Cutting insert, cutting tool comprising such an insert and methods for producing and repairing such a tool

Abstract

The invention relates to an insert brazed on a body of cutting tools (101), consisting of: a metal substrate (11), in the form of plates, having a surface for attachment to the tool body; a high-temperature, brazing, alloy layer (12); an intermediate layer; and a ceramic plate (14). The brazing alloy layer connects the metal substrate (11) of the ceramic plate (14) via the metal layer (13). A low-temperature brazing layer (1) connects the insert (1, 1) to the body of the tool (101).

Claims

1. Cutting insert for brazing onto a cutting tool body for working wood-based composite materials, the cutting insert comprising: a substrate (11) in the form of a plate with a fastening surface (11 a) to the cutting tool body, where the substrate (11) includes tungsten carbide, steel, nickel steel, or a tungsten carbide-cobalt composite, a high-temperature brazing alloy layer (12) an intermediate metal layer (13) a ceramic plate (14) that consists of alumina (Al.sub.2O.sub.3), zirconia, zirconia-yttria, or a combination thereof, the ceramic plate (14) having the same dimensions as the substrate (11), the high-temperature brazing alloy layer (12) connecting the substrate (11) to the ceramic plate (14) by means of the intermediate metal layer (13), where the intermediate metal layer (13) is between the ceramic plate (14) and the high-temperature brazing alloy layer (12), and the high-temperature brazing alloy (12) is an alloy of silver-copper with more than 50% by volume of silver or an alloy of silver, indium, and titanium.

2. The cutting insert according to claim 1, characterized in that the substrate (11) is connected to the high-temperature brazing alloy layer (12) by means of a metal layer (15) comprising titanium.

3. The cutting insert according to claim 1, characterized in that the substrate (11) includes steel, nickel steel C45, or a tungsten carbide-cobalt composite.

4. Cutting tool comprising a rotary metal tool body (101), said body having an active surface that is aligned with two or more of the cutting inserts (1, 1) according to claim 1, the cutting tool characterized in that the cutting inserts (1, 1) are connected to the tool body (101) by a low-temperature brazing alloy layer (16), where the low-temperature brazing alloy layer (16) is between the active surface of the tool body (101) and the substrates (11) of the cutting inserts (1, 1).

5. The cutting tool according to claim 4, characterized in that the low-temperature brazing alloy is a silver-copper alloy containing at least 60% by volume of silver.

6. Production method of a cutting tool for working wood-based composite materials, the method comprising: a) using a ceramic plate (14) consisting of alumina (Al.sub.2O.sub.3), zirconia, zirconia-yttria, or a combination thereof, and a substrate (11) that includes tungsten carbide, steel, nickel steel, or a tungsten carbide-cobalt composite, the ceramic plate (14) having the same dimensions as the substrate (11), b) applying an intermediate metal layer (13) to the ceramic plate (14), c) applying a high-temperature brazing alloy (12) between the intermediate metal layer (13) and the substrate (11), d) brazing the ceramic plate (14) to the substrate plate (11) by high-temperature vacuum brazing with the high-temperature brazing alloy (12), the high-temperature brazing alloy (12) being an alloy of silver-copper with more than 50% by volume of silver or an alloy of silver, indium, and titanium, to form an assembly (20), e) cutting out of the assembly (20) obtained in this way a cutting insert (1 or 1), f) brazing the cutting insert (1 or 1) on to a tool body by brazing at atmospheric pressure, at low temperature, with a low temperature brazing alloy, to form the cutting tool.

7. The production method according to claim 6, characterized in that the step b) of applying the intermediate metal layer (13) to the ceramic plate (14) includes applying a coat of metallic paint.

8. The production method according to claim 6, characterized in that the vacuum brazing of step d) is carried out at a high temperature included between 760 C. and 820 C. and the brazing at atmospheric pressure in step f), is carried out at the low temperature included between 560 C. and 620 C.

9. The production method according to claim 6, further comprises a step of applying a brazing flux to the cutting insert (1 or 1) and the tool body before step f) of brazing at atmospheric pressure.

10. The production method according to claim 6, further comprising the step of sharpening the cutting inserts (1 or 1) using an abrasive grinder.

