JPH0655371B2 - Tire molding method and mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and a mold for molding a tire, and more particularly to a tire molding method and a mold for preventing accumulation of air in a tire mold. Regarding In particular, the invention also relates to methods and molds for molding tires without the need for mold air holes.

[Conventional technology]

Tires are usually manufactured by molding uncured or uncured tires in a tire building machine. Next, this unvulcanized tire is taken out from the tire molding machine and placed in a tire mold (hereinafter, also referred to as a mold or a mold). The tire mold can be kept in a predetermined shape by applying heat and pressure to the unvulcanized tire so as to match the unvulcanized tire with the cavity or cavity shape of the tire mold and then vulcanized and cured. Is formed. The cured tire preferably matches the cavity shape of the tire mold, and whether or not it depends on whether or not air is trapped between the uncured tire and the mold cavity surface. There is.

Conventionally, the air existing between the uncured tire and the surface of the mold cavity has been removed by a plurality of small diameter passages or small holes extending from the surface of the mold cavity to the outside of the mold through the inside of the mold.
That is, as the uncured or unprocessed tire in the mold is pressed against the surface of the mold cavity, the air trapped between the unprocessed tire and the surface of the mold cavity passes from the mold cavity through a small diameter passage or a small diameter hole. Is extruded. These small passages or small holes are commonly referred to as "vents".

By the way, these air vents are originally provided to discharge air from the mold, but the unprocessed rubber that is a part of the unprocessed tire to be molded discharges stagnant air from the mold. Immediately after this, it penetrates into these ventilation holes. The unprocessed rubber that has entered the ventilation holes is processed in the ventilation holes and remains attached to the processed tire even after the completion of processing. Therefore, when the mold is opened and the processed tire is taken out, the unprocessed rubber in the vent hole becomes a large number of needle-shaped projections that project almost vertically from the surface of the processed tire. The term "vent holes" is commonly used for these needle-like protrusions, and these needle-like protrusions deteriorate the appearance of the tire.

These needle-like protrusions protruding from the processed tire are usually removed by machine-loading the processed tire. That is,
A machined tire is installed on this machine and these needle-like projections are cut or removed from the tire automatically or manually.
This process of cutting and removing protrusions, called "vent hole removal", causes the manufacturing cost of the tire to rise sharply. Furthermore, if the vent hole removal work is not successful and the tire surface is damaged due to the incision on the tire, it may cause considerable damage. A large amount of wasted tires will result. In addition, the tire surface after the work of removing the air holes has an unfavorable appearance as a whole.

During the molding process, it has been proposed to remove air from the cavities that require vacuum, eliminating the need for at least some mold vents. Therefore, in the proposal illustrated in US Pat. No. 1,276,411, multiple tire molds were placed in a large press space and the press spaces were evacuated, thereby removing air from the multiple molds. And the press is done,
The mold was compressed in the cavity to form the final tire.

In another proposal, illustrated in U.S. Pat.No. 2,779,386, a vacuum is introduced along the parting line into the mold so that the tread portion and ply portion of the uncured tire are between the tire frame and the inner layer. To form an air passageway from the area adjacent to the middle section to remove trapped air from this area,
I was pierced.

U.S. Pat.Nos. 4,347,212, 3,842,150 and 3,854,
In yet another proposal, illustrated in U.S. Pat. No. 852, a plurality of bulbs were disposed embedded within the mold, particularly along the sidewalls of the mold. The valve in this proposal is configured to open when the mold is closed and to expel air from within the mold when the uncured tire is pressed against the mold surface of the mold. Desirably, the valve is
It is closed before it is affected by the rubber that is forced into the valve during the molding process. Each valve is connected to a vacuum source to act to empty the mold. Others have poppet valves in the tread rather than the sidewalls of the mold.

In yet another proposal, illustrated in U.S. Pat.No. 3,983,193, the uncured tire portion applied in a retread (re-tread) operation is surrounded by an elastomer bag having a vacuum suction port, whereby A vacuum space is molded around the retreaded tire.

The proposals mentioned above have failed to achieve commercial success for various reasons. When multiple molds are provided in an air removal press for molding, it is generally shown that the time limits along with the assembly and disassembly of the mold, including the uncured tire to perform the fluid press, can be quite expensive. ing. In particular, because of the process of creating a vacuum along the parting line to expel air from the inside of the frame portion of the uncured tire, an important, reliable and effective vacuum cannot be obtained, such a process In which a commercial disadvantage was brought. When multiple poppet-type valves are placed, for example, along the sidewall of a tire mold, the difficulty in deflating the tread portion of the mold produces fewer unacceptable majority than acceptable quality tires. It was decided to do. The difficulty in assembling and disassembling an uncured tire packaged in such a bag in the process of surrounding a portion of the uncured tire where the polymer bag is applied to the retread substantially causes commercial disadvantages. I was there.

A method in which good quality tires are produced without the need to provide ventilation holes, i.e. so-called vents, in the tire mold, and without extending the process cycle during pressing of the tire mold, is by reducing the equipment of expensive tire vents. Also, by saving the rubber lost in the venting operation, substantial utility could be found in the commercial production of tires.

Japanese Examined Patent Publication No. 33-8540 discloses a molding method and a tire mold capable of producing a tire having no vent hole. In this molding method and tire mold, there is no hole in the cavity corresponding to the surface of the tire, and a hole for vacuuming is opened at a position on the dividing line of the tire mold. A vacuum is introduced in a partially closed position of the tire mold, and then the tire mold is completely closed. In order to produce a tire of good quality, the inventor of the present invention applies a desired vacuum level from the time when the tire mold is partially closed to the time when the tire mold is completely closed and the tire is completely molded. I realized I needed to maintain. Furthermore, it has been found that it is necessary to apply an optimum pressure and time when the inside of the tire mold is evacuated. And while satisfying these conditions,
In order to maintain the desired vacuum level, it is necessary to improve the sealing performance.

