exhaust valve

Abstract

An vent valve for a mold part of a vulcanizing mold for a vehicle tire, the mold part including an inner side of the mold part, the vent valve having a cylindrical housing (1) capable of being pressed into a hole in the mold part, being elongated in the longitudinal direction of the hole and including a central axis (a), and the vent valve having a helical compression spring (5), the helical compression spring being supported inside the housing by having one end abutting against the inner end of the valve stem portion (3a) of the valve head (4) in a direction adjacent to the interior of the housing (1) and having the other end abutting against the housing (1). The helical compression spring (5) is designed and installed to be preloaded when the vent valve is in the closed state, such that in the closed state, the helical compression spring has a spring force F defined as follows: , where , and is , and where D is the outer diameter of the housing (1) in the region adjacent to the valve stem portion (3a) of the valve head (4) in a direction adjacent to the interior of the housing (1).

Description

Technical Field

[0001] This invention relates to an vent valve for a mold part of a vulcanizing mold for vehicle tires. The mold part includes an inner side, and the vent valve has a cylindrical housing that can be pressed into a vent hole in the mold part. The cylindrical housing is elongated in the longitudinal direction of the vent hole and includes a central axis.

[0002] The vent valve has a valve plunger located within the housing and movable axially relative to the housing, and a valve stem with a valve head capable of closing the housing inside the mold part. The vent valve also has a helical compression spring surrounding the valve stem, with one end abutting against the inner end of the valve stem portion of the valve head in a direction adjacent to the inner end of the housing, and the other end abutting against the housing and supported within the housing. The invention also relates to a vulcanizing mold for vehicle tires, the vulcanizing mold having at least one mold part with a vent hole. Background Technology

[0003] To ensure venting of the tire vulcanization mold during green tire molding, multiple vent holes are provided in the mold parts (e.g., in the mold section forming the tread area of ​​the tire). Vent valves are typically installed in the vent holes. Known vent valves include valve inserts with valve heads that close the vent holes inside the mold parts when the green tire has been molded, and are designed to substantially prevent the formation of rubber flash during tire vulcanization and to prevent the rubber compound from entering the interior of the vent valve. Before and at the beginning of green tire molding, the valve closure is open and protrudes slightly from the inside of the mold parts, thereby ensuring the necessary venting during green tire molding.

[0004] The type of exhaust valve mentioned in the introduction is known, for example, from WO 2019 / 219304 A1. In an embodiment of an exhaust valve known from DE 10 2016209 912 A1, the valve head has a truncated conical design and, when the exhaust valve is in the closed position, contacts a valve seat surface located on the inside of a housing that has been pressed into the exhaust port, the valve seat surface being adapted to the truncated conical shape of the valve head.

[0005] A common occurrence is that during the molding of green tires in a vulcanizing mold, a small amount of the rubber composition (especially in the case of rubber compositions with a particularly flowable stage) enters the vent valve and remains as a sticky residue on the underside of the valve head and the valve body, causing the vent valve to no longer open properly after the tire is demolded. This malfunctioning, stuck vent valve creates defects in the vulcanized tire, necessitating interruption of the vulcanization process in the problematic mold, disassembly of the mold components, and manual replacement of the valve plunger. Summary of the Invention

[0006] The purpose of this invention is to ensure the permanent function of the exhaust valve using particularly simple measures, especially in cases where the rubber composition causes the exhaust valve to stick.

[0007] According to the present invention, the stated object is achieved in such a way that the helical compression spring is designed and installed under preload when the exhaust valve is closed, such that in the closed state, the helical compression spring has a spring force F defined as follows:

[0008]

[0009] in,

[0010] ,and

[0011] ,

[0012] And D is the outer diameter of the housing (1) in the region adjacent to the valve stem portion (3a) of the valve head (4) in the direction inside the housing (1).

[0013] According to the invention, the exhaust valve contains helical compression springs whose spring force ensures that even if the valve head or plunger and the inner side of the housing are contaminated, the helical compression springs can overcome the resulting adhesive forces and always ensure that the valve can be opened after the fully vulcanized tire is removed. Here, the spring force is selected based on the fluidity of certain components of the potentially entering rubber compound or rubber composition, the previously determined degree of contamination (preferably in the stated area), and the outer diameter of the housing. Therefore, the invention also takes into account the fact that a stronger spring is advantageous in exhaust valves with a relatively large outer diameter. Thus, the invention avoids production stoppages by preventing situations where the exhaust valve becomes inoperable and the tire mold needs to be disassembled for cleaning purposes beyond the expected intervals.

