JP2000329214A - Assembly camshaft and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the manufacturing process of an assembly camshaft assembled on a shaft main body by press-fitting in a plurality of assembly parts of cam piece or the like. SOLUTION: A plurality of columnar parts 5, 4, 3 are formed on a shaft main body 1 and are successively lessened in diameter toward one end of the shaft main body 1. Hole parts 21, 22, 23 of each assembly part 16, 17, 18 of cam piece 17 or the like are formed in a diameter each corresponding to the columnar parts 5, 4, 3, each columnar part 5, 4, 3 is press-fitted to each hole part 21, 22, 23. This press-fitting is performed successively from the columnar part of larger diameter. Splines 24, 25, 26 are formed in an internal peripheral surface of the hole parts 21, 22, 23, to make these splines 24, 25, 26 bite in the shaft main unit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft used for a general-purpose engine or the like and a method for manufacturing the same.

[0002]

In a conventional assembled camshaft, for example, as described in Japanese Patent Application Laid-Open No. H8-105307, almost the entirety of the camshaft is formed on the outer peripheral surface of a cylindrical shaft body having a constant diameter. While forming a plurality of projections in a spiral or concentric shape by rolling at the mounting position of the mounting component such as a cam piece, forming a plurality of splines on the inner peripheral surface of the hole of the mounting component, and mounting The shaft body is press-fitted into the hole of the component, and the spline of the assembly component is cut into the rolling projection of the shaft body, so that the assembly component is assembled to the shaft body. When assembling a plurality of parts to be assembled on one shaft body, the rolling of the protruding portion and the press-fitting of the assembled parts are repeated, and the assembled parts are sequentially assembled from one end side to the other end side of the shaft body. Go. This makes it possible to press-fit a plurality of parts to one shaft body. That is, although a protrusion having an outer diameter larger than its original outer diameter is formed on the outer peripheral surface of the shaft body by rolling, the shaft body is passed through the hole of the assembly component from the side where the protrusion is not formed yet. The component to be assembled can be moved to the protrusion and assembled to the protrusion. And
With such an assembling method using press-fitting, the manufacturing process can be simplified as compared with an assembling method using keyways and welding.

However, in the above-mentioned conventional method, since rolling and press-fitting are sequentially repeated, the number of steps for assembling increases, and efficient assembling work cannot be performed without a dedicated automatic device.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide an assembling camshaft which can simplify a manufacturing process and improve a joining strength, and a method of manufacturing the same.

[0005]

According to a first aspect of the present invention, there is provided a shaft body, and a plurality of assembled parts including a cam piece fixed to the shaft body in the axial direction. In the assembled camshaft attached to the shaft body by press-fitting the shaft body into a hole formed in the assembly part, the shaft body may be provided at one end side or It has a plurality of assembling parts whose diameters are sequentially reduced toward both end sides, and the plurality of assembling parts are assembled one by one to these assembling parts, and the holes of the assembling parts are A plurality of splines are provided on the inner peripheral surface, and an inner diameter of the spline is smaller than an outer diameter of a corresponding mounting portion of the shaft main body. Harder than the material, in which the assembled components of spline bites into the shaft body.

As described above, a plurality of mounting portions whose diameters are sequentially reduced toward one end or both ends of the shaft main body are formed, and mounting components are mounted one by one on these mounting portions. By attaching, it becomes possible to assemble a plurality of assembly parts into one shaft body by press fitting. Moreover, unlike the case where the assembly parts are assembled to the protruding portions formed on the shaft body by rolling, the plurality of assembly parts are
It can be formed on the shaft body in advance before all the components are assembled.

According to a second aspect of the present invention, in the assembled camshaft according to the first aspect of the present invention, the hardness of the material of the shaft body is set to 120 to 450 in HV, and the hardness of the material of the assembled part is set to 500 or more in HV. It was done.

[0008] This combination of hardness is appropriate to ensure that the splines of the assembled parts bite into the shaft body while ensuring the required rigidity of the shaft body.

According to a third aspect of the present invention, in the assembled camshaft according to the first or second aspect of the present invention, the base of the spline of the hole of the assembled part is formed into a smooth curved surface.

[0010] When the base of the spline has a smooth curved surface as described above, the strength of the spline particularly against a circumferential force is improved.

According to a fourth aspect of the present invention, a plurality of assembly parts including cam pieces are fixed to the shaft body by press-fitting the shaft body into a hole formed in the assembly part. In the method for manufacturing a camshaft, the shaft body is formed with a plurality of mounting portions having a diameter gradually decreasing toward one end or both ends thereof,
A hole having a diameter corresponding to each of the mounting portions of the shaft body is formed in each of the mounting parts, and an outer diameter of a corresponding mounting portion of the shaft body is formed on an inner peripheral surface of the hole. Forming multiple splines with smaller inner diameter than
Each of the mounting parts is sequentially mounted one by one from a large diameter to a small diameter in these mounting parts, and at this time, a shaft body is pressed into a hole of the mounting part, and each of the mounting parts is The spline of the assembled part is made to bite into a shaft body made of a material softer than the material described in (1).

