Clamping device

Abstract

Clamping device (D), comprising a jack (1) and a flange (2), the jack (1) being selectively actuated by a pressurized fluid and itself comprising a body (10) fixed in operation to the tooling, and the flange (2) moving between a clamping position and a release position, characterized in that the clamping device (D) comprises detection means configured to detect when the flange (2) is moving from the release position to the clamping position, these detection means comprising an orifice (6) configured to be closed by the flange (2), said orifice (6) being continued by an air supply channel.

Description

[0001] The invention relates to a clamping device having a small footprint. More specifically, the invention relates to a device configured to clamp a part on a tool during a machining operation, for example.

[0002] In fact, the invention is a device of the type comprising a jack and a clamp actuated by the jack, said clamp being able to move from a position for clamping a part to be clamped to a release position for which the clamp is in the retracted position. This release position makes it easier to place or remove the part to be clamped on said device.

[0003] Such an example of a clamp is presented in document EP1697088B1. It describes a device for clamping a part on a tool, comprising a cylinder and a clamp, the cylinder being selectively actuated by a pressurized fluid and itself comprising a body fixed in operation to the tool and a rod movable relative to the body, and the clamp being articulated around a pivot axis on the rod and selectively driven by the rod, this clamp moving over a determined stroke between a clamping position and a release position, and undergoing rotation over at least part of its stroke.

[0004] In fact, document EP1697088B1 presents a device for clamping a part on a tool, comprising a jack and a flange, the jack being selectively actuated by a pressurized fluid and itself comprising a body fixed in operation to the tool and a rod movable relative to the body, and the flange being articulated around a pivot axis on the rod and selectively driven by the rod, this flange moving over a determined stroke between a clamping position and a release position, and undergoing rotation over at least part of its stroke.This device further comprises guide members and support elements, these guide members comprising a guide member fixed relative to the body and a movable guide member connected to the flange, these fixed and movable guide members cooperating to drive the flange in a rotational movement around the pivot axis at least at the end of its travel towards its release position and in a translational movement at least at the end of its travel towards its clamping position. In addition, these support elements comprise a support element fixed relative to the body and a movable support element connected to the flange, these fixed and movable support elements cooperating selectively, at least at the end of the travel of the flange towards its clamping position, to offer each other, at a distance from the guide members, a sliding contact parallel to the translational movement of the flange and allowing the flange to be buttressed on the part to be clamped.

[0005] The device thus described therefore comprises a flange passing from a clamping position to a release position and vice versa by successive and combined translational and rotational movements.

[0006] This clamping device has the advantages of being compact, fast, retractable, powerful, and, in addition, with a clamp that is not very prone to buckling.

[0007] However, despite all these advantages over other existing clamps, such a device still has disadvantages.

[0008] A first disadvantage lies in the fact that such a device has openings through which the mechanisms of the device are visible and accessible through which machining chips, dust, fluids of all kinds can enter.

[0009] This can cause seizures during operation of the clamping device.

[0010] It may be possible to protect the device with a silicone bellows covering the housings, openings and crevices, but this is detrimental to the compactness of the clamping device. In addition, the complex movement of the clamp does not allow for good coverage with this type of protection. Finally, this type of elastomer bellows type protection can deteriorate rapidly under the action of chemical aggression from the fluids in contact as well as contact with hot chips.

[0011] A second disadvantage is that the clamp of the device must move from a release position to a clamping position quickly under the action of a pressurized fluid actuating the cylinder, therefore with a rapid fluid flow rate. But it is also necessary for the clamp to come into the clamping position on a part to be clamped with sufficient clamping force, but below a determined maximum threshold, for example to prevent the clamping force from damaging the part to be machined, which requires very fine adjustment of the pressure of the pressurized fluid actuating the cylinder, with a slower fluid flow rate.

[0012] To meet these two requirements, it is necessary for the device to be able to switch from a fast pressurized fluid flow to a slower flow and vice versa at a given moment which can vary depending on the flange and the stroke of the cylinder. To determine this moment, one can seek to precisely detect the position of the device's flange in its stroke taking it from the release position to the clamping position of the part to be clamped. To do this, the device can be equipped with a flange displacement detector, but this is an expensive additional piece of equipment which must be electrically powered. This is detrimental to obtaining a simple device to produce.

