EP0144981B1 - Method and device for forging crankshafts onto presses - Google Patents

Description

The invention relates to a device for forging crankshafts consisting of a base frame and a head piece arranged above this base frame and movable to and fro in the direction of this frame, wherein two mutually coupled movable tool holders are arranged in the space between the head piece and the base frame, which are arranged on the head piece are guided perpendicularly or obliquely to its direction of movement and which are coupled to the underframe with a parallelogram guide consisting of articulated levers, tools serving for the design of the crank cheek, bearing journal and crankpin fastening being fastened in the tool holders.

From GB-A-1 207 236 a device for forging non-coaxial workpieces, in particular crankshafts, is already known, in which a pair of dies which can be moved relative to one another in the pressing direction is provided, in which a rod section is gripped so that its axis is at an angle to the pressing direction. When the matrices approach each other, the rod section is compressed, while its central part is laterally displaced. This creates a crank arm with two associated pins. The crankshaft is forged by repeating these operations after the workpiece has been rotated accordingly. Because of the angular position of the blank, not enough material can be accumulated during upsetting to be able to form it into a long crank arm, so that the device for forging long-stroke crankshafts cannot be used.

For forging crankshafts on presses, it is known from DE-C-1 301 297 and DE-C-1 523 280 to clamp a heated rod section to be forged at two points spaced apart from one another and between the clamping points To compress part of the rod section in the axial direction of the rod, a bend and displacement being achieved transversely to the axial direction at the same time. At the beginning of the working stroke, the upsetting speed is greater than the bending speed, at the end of the working stroke, however, the upsetting speed is less than the displacement speed.

in welcher
N_P - die Presskraft
α - den Neigungswinkel der Gelenkhebel und
µ - den Reibungskoeffizienten zwischen den gleitend gelagerten Teilen der Vorrichtung bedeutet.It is also known to use devices for forging crankshafts by simultaneously upsetting and bending a rod, as are known from DE-C-2 823 799 and EP-A-0 003 139. These devices, which can be installed in forging presses, have a base frame with a head piece arranged above and movable back and forth in the direction of the base frame, two in the space between the head piece and the base frame Pairs of coupled movable tool holders are arranged, which are guided on the head piece perpendicularly or obliquely to its direction of movement and which are coupled to the underframe with the aid of a parallelogram guide consisting of articulated levers, tools serving for the design of the crank cheek, bearing journal and crank pin fastening being fastened. Between the end faces of these tools, a bending tool is rigidly attached to the base frame, with the anvil associated with it and rigidly attached to the headpiece being arranged on the headpiece. During the working stroke, the vertical movement of the head piece with the articulated levers is converted into movements of the divided tools and their holders running transversely to this head piece movement. They approach each other, the rod section located between the end faces of the divided tools being compressed. The size of the compressive force that can be achieved in such a device can be approximately calculated on the basis of the following equation:

${\text{P}}_{\text{h1}}{\text{= 0.5 N}}_{\text{P}}\text{(ctg α-µ)}$

in which
N _P - the pressing force
α - the angle of inclination of the articulated levers and
µ - means the coefficient of friction between the sliding parts of the device.

The compressed material is simultaneously bent in the direction of the anvil by the bending tool. During the working stroke, the rate of bending increases in proportion to the rate of upsetting as the bending progressively displaces the crank pin material with respect to the adjacent journal material transforms. In the final phase of the working stroke, both crank cheeks are formed.

The known devices are not suitable for forging long-stroke crankshafts, especially for high-performance ship engines, since the ratio of the length of the rod section to be compressed between the end faces of the upsetting tools to the diameter of this rod should have large values. The length of this section depends on the volume of the material required for forming the entire crank stroke (its two crank cheeks and the crank pin). There is therefore a risk of exceeding the permissible degree of slenderness during upsetting. Such an overshoot can cause an incorrect shape of the crank webs and in particular an irregular metal fiber course in the crankshaft.

The currently largest forging presses have a pressing force of approx. 80 to 120 MN. Monoblock crankshafts with a maximum stroke of approximately 1200 mm can be forged on such presses using the methods mentioned above. This limitation results from the required pressing force as well as from the space available between the ram and the table, as well as between the columns of the press. The largest crankshafts of heavy marine engines, on the other hand, have a stroke of up to 2950 mm. For the time being, there is no possibility of forging monoblock crankshafts with a stroke of more than 1200 mm. The long-stroke crankshafts mentioned above are therefore manufactured as built or semi-built shafts, the parts of which are connected by shrink-fitting.