As described above, a plurality of mounting portions whose diameters gradually decrease toward one end or both ends thereof are formed in advance on the shaft main body, and these mounting portions are changed from one having a larger diameter to a smaller one. By sequentially assembling each of the assembled parts one by one, it becomes possible to assemble a plurality of assembled parts into one shaft body by press-fitting.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an assembled camshaft according to the present invention and a method for manufacturing the same will be described below with reference to the drawings. Reference numeral 1 denotes a shaft body, and the shaft body 1 is made of a metal material such as steel. The shaft body 1 is substantially in the shape of a round bar, and has a plurality of columnar portions 2, 3, 4, 5, 6 coaxially arranged in the axial direction on the outer peripheral surface. Among these, at least the columnar portions 2, 3, 4, and 5 have different diameters, and the columnar portion 6 has a different diameter from the columnar portion 5. Therefore, steps 7, 8, 9,
There are ten. Of these cylindrical parts 2, 3, 4, 5, 6, the second cylindrical part 5 from the bottom in FIGS.
Has the largest diameter, and then the diameters of the columnar portions 2, 3, 4, 6 gradually decrease toward the upper side and the lower side. The diameter of the columnar section 6 may be different from or the same as the columnar sections 2, 3, and 4. 1 and 4, the second columnar portion 5 from the bottom is a first mounting portion to which the pulley 16 as a mounting component is fixed and mounted, and the third circular portion from the bottom is The columnar part 4 is a cam piece which is an assembly part.
17 is a second assembling portion to be fixedly assembled, and the fourth cylindrical portion 3 from the bottom is a third assembling portion to which the journal 18 as an assembling part is fixedly assembled. The cylindrical portions 2 and 6 at the upper and lower ends serve as journal portions (rotation support portions) when the shaft rotates.

The pulley 16, the cam piece 17 and the journal 18 are made of a metal material. The hardness of this material is higher than the hardness of the material of the shaft body 1. For example, the hardness of the material of the shaft body 1 is 86 in HRB.
While the hardness of the material of the pulley 16, the cam piece 17 and the journal 18 is 500 or more in HV, while it is 9898 (equivalent to 170 to 240 in HV). In addition, pulley 16, cam piece 1
The journal 7 and the journal 18 can be manufactured by an appropriate method such as die forging or cutting. In particular, powder metallurgy can be used to manufacture the cam piece 17. The hardness of these parts is determined by the splines 24,
Only the vicinity of the inner peripheral portion including 25 and 26 is required, and HV500 or less may be used in other portions.

The pulley 16, the cam piece 17 and the journal 18, which are the assembled parts, have holes 2 into which the corresponding columnar portions 5, 4, and 3 of the shaft main body 1 are press-fitted, respectively.
1, 22, and 23. The diameters of these holes 21, 22, and 23 are slightly larger than the outer diameters of the corresponding columnar portions 5, 4, and 3, respectively. A plurality (at least three) of splines 24, 25, 26 are formed on the inner peripheral surfaces of the holes 21, 22, 23, respectively, so as to protrude. These splines 24, 25,
The inner diameter of 26 corresponds to the corresponding cylindrical portion 5,
It is smaller than the outer diameter of 4,3. The difference between the inner diameter and the outer diameter, that is, the press-fitting allowance, is about 0.05 to 0.25 mm in radius. Therefore, the pulley 16 and the cam piece 17 are attached to the shaft body 1.
When the journal 18 is press-fitted, the material of the pulley 16, the cam piece 17 and the journal 18 is harder than the material of the shaft body 1,
The shaft body 1 is mainly plastically deformed and
The splines 24, 25 and 26 of the pulley 16, the cam piece 17 and the journal 18 will bite into the shaft. Further, as shown particularly in FIG. 3, the base of each spline 24, 25, 26 is formed in a smooth R-shaped curved surface 27.

Next, a method of manufacturing the assembled camshaft will be described. The cylindrical portions 2, 3, 4, of the shaft body 1
5 and 6 are formed in advance before assembling the pulley 16, the cam piece 17 and the journal 18 to the shaft main body 1. Also, pulley 16, cam piece 17 and journal
The 18 holes 21, 22, 23 and splines 24, 25, 26 are also formed before assembly to the shaft body 1.