11. Process for repairing the cutting tool of claim 4, by replacing a cutting insert that has deteriorated, the process comprising: heating locally, at atmospheric pressure, the cutting tool to destroy the low-temperature brazing alloy layer between the substrate of the cutting insert that has deteriorated and the tool body; and attaching a new cutting insert having a substrate to the tool body by local brazing at atmospheric pressure and low temperature to form a new low-temperature brazing alloy layer between the substrate and the tool body.

12. The process of claim 11, wherein the step of heating the cutting tool to destroy the low-temperature brazing alloy layer comprises electromagnetic induction.

Description

ILLUSTRATIONS

(1) This invention will be described in greater detail in the following by means of examples of cutting inserts according to the invention, tools equipped with these inserts and a method of producing cutting inserts, cutting tools and of replacing a worn cutting insert on a tool, shown in the attached illustrations in which:

(2) FIG. 1 is a schematic sectional view at an enlarged scale of a first embodiment of a cutting insert according to the invention,

(3) FIG. 2 is a similar sectional view to FIG. 1 of an alternative embodiment of a cutting insert,

(4) FIG. 3 is a sectional view of a cutting insert according to the invention,

(5) FIG. 4 is a schematic view of an example of a cutting tool according to the invention;

(6) FIG. 5 is a plan view of a saw blade according to the invention,

(7) FIG. 6 is an axial sectional view of a finishing cutter according to the invention,

(8) FIG. 7 is a plan view of a tearing device according to the invention including two types of size cutting plates and of different sizes; and

(9) FIG. 8 is a plan view of a routing cutter according to the invention.

(10) FIGS. 9-11 are schematic illustrations of the successive steps of the production method of cutting inserts according to the invention;

DESCRIPTION OF PRODUCTION METHODS

(11) According to FIG. 1, the purpose of the invention is a cutting insert 1 represented schematically and at a much enlarged scale, in a sectional view. Direction D is the thickness of plate 1. Plate 1 the consists of a metal substrate 11 having a fastening surface 11 for attaching a plate 1 to the cutting tool body and a brazing surface 11b. The brazing surface 11 b is covered by a high-temperature braised alloy layer 12 itself covered or connected to a ceramic plate 14 by means of a metal layer 13. All these components 11, 12, 13, 14, assembled by brazing, have a substantially rectangular shape with the ceramic plate 14 covering the surface of the metal substrate 11. One or several faces of cutting insert 1 are sharpened, where applicable (the sharpened surface bears as an example the reference 1a).

(12) FIG. 2 is a sectional view similar to that of FIG. 1 of an alternative cutting insert 1 differing from cutting insert 1 of the FIG. 1 only in the presence of a second metal layer 15 between fastening surface 11 a of metal substrate 11 and the high-temperature braised alloy layer 12. The other components are identical or similar to those of FIG. 1 and bear the same references. Their description will not be repeated.

(13) The metal substrate 11 is a steel plate, of nickel steel C45, of tungsten carbide WCCo.

(14) The high-temperature braised alloy layer 12 is a silver-copper AgCu alloy having a silver content in excess of 50% by volume or otherwise and alloy 49Ag 27.5Cu 20.5Zn 2.5Mn 0.5Ni. It can be an AgCu alloy with the addition of Zn, Mn and Ni. The ceramic plate 14 is of alumina -Al.sub.2O.sub.3 or of zirconia-yttria 3YZrO.sub.2.

(15) FIG. 3 shows very schematically and in a much enlarged sectional view, a cutting tool 100 in location 102 of cutting insert 1. This tool 100 includes or many cutting plates depending on the work to be done with the tool 100. The cutting inserts 1, 1 are of identical or different sizes. The cutting inserts 1, 1 are connected to the body 101 of the cutting tool 100 at locations 102 by brazing with a low temperature brazed alloy layer 16. This low-temperature brazing alloy 16 is a silver-copper alloy AgCu containing at least 60% by volume of silver Ag.

(16) The plates 1, 1 are obtained by casting plates of larger sizes having the same layer structure as the plates 1, 1 described above and whose production method will be described in FIGS. 9 to 11.

(17) FIG. 4 shows a tool 110 in the form of a cutter on an axis xx of which the cylindrical body 111 is provided with cutting plates 112 according to the invention. These cutting plates 112 are rectangular or square, similar to the plates 1, 1 of FIGS. 1-3. Only two plates are shown whereas in reality the body 111 of the tool comprises several plates 112 set out regularly on the perimeter but also in the direction of axis of rotation xx, for instance, by the alternating arrangement from one crown of plates to the next, to regulate and densify the peripheral distribution of the plates and give the cutter 110 a height H1 corresponding to the axial length on which the plates 112 are distributed.

