EP0828942B1 - Hydropneumatic machine tool - Google Patents

Abstract

A machine tool is proposed which operates with a hydropneumatic pressure intensifier whose step piston (1) is braked hydraulically in particular towards the end of its stroke by forcing hydraulic fluid from a braking cavity (35) formed during the stroke via a choke point.

Description

The invention is based on a hydropneumatic Machine tool according to the genus of the main claim. In a known machine tool generic type (DE-P 43 01 983) is the working stroke of the working piston by belching the rapid traverse serving the largest diameter, namely the Drive piston, to the bottom of the corresponding pneumatic work space braked, being on the Drive piston surface there is a damping disc, which, however, causes only a slight damping.

Such generic machine tools are in themselves fast working and energy saving pneumatic systems, in which a hydraulic system is integrated, through which after the desired advance stroke in the working direction Power stroke with a very high actuating force can be achieved. Although after outside of the machine tool housing only pneumatic connections are available, the Pressure translation using the hydraulics. Hereby hydraulic chambers pass next to the piston stroke direction Pneumatic rooms, with the not inconsiderable problem of Sealing from one to the other. In the Air entering hydraulic fluid leads to undesirable Compressibility of the oil; from the hydraulic part leaking oil can lead to malfunctions.

One with such hydropneumatic pressure ratio working machine tool problem remains the damping of the working stroke or sometimes the Return stroke. Especially if you have a corresponding Tool made for example a sheet metal connection and should be supported when the stepped piston is idling by the weight of the tool with full force into one pops its end positions, this can not only lead to one cause significant noise, but also cause corresponding damage. Although this one old general problem of such machine tools is was none other than the above-mentioned elastic disc in particular also on the weight or the mass of the Tool adjustable damping found.

The machine tool according to the invention with the has characteristic features of the main claim in contrast the advantage that depending on Throttle cross section a more or less strong Damping especially towards the end of the working stroke can be reached, this cross section at the throttle point can be adapted to the masses. For this damping can the hydraulic fluid can be used with the other hydropneumatic pressure intensifier works. The seals of high quality anyway between pneumatic room and hydraulic room also serve to seal the annulus, so that an additional elaborate seal is not required. Anyways the invention in a very simple manner and very effective and overcoming the bias of the Realize the professional world on such machine tools. It is known that the end position of the working cylinder Damping the working piston hydraulically or pneumatically, only it is not a step piston with the problems mentioned above.

According to an advantageous embodiment of the invention the stepped piston displaces at least towards the end of the Return strokes and to brake its return stroke movement liquid from the annulus through a restriction. On this way both the forward and the reverse run of the step piston and thus the lower dead center area and the top dead center area of the tool at Damped stroke movement, the damping of the Working strokes arranged on the stepped piston additional piston collar with its during the working stroke used ring surface facing away from the ring surface Return stroke damping causes.

According to a further advantageous embodiment of the Invention has the annulus on at least one of its End sections one the diameter of the piston collar corresponding taper into which the piston collar immersed towards the end of the stroke, the one in this being Volume of fluid enclosed by the brake chamber Throttle point is displaced. This will only towards the end of the stroke of the working stroke or return stroke Lifting movement braked or damped. Instead, can the entire lifting movement can be braked by the piston collar to the cylinder wall more or less seals or those located on both sides of the piston collar Annuli connected to each other via a throttle channel are.

According to a further advantageous embodiment of the Invention is the annulus with the work space during of the working stroke and / or return stroke. To this Depending on the control, the hydraulic fluid can get unrestricted from the annulus to the work area, if you don't want to slow down. This also affects the refilling of hydraulic oil about the always provided extra Refill devices for the hydraulic Damping off. However, the annulus can completely be separate from the work area and at a different location of the stepped piston, for example in the area the piston rod.

According to a further advantageous embodiment of the Invention serves as a throttle point between the piston collar and given annulus wall play. In case of a Taper in the end sections of the annulus acts of course, the damping only in these areas.

According to a further advantageous embodiment of the Invention branches off from the brake chamber, a relief channel in which is a control for controlling the Liquid passage is present. This Relief channel can according to the invention again in the Annulus open. So the relief channel can also from one brake chamber to the other, the Brake rooms are activated alternately and in the Relief channel can also be arranged two controls can, one for one and the other for the other Brake chamber, which are then alternately effective.

