JPH09239866A - Method for discriminating retreaded tire and manufacture of retreaded tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a working time for measuring a tire and utilize a used tire effectively. SOLUTION: Before buffing the tread 10 of a used tire 1, the surface of the tread 10 and sidewall parts 7, 7a are measured with noncontact sensors 40, 50A, 50B. The surface of the tread 10 is divided in the circumferential direction of the tire, the minimum distance among distances from the rotational center of the tire to the surface of the divided range is made a groove bottom value, and the true outside diameter of the groove bottom is obtained by doubling the average groove bottom value. The outside diameter dimension D of a buff adjusting surface 6 is calculated on the basis of the true outside diameter of the groove bottom, and the dimension of the maximum width W3 is calculated from the measured values of the outer surface displacement of the sidewall parts 7, 7a and compared with respective standard dimensions corresponding to the above-mentioned dimensions of a mold using a base tire 9 obtained from the used tire 10 to judge whether the used tire 1 is suitable for vulcanization molding by the mold or not.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the field of manufacturing retreaded tires by a mold vulcanization method.

[0002]

2. Description of the Related Art Conventionally, in a mold vulcanization type retread tire manufacturing method called remolding retreading method, first, the outer circumference of a used tire is measured with a tape measure, and the outer diameter of the used tire is converted from the outer peripheral dimension. The groove depth is measured with a depth gauge at 3 to 5 points on the circumference, an average value is obtained, and the average value of the groove depth is subtracted from the above outer diameter value to obtain the dimension of the outer diameter of the buff adjusting surface.

Next, as shown in FIG. 4 showing a cross section in the width direction of a used tire having a belt layer, the used tire 2
The distance W ₀ between the bead heels 26 and 26a of ₀ is kept at a regular predetermined distance, and the tread portion 21 is buffed to be removed by cutting while rotating, and the buff adjusting surface 22 shown by the dotted line is finished to obtain the base tire 23. .

Further, the maximum width W ₁ of the base tire 23 is measured with a large caliper or the like to obtain its dimension. The buff adjusting surface 22 has a maximum width W _{1 of the} sidewall portions 28, 28a.
The dimension of the maximum width W ₁ is the same for both the used tire 20 and the base tire 23 obtained from it, since it does not come to a low position.

In this way, after the outer diameter D ₁ and the maximum width W _{1 of} the base tire 23 are obtained, these dimensions and the predetermined unvulcanized rubber are attached to the base tire 23. Comparing the raw tire on which the tread with unprocessed pattern grooves is wound with the corresponding reference dimension of the mold for vulcanization, the suitability of the base tire 23 and the compatible mold type are the tire outer diameter. Was determining which of the three types of LAEGE (large), MIDIUM (medium) and SMALL (small) was suitable.

Here, a raw tire is referred to as a state in which an unvulcanized rubber tread is attached to a base tire, and a product tire can be obtained by vulcanizing and molding this.

As described above, conventionally, after the buff adjusting surface 22 is completed and the base tire 23 is actually obtained, each part is measured to determine whether or not it is suitable for vulcanization molding by a mold.

Therefore, the conventional technique has the following problems.

[0009]

After the buff adjusting surface 22 is completed and the base tire 23 is obtained, when it is determined that the base tire 23 is not suitable for vulcanization molding by the mold, the base tire 23 can no longer be used. As a result, scrap processing is performed, and used tires 20 which are valuable for manufacturing retreaded tires are wasted. In this case, all the man-hours required to form the base tire 23 are wasted, resulting in a great loss.

Further, when the design value of the tire to be rehabilitated is known, if the dimension of the outer diameter D ₀ of the upper surface of the outermost belt layer 25 of the belt 24 is predicted from the design value and buffing is performed, an actual product tire is obtained. May vary and the actual outer diameter D ₀ may be larger than the design value, and the buff adjustment surface 22 reaches the outermost belt layer 25, and the used tire 20
May be scrapped.

