Abstract:
The clamping assembly includes a cutting insert with a lower passage housing a screw with a head for clamping the cutting insert against a bearing surface provided on a tool holder and comprising a screwing hole, wherein the screw head is shaped and arranged so as to press only on one side, with a flared opening, of the screw hole, the passage has a template incompatible with a template of the head in the clamping position, and, outside of the clamping, the cutting insert and the screw can change mutually relative positions so as to harmonize the two templates and thus release the cutting insert without having to entirely unscrew the screw.

Description:
FIELD OF THE INVENTION 
     This invention relates to the clamping of a cutting insert on a bearing surface provided on a tool holder. 
     DESCRIPTION OF RELATED ART 
     Conventionally, a milling cutter comprises a housing with a threaded hole in the base surface, receiving a screw passing through a smooth-sided passage extending in the thickness direction of the cutting insert. As the fit must be relatively strong in order to resist the vibrations which would cause an unscrewing, the hole is relatively deep and has a relatively small thread step so as to have a thread slope that is also very small. In this way, the matching surfaces of the screw threads and of the hole are almost turned in an axial direction, so that any parasitic axial force is exerted substantially perpendicularly on the threads and, as the wedge effect is thus minimal, the screw does not have a tendency to become unscrewed. 
     Therefore, each time the cutting insert is changed, the user must carry out a large number of unscrewing rotations, in order to release the worn-out cutting insert, by totally unscrewing the screw, and then carrying out the reverse operation. This involves a loss of time, and, in addition, there is a risk that the user will incorrectly position the cutting insert or the screw, which generally leads to the destruction of the cutting insert and sometimes of the tool holder. 
     The applicant has also identified two other problems, said problems being heat-related. These two problems are associated with maintaining the clamping by the screw, due to the fact that, in use, the heating of the cutting insert clearly expands the screw, which is made of steel, more than it expands the cutting insert, which is made of carbide. A first heat-related problem is associated with the fact that the head of the screw moves up, by an axial expansion with respect to its body held in the hole, and this can affect the contact of the cutting insert against the base surface of the housing. The applicant has also identified a second heat-related problem by observing that, in the subsequent cooling, the screw returned to a position corresponding to a slight additional screwing, and that the increase in pressure, by the conical under-portion of the screw head on the periphery of the hole having the same shape, would cause, over the course of such repeated heat cycles, a cracking of the cutting insert, starting from the hole moving out in a radial direction. 
     This invention is intended to provide a solution, or to at least attenuate the disadvantages related to at least one of the three problems mentioned above. 
     SUMMARY OF THE INVENTION 
     To this end, the present invention relates first to a clamping assembly comprising a cutting insert and a device for clamping the cutting insert on a bearing surface provided on a tool holder. The device for clamping the cutting insert comprises a slide including a guide segment intended to be slidably mounted in a guide hole provided in the bearing surface, and a clamping segment including a clamping head comprising a lateral clamping relief with a shape arranged for having a clamping contact surface, at least partially turned toward the guide segment, so as to abut an opposite seat surface, associated with a cavity in the cutting insert, leading to at least one bearing face of the cutting insert, and arranged so as to house the clamping segment, so as to clamp the cutting insert against the bearing surface when the cutting insert and the slide are mutually arranged in a mutually relative clamping position. The clamping assembly is characterized by the fact that the cavity of the cutting insert has a passage template, along an access passage for the head from the bearing face to the seat surface, the seat surface being associated exclusively with one side of the cavity, wherein the passage template varies according to a suitable shape, with respect to a bulk template of the lateral clamping relief, so that the passage template is incompatible with the bulk template when the cutting insert and the slide are arranged in said mutually relative clamping position, and said suitable shape being so that the passage template is compatible with the bulk template when the cutting insert and the slide are arranged in at least one other mutually relative position, for releasing the cutting insert. 
     Thus, when the cutting insert is clamped against the bearing surface in a fitted position determined by said relative position, and the head of the slide is therefore held in the cavity of the cutting insert, it is in fact the bearing surface that maintains the desired relative position. Indeed, the cutting insert has, with the bearing surface, a certain coefficient of friction and/or is adapted to a lateral wall limiting a housing. For clamping, the single bearing contact exerted on said side of the cavity is therefore sufficient. Any side surface of the cavity, laterally opposite the seat surface, remains totally free, and the same is true of any side surface of the clamping head, opposite the lateral clamping relief. Therefore, the cutting insert is simply pinched between the jaws constituted by the lateral clamping relief and the base surface of the housing, i.e. it is subjected only to a pressure stress. The through hole of the cutting insert is therefore not subjected to tearing stresses, which would crack the wall thereof. 