[0014] In a preferred embodiment, in the closed state, the helical compression spring has a spring force F, wherein This range of spring forces has proven to be particularly suitable and advantageous for exhaust valves with common housing outer diameters, ensuring that, in most cases, even with relatively heavy rubber material contamination, the exhaust valve can reliably open after tire demolding.

[0015] The valve stem portion adjacent to the valve head is specifically designed to have an outer diameter that is 85% to 90% of the inner diameter of the housing at that point. This design ensures a narrow gap between the valve stem portion and the housing and reduces the possibility of rubber material entering the area of ​​the helical compression spring.

[0016] Another advantage in this regard is that the valve stem portion adjacent to the valve head has a height of 1.50 mm to 2.50 mm measured parallel to the central axis.

[0017] In a further advantageous embodiment, the inner end of the valve stem portion has an externally surrounding annular support surface, oriented perpendicular to the central axis and having a width specifically of 0.20 mm to 0.60 mm, against which one end of the helical compression spring is supported. The valve stem portion is adjacent to another valve stem portion with a smaller diameter, thereby ensuring the required mobility of the helical compression spring.

[0018] The present invention also relates to a vulcanizing mold for a vehicle tire, the vulcanizing mold having at least one front part having vent holes, wherein an vent valve as described in one or more of claims 1 to 6 is inserted into these vent holes. Attached Figure Description

[0019] Further features, advantages, and details of the invention will be described in more detail with reference to the schematic drawings illustrating exemplary embodiments of the exhaust valve. In the drawings:

[0020] Figure 1 A significantly enlarged partial cross-sectional view of the exhaust valve in the closed state is shown.

[0021] Figure 2 A view of the valve plunger of the exhaust valve is shown. Detailed Implementation

[0022] Figure 1 An exemplary embodiment of an exhaust valve is shown, which is inserted into a hole in a mold part (e.g., a mold section) of a vulcanizing mold for a vehicle tire, particularly for a pneumatic vehicle tire. In the following description of an embodiment of the exhaust valve, the design and arrangement of the components of the exhaust valve will be described with respect to the mounting position of the components of the exhaust valve in the mold part, which has an inner mold part facing the mold cavity and an outer mold part opposite to the inner mold part.

[0023] The main components of the vent valve are an elongated housing 1 and an equally elongated valve plunger 2. The housing is a generally cylindrical component with a central axis a, and the vent valve is inserted into the bore of the mold part in an interference fit manner by means of this housing, with the valve plunger inserted into the housing 1 along the central axis a. The valve plunger 2 has a valve head 4 facing the inside of the mold and a valve stem 3, which is composed of multiple parts and surrounded by a helical compression spring 5. The valve head 4 has, for example, a flat truncated conical shape, with an outer side facing the inside of the mold and an inner side adjacent to the valve stem 3. When the vent valve is in the open position, the outer side of the valve head 4 protrudes beyond the inside of the mold part under the pressure of the helical compression spring 5, creating a gap between the valve head 4 and the housing 1. Air enters the vent valve through this gap and exits through the orifice portion of the bore in the mold part. The green tire, already molded into the vulcanizing mold, presses the valve head 4 against the surrounding valve seat surface on the housing 1, and thus presses the valve head into its closed position.

[0024] like Figure 1 and Figure 2 As shown, the valve head 4 is centrally adjacent to the valve stem portion 3a in the direction inside the housing 1. This valve stem portion is specifically cylindrical, and its outer diameter d1 is 85% to 90% of the inner diameter of the housing 1 at that point, such that a gap of preferably 0.07 mm to 0.17 mm is left between the outer side of the valve stem portion 3a and the inner side of the housing 1. In the region of the valve stem portion 3a, the housing 1 has an outer diameter D, which... Figure 1 The instructions are in accordance with the central government.

[0025] The height h of the valve stem portion 3a, measured parallel to the central axis a, is specifically 1.50 mm to 2.50 mm, and particularly approximately 2.00 mm. The valve stem portion 3a is adjacent to other stem portions, which are not shown except for the end portion 3b, and each has a diameter smaller than that of the valve stem portion 3a. This embodiment results in an externally surrounding annular support surface 6 on the inner end of the valve stem portion 3a, the width of which is specifically 0.20 mm to 0.60 mm, and one end of a helical compression spring 5 is supported against this support surface.

