Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B31/00—Chucks; Expansion mandrels; Adaptations thereof for remote control
  • B23B31/02—Chucks
  • B23B31/10—Chucks characterised by the retaining or gripping devices or their immediate operating means
  • B23B31/12—Chucks with simultaneously-acting jaws, whether or not also individually adjustable
  • B23B31/20—Longitudinally-split sleeves, e.g. collet chucks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2226/00—Materials of tools or workpieces not comprising a metal
  • B23B2226/33—Elastomers, e.g. rubber
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2231/00—Details of chucks, toolholder shanks or tool shanks
  • B23B2231/20—Collet chucks
  • B23B2231/2086—Collets in which the jaws are formed as separate elements, i.e. not joined together
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2231/00—Details of chucks, toolholder shanks or tool shanks
  • B23B2231/46—Pins

Definitions

• This invention has for an object a clamping chuck which is widely used in machine processes.
• a workpiece must be held in place along a predetermined reference axis so that a machine, for example, a lathe, can perform a mechanical process on the workpiece.
• Another object of this invention is a method for making a clamping chuck.
• clamping chucks comprising a plurality of steel sectors that are interconnected with a plurality of vulcanized rubber sectors to define a housing for the workpiece that is to undergo the machine process.
• a vulcanized rubber sector is interposed between two steel sectors.
• the vulcanized rubber sector is elastically deformable so that the chuck is able to receive and lock the workpiece (or a part thereof) in the housing.
• the vulcanized rubber sectors are deformed and cause the steel sectors to move apart to increase the size of the housing so that the workpiece can be placed inside the housing.
• the vulcanized rubber sectors undergo an elastic return causing the steel sectors to move closer together again so that the chuck closes round the workpiece and locks it in place.
• clamping chucks comprising vulcanized rubber inserts are difficult and expensive to make in that each chuck to be made requires a dedicated mould.
• the steel sectors are placed in the mould and the rubber is then poured into the mould to connect the steel sectors and the rubber ones to each other.
• clamping chucks which comprise sectors made of ordinary rubber instead of vulcanized rubber.
• the rubber sectors are connected to the respective steel sectors by dedicated recesses made in the metal sectors themselves.
• Clamping chucks of this kind also present some disadvantages. More specifically, these clamping chucks are not mechanically stable and tend to grip and hold the workpiece in a manner that is not entirely secure.
• the technical purpose of this invention is to provide a clamping chuck and a method for making the clamping chuck capable of overcoming the above mentioned disadvantages of the prior art.
• This invention therefore has for an aim to provide a clamping chuck that is easy to make and maintain over time.
• Another aim of this invention is therefore to provide a clamping chuck that is inexpensive but at the same time reliable and durable.
• Another aim of this invention is therefore to provide a method for making the clamping chuck and which allows the clamping chuck to be made easily, quickly and efficiently.
• the technical purpose stated and the aims specified are substantially achieved by a clamping chuck and a method for making the clamping chuck comprising the technical features set out in one or more of the appended claims.
• the dependent claims correspond to possible embodiments of the invention.
• a clamping chuck comprising a plurality of first sectors, each of which is laterally delimited by a pair of opposite connecting walls in which respective receiving sockets are formed.
• the chuck also comprises a plurality of second sectors, each of which is laterally delimited by a pair of opposite (connecting) side walls.
• Each second sector comprises a through hole having an inlet section made on one side wall of the pair and an outlet section made on the other connecting wall of the pair of side walls.
• the first and second sectors are angularly distributed alternately around an axis of the chuck so that each connecting wall of a first sector operatively adheres to a side wall of a second sector to define a circular configuration in which the sectors delimit a central socket for insertion of the workpiece that is to undergo a machine process.
• the second sectors are elastically deformable to allow the chuck to move into a contracted configuration in which the second sectors are deformed by compression to cause the first sectors to move closer together.
• the second sectors are made of an elastic material (such as rubber or vulcanized rubber, for example).
• the chuck also comprises a plurality of pins, each provided with a main body and a pair of endpieces.
