Method for producing a mould segment of a vulcanizing mould, mould segment, and vulcanizing mould

Abstract

A method for producing a mold segment of a vulcanizing mold for a pneumatic vehicle tire for forming the profiling of a tread, having a metallic base part (6) with a mold side with ribs (3) which form channels encircling or delimiting profile elements. A rib skeleton (8) consisting of ribs (8), the arrangement and the profile of which at least partially corresponds to the arrangement and the profile of ribs (3) forming channels, is milled from the base part (6), inserts (7) with peripheral frame parts (7b) are built up by means of an additive method, the inserts (7) being inserted into the rib skeleton (8) and the frame parts (7b) completing the ribs (8) of the rib skeleton (8) to form the ribs (3) forming the channels.

Claims

1. A method for producing a mold segment of a vulcanizing mold for a pneumatic vehicle tire, the mold segment being configured to form the profiling of a tread of the tire, the method comprising: providing a metallic base part having a mold side; milling a rib skeleton into the mold side of the base part, the rib skeleton comprising ribs arranged and profiled so as to correspond with channels of the profiling of the tread in which said channels encircle or delimit profile elements of the profiling of the tread; building inserts with frame parts using an additive manufacturing process; and inserting the inserts into the rib skeleton, wherein the ribs of the rib skeleton in combination with the peripheral frame parts of the inserts form overall ribs that define the channels encircling or delimiting the profile elements of the profiling of the tread.

2. The method of claim 1, wherein the building of the inserts includes building lamellae and/or micro-lamellae within the peripheral frame parts by using additive manufacturing.

3. The method of claim 1, wherein the inserts are built on a building plate and subsequently cut out of the building plate to form bottom plates of the inserts.

4. The method of claim 1, wherein the inserts are built with inner layers that form bottom plates of the inserts during the additive manufacturing process.

5. The method of claim 4, wherein the inserts are built on a building plate and the forming the bottom plates includes cutting the inner layers from the building plate after the additive manufacturing process.

6. The method of claim 5, wherein the inserts comprise at least one surface structure configured to define profile details of the profiling of the tread.

7. The method of claim 1, further comprising additively building shoulder decoration ribs as part of the inserts.

8. The method of claim 1, further comprising milling out the base part to form shoulder decoration ribs on the mold side.

9. The method of claim 1, further comprising milling out the base part between the ribs of the rib skeleton to correspond to an intended outer contour of the tire tread.

10. The method of claim 9, further comprising making ventilation holes in the base part.

11. The method of claim 10, further comprising providing a building plate with ventilation holes aligned to the ventilation holes in the base part.

12. The method of claim 1, wherein the inserts are built up-leaving holes free that correspond to ventilation holes in a building plate.

13. The method of claim 1, wherein depressions in the base part are milled with rounded corner regions, the inserts being built up with correspondingly rounded outer corner regions.

14. The method of claim 1, wherein the ribs of the rib skeleton define enclosed pockets of the base part, and the inserts are nested within the enclosed pockets in such a way that the ribs of the rib skeleton cooperate with the peripheral frame parts of the inserts to form the overall ribs.

Description

(1) Further features, advantages and details of the invention will now be described in more detail with reference to the partially schematic drawing, which illustrates exemplary embodiments. In the drawing:

(2) FIG. 1 shows a view of a mold segment part of a tire vulcanizing mold consisting of a base part together with inserted inserts,

(3) FIG. 2 shows a view of the associated base part,

(4) FIG. 3 shows a view of the associated inserts,

(5) FIG. 4 shows a schematic view of a building plate with built-up inserts,

(6) FIG. 5 shows a schematic view of inserts cut out of the building plate,

(7) FIG. 6 shows a schematic view of an individual insert, and

(8) FIG. 7 shows a view of a detail of an insert inserted into a base part.

(9) In the description below, radial direction is understood as meaning the direction of a perpendicular to the mold surface forming the tread outer surface. Axial direction is understood as meaning a direction parallel to the axis of rotation of the tire to be vulcanized.

(10) FIG. 1 shows a view of a mold segment part 1 of a mold segment of a segment ring of a tire vulcanizing mold, wherein in particular the inner sidethe side facing the mold cavitycan be seen. A conventional segment ring is composed, for example, of seven to fourteen mold segments, each of which has a mold segment spine opposite the inner side, by means of which the mold segments are arranged in a manner known per se on a segment shoe of the tire vulcanizing mold. On its inner side, the mold segment part 1 has mold elements which, according to the profiling provided in the tread of the tire to be vulcanized, are profile negative elements, ribs 3 and lamellae 4 in the embodiment shown.

