CN110139997B

CN110139997B - Method for manufacturing a transverse segment of a drive belt for a continuously variable transmission

Info

Publication number: CN110139997B
Application number: CN201880005591.8A
Authority: CN
Inventors: R·范登赫费尔; G·G·H·龙佩恩
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-12-30
Filing date: 2018-01-02
Publication date: 2021-11-02
Anticipated expiration: 2038-01-02
Also published as: JP2020506058A; CN110139997A; WO2018122399A1; JP6976333B2; NL1042209B1

Abstract

The invention relates to a method for manufacturing a transverse segment (1) having a base part (10) and a pillar part (11) which defines a higher contact area (15) and a lower recessed surface part (14), the transverse segment (1) being intended as a part of a drive belt. According to the invention and before the transverse section (1) is cut out of the base material (50), a hole (53) is punched into the base material (50) at the side of the pillar part (11) at the location of its lower recessed surface portion (14). Thereafter, the lower concave surface portion (14) is pressed into the base material (50), and then the transverse segment (1) is completely cut from the base material (50).

Description

Method for manufacturing a transverse segment of a drive belt for a continuously variable transmission

Technical Field

The present disclosure relates to a method for manufacturing a transverse segment to be part of a drive belt of a continuously variable transmission having two pulleys and the drive belt. Such a drive belt is generally known and is mainly intended to run around and between two transmission pulleys, which pulleys each define a V-shaped groove of variable width in which a respective outer peripheral portion of the drive belt is retained.

Background

The drive belt of the known type comprises a substantially continuous row of transverse segments mounted on and around the circumference of the endless carrier. Each such transverse segment defines a slot which is open to the drive belt and which receives and bounds a respective circumferential section of the endless carrier, while enabling the transverse segment to move in the circumferential direction of the carrier. The annular carrier is formed by a plurality of flat and thin rings stacked on one another in the radial direction. A drive belt of this particular type, denoted in the art as a push belt, is known, for example, from international patent application WO2015/177372-a 1.

In the above and the following description, the axial direction, the radial direction, and the circumferential direction are defined with respect to the transmission belt when placed in a circular posture. Furthermore, the thickness dimension of the transverse segments is defined in the circumferential direction of the drive belt, the height dimension of the transverse segments is defined in the radial direction, and the width dimension of the transverse segments is defined in the axial direction.

The known transverse section comprises a base and two posts extending from the base in a radially outward direction at either axial side of the base. The slot for receiving the annular bearing member is defined between the base and the two posts by the base and the two posts. The base portion defines a bearing surface formed between the post portions and extending to form a base portion of the slot for supporting the annular bearing member in a radially outward direction.

In a row of transverse segments of the drive belt, at least a part of the front body surface of a transverse segment abuts against at least a part of the rear body surface of a respective preceding transverse segment in the row of transverse segments, and at least a part of the rear body surface of a transverse segment abuts against at least a part of the front body surface of a respective following transverse segment. At least one of these front and rear surfaces of the transverse section, for example the front surface, comprises an axially extending convexly curved surface portion. The curved surface portion divides the front surface into a radially outer surface portion and a radially inner surface portion, the radially outer surface portion and the radially inner surface portion being oriented at an angle relative to each other. Adjoining transverse segments in the drive belt can tilt relative to each other while at and by such curved surface portions being kept in mutual contact, thus denoted tilting edge in the following. The beveled edges enable the row of transverse sections of the drive belt to follow the local curvature imposed by the drive pulley in the circulating stack.

It is known in the art, for example from WO2013/097884-a1, to provide a well-defined contact between transverse segments in the track portion of the drive belt to reduce vibrations during operation. In particular, between the inclined edge and the radially outer section of each pillar, a portion of the front surface of the transverse section is slightly recessed, i.e. to some extent at least set back with respect to the inclined edge and the radially outer section of the pillar. Thus, in said row of transverse segments of the drive belt, at least the bevelled edge and said radially outer section of the pillar portion act as areas of mutual contact between adjacent transverse segments, while such mutual contact is avoided at the location of said recessed portions of the front surfaces of the transverse segments. In other words, the thickness of the lateral section at the location of said contact area is greater than the thickness at the location of this relatively concave portion of the front surface. In practice, however, the absolute value of this thickness difference is small and is generally of the order of between a minimum of 5 to 10 and a maximum of about 100 microns.

