EP3972767A1

EP3972767A1 - Gripping clamp

Info

Publication number: EP3972767A1
Application number: EP20742309.6A
Authority: EP
Inventors: Vincent PINTER; Sylvain WILLAUME-LANG
Original assignee: DE STA CO France SAS
Current assignee: DE STA CO France SAS
Priority date: 2019-05-20
Filing date: 2020-05-18
Publication date: 2022-03-30
Also published as: FR3096285A1; WO2020234536A1; FR3096285B1

Abstract

A gripping clamp (200) comprises a casing (202) which defines, internally, the chamber (210) of a cylinder (216), this casing (202) comprising a lid (208) which closes access to the interior thereof, and gripping members (204), each subjected to a displacement with respect to the casing (202) under the effect of the cylinder (216). The casing (202) further comprises a metal sleeve (212) which forms the lateral wall (231) of the chamber (210) of the cylinder (216), and a body (206), at least partially made of composite material, which tightly surrounds the sleeve (212) so as to form a rigid assembly with the sleeve (212) and the lid (208).

Description

Title of the invention: Gripper The invention relates to a gripper, and more particularly a gripper of the type comprising a casing, which internally defines the chamber of a jack, the casing comprising a cover which closes access to its interior, and gripping members, jointly subjected to a displacement relative to the housing, under the effect of the jack. It is mainly a matter of moving these organs between a closed position, where the grippers are located close to each other, and an open position, where these organs are located far from each other.

Grippers may also be referred to in the art as "collets", or alternatively "clamps". The term "mandrel" is also encountered, for clamping or gripping, in particular in the case where the housing has a generally cylindrical appearance. In English, they are generally generically called "gripper" (literally "pincer" in French), or sometimes, more precisely, "pawerful gripper" ("gripper of power"). These grippers are widely used in industry to grip or hold workpieces, or assemblies of such parts, for example, to manipulate or move them. They may be heavy parts or, more generally, difficult to maintain, requiring a fairly large clamping force. Grippers of this type are appreciated for their compactness and versatility.

Despite a small footprint, these grippers are capable of a large clamping force and, if necessary, a long stroke. They offer a wide variety of grips, depending on the displacement of the gripping members, angular or linear, the number of these members, two or three, generally, and gripping members of different types for the same casing.

The gripping members generally comprise fingers, also called "jaws", each fixedly mounted on a respective jaw holder. The jaw holders are mounted to move relative to the housing, generally sliding or pivoting. The jack is generally of the hydraulic or pneumatic type.

These grippers are often used in a robotic environment.

Typically, a gripper is mounted at the end of a robotic arm, which must be able to be moved quickly and precisely.

We are more particularly interested here in clamps capable of exerting a sufficiently large clamping force to hold heavy parts or whose material, shape, state or conditions in which one operates, among other things, complicate the maintenance. Typically, this tightening force is greater than 500 newtons, and can go beyond 1300 newtons.

An effort of this order involves, on the one hand, a casing with high mechanical strength and, on the other hand, a cylinder capable of operating at high pressures, up to 6 or even 7 bars. The housing is generally made in one piece and made of metal, most often steel, in the form of a fairly massive part. The cylinder chamber is machined inside this part. For a clamping force of the type mentioned above, the housing generally has a size of the order of 100 millimeters in diameter, or even more. In addition, the clamps must have a sufficient life of the order of one million cycles.

Clamps of this type have a fairly large mass. The Applicant has identified drawbacks linked to the large mass of these clamps. It sought to reduce it, without compromising the mechanical performance or the reliability of the grippers. The Applicant has also endeavored to improve its manufacture. The invention thus improves the situation.

For these purposes, there is proposed a gripper of the type comprising a casing which internally defines the chamber of a cylinder, this casing comprising a cover which closes access to its interior, and gripping members, each subjected to a displacement relative to the housing under the effect of the jack.

The casing further comprises a metal jacket which forms the side wall of the chamber of the cylinder, and a body, at least partly made of composite material, which encloses the jacket so as to form a rigid assembly with the jacket and the cover.

This clamp can be moved more easily by a motorized arm, due to the lower mass and reduced inertia: the acceleration and braking of the motorized arm can be faster. This allows for higher work rates, compared to a conventional clamp.

In addition, the manufacture of this clamp, with a housing made at least partially of composite material, is easier and less expensive, in comparison with clamps whose housing is made of steel. A composite material is easier to conform. In particular, the body can be produced by additive manufacturing, which is also called three-dimensional printing or 3D printing.

In various variations, the clamp may have one or more of the following aspects:

the sleeve includes a base that forms the bottom of the cylinder chamber, at the front of the body,

the casing also includes a metal cap assembled in a sealed manner at the rear of the jacket, so as to delimit the cylinder chamber with the jacket,

the shirt is threaded into the body and the cover tightens the shirt against the body so as to form a rigid whole with them,

the cover is at least partly made of a composite material,

the housing comprises a cover at least partly made of composite material, integral with the body, said cover being in connection with the gripping members (204, the cover comprises a reinforcing part of composite material, arranged in the center of the cover,

the cap comprises a metal reinforcing ring, arranged on the periphery of the cap, the composite material comprises a material from the family of thermoplastic polymer composites, preferably nylon or nylon copolymer, the composite material further comprises poly (p-phenyleneterephthalamide), PPD-T, of the type known under the name of Kevlar , carbon fiber, fiberglass or high temperature high strength glass fiber or a combination thereof,

at least one part made of composite material comprises:

* a first portion, which forms an outer envelope of the part, in a material of the family of thermoplastic polymer composites, preferably nylon, nylon copolymer, or a combination thereof, and

* a second portion of long fibers, which forms a reinforcing structure for the part, inside the outer casing, the long fibers comprising fibers of Kevlar, carbon, glass, high-resistance high-temperature glass or a combination of these fibers,

the body, the cover or the cap are made by additive manufacturing, the jacket and / or the cap are in aluminum,

the clamp further comprises a transmission which transmits the movement of the cylinder to the grippers, in which the transmission comprises as many levers as there are grippers, each lever being pivotally mounted in the housing around a circumferential direction, and wherein the cylinder drives the levers, and each lever in turn drives its respective gripper, and the clamp further comprises a front port and a rear port, which supply fluid to the chamber, the front port and the port rear being provided in the body so as to open onto the walls of the chamber left free by the jacket and the cover.

