A foldable portable design drawing holder

Abstract

This utility model relates to the field of drawing board holder technology and discloses a foldable portable design drawing holder, including a support plate and a carrying block. An L-shaped fixing plate is fitted inside the center of the L-shaped groove. Adjustment devices are provided on both sides of the center of the lower end face of the L-shaped fixing plate. Extension devices are provided on both sides of the center of the upper end face of the L-shaped fixing plate. Fixing devices are provided on one side of the center of the upper end face of each of the extension devices. Each extension device on one side includes multiple extension grooves, and extension rods are slidably connected to the center of each of the multiple extension grooves. A connecting rod is provided at one end of each of the multiple extension rods on one side of the L-shaped fixing plate. In this utility model, the extension devices allow for adjustment and adaptation to different drawing sizes, and the extension rods are flush with the L-shaped fixing plate, ensuring that the drawings do not wrinkle during placement and clamping, thus improving the flatness of the drawings.

Description

Technical Field

[0001] This utility model relates to the field of drawing board holder technology, and in particular to a foldable portable design drawing holder. Background Technology

[0002] To meet the needs of architects, engineers, designers, and other professionals to view, display, and discuss design drawings in different settings, design drawing holders are required. A design drawing holder is a device or tool used to store and secure design drawings, engineering drawings, and other related documents. Its main function is to ensure that the drawings are not damaged, lost, or moved during the work process, while providing convenient access, viewing, and organization methods.

[0003] Traditional design drawing holders are difficult to adjust to fit different drawing sizes, and their adjustment is not level with the original holder, which can easily cause wrinkles and damage to the drawings during clamping, thus reducing the flatness of the drawings. Therefore, those skilled in the art have provided a foldable portable design drawing holder to solve the problems mentioned in the background art. Utility Model Content

[0004] The purpose of this utility model is to address the shortcomings of existing technologies by proposing a foldable portable design drawing holder. Through an extension device, it can be adjusted and adapted to different drawing sizes, and the extension rod extends to be flush with the L-shaped fixing plate, ensuring that the drawings do not wrinkle during placement and clamping, thus improving the flatness of the drawing clamping.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a foldable portable design drawing holder, comprising a support plate and a carrying block, wherein the carrying block is disposed at the center of the rear end face of the support plate, an L-shaped groove is provided at the center of the upper end face of the support plate near the front end, and strip grooves are provided on both sides of the center of the upper end face of the support plate near the front end, an L-shaped fixing plate is fitted inside the center of the L-shaped groove, an adjustment device is provided at the center of the lower end face of the L-shaped fixing plate near both sides, an extension device is provided at the center of the upper end face of the L-shaped fixing plate near both sides, and a fixing device is provided at the center of the upper end face of each of the two extension devices near one side;

[0006] The extension device on one side includes multiple extension slots, which are arranged in a front-to-back manner at one end of the upper surface of the L-shaped fixing plate. An extension rod is slidably connected to the center of each extension slot. A connecting rod is provided at one end of each extension rod on one side of the L-shaped fixing plate and is slidably connected to the multiple extension slots.

[0007] Through the above technical solution, the extension rod slides inside the extension groove, which can drive the connecting rod to move, so that it can be adjusted and adapted according to different drawing sizes. It also achieves flatness between the extension rod and the L-shaped fixing plate, ensuring that the drawing does not wrinkle when placed and clamped, thus improving the flatness of the drawing clamping.

[0008] Furthermore, a sliding groove is provided at the center of the inner wall of the extension groove near the front end. The sliding groove passes through the L-shaped fixing plate and extends to the front end face of the L-shaped fixing plate. Magnetic strips are provided on both the upper and lower sides of the center side of the front end face of the L-shaped fixing plate. A magnetic block is provided at one end of the center of the front end face of the two magnetic strips. An operating block is provided at the center of the front end face of the magnetic block. A spring is provided at the center of the rear end face of the magnetic block. A connecting block is fixedly connected to the rear end of the spring. The connecting block is fixedly connected to the extension rod near the front end and slidably connected to the sliding groove. The magnetic block is magnetically connected to the two magnetic strips.

