FR2505220A1 - DEVICE FOR FIXING INTERCHANGEABLE CUTTING INSERTS ONTO A TOOL HOLDER - Google Patents

Abstract

DEVICE FOR FIXING INTERCHANGEABLE CUTTING INSERTS, CHARACTERIZED IN THAT THE VALUE OF THE ANGLE OF CONE B IS BETWEEN 100 AND 160.

Description

The invention relates to a device for fixing the platelets of

  interchangeable cutting on a tool holder The fixing element used for this purpose consists of a head and a rod, and engages by its chamfered and hollow part, moreover, in the cutting insert. the clamping element can be screwed, for example, into a cylindrical recess in the tool-holder element The cutting insert and the tool-holder element are superimposed so that the central axes of the perforations are offset

  relative to each other The blocking of the cutting insert, which is now

  bare on a bearing surface and against at least one lateral bearing wall, is achieved by the fact that the head of the clamping element is placed, under the effect of the positioning of the rod in the holder -tools, against the chamfered area of the recess housing the cutting insert, which means that this insert

  cut is placed against the bearing surface and against the side edge of the holder

  tools. Cutting inserts of which the basic shape is a negative prism must be applied only and tightly against a side wall, which

  this is not the case for inserts with a general draft angle-

  orthogonal For this purpose, a cylindrical fixing hole made in the cutting insert is considered sufficient. With regard to the inserts which must be applied simultaneously against a side wall and

  against the load-bearing surface, this type of pad was fitted with a changeable zone

  braked, in addition to the perforation right through.

  Such a fixing system is the subject of the German utility model No. 72 37 608 The cutting insert is equipped with a hole which, in its upper part, widens to take a conical shape The fixing screw ensuring the clamping comprises a countersunk head corresponding to the conical flare. The tightening of this screw causes the application of the cutting insert against the tool holder seat The disadvantage of this system lies in the fact that, to replace the insert, the fixing screw must be unscrewed over its entire length At the relatively long time taken for replacement

  such a cutting insert adds the risk of losing the unscrewed screw,

laterally small.

  This drawback is eliminated by the fastening element for

  cutting quette described by the German patent N O 23 33 240 Indeed, the ele

  removable clamping screw is screwed into the tool body by means of

  diary of a thread whose axis forms, with the axis of the hole made in the cutting insert placed on the support surface, an angle less than 900 with respect to the vertical led to this support surface , so that the curvature of the clamping surface of the screw head corresponds to the curvature of the inner wall of the hole in the cutting insert placed, at least partially, against the lateral surface of the cone, and which rests against the inner face of the piercing of the cutting insert, and more precisely against a limited support zone in the peripheral direction of the piercing, after which the center of the curvature of the clamping surface of the clamping head of each fastening elements, placed on the lateral surface of the cone, lie along at least part of the peripheral surface, and

  in an eccentric position relative to the longitudinal axis of the fastening element.

  This fixing system, according to which the fixing element comprises a head whose diameter is less than the smallest diameter of the fixing hole of the cutting insert, makes it possible to replace this insert by only unscrewing the fixing element of the tool body With this device, everything

  as, moreover, with the device defined in the utility model cited above.

  ceded, the angle of the cone of the part of the head, which, in the tight position,

  applies against the cutting insert, is significantly less than 90 It ap-

  thus appears that this cutting insert is pressed essentially against the side wall, and slightly against the carrying surface The disadvantage of this method lies in the fact that the inevitable tolerances on the tool and on the cutting insert make the attackpoints between the head and the cutting insert are located in different areas, hence irregular and imprecise clamping conditions Furthermore, the fixing element is in

  oblique position relative to the bottom of the seat of the pad, which can pro-

  also evoke a shift in the point of attack Finally, the fastening element of this device is exposed, taking into account the relatively acute angle of the cone, to strong bending stresses The external surface of the head of the tightening screw defined by the German utility model no. 72 37 608 applies practically in its entirety against the surface of the recess

  practiced in the plate, whereas, on the device which is the subject of the German patent

  mand N O 23 33 240, the fastening element, subjected to significant forces of

  traction and bending, risk of breaking.

  It is therefore incumbent on the present invention to define a device for fixing the removable cutting inserts on a tool holder using a fixing element which guarantees a secure seat of the cutting insert on the tool holder, allows quick and easy replacement of this plate, and protects the fastening element against tensile and bending stresses

too important.

