JP5817990B2 - Tire inspection device - Google Patents

Description

  The present invention relates to a tire inspection apparatus that inspects a tire in a nondestructive manner. In particular, the present invention relates to a CT apparatus that takes a cross-sectional image of a tire.

  In recent years, as a device for inspecting the inside of a tire in a nondestructive manner, a CT (Computed Tomography) device for obtaining a cross-sectional image of a tire has been used.

  FIG. 10 is a conceptual diagram (front view) of a conventional tire CT apparatus. This is a tire CT apparatus described in Patent Document 1. The tire 101 is attached to a general commercially available wheel 102, and the wheel 102 is attached to a holder 103 so that the rotation axis HA of the wheel is in a specified position. A load mechanism 104 is fixed to the holder 103, and the load mechanism 104 is added to the wheel 103. In this configuration, the pressure plate 105 is pressed against the ground contact surface (outer peripheral surface) of the tire 101 to apply a load.

  The holder 103 is supported by a support base 106 so as to be rotatable with respect to the rotation axis HA of the wheel, and the tilted drive unit 107 expands and contracts, so that the loaded tire is centered on the rotation axis HA of the wheel together with the holder 103. Tilted and positioned.

  The CT unit 108 includes an X-ray source 108a, an X-ray detector 108b, a CT mechanism unit 108c, and a control processing unit (not shown). The CT unit 108 captures a cross-sectional image of a horizontal imaging surface TP that passes through the rotation axis HA of the wheel. The X-ray source 108a emits a fan-shaped X-ray 108d along the imaging surface TP, and the X-ray detector 108b decomposes and measures the X-ray 108d transmitted through the subject along the fan. The measurement is performed as a so-called TR type CT apparatus. That is, the tire 101 is measured along the fan in the horizontal direction (direction perpendicular to the paper surface of the drawing) together with the fan 106 and the tilt drive unit 107 while the X-ray completely traverses the subject (Translate). Then, the tire 101 is rotated stepwise (Rotate) by the fan angle of the X-ray 108d with respect to the CT rotation axis RA perpendicular to the imaging surface TP together with the support base 106 and the tilt driving unit 107. When measurement data from 180 ° direction is obtained by repeating the measurement while moving laterally and step rotation, the tire 101 and the wheel 102 (and the pressure plate 105, the holder 103, and a part of the support base 106) are obtained from this data. A cross-sectional image at the photographing plane TP position is reconstructed.

  Furthermore, a plurality of mutually inclined sectional images passing through the rotation axis HA of the wheel can be obtained by photographing the sectional image by changing the inclination position of the holder 103 by the inclination driving unit 107. FIG. 11 is a diagram showing a position 109 of a cross-sectional image taken with respect to the tire 101 and the pressure plate 105 in the conventional example.

  In the conventional example, it is possible to obtain a plurality of mutually inclined cross-sectional images passing through the rotation axis HA of the wheel with respect to a loaded tire, and deformation on a surface inclined at an arbitrary angle from a surface orthogonal to the pressure plate 105. Can be obtained for each angle.

  This cross-sectional image for each inclination angle shows the deformation of the tire shape over time when the tire rotates, and the deformation and movement amount of the members inside the tire, so that the durability, cushioning, vibration, noise of the tire It is important to analyze the etc.

JP-A-6-218844

  However, in the conventional example, the tire 101, the wheel 102, the holder 103, the load mechanism 104, and the pressure plate 105 are all inclined with respect to the fixed imaging surface TP to change the cross-sectional position. ing. Here, the holder 103, the load mechanism 104, and the pressure plate 105 are required to have high rigidity so that the load state does not change even when inclined, and are large and heavy. For this purpose, a large-scale tilt driving unit 107 and a support base 106 for tilting them are necessary, and the mechanism for parallel movement and step rotation of the CT mechanism unit 108c becomes large, which makes it difficult to ensure accuracy and manufacture. Is an issue.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tire inspection apparatus that inspects a loaded tire without using a large-scale mechanism.

In order to achieve the above-mentioned object, the invention according to claim 1 is directed to a load means for applying a load by pressing a pressure plate against a ground contact surface with respect to a tire mounted and held on a wheel and pressurized with air therein, and the load. Corresponding to at least two planes parallel to the end surface of the wheel in the rotational axis direction from CT means for photographing a plurality of parallel sectional images by photographing a tire that is hung, and the plurality of parallel sectional images Each of the cross-sectional images of the wheel is obtained, the center coordinates of the wheel are obtained on the obtained cross-sectional image of the wheel, the position of the rotation axis of the wheel is obtained as a line connecting the obtained center coordinates of the wheel, The gist of the invention is to have an image processing unit that converts a cross-section from a parallel cross-sectional image to produce a plurality of cross-sectional images that are inclined with respect to each other and pass through the rotation axis of the wheel .

  With this configuration, a plurality of mutually parallel cross-sectional images are taken, and a plurality of mutually inclined cross-sectional images passing through the rotation axis of the wheel are obtained by cross-sectional conversion. Therefore, all the tires, wheels, and load means are loaded. In this state, it is possible to eliminate a large-scale tilt drive unit that tilts with respect to the rotation axis of the wheel.

