Limiting structure of stacked movable blades

Abstract

The utility model discloses a limiting structure for stacked movable blades, which relates to the field of plate folding machine equipment and comprises a positioning frame and a plurality of blades. Limiting strips are fixedly installed on the left side and the right side of the positioning frame, a plurality of protruding blocks are formed on the outer sides of the limiting strips, the blades comprise the first blades and the second blades, the two ends of the bottom sides of the first blades are installed on the protruding blocks in a clamped mode respectively, and the two ends of the bottom sides of the second blades are installed on the limiting strips in a clamped mode respectively. When the PCB folding machine is used, a PCB to be folded is conveyed to the position above the blades, the blades at the corresponding positions are driven to ascend and descend in a rolling wheel sliding mode, pressing of high-elastic materials on the top is matched, the PCB is stably pressed on the blades, and due to the fact that the distance between every two adjacent blades is small, and the blades are very thin, the PCB can be folded stably. Therefore, when the blade ascends and descends, the board folding action can be simulated, the PCB material can be quickly broken, and the board folding action can be completed at a time even if a plurality of PCBs are arranged on the PCB material.

Description

Technical Field

[0001] This utility model relates to the field of folding machine equipment, and in particular to a limiting structure for stacked movable blades. Background Technology

[0002] A PCB (Printed Circuit Board) is the carrier for the electrical connections of electronic components. In industry, to achieve mass production of PCBs, multiple PCBs are typically fabricated on a single board. A PCB depaneling machine usually refers to a PCB depaneling machine, also known as a circuit board depaneling machine. Depaneling machines are widely used in the electronics manufacturing industry. Because traditional manual PCB bending methods generate strong stress, severely impacting product quality, manual bending has been largely replaced by machine depaneling.

[0003] The common solution is to use a PCB depaneling machine to mill each PCB. To prevent the PCB from shifting or warping during milling and to ensure the quality of PCB processing, a conveyor line is used to transport the PCB to be milled to the positioning fixture. The positioning fixture is then used to position the PCB before milling. After milling, the PCB is output using a conveyor line.

[0004] For example, an existing patent (publication number: CN117381877A, publication date: 2024.01.12) discloses a PCB board slitting and splitting machine. Under the squeezing action of the top plate and the limiting pulley, the PCB board can be fixed above the material conveying plate. After the motor starts, the reciprocating screw can drive the material conveying plate to move back and forth along the slide rail, so as to achieve more precise and automated cutting of the PCB board.

[0005] In the above solution, only one line can be cut at a time. For products that are made of multiple PCB boards on one board, the cutting efficiency is very low. Although the traditional manual board bending solution is more efficient, it will affect the quality of the product. Therefore, it is necessary to design a mechanism that uses mechanical board bending. Utility Model Content

[0006] To overcome the shortcomings mentioned above, this utility model provides a technical solution that can solve the above problems.

[0007] A limiting structure for stacked movable blades includes a positioning frame and several blades; limiting strips are fixedly installed on both the left and right sides of the positioning frame, and several protrusions are formed on the outer side of the limiting strips; the several blades include several first blades and several second blades, with the two ends of the bottom side of the first blades respectively snapped onto the protrusions, and the two ends of the bottom side of the second blades respectively snapped onto the limiting strips.

[0008] Furthermore: both the first blade and the second blade are divided into arrays, and the array of first blades and array of second blades are arranged in an alternating and overlapping manner.

[0009] Furthermore: the number of the first blades in each group is equal to the number of the second blades in each group.

[0010] Furthermore: both ends of the bottom side of the first blade are formed with first barbs, which are snapped onto the protrusion; both ends of the bottom side of the second blade are formed with second barbs, which are snapped onto the limiting strip.

[0011] Furthermore, several of the aforementioned bumps are arranged in an array at equal intervals.

