JP2788179B2 - Electric corrosion prevention structure of hot forging die - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing electrolytic corrosion of a metal mold for hot forging for preventing each component of the metal mold from being electrolytically corroded by a potential difference generated during hot forging.

[0002]

2. Description of the Related Art Forgings such as crankshafts, which are automobile parts, generally have a lower mold (mold member) and an upper mold (mold) in a state where the material is heated to a considerably high temperature (not less than its recrystallization temperature). The member is pressed by a so-called hot forging method. In a mold used for this type of hot forging, an operation of applying a cooling water (cooling medium) or a release agent is usually performed in order to cool and lubricate a mold member.

[0003]

The above-mentioned cooling water and mold release agent tend to adhere to the gap formed on the mating surface of the die and the die set in the form of a film and remain. When there is a difference in the amount of charge due to charging due to vibration or friction, etc., a potential difference occurs in the mold, and electrical corrosion (hereinafter referred to as electrolytic corrosion) occurs in a portion where the mold configuration in the mold is dense. Will occur. Specifically, electrolytic erosion easily occurs on the mating surface of the lower and upper dies and the die plate holding them, the mating surface of the die plate and the base plate, and the mating surface of the base plate and the die set. For this reason, it is pointed out that irregularities due to electrolytic corrosion are formed on each of the mating surfaces, and the quality of the forged product is deteriorated, and the work of repairing the mating surfaces is frequently required, thereby reducing workability. ing.

The present invention has been made to solve this kind of problem, and it is possible to reliably and easily prevent electrolytic corrosion of a mating surface of a mold member and a die set with a simple structure, and to improve the forging quality and the work quality. It is an object of the present invention to provide a structure for preventing electrolytic corrosion of a hot forging die capable of improving the property.

[0005]

In order to achieve the above-mentioned object, the present invention provides forging a heated material through a mold member, while using a cooling medium and a lubricant. In hot forging dies that perform cooling and lubrication,
An electrolytic corrosion prevention structure for preventing the metal mold from being electrically corroded by a potential difference generated during the forging, wherein a plate portion holding the mold member and a die set portion contacting the plate portion are provided. A buried member embedded in one surface of the mating surface and in contact with the other surface of the mating surface, wherein the buried member has a lower specific resistance than each component of the mold and is electrically corroded. It is characterized by being formed of a material that is easy to handle.

[0006]

In the structure for preventing electrolytic corrosion of a hot forging die according to the present invention, the specific resistance is smaller and the electrode is easily corroded corresponding to the mating surface of the plate portion and the die set portion in the die. Since the embedded member is provided, when a potential difference occurs in the mold during forging, electrolytic corrosion concentrates on the embedded member. Therefore, electrolytic corrosion of each mating surface in the mold can be reliably prevented, and the durability of the mold is improved,
The quality of the forged product can be maintained effectively. Further, it is only necessary to replace the electrolytically buried member with a new buried member, thereby improving workability.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the structure for preventing electrolytic corrosion of a hot forging die according to the present invention will be described in relation to a die incorporating the same.
This will be described in detail below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 denotes a hot forging die into which the electrolytic corrosion preventing structure according to the present embodiment is incorporated. This mold 10 is provided with an arrow A according to a hot forging process.
A first mold member 12 for crushing, a second mold member 14 for rough molding, a third mold member 16 for finish molding,
A trimming member 18 is provided. These are a lower die set (die set part) 20 and an upper die set (die set part).
22.

The first mold member 12 includes a lower mold 24a and an upper mold 26.
a between the lower mold 24a and the upper mold 26a, a first cavity 28a corresponding to a crushing shape of a crankshaft W which is a forged product for crushing a material (not shown). It is formed. Second and third mold members 1
4, 16 are lower dies 24b, 24 like the first die member 12.
c and upper dies 26b and 26c. A second cavity 28b is formed between the lower mold 24b and the upper mold 26b according to the shape for rough molding of the crankshaft W, and is formed between the lower mold 24c and the upper mold 26c according to the shape for finish molding of the crankshaft W. A third cavity 28c is formed. The trimming mold member 18 includes a lower punch 30, an upper punch 32, a lower die 34, and an upper die 3 for trimming the crankshaft W.
6 is provided.

On the lower die set 20, a lower base plate (plate portion) 38 is provided. On the lower base plate 38, a first die plate 40, a second die plate 42, a third die plate 44, and a die plate Lower die plates 48 are sequentially arranged in the direction of arrow A via 46.

The first die plate 40 includes the first mold member 1.
2, and a plurality of knockout pins 52a fixed to a knockout bar 50a are disposed via a spring 54a so as to be able to advance and retreat with respect to the lower mold 24a. The second and third die plates 42, 44 have lower dies 24b, 24 constituting the second and third mold members 14, 16 similarly to the first die plate 40.
c is placed, and knockout pins 52b and 52c fixed to knockout bars 50b and 50c
The lower dies 24b and 24c are disposed so as to be able to advance and retreat through the lower dies 4b and 54c.

The upper die set 22 is provided with an upper base plate (plate portion) 56. The configuration on the upper base plate 56 side is the same as that on the lower base plate 38 side, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

In the mold 10 configured as described above,
Mating surface 5 of lower die set 20 and lower base plate 38
The electrolytic corrosion prevention structure 60 according to the present embodiment is incorporated into the mating surface 58b of the upper die set 22 and the upper die plate 22 with the upper die set 8a. The anti-corrosion structure 60 includes a plurality of embedded members 62 embedded in the surface 20 a on the lower die set 20 side and in contact with the surface 38 a on the lower base plate 38 side, and embedded in the surface 22 a on the upper die set 22 side and Base plate 5
A plurality of embedded members 64 that come into contact with the surface 56a on the sixth side.