• Each pin is housed or is able to be housed in a closed housing cavity delimited by a through hole and respective receiving sockets which are operatively aligned with the through hole in such a way that the main body is housed in the through hole and the endpieces are housed in respective receiving sockets.
• each receiving socket is defined by a hole having an insertion portion extending from the connecting wall and a locking portion located at the end of the insertion portion.
• the locking portion is larger in diameter than the insertion portion.
• each endpiece and each receiving socket are shaped in such a way that, in the contracted configuration, when the endpiece of the pin is compressed in the receiving socket, the endpiece is permanently deformed so that the endpiece itself is irreversibly locked in the receiving socket thanks to an undercut.
• the undercut is defined by a shoulder created by the difference between the diameters of the insertion portion and of the locking portion of the receiving socket.
• a pin is inserted into the through hole of each sector in such a way that the endpieces of the pin protrude from the through hole and are inserted into the holes made in the first sectors adjacent to the second sector.
• the pin is inserted in the closed housing cavity defined by the walls of the through hole of the second sector and by the walls of the holes made in the first sectors adjacent to the second sector.
• the chuck When the pin is inserted in this way, the chuck is brought to a contracted configuration so that the second sectors can be elastically deformed to cause the endpieces of each pin to be compressed against an end wall of the respective holes of the first sectors in which they are inserted.
• the endpieces of each pin are squeezed against the end wall of the holes of the first sectors.
• This squeezing action causes a permanent deformation of the endpieces of the pin. More specifically, as a result of the compression, the endpieces increase their transverse dimension, becoming approximately equal in diameter to the locking portion of the holes of the first sectors.
• each endpiece of the pin becomes larger than the transverse dimension of the insertion portion of the holes of the first sectors, thereby preventing the ends of the pin from being disengaged from the first sectors. That way, the main body of the pin is fully inserted in the second sector while the ends are permanently locked to the holes of the first sectors so as to operatively and securely connect the first sectors to the second sector interposed between them.
• the pins are a reliable, stable and durable means of connecting the sectors.
• connecting the sectors by means of the pins avoids using moulds to make the rubber parts and thus reduces the production costs and times of the clamping chuck.
• the chuck may comprise, instead of the pins, at least one pair of connecting elements, distinct from each other and extending away from opposite side walls of a second sector.
• the connecting elements are configured to be inserted into a respective receiving socket and are shaped in such way that, in the contracted configuration, when the connecting element is compressed in the receiving socket, at least one end portion of the connecting element is permanently deformed in the receiving socket so that the endpiece of the connecting element is irreversibly locked in the receiving socket thanks to an undercut.
• a method for making a clamping chuck comprising a step of preparing a plurality of first sectors, each of which is laterally delimited by a pair of opposite connecting walls in which respective receiving sockets are formed.
• the method also comprises a step of preparing a plurality of second sectors made of elastic material and each laterally delimited by a pair of opposite (connecting) side walls.
• Each second sector is provided with a through hole having an inlet section made on one side wall of the pair of side walls and an outlet section made on the other side wall of the pair of side walls.
• the method also comprises a step of preparing a plurality of pins, each provided with a main body and a pair of endpieces.
• the method also comprises a step of angularly distributing the first and second sectors alternately around an axis of the chuck so that each connecting wall of a first sector operatively adheres to a side wall of a second sector to define a circular configuration in which the sectors delimit a central socket for insertion of a workpiece that is to undergo a machine process.
• the method also comprises a step of fixedly coupling a first sector to a second sector by engaging each pin in a closed housing cavity delimited by a through hole and respective receiving sockets which are operatively aligned with the through hole in such a way that the main body of the pin is housed in the through hole and the endpieces of the pin are housed in respective receiving sockets.
• the method also comprises a step of compressing each endpiece of the pin in the respective receiving socket in such a way that engagement is accomplished by permanently deforming the endpiece of the pin in the receiving socket to irreversibly lock the endpiece of the pin in the receiving socket thanks to an undercut.
