FR2681267A1 - PROCESS FOR MANUFACTURING AN AXIS WITH PROFILED AXIAL PASSING ENDS, MACHINE FOR IMPLEMENTING THE PROCESS AND AXIS THUS OBTAINED. - Google Patents

Abstract

A method of manufacturing an axis whose axial passage of revolution has at its ends an enlargement with a particular profile. The machine for implementing this method comprises a die 8 mounted to slide in a fixed support 17 and able to receive and hold a blank of axis 1 by wedging; a counter-punch 7b with a profiled shoulder 13b, engaged by its point in one end of said bore 23; a movable punch 7a with a profiled shoulder 13a, suitable for engaging by its point in the other end of said bore 23; and pressure means suitable for exerting a force on said movable punch 7a so that the ends of the axial passage 3 of said axle blank 1 are compressed and deformed by stamping between said profiled shoulders 13a, 13b of the punches.

Description

Method for manufacturing an axis with profiled axial passage ends,

machine for the implementation of

process and axis thus obtained.

  The present invention relates to a method for manufacturing an axis with profiled axial passage ends, a machine for implementing the method, as well as the axes thus obtained. It is understood that these are axes whose axial passage of revolution has at its ends a widening with a particular profile, these axes being obtained starting from a blank in the form of a tube whose said

axial passage is cylindrical.

  Such axes are used in particular to ensure the connection between a connecting rod foot and an internal combustion engine piston, these axes being subjected to significant bending and ovalization forces which, due to their mounting between the bosses of the piston, are not uniformly distributed The zones between the extreme parts of the axial passage are subjected to the greatest bending and ovalization forces and must be relatively thick Consequently, the conical enlargement (or of any other profiled form) of the ends of the axial passage makes it possible to avoid an excess of material in the least stressed areas, that is to say at the level of the

piston bosses.

  To manufacture such axes, the machining process with cutting tools is already known, as a result of

  what traces of these tools remain on the

  enlarged mites of the axial passage thus produced, these traces constituting zones of initiation of ruptures as a result of the fatigue of the part.

  Consequently of a major drawback of this process.

  The object of the invention is to remedy this, and for this purpose a process of the general type defined at the start will be characterized in that it consists essentially in maintaining said axis in a sliding die, in engaging one of the ends of said axial passage of the axis on a counter punch, to engage a movable punch in the other end of said axial passage, and to exert on this movable punch, the axis then being in abutment on the

  counter-punch, an effort to be conferred by stamping

  ge, at both ends of said axial passage, the deformation

desired profile.

  Thanks to the sliding die, it can be understood that the axis or axis blank will not be rigidly held by it other than laterally, and that it will only be axially blocked by the counter-punch The forces that the two punches will exert on the respective ends of the axis will therefore be exactly equal, which will make it possible to obtain precisely, by this stamping, the desired profiled internal deformation, without favoring one end of the axis with respect to the other. Furthermore, it can be seen that the operation is carried out at one time on both ends, which is not the case with the machining process, since one end of the axis can only be machined maintaining it by the other end, while according to the invention it is only held laterally, by the sliding die, which therefore leaves the two ends of the axis accessible. No subsequent machining, and no resumption of

the room is only needed.

  This also results in a reduction in the manufacturing cost and an improvement in the mechanical characteristics of the axis obtained, insofar as the drawing of the part remains continuous, from one end to the other, this

  which is not the case when one proceeds by machining.

  It should be noted that if the initial blank was a solid part, the first operation could advantageously

3 2681267

  consist in making a tube by forging.

  The invention also relates to a machine for implementing such a method, and the axes thus obtained. An embodiment of such a machine will be described below by way of nonlimiting example with reference to the figures of the appended drawing in which: FIG. 1 represents in axial section a section of hollow axis with constant thickness constituting blank usable for the implementation of the invention; Figure 2 is an axial sectional view of the hollow axis with internal conical enlargements made from the blank of Figure 1, by the stamping operation according to the invention; Figure 3 is an axial sectional view of the finished axis, mounted between a piston and a connecting rod foot, obtained by external machining of the axis of Figure 2; Figures 4 to 7 are schematic views in axial section of a machine according to the invention, showing the different stages of the process which it implements; and figure 8 shows another example of profile

  for widening at the end of an axial axis passage.

  The rough section of axis 1 of FIG. 1, for example made of case-hardened steel, is a hollow cylinder of

  revolution at constant wall thickness.

  The axis 2 that the invention aims to obtain is shown in Figure 2; the axial passage 3 of the blank 1 has been widened at its ends by stamping, in 2 a and 2 b, according to conical surfaces (in FIG. 8, it is a rounded surface 2 c) The passage

  axial remains as is only in the central part.

