JPH0752097A - Method of improving cutting blade of a rotary die or flat die - Google Patents

Abstract

PURPOSE:To enhance the durability and wear-resistance of a cutting blade of a rotary die or a flat die which are made of supper metal alloy with the use of electric discharge machining, by irradiating laser onto the cutting blade. CONSTITUTION:Micro holes or cracks (a) are present in a cutting blade 3 of a rotary die 1 or a flat die for cutting paper or sheet metal, at a surface thereof which is made of super-hard alloy by electric discharge machining. Although the cracks (a) are sometimes present in WC particles, the cracks (a) are usually present at a WC-Co interface. In order to improve this cutting blade 3, laser is irradiated to the surface layer thereof in order to elude Co which is then solidified again. Thereby, a defective surface processed by electric discharge is turned into an original condition before the electric discharge, that is, a condition in which no surface defect is present.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of modifying a cutting blade of a rotary die or a flat die for cutting paper or a thin metal plate.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a rotary die 1 for cutting a paper or a thin metal plate into a desired shape while rotating on its own axis. Rotary die 1
Is a cylindrical body 4 having a cutting blade 3 protruding from the outer peripheral surface thereof. For example, the cutting blade 3 is provided in a printing machine to cut printing paper, or
It is provided in various industrial machines to cut a thin metal plate or the like (the same components as those in this embodiment are designated by the same reference numerals).

Since the rotary die 1 cuts an object to be cut by the cutting blade 3 while rotating while being in contact with the object to be cut, it is generally made of a cemented carbide excellent in heat resistance and wear resistance. Produced. Further, because of the hard cemented carbide, the electric discharge machining is used to integrally form the cutting blade 3 on the outer peripheral surface of the body 4.

Further, there has been proposed a flat die 2 which cuts a paper or a thin metal plate into a desired shape by an elevating operation. The flat die 2 is one in which a cutting blade 3 is projectingly provided on a substrate 5, and is also provided in a printing machine to cut printing paper, or provided in various industrial machines to cut a thin metal plate or the like. (The same parts as those in the present embodiment are designated by the same reference numerals).

Since the flat die 2 descends and comes into contact with the object to be cut on the pedestal 6 and cuts the object to be cut by the cutting blade 3, it generally has heat resistance and wear resistance. Made of excellent cemented carbide. Further, since the cutting blade 3 is integrally formed on the substrate 5 because of the hard cemented carbide, electric discharge machining is used.

The present inventors have found that the surface to be machined of an electric discharge machined cemented carbide has minute holes or cracks a as shown in FIG.
After confirming that surface defects such as those occur, it is necessary to modify the surface to be processed by laser irradiation in order to remove these surface defects (1989 Precision Engineering Issued by the Japan Society for Precision Engineering in 1989). See the proceedings of the Autumn Meeting and Academic Lecture of the Society), and by carrying out this research on the manufacturing method of the cutting blade of the rotary die or the flat die, the cutting edge of the rotary die or the flat die excellent in durability and wear resistance is obtained. The present invention, which can be manufactured, has been completed.

[0007]

The gist of the present invention will be described with reference to the accompanying drawings.

A rotary die 1 or a flat die, characterized in that the cutting blade 3 of the cemented carbide rotary die 1 or flat die 2 formed by electric discharge machining is irradiated with a laser to modify the cutting blade 3. The present invention relates to the method for modifying the cutting blade of item 2.

[0009]

Since the cutting blade 3 of the rotary die 1 or the flat die 2 according to the present invention uses the above-mentioned modification method, the surface of the cutting blade 3 becomes smooth, so that the cutting blade 3 can be brought into good contact with the object to be cut and cut. Good cutting of cuts is achieved.

[0010]

EXAMPLES First, a reforming method will be described.

In this modification method, surface defects (fine holes and cracks a) generated in the surface layer of the surface to be processed by electric discharge machining are eliminated.
Only Co having a low melting point is melted and WC (solid state) is made into a free state to be removed. It is based on the finding that the melting point of the binder (Co) of the cemented carbide is extremely low compared to the carbide (WC) and the like.

Then, as this means, the surface layer is irradiated with a laser.

1 and 2 schematically show the principle of this reforming method step by step.

