WO2009113734A1

WO2009113734A1 - Cutter and cutting machine

Info

Publication number: WO2009113734A1
Application number: PCT/JP2009/055542
Authority: WO
Inventors: Satsuo Satou; Shinki Ohtsu; Toshihiro Ichijyou; Junichi Kamimura; Naoki Omata
Original assignee: Hitachi Koki Co., Ltd.
Priority date: 2008-03-14
Filing date: 2009-03-13
Publication date: 2009-09-17
Also published as: JP2009220212A; JP5339178B2

Abstract

A rotatable cutter comprises a base plate 2 and a chip 4 fixed on the base plate 2. The chip comprises an abrasive grain layer containing abrasive grains 10, a joining layer joining the abrasive grain layer to the base plate 2, and a metal sheet 9 provided across the joining layer and abrasive grain layer in the radial direction of the base plate 2. Metal sheet 9 reinforces binding inside abrasive grain layer and joining layer respectively, and has a plurality of exposure pores 15 through which abrasive grains 10 are exposed. Exposure pores 15 are arranged to cross without fail an arbitrary circumferential line that runs along chip circumference about center axis of the base plate 2. The metal sheet 9 exercises no influence by having this arrangement on distribution of abrasive grains 10 made of diamond, etc. in the abrasive grain layer, and firmly binds the joining layer and abrasive grain layer internally, and the joining layer to the base plate 2.

Description

DESCRIPTION

Title of the Invention CUTTER AND CUTTING MACHINE

Technical Field

[0001] The present invention relates to a cutter having cutting abrasive grains, and a cutting machine including the cutter.

Background Art [0002] Cutters that include abrasive grains and metallic particles are used as blades of cutting machines that cut work materials such as concrete, mortar, ceramic, stone materials, etc.

Cutters are constituted by a base plate that rotates as energized by an electric motor, and a chip joined to the outer circumference of the base plate. The center portion of the base plate is rotatably mounted on the cutting machine.

The chip is formed as a result of sintering an annular abrasive grain layer and an annular joining layer provided on the inner circumference of the abrasive grain layer. The abrasive grain layer includes abrasive grains, mainly diamond, that are bonded to bond (bonding agent) that contains particles of metals such as W, Cu, Ni, Co, Sn, Ag, etc., and serves as a cutting member.

The joining layer joins the base plate and the abrasive grain layer together. For example, the joining layer of the cutter disclosed in Patent Literature 1 is made of a complex alloy that contains titanium. This composition increases the joining strength between the base plate and the chip, and as result, improves the cutting performance of the cutter.

[0003] The cutting performance of a cutter depends on the thickness and shape of the cutting blade, the grain size and content of the cutting abrasive grains, and the wear characteristic and strength characteristic of the bond that immobilizes the cutting abrasive grains.

Since cutting works produce powder dust and noises, cutter users demand cutters that can cut work materials efficiently in a short time. To meet this demand, cutters that include a thin chip and cut a small area are under development.

[0004] Patent Literature 1 : Unexamined Japanese Patent Application KOKAI Publication No. H10-166275

Summary of Invention [0005] However, a chip will have a lower strength if formed thinner and might break during cutting. Furthermore, it has been difficult to increase the joining strength between the chip and the base plate. Hence, it has been difficult to manufacture a thin chip that has a high strength and a high joining strength for it to be joined with a base plate. [0006] The present invention was made in view of the above circumstances, and an object of the present invention is to provide a cutter having a high cutting performance by including a thin chip that has endurance against breakage and a high joining strength for itself to be joined with a base plate, and a cutting machine including the cutter.

[0007] Another object of the present invention is to provide a cutter including a chip in which an abrasive grain layer and a joining layer are joined firmly, and a cutting machine including the cutter.

[0008] Of the inventions disclosed herein, representative ones have the following characteristics.

[0009] A cutter according to a first aspect of the present invention comprises: a base plate; and a cutting member that is fixed on a circumferential surface of the base plate, and cuts a work material by rotating together with the base plate, characterized in that the cutting member comprises: an abrasive grain layer that contains abrasive grains and bits the work material; a joining layer that joins the circumferential surface of the base plate to the abrasive grain layer; and a reinforcing member that is provided over an interior of the joining layer and an interior of the abrasive grain layer to reinforce binding inside the abrasive grain layer and binding inside the joining layer.

