JP3570646B2 - Grinding method of cam member - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cam member grinding method for reducing fluctuations in grinding load during machining and improving machining accuracy.
[0002]
[Prior art]
Conventionally, when grinding the outer peripheral surface of a cam member provided on a camshaft or the like, for example, a camshaft is connected to a rotary drive source to urge the rotary drive source, and a circular grindstone is formed on the outer peripheral surface of the rotating cam member. Is pressed while rotating to grind. In this case, if the camshaft is rotated at a constant angular velocity and ground, the outer peripheral shape of the cam member is not circular, so that the relative speed between the grindstone and the outer peripheral surface of the cam member differs depending on the position, and uneven grinding occurs due to load fluctuation. Therefore, conventionally, rotation control is performed so that the peripheral speed of the cam member is substantially constant, and load fluctuation is suppressed by reducing the speed.
[0003]
[Problems to be solved by the invention]
However, the above-described grinding method according to the related art has a problem that it takes a long time to manufacture and the production efficiency is low.
[0004]
Japanese Patent Application Laid-Open No. 4-171109 discloses that the rotational speed of a camshaft and the cutting amount of a cutter are synchronously controlled by an NC program, and the amount of grinding per unit time for each block obtained by dividing the camshaft is determined by the camshaft. A method of controlling the rotation speed so as to be substantially the same over the entire circumference is disclosed. However, this method has a drawback that control becomes complicated and it is extremely difficult to form an NC program.
[0005]
Furthermore, Japanese Patent Application Laid-Open No. 63-109970 discloses a cam grinding machine which automatically switches the rotational speed of a workpiece according to a processing stage and constantly controls the grinding amount to be substantially equalized. As described above, there is a problem that control is complicated.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can be easily controlled without increasing the cost of a grinding device, and can reduce the variation in grinding load to improve the processing accuracy. Another object of the present invention is to provide a cam member grinding method capable of improving production efficiency.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method of grinding an outer peripheral surface of a rotating cam member with a grinding tool,
The outer peripheral surface of the cam member is divided into a plurality of regions, and the grinding tool is used to grind the cam member per unit time in a region where the amount of grinding per unit rotation angle of the cam member by the grinding tool varies. In order to suppress the variation in the amount, the ratio of the maximum value to the minimum value of the rotation speed of the cam member in the region is set to the ratio of the maximum value to the minimum value of the grinding amount per unit rotation angle of the cam member in the region. The rotation speed of the cam member is controlled in accordance with a cosine characteristic while being set equal .
[0008]
According to the present invention, fast setting the rotational speed of the cam member relative to the region the grinding amount is small due to the grinding tool, for the realm grinding amount is not large, slowly rotating speed with increasing the amount of grinding Set the cosine characteristic to decrease.
[0010]
The ratio in this case, the ratio between the maximum value and the minimum value of the rotational speed of said cam member in a region where the grinding amount varies, the maximum value and the minimum value of the grinding amount per unit rotation angle of the cam member in the region It is preferable to set the value equal to the value, because it is possible to suppress the fluctuation of the grinding amount per unit time.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In FIG. 1, reference numeral 10 denotes a cam member to which the first embodiment is applied. The cam member 10 is configured to be rotatable around a point A, and is rotated in a direction indicated by an arrow B by a rotation driving source (not shown).
[0012]
The outer periphery of the cam member 10 is formed in a substantially elliptical shape protruding to one, from the point C ₀ to the point C ₁ to the arc centered on the point A, from the point C ₁ to the point C ₂ is formed in a straight line You. Then, from the point C ₂ to point C ₄ through the point C ₃ is formed in a predetermined curved, from point C ₄ to point C ₅ is formed again linearly, wherein from the point C ₅ to the point C ₀ arc the same diameter from the point C ₀ to the point C _1, is formed in concentric arcs. Point C ₃ forms a farthest apex from the point A. The cam angles of the points C _{0 to} C ₅ with respect to the straight line AC ₀ are α _{C0 to} α _C5 , respectively. In addition,
α _C0 = 0 [rad]
α _C3 = π [rad]
In the figure, the correspondence between the cam angles α _{C0 to} α _C5 is described on straight lines AC ₀ to AC ₅ .