According to a further advantageous embodiment of the Invention is the brake space with the storage space connecting bypass duct with one to the storage room blocking check valve available. Such a bypass bypasses the point at which the plunger working space and Storage space separates from each other to thereby during the Rapid strokes to quickly fill up the work area. In the invention, this is in at the beginning of the rapid stroke A quick refill of the working stroke Workspace achieved through the braking space.

According to a further advantageous embodiment of the Invention is the annulus with the work space connecting bypass duct with one to the work area blocking check valve available. Advantageously this bypass channel runs in the working piston. About the Check valve becomes a pressure equalization when driving off of the stepped piston reached from its end position, i.e. before Start of the return stroke.

According to a further advantageous embodiment of the Invention is the annulus with the work space connecting short-circuit channel arranged in the working piston, its mouth on the surface of the piston collar is present and which towards the end of the working stroke at least in part due to the taper in the annulus is closed. This short-circuit channel also serves as Overflow hole for volume compensation when starting off the stepped piston from its starting position, i.e. closed Start of the work stroke.

After another, also claimed for itself Embodiment of the invention is the storage space in one Storage cylinder arranged and over a storage piston limited, which to generate a memory pressure the side facing away from the storage space is under low pressure (pneumatic or spring), the Central axis of the storage cylinder parallel but at a distance is arranged to that of the working piston and wherein Storage space and work space within one common machine housing are housed. It is although known in one with a hydropneumatic Pressure intensifier working welding machine Hydraulic accumulator outside the machine housing to arrange and this with a hydraulic line Connect the machine's working area (US-PS 38 75 365). However, such a device is practically only for stationary built-in machine tools usable.

According to an advantageous embodiment of the Invention is used to generate a low pressure Coil spring. This has the advantage that Hydraulic oil always under one for venting the Hydraulic range sufficient low pressure is available. At the use of pneumatics for the piston loading of the Memory will normally become during the return stroke switched off, with the disadvantage that then none Bleed the hydraulic area can.

After a further design of the Invention is at the storage piston outside of the Storage cylinder projecting control rod arranged with a longitudinal channel leading to the storage space, the End facing away from the storage space in an outward direction closed control room that is visible from the outside flows. This allows the actual oil level to be changed at any time be visually ascertained in all Work steps, namely for rapid stroke, working stroke and Return stroke.

After a further design of the Invention is the control room in one at the end of the Control rod attached and transparent control bush arranged. This control socket can be made of glass or Plastic. In any case, it is for the operator of the Machine tool therefore very simple, an oil shortage ascertain.

According to a further advantageous embodiment of the Invention is the control room over a Venting device can be vented to the outside. This Venting device can advantageously be a bore be the continuation of the longitudinal channel through the Control room is conceivable.

According to a further advantageous embodiment of the Invention is that hydraulic connection between Storage space and work space as one in the Machine housing arranged transverse bore formed, which are accessible from outside the machine housing and can be used for oil refilling. Depending on the location of the Machine tool can also use this hole for ventilation serve.

According to a further advantageous embodiment of the Invention is the plunger coaxial with that Working piston arranged and via a pneumatic piston can be operated against the force of a return spring. Especially when the storage space is not around Plunger but at a distance and parallel to it is arranged, the pneumatic piston of the Working cylinder receiving plunger shortened be, whereby the total length of the Machine tool can be shortened.

According to a further embodiment of the Invention, the pressure generator has a plunger coaxially arranged storage space, the common longitudinal axis parallel to that of the stepped piston is arranged with a the pressure generator with the Working space connecting pressure channel, whereby after Termination of the working stroke and the like Afterflow of liquid from the storage space into the Working space the pressure channel through the plunger is blocked, after which the plunger continues to lift A high pressure can be generated in the work area. In principle it is such an arrangement is known (DE-P 43 01 983).

Further advantages and advantageous configurations of the Invention are the following description of the Drawing and the claims can be removed.

Fig. 1

das erste Ausführungsbeispiel im Längsschnitt;

Fig. 2

eine Variante des ersten Ausführungsbeispiels als Ausschnitt;

Fig. 3

eine weitere Variante des ersten Ausführungsbeispiels ebenfalls als Ausschnitt;

Fig. 4

das zweite Ausführungsbeispiel und

Fig. 5

das dritte Ausführungsbeispiel als Ausschnitt.

