JP2007315825A - Surface inspecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface inspecting device capable of making various sensitivity characteristics, corresponding to the kind or the like of a flaw. <P>SOLUTION: The surface inspection device 1 has a detection unit 5 for irradiating the inner peripheral surface 100a of an inspection target 100 from a laser diode 11 via a floodlight projecting fiber 13 and detecting the intensity of the reflected light of the inspection light. The detection unit includes a first light detecting fiber group 14A arranged in the vicinity of the floodlight projecting fiber 13, a second light detecting fiber group 14B arranged at the outside of the first light detecting fiber group and photodetectors 12A and 12B, respectively connected to these fiber groups. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface inspection apparatus that detects the intensity of reflected light of inspection light applied to the surface of an inspection object and inspects the surface of the inspection object based on the intensity of the detected reflected light.

  As an apparatus for inspecting the inner peripheral surface of a cylindrical inspection object, the inspection head is inserted into the inspection object by feeding it in the axial direction while rotating the axial inspection head around its axis. The inspection light is irradiated onto the inspection object from the outer periphery of the inspection object, and the inner peripheral surface of the inspection object is sequentially scanned from once to the other end in the axial direction, and the reflected light from the inspection object corresponding to the scanning is inspected by the inspection head. There is known a surface inspection apparatus that receives light via a light source and discriminates the state of an inspection object, for example, the presence or absence of a defect or the like based on the intensity of the received reflected light (see, for example, Patent Document 1).

JP-A-11-281582

  In the surface inspection apparatus of Patent Document 1, a plurality of light receiving fibers that receive reflected light are arranged adjacent to a light projecting fiber that projects inspection light, and these optical fibers are held by a fiber holding cylinder. have. Since this detection means has a fixed positional relationship such as the distance between the light projecting fiber and the light receiving fiber, the sensitivity characteristic of the detection means with respect to changes in the properties of the reflected light such as the direction and intensity of the reflected light is also fixed. Since the nature of the reflected light is characterized by the type of defects present in the inspection object, conventional surface inspection devices receive light so that the detection means has a sensitivity characteristic that can detect defects to be detected from the inspection object. The position of the fiber is set.

  As described above, in the conventional surface inspection apparatus, the sensitivity characteristic of the detection means is fixed to the sensitivity characteristic that can detect the defect to be detected. For example, when the type of the defect to be detected changes, the defect is sufficiently detected. There are problems such as being unable to detect, and when a part that should be distinguished from a defect is newly set, that part is erroneously detected as a defect.

  Accordingly, an object of the present invention is to provide a surface inspection apparatus capable of creating various sensitivity characteristics according to the type of defect.

  The surface inspection apparatus (1) of the present invention irradiates the surface (100a) of the inspection object (100) from the light source (11) via the light projecting fiber (13), and reflects the reflected light of the inspection light. In a surface inspection apparatus that has a detection means (5) for detecting intensity and inspects the surface of the object to be inspected based on a detection result of the detection means, the detection means is arranged around the light projecting fiber. A first light receiving fiber group (14A) composed of a plurality of light receiving fibers (14) capable of guiding the reflected light, and disposed outside the first light receiving fiber group as viewed from the light projecting fiber. A second light receiving fiber group (14B) composed of a plurality of light receiving fibers (14) capable of guiding the reflected light, and a signal corresponding to the intensity of the reflected light guided by the first light receiving fiber group is output. First photoelectric conversion hand And (12A), and second photoelectric conversion means for outputting a signal corresponding to the intensity of the reflected light guided by the second light receiving fiber group (12B), solving the above problems by providing a.

  According to this inspection apparatus, the second light receiving fiber group is disposed outside the first light receiving fiber group, and these fiber groups are different in positional relationship with the light projecting fiber. For this reason, one detection means has a plurality of different sensitivity characteristics. Therefore, various sensitivity characteristics can be created by selectively using the signals of the first photoelectric conversion means and the signals of the second photoelectric conversion means according to the type of defect to be detected, or by combining these signals. Is possible.

  In one aspect of the inspection apparatus of the present invention, the first signal (Ps1) output from the first photoelectric conversion means and the second signal (Ps2) output from the second photoelectric conversion means are used. Combining processing means (601) for combining based on a predetermined arithmetic rule, and arithmetic rule setting means (602) for setting the predetermined arithmetic law so that the sensitivity of the detecting means has a predetermined sensitivity characteristic. May be. There is no limitation on the calculation rule set by the calculation rule setting means. The calculation rule setting means may hold a plurality of types of calculation rules in advance and select and set an appropriate calculation rule from them. For example, when a light-receiving fiber group having a light-receiving area obtained by summing the light-receiving areas of the respective fiber groups is set by setting an arithmetic rule for simply adding the first signal and the second signal, that is, the light-receiving fiber Sensitivity characteristics that are substantially the same as when the diameter is increased can be obtained.

