EP1568423B1 - Method of preforming a blank by rolling - Google Patents

Description

The invention relates to a method and a device for preforming a blank in a massive forming process, according to the preamble of claims 1 and 6, respectively.

State of the art

In the process chain of drop forging, an intermediate mold is required depending on the final shape of the forging. By a mass accumulation or mass reduction at certain points of the workpiece so the result of the subsequent drop forging should be improved. To obtain this intermediate form are methods such. B. the cross rolling or stretching rolls known.

Further methods are in the textbook of Umformtechnik ", Kurt Lange, Springer-Verlag 1974, page 46, shown.

Both the cross rolling and the stretch rolling allow an optimal geometrical adaptation of the mass distribution on the intermediate molding to the requirements of the drop forging of elongated parts. The material surplus in the final shape is thereby minimized and evenly distributed and allows a low-burr drop forging. By adapting the rolled intermediate form to the final shape of the finished forged part Constant forming forces and thus minimum tolerances of the finished parts in the pressing direction are ensured. Furthermore

Relative movements are reduced in the pressure contact zone between the workpiece and engraving and thus reduces the wear of the dies. By using pre-forming processes upstream of die-forging, material consumption can be reduced by up to one-third.

In massive forming, there has recently been a trend towards ever higher stroke rates. This is achieved in particular by the use of modern crank presses with fully automatic workpiece transfer for drop forging. The known preforming methods, in particular the transverse rolling and the stretching rolls have the disadvantage that they are difficult to integrate into a fully automatic forging process with automatic workpiece transport. The reasons for this are the relatively high cycle times when transverse or stretching rolls, as well as the partially unsuitable for an automated manufacturing process position of the workpiece at the end of the rolling process.

Another disadvantage is the complex, constructive design of the preforming device and the associated high costs.

From the document DE-A-100 48 312 a method and an apparatus for carrying out the method according to the preamble of claims 1 and 6 has become known. In this ironing apparatus, the workpiece is deformed by means of a movable contour roller, which in turn is supported on a sliding housing with a conical shaped piece. A variable contour can not be produced by means of such a device.

Task and advantage of the invention

The invention has for its object to develop a method and apparatus for preforming a forging, which is inexpensive at a high productivity and can be integrated in the transfer of a forging press.

This object is achieved by a method and a device by the characterizing part of claims 1 and 7 solved. In the dependent claims advantageous and expedient refinements are proposed.

The core idea of the invention is a method in which a stationary blank is deformed by at least one, preferably two, roller continuously moving along a predetermined contour. The feed movement of the contour roller is effected by a linear drive.

The path of the contour rollers during the feed is preferably determined by two profile inserts whose profile corresponds to the negative shape of the preform. Due to the feed movement and the shape of the contour rollers, the blank is plastically deformed by the contour of the profile inserts. As a final result of so-called roll preforming, e.g. To obtain a rotationally symmetrical preformed blank, the contour rollers must be performed with the appropriate radius. Alternatively, it is also possible to use a contour roller only on one side. In this case, the blank is supported during preforming on the opposite side by a fixed stop.

Also conceivable is a solution in which the contour rollers are supported on the blank side facing away from straight plates, which change the distance between the plates to the blank axis by servomotors so that the blank is preformed accordingly. As actuators, for example servomotors or hydraulic motors can be used.

The blank is fixed with a turning pliers. After a forming pass, the turning pliers and thus the partially formed blank are rotated by 90 °. In this position, the rolling process is repeated. As a result, the blank has an approximate rotationally symmetrical intermediate form achieved. It is also conceivable to drive more than two rolling cycles with a correspondingly smaller angle of rotation in order to improve the preforming result. If, for example, the blank consists of a flat bar, a forming pass can of course also result in the required intermediate shape.

During the rolling process, the blank is held by the turning pliers and supported by, for example, two ejector bolts radially from below. Another function of the turning pliers is to compensate for a lengthening or stretching caused by the preforming. At the end of the preforming process, the profile inserts are designed such that the contour rollers move out of the forming area. The ejector bolts now lift the preformed blank onto the workpiece transport plane. This is then gripped by the transfer system of the forging press and is transported through the corresponding forming station.

The device according to the invention for this method can be positioned as an independent forming unit or also in the stand area of the forging press. As a result, the device for roll preforming can be inexpensively integrated into the existing press transfer device.

