EP3417178B1 - Double acting double rod cylinder for an extrusion press - Google Patents

Description

Technical area

The invention relates to a synchronous cylinder, preferably for use in a forming device, in particular a pressing plant, extrusion plant or ring rolling plant.

Background of the invention

Extrusion and ring rolling systems are devices for the plastic deformation of materials, such as preheated heavy or light metal blocks, by means of a targeted application of force. In the case of an extrusion plant, for example, such a heavy or light metal block, also referred to as a bolt, is driven through a so-called die by means of a hydraulically operated press ram, whereby a semi-finished product with a certain, defined profile is produced. Such extrusion plants go, for example, from the DE 38 36 702 C1 and the DE 10 2012 009 182 A1 emerged.

In addition to the actual application of force for reshaping the workpiece, systems of this type typically have drives for moving or positioning the transducer with the die or other system components. Conventionally, the block pick-up is configured and brought into position over long strokes by means of hydraulic cylinders. For example, the pick-up is moved in this way between a position for changing blocks and a front end position, the working position at which sealing or pressing, venting and stripping takes place. Alternatively, electric motors are used, which move the pick-up between the block change position and the working position.

If electric motors are used, internal forces in the hydraulic cylinders must be overcome. This is particularly true when using synchronous cylinders, in which due to their design - two guided piston rods plus pistons, possibly hollow cylinder pistons - in addition to flow losses, relatively mechanical frictional forces must be overcome. On the other hand, synchronous cylinders are useful in the shaping devices discussed, since they can be switched from towing to working mode over their entire stroke.

The U.S. 6,058,826 A describes a hydraulic cylinder with pistons for power steering.

Presentation of the invention

One object of the invention is to provide a synchronous cylinder which, with a compact, long-lasting design, can be moved efficiently and quickly by an external drive, preferably in an electric or pneumatic motor or a hydraulic cylinder or the like. A further object is to specify a forming device, preferably a pressing system, extrusion system or a ring rolling system, which, with a compact, long-lasting design, realizes an efficient and fast movement of the system between a working configuration and one or more other configurations.

The objects are achieved with a synchronous cylinder with the features of claim 1 and a forming device with the features of claim 10. Advantageous developments follow from the subclaims, the following presentation of the invention and the description of preferred exemplary embodiments.

The synchronous cylinder according to the invention is a hydraulic cylinder, it has an outer cylinder and an inner cylinder introduced therein and arranged concentrically therewith. A displaceable, double-acting working piston is inserted into the inner cylinder. In the case of double-acting hydraulic cylinders or working pistons, there are two opposite piston surfaces to which hydraulic fluid is applied. As a result, the hydraulic cylinder has two active directions of movement. For this purpose, the working piston divides the inner cylinder into two pressure chambers and a hydraulic fluid can be applied from both pressure chambers. If there is a pressure difference between the two pressure chambers, a work force acts on the working piston. The working piston is also connected to a piston rod or formed integrally or in one piece with such, the piston rod preferably protruding from both ends of the outer cylinder and guided there, for example by means of cylinder locks attached to the ends. There is an annular gap between the inner cylinder and the outer cylinder and / or another direct connection, for example in the form of one or more bypass lines.

Furthermore, the synchronous cylinder has a bypass device with two bypass valves which are provided on the opposite sides of the working piston. The above-mentioned annular gap and / or the at least one bypass line are part of the bypass device. The bypass device is set up so that in a certain position or position of the bypass valves, which is referred to here as bypass position, a fluid connection is established between the two pressure chambers via the annular gap and / or the at least one bypass line and in another position or position the bypass valve, which is referred to here as the working position, no such fluid connection (within the synchronous cylinder) is established. In other words: the bypass position allows a fluid exchange between the pressure chambers in that hydraulic fluid flows from one pressure chamber via the annular gap and / or the at least one bypass line into the other pressure chamber, while such a fluid exchange is prevented in the working position.

The synchronous cylinder described has a compact design in which a bypass function, also referred to as a bypass function, is implemented in a technically simple manner. The ring line, which is created by the concentric cylinders - inner cylinder and outer cylinder - allows a low-loss bypass flow. Same goes, in addition to the ring line or, alternatively, also for the at least one bypass line outside the cylinder housing. The working piston can thus be moved quickly and energy-efficiently by an external drive. Thanks to the synchronous construction, the hydraulic cylinder can develop its full design force in every stroke position.

