JPH0292466A - Plasma arc cutting method - Google Patents

Abstract

PURPOSE:To obtain the cut surface to which no dross adheres by performing piercing to a cutting material, and cutting it by forming at least one closed circuit between its position and a graphic which becomes a product. CONSTITUTION:A dross-free speed range in which no dross adheres in accordance with plate thickness of a cutting material exists. As for this speed range, the dross-free speed range is wider in the case of executing a running start from the end face of the cutting material than in the case of executing a piercing start from the surface of the cutting material. In this state, piercing is performed to a prescribed position 3 on the cutting material 1, the position 3 is set as a start position of cutting and a closed circuit 4 is formed between the position and graphic 2, and by allowing it to intersect with a cut groove 6 which is cut already in an intersection 5 of this closed circuit 4, notching by a running start method in which the cut groove 6 is an end face of the cutting material 1 is executed. In such a way, a continuous adhesion of a dross is cut off, and a product to which no dross adheres can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a plasma cutting method, and more particularly to a plasma cutting method in which a hole is drilled in a material to be cut and cutting is started from that position.

<Prior Art> Plasma cutting is a method for cutting materials such as steel or stainless steel. In the above-mentioned plasma cutting method, there are a running start method in which a cut is made from the end face of the cut material using a plasma torch adjusted to a predetermined speed, and a running start method in which a cut is made from the end surface of the cut material with a plasma torch adjusted to a predetermined speed.
There is a piercing start method in which piercing is performed (referred to as piercing J) and an incision is made from that position.

The running start method is generally used when cutting a material to be cut, and the piercing start method is generally used when cutting a material.

When performing pattern cutting using the piercing start method, as shown in FIG. , the torch's transition path is set so that the angle of incidence with respect to the figure is small.

Further, the cutting speed in the plasma cutting method is set to a standard speed that is optimal for the material, plate thickness, etc. of the material to be cut. When the cut material is cut at a standard speed set for the cut material, a cut surface with no dross attached to the lower surface of the cut material and of constant quality can be obtained.

<Problems to be Solved by the Invention> When a cutting material is cut by the plasma cutting method described above, dross containing a melt and oxides of the cutting material is generated. The dross is discharged from the kerf formed in the cut material and may adhere to the lower surface of the cut material.

Dross adhesion to the cutting material tends to occur when the actual cutting speed is lower than the standard speed (especially when using the piercing start method, the cutting speed at the piercing position is approximately Oam/+sin). , While this speed is raised to the standard speed, dross continues to adhere to the cutting material, and even when the cutting speed reaches the standard speed, newly generated dross adheres to the dross already attached to the cutting material. A so-called dross dragging phenomenon occurs.

For this reason, there is a problem in that dross adheres to the product after cutting, and extra man-hours are required for post-processing.

An object of the present invention is to provide a plasma cutting method that overcomes these drawbacks.

<! 1. Means for Solving Problems> In order to solve the above problems, the plasma cutting method of the present invention involves drilling a hole in a cut material and forming at least one closed circuit between the hole and the shape to be a product. It is characterized by the fact that it can be cut by

<Operation> According to the above means, by forming and cutting at least one closed circuit between the piercing position and the figure to be the product, the continuous adhesion of dross, that is, the dross dragging phenomenon, is cut off. This makes it possible to obtain a product free of dross adhesion.

That is, when cutting a figure that will become a product from a piercing position, by forming a closed circuit between the piercing position and the figure, the cutting process is not substantially made in one stroke, and the cutting speed is increased from the piercing position. By cutting to the intersection point of the closed circuit, and making a cut using the running start method using the cut groove already cut at the intersection point as the end face of the cut material, the material will adhere to the cut material between the piercing position and the intersection point of the closed circuit. The dross thus formed is cut off when it intersects the kerf at the intersection. When cutting is performed by the running start method using the kerf as the end face of the material to be cut, no dross adheres even if the cutting speed is the same.

