KR20170012027A - Cutting grindstone with boron compound added - Google Patents

Abstract

The present invention relates to a cutting process, which can inhibit the occurrence of a burr. According to a cutting grind stone (65) cutting a workpiece (W), cBN abrasive grains which are a boron compound and a ZrB_2 particle which is metal boride are added to diamond abrasive grains and fixed by a resin adhesive made of a phenolic resin and the like.

Description

{CUTTING GRINDSTONE WITH BORON COMPOUND ADDED}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting stone used for cutting a workpiece.

The boron compound has excellent solid lubricity. Therefore, by incorporating the boron compound into the cutting stone, it is possible to suppress the generation of frictional heat when the workpiece is cut by the cutting stone, and to suppress the consumption of the cutting stone. For example, even when the workpiece is a hard substrate such as sapphire, it has been found that good cutting results can be obtained by cutting using a cutting stone containing a boron compound such as cBN (cubic boron nitride) (see, for example, 1).

Japanese Laid-Open Patent Publication No. 2012-056012

However, even a cutting stone in which cBN, B ₄ C (boron carbide) or HBN (hexagonal boron nitride) is mixed as a lubricant, for example, can not ensure sufficient processing characteristics depending on the type of the workpiece. For example, when cutting a metal substrate or a metal-containing substrate with these cutting wheels, there is a case where a mold-releasing upper portion such as burrs is generated on the cutting surface of the substrate due to the malleability of the metal. Further, for example, when the content of cBN in the cutting stone is increased to improve the lubricity of the cutting stone, since the specific gravity of cBN (3.48 g / cm 3) is small, the cutting stone itself becomes lighter, The force of the enemy falls. Therefore, there is a problem that the cutting stone can not accurately and sufficiently transmit the cutting force to the machining point of the target cutting object, and the occurrence of burrs also increases.

Therefore, even when cutting a substrate containing a metal, for example, by using a cutting stone containing a boron compound for suppressing the generation of frictional heat, it is possible to suppress the generation of a mold releasing portion such as a burr, There is a problem in that the characteristics of the device being maintained well.

The present invention for solving the above-mentioned problems is a cutting grindstone in which a boron compound and a metal boride are added to diamond abrasive grains and fixed with a bond as a cutting grindstone for cutting a workpiece.

The diamond abrasive grains are preferably smaller in particle diameter than the boron compound.

Further, the boron compound is cBN, the metal boride is ZrB ₂ (zirconium boride), and the bond is preferably a resin bond. A metal bond may be used as the bond.

The cutting grindstone according to the present invention is characterized in that the boron compound and the metal boride are added to the diamond abrasive grains and fixed with a bond so that the occurrence of the release top of burrs and the like can be suppressed even when cutting a substrate containing a metal as a workpiece . In addition, it is possible to maintain good characteristics of a device manufactured by division.

Further, by making the grain size of the diamond abrasive grains contained in the cutting stone smaller than the grain size of the boron compound, the friction to the workpiece at the time of cutting can be reduced to suppress the generation of frictional heat, and the consumption of the cutting stone can be suppressed.

When the boron compound is cBN, the metal boride is ZrB ₂ , and the bond is a resin bond, for example, even when a substrate containing a metal is cut, generation of a release mold such as a burr is further suppressed , The consumption of the cutting stone is suppressed, and the damage to the workpiece is suppressed, whereby the characteristics of the divided devices can be well maintained.

1 is an exploded perspective view showing an example of a spindle unit having a cutting stone according to the first embodiment.
2 is a perspective view showing a part of the cutting apparatus.
3 is a cross-sectional view showing a state in which a workpiece is being cut with a cutting stone.
Fig. 4 is a table showing the lengths of burrs generated when the workpiece is cut with the cutting stone of Example 1, Comparative Example 1 or Comparative Example 2. Fig.

(Example 1)

The cutting stone 65 shown in Fig. 1 is, for example, a ring-shaped washer-shaped resin bond stone, in which cBN abrasive grains as a boron compound and ZrB ₂ grains as a metal boride are added to diamond abrasive grains, Resin bond.

