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Title:
PROCESS FOR FORMING A RING, FORMING TOOL AND FORMING MACHINE FOR USE IN SUCH PROCESS AS WELL AS PUSH BELT PROVIDED WITH SUCH A RING
Document Type and Number:
WIPO Patent Application WO/2006/004391
Kind Code:
A1
Abstract:
Process for forming a ring (10), which in final form, is to be used in a push belt provided with an endless tensile means, which is composed of a number of such rings (10), and a plurality of transverse elements carried by the endless tensile means, in which process the ring (10) is separated from a sheet metal tube (1) that is clamped and rotated within a turning machine (40), and in which process a lateral side face (11) of such ring (10) is subsequently shaped. In which process in a first step (step I) a forming tool (20) of the turning machine (40) is urged in radial direction relative to the tube (1), whereby locally tube material (5) is cut up and the ring (10) is separated, whereto the forming tool (20) is provided with a first cutting edge (30), and in which process in a second process step (step II) the forming tool (20) is urged in axial direction relative to the ring (10), whereby a lateral side face (11) of the ring (10) is shaped, whereto the forming tool (20) is provided with a further cutting edge (31).

Inventors:
CARRIO GAELLE ANNICK (FR)
HAMANN ANDREAS JOSEPH (NL)
Application Number:
PCT/NL2004/000461
Publication Date:
January 12, 2006
Filing Date:
June 30, 2004
Export Citation:
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Assignee:
BOSCH GMBH ROBERT (DE)
CARRIO GAELLE ANNICK (FR)
HAMANN ANDREAS JOSEPH (NL)
International Classes:
B23B5/16; B23B27/04; B23B27/06; B23B31/40; B23Q39/04; (IPC1-7): B23B27/04; B23B1/00; B23Q39/04
Foreign References:
US3563119A1971-02-16
US4698050A1987-10-06
GB2176140A1986-12-17
DE19844858C11999-09-16
EP1055738A22000-11-29
US5471900A1995-12-05
GB828596A1960-02-17
EP0425994A21991-05-08
EP0888840A11999-01-07
DE19526900A11997-01-23
GB1576284A1980-10-08
US2984493A1961-05-16
Attorney, Agent or Firm:
Plevier, Gabriƫl Anton Johan Maria (Postbus 500, AM Tilburg, NL)
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Claims:
CLAIMS
1. Process for forming a ring (10), which in final form is to be used in a push belt provided with an endless tensile means that is composed of a number of such rings (10) and a plurality of transverse elements carried by the endless tensile means, in which process the ring (10) is separated from a sheet metal tube (1) that is clamped and rotated within a turning machine (40), and in which process a lateral side face (11) of such ring (10) is subsequently shaped, characterised in that in a first process step (step I) a forming tool (20) of the turning machine (40) is urged in radial direction relative to the tube (1), whereby locally tube material (5) is cut up and the ring (10) is separated, whereto the forming tool (20) is provided with a first cutting edge (30), and in that in a second process step (step II) the forming tool (20) is urged in axial direction relative to the ring (10), whereby a lateral side face (11) of the ring (10) is shaped, whereto the forming tool (20) is provided with a further cutting edge (31).
2. Ring forming process according to claim 1 characterised in that the forming tool (20) is provided with two further cutting edges (31), one on each lateral side of the tool (20), whereby in the second process step (step II) the tool (20) is subsequently urged to the left and right axial directions, whereby the ring (10) and the tube (1) are subsequently engaged by the tool (20) and whereby both lateral side faces (11) that were formed in the first process step (step I) on each side of the tool (20) are shaped.
3. Ring forming process according to claim 1 or 2, characterised in that the shape of the further cutting edge (31) or edges (31 ) at least corresponds to the desired, at least commercially applied shape of the lateral side face (11) of the ring (10) applied in the push belt.
4. Ring forming process according to any one of the preceding claims, characterised in that during both the process steps (step I; step II) the tube (1) and/or the ring (10) are rotated over a relatively large number of revolutions.
5. Forming tool (20) for replaceable use in a turning machine (40) provided with a first cutting edge (30) located at a free end of a base part (21) of said tool (20) and with at least one further cutting edge (31) located at a lateral side of an intermediate part (23) of said tool (20), which intermediate part (23) preferably adjoins the said base part (21).
