JP2014088001A - Sector division position determination method for a tire vulcanizing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sector division position determination method for a tire vulcanizing mold capable of inhibiting the overflow amount of a rubber at the time of vulcanization and of determining, efficiently in high precision, a sector division position capable of abbreviating the correction work time of the mold.SOLUTION: Multiple three-dimensional pitch models 1a through 1d are prepared based on a three-dimensional pitch model 1a provided as a standard, whereas a three-dimensional whole-circumference tire model 2 is prepared by cyclically linking these multiple pitch models 1a through 1d, whereas, upon the designation, as a detection plane S, of a plane passing through the tire central axis CL orthogonally to the tire equator EL of this whole-circumference tire model 2, the detection plane S is mobilized, around a center coinciding with the tire central axis CL, over the entire circumference of the whole-circumference tire model 2 along the circumferential direction thereof for detecting groove cross-sectional areas A and groove cross-sectional deviation magnitudes D on the detection plane S at the respective positions along the circumferential direction, whereas the sector division position PL is determined based on the detected groove cross-sectional areas A and groove cross-sectional deviation magnitudes D.

Description

  The present invention relates to a method for determining a sector division position of a tire vulcanization mold. More specifically, the present invention relates to a sector division position that can reduce the amount of rubber overflow during vulcanization and reduce the mold correction processing time with high accuracy. The present invention relates to a method for determining a sector division position of a tire vulcanization mold.

  A sectional mold for vulcanizing a pneumatic tire has a plurality of sectors assembled in an annular shape. The abutment surface between adjacent sectors of the sector assembled in an annular shape is the sector division position. Groove forming projections for forming tire tread grooves are provided on the tread molding surface of the sector. When the mold is closed when the green tire is vulcanized, the groove forming projection comes into contact with the green tire before the portion without the groove forming projection on the tread molding surface. Therefore, if the position corresponding to the groove forming protrusion is set as the sector division position, the amount of overflow of the rubber at the sector division position during vulcanization tends to increase. Therefore, in order to suppress the overflow amount of rubber, it is preferable to set the sector division position to a position where the portion corresponding to the groove forming protrusion of the mold is minimized. When replaced with a tire, it is preferable to set the sector division position to a position where the portion corresponding to the groove formed in the tread is reduced as much as possible (a position where the groove cross-sectional area is reduced).

  By the way, in the tire design, a pitch model, which is a basic element of the tire, is created, and the entire tire circumference is designed using this pitch model. In general tires, in order to reduce tire noise caused by tread pattern noise, pitch models with different circumferential lengths of basic pitch models are mixed and connected in a ring shape, so-called pitch variations are adopted. The entire tire circumference is designed. Here, when pitch models having different circumferential lengths are connected to each other, in the inclined groove straddling the boundary between the two, a defect (groove section shift) in which the shapes of the groove sections do not match at the boundary occurs. It is necessary to modify the mold so that the portion where the groove cross-sectional deviation has occurred is eliminated. Therefore, the smaller the groove cross-sectional deviation, the more advantageous is the shortening of the mold correction processing time.

  Conventionally, for example, a system for determining a sector division position on a pitch arrangement diagram displaying a tread pattern around the entire tire has been proposed (see Patent Document 1). In this system, the division position is determined based on the number of contacts between the division line serving as the sector division position and the uneven edge of the tread surface, the adjacent distance of each contact, and the like. However, in this system, since plane data (two-dimensional data) is used, it is impossible to accurately grasp the groove sectional area and the groove sectional deviation amount at the sector division position. Therefore, it has been impossible to accurately and efficiently determine the sector division position capable of suppressing the amount of rubber overflow at the sector division position during vulcanization and reducing the mold correction processing time.

JP 2005-246931 A

  An object of the present invention is to provide a sector division position determination method for a tire vulcanization mold that can accurately and efficiently determine a sector division position capable of reducing the amount of rubber overflow during vulcanization and shortening the mold correction processing time. It is to provide.

