EP3843922A1

EP3843922A1 - Gripper having an interchangeable head, and tool comprising same

Info

Publication number: EP3843922A1
Application number: EP18765590.7A
Authority: EP
Inventors: Clovis CHETELAT
Original assignee: Wibemo SA
Current assignee: Wibemo SA
Priority date: 2018-08-29
Filing date: 2018-08-29
Publication date: 2021-07-07
Also published as: US20210323142A1; WO2020043283A1

Abstract

The present invention relates to a gripper having an interchangeable head, comprising: • a body (1) defining a longitudinal axis, having a first end (1a) intended to be fitted in a nut (2) and a second, free end (1b) provided with sectors (11) that are able to deform elastically in a radial direction and are intended to receive a removable head, • a thrust pin (3) mounted inside said body (1) so as to be able to slide along said longitudinal axis in a first direction under the effect of a driving force transmitted through the nut by a kinematic connection means and in a second direction under the effect of a spring member (7), • a plurality of lugs (4) that are mounted securely and in a regular angular arrangement on the thrust pin (3) and protrude radially from the surface of said thrust pin through the body (1) of the gripper. According to the invention, said lugs (4) are arranged fixedly in a longitudinal and radial position on the thrust pin (3) by way of a fixing means (9).

Description

INTERCHANGEABLE HEAD CLAMP AND TOOL COMPRISING THE SAME

Technical area

The present invention relates to the field of machining. It relates, more particularly, to an interchangeable head pliers adapted to be used in a machining device, in particular of the machining tower type.

State of the art

Known tools are provided with interchangeable tip clamps arranged to perform clamping from the outside. These tools include a spindle and a clamp comprising a body and a thrust axis as mentioned above. A socket is movably mounted outside the body, between the latter and the spindle. The clamp has a clamping cone making it possible, when the sleeve moves, to reduce the diameter of the clamp to effect clamping from the outside. This type of pliers is known to the skilled person under the name of type F pliers.

However, this type of tool and pliers is not suitable for machining certain complex parts, particularly when it is necessary to machine a part over its entire length, without the possibility of gripping the part by its two extremities. It is then necessary to take the part from the other side, when possible, which poses problems of concentricity and which can also mark previously machined parts of the part.

There are pliers for gripping a workpiece from the inside thereof, that is to say by inserting the end of the pliers inside a cavity of the workpiece. The Applicant has proposed such a clamp in the patent

EP. However, the machining precision of the parts held using such pliers tends to deteriorate over time, in particular following service operations and / or dismantling of the pliers, due to the play and offsets induced by dismantling. / reassembly between the modular parts of the clamp, in particular the conical support elements of the clamp in the spindle of the machining device.

The present invention aims to solve these drawbacks. Disclosure of invention

To achieve this object, the invention provides an interchangeable head clamp comprising:

- a body defining a longitudinal axis, comprising a first end intended to be adjusted in a nut and a second, free end, endowed with sectors able to deform elastically, in a radial direction and intended to receive a removable head,

a thrust axis mounted sliding along said longitudinal axis inside said body, in a first direction under the effect of a driving force transmitted through the nut by a kinematic connection means and in a second direction under the effect of an organ comes out,

- A plurality of lugs mounted integrally and in a regular angular arrangement on the thrust axis and projecting radially from the surface of said thrust axis through the body of the clamp.

Characteristically and advantageously, the clamp of the invention is characterized in that the said pins are fixedly arranged in the longitudinal and radial position on the thrust axis by a fitting means.

The provision of a means for embedding the lugs on the thrust axis advantageously makes it possible to provide a reference for invariant positioning and mounting of said lugs on the thrust axis, which provides a singular improvement in precision. of the clamp in use. This reference makes it possible to guarantee, even in the event of service and disassembly of the clamp, that the pins will always be equidistant from the ends of the body of the clamp and in the same radial position on the thrust axis, which is not not possible with the simple fixing by screws of the clamps of the prior art. This achieves machining precision at the factory on the order of 1 hundredth on the machined parts, when with the pliers of the prior art this precision was at best 5 hundredths. In one embodiment, said body comprises oblong openings through which the pins (4) project from the thrust axis.

In one embodiment, the embedding means is a pin driven into a blind hole formed in said lugs and adapted to fit into an orifice of corresponding diameter in the thrust axis.

In one embodiment, said sectors define a mounting cradle without play of a clamp head having n deformable sectors capable of being secured to the sectors of the body of the clamp by screwing.

