JP6547652B2 - Laser buildup apparatus and laser buildup method - Google Patents

Description

  The present invention relates to a laser buildup apparatus and a laser buildup method, and more particularly to a laser buildup apparatus for a valve seat and a laser buildup method.

  A laser buildup process (so-called laser cladding method) of forming a buildup layer by irradiating a laser beam while supplying metal powder is used, for example, to form a valve seat of a cylinder head.

  Patent Document 1 discloses an apparatus for observing the intensity of light generated from a molten pool with a plurality of optical sensors in laser build-up processing to determine the presence or absence of abnormality in the build-up layer.

Unexamined-Japanese-Patent No. 09-192861

  The inventor of the present invention aggregates extra metal powder (surplus powder) deposited in the forward direction of the molten pool, and semi-melts when the laser beam approaches, and balls of a certain size (ball-like metal powder aggregate) When it was absorbed into the molten pool, it was found that pores (blow holes) were generated.

  The apparatus disclosed in Patent Document 1 only observes the intensity of light generated from the molten pool, and does not have the function of detecting the above-mentioned ball-shaped metal powder aggregate that generates such holes. .

  Therefore, for example, by using the reflected light of the laser beam to be irradiated, it is possible to image how the ball-shaped metal powder aggregate is absorbed in the molten pool. However, it was not understood how the condition of the ball-shaped metal powder aggregate formed in the forward direction of the molten pool changes depending on the buildup condition. Therefore, it was not possible to optimize the buildup conditions and effectively reduce the ball-shaped metal powder aggregates.

  The present invention has been made to solve such a problem, and provides a laser overlaying device and a laser overlaying method capable of suppressing the occurrence of blow holes due to metal powder aggregates.

  A laser build-up device according to one aspect of the present invention includes a supply unit that supplies metal powder, and a laser oscillator that outputs a laser beam, and supplies the metal powder while supplying the metal powder from the supply unit. It is a laser buildup apparatus which forms a buildup layer by irradiating, Comprising: It has an imaging part which images the advancing direction forward of a molten pool, and the position of the said imaging part can be adjusted. Such a configuration can effectively reduce metal powder aggregates.

  The laser cladding method according to one aspect of the present invention is the step of forming an annular counterbore groove at the open end on the combustion chamber side of the port in the cylinder head rough profile, and supplying metal powder to the counterbore groove. A laser beam is scanned to form a build-up layer in the counterbore groove, and in the step of forming the build-up layer, the method of advancing the molten pool ahead The formed ball-shaped metal powder aggregate is imaged, and the output of the laser beam is controlled according to the imaging result of the metal powder aggregate. With such a configuration, the generation of blow holes due to metal powder aggregates can be suppressed.

  The present invention provides a laser buildup apparatus and a laser buildup method that can suppress the generation of blow holes due to metal powder aggregates.

It is the block diagram which illustrated the laser buildup apparatus which concerns on embodiment. It is sectional drawing which illustrated the nozzle of the laser buildup apparatus which concerns on embodiment. It is the figure which illustrated the nozzle and imaging part of the laser buildup apparatus which concern on embodiment. It is the perspective view which showed typically the formation method of the buildup layer by the laser buildup apparatus which concerns on embodiment. It is the flowchart figure which illustrated the laser buildup method which relates to the execution form. In the laser build-up method which concerns on embodiment, it is the graph which illustrated the relationship between the sum total of a ball | bowl and the output correction amount of a laser beam.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the attached drawings. However, the present invention is not limited to the following embodiments. Further, in order to clarify the explanation, the following description and the drawings are simplified as appropriate.

  A laser deposition apparatus according to an embodiment will be described. First, the configuration of the laser deposition apparatus will be described. FIG. 1 is a configuration diagram illustrating a laser deposition apparatus according to the embodiment. FIG. 2 is a cross-sectional view illustrating the nozzle of the laser deposition apparatus according to the embodiment. FIG. 3 is a view exemplifying a nozzle and an imaging unit of the laser buildup apparatus according to the embodiment.

  As shown in FIG. 1, the laser buildup apparatus 100 includes a supply unit 10, a nozzle 20, a laser oscillator 30, an imaging unit 40, an illumination unit 46, a display unit 47, a rotating unit 50, a pedestal 60, and a stage 61. ing. Further, as shown in FIG. 3, the laser buildup apparatus 100 also includes a laser output adjustment unit 35 and an image processing unit 41.

