EP2210686A1

EP2210686A1 - Press for hot pressing billets and the like

Info

Publication number: EP2210686A1
Application number: EP10150080A
Authority: EP
Inventors: Domenico Caggioli
Original assignee: Mecolpress SpA
Current assignee: Mecolpress SpA
Priority date: 2009-01-21
Filing date: 2010-01-05
Publication date: 2010-07-28
Anticipated expiration: 2030-01-05
Also published as: ES2420586T3; EP2210686A8; EP2210686B1; ITMI20090056A1; IT1392795B1

Abstract

The present invention relates to a press (1) for hot pressing billets and the like, comprising a bottom forging die (3) rigidly coupled to the base (2) of the press and a base framework, through resilient supporting elements, and a bottom or base framework as well as a top forging die (4) associated with the press sledge (5).
On the bottom die (3) at least a movable punch element (11) for press forming the workpiece is provided.
The main feature of the invention is that the press further comprises driving means (13,14,16,20,21) for driving the movable punch (11), said driving means including two toggle levers (13,16) operating between the punch element (11) and a fixed point (17), a hydraulic cylinder (20,21) operating on the lever pivot pin for driving the punch element (11).

Description

BACKGROUND OF THE INVENTION

The present invention relates to a press for hot pressing billets and the like.
As is known, for hot pressing articles, usually made of a brass material, mechanical or hydraulic presses which comprise toolings allowing to provide, by using a contoured pattern in the press die or molds and suitable movable punches, a desired configuration or shape are conventionally used.
In actual practice, upon having introduced a heated material length, the pressed pieces, even including large depth borings, are achieved by the press punch assemblies, thereby achieving saving materials and a greatly reducing the press operating time.
Typically, the above mentioned toolings comprise one or more movable punch elements which are mounted, by resilient mounting support elements, on the bottom half-die or mold.
The top half-die, in turn, is directly fixed to the sledge or ram of the press.
As the press ram is downward driven, the top half-die, as it contacts the bottom half-die, presses the resilient system supporting the bottom half-die holding means and, in the meanwhile, through one or more crank levers or the like, causes all the punch elements to simultaneously penetrate into the material being pressed.
While the above operating method is satisfactory under several aspects, it, however, does not allow to individually control each punch element, both with respect to its penetrating stroke and to a possibility of properly differentiating the starting and end of stroke times.
In order to overcome the above mentioned problem, a prior approach provides to use a driving system with corresponding hydraulic cylinders directly arranged on each punch element; however, such approach, because of the required high force and operating speed, requires to use high power driving motors, and corresponding large displacement hydraulic pumps as well as large amounts of circulating oil.
Accordingly, because of the high inlet and outlet speed of the punch element with respect to the die, it is necessary to use large size and high cost mechanical detent elements and manual adjusting assemblies.

SUMMARY OF THE INVENTION

Accordingly, the aim of the present invention is to overcome the above mentioned problems, by providing a press for hot molding billets and the like, allowing to manage the driving of the punch elements in an adjustable time and with variable operating strokes between respective punch elements, without using large displacement hydraulic pumps.
Within the scope of the above mentioned aim, a main object of the invention is to provide such a press adapted to operate with large pressing forces, while facilitating the forming of the workpieces, to provide high quality end pressed products.
Another object of the present invention is to provide such a press which, owing to its specifically designed constructional features, is very reliable and safe in operation.
Yet another object of the present invention is to provide such a press for hot pressing or molding billets and the like, which can be easily made and which, moreover, is very competitive from a mere economic standpoint.
According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a press for hot pressing billets and the like, said press comprising a bottom press-forging die or mold rigidly coupled to the base of the equipment and to a basic frame, through resilient supporting elements, and to a top forging die, associated with the sledge of said press, on said bottom forging die being moreover provided at least a movable punch element for forming a workpiece, characterized in that said press further comprises driving means for driving at least a movable punch element, said driving means including two toggle levers operating between said punch element and a fixed point, said press further comprising a hydraulic cylinder operating at a pivot point of said toggle levers for driving said punch element.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more apparent hereinafter from the following detailed disclosure of a preferred, though not exclusive, embodiment of a press for hot pressing billets and the like, which is illustrated, by way of an indicative, but not limitative, example in the accompanying drawings, where:

