JP3568438B2 - Centerless grinding blade - Google Patents

Description

【００１９】
【表１】

【００２０】
表１からわかるように、寿命の点だけからみると比較品のブレードの寿命が最も長い。しかし、比較品のブレードは硬質砥粒層全体の砥粒集中度を高くしたもので、被加工物の入口側の偏摩耗により、他の部位はまだ使用可能であるにもかかわらず寿命となったものである。また頂面の偏摩耗が加工精度にも影響している。発明品１のブレードは、被加工物の入口側の硬質砥粒層の砥粒集中度は比較品のブレードと同じであるのでブレードの寿命もほぼ同程度であり、他の部位の砥粒集中度は低くなっているので頂面の偏摩耗がなく、これにより被加工物の振動が少なくなり、良好な加工精度が得られた。また、入口側以外では砥粒集中度を低くしているので、比較品に比べて砥粒使用量が少なく、より低いコストで同等の寿命が達成できた。発明品２も発明品１と同様に偏摩耗がないので、良好な加工精度が得られたが、各チップの継ぎ目部分における砥粒層硬度の違いから継ぎ目部分に微小な段差が生じて被加工物と干渉し、これにより継ぎ目部分に欠けが生じてブレードの寿命が若干短くなった。従来品は頂面が超硬合金製であるので、ダイヤモンド砥粒を用いた硬質砥粒層で頂面を形成した発明品１，２および比較品に比してブレードの寿命は短い。
【００２１】
【発明の効果】
本発明によって以下の効果を奏することができる。
【００２２】
（１）センタレスブレードのブレード頂面をダイヤモンド砥粒またはＣＢＮ砥粒のいずれかまたは両方を含む硬質砥粒層で形成し、この硬質砥粒層内の砥粒の含有率を、ブレード頂面の被加工物の出口側よりも入口側を大きくすることにより、被加工物の入口側の偏摩耗を防止することができる。
【００２３】
（２）砥粒含有率が異なる複数のチップをブレード頂面の長手方向に順次配設することにより、製造上の困難さを伴うことなく、硬質砥粒層の砥粒含有率を段階的に変化させることができる。
【００２４】
（３）砥粒含有率が異なるチップどうしの継ぎ目線がブレード頂面の長手方向に対して３０〜７０度傾斜するように配設することにより、チップの継ぎ目において砥粒含有率が急変するのを抑制することができる。
【図面の簡単な説明】
【図１】本発明の実施形態を示すブレードの斜視図である。
【図２】図１のブレードの正面図である。
【図３】センタレス研削加工を示す説明図である。
【符号の説明】
１ 本体
２ 硬質砥粒層
２ａ〜２ｈ チップ
１０ ブレード
２０ 研削砥石
２１ 調整車
２２ ブレード
２２ａ 頂面
Ｔ 継ぎ目線
θ 夾角（傾斜角）
Ｗ 被加工物[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a centerless grinding blade used for centerless grinding of a round or cylindrical workpiece.
[0002]
[Prior art]
There is centerless grinding as a grinding process suitable for outer circumference grinding of small diameter round bars and pipes. In the centerless grinding, as shown in FIG. 3, a grinding wheel 20 for grinding the workpiece W, and an adjusting wheel 21 which is opposed to the grinding wheel 20 in a state of holding the workpiece W and applies a braking force to the workpiece W. And a centerless grinder provided with a blade 22 installed between the grinding wheel 20 and the adjusting wheel 21 to support the workpiece W, and the grinding wheel 20 and the adjusting wheel 21 are The workpiece W is 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.
[0003]
In this centerless grinding, since the adjusting wheel 21 is arranged with its axis inclined with respect to the grinding wheel 20, the workpiece W slides on the top surface 22a of the blade 22 in the direction of arrow A. I do. 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, and various attempts have been made to prevent such a scratch from being generated. .
[0004]
The top surface of the blade is required to have wear resistance to the workpiece, abrasive grains falling off the grinding wheel, or cutting chips, etc., so the material of the blade may be cast iron, hard steel, hard metal such as cemented carbide, etc. In many cases, a material is used, and a material whose top surface is formed of an abrasive layer using diamond abrasive grains or CBN abrasive grains, various ceramics, or the like is also used.
[0005]
For example, Japanese Patent Application Laid-Open No. 54-137796 discloses that a metal bond segment whetstone in which a grindstone layer in which diamond or CBN abrasive grains are fixed by a metal bond and a metal layer containing no abrasive grains are integrally fixed on a steel base. A bonded blade is described. It is said that this blade significantly improves wear resistance and durability.
[0006]
[Problems to be solved by the invention]
Incidentally, the wear of the blade top surface in the actual centerless grinding is not uniform over the entire top surface, and the degree of wear varies depending on the portion. In particular, when viewed in the longitudinal direction of the blade top surface, the degree of wear is greater at the entrance side of the workpiece than at the exit side. Therefore, if the wear on the inlet side reaches the life limit, the life will end even if other parts can be used. If uneven wear occurs on the top surface of the blade, the workpiece vibrates during grinding, causing poor machining accuracy and uneven wear of the grinding wheel. When uneven wear of the grinding wheel occurs, the life of the grinding wheel is shortened, and the working efficiency is reduced, such as an increase in the number of dressings. Therefore, it is very important to prevent uneven wear of the blade top surface.
[0007]
The problem to be solved by the present invention is to reduce top surface wear, particularly uneven wear, in centerless grinding while suppressing an increase in blade manufacturing cost.
[0008]
[Means for Solving the Problems]
The centerless grinding blade of the present invention is a blade that supports a workpiece located between a grinding wheel and an adjustment wheel in centerless grinding, and has one or both of diamond abrasive grains or CBN abrasive grains on the blade top surface. The hard abrasive layer includes a hard abrasive layer, and the content of the abrasive grains in the hard abrasive layer is larger on the blade top surface on the inlet side than on the outlet side of the workpiece.