The monoblock crankshafts have the advantage in comparison with half-built and built shafts that because of their smaller size, smaller and lighter engines can be built. For large marine diesel engines, half-built crankshafts have therefore been replaced by shafts in which individual crank bends forged with half-long journals are combined with one another by welding. However, welding is very time-consuming and complex, requires very precise control of the weld seam, etc.

The object on which the invention is based is therefore to design the device of the type mentioned at the beginning (for example EP-A-003139) in such a way that a considerably smaller force is required for the forming and there is no risk of exceeding the permissible degree of slenderness during upsetting in the first forging phase .

This object is achieved on the basis of the device of the type mentioned at the outset in that only a single pair of such mutually coupled movable tool holders is provided in the device, an additional pair of tool holders immovable during the working stroke being coupled to the base frame to which the parallelogram guide consisting of articulated levers is coupled is rigidly attached, which is equipped with a clamping mechanism that closes this pair of tool holders and in this immovable pair of tool holders, in addition to the other tools used to design the crank cheek, bearing journal or crank pin, also such tools are arranged which serve to determine the mutual angular positions of the adjacent crank cheeks in the crankshaft.

The device according to the invention differs from the known devices for forging monolytic crankshafts in that, according to the invention, only a single pair of such mutually coupled movable tool holders is provided, an additional second tool holder pair which is immobile during the working stroke and being rigidly fastened to one of these tool holder pairs Closing clamping device is equipped and in this immovable pair of tool holders, in addition to the tools used for crank cheek, journal or crank pin design, such tools are also arranged which serve to determine the mutual angular position of adjacent crank cheeks in the crankshaft.

wobei N_P, α und µ die vorstehend genannte Bedeutung haben.
Die Stauchkraft ist also doppelt so groß wie bei den bekannten Konstruktionen. Zum Schmieden können deshalb Pressen mit entsprechend kleinerer Presskraft angewandt werden. Ein zweiter wesentlicher Vorteil der erfindungsgemäßen Vorrichtung beruht darauf, daß sie in Pressen mit verhältnismäßig kleinem Arbeitsraum eingebaut werden kann.In the device according to the invention, the compression force can be approximately calculated on the basis of the following equation:

${\text{P}}_{\text{h2}}{\text{= N}}_{\text{P}}\text{(ctg α-µ)}$

where N _P , α and µ have the meaning given above.
The compressive force is therefore twice as large as in the known designs. Presses with a correspondingly lower pressing force can therefore be used for forging. A second major advantage of the device according to the invention resides in the fact that it can be installed in presses with a relatively small working space.

It is advantageous if in the device according to the invention the additional immovable pair of tool holders outside the space which is located in the plumb line between the head piece and the base.

Furthermore, it is advantageous if in the device the base frame consists of two U-shaped longitudinal beams, the upper arms of each of these longitudinal beams being mutually connected by a tie rod and the two longitudinal beams being connected to one another with crossbeams, one of which is articulated to the articulated lever, which form a parallelogram with the base and the movable tool holders, while the second crossbar forms the lower part of the additional immovable tool holder pair.

It is also advantageous if, in the device according to the invention, the clamping mechanism closing the additional immovable tool holder pair consists of at least one hook which is articulated on the underframe and, when closed, is supported on a half roller which is rotatably mounted in the upper part of the additional immovable tool holder pair.

In an advantageous embodiment of the device, the tool used to determine the angular position of adjacent crank webs is divided and consists of an upper part and a lower part, a recess with peripheral recesses being provided in this tool, which are adjacent to the circumference of the recess according to the required angular positions Crank cheeks of the crankshaft are distributed and a straightening plate with a recess for aligning the bearing or crank pin is arranged in the desired position in this recess.

It is also advantageous if the device has a head piece has vertical guide surfaces which abut vertical guide surfaces which are arranged on the base frame during the working stroke.

The use of the device is more convenient if the upper part of the additional immovable tool holder is equipped with a hook claw which connects it to the head piece during its lifting.

The device according to the invention is intended for forging one-piece crankshafts with several cranks. The device is also suitable for reshaping individual crank offsets for semi-assembled crankshafts. It is also possible to forge individual crank webs which have half pins at both ends. The crankshaft can be built from such crank webs by welding the half journals together.

