Measuring tool for multi-bend pipe

Abstract

The utility model discloses a measuring tool for a multi-bend pipe, and relates to the technical field of pipeline measurement. The measuring tool for the multi-bend pipe comprises a first measuring plate which comprises a first surface; the first surface is provided with a first profiling groove; the second measuring plate comprises a second surface corresponding to the first measuring plate; the second surface is provided with a second profiling groove; the first profiling groove and the second profiling groove are spliced to form a profiling channel capable of containing a multi-bend pipe. The shape and position size of the inner wall of the profiling channel is similar to the shape and position size of the outer wall when the multi-bend pipe is designed. Through the arrangement of the first measuring plate with the first profiling groove and the second measuring plate with the second profiling groove, the shape and position dimension measurement of the multi-bend pipe is converted into the measurement of the plate gap. Compared with the shape and position dimension measurement of the multi-bend pipe, the measurement difficulty of the plate gap is low, the measurement period is short, the detection efficiency can be improved, and the detection cost can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of pipeline measurement, and in particular to a measuring tool for multi-bend pipes. Background Art

[0002] Tube parts with multiple bends at spatial angles (e.g. Figure 1 The shape and position dimensions of a multi-bend tube (as shown in the figure) are often expressed as spatial profiles. Detecting the shape and position dimensions of such tube parts after forming is generally difficult to achieve using conventional testing methods. For example, using conventional three-dimensional coordinate measurement methods, the tube's spatial angles necessitate precise measurement of the normal vectors of the measured points when measuring curved surfaces and spatial angles. Otherwise, during data processing, projection cosine errors can easily occur during probe radius compensation, increasing measurement difficulty and test cycle time, reducing test efficiency, and increasing testing costs. Utility Model Content

[0003] The purpose of this application is to provide a measuring tool for multi-bend pipes to solve the technical problems of difficulty in measuring the shape and size of multi-bend pipes and long measurement cycle.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] A measuring tool for a multi-bend pipe comprises: a first measuring plate including a first surface; a first profiling groove provided on the first surface; a second measuring plate including a second surface corresponding to the first measuring plate; a second profiling groove provided on the second surface; after the second measuring plate is engaged with the first measuring plate based on the first surface and the second surface, the first profiling groove and the second profiling groove are joined to form a profiling channel capable of accommodating the multi-bend pipe; the shape and position dimensions of the inner wall of the profiling channel are similar to the shape and position dimensions of the outer wall of the multi-bend pipe when it is designed.

[0006] As a specific solution in the technical solution of the present application, the first surface and / or the second surface is provided with distance measuring grooves corresponding one-to-one to the end faces of the multi-bend tube.

[0007] As a specific solution in the technical solution of this application, the ranging groove includes a first measuring end face and a second measuring end face; the first measuring end face and the second measuring end face are both parallel to the corresponding end face of the multi-bend tube; the distance between the first measuring end face and the second measuring end face is equal to the dimensional tolerance of the axial length of the corresponding end face of the multi-bend tube.

[0008] As a specific solution in the technical solution of the present application, the first surface is provided with ranging grooves corresponding one-to-one to the end faces of the multi-bend tube; the first measuring plate is provided with movable blocks corresponding one-to-one to the ranging grooves; each movable block is detachably connected to the first measuring plate; and the ranging grooves are provided on the corresponding movable blocks; or, the second surface is provided with ranging grooves corresponding one-to-one to the end faces of the multi-bend tube; the second measuring plate is provided with movable blocks corresponding one-to-one to the ranging grooves; each movable block is detachably connected to the first measuring plate; and the ranging grooves are provided on the corresponding movable blocks.

[0009] As a specific solution in the technical solution of the present application, the outer diameter of the movable block increases gradually along a first direction; the first direction is parallel to the fastening direction of the first measuring plate and the second measuring plate.

[0010] As a specific solution in the technical solution of the present application, the movable block is in the shape of a quadrangular pyramid or a truncated pyramid.

[0011] As a specific solution in the technical solution of the present application, the movable block is provided with at least one notch for accommodating a human finger, and each notch is provided with an anti-slip groove.

