Long product positioning and measuring equipment

Abstract

The utility model discloses long product positioning measuring equipment, which relates to the field of measuring equipment, and adopts the technical scheme that the long product positioning measuring equipment comprises a base platform and a long-strip-shaped base platform bedplate; the supporting unit is fixedly arranged on the upper side of the base table, the supporting unit is fixedly connected with the base table, and the supporting unit can support a product to be detected; the positioning unit is arranged on the base table, and the positioning unit can fix the bottom or / and the side part of the product; the fixed detection unit is fixedly arranged on the base table, and the fixed detection unit can detect the vertical appearance structure of the product; and the movable detection unit is connected with the base table in a sliding manner, and the movable detection unit can detect the structure of the product in the horizontal direction. The beneficial effects of the utility model are that the detection device can detect long products, and through combination of the supporting unit, the fixed detection unit and the movable detection unit of the products, various appearance structures of the products can be rapidly and visually measured.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of measuring equipment, concretely to a long product positioning measuring equipment. BACKGROUND

[0002] In the automobile manufacturing process, there are long products, such as electric vehicle battery fixing plate baffles, which need to consider various design elements, such as mounting holes, mounting shafts, protrusions and rib structures corresponding to the battery parts, etc. The consistency of the product needs to be ensured, and at the same time, different design sizes need to meet the requirements. For such products with relatively long length and many detection contents, the work intensity is quite high.

[0003] Therefore, how to reduce the detection difficulty of such long products is the problem to be solved by the present application. UTILITY MODEL CONTENT

[0004] In view of one of the deficiencies of the prior art, the utility model provides a long product positioning measuring equipment to solve the detection problem of long products.

[0005] To achieve the above purpose, the utility model provides the following technical scheme: a long product positioning measuring equipment, comprising:

[0006] The base station comprises a long strip-shaped base station plate;

[0007] The support unit is fixedly arranged on the upper side of the base station, and the support unit and the base station are fixedly connected. The support unit can support the product to be detected;

[0008] The positioning unit is arranged on the base station. The positioning unit can fix the bottom or side of the product;

[0009] The fixed detection unit is fixedly arranged on the base station. The fixed detection unit is arranged on the side of the support unit. The fixed detection unit can detect the vertical outer shape structure of the product;

[0010] The movable detection unit is slidably connected with the base station. The sliding direction is the length direction of the product. The movable detection unit can detect the structure in the horizontal direction of the product.

[0011] Preferably, the support unit comprises:

[0012] The bottom support member is a long strip-shaped structure. The bottom support member is vertically arranged on the upper surface of the base station. The bottom support member can be attached to the bottom surface of the product;

[0013] The side support member is arranged at both ends of the length direction of the bottom support member. The side support member is provided with a notch corresponding to the side of the product.

[0014] Preferably, the bottom support comprises:

[0015] a bottom boss, at least two of which are arranged on the upper side of the bottom support, vertically upwardly extending, the upper end face of the bottom boss abutting the bottom face of the product;

[0016] a bottom pillar, at least one of which is fixedly arranged on the upper end face of the bottom support, the upper end face of the bottom pillar abutting the bottom face of the product.

[0017] Preferably, the positioning unit comprises:

[0018] a bottom positioning assembly arranged on one side of the bottom support, capable of exerting a clamping force from top to bottom on the lower part of the product;

[0019] a side positioning assembly arranged on the horizontal side of the side support, capable of exerting a clamping force in the horizontal direction on the side end of the product.

[0020] Preferably, the bottom positioning assembly comprises:

[0021] a bottom positioning frame fixedly connected with the base;

[0022] a bottom pressing member vertically slidingly connected with the bottom positioning frame;

[0023] a bottom spring arranged between the bottom positioning frame and the bottom pressing member.

[0024] Preferably, the side positioning assembly comprises:

[0025] a side positioning frame fixedly connected with the base;

[0026] a side pressing member hingedly connected with the side positioning frame, the side pressing member extending towards the side end of the product.

[0027] Preferably, the fixed detection unit comprises:

[0028] a positioning pin detection assembly capable of detecting the positioning hole on the product;

[0029] a vertical face detection assembly capable of detecting the upper end face and the lower end face of the corresponding structure on the product.

