Corrugated pipe fluorine lining valve

Abstract

The invention relates to the technical field of valves, in particular to a corrugated pipe fluorine lining valve which comprises a valve body, a valve rod, a corrugated pipe and a deformable valve element structure, the valve body is provided with a flow channel formed by communicating a medium inlet and a medium outlet and a valve cavity communicating with the flow channel, and the communicating position of the medium inlet and the medium outlet is a communicating opening of the flow channel; the valve rod is slidably connected to the valve body in the axial direction, and the first end of the valve rod is arranged in the valve cavity. The corrugated pipe is used for sealing the sliding joint of the valve rod and the valve body; the deformable valve element structure comprises a core plate, an elastic rubber piece and a shaft pull rod, the core plate corresponds to a communicating opening of the flow channel in position and is fixed to the first end of the valve rod, the peripheral edge of the elastic rubber piece is fixed to the core plate in a static sealing mode, and the shaft pull rod is movably arranged at the first end of the valve rod in the axial direction. And the middle part of the elastic rubber sheet protrudes to form a cone structure with constant bottom circle diameter and variable height. The frequency of axial movement of the valve rod and expansion and contraction of the corrugated pipe can be effectively reduced, and the service life of the corrugated pipe is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of valves, and particularly to a bellows lined with fluorine valve. Background Art

[0002] A fluorine-lined valve is a valve with good corrosion resistance. This kind of valve is made by pressing polytetrafluoroethylene resin on the inner wall of the steel valve body or the outside of the valve internals. It is a valve made by utilizing the performance of polytetrafluoroethylene resin in resisting strong corrosive media.

[0003] In fluorine-lined valves, bellows are also often used as one of the means for sealing the gap between the valve stem and the valve body. This kind of fluorine-lined valve using bellows as a seal is also called a bellows lined with fluorine valve. When this valve is in use, it relies on the actuator to control the axial movement of the valve stem. In this way, not only can the opening and closing of the valve be realized, but also the position of the valve core on the valve stem can be adjusted, thereby changing the opening degree of the flow channel and further controlling the flow rate of the fluid. That is to say, every time the flow rate is changed, the axial movement of the valve stem needs to be controlled, and the axial movement of the valve stem will also drive the axial expansion and contraction of the bellows. The more frequently the bellows expand and contract, the shorter its service life will be, so it needs to be replaced regularly. In view of the above problems, the present invention proposes a bellows lined with fluorine valve. Summary of the Invention

[0004] The purpose of the present invention is to provide a bellows lined with fluorine valve to solve the problems mentioned in the above background art.

[0005] The present invention is achieved through the following technical solutions: A bellows lined with fluorine valve, comprising: A valve body, having a flow channel formed by the communication of a medium inlet and a medium outlet, and a valve cavity communicating with the flow channel. The communication position of the medium inlet and the medium outlet is the communication port of the flow channel; A valve stem, slidably connected to the valve body along the axial direction and having its first end placed in the valve cavity; A bellows, used for sealing the sliding connection between the valve stem and the valve body; and A deformable valve core structure, including a core plate, an elastic film, and a shaft pull rod. The core plate corresponds to the position of the communication port of the flow channel and is fixed to the first end of the valve stem. The four peripheral edges of the elastic film are statically sealed and fixed on the core plate. The shaft pull rod is movably arranged along the axial direction at the first end of the valve stem, so that the middle part of the elastic film protrudes to form a cone structure with an unchanged bottom circle diameter and a variable height.

[0006] Optionally, a pressurizing chamber is provided on the valve stem. A piston member that divides the pressurizing chamber into a first chamber and a second chamber is slidably disposed in the pressurizing chamber. The first chamber communicates with the gap between the core plate and the elastic film, and the second chamber communicates with the valve chamber or the outside.

[0007] Optionally, the shaft pull rod is rotatable relative to the valve stem, the piston member is non-rotatable relative to the pressurizing chamber, and the piston member is threadedly connected to the valve stem.

