JP2007331152A - Tire regeneration method using precured tread - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire regeneration method using a precured tread capable of sufficiently and smoothly discharge the whole of the air in pattern grooves to the outside of an envelope even in a case that the precured tread laminated to the periphery of a base tire has grooves extending in its width direction on its surface. <P>SOLUTION: In vulcanizing the precured tread 3, which is arranged to the periphery of the base tire 1, on the base tire 1 through a cushion rubber 2 in a reduced pressure atmosphere in the envelope 9 surrounding the precured tread 3 to bond the same to the base tire 1, the gas venting sheet 8, which covers the surface of the precured tread 3 over the whole periphery thereof, is arranged between the precured tread 3 and the envelope 9 and, for example, the envelope 9 is internally vented through the gas venting sheet 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a precured tread that has been vulcanized and molded in advance in a mold that is pasted around a base tire, in a vulcanizing can charged with an envelope that surrounds them, under pressure through the envelope. The present invention relates to a tire retreading method using precure tread that is vulcanized and bonded to the base tire, and at least exhausts the air in the pattern groove formed on the surface of the precure tread to the outside of the envelope sufficiently. In this way, we propose a technology that enables the envelope, and thus precure tread, to adhere to the base tire as expected.

In the conventional tire retreading method, the precure tread and the envelope are vulcanized and bonded to the pedestal tire via cushion rubber in a reduced-pressure atmosphere in the envelope surrounding them. During the process, cast a degassing sheet that covers the surface of the precure tread with only a portion in the circumferential direction, and at least in the vulcanization process of the cushion rubber in the vulcanization can, By discharging the air, the air in the pattern groove on the surface of the precure tread and the gas generated from the cushion rubber are discharged to the outside of the envelope, and as a result, the envelope in which the inside is a reduced pressure atmosphere, that is, Adhere the envelope whose inner pressure is lower than the outer pressure around the precure tread and the base tire. Of the pre-cure tread, it has been with the possible to generate the required pressing force to the base tire.
US Patent Specification No. 5007978

  In this prior art in which the degassing sheet is cast covering only a part of the precure tread in the circumferential direction, when the pattern groove on the surface of the precure tread is only the circumferential groove extending continuously in the circumferential direction, It is possible to exhaust all of the air in the pattern groove to the outside of the envelope sufficiently and smoothly due to the continuity of the circumferential groove even by the degassing sheet cast only in a part in the circumferential direction. However, when the surface pattern groove of the precure tread extends in each of the circumferential direction and the width direction and divides the block on the surface thereof, etc. With the conventional technology that distributes the venting sheet only to a part in the circumferential direction, in particular, all the air in the groove extending in the width direction is smoothly and sufficiently discharged to the outside of the envelope. This is because there is a narrowed portion of the groove width in at least one of the circumferential groove and the width direction groove extending in the circumferential direction, and there is a width direction groove that does not open in the circumferential groove, etc. Was particularly serious.

  And, due to these reasons, when the air in the groove cannot be sufficiently discharged, the internal pressure difference between the inside and outside of the envelope cannot be increased as expected, and as a result, the cushion rubber Since the precure tread cannot be pressed against the base tire with a predetermined force in the vulcanization process, the precure tread is sufficiently adhered to the base tire, directly to the cushion rubber, and vulcanized and bonded. As a result, there is a problem that a non-adhesive portion exists between the cushion rubber and the base tire and / or between the cushion rubber and the precure tread.

  An object of the present invention is to solve such problems of the prior art, and the object of the present invention is that a pre-cured tread bonded around a base tire has a circular shape on its surface. In addition to the circumferential groove that is continuous in the circumferential direction, of course, when there is no groove extending in the width direction of the circumferential groove, all the air in the pattern groove is sufficiently and smoothly provided. An object of the present invention is to provide a tire retreading method using a precure tread which can be discharged to the outside of the envelope.

  According to the present invention, there is provided a tire rehabilitation method using a precure tread in which a precure tread distributed around a base tire is subjected to a reduced-pressure atmosphere in the envelope surrounding them, for example, the inner side of the envelope from the outer side thereof. In an atmosphere of a low pressure of about 100 kPa, degassing covers the entire surface of the precure tread between the precure tread and the envelope when vulcanized and bonded to the base tire via cushion rubber. A sheet is disposed, and for example, the inside of the envelope is evacuated through the degassing sheet from the installation of the envelope to the end of vulcanization of the cushion rubber.

  Here, the precure tread can have a block such as a block pattern tire on its surface.

  In this rehabilitation method, more preferably, the surface of the precure tread is covered with a degassing sheet having irregularities for gas flow path formation on both front and back surfaces, and more preferably, the degassing sheet has a plurality of front and back through holes. It shall have.

  Also preferably, the gas venting sheet covers at least the surface of the precure tread from the side region interposing the cushion rubber, and preferably, the gas venting sheet is at least one place in the circumferential direction. Thus, the region from the surface of the precure tread to the beat toe of the base tire is covered.

