JP2008137309A - Method for forming sidewall mark - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form easily a clear mark on the sidewall 34 of a tire 30. <P>SOLUTION: The grinding apparatus 2 is equipped with the support pillar 4, top plate 6, laser displacement gauge 8, screw shaft 10, first motor 12, ball nut 14, arm 16, second motor 18, grindstone 20, trestle 22, rotary core 24, drum 26 and control part 28. By the revolution of the first motor 12 the screw shaft 10 is revolved. By the rotation of the screw shaft 10 the ball nut 14 ascends or descends and with this ball nut 14 the grindstone 20 ascends or descends. The laser displacement gauge 8 measures the distance between this laser displacement gauge 8 and the sidewall 34. When the grindstone 20 is at the set position, a first grinding is performed. The amount of the grinding is calculated by the laser displacement gauge 8 and the control part 28. When the amount of the grinding is insufficient, the grindstone 20 descends to conduct an additional grind. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for forming a mark having a color different from that of a periphery on a tire sidewall.

  A typical tire is black. This black color is caused by carbon black dispersed in the rubber composition. There are tires with white marks on the sidewalls. This mark is made of a rubber composition that does not contain carbon black and contains a white filler such as silica. Examples of the mark include a line and a logo.

  In the preforming of a tire having a white mark, a white rubber composition is used as a base for a part of the sidewall. This rubber composition is covered with a black rubber composition as a masking layer. The green tire obtained by the preforming is put into a mold, and is pressurized and heated. A concave portion having a predetermined shape is present in a portion corresponding to the sidewall in the cavity surface of the mold. The rubber composition flows into the recess by pressurization and heating. The rubber is crosslinked by heating, and a tire is obtained. The rubber composition that has flowed into the concave portion forms a convex portion on the sidewall. In this convex part, a white base and a black masking layer are laminated. By grinding the upper surface of the convex portion, the masking layer on the upper surface is removed, and the base is exposed. Portions other than the convex portions remain covered with the masking layer. By grinding, a mark whose contour is substantially equal to the contour of the convex portion is formed.

  A grinding device is used to form the marks. This grinding apparatus includes a grindstone and means for raising and lowering the grindstone with respect to the sidewall. The grindstone descends to the set position and comes into contact with the convex portion. As the grindstone rotates, the upper surface of the convex portion is ground. An example of such a grinding apparatus is disclosed in Japanese Patent Laid-Open No. 2001-287162.

If the grinding amount of the masking layer is insufficient, the base layer is not completely exposed. On the other hand, excessive grinding of the masking layer leads to poor quality of the sidewall. Subtle adjustment of the grinding amount is necessary. In other words, a delicate setting of the distance between the grindstone and the sidewall is necessary. The suitability of the grinding amount is determined visually.
JP 2001-287162 A

  Since the tire is mainly made of rubber, it expands or contracts depending on the temperature. The height of the convex portion varies depending on the temperature. In a tire with a low convex part, insufficient grinding tends to occur. In this case, the convex portion is further ground manually. Manual grinding is inefficient. In a tire with a high convex part, excessive cutting tends to occur. Excessively cut tires are discarded. The loss due to excessive cutting is large.

  An object of the present invention is that a clear mark is easily formed on a sidewall of a tire.

The method for forming a sidewall mark according to the present invention includes:
(A) A tire having a convex portion protruding from the reference surface of the sidewall, the convex portion comprising a base and a masking layer covering the base, and the color of the masking layer being different from the color of the convex portion. The resulting process,
(B) a step in which the upper surface of the convex portion is ground by a grinding tool at a set position;
(C) A step of measuring the grinding amount of the convex portion and (D) a step of determining whether or not further grinding is performed by comparing the grinding amount with a target value.

Preferably, this forming method comprises:
(E) a step in which the upper surface of the convex portion is further ground by the grinding tool at the set position when it is determined that further grinding is necessary in the step (D),
(F) including a step of measuring the total grinding amount in the steps (B) and (E), and (G) determining whether or not further grinding is performed by comparing the total grinding amount with a target value. .