• the step of preparing a plurality of first sectors comprises a sub-step of making at least one hole to define the receiving socket. More specifically, the hole has an insertion portion extending from the connecting wall and a locking portion located at the end of the insertion portion and being larger in diameter than the insertion portion so that the undercut is defined by a shoulder created by the difference between the diameters.
• deforming consists in increasing the transverse dimension of the ends of the pin so it is approximately equal to the locking portion in diameter.
• the ends of the pin have a transverse dimension that is larger than the diameter of the insertion portion and are thus locked inside the holes, specifically inside the locking portions, of the first sectors by the undercut formed by the difference between the diameters of the insertion portion and of the locking portion.
• the first and second sectors are operatively connected fixedly to each other because the ends of each pin are locked inside the holes of the first sectors.
• the method for making the clamping chuck is simple, reliable and fast.
• FIG. 1 shows an exploded perspective view of the clamping chuck of this disclosure
• FIG. 2 shows a perspective view of the chuck of Figure 1 ;
• FIG. 3 shows a cross sectional view of the clamping chuck of this disclosure
• Figure 3A is an enlarged view of a detail from Figure 3.
• the letter P denotes a clamping chuck used to hold a workpiece that is to undergo a machine process such as lathing, for example.
• the clutch P comprises a plurality of first sectors 100, each of which is laterally delimited by a pair of opposite connecting walls 101 in which respective receiving sockets 102 are formed.
• each of the first sectors 100 is provided with two receiving sockets 102 on each connecting wall 101 , located one under the other along a direction parallel to an axis A of the chuck P.
• each of the first sectors 100 is provided with any number of receiving sockets 102 on each connecting wall 101.
• the first sectors 100 are made from a metallic material, specifically steel.
• the chuck P also comprises a plurality of second sectors 200, each laterally delimited by a pair of opposite (connecting) side walls 201.
• Each second sector 200 is also provided with a through hole 302 having an inlet section made on one side wall 201 of the pair and an outlet section made on the other side wall 201 of the pair of side walls.
• the second sectors 200 are made of rubber, specifically vulcanized rubber.
• the chuck P also comprises a plurality of pins 300, preferably rivets, each provided with a main body 301 and a pair of endpieces 303.
• Each pin 300 is housed or is able to be housed in a closed housing cavity delimited by a through hole 302 and respective receiving sockets 102 which are operatively aligned with the through hole 302 in such a way that the main body 301 of the pin 300 is housed in the through hole 302 and the endpieces 303 of the pin 300 are housed in respective receiving sockets 102.
• the second sectors 200 each have two through holes 302, located one under the other in such a way as to be operatively aligned with respective receiving sockets 102 of the first sectors 100 to define closed housing cavities for the respective pins 300.
• the first and second sectors 100, 200 are angularly distributed alternately around the axis A of the chuck P so that each connecting wall 101 of a first sector 100 operatively adheres to a side wall 201 of a second sector 200 to define a circular configuration in which the sectors 100, 200 delimit a central socket S for insertion of the workpiece that is to undergo a machine process.
• each pin 300 is inserted into the respective housing cavity so that the endpieces 303 are placed inside the receiving sockets 102 and the main body 301 is placed inside the through hole 302 so as to allow the connecting walls 101 and side walls 201 of the sectors 100, 200 to adhere to each other.
• the first and second sector 100, 200 are engaged with each other and act in conjunction to define the central socket S into which a workpiece must be inserted to be held by the chuck P.
• the central insertion socket S has, in cross section, a substantially circular shape suitable for accommodating a workpiece having a round cross section.
• the first sectors 100 are shaped like respective sectors of a circular crown, while the second sectors 200 are shaped substantially like an upturned L.
• the central insertion socket S may in, cross section, have any polygonal shape so that it can adapt to the cross sectional shape of the workpiece to be held during a machine process.
• the second sectors 200 are also elastically deformable to allow movement of the chuck P.
• the chuck P may adopt an insertion configuration in which the second sectors 200 are deformed by traction so that the first sectors 100 are moved apart to allow the workpiece to be inserted into the central insertion socket S.
• the chuck P may also adopt a contracted configuration in which the second sectors 200 are deformed by compression to cause the first sectors 100 to move closer together. This configuration is useful to obtain a secure and steady operative connection between the first sectors 100 and the second sectors 200.