A housing for a gripper is also proposed, of the type internally defining the chamber of a jack and comprising a cover which closes access to its interior. The casing comprises a metal jacket which forms the side wall of the chamber of the cylinder, and a body, at least partly made of a composite material, which encloses the jacket so as to form a rigid assembly with the jacket and the cover. A method of manufacturing a gripper of the type comprising a casing which internally defines the chamber of a cylinder, this casing comprising a cover which closes access to its interior, and gripping members, subjected each to a displacement relative to the casing under the effect of the jack. The casing further comprises a metal jacket which forms the side wall of the chamber of the cylinder, and a body, at least partly made of composite material, which encloses the jacket so as to form a rigid assembly with the jacket and the cover. The body is produced by additive manufacturing. Other characteristics and advantages of the invention will be explained in detail in the description below, made with reference to the appended drawings, in which:

[Fig. 1] is an axial sectional view of a conventional type gripper,

[Fig. 2] shows an axial sectional view of a gripper according to a first embodiment of the invention,

[Fig. 3] shows the clamp of Figure 2 in top view,

[Fig. 4] shows an alternative embodiment of the clamp of Figures 2 and 3, in top view,

[Fig. 5] is a perspective view of a cap for the clamp of Figures 2 and 3,

[Fig. 6] schematically shows the composite structure of the cap of Figure 5, in axial section,

[Fig. 7] shows a clamp according to a second embodiment of the invention, seen in axial section,

[Fig. 8] shows a clamp according to a third embodiment of the invention, viewed from above,

[Fig. 9] shows the clamp of Figure 8, sectional view along line IX-IX, [Fig. 10] shows the clamp of Figure 8, sectional view along line X-X, [Fig. 11] shows the clamp of Figure 8, sectional view along line XI-XI, [Fig. 12] shows a detail CP of figure 10,

[Fig. 13] shows a CIP detail of figure 11,

[Fig. 14] shows a clamp according to a variant of the third embodiment, seen in axial section, [Fig. 15] shows a perspective view of a sleeve for the clamp of figure 2, and

[Fig. 16] shows the liner of FIG. 15, viewed in axial section. The appended drawings essentially contain elements of a certain character that can therefore not only serve to make the present invention better understood, but also contribute to its definition, where appropriate.

FIG. 1 represents a conventional clamp 100, of known type.

The conventional clamp 100 comprises a casing 102 and gripping members 104 movably mounted on the casing 102, here three in number.

The housing 102 is shaped as a rigid envelope, which protects the constituent elements of the conventional clamp 100. The housing 102 comprises fixing means, for example threads, for fixing the conventional clamp 100, typically at the end of a robotic arm.

The housing 102 comprises a body 106 in the form of a single piece which extends between a first large face, or front face 107, and a second large face, or rear face 109, mutually opposed. Here, the body 106 has the general appearance of a straight cylinder with a central axis 113 and a lateral face 111.

The body 106 has a blind bore 101, open on the rear face 109 of the body 106 and which generally extends along the axis 113. Here, the bore 101 is shaped as a portion of a right cylinder. The bore 101 has a side wall 103, generally cylindrical, and a bottom 115, on which the side wall 103 rests. The bottom 115 corresponds to the part of the bore 101 close to the front face 107 of the body 106. The bottom 115 corresponds to the part of the bore 110 remote from the rear face 109 of the body 106.

The side wall 103 and the bottom 115 of the bore 101 jointly define the chamber 110 of a jack 112. The chamber 110 is formed in the body 106. The bottom 115 of the bore 101 produces the bottom of the chamber 110. Here, the bottom 115 is disc-shaped.

The housing 102 comprises a cover 108, which is fixed to the rear face 109 of the body 106 so as to close the chamber 110 of the cylinder 112. The cover 108 has the general shape of a disc with a first face, or front face 107-2. , and a second face, or rear face 109-2, mutually opposed. The front face 107-2 of the cover 108 is shaped in a complementary manner to the rear face 109 of the body 106. This front face 107-2 of the cover 108 is intended to come into contact with the rear face 109 of the body 106 when the body 106 and cover 108 are mutually assembled.

The side wall 103 and the bottom 115 of the bore 101 jointly define, with a central part of the front face 107-2 of the cover 108, the chamber 110 of the cylinder 112.

The piston 114 of the cylinder 112 is slidably mounted on the body 106, across the chamber 110. This sliding takes place along the central axis 113 of the body 106. The piston 114 has the general shape of a disc. The cylinder 112 further comprises a rod 116, integral with the piston 114. The rod 116 is generally cylindrical. One end of the rod 116 is fixed to the piston 114, for example by means of a screw 117.

The chamber 110 is fluid tight. The cylinder 112 can be hydraulic or pneumatic.

The body 106 comprises a second bore 119, which runs from the bottom 115 of the blind bore 101 to the front face 107 of this body 106. The second bore 119 extends in the direction of the central axis 113 of the body 106, here from coaxial with this axis 113. The second bore 119 has a cross section of shape complementary to that of the rod 116. The second bore 119 and the rod 114 have for example a generally circular cross section. The rod 116 is slidably received in the second bore 119. The rod 116 projects out of the chamber 110. The jack 112 is fitted with one or more seals which participate in the sealing of the chamber 110. The jack 112 comprises a first seal 140, arranged to provide a fluid seal between the second bore 119 and the rod 116. The first seal 140 is mounted around the rod 116. The first seal 140 is housed in an annular groove, formed in the second bore 119. The cylinder 112 comprises a second seal 142, arranged to provide a seal between the cover 108 and the body 106. The second seal 142 is housed in a circumferential groove, formed on the front face 107-2 of the cover 108. When the cover 108 is mounted on the body 106, the second seal 142 is compressed between the rear face 109 of the body 106 and the front face 107-2 of the cover 108.

The cylinder 112 further comprises a third seal 144, arranged to provide a seal between the piston 114 and the chamber 110. The piston 114 sealingly divides the chamber 110 into a first portion 146 and a second portion 148. The third seal 144. is housed in an annular groove, formed on the circumference of a lateral face 145 of the piston 114. The body 106 comprises two orifices, not shown, which each open into a respective one of the first portion 146 and the second portion 148 of the chamber 110. These orifices serve to supply these portions with fluid. These two orifices partly form at least part of the actuator 112 control means.

The gripping rods 104 are mounted on the body 106, each sliding in a respective direction, or direction of action 121. The directions of action 121 each have a non-zero radial component. Here, these directions of action 121 are located in a common plane, orthogonal to the central axis 113 of the body 106. These directions 121 are concurrent at a point of this axis 113. The point of intersection of the directions of action 121 could be offset from this axis 113.