[Means for solving problems]

The method according to the present invention is a method of forming an uncured tire having a tread portion, a side wall portion and a bead portion, and then molding the uncured tire in a tire mold, the tire mold defining a cavity. It has a tread portion, a side wall portion and a bead portion, the mold portion basically has no air holes leading from the inside of the cavity to a point outside the mold, and the tire mold divides the mold into a plurality of divided bodies. Having a dividing line in the circumferential direction, the dividing body is a method of molding a tire by closing the dividing line, the uncured tire is placed in a mold, and 5.08 cm and 0.10 cm along the dividing line. The mold is partially closed so as to open by a distance in the range between, and the elastically deformable seal that seals the parting line in the radial direction outside the tread part allows air to enter the cavity along the parting line. To flow in Qualitatively blocking and substantially blocking the inflow of air into the cavity by sealingly closing other passages through which air can enter the cavity, the seal being circumferentially wide in the axial direction. Is a strip-shaped seal extending in the direction of one end of the die in the axial direction is supported by the outer periphery of one of the divided bodies of the mold, and the other end of the seal in the axial direction of the die protrudes from the one divided body. Extends toward the outer periphery of the other split, and these splits
at least 1 on the parting line at the radial middle of the tread part and the seal, engaging the outer circumference of the other part when partially closed at a distance in the range between cm and 0.10 cm.
By applying a vacuum from a vacuum source to the point, the cavity is evacuated to an absolute pressure of 16932 Pascal or less for a time of about 60 seconds or less, and the seal is designed to enhance the airtightness of the seal by evacuating the cavity. , The mold is completely closed and the tire is cured.

Further, the tire mold according to the present invention to which the method can be applied is a tire essentially having no sidewall vents, bead vents and tread vents that project beyond the outermost surfaces of the bead portion, sidewall portion and tread portion of the tire. A tire mold for molding a tread portion that constitutes a cavity,
A tire mold having a side wall portion and a bead portion, and the mold is divided into a plurality of divided bodies by a circumferential dividing line intersecting with an outer peripheral surface of the tire, and the divided body closes the dividing line to mold a tire. A mold inner surface consisting of a bead portion, a tread portion and a side wall portion which does not have a ventilation outlet for letting the fluid flow out from the inside of the cavity, and a point on the dividing line radially outside the tread portion is vacuumed. At least one conduit means in communication with the source, the conduit means being disconnectably connected to the vacuum source, the conduit means and the vacuum source having a vacuum of 60 seconds or less with the mold sealed. 16932P cavity by applying pressure
It has a structure capable of exhausting to an absolute pressure of a or less, and is equipped with a split line elastically deformable seal, which is a band-shaped seal extending in the circumferential direction with a width in the axial direction, and one end of the seal in the axial direction is a mold. The other end of the seal in the axial direction is supported by the outer peripheral portion of one of the divided bodies and extends toward the outer peripheral portion of the other divided body of the mold from the one divided body, and these divided bodies are 5.08 cm. Engages the outer circumference of the other split when partially closed at a distance in the range between
This sealing arrangement makes the seal more airtight during evacuation of the cavity, the seal being able to substantially prevent air from flowing into the cavity in the partially closed state, and It is characterized in that it is configured to continue to prevent the inflow of the air during and after the coupling operation of.

[Action effect]

In the above configuration, a vacuum is introduced with the mold partially closed at a predetermined opening, and then a vacuum is drawn at a predetermined vacuum level for a predetermined time, and then the tire mold is completely closed to cure the tire. Mold. Since the tire is molded by applying heat and pressure, there is an optimum time from the insertion of the tire into the mold to the completion of molding, and the initial evacuation time and vacuum level of the tire mold must be determined accordingly. There is. There is also an optimum relationship between the partial opening of the tire mold and the vacuum level or the evacuation time. The present invention satisfies such optimum conditions.

When a vacuum is introduced into the tire mold, the above-described parting line seal is configured to become more tightly sealingly engaged with the tire mold by the vacuum, and the inside of the tire mold is maintained at a predetermined vacuum level. Is something that can be done. Therefore, by using such a dividing line seal, it is possible to manufacture a tire of excellent quality without air holes.

〔Example〕

The present invention provides methods and molds for making tires mouldably. In accordance with the method and apparatus of the present invention, when the finished tire emerges from the mold, a large number of conventional tire outer surfaces made by vulcanizing a tire rubber compound in vent holes provided in conventional tire molds. There are no overhangs. Referring to the drawings, a mold 10 useful in the practice of the present invention is shown in FIGS. 1, 2 and 7.

Referring to FIG. 2, the mold 10 is used in a tire press 12 partially shown in the same figure.
The mold 10 comprises a lower or male portion 14 and an upper or female portion 15. Male part 1 at the parting line 16
4 and a female part 15 are separated, these parts 14,
At least one of 15 is movable in a direction perpendicular to the dividing line 16 and away from the other part. Part 14,1
Separation of 5 opens the mold 10 for the introduction of the unvulcanized tire to be molded. Each mold part 14, 15 comprises a tread ring part 19, 20, a side wall part 23, 24 and a bead ring part 27, 28. In some press-molded configurations, the bead ring portions 27, 28 will be more appropriately connected to the press 12, but for simplicity of the present description, the bead ring portions 27, 28 are Tread portions 19 and 20 and side wall portion 2 of the mold 10.
Think with 3,24. The unvulcanized tire 30 is received in the mold. The unvulcanized tire has a tread portion 31, a side wall portion 32 and a beat portion 33.
When the mold 10 is closed along the parting line 16, the mold surface 35 is defined by the mold tread portions 19, 20, sidewall portions 23, 24 and bead portions 27, 28. Mold surface 35 may be constructed in a known manner to facilitate air movement during mold evacuation.
A mold cavity, indicated generally by the reference numeral 37, is defined in the mold.

The bag body 39 is provided in the mold cavity 37. The lower fastening ring 40 and the upper fastening ring 41 play a role of holding the bag body in the mold cavity. The upper fastening ring 41 cooperates with the upper mold ring 43 to hold the upper ring 44 of the bag body, while the lower fastening ring 40 cooperates with the lower bead ring 45 to hold the lower bag ring 46. . The upper bead ring 47 is held in the mold 10. The lower fastening ring 40 is held on the press 12 using a screw ring 48.

