EP4313455A1 - Clamping chuck and method for making a clamping chuck - Google Patents

Clamping chuck and method for making a clamping chuck

Info

Publication number
EP4313455A1
EP4313455A1 EP22712081.3A EP22712081A EP4313455A1 EP 4313455 A1 EP4313455 A1 EP 4313455A1 EP 22712081 A EP22712081 A EP 22712081A EP 4313455 A1 EP4313455 A1 EP 4313455A1
Authority
EP
European Patent Office
Prior art keywords
sectors
pin
hole
chuck
endpiece
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22712081.3A
Other languages
German (de)
French (fr)
Inventor
Luca CHIARI
Fabio CHIARI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chia Mo Srl
Original Assignee
Chia Mo Srl
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chia Mo Srl filed Critical Chia Mo Srl
Publication of EP4313455A1 publication Critical patent/EP4313455A1/en
Pending legal-status Critical Current

Links

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.

Abstract

A clamping chuck (P) comprises a plurality of first sectors (100), each provided with respective receiving sockets (102). The chuck (P) also comprises a plurality of second sectors (200), each provided with a through hole (302). The first and second sectors (100, 200) are angularly distributed alternately around an axis (A) of the chuck (P) and the second sectors (200) are elastically deformable to allow the chuck (P) to move into a contracted configuration, wherein the second sectors (200) are deformed by compression to cause the first sectors (100) to move closer together. The chuck (P) also comprises a plurality of pins (300), each provided with a main body (301) and a pair of endpieces (303), each pin (300) being housed or able to be housed in a closed housing cavity delimited by a respective through hole (302) and respective receiving sockets (102) operatively aligned with the through hole (302).

