JPH0860233A - Laser beam quenching apparatus and its quenching method - Google Patents

Abstract

PURPOSE: To keep the roundness of a cylindrical work to a prescribed range, to enable a laser beam quenching to the work even if the inner diameter of the work is small and to prevent the lowering the surface temp. of the work. CONSTITUTION: The whole peripheral chuck 17 holding by pressing the outer peripheral surface of the cylindrical work W is constituted with three chuck claws 19. Each chuck claw 19 is the one bringing the holding surface 27 which contacts with the work W, into contact with the part of 1/3 in the whole periphery of the work W and the contacting condition with the whole periphery of the work W is held by using three chuck claws 19. Further, in each chuck claw 19, a beam damper part 29 for receiving the laser beam 31 reflected with the inner peripheral surface of the work W is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser quenching apparatus and a quenching method for quenching a cylindrical work whose outer peripheral surface is pressed and held by irradiating it with laser light.

[0002]

2. Description of the Related Art A laser hardening method for hardening the inner peripheral surface of a cylindrical work with laser light is described in, for example, Japanese Patent Laid-Open No. 59-76816. FIG.
FIG. 3 is a side view of the laser hardening apparatus showing a state where the laser beam 1 is applied to the cylindrical work W as described above.

The cylindrical work W is held by a three-jaw chuck 5 provided on the upper end of the chuck body 3.
In the three-jaw chuck 5, three chuck claws 9 fixed to the block 7 are movable on the base 6 toward the center of the work W together with the block 7, and each chuck claw 9 is
As shown in FIG. 9, the holding surface 9a that contacts the outer peripheral surface of the work W is formed in an arc surface so as to be in close contact with the outer peripheral surface of the work W.

The laser beam 1 is oscillated by a laser oscillator (not shown) and then emitted from the inside of an optical unit 11 in which a condensing optical system is housed. When the chuck body 3 rotates, the laser beam 1 is applied to the inner peripheral surface of the rotating work W. Is irradiated. Inside the work W, a beam damper 13 for receiving the reflected light is arranged in order to prevent the laser light reflected on the inner peripheral surface of the work W from irradiating a member on the apparatus side such as the chuck body 3 with the reflected light. The beam damper 13 is attached to the tip of a support member 15 extending downward from the optical unit 11.

[0005]

However, such a conventional laser hardening apparatus has the following problems.

(1) Since quenching is performed with the three-jaw chuck 5 fixing the outer periphery of the work W at three locations, the work W has uneven thermal expansion over the entire circumference due to heating during quenching. When the inner diameter is 60 mm, the roundness before and after quenching deteriorates by about 30 μm.

(2) Since the beam damper 13 for receiving the reflected light of the laser light 1 needs to be inserted inside the work W,
In the case of a small work having an inner diameter of less than 60 mm, for example, even if the size of the beam damper 13 is reduced in consideration of the capacity of the beam damper 13, the beam damper 13 cannot be inserted into the work W and quenching cannot be performed.

(3) FIG. 10 shows the relationship between the surface temperature of the workpiece irradiated with the laser beam and the quench hardening width.
Here, for example, a hardness HV of 270 or more and a quench hardening width of 4.2 mm or more are required values, and the lower limit of the workable surface temperature of quenching is 700 ° C. The upper limit is 900 ° C
However, when this temperature is exceeded, there is no problem with the quench hardening width, but surface melting begins and the quality fails.

FIG. 11 shows the relationship between the quench hardening width (mm) and the quench hardening depth (mm) when the S20C material is quenched and cut and corroded. In the figure, the hardness of the area A located on the work surface side is HV400 or more, and B
The hardness of the area is HV300-400.

According to FIG. 11 above, the quench hardening depth changes corresponding to the quench hardening width, and according to FIG. 10 the quench hardening width changes depending on the surface temperature of the work. Therefore, the surface temperature of the work is the quench hardening width. And it will affect the quench hardening depth.

