How to clean vulcanization molds

Abstract

To provide a cleaning method for a vulcanizing mold that can reduce the time and cost required for cleaning by removing the dirt adhering to a molding surface while ensuring the releasability of it.SOLUTION: Dirt X adhering to a release agent layer 12 covering a molding surface 13 of a mold 10 is removed together with a surface layer 12a of the release agent layer 12 by scraping the release agent layer 12, leaving the release agent layer 12 remaining and exposing a surface of the release agent layer 12 after removal of the surface layer 12a as a new surface layer 12b.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for cleaning a vulcanization mold, and more particularly to a method for cleaning a vulcanization mold that can remove adhering dirt while ensuring the releasability of the molding surface of the vulcanization mold, thereby reducing the time and cost required for cleaning. [Background technology]

[0002] When manufacturing rubber products such as tires, vulcanization molds are used to vulcanize unvulcanized rubber members. In tire manufacturing, a tire vulcanization bladder is inflated inside a green tire placed in a tire vulcanization mold, and the green tire is pressurized and heated to be vulcanized. Unwanted dirt adheres to the molding surface of this mold as the vulcanization is repeated, and as the dirt increases, it affects the appearance quality of the vulcanized tire. For this reason, the vulcanization mold is cleaned to remove dirt from the molding surface after it has been used for a certain period of time or a certain number of times (see, for example, Patent Document 1).

[0003] The molding surface of the mold may be covered with a release agent layer to prevent adhesion with the outer surface of the vulcanized tire. When cleaning such a mold, dirt adhering to the molding surface (surface of the release agent layer) is removed, and then a release treatment is performed to cover the molding surface with a new release agent layer to ensure releasability. This cleaning method requires a lot of time and cost because it involves a process of removing dirt from the molding surface and a subsequent release treatment process. Therefore, further ingenuity is required to reduce the time and cost required for cleaning, remove dirt, and ensure the releasability of the molding surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-149603 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method for cleaning a vulcanization mold, which can remove adhering dirt while ensuring the releasability of the molding surface of the vulcanization mold, thereby reducing the time and cost required for cleaning. [Means for solving the problem]

[0006] In order to achieve the above object, the method for cleaning a vulcanization mold of the present invention comprises the steps of: Base surface of A vulcanization mold coated with a release agent layer. and removing dirt that adheres to the surface of the release agent layer when vulcanizing unvulcanized rubber. In the cleaning method, the dirt is a component of a rubber composition forming the unvulcanized rubber, By scraping the release agent layer, Without scraping the surface of the base material Together with the surface layer of the release agent layer The above The method is characterized in that the dirt is removed, leaving the release agent layer and exposing a new surface of the release agent layer. Effect of the Invention

[0007] According to the present invention, the dirt adhering to the release agent layer covering the molding surface of the mold is removed together with the surface layer by removing the surface layer of the release agent layer. Then, after removing the surface layer, the release agent layer is left. Therefore, the surface of the molding surface is in a state where dirt is removed and the state where it is covered with the release agent layer is maintained, so that releasability is ensured. Accordingly, the mold can be used repeatedly by utilizing the existing release agent layer, so that the time and cost required for cleaning can be reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is an explanatory diagram illustrating a tire vulcanization mold as viewed from the front. [Diagram 2] FIG. 2 is an explanatory diagram illustrating the tire vulcanization mold of FIG. 1 in a plan view. [Diagram 3] 3 is an explanatory diagram illustrating an enlarged vertical cross-sectional view of a portion of the molding surface of FIG. 2. [Figure 4]FIG. 2 is an explanatory diagram illustrating a cleaning device for a tire vulcanization mold in a plan view. [Diagram 5] 5 is an explanatory diagram illustrating, as viewed from the front, a state in which the nozzle in FIG. 4 is moved along the molding surface while cleaning the molding surface. FIG. [Figure 6] 5 is an explanatory diagram illustrating a state in which the nozzle in FIG. 4 is moving along the molding surface while cleaning the molding surface, as viewed from the side; FIG. [Figure 7] 4 is an explanatory diagram illustrating the molding surface in a state where the dirt in FIG. 3 has been removed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the method for cleaning a vulcanization mold of the present invention will be described based on the embodiment shown in the drawings.

[0010] 1 to 3, one surface of a vulcanization mold 10 (hereinafter referred to as mold 10) is a molding surface 13 for forming the surface shape of a tire. This mold 10 is a sector mold for vulcanizing pneumatic tires, but it may also be a side mold for vulcanizing the side portion of a tire. In addition, the mold may be a mold for vulcanizing other types of tires, not limited to pneumatic tires, or a mold for vulcanizing rubber products other than tires.

[0011] A tire groove forming portion 14 for forming tire grooves protrudes from the molding surface 13. A dashed-dotted line CL in the drawing indicates the center position in the width direction of the mold 10. Also, in the drawing, an arrow W indicates the tire width direction, an arrow R indicates the tire radial direction, and an arrow C indicates the tire circumferential direction.

