WO2017211476A1

WO2017211476A1 - Ventilation unit for a vulcanization mold of a vehicle pneumatic tyre

Info

Publication number: WO2017211476A1
Application number: PCT/EP2017/057158
Authority: WO
Inventors: Magnus HASSELLÖF; Jürgen DZICK
Original assignee: Continental Reifen Deutschland Gmbh
Priority date: 2016-06-06
Filing date: 2017-03-27
Publication date: 2017-12-14
Also published as: DE102016209913A1

Abstract

The invention relates to a ventilation unit (3) for a vulcanization mold of a vehicle pneumatic tire having a central longitudinal axis (a), a cylindrical housing (6), which can be pressed into a ventilation bore (2) in the vulcanization mold, and a valve insert (7), which is positioned in the housing (6) and is movable with respect thereto and which has a valve stem (8) having a valve disc (4', 4") and a helical compression spring (9) surrounding the valve stem (8), one end of the compression spring being supported on the housing (6) and the other end being supported internally on the valve disc (4', 4"), said valve disc having externally a surface (4'a, 4''a) which is associated with the vulcanization mold cavity and has a circular contour in plan view, wherein the circle centre point is located on the central longitudinal axis (a). At least one raised area and/or at least one depression is formed on the surface (4'a, 4''a) of the valve disc (4', 4'').

Description

description

Venting unit for a vulcanization mold of a pneumatic vehicle tire

The invention relates to a venting unit for a vulcanization mold of a

Pneumatic vehicle tire with a central central longitudinal axis, one in one

Ventilation bore of the vulcanization mold einpressbaren cylindrical housing and a positioned in the housing and relative to this movable valve insert, which has a valve stem with a valve plate and a surrounding the valve stem helical compression spring, which is supported at one end to the housing and at the other end to the valve plate, which on the outside one of the

Vulkanisationsformkavität associated, in plan view of a circle encircling

Has surface, wherein the circle center is located on the central central longitudinal axis.

It is known and customary that in vulcanization molds for pneumatic vehicle tires, in particular for passenger cars, there are on average approximately 4500 ventilation holes with the same number of ventilation units used in these. The

Venting units contain valve inserts whose valve disc is molded

Tire blanking the vent holes and the emergence of

Rubber exhausts during vulcanization of the tire at least largely prevent. During the molding of the green tire, the valve inserts are opened, the valve plates are on the inner side of the mold, so that the required venting can take place during the molding of the green tire. A venting unit of the aforementioned type is known, for example, from EP 0 774 333 B1. The

Valve plates of the known venting unit have an outer planar surface. Although there are no or hardly any rubber exhausts on the finished vulcanized tire, there are often disturbing "impressions" of the valve disks in the outer surface of the tire, especially on the tread surface. The invention is based on the object to avoid the occurrence of such imprints and to improve the functionality of the valve disc.

The object is achieved according to the invention in that at least one elevation and / or at least one recess is formed on the surface of the valve disk.

By surveys and / or depressions on the valve plate can specifically local

Wells or ridges on the tread of the tire are formed, which are perceived as visually less disturbing than the impressions of valve plates with a flat surface. Elevations on the valve plate also allow a faster

Close the vent hole. By "pulling on the closing", it is possible to prevent rubber from penetrating into the housing. The valve plate closes the opening before the rubber compound is everywhere, but at the same time the required ventilation is completed and there are no shrinkage points. This is for example an advantageous special solution for tread compounds that have a very high flow behavior during molding in the mold, therefore, could penetrate into the housing and enforce the spring. Occurs by means of at least one survey on the valve disk closing before the rubber mixture touches the mold surface everywhere, the

Rubber compound does not flow into the housing.

For an optimal closing of the vent hole, it is advantageous if the height of the survey or elevations highest the stroke of the valve stem or in the

Substantially corresponds to the stroke of the valve stem. In this context, it is also advantageous if the depression or elevation is symmetrically arranged or formed with respect to at least one plane which contains the central central longitudinal axis.

