JP6694701B2 - In-line inspection device and inspection method - Google Patents

Description

  The present invention relates to an in-line inspection device and inspection method for non-destructively inspecting a work on a processing line. More specifically, in the machining line of the workpiece, not only the concave and convex shapes before machining but also the surface condition thereof can be more accurately discriminated, and whether or not the machining is accurately performed after machining, for example, from the reference position to the hole. It is suitable for an in-line inspection device and an inspection method for obtaining the depth.

  There are processing lines for cylinder blocks such as castings in automobile engine manufacturing plants, and in the manufacturing process of cylinder blocks, not only the uneven shape but also the surface condition can be properly identified and processed on the processing line, in-line. More precise inspection is required such as what has been done.

  The cylinder block is always machined to have holes and threads.For the holes and threads, chips and foreign matter remain, defects due to machining and material problems (scratches on the surface, nests of castings), Inspection of hole size and shape is required. In particular, as for the size and shape of the hole, it can be drilled straight, there is no eccentricity, there is no unprocessed part, whether the tip of the drill is missing as a residue and remains in the hole, etc. However, it is desired to inspect 100% automatically in-line.

  In order to automate the inspection of the machining hole of the cylinder block, a flaw detection probe is set in place of the tool attached to the NC device for machining the hole, and the flaw detection probe is driven by the NC device. It is known that the shaft is displaced in the axial direction while rotating, and is described in Patent Document 1, for example.

  Also, to ensure 100% inspection on the line for the presence or absence of clogging of water holes caused by the casting of the cylinder block, insert the inserts into the water holes and move them forward, etc. Inspect for the presence of. That is, if the water hole is clogged, when the insert body comes into contact with the clogged portion, the insert body is relatively displaced in the direction opposite to the moving direction of the entire apparatus, and this displacement is caused by a proximity switch or the like. It is known to detect the presence of clogging by detecting with a detection means, and it is described in Patent Document 2, for example.

  Further, in a machined hole inspection apparatus and machined hole inspection method for inspecting a workpiece having a machined hole, an inspection pin having a tapered tip with respect to the machined hole is advanced and retracted to reduce the amount of the inspection pin entering the machined hole. Based on this, it is known to judge the quality of the machined hole, which is described in Patent Document 3, for example.

JP, 2011-75281, A JP, 8-145852, A JP, 2009-262237, A

  However, in the above-mentioned conventional technology, the method of measuring a workpiece by a contact method during the assembly or processing transfer line is not only difficult to detect with high accuracy due to displacement of the workpiece and the like, but also failure and damage due to impact may occur. There is a fear.

  Further, in the case of using an optical TV camera or a displacement type laser sensor, it is affected by the environment in which the transfer line is placed. For example, a machine tool such as a machining center that has an automatic tool change function and performs different types of machining such as milling, boring, drilling, tapping, etc. according to the purpose needs to identify the model immediately before machining. In the formula, light and laser are diffused in an environment of fine particles of oil mist and dust, and accurate measurement is difficult.

  Furthermore, when using an eddy current type displacement sensor that uses a high frequency magnetic field that is said to be resistant to dust, water, oil, etc., the accuracy and response speed are fast, but the measurable distance is short at a few mm, so Not suitable for use in transport lines.

  Further, an ultrasonic displacement sensor using ultrasonic waves as a medium has a long measuring distance and is suitable for use in a conveyance line. However, the accuracy is low compared to other methods and the size of the measurement surface must be increased just by using it, and it is difficult to find scratches or cracks or the hole depth from the reference position as the surface condition of the workpiece. Met.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and even when a plurality of types of work flow in a transport line of assembly or processing in a mixed manner, the uneven shape of the work in-line, such as scratches and cracks as the surface state It is to determine whether or not the processing has been accurately performed after an abnormality or after the processing. In particular, in a cylinder block transfer line in an automobile engine manufacturing plant, the hole depth, the bending of the hole, and other abnormalities are inspected from a reference position to improve reliability.

  In order to achieve the above object, the present invention is an in-line inspection device for nondestructively inspecting a work on a processing line, by transmitting ultrasonic waves toward a reference surface or a measurement surface provided at a predetermined position of the work. A master sensor that receives a reflected wave and measures the time from transmission to reception, and when the master sensor transmits an ultrasonic wave toward the reference surface, transmits an ultrasonic wave toward the measurement surface and returns the reflected wave. Is received, the time from transmission to reception is measured, and when the master sensor transmits an ultrasonic wave toward the measurement surface, the ultrasonic wave is transmitted toward the reference surface and a reflected wave is received. A slave sensor that measures the time until reception is provided, and the state of the measurement surface is determined using the difference between the values measured by the master sensor and the slave sensor.

