is being manufactured. The control unit 11 uses the outer diameter d at the point in time when the detected outer diameter d becomes stable as the actual outer diameter dx. In other words, the outer diameter d at the point in time Ts illustrated in FIG. 6 is regarded as the actual outer diameter dx.

Next, the control unit 11 calculates the modified correlation CRx by sliding the standard correlation CRc so that the opening degree A at the actual outer diameter dx satisfies the standard opening degree Ac, as illustrated in Fig. 7. In the standard correlation CRc in Fig. 7, the opening degree A at the actual outer diameter dx is larger than the standard opening degree Ac, so the modified correlation CRx is calculated by sliding the standard correlation CRc downward so that it passes through the intersection of the actual outer diameter dx and the standard opening degree Ac.

As shown in FIG. 7, the control unit 11 determines the opening degree A at the target value Gd in the corrected correlation CRx as the appropriate opening degree GA. Next, the opening mechanism 9 is controlled to move the opening valve 8 to change the standard opening degree Ac to the appropriate opening degree GA. Thereafter, the rubber-coated wire Wr is continuously manufactured using the target unvulcanized rubber Ru under the conditions of the appropriate opening degree GA.

The main reason why the outer diameter d of the rubber-coated wire Wr manufactured under the conditions of the standard opening degree Ac set using the standard correlation CRc becomes an actual outer diameter dx that differs from the target value Gd is the difference in the rubber viscosity index PN (rubber viscosity PNa) between the standard unvulcanized rubber Rc and the target unvulcanized rubber Ru. Therefore, as described above, in order to correct the difference in the rubber viscosity index PN, the standard correlation CRc is slid to calculate the corrected correlation CRx. Since the rubber-coated wire Wr is manufactured using the target unvulcanized rubber Ru under the conditions of the appropriate opening degree GA calculated based on the corrected correlation CRx and the target value Gd, it is possible to more stably set the outer diameter d to the target value Gd. In other words, by setting the appropriate opening degree GA, the coating thickness h can be more stably set to the target value.

In the present invention, the appropriate opening degree GA for the target unvulcanized rubber Ru to set the outer diameter d to the target value Gd is known, so by adjusting only the opening degree A among the manufacturing conditions, the fluctuation in the outer diameter d (coating thickness h) during the manufacturing process of the rubber-coated wire Wr can be made smaller than in conventional methods. As a result, the occurrence of defective products such as poor coating of the target unvulcanized rubber Ru is suppressed, which also contributes to improving the productivity of the rubber-coated wire Wr.

When unvulcanized rubber R with the same rubber viscosity index PN as the target unvulcanized rubber Ru is used as the standard unvulcanized rubber Rc, the standard correlation CRc and the modified correlation CRx become substantially the same. Therefore, this is advantageous for determining the appropriate opening degree GA with greater accuracy.

In this embodiment, the festoon section 6 retains the rubber-coated wire Wr according to the winding speed of the rubber-coated wire W by the drum 5, so that the wire W unwound from the reel 4 can be kept moving and the production of the rubber-coated wire Wr can be continued without interruption. Therefore, the extrusion of the unvulcanized rubber R by the rubber extruder 2 is not interrupted, and the unvulcanized rubber R can be extruded into the head 3 under basically constant extrusion conditions. When the extrusion conditions change, the physical properties of the extruded unvulcanized rubber R fluctuate. However, in this embodiment, the unvulcanized rubber R can be continuously extruded without changing the extrusion conditions, which is advantageous for producing rubber-coated wire Wr of stable quality.

If the rubber viscosity index PN (i.e., rubber viscosity PNa) of the standard unvulcanized rubber Rc is different, the slope of the data of the standard correlation CRc may also be different. If the degree of difference in the slope is large, it is disadvantageous to accurately calculate the appropriate opening degree GA. Therefore, it is advisable to prepare multiple types of standard unvulcanized rubber Rc with different rubber viscosity indexes PN and grasp the standard correlations CRc1, CRc2, and CRc3 for each type of standard unvulcanized rubber Rc, as illustrated in FIG. 8. For example, the standard correlations CRc1, CRc2, and CRc3 are grasped for standard unvulcanized rubber Rc with medium, high, and low levels of rubber viscosity PNa. The control unit 11 calculates the standard opening degrees Ac1, Ac2, and Ac3 for each standard unvulcanized rubber Rc based on the standard correlations Cc1, CRc2, and CRc3 and the target value Gd of the outer diameter d.

