Device and method for testing a tire, in particular by means of an interferometric measuring method

Abstract

A device (10) for testing tires (100) using an interferometric measuring method comprises a pressure chamber (20) in which the tire (100) to be tested is subjected to a predetermined pressure (ρ ND , ρ PDThe tire (100) is a substructure (30) on which it can be stored lying down, and a measuring device (40). The tire (100) has a first sidewall (110), a second sidewall (120) and a tread (130), each of which can be subdivided into a plurality of sectors to be measured (S1.1 to S1.4; S2.1 to S2.4; L1 to L8), each of which is bounded by two sector lines (SL1.1-A1 to SL2.4-A2; SL1-L1 to SL8-L2) which are at a predetermined sector angle (α, β) to each other. The measuring device (40) has N external measuring heads (42) configured to detect a sector (S1.1 to S1.4; S2.1 to S2.4) of the first side wall (110) and / or the second side wall (120), and N internal measuring heads (44) configured to detect a sector (L1 to L8) of the running surface (130). N is a natural number.The device comprises a rotary device (32, 46) for rotating the base (30) and / or the measuring device (40) by a predetermined rotation angle (φ-DA). The device is characterized in that the first sector angle (α) has the value of the formula: . 360° N ⋅ 2 exhibits; and that the second sector angle (β) has the value of the formula: 360° N ⋅ 4 exhibits. The size of the rotation angle (φ-DA) corresponds to the value of the first sector angle (α).

Description

[0001] The invention relates to a device and a method for testing a tire, in particular by means of an interferometric measuring method.

[0002] A tire is a rotationally symmetric component, so the device according to the invention is also suitable for testing other rotationally symmetric components. The measurement method used to test the tires is, in particular, an interferometric, preferably a so-called shearographic, measurement method.

[0003] In industrial practice, optical measurement methods such as holography or shearography, also known as speckle pattern shearing interferometry, are often used in the non-destructive testing of tires. Shearography is a relative interferometric measurement method that produces an image representing the difference between two temporally offset states of the test object. To create the different states between two measurements, the test object is brought into a changed state by exerting a mechanical, thermal, or pneumatic force on it. For this reason, known devices have a pressure chamber that is either evacuated or pressurized, so that the test object located in the pressure chamber deforms as a result of the pressure change. In this process, the test object transitions from a first reference state to a second measurement state.

[0004] Based on images of the test object in two different states, the relative interferometric measurement method can be used to determine the deformation gradient. The shearogram, which characterizes the deformation gradient, is generated by subtracting the intensities of the interferograms obtained in the reference state and the measurement state. The shearogram indicates whether the position of a point relative to a neighboring point has changed due to the deformation of the test object. If so, this path difference leads to a local change in the intensity distribution, which provides information about a defect. Interferometric measurement methods based on this speckle interferometry are known, for example, from DE 42 31 578 A1 and EP 1 014 036 B1.

[0005] Due to the complex measurement procedure, the duration of a test cycle is relatively long, as the pressure chamber must be pressurized several times. A test cycle comprises at least two measurements, each performed at a different ambient pressure. These measurements must be repeated several times, as the area detected by a sensor can only cover a portion of the test object. Accordingly, a device is known from EP 1 959 227 B1, for example, that measures the tire section by section using a measuring head in a test cycle. However, in order for the tire to be fully measured, the tire must be rotated intermittently, and the pressure chamber must be evacuated several times.

[0006] To reduce the cycle time of a testing system, existing machines use more measuring systems / cameras to capture more sectors or tire sections simultaneously. Such a device is known, for example, from EP 2 549 258 B1 and DE 10 2013 010 402 A1. However, these measuring systems are expensive and very sensitive, requiring high levels of maintenance. Furthermore, the light sources (e.g., laser diodes) and optics of such measuring heads are subject to wear, so keeping the number of measuring heads as low as possible is desirable.

[0007] With the ongoing development of new, highly sensitive digital cameras that feature a so-called CMOS sensor, larger fields of view can be captured without any loss of image quality compared to previous camera systems with a so-called CCD sensor.

[0008] In principle, a larger field of view can reduce the number of sectors to be inspected, thereby also reducing the duration of the entire inspection without increasing the number of measuring systems. However, despite the technically larger field of view, the maximum area that can be captured is usually limited by the distance to the surface to be measured. In order to perform a measurement inside a tire, the shorter available distance must be compensated for by a shorter focal length. However, with a shorter focal length, the captured image is particularly distorted in the edge area, which means that the edge area is only suitable to a limited extent for testing a tire using an interferometric measuring method.

[0009] The invention is based on the object of creating a device for testing tires, in particular by means of an interferometric measuring method, and a corresponding method by means of which a relatively short testing time can be achieved.

[0010] This object is achieved by a device according to claim 1 and a method according to claim 13.

