WO2021254663A1

WO2021254663A1 - A method for manufacturing a transverse segment for a drive belt

Info

Publication number: WO2021254663A1
Application number: PCT/EP2021/025212
Authority: WO
Inventors: Dave VAN DEN HEUVEL; Michael Marinus Wilhelmus DOGGE; Michel VAN DONGEN; Adrianus Antonius Jacobus Maria VAN TREIJEN; Guillaume Gerard Hubertus Rompen
Original assignee: Robert Bosch Gmbh
Priority date: 2020-06-19
Filing date: 2021-06-18
Publication date: 2021-12-23
Also published as: NL1043699B1

Abstract

The invention concerns a method for manufacturing a transverse segment (10) for a drive belt (3) that is composed of a multitude of such transverse segments (10) mounted on and along the circumference of a ring stack (11), which method includes at least the process steps of blanking the transverse segment (10) from steel basic material and of quench hardening the blanked transverse segment (10). According to the invention the method further includes a process step of either grinding or bending at least a bottom part of the transverse segment (10) that defines a pulley contact surface on either side thereof in width direction, for setting an angle of divergence between these pulley contact surfaces in thickness direction to a desired value.

Description

A METHOD FOR MANUFACTURING A TRANSVERSE SEGMENT FOR A DRIVE BELT

This invention relates to a transverse segment that is destined to be part of a drive belt for a continuously variable transmission with two pulleys and the drive belt. Such a transmission is commonly known and is, for example, applied in the drive train of passenger cars and other motor vehicles. In the transmission the drive belt runs around and between the pulleys that are each provided with two conical discs that define a V- groove wherein a respective circumference part of the drive belt is held. The width of the V-groove of the pulleys can be changed in mutually opposite directions, by moving the pulley discs towards, respectively away from one another, to control a radius at which the drive belt is (effectively) in friction contact with the respective pulleys, i.e. to control a speed ratio provided by the transmission within a continuous range between a smallest and a largest speed ratio.

A known type of drive belt comprises an essentially contiguous row of transverse segments made of steel that are mounted on and around the circumference of a ring stack composed of a number of mutually nested flexible endless bands or rings that are likewise made of steel, in particular a maraging steel. At each pulley, the transverse segments are clamped between a respective pair of conical discs of the respective pulley that are urged towards each other. For taking up such clamping forces, i.e. for arriving in friction contact with the pulleys, the transverse segments are each provided with a respective pulley contact surface on either (axial) side thereof, which pulley contact surfaces are mutually oriented at an angle that essentially corresponds to the an angle between the pulley discs.

The clamping forces exerted on the transverse segments include a radially outward oriented force component, such that at the pulleys the transverse segments follow a curved trajectory, while bearing against the radial inside of the ring stack through, at least, a part of the surface of their base part that is located between the pillar parts, which surface part is denoted a bearing surface hereinafter. Hereby, the ring stack is tensioned such that is extends essentially straight between the two pulleys, while guiding the transverse segments as these traverse from the one pulley to the other in such straight trajectory parts. With this type of drive belt, torque is transmitted between the pulleys by, at least in part, the successive transverse segments pushing each other forward from the one pulley to the other while sliding along and being guided by the ring stack.

In the above and below description, the axial, the radial and the circumference directions are defined relative to the drive belt when placed in a circular posture. A thickness direction and a thickness dimension of the transverse segments are defined in the said circumference direction, a height direction and a height dimension of the transverse segments are defined in the said radial direction and a width direction and a width dimension of the transverse segments are defined in the said axial direction. A thickness direction and a thickness dimension of the rings and of the ring stack are defined in the said radial direction, a width direction and a width dimension of the rings and of the ring stack are defined in the said axial direction and a length direction and a length dimension of the ring stack is defined in the said circumference direction. Up and down directions and above and below positions are respectively defined in radial outward and radial inward.

The known drive belt comes in two basic designs. In one basic design thereof, the ring stack is provided in two parts, i.e. as two ring sets that are each accommodated in a respective one of two, axially oriented recesses defined by the transverse segments, while allowing the transverse segments to move along the circumference thereof. The axial recesses of the transverse segments are provided on either side of a central or neck part thereof, between a bottom or body part located radially inward of the ring stack and a top or head part located radially outward of the ring stack. This one basic design is a/o known from the United States patent application publication US 2015/0285336 Al.