(11) The rear sides of the mold segment parts 1 are, for example, simple cylindrical surfaces, and therefore the mold segment parts 1 are attached to the segment shoe of the vulcanizing mold by means of appropriately designed adapters. Use is made in particular of adapters which are screwed onto the rear sides of the mold segment parts 1 or are connected to the mold segment parts 1 via tongue and groove or dovetail connections or other positive or materially bonded connections. In an alternative embodiment, the mold segment parts 1 themselves are already designed as an interface to the container of the vulcanizing mold.

(12) The lamellae 7 form sipes in the tread of the tire to be vulcanized with a width (on the tread periphery in a new tire) of the order of magnitude of 0.4 mm to 1.0 mm, the ribs 3 form channels in the tread of the tire to be vulcanized, the width of which (on the tread periphery in a new tire) is greater than 1.0 mm and in particular up to 6.0 mm. In addition, it is possible to provide lamellae which are what are referred to as micro-lamellae, which usually form narrow and shallow sipes with a width and depth of about 0.2 mm to 0.3 mm in the tread. In the embodiment shown in FIG. 1, the ribs 3 and lamellae 4 form a typical winter tire profile in the tread of the tire to be vulcanized. In the example, a large number of V-shaped ribs 3 running parallel to one another and across the width of the inner side of each mold segment part 1 are also provided, and there are also further ribs 3 running obliquely to the circumferential direction of the mold segment 1 and subdividing the V-shaped ribs 3. On the shoulder side, there is an additional division by means of ribs 3 which are present centrally between and parallel to the sections of the V-shaped ribs 3 running on the shoulder side. Shoulder decoration ribs 2 form the lateral edges of the mold segment part 1. In all of the surface elements encircling the ribs 3 and the shoulder decoration ribs 2 there is in each case a number of lamellae 4 in wave form. Flat structures in the form of decorative elements 5 for forming shoulder decorations of the tire are located on the upper side of the shoulder decoration ribs 2the side of the mold segment part 1 facing the mold cavity. Owing to the V-shaped ribs 3 between the shoulder decoration ribs 2, the profile negative which is formed is divided into pitches running in a V-shaped manner relative to one anothernegative sections that are repeated in the same way in the circumferential direction in each half of the mold segment part.

(13) As shown in FIG. 2 and FIG. 3, the mold segment part 1 is composed of a base part 6 made of a metallic material, in particular of a steel alloy or an aluminum alloy, and also of a multiplicity of inserts 7 inserted into the base part 6. The inserts 7, the production of which will be described in more detail further below, each have a bottom plate 7a (FIG. 6) which has a flat underside and an inner side formed in accordance with the outer surface of the blocks to be formed in the tread of the tire to be vulcanized. The bottom plates 7a have a thickness d, which is slightly larger at the periphery than in the center. The inner sides of the bottom plates 7a therefore form the mold surfaces for forming the outer surfaces of the tread that come into contact with the underlying surface.

(14) The design of the base part 6 will now be explained in more detail with reference to FIG. 2. The base part 6 is a milled part with milled shoulder decoration ribs 2 with milled decorative elements 5 on the lateral edges and a milled rib skeleton 8. The rib skeleton 8 consists of ribs 8, the arrangement and the profile of which corresponds to the arrangement and the profile of the ribs 6, although the ribs 8 are narrower than the ribs 6, and flank sections of the ribs 6 are missing on both rib flanks 8a. As will be described later, these flank sections are supplemented by frame parts 7b of the inserts 7. According to a preferred embodiment, the rib flanks 8a are, as shown in FIG. 2, flat surfaces which are oriented in the radial direction. In principle, the rib flanks 8a are milled in such a way that a flush insertion of the inserts 7 mentioned from above is possible; the rib flanks 8a can therefore be slightly inclined relative to the radial direction, for example.

(15) The level of the tips of the ribs 8 corresponds to that of the ribs 3. However, the ribs 8 have a greater height than the ribs 3, since the ribs 8 of the rib skeleton 8, on the shoulder side together with the shoulder decoration ribs 2, enclose deeper milled-out depressions with flat bottom surfaces 9. The depth of the depressions is adapted to the greatest thickness d of the bottom plates 7a of the inserts 7 in such a way that, when the inserts 7 are inserted, the inner sides of the inserts 7 forming the mold surface are located at the intended mold surface level.

(16) The orientation of the bottom surfaces 9 is adapted to the desired rounding or contour of the outer side of the tread of the tire to be vulcanized, preferably by each bottom surface 9 being aligned at right angles to a straight line oriented in the radial direction, with respect to the outer contour mentioned, through the geometric center point thereof. The bottom surfaces 9, which are oriented virtually in the axial direction, are therefore located in the central region of the base part 6.

(17) The decorative elements 5 on the shoulder decoration ribs 2 have, for example and as shown in FIG. 1 and FIG. 2, flat and narrow elevations which continue the ribs 8 of the rib skeleton 8.

