JP2000263395A - Centerless grinding blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit a raising of a production cost of a blade and reduce an abrasion of a top surface and to prevent a generation of a flaw of a subject to be processed by making a longitudinal direction center portion of a blade top surface a straight line state parallel to a moving direction to be processed and making both ends a taper shape or a curved shape from a center portion to both ends. SOLUTION: In a blade 10, a top surface 2 is formed at a tip end of a body 1 and in a shape viewed in a longitudinal direction of a top surface 2, a longitudinal direction center portion is made a straight line state parallel to a moving direction of a subject to be processed and both end portions are made a taper shape descending from a center portion to both ends. The body is made of a steel. A top surface 2 is formed by joining ten diamond sintered chips 3 and three ultra hard alloy blocks 4 at both end portions on an upper surface of the body inclined to a thickness direction of the body 1. Thereby, an impact of a collision is relaxed when an end surface of a subject to be processed enters/retreats to a blade top surface, and an abrasion of a blade top surface is reduced. A bad influence to a subject to be processed is disappeared by reducing an abrasion of a blade top surface and a generation of a flaw is prevented and a high accurate grinding processing can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centerless grinding blade used for centerless grinding a round or cylindrical workpiece.

[0002]

2. Description of the Related Art There is a centerless grinding as a grinding process suitable for the outer circumference grinding of a small diameter round bar or a pipe. In this centerless grinding, as shown in FIG. 3, a grinding wheel 20 for grinding the workpiece W, and an adjustment wheel 2 which faces the grinding wheel 20 in a state of holding the workpiece W and applies a braking force to the workpiece W.
1 and a centerless grinding machine provided with a blade 22 for supporting the workpiece W, which is provided between the grinding wheel 20 and the adjusting wheel 21. As shown by arrows in the figure, the grinding wheel 20 and the adjusting wheel 21 Are rotated in the same direction, the workpiece W is rotated in the opposite direction, and the outer periphery of the workpiece W is ground by the grinding wheel 20.

In this centerless grinding, the adjusting wheel 21
The workpiece W is placed on the top surface 22 a of the blade 22 because the
It moves in the direction of arrow A while sliding on the top. At this time, a spiral wound may be generated on the workpiece W due to a scratch generated on the top surface 22a of the blade 22 due to wear or the like. In order to prevent such a scratch, the top surface 22a of the blade 22 may be formed. Various attempts have been made to improve the shape and material of the device.

For example, Japanese Utility Model Application Laid-Open No. 58-106139 and Japanese Utility Model Application Laid-Open No. 58-177263 disclose blades having a hard wooden top surface. According to this blade, the top surface of the blade is made of a material softer than the workpiece, so that the workpiece is not damaged by a feed mark or the like, and the top surface is easily re-ground, so that re-grinding is possible. It is said that a good top surface can always be maintained.

Further, Japanese Utility Model Laid-Open No. 63-64454 discloses a blade in which a material having greater toughness than ceramics is fixed to the entrance portion of the top surface and ceramics is subsequently fixed to make the top surface the same surface. ing. According to this blade, it is described that no damage occurs at the entrance portion, no damage is caused on the workpiece, and the wear resistance of the ceramic can be sufficiently exhibited.

In Japanese Utility Model Laid-Open No. 2-66941,
There is disclosed a blade having a curved top surface as viewed in an inclined direction. According to this blade, even in the case of grinding a workpiece having a rectangular parallelepiped shape on the outer periphery, such as a round bar material compression-molded with a mold, the workpiece does not chip, cracks, and other defects do not occur, and the blade is smooth. It is said that it is possible to grind.

Further, Japanese Utility Model Laid-Open No. 7-20251 discloses a blade provided with a fluid ejection port for supplying a fluid toward a workpiece on a top surface. According to this blade, the blade and the workpiece can be sufficiently lubricated, so that the material of the blade can be made hard, and a reduction in grinding accuracy due to wear of the blade can be prevented.