  As shown in FIG. 1, the pedestal portion 60 is installed on the floor surface. The pedestal portion 60 is a rectangular parallelepiped shaped member. A stage 61 is provided on the upper surface of the pedestal 60. The stage 61 fixes a work, for example, a rough cylinder head 70. The stage 61 fixes the work after appropriately setting the position and orientation of the work.

  The rotating portion 50 has a rod-like shaft 51 and a frame-like portion 52 for supporting the shaft 51. The rotating unit 50 is installed, for example, above the workpiece. The shaft 51 rotates with the central axis A2 as a rotation axis. The frame 52 does not rotate. The frame 52 supports the rotating shaft 51. The nozzle 20, the laser oscillator 30, the imaging unit 40, and the illumination unit 46 are attached to the shaft 51 via an attachment jig or the like. Therefore, the nozzle 20, the laser oscillator 30, the imaging unit 40, and the illumination unit 46 can be rotated with the central axis A2 as a rotation axis.

  The supply unit 10 is attached to the frame 52, for example. The supply unit 10 mixes the metal powder 26 introduced from the raw material inlet 11 with the carrier gas. Then, the supply unit 10 supplies the metal powder 26 to the nozzle 20 together with the carrier gas. The metal powder 26 contains, for example, copper powder. The carrier gas is, for example, an inert gas such as nitrogen or argon. The metal powder 26 mixed with the carrier gas is supplied from the supply unit 10 to the nozzle 20 via a raw material supply pipe (not shown).

  The nozzle 20 is disposed above the workpiece, and is attached to the shaft 51 via, for example, a mounting jig or the like. Therefore, the nozzle 20 can be rotated about the central axis A2. The nozzle 20 supplies metal powder 26 to the work. Further, the nozzle 20 emits the laser beam 31 output from the laser oscillator 30.

  As shown in FIG. 2, the nozzle 20 includes an inner nozzle 21, an outer nozzle 22, and a raw material supply pipe 23. The nozzle 20 has a coaxial double-pipe structure in which central axes of the inner nozzle 21 and the outer nozzle 22 coincide with each other. The laser beam 31 output from the laser oscillator 30 is emitted from the inner nozzle 21 of the nozzle 20. The optical axis A 1 of the laser beam 31 coincides with the central axis of the inner nozzle 21. From between the inner nozzle 21 and the outer nozzle 22, the carrier gas 25 and the metal powder 26 supplied via the raw material supply pipe 23 are discharged. Therefore, the central axis of the coaxial double tube structure of the nozzle 20 coincides with the optical axis A1 of the laser beam 31.

  Thus, the discharge axes of the carrier gas 25 and the metal powder 26 are coaxial with the optical axis A 1 of the laser beam 31. Note that a shield gas 24 such as an inert gas may be jetted from the inner nozzle 21 to the molten pool for the purpose of preventing the oxidation of the molten pool to be described later and protecting the exit glass of the laser beam 31. As described above, by integrating the irradiation of the laser beam 31 with the supply of the shield gas 24, the carrier gas 25, and the metal powder 26, the nozzle 20 can be made compact.

  As shown in FIG. 3, the nozzle 20 supplies the metal powder 26 to a work, for example, a processing point 32 on the rough cylinder head 70. The laser oscillator 30 outputs a laser beam 31. The output laser beam 31 irradiates the processing point 32 on the workpiece through the nozzle 20. The metal powder 26 at the processing point 32 is melted to form a molten pool 33. Thus, what the metal powder 26 fuse | melted by irradiation of the laser beam 31 is called molten pool 33. As shown in FIG. By moving the nozzle 20 in the processing direction 27 while continuing the supply of the metal powder 26 and the irradiation of the laser beam 31, the molten pool 33 is advanced in the processing direction.

  The advancing direction of the molten pool 33 is the same as the processing direction. At the rear of the advancing direction of the molten pool 33, the molten pool 33 solidifies, and a buildup layer 76 is formed. In this manner, the laser buildup apparatus 100 forms the buildup layer 76 by irradiating the laser beam 31 while supplying the metal powder 26 from the supply unit 10. The output of the laser beam 31 is controlled by a signal from the laser output adjustment unit 35.