The device according to the invention can either be installed in a forging press, in which case the head piece is attached to the press ram and the base frame is supported on the press table, or it can be equipped with its own drive.

Fig. 1

die Vorrichtung zur Durchführung des Verfahrens im offenen Zustand, ohne Werkzeugeinlagen, in der Seitenansicht;

Fig. 2

die Vorrichtung gemäß Fig. 1, im vertikalen Längsschnitt;

Fig. 3

die Vorrichtung mit den Werkzeugeinlagen im Moment der Einspannung des zu schmiedenden Materials, welches für die zweite Kurbelwange einer Kurbelkröpfung bestimmt ist, in der Seitenansicht;

Fig. 4

die Vorrichtung gemäß Fig. 3, im vertikalen Längsschnitt,

Fig. 5

die Vorrichtung mit den Werkzeugeinsätzen am Ende der Umformung der erwähnten zweiten Kurbelwange, im vertikalen Längsschnitt;

Fig. 6

die Vorrichtung gemäß Fig. 1, in der Stirnansicht;

Fig. 7

die Vorrichtung mit den Werkzeugeinsätzen am Ende der Umformung der ersten Kurbelwange einer Kurbelkröpfung, im vertikalen Längsschnitt;

Fig. 8

einen Schnitt längs der Linie A - A von Fig. 3;

Fig. 9

den Zuganker eines Längsträgers des Untergestells, in der Seitenansicht;

Fig. 10

den Zuganker in der Draufsicht;

Fig. 11

das Werkzeug zum Festlegen der gegenseitigen Winkellage benachbarter Kurbelwangen, bei Vierzylinderkurbelwellen, ohne Richtplatte, im vertikalen Längsschnitt;

Fig. 12

ein zu Fig. 11 analoges Werkzeug zum Schmieden von Sechszylinderkurbelwellen, in der Stirnansicht;

Fig. 13

ein zu Fig. 11 analoges Werkzeug zum Schmieden von Siebenzylinderkurbelwellen, in der Stirnansicht;

Fig. 14

ein zu Fig. 11 analogen Werkzeug zum Schmieden von Achtzylinderkurbelwellen in der Stirnansicht;

Fig. 15

eine Richtplatte für die Werkzeuge gemäß Fig. 11 bis 14, im vertikalen Längsschnitt;

Fig. 16

diese Richtplatte in der Stirnansicht;

Fig. 17

das Werkzeug zum Festlegen der gegenseitigen Winkellage benachbarter Kurbelwangen, mit eingelegter Richtplatte, welche zum Schmieden der zweiten Wange einer Kurbelkröpfung eingestellt ist, in der Stirnansicht bei fixiertem Lagerzapfen;

Fig. 18

das Werkzeug gemäß Fig. 17, wobei die Richtplatte zum Schmieden der ersten Wange einer Kurbelkröpfung eingestellt ist und der Kurbelzapfen fixiert ist;

Fig. 19

das Werkzeug gemäß Fig. 17 oder 18, wobei die Richtplatte zum Schmieden der ersten Wange einer Kurbelkröpfung an einer Welle eingestellt ist, an der die benachbarte Kröpfung unter einem anderen Winkel ausgerichtet ist als in Fig. 18, wobei der Kurbelzapfen fixiert ist;

Fig. 20

die Anordnung der Werkzeuge beim Klemmen des zu schmiedenden Materials zur Umformung der ersten Kröpfung einer Kurbelwelle, im vertikalen Längsschnitt;

Fig. 21

ein Diagramm der momentanen Stauch- und Biegegeschwindigkeiten am Anfang des Arbeitshubes;

Fig. 22

die Anordnung der Werkzeuge am Ende der Umformung der ersten Kröpfung einer Kurbelwelle, im vertikalen Längsschnitt und

Fig. 23

ein Diagramm der momentanen Stauch- und Versetzungsgeschwindigkeiten am Ende des Arbeitshubes.

The invention is explained in more detail, for example, with reference to the drawings. Show it:

Fig. 1

the device for performing the method in the open state, without tool inserts, in side view;

Fig. 2

the device of Figure 1, in vertical longitudinal section.

Fig. 3

the device with the tool inserts in Moment of clamping of the material to be forged, which is intended for the second crank arm of a crank crank, in the side view;

Fig. 4

3, in vertical longitudinal section,

Fig. 5

the device with the tool inserts at the end of the deformation of the second crank arm mentioned, in vertical longitudinal section;

Fig. 6

the device of Figure 1, in front view.