  Since the state of the measurement surface is determined using the difference between the values measured by the master sensor and the slave sensor, the temperature, oil mist, dust, etc., in the measurement of the distance from the master sensor and slave sensor to the measurement surface of the workpiece The effects can be offset. Therefore, even in an environment such as a production line of a cylinder block, it is possible to accurately determine whether the quality is good or not, with a sufficient working distance that does not hinder machining.

  Further, the present invention, in an in-line inspection apparatus for nondestructively inspecting a work on a processing line, a master transmission unit for transmitting an ultrasonic wave toward a reference surface or a measurement surface provided at a predetermined position of the work, and its A master receiving unit that receives a reflected wave, a master sensor having a master time measuring unit that measures the time from transmission to reception, and a slave transmitting unit that transmits an ultrasonic wave toward the measurement surface or the reference surface, A slave receiving unit that receives the reflected wave, and a slave time measuring unit that measures the time from transmission to reception, and when the master sensor transmits an ultrasonic wave toward the reference surface, to the measurement surface When transmitting the ultrasonic wave, when the master sensor transmits the ultrasonic wave toward the measurement surface, a slave sensor that transmits the ultrasonic wave toward the reference surface, the master time measuring unit and the slave time measuring unit And a discriminating unit that discriminates the state of the measurement surface by using the difference between the values measured by and.

  Furthermore, in the above-mentioned thing, it is desirable that the transmission of the ultrasonic wave is alternately performed by the master sensor and the slave sensor.

  As a result, it is possible to prevent the ultrasonic waves from interfering with each other between the master sensor and the slave sensor.

Further, in the above, it is preferable that the master sensor generate a clock signal that serves as a reference time for transmitting the ultrasonic wave, and the slave sensor transmit the ultrasonic wave in synchronization with the clock signal.
Even if the measurement is repeated a number of times, it is possible to avoid interference for a long time without shifting the transmission timing of ultrasonic waves.

  Furthermore, in the above, the master work having the reference surface and the measurement surface serving as a reference, and the difference value obtained by measuring the reference surface and the measurement surface by the master sensor and the slave sensor using the master work are registered. It is preferable that the quality of the processing is determined by including a determination data table and comparing the difference value obtained by measuring the reference surface and the measurement surface by the master sensor and the slave sensor on the processing line.

  As a result, it is possible to inspect for machining defects such as chips and foreign substances remaining on the machined holes and screws, defects due to problems with the material after processing (materials such as scratches on the surface and casting), hole size and shape, etc. It can be done more accurately.

Further, in the above, it is preferable that the master work is provided with a hole having a predetermined shape as the measurement surface.
The quality of the hole depth after processing can be more accurately determined.

Furthermore, in the above-mentioned thing, it is desirable that the masterwork has a surface condition that is normal as the measurement surface.
Regardless of before and after processing, it is possible to identify defects such as surface scratches and casting cavities.

Furthermore, in the above, it is preferable that the oscillation frequency of the ultrasonic wave is 200 to 400 kHz.
As a result, the beam size of ultrasonic waves can be reduced, and a measurement surface with a small area can be identified.

Furthermore, in the above-mentioned thing, it is desirable that the beam size of the transmitted ultrasonic wave in the said identification part be 15-20 mm.
As a result, even if the casting has a complicated shape such as a cylinder block, the measurement does not become an obstacle.

Furthermore, in the above-mentioned thing, it is desirable that the distance from the master sensor and the slave sensor to the identification unit is 150 to 200 mm.
Since it is not necessary to bring the sensors close to each other in the cylinder block manufacturing line, the position control for stopping the work becomes easy, and the sensor position does not hinder the processing.

Further, in the above, it is preferable that the work is a cylinder block and the processing line is used for processing the cylinder block.
In the cylinder block manufacturing process, it can be made suitable in terms of environment, accuracy, measurement area, and the like.

  According to the present invention, since the state of the measurement surface is determined using the difference between the values measured by the master sensor and the slave sensor, the temperature in the measurement of the distance from the master sensor and the slave sensor to the measurement surface of the workpiece, The effects of oil mist and dust can be offset. Therefore, even in an environment such as a production line of a cylinder block, it is possible to make an accurate determination with a sufficient working distance that does not hinder machining. In particular, reliability can be improved in a cylinder block processing line in an automobile engine manufacturing plant.

