JP2000237886A - Laser piercing method - Google Patents

Abstract

(57) [Summary] When dies are cut in a mold, piercing is smoothly performed to form a hole that penetrates in the thickness direction of the cut material as a starting point of the cutting. A focal point O of a laser beam 1 condensed by a lens 4 provided on a laser torch 3 is lowered from a position separated upward from a surface of a workpiece 5 to a position where the laser beam 1 enters the inside in the thickness direction and light is emitted. 2Hz to 20Hz along axis 2
Vibration in the range of When the focus O is applied to the base material of the material to be cut, the base material melts and evaporates to form a depression 12. Next, the focus O is separated from the base material to stop the melting of the base material,
In this state, the melt is removed from the depression 12. When the position of the focal point O enters the thickness direction of the workpiece 5 while repeating such an operation, the hole 13 penetrating in the thickness direction of the workpiece 5 can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser piercing method capable of forming a hole serving as a starting point of cutting when a material to be cut is die-cut.

[0002]

2. Description of the Related Art In laser cutting, a focal point of a laser beam having a high energy density is set at a predetermined position in the thickness direction of a material to be cut and irradiated, and the position of the focal point is set along a target cutting line. By moving, the material to be cut is cut by continuing the physical reaction of instantaneously melting and evaporating and removing the base material at and near the focal point. For this reason, desired cutting can be performed without limiting the material of the material to be cut.

For example, when a steel sheet is used as a material to be cut,
The focal point of the laser light is set at a position slightly in the thickness direction than the surface of the steel sheet, and when the laser light is irradiated in this state, the steel sheet is slightly shifted from the focal point to the surface side and the thickness direction. The base material in the portion melts instantaneously and evaporates almost simultaneously. For this reason, depressions or grooves are formed in the steel sheet due to evaporation of the base material. Therefore, the workpiece can be cut by moving the focal point along the target cutting line so that the evaporation of the base material accompanying the irradiation of the laser beam is continued.

[0004] However, the laser beam irradiation site may be filled with the vapor of the base material, making it impossible to efficiently apply energy to the material to be cut. For this reason, it is common to inject a gas along the laser beam so that the vapor of the base material can be eliminated by this injection energy. In particular,
If the material to be cut is an iron-based metal and the combustion reaction of the base material is expected, a part of the base material is burned by injecting oxygen gas along the laser beam, and the combustion is performed by the injection energy of oxygen gas. By eliminating the product, cutting can be performed while excluding a wide range of base material starting from the focal point of the laser beam in the material to be cut.

In the case of performing so-called die cutting for cutting figures having various shapes from a material to be cut, a hole penetrating in the thickness direction is formed at a position other than the product in the material to be cut (piercing).
Then, the hole is generally cut starting from the hole. In this case, the laser torch is arranged opposite to the position where the hole is formed in the material to be cut, and a part of the base material of the material to be cut is melted by irradiating laser light from the position to remove the material. The depression formed on the surface of the material to be cut is grown in the depth direction to form a penetrating hole.

[0006] In the case of forming a hole penetrating in the thickness direction by piercing the material to be cut, until the hole is penetrated, the molten base material is injected with oxygen gas by the injection energy of the oxygen gas. Excluded from the surface. At this time, the melt of the base material may be scattered and adhere to the tip of the laser torch, or may enter the inside of the laser torch and damage the laser torch. For this reason, it is common to raise the laser torch without changing the position of the lens that focuses the laser light, thereby preventing the adhesion of the melt.

[0007]

By performing the piercing as described above, the adhesion of the melt to the laser torch can be reduced, but since the position of the focal point is fixed, it is formed on the material to be cut. It is not possible to smoothly remove the melt from the formed depression. For this reason, there is a problem that the time required for piercing becomes longer, which is a factor that increases costs.

An object of the present invention is to provide a laser piercing method that does not significantly increase the time required for piercing a workpiece.

[0009]

In order to solve the above-mentioned problems, a laser piercing method according to the present invention is directed to a method of irradiating a laser beam toward a material to be cut to remove a part of the material to be cut, and to remove the material in a thickness direction. A laser piercing method for forming a hole penetrating through the laser light, wherein the focal point of the laser light is oscillated in the range of 2 Hz to 20 Hz along the optical axis of the laser light. Is preferably raised or lowered with respect to the material to be cut.

In the above laser piercing method (hereinafter simply referred to as "piercing"), the focal point of the laser light is oscillated along the optical axis in the range of 2 Hz to 20 Hz, and the focal point of the laser light is higher than the upper surface of the material to be cut. Also, by lowering from a position separated upward to a position where it enters into the thickness direction of the material to be cut, a part of the base material of the material to be cut is melted and evaporated to be removed. Piercing can be performed.

That is, when the focal point of the laser beam is vibrated along the optical axis, and the focal point is formed on the base material of the material to be cut,
When the material to be cut is melted and evaporated and the focal point is separated from the base material of the material to be cut, the molten material and the evaporated material of the base material can be removed from the surface of the material to be cut. For this reason, the time required for piercing is reduced and the cost is not increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the piercing method will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a piercing method according to the present invention. FIG. 2 is a diagram illustrating an example of an apparatus that vibrates the focal point of laser light.