[0011] Preferred embodiments of the device are the subject of claims 2 to 12, and advantageous embodiments of the method are the subject of claims 14 and 15.

[0012] The device according to the invention for testing a tire by means of an interferometric measuring method comprises a pressure chamber, a base frame, a measuring device with N external measuring heads and N internal measuring heads, and a rotating device.

[0013] The tire has a first sidewall, a second sidewall, and a tread. The first sidewall and / or the second sidewall can be divided into a plurality of sectors to be detected. The sectors of the first sidewall are delimited by a first sector line and a second sector line. The sectors of the second sidewall are delimited by a first sector line and a second sector line. The first sector line and the second sector line delimiting the respective sector are at a sector angle to one another. The tread can be divided into a plurality of sectors to be detected. The sectors of the tread are each delimited by a first sector line and a second sector line. The first sector line and the second sector line delimiting the respective sector are at a second sector angle to one another.

[0014] The pressure chamber is designed to expose the tire to be tested to a specified pressure.

[0015] With the help of the underframe, the tire can be stored lying down so that the first sidewall is on top in a first test cycle and, after turning the tire, the second sidewall is on top in a second test cycle.

[0016] The measuring device comprises N outer measuring heads and N inner measuring heads. The N outer measuring heads are each designed to completely cover a sector of the first sidewall and / or the second sidewall. The N inner measuring heads are each designed to completely cover a sector of the tread. N is a natural number.

[0017] The rotating device is designed to rotate a surface of the undercarriage on which the tire lies and / or the measuring device by a predetermined angle of rotation about a rotation axis.

[0018] The device according to the invention is characterized in that the first sector angle has the value of the formula: 360°N⋅2 and the second sector angle the value of the formula: 360°N⋅4 The size of the rotation angle corresponds to the value of the first sector angle.

[0019] The size of the sector covered by a measuring head is defined by the number of measuring heads, with the number of outer measuring heads and the number of inner measuring heads being equal. According to the invention, the outer measuring heads are designed such that they cover sectors with a sector angle that corresponds to twice the sector angle of a sector covered by an inner measuring head.

[0020] By defining the sector size relative to the number of measuring heads, it is possible to perform a test cycle with only one pressure change and one rotation of the sectors relative to the measuring heads. In a first test cycle, the entire sidewall on one side of the tire and half of the tread sectors are scanned. In a second test cycle, the entire sidewall on the other side of the tire and the other half of the tread sectors are scanned. After completing the first test cycle and the second test cycle, the tire is fully tested.

[0021] The total test time required for testing a tire is reduced to a minimum in a particularly advantageous manner due to the special definition of the dimensions of the sector size.

[0022] A particularly advantageous relationship between the resolution of the detected sectors and the number of measuring heads required for this purpose results from a device in which the variable N is equal to 2 or 3. Such a device has two or three external measuring heads and two or three internal measuring heads.

[0023] A device with a variable N equal to 1 requires a relatively large sector angle. This distorts the measurement result in the edge area. However, with a sufficiently large tire, this can still lead to a sufficiently good measurement result, so the advantage of the additional reduction in the number of measuring heads is worth emphasizing.

[0024] A device where the variable N is greater than 2 or 3, for example, 4 or 5 or 6 or more, requires relatively high maintenance and calibration effort. Furthermore, positioning the measuring heads becomes more complex as the number increases. However, a corresponding device with comparatively small measuring heads and simple calibration is easily feasible in a specific application.

[0025] In an advantageous further development, the base frame or the measuring device comprises the rotating device. A rotating device arranged in the base frame, such as a turntable, enables a simple construction of the measuring device, since the cables connected to the measuring heads do not have to be pulled along via a cable chain or a cable drag chain. In contrast, a rotating device arranged on the measuring device has the advantage that few vibrations are introduced into the tire. However, it should be noted that rotating the measuring heads can also introduce vibration into the measuring device and thus the measuring device must always be allowed to oscillate before further measurements can be taken.

[0026] Advantageously, the rotation device is designed to rotate the tire or the measuring device during the test cycle. This is particularly advantageous while the pressure chamber is at a test pressure, as it eliminates the need to establish nominal pressure prior to rotation, eliminating the need to evacuate or pressurize the pressure chamber again.

[0027] Advantageously, the internal measuring head and / or the external measuring head have a detection range that is larger than the sector to be detected. This is because the detection range is determined by a variety of factors, such as the distance to the area to be detected, the focal length, and the sensor size of the measuring head. The shape of the sensor, which is usually rectangular, can also influence the detection range. Accordingly, an overlap area can occur between two adjacent, detected sectors in the detection range. In a subsequent step, the area surrounding the sector can be removed, thereby eliminating overlap areas.