The obtained plurality of inclined sectional images correspond to time-series plural sectional images when the tire rotates with respect to one section fixed to the tire, and are useful for analyzing the tire. In addition, a plurality of parallel sectional images themselves each other, since the cross-section converting seeking rotation axis of the wheel, precisely it is not necessary to adjust the positional relationship between the wheel and the CT unit, can be accurately planar reconstruction, the rotation of the wheel The position of the axis can be accurately determined three-dimensionally.

In order to achieve the above-mentioned object, the invention according to claim 2 photographed a tire loaded and held on a wheel so that the air inside is pressurized and a load is applied by pressing a pressure plate against a ground contact surface by a load means. A plurality of parallel cross-sectional images are input, and from each of the plurality of parallel cross-sectional images, wheel cross-sectional images corresponding to at least two planes parallel to the end surface in the rotation axis direction of the wheel are obtained, respectively. The center coordinates of the wheel are respectively obtained on the cross-sectional image of the wheel, the position of the rotation axis of the wheel is obtained as a line connecting the obtained center coordinates of the wheel, the cross-section is converted from the plurality of parallel cross-sectional images, and The gist of the invention is to have an image processing unit that creates a plurality of mutually inclined cross-sectional images passing through the rotation axis of the wheel .

  With this configuration, the same operation and effect as the first aspect of the invention can be obtained.

In order to achieve the above object, according to a third aspect of the present invention, in the tire inspection apparatus according to the first or second aspect, the image processing unit includes a plurality of inclined sectional images passing through the rotation axis of the wheel. One of the two tire cross-sectional images sandwiching the rotation axis of the wheel, one of which is folded back on the rotation axis of the wheel and displayed on top of each other, or one of the two tires is folded back on the rotation axis of the wheel and superimposed on each other The gist is to obtain the amount of deviation of the overlap between the two.

  With this configuration, two tire cross-sectional images sandwiching the rotation axis of the wheel are displayed with one of them folded back on the rotation axis of the wheel so as to overlap each other, so that the tire close to the pressure plate with reference to the tire cross-sectional image far from the pressure plate The deformation of the cross-sectional image can be easily visually confirmed.

  Alternatively, since the two tire cross-sectional images sandwiching the wheel rotation axis are folded back on one side of the wheel rotation axis and overlapped with each other, the amount of misalignment between the two tires is obtained. The deformation of the tire cross-sectional image close to the pressure plate can be obtained quantitatively.

In order to achieve the above object, according to a fourth aspect of the present invention, in the tire inspection apparatus according to the first or second aspect, the image processing section includes a plurality of mutually inclined cross-sectional images passing through the rotation axis of the wheel. In one of the above, when two tire cross-sectional images sandwiching the rotation axis of the wheel are displayed shifted from each other and overlapped with a predetermined portion, or are overlapped and displayed with a predetermined portion shifted from each other The gist is to determine the amount of misalignment between each other.

  With this configuration, the deformation of the tire cross-sectional image close to the pressure plate relative to the tire cross-sectional image far from the pressure plate can be visually recognized using a predetermined portion as a reference (fixed point).

  Alternatively, the deformation of the tire cross-sectional image close to the pressure plate relative to the tire cross-sectional image far from the pressure plate can be quantitatively obtained with a predetermined portion as a reference (fixed point).

In order to achieve the above object, according to a fifth aspect of the present invention, in the tire inspection apparatus according to the first or second aspect, the image processing unit includes a plurality of mutually inclined cross-sectional images passing through the rotation axis of the wheel. The gist is to determine the deformation of the wheel with respect to the rotation axis of the ring formed by a predetermined portion of the tire.

  With this configuration, using a plurality of cross-sectional images passing through the rotation axis of the wheel, the ring formed by the predetermined portion of the tire when the position of the predetermined portion of the tire is plotted on a plane orthogonal to the rotation axis of the wheel, The deformation of the wheel with respect to the rotation axis can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the tire inspection apparatus which test | inspects the loaded tire can be provided, without using a large-scale mechanism part.

The schematic diagram (front view) which showed the structure of the tire inspection apparatus which concerns on 1st embodiment of this invention. The figure which shows the position of the cross-sectional image image | photographed with respect to the tire and pressurization board in 1st embodiment. An example of the cross-sectional image image | photographed with respect to the tire and pressurization board in 1st embodiment. The flowchart of the cross-section conversion process which the image process part which concerns on 1st embodiment performs. Sectional drawing which shows the position of the wheel end surface which concerns on 1st embodiment, and two surfaces parallel to it. The geometric diagram which shows the setting of the inclined surface which concerns on 1st embodiment. An example of the cross-sectional image in the inclined surface which concerns on 1st embodiment. The graph which shows the deformation | transformation of the annular ring which a bead forms in 1st embodiment. The figure which shows the deformation | transformation state of the annular ring which a bead forms in 1st embodiment. The conceptual diagram (front view) of the conventional CT apparatus for tires. The figure which shows the position of the cross-sectional image image | photographed with respect to the tire and pressure plate in a prior art example.

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

(Configuration of the first embodiment of the present invention)
The configuration of the first embodiment of the present invention will be described below with reference to FIG.

  FIG. 1 is a schematic diagram (front view) showing a configuration of a tire inspection apparatus according to a first embodiment of the present invention.

  The tire inspection apparatus 1 includes a load mechanism unit 4 that applies a load to the tire 2, a CT unit (CT unit) 5 that captures a cross-sectional image, and an image processing unit 6 that performs image processing on the cross-sectional image and evaluates the tire.

