Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
  • B30B15/16—Control arrangements for fluid-driven presses
  • B30B15/161—Control arrangements for fluid-driven presses controlling the ram speed and ram pressure, e.g. fast approach speed at low pressure, low pressing speed at high pressure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B1/00—Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen
  • B30B1/007—Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen using a fluid connection between the drive means and the press ram

Definitions

• the present invention relates to a hydraulic press mechanism and, more particularly, a mechanism making it possible to successively obtain a rapid approach stroke, then a working stroke with significant developed force, for operations such as riveting, marking, clamping and, more generally, for all operations in which the working stroke can be relatively short compared to the magnitude of the approach movement.
• Hydraulic press mechanisms currently known often consist of a single movable piston. To have an approach stroke, it is necessary in this case to move all the more hydraulic fluid that this stroke is important. This cannot be done essentially. only by a pump, therefore by a complex device compared to the simplicity of the cylinder itself. If the fluid is moved by a manual pump, this is done at the cost of numerous maneuvers which, naturally, make the operation slow and inconvenient. Certain known devices allow a large and rapid approach movement, but for this require a second cylinder and corresponding distribution chambers for conveying the fluid. Certain existing presses allow a fast approach stroke by the high flow rate of a low pressure pump, and a slow working stroke by the weak relief stroke of a high pressure pump The supply and control device is in the latter costly case, vis-à-vis the desired result.
• the invention also aims for other results, in particular entirely hydraulic operation, by allowing automatic compensation for variations in the volume of the fluid, for example linked to functional leaks in the seals, these leaks becoming sensitive when the device has made a few hundred thousands of operations and when using a very fluid oil to have a high operating speed.
• the invention mainly relates to a hydraulic press mechanism comprising a rod, on which the control action of the device is exerted, and a main body, displaceable along a same axis in a fixed guide bore, means being provided for the non-permanent locking of the body with respect to the rod, said body comprising a chamber filled with incompressible fluid, into which a primary piston extending said rod penetrates, this chamber communicating on the one hand with an expandable sleeve axially immobilized around the body and able to be pressed against the wall of the aforementioned bore, so as to block the body with respect to the bore, and on the other hand with a cylindrical chamber in which is slidably mounted a secondary piston, the latter being attached to a work tool and subject to the action of a return spring.
• the mechanism thus defined is capable of causing the tool to describe an approach stroke followed by a working stroke, while being controlled only by a member called here rod, the working stroke being triggered when the tool comes into contact with the part to be pressed.
• This result is obtained by blocking the main body in the bore, by means (expandable sleeve) coming into operation when the tool, coming into contact with the part to be pressed, causes an axial displacement of the rod relative to the body. , which allows the primary piston to pressurize the fluid circuit, causing on the one hand the inflation of the expandable sleeve, and on the other hand the advance of the secondary piston which then makes the tool describe its stroke job.
• the control rod and the body advance simultaneously, thanks to the temporary locking effect, for example, by means of a calibrated valve which closes the lower part of the first hydraulic chamber and thus prohibits to the incompressible fluid to exit therefrom, in the direction of the expandable bushing and of the second chamber, and thereby preventing the primary piston from entering this first chamber, so that the control rod in its movement drives the entire body, and in particular the secondary piston, until the tool fixed to the latter comes into contact with. the object to be pressed.
• the body immobilizing it suffices that the primary piston continues to be pushed in so that it forces the valve to open by the pressure it creates in the chamber.
• the control rod continues its stroke, the piston moves pressurized oil past the tared valve to the expandable bushing and. towards the secondary piston.
• the flexibility of the sleeve is such that it inflates and locks the body with respect to the bore, before the secondary piston, held in particular by its spring, advances with the much desired force.
• the valve by the resistance which it offers to the flow of the fluid, opposes the insertion of the primary piston into the body, and this results in a permanent effort which makes it possible to maintain an energetic contact between the tool and the object to be pressed during the entire swelling phase of the sleeve, regardless of the position in the space of the device.
• the significant force of the secondary piston is advantageously obtained by a "multiplication" effect provided by the incompressible fluid itself, by providing that the chamber of the body, in which the secondary piston slidingly mounted integral with the tool, has a section larger than that of the primary piston linked to the control rod
• the force exerted on the tool must remain less than the force blocking the body in the bore-
• control rod is brought back, which conversely first causes the secondary piston to retreat and the main body to be released relative to the bore, then the simultaneous retraction of the rod and body, the aforementioned valve being designed in such a way that it lets the fluid flow back easily to the chamber from which it came.
