The present invention relates to a spare blade of a cutter for rotary cutting to be used in a cutting process using a tenoner or a moulder, or a cutting process before bonding an edging strip by an edge bander, when a furniture component, etc. is produced by using a particle board, a medium density fiberboard (MDF), a solid wood board, etc., and also relates to a cutter using such a spare blade.
Conventionally, for example, as shown in
Meanwhile, a cutter employing polycrystalline diamond (hereinafter referred to as PCD) as a material of the aforementioned spare blades to be attached to a cutter for rotary cutting in order to secure durability is known, for example, as described in Patent Document 2. However, when the cutter employs PCD spare blades and the spare blades are reground, it is often difficult to keep outer diameters of cutting edges constant or it takes a lot of effort to make adjustment to keep the external dimensions constant, or tedious diameter correction is necessary on a side of a cutting machine. Besides, because of use of an expensive PCD material, such PCD spare blades are expensive.
[PTL 1] Japanese Unexamined Utility Model Application Publication No. S62-113,915
[PTL 2] Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2013-517,952
The present invention has been made to solve these problems. It is an object of the present invention to provide a spare blade of a cutter for rotary cutting capable of reducing height differences in boundaries between a plurality of spare blades when attached to a body of the cutter by simple processing and also capable of having improved durability while using an inexpensive cutting edge material, and a cutter using such a spare blade.
In order to attain the above object, the present invention has the following features: In a spare blade for cutting formed of a hard cutting edge material, having a shape of a plate-like polygon, and to be attached to an outer circumferential surface of a cutter for forming a plane by rotary cutting, a flank surface forming cutting edges is a convex surface bulging in a shape of a lateral surface of a single cone and a center of the polygon lies on an axis of the convex surface. The shape of the lateral surface of the single cone is not limited to a shape of an entire lateral surface of a single cone. Examples of the hard cutting edge material include cemented carbide, tool steel, cermet, PCD, and cubic boron nitride (CBN).
In the present invention having the above constitution, a flank surface forming cutting edges of a spare blade to be attached to an outer circumferential surface of a cutter is a convex surface slightly bulging in a shape of a lateral surface of a single cone. Therefore, the respective cutting edges of the polygon have curves and height differences in boundaries between such spare blades when the spare blades are attached to a body of the cutter can be reduced. As a result, lines are suppressed from occurring on a cut surface of a workpiece in the present invention. Moreover, machining to form such a flank surface of the spare blade, i.e., formation of a conical convex surface can be easily done by a single grinding operation in a shape of a cone along an outer peripheral portion with a center of the polygon on an axis of the cone. As a result, grinding in the present invention can be carried out by a simple operation in a short time when compared to conventional grinding of side surfaces to form curves, so spare blades can be provided at a low cost. Furthermore, since the spare blade of the present invention can have flat side surfaces, the spare blade is not displaced from a spare blade reference plane by screw fastening when attached to a body. Therefore, attachment of the spare blade is easy and does not produce harmful height differences between spare blades.
In addition, in the present invention, preferably the cutting edge material is cemented carbide or cermet, and an entire surface of the cutter spare blade is covered with a hard coating film having a thickness of 1 to 25 μm. More preferably, the hard coating film is formed of chromium nitride, chromium oxide, chromium oxynitride, diamond, diamond-like carbon (DLC) or the like. Furthermore, preferably, diamond is CVD diamond formed by chemical vapor deposition (CVD). Owing to the hard coating film, even a spare blade formed of cemented carbide or cermet can attain improved durability.
Moreover, the present invention can be a cutter having the cutter spare blade recited in any one of claims 1 to 3 attached thereto and forming a face bevel angle of 20 deg. or more. In a case of a cutter using a plurality of spare blades of the present invention, upon thus increasing face bevel angles of the spare blades to 20 deg. or more, height differences in boundaries between the spare blades can be reduced and accordingly differences in an outer diameter of the cutter can be reduced when compared to in a case of a conventional cutter. As a result, in a case of cutting with great face bevel angles in the present invention, lines can be suppressed from occurring on a cut surface of a workpiece.