  Furthermore, the surface of the precure tread is preferably covered with a gas vent sheet made of rubber, plastic or cloth.

  By the way, the precure tread can have not only the surface groove but also a back groove and a plurality of tread through holes reaching from the back surface to the tread surface.

  In the tire retreading method according to the present invention, the air in the pattern groove is removed at least during vulcanization by covering the entire surface of the precure tread on the base tire with a degassing sheet. When discharging to the outside of the envelope surrounding them through the gas venting sheet, regardless of the extending direction of the pattern groove and the groove width, the width direction groove ends without opening to the peripheral groove. However, under the action of the venting sheet, all of the air, generated gas, etc. that come in contact with it can be exhausted sufficiently and smoothly to the outside of the envelope, so that the pressure difference between the inside and outside of the envelope is always maintained. As expected, it is possible to effectively prevent the occurrence of problems caused by air or the like remaining in the pattern groove or the like in the envelope.

  Therefore, according to this method, the precure tread has not only the circumferential groove continuous in the circumferential direction on the surface but also the width direction groove in addition to the circumferential groove. However, even when there are blocks such as block pattern tires, rib / block pattern tires, etc., it is possible to ensure sufficient exhaust to the outside of the envelope.

And these things can be performed more smoothly when the surface of the precure tread is covered with a degassing sheet having concavo-convex portions for gas flow path formation on both front and back surfaces.
That is, the air between the gas vent sheet and the precure tread and the base tire can be sufficiently exhausted to the outside of the vulcanization can through the suction port provided in the outer envelope.

  And these things cover the surface of the precure tread with a degassing sheet having a plurality of front and back through holes, and let the air in the pattern grooves freely pass through those through holes, and the air etc. It is more effective when the flow is allowed on either side of the surface where the flow resistance is smaller.

  In addition, here, when the gas venting sheet covers at least the surface of the precure tread to the side region interposing the cushion rubber, it is between the cushion rubber and the precure tread and between the base tires. Each air or the like can be smoothly released through the degassing sheet. In addition, when the area from the surface of the precure tread to the bead toe is covered with a degassing sheet at least at one place in the circumferential direction, one piece of outer envelope is used to remove the air etc. that has escaped through the degassing sheet. It is possible to exhaust the air smoothly and sufficiently to the outside of the vulcanizing can through the suction port provided at the place.

By the way, when the surface of the precure tread is covered with a gas vent sheet made of rubber or plastic, the expected irregularities on the front and back surfaces of the gas vent sheet, and the required shape and Under the formation of the gas flow path having the dimensions, air or the like in the pattern groove can be discharged to the outside of the envelope more rapidly, smoothly and reliably.
The same applies to the case where the surface of the precure tread is covered with a cloth gas vent sheet.

  This rehabilitation method can be suitably used not only when the precure tread has only a surface groove, but also when it has a back groove and a plurality of tread through holes extending from the back groove to the tread surface. In this case, the surface of the precure tread through each through hole appropriately formed based on the internal / external differential pressure of the envelope, regardless of the extended form of the back groove To the outside of the envelope under the action of a venting sheet covering the entire surface of the precure tread, and smoothly evacuating in the same manner as described above. Residuals such as air can also be effectively prevented.

  FIG. 1 is a schematic cross-sectional view in the width direction showing the basic steps of the rehabilitation method according to the present invention. In the figure, 1 shows a base tire, and this base tire 1 is a used tire, usually a tread rubber. In addition to excision, the outer peripheral surface is buffed.

  An unvulcanized cushion rubber 2 having a required thickness is disposed on the outer peripheral surface of the base tire 1 over the entire circumference, and a flat plate is previously placed on the cushion rubber 2 in a mold. A pre-cured tread 3 having a desired tread pattern on the surface is pasted and arranged over the entire circumference to form a tire before vulcanization.

  Here, the tread pattern of the precure tread 3 is composed of a rib pattern having only circumferential grooves continuous in the circumferential direction. For example, a part of the tread pattern in FIG. As shown in the figure, the block 5 is composed of a plurality of circumferential grooves 4a that are bent in a zigzag shape and are continuous in the circumferential direction, and a block 5 that extends in the width direction and is divided into lateral grooves 4b that open to the adjacent circumferential grooves 4a. It has a block pattern, and each block 5 can also have auxiliary grooves 4c that end in the land portion without opening in any groove.

  Moreover, this precure tread 3 is exposed to the surface side by abrasion more than a predetermined amount on the surface of the tread regardless of the tread pattern on the surface thereof, as illustrated in the cross-sectional view in the width direction in FIG. In this case, when the cushion rubber 2 is vulcanized, a pre-curing such as air in the back groove 6 regardless of the extending form. In order to ensure a smooth and reliable flow toward the surface side of the tread 3, a plurality of tread through holes 7 reaching from the back groove 6 to the tread surface are formed at appropriate positions of the back groove 6.

