METHOD FOR OPERATING A HYDRAULICALLY OPERATED HAND-HELD DEVICE AND HYDRAULICALLY OPERATED HAND-HELD DEVICE

Abstract

A method for operating a hydraulically operated hand-held device is provided. The hand-held device includes a hydraulic pump, a moving part, a fixed part and a return valve with an associated valve seat. The moving part can be displaced into a working position by a build-up of hydraulic pressure produced by filling a hydraulic chamber with hydraulic medium from a storage chamber using the hydraulic pump. The moving part can be automatically moved back from the working position into an end position by opening the return valve, if a predetermined working pressure is reached. The hydraulic pressure acting upon the return valve for triggering a movement of the moving part into the end position is increased independently of reaching the predefined working pressure.

Claims

1. A method for operating a hydraulically operated hand-held device (1), for example a pressing device and/or a hole-punching or punching device, wherein the hand-held device (1) comprises a hydraulic pump, a moving part (4), a fixed part (5) and a return valve (8) with an associated valve seat, wherein furthermore the moving part (4) is displaced into a working position by build-up of hydraulic pressure which is produced by filling a hydraulic chamber (6) with hydraulic medium from a storage chamber (3) using the hydraulic pump, and the moving part (4) is automatically moved back from the working position into an end position by an opening of the return valve (8) when a predefined working pressure is reached, characterized in that the hydraulic pressure acting on the return valve (8) is increased to trigger a movement of the moving part (4) into the end position independently of reaching the predefined working pressure, wherein an initial type of pressure increase moves a piston of the return valve from a valve seat, whereafter a return opening for the hydraulic medium is released and the returning hydraulic medium acts upon an enlarged total piston surface of the return valve compared with a partial piston surface and thus holds the return valve in the open position even with reduced pressure or decreasing pressure.

2. The method according to claim 1, characterized in that the area which the partial piston surface adds to the total piston surface can also be acted upon by hydraulic medium in the closure state of the return valve.

3. The method according to claim 2, characterized in that the pressure increase is accomplished in the hydraulic medium which acts on the surface of the return valve which adds the partial piston surface to the total piston surface when the return valve is open.

4. The method according to any one of the preceding claims, characterized in that the return valve (8) is opened automatically at a modified working pressure compared with the predefined working pressure.

5. The method according to claim 4, characterized in that the modified working pressure can be set.

6. The method according to any one of the preceding claims, characterized in that the increase in the hydraulic pressure is accomplished by supplying hydraulic medium into a given chamber (26) downstream of the valve seat with a view to the drain direction of the hydraulic medium.

7. The method according to any one of claims 1 to 5, characterized in that the pressure increase is carried out by reducing the space (26) given after the valve seat.

8. The method according to any one of claims 6 or 7, characterized in that the space (26) given after the valve seat before an opening of the return valve is given on the one hand by the total piston surface minus the partial piston surface and on the other hand by the surface of the valve seat facing the total piston surface minus the partial piston surface including a delimiting surface of the pressure-increasing piston and optionally a surface of a line section given in this connection.

9. The method according to any one of the preceding claims, characterized in that the increase in the hydraulic pressure is accomplished by a movement of a pressure-increasing piston (22).

10. The method according to claim 9, characterized in that the pressure-increasing piston (22) is moved into a hydraulic medium cylinder (21).

11. The method according to claim 10, characterized in that the hydraulic medium cylinder (21) is continuously connected to a return line (7) of the hydraulic medium.

12. The method according to claim 10, characterized in that the hydraulic medium cylinder (21) is only hydraulically in communication with the return line (7) of the hydraulic medium when the return valve is open.

13. The method according to any one of claims 9 to 12, characterized in that the pressure-increasing piston (22) is moved via a separate drive from a drive of the hydraulic pump.

14. The method according to any one of claims 9 to 13, characterized in that the pressure-increasing piston (22) is moved by means of an adjusting magnet (23).