  After machining its outer surface, the axis 2 can be mounted so as to ensure the connection between a connecting rod end 6 and the bosses 5 of a piston 4, in a known manner. It can be seen that there is a reduction in thickness of the axis 2 only in the least working parts, at the level of the bosses 5 of the piston, and a normal thickness in the center. The axis which has just been described can be realized

with the machine of figures 4 to 7.

  In these figures, the counter-punch has been referenced

  referenced 7 b It has at its base a head 12 b normally resting on a table 14, which has a bore 15 in which an ejector can slide 16 The movable punch has been shown at 7 a, in the axis of the preceding These punches comprise each a point, respectively l Ob and 10 a, and a profiled shoulder, in

  the conical occurrence (working part), respective-

  ment 13 b and 13 a The machine also comprises a fixed support 17 resting on a base 18 fixed on the table 14, and in which support is mounted a sliding die 8 consisting of two coaxial parts 8 a and 8 b secured by conical fitting This matrix rests on studs 19 elastically biased upwards by helical springs 20 held in

  cylindrical housings 21 of the base 18 The slide-

  ment of the matrix 8 upwards is limited by

shoulders 22.

  The central part 8b of the matrix is interchangeable, so that one can block in its alé

  central sage 23, oriented in the direction of sliding, of the blanks 1 of different diameters (The end of the counter-punch 7b is engaged in the bore 23).

  When the axis blank 1 is in place in the sliding die 8, the movable punch 7 a is lowered by a hydraulic cylinder or the like so that its tip i Qa engages at the end in the axial passage 335 of the blank 1, the tip l Ob of the counter-punch 7 b then being engaged in the other end of this passage (see

2681267

  Figures 4 and 5) The pressurization of the cylinder causes the desired deformations 2 a and 2 b with perfect balancing of the forces exerted by the conical shoulders 13 b and 13 a on the blank, since the die 8 can slide slightly towards the bottom by compressing the springs 20 (FIG. 6) Indeed, the pressure exerted by the conical shoulders of the punches on the blank 1 causes the latter to block in the bore 23 of the die, and these are therefore the forces of friction which

bring it down.

  After execution of the desired enlargements 2 a and 2 b by this stamping, the movable punch is raised, and the actuation of the ejector 16 (FIG. 7) makes it possible to raise the counter-punch 7 b and to eject the axis 2, after which the same operations can be repeated

for the next room.

6 2681267

Claims (9)

  1 Method for manufacturing an axis with profiled axial passage ends, namely the axial passage of revolution having at its ends a widening with a particular profile, starting from a blank in the form of a tube, said tube axial passage is cylindrical, characterized in that it essentially consists in maintaining said axis (1) in a sliding die (8), in engaging one of the ends of said axial passage (3) of the axis on a counter-punch (7 b), to engage a movable punch (7 a) in the other end of said axial passage, and to exert on this movable punch (7 a), the axis (1) then being in abutment on the counter-punch (7b), a specific force to be imparted by stamping, at both ends of said   axial passage (3), the desired profiled deformation.   2 machine for implementing the method of claim 1, for the manufacture of an axis with profiled axial passage ends, namely whose axial passage of revolution has at its ends a widening with a particular profile, starting from a blank in the form of a tube whose said axial passage is cylindrical, characterized in that it comprises: a matrix (8) slidably mounted in a fixed support (17) and comprising, in the direction of this sliding, a bore (23) suitable for receiving and holding a pin blank (1) by wedging; a counter-punch (7 b) with profiled shoulder (13 b), engaged by its point in one end of said bore (23); a movable punch (7a) with profiled shoulder (13a), suitable for engaging by its point in the other end of said bore (23); and pressure means capable of exerting a force on said movable punch (7 a) so that the ends of the axial passage (3) of said axis blank (1) are compressed and deformed by stamping between said profiled shoulders (13 at, 13 b) punches.   3 Machine according to claim 2, character-   sed in that said sliding die (8) rests on studs (19) resiliently recalled by springs (20) housed in a base (18) carrying said support (17).   4 Machine according to claim 2 or 3, characterized in that said sliding die (8) has stop shoulders (22) preventing it from exit from said support (17).   5 Machine according to any one of the claims.   cations 2 to 4, characterized in that said sliding die (8) consists of two coaxial parts (8 a, 8 b) secured by conical fitting and whose central part, comprising said bore (23), is interchangeable.   6 Machine according to any one of the claims.   cations 2 to 5, characterized in that it includes an ejector (16) suitable for ejecting the axis (2) from the bore (23) of the sliding die (8), via of said counter-punch (7b).   7 Machine according to any one of the claims.   cations 2 to 6, characterized in that said shoulder-   elements (13 a, 13 b) of the punches are conical.   8 Axis with profiled axial passage ends, in particular with conical widening, characterized in that it is obtained by the method of claim 1. 9 Axis with profiled axial passage ends, in particular with conical widening, characterized in that it is obtained on a machine conforming to one   any of claims 2 to 7.