JPH02104438A - Die assembly for forming valve spring retainer - Google Patents

Abstract

PURPOSE:To reduce the manufacturing cost without reducing the rigidity of a retainer by arranging the outer edge of the center hole of an upper die through which a punch forming the center tapered hole of the retainer comes and goes on the end face which is the thickest in the axial direction. CONSTITUTION:The base material of Al alloy worked circularly undergoes compacting by both upper and lower dies 41, 42 of a die assembly 40 into an intermediate body 43. This intermediate body 43 is mounted on a lower die 31, compressed and held between this lower die and an upper die 33 and pressed by a punch 35 from the upper part to forge the retainer 15. In this time, the outer edge 36 of the center hole 32 of the upper die 33 takes the thickest position in the axial direction of the retainer 15 in the upper end face 23a of the retainer 15, for example, the rigidity is improved compared with the case when the outer edge is arranged on the upper part of a comparatively thin-wall annular shoulder face 21. Then, the unnecessary part pushed into the center hole 32 of the lower die 31 is cut out of an edge part 26 of the retainer 15, the edge part 26 is rounded and burrs are removed from parts facing the outer edge 36 to complete a valve spring retainer 15.

Description

Detailed Description of the Invention [Object of the Invention] <Industrial Application Field> The present invention relates to a mold for forming a valve spring retainer for holding a valve spring wound around each valve stem of an intake and exhaust valve of an engine. The present invention relates to an apparatus, and particularly to a mold apparatus for forming a valve spring retainer made of an aluminum alloy.

Prior Art> Valve spring retainers used in engine intake and exhaust valves are generally made of steel, but since the retainer reciprocates with the valve, it is preferable to make it as light as possible. It has been proposed to use a strong aluminum alloy.

In order to form the above-mentioned aluminum alloy into a valve spring retainer, the aluminum alloy is first processed into a cylindrical shape by extrusion molding, which is then cut into a disk shape and then formed into the shape of the retainer by forging.

However, in particular, the center hole into which the retainer is inserted has a tapered shape, and when forming such a tapered hole, the mold is likely to wear out, so it is preferable to use cemented carbide. If a cemented carbide material is used for the entire mold on the forming side, the cost tends to rise. Furthermore, if the retainer is forged at once using a pair of upper and lower dies, there is also the problem that centering becomes difficult. Therefore, the above problem can be solved by sliding the bonder for forming the tapered hole into the center hole of the upper mold for forming other parts. However, if the outer edge (parting line) of the center hole is placed, for example, in a thin part of the outer periphery of the retainer, there is a problem that stress is concentrated in that part and the strength of the retainer is reduced. Furthermore, if the outer edge of the center hole is located at the edge of the end face and the tapered hole, any dents remaining on this portion of the retainer will become an obstacle when automatically assembling the cotter.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main object of the present invention is to reduce manufacturing costs without reducing the rigidity of an aluminum alloy valve spring retainer, and to provide a 1q valve. An object of the present invention is to provide a mold device for forming a spring retainer.

[Structure of the Invention] <Means for Solving the Problem> According to the present invention, a concentric annular shoulder for holding a valve spring wound around a valve stem of an intake and exhaust valve of an engine is provided. A mold device for forming a valve spring retainer made of an aluminum alloy having a surface on one end surface, the lower mold having a mold surface corresponding to one end surface of the retainer and a concentric center hole, and the other end surface of the retainer. an upper mold having a concentric center hole corresponding to the outer peripheral edge of the mold; and an upper mold having a concentric center hole corresponding to the outer peripheral edge of the mold, and slidingly engaged with the center hole of the -F mold to form at least a large part of the tapered hole in the center of the base material held between the two molds. The retainer has a punch that is harder than both of the molds and whose diameter gradually decreases toward the tip, and the outer edge of the center hole of the upper mold is located at the thickest position in the axial direction of the retainer. This is achieved by providing a mold apparatus for forming a valve spring retainer.

<Function> In this way, the punch made of a relatively expensive cemented carbide material can be made as small as possible, and the outer edge of the center hole of the upper die is located at the thickest part of the retainer. Therefore, the rigidity of the retainer does not decrease after manufacturing.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The internal combustion engine main body (not shown) is provided with a pair of intake valves 1.2, as shown in FIGS. 1 and 2.

Both intake pulps 1.2 are connected to the crankshaft (not shown)
A pair of low-speed cams 4.6 and a single high-speed cam 5, each having a roughly egg-shaped cross section, are integrally installed on the camshaft 3, which is driven synchronously at a speed of 1/2 of the speed of the camshaft 3. ~6
The first to third transmitting members engage with each other to perform rocking motion.
The opening/closing operation is performed by working with the zero tension arms 7 to 9. Additionally, this internal combustion engine is equipped with a pair of exhaust valves (not shown), which are driven to open and close in substantially the same configuration as the above-mentioned intake valve 1.2, but below, only the intake valve side will be described. explain.