  The load mechanism unit 4 includes a holder 4a, a load mechanism (load means) 4b, and a pressure plate 4c. The tire 2 is mounted and held on a general commercially available wheel 3 so that the internal air is pressurized, and the wheel 3 has a rotational axis HA (hereinafter abbreviated as “axis HA”) at a specified position. The load mechanism 4b is fixed to the holder 4a. The load mechanism 4b presses the pressure plate 4c against the ground contact surface (outer peripheral surface) of the tire 2 to apply a load. The load mechanism 4b is controlled by a load control unit (not shown).

  The CT unit 5 includes an X-ray source 5a, an X-ray detector 5b, a rotation / translation mechanism 5c, elevating mechanisms 5d and 5e, and a control processing unit 5g. The CT unit 5 captures a cross-sectional image of the horizontal imaging surface TP. The X-ray source 5a emits fan-shaped X-rays 5f along the imaging plane TP, and the X-ray detector 5b measures the X-rays 5f that have passed through the subject by decomposing along the fan and outputs them as transmission data. To do.

  The rotation / translation mechanism 5c moves the tire 2 together with the holder 4a in a horizontal direction (a direction perpendicular to the drawing in the drawing) so as to cross the X-ray 5f along the imaging surface TP (without changing the posture). ) Further, the rotation / translation mechanism 5c rotates the tire 2 together with the holder 4a with respect to the CT rotation axis RA perpendicular to the imaging surface TP and passing through the substantially center of the tire 2.

  The elevating mechanisms 5d and 5e move the X-ray source 5a and the X-ray detector 5b up and down by the same amount (up and down along the plane of the paper) to position the imaging plane TP (and the X-ray 5f). Let

  The control processing unit 5g is a normal computer and includes a CPU, a storage unit, an interface, a display unit, an input unit, a mechanism control unit, a communication unit, and the like. The control processing unit 5g controls the X-ray source 5a, the X-ray detector 5b, the rotation / translation mechanism 5c, and the elevating mechanisms 5d and 5e as functions performed by the CPU based on the program. ) And a function of reconstructing cross-sectional images of the tire 2 and the wheel 3 from transmission data obtained by scanning.

  The image processing unit 6 is a normal computer and includes a CPU, a storage unit, an interface, a display unit, an input unit, a communication unit, and the like. The image processing unit 6 has a function of converting a plurality of cross-sectional images taken from the control processing unit 5g, a function of evaluating the tire 2, and the like as functions performed by the CPU based on a program.

(Operation of the first embodiment)
The operation of the first embodiment will be described with reference to FIGS.

  Referring to FIG. 1, first, the load mechanism unit 4 is in a state where a predetermined load is applied to the tire 2. The elevating mechanisms 5d and 5e raise and lower the X-ray source 5a and the X-ray detector 5b to set the imaging surface TP. In this state, the CT unit 5 performs scanning (cross-sectional image capturing scanning) to capture a cross-sectional image of the tire 2.

  Scanning is performed as a so-called TR type CT apparatus. That is, the X-rays transmitted through the holder 4a (and the CT rotation axis RA) and the tire 2 along the imaging surface TP while translating the X-ray 5f completely across the tire 2 (Translate) are measured, Next, the tire 2 together with the holder 4a is rotated stepwise (Rotate) by the fan angle of the X-ray 5f with respect to the CT rotation axis RA. Measurement data from the 180 ° direction is obtained by repeating this lateral movement measurement and step rotation. The above measurement is controlled by the control processing unit 5g, and the transmission data output from the X-ray detector is taken into the control processing unit 5g. The control processing unit 5g reconstructs a cross-sectional image of the photographing surface TP position of the tire 2 and the wheel 3 (and the pressure plate 4c and a part of the holder 4a) from the acquired transmission data. Reconfiguration is performed by a known process.

  Subsequent to the first scan, in the state where the tire 2 is kept at the same load, the elevating mechanisms 5d and 5e change and set the imaging surface TP, and perform the second scan and reconstruction in the same manner.

  Further, in a state in which the tire 2 is kept at the same load, the control processing unit 5g similarly controls scanning and reconfiguration while changing the imaging surface TP at a predetermined interval, and a plurality of tires 2 in the loaded state are mutually connected. Parallel cross-sectional images are obtained, stored, and transmitted to the image processing unit 6.

  FIG. 2 is a diagram showing the position of the cross-sectional image 7 taken with respect to the tire 2 and the pressure plate 4c in the first embodiment. The plurality of cross-sectional images 7 are parallel to the xy plane and arranged at predetermined intervals in the z direction, and form three-dimensional data in which voxels of a predetermined size are stacked. The voxel position can be expressed by coordinates xyz. Although the rotation axis HA of the wheel 3 is substantially parallel to the y-axis, it is not exactly parallel due to an error, and the position on the cross-sectional image 7 is not accurately determined.

  FIG. 3 is an example of a cross-sectional image 7 taken with respect to the tire 2 and the pressure plate 4c in the first embodiment. 3 (a), 3 (b), and 3 (c) are cross-sectional images 7a, 7b, and 7c showing the positions in FIG. 2, respectively. It is a cross-sectional image passing through the side. In addition, although the holder 4a also appears in the cross-sectional images 7a, 7b, and 7c, illustration is omitted.

  The image processing unit 6 performs cross-sectional conversion processing on the plurality of parallel cross-sectional images 7 of the received tire 2 and evaluates the tire 2.