Three embodiments of the subject matter of the invention are shown with variants in each case in longitudinal section in the drawing and are described in more detail below. Show it:

Fig. 1

the first embodiment in longitudinal section;

Fig. 2

a variant of the first embodiment as a section;

Fig. 3

another variant of the first embodiment also as a section;

Fig. 4

the second embodiment and

Fig. 5

the third embodiment as a section.

All three exemplary embodiments work as stroke-controlled Machine tools with one hydropneumatic each Pressure translator. With such a pressure translator for a rapid traverse, namely moving the tool up compressed air is used on the workpiece, whereas for the actual operation through one also Compressed air driven pistons a high pressure hydraulic is generated by means of which the tool is actuated.

For the sake of simplicity, the following are Description for the corresponding parts the same two-digit reference numbers are used, these being the same Reference numbers for the first and second variant of the first embodiment in Figs. 2 and 3 each around Increase number 100 and the second and third Embodiment around 200 to 300.

In the first embodiment shown in FIG a step piston 1 available, the individual steps through a working piston 2, a driving piston 3 and one Piston rod 4 are formed. The working piston 2 works in a working cylinder 5, which is part of the Machine housing 6 and to which a cylinder tube 7th connects in which the drive piston 3 works and on which on the side facing away from the working cylinder 5 a cylinder head 8 is arranged in the central Bore the piston rod 4 is mounted. The drive piston 3 is in a known manner on both sides by compressed air acted upon, whereby a rapid traverse of this stepped piston in is effected in both stroke directions.

Axial to the stepped piston 1 is in the upper part of the Machine tool a plunger 9 shown by a pneumatic piston 11 is driven and in the Drawing each in half in two different ways Diameters are shown, with each diameter naturally causes a different oil displacement per lifting unit. The pneumatic piston 11 works in a cylinder tube 12, which is placed on the machine housing 6 and is closed by a cylinder head 13. About this Cylinder head 13 is also the compressed air for actuating the Pneumatic piston 11 supplied, the adjustment takes place against a restoring force, for example can be controlled compressed air or a coil spring can be. The plunger 9 dives with its free end in a room 14 with one below one Ring seal 15 located work space 16 is connected, so that the plunger 9 during its stroke movement and penetrate the ring seal 15, the space 14 before Room 16 separates and according to its cross-sectional area a corresponding hydraulic high pressure in Workspace 16 generated.

The space 14 is a extending in the housing 6 Cross bore 17 connected to a storage space 18, the arranged essentially in a pneumatic cylinder 19 and is limited by a storage piston 21 upwards is. The storage piston 21 is in the direction of the storage space 18 loaded by a coil spring 22, which is on the Accumulator piston 21 facing away from a cylinder head 23 of the pneumatic cylinder 19 supports. On the storage piston is an outside of the cylinder head 23 and this penetrating control rod 24 arranged in which one the whole control rod in the longitudinal direction penetrating control hole 25 is present, which in a control room 26 opens. The control room 26 is in front all in one made of transparent material such as plastic or glass existing screw nipple 27 arranged to thereby being able to recognize from the outside whether there is air in Hydraulic oil has reached. Via a vent hole 28 can be vented if necessary. To protect the The viewer is coaxial around the control rod 24 transparent protective tube 29 on the cylinder head 23 stuck.

On the outer surface of the working piston 2 is a Piston collar 31 arranged and it is in the working cylinder 5th an annular groove 32 is present, which towards the working piston 2 forms an annular space 33 and at both ends Tapered 34 has the diameter of the Piston collar 31 corresponds to how it is on an enlarged scale is shown in Fig. 2. As soon as the piston collar 31 against End of its forward stroke or its return stroke into this Immerses taper 34, he limits one here to 35 designated brake chamber. That in this brake room trapped liquid volume is about a Throttle point displaced, as is the case with FIG. 2 is explained. In the illustrated in Fig. 1 The embodiment is the plunger 9 with the same axis arranged the stepped piston 1 and it is the Accumulator piston 21 parallel to the axes of the Storage piston 9 and step piston 1 arranged, but with Distance to the same. According to the invention between the Working space 16 and the storage space 17, 18 a bypass 40, which is only shown in broken lines, can be arranged in through a check valve only a flow is possible in the direction of the work space 16, however the flow from the working space 16 to the storage space 17, 18th Is blocked.