Configuration diagram showing a case where a work identification device according to an embodiment of the present invention is applied to a machine tool or the like Block diagram showing a determination process in one embodiment Explanatory drawing which shows the measurement surface shape (hole processing) of a workpiece | work and processing in one embodiment. Explanatory drawing showing allocation (mastering) of measurement surface shape and work number in one embodiment Explanatory drawing showing the quality judgment of processing in one embodiment Graph showing the relationship between the beam spot diameter of the ultrasonic displacement sensor, the oscillation frequency and the distance A graph showing the relationship between the energy density of the ultrasonic displacement sensor and the oscillation frequency and distance. A graph showing the relationship between the beam spot diameter, the oscillation frequency, and the distance of the ultrasonic displacement sensor according to the embodiment. Graph showing output value vs. time in a conventional ultrasonic displacement sensor Graph showing output value vs. time in ultrasonic displacement sensor in one embodiment Explanatory drawing of the discrimination effect with respect to the temperature change in the ultrasonic displacement sensor in one embodiment. Explanatory drawing which shows the measurement interval in the ultrasonic displacement sensor in one embodiment. Explanatory drawing which shows the process at the time of processing the hole inclining in one Embodiment. Explanatory drawing which shows the process when a residue is left in the hole in one embodiment.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  In the production of automobiles, in order to meet the diversifying consumer needs for automobiles, multi-model small-volume production is desired. Under such multi-model, low-volume production, from the perspectives of production efficiency, total line length, incidental equipment costs, and line operating rate, it is possible to support multiple models rather than assembling products on a dedicated line for each model. It is preferable to assemble the product in a multi-model mixing line that can be done. In addition, there is a processing line for a cylinder block such as a casting in an automobile engine manufacturing plant, and in the manufacturing process of the cylinder block, not only the uneven shape but also the surface state can be determined and processed in the processing line, that is, in-line. More precise inspections such as discrimination of what was done properly are required. The cylinder block serves as the foundation (base) for incorporating cylinders, cylinder heads, crankshafts, and other parts as well as cylinders.

  Further, the cylinder block is a part that contacts the heart of the engine, and the cylinder head, engine mount, and various accessories are attached by a strong bolt connection. Further, a piston is inserted in the cylinder, a crankshaft is mounted on the lower side of the block, a cylinder head is mounted on the cylinder, and an intake / exhaust system and a valve drive system are mounted. Further, the cylinder block has a cooling water passage through which cooling water circulates and an oil passage for distributing oil to each part. If the cooling water or oil is not properly managed in the oil passage, dirt will accumulate and cause overheating or seizure.

  Therefore, the cylinder block is always machined to have holes and threads, and the holes and screws have residual chips and foreign matter, defects after machining and material problems (surface scratches, casting cavities). ), Hole size and shape, etc. are in-line, and all are automatically inspected. Especially, as for the size and shape of the hole, make sure that the hole can be drilled straight and that there is no eccentricity, there are no unprocessed parts, and that the tip of the drill is missing and remains in the hole. ..

  FIG. 1 is a configuration diagram in which a work identification device according to an embodiment of the present invention is applied to a machining center that is a machine tool. Reference numeral 6 denotes a work, which is a cylinder block in which a plurality of pistons are housed and a crankshaft is attached to a lower crankcase portion.

  The cylinder block is generally made of cast iron or cast aluminum alloy, and various types of workpieces 6 are mixed into the transfer line. 2. Description of the Related Art There are cylinder block transfer lines in automobile engine manufacturing plants, and in many cases, a plurality of types of cylinder blocks are mixed and flow as works on this transfer line.

  And as the processed holes, the size and inclination of the holes, the shape of eccentricity, the surface scratches and burrs, the burrows of casting parts, chips and residues are directly connected to the quality of the finished product, and inline Perform 100% automatic inspection. Processing of the cylinder block is usually performed in a machining center.

  A machining center is a numerically controlled machine tool that performs various processing such as milling, drilling, boring, tapping, etc. without changing the attachment of the work (workpiece). For example, 5 in FIG. 1 is a machine tool for drilling. Is. Further, the tool magazine stores a large number of cutting tools, performs automatic machining according to a computer numerical control command, and has an automatic tool changer. Further, there are known ones in which a work table can be rotated at high speed and a turning tool can be attached to a spindle to perform turning, a grinding wheel can be used instead of a milling tool, and a probe for dimension measurement can be mounted. Since the main purpose is machining, therefore, the environment in which the machining center is installed contains fine particles of oil mist and dust, and ultrasonic displacement sensors are used to inspect castings such as cylinder blocks among them. Is desirable.

