A sheet metal trimming auxiliary measurement device and a measurement method thereof

Abstract

The present invention discloses a sheet metal trimming auxiliary measurement device and a measurement method thereof, the measurement device comprising: a measurement body, comprising a cylinder with an opening, the opening being formed by enclosing the area from the axis of the cylinder to the circumferential surface, thereby forming two measurement surfaces in the longitudinal section of the cylinder; at least one magnetic strip, arranged in the measurement body near one of the two measurement surfaces along the axis of the cylinder; wherein the cross section of the measurement body is in a first sector shape, the cross section of the opening is in a second sector shape, the sum of the central angles of the first and second sectors is 360°, and the central angle of the first sector is greater than 180°. The present invention ingeniously converts the sheet metal trimming that is difficult to detect into the measurement of the cylindrical surface, reduces the shooting and scanning time, and improves the measurement efficiency. At the same time, many previously inaccessible corner features are now accessible, which improves the detection accuracy and accessibility.

Description

Technical Field

[0001] The invention relates to the field of metal stamping detection, in particular to a sheet metal trimming auxiliary measurement device and a measurement method thereof. Background Art

[0002] In the process of automobile manufacturing, the main design and manufacturing method of the body frame is still based on metal sheet stamping followed by welding or riveting. From sheet metal stamping single pieces to sub-assemblies, and then splicing into the final body-in-white assembly, in this process, the size monitoring of the body sheet metal is particularly important. Whether the size is qualified or not will directly affect the installation and matching of the subsequent interior and exterior trims, four doors and two covers, and other functional modules.

[0003] However, in the process of sheet metal size monitoring, the measurement and detection of trimming dimensions has always been a major problem that has plagued the industry, especially when the material is thin or multiple layers of sheet metal are stacked together.

[0004] Figure 1(a) shows a common scene of multi-layer sheet metal stacking on a car body, and Figure 1(b) is a partial enlarged schematic diagram. Under such inspection conditions, it is difficult for current optical automatic measuring machines to balance accuracy and efficiency, resulting in loss of measurement accuracy or even inability to measure.

[0005] Figure 2(a) shows an example of a cut edge in the interior corner of a car body that cannot be reached by the measuring device due to interference between the measuring device and the object being measured, and Figure 2(b) is a partial enlarged schematic diagram. Since optical measuring devices with grayscale functions have strict angle requirements for sheet metal cut edge measurement, optical measuring devices without grayscale functions cannot accurately measure the cut edge size, so current optical measuring devices cannot measure such features efficiently and accurately.

[0006] Currently in the industry, there are two main methods for optical measurement equipment to solve the problem of cutting edge size detection in optical measurement.

[0007] The first method is to use a photographic optical measuring device to obtain the trimming size information using the principle of pixel grayscale difference. It is necessary to take a photo at a specific angle in the trimming space.

[0008] FIG4(a) illustrates the measurement angle required by traditional camera equipment. The shooting angle is as shown by the arrow. Only in this way can the schematic diagram of the trimming size of the pixel grayscale difference shown in FIG4(b) be obtained, and then the trimming size information is extracted using the grayscale principle.

[0009] It is easy to understand that there are two main shortcomings of this measurement method:

[0010] First, there are special requirements for the shooting angle during inspection. For certain corner features inside the car, the measurement head and arm interfere with the car body and cannot be measured. As a result, the scene shown in Figure 2 cannot be realized at all.

[0011] Second, for multi-layer sheet metal stacking, the pixel grayscale difference is unclear, unmeasurable or the measurement accuracy decreases.

[0012] Another method is that for scanning equipment without grayscale function, the sheet metal is too thin, and it is impossible to obtain high-precision point cloud for trimming and fitting while meeting the measurement cycle requirements, resulting in the inability to guarantee shooting accuracy or the possibility of failure to measure, such as Figure 5 shown. Summary of the invention

[0013] Based on the above-mentioned defects of sheet metal measurement and on-site requirements, there is an urgent need for an auxiliary measurement device and method that is not limited by the measurement scene and sheet metal stacking.

[0014] It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the disclosure.

[0015] The present invention cleverly utilizes the principle that there is a unique corresponding relationship between the cylindrical surface and the cylindrical axis of the auxiliary measuring device to coincide the cut edge of the sheet metal with the cylindrical axis, thereby converting the cut edge measurement into cylindrical axis measurement, i.e., cylindrical surface measurement. The data acquisition of the cylindrical surface is not restricted by angles in optical detection, so that measurement can be completed at multiple angles. The cylindrical surface is then fitted with the cylindrical axis in the software, thereby resolving the problem of unreachable blind spots in the vehicle body and improving the accuracy and efficiency of cut edge detection.