[0028] In a further preferred embodiment, the first sector line of the first sector of the first sidewall and / or the second sidewall is at a predetermined angle to the first sector line of the first sector of the tread. It is particularly preferred if the angle is zero. This results in a particularly simple assembly of the sectors acquired by a measuring head in the subsequent image processing. In particular, the geometrically defined assignment of the sectors significantly reduces the computational effort in the subsequent image processing. The acquired sectors can be assembled relatively easily, without the aid of a reference point in the images themselves.

[0029] The device advantageously comprises a turning device which is designed to turn the tire to be tested about a turning axis. It has proven advantageous if the turning axis and the first sector line of the first sector of the tread are arranged parallel to one another and in a plane, wherein the plane is defined by the sector line of the first sector. By turning the tire about a turning axis which is in such a direct relationship to the arrangement of the sectors of the tread, the tire can be not only turned but also aligned at the same time, so that separate alignment of the measuring heads relative to the sectors is no longer necessary. Due to the simultaneous alignment of the measuring heads relative to the sectors to be measured during turning, additional time is saved.

[0030] It should be added that the plane is defined by the sector line, since the sector line can assume various positions along the tire's rotational axis. The turning axis is thus arranged along the tire's cross-section, which runs along the sector line. It is particularly preferred if the turning axis and the first sector line of the first sector of the tread are coaxial.

[0031] Furthermore, it is preferred that a first alignment line running between two adjacent outer measuring heads, viewed from above, is at an angle (the alignment angle) to a second alignment line running between two adjacent inner measuring heads. This angle is advantageously half the sector angle of the tread sector. Since the measuring heads are usually arranged centrally relative to the sector to be measured, the outer measuring heads can be arranged rotated relative to the inner measuring heads. In a device with two outer measuring heads and two inner measuring heads, the angle between the alignment lines is 22.5°.

[0032] Advantageously, the number of sectors of the first sidewall is 4 or 6. Further advantageously, the number of sectors of the tread is 8 or 12. Further preferred is the number of sectors of the second sidewall is 4 or 6. However, the number of sectors is defined by the number of measuring heads.

[0033] A further aspect of the invention is directed to a method for testing a tire using the testing device according to the invention.

[0034] The method for testing the tire comprises the following steps: a) placing the tire to be tested in a horizontal position in the pressure chamber; b) performing a first test cycle to detect all sectors of the first sidewall and a predetermined number of sectors in a first detection area of ​​the tread; c) turning the tire over; and d) performing a second test cycle to detect all sectors of the second sidewall and a predetermined number of sectors in a second detection area of ​​the tread. The first detection area and the second detection area together comprise all sectors of the tread.

[0035] The procedure is characterized by the fact that the entire tire can be recorded and tested in two test cycles.

[0036] The detection area comprises several sectors, which, however, do not have to be arranged adjacent to one another. Rather, the detected sectors are preferably evenly distributed along the circumference of the tire.

[0037] A test cycle may, for example, comprise the following steps: a) positioning the measuring heads in a test position; b) detecting the sectors assigned to the measuring heads; c) generating a test pressure in the pressure chamber; d) detecting the sectors assigned to the measuring heads; e) rotating the base frame and / or the measuring heads about a rotation axis; f) detecting the sectors assigned to the measuring heads; g) establishing a nominal pressure in the pressure chamber; h) detecting the sectors assigned to the measuring heads; and i) positioning the measuring heads in a standby position.

[0038] A nominal pressure corresponds, for example, to the air pressure surrounding the device, which is usually atmospheric pressure and amounts to approximately 1 bar. The test pressure can be a negative pressure generated by evacuating the pressure chamber and corresponds, for example, to 0.5 to 0.7 bar.

[0039] During a measurement, the measuring head measures a slightly larger area than the sector to be captured, so that a portion of the measured area in one sector overlaps with a portion of the measured area in an adjacent sector. The overlapping area is removed from the measured areas during a subsequent processing step using image processing software, resulting in a seamlessly combined measurement image.

[0040] In an advantageous embodiment of the test cycle, the tire or the measuring heads are rotated by 60°, 90°, or 180° during step e). A 60° rotation occurs with a device with three external measuring heads and three internal measuring heads. A 90° rotation occurs with a device with two external measuring heads and two internal measuring heads. A 180° rotation occurs with a device with one external measuring head and one internal measuring head.

