Ventilation device, vulcanization mold and vehicle pneumatic tire

Abstract

A ventilation device (3) for insertion into a hole (2) from the inside of a molded part (1) of a vulcanizing mould for vulcanizing a green tyre, the ventilation device (3) having a closed position and an open position and having the following components: a housing (6); a valve insert (7); a valve disk (4) belonging to the valve insert (7), which, in the closed position of the ventilation device (3), rests with a circumferential edge region (4a) on an annular circumferential mating surface on the outer end of the housing (6); a valve rod (8) belonging to the valve insert (7) and having a cylindrical outer rod section (8a); and-a helical compression spring (10). The thickness (s1) of the outer edge region (4a) of the valve disk (4) is between 0.10 mm and 0.40 mm, in particular between 0.20 mm and 0.25 mm. The ventilation device (3) is pressed into the bore (2) in such a way that a mating surface (13) surrounding the outer end of the housing (6) is offset inwards by 0.05 mm to 0.35 mm, in particular 0.10 mm to 0.15 mm, relative to the molded part inner side (1a).

Description

Technical Field

[0001] The present invention relates to a ventilation device for inserting into a hole of a molding part of a vulcanization mold for vulcanizing a green tire from the inside of the molding part,

[0002] The ventilation device has a closed position and an open position and comprises the following components:

[0003] a largely cylindrical, sleeve-shaped housing that can be pressed into the bore and has a largely constant inner diameter and a central axis;

[0004] a valve insert which is inserted into the housing and is movable axially relative to the housing;

[0005] a valve disk belonging to the valve insert, which is circular in plan view and, in the closed position of the ventilation device, rests flatly with a circumferential edge region of constant thickness on an annularly surrounding seating surface on the outer end of the housing and oriented at right angles to the central axis;

[0006] a valve stem belonging to the valve insert and adjoining the valve disk, the valve stem comprising a cylindrical outer stem section, an inner stem section and a transition section between the stem sections;

[0007] A helical compression spring which surrounds the inner stem section and the transition section of the valve stem and is supported with one end on the housing and acts with its other end on the outer stem section of the valve stem.

[0008] The invention further relates to a vulcanization mold having at least one molded part with ventilation holes and a pneumatic vehicle tire vulcanized in the vulcanization mold. Background Art

[0009] To ensure ventilation of the tire vulcanization mold during the green tire molding process, a plurality of ventilation holes are provided in the molding part, particularly in the molding segment in the tread area, with ventilation devices incorporated into each of these ventilation holes. This type of ventilation device comprises a valve insert with a valve closure, such as a valve disk. During the green tire molding process, the venting insert or its valve closure opens and protrudes inside the molding part (e.g., in the molding segment), thereby ensuring the required ventilation during the green tire molding process.

[0010] A ventilation device of the type described at the beginning is known, for example, from WO 2020 / 211995 A1. The valve closure is segmented in a stepped manner on the outside and is supported on the correspondingly segmented inner wall section of the housing in the closed position of the ventilation device. Here, the size and configuration of the steps are such that, in the closed position of the ventilation device, an annular gap is left between the corresponding step surfaces at the valve closure and those step surfaces at the inner wall section of the housing, the width of the gap being 0.01mm to 0.50mm. All gaps are connected to each other, thereby forming a unique continuous stepped gap extending from the contact surface to the inside of the ventilation device, which changes direction according to the number of steps. The above-mentioned gap acts as a labyrinthine gap and therefore acts as a barrier in a known manner to prevent liquid media or low-viscosity media (especially particularly fluid rubber mixtures) from passing through or penetrating into the interior of the ventilation device. Even when the ventilation device is closed, the valve closure protrudes slightly from the inside of the molded part, the protrusion being in the order of 0.05 mm to 0.20 mm and contributing to good closing of the ventilation device and to the formation of counterpressure in the gap.