  The cross section conversion process will be described with reference to FIG. FIG. 4 is a flowchart of the cross-section conversion process performed by the image processing unit 6.

  In step S1, the wheel end face in the axis HA direction is obtained as follows. First, two end points P1 and P2 of the wheel 3 are obtained using the cross-sectional image 7a (FIG. 3A). To do this, the wheel 3 is extracted by binarization processing, an image is created where the wheel 3 is “1” and the others are “0”, and the rightmost “1” in the upper half of the screen is determined as P1, and the screen By obtaining “1” at the rightmost end in the lower half and setting it to P2, the positions of the points P1, P2 can be obtained in the x, y, z coordinates.

  Next, similarly, two end points P3 and P4 of the wheel 3 are obtained using the cross-sectional image 7c (FIG. 3C).

Since the wheel end surface is determined when three points on the surface are known, for example, the end surface is obtained from the points P1, P2, and P3. Specifically, the equation representing the wheel end face is
y = a.x + b.z + c (1)
, The coordinate values (x1, y1, z1), (x2, y2, z2) and (x3, y3, z3) of the three points P1, P2, and P3 are respectively expressed as x, y, and z in Equation (1). By solving simultaneous equations for a, b, and c that can be substituted, a, b, and c are obtained, and the wheel end face is obtained.

  Further, referring to FIG. 5, two planes parallel to the wheel end face are obtained.

FIG. 5 is a cross-sectional view showing the position of the wheel end surface and two surfaces parallel to the wheel end surface, and is represented by a line of intersection with the cross-sectional image 7b. The planes 9a and 9b parallel to the wheel end surface are surfaces obtained by moving the wheel end surface 8 by d1 and d2 in the y direction, respectively, and are surfaces close to both ends of the wheel 3 and pass through the rim portion (portion contacting the tire). Surface. Here, d1 and d2 are constants determined in advance for each wheel type. Using known coefficients a, b, c, the plane 9a is an equation:
y = a · x + b · z + c−d1 (2)
And the plane 9b is an equation,
y = a · x + b · = z + c−d2 (3)
Set by.

  In step S2, a first cross-sectional image on a plane 9a parallel to the end face is created by cross-sectional transformation. This is because if the points are set in a grid pattern on the plane 9a known from the equation (2), the x, y, z coordinates of each point can be calculated, so that the cross section can be converted from the cross section image 7. .

  In step S3, the center point A of the arc formed by the outer periphery of the wheel 3 is obtained on the first cross-sectional image created in step S2. For this, for example, fitting between the outer circumference and a circle is used. The center point A is obtained by x, y, z coordinates, and a coordinate value (xa, ya, za) (center coordinates) is obtained.

  In step S4, similarly to step S2, a second cross-sectional image on the plane 9b parallel to the end face is created by cross-sectional transformation.

  In step S5, as in step S3, the center point B of the arc formed by the outer periphery of the wheel 3 is obtained by the x, y, z coordinates on the second cross-sectional image created in step S4, and the coordinate values (xb, yb , Zb) (center coordinates).

  In step S6, the position of the rotation axis HA of the wheel 3 is obtained. That is, the axis HA is determined as a line connecting the center point A and the center point B. The axis HA is described by, for example, the coordinates of one point B on the axis HA and the unit vector η in the direction of the axis HA.

  In step S7, an inclined surface passing through the axis HA is set as follows.

  FIG. 6 is a geometric view showing the setting of the inclined surface. The axis HA is defined by the point B and the unit vector η and is known. Let x, y, and z components of η be ηx, ηy, and ηz.

First, a unit vector ξ (its x, y, z component) orthogonal to η and parallel to the xy plane is expressed by the following equation:
ξx = ηy / √ (ηx ^ 2 + ηy ^ 2),
ξy = −ηx / √ (ηx ^ 2 + ηy ^ 2),
ξz = 0 (4)
Ask for. The surface defined by the points B, η, and ξ is the surface that is closest to the horizontal through the axis HA and is the reference surface 10 that is orthogonal to the load plate 4c.

Then the vector product,
ζ = ξ × η (5)
Thus, the normal vector ζ of the reference plane 10 is obtained. Next, a unit vector ξi obtained by rotating ξ by θi with respect to the axis HA is expressed by the following equation:
ξi = ξ · cos (θi) + ζ · sin (θi) (6)
An inclined plane 10-i inclined by θi from the reference plane 10 is set by a point B in the plane and two orthogonal unit vectors η and ξi along the plane.

  Note that by setting the number I and the inclination angle θi in advance, a plurality of inclined surfaces 10-i (i = 1, 2,... I) are automatically set. Further, the inclined surface 10-i generally includes a non-inclined surface (θi = 0).

  In step S8, a cross-sectional image 11-i on the inclined surface 10-i is created by cross-sectional transformation for all of the inclined surfaces 10-i (i = 1, 2,... I). This is because if the unit vector, η and ξi are used to set points (n · ξi + m · η) on the inclined surface 10-i in a lattice shape, the x, y, and z coordinates of each point can be calculated. The cross section can be converted from the image 7.

  The cross-section conversion process ends in steps S1 to S8.

  The image processing unit 6 evaluates the tire 2 as follows using the cross-sectional image of the inclined surface 10-i subjected to the cross-section conversion processing.