• the primary piston advantageously comprises, at its end which plunges into the chamber filled with fluid, a groove such that, when this primary piston is in position tion retracted, and only in this position, said groove puts the body chamber into communication with a reserve of hydraulic fluid, delimited by the bore in which the body slides and by a movable wall in said bore and pushed by a spring, to monitor fluid level variations without risk of air entering the hydraulic circuit.
• the variations in volume of the fluid contained in the useful part of the hydraulic circuit are thus automatically compensated for from a cylindrical chamber, constituting a reserve.
• control of the rod integral with the primary piston which is in fact the only control of the entire device, can be carried out mechanically, according to a first possibility, by providing that the control rod is provided with a rack in engagement with a drive pinion, the latter being mounted on a shaft maneuvered by a member such as a lever, possibly by interposing a torque limiter.
• the general control is pneumatic or hydraulic.
• the whole mechanism can then be arranged along the same axis, providing that the frame comprises a cylinder, co-axial with the bore in which the body slides, an additional piston integral with the primary piston being slidably mounted in said cylinder, constituting a pneumatic or hydraulic control cylinder.
• a control tube linked to the primary piston, mounted to slide and rotate in a bore of the frame is linked by a thread to the body which means immobilize in rotation, the approach stroke being / obtained by simultaneous translation of the tube and the body, while the working stroke is obtained by screwing the tube onto the body, said tube being operable by a suitable part, preferably by means of a torque limiter-In the latter
• the thread ensures, during the approach movement, the axial connection between the tube and the body, and during the working stroke, an amplification of the force.
• Pigures 1,2, 3 and 4 are sectional views of the mechanism according to the invention, in four successive positions, illustrating its operating principle;
• Figure 5 is a partial view, in section and on an enlarged scale, of a variant with mechanical locking by ball of the primary piston relative to the body;
• Pigure 6 is a sectional view of the mechanism according to the invention, in another variant where the control of the rod is done by an additional piston driven by compressed air or any other fluid;
• Pigure 7 is a view, partially in section, of a final embodiment, with control by combined translation and rotation;
• Pigure 8 is a section along 8-8 of Figure 7.
• FIGS. 1 to 4 represent a machine comprising a frame 1, on which a tube 2 of vertical axis 3 is fixed.
• a body 9 which carries an expandable sleeve 19, which is immobilized axially on the one hand by a shoulder separating the two parts of distinct diameters from the body 9, and on the other hand by an annular stop member 20.
• the body 9 is hollowed out, so as to comprise an upper cylindrical chamber 10 connected, by an intermediate channel 11, to a lower cylindrical chamber 12.
• At least one radial communication 21 connects the channel 11 to the inside of the sleeve 19, which is filled with incompressible fluid, in particular oil.
• Chamber 12 contains a secondary piston 15 secured to a tool 16 passing through a screwed bottom 17, a spring 18 being compressed between this bottom 17 and the lower face, of the secondary piston 15.
• the upper chamber 10, the channel 11 and the part of the lower chamber 12 situated above the secondary piston 15 are filled with the same incompressible fluid as the expandable sleeve 19.
• a primary piston 8 which has on its lower part a longitudinal groove 26 of a length such that, when the piston 8 is in the high position (shown in FIG. 1), this groove 26 puts the communication chamber 10 and a chamber 35 filled with the same incompressible fluid and located above the body 9.
• the chamber 35 constituting a reserve of fluid, is separated from the chamber 10 by a seal 14, retained by a ring 13 screwed to the top of the body 9 (the gasket 14 not fulfilling its function in the high position of the piston 8).
• the chamber 35 is delimited again by another seal 7 interposed between the body 9 and the tube 2, by the inner wall of this tube 2, and by a movable upper bottom 22, which is kept applied against the surface of the liquid by means of a spring 23.
• the rod 4 is provided with a rack 5, engaged with a drive pinion 6 mounted on a maneuvered shaft, for example, using a lever not shown.
• a double valve device which temporarily closes the inlet of the intermediate channel 11 located at the bottom of the chamber 10, and in doing so opposes the penetration of the primary piston 8 into said chamber 10.
• one of the valves is arranged at the inside of the other: a first valve 29, pushed down by a spring 30, serves as a housing for a second valve 31, biased upwards by another spring 32.
• the part 25 to be worked, for example to be flattened, is placed on the frame l ⁇ in axis 3 of the device described above.
• the secondary piston 1 5 is moved downwards in the chamber 12 of the body 9 which remains immobilized and it pushes the tool 16 against the part 25 to press (see figure 3).
• the section of the secondary piston 15 is such that the force P resulting from the pressure applied to this piston remains slightly less than the blocking force of the body 9 relative to the tube 2.
• This force F due to the fact that the section of the secondary piston 15 is larger than that of the primary piston 8, will on the other hand be higher than the force applied to the rod 4 which is good, the desired effect (obtaining a low working stroke with high developed force).