(18) The plates 112 are connected to the body 111 by brazing as indicated in FIG. 3, carried out using a low temperature brazing alloy allowing the local de-brazing of a damaged cutting insert 112 and its replacement by a new plate 112 which will be attached by local brazing.

(19) FIG. 5 is a plan view of a circular saw disc 120 consisting of a body 121 with an attaching hole 122 and peripheral teeth 123 each provided with a cutting insert 124. These plates 124 are attached to the teeth 123 by low-temperature brazing according to the invention, allowing local brazing/de-brazing.

(20) FIG. 6 is an axial sectional view (xx axis) of a cutter 130, for instance a finishing cutter consisting of a hub 131 provided with a bore 132 for its installation on a machine shaft. The hub 131 supports a stack of cutting discs 133-1, 133-2, 133-3 separated by shims 134-1, 134-2 depending on the application, that is, for instance, by the thickness of the plate or the panel to be machined with the cutter.

(21) The discs 133-1, 133-2, 133-3 are similar to the saw discs, provided with peripheral teeth 135, each having a cutting insert 136. Without exception, the discs 131-1, 131-2, 131-3 are identical, locked in rotation about the xx axis and preferably offset angularly with respect to one another about the xx Axis said that this cutter is as balanced as possible in its rotation about its axis.

(22) The assembly formed in this way is locked by interconnecting means that are not shown.

(23) The finishing cutter 130 installed on the machine shaft works only with one cutting disc at a time. The cutter is positioned so that the cutting disc is brought into the active position by the movement of the shaft along the xx axis. Once the plates 136 of the cutting disc (133-n) become worn, the shaft is moved longitudinally along its xx axis by one increment to position another disc 133-n in the appropriate position and work with this disc and so on, until all the discs (or their cutting inserts) are worn. Only at this time is the cutter replaced by a new sharpened cutter.

(24) FIG. 7 shows another tool 140, such as a tearing tool 140, similar to a circular saw disc. This tool 140 has a body 141 with an assembly hole 142 and rotation locking holes 143. The perimeter of the body includes a great number of teeth 144 provided with two series of cutting plates 145a, 145b of different sizes.

(25) These cutting plates 145a, 145b are attached to the teeth 144 by low-temperature brazing for soliciting not only the production but also the repair of damaged or removed teeth, for their replacement by new plates.

(26) FIG. 8 is a plan view of a routing cutter 150 consisting of a body 151 with three teeth 152 each provided with a cutting insert 153 attached by a low-temperature brazing.

(27) To summarize, FIGS. 5 to 8 are a schematic representation of the cutting tool which, according to the invention, is a circular saw blade 120, a grooving blade, a finishing cutter 130, a tearing tool 140, a routing cutter 150, a borehole milling tool, a shank milling tool, a drill bit, or any other tool for working wood or composite materials by the removal of matter.

(28) The same cutting tool may include several plates, also called inserts, brazed onto the body of the tool at angles and in positions specific to the application of the tool. The same cutting tool may include plates or inserts 1, 1 of different compositions or different sizes as shown in FIG. 7 and which may all be brazed onto tool body 141 during the same step, or during two successive brazing steps. In this case, initial brazing is at a temperature suited to an insert of a given composition whereas the second brazing is at a temperature adapted to an insert having another composition, the second temperature being lower than the first in order not to deteriorate the previous brazing.

(29) FIGS. 9 to 11 show the various stages for the production of a cutting insert 1, 1 for a metal tool body designed to be mounted to a machine and at least one cutting insert integral with the tool body.

(30) For the description of the process the steps of which are schematized in FIGS. 9 to 11, reference will also be made to the highly simplified FIGS. 1 to 3 for the structural components of the cutting insert 1, 1. The numerical references of these components will be reused, followed by the suffix A for the purpose of the description without these references all being entered into the FIGS. 9 to 11.

(31) Accordingly, the metal plate of the substrate will bear reference 11A, the ceramic plate will bear reference 14A, the high-temperature brazing alloy will bear reference 12A, the first metallizing layer will bear reference 13A and the second metallizing layer will bear reference 15A. The various parts will have the suffix A assigned to their reference because they are composition components subsequently found in the cutting inserts 1, 1. These plates are also called inserts because the cutting plates are attached to tool body 101 by brazing 16.

