JP5964119B2 - Method for forming annular rubber member - Google Patents

Description

  The present invention relates to a method for forming an annular rubber member typified by a bead filler as a tire constituent member.

  As shown in FIG. 10, the tire is configured by combining various rubber members such as a sidewall rubber 2, a tread rubber 3, a carcass ply 4, and an inner liner rubber 5. The bead member 10 is disposed in each of the pair of bead portions 1, and the end portion in the width direction of the carcass ply 4 is wound back so as to sandwich the bead portion 10. As shown in FIG. 11, the bead member 10 includes an annular bead filler 1b made of hard rubber having a triangular cross section and a bead core 1a made of a convergent body such as a rubber-coated steel wire.

  For example, as shown in FIG. 12, the bead member 10 supplies the bead filler 1b extruded into a belt shape through the base 82 by the extruder 81 to the bead core 1a formed in an annular shape in advance, It is manufactured by bonding the bead core 1a (see Patent Document 1 below). The bead core 1a is supported so as to be rotatable in the r direction, and the rotation speed is controlled so as to correspond to the extrusion speed of the bead filler 1b. The bead filler 1b is cut into a predetermined length, and then the ends thereof are bonded together to form an annular shape.

  However, when the belt-shaped bead filler 1b is formed into an annular shape as described above, a circumferential tensile stress acts on the outer peripheral portion of the bead filler 1b due to the difference between the inner and outer peripheries thereof, and thus the bead filler 1b becomes the bead core 1a. It may be deformed in the opposite direction (X direction) and hinder the pasting of the ends. In particular, in the case of the bead filler 1b, since the outer peripheral portion is thin, the rubber flow in the outer peripheral portion tends to be worse than the inner peripheral portion in the rubber flow path inside the base 82, and the above-described problems are remarkable. there were.

  In the following Patent Document 2, the rubber flow rate in the outer peripheral flow path of the base is made larger than the rubber flow rate in the inner peripheral flow path, so that more rubber is fed into the outer peripheral portion of the base and pushed out. A method for forming an annular rubber member capable of bending a belt-like rubber is described. Thereby, a deformation | transformation of a strip | belt-shaped rubber | gum can be suppressed, and edge parts can be bonded together appropriately and it can shape | mold accurately in a ring shape.

  However, when the extruded rubber band is cut at a predetermined length and the ends are bonded together to form an annular shape, a step or separation is likely to occur at the joint. In addition to the extruder, additional equipment such as a cutting device is required.

JP-A-6-297603 JP 2009-61691 A

  The present invention has been made in view of the above circumstances, and its purpose is to suppress the deformation due to the difference between the inner and outer circumferences when joining the ends of the belt-like rubber extruded by an extruder to form an annular shape, An object of the present invention is to provide a method for forming an annular rubber member that can join end portions with high accuracy.

  The above object can be achieved by the present invention as described below. That is, in the method for molding an annular rubber member according to the present invention, the rubber is stuck in an annular shape while extruding the rubber in a band shape through a die by an extruder on a rotating table, and the ends of the band rubber are joined together. A method for forming an annular rubber member, wherein a base is brought close to the table from a vertical direction, extrusion of a band-shaped rubber is started, an amount of extrusion from the base is increased to a predetermined amount, and the base is A sticking start process that gradually separates from the table to a certain distance, a sticking process that sticks the belt-like rubber in an annular shape while maintaining the extrusion amount from the base at a predetermined amount, and immediately before the sticking of the belt-like rubber An end-of-sticking step for joining the end portions of the belt-shaped rubber by reducing the amount of extrusion from the base from a predetermined amount, and an opening having a shape corresponding to the cross-sectional shape of the belt-shaped rubber, and an outer peripheral portion of the opening An outer peripheral side flow rate in the outer peripheral side flow path, and a base having an outer peripheral side flow path for sending a rubber and an inner peripheral side flow path for sending rubber into the inner peripheral portion of the opening, A belt shape extruded by increasing / decreasing the extrusion amount from the base by increasing / decreasing the inner peripheral rubber flow rate in the inner peripheral flow path and increasing the outer peripheral rubber flow rate to be larger than the inner peripheral rubber flow rate. It is for curving rubber.

