JPH07121425B2 - Punching tool - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a punching tool such as a punch or a die used for punching a thin metal plate such as steel or copper alloy.

[Conventional technology]

At present, cemented carbide is mainly used as a high-grade punching tool for thin metal plates. Cemented carbide has a hardness
As a tool material for punching, which has high strength and toughness,
Although excellent, in the case of non-lubrication, WC particles are chipped off, wear due to seizure and peeling of the work material is severe, and the life is remarkably shortened, so a lubricant (oil) is used, but it adheres to the work material Since it is necessary to wash the lubricant, CFCs and chlorine-based organic solvents are required, which poses a problem of causing pollution.

In order to solve these problems, studies using ceramics have recently been advanced, and some experimental results have been reported although they are still in the research stage. In particular, it has been reported that among the ceramics, ZrO ₂ series ceramics, which have excellent fracture resistance, have excellent durability in punching and may be put to practical use (for example, the 36th plastic working Joint Lecture '85 -10-6-8 Trial use of zirconia tools).

Further, as a punching tool, in Japanese Patent Laid-Open No. 63-20132,
It is described that the zirconia sintered body can be used for punches or dies for bending, punching and the like.

[Problems to be Solved by the Invention]

Generally, when punching a lead frame, etc., it is about φ0.3 for round punch and 0.3w for square punch.
It is required to use a punch having a small diameter (width) or a thin punch. However, since ceramics have lower toughness as compared with cemented carbide and steel, there is a problem in that when they are used in punches having a small diameter or a thin wall, breakage occurs at the initial stage and they cannot be put into practical use.

An object of the present invention is to provide a punching tool that can be used without breaking even a punch having a small diameter or a thin wall and has a longer life than a currently used cemented carbide.

[Means for Solving the Problems]

The present invention is a tetragonal ZrO ₂ : 60 compounded with Y ₂ O ₃ and Nd ₂ O _3.
〜80vol% and Al ₂ O ₃ : 20〜40vol%, HIP-sintered ZrO ₂ series ceramics with bending strength: 120Kg / m
m ² or more, fracture toughness: 7.5 MN / m ^1.5 or more, Vickers hardness: 13
A punching tool is characterized in that a cutting edge portion made of ceramics having a characteristic of 00 or more is joined to a base material made of steel or cemented carbide.

In the present invention, when toughness and cost are important, it is advantageous to use steel as the base material, but when importance is attached to the wear resistance of the side surface of the punch or die, cemented carbide is used as the base material. It is preferable to use.

The thickness of the ceramics to be joined is preferably as thin as possible in order to prevent breakage, and 0.2 to 5 mm is suitable.

In addition, the mechanical properties required for ceramics for the cutting edge are three factors, strength, toughness, and hardness. If strength and toughness are low, the possibility of chipping increases, so the bending strength: 120 kg / mm ² or more, the fracture toughness: it is necessary 5.5MN / m ^1.5 or more materials. Hardness is an important factor for improving wear resistance, and Vickers hardness of 1300 or more is desirable in order to obtain a tool life that is at least twice as long as that of cemented carbide that is currently used. In particular, tetragonal ZrO ₂ : 60-80 vol% and Al ₂ O ₃ : 20
ZrO ₂ based ceramics, which consist of ˜40 vol% and are densely sintered by HIP, satisfy these conditions and are the most preferable materials. For ZrO _2, it is necessary to add carbides and oxides individually or in combination to improve the sinterability, but it is optimal to add Y ₂ O ₃ and Nd ₂ O ₃ in combination. In the case of processing a punch or die having a complicated cross section, it is easier to cut out by wire cutting from a metal block to which a ceramic sheet is joined. It is necessary to have an electrical resistivity of × 10 ^-2 Ω · cm or less. Specifically, the tetragonal type
By adding a nitride or a carbide to ZrO ₂ , it is possible to impart conductivity and enable wire cutting.

〔Example〕

The punching punches of various zirconia-based ceramics and cemented carbide were made, and the durability was evaluated by changing the punch shape, the work material and the lubrication method. Ceramics 1 is 5 × 30
A material of × 1 ^t (mm) was manufactured or purchased and joined with the hot die steel SKD61 {5 × 30 × 60 ^t (mm)} which is the base material 2. The joining was performed by the following method.