  In order to achieve the above object, a method for determining a sector division position of a mold for tire vulcanization according to the present invention includes a step of creating a plurality of three-dimensional pitch models based on a three-dimensional pitch model as a basic element of the three-dimensional tire model, A step of creating a three-dimensional tire circumference model by connecting these multiple pitch models in a ring shape, and detecting the surface perpendicular to the tire equator of the created tire circumference model and passing through the tire central axis as a detection surface The surface of the tire is moved around the circumference of the tire circumference model around the tire center axis, and the cross-sectional area of the tire circumference model and the groove cross-sectional deviation of the tire circumference model at each of the moved circumferential positions are detected. And a step of determining a sector division position based on the detected groove cross-sectional area and groove cross-sectional deviation amount. To.

  According to the present invention, since a three-dimensional tire circumferential model is used, the groove sectional area and the groove sectional deviation amount on the detection surface that is orthogonal to the tire equator of the tire circumferential model and passes through the tire central axis are detected with extremely high accuracy. can do. The position of the detection surface can be easily moved in the circumferential direction around the tire central axis. The smaller the step pitch with respect to the circumferential movement of the detection surface, the more accurately the change (maximum value and minimum value) of the groove cross-sectional area and groove cross-sectional deviation can be grasped. Therefore, by determining the circumferential position at which the detected groove cross-sectional area and groove cross-sectional deviation is small as the sector division position, the amount of rubber overflow at the sector division position during vulcanization is suppressed, and at the sector division position. It is possible to accurately and efficiently determine the sector division position that can shorten the correction processing time of the mold.

  Here, for example, threshold values are respectively set for the groove cross-sectional area and the groove cross-sectional deviation amount, and the sector division is performed within a range in which the detected groove cross-sectional area and groove cross-sectional deviation amount are not more than the respective threshold values. Determine the position. This makes it possible to more easily determine an appropriate sector division position that satisfies the conditions. Then, if the threshold value to be set is programmed to be gradually reduced, an appropriate sector division position that satisfies the condition can be automatically determined.

  If at least one of the detected groove cross-sectional area and groove cross-sectional deviation amount does not fall below the threshold value, it is possible to shift to design change of the pitch model. Thereby, a flexible tire design can be performed without being bound by a specific tread pattern.

  Priorities are set for the two detection targets of the groove cross-sectional area and the groove cross-sectional deviation amount, and when the detected groove cross-sectional area and groove cross-sectional deviation amount are each equal to or less than the threshold value, detection with high priority is performed. The sector division position can also be determined so that the target detection amount becomes the minimum value. This makes it possible to determine a more ideal sector division position that satisfies the conditions.

It is a flowchart which illustrates the procedure of this invention. It is a top view which illustrates a basic pitch model. It is a side view which simplifies and illustrates a tire perimeter model. It is a perspective view of the tire perimeter model of FIG. It is a side view which illustrates typically a mold for tire vulcanization. It is explanatory drawing which illustrates the groove cross-sectional area of a tire perimeter model. It is explanatory drawing which illustrates the groove cross-sectional shift | offset | difference amount of a tire perimeter model. It is a graph which illustrates the detected groove cross-sectional area and groove cross-sectional deviation | shift amount.

  Hereinafter, a method for determining a sector division position of a tire vulcanization mold according to the present invention will be described based on the embodiments shown in the drawings. The present invention displays various three-dimensional data (three-dimensional CAD data) related to a pneumatic tire stored in a computer on a display, and inputs necessary data and instruction contents by input means such as a keyboard and a mouse. It is done by processing.

  In the present invention, as illustrated in FIG. 1, steps S1, S2, S3, and S4 described below are sequentially performed. However, there may be a step of performing contents other than steps S1 to S4. That is, the present invention includes at least steps S1 to S4, and when other steps are included, it is performed at an appropriate timing before and after each of steps S1, S2, S3, and S4.