  According to the method for molding an annular rubber member of the present invention, the outer peripheral portion of the opening is formed by making the outer peripheral rubber flow rate in the outer peripheral flow channel of the base larger than the inner peripheral rubber flow rate in the inner peripheral flow channel. In contrast, when the belt-like rubber extruded by the extruder is formed into an annular shape, deformation due to the difference between the inner and outer circumferences can be suppressed. Further, in the sticking start process, the thickness of the starting end of the belt-shaped rubber can be gradually increased by increasing the amount of extrusion from the base to a predetermined amount and gradually separating the base from the table to a certain distance. On the other hand, by reducing the amount of extrusion from the die from a predetermined amount in the step of finishing the sticking, the thickness of the end portion of the belt-like rubber can be gradually reduced. Thereby, when joining the edge parts of strip | belt-shaped rubber | gum, the thickness in a junction part becomes substantially the same as the thickness of another part, and edge parts can be joined accurately.

  In the method for forming an annular rubber member of the present invention, the flow rate ratio between the outer peripheral side rubber flow rate and the inner peripheral side rubber flow rate in the pasting start step and pasting end step is different from the flow rate ratio in the pasting step. Is preferred.

  The amount of extrusion from the die can be increased or decreased by increasing or decreasing the outer peripheral rubber flow rate and the inner peripheral rubber flow rate. For example, when the thickness of the annular rubber member is different between the outer peripheral portion and the inner peripheral portion, that is, the opening When the height of the outer peripheral part differs from the inner peripheral part, the extrusion amount from the die is increased or decreased while maintaining the flow rate ratio between the outer peripheral side rubber flow rate and the inner peripheral side rubber flow rate in the pasting start process and the pasting end process. In some cases, the annular rubber member may not have a desired cross-sectional shape at the joint portion between the end portions. By making the flow rate ratio between the outer peripheral rubber flow rate and the inner peripheral rubber flow rate different from the flow rate ratio in the pasting process in the pasting start process and pasting end process, the cross-sectional shape at both ends of the belt rubber can be controlled appropriately. Thus, the ends can be joined with higher accuracy.

  In the method for molding an annular rubber member according to the present invention, an outer peripheral portion of the annular rubber member is thinner than an inner peripheral portion, and the inner circumference of the outer peripheral rubber flow rate in the pasting start step and the pasting end step. It is preferable to make the ratio with respect to the side rubber flow rate smaller than the ratio in the attaching step.

  When the outer peripheral part of the annular rubber member is thinner than the inner peripheral part, that is, when the outer peripheral part of the opening is lower than the inner peripheral part, By merely increasing or decreasing the amount of extrusion from the base while maintaining the ratio to the peripheral rubber flow rate, the outer peripheral portion of the annular rubber member may become larger than the desired thickness at the joint portion between the end portions. By reducing the ratio of the outer peripheral rubber flow rate to the inner peripheral rubber flow rate in the sticking start process and the sticking end process to be smaller than the ratio in the sticking process, the thickness of the outer peripheral portion is reduced at both ends of the belt-like rubber. The annular rubber member can be formed in a desired cross-sectional shape even at the joint portion between the end portions.

  The method for molding an annular rubber member of the present invention is particularly useful when the annular rubber member is a bead filler having a triangular cross-section with a tapered outer peripheral portion. Even with the bead filler whose outer peripheral portion is thin, according to the present invention described above, the end portions can be joined with high accuracy while suppressing deformation due to the inner and outer peripheral differences. The method for molding an annular rubber member of the present invention is also useful when the annular rubber member is a sidewall rubber. Even if the sidewall rubber has a relatively large difference between the inner and outer circumferences, according to the present invention described above, the end portions can be joined with high accuracy while suppressing deformation due to the difference between the inner and outer circumferences.

Schematic configuration diagram showing the entire annular rubber member molding apparatus A plan view of the molding apparatus of FIG. Schematic configuration diagram showing an example of an extruder and a die Perspective view of the base viewed from the opening side A perspective sectional view showing an example of an annular rubber member Explanatory drawing for demonstrating the formation process of an annular | circular shaped rubber member Schematic showing how the ends of the rubber band are joined together The figure which shows an example of control of the screw speed of the extruder in a sticking start process and a sticking end process Multiple cross-sectional views at the joint of the annular rubber member Multiple cross-sectional views at the joint of an annular rubber member (reference example) Sectional drawing which shows an example of a pneumatic tire Perspective view showing a partially broken bead member The figure which shows a mode that a bead member is manufactured by the conventional method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, an example is shown in which an annular rubber member is formed into an annular shape having a cross-sectional shape in which an outer peripheral portion as shown in FIG. 4 is thinner than an inner peripheral portion. FIG. 1A is a schematic configuration diagram showing the entire annular rubber member molding apparatus. FIG. 1B is a plan view of the molding apparatus of FIG. 1A as viewed from above. FIG. 2 is a schematic configuration diagram illustrating an example of an extruder and a die.