Thereafter, the shaft body 1 is pressed into the pulley 16, the cam piece 17 and the holes 21, 22, and 23 of the journal 18 from the columnar portion 2 side by a press machine or the like, and the pulley 16, the cam piece 17 and the journal 18 are pressed. To the shaft body 1. At this time, first, the pulley 16 is mounted on the cylindrical portion 5 which is the first mounting portion of the shaft body 1. Next, the cam piece 17 is mounted on the cylindrical portion 4 which is the second mounting portion of the shaft body 1. Next, the journal 18 is mounted on the cylindrical portion 3 which is the third mounting portion of the shaft body 1. That is, assembling is sequentially performed from the cylindrical portion 5 having a larger diameter to the cylindrical portion 3 having a smaller diameter.
Then, when the shaft body 1 is pressed into the holes 21, 22, and 23 of the pulley 16, the cam piece 17 and the journal 18, the shaft body 1 made of a material softer than the material of the pulley 16, the cam piece 17 and the journal 18 is obtained. The pulley 16, the cam piece 17, and the splines 24, 25, 26 of the journal 18 bite into the shaft body 1 mainly due to plastic deformation. As a result, the pulley 16, the cam piece 17 and the journal 18 are securely and firmly fixed to the shaft main body 1, and especially the coupling force in the circumferential direction of the shaft is improved. In addition,
At the time of the assembling, since the diameters of the holes 21, 22, 23 are larger than the diameters of the columnar portions 2, 6 forming the journal portion, the columnar portions 2, 6 are not damaged.

As described above, the shaft main body 1 is stepped, and a plurality of cylindrical portions 5, 4 of which the diameters gradually decrease from one end to the other end are formed on the outer peripheral surface of the shaft main body 1. , 3 and the pulley 16, the cam piece 17 and the journal 18, which are parts to be assembled, are assembled one by one with these cylindrical parts 5, 4, 3, so that the cam piece 17, etc. A plurality of parts can be assembled by press fitting. Moreover, unlike the case where the assembling parts are assembled to the protruding portions formed on the shaft body by rolling, the columnar portions 5, which are a plurality of assembling parts,
4 and 3 can be formed on the shaft main body 1 in advance before all the components are assembled. Therefore, as compared with the case of performing rolling in particular, since the step required for the rolling is not required, manufacturing efficiency is improved. Since the processing of the shaft main body 1 and the step of press-fitting the mounting parts such as the cam pieces 17 to the shaft main body 1 can be separated, the manufacturing process can be further simplified, and the productivity is improved.

The hardness of the material of the shaft body 1 is set to HV.
, The required rigidity of the shaft body 1 as a camshaft can be secured. Meanwhile, pulley 16,
The hardness of the material of the cam piece 17 and the journal 18 in HV
Since it is set to 500 or more, the splines 24, 25, and 26 of the pulley 16, the cam piece 17 and the journal 18 can be securely pressed into the shaft body 1 by press-fitting, and the pulley 16, the cam piece 17 and the journal 18 Can be fixed securely.

Further, since the bases of the splines 24, 25 and 26 of the pulley 16, the cam piece 17 and the journal 18 are formed in a smooth R-shaped curved surface 27, the splines 24, 25 and 26 are particularly resistant to circumferential forces. Strength is improved. Therefore, the pulley 16, the cam piece 17, and the journal 18 can be more securely fixed to the shaft body 1.

According to one test result, the shaft body 1
800 to 100 when the press fitting allowance between
A pulling load of about 0kgf (corresponding to the axial coupling strength between the shaft body 1 and the cam piece 17) is obtained, and the press-in allowance is 0.13mm.
In the case of, a removal load of about 1200 to 1300 kgf was obtained, and in the case where the press-in allowance was set to 0.18 mm, a removal load of about 1600 to 1700 kgf was obtained. It was also confirmed that a torsional torque (corresponding to the rotational strength of the shaft body 1 and the cam piece 17 in the rotational direction) of 45 kgf · m or more was obtained for each of the press-fitting allowances of 0.08 mm, 0.13 mm, and 0.18 mm. .

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made. For example,
In the above embodiment, three assembly parts are incorporated in one shaft body, but the number of assembly parts to be assembled in one shaft body is not limited to three. Assembling portions having different diameters are formed on the shaft body at least by the number of the assembly components. In the above-described embodiment, the components to be assembled are assembled only from one end of the shaft main body. However, the components to be assembled may be assembled from both ends of the shaft main body. In this case, it is assumed that the diameter of each assembly portion of the shaft main body is gradually reduced from the intermediate portion of the shaft main body toward both end sides. However, the assembling process can be further simplified if the assembling is performed from only one direction.

