JP2005305480A - Method and apparatus for repair-processing casting defect in aluminum alloy casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repair-processing technique for casting defect in an aluminum alloy casting with which the processing time is shortened and this productivity is remarkably improved. <P>SOLUTION: A robot hand provided with a bar-like tool 9 and a CCD camera rotation-driven around the axis, is inserted into the inner part of a cylinder bore 2 and the inner peripheral surface 20 of the bore is picked up while shifting downward and whether the casting defect 3, such as blow hole, exists or not, and this position, is specified. To the casting defect 3, specified at this position, the rotated bar-like tool 9 is pushed to this position at this time, to plastically fluid this defect while semi-melting with the friction heat. Thus, this casting defect 3 is eliminated by burying the plastically fluidized material M into the casting defect 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting defect repair processing method and repair processing apparatus in an aluminum alloy casting, and in particular, after performing roughing on the bore inner peripheral surface of a cylinder block that is an aluminum alloy casting, a casting hole (hole), a pinhole, etc. The present invention relates to a method and apparatus for repairing a foundry casting defect when it is found.

  The so-called linerless type that does not use a cylinder liner for the cylinder bore of the cylinder block made of aluminum alloy, or the type that coats the surface of the inner peripheral surface of the bore with a thermal spray coating, the inner peripheral surface of the bore or the thermal spray base Cast defects such as cast holes and pinholes generated on the surface cause an increase in engine oil consumption and an increase in blow-by gas. Therefore, removal or reduction of these is important for quality improvement.

  As countermeasures, for example, those described in Patent Documents 1 and 2 have been proposed in order to eliminate a cast hole on the inner peripheral surface of the bore.

  In the technique described in Patent Document 1, a vacuum arc is discharged toward the bore inner peripheral surface of an aluminum alloy cylinder block to melt its surface layer portion, and the molten metal is poured into the casting cavity to form the casting cavity. In addition to sealing, a hardened layer containing silicon as a main component is formed on the surface layer portion of the inner peripheral surface of the bore, and a sprayed layer is formed thereon by thermal spraying.

Further, in the technique described in Patent Document 2, a special tool is attached to a rotary shaft having a size that can enter the inside of the cylinder bore, and a feed in the axial direction is given while rotating the rotary shaft around its axis. The material around the casting hole is plastically deformed at the rake face and the front cut surface to repair the casting hole.
JP 2000-328222 A (FIG. 1) Japanese Patent Laying-Open No. 2003-205357 (FIG. 1)

  In the technique described in Patent Document 1, since the entire area of the inner peripheral surface of the bore is heated and melted, the processing range is wide and the processing takes a long time, and the strength is reduced due to a change in structure accompanying heating. Therefore, it is necessary to perform the work carefully, which is not preferable because the productivity is extremely lowered.

  Further, in the technique described in Patent Document 2, since the entire area of the bore inner peripheral surface is processed, the processing range is as large as that described in Patent Document 1, and the processing takes a long time, A decline in productivity is a concern.

  The present invention has been made paying attention to such problems, and in particular, provides a repairing technique for a casting defect in an aluminum alloy casting in which the processing time is shortened and the productivity is greatly improved.

  According to the first aspect of the present invention, the presence or absence of a casting defect such as a casting hole on the surface of the aluminum alloy casting and the position thereof after the roughing is performed on the surface of the aluminum alloy casting and before the finishing is performed. Is detected, and plastic processing is selectively performed only on the portion where the casting defect exists, thereby removing the casting defect.

  As the plastic working, for example, as described in claim 2, the casting defect is erased by plastically flowing a portion where the casting defect exists in a semi-molten state, and more specifically, claim 3. As described in the above, it is assumed that the portion where the casting defect exists is made to plastically flow while being in a semi-molten state by frictional heat generated by a rotary tool.

  In addition, the presence or absence of the casting defect and the detection of the position thereof are performed by image processing using, for example, an image sensor such as a CCD camera, that is, a two-dimensional image sensor, as described in claim 4. Or it shall be performed by the eddy current flaw detection method or the ultrasonic flaw detection method.