In one embodiment, said lugs are fixed on the thrust axis on flats formed in the head of the thrust axis.

In one embodiment, said lugs are locked in rotation on the thrust axis by screwing in a hole drilled on said thrust axis.

In one embodiment, the embedding and screwing holes of said lugs are drilled parallel to each other from the an external surface of said flats and open into an internal cavity of the thrust axis.

In one embodiment, said lugs comprise a screw tab having a through screw hole on the thrust axis and a tooth integral with said screw tab and having an external support plane inclined at an angle compared to a common base of the screw tab and the tooth.

In one embodiment, said blind hole for driving out the pin is drilled in the tooth along an axis parallel to that of the screw hole.

In one embodiment, the cradle for mounting the removable head delimited by the sectors of the body has an internal planar guide surface and the removable head a mounting sleeve for a planar external surface and a diameter equal to the internal diameter of the mounting cradle.

The invention also relates to a machining device comprising an interchangeable head pliers as defined above.

Brief description of the drawings Other details of the invention will appear more clearly on reading the description which follows, made with reference to the accompanying drawings in which:

FIGS. 1 and 2 are respectively perspective and longitudinal section views of pliers according to the invention, and

- Figures 3A and 3B are respectively top views and in longitudinal section of a conical lug for the clamp according to the invention;

- Figures 4 to 6 are respectively views from above, in longitudinal section and from the front of a thrust axis of the clamp according to the invention;

- Figures 7 and 8A, 8B are perspective, side and cross-sectional views of an interchangeable pliers head for the pliers of the invention.

Mode (s) of carrying out the invention

There is shown in Figures 1 and 2, an interchangeable head pliers according to the invention in a preferred embodiment. This clamp comprises a body 1, cylindrical, defining a longitudinal axis shown in phantom in these figures. At a first end 1a of the body 1, the clamp is arranged to be adjusted in a spindle of a tool or of a device or machine tool. Those skilled in the art know how such a plier can be thus inserted into a machine tool, without it being necessary to describe it in detail. At this end 1a, the body 1 is integral with a nut 2, allowing, on the one hand, the connection of the clamp to a said machine tool and, on the other hand, guiding and positioning the body 1.

The wall of the body 1 is pierced with oblong openings 8, oriented longitudinally along generatrices parallel to the longitudinal axis of the body 1. In the example illustrated, the wall of the body 1 is advantageously pierced with three openings 8, regularly distributed around the body 1. The role of these openings 8 will appear below.

The body 1 is also split on the side of its second end 1b, along the longitudinal axis, so as to define sectors 11 capable of deforming elastically, in a radial direction. The slots are advantageously made in the extension of the openings 8.

At its second end 1b, end which is free when the pliers are inserted into the spindle of a machine tool, the body 1 comprises a housing 12 intended to receive an interchangeable clamping head 13, as shown in detail in Figures 7 to 8B. Preferably, the housing 12 is of cylindrical shape. It is arranged to receive the clamping head 13, the diameter of which is adjusted to take place in the housing 12. The head 13 comprises an insertion sleeve 131 in the housing 12 and a flange

13 to bear on the free end of the sectors 11 delimiting the housing 12. The sleeve 131 has an external cylindrical surface of diameter equal to the internal diameter of the housing 12 delimited by the internal walls of the sectors 11, in order to guarantee a fitting without play from the head 131 into the body 1 of the pliers.

As shown in Figure 2, the housing 12 has a bottom groove 121 at the center of which is formed a plate or pad 14. In addition, the head 13 comprises, as shown in Figure 8B a collar 131c end of the sleeve 131, said flange 131c being intended to be inserted without play in said groove 121 of the housing 12 and delimiting a reservation 131 r of complementary shape of the stud 14 such that said stud 14 enters said reservation during the fitting the sleeve 131 into the housing 12. Thus, the head 13 is perfectly wedged in position in the housing by a double male-female embedding of its sleeve collar 131 in the groove 121 of the housing and the stud

14 of the accommodation in the sleeve reservation 131 r.

Thus, the head 13 is shaped and dimensioned so as to also bear in the bottom of the housing 12 and against the edges of sectors 11 and it is interchangeable, therefore removable from the body 1 of the clamp since it can be simply inserted or removed from the housing 12. However, in order to guarantee the holding of the head in use of the clamp, the latter is anchored in use to the body 1 by means of radial screws 6 inserted in holes provided for this purpose in the sectors 11 and head 13. The clamping head 13 has several movable jaws 130, in practice as many jaws 130 as the clamp has sectors 11, each jaw 130 being associated integrally with a sector 11 by the screws 6. Preferably, there are two screw 6 by sector torque 11 / jaws 130.

