A drop test device for introducing a cable preform end assembly

Abstract

The application discloses a kind of introduction cable preform end assembly drop test device, including base;The bottom end of the both sides of the base is hinged with load-bearing plate by hinge;By operator sliding clamping plate A and horizontal crossbar backwards, it is fixed on the object plate, while the metal impact plate in the base is removed, and is clamped in the base;Subsequently, artificially take out the introduction cable preform, and lead out a section through between clamping plate A and clamping plate B, and make the section that it leads out adhere to the bottom of horizontal crossbar, then release hand, the end of introduction cable preform leads out will swing around the part that it is fixed in clamping plate A and clamping plate B under the action of gravity, and impact on metal impact plate under the action of inertial force;Relative to prior art, steel ruler is arranged in the device on the both sides of support frame, can ensure that the introduction cable drop height is consistent and adjustable, the result error of repeated test is relatively small, and the accuracy is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drop test device, and particularly relates to a drop test device for a pre-assembled end assembly of an optical cable. BACKGROUND

[0002] The pre-assembled end assembly of an optical cable refers to an optical fiber active connector plug assembled on an optical cable. According to different structures of the optical cable, the pre-assembled end assembly is divided into a butterfly-shaped optical cable assembly and a circular optical cable assembly. According to the structure of the assembly, the pre-assembled end assembly is divided into a double-end pre-assembled end assembly and a single-end pre-assembled end assembly. The pre-assembled end assembly is mainly applied to the end of an access network optical network or other occasions of transmitting optical signals, and is mainly laid in indoor pipe holes or outdoor overheads.

[0003] During transportation and installation of the pre-assembled end assembly of the optical cable, the pre-assembled end assembly is affected by various adverse natural environmental conditions or human factors. The drop test is mainly used to simulate the free drop of the assembly during transportation and installation, and to investigate the anti-accident impact resistance of the assembly. In the prior art, the drop test for the pre-assembled end assembly of the optical cable mainly relies on a metal impact plate and a support frame. The metal impact plate is arranged on one side of the bottom of the support frame. One end of the pre-assembled end assembly of the optical cable is stretched to be 90 degrees with the support frame. Then, the hand is released, and the gravity drives the one end of the pre-assembled end assembly of the optical cable to slide down, and finally impacts on the metal impact plate, so as to complete the drop test and obtain test data.

[0004] Other mechanical property tests of the pre-assembled end assembly of the optical cable have force value requirements, and a stretching machine or the like must be used, and the operation is relatively standardized. The drop test is relatively simple. The current test device does not have a scale, and when the drop test is performed, a single variable cannot be controlled, thereby causing large test error and low result accuracy. Meanwhile, a clamp for fixing the optical cable has large abrasion to the sheath of the optical cable. SUMMARY

[0005] In order to make up for the deficiencies of the prior art and solve at least one of the above problems, the present application provides a drop test device for a pre-assembled end assembly of an optical cable.

[0006] The utility model provides an introduction cable preform end assembly drop test device, including the base, both sides bottom end of base is hinged with the bearing plate through the hinge, one end top of base is firmly connected with the support frame, and the top of support frame is firmly connected with the object bearing plate, and the side of support frame is embedded with the connection steel plate ruler, one end of object bearing plate is firmly connected with the clamping plate A, and one side of clamping plate A is movably connected with the clamping plate B, one end of clamping plate A away from object bearing plate is firmly connected with horizontal cross bar, and clamping plate B is movably connected on horizontal cross bar, the middle part of base is connected with the metal impact plate, and metal impact plate is parallel with support frame, the top surface of object bearing plate is used for carrying the introduction cable preform, and one end of introduction cable preform penetrates clamping plate A, clamping plate B.

[0007] Preferably, the base is provided with a P-shaped structure, and a receiving groove is formed in the base; a clamping block A is arranged on the base corresponding to the metal impact plate, and the metal impact plate is clamped in the inner side of the clamping block A.

[0008] Preferably, a clamping groove is formed on one end of the base away from the metal impact plate, and a clamping block B corresponding to the clamping groove is firmly connected on the bearing plate; the bearing plate is clamped in the clamping groove through the clamping block B.

[0009] Preferably, a movable groove is formed on one end of the base corresponding to the clamping groove, and a pressing plate is movably connected in the movable groove; a pressing block is firmly connected on the inner side of the pressing plate, and the pressing block is movably connected in the clamping groove.