  The molding apparatus includes a base 15, an extruder that extrudes rubber in a band shape via the base 15 (in this embodiment, two extruders 20 and 30), and a control device 40, and a position facing the base 15. The table 50 is further provided. The extruder 20 includes a hopper 21 into which a rubber material is charged, a screw 22 that feeds the rubber material forward, a cylindrical barrel 23 that contains the screw 22, and a drive device 24 that drives the screw 22. Is provided. The extruder 30 is configured in the same manner as the extruder 20 and includes a hopper 31, a screw 32, a barrel 33, and a drive device 34. The control device 40 controls the amount of driving and rotation of the screws 22 and 32.

  The base 15 is connected to the front end side of the barrels 23 and 33 of the extruders 20 and 30, and the belt-like rubber S is extruded from the opening 11 formed on the front surface thereof. The extruded rubber band S is curved in the direction of arrow R1, as will be described later. FIG. 3 is a perspective view of the base 15 as viewed from the opening side. In FIG. 3, the belt-like rubber S is indicated by a broken line. As shown in FIG. 3, the opening 11 has a shape corresponding to the cross-sectional shape of the belt-like rubber S, and the right side of the drawing is the outer peripheral part 11 o of the opening 11 and the left side is the inner peripheral part 11 i of the opening 11.

  The base 15 includes a branch portion 12 and a junction portion 13. In addition, in this example, although the branch part 12 and the confluence | merging part 13 are comprised by a separate member, you may comprise by one member. Inside the base 15, a rubber flow path through which the rubber supplied from the extruders 20 and 30 passes is provided, and an opening 11 is formed on the downstream side thereof. The branch part 12 has an outer peripheral side flow path 12 o and an inner peripheral side flow path 12 i, which join at the junction part 13. The outer peripheral flow path 12 o communicates with the outer peripheral side of the merging portion 13 and feeds the rubber supplied by the extruder 20 into the outer peripheral portion 11 o of the opening 11. The inner peripheral flow path 12 i communicates with the inner peripheral side of the merging portion 13 and feeds the rubber supplied by the extruder 30 into the inner peripheral portion 11 i of the opening 11. In the present embodiment, the outer peripheral flow path 12o and the inner peripheral flow path 12i have substantially the same cross-sectional area.

  When molding the annular rubber member, first, rubber materials are put into the hoppers 21 and 31, and are fed forward while being kneaded by the screws 22 and 32, and supplied to the base 15. The rubber supplied to the base 15 is merged at the merge section 13 through the outer circumferential side channel 12o and the inner circumferential channel 12i, and the belt-like rubber S having a desired cross-sectional shape is pushed out from the opening 11. At this time, the rubber mainly sent via the outer peripheral side flow path 12o is fed into the outer peripheral part 11o of the opening 11, and the rubber mainly sent via the inner peripheral side flow path 12i is sent into the inner peripheral part 11i of the opening 11. .

  And in this invention, when extruding the strip | belt-shaped rubber | gum S, the outer peripheral side rubber flow rate in the outer peripheral side flow path 12o is made larger than the inner peripheral side rubber flow rate in the inner peripheral side flow path 12i. Thereby, more rubber | gum can be sent with respect to the outer peripheral part 11o of the opening 11, and the strip | belt-shaped rubber | gum S extruded as shown in FIG. 2 can be curved. Since the belt-like rubber S is not curved by pulling, deformation due to the difference between the inner and outer circumferences is suppressed.

  As a specific method for making the outer peripheral rubber flow rate in the outer peripheral flow passage 12o larger than the inner peripheral rubber flow rate in the inner peripheral flow passage 12i, the rotational speed of the screw 22 is made larger than that of the screw 32, For example, the capacity of the barrel 23 may be larger than that of the barrel 33. In addition to these, means that can provide a difference in the amount of rubber in each flow path that flows per unit time can be appropriately employed. Furthermore, it is effective to increase the fluidity by lowering the viscosity of the rubber passing through the outer peripheral flow path 12o than that of the rubber passing through the inner peripheral flow path 12i.

  In the present embodiment, the extruder 20 that supplies rubber to the outer peripheral side flow path 12o and the extruder 30 that supplies rubber to the inner peripheral side flow path 12i are configured separately. By appropriately controlling the operation, the balance of the rubber flow rate can be easily adjusted.

