Erecting device for instruments and equipment at observation window of experimental space

Abstract

The invention relates to an erecting device for instruments and equipment at an observation window of an experiment space. The erecting device comprises a flange plate, a threading connecting part, a connecting frame, a fastening part, an erecting platform, a clamp and a suspension cable. A first threaded blind hole and a second threaded blind hole are formed in the upper portion and the lower portion of one end of the flange plate respectively, each first threaded blind hole is in threaded connection with a threading connecting part, the fastening part penetrates through a cross rod of the connecting frame to be in threaded connection with the second threaded blind hole, and the connecting frame is fixed to the flange plate; one end of the erecting platform is connected with the longitudinal rod of the connecting frame through a clamp, and the clamp is adjusted to enable the erecting platform to move or be fixed to any position in the vertical direction of the longitudinal rod. And the suspension cable is connected with the erection platform and the threading connection part. The device can achieve stepless adjustment, is suitable for different instruments and equipment, and is high in universality, simple in structure and low in cost. During installation, a lens of the observation window can be prevented from being damaged, and an existing flange plate can be directly transformed or replaced with a new flange plate to be additionally used for installing the connecting frame.

Description

Technical Field

[0001] The invention relates to the technical field of experimental equipment, and in particular to a device for mounting instruments and equipment at an observation window of an experimental space. Background Art

[0002] With the rapid development of science and technology, technologies in various fields are booming, such as aerospace, medicine, chemistry, physics and other fields, which all need to carry out relevant simulation experiments, such as wind tunnels, various aircraft flight state simulation experiments under low pressure, vacuum experiments, poison gas experiments, nuclear material properties experiments, non-contact experiments under sterile conditions, etc., which require closed spaces or near-vacuum closed spaces. Generally, such experiments require the installation of instruments and equipment at the observation window to measure relevant experimental data of the internal space through the observation port.

[0003] For experimental spaces such as wind tunnels, vacuum tanks, sterile chambers and other closed tanks or boxes, their observation windows are generally a certain distance from the ground and may not match the height of the corresponding instruments and equipment. It is generally difficult for instruments and equipment to align the lens or signal transmitter with the observation window without auxiliary tooling. In addition, due to the high requirements for adjustment precision, the auxiliary tooling is currently mostly designed individually according to the sizes of different instruments and equipment, with a long design cycle and high cost. Summary of the invention

[0004] The purpose of the present invention is to provide a device for installing instruments and equipment at an observation window of an experimental space, so as to solve at least one problem existing in the background technology.

[0005] In order to achieve the above object, the present invention provides a device for mounting instruments and equipment at an observation window of an experimental space, comprising:

[0006] A flange, wherein at least one first threaded blind hole is provided at the upper portion of one end, and at least two second threaded blind holes are provided at intervals at the lower portion, and each first threaded blind hole is threadedly connected to a threading connection portion;

[0007] A connecting frame, comprising a plurality of longitudinal bars arranged in parallel and spaced apart and a cross bar vertically connecting the plurality of longitudinal bars, wherein the cross bar is provided with a first through hole corresponding to the second threaded blind hole, and the fastening portion passes through the first through hole and is threadedly connected to the second threaded blind hole, thereby fixing the connecting frame on the flange;

[0008] The erection platform is used to support instruments and equipment. At least two clamps are connected to one end of the erection platform. Each clamp cooperates with a longitudinal rod. When locked, the clamp is fixed relative to the longitudinal rod, and when released, it can move along the vertical direction of the longitudinal rod.

[0009] A hanging cable is connected to the erection platform at one end and to the threading connection portion at the other end.

[0010] Optionally, the longitudinal rod is a round rod;

[0011] The clamp includes a U-shaped clamp, a first bolt and a first nut. The U-shaped clamp includes an arc segment matching the round rod and straight segments arranged at both ends of the arc segment. The two straight segments are arranged in parallel and spaced apart, and second through holes are provided on the two straight segments. The two second through holes are coaxially arranged. The first bolt passes through the two second through holes and cooperates with the first nut. The U-shaped clamp can be deformed by rotating the first nut.