Therefore, in order to prevent this, during the buffing, the rotation of the used tire 20 is stopped, and the outer peripheral surface of the buffed is cut into a mortar shape, and the belt 2 is actually cut.
If buffing is performed while checking the depth to the upper surface of No. 5, it takes a long time and there is a problem that productivity is largely alienated.

The method for manufacturing a retreaded tire can be roughly divided into two methods, a mold vulcanization molding method and a precure method described above. In the precure method, a new tread to be attached to the outer periphery of a base tire is used. A pattern groove is already formed by vulcanization molding on the outer peripheral surface of the.

The precure method is referred to as an envelope for a green tire in which the precure tread is wound around the outer periphery of the base tire in order to firmly vulcanize and bond the precure tread having the pattern groove to the outer periphery of the base tire. This is a method of vulcanizing by covering with a flexible bag and heating in a vulcanizing can, which is different from the method of newly vulcanizing and molding the pattern groove with a mold, and therefore, the sidewall portions 28, 28a described above.
Shape, the maximum width W ₁ of the base tire 23, and the buff adjustment surface 22
Has a large tolerance for variations in the outer diameter D ₁ of
There is almost no possibility that retreaded tires cannot be manufactured by the precure method because these dimensions are not suitable.

Therefore, in the case of the precure method, it is not necessary to know the dimension as described above before buffing the used tire 20 to form the buff adjusting surface.

Moreover, when the precure tread is adhered by the precure method, as shown in FIG. 5, the buff adjusting surface 29 shown by the dotted line of the used tire 20 has a substantially single CR (crown radius) in the width direction. It has a shape.

Therefore, before the used tire 20 is buffed and adjusted to form the base tire 23 used in the mold vulcanization molding method, the required dimension is measured to determine whether or not it is suitable for the mold vulcanization molding method. If it can be determined, even if it is determined to be unsuitable for the mold vulcanization molding method, the used tire 20 that has been conventionally scrapped is diverted to the precure method, and a substantially single CR buff adjusting surface in the width direction. By using the base tire 30 formed with 29, the used tire 20 can be effectively used.

However, when it is determined that the buff adjusting surface 22 cannot be used in the mold vulcanization molding method after the buff adjusting surface 22 is formed as described above, the buff adjusting surface 22 is ground up to the shoulders 27 and 27a. With the precure method, too much cutting is done,
This stand tire 23 can no longer be converted to the precure method and is discarded.

Therefore, the object of the present invention is to measure the required dimension and determine whether or not it is suitable for the mold vulcanization molding method before buffing a used tire to form a base tire. It is to provide a technique for effectively using a used tire.

[0019]

According to a first aspect of the present invention, an unvulcanized rubber tread is attached to a buff surface of a base tire prepared by buffing a tread portion of a used tire having a belt layer. Before manufacturing the retreaded tire by vulcanizing and molding with a mold after attaching it, before buffing the tread part of the used tire, use a non-contact sensor in advance to at least the outer diameter of the bottom of the tread groove and the tire on the outer surface of the sidewall part. A method for discriminating a retreaded tire for measuring the maximum width and determining the applicability to a mold, in which the circumference of a used tire is divided into at least 10 or more in the tire circumferential direction, and the tire surface in the divided range The minimum dimension from the tire rotation center is regarded as the groove bottom value, and the value obtained by doubling the average groove bottom value obtained based on the groove bottom values in the entire range is the true outer diameter of the tread groove bottom. age The outer diameter dimension of the outermost belt upper surface of the belt layer and the outer diameter dimension of the buff adjusting surface are calculated from the true outer diameter of the tread groove bottom portion, and the outer diameter dimension of the outermost layer belt upper surface and the sidewall are calculated. By comparing the maximum width dimension of the tire on the outer surface with the respective standard dimensions corresponding to the dimension of the mold to be vulcanized and molded using the base tire obtained from this used tire, this use It is characterized by determining whether or not the used tire is suitable for vulcanization molding by a mold.

Next, the operation of the method for discriminating retreaded tires according to claim 1 will be described. First, a used tire having a belt layer is mounted on a tire rotation device or the like and rotated, and a size of the tire outer peripheral surface from the tire rotation center is set to 1 by using a reflective non-contact sensor such as a laser.
Measure around the lap.