The clamp also includes a thrust pin 3 slidingly mounted inside the body 1, along the longitudinal axis. As will be understood hereinafter, the thrust axis 3 is arranged to slide in the direction of the second end 1b of the body 1 under the effect of an external, pneumatic, hydraulic, or even mechanical driving force, depending on the tool on which the clamp is intended to be mounted.

The thrust axis 3 ends with a conical thrust head 32 defining an inclined bearing surface 3a at an angle b relative to the longitudinal direction of the clamp. This conical bearing surface 3a cooperates with a complementary conical bearing surface of the jaws 11 so that an axial thrust of the thrust axis 3 in the direction of the housing 12 under the action of a driving force induces a separation of the sectors 11 by sliding of the conical head 32 on the complementary conical bearing of the sectors 11.

The thrust axis 3 is also movable towards the first end 1a of the body 1, under the effect of a helical spring 7, disposed in an axial housing 36 in the conical head 32 of the axis of thrust 3 and which comes to bear in a reservation provided for this purpose in the bottom of the stud 14 at the bottom of the housing 12. The thrust axis 3 can slide between two extreme positions defined by stops, that the skilled person can realize according to his knowledge. The spring 7 is adapted as a function of the tool on which the clamp is to be mounted, so that its force is less than the external driving force which the tool can exert. Thus, the thrust axis 3 is capable of sliding between:

- a first extreme position when it is not subjected to an external driving force, and

- a second extreme position when subjected to an external driving force. In order to receive the external motive force, the thrust axis 3 is integral through the oblong openings 8 of the body 1 of thrust lugs 4 which extend projecting outside the body 1. Said lugs 4 are fixed on the thrust axis 3 on flats 35 formed in the head 32 of the thrust axis 3.

In a preferred embodiment, there are three lugs 4 are fixed on the thrust axis 3 on flats 35 formed in the head of the thrust axis 3. For this purpose, the lugs 4 each include a screwing lug 41 comprising an orifice 43 through which a screw 5 is screwed into a complementary orifice 33 of the thrust axis 3 and a tooth 42 integral with said screwing lug 41 and having an inclined external support plane of an angle a with respect to a flat common base of the screw tab 41 and the tooth 42.

According to the invention, said lugs 4 are further fixed in longitudinal and radial position on the thrust axis 4 by a fitting means such as a pin 9 driven into a blind hole 44 formed in said lugs 4 and adapted to fit into a hole 34 of corresponding diameter in the thrust axis 3. Preferably, said blind hole 44 for driving out the pin 9 is drilled in tooth 42 along an axis parallel to that of the hole 43 for screwing the tab 41 of the pins 4.

Preferably, the embedding orifices 34 and the screwing holes 33 of said lugs 4 are pierced parallel to one another from the external surface of said flats 35 and open into an internal cavity of the thrust axis 3, cavity comprising in particular an axial tube of the thrust axis 3 communicating with the housing 35 for fitting the spring 7, as visible in FIGS. 4 and 5.

This mounting of the lugs 4 in a fixed position on the thrust axis by means of a pin 9 and of screw 5 provides a significant improvement and reliability of the clamp in that this guarantees an exact position over time. lugs 4 at a distance d relative to the support flange of the sectors 11 as shown in FIG. 2. In this way, an invariant positioning of the lugs 4 is guaranteed over time, even in the event of disassembly / reassembly of the clamp. One obtains among other things thanks to this permanent mounting reference, without play, a precision on the machined parts held using the pliers of the invention of the order of a hundredth of a millimeter, while the anterior pliers provide at best an accuracy of 5 hundredths or more.

Conventionally in itself, the pins 4 allow to cooperate with a cylindrical pin in which the clamp is in practice mounted in use. Such a spindle comprises a movable bushing capable of advancing towards the second end 1b of the clamp under the action of a hydraulic, pneumatic or mechanical driving force transmitted by the machine tool. This socket has at its inner wall, at least one contact zone intended to cooperate with each lug 4 of the clamp. This contact zone can be straight or, advantageously, also conical, so that the contact between the zone and the pins 4 under the action of the driving force, induces a result tending to move the thrust axis 3 in its second extreme position, via each of the pins with conical teeth.