[0030] Preferably, the positioning pin detection assembly comprises:

[0031] a positioning pin detection platform fixedly arranged on the base, the positioning pin detection platform being provided with a plug hole corresponding to the positioning hole of the product;

[0032] a positioning pin detection column capable of being plugged into the plug hole on the positioning pin detection platform;

[0033] the vertical face detection assembly comprises:

[0034] The vertical surface detection table is a vertical boss, and a notch is arranged on the vertical detection table and corresponds to the vertical surface structure of the product to be detected.

[0035] Preferably, the activity detection unit comprises:

[0036] The slide rail is fixedly connected with the base, and the length direction of the slide rail is parallel to the length direction of the product.

[0037] The movable detection frame is slidably connected with the slide rail, and the movable detection frame can slide along the slide rail.

[0038] The first detection piece is slidably connected with the movable detection frame, and the first detection piece can detect the rib position in the horizontal direction of the product.

[0039] The second detection piece is movably connected with the movable detection frame, and the second detection piece is a dial indicator.

[0040] Preferably, the activity detection unit further comprises:

[0041] The fixing structure is arranged corresponding to the slide rail and the movable detection frame, and the movable detection frame can be fixed on the slide rail through the fixing structure.

[0042] Compared with the prior art, the detection equipment has the following beneficial effects: the detection equipment can detect long products, and through the combination of the product supporting unit, the fixed detection unit and the movable detection unit, the various external structures of the product can be quickly and intuitively measured.

[0043] The positioning unit can well position the product, and the product to be detected can be quickly and conveniently installed and replaced. On the basis of the positioning unit, the fixed detection unit is combined, especially the positioning pin detection assembly, which can detect the corresponding structure of the product on one hand and can also position the product differently from the positioning unit on the other hand.

[0044] The movable activity detection unit can quickly detect the multiple protrusions and rib positions on the product, which can greatly save manpower and time. DETAILED DESCRIPTION

[0045] Figure 1 It is a schematic view of the long product to be detected in the embodiment of the application;

[0046] Figure 2 It is a schematic view of the overall structure of the embodiment of the application Figure 1 ;

[0047] Figure 3 It is a schematic view of the overall structure of the embodiment of the application Figure 2 ;

[0048] Figure 4 is a partial enlarged view of A of Figure 2

[0049] Figure 5 is a partial enlarged view of A of Figure 3

[0050] Figure 6 is a partial enlarged view of B of Figure 3

[0051] Figure 7 is a schematic diagram of the overall structure of the embodiment of the present application Figure 3

[0052] Figure 8 is a schematic diagram of the overall structure of the embodiment of the present application Figure 7

[0053] Figure 9 is a partial enlarged view of A of Figure 8

[0054] In the figure:

[0055] 100, product; 101, muscle position; 102, protruding block

[0056] 1, base station

[0057] 2, support unit; 21, bottom support piece; 211, bottom protruding block; 212, bottom support column; 22, side support piece

[0058] 3, positioning unit; 31, bottom positioning assembly; 311, bottom positioning frame; 312, bottom pressing piece; 313, bottom spring; 314, operating rod; 32, side positioning assembly; 321, side positioning frame; 322, side pressing piece

[0059] 4, fixed detection unit; 41, positioning pin detection assembly; 411, positioning pin detection table; 412, positioning pin detection column; 42, vertical surface detection assembly; 421, vertical surface detection table

[0060] 5, movable detection unit; 51, sliding rail; 52, movable detection frame; 53, positioning rod; 54, first positioning piece; 55, positioning table; 56, second positioning piece DETAILED DESCRIPTION

[0061] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. ​​​​​​

[0062] Please refer to Figures 1-9 , wherein Figure 1 The present application provides the following technical solutions for the product 100 to be detected in the present scheme:

[0063] A long product positioning and measuring device comprises a base 1, which can be of any shape, as long as it has a long base plate on the upper part. A support unit 2 is fixedly arranged on the upper side of the base 1, and the support unit 2 is fixedly connected with the base 1, and is used for supporting the product 100 to be detected. A positioning unit 3 is fixedly arranged on the base 1, and is used for fixing the bottom or side of the product 100 supported by the support unit 2. For the detection of the product 100, the present scheme is provided with a fixed detection unit 4 and a movable detection unit 5. The fixed detection unit 4 is fixedly connected with the base 1, and is arranged on the side of the support unit 2, and can detect the vertical outer shape structure of the product 100. The movable detection unit 5 is slidably connected with the base 1, and the sliding direction is the length direction of the product 100, and the movable detection unit 5 can detect the structure in the horizontal direction of the product.

