JP2003019523A - Upper die for press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an upper die for presses which is provided with a tip made of KHA 33N as a punch tip. SOLUTION: In the upper die for presses which is provided with the punch tip in the tip part of a punch body, the punch tip consists of the nitrided powder high-speed steel and is nitrided. The material of the punch tip is KHA 33N and TiCN coating is performed on the punch tip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upper die for punching or forming a work such as a metal plate, and more particularly, to a tip of a punch body made of a nitride powder high speed steel. The present invention relates to an upper mold having a punch tip.

[0002]

2. Description of the Related Art Since, for example, a turret punch press as a press can be automatically operated, an unmanned operation at night is often performed. In this case, if the tool life is short,
The tool life is easily reached during automatic operation, and defective products may occur during automatic operation.

By the way, the tool wear that affects the tool life is a form of a mixture of abrasive wear and adhesive wear, and it is necessary to improve both forms of wear at the same time. The abrasive wear can be reduced by improving the tool hardness, but if the tool hardness is improved, there is a problem that brittleness increases and chipping easily occurs.

The adhesive wear is caused by friction between the tool and the work material. In this case, adhesion wear is suppressed by subjecting the contact surface of the tool to appropriate surface treatment for surface modification or by interposing a foreign material. However, after the surface treatment, the tool may undergo a large dimensional change or the surface roughness may deteriorate. Further, when coating is performed, peeling of the coating film may occur due to insufficient adhesion strength of the coating film, which makes it difficult to effectively suppress adhesive wear.

[0005]

By the way, as an upper die used for a press machine, an upper die having a cemented carbide tip or a high speed tip at the tip of a punch body has been developed. There is. Examples of high-speed tool materials include ultra-high toughness powder high speed steel HAP5R (Hitachi Metals), high toughness and high strength nitriding powder high speed steel KHA3VN (Kobe Steel),
Nitride powder high speed steel KHA33N (Kobe Steel) and high toughness matrix high speed steel MH85 (Daido special steel) which are excellent in adhesion resistance are known. When this type of high speed steel is used for a cutter, a mold, etc., it is used after being subjected to heat treatment such as quenching and tempering. For example, in order to extend the life of the upper mold of a press, Further improvement is desired.

[0006]

The present invention has been made in view of the above problems, and the invention according to claim 1 is an upper die for a press having a punch tip at the tip of a punch body. The punch tip is made of nitrided powder high speed steel and is nitrided.

According to a second aspect of the invention, in the upper die for press according to the first aspect, the material of the punch tip is K.
It is made of HA33N.

According to a third aspect of the present invention, in the upper die for press according to the first or second aspect, the punch tip has a T shape.
iCN coating is performed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An upper mold having a tip of a punch body integrally provided with a chip of cemented carbide, high speed steel or the like is already known, but for example, punching of a difficult-to-machine material such as a stainless steel plate is performed. However, since the tool life is relatively short, further improvement is required. Therefore, as the tool material, ultra-high toughness powder HSS HAP5R (Hitachi Metals), high toughness, high-strength nitriding powder HSS KHA3VN (Kobe Steel), nitriding powder HSS KHA33N (Kobe Steel) with excellent adhesion resistance, and high toughness matrix Using HSS MH85 (Daido special steel), an experiment was conducted to determine which tool material is suitable for the mold.

In the experiment, a general upper die and a lower die are used as the upper die and the lower die, and the various high speed steels are provided at the tip of the punch body 1B in the upper die (punch) 1. The punch chip 1C is appropriately welded and integrated, and the various high speed steels are appropriately welded and integrated as the die chip 3C on the upper surface of the die body 3D of the lower die (die) 3.

The shape of the punch tip 1C is as follows.
As shown in FIG. 1, the cross-sectional shape is square and the diagonal corners are R = 0.2 mm and R = 0.5 mm, respectively.
It is formed on. The shape of the die hole 5 in the die 3 for punching a work (workpiece) in cooperation with the punch tip 1C is a square, and diagonal corners are R = 0.4 mm and R =, respectively. It is formed to 0.7 mm and the clearance C between the punch chip 1C and the die hole 5 is
Is formed to have C = 0.2 mm.

As a work to be punched by the punch chip 1C and the die hole 5 having the above-mentioned shapes, the plate thickness t =
2 mm of SUS304 was used.

The punching process of the work is carried out by using the upper die and the lower die equipped with the punched and die chips of the various high speed steels which are heat-treated such as quenching and tempering.
The results of observing the occurrence of wear and chipping of the punch chip 1C and die chip 3C after 0 times by SEM (scanning electron microscope) photographs are as shown in FIGS. 2 and 3. FIG. 2 is a shape showing an observation situation of a punch edge R = 0.2 mm and a die edge R = 0.4 mm.
FIG. 3 shows punch edge R = 0.5 mm, die edge R = 0.7.
It is a shape showing the observation situation of the mm portion.

Then, at this time, the surface roughness of the portion about 0.5 mm above the straight side of the punch blade portion, which is the intersection of the lower surface and the side surface of the punch tip 1C, is measured by using a surface roughness measuring instrument. The result of the measurement was as shown in FIG.

Further, when the blanking was carried out 20000 times, blanks were taken every 2000 times, and the burr height of each corner portion of each blank was measured by a laser focus displacement meter. The results are shown in FIG. there were.

As is clear from the above results, MH85 was punched about 3000 to 4000 times, and HAP5
R is a punching process of about 5000 to 6000 times and R =
Large chipping occurs in each punch corner portion of 0.2 mm and R = 0.5 mm, and the burr height is as large as 100 μm or more due to the chipping. KHA
With respect to 3 VN, chipping occurs on the R = 0.2 mm side in the punching process of about 12,000 times to 14,000 times, and the burr height suddenly increases due to this.

