Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
  • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
  • B23B27/16—Cutting tools of which the bits or tips or cutting inserts are of special material with exchangeable cutting bits or cutting inserts, e.g. able to be clamped
  • B23B27/1659—Cutting tools of which the bits or tips or cutting inserts are of special material with exchangeable cutting bits or cutting inserts, e.g. able to be clamped with plate-like exchangeable cutting inserts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2205/00—Fixation of cutting inserts in holders
  • B23B2205/12—Seats for cutting inserts

Definitions

• the present invention relates to the sector of cutting tools and more in particular of mechanisms for fixing cutting inserts on insert holders.
• a cutting tool is formed by one or more blades, or cutting edges, adapted to remove material from a workpiece by bringing the cutting edge into contact with the workpiece and moving said cutting edge with respect to the workpiece, or vice versa.
• the cutting edges of cutting tools become worn rapidly when they are used for removal operations, especially on hard materials such as metal, and must therefore be replaced relatively frequently.
• Many cutting tools such as those for turning, milling or boring, are provided with one or more cutting inserts, on which one or more cutting edges are obtained, fixed in a seat obtained in a support known as insert holder.
• the insert is held in the seat of the insert holder by means of blocking mechanisms that allow the insert to be removed and repositioned (for example to use a new cutting edge on the same insert) or to replace the worn insert with a new one.
• One type of widely used known blocking mechanism comprises a blocking pin, screwable in a threaded hole obtained at the seat of the insert holder, with an end projecting in the seat and structured to engage a hole obtained in the insert. Examples of these known tools are described in EP 0037554 Al, US 3341919 A, US 3805351 A and US 3913197 A.
• this blocking system is compatible with inserts in which the hole has a shape and a size suitable to couple with the blocking pin.
• a blocking mechanism of another type comprises a bracket, fixable to the insert holder by means of a screw, adapted to press the insert onto the bottom of the seat, and optionally against at least one lateral wall, to block it in position. Examples of these known tools are described in US 3027623 A and US 3138846 A. This blocking mechanism, more practical to handle, can however only be used on tools for external machining operations, as the bracket would obstruct the discharge of swarf removed during internal machining operations.
• Yet another type of blocking mechanism comprises a pin, housed in the hole of the insert, integral with a lever that extends from the lower end of the pin. Located on the opposite end of the lever is a screw that, causing rotation of the lever and of the pin, carries the insert into contact with abutment walls of the seat of the insert holder. Examples of this blocking mechanism are described in US 3908255 A and US 851 1944 B2.
• the lever is somewhat limited in size in order to be housed under the insert and, for this reason, is often subject to breakages, making this type of tool somewhat unreliable and costly to maintain.
• an object of the present invention is to propose an insert holder for a cutting tool provided with a blocking mechanism of the insert that overcomes the aforesaid drawbacks of the prior art.
• Another object of the present invention is to propose an insert holder provided with a blocking mechanism that can be used with a wide range of inserts and for different types of machining operation.
• a further object of the present invention is to provide an insert holder that allows all the available cutting edges of an insert to be used. In addition to the aforesaid objects, it is also an object of the present invention to produce an inexpensive and sturdy insert holder.
• an insert holder for receiving and releasably blocking an insert provided with a central hole, comprising:
• a body with a seat for receiving the insert said seat having a base surface and a pin, integral with the body, projecting from said base surface to engage the central hole of the insert;
• a blocking means positioned between a second lateral face of the insert and a second erect supporting surface of the seat of the insert.
• Said blocking means has a first lateral wall, movable toward said second lateral face of the insert, and a second lateral wall, movable toward said second erect supporting surface.
• first lateral wall of the blocking means is substantially parallel and adjacent to the second lateral face of the insert, and the second lateral wall is substantially parallel and adjacent to the second erect supporting surface.
• said blocking means is mounted on said body by means of a screw, passing through a hole obtained on said blocking means, screwable in the body of the tool holder.
• the blocking means in response to clamping of said screw, can be moved from a free position, in which the insert can be positioned in the seat or removed therefrom, to a blocked position, in which the first lateral wall of the blocking means engages the second lateral face of the insert, exerting a thrust thereon.
• the blocking movement of the insert can be carried out practically and rapidly.
• the pin integral with the body of the insert holder also allows the insert to be positioned precisely in the seat to block it.
• Removal of the insert from the seat is also just as rapid and simple. In fact, it is sufficient to loosen the screw, without extracting it, to eliminate the thrust exerted by the first face of the blocking means on the insert.