  Further, the invention described in claim 6 is an apparatus used for repairing a casting defect according to claim 3, in which a casting on the surface of an aluminum alloy casting is provided at the tip of a multi-degree-of-freedom base machine such as an industrial robot. The present invention is characterized in that detection means for detecting the presence or absence of a defect and its position, and a rotary tool that is driven to rotate are provided.

  Therefore, in the first aspect of the invention, the casting defect is blocked or eliminated by performing plastic working only on the corresponding part each time while detecting the casting defect such as a cast hole. Therefore, it is not necessary to treat the entire surface of the aluminum alloy casting.

  In the invention described in claim 6, the rotary tool is moved to a position where a casting defect such as a casting hole detected by the detecting means is detected, and is plastically flowed in a semi-molten state by frictional heat generated by the rotary tool. As a result, casting defects are blocked or eliminated.

  According to the first aspect of the present invention, by selectively performing plastic working only on a portion where a casting defect is detected, the processing range can be reduced and the processing time can be greatly shortened. Improve dramatically. Further, unlike the case where the entire surface of the aluminum alloy casting is heat-treated, there is no risk of structural change.

  According to the sixth aspect of the present invention, since the rotary tool is moved to the position of the casting defect detected by the detecting means and the processing is performed, the processing can be performed efficiently in a short time.

  FIGS. 1 to 4 are diagrams showing a more specific embodiment of the present invention, in which the inner peripheral surface of a cylinder block made of an aluminum alloy casting is cast after roughing the bore and before finishing. The example at the time of applying to a nest removal process is shown. Needless to say, the bore roughing and finishing are both machining processes such as boring.

  FIG. 1 is a diagram showing a schematic configuration of the entire system, where 1 is a cylinder block made of cast aluminum alloy, 4 is an articulated industrial robot that functions as a base machine (base machine) and a multi-degree-of-freedom type. (Hereinafter simply referred to as a robot).

  The robot 4 is controlled by the robot controller 5 by, for example, a teaching-playback system, while a hand 7 having a degree of freedom of swinging in the θ direction is attached to the tip of the arm 6. As shown in FIGS. 2 and 4, the hand 7 is configured with a substantially square tube-shaped hand frame 8 having a size capable of entering the bore inner peripheral surface 2 a of the cylinder bore 2 as a main element.

  As shown in FIGS. 2 and 3 in addition to FIG. 1, a rod-shaped tool 9 made of a steel rod can be rotated to a bearing box 12 via a thrust bearing 10 and a radial bearing 11 at the lower end of the hand frame 8. It is supported by. The rod-shaped tool 9 is equipped with a driven bevel gear 13, while a motor box 14 at the upper end of the hand frame 8 has a built-in drive motor 16 controlled by a motor control device 15. A drive-side bevel gear 18 that meshes with the bevel gear 13 is attached to the lower end of the drive shaft 17 in a vertical posture driven by 16. As a result, the rod-shaped tool 9 is driven to rotate via the drive shaft 17 and both bevel gears 18 and 13 by the activation of the drive motor 16, and the rod-shaped tool 9 remains in its rotated state as will be described later. It will be pressed against the bore inner peripheral surface 2a.

  The bearing box 12 supporting the rod-shaped tool 9 has a built-in pressure sensor 19, and the pressure sensor 19 detects the reaction force of the pressing force of the rod-shaped tool 9 against the bore inner peripheral surface 2a as described above. This detection output is captured by the robot controller 5.

  As shown in FIG. 4, a CCD camera 21 having a two-dimensional image sensor as a sensor or an image sensor as a main element is disposed at the lower end of the hand frame 8 as well as a pair of left and right illumination light sources 20. The bore inner peripheral surface 2 a can be picked up by the CCD camera 21, and the picked-up image is taken into the image processing device 22.

  Here, since the rod-shaped tool 9 performs plastic working on the bore inner peripheral surface 2a, the tip surface of the rod-shaped tool 9 is formed in a spherical shape corresponding to the curvature of the bore inner peripheral surface 2a. For example, when the diameter of the bore inner peripheral surface after rough boring, which is rough machining (rough machining), is φ90 mm, the tip surface of the rod-shaped tool 9 is formed with a spherical surface having a radius of 45 mm.