Here, the work W and the chuck claw 9 described above are used.
Since they are in metal contact with each other, the heat of the work W is radiated to the chuck claws 9 during laser hardening, and the surface temperature of the work W is lowered. When the surface temperature is lower than 700 ° C., as shown in FIG. 10, the quench hardening width does not reach the required value (4.2 mm or more), and there is a problem that stable quenching cannot be performed. . Therefore, in this case, the rotation speed of the work W must be reduced until the surface temperature of the work W reaches a predetermined value,
In addition to destabilizing the quenching quality, this leads to wasteful energy consumption and an increase in manufacturing cost due to a long quenching cycle time.

Therefore, according to the present invention, it is possible to maintain the circularity of a cylindrical work piece as desired, to enable laser hardening of the work piece even if the work piece has a small inner diameter, and to prevent the surface temperature of the work piece from decreasing. It is an object.

[0013]

In order to achieve the above object, the present invention firstly provides a laser beam in a state where a cylindrical work is pressed and held by a work holder that contacts the outer peripheral surface of the work. In a laser hardening device that is irradiated with
The work holder is composed of a plurality of moving bodies that can move toward and away from the center of the work with respect to the base, and a contact surface for the outer peripheral surface of the work by the plurality of moving bodies is It is configured to contact the entire outer circumferential surface of the work in the circumferential direction.

Secondly, in a laser hardening apparatus in which a cylindrical work is pressed and held by a work holder contacting its outer peripheral surface, the work holder is provided with the laser beam. A beam damper unit for receiving the reflected light of the laser light applied to the work is provided.

Thirdly, in the first structure, the work holder composed of a movable body is provided with a beam damper section for receiving the reflected light of the laser beam applied to the work.

Fourth, in the first or third configuration,
Three work holders composed of moving bodies are arranged at equal intervals in the circumferential direction, and the contact surface of each work holder with the work is an arc surface corresponding to approximately 1/3 of the entire circumference of the work. ing.

Fifth, in the second or third configuration,
The beam damper section receives the laser light that is incident from one opening of the cylindrical work and reflected by the inner peripheral surface of the work, and is configured to cover the peripheral edge of the other opening of the cylindrical work.

Sixthly, in the fifth configuration, an auxiliary beam damper is provided on the side opposite to the side on which the laser light is incident on the beam damper section, at a position facing the opening surrounded by the tip peripheral edge of the beam damper section. There is.

Seventh, in a laser hardening method in which a cylindrical work is pressed and held by a work holder which contacts the outer peripheral surface thereof, the cylindrical work is irradiated with laser light. With a plurality of moving bodies moving toward the center, the contact surface of the tip is brought into contact with the entire circumference of the outer peripheral surface of the work to press and hold it, and in this state, the work is irradiated with laser light, which is a quenching method. .

Eighth, in a laser hardening method in which a cylindrical work is pressed and held by a work holder contacting its outer peripheral surface, the work is held by the work holder in a laser hardening method. In this quenching method, a cylindrical work is irradiated with laser light, and the reflected light of the irradiated laser light is applied to a beam damper portion provided on the work holder.

Ninth, the seventh method is a quenching method in which a laser beam reflected by a work is applied to a beam damper portion provided on a work holder composed of a moving body.

[0022]

According to the first, third, seventh, and ninth methods, the work holding body is composed of a plurality of moving bodies that can move toward and away from the center of the cylindrical work. Holds the work in contact with the entire outer circumferential surface of the work in the circumferential direction, so that deformation of the work is suppressed and its roundness is maintained as desired.

According to the second, third, eighth, and ninth methods, since the reflected light of the laser beam applied to the work is applied to the beam damper section of the work holder, the work holder is It is heated by this reflected light, and the temperature difference between the work and the work is reduced, and the decrease in the surface temperature of the work is suppressed.

According to the fourth structure, almost 1 of the entire circumference of the work is obtained.
By using three work holders each having an arcuate surface corresponding to the outer peripheral surface of / 3, the work holder holds the work in a state of being in contact with the entire outer circumferential surface of the work in the circumferential direction.

According to the fifth structure, the laser light incident from one opening of the cylindrical work is reflected by the inner peripheral surface of the work, and the reflected light is emitted from the other opening and is directed to the beam damper. Is irradiated.

