JP2015098041A - Laser molding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lase molding apparatus that can carry out reliable dressing and truing to a molding object tool (10) with laser beams.SOLUTION: A first laser beam (21) for truing and a second laser beam (31) for dressing are radiated from a direction having an angle to the contact surface of the front face of the molding object tool (10). The energy density of a focus point (23) by the first laser beam (21) is set larger than the energy density of a focus point (33) by the second laser beam (31). A depth (T) from the front face of the molding object tool (10) included in the Rayleigh range of the first laser beam (21) is set shallower than a depth (T) from the front face of the molding object tool (10) included in the Rayleigh range of the second laser beam (31).

Description

  The present invention relates to a laser molding apparatus that performs truing and dressing with a laser beam on a molding tool including abrasive grains and a binder.

  Patent Document 1 describes performing truing (molding) and dressing (sharpening) on the surface of a grindstone with a laser beam. Patent Document 1 discloses a method of irradiating laser light from a tangential direction of a grindstone in both truing and dressing (FIG. 3), a method of irradiating laser light from a tangential direction of a grindstone in truing and a laser beam from a normal direction of the grindstone in dressing (FIG. 3). 4) A method of irradiating laser light from the normal direction of the grindstone for both truing and dressing (FIG. 5) is described. Patent Documents 2 to 5 also describe performing truing and dressing with a laser beam.

JP 2004-276144 A Japanese Patent Laid-Open No. 10-202530 JP-A-2005-52942 JP-A-2005-95992 JP 2007-160505 A

  By the way, the range in which the energy density of the laser beam is large is a range before and after the traveling direction around the condensing point (for example, corresponding to the Rayleigh range). Here, in FIG. 5B of Patent Document 1, laser light is focused on the surface of the grindstone by irradiating laser light from the normal direction of the grindstone to shorten the distance between the surface of the grindstone and the lens. It describes that dressing is performed with a larger diameter.

  However, in general, in grinding stone forming, an ultrashort pulse laser such as a femtosecond laser is required to obtain a sharp cutting edge with little thermal damage, and this ultrashort pulse laser is focused in the transparent member. Therefore, in dressing, even if the distance between the surface of the grinding wheel that is the object to be molded and the lens is shortened, the energy density in the vicinity of the focal point located inside the grinding wheel increases, and not only the surface of the grinding wheel but also the interior of the grinding stone. Will be processed. For this reason, dressing cannot be performed in a desired state simply by shortening the distance between the surface of the grindstone to be molded and the lens.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a laser forming apparatus capable of reliably performing dressing and truing with a laser beam on a tool to be formed.

  (Claim 1) A laser forming apparatus according to the present means is a laser forming apparatus that performs truing and dressing with a laser beam on a tool to be formed comprising abrasive grains and a binder that binds the abrasive grains. The laser processing threshold value of the abrasive grains is larger than the laser processing threshold value of the binder, and the laser molding apparatus includes a first laser beam for truing capable of ablating the abrasive grains and the binder, and the binder. Irradiating with a second laser beam for dressing that can be ablated and cannot process the abrasive grains, and the first laser beam and the second laser beam are in contact with the contact surface of the surface of the molding tool Irradiated from a direction having an angle, the energy density of the condensing point by the first laser light is set larger than the energy density of the condensing point by the second laser light, Depth from the surface of the object forming tools included in the Rayleigh range of serial first laser beam is set shallower than the depth from the surface of the object forming tools included in the Rayleigh range of the second laser beam.

  Here, truing is performed by a predetermined range before and after the traveling direction with the condensing point in the first laser light as the center. The dressing is performed in a predetermined range around the traveling direction around the condensing point in the second laser light. And the laser processing threshold value of an abrasive grain is larger than the laser processing threshold value of a binder. Furthermore, the energy density of the condensing point by the first laser light is set larger than the energy density of the condensing point by the second laser light. Thus, the first laser beam can process the abrasive grains and the binder, and the second laser beam can process the binder, but the abrasive grains cannot be processed.