[0012] Furthermore: the positioning frame includes a positioning base plate and two side limiting plates. The two side limiting plates are fixedly installed on the left and right ends of the positioning base plate, respectively. The two side limiting plates are symmetrically arranged with each other, and the limiting strips are fixedly installed on the outer side of the side limiting plates one by one.

[0013] Furthermore, a height adjustment edge is installed on the outer side of the side limiting plate, and the two ends of the bottom sides of the first blade and the second blade respectively abut against the height adjustment edge.

[0014] Furthermore: a first side cover is fixedly installed on the outer side of the height adjustment edge, and the first blade and the second blade are both installed between the first side covers on the left and right sides with a clearance fit.

[0015] Furthermore: two limiting top edges are fixedly installed between the two side limiting plates, and a number of first blades and a number of second blades are installed between the two limiting top edges with a gap fit.

[0016] Furthermore: a second side cover is fixedly installed on the outer side of the limiting top edge, and the positioning frame is located between the two second side covers.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] 1. In use, the PCB board material to be folded is fed above several blades. The corresponding blades are raised and lowered by the sliding of the rollers. Combined with the pressure of the high elastic material on the top, the board material is stably pressed on the blades. Since the distance between two adjacent blades is very small and the blades are very thin, the movement of the blades can simulate the action of folding the board, so as to quickly fold the PCB board material along the cutting line. Even if there are multiple PCB boards on the PCB board material, the folding action can be completed in one go.

[0019] 2. Protrusions are set on the limiting strip. The structure of the limiting strip allows the second blade and the first blade to be staggered and locked onto the limiting strip and the protrusions on the limiting strip, thereby ensuring the stable lifting and lowering movement of the first blade and the second blade after stacking, without tilting.

[0020] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of this utility model;

[0023] Figure 2 This is a schematic diagram of a structure that uses a highly elastic material to press down the blade to fold the plate.

[0024] Figure 3 This is a structural schematic diagram of a single side limiting plate;

[0025] Figure 4 This is a structural diagram of two side limiting plates;

[0026] Figure 5 This is an exploded structural diagram of the present invention;

[0027] Figure 6 yes Figure 5 A magnified structural diagram at point A.

[0028] The diagram shows: 01, positioning base plate; 02, lead screw conveying mechanism; 0201, drive motor; 0202, coupling; 0203, lead screw shaft; 0204, lead screw drive block; 03, roller assembly; 0301, sliding platform; 0302, roller bracket; 0303, support roller; 04, side limiting plate; 05, first blade; 06, second blade; 07, limiting strip; 08, first barb; 09, the... Two barbs; 010, protrusion; 011, height adjustment edge; 012, positioning post; 013, vertical thread; 014, screw; 015, internal hexagonal groove; 016, vertical adjustment groove; 017, locking bolt; 018, guide rail; 019, sliding block; 020, limiting top edge; 021, second side cover; 022, high elastic material; 023, motor base; 024, lead screw support base; 025, first side cover. Detailed Implementation

[0029] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0030] The components of the present invention embodiments described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0031] Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0032] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0034] Example 1, as Figure 1-6 As shown, the present invention provides a limiting structure for a stacked movable blade, comprising a positioning frame and several blades; limiting strips 07 are fixedly installed on both the left and right sides of the positioning frame, and several protrusions 010 are formed on the outer side of the limiting strips 07; the several blades include several first blades 05 and several second blades 06; the two ends of the bottom side of the first blades 05 are respectively snapped onto the protrusions 010, and the two ends of the bottom side of the second blades 06 are respectively snapped onto the limiting strips 07;

[0035] The principle is as follows: A protrusion 010 is set on the limiting strip 07. By utilizing the structure of the limiting strip 07, the second blade 06 and the first blade 05 can be staggered and locked onto the limiting strip 07 and the protrusion 010 of the limiting strip 07. This ensures the stable lifting and lowering movement of the first blade 05 and the second blade 06 after stacking, without tilting. In actual use, the PCB board material to be bent is transported above several blades. The corresponding blades are lifted and lowered by the sliding of rollers. With the pressure of the high-elastic material 022 at the top, the board material is stably pressed onto the blades. Since the distance between two adjacent blades is very small and the blades are very thin, the lifting and lowering of the blades can simulate the action of bending the board, realizing the rapid bending of the PCB board material along the cutting line. Even if there are multiple PCB boards on the PCB board material, the bending action can be completed in one go.