In an alternative basic design of the drive belt, the transverse segments thereof each define a central opening that is open towards the radial outside of the drive belt for accommodating the ring stack, while allowing the transverse segment to move along the circumference thereof. This central opening is defined by and between a base part of the transverse segment that is located radially inward of the ring stack and two pillar parts thereof that respectively extend from a respective side of the base part in radial outward direction. The two pillar parts thus define respective axial boundaries of the central opening, whereas in radial inward direction the central opening it is bounded by the base part. In radially outward direction the central opening is at least partly closed by some means, in order to confine the ring stack to the central opening. This particular type of drive belt is, for example, known from the British patent GB1286777-A and, more recently, from the international patent publication WO2018/210456-A1. It is noted that according to these documents, the said means for confining the ring stack in radial outward direction are embodied by respective hook portions of the pillar parts that each extend axially towards the respectively other, i.e. axially opposite, pillar part at some distance away from the base part. These hook portions of the transverse segment can have equal axial extent or such axial extent can be different between the two hook portions, in which case these respective hook portions are preferably provided on opposite sides of the transverse segment for successive transverse segments in the drive belt, as a/o taught by WO2018/210456-A1. As seen in radial direction, an outer portion of the known transverse segment is provided with an essentially constant thickness, whereas a thickness of an inner portion thereof decreases in radially inward direction. In between the said inner and outer portions, a front surface of the transverse segment, facing in a circumference direction of the drive belt, includes a width-wise extending surface part that is curved in radial direction and that is often referred to in the art as a rocking edge or a tilting zone. The rocking edge allows successive transverse segments in the drive belt to mutually rotate about the axial direction, while these remain in contact at the rocking edge, whereby the drive belt as a whole follows a curved trajectory. Although the rocking edge can be located in the body part of the transverse segment, in case of the latter, alternative basic design of the drive belt it is preferably located at least partly in the pillar parts of the transverse segment. In this case, the rocking edge consists of two separate sections that are mutually separated by the central opening.

Although these are not yet present in GB1286777-A, it has become common practice in the art to provide the transverse segment with a protrusion projecting from the said front surface or from an oppositely facing rear surface thereof and with a corresponding, however somewhat larger cavity in its respectively opposite main surface. In the row of transverse segments in the drive belt, the protrusion of a first transverse segment is received in the cavity of a second, successive transverse segment, at least in part. Hereby, a mutual displacement of the respectively successive transverse segments perpendicular to the circumference direction of the drive belt is limited to a play of the protrusion inside the cavity. The protrusions and cavities thus serve to both mutually align the transverse segments in a row in the straight parts of the drive belt’s trajectory and to limit a rotation thereof in the said curved trajectory parts. In particular, at least a pitching (i.e. rotation about the axial or width direction) and a yawing (i.e. rotation about the radial or height direction) of the transverse segments and preferably also a rolling (i.e. rotation about the tangential or thickness direction) of the transverse segments relative to the ring stack is limited thereby. In WO2018/210456-A1 the transverse segments each include two protrusions (and corresponding cavities), one provided in each of its pillar parts.

Moreover during operation, in particular rotation of the drive belt in the transmission, the transverse segments thereof are intended to slide, i.e. slip relative to a radially innermost ring of its ring stack. Also the individual rings of the ring stack can also slip relative to one another in circumference direction. By such slip combined with a (normal) force between the ring stack and the transverse segments, as well as mutually between the individual rings of the ring stack, friction (power) losses occur internally in the drive belt and heat is generated. For minimizing such belt-internal friction losses, for cooling and for avoiding excessive wear due to such slip, lubricant is supplied to the drive belt during operation of the transmission. Some of this lubricant ends up between the ring stack and the transverse segments and between the rings of the ring stack themselves, lubricating the slipping contact there between. For promoting such ring stack lubrication, it is known to recess a part or parts of the front surface of the transverse segment adjacent to the bearing surface in thickness direction, in particular relative to the rocking edge. Each such relatively recessed surface part providing a channel between two successive and mutually contacting transverse segments in the drive belt, allowing lubricant to flow from radial inside the drive belt directly to the radial inside of the ring stack, in particular at the pulleys. This latter design feature of the known drive belt is particularly relevant for the said alternative basic design thereof, in which case ring stack is enclosed on all sides by the transverse segments.

