Non-protrusion self-locking flat hinge capable of achieving seamless connection

Abstract

The invention discloses a seamlessly-connected bulge-free self-locking flat hinge, and relates to the technical field of hinge design. The hinge base is formed by integrating a main connecting rod and an L-shaped fixing plate, a protruding part is arranged on one side of the head end of the main connecting rod, the L-shaped fixing plate is arranged on the outer side of the protruding part, a first auxiliary shaft hole and two first main shaft holes are drilled in the main connecting rod, a locking block groove is machined in the tail end of the main connecting rod, two second main shaft holes are drilled in the auxiliary connecting rod, a connecting lug and a torsional spring groove are formed in the connecting end of the locking block, and a stepped groove is machined in the free end of the locking block. In the assembling process, the tail ends of the two hinge bases are attached to each other in a central symmetry mode, the four main shafts are inserted into the first main shaft holes, the two auxiliary shafts are inserted into the first auxiliary shaft holes, the two torsional springs are arranged on the inner sides of the auxiliary shafts in a sleeving mode, the two locking blocks are arranged on the outer sides of the auxiliary shafts in a sleeving mode, the two auxiliary connecting rods are inserted into the outer ends of the four main shafts, and the two L-shaped fixing plates fix the two connecting structures. Seamless connection of the connection structures at the two ends can be achieved in the folded and unfolded states, the surface does not protrude after unfolding, and the requirements of the panel antenna for the folding size and the unfolding flatness are met.

Description

Technical Field

[0001] The invention relates to the technical field of hinge design, in particular to a self-locking flat hinge with no protrusions and capable of seamless connection. Background Art

[0002] In order to meet the needs of communication and measurement, artificial satellites generally need to be equipped with antennas. Among them, foldable and unfoldable flat-panel antennas are currently the most widely used antenna structure.

[0003] Flat panel antennas, especially large-sized antennas, need to be seamlessly connected after unfolding, and have extremely high requirements for flatness. It is necessary to minimize the protrusion above the flat panel antenna surface. At the same time, since the satellite needs to be as small as possible during launch, the flat panel antenna also needs to be as seamlessly connected as possible when folded to reduce the space occupied. If ordinary hinges want to ensure seamless contact when folded, then after unfolding, due to structural reasons, at least half of the axis and part of the sleeve will protrude from the surface of the connection structure, thus affecting the flatness of the structure surface.

[0004] Therefore, it is necessary to design a self-locking flat hinge that can achieve seamless connection of the two end connection structures when folded, and automatically lock without protrusions after unfolding, for structures with high flatness requirements such as flat antennas of artificial satellites, so as to meet the requirements for occupied space when folded and flatness after unfolding. Summary of the invention