In the variant of this first shown in FIG. 2 The exemplary embodiment is the plunger 109 having pressure generators parallel to the axis of the Step piston 101 arranged, the storage space 118 is arranged coaxially to the plunger 109. Thereby creates a relatively large work space 116, namely between the ring seal 115, in which the Plunger 109 for generating the working pressure dips and the upper end of the working piston 102. The "harmful space" of the Workspace enlarged, but with the advantage that the Space-saving pressure generator next to the working cylinder is arranged.

As shown on an enlarged scale in Fig. 2, the Working piston 102 on a head part 36, which by Screws 37 with the rest of the working piston 102 is connected and in which bypass channels 38 and 39 is arranged, the respective brake chamber 35 with the Connect workspace 116 (workspace 16 in FIG. 1). In these bypass channels 38, 39 are in the area of Mouth to the working space 116 check valves 41 arranged that only a flow in the direction Allow brake chamber 35. As soon as the piston collar 31 in the taper 34 of the annular groove 32 dips and thus the respective brake chamber 35 can be limited from this Brake chamber 35 via these bypass channels 38, 39 none Drain hydraulic fluid more into the work area. In In the drawing, the working piston 102 takes its upper one Starting position, i.e. the position before the start of the rapid stroke. As soon as the working piston 102 has its drive piston 3 pneumatically driven downwards via its rapid traverse can, via the bypass channel 38 or there arranged check valve 41 hydraulic oil from the Follow workspace 116 into the brake chamber so that insofar as the drive is not obstructed. As soon as then the piston collar 31 has emerged from the taper 34, creates a hydraulic connection between the Annulus 33 un the work space 116, so that the Piston collar 31 is freely movable. Once the end of the Rapid stroke is reached, then the driven driven Plunger 109 through the ring seal 115 in the Working space 116 and actuates the working piston 102 a corresponding hydraulic high pressure. The Effect of the hydropneumatic pressure intensifier results by the cross-sectional difference of the plunger 109 with a relatively small cross section and Working piston 102 with a relatively large cross section. As soon as the piston collar 31 dips into the lower taper 34, there is a Brake chamber 35 formed. Although the bypass channel 39 from branches off this brake chamber 35 is in this stroke direction through the check valve 41 the connection to Work room 116 locked. Only when the return stroke of the working piston 102 begins, can Check valve 41 and the bypass channel 39 hydraulic oil in flow this brake chamber, so that over the To prevent drive piston 3 caused rapid return stroke. First then when the piston collar 31 back into the upper Taper 34 emerges, there is again a brake chamber 35 educated.

As shown in FIG. 1 and in the variant according to FIG. 2, branches off from the brake chambers 35 in each case Relief channel 42 and 43 from the annular space 33 flow out. There is one in each of these relief channels Throttle valve 44 arranged. So as soon as in the Brake spaces 35 due to the piston collar 31 appropriate pressure arises, the imprisoned Hydraulic fluid at the upper end stroke over the Relief channel 32 and the lower end stroke over the Relief channel 43 and in each case via the throttle valve 44 displaced back into the annular space 33. Based on these Throttling effect arises from the throttle cross section appropriate damping of the remaining stroke of the working piston 102. The throttle valve 44 is adjustable in cross section, see above that this braking or damping effect each Tool or its function is customizable. A additional control effect can be achieved by the annular space 33 connecting to the work space 116 (16) Short-circuit channel 45 can be achieved, the mouth of the Annular space 33 on the outer surface of the piston collar 31 is ordered and only after a certain one has traveled Plunging stroke of this piston collar 31 into the taper 34 is locked in. Since this short circuit bore 45th is independent of the brake chamber 35, it has no influence on braking, but has the advantage that when Moving the working piston 102 out of the illustrated top dead center position at this rapid traverse a quick Volume compensation between the annular space 33 and the work space 116 can take place.

3 is a further variant of this first Embodiment shown, which largely from that Fig. 2 corresponds and only has the difference that between the piston collar 31 and the taper 34 There is an annular gap through which the desired however, a changeable throttle effect arises in which that stroke movement from the brake chamber 35 Hydraulic fluid is displaced into the annular space 33. For some uses of the machine tool according to the invention such a non-adjustable one is enough less effective damping of the working piston 102. Otherwise, the variant shown here works like that from Fig. 2, especially as far as the short-circuit channel 45 is concerned.