The two extreme positions of the thrust axis 3 are defined so that:

when the thrust axis 3 is in its first extreme position, it does not cooperate with the conical part of the sectors 11 of the second end 1 b defining a first external diameter,

- when the thrust axis 3 is in its second extreme position, its head 3a presses in the conical part of the inner wall of the sectors 11 of the second end 1b so that these deviate to define a second outer diameter greater than the first.

Naturally, the head 13 is arranged so as not to hinder the movements of the thrust axis 3. The stops can be determined by the cooperation between the lugs 4 and the body 1, on either side of the openings 8. Thus, thanks to the connection between the sectors 11 and the jaws 130 of the clamping head 13, it is therefore possible, when the thrust axis 3 is in its first extreme position, to insert the clamping head 13 to the inside a piece to be clamped, the head 13 having been dimensioned in a suitable manner. Then, by bringing the thrust axis 3 into its second extreme position, under the effect of an external driving force, the clamping head 13 clamps the part from the inside. When the driving force for actuating the thrust axis is stopped, it returns back under the return force of the spring 7 and the sectors 11 of the clamp and jaws 130 of the head 13 resiliently return to their rest position . It is therefore possible to remove the part from the clamping head 13.

The clamp according to the invention therefore allows very simply to change the clamping head to perform various tasks. In addition, it adapts to a standard machine, without having to modify or adapt the spindle. It is even possible to change the head without having to remove the clamp from the tool. The saving of time, in particular in adjustment and calibration of the tool is therefore considerable. Such pliers therefore offer great precision and very good rigidity in gripping the part, while allowing the part to be machined over its entire length, without having to change the machine or modify the grip of the part.

Claims

claims

1. Interchangeable head pliers comprising:

- a body (1) defining a longitudinal axis, comprising a first end (1a) intended to be adjusted in a nut (2) and a second end (1b), free, provided with sectors (11) able to deform elastically , in a radial direction and intended to receive a removable head,

- a thrust axis (3) mounted to slide along said longitudinal axis inside said body (1), in a first direction under the effect of a driving force transmitted through the nut by a kinematic connection means and in a second direction under the effect of a spring member (7),

- a plurality of pins (4) mounted integrally and in a regular angular arrangement on the thrust axis (3) and projecting radially from the surface of said thrust axis through the body (1) of the clamp,

characterized in that said pins (4) are fixedly arranged in the longitudinal and radial position on the thrust axis (4) by a fitting means (9).

2. Pliers according to claim 1, characterized in that said body (1) comprises oblong openings (8) through which the pins (4) extend from the thrust axis (3).

3. Pliers according to one of claims 1 or 2, characterized in that the embedding means is a pin (9) driven into a blind hole (44) formed in said lugs (4) and adapted to fit into an orifice (34) of corresponding diameter in the thrust axis (3).

4. Clamp according to one of claims 1 to 3, characterized in that said sectors define a mounting cradle without play of a clamp head comprising deformable sectors capable of being secured to the sectors of the body (1) of the clamp by screwing.

5. Pliers according to one of claims 1 to 4, characterized in that said pins (4) are fixed on the thrust axis (3) on flats (35) formed in the head of the thrust axis ( 3).

6. Pliers according to one of claims 1 to 5, characterized in that said lugs (4) are locked in rotation on the thrust axis (3) by screwing in an orifice (33) drilled on said thrust axis ( 3)

7. Pliers according to one of claims 3, 5 and 6, characterized in that the embedding (34) and screwing (33) orifices of said lugs (4) are drilled parallel to each other from a external surface of said flats (35) and open into an internal cavity of the thrust axis (3).

8. Pliers according to one of claims 1 to 7, characterized in that said lugs (4) comprise a screw tab (41) comprising an orifice (43) through which it is screwed on the thrust axis (3) and a tooth (42) integral with said screw tab (41) and having an external support plane inclined at an angle (a) relative to a common base of the screw tab (41) and the tooth (42).

9. Pliers according to claims 3 and 8, characterized in that said blind orifice (44) for driving out the pin 9 is drilled in the tooth (42) along an axis parallel to that of the orifice (43) for screwing .

10. Clamp according to one of claims 4 to 9, characterized in that the cradle for mounting the removable head delimited by the sectors of the body has an internal planar guide surface and the removable head a sleeve for mounting the planar external surface and of diameter equal to the internal diameter of the mounting cradle.

11. Machining device comprising a pliers with interchangeable head according to one of claims 1 to 10