DE8801504U1 - Multi-ram forging machine - Google Patents

Description

^mwälte j'' [ I Pdtent&ttorneys VON KREISLER '"' 3ELTING'' WERNER

Delchmannhaue at the main station D-50O0 COLOGNE 1

Df.-lng. by Kreisler 11973 Dipl.-Chem. Alek von Krelsler Dipl.-Ing. G. Selting Dr H-K Werner Dr. Ing. K. Schönwald

Dr. J. F Fues

Dipl-Chem Carola Keller

05.02.1988 Sch/str

Company Eumuco Aktiengesellschaft for Mechanical Engineering Josefstraße 10, 5090 Leverkusen 1

'Multi-ram forging machine'

The invention relates to a multi-ram forging machine in which the rams carry interchangeable forging tools, of which at least two diametrically opposed forging tools act simultaneously on the forged workpiece and the rams are provided with a piston-cylinder unit in which a chamber for the hydraulic pressure medium is located in the cylinder in front of and behind the piston.

Telephone: (0221)131041 Accounts: Telex: 888 2307dopad .".."..". .'· '.'"..".'. SaI. Oppenheim Jr. & Oe.. Cologne (bank code 37&Oacgr;3&Ogr;2&Ogr;&Ogr;) Account no. IO

Fax: (0221)134297 .".,".'. ', '. '".II '.. "fleutscheBankAG.Köln(BLZ37070060)Kto.Nr.i165018

Telegram: Dompatent Köm · _&idiagr;# · · _>( · · _#§ · _i j _{§ t#i} » · _>> · JPostgiro Köln (BLZ 37&Ogr;1&Ogr;&Ogr;5&Ogr;) Kto. Nr 654-5O0

Forging machines are known in various designs. They are used for forging (stretching » round swaging) of long, axially symmetrical workpiece shapes.

The use of a hydraulic drive system is known in general forging machines.

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OCX UJ.C9CII UCJVOJlllLCll &Pgr;&Igr; I U1. X CUO 0JO UCIIlCI 1 JmZI=J. JL m IVA CIS OA^lI the switching elements for the hydraulic control system are removed from the piston-cylinder units in the usual arrangement, and the hydraulic switching elements are switched electromagnetically as usual. The electromagnetic excitation during each switching process and the arrangement of the switching elements away from the piston-cylinder unit result in switching times and pressure build-up times for each movement process which disadvantageously limit the achievable stroke frequencies of the known forging machines to a low level. In addition, with such a design the switching system and thus the entire machine becomes relatively complex.

In the known hydraulic drive systems, the working stroke or the respective end positions of the piston are usually determined using fixed mechanical end stops or, if necessary, using path-dependent controls. This type of design generally has the disadvantage that it is not possible to set or control the working stroke of the working piston with the required accuracy, both in terms of its end positions and its speed, using hydraulic means.

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With multi-ram forging machines, the problem arises of connecting several working cylinders together, which are to work in absolute synchronism and with the same stroke on the output side. With regard to such a problem, the known design of working cylinders has the disadvantage that the working stroke in the individual working cylinders in the case of combined working cylinders cannot be adjusted, in particular it cannot be regulated to an identical value for several working cylinders, and when executing the stroke, the movement and synchronism cannot be influenced with the required control accuracy.

Especially in the case of large-volume working cylinders, there is currently no known way of interconnecting several large-caliber working cylinders with closed position and/or speed control loops in such a way that the multiple control loops required are synchronized.

The object of the invention is to create a multi-ram forging machine which is simple in construction with regard to the hydraulic drive device, requires little effort, has a simple function and works reliably and allows a significant increase in the stroke frequency for the large piston-cylinder units required, whereby in particular the control and influencing of the working stroke of the cylinder pistons is adjustable and controllable. A further object of the invention is to carry out the control of the working cylinder in such a way that several working cylinders

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can be operated together in a simple manner with speed and stroke synchronization, without the necessary control system becoming complicated.

The invention is characterized in that the control of the pressure medium required for the ram movement is arranged directly in the piston-cylinder unit and that the pressure medium required for initiating movement of the working piston is not controlled via electromagnetically excited valves.

For this purpose, the piston has a valve on the side opposite the forging tool, the valve rod of which, carrying the valve cone, is provided with an actuator, e.g. a servo unit. Behind the valve seat, a flow hole in the piston leads to a third chamber in the cylinder. The first chamber in front of the valve seat is pressurized by the pressure medium and the third chamber is connected to the medium container for the pressure medium via a line without pressure. The second middle chamber with a smaller pressure area intended for the retraction of the piston is pressurized with a pressure medium at a predetermined pressure.

Such a hydraulic drive system is extremely simple. The stroke movement and the stroke position of the working piston are achieved directly with just one valve cone movement. This achieves a movement characteristic that is directly dependent on the actuator, i.e. the path and speed of the working piston movement. No additional valves need to be switched on for the working cylinder.

