JP2009090501A - Method for preheating vulcanizing mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the defective appearance of a vulcanized tire by preventing the direct contact between a bladder 43 and a vulcanizing mold 35 during preheating. <P>SOLUTION: Since upper and lower separation sheets 50 and 51 are made to intervene between the bladder 43 and an upper mold 21 and between the bladder 43 and a lower mold 15, respectively, the profiling surfaces 22 and 16 of the upper and lower molds 21 and 15 are prevented from being contacted with the bladder 43. Since a cylindrical bladder 43 is used, even when the bladder 43 is crushed vertically into a disk during the preheating, its peripheral surfaces are made approximately parallel to each other to be prevented from outstandingly protruding outside in the radial direction, so that the direct contact with the profiling surface 34 of a sector mold 33 is prevented. As a result, the transfer of the pattern of the bladder 43 to the profiling surfaces 22, 16, and 34 from the bladder 43 is prevented during the preheating. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

    The present invention relates to a preheating method for preheating a vulcanization mold to a temperature suitable for vulcanization after replacement of the vulcanization mold.

    In general, when the type of tire to be vulcanized is changed, the vulcanization mold and bladder in the vulcanizer are replaced with one corresponding to this change. Since it has been stored at the storage station for a long time, the temperature has dropped to room temperature. As a result, when trying to vulcanize an unvulcanized tire using a vulcanization mold having a low temperature after replacement of the vulcanization mold or the like, it becomes difficult to control the degree of vulcanization at the time of vulcanization of the first unvulcanized tire, As a result, the first unvulcanized tire could not be properly vulcanized and had to be discarded.

In order to solve such a problem, conventionally, for example, what is described in the following Patent Document 1 has been proposed.
JP 10-006345 A

  Before the replacement work, the next-use vulcanization mold is placed on a heating plate and preheated by the heating plate, and the pre-heated next-use vulcanization mold and the used vulcanization mold are After the replacement, the unvulcanized tire is vulcanized using a vulcanization mold for the next use in which preheating remains.

    However, even if vulcanization is performed by replacing the vulcanization mold that has been preheated in this way, a certain amount of time elapses between the time when the vulcanization operation is started and the time when the vulcanization operation is started. For this reason, the temperature of the vulcanization mold decreases unevenly due to heat radiation, and as a result, there is a problem that preheating is insufficient for proper vulcanization. In addition, in order to preheat the vulcanization mold to be used next, a heating plate for preheating is required, and there is a problem that the entire apparatus becomes complicated and expensive.

  In order to solve such problems, for example, after replacing the vulcanization mold or the like with the next use, the vulcanization mold is closed, and the closed vulcanization mold is disposed in close contact with the vulcanization mold. The heated plate is heated from the outside by supplying a heated fluid until just before the unvulcanized tire is brought into the vulcanization mold, while the low pressure is heated until just before the unvulcanized tire is brought into the vulcanization mold inside the bladder. It is also conceivable to heat from the inside by supplying a fluid so that the vulcanization mold is preheated together with the bladder.

  However, if this is done, the bladder is in direct contact with the mold surface of the vulcanization mold during preheating, and the pattern of the bladder is transferred to the mold surface. When vulcanized, the bladder pattern transferred to the molding surface of the vulcanization mold is transferred to the tire, which causes a problem in that appearance defects occur in the vulcanized tire.

  An object of the present invention is to provide a vulcanization mold preheating method capable of preventing appearance defects of a vulcanized tire by preventing direct contact between a bladder and a vulcanization mold during preheating.

    The purpose of this is to supply a heating fluid to the hot plate placed in close contact with the vulcanized mold in a closed state that molds the outer surface of the unvulcanized tire until just before the unvulcanized tire is brought into the vulcanized mold, The vulcanized mold is preheated by supplying a low-pressure heating fluid to the inside of the bladder that presses the unvulcanized tire against the vulcanization mold from the inside during vulcanization until just before the unvulcanized tire is brought into the vulcanization mold. A vulcanization mold preheating method, wherein the bladder is a cylindrical one whose outer diameter at the end of molding is substantially the same diameter from one axial end to the other axial end, and In addition to preventing the direct contact between the bladder, the upper mold, the lower mold, and the lower sidewall portion molding surface between the upper mold and the lower mold. By interposing it can be achieved.