[0010] A cutting machine according to a second aspect of the present invention comprises: a body; a drive source; and a cutter including a base plate that is rotatably driven by the drive source, and a cutting member that is fixed on a circumferential surface of the base plate and cuts a work material, characterized in that the cutting member comprises: an abrasive grain layer that contains abrasive grains and hits the work material; a joining layer that joins the circumferential surface of the base plate to the abrasive grain layer; and a reinforcing member that is arranged over an interior of the joining layer and an interior of the abrasive grain layer to reinforce binding inside the abrasive grain layer and binding inside the joining layer.

[0011] The cutter and the cutting machine according to the present invention include a reinforcing member that is provided to straddle both the joining layer and the abrasive grain layer. Therefore, the joining layer and the abrasive grain layer are firmly joined and crack development can be stopped. Further, the cutter and the cutting machine according to the present invention can use a thin chip with a smaller cutting resistance, thereby can achieve a high-speed cutting performance. Brief Description of Drawings [0012] Fig. 1 is a front elevation of a cutting machine according to an embodiment.

Fig. 2 is a front elevation of a cutter according to an embodiment. Fig. 3 is a cross sectional view of a chip including a metal sheet according to a first embodiment, taken along a line A-A shown in Fig. 2.

Fig. 4 is a cross sectional view of the chip including the metal sheet according to the first embodiment, taken along a line B-B shown in Fig. 3.

Fig. 5 is an exemplary cross sectional view for explaining a relationship between exposure pores of the metal sheet and the cutting edge.

Fig. 6A is a diagram showing the shape of the metal sheet according to the first embodiment, and Fig. 6B is a diagram showing the shape of a metal sheet according to a second embodiment.

Fig. 7 is a cross sectional view of a chip including a metal mesh according to a third embodiment.

Figs. 8A to 8D are cross sectional views of chips including metal meshes according to the third embodiment, taken along the line A-A shown in Fig. 2.

Fig. 9 is a diagram showing a cutter that comprises a base plate of a different type from the base plate shown in Fig. 2.

Description of Embodiments

[0013] A cutter and a cutting machine according to an embodiment of the present invention will be explained below with reference to the attached drawings. [0014] A cutting machine 40 according to the present embodiment is used for cutting and grinding a work material 50, which may be concrete, mortar, ceramic, stone materials, etc.

As shown in Fig. 1, the cutting machine 40 is constituted mainly by an electric motor (drive source) 41, a body 42 in which the electric motor 41 is housed, and a cutter 1 supported by the body 42 and connected to an output shaft 44 of the electric motor 41.

A handle 46 grabbed by a worker is formed on a portion of the body 42. The body 42 has a switch 48 near the handle 46. The electric motor 41 is supplied with power from an electric outlet, a battery, or the like. The switch 48 is connected to the power supply path leading to an electric outlet, a battery, or the like, and when operated, switches on/off the power supply to the electric motor 41. [0015]

<First Embodiment Next, the cutter 1 having a metal sheet 9 according to a first embodiment will be explained with reference to Fig. 2 to Fig. 4 and Fig. 6A. As shown in Fig. 2, the cutter 1 is constituted by a disk-like base plate 2 that rotates by motive energy of the electric motor 41 (see Fig. 1), and a chip (cutting member) 4 joined to the outer circumference of the base plate 2. The base plate 2 is made of steel or the like that is heat-treated. An attachment hole 3 that can fit the output shaft 44 of the electric motor 41 is formed in the center of the base plate 2.

The chip 4 is constituted by an abrasive grain layer 5, which contains abrasive grains 10 immobilized by bond (bonding agent) to form an annular- shaped layer, a joining layer 6 provided on the inner circumference of the abrasive grain layer 5 and having an annular shape, and a metal sheet (reinforcing member) 9 provided in the thickness- wise direction of the abrasive grain layer 5 and the joining layer 6.

As shown in Fig. 3, the abrasive grain layer 5 is made of hard abrasive grains 10, which are mainly diamond, and bond, which contains metal particles of W, Cu, Ni, Co, Sn, Ag, etc., where the grains and the bond are bonded together and sintered.

