This disclosure relates to a method for manufacturing 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 drive belt is commonly known and is mainly applied running around and between the two transmission pulleys, which pulleys each define a V-groove of variable width wherein a respective circumference part of the drive belt is held.

A known type of drive belt comprises an essentially contiguous row of transverse segments that are mounted on and around the circumference of an endless carrier. Each such transverse segment defines a slot that is open towards the radial outside of the drive belt and that accommodates and confines a respective circumference section of the endless carrier, while allowing the transverse segments to move along the circumference thereof. The endless carrier is formed by a number of flat and thin rings that are mutually stacked in the radial direction. This particular type of drive belt, also denoted in the art as pushbelt, is known from the international patent application W02015/ 177372-A1 , for example.

In the above and the below description, the axial, radial and circumference directions are defined relative to the drive belt when placed in a circular posture. Furthermore, a thickness dimension of the transverse segments is defined in the circumference direction of the drive belt, a height dimension of the transverse segment is defined in the said radial direction and a width dimension of the transverse segment is defined in the said axial direction.

The known transverse segment comprises a base portion and two pillar portions that extend from the base portion at either axial side thereof in radial outward direction. The said slot accommodating the endless carrier is defined by and between the base portion and the two pillar portions. The base portion defines a carrying surface that forms that extends between the pillar portions forming the bottom of the slot, for supporting the endless carrier in radial outward direction.

In the row of transverse segments of the drive belt, at least a part of a front main body surface of the transverse segment abuts against at least a part of a rear main body surface of a respectively preceding transverse segment in the said row, whereas at least a part of the rear main body surface of the transverse segment abuts against at least a part of the front main body surface of a respectively succeeding transverse segment. At least one of these front and rear surfaces of the transverse segment, for example the front surface includes an axially extending, convexly curved surface part. This curved surface part divides the front surface into a radially outer and a radially inner surface parts that are oriented at an angle relative to one other. Abutting transverse segments in the drive belt are able to tilt relative to one another, while remaining in mutual contact at and through such curved surface part that is therefore denoted tilting edge hereinafter. The tilting edge allows the row of the transverse segments of the drive belt to follow a local curving of the ring stacks imposed by the transmission pulleys.

It is known in the art, for example form WO2013/097884 -Al , to provide an accurately defined contact between the transverse segments in the said trajectory part of the drive belt, to reduce vibrations during operation. In particular, in between the tilting edge and a radially outer section of each pillar portion, part of the front surface of the transverse segment are slightly recessed, i.e. are indented to a certain extent, at least relative to the tilting edge and the radially outer sections of the pillar portions. Thus, in the row of transverse segments of the drive belt, at least the tilting edge and the said radially outer sections of the pillar portions serve as areas of mutual contact between the adjacent transverse segments, whereas such mutual contact is avoided at the location of the said recessed parts of the front surfaces thereof. In other words, a thickness of the transverse segments is greater at the location of the said contact areas than at the location of the said relatively recessed parts of the front surface. In practice, however, such difference in thickness is small in absolute terms and will typically be in the order of magnitude of between a minimum of five to ten and a maximum of around one hundred micrometres.

Typically the transverse segments are manufactured, i.e. cut from a strip or plate of basic material in a known blanking process by means of a blanking device. The known blanking device comprises a die, a guide plate and a blanking punch, whereof the blanking punch is provided with an outline essentially corresponding to the outer contour of the transverse segment to be formed, while the die and guide plate are provided with internal cavities with a corresponding contour wherein the blanking punch is contained. In the known blanking process, the basic material is clamped by and between the guide plate and the die and the blanking punch is pressed through the basic material from the side of the guide plate to the side of the die, thus cutting the transverse segment out of the basic material. Furthermore, in the known blanking device and process, a counter punch or ejector is applied on the opposite side of the basic material relative to the blanking punch. This latter arrangement of the blanking device allows a front and/or a rear surfaces of the transverse segment to be shaped and calibrated during the blanking thereof, through the plastic deformation of the basic material by and between the end faces of the blanking punch and the ejector respectively. In particular, the said recessed parts of the front surface are created by corresponding, relatively raised parts of the end face of the ejector, which parts are pushed into and displace some volume of the basic material, thus locally reducing the thickness thereof. Naturally, the volume of basic material that is displaced to form the said recessed parts ends up elsewhere in the basic material. In particular, such volume of basic material is displaced towards the tilting edge and/or to the said radially outer sections of the pillar portions, i.e. towards the said contact areas .

According to the present disclosure, the known blanking process is difficult to control in mass-manufacture in terms of the resulting thickness of the transverse segments, in particular in terms of the said difference in thickness between the contact areas on and the relatively recessed parts of the front surface. For example, the volume of basic material that is displaced from the said the relatively recessed parts towards the contacts areas must be accurately defined to realise the (locally) intended thickness of the transverse segments. Regular rework of the end face of the ejector is therefore required to maintain the dimensional accuracy of the transverse segments produced. Also the force that needs to be exerted by the ejector for realizing the required displacement of basic material is considerable, but must still be very accurately controlled in and between each blanking stroke.