First, in carrying out the piercing method according to the present invention, an example of a mechanism for vibrating and raising and lowering the focus of a laser beam will be described with reference to FIG. In the figure, a laser beam 1 emitted from a laser oscillator (not shown) has a predetermined laser beam path 2 (optical axis 2).
The laser beam reaches the laser torch 3 and is condensed at a focal point O by a lens 4 provided on the laser torch 3, irradiates the workpiece 5 and removes a part of the base material of the workpiece 5. Melt and evaporate.

The material of the material to be cut 5 is not particularly limited. However, in the present embodiment, the workpiece 5 is a steel plate,
Oxygen gas adjusted to a predetermined pressure is injected from a nozzle 6 attached to the tip of the laser torch 3 to burn the base material melted by the irradiation of the laser light 1 and to melt the base material by the injection energy of the oxygen gas; By adopting a gas cutting process by removing the oxides and the like, the structure is such that good cutting can be continued.

To this end, a hose 7 connected to an oxygen supply device (not shown) is detachably attached to a nozzle 6 attached to the tip of the laser torch 3 and adjusted to a preset pressure via the hose 7. The supplied oxygen gas is supplied.

The device for moving the laser torch 3 is not particularly limited. That is, any cutting device used for ordinary gas cutting or plasma cutting may be used as long as it can follow the speed of laser cutting. In the present embodiment, a laser oscillator is mounted on a carriage mounted on a rail (not shown), and a laser torch 3 3 is mounted via a torch elevating device 9 configured to elevate and lower the torch.

The lens 4 is mounted on an elevating cylinder 10 provided inside the laser torch 3, and the elevating cylinder 10 is driven up and down by a vibrating motor 11 in the range of 2 Hz to 20 Hz. It is configured to vibrate at a frequency. The size (amplitude) of the reciprocating movement of the lens 4
Is not particularly limited, but is set to 10 mm in this embodiment.

The mechanism for oscillating the focal point O of the laser beam in the thickness direction of the workpiece 5 is not limited to the above-described structure. For example, the mechanism for reciprocating the laser torch 3 vertically. In addition, even when the lens 4 is vibrated, in addition to the vibration motor 11, vibration is applied by intermittent operation of a solenoid, vibration is applied by a cam, or vibration is applied by a linear drive. It can be realized by various mechanisms, such as applying vibration by changing.

The frequency at which the focal point O is oscillated is 2 Hz to 2 Hz.
It is set in the range of 0 Hz. This frequency is a value appropriately set so that a melt or an oxide of the base material can be removed in a preferable state when piercing the workpiece 5, and the thickness of the workpiece 5 is large. In this case, the frequency is set to be large, and when the thickness is small, the frequency is set to be small. The setting of the frequency is performed by controlling a drive signal from a control unit (not shown) that controls the vibration motor 11.

Next, the piercing method will be described with reference to FIG. In the piercing method according to the present invention, the focal point O of the laser beam 1 is vibrated along the optical axis 2 or the focal point O is raised or lowered with respect to the workpiece 5 while vibrating, so that the The portion is melted and evaporated to form a depression 12, and the depression 12 is grown to form a hole 13 penetrating in the thickness direction.

When forming the depression 12, the focal point O of the laser beam 1 is applied to the material 5 to be melted to evaporate and evaporate the base material at the irradiated portion, and the molten base material is injected by injecting oxygen gas. Is burned, and the focal point O of the laser beam 1 is separated from the depression 12, so that the melting of the base material is temporarily stopped, and the generated melt is discharged from the depression 12 by the injection energy of oxygen gas. , Piercing can be performed in good condition.

Whether the piercing is performed with the focus O of the laser beam 1 simply vibrated, the piercing is raised while vibrating, or the piercing is lowered while vibrating is set according to the thickness of the material 5 to be cut. . That is, when the thickness of the material to be cut 5 is large, it is preferable to perform piercing by lowering the focal point O of the laser beam 1 while vibrating along the optical axis 2. It is preferable to raise the focal point O of the laser beam 1 while oscillating the same. Further, the material to be cut 5
When the thickness of the laser beam 1 is moderate, good piercing can be performed by simply oscillating the focal point O of the laser beam 1.

In the following embodiment, in the initial state, the laser beam 1 is set at a position upwardly separated from the surface of the workpiece 5 and the focal point O of the laser beam 1 is oscillated along the optical axis 2 in the plate thickness direction. A method for lowering the camera is described.

FIG. 1A shows a state in which the focal point O of the laser beam 1 is at a position separated upward from the surface of the workpiece 5. In this state, no dent is formed on the surface of the material 5 to be cut by the laser beam 1, and for example, a coating layer such as rust prevention coating, rubber lining, or synthetic resin lining (not shown) is formed on the surface of the material 5 to be cut. In such a case, the material forming the coating layer can be removed by melting and evaporating.