[0008] Optionally, the shaft pull rod is provided with an external thread and a smooth surface. The piston member includes a plug body and a cylinder body. The plug body has a threaded through hole that is threadedly engaged with the external thread of the shaft pull rod. The plug body is in sliding and sealing contact with the inner wall of the pressurizing chamber through a first seal. One end of the cylinder body is fixed to the plug body, and a second seal is provided between the other end of the cylinder body and the smooth surface of the shaft pull rod.

[0009] Optionally, the piston member and the pressurizing chamber are connected by a shape-locking method to limit the rotation of the piston member relative to the pressurizing chamber.

[0010] Optionally, the end of the shaft pull rod is provided as a spherical end, and the shaft pull rod abuts against the middle of the elastic film through the spherical end.

[0011] Optionally, the shaft pull rod axially penetrates through the valve stem. An air vent hole is provided at one end of the shaft pull rod close to the elastic film, and a pressure gauge communicating with the air vent hole is connected to the other end of the shaft pull rod.

[0012] Optionally, a locking structure is provided between the shaft pull rod and the valve stem. The locking structure can selectively lock the shaft pull rod on the valve stem to limit or allow the shaft pull rod to axially move relative to the valve stem.

[0013] Optionally, the deformable valve core structure further includes a pressure ring. The pressure ring is detachably connected to one side of the core plate facing the communication port of the flow channel, and presses the periphery of the elastic film onto the core plate. A sealing flange protrudes on one side of the communication port of the flow channel facing the pressure ring.

[0014] Optionally, when the pressure ring is installed, a plurality of stud bolts are arranged circumferentially on the side facing the core plate. Mounting holes corresponding to the plurality of stud bolts are provided on the core plate. The pressure ring and the core plate are tightly connected by the cooperation of the stud bolts and fastening nuts.

[0015] Compared with the prior art, the present invention provides a bellows-lined fluorine valve, which has the following beneficial effects: The present invention adjusts the distance between the deformable valve core structure and the communication port by controlling the axial movement of the valve rod, thereby realizing the opening and closing of the valve. After the valve is opened, if it is necessary to change the flow rate of the flow channel, it can be achieved by controlling the axial movement of the shaft pull rod, without moving the valve rod again. When the shaft pull rod moves, the elastic film is lifted to form a conical shape, and the change in its height affects the sealing area, thereby controlling the fluid flow rate. This method reduces the movement frequency of the valve rod and the bellows, and extends the service life of the bellows; By providing a pressure chamber and a piston member, when using the elastic film protruding outward in a conical shape to adjust the opening degree of the communication port, the position of the piston member in the pressure chamber can be adjusted according to the pressure of the fluid in the flow channel, so that the pressures on the inner and outer sides of the elastic film are kept as consistent as possible, ensuring that the conical surface of the elastic film does not undergo excessive deformation, which is beneficial to improving the stability of the flow rate at the communication port position; In the present invention, by using the shaft pull rod as the driving component for controlling the piston member, controlling the rotation of the shaft pull rod can drive the piston member to move in the pressure chamber, thereby achieving the purpose of adjusting the air pressure inside the elastic film, without the need to separately provide other driving components to drive the piston member to move. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is of the present invention Figure 1 partial structure schematic diagram; Figure 3 is a schematic diagram of the connection structure between the piston member and the shaft pull rod of the present invention; Figure 4 is of the present invention Figure 1 magnified structure schematic diagram at position A.

