FR2763523A1 - METHOD FOR MANUFACTURING A FLAT OR TRONCONIC ANNULAR PART, AND PART OBTAINED BY THIS PROCESS - Google Patents

Abstract

The invention relates to a method of manufacturing a flat or frustoconical annular part comprising the following steps: - a section (2) of a metal wire (1) of predefined length is cut, - this section (2) is bent wire to form a torus (3), - the two ends (4, 5) of this torus are welded to obtain an annular blank (6), and - said blank (6) is compressed by means of a tool for forming said room.

Description

The invention relates to a method for manufacturing a flat annular part.

  or frustoconical such as for example a clutch rod, as well as a part obtained

by this process.

  A first known method of manufacturing such parts consists in: cutting a ring from a metal strip, - forming in the press an annular flat or frustoconical part, - degreasing the part obtained, subjecting the annular part to a tribofinishing,

- dry and oil the part.

  This known method has the disadvantage of generating significant

  scrap metal which considerably increases the manufacturing cost per piece.

  A second, slightly more economical method is known, which consists in: cutting a circular blank from a metal strip, - stamping the blank to obtain a hollow cylinder of revolution with closed bottom, - submitting the cylinder to a flow forming to obtain a blank cylindrical hollow whose thickness of the peripheral skirt is constant, - cut rings in the peripheral skirt, - form with the press from these rings flat or frustoconical parts, - degrease the parts obtained, pass the parts to tribofinishing ,

- dry and oil the parts.

  Although this second process makes it possible to reduce falls in a way

  important, these still represent around 40% of the amount of starting metal.

  These falls mainly come from the cutting of the blanks in the metal strip, as well as from the collar and the bottom of the hollow cylindrical blank which remain after the step.

cutting rings.

  In addition: - the two known methods have the drawback of requiring a

  significant number of manufacturing steps which contributes to increasing the cost.

  in the two aforementioned processes, the step of tribofinishing the rings is imperative in order to obtain the desired characteristics of the final parts, in particular by eliminating burrs. However, this operation produces metallic residues and requires the use of degreasers and abrasives, which are very polluting for the environment and require a specific and costly treatment for their landfill. Finally, this

  tribofinishing stage is noisy and requires special protection for personnel.

  The present invention aims to overcome these various drawbacks by proposing a method for making flat or frustoconical parts so

  more economical, while reducing the quantities of polluting residues.

  To this end, the subject of the invention is a method of manufacturing a flat or frustoconical annular part, characterized in that it comprises the following steps: - a section of a metal wire of predefined length is cut, - bend this section of wire to form a torus, * weld the two ends of this torus to obtain an annular blank, and

  - Said blank is compressed by means of a tool to form said part.

  The method according to the invention may also include one or more of the following characteristics: - A flat annular part is formed by compressing said blank (6)

  in a single press forming operation.

  - An annular frustoconical part is formed by compressing the part

  flat annular during an additional press forming operation.

  - A frustoconical annular part is formed in a single operation of

press forming.

  - We weld the two ends of the torus without adding metal.

  - The steps of cutting, bending and welding are carried out in one cycle

automatic on the same machine.

  - After having welded the two ends of the torus, at least the weld zone of the blank is subjected to a heat treatment to homogenize the

  mechanical characteristics in this area.

  - After obtaining the part, we successively submit it to a

  degreasing, drying and oiling.

  The invention also relates to a part produced by the method defined above and comprising a radial weld zone. Other characteristics and advantages of the invention will emerge from the

  following description, given by way of example without limitation with regard to the drawings

  attached, in which: FIG. 1 illustrates initial steps of the method of the invention, FIG. 2 is a schematic sectional view of a first tool for obtaining a flat annular part, in the disengaged position, FIG. 3 shows the tool of Figure 2 in the compression position, Figure 4 is a cross-sectional view of a flat annular part produced according to the method of the invention, Figure 5 is a schematic sectional view of a second tool for obtaining a frustoconical annular part, in the released position,

  Figure 6 shows the tool of Figure 5 in the compression position.