[0008]

However, the blades described in the above publications have the following problems, respectively. JP-A-58-106139,
The blade described in Japanese Utility Model Laid-Open Publication No. 58-177263 is
Since the top surface of the blade is made of wood, the material cost is low and the top surface can be easily re-ground, but a long life cannot be expected. Further, the blade described in Japanese Utility Model Application Laid-Open No. 63-64454 has a material having higher toughness than ceramics and is further fixed with ceramics so as to be on the same surface. Causes a step, which causes damage to the workpiece.

The blade described in Japanese Utility Model Application Laid-Open No. 2-66941 is effective for a workpiece having a projection on the outer periphery, but is not suitable for a workpiece such as an ordinary round bar. In this case, the stability of the workpiece is deteriorated. In addition, actual opening 7
The blade described in Japanese Patent No. -20251 increases the manufacturing cost of the blade.

[0010] By the way, the top surface of the blade is required to have abrasion resistance to the workpiece, abrasive grains falling off the grinding wheel, or cutting chips, etc. Therefore, the material of the blade may be cast iron, hard steel, super steel, or the like. Hard materials such as hard alloys are often used, and in recent years, diamond sintered bodies, C
A BN (cubic boron nitride) sintered body, a silicon carbide nitride sintered body, and the like are also used.

Further, the top surface of the blade has been subjected to special processing such as forming the surface shape according to the workpiece and making the surface flatness and surface roughness high precision. Costs considerable costs. Therefore, in order to reduce the manufacturing cost of the blade, expensive materials such as a diamond sintered body, a CBN sintered body, and a silicon carbide sintered body are used only at the top of the blade and further only at a part of the top, and other materials are used. Some measures have been taken such as using low-cost materials such as cemented carbide.

The problem to be solved by the present invention is to reduce the abrasion of the top surface and suppress the generation of scratches on the workpiece in the centerless grinding while suppressing the increase in the manufacturing cost of the blade.

[0013]

The centerless grinding blade of the present invention is a blade for supporting a workpiece between a grinding wheel and an adjustment wheel in centerless grinding,
The shape as viewed in the longitudinal direction of the top surface of the blade tip is characterized in that the central portion in the longitudinal direction has a linear shape parallel to the moving direction of the workpiece, and has a tapered shape or a curved shape descending from the central portion to both ends. .

The central portion of the blade top surface in the longitudinal direction is formed in a straight line parallel to the moving direction of the workpiece, and both ends on the inlet side and the outlet side of the workpiece are formed in a tapered or curved shape. The impact of the collision when the end of the workpiece enters and exits the blade top surface is reduced, and the wear on the blade top surface is reduced. By reducing the abrasion of the blade top surface, adverse effects on the workpiece are eliminated, scratches are prevented, and high-precision grinding is obtained.

Here, when both ends of the blade top surface are tapered, it is desirable that the taper angle of the tapered portion be 2 degrees or less. When the taper angle is larger than 2 degrees, the stability when the workpiece moves while sliding on the top surface of the blade deteriorates, and the workpiece easily dances up and down. Therefore, the taper angle is 2 degrees or less. More preferably, 0.3 to 1
The range of degrees.

When both ends of the blade top surface are curved, the radius of curvature of the curved portion is desirably 800 mm or more. When the radius of curvature is smaller than 800 mm, the stability when the workpiece moves while sliding on the top surface of the blade becomes poor, and the workpiece easily dances up and down. Therefore, the radius of curvature is preferably 800 mm or more, more preferably. Is in the range of 1000 to 8000 mm. Here, at the boundary between the straight portion at the center and the curved portion at the end, the tangential direction of the curved portion is set to be the same as the straight portion, so that the workpiece is not damaged at the boundary and smoothly. So that it can slide.