     When the slide is forced to move up so as to unclamp the cutting insert, the cutting insert is therefore released from the bearing surface and can thus change its relative position with respect to the slide, so as to adopt the release position, releasing the head of the slide and thus releasing the cutting insert. Depending on the embodiment, one of the two elements, either the cutting insert or the slide, automatically adopts the desired relative orientation with respect to the other for automatic detachment, or the user intervenes. In every case, it is therefore unnecessary to totally disassemble the slide from the tool. 
     The cavity can also lead to an upper face, opposite the bearing face, so as to provide an upper passage, for access to the clamping head by a screwdriver or a maneuvering key, if the clamping head also constitutes a driving head. Depending on the case, the upper passage makes it possible to pass the guide segment, for a classic assembly operation. The cavity can in particular be functionally symmetrical so that the cutting insert is top-bottom reversible. 
     In a specific embodiment, the passage template and the bulk template are arranged so that said other mutually relative position is reached by tilting the cutting insert with respect to the slide. 
     There is therefore a relative tilting, i.e. the cutting insert can tilt with respect to the bearing surface, and the slide can then keep, in the raised unclamping position, the orientation that it had in the clamping position, or the cutting insert can keep its orientation parallel to the bearing surface, and then the slide, when it partially moves up out of the guide hole, rotates, like a screw, about a geometric axis, so as to release its lateral clamping relief with respect to the clamping contact surface, by said rotation of a certain angle. Alternatively, the guide hole and the slide may extend in an arc of a circle, so that the overall orientation of the slide tilts when it rises, and thus the lateral clamping relief can be arranged so that it tilts in such a way that it tends to be aligned with the direction of extension of the passage, so as to become compatible with it. 
     In another embodiment, the passage template and the bulk template are arranged so that said other mutually relative position is achieved by a relative rotation of the cutting insert, with respect to the slide, in a plane substantially parallel to the bearing surface. 
     The lateral relief of the head therefore has a non-circular bulk template, from a top view parallel to the bearing surface, and the aforementioned rotation of the cutting insert suppresses its registration with the bearing surface, so as to establish another fit, in which the bulk template is compatible with the passage template. 
     In such a case, a lateral relief for driving the slide, and a complementary relief of the tool holder can be arranged so that, by a partial lifting of the slide by at least a height determined with respect to the guide hole, the slide pivots over itself by a certain angle that brings the bulk template to an orientation making it compatible with the passage template. 
     In such a case, the slide has a rectilinear guide segment, for example of the screw type, so as to be capable of rotating axially. 
     In yet another embodiment, the passage template and the bulk template are arranged so that said release position is reached by a movement of the cutting insert with respect to the slide, in a plane parallel to the bearing surface. 
     The passage therefore comprises, opposite a side comprising the seat surface, a recess for housing the head, so that a radial backward movement of the seat surface is then possible, over a sufficient distance to move out of the grip, i.e. the overhang, of the lateral relief bearing the clamping contact surface. As the “attachment”, or bearing, of the clamping contact surface on the seat surface is thus suppressed, it is easy to design the passage template in order to allow the head to exit and, of course, to put in place a new cutting insert which is similarly oriented. 
     It is possible in particular to consider such a passage, which would be bent, comprising a “vertical” opening segment leading to a cavity in the shape of a “horizontal” tunnel at a certain level in the thickness of the cutting insert. Once mounted in the cavity, by an axial movement in the opening segment, the head of the slide can be pushed back laterally towards an end wall of the tunnel, due to the fact that the opening segment comprises a narrow lateral slot, allowing the passage, by a radial movement, of a neck bearing the head, but preventing any downward return of the head. The horizontal tunnel and the slot located below thus have a general dovetail cross-section, with the horizontal tunnel having a lower edge constituting an internal track of said seat, receiving the bottom of the head of the slide. 
     The guide hole can generally have an oblique direction of extension with respect to a normal to the bearing surface, with the clamping segment capable of having the same orientation or a different one. 
     In order to distribute the load, the seat surface preferably extends over a partial peripheral arc of the passage of the cavity, not exceeding 180 degrees so as to give the clamping head an unlimited freedom to bend. The blocking bearing on such an arc can be provided on a single area or can be distributed over a plurality of separate areas, for example two bearing areas mutually offset by 90 degrees so as to best secure the cutting insert in the corresponding directions. However, if the cutting insert comprises a plurality of cutting edges and can therefore be mounted according to a plurality of azimuthal orientations, the seat surface can be provided in a same plurality of distributed sectors, or the seat surface can even constitute a track surrounding the entire cavity, with the understanding that, according to the invention, only a single sector is functional for each position offered. In consideration of the fact that, according to the invention, there is no need to have a counter-bracing area on the cutting insert, which would be laterally opposite the seat surface and would have a specific shape for this purpose, it is therefore possible for such an opposing area, functionally free when the cutting insert is clamped in a given azimuthal position, to have a shape that serves as a seat surface when the cutting insert is mounted according to another azimuthal orientation. 