Underlying the present invention is the ever-present desire to improve the operational performance of the drive belt design. In particular, in this respect, the present invention focusses on the friction contact between the pulleys and the drive belt. According to the present invention this friction contact can be improved upon, at least in the context of the preferred manufacturing process steps of (fine-)blanking the transverse segments from strip-shaped basic material and of quench hardening the blanked transverse segments. In particular, the circumference surface of the transverse segment that is cut in blanking is not oriented in parallel with the thickness direction of that transverse segment, at least not exactly. That is to say that, the transverse segment is not formed precisely rectangular in cross-section, but instead is somewhat tapered in its thickness direction and/or is somewhat curved in its width direction. Effectively, the width of the front surface of the transverse segment is slightly less than the width of the rear surface. As a result, the pulley contact surfaces on opposite sides of the transverse segment are mutually diverging in a direction away from the front surface of the transverse segment that is on the side of the blanking die and towards its rear surface that is on the side the blanking punch.

Although an angle between the pulley contact surfaces of the transverse segment due to the said diverging thereof is small, e.g. 2 degrees or less and typically around 1 degree, such divergence angle still appears to influence the wear of the transverse segment and/or the friction contact between the transverse segment and the pulleys. In particular it is considered that, by the mutually diverging pulley contact surfaces, such contact is disadvantageously concentrated at the rear of the transverse segment, rather than being more evenly spread across its thickness. Also the transverse segments may be clamped between the pulley discs in a disadvantageously slanted orientation, with one pulley contact surface thereof being aligned essentially in parallel with a respective pulley disc (i.e. the disc it is in contact with) and the other one pulley contact surface thereof being oriented relative to the other pulley disc at the said divergence angle.

Thus, according to the present invention, the performance of the drive belt in the transmission can be improved by reducing, preferably minimising the mutual divergence of the pulley contact surfaces of the transverse segments from the front towards rear thereof.

According to the present invention a novel process step of reducing the said divergence angle between the pulley contact surfaces of the transverse segment is included in the overall manufacturing process thereof. In particular according to the present invention, such novel process step entails either: the grinding of the pulley surfaces contact surfaces of the transverse segment into essentially parallel surfaces; or the bending of the transverse segment as a whole, to mutually align the pulley surfaces contact surfaces thereof essentially in parallel.

The above observations and considerations underlying the present invention as well as the proposed solutions will now be explained in more detail with reference to the drawing figures, whereof:

- figure 1 is a simplified and schematic perspective view of a known transmission with two pulleys (illustrated in cross-section) and a drive belt consisting of a ring stack and a row of transverse segments mounted on the ring stack along the circumference thereof;

- figure 2 illustrates the known drive belt in a schematic cross-section and in two basic designs thereof;

- figures 3 and 4 illustrate the known process step of blanking the transverse segment in a schematic and simplified cross-section of a fine-blanking device;

- figure 5 provides two schematic cross-sections of a part of the known transverse segment, illustrating a limitation of the known manufacturing method process in relation to the parallelism of the cut surfaces thereof;

- figure 6 schematically illustrates a first novel process step according to the present invention of grinding the transverse segment after blanking; and

- figure 7 schematically illustrates a further novel process step according to the present invention of bending the transverse segment after blanking.

Figure 1 schematically shows, in a cross-section thereof, the central parts of a continuously variable transmission for use in a driveline of, for example, passenger motor vehicles. This transmission is well-known and comprises at least a first variable pulley 1, a second variable pulley 2 and a drive belt 3 fitted around these pulleys 1, 2. In the driveline, the first pulley 1 is coupled to and driven by a prime mover of the vehicle, such as an electric motor or a combustion engine, and the second pulley 2 is coupled to and drives a driven wheel of the vehicle, typically via a number of gears. The pulleys 1, 2 each typically comprise a first conical disc 5 that is fixed to a respective pulley shaft 6, 7 and a second conical disc 4 that is axially displaceable relative to such respective pulley shaft 6, 7 and that is fixed thereto in rotational direction. As appears from figure 1, the trajectory of the drive belt 3 in the transmission includes two straight parts, where the drive belt 3 crosses over between the pulleys 1, 2 and two curved parts where the drive belt 3 is wrapped around the two pulleys 1, 2 while being clamped between the conical discs 4, 5 thereof.