Fig. 7

the device with the tool inserts at the end of the forming of the first crank arm of a crank crank, in a vertical longitudinal section;

Fig. 8

a section along the line A - A of Fig. 3;

Fig. 9

the tie rod of a longitudinal member of the underframe, in a side view;

Fig. 10

the tie rod in top view;

Fig. 11

the tool for determining the mutual angular position of adjacent crank webs, in the case of four-cylinder crankshafts, without a straightening plate, in a vertical longitudinal section;

Fig. 12

a tool similar to Figure 11 for forging six-cylinder crankshafts, in the front view.

Fig. 13

a tool similar to Figure 11 for forging seven-cylinder crankshafts, in the front view.

Fig. 14

a tool similar to Figure 11 for forging eight-cylinder crankshafts in the front view.

Fig. 15

a straightening plate for the tools according to Figures 11 to 14, in vertical longitudinal section.

Fig. 16

this straightening plate in the front view;

Fig. 17

the tool for determining the mutual angular position of adjacent crank cheeks, with an inserted alignment plate, which is set for forging the second cheek of a crank crank, in the front view with the bearing journal fixed;

Fig. 18

the tool according to FIG 17, wherein the straightening plate is set for forging the first cheek of a crank crank and the crank pin is fixed;

Fig. 19

the tool according to FIG 17 or 18, wherein the straightening plate for forging the first cheek of a crank crank is set on a shaft to which the adjacent crank is aligned at a different angle than in FIG. 18, with the crank pin being fixed;

Fig. 20

the arrangement of the tools when clamping the material to be forged to deform the first crankshaft crank, in vertical longitudinal section;

Fig. 21

a diagram of the current upsetting and bending speeds at the beginning of the working stroke;

Fig. 22

the arrangement of the tools at the end of the deformation of the first crankshaft crank, in vertical longitudinal section and

Fig. 23

a diagram of the current upsetting and displacement speeds at the end of the working stroke.

The device is installed in a press with a press table 1 and a vertically moving plunger 2, the head piece 3 being fastened to the plunger 2 and the longitudinal members 4 of the underframe being supported on the press table 1. The head piece 3 has horizontal guide surfaces 3a on which an upper tool holder 5 is guided. The head piece also has vertical guide surfaces 3b, which bear against vertical guide surfaces 4a on the side members. The lower ends are articulated to the lower frame by four articulated levers, of which the two outer in the drawing with 6 and the other two inner articulated levers, which are arranged closer to the center of the device, are designated by 7. The upper ends of the articulated levers 6 and 7 are articulated on the lower tool holder 8 and form a parallelogram guide with it and the underframe. The lower tool holder 8 has a driver 8a, which couples it to the upper tool holder 5. The tool holders 5 and 8 together form a mutually coupled pair of tool holders. The lower tool holder 8 is additionally connected to the frame by means of tabs 9. The upper half 10 of a divided tool for clamping the material to be forged is fastened in the upper tool holder 5. The lower half 11 of this tool is fastened in the lower tool holder 8.

In addition to the aforementioned movable tool holders 5 and 8 and the tools 10 and 11 fastened in them, the device is equipped with an additional immovable lower tool holder. The lower part 12 of this tool holder is arranged between the longitudinal beams 4 and at the same time forms a cross member connecting the said beams. A recess 12a for inserting tools is formed in part 12. Similarly, 4 recesses 4d are made in the longitudinal beams for inserting tools, which will be explained in more detail. An additional upper tool holder 13 is also provided in the device. This upper tool holder 13 forms together with the lower tool holder, which consists of the part 12 and the recesses 12a and 4d
additional pair of tool holders, which is immobile during the working stroke. The additional upper tool holder 13 is not permanently connected to the head piece, but can be hung on it when the device is opened. This makes it easier the operation of the device when inserting the raw rod and when removing the forging. During the working stroke, the additional tool holder 13 is completely independent of the head piece 3.

Two hooks 14 are articulated on pins 14a in the base frame. The second upper tool holder 13 has on its side surfaces projections 13a, in which two half-rollers 15 are rotatably mounted, on which the hooks 14 press because the device is closed.

The additional upper tool holder 13 is equipped with a drawstring 16, which is used for hanging on the plunger 2. The hook claw 13b and the drawstring 16 facilitate the handling of the second upper tool holder 13 when the device is opened.