     The passage template can thus be arranged so that the head is released by moving, according to a relative movement, the clamping contact surface toward a side opposite said arc, so that the clamping contact surface no longer overhangs the seat surface, which holds the head, said relative movement being a radial movement with respect to the passage or being a relative tilting of the cutting insert, wherein the respective templates are then compatible. 
     In an advantageous embodiment, the guide hole is formed in an oblique direction of extension toward an extension area of a lateral wall limiting the bearing surface. 
     The cutting insert can thus be clamped between, on the one hand, a stationary edge line defined by the bottom of the lateral wall thus defining a housing and, on the other hand, the clamping contact surface belonging to the slide, which therefore constitutes a jaw opposite the stationary edge. As the plane of the lateral wall and the direction of extension of the guide hole form a V shape, a slight unclamping of the cutting insert enables it to move up on a branch of the V shape defined by the slide, so that the cutting insert, thus released from the contact with the lateral wall, can thus adopt the desired orientation so as to be released, by a movement, by a rotation or by tilting. It is to be noted that the aforementioned V-shape does not involve the base of the housing, i.e. it is possible for the plane of the lateral wall to be inclined on a normal to the base, or bottom, of the housing, with the direction of extension of the through-hole being oblique or being parallel to such a normal to the base. 
     In such a case, the lateral wall can extend in a generally oblique, flared manner with respect to a normal to the bearing surface. 
     The lateral wall can have a rectilinear, or curved or even layered rising profile. 
     In a specific embodiment, the guide hole and the slide extend in an arc of a circle. 
     Insofar as the guide hole and the slide have mutually adjusted transverse cross-sections, the slide has exclusively a sliding movement with a tilting of its general orientation, which tilting can be performed according to an angle allowing for the desired adaptation between the two associated templates. 
     The passage template can comprise a constriction segment. The passage can thus, for example, comprise two opposite conical opening, or mouth, segments, opening outward, and the seat surface is located on one of the conical surfaces constituting slopes of the constriction, or, even, the seat surface is provided twice, by providing two said surfaces on two respective slopes, if the cutting insert is reversible. 
     The guide segment can comprise drive control means, i.e. for maneuvering the slide. 
     Said drive control means can, for example, be an end portion, slotted or sided, of a screw constituting the slide, which end portion is opposite the head; i.e. the guide hole is a through-hole, for an axial or a lateral access to the drive control end portion. 
     The guide segment advantageously comprises a lateral relief, for locking the slide in the clamping position, said lateral relief being arranged so as to cooperate with a complementary relief of the tool holder. 
     Such a lateral relief can easily be coupled to a drive gear for driving an axial relief of the slide. 
     The lateral relief for locking the slide in the clamping position is, for example, a lateral notch arranged to receive an end portion, for maneuvering control and position locking, of a maneuvering screw mounted in a threaded hole and arranged to push the slide into the guide hole, by pushing a flank of the notch. 
     The maneuvering screw can have an inclined direction of extension with respect to a direction of extension of the through-hole; however, this condition is not necessary insofar as, in use, the slide does not need to entirely leave the guide hole. It is therefore possible for the threaded hole, for the maneuvering screw, to have an axis parallel to the direction of extension of the guide hole for the slide. For example, the maneuvering screw can have an end segment, in principle smooth, separated from the rest of the screw by a diametrically extending, or annular, groove or by a simple lateral notch, the slide having the same type of shape so that its end segment can be housed in the groove of the screw, while the end segment of the maneuvering screw is itself housed in the groove of the slide. In other words, and more generally, the maneuvering screw may be thought of as a rack engaged with a lateral relief of the slide. To allow the maneuver, the guide segment of the slide is axially smooth, i.e. it does not engage with the wall of the guide hole. The slide and the screw are thus laterally coupled in opposite orientations, head-to-tail; the maneuvering screw thus may be thought of as a kind of a serrated wheel engaged with one flank or another of the notch, or engaged with an entire segment of the slide threaded for this purpose, with the threads of said slide thus providing a plurality of such notches. 
     The clamping contact surface and the seat surface are advantageously two respective ramps provided for a mutual sliding during the sliding of the slide entering the guide hole, so that a free segment of the slide, bearing the clamping head, is bent back and received in a lateral recess of the cavity, provided for this purpose on a side opposite to the seat surface. 
     The cavity advantageously forms, with the lateral recess, a housing having a width of at least 1.25 times, preferably 1.5 times, and more preferably 2 times, a width value of the clamping head. 
     Advantageously, to ensure a substantially constant clamping force when the cutting insert is heated by friction on a working piece being machined, the clamping contact surface and the seat surface forming a ramp are oriented, in the clamping position, in a direction cutting a virtual longitudinal axis of the slide at an axial point located substantially in a virtual radial surface of the apex of the guide segment, bearing the clamping head. 
