EP0441725B1 - Gas-spring powered clamping device for various workpieces - Google Patents

Description

The present invention relates to the immobilization of various parts on trays, plates, working or machining tables or on any other similar support with respect to which any part must be firmly immobilized temporarily.

As a preferred application, the invention relates to the immobilization of work pieces on machine tool tables.

The immobilization of parts on any support is generally carried out by direct or indirect mechanical clamping.

By indirect clamping, it is necessary to consider the adaptation on the support of a clamping piece in or on which the piece to be immobilized is adapted.

By direct clamping, it is advisable to consider the immobilization of the part itself directly on the table, by means of flanges exerting a clamping action of the part on the support.

The invention relates to direct clamping.

The flanges, used to ensure direct immobilization, are, generally, of the mechanical type and most often comprise an anchoring foot of the lardon type, capable of being fitted into a groove, of the Tee type, presented by the support. The mechanical flange comprises, in elevation from the foot, a sort of tie rod or the like, or even a body supporting a movable jaw whose position can be adjusted by a screw or toggle control.

The blocking of the part to be immobilized by means of a toggle joint device is not satisfactory, due to the relatively low pressure likely to be exerted.

A screw control ensures immobilization capable of withstanding high stresses, but its relatively long commissioning does not allow adaptation in work sequences with high intervention frequencies. In addition, the clamping force is only dependent on the manual action. of the operator, so that variable pressure constraints can intervene with all the damaging consequences likely to be attached to a tightening that is too weak or too strong.

In all areas where the immobilization of a part must be ensured, the need has therefore been felt to have a clamping flange which can be actuated quickly in clamping and unclamping, capable of exerting a clamping force. known and constant on the part to be immobilized, simple and robust design and certain reliability.

To meet this need, the prior art has advocated the use of hydraulically controlled flanges. In this regard, it should be mentioned, in particular, the patents US-A-4,504,046 and US-A-4,721,293 and the patent DE-C-3,736,421 each comprising, in a support body, a hydraulic piston with double effect whose rod acts, by a corner, on a ramp controlling the actuation of a clamping jaw guided in the body.

Such solutions certainly represent an appreciable development which, however, is not yet entirely satisfactory for the following reasons.

If the hydraulic flanges have a speed of action greater than that of the mechanical flanges, on the other hand, they require to be permanently connected to two hydraulic circuits whose size is always inconvenient. Such dependence removes any possibility of autonomous use.

The supply of hydraulic clamping pressure must be maintained throughout this phase, which leads to a certain energy expenditure, for a period equivalent to that of the clamping phase.

Since the hydraulic clamping pressure is applied for long periods of time, it is imperative to build the flange with high quality components, able to resist durably, without leakage to the imposed stress. This requirement certainly raises the cost of manufacturing, but also of maintaining such flanges.

It is also known, from document EP 0 087 041 corresponding to the preamble of claim 1, a clamping flange comprising a flange body delimiting a cylinder and arranged to delimit a connecting and anchoring foot. The flange also includes a piston housed in the cylinder in which it delimits two chambers with inversely variable volumes, the first chamber being provided with a spring acting to move the piston in the direction for which a clamping action takes place between the jaw and the foot, while the second chamber is in connection with a connection fitting with a circuit capable of delivering, in said chamber, in a controlled manner, a fluid pressure developing a force greater than that generated by the spring. Furthermore, the flange has a clamping jaw partly associated with the piston.

The present invention aims to solve the above drawbacks by proposing an autonomous clamping flange, produced in the form of an elementary assembly, functionally autonomous, which can be adapted to all fields of application, whenever it is necessary. to temporarily immobilize a part or any object on a support.

• un corps de bride délimitant un cylindre,
• un pied de liaison et d'ancrage porté par le corps,
• un piston logé dans le cylindre, dans lequel il délimite deux chambres à volumes inversement variables, la première chambre étant pourvue de moyens agissant pour déplacer le piston dans le sens pour lequel intervient une action de serrage entre un mors de serrage et le pied, tandis que la seconde chambre est en relation avec un raccord de liaison avec un circuit à même de délivrer, dans ladite chambre, de façon commandée, une pression de fluide développant une force supérieure à celle générée par les moyens de déplacement du piston, équipant la première chambre,
• et le mors de serrage est associé en partie au piston.