[0012] As a specific solution in the technical solution of the present application, the shape and position dimensions of the inner wall of the contoured channel are equal to the shape and position dimensions of the outer wall when the multi-bend tube is designed.

[0013] As a specific solution in the technical solution of the present application, the first measuring plate and / or the second measuring plate is provided with at least one lifting handle.

[0014] As a specific solution in the technical solution of this application, the first surface is provided with at least one positioning hole, and the second surface is provided with positioning columns corresponding one-to-one to the positioning holes; or, the second surface is provided with at least one positioning hole, and the first surface is provided with positioning columns corresponding one-to-one to the positioning holes.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] This application utilizes a first measuring plate with a first contoured groove and a second measuring plate with a second contoured groove to convert the form and position dimensional measurement of multi-bend tubes into plate gap measurement. Compared to the form and position dimensional measurement of multi-bend tubes, plate gap measurement is less challenging and has a shorter measurement cycle, improving inspection efficiency and reducing inspection costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A three-dimensional schematic diagram of a multi-bend tube proposed in an embodiment of the present application;

[0018] Figure 2A three-dimensional schematic diagram of a measuring tool proposed in an embodiment of the present application;

[0019] Figure 3 A schematic top view of a second measurement plate proposed in an embodiment of the present application (with a multi-bend tube placed);

[0020] Figure 4 for Figure 3 Enlarged view of part A;

[0021] Figure 5 A schematic front view of a first measurement plate proposed in an embodiment of the present application;

[0022] Figure 6 A schematic top view of another second measurement plate proposed in an embodiment of the present application (without the multi-bend tube);

[0023] Figure 7 A three-dimensional schematic diagram of a movable block proposed in an embodiment of the present application;

[0024] Figure 8 This is a three-dimensional schematic diagram of another movable block proposed in an embodiment of the present application.

[0025] In the figure: 1. Multi-bend tube; 11. First straight tube; 12. First bending portion; 13. Second straight tube; 14. Second bending portion; 15. Third straight tube; 16. Third bending portion; 17. Fourth straight tube; 18. First end face; 19. Second end face; 2. First measuring plate; 21. Positioning column; 3. Second measuring plate; 31. Positioning hole; 32. Distance measuring groove; 321. First measuring end face; 322. Second measuring end face; 33. Movable block; 34. Notch; 341. Anti-slip groove; 4. Profiling channel; 41. Second profiling groove; 42. First profiling groove; 5. Plate gap; 6. Lifting handle. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] It should be noted that, in the description of this application, the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation on this application.

[0028] Furthermore, it should be understood that for the sake of ease of description, the sizes of the various components shown in the drawings are not drawn according to actual proportions. For example, the thickness or width of certain layers may be exaggerated relative to other layers.

[0029] It should be noted that like numbers and letters represent similar items in the following figures, so once an item is defined or described in one figure, it will not need to be further discussed and described in detail in the description of the subsequent figures.

[0030] Before understanding the embodiments proposed in this application, this application is based on the following Figure 1 The multi-bend tube shown in the figure is used as an example to explain in detail why it is difficult to measure the shape and position dimensions of a multi-bend tube with a spatial angle. Figure 1 As shown, the multi-bend tube 1 is formed by sequentially connecting a first straight tube 11, a first bend portion 12, a second straight tube 13, a second bend portion 14, a third straight tube 15, a third bend portion 16 and a fourth straight tube 17. It is easy to understand that since the axis center lines of the first straight tube 11 and the second straight tube 13, the axis center lines of the second straight tube 13 and the third straight tube 15, and the axis center lines of the third straight tube 15 and the fourth straight tube 17 are coplanar, it is easy to detect whether the angle formed between the first straight tube 11 and the second straight tube 13, the angle formed between the second straight tube 13 and the third straight tube 15, and the angle formed between the third straight tube 15 and the fourth straight tube 17 are qualified. Figure 1 It can be seen that the axis lines of the first straight tube 11 and the third straight tube 15 are not in the same plane, the axis lines of the first straight tube 11 and the fourth straight tube 17 are not in the same plane, and the axis lines of the second straight tube 13 and the fourth straight tube 17 are not in the same plane. Therefore, it is difficult to detect whether the angle between the first straight tube 11 and the third straight tube 15, the angle between the first straight tube 11 and the fourth straight tube 17, and the angle between the second straight tube 13 and the fourth straight tube 17 are qualified. In other words, since there are multiple straight tubes whose axis lines are not in the same plane, it is difficult to detect whether the angle between the first straight tube 11 and the third straight tube 15, the angle between the first straight tube 11 and the fourth straight tube 17, and the angle between the second straight tube 13 and the fourth straight tube 17 are qualified. Figure 1 Whether the shape and position dimensions of the multi-bend tube 1 shown are qualified. It is easy to understand that if there are two straight tube parts with axial center lines that are not in the same plane as each other in the multi-bend tube, the shape and position dimensions of the multi-bend tube are difficult to measure.

