EP2370216B1

EP2370216B1 - Method and apparatus for hot press working metal pieces with one or more cavities

Info

Publication number: EP2370216B1
Application number: EP09796440.7A
Authority: EP
Inventors: Giuliano Baglioni
Original assignee: Automazioni Industriali Srl
Current assignee: Automazioni Industriali Srl
Priority date: 2008-12-05
Filing date: 2009-11-23
Publication date: 2018-08-29
Anticipated expiration: 2029-11-23
Also published as: EP2370216A1; ITMI20082156A1; WO2010064103A1; IT1392472B1

Description

FIELD OF THE INVENTION

The present invention relates to a method and to a press for hot billet press forging, said billets being made of metallic material, such as steel, brass or bronze.
More in detail, the invention relates to a method and to a press for hot forging metallic pieces having one or more cavities, such as T-connectors for pipes.

BACKGROUND ART

Metallic pieces of the aforesaid type can be produced by plastic deformation of a metallic billet in vertical presses.
Prior art hot forging presses are generally composed of a closable mould formed of an upper half-mould and a lower half-mould.
The two half-moulds, in their closed position, exert a force on a heated metallic billet placed therebetween, at times causing a part of plastic deformation, or rather predeformation, thereof.
At least one of the two half-moulds moves vertically guided along a plurality of guides.
The upper half-mould is usually operated by a connecting rod actuator, while the lower half-mould is instead fixed at the base of the press to a cushion which can, for example, be pneumatic or hydraulic.
The vertical movement of the upper half-mould, determined by the connecting rod actuator, allows the mould to close.
Consequently, the billet is constrained inside a predetermined volume, determined by the mould in closed position, having the shape of the piece to be produced.
Production of the cavities of the pieces takes place through one or more moving pins which can be placed in an engagement with the metallic billet, during the steps in which the half-moulds move towards each other to the closed position.
The pins are inserted inside the body of the billet to determine further deformation thereof inside the mould.
In fact, the two half-moulds are generally provided with guides, appropriately positioned, to allow passage of the pins and thus make it possible to reach the position of engagement with the billet.
The production of pieces comprising several parts, and therefore a corresponding plurality of cavities, makes it necessary to have a corresponding number of moving pins.
In prior art vertical forging presses the pins are generally movable in a direction perpendicular with respect to the direction of movement of the half-moulds.
In other words, the moving upper half-mould is moved along the guides in vertical direction until coming into contact with the lower half-mould, usually fixed and positioned at the base of the press, and the pins can be positioned on a horizontal plane corresponding to the one in which joining of the two half-moulds takes place.
Movement of the pins is usually generated by converting the vertical motion of the half-mould, operated by a corresponding connecting rod actuator, through complex kinematic chains.
In this type of machines the movement of the pins is determined by the vertical motion of the press and besides suffering from problems linked to the complexity of the kinematic mechanisms for connection and motion conversion, this determines the need for another complex system to control the pins.
In fact, the pins are moved by the connecting rod actuator through complex linkages which either do not allow control thereof in terms of movement, speed and force, or make it excessively complex and expensive.
Other prior art forging presses for metallic billets provide for the use of a hydraulic actuator to close the half-moulds, moving half-mould toward the fixed half-mould in the lower part of the press, and a hydraulic actuator for every single pin, to allow direct and independent operation thereof.
EP1013357 , forming the basis for the preamble of claims 1 and 6, relates to an apparatus and a method for forging metallic pieces such as mechanical members, piping, valves and fittings. The production of these pieces is carried out using a forging die comprising an upper die member, a lower die member and three pins that can be inserted inside the die and are controlled independently.
Each pin is constrained to a piston of a hydraulic actuator, intended to control the movement of the pin by means of the passage of oil under pressure in two oil chambers. The force and velocity of the piston of the hydraulic actuator is controlled using an electronic control device which sends a signal to a pressure control valve and an outflow valve.
British patent GB 1197470 describes a method and a press for cold forming metallic pieces, for example in the shape of a T, from a solid metal billet.
The press includes a mould, formed of two separable parts, for plastic deformation of the billet.
The upper mould is operated by a hydraulic actuator.
The ends of the two parts of the mould that come into contact are appropriately, correspondingly tapered in order to form through holes to reach the billet from the outside, following the mould closure.
The holes are placed in correspondence with the cavities of the piece to be produced.
Each hole is adapted to accommodate a moving bushing, inside which, in turn, a pin slides.
Each pin can thus come into contact with the billet and impart a further force thereto which allows the desired plastic deformation in the piece to form the cavities to be achieved.
Each single pin is moved by a hydraulic actuator and further actuators, of the same type, are provided to lock each bushing.
Although the embodiment described above allows movement of the single pins, it does not allow their movements to be controlled with regard to extension, operating times, speed and so forth, so that in practice the pins are operated hydraulically instead of being operated conventionally with linkages associated with the closing movement of the half-mould.
Finally, in the state of the art there is no document that teaches or suggests controlling the movements of the moving components of the press according to the piece to be obtained, in order to optimize the production thereof. In other words, to date this is based solely on the experience and sensibility of operators, and on excessive power, to achieve the above.