[0041] The device for testing a tire according to the invention, as well as further features and advantages of the invention, are explained in more detail below using exemplary embodiments schematically illustrated in the figures. Herein: Fig. 1 is a side view of a device for testing a tire in a first embodiment; Fig. 2 a tire; Fig. 3 a cross-section through a tire along the line III-III of Fig. 2; Fig. 4a is a plan view of the tire testing apparatus in the first embodiment; Fig. 4b is a plan view of the device for testing a tire in a second embodiment; Fig. 5 is a side view of the device for testing a tire during a first test cycle, a tire turn, and a second test cycle; Fig. 6a the tyre and the measuring heads during a first test cycle before a single rotation of the tyre; Fig. 6b the tire and the measuring heads of Fig. 6a time after a single rotation of the tire; Fig. 6c the tire of Fig. 6b during turning of the tire; Fig. 6d the tire of Fig. 6c during a second test cycle before a single rotation of the tyre; Fig. 6e the tire of Fig. 6d during a second test cycle after a single rotation of the tyre; Fig. 7a the arrangement of the sectors to be detected in the first test cycle; Fig. 7b the arrangement of the sectors to be detected in the second test cycle and Fig. 8 the pressure conditions in the pressure chamber during the first or second test cycle.

[0042] Fig. Figure 1 shows a device 10 for testing a tire 100 using an interferometric measuring method. The device 10 comprises a pressure chamber 20, a base frame 30, a measuring device 40 having a plurality of measuring heads 42a, 42b, 44a, 44b, and a Fig. 1 turning device 50 not shown.

[0043] The tire 100 to be tested is in Fig. 2 and Fig. 3 in more detail. The tire 100 has a first sidewall 110, a second sidewall 120, and a tread 130. A first bead 115 is located at the radially inner end of the first sidewall 110. A second bead 125 is located at the radially inner end of the second sidewall 120. The tire 100 is rotationally symmetrical about a rotational axis RA of the tire 100.

[0044] The first sidewall 110, the second sidewall 120 and the tread 130 are divided into a plurality of sectors. Fig. 6a to 6e and 7a and 7b show an exemplary subdivision of the tire 100, which results from a device 10 with two external measuring heads 42a, 42b and two internal measuring heads 44a, 44b.

[0045] The first sidewall 110 and the second sidewall 120 are each divided into four sectors S1.1 to S1.4 and S2.1 to S2.4. The tread 130 is divided into eight sectors L1 to L8. The sectors of the first sidewall 110 and the second sidewall 120 are each of the same size. The sectors of the tread 130 are also each of the same size.

[0046] The sectors S1.1 to S1.4 of the first sidewall 110 are each delimited by a first sector line SL1.1-A1 to SL1.4-A1 and a second sector line SL1.1-A2 to SL1.4-A2. In the present example, the first sector line SL1.1-A1 to SL1.4-A1 is arranged clockwise in front of the second sector line SL1.1-A2 to SL1.4-A2 in a top view of the tire 100. Each sector line SL1.1-A1 to SL1.4-A1, SL1.1-A2 to SL1.4-A2 intersects the rotation axis RA of the tire 100. The first sector line SL1.1-A1 to SL1.4-A1 is at a first sector angle α relative to the second sector line SL1.1-A2 to SL1.4-A2 of a common sector S1.1 to S1.4. The sector lines SL2.1-A1 to SL2.4-A1, SL2.1-A2 to SL2.4-A2 of the second side wall 120 are arranged distributed correspondingly to the sector lines SL1.1-A1 to SL1.4-A1, SL1.1-A2 to SL1.4-A2 of the first side wall 110.

[0047] The sectors L1 to L8 of the tread 130 are each delimited by a first sector line SL1-L1 to SL8-L1 and a second sector line SL1-L2 to SL1-L2. In the present example, the first sector line SL1-L1 to SL8-L1 is arranged clockwise in front of the second sector line SL1-L2 to SL8-L2 in a top view of the tire 100. Each sector line SL1-L1 to SL8-L1, SL1-L2 to SL8-L2 intersects the rotation axis RA of the tire 100. The first sector line SL1-L1 to SL8-L1 is at a second sector angle β relative to the second sector line SL1-L2 to SL8-L2 of a common sector L1 to L8.

[0048] The pressure chamber 20 comprises access areas through which the tire 100 can be conveyed into the pressure chamber 20, usually on a conveyor belt. The access areas can be closed, so that the pressure chamber 20 forms a hermetically sealed space in which the tire 100 can be tested. Furthermore, the pressure chamber 20 has a vacuum pump (not shown) that is designed to evacuate the pressure chamber 20. Air is pumped out of the pressure chamber 20 by means of the vacuum pump until a test pressure ρ PD is reached. The outlet pressure in the pressure chamber 20 is a nominal pressure ρ ND, which in the present embodiment is defined by the atmospheric pressure surrounding the device 10. As soon as a new tire 100 is conveyed into the pressure chamber 20, the access areas are opened, so that an atmospheric pressure is inevitably established in the pressure chamber 20 at this time. However, before the first measurement, this atmospheric pressure could be reduced to a different nominal pressure ρ by means of the vacuum pump. ND However, in practice it has been shown that a constant atmospheric pressure can be used as the nominal pressure ρ ND suitable.