[0012] The molding surface 13 of the mold 10 to be cleaned in the present invention is coated with a release agent layer 12. Since the base material of the mold 10 is formed of metal, the base surface 11 is metal. Areas other than the molding surface 13 of the mold 10 are not coated with the release agent layer 12, and therefore the base surface 11 is exposed as is.

[0013] The release agent forming the release agent layer 12 has the function of preventing adhesion between the base surface 11 of the mold 10 and the vulcanized tire, and allowing the tire to be smoothly released from the mold 10. The release agent layer 12 is formed from a known release agent such as a fluororesin or silicone. The thickness of the release agent layer 12 varies depending on the size of the tire to be vulcanized, but is generally about 10 μm to 200 μm, for example.

[0014] In this embodiment, the thickness of the release agent layer 12 is equal to or greater than a general thickness, for example, 100 μm or more. The upper limit of the thickness of the release agent layer 12 is, for example, 500 μm.

[0015] When the mold 10 is repeatedly used to manufacture tires by vulcanizing a green tire, dirt X gradually adheres to the surface of the molding surface 13 (release agent layer 12) and the amount of dirt X adheres gradually increases. The dirt X is a rubber composition (a component of the rubber composition) that forms the green tire. As the amount of dirt X adheres increases, the mold 10 adheres more strongly to the vulcanized tire, making it difficult to peel the mold 10 from the tire. In addition, unevenness caused by the dirt X is formed on the inner surface of the vulcanized tire. In the figure, the shaded area indicates the dirt X, and the release agent layer 12 and the dirt X are drawn to be exaggerated and thick.

[0016] The inventors of the present application analyzed many molds 10 with dirt X attached thereto, and found that, under the same conditions of use, the amount (accumulation amount) of dirt X increases according to the number of times of use, but the release agent layer 12 does not wear out significantly and its thickness remains almost the same. It was also found that, under the same conditions of use, the degree of accumulation of dirt X is substantially the same even if the thickness of the release agent layer 12 is different.

[0017] Therefore, in the present invention, the molding surface 13 of the mold 10 is cleaned, for example, after the mold 10 has been used for a predetermined period or a predetermined number of times. During cleaning, the release agent layer 12 is scraped off to remove the surface layer 12a of the release agent layer 12 and the dirt X adhering to the surface layer 12a. The release agent layer 12 is left to remain, and a new surface of the release agent layer 12 is exposed as a new surface layer 12b. In the figure, the dirt X is scattered (dotted), but the degree of adhesion of the dirt X varies, and it may adhere in the form of a thin film over a wide area.

[0018] An example of a procedure for cleaning the mold 10 is as follows.

[0019] 4, the cleaning device 1 used in this embodiment includes a freely movable arm 3, a processing head 2 held at the tip of the arm 3, a nozzle 2a installed on the processing head 2, a processing medium supply source 7 connected to the processing head 2 via a pipe or cable, a booth 5, and a control unit 8 that controls the movement of the arm 3 and the supply amount of processing medium M from the processing medium supply source 7. Also included is a distance sensor 6 that detects the distance from the tip of the nozzle 2a to the opposing surface (release agent layer 12). The rear end of the arm 3 is rotatably connected to a base 4.

[0020] When sand is used as the processing medium M and sandblast cleaning is performed, sand is stored in the processing medium supply source 7 and pressure-fed to the processing head 2 (nozzle 2a) via a pipe. When plasma cleaning is performed when the processing medium M is used as plasma, gas for generating plasma is stored in the processing medium supply source 7 and pressure-fed to the processing head 2 (nozzle 2a) via a pipe. When laser light cleaning is performed when the processing medium M is used as laser light, the processing medium supply source 7 is a laser light oscillator, and the laser light is sent to the processing head 2 (nozzle 2a) via an optical fiber cable.

[0021] The mold 10 is installed inside the booth 5, and the area other than the molding surface 13 is covered by a protective material 9 that blocks the treatment medium M. The treatment head 2 and the nozzle 2a are moved to a desired position inside the booth 5, and the treatment medium M is supplied (sprayed or irradiated) to the surface of the release agent layer 12 so as to cover the entire area of ​​the molding surface 13. The treatment medium M is not limited to being supplied while the mold 10 is kept stationary, and the treatment medium M can also be supplied while the mold 10 is moving.

[0022] 5 and 6, the movement of the arm 3 can be controlled along the molding surface 13 based on the external shape data of the molding surface 13, or it can be moved manually. In this embodiment, the area covered by the protective material 9 is protected from the treatment medium M because the treatment medium M being supplied is blocked.