As the material for forming the top surface of the blade, the same material as that of a conventional blade can be used. However, materials having excellent wear resistance include diamond sintered bodies, CBN sintered bodies, and silicon carbide sintered bodies. , Or a cemented carbide is used alone or in combination. In particular, when a cemented carbide is used in combination with any one of a diamond sintered body, a CBN sintered body, and a silicon carbide sintered body, at least the central portion in the longitudinal direction of the blade top surface is a diamond sintered body, CBN
It is desirable to form either a sintered body or a silicon carbide sintered body, and to form the other end portions with a cemented carbide. In this case, the seam between the diamond sintered body, the CBN sintered body, and the silicon carbide sintered body and the cemented carbide is located at the tapered portion or the curved portion, thereby causing a difference in wear resistance. It is possible to prevent the occurrence of a step at the joint.

[0018]

FIG. 1 is a perspective view of a blade showing an embodiment of the present invention, and FIG. 2 is a front view. The blade 10 according to the present embodiment has a top surface 2 formed at the tip of a main body 1.
c is a linear shape parallel to the moving direction of the workpiece (indicated by an arrow A in the figure), and both end portions Ta and Tb are tapered so as to descend from the central portion Tc to both ends.

The main body 1 is made of steel (JIS G4051 S45).
C), 400 mm long and 6 mm thick at the top.
The top surface 2 is located on the upper surface of the main body 1 inclined in the thickness direction of the main body 1.
It is formed by bonding three diamond sintered chips 3 and three cemented carbide blocks 4 at both ends. Here, in this embodiment, both ends Ta and Tb of the top surface 2, that is, portions on the inlet side and the outlet side of the workpiece at the time of grinding are tapered so as to descend toward both ends.

In this embodiment, the taper angle θ of the tapered portion is 0.7 degrees. By providing such a taper at both ends Ta and Tb, the impact of collision when the end of the workpiece enters and exits the top surface 2 of the blade 10 during grinding is reduced, and the wear of the top surface 2 is reduced. Is done. If the taper angle is 2 degrees or less, there is no effect on the stability when the workpiece moves while sliding on the top surface 2, and the wear of the top surface 2 is reduced by reducing the wear on the top surface 2. Is prevented, and high-precision grinding is obtained.

The material forming the top surface 2 is a combination of a diamond sintered body and a cemented carbide in consideration of cost.
The diamond sintered body is composed of ten diamond sintered bodies over the entire length (230 mm) of the central portion Tc in the longitudinal direction of the top surface 2 and a part (10 mm in length) near the center of both ends Ta and Tb. The tip 3 is formed by bonding to the upper surface of the main body 1 and the cemented carbide is entirely formed at both ends Ta and Tb (each having a length of 7 mm).
5 mm) are formed by bonding three cemented carbide tips 4 to the upper surface of the main body 1. In particular, since the seam between the diamond sintered body and the cemented carbide is located at the tapered portion, the occurrence of a step at the seam due to the difference in wear resistance is prevented.

[Test Example] The blade of the present invention shown in FIG. 1 (Invention 1), a blade having the same dimensions and shape as the invention 1 and using a CBN sintered body instead of a diamond sintered body (Invention 2) The blade of Invention 1 having a curved portion with a radius of curvature of 2000 mm (Invention 3), the taper of Invention 2 having a curved portion with a radius of curvature of 2000 mm (Invention 4), and the taper of Invention 1 Blade with a taper angle of 2.5 degrees (comparative product 1), blade with a curvature radius of the curved portion of invention product 3 of 500 mm (comparative product 2), and blade without a tapered portion on the top surface (comparative product 2) A grinding test of a round bar was performed using the conventional products 1 and 2). Table 1 shows the main specifications of the blades subjected to the test, and Table 2 shows the test results.