  In the present invention, the lower separation sheet is used to prevent direct contact between the bladder and the upper mold, the lower mold, and the lower sidewall portion molding surface between the bladder and the vulcanization mold. Therefore, the transfer of the pattern from the bladder to the vulcanization mold (upper and lower molds) and to the lower side wall mold surface is prevented from being performed during preheating. Appearance defects in the wall portion are prevented.

  In addition, the bladder supplied with the low-pressure heating fluid is crushed from above and below by the closed vulcanization mold and the upper and lower separation sheets, so that it deforms into a disk shape while expanding the diameter. The cylindrical outer diameter at the end of molding is substantially the same from one end in the axial direction to the other end in the axial direction, so the outer peripheral surface of the bladder remains in the axial direction even after deformation into a disk shape. It becomes almost parallel.

  Here, if the shape at the end of molding is a barrel shape as a bladder, that is, the outer diameter gradually increases from the axial end toward the center in the axial direction, it is deformed into a disc shape as described above. In this case, since the outer peripheral surface is substantially U-shaped in cross section, the central portion of the outer peripheral surface protrudes greatly outward in the radial direction from the outer peripheral surface of the bladder of the present invention, and directly contacts the tread portion molding surface of the vulcanization mold. .

  On the other hand, in the bladder of the present invention, since the low-pressure heating fluid is supplied to the inside, there is almost no expansion due to the elongation of the rubber, and the outer peripheral surface of the bladder is the shaft as described above even in the crushed state. Since it is almost parallel to the direction, no part of the outer peripheral surface of the bladder is in direct contact with the tread portion molding surface of the vulcanized mold, and appearance defects in the tread portion of the vulcanized tire are prevented. The

  According to the second aspect of the present invention, the vulcanization mold can be effectively preheated while strongly preventing the bladder from coming into contact with the tread portion molding surface due to the extension based on the internal pressure. Furthermore, if it comprises as described in Claim 3, 4, a bladder will not be damaged and a lower separation sheet can be manufactured simply and cheaply.

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 11 denotes a vulcanizing device that vulcanizes an unvulcanized tire to obtain a vulcanized tire. The vulcanizing device 11 has a stationary lower base 12, and the lower base 12 includes A lower heating plate (lower platen) 13 to which a high-temperature gas composed of a heating fluid such as steam or inert gas is supplied during preheating and vulcanization is fixed via a heat insulating material 14. The lower heat plate 13 is detachably attached in a state where the lower mold 15 is closely arranged, and the upper surface of the lower mold 15 has a molding surface 16 for mainly molding the lower sidewall portion of the unvulcanized tire. Is provided. As a result, the lower mold 15 is effectively heated by transferring heat from the lower heat plate 13 by heat transfer.

  Reference numeral 17 denotes an upper base installed above the lower base 12 so as to be separated therefrom, and the upper base 17 is paired with the lower base 12. The upper base 17 is connected to a piston rod of a vertical cylinder (not shown). As a result, when the cylinder is operated, the upper base 17 moves up and down. Move closer to and away from the base 12.

  An upper heating plate (upper platen) 20 is fixed to the lower surface of the upper base 17 through a heat insulating material 18 to which a heating fluid such as high-temperature steam or inert gas is supplied during preheating and vulcanization. . Reference numeral 19 denotes a horizontal movable plate disposed immediately below the upper base 17. An upper mold 21 is detachably attached to the movable plate 19, and an upper surface of the unvulcanized tire is attached to the lower surface of the upper mold 21. A molding surface 22 that mainly molds the sidewall portion is provided.

  When the vulcanization mold described later is closed, the movable plate 19 comes into surface contact with the upper heating plate 20. At this time, the upper mold 21 is disposed in close contact with the upper heating plate 20 through the metal movable plate 19. Thus, heat from the upper heating plate 20 is transferred to the upper mold 21 by heat transfer, and the upper mold 21 is effectively heated.