The drive belt 3 is composed of a ring stack 11 and a plurality of transverse segments 10 that are mounted on the ring stack 11 along the circumference thereof in an, at least essentially, contiguous row. A thickness of the transverse segments 10 is small relative to a circumference length of the ring-stack 11, typically between 1.2 and 1.8 mm, such that several hundred transverse segments 10 are comprised in the said row thereof. However, for the sake of simplicity, only a few of the transverse segments 10 of the drive belt 3 are shown in figure 1. The ring stack 11 itself is composed of a number of flat, thin and flexible individual rings 12 (see figure 2) that are mutually nested with minimal tolerance, such that these rings 12 share the load when the drive belt 3 is operated in the transmission. Mostly between 6 and 12 rings 12 having a thickness of around 185 to 200 micron are applied in the ring stack 11.

In the drive belt 3, the transverse segments 10 are movable along the circumference of the ring stack 11, such that during operation of the transmission these can be driven by the first pulley 1 in the direction of rotation thereof by friction. These driven transverse segments 10 push preceding transverse segments 10 in the circumference direction of the ring stack 11 and, ultimately, rotationally drive the second pulley 2, again by friction. In order to generate such friction (force) between the transverse segments 10 and the pulleys 1, 2 the said pulley discs 4, 5 of each pulley 1, 2 are urged towards each other, whereby these clamp the transverse segments 10 between them in the respective curved trajectory part of the drive belt 3. To this end, electronically controllable and hydraulically acting movement means (not shown) that act on the moveable pulley disc 4 of each pulley 1, 2 are provided in the transmission. These movement means also control respective radial positions R of the drive belt 3 at the pulleys 1, 2 and, hence, the speed ratio that is provided by the transmission in the driveline between the pulley shafts 6, 7 thereof, as well as a tensioning of the ring stack 11.

In figure 2, two known basic designs of the drive belt 3 are schematically illustrated in a cross-section thereof facing in the circumference direction thereof.

On the left-side of figure 2 an embodiment of the drive belt 3 is illustrated, wherein the ring stack 11 is provided in two parts that are each accommodated in a respective axially oriented recess 13 of the transverse segment 10 that opens towards a respective, i.e. left and right, axial side thereof. These axial recesses 13 are defined on either side of a relatively narrow central or neck part 15 of the transverse segment 10, between a bottom or body part 14, located radially inward of the ring stack 11, and a top or head part 16 thereof, located radially outward of the ring stack 11.

On the right-side of figure 2 an embodiment of the drive belt 3 is illustrated incorporating a single ring-stack 11. In this case, the ring stack 11 is accommodated in a centrally located opening 17 of the transverse segment 10 that opens towards the radial outside of the drive belt 3. Such central opening 17 is defined between a base part 18 and two pillar parts 19 of the transverse segment 10 that respectively extend from either axial side of the base part 18 in radial outward direction. In such radial outward direction, the central opening 17 is partly closed-off by respective, axially extending hook parts 20 of the pillar parts 19. Although in figure 2 the hook parts 20 are of equal axial extent, these can also be of mutually different axial extent that are, moreover, mutually provided on opposite sides of the transverse segment 10 for successive transverse segments 10 in the drive belt 3, as taught by WO2018/210456-A1.

On either side thereof, either type of transverse segments 10 of both of the drive belts 3 are provided with contact faces 21 for arriving in friction contact with the pulley discs 4, 5. The contact faces 21 of each transverse segment 10 are mutually oriented at an angle f that closely matches an angle of a V-shaped groove defined by the pulleys 1, 2 between the conical discs 4, 5 thereof. The pulley contact faces 21 of the transverse segment 10 are typically either corrugated by a macroscopic profile or are provided with a rough surface structure, such that only the higher lying peaks of the corrugation or of the surface roughness arrive in contact with the pulleys 1, 2. This particular feature of the transverse segment design provides that the friction between the drive belt 3 and the pulleys 1, 2 is optimised by allowing cooling oil that is applied in the known transmission to be accommodated in the lower lying parts of the corrugation or of the surface roughness.