The joining layer 6 is made of a metal that can suitably be welded to the base plate 2, and welded to the outer circumference of the base plate 2 by laser or the like. A joint 7 is produced as the result of the welding. The abrasive grain layer 5 and the joining layer 6 are joined together and sintered and formed into shape. [0016] The metal sheet (reinforcing member) 9 improves the binding forces inside the abrasive grain layer 5 and inside the joining layer 6 respectively. The metal sheet 9 is provided inside the chip 4 over the interior of the joining layer 6 and the interior of the abrasive grain layer 5. The metal sheet 9 produces internal binding forces in the abrasive grain layer 5 and the joining layer 6 respectively to bind together the portions of the abrasive grain layer 5 that are on the opposite sides of the metal sheet 9 and the portions of the joining layer 6 that are on the opposite sides of the metal sheet 9, such that the abrasive grain layer 5 and the joining layer 6 adjoin each other in the radial direction. The metal sheet 9 is a smelted material, and preferably provided near the center of the chip 4 in its thickness-wise direction. A surface of the work material 50 (see Fig. 1) that is to be cut needs to have substantially the same coarseness at their portions that contact the abrasive grain layer 5 and at their portions that contact the metal sheet 9. Hence, as shown in Fig. 4, which shows a cross section of Fig. 3 taken along a line B-B, the metal sheet 9 has exposure pores 15 through which the abrasive grains 10 contained in the abrasive grain layer 5 are exposed on the outer circumferential surface 22. The exposure pores (empty holes) 15 penetrate the metal sheet 9 in the thickness- wise direction, are provided in a plural number in the circumferential direction, and have a flat circular shape. These exposure pores 15 serve to connect each of the grain layers 5 and each of the joining layers 6. Here, for explanation, the grains 10 (e.g. diamonds) are depicted larger than in the actual proportion to the exposure pours 15: therefore this does not depict a scaled model. [0017] Next, the process for shaping the chip 4 will be explained. The abrasive grain layer 5 and the joining layer 6 are disposed. Then, the metal sheet 9 is placed on the abrasive grain layer 5 and the joining layer 6. On the metal sheet 9, another abrasive grain layer 5 and another joining layer 6 are disposed to fix the metal layer 9 at the center of the chip 4 in its thickness-wise direction. The metal sheet 9, the grain layer 5 and the joining layer 6 are compressed and then sintered, to obtain the chip 4. After this, the joining layer 6 of the chip 4 is welded to the base plate 2, thereby the cutter 1 is formed.

A problem of this formation is that the metal sheet 9 will not have a different cubic volume after being compressed, because it is a smelted material. Hence, the portions of the abrasive grain layer 5 that contact the metal sheet 9 will have an increase in density, but the portions of the abrasive grain layer 5 that contact the exposure pores 15 of the metal sheet 9 will have no increase in the density. Accordingly, the chip 4 is formed to have unevenness in the density and cannot have a sufficient strength. [0018] The inventor has paid an attention to this point, and to achieve a uniform cutting performance constantly, has arranged the plurality of exposure pores 15 of the metal sheet 9 such that they cross without fail any arbitrary circumferential line that runs along the circumference of the chip 4 about the central axis of the base plate 2, and has placed the abrasive grains 10 at the cross-points. The details will be described later. [0019] The cutter 1 cuts the work material 50 mainly by the abrasive grains 10, which protrude from the outer circumferential surface 22 (the abrasive grains 10a that are exposed outside, shown in Fig. 3 and Fig. 4), cutting the work material 50. Hence, it is important that the cutter 1 should always have some abrasive grains 10 protruding from the outer circumferential surface 22, which is the cutting edge of the cutter 1. The cutter 1 gradually galls and has its outer diameter reduced as a cutting work goes on. For example, consider a case shown in Fig. 4, where the outer circumferential surface 22 has come to the position of a two-dot chain line 21 by galling. In this case, if there are any abrasive grains 10 that cross the two-dot chain line 21, the outer circumferential surface 22 has got some abrasive grains 10 to protrude therefrom and can serve as a cutting portion. If there are no abrasive grains 10 that cross the two-dot chain line 21, the cutter 1 cannot have a high cutting performance and serve its function, and should be replaced by another cutter. [0020] Relationship between exposure pores 15a of a metal sheet 9a and a cutting edge will be explained with reference to Fig. 5. Fig. 5 does not show abrasive grains 10 in the exposure pores 15a, but the abrasive grains 10 are actually provided just the same as in Fig. 4. Further, Fig. 5 shows a case that the exposure pores 15a have the shape of a perfect circle.

