WO2014051528A1

WO2014051528A1 - The tire tread and the lamella for fixing into the vulcanization form for forming of the lamellar cut in the tire tread pattern block

Info

Publication number: WO2014051528A1
Application number: PCT/SK2013/050006
Authority: WO
Inventors: Jaroslav HAJDÚCH; Martin RYPÁK
Original assignee: Continental Matador Rubber, S.R.O.
Priority date: 2012-09-25
Filing date: 2013-09-24
Publication date: 2014-04-03
Also published as: EP2900491A1; SK500462012A3; SK288470B6; CN104640718B; CN104640718A

Abstract

The tire tread and the lamella for fixing into the vulcanization form for forming of the lamellar cut in the tire tread pattern block A lamellar cut of the tire tread consists of a main lamellar cut and perpendicularly arranged side lamellar cut, where the main lamellar cut contains in both opposite surfaces at minimum one row of 3D projections alternately arranged with depression in radial direction (OA, AB BC), which fit into projections of the opposite surface of the cut, and at minimum one flat part, which is perpendicularly intersected at minimum one said secondary lamellar cut.

Description

The tire tread and the lamella for fixing into the vulcanization form for forming of the lamellar cut in the tire tread pattern block

Technical field

An invention relating to construction of the vulcanization mould for making of winter, summer and/or all-season tires for passenger and cargo vehicles, whereas at the pressing process a lamella forms narrow cuts of the required shape and amount into tread pattern blocks on the tread part defined by a tread area of the tire. Tractions formed provide more effective transfer of forces at the contact of the tread with a road surface

State of the art

Tires designed for use on vehicles in winter period as well as during all seasons are characterized in addition to circumferential and transverse tread grooves also by a large number of narrow cuts formed by lamellas positioned in the tread part of the vulcanization mould cavity. The lamellas are made of sheet metal by moulding operations, from materials specified with purpose specified properties, such as corrosion resistance, strength and the like. They are unreleasably fastened in the mould ((milled mould, e.g. by gluing), secured against extraction during the mould opening phase. They are positioned in the radial direction with respect to the rotation axis of the tire. The lamellas can acquire the depths of tread grooves given by the tire profile, or it can vary depending on the requirements for the tread. A shape of the lamella when viewed in the radial direction can be composed from known curves (arc, line, parabola...) and form a certain shape (e.g. function sin, zig-zag...). The size and the shape are given by design, by desired properties and/or by size of pattern blocks. The lamellas used in one pattern can be identical or different in shape.

The lamellas by their number on winter and all-season tires form a high number of traction edges in order to enhance efficiency of force transmission at the point of pattern contact with the road surface. The fact can be utilized on wet, snow-covered and/or icy road surfaces.

During the tire and road interaction when forces are transferred a significant distortion of the tread block occurs. The deformation significantly affects drivability, it has a negative effect on driving stability, and influences a reaction rate of the tread. After decomposition of projection forces into the road plane the size of the deformation depends on the nature of the force working at that moment. It is apparent that deformation acquires values of all quadrants of the circle. Use of the block having no pattern cuts or grooves is the ideal solution in terms of the deformation in the road plane. As this case is undesired both from legal and technical aspects, the continuous block is necessary to be divided by narrow tread grooves. In order to increase traction properties it is necessary to divide the block by narrow cuts. That negatively affects rigidity of the block. Therefore, at present a variety of cut shapes are used: direct notches with variable depth, variously shaped, but most frequently in the shape resembling a course of the goniometric function sin. By shaping the cuts, rigidity of the block is increased, especially in axial direction and partly in tangential direction to the circumference of the tire. The phenomenon results in different distortion of the block in the longitudinal and transverse directions of the cut.

Recent findings evidence that various manufacturers have started using differently shaped cuts in order to achieve increased rigidity in all directions and even stress distribution in the tread block. By that, minimal deformation in the force transmission is achieved, response reaction speed to the input of the driver is increased, and so is the operation safety. Findings from currently known models of closed cuts are as follows:

3-D notches by Continental, described in European Patent Application EP 1 223 054 Al of January 12, 2001 shaped of a wave consisting of alternately spaced radii of different diameters positioned against each other. A lamella in its lower part transforms into opposite shape, where the curves of a small diameter are replaced by larger curves and vice verse. Modifications of the shape of such distribution can have a triangular shape or a rectangular quadrangle shape, or their combination. Variations in locking features will depend on the use of the shapes. The time lag in locking will occur.