6. Forming tool (20) according to the preceding claim, characterised in that, said further cutting edge (31) is defined by a laterally opening slot (24) in the intermediate part (23) of said tool (20).
7. Forming tool (20) according to the preceding claim, characterised in that, said laterally opening slot (24) widens both in lateral and in longitudinal direction away from the further cutting edge (31 ) defined thereby.
8. Forming tool (20) according to any one of the claims 5, 6 or 7, characterised in that, the further cutting edge (31) is at least partly shaped parabolic.
9. Turning machine (40) provided with means for clamping and rotating a sheet metal tube (1) and with a holder (46) onto which one or more forming tools (20) in accordance with any one of the claims 58 are mounted, which holder (46) is provided movable in the turning machine (40) both in radial and in axial direction with respect to the tube (1).
10. Turning machine according to the preceding claim provided with a support (43) for supporting and clamping the tube (1 ) on the inside, which support (43) is provided with one or more circumferential grooves (44), each for allowing a respective forming tool (20) of the turning machine (40) to penetrate through the tube (1).
11. Manufacturing process for a push belt that is provided with an endless tensile means that is composed of a number of rings (10) and a plurality of transverse elements carried by the endless tensile means, in which process a forming tool (20) and/or a turning machine (40) according to one of the claims 510 is applied.
12. Push belt provided with an endless tensile means that is composed of a number of rings (10) and a plurality of transverse elements carried by the endless tensile means, which push belt comprises a ring (10) originating from the process according to any one of the claims 14 and 11.
Description:
PROCESS FOR FORMING A RING, FORMING TOOL AND FORMING MACHINE FOR USE IN SUCH PROCESS AS WELL AS PUSH BELT PROVIDED WITH A SUCH A RING

The present invention relates to a push belt for a continuously variable transmission and to a method of manufacturing a ring for such a push belt. In final form -where these are denoted "bands"- and in nested combination with one another such rings constitute an endless tensile means for a push belt. The rings are in the known manufacturing process for push belts obtained by slitting, i.e. cutting them from a tube, normally prepared from plate shaped metal material, usually maraging steel. This and subsequent process steps for preparing a band to be used in the tensile means of a push belt are generally discussed in, for instance, the European patent publication EP-A-1055738. After that a ring has been slit, it is usually (stone) tumbled together with many other rings for the removal of burrs created in the slitting process, as well as for the shaping the lateral side faces of the rings by rounding off at least the edges thereof. The above-described known process provided satisfactory results for many years already. However, at the same time it has the principle disadvantage in that the process of tumbling is not a well-defined one. Moreover, during the batch-wise tumbling process step the ring material is not yet hardened and the rings may damage one another. Further, during operation the tumbling machine becomes contaminated with foreign particles such as burrs removed from the rings, which may also damage a ring. For the above reason it is an object of the invention to provide for an alternative, more defined and more favourable process for preparing these known rings. According to the invention, such aim can be realised by applying the process according to claim 1. With the process according to the invention, a ring is first separated by forcing a cutting tool part of the forming tool through the wall of the tube whilst it is turning and, subsequently, the lateral side faces of the separated ring are treated by bringing them into abrasive contact with a shaping tool part of the forming tool such that burrs are removed and, moreover, the side face are provided with a defined shape. Advantageously, the ring is cut-off and its lateral side faces are treated, i.e. deburred and shaped, in the same position and in a single machine. An additional advantage gained with the invention is that the cutting edge of the cutting tool parts and that of the shaping tool part are favourably integrated into one combined forming tool and, moreover, that a single machine may be applied, as compared to the known combination of the slitting and tumbling machines and tools. Also, in the proposed method neither the problem of ring to ring contact nor that of contamination will occur, because the tumbling process may be completely obviated. The invention will now by way of example be further elucidated along a drawing, in which: Figure 1 schematically shows the existing process for slitting rings from a tube; Figure 2 is a photographic representation of a cross section of a ring part typically obtained by the known slitting process; Figure 3 schematically shows the existing process for tumbling rings; Figure 4 is a photographic representation of a