JP5638195B2 - Inspection head of surface inspection equipment - Google Patents

Description

  The present invention relates to an inspection head of a surface inspection apparatus that inspects the surface of an object to be inspected.

In surface inspection equipment that inspects the inner peripheral surface of a cylindrical object to be inspected for defects, etc., the shape of the inspection head inserted into the object is the same as the inner diameter up to the tip. (For example, refer to Patent Document 1). In the inspection head, the inspection light guided from the light projecting fiber is irradiated to the inner peripheral surface via the condenser lens, and the reflected light is guided to the light receiving fiber via the condenser lens. For this reason, the inner diameter of the inspection head is set in consideration of the lens diameter of the condenser lens.
JP 2007-315798 A

  Since the shape of the inspection head is restricted by the condensing lens, if the inner periphery of the object to be inspected is a deep hole with a large diameter and a deep depth, the optical path is blocked by providing the inspection head from a position close to the condensing lens. The length that can be inserted is secured. On the other hand, in the case of an inspection object having a small diameter, since this inspection head cannot be inserted into the inspection object, it is necessary to replace the inspection head with a small diameter. The small-diameter inspection head is provided with a small-diameter inspection head from a position near the focal point away from the condenser lens in order to reduce the head inner diameter without blocking the optical path in the inspection head. Due to the balance with the condenser lens, the inspection head with a small diameter is shortened, and a shallow hole with a shallow depth can be inserted into the object to be inspected, but a deep hole cannot be accommodated. As described above, the labor of exchanging the inspection head is generated depending on the shape of the inspection object, which is a burden on the operator.

  Therefore, an object of the present invention is to provide an inspection head of a surface inspection apparatus that does not require replacement even when the shape of the inner peripheral surface of the object to be inspected is different.

The inspection head of the surface inspection apparatus of the present invention irradiates the inner peripheral surface (100a) of the inspection object (100) with inspection light and inspects the inner peripheral surface based on the amount of reflected light ( 1. An inspection head (16) applied to 1), wherein the inspection head has a hollow cylindrical shape and is rotated around its axis (AX) and is inserted into the inspection object (21). The sensor head has a first cylindrical part (21a) having a predetermined inner diameter from the front end side and formed to be insertable into the inspection object, and the first cylinder. A second cylindrical part (21b) having an inner diameter larger than the shape part and formed so as to be insertable inside the inspection object, and the first cylindrical part and the second cylinder. In between the shape part, it is formed in a taper shape whose inner diameter gradually increases toward the second tubular part. It is, and the first tapered portion which is insertable formed inside of the object (21d) is provided, focusing lens for focusing said test beam is located outside of the sensor head (17) And passing the inspection light through the sensor head, irradiating the inner peripheral surface with the inspection light from an opening (16a) provided on the outer periphery of the first cylindrical portion, and passing through the condenser lens. The inner diameters of the first cylindrical portion, the second cylindrical portion, and the first tapered portion are set so as not to block the optical path of the inspection light, and the sensor head is more than the second cylindrical portion. A third cylindrical part (21c) having a large inner diameter and formed so as to be insertable inside the inspection object is further provided between the second cylindrical part and the third cylindrical part. And a tapered shape having an inner diameter that gradually increases toward the third cylindrical portion, and A second tapered portion (21e) formed so as to be insertable inside the inspection object is provided, and the first cylindrical portion and the second cylindrical portion are arranged so as not to block the optical path of the inspection light through the condenser lens. The said subject is solved by the internal diameter of a cylindrical part, a said 3rd cylindrical part, a said 1st taper part, and a said 2nd taper part being set .

According to the inspection head of the surface inspection apparatus of the present invention, when inspecting the inner peripheral surface of the inspection object having a small diameter and a shallow hole, by inserting the first cylindrical portion into the inspection object, The inner surface can be inspected. On the other hand, when inspecting the inner peripheral surface of the inspection object having a large diameter and a deep hole, the inner peripheral surface is inspected by inserting the first cylindrical portion and the second cylindrical portion into the inspection object. Can do. Since the second cylindrical portion has a larger inner diameter than the first cylindrical portion, it does not block the optical path of the inspection light by the condensing lens, and even a small-diameter and shallow-hole object to be inspected has a large diameter and a deep depth. Even if it is a hole inspection object, the inner peripheral surface can be inspected without replacing the inspection head. And since the 1st cylindrical part and the 2nd cylindrical part are connected with the taper shape in the 1st taper part, internal reflection of inspection light can also be prevented. Thereby, a highly accurate inspection becomes possible. Further, by providing the third cylindrical portion and the second tapered portion on the main body side with respect to the second cylindrical portion, the sensor head is provided without blocking the optical path even for the optical path of the inspection light near the condenser lens. be able to. By adopting such a stepped shape, a slim sensor head can be provided according to the optical path without blocking the optical path even when the distance from the condenser lens to the focal point becomes long.