Description

DESCRIPTION
CLAMPING CHUCK AND METHOD FOR MAKING A CLAMPING
CHUCK
Technical field
This invention has for an object a clamping chuck which is widely used in machine processes. In such 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.
Background art
Known in the prior art up to the present are 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.
Examples of these chucks are described in the following patent documents: DE19509921 A1 , US3217519A, US4309041A, US4867463A, US5865073A, US9447823B2, EP1523392, GB1295827A,
US10953478B2, US4736957A, US3750452A, FR2868715A1 and
US5253506A.
In these chucks, 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.
In effect, in this situation, when the workpiece to be machined is placed in the chuck, 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. Next, 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.
Disadvantageously, clamping chucks comprising vulcanized rubber inserts are difficult and expensive to make in that each chuck to be made requires a dedicated mould. In this situation, 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.
Another disadvantage is due to the fact that the vulcanized rubber deteriorates over time and tends to come away from the steel sectors between which it is interposed. In this situation, repairing the damaged sector is difficult and costly.
Also known in the prior art are clamping chucks which comprise sectors made of ordinary rubber instead of vulcanized rubber. In these chucks, 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.
Disclosure of the invention
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.
More specifically, the technical purpose stated and the aims specified are achieved by 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. In one example, 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.
According to an aspect of this disclosure, 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.
According to another aspect of this disclosure, 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. According to another aspect of this disclosure, 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.
In use, therefore, 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. In this situation, 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.
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. In this situation, 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.
In other words, the transverse dimension of 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. Advantageously, the pins are a reliable, stable and durable means of connecting the sectors.
Advantageously, 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.
According to another aspect of this disclosure, for each second sector, 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. In this embodiment, 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.
The technical purpose stated and the aims specified are also achieved by 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.
According to an aspect of this disclosure, 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.
In this situation, when the step of distributing the sectors and the step of coupling are over, the chuck is moved into a contracted configuration in which the second sectors are elastically deformed by compression. In this situation, an end wall of the holes of the first sectors applies a squeezing action on the endpieces of the pin, thereby causing them to be permanently deformed. More specifically, deforming consists in increasing the transverse dimension of the ends of the pin so it is approximately equal to the locking portion in diameter.
In this situation, 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.
Thus, when the chuck moves into a rest configuration, that is, when the compressing action on the second sectors is stopped, 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.
Advantageously, the method for making the clamping chuck is simple, reliable and fast.
Brief description of drawings
Further features of the invention and its advantages are more apparent in the exemplary description below, with reference to a preferred embodiment of a clamping chuck and of a method for making the clamping chuck.
The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without limiting the scope of the invention and in which:
- Figure 1 shows an exploded perspective view of the clamping chuck of this disclosure;
- Figure 2 shows a perspective view of the chuck of Figure 1 ;
- Figure 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.
Detailed description of preferred embodiments of the invention With reference to the accompanying drawings, 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.
In the embodiment shown in the accompanying drawings, 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.
Alternatively, each of the first sectors 100 is provided with any number of receiving sockets 102 on each connecting wall 101.
According to an aspect of this disclosure, 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.
According to an aspect of this disclosure, 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.
In the embodiment shown in the accompanying drawings, 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.
As shown in the accompanying drawings, 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.
More specifically, when the sectors 100, 200 are positioned, 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. In this situation, 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.
In the embodiment shown in the accompanying drawings, the central insertion socket S has, in cross section, a substantially circular shape suitable for accommodating a workpiece having a round cross section.
In this situation, as shown in Figures 1 and 2, 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.
Alternatively, 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.
According to another aspect of this disclosure, the second sectors 200 are also elastically deformable to allow movement of the chuck P.
In detail, 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.
In effect, in the contracted configuration, 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.
According to an aspect of this disclosure, 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.
In use, 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.
During setting up of the first and second sectors 100, 200 according to an angular, alternating distribution around the axis A of the chuck P, 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. 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). In this situation, when 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. Once the endpieces 303 of each pin 300 have been deformed, 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.
In the embodiment shown in the accompanying drawings, 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.
In use, when the second sectors 200 are deformed, 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. In this situation, the end wall applies on the endpiece 303 a squeezing/compressive action such as to cause the endpiece 303 to undergo irreversible deformation.
As shown in Figure 3A, 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.
In other words, 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.
According to an aspect of this disclosure, 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.
In use, therefore, 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. In this situation, 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.
As the chuck P moves into the contracted configuration, the second sectors 200 are drawn together, thereby causing the first sectors 100 to move towards each other. In this situation (Figure 3A), the end wall of the hole applies on the endpiece 303 a compressive action that causes a squeezing action that subjects it to permanent deformation. This deformation, as shown in Figure 3A, produces an increase in the transverse dimension of the endpiece 303 to become approximately equal to the diameter of the locking portion 102a of the hole. In this situation, therefore, the endpieces 303 of each pin 300 are prevented from being disengaged from the locking portion 102a and thus from coming out of the holes since the dimension of their transverse cross section is greater than the diameter of the insertion portions 102b facing them.
Advantageously, thanks to the increased dimensions of the endpieces 303 of the pins 300 as a result of the compression applied by the deformation of the second sectors 200, the first sectors and the second sectors 200 are fixedly locked to each other.
According to an aspect of this disclosure, as shown in Figure 1, 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.
More in detail, each endpiece 303 has a substantially cup-shaped cavity configured to receive a respective ball 304.
During compression of the second sectors 200, 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. Looking in more detail, as shown in Figure 3A, when the receiving portions 102 of the first sectors 100 stop applying the compressive action, 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.
As shown in Figure 1, prior to compression, the balls 304 protrude from the cup-shaped cavity, ready to be pressed into respective receiving portions 102 of the first sectors 100.
After compression, as shown in Figure 3A, 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.
According to another aspect of this disclosure, 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.
Alternatively, the pins 300 can be inserted into the through hole 302 of each second sector 200 after the second sector 200 has been made. Advantageously, 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.
In use, therefore, 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.
During positioning of the first and second sectors 100, 200 to define the central insertion socket S, 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.
Next, the chuck P is brought to the contracted configuration, causing the endpieces 303 of the pins 300 to undergo permanent deformation. Looking in more detail, 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. In effect, in this situation, 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.
To enhance the stability and durability of the connection between the first and second sectors 100, 200, 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.
Looking in more detail, as shown in Figure 1 , 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.
Advantageously, 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.
After the step of distributing, 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.
In other words, in the step of coupling, 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.
In other words, after the step of coupling, the second sectors 200 are elastically deformed in such a way as to cause the first sectors 100 to move closer together. In this situation, 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. In this situation, 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.
According to an aspect of this disclosure, 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.
In use, therefore, in the step of coupling, 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. In this situation, in the step of compressing, the receiving socket 102, specifically an end wall of the hole, applies on the endpiece 303 of the pin 300 a compressive or squeezing action such as to cause it to undergo permanent deformation. More specifically, this permanent deformation produces an increase in the transverse dimension of the endpiece 303 of the pin 300 to become approximately equal to the diameter of the locking portion 102a. In this situation, 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.
According to another aspect of this disclosure, 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.
More in detail, each endpiece 303 has a substantially cup-shaped cavity configured to receive a respective ball 304.
During the step of coupling, 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. Looking in more detail, as shown in Figure 3A, when the step of compressing is over, 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.
According to another aspect of this disclosure, 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.
In other words, 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 possibility of deforming the endpieces 303 of the pins 300 makes the connection between the sectors 100, 200 stable and durable. In effect, in this situation, 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.

