FR2818174A1 - METHOD FOR MANUFACTURING AN IGNITION CAGE - Google Patents

Abstract

The invention provides a method of manufacturing an axial cylindrical ignition cage (18) which is intended to form part of an engine flywheel (10) of a motor vehicle and which comprises on its periphery at least one peripheral mark (24 ) forming a target for adjusting the ignition of the engine, of the type which comprises at least one step of deformation, parallel to the axial direction, of an edge (34) in the form of a crown of a blank (32) initially in flat disc shape, and a step of notching this edge (34) which is intended to produce said at least one peripheral mark (24 of the cage, characterized in that it successively comprises a first step of notching flat of the blank (32), a second step of folding the edge (34) of the blank (32) parallel to the axial direction (A), and a third step of calibrating the edge (34) of the blank (32).

Description

<Desc / Clms Page number 1>

"Method of manufacturing an ignition cage"
The invention relates to a method of manufacturing an ignition cage.

 The invention relates more particularly to a method of manufacturing an axial cylindrical ignition cage which is intended to form part of a flywheel of a motor vehicle and which comprises on its periphery at least one peripheral mark forming a test pattern for adjusting the the ignition of the engine, of the type which comprises at least one deformation step, parallel to the axial direction, of a crown-shaped edge of a blank initially in the form of a flat disc, and a notching step of this edge which is intended to produce said at least one peripheral marker of the cage.

 In known manner, an ignition cage intended to form part of a vehicle engine flywheel comprises a central part in the form of a flat disc and a peripheral part in the form of a crown which comprises on its cylindrical edge at least one notch forming a test pattern. 'ignition.

 Conventionally, this cage is obtained according to a manufacturing process comprising four successive stages.

 In a first step, a plane disc-shaped blank is stamped axially so as to create on its periphery a parallel annular ring which is offset axially with respect to the initial plane of the disc-shaped blank.

 In a second step, this crown is cut in the axial direction using a clipping tool.

 In a third step, the remaining edge fell in the axial direction by a stamping tool so as to create the crown of the cage, the cylindrical peripheral edge of which is of axial orientation.

 Finally, in a fourth and final step, notches are made on the peripheral edge using a notching tool, which is mounted on a machine which includes a

<Desc / Clms Page number 2>

 divider mandrel which is radially movable, so as to obtain notches spaced at regular angular intervals.

 Such a method has many drawbacks.

 An ignition cage of the type described above cannot admit a cylindrical defect greater than the 0.15 mm cylindrical tolerance. However, such a process causes, during its various stages, a significant deformation of the outer diameter of the crown, which is incompatible with the aforementioned tolerance.

 In addition, the fourth step of notching causes burrs and significant dispersions on the positioning of the notches.

 To overcome these drawbacks, the invention proposes a new manufacturing process during which the notches are produced during a flat notching operation of the blank.

 To this end, the invention provides a method of the type described above, characterized in that it successively comprises a first step of flat notching of the blank, a second step of folding the edge of the blank parallel to the axial direction, and a third step of calibrating the edge of the blank.

 According to other characteristics of the invention: - each of the steps is carried out in a single pass, - during the first step of flat notching, a notching matrix, which comprises a plurality of cutting teeth axial orientation distributed angularly in a regular manner, is pressed coaxially against the blank in the form of a flat disc to produce a plurality of notches on the outer peripheral edge of the blank, - during the second step of folding the edge of the blank parallel to the axial direction, a first tool for guiding the sides of the blank notches is inserted into the notches in the blank and a tool for folding the edge of the blank is pressed coaxially against the edge of the blank,