[0009] The above technical solution allows the extension rod to move by pulling the operating block to stretch its spring, thus releasing the magnetic connection between the magnetic block and the magnetic strip. The extension rod can then be adjusted by sliding the connecting block and the slide groove. Finally, the extension rod can be fixed by releasing the operating block to allow the spring to return to its original position.

[0010] Furthermore, the adjustment device on one side includes a first square groove, which is located on the lower end face of the L-shaped fixing plate. A support rod is sleeved at the front center of the first square groove, and a screw is provided at the front end of the center of the support rod. Multiple limiting grooves are arranged in a front-to-back pattern on one side of the lower inner wall of the L-shaped groove.

[0011] With the above technical solution, when the L-shaped fixing plate is unfolded, the support rod is rotated according to the required angle, and then the screw is rotated to adjust and extend it, so that the screw is sleeved inside the limiting groove, thus satisfying the support of the L-shaped fixing plate after it is unfolded.

[0012] Furthermore, the two sides of the support rod are rotatably connected to the two inner sidewalls of the first square groove near their respective ends via bearings, and the upper end face of the support rod is magnetically connected to the upper inner wall of the first square groove near its front end.

[0013] The above technical solution achieves the rotational requirements of the support rod by means of a bearing rotatable connection between the support rod and the first square groove, and prevents accidental detachment when not in use by means of a magnetic connection between the support rod and the first square groove.

[0014] Furthermore, the fixing device on one side includes a fixing block, which is located at the center of the upper end face of the connecting rod. The center of the lower end face of the fixing block is provided with an inclined groove at one end. The center of the lower end face of the fixing block is provided with a second square groove. A roller is provided at the lower center of the second square groove. The roller is rotatably connected to the front and rear inner walls of the second square groove through bearings. A first magnetic block is embedded at one end of the center of the upper end face of the extension groove.

[0015] With the above technical solution, when it is necessary to fix the drawing, the end of the drawing is inserted into the gap between the fixing block and the connecting rod along the inclined groove, and then the drawing can be moved smoothly by the rotation of the roller, so as to avoid obstruction and cause wrinkles in the drawing, thus achieving the initial clamping of the drawing.

[0016] Furthermore, a third-dimensional groove is provided at one end of the center of the lower end face of the fixing block, and a threaded hole is provided at the center of the inner wall of the third-dimensional groove. The threaded hole passes through the lower end face of the fixing block and extends to the upper end face of the fixing block. A bolt is provided at one side of the center of the upper end face of the fixing block, and the end of the bolt is threaded into the bolt. A second magnetic block is provided at the center of the inner wall of the third-dimensional groove. The second magnetic block and the end of the bolt are rotatably connected by a bearing, and the second magnetic block and the first magnetic block are magnetically attracted to each other.

[0017] The above technical solution uses a rotating bolt to move the second magnetic block, which allows the second magnetic block to be magnetically attracted to the first magnetic block, thus achieving secondary clamping of the drawing and further enhancing the clamping force. This ensures that the drawing will not slip, thereby enhancing the clamping effect and ensuring the stability of the drawing on the fixed frame.

[0018] Furthermore, the horizontal groove of the L-shaped groove passes through the upper surface of the support plate and extends into the interior of the support plate, and the vertical groove passes through the upper surface of the support plate and extends into the lower surface of the support plate. The vertical groove of the L-shaped groove and the vertical plate of the L-shaped fixing plate are rotatably connected by a rotating shaft. The center of the lower inner wall of the L-shaped groove near the rear end is magnetically connected to the center of the lower end face of the L-shaped fixing plate near the rear end.

[0019] Through the above technical solution, the horizontal and vertical plates of the L-shaped groove are connected, and the L-shaped groove and the L-shaped fixing plate are fitted together. The L-shaped groove and the L-shaped fixing plate are rotatably connected by a rotating shaft, which allows the L-shaped fixing plate to be adjusted in rotation angle. The strip groove allows the L-shaped fixing plate to rotate smoothly. The magnetic connection between the L-shaped groove and the L-shaped fixing plate ensures that the L-shaped fixing plate is fixed during recycling, preventing accidental detachment and affecting carrying.