During use, the pressurized fluid is introduced into the bag body 39, which causes the bag body 39 to expand with respect to the unvulcanized tire 30. Therefore, the unvulcanized tire is pressed against the forming surface of the mold cavity, that is, the tire forming surface 35. The tire forming surface 35 or forming surface is a ridge 50 that can assist in forming the desired shape of the final cured tire.
May be provided. While the mold 10 is being heated, the unvulcanized tire 30 is pressed against the mold surface 35 to create a final tire having a cured or sulfurized rubber component that curatively conforms to the contours of the mold surface 35 and the ridges 50. .

The mold 10 described herein is representative of some tire molds used in the formation of tubeless tires, particularly in the industry. One significant difference between the mold 10 of FIG. 2 and a conventionally used mold is that there are a plurality of stomal passages or paths extending from the molding surface 35 through the mold to a location external to the mold and press. There is no opening at all. Such stoma passages, commonly known as vents, are provided to expel air. Without such stoma passages, air would be trapped between the molding surface 35 and the unvulcanized tire 30 during the tire building operation. If the air is not properly removed by the vents, the trapped air will cause the unvulcanized tire 30 to not completely conform to the contour of the molding surface 35, resulting in a final cured tire, and in particular a cured tire. This causes defects on the outer surface of the cured rubber.
The trapped air does not act as an insulator, delays the curing process and helps the incompletely cured final tire.

In the present invention, the mold is modified to include conduit means 52 which can be intermittently connected to a vacuum source (not shown in FIG. 2). The conduit means 52 or vacuum conduit means connects between the point 53 on the parting line 16 and the vacuum source. The location 53 is located radially outward of the tread portions 19, 20. Typically, such conduit means 52
Can be formed by cruciform perforations in the mold 10. The criss-cross perforations can range in size from about 0.635 cm to about 5.08 cm in diameter. At least one conduit means 5
2 is provided along the dividing line, the tire mold 10
Diameter, volume of mold cavity 37 and conduit means 5
Depending on the dimension of 2, it may be desirable to provide a plurality of conduits 52 annularly spaced around the tire mold 10 along the parting line 16.

Between the upper bead ring 47 and the mold portion 15, and
A boundary surface 9 is formed between the lower bead ring 14 and the mold portion 14.
There is 0. The upper bead ring 47 is held to the mold portion 15 using fasteners 98. The interface 90 between the mold portion 15 and the upper bead ring 47 is typically filled with rubber during the first tire cure cycle. Therefore, the rubber fills the interface 90. Once cured,
From the outside of the mold 10 to the mold cavity 37
Effectively seals the interface 90 against the movement of air in. The small wedge 99 formed on the portion 15 or the bead ring 47 along the interface 90 substantially assists in sealing the interface 90.

The embodiment of FIG. 2 shows a mold 10 and a portion of a commercially available press 12 known as a McNeil BOM press. The mold 10 of FIG. 2 has a concave cutout 8 for receiving a covering seal 81 having a bevel 83.
Has 0. The coated sealing material uses a fastening ring 82 which is tightened to hold the sealing material 81, and the recessed cut portion 8 is formed.
Holds within 0. The seal member 81 is a band-shaped seal having a width in the axial direction and extending in the circumferential direction. One end portion of the seal in the axial direction is supported by the outer peripheral portion of the female portion (one of the divided bodies of the mold) 15, and the axial line of the seal is formed. The other end of the direction is female part 1
Projecting from 5 and extending towards the outer circumference of the male part (the other part of the mold) 14, these parts 14, 15 being 5.08 cm and 0.
It is adapted to engage the outer periphery of the male portion 14 when partially closed at a distance in the range of 10 cm. The chamfered or rounded portion 84 of the male portion 14 helps the sliding of the sealing material 81. The bead seal material 92 is held in a recess or notch 96 provided in the lower bead ring 45. The bead seal retainer 94 held by the fastener 95 helps to hold the bead seal material 92 in the notch 96. The bead seal material 92 is elastically deformed from a rest position, shown imaginarily at 97, to an operative position achieved when the bead ring 45 is seated against the mold portion 14 by compressing the seal material 92. It is possible. A dowel pin assembly 110 having a dowel bush 112 and a dowel pin 114 is provided. The fasteners 115, 116 serve to hold the dowel pin 114 and dowel bush 112 within the assembly.
A plurality of dowel pin assemblies 110 are spaced radially outward of the tread portions 19, 20 along the parting line 16 such that the dowel pin assemblies 110 act to align the mold during the closing operation.

The vacuum conduit means 52 is arranged radially inward of the covering sealing material 81. The coated seal material 81 and the bead seal material 92 have a mold of at least about 0.10 cm and 5.
It is designed to engage in airtightness at one or more points during partial opening at a point between 08 cm and to maintain airtight engagement during subsequent full closure of the mold. . Typically, the bead ring 45 is seated and the seal 9
2 is engaged before the mold 10 is closed.

Preferably, the sealing materials 81, 92 are highly deformable, and the mold parts 14, 15 have a distance of 0.
While being kept separated by 10 cm and 5.08 cm, the sealing material 81 is formed so that the sealing relationship between the mold parts 14, 15 can be achieved in one or more places. The sealing material 81, 92 is from 0.10 cm of the sealing material 81.
It must provide a continuous seal from the initial engagement point in the range of 5.08 cm until the mold is fully closed for tire vulcanization. The sealing materials 81, 92 should be sealed in such a way that movement of air along the parting line 16 and the interface 90 from the outside of the mold into the mold cavity 38 is essentially prevented.

When selecting the sealing materials 81 and 92, the sealing material 8
It is important that 1,92 be formed substantially elastically. The sealing material is deformed, otherwise, between the parts 14 and 15 of the mold 10 and the parts 14 and 1 of the mold 10.
If it becomes insufficiently elastic to seal between 5 and the bead annulus, air will flow along the parting line 16 and outside the mold 10 between the mold parts 14, 15 and the bead annulus. Would move to the mold cavity 37. Inadequate evacuation of air from mold cavity 37 results in a substantial increase in the likelihood of improper formation of unvulcanized tire 30.

Referring to the drawings, FIG. 1 shows a modified embodiment of a mold 10 and a press 12 suitable for carrying out the method of the present invention. In FIG. 1, components that are operationally or structurally similar to those in FIG. 2 are given the same reference numerals. Mold 10 and press 12 of FIG.
Is Auto-Form Bagwell
Is a typical arrangement of molds 10 and presses 12 found in presses available from NRM manufacturers. Such presses and common mold shapes are widely used within the tire industry.