• the insert holder of the present invention can be used with bilateral inserts (with zero or negative rake angle). In this way, the largest number of cutting edges of the insert can be used, rotating it with respect to the pin or turning it over with respect to the supporting surface.
• the blocking means can advantageously be structured so as to have the same thickness as the insert or, in any case, not to project beyond the outline of the insert holder.
• the tool thus produce can be used in any type of machining operation, whether external or internal.
• said blocking means is preferably in the form of a flat plate of substantially constant thickness. This makes it particularly sturdy limiting the possibility of breakages and thereby reducing the expenditure for spare parts.
• the seat can comprise at least a first erect supporting surface, adjacent to an inner side of the base surface and movable toward a first lateral face of the insert. In the blocked position, the first lateral face of the insert is pressed against said first erect supporting surface.
• the larger surface subject to the friction force caused by the thrust of the blocking means makes blocking of the insert in the seat even safer.
• the first lateral wall and the second lateral wall of the blocking element can be convergent toward the hole in which the fixing screw is housed.
• the blocking element can therefore act as a sort of wedge that, following clamping of the screw, is simultaneously thrust against the second lateral face of the insert and the second erect supporting surface.
• the angle a between the lateral walls of the blocking means is between 22° and 34° and more preferably between 26° and 30°. These values of the angle a ensure a sufficient thrust to block the insert and simultaneously limit the movement that the blocking means must carry out between the free position and the blocked position.
• the screw can comprise a threaded portion, screwable in a threaded hole obtained on the body, and a widened head received in the hole obtained on the blocking means.
• the head has a smaller cross section than that of the hole and includes a truncated-cone shaped surface adapted to engage a respective shaped surface of the hole, to move the blocking means when the screw is clamped.
• the blocking means is structured so that, when the first lateral wall is in contact with the second lateral face of the insert, and the second lateral wall is in contact with the second erect supporting surface of the seat, the axes of the threaded hole on the body and of the hole on the blocking means are moved away by a distance substantially aligned along the direction of movement of the blocking means.
• the first erect supporting surface of the seat or the first lateral wall of the blocking means, or both can be substantially perpendicular to the base surface of the aforesaid seat.
• FIG. 1 is an exploded perspective view of a cutting tool according to the invention
• FIG. 2 is a perspective view of the tool of Fig. 1, with the insert positioned in the related seat;
• Figs. 3a and 3b are respectively a top view and a cross sectional view along a plane A- A of the tool with the blocking means in free position;
• Figs. 4a and 4b are respectively a top view and a cross sectional view of the tool with the blocking means in blocked position;
• Fig. 5 is a cross sectional view along a plane B-B of the tool of Fig. 4a;
• FIG. 6 is a side view of the tool of Fig. 2;
• Figs. 7 to 15 are the top views of variants of the tool according to the invention, suitable for mounting inserts of different shapes;
• FIG. 16 is a perspective view of an internal cutting tool, according to the invention.
• the numeral 1 indicates as a whole a cutting tool, typically suitable for stock removal machining operations on metals or other materials.
• the tool 1 comprises an insert holder 10 with a body 11, obtained on which is at least one seat 20 to house a cutting insert 30.
• the insert holder 10 also comprises a blocking means 40 configured to secure said insert 30 in the aforesaid seat 20.
• the insert holder 10 is suitable to accommodate inserts 30 provided with a central hole 31 passing between an upper side 32 and a lower side 33.
• the central hole 31, preferably, is cylindrical for the majority of its extension.
• the insert 30 has a quadrilateral plane shape and, more in detail, a rhomboid plane shape. Therefore, the insert 30 has four lateral faces 34-37 that extend between the upper side 32 and the lower side 33. The insert 30 has at least one cutting edge 38, defined by the meeting between a lateral face 34 and the upper side 32, which projects beyond the body 11 of the insert holder 10 to contact a workpiece during machining.
• the seat 20 comprises a base surface 21, adapted to receive the insert 30 resting thereon, and at least a first erect supporting surface 22, which extends from an inner side of the base surface 21.
• said supporting surface 22 comprises at least a flat segment substantially perpendicular to the aforesaid base surface 21.
• the base surface 21 is obtained directly on the body 11 of the insert holder 10.
• said base surface can be obtained on an intermediate plate (or sub-insert) interposed between the body 11 of the insert holder 10 and the insert 30.
• a pin 23 projects from the base surface 21, adapted to be housed in the central hole 31 of the insert 30, when the insert is arranged in the seat 20 and resting on the base surface 21 (Fig. 5).
• the pin 23 is preferably made in once piece with the body 1 1 of the insert holder 10 or, alternatively, can comprise a separate element, engaged in a hole obtained on the base surface 21. In both cases, the pin 23 is integral with the body 11 of the insert holder 10.