Embodiments of the invention are preferred in which the elevation is a curvature of the entire surface of the valve disk to the outside and the depression is a curvature of the entire surface of the valve disk to the inside. Particularly preferred is also an embodiment of the invention, in which the curvature is designed substantially spherical segment-shaped, wherein the height or depth of the ball portion corresponds to at most 30% of the radius of the underlying ball.

Further features, advantages and details of the invention will now be described with reference to the drawing. Show

1a and 1b are schematic sectional views of a portion of a mold segment of a vulcanization mold,

2 shows a longitudinal section of a variant of an embodiment of a venting unit according to the invention, FIGS. 3a and 4 show sectional views of individual components of the venting unit according to FIG. 2, FIG. 3b shows a variant of FIGS

Fig. 5 and Fig. 6 variants of the embodiment of a valve disk. Fig. La and lb show sectional views of a part of a mold segment 1 a

Vulcanization mold, which, as is customary, is divided by the tread region-forming part radially into a number of mold segments, wherein in particular between seven and thirteen mold segments are provided. The sections through the mold segment 1 also show a number of longitudinal sections through vent holes 2, which are oriented in the radial direction and in the embodiment shown on the

Formsegmentinnenseite la each having a portion 2a with a larger diameter. In each section 2a a venting unit 3 is used. The

Entlüftungseinheiten 3 are all open in the representation shown in Fig. La - without molded-in green tire - spring-loaded valve disk 4 survive slightly beyond the mold segment inside la and protrude into the Vulkanisationsformkaverne. Fig. Lb shows in an analogous representation of Fig. La the moment where towards the end of Forming a green tire be the tread 5 part with the forming

Mold segment inside la has come into contact, so that the raw tread 5 have pressed the valve disk 4 in the closed position shown in Fig. Lb. Fig. 2 shows in the same sectional plane as the figures la and lb in enlarged

Representation of a single venting unit 3, which a housing 6, a valve insert 7 of a valve stem 8 and the already mentioned valve disk 4 and a

Helical compression spring 9, which surrounds the valve stem 8 and is supported with its one end on the housing 6 and with its other end on the underside of the valve disk 4. The venting unit 3 has one in its longitudinal extent - this corresponds in

Mold segments forming the tread of the radial direction in the tire - extending central longitudinal axis a, with respect to which most of the components of the venting unit 3 are rotationally symmetrical. The central longitudinal axis a of the ventilation unit 3 is therefore at the same time the central longitudinal axis a of the housing 6 and the valve core. 7

In the following detailed description of individual components of the

Venting unit 3 will be the embodiment of these components with respect to their

Installation position in the mold segment 1 or the position in the figures considered, this applies, for example, terms such as outside or above and inside. The illustrated

Venting unit is an example of a venting unit with a diameter of 3.2 mm, therefore a venting unit for vulcanization molds for car tires.

Usually venting units may have a diameter (diameter adapted to the vent bore) of 2 mm to 5 mm.

The housing 6, shown separately in FIGS. 3a and 3b, is essentially a cylindrical sleeve with an inner diameter di which is constant over most of its extent along the central longitudinal axis a. The housing 6 has on its outer side an inner portion 6 a, which extends to the inside end of the housing 6 and has a length k which is at least 35% of the housing length 1. The section 6a has an outer diameter d ₂ , which by at least 0.3 mm, in particular to up to 0.5mm, is less than the inner diameter of the bore portion 2a. In both embodiments, the inner portion 6a passes over a 6 surrounding the housing inclined surface 6c in a further section 6b. The further section 6b extends in the embodiment shown in Fig. 3a to the outer and upper end of the housing 6. In the embodiment shown in Fig. 3b connects to the upper end of the housing 6, a narrow edge portion 6 ₁ , which from Section 6b is separated by an encircling on the housing 6, in cross section groove-shaped narrow portion 6d, wherein the outer diameter of the portion 6d in particular the

