An integrating sphere turntable used in a vacuum environment

Abstract

The invention discloses an integrating sphere turntable for use in a vacuum environment, comprising a concentric turntable outer ring, an upper ring, a supporting cylinder, a large polytetrafluoroethylene gasket, a lower ring, and a chassis frame. The upper ring, the large polytetrafluoroethylene gasket, and the lower ring are slidably connected in sequence from top to bottom to form an annular sliding assembly. The supporting cylinder is sleeved within the annular sliding assembly, the turntable outer ring is sleeved outside the annular sliding assembly, the upper edge of the turntable outer ring covers the annular sliding assembly, a gap is provided between the inner wall of the turntable outer ring and the annular sliding assembly, the supporting cylinder is fixedly connected to the upper ring, the turntable outer ring is connected to the chassis frame, the lower ring is fixedly connected to the chassis frame, the supporting cylinder carries an infrared integrating sphere, and the diameter of the turntable outer ring is smaller than that of the infrared integrating sphere. The invention solves the problem of carrying and maintaining an integrating sphere in a vacuum high and low temperature environment. The invention is smaller and more beautiful than a traditional frame structure and can be used as a universal carrier for integrating spheres.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared optics and vacuum mechanical equipment, and in particular to an integrating sphere turntable used in a vacuum environment. Background Art

[0002] Infrared radiation, also known as infrared and thermal radiation, has a wavelength range of 700nm to 1000um, lying between visible light and microwaves. Any object with a temperature above absolute zero continuously radiates infrared radiation. The higher the temperature, the greater the radiation intensity and the shorter the wavelength. In infrared optics, there is a huge demand for low-temperature, background-free, or low-background infrared light sources, particularly those with known radiance, high stability, and high uniformity. To this end, we have researched and identified a suitable illuminant. Combining this with mother-and-child integrating sphere technology and spherical shell coil cooling, the entire system is placed in a vacuum tank. This simulates the vacuum and low-temperature environment of space, solving a range of problems in infrared optics and detection, demonstrating its broad and versatile application.

[0003] To complement this infrared light source technology, the engineering team developed an integrating sphere light source. Optical performance tests demonstrated its properties and advantages. While the lifespan of this infrared illuminator is theoretically expected to reach several thousand hours, maintenance and replacement remain challenges. To address this, the structural design optimized the space constraints within the vacuum tank and the significant temperature fluctuations. This resulted in a turntable that allows the 70-80kg integrating sphere system to rotate slightly left and right. The primary limitation is the copper tubes and bellows, which restrict rotation. Any greater rotation angle could result in excessive force on these tubes, potentially causing refrigerant leaks and other serious issues, not a problem with the turntable itself. With this 120° rotation, the integrating sphere's light outlet, previously facing the interior of the tank, now faces the side, effectively presenting the side of the integrating sphere system to maintenance personnel. The two sub-spheres in the front half of the mother ball can be opened to replace the lamps, and the other two sub-spheres can be replaced by rotating them to the other side.

[0004] There are many structures that can rotate. At the beginning of development, we first considered thrust bearings. Bearings are inherently rotatable. However, with a turntable diameter exceeding 250mm, the bearings themselves were already very large, and the weight and height were unacceptable. This was because we had to ensure that the optical axis of the integrating sphere's light outlet was aligned with the tank's centerline and the subsequent infrared optical path. Oil lubrication and general plastics cannot be used in vacuum tanks. PTFE material effectively solved and replaced the role of rolling bearings. PTFE's pressure resistance, lubrication, and high temperature resistance effectively solved the turntable's rotation problem. Combined with a stainless steel rotating bracket, it effectively solved the rotation and support, locking and positioning, and preventing dislodgment.