[0049] The base frame 30 is arranged in the pressure chamber 20 and is connected to a conveyor belt such that a tire 100 can be directly transferred for testing. In the embodiment shown, the base frame 30 has a rotating device 32. The rotating device 32 enables rotation about a rotation axis DA of the tire 100 lying on the base frame 30 by a predetermined rotation angle φ-DA, as is shown, for example, in Fig. 4b. The rotation axis DA is arranged perpendicular to a surface 31 of the base frame 30 on which the tire 100 rests. Furthermore, the rotation axis DA preferably intersects the center of the base frame 30.

[0050] The measuring device 40 comprises in the Fig. 1 illustrated embodiment, two external measuring heads 42a, 42b, two internal measuring heads 44a, 44b and a rotating device 46.

[0051] The outer measuring heads 42a, 42b and the inner measuring heads 44a, 44b are connected to a mounting unit 48. The mounting unit 48 is designed to move the outer measuring heads 42a, 42b and the inner measuring heads 44a, 44b from a standby position to a test position. In the standby position, the outer measuring heads 42a, 42b and the inner measuring heads 44a, 44b are arranged above the tire 100 so that the tire 100 can be conveyed into and out of the pressure chamber 20. In the test position, the outer measuring heads 42a, 42b and the inner measuring heads 44a, 44b are arranged such that they can measure the respective sector of the tire 100 to be detected. The distribution of the sectors is described in more detail below. In addition to adjustment in the vertical direction, the measuring heads 42a, 42b, 44a, 44b can also be adjusted in at least the horizontal direction.For this purpose, the mounting unit 48 comprises rails 49. The rails 49 for the respective measuring heads 42a, 42b, 44a, 44b can be designed separately from one another. In this case, it is possible to position the rails 49 at an angle relative to one another. Fig. 1 shows a possible design of a one-piece rail system. Fig. 4a and Fig. 4b show, in an alternative embodiment, a rail system having a separate rail 49 for each measuring head 42a, 42b, 44a, 44b. In this embodiment, the inner measuring heads 44a, 44b are additionally connected to rails 49 that are arranged at an alignment angle γ relative to the rails 49 connected to the outer measuring heads 42a, 42b. As a result, the outer measuring heads 42a, 42b are arranged along a first alignment line AL1, and the inner measuring heads 44a, 44b are arranged along a second alignment line AL2. The first alignment line AL1 is thus also arranged at an alignment angle γ relative to the second alignment line AL2.

[0052] The rotating device 46 is designed to rotate the measuring heads 42a, 42b, 44a, 44b about a rotation axis DA by a rotation angle φ-DA, as shown in Fig. 4a. The rotation axis DA is arranged perpendicular to the surface 31. Preferably, the rotation axis DA is arranged coaxially with the rotation axis RA of the tire 100 during a test. The device 10 in the Fig. The embodiment shown in Figure 1 comprises both a rotating device 46 for rotating the measuring heads 42a, 42b, 44a, 44b and a rotating device 32 for rotating the tire 100 lying on the base frame 30. In practice, however, it is generally sufficient to provide only one rotating device 32, 46, whereby the rotating device 32 for rotating the tire lying on the base frame 30 has so far proven to be the more reliable embodiment.

[0053] The turning device 50 is not shown in detail in the drawings. Fig. 5 and Fig. Figure 6c illustrates the turning process performed by the turning device 50. The turning device 50 turns the tire 100 about a turning axis WA, so that the previously lower second sidewall 120 is on top after the turning process. Similarly, the previously upper first sidewall 110 is on the bottom after the turning process. The turning axis WA is arranged perpendicular to the rotation axis RA.

[0054] It should be emphasized that the turning axis WA runs coaxially with the first sector line SL1.1-A1 of the first sector L1 of the tread 130. This makes it possible in a simple manner to mirror the arrangement of the sectors L1 to L8 of the tread 130 simply by turning the tire 100. The mirroring is obtained by comparing the arrangement of the sectors L1 to L8 of the tread 130 in a top view of the tire 100 before turning with the arrangement of the sectors L1 to L8 of the tread 130 in a top view of the tire 100 after turning.

[0055] The test of tire 100 includes the following steps.

[0056] In a first step S1, the tire 100 is placed in a horizontal position in the pressure chamber 20. The tire 100 is in a horizontal position when the tire 100 rests on the first sidewall 110 or the second sidewall 120 on the base frame 30, such as a conveyor belt.

[0057] In a second step S2, a first test cycle PZ1 is performed. This involves scanning all sectors S1.1 to S1.4 of the upper first sidewall 110 and a first detection area EB1 of the tread 130. The first detection area EB1 comprises half of the sectors L1 to L8 of the tread 130.

[0058] In a third step S3, the tire 100 is conveyed from the pressure chamber 20 to a turning device 50, where it is turned around the turning axis WA. After turning, the tire 100 is conveyed back into the pressure chamber 20 lying on the first sidewall 110.