Abutting transverse segments 10 in the said row thereof in the drive belt 3, are able to tilt relative to one another, while remaining in mutual contact at and through an axially extending, convexly curved part 22 of a front surface 23 thereof that is denoted rocking edge 22 hereinafter. Above, i.e. radially outward of such rocking edge 22, the transverse segment 10 has an essentially constant thickness, whereas below, i.e. radially inward of such rocking edge 22, the transverse segment 10 is tapered, i.e. has a thickness that decreases in radially inward direction (whether gradually, stepwise or by a combination thereof), to allow for the afore-mentioned relative tilting without interference between the body or base parts 14; 18 of the abutting transverse segments 10.

In case of the transverse segment 10 with the central opening 17 depicted on the right side of figure 2, a recessed area 24 is provided in the front surface 2 of the transverse segment 10 adjoining the central opening 17 thereof and recessed in thickness direction relative to the rocking edge 22. The recessed area 24 provides a channel between the abutting transverse segments 10, allowing lubricant to flow from radially inside the drive belt 3 to the radial inside of the ring stack 11. Such lubricant is supplied to the transmission during operation, not only for cooling it, but also for lubricating the dynamic contact between the transverse segments 10 and the ring stack 11, as well as between the individual rings 12 of the ring stack 11.

The transverse segment 10 is typically cut out of plate- or strip-shaped basic material 50 in a blanking process by means of a blanking device 60. In figures 3 and 4, the blanking device 60 and the basic material 50 are schematically illustrated in a cross- section. In the blanking device 60 a blanking punch 30, an ejector 40, a guide plate 70 and a die 80 are applied. The guide plate 70 and the die 80 serve both to clamp the basic material 50 between them and to contain the blanking punch 30 and the ejector 40 in respective guiding spaces 71, 81 thereof.

The part 51 of the basic material 50 that is located between the blanking punch 30 and the ejector 40 is destined to become the transverse segment 10. During blanking the bottom working surface 31 of the blanking punch 30 and a top working surface 41 of the ejector 40 are pressed against the basic material 50, at mutually opposite sides thereof, and the blanking punch 30 and the ejector 40 are moved in unison completely through the basic material 50 in the general direction from the blanking punch 30 to the ejector 40. As a result, the transverse segment 10 is cut out of the basic material 50 along the edges of the die 80, as illustrated in figure 5. Accordingly, the said working surfaces 31, 41 have an outline that substantially corresponds to the outer contour of the transverse segment 10. Moreover, the front surface 23 of the transverse segment 10 including the rocking edge 22 is shaped by the working surface 41 of the ejector 40, whereas the working surface 31 of the blanking punch 30 engages the opposite, rear surface 25 of the transverse segment 10. This particular arrangement of the blanking punch 30 and of the ejector 40 may be reversed in principle. For facilitating the cutting, the edges of the die 80 are chamfered. However, in reality, the amount of chamfering is much less than what is shown in figures 3 and 4 for clarity. For example, typically, the depth of the chamfering amounts to approximately one tenth of the thickness of the basic material 50. The blanking punch 30 of the blanking device 60 is arranged to cut through the basic material 50 in a straight line, perpendicular to the top and bottom surfaces thereof that correspond to the rear surface 25 and the front surface 23 of the transverse segment 10 respectively. Nevertheless, the body or base parts 14; 18 of the transverse segment 10 are typically not shaped with exactly rectangular cross-section. As is schematically illustrated to a much exaggerated extent in figure 5 in two cross-sections A-A of the body or base part 14; 18 of the transverse segments 10 may have an (isosceles) trapezoidal shape (figure 5, cross-section I), an arc shape (figure 5, cross-section II) or a combination of both. In either case, the pulley contact surfaces 21 on opposite sides of the transverse segment 10 are mutually diverging in a direction away from its front surface 23 towards its rear surface 25, as seen in the plane of the said cross-section A-A. The resulting angle of divergence Q between the pulley contact surfaces 21 in its thickness direction is rather small, i.e. typically 2 degrees or less with an average of around 1 degree.

