JP5357891B2 - Bonding quality control method - Google Patents

Description

The present invention relates to a joint quality management how suitable for quality assurance friction welding parts.

  Steel materials have been used for rod-like parts (hereinafter referred to as “suspension parts”) such as upper links, lower links, and radius rods. However, in recent years, aluminum alloy materials have been used from the viewpoint of weight reduction of vehicles. Is often used. For example, Patent Document 1 and Patent Document 2 disclose suspension parts in which an aluminum alloy end member is friction-welded to both ends of an aluminum alloy pipe-shaped member.

  In order to confirm the soundness and bonding strength of the friction welded portion, it is necessary to perform a tensile test or the like to confirm the breaking strength, but this method is only a sample check. In addition, due to the nature of friction welding, oxides and the like on the joint surface are discharged as burrs, but since these burrs are also generated on the inner diameter side, inspection by ultrasonic waves and X-rays is not easy.

Japanese Patent Laid-Open No. 11-156562 International Publication No. 2008/010265 Pamphlet

  The friction welding conditions and cutting conditions are appropriately and strictly controlled, so the quality of the friction welding parts that are shipped will always satisfy the design conditions, but in order to further enhance the customer's sense of security. Therefore, it is desirable to diversify quality assurance methods.

From this point of view, the present invention aims to provide a bonding quality control how suitable for quality assurance friction welding parts.

  The inventor of the present application determines the quality of the friction welded part (for example, the friction welded part of the friction welded part). It has been found that there is a correlation with the fracture mode and the fracture strength at the joint interface, etc., leading to the creation of the present invention.

That is, the joining quality control method according to the present invention is a joining quality control method performed on a friction welded part obtained by cutting out burrs generated on the outer peripheral side of the joint portion, and the joining after cutting out the burrs. Including an area counting process for counting the opening areas of the recesses appearing on the outer peripheral surface of the part, and a determination process for determining whether or not the joining quality satisfies a management standard. In the determination process, the opening area is counted It is determined that the management standard is satisfied when the value is equal to or less than a reference area, and the management standard is determined not to be satisfied when the aggregate value of the opening area is larger than the reference area. To do.

  According to the present invention, it is possible to determine whether or not the quality of the friction welded parts satisfies the management standard without performing a tensile test or the like that applies a load to the final product. It is possible to guarantee the quality of all the numbers. In addition, according to the present invention, since the size of the opening area of the recess appearing on the outer peripheral surface of the joint is used as a reference, it can be objectively and quantitatively determined whether the management standard is satisfied. Therefore, the determination result is not influenced by the experience of the determiner. In addition, poor welding of friction welding occurs when oxide or the like generated on the bonding surface before friction welding is not sufficiently discharged from the bonding portion as burrs. In this case, the opening area of the recess is large. It is assumed that

The opening area of the concave portion that appears on the outer peripheral surface of the joint portion may be directly measured, or may be measured using an image obtained by imaging the outer peripheral surface of the joint portion.
That is, other joining quality control method according to the present invention is a joint quality management method performed on friction-welded parts obtained by cutting the burr generated in the joint outer peripheral side, after resection of the burr An imaging process for imaging the outer peripheral surface of the joint portion, an image processing process for specifying a recess appearing on the outer peripheral surface on the image obtained in the imaging process, and an area of the portion specified as the recess An area counting process, and a determination process for determining whether or not the joining quality satisfies a management standard. In the determination process, when the total value of the area is equal to or less than a reference area, the management standard is satisfied. It is determined that the management standard is not satisfied when the total value of the areas is larger than the reference area.

  If image processing is used, it becomes possible to easily specify the concave portion that appears on the outer peripheral surface of the joint.

Further, another bonding quality control method according to the present invention is a bonding quality control method performed on a friction welded part obtained by cutting a burr generated on the outer peripheral side of the bonded portion, and cutting the burr. An imaging process for imaging the outer peripheral surface of the subsequent joint, and a value smaller than the luminance value of the pixel that draws the smooth surface of the joint as a reference luminance value , from among the image data obtained in the imaging process, a dark pixel extraction step of extracting a pixel luminance value is equal to or less than the reference brightness value, and the dark pixel extraction process pixel tally process of aggregating the number of pixels extracted with, or bond quality meets the control standards A determination process for determining whether or not, in the determination process, when the number is equal to or less than a reference pixel number, it is determined that the management criterion is satisfied, and the number is greater than the reference pixel number Meet the above management criteria It determines that were not, characterized in that.