[0016] In order to achieve the above-mentioned object of the invention, the present invention provides a sheet metal trimming auxiliary measurement device, characterized in that the measurement device comprises:

[0017] The measuring body comprises a cylinder with an opening, wherein the opening is formed by enclosing a region from the axis of the cylinder to the circumference, thereby forming two measuring surfaces in the longitudinal section of the cylinder;

[0018] At least one magnetic strip is arranged in the measuring body near one of the two measuring surfaces along the axis direction of the cylinder;

[0019] The cross section of the measuring body is in a first sector shape, the cross section of the opening is in a second sector shape, the sum of the central angles of the first and second sectors is 360°, and the central angle of the first sector is greater than 180°.

[0020] Preferably, the present invention further provides a sheet metal trimming auxiliary measuring device, characterized in that the measuring device further comprises:

[0021] The measuring groove is arranged on the axis of the measuring body, and the two ends of the measuring groove do not penetrate the two end surfaces of the measuring body.

[0022] Preferably, the present invention further provides a sheet metal trimming auxiliary measuring device, characterized in that the measuring device further comprises:

[0023] The second magnetic strip is arranged in the measuring body near the other of the two measuring surfaces along the axial direction of the cylinder.

[0024] Preferably, the present invention further provides a sheet metal trimming auxiliary measurement device, characterized in that the central angle of the first sector includes either 240° or 270°.

[0025] Preferably, the present invention further provides a sheet metal trimming auxiliary measurement device, characterized in that the depth of the measuring groove is less than or equal to 3 mm.

[0026] The present invention also discloses a measurement method, which uses the aforementioned sheet metal trimming auxiliary measurement device, and is characterized in that the method comprises:

[0027] Step 1: adsorb the auxiliary measuring device on the trimming measuring point of the sheet metal and cover the measuring point;

[0028] Step 2, obtaining cylindrical point cloud information of the auxiliary measurement device;

[0029] Step 3, performing Gaussian optimal fitting on the cylindrical point cloud information to form the cylindrical axis, and the cylindrical axis corresponds to the trimming edge of the sheet metal;

[0030] Step 4: Use the intersection point of the theoretical section and the cylindrical axis generated by fitting to compare with the intersection point of the theoretical axis and the theoretical section, and judge whether it is qualified based on whether the coordinate difference between the two falls within the tolerance range.

[0031] Preferably, the present invention further provides a measurement method, characterized in that:

[0032] The coordinate difference in step 4 corresponds to the deviation between the theoretical measurement point and the actual trimming position.

[0033] Preferably, the present invention further provides a measurement method, characterized in that:

[0034] In the step 3, the fitting process uses GOM software from the German GOM company.

[0035] The present invention ingeniously converts the sheet metal cutting edges that are difficult to detect into cylindrical surface measurements, which reduces the shooting and scanning time and improves the measurement efficiency. At the same time, many previously inaccessible corner features are now accessible, which improves the detection accuracy and accessibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present disclosure, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals will be used in all drawings to represent the same or similar parts. In addition, although the terms used in the present disclosure are selected from well-known and commonly used terms, some of the terms mentioned in the present disclosure may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description herein. In addition, it is required to understand the present disclosure not only by the actual terms used, but also by the meaning implied by each term.

[0037] The above and other objects, features and advantages of the present invention will become apparent to those skilled in the art from the detailed description of the present invention with reference to the accompanying drawings below.

[0038] FIG. 1( a ) is an example diagram of a multi-layer sheet metal stack on a conventional vehicle body;

[0039] FIG1( b ) is a partial enlarged schematic diagram of FIG1( a );

[0040] FIG2( a ) is a schematic diagram showing an example of a corner of a conventional vehicle body;

[0041] FIG2( b ) is a partial enlarged schematic diagram of FIG2( a );

[0042] Figure 3 A measurement schematic diagram of the sheet metal trimming auxiliary measurement device of the present invention is given;

[0043] FIG4( a ) is a schematic diagram of the measurement angle of a conventional camera-type device;

[0044] FIG4( b ) is a schematic diagram of the edge cutting of the pixel grayscale difference in the manner of FIG4( a );

[0045] Figure 5 This is a schematic diagram obtained by traditional optical measurement on thin sheet metal;

[0046] FIG6( a ) is a perspective view of the sheet metal trimming auxiliary measurement device of the present invention;

[0047] FIG6( b ) is a front view of the sheet metal trimming auxiliary measurement device of the present invention;

[0048] FIG6( c ) is a BB cross-sectional view of FIG6( b );

[0049] FIG6( d ) is a CC cross-sectional view of FIG6( c );