[0059] In a fourth step S4, a second test cycle PZ2 is performed. This involves scanning all sectors S2.1 to S2.4 of the upper second sidewall 120 and a second detection area EB2 of the tread 130. The second detection area EB2 comprises half of the sectors L1 to L8 of the tread 130, which differ from the sectors L1 to L8 of the first detection area EB1. The first detection area EB1 and the second detection area EB2 together comprise all sectors L1 to L8 of the tread 130.

[0060] The respective sectors of a detection area EB can, as in Fig. 7a and Fig. 7b, distributed over the tire 100. The selection of a first detection area EB1 is described below using the sectors L1 to L8 of the tread 130 as an example. The sectors L1 to L8 of the tread 130 are, as shown in Fig. 7a, arranged side by side according to the numbering in ascending order. First, the sectors L1 and L5 are measured, followed by the sectors L3 and L7 after a rotation of the tire 100 around the rotation axis RA. The sectors L2, L4, L6 and L8 are then measured as shown in Fig. 7b, detected by a second detection area EB2.

[0061] In the example shown, the sectors simultaneously detected are arranged opposite each other and thus evenly distributed. However, an alternative arrangement is also conceivable, for example, in which the sectors covered by a detection area are at least partially adjacent to each other. However, this configuration is not shown in the drawings.

[0062] Furthermore, the sectors of the sidewalls 110, 120 are arranged in a distributed manner similar to the previously mentioned example. However, the sectors of the first sidewall 110 or the second sidewall 120 are each completely covered by a detection area EB1 or EB2, whereas the sectors of the tread 130 are only half covered by the first detection area EB1 or the second detection area EB2.

[0063] After completing the test cycle, the tire 100 is fully measured.

[0064] The previously described first test cycle PZ1 and the second test cycle PZ2 are in Fig. 8. The test cycle PZ1, PZ2 comprises the following steps.

[0065] In a first step S1 PZ The measuring heads 42a, 42b, 44a, 44b are brought into a test position. The measuring heads 42a, 42b, 44a, 44b in a possible test position are, for example, in Fig. 1 and Fig. 5. It should be emphasized here that the internal measuring heads 44a, 44b are positioned at a distance from the sector of the tread 130 to be measured, which distance is determined by the size of the tire 100.

[0066] In a second step S2 PZ , which is carried out at time t1.1, the measuring heads 42a, 42b, 44a, 44b record the respectively assigned sector. This measurement takes place while the nominal pressure ρ ND is present.

[0067] In a third step S3 PZ the pressure chamber 20 is evacuated until a test pressure ρ PD is reached. The test pressure ρ PD is sufficiently below the nominal pressure ρ ND to perform an interferometric measurement.

[0068] In a fourth step S4 PZ , which is carried out at time t1.2, the measuring heads 42a, 42b, 44a, 44b detect the respectively assigned sector, which corresponds to the sector of the second step S2PZ measured sector. This measurement is carried out while the test pressure ρ PD is present.

[0069] In a fifth step S5 PZThe base frame 30 or the measuring device 40 is rotated about the rotation axis DA, which runs coaxially with the rotation axis RA of the tire 100. In the present embodiment with two external measuring heads 42a, 42b and two internal measuring heads 44a, 44b, the tire 100 is rotated by 90° relative to the measuring heads 42a, 42b, 44a, 44b. In a device with three external measuring heads 42a, 42b and three internal measuring heads 44a, 44b, the tire 100 is rotated by 60° relative to the measuring heads 42a, 42b, 44a, 44b. In a device with an external measuring head 42a, 42b and an internal measuring head 44a, 44b, the tire 100 is rotated by 180° relative to the measuring heads 42a, 42b, 44a, 44b. The rotation takes place while the test pressure ρ PD is present.

[0070] In a sixth step S6 PZ, which is carried out at time t2.1, the measuring heads 42a, 42b, 44a, 44b record the respectively assigned sector. This measurement is carried out while the test pressure ρ PD is present.

[0071] In a seventh step S7 PZ in the pressure chamber 20 the nominal pressure ρ ND restored.

[0072] In an eighth step S8 PZ , which is carried out at time t2.2, the measuring heads 42a, 42b, 44a, 44b detect the respectively assigned sector, which corresponds to the sector of the sixth step S6 PZ measured sector. This measurement is carried out while the nominal pressure ρ ND is present.

[0073] In a ninth step S9 PZ the measuring heads 42a, 42b, 44a, 44b are brought into the standby position so that the tire 100 can be conveyed out of the pressure chamber 20 again.

[0074] The sectors S1.1 to S1.4, L1, L3, L5, L7 recorded in the first test cycle PZ1 are in Fig. 7a. The sectors shown in the inner circle correspond to the sectors distributed on the tread 130, and the sectors arranged in the radially outer circle correspond to the sectors of the first sidewall 110. For clarity, the sectors of the tread 130 below are shown in a "folded out" or "rolled out" manner.