  In one form of the inspection head of the present invention, the sensor head may be integrally formed. According to this form, since it is integrally formed, it has sufficient strength and can be used stably.

  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, in the inspection head of the surface inspection apparatus of the present invention, when inspecting the inner peripheral surface of the inspection object having a small diameter and a shallow hole, the first cylindrical portion is disposed inside the inspection object. By inserting it into the inner surface, it is possible to inspect the inner peripheral surface. On the other hand, when inspecting the inner peripheral surface of the inspection object having a large diameter and a deep hole, the inner peripheral surface is inspected by inserting the first cylindrical portion and the second cylindrical portion into the inspection object. Can do. Since the second cylindrical portion has a larger inner diameter than the first cylindrical portion, it does not block the optical path of the inspection light by the condensing lens, and even a small-diameter and shallow-hole object to be inspected has a large diameter and a deep depth. Even if it is a hole inspection object, the inner peripheral surface can be inspected without replacing the inspection head. And since the 1st cylindrical part and the 2nd cylindrical part are connected with the taper shape in the taper part, the internal reflection of test | inspection light can also be prevented. Thereby, a highly accurate inspection becomes possible.

  FIG. 1 shows a schematic configuration of a surface inspection apparatus to which an inspection head according to an embodiment of the present invention is applied. The surface inspection apparatus 1 is an apparatus suitable for inspecting a cylindrical inner peripheral surface 100a provided on an object to be inspected 100, and includes an inspection mechanism 2 for executing inspection, operation control of the inspection mechanism 2, and an inspection mechanism. And a control unit 3 for executing processing of the measurement result by 2 and the like. Further, the inspection mechanism 2 projects the inspection light onto the inspection object 100 and receives the reflected light from the inspection object 100, and a detection unit 5 as a detection means and a predetermined amount to the detection unit 5 And a drive unit 6 for providing the above operations.

  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 reflected light per unit time (reflected light intensity). A photodetector (hereinafter referred to as PD) 12 that outputs a current or voltage signal corresponding to the light, a light projecting fiber 13 that guides the inspection light emitted from the LD 11 toward the inspection object 100, and the inspection object 100. Light-receiving fiber 14 for guiding the reflected light from the PD 12 to the PD 12, a holding cylinder 15 that holds the fibers 13 and 14 in a bundled state, and a hollow-shaft inspection head that is coaxially provided outside the holding cylinder 15 16. The inspection head 16 is rotatably supported on the outer side of the holding cylinder 15.

  At the tip of the holding cylinder 15, the inspection light guided through the light projecting fiber 13 is emitted in the form of a beam along the direction of the axis AX of the inspection head 16 (hereinafter referred to as the axial direction), and the inspection head A lens 17 is provided as a condensing lens for condensing the reflected light traveling in the direction opposite to the inspection light along the axial direction of 16 on the light receiving fiber 14. A mirror 18 is fixed to the tip of the inspection head 16 (the right end in FIG. 1), and a transparent window 16a serving as an opening is provided on the outer periphery of the inspection head 16 so as to face the mirror 18. Yes. The mirror 18 changes the optical path of the inspection light emitted from the lens 17 toward the light transmission window 16 a, and advances the optical path of the reflected light that has entered the inspection head 16 from the light transmission window 16 a toward the lens 17. Change direction.

  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 linear drive means for moving the inspection head 16 in the axial direction. 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 that can move in the axial direction of the inspection head 16 along the rails 32. 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 PD 12 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, a nut 36 is fixed to the slider 33, and a feed screw 34 is screwed into the nut 36. 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 (scanning 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.