Due to the technical effects and advantages described above, the synchronous cylinder can be used particularly advantageously in the area of forming devices, in particular pressing systems, extrusion systems or ring rolling systems. The extrusion plants occupy a prominent position here, since there a rapid movement of the transducer or possibly other plant parts over a large stroke is desirable. The synchronous cylinder according to the invention here combines in a synergetic manner a working mode and a towing mode over the entire stroke. In particular, the synchronous cylinder can be switched over the entire stroke between working mode and towing mode, i.e. that operation in which the bypass valves are brought into the bypass position and the synchronous cylinder is moved by an external drive, such as one or more electric motors. The flow losses and the internal friction of the synchronous cylinder are reduced, so that the towing operation can be carried out in a power-saving, energy-efficient and fast manner.

The piston rod is preferably designed such that it extends from the working piston on both sides and has the same diameter on both sides. In this way, the synchronous cylinder can be implemented in a technically particularly simple manner, since in the case of a cylindrical working piston the contact surfaces for exposure to the hydraulic fluid are the same size on both sides. A hollow cylindrical piston, which is disadvantageous in terms of flow, can be dispensed with. In this case, at least one of the bypass valves is preferably guided on the piston rod, this preferably surrounds the piston rod in an annular manner, and in this case the bypass valve is axially displaced to switch between the bypass position and the working position. In this way, the piston rod is used synergistically as a guide and thus to a certain extent as a component of the bypass valve. This simplifies the technical structure of the synchronous cylinder and reduces the susceptibility to errors.

Preferably, at least one of the bypass valves is or is pretensioned by means of a spring into the bypass position or the working position, particularly preferably into the bypass position. In principle, the bypass valve can be actuated in various ways, for example electrically, magnetically, hydraulically and / or mechanically. The bypass valve should, however, be controllable from the outside. Since the bypass valve is preloaded on one side, the structure is simplified, because active actuation only has to be implemented technically along the other direction. Particularly preferably, the bypass valve can be fixedly fixed in the working position so that it is not brought into the bypass position unintentionally, for example by the pressure in the pressure chamber. According to a particularly preferred embodiment, the spring for resetting or biasing the bypass valve is located on the inside, i. H. provided at least partially within the outer cylinder, preferably completely within the housing or completely within the synchronous cylinder closed on the head side by head sections.

Preferably, at least one of the bypass valves can be operated hydraulically in order to create a permanent technical solution that is not prone to faults. Particularly preferably, the preload is combined by a spring and the hydraulic solution. For the purpose of hydraulic actuation, the bypass valve is in contact with an actuation fluid, which is supplied via an actuation line, possibly with an actuation chamber, and a suitable connection on the synchronous cylinder.

The bypass device has two bypass valves which are provided on the opposite sides of the working piston. As a result, the bypass route via the annular gap and / or the at least one bypass line can be implemented in a technically simple manner. Particularly preferably, an essentially mirror-symmetrical structure of the bypass device, possibly of the entire synchronous cylinder, is used in order to homogenize the force properties. The bypass valve or valves are preferably provided at the end regions or the head sides of the synchronous cylinder, whereby the stroke is maximized. The Bypass valves, along with the piston surfaces and the inner cylinder, can provide part of the walls that form the pressure chambers.

The outer cylinder is preferably closed at its end sections with a cylinder lock. The inner cylinder is preferably fixed at its end sections relative to the outer cylinder by means of a cylinder head carrier. For this purpose, the inner cylinder is preferably made shorter in the axial direction than the outer cylinder. The terms "end side", "head side" and "front side" are used synonymously and mean the outer sections of the synchronous cylinder, seen in the axial direction.

A hydraulic fluid connection is preferably provided with a hydraulic fluid line which pierces the cylinder lock and / or the cylinder head support of the corresponding end side. The hydraulic fluid line with the hydraulic fluid connection is in fluid connection with the corresponding pressure chamber and supplies it with hydraulic fluid.

The cylinder head supports can be components which both contribute to the production and definition of the bypass device, preferably the annular gap, and which can also carry or contain the hydraulic fluid lines. As a further function, they can support the technical structure of the bypass valves, because the bypass valves are preferably in contact with both the piston rod and the corresponding cylinder head carrier. This simplifies the structure of the synchronous cylinder considerably and reduces its susceptibility to errors.

The two cylinder head supports preferably each have one or more bypass lines which establish a fluid connection between the pressure chambers and the annular gap and / or the at least one bypass line. In this case, the bypass valves in the working position preferably close the Fluid connection between the corresponding pressure chamber and the corresponding bypass line and open this fluid connection in the bypass position.