Outer diameter d _{2 of} the inner portion 6a corresponds. The edge section 6 _! has a length li of at least 1.0 mm. Both the section 6b (FIG. 3a, FIG. 3b) and the edge section 6b _! (FIG. ₃ b) have an outer diameter d ₃ which is larger by 0.3 mm to 0.5 mm than the outer diameter of the section 6 a and adapted to the inner diameter of the section 2 a of the venting bore 2 such that the section 6 b (FIG. Fig. 3a) or this and the edge portion 6bi (Fig. 3b) in the

Vent hole 2 can be pressed or can. Section 6b or the

Sections 6b and 6bi extend over a total length lb (FIG. 3a) or lb + lbi (FIG. 3b) from 30% to 45 of the housing length 1. The housing 6 can also have more than two sections. whose outer diameter is adapted in the manner mentioned to the inner diameter of the vent hole 2. The outer surface of the section 6b or to the central longitudinal axis a at an angle αι of 10 ° to 60 °, in particular from 15 ° to 45 ° to the housing 6 between the inner portion 6a and the adjoining portion 6b circumferentially encircling inclined surface 6c. The width bi of the inclined surface 6c is, for example, in the order of 0.20 to 0.30 mm. Another inclined surface 10 with an inclination inward is formed on the outside at the inner end of the housing 6. The inclined surface 10 is a kind chamfer on the housing edge and extends to the outside of the portion 6a and the central longitudinal axis a at a constant angle a ₂ , which is 10 ° to 60 °, in particular 15 ° to 45 °. The

Sloping surface 10 is very narrow, its width b ₂ is on the order of 0.15 to 0.20 mm. At the outer, the mold segment inside la side facing end portion of the housing 6 is provided on the inside with a frusto-conical widening 11, which on the

Embodiment of the valve disk 4, which, as for example, Fig. 2 shows, is also frusto-conical shaped adapted. The widening 11 is accordingly formed by an inner surface at the edge of the housing 6 encircling inclined surface I Ia, which extends to the central longitudinal axis a at an angle a ₃ of 10 ° to 45 °, preferably 15 ° to 30 °, in particular 22 °. The width b _{3 of} the inclined surface I Ia is in the

Order of magnitude of 0.5 mm.

On the truncated cone-shaped widening 11 opposite end portion of the housing 6 is a housing bottom 12, which has a central circular opening 13 with a central narrowest opening portion 13 a, whose

Inner diameter d _{4 is} smaller than the inner diameter di of the housing 6 and is circulated by a narrow ring. Above and below the opening portion 13a, the opening 13 is widened by means of an oblique surface 14, 15. The outside on the

Caseback 12 extending inclined surface 15 extends at an angle of a ₄ of 30 ° to 60 °, in particular of about 45 °, to the central longitudinal axis a. Housing inside forms the second inclined surface 14 in the embodiment shown a transition surface for

Housing inner wall and extends at an angle a ₅ of 30 ° to 70 °, in particular of the order of 60 °, to the central longitudinal axis a. The height hi of the housing bottom 12 parallel to the central longitudinal axis a is in the order of 0.4 mm to 0.6 mm.

The valve insert 7 will now be described in more detail with reference to Figures 2 and 4. 4 shows the valve stem 8, which consists of a cylindrical base section 8a with a constant diameter running over the major part of its extent, an end section 8b facing the inner side of the mold segment, on which the valve disk 4 is located, and one of the inner side of the mold segment

End section 8c composed. The end portion 8b has a subsequent to the valve plate 4, cylindrical holding portion 16a, which has a height h ₂ of 1.0 mm to 1, 5 mm and the diameter d _{5 is} greater than the diameter d _{6 of} the Base portion 8a and is adapted to the inner diameter of the helical compression spring 9 such that it can be firmly attached to the holding portion 16a and the inside of the valve plate 4 is supported. As shown in FIG. 2 shows the helical compression spring 9 at its attachable to the holding portion 16 a end at least two closely spaced turns 9 a, the mutual distance in the relaxed state of