The joint quality management method, "luminance value of the pixel demarcating drawing a recess (density value) of the luminance values of the pixels demarcating drawing a smooth surface around the recess becomes smaller than the (density value)" the property of use It is a thing. According to this bonding quality control method, it becomes possible to determine more objectively and quantitatively whether or not the management standard is satisfied. Note that the “brightness value” in the case where the shade of a pixel is expressed by a gradation is a gradation value.

  When the base material of the friction welded part is a heat-treatable aluminum alloy, the stress generated in the cross section other than the bonded interface before the stress generated at the bonded interface reaches the fracture stress at the bonded interface. It is desirable to set the finished outer diameter of the joint (the outer diameter of the joint after removing the burr on the outer periphery of the joint) so that the fracture stress in the cross section is reached. In this case, the imaging process may be performed after the burrs are removed so as to have the finished dimensions. In this way, it is possible to ensure that the bonding interface does not become the weakest part.

  In the present invention, the total of the opening area of the recess or the total of the number of pixels is preferably measured over the entire circumference of the joint, but can also be determined by measuring partially.

  According to the present invention, it is possible to guarantee the quality of the friction welded part by an objective determination criterion.

(A) is sectional drawing for demonstrating the structure of the friction welding part which is a test object, (b) is an enlarged view of the X section of (a). It is a schematic diagram for demonstrating the structure of the joining quality control apparatus which concerns on embodiment of this invention. It is a flowchart for demonstrating the procedure of the joining quality control method which concerns on embodiment of this invention. (A) is a schematic diagram of the image imaged with the imaging means, (b) is a schematic diagram which shows the binary image obtained by performing the binarization process with respect to the image of (a). It is a graph which shows the relationship between the opening area of a recessed part, and a breaking load.

A Friction welding part a Joining part b Burr c Concave part 3 Imaging means 4 Extraction means 5 Pixel count totaling means 6 Determination means

  The joining quality control method according to the present embodiment is a joining quality control method performed on a friction welded part obtained by cutting off burrs generated on the outer peripheral side of the joint.

  In the following embodiments, a case where the friction welding component is a suspension rod which is a kind of suspension component is illustrated, but the purpose of the friction welding component is not limited.

First, the configuration of the friction welding component will be briefly described.
As shown in FIG. 1A, the friction welding component A to be inspected is formed by friction welding the end members A2 and A2 to both ends of a pipe-like member A1. The pipe-shaped member A1 and the end member A2 are both obtained by processing an extruded shape made of an aluminum alloy. There are no particular restrictions on the type of aluminum alloy, but when the friction welded part A is used as a suspension part, it is an Al—Mg—Si based alloy that has been subjected to T6 treatment (a 6000 standard aluminum alloy in accordance with JIS standard and after solution treatment). It is desirable to have a quenching treatment followed by an artificial aging treatment). In particular, an Al—Mg—Si based alloy (JIS standard aluminum alloy 6061-T6) treated with T6 has high strength (0.2% proof stress of 245 MPa or more) and durability (stress corrosion cracking resistance and weather resistance). It is even more desirable.

  When the pipe-shaped member A1 and the end members A2 and A2 are abutted while being relatively rotated, the base material around the abutting surface is plastically fluidized by frictional heat, and both are frictionally joined. As shown in FIG. 1B, a part of the plastic fluidized base material is pushed out into and out of the joint a to become a burr b. Since the oxide film and deposits, etc. present on the end face of the pipe-like member A1 and the end face of the end member A2 are discharged together with the burr b, if friction welding is performed under appropriate conditions, the oxide film or the like A non-existent bonding interface J is formed.