[0064] For convenience of description, the state of the product 100 placed on the support unit 2 in the drawings is taken as the reference, and the vertical outer shape structure referred to by the fixed detection unit 4 in the present scheme mainly refers to the structure extending towards the horizontal two sides of the product 100, such as the plate structure extending in the horizontal direction of the product 100 shown in Figure 2 and Figure 5 . The fixed detection unit 4 mainly detects the upper side and lower side positions of the plate body of such structure. The movable detection unit 5 mainly detects the protruding block 102 shown in Figure 6 and the rib position 101 shown in Figure 4 , and the detection directions of the two are horizontal directions. Figure 6

[0065] On the basis of the above-mentioned embodiments, the support unit 2 comprises a bottom support member 21 which is in the shape of a whole long strip, and is vertically arranged on the upper surface of the base 1, and can be attached to the bottom surface of the product 100. Referring to Figure 4 and Figure 9 ​The long strip structure of the bottom support 21 is provided with a bottom boss 211 and a bottom support column 212 on the upper side. In this embodiment, two bottom bosses 211 are provided on the upper side of the bottom support 21, and the number can be changed according to the actual situation. The upper end surface of the bottom boss 211 is a horizontal surface. The two bottom bosses 211 vertically extend upwards, and the upper end surface is slightly higher than the position of the periphery. The upper end surface of the bottom boss 211 abuts against the bottom surface of the product 100. A plurality of bottom support columns 212 are arranged between the two bottom bosses 211, and the upper end surface of the bottom support column 212 abuts against the bottom surface of the product 100. Through this structure, the bottom boss 211 and the bottom support column 212 serve as the support body of the bottom surface of the product 100. A gap is formed between the area of the bottom support 21 other than the bottom boss 211 and the bottom support column 212 and the bottom surface of the product 100. The gap can be detected by means of a feeler gauge to confirm whether the shape of the bottom surface of the product 100 meets the requirements.

[0066] A side support 22 is arranged at each end of the length direction of the bottom support 21. The side support 22 is provided with a notch corresponding to the side edge of the product 100. The notch of the side support 22 is a semi-open structure, which can form a semi-enclosed structure for the side end of the product 100, facilitating the placement of the product 100.

[0067] On the basis of the above-mentioned embodiments, the bottom support 21 and the side support 22 of the support unit 2 are combined, and the positioning unit 3 is provided with a bottom positioning assembly 31 and a side positioning assembly 32. The bottom positioning assembly 31 is arranged on one side of the bottom support 21 and can exert a clamping force from top to bottom on the lower part of the product 100. Figure 4 The bottom positioning assembly 31 includes a bottom positioning frame 311 fixedly connected to the base 1, which is approximately in the shape of a "door". A bottom pressing member 312 is vertically and slidingly connected to the upper part of the bottom positioning frame 311, and the bottom pressing member 312 is in the form of a plate body extending towards the product 100. A bottom spring 313 is arranged between the bottom pressing member 312 and the bottom positioning frame 311. When installing the product 100, the bottom pressing member 312 is slightly pulled upwards, and the bottom spring 313 is deformed. After the product 100 is placed, the bottom pressing member 312 is released, and under the action of the bottom spring 313, the bottom pressing member 312 is reset and pressed on the upper side of the bottom edge of the product 100.

[0068] The side positioning assembly 32 is arranged on the horizontal side of the side support 22 and can exert a clamping force in the horizontal direction on the side end of the product 100. The side positioning assembly 32 includes a side positioning frame 321 fixedly connected to the base 1 at the bottom; and a side pressing member 322 hingedly connected to the side positioning frame 321, which extends towards the side end of the product 100. The side pressing member 322 is approximately in the shape of a horizontal "Y", and the bifurcated end thereof faces the product 100 and is provided with a pad.

