JPH094421A - Manufacture of valve lifter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve manufacturing efficiency of a valve lifter, reduce a cost, and improve abrasion resistance of an abutting portion. SOLUTION: Iron-derived mother material is subjected to cold forging (P1). Afterward, annealing and bonderizing treatment is applied thereto (P2). An outer shape of a valve lifter is molded by cold pressing (P3). The product is washed (P4). Next, an outer peripheral surface is ground for preparing outer diameter measurement of a skirt (P5). Total processing of inner and outer peripheral surfaces is carried out (P6). Next, a fitting groove is cut out on the top surface of a crown (P7). Then, high frequency quenching is carried out on an abutting portion alone for improving hardness (P8). The abutting portion is ground (P9). Whole of the member is washed and subjected to antirust treatment (P10). It is then inspected (P11), and delivered (P12).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a valve lifter used in, for example, an internal combustion engine of an automobile.

[0002]

2. Description of the Related Art As is well known, in a DOHC (double overhead cam) type valve operating mechanism used in, for example, an automobile internal combustion engine, a cam 2 integrally provided on a cam shaft 1 as shown in FIG. A direct acting valve lifter 4 for transmitting the lift of the cam 2 to the intake valve 3 is provided between the intake valve 3 and the intake valve 3.

As shown in the figure, the valve lifter 4 is made of steel and has a cylindrical shape with a lid, and has a cylindrical skirt portion 7 that slides in a guide hole 6 of a cylinder head 5, and an upper portion of the skirt portion 7. A disc-shaped crown portion 8 integrally provided on the inner circumference is provided. Further, the crown portion 8 has a skirt portion 7 on the upper surface.
A fitting groove 9 defined by the upper end of the cam 2 is formed, and a disc-shaped shim 10 with which the outer peripheral surface of the cam 2 slides is press-fitted and fixed to the fitting groove 9. Further, at the inner surface of the crown portion 8, that is, at the center position on the rear surface side opposite to the bottom surface of the fitting groove 9, a small-diameter disk-shaped contact portion 11 that contacts the top surface of the valve stem 3a of the intake valve 3 is integrally formed. It is provided.

In order to manufacture the valve lifter 4, generally, the valve lifter 4 is molded through a series of steps shown in FIG. To explain the outline, first, the iron base material (SCM
415H material) is cold forged (P1) so that the contact portion 11 has a shaft diameter of 7 mm, and this is annealed and bonded (P1).
2) Next, cold forging is performed to secure the overall hardness (P
3). Subsequently, after cleaning (P4), the outer shape of the skirt portion 7 is adjusted by grinding (P5), and further, the entire inner and outer surfaces including the upper surface of the crown portion 8 and the outer surface of the contact portion 11 are ground to shape. (P6). Further, a notch is formed on the upper surface of the crown portion 8 to form the fitting groove 9 (P7). afterwards,
In order to increase the hardness, the entire valve lifter 4 is carburized and quenched (P8), and subsequently, in order to obtain the accuracy of the outer diameter dimension deformed by the heat treatment, finish contour grinding is performed (P9), and the dimensions such as the inner diameter are also performed. In order to obtain accuracy, the inner surface of the fitting groove 9 and the outer surface of the contact portion 11 are finish-ground (P1
0) (P11), followed by cleaning and rustproofing the entire valve lifter 4 (P12), inspection (P13), and shipment (P14).

[0005]

However, in the conventional method of manufacturing the valve lifter 4, the valve lifter 4 is increased in order to increase the hardness in the manufacturing process (P8).
The whole is heat-treated by carburizing and quenching, and then finish contour grinding (P9) and finish grinding (P10) (P11) of the inner surface of the fitting groove 9 and the outer surface of the contact portion 11 are performed again.