Such imperfections in the (cross-sectional) shape of the transverse segment 10 are believed to be caused by the high forces that are exerted on the basic material 50 in blanking. These blanking forces not only cause elastic deformations of the blanking tools 30, 40, 70, 80 and of the basic material 50; 51 during blanking, which lead to shape imperfections in the blanked transverse segment 10, but also introduce internal stresses therein. When the blanked transverse segment 10 is subsequently austenitized, as part of the said quench hardening thereof, these internal stresses can exceed the high temperature yield strength of the basic material 50; 51, causing not only stress relaxation, but also plastic deformation. Moreover, it is believed that the actual quenching of the transverse segment 10, i.e. the rapid cooling thereof, can cause internal stresses that exceed the yield strength of the basic material 50; 51 and that thus contribute to the said shape imperfections of the transverse segment 10.

Although the said shape imperfections of the transverse segment 10 after blanking and quench hardening are small, these still appear to impact the performance of the drive belt 3 in the transmission. In particular, the friction contact between the transmission pulleys 1, 2 and the drive belt 3 appears to be suboptimal as a result. The present invention therefore proposes to at least partly compensate for such shape imperfections. In particular according to the present invention a further process step in introduced in the manufacturing process of the transverse segments 10 aimed at setting the divergence angle Q between the pulley contact surfaces 21 in thickness direction at a desired value, preferably of zero.

In a first embodiment of the further process step according to the invention that is schematically illustrated in figure 6, the pulley contact surfaces 21 of each transverse segment 10 of the drive belt 3 are grinded to reduce the said divergence angle Q there between. In particular, material RM is removed from the sides of the body or base part 14; 18 by grinding, such that after grinding the pulley contact surfaces 21 are mutually in parallel, i.e. both perpendicular to the width direction of the transverse segment 10. It is noted that, generally speaking, grinding process technology is widely available in the art and, as such, can be easily adapted to the presently proposed, specific application thereof.

In case the transverse segment 10 is arc-shaped (figure 6, cross-section II), i.e. curved, it remains arc-shaped after grinding, i.e. after removing the material MR. This aspect of the grinding process step is not a disadvantage per se, if all transverse segments 10 of the drive belt 3 have a similar shape, i.e. are similarly curved width-wise.

Grinding has the added benefit that the width of the body or base parts 14; 18 of the transverse segment 10 can be set with high accuracy, by carefully controlling the amount of the removed material RM. Moreover, as is visible in figure 6, relatively sharp transitions can in this way be favourably obtained between the pulley contact surface 21 and the front and rear surfaces 23, 25 of the of the transverse segment 10. Both these latter two aspects of the grinding process step are considered to further improve the said friction contact between the transmission pulleys 1, 2 and the drive belt 3. On the other hand, when grinding the pulley contact surfaces 21 also the said corrugation or roughness profile thereof is removed to a certain extent. This aspect of the grinding process can, however, be compensated in the design and/or the creation of the said corrugation or roughness profile, e.g. by increasing the initial height of the higher-lying peaks of the profile.

Further, according to the invention, the process step of grinding the transverse segment 10 is preferably carried out after the said process step of quenching hardening is completed, i.e. in the hardened condition thereof.

In a second embodiment of the further process step according to the invention that is schematically illustrated in figure 7, the body or base part 14; 18 of each transverse segment 10 of the drive belt 3 is (plastically) bend to reduce the said divergence angle Q between the pulley contact surfaces 21 thereof. In the illustrated example thereof, the bending is realized under the influence of a set of at least three forces F25, F23_L, F23_R on the body or base part 14; 18, whereof two forces F23_L, F23_R act at a respective, i.e. left and right side of the front surface 23 and whereof the third force F25 acts on the rear surface 25 essentially in the middle thereof, in the opposite direction of and balancing the said two forces F23_L, F23_R. In such bending process step, the transverse segment 10 is thus simultaneously stretched at (and near) its front surface 23 and compressed at (and near) its rear surface 25. As a result, the front surface 23 the body or base part 14; 18 is either bent into a convex shape (figure 7, cross-section I), or its pre-existing concave shape (figure 7, cross-section II) is at least partly removed, while the rear surface 25 thereof is either bent into a concave shape (figure 7, cross-section I) or its pre-existing convex shape (figure 7, cross-section II) is r at least partly removed.

Further according to the invention, the process step of bending the transverse segment 10, is preferably carried out before or at the latest during the austenitizing stage of the process step of quench hardening, to minimise the force required to bend the transverse segment 10 and to maximise the accuracy. In this case, the amount of bending applied to the transverse segment 10 preferably takes into account, i.e. pre-compensates for the said plastic deformation occurring in quenching and/or austenitizing.