An independent solution in which the proposed device is placed in front of the forging press with separate feeding device is also possible. The proposed preforming method can be used both with and without additional heat treatment. In addition, the process is suitable for different materials such as steel or aluminum.

At high degrees of deformation during preforming, the device according to the invention can also be operated several times one above the other. According to the number of devices used, the degree of deformation increases. The application is the same when multiple devices arranged one above the other as when using only one device. To push through the contour rollers between the blank and the profile inserts, as already mentioned, a linear force in the direction of the blank axis is necessary. Preferably, this linear force is generated by a hydraulic drive, but also a power transmission by a mechanical drive is possible.

The power transmission from the drive to the contour rollers must be such that they are freely movable in a plane perpendicular to the direction of movement in order to follow the contour of the profile inserts can. This is achieved by a clevis on the two arms are hinged and scissor-shaped. At these two arms, the two contour rollers are rotatably mounted. The arms on which the contour rollers are mounted can additionally be acted upon by a spring force such that the contour rollers rest securely on the contour during retraction and extension. During preforming, the blank is supported by a stop plate against the feed direction or force.

In order to improve the forming result, the device according to the invention can be equipped with a guide sleeve, which stabilizes the blank during the forming process. This is achieved by a sleeve which encloses the blank until just before the region of the deformation and taken by the articulated arms in the direction of the blank axis against a spring force becomes. As a result, a bulging or an inclined position of the blank is prevented by the forming.

In order to be able to absorb the reaction force of the forming force, the profile inserts must be fixed in a plane perpendicular to the blank axis. This can be done by a mechanical stop, but also other constructive solutions, such as a dimensionally stable frame that surrounds both profile inserts, are possible.

The profile inserts, the stop plate and the frame thus form a device, or a tool for roll preforming. This is done by known methods, e.g. clamped with wedges or clamps on a fixed table so that the tool can be changed without great effort. Of course, only an exchange of profile inserts can take place. A mechanical stop in and against the feed direction of the hydraulic cylinder on the fixed table is useful.

Further advantages and details of the invention will become apparent from the description and the figures of an embodiment.

Figur 1

Vorrichtung zum Rollvorformen als Isometrieansicht

Figur 2

Draufsicht zu Beginn des Rollvorformens

Figur 3

Draufsicht während des Rollvorformens

Figur 4

Draufsicht am Ende des Rollvorformens

Figur 5

Vorrichtung zum Rollvorformen als Schnittdarstellung

The figures show:

FIG. 1

Device for roll preforming as an isometric view

FIG. 2

Top view at the beginning of roll preforming

FIG. 3

Top view during roll preforming

FIG. 4

Top view at the end of roll preforming

FIG. 5

Device for roll preforming as a sectional view

Description of the embodiment:

FIG. 1 shows a device 1 for roll preforming. You can see a table 2 on which a solid, rigid frame 4 is fixed with clamps 3. On the side walls of this frame 4 two profile inserts 6 are attached. These profile inserts have on the side directed towards the middle on a contour that is matched to the final contour of the preformed blank 7. The blank 7 is supported on one side on a stop plate 5, which is also attached to the frame 4. At the other end of the blank of a turning pliers 13 is held.

In Figure 5, the device 1 for roll preforming is shown in section. To see are ejector pin 12, which supported the blank 7 from below during the preforming process. Between the profile projections 6 and the blank 7 are two contour rollers 8, which are moved by a drive, not shown, for example, a hydraulic cylinder in the direction 9 via a drive linkage 11 on the outer contour of the profile inserts 6 along. The outer contour is thereby pressed into the blank 7 via the contour rollers 8. The profile inserts 6 are performed at the beginning and at the end with a contour 7 removed from the blank, so that the contour rollers 8 move away from the blank 7 at the beginning and at the end of the preforming process. The contour rollers 8 are pressed, for example by a spring force acting on the arms of the drive linkage 11 to the contour of the profile inserts 6. The drive linkage 11 consists essentially of 2 arms, which are mounted in a common pivot point 10.

As soon as the contour rollers 8 have moved away from the preformed blank 7 at the end of the preforming process, this can be done by the Auswerferbolzen 12 are raised and transported by an automatic transfer system, for example, in a drop forging press.