[0069] On the basis of the above-mentioned embodiments,Figure 4 A vertical rod is connected to the upper part of the bottom positioning frame 311 of the bottom positioning member 31 through vertical sliding, the upper end of the vertical rod is connected to the bottom pressing member 312, and the lower end extends downward through the upper part of the bottom positioning frame 311. Figure 6 A through hole is formed in the bottom support member 21 in the horizontal direction, and an operating rod 314 is arranged in the through hole.

[0070] Through the lever structure formed by the operating rod 314 and the bottom support member 21, a bottom spring 313 with a large force can be used, the bottom spring 313 is arranged around the vertical rod, and the two ends of the bottom spring 313 are located between the upper part of the bottom positioning frame 311 and the operating rod 314.

[0071] When the product 100 is placed, the operating rod 314 is pressed downward by the worker, the other end of the operating rod 314 lifts the vertical rod, so that the bottom pressing member 312 moves upward, and at this time, the bottom spring 313 is compressed.

[0072] The side pressing member 322 and the side positioning frame 321 of the side positioning member 32 only need to be connected through hinging, and a torsional spring is arranged at the connection position, so that the side pressing member 322 can press the product 100.

[0073] On the basis of the above-mentioned embodiments, referring to Figure 5 and Figure 6 , the fixed detection unit 4 comprises a positioning pin detection assembly 41 and a vertical surface detection assembly 42.

[0074] As shown in Figure 5 , a horizontal connecting plate is arranged on the product 100, a connecting hole is formed in the connecting plate, and the positioning pin detection assembly 41 is used for detecting the structure. The positioning pin detection assembly 41 comprises a positioning pin detection table 411, the positioning pin detection table 411 is fixedly arranged on the base 1, a plug hole corresponding to the positioning hole of the product 100 is formed in the positioning pin detection table 411, and a recess corresponding to the connecting plate of the product 100 is formed at the position where the plug hole is arranged.

[0075] After product 100 is placed, the positioning pin detection post 412 can be inserted into the connecting plate of product 100 from top to bottom. If the positioning pin detection post 412 can pass through the connecting plate normally and be inserted into the positioning pin detection table 411, it indicates that the setting position of the connecting plate is correct. Then, the upper surface of the connecting plate and the upper surface of the notch can be measured with a surface gauge. If the measurement result is 0mm, it indicates that the position of the connecting plate is qualified.

[0076] Based on the above implementation scheme, the vertical surface inspection assembly 42 includes a vertical surface inspection table 421, which is a vertically arranged boss fixedly mounted on the upper surface of the base 1. The vertical surface inspection table 421 also has a recess corresponding to the vertical surface structure of the product 100 to be inspected. Figure 6 As shown, this structure corresponds to the plate structure on the horizontal side of product 100, such as a limiting plate, baffle, etc. Assuming the limiting plate is the structure to be inspected horizontally on product 100, provided product 100 is qualified and placed normally in support unit 2, the notch of the vertical inspection table 421 must ensure a gap between its lower surface and the bottom surface of the limiting plate, while the upper surface of the vertical inspection table 421 is flush with the upper surface of the limiting plate. Using this structure, the position of the lower surface of the limiting plate can be quickly measured using the notch of the vertical inspection table 421 and a feeler gauge, while the upper surface of the limiting plate can be measured using a combination of the upper surface of the vertical inspection table 421 and a surface difference gauge, making the measurement process intuitive and quick.

[0077] Based on the above implementation scheme, the active detection unit 5 includes two parallel slide rails 51, which are fixedly connected to the base 1. The length direction of the slide rails 51 is parallel to the length direction of the product 100. An active detection frame 52 is slidably connected to the slide rails 51, and the active detection frame 52 can slide along the slide rails 52. A first detection element 53 and a second detection element 54 are respectively provided on the active detection frame 52. The first detection element 53 is slidably connected to the active detection frame 52 and can detect the rib position 101 in the horizontal direction of the product 100. The second detection element 54 is movably connected to the active detection frame 52 and is a dial indicator. The second detection element 54 is used to detect the protrusion 102 on the horizontal side of the product 100.