It is noted that suitable implementations of the presently proposed bending process can be readily envisioned. For example, US2015/285336 specifically mentions a couple of bending techniques in relation to the transverse segment 10, albeit for realising another technical purpose. Alternatively, the known die/mould forming process can be applied. In any case, given the minimal amount of plastic bending deformation that is necessary to remove the small divergence angle Q, (elastic) spring-back of the transverse segment 10 needs to be taken into account. For example, for a width of the body or base part 14; 18 of the current transverse segment 10 in the range from 24 to 30 mm that is typically applied in practice, the typical divergence angle Q of 1 degree corresponds to a radius of curvature Rc of the body or base part 14; 18 in the range from 1,4 m to 1,7 m.

The present invention, in addition to the entirety of the preceding description and all details of the accompanying figures, also concerns and includes all the features of the appended set of claims. Bracketed references in the claims do not limit the scope thereof, but are merely provided as a non-binding example of a respective feature. The claimed features can be applied separately in a given product or a given process, as the case may be, but it is generally also possible to apply any combination of two or more of such features therein.

The invention is not limited to the embodiments and/or the examples that are explicitly mentioned herein, but also encompasses variants, modifications and practical applications thereof that lie within reach of the person skilled in the relevant art.

Claims

1. A method for manufacturing a transverse segment (10) from steel by means of, at least, a blanking process step and a subsequent quench-hardening process step, which transverse segment (10) is suitable for use in a drive belt (3) with a ring set (11) composed of a number of mutually nested rings (12) and with a row of such transverse segments (10) arranged on and movable along the ring set (11), each transverse segment (10) having a front surface (23) that arrives in contact with a rear surface (25) of a respectively adjacent transverse segment (10) in the drive belt (3) and which transverse segment (10) has a rocking edge (22) that extends in the width direction across the transverse segment (10) and that forms a transition in height direction between an upper part of the transverse segment (10) and a thinner, bottom part (14; 18) of the transverse segment (10), the bottom part (14; 18) of which transverse segment (10) is provided with a respective contact surface (21) on either side thereof in the width direction, destined for friction contact with the pulleys (1, 2) of a continuously variable transmission, characterized in that the method further includes a process step aimed at setting a divergence angle Q between the pulley contact surfaces (21) in the thickness direction of the transverse segment (10) at a desired value.

2. The method for manufacturing a transverse segment (10) according to claim 1, characterized in that, in the further process step, the said divergence angle Q is reduced.

3. The method for manufacturing a transverse segment (10) according to claim 1 or 2, characterized in that, in the further process step, the desired value for the said divergence angle Q is zero degrees.

4. The method for manufacturing a transverse segment (10) according to claim 1, 2 or 3, characterized in that, the further process step is a grinding process wherein at least one of the contact surfaces (21) of the transverse segment (10) is abrasively processed.

5. The method for manufacturing a transverse segment (10) according to claim 4, characterized in that, the further, abrasive process step is carried out after the quench- hardening process step.

6. The method for manufacturing a transverse segment (10) according to claim 1, 2 or 3, characterized in that, the further process step is a bending process wherein at least, but preferably exclusively, the bottom part (14; 18) of the transverse segment (10) is bent.

7. The method for manufacturing a transverse segment (10) according to claim 6, characterized in that, the further, bending process step is carried out before the quench- hardening process step or is carried out before a quenching of the transverse segment (1) as part of the quench-hardening process step .

8. The method for manufacturing a transverse segment (10) according to claim 6 or 7, characterized in that, in the further, bending process step and at least locally at the bottom part (14; 18) of the transverse segment (10), the front surface (23) of the transverse segment (10) either is bent more convex or is bent less concave, whilst the rear surface (25) thereof is simultaneously bent more concave or less convex respectively.

9. The method for manufacturing a transverse segment (10) according to claim 6, 7 or 8, characterized in that the transverse segment (10) has a nominal width in the range from 24 mm to 30 mm and has a nominal thickness in the range from 1.2 mm to 1.8 mm and in that in the further, bending process step, the bottom part (14; 18) of the transverse segment (10) is provided with a radius of curvature Rc in the range from 1.4 m to 1.7 m.