  As shown in FIGS. 1 and 3, the imaging unit 40 is disposed above the workpiece, and is attached to, for example, the shaft 51 via a mounting jig or the like. Therefore, the imaging unit 40 can be rotated with the central axis A2 as the rotation axis. The imaging unit 40 is, for example, a high speed camera. The imaging unit 40 is provided with a positioning stage 45 with a micrometer feed screw 48. The position of the imaging unit 40 can be adjusted by, for example, the positioning stage 45. The positioning stage 45 has a handle with an XYZ-axis adjustable counter. Therefore, position adjustment can be easily performed with high accuracy and high reproducibility.

  The imaging unit 40 captures an image of the advancing direction forward of the molten pool 33. Moreover, the imaging part 40 may image the molten pool 33 and its vicinity. The imaging unit 40 can capture an arbitrary position. The imaging unit 40 transmits the captured image data to the image processing unit 41.

  The image processing unit 41 receives image data captured by the imaging unit 40 from the imaging unit 40. The image processing unit 41 performs control calculation of the laser output based on the image data received from the imaging unit 40. The control calculation includes calculation of the laser output correction amount, calculation of the output timing of the laser beam 31, and the like. The image processing unit 41 transmits the calculated result to the laser output adjustment unit 35.

  As shown in FIG. 1, the illumination unit 46 is disposed above the workpiece, and is attached to the shaft 51 via, for example, a mounting jig or the like. The illumination unit 46 is, for example, a light source that generates illumination light. The illumination unit 46 illuminates the forward direction of the molten pool 33 in the direction of travel. The lighting unit 46 may also illuminate the molten pool 33 and the vicinity of the molten pool 33. The illumination unit 46 is disposed, for example, at a position where the reflected light obtained by the illumination light reflected on the upper surface of the workpiece reaches the imaging unit 40. The imaging unit 40 and the illumination unit 46 rotate and move in synchronization with the rotational movement of the nozzle 20. The positions of the imaging unit 40 and the illumination unit 46 can be adjusted. Thereby, the object which the imaging part 40 images, and the object which the illumination part 46 illuminates can be arbitrarily set, such as the advancing direction forward direction of the molten pool 33, for example.

  The display unit 47 displays the image captured by the imaging unit 40. Further, the display unit 47 displays the result of the control calculation calculated by the image processing unit 41.

  A lighting cable 42 including a wire and the like for supplying power to the lighting unit 46 is connected to the lighting unit 46. The camera cable 43 including a wire for supplying power to the imaging unit 40, a signal line for controlling the operation of the imaging unit 40, and the like is connected to the imaging unit 40. A signal line for transmitting an image captured by the imaging unit 40 connects the imaging unit 40 and the image processing unit 41. The camera cable 44 including a signal line and the like for transmitting the image captured by the imaging unit 40 to the display unit 47 is connected to the display unit 47.

  Next, the laser deposition method will be described. For example, the laser build-up method will be described by taking the case where the build-up layer 76 is formed on the rough cylinder head 70 as an example. FIG. 4 is a perspective view schematically showing a laser buildup method according to the embodiment. As shown in FIG. 4, the cylinder head rough section 70 is a casting made of, for example, cast iron or an aluminum alloy. The cylinder head profile 70 comprises a plurality of combustion chambers 71. Each combustion chamber 71 is provided with an intake port 72 and an exhaust port 73.

  As shown in FIG. 4, first, in the rough cylinder head 70, an annular counterbore groove 75 is formed at the end of the opening 74 on the combustion chamber 71 side of the intake port 72 and the exhaust port 73 so as to surround the opening 74. Do. The counterbore 75 is formed by machining.

  After setting the position and orientation of the rough cylinder head 70 so that the center axis of the annular shape of the counterbored groove 75 coincides with the center axis A2 of the shaft portion 51 of the laser cladding device 100, the rough cylinder head is formed The material 70 is fixed to the stage 61. As a result, it is possible to form the overlaying layer 76 in the counterbored groove 75 by rotating the nozzle 20 with the central axis A2 as the rotation axis while the rough cylinder head material 70 is fixed.

  The rough cylinder head section 70 shown in FIG. 4 is for a 4-cylinder 16 valve, and each of the four combustion chambers 71 is provided with two intake ports 72 and two exhaust ports 73. As a matter of course, the numbers of the combustion chamber 71, the intake port 72 and the exhaust port 73 are not limited to the example shown in FIG.