According to the sixth configuration, when the reflected light of the laser light reflected on the inner peripheral surface of the work advances further ahead of the beam damper, the auxiliary beam damper receives the advanced laser light.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of a laser hardening apparatus showing an embodiment of the present invention. Cylindrical work W here
Are held by an all-peripheral chuck 17, which is a work holder. The full circumference chuck 17 has three chuck claws 19
Are detachably fixed on the block 21, respectively, and the chuck claw 19 and the block 21 form a pair and can move on the base 22 in a direction of approaching and separating from the center of the work W. It consists of a moving body. The omnidirectional chuck 17 is composed of, for example, an air chuck driven by air pressure.

The chuck claw 19 is one chuck claw 19
As shown in FIG. 2 which is a plan view of FIG.
It has a fixing portion 23 provided with a and fixed to the block 21, and a holding portion 25 that is formed perpendicular to the fixing portion 23 and holds the work W. The holding portion 25 has a fan shape of 120 degrees as a whole, and the holding surface 27 as a contact surface that comes into contact with the outer peripheral surface of the work W is formed into a concave arc surface similar to the outer peripheral surface of the work W. . That is, by using three chuck claws 19 having the holding surface 27, the full-circumferential chuck 17 is in contact with the outer circumferential surface of the work W in the circumferential direction.

Each of the three chuck claws 19 is integrally formed with a beam damper portion 29 projecting toward the center of the work W at the end of the holding surface 27 on the side of the fixed portion 23. The tip 29a of the beam damper portion 29 is formed in a circular arc surface concentric with the holding surface 27, and the tip 29a of the three beam damper portions 29 is held in a state where the workpiece W is held by the three chuck claws 19.
A circular opening 30 is formed by the peripheral edge of the. The beam damper unit 29 as described above receives the reflected light of the laser light 31 on the inner peripheral surface of the work W, and the laser light 31.
Is oscillated from a laser oscillator (not shown) and then emitted downward from the inside of the optical unit 33 in which the condensing optical system is housed in FIG.

The base 22 to which the entire circumference chuck jaws 17 are attached is fixed on the chuck body 35, and the beam damper is provided in the space 36 formed in the center of the base 22 on the upper end surface 35a of the chuck body 35. An auxiliary beam damper 37 for receiving laser light leaking downward from the portion 29 is detachably installed.

The chuck body 35 has a lower rotating portion 3
9 is rotatable with respect to the fixed part 41, and the work W is also rotated by the rotation of the chuck body 35 accompanying the rotation of the rotating part 39. During the rotation of the work W, the laser light 31 is directed to the inner peripheral surface of the work W. Is irradiated.

The fixed portion 41 is fixed to a support base 43, and the support base 43 is rotatable about a central axis 49 of a bracket 47 installed on the table 45, and this rotation position is set to a predetermined value. By doing so, it becomes possible to incline the work W, and thereby to irradiate the inner peripheral surface of the work W with the laser light 31 which is irradiated downward in the vertical direction.

Next, the operation of the laser hardening apparatus as described above will be described.

The work W is set on the entire circumference chuck 17,
In this state, the three chuck claws 19 are moved together with the block 21 toward the center of the work W with respect to the base 22, so that the work W is held by the entire circumference chuck 17. The support base 43 is rotated about the central axis 49 of the bracket 47 to set a predetermined angle, and in this state, the chuck body 35 is rotated at a predetermined speed with respect to the fixed portion 41 via the rotating portion 39.

As the chuck body 35 rotates, the work W held by the full-circumferential chuck 17 also rotates, and the inner peripheral surface of the work W in this rotating state is irradiated with the laser light 31 from inside the optical unit 33 above. As a result, the quenching process is performed along the circumferential direction of the inner peripheral surface of the work W.

Here, in the full-circumferential chuck 17 that holds the cylindrical work W, the holding surface 27 of each chuck claw 19 makes contact with one-third of the entire outer peripheral surface of the work W. By using three chuck claws 19, the work W can be held in contact with the entire outer peripheral surface of the work W. As a result, the expansion of the work W heated by the quenching uniformly goes inward all around, and the roundness of the work W after the quenching treatment is improved. FIG. 3 shows the margin of deterioration of the roundness of the cylindrical work W before and after quenching for the samples of three works W (inner diameter 60 mm). 30 μm)
You can see that it has been improved.