Usually, the transverse segments are manufactured, i.e. cut, from a strip or plate of base material by means of a blanking device in a known blanking process. The known blanking device comprises a die, a guide plate and a blanking punch, said blanking punch being provided with a profile substantially corresponding to the outer profile of the transverse segment to be formed, while the die and the guide plate are provided with an inner cavity with a corresponding profile accommodating the blanking punch. In the known blanking process, the base material is sandwiched between the guide plate and the die by the guide plate and the die, and the blanking punch is pressed from one side of the guide plate through the base material to one side of the die, thereby cutting out a transverse segment from the base material. Furthermore, in known blanking devices and processes, a counter-punch or ejector is applied on the opposite side of the base material with respect to the blanking punch. The latter arrangement of the blanking device enables the front and/or rear surface of the transverse segment to be shaped and calibrated during blanking thereof by plastic deformation of the basic material through and between the end faces of the blanking punch and the ejector, respectively. In particular, said recessed portions of the front surface are formed by respective opposite raised portions of the end surface of the ejector, which are pushed in and displace a volume of base material, thereby locally reducing its thickness. Of course, the volume of base material displaced to form the recessed portion is ultimately located elsewhere in the base material. In particular, the volume of base material is displaced towards the inclined edge and/or towards said radially outer section of the pillar portion, i.e. towards said contact area.

According to the invention, the known blanking process makes it difficult to control the final thickness of the transverse segments in mass production, in particular the difference in thickness between the contact area of the front surface and the relatively recessed portion. For example, the volume of base material displaced from the relatively recessed portion towards the contact region must be accurately defined to achieve a (locally) desired thickness of the lateral segment. Therefore, it is necessary to periodically rework the end faces of the ejectors to maintain the dimensional accuracy of the resulting transverse segments. Furthermore, the force required to be exerted by the ejector to achieve the required displacement of the base material is considerable, but still has to be controlled very accurately in and between each blanking stroke.

Disclosure of Invention

According to the present disclosure, the known blanking process may be improved at least in terms of reducing the required ejection force, but may also be improved in terms of dimensional accuracy of the transverse segments produced therein. In particular, according to the invention, each transverse segment is cut from the base material by at least three steps:

-first at least partially cutting the post sections of the transverse section by punching holes into the base material on at least one side of both post sections, after which said post sections will be provided with said relatively recessed portions at these locations by means of a perforating punch;

-then forming relatively recessed portions in the pillar portion by locally pressing the base material between two forming tools; and

-cutting a partial or complete profile of the transverse section from the base material by means of at least a blanking punch and an ejector.

Since, according to the present disclosure, a hole is formed in advance at least at one side of each pillar portion, the volume of base material displaced to form the recessed portion of the respective pillar portion can flow more easily, in particular can flow at least partially into the free space provided by the hole. Thus, the required ejection force is reduced and/or the dimensional accuracy of the transverse segments is improved.

Preferably, in the second and third steps the same tool is used, i.e. preferably one of the forming tools of the second step also serves as a blanking punch in the third step and the other forming tool of the second step also serves as an ejector in the third step. More particularly, said second and third steps are carried out consecutively or even at least partially simultaneously.

Preferably, in the first step, holes are punched into the base material on both sides of the pillar portion. In this case, four perforating punches are used and four holes are formed to advantageously displace the volume of base material to both sides of the post portion.

Drawings

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

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

figure 2 shows a known drive belt with a substantially V-shaped transverse section in a cross-sectional view of the drive belt facing in its circumferential direction, and also comprises a separate side view of only the transverse section of the drive belt;

fig. 3 schematically shows a blanking area of the blanking device and a longitudinal section of the base material placed in the blanking area;

fig. 4 schematically illustrates the basic procedure of blanking a transverse segment with the blanking device of fig. 3; and

figures 5 and 6 schematically show a novel method of manufacturing a transverse section in three steps.

Detailed Description

Fig. 1 schematically shows in side view the central components of a continuously variable transmission 100 for use in a driveline of, for example, a passenger car. The transmission 100 is known per se and comprises at least a variable first pulley 101 and a variable second pulley 102. In a drivetrain, a first pulley 101 is coupled to and driven by a motor, i.e. an engine, and a second pulley 102 is coupled to the driven wheels of the motor vehicle, typically via a plurality of gears.

Both

transmission pulleys

101, 102 comprise a first conical pulley sheave fixed to the

pulley shaft

103, 104 of the

respective pulley

101, 102 and a second conical pulley sheave axially displaceable relative to the

respective pulley shaft

103, 104 and fixed to the pulley shaft only in the direction of rotation. The transmission belt 99 of the transmission is wound around the

pulleys

101, 102 while being accommodated between the pulley sheaves of the pulleys. As can be seen from fig. 1, the trajectory of the drive belt 99 in the transmission 100 comprises two straight sections ST and two curved sections CT, wherein 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 pressed between the pulley sheaves of the two

pulleys

101, 102 by means of the pulley sheaves of the two

pulleys

101, 102, thereby providing a rotational connection between the pulley sheaves by means of friction. For this purpose, electronically controllable and usually hydraulically acting movement means which operate on corresponding movable pulley sheaves of the

respective pulleys

101, 102 are provided in the transmission 100 (not shown). In addition to exerting a pressing force on the drive belt 99, these movement means also control the respective radial positions R1 and R2 of the drive belt 99 at the

pulleys

101, 102 and thereby the rotational speed ratio between the

pulley shafts

103, 104 of the transmission, which is provided by the transmission 100.

