JP2017042996A - Vulcanization method of pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vulcanization method of a pneumatic tire capable of shortening a total vulcanization time by supplying a pressurizing medium up to a pressure capable of holding properly a low cover, into a bladder in a short time, even when the tire or the bladder has a large size.SOLUTION: There is provided a vulcanization method of a pneumatic tire for vulcanizing a low cover by using a tire vulcanization apparatus having a vulcanization mold and a bladder. In the vulcanization method of the pneumatic tire, when performing shaping for holding the low cover by supplying a pressurizing medium into the bladder to expand the bladder, the shaping is performed by switching a supply pressure of the pressurizing medium in two stages from a high pressure to a low pressure.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vulcanizing method for a pneumatic tire in which a raw cover is vulcanized using a vulcanizing apparatus equipped with a bladder.

  Generally, a pneumatic tire is manufactured by heating and pressurizing a raw cover set in a vulcanizing apparatus using a vulcanization mold and a bladder.

  At this time, so-called shaping is performed in which a pressurized medium is supplied into a bladder inserted into the inner cavity of the raw cover before the start of vulcanization so that the tire shape of the raw cover is maintained (Patent Document 1, 2).

  In this shaping, if the pressure to supply the pressurized medium is too high, the bladder may expand rapidly and may protrude from the raw cover, causing defects, or the bladder may expand and contract greatly, resulting in premature deterioration of the bladder. is there. In addition, the raw cover may be stretched by a greatly expanded bladder, and rubber may be caught in the vulcanization mold.

  For this reason, conventionally, the standard supply pressure (standard pressure) of the pressurized medium in shaping is set to 0.04 to 0.08 MPa.

JP 2002-36245 A JP-A-9-300356

  However, tires and bladders vary in size, and if the standard pressure is uniformly set to 0.04 to 0.08 MPa, when the tire or bladder size increases, the low cover is properly held in the bladder. The time for supplying the pressurized medium to a pressure that can be increased, and the total vulcanization time is also increased.

  Accordingly, the present invention provides an air that can reduce the total vulcanization time by supplying the pressurized medium to a pressure that can appropriately hold the raw cover in the bladder in a short time even when the size of the tire or bladder is large. It is an object of the present invention to provide a method for vulcanizing a filled tire.

  The inventor has intensively studied and found that the above-described problems can be solved by the invention described below, and has completed the present invention.

The invention described in claim 1
A pneumatic tire vulcanizing method for vulcanizing a raw cover using a tire vulcanizing device having a vulcanizing mold and a bladder,
When shaping the bladder to expand and hold the raw cover by supplying a pressurized medium into the bladder, the supply pressure of the pressurized medium is switched from high pressure to low pressure in two stages. This is a method for vulcanizing a pneumatic tire.

The invention described in claim 2
The method for vulcanizing a pneumatic tire according to claim 1, wherein the high pressure is 0.08 to 0.2 MPa, and the low pressure is 0.04 to 0.08 MPa.

The invention according to claim 3
The method for vulcanizing a pneumatic tire according to claim 1 or 2, wherein the pressure is switched from the high pressure to the low pressure when the pressure in the bladder rises to a state where the raw cover can be held. It is.

The invention according to claim 4
The method for vulcanizing a pneumatic tire according to claim 3, wherein switching from the high pressure to the low pressure is performed when the pressure in the bladder reaches 0.01 to 0.03 MPa.

  According to the present invention, even when the size of a tire or a bladder is large, the pressure medium can be supplied to a pressure that can appropriately hold the raw cover in the bladder in a short time, and the total vulcanization time can be shortened. It is possible to provide a method for vulcanizing a filled tire.

It is a figure which shows typically the vulcanization | cure apparatus used for the vulcanization method of the pneumatic tire which concerns on one embodiment of this invention. It is a block diagram explaining supply of the pressurization medium in the vulcanization method of the pneumatic tire concerning one embodiment of the present invention. It is a block diagram explaining supply of the pressurized medium in the conventional vulcanization method of a pneumatic tire. It is a graph explaining the change of the pressure in a bladder in the vulcanization method of the pneumatic tire concerning one embodiment of the present invention.

  Hereinafter, the present embodiment will be described with reference to the drawings.

1. Tire Vulcanizing Device FIG. 1 is a diagram schematically showing a vulcanizing device used in the method for vulcanizing a pneumatic tire according to the present embodiment. FIG. 2 is a block diagram illustrating the supply of a pressurized medium in the pneumatic tire vulcanizing method according to the present embodiment. FIG. 3 is a block diagram for explaining supply of a pressurized medium in a conventional pneumatic tire vulcanization method.