cross section of a ring part typically obtained by the known slitting and tumbling processes; Figure 5 is a principle scheme illustrating the improvement effect in manufacturing of rings according to the invention; Figure 6 illustrates a forming tool proposed by the invention, implicitly indicating the process proposed by the present invention; Figure 7 schematically illustrates such forming tool applied in a suitable manufacturing machine. A push belt, generally known per se, comprises an endless tensile means and a plurality of transverse elements, which are accommodated freely slidable along the longitudinal circumference of the tensile means. The endless tensile means consists of one or more sets of mutually nested metal bands that are prepared from relatively thin -i.e. typically about 0.2 mm thick- metal rings 10 by means of a/o rolling, annealing, calibrating, hardening and nitriding processes. The rings 10 themselves are often obtained by cutting, i.e. slitting from a tube-like base part 1 , or tube 1 for short that is usually made of sheet metal material -i.e. typically about 0.4 mm thick-, which process step is schematically represented by figure 1 along a cross section square to the axial direction of the tube 1. In figure 1 a tube 1 is represented along which the circles 2 indicate radial positions of an essentially cylindrical and rotatable cutting tool 2 relative to the tube 1 during the cutting process. However, the cutting tool 2 in fact has a fixed radial position, whereas the tube 1 is rotated with respect thereto. Inside the tube 1 a counter tool 3 provides a support for the tube 1 when the cutting tool 2 moves radially inward during the cutting process. In this cutting process the tube is mounted on a rotatable holder, which is not represented. During the cutting, both the tube and the two knifes rotate, however only one of these elements is rotatably driven. In the figure 1 the arrows provide the relative rotational movement of the components. Some relative radial positions of the cutting tool 2, which as mentioned in reality has a fixed tangential position at the circumference of the tube 1 , are represented by the Roman numbers, which positions illustrate several stages of the slitting process. In radial position I the cutting tool 2 is positioned in contact with the outer surface of the tube 1. In the radial position HA, the cutting tool 2 is in a initial cutting phase, at which the tube 1 , in this example, is rotated over about 90 degrees and at which the cutting tool 2 has cut up to about two thirds of the wall thickness of the tube 1 in radial direction. In the radial position MB, the cutting tool 2 has cut over the entire wall thickness up to the inner surface of the tube 1 , at which it is rotated over about one- half of its circumference. The initial cutting phase is thereby completed. In this initial cutting phase the cutting tool 2 causes a spiral-like cutting line S in the material of the tube 1 , of which line S two examples are provided in figure 1. After the initial cutting phase, a ring 10 is fully separated from the tube 1 in a final cutting phase, wherein the cutting tool 2 is taken through the material of the tube 1 over the full circumference thereof, i.e. one full rotation of the tube 1 , whilst it is in the radial position III in which it partly projects beyond the inner surface of the tube 1. Figure 2 is a photographic representation of a typical cross section of a part of a ring 10 including a lateral side face 11 thereof, which ring 10 is obtained along the above-described cutting process and includes a clearly recognisable burr 4 that is created as a consequence of such known process. For removing such burr 4, the ring ,10 is subsequently treated in a tumbling process also known per se, which process is schematically illustrated by figure 3 in a figurative cross-section of a tumbling machine. During tumbling a number of rings 10 are put into a vessel 50 with more or less cone-shaped tumbling stones 51, which vessel is made to shake w.r.t. the floor 52 as indicated by the arrows in figure 3. By the stones 51 impacting the rings 10, not only the burr 4 is removed but also the lateral side faces 11 of the ring 10 are shaped by a rounding-off of the edges thereof to a certain extent, which a/o depends on the intensity of the tumbling process. Figure 4 is a photographic representation of a typical cross section of a part of a ring 10 including a lateral side face 11 thereof, which ring 10 is obtained along the above-described cutting and tumbling processes. The general shape of the lateral side faces 11 after tumbling is essentially parabolic. Figure 5 is a principle scheme illustrating the process flow for the separating of a ring 10 from a tube 1 of base material and subsequently shaping the lateral side faces 11 thereof to form a "shaped ring" in accordance with the invention and in comparison with the above process steps. It illustrates that the novel manufacturing process denoted as "ring forming process" is significantly simplified in that only one treatment instead of two is required. A major advantage of the novel process is that the lesser-defined process