     As the guide segment is locked in the guide hole, the natural isotropic extension of the clamping head occurs according to a similar transformation originating at said axial point. The two ramps are therefore aligned with the local direction of volume extension, so that they slide over each other without tending to separate or press on one another excessively. 
     The invention also relates to a cutting insert for a clamping assembly according to the invention, comprising a seat surface, arranged to receive a clamping contact surface of a slide. The clamping contact surface may be associated with a cavity leading to at least one bearing face of the cutting insert and arranged so as to house a head segment, for clamping the cutting insert, belonging to the slide, characterized by the fact that the cavity of the cutting insert has a passage template, along an access passage for the head from the bearing face to the seat surface. The seat surface may be arranged so that, in use, it is associated exclusively with a single side of the cavity, with the passage template varying according to an adapted shape so as to enable the clamping contact surface of the slide to move away from the bearing surface and thus to release the slide. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention can be better understood from the following description of an embodiment of a tool holder with a cutting insert clamping device according to the invention, in reference to the appended drawing, in which: 
         FIG. 1  is a partial perspective view of a milling cutter which provides a tool holder according to the invention and a plurality of housings for cutting inserts, 
         FIG. 2  is a cross-section view along the thickness direction of one of the housings, showing a cutting insert held in a clamping position by a clamping screw, 
         FIG. 3  is similar to  FIG. 2 , with the cutting insert shown unclamped, and 
         FIGS. 4A ,  4 B and  5  show schematically an alternative in which the slide has no drive thread,  FIG. 4A  showing the cutting insert from a bottom view, with its hole, and in  FIG. 4B  the slide is shown in perspective, and  FIG. 5  showing an axial cross-section view of the passage of the cutting insert. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a portion of a milling cutter  20  with a general rotation axis  21  in the shape of a crown, in this case seen obliquely from behind, comprising, at a top end, a plurality of teeth each having a housing  30  with a substantially planar base surface  32  extending in a substantially axial and radial plane with respect to the general axis  21 . Each base surface  32  serves as a bearing surface for a lower main face  2  of a cutting insert  10  opposite to a substantially parallel upper main face  1 . The main faces  1  and  2  are connected by a plurality, in this case five, of lateral flank surfaces, in this case identical, such as, for example, the lateral flank surface  19 , defining, with at least one of the main faces  1  and  2 , the same number of cutting edges, which can be used successively. 
       FIG. 2  is a view according to a cross-section of one of the housings  30 , in a radial plane of the cutter  20 , showing the corresponding cutting insert  10  and an associated clamping slide, which in this case is a clamping screw  50  with a geometric axis  51 , housed in a threaded guide hole  40  formed in the base surface  32  and with a geometric guide axis  41 , in this case merging with the screw axis  51 . 
     The clamping screw  50  comprises, in succession, (a) a clamping head  52 , in this case a cylindrical one having with a lateral peripheral clamping relief  52 R, with an apex surface  53  comprising a diametral maneuvering slot  54 , then (b) a neck  52 C forming a groove constituted by an upper flank  55  forming a substantially frusto-conical bottom of the peripheral relief  52 R, a cylindrical groove base segment  56  and a lower, substantially frusto-conical, flank  57 , and finally (c) a guide body segment  58 , with a thread  58 F. The clamping screw  50  is housed in the guide hole  40  and engaged with a thread  40 T thereof. The lower flank  57  is symmetrical with the upper flank  55  with respect to a median plane located at a half-thickness level of the cutting insert  10 , so as to be capable also of mounting the cutting insert  10  in an overturned position. The lower flank  57  is not functional in the position shown; i.e., for a cutting insert  10  which would not be reversible, the lower flank  57  could be replaced by a conical segment, according to an angle of any value and sign, or by a non-conical segment, serving to superelevate the clamping head  52 . 
     For the simplicity of the description below, the guide segment  58  is considered to be constituted by two threaded segments, namely a, lower, free end segment  58 E, opposite to an upper segment  58 T limited by an upper virtual radial plane  58 P constituting the limit with the neck  52 C and comprising an axial point  58 A, located on the screw axis  51 . 
     Reference  58 G designates, on the threaded surface  58 F, an apex thread, in the upper axial position, of the upper segment  58 T, having an upper flank  58 S, i.e. turned somewhat toward the clamping head  52 , and a lower flank  58 I, turned somewhat toward the free end segment  58 E. References  59 G,  59 S and  59 I similarly, but generally, designate threads, not all shown, of the free end segment  58 E and two flanks, upper and lower, respectively, thereof. The threads  59 G however occupy any axial position on the free end segment  58 E. Cooperating with the threads  58 G and  59 G, respectively, the thread  40 T similarly comprises an apex helical groove  48  and helical grooves  49 , with respective upper flanks  48 S and  49 S, turned somewhat away from the housing  30 , and respective lower flanks  48 I,  49 I axially opposite the associated upper flank  48 S,  49 S. 