[0013]
A circular grindstone 12 having a center point E as a center is provided in contact with the outer periphery of the cam member 10, and the grindstone 12 rotates at a constant rotational speed in the direction of arrow D. As shown in FIG. 2, the grinding stone 12 is controlled by an NC control device (not shown) so that the cutting amount t from the outer periphery of the cam member 10 is always constant.
[0014]
Here, the cam member 10 rotates, and as shown in FIG. 3, an arbitrary point C ₆ except for the point C ₃ on the line C ₁ C ₅ on the outer periphery of the cam member 10 comes into contact with the grindstone 12. The point C ₆ is not on the straight line connecting the center point A of the cam member 10 and the center point E of the grindstone 12. Thus, the cam angle alpha _C6 of the point _{C 6} for linear AC _0, is different from the angle of the straight line AE, i.e. a rotation angle theta _C6 of the cam member 10 relative to the straight line AC _0. The cutting control of the cam member 10 is performed by the NC control device according to the rotation angle θ _C6 .
[0015]
Next, the grinding amount at an arbitrary rotation angle θ of the cam member 10 will be described with reference to FIG.
[0016]
In Figure 2, the cam member 10, when the grinding wheel 12 shown by a solid line is ground by a predetermined rotation angle theta _1, it is in contact with the arc gh the whetstone 12 and the cam member 10. When the cam member 10 is rotated by the unit angle θ ₀ from the rotation angle θ ₁ , the grinding stone 12 and the cam member 10 are in contact with each other by an arc g′h ′ as shown by a dotted line in FIG. . Therefore, portions 14 surrounded by the circular arc gh and the arc G'h 'indicates a range to be ground by the grinding wheel 12 when the cam member 10 is rotated by a unit angle theta ₀ from the predetermined rotational angle theta _1. Therefore, the area of the site 14 corresponds to the grinding amount per unit angle theta ₀ of the cam member 10 at a predetermined rotation angle theta _1.
[0017]
FIG. 4A shows a graph of the grinding amount i (θ) per unit angle with respect to the rotation angle θ. When the grinding stone 12 is grinding a predetermined portion between the straight lines C ₁ C ₂ and the straight lines C ₄ C _{5 on} the outer periphery of the cam member 10, between the point J ₁ between the straight lines C ₁ C ₂ and the straight line C ₄ C ₅ grinding amount i (theta) takes a maximum value _{i J1, i J2} at point _{J 2.} Further, when the grinding stone 12 grinds near the boundary between the arc C ₀ C ₁ and the straight line C ₁ C ₂ and near the boundary between the straight line C ₄ C ₅ and the arc C ₅ C ₀ , the grinding amount i (θ) slightly increases. To increase.
[0018]
Therefore, the rotation angle θ point _{C 0} ~ point _{C 1} of the cam member 10, the points _{C 1} ~ point _{J 1,} point _{J 1} ~ point _{C 3,} point _{C 3} ~ point _{J 2,} point _{J 2} ~ point _{C 5} , divided into six regions 16 a to 16 f of the point _{C 5} ~ point _{C 0,} setting the rotational speed of the cam member 10 with respect to each region 16 a to 16 f.
[0019]
First, as shown in FIG. 4B, the rotation speed f _a (θ) of the cam member 10 when the grindstone 12 is grinding the region 16a is:
f _a (θ) = 1
And It should be noted that the rotation speed 1 is a normalized speed, and in an actual system, this is set to be a constant multiple. Here, the grinding amount k per unit time (corresponding to the area surrounded by each of the arcs gh and g′h ′ in FIG. 2) is substantially equal to the grinding amount per unit angle and the rotation speed of the cam member 10. It can be expressed as a product. For this reason, as shown in FIG. 4C, the grinding amount k (θ) per unit time in the region 16a is obtained by dividing the grinding amount i (θ) per unit angle at this time by i (θ) = i _0.
Then
k (θ) = f _a (θ) × i (θ) = i ₀
It becomes.