[0026] The helical compression spring 5 is supported inside the housing by its second end abutting against, in particular, a surrounding protrusion 7, which is formed on the inner end of the housing 1 and provides a centrally located free opening. The aforementioned end portion 3b of the valve stem 3 is divided into two parts by a slot 8, and each of these two parts has a protrusion 9 on its outer side, such that when the valve stem 3 is inserted into the housing 1, the protrusion 9 latches into place below the surrounding protrusion 7 on the inner end of the housing 1.

[0027] In a preferred embodiment, the helical compression spring 5 has six to eight turns and is made of metal wire with a diameter of, for example, 0.20 mm to 0.25 mm. The inner and outer diameters of the helical compression spring 5 are such that the spring is optimally supported inside the housing while exhibiting good compressibility and mobility against the support surface 6 of the valve stem portion 3a and against the protrusion 7 of the housing 1. The helical compression spring 5 is designed and installed in the exhaust valve such that when the exhaust valve is closed, the helical compression spring applies a spring force F as determined below:

[0028]

[0029] in,

[0030] ,and

[0031] In particular, .

[0032] Therefore, when the exhaust valve is in the closed position, the spring force of the preloaded helical compression spring 5 ensures that the exhaust valve reliably returns to its open position even when there are sticky residues of rubber material on the housing 1 and / or the conical lower side of the valve head 4 after the tire has been demolded.

[0033] List of reference numerals

[0034] 1.....................Shell

[0035] 2.....................Valve plunger

[0036] 3.....................Valve stem

[0037] 3a, 3b........... Valve stem section

[0038] 4.....................Valve head

[0039] 5.....................Helical compression spring

[0040] 6.....................Supporting Surface

[0041] 7.....................Prominent part

[0042] 8..................... Slot

[0043] 9.....................Prominent part

[0044] a.....................Central axis

[0045] h.....................height

[0046] d1....................Outer diameter of valve stem section 3a

[0047] D.....................Outer diameter of shell 1.

Claims

1. An vent valve for a mold part of a vulcanizing mold for vehicle tires, the mold part including an inner side of the mold part, The exhaust valve has a cylindrical housing (1) that can be pressed into a hole in the mold part, is elongated in the longitudinal direction of the hole, and includes a central axis (a). The exhaust valve has a valve plunger (2) located in the housing (1) and movable in the axial direction relative to the housing, and a valve stem (3) having a valve head (4) capable of closing the housing (1) inside the mold part. The exhaust valve also has a helical compression spring (5) surrounding the valve stem (3), with one end abutting against the inner end of the valve stem portion (3a) of the valve head (4) in a direction adjacent to the inner end of the housing, and the other end abutting against the housing (1) and supported inside the housing. Its features are, The helical compression spring (5) is designed and installed to be preloaded when the exhaust valve is in the closed state, such that in the closed state, the helical compression spring has the following defined spring force F: in, and ， And D is the outer diameter of the housing (1) in the region adjacent to the valve stem portion (3a) of the valve head (4) in the direction inside the housing (1).

2. The exhaust valve as described in claim 1, characterized in that, In this closed state, the helical compression spring (5) has a spring force F, wherein 。 3. The exhaust valve as described in claim 1 or 2, characterized in that, The valve stem portion (3a) adjacent to the valve head (4) has an outer diameter (d1) that is 85% to 90% of the inner diameter of the housing (1) at that point.

4. The exhaust valve as described in any one of claims 1 to 3, characterized in that, The valve stem portion (3a) adjacent to the valve head (4) has a height (h) measured parallel to the central axis (a) of 1.50 mm to 2.50 mm.

5. The exhaust valve as described in any one of claims 1 to 4, characterized in that, The valve stem portion (3a) has an outer annular support surface (6) on its inner end, the width of which is specifically 0.20 mm to 0.60 mm, and one end of the helical compression spring (5) is supported against this support surface.

6. A vulcanizing mold for a vehicle tire, the vulcanizing mold having at least one mold part having vent holes, into which vent valves designed as described in one or more of claims 1 to 5 are inserted.

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