TOOL FOR CHIP REMOVING MACHINING

Abstract: The invention relates to a tool for chip removing machining and a blade therefor. The tool comprises a holder (11), an elongated blade (12) and an insert (13). The holder is provided with an expandable securing part (14) and a head (15) having a longitudinally recess (19) arranged to receive the blade (12). The blade has an insert site which receives the insert (13). The blade is provided to be wedged up in the holder in the longitudinal direction of the blade and in two directions perpendicular thereto.

Description: The present invention relates to a tool for chip removing machining and a blade arranged therein. The tool comprises a holder, a planar, elongated blade and a cutting insert. The holder have an expandable securing part and a head attached thereto comprising a longitudinaly extending first recess having bordering edge surfaces at least partly forming a dove-tail profile. The blade has a cutting insert site at a front surface thereof, an end surface, side surfaces and edge surfaces. The edge surfaces at least partly form a dove-tail profile. The blade is wedgingly urged towards a lower one of said bordering edge surfaces by means of tightening means. In US-A-3.775.818 is shown a parting tool comprising a holder, a blade and an insert. The holder is provided with a clamping device which is adapted to clamp the blade in a direction transverse to the longitudinal direction of the blade and to simultaneously clamp the insert. That type of tool lacks a well defined stop in the longitudinal direction of the blade and demands close tolerances on the holder and the blade such to avoid tilting in the holder and therefore the tool is adapted for small cutting forces only. One object of the present invention is to shape a tool and a blade such to obtain a stable and secure tool system. Another object is to obtain a flexible tool system i e a tool wherein the blade is easily and quickly exchangeable regardless of the dimension thereof. Another object is to obtain a tool system which is unsensitive to tolerance faults. These and other objects have been obtained by shaping the tool and the blade in accordance with the following claims. The invention will be more closely described hereinafter in connection with the appended drawings. Fig. 1 shows a tool according to the invention in a side view. Fig. 2 shows the tool in a top view. Fig. 3 shows a cross-section according to the line III-III in Fig. 1. Fig. 4 shows an end view of the tool. Fig. 5 shows an exploded view of the tool. In the figures is shown a parting tool 10 for chip removing machining. The tool comprises a holder or adapter 11, a blade 12 and an insert 13. The adapter has an, in itself previously known, expandable securing part 14 arranged to be clamped in a machine. The securing part is more closely described in US-A-4.270.422 which is hereby incorporated with the description. The part 14 connects to a head 15 which extends forwardly and sidewardly relative to the part 14. The head has a planar upper side 15′, a front surface 16, a side surface 17, an end surface 18, a lower side and a backed off surface. A first recess 19 is formed in the head, which extends along the entire side surface 17 and terminates in the front surface 16 and the end surface. The recess 19 is bordered by two edge surfaces 20, 21 and a bottom 22. The edge surfaces 20, 21 form a dove-tail profile, i e they converge in direction perpendicularly from the bottom 22. The enclosed angle is about 10 to 40 degrees. The lower edge surface 20 is mainly parallel with the center line CL of the tool 10. The upper edge surface 21 forms an acute angle α with the edge surface 20 in direction towards the securing part in the plane of the side surface 17, i e rearwardly. The angle α is chosen within the interval 10 to 20 degrees, preferably about 15 degrees. The edge surface 20 is preferably provided with a rear and a front lip for heel and toe abutment, respectively, for the blade. The bottom 22 is planarly shaped and has a groove 23 arranged along the entire length of the bottom. The groove 23 reduces the risk for tilting of the blade in the recess and may in certain cases be used for transference of cooling liquid. A second recess 24 is formed in the head 15. The recess 24 is mainly square and terminates in the side surface 17 and in the recess 19. The recess 24 extends a distance a in the depth direction from the plane of the side surface 17. The distance a is at least twice the thickness c of the blade 12. The recess 24 is placed such that it is closer to the end surface 18 than to the front surface 16. The upper part of the recess 24, closest to the upper side 15′, forms an internal acute angle with the upper side. The lower part of the recess, closest to the lower side of the head, is mainly parallel with the upper side 15′. Said parts of the recess are connected by two guiding surfaces which are mainly parallel with the plane of the front surface 16. The recess 24 has corners which are rounded off due to durability reasons. A bore 25 is formed in the