  Then, the burr | flash b generate | occur | produced on the outer peripheral side of the junction part a is excised, and if the outer peripheral surface of the junction part a is shape | molded smoothly, the friction welding part A will be obtained. The finished outer diameter dimension of the joint part a (the outer diameter dimension of the joint part a after the burr b on the outer peripheral side is cut) can be set to an appropriate size, but the joint interface J does not become the weakest part. In order to guarantee that, the stress generated at the cross section other than the joint interface J reaches the fracture stress at the cross section before the stress generated at the joint interface J reaches the fracture stress at the joint interface J. It is desirable to set this.

  By the way, the shape of the burr b changes depending on the manufacturing error of the pipe-shaped member A1 and the end member A2, the installation error on the friction welding machine, the operation error of the friction welding machine, the temperature, and the like, so that it has a predetermined finished outer diameter. When the burr b on the outer side of the joint portion is cut out as described above, a concave portion (including a groove-shaped one) c may appear on the outer peripheral surface of the joint portion a after the burr b is cut off. Note that the bonding quality control method according to the present embodiment determines whether or not the bonding quality satisfies the management standard by using the size of the opening area of the recess c or various quantities correlated with the size of the opening area. To do.

  With reference to FIG. 2, the structure of the joining quality control apparatus based on this embodiment used suitably for the said joining quality control method is demonstrated in detail.

  The bonding quality control apparatus includes a component holding unit 1, a light source 2, an image pickup unit 3, an extraction unit 4, a pixel count counting unit 5, a determination unit 6, a storage unit 7, a display unit 8, a speaker 9, and the like.

  Of the joint quality control apparatus, the extraction means 4, the pixel number counting means 5, the determination means 6, the storage means 7, and the display means 8 are realized by a general-purpose computer. This general-purpose computer exchanges data with a CPU (Central Processing Unit), a storage device such as RAM, ROM, and hard disk (storage unit 7), a display device such as a display (display unit 8), and an imaging unit 3. It is configured to include an interface for performing functions, and functions as the extraction unit 4, the pixel number counting unit 5, and the determination unit 6 by executing various programs stored in the storage unit 7 by the CPU.

  The component holding means 1 is a device that rotates the friction welding component A around the central axis, and supports the chuck 11 that holds one end of the friction welding component A and the other end of the friction welding component A so as to be slidably rotatable. A pedestal 12, a power source 13 that applies a rotational force to the chuck 11, and a control unit 14 that controls the power source 13. The power source 13 includes, for example, a stepping motor or a motor with a rotary encoder (servo motor). The control unit 14 acquires information (for example, an encoder signal output from a rotary encoder) regarding the rotation amount and rotation speed of the output shaft 13a of the power source 13, and outputs this to a general-purpose computer.

  The light source 2 illuminates the joint portion a of the friction welding component A, and is disposed obliquely above the joint portion a in this embodiment. Although there is no restriction | limiting in the kind of light source 2, It is desirable to use a white fluorescent lamp and white LED.

  The imaging means 3 images the outer peripheral surface of the junction part a, and is arrange | positioned above each of the right and left junction parts a and a in this embodiment. The image pickup means 3 includes an image pickup device (one-dimensional image sensor) such as a CCD linear image sensor or a CMOS linear image sensor. In this embodiment, black-and-white grayscale image data (luminance (brightness) information for each pixel) is provided. Is obtained). The acquired image data is output to a general-purpose computer and stored in the storage means 7. Note that an area image sensor may be used as the image sensor, and an image sensor capable of acquiring color grayscale image data may be used.

  The extraction unit 4 has a function of extracting pixels whose luminance value (density value) is equal to or lower than the reference luminance value from the image data acquired by the imaging unit 3. Specifically, the extracting unit 4 determines whether or not the luminance value is equal to or lower than the reference luminance value for each of a large number of pixels constituting the image data, the function of reading the image data from the storage unit 7, and A function of distinguishing a pixel determined to be equal to or less than a luminance value from other pixels, a function of writing a determination result in the storage unit 7, and the like are provided.