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This results in a very high stroke frequency, as there are practically no switching times and the pressure build-up times are only dependent on the output of the pressure generation pump located at a central location. This simple control device also increases the operational efficiency of the system.

Each tappet can have its own piston-cylinder arrangement with an electronically controlled actuator as

Servo unit. The movement characteristic diame- f

trally opposite working piston is with the help of j

known position measuring devices of the working movement syn-!

chronized. Likewise, the movements of all four ar- j

rams can be synchronized in such a way that simultaneous ' working movements and also alternating, as pairwise

successive synchronized work movements j

genes arise. .

The electronic control system controls the actuators in such a way that constant stroke lengths are achieved regardless of the penetration depth of the forging tool. The stroke lengths can be preselected according to the forging requirements, especially when preforming work or finishing work is to be carried out. In addition, the stroke position can be changed. This allows the work ram to be turned to the front working position and at the same time the thickness of the workpiece to be controlled, i.e. the intended forging dimension is controlled.

The valve seat of the only valves of the piston-cylinder arrangement in a forged unit is advantageously

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Working piston attached. The valve cone works directly with the valve seat. The second chamber, designed as an annular space with a smaller pressure area, automatically causes the retention and retraction movement of the working piston without any control.

Advantageously, the middle chamber is under a constant pressure.

According to a further feature, the servo units are designed as actuators for simultaneous lifting movement, uniform stroke length and uniform and/or pairwise stroke position adjustment of all cylinder units. Preferably, they are electronically controllable and programmable.

The invention is explained below with reference to the embodiments shown in the drawing.

Fig. 1 shows an embodiment of the forging machine according to the invention, partly in 2Q section and partly in elevation and in

Scheme.

Fig. 2 is a side view of the forging machine of Fig. 1.

The forging machine 1 shown has four forging units 2, 3, 4 and 5, which are mounted in a frame 6. The forging units are arranged in the same way

The further explanation therefore only refers to the forging unit 2 shown in the sectional view.

The forging units 2 to 5 are arranged evenly distributed radially around the forging axis, in which the workpiece 8 is located, so that two forging units are diametrically opposite each other. Each forging unit has a ram 9, to the front end of which an exchangeable forging tool 10 is attached. The forging tools 10 can act on the workpiece 8 at the same time, or two opposing rams can act on the workpiece one after the other.

The forging unit is designed as a hydraulic cylinder 11 in which a piston 12 slides, to which the ram 9 can be attached. Piston 12 and ram 9 are advantageously formed as one piece. On the side of the hydraulic cylinder 11 facing away from the tool there is a chamber 14 for the pressure medium. Below the piston 12 there is a further chamber 15 which serves for the retraction of the piston 12. The piston 12 is provided on the side facing the chamber 14 with a valve seat 17 which is fastened in a holding plate 18. The cylinder 11 is closed off by a cover 19 which forms a guide for a valve cone rod 20 which is formed at the front end as a counterpart to the valve seat 17. The valve cone rod 20 is connected to an actuator 23, which can be a linear actuator and which moves to the pre-programmed stroke position and executes the pre-programmed stroke movement in the piston chamber.

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The actuator 23 is arranged on a bracket 24 of the machine housing 6.

; From the valve seat 17 leads inside the piston 12

a bore 25, which opens into two or more openings 28 from the piston 12 into a chamber. The guide bush 18 is provided with an undercut on the outer diameter.

: From a hydraulic drive (not shown)

} unit leads a supply line 30 to the cylinder chamber 14

^J 10 as the inlet side for the pressure medium. The chamber 26 is

connected to one or more pipes 32, which , with a tank (not shown) as outlet of the

pressure medium. The medium flows

Ü. in the circuit through the forging unit. To the ring

A line 31 is provided in the chamber 15 below the piston 12, through which the pressure medium is also supplied, which is under a constant pressure.

In order to give the piston 12 or the tappet 9 a forward movement S, the valve cone rod 20 moves in the direction

20 valve seat, whereby the free flow of the pressure medium through the valve seat is restricted, which results in a pressure build-up in the cylinder chamber 14 and moves the piston 12 forwards. The valve cone only reaches the valve seat 17 when increasing resistance (penetration of the forging tool into the forging material) occurs.

The tappet 9 with the piston 12 moves forward until the valve cone rod 20, after reaching a preselected forward position, moves to a preselected reverse position

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is withdrawn. The pressure medium has free flow through the bore 25, 27 from the chamber 14 to the chamber 26 and back into the medium container through the line 32. The counter pressure which is always present in the middle chamber 15 automatically pushes the piston 12 with the tappet 9 back. The valve cone rod, which is led out of the cylinder through the cylinder cover 19, receives its movement by means of an electrohydraulic actuator 23. The function of the actuator is to move the valve cone forwards and backwards at a preselected speed to a preselected forward and backward position. Due to the movement of the valve cone 2 0, the piston 12, 9 moves in the same movement sequence and thus to the same stroke length and stroke position.