The circumference of the used tire is divided into at least 10 or more in the tire circumferential direction, and the minimum dimension from the tire rotation center of the tire surface in each divided range is regarded as the groove bottom value.

Next, the value obtained by doubling the average value obtained on the basis of the groove bottom values in all ranges is taken as the true outer diameter of the tread groove bottom.

From the true outer diameter of the bottom of the tread groove, the outer diameter dimension of the outermost belt upper surface of the belt layer and the outer diameter dimension of the buff adjusting surface are calculated, and the calculated outer diameter dimension of the outermost layer belt is calculated. This used tire is suitable for vulcanization molding with a mold by comparing with the reference dimension corresponding to the outer diameter dimension of the mold to be vulcanized and molded using the base tire obtained from this used tire. Determine whether or not

Here, the skid base gauge, which is the distance between the bottom of the tread groove and the upper surface of the outermost layer belt, is determined by the type of tire. For example, in the case of a truck / bus tire, it is usually 4 to 6 mm.

The position of the buff adjusting surface for buffing the tread portion of the used tire and cutting off the tread portion is a substantially intermediate position between the bottom portion of the tread groove and the upper surface of the outermost belt. Therefore, the outer diameter of the buff adjusting surface is the outer diameter of the upper surface of the outermost layer belt plus 4 to 6 mm.

That is, if the true outer diameter of the bottom of the tread groove is known, the outer diameter of the outermost belt upper surface is calculated by subtracting twice the skid base gauge from the true outer diameter. Can be done.

Then, 4 to 6 are provided on the upper surface of the outermost belt.
The position where 2 to 3 mm, which is about ½ of mm, is added is the position to be buffed on this used tire to be the buff adjustment surface, and the outer diameter of the outermost belt is 2 to 3 mm. 2 times, that is, 4 to 6 mm, the outer diameter dimension of the buff adjusting surface of this used tire is obtained.

Next, the outer diameter dimension of the upper surface of the outermost layer belt thus obtained and the raw tire when a predetermined tread is wound around the base tire obtained from this used tire should be vulcanized and molded. By comparing with the reference dimension corresponding to the outer diameter dimension of the die for it, if it is within the standard, it is possible to perform vulcanization molding with the die, and if it is out of the standard, it may be judged as unsuitable. become able to do.

According to the second aspect of the invention, the tread of the unvulcanized rubber is attached to the buff surface of the base tire prepared by buffing the tread portion of the used tire having the belt layer, and then the die is used to mold the tread. When manufacturing a retreaded tire by vulcanization molding, before buffing the tread portion of the used tire, measure at least the outer diameter of the tread groove bottom portion and the tire maximum width of the sidewall portion outer surface in advance using a non-contact sensor. A method for manufacturing a retreaded tire, which comprises retreading a tire after determining its applicability to a mold, wherein the circumference of a used tire is divided into at least 10 or more in the tire circumferential direction,
The minimum dimension from the tire rotation center on the tire surface in the divided range is regarded as the groove bottom value, and the value obtained by doubling the average groove bottom value obtained based on the groove bottom values in all the ranges is used as the tread groove. With the true outer diameter of the bottom portion, the outer diameter dimension of the outermost layer belt upper surface of the belt layer and the outer diameter dimension of the buff adjustment surface are calculated from the true outer diameter of the tread groove bottom portion, and the outermost layer belt upper surface Outer diameter dimension and tire maximum width dimension on the outer surface of the sidewall portion, and respective reference dimensions corresponding to the dimension of the mold to be vulcanized and molded using the base tire obtained from this used tire, By comparing, it is determined whether or not this used tire is suitable for vulcanization molding by a mold, and the tread portion of the used tire that is determined to be suitable for vulcanization molding by a mold by the judgment. The calculated buff adjustment To form a base tire by buffing based on the outer diameter dimension of the base tire, and then stick a tread of unvulcanized rubber on the buff surface of the base tire and then vulcanize and mold with a mold to manufacture a retreaded tire. Is characterized by.