A solution of Semperit described in patent US 5 350 001 dated September 27, 1994 depicts a sin function shaped cut changing into the shape shifted by ¼ of the wave length. Repetition in the radial direction depends on the shape and can take values of 2 or more. At value 2 a notch area is radially oriented at the point of intersecting the tire surface, at higher values there is an angular deviation from the radial direction. Solutions of compound triangular groove shapes have oriented differently edges. Patent EP 0 131 246 of Continental describes a zig-zag groove smoothly running from an upper curve into an identical one positioned in a lower part, being shifted by ¼ of its length.

International Patent Application WO 99/48707 of Goodyear describes a notch formed by a planar area having alternately positioned hemispherical recesses on one side and hemispherical protrusions on the other side, fitting into each other and alternately oriented to the notch axis. The solution caused strengthening of the tread block in all direction of the lamella plane. Due to the shape of protrusions locking occurred with a certain time lag.

The said document serves as a basis for the solution of Goodyear' s patent EP 1 533 141 Al, in which projections from the notch plane and fluently following openings are regularly spaced. Their shape can be triangular, rectangular, ... up to x-angular in their section. By the solution Goodyear partially eliminates the lag and the start of locking is sharper.

Definitions

Axial direction - is the direction given by the automobile tire rotation axis

Radial direction - is the direction given by the normal axis to the tire circumferential circle and to the rotation axis thereby simultaneously intersected

Tangential direction - is the direction given by a tangent to the circumferential circle

Lamella - is a part pressed from a sheet metal, a material of required properties, of a defined thickness, firmly, unreleasably connected with a mould cavity in the tread part giving the shape and dimensions of narrow cuts in tread blocks

Subject-matter of the invention

A tire tread containing at minimum one row of tread blocks arranged in the circumferential direction of the tire, whereas at minimum one of the blocks is provided by one or more 3D shaped lamellar cuts in radial direction, and that shaped lamellar cut is defined by mutually fitting shaped surfaces formed by the lamella during vulcanization, which subject-matter is that the lamellar cut consists of the main lamellar cut and perpendicular (or under an angle resulting from required properties) arranged secondary lamellar cut, where the main lamellar cut contains in both opposite surfaces at minimum one row of 3D projections alternately arranged with the depressions in radial direction (OA, AB BC), which fit into projections of the opposite surface of the cut, at minimum one flat part, which is perpendicularly (or under the angle resulting from the required properties) intersected by at minimum one said secondary lamellar cut.

In a preferred embodiment, the main lamellar cut contains two rows of projections alternately arranged with three flat parts, each of which is provided with secondary lamellar part, whereas the projections and depressions of the bands of the main lamellar cut are shaped as the periodically repeated element in the radial direction at interval 0C, which is formed by the sum of intervals OA, AB and BC, whereas at interval AB the shape is interrupted and replaced by an identical periodically repeated function shifted by one half of the period and at interval BC it regains its original shape, whereas the plane defining the size and shape of the projections, indented from the central plane has a shape of the resulting curve of the bending of the clamped beam on each cut surface, in the axial direction. At the same time, each secondary lamellar cut is symmetrically arranged to the main 3D lamellar cut, which divides it into two halves.

The secondary lamellar cut can be formed by a smooth flat lamella, or it can also contain 3D elements, which are axially oriented. It is preferred if the 3D element on one half of the secondary lamellar cut is oriented opposite to the 3D element on the other half of the secondary lamellar cut. Both halves of the secondary lamellar cut can be slightly bevelled at interval BC.