[0005] In order to address the shortcomings of the background technology, the present invention provides a self-locking flat hinge with seamless connection and no protrusions. Under the premise of ensuring the functions of unfolding and automatic locking, it can simultaneously achieve seamless connection of the connecting structures at both ends in the folded and unfolded states, and after unfolding, the hinge has no protrusions on the surface of the connecting structure, thereby meeting the strict requirements of the flat antenna for the folded volume and unfolded flatness.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a self-locking flat hinge without protrusions that can be seamlessly connected, comprising two hinge bases, two secondary connecting rods, two locking blocks, two secondary shafts, two torsion springs and four main shafts, wherein: each of the hinge bases is made of a main connecting rod and an L-shaped fixing plate as a whole, the main connecting rod body is a rectangular cross-section rod and one side of its head end is transversely thickened and provided with a protrusion, the thickness of the protrusion is consistent with the thickness of the rectangular cross-section rod, the L-shaped fixing plate is horizontally arranged at the outer edge of the protrusion, a secondary shaft hole and two main shaft holes are transversely drilled on the main connecting rod, and the The two main shaft holes are respectively located at the center of the raised part and the position near the end of the rectangular cross-section rod. The secondary shaft hole is located above the main shaft hole adjacent to the raised part on the rectangular cross-section rod. A locking block groove is processed at the end of the rectangular cross-section rod of the main connecting rod. The locking block groove is composed of an arc-shaped notch and a convex strip arranged horizontally on its top. Each of the secondary connecting rod bodies is a rectangular cross-section rod with rounded corners at both ends. Two main shaft holes are drilled horizontally on the secondary connecting rod. The two main shaft holes are respectively located near the two ends of the secondary connecting rod. Each of the locking block bodies is a rectangular block and its width is consistent with the thickness of the raised part of the hinge base. A connecting ear is integrally arranged on the outer side of the connecting end, and two secondary shaft holes are drilled transversely. Space is reserved on the inner side of the connecting end of the locking block and a torsion spring groove is machined. A stepped groove is transversely machined on the top of the free end of the locking block. During assembly, the two hinge bases are placed together so that the side with the raised portion at the end of the rectangular cross-section rod is close to each other. The four main shafts are grouped in twos, and the two main shafts in each group are respectively inserted into the main shaft hole one of the hinge base located at the raised portion and the main shaft hole one of the other hinge base near the end. The two secondary shafts are respectively inserted into the secondary shaft holes one of the two hinge bases. The two torsion springs are respectively mounted on the inner sides of the two secondary shafts. The two locking blocks are respectively The secondary shaft holes are mounted on the outside of the two secondary shafts through the secondary shaft holes and the corresponding torsion springs are ensured to be inserted into the torsion spring grooves. The two secondary connecting rods are inserted into the outer ends of the four main shafts through the four main shaft holes. The L-shaped fixing plates of the two hinge bases are respectively fixed to the two connecting structures by bolts. The two connecting structures are respectively machined with hinge grooves for accommodating the hinge bases at the connecting ends of the folding side surfaces. The two connecting structures are respectively machined with bolt grooves at corresponding positions on the back side of the folding side to hide the bolts under the back side of the folding side. An arc-shaped avoidance groove is laterally machined at the corresponding position on the opening and closing side of one of the connecting structures to make room for the corners of the other connecting structure.

[0007] Furthermore, the two hinge bases are respectively processed with sliding surface one at the bottom of one side of the convex strip of the locking block groove, and the sliding surface one is an arc-shaped concave structure. The two locking blocks are respectively processed with sliding surface two on one side of the step groove, and the sliding surface two is an arc-shaped convex structure. When the hinge is fully expanded to the horizontal, the sliding surface one is locked and matched with the corresponding sliding surface two.

[0008] Furthermore, the two secondary shafts and the four main shafts are assembled with the two hinge bases using interference fit, the two locking blocks are assembled with the two secondary shafts, and the two secondary connecting rods are assembled with the four main shafts using clearance fit.

[0009] Furthermore, a weight-reducing hollow portion is drilled transversely on the main connecting rods of the two hinge bases, and the weight-reducing hollow portion is located in the middle of the two main shaft holes.

[0010] Furthermore, the two secondary connecting rods are respectively transversely drilled with a second weight-reducing hollow portion, and the second weight-reducing hollow portion is located in the middle position of the secondary connecting rod.

[0011] Furthermore, the machining width of the hinge grooves of the two connecting structures is the same as the maximum transverse width of the hinge, thereby restricting the two secondary connecting rods to prevent the hinge from disintegrating.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention is mainly used for structures with high requirements on flatness, such as flat-panel antennas of artificial satellites. It is designed based on a cross four-bar structure and is a centrally symmetrical structure, which is conducive to processing and production, and can achieve seamless connection of the connecting structures at both ends in the folded and unfolded state, can be normally unfolded and automatically locked, and can still ensure seamless connection of the connecting structures at both ends after unfolding and locking, and there is no part of the hinge protruding from the surface of the connecting structure, which meets the application requirements of structures such as flat-panel antennas carried in artificial satellites for folding volume and unfolding flatness. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is an exploded schematic diagram of the hinge of the present invention;

[0014] Figure 2 is a schematic diagram of the hinge of the present invention in a fully folded state;

[0015] Figure 3 It is a schematic diagram of a partially unfolded state of the hinge of the present invention;

[0016] Figure 4 is a schematic diagram of the locked state of the hinge of the present invention in a fully extended state;

[0017] Figure 5 It is a schematic diagram of the principle of the folding and unfolding process of the hinge of the present invention.