Next, the operation of the method for manufacturing a retreaded tire according to claim 2 will be described. First, a used tire having a belt layer is mounted on a tire rotation device or the like and rotated, and a size of the tire outer peripheral surface from the tire rotation center is set to 1 by using a reflective non-contact sensor such as a laser.
Measure around the lap.

The circumference of the used tire is divided into at least 10 or more in the tire circumferential direction, and the minimum dimension from the tire rotation center of the tire surface in each divided range is regarded as the groove bottom value.

Next, a value obtained by doubling the average value obtained based on the groove bottom values in all ranges is taken as the true outer diameter of the tread groove bottom portion.

From the true outer diameter of the bottom of the tread groove, the outer diameter dimension of the outermost belt upper surface of the belt layer and the outer diameter dimension of the buff adjusting surface are calculated, and the calculated outer diameter dimension of the outermost layer belt is calculated. This used tire is suitable for vulcanization molding with a mold by comparing with the reference dimension corresponding to the outer diameter dimension of the mold to be vulcanized and molded using the base tire obtained from this used tire. Determine whether or not

The skid base gauge, which is the distance between the bottom of the tread groove and the upper surface of the outermost belt, is determined depending on the type of tire, and is usually 4 to 6 mm for truck and bus tires.

The position of the buff adjusting surface where the tread portion of the used tire is buffed and the tread portion is cut off is approximately the middle position between the bottom portion of the tread groove and the upper surface of the outermost belt. Therefore, the outer diameter of the buff adjusting surface is the outer diameter of the upper surface of the outermost layer belt plus 4 to 6 mm.

That is, if the true outer diameter dimension of the bottom of the tread groove is known, the outer diameter dimension of the outermost belt upper surface is calculated by subtracting twice the skid base gauge from the true outer diameter dimension. Can be done.

Then, 4 to 6 are formed on the upper surface of the outermost belt.
The position where 2 to 3 mm, which is about ½ of mm, is added is the position to be buffed on this used tire to be the buff adjustment surface, and the outer diameter of the outermost belt is 2 to 3 mm. 2 times, that is, 4 to 6 mm, the outer diameter dimension of the buff adjusting surface of this used tire is obtained.

Next, the outer diameter of the outermost surface of the outermost layer belt thus obtained and the raw tire when a predetermined tread is wound around the base tire obtained from this used tire should be vulcanized and molded. By comparing with the reference dimension corresponding to the outer diameter dimension of the die for it, if it is within the standard, it is possible to perform vulcanization molding with the die, and if it is out of the standard, it may be judged as unsuitable. become able to do.

Next, a tread of unvulcanized rubber was attached to the buff surface of the base tire, which was adjusted by buffing the tread portion of the used tire that was determined to be suitable for vulcanization molding using a mold. A retreaded tire can be manufactured by vulcanizing and molding the above.

The invention described in claim 3 is the same as that of claim 2.
In the method for manufacturing a retreaded tire according to item 1, when the tread groove is a zigzag pattern extending along the tire circumferential direction, the number of divisions in the tire circumferential direction on the tire circumference is the minimum unit of the tire that forms the zigzag pattern. It is characterized in that the above-mentioned minimum dimension is obtained by dividing the number of minutes or less and measuring the dimension from the center of tire rotation to the groove bottom at the axial center of the zigzag pattern.

Next, the operation of the method for manufacturing a retreaded tire according to claim 3 will be described. When the tread groove has a zigzag pattern extending along the tire circumferential direction, the dimension from the tire rotation center to the groove bottom at the tire axial center position of the zigzag pattern is measured to obtain the minimum dimension regarded as the groove bottom value.

The number of divisions on the tire circumference in the tire circumferential direction is equal to or smaller than the number of one unit of the tire which is the minimum unit forming the zigzag pattern. As a result, the tread groove is always included in the divided range.

Here, the tire 1 which is the minimum unit forming a zigzag pattern in the tire circumferential direction on the circumference of the used tire.
If you divide more than the number of circumferences, the tread groove may not be included in the divided range, and the measured value of the land (rib) part will be detected as the groove bottom value and the average value will be calculated. It becomes impossible to obtain the true outer diameter of the groove bottom.