<Desc / Clms Page number 3>

- le premier outil de guidage des flancs d'encoches présente la forme d'un peigne de révolution comportant sur sa périphérie une pluralité de dents de guidage d'orientation axiale qui sont destinées à pénétrer dans les encoches précédemment découpées de manière à guider leurs flancs radiaux lors de la deuxième étape de repli du bord du flan parallèlement à la direction axiale, - l'outil de repli comporte au moins une surface intérieure de repli dans laquelle est pratiquée une pluralité de lumières d'orientation axiale réparties angulairement de manière régulière qui sont destinées à permettre le passage de l'outil de repli entre les dents de guidage du premier outil de guidage des flancs d'encoches, et ladite surface intérieure de repli présente la forme d'un tronc de cône, dont la conicité est orientée à l'opposé du flan, dont un diamètre inférieur est égal au diamètre de la périphérie du flan initial, et dont un diamètre supérieur est égal au diamètre extérieur de la cage à obtenir, - l'outil de repli du bord du flan n'est pressé sur le flan qu'en même temps que le premier outil de guidage des flancs d'encoches est reçu dans lesdites encoches ou après que le premier outil de guidage des flancs d'encoches ait été reçu dans lesdites encoches, - au cours de la troisième étape de calibrage du bord du flan, un deuxième outil de guidage des flancs d'encoches du flan est inséré dans les encoches du flan et un outil de calibrage du bord du flan est mû axialement le long du bord replié du flan, - le deuxième outil de guidage des flancs d'encoches présente la forme d'un peigne de révolution comportant sur sa périphérie une pluralité de dents de guidage d'orientation axiale qui sont destinées à pénétrer dans les encoches précédemment découpées de manière à guider leurs flancs radiaux lors de la troisième étape de calibrage du bord du flan, - l'outil de calibrage comporte au moins une surface intérieure de calibrage qui comporte une partie supérieure

- The first tool for guiding the sides of notches has the shape of a comb of revolution comprising on its periphery a plurality of guide teeth of axial orientation which are intended to penetrate into the notches previously cut so as to guide their sides radial during the second step of folding the edge of the blank parallel to the axial direction, - the folding tool comprises at least one interior folding surface in which is formed a plurality of axially oriented openings distributed angularly in a regular manner which are intended to allow the passage of the folding tool between the guide teeth of the first tool for guiding the sides of the notches, and said internal folding surface has the shape of a truncated cone, the conicity of which is oriented at the opposite of the blank, whose smaller diameter is equal to the diameter of the periphery of the initial blank, and whose larger diameter is equal the outside diameter of the cage to be obtained, the tool for folding the edge of the blank is pressed on the blank only at the same time as the first tool for guiding the sides of the notches is received in said notches or after the first tool for guiding the sides of the notches has been received in said notches, - during the third step of calibrating the edge of the blank, a second tool for guiding the sides of the blank notches is inserted in the notches of the blank and a tool for calibrating the edge of the blank is moved axially along the folded edge of the blank, the second tool for guiding the sides of the notches has the shape of a comb of revolution comprising on its periphery a plurality of guide teeth of axial orientation which are intended to penetrate into the notches previously cut so as to guide their radial sides during the third step of calibrating the edge of the blank, - the calibration tool comprises at least one internal surface higher calibration which has an upper portion

<Desc / Clms Page number 4>

 cylindrical, the diameter of which is greater than the diametrical size of the guide teeth of the second guide tool and equal to the final external diameter of the cage to be obtained, and of which a frustoconical lower part, of conicity oriented upwards, is intended to allow the rolling of the beads resulting from the deformation of the blank during the second step of axial folding of the edge of the blank, - the calibration tool is moved axially along the folded edge of the blank only at the same time as the second tool for guiding the sides of notches is received in said notches or after the second tool for guiding the sides of notches has been received in said notches.

 Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: - Figure 1 is an overall perspective view of a steering wheel engine comprising an ignition cage obtained by the process which is the subject of the invention, - Figure 2a is an axial section view illustrating the first stamping step according to a conventional process for obtaining the cage, - Figure 2b is an axial sectional view illustrating the second trimming step according to the conventional method for obtaining the cage, - Figure 2c is an axial sectional view illustrating the third falling step according to the conventional method for obtaining the cage, - FIG. 2d is an axial section view illustrating the fourth step of notching according to the conventional method of obtaining the cage, - FIG. 3a is an axial section view illustrating the first re flat notching step of the blank according to the method of the invention,

<Desc / Clms Page number 5>

 - Figure 3b is an axial sectional view illustrating the second step of folding the edge of the blank according to the method of the invention, and - Figure 3c is an axial sectional view illustrating the third step of calibrating the edge of the blank according to the process which is the subject of the invention, - Figure 3d is a detail view, in the vicinity of the edges of the blank, of Figure 3c.