[0018] In the figure: 110 and 120 are hinge bases; 101 is the main connecting rod; 102 is an L-shaped fixing plate; 103 and 104 are main shaft hole one; 105 is secondary shaft hole one; 106 is weight reduction hollow one; 107 is a locking block groove; 108 is sliding surface one; 210 and 220 are secondary connecting rods; 201 and 202 are main shaft hole two; 203 is weight reduction hollow two; 310 and 320 are locking blocks; 301 is secondary shaft hole two; 302 is a torsion spring groove; 303 is sliding surface two; 410, 420, 430 and 440 are main shafts; 450 and 460 are secondary shafts; 510 and 520 are torsion springs; 600 and 700 are connecting structures; 601 and 701 are hinge grooves; 602 and 702 are bolt grooves; 603 is an arc-shaped avoidance groove. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] like Figure 1 to Figure 5 As shown, a self-locking flat hinge with no protrusions and seamless connection includes two hinge bases 110 and 120, two secondary connecting rods 210 and 220, two locking blocks 310 and 320, two secondary shafts 450 and 460, two torsion springs 510 and 520, and four main shafts 410, 420, 430 and 440.

[0021] The self-locking flat hinge is a centrally symmetrical structure. Figure 1As shown, the disassembled structure of each component is shown. Among them, since the structures of the two hinge bases 110 and 120 are completely the same, the hinge base 110 is taken as an example to describe its specific structure. It is made of a main connecting rod 101 and an L-shaped fixing plate 102 as a whole. The main connecting rod 101 is a rectangular cross-section rod and one side of its head end is transversely thickened and provided with a raised portion. The thickness of the raised portion is consistent with the thickness of the rectangular cross-section rod. The L-shaped fixing plate 102 is horizontally arranged at the outer edge of the raised portion. The L-shaped fixing plate 102 is processed with multiple bolt holes for bolt fixing of the structure to be connected. A secondary shaft hole 105, a weight-reducing hollow 106, and two main shaft holes 103 and 104 are drilled transversely on the main connecting rod 101. The two main shaft holes 103 and 104 are respectively drilled at the center position of the raised portion of the main connecting rod 101 and near the end position of the rectangular cross-section rod. The weight-reducing hollow 106 is drilled on the rectangular cross-section rod of the main connecting rod 101 and is located in the middle position of the two main shaft holes 103 and 104. The secondary shaft hole 105 is drilled on the rectangular cross-section rod of the main connecting rod 101 and is located above between the main shaft hole 103 of the raised portion and the weight-reducing hollow 106. A locking block groove 107 is machined at the end of the rectangular cross-section rod of the main connecting rod 101. The locking block groove 107 is composed of an arc-shaped notch and a convex strip arranged horizontally on the top thereof. A sliding surface 108 is machined at the bottom of one side of the convex strip of the locking block groove 107. The sliding surface 108 is an arc-shaped concave structure. The locking block grooves 107 of the two hinge bases 110 and 120 are respectively used for locking with the two locking blocks 310 and 320 in the locking stage. Since the two secondary connecting rods 210 and 220 have completely the same structure, the secondary connecting rod 210 is taken as an example to describe its specific structure. Its main body is a rectangular cross-section rod with rounded corners at both ends. A weight-reducing hollow 203 and two main shaft holes 201 and 202 are drilled horizontally on the secondary connecting rod 210. The two main shaft holes 201 and 202 are respectively drilled near the two ends of the secondary connecting rod 210, and the weight-reducing hollow 203 is drilled in the middle of the secondary connecting rod 210.Since the structures of the two locking blocks 310 and 320 are completely consistent, the specific structure is described by taking the locking block 310 as an example. The main body is a rectangular block and the width is consistent with the thickness of the raised part of the hinge base 110 / 120. A connecting ear is integrally arranged on the outer side of the connecting end of the locking block 310 and a secondary shaft hole 301 is drilled transversely. Space is reserved on the inner side of the connecting end of the locking block 310 and a torsion spring groove 302 is processed. A step groove is transversely processed on the top of the free end of the locking block 310, and a sliding surface 303 is processed on one side of the step groove. The sliding surface 303 is an arc-shaped convex structure. When the hinge is completely When unfolded to horizontal, the stepped grooves at the top of the free ends of the two locking blocks 310 and 320 respectively engage with the convex strips at the top of the locking block grooves 107 at the ends of the two hinge bases 110 and 120 to achieve locking. The arc-shaped outward-convex sliding surface 2 303 on one side of the stepped groove ensures that the free ends of the two locking blocks 310 and 320 will not be stuck during the hinge unfolding process. The arc-shaped inward-convex sliding surface 108 on one side of the locking block groove 107 is adapted to the sliding surface 2 303 to ensure seamless contact between the free ends of the two locking blocks 310 and 320 and the ends of the two hinge bases 110 and 120 after the hinge is fully unfolded.