[0005] Therefore, those skilled in the art are committed to developing an integrating sphere turntable for use in a vacuum environment to overcome the problems existing in the prior art. Summary of the Invention

[0006] In view of the aforementioned shortcomings of the prior art, the present invention aims to provide an integrating sphere turntable for use in a vacuum environment. This solves the problem of rotating the integrating sphere system in vacuum high and low temperature environments. The system comprises multiple copper tubes for the parent and child spheres, which are connected to a refrigerator outside the tank via a pressure-resistant bellows of a certain length, achieving refrigeration and temperature control for the parent and child spheres. The infrared light emitted by the infrared illuminator primarily converts into infrared radiation to illuminate the entire integrating sphere, which is then output through the light outlet. A portion of this energy is converted into heat, which is then channeled through the copper tubes to remove excess heat. The turntable can rotate ±120° within the relatively compact space of a vacuum tank, facilitating maintenance. It can hold the integrating sphere and lock it in place, allowing for long-term storage within the tank with minimal maintenance. The integrating sphere and base are perfectly integrated outside the vacuum tank, resulting in a sleek and simple appearance, resembling a large globe. The low support height makes the integrating sphere's support nearly impossible to detect without bending over, avoiding the traditional design of securing the integrating sphere with a flange, such as a square tube bracket, which is typically larger than the integrating sphere itself.

[0007] To achieve the above-mentioned objectives, the present invention provides an integrating sphere turntable for use in a vacuum environment, comprising a concentrically arranged turntable outer ring, an upper ring, a supporting cylinder, a large polytetrafluoroethylene gasket, a lower ring, and a chassis frame, wherein the upper ring, the large polytetrafluoroethylene gasket, and the lower ring are slidably connected in sequence from top to bottom to form an annular sliding assembly, the supporting cylinder is sleeved in the annular sliding assembly, the turntable outer ring is sleeved outside the annular sliding assembly, the turntable outer ring has an upper edge, the upper edge covers the annular sliding assembly, and there is a gap between the inner wall of the turntable outer ring and the annular sliding assembly, the supporting cylinder is fixedly connected to the upper ring, the turntable outer ring is connected to the chassis frame, the lower ring is fixedly connected to the chassis frame, the supporting cylinder is configured to carry an infrared integrating sphere, and the diameter of the turntable outer ring is smaller than the diameter of the infrared integrating sphere.

[0008] Furthermore, the turntable outer ring, upper ring, supporting cylinder and lower ring are all made of stainless steel.

[0009] Furthermore, the support cylinder is connected to the upper ring by welding, and the lower ring is connected to the chassis frame by welding.

[0010] Furthermore, a pair of notches and a pair of stainless steel ears are respectively provided at mutually orthogonal positions on the top of the support cylinder, and the stainless steel ears are welded to the support cylinder.

[0011] Furthermore, a fixing hole is provided on the stainless steel support ear, and a small round polytetrafluoroethylene gasket is provided above the fixing hole. The height of the small round polytetrafluoroethylene gasket is adjustable. The fixing hole corresponds to the position of the anchor point welded on the infrared integrating sphere, and the stainless steel support ear and the anchor point are connected by bolts through the fixing hole.

[0012] Furthermore, the width of the notch is consistent with the flange width of the infrared integrating sphere, and the rear edge of the notch is provided with a chamfer that forms a 30° angle with the vertical plane.

[0013] Furthermore, the supporting cylinder is made of a stainless steel pipe of standard specifications.

[0014] Furthermore, the opposing surfaces of the upper ring and the lower ring are made by a precision turning process.

[0015] Furthermore, three locking screw through holes are evenly opened on the circumference of the outer ring of the turntable, and the outer ring of the turntable is configured to be able to be locked with the chassis frame by at least two locking screws passing through the corresponding locking screw through holes.

[0016] Furthermore, when the turntable outer ring is locked with the chassis frame, the upper edge of the turntable outer ring clamps the upper ring, so that the supporting cylinder and the turntable outer ring do not rotate relative to each other.

[0017] The advantages of the present invention are:

[0018] The present invention solves the problem of integrating sphere bearing and rotation maintenance in vacuum high and low temperature environments. Outside the vacuum tank, it is also an ideal integrating sphere bearing structure. It is smaller and more beautiful than the traditional frame structure, and can be used as a universal integrating sphere carrier to achieve fixation and rotation. The overall height of the turntable is low, which is conducive to reducing the overall height of the integrating sphere and increasing the stability of the integrating sphere system; the turntable system is smaller than the diameter of the integrating sphere, saying goodbye to the traditional frame structure that is generally larger than the integrating sphere and flange. The structural design is ingenious, and the appearance is beautiful and exquisite. You need to bend down to find the supporting structure. Looking around, it looks like a large globe. The turntable rotates flexibly and has appropriate friction torque. It moves when pushed by hand and stops when released by hand. The turntable is made entirely of ordinary stainless steel and polytetrafluoroethylene materials, and is made through reasonable processes and multiple welding and assembly processes, with very low cost.

