JP3466976B2 - Method for crowning a sliding member and apparatus used for the method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crowning method for forming a sliding surface of a sliding member such as a tappet used in an engine valve device into a smoothly curved convex surface, and an apparatus used therefor. is there.

[0002]

2. Description of the Related Art For example, a sliding surface of a tappet, which is in contact with a cam in a four-cycle engine, is crowned so that a central portion thereof has a curved convex surface higher than an outer peripheral portion thereof. There is. If such a convex surface is formed, the tappet rotates around its axis along with the rotational driving of the cam during operation, so uneven wear of the sliding surface of the tappet can be prevented. Conventionally, a lathe, a flat grindstone, or a linear grindstone is used to perform the crowning process. However, such a conventional method requires skill to form a smooth convex surface.

Therefore, an object of the present invention is to provide a crowning method capable of forming a smooth convex surface without requiring skill and an apparatus used therefor. In addition, as an example showing a related technique
There is No. 03.

[0004]

In order to achieve the above object, the crowning method according to claim 1 is such that the one end face which is the front face of the rotating abrasive material has its rotation axis centered on the other end face.
A sliding member is attached to the polishing surface consisting of a conical surface with an apex on top .
While rotating about the axis, the axis is pressed in a posture orthogonal to the conical surface to form a sliding surface.

A crowning apparatus according to claim 2 is
An abrasive having a conical surface whose one end face as the front surface has a vertex near the other end face , and an abrasive that rotates around the axis of the polishing surface, and a sliding member on the polishing surface A rotary pressing machine that presses in a posture in which the axis is orthogonal to the conical surface while rotating around to form a sliding surface.

During the crowning process, the sliding surface of the sliding member is such that the one end surface serving as the front surface of the abrasive is closer to the other end surface.
It is pressed against a polishing surface consisting of a conical surface having an apex at a position orthogonal to this. As a result, the outer peripheral portion of the sliding surface that contacts the conical surface that is the polishing surface is ground by the rotating conical surface. At this time, since the sliding member rotates, the sliding surface in contact with the conical surface is a curved conical surface,
It has a smooth convex shape and is ground to be axisymmetric.

[0007]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view of a crowning device according to the present invention. This apparatus comprises a grinder 2 provided with an abrasive material 1, and a tappet (sliding member) 3 that is pressed against a polishing surface 11 of the abrasive material 1 while rotating the same, and a convex sliding surface 3 having a curved top surface.
1 is provided with a rotary pressing machine 4.

The grinding machine 2 is supported by a base member 21 to which the abrasive material 1 is fixed by a baking means, a chuck 23 for holding a rotary shaft 22 projecting therefrom, and a bearing 26 extending from the chuck 23. A motor 25 for rotating the chuck shaft 24 is provided. Further, the abrasive 1 is formed in a cylindrical shape having an opening 10 in the center, and one end face 1a which is the front face thereof is concentric with the axis C1 of the abrasive 1 and the other end face 1b of the abrasive 1 is formed. A polishing surface 11 formed of a conical surface having an apex P is formed near the edge. When the polishing surface 11 is thus a conical surface, the generatrix 11a is a straight line, so that the polishing surface 11 can be easily dressed using a diamond cutting tool or the like.

The rotary pressing machine 4 holds a chuck 41 that holds the tappet 3, a motor 43 that rotates a chuck shaft 42 extending from the chuck 41, and moves the whole of them to the polishing surface 11 side in parallel with the chuck shaft 42. The feeding means 44 such as a ball screw is provided. The rotary pressing machine 4 is disposed so as to be inclined in a direction orthogonal to the polishing surface 11, and when the tappet 3 is pressed against the polishing surface 11 by moving the whole, the tappet 3 has its axis C2 as the polishing surface. It is pressed in a direction orthogonal to 11. The width W of the polishing surface 11 is set larger than the diameter φd of the sliding surface 31 of the tappet 3. The tappet 3 is rotated in the same direction R2 as the rotation direction R1 of the abrasive 1 shown in the schematic front view of FIG.
Alternatively, it may be rotated in any direction of the reverse direction R3.