[0011] WO 2017 / 211517 A1 discloses another ventilation device for a vulcanization mold for pneumatic vehicle tires. This device comprises a valve stem with a truncated-conical, outwardly widened valve disc. When the device is closed, the valve disc abuts against a diametrically oppositely formed widened portion of an inner wall section outside the housing. The valve stem and the valve disc have a cylindrical retaining section adjacent to the valve stem. A helical compression spring, which compresses the valve stem and thereby presses the valve disc into the open position, can be fitted with at least two of its coils onto the retaining section. This measure allows for precise positioning of the helical compression spring and a tight fit with the valve stem.

[0012] During the tire shaping process, the problem of modern, particularly fluid rubber compounds used in high-performance tires unexpectedly infiltrating into the ventilator due to additional heating has never been satisfactorily resolved. These special rubber compounds leave visible burrs of various shapes and sizes around the ventilator. In addition, with known ventilators, after a certain number of heating cycles, it is almost inevitable that the rubber compound that has infiltrated into the ventilator due to its fluidity will fill the ventilator with rubber material and block the ventilator, especially the helical compression spring. Therefore, it is no longer possible to ensure that the vulcanization mold is fully ventilated, and pinch points will appear on the vulcanized tire, which will damage the quality of the vulcanized tire, so that these pinch points must even be removed. The relevant vulcanization mold must be removed from the tire hot press, the ventilator removed and replaced with a new one. These measures cause production to stop, thereby increasing costs, and the latter also requires the installation of a new ventilator. Summary of the Invention

[0013] The object of the present invention is to improve a ventilation device of the type mentioned in the introduction in such a way that the formation of burrs is reliably avoided and that perfect ventilation is ensured over significantly more heating cycles than with known ventilation devices, in particular by making the penetration of the rubber mixture more difficult and ensuring trouble-free operation of the helical compression spring over a large number of heating cycles.

[0014] According to the invention, the proposed object is achieved in that the thickness of the outer edge area of ​​the valve disc on the mating surface in the closed position of the ventilation device is 0.10 mm to 0.40 mm, in particular 0.20 mm to 0.25 mm, wherein the ventilation device is pressed into the hole in such a way that the mating surface surrounding the outer end of the housing is offset inwardly by a distance of 0.05 mm to 0.35 mm, in particular 0.10 mm to 0.15 mm, relative to the inner side of the molded part, and wherein the outer diameter of the radially outer rod section of the valve stem is 80% to 97% of the inner diameter of the housing.

[0015] According to the invention, these measures, combined with one another, ensure trouble-free operation of the ventilation device over significantly more heating cycles than with known ventilation devices, even with particularly fluid rubber compounds in the warm, uncured state. By appropriately adjusting the distance between the mating surface on the housing and the inside of the mold, and the thickness of the valve disc's edge therein in the closed position, the travel distances during opening and closing are very small, and when the ventilation device is closed, the valve disc protrudes only slightly beyond the inside of the molded part. This, on the one hand, optimally assists closing the ventilation device during the green tire molding process, while on the other hand, the narrow gap present when the ventilation device is open leaves virtually no room for rubber material to penetrate. Furthermore, the equally narrow gap between the radially outer stem section of the valve stem and the inner wall of the housing prevents any potentially intrusive rubber material from penetrating into sensitive areas of the helical compression spring while still being fluid.

[0016] Particularly preferred is an embodiment in which the outer diameter of the radially outer shaft section of the valve shaft is 85% to 90% of the inner diameter of the housing.

[0017] In another preferred embodiment, the radially outer shaft section of the valve stem has an extension length such that the location at which the helical compression spring acts on the section is located at a distance from the outer end of the ventilation device that is 30% to 60% of the total length of the ventilation device. This measure also helps prevent any infiltrating rubber compound or rubber material from penetrating into the region of the helical compression spring.

[0018] It is also advantageous if the surrounding mating surface at the outer end of the housing is the free outer edge of the housing. Therefore, when the ventilation device is pressed into the hole, only a hole wall section extending to the inside of the molded part is present outside the mating surface. This hole wall section preferably has a height of 0.10 mm to 0.15 mm, determined along the direction of extension of the hole. This allows the ventilation device to be pressed only a short distance into the hole without damaging the housing.