OBJECT OF THE INVENTION

This being stated, it is now an object of the present invention to provide a method and a press for hot forging metallic pieces having one or more cavities which overcome the disadvantages of the prior art and which in particular allow independent control of the movements of the pins and of the moving half-mould, the control being carried out precisely and in accordance with the final piece to be produced.
A further object of the present invention is to supply a method and a press for hot forging metallic pieces provided with an easily automated control system, optionally also by software.

SUMMARY OF THE INVENTION

These and other objects are achieved through a method for producing metallic pieces having one or more cavities, by billet press forging, according to claim 1, wherein each single billet is placed in a closable mould and one or more pins are inserted into the body of the billet to deform it according to the mould.
The inserting movement of every single pin is controlled in its travel length, speed and feed force and in operating times, individually and coordinately with the movement of one or more pins and with the mould closing movement, according to the final piece configuration.
In accordance with a second aspect of the present invention, there is described a press for forging metallic pieces having one or more cavities, according to claim 6, comprising a closable mould for deforming at least one metallic billet.
The mould is formed by at least one moving half-mould, translatable vertically along a plurality of guides towards a second half-mould, preferably fixed. The press comprises, moreover, at least one pin insertable, at least partially, in said at least one first moving half-mould and said second half-mould, to reach an engagement position with said billet.
Said at least one pin is operated individually through an independent controlled axis.
By controlling each axis independently, the corresponding pin is operated in the desired manner according to the piece to be produced.
Moreover, during the forging steps, detection of the working parameters of the controlled axes, by appropriate means, allows immediate evaluation of undesirable malfunctions.
According to the present description, the term "controlled axis" is intended as the measurement and control, for example through a computer, of a given movement of the press performed through a motor, so that it is possible to position the moved element precisely in a random point of its available travel. The term "closed loop controlled axis" is also used to indicate that each position of the moved element is acquired and verified through a position transducer, for example an encoder.
In the present invention, moreover, control is not limited to positioning the moving element, but is also extended to the movement speed and the force exerted. Moreover, control of the movement of a moving element, in the present case the half-mould and the pins, is performed in one-to-one relation with controls of the other moving elements, as stated as a function of the piece to be produced.
Advantageously, the absence of kinematic control mechanisms of the pins allows reduction of wear of mechanical parts with consequent decrease of the probability of breakages occurring.
Moreover, by operating the pins independently by means of controlled axes, the control precision in terms of travel, speed, force transmitted and operating times can be improved.
The presence of a controlled axis for every single pin allows this control to be produced automatically and inexpensively, also by software.
Improved possibilities of independent control of the single controlled axes of the pins ensure greater quality of the finish of the piece.