[0050] Fig. 6(e) is a right side view of Fig. 6(b);

[0051] FIG6( f ) is a cross-sectional view taken along line AA of FIG6( e );

[0052] Figure 7 A measurement schematic diagram of the sheet metal trimming auxiliary measurement device of the present invention is illustrated;

[0053] Figure 8(a) is a schematic diagram of the position deviation of the two-dimensional cross section between the theoretical measuring point P and the actual measuring point P0;

[0054] FIG8(b) is a schematic diagram of the three-dimensional position deviation between the theoretical measuring point P and the actual measuring point P0 when the device of the present invention is used;

[0055] Fig. 9 A schematic diagram of a cylindrical point cloud obtained in a preferred embodiment is shown;

[0056] Fig.10 is based on Fig. 9 Schematic diagram of cylindrical point cloud after fitting;

[0057] Fig.11 Schematic diagram of the three-dimensional position deviation between the theoretical measuring point P and the actual measuring point P0.

[0058] Reference numerals

[0059] 10 - Measurement subject

[0060] 11 - Measuring slot

[0061] 12 - First measuring surface

[0062] 13 - Second measuring surface

[0063] 14 - First magnetic stripe

[0064] 15 - Second magnetic stripe

[0065] 100 - Auxiliary measuring device

[0066] 200 - Sheet Metal DETAILED DESCRIPTION

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0068] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0069] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0070] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0071] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0072] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0073] Figure 3 A schematic diagram of the sheet metal trimming auxiliary measuring device of the present invention in the measuring state is given. Specifically, the auxiliary measuring device 100 is clamped on the trimming of the sheet metal 200. The measuring device and the measuring process will be described in detail later.

[0074] See also Figure 6(a) to 6(f) , the structure of the sheet metal trimming auxiliary measurement device of the present invention is given.

[0075] Among them, Figure 6(a) is a three-dimensional view of the sheet metal trimming auxiliary measurement device, Figure 6(b) is its front view, Figure 6(c) is the BB cross-sectional view of Figure 6(b), Figure 6(d) is the CC cross-sectional view of Figure 6(c), Figure 6(e) is the right view of Figure 6(b), and Figure 6(f) is the AA cross-sectional view of Figure 6(e).

[0076] The sheet metal trimming auxiliary measurement device includes a measuring body, an opening portion on the cylinder, the opening portion is formed by enclosing the area from the axis of the cylinder to the circumferential surface, the cross-section of the opening portion is fan-shaped, and two measuring surfaces are formed in the longitudinal section of the cylinder, and at least one magnetic strip is arranged in the measuring body close to the measuring surface along the axis of the cylinder.

[0077] The cross section of the measuring body is a first sector shape, and the cross section of the opening is a second sector shape, which are combined into a circular cross section of a cylinder. The central angle of the first sector is greater than 180°, so the measuring body is a cylinder greater than 1 / 2.

[0078] In a preferred embodiment, the measuring body is a 2 / 3 or 3 / 4 cylinder.

[0079] A long strip measuring groove 11 is provided inwardly from the axis of the measuring body 10. The two ends of the measuring groove 11 do not have end surfaces that penetrate the measuring body 10. That is, the measuring groove 11 is only provided between the two end surfaces of the cylinder. Figure 6(b) , 6(d) The structure can be clearly seen in FIG6( f ).

[0080] In a preferred embodiment, the depth of the measuring groove 11 is less than or equal to 3 mm, in order to prevent welding slag from falling into it and affecting the measurement.

[0081] In the figure, the measuring body 10 includes two measuring surfaces, which correspond to the first and second measuring surfaces 12 and 13 formed between the axis and the cylindrical surface of the cylinder after removing the opening portion.

[0082] A first magnetic strip 14 is embedded in the measuring body 10 , parallel to the axis of the cylinder or the measuring slot 11 , and close to the first measuring surface 12 .

[0083] In a preferred embodiment, for the convenience of measurement, a second magnetic strip 15 is usually provided on the measuring body 10 , which is also parallel to the axis of the cylinder or the measuring slot 11 and close to the second measuring surface 13 .

[0084] Figure 7 The measurement schematic diagram of the sheet metal trimming auxiliary measurement device of the present invention is shown, and the whole measurement process is introduced in conjunction with the diagram:

[0085] Step 1, providing a measurement plan including a theoretical axis and a theoretical cross section;

[0086] Step 2: The measurement personnel adsorb the auxiliary measurement device 100 at the trimming measurement point of the sheet metal, and ensure that the measurement body 10 covers the measurement point P0. The measurement point P0 is the designated detection position specified in the measurement plan. The position is determined by the measurement personnel after comparing with the measurement plan. At this time, the measurement point P0 just falls on the measured cylindrical axis of the measurement body 10.