     In this example, the guide axis  41  extends obliquely, in this case by around  10  degrees, with respect to a normal to the base surface  32 . The base surface  32  is, in this case, associated with a lateral wall  33 , in this case perpendicular to the base surface  32 , for a more precise and more stable fixing in the desired position for the cutting insert  10  on the base surface  32 . The guide hole  40  descends in an oblique direction toward a region of extension of the lateral wall  33 , thus forming a V shape with said lateral wall  33 . 
     As shown in  FIG. 1 , the guide axis  41  extends substantially in a circumferential direction with respect to the general axis  21 , the clamping head  52  being somewhat turned away from the general axis  21 , i.e. somewhat toward the opening of a groove between two of the teeth, which groove is therefore open radially toward the outside, limited by a front surface of the tooth in question, i.e. limited by the upper main face  1  (or the base surface  32 ), and by the back surface of a preceding tooth, with the rotation occurring in the clockwise direction. In this way, the extension of the guide axis  41  is better offset from the back portion of the preceding tooth, so that a screwdriver can easily access the maneuvering slot  54 . The chamfer also has a groove, or notch, having the shape of a cylinder portion along the guide axis  41 , serving as a cradle for the screwdriver. 
     The cutting insert  10  comprises a cavity  12  forming a passage  12 P having a geometric passage axis  11 , in this case substantially perpendicular to extension planes of the main faces  1  and  2 , the passage  12 P, in this case, mutually connecting the upper and lower main faces  1  and  2 , and leading to a central area thereof. The passage  12 P, in this case, has a shape according to a passage template  12 G of the same type as a bulk template  52 G presented by the clamping head  52  together with the upper flank  55 , i.e. an upper opening, segment with a substantially frusto-conical upper flank wall  15 , then an intermediate constriction segment, with a substantially cylindrical wall  16 , and a lower opening, or mouth, segment, with a substantially frusto-conical lower flank wall  17 . The term “template” thus designates the shape and the size of a transverse cross-section of the passage  12 P as well as of the clamping screw  50 , and also designates the change of these shapes and sizes along the corresponding axis  11  or  51 , and also in consideration of the relative position imposed between these two elements, depending in particular on the inclination and the mutual positions between these axes. 
     As shown in  FIG. 2 , the passage  12 P is located in the cutting insert  10 , so that when the lateral flank surface  19 , for example, is in contact with the lateral wall  33 , the upper flank wall  15 , partially turned toward the upper opening, constitutes a lateral abutment relief preventing the clamping head  52  from penetrating further into the hole  40 , so as to thus clamp the cutting insert  10 . Specifically, a seat surface  15 A, belonging to the upper flank wall  15  and located beside the lateral wall  33 , serves as a seat for a clamping contact area  55 A belonging to the upper flank  55 , of the clamping screw  50 , partially turned toward the body segment  58 . The base surface  32  and the lateral wall  33  thus delimit a corner edge line which, with regard to the left half of the cutting insert  10 , is substantially diagonally opposite the clamping contact area  55 A which is capable of moving toward the base surface  32 . The clamping contact area  55 A represents an area of current contact when the clamping screw  50  rotates, i.e. the other part of the upper flank  55  constitutes a plurality of such clamping contact areas, which are “eligible” in mutually exclusive manner, i.e. which will, during the screwing, successively replace the current clamping contact area  55 A. The clamping of the cutting insert  10  is thus ensured, with the threaded surface  58 F and the threaded surface  40 T serving to guide the clamping screw  50  and, by friction with the thread  58 F, to hold the cutting insert  10  in the clamped position. 
     It should be noted that, if the guide axis  41  were perpendicular to the base surface  32 , i.e. if the screw head  52  did not move laterally, by the screwing, toward the seat surface  15 A, in this case to the left, the cutting insert  10  should therefore occupy, from the beginning of the screwing, a laterally offset position toward the seat surface  15 A, so that the entire periphery of the upper flank  55  does not abut, during the screwing, the entire periphery of the upper flank wall  15 . The passage axis  11  should then, in the functional position of the cutting insert  10 , occupy a laterally offset position with respect to the guide axis  41 , as shown by  FIG. 2  in the case of oblique axes. 
       FIG. 2  shows that, on the side opposite the seat surface  15 A, therefore, in this case, to the right, the cavity  12  provides a significant radial clearance with respect to the clamping head  52 . This means that, with respect to the cavity volume reserved for the clamping head  52  when it is in a light contact and clamping position on the seat surface  15 A, without any bending constraint of the clamping head  52 , the cavity  12  comprises a recess  12 E located radially opposite the seat surface  15 A, and therefore also opposite the clamping contact area  55 A, so as to provide a bending volume for bending the clamping head  52  when it comes down onto the seat surface  15 A. 