(18) For ventilation, the base part 6 is pierced between the bottom surfaces 9 and its rear side, with either in each case a larger number of holes 11a being created per bottom surface 9 (FIG. 2) or only one or two holes 11a being created for ventilation, and a type of channel network of flat depressions, connected to the hole 11a or the holes 11a, being milled on the respective bottom surface 9. The holes 11a are arranged in such a way that their positions do not coincide with the positions of the lamellae 4 in the inserts 7.

(19) The inserts 7 are built up in a larger number on a building plate 10 by an additive method, in particular by selective laser melting. The building plate 10 is a flat plate, and, in a preferred embodiment, the thickness of the plate also determines the required depth of the mentioned depressions in the base part 6. The building plate 10 is first also provided with holes 11b (FIG. 4 and FIG. 5) corresponding to the arrangement of the holes 11a in the base part 6. Depressions in the form of channel networks, which correspond to the milled channel networks that may be provided on the bottom surfaces 9, may be formed, but this is not absolutely necessary, since the milled channel networks on the bottom surfaces 9 usually already ensure good ventilation.

(20) The building plate 10 is aligned and positioned accordingly in a 3D printer, and the holes 11b created are filled with metal powder or the like flush with the upper side of the building plate 10. The individual inserts 7 are then built up layer by layer in their intended designs, together with the provided lamellae, any micro-lamellae, other surface structures, optionally letters, treadwear indicators, etc. Ventilation holes are left free at the positions of the holes 11b in the building plate 10. A thin inner layer 12 (FIG. 4) is preferably built up on the upper side of the building plate in a curved manner corresponding to the intended curvature of the mold surface. The inserts 7 are also built up with peripheral frame parts 7b (FIG. 6), which are designed in such a way that, when the inserts 7 are inserted at their intended positions on the base part 6, the ribs 8 of the rib skeleton 8 are supplemented to form complete ribs 3. In the case of inserts 7 that are to be positioned on the shoulder side, frame parts 7b are formed only on those three sides that border ribs 8. Depending on the actual design of the tread profile with ribs, associated inserts that shape the profiling can also only have frame parts on two sides and/or be designed in such a way that they form larger profile blocks, more than one profile block or other block-like structures in the tread.

(21) In a preferred embodiment, the built-up inserts 7 together with the building plate part, on which they are directly built up, are cut out of the building plate 10, for example by means of a laser beam, water jet or mechanically. The mating surfaces are reworked if necessary. At this point, ventilation valves, if provided, can be inserted in the holes 11b penetrating the building plate 10 and the inner layer 12. The bottom plates 7a of such inserts 7 consist of the building plate part and the inner layer 12. In an alternative embodiment, the inserts 7 are separated along the upper side of the building plate 19, for example are cut off, such that the bottom plates 7a are formed by the inner layers 12. The milling depth of the depressions in the base part 6 depends on the intended design.

(22) The positioning and insertion of the inserts 7 at their positions on the base part 6 subsequently takes place. The inserts 7 are fixedly connected to the base part 6, preferably by shrinking, by the base part 6 being heated before insertion. The inserts 7 can also be connected to the base part 6 by screwing or welding. In an embodiment with building plate parts as constituent parts of the bottom plates 7b of the inserts 7, screw holes with internal threads can be created in the building plate and the base part, such that inserts 7 can be easily exchanged.

(23) Milling out the depressions in the base part 6 with sharp-edged corners is expensive. The corner regions of the depressions are therefore preferably milled in a rounded manner. The corner regions between the frame parts 7b on the inserts 7 are built up in rounded form on the outer side, corresponding to the rounded corner regions of the depressions, during the additive building-up method, and the inner corners between the frame parts 7b are built up with sharp edges, as shown in FIG. 7.

(24) In particular, the mold segment division takes place in such a way that complete inserts can be used. Alternatively, there is a division of inserts in the data for the additive building-up method, such that inserts are additively built up in two parts.

(25) Furthermore, inserts 7 themselves can additionally have ribs which, for example, subdivide these inserts 7 or divide them into insert elements. The rib skeleton 8 can have ribs which are interrupted in their profile and which supplement frame parts of the inserts.

(26) The additive building up of the inserts takes place fully automatically with software control, as does the milling work on the base parts 6.

LIST OF REFERENCE SIGNS

(27) 1 . . . Mold segment 2 . . . Shoulder decoration rib 3 . . . Rib 4 . . . Lamella 5 . . . Decorative elements 6 . . . Base part 7 . . . Insert 7a . . . Bottom plate 7b . . . Frame part 8 . . . Rib skeleton 8 . . . Rib 8a . . . Rib flank 9 . . . Bottom surface 10 . . . Building plate 11a, 11b . . . Hole 12 . . . Inner layer d . . . Thickness