Technical Field

The invention relates to a device for pressing large forgings, especially centre pieces of built-up crankshafts for large marine engines.

Background Art

A pertinent device is hitherto solved in different ways. .

A special device TR (Theodore Rut) according to the patent CS 256 356 is used, which consists of three working instruments, particularly of an upper tool and two jaws. The upper tool moves vertically, while the jaws perform simultaneously the movement along a circular arc towards the axis of the device. A centre piece of a built-up crankshaft is manufactured by a simultaneous movement of the top tool downwards and the jaws against each other.

A disadvantage of this device consists in its complexity and the time-consuming installation on the press prior to forging. Its use is thus appropriate only for large series of forgings of centre pieces having the same size and shape. Another device according to the patent JP 6000575 of the company KOBE STEEL LTD is used, whose distinguishing feature is that a triangular pyramidal punch, which is guided along both sides, is pressed into a pressing device, which consists of a forging die with molding conical surfaces of arms and an anvil on a conical bottom thereof for creating a pin.

Alternatively, a blank can be first crammed into the die and then the punch can be pressed in.

After forging the anvil for shaping the pin into the molding edges, the blank is removed from the press device and the arms are flattened.

A disadvantage of this device is a lengthy production of the forging and the need of more operations in combination with the volitional forging.

Another disadvantage consists also in that the manufacture of the longitudinal shaped blank requires large machining allowances, which is in turn brings about a low utilization of the material and the production is slow.

Summary of the Invention

Said shortcomings of the prior art have been eliminated by the present invention in that a device for pressing large forgings has been developed, which device includes an upper die, provided with an upper tool and a lower tool for the accommodation of a workpiece. The upper die is provided with a shedder.

The upper die is provided with the upper tool containing a blade plate, on which the blade is accommodated.

The blade plate is mounted on the upper die by means of a lifting eye and a hinge pin, both located on the upper die and also on the blade plate.

The blade is on each of its narrower sides provided with a groove.

Within the grooves, guide pins are movably accommodated, on which a guide element of the blade is movably positioned.

The lower tool is accommodated on a footplate by means of blocks (cubes).

The lower tool comprises an outer socket, two internal broader components situated against each other and two internal narrower components situated against each other.

Each internal narrower component is fitted with a supporting plate.

The shedder is preferably formed by two or more roller elements .

The guide element consists advantageously of two narrower plates and two broader plates that are mutually firmly connected and axially symmetrical for creeping the upper part of the forging. The footplate has preferably the shape of a shouldered circular plate where the shoulder has a smaller diameter than the inner diameter of the outer socket, and circumferentially the footplate comprises at least three sloped plates for centering the outer socket into the vertical axis.

The broader internal components and narrower internal components of the lower tool are preferably divided into always two and two components which are axially symmetrical and accommodated in the outer socket.

The outer surfaces of the broader internal components and inner narrower components of the lower tool, as well as the inner surface of the outer socket, have preferably a conical shape, and the surfaces form an angle γ in respect to the vertical axis.

The inner surfaces of the internal broader components and inner narrower components of the lower tool are preferably parallel with the vertical axis.

Internal broader components and narrower internal components of the lower tool have preferably at the bottom part a sloped surface, the two components opposite one another have an acute angle a and the other two components opposite one another have an acute angle β.

The blade is preferably provided with a bottom surface, rounded with a first radius Ri .

The guide element is preferably provided with a bottom surface, rounded with a second radius R. The blocks are preferably arranged in a number of at least three or more.

The device for pressing large forgings thus contains the upper die, provided with the hinge pin and shedder.

On the upper die, the upper tool is attached via the lifting eye, consisting of a plate, provided with hinge pins. The blade is accommodated on the plate.

The blade is equipped with a movably positioned guide element via a pilot pin, which is movable in a groove in the blade.

The device further includes a supporting plate with sloped plates, on which the lower tool in located by means of the blocks (cubes) (equal to at least three) .

The lower tool comprises an outer socket, two internal broader components opposite one another and two inner narrower components opposite one another.

Each internal narrower component is fitted with a supporting plate.

