EP0870559A2

EP0870559A2 - Apparatus for producing a spherical element for the head of a ball joint

Info

Publication number: EP0870559A2
Application number: EP98106366A
Authority: EP
Inventors: Innocenzo Triolo; Claudio Salerno
Original assignee: Chiavette Unificate SRL
Current assignee: Chiavette Unificate SRL
Priority date: 1997-04-08
Filing date: 1998-04-07
Publication date: 1998-10-14
Also published as: IT1292849B1; ITBO970209A1; ITBO970209A0; EP0870559A3

Abstract

Apparatus (1) for producing a ball element (2) for a ball joint head, the said ball element (2) being provided with a central through hole (24), the apparatus (1) being characterised in that it comprises:

a cutting station for producing substantially cylindrical metal workpiece blanks;
at least one cold forming station (30, 40, 50, 60) for cold forming the said metal blanks;
a shearing station (70) in which a central part (23) of the workpiece is sheared;
means for displacing the workpiece to and from the cutting station, the cold forming stations (30, 40, 50, 60) and the shearing station (70); and
a control unit (10) for controlling the operations.

Description

The present invention relates to apparatus for producing a spherical element for the head of a ball joint.

Such a ball joint (according to the DIN 648 K regulations) generally comprises a main body which can be connected to an associated control rod and provided at its end with a cylindrical seat, and a spherical head which can be connected to a further rod and coupled to the body by the interposition of a bush of anti-friction material positively engaging the said seat.

For a detailed description of the head of a ball joint of this type reference is made to Italian Patent Application No. BO93A000265 in the name of the same Applicant.

Normally balls of this type are obtained by machining to remove material, starting from a steel bar of 34 Cr 4 steel or 100 Cr 6 steel. Such a manner of production however involves extremely high manufacturing costs which are of a significance which cannot be ignored. In fact, during machining to remove material a significant quantity of material remains unused in that it is in the form of cutting chips the subsequent recovery of which is extremely onerous. Moreover, the production method described above involves the use of a significant number of machine tools combined in a working "island", which, as well as being relatively expensive in themselves, involve operating and maintenance costs which cannot be ignored and which significantly increase the unit costs of the ball joint.

The present invention essentially comprises a series of arrangements which, although individually known, together confer on the apparatus in question a great reliability, which makes it possible for it to be completely automated. Among other things the ball joints obtained by means of the present apparatus are absolutely free from working defects such as internal cracks, fractures etc. Finally, the ball joint elements obtained by the apparatus have a significantly lower production cost than such products made using traditional apparatus for removing material by machining.

Therefore the present invention relates to apparatus for the production of a ball element for the head of a ball joint, the ball element being provided with a central through hole. The apparatus is characterised in that it comprises:

a cutting station to provide substantially cylindrical metal blanks;
at least one cold forming station for forming the metal workpiece to round at least a portion of the outer surface of the metal workpiece and create simultaneously pairs of cavities on the outer surface of the metal workpiece;
a shearing station in which a central part of the workpiece is sheared off;
means for displacing the workpiece to and from the cutting station, the cold forming station and the shearing station; and
a control unit for controlling the operations.

The invention will now be described with reference to the attached drawings which illustrate a non-limitative embodiment thereof, in which:

Figure 1 is a schematic view of apparatus for the production of spherical elements to be utilised on ball joint heads (according to DIN 648K regulations);

Figure 2 illustrates, in section, the various phases through which the initial workpiece passes to obtain the finished workpiece (Figure 2e);

Figures 3 to 7 illustrate in section the various cold forming stations which constitute the apparatus shown in Figure 1.

As shown in Figure 1 the apparatus 1 which forms the subject of the present invention comprises a series of working stations 30-70 in which the various working phases take place, at the end of which the initial workpiece 2 will assume the configuration shown in Figure 2e which shows the finished element 2.

Hereinafter and in the detailed description of the present invention, by the way, the reference numeral 2 will be used both for the metal workpiece during the various working phases and for the finished element.

The various stations 30-70 are commanded and controlled by an electronic central control unit 10 which fulfils the function also of controlling the loading and discharging operations to and from the stations by means not shown in the attached figures.