BRIEF DESCRIPTION OF THE FIGURES

These and other advantages will be apparent from the description below and from the accompanying drawings, indicated herein by way of non-limiting example, wherein:

Fig. 1 is a front view of a press according to the present invention;
Fig. 2 is a plan view of the press according to section A-A of Fig. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENT INVENTION

With reference to Fig. 1, the vertical press for hot forging metallic pieces equipped with one or more cavities according to the present invention, in its preferred embodiment illustrated herein, comprises a fixed surface 1, positioned at the base of the press, a reaction surface 3, and a moving surface 2 translatable vertically along four guides 5.
The reaction surface 3 is locked at the upper end of the guides 5 while the fixed surface 1 is positioned at the base of these guides.
The guides 5 pass through the moving surface 2 which is vertically translatable between the reaction surface 3 and the fixed surface 1.
The fixed surface 1, the moving surface, 2 and the reaction surface 3 preferably have the same base shape, for example square or rectangular, and the guides 5 are positioned at the vertices of the base figure (Fig. 2). With reference to Fig. 1, a motor 10, adapted to move vertically the moving surface 2, is mounted, for example, above the reaction surface 3.
The motor 10 is preferably of the electric and controlled type.
In a possible embodiment of the present invention, the motor 10 is of the "Direct Drive" type.
The screw 11, operated by the motor 10, causes the translation of the moving surface 2 by means of the nut 12.
Appropriate means are placed on the moving surface 2, corresponding with each guide 5, to lock the moving surface 2 in the desired position along the guides 5.
The plate 14 constrained to the moving surface 2, translatable vertically therewith, is arranged to house different types of moulds (not shown in the figures).
The mould, not shown, is formed by a first half-mould mounted on the plate 14 of the moving surface 2.
The first half-mould is vertically translatable along the guides 5 towards a second fixed half-mould, positioned on the base surface 1.
When the two half-moulds are in contact, the mould is in closed position and causes deformation of the metallic billet, placed therebetween.
The metallic billet, necessary to produce the piece, is placed in the second fixed half-mould standing by for vertical translation of the moving half-mould 2 preferably operated by the motor 10.
Deformation of the billet takes place through the force exerted by the mould, together with the action of a plurality of pins which come into controlled contact with the metallic billet
In particular, in the production of metallic pieces, the cavities provided are produced by means of pins.
In fact, as can be seen with particular reference to Fig. 2, at the fixed surface 1, four motors 15, preferably of electric type, are provided, each controlled independently, for movement of four corresponding carriages 16.
A pin, not shown, is mounted on each of the carriages 16, to allow controlled deformation of the metallic billet.
Every single pin is controlled independently from the others through the corresponding electric motor 15, and is translatable at the fixed surface 1 in a direction perpendicular to the direction of movement of the moving surface 2. In particular, in a possible embodiment of the present invention, the four motors 15 for movement and independent control of the carriages 16 and of the corresponding pins are of the "Direct Drive" type.
Guides are appropriately placed on the fixed surface 1 and on the lower and upper half-moulds to allow passage of the pins and make it possible to reach the contact position with the billet, even when the mould is in closed position, i.e. when the two half-moulds are in contact.
In the press of the present invention, the pins are easily controllable in terms of travel, speed, feed speed and operating times, as each of them is operated by its own controlled axis, preferably an electric motor 15 and as no mechanical stops are used.
In particular, the use of "direct drive" motors 15 allows high performances to be achieved in terms of dynamics of movement and precision of movement of every controlled axis.
Moreover, motors of this type allow small movements of the controlled axes of the press to be performed and, simultaneously, very large forces to be imparted.
It must be noted that the pins can be controlled independently, but still coordinated with one another and with the moving half-mould, also with respect to the vertical movement of the moving surface 2 which, as stated, is operated by a controlled axis, preferably an electric motor 10.
For this reason, the pins can be positioned in contact with the metallic billet before the mould is closed, and by operating two opposite pins simultaneously the billet can be maintained in a raised position with respect to the fixed half-mould and to the fixed surface 1, standing by for lowering of the moving half-mould.
The sequence with which the pins are positioned in contact with the metallic billet is determined by the shape of the piece to be produced, allowing controlled deformation of the material according to a predetermined sequence.
Although specific reference has been made to a configuration in which the electric motors 15 and the corresponding pins are placed on surfaces staggered from one another by an angle of 90 degrees, other positions corresponding to the fixed surface 1, according to different orientations and relative angles, can be adopted without departing from the scope of the present invention as defined in the appended claims. The method according to the present invention for producing metallic pieces having one or more cavities, by billet press forging, will now be described. The metallic billet is placed in a closable mould and one or more pins are positioned in contact with the body of the billet to determine a further deformation thereof.
The present method comprises independent control of the inserting movement of every single pin in terms of its length of travel, speed and feed speed and of operating times.
In fact, each pin is operated by a dedicated motor preferably of electric type and their operating sequence is predetermined according to the shape of the piece to be produced.
Activation of electrical type also allows the pins to be controlled automatically, also by software, by controlling the working parameters of every single electric motor.
During the forging operations it is also possible to analyze and verify the correct development of the deformation process of the metallic billet inside the mould following contact with the pins.
In fact, by detecting and analyzing the working parameters of every single controlled axis, which activates the corresponding pin, any abnormalities of the deformation process of the material can be detected immediately, also automatically by software.
Detection of the working parameters of every single controlled axis, for example of the current spectrum in the case of electric motor, is performed by suitable detection means.
An unexpected variation of the current profile can be caused, for example, by breakage of the pin or by modifications of the state and of the characteristics of the material being deformed.
The current spectrum of each controlled axis during a forging operation with unsatisfactory results in terms of finished piece can be easily compared to the current spectrum in subsequent forging operations to detect process abnormalities.
This results in greater control on the quality of the pieces produced, with the possibility of immediately detecting malfunctioning and interrupting the process without invalidating subsequent forging operations.