 In the following description, identical reference numerals designate identical parts or having similar functions.

 There is shown in Figure 1 the assembly of a flywheel 10 for a spark ignition engine produced in accordance with a prior art.

 In known manner, the flywheel 10 is substantially axial with axis A and it is intended to be fixed, to the left of FIG. 1, at the rear of a crankshaft (not shown) of a heat engine of the vehicle.

 To this end, the flywheel 10 comprises a drive plate 12 in the form of a disc, the holes 14 of which, angularly distributed regularly around the axis A, allow the passage of screws (not shown) for fixing the flywheel. 10 to the engine crankshaft.

 In known manner, the flywheel 10 comprises at least one support 16 in the form of a disc, which, on the one hand, carries an ignition cage 18, a toothed launch ring 20, and an inertia element 22, and which, on the other hand, is fixed to the drive plate 12 to allow modular mounting of ignition cages 18, launching rings 20 and different inertia elements 22, each adapted to a specific engine, on a support 16 and a common drive plate 12.

 The axial cylindrical ignition cage 18 has on its periphery notches 24 forming a test pattern for adjusting the ignition of the vehicle engine.

<Desc / Clms Page number 6>

 More particularly, the flywheel 10 comprises for example, from front to back, that is to say from left to right of FIG. 1, a washer 28 for fixing the drive plate 12 on the support 16 , the drive plate 12, the ignition cage 18, a spacer 30 the launching ring 20, the support 16 and finally the element 22 of inertia.

 The detail of the fixing of these various elements is not the object of the present invention, it will not be described in more detail.

 Conventionally, the production of an ignition cage 18 of the type previously described is carried out as described with reference to Figures 2a, to 2d.

 In a first step, shown in FIG. 2a, a planar blank 32 in the form of a disc is pressed axially, using a stamping die 33 moved along the arrow "Emb 1", so as to create on its periphery an annular ring 34, parallel to the plane of the blank 32, which is offset axially with respect to the initial plane of the disc-shaped blank 32.

 In a second step, shown in FIG. 2b, this crown 32 is cut in the axial direction using a trimming tool 35. This second step, represented by the arrow "Det 2", produces a clipping drop 36 and makes it possible to obtain an annular crown 34 of regular outline.

 In a third step, shown in Figure 2c, the annular ring 34 forming the remaining edge fell in the axial direction A using a falling tool 38 moved along the arrow "Tomb 3" so as to create the crown of the cage, the cylindrical peripheral edge 34 of which is of axial orientation.

 Finally, in a fourth and final step, shown in FIG. 2d, notches 24 are produced on the peripheral edge 34 of the cylindrical ring using a notching tool 42, which is movable radially along the arrow " Enc 4 "and which mounted on a machine (not shown) comprising a mandrel

<Desc / Clms Page number 7>

 divider, so as to obtain notches 24 spaced at regular angular intervals. The cutting of each notch 24 produces a fall 44 of notching.

 Such a process causes, during its different stages, a significant deformation of the outer diameter of the crown, which is incompatible with the tolerances required for the cage 18. In addition, the fourth step of notching causes burrs and significant variations in the positioning of the notches 24.

 To remedy these drawbacks, the invention proposes a new manufacturing method which is shown with reference to FIGS. 3a to 3d.

 According to the invention, the method comprises a first step of flat notching of the blank 32, a second step of folding the edge 34 of the blank parallel to the axial direction, and a third step of calibrating the edge 34 of the blank 32.

 Advantageously, each of these steps is carried out in a single pass.

 As illustrated in FIG. 3a, during the first step of flat notching, a notching matrix, which comprises a plurality of cutting teeth 46 of axial orientation distributed angularly in a regular manner, is pressed coaxially along the arrow "Enc 1" against the blank 32 in the form of a flat disc to produce a plurality of notches 24 on the peripheral edge 34 outside of the blank 32. This first step produces notching drops 44.