In FIG. 1, the mold 10 includes a male portion 14 and a female portion 15 which are divided by a dividing line 16. Part 14,
15 is movable in the direction perpendicular to the dividing line 16 so that one is separated from the other. Mold 10 is tread portion 1
9, 20, side wall portions 23 and 24, bead portion 27,
And 28. As shown in FIG. 2, the bead portions 27 and 28 are defined by bead rings 45 and 47.

In FIG. 1, the tire is not shown for clarity of illustration of the mold 10. Similarly, the bag is not shown for clarity. In the mold embodiment of FIG. 1, some bag is held in the press using bag hole 61. The spider 63 and the plurality of sector plates 65 cooperate to hold the bead ring 45.

The tread portions 19,20, the side wall portions 23,24 and the bead portions 27,28 cooperate to define a molding surface 35. Molding surface 35 is optionally configured in a known manner to enclose mold cavity 37. As in FIG. 2, the mold 10 is closed when the mold 10 is closed.
When the bladder is expanded against the inner surface of the tire contained therein, the bladder will shape the tire while heat is supplied to the tire mold 10 which typically acts to cure the bladder and the tire. It acts to urge the mold to form.

Aligning the portions 14, 15 of the mold 10, preferably along the parting line for closure, is facilitated by providing a plurality of dowel pin assemblies 69 circumferentially surrounding the mold cavity 37 along the parting line 16. It is supposed to be.
Each mold portion 14, 15 has a shoulder 70 formed to mate with a hole 71. The dowel bush 72 and dowel pin 73 are received in the holes 71 and retained by the through fasteners 74 on the shoulder 70. Fasteners 74 can be of any suitable or conventional type, such as mechanical screws that abut shoulder 75.

At least one vacuum conduit means 52 is provided in the portion 15 and connects between the parting line and a location external to the mold for air transfer. A vacuum system (not shown in FIG. 1) is interconnected to evacuate through vacuum conduit means 52. The interconnection between the vacuum conduit means 52 and the vacuum means can be of any suitable or conventional form, such as a manual or solenoid operated valve.

A parting line keyway 80 is provided in one of the portions 14,15. The covering seal material 81 is provided and formed so as to be receivably received in the keyway 80. Ring clamp 82
Is formed so as to compress the covering sealing material 81 so that it can be retained in the key groove at the time of fastening. Desirably, the covering seal material 82 has a sloped portion 83, which covers the chamfered or rounded portion 84 provided adjacent to the outer edge of the parting line 16 on the mold portion 14. Make it easier. The coated sealant 81 may be made of any suitable or conventional elastomeric material, as long as the mold 10 is partially open along the parting line 16, as well as:
It should be formed such that when the mold 10 is completely closed along the parting line 16, a seal can be formed along the parting line 16 between the portions 14,15. The sealing material 81 is formed along the parting line 16 into the mold parts 14, 1
The air path entering the mold cavity 37 along the parting line 16 is substantially in the initial position where the mold 10 is open within a range of between about 0.10 cm and about 5.08 cm when measured vertically between the five. It is desirable to prevent it.

Suitable or conventional materials that can be used to make the coated seal 81 in FIGS. 1 and 2 are fluorocarbon rubbers such as Viton rubber and Kel F rubber, resin cured butyl rubber, silicone rubber and phenolic cured butyl rubber. , All of which are commercially available. A lubricant such as oil and / or graphite may be used to extend the seal life.

The opportunity for air to move from outside the mold cavity 13 to the mold cavity 37 is along the interface 90 between the bead ring 45 and the mold portion 14, and
It also exists between the bead ring 47 and the mold part 15. The bead ring 45 in the embodiment of FIG. 1 can move away from the mold part 14, but the bead ring 47 is fixed to the non-rotatable part 15. Interface 90 between mold portion 15 and bead ring 47
Can be sealed along with the rubber that enters along the interface 90 to fill the notch 99 and cure into the notch during the first tire cure. Hardened rubber is mold 1
It remains in the notch 99 during the subsequent curing that is achieved in 0.

The boundary line between the mold portion 14 and the bead ring 45 can be sealed by using the flexible bead seal material 92, which is the bead ring 45.
Is circumferentially surrounded and is retained by the bead ring 45 by the use of a bead ring seal fastener 94.
The bead ring seal fastener 94 may be held to the bead ring in any suitable or conventional manner, such as by using fasteners 95. The bead ring seal 92 is resiliently biased into engagement with a keyway 96 formed in the bead ring 45 and assumes an imaginary position 97 when the bead ring 45 separates from the mold portion 14.

By the seating of the bead ring, the bead ring seal 92 is elastically urged to move away from the virtual position 97 and seal. The bead ring seal 92 can be made of the same material used to form the overseal material 81. The bead ring seal 92 should essentially preclude the complete migration of air from outside the mold 10 into the mold cavity 37 during evacuation and during tire molding. Bead ring 45 before closing the mold
If the seat ring is not seated, the mold opening area where the bead ring seal 92 should not allow air to move into the mold is preferably a mold seal area 81 where the mold seal material 81 is along the parting line 16. It should be the same as the mold opening area to substantially prevent the movement of air in the cavity 37. Preferably, this range is 0.10 cm to 5.08 cm along the dividing line, most preferably between about 1.27 cm and 3.81 cm. Despite being seated, the bead ring seal 92 should function to substantially prevent air movement into the mold cavity 37 when the mold is fully closed.

Referring to FIG. 4, FIG. 4 shows a preferred modification of the bead ring seal 92. The seal 92 is shown in FIGS.
Formed to be received in a notch 96 formed in mold portion 14 instead of being received in a keyway or notch 96 formed in movable bead ring 45 as shown. To be done. Referring to FIGS. 1, 2 and 4, the bead seal shown in each of these figures is
There is one sealing surface 120, which is exposed in the mold cavity 37 via the interface 90 between the moving bead ring 45 and the mold part 14 whenever pressure is present. Opposite surface 122 is exposed to some source of pressure, typically atmospheric pressure surrounding mold 10. Reducing the pressure in mold cavity 37 by drawing a vacuum in mold cavity 37 along parting line 16 by using, for example, vacuum conduit means 52, creates a differential pressure between the pressure at surface 122 and the pressure at surface 120. Increase and press the seal 92 more firmly into a sealing contact. Such seals are often self-acting, that is,
It is said to be able to sit more firmly when the pressure differential between the surfaces 120, 122 increases.

