Magnetic spike anchoring support

Abstract

The utility model belongs to the technical field of railway construction, and particularly relates to a magnetic type spike anchoring support which comprises a bottom frame body and two spike positioners arranged at intervals, the bottom frame body is used for being placed in a rail bearing groove of a sleeper, the spike positioners and the bottom frame body are relatively fixed, and U-shaped positioning grooves matched with the upper ends of spikes in size are formed in the spike positioners. Magnets used for attracting the spikes are embedded in the U-shaped positioning grooves, the distance between the two U-shaped positioning grooves is equal to the distance between the two anchoring holes in the rail bearing groove, and positioning rings matched with the lower ends of the spikes in size and allowing the spikes to penetrate through are correspondingly arranged on the portion, below the spike positioners, of the bottom frame body. The distance between the two positioning rings is equal to the distance between the two anchoring holes in the rail bearing groove, and a supporting frame in a vertical state is jointly connected between the two positioning rings and the two spike positioners. The upper end and the lower end of the spike can be positioned at the same time, and the positioning precision is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to railway construction technical field, concretely relates to a magnetic attraction formula way nail anchoring support. BACKGROUND

[0002] The most important function of the way nail is to fix the rail on the sleeper firmly, prevent the rail from displacement, shifting or lifting when the train runs, ensure the rail always keeps in the correct position, maintain the geometric shape and dimensional accuracy of the track, and provide stable and safe track for the train.

[0003] When the train runs on the rail, it will produce huge vertical load and horizontal load, the way nail as the connecting component between the rail and the sleeper can effectively transmit the train load to the sleeper, and then the sleeper evenly disperses the load to the track bed and subgrade, avoids the damage of the rail due to excessive local stress, and ensures the overall stability and bearing capacity of the track structure. The way nail is installed on the sleeper according to certain spacing and mode, and cooperates with other track components such as fasteners, pads and the like, can accurately keep the gauge between the rails, so that the wheels of the train can run smoothly within the appropriate gauge range, prevent abnormal contact and wear between the wheels and the rail, and reduce the risk of derailment and other accidents.

[0004] The way nail is generally connected to the sleeper in the form of anchoring, that is, a hole position for anchoring the way nail is drilled or reserved on the sleeper, the prepared anchoring agent is poured into the anchoring hole, then the way nail is quickly inserted into the hole, and a special tool is used to rotate and press down the way nail, so that the way nail is fully anchored in the sulfur anchoring agent, and the air and excess anchoring agent in the hole are discharged. During the anchoring process of the way nail, the perpendicularity, center deviation and anchoring depth of the way nail need to be accurately positioned, because once the anchoring accuracy of the way nail is not enough, the connection between the rail and the sleeper will be unstable; when the train runs, the rail will displace and deform due to the pressure and impact force of the wheels, so that the gauge, levelness, height difference and other geometric dimensions of the track change, exceed the allowable range, and affect the stability and comfort of the train running; in addition, poor anchoring accuracy of the way nail may also cause the way nail to be unable to effectively fix the rail on the sleeper, and with the frequent passing of the train, the rail and the sleeper will gradually loosen, which may further cause the loosening of the entire track structure, seriously threatening the stability and safety of the track.

[0005] To solve the above problems, the patent for utility model with publication No. CN203420189U discloses a magnetic type anchoring frame, which comprises two spaced apart thread peg locators for adsorbing thread pegs, the positions of the two thread peg locators match the positions of the thread peg fixing holes on the rail bearing groove, and the thread peg locators are composed of U-shaped grooves and magnets positioned on the U-shaped grooves. The magnetic type anchoring frame can adsorb and fix the thread pegs in the U-shaped grooves by the magnets, and the U-shaped grooves mainly limit and guide the upper part of the thread peg to a certain extent, so that the thread peg can keep a relatively stable posture during installation and prevent it from excessively deviating in the horizontal direction. However, the positioning effect on the lower end of the thread peg is very limited, and the specific position of the lower end of the thread peg entering the sleeper cannot be accurately controlled, and there is a certain positioning error. Content of the utility model

[0006] The utility model discloses a magnetic type thread peg anchoring support, to solve the technical problem of low positioning accuracy of the magnetic type thread peg anchoring support in the prior art.

