EP0490840A1

EP0490840A1 - Procedure and means to realise a hub from a metal disc or similar

Info

Publication number: EP0490840A1
Application number: EP91830549A
Authority: EP
Inventors: Franco Magnoni
Original assignee: Mta Di Bompani Ivaldo & C SNC
Current assignee: Mta Di Bompani Ivaldo & C SNC
Priority date: 1990-12-12
Filing date: 1991-12-09
Publication date: 1992-06-17
Also published as: IT9040167A0; IT1242945B; IT9040167A1; CA2057182A1

Abstract

The invention relates to a procedure and means to realise a hub from a metal disc or similar. According to the invention, a disc (6), in which a central hole has already been bored, is set in motion about its own axis. Internally to the said central hole a tool (16) is inserted comprising a circular cutter (17) formed so as to penetrate into the width of the disc (6). The tool (16) is pressed against the edge of the central hole and is made to advance radially in such a way as to produce the cutting and separation, or opening, of the disc (6) into two sheets, or leaves (18) which are then made to divide and are arranged so as to generate tracts of cylindrical surface which are coaxial with the disc (6) rotation axis.

Description

Object of the present invention is a procedure and means to realise a hub from a metal disc or similar.
In particular, but not exclusively, the invention finds application in the production of wheels, pulleys and similar obtained by starting from metal discs and subjecting them to plastic deformation. In the prior art, the problem of realising, in such types of wheel, a hub necessary for permitting of coupling the wheel on to shafts or pivots, is solved with types of solutions that increase total production costs considerably. One of the most frequent solutions is to realise the wheelhub or pulley hub, bored into the metal disc, by means of use of a tubular element or bushing which can be solidly connected to the body of the wheel or pulley by means of traditional-type welding or by forced coupling with the shaft or pivot predisposed. Other variants envisage the application of the said bush by means of friction-welding processes.
The present invention as characterised in the claims which follow proposes to solve the above-described problem without resorting to the use of hubs or bushings prepared independently, whose application requires operations which render the production process complicated and therefore production costs high.
Further characteristics and advantages of the invention will better emerge from the detailed description that follows, of some preferred but not exclusive embodiments of the invention, illustrated in the form of non-limiting examples in the accompanying drawings, in which:

Figure 1 shows a vertical-plane schematic section;
Figure 2 shows in enlarged scale a part of the section of figure 1, represented in a different operative configuration;
Figures 3 and 4 show, in two different operative configurations, the same schematic axial section of a second embodiment of the invention.