  As shown in FIG. 1, the vulcanizing apparatus 1 used in the present embodiment includes a vulcanizing mold 16, a bladder 24, and a central mechanism 10 that supplies a pressurized medium to the bladder 24. The same as in the conventional vulcanizing apparatus.

  The vulcanization mold 16 includes an upper mold 12 and a lower mold 14 that are separable in the vertical direction, and a bladder 24 is disposed in the inner cavity of the raw cover T set in the vulcanization mold 16.

  The central mechanism 10 is provided with a supply port 20 for supplying a pressurized medium into the bladder 24 and a discharge port 22 for discharging the pressurized medium in the bladder 24 to the outside.

  However, the vulcanizing apparatus in the present embodiment is different from the conventional method in supplying the pressurized medium to the supply port 20.

  That is, in the present embodiment, the supply pipe 20 shown in FIG. 2 is connected to the supply port 20 in FIG. 1, and a shaping booster 32 is provided in the middle of the supply pipe 30. The shaping booster 32 is provided with two pressure reducing valves and an electromagnetic valve for switching between the two pressure reducing valves. Note that one electropneumatic proportional valve can be used instead of two pressure reducing valves.

  Each of these pressure reducing valves is set so as to reduce the pressure medium to a different pressure and supply it to the bladder. Specifically, one of the pressure reducing valves is supplied with a pressure medium supplied from a pressure medium supply device (not shown) at a predetermined pressure (main pressure: 0.1 MPa in FIG. 2) as a standard pressure (FIG. 2 is reduced to a pressure higher than 0.05 MPa) (0.1 MPa in FIG. 2) and supplied into the bladder. The other pressure reducing valve reduces the main pressure to a low pressure equivalent to the conventional standard pressure and supplies the pressurized medium into the bladder.

  On the other hand, in the conventional tire vulcanizing apparatus, as shown in FIG. 3, one pressure reducing valve or electropneumatic proportional valve is attached to a shaping booster 52 provided in the middle of the supply pipe 50. By using this pressure reducing valve or electropneumatic proportional valve, the pressurized medium supplied from the pressurized medium supply device at the main pressure is reduced to the standard pressure and supplied into the bladder.

2. Pneumatic tire vulcanizing method Next, a pneumatic tire vulcanizing method using the vulcanizing apparatus in the present embodiment described above will be described. FIG. 4 is a graph for explaining a change in pressure in the bladder in the method for vulcanizing a pneumatic tire according to the present embodiment. A solid line 38 in FIG. 4 indicates a change in pressure in the bladder in the method for vulcanizing a pneumatic tire according to the present embodiment. In FIG. 4, a change in pressure in the bladder in a conventional pneumatic tire vulcanization method is indicated by a dotted line 40 for comparison.

  In the vulcanizing method for a pneumatic tire according to the present embodiment, as in the conventional method, after setting the low cover held by the loader in the vulcanizing mold, the pressurized medium is supplied into the bladder of the vulcanizing apparatus. As a result, shaping is performed to maintain the tire shape by inflating the bladder in the inner cavity of the raw cover.

  In this embodiment, at the time of shaping, the supply pressure of the pressurized medium is switched from high pressure to low pressure in two stages. Specifically, as a first stage, one of the pressure reducing valves is used to reduce the pressure medium supplied at the main pressure to a pressure higher than the conventional standard pressure and supply it to the bladder. As a result, the bladder expands in the inner cavity portion of the raw cover held by the chuck of the loader and tries to hold the raw cover.

  Thereafter, when the pressure in the bladder (0.015 MPa in FIG. 4) increases until the expanded bladder can hold the raw cover, a signal for starting the chuck closing operation to the loader is issued from the controller of the vulcanizer. The chuck starts to close. At this time, the supply pressure of the pressurized medium is switched to a lower pressure than the first stage in accordance with the start of the chuck closing operation, and the pressurized medium is further supplied (second stage).

  As a result, the subsequent expansion of the bladder is moderated, and the bladder can be appropriately prevented from sticking out, and the bladder can be held along the tire.

  After the chuck closing operation is completed, move the loader to the outside of the vulcanization mold, then close the upper and lower molds of the vulcanization mold and heat and press the bladder and vulcanization mold to vulcanize the low cover. I do.