  Reference numeral 23 denotes a piston rod of a vertically extending cylinder attached to the upper base 17, and the movable plate 19 is connected to the tip (lower end) of the piston rod 23. As a result, when the cylinder is operated and the piston rod 23 is retracted or protrudes, the movable plate 19 and the upper mold 21 are moved up and down separately from the upper base 17 and moved closer to and away from the upper base 17. .

  An outer ring 26 is provided so as to surround the movable plate 19 and the upper mold 21 from the outside in the radial direction. The upper end of the outer ring 26 is attached to the outer end of the upper base 17 in the radial direction. An inclined surface 27 is formed on the inner periphery of the outer ring 26. The inclined surface 27 is formed of a part of a conical surface that expands toward the lower base 12. Reference numeral 28 denotes a plurality of, nine arcuate holders arranged side by side in the circumferential direction, and the upper ends of these holders 28 are supported by a movable plate 19 radially outward from the upper mold 21 so as to be movable in the radial direction. ing.

  Further, an inclined surface 30 formed of a part of a conical surface with the same gradient as the inclined surface 27 of the outer ring 26 is formed on the outer periphery of the holder 28, and the inclined surface 30 and the inclined surface 27 are connected by a joint. However, it is slidably engaged. As a result, when the movable plate 19 approaches and separates from the upper base 17 and the distance between them changes, the holder 28 is supported by the movable plate 19 and is synchronized in the radial direction by the wedge action of the inclined surfaces 27 and 30. Moving.

  33 is a sector mold that is detachably attached to the radially inner side surface of each holder 28 and has the same number of arcs as the holder 28. The tread portion of the unvulcanized tire is mainly formed on the radially inner side surface of these sector molds 33. A molding surface 34 for molding is formed. When the sector mold 33 moves to the inner limit in the radial direction together with the holder 28, the sector mold 33 comes into close contact with each other to form a continuous ring shape. At this time, the upper and lower molds 21 and 21 are lowered to the lower limit. 15, the vulcanization mold 35 composed of the upper, lower, and sector molds 21, 15, 33 is closed to form a donut-shaped space for storing the unvulcanized tire inside, and the molding surface 16, 22 and 34 constitute a molding surface 36 for continuously molding the outer surface of the unvulcanized tire.

  1 and 2, reference numeral 38 denotes a vertically extending bug body that is loosely fitted in the central portion of the lower base 12, and this bug body 38 is moved up and down by a fluid cylinder or the like (not shown). A center post 39 coaxial with the bug body 38 is slidably inserted into the bug body 38, and the center post 39 is lifted and lowered separately from the bug body 38 by a cylinder or the like (not shown).

  An upper clamp ring 40 is detachably attached to the upper end portion of the center post 39. The upper clamp ring 40 is positioned between the upper and lower molds 21 and 15, and the upper mold 21 is raised by the center post 39 rising. It can contact | abut to the inner edge part. Further, a rectangular groove-shaped notch 41 extending continuously in the circumferential direction is formed at the upper end portion of the upper clamp ring 40 in the radial direction.

  On the other hand, a lower clamp ring 42 is detachably attached to the upper end of the bug body 38. The lower clamp ring 42 is positioned between the upper and lower molds 21 and 15, and when the bug body 38 is lowered, The lower mold 15 can be pressed against the lower base 12 by contacting the inner end of the mold 15. 43 is a bladder made of vulcanized rubber that can be easily bent and stretched, and the bladder 43 has a shape at the end of molding, in other words, a shape in a free state in which atmospheric air exists. 2 has a Sumiyoshi lantern shape as shown by a solid line in FIG. 2, and has a cylindrical portion 44 larger in diameter than the upper and lower clamp rings 40, 42, and a disk extending radially inward from both axial ends of the cylindrical portion 44. Part 45 and 46.

  Thus, in this embodiment, as the bladder 43, a cylinder having an outer diameter that is substantially the same from the one end in the axial direction to the other end in the axial direction is used. The radial inner end of the disc portion 45 located on one end (upper end) in the axial direction of the bladder 43 is on the upper clamp ring 40, while the radius of the disc portion 46 located on the other end (lower end) in the axial direction is The inner ends in the direction are gripped by the lower clamp ring 42 in an airtight state. Further, a high-temperature and high-pressure heating fluid is supplied into the bladder 43 during vulcanization, and the unvulcanized tire can be pressed against the vulcanization mold 35 from the inside.