  By the way, when the object to be inspected is a cast product and the surface to be inspected is cut, a hollow formed on the surface of the cast product is detected as a defect, and at the same time, a slight depression formed on the surface by the cutting process is detected. It is required to distinguish from a defective casting hole. In the case where a cast hole exists on the surface, the intensity of the reflected light decreases because the cast hole is hardly reflected even when irradiated with the inspection light. On the other hand, the depression formed on the surface changes the direction of the reflected light. Therefore, if the sensitivity of the detection means with respect to the change in the angle of the reflected light is sensitive, that is, the sensitivity characteristic has a narrow allowable range with respect to the angle range of the reflected light, the detection means cannot receive the reflected light reflected by the depression on the surface. There is a case. Thereby, the intensity | strength of the reflected light which light-receives falls, and it becomes difficult to attach a cast hole and a hollow.

  Therefore, in one aspect of the inspection apparatus of the present invention, the calculation rule setting means is substantially free from an angle change in which the sensitivity of the detection means relating to an angle change of reflected light from the surface of the inspection object is within a predetermined range. The predetermined calculation rule may be set so that the sensitivity characteristic is flat. In this case, if a predetermined range is set corresponding to the angle change width of the reflected light from the depression, the sensitivity characteristic within the range is substantially flat. Therefore, the reflected light from the depression is reflected from the surface without the depression. Can receive light with the same intensity. Therefore, the distinction between the cast hole and the hollow becomes clear and the inspection accuracy is improved.

  The sensitivity characteristics regarding the angle change of the reflected light of each of the first and second light receiving fiber groups are the distance between these optical fiber groups, the distance between each fiber group and the light projecting fiber, and the light receiving fibers constituting these fiber groups. Depends on the physical configuration such as the size of the diameter. Accordingly, an arithmetic rule for obtaining such flat sensitivity characteristics is appropriately set in consideration of the sensitivity characteristics of the first light receiving fiber group and the sensitivity characteristics of the second light receiving fiber group with respect to the change in angle of the reflected light. Is done. For example, the calculation rule setting means may set a calculation rule for adding a value obtained by multiplying the second signal by a predetermined value to the first signal as the predetermined calculation rule. A substantially flat sensitivity characteristic can also be obtained by such a calculation rule.

  By the way, when the surface of the object to be inspected is machined, chips from the machining may adhere to the surface, and there is a demand to detect the presence of the chips as a defect. When the inspection light applied to the chips hardly reflects or when the direction of the reflected light deviates greatly, the intensity of the reflected light received decreases, so that the chips can be detected. However, since the chips are not in a uniform shape, the presence of the chips may be overlooked if the inspection light irradiated on the chips reflects in the same manner as a normal surface.

  Therefore, in one aspect of the inspection apparatus of the present invention, the calculation rule setting unit is configured such that the sensitivity of the detection unit relating to a change in the distance to the reflection position of the inspection object is close to the reflection position by a predetermined distance. The predetermined calculation rule may be set so that the sensitivity characteristic has a negative peak. According to this, for example, by setting the predetermined distance to the average size of the chips, the intensity of the reflected light received due to the presence of the chips becomes a negative value and the chips can be detected. The risk of overlooking the presence of chips is reduced. Since the calculation rule for obtaining such sensitivity characteristics depends on the physical configuration of the detection means as described above, the sensitivity characteristics and the first sensitivity characteristics of the first light receiving fiber group regarding the change in distance to the reflection position of the inspection object are described. It is set appropriately in consideration of the sensitivity characteristics of the two light receiving fiber groups. For example, the calculation rule setting means may set a calculation rule for subtracting the second signal from the first signal as the predetermined calculation rule. Even with such a calculation rule, a sensitivity characteristic having a negative peak can be obtained when the reflection position is close to a predetermined distance.

  The inspection apparatus of the present invention may be configured as an apparatus for inspecting a planar surface of an object to be inspected, or may be configured as an apparatus for inspecting a non-planar surface. For example, a cylindrical inner peripheral surface (100a) is provided as the surface of the object to be inspected, and the detection means is directed from the outer periphery of the inspection head (16) extending in a shaft shape toward the inner peripheral surface of the cylindrical body. The apparatus may further comprise linear drive means (30) for irradiating the inspection light and moving the inspection head in the axial direction, and rotational drive means (40) for rotating the inspection head around the axis.

  In addition, in the above description, in order to make an understanding of this invention easy, the reference sign of the accompanying drawing was attached in parenthesis, but this invention is not limited to the form of illustration by it.