In the second embodiment shown in FIG. 4 is the braking device according to the invention in the area the piston rod 104 relocated. The remaining parts like that Working piston 2, the plunger 9 and the drive piston 3 essentially correspond to the variant of the first Embodiment, which is shown in Fig. 1. this applies also for their function. The storage space 218, however, is in its central axis here transverse to the axis of the stepped piston 201 arranged, however, on the function of this second Embodiment has no influence. The piston rod 104 here has a piston collar 46, which in one Annulus 47 of the cylinder tube 107 reciprocally is and in the respective stroke end positions by tapering 48 of the annular space 47 brake spaces 49 limited. This Brake chambers 49 each have relief channels 51 which can be connected, for example, in which however, a throttle body is arranged. The advantage of this second embodiment is mainly that the area of the working piston with its changing hydraulic high pressures is not affected and that in a kind of modular system such an insulation device can be mounted on a machine tool, only the cylinder tube 107 or the piston rod 104 is designed differently accordingly.

In the third embodiment shown in FIG. 5 acts the braking or damping device on the total stroke of the stepped piston 301. The working piston 302 is to his working cylinder 305 through ring seals 52 radially sealed, so that the resulting Annulus 53 acts as a brake space as soon as that in this Annulus 53 existing hydraulic fluid via a Control channel 54 and a corresponding device is throttled. The machine tool works otherwise as described for the first embodiment.

All of the description, claims and drawing removable features can be used both individually and in any combination essential to the invention his.

List of reference numbers

1, 101, 201, 301

Stepped piston

2, 202, 302

Piston

3rd

Drive piston

4, 104

Piston rod

5, 305

Working cylinder

6, 106

Machine housing

7, 107

Cylinder barrel

8th

Cylinder head

9, 109

Plunger

10th 11

Pneumatic piston

12th

Cylinder barrel

13

Cylinder head

14

room

15, 115

Ring seal

16, 116

working space

17th

Cross hole

18, 118, 218

Storage space

19th

Pneumatic cylinders

20th 21

Storage space

22

Coil spring

23

Cylinder head

24th

Control rod

25th

Control hole

26

Control room

27

Screw nipple

28

Vent hole

29

Protective tube

30th 31

Piston collar

32

Ring groove

33

Annulus

34

rejuvenation

35

Brake chamber

36

Headboard

37

Screws

38

Bypass channels

39

Bypass channels

40

Bypass channels

41

check valve

42

Relief channel

43

Relief channel

44

Throttle valve

45

Short-circuit channel

46

Piston collar

47

Annulus

48

Rejuvenation

49

Brake chamber

50 51

Relief channel

52

Ring seals

53

Annulus

54

Control channel

Claims (19)

1. A hydro-pneumatic machine tool

   with an axially displaceable, at least three-stage differential piston (1, 101, 201, 301) for its working or return stroke, featuring a hydraulically impinged stage serving as the working piston (2, 102, 302), and at least on the one hand, a pneumatically impinged stage with the greatest diameter serving as a driving piston (3) for rapid traverse and a stage serving as a piston rod (4, 204) located on the back side of the working piston;

   with a machine casing (6, 106) featuring a step hole corresponding to the differential piston;

   with a hydraulic working chamber (16, 116) and at least a pneumatic working chamber between the differential piston and the radial seals on the steps that separate the step hole;

   with a pressure generator especially working with a plunger piston (9, 109) that generates a high hydraulic pressure inside the working chamber (16, 116) during a working phase;

   with an accumulator space (18, 118, 218) hydraulically connectable with the working chamber (16, 116), but separated from the latter during the working phase,

   characterised in that

   an additional piston collar (31, 46) is located on the working piston (2, 102) or on the piston rod (204);

   this piston collar is movable in a correspondingly designed, hydraulic annular chamber within the step hole,