  According to the system configured as described above, as shown in FIG. 5, after the rough machining of each cylinder bore 2 in the cylinder block 1 and before the finish machining, the detection of the casting defect such as the cast hole and the removal or elimination thereof. A predetermined operation is executed for the purpose.

For example, as shown in FIG. 4, the bore inner circumferential surface 2a is divided into n equal parts in the circumferential direction and divided into a plurality of regions N ₁ , N ₂ . Using each region N ₁ , N ₂ ... Nn, the hand 7 is moved sequentially from the upper side to the lower side of the bore inner peripheral surface 2a or from the lower side to the upper side, and the presence / absence and position of the casting defect 3 such as a cast hole While the above is specified, the cast hole is erased by plastic working.

  More specifically, as shown in FIG. 4, the hand 7 is put into the cylinder bore 2 to be processed while the rod-shaped tool 9 is rotated, and the CCD inner surface 2 a is imaged by the CCD camera 21. The hand 7 is continuously moved from above to below at a predetermined speed. Then, the image captured by the CCD camera 21 is captured in real time by the image processing device 22, and the presence and position of a casting defect 3 such as a cast hole included in the image is specified by a method such as pattern matching.

  When the presence of the casting defect 3 and its position are specified, the robot 4 moves the hand 7 and presses the bar-shaped tool 9 to the position of the casting defect 3 to erase or remove the casting defect 3.

  FIG. 6 shows details when erasing or removing a casting defect 3 such as a cast hole whose position is specified, and a rotating bar-shaped tool 9 is pressed against the casting defect 3 on the bore inner peripheral surface 2a. At the same time, the bar-shaped tool 9 is reciprocated up and down by a minute amount by using the degree of freedom of the robot 4 itself (see FIGS. 1A and 1B). 3 is attached to 9 and is controlled so that the pressing force of the bar-shaped tool 9 against the bore inner peripheral surface 2a is always constant by so-called force feedback control. The rotational speed of the bar-shaped tool 9 is 500 to 2000 rpm, and the moving speed of the bar-shaped tool 9 by the robot 4 is about 60 to 300 mm / min.

  As described above, when the rotary tool 9 is pressed against the bore inner peripheral surface 2a, the material near the casting defect 3 becomes a semi-molten state due to frictional heat with the stick tool 9, and plastic flow occurs. As shown in FIG. 3C, the casting defect 3 is eliminated or eliminated by filling the casting defect 3 with the plastically flowed material M.

  Then, if the rod-shaped tool 9 is pressed against the bore inner peripheral surface 2a for a predetermined time, the rod-shaped tool 9 is immediately and rapidly separated from the bore inner peripheral surface 2a as shown in FIG. Then, the hand 7 is again moved downward at a predetermined speed, and thereafter, the above-described operation is repeated each time the casting defect 3 is detected. In addition, when the rod-shaped tool 9 is moved away from the bore inner peripheral surface 2a, the speed of the operation can be increased, so that the occurrence of unevenness on the surface to be processed can be suppressed. It is possible to reduce the machining allowance.

  Here, as shown in FIG. 7, for example, the machining allowance Q of the bore roughing (cutting allowance) prior to erasing the casting defect 3 as described above is 2 to 5 mm, and the bore finishing machining after erasing the casting defect 3 is removed. If the allowance R is about 0.3 to 0.5 mm, if the pushing amount S of the rod-shaped tool 9 against the bore inner peripheral surface 2a is set to about 0.2 to 0.3 mm, both the diameter and the depth are about 0.3 mm. The casting defect 3 of the size up to is reliably erased. In addition, after the finishing process, the thermal spray coating 23 is formed in a subsequent process with a film thickness comparable to the machining allowance R during the finishing process. The reason that the machining allowance (cutting allowance) Q of the bore rough machining gradually increases downward is because it has a draft angle during casting.