  As described above, according to the present invention, the second light receiving fiber group is disposed outside the first light receiving fiber group, and these fiber groups are different from each other in the positional relationship with the light projecting fiber. Therefore, one detection means has a plurality of sensitivity characteristics different from each other. Therefore, various sensitivity characteristics can be created by selectively using the signals of the first photoelectric conversion means and the signals of the second photoelectric conversion means according to the type of defect to be detected, or by combining these signals. Is possible.

  FIG. 1 shows a schematic configuration of a surface inspection apparatus according to an embodiment of the present invention. The surface inspection apparatus 1 is an apparatus suitable for inspection of the inner peripheral surface 100a of the cylindrical body of the inspection object 100. The surface inspection apparatus 1 executes such an inspection and outputs information related to the inner peripheral surface 100a of the inspection object 100. The surface inspection apparatus 1 controls the operation of each part of the inspection mechanism 2, and the inspection mechanism 2 outputs the information. And a control unit 3 for processing the processed information. Further, the inspection mechanism 2 projects inspection light onto the inspection object 100 and receives the reflected light from the inspection object 100, and gives a predetermined operation to the detection unit 5. Drive unit 6.

  The detection unit 5 receives a laser diode (hereinafter referred to as LD) 11 as a light source of inspection light and reflected light from the inspection object 100, and the amount of the reflected light per unit time (reflected light intensity). Two photo detectors (hereinafter referred to as PDs) 12A and 12B that output electric signals having a current or voltage corresponding to the above, and a light projecting fiber 13 that guides the inspection light emitted from the LD 11 toward the inspection object 100; A first light receiving fiber group 14A for guiding reflected light from the inspection object 100 to the PD 12A, a second light receiving fiber group 14B for guiding reflected light from the inspection object 100 to the PD 12B, and their light projecting fibers 13 and the receiving fiber groups 14A and 14B are held in a bundled state, and a hollow shaft inspection head 16 is provided coaxially on the outside of the holding cylinder 15. There.

  FIG. 2 shows tip portions (right end portions in FIG. 1) of the light projecting fiber 13 and the light receiving fiber groups 14A and 14B held by the holding cylinder 15. The light projecting fiber 13 is disposed on the center line of the holding cylinder 15, and the first light receiving fiber group 14 </ b> A includes six light receiving fibers 14 disposed around the light projecting fiber 13. The second light receiving fiber group 14 </ b> B is composed of twelve light receiving fibers 14 disposed outside the first light receiving fiber group 14 </ b> A when viewed from the light projecting fiber 13. The light projecting fiber 13 and the light receiving fibers 14 constituting each of the light receiving fiber groups 14A and 14B are fixed to each other by a bonding means such as a resin-based adhesive (not shown) to prevent displacement. The number of the light receiving fibers 14 constituting each of the first light receiving fiber group 14A and the second light receiving fiber group 14B is not limited, and an appropriate number may be adopted.

  As shown in FIG. 1, at the tip of the holding cylinder 15, the inspection light guided through the light projecting fiber 13 is beam-shaped along the direction of the axis AX of the inspection head 16 (hereinafter referred to as the axial direction). And a lens 17 that collects the reflected light that travels in the direction opposite to the inspection light along the axial direction of the inspection head 16 onto the light receiving fiber 14. A mirror 18 as an optical path changing means is fixed to the tip portion (right end portion in FIG. 1) of the inspection head 16, and a light transmission window 16 a is provided on the outer periphery of the inspection head 16 so as to face the mirror 18. ing. The mirror 18 changes the optical path of the inspection light emitted from the lens 17 toward the light transmission window 16a, and travels the optical path of the reflected light incident from the light transmission window 16a into the inspection head 16 toward the lens 17. Change to

  The drive unit 6 includes a linear drive mechanism 30, a rotation drive mechanism 40, and a focus adjustment mechanism 50. The linear drive mechanism 30 is provided as a moving unit that moves the inspection head 16 in the axial direction thereof. In order to realize such a function, the linear drive mechanism 30 includes a base 31, a pair of rails 32 fixed to the base 31, and a slider 33 movable along the rail 32 in the axial direction of the inspection head 16. Further, a feed screw 34 disposed in parallel to the axis AX of the inspection head 16 and a motor 35 that rotationally drives the feed screw 34 are provided on the side of the slider 33. The slider 33 functions as a means for supporting the entire detection unit 5. That is, the LD 11 and the PDs 12 </ b> A and 12 </ b> B are fixed to the slider 33, the inspection head 16 is attached to the slider 33 via the rotation drive mechanism 40, and the holding cylinder 15 is attached to the slider 33 via the focus adjustment mechanism 50. Further, the feed screw 34 is screwed into a nut 36 fixed to the slider 33. Therefore, when the feed screw 34 is rotationally driven by the electric motor 35, the slider 33 moves along the rail 32 in the axial direction of the inspection head 16, and accordingly, the entire detection unit 5 supported by the slider 33 is moved. It moves in the axial direction of the inspection head 16. By driving the detection unit 5 using the linear drive mechanism 30, the irradiation position of the inspection light on the inner peripheral surface 100 a of the inspection object 100 can be changed with respect to the axial direction of the inspection head 16.

