JP6877297B2 - Laser processing equipment, cylinder block manufacturing method, and cylinder block - Google Patents

Description

The present invention relates to a laser machining apparatus for forming a linear groove on the surface of a work piece, a method for manufacturing a cylinder block, and a cylinder block.

Conventionally, the surface of a material is irradiated with laser light to form a large number of independent fine dents, and the lubricating oil and fat are retained in the dents to create a smooth surface with minimal surface roughness, which is used with the mating member. A technique for obtaining good sliding characteristics is known.

For example, in the device for forming a fine periodic groove on the inner peripheral surface (cylinder surface) of a cylinder block according to Patent Document 1, a femtosecond laser oscillator that oscillates a femtosecond laser, a laser processing head, and a cylinder block are gripped. It also has a work control table that moves in three-dimensional directions (X-axis, Y-axis, and Z-axis). Different homogenizers are arranged on the laser machining head according to the machining type. When machining a fine periodic groove on the cylinder surface, a periodic groove homogenizer is used. The periodic groove homogenizer generates a single laser beam with improved energy efficiency by shaping the energy distribution of the incident laser beam into a rectangular shape. By irradiating the laser beam while moving the cylinder block in the three-dimensional direction, a fine periodic groove is formed on the cylinder surface. Further, when dimples are machined on the cylinder surface, a dimple machining homogenizer is used. The dimple processing homogenizer generates a large number of laser beams by dividing the energy distribution of the incident laser beams into a plurality of spots having high energy densities. By irradiating the cylinder surface with this large number of laser beams, dimples are formed on the cylinder surface.

In the laser processing apparatus according to Patent Document 1, in groove processing using a periodic groove homogenizer, a highly accurate groove can be formed by accurately controlling the movement of the work control table, but one laser Since one groove is machined with light, there is a problem that the processing time becomes long. Even if the work control table is moved to form the dimples linearly when the dimples are formed by the dimple processing homogenizer, the groove width is too large and the grooves are randomly overlapped with each other. The problem arises that the intended sliding characteristics cannot be obtained.

Japanese Unexamined Patent Publication No. 2008-200700

In view of the above-mentioned circumstances, there is a demand for a laser machining apparatus capable of forming a plurality of grooves extending at appropriate intervals on the surface of a workpiece in a short machining time.

The laser processing apparatus according to the present invention, which forms a plurality of linear adjacent grooves on the inner wall surface of the cylinder of the cylinder block of the engine to be processed, independently separates a plurality of branched laser beams branched from one laser beam. The cylinder block so that the inner wall surface of the cylinder is scanned by the irradiation probe having an irradiation port for irradiating the same inner wall surface of the cylinder as a group of branched laser light heading in the same direction and the irradiation point of the branched laser light. One or more of the branched laser beams form one of the plurality of grooves, and at the same time, the other branched laser beams form another one of the plurality of grooves.

According to this configuration, each of the plurality of branched laser beams independently directs to the workpiece and irradiates the surface of the workpiece at a predetermined irradiation point. As a result, dents are formed at each irradiation point on the surface of the workpiece. At that time, a relative movement occurs between the workpiece and the branched laser beam, and the recess formed by the branched laser beam becomes a linear groove due to the relative movement. At that time, the distribution of the branched laser light is adjusted so that the plurality of branched laser beams do not form one groove in common, but form at least a plurality of grooves. As a result, in this laser processing apparatus, a plurality of grooves are formed at the same time by scanning the branched laser beam branched from one laser beam, so that fine grooves that produce good sliding characteristics can be formed in a short time. Achieved.

In one of the preferred embodiments of the present invention, the irradiation points of the branched laser beam in the branched laser beam group are configured to be located on a plurality of straight lines parallel to each other. In this configuration, only by making the relative movement of the branched laser beam and the workpiece a linear motion, linear grooves parallel to each other are formed by the plurality of branched laser beams. This configuration is suitable when the formation of linear grooves parallel to each other is desired. The straight line here is used in a broad sense, and includes a deemed straight line (shortest line, etc.) on a curved surface.