  FIG. 7 is an example of a cross-sectional image on an inclined surface. This shows a cross-sectional image 11-i on the inclined surface 10-i. All cross-sectional images 11-i (i = 1, 2,... I) are cross-sections passing through the rotation axis HA of the wheel 3, and are different from each other in the position of the pressure plate 4c and the deformation of the tire.

  The image processing unit 6 displays two tire cross-sectional images 2a and 2b sandwiching the wheel rotation axis HA in one cross-sectional image 11-i so that one of them is folded by the wheel rotation axis HA and overlapped with each other. This superimposed display may be an added image, a difference image, or an image with enhanced differences. Thereby, the deformation | transformation of the tire cross-sectional image 2a far from the pressurization board 4c and the deformation | transformation of the tire cross-sectional image 2b near can be visually compared. Further, the image processing unit 6 quantitatively calculates and displays the distribution of the amount of deviation of the overlap between the distant tire cross-sectional image 2a and the tire cross-sectional image 2b when they are folded and overlapped with each other. The amount of deviation is, for example, by overlapping an arrow having a length corresponding to the amount of deviation on a tire edge on a cross-sectional image that is overlapped or not superimposed, or by adding a color that corresponds to the amount of deviation. Can be displayed. It can also be displayed as a 3D display graph or the like in which a bar having a height corresponding to the amount of deviation is set on the tire edge on the cross-sectional image.

  Since there is little deformation on the side far from the pressure plate 4c, the superimposed display and the display of the displacement amount described above generally represent the deformation of the tire near the pressure plate 4c.

  Furthermore, this process can be performed for each cross-sectional image 11-i to compare the deformation for each inclination angle θi.

  Next, as a second evaluation, the image processing unit 6 obtains deformation with respect to the axis HA (deformation from a circle centered on the axis HA) with respect to the ring formed by a predetermined part of the tire 2. The predetermined part includes a bead 12 (reinforcing wire), an outer peripheral side of the inner wall 13, or a grounding surface of the tread 14 (grounding part). When there is no deformation, these circular rings are cylinders or circles centered on the axis HA.

  Specifically, the bead 12 on one side (right side) is considered here. In each cross-sectional image 11-i, four cross-sections of the bead 12 are extracted by binarization processing, and each position, more precisely, the center of gravity or the center position is obtained. Next, the distance (local radius) Ra between the position of the bead 12a (right side) far from the pressure plate 4c and the axis HA and the distance Rb between the position of the bead 12b (right side) close to the pressure plate 4c and the axis HA are obtained. Furthermore, as shown in FIG. 8, the relationship between the inclination angle θi and the distance R is displayed as a graph. The distances Ra and Rb indicate deformation of the ring formed by the bead 12 with respect to the axis HA (deformation from a circle having a radius R0 centered on the axis HA).

  Moreover, as shown in FIG. 9, the deformation state of the ring of the bead 12 on the plane orthogonal to the axis HA is displayed. This can be drawn by plotting the position (θi, Ra, Rb) of the bead 12, and at the same time, a circle 15 (circle with a radius R0 at the center of the axis HA) is also drawn and compared for display. When the difference is small and difficult to see, enlargement display and difference highlight display are performed. Furthermore, as a deformation parameter, the circle of the plotted bead 12 is fitted with a circle to obtain the average center of the circle, and the deviation of the average center of the circle from the axis HA can be obtained.

  Here, the bead 12 on one side (right side) is considered, but the bead 12 on the other side (left side) can be evaluated in the same manner, and the average of left and right may be evaluated.

  Similarly, the deformation of the ring formed on the outer peripheral side of the inner wall 13 of the tire 2, the grounding surface of the tread 14 (grounding part), etc. on a plane orthogonal to the axis HA, and the deviation of the average center of the ring are similarly obtained. be able to. In this case, the deformation of the ring and the deviation of the average center of the ring can be obtained at a plurality of positions in the direction of the axis HA, and can be displayed graphically.

  Next, as a third evaluation, the stress of the tire is analyzed. Since a plurality of cross-sectional images 11-i passing through the axis HA are obtained for each inclination angle θi, the cross-sectional image 11-i is a multi-sectional image along the passage of time when the tire rotates with respect to one cross-section fixed to the tire. It can be considered that the deformation changes with time, and the stress distribution as a repeated change component of the stress (tensile, pressure, shearing force, etc.) of each section is known. As a result, a position where the stress distribution is strong (that is, a portion that is strongly bent and stretched) can be found, and a portion that is easily deteriorated when subjected to repeated stress can be found.

  This evaluation can be used for designing and manufacturing a tire having a uniform stress distribution and improved durability. When the stress distribution is simulated and estimated at the time of design, the validity of the simulation can be evaluated by comparing.

  The photographing and evaluation described above can be performed by comparing the tire load and the air pressure inside the tire, and comparing and evaluating them.

(Effects of the first embodiment)
According to the first embodiment, a plurality of cross-sectional images 7 that are parallel to each other are photographed, and a plurality of cross-sectional images that are inclined with respect to the rotation axis HA of the wheel are obtained by cross-sectional conversion. It is possible to eliminate a large-scale tilt drive unit that tilts all the mechanism units 4 with respect to the rotation axis HA of the wheel in a loaded state. Further, since the inclination is eliminated, the load mechanism portion 4 does not require high rigidity, and the rotation / translation mechanism 5c of the CT portion 5 does not become large, so that accuracy and manufacturing difficulty are remarkably improved.