[0036] Furthermore: the first blade 05 and the second blade 06 are both divided into arrays, and the array of first blade 05 and array of second blade 06 are arranged in an alternating layered manner; this can realize the positioning of the first blade 05 and the second blade 06 after they are stacked, so that the first blade 05 and the second blade 06 can be arranged separately on the positioning frame, and there will be no tilting when they are raised and lowered.

[0037] Furthermore, each group of first blades 05 and each group of second blades 06 are provided with multiple blades arranged in a stacked manner; the stacked arrangement of multiple blades allows the first blades 05 and second blades 06 to remain in a vertical position, ensuring that the first blades 05 and second blades 06 can move up and down without tilting.

[0038] Furthermore, the number of first blades 05 in each group is equal to the number of second blades 06 in each group, which ensures the stable lifting and lowering movement of the first blades 05 and the second blades 06.

[0039] Furthermore: both ends of the bottom side of the first blade 05 are formed with first barbs 08, which are snapped onto the protrusion 010; both ends of the bottom side of the second blade 06 are formed with second barbs 09, which are snapped onto the limiting strip 07; the first barbs 08 and the second barbs 09 can be used to snap onto the protrusion 010 and the limiting strip 07 respectively, thereby achieving segmented limiting and ensuring that the first blade 05 and the second blade 06 will not tilt.

[0040] Furthermore, several of the aforementioned bumps 010 are arranged in an array at equal intervals.

[0041] In this invention, the primary function of the limiting strip 07 and the first blade 05 and second blade 06 is to segment and separate the blades. A certain gap must be maintained between adjacent blades for the first blade 05 and second blade 06 to slide smoothly up and down. Without this segmentation, the gap between adjacent blades is difficult to control. A large gap will cause the blade to tilt to one side, while a small gap will increase friction, resulting in uneven up-and-down movement. Furthermore, as the blades rub against each other, wear will occur, and the gap will widen over time. This widening gap will cause the blade gaps to accumulate, leading to the blade tilting to one side. Therefore, additional blades must be added to fill the gaps and prevent the blades from tilting. This invention utilizes segmented protrusions 010 to effectively control the blade gaps, preventing excessive accumulation. This allows for wider gaps between blades while ensuring smooth up-and-down movement, and also solves the problem of increased blade wear leading to larger gaps and the need for additional blades.

[0042] Furthermore: the positioning frame includes a positioning base plate 01 and two side limiting plates 04. The two side limiting plates 04 are respectively fixedly installed on the left and right ends of the positioning base plate 01. The two side limiting plates 04 are symmetrically arranged with each other. The limiting strips 07 are fixedly installed on the outer side of the side limiting plates 04 in a one-to-one correspondence. This can realize the stable installation of the first blade 05 and the second blade 06 on the positioning frame.

[0043] Furthermore: a height adjustment edge 011 is installed on the outer side of the side limiting plate 04, and the two ends of the bottom sides of the first blade 05 and the second blade 06 respectively abut against the height adjustment edge 011; the height adjustment edge 011 can be used to adjust the distance between the lifting and lowering movements of the first blade 05 and the second blade 06.

[0044] Furthermore: A first side cover 025 is fixedly installed on the outer side of the height adjustment edge 011, and the first blade 05 and the second blade 06 are both fitted with a clearance between the first side covers 025 on the left and right sides; the setting of the first side cover 025 can ensure that the first blade 05 and the second blade 06 will not tilt left or right, thereby ensuring their stable lifting and lowering.