Laser light 3 irradiated on the inner peripheral surface of the work W
1 is reflected here, and the beam damper portion 2 of the chuck claw 19
Reach 9 above. The beam damper unit 29 receives the reflected light of the laser light 31, and its temperature rises.
The temperature of the holding portion 25 that comes into contact with the
The overall temperature also rises. As a result, the temperature difference between the work W heated by the laser beam 31 and the full-circumferential chuck 17 becomes small, and the heat radiation of the work W to the full-circumferential chuck 17 is suppressed. As a result, a decrease in the surface temperature of the work W irradiated with the laser beam 31 is prevented, the quench hardening width is maintained as desired, and stable quenching processing can be performed.

FIG. 4 shows the relationship between the surface temperature of the work W when the work W is quenched and the rotation speed (m / min) at the time of quenching the work W in this embodiment (solid line) and the conventional example. (Dotted line) is shown for comparison. The laser power here is 4.8 kw. According to this, when the quenchable temperature range is 700 ° C. to 900 ° C., the rotation speed of the work W is increased to about 1.4 times that of the conventional one. As a result, in addition to stabilizing the quenching quality, it is possible to save energy and reduce the manufacturing cost by shortening the quenching cycle time.

When the work W is continuously quenched,
After a certain number of times, the heat input amount and the heat radiation amount for the work W become equal, and the work W reaches the equilibrium temperature. The rotation speed of the work W is adjusted so that the temperature at this time falls within a temperature range in which quenching is possible. FIG. 5 shows the temperature a of the chuck claw 19 and the laser light 3 of the work W with respect to the number of times of quenching.
1 is the surface temperature b (4 types are shown according to the 4 types of rotation speeds of the workpiece W), and the surface temperature b of the workpiece W is changed by the rotation speed of the workpiece W. I understand. Therefore, by appropriately changing the rotation speed of the work W according to the number of times of quenching, the surface temperature b of the work W can be set to a quenchable temperature range (700 to 900 ° C.).
It is possible to put in.

FIG. 6 shows the temperature a of the chuck jaws 19, the surface temperature b of the work W, and the temperature c outside the work W. According to this, in the conventional example according to (1), since the temperature a of the chuck jaws 19 is low, the work surface temperature b does not reach the quenchable temperature range of 700 to 900 ° C., but the present example according to (2) Then the temperature a of the chuck claw 19
Is around 200 ° C., which is almost equal to the outer temperature c of the work W, and it can be seen that the work surface temperature b reaches the quenchable range.

Here, as shown by (3) in FIG. 6, when the temperature a of the chuck claw 19 rises too much,
Since the surface temperature b of the work W also exceeds 900 ° C,
For example, as shown in FIG. 7, the chuck claw 19 is cooled by using the air nozzle 51.

In addition, the beam damper 29 is attached to the chuck claw 1.
Since it is provided in No. 9, it is not necessary to insert the beam damper portion into the cylindrical work W from the optical unit 33 side as in the conventional case, and therefore laser hardening is possible even for a work having an inner diameter as small as 60 mm or less. .

When the laser light 31 emitted toward the inner peripheral surface of the work W leaks further below the beam damper portion 29, the leaked laser light is the auxiliary beam damper 3.
7, the irradiation of the laser beam on the chuck body 35 side is avoided.

In the above embodiment, the beam damper unit 2
9 is integrated with the chuck claws 19, the beam damper part 29 is provided for the chuck claws 19 made of casting.
The copper may be detachable with a screw or the like.

[0046]

As described above, according to the present invention, the work holder movable in the direction toward and away from the center of the cylindrical work is provided on the outer peripheral surface of the work in the entire circumferential direction. Therefore, even if laser hardening is performed in this state, the deformation of the work due to thermal expansion is suppressed, and the roundness can be maintained as desired.

Further, since the work holder for pressing and holding the outer peripheral surface of the cylindrical work is provided with the beam damper portion for receiving the reflected light of the laser light applied to the work, the beam damper portion receives the reflected light of the laser light. That raises the temperature,
Along with this, the temperature difference between the work holder and the work, which rises in temperature, is reduced, and the decrease in the surface temperature of the work can be suppressed, and stable quenching processing can be performed.