  The cylinder block that is the work 6 is placed on the transfer line, and when the machine tool controller 4 instructs the movement of the work 6 to the position where it can be processed, as shown by the broken line, the machine tool controller 4 performs the processing instruction depending on the model of the work 6. Go to Machine 5. The machining instruction includes, for example, the size and position of the hole as the specifications for drilling, and the rotation speed as the processing conditions.

  When the machining of the work 6 is completed, the machine tool controller 4 sends the work 6 in the direction of arrow A and stops it at a predetermined position. The master sensor 1 and the slave sensor 2 are ultrasonic displacement sensors, and when the work 6 is stopped, the master sensor 1 is connected to a reference surface 7 (see FIG. 3) provided at a predetermined position of the work 6 as a slave sensor. A measurement surface 8 (see FIG. 3), for example, transmits ultrasonic waves toward the opening of a hole, receives reflected waves, and measures distances.

  The master sensor 1 includes a master transmission unit that transmits an ultrasonic wave toward a reference surface 7 or a measurement surface 8 provided at a predetermined position of the work 6, a master reception unit that receives the reflected wave, and a transmission from reception to reception. It has a master time measuring unit for measuring time.

  The slave sensor 2 includes a slave transmission unit that transmits ultrasonic waves toward the measurement surface 8 or the reference surface 7, a slave reception unit that receives the reflected wave, and a slave time measurement unit that measures the time from transmission to reception. have.

  Reference numeral 3 denotes a sensor unit that performs measurement by the master sensor 1 and the slave sensor 2 and determines the measurement result. The sensor unit 3 receives a measurement start instruction from the machine tool controller 4 and transmits the measurement result.

  Here, since the ultrasonic waves are excellent in focusing and directivity and are dense waves of air, the influence of scattering by fine particles in the air is smaller than that of the optical type, and the oil mist and dust of the machine tool 5 are installed. Stable measurement is possible even in the environment. Moreover, if ultrasonic waves are used, measurement of all materials including metal, wood, glass, rubber, etc., powders, liquids, etc., as the measurement object (workpiece 6) is non-contact, long distance from the workpiece 6 and several hundred mm. Can be done apart.

  The ultrasonic displacement sensor detects the presence or absence of the target object and the distance to the target object by transmitting ultrasonic waves to the target object by the wave transmitter and receiving the reflected wave by the wave receiver. An ultrasonic element is used for transmitting and receiving ultrasonic waves.The ultrasonic element is an element that applies electric energy to generate ultrasonic waves or converts ultrasonic vibration energy into an electric signal. The barium titanate oscillator used is used.

  The piezoelectric element vibrates when an AC voltage is applied, has a specific frequency, and efficiently oscillates when an AC voltage having the same frequency as that frequency is applied. Generally, 40 kHz is often used, and low frequency is used to measure a long distance and high frequency is used to measure a short distance accurately.

  Further, the ultrasonic displacement sensor can measure all materials such as metal, wood, glass, rubber, powder, and liquid, and since it is non-contact, there is no problem of influence of viscosity and corrosion. It has the features of being able to detect long distances, not obstructing moving objects on the transfer line, and being able to perform stable level measurement in adverse environments.

  Further, the ultrasonic displacement sensor measures the length by measuring the time from the transmission of ultrasonic waves to the reception thereof. Therefore, since the ultrasonic displacement sensor does not change the arrival time even if the surface roughness of the object to be measured is large or the strength is changed, stable measurement is possible. In particular, when the work 6 is a cast cylinder block, this advantage can be utilized, and even if the cylinder block is heated, it is not affected.

  Also, the speed of sound in the air changes depending on the temperature, and the measurement result of the ultrasonic displacement sensor is affected by the change in the atmosphere. Therefore, each of the master sensor 1 and the slave sensor 2 is an ultrasonic displacement sensor that measures the time from transmission to reception, and the sensor unit 3 uses the difference between the measurement values of the pair of master sensor 1 and slave sensor 2. Make a distinction.

  That is, when the master sensor 1 transmits ultrasonic waves toward the reference surface 7, the slave sensor 2 transmits ultrasonic waves to the measuring unit 8 and when the master sensor 1 transmits ultrasonic waves toward the measuring surface 8. , Ultrasonic waves are transmitted toward the reference plane 7. Then, it has a discriminating unit that discriminates the state of the measurement surface 8 by using the difference between the values measured by the master time measuring unit and the slave time measuring unit.