[0013] A third disadvantage is that the clamp of the device has a nose whose flat end is configured to rest against a surface of the part to be clamped. Sometimes the surface is not parallel to the flat end of the nose. In this case, the nose rests on the part only occasionally, and the part may slip or the surface may be marked by the nose.

[0014] In this context, the invention aims to propose an improved clamping device having, as a preamble, the characteristics of the clamping device described above but free from all or part of the defects previously mentioned.

[0015] To this end, the invention relates to a device for clamping a part on a tool, comprising a jack and a flange, the jack being selectively actuated by a pressurized fluid and itself comprising a body fixed in operation to the tool and a rod movable relative to the body, and the flange being articulated around a pivot axis on the rod and selectively driven by the rod, this flange moving over a determined stroke between a clamping position and a release position, and undergoing rotation over at least part of its stroke, this device further comprising guide members and support elements, these guide members comprising a guide member fixed relative to the body and a movable guide member linked to the flange,these fixed and mobile guide members cooperating to drive the clamp in a rotational movement around the pivot axis at least at the end of its travel towards its release position and in a translational movement at least at the end of its travel towards its clamping position, and these support elements comprising a support element fixed relative to the body and a mobile support element linked to the clamp, these fixed and mobile support elements cooperating selectively, at least at the end of the travel of the clamp towards its clamping position, to offer each other, at a distance from the guide members, a sliding contact parallel to the translational movement of the clamp and allowing the clamp to buttress the part to be clamped.

[0016] Advantageously, this clamping device comprises at least one covering hood comprising two ends, a first end cooperating with the flange by a pivoting connection, a second end cooperating with the body by a translational connection.

[0017] This makes it possible to offer a clamping device that remains compact while providing simple and economical protection against seizing elements, this protection being able to follow the complex movements of the clamp.

[0018] According to a feature of the invention, the first end of the covering hood(s) comprises two shafts originating from the hood and extending laterally in opposite directions, cooperating by fitting into reciprocal bearings of the flange to form pivoting connection means.

[0019] According to another feature of the invention, the second end of the covering hood(s) has lateral edges configured to slide in facing slides of the body to form translational connection means.

[0020] This proposed protection is easy to mount on the clamping device.

[0021] According to another feature of the invention, the at least one covering hood comprises an elastically deformable part.

[0022] This allows the movements of the bridle to be followed even more precisely.

[0023] According to another feature of the invention, this clamping device comprises a covering hood whose elastically deformable part has a configuration without deformation when the clamp is in the clamping position, and which has a deformed configuration when the clamp is in the release position.

[0024] According to another feature of the invention, this clamping device comprises a covering hood whose elastically deformable part has a configuration without deformation when the clamp is in the released position, and which has a deformed configuration when the clamp is in the tightened position.

[0025] According to yet another feature of the invention, the clamping device comprises detection means configured to detect when the clamp is in translation only during the movement of the clamp from the release position to the clamping position, these detection means comprising an orifice in the body configured to be closed by the clamp during its sliding contact parallel to the translational movement against said body of the device, said orifice being continued by an air supply channel.

[0026] The detection means make it possible to know the position of the flange by blocking the orifice, which varies the pressure in the air supply channel. A pressure sensor at the supply means of this channel thus makes it possible to detect a blockage of the orifice when the flange passes from the release position to the clamping position, and the flange is in a translational movement only. It is then possible to control the flow rate and the pressure of the fluid of the device cylinder to reduce it and carry out a fine adjustment of the tightening. Adjusting the position of the orifice along the body of the device makes it possible to define the moment of reduction of the fluid flow rate.

[0027] According to yet another feature of the invention, the clamping device comprises two flanges parallel to each other longitudinally and two respective jacks.

[0028] This allows for clamping on two nearby areas, and increases the clamping surface of the ends of the clamps on one surface of a part to be clamped. This is especially true if this surface is not parallel to the ends of the clamps.