Between the additional lower tool holder 12, 12a, 4d and the additional upper tool holder 13, the tool used to fix the mutual angular positions of the adjacent crank webs is arranged. This tool consists of three parts. Its lower part 17 is held in the additional lower tool holder 12, 12a, 4d. Its upper part 18 is fastened in the additional upper tool holder 13. A recess 19 is made in these two assembled parts. In the lower part 17 of the tool, a recess 19a is made on the circumference of the recess 19, the center of which lies in the vertical plane of symmetry of the device. The recess 19a is used for forging the second crank arm of each crank crank. In addition, there are further recesses 19b on the circumference of the recess 19 in both parts 17 and 18, 19c, 19d ... 19i, which are arranged in the required angular positions corresponding to the crankshaft to be forged.

The shape of the recess 19 and the arrangement of the recesses 19a, 19b, 19c ... 19i in a shaft with six crank crankings is shown in FIG. 12. FIG. 13 shows that for a shaft with seven offsets, and in FIG. 14 for a shaft with eight offsets.

The third part of the tool for establishing mutual angular positions of the adjacent crank webs in the forged crankshaft is formed by a straightening plate 20 which has a recess 20a on the circumference. The straightening plate 20 has two surfaces 20b, each of which has the shape of a truncated cone segment. The straightening plate is rotatably mounted in the recess 19.

A split tool is provided for reshaping the crank webs, the upper part 21 of which is arranged on the end wall of the upper movable tool holder 5. The lower part 22 of this tool is fastened in the additional lower tool holder 12, 12a, 4d. The end face 21a of the upper tool part 21 and the end face 22a of the lower tool part 22 have the shape of truncated cone segments. In addition, a second tool 23 is arranged in the second upper tool holder 13, which serves to clamp the material 24 to be forged and as a counter-tool for the upper working surface 22b of the lower tool part 22.

Since the device is intended for forging, in particular, long-stroke crankshafts and the available space is limited in the press, the base of the device consists of two longitudinal beams 4 between which two cross members 25 and 12 are arranged, the second cross member simultaneously forming the lower part of the additional tool holder. Both the cross member 25 and the lower part 12 of the second tool holder have side projections, which are denoted by 25a in Fig. 6 and 12a in Fig. 1. These projections engage in corresponding recesses in the side members 4. The whole is clamped together with transverse screws 26.

Each side member has a U-shaped outline. Its upper arms are connected to one another with a double-T-shaped tie rod 27, the central part 27a of which is parallel to the longitudinal beam 4 and engages in longitudinally extending recesses in the upper arms of the longitudinal beam. The transverse end parts 27b of the tie rod are supported on the end faces 4b and 4c of the side member 4.

The use of U-shaped side members reinforced by tie rods 27, which have recesses 4d for fastening tools, and the arrangement of the lower tool holder part 12 in the space between the side members 4, as well as the articulation of the hooks 14 on pins 14a, the axes of which are vertical run along the side members results in a small width B of the device (Fig. 6), which is of significant importance because of the limited distance between the columns of the press.

The device works as follows: The press ram is raised into its upper position. On the hook claw 3c of the head piece is the hook claw 13b of the additional upper tool holder 13, which holder is also connected to the plunger 2 by the tension band 16. The lower tool holder 8 and the upper tool holder 5 are pushed all the way to the left using hydraulic cylinders, not shown in the drawing. In this position, the articulated levers 6 and 7 are inclined to the right to the vertical, ie in the direction of the additional lower tool holder 12, 12a, 4d. The hooks 14 are pivoted to the right.

Most forging presses have an extendable press table. The lower part of the device can thus be extended outside the working area of the press. This simplifies the insertion of the raw rod into the device and the removal of the finished forgings from the tools after the working stroke.

When the first crank arm is forged on the first crank crank of the crankshaft (FIGS. 20 and 22), the lower part 20 c of a divided straightening plate, which is a clamp for the right end part of the to be forged material. The upper part 20d of this divided straightening plate is placed on the upper part 18 of the tool used to set mutual angular positions of the crank webs.

The preheated raw rod 24 is placed on the lower part 11 of the divided clamping tool for the material, as well as on the lower part 22 of the forging tool and on the lower part 20c of the straightening plate. The press table with the lower parts of the device is pushed into the press.