The conventional clamp 100 further comprises a transmission 118, arranged between the rod 114 of the cylinder 112 and the members 104. The transmission 118 transforms a translational movement of the piston 114 relative to the body 106 in a combined movement of the members 104, along its respective direction of action 121. The members 104 can be moved between a first position, or open position, where these members 104 are distant from each other and a second position, or closed position, where these members 104 are located close to each other. This transformation is reversible, or bidirectional. The transmission 118 is housed in the body 106, between the bottom 115 of the terminal bore 101 and the front face 107 of the body 106. The transmission 118 here comprises a respective lever 120 for driving each gripping member 104. Each lever 120 is mounted to pivot on the body 106, here via a respective axis 122. The axis 122 of each lever 120 is mounted on the body 106, in a circumferential direction of this body 106. This circumferential direction is a direction orthogonal to both the axial direction and the radial direction of the body 106.

Each lever 120 has a first end portion 124 in engagement with the rod 114 and a second end portion 126 in engagement with a respective member 104. Here, the first end portion 124 of each lever 120 is housed in a common annular groove 128, formed in the vicinity of an end 130 of the rod 116 opposite to the piston 114. The second end portion 126 of each lever 120 is housed in a groove 132 formed on a rear face 134 of a respective member 104.

The housing 102 includes a plurality of recesses 136, which each house a respective lever 120. Each recess 136 is open on a respective groove 132. The second end 126 of each lever 120 projects from a respective recess 136 into the corresponding groove 132.

Each recess 136 extends generally radially.

The recesses 136 are open on the lateral face 111 of the body 106. The levers 120 can thus be accessed from this lateral face 111, for their assembly and their maintenance. Each recess 136 is closed by a respective cover 138, removably mounted on the body 106. The covers 138 protect the transmission 118, for example from projections of lubricant or of chips. The members 104 shown here take the form of jaw holders, which here each protrude from the front face 107 of the body 106. In practice, each member 104 further comprises a respective jaw, not shown, fixed to the jaw holder by one or several journals 150. The body 106 comprises grooves 123, one per member 104, which each extend in a respective direction of action 121. Each groove 123 has a profile corresponding in shape to a respective jaw holder. Each groove 123 houses a respective jaw-holder sliding in a longitudinal direction of this groove 123. Each groove 123 is arranged with a respective jaw-holder in a sliding connection in the respective direction of action 121 of a member 104.

The cylinder 112 is designed to operate with high fluid pressures, on the order of 6 or even 7, bars. Such pressures allow the conventional clamp 100 to develop forces of the order of 1000 to 1300 newtons in the members 104. The walls of the chamber 110, including the sealed assembly of the cover 108 on the body 106, are capable of withstanding such pressures, while ensuring good guidance of the piston 114, over a long lifetime.

The body 106 and the cover 108 of the conventional clamp 100 are made of metal, preferably steel. The chamber 110 is machined inside the body 106. The side walls of the chamber 110 are sometimes rectified in order to obtain a surface condition suitable for the operation of the jack 112. The same can be said of the recesses 136, the grooves. 123 and the second bore 119. The body 106 is quite heavy and complex to manufacture.

B is now referred to Figures 2 and 3.

They show a different type of gripper, or improved gripper 200. Like the conventional gripper 100, the improved gripper 200 comprises a housing 202 and grippers 204 movably mounted on the housing 202. By way of example, the improved gripper 200 here comprises three grippers 204.

The housing 202 comprises a body 206 produced in the form of a single piece, which extends between a first large face, or front face 203, and a second large face, or rear face 205, mutually opposed. Here, the body 206 has the general appearance of a straight cylinder, with a central axis 217 and a lateral face 211. This lateral face 211 extends from the front face 203 to the rear face 205 of the body 206. The front face 203 of the body 206. body 206 corresponds to the front of the improved clamp 200, while the rear face 205 of the body 206 corresponds to the rear of this improved clamp 200. The body 206 has a first recess 213, open on the rear face 205 of the body 206, and which generally extends along the central axis 217 of this body 206. Here, the first recess 213 is shaped as a portion of a right cylinder.

The recess 213 has a generally cylindrical side wall 201, and a bottom 215 on which the side wall 201 rests. The bottom 215 corresponds to the part of the recess 213 close to the front face 203 of the body 206. The bottom 215 corresponds to the part of the first recess 213 remote from the rear face 205 of the body 206.

Here, the bottom 215 is disc-shaped, and extends in a plane orthogonal to the central axis 217 of the body 206. The bottom 215 and the side wall 201 of the first recess 213 together define a housing an arrangement of parts forming the chamber. 210 of a jack 216.

The casing 202 further comprises a cover 208, which is fixed to the rear face 205 of the body 206 so as to close the recess 213. The cover 208 has the general shape of a disc, with a first face, or front face 207, and a second face, or bitter face 209, mutually opposed. The front face 207 of the cover 208 is shaped here in a complementary manner to the rear face 205 of the body 206. This front face 207 of the cover 208 is intended to come into contact with the rear face 205 of the body 206 when the body 206 and the cover 208 are mutually assembled. The front face 207 of the cover 208 also contributes to delimiting the housing for the parts forming the chamber 210 of the cylinder 216. The casing 202 comprises a jacket 212, which is housed in the recess 213. The jacket 212 internally delimits the chamber 210 d. 'a jack 216. The casing 202 further comprises a cap 214, which is mounted on the sleeve 212 so as to close the chamber 210. The sleeve 212 and the cap 214 are here both generally axisymmetric in shape. The sleeve 212 and the cap 214 mount in the body 206 coaxially with the central axis 217 of the body 206. The sleeve 212 has a generally cylindrical side portion 243, of annular section, and a base portion 245, substantially planar. , to which the lateral part 243 is connected. The sleeve 212 is generally shaped as a portion of a straight cylinder, in which a blind hole 229 is made. The blind hole 229 is open on a rear face of the liner 212, opposite the base part 245. The blind hole 229 corresponds to the chamber 210.

The cap 214 is mounted on the sleeve 212 so as to close the blind hole 229. The sleeve 212 is installed in the housing 213 until it comes into abutment against the bottom 215 of the housing 213, here via its portion. base 245. The cover

208 attaches to body 206, behind liner 212 and cap 214. Body 206 and cover 208 jointly enclose liner 212 and cap 214 so as to form a rigid assembly with them. Cover 208 closes access to liner 212 and cap 214.