As described above, since the whole grinding process must be performed again after the heat treatment, the manufacturing man-hour is inevitably increased, which not only lowers the manufacturing work efficiency but also increases the equipment cost and raises the cost. Is invited.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances.
A method of manufacturing a valve lifter, wherein a crown portion on which a cam of a cam shaft slides is provided on an upper portion of a skirt portion, and an abutting portion that abuts a valve stem of an intake / exhaust valve is formed on a back surface side of the crown portion. Therefore, after cold forging the cold forged base material, the outer diameter is trimmed to adjust the outer shape, and then the dimensions of each part are adjusted by total machining of the entire inner and outer peripheral surfaces, and then the hardness is obtained. Heat treatment is applied only to the contact part,
Next, a method for manufacturing a valve lifter, characterized in that the corresponding contact portion is subjected to finish grinding.

According to a second aspect of the present invention, a crown portion is provided on an upper portion of the skirt portion, with which the cam of the cam shaft is slidably contacted, and a contact portion contacting the valve stem of the intake / exhaust valve is provided on the back surface side of the crown portion. Is a method for manufacturing a valve lifter in which a medium carbon steel base material is compression-formed into a valve lifter shape by cold forging, and then heat treatment is applied only to the portion corresponding to the contact portion to obtain hardness. After that, the entire outer diameter finish grinding process is performed, and then the contact portion finish polishing process is performed.

The invention of claim 3 is characterized in that the heat treatment of the contact portion is carried out by induction hardening.

According to the first aspect of the present invention, after the entire grinding of the entire inner and outer peripheral surfaces of the valve lifter, the entire valve lifter is not heat-treated as in the conventional case, but only the abutting portion that needs to be increased in hardness. Since heat treatment is performed, and only the contact portion is thereafter subjected to finish grinding, the number of steps can be reduced as compared with the conventional manufacturing steps, and the manufacturing work efficiency can be improved.

According to the invention of claim 2, in addition to the function of the invention of claim 1, since the base material is formed of medium carbon steel material whose composition is adjusted, the valve lifter is compared with low carbon steel or alloy steel. The overall hardness can be increased and the cold forgeability can be improved to the alloy steel level.

Further, according to the third aspect of the present invention, since the heat treatment of the abutting portion is performed by induction hardening instead of carburizing and quenching, the abutting portion is hardened not only on the surface but also inside. Therefore, the hardness of the contact portion can be further increased, and the durability can be improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 4 shows a valve lifter 4 applied to the present invention. The valve lifter 4 is used on the intake valve side as in the conventional case and is entirely made of an iron-based base material and slides in a guide hole of a cylinder head. A cylindrical skirt portion 7, a disc-shaped crown portion 8 integrally formed on the upper portion of the skirt portion 7, and a shim 10 which is a disc-shaped sliding contact member formed on the upper surface of the crown portion 8. And a disc-shaped contact portion 11 integrally formed at the center of the inner surface of the crown portion 8.

The valve lifter 4 is manufactured by a series of steps shown in FIG. 1. First, in the first step (P1), the base material is compression-formed by cold forging, and the second step is performed. In (P2), this is annealed and heat-treated to recrystallize it, and is also subjected to a bonder treatment. Next, the third
In the step (P3), the outer shape of the valve lifter is formed by cold heading, and subsequently, it is washed in the fourth step (P4).
Next, in the fifth step, the outer peripheral surface of the skirt portion 7 is ground to adjust the outer diameter dimension, and further, in the sixth step (P6), the entire inner peripheral surface including the outer peripheral surface and the contact portion 11 is ground to outside and inside. Adjust the diameter. Further, in the seventh step (P7), the upper surface of the crown portion 8 is cut into a circular shape to form the fitting groove 9.

Next, in the eighth step (P8), the contact portion 11
Induction hardening for a short period of time is performed on only this, thereby increasing the hardness of the corresponding contact portion 11. Then, the ninth
In the step (P9), the quenched contact portion 11 is ground to adjust the outer diameter and the wall thickness again.

Further, in the tenth step (P10), the valve lifter 4 is washed and rustproofed, and the manufacturing work is completed. After that, the dimensions of each part and the inside are inspected (11th process (P11)) and shipped (12th process (P11)).
12)).