[0012] Optionally, a rubber layer or a sponge layer is provided at least on the inner side of the arc section of the U-shaped clamping plate.

[0013] Optionally, the erection platform includes a flat plate and two baffles, a plurality of slots are arranged at intervals on the flat plate, and each baffle can be inserted into any of the slots.

[0014] Optionally, the erection platform is connected to the clamp via a rotating member, so that the erection platform can rotate relative to the clamp.

[0015] Optionally, the rotating member includes an annular seat, a bearing, a rotating rod and a connecting rod. The annular seat is fixedly connected to the clamp, the outer ring of the bearing is fixedly connected to the annular seat, the rotating rod extends through the bearing and is fixedly connected to the inner ring of the bearing, and both ends of the rotating rod are fixedly connected to the mounting platform through the connecting rod.

[0016] Optionally, the number of the first threaded blind hole is one;

[0017] The suspension cable is in a herringbone shape, with one end having a wire end connected to the wire threading connection part, and the other end having two wire ends respectively connected to two places of the erection platform; or

[0018] There are two suspension cables, and one end of each of the two suspension cables is connected to the threading connection part, and the other end is respectively connected to two locations of the erection platform.

[0019] Optionally, the number of the first threaded blind holes is two;

[0020] There are two suspension cables, one end of the two suspension cables is respectively connected to the two threading connection parts, and the other end of the two suspension cables is respectively connected to two locations of the erection platform.

[0021] Optionally, the threading connection portion includes a second bolt and a second nut, the shank of the second bolt is threadedly connected to the first threaded blind hole, the second nut is threadedly connected to the shank of the second bolt and abuts against the flange, and a threading hole is provided on the second bolt, and the threading hole is located between the second nut and the head of the second bolt; and / or

[0022] The fastening part includes a stud, a third nut and a fourth nut. The stud passes through the first through hole and is threadedly connected with the second threaded blind hole. The third nut and the fourth nut are connected to the stud and are respectively located on both sides of the cross bar.

[0023] Optionally, an annular groove is provided at the other end of the flange, and the annular groove surrounds the center hole of the flange and is connected to the center hole.

[0024] The above technical solution of the present invention has the following advantages:

[0025] The apparatus for mounting instruments and equipment at the observation window of the experimental space provided by the present invention comprises a flange, a threading connection part, a connecting frame, a fastening part, a mounting platform, a clamp and a hanging cable. A first threaded blind hole is provided at the upper part of one end of the flange, and two second threaded blind holes are provided at the lower part. Each first threaded blind hole is threadedly connected with a threading connection part, and the fastening part passes through the cross bar of the connecting frame and is threadedly connected with the second threaded blind hole, and the connecting frame is fixed on the flange. One end of the mounting platform is connected to the longitudinal rod of the connecting frame through a clamp. When locked, the clamp is fixed relative to the longitudinal rod, and can move along the vertical direction of the longitudinal rod when loosened. One end of the hanging cable is connected to the mounting platform, and the other end is connected to the threading connection part. It can realize stepless adjustment, can be applicable to different instruments and equipment, has strong versatility, simple structure and low cost. It can avoid damage to the lens of the observation window during installation, and the existing flange can be directly modified for installing the connecting frame, or a new flange can be replaced for installing the connecting frame.

[0026] The device for mounting instruments and equipment at the observation window of the experimental space provided by the present invention has a mounting platform connected to a clamp through a rotating member, so that the mounting platform can rotate relative to the clamp to achieve angle adjustment of the mounting platform, and further achieve angle adjustment of the instruments and equipment to meet more testing and observation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings of the present invention are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not necessarily be consistent with the actual products.