  According to the first embodiment, the obtained plurality of cross-sectional images that are inclined to each other correspond to a time-series multi-sectional image when the tire rotates with respect to one cross-section fixed to the tire. It is useful in.

  According to the first embodiment, the rotation mechanism HA of the wheel is obtained from a plurality of cross-sectional images 7 themselves that are parallel to each other, and the cross-section is converted, so that the load mechanism unit 4 and the CT unit 5 (that is, the wheel 3 and the CT unit 5). It is not necessary to match the positional relationship between and accurately, and the cross-section can be accurately converted. Further, an attachment error of the wheel 3 to the load mechanism 4 or a shift of the axis HA when a load is applied is automatically corrected, and the cross section can be accurately converted.

  According to the first embodiment, using the cross-sectional image of the surface passing through the wheel rotation axis HA, two tire cross-sectional images 2a and 2b sandwiching the wheel rotation axis HA are used, one of which is the wheel rotation axis HA. Since they are folded and overlapped and displayed, the deformation of the tire cross-sectional image 2b close to the pressure plate 4c can be easily visually recognized with reference to the tire cross-sectional image 2a far from the pressure plate 4c.

  According to the first embodiment, using the cross-sectional image of the surface passing through the wheel rotation axis HA, two tire cross-sectional images 2a and 2b sandwiching the wheel rotation axis HA are used, one of which is the wheel rotation axis HA. Since the amount of deviation of the overlap when folded and overlapped with each other is obtained, the deformation of the tire cross-sectional image 2b close to the pressure plate 4c can be quantitatively obtained on the basis of the tire cross-sectional image 2a far from the pressure plate 4c.

  According to the first embodiment, the predetermined part of the tire 2 when the position of the predetermined part of the tire 2 is plotted on a plane orthogonal to the axis HA using the cross-sectional image of the surface passing through the rotation axis HA of the wheel. Can be determined for the axis HA (a circle centered on the axis). Further, the deviation from the axis HA can be obtained with respect to the average center of the ring formed by the predetermined part. As the predetermined portion, in particular, deformation of a bead, an inner wall or a ring formed by a tread of a tire can be obtained.

  Moreover, according to 1st embodiment, the difference of a deformation | transformation of the tire 2 by the difference in a load and air pressure can be compared by imaging | photography by changing the load and air pressure of the tire 2. FIG.

(Modification of the first embodiment)
In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. The following modifications can be implemented in combination.

(Modification 1)
In the first embodiment, the end face 8 of the wheel is obtained from the three end points P1, P2, P3 of the wheel 3, but may be obtained from four points, P1 to P4 on average. Alternatively, the end points may be obtained from three or more cross-sectional images in the cross-sectional image 7, and the wheel end face 8 may be obtained on the average from these end points.

(Modification 2)
In the first embodiment, the rotation axis HA of the wheel is obtained by obtaining the center point A and the center point B of the wheel 3 on the first sectional image and the second sectional image parallel to the end face 8 of the wheel, respectively. However, the center point of the wheel 3 can be obtained on three or more parallel cross-sectional images, and the wheel rotation axis HA can be obtained on average from the obtained three or more center points.

(Modification 3)
In the first embodiment, in the inclined cross-sectional image 11-i, the tire 2 is folded and displayed with the axis HA, but instead of being folded with the axis HA, one tire cross-sectional image sandwiching the axis HA is rotated by 180 °. Alternatively, after the mirror image is inverted, the image may be shifted and fitted to the other tire cross-sectional image so that the predetermined portion is best overlapped and displayed. The predetermined parts to be fitted include, for example, the bead 12, the rim portion of the wheel 3 (the portion in contact with the tire), the entire tire inner wall 13 or a designated portion of the inner wall 13, the ground contact surface of the tread 14, the entire tire 2 (average ), Etc.

  Thereby, the deformation | transformation of the tire cross-sectional image 2b close | similar to the pressurization board 4c with respect to the tire cross-sectional image 2a far from the pressurization board 4c can be easily visually recognized on the basis of a predetermined | prescribed site | part (fixed point).

  In addition, after rotating one of the tire cross-sectional images sandwiching the axis HA by 180 ° or reversing the mirror image and shifting the two tire cross-sectional images, the other tire cross-sectional images are fitted and overlapped so that the overlapping of the predetermined part is the best. The amount of deviation of the overlap is obtained and displayed in the same manner as in the first embodiment.

  Thereby, the deformation | transformation of the tire cross-sectional image 2b close | similar to the pressurization board 4c with respect to the tire cross-sectional image 2a far from the pressurization board 4c can be calculated | required quantitatively on the basis of a predetermined | prescribed site | part (fixed point).

(Modification 4)
In the first embodiment, in the inclined cross-sectional image 11-i, the tire 2 is folded back with the axis HA, and the amount of deviation of the overlap when it is displayed or overlapped is obtained, but the inclined cross-sectional image 11- when the load is applied. You may make it obtain | require the shift | offset | difference amount of an overlap when it displays so that the axis | shaft HA may correspond, and the axis | shaft HA matches the inclination cross-sectional image 11-i when i and no load are applied.

  Even if the axis HA is displaced due to the load, the displacement is corrected and accurately overlapped. Therefore, the deformation of the tire cross-sectional image can be easily visually confirmed or the deformation can be obtained quantitatively based on the tire cross-sectional image when no load is applied. Can do.

