JPH1199478A - Diamond cutting grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently supply and discharge cooling water to and from a cutting point and discharge chips from it by maintaining working uniformity from starting and finishing to use by making arrangement and an area of each of recessed parts optimum and forming a rake angle surface. SOLUTION: Bottom surfaces of a pair of recessed parts 14a, 14b formed on outer peripheral surface both end parts of a segment chip 13 on an outer periphery of a base plate 12 and a bottom surface of a recessed part 15 formed on the side of an adhering part are arranged on the roughly same circumference with the base plate 12 as its center, the sum of cross-sectional areas of a pair of the recessed parts 14a, 14b on the outer peripheral surface side is made to be within a range of 80-150% of a cross-sectional area of the recessed part 15 on the adhering part side, and a rake angle surface inclined in the rotating direction is formed on a surface positioned on a front surface in the grindstone rotating direction of the segment chip 13 and in the rear in the rotating direction of each of the recessed parts 14a, 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond cutting whetstone suitable for cutting stone, concrete, refractory and the like, and more particularly to a segment chip structure thereof.

[0002]

2. Description of the Related Art As a general diamond cutting whetstone, one in which a number of segment chips are fixed on the outer periphery of a disk-shaped iron substrate has been used. This so-called segment type is superior in the effect of discharging chips generated during cutting, compared to the continuous type in which an abrasive layer is fixed to the entire outer periphery of the substrate by the action of the slit provided between the segment chips. ing.

[0003] However, even with a segment type cutting wheel, it is difficult to completely discharge chips, and a large amount of frictional heat is likely to be generated particularly at an intermediate position of a segment chip. Cause.

As a solution to such a problem,
Japanese Utility Model Laid-Open Publication No. 61-35742 discloses a cutting wheel having a concave portion formed on the outer peripheral surface of a segment chip. In addition, the present applicant has proposed a diamond cutting whetstone obtained by further improving the cutting whetstone disclosed in the above official gazette,
No. 72560.

The cutting whetstone disclosed in Japanese Utility Model Laid-Open Publication No. Sho 62-172560 has a trapezoidal concave portion formed on both ends of an outer peripheral surface of a segment chip fixed to the outer periphery of a disk-shaped iron substrate. And a concave portion is formed at a substantially intermediate position of the bonding portion with the iron substrate. With such a structure, chips are easily discharged along the trapezoidal tapered surface of the trapezoidal concave portion, and by forming the concave portion at the intermediate position, the central portion of the segment chip, which is most likely to be hot at the time of cutting, is effectively made. It is possible to cool down.

[0006]

In processing a workpiece using a cutting grindstone, important characteristics required include:
There is efficient supply of cooling water and smooth discharge of chips. In this regard, in the cutting grindstone disclosed in Japanese Utility Model Application Laid-Open No. 62-172560, a larger amount of cooling water can be supplied as compared with a grindstone that does not form a concave portion, but the outer peripheral surface side due to wear due to use. When the pair of recesses becomes shallow, the cooling water supply efficiency decreases, and the chip discharge efficiency also decreases. Also, since the front side of the segment chip in the grindstone rotation direction is formed linearly in the normal direction of the substrate, the supplied cooling water is repelled on the front side of the substrate and the segment chip, and the cooling water is efficiently cut. There is a problem that it is difficult to be supplied to the market.

Further, as a characteristic required for the cutting wheel,
There is processing uniformity. Regarding the uniformity of this processing, in the cutting wheel disclosed in Japanese Utility Model Application Laid-Open No. 62-172560, the cross-sectional area of the concave portion on the bonding portion side is 1/1 / the sum of the cross-sectional areas of the pair of concave portions on the outer peripheral surface side. 2 or less, the pair of recesses on the outer peripheral surface side is lost due to wear due to use, and switching to the recessed portion on the adhesive portion side results in a reduction of the total cross-sectional area of the recessed portion to １ ／.
Therefore, the number of abrasive grains in contact with the workpiece increases, so that the cutting resistance increases and the sharpness decreases. As a result, there is a problem that after switching to the concave portion on the bonding portion side, a difference from the sharpness before that occurs, and uniformity of processing cannot be maintained.

In order to avoid this, the depth of each of the upper and lower concave portions is set to be at least half of the total height of the segment chip, and before the concave portion formed on the outer peripheral surface disappears, the depth of the adhesive portion side is reduced. It is also conceivable to make recesses appear and to keep the number of abrasive grains in contact with the workpiece as uniform as possible. However, it is not preferable that the depth of the concave portion is increased to increase the area where the upper and lower concave portions overlap, because the strength of the segment chip itself decreases.