[0031] Please note that this application is only Figure 1The multi-bend tube 1 shown in the figure is used to illustrate the embodiment of the measuring tool proposed in this application. It does not mean that the measuring tool proposed in this application can only be used in Figure 1 The multi-bend tube 1 shown is measured for shape and position. It should be understood that the measurement tool proposed in this application can be applied to measure the shape and position of any multi-bend tube. Any of the multi-bend tubes mentioned above includes multi-bend tubes with two straight tube sections whose axis lines are unequal, as well as multi-bend tubes with the axis lines of all straight tube sections being coplanar. Extensive examples are not provided here.

[0032] In order to solve the technical problems of the difficulty in measuring the shape and position of multi-bend pipes and the long measurement cycle in the prior art, the present application proposes a multi-bend pipe measuring tool, which includes a first measuring plate 2 and a second measuring plate 3. Figure 5 As shown, the first measuring plate 2 comprises a first surface, and the first surface is provided with a first contoured groove 42. Figure 3 and Figure 6 As shown, the second measuring plate 3 includes a second surface corresponding to the first measuring plate 2, and the second surface is provided with a second contoured groove 41. Figure 2 As shown, after the second measuring plate 3 and the first measuring plate 2 are fastened together based on the first and second surfaces, the first contoured groove 42 and the second contoured groove 41 are joined to form a contoured channel 4 capable of accommodating the multi-bend tube 1. The shape and dimensions of the inner wall of the contoured channel 4 are similar to those of the outer wall of the multi-bend tube 1 when it is designed.

[0033] When in use, first place the multi-bend tube 1 to be tested into the first profiling groove 42 or the second profiling groove 41. Figure 2 As shown, the first measuring plate 2 and the second measuring plate 3 are fastened together based on the first surface and the second surface. Figure 2 As shown, a plate gap 5 is formed between the first and second measurement plates 2 and 3 after they are fastened together. Because the inner wall dimensions of the contoured channel 4 formed by the first and second contoured grooves 42 and 41 are similar to the outer wall dimensions of the multi-bend tube 1 during design, qualified and unqualified multi-bend tubes 1 inevitably result in different plate gaps 5 formed after the first and second measurement plates 2 and 3 are fastened together. In other words, in this embodiment, the conformity of the multi-bend tube 1 under test can be determined based on the plate gap 5 formed after the first and second measurement plates 2 and 3 are fastened together.

[0034] It is easy to understand that in the embodiments of the present application, the size of the plate gap 5 can be manually estimated based on the naked eye to determine whether the shape and position dimensions of the multi-bend tube 1 to be tested are qualified; the size of the plate gap 5 can also be measured by measuring tools such as a feeler gauge or a caliper to determine whether the shape and position dimensions of the multi-bend tube 1 to be tested are qualified.

[0035] It is easy to understand that the embodiments of the present application, through the provision of a first measuring plate 2 having a first contoured groove 42 and a second measuring plate 3 having a second contoured groove 41, achieve the conversion of the form and position dimensional measurement of a multi-bend tube 1 into the measurement of the plate gap 5. Compared to the form and position dimensional measurement of a multi-bend tube 1, the measurement of the plate gap 5 is less difficult and has a shorter measurement cycle, thereby improving inspection efficiency and reducing inspection costs.