[0078] The number of first inspection pieces 53 and second inspection pieces 54 can be set according to the actual situation. (See attached document.) Figure 9The first detection member 53 is a horizontal rod, and one sleeve is arranged at one end of the rod, which is arranged towards the product 100. If the sleeve can be sleeved outside the muscle position 101 of the product 100, it indicates that the structure of the muscle position 101 is qualified. The second detection member 54 is horizontally inserted into the movable detection frame 52, and the detection end thereof is arranged towards the product 100. Only the structure of the second detection member 54 is arranged at the corresponding position of the convex block 102 of the product 100, and the movable detection frame 52 can be used for detecting the structure of the convex block 102. In addition, a dial gauge zero reset part is arranged on the base 1, so as to facilitate the zero reset of the dial gauge.

[0079] On the basis of the above-mentioned embodiments, because the number of the muscle position 101 and the convex block 102 to be detected can be large, in order to ensure the detection position of the movable detection frame 52, the positioning of the movable detection frame 52 on the slide rail 51 also needs to be considered. Therefore, the movable detection unit 5 further comprises a fixing structure, which is arranged corresponding to the slide rail 51 and the movable detection frame 52. The movable detection frame 52 can be fixed on the slide rail 51 through the fixing structure.

[0080] The present application provides a specific implementation form of the fixing structure. A positioning rod 53 is arranged in parallel on one side of the slide rail 51. A plurality of insertion holes for positioning the movable detection frame 52 are arranged on the rod body of the positioning rod 53. A first positioning member 54 is arranged on the movable detection frame 52. The first positioning member 54 comprises a screw rod, which is threadedly connected with the bottom plate of the movable detection frame 52 and can be inserted into the insertion hole on the positioning rod 53 after penetrating through the movable detection frame 52.

[0081] In addition, a plurality of positioning tables 55 are arranged between the two slide rails 51. The positioning tables 55 are arranged corresponding to the positions of the product 100 to be detected, such as the muscle position 101. The insertion holes are also arranged on the positioning tables 55. A second positioning member 56 is arranged corresponding to the movable detection frame 52. The second positioning member 56 is in the form of an insertion rod, and a return spring is arranged between the second positioning member 56 and the movable detection frame 52. When the second positioning member 56 is inserted into the positioning table 55, it indicates that the movable detection frame 52 reaches the detection position of the muscle position 101.

[0082] In the description of the present application and the embodiments thereof, it should be understood that the terms "top", "bottom", "height" and the like indicate the orientation or positional relationship shown in the drawings, and are only used for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0083] In the present application and embodiments thereof, unless specifically defined otherwise, the terms "set", "mounted", "connected", "linked", "fixed" and the like are to be construed broadly in accordance with the principles of equivalence in the art, such that for example, "connected" can mean fixedly connected, or removably connected, or integrally connected, or mechanically connected, or electrically connected, or communicatively connected, or directly connected, or indirectly connected, or connected via an intermediary, or interconnected, or interacting, or related through the interconnection of two or more elements. Those skilled in the art will appreciate that the terms "set", "mounted", "connected", "linked", "fixed" and the like, as used in the present application, are not to be construed as limiting the scope of the present application.

[0084] In the present application and embodiments thereof, unless specifically defined otherwise, a first feature "on", "above", or "under" a second feature can include the first and second features being directly in contact, or the first and second features not being directly in contact but being in contact through another feature between them. Also, a first feature "on", "above", and "over" a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is at a higher horizontal level than the second feature. A first feature "under", "below", and "underneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is at a lower horizontal level than the second feature.