[0028] Figure 1 It is a front view schematic diagram of a device for mounting instruments and equipment at an observation window of an experimental space in the first embodiment of the present invention;

[0029] Figure 2 yes Figure 1 A schematic diagram of the left side of the middle mounting device;

[0030] Figure 3 is a front view schematic diagram of a flange in Embodiment 1 of the present invention;

[0031] Figure 4 yes Figure 3 Schematic diagram of the rear view of the middle flange;

[0032] Figure 5 middle Figure 4 AA section diagram in;

[0033] Figure 6It is a structural schematic diagram of a mounting platform in Embodiment 1 of the present invention;

[0034] Figure 7 It is a schematic diagram of the structure of a threading connection part in the first embodiment of the present invention;

[0035] Figure 8 is a structural schematic diagram of a fastening portion in Embodiment 1 of the present invention;

[0036] Fig. 9 It is a front view schematic diagram of a device for installing instruments and equipment at an observation window of an experimental space in the second embodiment of the present invention;

[0037] Fig.10 It is a front view schematic diagram of a device for mounting instruments and equipment at an observation window of an experimental space in the third embodiment of the present invention;

[0038] Fig.11 It is a side view schematic diagram of a device for mounting instruments and equipment at an observation window of an experimental space in a fourth embodiment of the present invention;

[0039] Fig.12 It is a structural schematic diagram of a mounting platform in Embodiment 4 of the present invention.

[0040] In the figure:

[0041] 1: Flange;

[0042] 11: first threaded blind hole;

[0043] 12: Second threaded blind hole;

[0044] 13: annular groove;

[0045] 14: center hole;

[0046] 15: Sealing ring;

[0047] 2: Threading connection part;

[0048] 21: second bolt;

[0049] 211: threading hole;

[0050] 22: second nut;

[0051] 3: Connecting frame;

[0052] 31: vertical bar;

[0053] 32: horizontal bar;

[0054] 4: Fastening part;

[0055] 41: stud;

[0056] 42: the third nut;

[0057] 43: fourth nut;

[0058] 5: Set up the platform;

[0059] 51: Tablet;

[0060] 511: card slot;

[0061] 512: tie-line hole;

[0062] 52: baffle;

[0063] 6: Clamp;

[0064] 61: U-shaped splint;

[0065] 62: first bolt;

[0066] 63: first nut;

[0067] 64: rubber layer;

[0068] 7: Suspension cable;

[0069] 8: Rotating parts;

[0070] 81: annular seat;

[0071] 82: rotating rod;

[0072] 83: Connecting rod. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0074] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0075] Furthermore, the terms “first”, “second”, and “third” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0076] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] Embodiment 1

[0078] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a device for mounting instruments at an observation window of an experimental space, comprising a flange 1, a threading connection portion 2, a connecting frame 3, a fastening portion 4, a mounting platform 5, a clamp 6 and a hanging cable 7.

[0079] See also Figure 3 and Figure 4 As shown, two first threaded blind holes 11 are arranged at intervals on the upper part of one end of the flange 1, and two second threaded blind holes 12 are arranged at intervals on the lower part, and each first threaded blind hole 11 is threadedly connected to a threading connection portion 2. It should be noted that the flange 1 can be a new flange that matches the shape of the observation window and is manufactured using the solution of the present application; threaded blind holes can also be directly processed on the original flange, which is not limited here.

[0080] See also Figure 1 and Figure 2 As shown, the connecting frame 3 includes two longitudinal rods 31 arranged in parallel and spaced apart and a cross rod 32 vertically connecting the plurality of longitudinal rods 31. The cross rod 32 is provided with a first through hole corresponding to the second threaded blind hole 12. The fastening portion 4 passes through the first through hole and is threadedly connected to the second threaded blind hole 12 to fix the connecting frame 3 on the flange 1.

[0081] See also Figure 1 , Figure 2 and Figure 6 As shown, the erection platform 5 is used to support instruments and equipment. Two clamps 6 are connected to one end of the erection platform 5, each clamp 6 cooperates with a longitudinal rod 31, and the clamp 6 is fixed relative to the longitudinal rod 31 when locked, and can move along the vertical direction of the longitudinal rod 31 when loosened (unlocked).