  A wall 31a is provided at the front end (right end in FIG. 1) of the base 31, and a through hole 31b coaxial with the inspection head 16 is provided in the wall 31a. A sample piece 37 is attached to the through hole 31b. The sample piece 37 is provided as a sample for determining the operating state of the surface inspection apparatus 1, and a through hole 37 a coaxial with the inspection head 16 is provided on the center line thereof. The through hole 37 a has an inner diameter through which the inspection head 16 can pass, and the inspection head 16 passes through the through hole 37 a and is fed out into the inspection object 100.

  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 an electric motor 41 as a rotation drive source and a transmission mechanism 42 that transmits the rotation of the electric motor 41 to the inspection head 16. For the transmission mechanism 42, a known rotation transmission mechanism such as a belt transmission device or a gear train may be used. In this embodiment, a belt transmission device is 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 with respect to the circumferential direction of the inspection object 100. 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 with the inspection light over the entire surface. Note that the holding cylinder 15 does not rotate when the inspection head 16 rotates. Further, the rotary drive mechanism 40 is provided with a rotary encoder 43 that outputs a pulse signal each time the inspection head 16 rotates by a predetermined unit angle. The number of pulse signals output from the rotary encoder 43 correlates with the rotation amount (rotation angle) of the inspection head 16, and the period of the pulse signals correlates with the rotation speed of the inspection head 16.

  The focus adjusting mechanism 50 is provided as a focus adjusting means for driving the holding cylinder 15 in the direction of the axis AX so that the inspection light is focused on the inner peripheral surface 100a of the inspection object 100. 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 15 and the slider 33 and the support plate 51 of the linear drive mechanism 30. Rail 52 that guides the inspection head 16 in the axial direction, a feed screw 53 that is arranged parallel to the axis AX of the inspection head 16 and screwed into the support plate 51, and an electric motor 54 that rotationally drives the feed screw 53. It has. 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 length of the optical path from the lens 17 through the mirror 18 to the inner peripheral surface 100a can be adjusted so that the inspection light is focused on the inner peripheral surface 100a of the inspection object 100.

  Next, the control unit 3 will be described. The control unit 3 controls the inspection process by the surface inspection apparatus 1, the arithmetic processing unit 60 that executes processing of the measurement result of the detection unit 5, and the operation of each unit of the detection unit 5 in accordance with instructions from the arithmetic processing unit 60. Operation control unit 61, signal processing unit 62 that executes predetermined processing on the output signal of PD 12, input unit 63 for a user to input an instruction to arithmetic processing unit 60, and arithmetic processing unit 60 Are provided with an output unit 64 for presenting the examination results and the like processed by the user, a computer program to be executed by the arithmetic processing unit 60, and a storage unit 65 for storing measured 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 a general-purpose computer device 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 unit 62 may be realized by a hardware control circuit or may be realized by a computer unit.

  When inspecting the surface of the inner peripheral surface 100a of the inspection object 100, each of the arithmetic processing unit 60, the operation control unit 61, and the signal processing unit 62 operates as follows. In this case, 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 the operations of the motors 35 and 41 so that the inspection head 16 moves in the axial direction and rotates around the axis AX at a constant speed. To control. Further, the operation control unit 61 controls the operation of the motor 54 so that the inspection light is focused on the inner peripheral surface 100a as the surface to be inspected. By such operation control, the inner peripheral surface 100a is scanned by inspection light from one end to the other end. The driving of the inspection head 16 in the axial direction may be a feeding operation at a constant speed, or an intermittent feeding operation that moves by a predetermined pitch every time the inspection head 16 rotates.

  The output signal of the PD 12 is sequentially guided to the signal processing unit 62 in conjunction with the above-described scanning of the inner peripheral surface 100a. The signal processing unit 62 performs analog signal processing necessary for processing the output signal of the PD 12 by the arithmetic processing unit 60, and further performs A / D conversion on the analog signal after the processing with a predetermined number of bits, The obtained digital signal is output to the arithmetic processing unit 60 as a reflected light signal. The signal processing executed by the arithmetic processing unit 60 includes various processes such as a process of nonlinearly amplifying the output signal so as to enlarge the brightness difference of the reflected light detected by the PD 12 and a process of removing a noise component from the output signal. May be used as appropriate. Fast Fourier transform processing, inverse Fourier transform processing, and the like can be appropriately combined. The A / D conversion by the signal processing unit 62 is performed using a pulse train output from the rotary encoder 43 as a sampling clock signal. As a result, a digital signal having a gradation correlated with the amount of light received by the PD 12 while the inspection head 16 rotates by a predetermined angle is generated and output from the signal processing unit 62.

