JPH07204938A - Wire discharge cutting method for catalyst carrier made of metal - Google Patents

Abstract

PURPOSE:To cut off a metal material at a practical speed without damaging the cut section so as to increase productivity and production yield by setting current value and discharge time in discharge deformation independently at proper values. CONSTITUTION:In the cutting of a metal catalyst-carrier 1 (so called honeycomb body or metal carrier), first a current value (i) is set to the upper limit current value i1 at which no crack is produced. Next a discharge time is adjusted with the current value fixed at the current i1 to set at a discharge time tau1 at which a discharge energy does not cause the breakage of a wire 2. Then discharge intervals are set at the lower limit at which no wire breakage is produced. Thus a metal material of special form with honeycomb cross-section can be cut off at a practical speed by wire discharge cutting method without damaging the material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metallic honeycomb body used in an exhaust gas treatment apparatus for an internal combustion engine such as an automobile exhaust gas purifying apparatus, or a metal carrier in which the metallic honeycomb body is fitted to a metallic outer cylinder. In the specification, the metallic catalyst carrier is a generic term for these) and relates to a method for cutting by a wire discharge cutting method.

[0002]

Gas emitted from an internal combustion engine such as an automobile engine contains harmful components such as CO and NOx, and a catalyst such as platinum or palladium is used to render them harmless. . The catalyst has a honeycomb cross section and is supported by a cylindrical metal catalyst carrier having holes penetrating in the lengthwise direction, and the exhaust gas is passed through the carrier to perform the treatment.

The metal catalyst carrier is usually wound in a spiral shape by stacking a flat plate 11 and a corrugated plate 12 as shown in FIG.
A cylindrical honeycomb body 13 as shown in FIG.
As shown in (c), the metal carrier 15 is fitted to the outer cylinder 14 having both the function as a container and the function as a structural strength body.
Used. The metal carrier 15 is manufactured in various sizes according to the application.
The diameter, the length, and the mesh size are determined by the length and width of the flat plate 11 and the corrugated plate 12, and the wave height and the corrugated width of the corrugated plate 12, which are fitted into the outer cylinder 14 having a predetermined size.

In the meantime, in order to manufacture metal carriers of various lengths, it is necessary to prepare flat plates, corrugated plates and outer cylinders of various sizes corresponding to them, and when the flat plates and corrugated plates are stacked and wound up. There is a problem that workability is poor due to positioning for winding both edges in line. Therefore, it has been considered that a long honeycomb body or a metal carrier is cut to manufacture a plurality of metal catalyst carriers. However, mechanical cutting by sawing or the like forms a honeycomb body.
Burrs and sags are generated on flat plates and corrugated plates having a thickness of not more than μm, which impairs the functionality as a catalyst carrier for treating exhaust gas.

Conventionally, a wire electric discharge cutting method has been known as a method for cutting without causing processing distortion. Although this method can perform strain-free precision processing, it has a drawback that the processing speed is slow, but in recent years, the technology for preventing wire breakage, which was the rate-determining speed of the processing speed, has been improved, and the discharge energy has been increased. It has become possible to increase the processing speed by applying it to cutting of various parts.

[0006]

The present inventor can cut various honeycomb bodies and metal carriers as shown in FIG. 3 by the wire discharge cutting method without causing burrs and sags. When the discharge energy was increased so that it could be cut at a desired speed, cracks occurred in the honeycomb-shaped metal flat plate or metal corrugated plate.

The present invention applies a wire discharge cutting method to the cutting of a special material such as a honeycomb body or a metal carrier in the manufacture of a metal catalyst carrier used for an automobile exhaust gas purifying apparatus, etc. The purpose is to improve productivity and manufacturing yield by cutting at a practical speed without giving.

[0008]

The present invention for achieving the above object provides a honeycomb body formed by spirally winding a corrugated metal plate and a flat metal plate into a cylindrical shape, or a honeycomb body made of a metallic material. In a method of cutting a metal carrier fitted in a cylinder by a wire discharge cutting method, a current value and a discharge time in one discharge waveform are independently set to appropriate values, respectively. This is a wire discharge cutting method.

[0009]

FIG. 1 shows an example of the wire discharge cutting method which is the object of the method of the present invention. While the wire 2 is running on the metallic catalyst carrier 1 (generally referring to the honeycomb body 13 or the metal carrier 15 as shown in FIG. 3), the wire 2 is discharged in water to cut it in a saw-tooth manner. The metal catalyst carrier 1 is held by a carrier holder 7 and sent in the direction of the arrow by a servo mechanism (not shown). The wire 2 is wound around the take-up reel 6 from the supply reel 3 via the brake 4 and the take-up roller 5, and is stretched in a straight line between the brake 4 and the take-up roller 5 to form the metal catalyst carrier 1 Abut. Wire 2 and carrier holder 7
During this period, a pulse current 9 is supplied from the machining power source 8 to discharge the two in water.

As the wire 2, brass, tungsten,
A fine wire such as molybdenum is used. Deionized water is used as the water, and the electric conductivity is controlled so that discharge is likely to occur.
Although water can be supplied to the processed portion by a nozzle, in the present invention, it is preferable to immerse the processed portion in water because the workpiece has a honeycomb cross section.