After forming a composite plating layer of about 20μ consisting of Ni and Ti components on the ceramic joint surface 5 x 30 (mm), 900 ℃, 1
Heat treatment was performed in a reduced pressure atmosphere of 5 × 10 ⁻⁴ torr for 0 minutes to diffuse Ti into ceramics to form a strong film. Next, Ni plating is applied to the joining surface 5 × 30 (mm) of hot die steel SKD61 to about 5 μm.
After the formation, Ag brazing was placed between the ceramics on which the plated layer was formed, and hot pressing was performed in vacuum at a temperature of about 700 ° C. for complete bonding.

The shape of the material after joining is shown in FIG.

Table 1 shows the composition and mechanical properties of various materials used as the cutting edges. The flexural strength, fracture toughness, and hardness were measured by the following methods.

The bending strength was measured according to JIS R1601. The fracture toughness value was calculated using the following Nihara's formula by the Vickers indentation method.

K ₁ c: Fracture toughness value, a: 1/2 of indentation length, P: Load (30Kgf),
E: Young's modulus, C: 1/2 of crack length Further, the hardness was measured by a Vickers hardness meter at a load of 500 g.

The materials shown in FIG. 1 in which the ceramics A to D shown in Table 1 were joined were machined into punching punches having the shapes shown in FIGS. 2 and 3. As a conventional example, punches of the same shape were obtained from the cemented carbide of D shown in Table 1. The thickness of each ceramic from the joint is 0.5 mm.

A punching processing test was performed using the punching punch thus prepared. The die at this time was made of cemented carbide and was used by exchanging it every 500,000 shots. Table 2 shows the tip shape of the punch used in the test and the test conditions. The conditions 1 and 2 shown in Table 2 correspond to the rectangular shape shown in FIG. 3, and the condition 3 corresponds to the round punching punch shown in FIG. 2, respectively.

As the evaluation method, after 200,000 shots, the flash height of the cut portion of each of the workpieces was measured, and when the flash became 50 μm or more, the total number of shots was obtained as the tool life.

The results are shown in Table 3. From Table 3, the punch of the present invention using the ceramic made of ZrO ₂ to Y ₂ O ₃ and Nd ₂ O ₃ ZrO ₂ tetragonal complexed added and for Al ₂ O ₃ punching tool (material A) Turns out to be particularly good. Furthermore, the punches made of materials B and C that do not contain Al ₂ O ₃ did not have much improved life, and had a shorter life than the conventional cemented carbide. In the case of cemented carbide, both the bending strength and the fracture toughness value are higher than those of ceramics, but peeling occurs due to seizure with the work material, and durability is particularly problematic without lubrication. It is also found that the use of the lubricant is superior to the cemented carbide.

Ceramic-integrated punches were also manufactured from the material A shown in Table 1 and tested under the conditions Nos. 2 and 3 shown in Table 2, but they were all unfavorable because they were broken at the initial stage.

[Effects of the Invention] According to the present invention, a sufficient life can be obtained even in the use without lubrication, which was difficult with the conventional cemented carbide punching tool.
Further, it is possible to provide a punching tool applicable to a punching die having a small diameter or a thin wall, which is a problem of the ceramic punching tool currently being researched.

Moreover, since it can be used without lubrication, it does not require cleaning of the work material with CFCs or organic solvents, and it is a measure to prevent air pollution, which is currently a major problem, and it will significantly contribute to environmental problems. become.

[Brief description of drawings]

FIG. 1 is a view showing the shape of a material obtained by joining ceramics and a base material, and FIGS. 2 and 3 are views showing the shapes of a round punch and a square punch, which are created by processing the material shown in FIG. 1, respectively. is there. 1: Ceramics, 2: Base material

Claims (2)

[Claims] 1. A tetragonal type ZrO to which Y ₂ O ₃ and Nd ₂ O ₃ are added in combination.
ZrO ₂ -based ceramics composed of ₂ : 60 to 80 vol% and Al ₂ O ₃ : 20 to 40 vol% and sintered by HIP.
Kg / mm ² or more, fracture toughness: 7.5 MN / m ^1.5 or more, Vickers hardness: 1300 or more The cutting edge made of ceramics is joined to the base material composed of steel or cemented carbide. Punching tool characterized by. 2. The punching tool according to claim 1, wherein the ceramic is a ceramic having an electric resistivity of 1 × 10 ⁻² Ω · cm or less.