  Furthermore, since the first laser beam and the second laser beam are irradiated from a direction having an angle with respect to the contact surface of the surface of the molding tool, the first laser beam and the second laser beam enter from the surface of the molding tool to the inside. That is, the truing is processed by an amount corresponding to the depth from the surface of the tool to be formed in the range that can be processed by the first laser beam. Further, the dressing is processed by an amount corresponding to the depth from the surface of the tool to be formed in the range that can be processed by the second laser beam.

The depth from the surface of the forming tool included in the Rayleigh range of the first laser light is set to be shallower than the depth from the surface of the forming tool included in the Rayleigh range of the second laser light. That is, the depth of the molding tool processed by the first laser beam is shallower than the depth of the molding tool processed by the second laser beam. In other words, the processing depth of truing with the first laser light is shallower than the processing depth of dressing with the second laser light. Therefore, in truing, the tool to be formed can be formed into a desired shape by processing the abrasive grains and the binder present on the surface side. Further, in the dressing, the abrasive particles existing on the surface side can be exposed by processing the binder present at a deep position from the surface.
Furthermore, since truing and dressing are ablation processes, there is little thermal influence on the tool to be molded. Therefore, high processing accuracy can be obtained.

(Claim 2) Preferably, the length of the Rayleigh range of the first laser light is set shorter than the length of the Rayleigh range of the second laser light, so that it is included in the Rayleigh range of the first laser light. The depth from the surface of the tool to be formed is set shallower than the depth from the surface of the tool to be included in the Rayleigh range of the second laser beam.
Thus, truing and dressing can be reliably performed by using laser beams having different lengths of the Rayleigh range.

  (Claim 3) Preferably, the condensing point of the first laser beam and the condensing point of the second laser beam are set so as to be located on the surface of the tool to be molded. When using laser beams with different lengths of the Rayleigh range, the processing depth by truing and dressing depends on the length of the Rayleigh range by positioning the focal point of each laser beam on the surface of the tool. It can be depth. Therefore, in truing and dressing, it can be reliably processed into a desired state.

  (Claim 4) Preferably, the first laser light and the second laser light are irradiated from the normal direction of the surface of the tool to be molded. Thereby, the processing depth can be easily set in truing and dressing.

  (Claim 5) Preferably, the forming tool transmits the first laser beam and the second laser beam. Then, the energy density is the highest in the vicinity of the condensing points of the first laser beam and the second laser beam, and the position in the vicinity of the condensing point of each laser beam is important for the processing depth in the tool to be formed.

  (Claim 6) Preferably, the laser molding device branches one laser beam outputted from the light source and the first laser beam and the second laser beam so as not to interfere with each other. And a laser beam branching device that simultaneously irradiates the tool with the first laser beam and the second laser beam.

  In the case of using one light source and simultaneously irradiating the first laser beam and the second laser beam, truing and dressing can be reliably performed by preventing both from interfering with each other.

It is a figure in the case of performing truing with 1st laser beam in 1st embodiment. In 1st embodiment, it is a figure in the case of performing dressing with a 2nd laser beam. It is a figure which shows the detail of the 1st laser beam of FIG. 1A. It is a figure which shows the detail of the 2nd laser beam of FIG. 1B. In 2nd embodiment, it is a figure in the case of performing truing with another 1st laser beam. In 3rd embodiment, it is a system diagram which irradiates a 1st laser beam and a 2nd laser beam from the same light source.

<First embodiment>
The laser forming apparatus of the present embodiment performs truing and dressing on the tool 10 to be formed by laser light. That is, the laser molding apparatus can irradiate the first laser beam 21 for truing (shown in FIG. 1A) and the second laser beam 31 for dressing (shown in FIG. 1B).