[0036] It should be understood that the shape and position dimensions of the inner wall of the profiling channel 4 are similar to the shape and position dimensions of the outer wall of the multi-bend tube 1 when it was designed. This means that the shape and position dimensions of the inner wall of the profiling channel 4 can be equal to the shape and position dimensions of the outer wall of the multi-bend tube 1 when it was designed. It is easy to understand that any product has tolerances during the production process. In order to avoid the inner wall of the profiling channel 4 being larger, when the size of the multi-bend tube 1 is at the minimum limit size, it is difficult to measure whether the shape and position dimensions of the multi-bend tube 1 at the minimum limit size are qualified using the above method. The shape and position dimensions of the inner wall of the profiling channel 4 can also be equal to the minimum limit size of the outer wall of the multi-bend tube 1 when it was designed based on the tolerance. Generally speaking, the shape and position dimensions of the inner wall of the profiling channel 4 are similar to the shape and position dimensions of the outer wall of the multi-bend tube 1 when it was designed.

[0037] In order to be able to test whether the length of the multi-bend tube 1 is qualified, in one embodiment of the present application, the second surface is provided with a distance measuring groove 32 corresponding to the end face of the multi-bend tube 1. The distance measuring groove 32 is used to indicate whether the axial length of the corresponding end face of the multi-bend tube 1 is qualified. It should be understood that the distance measuring groove 32 corresponds to the end face of the multi-bend tube 1 in a one-to-one manner, which means that the same number of distance measuring grooves 32 is provided as the number of end faces of the multi-bend tube 1 to be tested. For example, Figure 1 The multi-bend tube 1 shown has a first end face 18 and a second end face 19 (i.e., two end faces). Figure 3 and Figure 6 As shown, two distance measuring grooves 32 are provided on the second surface. If the multi-bend tube 1 is a tee tube, that is, the multi-bend tube 1 has three end surfaces, three distance measuring grooves 32 are provided on the second surface, and so on.

[0038] In an embodiment of the present application, the distance measuring groove 32 can be used to determine in any way whether the axial length of the corresponding end face of the multi-bend tube 1 is qualified. For example, a scale can be set on the distance measuring groove 32, and whether the length of the end face of the multi-bend tube 1 is qualified can be determined based on the scale. In order to be able to quickly determine whether the length of the end face of the multi-bend tube 1 is qualified, in one embodiment of the present application, the distance measuring groove 32 includes a first measuring end face 321 and a second measuring end face 322, and the first measuring end face 321 and the second measuring end face 322 are both parallel to the end face corresponding to the multi-bend tube 1, and the distance between the first measuring end face 321 and the second measuring end face 322 (that is, as shown in FIG. Figure 4 The distance d) shown is equal to the dimensional tolerance of the axial length of the corresponding end face of the multi-bend tube 1.

[0039] When using, Figure 3 As shown, the multi-bend tube 1 is placed into the second profiling groove 41. Since the distance between the first measuring end face 321 and the second measuring end face 322 is equal to the dimensional tolerance of the axial length of the corresponding end face of the multi-bend tube 1, after the multi-bend tube 1 is placed into the second profiling groove 41, if Figure 4 If the corresponding end face of the multi-bend tube 1 is located between the first measurement end face 321 and the second measurement end face 322, the length of the end face of the multi-bend tube 1 is qualified; otherwise, the length of the end face of the multi-bend tube 1 is unqualified. This method can quickly determine whether the end face length of the multi-bend tube 1 is qualified, saving time and effort.

[0040] It is easy to understand that in the embodiments of the present application, the distance measuring groove 32 can be provided only on the second surface. In other embodiments of the present application, the distance measuring groove 32 can be provided only on the first surface. To facilitate operator use, in some embodiments of the present application, the distance measuring groove 32 can be provided on both the first surface and the second surface. In other words, the operator can choose to place the multi-bend tube 1 to be tested into the first profiling groove 42 or the second profiling groove 41 according to user habits, and can quickly determine whether the end face length of the multi-bend tube 1 is qualified.