  The table 50 is configured to be rotatable in the R2 direction by a servo motor (not shown). The rotation speed of the servo motor is controlled by the control device 40. A band-shaped rubber S extruded through the base 15 is attached to the table 50. By sticking the belt-like rubber S on the rotating table 50, the belt-like rubber S is formed into an annular shape.

<Method of forming annular rubber member>
A method for molding an annular rubber member using the molding apparatus as described above will be described. In the method for forming an annular rubber member of the present invention, the rubbers are affixed in an annular shape onto the rotating table 50 while extruding rubber through the die 15 by the extruders 20 and 30, and the ends of the belt-like rubber S are bonded together. The annular rubber member is formed by joining the members.

  FIG. 5 is an explanatory view for explaining a molding process of the annular rubber member, and is a perspective view and a plan view. FIG. 6 is a schematic diagram showing how the ends of the belt-like rubber S are joined together.

  First, the base 15 is brought close to the table 50 from the vertical direction (FIGS. 5A and 6A), and the extrusion of the band-shaped rubber S is started. At this time, the table 50 has not yet rotated. After the extrusion of the rubber band S is started, the rotation of the table 50 is started, the amount of extrusion from the base 15 is increased to a predetermined amount, and the base 15 is gradually separated from the table 50 to a certain distance (FIG. 5B). ), FIGS. 6B to 6C). This process is referred to as a sticking start process P1.

  Next, the belt-like rubber S is stuck in an annular shape while maintaining the extrusion amount from the base 15 at a predetermined amount (FIGS. 5C and 6D to 6E). This process is referred to as a pasting process P2.

  Immediately before the end of the application of the belt-like rubber S, the amount of extrusion from the base 15 is reduced from a predetermined amount, and the ends of the belt-like rubber S are joined together (FIGS. 5 (d) and 6 (f)). This process is referred to as an end-of-bonding process P3.

  FIG. 7 shows an example of control of the number of rotations of the screws 22 and 32 of the extruders 20 and 30, where (a) shows the vicinity of the attaching start process P1, and (b) shows the vicinity of the attaching end process P3.

  In FIG. 7A, up to 3 seconds is the sticking start process P1, and after that is the sticking process P2. In the pasting step P2, the rotation speed of the screw 22 of the extruder 20 that determines the outer peripheral rubber flow rate is 10 rpm, and the rotation speed of the screw 32 of the extruder 30 that determines the inner peripheral rubber flow rate is 5 rpm. The side rubber flow rate is set larger than the inner peripheral side rubber flow rate. Thereby, more rubber | gum can be sent with respect to the outer peripheral part 11o of the opening 11, and the strip | belt-shaped rubber | gum S extruded as shown in FIG. 2 can be curved.

  In the attaching step P2, the flow rate ratio between the outer peripheral rubber flow rate and the inner peripheral rubber flow rate is 2: 1. On the other hand, in the sticking start process P1, the flow rate ratio between the outer peripheral rubber flow rate and the inner peripheral rubber flow rate is different from the flow rate ratio (2: 1) in the sticking process P2. Specifically, in the sticking start process P1, the rotational speed of the screw 32 of the extruder 30 is linearly increased from zero to 5 rpm, but the rotational speed of the screw 22 of the extruder 20 is increased from zero to 10 rpm. Increasing gradually. More specifically, the rotation speed of the screw 22 of the extruder 20 is increased from zero to 5 rpm in 0 to 2.5 seconds, and is increased from 5 rpm to 10 rpm in 2.5 to 3 seconds.

  In FIG. 7B, the pasting process P2 is performed up to 30 seconds, and the pasting process P3 is performed thereafter. The pasting process P2 is as described above. On the other hand, in the pasting end process P3, the flow rate ratio between the outer peripheral side rubber flow rate and the inner peripheral side rubber flow rate is made different from the flow rate ratio (2: 1) in the pasting step P2. Specifically, in the pasting end process P3, the rotational speed of the screw 32 of the extruder 30 is linearly decreased from 5 rpm to zero, but the rotational speed of the screw 22 of the extruder 20 is increased from 10 rpm to zero. Decreasing gradually. More specifically, the rotation speed of the screw 22 of the extruder 20 is decreased from 10 rpm to 5 rpm in 30 to 30.5 seconds, and is decreased from 5 rpm to zero in 30.5 to 33 seconds.