  The molding tool 10 is a disc-shaped grinding wheel for grinding a workpiece or a disc-shaped tourer for molding a grinding wheel. In addition, the molding tool 10 is not limited to a disk shape, and may have an arbitrary shape. As shown in FIGS. 1A and 1B, the tool 10 is provided with a plurality of abrasive grains 11, 11,... And a binder 12 that binds the plurality of abrasive grains 11, 11,. Here, truing is to form the surface of the tool 10 and dressing is to sharpen the surface of the tool 10.

  Here, the materials of the abrasive grains 11 and the binder 12 are selected so that the laser processing threshold of the abrasive grains 11 is larger than the laser processing threshold of the binder 12. The laser processing threshold is an energy density at which an object is processed by laser light. That is, when irradiating laser light having an energy density larger than the laser processing threshold value of the abrasive grains 11, the abrasive grains 11 and the binder 12 are processed. On the other hand, when irradiating laser light having an energy density smaller than the laser processing threshold value of the abrasive grains 11 and equal to or higher than the laser processing threshold value of the binder 12, the abrasive grains 11 are not processed and only the binder 12 is processed.

  The abrasive grains 11 and the binder 12 are formed of a material that transmits at least part of the laser light. That is, even when the condensing point of the laser beam is located inside the forming tool 10, the energy density near the condensing point is the highest. And the position near the condensing point of the laser beam in the tool 10 is important for the processing depth.

(Truing)
Truing is performed by the first laser beam 21 as shown in FIGS. 1A and 2A. Truing forms the surface of the tool 10 by performing laser processing on the abrasive grains 11 and the binder 12.

  The first laser beam 21 is irradiated onto the surface of the tool 10 by the first lens 22 constituting the laser forming apparatus, and the surface of the tool 10 is set as a condensing point 23. The first laser beam 21 is an ultrashort pulse laser beam capable of performing ablation processing (non-thermal processing) on the molding tool 10. For example, the first laser beam 21 is a femtosecond laser or a picosecond laser. Since truing is an ablation process, the thermal effect on the tool 10 is small. Therefore, high processing accuracy can be obtained.

Further, the length of the Rayleigh range of the first laser beam 21 is b _1. The length b ₁ of the Rayleigh range of the first laser light 21 is expressed as shown in Expression (1). The Rayleigh range is a range up to √2 times the diameter of the condensing point 23 (also referred to as a condensing beam diameter) d ₁ in the first laser light 21. In Equation (1), ω ₁ is the radius of the first laser light 21 at the focal point 23 (also referred to as the focused beam radius), λ ₁ is the wavelength, and M ² is Msquare. Further, the condensed beam diameter d ₁ is expressed as in Expression (2). In Expression (2), f ₁ is a focal length, and D ₁ is an incident beam diameter.

  Furthermore, the energy density of the condensing point 23 by the first laser light 21 is larger than the laser processing threshold of the abrasive grains 11 and the laser processing threshold of the binder 12. Accordingly, the abrasive grains 11 and the binder 12 are processed in the vicinity of the condensing point 23 of the first laser light 21 (a range included in the Rayleigh range).

And in this embodiment, the 1st laser beam 21 is irradiated from the normal line direction (perpendicular to a contact surface) of the surface of the tool 10 to be shaped. That is, the first laser beam 21 enters the inside of the tool 10 from the surface. Further, the molding tool 10 transmits at least a part of the first laser beam 21. Therefore, the processing depth t ₁ from the surface of the tool 10 to be molded by the first laser beam 21 is a depth having a correlation with the length b ₁ of the Rayleigh range of the first laser beam 21. That is, the truing is processed by an amount corresponding to the depth t ₁ from the surface of the tool 10 to be processed in the range that can be processed by the first laser beam 21. FIG. 1A illustrates that a portion of the tool 10 to be processed that is included in the Rayleigh range of the first laser beam 21 is processed.