[0020] This utility model has the following beneficial effects:

[0021] 1. In this utility model, when the foldable portable design drawing holder is used, the extension rod slides inside the extension groove, which can drive the connecting rod to move, so that it can be adjusted and adapted according to different drawing sizes. It also achieves that the extension rod extends and is level with the L-shaped fixing plate, ensuring that the drawing does not wrinkle when placed and clamped, thus improving the flatness of the drawing clamping.

[0022] 2. In this utility model, when it is necessary to fix the drawing, the end of the drawing is inserted into the gap between the fixing block and the connecting rod along the inclined groove, and then the drawing can be moved smoothly by the rotation of the roller, avoiding obstruction that would cause wrinkles in the drawing, thus achieving initial clamping of the drawing. Then, the second magnetic block is moved by rotating the bolt, so that the magnetic attraction between the second magnetic block and the first magnetic block is satisfied, thus achieving secondary clamping of the drawing, further enhancing the clamping force, ensuring that the drawing will not slip, thereby enhancing the clamping effect and ensuring the stability of the drawing on the fixing frame. Attached Figure Description

[0023] Figure 1 This is a perspective view of a foldable portable design drawing holder proposed in this utility model;

[0024] Figure 2 This is a three-dimensional sectional view of a foldable portable design drawing holder proposed in this utility model;

[0025] Figure 3 This is a three-dimensional unfolded view of a foldable portable design drawing holder proposed in this utility model;

[0026] Figure 4 This is a perspective view of a foldable portable design drawing fixing bracket connecting block proposed in this utility model;

[0027] Figure 5 for Figure 1 Enlarged view of point A in the middle;

[0028] Figure 6 for Figure 2 Enlarged diagram of point B in the middle.

[0029] Legend:

[0030] 1. Support plate; 2. Handle block; 3. L-shaped groove; 4. Strip groove; 5. L-shaped fixing plate; 6. Adjustment device; 601. First square groove; 602. Support rod; 603. Screw; 604. Limiting groove; 7. Extension device; 701. Extension groove; 702. Extension rod; 703. Connecting rod; 704. Slide groove; 705. Magnetic strip; 706. Magnetic block; 707. Operating block; 708. Spring; 709. Connecting block; 8. Fixing device; 801. Fixing block; 802. Inclined groove; 803. Second square groove; 804. Roller; 805. First magnetic block; 806. Third square groove; 807. Threaded hole; 808. Bolt; 809. Second magnetic block. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] Reference Figure 1-6 This utility model provides an embodiment of a foldable portable design drawing holder, comprising a support plate 1 and a carrying block 2. The carrying block 2 is located at the center of the rear end face of the support plate 1. An L-shaped groove 3 is provided at the center of the upper end face of the support plate 1 near the front end. Strip grooves 4 are provided on both sides of the center of the upper end face of the support plate 1 near the front end. An L-shaped fixing plate 5 is fitted inside the center of the L-shaped groove 3. Adjustment devices 6 are provided at the center of the lower end face of the L-shaped fixing plate 5 near both sides. Extension devices 7 are provided at the center of the upper end face of the L-shaped fixing plate 5 near both sides. Fixing devices 8 are provided on one side of the center of the upper end face of the two extension devices 7. The extension devices 7 allow for adjustment and adaptation according to different drawing sizes, and ensure that the extension rod 702 is level with the L-shaped fixing plate 5, preventing wrinkles from affecting the viewing of the drawings during placement and clamping, thereby improving the flatness of the drawings.

[0033] The adjustment device 6 on one side includes a first square groove 601, which is located on the lower end face of the L-shaped fixing plate 5. A support rod 602 is sleeved at the front center of the first square groove 601. A screw 603 is provided at the front center of the support rod 602. Multiple limiting grooves 604 are arranged in a front-to-back pattern on one side of the lower inner wall of the L-shaped groove 3. When the L-shaped fixing plate 5 is unfolded, the support rod 602 is rotated according to the required angle, and the screw 603 is rotated to adjust and extend it. This allows the screw 603 to be sleeved inside the limiting groove 604, thus providing support for the L-shaped fixing plate 5 after it is unfolded.