[0019] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a cross-sectional view of a turntable according to a preferred embodiment of the present invention;

[0021] Figure 2 1 is a component diagram of a turntable according to a preferred embodiment of the present invention;

[0022] Figure 3 This is an enlarged view of the notch of the turntable of a preferred embodiment of the present invention;

[0023] Figure 4 1 is a top view of an integrating sphere turntable according to a preferred embodiment of the present invention;

[0024] Figure 5 This is a system diagram of an integrating sphere and a rotating disk according to a preferred embodiment of the present invention;

[0025] Figure 6 is a right side cross-sectional view of an integrating sphere and a rotating disk according to a preferred embodiment of the present invention;

[0026] Figure 7 is a front cross-sectional view of an integrating sphere and a rotating disk according to a preferred embodiment of the present invention;

[0027] Figure 8 This is a system diagram of another preferred embodiment of the present invention, in which the integrating sphere and the turntable are located in a narrow space between a heat sink and a long bracket;

[0028] Figure 9 This is a front view of another preferred embodiment of the present invention, in which the integrating sphere and the turntable are located in a narrow space between a heat sink and a long bracket.

[0029] Among them, A1-turntable outer ring, A2-stainless steel upper ring, A3-stainless steel support cylinder, A4-PTFE large gasket, A5-stainless steel lower ring, A6-PTFE small round gasket, B1-stainless steel lug, B2-cylinder notch, C1-integrating sphere flange, C2-locking screw through hole, D1-infrared integrating sphere, D2-integrating sphere turntable, E1-rectangular bracket, E2-heat sink device. DETAILED DESCRIPTION

[0030] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0031] In the drawings, components with identical structures are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrary and are not limited by the present invention. For clarity, the thickness of components in some places in the drawings is appropriately exaggerated.

[0032] Example 1

[0033] like Figure 1-7As shown, the vacuum integrating sphere turntable includes an outer turntable ring A1, a stainless steel upper ring A2, a stainless steel support cylinder A3, a large PTFE gasket A4, a stainless steel lower ring A5, and a small PTFE gasket A6. The stainless steel upper ring A2 is 6 mm thick; the outer turntable ring A1 has an outer diameter of φ306 mm and a thickness of 16.5 mm; the stainless steel support cylinder A3 has a diameter of φ258 mm, a wall thickness of 4 mm, and a height of 30 mm; the large PTFE gasket A4 is 3 mm thick; and the stainless steel lower ring A5 is 6 mm thick.

[0034] The stainless steel support cylinder A3 bears the entire weight of the infrared integrating sphere D1 through its left and right cylindrical notches B2 and its front and rear stainless steel lugs B1. During processing, the two stainless steel lugs B1 must be appropriately chamfered before welding the two lugs B1 to the stainless steel support cylinder A3. Two M8 bolts are then used to connect the infrared integrating sphere D1 and the stainless steel support cylinder A3. However, the weight of the integrating sphere primarily rests on the left and right cylindrical notches B2. These notches B2 are essentially rectangular, 12mm wide and 10mm high, and face upward, bearing the majority of the sphere's weight. The rear edge of the notches B2 is chamfered at a 30° angle to the vertical plane to facilitate hoisting and placement of the integrating sphere. This also prevents relative rotation and displacement between the infrared integrating sphere D1 and the stainless steel support cylinder A3.