[0007] To solve the above problems, the utility model provides a magnetic type thread peg anchoring support adopts the following technical scheme:

[0008] The magnetic type thread peg anchoring support comprises a chassis body and two spaced apart thread peg locators, the chassis body is used for being placed in the rail bearing groove of the sleeper, the thread peg locators are relatively fixed with the chassis body, and the thread peg locators are provided with U-shaped positioning grooves matched with the upper end size of the thread peg, magnets for adsorbing the thread peg are embedded in the U-shaped positioning grooves, the distance between the two U-shaped positioning grooves is equal to the interval between the two anchoring holes on the rail bearing groove, the chassis body is correspondingly provided with positioning rings matched with the lower end size of the thread peg below each thread peg locator, the distance between the two positioning rings is equal to the interval between the two anchoring holes on the rail bearing groove, and a support frame in an upright state is connected between the two positioning rings and the two thread peg locators.

[0009] The magnetic type thread peg anchoring support of the utility model can position the upper end of the thread peg through the U-shaped positioning groove and the magnet on the thread peg locator, ensure the position accuracy of the upper end of the thread peg on the horizontal plane, position the lower end of the thread peg through the positioning ring, ensure the position accuracy of the lower end of the thread peg in the horizontal direction, accurately align the anchoring hole on the sleeper, and realize the positioning of the lower end of the thread peg in the vertical direction. The thread peg locator and the positioning ring cooperate with each other to simultaneously position and constrain the upper end and the lower end of the thread peg, improve the positioning accuracy of the thread peg, and enable the thread peg to be accurately and stably installed on the sleeper.

[0010] Furthermore, the road stud locator includes an integrally formed arc-shaped upright plate and a limiting upright plate connected to both ends of the arc-shaped upright plate. The inner side of the limiting upright plate is coplanar with the inner arc surface of the arc-shaped upright plate. The arc-shaped upright plate has a concave arc-shaped embedding groove formed by stamping. The magnet is an arc-shaped magnet adapted to the arc-shaped embedding groove.

[0011] Beneficial effects: Using an arc-shaped magnet can better fit the shape of the track spike, increasing the contact area between the arc-shaped magnet and the track spike, and making the adsorption force more evenly distributed; the arc-shaped magnet is embedded in the arc-shaped positioner, and the two form a whole, making the adsorption and positioning of the track spike more accurate.

[0012] Furthermore, the arc-shaped embedding groove is located at the middle height of the arc-shaped vertical plate.

[0013] Furthermore, the bottom surface of the positioning ring is an inclined surface that fits into the bottom of the rail groove, and the central hole of the positioning ring is coaxial with the anchoring hole.

[0014] Furthermore, both the base frame and the support frame are telescopic frames that can be retracted and extended in the spaced direction of the two road spike positioners.

[0015] Beneficial effects: After the base frame and support frame are retracted, the overall size of the magnetic rail spike anchor bracket is reduced, saving more space and making it easier to store and transport during mass production.

[0016] Furthermore, the base frame includes two first connecting rods and two second connecting rods. The two first connecting rods are arranged parallel to each other along the length of the sleeper, and the two second connecting rods are perpendicularly connected to the bottom of the two first connecting rods and arranged parallel to each other along the width of the sleeper. The first connecting rods are used to contact the bottom of the rail support groove. The support frame includes two uprights and two support rods. The two support rods are respectively connected to the top and bottom of the two uprights. The two ends of the upper support rod are respectively connected to two rail spike positioners, and the two ends of the lower support rod are respectively connected to two positioning rings. The side of the positioning ring facing away from the support rod is connected to the corresponding first connecting rod through a third connecting rod. Both the second connecting rods and the support rods are telescopic rods.

[0017] Beneficial effects: The structure of the base frame and support frame is simple, making it easy to source materials and install.

