CN108266494B

CN108266494B - Method for producing a transverse segment of a drive belt for a continuously variable transmission and transverse segment produced

Info

Publication number: CN108266494B
Application number: CN201711476858.5A
Authority: CN
Inventors: G·G·H·龙佩恩
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-12-30
Filing date: 2017-12-29
Publication date: 2021-11-26
Anticipated expiration: 2037-12-29
Also published as: NL1042202B1; CN108266494A; JP2018111133A

Abstract

The invention relates to a method for manufacturing a transverse segment (10) for a drive belt, the transverse segment (10) having side faces (17), between which side faces (17) inclined edges (18) extend in a front main body surface (11) of the transverse segment (10). According to the invention, before the transverse section (10) is cut out of the base material (50), a hole (90) is punched into the base material (50) in alignment with the oblique edge (18) of the transverse section (10) intersecting the lateral face (17) of the transverse section (10).

Description

Method for producing a transverse segment of a drive belt for a continuously variable transmission and transverse segment produced

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 for receiving and restraining a respective circumferential section of the annular carrier, while enabling the transverse segment to move along the circumference 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 applications WO2015/063132-a1 and 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.

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 said row, 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 subsequent 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 oriented at an angle relative to each other. Adjoining transverse segments in the drive belt can tilt relative to one another while remaining in mutual contact at and by such curved surface portions, which are therefore denoted as tilting edges in the following. The oblique edges enable the row of transverse segments of the drive belt to follow the local bending of the ring stack exerted by the transmission pulley.

Usually, the transverse segments are manufactured, i.e. cut, from a strip 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. Usually, also 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 ejector presses against the base material, exerting a reaction force in the direction of the blanking punch. The latter arrangement of the blanking device enables this body surface of the transverse segment to be plastically formed by the compressive force exerted by the end face of the blanking punch and the end face of the ejector between the end faces of the blanking punch and the ejector. In particular, the inclined edge is defined in the front surface of the transverse section by an end face of the ejector.

A well-known feature of the known blanking process is that, at least in its aforementioned arrangement, a so-called roll-off occurs along the cutting edge of the transverse segment on the front surface, i.e. the ejector side of the transverse segment. In fact, the front surface of the transverse segment and the newly cut circumferential surface do not intersect in a sharp edge, but rather by a convexly curved transition surface between the front surface and the circumferential surface. Such a roll-off is also known in the art as a shrink or a recession. The adjoining transverse segments cannot contact each other in the region of the sagging at either axial side thereof. In fact, the oblique edge therefore does not extend over the entire local width of the transverse section, but ends at each side at a distance from the circumferential surface, which corresponds to the width of the roll-off. With such a reduced contact width between adjoining transverse segments, the contact stress and the associated wear disadvantageously increase. For at least the latter reason, it is preferable to minimize roll off.

Disclosure of Invention

According to the present disclosure, by cutting the transverse segment from the base material in at least two steps, the sagging can be advantageously reduced and the inclined edge extends further towards the circumferential surface of the transverse segment:

-first, partially forming the circumferential surface of the transverse segment to be formed by punching in a base material the side of the transverse segment in alignment with the oblique edge; and

after that, the rest of the profile of the transverse segment is blanked, i.e. cut, from the base material, while forming the oblique edges, in particular in a further conventional manner.

In fact, in the first step, a phenomenon is utilized that a high pressure is achieved in the base material during the blanking process by using a piercing punch having a small outer diameter. In particular, such high pressure results in a limited sagging compared to the sagging of known blanking processes. Thus, only a small sagging is locally formed by blanking the hole in line with the oblique edge, compared to the sagging formed in the second step when cutting the rest of the profile of the transverse segment. Preferably, two perforating punches are used in said first step, whereby holes are punched into the base material on both sides of the transverse section to be formed later in alignment with the oblique edges.

It is not important from which side the piercing punch penetrates the base material in terms of the (reduced) sagging that is produced. However, by bringing the piercing punch into contact with the basic material in the first step from the same side as the blanking punch used for forming the transverse section in the second step, it is found that in the second step less and/or smaller burrs are formed on the contour of the transverse section which are advantageous to some extent.