The internal recess c shown in FIG. 1 (b), as compared to the smooth surface around the recesses c since prone to "shadow", the pixel demarcating drawing recess c, around the recesses c smoothing It tends to be darker than the pixel demarcating drawing plane (see FIG. 4 (a)). That is, the luminance values of the pixels demarcating draw the recesses c (density value) is in the small tends than the luminance value of the pixel demarcating drawing a smooth surface around the recesses c. Therefore, in order to identify the pixel demarcating drawing recess c sets a reference luminance value a smooth surface of the joint a value smaller than the luminance value of the pixel demarcating drawing, the reference brightness value or less of the luminance value The reference luminance value is preferably set to a value that does not detect fine grooves or the like that inevitably occur in the burr cutting operation.

  Incidentally, the color of a pixel whose luminance value is equal to or lower than the reference luminance value is, for example, black that has a luminance value (density value) of zero (minimum gradation value = 0 when the gradation of the pixel is expressed by gradation). At the same time, the image data obtained by replacing the color of the pixel whose luminance value is larger than the reference luminance value with, for example, white (the maximum gradation value when the gradation of the pixel is expressed in gradation) is maximized. If it is created and displayed on the display means 8, the position of the pixel whose luminance value is equal to or lower than the reference luminance value can be confirmed on the screen (see FIG. 4B).

  The pixel number counting means 5 counts the number N of pixels (hereinafter referred to as “dark color pixels”) extracted by the extracting means 4. The counting result is stored in the storage means 7.

Determining means 6, the friction welding quality of pressure parts is intended to determine whether to satisfy the control criterion, management criterion when the number N of the dark pixels included in the image data is equal to or less than the reference pixel number N ₀ It determines that meets determines that the number N does not satisfy the management criteria is larger than the reference pixel number N _0. Since the number N of dark pixels is related to the size of the opening area of the recess c, setting the reference pixel number N ₀ sets the allowable value (reference area) of the opening area of the recess c. It is none other than. The reference pixel number N ₀ (reference area) may be appropriately set in consideration of the performance required for the friction welding component A (breaking load and aesthetics), but the number N of dark pixels (the opening area of the recess c) It is desirable to confirm the correlation between the size) and the breaking load by a tensile test or analysis.

  In addition, this inventor conducted test research about the relationship between the magnitude | size of the opening area of the recessed part c, and the quality of friction welding components, and discovered that these had a correlation (refer FIG. 5).

  FIG. 5 is a graph showing the relationship between the opening area of the recess c (the opening area obtained by measurement over the entire circumference of the joint part a) and the breaking load. This graph is obtained by actually measuring the opening area and the breaking load of the suspension rod (friction welding part). The suspension rod used in the test was obtained by friction welding the pipe-shaped member A1 and end members A2, A2 formed using an extruded profile (material: JIS standard aluminum alloy 6061 treated with T6). (See (a) of FIG. 1). Before the friction welding, the outer diameter of the pipe-shaped member A1 and the outer diameter of the cylindrical portion of the end member A2 are both 25 mm, and the thickness of the pipe-shaped member A1 and the thickness of the cylindrical portion of the end member A2 are , Both are 4.5 (mm). After the friction welding, the burr b is cut so that the finished outer diameter of the joint a (the outer diameter of the joint a after the outer burr b is cut) is 26.5 (mm), While measuring the opening area of the recessed part c which appeared on the outer peripheral surface of the junction part a over the perimeter (1 round), the fracture | rupture load was measured. In this test, image processing is performed on the image data acquired by the imaging means 3 (the pixel color whose luminance value is equal to or lower than the reference luminance value is replaced with black, and the pixel whose luminance value is larger than the reference luminance value is detected. The process of replacing the color with white) was performed, and the area of the black portion was measured to obtain the opening area of the recess c. The breaking load was obtained by performing a tensile test after friction welding. In the tensile test, the end members A2 and A2 were gripped by the chuck of the tensile tester to apply a tensile force to the suspension rod, and the load when the suspension member broke at any point was defined as a “breaking load”. In the graph of FIG. 5, the white square plot indicates that the fracture occurred at the joint interface J (friction welding surface), and the filled diamond-shaped plot indicates that the fracture occurred at other than the joint interface J. Yes. In addition, the opening area in the graph of FIG. 5 is the opening area in the joint part a on the fractured side, and data is plotted with this as the horizontal axis.