The station 30 (Figure 3) in particular, at which the initial workpiece passes from the configuration of Figure 2a, is constituted by an upper punch unit 31 and a lower die unit 32. The punch unit 31 in turn is constituted by a main portion 33 to which the upper punch 34 is fixed which is able to press the workpiece into the die 35 provided in the die unit 32. This die 35 is provided with a shoulder which gives rise to the rounded corners 2s (Figure 2a). The combined action of the two

punches

34, 36 creates the cavity 22a and the cavity 21a respectively. The punch unit 31 is moved, together with the punch 34, by an actuator 37, whilst the punch 36 is moved by the associated actuator 38. The two

punches

34, 26 can therefore displace along the vertical axis of symmetry 300.

The punch 36 also acts as an extractor to extract the element 2 once this first cold forming operation has been completed.

Once the element 2 is in the space between the punch unit 31 and the die unit 32 transfer can take place via transport means, not shown in the drawings, to the following working station 40 where a further cold working of the element 2 takes place.

The working station 40 (Figure 4) comprises an upper punch unit 41 and a lower die unit 42 the movements of which are coordinated with respect to one another to perform a further cold stamping operation.

The lower punch 43 is fixed to the remainder of the die unit 42 and is surrounded by an extraction bush 44 moved by its own actuator 45 which first acts on three pins 46 (only one is visible in Figure 4). This extraction bush 44 is utilised for the extraction of the element 2 from the lower half die 47. Summarising, the actuator 45 moves the thrust spacer 48, which presses the three pins 46 which, as mentioned, are responsible for the movement of the extraction bush 44 for extracting the element 2 from the lower half die 47.

The upper half die 49, fixed to the upper part 41 is in turn subdivided into two

portions

49a and 49b fixedly connected together.

The upper pin 400 contacts against a first element 401 which, in turn, can engage against a second element 402. A spring 403 exerts a separating action between the first element 401 and the second element 402; in this way, when the upper punch unit 41 is completely raised the pin 400 projects and serves to press the elements 2, carried by pincer means (not shown) into the seat provided in the lower half die 47. By continuing to produce a thrust action by means of the actuator 404a the second element 402 will contact against the first element 401 and the various elements 405-409 comprised in the upper part 41 and combined in a single block to which the half die 49 is fixed. At this point the element 2 is completely clamped between the two half dies 47, 49 in such a way that they confer on it, by means of a further cold forming operation, the shape shown in Figure 2b. As will be noted from observation of this latter figure, at the station 40 the element 2 is lowered, whilst the outer surface becomes more rounded; at the same time the two

cavities

21a, 22a become enlarged (Figure 2a) until they become the

cavities

21b, 22b shown in Figure 2b.

When the punch unit 41 is raised by the effect of the actuator 404a the pin 400, because of the spring 403 and the positive action of the actuator 404b, continues to maintain the element 2 in the lower die half 48; at this point the extraction bush 44 is raised by the actuator 45 to press the element 2 outwardly whereby to effect extraction from the lower die half 47.

At the end of the cold forming operation effected by station 40 the element 2 is located in the space between the two

units

41, 42 which comprise this station 40, supported by the extraction bush 44.

The

stations

50 and 60 shown respectively in Figures 5 and 6 are practically identical to the station 40 and for this reason will not be described in detail in the present discussion. For convenience of explanation, in Figures 5 and 6 the same elements have been given the same numerals substituting the numerals 5, 6 respectively for the reference numerals of Figure 4.

As can be seen from observation of both Figures 5 and 6 and Figures 2c and 2d the only differences from the station 40 lie in the different form of the

lower punches

53, 63 and a portion 59a, 69a of the respective upper half dies 59, 69. These differences in the punches and the dies give rise to the

cavities

21c, 22c (Figure 2c), 21d, 22d (Figure 2d) which are even deeper than the preceding cavities. It can also be noted that at

stations

50, 60 the outer surfaces of the element 2 are further rounded.

The deformation operations at the three

stations

40, 50, 60 have been effected gradually so as not to give rise to internal cracks or fractures in the material of which the element 2 is made.

At station 70 shearing of the central part 23 of the element 2 (Figure 2d) takes place.