[0087] Step 3: Use optical measuring equipment to obtain the cylindrical point cloud information of the auxiliary measuring device 100 of the present invention, that is, the digital point cloud of the real cylindrical surface. This inventive method is not limited to photographic or scanning optical equipment, and any equipment that can obtain the surface point cloud of the measured object can be used. Fig. 9Shown is the acquired cylindrical point cloud.

[0088] Due to the use of the specially designed measuring device provided by the present invention, in this step, the acquisition of cylindrical surface data is not subject to angle restrictions in optical detection, that is, shooting or scanning is not subject to any angle restrictions, so it can be performed at multiple angles, and only one photo is needed at any angle. Therefore, the problem that the traditional method requires two to three photos to shoot a cut edge and the shooting is restricted is fundamentally solved.

[0089] Step 4: Use the acquired cylindrical point cloud information to perform Gaussian optimal fitting, complete the cylindrical construction, and generate the only axis of the fitted cylinder, which is considered to be the edge of the sheet metal trimming;

[0090] In a preferred embodiment, the processing method used for fitting can be implemented in current mainstream software, aiming to find the actual cylinder axis.

[0091] Fig.10 As shown, the GOM software of the German GOM company used in the preferred embodiment obtains the complete cylinder and its axis.

[0092] Step 5: According to the theoretical section provided in step 1, the theoretical section is used to obtain the only intersection point P0 with the cylindrical axis generated by fitting in step 4, where P is the intersection point of the theoretical axis and the theoretical section in the measurement scheme, as shown in FIG8(b);

[0093] Step 6. In the specified coordinate system, evaluate the position deviation (X0-X, Y0-Y, Z0-Z) between the theoretical measuring point P (X, Y, Z) and the actual measuring point P0 (X0, Y0, Z0), that is, the actual trimming position, and complete the trimming dimension measurement, as shown in Figure 8(a); and evaluate whether it is qualified based on whether the theoretical measuring point and the actual measuring point fall within the tolerance range.

[0094] The present invention cleverly converts the difficult-to-detect sheet metal cutting edges into cylindrical surface measurements, and is particularly suitable for use in the field of optical size detection. Compared with the original direct detection of sheet metal cutting edges, whether it is the grayscale principle or the point cloud fitting principle, it reduces the shooting and scanning time, improves the measurement efficiency, and at the same time, many previously inaccessible corner features are now accessible, improving the detection accuracy and accessibility.

[0095] The basic concepts have been described above. Obviously, for those skilled in the art, the above invention disclosure is only used as an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0096] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0097] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0098] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0099] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A measuring method, applied to a sheet metal trimming auxiliary measuring device, the measuring device comprising: The measuring body comprises a cylinder with an opening, wherein the opening is formed by enclosing a region from the axis of the cylinder to the circumference, thereby forming two measuring surfaces in the longitudinal section of the cylinder; At least one magnetic strip is arranged in the measuring body near one of the two measuring surfaces along the axis direction of the cylinder; The cross section of the measuring body is in a first sector shape, the cross section of the opening is in a second sector shape, the sum of the central angles of the first and second sectors is 360°, and the central angle of the first sector is greater than 180°; Characterized in that the measuring method comprises: Step 1: adsorb the auxiliary measuring device on the trimming measuring point of the sheet metal and cover the measuring point; Step 2, obtaining cylindrical point cloud information of the auxiliary measurement device; Step 3, performing Gaussian optimal fitting on the cylindrical point cloud information to form the cylindrical axis, and the cylindrical axis corresponds to the trimming edge of the sheet metal; Step 4: Use the intersection point of the theoretical section and the cylindrical axis generated by fitting to compare with the intersection point of the theoretical axis and the theoretical section, and judge whether it is qualified based on whether the coordinate difference between the two falls within the tolerance range.

2. The measuring method according to claim 1, characterized in that: The measuring device further comprises: The measuring groove is arranged on the axis of the measuring body, and the two ends of the measuring groove do not penetrate the two end surfaces of the measuring body.

3. The measuring method according to claim 2, characterized in that: The measuring device further comprises: The second magnetic strip is arranged in the measuring body near the other of the two measuring surfaces along the axial direction of the cylinder.

4. The measuring method according to claim 3, characterized in that: The central angle of the first sector includes either 240° or 270°.

5. The measuring method according to claim 2, characterized in that: The depth of the measuring groove is less than or equal to 3 mm.

6. The measuring method according to claim 1, characterized in that: The coordinate difference in step 4 corresponds to the deviation between the theoretical measurement point and the actual trimming position.

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