     In the case of a lateral wall  33 , which, in a top view of the housing  30 , would have not one but two mutually inclined lateral faces delimiting a vertical corner edge of the base surface  32 , in order to better fit the cutting insert  10 , the guide axis  41  would preferably be directed downward substantially toward an extension of this vertical edge, so as to have clamping force components toward the two lateral surfaces. 
     Alternatively, the cavity  12  is in the oblique direction of extension with respect to a normal to the lower main bearing face  2 , with the passage axis  11  merging, for example, with the guide axis  41 . In a similar case, the passage template  12 G can be distorted with respect to this embodiment so that the seat surface  15 A forms a frusto-conical band entirely surrounding the cavity  12 . 
       FIG. 3  shows the unclamped position of the cutting insert  10 . The clamping screw  50  has been partially unscrewed from the guide hole  40 , over a given length, so that the cutting insert  10  can be manually lifted by the same length. This lifting of the clamping head  52 , along the oblique branch of the V shape represented by the guide axis  41 , therefore separates the clamping head  52  from the lateral wall  33 , and this loosening of the upper flank  55  makes it possible to totally free the upper flank  55 , i.e. also free the seat surface  15 A corresponding to the clamping position. In the manual lifting of the cutting insert  10  accompanying the clamping screw  50 , for example by maintaining a lateral rest contact on the lateral wall  33 , the clamping contact of the cutting insert  10  with the clamping contact area  55 A slides from the seat surface  15 A toward the cylindrical wall  16  constituting a constriction of the passage  12 P. When, with respect to the lateral wall  33 , the upper flank  55  is separated by at least a distance existing between the left edge of the cylindrical wall  16  and the lateral wall  19 , in contact with the lateral wall  33 , the cutting insert  10  can therefore continue its upward sliding movement on the lateral wall  33 , and thus be totally disengaged, since the upper flank  55  no longer overhangs at all the upper flank wall  15  comprising the seat surface  15 A. 
     As shown in  FIG. 3 , the passage template is such that the right, inactive, edge of the cylindrical wall segment  16  is sufficiently separated from the left, active, edge, that the right edge of the apex surface  53  of the clamping head  52  is located inside the passage template thus defined, and therefore allows for the desired release. Indeed, as the clamping head  52  is in this case cylindrical, therefore with a rectangular axial cross-section, and with a screw axis  51  inclined on the passage axis  11 , the clamping head  52 , thus arranged crosswise, tilted, has, with respect to a rising movement, in this case vertical, of the cutting insert  10 , a bulk template  52 G greater than that corresponding to a circle according to its diameter, which template  52 G in this case substantially reaches the value of a diagonal of the aforementioned rectangle. However, to limit the width necessary for the cylindrical wall segment  16 , the cutting insert  10  can be caused to tilt so as to orient the passage axis  11  substantially according to the axis  51 . This tilting is possible as soon as the cutting insert  10  is, as shown, almost outside of the housing  30 , since there is then a clearance with respect to the clamping screw  50 . Alternatively, it is possible for the lateral wall  33  to be not perpendicular at the base  32 , but flared so as to allow for such a pivoting movement. 
     As shown in the drawing, the cavity  12  is not, in this case, a blind hole but is also open at the upper main face  1  so that a maneuvering screwdriver can access the maneuvering slot  54  of the clamping screw  50  by an upper passage, which even allows for the passage of the clamping head  52 . In fact, as shown, the passage axis  11  passes through a center area of the upper  1  and lower  2  main faces, and the cavity  12  has a symmetrical shape with respect to said median plane, so that the cutting insert  10  is reversible and thus provides ten cutting edges, since the so-called upper main face  1  can become a bearing face and thereby cutting edges limiting the lower face  2  can be used for cutting operations. 
     Preferably, as in this case, the upper flank  55  is only partially turned toward the guide segment  58  to thus form a ramp suitable for sliding on the seat surface  15 A, axially opposite the direction of movement, according to the axes  41 ,  51 , of the clamping screw  50 , and the clamping screw  50  is elastically flexible so as to thus, as it goes down in the passage  12 P, store potential bending energy provided in reaction, by a wedge effect, by the seat surface  15 A forming a ramp. As the clamping screw  50  bends towards the side opposite that comprising the clamping contact area  55 A, and as this opposite side is, according to the invention, non-functional with regard to the clamping, it is therefore easy to design the complementary side of the cavity  12 , laterally opposite the seat surface  15 A, at a relatively long distance from the non-functional side of the clamping screw  50 , to thus leave a large lateral space for the aforementioned bending of the clamping head  52  and the neck  52 C, overhanging the guide hole  40 . In consideration of this possibility of obtaining a significant bend in the neck  52 C, the clamping screw  50  can be chosen from more flexible material than in the prior art, so that, even if the clamping screw  50  is pressed down with a force slightly lower or greater than that specified, it will still perform its clamping function, without respectively a risk of loosening or a risk of transmitting excessive stress to the cutting insert  10  and to the milling cutter  20  that could damage them. 
