WO1996041957A1 - Hydraulic pressure boosting unit, in particular for a press operating according to the high inner pressure extrusion process - Google Patents

Abstract

A known hydraulic pressure boosting unit has a pressure booster (11) with a primary piston (40) that slides axially in a first cylinder chamber (16), a secondary piston (41) located on one first side of the primary piston (40) and that plunges into a high pressure chamber (28) and a piston rod (42) located at the second side of the primary piston (40) that extends into a second cylinder chamber (44) separated from the first cylinder chamber (16). A hydraulic fluid may be supplied from an outer connection to the high pressure chamber (44) through the second cylinder chamber (44) and an axial channel (49) that extends longitudinally through the piston rod (42), primary piston (40) and the secondary piston (41). Besides the pressure booster (11), the unit has a fast motion cylinder (12) whose fast motion piston (45) is linked to the piston rod (42) of the pressure booster (11). In order to obtain a hydraulic pressure boosting unit having a short length, the fast motion piston is located in the second cylinder chamber (44) which is divided into a piston rod-side partial chamber (44a) and into a piston rod-opposite side partial chamber (44b). A first hydraulic fluid channel (48) opens into the piston rod-side partial chamber (44a) and a second hydraulic fluid channel opens into the piston rod-opposite side partial chamber (44b). The axial channel (49) is open towards the piston rod-side partial chamber (44a).

Description

description

Hydraulic pressure intensifier unit, in particular for a press working according to the internal high pressure molding process

The invention is based on a hydraulic pressure intensifier unit, which is used in particular on a press working according to the internal high pressure forming method and which has the features from the preamble of claim 1.

Such a hydraulic pressure intensifier unit is known from DE 43 12 589 AI. In the pressure intensifier unit from this document, the primary piston of the pressure intensifier is axially displaceable in a first cylinder space, while the secondary piston, which is located on a first side of the primary piston, is immersed in a high pressure space. A piston rod extends from the second side of the primary piston opposite the secondary piston, which passes through a housing head that closes the first cylinder chamber, a second cylinder chamber that is separate from the first cylinder chamber, and a cover that closes the second cylinder chamber and projects above the second cylinder chamber The cylinder chamber can be supplied with hydraulic fluid through an axial channel running centrally through the piston rod, the primary piston and the secondary piston of the pressure intensifier, in order to fill the blank to be deformed. The axial channel and the second cylinder chamber are connected to one another via a transverse bore in the piston rod. So that this transverse bore does not get into the area of seals between the first and the second cylinder space, the length of the second cylinder space is greater than the maximum stroke of the piston rod.

The primary piston, secondary piston and piston rod of the pressure converter can also be moved in rapid traverse. For this purpose, in a version shown in DE 43 12 589 AI, a completely separate rapid traverse cylinder with a rapid traverse piston and with a rapid traverse piston rod is provided, which with that from the second Cylinder chamber protruding piston rod of the pressure intensifier is connected. In another embodiment from DE 43 12 589 AI, the piston rod of the pressure intensifier itself forms the housing of the rapid traverse cylinder, which is displaceable relative to a stationary rapid traverse piston. The known hydraulic pressure intensifier units with rapid traverse cylinders are relatively long axially.

The aim of the invention is to further develop a hydraulic pressure intensifier unit with the features from the preamble of claim 1 in such a way that smaller axial dimensions are possible.

This object is achieved according to the invention in that in a hydraulic pressure intensifier unit with the features from the preamble of claim 1 according to the characterizing part of this claim, the rapid-motion piston is located in the second cylinder space and divides it into a piston rod-side subspace un into a piston rod-side subspace that in the piston rod-side compartment a first pressure medium channel un opens into the piston rod-side compartment a second pressure medium channel and that the axial channel is open to the piston rod-side compartment. In this way, the matched to the maximum stroke of the pressure intensifier length of the second cylinder space is also used for the stroke of the rapid traverse piston, s that compared to the known hydraulic pressure intensifier units, the axial length can be significantly reduced without the supply of pressure medium through the axial channel in front of the face of the secondary piston would be more difficult. It is also advantageous that the piston rod of the pressure intensifier does not have to be guided outward from the second cylinder space, which would lead to additional sealing problems.

