JPH0131424Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a camshaft forming fixture used when assembling a camshaft and a cam journal by a cold tube expansion method.

Conventionally, a method is known in which a hollow camshaft, a cam and a journal in which an insertion hole is formed are each manufactured separately, and the camshaft, cam, and journal are assembled by a cold tube expansion method.

By the way, as a method for assembling the cam to the camshaft as described above, for example, Japanese Patent Application Laid-Open No. 58-70011
As disclosed in the publication, the cam profile is positioned using a split-shaped fixing jig, the camshaft is inserted into the insertion hole formed in the cam, and then the camshaft is expanded using a tube expansion member. The cam was fixed.

However, in the case of such a conventional cam fixing jig, it is formed in advance to allow for errors in the curved surface of the cam profile and to create a gap between the fixing jig and the cam profile. There was a problem in that the cam rotated or moved after positioning, making it impossible to perform accurate assembly work.

Furthermore, variations in the machining accuracy of the cam profile have a large effect on the positioning accuracy of the cam in the rotational direction, and as a result, it has been necessary to correct it in the polishing process after assembly.

Furthermore, the abutment surface of the fixing jig had to be machined in accordance with the curvature of the cam profile, which required a great deal of time and effort, leading to increased costs.

This idea was devised by focusing on the conventional problems, and its purpose is to be able to accurately position the cam body on the fixing jig, and to improve productivity by eliminating the need for polishing the cam profile. The present invention provides a fixing jig for molding a camshaft, which can improve the camshaft, cam main body, and journal, and also improves the workability of assembling the camshaft, cam body, and journal.

In order to achieve the above object, this invention forms a recess into which the cam profile of the cam body fits on the abutting surface of the split fixture, and the end face of this recess has a
The gist is that a locking portion is formed to engage an engaging portion formed on the end surface of the cam body.

Embodiments of this invention will be described below based on the accompanying drawings.

FIG. 1 shows an exploded perspective view of a fixture 1 for molding a camshaft body (not shown) according to this invention, in which 1a is an upper die, 1b is a lower die, 2 is a cam body, 3 is a cam profile, 4 is a hollow camshaft.

A camshaft insertion hole 6 with serrations 5 formed on the inner wall is formed in the center of the cam body 2, and a positioning protrusion 7 is integrally formed on one side 2a of the cam body 2. . An engaging portion 8 notched in parallel is formed on the outer circumferential surface of the positioning convex portion 7 .

On the other hand, the fixing jig 1 for positioning the cam body 2 has an upper die 1a and a lower die 1b as shown in FIG.
Recesses 9a, 9 formed in contact surfaces S1, S2 with
Locking portions 10a and 10b that engage with the convex portion 7 and the engaging portion 8 of the cam body 2 are formed on one side of the cam body 2. The locking portions 10a and 10b are formed in parallel to correspond to the parallel notched engaging portion 8, and when positioning a plurality of cam bodies 2 at the same time with a phase shift, as shown in the figure. The locking portions 10a and 10b are sequentially formed at predetermined angles.

Next, a method for positioning the cam body 2 using the fixing jig 1 as described above and a method for forming the camshaft body will be described.

First, the recess 9 formed in the contact surface S2 of the lower mold 1b
For each of b, a plurality of cam bodies 2 are manufactured through each process of rough processing → quenching → polishing → cutting.
Then, the engaging portion 8 of the cam body 2 is engaged with the locking portion 10b of the recess 9b for positioning.

Next, the contact surface S1 of the upper mold 1a is fitted as shown in FIG. 1, and the locking portion 10a of the upper mold 1a is engaged with the engaging portion 8 of the cam body 2. After the positioning of each cam body 2 is completed in this manner, the upper die 1a and the lower die b are tightened and fixed using fasteners such as bolts (not shown). Then, the hollow camshaft 4 is inserted into the camshaft insertion hole 6 formed in the center of the cam body 2. Further, as shown in FIG. 3, a male member 11 for tube expansion is pushed in from one end of the camshaft 4 using a hydraulic press (not shown), thereby expanding the camshaft 4 and releasing the cam body 2.
The camshaft 4 is fixed by biting into the serrations 5 formed on the inner wall of the camshaft 4. Such an assembly operation is a so-called cold tube expansion method for the camshaft body, and the journal (not shown) is also fixed by such a method.

As described above, without positioning using the cam profile 3 of the cam body 2, the engagement portion 8 formed on one side 2a of the cam body 2 and the upper die 1a of the fixing jig 1 are connected.
and the locking portions 10a, 10 formed on the lower mold 1b.
Since the cam body 2 is positioned using ``b'', the cam body 2 does not move or rotate after positioning, and therefore, accurate assembly work can be performed.

In addition, as in the embodiment of this invention, the cam body 2, camshaft 4, and journal are manufactured separately in advance and assembled using the cold tube expansion method, so that the machining accuracy of the cam profile 3 is good, as shown in FIG. As shown in FIG. 2, a plurality of cam bodies 2 are connected and subjected to rough machining, hardening, and polishing, and then are cut at the positions shown by dotted lines, so that productivity can also be improved.

In this invention, as described above, a recess into which the cam profile of the cam body fits is formed on the abutment surface of the split fixture, and an engaging portion formed on the end face of the cam body is formed on the end face of this recess. Since a locking part is formed to engage the cam body, it is possible to position the cam body in the fixing jig with high precision.Also, since the cam body is manufactured separately, it is possible to manufacture multiple cam bodies at the same time.
Not only can it be manufactured at low cost, productivity can be improved by eliminating the need for polishing the cam profile, and it is also effective in improving the workability of assembling the camshaft, cam body, and journal.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view of a fixing jig that implements this invention, Figure 2 is a perspective view of the lower mold, Figure 3 is an explanatory diagram of the cold pipe expansion method, and Figure 4 is shown along the - line in Figure 2. 5 is a sectional view taken along the - line in FIG. 2, FIG. 6 is a sectional view taken along the - line in FIG. 2, and FIG. 7 is an explanatory view showing a method of manufacturing the cam body. 1...Fixing jig, 1a...Upper mold, 1b...Lower mold, 2...Cam body, 8...Engaging portion, 9a, 9b
...Recessed part, 10a, 10b...Locking part, S1, S
2...Abutment surface.

Claims (1)

[Scope of utility model registration request] A recess into which the cam profile of the cam body is fitted is formed on the abutment surface of the split-shaped fixing jig, and a locking portion which engages with the end face of the recess an engaging part formed on the end face of the cam body. A fixing jig for forming a camshaft, characterized by forming a camshaft.