The known drive belt 99 consists of an endless carrier 8 and a plurality of transverse segments 1, which transverse segments 1 are mounted on the endless carrier 8 in an at least substantially continuous row along the circumference of the endless carrier 8. In the drive belt 99, the transverse segments 1 are movable along the circumference of the endless carrier 8, the endless carrier 8 usually being composed of a plurality of flexible metal strips, i.e. thin and flat metal rings, which are stacked around one another, i.e. embedded in one another.

A known drive belt 99 is shown in more detail in figure 2. On the right side of fig. 2, the drive belt 99 is shown in a sectional view facing the circumferential direction of the belt, and on the left side of fig. 2, only a sectional view of the transverse segment 1 is shown.

The known transverse section 1 comprises a base part 10 and two column parts 11, wherein the base part 10 extends mainly in the axial direction of the drive belt 99 and the column parts 11 extend from respective axial sides of the base part 10, respectively, mainly in the radial direction of the drive belt 99. In its thickness direction, the transverse segment 1 extends between its rear surface 2 and its front surface 3, both surfaces being oriented at least substantially in the circumferential direction of the drive belt 99. Between the pillar portion 11 and the bottom portion 10 of the transverse segment, the transverse segment defines a groove 5, said groove 5 being intended to receive a circumferential section of the annular carrier 8.

In order to prevent the transverse segments 1 of the known drive belt 99 from being able to separate from the endless carrier 8 of the drive belt, in particular in the linear section ST of the drive belt, at least one pillar portion 11 of each transverse segment 1 is provided with a hook 13, which hook 13 extends in the axial direction over a portion of the groove 5. In the drive belt 99, the endless carrier 8 is thus accommodated in the central groove 5 of the transverse segment 1 in the radial direction by the hook 13 of the transverse segment.

In each pillar portion 11 of the transverse segment 1, a projection or peg 6 is provided which projects from the front surface 3 substantially in the circumferential direction. In the drive belt 99, the pegs 6 are inserted into recesses or notches 7 provided in the opposite surfaces of adjacent transverse segments 1, i.e. the rear surfaces 2, to limit the relative movement between the adjacent transverse segments 1, which is determined at least to some extent by the clearance between the outer circumferential surfaces of the pegs 6 relative to the inner circumferential surfaces of the notches 7.

The transverse section 1 is provided on its axial side 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 closely matching the angle existing between the conical pulley sheaves of the transmission pulleys 101, 102.

The transverse segment 1 is provided with a so-called bevel edge 4 in its front surface 3. The inclined edge 4 represents an axially extending transition between a radially outer section of the transverse segment 1, which has a substantially constant thickness, and a radially inner section of the transverse segment 1, which tapers in the radially inward direction. In general, the inclined edge 4 is smoothly convexly curved.

The portions 14 of the front surface 3 of the transverse segment 1 at its respective post 11 are recessed with respect to the inclined edge 4 and the radially outer section 15 of the respective post 11, as schematically shown in exaggerated quantities in fig. 2. Thus, in a row of transverse segments 1 in the straight section ST of the drive belt 99, at least the inclined edges 4 and said radially outer section 15 of the pillar portion 11 serve as areas of mutual contact between adjacent transverse segments 1. While such mutual contact is avoided at the location of said recessed portion 14 of the front surface 3 of the transverse section. When these adjacent transverse segments 1 are inclined with respect to each other in the curved section CT of the drive belt 99, these adjacent transverse segments (may) remain in contact at the inclined edges 4.

The transverse segment 1 is usually cut out of a plate-like or strip-like basic material 50 in a blanking process by means of a blanking device 60. In fig. 3 and 4, the blanking device 60 and the base material 50 are schematically shown in a cross-sectional view. In the blanking device 60, the blanking punch 30, the ejector 40, the guide plate 70, and the die 80 are used. The guide plate 70 and the die 80 both serve to clamp the base material 50 therebetween and to accommodate the blanking punch 30 and the ejector 40 in their

respective guide spaces

71, 81. The portion 51 of the basic material 50 between the blanking punch 30 and the ejector 40 will become the transverse segment 1. The contour of the blanking punch 30 and the ejector 40 therefore corresponds approximately to the outer contour of the transverse segment 1.