  As shown in FIGS. 3 and 4, the nozzle 20 supplies the metal powder 26 to the counterbored groove 75. For example, the supply amount of the metal powder 26 is 0.75 [g / s]. The flow rate of the carrier gas 25 and the flow rate of the shield gas 24 are, for example, 10 [L / min] and 20 [L / min]. In addition, the nozzle 20 irradiates the laser beam 31 to the metal powder 26 supplied to the counterbore groove 75. For example, the output of the laser beam 31 is 2.8 kW. As described above, while supplying the metal powder 26, the laser beam 31 is scanned to form the buildup layer 76 in the counterbored groove 75. A molten pool 33 is formed on the surface of the buildup layer 76 facing the nozzle 20. The nozzle 20 scans the laser beam 31 along the counterbore groove 75 while moving the molten pool 33 and moves the pooler 33 along the counterbore groove 75. Specifically, the nozzle 20 is rotated with the central axis A2 as a rotation axis while the rough cylinder head 70 is fixed. A buildup layer 76 in which the molten pool 33 is solidified is sequentially formed on the mark where the molten pool 33 has moved. The processing speed is, for example, 900 [mm / min].

  FIG. 5 is a flowchart illustrating the laser deposition method according to the embodiment. As shown in step S1 of FIG. 5, the imaging unit 40 performs imaging in the forward direction of the molten pool 33. The predetermined position is imaged by adjusting and finely adjusting the imaging position of the imaging unit 40. In addition, the imaging position is fixed at a predetermined position. The imaging unit 40 transmits, to the image processing unit 41, image data on the front side in the traveling direction of the molten pool 33, which has been captured. The image processing unit 41 measures the size and number of ball-shaped metal powder aggregates present in the forward direction of the molten pool 33 from the received image, as shown in step S2. Here, the ball-shaped metal powder aggregate is referred to as a ball 34. Then, the sum of the balls 34 is defined as the sum of the number of the balls 34 multiplied by the weighting factor for each size of the balls 34. For example, the sum of the balls 34 can be obtained by the following equation (1).

  X (sum total) = C1 × N1 + C2 × N2 + C3 × N3 + (1)

  Here, Ci is a weight coefficient according to the size of the ball 34, and the coefficient is larger as the ball 34 is larger. Ni is the number of balls 34.

  FIG. 6 is a graph illustrating the relationship between the sum of the balls 34 and the output correction amount of the laser beam in the laser build-up method according to the embodiment. As shown in FIG. 6, the relationship between the total sum of the balls 34 present in the forward direction of the molten pool 33 and the output correction amount of the laser beam 31 is obtained in advance by test processing. The output correction amount of the laser beam 31 includes the output of the laser beam 31 which can reduce the number of holes (blow holes) generated inside the buildup layer 76 due to the presence of the balls 34, and the set output of the laser beam 31. The difference between Therefore, when the sum total of arbitrary balls 34 is present in the forward direction of the molten pool 33, the output correction amount calculated from FIG. 6 is added to the setting output of the laser beam 31. Thereby, the output of the laser beam can be changed to an output capable of reducing the number of holes (blow holes).

  Next, as shown in step S3, the image processing unit 41 performs control calculation. The image processing unit 41 determines the quality of the buildup layer 76 being formed, for example, from the total sum of the balls 34 in the image received from the imaging unit 40. For example, the determination is made by setting a threshold or the like of the sum of the balls 34. Then, when it is necessary to improve the quality from the determination result, the output correction amount of the laser beam 31 is calculated based on FIG. In addition, the image processing unit 41 calculates the timing of changing the laser output based on the distance between the imaging position in the forward direction of the molten pool 33 and the irradiation position of the laser beam 31 and the processing speed. Then, the image processing unit 41 transmits the calculated output correction amount and timing to the laser output adjustment unit 35.

  Next, as shown in step S4, the laser output adjustment unit 35 receives the output correction amount and the timing calculated by the image processing unit 41. The laser output adjustment unit 35 controls the laser oscillator 30 so as to change the output of the laser beam 31 by the received output correction amount at the received timing. Thus, the laser oscillator 30 changes the output of the laser beam 31 at the timing calculated by the image processing unit 41. A buildup layer 76 is formed over the entire circumference of the counterbored groove 75 by using feedback of such imaging results.