Preferably, this forming method comprises:
(H) When it is determined in the step (G) that further grinding is necessary, the grinding tool moves from the set position and approaches the reference surface, and (I) the upper surface of the convex portion is further ground by this grinding tool. Including a process.

According to another aspect, the method for forming a sidewall mark according to the present invention includes:
(A) A tire having a convex portion protruding from the reference surface of the sidewall, the convex portion comprising a base and a masking layer covering the base, and the color of the masking layer being different from the color of the convex portion. The resulting process,
(B) a step of measuring an initial step between the reference surface and the convex portion;
(C) a step of grinding the upper surface of the convex portion with a grinding tool at a set position;
(D) a step in which a step after grinding between the reference surface and the convex portion is measured;
(E) includes a step of calculating a grinding amount based on the initial step and the grinding step, and (f) a step of determining whether or not further grinding is performed by comparing the grinding amount with a target value.

  In the forming method according to the present invention, the convex portion is ground with an appropriate amount. A sharp mark is formed by this grinding. This forming method does not require manual grinding. In this forming method, excessive grinding is difficult to occur.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 is a front view showing an example of a grinding apparatus 2 used in the forming method according to the present invention. The apparatus 2 includes a support 4, a top plate 6, a laser displacement meter 8, a screw shaft 10, a first motor 12, a ball nut 14, an arm 16, a second motor 18, a grindstone 20, a mount 22, a rotary core 24, and a drum 26. And a control unit 28. FIG. 1 also shows a tire 30. The tire 30 includes a tread 32 and a sidewall 34. In FIG. 1, the sidewall 34 extends in the horizontal direction.

  The support column 4 stands up from the base 36 and extends in the vertical direction. One end of the top plate 6 is fixed to the column 4. The top plate 6 extends in the horizontal direction. The laser displacement meter 8 is suspended from the top plate 6. The tip of this laser displacement system faces downward. The screw shaft 10 extends in the vertical direction. A male screw is threaded on the outer peripheral surface of the screw shaft 10. The screw shaft 10 is connected to the first motor 12. The first motor 12 is a servo type. A female screw is threaded on the inner peripheral surface of the ball nut 14. The ball nut 14 meshes with the screw shaft 10. One end of the arm 16 is fixed to the ball nut 14. A second motor 18 is attached to the arm 16. Further, a grindstone 20 is pivotally supported on the arm 16. The grindstone 20 is connected to the second motor 18 by a pair of pulleys 38 and a belt 40. The gantry 22 is placed on a base 36. A rotating core 24 extends from the gantry 22. The rotary core 24 can rotate freely with respect to the gantry 22. A tire 30 is attached to the rotating core 24. The drum 26 is in contact with the tread 32. The drum 26 is rotated by driving means (not shown). The controller 28 is connected to the laser displacement meter 8, the first motor 12, and the drum 26.

  As the first motor 12 rotates forward and backward, the screw shaft 10 rotates forward and backward. As the screw shaft 10 rotates forward and backward, the ball nut 14 descends and rises. As the ball nut 14 moves up and down, the arm 16 and the grindstone 20 move up and down. The first motor 12 can control the distance between the grindstone 20 and the sidewall 34. Instead of the ball nut-screw mechanism, a rack and pinion mechanism, a chain mechanism, or the like may be employed.

  The grindstone 20 is rotated by the rotation of the second motor 18. The side wall 34 can be ground by the grindstone 20. The tire 30 is rotated by the rotation of the drum 26. As the tire 30 rotates, the relative position of the grindstone 20 with respect to the tire 30 in the circumferential direction of the tire 30 moves. A laser is emitted from the laser displacement meter 8. The laser travels in the vertical direction. The laser is reflected by the sidewall 34. This reflected light is received by the laser displacement meter 8. The laser displacement meter 8 can measure the distance between the laser displacement meter 8 and the sidewall 34. Measuring means other than the laser displacement meter 8 may be used. A grinding tool other than the grindstone 20 may be used.