(Modification 5)
In the modified example 3, in the inclined cross-sectional image 11-i, one tire cross-sectional image sandwiching the axis HA is fitted to the other tire cross-sectional image so that the overlap of a predetermined part is the best, The amount of deviation of the overlap when overlapped is obtained. The sloped cross-sectional image 11-i when the load is applied and the sloped cross-sectional image 11-i when the load is not applied are such that the overlap between the predetermined portions is the best. Fitting may be performed so as to obtain the amount of deviation of the overlap when displayed or superimposed.

  Even if the axis HA is displaced due to the load, the displacement is corrected and accurately superimposed, so that the deformation of the tire cross-sectional image with respect to the tire cross-sectional image when no load is applied can be easily viewed using the predetermined part as a reference (fixed point) Alternatively, the deformation can be obtained quantitatively.

(Modification 6)
In the first embodiment, as a second evaluation, the image processing unit 6 seeks deformation with respect to the axis HA with respect to the ring formed by a predetermined part of the tire 2, but here, the inner wall 13 of the tire 2 is further calculated. The entire deformation of the ring formed by the outer wall of the tire 2 (including the contact surface of the tread 14), etc., with respect to the axis HA can be obtained and displayed three-dimensionally.

For example, three-dimensional display can be performed using the point B as the origin and coordinates (ξ, η, ζ) (see FIG. 6) in an orthogonal coordinate system defined by the unit vectors ξ, η, ζ.
Specifically, the point cloud is obtained by obtaining the distance R from the axis HA at each position (η) in the axis HA direction of each part (inner wall, outer wall, etc.) on the tilted sectional image 11-i at each tilt angle θi. (Θi, η, R) is obtained and used as 3D point cloud data converted into orthogonal coordinates (ξ, η, ζ). Three-dimensional display of each part (inner wall, outer wall) is performed using this 3D point cloud data or STL (Standard Triangulated Language) data created by converting the 3D point cloud data.

  Further, using the 3D point cloud data or STL data of each part (inner wall, outer wall, etc.) created, error verification for the 3D-CAD data (design data) of the tire can be performed. The error verification is performed by obtaining a difference when fitting a predetermined portion between the created data and CAD data and overlaying them to display in 3D. Examples of the predetermined places to be fitted include, for example, the rotation axis HA of the wheel, the bead 12, the rim portion of the wheel 3 (the portion in contact with the tire), the entire tire inner wall 13 or a designated portion of the inner wall 13, the ground contact surface of the tread 14, and the tire 2 whole (on average, make the whole fit), etc.

  The error verification described above is performed between 3D point cloud data or STL data created by photographing a cross section of another tire of the same type whose performance has been confirmed by another mechanical evaluation test, instead of 3D-CAD data. Can also be done.

(Modification 7)
In the modified example 6, a point group (θi, η, R) created by each part (inner wall, outer wall, etc.) is obtained from each inclined cross-sectional image 11-i, and this is converted into orthogonal coordinates (ξ, η, ζ). 3D point cloud data is obtained, but 3D point cloud data (or STL data) may be obtained directly from a plurality of parallel cross-sectional images 7 obtained by imaging.

  Specifically, since the point B and the unit vectors ξ, η, ζ are obtained in the xyz coordinate system (in step S7), each part (inner wall, outer wall, etc.) is created on a plurality of parallel sectional images 7. If the point group (x, y, z) is obtained, it can be converted into coordinates (ξ, η, ζ) and converted into 3D point group data based on the axis HA.

(Modification 8)
In the first embodiment, the load mechanism 4b applies a load by pressing the pressure plate 4c against the ground contact surface (outer peripheral surface) of the tire 2, but there are various ways of applying the load.

  Usually, the pressure plate 4c is parallel to the axis HA, and a force is applied in a direction perpendicular to the pressure plate 4c (left direction in FIG. 1).

  In a test simulating braking (or acceleration), the pressure plate 4c is parallel to the axis HA, and the force is applied while being inclined from the direction perpendicular to the pressure plate 4c in the circumferential direction of the tire 2 (vertical direction in FIG. 1).

  In a test simulating cornering, the pressure plate 4c is parallel to the axis HA, and the force is applied while being inclined in the direction of the axis HA from a direction perpendicular to the pressure plate 4c.

  Further, when simulating the case where the axis HA is not parallel to the ground (inclination at the time of cornering, inclination arrangement of the front wheels, etc.), the pressure plate 4c is inclined from the parallel to the axis HA (rotated about an axis parallel to the z axis). In this state, a load is applied in a direction perpendicular to the pressure plate 4c or in a direction inclined from the perpendicular direction.

  Furthermore, the load can be applied by arbitrarily combining braking (or acceleration), cornering, and the case where the axis HA is not parallel to the ground.

(Modification 9)
In the first embodiment, the plurality of obtained cross-sectional images 11-i inclined with respect to each other can be regarded as time-series multi-sectional images when the tire rotates with respect to one cross-section fixed to the tire. There are some differences along the circumference (such as the groove pattern of the tread 14) in the cross-sections at different locations.

  On the other hand, it is possible to photograph changes in time-series cross-sectional images when exactly the same cross-section is rotated.

  For this purpose, when the wheel 3 is fixed to the holder 4a, the wheel 3 is fixed via a bearing so as to be rotatable about the wheel axis HA. Then, the rotation position φj of the tire 2 is fixed, and a plurality of inclined cross-sectional images 11-i are obtained by performing the same scanning and cross-sectional conversion as in the first embodiment. Here, the inclination angle θi of the cross-sectional image 11-i is set to an equal pitch of Δθ.