According to the present disclosure, the known blanking process can be improved at least in terms of a reduction of the required ejector force, but potentially also in terms of the dimensional accuracy of the transverse segments produced therein. In particular according to the present disclosure, each transverse segment is cut from the basic material in at least three steps by:

- first cutting the pillar portions of the transverse segment at least partly by punching a hole into the basic material to at least one side of both pillar portions at a location where these will be provided with the said relatively recessed part later by means of piercing punches;

- then forming the relatively recessed parts in the pillar portions by locally compressing the basic material between two shaping tools; and

- cutting the parts of or the complete contour of the transverse segment from the basic material by means of, at least, a blanking punch and an ejector.

Because, in accordance with the present disclosure, a hole is preformed to at least one side of each pillar portion, the said volume of basic material displaced to form the recessed part of each pillar portion can flow more easily, in particular can flow at least partly into the free space provided by the holes. Therefore, the said required ejector force is reduced and/or the dimensional accuracy of the transverse segments is improved.

Preferably in the second and third steps, the same tools are used, i.e. preferably one of the shaping tools of the second step also serves as the blanking punch in the third step and the other shaping tool of the second step also serves as the ejector in the third step. More in particular the said second and third steps are carried out in short succession or even, at least partly, simultaneously .

Preferably in the first step, a hole is punched into the basic material at both sides of the pillar portions. In this case four piercing punches are used and four holes are formed, to favourably allow the said volume of basic material to be displaced to both sides of the pillar portions.

The above-described method for manufacturing the transverse segment will now be explained in more detail by way of example on the basis of the description below with reference to the drawing, in which:

figure 1 is a simplified and schematic side elevation of a transmission with two pulleys and a drive belt;

- figure 2 illustrates the known drive belt with generally V-shaped transverse segments in a cross-section thereof facing in its circumference direction and also includes a separate side elevation of only the transverse segment thereof;

- figure 3 schematically shows a longitudinal cross-section of a blanking area of a blanking device with basic material being placed in there;

- figure 4 schematically illustrates the basic process of blanking the transverse segment with the blanking device of figure 3; and figures 5 and 6 schematically illustrate a novel method of manufacturing the transverse segment in three steps.

Figure 1 schematically shows, in a side elevation, the central parts of a continuously variable transmission 100 for use in a driveline of, for example, passenger motor vehicles. This transmission 100 is well-known per se and comprises at least a first variable pulley 101 and a second variable pulley 102. In the driveline, the first pulley 101 is coupled to and driven by a motor, i.e. engine and the second pulley 102 is typically coupled to driven wheels of the motor vehicle via a number of gears.

Both transmission pulleys 101, 102 comprise a first conical pulley sheave that is fixed to a pulley shaft 103, 104 of the respective pulley 101, 102 and a second conical pulley sheave that is axially displaceable relative to the respective pulley shaft 103, 104 and that is fixed thereto only in rotational direction. A drive belt 99 of the transmission is wrapped around the pulleys 101, 102, while being accommodated between the pulley sheaves thereof. As appears from figure 1, the trajectory of the drive belt 99 in the transmission 100 includes two straight sections ST and two curved sections CT where the drive belt 99 is curved around a respective one of the two transmission pulleys 101, 102.

During operation of the transmission, the drive belt 99 is pinched by and between the pulley sheaves of both pulleys 101, 102 and thus provides a rotational connection there between by means of friction. To this end, electronically controllable and typically hydraulically acting movement means working on the respective moveable pulley sheave of each pulley 101, 102 are provided in the transmission 100 (not shown) . In addition to exerting a pinching force on the drive belt 99, these movement means also control respective radial positions Rl and R2 of the drive belt 99 at the pulleys 101, 102 and, hence, the speed ratio that is provided by the transmission 100 between the pulley shafts 103, 104 thereof.

The known drive belt 99 is composed of an endless carrier 8 and a plurality of transverse segments 1 that are mounted on the endless carrier 8 along the circumference thereof in an, at least essentially, contiguous row. In the drive belt 99 the transverse segments 1 are movable along the circumference of the endless carrier 8, which endless carrier 8 is typically composed of a number of flexible metal bands, i.e. tin and flat metal rings, that are stacked one around one another, i.e. that are mutually nested.

In figure 2 the known drive belt 99 is illustrated in more detail. On the right side of figure 2 the drive belt 99 is shown in a cross-section facing in the belt' s circumference direction and on the left side of figure 2 a cross-section of only the transverse segment 1 is shown.

The known transverse segment 1 comprises a base portion 10 and two pillar portions 11, whereof the base portion 10 extends mainly in the axial direction of the drive belt 99 and whereof the pillar portions 11 extend mainly in the radial direction of the drive belt 99, each from a respective axial side of the base portion 10. In its thickness direction, the transverse segment 1 extends between a rear surface 2 and a front surface 3 thereof, both of which are oriented, at least generally, in the circumference direction of the drive belt 99. Between the pillar portions 11 and the base portion 10 thereof, the transverse segment defines a slot 5 for accommodating a circumference section of the endless carrier 8.