Advantageous embodiments of a hydraulic pressure booster unit according to the invention can be taken from the subclaims. In the case of a hydraulic pressure booster unit of the type according to the invention, a hydraulic oil is used as the pressure medium with which the primary piston of the pressure booster is applied. A water-based hydraulic fluid, a so-called HFA fluid, is used as the pressure medium in which the internal high pressure required to deform a blank is generated. Advantageously, the two partial spaces on the two sides of the rapid traverse piston can now be acted upon with the same pressure fluid. If an HFA liquid is the pressure medium with which a blank is deformed, the rapid traverse piston is also pressurized with this HFA liquid on the side facing away from the piston rod. No HFA liquid can get into the hydraulic oil and no hydraulic oil can get into the HFA liquid via the rapid traverse piston.

So that the rapid traverse piston can exert a large force, it is advantageous if, according to claim 3, the sub-space on the piston rod side is relieved of pressure when the sub-space on the piston rod side is pressurized.

For the piston rod-side part space, the maximum pressure is set to a value which has proven to be favorable for filling the blank to be formed. This maximum pressure is in the range between 30 and 70 bar. According to claim 4, the piston rod-side subspace can preferably be subjected to a higher pressure than the piston rod-side pressure chamber in order to be able to move the primary piston and the secondary piston of the pressure intensifier in rapid traverse.

If there is a displacement sensor with which the stroke of the pressure booster is to be monitored, the hydraulic pressure booster unit is advantageously developed in accordance with claim 5. The displacement sensor is then arranged so that it does not enlarge the axial dimensions of the pressure intensifier unit.

An embodiment of a hydraulic pressure intensifier unit according to the invention is shown schematically in the drawing. The invention will now be explained in more detail with reference to this drawing.

The hydraulic pressure intensifier unit shown comprises a docking cylinder 10, a pressure intensifier 11 and a rapid traverse cylinder 12 for the pressure intensifier 11. The parts named with regard to their function cannot be clearly separated from one another locally, but are integrated into one another to form a compact unit. The housing 13 of the unit includes a docking cylinder 10 and the pressure intensifier 11 common, a one-piece housing middle part 14, which has a third cylinder wall 15 and a first cylinder space 16. The two cylinder spaces 15 and 16 are open on opposite sides and separated from one another by a bottom 17 of the housing middle part 14, from which the cylinder jackets 18 and 19 extend in opposite directions in the cylinder spaces. The third cylinder space 15 is provided with a housing head 20 and de first cylinder chamber 16 closed with a housing head 21.

The third cylinder chamber 15 belongs to the docking cylinder 10. A docking piston 25 is axially displaceable in it and has a piston rod attached to it only on one side. This passes al docking piston rod 26 through the housing head 20 to the outside. A its free end is screwed on a flange 27, with which egg-shaped tubular blank 37 can be closed. A central bore 28 extends axially through the Andoc piston 25 and through the docking piston rod 26, this bore weaving a section 29 with a smaller diameter and has a section 30 with a larger diameter, the latter extends from the end face of the docking piston rod 26 facing the flange 27 to a radial shoulder 3 which has an axial distance from the housing head 20 even when the docking piston rod 26 is retracted to the maximum. Docking piston rod 26 and housing head 20 are sealed off from one another with the aid of two axially spaced seals 32 and 33, between which a leak line 34 extends.

Through two connections 35 and 36 through the cylinder jacket 18, hydraulic oil can flow into or out of the two partial spaces 15a and 15b of the cylinder space 15 separated from one another by the docking piston 25.

The primary piston 40 of the pressure booster 11, which divides the cylinder space 16 into the two partial spaces 16a and 16b, is displaceable in the first cylinder space 16. The secondary piston 41 of the pressure intensifier 11, which has a much smaller diameter than the primary piston 40, projects from one side of the primary piston 40 like a piston rod, passes through the bottom 17 of the middle housing part 14 and dips into the central bore 28 of the docking piston 25 and the docking piston rod 26 reaching into the bore section 30. The step 31 in the bore 28 is not overrun by the free end of the docking piston rod 26 in any phase of a working cycle of the pressure booster unit. The free end of the secondary piston 41 is therefore always axially outside the housing head 20.

On the primary piston 40 of the pressure intensifier 11, in addition to the secondary piston 41, a piston rod 42 which is opposite to the secondary piston 41 is fastened and passes through a bore 43 in the housing head 21 into a second cylinder formed with the aid of this housing head and a housing pot 22 the space 44 occurs and there is firmly connected to a rapid-motion piston 45. The rapid-motion piston 45 divides the cylinder space 44 into two partial spaces 44a and 44b, each of which can be supplied with a pressure fluid via a channel 47 or 48 in the housing pot 22. A water-based hydraulic fluid (HFA fluid) is intended for this. A channel 49 leads centrally through the piston rod 42, the primary piston 40 and the secondary piston 41 of the pressure intensifier 11 and is supplied through a transverse bore 50 with the pressure fluid via the channel 48. th partial chamber 44a of the cylinder chamber 44 is connected and at the mouth of which in the section 30 of the bore 28 there is a check valve 51 blocking the channel 48.