[0041] It should be understood that multi-bend tubes 1 of the same specification but different models differ only in the axial length of their end faces. To enable the use of the same measurement tool for measuring all multi-bend tubes 1 that differ only in their end face axial lengths, in one embodiment of the present application, the second measurement plate 3 is provided with movable blocks 33 corresponding one-to-one with the distance measuring grooves 32. Each movable block 33 is detachably connected to the first measurement plate 2, and the distance measuring groove 32 is provided on the corresponding movable block 33.

[0042] When using, Figure 6 As shown, since the movable block 33 is detachably connected to the second measuring plate 3, the same measuring tool can be used to measure multi-bend tubes 1 with different end face axial lengths by simply replacing a different movable block 33. In the embodiment of the present application, the movable block 33 can be detachably connected to the first measuring plate 2 in any manner, for example, the movable block 33 can be connected to the first measuring plate 2 by bolts; or Figure 6 As shown, the second surface of the second measurement plate 3 is arranged upward, and the movable block 33 falls into the second measurement plate 3 only due to gravity, thereby forming a detachable connection with the second measurement plate 3 .

[0043] It is easy to understand that in other embodiments of the present application, if the first surface is provided with a ranging groove 32 corresponding one-to-one to the end surface of the multi-bend tube 1, then the first measuring plate 2 can also be provided with a movable block 33 corresponding one-to-one to the ranging groove 32, and each movable block 33 is detachably connected to the first measuring plate 2, and the ranging groove 32 on the first surface is provided on the corresponding movable block 33 on the first surface.

[0044] In the embodiment of the present application, there is no restriction on the shape and structure of the movable block 33. In order to facilitate the disassembly of the movable block 33, the outer diameter of the movable block 33 along the first direction can be increased gradually. The first direction is parallel to the fastening direction of the first measuring plate 2 and the second measuring plate 3 (that is, as shown in FIG. Figure 7 and Figure 8 It is easy to understand that if the outer diameter of the movable block 33 increases along the first direction, it is easy to remove the movable block 33 from the second measuring plate 3. In the embodiment of the present application, the movable block 33 can be as follows: Figure 7 and Figure 8 The shown structure is a quadrangular pyramid, but the movable block 33 can also be a truncated pyramid structure.

[0045] In order to further facilitate the removal of the movable block 33 from the second measurement plate 3, in one embodiment of the present application, the movable block 33 is provided with at least one notch 34 for accommodating a human finger, and each notch 34 is provided with an anti-slip groove 341. When in use, the notch 34 can increase the friction between the movable block 33 and the human finger, thereby facilitating the operator to remove the movable block 33. In the embodiment of the present application, there is no limit to the number of notches 34, which can be one, two, three, or more. Figure 8 The four shown are etc.

[0046] In the embodiment of the present application, mechanical equipment can be used to fasten the first measuring plate 2 and the second measuring plate 3 together. For example, an electric push rod or a hydraulic push rod can be used to fasten the first measuring plate 2 and the second measuring plate 3 together. The first measuring plate 2 and the second measuring plate 3 can also be fastened together manually. In order to facilitate the manual separation of the first measuring plate 2 and the second measuring plate 3 after the test is completed, the first measuring plate 2 and the second measuring plate 3 can be fastened together manually. Figure 2 and Figure 5 As shown, at least one lifting handle 6 is provided on the first measurement plate 2. Of course, in other embodiments of the present application, the lifting handle 6 may be provided on the second measurement plate 3; or the lifting handle 6 may be provided on both the first measurement plate 2 and the second measurement plate 3.

[0047] In order to avoid the first measuring plate 2 and the second measuring plate 3 from shifting during the fastening process, thereby affecting the test results, in one embodiment of the present application, Figure 3 and Figure 6As shown, the first surface is provided with at least one positioning hole 31; Figure 5 As shown, the second surface is provided with positioning posts 21 corresponding one-to-one with positioning holes 31. The provision of positioning holes 31 and positioning posts 21 prevents displacement of the first measurement plate 2 and the second measurement plate 3 during the fastening process. It will be readily understood that in other embodiments of the present application, positioning holes 31 may be provided on the second surface, while positioning posts 21 may be provided on the first surface.