The functional sequence is as follows. The valve cone rod 20 moves to a predetermined position. The valve cone is adjusted using the actuator 23. By preventing the flow of pressure medium through the valve seat 17, a pressure builds up that presses against the piston 12 and thus the tappet 9 and moves it forwards. The forging tool 10 attached to the front end of the tappet 9 penetrates the workpiece. Once the penetration depth has been reached, the valve cone 20 moves back the preselected stroke length. The pressure medium flows from the chamber 14 through the open valve seat and through the bore 25, 27 to the chamber 26 and back through the drain line 32 into the medium container.

The constant pressure in the middle chamber 15 (annular space) causes the return movement of the piston 12 together with

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the plunger 9. This process is repeated with each stroke.

A servo unit 23, which has a measuring and control function, can compare the actual with the target with each movement and regulate it by controlling the servo unit 23. The same actual-target comparisons are carried out and regulated on all four forging units simultaneously for synchronous operation of all forging tools or two pairs of forging tools.

The design of the control devices can also be carried out in a different way than described above. The return pressure device 15, 31 can also be designed as a spring, as a pressure accumulator or as a hydraulic pressure control unit. The actuator 23 can also consist of an electric or pneumatic feed control for the valve cone rod 20 with corresponding initial and end position control. Of importance for all designs of the control device is the fact that even with a large-caliber working cylinder only the smallest control forces are required, since the control rod 20 is located in the flow path of the hydraulic pressure medium and the front surface of the control rod 20 is only acted upon by the relaxed pressure medium flowing to the tank. Even at high pressures in the chamber 14, the control rod 20 can therefore be moved almost effortlessly, which means that it can follow the control signals even faster and more precisely.

The described method of operation is particularly suitable for the realization of large-caliber working cylinders in the order of more than four hundred

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Millimeter nominal width. Since the determination of the end position of the piston during the working stroke*, which results in a defined stopping of the sluggish piston movement in large-caliber working cylinders, is dependent neither on a control of the drive-side pump output nor on a control of the counterpressure force emitted by the return pressure device, these two influencing variables can now be kept constant by controlling the working stroke solely by the almost powerless movement of the actuator 23 interacting with the discharge opening 25 in the piston 12.

When connecting the working cylinders in the multi-ram forging machine, only the synchronization of speed and stroke is required to ensure synchronous movement of the actuators, which run almost without pressure, between the specified start and end positions, since the path and speed of the piston stroke in the working cylinder are only determined by the movement characteristics of the actuators and not by the flow rate of the drive pumps.

- Expectations -

Claims (8)

Expectations 1. Multi-ram forging machine, in which the rams carry forging tools, of which at least two diametrically opposed forging tools act simultaneously on the forged workpiece and the rams are provided with a piston-cylinder unit, in which a chamber for a hydraulic pressure medium is located in the cylinder in front of and behind the piston, characterized in that the piston (12) has a valve (16) on the side opposite the forging tool (9, 10), which consists of a valve seat (17) and a valve cone rod (20), that the valve cone rod (20) is provided with an actuator (23), e.g. a servo unit, that behind the valve seat (17) in the piston (12) a flow bore (25) leads to a third chamber (26) in the cylinder (11), and that the first chamber (14) in front of the Valve seat (17) is pressurized by the pressure medium and the third chamber (26) is connected to the medium container for the pressure medium without pressure by a line (32) and the second middle chamber (15) with a smaller pressure area intended for the retraction of the piston is pressurized with a pressure medium under a predetermined pressure. 2. Multi-ram forging machine according to claim 1, characterized in that the middle chamber (15) is always under a constant pressure. &bull; * · · I Il »1 ·· 3. Multi-ram forging machine according to claim 1 or 2, characterized in that the valve seat (17) is arranged in a separate holding plate (18). 4. Multi-ram forging machine according to claim 1, characterized in that the valve seat (17) forms part of the piston (12). 5. Multi-ram forging machine according to one of claims 1 to 4, characterized in that the piston (12) and the ram (9) form one piece. 6" Multi-ram forging machine according to one of claims 1 to 5, characterized in that a guide bushing (27) is arranged in the cylinder (11), which has the outlet openings (28) for the bore (25) and peripheral surfaces with an undercut. 7. Multi-ram forging machine according to one of claims 1 to 6, characterized in that two pairs of forging tools are fed to the workpiece simultaneously or alternately. 8. Multi-ram forging machine according to one of the claims 1 to 7, characterized in that the servo units (23) are designed as servomotors for simultaneous stroke movement, uniform stroke length and uniform and/or pairwise stroke position adjustment of all cylinder units and that the servomotors are electronically controllable and programmable.