(dressing)
Dressing is performed by the second laser beam 31 as shown in FIGS. 1B and 2B. In the dressing, the surface of the tool 10 is sharpened by laser processing only the binder 12 without processing the abrasive grains 11. That is, the dressing exposes the abrasive grains 11 from the binder 12.

  The second laser beam 31 is irradiated onto the surface of the tool 10 by the second lens 32 constituting the laser forming apparatus, and the surface of the tool 10 is set as a condensing point 33. Similar to the first laser beam 21, the second laser beam 31 is an ultrashort pulse laser beam that can be ablated (non-thermally processed) with respect to the tool 10. For example, the second laser beam 31 is a femtosecond laser or a picosecond laser. Since dressing is an ablation process, the thermal effect on the tool 10 is small. Therefore, high processing accuracy can be obtained.

Further, the length of the Rayleigh range of the second laser beam 31 is b _2. The length b ₂ of the Rayleigh range of the second laser beam 31 is expressed as in Expression (3). In Expression (3), ω ₂ is the radius of the second laser light 31 at the condensing point 33, λ ₂ is the wavelength, and M ² is Msquare. Also, the focused beam diameter _{d 2} is expressed by the equation (4). In Expression (4), f ₂ is a focal length, and D ₂ is an incident beam diameter.

  Furthermore, the energy density of the condensing point 33 by the second laser light 31 is smaller than the laser processing threshold of the abrasive grains 11 and larger than the laser processing threshold of the binder 12. Therefore, in the vicinity of the condensing point 33 of the second laser beam 31 (a range included in the Rayleigh range), the processing of the abrasive grains 11 is impossible, but the binder 12 is processed.

And in this embodiment, the 2nd laser beam 31 is irradiated from the normal line direction (perpendicular to a contact surface) of the surface of the tool 10 to be shaped. That is, the second laser beam 31 enters from the surface of the tool 10 to the inside. Further, the molding tool 10 transmits at least a part of the second laser beam 31. Therefore, the processing depth t ₂ from the surface of the tool 10 to be molded by the second laser light 31 is a depth having a correlation with the length b ₂ of the Rayleigh range of the second laser light 31. That is, the dressing is processed by an amount corresponding to the depth t ₂ from the surface of the tool 10 to be processed within the range that can be processed by the second laser beam 31. FIG. 1B illustrates that a portion of the tool 10 to be processed that is included in the Rayleigh range of the second laser beam 31 is processed.

(Contrast of truing and dressing)
Here, truing and dressing are contrasted. The energy density of the condensing point 23 by the first laser beam 21 for truing is set larger than the energy density of the condensing point 33 by the second laser beam 31 for dressing. Specifically, while the first laser beam 21 has an energy density that allows the abrasive grains 11 and the binder 12 to be processed, the second laser beam 31 cannot process the abrasive grains 11 and only the binder 12 is processed. It is possible energy density.

The length b ₁ of the Rayleigh range of the first laser beam 21 for truing is set shorter than the length b ₂ of the Rayleigh range of the second laser beam 31 for dressing. Further, the first laser beam 21 and the second laser beam 31 are irradiated from the normal direction of the surface of the tool 10 to be molded. Therefore, the depth t ₁ from the surface of the molding tool 10 included in the Rayleigh range of the first laser beam 21 is the depth t ₂ from the surface of the molding tool 10 included in the Rayleigh range of the second laser beam 31. It will be set shallower. Accordingly, the processing depth t ₁ of truing with the first laser beam 21 is shallower than the processing depth t ₂ of dressing with the second laser beam 31.

In other words, the processing depth t ₁ truing by the first laser beam 21, as shown in FIG. 1A, the only near the surface of the forming tool 10. Then, in the truing, the tool 11 can be formed into a desired shape by processing the abrasive grains 11 and the binder 12 present on the surface side of the tool 10.