When manufacturing a rubber-coated wire Wr with an outer diameter d set to a target value Gd using the target unvulcanized rubber Ru, the control unit 11 selects one standard unvulcanized rubber Rc with a rubber viscosity index PN that is most similar to the target unvulcanized rubber Ru from among multiple types of standard unvulcanized rubber Rc with different rubber viscosity indexes PN. Then, using the standard correlation CRc (one of CRc1, CRc2, and CRc3 illustrated in FIG. 8) for the selected standard unvulcanized rubber Rc, the control unit 11 determines the standard opening degree Ac in the above-described procedure. Then, the control unit 11 calculates the corrected correlation CRx in the same procedure as described above to determine the appropriate opening degree GA, and manufactures the rubber-coated wire Wr. According to this method, even if the rubber viscosity index PN (rubber viscosity PNa) of the standard unvulcanized rubber Rc and the target unvulcanized rubber Ru is different, the appropriate opening degree GA can be calculated with high accuracy.

The rubber viscosity index PN, which includes hardness PNb, internal pressure PNc, and drive torque PNd, is closely related to fluctuations in viscosity PNa and has a high correlation, so it is possible to estimate it from the viscosity PNa. A preliminary test is conducted to understand the relationship between rubber viscosity PNa, internal pressure PNc, and outer diameter d, as illustrated in Figure 9. The higher the viscosity PNa of the unvulcanized rubber R inside the rubber extruder 2, the higher the internal pressure PNc of the head 3 and cylinder body 2a tends to be when extruding the unvulcanized rubber R. From these relationships, the correlation between the outer diameter d and internal pressure PNc can also be understood.

The data in FIG. 10 can be obtained by converting the vertical axis of the data in FIG. 8 from the outer diameter d (standard outer diameter dc) to the internal pressure PNc using the data in FIG. 8 and FIG. 9. That is, the correlation CR (CRc1, CRc2, CRc3) between the internal pressure PNc and the opening degree A that makes the rubber-coated wire Wr manufactured using the standard unvulcanized rubber Rc have the standard outer diameter dc can be grasped. In other words, the correlation CR between the standard outer diameter dc and the opening degree A can be indirectly grasped using the internal pressure PNc. Therefore, the standard opening degree Ac (Ac1, Ac2, Ac3) can be determined based on the correlation CR (CRc1, CRc2, CRc3) and the target value Gd, and the appropriate opening degree GA can also be determined. Therefore, the correlation CR (CRc1, CRc2, CRc3) illustrated in FIG. 10 can be input and stored in the control unit 11 and used when manufacturing the rubber-coated wire Wr.

Similarly, a preliminary test is also conducted for hardness PNb to understand the relationship between rubber viscosity PNa, hardness PNb, and outer diameter d, as illustrated in FIG. 11. The higher the viscosity PNa of the unvulcanized rubber R, the higher the hardness PNb tends to be. Since both viscosity PNa and hardness PNb are parameters of the rubber itself, the viscosity PNa is converted to hardness PNb using the data in FIG. 11. Then, in the same way as when viscosity PNa is used as the rubber viscosity index PN illustrated in FIG. 7 and FIG. 8, the appropriate opening degree GA can be determined and the rubber-coated wire Wr can be manufactured.

Similarly, a pre-test is performed for the driving torque PNd to grasp the relationship between the rubber viscosity PNa, the driving torque PNd, and the outer diameter d, as illustrated in FIG. 12. The higher the viscosity PNa of the unvulcanized rubber R inside the rubber extruder 2, the higher the driving torque PNd tends to be for extruding the unvulcanized rubber R. Therefore, by using the data in FIG. 8 and FIG. 12 and converting the vertical axis of the data in FIG. 8 from the outer diameter d (standard outer diameter dc) to the driving torque PNd, data similar to that in FIG. 10 can be obtained. That is, the correlation CR (CRc1, CRc2, CRc3) between the driving torque PNd that makes the rubber-coated wire Wr manufactured using the standard unvulcanized rubber Rc have the standard outer diameter dc and the opening degree A can be grasped. In other words, the correlation CR between the standard outer diameter dc and the opening degree A can be indirectly grasped using the driving torque PNd. Therefore, based on this correlation CR (CRc1, CRc2, CRc3) and the target value Gd, the standard opening degree Ac (Ac1, Ac2, Ac3) can be determined, and the appropriate opening degree GA can also be determined. Therefore, the correlation CR (CRc1, CRc2, CRc3) illustrated in FIG. 10 can be input to and stored in the control unit 11 and used when manufacturing the rubber-coated wire Wr.

1 Rubber-coated wire manufacturing apparatus 2 Rubber extruder 2a Cylinder body 2b Screw 2c Drive motor 3 Head 3a Wire inlet 3b Wire outlet 3c Outlet flow path 4 Reel 5 Drum (wire moving mechanism)
5a Flange portion 6 Festoon portion 6a Drive roller (wire moving mechanism)
6b Support roller 7a Rubber viscometer 7b Pressure sensor 8 Opening/closing valve 9 Opening/closing mechanism 10 Outer diameter sensor 11 Control unit W Wire Wr Rubber-coated wire R Unvulcanized rubber Rc Standard unvulcanized rubber Ru Target unvulcanized rubber Rf Overflow rubber

Claims (5)