  Figure 7 is a cross-sectional view of a frustoconical annular part produced according to the method of the invention, Figure 8 is an enlarged view of a detail of the part shown in Figure 7, Figure 9 is a view similar to that of FIG. 8 of a variant of a frustoconical part produced according to the method of the invention and FIG. 10 is a view similar to that of FIG. 9 of a variant

  of a frustoconical part produced according to the method of the invention.

  In Figure 1 are shown the first steps of the method according to the invention. During a first step, a section 2 of a metal wire 1 of circular section unwound, for example from a coil of wire not shown, is cut.

preset length.

  The metal wire 1 is preferably made of mild steel but can be in all

  another metal suitable for the subsequent application envisaged.

  The diameter of the metal wire 1 is chosen as a function of the desired volume of the final part. In a specific case, for example, a metal wire 4.2 mm in diameter is used at the start. Of course, we can also use metal wires

of elliptical or other section.

  The length of the section 2 also depends on the desired dimensions of the final part. In the concrete case mentioned above, we chose a length of

section equal to 402.7mm.

  During the next step, the section 2 of wire is bent to form a torus 3. Then, the two ends 4 and 5 of this torus 3 are welded without adding metal to obtain

  an annular blank 6 with a radial weld zone 6A.

  Advantageously, the steps of cutting, bending and welding are carried out in an automatic cycle on a machine of known type sold by

  of specialized manufacturers and which it is useless to describe.

  If necessary, provision is made to subject at least the zone 6A of welding to a localized annealing in order to homogenize the mechanical characteristics in this zone. Such treatment may prove necessary to soften the structure of the metal in the case where

  a metal wire made of relatively hard steel is used at the start.

  Figure 2 shows in the disengaged position a first tool or a first press 7 of which only the upper 8 and lower 9 dies are shown. These matrices respectively define two planar, parallel annular surfaces 8A, 9A between

  which position the blank 6 centrally.

  The part is formed in a single operation as shown in FIG. 3, the blank 6 undergoing symmetrical deformation, with radial creep of the metal in equal proportions outward and inward. The compression exerted by the dies 8 and 9 is suitable for obtaining the dimensions and the desired mechanical properties of the part 13, in particular good flatness and satisfactory surface hardness. The flat annular part 13 obtained after this press forming step is shown in cross section in Figure 4. Its cross section has two long sides 14 and 15 substantially parallel to each other and two short sides 16 and 17 slightly rounded, this shape being obtained directly, without any additional machining. By way of example, the dimensions of a flat annular piece 13 obtained from a section of wire 4.2 mm in diameter and 402.7 mm in length are typically 119.5 mm for the internal diameter, 137.5 mm. for the outside diameter and included

  between 1.5 and 1.6mm with regard to its thickness.

  If the flat annular part 13 is the final part to be obtained, it is successively subjected to degreasing, drying and oiling. The oil in part 13 is

  only carried out to protect it during transport.

  In the case where it is desired to obtain a frustoconical annular part, the flat annular part 13 obtained in the previous step is subjected to a second operation

of fornage to the press.

  For this purpose, it is positioned in a second tool 18 of which only the upper 19 and lower 20 dies are shown diagrammatically in position

shown in Figure 5.

  The lower die 20 has a cylindrical central part 20A and an annular peripheral part 20B for forming. The central part 20A is raised relative to the peripheral part 20B and has a diameter slightly smaller than the inside diameter of the flat annular part 13 so that by positioning the part 13 on

  the lower die 20, the part 13 is automatically centered.

  The upper die 19 comprises on the one hand a cylindrical central housing 19A for centering substantially complementary to the central part 20A of the lower die 20 and on the other hand a peripheral annular punch 19B intended for

  cooperate with the peripheral part 20B during forming.

  The punch 19B has a flat and annular forming surface 19C which is radially inclined downwards. The peripheral part 20B has a forming surface 20C which is planar and parallel to the forming surface 19C with the exception of an external edge 20D bent upward to obtain an external rounded edge of the final part. The exact shape of forming surfaces 190 and 20C depends on the

  shape and final dimensions of the part to be obtained.

  During this phase of the process, the flat annular part 13 is com-

  awarded between the two matrices 19 and 20 to obtain a frustoconical annular part 23

  as shown in Figure 6.