FIG. 1 shows a surface to be machined of an electric discharge machined cemented carbide. There are minute holes and cracks a. The crack a may occur in the WC particles, but in most cases, the crack a occurs at the WC-Co interface.

FIG. 2 shows a portion (C
It is the figure which displayed o) with the dot. Regarding the surface defects on the surface to be machined by electric discharge machining, when Co is melted by the laser irradiation and the Co is solidified again, a state before electric discharge machining, that is, a smooth state without surface defects is obtained.

The cemented carbide referred to here is a sintered material, which is a single carbide type material composed of WC and Co, WC,
It includes both of the double carbide type composed of TiC, T _a C, NbC and Co (Ni).

Commercial cemented carbide D20 material (WC90%, C
7%, TiC, TaC 3%: weight%) were used to produce the rotary die 1 and the flat die 2 in which the cutting blades 3 were integrally formed in a protruding manner by electric discharge machining. Specific electrical discharge machining conditions are shown in Table 1 below.

[0018]

[Table 1]

Innumerable cracks are formed on the outer peripheral surface of the cutting blade 3 in the form of minute holes and connecting them. The depth of the surface defect can be confirmed by actual measurement or energy during electric discharge machining.

Subsequently, in order to remove this defect, the cutting blade 3 was irradiated with laser. The laser irradiation has a risk of promoting surface defects such as cracks that are preliminarily formed on the electric discharge machined surface depending on the amount of heat input. Therefore,
It is desirable to perform laser irradiation with the minimum energy.

From this point of view, the laser irradiation employs a Gaussian distributed heat source as a heat source and a continuous method as an energy supply system, and preheats the rotary die 1 and the flat die 2 to 400 ° C. , Surface temperature Co
In order to match the melting point of 1100 ° C., a heat quantity equivalent to a temperature rise of 1100 ° C. is applied by a laser.

Further, the surface temperature depends on many parameters such as laser output and feed rate. Here, the laser output (500 W) and the feed rate (200 m / min) were kept constant, and the surface was modified by changing the defocus amount (the optimum positive value is 30 mm). Since the laser output is reduced by about 10% in the transmission system from the oscillator to the processing machine,
Set the output considering the value.

By using Ar as the processing gas, generation of excess combustion heat due to oxygen is prevented, and the effect of preventing oxidation of the laser irradiation surface is also exhibited.

Specific laser irradiation conditions are shown in Table 2 below.
Is the street.

[0025]

[Table 2]

It is desirable to irradiate the laser beam by reciprocally scanning the laser beam several times instead of irradiating the laser beam at one position in a concentrated manner.

After the laser irradiation, the surface defects generated during the electric discharge machining are completely removed. Further, the shape of the discharge crater is also blunted and modified to a smooth surface with few irregularities.

As described above, the cutting blades 3 of the cemented carbide rotary die 1 and flat die 2 shown in FIGS. 3 and 4 manufactured by the method according to this embodiment have excellent durability (fatigue strength) and wear resistance. Therefore, no chipping occurs during operation, and the cutting blade 3
Since the surface of the blade is smooth, it makes good contact with the object to be cut (especially in the case of the rotary die 1, the object to be cut is rotated and slid to cut the object to be cut, so the cutting blade The surface smoothness of No. 3 is very important.) And the rotary die 1 and the flat die 2 achieve good cutting for the object to be cut. Then, the laser irradiation according to the present embodiment also enables simplification of the polishing step, which is an essential step for manufacturing the cutting blade (when the surface shape is complicated in the only polishing step, it was very troublesome. The laser irradiation according to this embodiment also solves such a problem.

[0029]

As described above, the present invention can provide a rotary or flat die cutting blade excellent in durability, wear resistance and surface smoothness.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of this step.

FIG. 2 is a diagram illustrating the principle of this step.

FIG. 3 is a perspective view of a rotary die according to the present embodiment.

FIG. 4 is a front view of the flat die according to the present embodiment.

[Explanation of symbols] 1 rotary die 2 flat die 3 cutting blade

Claims (1)

[Claims] 1. A cutting blade of a rotary die or a flat die, characterized by irradiating a cutting blade of a cemented carbide rotary die or a flat die formed by electric discharge machining with a laser to modify the cutting blade. Reforming method.