  The rotation drive mechanism 40 is provided as a rotation drive unit that rotates the inspection head 16 around the axis AX. In order to realize such a function, the rotation drive mechanism 40 includes a bearing (not shown) that supports the inspection head 16 so as to be rotatable around the axis AX, an electric motor 41 as a rotation drive source, and the electric motor 41. And a transmission mechanism 42 that transmits the rotation of the rotation to the inspection head 16. As the transmission mechanism 42, a known rotation transmission mechanism including a belt transmission device and a gear train may be used. By transmitting the rotation of the electric motor 41 to the inspection head 16 via the transmission mechanism 42, the inspection head 16 rotates around the axis AX with the mirror 18 fixed therein. By rotating the inspection head 16 using the rotation drive mechanism 40, the irradiation position of the inspection light on the inner peripheral surface 100a of the inspection object 100 can be changed in the circumferential direction. Then, by combining the movement of the inspection head 16 in the axial direction and the rotation around the axis AX, the inner peripheral surface 100a of the inspection object 100 can be scanned over the entire surface with the inspection light. . Note that the holding cylinder 15 does not rotate when the inspection head 16 rotates. Furthermore, the rotary drive mechanism 40 is provided with a rotary encoder 43 that outputs a pulse signal corresponding to the rotation position of the inspection head 16. The rotary encoder 43 is attached to the inspection head 16 and rotates integrally. The rotary encoder 43 is formed with a plurality of detection holes (not shown) arranged at predetermined intervals along the circumferential direction, and detection of the disk 43a. A pulse generation unit 43b that generates a pulse corresponding to the position of the hole. The pulse signal from the rotary encoder 43 is used by the control unit 3.

  The focus adjusting mechanism 50 focuses the inspection light on the inner peripheral surface 100a of the inspection object 100, and the reflected light from the inner peripheral surface 100a is either the first light receiving fiber group 14A or the second light receiving fiber group 14. On the other hand, it is provided as a focus adjusting means for driving the holding cylinder 15 in the direction of the axis AX so as to focus. In order to realize the function, the focus adjustment mechanism 50 is disposed between the support plate 51 fixed to the base end portion of the holding cylinder 50 and the slider 33 and the support plate 51 of the linear drive mechanism 30 to dispose the support plate 51. A rail 52 that guides in the axial direction of the inspection head 16, a feed screw 53 that is arranged parallel to the axis AX of the inspection head 16 and is screwed into the support plate 51, and an electric motor 54 that rotationally drives the feed screw 53. I have. By rotating the feed screw 53 with the electric motor 54, the support plate 51 moves along the rail 52, and the holding cylinder 15 moves in the axial direction of the inspection head 16. Thereby, the inspection light is focused on the inner peripheral surface 100a of the inspection object 100, and the reflected light from the inner peripheral surface 100a is focused on either the first light receiving fiber group 14A or the second light receiving fiber group 14B. The length of the optical path from the lens 17 to the inner peripheral surface 100a through the mirror 18 can be adjusted so as to connect the two.

  Next, the control unit 3 will be described. The control unit 3 controls the operation of each part of the inspection mechanism 2 according to instructions from the arithmetic processing unit 60 as a computer unit that executes inspection process management, measurement result processing, and the like by the surface inspection apparatus 1. Operation control unit 61, signal processing unit 62A that executes predetermined processing on the output signal of PD 12A, signal processing unit 62B that executes predetermined processing on the output signal of PD 12A, and arithmetic processing unit 60 On the other hand, an input unit 63 for a user to input an instruction, an output unit 64 for presenting a measurement result or the like in the arithmetic processing unit 60 to the user, a computer program to be executed by the arithmetic processing unit 60, and measurement And a storage unit 65 for storing data and the like. The arithmetic processing unit 60, the input unit 63, the output unit 64, and the storage unit 65 can be configured using general-purpose computer equipment such as a personal computer. In this case, the input unit 63 is provided with input devices such as a keyboard and a mouse, and the output unit 64 is provided with a monitor device. An output device such as a printer may be added to the output unit 64. The storage unit 65 is a hard disk storage device or a storage device such as a semiconductor storage element capable of storing data. The operation control unit 61 and the signal processing units 62A and 62B may be realized by a hardware control circuit or may be realized by a computer unit.