In order to form many grooves at the same time, a large number of branched laser beams are required. Further, in order to compactly distribute a large number of branched laser beams, it is preferable to arrange a large number of branched laser beams on a surface (two-dimensional arrangement) instead of arranging them on a line. Further, in order to form a large number of grooves with a uniform distribution, it is preferable to arrange the irradiation points of a large number of branched laser beams to form lattice points. Therefore, in one of the preferred embodiments of the present invention, the irradiation points of the branched laser beams in the branched laser beam group are configured to be located on a plurality of straight lines intersecting each other. Further, since the irradiation points of a large number of branched laser beams form a square lattice point, the distribution of the formed grooves becomes uniform. Therefore, it is also one of the preferred embodiments that the intervals between the irradiation points of the branched laser beam in the branched laser beam group are the same.

In one of the preferred embodiments of the present invention, at least two or more of the branched laser beams in the branched laser beam group are configured to form the same groove. In this configuration, the groove formed by the plurality of branched laser beams can have a larger cross section because the energy given is doubled. This configuration is suitable when it is desired to form a larger groove cross section even if the number of grooves formed at the same time is reduced. On the contrary, when it is desired to form as many grooves as possible at the same time, the branched laser beams in the branched laser beam group are configured to form different grooves. In this configuration, since one branched laser beam is allocated to one groove formation, as many grooves as the number of branched laser beams are formed at the same time, and a large number of grooves can be formed in a short time.

Techniques for improving sliding properties by forming fine depressions on the surface, when applied to the inner wall of an engine cylinder, yield good results. In the present invention, since the groove to be formed on the entire inner wall surface of the cylinder is formed by a plurality of branched lasers simultaneously irradiated, this processing time is significantly shortened as compared with processing by a single light beam. To.
Further, the method for manufacturing a cylinder block of the present invention is as follows.
This is a method of forming a plurality of linear adjacent grooves on the inner wall surface of the cylinder of the cylinder block of the engine. A group of branched laser beams in which a plurality of branched laser beams branched from one laser beam are independently directed in the same direction. The step of irradiating the same inner wall surface of the cylinder and one or more of the branched laser beams form one of the plurality of grooves, and at the same time, the other branched laser beam is formed by the other one of the plurality of grooves. The step of scanning the inner wall surface of the cylinder with the irradiation point of the branched laser beam is provided so as to form the above.
Further, the cylinder block of the present invention, Ru includes an inner wall having grooves branching laser light branching the laser beam from the laser light source into a plurality of branch laser beam is formed by being irradiated.

It is explanatory drawing which shows typically the structural example of the laser processing apparatus by this invention. It is explanatory drawing which shows typically the state at the time of the start of processing of simultaneous multiple groove processing by a plurality of branched laser beams branched by a diffractive optical element. It is explanatory drawing which shows typically the state in the process of processing of simultaneous multiple groove processing by the plurality of branched laser beams branched by a diffractive optical element. It is a front view which shows the groove formed in the inner wall surface of a cylinder. It is a perspective view which shows the groove formed in the inner wall surface of a cylinder. It is an enlarged view of the groove group which shows the experimental result of grooving. It is a figure which graphed the cross-sectional state of a groove group which shows the experimental result of grooving.

Hereinafter, an example in which the laser processing apparatus according to the present invention is applied to the groove processing for forming a large number of grooves on the inner wall surface of the cylinder block of the engine will be described. FIG. 1 schematically shows the configuration of a laser processing apparatus in such an application example. Only a small part of the cylinder block 1 which is a work piece is shown.

