JPS6297722A - Production of cam shaft - Google Patents

Abstract

PURPOSE:To prevent the crack generation of a cam piece and to increase the phase accuracy by positioning a hollow piece by providing an engaging part on the cam piece and forming die in the production method bulge-forming the cam piece and hollow shaft. CONSTITUTION:The upper and lower dies 1, 2 are separated in order to fix a hollow shaft S, hollow cam piece C1, C2 and hollow journal piece J by using a bulge-forming die. The split die 8b, 8a respectively fitting to the base side and nose side of the piece C1 are ascended and descended then. Stem presser 30a, 30b are ascended as well. Then the piece C1 is fitted onto the die 8b, the base side of the piece C1 is placed on an fitting part 21b and the engaging part 24, 21d respectively provided on the die 8b are fitted as well. The phase decision of the piece C1 and the positioning in the thrust direction can be performed simultaneously. Similar works are performed on the piece C2 as well and after setting up the piece J with its fitting the die 1 is descended, a shaft S is fitted to the hollow aperture, etc., of each piece and is expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention 1 (Field of Industrial Application) This invention provides a camshaft suitable for manufacturing a camshaft used for driving intake and exhaust valves of an internal combustion engine, for example. This relates to a manufacturing method.

(Prior art) Conventionally, the method for manufacturing this type of camshaft is as follows:
One hollow shaft and a predetermined number of hollow cam pieces and hollow journal pieces are fitted together, and by feeding pressurized fluid into the hollow shaft to expand the tube, the hollow cam piece, the hollow journal piece, and the hollow shaft are connected. There is a bulge forming method that fixes the

In this bulge forming method, for example, there is an idea to use the forming mold shown in Fig. 8 (Utility Application No. 59-168
No. 302), this mold is an upper mold 101 consisting of a one-piece mold.
and a lower die 102, each of the upper die 101 and the lower die 102 has a flat portion F1 that matches the flat portions Fl and F2 of the cam profile of the hollow cam piece Cl+C2.
+ Each hollow cam piece C,,C2 based on F2
A tapered groove-shaped positioning receiving chamber part Iota for positioning.

102a is provided.

And hollow cam piece C1+ C2 and hollow shaft S
When fixing the hollow cam piece Cl + C2 to the lower mold 102, the upper mold 101 is lowered to fit and fix the hollow cam piece CI + 02, and then the hollow cam piece Cl + C2 is fitted into the hollow shirt S. The hollow cam pieces C, C2 and the hollow shaft S are fixed by applying pressure and expanding the pipe by supplying pressurized fluid.

(Problems to be Solved by the Invention) When manufacturing a hollow camshaft using such a bulge mold, usually the hollow cam pieces C, C2
However, if the fitting precision of the hollow cam pieces C1 and C2 to the lower die 102 is poor.

After that, when fitting and fixing the upper mold 101, the hollow cam piece C
1* There is a possibility that cracks may occur in C2, the phase accuracy of each cam piece C1 + C2 of the hollow camshaft may not be good in the fixed state after bulge forming, and the hollow cam piece does not have pressure in the thrust direction. There were some problems, such as the possibility that the positional accuracy in the thrust direction would be low.

This invention has been made in view of the above-mentioned conventional technology, and eliminates the possibility of cracks occurring in the hollow cam piece when fixing the hollow cam piece to a mold.
The purpose of the present invention is to provide a method for manufacturing a camshaft that has high phase accuracy of each cam piece after assembly, high positional accuracy in the thrust direction, and can improve the quality of a hollow camshaft after bulge forming. There is.

[Structure of the Invention] (Means for Solving the Problems) A method for manufacturing a camshaft according to the present invention includes a method for manufacturing a camshaft in which a predetermined number of hollow cam pieces and a hollow shaft are fixed together by bulge forming to manufacture a camshaft. A mold engaging part is provided in a part of the bulge forming mold, a cam piece engaging part that can be engaged with the mold engaging part is provided in a part of one of the split molds for bulge forming, and the hollow cam piece is attached to the one split mold. By fitting both of the engaging parts in an engaged state, the hollow cam piece is phased and positioned in the thrust direction, and then the hollow cam piece is moved to the one split mold using the other split mold for bulge forming. The feature is that the bulge is formed while being sandwiched between and fixed.