Cover 208 can be attached to body 206 via a plurality of bolts (not shown). Here, fixing holes 266 are formed on the periphery of the body 206 and of the cover 208 for the passage of such fasteners, threaded rods for example. These fasteners tighten the cover 208 against the body 206.

The sleeve 212 has a cross section of shape corresponding externally to the inside of the cross section of the recess 213. For example, the sleeve 212 has a cylindrical outer side face 237, a substantially planar front face 239, and a rear face. annular 241. Here, the hole blind 229 has a generally cylindrical side wall, of circular section, which forms an internal side wall 231 of the sleeve 212, and a disc-shaped front wall which forms a bottom 219 of the sleeve 212. The outer side face 237 and the inner side wall 231 of the sleeve 212 delimits the lateral part 243 of the sleeve 212. The front face 239 and the bottom 219 jointly define the base 245 of the sleeve 212.

The cap 214 is generally disc-shaped, with a generally cylindrical side face 224, which interconnects a front face 233 and a rear face 235 opposite to each other. Here, the outer side face 237 of the sleeve 212 is in surface contact with the side wall 201 of the first recess 213 of the body 206. Here, the front face 239 of the sleeve 212 abuts against the bottom 215 of the first recess 213 of the body 206. The internal side wall 231 of the sleeve 212, the front face 233 of the cap 214 and the bottom 219 of the sleeve 212 together delimit the chamber 210 of the jack 216.

When the cover 208 is mounted on the body 206, the front face 207 of the cover 208 comes into contact with the rear face 241 of the sleeve 212. The lid 208 presses the sleeve 212 against the bottom 215 of the body 206.

Here, the cap 214 is mounted inside the liner 212, in an axial portion thereof close to the rear face of this liner 212. Here, the inner side wall 231 of the liner 212 has a portion forming a radial shoulder, arranged so that the front face of the cap 214 abuts against this shoulder, while the outer side face 224 of the cap 214 bears against the side wall 231 of the blind hole 229.

The cap 214 can be fitted in the blind hole 229 in a snug fashion. This adjustment can be of the tight type. Hat 214 is here held against

the shoulder 237 by an elastic ring 264, or circlip. Here, the circlip 264 is disposed in a circular groove formed in the side wall 231 of the blind hole 229, at the rear of the cap 214. The shirt 212 and the cap 214 each have a substantially constant thickness. The thickness of the sleeve 212 and that of the cap 214 are substantially equal. The thickness of the jacket 212 and that of the cap 214 could be different.

The cylinder 216 can be hydraulic or pneumatic.

The piston 218 of the cylinder 216 is slidably mounted on the sleeve 212, across the chamber 210. The piston 218 is generally in the form of a disc. The jack 216 further comprises a rod 220, generally cylindrical, integral with the piston 218.

The body 206 further comprises a through orifice 221 along its central axis 217, which runs from the bottom 215 of the first recess 213 to the front face 203 of the body 206. The sleeve 212 comprises a bore 223 which passes through the bottom 219 of the sleeve. 212. When the sleeve 212 is mounted in the recess 213, the through hole

221 of the body 206 and the bore 223 of the sleeve 212 are located opposite each other. They jointly form a through hole, from the bottom 219 of the chamber 210 to the front face 205 of the body 206. Here, when the sleeve 212 is mounted in the body 206, the bore 223 of the sleeve

212 is coaxial with the central axis 217 of the body 206. The rod 220 is slidably received in the through hole 221 of the body 206 and in the bore 223 of the sleeve 212. The rod 220 is guided in translation by the bore 223 of the sleeve 212. The rod 220 projects out of the chamber 210 and the housing 213.

The through hole 221 of the body 206 and of the bore 223 of the sleeve 212 have cross sections complementary to that of the rod 220. Here, the rod 220, the bore 223 of the sleeve 212 and the through hole 221 of the body 206 each have a circular cross section. Bore 223 of sleeve 212 assists in guiding the assembly formed of piston 218 and rod 220. Through hole 221 may optionally assist in guiding piston 218 and rod 220 on body 206. Here, the piston 218 bears on its front face on the rod 220, and on its rear face on a shoulder portion of a tail 222 of the jack 216. This tail 222 is elongated. The tail 222 passes through the cover 208 to protrude from the housing 202. The tail 222, the rod 220 and the piston 218 together form a rigid assembly.

Here, the tail 222 is generally cylindrical. It is provided with a thread in the vicinity of its front end, which cooperates with an internal thread formed in the rod 220. The shank 222 clamps the piston 218 against the rod 220. The jack shank 222 passes through a first bore 225, formed in the cap 214, and a second bore 227, formed in the cover 208. The first bore 225 and the second bore 227 are coaxial with the central axis 217 of the body 206, when the cap 214 and the cover 208 are assembled to the body 206 .

A journal 226 is mounted here between the piston 218 and the rod 220 so as to prevent the rotation of the piston 218 relative to the rod 220.

Alternatively, shank 222 may be attached to rod 220 via a stud. Tail 222 is optional. The rod 220 can be fixed to the piston 218, for example by a screw. Alternatively, the rod 220 and the piston 218 can be made in one piece, with or without a tail 222.

The ram tail 222 allows the position of the piston or grippers 204 to be controlled from behind the improved gripper 200. The chamber 210 is sealed. The jack 216 is fitted with one or more seals which participate in the sealing of this chamber 210. The jack 216 comprises a first seal 246, here of the O-ring type, which provides a seal between the rod 220 and the sleeve 212. Here, this first seal 246 is arranged in a groove

circumferential, formed in the sleeve 212, on the side surface of the bore 223. The first seal 246 surrounds the rod 220. The first seal 246 helps to seal the chamber 210, including as the rod 220 slides through the bore 223.

Here, the jack 216 comprises a second seal 248, which provides a seal between the sleeve 212 and the cap 214. The second seal 248 is here of the O-ring type. The second seal 248 is disposed in an annular groove, formed on the outer side face 224 of the cap 214. The second seal 248 is compressed against the side wall 231 of the sleeve 212, when the cap 214 is mounted on the sleeve 212. The second seal 248 is compressed against the side wall 231 of the sleeve 212, when the cap 214 is mounted on the sleeve 212. The second seal 248 is compressed against the side wall 231 of the sleeve 212. second seal 248 participates in the sealing of the assembly of the sleeve 212 and the cap 214.