Another subject-matter of the invention is a lamella formed by a combination of the main 3D lamellar part and at minimum one secondary lamellar part, whereas the secondary lamellar part crosses the main 3D lamellar part and is positioned perpendicularly to the main 3D lamellar part, where the main 3D lamellar part is formed as an extension of the periodically repeated shape to the distance equal to the length of interval 0C, which is formed by the sum of intervals OA, AB and BC, whereas the extension of the periodically repeated element is arranged in rows LI, L2 in radial direction, where at interval AB the shape is interrupted and replaced by identical periodically repeated function shifted by one half of the period and at interval BC it regains its original shape, and where alternately with rows LI, L2 flat parts PI, P2, P3 are formed, which contain perpendicularly (or (or under the angle resulting from the required properties) arranged secondary lamellar part, and whereas the plane defining the size and shape of the projections, indented from the central plane has a shape of the resulting curve of the bending of the clamped beam as viewed in axial direction and when viewed in radial direction it has a shape consisting of curves selected from the following group: arc, straight line, parabola, hyperbola and/or it forms the pattern of the function sin, zig-zag, zig-zag with truncated points.

The main 3D lamellar part can contain 2 to 4 rows LI, L2 in radial direction, formed by extension of periodically repeated element to distance 0C, where at interval AB the shape is interrupted and replaced by identical periodically repeated function shifted by one half of the period and at interval BC it regains its original shape.

Under the preferred embodiment the main 3D lamellar part can divide the secondary lamellar part to two identical halves.

The secondary lamellar part can be flat or it can be provided by at minimum one axially oriented 3D element in each of its halves.

In another preferred embodiment interval OA : AB : BC can be in proportion of 1/3 / 1/3 / 1/3 or another, such as 0,4:0,3:0,3 with the biggest interval of the first order).

According to a preferred embodiment the lamella consists of two radially arranged rows LI, L2 of projections and depressions of the periodically repeated element at interval 0C, where the main 3D lamellar part is formed as the extension of the periodically repeated shape to the distance equal to the length of interval 0C, where at interval AB the shape is interrupted and replaced by an identical periodically repeated function shifted by one half of the period and at interval BC it regains its original shape, and where between individual rows LI, L2 flat parts PI, P2, P3 are formed, on which the secondary lamellar part is fixed perpendicularly, and whereas the area defining the size and shape of the projections in rows LI and L2 of the main lamellar part, indented from the central plane, has the shape of the resulting curve of the bending of the clamped beam from the view in axial direction and from the view in radial direction it has the shape consisting of the curves selected from the following group: arc, straight line, parabola, hyperbola and /or it forms the pattern of the function sin, zig-zag, zigzag with truncated points.

In order to simplify the description, the body of the lamella will be described merely as a surface consisting of neutral axis during the bending process of the lamella. Radii essential for thin-walled extract production technologies will not be considered. The body of the lamella is then formed by a layer of evenly coated material given the neutral surface in the direction of each side of the surface (wall thinning due to the forming process is not considered). Recognized in the art, and by the element geometry it is obvious that lamella type of periodically repeating elements are capable of providing an appropriate force transfer in axial direction. When transferring forces in the tangential direction increased deformation of the pattern blocks occurs (formed lamellas have a more favourable effect on rigidity in tangential direction compared to flat lamellas).

Therefore, the invention is based on a combination of the flat lamellas and the lamella of a periodically repeating element in precise number (depending on geometry of the block and desired properties), whereas in the radial direction the shape is discontinued and replaced by the shape of identical periodically repeated element shifted by one half of the period. That prevents long relative movement between individual parts of the tread pattern block and transmission of braking and traction forces, and of movement in curves. Having regarded the block deformation character, which can be considered as the clamped beam, the plane defining the size and shape of the projections, indented from the central plane, will have the shape of the final curve of the beam bend. By that the locking function of the unworn tread is provided. By the shape more even effect of the lamella cuts on a road between individual states of tread wear is achieved, using sin shaped lamellas was unfavourable for worn tread and decreased the traction ability and pattern block deformation. Location of the lamella slots provided a lack of traction edges in axial direction and increased rigidity of the block unable to adapt to smaller surface roughness, further branches in the shape of the positions intersecting the main lamellar slots were added to the lamella. Number and distribution of the branches is given by the shape and deformation of the tire tread pattern block, 3D element eliminating mutual shifting of the block in the intersection is added to the branches. The element may be omitted. Another advantage compared to previously used lamellas is reduction of locking time caused by the horizontal surface of projections, so is the increased rigidity of the pattern block, substantial start of locking, more favourable course of pattern block wearing-off, better transfer of forces when changing motion conditions due to limitation of mutual shifting of individual parts of the tire tread pattern blocks in radial and axial directions resulting in enhanced safety as well as driving comfort. The described lamella is shown on Fig. 1.