(32) In a first step a) (FIG. 9), we use a ceramic plate 14A and a metal substrate plate 11A of substantially the same size.

(33) The ceramic plate 14A is preferably made with at least one ceramic oxide grade chosen from the family of ceramic grades including alumina -Al.sub.2O.sub.3, and zirconia-yttria 3Y-ZrO.sub.2 or a mixture of such ceramic oxide grades.

(34) The metal substrate plate 11A is preferably made of a material chosen from tungsten carbide and steel and more particularly tungsten carbide WCCo and nickel steel C45.

(35) The ceramic plate 14A and the metal substrate plate 11A each preferably thickness included between 0.5 and 5 mm and even more preferably thickness of approximately 3 mm.

(36) During a second step b), a coat of metal material is deposited between the ceramic plate 21 and a first brazing alloy which will be used during a subsequent brazing stage c). This coat of metal material is deposited on at least one of the surfaces in contact during step c).

(37) Similarly, during the second step b). A coat of metal material is deposited between the metal substrate plate 11A and the first brazing alloy 15A.

(38) This coat of metal material is deposited on at least one of the surfaces in contact during step c).

(39) These metallization codes provide a better bond with the brazing alloy for the ceramic plate 14A and for the metal substrate plate 11A.

(40) The deposit of this metal material, preferably in the form of a paint, is performed by all known means.

(41) According to an alternate implementation, during the second step b), the ceramic plate 14A is lined on one of its faces 6 with a coat of metal material to carry out metallization as on one of the faces of the metal substrate plate 11A.

(42) According to another alternate implementation, for a brazing alloy used in the form of a metal sheet, during the second step b) this brazing alloy sheet is lined on its two faces with a coat of metal material for metallization purposes.

(43) According to another alternative, if the brazing alloy used during the brazing of the third step consists of a metal sheet, in the course of the second step b), this brazing alloy sheet may be aligned on one face with a coat of metal material for metallization purposes while the ceramic plate 14A or the metal substrate plate 11A designed to be in contact with the non-metallized face of the said brazing alloy sheet can also be lined on one of its faces or with a coat of metal material.

(44) During a third step shown in the FIG. 10, the ceramic plate 14A is attached to the substrate plate 11A by vacuum brazing and at high temperature. This brazing is carried out by means of a high-temperature brazing alloy 15A, for instance a silver-copper alloy preferably comprising more than 50% of silver by volume, or a silver-indium-titanium based alloy. High-temperature vacuum brazing is carried out, for instance, at a temperature included between 760 C. and 820 C.

(45) During a fourth step shown in the FIG. 11, from assembly 20 obtained in this way, a cutting insert 1, 1 is cut out, covered by the substrate 11 on all of one of its faces. The cutting is carried out by means of a jet of water under pressure, a laser or a diamond disk.

(46) During an intermediate step, the plate 1,1 is ground by the removal of matter, in particular to sharpen the cutting insert, set an angle of inclination on the upper face of ceramic plate 14, and/or reduce at least one dimension of plate 1, 1. After grinding, the plate 1, 1 thickness is preferably between 0.5 and 5 millimetres, and more preferably, approximately 3 millimetres.

(47) During a fifth step shown in FIG. 11, the plate 1, 1 is attached to the tool body 101 by atmospheric pressure brazing at low temperature to make substrate 11 integral with tool body 101. Brazing is carried out using a low-temperature brazing alloy, for instance a silver-copper alloy comprising preferably less than 60% silver by volume, at atmospheric pressure and low temperature, for instance included between 560 C. and 620 C.

(48) In the field of brazing, a temperature of less than 650 C. is considered low and a temperature of more than 750 C. is considered high.

(49) This operation does not require the prior metallizing of the surfaces to be braised but brazing flux can be used to process the corresponding faces before brazing at atmospheric pressure. Indeed, habitually, the tool body 101 is, for instance, based on steel 16MnCr5 or steel C45, that is liable to oxidize, detrimental to the brazing process. The fine coat of oxide can be removed by brazing before filing and the application of a flux: This stripper can be applied by swabbing.

(50) In a last possible step, the manufacturing of a cutting tool 100 involves the mechanical sharpening of the cutting inserts 1, 1 attached to tool body 101, using for instance an abrasive grinder.

(51) The invention also concerns the process for repairing a cutting tool 100, obtained according to the previously described production method.