Here, the jack 216 comprises a third seal 250 which provides a seal between the tail 222 and the cap 214. Here, the third seal 250 is of the O-ring type. The third seal 250 is disposed in an annular groove formed in the side face of the bore 225 of the cap 214. The third seal 250 surrounds the tail 222. The third seal 250 contributes to the sealing of the chamber 210, when the tail 222 slides through bore 225.

The jacket 212 and the cap 214 jointly define a sealed chamber 210 by virtue of the first j anointed 246, second j anointed 248 and third j anointed 250. The body 206 or the cover 208 do not contribute in any way to the sealing of this chamber 210.

The body 206 is made of a composite material. Here, the cover 208 is also made of a composite material. Alternatively, the cover 208 can be metallic. The sleeve 212 and the cap 214 are metallic, preferably aluminum.

As with the conventional clamp 100, the body 206 of the improved clamp 200 constitutes the bulk of the material volume of the casing 202. The fact that the body 206 is made of a composite material considerably reduces the weight of the casing 202 compared to a metallic body. , like the body 106 of the classic clamp 100.

The body 206 can be produced by additive manufacturing, a technique also known under the term "3D printing" (printing in three dimensions). This simplifies the manufacture of the body 206 of the improved clamp 200, as compared to that of the body 106 of the conventional clamp 100. This manufacture is more economical.

As the jacket 212 and the cap 214 are metallic, the walls of the chamber 210 of the jack 216 exhibit sealing, surface finish and mechanical strength which are comparable to those of the chamber 110 of the conventional clamp 100. It could be otherwise if these walls were made of a composite material, in particular directly on the body 206. The walls 231, 219 and 233 of this chamber 210 can be machined, in particular ground, in the sleeve 212 and the cap 214.

The sleeve 212 and the cap 214 are less bulky than the body 206. The casing 202 can be made with little metal. For example, cap 214 and liner 212 have a radial thickness 2.5 to 3 times less than the radial thickness of body 206.

The housing 202 of the improved gripper 200 is lighter and more economical to manufacture than the housing 102 of the conventional gripper 100. The improved gripper 200 has a particular configuration, with a body 206 of composite material and a sleeve 212 and a cap 214 metallic added inside this body 206. This configuration is advantageous in several respects.

- The jacket 212 and the cap 214 together produce a sealed chamber 210, with walls having a good surface condition, and which can withstand high operating pressures, compatible with the forces and pressures of the conventional clamp 100.

- The body 206 of composite material and the cover 208 make it possible to maintain satisfactory mechanical strength of the casing 202, comparable to the body 106 of the conventional clamp 100.

- The housing 202 is lighter and less expensive to manufacture than the housing 102 of the conventional clamp 100.

- Having a metal sleeve 212 and a cap 214 allows the improved clamp 200 to be much stronger and more efficient than a full plastic casing clamp.

The cylinder 216 comprises a fourth seal 252 arranged to provide a seal between the piston 218 and the side wall 231 of the chamber 210. The fourth seal 252 is disposed in a circumferential groove formed on the lateral face of the piston. 218. The fourth seal 252 is compressed between the piston 218 and the side wall 231. The piston 218 achieves, using the fourth seal 252, a sealed partition of the chamber 210 into a first portion 254 and a second portion 256. The chamber 210 comprises two orifices 312 and 314, each supplying one of the first portion 254 and the second portion 256 of the chamber 210 with fluid. The orifices 312 and 314 partly form means for controlling the actuator 216.

The housing 202 also includes a cap 268, produced in the form of a single piece. The cap 268 houses, at least in part, the grippers 204. The cap 268 extends between a front face 300 and a rear face 269, mutually opposed. Here, the cover 268 has the general appearance of a straight cylinder, with a side face 310. This side face 310 is shaped substantially in the same way as the side face 211 of the body 206. The cover 268 is fixedly mounted at the front of the body. body 206. The rear face 271 of the cover 268 is here conformed in a complementary manner to the front face 203 of the body 206 This rear face 271 is in contact with the front face 203 of the body 206, when the body 206 and the cover 268 are mutually assembled. Here, the cap 268 is held on the body 206 by a plurality of screws 270, received in blind threaded holes. As a variant, the cap 268 forms a single piece with the body 206.

The grippers 204 are mounted on the cover 268, each sliding in a respective direction, or direction of action 302. The directions of action 302 each have a non-zero radial component. Here, these three directions of action 302 are located in a common plane, orthogonal to the central axis 217 of the body 206. These directions of action 302 are concurrent at a point 304 of this central axis 217. The intersection point 304 of these directions of action 302 could be off-center from this central axis 217.

Each gripping member 204 comprises a jaw holder 258, provided with means for fixing a jaw (not shown) therein. Here, these means may for example comprise a plurality of holes 260, tapped or not, serving to place a jaw on the jaw holder 258, via studs, screws, journals or other suitable means for fixing two parts to each other.

Here, the cap 268 includes a respective groove 272 for each gripping member 204, formed along the respective direction of action 302. Each groove houses a respective jaw holder 258.

The front face 300 of the cap 268 is substantially disc-shaped. This front face 300 leaves the gripping members 204 visible. Here, each member 204 is slidably mounted, in a respective groove 272, along it.

In another embodiment, the improved gripper 200 may include more than three grippers 204. The grippers 204 are arranged such that their gripping directions are distributed evenly, angularly.

Here, the cap 268 is mostly made of composite material, which greatly reduces its weight compared to a cap that would be made of metal. The cap 268 could be made at least in part with metal.

The cap 268 comprises a solid central portion 306, which serves to reinforce the cap 268. This reinforcement increases the mechanical strength of the cap 268, compared to a cap 268 where the three grooves 272 meet in a recessed central portion, as this is the case for example in the conventional clamp 100. Although optional, this solid central portion 306 makes it possible to give the cap 268 a mechanical strength comparable to that of a metal cap or, at the very least, a resistance. sufficient for the forces envisaged, of the order of 100 to 40,000 Newtons. The cap 268 may further include a reinforcing ring 308. The reinforcing ring 308 can be embedded in the cap 268, or fixed to its surface. This reinforcing ring 308 (not visible in FIG. 3) is made of metal, preferably aluminum. The reinforcing ring 308 is preferably disposed at the periphery of the cap 268. The reinforcing ring 308 further increases the mechanical strength of the cap 268. The reinforcing ring 308 can be flat. The reinforcing ring 308 can be arranged on the side face 310 or on the front face 300 of the cap 268.