head 15. The bore 25 is perpendicular to the plane of the side surface 17 and terminates in the middle of the recess 24 and in the backed off surface of the head. The bore is threaded from the recess 24 and a distance into the head whereafter it has been expanded to provide space for a key tool. The threaded part of the bore 25 is arranged to receive one end of a stretching screw 26, i e a screw whose ends 27, 28 are threaded mutually opposite. The second end 28 of the screw 26 will engage with a threaded bore in a wedge 29. The wedge 29 consists of two mainly planar and parallel side surfaces, two mainly planar and parallel guiding surfaces and two towards the head 15 converging wedge surfaces 30, 31. The wedge surfaces converge towards a point on the center line CL₂. A lower wedge surface 30 is provided with transversely extending ridges 32 provided to reduce the tolerance sensitivity of the wedge. The corner portions of the wedge are chamfered. The upper wedge surface 31 is provided to engage with and to slide along the upper sloping part of the second recess 24. The thickness of the wedge is less than the depth a of the recess 24 but larger than the thickness c of the blade 12. The blade 12 comprises two mainly plane-parallel side surfaces, a front surface, an end surface 33 and two edge surfaces 34, 35. A cutting insert site is formed in the front end of the blade to receive an insert 13. The insert and the insert site are more closely described in the Swedish patent application No. 8601533-6, which is hereby incorporated with the description. The lower edge surface 34 is roof-shaped, i e has the shape of an inverted V, and is arranged parallel with the center line CL₁ of the tool. The upper edge surface 35 is partly at 35a parallel with the centerline CL₁ while a first portion 35B forms an acute angle β with the lower edge surface 34 in such a way that the portion 35B converges rearwardly towards the edge surface 34 in direction towards the end surface 33. The angle β is chosen within the interval 10 to 20 degrees, preferably about 15 degrees. The angle β shall be about 0.5 degrees less than the angle α . The edge surface 35 is along a second section 35C arranged mainly parallel with the edge surface 34. Also the upper edge surface 35 is roof-shaped such that the outer edges of the edge surfaces 34,35 facing away from the recess 19 form an acute angle with each other. The second section 35C is in the height direction of the blade arranged at a distance b from the rear end of the first section 35B. The distance b is about 40 to 60 percent of the largest height of the blade. The section 35B transites into the section 35C via an edge perpendicular to the lower edge surface 34 and a rounded off corner. An extension line of the section 35B does not intersect the section 35C in any point but converges in direction rearwardly towards an extension line of the section 35C. When mounting of the tool the ends 27, 28 of the screw 26 are threaded into the bore 25 of the head and into the bore of the wedge 29, respectively, without tightening too much. The wedge 29 is thereby in an open position. The blade 12, provided with an insert, is thereafter inserted from left in Fig. 1 and into the recess 19 in the head. The second section 35C of the blade may therefore slidingly pass the lower part of the wedge. As the enclosed angle α between the edge surfaces 20, 21 is less than the angle β between the edge surface 34 and the second section 35B of the edge surface 35 the blade will be wedged up on the front part of the recess, i e at the intersections of the edge surfaces 20, 21 and the front surface 16. In this position the wedge is tightened by the screw from one of the possible two directions whereby the upper part 31 of the wedge will contact with the upper part of the second recess 24 while the ridges 32 on the lower part 30 of the wedge will contact the second section 35C of the blade and thus the blade will be forced downwardly towards the edge surface 20 and inwardly towards the bottom 22. Bending moment on the screw 26 is avoided by the surfaces 31 and 32 forming equal angles with the center line CL₂ of the bore 25, and therefore the screw will only be loaded with tensile stress. The edge surface 21 in the first recess and the first section 35B of the blade constitute axial stop means, i e prevent unwanted insertion of the blade into the first recess. The ridges 32 of the wedge 29 and the second section 35C prevent tilting of the blade in the recess. The blade is thus wedged up in the holder in the longitudinal direction of the blade and in at least one direction perpendicular thereto, i e perpendicular to the side surface 17, at two from each other spaced contact places. The contact places are defined by the front contact place between the surfaces 34, 35B and the surfaces 20, 21 and the other contact place is defined by the rear contact place between the surfaces 34, 35C and the ridges 32. The invention thus relates to a tool for chip removing machining through which shape a flexible and stable tool system is obtained.