[0082] See also Figure 1 and Figure 2 As shown, two suspension cables 7 are used in this embodiment, one end of the two suspension cables 7 is connected to the erection platform 5, and the other end is connected to the threading connection part 2. The suspension cables 7 and the clamps 6 cooperate with each other and are used together to fix the erection platform 5.

[0083] When in use, the mounting device is fixed to the observation window of the experimental space such as the closed tank or box such as the wind tunnel, vacuum tank, sterile warehouse, etc. through the flange, the lower end of the connecting frame is against the ground, the instruments and equipment are placed on the mounting platform, and the height of the mounting platform is adjusted to align the instruments and equipment with the observation window of the experimental space to meet the experimental needs. When adjusting the height of the mounting platform, the mounting platform is moved by loosening the clamp, and the clamp is locked when it is moved to the appropriate position, and the hanging cable is adjusted to fix the mounting platform in the appropriate position. The entire adjustment process is stepless adjustment, which can better meet the fineness requirements of the adjustment compared to the existing hydraulic lifting. In addition, it can be applied to different instruments and equipment, has strong versatility, simple structure and low cost. In addition, it is safer during installation. During installation, the flange can be connected to the observation window first, and then the connecting frame can be installed on the flange. Since the connection between the connecting frame and the flange is realized through a threaded blind hole, it is avoided that the connection between the flange and the observation window is affected during installation, thereby avoiding the optical glass such as the lens at the observation window from being broken due to uneven force on the flange when the connecting frame is installed. In addition, due to the use of blind holes, the existing flange can be directly modified to install the connecting frame, and a new flange can be replaced to install the connecting frame.

[0084] In some embodiments, see Figure 2 and Figure 6 The longitudinal rod 31 is a round rod. The clamp 6 includes a U-shaped clamp 61, a first bolt 62 and a first nut 63. The U-shaped clamp 61 includes an arc segment matching the round rod and straight segments arranged at both ends of the arc segment. The two straight segments are arranged in parallel and spaced apart, and second through holes are arranged on the two straight segments. The two second through holes are coaxially arranged. The first bolt 62 passes through the two second through holes and cooperates with the first nut 63. The U-shaped clamp 61 can be deformed by rotating the first nut 63, thereby clamping the longitudinal rod 31 or releasing the clamping.

[0085] In order to increase friction and improve the clamping effect, in some embodiments, see Figure 6 As shown, at least a rubber layer 64 or a sponge layer is provided on the inner side of the arc section of the U-shaped clamping plate 61 .

[0086] In order to adapt to instruments and equipment of different sizes and provide a certain degree of fixation for the instruments and equipment, in some embodiments, see Figure 1 , Figure 2 and Figure 6As shown, the mounting platform 5 includes a flat plate 51 and two baffles 52. A plurality of slots 511 are arranged at intervals on the flat plate 51. Each baffle 52 can be inserted into any slot 511. The instrument is placed between the two baffles 52. The distance between the two baffles 52 is adjusted by the baffle 52 cooperating with different slots 511. In addition, the slots 511 can increase the friction between the instrument and the flat plate 51. It should be noted that the shape of the baffle 52 can be any matching shape according to the different shapes of the instrument. For example, the baffle 52 can be a straight plate, a curved plate, or a combination of a straight plate and a curved plate, which is not limited here.

[0087] Preferably, see Figure 6 As shown, the flat plate 51 is provided with a cable hole 512 for connecting with a hanging cable.

[0088] The threading connection part 2 can adopt any structure capable of threading, for example, a radially perforated stud, a screw, etc. In some embodiments, see Figure 2 and Figure 7 As shown, the threading connection part 2 includes a second bolt 21 and a second nut 22. The rod of the second bolt 21 is threadedly connected to the first threaded blind hole 11. The second nut 22 is threadedly connected to the rod of the second bolt 21 and abuts against the flange 1, which facilitates the connection and strengthens the fixing effect of the second bolt 21 and the flange 1. A threading hole 211 is provided on the second bolt 21, and the threading hole 211 is located between the second nut 22 and the head of the second bolt 21, which facilitates the passing and fixing of the suspension cable 7.