In the present invention, a flank surface of a spare blade is a convex surface slightly bulging in a shape of a lateral surface of a single cone. Therefore, height differences in boundaries between spare blades when the spare blades are attached to a body of a cutter can be reliably reduced at a low cost. Moreover, in the present invention, cutting edges formed of an inexpensive material such as cemented carbide or cermet are coated with diamond. Therefore, durability of spare blades can be improved at a low cost.
Hereinafter, an example of the present invention will be described with reference to the drawings.
On a right end side of the body 11, mounting seats 13 are provided at three positions at equal circumferential intervals so as to extend over the outer circumference surface 11a and the bevel portion 11e. The mounting seats 13 sink at an inclination angle of about 10 deg. in an opposite direction to a rotation direction R and are inclined in an inward direction at an angle of 45 deg. with respect to an axial direction. Provided ahead in a rotation direction of the mounting seats 13 are chip pockets 14 which dent from the mounting seats 13. Provided behind in the rotation direction of the mounting seats 13 are positioning portions 15 which slightly protrude from the mounting seats 13. On a left end side of the body 11, mounting seats 16 are provided at three positions spaced circumferentially from the aforementioned mounting seats 13 by an angle of 40 deg. so as to extend over the outer circumferential surface 11a and the bevel portion 11d. The mounting seats 16 sink at an inclination angle of about 10 deg. in an opposite direction to the rotation direction R and are inclined in an inward direction at an angle of 45 deg. with respect to the axial direction. That is to say, the inclination of the mounting seats 16 is opposite to that of the mounting seats 13. Provided ahead in the rotation direction of the mounting seats 16 are radially dented chip pockets 17. Provided behind in the rotation direction of the mounting seats 16 are positioning portions 18 which slightly protrude from the mounting seats 16.
On an outer circumferential surface 11a of the body 11, mounting seats 21 are provided at three positions spaced ahead in the rotation direction from the above mounting seats 16 by an angle of 40 deg. The mounting seats 21 are inclined in parallel to the above mounting seats 16. Provided ahead in the rotation direction of the mounting seats 21 are radially dented chip pockets 22. Provided behind in the rotation direction of the mounting seats 21 are positioning portions 23 which slightly protrude from the mounting seats 21. Each of the mounting seats 13, 16 and 21 has a threaded mounting hole, not shown, at its center for fixing a spare blade 25 to be mentioned later.
As shown in
Since the convex portion 28a is formed on the flat face 28 as mentioned above, in the spare blade shown in
In the example having the aforementioned constitution, the flank face forming the cutting edges 29 of the spare blade 25 attached to the outer circumferential surface of the cutter 10 is the convex portion 28a slightly bulging in a shape of a lateral surface of a single cone. Therefore, in the spare blade shown in
Moreover, formation of the convex portion 28a in a cone shape can be easily done by conically grinding an outer periphery once with a center of the square of the spare blade 25 on an axis of the cone. Therefore, machining of the flat face 28 of the spare blade 25 is much easier than conventional machining of the side faces in a curve shape and the spare blade 25 can be provided at a low price. Furthermore, since at least two of the four sides of the spare blade 25 can be used in the present example, use efficiency of the spare blade 25 can be increased. Moreover, since a diamond coating film is formed within a thickness range of 5 to 25 μm on an entire surface of the spare blade 25 in the present example, even a spare blade formed of inexpensive cemented carbide or cermet instead of expensive PCD can attain improved durability. Furthermore, since the side faces serving as the rake faces 27 can be flat, the spare blade 25 of the present example is not dislocated from a reference surface for the spare blade 25 by fastening a screw 33 when the spare blade 25 is attached to the body 11. Therefore, the attachment operation is easy and useless height differences between blades 25 can be prevented from being generated by dislocation in attaching the spare blades 25.