[0045] Furthermore: Two limiting top edges 020 are fixedly installed between the two side limiting plates 04, and a number of first blades 05 and a number of second blades 06 are installed between the two limiting top edges 020 with a gap fit; the setting of the limiting top edges 020 can ensure that the first blades 05 and second blades 06 on the front and rear sides will not tilt forward or backward, thereby ensuring their stable lifting and lowering.

[0046] Furthermore: a second side cover 021 is fixedly installed on the outer side of the limiting top edge 020, and the positioning frame is located between the two second side covers 021; the second side cover 021 can play a protective role.

[0047] Example 2, as Figure 1-6 As shown, the present invention provides a limiting structure for a stacked movable blade, comprising a positioning base plate 01, a lead screw conveying mechanism 02, a roller assembly 03, two side limiting plates 04, and multiple blades.

[0048] The plurality of blades includes a plurality of first blades 05 and a plurality of second blades 06;

[0049] The lead screw conveying mechanism 02 is fixedly installed on the positioning base plate 01. The lead screw conveying mechanism 02 drives the roller group 03 to move back and forth. The two side limiting plates 04 are fixedly installed on the left and right ends of the upper side of the positioning base plate 01, and the lead screw conveying mechanism 02 is located between the two side limiting plates 04.

[0050] The two side limiting plates 04 are symmetrically arranged to each other. A limiting strip 07 is fixedly installed on the top edge of the outer side of the side limiting plate 04. The two ends of the bottom sides of the multiple first blades 05 and multiple second blades 06 are respectively snapped onto the limiting strips 07 of the two side limiting plates 04.

[0051] When the roller assembly 03 moves, it causes the first blade 05 and the second blade 06 to be lifted upwards.

[0052] The principle is as follows: The sheet metal to be separated is conveyed piece by piece by a conveyor and placed above the separating machine module. A high-elasticity material 022 (such as pearl cotton) is then used to press down on the top and side surfaces of the sheet metal. At this point, the bottom surface of the sheet metal will press against multiple first blades 05 and multiple second blades 06. The separating lines on the sheet metal are parallel to the first blades 05 and second blades 06. Then, the screw conveyor mechanism 02 is activated, driving the roller assembly 03 to move back and forth. As the roller assembly 03 moves back and forth, it lifts the corresponding first blades 05 and second blades 06. When several first blades 05 and second blades 06 are raised, the pressing action with the upper high-elastic material 022 simulates a repeated manual folding action, allowing multiple PCBs on the board to separate from each other, achieving rapid board separation. Even if there are multiple PCBs on the board, the separation can be completed in one go. Compared with the traditional cutting method, the separation efficiency of this utility model is higher. Moreover, the separation is carried out by mechanical equipment, which can ensure the force and angle when folding each PCB, and at the same time, no static electricity is generated, which can ensure the quality of the PCB after rapid folding.

[0053] Furthermore: the first blade 05 has first barbs 08 formed at both ends of its bottom side, and the second blade 06 has second barbs 09 formed at both ends of its bottom side. The outer side of the limiting strip 07 has protrusions 010 arranged in an equidistant array. The first barbs 08 are snapped onto the protrusions 010, and the second barbs 09 are snapped onto the limiting strip 07. The protrusions 010 provide precise positioning for multiple stacked first blades 05 and multiple stacked second blades 06, allowing them to rise or fall stably. The top sides of the first blades 05 and the second blades 06 have no cutting edges, thus effectively lifting the board material and simulating the action of bending the board. As the roller group 03 moves back and forth, even if the board material contains multiple PCB boards, it can be quickly separated.

[0054] Furthermore: the thickness of the limiting strip 07 is the same as the thickness of the protrusion 010, and the width of the first barb 08 and the second barb 09 is greater than the thickness of the limiting strip 07; this makes the installation of the first blade 05 and the second blade 06 more stable and secure, ensuring that the first blade 05 and the second blade 06 will not tilt when they move up and down, thereby ensuring the quality of the plate separation.