In order to prevent that the transverse segments 1 of the known drive belt 99 can separate from the endless carrier 8 thereof, in particular in a straight section ST thereof, at least one pillar portion 11 of each transverse segments 1 is provided with a hook part 13 that in axial direction extends over a part of the slot 5. Thus in the drive belt 99, the endless carrier 8 is contained in radial direction in the central slots 5 of the transverse segments 1 by the hook parts 13 thereof. In each pillar portion 11 of the transverse segment 1, a protuberance or stud 6 is provided that protrudes from the front surface 3 in, essentially, the said circumference direction. In the drive belt 99, the stud 6 is inserted in a depression or pocket 7 provided in the opposite, i.e. rear surface 2 of an adjacent transverse segment 1 to limit a relative movement between the adjacent transverse segments 1, at least to an extent determined by a clearance between the outer circumference of the studs 6 relative to the inner circumference of the pockets 7.

On the axial sides thereof, the transverse segment 1 is provided with contact surfaces 12 for contacting (the pulley sheaves of) the transmission pulleys 101, 102. These contact surfaces 12 are mutually oriented at an angle that closely matches an angle that is present between the conical pulley sheaves of the transmission pulleys 101, 102.

The transverse segment 1 is provided with a so-called tilting edge 4 in its front surface 3. This tilting edge 4 represents an axially extending transition between a radially outer section of the transverse segment 1 of essentially constant thickness and a radially inner section thereof that is tapered in radial inward direction. Typically, the tilting edge 4 is smoothly, convexly curved .

A part 14 of the front surface 3 of the transverse segment 1 at each pillar portion 11 thereof is recessed relative to the tilting edge 4 and a radially outer section 15 of the respective pillar portion 11, as schematically indicated in figure 2 by an exaggerated amount. Thus, in the row of transverse segments 1 in the straight section ST of the drive belt 99, at least the tilting edge 4 and the said radially outer sections 15 of the pillar portions 11 serve as areas of mutual contact between the adjacent transverse segments 1, whereas such mutual contact is avoided at the location of the said recessed parts 14 of the front surfaces 3 thereof. When these adjacent transverse segments 1 are tilted relative to one another in the curved section CT of the drive belt 99, they (can) remain in contact at the tilting edge 4.

The transverse segment 1 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 1. Accordingly, the blanking punch 30 and the ejector 40 have an outline that substantially corresponds to the outer contour of the transverse segment 1.

During blanking a bottom end face, i.e. working surface 31 of the blanking punch 30 and a top end face, i.e. 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 1 is cut out of the basic material 50 along the edges of the die 80, as illustrated in figure 4. Also during blanking the front surface 3 of the transverse segment 1, including the tilting edge 4 and the studs 6 thereof, is pressure shaped by the working surface 41 of the ejector 40 and the back surface 2 of the transverse segment 1, including the pockets 7 therein, is pressure shaped by the working surface 31 of the blanking punch 30. In particular for forming the pockets 7, the working surface 31 of the blanking punch 30 is provided with protrusions (not shown) .

According to the present disclosure and as illustrated in figures 5 and 6, the cutting of the transverse segment 1 from basic material 50 is carried out in three steps. In a first step of such novel manufacturing method, illustrated in figure 5, four holes 53 are punched into the basic material 50 by means of four piercing punches 90, whereof a part of the circumference surfaces define at least a part of a respective one of the two side faces of the two respective pillar portions 11 of the transverse segment 1 that is still to be cut from the basic material 50 in this first step. In figure 5 the material removed 52 from the basic material 50 by the piercing punches 90 and the holes 53 thus formed are indicated by solid lines, whereas the remainder of the contour of the -still to be cut- transverse segment 1 is indicated by the dashed lines. The holes 53 are located in line with the -still to be formed- recessed parts 14 of the front surfaces 3 of the transverse segment 1, in particular of the pillar portions 11 thereof.

The same section of the basic material 50 is thereafter subjected to second and third steps of the novel manufacturing method that are illustrated in figure 6. In the second step, two parts 54 of the basic material 50 located in between the preformed holes 53 are compressed and plastically deformed between two shaping tools, i.e. stamps 100 (whereof only one is visible in the illustration of figure 5) to form the said recessed parts 14 of the transverse segment 1. As a result of such compression some of the basic material 50 that is compressed between the two stamps 100 flows towards and into the preformed holes 53. Finally in the third step the remainder of the contour of the transverse segment 1 is cut out of the basic material 50 in the above-described conventional blanking process, preferably using the said stamps 100 of the second process step also in this third process step as, respectively, the cutter 30 and the ejector 40 of the blanking process .

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

The invention (s) represented by the present disclosure is (are) not limited to the embodiments and/or the examples that are explicitly mentioned herein, but also encompasses amendments, modifications and practical applications thereof, in particular those that lie within reach of the person skilled in the relevant art .