Further, it is preferable that the number of divisions is equal to or less than the number of one unit of the tire which is the minimum unit forming the zigzag pattern. Thereby, for example, the influence of abnormal values such as deformation of the groove bottom and cracks (for example, stone bite cut) can be reduced.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the method for manufacturing a retreaded tire according to the present invention will be described below.

FIG. 1 relates to the present invention. The displacements of the tread groove bottom and the sidewall outer surface of a used tire are measured, and the outer diameter of the outermost belt and the outer diameter of the buff adjusting surface are measured from these measured values. FIG. 3 is a schematic diagram for explaining a method for calculating the dimension of the maximum tire width.

In FIG. 1, reference numeral 1 has a size of 10.0.
A used tire having a 0R20 belt 5 is rotatably held by regular rims 2 and 2a while keeping the positions of the left and right bead heels 3 and 3a at regular predetermined intervals W ₂ . A tread 10 having a tread groove 4 is arranged on the belt 5.

In this embodiment, the tread groove 4 has a zigzag pattern extending along the tire circumferential direction (arrow A direction) as shown in FIG.

In the zigzag pattern, the tread groove 4 extends obliquely toward one side in the tire axial direction starting from the center position V of the zigzag pattern in the tire axial direction (direction of arrow B), and then bent to bend in the tire axial direction. The minimum V-shaped minimum pattern element 4A (the tire circumferential direction length P) that extends obliquely to the other side and returns to the tire axial center position is alternately connected in the opposite direction.

In FIG. 1, reference numeral 40 is a reflection type optical non-contact type for measuring the radial displacement of the surface of the tread 10 with reference to the rotation center line XX of the used tire 1. Sensor of. The sensor 40 is movable by a feed screw 38 rotated by a motor 37 in parallel with the rotation center line XX of the used tire 1.

The sensor 40 is provided with a laser light source and a light receiving cell array, irradiates the surface of the tread 10 with laser light from the laser light source and projects the reflected light onto the light receiving cell array to detect the position on the array. The distance A from the sensor 40 to the surface of the tread 10 (including the tread groove 4) is measured.

Reference numeral 35 is a rotary encoder which is connected to the rotary shaft of the rim 2a.
That is, the rotation amount of the used tire 1 is detected. The rotation shaft of the rim 2a can be rotated by the motor 36.

The sensor 40 and the rotary encoder 35 are connected to a signal processing circuit 41. The signal processing circuit 41 includes an amplifier 42 that amplifies an output signal from the sensor 40, an A / D converter 43 that converts an analog output signal from the amplifier 42 into a digital signal, an arithmetic unit 44 that processes the digital signal, and a display unit. 45, and the output signal of the rotary encoder 35 is the arithmetic unit 4
4 The arithmetic unit 44 includes a CPU and a memory.

While the used tire 1 makes one revolution, the sensor 40 continuously measures the displacement of the surface of the tread 10,
The signal is sent to the amplifier 42 as an information signal of the distance A.
This signal is digitally processed by the A / D converter 43 and then sent to the arithmetic unit 44. Here, the attachment distance B of the sensor 40 from the rotation center line XX is known and constant.

Therefore, the computing unit 44 subtracts the distance A from the mounting distance B, calculates the size from the rotation center line XX to the surface of the tread 10 for one rotation of the tire, and stores it.

In the present embodiment, the sensor 40 is moved above the center position V in the tire axial direction of the zigzag pattern of the tread groove 4, and the displacement of the surface of the tread 10 is continuously measured.

The calculated results are shown in the graph of FIG. 3, for example. The vertical axis of the graph is the rotation center line X-
The dimension (mm) from X to the surface of the tread 10 and the horizontal axis represent the position (for one rotation) of the used tire in the tire circumferential direction.