On the other hand, no significant chipping was observed in KHA33N, and the burr height was 100.
It was about μm. However, in KHA33N,
As shown in FIG. 2, the corner portion of R = 0.2 mm has a chamfered shape, and the number of rotations is 4000 to 60 times.
Since the burr height of the corner portion of R = 0.2 mm suddenly increased by punching around 00 times, this 4000
It is considered that small chippings occurred at about 1 to 6000 times.

Therefore, the surface roughness measurement result (FIG. 4)
Considering also, HAP5R, KHA3VN, KHA3
It can be seen that in the 3N and MH85 material tools, KHA33N has the longest life with respect to difficult-to-machine materials such as stainless steel plates.

As already understood, it is found that it is desirable to use KHA33N as a mold tool for press working of SUS or the like in order to prolong the service life. Therefore, next, in order to improve wear resistance, KHA33N
The punch tip is coated with TiCN to a cutting tool with a typical coating thickness of 20.
After punching 000 times, punch R = 0.2
mm, part of die R = 0.4 mm and punch R = 0.5
The shape of the cutting edge at the portion of mm and die R = 0.7 mm is as shown in FIG. 6, and the measurement result of the tool surface roughness is as shown in FIG. 7. The burr height at that time is as shown in FIG.

As is clear from the above results, although the occurrence of large chipping is not recognized, as can be understood from FIG. 6 (A), relatively large wear is recognized from the cutting edge portion to the side surface, and the burr height is high. As a result, a burr of about 80 μm was observed. Regarding surface roughness,
The rate of change with respect to the roughness before the test was not so large, and improvement in wear resistance was observed.

That is, KHA33 is used as a punch tip.
It can be seen that when N is used, it is preferable to apply not only the heat treatment for quenching and tempering but also the TiCN coating.

The various types of high speed steels have a large hardness originally, but the shape of the cutting edge as a result of performing the plasma nitriding treatment on the high speed steels and performing the punching process 20000 times in the same manner as described above is shown in FIG. As shown in FIG. 9 and FIG. 10, FIG. 9 shows the shape of the punch edge R = 0.2 mm and die edge R = 0.4 mm, and FIG. 10 shows the punch edge R = 0.5 mm and die edge R. The shape of the cutting edge at the portion of 0.7 mm is shown. The surface roughness is as shown in FIG. The measurement results of the burr height measured every 2000 punching processes are shown in FIG.

As can be understood from the above results, although the effect is recognized before and after the nitriding treatment, KHA3VN and KHA33N have burr heights of 100 μm or less even after punching 20000 times. It was The shape of the cutting edge did not change so much even though the punching was performed 20000 times.
It was only 3N.

In the KHA33N punch tip, the burr height of the blank was about 40 μm, which was a very small value even after the punching was performed 20,000 times.
So, when I tried punching until it reached the end of its life, it was possible to punch up to 37,000 times. Immediately after that, chipping was observed at the punch edge R = 0.2 mm, and the burr height was sharp. It became big.

Therefore, when punching a difficult-to-machine material such as SUS, a KHA33 punch tip is used.
It can be seen that it is desirable to use N after nitriding treatment.

By the way, looking at the surface roughness of FIG.
It can be seen that it is larger than the surface roughness when iCN is coated (FIG. 7). In other words, it can be understood that the surface roughness is improved by applying the TiCN coating. As a result, when KHA33N is used as a punch tip, nitriding treatment is performed, and then TiCN coating is performed, so that the occurrence of chipping and the increase in surface roughness can be effectively prevented. is there.

[0027]

As can be understood from the above description, in the present invention, since a nitrided high-speed steel having a high hardness originally is provided with a punch tip subjected to a nitriding treatment, the occurrence of chipping or It is possible to suppress wear and prolong the life of the tool. At this time, by adopting KHA33N as the material of the punch tip, the life of the tool is remarkably extended, and by coating with TiCN, the deterioration of the surface roughness can be effectively prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a relationship between a cross-sectional shape of a punch chip and a shape of a die hole of a die.

FIG. 2 is an explanatory diagram showing a shape of a cutting edge when punching is performed 20000 times using various types of high speed steel.

FIG. 3 is an explanatory diagram showing a shape of a cutting edge when punching is performed 20000 times using various types of high speed steel.

FIG. 4 is an explanatory diagram showing a measurement result of surface roughness.

FIG. 5 is an explanatory diagram showing the relationship between the number of blank punches and the burr height.

FIG. 6 is an explanatory view showing the shape of a cutting edge when KHA33N is TiCN coated and punched 20,000 times.

FIG. 7 is an explanatory diagram showing a measurement result of surface roughness of the above.

FIG. 8 is an explanatory diagram showing the relationship between the number of punches and the burr height in the above.

FIG. 9 is an explanatory diagram showing the shape of a cutting edge when punching is performed 20000 times using various types of high speed steel.

FIG. 10 is an explanatory diagram showing a shape of a cutting edge when punching is performed 20000 times using various types of high speed steel.

FIG. 11 is an explanatory diagram showing measurement results of surface roughness.

FIG. 12 is an explanatory diagram showing the relationship between the number of blank punches and the burr height.

FIG. 13 is an explanatory diagram showing the relationship between the number of punches and the burr height.

[Explanation of symbols]

1 ... Punch (upper mold) 1B ... Punch body 1C ... Punch chip 3 ... Die (lower mold) 5 ... Die hole

Claims (3)

[Claims] 1. An upper die for press having a punch tip at the tip of a punch body, wherein the punch tip is
An upper die for press, which is made of high-speed nitrided powder steel and is nitrided. 2. The upper die for press according to claim 1, wherein the material of the punch tip is KHA33N. 3. The upper die for press according to claim 1, wherein the punch tip is subjected to TiCN coating.