 This first step allows all the notches 24 to be produced in a single pass. The notches 24 being produced simultaneously by all the teeth 46 of the notching matrix, the positioning dispersions of the notches are only the result of possible positioning deviations of the teeth 46 relative to one another, due for example to the bending of the teeth 46, and not, as in the previous method, deviations from

<Desc / Clms Page number 8>

 repositioning of the notching tool 42 on the divider mandrel of the notching machine.

 Then, during the second step of folding the edge 34 of the blank parallel to the axial direction, a first tool 35 for guiding the sides of the blank notches is inserted into the notches 24 of the blank. In this same step, a tool 50 for folding the edge 34 of the blank is pressed coaxially against the edge 34 of the blank so as to fold it perpendicular to the blank 32.

The two tools 35 and 52 are moved axially along the arrow "Rep 2" in FIG. 3b.

 Advantageously, the first tool 35 for guiding the sides of the notches has the shape of a comb of revolution comprising on its periphery a plurality of teeth 48 for guiding in axial orientation which are intended to penetrate the notches 24 previously cut so to guide their radial sides during the second step of folding the edge of the blank parallel to the axial direction A.

 The fallback tool 50 has at least one interior fallback surface in which is formed a plurality of axially oriented slots 52 which are angularly distributed in a regular manner. These slots 52 are intended to allow the passage of the folding tool between the guide teeth 48 of the first tool 35 for guiding the sides of the notches.

 The inner surface 54 of the tool 50 has the shape of a truncated cone, the conicity of which is oriented opposite to the blank 32, of which a smaller diameter "Dso" is equal to the diameter of the periphery of the blank 32 initial, and with a diameter greater than "050" equal to the outside diameter of the cage 32 to be obtained.

 Advantageously, the tool 50 for folding the edge 34 of the blank is only pressed on the blank 32 at the same time as the first tool 35 for guiding the sides of the notches is received in said notches 24 or only after the first tool for guiding the sides of the notches has been received in said notches 24. In this way, during the second step, the sides of the notches

<Desc / Clms Page number 9>

 24 are always guided by the first guide tool during the folding of the edge 34 of the blank, and therefore the folding of this edge 34 does not cause any deformation of the notches 24.

 During the third step of calibrating the edge 34 of the blank, a second tool 53 for guiding the sides of the blank notches is inserted into the notches 24 of the blank 32 and a tool 55 for calibrating the blank edge is moved axially the along the folded edge 34 of the blank 32. The two tools 53 and 55 are moved axially along the arrow "Cal 3" in FIG. 3c.

 Advantageously, as illustrated in FIG. 3d, the second tool 53 for guiding the sides of the notches has, in a manner analogous to the first tool 35, the shape of a comb of revolution comprising on its periphery a plurality of teeth 56 axial orientation guide which are intended to penetrate the notches 24 previously cut so as to guide their radial sides during the third step of calibrating the edge 34 of the blank 32.

 In addition, the calibration tool 55 comprises at least one interior calibration surface 58 which comprises a cylindrical upper part 60 whose diameter is greater than the diametrical size of the guide teeth 56 of the second guide tool 53. The diameter of the internal surface 58 is also equal to the final external diameter of the cage 18 to be obtained.

 Advantageously, a frustoconical lower part 62 of the interior surface 58, of upwardly oriented conicity, is intended to allow the rolling of the beads resulting from the deformation of the blank 32 during the second step of axial folding of the edge 34 of the blank 32 .

 Advantageously, the calibration tool 55 is moved axially along the folded edge 34 of the blank 32 only at the same time as the second tool 53 for guiding the sides of notches is received in said notches 24 or only after the second guide tool 53 of the sides of the notches has been received in

<Desc / Clms Page number 10>

 said notches 24, so as to prevent the calibration of the edges 34 of the blank 32 from causing deformation of the teeth 24.

 The invention therefore makes it possible to obtain, at a lower cost, a cage 18 free from dispersions in positioning of its notches 24 and from cylindrical defects.