[0019] Optimal seating of the valve disc on the mating surface of the housing is supported in particular by the fact that the outer edge region of the valve disc has a width of 0.20 mm to 0.30 mm and overlaps with the mating surface at the outer edge of the housing in such a way that, when the ventilation device is closed, a gap with a width of 0.04 mm to 0.06 mm remains between the edge of the edge region of the valve disc and the hole wall section.

[0020] The optimal fit of the valve disc on the fitting surface of the housing with good mobility is preferably also ensured in that the fitting surface, which surrounds the end of the housing located on the inner side of the molded part, surrounds an opening of the housing that widens outwards in a funnel-shaped manner on the outside and is formed by the continuous reduction of the wall thickness of the housing, so that the width of the fitting surface is 0.20 mm to 0.35 mm.

[0021] The mobility and stability of the valve disk are further supported in that the valve disk has a disk base, which extends to the adjacent outer shank section in the form of a truncated cone section with a reduced diameter, wherein the truncated cone section parallel to the central axis has a thickness of 0.25 mm to 0.40 mm and the smallest diameter of the truncated cone section is located at the connection with the outer shank section and is 0.20 mm to 0.40 mm larger than the diameter of the outer shank section.

[0022] In order to achieve long-term operation of the helical compression spring, it is advantageous according to another design scheme that an annular supporting surface is formed on the outer shaft section of the valve stem at the transition section, on which the helical compression spring is supported and thus presses the valve stem and thus the valve disk into the open position.

[0023] The vulcanization mold according to the invention has at least one molded part with ventilation holes, into which ventilation devices according to one or more of claims 1 to 8 are inserted. It is particularly advantageous if the molded parts are molded segments that form segment rings for molding the tread of a pneumatic vehicle tire. Using such a vulcanization mold, tires whose treads are made of rubber compounds that are extremely soft and therefore particularly fluid in the warm, unvulcanized state can be vulcanized during numerous heating cycles without producing noticeable burrs on the tread.

[0024] The vehicle pneumatic tire according to the present invention is vulcanized in the vulcanization mold according to claim 9 or 10 . BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further features, advantages and details of the present invention will now be described in detail with reference to the accompanying drawings which illustrate exemplary embodiments. In the drawings:

[0026] Figure 1 An enlarged view (partially cut away) showing the ventilation device in the closed state,

[0027] Figure 2 An enlarged sectional illustration (longitudinal section) of the housing of the ventilation device inserted into the molded part, and

[0028] Figure 3 Shown is an enlarged view of the valve stem.

[0029] List of Reference Numerals

[0030] 1...................Molding parts

[0031] 2...................Ventilation holes

[0032] 1a..................Inside of molded part

[0033] 3...................Ventilation

[0034] 4...................Valve disc

[0035] 4a..................Marginal area

[0036] 5...................Tread

[0037] 6...................Housing

[0038] 6a..................Outer shell section

[0039] 6b....................Inner casing section

[0040] 6a1, 6b1.............End section

[0041] 7...................Valve insert

[0042] 8...................Valve stem

[0043] 8a..................Outer rod section

[0044] 8a1.................Support surface

[0045] 8b..................Transition section

[0046] 8c..................Inner rod section

[0047] 8c1.................End section

[0048] 9...................Bottom of the plate

[0049] 10..................Coil compression spring

[0050] 11..................Open

[0051] 11a.................Inclined surface

[0052] 12..................Protrusion

[0053] 13..................Annularly encircled mating surface 14...................Slot

[0054] 15..................Protrusion

[0055] a...................Central axis

[0056] α.................Angle (inclined surface 11a)

[0057] d1..................Inner diameter of housing 6

[0058] d2..................Outer diameter of outer shell segment 6a

[0059] d3..................Outer diameter of inner housing section 6b

[0060] d4..................Inner diameter of mating surface 13

[0061] d5..................Diameter of the opening at protrusion 12

[0062] d6..................Diameter of valve disc 4

[0063] d7..................The maximum diameter of the truncated cone section of the base 9 of the dish