Moreover, in the cutter 10 according to the present example, height differences in boundaries between the spare blades 25 can be reduced even when the face bevel angle of the spare blades 25 is increased to 20 deg. or more. Therefore, even in a case of cutting at a great face bevel angle, lines are suppressed from occurring on a cut surface of a workpiece. Furthermore, the inclination angle of the conical grinding of the spare blade 25 is changed in accordance with a face bevel angle when the spare blade 25 is attached to the body 11, and an outer diameter. The face bevel angle is also changed by whether a laminated material is melamine, paper or the like.
Now, measurement results on a maximum height difference between spare blades when the spare blades are attached at different face bevel angles will be described. Five kinds of spare blades were chosen: one formed by conical grinding (a spare blade according to an example of the present invention), one having straight faces (a conventional spare blade shown in
As shown in
As apparent from Table 1, maximum height differences of the spare blades of the present invention with most appropriate conical grinding angles were much smaller than those of the spare blades with straight faces. The maximum height difference of the spare blades of the present invention with most appropriate conical grinding angles were about as small as that of the spare blade with R150 at a face bevel angle of 30 deg., but much smaller than a maximum height difference of the spare blade with R100 at a face bevel angle of 45 deg. and that of the spare blade with R50 at a face bevel angle of 70 deg. A most appropriate grinding angle of the spare blade is greater with an increase in the face bevel angle.
Next, modified examples of the aforementioned example will be described.
On a right end side of the body 41, two mounting seats 43 and chip pockets 44 and positioning portions 45 ahead of and behind the two mounting seats 43 are provided within ranges of about 48 deg. at three positions at equal circumferential intervals so as to extend from the bevel portion 41e to a middle of an outer circumference surface 41a. The two mounting seats 43 are sequentially arranged in such a manner that cutting edges are inclined at an angle of 70 deg. with respect to an axial direction. On a left end side of the body 41, three mounting seats 46 and chip pockets 47 and positioning portions 48 ahead of and behind the three mounting seats 46 are provided within ranges of about 72 deg. at three positions spaced circumferentially from the aforementioned mounting seats 43 by an angle of about 72 deg. so as to extend from the bevel portion 41d to a middle of the outer circumference surface 41a. The three mounting seats 46 are sequentially arranged in such a manner that cutting edges are inclined at an angle of 70 deg. with respect to the axial direction. Spare blades 25 are fixed on the mounting seats 43, 46 by screws 33 as mentioned above. A face bevel angle of the spare blades 25 attached to the mounting seats 43 and a face bevel angle of the spare blades 25 attached to the mounting seats 46 are 70 deg, and have an opposite sign to each other.
As a result, although the spare blades 25 in the aforementioned example had a face bevel angle of 45 deg. with respect to the axis, the spare blades 25 in the modified example had a face bevel angle of 70 deg. to the axis. Moreover, the inclination angle of the convex portion 28a of the spare blades 25 with respect to the flat face in the modified example is greater than the inclination angle of the convex portion of the spare blades with respect to the flat face in the aforementioned example. Even when this cutter 40 is employed to cut a workpiece which requires cutting using spare blades fixed at a great face bevel angle and a great face bevel angle is set, lines can be suppressed from occurring on a cut surface of the workpiece.
Next, Specific Examples 1, and 3 for testing cutting performance of cutters produced according to the aforementioned example of the present invention will be sequentially described.
A cutting test was performed on a cutter employing spare blades 25 of a specific example of the present invention as Invention Product 1 and a cutter having brazed PCD blades as Comparative Product 1 under cutting conditions 1 shown below.
Spare blade material: cemented carbide, diamond coating (film thickness: 20 μm)
Spare blade dimensions: 15 mm×15 mm×2.5 mm
Spare blade cone inclination angle: 3.66 deg.
Cutter dimensions: outer diameter φ: 125 mm, cutting width: 44 mm, substantial number of blades: 3 pieces
Face bevel angle: 45 deg.
Wedge angle: 60 deg.