[0075] The sectors S2.1 to S2.4, L8, L6, L4, L2 recorded in the second test cycle PZ2 are in Fig. 7b.

[0076] Since in each test cycle PZ1, PZ2 all sectors of the first sidewall 110 or the second sidewall 120 are detected and the sectors of the tread 130 only half, the arrangement of the turning axis WA relative to the sectors to be detected of the inner measuring heads 44a, 44b is crucial in order to avoid a subsequent adjustment of the alignment of the tire 100.

[0077] For this purpose, in the present embodiment, the turning axis WA is arranged coaxially with the first sector line SL1-L1 of the first sector L1 of the running surface 130. It should also be noted that with a measuring head arranged centrally relative to the sector to be measured, subsequent machining can also be reduced.

[0078] The described device 10 is characterized in that, in particular, only two or three external measuring heads 42a, 42b and two or three internal measuring heads 44a, 44b are required. The particular ratio of the size of the sectors detected by the external measuring heads relative to the size of the sectors detected by the internal measuring heads is crucial here. As previously described, the size of the sectors detected by the external measuring heads is defined by the first sector angle α, and the size of the sectors detected by the internal measuring heads is defined by the second sector angle β. The first sector angle α is twice as large as the second sector angle β.

[0079] The device 10 thus enables the complete testing of the tire 100 in only two test cycles PZ1, PZ2, with each test cycle comprising only one rotation of the tire 100. This enables the particularly fast and short test time for the complete testing of the tire 100. List of reference symbols 10 Device 20 pressure chamber 30 base frame 31 Surface 32 Rotating device φ-RA rotation angle φ-DA rotation angle 40 measuring device 42a, 42b external measuring heads 44a, 44b internal measuring heads 46 Rotating device 46DA Rotation axis of the rotating device 48 fastening unit 49 Rail 50 turning device N natural number greater than or equal to 2 DA rotation axis WA turning axis AL1 first alignment line AL2 second alignment line γ orientation angle ρ ND Nominal pressure ρ PD Test pressure EB1 first detection area EB2 second detection area 100 tires 110 first side wall 115 first bead 120 second side wall 125 second bead 130 tread S1.1 to S1.4 sectors of the first side wall S2.1 to S2.4 sectors of the second side wall SL1.1-A1 to SL2.4-A1 first sector line SL1.1-A2 to SL2.4-A2 second sector line α first sector angle L1 to L8 sectors of the tread SL1-L1 to SL8-L1 first sector line SL1-L2 to SL8-L2 second sector line β second sector angle δ line angle RA rotation axis PZ1 first test cycle PZ2 second test cycle t1.1 Time of second step; first measurement at nominal pressure t1.2 Time point for fourth step; second measurement at test pressure tD Time point to fifth step; rotation t2.1 Time point for sixth step; third measurement at test pressure t2.2 Time of eighth step; fourth measurement at nominal pressure