[0018] Furthermore, the support rod includes a first support rod segment, a sliding rod segment, and a second support rod segment arranged coaxially. The outer diameter of the first support rod segment is equal to the outer diameter of the second support rod segment and greater than the outer diameter of the sliding rod segment. The sliding rod segment is fixed to the second support rod segment and slides in cooperation with the first support rod segment. At least one of the support rods has a locking and limiting structure between the first support rod segment and the sliding rod segment of that support rod. The locking and limiting structure gives the sliding rod segment a first locking position and a second locking position. When the sliding rod segment is in the first locking position, the opposite ends of the first support rod segment and the second support rod segment are in a stop contact. When the sliding rod segment is in the second locking position, the distance between the two U-shaped positioning grooves is equal to the distance between the two anchoring holes on the rail bearing groove.

[0019] Beneficial effects: During use, operators do not need to use additional measuring tools to measure the distance between the two road spike positioners. After sliding the slide bar to the second locking position and locking it, the road spike can be positioned directly. In addition, during production and transportation, after sliding the slide bar to the first locking position and locking it, it can be ensured that there is no relative sliding between the slide bar and the first support bar during transportation, thus ensuring the stability of the transportation process.

[0020] Furthermore, the locking and limiting structure includes a first limiting block, a second limiting block, and a locking rod. The first limiting block and the second limiting block are both fixed on the first support rod segment and arranged at intervals. The locking rod is T-shaped and includes a horizontal segment and a vertical segment. The vertical segment is perpendicularly connected to the sliding rod segment and slidably assembled with the first support rod segment. The first limiting block and the second limiting block are provided with coaxial through holes for the horizontal segment to pass through. The two ends of the horizontal segment are respectively provided with external threads.

[0021] Beneficial effects: Simple structure, easier locking and unlocking.

[0022] Furthermore, the inner diameter of the positioning ring is larger than the inner diameter of the arc-shaped upright plate. Both the first support rod segment and the second support rod segment located on the lower side are provided with clearance openings for avoiding the positioning ring. The first support rod segment and the second support rod segment located on the lower side have pressing surfaces at the clearance openings for pressing against the side and top surfaces of the positioning ring. Attached Figure Description

[0023] The above and other objects, features, and advantages of the present invention will become readily understood by reading the following detailed description of exemplary embodiments with reference to the accompanying drawings. In the drawings, several embodiments of the present invention are shown by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0024] Figure 1 This is a top view of Embodiment 1 of the magnetic rail spike anchor bracket of this utility model;

[0025] Figure 2 for Figure 1AA section view;

[0026] Figure 3 for Figure 1 BB cross-sectional view;

[0027] Figure 4 This is a schematic diagram of a road stud locator.

[0028] Figure 5 This is a schematic diagram of railway sleepers;

[0029] Figure 6 This is a schematic diagram of Embodiment 2 of the magnetic rail spike anchor bracket of this utility model.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Base frame; 2. Rail spike positioner; 3. Positioning ring; 4. Sleeper; 5. Rail bearing groove; 6. U-shaped positioning groove; 7. Magnet; 9. First connecting rod; 10. Second connecting rod; 11. Third connecting rod; 12. Upright; 13. Support rod; 14. Clearance opening; 15. Support frame;

[0032] 101. Base frame; 102. First support rod section; 103. Second support rod section; 104. Sliding rod section; 105. First limiting block; 106. Second limiting block; 107. Locking rod; 108. Second connecting rod; 109. Support frame. Detailed Implementation

[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Those skilled in the art should understand that the embodiments described below are only some, not all, of the embodiments disclosed. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0034] The principles and spirit of this utility model will be explained in detail below with reference to several representative embodiments.

[0035] Embodiment 1 of a magnetic rail spike anchor bracket provided by this utility model:

[0036] like Figure 1 As shown, the magnetic rail spike anchor bracket includes a base frame 1, two spaced rail spike positioners 2, two spaced positioning rings 3, and a support frame 15 connecting the two rail spike positioners 2 and the two positioning rings 3.

[0037] In this embodiment, for ease of description, as follows: Figure 5 As shown, the length direction of sleeper 4 is defined as the left-right direction, and the width direction of sleeper 4 is defined as the front-back direction.