• the pin 23 is cylindrical in shape and has a diameter slightly smaller than the diameter of the hole 31 of the insert 30. This allows the insert 30 to be arranged precisely, but without forcing insertion of the pin 23 in the hole 31.
• the difference between the diameter of the pin 23 and of the hole 31 of the insert is between 0.05 mm and 0.20 mm.
• the first lateral face 35 of the insert is substantially parallel and adjacent to the first erect supporting surface 22 of the seat 20.
• the clearance between the diameter of the pin 23 and of the hole 31 allows the insert to perform a limited movement from a position in which the first lateral face 35 of the insert and the first supporting surface 22 are spaced by a few hundredths of millimetre, to a position in which said face and said surface are in contact with each other.
• the blocking means 40 comprises a body with a bottom wall 41, an upper wall 42 and at least a first lateral wall 43 and a second lateral wall 44.
• the two lateral walls 43, 44 are preferably flat and perpendicular to the bottom wall 41.
• a through hole 45 which extends between the upper wall 42 and the bottom wall 41, allows the passage of a screw 50 with which the blocking means is connected to the body 1 1 of the insert holder.
• the two lateral walls 43, 44 are convergent toward said hole 45.
• the angle a between said lateral walls 43, 44 is preferably between 22° and 34° and more preferably between 26° and 30°.
• the blocking means 40 is in the area of the seat 20, between the insert 30 and the second erect supporting surface 25 of the seat 20. More in detail, said blocking means 40 is arranged so that the first lateral wall 43 thereof is adjacent and substantially parallel to the second lateral face 36 of the insert 30 and the second lateral wall 44 thereof is adjacent and substantially parallel to the second erect supporting surface 25.
• the bottom wall 41 of the blocking means 40 rests sliding on a surface parallel to the base surface 21 of the seat 20.
• Said surface is preferably the same base surface 21 or another surface coplanar to this latter.
• the screw 50 which connects the blocking means to the body 11, comprises a threaded portion 51, screwable in a threaded hole 12 obtained on said body 11, and a widened head 52 that can be received at least partially in the hole 45 of the blocking means
• the head 52 comprises a truncated-cone shaped surface 53 adapted to engage a corresponding shaped surface 46, preferably also truncated-cone shaped, obtained on the internal surface of the hole 45 (Figs. 3b, 4b).
• the head 53 has a smaller cross section with respect to that of the hole 45 at the shaped surface 46, so as to be able to move laterally by a few hundredths or tenths of millimetre
• the blocking means 40 has a shape and a dimension such that when the first lateral wall 43 is in contact with the second lateral face 36 of the insert 30, and the second lateral wall 44 is in contact with second erect supporting surface 25, the axes of the threaded hole 12 and of the hole 45 are moved away by a distance G, aligned along a direction D (Fig. 3a).
• the blocking means is in a free position in which an insert 30 can be positioned in the seat 20 or removed therefrom.
• the truncated-cone shaped surface 53 of the head 52 is detached from the shaped surface 46 of the hole 45 or, as in the example in the figure, said surfaces are barely contacting each other, without interference, i.e. without mutual stress.
• the insert 30 is free to slide on the pin 23 to be positioned in, or removed from, the seat 20.
• the truncated-cone shaped surface 53 of the head 52 first contacts the shaped surface 46 of the hole 45 and subsequently, clamping the screw 50 further, starts to exert a thrust Fv directed along the direction D on said shaped surface 46.
• the blocking means 40 is moved along said direction D until simultaneously contacting the second lateral face 36 of the insert 30 and the second erect supporting surface 25. This latter acting as abutment causes the first lateral wall 43 to exert a respective thrust Fb on the second lateral face 36 of the insert 30.
• the insert 30 is moved until the first lateral face 35 is pressed against the first erect supporting surface 22 of the seat 20 and the internal surface of the hole 31 is pressed against the surface of the pin 23, as visible in Figs. 4a, 4b.
• blocking of the insert in the seat 20 can also take place without the first erect supporting surface 22 being present.
• the friction between the surface of the hole 31 and that of the pin 23 alone can be sufficient to maintain the insert in the seat.
• An example of this variant is illustrated in Fig. 13.
• the blocking means can move back toward the free position causing the thrust Fb to decrease gradually until the insert 30 is able to slide freely along the pin 23.
• FIGs. 7 to 15 illustrate other embodiments of the insert holder of the present invention, suitable to accommodate inserts 30 of different shapes, among those most commonly used.
• insert holder according to the present invention can be used with any bilateral insert or insert with a zero-rake angle, with central hole.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=56990785

Family Applications (1)

Country Status (3)

Families Citing this family (3)

Family Cites Families (10)

• 2016
  • 2016-05-24 IT ITUA2016A003754A patent/ITUA20163754A1/it unknown
• 2017
  • 2017-05-23 WO PCT/IB2017/053044 patent/WO2017203435A1/en unknown
  • 2017-05-23 EP EP17737364.4A patent/EP3463725A1/de not_active Withdrawn

Also Published As

Similar Documents

Legal Events