The problem to be solved in the present invention is to provide a cutting whetstone in which a concave portion is formed at both ends of the outer peripheral surface of a segment chip and a concave portion is formed at a substantially intermediate position between the segment chip and an adhesive portion with a substrate. It is an object of the present invention to provide a segment chip structure that stably supplies cooling water efficiently from the beginning to the end of use, discharges chips smoothly, and maintains processing uniformity.

[0010]

According to the present invention, a pair of concave portions are formed at both ends of an outer peripheral surface of a segment chip fixed to the outer periphery of a disk-shaped substrate, and the pair of concave portions are located at substantially intermediate positions in the length direction of the segment chip. In a diamond cutting whetstone in which a second concave portion is formed at a bonding portion with the substrate, a rake angle inclined toward the rotational direction on a front surface of the segment chip in the rotational direction of the grindstone and a surface located rearward in the rotational direction of each concave portion. And a bottom surface of the pair of concave portions on the outer peripheral surface side and a bottom surface of the concave portion on the bonding portion side are disposed on substantially the same circumference around the substrate, and the pair of concave portions on the outer peripheral surface side are formed. Is set in a range of 80 to 150% of the cross-sectional area of the concave portion on the bonding portion side.

In the diamond cutting whetstone of the present invention, a rake angle surface inclined toward the rotation direction is formed on the front surface of the segment tip in the whetstone rotation direction and the surface of each recess located at the back in the rotation direction. The corners scoop up the cooling water and supply it forward with respect to the rotation direction, so that the cooling water can be efficiently supplied to the cutting point.
At the same time, the rake face efficiently scoops up the chips generated by the cutting, and efficiently discharges the chips to the outside by the cooling water.

The preferred rake angle is in the range of 3 to 20 degrees with respect to the normal direction of the substrate. If the angle of the rake angle is less than 3 degrees, the amount of cooling water to be scooped is small, and improvement in the supply efficiency to the cutting point cannot be expected. On the other hand, when the angle exceeds 20 degrees, the strength of the front end of the segment chip decreases.

Here, in order to prevent a decrease in the strength of the front end of the segment chip due to the formation of a rake angle, the concentration of abrasive grains at the front end is increased, or a binder having high wear resistance is used. Thus, the wear resistance can be enhanced.

Further, the diamond cutting whetstone of the present invention
Along with disposing the bottom surfaces of the pair of concave portions on the outer peripheral surface and the bottom surface of the concave portion on the bonding portion on substantially the same circumference centering on the substrate,
The sum of the cross-sectional areas of the pair of concave portions on the outer peripheral surface side is in the range of 80 to 150% of the cross-sectional area of the concave portion on the bonding portion side. This makes it possible to maintain the number of abrasive grains hitting the workpiece before and after the pair of concave portions on the outer peripheral surface disappears and the concave portion on the bonding portion side appears, at substantially the same level, from the beginning to the end of use. Processing uniformity can be maintained.

Further, the inclination of the surface located forward in the rotation direction of the pair of concave portions on the outer peripheral surface side may be greater than the inclination of the surface located rearward in the rotation direction, and the tip may be rounded. . By setting the shape of the concave portion in this way, the flow of the cooling water into the concave portion is increased, and the efficiency of supplying the cooling water to the cutting point can be further increased.

The depth of the pair of concave portions on the outer peripheral surface side and the depth of the concave portion on the bonding portion side are determined in accordance with the total height of the segment chip and the strength of the segment chip required from processing conditions. When the total height of the segment tip is 8 to 15 mm,
The depth of the recess is 45 to 55% of the total height of the segment chip.
Is desirably within the range. If the depth of both concave portions is less than 45% of the total height of the segment chip, there is a region where no concave portion is formed at the center in the height direction of the segment chip, and the sharpness is significantly reduced in this region.
On the other hand, if it exceeds 55%, the area where the two concave portions overlap is widened, and the strength of the segment chip is reduced.

[0017]

FIG. 1 is a front view of a cutting wheel showing an embodiment of the present invention, and FIG. 2 is a partially enlarged view of FIG.
In the cutting wheel 10 of the present embodiment, the segment chips 13 are fixed to the outer peripheral surface of the substrate 12 provided with the slits 11 at equal intervals, and a pair of concave portions 14a and 14b are formed at both ends of the outer peripheral surface of the segment chip 13. A second concave portion 15 is formed in a bonding portion with the substrate 12, and the segment chip 13 has a rake face inclined in the rotation direction on a front surface 16 in the rotation direction.