  The arithmetic processing unit 60 that has received the reflected light signal from the signal processing unit 62 stores the received signal in the storage unit 65. 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 inspection object 100 is developed in a plane. In the two-dimensional image, for example, the inner peripheral surface 100a is developed on a plane defined by an orthogonal two-axis coordinate system in which the circumferential direction of the inspection object 100 is the x-axis direction and the axial direction of the inspection head 16 is the y-axis direction. Corresponds to an image. Note that, when generating a two-dimensional image in the arithmetic processing unit 60, a two-dimensional image in which defects to be detected are emphasized by performing edge processing, binarization processing, etc. on the original image obtained from the reflected light signal. May be generated. Then, the arithmetic processing unit 60 determines whether or not a defect exceeding an allowable limit exists on the inner peripheral surface 100a by processing the obtained image with a predetermined algorithm, and outputs the determination result to the output unit. 64.

  FIG. 2 shows an enlarged view of the inspection head 16. The inspection head 16 includes a sensor head 21 that is inserted into the inspection object 100 and a main body side head 22 that fixes the sensor head 21. The sensor head 21 includes a first tubular portion 21a having a small diameter and a straight tube shape from the front end side, a second tubular portion 21b having a larger inner diameter than the first tubular portion 21a, and a second tubular portion 21b. The 3rd cylindrical part 21c with a large internal diameter, the 1st taper part 21d which connects between the 1st cylindrical part 21a and the 2nd cylindrical part 21b, the 2nd cylindrical part 21b, and the 3rd cylindrical part 21c And a second taper portion 21e that connects the two. The sensor head 21 has a tubular shape and is integrally formed of a material such as metal. The 1st cylindrical part 21a, the 2nd cylindrical part 21b, and the 3rd cylindrical part 21c are arrange | positioned coaxially centering on the axis line AX. The third cylindrical portion 21 c is fixed to the main body side head 22. In addition, the mirror 18 mentioned above is fixed to the front-end | tip part of the 1st cylindrical part 21a, and the transparent window 16a is provided in the outer periphery of the 1st cylindrical part 21a so that the mirror may be opposed. 21 d of 1st taper parts are formed in the taper shape so that an internal diameter may become large gradually toward the 2nd cylindrical part 21b between the 1st cylindrical part 21a and the 2nd cylindrical part 21b. The second tapered portion 21e has the same configuration. By adopting such a tapered shape, internal reflection of inspection light can be prevented, and high-precision inspection can be performed.

The distance between the inner peripheral surface 100a of the object 100 to be measured and the lens 17 is a (in FIG. 2, the distance between the lens 17 and the transparent window 16a is a1, and the distance between the transparent window 16a and the inner peripheral surface 100a is a. If the distance is a2 and a = a1 + a2, and the diameter of the lens 17 is D, the limitation on the taper angle θ of each of the taper portions 21d and 21e is
tan θ = D / 2a
It becomes. The taper angle θ is an angle formed by a straight line parallel to the tapered surfaces of the taper portions 21d and 21e and a straight line parallel to the axis AX. The shape of the sensor head 21 is set so as not to block the optical path of inspection light and reflected light passing through the lens 17. For this reason, the first cylindrical portion 21a on the distal end side of the sensor head 21 has a small diameter, and the third cylindrical portion 21c on the main body side has a large diameter. The length of each cylindrical part 21a-21c is set to the length by which the internal diameter calculated | required based on the desired outer diameter of each cylindrical part 21a-21c does not interfere with an optical path.

  The operation of the inspection head 16 will be described. FIG. 3 is a diagram illustrating scanning of the inner peripheral surface 101a of the inspection object 101 having a deep hole with a deep inner depth and a large inner diameter. Even inside the inspection object 101 having such a deep hole and a large diameter, the third cylindrical portion 21c of the sensor head 21 can be inserted, and the inner peripheral surface 101a can be scanned. FIG. 4 is a diagram for explaining scanning of the inner peripheral surface 102a of the inspection object 102 having a shallow hole with a shallow inner depth and a small inner diameter. In the case of the inspection object 102 having a shallow hole and a small diameter, a conventional large-diameter straight sensor head cannot be inserted into the inspection object 102, and the sensor head can be replaced with a small-diameter straight object. I must. In the inspection head 16 of this embodiment, since the first cylindrical portion 21a has a small diameter, the first cylindrical portion 21a can be inserted into the inspection object 102 without replacing the inspection head 16. As an example, the inspection object 100 is inspected having an inner diameter of 4 to 8 [mm] and an inner depth of 20 to 60 [mm]. That is, it is assumed that the small diameter is about 4 [mm], the large diameter is about 8 [mm], the shallow hole is about 20 [mm], and the deep hole is about 60 [mm].