[0017] In the figure: 100, valve body; 110, upper valve body; 120, lower valve body; 121, valve cavity; 122, medium inlet; 123, medium outlet; 124, communication port; 125, sealing flange; 126, fluorine-lined layer; 130, bolt and nut structure; 200, valve rod; 210, pressure chamber; 211, first cavity; 212, second cavity; 300, bellows; 310, sealing ring; 400, deformable valve core structure; 410, core plate; 420, elastic film; 430, shaft pull rod; 431, spherical end; 432, ventilation hole; 433, pressure gauge; 440, piston member; 441, plug body; 442, cylinder; 443, first seal; 444, second seal; 450, pressure ring; 460, stud; 470, fastening nut; 500, manual actuator; 510, positioning frame; 520, positioning piece; 530, driving handle; 540, positioning pin; 600, positioning screw. DETAILED DESCRIPTION OF THE INVENTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0019] Embodiment: Please refer to Figures 1 to 4 , a bellows fluorine-lined valve is provided according to an embodiment of the present invention, which includes a valve body 100, a valve stem 200, a bellows 300, and a deformable valve core structure 400. Among them, the valve body 100 has a flow path formed by communicating a medium inlet 122 and a medium outlet 123, and a valve cavity 121 communicating with the flow path. The communicating position of the medium inlet 122 and the medium outlet 123 is the communication port 124 of the flow path. The fluid enters from the medium inlet 122 and flows out from the medium outlet 123 after flowing through the communication port 124; the valve stem 200 is slidably connected to the valve body 100 along the axial direction, and the first end is placed in the valve cavity 121. Figure 1Among them, the axial direction is defined as the up-and-down direction, which is also the direction pointed by the central axis of the valve stem 200; the bellows 300 is used to seal the sliding connection between the valve stem 200 and the valve body 100; the deformable valve core structure 400 includes a core plate 410, an elastic film 420 and a shaft pull rod 430. The core plate 410 corresponds to the position of the communication port 124 of the flow channel and is fixed to the first end of the valve stem 200. The four peripheral edges of the elastic film 420 are statically sealed and fixed to the core plate 410. The shaft pull rod 430 is axially movably arranged at the first end of the valve stem 200 so that the middle part of the elastic film 420 protrudes to form a cone structure with an unchanged bottom circle diameter and a variable height. Specifically in this example, the valve body 100 includes a lower valve body 120 and an upper valve body 110. A valve cavity 121 is provided on the lower valve body 120. In order to improve the corrosion resistance of the inner wall of the lower valve body 120, the inner wall of the lower valve body 120 has a fluorine lining 126, and the fluorine lining 126 is polytetrafluoroethylene resin. The valve cavity 121 forms an opening on the surface of the lower valve body 120. The upper valve body 110 is fixed at the opening of the valve cavity 121 of the lower valve body 120 through a bolt and nut structure 130. The first end of the valve stem 200 is located in the valve cavity 121, and the second end of the valve stem 200 movably passes through the upper valve body 110 and extends to the outside. The valve stem 200 and the upper valve body 110 can slide relative to each other axially. The bellows 300 is located in the valve cavity 121 and sleeved on the first end of the valve stem 200. A sealing ring plate 310 is welded to the upper end of the bellows 300, and the sealing ring plate 310 is clamped and installed between the lower valve body 120 and the upper valve body 110, so that a static seal is formed between the upper end of the bellows 300 and the upper and lower valve bodies 120. The lower end of the bellows 300 is welded to the core plate 410, and the core plate 410 and the valve stem 200 can be an integral structure, so that a static seal is formed between the lower end of the bellows 300 and the valve stem 200. Thus, the bellows 300 can be used to realize the seal of the sliding connection between the valve stem 200 and the valve body 100.

[0020] The bellows-lined fluorine valve adopting the above structure can adjust the distance between the deformable valve core structure 400 and the communication port 124 by controlling the axial movement of the valve stem 200 to realize the opening and closing of the valve. After the valve is opened, if it is necessary to change the flow rate of the flow channel, it is not necessary to control the axial movement of the valve stem 200 again. Only by controlling the axial movement of the shaft pull rod 430 can the purpose of changing the flow rate be achieved. Specifically, when the shaft pull rod 430 moves axially, the elastic film 420 will be pushed up towards the communication port 124. The shape of the lifted elastic film 420 is a cone. When the shaft pull rod 430 moves axially, the bottom circle diameter of the cone will not change, but the height of the cone will change. Moreover, the higher the height of the cone, the larger the sealing area of the communication port 124, and the less fluid can pass through the communication port 124. On the contrary, the lower the height of the cone, the smaller the sealing area of the communication port 124, and the less fluid can pass through the communication port 124. In this way, within a certain range, only by controlling the axial movement of the shaft pull rod 430 can the purpose of effectively controlling the flow rate of the fluid flowing through the valve be achieved, replacing the way of changing the flow rate by controlling the axial movement of the valve stem 200 in the prior art, which can effectively reduce the frequency of the axial movement of the valve stem 200 and the expansion and contraction of the bellows 300, and prolong the service life of the bellows 300.