To achieve the above objectives, the object of the invention relates to an independent clamping flange, for various parts, of the type comprising:

• a flange body delimiting a cylinder,
• a connecting and anchoring foot carried by the body,
• a piston housed in the cylinder, in which it delimits two chambers with inversely variable volumes, the first chamber being provided with means acting to move the piston in the direction for which a clamping action takes place between a clamping jaw and the foot, while that the second chamber is in relation to a connection fitting with a circuit capable of delivering, in said chamber, in a controlled manner, a fluid pressure developing a force greater than that generated by the means of displacement of the piston, equipping the first bedroom,
• and the clamping jaw is partly associated with the piston.

• les moyens pour déplacer le piston sont constitués par une charge de fluide gazeux sous pression, confinée par la première chambre constituée sous la forme d'une capacité fermée,
• et en ce que le mors de serrage est associé, en partie, au piston par l'intermédiaire d'un système de commande du type à coin.

According to the invention, the clamp is characterized in that:

• the means for moving the piston are constituted by a charge of gaseous fluid under pressure, confined by the first chamber constituted in the form of a closed capacity,
• and in that the clamping jaw is associated, in part, with the piston via a wedge type control system.

Various other characteristics will emerge from the description given below with reference to the accompanying drawings which show, by way of examples, embodiments of the subject of the invention.

Fig. 1 is a sectional elevation of a first embodiment of the flange according to the invention.

Fig. 2 is a transverse view taken along line II-II of FIG. 1 .

Fig. 3 is a sectional elevation of another form of realization of the flange according to the invention.

Fig. 4 is a sectional elevation of another embodiment of the object of the invention.

Figs. 5 to 7 are sections taken, respectively, along the lines VV to VII-VII of FIG. 4 .

Fig. 8 is a partial section taken on the line VIII-VIII of FIG. 7 .

Fig. 9 is a perspective, in exploded view, illustrating the particular conformation of two constituent elements of the example according to FIGS. 4 to 8 .

Figs. 1 and 2 show a first embodiment of an independent gas clamping clamp 1 designed, according to the invention, to immobilize a part 2 relative to a support 3 , illustrated in the form of a machine tool table . Conventionally, such a table has, from place to place, grooves 4 , of the inverted tee type, which are used to ensure the adaptation of the flange 1 . To this end, the flange 1 comprises a body 5 which forms directly at its base a connecting and anchoring foot 6 of the lardon type, capable of being engaged in a groove 4 of complementary profile.

The body 5 preferably has a gallows shape and has an upper part 7 extending in overhang from the body 5 and parallel to the foot 6 . The upper part 7 defines a closed cylinder 8 , in particular by a plug 9 , removable or not. The cylinder 8 communicates, by its bottom, with a concentric bore 10 opening out inside a blind housing 11 opening onto the face of the terminal part 7 oriented in the direction of the foot 6 .

The cylinder 8 contains a piston 12 delimiting, inside the cylinder 8 , two chambers with inversely variable volumes 13 and 14 . The piston 12 , capable of sliding with sealing inside the cylinder 8 , is extended by a rod 15 sliding with sealing in the bore 10 . The rod 15 forms at the end a protruding wedge 16 in the housing 11 to cooperate with a ramp 17 formed by a clamping jaw 18 , capable of slide in the housing 11 . In this example, the sliding direction xx ′ of the clamping jaw 18 is perpendicular to the sliding direction yy ′ of the piston 12 . The clamping jaw 18 is, preferably, projecting continuously from the lower face 7a and can be retained within the housing 11 by any appropriate technical means, such as a shoulder, a ring or a member elastic return, such as 18 a .

The ramp 17 can be formed directly by the jaw 18 or, preferably, by a ball joint 19 , of spherical or substantially semi-cylindrical type, placed in a complementary cavity presented by the jaw 18 to offer the ramp 17 in cooperation with corner 16 .

According to the invention, the chamber 13 constitutes a closed capacity in which is confined a charge of fluid, preferably gaseous, under pressure, for example introduced via a valve plug 20 closing a conduit 21 opening into the chamber 13 .

The chamber 14 of the cylinder 8 communicates with an extended conduit 22 , externally to the body 7 , by a connector 23 , preferably of the quick type, making it possible to connect the chamber 14 to a circuit 24 capable of delivering, in a controlled manner, a pressure fluid, preferably hydraulic, developing in the chamber 14 an antagonistic force greater than that generated in the chamber 13 by the gas charge.