Alternatively, the reinforcing ring 308 can be disposed in the cap 268. To do this, the following steps are carried out when designing the cap 268 by additive manufacturing:

an annular housing is formed in the cap 268 during the early stages of additive manufacturing, then

additive manufacturing is discontinued, then

the reinforcement ring 308 is mounted in this annular housing, then additive manufacturing resumes until the design of the cap 268 is completed.

The improved gripper 200 further comprises a transmission 228 similar to the transmission of the conventional gripper 100, arranged between the rod 220 of the jack 216 and the grippers 204. The transmission 228 transforms a translational movement of the piston 218 relative to the body 206 in a combined movement of the grippers 204 each along its respective direction of action 302. The fairing 268, when mounted in front of the body 206, at least partially prohibits access to the transmission 228 from the outside. Here this

transformation is reversible, or bidirectional. Transmission 228 is housed here in front of jacket 212.

The transmission 228 here comprises a respective lever 230 for driving each gripping member 204. Each lever 230 is pivotally mounted on the sleeve 212, here around a respective axis 232. Each pin 232 is mounted on the sleeve 212 , in a circumferential direction thereof.

Each respective lever 230 includes a first end portion 234, engaged with the rod 220, and a second end portion 236, engaged with the gripper 204. Here, the first end portion 234 of each lever 230 is housed in a common annular groove 238, formed circumferentially in the vicinity of a front end 240 of the rod 220 opposite the piston 218. The second end portion 236 of each lever 230 is housed in a groove 242, formed on a rear face 234 of a respective gripping member 204. The composite material used includes a base material, also called printing material. The base material may comprise a member of the family of thermoplastic polymer composites, in particular nylon or nylon copolymer. In its tests, the Applicant used on the one hand nylon nylon and on the other hand the nylon copolymer Onyx, from the American company

MarkForged, Inc. The Applicant has also produced a prototype using the Duraform ProX HST polymer, sold by the company 3D Systems, Inc. The composite material can also optionally comprise a reinforcing material. The backing material can include one of the following: poly (p-phenyleneterephthalamide), or PPD-T, otherwise known as Kevlar, for example of the type known as CFF Kevlar Filament from the company MarkForged, Inc,

carbon fiber, in particular the CFF Carbon Fiber Filament product from MarkForged, Inc,

fiberglass, in particular the CFF Fiberglass Filament product from MarkForged, Inc,

high-strength, high-temperature fiberglass, in particular the CFF HSHT Fiberglass Filament product from MarkForged,

or a combination of these.

The reinforcing material increases the resistance of the base material, following the creation of fibers in the heart of the latter, as will be seen below.

The thermoplastic polymer composite (s) can be replaced at least in part by resin. This resin can be shaped by additive manufacturing. As a variant, the material of the body 206, of the cover 208 or of the cap 268 can comprise at least in part metal shaped by additive manufacturing, in particular the products H13 Tool Steel and / or 17-4 Stainless Steel from the company

MarkForged, Inc. Alternatively, body 206, cover 208, and cap 268 can be made from different materials. The Applicant has produced a first prototype made with the Duraform ProX HST polymer, in the form of a powder formed by laser fusion. The mass of this first prototype of improved gripper 200 is approximately 1.68 kg, against 2.575 kg for an equivalent gripping gripper 100 entirely made of aluminum. This first prototype achieves an actuation time of 10 ms, similar to that of the conventional clamp 100. Thus, this prototype makes it possible to reduce the weight of the clamp by approximately 35% while maintaining equivalent performance.

The Applicant has produced a second and a third prototype in Onyx nylon copolymer, shaped by depositing yarn. The mass of these second and third improved gripper prototypes 200 is approximately 1.93 kg. These prototypes have a mass approximately 25% less than the mass of a conventional homologous forceps. These second and third prototypes achieve an actuation time of 10 ms, similar to that of the classic clamp 100.

Thus, the improved gripper 200 is both lighter and easier to manufacture, while retaining performance equivalent to the conventional gripper 100, in terms of forces and actuation speed. Figure 4 shows a variant of the improved gripper 200 comprising only two grippers 204. These two grippers 204 have the same direction of action 402, and relative directions with respect to the housing 202 opposite. Thus, the grippers 204 move closer to each other and move away symmetrically.

Reference is made to Figure 5.

The cap 268 has on its rear face 269 a recess 307, to achieve a centering of the cap 268 on the body 206.

Reference is made to figure 6.

The cap 268 has a composite structure 600, which includes several portions: a first portion of base material, which corresponds to an envelope outer 602 of the cap 268,

a second portion of reinforcing material, which forms a reinforcing structure 604 of the cover 268, inside the outer shell 602, and

a third portion of base material shaped as a regular hollow network, which forms an internal filling 606 (in English "infill") of the cap 268, inside the reinforcement structure 604, and

a fourth portion of base material, which forms an internal support 608, inside the second portion 604. This composite structure 600 allows the cap 268 to have satisfactory strength and durability thanks to the interior long fibers, while by being easy to conform thanks to the walls in thermoplastic polymer composite.

The first portion 602, the third portion 606 and the fourth portion 608 can be made of materials different from each other.

The fibers of the reinforcing material of the second portion 604 are long fibers, here arranged along closed concentric lines, in the axial plane. Alternatively, the long fibers can be deposited isotropically, with

optionally a thermoplastic polymer composite between the fibers. The isotropic arrangement of fibers is advantageous for small grippers. The long fibers of the second portion 604 give the composite structure 600 great mechanical strength, taking into account the total weight of the cap 268.

The third portion 606 has a regular network structure with a hollow triangular mesh. This triangular mesh network structure is produced during the manufacture of the composite structure 600 by additive manufacturing. As a variant, the hollow mesh of this regular network can be hexagonal (nest structure

bee), rectangular, square, or any other mesh allowing a regular mesh.

The internal filling 606 allows the innermost parts of the reinforcing structure 604 to be filled. If long fibers were deposited instead of the filling internal 606 analogously to the second portion 604, they would have a strong curvature because of the lack of space. This would reduce the strength that these innermost fibers would provide to the composite structure 600. Further, such a full internal fill of long fibers would have a greater weight than the internal fill 606 in regular network of base material.

As a variant, the composite structure 600 may be devoid of internal filling 606 in a regular network. The fourth portion 608 provides a support for the manufacture of the composite structure 600 inside it. In particular, the fourth portion 608 supports the long fibers of the reinforcement structure 604, allowing the long fibers to be wound around the internal support as they are deposited. As a variant, the composite structure 600 may be devoid of a fourth portion 608 forming an internal support.