Thereafter, as shown in FIG. 4, when the hand 7 has been moved to the lower end of any one of the areas N ₁ , N ₂ ... Nn of the specific cylinder bore 2, the hand 7 is once pulled up, Thereafter, the same operation is repeated for the next adjacent region.

  As described above, according to the present embodiment, the presence / absence and position of the casting defect 3 such as a cast hole is specified while imaging the bore inner peripheral surface 2a with the CCD camera 21, and only the portion where the casting defect 3 exists is identified. Since the casting defect 3 is erased by plastic processing, the processing time can be greatly shortened compared to the case where the entire inner peripheral surface 2a of the bore is processed, thereby contributing to the improvement of productivity. .

  In the present embodiment, the processing on the bore inner peripheral surface 2a of the cylinder block 1 has been described as an example, but it goes without saying that it can be similarly applied to a machined surface of an aluminum alloy cast product other than the cylinder block 1. Further, as a method for specifying the presence or absence of the casting defect 3 and its position, it is of course possible to use an ultrasonic flaw detection method or an eddy current flaw detection method instead of the imaging method using the CCD camera.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows schematic structure of the whole system as more concrete embodiment of this invention. Explanatory drawing of the hand in FIG. FIG. 3 is an enlarged explanatory view of a main part in FIG. 2. The enlarged plan view of the principal part in FIG. Explanatory drawing which shows the process sequence of the bore | bore internal peripheral surface of a cylinder block. Process explanatory drawing which shows the detail of the deletion method of the casting defect in the system shown in FIG. The principal part expanded sectional explanatory drawing of a cylinder bore.

Explanation of symbols

1 ... Cylinder block (aluminum alloy casting)
2 ... Cylinder bore 2a ... Bore inner surface 3 ... Casting defect 4 ... Industrial robot (base machine)
5 ... Robot controller 7 ... Hand 8 ... Hand frame 9 ... Bar tool (rotary tool)
19 ... Pressure sensor (pressure detection means)
21 ... CCD camera (imaging device as detection means or sensor)
22 ... Image processing device M ... Plastic flow material

Claims (9)

After the roughing of the surface of the aluminum alloy casting and before the finishing, the presence or absence and the position of casting defects on the surface of the aluminum alloy casting are detected,
A method for repairing a casting defect in an aluminum alloy casting, wherein the casting defect is removed by selectively subjecting only a portion where the casting defect is present.   2. The casting defect in the aluminum alloy casting according to claim 1, wherein the plastic working is to erase the casting defect by plastically flowing a portion where the casting defect exists in a semi-molten state. 3. Repair processing method.   3. The repair process for a casting defect in an aluminum alloy casting according to claim 2, wherein the plastic working is to plastically flow a portion where the casting defect exists in a semi-molten state by frictional heat generated by a rotary tool. Method.   The method for repairing a casting defect in an aluminum alloy casting according to any one of claims 1 to 3, wherein the presence or absence of the casting defect and its position are detected by image processing using an image sensor as a sensor.   6. The method for repairing a casting defect in an aluminum alloy casting according to claim 1, wherein the surface of the aluminum alloy casting is a bore inner peripheral surface of the cylinder block. An apparatus used for repairing a casting defect according to claim 3,
An aluminum alloy casting characterized in that a detecting means for detecting the presence and position of a casting defect on the surface of the aluminum alloy casting and a rotary tool driven to rotate are provided at the tip of the multi-degree-of-freedom base machine. Repair equipment for casting defects in Japan.   The apparatus for repairing a casting defect in an aluminum alloy casting according to claim 6, wherein the detecting means is an image sensor. Pressure detecting means for detecting the contact pressure of the rotary tool against the surface of the aluminum alloy casting,
8. The casting in an aluminum alloy casting according to claim 7, wherein the contact pressure is feedback-controlled based on the detection output of the pressure detection means so that the contact pressure of the rotary tool is always uniform. Defect repair processing equipment.   The apparatus for repairing a casting defect in an aluminum alloy casting according to any one of claims 6 to 8, wherein the surface of the aluminum alloy casting is a bore inner peripheral surface of the cylinder block.

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