Helical compression spring 9 highest half, in particular at most one third, corresponds to the mutual distance of the other turns. Such

"Double turn" may also be provided at the second end of the helical compression spring 9. The diameter d _{6 of} the base portion 8a is to the inner diameter d ₄ of

Opening portion 13a in the housing bottom 12 adapted. The diameter d ₆ of

Base portion 8a is at least 0.3 mm smaller than the inner diameter of the helical compression spring 9. Between the base portion 8a and the holding portion 16a is a centering 16b, which is an end portion 8b circumferential inclined surface, and the central central longitudinal axis a at an angle ß i from 10 ° to 20 °, in particular of the order of 15 °.

The second end section 8c is divided into two centrally by a slot 17 extending along the central longitudinal axis a and into the base section 8a. The slot 17 allows a compression or Aufeinanderzubewegen the two end portion parts 18 a, 18 b, so that the valve stem 8 through the constriction or the opening 13 in the circumferential

Projection 12 of the housing 6 performed and can be fixed to the housing 6. Each end portion portion 18a, 18b forms a projection, which is rounded according to the cylindrical shaft shape in each case in total. At its widest point, each projection on a collar 19 a, which via an inclined surface 19 b to the

Base section 8a connects. The inclined surfaces 19b extend at an angle β ₂ of 30 ° to 60 °, in particular of 45 °, to the central longitudinal axis a, wherein the angle ß ₂

preferably corresponds to the angle a _{4 of} the inclined surface 15 at the opening 13 in the housing bottom 12 of the housing 6, so that, as shown in FIG. 2, when the valve stem 8 is inserted, the inclined surface 19b is supported on the inclined surface 15 of the housing 6. The

End portion parts 18a, 18b taper in the direction of the shank end and on the outside have inclined surfaces 19c, each of which is inclined at an angle β ₃ of 15 ° to 25 °, in particular of 20 °, extend to the central longitudinal axis a and an insertion aid in

Insertion of the valve stem 8 in the housing 6 form. As shown in FIG. 2, when the valve stem 8 is inserted in the housing 6, the end portions 18a, 18b are located below the opening 13.

To assemble the venting unit 3, the helical compression spring 9 is positioned over the valve stem 8 and the valve stem 8 is guided by compressing the two end portion portions 18a, 18b through the central opening 13 in the projection 12 of the housing and secured to the housing 6. The inclined surfaces 14 above the

Opening portion 13a and the Schrägfiächen 19c on the valve stem 8 allow insertion with little effort.

In the embodiment shown in FIGS. 2 and 4, the valve disk 4 is designed with a flat outer surface. However, at least one elevation and / or at least one depression may be formed on the surface of the valve disk, with any surface area remaining flat outside the elevation or depression. The height of the elevation or elevations, in the vertical direction relative to a plane containing the circular edge of the valve disk, should preferably correspond to the highest stroke of the valve stem 8. Elevations and depressions can be designed almost arbitrarily, wherein preferably the recess (s) or elevation (s) with respect to at least one plane which contains the central central longitudinal axis a, symmetrically arranged or is or are. Elevations or depressions may be cuboid, in plan view star-shaped or circular and the like configured. Bumps have either a rounded surface or an outer surface which is parallel to the plane containing the circular edge of the valve disk.

5 and 6 show preferred embodiments of valve plates 4 ', 4 "on the basis of a partial region of the end section 8a of the valve stem 8. The valve plate 4' according to FIG. 5 has a convexity of the entire surface 4'a of the valve plate 4 '. towards the outside, the valve disk 4 "according to Fig. 6 has, as a depression, a curvature of the entire surface 4" a inwards be formed, wherein the height h ₃ or depth of the ball portion, compared to the plane containing the circular edge of the valve plate level is at most 30% of the radius of the underlying ball and not more than 0.50 mm. On the one hand by a survey or more surveys on the valve head the

Moving the valve disk to be supported in its closed position, on the other hand, by surveys and / or depressions on the valve disk targeted local

Wells or ridges on the tread of the tire are formed, which are visually perceived as less disturbing than the impressions of valve plates with a flat surface.