The outer circumferential surface 22 of the metal sheet 9a gradually galls along with the use of the cutter 1. Consider a case that the outer circumferential surface 22 changes its position to two-dot chain lines 21a, 21b, 21c, ... by galling. When the outer circumferential surface 22 is positioned at the two-dot chain line 21a or at the two-dot chain line 21b, the exposure pores 15a are exposed on the outer circumferential surface 22. Thus, abrasive grains 10 of the grain layer 5 that exist inside the exposure pores 15a are exposed and serve the cutting function. When the outer circumferential surface 22 is positioned at the two-dot chain line 21c, no exposure pores 15a are exposed on the outer circumferential surface 22 and no abrasive grains 10 are exposed. Hence, the cutting performance is low until the metal sheet 9a wears away by galling to expose some exposure pores 15a from which abrasive grains 10 protrude. Frictional heat that might be generated between the metal sheet 9a and the work material 50 might melt some part of the bond of the abrasive grain layer 5 or carbonize diamond, which may be used as the abrasive grains 10, and would greatly shorten the product life of the cutter. [0021] For the reasons described above, regardless of deepening of the galling of the cutter 1, it is critical that abrasive grains 10 be always exposed from the outer circumferential surface 22 until a prescribed final use position. Hence, the metal sheet 9 has exposure pores 15 that are so distributed as to be always exposed on the outer circumferential surface 22 until the final use position is reached. [0022] The shape of metal sheets 9 and 9b that have exposure pores 15 and 15b that are provided to cross without fail an arbitrary circumferential line that runs along the circumference of the chip 4 about the central axis of the base plate 2 will be explained with reference to Fig. 6A.

[0023] Fig. 6A is a diagram that shows the metal sheet 9 shown in Fig. 4 in enlargement. The metal sheet 9 has flat-circular exposure pores 15 each formed of two semicircles combined by a straight line. The exposure pores 15 are staggered on the circumferential lines.

For example, as shown in Fig. 6A, assume that the length of the longer diameter of one exposure pore 15 is "L", and the length over which this exposure pore 15 overlaps the longer diameter of an exposure pore 15 that adjoins this exposure pore 15 is "Ll". The overlapping length Ll accounts for 25 to 35% of the length L of the longer diameter of the one exposure pore 15. If this rate lowers to less than 25%, a circumferential surface having few exposure pores 15 emerges, and few abrasive grains 10 are exposed from the outer circumferential surface 22, which reduces the cutting performance of the cutter 1. By giving the metal sheet 9 a shape that enables the exposure pores 15 to exist on all circumferences at the same level, it is possible to achieve a generally uniform distribution of the abrasive grains 10 that exist in the exposure pores 15. [0024]

<Second Embodiment

The metal sheet 9b according to a second embodiment has oval exposure pores 15b as shown in Fig. 6B. The exposure pores 15b are distributed on the circumferential lines running about the center of the base plate 2, in a so-called staggered pattern in which the exposure pores 15b meet each other only by about their halves, in a similar manner to the distribution shown in Fig. 6A.

[0025] In both the examples shown in Fig. 6A and Fig. 6B, the exposure pores 15 and 15b are distributed in a staggered pattern. That is, the exposure pores 15 and 15b formed in the metal sheets 9 and 9b cross without fail an arbitrary circumferential line that runs along the circumference of the chip 4 about the attachment hole 3.

If an arbitrary circumferential line that runs along the circumference of the chip 4 has any portion at which the circumferential line crosses no exposure pore 15 or 15b, no abrasive grains 10 (see Fig. 4) are exposed from such a portion to lower the cutting performance and fluctuate the cutting speed. Hence, it is desired that adjoining exposure pores 15 or 15b be shaped and distributed to overlap each other on one circumferential line that runs about the attachment hole 3.