[0034] The two sides of the support rod 602 are rotatably connected to the two inner side walls of the first square groove 601 near their respective ends via bearings. The upper end face of the support rod 602 is magnetically connected to the upper inner wall of the first square groove 601 near its front end. The rotatable connection between the support rod 602 and the first square groove 601 via bearings satisfies the rotational requirements of the support rod 602. The magnetic connection between the support rod 602 and the first square groove 601 prevents accidental detachment when not in use.

[0035] The side-fixing device 8 includes a fixing block 801, which is located at the center of the upper end face of the connecting rod 703. The center of the lower end face of the fixing block 801 is provided with a sloping groove 802 and a second square groove 803. A roller 804 is provided at the lower center of the second square groove 803. The roller 804 is rotatably connected to the front and rear inner walls of the second square groove 803 through bearings. A first magnetic block 805 is embedded at the center of the upper end face of the extension groove 701. When it is necessary to fix the drawing, the end of the drawing is inserted into the gap between the fixing block 801 and the connecting rod 703 along the sloping groove 802, and then the roller 804 is rotated to allow the drawing to move smoothly, avoiding obstruction that could cause wrinkles in the drawing, thus achieving initial clamping of the drawing.

[0036] A third-dimensional groove 806 is provided at one end of the lower end face of the fixing block 801. A threaded hole 807 is provided at the center of the inner wall of the third-dimensional groove 806, passing through the lower end face of the fixing block 801 and extending to the upper end face of the fixing block 801. A bolt 808 is provided at one side of the center of the upper end face of the fixing block 801, with the end of the bolt 808 threadedly fitted inside the bolt 808. A second magnetic block 809 is provided at the center of the inner wall of the third-dimensional groove 806. The second magnetic block 809 is rotatably connected to the end of the bolt 808 through a bearing. The second magnetic block 809 and the first magnetic block 805 are magnetically attracted to each other. By rotating the bolt 808, the second magnetic block 809 is moved, satisfying the magnetic attraction between the second magnetic block 809 and the first magnetic block 805, realizing secondary clamping of the drawing, further enhancing the clamping force, ensuring that the drawing will not slip, thereby enhancing the clamping effect and ensuring the stability of the drawing on the fixing frame.

[0037] The horizontal groove of the L-shaped groove 3 passes through the upper end face of the support plate 1 and extends into the interior of the support plate 1, while the vertical groove passes through the upper end face of the support plate 1 and extends into the lower end face of the support plate 1. The vertical groove of the L-shaped groove 3 and the vertical plate of the L-shaped fixing plate 5 are rotatably connected by a pivot. The center of the lower inner wall of the L-shaped groove 3 near the rear end is magnetically connected to the center of the lower end face of the L-shaped fixing plate 5 near the rear end. Through the passage of the horizontal and vertical plates of the L-shaped groove 3, and through the fitting between the L-shaped groove 3 and the L-shaped fixing plate 5, and through the rotatable connection between the L-shaped groove 3 and the L-shaped fixing plate 5 by a pivot, the L-shaped fixing plate 5 can be rotated at an adjustable angle. The strip groove 4 allows the L-shaped fixing plate 5 to rotate smoothly. The magnetic connection between the L-shaped groove 3 and the L-shaped fixing plate 5 ensures that the L-shaped fixing plate 5 is fixed during recycling, preventing accidental detachment and affecting carrying.

[0038] like Figure 3 , 4 As shown in Figure 5, the one-sided extension device 7 includes multiple extension slots 701. The multiple extension slots 701 are arranged in a front-to-back manner at one end of the upper surface of the L-shaped fixing plate 5. An extension rod 702 is slidably connected to the center of each of the multiple extension slots 701. A connecting rod 703 is provided at one end of each of the multiple extension rods 702 on one side of the L-shaped fixing plate 5, and is slidably connected to the multiple extension slots 701. By sliding the extension rod 702 inside the extension slot 701, the connecting rod 703 can be moved, so that it can be adjusted and adapted according to different drawing sizes. It also ensures that the extension rod 702 extends and is level with the L-shaped fixing plate 5, ensuring that the drawing does not wrinkle when placed and clamped, thus improving the flatness of the drawing clamping.