  In the place shown in FIG. 1 again, the surface of the precure tread 3 of the tire formed by pasting the precure tread 3 on the unvulcanized cushion rubber 2 over the entire circumference, preferably made of rubber or plastic Or, it is covered with the gas vent sheet 8 made of cloth, and preferably, the covered area is the side area where the cushion rubber 2 is interposed from the surface of the precure tread 3, in other words, the precure tread 3 It is assumed that the side portion of the molded tire covers the cushion rubber portion interposed between the side edge and the base tire 1 completely.

  The cover area by the degassing sheet 8 is more preferably, as shown by the same cross-sectional view in FIG. 3, from the surface of the precure tread 3 at least at one place in the circumferential direction, more directly from the molded tire. Specifically, the entire region of the base tire 1 up to the bead toe is used.

  Here, the degassing sheet 8 applied in this way has an uneven portion for forming a gas flow path on both the front and back surfaces thereof, so that the air etc. that come into contact therewith can be smoothly moved out of the envelope. This is preferable for discharging, and this means that the gas vent sheet 8 having uneven portions further has a plurality of front and back through-holes and frees the flow of air or the like to the surface side having a smaller flow resistance. Effective in some cases.

After that, as illustrated in FIG. 4, the molded tire T is hermetically wrapped with the envelope 9 from both the inner and outer sides of the degassing sheet 8 in a required area of the degassing sheet 8, and is provided in the envelope 9. An exhaust tube 11 connected to the suction port is used to charge the molded tire T together with its envelope 9 into a vulcanizing can while venting an internal gas such as air under the action of negative pressure, for example. The vulcanization process is performed at a temperature of 95 ° C to 135 ° C.
In this case, each of the precure treads 3 takes into account the evacuation from the inside of the envelope 9 inside the envelope 9 based on the applied pressure of 0.5 MPa to 0.7 MPa, for example, in the vulcanizing can. Based on the difference in the set pressure (also 0.4 MPa to 0.55 MPa, for example), it is pressed against the base tire 1 with a sufficiently large force and is brought into close contact with the unvulcanized cushion rubber 2, and the exhaust Based on the continuation of the evacuation from the tube 11, the air in the surface groove of the precure tread 3 is generated along with the vulcanization of the cushion rubber 2 together with the air in the back groove when there is a back groove. The gas is discharged sufficiently and smoothly to the outside of the envelope 9, more preferably to the outside of the vulcanizing can.

  Therefore, in the product retreaded tire after vulcanization in this way, the cushion rubber 2 is vulcanized while air in the groove or the like remains in the vulcanized can without being sufficiently evacuated. Due to this, there is an effect that an essential problem in tire performance may occur between the cushion rubber and the pre-cured tread and between the base tire and the part that is not sufficiently vulcanized and adhered. Can be removed.

It is a width direction approximate line sectional view showing the basic process of the rehabilitation method concerning this invention. It is a partial development top view and width direction sectional view of a pattern which illustrates a precure tread. FIG. 3 is a schematic cross-sectional view in the width direction showing a state where a gas vent sheet covers up to a beat toe of a base tire. FIG. 3 is a schematic cross-sectional view in the width direction showing a state where a molded tire is enveloped in an airtight manner together with a gas vent sheet.

Explanation of symbols

1 tire 2 cushion rubber 3 precure tread 4a circumferential groove 4b lateral groove 4c auxiliary groove 5 block 6 back groove 7 tread through hole 8 degassing sheet 9 envelope 10 suction port 11 exhaust tube T molded tire

Claims (8)

In vulcanizing and bonding precure treads arranged around the base tires to the base tires via cushion rubber in a reduced pressure atmosphere in the envelope surrounding them,
A tire using a precure tread, in which a degassing sheet is disposed between the precure tread and the envelope to cover the entire surface of the precure tread over the entire circumference, and the air is evacuated through the degassing sheet. Rehabilitation method.   The tire retreading method using the precure tread according to claim 1, wherein the precure tread has a block on a surface thereof.   The tire retreading method using the precure tread according to claim 1 or 2, wherein the surface of the precure tread is covered with a degassing sheet having concavo-convex portions for gas flow path formation on both front and back surfaces.   The tire retreading method using the precure tread according to claim 3, wherein the surface of the precure tread is covered with a gas vent sheet having a plurality of front and back through holes.   The method for retreading a tire using the precure tread according to any one of claims 1 to 4, wherein the degassing sheet covers at least the surface of the precure tread to the side region interposing the cushion rubber.   The tire using the precure tread according to any one of claims 1 to 5, wherein the region from the surface of the precure tread to the bead toe of the base tire is covered with a degassing sheet at least at one place in the circumferential direction. Rehabilitation method.   The tire retreading method using the precure tread according to any one of claims 1 to 6, wherein the surface of the precure tread is covered with a gas vent sheet made of rubber, plastic or cloth. The tire retreading method using the precure tread according to any one of claims 1 to 7, wherein the precure tread has a back groove and a tread through hole extending from the back groove to the tread surface.

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