Therefore, even when a coating layer that inhibits piercing is formed on the surface of the material 5 to be cut, the focal point O of the laser beam 1 is separated upward from the surface of the material 5 to be cut. By setting to, the coating layer can be removed, and it is possible to pierce the workpiece 5 having the base material exposed on the surface.

FIG. 3B shows that the laser beam 1 is driven by driving the elevating motor 9 a to lower the laser torch 3.
3 shows a state in which the focal point O slightly enters the inside of the workpiece 5 in the thickness direction. In this state, the laser light 1
Is applied to the position where the focal point O is formed on the workpiece 5 and its vicinity, and the base material is melted and evaporated. In particular, since the oxygen gas is irradiated along the laser beam 1, the base material of the material to be cut 5 burns, a molten base material and a molten oxide are generated, and a depression 12 is formed.

As described above, when the dent 12 is formed or grown in the material 5 to be cut, that is, the focus O of the laser beam 1 is on the surface of the base material (the surface of the material 5 and the surface of the dent 12).
In contact with or near the surface, the melt of the generated base material scatters relatively flat along the surface while the depth of the depression 12 is shallow, but when the depth of the depression 12 becomes deeper, the inner wall of the depression becomes Splashes upward at a steep angle along.

Accordingly, as shown in FIG. 2B, when the focal point O of the laser beam 1 is at a position slightly in the thickness direction from the surface of the material 5 to be cut, the base material is moved by the applied energy. It melts vigorously, and a part of the molten material scatters outside from the depression 12. However, not all of the generated base material melt and molten oxide are instantaneously discharged from the depression 12, and most of the melt stays in the depression 12.

For this reason, the focal point O of the laser beam 1 is
By vibrating (moving up and down) along, the melt remaining in the depression 12 is eliminated. That is, as shown in FIG. 3C, the position of the focal point O is slightly raised from the state shown in FIG. 3B, thereby stopping the application of energy to the material 5 to be cut. Is stopped so that the generation of the melt is suppressed, and the melt in the depression 12 is removed by the injection energy of the oxygen gas subsequently injected.

The timing of oscillating the focal point O of the laser beam 1 along the optical axis 2 as described above is independent of the elevation of the laser torch 3 driven by driving the elevation motor 9a. Is not specially associated with the frequency of the focus O.

Subsequently, the laser motor 9a is driven to lower the laser torch 3, and the focus O is set to 2 Hz to 20 Hz.
By vibrating up and down along the optical axis 2 in the range of Hz, the depression 12 is grown as shown in FIGS.

Then, as a result of the depression 12 growing in the depth direction,
As shown in FIG. 1F, a hole 13 is formed in the workpiece 5 in the thickness direction. By forming the holes 13 penetrating in the thickness direction of the material 5 to be cut in this manner, the melt and the oxidized melt of the base material are discharged downward from the holes 13 and do not scatter upward.

When piercing the workpiece 5 as described above, the focal point O of the laser beam 1 is shifted to the optical axis 2
The frequency to be vibrated along may be in the range of 2 Hz to 20 Hz, and if it is 2 Hz or less, the effect of vibration does not appear at all,
If the frequency is higher than 20 Hz, the melting of the base material is stopped, and when the melt of the base material is eliminated by the oxygen gas, a new melt is generated before the metal material can be sufficiently excluded. Effect is impaired.

[0034]

As described above in detail, in the laser piercing method according to the present invention, a good piercing of the material to be cut is achieved by oscillating the focal point of the laser light in the range of 2 Hz to 20 Hz along the optical axis. Can be implemented.

In particular, by oscillating the focal point of the laser beam along the optical axis, the laser beam is lowered from a position separated from the surface of the material to be cut to a position in the thickness direction of the material to be cut. The base material is irradiated with light to melt the base material,
By continuing the operation of evaporating or burning and the operation of separating the laser beam from the base material to stop melting and evaporating and eliminating the melt, the elimination of the melt from the dent formed in the material to be cut is performed. It is possible to smoothly perform the piercing to form a hole penetrated in the thickness direction of the material to be cut.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a laser piercing method according to the present invention.

FIG. 2 is a diagram illustrating an example of an apparatus that vibrates a focal point of laser light.

[Explanation of symbols]

 O Focus 1 Laser beam 2 Laser beam path 3 Laser torch 4 Lens 5 Material to be cut 6 Nozzle 7 Hose 8 Traversing carriage 9 Elevating device 9a Elevating motor 10 Elevating cylinder 11 Vibration motor 12 Depression 13 Hole

Claims (2)

[Claims] 1. A laser piercing method for irradiating a material to be cut with a laser beam to remove a part of the material to be cut and to form a hole penetrating in a thickness direction, wherein the focus of the laser light is adjusted. A laser piercing method characterized by oscillating along the optical axis of laser light in a range of 2 Hz to 20 Hz. 2. The method according to claim 1, wherein the focal point of the laser beam is raised with respect to the workpiece or lowered with respect to the workpiece while oscillating the focal point of the laser beam along the optical axis. Laser piercing method.