When the laser light reflected on the inner peripheral surface of the work travels further forward than the beam damper, the auxiliary beam damper receives it, so that the leakage of the laser light can be prevented.

[Brief description of drawings]

FIG. 1 is a side view of a laser hardening apparatus showing an embodiment of the present invention.

FIG. 2 is an enlarged plan view of chuck jaws of the laser hardening device of FIG.

FIG. 3 is an explanatory diagram showing changes in circularity before and after quenching of a cylindrical work by the laser quenching apparatus of FIG.

FIG. 4 is an explanatory diagram showing a relationship between a rotation speed of a work and a surface temperature of the work.

FIG. 5 is an explanatory diagram showing a surface temperature of a work and a chuck temperature during continuous hardening.

FIG. 6 is an explanatory view showing the surface temperature and the outside temperature of the work and the chuck temperature at the time of quenching in comparison with the conventional one.

FIG. 7 is a cross-sectional view of essential parts showing an example in which a cooling mechanism for a chuck claw is provided.

FIG. 8 is a side view of a laser hardening apparatus showing a conventional example.

9 is an enlarged plan view of chuck jaws of the laser hardening apparatus of FIG. 1. FIG.

FIG. 10 is an explanatory diagram showing a relationship between a surface temperature of a work and a quench hardening width.

FIG. 11 is an explanatory diagram showing hardness with respect to a quench hardening width and a quench hardening depth on the surface of the work.

[Explanation of symbols]

 W Work 17 All-round chuck (work holder) 19 Chuck claw 22 Base 27 Holding surface (contact surface) 29 Beam damper section 30 Opening section 31 Laser light 37 Auxiliary beam damper

Claims (9)

[Claims] 1. A laser hardening apparatus in which a cylindrical work is pressed and held by a work holder that contacts an outer peripheral surface of the work, and the work holder is mounted on a base. On the other hand, it is composed of a plurality of moving bodies that can move toward and away from the center of the work, and the contact surface of the plurality of moving bodies with respect to the outer peripheral surface of the work is the entire circumference in the circumferential direction of the outer peripheral surface of the work. A laser hardening apparatus characterized in that it is in contact with a laser. 2. A laser hardening apparatus in which a cylindrical work is pressed and held by a work holder that is in contact with the outer peripheral surface of the work, and the work is held by the work holder. A laser hardening device, comprising a beam damper part for receiving the reflected light of the emitted laser light. 3. The laser hardening apparatus according to claim 1, wherein the work holding member composed of a moving body is provided with a beam damper section for receiving the reflected light of the laser light applied to the work. 4. The work holders composed of moving bodies are arranged at three equal intervals in the circumferential direction, and the contact surface of each work holder with respect to the work corresponds to a portion of about ⅓ of the entire circumference of the work. 2. The structure according to claim 1, wherein the structure is an arc surface.
Alternatively, the laser hardening device according to the item 3. 5. The beam damper section receives laser light that is incident from one opening of a cylindrical work and reflected by the inner peripheral surface of the work, and covers the peripheral edge of the other opening of the cylindrical work. 2. The method according to claim 2 or 3, wherein
The described laser quenching device. 6. The auxiliary beam damper is provided on the side opposite to the side where the laser light is incident on the beam damper section and at a position facing the opening surrounded by the tip peripheral edge of the beam damper section. Laser hardening equipment. 7. In a laser hardening method in which a cylindrical work is pressed and held by a work holder that is in contact with the outer peripheral surface of the work, the cylindrical work is centered in the laser hardening method. A plurality of moving bodies that move toward the section are brought into contact with the contact surface of the tip over the entire circumference of the outer peripheral surface of the work to press and hold it, and in this state, the work is irradiated with laser light. -The hardening method. 8. A laser-irradiated laser hardening method in which a cylindrical work is pressed and held by a work holder that contacts the outer peripheral surface of the work, and the cylinder is held by the work holder. A laser quenching method, comprising: irradiating a laser beam onto a work piece, and irradiating the beam damper portion provided on the workpiece holder with reflected light of the irradiated laser light beam. 9. The laser hardening method according to claim 7, wherein the laser beam reflected by the work is applied to a beam damper portion provided on a work holder composed of a moving body.