  50 and 51 are not used at the time of vulcanization, and are used only at the time of preheating to preheat the vulcanization mold 35, and are the lower separation sheets. Above these, the lower separation sheets 50 and 51 are thin-walled, for example, 0.5 to It has a bowl shape at about 2.0mm and is made of heat-resistant resin. Here, as the heat-resistant resin, it is preferable to use a polyamide resin, particularly nylon, which can be easily and inexpensively manufactured without damaging the bladder 43. Examples of other heat resistant resins include polyamideimide resins, polyphenylene sulfide resins, polyether sulfone resins, and liquid crystal polyester resins.

  The upper separation sheet 50 has a diameter at the boundary 52 between the molding surfaces 16 and 22 for molding the sidewall portion and the molding surface 34 for molding the tread portion of the molding surface 36 of the vulcanization mold 35. On the other hand, the inner diameter thereof is slightly larger than the outer diameter of the side surface (the inner surface in the radial direction) of the notch 41. The upper separation sheet 50 is supported from below by the upper clamp ring 40 with its radially inner end contacting the lower surface of the notch 41 via the bladder 43. Further, the outer diameter of the lower separation sheet 51 is substantially the same as the diameter at the boundary 52, while the inner diameter thereof is slightly larger than the outer diameter of the upper clamp ring 40.

Next, the operation of the first embodiment will be described.
The unvulcanized tire is vulcanized using the vulcanizing apparatus 11 as described above, but the process at this time is well known and the explanation thereof is complicated, and thus the detailed explanation is omitted. Then, when the type of tire to be vulcanized is changed, the vulcanization mold 35 and bladder 43 in the vulcanizing device 11 are replaced with one corresponding to the tire to be vulcanized next. At this time, the container 55 including the movable plate 19, the outer ring 26, and the holder 28 may be replaced together with the vulcanization mold 35.

  Here, since the next use vulcanization mold 35 etc. is stored in the storage station for a long time and the temperature is lowered to room temperature, the vulcanization mold 35 is used for proper vulcanization from the first unvulcanized tire. It is necessary to preheat uniformly to around the temperature during vulcanization. Regarding the bladder 43, since the heat capacity is considerably smaller than that of the vulcanization mold 35, the temperature rises rapidly when vulcanization is started, so there is no problem even if preheating is not performed. Due to the preheating to 35, the bladder 43 is necessarily preheated.

  In this case, the upper base 17 and the like are once raised to the upper limit. At this time, by moving the movable plate 19 with respect to the upper base 17, the sector mold 33 is wedged on the inclined surfaces 27 and 30. It is moved outward in the radial direction synchronously by the action, and is separated from the upper mold 21. Thereby, the vulcanization mold 35 is opened. At this time, the center post 39 is raised, and the fluid is discharged from the inside of the bladder 43. As a result, the outer diameter of the upper and lower ends of the bladder 43 is increased, and the outer diameter of the lower clamp rings 40, 42 is substantially the same. The diameter is reduced to the diameter, and the outer diameter is gradually reduced toward the center in the axial direction, and the bladder 43 is deformed into a drum shape as indicated by a virtual line in FIG.

  Next, the operator manually lowers the lower separation sheet 51 while fitting it on the outside of the bladder 43 and places it on the lower mold 15 (molding surface 16), and then the upper separation sheet 50 is cut out 41. The upper separation sheet 50 is supported from below by the upper clamp ring 40. The state at this time is shown by a virtual line in FIG. Next, when the upper base 17 and the movable plate 19 are lowered, the upper mold 21 comes into contact with the upper clamp ring 40 while the upper base 17 is being lowered. This contact lowers the center post 39. As a result, the upper clamp ring 40 is lowered at the same speed as the upper base 17 while contacting the upper mold 21.