The dimensions of each part of the cutting wheel 10 are as follows: the outer diameter of the substrate 12 is 1005 mm;
3 number 60, same length 40mm, same height 15mm, same thickness 8.5m, groove width of recesses 14a and 14b 4.8mm, same depth 7.5mm, groove width of recess 15 8mm, same depth 7.5
mm.

The segment chip 13 is made of a diamond abrasive having a concentration of 20 and a binder of 100% cobalt.
In order to prevent a decrease in the strength of the front end portion due to the formation of the rake angle, the concentration of the abrasive grains at the front end portion is set to 25 to enhance the wear resistance.

The front face 16 in the rotation direction of the segment chip 13
The angle .theta. Between the normal direction of the substrate 12 and the rake face is set to 15 degrees. In the present embodiment, the rear surface 1 of the segment chip 13 in the rotation direction is used.
7 also has an inclined surface having the same angle as the front surface 16, and is further rounded at the tip.

Since the rake face is formed on the front surface 16 in the rotation direction, the scooped cooling water is reliably supplied to the cutting point without being repelled left and right. At the same time, chips generated by the cutting are efficiently scooped to the rake face, and the cooling water increases the efficiency of discharge to the outside. In addition, since the rear surface 17 in the rotation direction is also inclined and the tip is rounded, the flow of the cooling water is improved.

The pair of concave portions 14a and 14b on the outer peripheral surface side of the segment chip 13 have an outwardly expanding shape as shown in the drawing, so that when cutting, chips are discharged to the outside along the tapered surface. It is possible to reduce an increase in cutting resistance and abrasion of the segment chip 13 due to the remaining of the chip. Further, the supply of the cooling water can be efficiently performed by the concave portion 15 on the bonding portion side.

A pair of recesses 14a, 14 on the outer peripheral surface side
The inclination of the surface 18 located forward in the rotation direction of b is greater than the inclination of the surface 19 located rearward in the rotation direction, and the tip is rounded. Thereby, the flow of the cooling water into the concave portions 14a and 14b increases, and the efficiency of supplying the cooling water to the cutting point can be further increased. Furthermore, since the same rake angle as the rake angle formed on the rotation direction front surface 16 of the segment chip 13 is formed on the rotation surfaces rear surfaces 19 and 20 of the concave portions 14a, 14b, and 15 as well, the cooling water can be cut to the cutting point. Supply efficiency and chip discharge efficiency.

Furthermore, in the present embodiment, the sum of the cross-sectional areas of the pair of concave portions 14a and 14b on the outer peripheral surface side of the segment chip 13 is made substantially the same as the cross-sectional area of the concave portion 15 on the bonding portion side. The number of abrasive grains hitting the workpiece at the beginning of use, and the pair of recesses 14a, 14 on the outer peripheral surface side.
It is possible to maintain the number of abrasive grains hitting the workpiece after b disappears and the concave portion 15 on the bonding portion side appears at substantially the same level, thereby maintaining the uniformity of processing. Is obtained.

In the above embodiment, the side surface shape of the segment chip 13 is rectangular, but the side surface shape may be inverted trapezoidal to reduce the side resistance of the segment chip 13. In addition, the segment chip 13 may have a laminated structure in the thickness direction, and both outer portions may have higher wear resistance than other portions.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The diamond cutting whetstone according to the present invention shown in FIG.
Using a diamond cutting whetstone (comparative example) having the same shape as the whetstone described in No. 2-1725605, a comparative cutting test was performed under the following cutting conditions. Cutting conditions Cutting machine: Zambon SAE-3 Circumferential speed: 1650 m / min Cutting depth: 5.0 mm Feeding speed: 4000 mm Cooling water amount: 50 L / min Work material: Tenyama granite 1310 L × 800 W × 450
H

FIG. 3 shows the transition of the power consumption until the segment chips are worn down from 10 mm to 5 mm after the break-in and cutting are performed until the segment chips are worn by 5 mm in height. Since the power consumption during cutting is proportional to the cutting resistance, that is, the sharpness of the grindstone, the transition of the power consumption indicates a change in the sharpness of the grindstone.