Although the invention is particularly preferred in the technical field of extrusion plants, the invention can also be implemented in other areas, for example in the area of rolling mills or generally devices for plastic deformation of hard workpieces, such as metal blocks or sheets. Further advantages and features of the present invention can be seen from the following description of preferred exemplary embodiments. The features described there can be implemented alone or in combination with one or more of the features set out above, provided the features do not contradict one another. The following description of the preferred exemplary embodiments takes place with reference to the accompanying drawings.

Brief description of the figures

• The Figure 1 shows the longitudinal section of a synchronous cylinder in a first embodiment of the invention.
• The Figure 2 shows a detail of a longitudinal section through a synchronous cylinder with a modified structure.
• The Figure 3 shows the installation position of a synchronous cylinder in the extrusion plant.
• The Figure 4 shows a further embodiment of the invention with an external bypass line.
• Figure 5 shows an embodiment not according to the invention with a large number of bypass lines integrated in the synchronous cylinder.

Detailed description of preferred exemplary embodiments

In the following, preferred embodiments are based on the Figure 1 described.

Identical, similar or identically acting elements are provided with identical reference symbols, and a repetitive description of these elements is in some cases dispensed with in order to avoid redundancies.

The Figure 1 shows a synchronous cylinder 1. More precisely, the two end sections of the cylinder 1 are shown in longitudinal section, which in the present exemplary embodiment are constructed essentially mirror-symmetrically.

The hydraulic cylinder 1 has a hollow outer cylinder 10, a hollow inner cylinder 20, a head section 30 on the left and right, and a piston rod 40 with an integrated or connected working piston 41. The head section 30 has a cylinder head carrier 31 and a cylinder lock 33, as a result of which the hydraulic cylinder 1 is closed at both ends and the inner cylinder 20 is fixed relative to the outer cylinder 10. The inner cylinder 20 is introduced into the outer cylinder 10, both are concentric with one another, so that an annular gap 51, which is part of a bypass device 50 described in detail later, is formed between the inner cylinder 20 and the outer cylinder 10. The working piston 41 is slidably mounted in the inner cylinder 20. The piston rod 40 extends on both sides of the working piston 41, pierces the respective head sections 30 and is thereby guided. Not described in detail, but in the Figure 1 Seals and parts, some of which are shown, for mounting the piston rod 40 and the working piston 41, which ensure problem-free operation of the hydraulic cylinder 1, can be provided at suitable locations.

Left and right of the working piston 41 are pressure chambers 42, which are surrounded by the working piston 41, the inner cylinder 20 and head-side components such as a cylinder head support 31 and a bypass valve 52 described later and are defined thereby. The working piston 41 is acted upon from both sides by a pressure medium or hydraulic fluid - for example a hydraulic oil - which is located in the pressure chambers 42. The hydraulic fluid is fed into the pressure chambers 42 via bores or lines, referred to here as hydraulic fluid lines 32. The hydraulic fluid lines 32 extend through the two head sections 30. The hydraulic fluid lines 32 can have a hydraulic fluid connection 32 ′, a hydraulic fluid ring line 32 ″ and other components which are suitable for safely supplying the pressurized hydraulic fluid to the pressure chambers 42 , to distribute and derive, have or be fluidically connected to it.

A pressure difference in the hydraulic fluid between the two pressure chambers 42 causes a force on the working piston 41, which can lead to a displacement of the working piston 41 in the axial direction and thus the piston rod 40. For this purpose, hydraulic fluid flows into one of the two pressure chambers 42 via the relevant hydraulic fluid line 32, and the hydraulic fluid is displaced in the other pressure chamber 42, hydraulic fluid being discharged via the other hydraulic fluid line 32. Since the area of application of the working piston 41 is of the same size on both sides, the hydraulic cylinder 1 acts as a synchronous cylinder, which is also referred to as a synchronous cylinder. This operating mode is referred to as the working mode, in order to distinguish it from a drag operating mode, described below, which enables the working piston 41 to be displaced without pressure or with little pressure.

For the rapid, pressureless movement of the working piston 41 - for example for setting or adjusting a transducer in an extrusion press - the hydraulic cylinder 1 has a bypass device 50. In the present exemplary embodiment, this includes the annular gap 51, the two bypass valves 52, bypass lines 53 which are in fluid connection with the annular gap 51, and actuating devices 54. The two bypass valves 52 are guided on the piston rod 40 in the area of the two head sections 30 and open and close the bypass lines 53 in that they are actuated, ie displaced, in the axial direction by the actuating device 54. When the bypass valve 52 is open, the hydraulic fluid can pass from the relevant hydraulic chamber 42 into the nearby bypass line 53, from there the hydraulic fluid enters the annular gap 51. When both bypass valves 52 are open, the working piston 41 can be displaced without force or with little force in this way, since there is a fluid connection between the two pressure chambers 42 via the bypass lines 53 and the annular gap 51. Due to its external arrangement and annular shape, the annular gap 51 enables particularly optimal behavior in terms of flow.