[0055] In this utility model, the main function of the limiting strip 07 and the first blade 05 and second blade 06 is to segment and separate the blades. Because a certain gap must be left between adjacent blades, the first blade 05 and the second blade 06 can slide smoothly up and down. If they are not segmented, it is difficult to control the gap between adjacent blades. If the gap is large, the blade will fall to one side. If the gap is small, the friction between the blades will increase, resulting in the blades not moving smoothly up and down. Furthermore, as the blades continue to rub against each other, wear will occur, and the gap will increase with the use time. The increased gap will cause the blade gaps to accumulate and stack together, causing the blades to fall to one side. Therefore, it is necessary to continuously add blades to fill the gaps to ensure that the blades do not fall over. This application uses the segmented separating protrusion 010 to effectively control the blade gaps and prevent the accumulated gaps between the blades from becoming too large. This can both widen the gaps between the blades and ensure smooth up and down movement of the blades. It can also solve the problem of blade wear causing the blade gaps to increase and the need for more blades.

[0056] Furthermore, the side limiting plate 04 is provided with a height adjustment edge 011 on its outer side. The height adjustment edge 011 is located below the limiting strip 07, and the top side of the height adjustment edge 011 is set to abut against the two ends of the first blade 05 and the second blade 06. The lifting stroke of the first blade 05 and the second blade 06 can be controlled by adjusting the height adjustment edge 011. It can be set according to the thickness of the board material, so as not to damage the PCB board when bending the board, and to ensure the production quality of the PCB board.

[0057] Furthermore: Two positioning posts 012 are fixedly installed on the outer side of the side limiting plate 04. Vertical threads 013 are formed on the positioning posts 012. A screw 014 is screwed into the vertical threads 013. The upper end of the screw 014 abuts against the height adjustment edge 011. The lower end of the screw 014 is formed with an internal hexagonal groove 015. The installation height of the height adjustment edge 011 can be controlled by twisting the screw 014, thereby controlling the lifting stroke of the first blade 05 and the second blade 06.

[0058] Furthermore, at least two vertical adjustment grooves 016 are formed on the height adjustment edge 011, and locking bolts 017 are installed in the vertical adjustment grooves 016 with clearance fit. The locking bolts 017 pass through the vertical adjustment grooves 016 and lock onto the side limiting plate 04. The locking bolts 017 can pass through the vertical adjustment grooves 016 to secure the height adjustment edge 011 to the side limiting plate 04, thereby ensuring the stable installation of the height adjustment edge 011.

[0059] Furthermore: a first side cover 025 is fixedly installed on the outer side of the height adjustment edge 011, and the first blade 05 and the second blade 06 are both installed between the first side covers 025 on the left and right sides with clearance fit.

[0060] Furthermore: the lead screw conveying mechanism 02 includes a drive motor 0201, a coupling 0202, a lead screw shaft 0203, and a lead screw drive block 0204. A motor base 023 is fixedly installed on the positioning base plate 01, and the drive motor 0201 is fixedly installed on the motor base 023. Lead screw support seats 024 are rotatably fitted at both ends of the lead screw shaft 0203, and the lead screw support seats 024 are fixedly installed on the positioning base plate 01. The drive motor 0201 drives the lead screw shaft 0203 to rotate through the coupling 0202. The lead screw drive block 0204 is screw-fitted onto the lead screw shaft 0203, and the roller assembly 03 is fixedly installed on the lead screw drive block 0204. The roller assembly 03 can be controlled to move back and forth by the drive of the lead screw motor, resulting in high stability.

[0061] Furthermore: The roller assembly 03 includes a sliding platform 0301 and two roller supports 0302. The sliding platform 0301 is fixedly mounted on the lead screw drive block 0204. The two roller supports 0302 are respectively fixedly mounted on the left and right ends of the upper side of the sliding platform 0301. The two roller supports 0302 are symmetrically arranged to each other. Several support rollers 0303 arranged in an equidistant array are rotatably installed inside the roller supports 0302. When the support rollers 0303 move, they press against the first blade 05 and the second blade 06 at the corresponding positions. When the roller assembly 03 slides once, the first blade 05 and the second blade 06 can be lifted by the several support rollers 0303 on both sides, thereby lifting the corresponding blades and simulating the action of folding plates. The arrangement of several support rollers 0303 can lift the first blade 05 and the second blade 06 multiple times, thereby realizing the action of rapid plate separation.