of random tumbling is replace by a more defined one. Figure 6 by way of a front elevation of a combined cutting and forming tool 20, denoted forming tool 20 for short, illustrates the principle of the novel manner of separating a ring 10 from a tube 1. The front elevation shows a lower most cutting edge 30 of a base part 21 of the tool 20, which is preferably shaped very slightly concave. This base part 21 serves as the cutting tool part 21 , which during use in a turning machine -depicted in figure 7- is moved in radial direction M through the material of the tube 1 to separate a ring 10 therefrom, as illustrated by step I in figure 6. The moving direction M extends parallel to a central axis A of the tool 20. The width of the cutting edge 30 is preferably as small as possible without compromising the strength of the tool 20, because at separating the ring 1 from the tube 1 the material 5 below the tool 20 is cut up by the cutting edge 30. A value of 1 to 2 mm for said width was found to be sufficient, which compares to a width of the rings 1 that is typically one order of magnitude larger. At its lateral ends, the base part 21 is provided with side walls 22, extending essentially straight, and square to the cutting edge 30, i.e. parallel to the central axis A. The front elevation further shows an intermediate 23 part of the tool 20. This intermediate part 23 serves as the shaping tool part 23, which during use in a turning machine is moved in axial direction X towards one of the lateral side faces 11 of the ring 10 and/or of the tube 1 until it engages the material thereof, thereby machining and shaping it towards a desired shape, as illustrated by step Il in figure 6. To this end, the intermediate part 23 is provided with two laterally opening slots 24. The shape of the slots 24 as seen in the front elevation determines the shape that will be provided to the lateral side faces 11 as a result of machining during which the ring 10 or tube is rotated, whereby the front edge 31 of each slot 24 sets forth a further cutting edge 31. In this manner, any burr on or irregularity of the lateral side faces 11 of a ring 10 caused by the cutting tool part 21 in the separating process step is removed and at least the edges of the lateral side faces 11 are shaped by the shaping tool part 23. Preferably, as seen in the front elevation, the slot 24 is provided with generally converging, i.e. inwardly tapered shape that is smoothly rounded where its lower edge 25 and its upper edge 25 merge. An idea underlying the above described new forming tool 20, is that after a ring 10 has been cut-off, i.e. separated from a tube 1 , it is still present mounted in the machine and its lateral side faces 11 may in fact be machined right away so as to deburr and shape at least the edges thereof. Figure 7 illustrates the relevant parts of a typical kind of turning machine 40 used for moving and positioning the forming tool 20. In this machine 40, the tube 1 is clamped to a rotating head 41 of an industrial machine by means of a clamp 42 in a manner that is known per se. Preferably a support 43 is used at inserting the tube 1 , which support 43 rotates with the tube 1 and provides a clamping mechanism for clamping the rings 10 to be separated from the tube 1 , as well as, preferably, an axial end of the tube 1 from the inside. The support 43 is provided with one or more circumferential grooves 44, each for allowing a tool 20 to penetrate through the tube 1. A groove 44 is dimensioned somewhat wider than the forming tool 20, so as to allow the tool 20 to move axially for shaping the lateral side faces 11 once the ring 10 has been cut off. The turning machine 40 further comprises a pusher-element 45 for removing the ring once it is formed, i.e. after it has been separated from the tube 1 and its lateral side faces 11 have subsequently been shaped. The forming tool 20 is provided in a holder 46 of the machine 40 that is vertically downward movable, or put alternatively in radially inward direction with respect to the tube 1 , to engage the material of the tube 1 by the cutting edge 30 of its base part 21 and separate a ring 10 therefrom in the step I of the ring forming process according to the invention. In step Il of the holder 46 is moved downward even further so that the slots 24 of the forming tool 20 are positioned essentially in the same horizontal plane as a lateral side face 11 of the tube 1 or ring 10. Subsequently, the holder 46 is moved horizontally, i.e. axially with respect to the tube 1 or ring 10, so that the tool 20 engages the relevant side face 11 by the further cutting edge 31 of the relevant slot 24. As mentioned, during the two steps of the ring forming process both the tube 1 and any rings 10 separated therefrom are rotated. It may be evident, that the above provided novel process for forming and processing rings for the push belt has many advantages over the known process. It may be departed from a standardised turning machine and software, as well as the use of, a well defined process is set forth, which are maintenance friendly, clean, without ring to ring contacts, easy to operate and have low operating failure.