• each endpiece 303 of a pin 300 interacts with the respective receiving socket 102 in such a way as to securely and irreversibly connect the first sectors 100 to the second sectors 200.
• each endpiece 303 and each receiving socket 102 are shaped in such a way that, in the contracted configuration, when the endpiece 303 of the pin 300 is compressed in the receiving socket 102, the endpiece 303 is permanently deformed in the receiving socket 102 so that the endpiece 303 of the pin 300 is irreversibly locked in the receiving socket 102 thanks to an undercut.
• each second sector 200 is set up in such a way as to accommodate the main body 301 of a pin 300 in the through hole 302 so that the endpieces 303 protrude relative to the side walls 201 of the second sector 200.
• each endpiece 303 of each pin 300 is inserted into a respective receiving socket 102 that is aligned with and faces the through hole 302 into which the pin 300 is inserted. That way, the connecting walls 101 of the first sectors 100 operatively adhere to respective side walls 201 of the second sectors 200 and the pins 300 are inserted into respective closed housing cavities delimited by the through hole 302 and by the receiving sockets 102 that are operatively aligned therewith. In this situation, the chuck P is brought to the contracted configuration, thereby applying a squeezing action on the second sectors 200 and moving the first sectors 100 closer together.
• each receiving socket 102 When the first sectors 100 move towards each other, each receiving socket 102 abuts with a respective endpiece 303 of the pin 300 and applies thereon a compressive or squeezing force capable of causing it to undergo permanent deformation (that is, a type of plastic deformation).
• a compressive or squeezing force capable of causing it to undergo permanent deformation (that is, a type of plastic deformation).
• the chuck P returns to the rest configuration, that is to say, a configuration in which the second sectors 200 are not elastically deformed and the endpieces 303 of each pin 300 are deformed and irreversibly locked in the receiving sockets 102, thereby ensuring a secure, operative connection between the first sectors 100 and the second sectors 200.
• the chuck P can be moved between the rest configuration and the insertion configuration so that the workpiece can be inserted and extracted without the risk of the first sectors 100 being disengaged or separated from the second sectors 200.
• each receiving socket 102 is defined by a hole, specifically a blind hole, having an insertion portion 102b extending from the connecting wall 101 and a locking portion 102a located at the end of the insertion portion 102b ( Figure 3) and being larger in diameter than the insertion portion 102b. More specifically, each hole has a depth such that, in the contracted configuration, the endpiece 303 of the pin 300 can be mechanically stopped against an end wall of the hole.
• the endpieces 303 of the pins 300 inserted in the receiving sockets 102 are each in contact with the end wall of the hole of the respective first sector 100.
• the end wall applies on the endpiece 303 a squeezing/compressive action such as to cause the endpiece 303 to undergo irreversible deformation.
• the endpieces 303 are thus irreversibly deformed in the respective receiving sockets 102 and the transverse dimension of each of them becomes approximately equal to the diameter of the locking portion 102a. In this situation, the endpieces 303 are unable to come out of the receiving sockets 102 because the insertion portion 102b is smaller in diameter than the transverse dimension of the respective endpiece 303 and is prevented from being disengaged therefrom.
• the diameter difference produces a shoulder that defines an undercut that irreversibly locks the endpiece 303 in the receiving socket 102 when the endpiece 303 of the pin 300 is compressed.
• the receiving socket 102 to facilitate compressing the endpieces 303 of each pin 300, the receiving socket 102, specifically the end wall of the hole, is provided with a protrusion (not illustrated) defining a deforming protuberance which, in the contracted configuration, is configured to come into abutment with a respective endpiece 303 of the pin 300, causing it to undergo permanent deformation.
• each pin 300 has its main body 301 inserted in the through hole 201 and its endpieces 303 inserted in a respective hole in a first sector 100.
• the endpieces 303 extend towards the locking portion 102a through the insertion portion 102b until coming into contact (or substantially in contact) with the end wall of the hole.
• the first sectors and the second sectors 200 are fixedly locked to each other.