Next, the computing unit 44 divides the tire circumference (actually on the stored data) into N equal parts in the tire circumferential direction, and divides the minimum range U _min (FIG. 3) in each of the divided ranges L. (Reference) is added to calculate the total value, and the calculated total value is divided by the number of divisions N to calculate the average value of the minimum dimensions. In this embodiment, this average value is the true radius C of the groove bottom.

The division number N is 10 or more, and when the tread groove 4 has a zigzag pattern as shown in FIG. 2, the minimum pattern included in the zigzag pattern having the length of one rotation of the tire. The number is less than or equal to the number of elements 4A.

Further, the computing unit 44 sets this true radius C to 2
The true outer diameter of the bottom of the groove is calculated by multiplying it by subtracting from the calculated true outer diameter (2C) twice the skid base gauge of this tire size, for example, 5 mm. The dimension of the outer diameter F is calculated.

Then, the size of the outer diameter F of the upper surface of the outermost belt layer 5A is displayed on the display. Further, in the calculator 44, the true radius C of the groove bottom is doubled and then the skid base gauge of 5 mm is subtracted to calculate the outer diameter D of the buff adjusting surface 6. Then, the dimension of the outer diameter D of the buff adjusting surface 6 which is this value is displayed on the display unit 45.

Such a treatment is applied to the used tire 1
This is performed over all or one or two of the tread groove bottoms 5 formed in the circumferential direction.

Next, reference numerals 50A and 50B are non-contact type sensors similar to the sensor 40 for measuring the displacement of the outer surfaces of the side wall portions 7 and 7a of the used tire 1.

The sensor 50A is mounted on the equatorial plane Y of the used tire 1 by the feed screw 61 rotated by the motor 60.
It is movable in the radial direction in parallel with −Y, and measures the distance from the sensor 50A to the outer surface of one sidewall portion 7.

The sensor 50B is movable in the radial direction in parallel with the equatorial plane YY of the used tire 1 by a feed screw 63 rotated by a motor 62, and the other sidewall portion 7a from the sensor 50B. It measures the distance to the outer surface.

The sensors 50A and 50B are the signal processing circuit 5
1, the signal processing circuit 51 is connected to the sensor 5
Amplifier 52 for amplifying the output signals from 0A and 0B, A / for converting the output signal from this amplifier 52 into a digital signal
The D converter 53, the arithmetic unit 54 which processes a digital signal, and the display 55 are provided.

When the used tire 1 is rotated, the sensor 5
0A, the dimension up to the point b, which is one point of the maximum width W ₃ of the sidewall portion 7, is measured.
The information signal of the distance Eb to the point is sent to the amplifier 52.

Similarly, the used tire 1 is rotated, and the sensor 50B measures the dimension up to the point f, which is the other point of the maximum width W ₃ of the sidewall portion 7a,
The information signal of the distance Ef from the sensor 50B to the point f is sent to the amplifier 52.

These signals are digitally processed by the A / D converter 53 and then sent to the calculator 54. Where the sensor 50
A mounting distance G from the equatorial plane YY of A and sensor 5
The mounting distance H of 0B from the equatorial plane YY is known and constant.

Therefore, by adding the distance G and the distance H and subtracting the distance Eb + Ef from this value, the width dimension from the point b to the point f on the outer surface of the sidewall portion 7, that is, the maximum width W ₃ The degree of maximum width W ₃ is displayed on the display unit 5
Display to 5.

The present invention is not limited to the above-described embodiment, and the sensors 40, 50A, B are not limited to the optical type, but may be, for example, an ultrasonic type, and can be displaced without contact. Any sensor may be used as long as it can measure.

Further, the sensors 40, 50A, B may be of a stylus type.

Distance W ₂ between the left and right bead heels 3, 3a
Is determined by the size of the used tire 1, and the shape of the outer surface of the bead portion 8 is almost the same depending on the size.

From the above, the dimension of the outer diameter D of the buff adjusting surface 6, the dimension of the maximum width W ₃ of the sidewall portions 7 and 7a,
The dimension of the interval W ₂ between the bead heels 3 and 3a and the shape dimension of the outer surface of the bead portion 8 can be specified.