Similarly, the encapsulant 81 has a surface 126 along the parting line 16 that is exposed to the pressure in the mold cavity and some source of pressure, typically the opposite surface 126 that is exposed to the atmospheric pressure surrounding the mold. . Bead ring seal 92
By providing a vacuum to the mold cavity 37 via the parting line 16 results in a reduced pressure on the surface 124 of the coated seal 81, and the pressure differential between the surfaces 124, 126 effectively biases the coated seal 81. The sealing material 81 is more firmly brought into sealing contact with the mold portion 14.

The sealing material 81, 92 is sufficiently urged by the pressure differential created between the surfaces 124, 126, 120, 122 during vacuum evacuation of the mold to permit elastic movement to achieve a tight seal. It should have elasticity.
On the contrary, it is important that the sealant is not elastic so that it may be sucked into the parting line 16 or the interface 90 under the influence of the pressure difference between the surface pairs 120,122 and 124,126.

Referring to the drawings, FIG. 5 shows a modification of the seal geometry for use in sealing between the lower bead ring 45 and the mold portion 14. The recess 96 is formed in the mold portion 14, but it may be formed in the lower bead ring 45. A hollow tubular seal 130 is received in the recess 96. The seal 130 has an outer surface 132, the outer surface 132
132 is exposed to the pressure in the mold cavity 37 and on the inner or opposite surface 134. The opposite surface 134 defines a tube within the seal. This tube is a pressure fluid,
Liquid or air pressure is typically applied. When the mold cavity 37 is evacuated, the differential pressure within the mold cavity provided by the surface 132 through the interface 90 decreases with respect to the pressure provided by the opposite surface 134, thus expanding the sealant. To make a sealed contact. Although not essential, it is often desirable that the tube defined by the opposite surface 134 be expandable by using liquid or gas pressure in a known manner. Alternatively, the seal may be expanded by thermal expansion of the fluid in the tube or the presence of springs such as coil springs or rubber O-rings in the tube.

Referring to the drawings, FIG. 7 shows a radial opening mold 10 and a mold press 12 in which the present invention can be realized.
Is shown. The mold 10 has a mold portion or plates 14 and 15. The mold plates 14 and 15 are divided at the dividing line 16. The upper mold plate 14 has a tread ring portion 19, a side wall portion 24 and a bead ring portion 28. The bead ring portion 28 is integral with the mold portion 14. The mold portion 15 has a bead ring portion 27 formed by the movable bead ring 45 and a side wall portion 23.

The mold portions 14, 15 define a mold surface 35. A mold cavity 37 is created in the mold 10 when the mold is closed. The bag 39 is retained in the mold cavity 37 in any suitable or conventional manner, and
It acts to form the outside of the tire 30 that is received by the mold against the mold surface 35.

The press 12 has a top platen support 150 and a plurality of actuator ring portions 155, one or more of which may optionally have a steam chamber 156 that heats the actuator ring component 155. You may. The interface between top platen support 150, top platen 152 and actuator ring component 155 should be sealed by the use of suitable or conventional gasket O-rings or the like (not shown).

The press 12 also includes a press base 160. The press base supports the bottom platen 162. The platen 162 has at least one steam chamber 164 that can heat the bottom platen. The bottom platen 162 supports the mold part 15.

The mold portion 14 is supportably carried by a mold adapter ring 158 having an elongated shaft portion 170. The shaft portion 170 is slidably received in the bush 171. Bush 171 is supported by top platen support 150. The pair of O-rings 172 and 174 are the top platen support 1
Between 50 and bush 171, as well as bush 171 and shaft part
It acts to seal between 170 and. Between the top platen support 150 and the bush 171, and between the bush 171 and the shaft portion 170, it is substantially impossible to enter the mold cavity 37 along the boundary surface from a position outside the mold. .

The parting line seal 81 is received in a keyway 80 formed in the molded part 15. The seal 81 is formed so as to surround the mold in the circumferential direction. It acts to hold the band fastener seal 81 in the keyway 80. Optionally, the seal 81 has a beveled portion 83 to facilitate sliding engagement of the mold part 14 with the tread part 19. The seal 81 has a pressure-exposed surface 126 outside the mold cavity 37 and a pressure-exposed surface 124 inside the mold cavity 37, which results in the evacuation of the mold cavity 37, resulting in surfaces 124, 126.
The pressure difference between them increases, and the seal 81 is urged to make a tighter sealing contact with the tread part 19 of the mold part 14.

The self-actuating seal 92 is releasably received in a keyway 96 formed in the movable bead ring 45. The seal 92 has a surface 122 exposed to pressure outside the mold cavity 37 and a surface 120 exposed to pressure inside the mold cavity 37. Evacuation of the mold cavity 37 creates a pressure differential across the surfaces 122, 120, which results in the seal 92 being more strongly biased against the mold portion 15 into sealing contact.

Vacuum conduit 52 is formed through mold part 15, bottom platen 162 and press base 160. The vacuum conduit has a boundary or intersection 53 with the parting line 16.

Referring to the drawings, FIG. 3 is a schematic illustration of an evacuation system 140 suitable for use in practicing the present invention. Vacuum system 140 has a vacuum source 141, which may be any suitable or conventional means such as a conventional vacuum pump, ejector, or jet. The evacuation system 140 includes a valve 142, which shuts off the mold vacuum conduit means 52 to the vacuum system 140. The system 140 has an exhaust valve 143 through which the vacuum conduit means 52 is evacuated. The valve 144 intermittently connects the vacuum source 141 to the vacuum system 140.

Multiple accumulators 145, 146, 147 are valves 148, 14
By using 9,150, it can be connected to the vacuum source 141.