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:

FIG. 1 is a schematic side view of a continuously variable transmission having a drive belt;

FIG. 2 is a front view of a transverse segment of a drive belt for a continuously variable transmission;

FIG. 3 is a side view of the transverse segment shown in FIG. 2;

fig. 4 schematically shows a blanking area of the blanking device and a longitudinal section of a basic material placed in the blanking area;

fig. 5 schematically illustrates a blanking process;

fig. 6 is a schematic cross-sectional view of a portion of a known transverse segment, illustrating the limitations of the known blanking process in relation to the inclined edges of the transverse segment;

FIG. 7 illustrates a novel manufacturing method for cutting a transverse segment out of a base material in two steps;

FIG. 8 is a schematic cross-sectional view of a portion of a transverse segment illustrating the benefits of the novel manufacturing method of FIG. 7 with respect to the beveled edges of the transverse segment; and

fig. 9 provides an exemplary embodiment of a piercing punch for use in the novel method of manufacture of fig. 7.

Detailed Description

Fig. 1 schematically shows a continuously variable transmission, for example for use in a motor vehicle. The continuously variable transmission is substantially indicated with reference numeral 1.

The continuously variable transmission 1 comprises two pulleys 4, 5 arranged on separate pulley shafts 2, 3. The drive belt 6 is arranged in a closed loop around the pulleys 4, 5 and serves to transmit torque between the pulley shafts 2, 3. The pulleys 4, 5 are each provided with two pulley sheaves, wherein the drive belt 6 is positioned and clamped between said two pulley sheaves so that, with the aid of friction, a force can be transmitted between the pulleys 4, 5 and the drive belt 6.

The drive belt 6 comprises two endless carriers 7, said carriers 7 consisting of a bundle of a plurality of mutually nested, continuous belts or rings. The transverse segments 10 are arranged on the carrier 7 so as to form a substantially continuous column along the entire circumference of the carrier 7. The transverse segment 10 is arranged to be movable relative to the annular carrier 7, at least in the circumferential direction of the carrier 7. For the sake of simplicity, only some of these transverse segments 10 are shown in fig. 1.

Figures 2 and 3 show the transverse segment 10 of the known drive belt 6 in more detail. The front surface of the transverse segment 10 is substantially indicated with 11 and the rear surface of the transverse segment 10 is substantially indicated with 12.

In the vertical direction, the transverse section 10 comprises, in succession, a substantially trapezoidal shape of the bottom 13, a relatively narrow intermediate portion 14 and a substantially triangular shape of the top 15. In the drive belt 6, the bottom 13 is located at a radially inner circumferential side of the carrier 7, while the top 15 is located radially outwardly with respect to the carrier 7. Furthermore, in the drive belt 6, at least a part of the front surface 11 of a transverse segment 10 abuts against at least a part of the rear surface 12 of a subsequent transverse segment 10, while at least a part of the rear surface 12 of a transverse segment 10 abuts against at least a part of the front surface 11 of a preceding transverse segment 10.

The transverse segment 10 defines an opening 23 on both the left and right sides of the intermediate portion 14 of the transverse segment 10, said opening 23 being intended to receive a respective one of the ring-shaped carriers 7. These openings 23 are defined in the radially inward direction by respective bearing surfaces 16 supporting the annular carrier 7 in the radially outward direction. Furthermore, the bottom part 13 comprises two pulley sheave contact surfaces 17. When the transverse segment 10 moves over the pulleys 4, 5, contact between the transverse segment 10 and the contact surfaces of the pulley sheaves is established by said pulley sheave contact surfaces 17.

At the front surface 11 of the transverse section 10 a protrusion 21 is provided. In the example shown, the protrusion 21 is arranged in the top 15 and corresponds in position to a slightly larger hole provided in the rear surface 12. In fig. 3, the hole is depicted by means of a dashed line and is denoted by reference numeral 22. In the drive belt 6, the protrusions 21 of a transverse segment 10 are at least partially located within the holes 22 of an adjacent transverse segment 10. The protrusions 21 and the corresponding holes 22 serve to prevent or at least limit mutual displacement of adjacent transverse segments 10 in a plane perpendicular to the circumferential direction of the drive belt 6.