  Since the measurement is performed by using the difference between the values measured by the master sensor 1 and the slave sensor 2, the influence of the temperature, oil mist, dust, etc. on the distance from the master sensor 1 and the slave sensor 2 to the reference position of the work 6. Can be offset. Therefore, even in an environment such as a production line of a cylinder block, it is possible to perform the measurement accurately with a sufficient working distance that does not hinder the processing.

  FIG. 2 is a block diagram showing the determination process, and the master sensor 1 and the slave sensor 2 are each configured to measure the distance to the work 6. FIG. 3 shows a measurement surface of the work 6, where 7 is a reference surface and 8 is a measurement surface. Then, as shown in the drawing, the reference surface 7 is a surface facing the master sensor 1, the measurement surface 8 is facing the slave sensor 2, and the depth of the hole 9 is measured. In the measurement, the measurement surfaces need to face each other at the stop position of the workpiece 6 as shown in FIG. 3, and the size of the measurement surface is determined by the stop position accuracy and the beam size of the ultrasonic displacement sensor. However, since the cylinder block is a casting, a smaller measurement area is required.

  Further, by taking the difference between the measured values of the master sensor 1 and the slave sensor 2, the process of measuring the length between the sensor and the work 6 is canceled, and the distance measurement from the reference surface 7 to the measurement surface 8 of the hole 9 is limited. If two ultrasonic displacement sensors are simply used side by side, the ultrasonic waves interfere with each other to cause a measurement error, but the master sensor 1 and the slave sensor 2 alternately oscillate the ultrasonic waves so as to avoid the interference. Therefore, it is possible to prevent the ultrasonic waves from interfering with each other between the master sensor 1 and the slave sensor 2.

  The master sensor 1 and the slave sensor 2 have the same configuration, have ultrasonic elements 31 and 32, respectively, and are switched by the CPUs 33 and 34 to perform transmission and reception. The memories 35 and 36 temporarily store the measurement data, and the CPUs 33 and 34 control the storage and reading. The master sensor 1 and the slave sensor 2 are connected to each other, and the ultrasonic element 32 of the slave sensor 2 oscillates in synchronization with the clock signal generated by the master sensor 1. The measurement data of the slave sensor 2 is transmitted to the CPU 33 of the master sensor 1. As a result, even if the measurement is repeated many times, it is possible to avoid interference for a long time without shifting the transmission timing of ultrasonic waves.

  The CPU 33 of the master sensor 1 is connected to the machine tool controller 4, the machine tool controller 4 gives an instruction to start the measurement, and the determination result indicating the quality of machining is transmitted from the CPU 33 to the machine tool controller 4. After receiving the determination result, the machine tool controller 4 moves or stops the next work 6 according to the determination result.

  In order to avoid interference, the master sensor 1 and the slave sensor 2 generate a clock signal serving as a reference time for transmitting ultrasonic waves by the master sensor 1, and the slave sensor 2 synchronizes with the generated clock signal on the master sensor 1 side. The master sensor 1 and the slave sensor 2 alternately transmit so as to transmit ultrasonic waves, and the transmission interval is set to a time sufficient to eliminate reverberation due to reflected waves from the work. Since the reverberation due to the reflected wave depends on the operating distance between the master sensor 1, the slave sensor 2 and the work 6, the operating distance is determined by setting the transmission interval.

  The measurement is started by first transmitting the ultrasonic element 31 of the master sensor 1 and then transmitting the ultrasonic element 32 of the slave sensor 2. After setting this as one set and repeating a predetermined number of sets, the transmission is stopped. The measurement surface of the work 6 is provided with a reference surface 7 adjacent to the measurement surface 8 as shown in FIG. In the example of FIG. 3, the distance from the master sensor 1 to the work 6 is 200 mm as an operation distance, the distance from the slave sensor 2 to the measurement surface 8 is 203 mm, the depth of the hole 9 is 3 mm, and the master sensor 1 side is It is convex toward the 3 mm ultrasonic displacement sensor side as compared to the slave sensor 2 side.

  The time until the ultrasonic wave 31 of the master sensor 1 is transmitted and the reflected wave from the concave portion of the work 6 reaches the master sensor 1 is counted as measurement data and stored in the memory 35. Next, the ultrasonic element 32 of the slave sensor 2 is transmitted with the timing shifted so as not to interfere with each other, and the time until the reflected wave returns to the slave sensor 2 is counted and stored in the memory 36.

