JPS63119944A - Forging method for piston - Google Patents

Abstract

PURPOSE:To improve the yield of a material, and to improve the production efficiency by forming a split structure consisting of plural members whose head parts are in a piston stock and projected in the diameter direction. CONSTITUTION:Side punches 8, 8 move to the inner part and brings a thick part of a stock to a plastic deformation, and the thick part is pressed against neck parts 10b, 11b of side members 10, 11 of the lower punch 9, and deformed. On the other hand, a metal of a forming part 8a portion which is invaded the thick part tries to flow to the upper part, as well, and since projecting parts 10a, 11a of the side members 10, 11 of the lower punch 9 of the inside face the upper part of the forming part 8b, said metal goes into the lower side there of, and covers the projecting parts 10a, 11a. On the other hand, end faces 8d, 8d of the forming part of the side punches 8, 8 are brought into contact with the outside peripheral surface of the thick part and press it, and control the flow to the outside in the diameter direction of the metal. In such a way, a piston pin boss part, and a recessed part are formed, and also, by the projecting part 10a, and undercut recessed part is formed in the upper part of the pin boss part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forging a piston used in an internal combustion engine.

(Prior Art) The piston of an internal combustion engine is as shown in FIGS.
2), a boss part (53) for attaching a piston pin that protrudes inward and is provided on opposing parts of the outer periphery of the skirt part, and a bottle hole (54) provided in the boss part;
The upper part of the bottle hole (54) is undercut to form a radial recess (55) for weight reduction.

When manufacturing the above piston, the undercut recess (55) described above can be easily formed by casting.
It is also easy to form the boss part for attaching the pin, but in the case of casting, there is a lot of machining required after finishing, and the piston is subjected to high pressure, making it difficult to control the blowhole and other parts during manufacturing. becomes.

Therefore, pistons are obtained by forging. In the case of forging, a disk-shaped billet is backwardly extruded to obtain a piston material, and the material is machined and finished to obtain a final product.

(Problems to be Solved by the Invention) The piston obtained by forging as described above has a densified structure and there are no problems such as cavities caused by casting, which improves the product's slight dripping. In addition, it is difficult to form the top shape such as the pulp escape at the top of the piston head, and it is difficult to form the undercut recess on the inner wall of the piston as described above. There are many parts, which is disadvantageous in terms of productivity, and excess meat, 41! As a result of the large number of machined parts, material dripping is reduced.

The present invention has been made to solve the above problems, and its purpose is to make it possible to form an undercut recess by forging when forming a piston by forging.
To provide a piston forging method that improves external shape and dimensional accuracy, minimizes machining to improve production efficiency, and improves material dripping, which is advantageous in terms of cost.

(Means for solving the problem) The method for solving the above problem is to hold a piston material formed into an inverted cup shape by surrounding it with a die, set it between upper and lower punches, and then press the material with the upper punch. The material is restrained from above, a lower punch is fitted from below to support the material, and a recess for a piston pin boss is formed on the outer periphery of the material by a side punch from the side. It has a split structure consisting of a plurality of members protruding in the radial direction, and when the side punch is used to form the recess for the piston pin post, the lower punch head simultaneously forms an undercut recess in the radial direction on the inner wall of the material above the boss. After molding, the upper punch and side punch are released, and then the restraint of the dividing member of the lower punch is released, and the punch is retracted and closed to take out the molded product.

(Effects of the above means) According to the above means, an undercut recess can be formed on the inner wall of the piston material at the same time when the piston pin post part is formed on the outer periphery of the piston material, and the head of the piston material can be restrained from above to reduce the pressure. By setting this, the piston top can be formed at the same time.

(Embodiment) Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figures 1 to 3 show the piston forging process in the order of raw material, molding material, and molded product.
The cross-sections are taken by changing the angle.

FIG. 1 shows a thick disk-shaped material (A) called a billet, and the material is, for example, an aluminum alloy JIS 2018 material. Instead of this, 0 or more materials (such as sintered metal) may be used (
A) is pre-molded to obtain a molding material (B) as shown in Fig. 2,
The molded material (B) has an inverted cup shape and has a head (B1), an axially long skirt part (B2), and an axially short thick part (B3).
) and (B3) are provided at opposing positions on the skirt portion. This forming material (B) is formed by forging as shown in Fig. 3,
A molded product (C) is obtained, and the molded product (C) includes a head (C+), a molded skirt part (C2), and the thick wall part (B3) described above.
A piston pin post part (CC4) with a radially recessed part (C3) that protrudes inwardly is molded into a piston pin post part (CC4), which has a radially outward concave part (C3) formed in the radially outward part of the peripheral lower part of the head (Cθ) above the protrusion of the boss part (C4). It has an undercut recess (C6) and a boss part (C4).
) The wall (Cs) of the recess (C3) is thinned, and this portion is bored to form a piston pin hole.