[0029] According to an alternative or complementary embodiment of the invention, each flange of the clamping device comprises a beak having at its end a flat zone pivotally mounted on a ball joint.

[0030] This allows the contact of the nozzle of the flange(s) on the surface of the part to be made on a surface and not on a line or point.

[0031] Other aims and advantages of the present invention will appear during the description which follows with reference to the attached drawings illustrating an exemplary embodiment and in which: [ Fig.1 ] is a front perspective view of a clamping device having characteristics of a clamp and a cylinder known from the state of the art; [ Fig.2 ] is a rear perspective view of a clamping device of the figure 1 ; [ Fig.3 ] is a partial sectional view of the device illustrated in figures 1 et 2 but whose flange is in the released position, the cut being made along a plane parallel to the median plane of this device; [ Fig.4 ] is a sectional view of the device illustrated in figures 1 et 2 , carried out along the median plane of this device; [ Fig.5 ] is a front perspective view of a clamping device in the maximum clamping position according to the invention, said device comprising in particular the characteristics of the flange and the cylinder of the device of the figure 1 ; [ Fig.6 ] is a rear perspective view of the clamping device of the figure 5 ; [ Fig.7 ] is a sectional view of the device illustrated in figures 5 et 6 , carried out along the median plane of this device; [ Fig.8 ] is a front perspective view of the clamping device of the figure 5 when the flange is in an intermediate position between the release position and the clamping position, in the translation position only; [ Fig.9 ] is a rear perspective view of the clamping device of the figure 8 ; [ Fig.10 ] is a sectional view of the device illustrated in figures 8 And 9 , carried out along the median plane of this device; [ Fig.11 ] is a front perspective view of the clamping device of the figure 5 when the bridle is in the maximum release position; [ Fig.12 ] is a rear perspective view of the clamping device of the figure 11 ; [ Fig.13 ] is a sectional view of the device illustrated in figures 11 et 12 , carried out along the median plane of this device;

[0032] As represented in the figures 5 and following, the present invention relates to a clamping device D for clamping a part. This clamping device D comprises a jack 1 and a flange 2. The flange comprises a nose 20 oriented towards a so-called forward direction when the clamping device D is in the clamping position as illustrated in the figure 5 . The clamping device actually has a front and a rear defined by the beak 20. The left side of the figures 4 , 7 , 10 And 13 is considered forward-facing, and the right side is considered rear-facing.

[0033] The operation of the clamping device D with regard to the movement of the flange 2 under the action of the jack 1 has the characteristics described in the document EP1697088B1 and reproduced below. figures 1 à 4 correspond respectively to the figures 1 , 2 , 4 And 5said document EP1697088B1 and include a clamping device according to the prior art.

[0034] Thus, the cylinder 1 is a double-acting hydraulic cylinder and comprises a body 10 fixed in operation to the tool itself arranged for example in a machining center, and a rod 11 movable relative to the body 10 of this cylinder.

[0035] The body 10 of the jack has a bore inside which a piston 12, integral with the rod 11, delimits a first chamber 101 and a second chamber 102 of variable and complementary volumes, each of which can be connected to a high pressure hydraulic source while the other is connected to a low pressure reservoir.

[0036] The flange 2, which is articulated on the rod 11 around a pivot axis X, is driven at will by the rod 11, itself driven by the piston 12.

[0037] The flange 2 thus moves, over a determined stroke, between a tightening position illustrated in particular in figures 1 , 2 , 4 , and to the figures 5 à 7 , and a release position, illustrated in figures 3 And 11 à 13 .

[0038] Under these conditions, the flange 2 is driven from its release position to its clamping position by admission of pressurized fluid into the first chamber 101 of the cylinder 1, and is driven from its clamping position to its release position by admission of pressurized fluid into the second chamber 102 of this cylinder 1.