• each pin 300 comprises a pair of balls 304, each operatively associated with a respective endpiece 303 and configured, in the contracted configuration, to abut against the receiving socket 102 of the first sector 100.
• each endpiece 303 has a substantially cup-shaped cavity configured to receive a respective ball 304.
• each receiving socket 102 of the first sectors 100 moves towards and into contact with a respective ball 304 in such a way as apply a compressive action on the ball 304 so it deforms the cup-shaped cavity of the endpieces 303 of each pin 300.
• the balls 304 are recessed or embedded in the cup-shaped cavity which, instead, now has a flattened shape and is mechanically locked to the receiving socket 102 of the first sector 100.
• the balls 304 protrude from the cup-shaped cavity, ready to be pressed into respective receiving portions 102 of the first sectors 100.
• the balls 304 are embedded between the locking portion 102a and the insertion portion 102b while the cup-shaped cavity is now flattened against the undercut defined by the difference between the diameters of the locking portion 102a and the insertion portion 102b.
• the pins 300 are embedded and fixedly retained in the deformable material of the second sector 200 during a process of making the second sector 200, specifically by a vulcanization process.
• the pins 300 can be inserted into the through hole 302 of each second sector 200 after the second sector 200 has been made.
• the fact that the second sectors 200 can be made separately from the pins 300 allows simplifying the production process of the second sectors 200 themselves. More specifically, the pins 300 need not be embedded in the rubber at the same time as the second sectors 200 are made but can be inserted into the through holes 302 in the second sectors 200 at a later stage.
• a pin 300 is inserted into each through hole 302 of each second sector 200 in such a way that the main body 301 is inside the through hole 302 while the endpieces 303 protrude from the through hole 302.
• the endpieces 303 of the pins 300 are inserted into respective receiving sockets 102 in such a way that the entire pin 300 is inside a closed housing cavity defined by the receiving sockets 102 and by the through hole 302.
• the chuck P is brought to the contracted configuration, causing the endpieces 303 of the pins 300 to undergo permanent deformation.
• the endpiece 303 of each pin 300 is plastically deformed by interaction with the receiving socket 102 so as to be lodged between the locking portion 102 and the insertion portion 102b.
• the endpiece 303 has a transverse cross section that is the same (or substantially the same) in size as the diameter of the locking portion 102a and is thus prevented from passing through the insertion portion 102b which is smaller in diameter. This prevents the sectors 100, 200 from being disengaged from each other and allows the pins 300 to keep them firmly together.
• the side walls 201 of the second sectors 200 and the connecting walls 101 of the first sectors 100 are at least partly shaped to match each other to create a shape coupling between the first and the second sectors 100, 200.
• the first sectors 100 are provided with hollows configured to receive respective protrusions of the second sectors 200 so as to create a shape coupling between the first and second sectors 100, 200.
• the fact that the first and second sectors 100, 200 are shaped to match each other contributes to the stability of the operative connection, provided by the pins 300, between the sectors 100, 200.
• This disclosure also has for an object a method for making a clutch P comprising step of preparing a plurality of first sectors 100, each of which is laterally delimited by a pair of opposite connecting walls 101 in which respective receiving portions 102 are formed.
• the method also comprises a step of preparing a plurality of second sectors 200 made of an elastic material.
• Each of the second sectors 200 is laterally delimited by a pair of opposite side walls 201.
• Each second sector 200 is also provided with a through hole 302 having an inlet section made on one side wall 201 of the pair of side walls and an outlet section made on the other side wall 201 of the pair of side walls.
• the method also comprises a step of preparing a plurality of pins 300, preferably rivets, each provided with a main body 301 and a pair of endpieces 303.
• the method also comprises a step of angularly distributing the first and second sectors 100, 200 alternately around an axis A of the chuck P so that each connecting wall 101 of a first sector 100 operatively adheres to a side wall 201 of a second sector 200 to define a circular configuration in which the sectors delimit a central socket S for insertion of a workpiece that is to undergo a machine process.