In addition, at the front surface 11 in the bottom 13 of the transverse section 10, a sloping edge 18 is defined. The inclined edge 18 is represented by a convexly curved region of the front surface 11, which separates two portions of said front surface 11 in the height direction, which are oriented at an angle with respect to each other. The beveled edge 18 is adjacent the bearing surface 16, but is still spaced below the bearing surface 16, i.e., radially inward relative to the bearing surface 16. An important function of the bevelled edges 18 is to provide a mutual pushing contact between adjacent transverse segments 10 when said transverse segments 10 are in a slightly rotated or bevelled position relative to each other at the pulleys 4, 5. To advantageously achieve a minimum contact stress in said push-contact between said transverse segments 10 and for stability of such contact, the inclined edge 18 preferably extends from the pulley sheave contact surface 17 to other locations, i.e. along the entire local width of the transverse segment 10.

The transverse segment 10 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. 4 and 5, 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. Both the guide plate 70 and the die 80 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 10. During blanking, the bottom surface or working surface 31 of the blanking punch 30 and the top surface or working surface 41 of the ejector 40 are pressed against the base material 50 at their opposite sides, and the blanking punch 30 and the ejector 40 move 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. 5, the transverse segment 10 is cut out from the base material 50 along the edge of the mold 80. The contour of said working

surfaces

31, 41 thus substantially corresponds to the outer contour of the transverse segment 10.

To facilitate cutting, the edges of the die 80 are chamfered. In practice, however, the amount of chamfering is much less than that shown in FIG. 5 for clarity. For example, the depth of the chamfer is typically about one-tenth the thickness of the base material 50.

During blanking, the front surface 11 of the transverse segment 10, including the inclined edge 18, is shaped by the working surface 41 of the ejector 40 and the rear surface 12 of the transverse segment 10 is shaped by the working surface 31 of the blanking punch. However, this particular arrangement of the blanking punch 30 and the ejector 40 may in principle be reversed.

A well-known feature of the above-described blanking process is that, at least in the above-described arrangement of the blanking process, a convexly curved transition surface 20 is formed between the front surface 11 of the transverse segment 10 and the cutting peripheral surface. This feature of the blanking process is also known in the art as a roll-off or a set-back. As schematically shown in fig. 6, in the transverse segment 10, a transition surface 20 is thus also present between the front surface 11 of the transverse segment and the pulley sheave contact surface 17. Fig. 6 is a partial section a-a of the bottom 13 of the transverse segment 10 depicted in fig. 2, intersecting its oblique edge 18. As can be seen in fig. 6, the inclined edge 18 does not extend completely to the axial side of the transverse segment 10 due to the presence of the countersink 20a, but ends at a distance D from the pulley sheave contact surface 17.

According to the present disclosure, the sagging may advantageously be locally reduced and the bevelled edge 18 may be extended further towards the pulley sheave contact surface 17 by introducing a pre-cutting step prior to blanking of the overall contour of the transverse segment 10. This novel manufacturing method is schematically illustrated in fig. 7 by looking down on the base material 50 and by its section B-B.

According to the present disclosure, the transverse segment 10 is cut from the base material 50 in at least two steps I, II. In a first step I, a hole 91 is punched in the base material 50 by means of a piercing punch 90. These holes 91 are located on either side of the transverse section 10 (indicated by a dashed line in fig. 7) to be formed later in alignment with the inclined edges 18 of the transverse section 10. The perforating punch 90 moves from a first main side 53 of the base material, preferably corresponding to the rear surface 12 of the transverse segment 10 to be formed, through the base material 50, to the opposite main side 52 of the base material. After said hole 91 is precut, i.e. in a second step II, the transverse section 10 is completely separated from the base material 50 by cutting the remaining contour of the transverse section by means of the blanking punch 30.