Figure 1 is a schematic perspective view showing the press according to the present invention;
Figure 2 is a front elevation view of the press according to the present invention;
Figure 3 is a further side elevation view of the press according to the present invention;
Figure 4 shows a top plan view of the press according to the present invention;
Figure 5 shows a further cross-sectional view substantially taken along the section line V-V of figure 2;
Figure 6 shows a further cross-sectional view, substantially taken along the section line V-V of figure 2, of the inventive press including three punch elements;
Figure 7 is a further cross-sectional view showing the punch elements in a lowered or introduced position thereof;
Figure 8 is a schematic view showing the punch element at an opening position thereof; and
Figures 9 and 10 show a position transducer for controlling the operating strokes of hydraulic pistons controlling the punch elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the number references of the above mentioned figures, the press for hot pressing billets and the like according to the invention, which has been generally indicated by the reference number 1, comprises a bearing framework 2, which supports the operating equipment or tooling with a bottom mold or forging die 3 which is coupled with rigid supporting elements.
More specifically, the top forging die 4 is coupled to the ram or sledge 5 of the press, which is advantageously driven by hydraulic driving means.
At the lower mold or forging die of the press, a plurality of movable punch elements, generally indicated by the reference number 10 are provided.
The main feature of the invention is that the movable punch elements 10 comprise a punch member, indicated by the reference number 11, which is introduced to provide a forming or shaping operation on the billet 8, into the corresponding mold or die.
A further very important feature of the invention is that two toggle levers are herein provided, and, more specifically, a first toggle lever 13, pivoted to the movable carriage 14 supporting the punch member 11, and adapted to be driven with respect to the forging die.
The first toggle lever 13, in particular, is pivoted, at the other end portion thereof, to a fixed point of the punch bearing carriage support, coupled to the base of the bottom die bearing equipment, which is rigidly fixed to the framework 2.
To properly drive the movable carriage 14, a hydraulic cylinder 20, the piston stem 21 of which is coupled to the pivot point of the levers 16 and 13 is herein provided.
This assembly comprises the toggle levers and movable carriage and may be arranged both vertically and horizontally on its supporting base.
In this connection it should be apparent that the inventive press may comprise any desired number of punch elements, as shown, for example, in figures 5 and 6, which show press embodiments including four and three punch elements respectively.
In operation, the telescopically sliding movable carriage will support the punch element or member 11 to be driven for introducing it for engaging the pivot region of the levers and cylinder.
The pressing cylinder comprises, as is shown in figures 9 and 10, a first piston 30 coupled to the lever pivot stem 21, thereby allowing the punch element to be easily introduced into and withdrawn from the die.
Moreover, a second piston 35 projecting from a rear flange 36 for adjusting the piston stroke is herein provided.
More specifically, the adjustment of the full stroke of the punch element is performed by driving and locating the second piston 35 in the cylinder chamber directly through the electrohydraulic system, generally indicated by the reference number 40, which also allows to electronically detect the achieved position.
If the press equipment or tooling comprises two or more punch bearing assembly, then each said assembly will be an actually independent and autonomous operating arrangement.
Moreover, it is herein possible to manage or control in a separate manner the operation time, to facilitate the material extruding operation, while facilitating its displacement to points which could not be easily reached and to prevent undesirable urging or pressing forces from being applied to the other punch elements.
From the above disclosure it should be apparent that the invention fully achieves the intended aim and objects.
In particular, the fact is to be pointed out that the provision of a toggle lever system allows to greatly reduce the driving power, since the toggle arrangement provides the possibility of gradually multiplying the applied pressing force, while reducing the linear displacement speed or rate.
Thus, the forming of the workpiece will be greatly facilitated, since with a smaller penetration speed of the punch element into the material, the required effort or force will be correspondingly less.
Moreover, with the herein provided toggle lever system, as the linear driving speed or rate decreases, the penetrating force will correspondingly increase.
Thus, by suitably designing the size of the toggle levers, it is possible to achieve very high operating forces with small driving pressing efforts.
Thus, as stated, the invention fully achieves the intended aim and objects.
In particular, the fact is to be pointed out that the use of a mixed hydraulic and mechanical system, including the toggle lever arrangement and the hydraulic cylinder, allows to greatly improve the press operation, and to greatly reduce the required power.
The invention, as disclosed, is susceptible to several modifications and variations, all of which will come within the scope of the invention.
Moreover, all the constructional details can be replaced by other technically equivalent elements.
In practicing the invention, the used materials, provided that they are compatible to the intended use, as well as the contingent size and shapes, can be any, depending to requirements.

Claims

A press for hot pressing billets and the like, said press comprising a bottom press-forging die rigidly coupled to the base of the equipment and to a basic frame, through resilient supporting elements, and to a top forging-die, associated with the sledge of said press, on said bottom forging die being provided at least a movable punch element for forming the workpiece, characterized in that said press further comprises driving means for driving at least a movable punch element, said driving means including two toggle levers operating between said punch element and a fixed point, said press further comprising a hydraulic cylinder operating at a pivot point of said toggle levers for driving said punch element.
A press, according to claim 1,
characterized in that said press comprises a movable press carriage supporting, at an end portion thereof, at least a punch element and, at the other end portion thereof, being coupled to one of said toggle levers.
A press, according to claim 1,
characterized in that said press comprises a plurality of mutually independently driven punch elements.
A press, according to claim 1,
characterized in that said hydraulic cylinder comprises a first hydraulic cylinder piston coupled to a piston stem operating at said pivot point and a second piston projecting from a rear flange of said hydraulic cylinder for adjusting the operating stroke of said punch element.
A press, according to claim 1,
characterized in that the overall stroke of at least a said punch element is adjusted by driving and arranging the rear piston inside the hydraulic cylinder chamber.
A press, according to claim 1,
characterized in that said press comprises an electrohydraulic actuator adapted to operate as an absolute position transducer for controlling the stroke and locating of said rear piston.