As described above, in this embodiment, the seventh step (P
The heat treatment performed after the fitting groove 9 is cut out in 7) to adjust the depth and the like is performed not on the valve lifter 4 as a whole.
Since only the local contact portion 11 is performed, the heat treatment can be performed in a short time and the heat treatment can be performed inline. Therefore, workability of heat treatment is improved. Further, the influence of heat on the entire valve lifter 4 is reduced, and the deformation of the skirt portion 7 is suppressed. Further, the partial heat treatment prevents the skirt portion 7 from being completely hardened, and the impact strength is less deteriorated. Therefore, the skirt portion 7 and the like can be further thinned and the weight can be reduced.

Moreover, the subsequent grinding process (the ninth step) for adjusting the dimensional error due to the heat treatment is performed by the contact portion 11
Since only this is required, the grinding work becomes easy. As a result, combined with the short-time heat treatment in the seventh step, the number of work steps can be reduced and the molding work efficiency can be improved.

Further, the heat treatment of the seventh step is performed by induction hardening, not by conventional carburizing and quenching, so that not only the surface of the contact portion 11 but also the inside can be quenched. Higher hardness (about 60H
It is possible to improve wear resistance and durability. Further, since the hardness of the skirt portion 7 and the like is about 25 HRC, it becomes possible to perform high-speed cutting of each of these portions, and in this respect also, the manufacturing workability is improved.

FIG. 2 shows a second embodiment of the manufacturing method only for the valve lifter according to the present invention. The outer diameter grinding process of the fifth step (P5) in the first embodiment is not performed here, but the seventh embodiment is used. After induction hardening of only the contact portion 11 in the step (P7), the outer diameter dimension of the skirt portion 7 is adjusted by sizing in the eighth step (P8). Thereby, the contact portion 11
By adjusting the change in the outer diameter of the skirt portion 7 due to the heat treatment, it is possible to obtain a more accurate outer diameter dimension of the skirt portion 7. In addition, other configurations (processes)
Since it is the same as the first embodiment, the same operational effect as that of the first embodiment can be obtained.

In each of the embodiments, the skirt portion 7 is not heat-treated, but since the skirt portion 7 simply slides in the guide hole, the occurrence of wear or the like is extremely small.
Problems such as wear do not occur.

Further, since the crown portion 8 is in sliding contact with the cam by the wear-resistant shim 10, the problem of wear or the like does not occur.

FIG. 3 shows a third embodiment of the method for manufacturing a valve lifter according to the present invention. In this embodiment, the base material of the valve lifter 4 shown in FIG. 4 is a medium carbon steel material whose components are adjusted. . That is, this base material has a carbon C content of 0.
45% by weight or more of carbon steel as a base, 0.15% by weight or less of silicon Si and 0.25% by weight or less of manganese Mn
And, it contains less than 0.2% by weight of chromium Cr.
Further, 20 ppm or less (0.002%) by weight of boron B is added.

To manufacture the valve lifter 4, a series of steps shown in FIG. 3 are carried out.
In the step (P1), an annular thick plate valve lifter base material (ingot) based on the carbon steel is compression-formed into a shape as shown in FIG. 4 by cold forging, and then the second
In the step (P2), only the contact portion 11 is subjected to induction hardening for a short time, thereby increasing the hardness of the contact portion 11. Then, in the third step (P3), the outer peripheral surface of the skirt portion 7 is finish ground to adjust the outer diameter dimension, and in the fourth step (P4), the upper surface of the crown portion 8 of the valve lifter 4 is cut into a circular shape. Machining is performed to form the fitting groove 9, and the length dimension is adjusted by grinding the bottom surface of the fitting groove 9 and the periphery of the outer peripheral wall. Further, in the fifth step (P5), the lower surface 11a of the contact portion 11 (boss portion) is finished by grinding.
Then, in a sixth step (P6), the valve lifter 4 is washed and rustproofed, and the manufacturing work is completed. After that, in the seventh step (P7), the dimensions of each part and the inside are inspected, and the shipping work is performed in the eighth step.