  FIG. 8 shows a plurality of cross-sectional shapes at the joined portion of the annular rubber member. The lower side of the cross-sectional view is the starting end S1 of the band-shaped rubber S, and the upper side is the terminal end S2 of the band-shaped rubber S. In the cross-sectional view, the target cross-sectional shape is indicated by a bold line. As shown in FIG. 8, the annular rubber member can have a desired cross-sectional shape by appropriately reducing the thickness of the outer peripheral portion even at the joint portion between the end portions.

  On the other hand, FIG. 9 shows a plurality of joining portions of annular rubber members formed in the sticking start process P1 and the sticking end process P3 in which the flow rate ratio between the outer peripheral rubber flow rate and the inner peripheral rubber flow rate is the same as that in the sticking step P2. The cross-sectional shape is shown for reference. The rotational speeds of the screws 22 and 32 in this reference example are shown in FIGS. 7 (a) and 7 (b). In this example, the thickness of the outer peripheral portion is greater than the target thickness at the joint portion. This is because the band-like rubber S pushed out from the base 15 in the sticking start process P1 is stuck on the table 50 so as to be rubbed at the tip of the base 15 so that the rubber flows to the outer peripheral portion with less resistance. It is because it is easy to become thick.

<Another embodiment>
(1) In the above-described embodiment, the outer peripheral rubber flow rate is increased to a predetermined amount in two stages in the pasting start process P1 and the pasting end process P3, but the present invention is not limited to this. That is, the outer peripheral rubber flow rate may be increased in three or more steps, or may be increased in a parabolic shape.

  (2) In the above-described embodiment, the base having the outer peripheral side flow path 12o for feeding rubber to the outer peripheral part of the opening 11 and the inner peripheral side flow path 12i for feeding rubber to the inner peripheral part of the opening 11 Although the base 15 is used, the base 15 may further include a central channel for feeding rubber into the central part of the opening 11. According to this, you may make it further provide the extruder which supplies rubber | gum to a center part flow path.

(3) In the above-described embodiment, the base 15 is moved and brought close to the table 50, but the table 50 may be moved and brought close to the base 15.

DESCRIPTION OF SYMBOLS 1 Bead part 1a Bead core 1b Bead filler 10 Bead member 11 Opening 11i Inner peripheral part 11o Outer peripheral part 12 Branching part 12i Inner peripheral side flow path 12o Outer peripheral side flow path 13 Merge part 15 Base 20 Extruder 30 Extruder 50 Table P1 Start of sticking Process P2 Application process P3 Application process S Band rubber

Claims (4)

A method of forming an annular rubber member, in which rubber is pasted in a ring shape while extruding rubber through a die on a rotating table, and the ends of the belt rubber are joined together,
The base is brought close to the table from the vertical direction, the extrusion of the rubber band is started, the extrusion amount from the base is increased to a predetermined amount, and the sticking is started to gradually separate the base from the table to a certain distance. Process,
A pasting step of pasting the rubber band in an annular shape while maintaining the extrusion amount from the base at a predetermined amount;
Immediately before the end of application of the band-shaped rubber, the amount of extrusion from the base is reduced from a predetermined amount, and the end-of-bonding step of joining the ends of the band-shaped rubber,
An opening having a shape corresponding to the cross-sectional shape of the belt-shaped rubber, an outer peripheral side channel for sending rubber to the outer peripheral part of the opening, and an inner peripheral side channel for sending rubber to the inner peripheral part of the opening Using the base you have,
The amount of extrusion from the die is increased or decreased by increasing or decreasing the outer peripheral side rubber flow rate in the outer peripheral side channel and the inner peripheral side rubber flow rate in the inner peripheral side channel, and the outer peripheral side rubber flow rate By curving the extruded rubber band by making it larger than the circumferential rubber flow rate ,
A method for molding an annular rubber member, characterized in that a flow rate ratio between the outer peripheral rubber flow rate and the inner peripheral rubber flow rate in the attaching start step and the attaching end step is different from the flow rate ratio in the attaching step . The annular rubber member has an outer peripheral portion thinner than an inner peripheral portion, and the ratio of the outer peripheral rubber flow rate to the inner peripheral rubber flow rate in the attaching start step and the attaching end step is determined in the attaching step. The method for molding an annular rubber member according to claim 1, wherein the ratio is smaller than the ratio. Said annular rubber member, method of forming an annular rubber member according to claim 1 or 2, characterized in that the outer peripheral portion is tapered cross-section triangular bead filler. It said annular rubber member, method of forming an annular rubber member according to claim 1 or 2, characterized in that a sidewall rubber.