In an embodiment of the present invention, the mold engaging portion provided in a part of the hollow cam piece has a circular shape on the surface portion of the hollow cam piece with a diameter of 2 mm or more and 10 mm or less, and a depth of 1 mm or more and 5 mm or less. In another embodiment of the present invention, the mold engaging portion provided in a part of the hollow cam piece has a shape on the surface of the hollow cam piece with a diameter of 2 mm or more and 10 mm or less. It can be made of an elongated hole shape with a semicircle at both ends and a straight line connecting the two ends, and a length of 5 mm or more and 15 mm or less, and a long hole recess with a depth of 1 mm or more and 5 mm or less. Further, the cam piece engaging portion provided on a part of the one split mold may be a pin-shaped convex portion having a cylindrical shape with a diameter of 2 mm or more and 10 mm or less and a height of 1 mm or more and 5 mm or less.

FIG. 1 is a diagram showing a bulge mold used in one embodiment of the present invention.

In the figure, 1 is an upper mold for bulge forming, 2 is a lower mold for bulge forming, 3a and 3b are plugs, 4 is a pressurized fluid feed pipe provided in one of the plugs 3a, C 凰 and C2 are predetermined A hollow cam piece having a cam profile shape, J is a perfectly circular hollow journal heath, and S is a hollow shaft.

Among these, the upper mold 1 includes a base plate 5 and split molds 6a, 7a, and 8a for bulge forming.

9a, 10a, lla, 12a, and 13a, and is fixed to the upper press ram 15 via an adapter plate 14. On the other hand, the lower mold 2 has a base plate 16
and split molds 6b, 7b, 8b, 9b, 10 for bulge forming.
b,llb.

12b and 13b. In this case, the split molds 8a, 8b, 1 that fit with the hollow cam pieces C, , C2
0a, 10b and the split molds 12a, 12b that fit with the hollow journal piece J.

Each plunger (18a) as described later.

18b), it can be raised and lowered.

Then, as shown in FIGS. 1 to 5, the split mold 8a
has a cam piece fitting part 21a, and the one-piece mold 8b has a cam piece fitting part 21b, and the divided mold 8b has a cam piece positioning plate part 21c and a bottle-shaped protrusion on the cam nose side. Cam piece engaging portion 21 consisting of
d, and a notch 21e for shaft penetration is formed in the plate-like portion 21C. Further, the other split molds 10a and 12a also have a cam piece fitting portion 22a and a journal piece fitting portion 23a, and the split mold 10
b and 12b also have a cam piece fitting part 22b and a journal piece fitting part 23b, and the split mold 10b
is provided with a cam piece positioning plate part 22c and a cam piece engaging part 22d consisting of a bottle-shaped convex part on the cam nose side, and a shaft penetrating notch 22e in the plate part 22c.
is formed.

Therefore, when the upper mold 1 and the lower mold 2 are clamped, the hollow cam pieces C, C2 are fitted between the divided molds 8a and 8b and between the divided molds 10a and 10b. A hollow portion for fitting the hollow journal piece Jt is formed between the split molds 12a and 12b, and a perfectly circular hollow portion for fitting the hollow journal piece Jt.

Further, each of the cam piece engaging portions 21d is provided on a part of the nose side of the hollow cam pieces C1 and C2.

A mold engaging portion 24.25 is provided which engages with 22d.

Next, the procedure for forming a bulge using the bulge mold shown in FIG. 1 will be explained using FIGS. 2, 3, 4, and 5.

When fixing the hollow shaft S, the hollow cam pieces C, C2, and the hollow journal piece J using the bulge mold shown in FIG. 1, first lower the upper mold 1 by raising the press upper ram 15. Keep it separate from mold 2.