During blanking, the bottom end face of the blanking punch 30, i.e. the working surface 31, and the top end face of the ejector 40, i.e. the working surface 41, are pressed against the base material 50 at opposite sides of the base material 50, and the blanking punch 30 and the ejector 40 are moved in unison completely through the base material 50 in the general direction from the blanking punch 30 to the ejector 40. Thus, as shown in fig. 4, the transverse segment 1 is cut out from the base material 50 along the edge of the mould 80. In addition, during blanking, the front surface 3 of the transverse segment 1, including its inclined edges 4 and the peg 6, is pressed into shape by the working surface 41 of the ejector 40, and the rear surface 2 of the transverse segment 1, including the notch 7 therein, is pressed into shape by the working surface 31 of the blanking punch 30. In particular, for forming the recess 7, the working surface 31 of the blanking punch 30 is provided with a protrusion (not shown).

According to the present disclosure, cutting the transverse segment 1 from the base material 50 is performed in three steps, as shown in fig. 5 and 6. In a first step of this novel manufacturing method, as shown in fig. 5, four holes 53 are punched into the base material 50 by means of four perforating punches 90, a portion of the circumferential surface of said holes defining at least a portion of a respective one of the two side faces of two respective pillar portions 11 of the transverse segment 1 still to be cut from the base material 50 in this first step. In fig. 5, the material 52 removed from the base material 50 by the perforating punch 90 and the hole 53 formed thereby are indicated by solid lines, while the rest of the contour of the transverse segment 1 to be cut off is indicated by dashed lines. The hole 53 is positioned in alignment with the recessed portion 14 of the front surface 3 to be formed of the transverse segment 1, in particular the post portion 11 of the transverse segment 1.

The same section of base material 50 is then subjected to the second and third steps of the novel manufacturing method as shown in fig. 6. In a second step, the two portions 54 of the base material 50 located between the preformed holes 53 are pressed and plastically deformed between two forming tools, i.e. stamps 100 (only one of which is visible in the illustration of fig. 5), to form said recessed portions 14 of the transverse segment 1. Due to this pressing, a part of the pressed base material 50 between the two stamps 100 flows towards and into the preformed hole 53. Finally, in a third step, in which the rest of the contour of the transverse segment 1 is cut out of the basic material 50 in the above-described conventional blanking process, the stamp 100 of the second process step is preferably also used as the cutter 30 and the ejector 40, respectively, of the blanking process.

In addition to all of the details of the foregoing description and accompanying drawings, the present disclosure also relates to and includes all of the features of the appended claims. Parenthetical reference signs in the claims do not limit their scope, but are provided merely as non-limiting examples of the corresponding features. The claimed features may be applied individually, as the case may be, in a given product or a given process, but may also be applied simultaneously in any combination of two or more of such features.

The invention represented by this disclosure is not limited to the embodiments and/or examples explicitly mentioned herein, but also includes modifications, improvements and practical applications thereof, particularly those modifications, improvements and practical applications that occur to those skilled in the relevant art.

Claims

1. A method of manufacturing a transverse segment (1) suitable for use in a drive belt (99) for a continuously variable transmission, which transverse segment (1) comprises a base part (10) and two pillar parts (11), which pillar parts (11) extend from both sides of the base part (10) substantially parallel to each other, which pillar parts (11) are each provided with a respective recessed portion (14) of a front side surface (3) of the transverse segment (1), which recessed portions (14) are recessed with respect to a further portion (15) of the front side surface (3), in which method the transverse segment (1) is cut out of a basic material (50), characterized in that the transverse segment (1) is manufactured from the basic material (50) in at least three process steps, wherein in a first of these three process steps a hole (53) is punched in the basic material (50) on at least one side of the two pillar parts (11) respectively, a portion of the circumferential surface of the hole (53) defines at least a portion of a side face of the respective pillar portion (11) to be formed adjacent to the recessed portion (14) of the front side surface (3), wherein in a second of the three process steps the recessed portion (14) is pressed into the base material (50) by means of two stamps (100) located on opposite sides of the base material (50), wherein in a third of the three process steps a portion or a complete contour of the transverse section (1) comprising the two pillar portions (11) is blanked out of the base material (50) at least by means of the stamps (100) in the second process step which also serves as a blanking punch (30) and ejector (40) in the third process step, wherein the first process step is performed and completed before the second process step.

2. Method for producing a transverse segment (1) according to claim 1, characterized in that in the first process step a total of four holes (53) are punched in the base material (50) on both sides of the two pillar parts (11) to be formed in the third process step.

3. Method of manufacturing a transverse segment (1) according to claim 1 or 2, characterized in that the third process step is at least partially simultaneous with the second process step.

4. Method of manufacturing a transverse segment (1) according to claim 1 or 2, characterized in that in the second of the three process steps, the recessed portions (14) are pressed into the base material (50) by forcing the stamps (100) towards each other.