FIG. 6 shows an example of an assembled camshaft assembled from both ends. In this example, the shaft main body 1 has two columnar portions 3 and 2 whose diameters gradually decrease from the columnar portion 4 having the largest diameter toward the upper end side. It has a columnar portion 5 having a smaller diameter than the columnar portion 4. Therefore, the steps 7, 8, 9
There are three. The cylindrical portions 2 and 5 at the upper and lower ends constitute a journal portion. On the other hand, the illustrated lower part of the columnar part 4 is a first mounting part to which the pulley 16 is mounted, and the upper part of the columnar part 4 is the second mounting part to which the cam piece 17 is mounted. The top 3 of the column is the journal
Reference numeral 18 denotes a third mounting portion to be mounted. At the time of manufacture, the cam piece 17 and the journal 18 are assembled to the shaft body 1 from the upper side in the figure, and the pulley 16 is assembled to the shaft body 1 from the lower side in the figure.

[0024]

According to the assembled camshaft according to the first aspect of the present invention, a plurality of mounting portions whose diameters gradually decrease from one end to the other end are formed in the shaft body, and these mountings are performed. By assembling a plurality of assembly parts including cam pieces into the parts one by one by press-fitting, the processing of the shaft body and the step of assembling the assembly parts to the shaft body by press-fitting can be separated, so the manufacturing process can be simplified. , And productivity is improved. Also, the internal spline of the assembled part
Because it is harder than the shaft body, it bites into the shaft body,
In particular, it is possible to secure the bonding strength in the circumferential direction.

According to the assembled camshaft of the second aspect, in addition to the effect of the first aspect, the hardness of the material of the shaft body is set to 120 to 450 in HV, and the hardness of the material of the assembled part is set to HV. Since the required rigidity of the shaft main body is secured, the spline of the assembly part can be reliably pressed into the shaft body by press fitting, and the assembly part can be securely fixed to the shaft body.

According to the assembled camshaft of the third aspect of the present invention, in addition to the effects of the first or second aspect of the present invention, the base of the spline of the hole of the assembled part is formed in a smooth curved surface, so that the camshaft is particularly suitable. The strength of the spline against circumferential forces can be further improved.

According to the method of manufacturing an assembled camshaft according to the fourth aspect of the present invention, a plurality of assembling portions whose diameters gradually decrease from one end side to the other end side are previously formed on the shaft main body. By sequentially assembling each of the parts to be assembled one by one from a large diameter to a small one by press-fitting, the manufacturing process can be simplified and the productivity is improved. In addition, since the inner diameter spline of the assembled component is harder than the shaft main body, the spline bites into the shaft main body, and particularly, the connection strength in the circumferential direction can be secured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an assembled camshaft according to the present invention.

FIG. 2 is a perspective view of the same.

FIG. 3 is an enlarged sectional view showing the vicinity of the spline according to the first embodiment;

FIG. 4 is a side view of the shaft main body.

FIG. 5 is a front view of a cam piece that is an assembly component of the same.

FIG. 6 is a sectional view showing another embodiment of the assembled camshaft of the present invention.

[Explanation of symbols]

 1 Shaft body 3,4,5 Cylindrical part (assembly part) 16 Pulley (assembly part) 17 Cam piece (assembly part) 18 Journal (assembly part) 21,22,23 Hole 24,25,26 spline

Claims (4)

[Claims] 1. A vehicle comprising: a shaft body; and a plurality of mounting parts including a cam piece fixed to the shaft body side by side in an axial direction thereof, wherein the mounting parts have holes formed in the mounting part. In the assembled camshaft assembled to the shaft main body by press-fitting the shaft main body into the shaft main body, the shaft main body has a plurality of mounting portions whose diameters gradually decrease toward one end or both ends thereof, The plurality of mounting parts are mounted one by one on these mounting parts, and the hole of the mounting part has a plurality of splines on an inner peripheral surface, and the inner diameter of the splines is the shaft body. Is smaller than the outer diameter of the corresponding mounting part, the material of the mounting part is harder than the material of the shaft body, and the spline of the mounting part is An assembled camshaft, which bites into the main body. 2. The material of the shaft body has a hardness of HV.
120-450, and the hardness of the material of the assembled part is HV
The assembled camshaft according to claim 1, wherein the number is 500 or more. 3. The assembly camshaft according to claim 1, wherein the base of the spline in the hole of the assembly part has a smooth curved surface. 4. A method of manufacturing an assembled camshaft in which a plurality of assembled parts including a cam piece are fixed to the shaft body by press-fitting the shaft body into a hole formed in the assembled part. In the shaft main body, a plurality of mounting portions whose diameters gradually decrease toward one end side or both end sides thereof are formed, and each of the mounting components has a diameter corresponding to each mounting portion of the shaft main body. While forming a hole having a, on the inner peripheral surface of this hole,
A plurality of splines having an inner diameter smaller than an outer diameter of a corresponding assembling portion of the shaft main body are formed, and the assembling parts are sequentially attached to these assembling portions one by one from a larger diameter to a smaller one. At this time, the shaft body is press-fitted into the hole of the assembly part, and the spline of the assembly part is cut into the shaft body made of a material softer than the material of each of the assembly parts. Manufacturing method of assembled camshaft.