  First, as step S1, a plurality of three-dimensional pitch models are created. At this time, a pre-designed three-dimensional pitch model 1a as illustrated in FIG. 2 as a basic element of the three-dimensional tire model is used. The pitch model 1 a has various three-dimensional data such as a circumferential groove 4 and an inclined groove 5 formed in the tire tread portion 3. A one-dot chain line in the figure indicates the tire equator EL. A groove extending in parallel with the tire equator EL is the circumferential groove 4, and a groove extending obliquely is the inclined groove 5.

  A plurality of three-dimensional pitch models are created based on the basic pitch model 1a. For example, a plurality of three-dimensional pitch models 1a, 1b, 1c, and 1d as illustrated in FIG. Each of the pitch models 1a to 1d is a pitch model in which the length in the tire circumferential direction is enlarged or reduced to be different, and the tread pattern is enlarged or reduced in the tire circumferential direction at the different ratio. In this embodiment, four types of pitch models 1a to 1d having different tire circumferential lengths are created. The types of pitch models to be created are determined based on tire specifications and the like, and are, for example, about 1 to 10 types.

  Next, as step S2, as illustrated in FIG. 3 and FIG. 4, the created plurality of pitch models 1a to 1d are connected in a ring shape to create a three-dimensional tire circumferential model 2. In order to reduce tire noise due to tread pattern noise, two or more types of pitch models 1a to 1d having different tire circumferential lengths are appropriately connected to form an annular shape. A so-called pitch variation is employed to create a three-dimensional tire circumference model 2. In addition, when not using a pitch variation with a special tire, a tire whole circumference model 2 is created by connecting a single pitch model in a plurality of rings.

  Next, as a step S3, the groove cross-sectional area A and the groove cross-sectional deviation amount D on the set detection surface S are detected for the created tire entire circumference model 2. The detection surface S is a surface that is orthogonal to the tire equator EL of the created tire circumferential model 2 and that passes through the tire central axis CL. The detection surface S is moved over the entire circumference in the circumferential direction of the tire circumferential model 2 around the tire central axis CL. Then, the groove cross-sectional area A and the groove cross-sectional deviation amount D of the tire entire circumference model 2 on the detection surface S at each moved circumferential position are detected. Details of the groove cross-sectional area A and the groove cross-sectional deviation amount D will be described later.

  The detection surface S is rotated and moved by a predetermined angle in the tire circumferential direction, for example. The predetermined rotation angle (that is, the step pitch with respect to the circumferential movement of the detection surface S) is set to about 0.5 ° to 1 °, for example.

  The detection surface S may be moved over the entire circumference in the circumferential direction of the tire circumferential model 2 around the tire central axis CL, and is not limited to the movement method described above. Further, the case where the position of the detection surface S is fixed and the tire circumferential model 2 is rotated about the tire central axis CL is also included in step S3 of the present invention. That is, in step S3 of the present invention, the detection surface S is moved relative to the tire circumferential model 2 in the tire circumferential direction with the tire central axis CL as the center.

  Next, as step S4, the sector division position PL is determined based on the detected groove cross-sectional area A and groove cross-sectional deviation amount D. As illustrated in FIG. 5, the tire vulcanization mold 6 (hereinafter, referred to as the mold 6) is configured by a plurality of sectors 7 assembled in an annular shape around the tire central axis CL. Groove forming projections for forming the circumferential grooves 4 and the inclined grooves 5 are projected on the inner peripheral surface of the sector 7, and each sector 7 moves in the radial direction so as to expand and contract the annular shape.

  Abutting surfaces of adjacent sectors 7 assembled in a ring form a sector division position PL, and a line segment indicating the sector division position PL is a line segment passing through the tire central axis CL. The number of sectors 7 constituting the mold 6 is determined in advance from the size of the tire and the like, and is approximately 8 or more. In the present invention, the necessary number of sector division positions PL are determined using the tire all-around model 2 so as to obtain a predetermined number of sectors 7.