[0039] A sliding groove 704 is provided at the center of the inner wall of the front extension groove 701. The sliding groove 704 passes through the L-shaped fixing plate 5 and extends to the front face of the L-shaped fixing plate 5. Magnetic strips 705 are provided on the upper and lower sides of the center of the front face of the L-shaped fixing plate 5. A magnetic block 706 is provided at one end of the center of the front face of the two magnetic strips 705. An operating block 707 is provided at the center of the front face of the magnetic block 706. A spring 708 is provided at the center of the rear face of the magnetic block 706. A connecting block 709 is fixedly connected to the rear end of the spring 708. The connecting block 709 is fixedly connected to the front extension rod 702. The magnetic block 706 is slidably connected to the slide groove 704, and the magnetic block 706 is magnetically connected to the two magnetic strips 705. By pulling the operating block 707, the spring 708 is stretched, which satisfies the magnetic connection between the magnetic block 706 and the magnetic strips 705. Then, the connecting block 709 is slidably connected to the slide groove 704, which satisfies the extension movement of the extension rod 702 and achieves the adjustment effect. Then, by releasing the operating block 707, the spring 708 is rebounded, which satisfies the magnetic connection between the magnetic block 706 and the magnetic strips 705 and achieves the fixation of the extension rod 702.

[0040] Working principle: When using the foldable portable design drawing holder, the horizontal and vertical plates of the L-shaped groove 3 pass through, and the L-shaped groove 3 is fitted with the L-shaped fixing plate 5. The L-shaped groove 3 and the L-shaped fixing plate 5 are rotatably connected by a pivot, allowing the L-shaped fixing plate 5 to rotate at an adjustable angle. The strip groove 4 allows the L-shaped fixing plate 5 to rotate smoothly. Finally, the magnetic connection between the L-shaped groove 3 and the L-shaped fixing plate 5 ensures that the L-shaped fixing plate 5 is secured during recycling, preventing accidental detachment. When the L-shaped fixing plate 5 is unfolded, the support rod 602 is rotated according to the required angle, and the screw 603 is rotated to adjust and extend it. This allows the screw 603 to be fitted inside the limiting groove 604, thus providing support for the unfolded L-shaped fixing plate 5. The support rod 602 is rotatably connected to the first square groove 601 via a bearing, which satisfies the rotation requirements of the support rod 602. The support rod 602 is also magnetically connected to the first square groove 601, which prevents accidental detachment when not in use.

[0041] By sliding the extension rod 702 inside the extension groove 701, the connecting rod 703 can be moved, allowing it to be adjusted and adapted to different drawing sizes. This also ensures that the extension rod 702 extends to be flush with the L-shaped fixing plate 5, preventing wrinkles from affecting viewing when the drawing is placed and clamped, thus improving the flatness of the drawing clamping. Pulling the operating block 707 stretches the spring 708, releasing the magnetic connection between the magnetic block 706 and the magnetic strip 705. The connecting block 709 then slides through the groove 704, allowing the extension rod 702 to extend and move, achieving the adjustment effect. Releasing the operating block 707 causes the spring 708 to return, restoring the magnetic connection between the magnetic block 706 and the magnetic strip 705, thus fixing the extension rod 702.

[0042] When it is necessary to fix the drawing, the end of the drawing is inserted into the gap between the fixing block 801 and the connecting rod 703 along the inclined groove 802, and then the roller 804 is rotated to allow the drawing to move smoothly, avoiding obstruction that could cause wrinkles. This achieves initial clamping of the drawing. Then, the rotating bolt 808 drives the second magnetic block 809 to move, satisfying the magnetic attraction between the second magnetic block 809 and the first magnetic block 805, achieving secondary clamping of the drawing, further enhancing the clamping force, ensuring that the drawing will not slip, thereby enhancing the clamping effect and ensuring the stability of the drawing on the fixing frame.