  Next, when the movable plate 19, the upper mold 21, the holder 28, the sector mold 33, and the upper clamp ring 40 are lowered to the lower limit, and the holder 28 comes into contact with the lower heating plate 13 and the lower mold 15, the above-described upper mold Although the lowering of 21 etc. stops, if the upper base 17 is continuously lowered to the lowering limit, the upper heating plate 20 comes into surface contact with the movable plate 19. At this time, since the outer ring 26 descends together with the upper base 17, the sector mold 33 moves synchronously inward in the radial direction by the wedge action of the inclined surfaces 27, 30 to form a continuous ring shape, and the upper and lower molds 21, 15 The vulcanization mold 35 is closed. As a result, the upper heating plate 20 is disposed in close contact with the vulcanization mold 35 in a closed state, specifically, the upper mold 21 via the movable plate 19.

  Then, when the vulcanization mold 35 is closed or before and after it is supplied, a high-temperature and high-temperature heating fluid is supplied to the upper and lower heating plates 20 and 13, and a low-temperature and high-temperature heating fluid is supplied into the bladder 43. Heat from the upper and lower heating plates 20 and 13 and the bladder 43 is transferred to the upper and lower sector molds 21, 15 and 33 by heat transfer to preheat the vulcanizing mold 35 and the bladder 43 to near the vulcanization temperature. To do. Here, the low pressure mentioned above is a pressure that is almost the same as the shape at the end of molding when the heated fluid is supplied to the bladder 43 itself when both ends of the bladder 43 are closed. The pressure is such that almost no elongation occurs.

  At this time, the bladder 43 swells and enters the doughnut-shaped space surrounded by the vulcanization mold 35, but the position is between the upper separation sheet 50 and the lower separation sheet 51. The upper and lower separation sheets 50 and 51 are interposed between the upper mold 35 and the lower mold 21 and 15, respectively. Further, direct contact with the lower sidewall portion molding surfaces 22 and 16 is prevented.

  As a result, the transfer of the pattern from the bladder 43 to the upper vulcanization mold 35 (upper and lower molds 21 and 15) and the lower sidewall portion molding surfaces 22 and 16 during preheating is prevented. The pattern of the bladder 43 transferred to the sulfur mold 35 is not transferred to the unvulcanized tire, and the appearance defect in the sidewall portion of the vulcanized tire is prevented.

  Further, as shown in FIG. 1, the bladder 43, to which a low-pressure heating fluid is supplied, is crushed from above and below by the closed vulcanization mold 35 and the upper and lower separation sheets 50 and 51. However, as the bladder 43, since the outer diameter at the end of molding is substantially the same diameter from one end in the axial direction to the other end in the axial direction, the disc-like shape is used. Even after deformation, the outer peripheral surface of the bladder 43 is substantially parallel to the axial direction of the vulcanization mold 35.

  Here, the shape of the bladder 58 at the end of molding is barrel-shaped as indicated by phantom lines in FIG. 3, that is, the outer diameter gradually increases from the axial end to the axial center. If one is used, even if the pressure of the heating fluid supplied to the inside is low, the outer periphery of the bladder 58 after being deformed into a disk shape when deformed into a disk shape by being crushed from above and below in the same manner as described above. The surface has a substantially U-shaped cross section as shown by a solid line in FIG.

  Thus, when the bladder 58 having the shape as shown in FIG. 3 is used, even when the volume at the end of molding is the same as that of the bladder 43 of the first embodiment, the central portion of the outer peripheral surface of the bladder 58 deformed into a disk shape is It protrudes greatly outward in the radial direction from the outer peripheral surface of the bladder 43 of the first embodiment, and directly contacts the tread portion molding surface 34 of the vulcanization mold 35. As a result, the pattern of the bladder 58 is transferred to the tread portion of the vulcanized tire, resulting in poor appearance.

  On the other hand, in the bladder 43 according to the first embodiment, since the low-pressure heating fluid is supplied to the inside, there is almost no expansion due to the elongation of the rubber, and the outer peripheral surface of the bladder 43 is the above-mentioned even in the crushed state. Thus, no part of the outer peripheral surface of the bladder 43 is in direct contact with the tread portion molding surface 34 of the vulcanization mold 35, and the tread of the vulcanized tire is Appearance defects in the part are also prevented.