The accumulator 147 is evacuated to a desired vacuum by opening the valve 144 and the valve 150 and operating the vacuum source 141 with the valve 142 in the closed position. In a similar manner, the accumulators 146, 145 will close the desired vacuum valves 148, 149, 150 and the valve 144 and then the valve 142.
Is the mold cavity 3 through the use of vacuum conduit means 52.
It can be opened for a desired vacuum of 7. Valve 14
8 is then opened to evacuate a substantial portion of the air from mold cavity 37. The valve 148 is then closed and the valve 149 is opened to evacuate more air from the mold cavity 37 of FIGS. 1, 2 and 7. Vacuuming at such a stage allows a very high vacuum level to be reached quickly compared to a vacuum pump of the simple wait and catch type. The valve 149 is then closed and the valve 150 is opened to allow air remaining in the mold cavity 37 to accumulate in the accumulator 14.
Vacuumed to 7. The valve 142 is then closed and the process of evacuating the accumulators 145, 146, 147 is restarted by the use of the vacuum source 141.

Table I. Describes the structure of the process used to evacuate the mold cavity after the actuator has been evacuated.

Vacuum should be completed within almost 55-60 seconds,
Preferably completed within 45 seconds, most preferably about 10 to
Complete within 15 seconds. The accumulators 145, 146, 147 and the vacuum conduit means 52, which provide the vacuum to the mold cavity 37, should be at least within 1 minute, preferably within 45 seconds.
It should be shaped to allow vacuuming of mold cavity 37 to a pressure not exceeding 16932 Pa, preferably not exceeding 8466 Pa. More preferably, the vacuum is completed within about 15 seconds to a pressure of less than 8466 Pa, more preferably less than 6600 Pa, and most preferably less than 2000 Pa. These pressures remove sufficient air from the mold cavities 37 so that the final cured tire will properly mold surface 35.
And is required to ensure that the cured tire in the mold does not insulate the curing process in an insulating manner.

1, 2 and 7, the tread and sidewall components 19, 20, 23, of the mold 10 to escape air trapped within the mold when the mold is closed.
It is important to note that there is no provision for degassing the mold via a conventional degassing passage formed through 24. Instead, the present invention uses a vacuum connected to vacuum conduit means 52 to rapidly and deeply air the mold cavity 3 in preparation for the start of the tire building operation.
Evacuate from 7. The tire building process using vacuum evacuation of the mold cavity begins as a molding process with the formation of an unvulcanized tire. Unvulcanized tires are formed in a well known manner from rubber and other components called uncured or unvulcanized at the center of gravity of the tire building machine. Typically, for radial tires, unvulcanized tire building machines have building drums to which tire liners and tire body plies are applied. The material overlying the drum is rolled down and the bead assembly is applied to the edge of the forming drum. The overlapping plies are then rolled up over the bead package and back onto the forming drum. The protruding rubber sidewall is applied to the tire ply and the debris is expanded to the desired diameter. A stiffening belt is then applied, a protruding tread is applied over the belt, and any air trapped between the belt and the tread is removed by any suitable or conventional method, such as a task called stitching. It The tire is now ready for vulcanization or curing.

Referring to FIGS. 1 and 2, the mold is opened by moving the parts 14, 15 away from the parting line 16. As a result, the unvulcanized tire 0 is placed in the mold cavity 37. Once the unvulcanized tire 30 is placed in the mold cavity 37, the bag 39 can expand the bag to fill the tire at approximately 6895 Pa and 6894 Pa.
Or expanded with low pressure or forming steam having a gauge pressure of higher.

The press is then closed until the mold sections 14, 15 are separated by between about 0.10 cm and 5.08 cm when measured in a direction perpendicular to the parting line 16 between the mold sections 14, 15. , And preferably at positions where the mold portions 14, 15 are separated by between about 1.91 cm and 3.81 cm when measured perpendicular to the parting line 16, and most preferably 2.54 cm and 3.
It is closed to a position separated by 18 cm. The gauge pressure of forming vapor supplied to the bladder 39 is then reduced to between about 6800 Pa and about 41000 Pa, and vacuum is applied to the mold cavity through the vacuum conduit means 52 along the parting line 16.

Preferably, the vacuum source comprises a plurality of accumulators as shown in FIG. 3, accumulators 145,
The vacuum from 146, 147 is continuously applied to the mold cavity 37, that is, the absolute pressure in the mold cavity 37 is 16932 Pa or less, preferably 864
The pressure is rapidly reduced to a pressure of 4 Pa or less, more preferably 6600 Pa or less, and most preferably 2000 Pa or less. During vacuum evacuation of the mold, the seals 81, 92 must be tightly engaged, essentially disabling any movement of air from a location external to the mold cavity 37. Failure to prevent such air movement will result in insufficient vacuuming of the mold cavity,
This results in defective surfaces or so-called light tires being created as a result of the curing process.

The mold 10 is then fully closed and the cure cycle begins. The seals 81, 92 continue to essentially prevent any movement of air from outside the mold 10 into the mold cavity 37 when the mold 10 is closed and while the mold 10 remains closed. There must be. The tire then undergoes a hot water cure or a so-called steam cure. Under vapor curing, the bag 39 is about 1379-
It is filled with steam at a gauge pressure of 1742 kPa for about 15 minutes, after which the steam is reduced to atmospheric pressure and a vacuum is applied to collapse bag 39. The press 12 is opened, and the now curable components of which are cured or so-called vulcanized tires are removed.

When warm water curing is used, the bag 39 is approximately 1379 to 1724 kP
It is filled with high-pressure steam of a for about 2 minutes, and then high-pressure hot water is passed through the bag body 39 at a pressure of about 1724 to 2578 kPa and a temperature of about 198 ° C. for a time of 10 minutes and 14 minutes. Is circulated. The warm water in the bag 39 is then removed and replaced with high-pressure steam for about 2 minutes, and then the steam contained in the bag 39 is reduced to atmospheric pressure and a vacuum is applied to crush the bag 39. . The press is opened and the cured or so-called vulcanized tire is then removed.

The resulting tire of the practice of the present invention is a so-called air vent or vent when removed from a mold cavity, or generally from the tire sidewall portion, tread portion and bead portion to the outside of the tire contour. The tread portion 19 of the tire mold 10,
It is characterized by the absence of protrusions resulting from the presence of cured rubber provided in 20, the sidewall portions 23, 24 and the bead portions 27, 28. The absence of such protrusions necessitates placing the tire on a tire finishing machine and trimming the tire in order to prepare the tire for sale,
It eliminates the need for cutting or the like to remove such protrusions, and results in a savings of about one ounce of unvulcanized rubber per tire manufactured. This is because it is not necessary to allow the unvulcanized tire produced to contain excess rubber to allow the unvulcanized rubber to enter the vents of the tire mold and cure therein. The cured tire that is removed from the mold after being formed by the method of the present invention is particularly sharp as the unvulcanized tire closely conforms to the contours of the mold cavity 35 of the tire mold 10 as a result of substantially complete air removal. And a tread profile.