  FIG. 2 is an enlarged cross-sectional view showing a part of the sidewall 34 to be ground by the apparatus 2 of FIG. The sidewall 34 includes a reference surface 42 and a convex portion 44. The convex portion 44 protrudes from the reference surface 42. The sidewall 34 includes a base 46 and a masking layer 48. The base 46 contains silica as a reinforcing agent. The base 46 does not contain carbon black. The color of the base 46 is white. The masking layer 48 contains carbon black as a reinforcing agent. The color of the masking layer 48 is black. The masking layer 48 covers the base 46. The base 46 is not exposed. This sidewall 34 is entirely black. A plurality of convex portions 44 are scattered along the circumferential direction of the sidewall 34.

  FIG. 3 is a flowchart showing a mark forming method using the apparatus 2 of FIG. In this method, the tire 30 is first manufactured (STEP 1). The sidewall 34 of the tire 30 includes a convex portion 44 shown in FIG. The tire 30 is set in the device 2 (STEP 2). Specifically, the tire 30 is attached to the rotating core 24.

  The distance of the tire 30 to the sidewall 34 is measured by the laser displacement meter 8 (STEP 3). Specifically, the laser displacement meter 8 measures a distance X0 (see FIG. 2) to the reference surface 42 and a distance Y0 to the convex portion 44. The measured data is transmitted to the control unit 28. The control unit 28 subtracts the distance Y0 from the distance X0 to calculate the initial step Z0 between the reference surface 42 and the convex portion 44 (STEP 4).

  The first motor 12 rotates forward and lowers the grindstone 20 (STEP 5). The moving distance of the grindstone 20 is indicated by an arrow M0 in FIG. This distance M0 is a value set in advance for each type of tire 30. The grindstone 20 after movement is indicated by a two-dot chain line in FIG. The grindstone 20 is in the set position. The lower end of the grindstone 20 is located above the reference surface 42 and located below the upper surface of the convex portion 44.

  When the second motor 18 rotates the grindstone 20, the upper surface of the convex portion 44 is ground by the grindstone 20 (STEP 6). At the same time, the drum 26 rotates and the tire 30 rotates. Due to the rotation of the tire 30, all the convex portions 44 scattered along the circumferential direction of the sidewall 34 are ground.

  After grinding, the laser displacement meter 8 measures the distance X1 to the reference surface 42 and the distance Y1 to the convex portion 44 (STEP 7). The measured data is transmitted to the control unit 28. The controller 28 subtracts the distance Y1 from the distance X1 and calculates a post-grinding step Z1 between the reference surface 42 and the convex portion 44 (STEP 8). The control unit 28 further subtracts the post-grinding step Z1 from the initial step Z0 to calculate the grinding amount (Z0-Z1) (STEP 9). In this calculation method, even if the tire expands or contracts due to a temperature change between the measurement before grinding (STEP 3) and the measurement after grinding (STEP 7), the influence of the expansion and contraction is eliminated. .

  The controller 28 compares the grinding amount (Z0-Z1) with the target value (STEP 10). This target value is a value determined in advance according to the type of tire 30. When the grinding amount (Z0-Z1) matches the target value, a white mark is clearly formed on the sidewall 34. Since the height of the convex portion 44 varies, the grinding amount (Z0-Z1) may not match the target value. When the grinding amount (Z0-Z1) matches the target value, and when the grinding amount exceeds the target value, the tire 30 is removed from the device 2.

  When the grinding amount (Z0-Z1) is smaller than the target value, the second grinding is performed on the upper surface of the convex portion 44 (STEP 11). Even in the second grinding, the grindstone 20 is rotated by the second motor 18, and the tire 30 is rotated by the drum 26. The position of the grindstone 20 in the second grinding is the same as that in the first grinding. That is, the grindstone 20 is at the set position.

  After the second grinding, the laser displacement meter 8 measures the distance X2 to the reference surface 42 and the distance Y2 to the convex portion 44 (STEP 12). The measured data is transmitted to the control unit 28. The control unit 28 subtracts the distance Y2 from the distance X2, and calculates a post-grinding step Z2 between the reference surface 42 and the convex portion 44 (STEP 13). The control unit 28 further subtracts the post-grinding step Z2 from the initial step Z0 to calculate the total grinding amount (Z0-Z2) (STEP 14). In this calculation method, even if the tire expands or contracts due to a temperature change between the measurement before grinding (STEP 3) and the measurement after grinding (STEP 12), the influence of the expansion and contraction is eliminated. .