     Thus, the clamping contact surface  55 A and the seat surface  15 A are each two ramps provided for mutual sliding during the sliding of the clamping screw  50  entering the guide hole  40 , so that the neck  52 C is bent back and thus the clamping head  52  is received in the lateral recess  12 E of the cavity  12 , provided for this purpose on the side opposite the seat surface  15 A. 
     The cavity  12  forms, with the lateral recess  12 E, a housing having a width at least 1.25 times, preferably 1.5 times and, even more preferably 2 times the width of the clamping head  52 . 
       FIGS. 4A ,  4 B and  5  show schematically an alternative in which the slide does not have a drive thread. The functional elements similar to the functional elements of  FIGS. 1-3  have the same references numerals, preceded by the hundred digit “1xx”. The cutting insert  110  is seen from below in  FIG. 4A , from its lower surface  102 , having a head passage  112 PT and a neck passage  112 PC, leading to a cavity  112  at an intermediate level in its thickness direction.  FIG. 5  is an axial cross-section view according to the head passage  112 PT. 
     The overall passage is therefore double, with the head passage  112 PT, with a template  112 GT, for passing the clamping head  152  and optionally then for housing the neck  152 C, said template  112 GT being associated with a neck passage template  112 GC, for passing the neck  152 C. For the simplicity of the description, the head passage template  112 GT is in this case rectangular, with sides of respective sizes having respective values 1 and e. The neck passage  112 PC corresponds to a slotted flare formed in a limited periphery are of the head passage  112 PT. 
     The clamping head  152  of the slide  150 , in the shape of a rectangular parallelepiped, having a length L, a width l and a thickness e, can therefore pass through the head passage  112 PT only by having the desired orientation according to three directions of spatial orientation, i.e. with its sides of length L aligned according to a passage axis  111  (thus fixing 2 degrees of rotational freedom), so that one of the small faces, namely end surfaces, of size l×e, having a bulk template compatible with the head template  112 GT, can be disposed in front of the passage  112 PT. A final rotation (third degree of rotational freedom) about a direction parallel to the passage axis  111  makes it possible to properly fit the clamping head  152  in front of the head passage  112 PT, and the neck  152 C in front of the neck passage  112 PC. 
     The neck  152 C is connected obliquely to the clamping head  152 , i.e. starting from the clamping head  152 , the neck  152 C passes through a virtual plane of extension of the one of said end surfaces that will be introduced last, to the right in  FIG. 4A , and the neck  152 C merges with the body  158  of the slide. The neck passage template  112 GC has the desired width and a flare angle, so that the neck  152 C can bring the clamping head  152  into the housing  130  and can cause the clamping head  152  to turn therein in any direction. There can therefore be a final pivoting of the neck  152 C from the left flared edge of the additional passage  112 PC toward, or in, the head passage  112 PT, or there can be a rotation of the neck  152 C and the clamping head  152  about the axis  151  of the neck  152 C. The neck passage  112 PC can also constitute a slot at the actual level of the cavity  112 , so that it can thus radially move the clamping head  152  toward a lateral edge of the cavity  112 , which thus constitutes a tunnel, as mentioned above. 
     The clamping head  152  thus constitutes a sort of swivel joint, with a relative pivoting movement in the cavity  112 , and this pivoting modifies the bulk template  152 GT of the head  152 , with respect to the passage direction  111 , in order to adapt it or not to the head passage template  112 GT and thus release or lock the head  152  and therefore the cutting insert  110 . 
     Of course, the aforementioned rectangular parallelepiped shape of the clamping head  152  is only an example. It is possible in particular to consider a substantially flattened ellipsoid shape having a given size, and to consider a head passage template  112 PT of the same size leading to a spherical cavity, for example, thus enabling the swivel joint to be held by relative rotation about the passage axis  111 . 
     Regarding the parasitic screwing due to the heat cycles, identified by this inventor, an explanation is proposed below, in reference to  FIGS. 1 to 3 . 
     With the clamping screw  50  first being firmly screwed, the upper flanks  58 S,  59 S and others, and the threads  58 G,  59 G and others, are thus in contact with the upper flanks  48 S,  49 S and others, overhanging them, of the grooves  48 ,  49  and others, of the thread  40 T. During the heating, the clamping screw  50  tends in particular to extend, so that the upper flanks  59 S of the threads  59 G of the free end segment  58 E separate from the upper flank  49 S of the opposite groove  49  and move downward, in a purely axial direction, more deeply into the guide hole  40 , until the thread abuts the lower flank  49 I of the corresponding groove. With the axial extension then being blocked by the lower groove flanks  49 I, the purely axial extension force of the clamping screw  50  is exerted increasingly thereon. As the lower flanks  49 I constitute a helical ramp, the free end segment  58 E is thus twisted, i.e. it continues its downward movement, but helically, into the guide hole  40 . The vibrations associated with the operation of the milling cutter  20  can only contribute to the release of the buttressing effect against the lower groove flanks  49 I, so that the threads  59 G of the free end segment  58 E succeed to slide, by jerking with the vibrations, on the opposite lower groove flank  59 I, of the down stop. 