15. A hydraulically operated hand-held device (1), for example a pressing device and/or a hole-punching or punching device, wherein the hand-held device (1) comprises a hydraulic pump, a moving part (4), a fixed part (5) and a return valve (8) with an associated valve seat, wherein furthermore the moving part (4) can be displaced into a working position by build-up of hydraulic pressure which is produced by filling a hydraulic chamber (6) with hydraulic medium from a storage chamber (3) using the hydraulic pump, wherein it can be achieved that the moving part (4) is automatically moved back from the working position into an end position by an opening of the return valve (8) when a predefined working pressure is reached, wherein further a pressure sensor (29) is provided, wherein a return of the moving part (4) can be accomplished depending on a pressure value measured by the pressure sensor (29) by a triggerable opening of the return valve (8), and the working pressure at which the opening of the return valve (8) is triggered can be selected to be different from the predefined working pressure, characterized in that an adjusting device (27) for different working pressures which can be present by the user is provided on the hand-held device, configured as an adjusting wheel, adjusting slider, an arrangement of a multiplicity of buttons, wherein each button is assigned a predefined working pressure or as a keyboard with a relevant display, wherein the actually selected working pressure is reproduced on the display, that an evaluation/control electronics evaluates pressure measured values of the pressure sensor (29) in the course of the movement of the moving part (4) in the direction of the working position and compares these with the desired pressure value predefined via a button (28) and that the working pressure can be set additionally via a non-mechanical interface, in particular a radio and/or optical interface to the device.

16. The hand-held device according to claim 15, characterized in that the pressure sensor continuously makes a pressure measurement at specific time intervals when the device is switched on.

17. The hand-held device according to claim 16, characterized in that the time intervals are given in the range of one or several milliseconds, for example, in the range between 1 and 200 milliseconds.

18. A method for operating a hydraulically operated hand-held device (1), for example a pressing device and/or a hole-punching or punching device, wherein the hand-held device (1) comprises a hydraulic pump, a moving part (4), a fixed part (5) and a return valve (8) with an associated valve seat, wherein furthermore the moving part (4) is displaced into a working position by build-up of hydraulic pressure which is produced by filling a hydraulic chamber (6) with hydraulic medium from a storage chamber (3) using the hydraulic pump, and the moving part (4) is automatically moved back from the working position into an end position by an opening of the return valve (8) when a predefined working pressure is reached, wherein further a working sequence is triggered by actuation of a switch (9) or a button by a hand of a user and upon cancellation of the actuation of the switch or button by the user, at the same time an opening of the return valve and a return of the moving part (4) are triggered, characterized in that the return of the moving part (4) is only accomplished by a cancellation of the actuation if a first workpiece contact has been determined previously on the device side.

19. A hydraulically operated hand-held device (1), for example a pressing device and/or a hole-punching or punching device, wherein the hand-held device (1) comprises a hydraulic pump, a moving part (4), a fixed part (5) and a return valve (8) with an associated valve seat, wherein furthermore the moving part (4) can be displaced into a working position by build-up of hydraulic pressure which is produced by filling a hydraulic chamber (6) with hydraulic medium from a storage chamber (3) using the hydraulic pump, wherein it can be achieved that the moving part (4) is automatically moved back from the working position into an end position by an opening of the return valve (8) when a predefined working pressure is reached, characterized in that the hydraulic pressure acting on the return valve (8) can be increased independently of reaching the predefined working pressure to a pressure value which brings about an opening of the return valve (8), wherein the pressure increase is of an initial type and moves a piston of the return valve from a valve seat for release of a return opening for the hydraulic medium, wherein further the returning hydraulic medium can act upon an enlarged total piston surface of the return valve compared with a partial piston surface and thus can keep the return valve in the open position even with reduced pressure or decreasing pressure.

20. The hand-held device according to claim 19, characterized in that a movable pressure-increasing piston (22) is provided to increase the pressure.

21. The hand-held device according to any one of claims 19 or 20, characterized in that the pressure-increasing piston (22) is movable in a hydraulic cylinder (21).

22. The hand-held device according to claim 19, characterized in that the hydraulic medium cylinder (21) is continuously hydraulically in communication with a return line (7) of the hydraulic medium.

23. The hand-held device according to claim 21, characterized in that the hydraulic medium cylinder (21) is only hydraulically in communication with the return line (7) of the hydraulic medium when the return valve is open.

24. The hand-held device according to any one of claims 20 to 23, characterized in that the pressure-increasing piston (22) is movable by means of a drive separate from a drive of the hydraulic pump.

25. The hand-held device according to claim 24, characterized in that the pressure-increasing piston (22) is movable by means of an adjusting magnet (23).

26. The hand-held device according to claim 25, characterized in that the hydraulic volume which can be used to increase the pressure value on the return valve (8) is in communication with the hydraulic storage chamber (3) via a check valve (30).

27. The hand-held device according to any one of claims to 2 to 26, characterized in that the area which the partial piston surface adds to the total piston surface can also be acted upon by hydraulic medium in the closure state of the return valve.