[0064] d8..................Outer diameter of the shank section 8a

[0065] s1..................Thickness of valve disc 4

[0066] s2..................Thickness of the truncated cone section at the base of the disk

[0067] b...................Width of mating surface 13

[0068] L...................Total length of ventilation device 3

[0069] L8..................Total length of valve stem 8

[0070] c...................distance DETAILED DESCRIPTION

[0071] Figure 2 A cross-sectional view of a housing 6 of a ventilation device 3 is shown, which is inserted into a hole 2 of a molding part 1 (e.g., a molding segment) in a vulcanization mold for a pneumatic vehicle tire. The molding part 1 has an inner side 1a facing the mold cavity and an outer side (not shown). Typically, a plurality of molding segments form a molding segment ring to mold a treaded surface of a green tire inserted into the vulcanization mold.

[0072] In the following description of an embodiment of the ventilation device 3, the design and arrangement of its components will be considered with reference to the installation position of its components in the molded part 1 (such as the molded segment of the segment ring of the molded tread), where the terms "external", "outside", "outside" and the like refer to positions located at or near the inner side 1a of the molded part, and the terms "inside", "inside", "inside" and the like refer to positions further inside the molded part 1 or the ventilation device 3.

[0073] Especially Figure 1As shown, the essential components of each ventilation device 3 are an elongated housing 6 and a similarly elongated valve insert 7 inserted into the housing 6. The housing 6 is a largely cylindrical component with a central axis a. The valve insert 7 comprises a valve stem 8, a valve disc 4 with a disc base 9 (located outside the valve stem), and a helical compression spring 10. The central axis a is also the central longitudinal axis of the valve insert 7, which is designed to be largely rotationally symmetrical. In the open position of the ventilation device 3, the top side of the valve disc 4 projects at least beyond the inner side 1a of the molded part, allowing air to penetrate into the ventilation device 3 and escape therefrom. The green tire molded in the vulcanization mold presses the valve disc 4 into its closed position.

[0074] like Figure 2 The housing 6 shown, which is sleeve-shaped and designed rotationally symmetrically with respect to the axis a, comprises an outer housing section 6a with a specially designed end section 6a1 and an inner housing section 6b with a specially designed end section 6b1. Between the two end sections 6a1, 6b1, the housing sections 6a and 6b have an identical and constant inner diameter d1 of 1.60 mm to 2.20 mm. The outer housing section 6a has a constant outer diameter d2, and the inner housing section 6b has a constant outer diameter d3, with outer diameter d2 being 0.10 mm to 0.40 mm, preferably 0.15 mm to 0.30 mm, greater than outer diameter d3. Consequently, the wall thickness of the housing 6 in the outer housing section 6a is greater than that in the inner housing section 6b.

[0075] In the end section 6a1 (which, viewed parallel to the axis a, extends over a distance of 0.40 to 0.50 mm), a funnel-shaped, outwardly widening opening 11 is formed due to the continuously decreasing wall thickness and increasing inner diameter of the housing 6. This opening 11 is surrounded by an inclined surface 11a extending at a constant angle α of 20 to 24° relative to the central axis a. Opening 11 is surrounded on the outside by an annular, planar mating surface 13 oriented at right angles to the axis a, having a constant width b of 0.20 to 0.35 mm and an inner diameter d4 of 1.90 to 2.70 mm. The mating surface 13 forms the free outer edge of the housing 6.

[0076] In the end section 6b1 of the inner housing section 6b, a protrusion 12 surrounding the inner wall is formed on the inner wall. The protrusion leaves a circular opening with a diameter d5 that is 0.50 mm to 0.80 mm smaller than the inner diameter d1 of the housing 6.