Claims

Method for producing metallic pieces having one or more cavities, by billet press forging, wherein every single billet is placed in a closeable mould and one or more pins are introduced into the billet body to deform according to the mould, wherein the inserting movement of one or more pins is controlled in its travel length, speed and feed force and in operating times, individually and coordinately with the movement of one or more other pins and the mould closing movement, the control being carried out according to the final piece configuration, characterized in that every single pin is activated by an independent controlled closed - loop axis driven by an electric motor, by means of a position transducer.
Method according to claim 1, characterized in that the mould closing movement is controlled in its travel length, speed and feed force and in operating times, coordinately with the movement of said one or more pins.
Method according to claim 1, characterized in that the working parameters of every independent controlled axis are used for controlling said pin.
Method according to claim 3, characterized by detecting the working parameters of said controlled axis and using the same for controlling the normal execution of the press operations.
Method according to claim 3 or 4, characterized in that the working parameters of every independent controlled axis comprise the current spectrum of the electric motor.
Forging press for metallic pieces having one or more cavities, comprising a closable mould for deforming a metallic billet, one or more pins insertable, at least partially, in said closeable mould to reach an engagement position with said billet and cooperate to its plastic deformation, characterized in that every single pin is individually activable by an independent controlled closed-loop axis driven by an electric motor, by means of a position transducer.
Press according to claim 6, characterized in that it comprises a further axis of controlled type for closing said closeable mould.
Press according to claim 6 or 7, characterized in that it comprises means for controlling working parameters of every single independent controlled axis.
Press according to one of the claims 6 - 8, characterized in that it comprises means for detecting working parameters of every single independent controlled axis, during the moulding operations.
Press according to claim 8 or 9, characterized in that the working parameters of every independent controlled axis comprise the current spectrum of the electric motor.