Figures 4 to 10 show a specific example of piston forging along with the operation of the device.
2), middle gui under this (3), lower gui under this (4)
A base (16) is arranged under the lower guide (4), and the piston molding material (B) preformed from the billet (A) described above is tightly packed on the upper guide (2). Fitting hole (
2a). The middle gouge (3) is provided with a sliding hole (3a) concentric with the hole (2a), and the middle or lower part of the hole (3a) is formed with a concave part (3b) that widens toward the end. A large diameter space (4a) is provided so as to penetrate vertically.

An upper punch (5) that slidably fits into the hole (2a) of the upper die (2) is provided above the upper die (2), and the upper punch (5) connects the upper base (5a) to the lifting frame (6). It is held hanging down through a holder (6a), and cams (
7), (7) are installed hanging down. In the lower part of the upper guide (2), horizontal guide holes (2b), (2b) are formed 180° apart so as to sandwich the lower part of the hole (2a).
Side punches (8), (8) are fitted into this so as to be able to slide freely in the horizontal direction, and the opposing tips of the side punches (8), (8) have molding for forming a small diameter piston pin boss part. (8a) and (8a) are formed, and a guide hole (2b) is formed.
), (2b), the side punches (8
) and (8) have cam portions (sb) that engage with the cams (7) and (7).

(8b) is provided.

The lower punch (8) is provided so as to face the upper punch (5), and the upper molded part (9a) is pressed against the upper punch (9a) at the forging set position.
2) facing the middle or lower part of the hole (2a), and the middle part (9b
) is slidably fitted into the hole (3b) of the intermediate gouer (3), and the punch (9) is the left and right side member (10).

(11), the middle member (12) consists of three divided members, and the upper parts of the side members (10), (11) have protrusions (10a), (lla) that bulge symmetrically outward. , this lower neck (10b), (llb), neck (10b), (
llb) below each outwardly slanted base (10c
), (lie), and the neck portions (10b), (llb) are formed with side punches (8), (8) forming portions (8a), (8).
Corresponding to a), the opposing inner surfaces of the side members (10) and (11) are flat, and the upper part (12a) of the intermediate member (12) is sandwiched between them, and the top part (12b) of this is flat. 10), top of (11) (10a), (lid)
and form a connecting surface.

Bases (10c), (ll) of side members (10), (11)
c) At the proximal end, there is a horizontal lower end receiving surface of the molded material (
10e).

(lie) is formed, and the arm parts (lof) and (llf) are suspended from this so that the upper part touches the inner periphery of the hole (3a), and the inside of the arm parts (10f) and (llF) has a recess from the middle part downward. (10g) and (11g) are formed, and the lower part (10h) and (llb) of the arm part are bent so as to expand outward symmetrically, while the intermediate member (
12), the intermediate part (12c) is the arm part (10F), (l
tr) so that both sides touch the middle part of the lower part (12
d) is an enlarged view of the lower part (10h).

(llb), and the intermediate member (12) is fixed to the base (
1B) erected on top. Lower part of the arm (loh), (l
lb) Recesses (10i) and (lli) are provided at the lower end, and cylinders (1
3) Engage the upper ends of the rods (13a) and (14a) of (14) to remove the rod (13a).

The upper end of (14a) is a bottle (13b), (14b) and a recess (10i).

Long holes (10j) and (llj) formed in the vertical wall of (lli)
).

In the above process, the forming material (B) is introduced from above the hole (2a) of the upper guide (2), and the material (B) is placed in the lower punch (
8), the receiving surfaces (10e) of the left and right side members (10), (11)
).

(lie) with its lower end supported on the upper part of the punch (9a
) is loosely fitted within the inner diameter of the material (B) to support the head (B) from below, and the molded part (9a) of the lower punch (9) is integrated, such a set state is shown in Figure 4. Ta.

Next, lower the upper punch (5) by lowering the lifting frame (8),
The upper punch (5) fits into the hole (2a) of the upper gouge (2) and presses and presses the head (Bl) of the molding material (B) from above. The movement also lowers the cams (7), (7), and the slopes (7a) of these cams (7), (7a) strike the side punches (8), (
As a result, the side punches (8), (8) move symmetrically inward, and the forming part (8a) of the opposing tip part engages with the slope (8c) of the cam part (8b) of the side punch (8). ),
(8a) intrudes radially inward from the outer periphery of the forming material (B), plastically deforms the thick part (B3) and deforms it inward, and the thick part (B3) is inserted into the lower punch (8). side member (10),
The neck (tab) and (ttb) of (11) are pressed and deformed, and on the other hand, the meat of the molded part (8a) that has entered the thick part (B3) tries to flow upward as well, and the molded part (8a) at the forward limit ( 8b)
Side members (10), (11) of the lower punch (8) inside the upper part
), the protrusions (10a) and (lla) are facing you, so enter the lower side of the protrusions (10a).