Claims

1. A clamping chuck (P) for clamping a workpiece intended for machining, comprising:
- a plurality of first sectors (100), each laterally delimited by a pair of opposite connecting walls (101) in which respective receiving sockets (102) are formed;
- a plurality of second sectors (200), each laterally delimited by a pair of opposite side walls (201) provided with a through hole (302) which opens on the side walls of the pair of side walls (201), wherein the first and second sectors (100, 200) are angularly distributed alternately around an axis (A) of the chuck (P) so that the connecting walls (101) of each first sector (100) are operatively in contact with corresponding side walls (201) of respective second sectors (200) to define a circular configuration in which the first and second sectors (100, 200) delimit a central socket (S) for insertion of the workpiece, and wherein the second sectors (200) are elastically deformable to allow the chuck (P) to move into a contracted configuration in which the second sectors (200) are close together;
- a plurality of pins (300), each provided with a main body (301) and a pair of endpieces (303), each pin (300) being housed in a corresponding closed housing cavity formed of a respective through hole (302) and respective receiving sockets (102) operatively aligned with the through hole (302), so that the main body (301) of the pin (300) is housed in the respective through hole (302) and the endpieces (303) are housed in the respective receiving sockets (102).
2. The chuck according to claim 1 , wherein the receiving socket (102) is defined by a 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), the locking portion (102a) being larger in diameter than the insertion portion (102b).
3. The chuck according to claim 2, wherein 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.
4. The chuck according to any one of the preceding claims, wherein each endpiece (303) and each receiving socket (102) are shaped in such a way that, in the contracted configuration, when the endpiece (303) is compressed in the receiving socket (102), the endpiece (303) is permanently deformed so that the endpiece (303) of the pin (300) is irreversibly locked in the receiving portion (102) thanks to an undercut.
5. The chuck according to any one of the preceding claims, wherein each pin (300) comprises a pair of balls (304), each operatively associated with a respective endpiece (303) of the pin (300) and configured, in the contracted configuration, to abut against the receiving socket (102).
6. The chuck according to any one of the preceding claims, wherein the receiving socket (102) is provided with a protrusion defining a deforming abutment configured, in the contracted configuration, to come into abutment against the endpiece (303) of the pin (300).
7. The chuck according to any one of the preceding claims, wherein the first sectors (100) are made of metallic material.
8. The chuck according to any of the preceding claims, wherein the second sectors (200) are made of rubber, specifically vulcanized rubber.
9. The chuck according to any of the preceding claims, wherein the second sectors (200) are made of an elastic material.
10. The chuck according to any of the preceding claims, wherein the pins (300) are embedded and fixedly retained in the deformable material of the respective second sector (200) during a process of making the second sector (200), specifically by a vulcanization process.
11. The chuck according to any one of the preceding claims, wherein 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).
12. A method for making a clamping chuck (P) for clamping a workpiece intended for machining, comprising the following steps:
- preparing a plurality of first sectors (100), each laterally delimited by a pair of opposite connecting walls (101) in which respective receiving sockets (102) are formed;
- preparing a plurality of second sectors (200), made of elastic material, each laterally delimited by a pair of opposite side walls (201) provided with a through hole (302) which opens on the side walls of the pair of side walls;
- preparing a plurality of pins (300), each provided with a main body (301) and a pair of endpieces (303);
- disposing the first and second sectors (100, 200) according to an alternate angular distribution around an axis (A) of the chuck (P) so that each connecting wall (101) of a first sector (100) is in contact with a corresponding side wall (201) of a second sector (200) to define a circular configuration in which the first and second sectors delimit a central socket (S) for insertion of the workpiece;
- fixedly coupling each first sector (100) to the second sectors (200) adjacent thereto by inserting a pin (300) into a corresponding closed housing cavity delimited by the through hole (302) of that first sector (100) and respective receiving sockets which are operatively aligned with the through hole (302), so 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 the respective receiving sockets (102).
13. The method according to claim 12, comprising a step of moving the chuck into the contracted configuration so that, for each pin (300), the endpieces (303) mechanically interact with the respective receiving sockets (102) to permanently deform the endpieces (303) so as to irreversibly lock each endpiece (303) of the pin (300) in the respective receiving socket (102) thanks to an undercut.
14. The method according to claim 13, wherein at least one hole defining the receiving socket (102) is formed on each first sector (100), the 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), the locking portion (102a) being larger in diameter than the insertion portion (102b) so that the undercut is defined by a shoulder created by the difference between the diameters.
15. The method according to one or more of claims 12 to 14, wherein each endpiece (303) of each pin (300) is coupled with a ball (304), configured to abut against the corresponding receiving socket (102).
16. The method according to one or more of claims 12 to 15, further comprising the following steps:
- forming a shape on the side walls (201) of the second sectors (200);
- forming a matching shape on the connecting walls (101) of the first sectors (100) to create a shape coupling between the first and the second sectors (100, 200) during the step of coupling.
EP22712081.3A 2021-03-26 2022-03-24 Clamping chuck and method for making a clamping chuck Pending EP4313455A1 (en)

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CN117102905B (en) * 2023-10-18 2024-01-26 万向钱潮股份公司 Clamping mechanism for clamping outer circle

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