  Here, specifically, the pressure of the heating fluid having a low pressure described above is preferably not less than atmospheric pressure and not more than 9.8 kPa (gauge pressure). The reason is that if the pressure is less than atmospheric pressure, the bladder 43 cannot sufficiently enter the donut-shaped space of the vulcanization mold 35, and the preheating of the vulcanization mold 35 may be insufficient, If the pressure exceeds 9.8 kPa, rubber may be stretched in the bladder 43 itself to expand in the radial direction and directly contact the tread portion molding surface 34. This is because the vulcanization mold 35 can be effectively preheated while strongly preventing the contact with the tread portion molding surface 34 due to the elongation based on the stretching.

  In addition, as described above, the heating fluid is supplied to the lower heating plates 20 and 13 and the bladder 43 until just before the unvulcanized tire is carried into the vulcanizing mold 35, whereby the vulcanizing mold 35 and the bladder 43 are provided inside. It is heated from the outside and uniformly preheated to a temperature suitable for vulcanization. Thereafter, the upper base 17 is raised as in the end of vulcanization to open the vulcanization mold 35. At this time, the supply of the heating fluid to the bladder 43 needs to be stopped, but the upper and lower heating plates 20 , 13, the supply of the heating fluid may be stopped, or may be continuously supplied. The preheating time described above may be appropriately determined according to the size, material, etc. of the vulcanization mold 35.

  Next, after quickly removing the upper and lower separation sheets 50 and 51 from the vulcanizing device 11, the unvulcanized tire is carried into the vulcanizing device 11 (vulcanizing mold 35), and then the vulcanizing mold 35 is closed. At the same time, a high-pressure and high-temperature heating fluid is supplied to the upper and lower heating plates 20 and 13 and the bladder 43, and the vulcanized tire is vulcanized by the vulcanization mold 35 whose temperature is increased to the vulcanization temperature. And

    In the above-described embodiment, the vulcanization mold 35 is divided into three parts, and the lower sector molds 21, 15, and 33. In the present invention, the vulcanization mold is divided into two parts and the lower part. You may comprise from a mold. Further, in the above-described embodiment, the present invention is applied to preheating of the vulcanization mold 35 after replacement of the vulcanization mold 35 and the bladder 43. The present invention can also be applied to a case where the vulcanization operation is stopped for a certain period due to a factory stop or the like.

  The present invention can be applied to the industrial field in which the vulcanization mold is preheated to a temperature suitable for vulcanization after the vulcanization mold is replaced.

It is front sectional drawing which shows Embodiment 1 of this invention. It is front sectional drawing of the bladder vicinity. It is front sectional drawing explaining the state at the time of preheating when using the bladder of another shape.

Explanation of symbols

13, 20 ... Hot plate 15 ... Lower mold
16, 22 ... Molding surface 21 ... Upper mold
35 ... Vulcanizing mold 43 ... Blada
50 ... Upper separation sheet 51 ... Lower separation sheet

Claims (4)

    The heating plate is placed in close contact with the vulcanized mold in the closed state that molds the outer surface of the unvulcanized tire, and the heated fluid is supplied until just before the unvulcanized tire is brought into the vulcanized mold. Preheating of the vulcanization mold that preheats the vulcanization mold by supplying a low-pressure heating fluid to the inside of the bladder that presses the tire against the vulcanization mold from the inside until just before carrying the unvulcanized tire into the vulcanization mold. The method uses a cylindrical cylinder having an outer diameter that is substantially the same from one end in the axial direction to the other end in the axial direction as the bladder, and the bladder and the vulcanization mold. In addition to preventing the direct contact between the bladder, the upper mold, the upper mold, and the lower sidewall portion molding surface between the lower mold and the lower mold Preheating method of the vulcanization mold according to symptoms.     The preheating method for a vulcanization mold according to claim 1, wherein the pressure of the heating fluid having a low pressure is not lower than atmospheric pressure and not higher than 9.8 kPa.     The vulcanization mold preheating method according to claim 1, wherein the upper and lower separation sheets are made of a heat resistant resin.     The vulcanization mold preheating method according to claim 3, wherein the heat resistant resin is a polyamide resin.

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