Wrap (llb) and on the other hand, side punch (8), (8)
The end faces (8d) and (8d) of the proximal end of the molding part (8a) are the thick part (B2) of the material (B) at the intrusion molding limit of the molding part (8a).
) and pressurizes it to restrict the radially outward flow of meat. This allows the piston pin position part (C4
), the concave part (C3) is formed by the molding part, and the protrusion part (1
0a).

In (1a), an undercut recess (C6) is formed above the bin post part (C4). This is shown in Figure 6.

After forming, the upper punch (5) is raised, and at the same time the side punches (8), (8) are moved back, and the punches (5), (8)
.

To release the molded product (G) from the constraint of (8), drive the cylinders (13) and (14) and rods (13a) and
14a), and the side members (10) and (11) of the lower punch (9) that are connected thereto are moved upward, and the lower part (10h) of one arm part (10f) is moved up on this side of the recessed part (3b). On the other hand, the intermediate member (12) is fixed in place by sliding from the inside of the upper part of the side members (10) and (11) with the upward movement of the punch. Facing the recesses (10g) and (ltg), it comes off in this state, and the side member (10) approaches the opposite side member (11) due to the guiding action of the slope (3C), and finally the upper inner surface (10k)
, (llk) are in contact. The movement of the side member (10) to the right in the drawing is made without any problem because the rod (13) engages with the bottle (13b) due to the elongated hole (10j), and the member (lO
) is brought into contact with the member (11), and the protrusion (10a) is extracted from one of the undercut recesses (C6) of the molded product (C). This is shown in FIG.

Next, only the upward movement of the rod (14a) of the cylinder (14) is performed, and as a result, the right side member (11) is moved to the lower part of the arm part (11) since the slope (3d) on this side is far outward in the radial direction.
llb) rises until it comes into contact with this, while the left side member (lO) remains with the slope (3C) as its upper limit of movement, and the molded product CG) also rises at the upper limit of member (11), and the member (10)
Since the protrusion (10a) on the top of
1), and the protrusion (10) of the member (10) rises from the molded product.
10a) is extracted. This is shown in FIG.

As the member (11) continues to rise further, the member (11) moves inward due to the action of the slope (3d).Meanwhile, the molded product is held by the clamp (15), whereby the member (11)
The protrusion (lla) of the member (10
) is lowered and returned to the molding position, as shown in FIG. 10, and then the member (11) is lowered and returned to the molding position to complete dispensing of the molded product.

Through the above process, a molded product as shown in FIG. 3 was obtained.

In this way, the bottle boss portion and the undercut recess are simultaneously forged into the member (B), and the molded product is discharged.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to forge the undercut portion at the same time as forming the piston bottle boss portion and its concave portion, thereby eliminating the need for machining the undercut portion. In addition to minimizing machining and improving production efficiency, this also reduces material dripping, which is advantageous in terms of cost.Also, since it is forged, dimensional accuracy improves, contributing to the reduction of machining. This method has many advantages, such as the ability to mold the top of the piston head at the same time by applying pressure to the head of the material.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIGS.
The figures show the molding process. Figure 1 is a diagram of the raw material, Figure 2 is a cross-sectional view of the preformed material, Figure 3 is a cross-sectional view of the molded product, and Figure 4 is a cross-sectional view of the molded product.
The figure is a longitudinal cross-sectional view of the forming device, showing the state of the preforming material set, Fig. 5 is a plan view of the lower punch, Fig. 6 is a sectional view of the forming state, and Fig. 7 is the relationship between the lower punch and side punch. FIGS. 8 to 10 are cross-sectional views showing the molded product discharging process in order, FIG. 11 is a cross-sectional view of the piston, and FIG. 12 is a bottom view of the piston. In the drawings, (B) is the piston material, (C) is the molded product, and (C) is the piston material.
3) is the concave part for the bin, (C4) is the boss part, (2)
Hagui, (5) is an upper punch, (8) is a side punch, (
8) is a lower punch, and (10), (11), and (12) are lower punch dividing members. Patent applicant: Agent for Honda Motor Co., Ltd.
Patent Attorney Part 2 1) Yong-Immediate Question Patent Attorney
Kuni Ohashi, Patent Attorney, Department
Udo Yama Patent Attorney No 1)
Shigeru Figure 5 Figure 7

Claims (1)

[Claims] The piston material formed into an inverted cup shape is surrounded and held by a die and set between the upper and lower punches, and the upper punch restrains the material from above, the lower punch fits and supports the material from below, and the side The step of forming a concave portion for the piston pin boss portion on the outer periphery of the material using a side punch from the side, and the lower punch has a divided structure consisting of a plurality of members whose heads are inside the piston material and protrude in the radial direction, and the side punch When forming the recess for the piston pin boss part, the lower punch head simultaneously forms an undercut recess in the radial direction on the inner wall of the material above the boss part, and after forming, the upper punch and the side punch are released, and then the lower punch A method for forging a piston, comprising the steps of releasing the restraint of the divided members and retracting and closing the punch to take out the molded product.