28. The hand-held device according to any one of claims 19 to 27, characterized in that the pressure is increased in the hydraulic medium which acts upon the area of the return valve which, when the return valve is open, the partial piston surface adds to the total piston surface.

29. The hand-held device according to any one of claims 19 to 28, characterized in that the pressure increase can be accomplished by means of a reduction in the size of the space (26) given downstream of the valve seat.

30. The method according to claim 29, characterized in that the space (26) given downstream of the valve seat upstream of an opening of the return valve is given on the one hand by the total piston surface minus the partial piston surface and on the other hand by the area of the valve seat facing the total piston surface minus the partial piston surface including a delimiting surface of the pressure-increasing piston and optionally a surface of a line section given in this connection.

Description

[0056] The invention is explained hereinafter with reference to the appended drawings which merely show one exemplary embodiment. In the drawings:

[0057] FIG. 1 shows an overall view of a hydraulically operated hand-held device in the form of a pressing device;

[0058] FIG. 2 shows the enlarged section according to the line II-II in FIG. 1;

[0059] FIG. 3 shows an enlargement of the region III in FIG. 2;

[0060] FIG. 4 shows a diagram corresponding to FIG. 2 during movement of the moving part of the hand-held part into a working position;

[0061] FIG. 5 shows a diagram corresponding to FIG. 4 with an opened return valve and actuated pressure-increasing piston;

[0062] FIG. 6 shows an enlargement of the region VI in FIG. 5;

[0063] FIG. 7 shows the underview towards the hand-held device according to arrow VII in FIG. 1.

[0064] Shown and described initially with reference to FIG. 1 is a hydraulically operated hand-held device 1 in the form a pressing device with an electric motor 2, a hydraulic pump not shown in detail, a hydraulic medium storage chamber 3 and a moving part 4 configured as a hydraulic piston.

[0065] The moving part 4 is movable relative to a fixed part 5 formed by the device housing or for example the cylinder in which the hydraulic cylinder moves. The moving part 4 is now for example the tool holder shown in FIG. 1. It can for example also comprise the hydraulic piston (see possibly FIG. 2).

[0066] In particular, the components hydraulic medium storage chamber 3, return valve 8, adjusting device 27 and optionally others are accommodated in a device body K not shown in further detail here.

[0067] The hydraulic chamber 6 comprises the chamber into which the hydraulic medium is pumped. This begins on the pressure side of the hydraulic pump. As shown for example in FIG. 2, the hydraulic chamber 6 has a return line 7 via which the hydraulic medium can flow back via a return valve 8 into the hydraulic medium storage chamber 3.

[0068] As can be seen in particular from FIGS. 4 and 5, the hydraulic chamber 6 changes with the working state of the hand-held device 1. In the diagram according to FIG. 4, the moving part 4 is in a changed position compared with FIG. 2. After opening the return valve 8 (FIG. 5), the hydraulic piston or the moving part 4 moves back in the direction of its rest position according to FIG. 2. The space upstream of the hydraulic piston in this respect is included in the hydraulic chamber 6 but at the same time when the return valve is open, the passage through the valve seat and the space directly upstream of the return valve 8.

[0069] The electric motor 2 for operating the hydraulic pump and therefore for moving the moving part 4 in the direction of the working position is activated via a switch 9 preferably configured as a manually actuatable button. The power supply as well as further preferably a switch/control electronics is accomplished via a device-side rechargeable battery not shown or an electrical line.

[0070] In the valve closure position the return valve 8 is pressed into the valve seat by means of a pressure spring 10. The valve seat preferably consists in detail of a screw-in part 12 which is screwed into the housing of the hand-held device 1 via a thread 11.

[0071] A flow hole 13 is provided in the valve seat, optionally in the screw-in part 12. This is in fluidic communication with the return line 7.

[0072] As a result of the narrow cross-section of the flow hole 13 in the valve seat in cooperation with the pretension applied by the pressure spring 10, the return valve 8 only opens when a specific triggering pressure is exceeded. This is the initially mentioned predefined working pressure. This triggering pressure can for example be 600 or 700 bar.

[0073] After the return valve 8 has opened, the pressure of the hydraulic medium is no longer applied to the area corresponding to the cross-sectional area of the flow hole 13, a partial piston surface, given for example by a valve needle 14, but to the entire area (subsurface 17) facing the hydraulic chamber of the return valve piston 15 of the return valve 8 having the valve needle 14. The open return valve 8 is therefore already held in the open position by a very low pressure in the return line 7, for example a pressure of 2 to 5 bar.