  The controller 28 compares the total grinding amount (Z0-Z2) with the target value (STEP 15). When the total grinding amount (Z0-Z2) matches the target value and when the total grinding amount (Z0-Z2) exceeds the target value, the tire 30 is removed from the device 2.

  When the total grinding amount (Z0-Z2) is smaller than the target value, the control unit 28 calculates a difference M1 between the target value and the total grinding amount (Z0-Z2) (STEP 16). The control unit 28 controls the first motor 12 to further lower the grindstone 20 (STEP 17). The grindstone 20 approaches the reference surface 42. The moving distance of the grindstone 20 is M1. The total movement distance of the grindstone 20 is (M + M1). With this grindstone 20, the upper surface of the convex portion 44 is ground for the third time (STEP 18).

  By these grinding, the masking layer 48 of the convex portion 44 is removed. A white base 46 is exposed on the upper surface of the convex portion 44. On the other hand, the periphery of the convex portion 44 is covered with a black masking layer 48. The base 46 constitutes a white mark.

  If excessive cutting is performed, the sidewall 34 is damaged. From the viewpoint of preventing damage, the position (set position) of the grindstone 20 when the first grinding is performed is determined in consideration of the safety factor. Therefore, the grinding amount by the grindstone 20 at the set position is often less than the target value. In the method according to the present invention, even if the cutting amount falls below the target value, the second and third grindings are automatically performed. This formation method is excellent in efficiency.

  By the mark forming method according to the present invention, a logo mark such as a brand can be formed on the sidewall. By this forming method, a white circular line can also be formed. By this forming method, marks of colors other than white can also be formed.

FIG. 1 is a front view showing an example of a grinding apparatus used in the forming method according to the present invention. FIG. 2 is an enlarged cross-sectional view showing a part of a sidewall ground by the apparatus of FIG. FIG. 3 is a flowchart showing a mark forming method using the apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Grinding device 8 ... Laser displacement meter 10 ... Screw shaft 12 ... First motor 14 ... Ball nut 18 ... Second motor 20 ... Grinding wheel 26 ... Drum 28 ... Control part 30 ... Tire 32 ... Tread 34 ... Side wall 42 ... Reference plane 44 ... Convex part 46 ... Base 48 ... Masking layer

Claims (4)

(A) A tire having a convex portion protruding from the reference surface of the sidewall, the convex portion comprising a base and a masking layer covering the base, and the color of the masking layer being different from the color of the convex portion. The resulting process,
(B) a step in which the upper surface of the convex portion is ground by a grinding tool at a set position;
(C) A step of measuring the grinding amount of the convex part and (D) a method of forming a sidewall mark including a step of determining whether or not further grinding is performed by comparing the grinding amount with a target value. (E) a step in which the upper surface of the convex portion is further ground by the grinding tool at the set position when it is determined that further grinding is necessary in the step (D),
(F) including a step of measuring the total grinding amount in the steps (B) and (E), and (G) determining whether or not further grinding is performed by comparing the total grinding amount with a target value. The forming method according to claim 1. (H) When it is determined in the step (G) that further grinding is necessary, the grinding tool moves from the set position and approaches the reference surface, and (I) the upper surface of the convex portion is further ground by this grinding tool. The forming method according to claim 2, comprising a step of: (A) A tire having a convex portion protruding from the reference surface of the sidewall, the convex portion comprising a base and a masking layer covering the base, and the color of the masking layer being different from the color of the convex portion. The resulting process,
(B) a step of measuring an initial step between the reference surface and the convex portion;
(C) a step of grinding the upper surface of the convex portion with a grinding tool at a set position;
(D) a step in which a step after grinding between the reference surface and the convex portion is measured;
(E) a sidewall including a step of calculating a grinding amount based on the initial step and the grinding step, and (f) a step of determining whether or not further grinding is performed by comparing the grinding amount with a target value. Mark formation method.

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