[0020]
The rotation speed f _b (θ) of the cam member 10 when the grindstone 12 is grinding the region 16b is represented by the following equation.
[0021]
f _b (θ) = (1/2 i _J1 ) [i _J1 + i ₀ + (i _J1 −i ₀ ) × cos {(θ−θ _C1 ) (π / (θ _J1 −θ _C1 ))}]
According to this equation, as shown in FIG. 4B, the instant at which the rotation angle θ of the grindstone 12 with respect to the cam member 10 changes from the region 16a to the region 16b, that is, the rotation speed f _b (θ _C1 ) when θ = θ _C1. Changes continuously from the rotation speed f _a (θ) = 1 in the region 16a, and the rotation speed f _b (θ) decreases along the cosine curve as the rotation angle θ advances. That is, when the rotation angle θ = θ _C1 , the maximum value of the rotation speed f _b (θ) in the region 16b is:
f _b (θ) = 1
It is. Then, at the moment from the area 16b to the area 16c, that is, when θ = θ _J1 , the rotation of the cam member 10 becomes the slowest. The rotation speed f _b (θ _J1 ) at this time is
f _b (θ _J1 ) = i ₀ / i _J1
This value is the minimum value of the rotation speed f _b (θ) in the region 16b. The ratio between the maximum value and the minimum value of the rotation speed f _b (θ) in this region 16b is
f _b (θ _J1 ) / f _b (θ _C1 ) = i ₀ / i _J1
This value is equal to the ratio i ₀ / i _J1 of the maximum value i _J1 and the minimum value i ₀ of the grinding amount i (θ) in this area 16b. The grinding amount k (θ _J1 ) per unit time at the rotation angle θ _{J1 at} this time is:
k (θ _J1 ) = f _b (θ _J1 ) × i _J1 = i ₀
Next, matching the grinding amount _{i 0} per unit time in the region 16a.
[0022]
Similarly, in the region 16C～16e, rotational speed _{f c} (θ) with respect to the rotation angle theta of the cam member _{10, f d (θ),} f e (θ) is expressed by the following equation.
[0023]
_{f c (θ) = (1} / 2i J1) [i J1 + i 0 - (i J1 -i 0) × cos {(θ-θ J1) (π / (θ C3 -θ J1))}]
f _d (θ) = (1 / 2i _J2 ) [i _J2 + i ₀ + (i _J2 −i ₀ ) × cos {(θ−θ _C3 ) (π / (θ _J2 −θ _C3 ))}]
f _e (θ) = (1 / 2i _J2 ) [i _J2 + i ₀ − (i _J2 −i ₀ ) × cos {(θ−θ _J2 ) (π / (θ _C5 −θ _J2 ))}]
The rotational speed _{f f (θ)} of the cam member 10 in the area 16f, like the rotational speed _{f a} in the region 16a (theta),
f _f (θ) = 1
It is. In each equation, as is clear from FIG. 4B, the rotation speed continuously changes at the boundaries between the regions 16a to 16f. In the regions 16d and 16e, the rotation speeds f _d (θ _J2 ) and f _e (θ _J2 ) at the rotation angle θ _{J2 at} which the grinding amount i (θ) per unit angle is the maximum are the rotations in the regions 16d and 16e. speed _{f d} (theta), becomes the minimum value of _{f e (θ),} the ratio of the maximum and minimum values of each of the regions 16d, 16e rotational speed _{f d} of the _{(θ), f e (θ} ) has a region 16a Similarly, it is equal to the ratio i ₀ / i _J2 of the maximum value i _J2 and the minimum value i ₀ of the grinding amount in each of the regions 16d and 16e. Therefore, the grinding amount k (θ _J2 ) per unit time at the rotation angle θ _J2 is:
k (θ _J2 ) = i _J2 × i ₀ / i _J2 = i ₀
As with the above-described grinding amount k (θ _J1 ) per unit time at the rotation angle θ _J1 , the grinding amount coincides with the grinding amount i ₀ per unit time in the region 16a.