[0035] like Figure 1 The figure shows a cross-sectional view of the turntable. The integrating sphere turntable is essentially a non-detachable sliding thrust bearing. The maximum diameter is the turntable outer ring A1: φ306mm, and the overall maximum height is only 40mm, which includes the height of the PTFE gasket. The turntable outer ring A1 is connected to the chassis frame and does not rotate. The stainless steel support cylinder A3 and the stainless steel upper ring A2 carry the integrating sphere and can be rotated manually, which is equivalent to the shaft ring of the thrust bearing. The large PTFE gasket A4 plays a role similar to the steel ball and retainer of the thrust ball bearing: it carries axial force and reduces rotational friction. The stainless steel lower ring A5 also does not rotate. It is welded to the chassis frame and does not rotate, which is equivalent to the seat ring of the thrust ball bearing. The contact surfaces of the stainless steel upper ring A2 and the stainless steel lower ring A5 are precision-machined to a very high level of roughness. They are pressed into contact with the PTFE surface to provide moderate friction. Reasonable drawing design, welding, assembly and other processes and procedures are used to form this independently developed non-detachable sliding thrust bearing. Various materials can be used in a vacuum for a long time, without the need for any grease lubrication, no vacuum volatilization, and basically maintenance-free.

[0036] This integrating sphere turntable was completed through careful design, reasonable welding and assembly processes. It can not only well carry the infrared integrating sphere weighing more than 70kg, but also realize the rotation of the integrating sphere in the vacuum tank, which is convenient for inspection and maintenance.

[0037] like Figure 2 The figure shows the components of the turntable. The integrating sphere is primarily supported and positioned by two cylindrical notches B2 on the left and right stainless steel support cylinder A3. Two front and rear stainless steel lugs B1 secure the sphere with screws. B1 is made of a 60mm long, 40mm wide, and 5mm thick stainless steel angle steel. The total extension length is 351mm, and the mounting hole is 330mm. If the height is not ideal, the two small PTFE round washers A6 can be modified or replaced. The maximum dimensions of the integrating sphere turntable are 351mm long, 306mm wide, and 40mm high, which are much smaller than the SD600mm inner diameter of the integrating sphere. The integrating sphere bracket, previously fabricated using conventional square steel pipe welding, has external dimensions of 692mm wide, 800mm deep, and 380mm high. It is secured with flanges. Due to the offset center of gravity, and for safety and reliability, the overall dimensions are much larger than the SD600mm inner diameter of the integrating sphere.

[0038] like Figure 3 The image shown is an enlarged view of the turntable notch. The infrared integrating sphere's flange C1 is inserted into the cylindrical notch B2. The thickness of the integrating sphere's flange C1 is 12mm, and the notch width is also 12mm. With the appropriate tolerances, it fits snugly. The 30° chamfer facilitates the installation of the infrared integrating sphere.

[0039] like Figure 4 The figure shows a top view of the integrating sphere turntable. Through the three φ6.5 locking screw through holes C2 evenly distributed at 120° on the outer circle of the turntable, the integrating sphere turntable can be locked at the 0° and ±120° positions respectively by 2-3 M6 screws.

[0040] like Figure 5 As shown in the figure, it is the overall system diagram of the integrating sphere and the turntable. The infrared integrating sphere D1 is securely placed on the integrating sphere turntable D2. It is simple and easy to use when placed inside the vacuum tank, and it is equally easy to use when placed outside, achieving a harmonious unity with the integrating sphere. From a distance, it looks like a large globe, adding points and color to the appearance of the infrared integrating sphere!

[0041] like Figure 6 The figure shows a cross-sectional right view of the integrating sphere and the turntable. The integrating sphere turntable D2 supports the entire infrared integrating sphere D1 very well, achieving all functions with a smaller size and lighter weight.

[0042] like Figure 7 As shown in the front view of the cross section of the integrating sphere and turntable, the integrating sphere turntable D2 is simple, practical and easy to use! It can be said to be a relatively perfect structural design!

[0043] Example 2

[0044] like Figure 8-9As shown, this embodiment is similar to Example 1, differing in that the chassis frame in this embodiment is a rectangular bracket E1, whose length aligns with that of the heat sink E2. The integrating sphere turntable D2 is mounted on the rectangular bracket E1. The infrared integrating sphere D1 and the integrating sphere turntable D2 are located in the confined space formed by the heat sink E2 and the rectangular bracket E1. The heat sink E2 has a diameter of 1000 mm and contains multiple bellows and copper tubes. Refrigerant fluid flows through the bellows and copper tubes to facilitate overall cooling of the infrared integrating sphere D1. The sophisticated design of the integrating sphere turntable system meets the requirements for installation and maintenance of the infrared integrating sphere D1 in confined spaces similar to those of this embodiment.