[0074] The valve needle 14 need not be formed in an ideally tapering manner. Preferably it is formed to be conical in any case.

[0075] This pressure is preferably produced during the return of the moving part 4 by a spring 16 which acts on the moving part 4 and which loads the moving part 4 into the end position.

[0076] In the drain flow direction after the flow hole 13 the pressure is again significantly lower. For example, the pressure in particular at the beginning of the return of the moving part is only or less than the pressure upstream of the flow hole 13 or the valve seat, in practice for example approximately half. This pressure difference however substantially equalizes thereafter and is usually only comparatively low soon after the beginning of the return of the moving part.

[0077] After opening of the return valve 8, the space 26 adjoining the flow hole 13 as far as the subsurface 17 of the return valve piston 15 is included in the hydraulic chamber. The hydraulic medium then flows via a drain opening 18 into the storage chamber 3. The chamber 26 is also designated hereinbefore and hereinafter as valve chamber.

[0078] An axial hole 19 passing through the subsurface 17 and preferably rebound-protected, allows a backflow of hydraulic medium from the hydraulic medium storage chamber into the valve chamber 26 in the closure state of the return valve 8 according to FIGS. 2 and 3 in particular to facilitate a return of the pressure-increasing piston 22 (see on this matter further below).

[0079] Without any further measure, in particular without any external intervention, for example by the user, the hydraulic or triggering pressure which raises the valve needle 14 from the valve seat corresponds to the said predefined working pressure at the moving part 4.

[0080] However, a possibility has been provided for moving the return valve 8 into its open position without the hydraulic pressure required to raise the return valve 8 being present at the moving part 4. Accordingly, work, for example, pressings with the hand-held device 1 is possible which requires lower working pressures at the moving part 4 compared with the triggering pressure for the return valve 8.

[0081] For this purpose, preferably a further line 20 filled with hydraulic fluid is provided which is assigned to the hydraulic chamber adjoining the flow hole 13 in the downflow direction. This line 20 is continued in a hydraulic medium cylinder 21 in which the pressure-increasing piston 22 already mentioned is preferably linearly displaceable. The line 20 could also be configured to be shorter as shown or omitted.

[0082] By means of an electrically controllable adjusting magnet 23, a linear movement of the pressure-increasing piston 22 in the hydraulic medium cylinder 21 or in the line 20 can be achieved. The movement of the pressure-increasing piston 22 brought about by activation of the adjusting magnet 23 is preferably accomplished contrary to the force of a return spring 24 acting on the pressure-increasing piston 22.

[0083] Via the holes provided for example in the screw-in part 12, preferably aligned in the direction of displacement of the return valve 8, the line 20 hydraulically forms a part of the chamber 26.

[0084] In the installed state the screw-in part 12 does not abut directly against the facing housing wall so that hydraulic medium moved by the pressure-increasing piston 22 can readily flow from the line 20 via the holes 25 into the part of the chamber 26 located downstream of the valve seat in the drain direction of the hydraulic medium.

[0085] The hand-held device 1 preferably has an adjusting device 27 by means of which the maximum working pressure present at the moving part 4 can be preset by the user. In the exemplary embodiment shown here, a multiplicity of buttons 28 are provided for this purpose, for which buttons predefined pressure values are stored. By means of the adjusting device, the previously described selected working pressure modified compared with the predefined working pressure (or even agreeing with this in individual cases) can be set accordingly. Reference is made at this point to the further, optionally alternative possibilities of the initially mentioned radio connection etc.

[0086] Thus, for example, a working pressure of 200 bar or 300 bar resulting in a triggering of the return valve can be preselected.

[0087] An evaluation/control electronics evaluates pressure measured values of a pressure sensor 29 in the course of the movement of the moving part 4 in the direction of the working position and compares this with the desired pressure value predefined via a button 28.

[0088] On reaching the desired pressure value, a corresponding signal is generated which results in an activation of the adjusting magnet 23.

