JPS59126167A - Cylinder quenched by laser - Google Patents

Abstract

PURPOSE:To aim at reducing the cost of quenching a piston due to a short- time process of the piston, by quenching and hardening only predetermined range parts of the piston on the thrust side and the counter-thrust side thereof. CONSTITUTION:Abrasion in the inner peripheral surface of a cylinder liner is concentratedly occurred on the thrust side and the counter-thrust side in the vicinity of the top dead center of the top ring part. Therefore, laser is irradiated to an area over an angular range of thetaA angle on the thrust side, but an area over an angular range of thetaB on the counter-thrust side, and both area quenched to be hardened. The quenching range on the thrust side is preferably to extend over thetaA=90 through 120 deg. On the other hand the quenching range on the counter-thrust side is preferable to extend over thetaB=90 to 10 deg. since the abrassion on the counter-thrust side is larger than that on the thrust side. Further, the length LS which is a quenching ranged in the sliding direction of the piston is set to LS=0.1 through 0.5L, and the depth of the quenched and hardened sections is made more than the allowable abrassion limit. With this arrangement, the time for the irradiation of laser may be made short, and the quenching may be made at a low cost while sufficient wear-resistant capability is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder whose inner peripheral surface is hardened by laser irradiation.

BACKGROUND ART Cylinders or cylinders in which the inner peripheral surface of a cylinder liner (sleeve) is hardened to improve wear resistance are already known. Laser hardening, which causes relatively little distortion, has been considered as a method for performing such hardening.
Laser irradiation over the entire inner circumferential surface of the cylinder is not a JM measure because it increases the number of machining steps, increases the cost, and increases the total cost.

Instead of hardening the entire surface, hardening is performed only around the top dead center of the piston top ring (Japanese Patent Laid-Open No. 53-137).
362), and one in which the area near the top dead center is dense and the other parts are coarse (see Utility Model Application Publication No. 57-84343).
However, these methods all involve hardening the entire circumference of the cylinder's inner circumferential surface, and the hardening effect is applied only to areas with a large amount of wear, effectively increasing wear resistance. , and it is not a sufficient solution to the problem of reducing the laser irradiation area as much as possible to perform processing in a short time.

The present invention was developed in view of these points, and when performing quench hardening using a laser, the laser irradiation is limited to only the part with the highest wear resistance, resulting in a shorter processing time and lower cost. The aim is to realize a laser-hardened cylinder that has a high wear resistance while achieving sufficient wear resistance. It is characterized by being quench hardened only in a certain range on the anti-thrust side.

That is, Figure 1 shows the results of measuring the amount of wear on the inner circumferential surface of the cylinder liner. In the figure, the width of the shaded area indicates the amount of wear. As can be seen, the wear on the inner peripheral surface of the cylinder liner is concentrated on the piston thrust side and anti-thrust side near the top ring top dead center, and in the present invention, the wear amount is reduced in this way. Laser irradiation is applied to the thrust side where the angle is large over a range of angle θA as shown in Figure 2, and on the anti-thrust side, laser irradiation is applied over a range of angle θB as shown in Figure 2. It hardens.

Fig. 3 shows the quenching pattern on the thrust side or anti-thrust side of the cylinder liner (1), and shows the quenching hardened part (2a) (2a) by laser irradiation.
b) is formed in a long linear shape in the sliding direction of the piston, and these quench hardened parts (2a) (2b) form the angle θA.
and θB in parallel in the circumferential direction.