[0026] In Fig. 6A and Fig. 6B, it has been explained that the exposure pores 15 and 15b have a flat-circular shape and an oval shape respectively. However, the exposure pores are not limited to these shapes, and may have shapes of various types of circles or a squared shape, or any ones of these shapes in combination. The shape may be determined based on how easy it is to form the shape, or an arbitrary shape that is produced by a shaping method that utilizes corrosion may be used. The exposure pores 15 may have a squared shape, but it is desired that the corners of the squared shape be given a curvature in order not to tear the metal sheet 9 when applied a pressure of a die or a mold for shaping or sintering. [0027] Next, the materials of the metal sheets 9 and 9b will be explained. The metal sheets 9 and 9b contain Cu as the main component, which accounts for 95% or higher of the whole content, and any of Sn, Ni, P, Mn, and Fe or instead any of them plus an impurity element, which account(s) for 5% or lower of the whole content. [0028] A cutter 1 that is mainly used for machining cement primarily uses diamond as the abrasive grains 10. The bond in the chip 4 for bonding such abrasive grains 10 contains mixture particles of metals such as Ni, Cu, Fe, W, Sn, Ag, etc. and is sintered together with the abrasive grains 10 at a temperature of 700 to 900 degrees C. Hence, Cu or any Cu alloy mentioned above is the most suitable as the metal to be diffusion-bonded to these metals under such conditions, and such an alloy needs to have a composition that does not cause the alloy to melt. It is possible to achieve a similar effect with a steel sheet mainly made of Fe, which is fully annealed and plated. In this case, it is desired that the plated material peel little and have little unevenness. [0029] The thickness of the metal sheets 9 and 9b is 15 to 30% of the thickness of the chip 4. This is because if the thickness of the metal sheets 9 and 9b is lower than 15% of the thickness of the chip 4, the material properties of the bond component of the abrasive grain layer 5 become dominant and it becomes harder for the metal sheets 9 and 9b to demonstrate their effect, and because the less effective metal sheets 9 and 9b weaken the binding strength in the bond in the abrasive grain layer 5 to make the layer 5 liable to tear or cannot deter crack development, in a case where, for example, the chip 4 is formed and sintered into a different shape.

The reason for which the thickness of the metal sheets 9 and 9b is 30% or lower of the thickness of the chip 4 is to suppress the above-described density difference between the portions of the abrasive grain layer 5 that contact the metal sheets 9 and 9b and the portions of the abrasive grain layer 5 that contact the exposure pores 15 and 15b. Another reason is that if Cu layer, which is the main component of the metal sheets 9 and 9b, emerges in a greater amount to the outer circumferential surface 22, it generates heat by friction with the work material 50 to cause the metal sheets 9 and 9b to plastically flow and coat nearby abrasive grains 10, which worsens the cutting ability of the cutter 1. This phenomenon tends to occur in a cutting work that is particularly hard and heavy. It is therefore desirable to avoid giving the metal sheets 9 and 9b a thickness that exceeds 30% of the thickness of the chip 4. [0030] Further, the rate at which the exposure pores 15 and 15b cross a circumferential line that runs along the circumference of the chip 4 about the attachment hole 3 of the base plate 2 (hereinafter, this rate will be referred to as porosity) is 35 to 80% of the circumferential line.

The porosity is set to 35% or higher in order to securely expose the abrasive grains 10 from the outer circumferential surface 22 that serves as the cutting edge. The abrasive grains 10 in the abrasive grain layer 5 are exposed in the exposure pores 15 and 15b while the chip 4 is shaped. A region of the metal sheets 9 and 9b that adjoins the outer circumferential surface 22 of the chip 4 best contributes to cutting. Hence, in order to increase the cutting performance of the cutter 1, it is necessary to allocate abrasive grains 10 in this region. In contrast, if the porosity is lower than 35%, the exposure pores 15 and 15b can only have a small area to let the abrasive grains 10 in. As a result, fewer abrasive grains 10 are exposed from the outer circumferential surface 22 and the cutting performance of the chip 4 is reduced.

If the porosity is over 80%, space occupation of the metal sheets 9 and 9b is very small. Then, if a crack occurs in the bond in the abrasive grain layer 5, the metal sheets 9 and 9b can hardly stop the development of the crack. Further, the metal sheets 9 and 9b have a reduced strength and are liable to tear during shaping and sintering.

Furthermore, in a case where a chip in which a groove is formed in the thickness-wise direction is employed, the probability that the chip may break during shaping is high with such a highly porous metal sheet, which is not desirable. [0031] An appropriate range of the porosity varies according to the material and hardness of the metal sheets 9 and 9b and the work material 50 machined. In an example experiment conducted by the inventor, in which the cutter 1 is for cutting concrete and the chip 4 of the cutter 1 includes the metal sheet 9b, whose thickness is 0.2 to 0.3 mm and whose main component is Cu, and which includes oval exposure pores 15b, the appropriate range of the porosity was 48 to 72%. [0032] The inventor discovered that particularly a chip 4, whose cross sectional shape is not uniform, and which includes a metal sheet 9 or 9b made of an Fe-based steel material, tends to get the metal sheet 9 or 9b detached from the bond in the chip 4 due to a spring back of the metal sheet 9 or 9b during shaping of the chip 4. The inventor further discovered that this chip 4 cannot have intermetallic diffusion occur between the metals contained therein during sintering of the chip 4 and thus cannot have a strong cohesiveness, and as a result cannot have a sufficient strength. These phenomena are more remarkable if a cutter includes a base plate 2 that is partially surrounded by the layers of the chip 4 and as the base plate 2 is thicker. The inventor also discovered that surface treatment such as plating is required as a measure to remedy these phenomena, which would lead to an increase of the cost. Further, in the formation, the application of a pressure for compression to the metal sheet 9 or 9b, locating at the center in the thickness wise direction, causes extrusion of the grain layer 5 to the exposure pores 15. Hence, the density of the part of the grain layer 5 in the neighborhood of the exposure pores 15 is not likely to be high as compared to the part that abuts to the metal sheet 9, 9. Therefore, a difference of density is caused between the part on which the exposure pores 15 are formed and the part on which the exposure pores are not formed. This results in the difficulty to obtain a sufficient thickness of the chip 4.