From the graph of FIG. 5, the breaking load is greatest when the opening area is 0 (zero), the breaking load gradually decreases as the opening area increases, and decreases rapidly when the opening area exceeds a certain value. I can read. Further, when the opening area exceeds a certain value (about 1.8 (mm ^{2 in} FIG. 5)), the fracture occurs at the joint interface J, and the joint failure at the joint interface J causes a decrease in the fracture load. I found out that The reference area (reference pixel number N ₀ ) may be set so that the fracture load required for the friction welded part A can be reliably obtained in consideration of the tendency shown in FIG. For example, if it is desired to guarantee 85 (kN) as the breaking load, a horizontal line passing through the scale 85 (kN) on the vertical axis (a line segment parallel to the horizontal axis) is drawn, and the horizontal line and the graph (approximate curve) A vertical line (a line segment parallel to the vertical axis) passing through the intersection is drawn, and any value below the value at the intersection of the vertical line and the horizontal axis (1.67 (mm ² ) in FIG. 5) is used as the reference area. You only have to set it.

Next, mainly with reference to FIG. 2 and FIG. 3, the joining quality control method according to the present embodiment will be described in detail.
First, the friction welding component A obtained by cutting off the burr b (see FIG. 1B) is held by the component holding means 1 in a state where the power source 13 is stopped. Further, the light source 2 is caused to emit light, and the illumination light is irradiated from the obliquely upper part of the joint part a of the friction welding component A toward the joint part a.

(Imaging process S1)
When the preliminary preparation is completed, the outer peripheral surface of the joint portion a is imaged while rotating the friction welding component A around the central axis. That is, a power source 13 is operated by operating a start switch (not shown) connected to the control unit 14, and the outer peripheral surface of the joint portion a is imaged by the imaging unit 3. The acquired image data is stored in the storage means 7. It is desirable that the timing at which imaging is started be interlocked with the movement of the power source 13 (for example, a command pulse signal for operating the stepping motor or an encoder signal output from the rotary encoder). The timing for ending the imaging may be triggered by a signal indicating that the output shaft 13a of the power source 13 has made one revolution. If the acquisition timing of the image data is synchronized with the operation of the power source 13, the amount of image data can be minimized, so that the time required for image processing can be shortened.

(Dark color pixel extraction process S2)
When the imaging process S1 is completed, pixels (dark pixels) whose luminance value is equal to or less than the reference luminance value are extracted from the image data stored in the storage unit 7. In the dark color pixel extraction step S2 of the present embodiment, the extraction unit 4 reads out the image data stored in the storage unit 7, and the luminance value is less than or equal to the reference luminance value for each of a large number of pixels constituting the image data. Whether it is a dark pixel or not, and a pixel determined to be equal to or less than the reference luminance value is extracted. It should be noted that the dark pixel extraction process may be performed on all of the acquired image data (that is, all the pixels), or a part of the image data (for example, the outer peripheral surface of the joint portion a and the joint interface J). The dark pixel extraction process may be performed on the image data corresponding to the belt-like region along the intersection line.

(Pixel count process S3)
Subsequently, the number N of dark color pixels extracted in the dark color pixel extraction step S2 is totalized. In the pixel number counting step S3 of the present embodiment, the pixel number counting unit 5 totals the number N of pixels determined to be dark pixels by the extracting unit 4, and stores the totaling result in the storage unit 7.

(Judgment process S4)
Then, it is determined that when the number N of the dark pixels obtained by the pixel number tabulation process S3 is equal to or less than the reference pixel number N ₀ meets management standards, if the number N is larger than the reference pixel number N ₀ Determines that the management criteria are not met. The decision process S4 in the present embodiment, determination unit 6 reads the number N of the dark pixel from the storage means 7, the number N is to or less than the reference pixel number N _0.