The press is started. As soon as the tool 23 and the upper part 20d of the straightening plate touch the raw rod, the press is shut down and the hooks 14 are pivoted to the left. They then press on the half-rollers 15, which are rotatably mounted in the projections 13a of the second upper tool holder. As a result, this tool holder 13 is pressed against the lower tool holder 12, 12a, 4d. The press is started again, whereby the raw rod 24 comes into contact with the tools 10 and 21, so that its left part is clamped. The device is now closed and the raw rod is clamped on both the left and the right side. The lower tool holder 8 is coupled to the upper tool holder 5 by its driver 8a.

The second upper tool holder 13 is thus automatically released from the head piece 3 and the drawstring 16 can be removed. When the press ram continues to run downward, the articulated levers pivot to the right, as a result of which the lower tool holder 8 together with the coupled upper tool holder 5 mounted on the horizontal guide surfaces is displaced to the right. In the first phase of this movement, the rod section arranged between the end faces of the tools 11, 21 and 22, 23 is compressed and simultaneously bent, which is shown in FIG. 21. Here, with R the length of the articulated lever 6 and 7, measured between the axes of the upper and lower joints, with r the entire path of bending and pushing through, with S the total compression path, with α₁ the angle of inclination of the articulated lever 6 and 7 at the beginning of Working strokes, with Δ S₁ the instantaneous initial speed of upsetting and with Δ r₁ the instantaneous initial speed of Bending and moving. From Fig. 21 it follows that the instantaneous horizontal upsetting speed Δ S₁ of the movable tool holder with the tools fastened in them is greater than the instantaneous vertical upsetting or displacement speed. The vertical component of motion causes the forged material to bend. In the following phases of the working stroke, the compression speed decreases. At the same time, the bending or displacement speed increases, which is shown in Fig. 23, in which R, r and S have the same meaning, and Δ S₂ mean the instantaneous final speed of upsetting, Δ r₂ the instantaneous final speed of bending or displacing. The end faces 21a and 22a of the tools 21 and 22 approach each other. In the final phase of the working stroke, the crank arm is formed between these work surfaces.

During the entire working stroke of the press, the vertical guide surfaces 3b of the head piece 3 slide on the vertical guide rails 4a of the underframe and take over the frictional forces which arise when the upper tool holder 5 is moved on the horizontal guide surfaces 3a. After completion of the working stroke, the hooks 14 are pivoted to the right with hydraulic cylinders, not shown in the drawing. The press ram 2 is returned until the hook claws 3c and 13b interlock. The press is stopped in this position. The tension band 16 is stretched between the upper tool holder 13 and the plunger 2, after which the plunger is returned to the stop. The forging is removed from the device. The tool holders 5 and 8 are returned to their left position with hydraulic cylinders, not shown in the drawing. When the second crank arm of the first crank crank is forged, the correspondingly heated forging obtained in the first working stroke is inserted into the device in a manner similar to that described above, with the difference that the pin arranged at the beginning of the first crank arm is inserted into the lower recess 19a . In the recess 19, the leveling plate 20 is now inserted so that the crank pin hits the recess 20a. The further forging process is analogous to forging the first crank arm. You get a shaft with a crank crank.

After opening the device, removing the forgings and returning the tools to their original position, you can start forging the first crank arm of the second crank crank. This is analogous to the forging of the second crank arm, with the difference that the crank pin forged in the previous working stroke is inserted into that of the recesses 19b, 19c ... 19i, which corresponds to the required angle between the first and the second crank offset.

After the first crank cheek of the second crank is forged, the second cheek of this crank is forged analogously to the second cheek of the first crank.

During the forging of the following crank webs, it is advantageous to support the already forged parts of the crankshaft accordingly. The inserts 28, 29 and 30 serve to counteract undesirable deformations of the finished crankshaft parts.

With the device, it is favorable to forge crankshafts in which all bearing journals and crank journals have the same dimensions, since they can be successively forged in the same tools. This requirement only concerns the forging itself. The finished crankshaft after machining can have differently dimensioned crank and shaft journals. But you can also forge crankshafts in which the bearing journals and crank journals have different dimensions. However, a larger range of tools is required for this.

A major advantage of the device is that it has two assemblies of different sizes, only the dimensions of the smaller ones being limited by the size of the working space in the press. The first assembly is arranged in the drawing on the left side of the device and is located between the press ram 2 and the parts 4 and 25 of the underframe. This assembly is smaller (height h in Fig. 7) and contains the device parts that are movable during the working stroke, i.e. the head piece and only a pair of the coupled tool holders 5 and 8, one of which is guided on the guide surfaces 3a in the head piece 3 is, while the second is articulated with articulated levers 6 and 7 on the underframe.