Optionally, after turning the turning pliers 13 and the blank 7 about its longitudinal axis, the preforming operation against the direction 9 can be repeated. By repeatedly repeating the roll preforming, an approximately rotationally symmetrical preformed blank 7 can be produced.

FIGS. 2, 3 and 4 show different preform stages. FIG. 2 shows the beginning of the preforming process. The blank 7 is not yet transformed. The contour rollers 8 are still in the inlet region of the outer contour of the profile inserts. 6

In FIG. 3, the contour rollers 8 have passed approximately half of the forming section, and the resulting proportional deformation of the blank 7 is clearly visible.

In FIG. 4, the contour rollers 8 have already moved out of the region in which a deformation takes place and allow the preformed blank 7 to be lifted by the ejector bolts 12.

The invention is not limited to the illustrated and described embodiment. It also includes all professional training that fall under the wording of the claims.

LIST OF REFERENCE NUMBERS

1

Roll preforming device

2

table

3

clamps

4

frame

5

stop plate

6

profile inserts

7

blank

8th

contour rollers

9

driving direction

10

pivot point

11

drive linkage

12

ejector

13

turning clamp

Claims (17)

1. Method for producing a reforming part from a blank (7) for subsequent solid reforming, wherein the blank (7) is plastically deformable and the plastic deformation is carried out in a continuously progressive manner on the stationary blank, characterised in that shaping rollers (8) located on a drive rod system (11) are supported on profile inserts (6) of any shape for the corresponding shaping of the blank (7), and in that after rotation about the longitudinal axis of the blank (7) the preshaping method can be repeated as often as desired increasing the amount of shaping.
2. Method according to claim 1, characterised in that the blank can be heated prior to the preshaping procedure.
3. Method according to claim 1 or 2, characterised in that after the completion of the reforming procedure the preshaped part is sent automatically to the forging process without further heat treatment.
4. Method according to claim 1, 2 or 3, characterised in that the blank can have any cross sectional shape.
5. Method according to one of the preceding claims 1 to 4, characterised in that without changing the position of the blank the amount of shaping is increased by several shaping procedures.
6. Device for performing the method according to claim 1 for preshaping a blank (7), wherein the fixed blank (7) is shaped by at least one movable contour roller (8) in longitudinal and transverse direction, wherein the path of the contour roller (8) can be defined by the outer contour of a fixed profile insert (6) and the outer contour of the profile insert (6) corresponds to the projected geometry of the preshaped part, characterised in that at least two contour rollers (8) are provided, wherein the contour rollers (8) are mounted rotatably on fork or scissor-shaped arms (11) which in turn are connected at a common centre of rotation (10) to the linear drive.
7. Device according to claim 6, characterised in that the contour roller (8) can be displaced by means of a linear drive in the direction of the blank longitudinal axis.
8. Device according to claim 6 or 7, characterised in that the distance of the contour roller (8) from the blank axis can be influenced by positioning motors during the shaping.
9. Device according to claim 8, characterised in that the positioning motors act on straight plates on which the contour rollers are supported during the shaping.
10. Device according to claim 6, characterised in that the two arms (11) are actively connected to a spring, the spring force of which pushes the arms (11) against the profile inserts (6).
11. Device according to one of claims 6 to 10, characterised in that the linear drive is obtained via a hydraulic cylinder or a lever mechanism.
12. Device according to one of claims 6 to 11, characterised in that the blank (7) is supported by a stop plate (5) during the shaping process by the advance of the contour rollers (8).
13. Device according to claims 6 to 12, characterised in that the blank (7) is guided during the reshaping by a sleeve which can be moved together with the contour rollers (8) in the direction of the blank axis.
14. Device according to claims 6 to 13, characterised in that the profile inserts (6) and the stop plate (5) are surrounded by a closed frame (4).
15. Device according to one of claims 6 to 14, characterised in that the blank (7) can be supported and lifted before and after preshaping by bearings (12) which are in the form of ejectors.
16. Device according to one of claims 6 to 15, characterised in that the blank (7) is held by a reversing grip (13) which is rotatable in the longitudinal axis of the blank.
17. Device according to one of claims 6 to 16, characterised in that several preshaping devices (1) can be driven by a common linear drive.

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