  Then, we submit this frustoconical annular part 23 successively

  degreasing, drying and oiling.

  Figure 7 shows the part 23 in cross section. It resembles a large "Belleville" type elastic washer. Its cross section

  has two large sides 24 and 25 substantially parallel to each other.

  As shown in more detail in FIG. 8, the part 23 has a small interior side 26 slightly rounded and a small exterior side 27 whose profile is rounded according to a profile determined by the shape of the forming surface 20C of the

lower matrix 20.

  Of course, the method of the invention can easily be adapted to obtain frustoconical annular parts of varied cross section by conforming to

  will the forming surfaces 19C and 20C of the press 18.

  Figure 9 shows in a view similar to that of Figure 8 an example of a variant of the part 23. The cross section of this part 23 has two large sides 24 and 25 substantially parallel to each other, a small inner side 28 rectilinear , substantially parallel to the axis of the part, and a small outer side 27 formed by

  an arc connecting the long sides 24 and 25 and extending over approximately 90 '.

  In a simplified variant of the process, provision is made to produce the part

  frustoconical annular during a single forming operation.

  To this end, the annular blank 6 is positioned directly on the lower die 20 of the second tool 18 and it is compressed to obtain an annular part.

  frustoconical 23 shown in FIG. 10 in a view similar to that of FIG. 9.

  This piece 23 has in cross section a shape identical to that shown in Figure 9 except for a burr 29 located on the small outer side 27 which is due to an excess of material on the periphery during compression of the 'blank 6. It is therefore understood that the method according to the invention allows to realize more economically flat or frustoconical annular parts since on the one hand the number of steps to obtain the desired part has been significantly reduced compared to the methods known, and on the other hand, this process does not generate falls. Furthermore, the step

  polluting tribofinishing the part could be removed using the method according to the invention.

  In addition, the parts manufactured according to the method of the invention can be produced with greater precision and with better homogeneity of the

  mechanical characteristics than those manufactured according to known methods.

  Of course, the flat or frustoconical annular part produced according to the method of the invention is capable of other uses than that mentioned in the

preamble for a clutch.

Claims (12)

  1. Method for manufacturing a flat annular (13) or frustoconical part (23), characterized in that it comprises the following steps: * a section (2) is cut from a metal wire (1) of predefined length , - this section (2) of wire is bent to form a torus (3), - the two ends (4,5) of this torus are welded to obtain an annular blank (6), and   - Said blank (6) is compressed by means of a tool (7) to form said part (13; 23).   2. Method according to claim 1, characterized in that a flat annular part (13) is formed by compressing said blank (6) in a single operation of press forming.   3. Method according to claim 2, characterized in that a frustoconical annular part (23) is formed by compressing the flat annular part (13) during a   additional press forming operation.   4. Method according to claim 1, characterized in that a   frustoconical annular part (23) in a single press forming operation.   5. Method according to any one of claims 1 to 4, characterized   in that the two ends (4,5) of the toroid (3) are welded without adding metal.   6. Method according to any one of claims 1 to 5, characterized   in that the steps of cutting, bending and welding are carried out in one cycle automatic on the same machine.   7. Method according to any one of claims 1 to 6, characterized   in that after having welded the two ends (4,5) of the torus (3), at least the weld zone (6A) of the blank (6) is subjected to a heat treatment to homogenize the   mechanical characteristics in this area.   8. Method according to any one of claims 1 to 7, characterized   in that after obtaining the part (13,23), it is successively subjected to a   degreasing, drying and oiling.   9. Flat annular (13) or frustoconical part (23), characterized in that   that it is obtained by a process according to any one of claims 1 to 8, and in   which it includes a radial weld zone (6A).   10. flat annular part (13) according to claim 9, characterized in that the cross section of the part (13) has two long sides (14, 15)   substantially parallel to each other and two short sides (16, 17) slightly rounded.   11. Tapered annular part (23) according to claim 9, characterized in that the cross section of the part (23) has two large sides (24, 25) substantially parallel to each other, a small inner side (26) substantially parallel   to the axis of the part (23) and a small outer side (27) whose profile is rounded.   12. Use of a part (13,23) according to any one of   claims 9 to 11 as a clutch rod.