[0022] When assembling the hinge, place the two hinge bases 110 and 120 in a centrally symmetrical manner so that the side with the raised portion at the end of the rectangular cross-section rod is pressed together, and assemble one side. First, insert one end of the two main shafts 410 and 420 into the main shaft hole 103 located at the raised portion of the hinge base 110 and the main shaft hole 104 near the end of the hinge base 120, respectively, and then insert one of the secondary shafts 450 into the secondary shaft hole 105 of the hinge base 110, then put one of the torsion springs 510 on the secondary shaft 450, and then put one of the locking blocks 310 on the secondary shaft 450 through its secondary shaft hole 2 301, and ensure that the torsion spring 510 is stuck in the corresponding torsion spring groove 302, and finally, insert one of the secondary connecting rods 210 through the two main shaft holes The second two 201 and 202 are inserted into the outer ends of the two main shafts 410 and 420; the assembly on the other side is similar. First, one end of the remaining two main shafts 430 and 440 is respectively inserted into the main shaft hole 103 located at the raised part of the hinge base 120 and the main shaft hole 104 near the end position of the hinge base 110, and then another secondary shaft 460 is inserted into the secondary shaft hole 105 of the hinge base 120, and then another torsion spring 520 is mounted on the secondary shaft 460, and then another locking block 320 is mounted on the secondary shaft 460 through its secondary shaft hole 201, and it is ensured that the torsion spring 520 is stuck in the corresponding torsion spring groove 302, and finally another secondary connecting rod 220 is inserted into the outer ends of the two main shafts 430 and 440 through the two main shaft holes 201 and 202. It is worth noting that the two secondary shafts 450 and 460 and the four main shafts 410, 420, 430 and 440 adopt interference fit when assembled with the two hinge bases 110 and 120, and can be inserted and fixed without other parts; and the two locking blocks 310 and 320 adopt clearance fit when assembled with the two secondary shafts 450 and 460, and the two secondary connecting rods 210 and 220 adopt clearance fit when assembled with the four main shafts 410, 420, 430 and 440, and can rotate freely.

[0023] Combination Figure 2 and Figure 5 As shown, the fully folded state of the hinge and the corresponding structural morphology of the hinge at this stage (see Figure 5In actual application, the two connecting structures 600 and 700 to be connected are assembled through self-locking flat hinges, and a hinge groove 601 for accommodating one of the hinge bases 110 is processed at the connecting end of the folded side surface of one of the connecting structures 600, and a hinge groove 701 for accommodating another hinge base 120 is processed at the connecting end of the folded side surface of the other connecting structure 700. The two hinge bases 110 and 120 are respectively connected and fixed to the L-shaped fixing plate 102 and the two connecting structures 600 and 700 by bolts. Since the hinges are in a loose state after assembly and are easy to disintegrate, they can be controlled during processing. The width of the hinge grooves 601 and 701 is the same as the maximum width of the hinge in the transverse direction, so that the two secondary connecting rods 210 and 220 in the hinge are restricted by the side walls of the hinge grooves 601 and 701 to prevent the hinge from disintegrating. In addition, a bolt groove 602 is processed in cooperation with the bolt installation position corresponding to the bolt installation position of the hinge base 110 on the back of the folding side of one of the connection structures 600, and a bolt groove 702 is processed in cooperation with the bolt installation position corresponding to the bolt installation position of the hinge base 120 on the back of the folding side of the other connection structure 700, so that the bolt is hidden under the back of the folding side of the two connection structures 600 and 700, reducing the protruding part. In this state, the folding side surfaces of the two connection structures 600 and 700 are in seamless contact, the main connecting rod 101 of the two hinge bases 110 and 120 and the two secondary connecting rods 210 and 220 form a cross four-link structure shaped like an hourglass, and the two locking blocks 310 and 320 are blocked by the corresponding hinge bases 120 and 110 and cannot rotate, and are not in a locked position.