[0077] The ventilation device 3 is inserted into the ventilation opening 2 of the molded segment 1 by means of a press fit, such that an annularly circumferential seating surface 13 on the outside of the housing 6 lies within the molded part interior 1a and is offset inwardly relative to the molded part interior by a distance c of 0.05 mm to 0.35 mm, in particular 0.10 mm to 0.15 mm. In the closed position of the ventilation device 3, the valve disk 4 rests on the annularly circumferential seating surface 13.

[0078] Especially Figure 3 As shown, the valve disk 4, which appears circular in top view, has, on its outer side, a diameter d6 that is 0.30 mm to 0.60 mm larger than the inner diameter d4 of the seating surface 13; and an edge region 4a surrounding the disk base 9, which has a constant thickness s1 of 0.10 mm to 0.40 mm, particularly 0.20 mm to 0.25 mm, and a constant width of 0.20 mm to 0.30 mm. A narrow, circumferential gap of approximately 0.04 mm to 0.06 mm remains relative to the wall of the ventilation opening 3. This ensures that, in the closed position of the ventilation device 3, the valve disk 4 rests flatly on the seating surface 13 at its edge. In this position, the valve disk 4, due to its thickness s1, protrudes approximately 0.10 mm beyond the inner side 1a of the molded part. The disk base 9 has a truncated cone-shaped section with a diameter that decreases toward the interior of the housing 6, wherein its maximum diameter d7 is 0.40 mm to 0.60 mm smaller than the diameter d6 of the outer side of the valve disk 4, and a thickness s2 of 0.25 mm to 0.40 mm. The inclination of the outer surface of the disk base 9 relative to the central axis a is selected such that the disk base 9 does not contact the inner wall of the housing 6 in the closed position of the ventilation device 3.

[0079] Adjacent to the disk base 9 is the valve stem 8 with a cylindrical outer stem section 8a, followed by a transition section 8b, and then by an inner stem section 8c with an end section 8c1. The outer diameter d8 of the outer stem section 8a is 80% to 97%, particularly 85% to 90%, of the inner diameter d1 of the housing 6. The shortest length of the outer stem section 8a is 2.50 mm and preferably exceeds 30% to 50%, particularly 38% to 43%, of the total length L8 of the valve stem 8. The diameter of the valve stem 8 is greatest in the outer stem section 8a and smallest in the inner stem section 8c. The diameter of the transition section 8b is smaller than the diameter of the outer rod section 8a and larger than the diameter of the inner rod section 8c, in such a way that an annular supporting surface 8a1 is still left on the outer rod section 8a relative to the transition section 8b, and one end of the helical compression spring 10 (which is located around the inner rod section 8c and around the transition section 8b) is supported on this supporting surface. The outer rod section 8a preferably has such an extension length that the position where the helical compression spring 10 acts on this section is located at a position determined from the outer end of the ventilation device 3 and is the total length L ( Figure 1 ) at a distance of 30% to 60% of the ).

[0080] A slot 14 is formed in the inner stem section 8c and extends along the central axis a on the end section 8c1. The end section 8c1, thus divided into two parts by the slot 14, has a protrusion 15 on the outside. When the valve stem 8 is inserted into the housing 6, the protrusion 15 snaps under the surrounding protrusion 12 at the inner end of the housing 6. The helical compression spring 10 located on the inner stem section 8c is supported by its second end on the surrounding protrusion 12 inside the housing.