Then, as shown in FIGS. 2(a) and 2(b), the split mold 8b that fits into the base side of the hollow cam piece C1 is raised by the plunger 18b, and the split mold 8b that fits into the nose side of the hollow cam piece C1 is raised. The mold 8a is lowered by the plunger 18a.

Next, as shown in FIGS. 3(a) and (b), the hollow cam piece C! is mounted on the split mold 8b from the left direction in FIG. 3(a), and the base side of the hollow cam piece C1 is placed on the cam piece fitting part 21b and brought into contact with the cam piece positioning plate part 21c. At the same time, hollow cam piece CI
By engaging the mold engaging part 24 provided in the mold with the cam piece engaging part 21d provided in the split mold 8b, the positioning of the hollow cam piece C1 and the positioning in the thrust direction are simultaneously performed. The cam piece C2 is similarly installed on the cam piece fitting part 22b of the split mold 10b, and the cam piece engaging part 22d and the mold engaging part 25 are engaged to simultaneously perform phase determination and positioning in the thrust direction. Furthermore, the hollow journal piece J is also fitted and installed on the journal piece fitting portion 23b of the split mold 12b.

Next, by lowering the press upper ram 15 and inserting and lowering the upper die 1, each plunger 18a is removed.

18b are pushed into the base plates 5 and 16, respectively, as shown in FIGS. ), and these split molds form a stem space in which the hollow shaft S can expand.

Next, the hollow cam pieces C, C2 and the hollow journal piece J have a hollow hole and a notch 21 for passing through the shaft.
e, fit the hollow shirt) S into 22e.

In this state, after both ends of the upper mold 1 and the lower mold 2 are closed with emboli 3a and 3b, a pressurized fluid, such as water, is fed into the hollow shirt S from the pressurized fluid inlet pipe 4, and the hollow shaft S By expanding the tube, the hollow cam pieces C, C2 and the hollow journal piece J are fixed to the hollow shaft S, as shown in FIGS. 1 and 5(a) and 5(b).

Subsequently, the upper press ram 15 is raised to lift the upper mold 1, and then the camshaft molded body is first shifted to the left in FIG. 5(a) to form the hollow cam piece CI + C2.
The mold engaging portions 24, 25 of the split molds 8b, 10b are separated from the cam piece engaging portions 21d, 22d of the split molds 8b, 10b, and then the camshaft molded body is shifted to the left in FIG. 5(b) and pulled out. Hollow camshaft 3 as shown in the figure
Get 0.

(Example) Examples will be described below.

First, Table 1 shows the materials of each part used.

Table 1 In addition, the mold engaging portion 24 of the hollow cam piece Cl + C2
．． 25 has a diameter d and a depth h as shown in FIG. 7(a).
and a long hole recess consisting of a semicircular portion at both ends having a diameter d, a length, and a depth h, as shown in FIG. 7(b). The concave portions were formed by compaction using an upper punch having a circular convex portion or an oval convex portion having the same shape as the mold engaging portions 24 and 25.

Next, the molding conditions and dimensional accuracy of the camshaft molded body in each example are shown in Table 2 together with comparative examples.
2) is used.

+ stripe・1, :ya"11-±" In Table 2, the thrust direction deviation and phase deviation of each cam piece indicate the maximum value of deviation from the dimension indicated in the drawing.

As shown in Table 2, the upper mold 101 has the tapered positioning receiving portions 101a and 102a shown in FIG.
In Comparative Example 1.2 in which the hollow cam pieces C, C2 were fixed by the lower mold 102, in Comparative Example 1, the hollow cam pieces CI
+ Due to poor dimensional accuracy in the thrust direction and phase of C2, polishing residue (black scale) may occur during cam polishing, resulting in product defects.In addition, as in Comparative Example 2, high bulge pressure When this happens, the hollow cam pieces C1*C2, which are not accurately held down by the tapered positioning receiving portions 101a and 102a, may break.