[0039] The device D comprises guide members 3 and support elements 4, the guide members 3 themselves comprising a guide member 31 fixed relative to the body 10 and a movable guide member 32 linked to the flange 2, and the support elements 4 comprising, in the same way, a support element 41 fixed relative to the body 10 and a movable support element 42 linked to the flange 2.

[0040] The fixed and mobile guide members, 31 and 32, cooperate to drive the flange 2 in a rotational movement around the pivot axis X at least at the end of the travel of this flange towards its release position, and to drive the flange 2 in a translational movement at least at the end of the travel of this flange towards its clamping position.

[0041] For their part, the fixed and mobile support elements, 41 and 42, cooperate, at least at the end of the travel of the flange 2 towards its clamping position, to offer each other, at a distance from the guide members 3, a sliding contact parallel to the translational movement of the flange 2 and allowing the flange 2 to brace itself on the part to be clamped.

[0042] Advantageously, the rod 11 preferably extends along a translation axis Z which passes between the guide members 3 and the support elements 4.

[0043] Here, the movable guide member 32 comprises a cam formed of two grooves, hollowed out symmetrically in the flange 2 on either side of a median plane M of the device, this median plane M being transverse to the pivot axis X and constituting a plane of symmetry for the flange 2 and for the rod 11. Each of the grooves has a path which continuously approaches the pivot axis X from the first end 321 of this path towards its second end 322. This path comprises a rectilinear path portion 320r which ends at the first end 321 and a curved path portion 320c, adjacent to the rectilinear path portion 320r and ending at the second end 322.

[0044] There figure 3 has only one cam, the other cam being deduced by symmetry with respect to plane M.

[0045] The fixed guide member 31 is constituted by a pair of pins or rollers, fixed to the body 10 of the jack 1 and respectively engaged in the grooves forming the cam. The body 10 comprises two pins or rollers 31, one visible on the figure 3 , the other being deduced by symmetry with respect to the plane M.

[0046] As shown in the figure 3 , each stud or roller 31 is located above a plane T which is transverse to the rod 11 and which contains the pivot axis X, when following a direction which corresponds to the movement carried out by the rod 11 to drive the flange 2 towards its release position.

[0047] The mobile support element 42 is constituted by a support heel which is carried by the flange 2 and which extends symmetrically on either side of the median plane M of the device.

[0048] The fixed support element 41 is constituted by an external support surface of the body 10 of the jack 1, on which the support heel 42 rests symmetrically with respect to this same median plane M.

[0049] In the embodiment of the invention illustrated here in the figures, the rod 11 comes out of the jack 1 from the side of its first chamber 101.

[0050] In this case, the fixed guide member 31 and the fixed support element 41 are advantageously carried by a part 100 of the body 10 of the jack which is shaped as a yoke, and the flange 2 is then guided in its median plane M between two parallel faces facing each other, 100a and 100b, belonging to this part 100 forming a yoke. This embodiment allows a significant rotation of the flange 2 between its clamping position and its release position, typically a rotation of amplitude equal to or greater than 90 degrees.

[0051] In addition to these elements described previously, the clamping device D comprises at least one covering cap 5, for example in the form of a plate having two ends 50, 51 and two lateral edges 52. The at least one covering cap 5 is placed between the two parallel faces 100a and 100b, belonging to the part 100 forming a yoke, and perpendicular to these faces.

[0052] The at least one covering hood 5 comprises a first end 50 in the direction of the flange 2. This first end 50 cooperates with this flange by a pivot connection called a pivot connection. To do this, the at least one covering hood 5 comprises two shafts carried by the same virtual axis of rotation parallel to the pivot axis X. These two shafts come from the first end 50 of the hood 5 and extend in opposite directions. These shafts cooperate by fitting into reciprocal bearings hollowed out in the flange 2. The bearings and the shafts form pivot connection means between the at least one hood 5 and the flange 2.

[0053] Of course, other embodiments of a pivot connection can be envisaged in the spirit of the invention.

[0054] The at least one covering hood 5 comprises a second end 51 opposite the first end 50. This second end 51 cooperates with the body 10 of the clamping device D by a sliding connection called a translation connection. In fact, the two parallel faces 100a and 100b, belonging to the part 100, comprise grooves forming slides in which the lateral edges 52 slide or slide. The slides and the edges form sliding connection means.