  Next, the rotational position φj is changed by Δθ, and a plurality of inclined cross-sectional images 11-i are obtained respectively. A plurality of sets of cross-sectional images 11-i (3D data) with φj changed are a plurality of sets of 3D data obtained by following the rotation of the tire with a pitch Δθ. A time-series cross-sectional image is obtained.

(Modification 10)
In the first embodiment, the CT unit 5 is the CT unit 5 of the single-row detector (one section / one scan) in the TR method, but the CT unit 5 may be in other methods.

  For example, as a TR system of a multi-row detector, a CT unit that obtains a plurality of parallel sectional images by one scan may be used. Further, in the case of multiple rows, a parallel z-sectional image in a wide z range can be obtained with a small number of scans by moving a plurality of scans with z movement.

  Further, the CT unit may be an RR type that is not only the TR type but only the rotation, and the detector in this case may be one or more rows. In the case of one row, z is moved and scanned to obtain a plurality of parallel sectional images, and in the case of multiple rows, a plurality of parallel sectional images are obtained by one scan. In the case of multiple rows, a parallel z-section image in a wide z range can be obtained with a small number of scans by moving a plurality of scans with z movement.

(Modification 11)
In the first embodiment, X-rays are used, but X-rays may be other transmissive radiation. For example, γ rays or neutron rays may be used.

DESCRIPTION OF SYMBOLS 1 ... Tire inspection apparatus, 2 ... Tire, 2a, 2b ... Tire sectional image, 3 ... Wheel, 4 ... Load mechanism part, 4a ... Holder, 4b ... Load mechanism, 4c ... Pressure plate, 5 ... CT part, 5a ... X Radiation source, 5b ... X-ray detector, 5c ... Rotation / translation mechanism, 5d, 5e ... Elevating mechanism, 5f ... X-ray, 5g ... Control processing unit, 6 ... Image processing unit, 7, 7a, 7b, 7c ... Cross-sectional image, 8 ... wheel end face, 9a, 9b ... plane, 10 ... reference plane, 10-i ... inclined surface, 11-i ... cross-sectional image, 12, 12a, 12b ... bead, 13, 13a, 13b ... inner wall, 14 , 14a, 14b ... tread, 15 ... circle TP ... imaging surface, HA ... wheel rotation axis, RA ... CT rotation axis, [theta] i ... inclination angle,
DESCRIPTION OF SYMBOLS 101 ... Tire, 102 ... Wheel, 103 ... Holder, 104 ... Load mechanism, 105 ... Pressure plate, 106 ... Support stand, 107 ... Inclination drive part, 108 ... CT part, 109 ... Position of cross-sectional image

Claims (5)

Load means for applying a load by pressing a pressure plate against the ground surface against a tire that is mounted and held on a wheel and whose internal air is pressurized,
CT means for photographing the loaded tire and photographing a plurality of parallel sectional images;
From the plurality of parallel cross-sectional images, wheel cross-sectional images corresponding to at least two planes parallel to the end surface in the rotation axis direction of the wheel are respectively obtained, and the center coordinates of the wheel are determined on the obtained wheel cross-sectional images. Finding the position of the rotation axis of the wheel as a line connecting the obtained center coordinates of the wheel, respectively, converting the plurality of mutually parallel cross-sectional images into a plurality of mutually inclined sections passing through the rotation axis of the wheel An image processing unit that creates images
A tire inspection apparatus comprising: A plurality of parallel cross-sectional images obtained by photographing a tire loaded and held on a wheel and pressurized with internal air being pressurized and a pressure plate pressed against a ground contact surface by a load means , From each of the cross-sectional images parallel to each other, obtain a cross-sectional image of the wheel corresponding to at least two planes parallel to the end surface in the rotation axis direction of the wheel, respectively, determine the central coordinates of the wheel on the obtained cross-sectional image of the wheel, The position of the rotational axis of the wheel is obtained as a line connecting the obtained center coordinates of the wheel, and a plurality of mutually inclined cross-sectional images passing through the rotational axis of the wheel are formed by converting a cross-section from the plurality of parallel cross-sectional images. A tire inspection apparatus having an image processing unit. In the tire inspection apparatus according to claim 1 or 2 ,
The image processing unit folds two tire cross-sectional images sandwiching the rotation axis of the wheel, one of the plurality of inclined cross-sectional images passing through the rotation axis of the wheel, with the rotation axis of the wheel. A tire inspecting apparatus characterized in that it displays overlapping each other, or obtains the amount of deviation of each other when one of them is folded back by the rotation axis of the wheel and overlapped with each other. In the tire inspection apparatus according to claim 1 or 2 ,
The image processing unit fits a predetermined part by shifting two tire cross-sectional images sandwiching the rotation axis of the wheel in one of a plurality of inclined cross-sectional images passing through the rotation axis of the wheel. A tire inspection apparatus characterized in that the amount of overlap is calculated when overlapping and displaying, or by shifting a predetermined part to fit each other and overlapping. In the tire inspection apparatus according to claim 1 or 2 ,
The image processing unit uses a plurality of mutually inclined cross-sectional images passing through the rotation axis of the wheel to obtain a deformation with respect to the rotation axis of the wheel for a ring formed by a predetermined portion of the tire. Inspection device.

Images