The desired vacuum is within a relatively short time and the mold cavity 3
Must be achieved within 7. Desirably, the desired vacuum is achieved within about 60 seconds, and more preferably within about 45 seconds. Most preferably, the vacuum is achieved within 30 seconds, and is typically desirable if a multi-stage vacuum system such as that shown in Figure 3 is used to vacuum the mold. The vacuum is achieved in about 6 to 15 seconds.

If the time to achieve the vacuum in the tire mold is extended,
And, in particular, if these times exceed about 60 seconds, the pressure of the bag body tends to result in an excessive shape of the tire, which is tightened when the mold is closed and causes a defective shape. . Further, when the evacuation time exceeds 60 seconds, the bag body is crushed, and the vapor pressure in the bag body is reduced during evacuation to prevent excessive shape. Note that an excessively long period for achieving vacuuming of the mold cavity 37 causes the rubber to enter the parting line 16, which causes a groove in the mold cavity 37 at least partially having a poor seal to remain. It will lead to the vacuum system. Finally, during excessively long vacuuming times, the tire may be partially cured before the mold is completely closed, especially in areas that are sensitive to curing, such as sidewall portions. This is because the amount of curable elastomer rubber in the side wall portion is relatively limited as compared with the tire tread.

In practicing the present invention, one important point is the relatively free and rapid air movement from the mold cavity 37 to the vacuum conduit means 52 for transfer to the vacuum system 140. If the mold 10 is over-closed along the parting line, especially if it is closed to an opening width of less than 0.10 cm, the free movement of air to the vacuum conduit means 52 is substantially limited and the evacuation time is reduced. Can be too long. Further, upon closure of the mold to a parting line opening of less than about 0.10 cm, the tire tread portion 19, 20 and sidewall portion 23 of the mold under the force of the expanded bladder and the substantially closed mold. , 24 and bead portions 27, 28 to expand the trapped air, making it very difficult to prevent the trapped air from being evacuated from the mold. The result is a light tire.

In preparation for tire vulcanization, the final spread that the mold remains open along the parting line 16 during evacuation of the mold cavity 37 is the seal 81,
92 is the mold cavity 3 from outside the mold.
7 substantially depends on the possibility of blocking the movement of air. In practice, this limitation precludes mold openings larger than about 5.08 cm, but the possibility of a suitable seal shape will allow the mold cavity to be evacuated sufficiently quickly to allow molding to be performed. Some excess over about 5 cm of mold opening is acceptable as it prevents overstressing of the vulcanized tire and also prevents migration of unvulcanized elastomeric tire component material into the parting line 16. . The vacuum conduit means 52 is sized and shaped according to conventional plumbing connections. That is, typically, the vacuum conduit means 52
Is formed for connection of 3/4 in or 1 in standard size pipes. A plurality of such vacuums circumferentially spaced around the tire mold 10 with sufficient dimensions provided by the particular number of vacuum conduit means 52 suitable to evacuate the mold cavity in the desired time. Conduit means 52 is considered within the scope of the invention. A stepped system 140 of vacuum evacuation accumulators formed for at least continuous application of vacuum to the tire mold 10 allows a single vacuum conduit means 52 of about 3/4 inch standard size to be evacuated to the tire molding. It turned out to be suitable for achieving. The vacuum conduit means 52 need not be circular in cross section, are desirable for assembly into the mold 10, and may have any other cross sectional shape depending on the internal connection attachment to the vacuum system 140.

As described above, a considerable number of materials are used as the seals 81 and 92.
It can be used for the configuration of. In constructing seals for use in practicing the present invention, it is desirable for the seal to have a service life that is at least equal to the service life possible with bag 39. Therefore, silicone rubber, epoxy-cured butyl rubber, and so-called fluororubber are found to be preferred in the practice of the present invention, as they can provide an extended surface life. It is extremely important that such rubbers exhibit little permanent deformation at any temperature where the mold and bag are heated during tire cure. It is said that the seals 81, 92 should be able to last longer than a substantial permanent set temperature of at least 198 ° C.

Referring to the drawings, FIG. 6 shows an outermost tread 231, a side wall defining a tire 230 having a contour without a protrusion in the form of a vent.
3 shows a tire 230 made according to the present invention emerging from a mold cavity having 232 and beads 233. Trimming of the tire 230 to remove protrusions resulting from the curing of such unvulcanized tire rubber in the mold vent is not necessary. Therefore, since such trimming loss is not caused, the unvulcanized rubber can be saved.

While we have shown and described specific preferred embodiments of the present invention, it will be apparent that various changes may be made without departing from the scope of the claims of the present invention. In particular,
Although the invention has been shown on the basis of the presses of FIGS. 1, 2 and 8, it is immediately applicable to so-called radial opening presses as shown in FIG.

〔effect〕

As described above, according to the present invention, the cavity is evacuated from the position on the dividing line of the tire mold, and the applied pressure and application time of the vacuum at this time are appropriately set. By increasing the sealing ability by using an elastically deformable seal that seals in the circumferential direction, it is possible to efficiently perform tire molding, and the protrusions that were conventionally formed as traces of ventilation holes on the molded tire. Is no longer possible, and tires can be manufactured efficiently.