[0021] In order to facilitate the control of the axial movement of the valve stem 200, in some embodiments, as Figure 1 shown, a manual actuator 500 is provided on the valve body 100. The manual actuator 500 includes a positioning frame 510, a positioning piece 520, and a drive handle 530. The lower end of the positioning frame 510 is fixedly provided on the upper valve body 110. The second end of the valve stem 200 movably passes through the positioning frame 510. The positioning piece 520 is fixed on the valve stem 200 through a positioning pin 540. The positioning piece 520 and the positioning frame 510 are axially guided and matched. The drive handle 530 can be rotatably connected to the upper end of the positioning frame 510 through a bearing. The second end of the valve stem 200 is threadedly connected to the drive handle 530. By rotating the drive handle 530 forward and backward, the valve stem 200 can be driven to move axially. In other embodiments, the axial movement of the valve stem 200 can also be realized by a pneumatic actuator or an electric actuator.

[0022] On the basis of the above embodiments, in some embodiments, as Figure 2As shown, a pressure chamber 210 is provided on the valve stem 200. A piston member 440 is slidably disposed in the pressure chamber 210 to divide the pressure chamber 210 into a first chamber 211 and a second chamber 212. The first chamber 211 communicates with the gap between the core plate 410 and the elastic film 420, and the second chamber 212 communicates with the valve chamber 121 or the outside. Specifically in this embodiment, the shaft pull rod 430 movably penetrates through the valve stem 200, and there is a gap between the shaft pull rod 430 and the valve stem 200. The second chamber 212 communicates with the outside through the gap between the shaft pull rod 430 and the valve stem 200. It can be understood that when using the elastic film 420 protruding outward in a conical shape to adjust the opening degree of the communication port 124, the position of the piston member 440 in the pressure chamber 210 can be adjusted according to the pressure of the fluid in the flow channel, so that the pressures on the inner and outer sides of the elastic film are kept as consistent as possible, to ensure that the conical surface of the elastic film 420 will not undergo excessive deformation, which is beneficial to improving the stability of the flow rate at the position of the communication port 124. In other embodiments, the second chamber 212 can also be connected to the valve chamber 121 through a pipeline (not shown). At this time, the position of the piston member 440 in the pressure chamber 210 will be automatically adjusted according to the pressure of the fluid in the valve chamber 121, which can also ensure that the pressures on the inner and outer sides of the elastic film 420 are approximately the same.

[0023] Based on the above embodiments, in some embodiments, such as Figure 2 As shown, the shaft pull rod 430 is rotatable relative to the valve stem 200, the piston member 440 is non-rotatable relative to the pressure chamber 210, and the piston member 440 is threadedly connected to the valve stem 200. Specifically in this embodiment, the shaft pull rod 430 has a cylindrical structure. The shaft pull rod 430 movably penetrates through the valve stem 200 and passes through the pressure chamber 210. The piston member 440 and the pressure chamber 210 are connected by a shape-locking method to limit the rotation of the piston member 440 relative to the pressure chamber 210. More specifically, the piston member 440 has a square structure. Correspondingly, the pressure chamber 210 is provided as a rectangular hole arranged axially. The piston member 440 can move axially in the pressure chamber 210 but cannot rotate. The outer side wall of the piston member 440 is in close contact with the inner wall of the pressure chamber 210, which can prevent air from flowing through. It can be understood that by using the shaft pull rod 430 as the driving component for controlling the piston member 440, rotating the shaft pull rod 430 can drive the piston member 440 to move in the pressure chamber 210, so as to achieve the purpose of adjusting the air pressure inside the elastic film 420, without the need to separately set other driving components to drive the piston member 440 to move.