     After stopping the milling cutter  20 , which served as a radiator owing to its relatively large surface area, the milling cutter  20  cools more quickly than the cutting insert  10 , so that the threads  59 G of the free end segment  58 E, at the base of the hole  40 , farthest from the clamping head  52  which was the heat source, tend rapidly to return to their resting shape, i.e. the threads  59 G of the free end segment  58 E contract, in particular axially. In consideration of the fact that the cooling wave is propagated only progressively toward the clamping head  52 , the threads  59 G at various levels of the free end segment  58 E have mutual delays for their return to a nominal axial threading step value. This results in a modulation of the local value of the axial threading step according to the axial position considered, which involves an axial pinching of the thread  40 T. Indeed, the particular threads  59 G that are located at the very end of the free end segment  58 E constitute a jaw which was lifted up near or against the associated upper groove flank  49 S, while the particular threads  59 G of the free end segment  58 E that are closest to the clamping head  52  are still abutting the associated lower groove flank  49 I. 
     The free end segment  58 E, thus pinching a segment of the thread  40 T, therefore does not become unscrewed in order to return to its original position. The upper segment  58 T cannot be a driving member, in this aspect, because the apex thread  58 G (which is theoretically, due to the axial expansion during the heating, the only one that has maintained a contact with the associated upper groove flank  48 S) is in contact only under insufficient pressure with the upper flank  48 S. As, on the one hand, the free end segment  58 E is thus axially anchored more deeply than desired, and, on the other hand, the upper segment  58 T begins to cool, the latter contracts axially. As the upper segment  58 T is borne by the free end segment  58 E, the aforementioned contraction occurs in a downward movement, toward the free end segment  58 E, so that the upper flank  58 S of the apex thread  58 G of the upper segment  58 T temporarily loses its upper contact. This contact, which served to clamp the cutting insert  10 , in the axial direction, also prevented any rotational movement, due to a friction coefficient on the upper thread  48 S. As this upper contact of the upper segment  58 T has disappeared, or was reduced, the upper segment  58 T can return to its resting shape, in a cold condition. As the lower end of the upper segment  58 T is “supported” by, and integral with, an upper “bearing” end of the anchored free end segment  58 E, the upper segment  58 T will therefore return to its resting shape, in a cold condition, due to, simultaneously, the axial contraction and a screwing of an angle equal to that which the upper “bearing” end of the free end segment  58 E initially turned, by expansion. 
     The upper end of the free end segment  58 E is in fact somewhat virtual, because it has a variable axial and possibly changing position, since it involves the axial level where the support contact, or attachment, occurs of the lower flanks  59 I on the lower groove flanks  49 I, and this level is dependent on the change in temperature and, in addition, disparities can occur in the coefficient of friction between the various basic surfaces in contact. Finally, as the anchoring of the free end segment  58 E disappears with its total cooling, its two ends, upper and lower, respectively, can move toward one another, with a slight unscrewing of the lower end and a slight screwing of the upper end, and therefore also a screwing of the clamping head  52 , opposites the axial component of the reaction force of the seat surface  15 A. 
     In short, as the clamping screw  50  progresses along the helical path of the thread  40 T, like a caterpillar, the lower segment ( 58 E) extends and becomes attached to the ground, and then attracts the upper segment ( 58 T). 
     In order to maintain an optimal clamping when the cutting insert  10  increases in temperature, the clamping contact surface  55 A and the seat surface  15 A forming a ramp are oriented, as shown in  FIG. 2 , in the clamping position, in a direction cutting the screw axis  51  at the axial point  58 A of the plane  58 P located at the level of the apex thread  58 G, of the apex of the guide segment  58 . 
     Indeed, as the steel clamping screw  50  expands more than the carbide cutting insert  10 , and as the guide segment  58  is held axially, the radial plane  58 P of the apex thereof is in fact the only one that, under heat, is stationary with respect to the housing  30 . Indeed, as explained above, the guide segment  58  will dilate and move downward into the guide hole  40 , by coming into a support contact, on the thread  40 T, by the upper flank  58 S. It is therefore the apex thread  58 G that determines (the inclination due to the thread twist being neglected) the position of the stationary radial plane  58 P. The external portion of the clamping screw  50 , formed by the neck  52 C and by the clamping head  52 , will therefore tend to expand isotropically with respect to the axial point  58 A, i.e. will occupy a homothetic position with respect to the position in the cold condition. As, according to the recommended feature, the ramps mentioned above are oriented according to the local homothetic direction, the clamping contact surface  55 A thus slides over the seat surface  15 A, without moving away from it, therefore preventing any unclamping, and without increasing the bearing pressure.