WO2008040709A1

WO2008040709A1 - Forging press

Info

Publication number: WO2008040709A1
Application number: PCT/EP2007/060404
Authority: WO
Inventors: Francesco Biasion
Original assignee: BIFRANGI SpA
Current assignee: BIFRANGI SpA
Priority date: 2006-10-05
Filing date: 2007-10-01
Publication date: 2008-04-10
Anticipated expiration: 2009-04-05
Also published as: ITVE20060060A1

Abstract

A forging press characterised in that its machine body is produced in separate parts (2, 4, 6) which in those regions subjected to mutual stresses during machine operation are maintained coupled together at toothed surfaces having their overall toothing plane parallel to the machine operative direction.

Description

FORGING PRESS

The present invention relates to a forging press, in particular a horizontal press.

Forging presses are known; they comprise a load-bearing structure or machine body of essentially annular parallelepiped shape with two shoulders connected together at one end by a striker portion and at the other end by a closure base. The two shoulders comprise facing holes for passage of a shaft with a cam which drives a ram to which punches are applied, to cooperate with dies applied to the striker portion for forging metal pieces carried at the softening temperature and interposed between the punches and dies.

More specifically, several dies, generally four, are applied to the striker portion of a forging press, an equal number of punches being applied to the ram to cooperate with the respective dies and determine progressive forming of the workpieces, which at each machine cycle are moved from one die to the next.

Taking account of the considerable stresses in play and the need to implement this forging in successive steps with several dies, the machine body of a horizontal press is generally constructed as a single steel block by casting. This places extensive limits on both the constructability and transportability of the machine body.

With regard to constructability, the dimensions of the machine body require very lengthy casting times and equipment of considerable dimensions such that only a few foundries in the world are able to produce machine bodies of adequate size for the production of even modest dimension workpieces. For example to form workpieces of weight less than 8 kg, which represents the maximum limit currently attainable, a machine body is necessary of weight more than 150 metric tons and with dimensions of more than 2 metres in height, about 3 metres in width and about 6 metres in length.

Moreover, to increase the workpiece dimensions, the press power has to be proportionally increased, resulting in a more than proportional increase in the problems which arise in achieving it. To remain within the preceding example, to form forged workpieces of weight less than 8 kg, a horizontal press is required of power slightly less than 2000 metric tons.

Again in relation to the formability of a horizontal forging press component, a monolithic machine body of those dimensions cannot necessarily be constructed in a selected type of steel, as the casting process limits the types of steel usable; consequently it is sometimes impossible to construct a machine body able to provide the particular performance required by the type of workpieces to be obtained and the stresses in play.

Apart from this, a machine body produced by casting uses a single type of steel, which does not enable different behaviours to be obtained on the basis of the stresses to which the various parts are subjected when in operation.

Finally, casting always introduces defects typical of the process, such as inclusions, blowholes, etc., leading to the need to over-dimension the machine body to achieve an acceptable degree of safety.

Again, in the case of fractures or structural yielding of the machine body, it has to be totally replaced, with production and installation costs equal to those of the original body.

With regard to transportability of the machine body from the production foundry to the factory of use, road traffic regulations and the actual equipment used for its transfer pose limits on the maximum dimensions of the machine body and hence on the performance which the forging press is able to provide.

This latter drawback has already found a solution in vertical presses, which are constructed in modular parts held together by tie bars. However these presses are much slower, as they enable only one workpiece to be forged at a time and are also much less precise and hence require the workpieces to be produced with a greater machining allowance.

In the light of this state of the art, the present invention confronts the problem of constructing forging presses which ensure greater rigidity to the machine body, even though of small dimensions.

This and further objects which will be apparent from the ensuing description are attained, according to the invention, by a forging press as described in claim 1 .

A preferred embodiment of the present invention is further clarified hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a schematic perspective view of the machine body of a horizontal forging press according to the invention' Figure 2 is an exploded perspective view thereof, Figure 3 is a side view thereof, and Figure 4 is a horizontal section therethrough on the line IV-IV of Figure 3.