[0038] Specifically, such as Figure 2 and Figure 3 As shown, the base frame 1 is entirely made of round steel and includes two first connecting rods 9 and two second connecting rods 10. The two first connecting rods 9 are arranged parallel and spaced apart in the left-right direction, and the two second connecting rods 10 are vertically welded to the bottom of the two first connecting rods 9 and are arranged parallel and spaced apart in the front-back direction. The inner distance between the two second connecting rods 10 is greater than the bottom width of the rail groove 5 on the sleeper 4, and the outer distance between the two first connecting rods 9 is equal to the bottom length of the rail groove 5 on the sleeper 4. The two second connecting rods 10 are arranged at an angle, with the angle and direction of inclination the same as the angle and direction of inclination of the bottom of the rail groove 5. During installation, the base frame 1 is placed on the rail groove 5, with the two second connecting rods 10 close to the shoulder of the sleeper 4 and the two first connecting rods 9 close to the inclined surfaces on both sides of the bottom of the rail groove 5, thus ensuring the position of the threaded spikes on the sleeper 4.

[0039] like Figure 1 and Figure 2 As shown, two positioning rings 3 are arranged at intervals in the left-right direction. Each positioning ring 3 is connected to the corresponding first connecting rod 9 via a third connecting rod 11. The third connecting rod 11 is also made of round steel, and its two ends are welded to the positioning rings 3 and the first connecting rod 9. The bottom surface of the positioning ring 3 is an inclined surface that fits against the bottom of the rail bearing groove 5. However, the central hole of the positioning ring 3 is coaxial with the anchoring hole on the sleeper 4, and the axes of both extend in the vertical direction.

[0040] like Figure 2 As shown, the support frame 15 is located between two positioning rings 3 and is in an upright position. It includes two uprights 12 and two support rods 13. The two uprights 12 are parallel to each other and spaced apart in the left-right direction. The two support rods 13 are welded to the top and bottom ends of the two uprights 12, respectively. The two ends of the upper support rod 13 are connected to two rail spike positioners 2, and the two ends of the lower support rod 13 are connected to two positioning rings 3. Since the bottom of the rail bearing groove 5 has a certain slope, the lower support rod 13 is also inclined to match the slope.

[0041] like Figure 3 and Figure 4As shown, the road stud locator 2 includes an integrally formed arc-shaped upright plate and limiting upright plates connected to the left and right ends of the arc-shaped upright plate. The inner surface of the limiting upright plate is coplanar with the inner arc surface of the arc-shaped upright plate, thus forming a U-shaped positioning groove 6. The U-shaped positioning groove 6 is adapted to the upper end size of the road stud and is used to position the upper end of the road stud. The arc-shaped upright plate has a concave arc-shaped embedding groove formed by stamping, and an arc-shaped magnet 7 that can attract the road stud is embedded in the arc-shaped embedding groove. In this embodiment, the arc-shaped embedding groove is opened at the middle height position of the arc-shaped upright plate. In other embodiments, a long strip magnet 7 can also be used. In this case, the arc-shaped upright plate is provided with an embedding groove extending in the vertical direction, and the magnet 7 is embedded in a long strip shape.

[0042] The inner diameter of the positioning ring 3 is larger than the inner diameter of the arc-shaped upright plate, which makes the vertical cross-section of the outer side of the arc-shaped upright plate and the vertical cross-section of the outer side of the positioning ring 3 not coplanar. In order to ensure that the support frame 15 can connect the two road spike positioning devices 2 and the positioning ring 3, the two ends of the lower support rod 13 are respectively provided with clearance openings 14 to avoid the positioning ring 3. The lower support rod 13 has a pressing surface at the clearance opening 14 for pressing against the outer side and top surface of the positioning ring 3, and is connected to the positioning ring 3 by spot welding.

[0043] After fabrication, the distance between the two U-shaped positioning grooves 6 is equal to the distance between the two anchoring holes on the rail bearing groove 5, and the distance between the two positioning rings 3 is equal to the distance between the two anchoring holes on the rail bearing groove 5. Two rail spikes are vertically passed through the rail spike locator 2 and the positioning rings 3 respectively. The magnet 7 holds the rail spikes in place, and the protrusions on the rail spikes press against the lower end of the U-shaped limiting grooves. Anchoring agent is evenly injected into the anchoring holes using a grouting spoon. Then, the magnetic rail spike anchoring bracket of this invention, equipped with two rail spikes, is vertically placed in the rail bearing groove 5 of the sleeper 4. The rail spikes are vertically inserted into the anchoring holes from above, ensuring accurate positioning of the rail spikes.