The actuation of the bypass valves 52 takes place via the actuating devices 54. In the present exemplary embodiment, these have an actuating rod 54 'pretensioned by a spring, which extends through the relevant head section 30 and is connected to the bypass valve 52, and an actuating hydraulic section 54 "with an actuating connection 54 '' ', a bore and a chamber (without reference numerals). By preloading the bypass valve 52, here for example by means of the spring, the bypass valve 52 is automatically brought into a preferred position Actuating hydraulic section 54 ″ is introduced or discharged, the actuating valve 52 is actuated.

The bypass device 50 for moving the working piston 41 without pressure or with low pressure is implemented by means of the above-described annular gap 51, which leads around the working piston 41 on the outside through the concentric hollow cylinders 10 and 20. This technical solution is space-saving and with regard to the flow conditions excellent, because the annular gap 51 has the lowest flow losses compared to other solutions. The concentric, ring-shaped bypass valves 52 shown here as an example and guided on the piston rod 40 allow the operating modes of the hydraulic cylinder 1 to be switched quickly and safely. A targeted control of the overflow of the hydraulic fluid between the two pressure chambers 42 or from the annular gap 51 into the pressure chambers 42 is implemented in a technically simple, error-free and long-lasting way. Furthermore, the technical solution shown here has a small number of hydraulic connections, which further simplifies the operation of the hydraulic cylinder 1.

The Figure 2 shows a modified structure with respect to the actuating device 54. For the purpose of illustration, only a section of the longitudinal section through the synchronous cylinder 1 is shown, but this can - as in FIG Figure 1 - Be constructed essentially mirror-symmetrically.

In contrast to the synchronous cylinder of the Figure 1 the actuating device 54 for actuating the bypass valves 52 does not have an actuating rod 54 'with an external return spring, but the return or pretensioning of the bypass valve 52 takes place via an internal spring 55. The actuating hydraulic section 54 "with the actuating connection 54'"'are essentially unchanged The end of the actuation hydraulic section 54 ″, which is opposite the actuation connection 54 ″ ″, is an annular chamber (but without reference symbols in FIG Figure 2 clearly visible) is provided, which is adjacent to one side of the bypass valve 52. The bypass valve 52 is actuated as in the exemplary embodiment in FIG Figure 1 ; d ,. H. by biasing the bypass valve 52, here according to FIG Figure 2 by means of the internal spring 55, the bypass valve 52 is automatically brought into a delayed position. The actuation valve 52 is actuated by a fluid being introduced into or drained off into the actuation hydraulic section 54 "via the actuation connection 54 '"'.

Due to the slim design, the synchronous cylinder 1 can be guided through a cylinder spar of an extrusion plant. For this reason, the hydraulic cylinder is 1 can be used particularly preferably in the field of extrusion plants, in particular for implementing the transducer kinematics, including the force function. It has the great advantage that it can be switched from towing to working mode over the entire stroke thanks to the pressure-free adjustment. The synchronous cylinder 1 is thus able to support any electric motors in all positions for rapid movement over the entire stroke with the full cylinder power.

The installation position of the synchronous cylinder 1 in an extrusion plant 100 is shown in FIG Figure 3 shown. The synchronous cylinder 1, its structure in the Figure 3 less detailed than shown in the previous figures, is guided by a cylinder spar 101. One side of the piston rod 40 is connected to a pickup 102 which can be moved via the synchronous cylinder 1, for example between a position for changing blocks and a front end position, the working position at which the pressing, venting and stripping takes place. Alternatively, the pickup 102 can be moved by one or more electric motors, not shown, which move the pickup 102 between the block change position and the working position. The synchronous cylinder 1 is moved externally. For such an external movement, that is to say for rapid, pressureless actuation of the synchronous cylinder 1, this is switched to the towing mode in the manner described above.

Figure 4 shows an alternative embodiment of a synchronous cylinder 1 according to the invention, in which, unlike in the first embodiment according to FIGS Figures 1 to 3 a bypass device 50 in the form of a bypass line 103 is arranged outside the housing and connects the pressure chambers 42 to one another via respective bypass valves 52. The bypass line 103 replaces the annular gap between the outer cylinder 10 and the inner cylinder 20 according to the embodiments of FIG Figures 1 to 3 . The bypass line 103, however, has the same technical effects as the annular gap 51 according to the embodiments of FIG Figures 1 to 3 .