[0089] The fastening part 4 can be any fastener, for example, a screw, a bolt, a stud and a nut. Figure 1 , Figure 2 and Figure 8 As shown, the fastening part 4 includes a stud 41, a third nut 42 and a fourth nut 43. The stud 41 passes through the first through hole and is threadedly connected to the second threaded blind hole 12. The third nut 42 and the fourth nut 43 are threadedly connected to the stud 41 and are respectively located on both sides of the cross bar 32. The structure of the fastening part 4 is that the two nuts cooperate with the stud, on the one hand, the connection frame 3 can be fixed more firmly, and on the other hand, the distance between the connection frame 3 and the flange 1 can be adjusted by the nut located between the cross bar 32 and the flange 1, thereby achieving fine adjustment of the distance between the erection platform 5 and the flange 1, that is, achieving fine adjustment of the distance between the instrument and the observation window.

[0090] In order to better achieve the clamping and fixing of the lens at the observation window, in one embodiment, see Figure 4 and Figure 5As shown, an annular groove 13 is provided at the other end of the flange 1 (the end facing the observation window), and the annular groove 13 surrounds the center hole 14 of the flange 1 and is connected to the center hole 14, that is, the annular groove 13 is a sinking groove with an L-shaped cross section. Preferably, a sealing ring 15 is provided in the annular groove 13.

[0091] In this embodiment, the suspension cable 7 is made of nylon rope or other cables with good flexibility and toughness.

[0092] Embodiment 2

[0093] like Fig. 9 As shown, the second embodiment is basically the same as the first embodiment, and the similarities are not repeated here. The difference is that a first threaded blind hole 11 is provided at the upper part of one end of the flange 1, and a threading connection part 2 is threadedly connected at the first threaded blind hole 11. There are two suspension cables 7, and each of the two suspension cables 7 has one end connected to the threading connection part 2, and the other end is respectively connected to two places of the mounting platform 5 to form a triangle fixation.

[0094] Embodiment 3

[0095] like Fig.10 As shown, the third embodiment is basically the same as the first embodiment, and the similarities are not repeated here. The difference is that the suspension cable 7 is in a herringbone shape, that is, one end has a wire end connected to the threading connection part 2, and the other end has two wire ends, which are respectively connected to two places of the mounting platform 5. Only one adjustment is required, which makes the adjustment more convenient.

[0096] Embodiment 4

[0097] like Fig.11 and Fig.12 As shown, based on any one of the mounting devices in Examples 1 to 3, the mounting platform 5 is connected to the fixture 6 through a rotating member 8, so that the mounting platform 5 can rotate relative to the fixture 6, thereby achieving angle adjustment of the mounting platform 5, and further achieving angle adjustment of the instrument to meet more testing and observation requirements.

[0098] The rotating member 8 can be realized by a hinge structure or the like. In one embodiment, see Fig.12As shown, the rotating member 8 includes an annular seat 81, a bearing (not shown in the figure), a rotating rod 82 and a connecting rod 83. The annular seat 81 is fixedly connected to the clamp 6 (it can be welded or integrally connected, etc., which is not limited here), the outer ring of the bearing is fixedly connected to the annular seat 81, the rotating rod 82 extends through the bearing and is fixedly connected to the inner ring of the bearing, and both ends of the rotating rod 82 are fixedly connected to the erection platform 5 through the connecting rod 83. By adjusting the suspension cable 7, the angle of the erection platform 5 can be changed. In this process, the rotating rod 82 rotates relative to the annular seat 81. This process is also stepless adjustment, which further realizes fine adjustment to meet more experimental requirements.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that not every embodiment contains only one independent technical solution. In the absence of a conflict of solutions, the various technical features mentioned in each embodiment can be combined in any manner to form other implementation methods that can be understood by those skilled in the art.