Next, each dimension of the used tire 1 thus obtained is compared with the corresponding reference dimension of the mold to determine whether or not it is suitable for vulcanization molding by the mold. One embodiment of the determination method will be described.

A mold for vulcanizing and molding a raw tire (not shown)
Are available in three types of large, medium and small tire outer diameters.
For all molds, the allowable value of the mold is determined as a standard size corresponding to the size of the base tire portion that can be vulcanized and molded by the mold.

The allowable values of the mold of size 10.00R20 for which the base tire 9 obtained from the used tire 1 is to be vulcanized and molded are as follows.

Dimension of base tire part Allowable value of mold Mold outer diameter of outermost surface of belt upper surface F dimension central value ± αmm (1) Maximum width W ₃ dimension central value ± βmm (2) Then, the obtained outer dimensions of the outermost belt F of the outermost layer and the maximum width of W ₃ which are the respective dimensions are set to the respective allowable values (1) of the mold, As compared with (2), if all of the two dimensions are within the respective allowable values (1) and (2), it is determined that the mold is suitable for vulcanization molding and is possible. .

However, if any one of the above two dimensions is out of the range of the allowable value, it is determined that the vulcanization molding by this mold is unsuitable and impossible.

It should be noted that the allowable value of each size die is electrically stored in the memory circuit, and the allowable value and the size and maximum of the outermost belt upper surface outer diameter F calculated by the signal processing circuit are stored. It is also possible to electrically judge the suitability of the vulcanization molding by the mold by processing the size of W ₃ significantly by the comparison and judgment circuit.

Next, a tread of unvulcanized rubber was attached to the buff surface of the base tire, which was adjusted by buffing the tread portion of the used tire that was determined to be suitable for vulcanization molding using a mold. A retreaded tire can be manufactured by vulcanizing and molding the above.

According to one embodiment as described above,
Specifically, the following effects are obtained as compared with the conventional technique. (1) Before actually buffing a used tire, it is possible to judge the suitability of the vulcanization molding by the mold, and even if the vulcanization molding by the mold is not suitable, the used tire can be converted to the precure method. It was As a result, the damage ratio after buffing can be reduced by about 30%, and used tires can be effectively used. (2) It is no longer necessary for the operator to measure (and calculate) the required dimension of each part of the used tire with a tape measure, a depth gauge, a caliper, or the like. Measurement of groove bottom outer diameter with tape measure before buff and depth gauge,
Comparing the conventional technique for measuring the width with a caliper and the measurement and calculation by the method according to the present embodiment, it takes about 10 minutes per tire in the conventional technique, whereas in the present embodiment, I was able to reduce it to about 3 minutes. (3) The tire circumference is divided into N equal parts in the tire circumferential direction, the minimum dimension U _min in each of the divided ranges L is summed to calculate a total value, and the calculated total value is divided by the number of divisions N. Since the average value of the minimum dimensions is calculated and this average value is used as the true radius C of the groove bottom, the true radius C is doubled to calculate the true outer diameter of the groove bottom. Even if there are such problems, the outer diameter of the groove bottom can be measured easily and accurately.

Even in the case where the tread has the lug groove, the true outer diameter of the groove bottom can be obtained as described above. In this case, the sensor 40 is fixed at an arbitrary position above the lug groove, the tire circumference is divided into a number equal to or less than the number of lug grooves for one round of the tire at the measurement point, and the true dimension is determined based on the lowest dimension within the divided range. Get the outer diameter of the groove bottom.

When the tread groove 4 has a linear shape extending along the tire circumferential direction, the sensor 40 may be arranged above the center position of the groove width to measure the groove bottom outer diameter.

[0085]

As described above, according to the present invention, before the used tire is buffed and adjusted to form the base tire, the required dimension is measured to determine whether or not it is suitable for the mold vulcanization molding method. By doing so, the damage ratio after buffing can be reduced, and used tires can be effectively used.

In particular, it is not necessary for the operator to measure the required dimensions of each part of the used tire, and labor can be saved.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for measuring tire dimensions.

FIG. 2 is a plan view of a tread groove.

FIG. 3 is an example of a graph in which the displacement of the tread surface is measured.