[0010] Preferably, a connecting shaft is firmly connected on one end of the clamping plate A, and the connecting shaft is respectively located at both ends of the clamping plate A with the horizontal cross bar; a roller is rotatably connected on the top of one end of the clamping plate A close to the object bearing plate, and the roller is used for guiding the introduction cable preform.

[0011] Preferably, a sliding groove is formed on one end of the object bearing plate close to the clamping plate A, and the connecting shaft is slidably connected in the sliding groove; the sliding groove penetrates the object bearing plate on both sides and the bottom side.

[0012] Preferably, a pin shaft A and a clamping plate are firmly connected on both sides of the connecting shaft; the pin shaft A and the clamping plate are slidably connected in the sliding groove; the clamping plate is provided with an L-shaped structure.

[0013] Preferably, a notch is formed in the horizontal cross bar corresponding to the clamping plate B, and a horizontally arranged spring rod is firmly connected in the notch; a connecting part is firmly connected on the top of one end of the clamping plate B, and the connecting part penetrates in the notch; the spring rod penetrates in the connecting part.

[0014] Preferably, an extension rod is sleeved on one end of the horizontal cross bar away from the object bearing plate, and a pin shaft B is firmly connected on the top surface of the extension rod; the extension rod is slidably connected on the horizontal cross bar through the pin shaft B.

[0015] Preferably, the clamping plate A and the clamping plate B are spliced together upside down, and the clamping plate A and the clamping plate B are provided with abutting blocks inside; the abutting blocks inside the clamping plate A and the abutting blocks inside the clamping plate B are alternately arranged upside down, and the abutting blocks inside the clamping plate A are lower than the abutting blocks inside the clamping plate B.

[0016] The present application has the advantages of:

[0017] The present application has the advantages of: BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0019] Figure 1 It is a first perspective view of one embodiment of the present application;

[0020] Figure 2 It is a second perspective view of one embodiment of the present application;

[0021] Figure 3 It is a sectional perspective view of one embodiment of the present application;

[0022] Figure 4 It is an enlarged schematic view of the A part structure in one embodiment of the present application;

[0023] Figure 5 It is a perspective view of the connecting shaft, the clamping plate A and the horizontal crossbar in one embodiment of the present application;

[0024] Figure 6 It is a side view of one embodiment of the present application.

[0025] In the figure: 1. Base; 11. Load-bearing plate; 12. Block A; 13. Hinge; 14. Storage slot; 15. Slot; 16. Extrusion plate; 17. Block B; 18. Movable slot; 2. Support frame; 21. Steel ruler; 3. Support plate; 31. Slide; 4. Clamp A; 41. Roller; 42. Connecting shaft; 43. Clamp; 44. Pin A; 51. Horizontal crossbar; 52. Extension rod; 53. Pin B; 54. Clamp B; 55. Spring rod; 6. Metal impact plate; 7. Introduction of optical cable preform. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] See also Figures 1-6 As shown, a drop test device for introducing optical cable prefabricated terminal components includes a base 1, a support frame 2, a support plate 3, a steel ruler 21, a horizontal cross bar 51 and a splint unit; the bottom ends of both sides of the base 1 are hinged with load-bearing plates 11 through hinges 13; wherein the load-bearing plates 11 are used to support the base 1 and maintain the stability of the base 1; the top of one end of the base 1 is fixedly connected to a support frame 2, and the top of the support frame 2 is fixedly connected to a support plate 3; the support frame 2 is used to carry the support plate 3, and the support plate 3 is used to support the splint unit and the introduction optical cable prefabricated component 7; the side of the support frame 2 is embedded with a connecting steel ruler 21; the splint unit The element includes a plywood A4 and a plywood B54; one end of the support plate 3 is fixedly connected to the plywood A4, and one side of the plywood A4 is movably connected to the plywood B54; the end of the plywood A4 away from the support plate 3 is fixedly connected to the horizontal crossbar 51, and the plywood B54 is movably connected to the horizontal crossbar 51; wherein the horizontal crossbar 51 is used to limit the pulling position of the introduced optical cable preform 7; the middle part of the base 1 is clamped with a metal impact plate 6, and the metal impact plate 6 is parallel to the support frame 2; the top surface of the support plate 3 is used to carry the introduced optical cable preform 7, and one end of the introduced optical cable preform 7 passes through the plywood A4 and the plywood B54;