  Below, a suitable form is illustrated when making the to-be-inspected object 100 the cast product by which the internal peripheral surface 100a was cut. The inspection modes that can be executed by the surface inspection apparatus 1 include a surface defect inspection mode for detecting defects on the surface of the ingot or the like appearing on the inner peripheral surface 100 a as the surface of the inspection object 100, and the surface of the inspection object 100. A foreign matter inspection mode for detecting foreign matter such as chips adhering to the surface as a defect is set, and each inspection mode can be selected in accordance with an instruction from the input unit 63 by the user. The operations of the arithmetic processing unit 60 and the operation control unit 61 are different depending on these inspection modes. First, operations common to the respective modes will be described.

  When inspecting the surface of the inner peripheral surface 100 a of the inspection object 100, the inspection object 100 is arranged coaxially with the inspection head 16. In starting the inspection, the arithmetic processing unit 60 instructs the operation control unit 61 to start an operation necessary for inspecting the inner peripheral surface 100 a of the inspection object 100 in accordance with an instruction from the input unit 63. Upon receiving the instruction, the operation control unit 61 causes the LD 11 to emit light with a predetermined intensity, and moves the inspection head 16 in the axial direction and rotates the motor 35 and the motor 41 around the axis AX at a constant speed. Control the behavior. When the surface defect inspection mode is selected by the user's instruction, the operation control unit 61 focuses the inspection light on the inner peripheral surface 100a, and the reflected light from the inner peripheral surface 100a is the second light receiving fiber. The operation of the motor 54 is controlled so as to focus on the group 14B. On the other hand, when the surface defect inspection mode is selected, the operation control unit 61 focuses the inspection light on the inner peripheral surface 100a, and the reflected light from the inner peripheral surface 100a focuses on the first light receiving fiber group 14A. The operation of the motor 54 is controlled so as to connect the two. By such operation control, the inner peripheral surface 100a is scanned by inspection light from one end to the other end.

  In conjunction with the scanning, the output signal of the PD 12A is sequentially guided to the signal processing unit 62A, and the output signal of the PD 12B is sequentially guided to the signal processing unit 62B. The signal processing unit 62A performs analog signal processing necessary for processing the output signal of the PD 12A by the arithmetic processing unit 60, and A / D-converts the analog signal after the processing with a predetermined number of bits. The digital signal thus output is output to the arithmetic processing unit 60 as a reflected light signal. The A / D conversion performed by the signal processing unit 62A is performed using the pulse train output from the rotary encoder 43 as a sampling clock signal. Thereby, a digital signal having a gradation correlated with the amount of received light (intensity) of the PD 12 while the inspection head 16 rotates by a predetermined angle is generated and output from the signal processing unit 62A. The signal processing unit 62B to which the output signal of the PD 12B is input also functions in the same manner as described above.

  Receiving the reflected light signal from each of the signal processing units 62A and 62B, the arithmetic processing unit 60 stores the signal from the signal processing unit 62A and the signal from the signal processing unit 62B in the storage unit 65 in a state where they can be distinguished from each other. Further, the arithmetic processing unit 60 uses the reflected light signal stored in the storage unit 65 to generate a two-dimensional image in which the inner peripheral surface 100a of the inspected object 100 is developed in a plane, and based on the two-dimensional image, a defect is generated. The inspection result as the determination result is output to the output unit 64.

  Next, a process in which the arithmetic processing unit 60 generates such a two-dimensional image and outputs an inspection result based on the two-dimensional image will be described with reference to FIG. FIG. 3 is a block diagram illustrating the function of the arithmetic processing unit 60. The calculation processing unit 60 functions as the synthesis processing unit 601, the calculation rule setting unit 602, the image generation unit 603, and the determination unit 604 shown in FIG. 3 by executing a predetermined program stored in the storage unit 65. First, the arithmetic processing unit 60 reads the reflected light signal Ps1 based on the output signal of the PD 12A stored in the storage unit 65 and the reflected light signal Ps2 based on the output signal of the PD 12A into the synthesis processing unit 601. Next, the synthesis processing unit 601 combines these signals Ps 1 and Ps 2 in accordance with the calculation rule set by the calculation rule setting unit 602, and outputs the combined signal to the image generation unit 603. The calculation rule setting unit 602 holds a calculation rule corresponding to the above-described surface defect inspection mode and a calculation rule corresponding to the surface foreign matter inspection mode, respectively, and an inspection selected based on an instruction from the input unit 63 Set the operation rule corresponding to the mode.