A method of manufacturing the cutting stone 65 is, for example, as follows. First, a diamond abrasive having an average particle diameter of 40 占 퐉 and a cBN abrasive having an average particle diameter of 50 占 퐉 were mixed at a volume ratio of 10 to 20% with respect to a resin bond mainly composed of a phenol resin, an epoxy resin and a polyimide resin, 25 to 35% by volume of ZrB ₂ particles having an average particle diameter of 2 to 3 탆 are mixed and mixed by stirring. Subsequently, this mixture is pressed to form a predetermined thickness (150 占 퐉 thickness in this embodiment), and the external shape is also formed into a ring shape. Thereafter, sintering is performed at a sintering temperature of 180 ° C to 200 ° C for 7 to 8 hours to produce a cutting stone 65 having a mounting hole 650 shown in Fig. Also, as in this embodiment, it is preferable that the average grain size of diamond abrasive grains is made 10% or more smaller than the average grain size of cBN abrasive grains, because diamond abrasive grains act as auxiliary abrasive grains of cBN abrasive grains in cutting work. The volume ratio of the resin bond, diamond abrasive grains, cBN abrasive grains and ZrB ₂ grains can be appropriately changed depending on the types of abrasive grains and resin bonds. Here, the case where the average grain size of the cBN abrasive grains is 50 탆 is described, but the average grain size of the cBN abrasive grains used for cutting the metal is preferably 30 to 70 탆. More preferably, it is 40 to 60 mu m. On the other hand, the particle diameter of the diamond abrasive grains may be about 5 to 30% smaller than that of the cBN abrasive grains. More preferably, it is as small as about 10 to 20%. In addition, the number of times of diamond abrasion may be one or two smaller than the number of abrasive grains cBN. For example, if the cBN abrasive is # 240, select # 280 or # 320 for diamond abrasive.

The cutting stone 65 is not limited to an annular washer-shaped resin bond stone. For example, a base metal made of an aluminum alloy casting or the like and a cutting stone of a hub type integrally formed with the cutting edge may be used. In this case, for example, the cutting edge consists of a resin bond, diamond abrasive, cBN abrasive and ZrB ₂ particles.

As a bond for fixing the abrasive grains, not a resin bond but a metal bond may be used. For example, a manufacturing method of a metal bond stone having a ring shape of a washer shape is as follows. First, diamond abrasive grains having an average grain size of 40 占 퐉 and cBN abrasives having an average grain size of 50 占 퐉 are mixed in a volume ratio of 10 to 20%, respectively, with respect to a metal bond in which an alloy of copper and tin and a main ingredient of bronze are mixed with a small amount of cobalt and nickel, And ZrB ₂ particles having an average particle diameter of 2 to 3 탆 are mixed at a volume ratio of 25 to 35%. This mixture is kneaded and pressed to form a predetermined thickness, and the outer shape is also formed into a ring shape. Thereafter, sintering is performed at a sintering temperature of 600 ° C to 700 ° C for about 1 hour, whereby a ring-shaped washer-shaped metal bond stone can be produced.

A metal boride is, ZrB ₂ particle _{addition, CrB, CrB 2, Cr 3} B 2, TiB 2, ZrB 2, ZrB 3, NbB 2, TaB 2, may be a metal boride such as MoB, or WB. For example, when the metal boride in the cutting stone 65 is made of TiB ₂ , the cutting stone 65 is suitable for cutting the workpiece containing aluminum. When the metal boride in the cutting stone 65 is made of CrB or CrB ₂ , the cutting stone 65 is used for a longer period of time even at a high temperature in an oxygen atmosphere owing to oxidation resistance possessed by CrB and CrB ₂ Lt; / RTI > That is, even if the cutting speed is increased and the workpiece is cut at a high speed, and the supply amount of cutting water serving as the cooling liquid is reduced, even in a state where the contact portion between the cutting stone and the workpiece becomes high, deterioration of the cutting stone 65 And the cutting force can be maintained for a long period of time.

The spindle housing 60 provided in the spindle unit 6A shown in Fig. 1 rotatably receives the spindle 61. As shown in Fig. The axial direction of the spindle 61 is a direction orthogonal to the X-axis direction (Y-axis direction), and the tip end of the spindle 61 protrudes from the spindle housing 60 in the -Y direction. And a fixing flange 62 to which the cutting stone 65 is mounted is fixed to the projecting portion by a nut 63. [ The fixing flange 62 has a flange portion 620 extending outward in the radial direction (direction orthogonal to the axial direction of the spindle 61) and a flange portion 630 extending in the thickness direction (Y-axis direction) from the flange portion 620. [ And a boss portion 621 formed on the side surface thereof with a screw 621a.