A lamella is formed by moulding of a sheet material. Three-dimensional pressed parts designed to be placed in the mould cavity are formed, helping to create a cut in the pattern block of the tread. The lamella axis is identical with the neutral axis of the pressed part. A shape of the lamella is depicted on Fig. 1, and it is formed as an extension of a periodically repeated shape to a distance equal to the length of interval 0C, at interval AB the shape is discontinued and replaced by an identical periodically repeated function shifted by one half of the period. At interval BC the lamella regains its original shape.

At the place of surface discontinuance (points A and B) the lamella surfaces are limited in the radial direction and closed by surfaces intersecting points A and B and in points D and E they are under angle alpha and beta towards the side surface 13, which corresponds with the shape of the resulting curve of the bending of the clamped beam. Interval OA : AB : BC is preferred in proportion 1/3 / 1/3 / 1/3, or in another proportion such 0,4:0,3:0,3 with the biggest interval of the first row. It can be changed in case of other required properties.

From the plan view of the lamella the main 3D lamellar part is formed from metal the sheet with projections at intervals LI, L2 and intervals PI, P2, P3 are without deformation. There is a space for placing a transverse side lamellar part. A number of projections at intervals LI, L2 depends on geometry of the block, the most preferred being number 2.

Brief description of drawings

On the attached drawings figures 1 and 4 depicts a perspective view on the lamella under the invention. Fig. 2 shows a curve of the bending of the clamped beam. Figure 3-1 depicts a front view on the lamella, on Fig. 3-2 there is the side view and on figure 3-3 is a top view of the lamella. Figures 4-1 to 4-3 depict sections through the lamella marked on figure 4. Figures 5-1 to 5-3 depict one pattern block of the tire tread in various states of wear.

Exemplary embodiment of the invention

The lamella suitable for fixing inside the vulcanization mould in order to form lamellar cuts in the tire tread pattern block is depicted on Fig. 1 and Fig. 2-2, where intervals OA, AB and BC are marked. The main 3D lamellar part contains two rows LI and L2 of shaped projections and depression formed as the extension of the periodically repeated shape to the distance equal to the length of interval 0C in radial direction. At interval AB the shape is discontinued and replaced by the identical periodically repeated function shifted by one half of the period and at interval BC it regains its original shape. The area defining the size and shape of the projections in rows LI and L2, indented from the central plane, has the shape of the resulting curve of the bending of the clamped beam in axial view. The curve is depicted on Fig. 2. In radial view the cut has the shape consisting of the curves selected from the group of: arc, straight line, parabola, hyperbola and/or it form the pattern of the function sin, zig-zag, zigzag with the truncated points as shown on figures 5-1 to 5-3. Between individual rows LI and L2 flat parts PI, P2, P3 on the main 3D lamellar part are formed. In the middle of each flat part a side lamellar part is fixed crossways while they form a right angle with the main lamellar part. The main 3D lamellar part divides the side lamellar part into two identical halves. Each half of the side lamellar part is provided with the 3D element, approximately at interval BC. In axial direction the 3D elements are oriented mutually opposite direction.

Claims

P A T E N T C L A I M S

1. Tire tread containing at least one row of the pattern blocks arranged in the circumferential direction of the tread, while at least on of these blocks is equipped with one or more 3D shaped lamellar cuts in the radial direction, and this shaped lamellar cut is defined by the mutually fitting shaped surfaces formed by the lamella during the vulcanization, c h ar a c t eri z e d i n th at the lamellar cut consists of the main lamellar cut and the perpendicular side lamellar cut, wherein the main lamellar cut contains at its both adjacent surfaces at least one row of 3D projections alternatively arranged with the depressions in the radial direction (OA, AB BC), which depressions fit the projections of the opposite surface of the cut; and at least one flat part perpendicularly intersecting at least one of said side lamellar cuts.

