JPH0643442Y2 - Camsyaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an engine camshaft.

(Prior Art) A camshaft is provided with a sliding contact portion with another member such as a journal portion or a cam portion, and it is necessary to improve wear resistance of these portions. Therefore, casting is performed using high hardness steel materials containing Ni, Cr, Mo, etc.

(Problems to be solved by the invention) However, when die casting is performed using a high hardness steel material, the hardness becomes HRC35-40 immediately after casting (as cast), and the end of the camshaft is not threaded. Machining cannot be done easily.

For this reason, the camshaft must be softened and heat treated for a long time (about 24 hours), machined, and then the cam portion must be quenched again.

Further, if the camshaft is hardened after being softened and machined, distortion, bending, or deformation due to quenching will occur.

Therefore, as disclosed in Japanese Patent Laid-Open No. 56-86664, a cam body and a journal body made of high hardness steel are set in a mold in advance, and a molten aluminum alloy is poured into the mold. The technology is known.

However, in the above-mentioned prior art, since the cam body and the journal body are cast in advance, the number of steps is increased and it takes time to manufacture the camshaft.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a hollow camshaft formed by casting a soft steel material at both ends of a shaft axis. A key groove for rotation prevention is provided, and a flange portion for retaining is provided on the base end side, and one of the soft steel materials to be machined has a solid structure, and the soft steel materials at both ends are hard steel materials. I made it by casting.

(Function) Set the cast stuff made of soft steel at the position that will be the end of the camshaft in the cavity, and then fill the cavity with the hard steel melt. The contact area is increased and the weldability is improved, and engagement in the axial direction is particularly ensured.

Further, the flange portion on the base end side similarly increases the contact area with the molten metal to enhance the weldability, and particularly ensures the engagement in the axial direction.

In addition, for example, in the case of performing processing such as hole processing, in the case of a hollow pipe, the original pipe hole becomes a pilot hole and hole processing is performed, so if the position where the pipe is wrapped around is shifted, it will be misaligned. It will be processed, but by making it a solid structure,
Problems such as misalignment are less likely to occur.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a die for casting a camshaft according to the present invention, in which a cavity (3) for casting the camshaft is formed between the left and right die (1), (2). A sand core (4) is set in the cavity (3), and is made of a soft steel material at the upper and lower parts of the sand core (4), that is, the positions which are the end portions of the cam shaft when the cam shaft is cast. The cast toy materials (5) and (6) are fixed.

By pouring the molten metal of hard steel into the cavity (3) as described above, the camshaft (7) shown in FIG. 2 is obtained. The hard steel material used as the main body of the camshaft (7) has a hardness of HRC45 to 60 in the as cast state and creates a fine and fine structure due to the cooling effect of the chiller and die. For example SMn, SMnC, SCr, SKH, SKD, SKS, S
UP, SUJ (both JIS) alloy materials with a large amount of carbon are used, and as the materials for forming the cast-in-stock materials (5) and (6), for example, carbon steel of about S20C to S40C, or to increase the strength to some extent A low alloy steel such as SCr, SCM, or SNCM may be used for this, and a normal, annealed or tempered steel is used. As shown in FIG. 3, the cast-in metal material (5) has a solid rod shape, and a flange portion (5a) for preventing the slip-out is formed at the base end of the cast-in metal material (5). As shown in FIG. 4, the outer peripheral surface has at least one key groove (in the embodiment of FIGS. 3 and 4, a spline shape is shown). By thus forming the outer peripheral surface of the cast-in member (5) in the shape of a key groove, the contact area with the molten metal at the time of casting is increased to improve the weldability, and even in the unlikely event of defective welding, the cast-in member is formed. (5) is prevented from rotating around the axis.

On the other hand, the cast stuffed material (6) has a tubular shape as shown in Fig. 5, a flange portion (6a) for preventing slipping is formed at the base end thereof, and the front half portion is further thickened for processing. I'm taking it for myself. As with the cast-in-guird material (5), the cast-in-gurged material (6) also has a key groove on the outer periphery to enhance the weldability.

As described above, when the camshaft (7) in which the cast-gurged materials (5) and (6) made of soft steel are casted on both ends is obtained, the cast-gurged materials (5) and (6) are Mechanically process, carve a screw part, etc., and attach other members such as pulleys to this end part.

(Effects of the Invention) As described above, according to the present invention, the end of the camshaft is formed by casting the cast-gurg material made of soft steel with the molten metal of the hard steel. After casting, the camshaft end can be machined by thread cutting or the like without performing the soft heat treatment, and the disadvantage that the distortion or the like occurs in the quenching after the softening heat treatment as in the conventional case is eliminated.

In addition, the key groove shape on the outer peripheral surface of the soft member and the flange portion on the base end side enhance the weldability with the molten metal during casting, so that the engagement in the axial direction can be ensured, and the prevention of slip-out is also ensured. Becomes

Furthermore, by making the portion of the soft member to be machined into a solid structure, it is possible to more accurately perform centering at the time of drilling.

[Brief description of drawings]

FIG. 1 is a sectional view of a die for casting a camshaft according to the present invention, FIG. 2 is a partial sectional view of a camshaft, FIG. 3 is a sectional view of a cast stuff, and FIG. 4 is a diameter of the camshaft. FIG. 5 is a sectional view of another cast doll material. In the drawings, (1) and (2) are molds, (3) is a cavity, (5) and (6) are cast stuffs, and (7) is a camshaft.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tadao Nagaoka 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (56) References JP-A-59-76655 (JP, A) JP-A-SHO 56-151210 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A hollow camshaft having a soft steel material cast around both ends of a shaft axis, wherein at least one non-rotating key groove is provided on the outer peripheral surface of the soft steel material to prevent slippage at the base end side. The camshaft is characterized in that while the flange portion is provided, one of the soft steel materials to be machined has a solid structure, and the soft steel materials at the both ends are surrounded by hard steel material.