   the piston collar (31, 46) displaces the fluid from the annular chamber (33, 47, 53) through a throttling section (34, 44) to retard piston motion at least at the end of the working stroke.
2. Machine tool according to Claim 1, characterised in that the differential piston (1, 101, 201, 301) also displaces the fluid from the annular chamber (33, 47, 53) through a throttling section (34, 44) at least towards the end of the return stroke, to retard the return stroke motion.
3. Machine tool according to Claim 1, or 2, characterised in that the annular chamber (33, 47, 53) features a throttling section (34, 48) corresponding to the diameter of the piston collar (31, 46) on at least one of its end sections in which the piston collar (31) dips at the end of a stroke and displaces the fluid trapped inside this braking chamber through the throttling section (31, 34, 44).
4. Machine tool according to one of the preceding claims, characterised in that the annular chamber (33) can be connected with the working chamber (16, 116) during the working stroke and/or return stroke.
5. Machine tool according to Claim 3 or 4, characterised in that the clearance created between the piston collar (31) and the annular chamber wall (32, 34) serves as a throttling section.
6. Machine tool according to one of Claims 3 up to 5, characterised in that a discharge channel ( 42, 43, 51, 54) branches off from the fluid braking volume (35, 49) (the enclosed volume) in which a control element (44) is provided for controlling fluid passage.
7. Machine tool according to Claim 6, characterised in that the discharge channel leads into the annular chamber.
8. Machine tool according to Claims 3 up to 7, characterised in that a bypass channel (40) connecting the braking chamber (35) with the accumulator space (17, 18) is provided with a check valve that closes towards the accumulator space.
9. Machine tool according to Claims 3 up to 8, characterised in that a bypass channel (38, 39) connecting the annular chamber (33) with the working chamber (16, 116) is provided with a check valve (41) that closes towards the working chamber.
10. Machine tool according to one of Claims 3 up to 9, characterised in that a short-circuit channel (45) connecting the annular chamber (33) with the working chamber (16, 116) is located inside the working piston with the orifice located on the piston collar (31) and can be closed at least partially through the throttling section (34) inside the annular chamber (33) towards the end of the working stroke.
11. Machine tool according to one of the preceding claims, characterised in that the accumulator space (18) is located inside a accumulator cylinder (19) and is confined by means of a accumulator piston (21) which is subjected to low pressure (pneumatic or spring) for generating storage pressure on the back side of the accumulator space (18); and that the middle axis of the accumulator cylinder (19) is located parallel but at a distance to that of the working piston (2) and that the accumulator space (18) and the working chamber (16) are accommodated within a common machine casing (6). (Fig. 1).
12. Machine tool according to Claim 11, characterised in that a spiral spring (22) is provided for generating low pressure.
13. Machine tool according to Claim 11 or 12, characterised in that a control rod (24) that projects outwards of the accumulator cylinder (19) is located on the accumulator piston (21) with a longitudinal channel (control hole 25) leading into the accumulator space (18) whose back end -viewed from the accumulator space (18) - leads into a control volume (26) that although closed, remains visible from outside.
14. Machine tool according to Claim 13, characterised in that the control volume (26) is located in a transparent (glass or plastic) control sleeve (screwed nipple 27) fixed at the end of the control rod (24)
15. Machine tool according to Claim 13 or 14, characterised in that the control volume (26) can be vented via a ventilating device (28).
16. Machine tool according to one of Claims 11 up to 15, characterised in that the hydraulic connection between the accumulator space (18) and the working chamber (16) is made as a cross hole (17) located inside the machine casing (6), which is accessible from outside and can be used for refilling oil.
17. Machine tool according to one of Claims 11 up to 16, characterised in that the plunger piston (9) is located on the same axis as the working piston (2) and can be actuated via a pneumatic piston (11) against a returning force.
18. Machine tool according to Claims 1 up to 10, characterised in that the pressure generator features an accumulator space (18) that is coaxial towards the plunger piston (109), whereby the common longitudinal axis is aligned parallel to that of the differential piston (101) with a pressure channel connecting the pressure generator with the working chamber (116), whereby, at the end of the working stroke and corresponding inflow of fluid from the accumulator space (118) into the working chamber (116), the plunger piston (109) closes the pressure channel, after which further motion of the plunger piston (109) inside the working chamber (116) develops high pressure.
19. Machine tool according to one of the preceding claims, characterised in that the working piston (2, 102) features a head piece (36) towards its free end, in or on which control elements such as the piston collar (31) and similar elements (bypass channels 38, 39) are located and separably connected with the differential piston (1, 101).

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