The advantage of the invention consists in that it allows the production of forgings of centre pieces, which follow the contours of the shapes of the finish tooled centre piece with uniform material allowances, the shoulders having parallel surfaces in the longitudinal direction, without bevels. It is also advantageous that the two opposite inner parts of the matrix, alongside of which the narrower blade wall is sliding, are preferably composed of two parts and the inner active part is replaceable.

It is also advantageous that the blade and guide element are connected by means of pins which move during the deformation in the grooves on the side walls of the blade, and by the blade handling the guide element remains always on the blade.

Another advantage of using this forming tool consists in that it allows the production of centre pieces in a die on conventional hydraulic presses destined for an open die forging .

The advantage consists also in that it is not necessary to equip the forming aggregate with a hydraulic or electric or complex mechanical ejector.

Another advantage of this invention consists in that the centre pieces have a continuous grain flow, namely in the pin parallel with the axis of the pin and on the arms parallel with the vertical axis of the arms with a continuous transition between the pin and strokes.

Compared to a conventional method of producing this type of centre pieces, it is not necessary to use the time-consuming and energy-intensive production of the input blank and the particular centre piece. Brief Description of the Drawings

The invention will be further explained in detail by means of examples of its preferred embodiments, the description of which will be given with regard to the attached drawings, where

Figure la and Figure lb show respectively a front and top plan view in a broken-out section of the device prior to pressing,

Figure 2a and Figure 2b show respectively a front and top plan view in a broken-out section of the device after the pressing,

Figure 3a and Figure 3b show respectively a front and top plan view in a broken-out section of the device after the release and before the removing the workpiece of the centre piece from the die.

Detailed Description of the Invention

An exemplary embodiment of the device for molding large forgings, especially centre pieces of built-up crankshafts for large marine engines according to the present invention is illustrated in the attached drawings. As shown particularly in Figure la and Figure lb, the device in question comprises an upper die 5 with a shedder 1, an upper tool 2, a lower tool 3 and a footplate 4.

In the upper die _5, which is attached on a press ram, the shedder 1 is built in, which is used for a so-called stripping .

After the forging, the shedder 1 allows by means of additional stop blocks (stops) 1_8 ^anc * the footplate _4 the release of broader inner parts 6 and narrower inner parts 7_ internal parts of the lower tool _3.

In an exemplary embodiment the shedder 1 consists of two or more rollers, built into the upper die 5, and the shedder 1 promotes with the help of additional stop blocks 1_8 and the footplate 4_ the removal of blocks 17, and the movement of the upper die _5 to its lower position.

The upper tool 2_ is attached to the upper die _5 by means of lifting eyes 8_ and hinge pins _9. The upper tooll_0 consists of a plate 1_0 of a blade 1_1, the blade 1_1 and a guide element 12.

The plate 10 of the blade 11 is fixed to the blade 11 at its end.

The blade 1_1 has on its side narrower walls a groove 13, which allows a movable connection of the blade 1_1 and the guide element 12 via the pilot pins 1 . The blade 11_ is preferably provided with a bottom surface, rounded with a first radius Ri.

The guide element 12 is used to guide the blade _11 into the lower tool 3 and to maintain the vertical position of the blade 11 when pressing.

The guide element 12_ is preferably provided with a bottom surface, rounded with a second radius R.

The guide element 1_2 consists of two narrower plates and two broader plates that are fixed to each other and axially symmetric.

The guide element 1_2 allows a creeping of the upper part of the forging 19.

The lower tool 3 or the matrix comprises an outer socket 15_, two broader inner parts 6, two inner narrower parts 1_ and two supporting plates 16.

The inner broader parts 6 and the inner narrower parts 1_ of the lower tool 3 are preferably divided into two and two parts, which are axially symmetrical, and which are supported in the outer socket 15.

The outer surfaces of the broader inner parts 6 and the inner narrower lower parts 7_ of the lower tool _3 as well as the inner surface of the outer socket _15 are preferably of a conical shape, thus the surfaces forming an acute angle with respect to the vertical axis. The inner surfaces of the inner broader parts 6 and the inner narrower parts 1_ of the bottom tool 3 are parallel with the vertical axis and preferably without bevels.