  A tire cross section on the detection surface S at a certain circumferential position of the tire all-around model 2 can be expressed as illustrated in FIG. Here, the above-mentioned groove cross-sectional area A is the area A1, A2, A3, A4, A5, A6 defined by the groove provided in the tire tread portion 3 of the circumferential groove 4 or the inclined groove 5 and the tread surface. It is the total value of (the area of the shaded area in FIG. 6). Generally, since the groove cross-sectional area A on the detection surface S differs depending on the circumferential position, in step S3, the distribution of the groove cross-sectional area A on the entire circumference of the tire all-around model 2 can be grasped.

  As illustrated in FIG. 7, when the pitch models 1a and 1b having different circumferential lengths are connected to each other, in the inclined groove 5 straddling both, the shapes of the groove cross sections do not match at the boundary between the pitch models 1a and 1b. Defects (groove cross section deviation) occur. In FIG. 7, the cross section of the groove is indicated by the hatched portion. This groove cross-sectional deviation increases in the groove depth direction.

  In the portion where the groove cross-sectional deviation has occurred, it is necessary to correct the smoothness by removing the step by removing the mold 6 (sector 7) so as to eliminate the produced deviation. Therefore, the smaller the groove cross-sectional deviation amount D, the more advantageous is the shortening of the correction processing time of the mold 6 (sector 7). As the groove cross-sectional deviation amount D detected in the present invention, for example, the total value of the groove cross-sectional deviation areas D1 on the detection surface S (the area of the hatched portion in FIG. 7) is used. Alternatively, the maximum value of the groove section shift length D2 can be used. In step S <b> 3, the distribution of the groove cross-sectional deviation amount D on the entire circumference of the tire circumference model 2 can be grasped.

  In step S3, as illustrated in FIG. 8, the groove cross-sectional area A and the groove cross-sectional deviation amount D are detected. As the groove section deviation amount D in FIG. 8, a groove section deviation area D1 is used. The horizontal axis is the rotational movement angle of the detection surface S around the tire central axis CL. As illustrated in FIG. 8, the groove cross-sectional area A and the groove cross-sectional deviation amount D vary depending on the circumferential position on the entire circumference of the tire all-around model 2.

  In step S4, based on the detected groove cross-sectional area A and groove cross-sectional deviation D, the sector division position PL is determined at a circumferential position where the groove cross-sectional area A and groove cross-sectional deviation D are as small as possible. Since the number of sectors 7 is determined in advance, an area Z for determining the sector division position PL is determined based on a predetermined circumferential position of the tire all-around model 2 so as to match the predetermined number. Set as many as needed. For example, if the number of sectors 7 is 8, eight areas Z are set as illustrated in FIG. Then, the sector division position PL is determined at a circumferential position where the cross-sectional area A and the groove cross-sectional deviation D are as small as possible in each region Z.

  Since the present invention uses the three-dimensional tire circumference model 2 as described above, it is possible to detect the groove cross-sectional area A and the groove cross-sectional deviation amount D on the detection surface S with extremely high accuracy. In the conventional method using two-dimensional data, it is difficult to grasp the groove cross-sectional area A and the groove cross-sectional deviation amount D at each circumferential position with high accuracy as in the present invention.

  The detection surface S can be easily rotated in the circumferential direction around the tire central axis CL, and the pitch of the step in the circumferential direction can be set freely. The smaller the step pitch, the more accurately the change (maximum value or minimum value) at the circumferential position of the groove cross-sectional area A and the groove cross-sectional deviation D can be grasped. However, if the step pitch is too small, the time required to detect the groove cross-sectional area A and the groove cross-sectional deviation amount D increases. Therefore, based on the complexity of the tread pattern and the like, the step pitch of the detection surface S is set in consideration of the detection accuracy and detection time of the groove cross-sectional area A and the groove cross-sectional deviation D. A suitable step pitch is about 0.5 ° to 1 ° as described above.

  By determining the sector division position PL at a circumferential position where the detected groove cross-sectional area A is as small as possible, the amount of rubber overflow at the sector division position PL during vulcanization can be suppressed. Further, by determining the sector division position PL at a circumferential position where the detected groove cross-sectional deviation D is as small as possible, the correction processing time of the mold 6 (sector 7) at the sector division position PL can be shortened. In the present invention, it is possible to accurately and efficiently determine the sector division position PL that satisfies the two conditions of suppressing the rubber overflow amount and shortening the correction processing time of the mold 6 described above.