[0023] By supplying (spraying, irradiating) the treatment medium M to the surface of the release agent layer 12 for an appropriate cleaning time, a thin surface layer 12a of the release agent layer 12 is removed as illustrated in Fig. 7. The type of cleaning is not limited to sandblast cleaning, plasma cleaning, and laser light cleaning, and for example, an abrasive such as a brush or file can be attached to the tip of the arm 3 to remove the surface layer 12a. The thickness of the surface layer 12a to be removed varies depending on the type of cleaning, and is, for example, about 20μ to 50μm.

[0024] As a result, the dirt X adhering to the release agent layer 12 is removed together with the surface layer 12a. Accordingly, the surface of the release agent layer 12 after the surface layer 12a is removed is exposed as a new surface layer 12b, and the cleaning is completed. The protective material 9 is removed from the mold 10.

[0025] After cleaning, the release agent layer 12 remains on the molding surface 13 of the mold 10. That is, the surface of the molding surface 13 is covered with the release agent layer 12, so that releasability is ensured. The cleaned mold 10 can be used again for vulcanizing green tires, utilizing the existing release agent layer 12. In this way, the adhering dirt X is removed while ensuring the releasability of the molding surface 13, so that the time and cost required for cleaning can be reduced.

[0026] As described above, it is preferable to set the initial thickness of the release agent layer 12 to be larger than the general thickness, or to be 50 μm or more, more preferably 80 μm or more, since this widens the range of suitable cleaning time. This also makes it possible to increase the number of times that the existing release agent layer 12 can be used. As described above, even if the release agent layer 12 is made thicker, the amount of dirt X that adheres to it does not increase.

[0027] The thickness to be removed when removing the release agent layer 12 is determined, for example, before cleaning is started. Specifically, the relationship between the use time of the mold 10 and the amount of dirt X deposited on the release agent layer 12 is grasped in advance. Then, at the time of cleaning the mold 10, the amount of dirt X deposited (deposition thickness) is predicted, and the thickness from the surface of the dirt X to a predetermined depth position exceeding the deposition thickness is determined as the thickness to be removed, and the surface layer 12a is removed. The release agent layer 12 can also be subjected to XRF analysis (X-ray fluorescence analysis) to predict the amount of dirt X deposited (volume thickness) based on the detection rate of the components of the dirt X. Then, for example, while detecting the removal thickness by the distance sensor 6, cleaning is performed until the determined removal thickness is reached, and the surface layer 12a is removed.

[0028] The thickness to be removed when removing the release agent layer 12 can also be determined based on the state of remaining dirt X on the release agent layer 12 ascertained while removing the surface layer 12a. Whether dirt X remains on the surface of the release agent layer 12 can be determined based on various indicators. Examples of such indicators include the color, unevenness (surface roughness), and difference in adhesive strength of the release agent layer 12, and the results of XRF analysis (X-ray fluorescence analysis) of the release agent layer 12.

[0029] Therefore, a target value for the index to be used when the dirt X is substantially not present is set. Then, cleaning is performed while detecting at least one of the indexes, and cleaning is continued until the detected index reaches the target value, thereby removing the surface layer 12a.

[0030] Of the molding surface 13, the tire groove forming portion 14 may have a fine and complex shape. In such a case, it is difficult to remove the surface layer 12a of the release agent layer 12. Therefore, the tire groove forming portion 14 may be excluded from the cleaning target area. That is, cleaning may be performed by setting a simple shape of the molding surface 13, such as a flat surface or a gently curved surface, as the cleaning target area. [Explanation of symbols]

[0031] 1 Cleaning device 2 Processing Heads 2a Nozzle 3 Arm 4. Bass 5 Booth 6 Distance Sensor 7 Processing media supply source 8. Control Unit 9. Protective Materials 10 Vulcanization mold 11 Base surface 12 Release agent layer 12a Surface layer 12b New Surface 13 Molding surface 14 Tire groove forming section M Processing medium X Dirt

Claims

1. 1. A cleaning method for removing dirt that has adhered to the surface of a release agent layer of a vulcanization mold, the surface of which is covered with a release agent layer, during vulcanization of unvulcanized rubber, comprising: the dirt is a component of a rubber composition forming the unvulcanized rubber, A method for cleaning a vulcanization mold, comprising the steps of: scraping the release agent layer to remove the dirt together with a surface layer of the release agent layer without scraping the base surface, thereby leaving the release agent layer to expose a new surface of the release agent layer.

2. 2. The method for cleaning a vulcanization mold according to claim 1, wherein the thickness of the release agent layer to be scraped off is determined before starting cleaning.

3. 2. The method for cleaning a vulcanization mold according to claim 1, wherein a thickness to be scraped off when scraping off the release agent layer is determined based on a remaining state of the dirt grasped while removing the surface layer.

4. The method for cleaning a vulcanization mold according to any one of claims 1 to 3, wherein the release agent layer is initially formed to a thickness of 50 µm or more.

5. The method for cleaning a vulcanization mold according to any one of claims 1 to 4, wherein the vulcanization mold is a tire vulcanization mold, and a tire groove formation portion of the molding surface is excluded from a region to be cleaned.

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