Cutting edge material: PCD (brazed)
Cutter dimensions: the same as Invention Product 1
Face bevel angle: 45 deg.
Wedge angle: 60 deg.
Workpiece: melamine laminated particle board (thickness: 15 mm)
Number of cutter rotations: 6000 rpm
Feed rate: 20 m/min
Depth of cut: 0.8 mm
When melamine laminated particle boards were cut by Inventive Product 1 and Comparative Product 1, melamine facing chipping size was measured by a roughness meter and measurement results are shown in a graph in
A cutting test was performed on a cutter employing spare blades of a specific example of the present invention as Invention Product 2 and cutters having brazed PCD spare blades as Comparative Examples 2, 3 under cutting conditions shown below.
Spare blade material: cemented carbide, diamond coating (film thickness: 12 μm)
Spare blade dimensions: 15 mm×15 mm×2.5 mm
Spare blade cone inclination angle: 5.80 deg.
Cutter dimensions: outer diameter φ: 125 mm, cutting width: 44 mm, substantial number of blades: 3 pieces
Face bevel angle: 70 deg.
Wedge angle: 49 deg.
Cutting edge material: PCD (brazed)
Cutter dimensions: the same as Invention Product 2
Face bevel angle: 45 deg.
Wedge angle: 60 deg.
Cutting edge material: PCD (brazed)
Cutter dimensions: the same as Invention Product 2
Face bevel angle: 70 deg.
Wedge angle: 49 deg.
Workpiece: Paper laminated particle board (thickness: 15 mm)
Number of cutter rotations: 6000 rpm
Feed rate: 20 m/min
Depth of cut: 0.8 mm
Fluff size was measured with a microscope when a paper laminated particle board was cut by Invention Product 2 and Comparative Products 2, 3 and measurement results are shown in a graph in
A durability test was performed on cutters 3, 4 employing spare blades of a specific example of the present invention as Invention Products 3, 4 under cutting conditions shown below.
Spare blade material: cemented carbide, diamond coating (film thickness: 12 μm, 20 μm]
Spare blade dimensions: 15 mm×15 mm×2.5 mm
Spare blade cone inclination angle: 5.80 deg.
Cutter dimensions: outer diameter φ: 125 mm, cutting width: 44 mm, substantial number of blades: 3 pieces
Face bevel angle: 70 deg.
Wedge angle: 49 deg.
Workpiece: paper laminated particle board (thickness: 15 mm)
Number of cutter rotations: 6000 rpm
Feed rate: 10 m/min
Depth of cut: 0.5 mm
Total cutting length: 8,000 m
Cutting edges of Invention Products 3, 4 were observed through an electron microscope after cutting paper laminated particle boards for a total cutting length of 8,000 m. Almost no wear was observed on the diamond coatings of the cutting edges and it was found that the spare blades had high wear resistance. Roughness measurement of edge lines of the spare blades revealed that chippings were observed in half of the cutting edges of Invention Product 3 having a thin coating film but no chippings were observed in the cutting edges of Invention Product 4 having a thick coating film.
Fluff height measured with a microscope in initial cutting and after cutting 8,000 m of the boards by Invention Products 3, 4 is shown in a graph in
The spare blades 25 in the aforementioned examples are thin square plates. Instead of the spare blades 25, as shown in
It should be noted that although diamond coating film is formed on the entire surface of the spare blade formed of cemented carbide or cermet in the aforementioned example, chromium nitride, chromium oxynitride, chromium oxide, DLC or the like can be coated instead of diamond. Moreover, the aforementioned examples are just examples and various modifications are possible without departing from the spirit of the present invention.
10 Cutter, 11 Body, 13, 16, 21 Mounting seat, 25 Spare blade, 27 Rake face, 28 Flat face, 28a Convex portion, 40 Cutter, 41 Body, 43, 46 Mounting seat
Number | Date | Country | Kind |
---|---|---|---|
2013-179787 | Aug 2013 | JP | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/JP2014/004431 | 8/28/2014 | WO | 00 |