An annular attaching / detaching flange 67 is mounted on the boss portion 621 in a state where the boss portion 621 is inserted into the mounting hole 650 of the cutting stone 65. The attaching / detaching flange 67 has an engaging hole 67a corresponding to the boss portion 621. When the attaching / detaching flange 67 is mounted on the boss portion 621, a ring-shaped fixing nut 68 screwed to the screw 621a is tightened to the screw 621a. The cutting stone 65 is pressed against the flange portion 620 by the attaching and detaching flange 67 so that the cutting stone 65 is sandwiched from both sides in the Y axis direction by the attaching and detaching flange 67 and the fixing flange 62, (61). Then, as the spindle 61 is rotationally driven by a motor (not shown), the cutting stone 65 also rotates at a high speed.

The cutting apparatus 1 shown in Fig. 2 is a device for cutting a workpiece W sucked and held by the holding table 3 by a cutting means 6. Fig.

The holding jig 30 shown in Fig. 2 is mounted on the jig base 32 of the cutting apparatus 1. As shown in Fig. The holding surface 30a of the holding jig 30 is provided with a plurality of relief grooves for avoiding contact between the holding jig 30 and the cutting stone 65 when the cutting stone 65 is inserted into the workpiece W 300 are formed. In the holding jig 30, a suction hole (not shown) for sucking the workpiece W is formed to penetrate in the thickness direction (Z-axis direction).

The jig base 32 on which the holding jig 30 is mounted is connected to a not shown suction source through a suction tube 32a and one end of the suction tube 32a is opened on the jig base 32. [ The holding jig 30 is mounted on the jig base 32 to constitute a holding table 3 for holding the workpiece W by suction. The holding table 3 is movable in the X-axis direction and rotatable.

Alignment means 12 for detecting a line to be divided S to be cut of the workpiece W is disposed above the movement path of the holding table 3. The alignment means 12 is provided with an image pickup means 120 for picking up an image of the upper surface Wa of the workpiece W. Based on the image obtained by the image pickup means 120, Can be detected. In the vicinity of the alignment means 12, a cutting means 6 for cutting the workpiece W held by the holding table 3 is formed. The cutting means 6 is formed integrally with the alignment means 12, and both move in the Y-axis direction and the Z-axis direction.

The cutting means 6 shown in Fig. 2 is provided with a spindle unit 6A having a cutting stone 65 and a cutting water supply nozzle 65 for supplying cutting water to a contact portion between the cutting stone 65 and the workpiece W. [ (69).

The workpiece W shown in Fig. 2 is, for example, a substrate having an outer shape of a quadrangular shape, and on the upper surface Wa of the workpiece W, there are three device areas Wc in the illustrated example. In the device region Wc, a plurality of devices D are formed in a lattice-like region partitioned by, for example, a line to be divided S shown in Fig. 3. In each device D, An electrode portion Wd (not shown in Fig. 2) containing a stainless steel material containing iron as a main component is formed. Then, as shown in Fig. 3, the electrode portion Wd also exists on the line to be divided S.

The operation of the cutting apparatus 1 when the workpiece W shown in Fig. 2 is cut by the cutting stone 65 and the operation of the cutting means 65 including the cutting stone 65 are described below with reference to Figs. 1 to 4, (6) will be described.

A holding jig 30 is mounted on a jig base 32 shown in Fig. The workpiece W is carried on the holding table 3 and the workpiece W is placed on the holding surface 30a of the holding jig 30. [ The suction force calculated by a suction source (not shown) connected to the jig base 32 is transmitted to the holding surface 30a, so that the workpiece W is attracted and held on the holding surface 30a.

The holding table 3 holding the workpiece W is conveyed in the -X direction and the upper surface Wa of the workpiece W is picked up by the image pickup means 120 Is detected. The cutting means 6 is driven in the Y axis direction and the position in the Y axis direction of the line S to be divided and the cutting stone 65 to be cut is determined .

After the position of the cutting stone 65 and the detected line to be divided S in the Y-axis direction is determined, the holding table 3 for holding the workpiece W is further fed out in the -X direction, (6) is fed and fed in the -Z direction. An unillustrated motor rotates the spindle 61 at a high speed and a cutting stone 65 fixed to the spindle 61 is inserted into the workpiece W while rotating at a high speed in accordance with the rotation of the spindle 61 , And the line to be divided S is cut. The cutting water supply nozzle 69 ejects the cutting water to the contact portion between the cutting stone 65 and the workpiece W when the cutting stone 65 is inserted into the workpiece W, And the cutting water is supplied to the grinding wheel 65.