  FIG. 5 is a diagram for explaining scanning of the inner peripheral surface 103a of the inspection object 103 which is a deep hole and has a step inside, and which has a small diameter on the back side. In such an inspected object 103 having a step inside, a large-diameter straight-shaped sensor head cannot be inserted into the small-diameter portion on the back side, while a small-diameter straight-shaped sensor head is short in length. The back side cannot be scanned. In the inspection head 16 of this embodiment, the length of the sensor head 21 is the same as that of the conventional large-diameter straight-shaped sensor head, and the first cylindrical portion 21a has a small diameter. Even if there is, it can be inserted.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, in this embodiment, the sensor head 21 having the three cylindrical portions 21a to 21c and the two tapered portions 21d and 21e has been described, but the present invention is not limited to this. For example, a sensor head having two cylindrical portions and one tapered portion may be used. Or the sensor head which has four or more cylindrical parts and three or more taper parts may be sufficient. The number of the cylindrical portions and the tapered portions may be appropriately provided according to the distance from the lens 17 to the inspection surface and the optical path. The material of the sensor head 21 is not limited to metal, and may be glass, resin, or the like as an example.

The figure which shows schematic structure of the surface inspection apparatus with which the test | inspection head which concerns on one form of this invention was applied. The enlarged view of an inspection head. The figure explaining the scanning of the internal peripheral surface of a to-be-tested object which is a deep hole and has a large diameter. The figure explaining the scanning of the inner peripheral surface of a to-be-inspected object with a shallow hole and a small diameter. The figure explaining the scanning of the internal peripheral surface of the to-be-inspected object which has a level | step difference inside and is a deep hole, and becomes a small diameter on the back side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface inspection apparatus 16 Inspection head 16a Translucent window (opening part)
17 Lens (Condenser lens)
21 Sensor head 21a 1st cylindrical part 21b 2nd cylindrical part 21d Tapered part 100 Inspected object 100a Inner peripheral surface AX Axis line

Claims (2)

An inspection head applied to a surface inspection apparatus that irradiates an inner peripheral surface of an object to be inspected with inspection light and inspects the inner peripheral surface based on the amount of reflected light,
The inspection head has a sensor head that is inserted into the inspection object while being rotated around its axis in a hollow cylindrical shape,
The sensor head has a first cylindrical portion that has a predetermined inner diameter from the front end side and that can be inserted into the inspection object, and an inner diameter that is larger than the first cylindrical portion. And a second cylindrical part formed so as to be insertable inside the inspection object, and between the first cylindrical part and the second cylindrical part, the second cylindrical part is provided. A tapered portion having an inner diameter that gradually increases toward the cylindrical portion, and a first tapered portion that is formed so as to be insertable inside the inspection object;
The inspection light is allowed to pass through the sensor head via a condensing lens that is located outside the sensor head and condenses the inspection light, and the opening is provided on the outer periphery of the first cylindrical portion. Irradiate the inner peripheral surface with the inspection light,
Inner diameters of the first cylindrical portion, the second cylindrical portion, and the first tapered portion are set so as not to block the optical path of the inspection light via the condenser lens ,
The sensor head further includes a third cylindrical portion having an inner diameter larger than that of the second cylindrical portion and formed to be insertable into the inspection object, and the second cylindrical portion and the second cylindrical portion, A second tapered portion formed between the third cylindrical portion and a tapered shape having an inner diameter that gradually increases toward the third cylindrical portion, and that can be inserted into the inspection object. Is provided,
The first cylindrical portion, the second cylindrical portion, the third cylindrical portion, the first tapered portion, and the second tapered portion so as not to block the optical path of the inspection light through the condenser lens. An inspection head of a surface inspection apparatus, wherein the inner diameter of the surface inspection apparatus is set . The inspection head according to claim 1 , wherein the sensor head is integrally formed.

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