[0044] The track spike positioner 2 and the positioning ring 3 work together to simultaneously position and constrain the upper and lower ends of the track spike, improving the positioning accuracy of the track spike and enabling the track spike to be accurately and stably installed on the sleeper 4, thereby improving the stability and safety of train operation.

[0045] Embodiment 2 of the magnetic rail spike anchor bracket provided by this utility model:

[0046] Its main difference from Example 1 is:

[0047] In Example 1, the dimensions of the base frame and the support frame are fixed.

[0048] In this embodiment, as Figure 6As shown, both the base frame 101 and the support frame 109 are telescopic frames that can be retracted and extended in the spaced direction of the two road spike positioners. Specifically, the second connecting rod 108 of the base frame 101 and the support rod of the support frame 109 are both telescopic rods.

[0049] The support rod includes a first support rod segment 102, a sliding rod segment 104, and a second support rod segment 103 arranged coaxially. The outer diameter of the first support rod segment 102 is equal to the outer diameter of the second support rod segment 103 and greater than the outer diameter of the sliding rod segment 104. The sliding rod segment 104 is fixed to the second support rod segment 103 and slides in cooperation with the first support rod segment 102. A locking and limiting structure is provided between the first support rod segment 102 and the sliding rod segment 104 of the support rod. The locking and limiting structure gives the sliding rod segment 104 a first locking position and a second locking position. When the sliding rod segment 104 is in the first locking position, the opposite ends of the first support rod segment 102 and the second support rod segment 103 are in a stop contact. When the sliding rod segment 104 is in the second locking position, the distance between the two U-shaped positioning grooves is equal to the distance between the two anchoring holes on the rail bearing groove.

[0050] In this embodiment, the locking and limiting structure includes a first limiting block 105, a second limiting block 106, and a locking rod 107. The first limiting block 105 and the second limiting block 106 are both fixed to the first support rod segment 102 and arranged at intervals. The locking rod 107 is T-shaped, including a horizontal segment and a vertical segment. The vertical segment is perpendicularly connected to the sliding rod segment 104 and slidably assembled with the first support rod segment 102. The first limiting block 105 and the second limiting block 106 are provided with coaxial through holes for the horizontal segment to pass through. External threads are provided at both ends of the horizontal segment. When the sliding rod segment 104 moves to the first locking position and the second locking position respectively, the sliding rod segment 104 can be locked by connecting the nut to the threaded horizontal segment.

[0051] Since the support frame 109 is a single unit, when one support rod is locked, the other support rod is also locked. Therefore, only the upper support rod needs to be equipped with a locking limit structure, while the lower support rod does not need to be equipped with a locking limit structure and can simply be a telescopic rod.

[0052] Similarly, the support frame 109 is connected to the two positioning rings to form a whole, and the positioning rings are connected to the base frame 101 through the third connecting rod to form a whole. Therefore, when the support frame 109 is retracted and extended, the base frame 101 retracts and extends synchronously with the support frame 109. When the size of the support frame 109 is fixed, the size of the base frame 101 is also fixed, and at this time, there is no need to set a locking limit structure on the base frame 101. That is, it is sufficient to set a locking limit structure on either the base frame 101 or the support frame 109. Since this embodiment sets a locking limit structure on the support frame 109, in other embodiments, a locking limit structure can also be set on the base frame 101.

[0053] In this embodiment, the base frame 101 and the support frame 109 can be retracted and unfolded, which facilitates transportation and storage and saves space during mass production.

[0054] Based on the above description in this specification, those skilled in the art will also understand that the following terms used, such as "upper," "lower," "front," "rear," "left," "right," "width," "horizontal," "top," "bottom," "inner," and "outer," are terms indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings of this specification. They are only for the purpose of facilitating the explanation of the present invention and simplifying the description, and do not explicitly or implicitly suggest that the device or element involved must have the specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as limitations on the present invention.