The first to thirtieth lever arms 7 to 9 are connected to a rocker shaft 10 fixedly installed below the camshaft 3 in parallel with the shaft.
are pivotally supported adjacent to each other so as to be able to swing freely. Of these, the first and thirtieth lever arms 7.9 have basically the same shape, their bases are pivotally supported by the rocker shaft 10, and their free ends extend above both intake valves 1.2. It's out. Tappet screws abutting the upper ends of the respective intake valves 1.2 are screwed into the free ends of the double-ended hook arms 7.9 so as to be movable forward and backward, and are prevented from loosening by lock nuts.

The 20th claw arm 8 is connected to the first and 30th claw arms 7.
It is pivotally supported by a rocker shaft 10 between 9 and 9. This second
The zero tension arm 8 slightly extends from the rocker shaft 10 toward the middle of both intake valves 1.2, and the upper end surface of a lifter (not shown) comes into contact with the cam slipper 8a on the upper surface of the 20th tension arm 8. 5 always [1i+ffl
The rocker arm is elastically biased so as to come into contact with each other.

As described above, the camshaft 3 is rotatably supported above the engine body, and the low-speed cam 4.6 and the high-speed cam 5 are integrally connected. Low speed cam 4.6
is formed in a cam profile suitable for the low speed rotation range of the engine, and its outer peripheral surface is in sliding contact with the cam slippers 7a and 9a formed on the upper surface of the first and 30th lever arms 7.9, respectively. It is being done. In addition, the high-speed cam 5 is
The cam profile is designed to match the engine's high-speed rotation range.

Each of the rocker arms 7 to 9 has a connecting device 14 installed in a hole drilled through the center thereof and parallel to the rocker shaft 10, so that the rocker arms 7 to 9 can be in a state where they can swing integrally and a state where they can be relatively displaced. and can be selectively switched.

On the other hand, each valve stem 1a, 2a of each intake valve 1.2
A valve spring retainer 15.16 is provided at the l end via a retainer, and at the same time, between these retainers 15.16 and the engine body, each valve stem 1a
, 2a, each pair of valve springs 17.1
8 is wrapped around each intake valve 1.2.
is always resiliently biased in the valve closing direction, that is, upward in FIG.

Here, the valve spring retainer 15.16 is made of 14.5 wt% silicon, 2°2 wt% copper,
3. Hard particles made by producing atomized powder containing 0.7 wt% magnesium, 4.2 wt% iron, and 2.1 wt% manganese, and mixing alumina, silica, and titanium oxide with this.
0 wt% was added, the powder was compacted, and the product was sintered into a columnar shape by hot extrusion, cut into a disk shape, and then formed by @-shaping as described later.

Since both valve spring retainers 15, 16 have similar structures, only one of the valve spring retainers 15 will be described below with reference to FIGS. 3 and 4. This retainer 1
No. 5 has a tapered hole 20 through which the valve stem 1a passes through the valve stem (taper angle 20°). Further, an outer valve spring 1 is provided on the outer peripheral surface of the retainer 15.
It has a first annular shoulder surface 21 as a spring seat for holding the valve spring 7 and a second annular shoulder surface 22 as a spring seat for holding the inner valve spring 18.

Here, the axial length L2 from the lower end surface 23a to the second annular shoulder surface 22 near the free end of the valve stem 1a in the retainer 15, that is, shown in FIG. The axial length up to [is longer than half of 1. Further, the axial length L3 from the first annular shoulder surface 21 to the second annular shoulder surface 22 is the upper end surface 23a.
It is longer than the axial length L4 from the to the first annular shoulder surface 22 and the distance L5 from the second annular shoulder surface 22 to the lower end surface 23b. In this example, Ll is 8.88.
L2 is 6.0mtn, L3 is 3.8 closed, L4 is 2.2#
, L5 is 2.8M, and the outer diameter of the lower end surface 23a is 28.0m.
m, the outer diameter of the lower end surface 23b is 15.4 m, and the outer diameter of the second annular shoulder surface 23 is 21.7 m.

On the other hand, the outer circumferential surface portions 24.25 adjacent to and facing each annular shoulder surface 21.22 are each tapered in diameter from the upper end surface 23a toward the lower end surface 23b along the axial direction. (each taper angle is 5°). Therefore, not only the continuity of the internal crystal is improved compared to the case where each outer circumferential surface is orthogonal to each annular shoulder surface, but also the lubricating oil flying from the free end side of the valve stem 1a is easily sprayed. This also has the effect of suppressing thermal deformation of the retainer 15.

Furthermore, each valve spring 17.18 has an outer peripheral surface portion 24.
25 can also be prevented.