[0045] The integrating sphere turntable used in a vacuum environment of the present invention is realized by the following technical solutions:

[0046] The integrating sphere turntable D2 supports the entire integrating sphere system. As the sphere rotates, it is subject to some pulling force from the bellows. The turntable's anti-slip structure mitigates this force. The turntable's outer ring A1 is machined from stainless steel and connected to the chassis frame (a rectangular frame in this embodiment). The outer ring is stationary, while the inner ring (the stainless steel support cylinder A3) is constructed from a large, standard stainless steel tube (e.g., φ258mm diameter, 4mm wall thickness). Two L-shaped stainless steel lugs B1 are welded to the inner ring of the inner ring. These lugs B1 are fixed to the anchor points of the front and rear hemispheres of the integrating sphere using two M8 screws. The anchor points of the front and rear hemispheres are designed based on the center of gravity of the integrating sphere. In addition to the two lugs, the rotating inner ring (stainless steel support cylinder A3) features two slots (cylinder notches B2) that precisely engage the integrating sphere's flange C1. The slots' entrances are appropriately chamfered to facilitate the lifting and insertion of the integrating sphere's flange C1. Once flange C1 is engaged, the sphere's gravity primarily rests on these two slots. Teflon gaskets allow for subtle adjustments in front and back contact between the lugs and anchor points, essentially ensuring four-point support for the integrating sphere's weight. This is easily achieved through structural design drawings and the associated processes and procedures.

[0047] The integrating sphere turntable for use in a vacuum environment of the present invention can be used in a vacuum environment, does not require rotating bearings, does not contain oil, has a simple turntable structure, a large load-bearing capacity, moderate damping, and flexible rotation. It has a better rotation feel than ball bearings or thrust bearings, is noiseless during rotation, and can be locked in several required positions. The core of the turntable system uses polytetrafluoroethylene as the relatively rotating material, and the stainless steel ring in contact with the polytetrafluoroethylene is precision-machined and smooth, equivalent to a homemade sliding bearing. The overall height is very low, basically lower than the height of all other bearings. The disk has a small diameter, ingenious load-bearing ability, and a beautiful and simple appearance. The overall appearance is equivalent to a large globe. The infrared integrating sphere we developed weighs about 70 kilograms, but the turntable can be rotated with one hand, moving when pushed and stopping when released.

[0048] The integrating sphere turntable used in the vacuum environment of the present invention only requires simple and minor changes to be made to the integrating sphere flange, and basically maintains the original annular shape of the front and rear flanges. The shape is very simple, and only two symmetrical notches need to be processed at appropriate positions on the flange, and the position of the flange bottom plate is slightly cut flat, so that it can be docked and positioned with this turntable. It is also necessary to weld two anchor points on the front and rear hemispheres. The anchor points of the front and rear hemispheres are designed according to the center of gravity of the integrating sphere and are used to fix and lock the integrating sphere. Two M8 screws are used to lock and fix it. Since we use a vacuum infrared gold-plated integrating sphere, it is necessary to coil a copper tube on the spherical shell to control the refrigeration temperature of the sphere. The anchor points can be welded tangentially to the front and rear hemispheres in the loop gap where the copper tube is coiled, and there is no effect on the coil of the spherical shell.

[0049] The main structural parts are welded with stainless steel, and the rotating core parts are made of polytetrafluoroethylene. Both can work in a vacuum environment for a long time, can withstand high-temperature baking of about 120°C in a vacuum environment, and can withstand vacuum low temperatures of about -80°C in the tank body. They are dust-free, oil-free, and volatile-free.

[0050] The turntable system adopts reasonable procedures and ingenious design. The PTFE material is first embedded in the stainless steel turntable. After stainless steel argon arc welding, the turntable system will not fall out or fall apart. It can be connected to the integrating sphere as a whole and can be moved and hoisted at will, making it convenient to transport the whole system and load it into the vacuum tank.