[0024] Combination Figure 3 and Figure 5 As shown, the partially unfolded state of the hinge and the corresponding structural morphology of the hinge at this stage (see Figure 5 The hinge begins to unfold under the action of external force. Assuming that one of the connection structures 600 is fixed, the other connection structure 700 moves along with the main connecting rod 101 of the corresponding hinge base 120, and the trajectory of a certain point is not circular. At this time, the two locking blocks 310 and 320 start to deflect under the action of the two torsion springs 510 and 520 while following the movement, and the free ends of the two locking blocks 310 and 320 are always tightly attached to the main connecting rod 101 of the corresponding two hinge bases 120 and 110. During this period, the sliding surface 2 303 set at the free ends of the two locking blocks 310 and 320 can effectively prevent them from getting stuck somewhere during the movement. After the two connecting structures 600 and 700 are unfolded to a certain angle, there is a position on the opening and closing side of one of the connecting structures 600 that may hinder the other connecting structure 700. Therefore, an arc-shaped avoidance groove 603 can be laterally polished at the corresponding position of the opening and closing side of one of the connecting structures 600 to make room for the corners of the other connecting structure 700 that is turned here, so that it can continue to be fully unfolded.

[0025] Combination Figure 4 and Figure 5 As shown, the fully extended state of the hinge and the corresponding structural morphology of the hinge at this stage are shown (see Figure 5 When the opening and closing sides of the two connection structures 600 and 700 come into contact, the corners of the movable connection structure 700 just turn out from the arc-shaped avoidance groove 603 of the fixed connection structure 600 to avoid interference between the two connection structures 600 and 700. Finally, the main connecting rod 101 of the two hinge bases 110 and 120 and the two secondary connecting rods 210 and 220 form a straight line. At this time, the free ends of the two locking blocks 310 and 320 are respectively locked with the locking block grooves 107 processed at the ends of the corresponding two hinge bases 120 and 110, completing the locking state of the hinge.

[0026] When fully extended, the hinge has two possible motions:

[0027] The first is that the angle between the folding side surfaces of the two connecting structures 600 and 700 changes, and the structure moves in a rotational and translational manner. When the angle tends to increase, that is, the hinge is over-expanded, the bottoms of the opening and closing sides of the two connecting structures 600 and 700 will prevent further rotational translation due to their mutual contact; when the angle tends to decrease, that is, the hinge is folded back, the upper side of the step grooves at the free ends of the two locking blocks 310 and 320 is squeezed by the top convex strips of the locking block grooves 107 at the ends of the two hinge bases 120 and 110. Since the force point is higher than the axis of the secondary shaft hole 2 301 of the two locking blocks 310 and 320, the free ends of the two locking blocks 310 and 320 tend to rotate upward, but the convex strips at the top of the corresponding locking block grooves 107 block the movement trend, making the free ends of the two locking blocks 310 and 320 unable to rotate, and the locking cannot be automatically released, preventing the hinge from further rotating and translating.

[0028] The second type is that the folded side surfaces of the two connecting structures 600 and 700 remain parallel, the two secondary connecting rods 210 and 220 also remain parallel, and the structure moves in a parallelogram-shaped translational manner. When the movable connecting structure 700 tends to move downward, the opening and closing side surfaces of the two connecting structures 600 and 700 contact each other, preventing the structure from moving further; when the movable connecting structure 700 tends to move upward, the upper edges of the opening and closing side surfaces of the two connecting structures 600 and 700, as well as the adjacent surfaces of the two locking blocks 310 and 320 and the corresponding two hinge bases 120 and 110 will all contact, preventing the structure from moving further.

[0029] In summary, the hinge structure combined with the two locking blocks 310 and 320 and the two connecting structures 600 and 700 can achieve locking in a fully unfolded state.