Claims (11)

 CLAIMS 1. Method of manufacturing an axial cylindrical ignition cage (18) which is intended to form part of a flywheel (10) of a motor vehicle and which comprises on its periphery at least one peripheral reference (24) forming target for adjusting the engine ignition, of the type which comprises at least one deformation step, parallel to the axial direction, of an edge (34) in the form of a crown of a blank (32) initially in the form of flat disc, and a step of notching this edge (34) which is intended to produce said at least one peripheral mark (24 of the cage, characterized in that it successively comprises a first step of notching the flat blank (32), a second step of folding the edge (34) of the blank (32) parallel to the axial direction (A), and a third step of calibrating the edge (34) of the blank (32).  2. Method according to the preceding claim, characterized in that each of the steps is carried out in a single pass.  3. Method according to claim 1 or 2, characterized in that, during the first flat notching step, a notching matrix, which comprises a plurality of cutting teeth (46) of axial orientation distributed angularly is regularly pressed coaxially against the blank (32) in the form of a flat disc to produce a plurality of notches (24) on the outer peripheral edge (34) of the blank (32).  4. Method according to the preceding claim, characterized in that, during the second step of folding the edge (34) of the blank (32) parallel to the axial direction (A), a first tool (35) for guiding the sides blank notches (32) is inserted into the notches (24) of the blank (32) and in that a tool (50) for folding the edge (34) of the blank (32) is pressed coaxially against the edge ( 34) of the blank (32).  5. Method according to the preceding claim, characterized in that the first tool (35) for guiding the sides of the notches <Desc / Clms Page number 12>  has the shape of a comb of revolution comprising on its periphery a plurality of teeth (48) for guiding an axial orientation which are intended to penetrate into the notches (24) previously cut so as to guide their radial sides during the second step of folding the edge (34) of the blank (32) parallel to the axial direction (A).  6. Method according to claims 4 or 5, characterized in that the folding tool comprises at least one inner surface (54) of folding in which is formed a plurality of lights (52) of axial orientation distributed angularly in a regular manner which are intended to allow the passage of the folding tool (35) between the teeth (48) for guiding the first tool (35) for guiding the sides of the notches, and in that said internal folding surface (54) has the shape of a truncated cone, the conicity of which is oriented away from the blank (32), whose smaller diameter (d5o) is equal to the diameter of the periphery of the initial blank (32), and whose diameter upper (Dso) is equal to the outside diameter of the cage (18) to be obtained.  7. Method according to one of claims 5 or 6, characterized in that the tool (50) for folding the edge of the blank is pressed on the blank (32) only at the same time as the first tool (35 ) for guiding the sides of the notches is received in the said notches (24) or after the first tool for guiding the sides of the notches has been received in the said notches (24).  8. Method according to the preceding claim, characterized in that, during the third step of calibrating the edge (34) of the blank (32), a second tool (53) for guiding the sides of the notches of the blank is inserted into the notches (24) of the blank (32) and in that a tool (55) for calibrating the edge (34) of the blank (32) is moved axially along the folded edge (34) of the blank (32).  9. Method according to the preceding claim, characterized in that the second tool (53) for guiding the sides of the notches has the shape of a comb of revolution comprising on its periphery a plurality of teeth (56) of <Desc / Clms Page number 13>  axial orientation guide which are intended to penetrate into the notches (24) previously cut so as to guide their radial sides during the third step of calibrating the edge (34) of the blank (32).  10. Method according to the preceding claim, characterized in that the calibration tool (55) comprises at least one internal surface (58) for calibration which comprises a cylindrical upper part (60) whose diameter is greater than the diametrical size. teeth (56) for guiding the second guide tool (53) and equal to the final outside diameter of the cage (18) to be obtained, and of which a lower frustoconical part (62), of conicity oriented upwards, is intended to allow the rolling of the beads resulting from the deformation of the blank (32) during the second step of axial folding of the edge (34) of the blank (32).  11. Method according to one of claims 9 or 10, characterized in that the calibration tool (55) is moved axially along the folded edge (34) of the blank (32) only at the same time as the second tool (53) for guiding the sides of notches is received in said notches (24) or after the second tool (53) for guiding the sides of notches has been received in said notches (24).