[0089] The pressure-increasing piston 22 moves as a result of the activation of the adjusting magnet 23 against the force of the preferably provided return spring 24 abruptly into the advance position according to the diagrams in FIGS. 5 and 6. As a result the pressure-increasing piston 22 moves into a close, almost circumferentially sealed cooperation with the hydraulic medium cylinder 21 of the line 20. Hydraulic medium located upstream of the pressure-increasing piston 22 is displaced in a direction of travel of the pressure-increasing piston 22 in the direction of the return valve 8 and thus in the depicted exemplary embodiment into the space downstream of the flow hole 13. It is therefore displaced relative to the closed state of the return valve 8 into the space formed by the subsurface 17 and the associated side of the screw-in part 12 as well as a part of the cylinder in which the return valve 8 is accommodated. This is the chamber 26 which has already been discussed, the valve chamber. As a result, this valve chamber is acted upon in the sense of a reduction in size. This results in a short-term pressure increase in the chamber 26 to act on the subsurface 17 of the return valve 8. As a result of the action of the substantially increased diameter area of the subsurface 17 compared with the cross-sectional area of the flow hole 13 in the valve seat, the return valve 8 can already be raised due to the build-up of a pressure of a few bar, for example 2 to 5 bar. This pressure is (initially) only achieved by the piston-like displacement of the pressure-increasing piston 22.

[0090] The valve needle 14 is thereafter raised from the valve seat so that the hydraulic medium can return from the hydraulic chamber 6 back into the hydraulic medium storage chamber 3, wherein the return valve 8 is in this case held in the raised position until the moving part 4 reaches the end position according to FIG. 2 and thus the holding-open pressure for the return valve 8 is fallen below.

[0091] The pressure increase at the return valve 8 due to the pressure-increasing piston 22 acts in an initial manner. With raising of the return valve 8 and accompanying connection of the chamber 26 to the drain opening 18 with simultaneous opening of the flow hole 13, the pressure prevailing due to the return of the moving part 4 acts on the return valve 8.

[0092] The electrical action of the adjusting magnet 23 can initially take place in a pulsed manner so that after the complete initial stroke of the pressure-increasing piston 22, this is located almost immediately in the advanced position according to FIG. 6. With a regular sequence of a working cycle when in particular therefore no premature ending of the return of the moving part is desired, the pressure-increasing piston 22 preferably remains in this position as a result of action of the adjusting magnet 23 also occurring for this length of time.

[0093] As a result of an, as it were, premature cancellation of the action of the adjusting magnet 23 which has taken place before the complete return movement of the moving part, the pressure-increasing piston 22 can accordingly move back prematurely into its initial position. The associated increase in the valve chamber 26 can ensure a pressure drop such that a desired closure of the return valve 8 is achieved by this means.

[0094] With a return movement of the pressure-increasing piston 22, preferably at the same time a flow path from the hydraulic medium storage chamber 3 into the valve chamber 26 opens in order to supply the valve chamber 26 with the required hydraulic medium which enables the said backward movement of the pressure-increasing piston 22. As soon as the return valve 8 is closed again, no more hydraulic medium can flow into the chamber 26 via the valve seat. This flow path can be given by a check valve arranged in the valve piston and/or a connecting path from the hydraulic medium storage chamber 3 to the line 20. Also with a return movement of the pressure-increasing piston 22 a (further) drain path for hydraulic medium into the hydraulic medium storage chamber 3 initially via a line section 31 which is released by the back-moving pressure-increasing piston 22, can be [provided]. Further however additionally or alternatively via a receptacle 32 for a piston shaft 33 of the pressure-increasing piston 22. Via this and the preferably adjoining expanded chamber 33 in which an actuating piston 34 of the pressure-increasing piston 22 is located, hydraulic medium can drain directly into the hydraulic medium storage chamber 3.

[0095] In the actuated state, see FIG. 5 and in particular FIG. 6, it is also important that a front, here conically shaped surface of the actuating piston 34 abuts directly against the associated wall. On the other hand, the actuating piston 34 does not completely fill the expanded space 33 in the rearward direction hereto. As a result of a flattening or the like on one of its sides, on the contrary a free space 35 remains in the expanded space 33 in the advanced state during actuation according to FIG. 6.

[0096] The forwards movement of the moving part 4 into the working position is preferably only retained for as long as the user actuates the switch 9. In one embodiment with release of the switch 9 (even before completion of a working process) a signal is generated which results in a triggering of the adjusting magnet 23 and therefore via the pressure-increasing piston 22 results in a pressure increase in the chamber 26. Accordingly, with release of the switch 9 the return valve 8 is displaced into the open position which results in an automatic return of the moving part 4 into the end position.

[0097] The pressure-increasing piston 22 can be arranged transversely directed to the return valve 8. The longitudinal axes of pressure-increasing piston 22 and return valve 8 intersect outside the respective extension regions. This assists a desired compact design.

[0098] In addition, it can be provided as shown in the exemplary embodiment that the adjusting magnet 23 or the relevant structural section is flushed by hydraulic medium by projecting into the hydraulic medium storage chamber 3.