(52) This repair method consists initially in locally heating, at atmospheric pressure, the tool 100 to destroy the brazing 16 between the substrate 11 of deteriorated cutting insert 1, 1, and tool body 102, then attaching a new cutting insert 1, 1 to the tool body 102 by local brazing at atmospheric pressure and at low temperature. Low-temperature brazing alloy 16 is used to make substrate 11 of the new cutting insert 1, 1 integral with the tool body 102.

(53) Preferably, the local heating of cutting tool 100 is carried out by electromagnetic induction.

(54) As an illustration, examples of the implementation of production methods of a cutting tool 100 according to the invention are given below:

Example 1

(55) A ceramic plate consisting of 100% alumina -Al.sub.2O.sub.3 is lined on one face with a coat of metal paint.

(56) A tungsten carbide metal plate WCCo with at least 30% of Co measuring the same size is also lined on one side with a coat of metal paint.

(57) The metallized face of the ceramic plate is then attached in vacuum and at 810 C. to the metallized face of the tungsten carbide metal plate by a brazing operation. This brazing is carried out using a silver-copper filler alloy comprising more than 50% silver and in particular 72% of Ag by volume.

(58) The assembly obtained in this way is then cut into cutting inserts by means of a jet of water under pressure, a laser or a diamond disk.

(59) Inserts each having a cutting insert are then attached together by their substrate to the tool body by brazing at atmospheric pressure and at a temperature included between 560 C. and 620 C. This brazing is carried out using an electromagnetic inductor and a silver-copper brazing alloy comprising less than 60% silver by volume.

Example 2

(60) A ceramic plate consisting of 100% zirconia-yttria 3Y-ZrO.sub.2 is lined on one face with a coat of metal paint.

(61) A metal plate of nickel steel C45 of the same size is also lined on one face with a coat of metal paint.

(62) The metallized face of the ceramic plate is then attached in vacuum at 780 C. to the metallized face of the metal tungsten plate by brazing using a silver-copper alloy comprising more than 50% silver by volume.

(63) The assembly obtained in this way is then cut into cutting inserts by means of a jet of water under pressure, a laser or a diamond disk.

(64) Inserts each having a cutting insert are then attached together by their substrate to the tool body by brazing at atmospheric pressure and at a temperature included between 560 C. and 620 C. This brazing is carried out using an electromagnetic inductor and a silver-copper brazing alloy comprising less than 60% silver by volume.

Example 3

(65) A ceramic plate is used comprising 90% alumina -Al.sub.2O.sub.3 and 10% zirconium ZrO2 wind on one of its faces with a coat of metal paint and a metal tungsten plate WC-30Co of the same size with a coat of metal paint on one face.

(66) The metallized face of the ceramic plate is then attached in vacuum at 800 C. to the metallized face of the metal tungsten plate by brazing using a silver-copper alloy comprising more than 50% silver by volume.

(67) The assembly obtained in this way is then cut into cutting inserts by means of a jet of water under pressure, a laser or a diamond disk.

(68) Inserts each having a cutting insert are then attached together by their substrate to the tool body by brazing at atmospheric pressure and at a temperature included between 560 C. and 620 C. This brazing is carried out using an electromagnetic inductor and a silver-copper brazing alloy comprising less than 60% silver by volume.

NOMENCLATURE

(69) 1 Cutting insert 1 a Unsharpened surface 1b Unsharpened surface 11 Metal substrate 11 a Brazing surface 11b Attaching surface 12 High temperature brazing alloy 13 Metal layer 15 Metal layer 16 High temperature brazing alloy 11A Metal plate 12A High temperature brazing alloy sheet 13A Metal layer 14A Ceramic plate 15A Metal layer 20 Assembly 100 Cutting tool 101 Tool body 102 Location of cutting insert 1, 1 110 Cutter 111 Body 112 Cutting insert 120 Circular saw disk 121 Body 122 Attaching hole 123 Peripheral tooth 124 Cutting insert 130 Finishing cutter 131 Hub 132 Bore 133_1, 133_2, 133_2, Cutting disks 134_1, 134_2, Shims 135 Peripheral tooth 136 Cutting insert 140 Tearing tool 141 Body 142 Assembly hole 143 Rotation locking hole 144 Tooth 145a, 145b Cutting plates 150 Routing cutter 151 Body 152 Tooth 153 Cutting insert D Thickness direction of cutting insert H1 Working height xx Tool axis