The primary piston 40 of the pressure booster 11 can be alternately pressurized on both sides via the channels 52 and 53 passing through the cylinder jacket 19. Hydraulic oil is used as the pressure medium.

A number of seals are provided to separate the various pressure chambers and the various hydraulic fluids from one another. In the bore 43, three axially spaced seals 60, 61 and 62 are arranged between the housing head 21 and the piston rod 42. Between the seals 60 and 61 there is a leakage line 63, in which water-based hydraulic fluid leaking from the part space 44a of the cylinder space 44 is discharged via the seal 60. Between the seals 61 and 62 there is a leakage line 64, via which the hydraulic oil leaks out of the partial space 16a of the cylinder space 16 via the seal 62.

In the bottom 17 of the housing middle part 14 between the secondary piston 41 of the pressure intensifier and the bottom, two seals 65 and 66 are arranged at an axial distance from one another, between which a leak line 67 comes off, which is connected to the tank as is usual with a leak and which a mutual influence of the pressures in the two sub-spaces 15a and 16b of the cylinder spaces 1 and 16, which are separated from one another by the base 17, is prevented.

Between the sub-chamber 15 a with hydraulic oil, which can be acted upon by hydraulic oil, the cylinder chamber 15 and the section 30 of the bore 28, which can be struck with hydraulic fluid based on water, three seals are again effective, which are in the section 29 of the bore 28 between the docking piston 25 and the docking piston rod 26 on the one hand and the secondary piston 4 on the other hand are fixedly arranged relative to the docking piston and to the docking piston rod. The seal 68 is located immediately behind the piston-side start of the bore 28 in the docking piston 25. The other two seals 69 and 70 are located just before the step 31 in radial planes, which also extend in front of the housing head 20 when the docking piston rod is retracted completely. The seals recognizable in FIG. 1 can each be composed of a plurality of sealing rings, which are also axially spaced apart.

Between the two seals 69 and 70, a leakage line 71 for the hydraulic fluid, which leaks from section 30 of the bore 28 via seal 70, leads through the docking piston rod 26 to the outside. Another leakage line 72 is also still in each position of the docking piston rod 26 in front of the housing head 20, passes transversely through the docking piston rod 26 and opens into the section 29 of the bore 28 between the two seals 68 and 69 Hydraulic oil discharged that leaks through the seal 68.

The HFA liquid is fed to the two channels 47 and 48 via a control block 80, which has a pump connection 81 connected to a pump 79 and a tank connection 82 and to which various valves are attached. One of these valves is a 4/2-way valve 83 which is connected to the tank connection 82 with a valve connection A and to the pump connection 81 of the control block 80 with a valve connection B. A channel 85 leads from a valve connection P of the directional control valve 83 to an output 86 of the control block 80, to which the channel 47 is connected. Another port T of the directional valve 83 is connected to a port A of a 3/2-way seat valve 87. In the switching position of the directional control valve 83 shown in the drawing, its connections A and P as well as B and T are connected to one another. In the other switching position there is a connection between the connections A and T and the connections B and P.

In the position shown, the 3/2-way seat valve 87 switches through the connection A to a connection T, which connects directly to the tank connection 82 of the control block 80 and, via a check valve 88 opening towards it, to the leak line 63 is. In the other switching position of the 3/2-way seat valve 87, the connection A is connected to a connection P, which is located at an output 89 of the control block 80, to which the channel 48 is connected.

The maximum pressure at port P of the 3/2-way seat valve 87 is determined by a pressure relief valve 90, which may be set to a value of approximately 50 to 60. The maximum pressure at the port P of the 4/2-way valve 83 is determined by a pressure limiting valve 91 which is set to a higher maximum pressure than the pressure limiting valve 90, for example 110 bar. Hydraulic fluid can be sucked in from the tank connection 82 of the control block into the two partial spaces of the cylinder space 44 via suction valves 92.