  After the transmission is stopped, the slave sensor 2 outputs the stored measurement data to the master sensor 1. The master sensor 1 calculates the difference between its own measurement data stored in the memory 35 and the measurement data output from the slave sensor 2. Then, the CPU 33 of the master sensor 1 determines that the distance from the reference surface 7 to the measurement surface 8 as the measurement surface, that is, the depth of the hole 9 is 3 mm.

  FIG. 4 shows a procedure of pass / fail judgment when the depth of the hole 9 is different for each model. First, a work number is given to each model, the depth of the hole 9 is assigned to each model, and the discrimination standard is stored in the memory 35 (mastering mode). The pass / fail judgment may be made directly by the value measured as the depth of the hole 9, but it is desirable to calibrate separately by using the standard separately processed as follows.

  For the cylinder block actually mounted on the transfer line to be measured, separately prepare the required types of master work 11 for the depth of the hole 9 serving as the reference. Set it in slave sensor 2. The master work 11 corresponding to the work number 1 is measured, and the read difference value between the master sensor 1 and the slave sensor 2 is made to correspond to the work number 1 and shown in the discrimination data table 12 as a reference for the quality judgment. Register as work number 1 as shown in. The discrimination data table 12 is stored in the memory 35 of the master sensor 1 as a table structure.

  FIG. 5 shows the pass / fail determination, which is a pass / fail determination mode in which the cylinder block (workpiece 6) placed on the transfer line is measured. The workpiece 6 having the workpiece number determined in advance is measured as described above, and the difference value between the measured master sensor 1 and the slave sensor 2 is compared with the determination data table 12 and stored. It is determined whether or not it matches the depth value of the hole 9 in the work number. When they match, the machine tool controller 4 is informed that the machining is normally performed. The machine tool controller 4 executes a machining instruction or the like according to the next work 6.

  Normally, not only the measured value of ultrasonic waves is affected by the temperature, but also the beam size of the ultrasonic waves tends to spread with respect to the workpiece 6 to be measured. As a result, the measurement area must be increased, and in the case of a cylinder block, the surface shape and roughness of the casting have a large effect, making practical use difficult. Further, the beam size can be reduced by providing an ultrasonic horn that is a reflector for focusing and emitting or receiving ultrasonic waves in a certain direction. However, in the case of the reflector, only the ultrasonic waves traveling straight from the object to be measured can be received. Therefore, it is desirable to utilize the fact that the ultrasonic waves have a straightness that increases in proportion to the height of the frequency and the beam size can be reduced.

  Further, when the frequency is the same and the transducer size is different, the directivity becomes sharp when the transducer size is large and the beam width is large at a short distance, but the ultrasonic beam does not spread so much at a long distance. On the other hand, when the size of the transducer is small, the directivity becomes dull, and the beam width is small at a short distance, but the beam divergence becomes large at a long distance, and the echo height significantly decreases with distance.

  FIG. 6 shows the relationship between the beam size of the ultrasonic displacement sensor, the oscillation frequency, and the distance. The chain line is 40 kHz, the broken line is 100 kHz, and the solid line is 300 kHz. On the other hand, FIG. 7 shows the relationship between the energy density of the ultrasonic displacement sensor, the oscillation frequency and the distance. The energy density related to the output intensity is attenuated as the oscillation frequency becomes higher as shown in the figure. Similar to FIG. 6, the alternate long and short dash line is 40 kHz, the broken line is 100 kHz, and the solid line is 300 kHz.

  FIG. 8 shows the measured values of the beam size when the oscillation frequencies are 40 kHz and 300 kHz. If the beam size is 300 kHz, a working distance of 200 mm from the work 6 (cylinder block) to the master sensor 1 corresponds to an appropriate measurement area of 20 mm. Can be The oscillation frequency can be 200 to 400 kHz, the working distance can be 150 to 250 mm, and the beam size can be 15 to 25 mm, which is a practical value for the cylinder block. Further, by setting the distance from the master sensor 1 and the slave sensor 2 to the reference surface 7 to 150 to 200 mm, it is not necessary to bring the sensors close to each other in the cylinder block manufacturing line, so that the position control for stopping the work 6 is easy. Therefore, the sensor position does not become an obstacle for processing the work 6.