The laser processing apparatus includes a laser apparatus main body 2, an irradiation probe 3, a processing table 4, a scanning mechanism 5, and a control controller 6. The laser apparatus main body 2 includes a laser light source 20 that generates an ultrashort pulse laser that is a high-energy laser beam, and a primary laser optical system that includes a mirror 21. The irradiation probe 3 is optically connected to the laser apparatus main body 2, and has a built-in secondary laser optical system including an objective lens unit 31, a diffractive optical element 32, and a mirror 33. The laser light sent from the laser light source 20 is focused by the objective lens unit 31 and incident on the diffractive optical element 32. The diffractive optical element 32 has a function of branching the incident laser light into a plurality of branched laser beams, which are independently directed in substantially the same direction. The plurality of branched laser beams are directed by the mirror 33 as a group of branched laser beams having a predetermined cross-sectional shape, and irradiate the inner wall surface 1a of the cylinder of the cylinder block 1 substantially vertically. That is, as many irradiation points as the number of branched laser beams are generated on the inner wall surface 1a of the cylinder. As the distribution pattern of the irradiation points on the inner wall surface 1a of the cylinder or the virtual plane, a pattern located on a plurality of straight lines parallel to each other, a pattern located on a plurality of straight lines intersecting (including orthogonalities) with each other, and the like are used. The diffractive optical element 32 is removable, and the number of branched laser beams and the distributed shape thereof can be changed by exchanging the diffractive optical element 32.

The objective lens unit 31, the diffractive optical element 32, and the mirror 33 are housed in the housing 30. The housing 30 has a closed structure at least in a portion that may approach the cylinder block 1, but only that portion is open in order to form an irradiation port 30a through which the branched laser beam group passes. .. The size of the irradiation port 30a is substantially the same as the cross section of the branched laser beam group so that gas, processing debris, and foreign matter do not enter the inside of the housing 30 as much as possible. Further, although not shown, a suction unit for sucking the air around the irradiation port 30a is provided to suck and remove the foreign matter that has entered the irradiation port 30a or the foreign matter that has entered. At that time, if at least a cover covering the cylinder block 1 and the irradiation probe 3 is provided and the air in the cover is sucked, the suction efficiency is improved. Further, instead of the suction unit, a shutoff unit such as an air curtain may be provided.

The processing table 4 has a structure for attaching and fixing the work piece, and a different structure is adopted depending on the work piece. In this embodiment, the cylinder block 1 is attached to the processing table 4, but since the structure thereof is well known, it is shown only schematically here.

The cylinder block 1 attached to the processing table 4 changes its relative position with the irradiation probe 3, that is, the branched laser beam group, so that the irradiation point of the branched laser beam is set on the cylindrical inner wall surface 1a which is the irradiation surface. Can be scanned. Such a relative position change is the movement of the processing table 4 and / or the irradiation probe 3 along the X-axis, the Y-axis, the Z-axis, or two of them, and the rotation around the axis. Realized by exercise. In this embodiment, the scanning mechanism 5 is assembled or incorporated in the processing table 4 and the irradiation probe 3 in order to change the relative position. Specifically, the irradiation probe 3 is assembled with a rotation drive mechanism around the Y axis as the first scanning mechanism 51. Further, the processing table 4 incorporates a moving drive mechanism in the X-axis, Y-axis, and Z-axis directions as the second scanning mechanism 52. Here, the Y-axis direction is the axial direction of the cylinder block 1, and the X-axis direction and the Z-axis direction are the axial directions of the cylinder block 1.

The control controller 6 includes a machining control unit 60, a laser control unit 61, and a scanning control unit 62. The laser control unit 61 controls the drive of the laser light source 20 and excites an appropriate laser beam at a predetermined period in order to form a groove required for the cylinder block 1 which is a workpiece. The scanning control unit 62 includes a first scanning control unit 621 that controls the operation of the first scanning mechanism 51, and a second scanning control unit 622 that controls the operation of the second scanning mechanism 52. The scanning control unit 62 provides a program for forming various patterns of grooves on the inner wall surface 1a of the cylinder in the cylinder block 1 which is a workpiece by controlling the combination of the first scanning control unit 621 and the second scanning control unit 622. Can be stored. The machining control unit 60 determines the control parameters given to the laser control unit 61 and the scanning control unit 62 according to the groove pattern to be formed on the inner wall surface 1a of the cylinder of the cylinder block 1. Such control parameters can be directly input by the user and can be arbitrarily selected from a preset parameter table.