In the wire discharge cutting method of the present invention, the current value i in one discharge waveform as shown in FIG. 2 is obtained.
And the discharge time τ are independently changed and set to appropriate values. The metallic catalyst carrier targeted by the present invention has a special form as shown in FIG.
When cutting by the wire discharge cutting method, if the discharge energy is simply increased to increase the cutting speed, the thickness is 100 μm.
The following thin and corrugated plates were cracked.

The present inventor studied the conventional wire discharge cutting method, and found that the discharge current value and the discharge time were integrally changed. That is, regarding the discharge waveform of one shot, as shown in FIG. 2B, when the current value is increased from the discharge waveform of the current value i ₀ and the discharge time τ ₀ to i ₂ , the discharge time becomes τ ₂ . It was designed so that the discharge waveform would change in a similar fashion. That is, in the conventional wire discharge cutting method, since the cutting ability is related to the discharge energy (proportional to i × τ), the method of integrally adjusting the current value and the discharge time has been adopted.

However, when cutting the metal catalyst carrier which is the object of the present invention, if the discharge energy is increased in order to increase the cutting speed in this way, the problem that cracks occur as described above occurs. It was As a result of the inventors independently cutting the current value i and the discharge time τ for one discharge waveform, the size and frequency of cracks generated in thin flat plates and corrugated plates with a thickness of 100 μm or less. Was found to be affected by the current value i.

Therefore, at the time of cutting, as shown in FIG. 2A, first, the current value i is set to the upper limit current value i ₁ at which a crack does not occur.
Set to. This current value is the thickness of the flat plate and corrugated plate constituting the metal catalyst carrier to be cut, the size of the honeycomb,
Since it changes depending on the components of each plate, the diameter of the carrier, etc., when the target material changes, the appropriate value is adjusted accordingly. Next, the discharge time τ is adjusted while the current value is fixed at i ₁ , and the discharge time τ ₁ is set so that the discharge energy becomes the upper limit at which wire breakage does not occur. Then, the discharge interval (discharge cycle) is set to the lower limit at which wire breakage does not occur.

According to such a method of the present invention, a metal material having a special shape having a honeycomb cross section can be cut by a wire discharge cutting method at a practical speed without damaging the material. .

[0016]

[Example] Thickness of ferritic stainless steel 0.05
Table 1 shows an example in which a honeycomb body in which a flat plate and a corrugated plate of mm are stacked and spirally wound is immersed in deionized water for a metal carrier that is also fitted to an outer cylinder made of stainless steel with a ferrite diameter. Shown in 1. In Table 1, the current value, the discharge time, and the discharge cycle are all shown in the ratio of the conventional example.

In the conventional example, the current value and the discharge time cannot be independently changed and set, and in the conventional example cut in a practical time of 5.5 minutes, the flat plate and the corrugated plate constituting the carrier are Many cracks were generated. In the conventional example in which the discharge energy was lowered so that cracking did not occur, it took a long time to cut.

On the other hand, in the example of the present invention, the current value was set to 80% of the conventional example, the discharge time was set to 130%, and the cutting was practically performed in 5.5 minutes without generating cracks. The present invention example is obtained by cutting a larger-diameter carrier under the same conditions, and the present invention example is obtained by slightly extending the discharge time at the same current value as. In all cases, good cross sections were obtained without cracks. As a result, when the diameter of the carrier becomes large, the current value is not changed and the discharge time is lengthened to compensate for the discharge energy lost in the material to be cut, greatly extending the cutting time without causing cracks. Was found to be suppressed.
In the example of the present invention, since the wire breakage occurred when the discharge time was longer than this, the upper limit of the discharge time is
Set based on the presence or absence of wire breakage.

[0019]

[Table 1]

[0020]

According to the method of the present invention, the metal honeycomb body 13 or the metal carrier as shown in FIG. 3 can be cut at a practical speed without damaging the cut surface by the wire discharge cutting method. Wire discharge cutting can be automated, and one material can be cut at multiple points at the same time, improving productivity and manufacturing yield in the production of metal catalyst carriers used in automobile exhaust gas purification equipment, etc. Can be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a method of the present invention.

FIG. 2 is a diagram showing one discharge waveform in the method of the present invention and the conventional method.

[Fig. 3] Fig. 3 (a) is a perspective view illustrating a method of winding a honeycomb body which is a target of the present invention. (B) It is a perspective view of the honeycomb object which is the object of the present invention. (C) It is a perspective view of the metal carrier which is the object of the present invention.

[Explanation of symbols]

 1: Metal catalyst carrier 2: Wire 3: Supply reel 4: Brake 5: Take-up roller 6: Take-up reel 7: Carrier holder 8: Processing power supply 9: Pulse current 11: Flat plate 12: Corrugated plate 13: Honeycomb body 14: Outer cylinder 15: Metal carrier

Continuation of the front page (72) Inventor Toru Utsumi 2-6-3 Otemachi, Chiyoda-ku, Tokyo Shin Nippon Steel Corporation

Claims (1)

[Claims] 1. A wire corrugated plate and a metal flat plate are spirally wound to form a cylindrical honeycomb body, or a metal carrier obtained by fitting the honeycomb body to a metal outer cylinder is subjected to a wire discharge cutting method. In the cutting method, the current value and the discharge time in one discharge waveform are independently set to appropriate values, respectively, and the wire discharge cutting method of the metal catalyst carrier.