In a method for producing a rubber-coated wire, an unvulcanized rubber to be used is designated as a target unvulcanized rubber, and the target unvulcanized rubber is extruded from a rubber extruder into a head to fill the head, while excess target unvulcanized rubber is allowed to overflow from the head through an outlet flow path, and a wire is passed through the target unvulcanized rubber filled in the head to coat the outer peripheral surface of the wire with the target unvulcanized rubber, thereby producing a rubber-coated wire,
a rubber-coated wire is manufactured using a standard unvulcanized rubber having a rubber viscosity index of a preset standard value, with only the degree of opening of the outlet flow passage being varied in a plurality of ways, while detecting the outer diameter of the rubber-coated wire, and the outer diameter at the time when the detected outer diameter becomes stable is taken as a standard outer diameter, and a standard correlation between this standard outer diameter and the degree of opening of the outlet flow passage is grasped, and the standard correlation is plotted in a two-dimensional orthogonal coordinate system with the degree of opening as one axis and the size of the outer diameter as the other axis;
When manufacturing the rubber-coated wire with the outer diameter of the rubber-coated wire set to the target value using the target unvulcanized rubber, a standard opening degree is determined based on the standard correlation of the standard unvulcanized rubber and the target value, which will result in the outer diameter of the standard unvulcanized rubber being set to the target value when the standard unvulcanized rubber is used;
a modified correlation coefficient calculated by sliding the standard correlation coefficient in the two-dimensional orthogonal coordinate system so that the opening degree at the actual outer diameter satisfies the standard opening degree; a modified correlation coefficient calculated by sliding the standard correlation coefficient in the two-dimensional orthogonal coordinate system so that the opening degree at the actual outer diameter satisfies the standard opening degree; and a modified correlation coefficient calculated by sliding the standard correlation coefficient in the two-dimensional orthogonal coordinate system so that the opening degree at the target value in the modified correlation coefficient is determined as an appropriate opening degree. The method for manufacturing a rubber-coated wire according to claim 1, comprising the steps of: preparing a plurality of types of standard unvulcanized rubber with different rubber viscosity indices; determining the standard correlation for each type of standard unvulcanized rubber; selecting one of the plurality of types of standard unvulcanized rubber whose rubber viscosity index is closest to that of the target unvulcanized rubber; determining the standard opening degree using the standard correlation for the selected one standard unvulcanized rubber; and calculating the corrected correlation to determine the appropriate opening degree. The method for manufacturing a rubber-coated wire according to claim 1, wherein the standard unvulcanized rubber is an unvulcanized rubber having the same rubber viscosity index as the target unvulcanized rubber. The method for manufacturing a rubber-coated wire according to any one of claims 1 to 3, wherein at least one of the following is used as the rubber viscosity index: rubber viscosity, rubber hardness, the internal pressure of the rubber extruder when manufacturing the rubber-coated wire, and the torque required to drive the screw of the rubber extruder. A rubber-coated wire manufacturing apparatus having a rubber extruder which extrudes unvulcanized rubber, a wire moving mechanism which passes a wire through the unvulcanized rubber extruded from the rubber extruder and filled in a head, and an on-off valve which opens and closes an outlet flow path formed in the head, wherein the unvulcanized rubber coats the outer peripheral surface of the wire after it has passed through the unvulcanized rubber, and excess unvulcanized rubber overflows from the head through the outlet flow path,
a data acquisition unit that grasps a rubber viscosity index of the unvulcanized rubber, an opening/closing mechanism for the on-off valve, a control unit that controls the operation of the opening/closing mechanism to change the opening degree of the outflow flow path, and an outer diameter sensor that detects the outer diameter of the manufactured rubber-coated wire,
a standard unvulcanized rubber having a rubber viscosity index grasped by the data acquisition unit which is a preset standard value is used to manufacture the rubber-coated wire by varying only the opening degree in a plurality of ways, the outer diameter of the rubber-coated wire is detected by the outer diameter sensor, and the outer diameter at the time when the detected outer diameter becomes stable is taken as a standard outer diameter, and a standard correlation between this standard outer diameter and the opening degree is grasped and inputted in advance to the control unit, and the standard correlation is plotted in a two-dimensional orthogonal coordinate system having one axis representing the degree of opening and the other axis representing the outer diameter,
When manufacturing the rubber-coated wire with the outer diameter of the rubber-coated wire set to the target value using the target unvulcanized rubber , the control unit determines a standard opening degree that makes the outer diameter of the standard unvulcanized rubber the target value when the standard unvulcanized rubber is used, based on the standard correlation of the standard unvulcanized rubber and the target value;
a control unit that calculates a modified correlation by sliding the standard correlation in the two-dimensional orthogonal coordinate system so that the opening degree at the actual outer diameter satisfies the standard opening degree, the control unit determining the opening degree at the target value in this modified correlation as an appropriate opening degree, and thereafter, the rubber-coated wire is manufactured using the target unvulcanized rubber under conditions in which the standard opening degree is changed to the appropriate opening degree.

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