[0043] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A foldable portable design drawing holder, comprising a support plate (1) and a carrying block (2), wherein the carrying block (2) is disposed at the center of the rear end face of the support plate (1), characterized in that: The support plate (1) has an L-shaped groove (3) at the center of the upper end face near the front end, and strip grooves (4) are provided on both sides of the center of the upper end face near the front end. An L-shaped fixing plate (5) is fitted inside the center of the L-shaped groove (3). An adjustment device (6) is provided on both sides of the center of the lower end face of the L-shaped fixing plate (5). An extension device (7) is provided on both sides of the center of the upper end face of the L-shaped fixing plate (5). A fixing device (8) is provided on one side of the center of the upper end face of the two extension devices (7). The extension device (7) on one side includes multiple extension slots (701). The multiple extension slots (701) are arranged in a front-to-back manner at one end of the upper surface of the L-shaped fixing plate (5). An extension rod (702) is slidably connected to the center of each of the multiple extension slots (701). A connecting rod (703) is provided at one end of the multiple extension rods (702) on one side of the L-shaped fixing plate (5), and is slidably connected to the multiple extension slots (701).

2. The folding portable design sheet holder of claim 1, wherein: A sliding groove (704) is provided at the center of the inner wall of the extension groove (701) at the front end. The sliding groove (704) passes through the L-shaped fixing plate (5) and extends to the front end face of the L-shaped fixing plate (5). Magnetic strips (705) are provided on the upper and lower sides of the center side of the front end face of the L-shaped fixing plate (5). Magnetic blocks (706) are provided at one end of the center of the front end face of the two magnetic strips (705). An operating block (707) is provided at the center of the front end face of the magnetic block (706). A spring (708) is provided at the center of the rear end face of the magnetic block (706). A connecting block (709) is fixedly connected to the rear end of the spring (708). The connecting block (709) is fixedly connected to the extension rod (702) at the front end and slidably connected to the sliding groove (704). The magnetic block (706) is magnetically connected to the two magnetic strips (705).

3. The folding portable design sheet holder of claim 1, wherein: The adjustment device (6) on one side includes a first square groove (601), which is located on the lower end face of the L-shaped fixing plate (5). A support rod (602) is sleeved at the front of the center of the first square groove (601), and a screw (603) is provided at the front end of the center of the support rod (602). Multiple limiting grooves (604) are arranged in a front-to-back pattern on the rear side of the lower inner wall of the L-shaped groove (3).

4. The folding portable design sheet holder of claim 3, wherein: The two sides of the support rod (602) are rotatably connected to the two inner side walls of the first square groove (601) near the center of one end by bearings. The upper end face of the support rod (602) is connected to the upper inner wall of the first square groove (601) near the center of the front end by magnetic attraction.

5. The folding portable design sheet holder of claim 1, wherein: The fixing device (8) on one side includes a fixing block (801), which is located at the center of the upper end face of the connecting rod (703). The fixing block (801) has a slanted groove (802) at one end of the center of the lower end face of the fixing block (801). The fixing block (801) has a second square groove (803) at the center of the lower end face of the fixing block (801). The roller (804) is located at the lower center of the second square groove (803). The roller (804) is rotatably connected to the front and rear inner walls of the second square groove (803) through bearings. The first magnetic block (805) is embedded at one end of the center of the upper end face of the extension groove (701).

6. A folding portable design sheet holder according to claim 5, wherein: A third-dimensional groove (806) is provided at one end of the lower end face of the fixing block (801). A threaded hole (807) is provided at the center of the inner wall of the third-dimensional groove (806). The threaded hole (807) passes through the lower end face of the fixing block (801) and extends to the upper end face of the fixing block (801). A bolt (808) is provided at one side of the center of the upper end face of the fixing block (801). The end of the bolt (808) is threaded and sleeved inside the bolt (808). A second magnetic block (809) is provided at the center of the inner wall of the third-dimensional groove (806). The second magnetic block (809) and the end of the bolt (808) are rotatably connected by a bearing. The second magnetic block (809) and the first magnetic block (805) are magnetically attracted to each other.

7. The folding portable design sheet holder of claim 1, wherein: The horizontal groove of the L-shaped groove (3) passes through the upper end face of the support plate (1) and extends to the interior of the support plate (1), and the vertical groove passes through the upper end face of the support plate (1) and extends to the lower end face of the support plate (1). The vertical groove of the L-shaped groove (3) and the vertical plate of the L-shaped fixing plate (5) are rotatably connected by a rotating shaft. The center of the lower inner wall of the L-shaped groove (3) near the rear end is magnetically connected to the center of the lower end face of the L-shaped fixing plate (5) near the rear end.

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