FR2527953A3 - Method of forming grooved pulley - entails pressing blank in two jaw die, shaping rim with conical roller and forming grooves with roller cutter - Google Patents

Abstract

The method uses a flat circular sheet metal blank (7) with a drilled and punch-calibrated central hole (8) for the generator shaft. The pulley body is formed by pressing the blank in a support mandrel (9) comprising a two-jaw (9,10) profiled die (12) mounted free to rotate on a centring shaft (13). The next stage entails forming the rim, using a rotating roller (14,15) with a conical rim profile. A V-section rim (20) with edge lies (21) is formed, the roller ridge (16) first contacting the centre (18) of the peripheral edge face (19) to ensure symmetry. Finally a roller (23) with circular V-section cutters (25) is used to form the grooves, acting by cutting material away and reshaping it into the required profile.

Description

PROCESS FOR OBTAINING A THROTTLE PULLEY AND THUS PULLEY
OBTAINED
The present invention relates to a process for obtaining a multi-groove pulley in particular intended for driving a generator for a motor vehicle by means of V-belts driven by a control pulley secured to a motor shaft of the vehicle. .

Known pulleys of this type are generally obtained by stamping a circular sheet metal blank in order to conform a cylindrical crown perpendicular to the initial plane of the blank in a first phase and in a second phase by fluorescent turning of the periphery of said crown. the pulley by rotary knobs provided with circular V-section teeth exerting significant pressure to make the material flow in housings corresponding to the grooves to be obtained and which are delimited or not by stiffening peripheral edges of height greater than the grooves so as to constitute an annular cage on the belt thus avoiding any risk of the belt escaping during operation.

Such pulleys have the major drawback of not being able to withstand heavy loads because the grooves being obtained by deformation of the material it is necessary to use a blank made of relatively thin sheet metal suitable for such a conformation.

In addition, the initial cylindrical crown on which the grooves are obtained, being perpendicular to the support plane, it follows that the pressure exerted on the pulley is effected on a cantilevered part.

In order to remedy these drawbacks limiting the use of such pulleys, because of their low resistance, one solution would consist in obtaining these multi-grooved pulleys by turning in a metallic mass which would thus make it possible to give the pulley the necessary thicknesses, but in in this case the cost price will be high because of the volume of material to be used and the material losses due to machining.

In addition, the weight of such pulleys would be a major handicap.

The object of the present invention is to remedy these drawbacks and to this end relates to a process for obtaining a multi-groove pulley in particular intended for driving a generator for an outomobi1e vehicle by means of trapezoidal belts driven by a control pulley secured to a motor shaft of the vehicle, remarkable process through the following manufacturing steps: cutting a flat circular blank from sheet metal; drilling and calibration by punching a central hole to allow subsequent passage of the pulley on the generator shaft; setting up and tightening the blank on a support mandrel consisting of two jaws producing a profile matrix corresponding to that of a blank of the pulley to be obtained and mounted on a centralizing shaft free to rotate; drive in rotation of the mandrel by at least one smooth rotary wheel of substantially conical profile, the apex of which is initially brought into contact with a central line of the peripheral edge of the blank to be then gradually introduced therein by pushing the material into the matrix until obtain a symmetrical rim delimited bilaterally by peripheral flanges; shaping of the grooves of the pulley by at least one wheel provided with circular knives with V-shaped section, the edge of which cuts the metal from the bottom of the rim and the lateral sides push it back until the grooves of corresponding shapes and desired depth are obtained .

The description which follows with reference to the appended drawings will make it easier to understand how the invention can be implemented.

Figures 1,2,3 and 4 are views showing the different stages of the process for obtaining a pulley according to the invention.

Figure 5 is a sectional view of a pulley obtained by the process according to the invention after mounting on a generator.

In the mounting example shown in FIG. 5, a generator 1 comprises an output shaft 2 on which is arranged a fan 3 secured in rotation by the tightening of the pulley 4 object of the invention, tightening obtained by action of the nut 5 screwing into a threaded end of the shaft 2.

The generator thus equipped can be rotated by means of a multi-V-belt 6 itself driven by a control pulley (not shown) secured to an engine output shaft of the vehicle.

The successive manufacturing stages for obtaining the pulley 4 are broken down as follows.

A circular pitpit blank 7 is cut out in a sheet of constant thickness which is drilled and then calibrated by punching.

 a central trov 8 closing the subsequent cssWge of the polished f on the shaft 2 of the generator 1.

The blank 7 thus obtained and put in place and clamped by pinching on a support mandrel 9 constituted by two jaws 10 and 11 realizing a matrix 12 of profile corresponding to that of a blank of the pulley 4 to be obtained and mounted on a centering shaft 13 free to rotate.

The drive in rotation of the mandrel 9 is ensured by two smooth rotary knobs 14 and 15 of substantially conical profile, the vertices 16 and 17 of which are initially brought into contact with a central line 18 of the peripheral edge 19 of the original blank 7, to be there then gradually introduced by pushing the material into the matrix 12 until a symmetrical rim 20 delimited bilaterally by peripheral flanges 21 so as to constitute an annular cage 22 to the belt 6 thus avoiding any risk of seizure thereof -this during its operation
The draft pulley 4 thus obtained is taken up, disassembly direction of the mandrel 9, by two other knobs 23 and 24 capable of shaping the grooves 29 by means of circular knives 25 with a V-shaped section whose edge 26 cuts the metal of the bottom of the rim 20 and the lateral sides 27 and 28 push it back until grooves 29 of corresponding shapes and desired depth are obtained, thus obtaining the final pulley 4.

Claims (1)

1) Method for obtaining a multi-groove pulley 4) in particular intended for ltentrainage of a generator (1) for a motor vehicle by means of trapezoidal belts (6) entrai ~ born by a soli4aire control pulley a motor shaft of the vehicle, a remarkable process by the following manufacturing steps: cutting a flat circular blank (7) from sheet metal, drilling and calibration by punching a central hole (8) to allow the subsequent passage of the pulley (4) on the generator shaft (2) (î); setting up and tightening the blank (7) on a support mandrel (9) constituted by two jaws (10 and 11) producing a matrix (12) of profile corresponding to that of a blank of the pulley (4 to be obtained and mounted on a centering shaft (13) free to rotate; rotary drive of the mandrel (9) by at least one smooth rotary wheel (14) of substantially conical profile, the top (16) of which is initially brought into contact with a central line ( 18) from the peripheral edge (l9) of the blank (7) to then be introduced therein gradually by pushing the material into the matrix (12) until a symmetrical rim (20) delimited bilaterally by peripheral edges (21); grooves (29) of the pulley (4) by at least one wheel (23) provided with circular knives (25) with V-shaped section, the edge (26) of which cuts the metal from the bottom of the rim (20) and the lateral sides (27 and Z85 push it back until the grooves (29) of corresponding shapes and depth are obtained desired.