On the other hand, the processing depth t ₂ of the dressing by the second laser beam 31, as shown in FIG. 1B, and reaches deeper from the surface of the forming tool 10. Therefore, as shown in FIG. 1B, in the dressing, only the binder 12 existing at a deep position from the surface of the tool 10 is processed, so that the abrasive grains 11 existing in the region where the binder 12 is processed are formed. Exposed on the surface.

As described above, truing and dressing can be reliably performed by using the first and second laser beams 21 and 31 having different Rayleigh range lengths b ₁ and b ₂ . Here, in the above, the condensing point 23 of the first laser beam 21 and the condensing point 33 of the second laser beam 31 are set so as to be located on the surface of the tool 10 to be molded. When the first and second laser beams 21 and 31 having different lengths b ₁ and b ₂ of the Rayleigh range are used, the condensing points 23 and 33 of the first and second laser beams 21 and 31 are respectively formed into tools. By being positioned on the surface of 10, the processing depths t ₁ and t ₂ by truing and dressing can be set to the depths corresponding to the lengths b ₁ and b ₂ of the Rayleigh range. Therefore, in truing and dressing, it can be reliably processed into a desired state.

Furthermore, in the present embodiment, the first laser beam 21 and the second laser beam 31 are irradiated from the normal direction of the surface of the tool 10 to be molded. In this case, the processing depth t ₁ for truing is in accordance with the Rayleigh range and energy density of the first laser beam 21. Processing depth t ₂ of the dressing, the one corresponding to the Rayleigh range and the energy density of the second laser beam 31. Accordingly, the processing depths t ₁ and t ₂ can be easily set in truing and dressing.

<Second embodiment>
In the embodiment described above, the first laser beam 21 and the second laser beam 31 are irradiated from the normal direction of the surface of the tool 10 to be molded. In the present embodiment, as shown in FIG. 3, the first laser light 41 for truing is irradiated to the surface of the tool 10 by the first lens 42, and the surface of the tool 10 is focused on the condensing point 43. To do. The first laser beam 41 is irradiated from a direction having an angle with respect to the normal line and the contact surface of the surface of the tool 10 to be molded. Here, as shown in FIG. 3, the irradiation direction of the first laser beam 41 is a direction having an angle θ (0 ° <θ <90 °) with respect to the normal line of the molding tool 10.

In this case, the depth t ₃ of the surface of the forming tool 10 included in the Rayleigh range of the first laser beam 41, of the forming tool 10 included in the Rayleigh range of the second laser beam 31 (shown in FIG. 1B) It is set shallower than the depth t ₂ from the surface. When a portion included in the Rayleigh range of the first laser beam 41 is processed in the tool 10 and the focusing point 43 of the first laser beam 41 is located on the surface of the tool 10, the processing depth The length t ₃ is as shown in Expression (5). In Expression (5), b ₃ is the length of the Rayleigh range of the first laser light 41.

That is, the truing processing depth t ₃ is in accordance with the Rayleigh range, energy density, and irradiation angle θ of the first laser light 41.

<Deformation mode>
In the first and second embodiments, the second laser beam 31 is emitted from the normal direction of the surface of the tool 10 to be molded, but from 0 ° with respect to the contact surface of the surface of the tool 10 to be molded. The angle may be greater than 90 °.

Depending on the incident angle, the length b ₁ of the Rayleigh range of the first laser beam 21 and the length b ₂ of the Rayleigh range of the second laser beam 31 can be the same. However, desired truing and dressing can be easily performed by making both different.

<Third embodiment>
Next, the laser forming apparatus 100 that irradiates the first laser beam 21 and the second laser beam 31 using the same light source will be described. As shown in FIG. 4, the laser shaping apparatus 100 includes one light source 101, a beam splitter 102 (laser beam branching device) that branches the laser light output from the light source 101 into two, and one branched laser. An ND filter 103 that reduces the amount of light; a reflector 104 that reflects the laser light that has passed through the ND filter 103; a beam width changer 105 that reduces the width of the laser light reflected by the reflector 104; and a lens 106.