  According to the present embodiment, the imaging unit 40 for imaging the forward direction of the molten pool 33 is provided, and the position of the imaging unit 40 can be adjusted. Therefore, it can be known how the condition of the ball 34 (ball-shaped metal powder aggregate) formed in the forward direction of the molten pool 33 changes according to the buildup condition. As a result, the buildup conditions can be optimized to effectively reduce the balls 34 (ball-like metal powder aggregates).

  Further, the imaging unit 40 is provided with a position adjustment jig such as the positioning stage 45 etc., and high accuracy is given to the molten pool 33 and an arbitrary position in the vicinity thereof in addition to the forward direction of the molten pool 33. Imaging can be performed simply. Therefore, the quality determination of the built-up layer 76 can be performed by observation of the spot. Then, the imaging result and the quality determination can be fed back to the buildup condition, and the buildup condition can be rapidly optimized. Therefore, the quality of the buildup layer 75 can be improved, and the defect rate of the buildup layer 76 can be reduced.

  Furthermore, since the adjustment of the imaging position can be performed with high accuracy in a short time, the time and cost for optimizing the buildup conditions can be significantly reduced. For example, it is not necessary to create a jig for fixing the imaging unit 40 at the optimum position as in the conventional example. Further, for example, it is not necessary to fix the imaging unit 40 with a multi-joint magnet stand as in the prior art. In this conventional method, the current position can not be determined quantitatively, and even in the case of position adjustment, it is difficult to fit in the desired direction in the desired direction on each axis of the articulated magnet stand. Further, in such a stand, even if the imaging position is determined, it is difficult to reproduce the imaging position once it is disassembled.

  On the other hand, in the present embodiment, the positioning stage 45 is used for position adjustment of the imaging unit 40. Since the positioning stage 45 has a handle with an XYZ-axis adjustable counter, it is possible to perform position adjustment with high accuracy and high reproducibility.

  Further, according to the present embodiment, when forming the buildup layer 76, the ball-shaped metal powder aggregate formed in the forward direction of the molten pool 33 is imaged, and the imaging result of the metal powder aggregate is obtained. The output of the laser beam 31 is controlled. With such a configuration, the generation of blow holes due to metal powder aggregates can be suppressed.

  Although the embodiments of the laser build-up apparatus and the laser build-up method according to the present invention have been described above, the present invention is not limited to the above configuration, and modifications can be made without departing from the technical concept of the present invention.

  For example, the supply amount of the metal powder 26, the flow rate of the shield gas, the flow rate of the carrier gas, the output of the laser beam and the processing speed are not limited to those described above, and those under optimized overlay conditions may be used. . Further, the work is not limited to the rough cylinder head 70, but may be another member on which the overlay 75 is formed.

DESCRIPTION OF REFERENCE NUMERALS 10 supply unit 20 nozzle 24 shield gas 25 carrier gas 26 metal powder 27 processing direction 30 laser oscillator 31 laser beam 32 processing point 33 molten pool 34 ball 35 laser output adjustment unit 40 imaging unit 41 image processing unit 42 illumination cable 43 for camera Cable 44 Camera cable 45 Positioning stage 46 Lighting unit 47 Display unit 48 Micrometer feed screw 50 Rotating unit 51 Shaft unit 52 Frame-like unit 60 Base unit 61 Stage 70 Cylinder head coarse-shaped member 71 Combustion chamber 72 Intake port 73 Exhaust port 74 Opening 75 Counterbore 76 Filled Layer 100 Laser Filler

Claims (2)

A supply unit for supplying metal powder,
And a laser oscillator for outputting a laser beam,
A laser buildup apparatus that forms a buildup layer by irradiating the laser beam while supplying the metal powder from the supply unit.
An imaging unit for imaging the advancing direction forward of the molten pool ;
An image processing unit that controls the output of the laser beam based on the image data received from the imaging unit;
Further comprising a,
Ri adjustable der position of the imaging unit;
The imaging unit images a ball-shaped metal powder aggregate formed in the forward direction of the molten pool;
The image processing unit controls the output of the laser beam according to the imaging result of the metal powder aggregate.
Laser buildup equipment. Forming an annular counterbore at a combustion chamber side open end of the port in the cylinder head rough member;
And supplying a metal powder to the counterbored groove while scanning a laser beam to form a cladding layer on the counterbored groove.
In the step of forming the buildup layer,
Imaging a ball-shaped metal powder aggregate formed in the forward direction of the molten pool, and controlling the output of the laser beam according to the imaging result of the metal powder aggregate;
Laser buildup method.

Images