[0024]
Therefore, the grinding amount k (θ) per unit time slightly increases near the boundary between the region 16a and the region 16b and near the boundary between the region 16e and the region 16f, as shown in FIG. 4C. In other cases, the grinding amount i ₀ is not exceeded, and it does not greatly change depending on the part to be ground, so that the load fluctuation of the grinding wheel 12 is suppressed, the rotation speed is stabilized, and a good ground surface is obtained. Can be. Further, since the rotation speed f (θ) is controlled to change according to the cosine curve, complicated processing such as feedback of the grinding amount or the like is unnecessary.
[0025]
Next, a method of grinding a cam member according to the second embodiment will be described.
[0026]
Hereinafter, portions different from the first embodiment will be described in detail, and in the drawings, the same components as those in the first embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted. .
[0027]
As shown in FIG. 5, the outer periphery of the cam member 10 used in the grinding method according to the second embodiment is located at a position displaced from each of the points C ₁ and C ₅ toward the point C ₀ by a predetermined angle m. Points L ₁ and L ₂ are set, and points C ₀ to L ₁ , points L ₁ to J ₁ , points J ₁ to J ₂ , points J ₂ to L ₂ , and points L ₂ to C ₀ It is divided into five regions 20a to 20e.
[0028]
Next, the rotation speed f (θ) of the cam member 10 according to the second embodiment will be described.
[0029]
As shown in FIG. 6B, the rotation speed of the cam member 10 when the grindstone 12 is grinding the region 20a,
f _a (θ) = 1
And The grinding amount k (θ) per unit time at this time is the same as in the first embodiment.
k (θ) = i ₀
It becomes.
[0030]
When the cam member 10 rotates and the grindstone 12 is grinding the area 20b, the rotation speed of the cam member 10 is expressed as follows.
[0031]
f _b (θ) = (1 / 2i _J1 ) [i _J1 + i ₀ + (i _J1 −i ₀ ) × cos {(θ−θ _L1 ) (π / (θ _J1 −θ _L1 ))}]
According to this formula, the rotation speed f (θ _L1 ) at the moment when the rotation angle θ of the grindstone 12 with respect to the cam member 10 changes from the region 20a to the region 20b, that is, when θ = θ _L1 , is equal to the rotation speed f in the region 16a. _The rotation speed f _b (θ) continuously changes from _a (θ) = 1, and the rotation speed f _b (θ) decreases according to the cosine curve as the rotation angle θ advances. Then, the moment applied from region 20b to region 20c, i.e., when theta = theta _J1, the rotation of the cam member 10 is slowest. The rotational speed f _b (θ _J1 ) at this time is f _b (θ _J1 ) = i ₀ / i _J1
It becomes. This value is the minimum value of the rotation speed f _b (θ) in the region 20b. The ratio between the maximum value and the minimum value of the rotation speed f _b (θ) in this region 20b is:
f _b (θ _J1 ) / f _b (θ _L1 ) = i ₀ / i _J1
This value is equal to the ratio i ₀ / i _J1 of the maximum value i _J1 and the minimum value i ₀ of the grinding amount i (θ) in this area 20b. The grinding amount k (θ _J1 ) per unit time at the rotation angle θ _{J1 at} this time is:
k (θ _J1 ) = f _b (θ _J1 ) × i _J1 = i ₀
Next, matching the grinding amount _{i 0} per unit time in the region 20a.
[0032]
In the region 20c, as shown in FIG.
f _C (θ) = i ₀ / i _J1
Has been maintained. The grinding amount i (θ _J2 ) per unit angle at the rotation angle θ _J2 is
i (θ _J2 ) = i _J2
Therefore, the grinding amount k (θ _J2 ) per unit time at this rotation angle θ _J2 is
k (θ _J2 ) = f _C (θ _J2 ) × i _J2 = i ₀ × i _J2 / i _J1
It is. As can be understood from FIG. 6A, since i _J2 is slightly smaller than i _J1 , the grinding amount k (θ _J2 ) also has a value slightly smaller than i ₀ .