The basic principle of forming a plurality of grooves simultaneously on the inner wall surface 1a of the cylinder of the cylinder block 1 with a desired groove pattern will be described with reference to FIGS. 2 and 3. FIG. 2 shows a state at the start of machining, and FIG. 3 shows a state during subsequent machining. When the irradiation probe 3 and the cylinder block 1 are set at predetermined start positions, the laser light source 20 is driven. When the laser light emitted from the laser light source 20 enters the diffractive optical element 32, it branches into a plurality of branched laser lights. In the examples of FIGS. 2 and 3, nine branched laser beams are generated in a 3 × 3 square grid-like distribution. The branched laser beams are independently directed in the same direction, and irradiate the inner wall surface 1a of the cylinder of the cylinder block 1 substantially vertically. Since the branched laser beam has the energy intensity to form a depression on the inner wall surface 1a of the cylinder, a depression (indicated by P11 ... P33 in FIG. 2) is formed at the irradiation point on the inner wall surface 1a of the cylinder. .. At the same time, the first scanning mechanism 51 operates based on the scanning control signal from the scanning control unit 62, and the irradiation probe 3 rotates around the axis of the cylinder block 1. As a result, the irradiation point of the branched laser beam moves along the circumferential direction of the inner wall surface 1a of the cylinder, and the recess formed at the irradiation point extends on the line to form a linear groove (L11 ... L33 in FIG. 3). (Shown) to form. In FIG. 3, the distribution of irradiation points is in the form of a 3 × 3 square grid, and the scanning direction is along the lateral direction of the square grid. Therefore, if the lateral scanning is continued as it is, the grooves of L11, L12 and L13, the grooves of L21, L22 and L23, and the grooves of L31, L32 and L33 become one groove, and a total of three grooves are formed. To. Each of these grooves is formed by three branched laser beams. This is a special case, in which the scanning direction is tilted so that one or more branched laser beams form one groove and the other branched laser beam forms another groove. By appropriately selecting the scanning direction, it is also possible for each branched laser beam to form grooves that are independent of each other, in which case, in this example, nine grooves are formed at the same time.

In order to improve the sliding characteristics by grooving the inner wall surface 1a of the cylinder of the cylinder block 1 and further to improve the performance of the engine itself, a large number of precise grooving is required. 4 and 5 schematically show a part of the inner wall surface 1a of the cylinder in which such a large number of grooves are formed. The cylinder block is made of gray cast iron, the width of the groove is several hundredths of a millimeter, the depth of the groove is several thousandths of a millimeter, and the groove pitch is several times the width of the groove. The inclination of the groove with respect to the axial direction of the cylinder block 1 is about 45 ° to 75 °. In a laser processing apparatus that simultaneously forms a large number of grooves, a large number of branched laser beams, for example, a branched laser beam group consisting of 49 branched laser beams having a 7 × 7 lattice distribution is used. Since the laser beam is branched into 49 branched laser beams by the diffractive optical element 32, the laser light source 20 needs to excite the high-energy laser beam. On the contrary, if the intensity of the laser beam or the branched laser beam is too strong, burrs are generated on the grooved surface and the burden on the laser optical system is increased. Therefore, the laser light source 20 is configured as a device for exciting an ultrashort pulse laser.

6 and 7 show the results of an experiment on groove formation performed on the inner wall surface 1a of the cylinder of the actual cylinder block 1. In this experiment, an ultrashort pulse laser beam and a diffractive optical element 32 that produces 49 branched laser beams having a 7 × 7 grid pattern are used. FIG. 6 is an enlarged view of the inner wall surface 1a of the cylinder, and as is clear from this figure, in order to create a diamond-shaped lattice, a groove group having a groove inclination of about 60 ° with respect to the axial direction of the cylinder block 1 and a groove group of about 60 ° It is formed so as to intersect with a group of -60 ° grooves. FIG. 7 is a graph showing the cross-sectional state of the formed groove group. From this figure, each groove has a uniform depth and cross-sectional shape, and the swelling (burr) of the groove end portion during processing is also constant. It can be read that it is suppressed.