As shown in FIG. 3, in the grindstone of the embodiment, the change in power consumption is small until the height of the segment chip wears from 10 mm to 5 mm, and the sharpness during this period is stable. Recognize. On the other hand, in the grindstone of the comparative example, the power consumption increases at the central portion in the height direction of the segment chip, and the power consumption increases particularly at the central portion, and the sharpness is reduced.

The life performance (= cutting area m ² / segment tip wear amount mm) of the grinding wheel until the height of the segment tip wears from 8 mm to 7 mm, that is, at the time of cutting the center portion, is as shown in FIG. The whetstone is 19.08m
² / mm, the grindstone of the comparative example was 15.21 m ² / mm, and it was confirmed that the life performance of the grindstone of the example was improved by about 25% as compared with the grindstone of the comparative example.

When the size of the swarf was measured, the size of the swarf when the grindstone of the example was used was about 1 on average.
It was 9.8 μm, and the size of the chips when the grindstone of the comparative example was used was about 16.4 μm on average. It can be seen that in the grindstone of the example, the rake angle formed on the front end face of the segment chip increases the bite into the workpiece.

Further, when a deviation from a predetermined cutting direction was measured to indicate the processing accuracy, the grindstone of the example was 0.52 mm, and the grindstone of the comparative example was 1.33 mm.
It was confirmed that the grindstones of the examples had better processing accuracy than the grindstones of the comparative examples.

[0032]

According to the present invention, the following effects can be obtained.

(1) A rake face inclined in the rotation direction to a face located in the rotation direction rear of each of the pair of recesses on the front and outer circumferential sides of the grinding wheel in the segment tip in the rotating direction and the recess on the bonding portion side. Is formed, the rake face scoops up the cooling water, supplies the cooling water forward in the rotation direction, and can efficiently supply the cooling water to the cutting point. At the same time, the rake face efficiently scoops up the chips generated by the cutting, and efficiently discharges the chips to the outside by the cooling water.

(2) The bottom surfaces of the pair of concave portions on the outer peripheral surface side and the bottom surface of the concave portion on the bonding portion side are arranged on substantially the same circumference centering on the substrate, and the pair of concave portions on the outer peripheral surface side are cut off. By setting the sum of the areas to be in the range of 80 to 150% of the cross-sectional area of the concave portion on the bonding portion side, the pair of concave portions on the outer peripheral surface side disappears and hit the workpiece before and after the concave portion on the bonding portion side appears. The number of abrasive grains can be maintained at substantially the same level, and uniformity of processing can be maintained from the beginning to the end of use.

(3) By making the inclination of the surface located forward in the rotation direction of the pair of recesses on the outer peripheral surface side larger than the inclination of the surface located rearward in the rotation direction, and making the tip end rounded In addition, the flow of the cooling water into the concave portion increases, and the efficiency of supplying the cooling water to the cutting point can be further increased.

[Brief description of the drawings]

FIG. 1 is a front view of a cutting whetstone showing one embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a graph showing transition of power consumption during cutting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cutting whetstone 11 Slit 12 Substrate 13 Segment chip 14a, 14b, 15 Concave part 16, 17 Segment chip surface 18, 19, 20 Concave surface

Claims (3)

[Claims] 1. A pair of concave portions are formed at both ends of an outer peripheral surface of a segment chip fixed to an outer periphery of a disc-shaped substrate, and a pair of concave portions are formed at substantially an intermediate position in a length direction of the segment chip and a bonding portion with the substrate is formed. In the diamond cutting wheel having the two concave portions, a rake angle surface inclined in the rotational direction is formed on the front surface of the segment chip in the rotational direction of the grindstone and the surface located in the rotational direction rear of each concave portion. The bottom surface of the pair of concave portions on the surface side and the bottom surface of the concave portion on the bonding portion side are arranged on substantially the same circumference around the substrate, and the sum of the cross-sectional areas of the pair of concave portions on the outer peripheral surface side is
A diamond cutting whetstone, wherein the cross-sectional area of the concave portion on the side of the bonding portion is in the range of 80 to 150%. 2. The diamond cutting wheel according to claim 1, wherein the rake angle is in a range of 3 to 20 degrees with respect to a normal direction of the substrate. 3. A pair of concave portions on the outer peripheral surface side, the inclination of a surface located forward in the rotation direction is larger than the inclination of a surface located rearward in the rotation direction, and a tip portion is rounded. The diamond cutting whetstone according to 1, 2.