[0024] Based on the above embodiments, in some embodiments, such as Figure 3As shown, the shaft tie rod 430 is provided with an external thread and a smooth surface. The piston member 440 includes a plug body 441 and a cylinder body 442. The plug body 441 has a threaded through hole that is threadedly engaged with the external thread of the shaft tie rod 430. A first seal 443 is in sliding sealing contact between the plug body 441 and the inner wall of the pressurizing chamber 210. One end of the cylinder body 442 is fixed to the plug body 441, and a second seal 444 is provided between the other end and the smooth surface of the shaft tie rod 430. Specifically in this embodiment, both the first seal 443 and the second seal 444 are sealing rings. With such a setting, the first seal 443 can prevent air from passing through the contact gap between the piston member 440 and the pressurizing chamber 210, and the second seal 444 can prevent air from passing through the connection position between the piston member 440 and the shaft tie rod 430. This enables the first chamber 211 to maintain good airtightness when the piston member 440 moves, thereby improving the stability of the air pressure inside the elastic film 420.

[0025] Based on the above embodiments, in some embodiments, such as Figure 2 and Figure 3 As shown, the end of the shaft tie rod 430 is provided as a spherical end 431, and the shaft tie rod 430 abuts against the middle of the elastic film 420 through the spherical end 431. By setting the end of the shaft tie rod 430 as a spherical end 431, the contact area between the end of the shaft tie rod 430 and the elastic film 420 can be increased and the uniform force on the contact surface can be improved, thus being able to extend the service life of the elastic film 420.

[0026] Based on the above embodiments, in some embodiments, such as Figure 2 and Figure 3 As shown, the shaft tie rod 430 axially penetrates through the valve stem 200 movably. An air vent 432 is provided at one end of the shaft tie rod 430 close to the elastic film 420, and a pressure gauge 433 connected to the air vent 432 is connected to the other end of the shaft tie rod 430. With such a setting, the pressure gauge 433 can intuitively display the air pressure inside the elastic film 420, facilitating the user to adjust the air pressure inside the elastic film 420 as needed.

[0027] Based on the above embodiments, in some embodiments, such as Figure 4As shown, a locking structure is provided between the shaft rod 430 and the valve stem 200. The locking structure can selectively lock the shaft rod 430 to the valve stem 200, thereby limiting or allowing axial movement of the shaft rod 430 relative to the valve stem 200. Specifically, in this embodiment, the locking structure is a set screw 600, which is threaded onto the side wall of the valve stem 200. When the set screw 600 is tightened, the end of the set screw 600 can press against the shaft rod 430, thereby limiting axial movement of the shaft rod 430 relative to the valve stem 200. Of course, it also limits rotation of the shaft rod 430 relative to the valve stem 200. When the set screw 600 is loosened, the fixation of the shaft rod 430 is released. It can be understood that the locking structure can conveniently control the relative position of the shaft rod 430 and the valve stem 200. Of course, the specific form of the locking structure is not particularly limited as long as the relative position of the shaft rod 430 and the valve stem 200 can be controlled.

[0028] Based on the above embodiments, in some embodiments, such as Figure 2 As shown, the deformable valve core structure 400 also includes a pressure ring 450, which is detachably connected to the side of the core plate 410 facing the flow channel communication port 124 and presses the four sides of the elastic film 420 against the core plate 410. The flow channel communication port 124 is provided with a sealing flange 125 protruding from the side of the pressure ring 450. Specifically, in this embodiment, when the pressure ring 450 is installed, a plurality of studs 460 are arranged along the circumference on the side facing the core plate 410. The core plate 410 is provided with mounting holes corresponding to the plurality of studs 460. The pressure ring 450 and the core plate 410 are connected and fastened by the studs 460 and the fastening nuts 470. With this arrangement, when the elastic film 420 is damaged, it can be easily disassembled and replaced. Specifically, when the elastic film 420 is damaged, the fastening nuts 470 can be removed from the studs 460 to remove the elastic film 420.

[0029] Working Principle: The valve is opened and closed by controlling the axial movement of the valve stem 200 to adjust the distance between the deformable valve core structure 400 and the communication port 124. After the valve is opened, the flow rate can be changed by controlling the axial movement of the shaft rod 430 without moving the valve stem 200 again. When the shaft rod 430 moves, the elastic film 420 is lifted to form a cone shape. The height change affects the sealing area, thereby controlling the fluid flow rate. This method reduces the frequency of movement of the valve stem 200 and the bellows 300, extending the service life of the bellows 300.