  In the determination process S4, when it is determined that “the management standard is not satisfied (failed)”, the failure is displayed on the display means 7 (see FIG. 2), or an alarm sound or the like. Is output from the speaker 9 to give a warning to the worker. Although illustration is omitted, when it is determined that “the management standard is satisfied (passed)” in the determination step S 4, the display unit 7 displays that it is passed, or outputs a chime sound or the like from the speaker 9. You can do it.

  According to the joining quality control device and the joining quality control method according to the present embodiment described above, whether or not the quality of the friction welded part A satisfies the management standard without performing a tensile test or the like that places a load on the final product. Therefore, it is possible to guarantee the quality of all the friction welded parts A produced. In addition, according to the bonding quality control method according to the present embodiment, the number N of dark pixels having a correlation with the opening area of the recess c is used as a reference, so whether or not the control standard is satisfied can be objectively and quantitatively determined. The determination result is not affected by the experience of the determiner.

  In this embodiment, the number N of dark pixels is counted to determine whether or not the management standard is satisfied. In addition, the area of the portion specified as the recess c is counted. Thus, it may be determined whether or not the management standard is satisfied.

That is, after specifying the recess c appearing on the outer peripheral surface of the joint a on the image obtained in the imaging process (image processing process), the area of the part specified as the recess a is totaled (area counting process). ), It is determined that the management standard is satisfied when the area total value M is equal to or less than the reference area M ₀ , and the management standard is not satisfied when the area total value M is larger than the reference area M _0. You may judge.

  In order to specify the concave portion c on the image, for example, binarization processing is performed on the image data acquired by the imaging unit 3 using the reference luminance value as a threshold value to generate binary image data. Good (see FIG. 4B). Further, in order to obtain the total value M of the area of the portion specified as the recess a, for example, a pixel having a luminance value of zero (or a gradation value of zero) is extracted from binary image data, The total number may be the total value M of the area.

Claims (4)

A joining quality control method performed on a friction welding part obtained by cutting off burrs generated on the outer peripheral side of the joint,
An imaging process for imaging the outer peripheral surface of the joint after excising the burr;
A pixel whose luminance value is equal to or less than the reference luminance value is extracted from the image data obtained in the imaging process using a value smaller than the luminance value of the pixel that draws the smooth surface of the joint as a reference luminance value. Dark pixel extraction process,
A pixel count counting process for counting the number of pixels extracted in the dark pixel extraction process;
A determination process for determining whether or not the joining quality satisfies the management standard,
In the determination process, it is determined that the management criterion is satisfied when the number is equal to or less than the reference pixel number, and it is determined that the management criterion is not satisfied when the number is larger than the reference pixel number. A bonding quality control method characterized by that. A joining quality control method performed on a friction welding part obtained by cutting off burrs generated on the outer peripheral side of the joint,
An imaging process for imaging the outer peripheral surface of the joint after excising the burr;
An image processing process for identifying a recess appearing on the outer peripheral surface on the image obtained in the imaging process;
An area counting process for counting the area of the portion specified as the recess,
A determination process for determining whether or not the joining quality satisfies the management standard,
In the determination process, it is determined that the management standard is satisfied when the total value of the area is equal to or less than a reference area, and the management standard is not satisfied when the total value of the area is larger than the reference area. A quality control method for joining, characterized in that A joining quality control method performed on a friction welding part obtained by cutting off burrs generated on the outer peripheral side of the joint,
An area counting process for counting the opening area of the recesses that appeared on the outer peripheral surface of the joint after excising the burr;
A determination process for determining whether or not the joining quality satisfies the management standard,
In the determination process, it is determined that the management standard is satisfied when the total value of the opening area is equal to or less than a reference area, and the management standard is satisfied when the total value of the opening area is larger than the reference area. It determines that it is not, The joining quality control method characterized by the above-mentioned. The base material of the friction welding part is a heat-treatable aluminum alloy,
Before the stress generated at the joint interface reaches the fracture stress at the joint interface, the finished outer diameter of the joint is set so that the stress generated at the cross section other than the joint interface reaches the fracture stress at the cross section. The joining quality control method according to any one of claims 1 to 3, wherein the imaging process is performed after the burr is cut so as to have the finished dimension.

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