Claims: 1. Tool for chip removing machining comprising a holder (11), a planar, elongated blade (12) and a cutting insert 13, said holder having an expandable securing part (14) and a head (15) attached thereto comprising a longitudinally extending first recess (19) having bordering edge surfaces (20,21) at least partly forming a dove-tail profile, said blade having a cutting insert site at a front surface thereof, an end surface (33), side surfaces and edge surfaces (34,35), said edge surfaces (34,35) at least partly forming a dove-tail profile, said blade being wedgingly urged towards a lower one of said bordering edge surfaces (20) by means of tightening means (29),characterized in that the blade (12) is arranged to be wedged up in the holder (11) in the longitudinal direction of the blade and in two directions perpendicular thereto, said blade and holder comprising wedgingly co-operating first contact surfaces (21,35B) which are provided to determine the position of the blade in the longitudinal direction of the blade, wedgingly co-operating second contact surfaces (32,35C) which are provided to determine the position of the blade in the transverse direction of the blade parallel with the plane of the blade and wedgingly co-operating third contact surfaces (21,35B,32,35C) provided to determine the position of the blade in the transverse direction of the blade normal to the plane of the blade. 2. Tool according to claim 1,characterized in that the edge surfaces (20,21) of the first recess (19) at least partly enclose a first acute angle (α) and in that one edge surface (34) of the blade (12) and a first section (35B) of the second edge surface (35) of the blade enclose a second acute angle (β) and in that the tightening means (29) engage a second section (35C) of the second edge surface (35) of the blade which section connects to the end surface (33) of the blade. 3. Tool according to claim 2,characterized in that the first angle (α) and the second angle (β) are in the magnitude of 10 to 20 degrees and in that the second angle (β) is about 0.5 degrees larger than the first angle (α). 4. Tool according to claim 2,characterized in that the second section (35C) of the second edge surface (35) of the blade extends mainly parallel with the first edge surface (34) of the blade which first edge surface is mainly parallel with a center line (CL₁) of the tool. 5. Tool according to anyone of the preceding claims,characterized in that the head (15) comprises a planar upper surface (15′),a planar front surface (16), a side surface (17), an end surface (18), a lower surface and a backed off surface and in that the first recess (19) extends along the side surface (17) and terminates in the front surface and the end surface, said recess (19) having a mainly planar bottom (22) along which a groove (23) extends. 6. Tool according to claim 5,characterized in that a second recess (24) is formed in the head (15) which terminates in the bottom (22) of the first recess (19) and in the side surface (17), an upper part of said second recess facing away from the upper surface (15′) of the head, sloping and forming an acute angle with the upper surface and in that a threaded bore (25) arranged perpendicularly to the side surface (17) terminates in the middle of the second recess (24) and receives a screw (26) which is in threaded engagement with a wedge (29), said wedge having surfaces (31,32) which form equal angles with the center line (CL₂) of the bore (25) and said surfaces co-operating with the upper sloping part of the second recess and a second section (35C) of a second edge surface (35) of a blade, respectively, in order to force one edge surface (34) of the blade against one lower border surface (20) of the first recess. 7. Tool according to claim 6,characterized in that one surface (30) of the wedge (29) and one border surface (20) of the first recess (19) are provided with projections arranged at respective end of respective surface (30,20). 8. Tool according to anyone of the preceding claims,characterized in that the second recess (24) has a depth (a) which is at least twice the thickness (c) of the blade (12) and in that the thickness of the wedge is less than said depth a but larger than said thickness (c). 9. Blade provided to carry an insert and to be clamped in a holder comprising an insert site, plane-parallel side surfaces, a front surface, an end surface (33) and edge surfaces (34,35), said edge surfaces having at least partly dove-tail profiles,characterized in that a first section (35B) of one edge surface (35) forms a second acute angle (β) with the other edge surface (34) and in that a second section (35C) of said one edge surface (35) arranged between said first section (35B) and the end surface (33) is mainly parallel with the second edge surface (34). 10. Blade according to claim 9,characterized in that the second acute angle (β) is between 10 to 20 degrees and in that an extension line of the first section (35B) converges towards an extension line of the second section (35C).

Inventors: BYSTROEM, OLOF LENNART, JOHANSSON, SVEN-ERIK WILHELM, Byström, Olof Lennart
Applicants: SANDVIK AKTIEBOLAG
Application year: 1987
Main classification: B23B29
IPC codes: B23B27, B23B29