The venting unit 3 can be used in a precise and simple manner in the portion 2a of the vent hole 2 of the mold segment 1. After only the outer portion 6 a of the housing 6 is pressed into the vent hole 2, the housing 6 is positioned with its thinner portion 6 b in the vent hole 2. The inclined surface 10 at the lower end of the portion 6b assists easy insertion into the bore 2. This makes it possible to use the housing 6 also by machine without having a perfect alignment of the device, for example a robot, for drilling. By the longer thinner portion 6b, the housing 6 is pre-adjusted in the bore 2 and is substantially parallel to the bore axis when the inclined surface 6c comes into contact with the bore edge. Now the housing 6 is exactly centered and straightened so that the housing 6 is then introduced parallel to the bore axis without damaging or asymmetrically widening the bore edge. It is therefore not only a particularly accurate positioning of the venting unit 3 in the vent hole 2 allows, but it is also significantly reduced the effort. In principle, the venting unit 3 can be completely assembled from its parts before it is introduced into the venting bore. However, it is also possible to first introduce the housing 6 in the vent hole 2 and then to position the other parts in the housing 6. References list

1 mold segment la mold segment inside

2 breather hole

2a section

3 bleeding unit

4. 4 ', 4 "valve disk

5 treads

6 housing

6bi edge section

6a, 6b section

6c bevel

6d section

7 valve insert

8 valve stem

8a base section

8b, 8c end section

9 Schaubendruckfeder

9a turn

10 inclined surface

11 broadening

Ha beveled

12 caseback

13 opening

13a opening section

14. 15 inclined surface

16a holding section

6b centering 7 slot 18a, 18b. End section

19a. Bund

19b, 19c .Saw surface a .Mittelellängsachse bi, b ₂ , b ₃ width

di, d ₂ , d ₃ , d ₄ , d ₅ , d ₆ diameter 1 case length la, lb, lbl length

αι, a ₂ , a ₃ , 0 (4, a ₅ angle (housing) ßi, ß ₂ , ß ₃ angle (shaft)

depth

Claims

Patent claims

1. Ventilation unit (3) for a vulcanization mold of a pneumatic vehicle tire with a central central longitudinal axis (a), a cylindrical housing (6) which can be pressed into a vent hole (2) of the vulcanization mold and an im

Housing (6) positioned and movable relative to this valve insert (7), which has a valve stem (8) with a valve plate (4 ', 4") and a

Valve stem (8) surrounding helical compression spring (9), which is supported with one end on the housing (6) and with its other end on the inside on the valve plate (4 ', 4"), which on the outside is assigned to the vulcanization mold cavity, in plan view of one Has a circumferential surface (4'a, 4"a), the center of the circle being on the central longitudinal axis (a),

characterized,

that on the surface (4'a, 4"a) of the valve plate (4', 4") at least one

Survey and / or at least one depression is formed.

2. Venting unit (3) according to claim 1, characterized in that the height (h ₃ ) of the elevation or elevations, in the vertical direction relative to a plane containing the circular edge of the valve plate (4 ', 4"), is at most the stroke of the Valve stem (8) corresponds.

3. Ventilation unit (3) according to claim 1 or 2, characterized in that the depression or elevation is arranged or designed symmetrically with respect to at least one plane which contains the central central longitudinal axis (a). Venting unit (3) according to one of claims 1 to 3, characterized in that the elevation is a curvature of the entire surface (4'a) of the valve plate (4') towards the outside.

Venting unit (3) according to one of claims 1 to 3, characterized in that the recess is an inward curvature of the entire surface (4"a) of the valve plate (4").

Ventilation unit (3) according to claim 4 or 5, characterized in that the curvature is essentially spherical in shape, the height (h ₃ ) or depth (ti) of the spherical section being at most 30% of the radius of the

underlying sphere corresponds.