[0055] Of course, here too other embodiments of a pivot connection can be envisaged in the spirit of the invention.

[0056] The at least one covering hood 5 may also comprise an elastically deformable zone 53, in particular under the action of a force whose vector is parallel to the median plane M.

[0057] According to an embodiment of the invention illustrated in the figures 5 à 13 , the clamping device D comprises a front covering hood 5a on the front of the clamping device D as particularly illustrated in the figures 5 , 8 And 11 , and it comprises a rear covering hood 5b on the rear of the clamping device D as particularly illustrated in the figures 6 , 9 And 12 . The sectional views of the figures 7 , 10 And 13allow the front 5a and rear 5b cover covers to be illustrated at the same time in the same figures. These sectional views also allow the deformation zones 53 of the cover covers 5a, 5b to be clearly distinguished. As can then be seen in these figures, the elastically deformable part 53 of the front cover cover 5a is not deformed when the flange 2 is in the clamping position, and it is deformed when the flange 2 is in the release position. Conversely, the elastically deformable part 53 of the rear cover cover 5b is not deformed when the flange 2 is in the release position, and it is deformed when the flange 2 is in the clamping position. Thus the covers follow the complex movement of the flange 2 to protect the mechanisms of this clamping device D in a simple and compact manner.

[0058] Each covering hood 5a, 5b is preferably but optionally made of metallic material, in particular steel.

[0059] According to a particular embodiment of the invention, the fixed support element 41 of the clamping device D has on its surface against which the movable support element 42 of the clamp 2 slides an orifice 6. This orifice 6 is continued by an air supply channel. Air is blown through this channel and this orifice 6.

[0060] When the movable support element 42 closes the hole 6 by sliding against the fixed element 41 by translation, an increase in the pressure of the air blown into the then blocked orifice 6 can be detected. We then know that the flange 2 has finished its pivoting and that it enters its translation phase to come into contact with the part to be clamped and then come to brace itself against it. We can then reduce the flow rate of the fluid supplying the cylinder 1 of the clamping device D to finely adjust the descent of the flange 2 and the clamping force.

[0061] This provides, at low cost and simply, detection means for detecting when the flange is in translation only during the movement of the flange from the release position to the clamping position. These detection means include, among other things, the orifice 6.

[0062] A second orifice in the upper part of the body also connected to the channel advantageously prevents the air supply channel from being completely blocked.

[0063] According to a further particular embodiment of the invention not illustrated here, the clamping device comprises two flanges parallel to each other longitudinally in a front / rear direction. Each flange is controlled by a corresponding cylinder. Each flange may comprise a single roller or stud moving in a cam. The device may also comprise a central plate carried by the median plane M in which two cams are placed and in which rollers or studs attached to only one of the flanges 2 act independently.

[0064] According to another particular embodiment of the invention not illustrated here, the spout 20 of the flange 2 comprises a movable element in ball joint connection at its end configured to be inserted between the spout 20 and a part to be clamped. This movable element comprises on the one hand a ball joint which is fitted into a housing corresponding to the end of the spout 20, and on the other hand a flat zone configured to come opposite and into contact with a part to be clamped. Of course, this embodiment can be applied to the two flanges 2 of the embodiment of the device described in the previous paragraph.

[0065] This results in a compact, robust D-clamping device that is more resistant to environmental stresses. This improves its lifespan and reduces maintenance.

[0066] The adjustment of the descent of the flange 2 towards its clamping position can be done at suitable speeds and at low cost and by means not requiring significant maintenance.

[0067] In addition, this clamping device also ensures better support for the parts to be clamped and limits the creation of clamping marks on the part to be clamped.