[0033]
And in the area 20d,
f _d (θ) = (1 / 2i _J2 ) [i _J2 + i ₀ + (i _J2 −i ₀ ) × cos {(θ−θ _L2 ) (π / (θ _J2 −θ _L2 ))}]
The rotation speed f _d (θ) continuously changes from the region 20c according to the cosine curve, and the rotation speed f _d (θ _L2 ) at the rotation angle θ _L2 becomes 1.
[0034]
The rotation speed f _e (θ) in the region 20e is equal to the rotation speed f (θ) = 1 at the rotation angle θ _L2 .
And the grinding amount k (θ) per unit time is also
k (θ) = i ₀
It is.
[0035]
FIG. 6C shows a graph of the grinding amount k (θ) per unit time with respect to the rotation angle θ. As can be seen from this graph, the grinding amount k does not exceed i _0, and the grinding amount k per unit time does not greatly change. Further, the range in which the control according to the cosine curve is required is small, and the control of the rotation speed of the camshaft is further facilitated.
[0036]
In the above-described embodiment, the load variation is suppressed by replacing the rotation speed of the cam member at a portion where the grinding amount per unit angle greatly varies with a characteristic according to a cosine curve. In this case, the rotation speed may be changed smoothly in the vicinity of a portion where the grinding amount fluctuates greatly. Therefore, characteristics according to a sine curve or another curve may be applied.
[0037]
In addition, for example, each of the regions 16b to 16e in the first embodiment is further divided into two regions, and each region is controlled by a cosine curve. By adapting the characteristics of the curve, it is possible to perform a grinding process in which the load fluctuation of the grindstone is further suppressed.
[0038]
【The invention's effect】
According to the cam member grinding method of the present invention, the following effects and advantages can be obtained.
[0039]
Since the load fluctuation of the grindstone can be suppressed without performing complicated control, the cam member can be stably rotated and the processing accuracy can be improved. In addition, since the rotation speed is controlled to be reduced only in the portion where the load fluctuation increases, the overall manufacturing time can be shortened, and the production efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing a cam member and a grindstone used in a cam member grinding method according to a first embodiment of the present invention.
FIG. 2 is a partially enlarged plan view showing a cam member and a grindstone of FIG. 1;
FIG. 3 is a schematic plan view showing the cam member and the grindstone of FIG. 1 and in a state where the cam member has been rotated by a predetermined angle;
FIG. 4 is a graph illustrating a cam member grinding method according to the first embodiment;
FIG. 4A is a graph of a grinding amount per unit angle with respect to a rotation angle of a cam member;
FIG. 4B is a graph of the rotation speed with respect to the rotation angle of the cam member;
FIG. 4C is a graph of the grinding amount per unit time with respect to the rotation angle of the cam member.
FIG. 5 is a schematic plan view showing a cam member and a grindstone used in a cam member grinding method according to a second embodiment of the present invention.
FIG. 6 is a graph illustrating a method for grinding a cam member according to a second embodiment;
FIG. 6A is a graph of a grinding amount per unit angle with respect to a rotation angle of a cam member;
FIG. 6B is a graph of the rotation speed with respect to the rotation angle of the cam member;
FIG. 6C is a graph of the grinding amount per unit time with respect to the rotation angle of the cam member.
[Explanation of symbols]
10 Cam member 12 Grinding stones 16a-16f, 20a-20e Region θ Rotation angle f (θ) Rotation speed i (θ) Grinding amount per unit angle k (θ) Grinding amount per unit time

Claims (1)

In the method of grinding the outer peripheral surface of the rotating cam member with a grinding tool,
The outer peripheral surface of the cam member is divided into a plurality of regions, and the grinding tool is used to grind the cam member per unit time in a region where the amount of grinding per unit rotation angle of the cam member by the grinding tool varies. In order to suppress the variation in the amount, the ratio of the maximum value to the minimum value of the rotation speed of the cam member in the region is set to the ratio of the maximum value to the minimum value of the grinding amount per unit rotation angle of the cam member in the region. A method for grinding a cam member , wherein the setting is made equal and the rotational speed of the cam member is controlled in accordance with a cosine characteristic.

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