The body 206 and the cover 208, or one of the two only, may have a composite structure similar to the composite structure 600 described for the cap 268. In another embodiment, the body 206 and the cover 208 comprise material. base, without the addition of reinforcing material.

The composite structure 600 of the cover 268, the body 206 and / or the cover 208 improves the strength of these parts.

Reference is made to figure 7.

It shows an alternative clamp of the improved clamp 200, or second clamp 700. In this variant, the housing of the second clamp 700 does not have a cap 214. The sleeve 212 and the cover 208 are here assembled in a sealed manner. The walls of the chamber 210 of the jack are here produced by the cover 208 and the sleeve 212. The second clamp 700 comprises a transmission 701 with nut 702. The nut 702 is here secured to the rod 220 of the jack 216. This nut 702 comprises a projection 704 by respective member 204. The respective protrusion 704 engages with a respective groove 706 formed in the respective gripper 204. When moving the rod 220, the respective projection 704 of the nut 702 drives the respective gripping member 204.

Here, the nut 702 and the rod 220 are in one piece. Alternatively, the nut 702 and the rod 220 are secured to each other, for example by means of screws.

The projections 704 each have a side face oriented at an angle α, or transmission angle 708, with respect to the central axis 217 of the body 206. This transmission angle α defines the reduction ratio of the transmission 701. Here, the transmission angle 708 is 45 °, which corresponds to a reduction ratio of 1: 1.

The use of a 702 nut makes it possible to achieve high reduction ratios, in a smaller footprint than a lever transmission, such as that described in relation to figure 1.

Reference is made to FIGS. 8 to 13, which represent a second embodiment of a clamp according to the invention, or third clamp 800.

The casing 202 of the third clamp 800 comprises a simplified sleeve 812 and two gripping members 204. The gripping members 204 are mounted in the body 206 of the third gripper 800 to pivot, thus being able to achieve an angular gripping.

The simplified sleeve 812 of the third clamp 800 differs from the sleeve 212 of the improved clamp 200 in that it lacks a base portion 245 and a bottom 219. The manufacture of the simplified sleeve 812 of the third clamp 800 is simplified. . This simplified jacket 812 covers the recess 213 of the body 206 of the third clamp 800, which improves the surface finish, strength and durability of the side wall 201 of the chamber 210. The cover 208 is mounted after the simplified sleeve 812 on the body 206, so as to close the chamber 210. The simplified sleeve 812 is blocked in translation by the cover 208, which presses the simplified sleeve 812 against the bottom of the liner. 'recess 213 of the body 206.

The jack 216 comprises a front orifice 892 and a rear orifice 894 each supplying the front 246 and rear 248 portions of the chamber 210 respectively with fluid. Here, these front 892 and rear 894 orifices are formed in the body 206 and open outwardly on the side face 211 of the body 206. The front orifice 892 opens out on the front portion 846 of the chamber, here on the bottom 215 of the chamber. recess 213 of the body 206, at the front of the chamber 210. The rear opening 894 opens here on the side wall 201 of this recess 213, at the rear of the simplified sleeve 812.

The front 892 and rear 894 orifices open directly into the walls of the chamber left free by the simplified sleeve 812 and the cover 208. The front 892 and rear 894 orifices do not pass through the cover 208, nor through the simplified sleeve 812. This makes it possible to avoid the machining of these holes in the cover 208 or the simplified sleeve 812. In addition, the assembly of the simplified sleeve 812 and of the cover 208 is thereby simplified, since there is no in matching the orifices 892 and 894 formed in the body 206 with those formed in the cover 208 or the simplified sleeve 812. The manufacture of the parts of the third clamp 800 and their mutual assembly is thereby simplified.

Here, the simplified jacket 812 is here crenellated on its rear face, so as to allow the side wall of the chamber to remain partially free, while being able to be gripped by the cover 208.

Each gripping member 204 is here pivotally mounted in the body 206, around a respective circumferential direction. Each gripper 204 is mounted on a respective member pin 832. Each member 204 is housed in a respective radial groove 872 formed in the body 206.

The rod 220 of the cylinder 216 engages with each gripping member 204 at its front end 221. This rod 220 transmits the movement of the piston 218 to the respective grippers 204. Here, the rod 220 has in the vicinity of its front end 240 an annular rib 876 and an annular groove 877, in engagement with a radial groove 878 and one and a radial rib 879, formed in the respective gripping member 204. Here, the annular groove 877 is formed in the rod 220, at a distance from its front end 240, so as to form the annular rib 876 on the rod 220 without any additional operation.

When the piston 218 and the rod 220 slide relative to the casing 202 of the third clamp 800, the rod 220 drives the gripping members 204 into engagement, pivoting about their respective axis 832.

In one embodiment, the front orifice 892 opens outwardly at the level of the simplified sleeve 812 axially. To bypass the simplified jacket 812 and access chamber 210, the fluid supply port includes:

a first straight section 8920 which extends radially from the outer face 211 of the body 206 towards the interior of the body 206, to an inner end 8921 at a certain radial distance from the simplified liner 812, then following it

a bend 8922 which bypasses the liner from the front and leads to the bottom 215 of chamber 210.

Here turn 8922 has a right outer channel 8924 and a right inner channel 8926, connected by an 8928 bend at an acute angle, here approximately 45 °. The outer channel starts from the inner end 8921 of the first straight section radially inwardly and forwards to the elbow located more radially inward than the simplified liner 812. The inner channel starts from the elbow towards the front. 'rear, axially, up to the bottom 215 of the chamber 210.

Alternatively, the front port 892 goes from the side face 211 of the body 206 to the front of the simplified liner 812 to the bottom 215 of the chamber 210, without bypassing the simplified liner 812.

Reference is made to FIG. 14, which represents a variant of the third clamp 800, or fourth clamp 1400. The fourth clamp 1400 includes:

a bottomless 1412 liner, like the third clamp 800, and

a nut drive 1428, such as the second clamp 700. Reference is made to Figures 15 and 16, which show the sleeve 212 of the improved clamp 200.

The sleeve 212 has three respective housings 2120 projecting from the front face 239 of the sleeve 212, to accommodate the three axes 323 of the transmission 228.

Here, each housing 2120 is in the form of two elongated portions 2122 and 2124 parallel to each other. A respective bore 2126 and 2128 is provided in each elongated portion 2122 and 2124. The bores 2126 and 2128 are coaxial, and are shaped to accommodate the respective axis 232 of the transmission 228.