  If the oscillation frequency is 200 to 400 kHz and the operating distance is 150 to 250 mm, the resolution can be improved to about 0.1 mm. By setting the oscillation frequency of ultrasonic waves to 200 to 400 kHz, the beam size of ultrasonic waves can be reduced and the area of the measurement surface can be reduced. Further, by setting the beam size of the transmitted ultrasonic wave at the identification portion to be 15 to 20 mm, the production of the measurement surface does not hinder the production of a complicated shape such as a cylinder block by casting. However, when an electric signal close to the resonance frequency thereof is applied to the ultrasonic elements 31 and 32 in a pulsed manner, a phenomenon in which ultrasonic vibration mechanically lasts for a short time occurs even after the electric signal disappears, and the element is a reflection type. Therefore, if this phenomenon continues for a long time, detection becomes difficult.

  FIG. 9 shows a time change of the output voltage from oscillation to reception when the oscillation frequency is set to about 40 kHz as in the conventional case. The ultrasonic wave is transmitted and then the reflected wave is received, but the attenuation is small, so that multiple reflection occurs. There was a risk that the received wave would be detected incorrectly. On the other hand, when the oscillation frequency is set to 200 to 400 kHz, the attenuation is large as shown in FIG. 10 and the influence of multiple reflection can be reduced, and the variation in measurement can be reduced.

  FIG. 11 shows the discrimination effect with respect to the temperature when the master sensor 1 and the slave sensor 2 are used as one set. When the temperature rises by 10 ° C., the sound velocity rises, so the measured value at 200 mm is 196.5 mm, but since the difference is calculated, this effect can be ignored. Actually, the change in the temperature rise of 10 ° C. in the step of 1 mm is about 0.017 mm.

  FIG. 12 shows the timing of oscillating ultrasonic waves when the master sensor 1 and the slave sensor 2 are used as one set. The oscillation of the slave sensor 2 is delayed with respect to the oscillation of the master sensor 1 by a time sufficient to prevent the two ultrasonic waves from interfering with each other, which is longer than the time required to reciprocate over an operating distance of 200 mm and is not transmitted at the same time. Further, the CPUs 33 and 34 are synchronized with a common clock so that the two timings do not shift with the passage of time.

  Further, in order to reduce the variation of the measured value, it is desirable to repeat the measurement number of times 32 to 64 times with one identification. Further, it is desirable to calculate the median value of the repeated measurement values like a median filter and to make it stand out by excluding different values that stand out.

  FIG. 13 shows a case where the hole 9 is machined with an inclination or an eccentricity with respect to the reference plane 7. The measured value by the slave sensor 2 is slightly longer in the arrow of FIG. 13 than in the case of being processed correctly as shown in FIG. Therefore, the quality of processing may be directly determined by the value measured as the depth of the hole 9. However, since the beam size of the transmitted ultrasonic wave is set to 15 to 25 mm, it is affected by the inclined surface of the hole 9. Therefore, as described with reference to FIGS. 4 and 5, a work number is given to each model, a master work 11 having a hole of a predetermined shape is measured as a reference of the work 6 for each model, and registered in the discrimination data table 12. It is desirable to judge the quality by comparing the value with the actually measured value.

  Further, the master work 11, inclined holes, eccentric holes, bent like prepared model to which processing error hole, if learning seeking happens in advance what measurements and quality decision It can be performed in more detail and its aspect can be determined.

  FIG. 14 shows a state in which the residue 10 remains in the processed hole, and examples of the residue 10 include chips, drill defects, and unprocessed portions. The measured value by the slave sensor 2 is shorter in the arrow in FIG. 14 than in the case where the slave sensor 2 is correctly processed as shown in FIG. Therefore, the quality of processing may be directly determined by the value measured as the depth of the hole 9. However, it is affected by various factors such as the size and shape of the residue 10 and the beam size of the transmitted ultrasonic waves of 15 to 25 mm. Therefore, as described with reference to FIGS. 4 and 5, a work number is given to each model, and a crack, a cavity, or a surface roughness within an allowable range, which is a normal surface condition, is used as a reference of the work 6 for each model. It is desirable to measure the masterwork 11 that it has, register it in the discrimination data table 12, and compare the value with the actually measured value to determine whether it is good or bad.

  Further, actually the residue taken up 10 to the master work 11, if learning seeking happens in advance what measurements performed quality decision in more detail, to distinguish the appearance or cause it can.

  As described above, in the description from FIG. 3 onward, the case where the hole depth is obtained from the reference position has been described as an example. However, in a casting such as a cylinder block, defects such as surface flaws and casting cavities are generated regardless of before and after processing. It can be similarly determined. In that case, the reference surface 7 and the measurement surface 8 may be measured as the same surface by the master sensor 1 and the slave sensor 2 and compared with a normal surface registered in advance.