[0051] Theoretically, this turntable can rotate through a full range of angles, but the infrared integrating sphere it carries is placed in a vacuum tank. The sphere is wrapped and welded with copper tubing, which cools the sphere through refrigerant. High-strength bellows connect the sphere in and out of the tank, so in practice, the rotation angle cannot be too large. We require a maximum left and right rotation angle of ±120° to complete the rotation of the integrating sphere and enable the maintenance and replacement of the infrared light source on the sub-sphere. Without this turntable, the light outlet of our integrating sphere would face the inside of the vacuum tank, making it impossible to repair.

[0052] The integrating sphere turntable used in a vacuum environment of the present invention avoids the traditional design method of fixing the integrating sphere flange through a square tube bracket or the like, and the characteristic that the bracket is generally larger than the integrating sphere; when the integrating sphere is rotated to ±120°, or in the original position of 0°, screws can be used to securely lock it with the underlying chassis frame, and there is no unexpected rotation.

[0053] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. An integrating sphere turntable used in a vacuum environment, characterized in that: It includes a concentrically arranged turntable outer ring, an upper ring, a supporting cylinder, a large polytetrafluoroethylene gasket, a lower ring, and a chassis frame. The upper ring, the large polytetrafluoroethylene gasket, and the lower ring are slidably connected in sequence from top to bottom to form an annular sliding assembly. The supporting cylinder is sleeved in the annular sliding assembly, and the turntable outer ring is sleeved outside the annular sliding assembly. The turntable outer ring has an upper edge, and the upper edge covers the annular sliding assembly. There is a gap between the inner wall of the turntable outer ring and the annular sliding assembly. The supporting cylinder is fixedly connected to the upper ring, the turntable outer ring is connected to the chassis frame, and the lower ring is fixedly connected to the chassis frame. The supporting cylinder is configured to carry an infrared integrating sphere, and the diameter of the turntable outer ring is smaller than the diameter of the infrared integrating sphere.

2. The integrating sphere turntable for use in a vacuum environment according to claim 1, wherein: The outer ring of the turntable, the upper ring, the supporting cylinder and the lower ring are all made of stainless steel.

3. The integrating sphere turntable for use in a vacuum environment according to claim 2, wherein: The supporting cylinder is connected to the upper ring by welding, and the lower ring is connected to the chassis frame by welding.

4. The integrating sphere turntable for use in a vacuum environment according to claim 3, wherein: A pair of notches and a pair of stainless steel ears are respectively provided at mutually orthogonal positions on the top of the support cylinder, and the stainless steel ears are welded to the support cylinder.

5. The integrating sphere turntable for use in a vacuum environment according to claim 4, characterized in that: A fixing hole is provided on the stainless steel support ear, and a small polytetrafluoroethylene round gasket is provided above the fixing hole. The height of the small polytetrafluoroethylene round gasket is adjustable. The fixing hole corresponds to the position of the anchor point welded on the infrared integrating sphere, and the stainless steel support ear and the anchor point are connected by bolts through the fixing hole.

6. The integrating sphere turntable for use in a vacuum environment according to claim 4, wherein: The width of the notch is consistent with the flange width of the infrared integrating sphere, and the rear edge of the notch is provided with a chamfer that forms a 30° angle with the vertical plane.

7. The integrating sphere turntable for use in a vacuum environment according to claim 2, wherein: The supporting cylinder is made of a stainless steel pipe of standard specifications.

8. The integrating sphere turntable for use in a vacuum environment according to claim 2, wherein: The opposite surfaces of the upper ring and the lower ring are made by a precision turning process.

9. The integrating sphere turntable for use in a vacuum environment according to claim 4, wherein: Three locking screw through holes are evenly opened on the circumference of the outer ring of the turntable. The outer ring of the turntable is configured to be able to be locked with the chassis frame by at least two locking screws passing through the corresponding locking screw through holes.

10. The integrating sphere turntable for use in a vacuum environment according to claim 9, characterized in that: When the turntable outer ring is locked with the chassis frame, the upper edge of the turntable outer ring clamps the upper ring, so that the supporting cylinder and the turntable outer ring do not rotate relative to each other.

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