Therefore, in this embodiment as well, as in the first embodiment, the heat treatment by induction hardening is performed not on the entire valve lifter 4 but only on the local contact portion 11, so that the heat treatment can be performed in a short time. Therefore, the same effect as the above can be obtained.

Moreover, the base material of the valve lifter 4 is a medium carbon steel material, and the content of alloying elements such as Si and Mn is suppressed with respect to the amount of carbon C, so that the hardness is higher than that of low carbon or alloy steel. It goes without saying that the cold forgeability can be improved to the level of alloy steel.

Since boron B is added, the induction hardenability is improved, and on the other hand, since boron has little influence on the deformation resistance, cold forgeability does not deteriorate.

[0029]

As is apparent from the above description, according to the method for manufacturing a valve lifter of the present invention, the heat treatment for increasing the hardness is performed only on the abutting portion. There is no need for outer diameter grinding or fitting groove processing for dimension adjustment. Therefore, the heat treatment time can be shortened, the number of manufacturing steps can be reduced, and the manufacturing work efficiency can be improved as a whole. Further, since the grinding process is unnecessary, the equipment cost and the manufacturing cost can be greatly reduced.

Further, according to the second aspect of the present invention, since the valve lifter base material is the medium carbon steel material, the hardness of the whole can be increased as compared with the low carbon steel or the alloy steel, and it is of course possible to cool the valve. It is possible to improve the forgeability between alloys to the level of alloy steel. As a result, it is possible to secure sufficient overall rigidity while suppressing a decrease in manufacturing work efficiency.

Further, since the heat treatment of the abutting portion is performed by induction hardening, the hardness can be further increased, and as a result, wear resistance and durability can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a manufacturing process showing a first embodiment of the present invention.

FIG. 2 is a block diagram of a manufacturing process showing a second embodiment of the present invention.

FIG. 3 is a block diagram of a manufacturing process showing a third embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing a valve lifter used in each example.

FIG. 5 is a cross-sectional view showing a state in which a conventional valve lifter is applied to an intake valve operating mechanism.

FIG. 6 is a block diagram showing a conventional manufacturing process.

[Explanation of symbols]

 4 ... Valve lifter 7 ... Skirt part 8 ... Crown part 9 ... Fitting groove 10 ... Shim (sliding contact member) 11 ... Contact part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiji Tsuruta 1370 Onna, Atsugi, Kanagawa Pref., Unisia Jecs Co., Ltd. (72) Inventor Kenji Suzuki, 1370, Atsugi, Kanagawa Pref., Unisia, Jecs Co., Ltd. (72) Inventor Susumu Shin Izumi JEX Co., Ltd. 1370 Onna, Atsugi City, Kanagawa Prefecture

Claims (3)

[Claims] 1. A valve in which a crown portion on which a cam of a camshaft slides is provided on an upper portion of a skirt portion, and an abutting portion which abuts a valve stem of an intake / exhaust valve is formed on a back surface side of the crown portion. A method of manufacturing a lifter, in which after cold forging a cold forged base material, the outer shape is adjusted by external diameter grinding, and then the dimensions of each part are adjusted by total machining of the entire inner and outer peripheral surfaces, and then, A method for manufacturing a valve lifter, characterized in that only the abutting portion is heat-treated to obtain hardness, and then the abutting portion is subjected to finish grinding. 2. A valve in which a crown portion on which a cam of a cam shaft slides is provided on an upper portion of a skirt portion, and an abutting portion which abuts on a valve stem of an intake / exhaust valve is formed on a back surface side of the crown portion. A method of manufacturing a lifter, in which a base material of a medium carbon steel material is compression-molded into a valve lifter shape by cold forging, and then heat treatment is applied only to a portion corresponding to the contact portion to obtain hardness, and then A method of manufacturing a valve lifter, characterized in that the entire outer diameter finish grinding is performed, and then the contact portion is finish grinding. 3. The method of manufacturing a valve lifter according to claim 1, wherein the heat treatment of the contact portion is performed by induction hardening.