In fig. 8, the shape of the transverse segment 10 resulting from the above-described novel manufacturing method is schematically illustrated in the partial cross-section a-a of the bottom 13 of the transverse segment 10 depicted in fig. 2. As can be seen from fig. 8, the sagging 20b between the pulley sheave contact surface 17 and in particular the rear surface 12, which was formed in the first pre-cutting step I, is advantageously small. The inclined edge 18 thus extends almost to the axial side of the transverse segment 10, at least further in this direction than what is achieved with conventional manufacturing methods (fig. 6).

In fig. 9, said first step I of the above-described novel manufacturing method is shown in more detail, showing a possible profile and relative arrangement of the perforating punch 90. The piercing punch 90 is arranged to slightly overlap O with the pulley sheave contact surface 17 of the transverse segment 10 to be formed later in the second step II, i.e. with respect to the intended position of the pulley sheave contact surface 17. This feature allows for process variations, such as inaccurate positioning of the hole 91 formed in the base material 50 in the first step I with respect to the position of the blanking punch 30 in the second step II. According to the present disclosure, such overlap O is preferably between 0.025mm and 0.1mm, in particular at least 2 times the depth of the corrugated profile of the pulley sheave contact surface 17. In the final product transverse section 10, this overlap O forms an interruption of each pulley sheave contact surface 17 in line with the inclined edge 18 and in the form of a recess in the bottom 13 with respect to the plane defined by the respective pulley sheave contact surface 17.

Furthermore, as also shown in fig. 9, the portion of the piercing punch 90 that overlaps the transverse segment 10 to be formed later is preferably convexly curved. The radius of curvature R of this part of the piercing punch 90 is preferably small in order to maximize the extension of the inclined edge 18 as required, but at the same time should be large enough for the piercing punch 90, i.e. the punch hole 91, to cover a substantial part of the height of the inclined edge 18. According to the present disclosure, such a radius is preferably between 0.1mm and 0.5 mm.

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 for manufacturing a transverse segment (10) to be used in a drive belt (6) for a continuously variable transmission (1), which transverse segment (10) is provided with a slanted edge (18) in the form of a convexly curved region of a front surface (11) of the transverse segment (10), which slanted edge (18) extends in the width direction of the transverse segment (10) as far as a circumferential surface (16; 17) of the transverse segment and forms a transition edge between an upper portion (14; 15) of the transverse segment (10) having a substantially constant thickness and a conical lower portion (13) of the transverse segment, in which method the transverse segment (10) is cut from a base material (50), characterized in that the transverse segment (10) is cut from the base material (50) in two process steps, in a first process step at least one hole (91) being punched into the base material (50) by means of a punch (90), the perforating punch (90) has a convexly curved portion, wherein a portion of the outer circumference of the hole (91) formed by the convexly curved portion of the perforating punch (90) represents a portion of the circumferential surface (16; 17) of the transverse section (10) which is aligned with the inclined edge (18), wherein in a second processing step a portion or the entire contour of the transverse section (10) is cut out of the base material (50) by means of a blanking punch (30).

2. Method for manufacturing a transverse segment (10) according to claim 1, characterized in that in the first processing step two holes (91) are punched into the base material (50) by means of a piercing punch (90), a portion of the outer periphery of the holes (91) representing a portion of the circumferential surface (16; 17) of the transverse segment (10) located on either side of the inclined edge (18) and aligned with the inclined edge (18).

3. Method for manufacturing a transverse segment (10) according to claim 1 or 2, characterized in that the direction in which the piercing punch (90) moves relative to the base material (50) and through the base material (50) in the first processing step is the same as the direction in which the blanking punch (30) moves relative to the base material (50) and through the base material (50) in the second processing step.

4. Method for manufacturing a transverse segment (10) according to claim 1 or 2, characterized in that the perforating punch (90) is moved through the base material (50) from a back side (53) of the base material (50), the back side (53) of the base material (50) being positioned opposite to a side of the base material (50) representing the front surface (11) of the transverse segment (10) having the inclined edge (18).