[0100] In addition, without departing from the scope of the present invention, the technical solutions described in the aforementioned embodiments may be modified, or some of the technical features may be replaced by equivalents, without causing the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for mounting instruments and equipment at an observation window of an experimental space, characterized in that: include: A flange, wherein at least one first threaded blind hole is provided at the upper portion of one end, and at least two second threaded blind holes are provided at intervals at the lower portion, and each of the first threaded blind holes is threadedly connected to a threading connection portion; A connecting frame, comprising a plurality of longitudinal bars arranged in parallel and spaced apart and a cross bar vertically connecting the plurality of longitudinal bars, wherein the cross bar is provided with a first through hole corresponding to the second threaded blind hole, and the fastening portion passes through the first through hole and is threadedly connected with the second threaded blind hole, so as to fix the connecting frame on the flange; A mounting platform for supporting instruments and equipment, wherein at least two clamps are connected to one end of the mounting platform, each of the clamps cooperates with one of the longitudinal rods, and when locked, the clamps are fixed relative to the longitudinal rod, and when released, they can move in the up and down directions of the longitudinal rod; A hanging cable has one end connected to the erection platform and the other end connected to the threading connection portion.

2. The mounting device according to claim 1, characterized in that: The longitudinal rod is a round rod; The clamp includes a U-shaped clamp, a first bolt and a first nut. The U-shaped clamp includes an arc segment matching the round rod and straight segments arranged at both ends of the arc segment. The two straight segments are arranged in parallel and spaced apart, and second through holes are provided on the two straight segments. The two second through holes are coaxially arranged. The first bolt passes through the two second through holes and cooperates with the first nut. The U-shaped clamp can be deformed by rotating the first nut.

3. The mounting device according to claim 2, characterized in that: At least a rubber layer or a sponge layer is provided on the inner side of the arc section of the U-shaped clamping plate.

4. The mounting device according to claim 1, characterized in that: The erection platform comprises a flat plate and two baffles. A plurality of slots are arranged at intervals on the flat plate, and each of the baffles can be inserted into any of the slots.

5. The mounting device according to claim 1, characterized in that: The erection platform is connected to the clamp via a rotating member, so that the erection platform can rotate relative to the clamp.

6. The mounting device according to claim 5, characterized in that: The rotating member includes an annular seat, a bearing, a rotating rod and a connecting rod. The annular seat is fixedly connected to the clamp, the outer ring of the bearing is fixedly connected to the annular seat, the rotating rod extends through the bearing and is fixedly connected to the inner ring of the bearing, and both ends of the rotating rod are fixedly connected to the mounting platform through connecting rods.

7. The mounting device according to claim 1, 5 or 6, characterized in that: The number of the first threaded blind hole is one; The suspension cable is in a herringbone shape, with one end having a wire end connected to the threading connection portion, and the other end having two wire ends respectively connected to two locations of the erection platform; or There are two suspension cables, each of which has one end connected to the threading connection portion and the other end connected to two locations of the erection platform respectively.

8. The mounting device according to claim 1, 5 or 6, characterized in that: The number of the first threaded blind holes is two; There are two suspension cables, one end of the two suspension cables is respectively connected to the two threading connection parts, and the other end of the two suspension cables is respectively connected to two locations of the erection platform.

9. The mounting device according to claim 1, characterized in that: The threading connection portion comprises a second bolt and a second nut, the shank of the second bolt is threadedly connected to the first threaded blind hole, the second nut is threadedly connected to the shank of the second bolt and abuts against the flange, a threading hole is provided on the second bolt, and the threading hole is located between the second nut and the head of the second bolt; and / or The fastening portion includes a stud, a third nut and a fourth nut. The stud passes through the first through hole and is threadedly connected to the second threaded blind hole. The third nut and the fourth nut are connected to the stud and are respectively located on both sides of the cross bar.

10. The mounting device according to claim 1, characterized in that: An annular groove is provided at the other end of the flange, and the annular groove surrounds the central hole of the flange and is communicated with the central hole.

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