  The calculation rule held by the calculation rule setting unit 602 takes into account the characteristics (sensitivity characteristics) of the output signals of the PDs 12A and 12B with respect to the property change of the inner peripheral surface 100a of the inspection object 100, in other words, the property change of the reflected light. Is set. First, the calculation rule set in the surface defect inspection mode will be described. In the surface defect inspection mode, a sensitivity characteristic that can distinguish a defect such as a cast hole appearing on the inner peripheral surface 100a of the inspection object 100 and a depression of the inner peripheral surface 100a formed by cutting that should not be a defect is obtained. The operation rule is set as follows. This recess is inevitable when cutting, and is a shallow recess close to so-called chatter that appears on the surface when a tool such as a tool is replaced with a new tool. The depression formed in the inner peripheral surface 100a of the inspection object 100 changes the direction of the reflected light. That is, the depression is considered to be a surface having a certain angle with respect to the irradiation direction (optical axis) of the inspection light.

  FIG. 4 shows the sensitivity characteristic of the detection unit 5 with respect to the change in angle of the reflected light. 4 indicates the output signal of the PD 12A when the angle of the reflected light changes, that is, the sensitivity characteristic of the first light receiving fiber group 14A, and the two-dot chain line L2 indicates the PD 12B when the angle of the reflected light changes. Output signal, that is, the sensitivity characteristic of the second light receiving fiber group 14B, and the solid line L3 indicates the sensitivity characteristic when the output signal of the PD 12A and the output signal of the PD 12B are combined. In FIG. 4, the horizontal axis indicates the angle [deg], and the vertical axis indicates the reflected light intensity. In the surface defect inspection mode, the detection unit 5 is adjusted so that the reflected light is focused on the second light receiving fiber group 14B as described above. For this reason, like the two-dot chain line L2, the sensitivity characteristic of the second light receiving fiber group 14B takes a maximum value at the origin where there is no deviation in the direction of the reflected light, and the sensitivity characteristic that the intensity decreases as the deviation of the reflected light increases. It becomes. On the other hand, the sensitivity characteristic of the first light receiving fiber group 14A is a relationship where the second light receiving fiber group 14B is focused. Show. These sensitivity characteristics include physical configurations such as the distance between the optical fiber groups 14A and 14B, the distance between each of the fiber groups 14A and 14B and the light projecting fiber 13, and the diameter of the light receiving fiber 14 constituting these fiber groups. , Which is unique to the form of the detection unit 5.

  The above-described depression formed in the inner peripheral surface 100a changes the reflected light in a range of about −6 to 6 deg. Therefore, if the detection unit 5 has a substantially flat sensitivity characteristic with respect to an angle change within this range, the intensity of the reflected light received by the detection unit 5 is reduced even when the inspection light is irradiated to the depression. Therefore, it is possible to clearly distinguish the recess from the cast hole. Therefore, in the surface defect inspection mode of this embodiment, the output signal of the PD 12A has a predetermined value so as to have a substantially flat sensitivity characteristic with respect to an angle change within a range of about −6 to 6 deg as shown by a solid line L3 in FIG. A calculation rule is set for adding the product of 0.5 to the output signal of the PD 12B.

  Next, a calculation rule set in the surface foreign matter inspection mode will be described. In the surface foreign matter inspection mode, foreign matter can be detected even when inspection light applied to foreign matter such as chips adhering to the inner peripheral surface 100a of the inspection object 100 is reflected in the same manner as a normal surface without foreign matter. An arithmetic rule is set so that sensitivity characteristics can be obtained. Comparing the case where foreign matters such as chips adhere to the inner peripheral surface 100a and the case where foreign matters are not attached, when the foreign matter is attached, the reflection position of the inspection light becomes closer by the presence of the foreign matter. In other words, the length of the optical path from the lens 17 through the mirror 18 to the inner peripheral surface 100a is shorter when foreign matter is attached than when there is no foreign matter.

  FIG. 5 shows the sensitivity characteristic of the detection unit 5 with respect to the change in distance to the reflection position of the inspection object 100. 5 shows the output signal of the PD 12A when the distance to the reflection position changes, that is, the sensitivity characteristic of the first light receiving fiber group 14A, and the two-dot chain line L2 shows the case where the distance to the reflection position changes. The output signal of the PD 12B, that is, the sensitivity characteristic of the second light receiving fiber group 14B is shown, and the solid line L3 shows the sensitivity characteristic when the output signal of the PD 12A and the output signal of the PD 12B are combined. The horizontal axis in FIG. 5 indicates the positional deviation [mm] between the reference position and the reflection position with the reference position as the origin. A negative sign means that it is close to the detection unit 5 side. The vertical axis in FIG. 5 represents the reflected light intensity. In the surface foreign matter inspection mode, the detection unit 5 is adjusted so that the reflected light is focused on the first light receiving fiber group 14A as described above. For this reason, as indicated by the alternate long and short dash line L1, the sensitivity characteristic of the first light receiving fiber group 14A takes a maximum value at the origin where there is no positional deviation, and becomes a sensitivity characteristic in which the strength decreases as the positional deviation increases. On the other hand, the sensitivity characteristic of the second light receiving fiber group 14B is the same as that obtained by shifting the sensitivity characteristic of the first light receiving fiber group 14A to around -0.5 mm because the focus is on the first light receiving fiber group 14A. It becomes. Since these sensitivity characteristics depend on the physical configuration of the detection unit 5 as described above, they are specific to the form of the detection unit 5.