[0033] Hence, the metal sheets 9 and 9b are given the alloy composition that contains Cu as the main material, which accounts for 95% or higher of the whole content, and any of Sn, Ni, P, Mn, and Fe or instead any of them plus an impurity element, which account(s) for 5% or lower of the whole content. The metal sheets 9 and 9b having such a composition have a rich elasticity and easily deform, and can therefore be prevented from being detached from the abrasive grain layers 5 and the joining layers 6 due to a spring back of the metal sheet 9 or 9b during shaping of the chip 4. Further, owing to metallic diffusion, the metal sheets 9 and 9b having such a composition can be firmly integrated with the bond of the chip 4 when they are sintered with the chip 4 that has been shaped. Furthermore, the metal sheets 9 and 9b can stop development of a crack, if it occurs. Still further, in a case where the chip 4 needs to be formed into a shape having a non-uniform cross sectional shape with hard abrasive grains 10 existing in the metal sheet 9 or 9b, the metal sheet 9 or 9b having such a composition can relatively easily deform to conform to the non-uniform cross sectional shape of the chip 4. [0034] The inclusion of metals such as Sn, etc. that have a lower melting point than that of Cu lowers the melting point and causes alloying at the bond boundary. As a result, the bond alloy configuration becomes inappropriate. This hinders occurrence of an optimum bond tail and lowers the cutting performance. Hence, it is desirable to use materials that have a melting point which is higher by 100 degrees C or more than the temperature at which the chip 4 is sintered. Further, even a Cu material causes a spring back if it has gotten a heavy work-hardening. Such a Cu material needs to be annealed to, desirably Vickers hardness of 40 to 90.

[0035] According to the embodiment described above, a chip 4 having a thickness that is smaller than conventional by 30% can be manufactured. And it was confirmed that the chip having this thickness can increase the cutting speed by 50 to 80%. [0036] As explained above, the metal sheets 9 and 9b according to the above embodiment integrally join the chip 4 including the abrasive grain layer 5 and the joining layer 6 to the base plate 2 and can stop development of a crack that might occur in the chip 4. Further, the metal sheets 9 and 9b, which are formed to have their exposure pores 15 and 15b cross every arbitrary circumferential line that runs along the circumference of the chip 4 about the center of the base plate 2, can have the abrasive grains 10 exist on the outer circumferential surface 22, which is the cutting edge, all the time through year-to-year uses for cutting works. Hence, the cutter 1 can sustain its cutting performance. [0037]

<Third Embodiment Metal meshes 19 (19a through 19d) according to a third embodiment that are applied in place of the metal sheets 9 and 9b will be explained with reference to Fig. 7. The metal meshes 19 are made of a netted metal material, and cover the surface of the chip 4 or exist right under the surface of the chip 4 or inside the chip 4. The net of the metal meshes 19 serves the same effect as that of the exposure pores 15 and 15b of the metal sheets 9 and 9b. The netted metal material is provided at substantially the center of the chip 4 in its thickness- wise direction, and has a size of 5 to 15 mesh per inch, with a wire diameter of 0.1 to 0.5 mm. [0038] Next, examples of the arrangement of the metal meshes 19 according to the present embodiment in the thickness- wise direction of the chip 4 will be explained with reference to Figs. 8A to 8D. The arrangement of the base plate 2, the joining layer 6, the abrasive grain layer 5, the abrasive grains 10, and the joint 7 is the same as the examples explained with reference to Fig. 2 to Fig. 7, and will not be explained repetitively. The point that makes the present embodiment different is the arrangement of the metal meshes 19a to 19d.