[Brief description of drawings]

FIG. 1 is a partial side view of a tire mold and a tire molding press according to an embodiment of the present invention, FIG. 2 is a partial side view of a tire mold and a tire molding press according to an embodiment of the present invention, and FIG. Figure 4 is a schematic diagram of a vacuum source used to carry out the method; Figure 4 is a partial side view of a tire mold and tire building press showing an alternative lower bead ring seal; Figure 5 is an alternative lower bead. FIG. 6 is a partial side view of a tire mold and a tire molding press showing a ring seal, FIG. 6 is a perspective view showing a tire made according to the present invention, and FIG. 7 is a part of the tire mold and the tire molding press according to an embodiment of the present invention. It is a side view. 10 ... Mold, 14, 15 ... Mold part (divided body), 30 ... Tire, 37 ... Cavity, 39 ... Bag body, 81 ... Seal.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location B29L 30:00 4F (72) Inventor Donald Labor Tray USA, Ohio 44221, Quia Hoga Folles, 9th Street 1940 (56) References Japanese Patent Publication Sho 33-8540 (JP, B1)

Claims (12)

[Claims] 1. A method of forming an uncured tire having a tread portion, a side wall portion and a bead portion, and then molding the uncured tire in a tire mold, the tire mold defining a cavity. A tire portion having a portion, a side wall portion and a bead portion, the mold portion basically having no air holes leading from the inside of the cavity to a point outside the mold, and the tire mold is a circle dividing the mold into a plurality of divided bodies. In the method of molding a tire by having a circumferential dividing line and the dividing body closing the dividing line, an uncured tire is placed in a mold, and 5.08 cm and 0.10 cm are arranged along the dividing line. Partially closes the mold to open a distance in the range, and elastically deformable seal that seals the dividing line in the radial direction outside the tread portion allows air to flow into the cavity along the dividing line. Practically It substantially blocks the inflow of air into the cavity by blocking other passages through which air can enter the cavity, the seal being a strip extending axially and circumferentially. A seal of which one end in the axial direction is supported by the outer periphery of one of the divided bodies of the mold,
The other end of the seal in the axial direction projects from the one divided body and extends toward the outer periphery of the other divided body of the mold, these divided bodies having a distance in the range between 5.08 cm and 0.10 cm. By engaging the outer periphery of the other split body when partially closed and applying a vacuum from a vacuum source to at least one point on the split line in the radial middle of the tread portion and the seal, The cavity is evacuated to an absolute pressure of 16932 pascals or less for a time of about 60 seconds or less, and the seal is designed to increase the airtightness of the seal by evacuating the cavity, thereby completely closing the mold and curing the tire. How to characterize. 2. The method of claim 1 wherein said absolute pressure is less than or equal to about 8466 Pascal and evacuation time is less than or equal to about 45 seconds. 3. At least one bead portion is moveable relative to a side wall portion of one of the mold splits, said method wherein air is present between the bead portion and the side wall portion at least during evacuation of the cavity. 3. A method according to claim 1 or 2 comprising the step of providing a seal formed to substantially prevent flow into the mold at. 4. The method of claim 3 wherein the absolute pressure is less than or equal to about 8466 Pascal and the exhaust time is less than or equal to about 45 seconds. 5. A method as claimed in any one of claims 1 to 4, wherein the dividing line is opened during the exhaust by a distance between 1.27 and 3.81 cm. 6. By providing a plurality of vacuum accumulators and sequentially connecting the accumulators to a conduit, the mold is evacuated before the mold is completely closed but when the mold is sealed to reduce the internal pressure of the mold to 45. Over time within seconds
A method as claimed in any one of claims 1 to 5 comprising the step of bringing the pressure below 8466 Pascals. 7. At least one bead portion movable relative to adjacent sidewall portions and circumferentially between the bead portion and the sidewall portion during the sealing engagement of the parting line seal. Includes a step of sealing between the bead portion and the sidewall portion using a bead seal that seals to a bead seal, wherein the bead seal has one sealing surface exposed to the pressure in the cavity and the opposite surface to the outside pressure source of the cavity. A method according to claim 1 wherein the seal is formed such that it is exposed and thereby the vacuum is applied to the mold to urge the seal into a tighter sealing relationship. 8. A method as claimed in any one of claims 1 to 7 wherein the vacuum source and conduit means are formed to evacuate the mold to less than 6600 Pa within 15 seconds. . 9. A tire mold for molding a tire essentially having no sidewall vents, bead vents, and tread vents that project beyond the outermost surfaces of the bead portion, sidewall portion, and tread portion of the tire. The mold has a tread portion, a side wall portion and a bead portion which form a cavity, and the mold is divided into a plurality of divisions by a circumferential dividing line intersecting the outer peripheral surface of the die, and the dividing body closes the dividing line. A tire mold for molding a tire by means of having a mold inner surface consisting of a bead portion, a tread portion and a side wall portion which does not have a ventilation outlet for letting out a fluid from the inside of the cavity, and has a radius larger than that of the tread portion. At least one conduit means communicating a point on the parting line outside in the direction with the vacuum source, said conduit means being in disconnectable communication with said vacuum source. The conduit means and the vacuum source are configured so that the cavity can be evacuated to an absolute pressure of 16932 Pa or less by applying a vacuum pressure of 60 seconds or less in a state where the mold is sealed, and an elastically deformable seal for dividing line is provided, The seal is a band-shaped seal having a width in the axial direction and extending in the circumferential direction,
One end portion of the seal in the axial direction is supported by the outer peripheral portion of one of the divided bodies of the mold, and the other end portion of the seal in the axial direction of the seal projects from the one divided body to the outer peripheral portion of the other divided body of the mold. Extending towards each other and engaging the outer circumference of the other split when these splits are partially closed at a distance in the range between 5.08 cm and 0.10 cm, and this sealing arrangement allows the exhaust of the cavity to be exhausted. During which the seal is substantially airtight, the seal being capable of substantially preventing air from flowing into the cavity in the partially closed state, and the seal being in the mold joining operation and during the joining operation. A tire mold characterized by being configured so as to continue to prevent the inflow of the air later. 10. A bead for which at least one bead portion is movable with respect to an adjacent side wall portion and which seals between the bead portion and the side wall portion along an outer periphery in a state where the dividing line seal is sealed. An elastic seal is provided, and the bead seal is fixed to one of the bead portion and the side wall portion and has a sealing surface that receives pressure inside the cavity and an outer surface that receives pressure outside the cavity. 10. The tire mold according to claim 9, wherein the airtight sealing property of the seal is enhanced during the exhaust of the cavity. 11. A tire mold according to claim 9 including a vacuum source having a plurality of accumulators formed for continuous interconnection to conduit means. 12. A tire mold according to claim 9 wherein the vacuum source and conduit means are formed to evacuate the mold to less than 8466 Pa within 45 seconds.