On the other hand, in the first to third embodiments of the present invention, in order to determine the phase of the hollow cam piece Cl + C2, the cam piece engaging portions 21d and 22d provided on the split molds 8b and 10b and the hollow cam piece C ,, by engaging the mold engaging portions 24 and 25 provided in C2, the hollow cam piece C1
+ Since the phase of C2 and the position in the thrust direction are accurately set, it is fixed by bulge forming.
It was possible to obtain a hollow camshaft molded body with high dimensional accuracy without cracking during bulge forming.

Also in Examples 4 to 6, the hollow cam piece C1+
Although it is possible to make the phase of C2 and the position in the thrust direction accurate, as a result of various experiments, as in Examples 4 to 6, it is possible to make the phase of C2 accurate and the position in the thrust direction. If the diameter of 24.25 is too large or too deep, the hollow cam piece C1+ C will be removed during bulge forming.
2 becomes easy to break, so it is not preferable, and conversely, the mold engagement part 24°25 provided on the hollow cam piece C1+C2
If the dimensions of hollow cam piece C1+ become too small,
This is not preferable as it will make it impossible to securely fix C2.
When the mold engaging portions 24.25 provided on the hollow cam pieces C and C2 have a circular shape as shown in FIG. 7(L), the diameter d is 2 mm or more and 10 mm or less, and the depth h is 1 mm or more. It is particularly preferable that the hole be made of a circular recess of 5 mm or less, and in the case of an elongated hole shape as shown in FIG. It is particularly preferable that the mold engaging portion 24.2 is formed of a long hole recess with a length of 5 mm or more and 15 mm or less and a depth h of 1 mm or more and 5 mm or less.
The diameter of the cam piece engaging portions 21d and 22d provided on the one-piece molds 8b and 10b corresponding to the shape of No. 5 is 2 mm or more and 10 m.
It has been found that it is particularly preferable to have a pin-shaped convex portion having a cylindrical shape of 1 mm or less and a height of 1 mm or more and 5 mm or less. When the 5 engaging portions 24 and 25 are elongated holes, the cam piece engaging portions 21d provided in the split molds 8b and 10b can be used even if there is some variation in the dimensions of the hollow cam piece sintered body.

22d can be smoothly engaged without any trouble.

In addition, in this invention, hollow cam pieces C, C2
The mold engaging portions 24 and 25 provided in the split molds 8b and 10b
The uneven relationship between the cam piece engaging portions 21d and 22d provided therein may be reversed.