[0030] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms of assembly without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0031] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A self-locking flat hinge with no protrusions and seamless connection, characterized in that: The self-locking flat hinge is a centrally symmetrical structure, including two hinge bases, two secondary connecting rods, two locking blocks, two secondary shafts, two torsion springs and four main shafts, wherein: each of the hinge bases is made of a main connecting rod and an L-shaped fixing plate as a whole, the main connecting rod body is a rectangular cross-section rod and one side of its head end is transversely thickened and provided with a raised portion, the thickness of the raised portion is consistent with the thickness of the rectangular cross-section rod, the L-shaped fixing plate is horizontally arranged at the outer edge of the raised portion, and a secondary shaft hole 1 and two main shaft holes 1 are transversely drilled on the main connecting rod, and the two main shaft holes 1 are respectively located at the center position of the raised portion and the adjacent end position of the rectangular cross-section rod, the secondary shaft hole 1 is located above the main shaft hole 1 adjacent to the raised portion on the rectangular cross-section rod, and a locking block groove is processed at the end of the rectangular cross-section rod of the main connecting rod, and the locking block groove is composed of an arc-shaped notch and a convex strip arranged transversely on its top; each of the secondary connecting rod bodies is a rectangular cross-section rod with rounded corners at both ends, and two main shaft holes 2 are drilled transversely on the secondary connecting rod, and the two main shaft holes 2 are respectively located on the secondary connecting rod adjacent to the two ends; each of the locking block bodies is a rectangular block and its width is consistent with the thickness of the raised portion of the hinge base, and a connecting block is integrally arranged on the outer side of the locking block connection end The ear is drilled with two secondary shaft holes horizontally, space is reserved on the inner side of the locking block connection end and a torsion spring groove is machined, and a stepped groove is machined horizontally on the top of the free end of the locking block; when assembling, the two hinge bases are placed together so that the side with the raised portion at the end of the rectangular cross-section rod is close to each other, the four main shafts are grouped in twos, and the two main shafts in each group are respectively inserted into the main shaft hole one of the hinge base located at the raised portion and the main shaft hole one of the other hinge base near the end position, the two secondary shafts are respectively inserted into the secondary shaft holes one of the two hinge bases, the two torsion springs are respectively mounted on the inner sides of the two secondary shafts, and the two locking blocks are respectively inserted through the secondary The two shaft holes are mounted on the outside of the two secondary shafts and ensure that the corresponding torsion springs are inserted into the torsion spring grooves. The two secondary connecting rods are inserted into the outer ends of the four main shafts through the four main shaft holes. The L-shaped fixing plates of the two hinge bases are respectively fixed to the two connecting structures by bolts. The two connecting structures are respectively processed with hinge grooves for accommodating the hinge bases at the connecting ends of the folding side surfaces. The two connecting structures are respectively processed with bolt grooves at the corresponding positions of the back sides of the folding sides to hide the bolts under the back sides of the folding sides. An arc-shaped avoidance groove is transversely processed at the corresponding position of the opening and closing side of one of the connecting structures to make room for the corners of the other connecting structure.

2. A self-locking flat hinge with no protrusions and seamless connection according to claim 1, characterized in that: The two hinge bases are respectively processed with sliding surface one at the bottom of one side of the convex strip of the locking block groove, and the sliding surface one is an arc-shaped concave structure. The two locking blocks are respectively processed with sliding surface two on one side of the step groove, and the sliding surface two is an arc-shaped convex structure. When the hinge is fully unfolded to the horizontal, the sliding surface one is locked and matched with the corresponding sliding surface two.

3. A seamlessly connected, protrusion-free, self-locking flat hinge according to claim 1 or 2, characterized in that: The two secondary shafts and the four main shafts are assembled with the two hinge bases by interference fit, and the two locking blocks are assembled with the two secondary shafts, and the two secondary connecting rods are assembled with the four main shafts by clearance fit.

4. A self-locking flat hinge with no protrusions and capable of seamless connection according to claim 1, characterized in that: A weight-reducing hollow portion 1 is drilled transversely on the main connecting rods of the two hinge bases, and the weight-reducing hollow portion 1 is located in the middle of the two main shaft holes 1.

5. The self-locking flat hinge with no protrusion and seamless connection according to claim 1, characterized in that: The two secondary connecting rods are also respectively provided with a second weight-reducing hollow through hole drilled transversely, and the second weight-reducing hollow through hole is located in the middle position of the secondary connecting rod.

6. A seamlessly connected, protrusion-free, self-locking flat hinge according to claim 1, characterized in that: The machining width of the hinge grooves of the two connecting structures is the same as the maximum transverse width of the hinge, so as to restrict the two secondary connecting rods to prevent the hinge from disintegrating.

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