  The question thus posed is resolved using a device for fixing interchangeable cutting inserts on a tool-holder element, comprising a bearing surface and at least one lateral bearing wall, using

  a support element which, comprising a head and a rod, passes through a

  chamfered in a cutting insert and hangs in a

  cement, essentially cylindrical, used in the tool holder, ie

  say that it is screwed into a threaded zone partially covering the cylindrical hole, as a result of which the axis of symmetry of the hole practiced in the

  cutting insert and the axis of symmetry of the hole, of a relative diameter-

  smaller, made in the tool holder, are parallel and offset from each other, so that the head of the fastening element held in the tool holder rests against the chamfered area, and that the cutting insert bears both against the horizontal bearing surface and against the lateral bearing wall of this tool holder, which device is characterized in that the head of the fixing element has, according to a known method at the level

  current technology, a diameter smaller than the smallest diameter of the drill

  practiced in the cutting insert, but a diameter greater than the diameter

  meter of the rod of this same fixing element, and in that this fixing element comprises a frustoconical transition zone located between its head and its

  rod, as a result of which the axial section of the outer surface of the truncated area

  conical has a cone angle greater than 90 'The frustoconical transition zone between the head and the rod, i.e. the zone which ensures the transmission of the clamping forces on the plate

  cut, is advantageously designed so that the main components

  blades of the clamping forces act on the bearing surface of the insert,

  while the secondary components act in the direction of the lateral support.

  The bending stress of the fastening element is thus maintained before

  tagging at a very low level, since at the time of tightening, this

  fixing element can practically neither deviate nor be offset laterally-

  Finally, the holes in the cutting insert, as well as in

  the tool holder, can be made perpendicular to the surface of the appliance.

  then the seat of the cutting insert, which greatly facilitates machining work In addition, the advantage provided by the ease and speed of the

  replacement of the cutting insert has been fully maintained.

  According to one embodiment of the invention, the angle of the cone of the frustoconical transition zone between the head and the rod is between 1000 and 1600 The cutting insert has a drilling through and through, as well as a zone

  chamfered adapted to this frustoconical transition zone.

  Quick replacement of the cutting insert is favored before-

  by a fixing element, the pitch of which preferably represents

  rence 0.2 to 0.4 times the diameter of the threaded rod.

  According to another embodiment of the object of the invention, the head

  and / or the opposite end of the fixing element carries a cavity for the

  for example, the production of a hexagon key

  quick replacement of the cutting insert.

  To hold the fastening element in the tool holder, it has been

  demonstrated that it was sufficient to thread only the lower part of the cylinder rod

drique.

  Finally, it is possible to use, between the tool holder and the plate

  cutting quet, a removable support plate, which is held in place with a threaded socket screwed into the tool holder This threaded socket has a

  traditional drilling hole receiving the fixing element.

  According to yet another embodiment of the subject of the invention, it is possible to advantageously replace the screwed fixing by a coil spring or by a disc spring, making it possible to block and unblock

  easily the fixing element To do this, the end of the cylinder rod

  pin of this fastening element is provided with an annular flange, against which the coil or disc spring, sliding in the axial direction, bears

  on this cylindrical rod The opposite bearing surface is on the holder

  tools, which means that the coil or disc spring, compressed, supports the fixing element, and a fortiori the cutting insert, effectively against

the tool holder.

  Other features and advantages of this invention will emerge

  of the description given below, with reference to the appended drawings, which in it-

  polish various embodiments devoid of any limiting character.

  In these drawings: FIG. 1 represents a cross section of a removable cutting insert held on the tool holder by means of a fixing element; FIG. 2 represents a device according to FIG. 1, which, in addition, has an intermediate piece in the form of a support plate held in place with a threaded sleeve; and,

  Figures 3 and 4 show a cross section of a plate

  removable cutting quilt, held on the tool holder by means of a pushed fastening element, by a coil spring or a disc spring, against the

tool holder seat.

  The device represented in FIG. 1 essentially consists of a tool-carrying element 1, a cutting insert 2, and a fixing element 3 The removable cutting insert 2, generally made of hard metal, is traditionally held in an appropriate recess, made in the tool holder 1 The through hole 4 of the cutting insert 2 has, on its upper end, a chamfered area 5 The fixing element 3 consists of a head 3 a , of a frustoconical transition zone

  3 b, and a rod 3 c which, on its lower part 6 b, has a threaded area.

  The upper part 6 a of the rod 3 c consists of a connecting piece

  cylindrical ment which provides lateral guidance of the fastening element 3 internally

  inside of the tool holder 1 The diameter of the through hole 4, in the cutting insert 2, is greater than the diameter of the head 3 a of the element

  fixing 3 The axes of symmetry 7 of the fixing element 3, and 8 of the piercer

  ment 4, that is to say their respective median axes, are mutually parallel, so that when the fastening element 3 is tightened, the area of

  frustoconical transition 3 b rests against the chamfered frustoconical zone 10.

  The eccentric position of the clamping element thus guarantees safe positioning of the cutting insert 2 The clamping force caused by the fastening element 3 acts, taking into account the obtuse angle / 1 of the truncated cone, which is of

  '' in the example cited, mainly in the direction of tool holder 1 Ain-

  if, the embodiment shown schematically in Figure 1 solves, among other things, the problem underlying the invention, by the fact that the cutting insert 2 bears closely against both the side support wall 11 of the tool holder 1

  as against the horizontal bearing surface 12 of this same tool holder 1.

  To replace the cutting insert 2, the fixing element is unscrewed.

  tion until the plate 2, or even the piercing 4 made in this

  plate, can be slid over the head 3 a of the fixing element 3.