[0048] It should be noted that the embodiments of this application utilize a first measurement plate with a first contoured groove and a second measurement plate with a second contoured groove to convert the form and position dimensional measurement of multi-bend tubes into plate gap measurement. Compared to the form and position dimensional measurement of multi-bend tubes, plate gap measurement is less challenging and has a shorter measurement cycle, thus improving inspection efficiency and reducing inspection costs.

[0049] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A measuring tool for multi-bend pipes, characterized in that: include: A first measuring plate (2) comprising a first surface; the first surface is provided with a first contoured groove (42); The second measuring plate (3) comprises a second surface corresponding to the first measuring plate (2); the second surface is provided with a second profiling groove (41); after the second measuring plate (3) and the first measuring plate (2) are buckled together based on the first surface and the second surface, the first profiling groove (42) and the second profiling groove (41) are spliced ​​to form a profiling channel (4) capable of accommodating the multi-bend tube (1); the shape and position dimensions of the inner wall of the profiling channel (4) are similar to the shape and position dimensions of the outer wall of the multi-bend tube (1) when it is designed.

2. The multi-bend pipe measuring tool according to claim 1, characterized in that: The first surface and / or the second surface are provided with distance measuring grooves (32) corresponding one-to-one to the end faces of the multi-bend tube (1).

3. The measuring tool for multi-bend pipe according to claim 2, characterized in that: The distance measuring groove (32) comprises a first measuring end face (321) and a second measuring end face (322); the first measuring end face (321) and the second measuring end face (322) are both parallel to the end face corresponding to the multi-bend tube (1); and the distance between the first measuring end face (321) and the second measuring end face (322) is equal to the dimensional tolerance of the axial length of the end face corresponding to the multi-bend tube (1).

4. The multi-bend pipe measuring tool according to claim 3, characterized in that: The first surface is provided with distance measuring grooves (32) corresponding one-to-one to the end surface of the multi-bend tube (1); the first measuring plate (2) is provided with movable blocks (33) corresponding one-to-one to the distance measuring grooves (32); each movable block (33) is detachably connected to the first measuring plate (2); and the distance measuring grooves (32) are provided on corresponding movable blocks (33); Alternatively, the second surface is provided with distance measuring grooves (32) corresponding one-to-one to the end surface of the multi-bend tube (1); the second measuring plate (3) is provided with movable blocks (33) corresponding one-to-one to the distance measuring grooves (32); each movable block (33) is detachably connected to the first measuring plate (2); and the distance measuring grooves (32) are provided on the corresponding movable blocks (33).

5. The multi-bend pipe measuring tool according to claim 4, characterized in that: The outer diameter of the movable block (33) increases gradually along a first direction; the first direction is parallel to the fastening direction of the first measuring plate (2) and the second measuring plate (3).

6. The multi-bend pipe measuring tool according to claim 5, characterized in that: The movable block (33) is in the shape of a quadrangular pyramid or a truncated pyramid.

7. The multi-bend pipe measuring tool according to claim 5, characterized in that: The movable block (33) is provided with at least one notch (34) for accommodating a human finger, and each notch (34) is provided with an anti-slip groove (341).

8. The multi-bend pipe measuring tool according to any one of claims 1 to 7, characterized in that: The shape and position dimensions of the inner wall of the contoured channel (4) are equal to the shape and position dimensions of the outer wall of the multi-bend tube (1) when it is designed.

9. The multi-bend pipe measuring tool according to any one of claims 1 to 7, characterized in that: The first measuring plate (2) and / or the second measuring plate (3) are provided with at least one lifting handle (6).

10. The multi-bend pipe measuring tool according to any one of claims 1 to 7, characterized in that: The first surface is provided with at least one positioning hole (31), and the second surface is provided with positioning posts (21) corresponding one-to-one to the positioning holes (31); Alternatively, the second surface is provided with at least one positioning hole (31), and the first surface is provided with positioning posts (21) corresponding one-to-one to the positioning holes (31).

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