[0062] Furthermore: two guide rails 018 are fixedly installed on the positioning base plate 01, and two sliding blocks 019 are slidably installed on each guide rail 018. The sliding platform 0301 is fixedly installed above the four sliding blocks 019, making the forward and backward movement of the sliding platform 0301 more stable.

[0063] Furthermore: Two limiting top edges 020 are fixedly installed between the two side limiting plates 04. Multiple first blades 05 and multiple second blades 06 are fitted together between the two limiting top edges 020. Second side covers 021 are fixedly installed on both the front and rear sides of the two side limiting plates 04. The roller assembly 03 moves back and forth between the two second side covers 021. The setting of the limiting top edges 020 can ensure the stable installation of the first blades 05 and the second blades 06, allowing them to move up and down stably, while ensuring that there is no tilting during the up and down movement. The second side covers 021 can provide a covering and protection function to ensure the service life of the depaneling machine module.

[0064] This embodiment does not impose any limitation on the shape, material, structure, etc. of this utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model shall fall within the protection scope of this utility model.

Claims

1. A limiting structure for stacked movable blades, comprising a positioning frame and a plurality of blades; characterized in that: The positioning frame is fixedly installed on both the left and right sides with limit strips. Several protrusions are formed on the outer side of the limit strips. Several blades include several first blades and several second blades. The two ends of the bottom side of the first blade are respectively snapped onto the protrusions, and the two ends of the bottom side of the second blade are respectively snapped onto the limit strips.

2. The limiting structure for a stacked movable blade according to claim 1, characterized in that: The first blade and the second blade are both divided into arrays, and the array of first blades and array of second blades are arranged in an alternating and overlapping manner.

3. The limiting structure for a stacked movable blade according to claim 2, characterized in that: The number of the first blades in each group is equal to the number of the second blades in each group.

4. A limiting structure for a stacked movable blade according to any one of claims 1, 2, or 3, characterized in that: Both ends of the bottom side of the first blade are formed with first barbs, which are snapped onto the protrusion. Both ends of the bottom side of the second blade are formed with second barbs, which are snapped onto the limiting strip.

5. A limiting structure for a stacked movable blade according to any one of claims 1, 2, or 3, characterized in that: The protrusions are arranged in an array at equal intervals.

6. The limiting structure for a stacked movable blade according to claim 1, characterized in that: The positioning frame includes a positioning base plate and two side limiting plates. The two side limiting plates are fixedly installed on the left and right ends of the positioning base plate, respectively. The two side limiting plates are symmetrically arranged with each other, and the limiting strips are fixedly installed on the outer side of the side limiting plates one by one.

7. The limiting structure for a stacked movable blade according to claim 6, characterized in that: The side limiting plate is equipped with a height adjustment edge, and the two ends of the bottom sides of the first blade and the second blade respectively abut against the height adjustment edge.

8. The limiting structure for a stacked movable blade according to claim 7, characterized in that: A first side cover is fixedly installed on the outer side of the height adjustment edge, and the first blade and the second blade are both installed between the first side covers on the left and right sides with a clearance fit.

9. A limiting structure for a stacked movable blade according to any one of claims 6, 7, or 8, characterized in that: Two limiting top edges are fixedly installed between the two side limiting plates, and a number of first blades and a number of second blades are installed between the two limiting top edges with a gap fit.

10. The limiting structure for a stacked movable blade according to claim 9, characterized in that: A second side cover is fixedly installed on the outer side of the limiting top edge, and the positioning frame is located between the two second side covers.

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