• the method comprises a step of fixedly coupling a first sector 100 to a second sector 200 by engaging each endpiece 303 of the pin 300 in a respective receiving socket 102 with its main body 301 inside the through hole 302 when the through hole is operatively aligned with the respective receiving socket 102.
• each pin 300 is inserted into a closed housing cavity defined by the respective through hole 302 and receiving socket 102.
• the method also comprises a step of compressing each endpiece 303 of the pin 300 in the respective receiving socket 102 in such a way that engagement is accomplished by permanently deforming the endpiece 303 of the pin 300 in the receiving socket 102 to irreversibly lock the endpiece 303 of the pin 300 in the receiving socket 102 thanks to an undercut.
• each receiving socket 102 applies a squeezing action on a respective endpiece 303 of the pin 300 inserted in it, thereby causing it to undergo permanent deformation. That way, the endpiece 303 is prevented from being disengaged from the receiving socket 102.
• the pin 300 is locked both to the second sector 200, since the main body 301 is inserted in the blind hole 302, and to the first sector 100, since the endpieces 303 are locked in respective receiving sockets 102, thus obtaining a steady operative connection between the sectors 100, 200.
• the step of preparing a plurality of first sectors 100 comprises a sub-step of making, for each first sector 100, at least one hole, preferably a blind hole, to define the receiving socket 102.
• the hole has an insertion portion 102b extending from the connecting wall 101 and a locking portion 102a located at the end of the insertion portion 102b.
• the locking portion 102a is larger in diameter than the insertion portion 102b so that the undercut is defined by a shoulder created by the difference between the diameters.
• each pin 300 is inserted into a through hole 302 so that the endpieces 303 extend through the insertion portion 102b to reach the locking portion 102a.
• the receiving socket 102 specifically an end wall of the hole
• the endpiece 303 of the pin 300 is too large to pass through the insertion portion 102b of the hole and is thus locked inside the hole. That way, the pin 300 is integral with the second sector 200 and its endpieces 303 are fixedly locked to the first sectors 100 in such a way as to fixedly connect the first sectors 100 to the second sector 200.
• the step of preparing a plurality of pins 300 comprises a sub-step of coupling a ball 304 to each endpiece 303 of each pin 300.
• the ball 304 is configured to abut against a corresponding receiving socket 102 of a first sector 100.
• each endpiece 303 has a substantially cup-shaped cavity configured to receive a respective ball 304.
• each receiving socket 102 of the first sectors 100 moves towards and into contact with a respective ball 304 in such a way as apply a compressive action on the ball 304 so it deforms the cup shaped cavity of the endpieces 303 of each pin 300.
• the balls 304 are recessed or embedded in the cup-shaped cavity which, instead, now has a flattened shape and is abutted against the undercut of the receiving socket 102 and thus mechanically locked inside the first sector 100.
• the method also comprises, prior to the steps of preparing the first and second sectors 100, 200, a step of giving the side walls 201 of the second sectors 200 a contoured shape and a step of giving the connecting walls 101 of the first sectors 100 a matching contoured shape so as to create a shape coupling between the first and second sectors 100, 200 in the step of coupling.
• the connecting walls 101 and the side walls 201 of the first and second sectors 100, 200 are respectively contoured to match each other so as to form a shape coupling between the first and second sectors 100, 200 capable of further stabilizing the operative connection created by the pins 300 between the sectors 100, 200, making it more durable.
• This invention achieves the preset aims and overcomes the disadvantages of the prior art.
• the possibility of deforming the endpieces 303 of the pins 300 makes the chuck P easy to assemble.
• the pin 300 is able to join in a mechanically stable manner a second sector 200 to first sectors 100 because the whole of its main body 301 is inserted in the second sector 200 while its endpieces 303 are permanently deformed inside the receiving portions 102 of the first sectors 100.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Snaps, Bayonet Connections, Set Pins, And Snap Rings (AREA)

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Publications (1)

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• 2022
  • 2022-03-24 WO PCT/IB2022/052712 patent/WO2022201092A1/en active Application Filing
  • 2022-03-24 EP EP22712081.3A patent/EP4313455A1/de active Pending

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