Claims

[1] Device (10) for testing tires (100), in particular by means of an interferometric measuring method, wherein the tire to be tested (100) has a first sidewall (110), a second sidewall (120) and a tread (130), wherein the first side wall (110) and / or the second side wall (120) can be divided into a plurality of sectors (S1.1 to S1.4; S2.1 to S2.4) to be detected, wherein the sectors (S1.1 to S1.4) of the first side wall (110) are delimited by a first sector line (SL1.1-A1 to SL1.4-A1) and a second sector line (SL1.1-A2 to SL1.4-A2) and / or the sectors (S2.1 to S2.4) of the second side wall (120) are delimited by a first sector line (SL2.1-A1 to SL2.4-A1) and a second sector line (SL2.1-A2 to SL2.4-A2), wherein the first sector line (SL1.1-A1 to SL1.4-A1, SL2.1-A1 to SL2.4-A1) and the second sector line (SL1.1-A2 to SL1.4-A2, SL2.1-A2 to SL2.4-A2) delimiting the respective sector (S1.1 to S1.4, S2.1 to S2.4) are at a sector angle (α) to each other, wherein the running surface (130) can be divided into a plurality of sectors (L1 to L8) to be detected, wherein the sectors (L1 to L8) of the tread (130) are each delimited by a first sector line (SL1-L1 to SL8-L1) and a second sector line (SL1-L2 to SL8-L2), and wherein the first sector line (SL1-L1 to SL8-L1) and the second sector line (SL1-L2 to SL8-L2) delimiting the respective sector (L1 to L8) are at a second sector angle (β) to each other; wherein the device (10) comprises: a pressure chamber (20) in which the tire (100) to be tested is subjected to a predetermined pressure (ρ ND , ρ PD ) is suspendable; a base frame (30) having a surface (31) on which the tire (100) can be supported in such a way that the first sidewall (110) is on top in a first test cycle (PZ1) and, after turning the tire (100), the second sidewall (120) is on top in a second test cycle (PZ2); a measuring device (40) comprising: N external measuring heads (42) which are each designed to completely detect a sector (S1.1 to S1.4; S2.1 to S2.4) of the first side wall (110) and / or the second side wall (120), N internal measuring heads (44) which are each designed to completely detect a sector (L1 to L8) of the running surface (130), and where N is a natural number; and a rotating device (32, 46) for rotating the surface (31) of the base frame (30) on which the tire (100) lies and / or the measuring device (40) by a predetermined angle of rotation (φ-DA) about a rotation axis (DA), characterized by , that the first sector angle (α) has the value of the formula: 360°N⋅2 and the second sector angle (β) has the value of the formula: 360°N⋅4 wherein the size of the angle of rotation (φ-DA) corresponds to the value of the first sector angle (α). [2] Device according to claim 1, characterized by that N is equal to 2 or 3. [3] Device according to claim 1 or 2, characterized by that the base frame (30) has the rotating device (32) or that the measuring device (40) has the rotating device (46). [4] Device according to claim 3, characterized by that the rotating device (32, 46) is designed to rotate the tire (100) or the measuring device (40) during the first test cycle (PZ1) and / or the second test cycle (PZ2). [5] Device according to one of claims 1 to 4, characterized bythat the internal measuring head (44) and / or the external measuring head (42) has a detection range that is larger than the sector to be detected (S1.1 to S1.4; S2.1 to S2.4; L1 to L8). [6] Device according to one of claims 1 to 5, characterized by that the first sector line (SL1.1-A1, SL2.1-A1) of the first sector (S1.1; S2.1) of the first side wall (110) and / or the second side wall (120) is at a line angle (δ) to the first sector line (SL1-L1) of the first sector (L1) of the tread (130). [7] Device according to claim 6, characterized by that the line angle (δ) is zero. [8] Device according to one of claims 1 to 7, characterized by a turning device (50) which is designed to turn the tire (100) about a turning axis (WA). [9] Device according to claim 8, characterized bythat the turning axis (WA) and the first sector line (SL1-L1) of the first sector (L1) of the running surface (130) are arranged parallel to one another and in a plane, wherein the plane is defined by the sector line (SL1-L1) of the first sector (L1). [10] Device according to claim 8 or 9, characterized by in that a first alignment line (AL1), which runs between two external measuring heads (42), is at an alignment angle (γ) to a second alignment line (AL2), which runs between two internal measuring heads (44); wherein the alignment angle (γ) is preferably an acute angle, more preferably between 1° and 22.5°. [11] Device according to claim 10, characterized by that the alignment angle (γ) is half the sector angle (β) of the sector (L1 to L8) of the tread (130). [12] Device according to one of claims 1 to 11, characterized bythat the number of sectors (S1.1 to S1.4) of the first side wall (110) is equal to 4 or equal to 6 and that the number of sectors (L1 to L8) of the tread (130) is equal to 8 or equal to 12 and that the number of sectors (S2.1 to S2.4) of the second side wall (120) is equal to 4 or equal to 6. [13] Method for testing tires (100) by means of a testing device (10) according to one of claims 1 to 12, the method comprising the following steps: a) placing the tyre (100) to be tested in a lying position in the pressure chamber (20); b) carrying out a first test cycle (PZ1) to detect all sectors (S1.1 to S1.4) of the first sidewall (110) and a predetermined number of sectors (L1 to L8) of the tread (130) in a first detection area (EB1) of the tread (L1 to L8); c) turning the tire (100); and d) carrying out a second test cycle (PZ2) to detect all sectors (S2.1 to S2.4) of the second sidewall (120) and a predetermined number of sectors (L1 to L8) of the tread (130) in a second detection area (EB2) of the tread (L1 to L8); wherein the first detection area (EB1) and the second detection area (EB2) together comprise all sectors (L1 to L8) of the running surface (130). [14] Method according to claim 13, characterized by that the first test cycle (PZ1) and / or the second test cycle (PZ2) has the following sequence of steps: a) positioning the measuring heads (42, 44) in a test position; b) detecting the sectors assigned to the measuring heads (42, 44); c) generating a test pressure (pPD) in the pressure chamber (20); d) detecting the sectors assigned to the measuring heads (42, 44); e) rotating the base frame (30) and / or the measuring heads (42, 44) about the axis of rotation (DA); f) detecting the sectors assigned to the measuring heads (42, 44); g) generating a nominal pressure (pND) in the pressure chamber (20); h) detecting the sectors assigned to the measuring heads (42, 44); and i) Positioning the measuring heads (42, 44) in a standby position. [15] Method according to claim 14, characterized by that the tire (100) or the measuring heads (42, 44) are rotated by 60° or by 90° or by 180° during step e).

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