• the rod 4 After having thus carried out the flattening operation, or the like, on the part 25, the rod 4 is brought up by a reverse rotation of the pinion 6.
• the primary piston 8, rising with the rod 4, causes the pressure to drop. on the secondary piston 15.
• the latter returns back into the chamber 12 under the upward return action exerted by the spring 18.
• the drop in pressure inside the expandable sleeve 19 causes it to contract.
• the sleeve thus makes the body 9 free to move relative to the tube 2.
• the fluid flowing back from the sleeve 19 and from the chamber 12 of the secondary piston 15 lifts the valve 29 and thus passes around it in the direction of the next chamber 10 the path defined by the arrows 34 ( Figure 4).
• the primary piston 8 thanks to the shoulder which it also has at its lower part, carries with it upwards the body 9 which thus returns to its starting position.
• the valve 29 resumes its rest position by closing the entrance to channel 11. The device is thus ready to perform another work cycle.
• the temporary connection between the primary piston 8 and the body 9 is made thanks to a mechanical locking, with ball for example and constituted in this case by a ball 42 housed in a bore formed radially in the lower part of the piston 8 and also receiving a spring 43 which tends to push the ball 42 towards the outside of its housing.
• this ball 42 is partially housed in a groove 44 of an annular part 45 placed under the seal 14 and which is fixed relative to the body 9.
• the displacement of the rod of the primary piston 8 is obtained by means of an additional piston 36, fixed to the upper part of the piston ⁇ B and mounted to slide inside.
• a cylinder 37 placed along the axis 3 in the upper region of the tube 2 which serves as a guide for the body 9 as well as a bearing surface for the expandable do ⁇ ille 19. This cylinder 37 is closed at its upper part by a cover 38.
• the piston 36 is driven by a pneumatic or hydraulic fluid, admitted into the upper cha ⁇ rre of the cylinder 37 by an orifice 39 of the cover 38, and it is brought back to the rest position by a spring 40 housed in the lower chamber of the cylinder 37, or well by any fluid introduced into this same chamber through an orifice 41.
• the assembly thus produced constitutes a jack with rapid advance and multiplication of force at the end of the stroke, an important advantage of which is that, whatever the position of the part to be pressed 25 relative to the frame 1 (within the limit of the stroke of the body 9), the final force exerted will be the same and will depend directly on the pressure of the control fluid acting on the piston 36.
• a tube 4 is linked to the body 9 by a thread 47, these two members being slidably mounted in a bore 2 of the frame 1.
• the body 9 is here immobilized in rotation relative to the frame 1, for example by means of a screw 48 engaged in a groove 49 of the body 9.
• The. tube 4 can on the contrary rotate around the axis 3, and it is maneuverable by means of a part 50 mounted at its top.
• This part 50 is linked in rotation with the tube 4 by a torque limiting device, which comprises: a ball 51 housed in a radial bore of the part 50; an internal groove 52 of the tube 4;
• the tube 4 maneuvered using the part 50, is rotated and therefore screwed onto the body 9, which remains immobilized in rotation.
• the tube 4 sinks into the bore 2 and it drives with it, downwards, the primary piston 8 secured to said tube.
• the descent of the piston 8 in the hydraulic circuit increases the pressure in the latter and has the effect, on the one hand, of blocking the body 9. relative to the frame, by inflation of the expandable bush 19, and d on the other hand, to make the tool 16 move against the piece to be pressed 25.
• the torque limiting device associated with the piece 50, makes it possible to limit the pressing force of the tool 16 on the piece 25.
• This last embodiment allows, with a relatively low screwing torque, and exerted for example by hand, to obtain an already amplified force on the primary piston £ 3, by the effect of the thread 47, this force being at its turn amplified by the secondary piston 15 pushing the tool 16.
• the press mechanism described above finds applications in particular in the field of marking and riveting, and it can be controlled, depending on the energy sources available and the efforts to be made , by manual, mechanical, hydraulic, pneumatic or other actuation means, acting on the rod 4. Other applications can be envisaged in the clamping field, where rapid advance, followed by effort significant tightening, is often sought.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Press Drives And Press Lines (AREA)
• Steering Control In Accordance With Driving Conditions (AREA)
• Actuator (AREA)
• Automatic Assembly (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9239754

Family Applications (1)

Country Status (12)

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Family Cites Families (14)

• 1980
  • 1980-03-12 FR FR8005955A patent/FR2477960A1/fr active Pending
• 1981
  • 1981-03-11 EP EP81900640A patent/EP0046788B1/de not_active Expired
  • 1981-03-11 BR BR8107434A patent/BR8107434A/pt unknown
  • 1981-03-11 JP JP56500832A patent/JPS57500275A/ja active Pending
  • 1981-03-11 AU AU67834/81A patent/AU547086B2/en not_active Ceased
  • 1981-03-11 DE DE8181900640T patent/DE3162570D1/de not_active Expired
  • 1981-03-11 AT AT81900640T patent/ATE6610T1/de not_active IP Right Cessation
  • 1981-03-11 US US06/317,902 patent/US4499728A/en not_active Expired - Fee Related
  • 1981-03-11 WO PCT/FR1981/000034 patent/WO1981002543A1/fr active IP Right Grant
  • 1981-04-07 CA CA000374820A patent/CA1163900A/fr not_active Expired
  • 1981-11-11 NO NO813816A patent/NO152997C/no unknown
  • 1981-11-12 DK DK502081A patent/DK502081A/da not_active Application Discontinuation

Non-Patent Citations (1)

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