  For example, a threshold value is set for each of the groove cross-sectional area A and the groove cross-sectional deviation amount D. Then, the program is performed so that the sector division position PL is determined within a range where the detected groove cross-sectional area A and groove cross-sectional deviation amount D are equal to or less than the respective threshold values.

  This makes it possible to more easily determine an appropriate sector division position PL that satisfies the above two conditions. Here, if the threshold value to be set is programmed to be gradually reduced, an appropriate sector division position PL that satisfies the above two conditions can be automatically determined.

  If at least one of the detected groove cross-sectional area A and groove cross-sectional deviation D does not fall below a preset threshold value, it can be programmed to shift to a design change of the pitch model 1a (1a to 1d). In the case of shifting to the design change of the pitch model 1a (1a to 1d), for example, countermeasures such as an arrangement change or a shape change of the inclined groove 5 are taken. After the countermeasure, steps S1 to S4 are performed again to determine the sector division position PL. Thereby, a flexible tire design can be performed without being bound by a specific tread pattern.

  In the present invention, since there are two detection targets of the groove cross-sectional area A and the groove cross-sectional shift amount D, it is preferable to set the priority order among these detection targets. If each of the detected groove cross-sectional area A and groove cross-sectional deviation amount D is equal to or less than a preset threshold value, the sector division position PL is set so that the detection amount of the detection target having a high priority becomes the minimum value. decide.

  For example, when the groove cross-sectional area A is set to the first priority, if the groove cross-sectional area A and the groove cross-sectional deviation D are not more than the respective thresholds, the detected groove cross-sectional area A is The sector division position PL is determined at the circumferential position where the minimum value is obtained. Alternatively, the groove section deviation amount D can be set to the first priority. This makes it possible to determine a more ideal sector division position PL that satisfies the above two conditions.

1a, 1b, 1c, 1d Pitch model 2 Tire whole circumference model 3 Tire tread part 4 Circumferential groove 5 Inclined groove 6 Mold 7 Sector CL Tire center axis EL Tire equator PL Sector division position A Groove cross-sectional area D Groove cross-sectional deviation D1 Groove cross-sectional deviation area D2 Groove cross-sectional deviation length

Claims (4)

  A step of creating a plurality of three-dimensional pitch models based on a three-dimensional pitch model that is a basic element of the three-dimensional tire model, and a step of creating a three-dimensional tire circumference model by connecting the plurality of pitch models in a ring shape The detection surface is a surface that is orthogonal to the tire equator of the created tire all-around model and passes through the tire center axis, and this detection surface is centered on the tire center axis over the entire circumference of the tire all-around model. A step of detecting the groove cross-sectional area and the groove cross-sectional deviation amount of the tire whole circumference model on the detection surface at each of the moved circumferential positions, and the sector based on the detected groove cross-sectional area and groove cross-sectional deviation amount Determining a division position, and a sector division position determination method for a tire vulcanization mold.   A threshold value is set for each of the groove cross-sectional area and the groove cross-sectional deviation amount, and the sector division position is determined within a range in which the detected groove cross-sectional area and groove cross-sectional deviation amount are equal to or less than the respective threshold values. Item 2. A method for determining a sector division position of a tire vulcanization mold according to Item 1.   The method of determining a sector division position of a tire vulcanization mold according to claim 2, wherein when at least one of the detected groove cross-sectional area and groove cross-sectional deviation amount does not fall below the threshold value, the process shifts to a design change of the pitch model.   Priorities are set for the two detection targets of the groove cross-sectional area and the groove cross-sectional deviation amount, and when the detected groove cross-sectional area and groove cross-sectional deviation amount are each equal to or less than the threshold value, detection with high priority is performed. The sector division position determination method of the tire vulcanization mold according to claim 2 or 3, wherein the sector division position is determined so that a target detection amount becomes a minimum value.

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