<Example> An example of a plasma cutting method to which the above means is applied will be described with reference to the drawings.

FIG. 1 is an explanatory diagram of the present cutting method, and FIG. 2 is a diagram showing a dross-free speed range.

When cutting a material by plasma cutting, there is a so-called dross-free speed range in which dross does not adhere to the material depending on the thickness of the material. As shown in the experimental results in Figure 2, this speed range differs depending on whether running starts from the end face of the cut material or when piercing starts from the surface of the cut material, and the dross-free speed range depends on the running start. It turns out that the case is wider than the case with piercing start.

That is, in Figure 2, when using a running start, dross-free occurs in the speed range surrounded by the curves ■ and ■, and when using a piercing start, ■
The speed range surrounded by the curves of and ■ is dross-free.

The reason for this is that when cutting material is cut at a speed slower than the standard speed, dross adheres to the material, and when dross adheres to the material, the viscosity and surface tension of the newly generated dross cause the dross to be removed from the material. This is because a so-called dross dragging phenomenon occurs in which dross adheres one after another, and as a result, dross continues to adhere even if the cutting speed becomes the standard speed.

Therefore, in order to stably start and continue cutting the material in a dross-free state, it is necessary to use the running start method to make cuts from the end surface of the material using a plasma torch adjusted to a standard speed. is the most effective. However, when cutting the material to be cut, if a running start is performed from the end face, distortion will occur due to thermal effects or the release of internal stress in the material to be cut, making it impossible to cut the shape into an accurate shape. do not have.

Therefore, in the plasma cutting method of the present invention, as shown in FIG. The cut groove 6 is substantially cut by forming a closed circuit 4 on the way to the figure 2 with the starting position of cutting, and intersecting the cut groove 6 which has already been cut at the intersection 5 of the closed circuit 4. An incision is made using the running start method on the end face of the material 1.

That is, at piercing position 3, the cutting speed is approximately Q m
Piercing is performed in a m/win state, and after the piercing is completed, cutting grooves 6 are formed while increasing the cutting speed, and the closed circuit 4 is cut, and the cutting of the closed circuit 4 is completed and the intersection point 5 is reached. Sometimes, the cutting speed is set to be in a dross-free range, at least for the running start shown in FIG.

When the cutting path intersects with the kerf 6 at the intersection point 5, the continuous cutting from the piercing position 3 to the intersection point 5 is broken, and therefore the dragging phenomenon of the dross attached to the lower surface of the cut material 1 is cut off. . Then, from the intersection point 5, a new cutting is started using the running start method using the kerf 6 as the end face of the cutting material 1.

At this time, since the cutting speed is within the dross-free range at the running start, the dross generated by the newly started cutting is discharged from the kerf 6 and does not adhere to the cutting material l.

<Effects of the Invention> As explained in detail above, according to the plasma cutting method of the present invention, at least one closed circuit is formed and cut between the piercing position and the figure to be a product, thereby reducing dross. The continuous adhesion of dross is cut off, thereby making it possible to obtain a product free of dross adhesion.

That is, by substantially breaking the cut at the intersection of the closed circuit, the dragging phenomenon of dross adhering to the cut material is cut off, and by making a new cut using the running start method at the intersection, the dross is removed. You can cut free shapes.

Therefore, it is possible to obtain a product without adhesion of dross, and therefore the number of steps for post-processing can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the present cutting method, FIG. 2 is a diagram showing a dross-free speed range, and FIG. 3 is a cutting diagram of the conventional cutting method. 1 is a cutting material, 2 is a figure, 3 is a piercing position, 4 is a closed circuit, 5 is an intersection, and 6 is a kerf. Patent applicant Koike Oxygen Industry Co., Ltd.

Claims (1)

[Claims] A plasma cutting method characterized in that a hole is drilled in a material to be cut, and at least one closed circuit is formed from the hole to a figure to be a product.