[0055] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A magnetic rail spike anchoring bracket, comprising a base frame and two spaced rail spike positioners, the base frame being placed in the rail bearing groove of a sleeper, the rail spike positioners being fixed relative to the base frame and having U-shaped positioning grooves adapted to the upper end size of the rail spike, the U-shaped positioning grooves being embedded with magnets for attracting the rail spikes, the distance between the two U-shaped positioning grooves being equal to the distance between two anchoring holes in the rail bearing groove, characterized in that... The base frame is provided with a positioning ring below each rail spike locator, which is adapted to the size of the lower end of the rail spike so that the rail spike can pass through. The distance between the two positioning rings is equal to the distance between the two anchoring holes on the rail bearing groove. The two positioning rings and the two rail spike locators are connected together by a support frame in an upright position.

2. The magnetic rail spike anchor bracket according to claim 1, characterized in that, The road stud locator includes an integrally formed arc-shaped upright plate and a limiting upright plate connected to both ends of the arc-shaped upright plate. The inner side of the limiting upright plate is coplanar with the inner arc surface of the arc-shaped upright plate. The arc-shaped upright plate has a concave arc-shaped embedding groove formed by stamping. The magnet is an arc-shaped magnet adapted to the arc-shaped embedding groove.

3. The magnetic rail spike anchor bracket according to claim 2, characterized in that, The arc-shaped embedding groove is located at the middle height of the arc-shaped vertical panel.

4. The magnetic rail spike anchor bracket according to claim 1, characterized in that, The bottom surface of the positioning ring is an inclined surface that fits into the bottom of the rail groove, and the central hole of the positioning ring is coaxial with the anchoring hole.

5. The magnetic rail spike anchor bracket according to any one of claims 1-4, characterized in that, Both the base frame and the support frame are telescopic frames that can be retracted and extended in the direction of the interval arrangement of the two road spike positioners.

6. The magnetic rail spike anchor bracket according to claim 5, characterized in that, The base frame includes two first connecting rods and two second connecting rods. The two first connecting rods are arranged parallel and spaced apart along the length of the sleeper. The two second connecting rods are perpendicularly connected to the bottom of the two first connecting rods and are arranged parallel and spaced apart along the width of the sleeper. The first connecting rods are used to contact the bottom of the rail groove. The support frame includes two uprights and two support rods. The two support rods are respectively connected to the top and bottom of the two uprights. The two ends of the upper support rod are respectively connected to two rail spike positioners, and the two ends of the lower support rod are respectively connected to two positioning rings. The side of the positioning ring facing away from the support rod is connected to the corresponding first connecting rod through a third connecting rod. Both the second connecting rods and the support rods are telescopic rods.

7. The magnetic rail spike anchor bracket according to claim 6, characterized in that, The support rod includes a first support rod segment, a sliding rod segment, and a second support rod segment arranged coaxially. The outer diameter of the first support rod segment is equal to the outer diameter of the second support rod segment and greater than the outer diameter of the sliding rod segment. The sliding rod segment is fixed to the second support rod segment and slides in cooperation with the first support rod segment. At least one of the support rods has a locking and limiting structure between the first support rod segment and the sliding rod segment of that support rod. The locking and limiting structure gives the sliding rod segment a first locking position and a second locking position. When the sliding rod segment is in the first locking position, the opposite ends of the first support rod segment and the second support rod segment are in a stop contact. When the sliding rod segment is in the second locking position, the distance between the two U-shaped positioning grooves is equal to the distance between the two anchoring holes on the rail bearing groove.

8. The magnetic rail spike anchor bracket according to claim 7, characterized in that, The locking and limiting structure includes a first limiting block, a second limiting block, and a locking rod. The first limiting block and the second limiting block are both fixed on the first support rod section and are arranged at intervals. The locking rod is T-shaped and includes a horizontal section and a vertical section. The vertical section is perpendicularly connected to the sliding rod section and is slidably assembled with the first support rod section. The first limiting block and the second limiting block are provided with coaxial through holes for the horizontal section to pass through. The two ends of the horizontal section are respectively provided with external threads.

9. The magnetic rail spike anchor bracket according to claim 2, characterized in that, The inner diameter of the positioning ring is larger than the inner diameter of the arc-shaped upright plate. The first and second support rod sections located on the lower side are provided with clearance openings for avoiding the positioning ring. The first and second support rod sections located on the lower side have pressing surfaces at the clearance openings for pressing against the side and top surfaces of the positioning ring.

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