[0085] The above disclosure provides many different embodiments or examples for implementing different structures of the present application. For the sake of brevity, the descriptions of the specific examples in the above are described in a manner that is not limiting. It will be apparent to those skilled in the art that other embodiments and examples can be practiced without departing from the spirit and scope of the application. For example, specific numbers of elements, materials, and configurations are not to be construed as limiting, but rather as set forth in the following claims. In addition, the present application contemplates that many of the components and / or steps described herein can be implemented in a computer- readable medium having stored thereon computer-executable instructions that, when executed by one or more processors, carry out the methods described herein. The present application contemplates that the components and / or steps may

[0086] While the preferred embodiments of the application have been described above, it will be recognized and understood that various modifications and changes can be made to the application by those skilled in the art that will achieve the spirit of the application. For example, the order of steps can be changed, or various steps can be changed, or eliminated. It is therefore intended that the appended claims be construed to include all such modifications and changes as fall within the true spirit and scope of the application.

[0087] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover the modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A positioning and measuring device for long products, characterized in that, include: Abutment, including a long, narrow abutment plate; A support unit is fixedly installed on the upper side of the base. The support unit and the base are fixedly connected. The support unit can support the product to be tested. A positioning unit is disposed on the base, and the positioning unit can fix the bottom or sides of the product; A fixed detection unit is fixedly mounted on the base. The fixed detection unit is located on the side of the support unit and can detect the vertical shape and structure of the product. The active detection unit is slidably connected to the base, and its sliding direction is the length direction of the product. The active detection unit can detect the horizontal structure of the product.

2. The positioning and measuring device for long products as described in claim 1, characterized in that, The support unit includes: The bottom support is a long strip structure, which is vertically installed on the upper surface of the base and can be attached to the bottom surface of the product. A side support is provided at each end of the bottom support along its length, and a notch is provided on the side support corresponding to the side edge of the product.

3. The positioning and measuring device for long products as described in claim 2, characterized in that, The bottom support component includes: At least two bottom bosses are provided on the upper side of the bottom support member. The two bottom bosses extend vertically upward and the upper end face of the bottom boss abuts against the bottom surface of the product. At least one bottom support column is fixedly installed on the upper surface of the bottom support member, and the upper surface of the bottom support column abuts against the bottom surface of the product.

4. The positioning and measuring device for long products as described in claim 2, characterized in that, The positioning unit includes: The bottom positioning component is located on one side of the bottom support member and can apply a clamping force from top to bottom to the lower part of the product; A side positioning component, disposed on the horizontal side of the side support, can apply a horizontal clamping force to the side end of the product.

5. The positioning and measuring device for long products as described in claim 4, characterized in that, The bottom positioning component includes: The bottom positioning frame is fixedly connected to the base. The bottom pressure component is vertically and slidably connected to the bottom positioning frame; A bottom spring is disposed between the bottom positioning frame and the bottom pressure member.

6. The positioning and measuring device for long products as described in claim 4, characterized in that, The side positioning component includes: The side positioning frame is fixedly connected to the base. The side pressure member is hinged to the side positioning frame, and extends toward the side end of the product.

7. The positioning and measuring device for long products as described in claim 2, characterized in that, The fixed detection unit includes: The positioning pin detection component can detect the positioning holes on the product; The vertical surface inspection component can inspect the upper and lower surfaces of corresponding structures on a product.

8. The positioning and measuring device for long products as described in claim 7, characterized in that, The positioning pin detection component includes: A positioning pin testing platform is fixedly mounted on the base, and the positioning pin testing platform has insertion holes corresponding to the product positioning holes; The positioning pin detection post can be inserted into the socket on the positioning pin detection platform; The vertical plane detection component includes: The vertical surface inspection table is a vertically set boss with a notch that corresponds to the vertical surface structure of the product to be inspected.

9. The positioning and measuring device for long products as described in claim 7, characterized in that, The activity detection unit includes: The slide rail is fixedly connected to the base, and the length direction of the slide rail is parallel to the length direction of the product. The movable testing frame is slidably connected to the slide rail, allowing the movable testing frame to slide along the slide rail. The first detection element is slidably connected to the movable detection frame, and the first detection element can detect the ribs in the horizontal direction of the product; The second testing component is movably connected to the movable testing frame, and the second testing component is a dial indicator.

10. The positioning and measuring device for long products as described in claim 9, characterized in that, The activity detection unit further includes: A fixed structure is provided corresponding to the slide rail and the movable detection frame. The movable detection frame can be fixed on the slide rail by the fixed structure.

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