[Another Embodiment] (1) In the present invention, the diffractive optical element 32 is used as an optical element that branches from one laser beam to a plurality of branched laser beams, and the diffractive optical element 32 uses the laser beam. It is used as a phrase having a broad concept of a branched optical element, and includes, for example, a hologram lens.
(2) In the above-described embodiment, the first scanning mechanism 51 assembled on the irradiation probe 3 and the second scanning mechanism 52 incorporated in the processing table 4 are used as the scanning mechanism 5, but either one may be used. .. For example, the irradiation probe 3 may be attached to a robot manipulator or the like, and the processing table 4 may have a function of fixing the workpiece.
(3) In the above-described embodiment, the laser optical system is composed of two components, the laser device main body 2 and the irradiation probe 3, but the laser device main body 2 and the irradiation probe 3 are further composed of various components. It may be divided. Further, the geometrical arrangement of the laser optical system, that is, the propagation path of the laser beam or the branched laser beam can be modified in various ways.

The radar processing apparatus according to the present invention can be applied to processing for simultaneously forming a plurality of grooves on the surface of a work piece.

1: Cylinder block (non-processed product)
1a: Cylindrical inner wall surface 2: Laser device body 20: Laser light source 21: Mirror 3: Irradiation probe 30: Housing 30a: Irradiation port 31: Objective lens unit 32: Diffractive optical element 33: Mirror 4: Processing table 5: Scanning mechanism 51 : 1st scanning mechanism 52: 2nd scanning mechanism 6: Control controller 60: Machining control unit 61: Laser control unit 62: Scan control unit 621: 1st scanning control unit 622: 2nd scanning control unit

Claims (7)

A laser machining device that forms a plurality of linear adjacent grooves on the inner wall surface of a cylinder of an engine cylinder block.
An irradiation probe having an irradiation port for irradiating a plurality of branched laser beams branched from one laser beam onto the same inner wall surface of the cylinder as a group of branched laser beams heading in the same direction independently.
A processing table for mounting the cylinder block is provided so that the inner wall surface of the cylinder is scanned by the irradiation point of the branched laser beam.
A laser processing apparatus in which one or more of the branched laser beams form one of the plurality of grooves, and at the same time, the other branched laser beams form another one of the plurality of grooves. The laser processing apparatus according to claim 1, wherein the locus of the irradiation point of the branched laser beam in the branched laser beam group is located on a plurality of straight lines parallel to each other on a virtual plane corresponding to the inner wall surface of the cylinder. The laser processing apparatus according to claim 1 or 2, wherein the locus of the irradiation point of the branched laser beam in the branched laser beam group is located on a plurality of straight lines intersecting each other on a virtual plane corresponding to the inner wall surface of the cylinder. .. The laser processing apparatus according to any one of claims 1 to 3, wherein the intervals between the irradiation points of the branched laser beams in the branched laser beam group are the same. The laser processing apparatus according to any one of claims 1 to 4, wherein at least two or more of the branched laser beams in the branched laser beam group form the same groove. The laser processing apparatus according to any one of claims 1 to 4, wherein each of the branched laser beams in the branched laser beam group forms a different groove. A method for manufacturing a cylinder block in which a plurality of linear adjacent grooves are formed on the inner wall surface of a cylinder of an engine cylinder block.
A step of irradiating the same inner wall surface of the cylinder as a group of branched laser beams heading in the same direction independently of a plurality of branched laser beams branched from one laser beam.
The irradiation point of the branched laser beam so that one or more of the branched laser beams form one of the plurality of grooves and at the same time the other branched laser beam forms another one of the plurality of grooves. And the process of scanning the inner wall surface of the cylinder
A method for manufacturing a cylinder block.

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