In the state shown in the drawing, the HFA liquid is circulated by the pump 79 via the pump connection 81 of the control block 80, the 4/2-way valve 83, the 3/2-way seat valve 87 and the tank connection 82 of the control block 80 promoted in circulation. At the beginning of a working cycle, the docking piston 25 first pushes the flange 27 close to the blank 37 to be deformed. The 3/2-way seat valve is switched so that HFA liquid from the pump connection 81 of the control block 80, via the directional valve 83, the 3/2-way valve 87, the channel 48, the partial area 44a of the cylinder space 44, the transverse bore 50, the longitudinal bore 49, the check valve 51, the section 30 of the bore 28 and a bore 75 in the flange 27 are conveyed into the blank, where the air escapes from the blank through a gap between the flange and the blank together with HFA liquid. The pressure in the blank increases. At the pressure set at the pressure relief valve 90, the blank is considered filled and is closed by the docking cylinder. Now the two way valves 83 and 87 are switched. This relieves on the one hand the piston rod-side part 44a of the cylinder chamber 44 to the tank, where the check valve 51 prevents backflow of liquid from the Rohlin and on the other hand the piston rod-side part 44b of the cylinder chamber 44 via the directional valve 83 with the pumps connection 81 of the control block 80 connected. The rapid traverse piston 45 pushes the secondary piston 41 of the pressure intensifier 11 deeper into the bore 28. Since the pressure set at the pressure limiting valve 91 in the subspace away from the piston rod cannot be exceeded, the rapid-motion piston 45 can be used to move the secondary piston 41 only up to a certain pressure level in the blank to be formed. From this pressure, in addition to the rapid-motion piston 45, the primary piston 40 of the pressure booster 11 is pressurized via the channel 52.

During the deformation of the blank 37, the docking piston 25 can be moved further in order to axially feed material of the blank.

After the forming process has ended, the liquid in the formed blank is first decompressed by partially withdrawing the primary piston 40 and the secondary piston 41 of the pressure intensifier 11 together with the rapid-motion piston 45, and then the docking piston 25 is brought back into the starting position shown in the drawing.

During a work cycle, the path of primary piston 40 and secondary piston 41 is monitored by a displacement sensor 95, which is arranged decentrally in the area of housing pot 22 and housing head 21 without increasing the axial dimensions of the pressure booster unit. The displacement sensor is rod-shaped and has a first part 96, which is fixed in place on the housing pot 22, and a rod 97, which is fastened to the primary piston 40 and is tightly guided through the housing head 21 as a second part. The rod carries at its free end an annular permanent magnet, not shown, which is displaced along a rod 98 of the first part 96 when the primary piston 40 moves. Depending on the position of the permanent magnet relative to the rod 98, the displacement sensor 95 emits a different signal.

Claims

claims 1. Hydraulic pressure intensifier unit, in particular for a press working according to the internal high-pressure method, with a pressure intensifier (11), which has a primary piston (40), which is axially displaceable in a first cylinder space (16), a secondary piston (41), which located on a first side of the primary piston (40) and immersed in a high pressure space (28), and a second cylinder space extending from the second side of the primary piston (40) into a second cylinder space separated from the first cylinder space (16) (44) reaching piston rod (42), with a pressure fluid via the second cylinder chamber (44) and an axial channel (49) extending longitudinally through the piston rod (42), the primary piston (40) and the secondary piston (41) can be fed to the high-pressure chamber (28), and is characterized by a rapid traverse cylinder (12), the rapid traverse piston (45) of which is connected to the piston rod (42) of the pressure intensifier (11), characterized in that the rapid traverse piston (45) is located in the second cylinder chamber (44) and divides it into a piston rod-side compartment (44a) and a piston rod-side compartment (46b) that a first pressure medium channel (48) in the piston rod-side compartment (44a) and in the piston rod-side compartment ( 44b) a second pressure medium channel (47) opens out and that the axial channel (49) is open towards the part-rag (44a) on the piston rod side. 2. Hydraulic pressure intensifier unit according to claim 1, characterized in that the two sub-spaces (44a, 44b) on the two sides of the rapid traverse piston (45) are acted upon by the same pressure liquid. 3. Hydraulic pressure intensifier unit according to claim 1 or 2, characterized in that the piston rod-side part roughness (44a) is relieved of pressure during a pressurization of the piston rod-side subspace (44b). 4. Hydraulic pressure intensifier unit according to a preceding claim, characterized in that the piston rod side subspace (44b) can be acted upon with a higher maximum pressure than the piston rod side subspace (44a). 5. Hydraulic pressure intensifier unit according to a preceding claim, characterized by an axially extending, rod-shaped displacement sensor (95) which extends decentrally through a housing head (21) closing the piston rod side on the piston rod side and which is stationary arranged first part (96) and a second part (97) attached to the primary piston (40) of the pressure booster (11).