Next, a procedure for crowning the tappet 3 with the above apparatus will be described. First,
While the abrasive 25 is rotated by the motor 25 of the grinder 2 shown in FIG. 1 and the tappet 3 is rotated by the motor 43 of the rotary press 4, the entire rotary press 4 is moved to the abrasive 1 side by the feeding means 44. To move. In this way, the sliding surface 31 of the top of the tappet is pressed against the conical polishing surface 11 of the polishing material 1 in a posture orthogonal to this surface. The top surface, which is the sliding surface 31 of the tappet 3, is a flat surface that is not curved because it is not ground. Therefore, the left and right outer peripheral parts a and b of the sliding surface 31 orthogonal to the axis C2 of the tappet 3 shown in FIG.
, As shown in FIG. 3, comes into contact with the conical surface of the polishing surface 11,
The outer peripheral parts a and b are ground by the rotating polishing surface 11. At this time, since the tappet 3 is rotated by the rotary pressing machine 4, the outer peripheral portions a and b of the sliding surface 31 that comes into contact with the polishing surface 11 formed of the conical surface are uniformly ground over the entire circumference.

In this way, by continuing the grinding work while pressing the sliding surface 31 of the tappet 3 against the polishing surface 11, the sliding surface 31 is sequentially ground from the outer peripheral portion to the center side, and finally, As shown in FIG. 4, a smoothly curved convex sliding surface 31 having a high central portion and a low outer peripheral portion is formed. The sliding surface 31 has an axially symmetrical shape around the axis C2.

During such a grinding operation, since the abrasive 1 is usually made of carbon steel, sparks are generated due to the frictional resistance between the abrasive surface 11 and the sliding surface 31. After the tappet 3 has been fed by a predetermined amount and the sliding surface 31 has been accurately ground, the frictional resistance becomes small and the generation of sparks stops, so that this is confirmed and the grinding operation ends. As described above, since the tappet 3 is merely pressed against the polishing surface 11 of the polishing material 1 in the direction orthogonal to the polishing surface 11, the smooth sliding surface 31 can be easily ground without requiring skill.

At this time, for example, as shown in FIG. 1, when the diameter φD of the position where the sliding surface 31 of the abrasive 1 intersects the axis C2 is 400 mm and the diameter φd of the sliding surface 31 is 26 mm, this sliding The amount of crowning formed on the moving surface 31 (difference in height between the center and the peripheral edge shown in FIG. 4) e is 5 × 10 ⁻³ m
m (5 μm), that is, the crowning ratio = 5 × 10 ⁻³ /
In order to form the sliding surface 31 having 26 curved surfaces, the inclination angle θ of the generatrix 11a of the polishing surface 11 of the polishing material 1 with respect to the surface orthogonal to the axis C1 may be set to about 1 °.

Although the tappet has been described in the above embodiments, the present invention is also applicable to the crowning process of sliding members such as valve lifters and rocker arms having a curved convex top surface. .

[0015]

As described above, according to the present invention, a smooth convex surface can be formed on the sliding surface of the sliding member without requiring skill.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a crowning device according to an embodiment of the present invention.

FIG. 2 is a schematic front view showing the device.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2, showing a state at the initial stage of polishing work.

FIG. 4 is a cross-sectional view corresponding to FIG. 3, showing a finished state of a polishing operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Abrasive material, 2 ... Grinding machine, 11 ... Polishing surface, 3 ... Sliding member (tapet), 31 ... Sliding surface, 4 ... Rotary pressing machine, C1 ...
Polishing surface axis, C2 ... Sliding member axis

Claims (2)

(57) [Claims] 1. A method for forming a sliding surface of a sliding member into a smoothly curved convex surface, wherein one end face which is a front face of a rotating abrasive material is closer to the other end face.
A sliding surface is formed by pressing the sliding member around a conical surface having an apex on the axis of rotation while rotating the sliding member around the axis while the axis is perpendicular to the conical surface. A method for crowning a sliding member. 2. A device for forming a sliding surface of a sliding member into a smoothly curved convex surface, wherein a polishing surface is formed by a conical surface whose one end face serving as a front face has an apex toward the other end face. And a polishing material that rotates about the axis of the polishing surface, and slides the sliding member on the polishing surface while pressing it around the axis while pressing the axis in a posture orthogonal to the conical surface. A crowning device having a rotary pressing machine for forming a surface.