As can be seen from the figures, the machine body of the forging press according to the invention consists essentially of an annular structure comprising two shoulders 2, disposed parallel to each other and joined together at one end by a closure base 4, at the other end by a striker portion 6 and in their middle region by a stiffening crosspiece 8. In the region in which each shoulder 2 is joined to the closure base 4, the shoulder presents a vertical slot 10 and the closure base presents a complementary rib 12. The shoulders and closure base are joined together by traditional screw systems, not shown in the drawings. In the region in which each shoulder 2 is joined to the striker portion 6, that inner surface of the shoulder involved in this connection presents a plurality of sawteeth 14 extending vertically, i.e. with their sharp edge vertical, and having their inclined flank facing the near end of the shoulder. Correspondingly the two end surfaces of the striker portion 6 present a plurality of sawteeth 16 cooperating with the teeth 14, i.e. having their sharp edge vertical and their inclined flank facing the closure base 4.

When in their assembled state the two shoulders 2 are maintained fixed to the striker portion 6 with the toothed surfaces 14 and 16 mutually engaged, by the presence of screws, not shown in the drawings. Each of the two shoulders 2 comprises a hole 18 coaxial to the hole in the other shoulder, to rotatably support a shaft provided with a cam for driving a ram towards and away from the striker portion 6. For reasons of representational simplicity, the shaft with cam and the ram, which are of traditional type, have not been illustrated in the drawings, neither have the punches applied to the ram and cooperating with the dies applied to the striker portion 6.

The aforegoing description with reference to a horizontal press also applies in the case of a vertical press.

From the aforegoing it is apparent that the machine body of the invention, both for a horizontal press and for a vertical press, is much more advantageous than the machine body of traditional forging presses, and in particular:

- it enables the machine body to be formed in separate parts,

- it enables these, if produced by casting, to be obtained in shorter times and with simpler and less bulky equipment,

- it enables the separate parts to be produced by forging and hence practically from any type of steel and with greater compactness and reliability characteristics, and hence with the facility to increase the machine operative power, - because of the greater power obtainable, larger-dimension workpieces can be produced. For example, on the basis of design data, using a horizontal press, workpieces weighing 20 kg can be produced with press powers of 4000 metric tons,

- the different separate components can be produced from different types of steel on the basis of the specific stresses to which they are subjected during operation,

- it simplifies workpiece production because of the simple shape of the individual components compared with the shape of the entire monoblock,

- it substantially facilitates the operations involved in transporting the disassembled machine body.

Claims

C L A I M S

1 . A forging press characterised in that its machine body is produced in separate parts (2, 4, 6) which in those regions subjected to mutual stresses during machine operation are maintained coupled together at toothed surfaces (16, 18) having their overall toothing plane parallel to the machine operative direction.

2. A forging press as claimed in claim 1 , characterised by being of horizontal type.

3. A forging press as claimed in claim 1 , characterised by being of vertical type.

4. A press as claimed in claim 1 , characterised in that the machine body has an annular structure with two shoulders (2) joined together at one end by a closure base (4) and at the other end by a striker portion (6), said toothed surfaces (16, 18) being located in the end surfaces of said striker portion (6) and in those internal lateral surface portions of said shoulders (2) in contact with said striker portion (6).

5. A press as claimed in claim 2, characterised in that the teeth of said toothed surfaces (16, 18) extend in a vertical direction.

6. A press as claimed in claim 1 , characterised in that said toothed surfaces (16, 18) comprise sawteeth, which in the shoulder (2) have their inclined surface facing the corresponding end of the shoulder, whereas in the striker portion (6) they have their inclined surface facing the closure base (4).

7. A press as claimed in claim 1 , characterised in that those parts (2, 6) of the machine body provided with the toothed surfaces (16, 18) are maintained coupled together by screws having their axis substantially perpendicular to the overall toothing plane.

8. A press as claimed in claim 1 , characterised in that said machine body is produced in separate parts (2, 4, 6) obtained by casting.

9. A press as claimed in claim 1 , characterised in that said machine body is produced in separate parts (2, 4, 6) obtained at least partly by forging.