[0009]
As described above, the wear of the blade top surface is larger at the inlet side of the workpiece than at the outlet side, so that the abrasive content on the inlet side is made larger than that at the outlet side to prevent uneven wear on the inlet side. Can be. In this case, the rate of increase of the abrasive content from the outlet side to the inlet side may be changed stepwise, or may be changed linearly or curvedly. The material of the blade body is not particularly limited, and iron, cemented carbide, or a combination thereof can be used.
[0010]
When the abrasive content of the hard abrasive layer is changed stepwise, a plurality of chips having different abrasive content can be sequentially arranged in the longitudinal direction of the blade top surface to form the hard abrasive layer. In this case, in order to suppress an abrupt change in the abrasive content at the seam of the chips, it is preferable that the seam lines of the adjacent chips are arranged so as to be inclined by 30 to 70 degrees with respect to the longitudinal direction of the blade top surface. desirable.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a perspective view of a blade showing an embodiment of the present invention, and FIG. 2 is a plan view showing a tip arrangement of a hard abrasive layer on the top surface of the blade.
[0012]
The blade 10 according to the present embodiment has a hard abrasive layer 2 formed at the tip of a main body 1 and serves as a top surface. The main body 1 is made of steel (JIS G4051 S45C), and has a length of 320 mm and a thickness of 10 mm. The hard abrasive layer 2 has a width of 6 mm, and eight chips 2a to 2h whose upper surfaces are inclined in the thickness direction of the main body 1 are arranged in the longitudinal direction of the blade. The shape of each of the chips 2a to 2h is determined so as to be inclined by 60 degrees with respect to the longitudinal direction of the top surface, and the abrasive content is increased in the order of the chips 2h to 2a.
[0013]
Specifically, each of the chips 2a to 2h is a hard abrasive layer made of a diamond abrasive and a metal component as a binder, and the planar shapes of the chips 2b to 2g are parallelograms having an included angle (inclination angle) θ of 60 degrees. Each of the chips 2a and 2h has a trapezoidal shape having a hypotenuse of 60 degrees.
[0014]
The content of diamond abrasive grains for each chip is as follows: chips 2a and 2b have abrasive concentration of 200, chips 2c and 2d have abrasive concentration of 180, chips 2e and 2f have abrasive concentration of 160, and chips 2g and 2h have abrasive concentration. The grain concentration is 140. By changing the degree of concentration of abrasive grains in the longitudinal direction of the blade top surface in this way, the abrasion resistance of the inlet side when the workpiece advances in the direction of arrow A in FIG. In addition, uneven wear on the inlet side is prevented.
[0015]
By preventing uneven wear of the blade top surface, vibration of the workpiece during grinding is reduced and machining accuracy is improved, and uneven wear of the grinding wheel is suppressed, grinding wheel life is improved, and the number of dressings And the work efficiency is improved. Also, by reducing the concentration of abrasive grains at other portions of the blade top surface on the workpiece inlet side, it is possible to reduce the amount of expensive diamond abrasive grains used.
[0016]
The above embodiment shows an example of the blade of the present invention, the present invention is not limited to the above embodiment, the overall shape of the blade, the shape of the tip of the hard abrasive layer, the number and the like Can be changed as appropriate.
[0017]
(Test example)
The blade (invention product 1) of the embodiment of the present invention shown in FIG. 1 (invention product 1) has the same shape and material as the invention product 1 (invention product 2) except that the seam line of each chip of the hard abrasive layer is not inclined. ), A blade (comparative product) in which the overall shape is the same as that of the invention 2 and the abrasive content of each chip of the hard abrasive layer is constant (comparative product) A round bar grinding test was performed using a blade (conventional product) having a surface formed. The grinding conditions are shown below, and the test results are shown in Table 1.
[0018]