This station 70 comprises an upper punch unit 71 and a lower die unit 72. In the lower die unit 72 there is an extraction pin 73 driven by an actuator 74 and a device 75 inserted in a suitable seat formed in a channel 700 which serves to retain the pad 76 which represents the waste from the shearing operation and derives from shearing of the central part 23 of the element 2 (Figure 2d). In particular, the device 75 comprises a ball 77 engaged by an anvil 78 biased by a spring 79. The ball 77 projects slightly into the channel 70 along which the expulsion pin 73 acts. The lower die unit 72 further has a die 701 for receiving the lower portion of the element 2.

In the upper punch unit 71 can be seen an extraction bush 703 which can be moved coaxially outside a shearing punch 702. The actuator 704a moves the punch 702 via the

elements

705, 706, 707, 708 and the punch, in turn, presses the element 2 in order to carry it into the seat provided in the die 701.

During its advancing stroke the upper punch 702 shears the pad 76 which is retained by the ball 77 of the device 75. The device 75 is very important because in its absence the pad 76 would be drawn back during the upward return phase of the shearing punch 702. At this point the actuator 704 causes the punch 702 to return back; the element 2 remains attached to it by the effect of the elasticity of the material of which it is made. In other words the punch 702 is designed in such a way that it forms a through hole 24 (Figure 2e) in the element 2 by shearing, in which hole this punch 702 engages with a force fit by the effect of the elasticity of the material with which the element 2 is made.

Once the element 2 has been extracted from the die 701 it remains to remove this element 2 from the punch 702 by means of a downward movement of the bush 703 moved by the actuator 704b via the three pins 709 (in Figure 7 only one of which is visible). As a final operation the expulsion of the pad 76 is effected which, as already mentioned, is retained by the ball 77 of the device 75. This expulsion is achieved by means of an upward movement of the expulsion punch 73 caused by the actuator 74.

At this point the cold working phases of the material are completed and the element 2 can be sent on to other machines which can perform possible finishing operations required by the specifications.

Claims

Apparatus (1) for producing a ball element (2) for a ball joint, the said ball element (2) being provided with a central through hole (24), the apparatus being characterised in that it comprises

a cutting station for producing substantially cylindrical metal starting workpieces;

at least one cold forming station (30, 40, 50, 60) for cold forming the said metal workpiece to round at least a portion of the outer surface of the said metal workpiece and create simultaneously pairs of cavities (21a, 22a; 21b, 22b; 21c, 22c; 21d, 22d) on the outer surface of the said metal workpiece;

a shearing station (70) at which a central part (23) of the said workpiece is punched out;

means for displacing the workpiece to and from the said cutting station, the said cold forming stations (30, 40, 50, 60) and the said shearing station (70); and

a control unit (10) for controlling the operations.
Apparatus (2) as claimed in Claim 1, in which there are at least three said cold forming stations (30, 40, 50, 60) and in which at the said cold forming stations (30, 40, 50, 60) and in relation to the passage from one station to the other, progressive rounding of at least one part of the outer surface of the said workpiece and progressive enlargement of the said pairs of cavities (21a, 22a, 21b, 22b, 21c, 22c, 21d, 22d) take place.
Apparatus (1) as claimed in Claim 2, in which the said at least one cold forming station (30, 40, 50, 60) is provided with at least one lower half die (35, 47, 57, 67).
Apparatus (1) as claimed in Claim 3, in which the said at least one cold forming station is provided with an extraction bush (44, 54, 64) driven by respective actuators (45, 55, 65) to extract the said workpiece from the said lower die half (35, 47, 57, 67), the said extraction bush (44, 54, 64) engaging with a pin (43, 53, 63) in a slidable manner.
Apparatus as claimed in Claim 1, in which the said shearing station (70) comprises a shearing punch (702) slidably engaged by an extraction bush (703).
Apparatus as claimed in Claim 1 or Claim 5, in which the said shearing station (70) includes means (75) operable to retain the waste pad (76) and means (73) which, suitably driven by an actuator (74), are operable to expel the said waste pad (76).
Apparatus as claimed in Claim 6, in which the said means (75) operable to retain the waste pad (76) comprise retaining means (77) projecting into a channel (700) into which the said waste pad (76) is thrust during the shearing operation, the said retaining means (77) being biased by resilient biasing means (79).