[0099] The preceding explanations are used to explain the inventions covered total by the application which in each case independently further develop the prior art at least by the following feature combinations, namely:

[0100] A method characterized in that the hydraulic pressure acting on the return valve 8 is increased to trigger a movement of the moving part 4 into the end position independently of reaching the predefined working pressure.

[0101] A method characterized in that the return valve 8 is opened automatically at a modified working pressure compared with the predefined working pressure.

[0102] A method characterized in that the modified working pressure can be set.

[0103] A method characterized in that the increase in the hydraulic pressure is accomplished for a short time.

[0104] A method characterized in that the increase in the hydraulic pressure is accomplished by supplying hydraulic medium into a given chamber 26 downstream of the valve seat with a view to a drain direction of the hydraulic medium.

[0105] A method characterized in that the increase in the hydraulic pressure is accomplished by a movement of a pressure-increasing piston 22.

[0106] A method characterized in that the pressure-increasing piston 22 is moved into a hydraulic medium cylinder 21.

[0107] A method characterized in that the hydraulic medium cylinder 21 is continuously connected to a return line 7 of the hydraulic medium.

[0108] A method characterized in that the hydraulic medium cylinder 21 is only hydraulically in communication with the return line 7 of the hydraulic medium when the return valve is open.

[0109] A method characterized in that the pressure-increasing piston 22 is moved via a separate drive from a drive of the hydraulic pump.

[0110] A method characterized in that the pressure-increasing piston 22 is moved by means of an adjusting magnet 23.

[0111] A method characterized in that a return of the moving part 4 is accomplished depending on a pressure value measured by the pressure sensor 29 by subsequent automatic opening of the return valve 8 and that the working pressure at which the opening of the return valve 8 is triggered is adjustable.

[0112] A method characterized in that when the actuation of a switch or button by the user is cancelled, an opening of the return valve and a return of the moving part 4 is triggered at the same time.

[0113] A method characterized in that the return of the moving part 4 is only triggered when a first workpiece contact has been determined previously on the device side.

[0114] A hand-held device characterized in that the hydraulic pressure acting on the return valve 8 can be increased independently of reaching the predefined working pressure to a pressure value which brings about an opening of the return valve 8.

[0115] A hand-held device, characterized in that a movable pressure-increasing piston 22 is provided to increase the pressure.

[0116] A hand-held device characterized in that the pressure-increasing piston 22 is movable in a hydraulic cylinder 21 which is continuously hydraulically in communication with a return line 7 of the hydraulic medium.

[0117] A hand-held device characterized in that the pressure-increasing piston 22 is movable by means of a drive separate from a drive of the hydraulic pump.

[0118] A hand-held device characterized in that the pressure-increasing piston 22 is movable by means of an adjusting magnet 23.

[0119] A hand-held device characterized in that the hydraulic volume which can be used to increase the pressure value on the return valve 8 is in communication with the hydraulic storage chamber 3 via a return valve 30.

[0120] A hand-held device characterized in that a return of the moving part 4 can be accomplished depending on a pressure value measured by the pressure sensor 29 by a triggerable opening of the return valve 8 and that the working pressure at which the opening of the return valve 8 can be selected to differ from the predefined working pressure.

[0121] A hand-held device characterized in that an adjusting device 27 is provided for different selected working pressures.

[0122] A hand-held device characterized in that a return of the moving part 4 can be triggered by cancelling the actuation.

REFERENCE LIST

[0123] 1 Hand-held device [0124] 2 Electric motor [0125] 3 Hydraulic medium storage chamber [0126] 4 Moving part [0127] 5 Fixed part [0128] 6 Hydraulic chamber [0129] 7 Return line [0130] 8 Return valve [0131] 9 Switch [0132] 10 Pressure spring [0133] 11 Thread [0134] 12 Screw-in part [0135] 13 Through hole [0136] 14 Valve needle [0137] 15 Return valve piston [0138] 16 Spring [0139] 17 Subsurface [0140] 18 Drain opening [0141] 19 Axial bore [0142] 20 Line [0143] 21 Hydraulic medium cylinder [0144] 22 Pressure-increasing piston [0145] 23 Adjusting magnet [0146] 24 Return spring [0147] 25 Hole [0148] 26 Chamber [0149] 27 Adjusting device [0150] 28 Button [0151] 29 Pressure sensor [0152] 30 Check valve [0153] 31 Line section [0154] 32 Receptacle [0155] 33 Chamber [0156] 34 Actuating piston [0157] 35 Free space [0158] K Device body