[0023]

[Table 1]

Grinding condition Workpiece: Material JIS G4401 SK-5 Dimension before grinding 15.0 mmφ × 60 mm Length Dimension after grinding 14.7 mmφ Rotational peripheral speed: Grinding wheel 1800 m / min Adjustment wheel 28 m / min Number of processing: grinding machine 9600 bottles / day / unit Test period: 2 years

[0025]

[Table 2]

As shown in Table 2, in the case of the blade using the diamond sintered body, the blades of the inventions 1 and 3 having the proper taper or curve formed at both ends of the blade top surface continuously have 24 to Processing was possible for 25 weeks, and the operation rate of the grinding machine was high. The invention product 1, the blade (comparative product 2) in which the taper angle of the tapered portion is larger than the appropriate value and the blade (comparative product 2) in which the radius of curvature of the curved portion is smaller than the appropriate value.
Scratches occurred earlier than in No. 3, the number of blade corrections increased, the replacement cycle became shorter, and the operating rate of the grinding machine decreased. A blade without a tapered or curved portion (conventional product 1) is scratched even earlier, requiring eight corrections including replacement of cemented carbide tips, further reducing the operating rate of the grinding machine, Costs have also risen. In the case of a blade using a CBN sintered body, the same applies between the inventions 2 and 4 having the appropriate taper or curve formed at both ends of the blade top surface and the conventional product 2 having no taper or curve. The result was obtained.

[0027]

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

(1) The central portion in the longitudinal direction of the blade top surface should be a straight line parallel to the moving direction of the workpiece, and both ends on the inlet side and the outlet side of the workpiece should be tapered or curved. Accordingly, the impact of the collision when the end of the workpiece enters and exits the blade top surface is reduced, and the wear on the blade top surface is reduced. By reducing the abrasion of the blade top surface, adverse effects on the workpiece are eliminated, scratches are prevented, and high-precision grinding is obtained.

(2) At least the central portion in the longitudinal direction of the blade top surface is formed of any one of a diamond sintered body, a CBN sintered body, and a silicon carbide sintered body, and the rest is formed of a cemented carbide, thereby increasing the cost. In addition to reducing the use of various materials, the seam between the diamond sintered body, the CBN sintered body, and the silicon carbide sintered body and the cemented carbide is located at the tapered portion or the curved portion, so that the difference in wear resistance is improved. Can prevent the occurrence of a step at the seam due to the above.

[Brief description of the drawings]

FIG. 1 is a perspective view of a blade showing an embodiment of the present invention.

FIG. 2 is a front view of the blade of FIG. 1;

FIG. 3 is an explanatory view showing a centerless grinding process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Top surface 3 Sintered diamond chip 4 Cemented carbide chip 10 Blade 20 Grinding wheel 21 Adjustment wheel 22 Blade 22a Top surface θ Taper angle

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teiji Hirashima 210 Noritake Diamond, Tanushimaru-cho, Ukiha-gun, Fukuoka Prefecture Inside Noritake Diamond Co., Ltd. F term (for reference) 3C043 AA08 CC03 DD05

Claims (5)

[Claims] 1. A blade for supporting a workpiece between a grinding wheel and an adjustment wheel in centerless grinding,
A centerless grinding blade in which the shape of the blade top surface in the longitudinal direction is a tapered shape or a curved shape in which the central portion in the longitudinal direction has a linear shape parallel to the moving direction of the workpiece and descends from the central portion to both ends. 2. The centerless grinding blade according to claim 1, wherein the tapered angle of the tapered portion of the blade top surface is 2 degrees or less. 3. The centerless grinding blade according to claim 1, wherein a radius of curvature of the curved portion of the blade top surface is 800 mm or more. 4. The blade according to claim 1, wherein at least a central portion in the longitudinal direction of the blade top surface is formed of any one of a diamond sintered body, a CBN sintered body, and a silicon carbide sintered body, and the remainder is formed of a cemented carbide. 3. The blade for centerless grinding according to any one of 3. 5. The centerless grinding blade according to claim 4, wherein a joint between any one of the diamond sintered body, the CBN sintered body, and the silicon carbide sintered body and the cemented carbide is located at the tapered portion or the curved portion. .