On the other hand, as shown in FIG. 4, which shows a further enlarged view of the retainer 15, the lower end surface 23 of the tapered hole 20 of the retainer 15
The b-side edge 26 is machined to have a continuous rounded short hanging part (curvature radius 1.5 m>
. Therefore, unlike the case where the edge is simply chamfered, the edge 2
No burrs remain or corners are formed on 6, causing stress concentration. Note that the outer and inner edges of the upper end surface 23a of the retainer 15 are rounded to improve the ease of loading the cock.

Below, the manufacturing procedure of the retainer 15 will be explained in detail with reference to FIGS. 5 to 7.

As shown in FIG. 6, the retainer forming mold device 30 has mold surfaces corresponding to both annular shoulder surfaces 21, 22 and the lower end surface 23b of the retainer 15, and has a central hole 32 as a dust hole in the lower center. 5KD61 (JIS standard)
an upper mold 33 made of 5KD61 having a surface corresponding to most of the outer peripheral edge of the upper end surface 23a; the upper mold 33 slides into and out of the center hole 34 of the upper mold 33; The punch 35 is made of a cemented carbide material harder than 5KD61 and has a mold surface corresponding to the outer periphery of the tapered hole 20 on the end surface 23a and the tapered hole 20.

- In order to actually form the retainer 15, first, as shown in FIG. The intermediate body 43 is compression molded.

Then, this intermediate body 713 is placed on the lower mold 31, compressed and clamped between it and the upper mold 33, and pressed with the punch 35 from above as shown in FIG. 6 to form the shape shown in FIG. Forged into. At this time, the outer edge 36 of the center hole 32 of the upper die 33
By setting the thickness to the thickest position in the axial direction of the retainer 15 on the upper end surface 23a of the retainer 15, its rigidity can be improved compared to, for example, the case where the outer edge is disposed on the upper part of the relatively thin annular shoulder surface 21. will improve.

Next, as shown in FIG. 7, the lower mold 31 is
The unnecessary portion pushed into the center hole 32 of the retainer 15 is removed using a cylindrical punch 37 made of a member different from the punch 35.
Cut it off from the edge 26 of.

In this manner, the retainer 15 is completed by rounding the edge 26 of the forged retainer 15 and removing the ridges corresponding to the outer edge 36.

[Effects of the Invention] As described above, according to the present invention, the outer edge of the center hole of the upper mold, in which the punch forming the center taper hole of the valve spring retainer is retracted, is placed on the end face of the thickest part in the axial direction of the retainer. By arranging the punch for forming the tapered hole portion, the punch for forming the tapered hole portion using a relatively expensive cemented carbide material can be made as small as possible without reducing the rigidity of the retainer, and the cost can be reduced. From the above, the effects of the present invention are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing a valve operating mechanism of an automobile engine in which a valve spring retainer formed by a molding device according to the present invention is used. FIG. 2 is a side view showing the valve mechanism with a portion cut away, similar to FIG. 1. FIG. 3 is a longitudinal sectional view showing only the valve spring retainer. FIG. 4 is an enlarged view of the main part of FIG. 3. FIG. 5 shows a die device for forging an intermediate body of a pulp spring retainer. 6 and 7 show a mold apparatus for forming a valve spring retainer according to the present invention. 1.2...Intake valve 1a, 2a...Valve stem 3...Camshaft 4.6...Low speed cam 5
...High-speed cam 7...10th lever arm 8.
...20th Tsuka Arm 9...30th Tsuka Arm 7a,
8a, 9a...Cam slipper 10...Rocker shaft 11...Cylinder head 1
4... Connecting device 15.16... Retainer 17
．． 18... Valve spring 20... Tapered hole 21.22... Annular shoulder surface 2
3a, 23b... End surface 24.25... Outer peripheral surface portion 26
... Edge 30 ... Retainer forming mold device 31 ... Lower mold 32 ... Center hole 33 ...
Upper die 34...center hole 35...punch
36... Outer edge 37... Punch 40...
・Mold device 41... Upper mold 42... Lower mold 43
... Intermediate patent applicant Honda Motor Co., Ltd. representative
Patent Attorney Yo Oshima Figure 1 Figure 2

Claims (1)

[Scope of Claim] A mold device for forming a valve spring retainer made of an aluminum alloy and having a concentric annular shoulder surface on one end surface for holding a valve spring wound around a valve stem of an intake and exhaust valve of an engine. a lower mold having a mold surface corresponding to one end surface of the retainer and a concentric center hole; an upper mold having a concentric center hole corresponding to the outer peripheral edge of the other end surface of the retainer; and both molds. a punch that is harder than both of the molds and that slides into the center hole of the upper mold and gradually reduces in diameter toward the tip in order to form at least most of the tapered hole in the center of the base material held between the punches; A mold device for forming a valve spring retainer, characterized in that the outer edge of the center hole of the upper mold is located at the position where the retainer is thickest in the axial direction.