The Figure 5 shows an embodiment of a synchronous cylinder 1 not according to the invention in a side view and one along the line AA from Figure 5 sectioned frontal view. From the front view according to Figure 5b it can be seen that four bypass lines 103a-d are arranged inside the housing of the synchronous cylinder 1 outside the outer cylinder 10. These bypass lines 103a-d replace the bypass line 103 according to FIG Figure 4 in its entirety the annular gap 51 according to the embodiments of FIG Figures 1 to 3 . The bypass lines 103a-d connect in the same way as the bypass line 103 according to FIG Figure 4 the pressure chambers 42 of the synchronous cylinder 1.

Not all of the technical features presented in the context of the exemplary embodiments have to be essential for the invention. For example, the inflow and outflow between the annular gap 51 and the pressure chambers 42 can be implemented differently than by means of the bypass lines 53 shown here. The bypass valves 52 can also be constructed and / or positioned differently, although the technical solution presented is preferred.

List of reference symbols

1

Synchronous cylinder

10

Outer cylinder

20th

Inner cylinder

30th

Head section

31

Cylinder head carrier

32

Hydraulic fluid line

32 '

Hydraulic fluid connection

32 "

Hydraulic fluid ring line

33

Cylinder lock

40

Piston rod

41

Working piston

42

Pressure chambers

50

Bypass device

51

Annular gap

52

Bypass valve

53

Bypass line

54

Actuator

54 '

Operating rod

54 "

Actuation hydraulic section

54 '' '

Actuation connection

55

Spring to preload the bypass valve

100

Extrusion line

101

Cylinder spar

102

Transducer

103

Bypass line

Claims (11)

1. Synchronous cylinder (1), preferably for an extruder, comprising an outer cylinder (10), an inner cylinder (20) installed therein and arranged concentrically therewith, a double-acting work piston (41) provided in the inner cylinder to be displaceable and a bypass device (50) with at least one bypass valve (52), wherein the work piston (41) divides the inner cylinder (20) into two pressure chambers (412) and can be loaded with a hydraulic fluid from both pressure chambers (42), wherein the bypass device (50) is so arranged that in a bypass setting of the bypass valve (52) a fluid connection between the two pressure chambers (42) is produced by way of a direct connection, preferably at least one bypass line, and in a work setting of the bypass valve (52) no such fluid connection is present, characterised in that the bypass device (50) comprises two bypass valves (50) respectively provided on opposite sides of the work piston (41).
2. Synchronous cylinder (1) according to claim 1, characterised in that the direct connection, preferably the bypass line, is arranged between the outer cylinder and the inner cylinder of the synchronous cylinder (1).
3. Synchronous cylinder (1) according to one of claims 1 and 2, characterised in that the bypass line is arranged outside the synchronous cylinder housing.
4. Synchronous cylinder (1) according to any one of the preceding claims, characterised in that at least one of the bypass valves (52) is biased by means of spring (55) into the bypass setting or the work setting, preferably the bypass setting.
5. Synchronous cylinder (1) according to claim 4, characterised in that the spring (55) for resetting or biasing the bypass valve (52) is provided partly or completely in the outer cylinder, preferably completely within the synchronous cylinder (1) closed at the head side by head sections (30).
6. Synchronous cylinder (1) according to any one of the preceding claims, characterised in that at least one of the bypass valves (52) is hydraulically actuable.
7. Synchronous cylinder (1) according to any one of the preceding claims, characterised in that the outer cylinder (10) is closed at each of its end sections by a respective cylinder closure (33), the inner cylinder (20) is fixed at each of its end sections relative to the outer cylinder (10) by means of a respective cylinder head support (31), and a respective hydraulic fluid connection (32') and hydraulic fluid line (32), which are formed in the cylinder closure (33) and/or cylinder head support (31) of the corresponding side, are provided at each of the two ends.
8. Synchronous cylinder (1) according to claim 7, characterised in that the two cylinder head supports (31) each have one or more bypass ducts (53) producing a fluid connection between the pressure chambers (42) and the annular gap (51).
9. Synchronous cylinder (1) according to any one of the preceding claims, characterised in that the bypass valves (52) are in contact not only with the piston rod (40), but also with the corresponding cylinder head support (31) and in the work setting close and in the bypass setting open the fluid connection between the corresponding pressure chamber (42) and the corresponding bypass duct (53).
10. Reshaping device, preferably press, extruder or ring roller, with one or more synchronous cylinders (1) according to any one of the preceding claims.
11. Reshaping device according to claim 10, characterised in that one or more electric motors are provided for adjusting the synchronous cylinder (1).

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