[Effects of the Invention] As explained above, in the camshaft manufacturing method according to the present invention, when manufacturing a camshaft by fixing a predetermined number of hollow cam pieces and a hollow shaft by bulge forming, some of the hollow cam pieces are is provided with a mold engaging portion, and a cam piece engaging portion capable of engaging with the mold engaging portion is provided in a part of one of the split molds for bulge forming, and the hollow cam piece is re-engaged with the one split mold. The phasing and thrust direction positioning of the hollow cam piece is performed by fitting with the mating portions engaged, and then the hollow cam piece is moved between the hollow cam piece and the one split mold using the other split mold for bulge forming. Since bulge molding is performed with the hollow cam pieces fixed in place, there is no risk of cracks occurring in the hollow cam piece when the hollow cam piece is fixed to the mold, and the phase accuracy between each cam piece of the camshaft after bulge molding is In addition, the positional accuracy of the cam piece in the thrust direction is improved, and it is possible to manufacture a hollow camshaft of good quality, which is an extremely excellent effect.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an explanatory cross-sectional view of a bulge mold used in an embodiment of the present invention, FIGS. 2, 3, 4, and 5.
The figures are explanatory diagrams sequentially showing the process of bulge forming using the bulge molding die shown in Figure 1, in which (a) in each figure is an explanatory diagram in the axial direction, and (b) in each figure is an explanatory diagram in the direction perpendicular to the axis. Figure 6 is a partial perspective view showing an example of the shape of a hollow camshaft, and Figure 7 (a
)'(b) is an explanatory diagram showing an example of the shape of a mold engaging part provided in a hollow cam piece, and FIGS. 8(a) and 8(b) are explanatory diagrams of cross-sections in the direction perpendicular to each axis of the split mold in a conventional bulge mold. It is. DESCRIPTION OF SYMBOLS 1...Upper mold for bulge forming, 2...Lower mold for bulge forming, 6a-13a...Divided mold for upper mold, 6b-13b...
・Divided lower mold, 21C122C... Plate-like part for cam piece positioning, 21d, 22d... Cam piece engaging part, 24, 25... Mold engaging part, 30... Hollow camshaft, C ,, C2...Hollow cam piece, J...
Hollow journal piece, S...Hollow shaft. Patent applicant: Nissan Motor Co., Ltd.
Yutaka Oshio, Patent Attorney for Steel Tube Processing Co., Ltd. Figure 2 (a) (b) +8b Figure 3 1' 8b Figure 5 (G) Figure (b) 1b Procedural amendment December 24, 1985 Commissioner of the Patent Office Uga Michibe 1, Indication of the case 1985 Patent Application No. 234606 2, Name of the invention Method for manufacturing camshafts 3, Relationship with the person making the amendment Name of patent applicant (Name) (399) Nissan Motor Co., Ltd. Co., Ltd. name (
Name) W4 Tube Processing Co., Ltd. 4, Agent address (residence) Kobikikan Ginza Building, 2-8-9 Ginza, Chuo-ku, Tokyo 104 Telephone 03 (5B?) 2781 (
Representative) Electrician 03 (5B?) No. 7933 (Gm) 6, Number of inventions increased by amendment 7, Detailed description of invention in the specification subject to amendment. Figures 1, 2, 3, 4, and 5 of the drawings and line 20 of page 7 of the specification are corrected as follows. r12b, 13b, 30b, 31b,! = to a! has been done. 2. The 7th line of page 1O of the same is amended as follows. [〈. Further, the stem pressers 30b and 31b are also raised using a plunger. ] 3. The 7th line of page 12 is amended as follows. ``After lifting the stem holder 30b. 31b into the base plate 16, first place the camshaft molded body in the camshaft molded body.'' 4, Figures 1, 2, 3, 4, Figure 5 is corrected as shown in the attached sheet. Patent Attorney Yutaka Oshio Figure 2 (corrected figure) (a) (b) 8b Figure 3 (corrected figure) (0) (b) 8b Figure 5 (corrected figure) (b)

Claims (4)

[Claims] (1) When manufacturing a camshaft by fixing a predetermined number of hollow cam pieces and a hollow shaft by bulge forming,
A part of the hollow cam piece is provided with a mold engaging part, and a part of one of the split molds for bulge forming is provided with a cam piece engaging part that can engage with the mold engaging part, By fitting the cam piece in a state where both the engaging parts are engaged, the phase of the hollow cam piece and positioning in the thrust direction are determined, and then the hollow cam piece is divided into one part using the other split mold for bulge forming. A method for manufacturing a camshaft, which is characterized by bulge forming while being sandwiched and fixed between molds. (2) The mold engagement portion provided in a part of the hollow cam piece shall be a circular recess with a diameter of 2 mm or more and 10 mm or less and a depth of 1 mm or more and 5 mm or less on the surface of the hollow cam piece. A method for manufacturing a camshaft according to claim (1). (3) The mold engagement part provided in a part of the hollow cam piece has a shape on the surface of the hollow cam piece in the form of an elongated hole with semicircles with a diameter of 2 mm or more and 10 mm or less connected at both ends by a straight line. The method of manufacturing a camshaft according to claim (1), wherein the camshaft is formed of an elongated recess with a depth of 5 mm or more and 15 mm or less and a depth of 1 mm or more and 5 mm or less. (4) A patent claim characterized in that the cam piece engaging portion provided in a part of one of the split molds is a pin-shaped convex portion having a cylindrical shape with a diameter of 2 mm or more and 10 mm or less and a height of 1 mm or more and 5 mm or less. A method for manufacturing a camshaft according to item (1), item (2), or item (3).