With reference to the illustrations, 1 indicates a fixed frame on which a principal chuck 2 is mounted, which principal chuck 2 is commanded to rotate about a fixed vertical axis by a motor 3, to which it is connected by means of a mechanical transmission of the chain type 4. The chuck 2 is equipped with a self-centering mounting device 5 predisposed and equipped to grip metal discs 6 at their edges. A strong transversal slide 7 is slidingly driven in a perpendicular direction to the axis of the chuck 2 along horizontal guides 8. The sliding movements of the slide 7 are commanded by a double-acting hydraulic cylinder 9. A turning head 10 is mounted on the slide 7, which turning head 10 has its rotation axis parallel to the rotation axis of the principal chuck 2. On the same slide 7 a vertical guide 11 is also mounted, on which vertical guide 11 a vertical slide 12 is vertically slidably mounted and has a coalligned counterhead 13, that is, coaxially arranged with the turning head 7. The vertical slide 12 is vertically slidably driven by means of a double-action hydraulic cylinder 14 whose stem constitutes the said vertical guide 11. The turning head 10 and the relative counterhead 13 are positioned, with respect to the principal chuck 2, in such a way that their common axis is comprised inside the cavity existing internally to the said principal chuck 2. The turning head 10 and the counterhead 13 are arranged in such a way as to permit of rotatable coupling with the two ends of a toolhead shaft 15 on which a tool 16 is arranged, said tool 16 being a knife or circular cutter 17 conformed and of such a size as to be able to penetrate into the width of the metal sheet constituted by the disc 6, so that a partial separation into two sheets 18 is produced. The tool 16 is shaped in such a way as to present on both sides of the circular cutter 17 two turning surfaces constituted by the flanks 20 of the said circular cutter 17, which flanks 20 are shaped gradually curvedly towards the central cylindrical body of the said tool 16 where the end at two coaxial portions of cylindrical surface 22. The said cylindrical surfaces 22 are simply two portions of the external cylindrical surface of the tool 16 itself, solid with the toolhead shaft 15. In particular, the profile of the two flanks 20, observable in any axial section of the said tool, comprises a section of curve which has its concavity externally facing.
The metal disc 6 is placed on the principal chuck 2 and gripped by the self-centring gripping device 5 in such a way that it is perfectly solid to the check 2. The disc 6 has a central hole 19 which hole's 19 diameter is slightly greater than that of the circular cutter 17, in order to permit of the cutter's 17 free introduction internally to the hole 19. The tool 16 is positioned so that the circular cutter 17 is located before the edge of the central hole 19 at the half-point of the width of the disc 6. The interaction between the tool 16 and the disc 6 happens when the said disc 6 is placed solidly in rotation by the principal chuck 2 at a pre-established speed. By action of the cylinder 9 on the transversal slide 7 drive is transmitted which consists in a displacement of the tool 16, and therefore of the circular cutter 17 in a radial direction with respect to the rotation axis of the principal chuck 2. The action of the circular cutter 17 produces the cutting of the metal disc 6 and its subsequent splitting into two leaves or sheets 18 which are deformed according to the conformation of the circular cutter 17 up until they arrive at the two cylindrical portions 22, placed at the two sides as a continuation of the two flanks 20 of the cutter 17.
The penetration movement of the cutter 17 into the width of the disc 6 therefore produces the formation, in a single body made from the disc 6, of a hub having a form which is clearly observable in figure 2 and which is constituted of the two leaves or sheets 18.
In figures 3 and 4 part of a second embodiment is represented, which envisages the use of a hollow chuck 30, driven to rotate about a fixed axis and having coupled internally to it with free relative rotation a tubular cylindrical element (bushing) 31. The free relative rotation is guaranteed by bearings 26. The bushing 31 has in its turn a cylindrical cavity 32 which is not coaxial in which a toolhead shaft 33, also freely rotatable, is coupled. The toolhead shaft 33 is predisposed to receive a projectingly mounted tool 16'. In fact, said toolhead shaft 33 is equipped with a hollow cylindrical housing 35 which has a parallel axis to that of the toolhead shaft 33, but which is eccentrically arranged, with a pre-established eccentricity with respect to the said toolhead shaft 33. The tool 16' is equipped with a cylindrical spigot 34 predisposed for coupling internally to the said cylindrical housing 35 by means of the interpositioning of bearings 27.
The metal disc 6 is gripped on the chuck 30 by means of a sort of counterchuck 36 coaxially arranged in front of the chuck 30.
The chuck 30 and the counterchuck 36 rotate solidly and freely with respect to the tubular element 31, which tubular element 31 is rotatingly independent of said chucks 36 and 30. The radial advancement of the tool 16' is obtained in a very simple way, gradually realising a relative rotation between the toolhead shaft 33 and the tubular element 31 through means not indicated in the figures. A relative rotation of the toolhead shaft 33 with respect to the tubular element 31 produces a variation in the total eccentricity of axis of the tool 16' with respect to the rotation axis of the hollow chuck 30.
The last embodiment illustrated is particularly suitable for the making of hubs of small diameter and in any case for a first cutting operation beginning from an initial hole 19, of small dimensions, arranged on the metal disc 6.