Preferably, the ramp 17 makes, with respect to a plane PP ′ perpendicular to the axis xx ′ , an angle α complementary to the angle α ′ presented by the corner 16 . The angles α and α ′ are of the non-reversible actuation type, that is to say that the displacement of the piston 12 , in the direction of the arrow f₂ , produces the sliding of the clamping jaw 18 in the clamping stroke in the direction of the arrow f₁ , without a reverse mutual actuation being able to intervene.

Insofar as this condition is not met, it can be envisaged to have, in the chamber 13 , an elastic member 25 working under compression, always urging the piston 12 in the direction of the arrow f₂ .

The operation of the flange described above takes place as follows.

When it is appropriate to place the part 2 on the support or the table 3 , the flange is connected, by the connector 23 , to the source 24 which delivers, in the chamber 14 , a fluid under pressure greater than that of confinement of the gas charge inside the chamber 13 . The piston 12 is thus biased in the opposite direction to that of the arrow f₂ , so that the erasing of the clamping jaw 18 can intervene, directly or indirectly.

Such a phase occurs, preferably, after adaptation of the flange 1 on the table 3 , by cooperation between the foot 6 and at least one of the grooves 4 .

When the part 2 has been placed in the required position, the fluid source 24 is disconnected from the connector 23 to release the pressure prevailing in the chamber 14 . The charge of gas confined in the chamber 13 then causes the piston 12 to move in the direction of the arrow f₂ . The corner 16 acts on the ramp 17 which pushes the jaw 18 in the direction of the arrow f₁ , so as to exert a clamping action between the jaw and the foot 6 to clamp the part 2 between the table 3 and the jaw 18 .

The clamping action is exerted by the flange 1 independently, due to the charge of pressurized fluid trapped in the chamber 13 . The immobilization of the part 2 therefore remains effective, without requiring any intervention from an operator, as long as a connection to the source 24 is not established.

It should be noted that the flange according to the invention has a wedge and ramp mechanism of the irreversible type which makes it possible to maintain a relative clamping force, even if the gas pressure drops accidentally in the chamber 13 .

The clamping mechanism, via the corner 16 and the jaw 18 , provides a stiffening stiffness which has a certain advantage, in the case where the immobilization of the part 2 must undergo relatively large dynamic forces, even generating vibrations.

The energy required for unlocking, provided by the source 24 , involves a high relative pressure which is only applied to the flange in the unclamping phase.

In addition to the energy saving achieved, this form of actuation makes it possible to reduce the high pressure which would ordinarily be necessary if the clamping action intervened by connection between the chamber 13 and the source 24 , in replacement of the on-board gas charge. .

The application of the release pressure takes place in a generally very short time, so that the flange is only very slightly stressed by this pressure and can therefore be produced in a reliable and robust manner, without involving mobile equipment. of very high technical characteristic, able to work efficiently and durably at the release pressure.

Another embodiment is illustrated in FIG. 3 in which the piston rod 15 is extended by the wedge 16 which acts on an indirect type clamping system. In this example, the wedge 16 acts on a jaw 18₁ , internal to the housing 11 , which is closed by a plug 30 for possible guidance of this jaw.

A tie rod 31 is supported on the jaw 18₁ opposite the ramp 17 . The tie freely crosses the jaw 18₁ , the corner 16 by a notch 32 and the body 5 which has a heel 33 forming the jaw 18 of the previous example, in association with the jaw 18₁ . Externally to the body 5 , the tie rod has a foot 6 capable of cooperating with a groove 4 . The support of the tie rod on the jaw 18₁ is preferably provided by a threaded end piece 34 allowing the useful length of the tie rod 31 to be adjusted.

The clamping action of the part 2 on the support 3 occurs, as before, by the action of the gaseous charge pushing the piston in the direction of the arrow f₂ . The corner 16 acts on the ramp 17 to lift the jaw 18₁ which carries with it the tie rod 31 immobilized by the foot 6 in the groove 4 . A relative downward movement of the body 5 is, in this way, produced with application of the static jaw 33 on the part 2 pressed on the table 3 .

In this example, the corner 16 is extended by a finger 36 , capable of projecting from the body 5 , to constitute a visual witness to the state of clamping or unclamping of the flange.

A preferred embodiment of the object of the invention is illustrated in FIGS. 4 to 9 in which the same references designate the same constituent elements as those described above.