  In this embodiment, the lens 106 receives the laser light transmitted through the beam splitter 102 and the laser light output from the beam width changer 105. Here, the laser beam transmitted through the beam splitter 102 and irradiated from the lens 106 is the first laser beam 21, and the laser beam output from the beam width changer 105 and irradiated from the lens 106 is the second laser beam. Light 31. The first laser beam 21 and the second laser beam 31 are as described in the above embodiment. Thus, the surface of the tool 10 can be irradiated with the first laser beam 21 and the second laser beam 31 using one light source 101.

  Here, when the first laser beam 21 and the second laser beam 31 are irradiated simultaneously, the first laser beam 21 and the second laser beam 31 are prevented from interfering with each other. If interference occurs, the desired laser beam cannot be applied to the forming tool 10. That is, by preventing interference, desired truing and dressing are possible.

The first means for preventing interference provides an optical path difference between the first laser beam 21 and the second laser beam 31 and sets the optical path difference longer than the coherent length. The second means sets the condensing point 23 of the first laser beam 21 and the condensing point 33 of the second laser beam 31 at different positions, and sets the separation distance between the condensing points 23 and 33 to be longer than the length of the Rayleigh range. the second laser beam 31 of focused beam diameter d ₂ 3 times.

  In the above-described embodiment, the laser beam output from the light source 101 is branched by the beam splitter 102, but may be branched using a diffraction grating.

10: Tool to be molded, 11: Abrasive grains, 12: Binder, 21: First laser beam, 22: First lens, 23: Condensing point of first laser beam 21, 31: Second laser beam, 32: Second lens 33: Condensing point of second laser light 31 41: First laser light 42: First lens 43: Condensing point of first laser light 41 100: Laser molding apparatus 101: Light source 102: Beam splitter 103: Filter 104: Reflector 105: Beam width changer 106: Lens d ₁ : Condensing beam diameter of the first laser beam 21 d ₂ : Collection of the second laser beam 31 Light beam diameter, θ: Irradiation angle

Claims (6)

A laser molding apparatus that performs truing and dressing with a laser beam on a tool to be molded comprising abrasive grains and a binder that binds the abrasive grains,
The abrasive laser processing threshold is greater than the binder laser processing threshold,
The laser forming apparatus includes a first laser beam for truing capable of ablating the abrasive grains and the binder, and a second laser for dressing capable of ablating the binder and not processing the abrasive grains. Irradiate with light,
The first laser light and the second laser light are irradiated from a direction having an angle with respect to a contact surface of the surface of the molding tool,
The energy density of the condensing point by the first laser light is set larger than the energy density of the condensing point by the second laser light,
The depth from the surface of the molding tool included in the Rayleigh range of the first laser light is set shallower than the depth from the surface of the molding tool included in the Rayleigh range of the second laser light.
Laser molding equipment.   By setting the length of the Rayleigh range of the first laser beam to be shorter than the length of the Rayleigh range of the second laser beam, the depth from the surface of the molding tool included in the Rayleigh range of the first laser beam is set. Is set to be shallower than the depth from the surface of the molding tool included in the Rayleigh range of the second laser light.   The laser forming apparatus according to claim 2, wherein the condensing point of the first laser light and the condensing point of the second laser light are set so as to be located on the surface of the tool to be formed.   4. The laser forming apparatus according to claim 2, wherein the first laser beam and the second laser beam are irradiated from a normal direction of a surface of the tool to be molded. 5.   The laser molding apparatus according to any one of claims 1 to 4, wherein the tool to be molded transmits the first laser light and the second laser light. The laser molding apparatus includes:
One light source,
The laser beam output from the light source is branched, and the first laser beam and the second laser beam are simultaneously applied to the forming tool so that the first laser beam and the second laser beam do not interfere with each other. A laser beam splitter for irradiating;
Comprising
The laser shaping apparatus according to any one of claims 1 to 5.

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