WO2008095272A1

WO2008095272A1 - Closed die for forging irregular-shaped parts

Info

Publication number: WO2008095272A1
Application number: PCT/BR2008/000035
Authority: WO
Inventors: Luiz Fernando Timm; Sandro Luis Da Rosa; Adão Martins DA CUNHA
Original assignee: Dana Indústrias Ltda.
Priority date: 2007-02-06
Filing date: 2008-02-06
Publication date: 2008-08-14
Also published as: BRPI0701396B1; BRPI0701396A

Abstract

The present invention provides a closed die comprising two parts / the upper die (1A) and the lower die (1B), the complimentary shapes of the same are designed to provide the closed die with a configuration intended to form the desired three dimensional irregular part (P) and at the same time contain the flow of excess material (burr) during forging of the part.

Description

CLOSED DIE FOR FORGING IRREGUIAR-SHAPED PARTS FIELD OF THE INVENTION

The present invention refers in general to forging and in particular to hot forging with closed dies. BACKGROUND OF THE INVENTION

Forging with closed die is a mechanical manufacturing process in which a blank of metal is deformed by strong compressive forces to a desired geometrical shape provided by a closed die comprised of two parts (upper die and lower die). There are three types of forging - cold, warm and hot. The present invention is directed to hot forging.

The use of closed die in hot forging is known in the art. Document US 4,015,461, to Schober, discloses a closed die comprised of upper die and lower die that are pressed together during the forging operation to form a closed cavity in the shape of the finished work piece without a burr cannel in the interface between the upper die and the lower die. According to the disclosure of the cited patent, among the objects of the closed die described therein there are: To provide a die not requiring burr channel in the interface between the elements of the die (upper die and lower die) ;

To avoid the partial filling of the elements of die cavity, that is, that the flow of material is not reversed more than one time (first filling with material the cavity elements of upper die and after the cavity elements of upper die) ;

To assure that all the flow of material required is completed prior to the cooling of the material causing defects in the finished product; and others.

In view of the relevance of raw material in the cost of forged part, the optimization of the material consumed in forging is an important task to reduce the cost in a forging shop. As previously mentioned, the use of closed die is common in forging shops, however, as used nowadays the closed die is applicable uniquely to manufacturing of parts having regular geometry, for example, cylindrical parts for which the tools are obtained by turning process. For such parts, the definition of the shape of closed dies is base on a two- dimension profile that is revolved around an axis thus resulting in a revolution surface. In the state of the art, the concept of forging in closed die is not applied to parts having three-dimension profile having irregular contour. OBJECT OF THE INVENTION

In view of the above, the state of the art lacks the application of the concept of closed die to irregular parts having a profile in three dimensions (not only in a single plane) in the forging shops in general and, particularly, in the field of hot forging.

Thus, the present invention refers to a closed die comprising two parts, the upper die and the lower die, designed to contain the flow of excess material in forging (burr) during the process of forging irregular parts. SUMMARY OF THE INVENTION

According to the present invention it is provided a closed die comprising two parts, the upper die and the lower die, the complimentary shapes of the same are designed to provide the closed die with a configuration intended to form the desired irregular three-dimensional part and at the same time to contain the flow of excess material (burr) during forging of the part.

The object and advantage of the present invention will be apparent to those skilled in the art from the following description of the preferred embodiment when read in the light of the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of the closed die of present invention with the two parts of the die separated from one another and with the finished part in the interior thereof. Figure 2 is a cross-section view (in the direction of arrows II-II of Figure 1) of the closed die of present invention with the two parts of the closed die engaged to one another and the finished part in the interior thereof.

Figure 3 is a cross-section view (in the direction of arrows III-III of Figure 1) of the closed die of present invention with the two parts of the closed die engaged to one another and the finished part in the interior thereof. DETAILED DESCRIPTION

Now the closed die of the present invention will be briefly described with reference to the appended Figures which illustrate a transmission yoke as the forged part in the closed die of present invention, however it is to be noted that although the present invention is described and illustrated with reference to a transmission yoke it is not limited to that particular part, but on the other hand any part having irregular shape can be forged with the closed die constructed according to the concept revealed herein.

The application of the inventive concept of the present invention requires care in the phase of defining the design of the closed die, in the phase of constructing the tools (closed die) and also in the phase of forging the part in the press wherein it is manufactured. Below it described the care to be taken in order to obtain the forged part with this concept of tools.

During the design stage, more specifically, when defining the geometries of upper and lower dies, it is necessary to leave a suitable gap between the dies such that the same engage to one another during the forging operation. That engagement relies on a closing height of the dies in the press under which results said gap between the dies. In the machining phase, upon manufacturing the tools defined in the design, it is necessary to reproduce exactly the geometries of the dies that were defined in order not to occur problems in the engagement of the dies as previously mentioned. In the forging of a part of the present invention care is to be taken mainly as to the weight (size) of the catch (blank) to be forged with this design of closed die. If a larger catch is used, having weight above the one permitted, it may occur breakage of the dies due to excess material conformed within the same. On the other hand, a catch having the weight below the one specified may cause lack of material in the part that is being forged.

With reference to Figure 1, it is illustrated a closed die in general indicated by numeral 1, comprised of two parts, the upper die IA and the lower die IB, and the part to be forged P. In Figure 1 it represented as a part to be forged a transmission yoke. However, as previously mentioned, the present invention is not limited only to closed dies for forging transmission yokes. The present invention applies to any part of irregular shape having three-dimension profile (not only in a plane), such as, cross pieces, flanges, terminals and etc.

The main object of the design of closed die of the present invention is to contain the flow of excess material

(burr) through the escape area indicated by numeral 2 in Figures 2 and 3, during the forging operation of the irregular part. Upon using this concept of closed die it' is obtained an irregular part having three-dimension profile hot forged with minimum burr which was optimized through the escape area previously indicated by numeral 2. Upon flowing through this escape area that has a well limited region the material then finds serious limitations as to space that prevent the same from exiting the cavity where it is.

In order to attain the object of present invention the geometry of upper die IA and lower die IB is defined such as to provide greater control of the escape of material from within upper die IA and lower die IB, further to obtaining the full filling of the part to be forged. For that, for applications to parts having three-dimensional profile to be forged using the closed die of present invention the inside geometry of upper die IA and lower die IB is defined with the assistance of CAD/CAM systems available in the market. For the practice of the present invention the inside geometry of upper die IA and lower die IB needs to be duly modeled and later machined such that the upper die IA engages with an established small gap the lower die IB.

Claims

CIAIMS

1. Closed die for forging irregular-shaped parts, having two parts, the upper die and the lower die, characterized by comprising: Inner profile of upper die (IA) and inner profile of lower die (IB) configured in complimentary shapes of the irregular three-dimensional part (P) to forge; wherein

In the interface between the upper die (IA) and lower die (IB) it is provided an escape area (2) sized to minimize the burr and permit full filling of part (P) .

2. Closed die, according to claim I₁ characterized in that the configuration of inner profile of upper die (IA) and lower die (IB) is made with the assistance of CAD/CAM.

3. Closed die, according to claim 1, characterized in that the configuration of inner profile of upper die (IA) and lower die (IB) is modeled prior to machining when defining the design.