Claims

1. A ventilation device (3) for insertion into a hole (2) from the inside of a molding (1) of a vulcanization mold for vulcanizing a green tire, The ventilation device (3) has a closed position and an open position and comprises the following components: a largely cylindrical, sleeve-shaped housing (6) which can be pressed into the bore (2) and has a largely constant inner diameter (d1) and a central axis (a); - a valve insert (7) which is inserted into the housing (6) and is movable axially relative to the housing; a valve disk (4) belonging to the valve insert (7) and having a circular shape in top view, which, in the closed position of the ventilation device (3), rests flatly with a circumferential edge region (4a) of constant thickness (s1) on a mating surface on the outer end of the housing (6) which is circumferentially surrounding and oriented at right angles to the central axis and remains positioned within the mating surface (13); a valve stem (8) belonging to the valve insert (7) and adjoining the valve disk (4), the valve stem comprising a cylindrical outer stem section (8a), an inner stem section (8c) and a transition section (8b) between the stem sections (8a, 8c); a helical compression spring (10) which surrounds the inner stem section (8c) and the transition section of the valve stem (8) and is supported with one end on the housing (6) and acts with the other end on the outer stem section (8a) of the valve stem (8), It is characterized by: The thickness (s1) of the outer edge region (4a) of the valve disc (4) placed on the fitting surface (13) in the closed position of the ventilation device (3) is 0.10 mm to 0.40 mm, in particular 0.20 mm to 0.25 mm, wherein the ventilation device (3) is pressed into the hole (2) in such a way that the fitting surface (13) surrounding the outer end of the housing (6) is offset inwardly by a distance (c) of 0.05 mm to 0.35 mm, in particular 0.10 mm to 0.15 mm, relative to the inner side (1a) of the molded part, and wherein the outer diameter (d8) of the radial outer rod section (8a) of the valve stem (8) is 80% to 97% of the inner diameter (d1) of the housing (6).

2. The ventilation device (3) according to claim 1, characterized in that The outer diameter (d8) of the radially outer stem section (8a) of the valve stem (8) is 85% to 90% of the inner diameter (d1) of the housing (6).

3. The ventilation device (3) according to claim 1 or 2, characterized in that The radially outer rod section (8a) of the valve rod (8) has such an extension length that the position at which the helical compression spring (10) acts on the section (8a) is located at a distance from the outer end of the ventilation device (3) that is 30% to 60% of the total length (L) of the ventilation device (3).

4. Ventilation device (3) according to one or more of claims 1 to 3, characterized in that The fitting surface (13) surrounding the outer end of the housing (6) is the free outer edge of the housing (6), so that when the ventilation device (3) is pressed into the hole (2), there is a hole wall section outside the fitting surface (13) that extends to the inner side of the molded part.

5. Ventilation device (3) according to one or more of claims 1 to 4, characterized in that The outer edge region (4a) of the valve disc (4) has a width of 0.20 mm to 0.30 mm and overlaps with the mating surface (13) at the outer edge of the housing (6) in such a way that when the ventilation device (3) is closed, a gap with a width of 0.04 mm to 0.06 mm remains between the edge of the edge region (4a) of the valve disc (4) and the hole wall section.

6. Ventilation device (3) according to one or more of claims 1 to 5, characterized in that The mating surface (13) surrounding the end of the shell (6) located on the inner side of the molded part surrounds the funnel-shaped outwardly widening opening (11) of the shell (6) on the outside, and the opening is formed by the continuous reduction of the wall thickness of the shell (6), so that the width (b) of the mating surface (13) is 0.20mm to 0.35mm.

7. Ventilation device (3) according to one or more of claims 1 to 6, characterized in that The valve disc (4) has a disc base (9), which extends in a truncated cone section with a reduced diameter up to the adjacent outer rod section (8a), wherein the truncated cone section parallel to the central axis has a thickness (s2) of 0.25 mm to 0.40 mm, and its smallest diameter is located at the connection with the outer rod section (8a) and is 0.20 mm to 0.40 mm larger than the diameter (d8) of the outer rod section (8a).

8. Ventilation device (3) according to one or more of claims 1 to 7, characterized in that On the outer rod section (8a) of the valve rod (8), an annular supporting surface (8a1) is left at the transition section (8b), and the helical compression spring (10) is supported on the supporting surface.

9. A vulcanization mold for a pneumatic vehicle tire, the vulcanization mold comprising at least one molded part with ventilation holes, into which ventilation holes a ventilation device according to one or more of claims 1 to 8 is inserted. 10 . The vulcanization mold according to claim 9 , wherein the molding piece is a molding segment forming a segment ring for molding a tread of the vehicle pneumatic tire.

11. A pneumatic tire for a vehicle, which is vulcanized in the vulcanization mold according to claim 9 or 10.

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