[0019]
[Table 1]

[0020]
As can be seen from Table 1, the life of the comparative blade is the longest in terms of life alone. However, the blade of the comparison product has a high concentration of abrasive grains in the entire hard abrasive layer, and due to uneven wear on the inlet side of the workpiece, the life of other parts is still available even though it is still usable It is a thing. The uneven wear on the top surface also affects the processing accuracy. The blade of the invention product 1 has the same degree of concentration of the abrasive grains in the hard abrasive layer on the inlet side of the workpiece as the blade of the comparative product, so that the life of the blade is almost the same, and the concentration of the abrasive grains in other parts is Since the degree was low, there was no uneven wear of the top surface, thereby reducing the vibration of the workpiece and obtaining good machining accuracy. In addition, since the concentration of the abrasive grains was low except at the entrance side, the amount of abrasive used was smaller than that of the comparative product, and the same life could be achieved at lower cost. Inventive product 2 did not have uneven wear similarly to inventive product 1, so that good machining accuracy was obtained. However, due to differences in the hardness of the abrasive layer at the seam portion of each chip, a minute step was generated at the seam portion, and the workpiece was processed. Interference, which resulted in chipping at the seam, which slightly shortened the life of the blade. Since the top surface of the conventional product is made of a cemented carbide, the life of the blade is shorter than that of the invention products 1 and 2 and the comparison product whose top surfaces are formed by a hard abrasive layer using diamond abrasive grains.
[0021]
【The invention's effect】
The following effects can be obtained by the present invention.
[0022]
(1) The top surface of the centerless blade is formed of a hard abrasive layer containing either or both of diamond abrasive grains and CBN abrasive grains, and the content of the abrasive grains in the hard abrasive layer is determined based on the top surface of the blade. By making the inlet side larger than the outlet side of the workpiece, uneven wear on the inlet side of the workpiece can be prevented.
[0023]
(2) By sequentially arranging a plurality of chips having different abrasive grain contents in the longitudinal direction of the blade top surface, the abrasive grain content of the hard abrasive layer can be increased step by step without difficulty in manufacturing. Can be changed.
[0024]
(3) By arranging the seam line between chips having different abrasive grain contents at an angle of 30 to 70 degrees with respect to the longitudinal direction of the blade top surface, the abrasive grain content at the seam of the chips suddenly changes. Can be suppressed.
[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]
Reference Signs List 1 main body 2 hard abrasive layer 2a to 2h tip 10 blade 20 grinding wheel 21 adjusting wheel 22 blade 22a top surface T seam line θ included angle (tilt angle)
W Workpiece

Claims (2)

A blade supporting a workpiece between a grinding wheel and an adjustment wheel in centerless grinding, wherein the top surface of the blade is formed of a hard abrasive layer containing one or both of diamond abrasive grains and CBN abrasive grains, A plurality of chips having different abrasive content are sequentially arranged in the longitudinal direction of the blade top surface, and the abrasive content of the hard abrasive layer is changed in a stepwise manner. A centerless grinding blade whose ratio is larger on the inlet side than on the outlet side of the workpiece on the blade top surface. 2. The centerless grinding blade according to claim 1, wherein a seam line between adjacent chips is disposed so as to be inclined by 30 to 70 degrees with respect to the longitudinal direction of the blade top surface.

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