FIG. 4 is a diagram showing a cross section in the width direction of a used tire according to a conventional technique.

FIG. 5 is a view showing a cross section in the width direction of a used tire according to a conventional technique.

[Explanation of symbols]

 1 Used Tire 3 Bead Heel 3a Bead Heel 3 4 Tread Groove 4A Minimum Pattern Element 5 Belt Layer 6 Buff Adjustment Surface 7 Sidewall 10 Tread 40 Sensor 41 Signal Processing Circuit 50A Sensor 50B Sensor 51 Signal Processing Circuit

Claims (3)

[Claims] 1. A rehabilitated tire is obtained by applying an unvulcanized rubber tread to a buff surface of a base tire prepared by buffing a tread portion of a used tire having a belt layer and then vulcanizing and molding the same with a mold. In manufacturing, before buffing the tread part of the used tire, measure at least the outer diameter of the tread groove bottom part and the tire maximum width of the sidewall part outer surface in advance using a non-contact sensor, and it can be applied to the mold A method for discriminating rehabilitated tires, which comprises determining at least 10 tires on the circumference of a used tire in the tire circumferential direction.
Divided into the above, the minimum dimension from the tire rotation center of the tire surface in the divided range is regarded as the groove bottom value, and obtained by doubling the average groove bottom value obtained based on the groove bottom values in all the ranges. The value is defined as the true outer diameter of the tread groove bottom portion, and the outer diameter dimension of the outermost belt upper surface of the belt layer and the outer diameter dimension of the buff adjusting surface are calculated from the true outer diameter of the tread groove bottom portion, Corresponds to the outer diameter dimension of the outermost belt upper surface and the tire maximum width dimension of the sidewall portion outer surface, and the dimension of the mold to be vulcanized and molded using the base tire obtained from this used tire. A method for discriminating rehabilitated tires, characterized by determining whether or not this used tire is suitable for vulcanization molding by a mold by comparing with respective reference dimensions. 2. A retreaded tire which is vulcanized by a mold after attaching an unvulcanized rubber tread to a buff surface of a base tire prepared by buffing a tread portion of a used tire having a belt layer. In manufacturing, before buffing the tread part of the used tire, measure at least the outer diameter of the tread groove bottom part and the tire maximum width of the sidewall part outer surface in advance using a non-contact sensor, and it can be applied to the mold A method for manufacturing a retreaded tire, which comprises rehabilitating a tire after determining the property thereof, the method comprising:
Divided into the above, the minimum dimension from the tire rotation center of the tire surface in the divided range is regarded as the groove bottom value, and obtained by doubling the average groove bottom value obtained based on the groove bottom values in all the ranges. The value is defined as the true outer diameter of the tread groove bottom portion, and the outer diameter dimension of the outermost belt upper surface of the belt layer and the outer diameter dimension of the buff adjusting surface are calculated from the true outer diameter of the tread groove bottom portion, Corresponds to the outer diameter dimension of the outermost belt upper surface and the tire maximum width dimension of the sidewall portion outer surface, and the dimension of the mold to be vulcanized and molded using the base tire obtained from this used tire. By comparing with the respective reference dimensions, it is determined whether or not this used tire is suitable for vulcanization molding by a mold, and the used tire determined by the above judgment to be suitable for vulcanization molding by a mold Calculate the tire tread Buffing is performed based on the outer diameter dimension of the buff adjustment surface to form a base tire, and a tread of unvulcanized rubber is attached to the buff surface of the base tire, followed by vulcanization molding with a mold for rehabilitation. A method for manufacturing a retreaded tire, which comprises manufacturing a tire. 3. When the tread groove has a zigzag pattern extending along the tire circumferential direction, the number of divisions on the tire circumference in the tire circumferential direction is set to be equal to or less than the number of one round of the tire which is the minimum unit forming the zigzag pattern. The method for producing a retreaded tire according to claim 2, wherein the minimum dimension is obtained by dividing and measuring the dimension from the center of rotation of the tire to the groove bottom at the axial center of the zigzag pattern.