The inner broader parts 6 and the inner narrower parts 1_ of the bottom tool 3 have preferably a beveled surface 2JL in the bottom part thereof, and two parts placed against each other being under an acute angle a and the other two parts placed against each other being under an acute angle ]3.

The narrower inner parts 1_ of the lower tool 3 are provided inside with the supporting plate 16.

The supporting plate 16 serves to a protection of the inner narrower part 1_ from a deterioration by virtue of the blade 1_1, which during the pressing slides upon it and wears it. Thus, it is sufficient to replace only the supporting plate 16 and not the entire inner narrower part which is faster and cheaper.

Thus, the upper tool 2 is formed by the plate 10 of the blade 1_1, which is attached to the upper die 5. The plate 1_0 of the blade 1_1 is fixed to the blade 1_1 and the blade 1_1 is movably connected by means of the pilot pins 1_4 with the guide element 12.

The lower tool _3 is formed by the outer socket 15, in which two inner broader parts 6 of the lower tool 3_ facing each other and two inner narrower parts 1_ of the lower tool _3 facing each other are supported.

The inner narrower parts 1_ of the lower tool 3 are provided inside with the supporting plate 16. The outer socket 1_5 is supported on the footplate 4 on blocks 17.

The footplate _4 has a shape of a circular plate, where the shoulder has a smaller diameter than the inner diameter of the outer socket 1_5, and the perimeter has at least three sloped plates 2_2 for centering the outer socket 1_5 to the vertical axis.

The device function is evident from the illustration in the Figure 2a and Figure 2b, where the distinction between the Figure la and Figure lb at the end of the molding process is shown.

The upper tool 2_ is hung on the upper die _5 in the axis with the lower tool 3_.

Ά movement of the upper die _5 allows to position the guide element _12 upon the inner narrower part 1_ ^an< consequently the lower face of the plate 1_0 of the blade 1_1 upon the guide element 1_2, which enables the manufacture of the forging 1_9 of the centre piece from the respective blank 20.

Fig. 3a and 3b illustrate the course of action of the shedder 1 before and after the release of the inner broader parts 6 and the inner narrower 7_ parts of the lower tool 3.

The stop block 1_8, positioned on the outer socket 15, allows the release of the inner broader parts 6 and the inner narrower parts T_ of the lower tool _3 by the movement of the upper die 5_ into the lower position by means of the shedder 1 after the removal of the blocks 17. The outer socket 15 is located on the footplate 4_ and it is supported by blocks 1_7, the socket being centered to the axis of the press.

The pulling of the forging 1_9 of the centre piece from the lower tool _3 is facilitated by the stop blocks 1_8, which are during the release of the inner broader parts 6 and the inner narrower parts 7 of the lower tool 3 located on the outer socket L5, under the rollers of the shedder 1, which is in turn located in the upper die 5_ of the press, and at least three or more blocks 1_7 are removed.

By means of a movement of the upper die 5_ to the lower position, the inner broader parts 6 and the inner narrower parts °f the bottom tool 3 are released.

The invented device and the relevant tools serve mainly for the production of the forgings 1_9 of the center pieces of the crankshafts.

Industrial Applicability

The device according to the present invention can be used especially for the production of the center pieces of the semi-built-up crankshafts. List of reference sings

1 - shedder

2 - upper tool

3 - lower tool

4 - footplate

5 - upper die

6 - broader inner parts

7 - narrower inner parts

8 - lifting eye

9 - hinge pin

10 - plate 10 of the blade 11

11 - blade

12 - guide element

13 - groove

14 - pilot pin

15 - outer socket

16 - supporting plate 16 of the narrower inner parts 7

17 - block

18 - stop block

19 - forging 19 of the centre piece

20 - blank

21 - beveled surface

22 - sloped plate

Rx - first radius R - second radius - angle a of the bottom beveled surface 21 of the narrower inner parts 7 with respect to the vertical axis β - angle β of the bottom beveled surface 21 of the broader inner parts 6 with respect to the vertical axis

Y - angle γ of the outer surface of the broader inner parts 6 and narrower inner parts 7 and the inner surface of the socket 15 with respect to the vertical axis