  Since the average dimension (for example, thickness) of the chips adhering to the inner peripheral surface 100a is about 0.5 mm, when the inspection light is irradiated to the chips adhering to the inner peripheral surface 100a, there is no chips. The reflection position approaches about 0.5 mm compared to the reference position. Therefore, if the detection unit 5 has a sensitivity characteristic having a negative peak that can detect the approach of the reflection position to such an extent, the inspection light irradiated to the foreign matter such as the chips is assumed to be a normal surface free from the foreign matter. Similarly, foreign matter can be detected even when reflected. Therefore, in the surface foreign matter inspection mode of this embodiment, an operation of subtracting the output signal of PD12B from the output signal of PD12A so as to have a sensitivity characteristic having a negative peak at about −0.5 mm as shown by a solid line L3 in FIG. The law is set.

  Each of the arithmetic rules described above constitutes the physical configuration of the detection unit 5, specifically, the distance between the optical fiber groups 14A and 14B, the distance between each of the fiber groups 14A and 14B and the projecting fiber 13, and these fiber groups. This is an example suitable for the size of the diameter of the light receiving fiber 14, and other arithmetic rules can be used to obtain a predetermined sensitivity characteristic.

  As illustrated in FIG. 3, when the image generation unit 603 receives the synthesized signal Ps3 synthesized according to the calculation rule corresponding to each inspection mode from the synthesis processing unit 601, the image generation unit 603 uses the synthesized signal Ps3 to A two-dimensional image in which the inner peripheral surface 100a is developed in a plane is generated, and the two-dimensional image is output to the output unit 64 and the determination unit 604, respectively. The two-dimensional image generated by the image generation unit 603 has, for example, an inner circumference on a plane defined by an orthogonal biaxial coordinate system in which the circumferential direction of the inspection object is the x-axis direction and the axial direction of the inspection head 16 is the y-axis direction. This corresponds to an image obtained by developing the surface 100a. The determination unit 604 determines the presence or absence of a defect exceeding an allowable limit by processing the two-dimensional image obtained from the image generation unit 603 with a predetermined algorithm prepared for each inspection mode, and outputs the determination result to the output unit 64.

  As described above, according to the surface inspection apparatus 1 of the present embodiment, the reflected light signal Ps1 based on the output signal of the PD 12A and the reflected light signal Ps2 based on the output signal of the PD 12B correspond to each inspection mode. By combining according to the above-described calculation rule, the sensitivity characteristic of the detection unit 5 suitable for each inspection mode can be created. Thereby, a plurality of different inspections can be executed by one detection unit 5, and the inspection accuracy in each inspection mode is improved.

  In the above embodiment, the LD 11 is the light source according to the present invention, the PD 12A is the first photoelectric conversion means according to the present invention, the PD 12B is the second photoelectric conversion means according to the present invention, and the first light receiving fiber group 14A is the present. The second light receiving fiber group 14B corresponds to the first light receiving fiber group of the present invention, and the second light receiving fiber group 14B corresponds to the second light receiving fiber group of the present invention.

  However, this invention is not limited to the above form, You may implement with a various form. In the above embodiment, after the output signals from the PDs 12A and 12B are A / D converted, the arithmetic processing unit 60 is made to function so that these digital signals are synthesized according to a predetermined arithmetic rule. Each of the synthesis processing unit 601 and the computation rule setting unit 602 shown in FIG. 63 may be realized by a hardware circuit so that the output signal from the signal is synthesized according to a predetermined computation rule in the state of an analog signal.

  In the above-described embodiment, as shown in FIG. 2, two light receiving fiber groups 14A and 14B having different positional relationships with respect to the light projecting fiber 13 are provided, but a plurality of light receiving fibers are provided on the outer periphery of the second light receiving fiber group 14B. And three light receiving fiber groups may be provided. When three light receiving fiber groups are provided, third photoelectric conversion means for receiving reflected light guided from the outermost third light receiving fiber group may be provided. As a result, the number of variations for combining the signals of the respective photoelectric conversion means increases, so that more various sensitivity characteristics can be given to the detection means.

  Various arithmetic rules set by the arithmetic rule setting unit 602 are assumed. For example, in the surface foreign matter inspection mode described above, the PD 12B signal is subtracted from the PD 12A signal. However, the reflected light is focused on the second light receiving fiber group 12B, and then the PD 12A signal is converted from the PD 12B signal. You may subtract. By doing so, it is possible to obtain a sensitivity characteristic in which the solid line L3 shown in FIG. In this case, it is possible to detect a state in which the reflection position is separated from the reference position by a predetermined distance. As a result, it is possible to detect a recess having a dimension corresponding to a predetermined distance formed on the surface of the inspection object.