In addition, these quench-hardened parts (2a) (2b) are almost concentrated near the top dead center of the piston ring, from near the top dead center of the top ring (3), which has the greatest wear, to near the top dead center of the lower piston ring (4). However, a part of the quench hardened portion (2b) is extended to the vicinity of the bottom dead center of the piston ring (4). Hardened parts (2a) and hardened parts (2b) having a length LIl extending to the bottom dead center of the lower piston ring (4) are alternately formed. This is because, from the point of view that the quench-hardened part is formed only in the part with the greatest amount of wear, only the length Ls is sufficient for the quench-hardened part, but all the quench-hardened parts (2a) ( If 2b) is kept at this length, the part below the top dead center of the piston ring will wear and a step will occur, so in order to eliminate this inconvenience, some of the hardened parts (2b) are extended. It is something that

In the above, the quenching range on the thrust side is the angle θ
It is desirable to form it in the range of A-90 to 120 degrees,
On the other hand, on the anti-thrust side, as shown in Figure 1,
The amount of wear is larger than that on the thrust side, so the angle θB=
It is formed in the range of 90 to 160 degrees. Furthermore, the lengths Ls and LIl, which are the hardening range in the piston sliding direction, are the sliding range of the piston ring, that is, in FIG. If the length to the bottom dead center of is LR, then the extended length Lj2 of the quench-hardened part (2a) is Lj2 = LR + Lm + Lm', and here, in Fig. 4, the quench-hardened part (2a) is (2a)
(2b) If the radius of the semicircular part at the upper end is R, then Lm≧
Therefore, L m = L m '≧0.5W W: Formed to the width of the quench-hardened part (2a) (2b), and the length of the quench-hardened part of the short part The length is L s ~0.1-0.5LA. Furthermore, in FIG. 4, each quench hardened part (2a
) W in (2b) is W=0. ．． 5 to 3 mm, the pitch P between each quench hardened part (2a) (2b) is P = 0.5 to 5 W, and the depth of the quench hardened part is greater than the allowable wear limit. be discovered.

FIG. 5 shows another embodiment of the present invention,
As shown in FIG. 1, the amount of wear on the thrust side and the anti-thrust side is greatest at the center of both, therefore, in the embodiment shown in FIG.
) (2a)... was performed by changing the length so that each center part was the longest and both ends were the shortest. In this case, the quench hardened part (
2a) The length may be changed sequentially so that (2a) becomes O.

FIG. 6 shows still another embodiment of the present invention, and in both FIGS. 3 and 5, both ends of the angles θA and θB in the circumferential direction ) (2a), whereas the longer extended quench-hardened part (
2b) It is possible to end the process with (2b), but if anything, the above-mentioned Figures 3 and 5 are preferable.

As explained above, according to the present invention, when hardening the inner peripheral surface of the cylinder or cylinder liner by laser irradiation, the hardening is performed only in a certain range on the piston thrust side and the anti-thrust side. Compared to the conventional method, which hardens the entire circumference, the laser irradiation time is shorter, the number of man-hours is reduced, the cost is lower, distortion can be reduced, and honing is easier. On the other hand, even if it is limited only to the thrust side and the anti-thrust side, its wear resistance is sufficient, and therefore, while ensuring sufficient wear resistance,
Furthermore, it is possible to obtain a remarkable effect that it can be implemented at low cost.

[Brief explanation of drawings]

FIG. 1 shows the wear amount of each part of the cylinder liner, where (A) shows the wear amount in the plane direction, (B) shows the wear amount in the longitudinal cross-sectional direction, and FIG. 2 shows the wear amount in the example of the present invention. FIG. 3 is an explanatory view showing the angle of the quenching range in the circumferential direction; FIG. 3 is a longitudinal cross-sectional view of the cylinder liner showing the quenching pattern on the thrust side or anti-thrust side; and FIG. 4 is a quench-hardened portion. 5 and 6 are longitudinal sectional views of a cylinder liner showing quenching patterns in other embodiments of the present invention, respectively. +11-m-cylinder liner, (2a) (2b)・
- Quench hardened part. Patent Applicant: Yanmar Diesel Co., Ltd. Representative Patent Attorney Hisayuki Tarumoto (A)
(B) Figure 3 Figure 4

Claims (1)

[Claims] A laser-hardened cylinder in which only a certain range on the piston thrust side and anti-thrust side is quenched and hardened when the inner peripheral surface of the cylinder or cylinder liner is hardened by laser irradiation.