Claims

1. Device (D) for clamping a part on a tool, comprising a jack (1) and a flange (2), the jack (1) being selectively actuated by a pressurized fluid and itself comprising a body (10) fixed in operation to the tool and a rod (11) movable relative to the body (11), and the flange (2) being articulated about a pivot axis (X) on the rod (11) and selectively driven by the rod (11), this flange (2) moving over a determined stroke between a clamping position and a release position, and undergoing rotation over at least part of its stroke, this clamping device (D) further comprising guide members (3) and support elements (4), these guide members (3) comprising a guide member fixed (31) relative to the body (10) and a movable guide member (32) linked to the flange (2),these fixed and mobile guide members cooperating to drive the flange (2) in a rotational movement around the pivot axis (X) at least at the end of its travel towards its release position and in a translational movement at least at the end of its travel towards its clamping position, and these support elements (4) comprising a fixed support element (41) relative to the body (10) and a mobile support element (42) linked to the flange (2), these fixed and mobile support elements cooperating selectively, at least at the end of the travel of the flange (2) towards its clamping position, to offer each other, at a distance from the guide members (3), a sliding contact parallel to the translational movement of the flange (2) and allowing the flange (2) to be buttressed on the part to be clamped, , characterized by the fact thatthe clamping device (D) comprises detection means configured to detect when the flange (2) is in translation only during the movement of the flange (2) from the release position to the clamping position, these detection means comprising an orifice (6) in the body (10) configured to be closed by the flange (2) during its sliding contact parallel to the translational movement against said body (2) of the clamping device (D), said orifice (6) being continued by an air supply channel.

2. Clamping device (D) according to claim 1, comprising a second orifice in the body (10) also connected to the air supply channel so as not to completely block the air supply channel when said orifice (6) is closed by the flange (2).

3. Clamping device (D) according to claim 1 or 2, wherein the orifice (6) is provided on a surface of the fixed support element (41) against which the movable support element (42) slides.

4. Clamping device (D) according to claim 1 to 3, comprising at least one covering hood (5, 5a, 5b) comprising two ends, a first end (50) cooperating with the flange (2) by a pivoting connection, a second end (51) cooperating with the body (10) by a translational connection.

5. Clamping device (D) according to claim 4, characterized by the fact that the first end (50) of the covering hood(s) (5, 5a, 5b) comprises two shafts originating from the hood (5, 5a, 5b) and extending laterally in opposite directions, these shafts cooperating by fitting into reciprocal bearings of the flange (2) to form pivoting connection means.

6. Clamping device (D) according to one of claims 4 or 5, characterized by the fact that the covering hood(s) (5, 5a, 5b) have lateral edges (52) configured to slide in facing slides of the body (10) to form translational connection means.

7. Clamping device (D) according to one of claims 4 to 6, characterized by the fact that the at least one covering hood (5, 5a, 5b) comprises an elastically deformable part (53).

8. Clamping device (D) according to claim 7, characterized by the fact that it comprises a covering hood (5a) whose elastically deformable part (53) has a configuration without deformation when the flange (2) is in the clamping position, and which has a deformed configuration when the flange (2) is in the releasing position.

9. Clamping device (D) according to claim 7 or claim 8, characterized by the fact thatit comprises a covering hood (5b) whose elastically deformable part (53) has a configuration without deformation when the flange (2) is in the clamping position, and which has a deformed configuration when the flange (2) is in the releasing position.

10. Clamping device (D) according to one of claims 4 to 9, characterized by the fact that it comprises two flanges (2) parallel to each other longitudinally and two respective jacks (1).

11. Clamping device (D) according to one of claims 4 to 10, characterized by the fact that the flange (2) of the clamping device (D) comprises a beak (20) having at its end a flat zone pivotally mounted on a ball joint.

12. Clamping device (D) according to one of claims 1 to 11, in which the cylinder (1) is a double-acting hydraulic cylinder.

13. Clamping system, comprising: - a clamping device according to one of claims 1 to 12, - means for supplying the air supply channel, - a pressure sensor arranged at the supply means.

14. Clamping method, comprising the steps of: - providing a clamping system according to claim 13, - controlling a movement of the clamp (2) from the release position to the clamping position, - detecting a blockage by the clamp (2) of said orifice (6) of the detection means, - reducing a supply flow rate of the jack (1).

Images