[0039] The metal mesh 19a shown in Fig. 8 A extends from the joining layer 6 to the end of the abrasive grain layer 5 in the radial direction of the cutter 1, and is arranged substantially all across the chip 4.

The metal mesh 19b shown in Fig. 8B does not extend to the end of the abrasive grain layer 5 in the radial direction unlike the metal mesh 19a shown in Fig. 8 A, and is arranged to about 1/2 to 2/3 of the abrasive grain layer 5 from the inner circumferential side. Even with this arrangement, the metal mesh 19b crosses the joint surface between the abrasive grain layer 5 and the joining layer 6 likewise the metal mesh 19a, and can serve to improve their joining strength. In Fig. 8B, the metal mesh 19b is not joined to the base plate 2, but can sufficiently serve the effect of reinforcing the abrasive grain layer 5 and the joining layer 6. [0040] The metal mesh 19c shown in Fig. 8 C is formed thin into a U-letter shape and arranged. The metal mesh 19c is provided near the center of the chip 4 in its thickness-wise direction.

Meanwhile, the metal mesh 19d shown in Fig. 8D is formed thick into a U-letter shape and arranged more peripherally in the thickness-wise direction of the chip 4. With this arrangement, the chip can have a significantly high rigidity and become suitable for cutting an especially hard work material 50. The third embodiment explained with reference to Figs. 8 has shown the examples of the metal meshes 19a to 19d, which may be applied in place of the metal sheets 9 and 9b. In Figs. 8C and 8D, the metal meshes 19c and 19d are U-letter shaped, but two or more metal meshes 19a or 19b shown in Fig. 8A or 8B may be arranged in the thickness- wise direction with a distance between them. [0041] Such arrangement of the metal mesh 19 can suppress scattering of debris of the chip 4 in case the chip 4 is broken by a shock during cutting. The use of the metal mesh 19 does not spoil the autogenous action of the abrasive grains 10 made of diamond, etc., i.e., the metal mesh 19 galls together with the abrasive grain layer 5 and does not contribute to reducing the cutting performance. The range across which the metal mesh 19 is arranged includes the joining layer 6 that contains no diamond or abrasive grains 10, which can improve the joining strength between the abrasive grain layer 5 and the joining layer 6 and can prevent a breakage of the abrasive grain layer 5 and the joining layer 6 at their boundary. Furthermore, the joining layer 6 contains the metal mesh 19 deep to its interface with the base plate 2 where they are welded, which means that the base plate 2 is also welded with the metal mesh 19 and a joining strength can be ensured between the chip 4 and the base plate 2. [0042] The metal mesh 19 explained above according to the third embodiment of the present invention can improve the strength of the chip 4 and the joining strength between the chip 4 and the base plate 2. This enables the chip 4 to be formed thin. As a result, fast and precise cutting can be realized and scattering of debris of the chip 4 can be suppressed if the chip 4 is broken. [0043] As explained above, the cutter 1 and the cutting machine 40 according to the embodiments described above include a reinforcing member in the joining layer and the abrasive grain layer, such that the reinforcing member extends across the layers in the radial direction, and can therefore have a firm joint between the base plate and the chip formed of the joining layer and the abrasive grain layer, and can stop development of a crack that might occur in the chip. Further, the cutter 1 according to the embodiments described above can use a thin chip, which reduces the cutting resistance to enable the cutter 1 to perform cutting at a high speed. [0044] The reinforcing member, which is made of a metal sheet having a plurality of exposure pores, does not influence the distribution of abrasive grains made of diamond, etc. in the abrasive grain layer, and can firmly join the joining layer with the abrasive grain layer, and the joining layer with the base plate. [0045] The exposure pores are arranged to cross without fail an arbitrary circumferential line that runs along the chip circumference about the center of the base plate. Therefore, the metal sheet can have the abrasive grains exist at any position thereof via the exposure pores. Hence, the cutting performance can be maintained over the entire thickness of the chip and stable cutting can be performed. [0046] The metal sheet is made of Cu, or an alloy whose main component is Cu, and has a thickness that is 15 to 30% of the thickness of the abrasive grain layer. Of the length of an arbitrary circumferential line that runs along the chip circumference about the center of the base plate, a percentage of 35 to 80% is line portions at which the arbitrary circumferential line is crossed by the exposure pores. Such a rate does not influence the distribution of the abrasive grains made of diamond, etc. in the abrasive grain layer or the cutting performance of the cutter, either.