  Thus, in the present embodiment, when shaping, until the bladder can hold the raw cover, as a first step, the pressure for supplying the pressurized medium is high, so the size of the tire or bladder is Even if it is large, as can be seen from the solid line 38 and the dotted line 40 in FIG. 4, the pressure in the bladder can be increased in a shorter time than in the prior art to hold the raw cover. And since the pressure which supplies a pressurization medium as the 2nd step after that is made into the low pressure similar to the past, the protrusion of a bladder can be prevented appropriately and a bladder can be hold | maintained along a tire. As a result, the time required for shaping can be shortened compared to the conventional case, and the total vulcanization time can be shortened.

  In the above, the high pressure in the first stage, the low pressure in the second stage, and the pressure at the time of switching from the first stage to the second stage are all set according to the tire to be used. Is preferably 0.08 to 0.2 MPa, the low pressure in the second stage is 0.04 to 0.08 MPa, and the pressure when switching from the first stage to the second stage is preferably 0.01 to 0.03 MPa.

  In the above-described embodiment, the high pressure and the low pressure are switched by switching two pressure reducing valves set to different pressures, but the present invention is not limited to this, and the pressure is reduced to two or more types of pressures. One electropneumatic proportional valve that can be used may be used to switch between high pressure and low pressure.

  Hereinafter, the present invention will be described with reference to examples.

  In the following, vulcanization was performed after shaping using two types of raw covers having tire sizes different from 275 / 70R16 and 225 / 65R17.

A. Shaping time First, the time required for shaping the raw cover was evaluated.

1. Examples and Comparative Examples In the examples, the raw cover was vulcanized after shaping according to the above-described embodiment of the present invention. Specifically, by supplying the pressurizing medium at a high pressure of 0.1 MPa, when the pressure in the bladder is increased to 0.015 MPa, the pressure medium is switched to a low pressure of 0.05 MPa. Shaping was performed.

  In the comparative example, the raw cover was vulcanized after shaping by a conventional method. Specifically, shaping was performed by supplying a pressurized medium at a standard pressure (0.05 MPa).

2. Evaluation method The time required for shaping the raw cover of each tire size was measured.

3. Evaluation results (1) When the size of the raw cover is 275 / 70R16 In the comparative example, it took 32 seconds from the start of shaping until the vulcanization mold was closed. In contrast, in the example, it was confirmed that the time from the start of shaping to the closing of the vulcanization mold was 30 seconds, and the time required for shaping was shortened by 2 seconds.

(2) When the size of the raw cover is 225 / 65R17 In the comparative example, it took 35 seconds from the start of shaping until the vulcanization mold was closed. In contrast, in the example, it was confirmed that the time from the start of shaping to the closing of the vulcanization mold was 33 seconds, and the time required for shaping was shortened by 2 seconds.

  From the results of (1) and (2) above, it was confirmed that the time required for shaping can be shortened by supplying the pressurized medium in two stages during shaping.

B. Next, the dry cycle in the vulcanization process was evaluated.

  100 raw covers each having a size of 225 / 65R17 were vulcanized according to the above-described Examples and Comparative Examples, and the average time required for the dry cycle (cycle from the start to completion of vulcanization) was measured.

  As a result, in the case of the comparative example, the average dry cycle time was 79 seconds. On the other hand, in the case of the example, the average time of the dry cycle was 77 seconds, and it was confirmed that the dry cycle time was shortened by 2 seconds as compared with the comparative example.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Vulcanization apparatus 10 Center mechanism 12 Upper mold | type 14 Lower mold | type 16 Vulcanization mold 20 Supply port 22 Discharge port 24 Bladder 30, 50 Supply piping 32, 52 Shaping booster 38 Pressure change of this embodiment 40 Conventional pressure change T Raw cover

Claims (4)

A pneumatic tire vulcanizing method for vulcanizing a raw cover using a tire vulcanizing device having a vulcanizing mold and a bladder,
When shaping the bladder to expand and hold the raw cover by supplying a pressurized medium into the bladder, the supply pressure of the pressurized medium is switched from high pressure to low pressure in two stages. A method for vulcanizing pneumatic tires.   The method for vulcanizing a pneumatic tire according to claim 1, wherein the high pressure is 0.08 to 0.2 MPa, and the low pressure is 0.04 to 0.08 MPa.   The method for vulcanizing a pneumatic tire according to claim 1 or 2, wherein the pressure is switched from the high pressure to the low pressure when the pressure in the bladder rises to a state where the raw cover can be held. .   The method for vulcanizing a pneumatic tire according to claim 3, wherein the switching from the high pressure to the low pressure is performed when the pressure in the bladder reaches 0.01 to 0.03 MPa.

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