When the workpiece W advances in the -X direction to a predetermined position in the X axis direction where the cutting stone 65 cuts the line S to be divided along the X direction, The cutting stone 65 is moved away from the workpiece W and the holding table 3 is moved in the + X direction to return to the original position. Then, the same cutting operation is sequentially performed while feeding the cutting stone 65 in the Y-axis direction at intervals of the adjacent division scheduled lines S, thereby cutting all the lines S to be divided in the same direction do. When the holding table 3 is rotated 90 degrees and then the same cutting is performed, all the lines S to be divided are all cut longitudinally and laterally.

3, for example, when the electrode portion Wd is present on the line to be divided S, the cutting stone 65 is inserted into the electrode portion Wd on the line to be divided S , When the cutting stone 65 reaches the relief grooves 300 of the holding jig 30, the line to be divided S is full-cut. At this time, a burr B extending from the electrode portion Wd to the relief groove 300 is generated due to the electrical property of the stainless steel material constituting the electrode portion Wd. Here, the allowable maximum value of the length of burrs B generated by cutting is generally less than 200 mu m, preferably not more than 150 mu m.

The length of the burr B generated when the cutting is performed using the cutting stone 65 of the first embodiment is such that the mean value of the length of the burr B is 90 占 퐉 as shown in the table T shown in Fig. , The maximum value of the length of the burr B was 125 mu m and the deviation of the burr B was 35 mu m. That is, the average value and the maximum value of the lengths of the burrs B were less than the allowable maximum value of the burr lengths of 200 mu m.

(Comparative Example 1)

In the comparative example 1, cutting grindstone 65a is used in place of cutting grindstone 65 in the first embodiment to cut the workpiece W in the same manner as in the case of using the cutting grindstone 65 of the first embodiment Respectively. The cutting stone 65a is a washer-shaped washer having an outer shape of an annular shape in which B ₄ C abrasives (average particle size of 15 탆) as a boron compound are added to diamond abrasive grains having an average grain size of 45 탆 and fixed with a resin bond B1 made of phenol resin or the like As a resin bonded stone, the thickness is 150 μm.

The length of the burr Ba produced when the cutting is performed using the cutting stone 65a of the comparative example 1 has an average length of the burr Ba of 140 mu m as shown in the table T in Fig. , The maximum value of the length of the burr Ba was 275 mu m and the deviation of the length of the burr Ba was 135 mu m. That is, the maximum value of the length of the burr Ba exceeded the allowable maximum value of the burr length of 200 mu m.

(Comparative Example 2)

In the comparative example 2, a cutting stone 65b is used in place of the cutting stone 65 in the first embodiment, and a cutting operation is performed on the workpiece W in the same manner as in the case of using the cutting stone 65 of the first embodiment Respectively. Cutting the grinding wheel (65b) has a mean particle diameter of 35 ㎛ in which diamond abrasive grains ZrB ₂ particles as a metal boride in the addition of (average particle size 2 ~ 3 ㎛) and secure it with the resin bond B1 made of a phenol resin and the like, outer dimensions of the annular A washer-shaped resin bond stone having a thickness of 150 μm.

The length of the burr Bb generated when the cutting is performed using the cutting stone 65b of the second comparative example is such that the average value of the lengths of the burrs Bb is 105 mu m as shown in the table (T) , The maximum value of the length of the burr Bb was 230 mu m and the deviation of the burr Bb was 125 mu m. That is, the maximum value of the length of the burr Bb exceeded the allowable maximum value of the burr length of 200 mu m.

The maximum value of the length of the burr Ba generated when the workpiece W was cut by the cutting stone 65a of Comparative Example 1 exceeded the allowable maximum value. On the other hand, both of the average value and the maximum value of the length of the burr B generated when the workpiece W was cut by the cutting stone 65 of Example 1 were all less than the allowable maximum value. This result is because, unlike the cutting wheel (65a), and containing ZrB ₂ particles, the cutting wheel 65. That is, the weight of the cutting stone 65 itself becomes heavy due to the ZrB ₂ grain, which is a heavy metal boride having a specific gravity of about 6.1 g / cm 3, so that the cutting stone 65 in the case of rotating the cutting stone 65 at a high speed, (Swinging in the Y-axis direction) in the Y-axis direction is thought to be reduced. Since the cutting motion of the cutting stone 65 is reduced and the cutting stone 65 is inserted perpendicularly into the electrode portion Wd when the cutting stone 65 is inserted into the workpiece W, It is considered that the cutting stone 65 hardly contacts the portion other than the target machining point of the workpiece W and the contact between the divided electrode portion Wd and the cutting stone 65 is also reduced. Therefore, it is considered that the length of the burr B that has been generated can be set to be less than the allowable maximum value. Further, it is considered that the characteristics of the device D manufactured by division can be maintained satisfactorily.