2. Tire tread according to claim 1, characterized in that the main lamellar cut contains two rows of the projections alternatively arranged with three flat parts, of which each is equipped with the side lamellar cut, while the projections and depressions of the strips of the main lamellar cut have the shape of the periodically repeated element in the radial direction with interval 0C, which interval is formed by the summary of intervals OA, AB, and BC, while at AB interval the shape is interrupted and substituted by the same periodically repeated function shifted by one half of the period, and it regains its original shape at BC interval; while the area defining the size and shape of the projections, indented from the central plane, has the shape of the resulting curve of the bending of the clamped beam at each cut surface, in axial view.

3. Tire tread according to claims 1 or 2, characterized in that each side lamellar cut is symmetrically arranged in relation to the main 3D lamellar cut dividing it to two halves.

4. Tire tread according to any of claims 1 to 3, characterized in that the side lamellar cut contains axially oriented 3D element at each half, while 3D element at one half of the side lamellar cut is oriented reversely in relation to 3D element at another half of the side lamellar cut.

5. Lamella suitable for fixing into the vulcanisation form for forming of the lamellar cut in the pattern block of the tire tread according to claims 1 to 4, characterized in that, it is formed by the combination of the main 3D lamellar part and at least one side lamellar part, while the side lamellar part intersects the main 3D lamellar part and is perpendicular to the main 3D lamellar part, where the main 3D lamellar part is created as the extension of the periodically repeated shape up to the distance equal to 0C interval length, which interval is created by summary of intervals OA, AB, and BC; while the extension of the periodically repeated element is arranged in rows LI, L2 in radial direction, where at AB interval the shape is interrupted and substituted with the same periodically repeated function shifted by a half of the period, and at BC interval it regains its original shape; and where the individual rows LI, L2 alternate with the flat parts PI, P2, P3 containing perpendicularly (optionally under the angle following from the desired characteristics) arranged side lamellar part; while the plane defining the size and shape of the projections, indented from the central plane has the shape of the resulting curve of the bending of the clamped beam from the axial view; and from the radial view it has the shape consisting of the curves selected from the group of: arc, straight line, parabola, hyperbola and/or it form the pattern of the function sin, zig-zag, zig-zag with the truncated points.

6. The lamella according to claim 5, characterized in that the main 3D lamellar part contains 2 to 4 rows LI, L2 in the radial direction, created by the extension of the periodically repeated element at the distance of 0C, where at AB interval the shape is interrupted and substituted by the same periodically repeated function shifted by a half of the period, and at BC interval it regains its original shape.

7. The lamella according to claims 5 or 6, characterized in that the main 3D lamellar part divides the side lamellar part into two halves.

8. The lamella according to claim 7, characterized in that the side lamellar part is flat.

9. The lamella according to claim 7, characterized in that at least one side lamellar part is equipped with at least one axially oriented 3D element at each half.

10. The lamella according to any of claims 5 or 6, characterized in that interval 0A:AB:BC is of proportion 1/3:1/3:1/3.

11. The lamella according to any of claims 5 or 6, characterized in that interval 0A:AB:BC is of proportion 0.4:0.3:0.3 with the biggest interval of the first order.

12. The lamella according to any of the preceding claims, characterized in that it is formed by two radially arranged rows LI, L2 of the projections and depressions of the periodically repeated element in 0C interval, where the main 3D lamellar part is formed as the extension of the periodically repeated shape up to the distance equal to the length of OC interval, while the shape is interrupted at AB interval and substituted with the same periodically repeated function shifted by half of the period, and at BC interval it regains its original shape; and where the individual rows LI, L2 alternate with the flat parts PI, P2, P3 containing perpendicularly fixed side lamellar part; and while the plane defining the size and shape of the projections of LI and L2 rows of the main lamellar part, indented from the central plane, has the shape of the resulting curve of the bending of the clamped beam from the axial view; and from the radial view it has the shape consisting of the curves selected from the group of: arc, straight line, parabola, hyperbola and/or it forms the pattern of the function sin, zig-zag, zigzag with the truncated points.