In this example, the clamping jaw 18 , the general plane of which is perpendicular to the axis yy ′ , is produced in the form of a solid piece forming the nose 41 . The jaw 18 comprises, opposite a bearing heel 43 , a convex profile 44 cooperating with a complementary wall 11b of the housing 11 . Opposite the nose 41 , the jaw 18 has an edge 45 for adapting an elastic member 46 working in traction and responsible for bringing the jaw 18 back into a retraction position relative to the housing 11 .

The end portion of the jaw 18 , opposite the nose 41 , has, below the edge 45 , two inclined ramps 47 and 48 which occupy different planes corresponding to two orthogonal control directions perpendicular to the axis xx ′ . The ramps 47 and 48 are intended to cooperate with two complementary ramps 49 and 50, respectively formed by the wedge 16 which can be formed directly by the piston rod 12 or by an independent part, as shown in FIG. 9 .

Under the action of the fluid charge occupying the chamber 13 , the piston 12 is moved, in the direction of the arrow f₂ , so that the corner 16 comes to cooperate, firstly, by the ramp 49 with the ramp 47 of the bit 18 .

As appears from the comparison of FIGS. 7 and 8 , the movement in the direction of the arrow f₂ causes the extension of the nose 41 outside the body 5 , in a direction which is perpendicular to the axis yy ′ . Secondly, the cooperation of the ramp 50 with the ramp 48 causes the jaw 18 to tilt or pivot, simultaneously with its extension stroke, by pressing on the heel 43 with concomitant guidance, by cooperation of the profile 44 with the wall 11 b .

The action of the piston 12 therefore produces, in a first time, an extension stroke bringing the outlet of the nose 41 out of the body 5 then, by pivoting-tilting, the clamping of the part 2 between the nose 41 and the support or the table 3 .

The movement of the jaw 18 occurs, as said above, against the action of the elastic member 46 which brings the jaw back to the original position, as soon as the piston 12 is driven in the opposite direction to that of the arrow f₁ , by connection of the chamber 14 with the source of pressurized fluid 24 .

In this exemplary embodiment, provision may be made to adapt, on the body 5 , a manual control 51 making it possible to cause, if necessary, the stroke of the piston 12 in the opposite direction to that of the arrow f₂ .

Claims (7)

1. A self-sustaining gripping clamp for various items, of the type comprising:

   - a retaining body (5) defining a cylinder (8),

   - a linking and anchoring foot (6) carried by the body,

   - a piston (12) accommodated in the cylinder, in which it defines two chambers (13,14) of inversely variable volume, the first chamber (13) being provided with means acting to displace the piston (12) in a direction in which a gripping action takes place between a gripping jaw (18) and the foot (6), while the second chamber (14) is in communication with a connection (23) to a circuit (24) which can supply a fluid pressure to said chamber in a controlled manner, the fluid pressure developing a force greater than that generated by the piston displacement means of the first chamber,

   - and the gripping jaw (18) is partly associated with the piston,

      characterised in that:

   - the means for displacing the piston (12) comprise a charge of gaseous fluid under pressure, confined by the first chamber (13) which is in the form of a closed capacity,

   - and that the gripping jaw (18) is partly associated with the piston via a control system (16,17) of the wedge type.
2. A gripping clamp according to claim 1, characterised in that the piston (12) acts on the jaw (18) through a wedge (16) and slope (17) mechanism, the angles (α and α') of which make actuation irreversible.
3. A gripping clamp according to claim 1 or 2, characterised in that the jaw (18) is mounted so that it can move in a direction different from the direction (y - y') of displacement of the piston (12).
4. A gripping clamp according to claim 1,2 or 3, characterised in that the jaw (18) can move along a curved path.
5. A gripping clamp according to any of claims 1 to 4, characterised in that the jaw (18) has a rust slope (47) to control the movement of extension out of the body against the action of a resilient member (46), and a second slope (48) for control by pivoting during the gripping movement, both for interaction with the wedge (16).
6. A gripping clamp according to claim 5, characterised in that the wedge (16) has a first slope (49) designed to interact with the slope (47) on the jaw in order to control extension of the jaw out of the body (5), and a second slope (50) designed to interact with the slope (48) on the jaw in order to control movement along the gripping curve.
7. A gripping clamp according to claim 5 or 6, characterised in that the jaw (18) comprises a solid component which forms a bearing heel (13) at its base, a convex section (44) opposite it, interacting with a mating wall (11b) of the seat (11) for the jaw, a projection (41) at one end and, at the opposite end, firstly the slopes (47 and 48) and secondly a means for interaction with a resilient return member.

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