The two orifices 312 and 314 supplying the chamber 210 of the actuator 216 are here partly provided in the sleeve 212. The invention relates to a clamp with a lighter casing, thanks to the use of composite materials to produce the largest parts of the cylinder. crankcase. In particular, the invention relates to a one-piece body having a composite structure and a recess housing the chamber of a cylinder. In order to maintain satisfactory mechanical properties for this body, the recess is lined with a metal jacket. The sleeve delimits the side wall of the cylinder chamber.

This jacket can also help to define the bottom of the cylinder chamber. The invention also relates to a cap which can be assembled in a sealed manner with a bottom liner, so as to provide a sealed cylinder chamber with metal walls. The chamber thus retains a strong side wall adapted to the sliding of a piston, a seal sufficient for the pressures used and a relevant durability. In addition, the manufacture of this clamp is simplified, since it requires less metal, and less machining and grinding operations. The invention is not limited to the embodiments described. It can in particular be applied to other versions of the clamp. Thus, the invention relates to all grippers comprising the variants having:

2 to 6 jaw holders and more,

a nut or lever transmission,

direct transmission via the rod, or with intermediate elements between the rod and the gripping rods,

jaw holders in slide connection (“linear” gripper) or in pivot connection (“angular” gripper),

a body and a cap in one piece, or in two parts,

a cover, a body or a cover with a reinforcing ring as a metal core,

a simple shirt, without bottom, or a shirt with a base forming the bottom, a casing without a cap, or with a cap,

a sleeve housing the transmission, or without this function.

Claims

[Claim 1] Gripper (200, 800, 1400) of the type comprising: a housing (202) which internally defines the chamber (210) of a cylinder (216), this housing (202) comprising a cover (208) which closes the access to its interior, and gripping members (204), each subjected to a displacement relative to the housing (202) under the effect of the jack (216),

characterized in that the housing (202) further comprises:

a metal jacket (212, 812) which forms the side wall (231) of the chamber (210) of the cylinder (216), and

a body (206), at least partly made of composite material, which encloses the liner (212, 812) so as to form a rigid assembly with the liner (212, 812) and the cover (208).

[Claim 2] A gripper (200, 800, 1400) according to claim 1, wherein the sleeve (212) comprises a base (245) which forms the bottom (215) of the chamber (210) of the cylinder (216), to the front of the body (206).

[Claim 3] A clamp (200, 800, 1400) according to one of claims 1 and 2, wherein the housing (202) further comprises a metal cap (214) sealingly assembled at the rear of the liner (212 ), so as to delimit with the sleeve (212) the chamber of the cylinder (210).

[Claim 4] A clamp (200, 800, 1400) according to one of the preceding claims, wherein the sleeve (212) is threaded into the body (206) and the cover (208) clamps the sleeve (212) against the body (206) so as to form with them a rigid whole.

[Claim 5] Clamp (200, 800, 1400) according to one of the preceding claims, wherein the cover (208) is at least partly made of composite material.

[Claim 6] A clamp (200, 800, 1400) according to one of the preceding claims, wherein the housing (202) comprises a cap (268) partly at the bottom. less in composite material, integral with the body (202), said cap (268) being in connection with the gripping members (204).

[Claim 7] A clamp (200, 800, 1400) according to claim 6, wherein the cap (268) comprises a reinforcing part (306) of composite material, arranged in the center of the cap (268).

[Claim 8] A clamp (200, 800, 1400) according to one of claims 6 or 7, wherein the cap (268) comprises a metal reinforcing ring (308), arranged on the periphery of the cap (268).

[Claim 9] A clamp (200, 800, 1400) according to one of the preceding claims, in which the composite material comprises a material from the family of thermoplastic polymer composites, preferably nylon or nylon copolymer.

[Claim 10] A clamp (200, 800, 1400) according to claim 9, wherein the composite material further comprises poly (p-phenyleneterephthalamide), PPD-T, of the type known as Kevlar, fiber of high temperature high strength carbon, fiberglass or fiberglass, or a combination thereof.

[Claim 11] A clamp (200, 800, 1400) according to claim 10, in which at least one part (206, 208, 268) made of composite material comprises:

- a first portion, which forms an outer envelope (602) of the part (206,

208, 268), of a material from the family of thermoplastic polymer composites, preferably nylon, nylon copolymer, or a combination thereof, and - a second portion of long fibers, which forms a reinforcing structure ( 604) of the part (206, 208, 268), within the outer shell (602), the long fibers comprising Kevlar, carbon, glass, high temperature high strength glass fibers or a combination of these fibers.

[Claim 12] Clamp (200, 800, 1400) according to one of the preceding claims, in which the body (206), the cover (208) or the cap (268) are produced by additive manufacturing.

[Claim 13] Clamp (200, 800, 1400) according to one of the preceding claims, in which the sleeve (212) and / or the cap (214) are made of aluminum.

[Claim 14] A gripper (200, 800, 1400) according to one of the preceding claims further comprising a transmission (228) which transmits the movement of the cylinder (216) to the grippers (204), wherein the transmission (228) ) comprises as many levers (230) as grippers (204), each lever (230) being pivotally mounted in the housing (202) around a circumferential direction, and in which the jack (216) drives the levers (230), and each lever (230) in turn drives its respective gripper (204).

[Claim 15] Clamp (200, 800, 1400) according to any of

preceding claims, comprising a front port (312) and a rear port (314), which supply the chamber (210) with fluid, the front port (312) and the rear port (314) being provided in the body (206). ) so as to open onto the walls of the chamber (210) left free by the jacket (212) and the cover (208).

[Claim 16] Housing (202) for a gripper (200, 800, 1400), of the type internally defining the chamber (210) of a cylinder (216) and comprising a cover (208) which closes access to the cylinder. its interior, the casing (202) being characterized in that it comprises:

[Claim 17] A method of manufacturing a gripper (200, 800, 1400) of the type comprising: a casing (202) which internally defines the chamber (210) of a jack (216), this casing (202) comprising a cover (208) which closes access to its interior, and gripping members (204), each subjected to a displacement relative to the housing (202) under the effect of the jack (216),

the housing (202) further comprising:

a body (206), at least partly made of composite material, which encloses the sleeve (212, 812) so as to form a rigid assembly with the sleeve (212, 812) and the cover (208),

characterized in that the body (206) is produced by additive manufacturing.