[0030] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A bellows fluorine-lined valve, characterized in that, Comprising: A valve body (100) having a flow channel formed by connecting a medium inlet (122) and a medium outlet (123), and a valve cavity (121) communicating with the flow channel, wherein the connecting position of the medium inlet (122) and the medium outlet (123) is the connecting port (124) of the flow channel; A valve stem (200) slidably connected to the valve body (100) along the axial direction and having a first end disposed within the valve cavity (121); A bellows (300) for sealing the sliding connection between the valve stem (200) and the valve body (100); And A deformable valve core structure (400) including a core plate (410), an elastic film (420), and a shaft pull rod (430). The core plate (410) corresponds to the position of the connecting port (124) of the flow channel and is fixed to the first end of the valve stem (200). The four peripheral edges of the elastic film (420) are statically sealed and fixed to the core plate (410). The shaft pull rod (430) is movably disposed along the axial direction at the first end of the valve stem (200) such that the middle part of the elastic film (420) protrudes to form a cone structure with an unchanged bottom circle diameter and a variable height.

2. The corrugated pipe lined with fluorine valve according to claim 1, characterized in that: A pressure chamber (210) is provided on the valve stem (200), and a piston member (440) that divides the pressure chamber (210) into a first chamber (211) and a second chamber (212) is slidably disposed within the pressure chamber (210). The first chamber (211) communicates with the gap between the core plate (410) and the elastic film (420), and the second chamber (212) communicates with the valve cavity (121) or the outside.

3. The bellows fluorine-lined valve according to claim 2, characterized in that: The shaft pull rod (430) is rotatable relative to the valve stem (200), the piston member (440) is non-rotatable relative to the pressure chamber (210), and the piston member (440) is threadedly connected to the valve stem (200).

4. The bellows fluorine-lined valve according to claim 3, characterized in that: The shaft pull rod (430) is provided with an external thread and a smooth surface. The piston member (440) includes a plug body (441) and a cylinder body (442). The plug body (441) has a threaded through hole that is threadedly engaged with the external thread of the shaft pull rod (430). The plug body (441) is in sliding sealing contact with the inner wall of the pressure chamber (210) through a first seal (443). One end of the cylinder body (442) is fixed to the plug body (441), and a second seal (444) is provided between the other end and the smooth surface of the shaft pull rod (430).

5. The corrugated pipe lined with fluorine valve according to claim 3 or 4, characterized in that: The piston member (440) is connected to the pressure chamber (210) by means of shape locking to restrict the rotation of the piston member (440) relative to the pressure chamber (210).

6. The bellows (300) fluorine-lined valve according to any one of claims 1 to 4, characterized in that: The end of the shaft pull rod (430) is provided as a spherical end (431), and the shaft pull rod (430) abuts against the middle part of the elastic film (420) through the spherical end (431).

7. The bellows fluorine-lined valve according to any one of claims 1 to 4, characterized in that: The shaft tie rod (430) axially moves through the valve stem (200) in a penetrating manner. One end of the shaft tie rod (430) close to the elastic film (420) is provided with a vent hole (432), and the other end of the shaft tie rod (430) is connected to a pressure gauge (433) communicated with the vent hole (432).

8. The corrugated pipe lined with fluorine valve according to claim 7, characterized in that: A locking structure is arranged between the shaft tie rod (430) and the valve stem (200). The locking structure can selectively lock the shaft tie rod (430) on the valve stem (200) to restrict or allow the shaft tie rod (430) to axially move relative to the valve stem (200).

9. The corrugated pipe fluorine-lined valve according to claim 1, wherein: The deformable valve core structure (400) further includes a pressing ring (450). The pressing ring (450) is detachably connected to one side of the core plate (410) facing the communication port (124) of the flow channel, and presses the periphery of the elastic film (420) on the core plate (410). A sealing flange (125) is prominently arranged on one side of the communication port (124) of the flow channel facing the pressing ring (450).

10. The bellows fluorine-lined valve according to claim 9, characterized in that: When the pressing ring (450) is installed, a plurality of stud bolts (460) are arranged circumferentially on one side facing the core plate (410). Mounting holes corresponding to the plurality of stud bolts (460) are formed in the core plate (410). The pressing ring (450) and the core plate (410) are connected and fastened through the cooperation of the stud bolts (460) and fastening nuts (470).

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