The buried members 62 and 64 have a columnar shape, and have a mold 1 such as a lower die set 20, a lower base plate 38, an upper die set 22, and an upper base plate 56.
0 is formed of a material having a lower specific resistance than each of the constituent members 0 and easily corroded electrically. Specifically, lower die set 2
Since the lower base plate 38, the upper die set 22, the upper base plate 56, and the like are formed of an iron-based material, the embedded members 62 and 64 may be formed of zinc (Zn).

Therefore, when the crankshaft W is hot forged by the mold 10, first, a raw material (not shown) is placed in the first cavity 28a of the first mold member 12 while being heated to a predetermined temperature. The material is pressurized through the mold 24a and the upper mold 26a, and crushing is performed.

Next, the crushed molded product is gripped by a transporting means (not shown), transported in the direction of arrow A, and placed in the second cavity 28b of the second mold member 14. The crushed molded product in the second cavity 28b is subjected to rough molding under the pressing action of the lower mold 24b and the upper mold 26b, and then transferred to the third cavity 28c of the third mold member 16, where the lower mold 24c and the upper mold 24c are moved. Finish molding is performed via the mold 26c. Then, the finished molded product is carried into the trimming mold member 18,
A predetermined trimming process is performed to obtain a crankshaft W as a forged product.

During the above-mentioned hot forging operation, cooling water and lubrication are applied to the mating surfaces of the lower dies 24a to 24c and the upper dies 26a to 26c constituting the first to third mold members 12, 14 and 16. An agent is applied to cool and lubricate the mating surfaces. For this reason, in the gap between the mating surfaces, the cooling water and the lubricant remain as a thin film adhered, and are charged by vibration, friction, and the like accompanying the hot forging, and the lower dies 24a to 24c and the upper dies 24a to 24c are charged. A potential difference easily occurs between 26a to 26c. Accordingly, the parts having a dense mold structure, that is, the lower dies 24a to 24c and the upper dies 26a to 26c and the first to third die plates 40,
The respective mating surfaces P1 and P2 of the first and third die plates 40, 42 and 44, the lower base plate 38 and the upper base plate 56, respectively.
3, P4, knockout bar 50a and lower die set 2
0 and each mating surface P5, P6 of the upper die set 22,
Electrolytic corrosion is likely to occur on the mating surfaces 58a, 58b and the like.

However, in this embodiment, the mating surface 5
Embedding members 62 and 64 are embedded in the surfaces 20a and 22a of the lower die set 20 and the upper die set 22 corresponding to 8a and 58b. And these buried members 62 and 64
The first to third mold members 12, 14 and 16, the first to third die plates 40, 42 and 44, the knockout bar 50a, the lower base plate 38, the upper base plate 56, and the like have a higher specific resistance than each component of the mold 10. Is made of a material that is small and easily corroded electrically, for example, zinc.

Therefore, when a potential difference occurs in the mold 10, electrolytic corrosion concentrates on the embedded members 62 and 64, and the mating surface P1
In addition, an effect is obtained in which the occurrence of electrolytic corrosion on P6 and the mating surfaces 58a and 58b can be prevented as reliably and as possible. In particular, it is only necessary to embed the columnar buried members 62 and 64 on the surfaces 20a and 22a.
It is only necessary to replace the buried members 62 and 64 with new buried members after the electrolytic corrosion of 4, and there is an advantage that workability is improved.

In addition, since the mating surfaces P1 to P6 and the mating surfaces 58a and 58b are not formed with unevenness due to electrolytic corrosion, the durability of the mold 10 is improved at once, and the quality of the forged product is effectively improved. Can be maintained. Also,
Accordingly, there is also an effect that the manufacturing cost of a forged product is effectively reduced.

[0021]

According to the structure for preventing electrolytic corrosion of the hot forging die according to the present invention, the following effects and advantages can be obtained.

Since a buried member having a lower specific resistance and easily corroding electrically is provided corresponding to the mating surface of the plate portion and the die set portion in the mold, a potential difference is generated in the mold during forging. When this occurs, electrolytic corrosion concentrates on the buried member. Therefore, it is possible to reliably prevent the occurrence of electrolytic corrosion on each mating surface in the mold, improve the durability of the mold, and effectively maintain the quality of the forged product. Further, it is only necessary to replace the buried member that has undergone electrolytic corrosion with a new buried member, thereby improving workability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a hot forging die incorporating an electrolytic corrosion preventing structure according to an embodiment of the present invention.

[Explanation of symbols]

10 molds 12, 14, 1
6. Mold member 24a-24c ... Lower mold 26a-26c
... upper molds 28a to 28c ... cavities 38 ... lower base plates 40, 42, 44 ... die plates 56 ... upper base plates 58a, 58b ... mating surfaces 60 ... electrolytic corrosion prevention structures 62, 64 ... embedded members P1 to P6 ... mating surfaces W ... Crankshaft

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Ota 19 Matsuyama-cho, Moka-shi, Tochigi Honda Motor Co., Ltd. Tochigi Seisakusho (58) Field surveyed (Int.Cl. ⁶ , DB name) B21J 13/02

Claims (1)

(57) [Claims] 1. A hot forging die for performing forging on a heated material via a mold member and cooling and lubricating the mold member using a cooling medium and a lubricant, wherein the forging is performed during the forging. An electrolytic corrosion preventing structure for preventing the mold from being electrically corroded by a generated potential difference, wherein one of mating surfaces of a plate portion holding the mold member and a die set portion contacting the plate portion. And a buried member that is buried in the other surface of the mold and is in contact with the other surface of the mating surface. The buried member is made of a material having a lower specific resistance than each of the components of the mold and easily corroding electrically. An electrolytic corrosion preventing structure for a hot forging die, which is formed.