  For the installation of the replacement plate, we proceed in

  reverse order, taking care to screw the fixing element into the holder

  tools 1 until, under the effect of the force directed towards the sur-

  face 10, the cutting insert 2 is applied tightly against the lateral support wall II and against the horizontal support surface 12 of the tool holder 1 Le

  embodiment model defined by the invention applies essentially to the devices

  positive on which the lateral support wall 11 and the horizontal support wall

  form an angle of 90 or more between them.

  The embodiment shown schematically in Figure 2 differs from the model commented above by a support plate 13 placed, as an intermediate piece, between the cutting insert 2 and the tool holder 1 This support plate 13 is maintained in place by a threaded sleeve 14, screwed into a

  tapped hole in the tool holder 1 Finally, the element

  fastening ment 3 is screwed into the hollow inner part of the sleeve.

  The vertical immobilization, as well as the lateral immobilization of the support plate 13, are obtained by the fact that the appropriate bore 15 carries, on its

  upper end, a flared area 16 Thus, the upper end widened

  as a consequence of the socket 14 acts, by means of its truncated zone

  conical 17, on the support plate 13, which is thus applied tightly against the vertical and horizontal walls of the tool holder 1 The inclination of the frustoconical area 17 is such that the angle thus formed is also an obtuse angle.

  As can be seen in Figures 3 and 4, it is also pos-

  able to replace the screw thread with a coil spring or with a disc spring 18, to block the fastening element 3 For this purpose, this spring 18 is housed in a recess 19 formed in the tool holder 1, and pushes this fixing element 3 against the tool holder 1, that is to say against the horizontal and vertical support walls 11, by acting on a flange 20 which equips the free end of the fixing element 3 L ' advantage of this model

  of execution, compared to the models shown in Figures 1 and 2,

  side in the fact that we can delay the rotational movement between the element

  fixing and the removable cutting insert.

  On the execution model of FIG. 4, the fixing element is offset by approximately 900, so that the restoring force of the coil or disc spring 18 acts, either parallel to the bearing surface, at the seat

  of the cutting insert, or at a very reduced angle to this over-

  face This moreover takes all its importance in the case where one equips milling tools with the device defined by the invention. To deposit the cutting inserts, it suffices to neutralize the coil or disc springs.

  using a lever mechanism, for example.

  The fixing device defined by the invention applies of course, without any difficulty, to tools with several cutting edges, such as cutters,

  drills, tools to counterbore or to room.

8 2505220

Claims (5)

  1 Device for fixing interchangeable cutting inserts on a tool-carrying element, comprising a bearing surface and at least one lateral bearing wall, using a bearing element which, comprising a head and a rod, passes through a chamfered hole made in a cutting insert, and is blocked in a hole, essentially cylindrical, made in the tool holder, that is to say that it is screwed into a threaded area partially covering the cylindrical drilling, after which the axis of symmetry   of the hole made in the cutting insert and the axis of symmetry of the hole   relatively small in diameter in the tool holder are   parallel and offset from each other, so that the head of the element   fixing element, held in the tool holder, leans against the changing area   braked, and the cutting insert rests so much against the bearing surface   horizontal than against the side support wall of this tool holder, which   positive is characterized in that the head (3 a) of the fastening element (3) pre-   feels, according to a method known in current art, a diameter less than the smallest diameter of the hole (4) made in the cutting insert, but a diameter greater than the diameter of the rod (3 c) of this same element fixing (3), and in that this fixing element (3) comprises a frustoconical transition zone (3 b) located between its head (3 a) and its rod (3 c), after which the axial cut of the outer surface of the frustoconical area   has a cone angle greater than 90 (4).   2 Device for fixing interchangeable cutting inserts according to claim 1, characterized in that the value of the cone angle / ô is between 100 and 160 '.   3 Device for fixing interchangeable cutting inserts   according to one of claims 1 and 2, characterized in that the rod (3 c) of   the fixing element (3) comprises a screw thread, the large pitch of which advantageously reaches 0.2 to 0.4 times the value of the diameter of the opinion.   4 Device for fixing interchangeable cutting inserts according to claim 1, characterized in that the head (3a) and / or the end   opposite of the fixing element (3) comprises, for the purposes of fixing   tion, a hexagonal opening, for example, for the introduction of a key appropriate male clamp.   Device for fixing interchangeable cutting inserts   according to claim 1, characterized in that the rod (3 c) of the fixing element   tion (3) has a cylindrical shape and has a thread only on its lower part (6 b). 6 Device for fixing interchangeable cutting inserts   according to claim 1, characterized in that the tool-carrying element (1) comprises   door, between the cutting insert (2) and the tool holder (1), an intermediate piece   diary in the form of a removable support plate (13) which, according to a method   known per se, is held by a socket (14) which is screwed into the drill   practiced in the tool holder (1) and which houses, in its hollow interior part   the fixing element (3).   7 Device for fixing interchangeable cutting inserts   according to claim 1, characterized in that the rod (3 c) of the fixing element   tion has an annular flange (20) which serves as a bearing surface for the spring   with tubes or discs (18) which is placed on the rod (3 c), and which pushes the element   fixing ment, in the direction of the axis of symmetry, against the bearing surface (12) of the tool holder.