The left part of the raw rod 24 is clamped in the tools 10 and 11 fastened in these tool holders 5 and 8. The second assembly of the device is higher (height H in Fig. 7). This assembly lies outside of the perpendicular between the head piece 3 and the other right parts of the base existing space. It contains the parts of the device which are immobile during the working stroke, namely the additional tool holders 12, 12a, 4d, 13 with the tools 22, 23, 17, 18 and 20 fastened in them, which are used for shaping the crank web and for defining the angular position of adjacent crank webs serve. The forged parts of the crankshaft are also included in the second assembly. This second assembly is not in the work area of the press, so its height H is not limited by the height of the work area. The crank arm can therefore be reshaped outside the space between the head piece and the base. This makes it possible to forge long-stroke crankshafts on presses with a relatively small working space.

Another advantage of the device is that, unlike the known devices, all crankings can be produced with the same tool 17, 18 and 20 for determining the angular position of adjacent crank webs. The straightening plate 20 of this tool can be used to forge all crankshafts of the same type, apart from the number of crankings in the crankshaft. This limits the number of tools used, which reduces production costs.

Claims (7)

1. Apparatus for forging crankshafts, consisting of a base frame (4, 25) and a head piece arranged above this base frame (4, 25) and movable in a reciprocating manner in the direction of this frame, two mutually coupled, movable tool holders (5, 8) being arranged in the space between the head piece and the base frame (4, 25), which tool holders (5, 8) are guided perpendicularly on the head piece or at an angle to its direction of movement and which are coupled to the base frame (4, 25) by a parallelogram guide consisting of articulated levers (6, 7), tools (10, 11, 21) being fastened in the tool holders (5, 8) for the shaping of the crankwebs, bearing journals and crankpins, characterised in that only a single pair of such mutually coupled, movable tool holders (5, 8) is provided in the apparatus, an additional tool-holder pair (12, 4d, 13), fixed during the working stroke, being rigidly fastened to the base frame (4, 25) to which the parallelogram guide consisting of articulated levers (6, 7) is coupled, which additional tool-holder pair (12, 4d, 13) is equipped with a clamping mechanism (14, 15) closing this tool-holder pair, and, apart from the further tools (22, 23) serving to shape the crankwebs, bearing journals and crankpins, such tools (17, 18, 20) which serve to fix mutual angular positions of the adjacent crankwebs in the crankshaft are also arranged in this fixed tool-holder pair (12, 4d, 13).
2. Apparatus according to Claim 1, characterised in that the additional fixed tool-holder pair (12, 4d, 13) is arranged outside the space which is located perpendicularly between the head piece (3) and the base frame (4, 12, 25).
3. Apparatus according to Claim 1, characterised in that its base frame consists of two U-shaped longitudinal members (4), the top arms of each of these longitudinal members being mutually connected by a tie rod (27) and the two longitudinal members being connected to one another by cross pieces, of which one (25) is linked to the articulated levers (6, 7) which form a parallelogram with the base frame and the movable tool holders (5, 8), while the second cross piece (12) forms the bottom part of the additional fixed tool-holder pair (12, 4d, 13).
4. Apparatus according to Claim 1, characterised in that the clamping mechanism closing the additional fixed tool-holder pair (12, 4d, 13) consists of at least one hook (14) which is linked to the base frame (4, 12, 25) and, in the closed position, is supported on a semiroller which is rotatably mounted in the top part (13) of the additional fixed tool-holder pair.
5. Apparatus according to Claim 1, characterised in that the tool serving to fix mutual angular positions of the adjacent crankwebs is split and consists of a top part (18) and a bottom part (17), an aperture (19) having peripheral recesses (19a, 19b...19i) being provided in this tool, which recesses (19a, 19b...19i) are distributed on the periphery of the aperture in accordance with the required angular positions of the adjacent crankwebs, and in that an orientation plate (20) having a recess (20a) for orientating the bearing journal or crankpin into the desired position is arranged in this aperture.
6. Apparatus according to Claim 1, characterised by a head piece (3) having vertical guide surfaces (3b) which bear during the working stroke against vertical guide surfaces (4a) which are arranged on the base frame (4, 12, 25).
7. Apparatus according to Claim 1, characterised in that the top part (13) of the additional fixed tool holder is equipped with a hook claw (13b) which connects it to the head piece (3) during lifting of the latter.

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