Claims

A procedure and means to realise a hub from a metal disc or similar comprising:
- a pre-bored central hole in a metal disc (6);

- the setting in rotation of the said disc (6) about its own axis;

- the insertion, internally to said central hole (6) of a special tool (16)(16') equipped with at least one circular cutter (17) conformed in such a way as to penetrate into the width of the said disc (6) in order to produce a partial separation of said disc (6) into two leaves or sheets (18);

- the interaction between said disc (6) and said tool (16) (16'), against the edge of the said central hole (19) according to a radial relative displacement direction, to realise the said separation of the disc (6) into two sheets (18);

- the further separating of the two said sheets (18) through the continuance of the action of the said tool (16) (16') until the said sheets (18) are at least in part parallel to the rotation axis of the disc (6) in such a way as to create portions of internal cylindrical surfaces which are coaxial with the said rotation axis.
A procedure as in claim 1 wherein it is envisaged that said special tool (16) (16') has on both sides of the said circular cutter (17) two revolving surfaces or flanks (20) which are shaped gradually curvedly towards the central cylindrical body of the said tool (16) (16'); the profile of the said two flanks (20), observable in any axial section of the said tool (16) (16'), being constituted by a portion of curve which, at least with respect to the connecting area with the said central cylindrical body, has its concavity facing externally.
A procedure as in claim 2 wherein said special tool (16) (16') is free in rotation about its own axis, which axis is parallel to the rotation axis of the said disc (6).
A machine aimed at realising the procedure of claim 1, comprising:
- a fixed frame (1) on which a principal chuck (2) is mounted, said chuck (2) being hollow and made to rotate about a fixed axis, and being equipped with an automatic self-centering device (5) to grip, in particular, metal discs (6);

- a strong transversal slide (7) slidably driven in a perpendicular direction with respect to the rotation axis of the said principal chuck (2), on which slide (7) a turning head (10) is mounted, said head (10) having its axis parallel to the said rotation axis and being aimed at permitting of coupling with the first of the two ends of a toolhead shaft (15) on which a tool (16) is arranged, which tool (16) is equipped with a knife or circular cutter (17);

- a slide (12) mounted on the said transversal slide (7) and slidably driven in a parallel direction to the rotation axis of the principal chuck (2); said slide (12) having solidly coupled to it a counterhead (13), coaligned with the said turning head (10) and predisposed to constrain the second end of the said toolhead shaft (15) on which the said tool (16) is arranged;
said head (10) and said counterhead (13) being positioned with respect to the said principal chuck (2) in such a way that the common axis described by them is comprised internally to the said principal chuck (2).
A machine as in claim 3 wherein said transversal slide (7) is driven in its sliding movements by a double-action hydraulic cylinder (9).
A machine as in claim 2 wherein said slide (12) is commanded to slide in a parallel direction to the rotation axis of the said principal chuck (2) by a double-action hydraulic cylinder (14) whose stem has one end fixed to the said transversal slide (7).
A machine as in claim 2, wherein said tool (16) is mounted on said toolhead shaft (15) and is equipped with a said knife or circular cutter (17) whose flanks (20), constituted by the said turning surfaces, are symmetrical with respect to the median perpendicular plane of the rotation axis which contains the cutter (17), said flanks connecting with two portions of cylindrical surfaces (22) coaxial with the rotation axis of the said circular cutter (17).
A machine as in claim 7 wherein the said two portions of circular cylindrical surface (22) have the same diameter.
A machine for the procedure of claim 1 comprising a hollow chuck (30), which is driven to rotate about a fixed axis and has, coupled internally to it with free relative rotation, a cylindrical tubular element (bushing) (31); said tubular element (31) having in its turn a non-coaxial cylindrical cavity (32) in which a toolhead shaft (33) is coupled, with free relative rotation, said toolhead shaft (33) being predisposed to receive a said tool (16'); its being envisaged that the said tool (16') be mounted projectingly on said toolhead shaft (33) in an eccentric position with respect to said toolhead shaft (33).