Further, by the average particle diameter (45 ㎛) of the diamond abrasive grains in the grinding wheel compared to the large cutting than the average particle size (15 ㎛) of the boron compound is B ₄ C grinding wheel (65a), the cutting wheel 65, the diamond abrasive grains in the grinding wheel The average particle size is 40 占 퐉, which is smaller than the mean particle diameter of the cBN abrasive grains, which is a boron compound in the grindstone, by 50% or more by 10% or more. Therefore, when the cutting stone 65 is inserted into the workpiece W, the cBN abrasive having a larger average diameter comes into contact with the workpiece W prior to the abrasive grains. Therefore, the workpiece W and the cutting stone 65 are less likely to occur. As a result, frictional heat generated at the contact portion between the workpiece W and the cutting stone 65 is reduced and consumption of the cutting stone 65 is reduced, so that it is considered that the cutting stone 65 can be used for a longer period of time.

The maximum value of the length of the burr Bb generated when the workpiece W was cut by the cutting stone 65b of the comparative example 2 exceeded the allowable maximum value of the burr length. On the other hand, the average value and the maximum value of the length of the burr B generated when the workpiece W was cut by the cutting stone 65 of Example 1 were all less than the allowable maximum value of the burr length. This is because, unlike the cutting stone 65b, the cutting stone 65 contains cBN abrasive grains. That is, the solid lubricating property of the cBN abrasive suppresses the generation of frictional heat between the electrode portion Wd and the cutting stone 65 when the cutting stone 65 is inserted into the workpiece W, It is considered that the length of the burr B that has been generated can be set to be less than the allowable maximum value because baking or the like as a cause is suppressed. Further, it is considered that the characteristics of the device D manufactured by division can be maintained satisfactorily.

In comparison with the cutting stone 65b which does not contain a boron compound as a lubricant in the grinding stone, the cutting stone 65 contains cBN abrasive grains as a boron compound and the average grain size of diamond abrasive grains in the abrasive grains is 40 mu m, Is smaller than the mean grain size of the cBN abrasive grains (boron compound) of 50% by 10% or more. Therefore, it is considered that the generation of frictional heat occurring at the contact portion between the workpiece W and the cutting stone 65 is suppressed by the solid lubricity of the cBN abrasive grains. The cBN abrasive grains having an average grain size larger than the abrasive grains 65 come into contact with the workpiece W prior to diamond abrasion so that the workpiece W and the cutting grindstone 65 The friction generated at the contact portion of the contact portion is less. As a result, the frictional heat generated at the contact portion between the workpiece W and the cutting stone 65 is reduced, so that the consumption of the cutting stone 65 is reduced and the cutting stone 65 can be used for a longer period of time.

65: The cutting stone of Example 1
650: mounting ball
6A: Spindle unit
60: Spindle housing
61: spindle
62: Fixed flange
620: flange portion
621: boss part
621a: Screw
63: Nut
67: Removable flange
67a: engaging ball
68: Fixing nut
1: Cutting device
12: alignment means
120:
6: Cutting means
69: Cutting water supply nozzle
3: retention table
30: Holding jig
30a: a holding surface of the holding jig (holding surface of the holding table)
300: relief home
32: Jig base
32a: suction pipe
W: Workpiece
Wa: the upper surface of the workpiece
Wc: device area
Wd: electrode portion
S: Line to be divided
D: Device
B: Burr
65a: cutting stone of Comparative Example 1
65b: cutting stone of Comparative Example 2

Claims (3)

As a cutting stone for cutting a workpiece,
A cutting grindstone in which a boron compound and a metal boride are added to diamond abrasive grains and fixed with a bond. The method according to claim 1,
Wherein the diamond abrasive grains have a particle diameter smaller than that of the boron compound. 3. The method according to claim 1 or 2,
The boron compound is a cBN, wherein the metal boride is ZrB _2, the bond is a resin bond, a cutting grinding wheel.

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