1 Master Sensor 2 Slave Sensor 3 Sensor Unit 4 Machine Tool Controller 5 Machine Tool 6 Work 7 Reference Surface 8 Measuring Surface 9 Hole 10 Residue 11 Master Work 12 Discrimination Data Table 31, 32 Ultrasonic Element 33, 34 CPU
35, 36 memory

Claims (9)

In an in-line inspection device that non-destructively inspects workpieces on the processing line,
A master sensor that transmits an ultrasonic wave toward a reference surface or a measurement surface provided at a predetermined position of the work and receives a reflected wave, and measures the time from transmission to reception.
When the master sensor transmits an ultrasonic wave toward the reference surface, the ultrasonic wave is transmitted toward the measurement surface to receive a reflected wave, and the time from transmission to reception is measured, and the master sensor is When transmitting ultrasonic waves toward the measurement surface, the ultrasonic wave is transmitted toward the reference surface to receive the reflected wave, and a slave sensor that measures the time from transmission to reception,
A master data having a reference surface and a measurement surface serving as a reference, and a discrimination data table in which a difference value obtained by measuring the reference surface and the measurement surface by the master sensor and the slave sensor is registered; An in-line inspection apparatus, which determines the quality of processing by comparing the difference value obtained by measuring the reference surface and the measurement surface by the master sensor and the slave sensor with the value in the determination data table. In an in-line inspection device that non-destructively inspects workpieces on the processing line,
A master transmission unit that transmits ultrasonic waves toward a reference surface or a measurement surface provided at a predetermined position of the work, a master reception unit that receives the reflected wave, and a master time measurement that measures the time from transmission to reception A master sensor having a section,
A slave transmission unit that transmits an ultrasonic wave toward the measurement surface or the reference surface, a slave reception unit that receives the reflected wave, and a slave time measurement unit that measures the time from transmission to reception, When the master sensor transmits ultrasonic waves toward the reference surface, the ultrasonic waves are transmitted to the measurement surface, and when the master sensor transmits ultrasonic waves toward the measurement surface, toward the reference surface A slave sensor that transmits ultrasonic waves,
A master data having a reference surface and a measurement surface, which serves as a reference, and a discrimination data table in which a difference value obtained by measuring the reference surface and the measurement surface by the slave sensor is registered; An in-line inspection apparatus characterized by judging the quality of processing by comparing the difference value obtained by measuring the reference surface and the measurement surface by the master sensor and the slave sensor with the value of the judgment data table.   The in-line inspection device according to claim 1 or 2, wherein the ultrasonic waves are transmitted alternately between the master sensor and the slave sensor.   The in-line inspection apparatus according to any one of claims 1 to 3, wherein a clock signal that is a reference time for transmitting an ultrasonic wave is generated by the master sensor, and the ultrasonic wave is generated by the slave sensor in synchronization with the clock signal. In-line inspection device, which is characterized by transmitting.   The in-line inspection device according to any one of claims 1 to 4, wherein the master work is provided with a hole having a predetermined shape as the measurement surface.   The in-line inspection device according to any one of claims 1 to 4, wherein the master work has a normal surface state as the measurement surface. An in-line inspection method that non-destructively inspects workpieces on the processing line,
The master sensor is directed to a reference surface provided at a predetermined position of the work , the slave sensor transmits ultrasonic waves toward the measurement surface provided on the work, and receives a reflected wave, or the master sensor is towards the measuring surface, the slave sensor receives the reflected wave by transmitting ultrasonic waves toward the reference plane, the reference plane by the master sensor and the slave sensor measures each time from transmission to reception and Find the first difference value of the measured surface,
A master work having a reference surface and a measurement surface as a reference, the reference surface and the measurement surface are measured by the master sensor and the slave sensor using the master work, and using a discrimination data table in which a difference value is registered. An in-line inspection method is characterized in that the quality of the processing is determined by comparing the difference value of the determination data table with the first difference value.   The in-line inspection method according to claim 7, wherein the ultrasonic waves are transmitted alternately between the master sensor and the slave sensor.   9. The in-line inspection method according to claim 7, wherein the master sensor generates a clock signal that is a reference time for transmitting the ultrasonic wave, and the slave sensor transmits the ultrasonic wave in synchronization with the clock signal. Characteristic in-line inspection method.