[0047] The pores can have shapes of various types of circles or a squared shape, or any ones of these shapes in combination. Therefore, the reinforcing member can be easily manufactured by punching or the like. [0048] The reinforcing member may also be a netted metal material, with which a cutter with no less cutting performance can be realized, because the abrasive grains made of diamond, etc. do not lose the autogenous action because of the netted metal material since the netted metal material also galls together with the bond. [0049] The netted metal material has a size of 5 to 15 mesh per inch and a wire diameter of 0.1 to 0.5 mm. Therefore, the material can effectively suppress scattering of debris of the chip if the chip breaks due to a shock. [0050] Since the reinforcing member is joined to the base plate, a strong joint can be formed between the joining layer and the base plate and between the joining layer and the abrasive grain layer via the reinforcing member.

[0051] The base plate and the reinforcing member are joined by laser welding, which helps improve the joining strength between the chip and the base plate. [0052] Though the present invention has been explained based on its embodiments, the present invention is not limited to the embodiments described above, but can be modified in various manners within the scope of the spirit of the invention. For example, the embodiments have been explained with a segmented cutter, but the present invention can likewise be applied to a rim cutter that has a continuous cutting blade all along the outer circumference. The present invention can also likewise be applied to a cutter 30 shown in Fig. 9, which, unlike the configuration shown in Fig. 2, has a base plate 2a of another segmentation tape, having a slit 17 between the segments.

[0053] According to the embodiments described above, the chip 4 is joined to the base plate 2 by laser welding, but the joining manner is not limited to welding and other joining manners such as bonding may be employed.

[0054] This application claims priority to Japanese Patent Application No. 2008-066795 filed March 14, 2008, the disclosure of which is incorporated herein in its entirety.

Claims

Claim 1. A cutter, comprising: a base plate; and a cutting member that is fixed on a circumferential surface of the base plate, and cuts a work material by rotating together with the base plate, characterized in that the cutting member comprises: an abrasive grain layer that contains abrasive grains and hits the work material; a joining layer that joins the circumferential surface of the base plate to the abrasive grain layer; and a reinforcing member that is provided over an interior of the joining layer and an interior of the abrasive grain layer to reinforce binding inside the abrasive grain layer and binding inside the joining layer.

Claim 2. The cutter according to claim 1, characterized in that the reinforcing member has a plurality of exposure pores through which the abrasive grains contained in the abrasive grain layer are exposed.

Claim 3. The cutter according claims 2, characterized in that the plurality of exposure pores are arranged to cross an arbitrary circumferential line that runs along a circumference of the cutting member about a center of the base plate.

Claim 4. The cutter according to claim 3, characterized in that the reinforcing member is made of Cu or an alloy whose main component is Cu, and has a thickness that is 15 to 30% of a thickness of the abrasive grain layer, and a length of portions of the arbitrary circumferential line at which the arbitrary circumferential line is crossed by the exposure pores is 35 to 80% of a length of the arbitrary circumferential line.

Claim 5. The cutter according to claim 4, characterized in that the reinforcing member is made of an alloy that contains Cu that accounts for 95% or higher, any of Sn, Ni, P, Mn, and Fe that accounts for 5% or lower, and an impurity element that accounts for any rest.

Claim 6. The cutter according to claim 2, characterized in that the exposure pores have a circular shape, a squared shape, or both of a circular shape and a squared shape in combination.

Claim 7. The cutter according to claim 1, characterized in that the reinforcing member is made of a netted metal material.

Claim 8. The cutter according to claim 7, characterized in that the netted metal material has a size of 5 to 15 mesh per inch, and a wire diameter of 0.1 to 0.5 mm.

Claim 9. The cutter according to claim 1, characterized in that the reinforcing member is joined to the base plate.

Claim 10. The cutter according to claim 9, characterized in that the base plate and the reinforcing member are joined by laser welding.

Claim 11. A cutting machine, comprising: a body; a drive source; and a cutter including a base plate that is rotatably driven by the drive source, and a cutting member that is fixed on a circumferential surface of the base plate and cuts a work material, characterized in that the cutting member comprises: an abrasive grain layer that contains abrasive grains and hits the work material; a joining layer that joins the circumferential surface of the base plate to the abrasive grain layer; and a reinforcing member that is arranged over an interior of the joining layer and an interior of the abrasive grain layer to reinforce binding inside the abrasive grain layer and binding inside the joining layer.