  In addition, by setting an arithmetic rule for simply adding the signals of PD12A and PD12B, when a light receiving fiber group having a light receiving area obtained by summing the light receiving areas of the respective fiber groups is provided, that is, the diameter of the light receiving fiber. Sensitivity characteristics that are substantially equivalent to the case of enlarging can be obtained. Note that it is not essential to use both of these signals, and these signals can be used alone as necessary.

  The inspection apparatus 1 described above is applied to the inspection of the cylindrical inner peripheral surface. However, the inspection device 16 is moved in the axial direction without rotating the inspection head 16 and is moved in the direction orthogonal to the axial direction to obtain a planar surface. It can also be used as an inspection apparatus for an inspection object having In the surface foreign matter inspection mode described above, the sensitivity characteristic shown in FIG. 5 is provided for the change in the reflection position, so that the surface inspection apparatus 1 can obtain the roundness of the object to be inspected with a predetermined resolution. It can function as a rotary distance measuring device.

The figure which showed schematic structure of the surface inspection apparatus which concerns on one form of this invention. The plane schematic diagram which showed the front-end | tip part of the light projection fiber and the light reception fiber group hold | maintained with the holding cylinder. The block diagram explaining the function of an arithmetic processing part. The figure which showed the sensitivity characteristic of the detection unit regarding the angle change of reflected light. The figure which showed the sensitivity characteristic of the detection unit regarding the distance change to the reflective position of a to-be-inspected object.

Explanation of symbols

1 Surface inspection device 5 Detection unit (detection means)
11 LD (light source)
12A PD (first photoelectric conversion means)
12B PD (second photoelectric conversion means)
13 Light Emitting Fiber 14 Light Receiving Fiber 14A First Light Receiving Fiber Group (First Light Receiving Fiber Group)
14B Second light receiving fiber group (second light receiving fiber group)
16 Inspection head 30 Linear drive mechanism (linear drive means)
40 Rotation drive mechanism (rotation drive means)
100 Inspected object 100a Inner peripheral surface (surface)
601 Composition processing unit (composition processing means)
602 Calculation rule setting unit (Calculation rule setting means)
AX axis Ps1 first signal Ps2 second signal

Claims (7)

A detection unit configured to irradiate the surface of the inspection object from the light source through the projection fiber and detect the intensity of the reflected light of the inspection light; and based on a detection result of the detection unit, the inspection object In the surface inspection device that inspects the surface of
The detection means includes a first light receiving fiber group including a plurality of light receiving fibers arranged around the light projecting fiber and capable of guiding the reflected light, and the first light receiving fiber as viewed from the light projecting fiber. A second light receiving fiber group comprising a plurality of light receiving fibers arranged outside the group and capable of guiding the reflected light, and a signal corresponding to the intensity of the reflected light guided by the first light receiving fiber group And a first photoelectric conversion means for outputting a signal corresponding to the intensity of the reflected light guided by the second light receiving fiber group. Inspection device.   Combining processing means for combining the first signal output from the first photoelectric conversion means and the second signal output from the second photoelectric conversion means based on a predetermined arithmetic rule; The surface inspection apparatus according to claim 1, further comprising calculation rule setting means for setting the predetermined calculation rule so that sensitivity has a predetermined sensitivity characteristic.   The calculation rule setting unit is configured to set the predetermined calculation rule so that the sensitivity of the detection unit with respect to an angle change of reflected light from the surface of the inspection object has a substantially flat sensitivity characteristic with respect to an angle change within a predetermined range. The surface inspection apparatus according to claim 2, wherein:   The calculation rule setting means sets a calculation rule for adding a value obtained by multiplying the second signal by a predetermined value to the first signal as the predetermined calculation rule. Surface inspection equipment.   The arithmetic rule setting means is configured to set the predetermined sensitivity so that the sensitivity of the detection means related to a change in distance to the reflection position of the inspection object has a sensitivity characteristic having a negative peak when the reflection position is close by a predetermined distance. The surface inspection apparatus according to claim 2, wherein the operation rule is set.   6. The surface inspection apparatus according to claim 5, wherein the calculation rule setting means sets a calculation rule for subtracting the second signal from the first signal as the predetermined calculation rule. A cylindrical inner peripheral surface is provided as the surface of the inspection object,
The detection means irradiates the inspection light from the outer periphery of the inspection head extending in the axial direction toward the inner peripheral surface of the cylindrical body, and moves the inspection head in the axial direction; and the inspection head The surface inspection apparatus according to claim 1, further comprising a rotation driving unit that rotates around an axis.

Images