[0028] Specifically, in the prior art, other mechanical performance tests of the optical cable lead-in prefabricated end assembly require the use of a tension machine and the like, and the operation is relatively standardized. The drop test is relatively simple, and the current test device does not have a scale. When the drop test is performed, a single variable cannot be controlled, thereby causing a large test error and low result accuracy. Meanwhile, the clamp for fixing the optical cable lead-in has a large abrasion on the sheath of the optical cable lead-in. When the device is used, first, the load-bearing plates 11 on both sides of the base 1 are separated from the base 1, and the load-bearing plates 11 are expanded to both sides by means of the hinges 13 and are laid flat on the ground, thereby playing a supporting effect. Then, the operator rotates the clamping plate A4 and makes the clamping plate A4 and the horizontal crossbar 51 change from parallel to the support frame 2 to 90° with the support frame 2. When the clamping plate A4, the horizontal crossbar 51, and the support frame 2 are at 90°, the operator slides the clamping plate A4 and the horizontal crossbar 51 backward to make them fixed on the object-receiving plate 3. Meanwhile, the metal impact plate 6 in the base 1 is taken out and is clamped on the base 1. Then, the optical cable lead-in prefabricated part 7 is manually taken out, and a section of the optical cable lead-in prefabricated part 7 is led through the clamping plate A4 and the clamping plate B54 and is attached to the bottom of the horizontal crossbar 51. Then, the operator releases the optical cable lead-in prefabricated part 7. The end of the optical cable lead-in prefabricated part 7 will swing around the part of the optical cable lead-in prefabricated part 7 fixed on the clamping plate A4 and the clamping plate B54 under the action of gravity and will impact on the metal impact plate 6 under the action of inertial force. Specifically, the section of the optical cable lead-in prefabricated part 7 is set to 2 meters, and the end of the optical cable lead-in prefabricated part 7 is lifted to the bottom of the horizontal crossbar 51. Then, the end of the optical cable lead-in prefabricated part 7 is freely dropped. The drop test is completed after the end of the optical cable lead-in prefabricated part 7 is repeatedly dropped for 8 times. In the device, the steel plate ruler 21 is arranged on both sides of the support frame 2, which can ensure that the falling height of the optical cable lead-in is consistent and adjustable, the error of the results of repeated tests is relatively small, and the accuracy is ensured.

[0029] As an embodiment of the present application, the base 1 is arranged in a P-shaped structure, and the receiving groove 14 is arranged in the base 1. The base 1 arranged in a P-shaped structure and the receiving groove 14 arranged in the base 1 can be used to limit the horizontal crossbar 51 and the metal impact plate 6 after folding and storage. The clamping block A12 is arranged on the base 1 corresponding to the metal impact plate 6, and the metal impact plate 6 is clamped on the inner side of the clamping block A12.

[0030] Specifically, the clamping block A12 arranged on the base 1 can clamp the metal impact plate 6 taken out between the clamping block A12 and the base 1, thereby facilitating the fixation of the metal impact plate 6. After the optical cable lead-in prefabricated part 7 is freely dropped, the metal impact plate 6 can be accurately hit, thereby simulating the drop.

[0031] As an embodiment of the present invention, a slot 15 is provided on the base 1 at one end away from the metal impact plate 6, and a block B17 corresponding to the slot 15 is fixedly connected to the load-bearing plate 11; wherein the slot 15 provided on the base 1 can be used to fix the block B17 on the load-bearing plate 11, and when the block B17 on the load-bearing plate 11 is engaged in the slot 15, the load-bearing plate 11 can be fixed on the base 1, which is convenient for movement and carrying, and when it is hinged and laid flat on the ground through the hinge 13, it can provide a load-bearing effect; the load-bearing plate 11 is engaged in the slot 15 through the block B17.

[0032] As an embodiment of the present invention, a movable groove 18 is provided on one end of the base 1 corresponding to the card slot 15, and an extrusion plate 16 is movably connected in the movable groove 18; the extrusion plate 16 arranged on one side of the base 1 can be pressed inward under human power, and the pressure block on the inside of the extrusion plate 16 is passed through the card slot 15, so that the card block B17 in the card slot 15 can be squeezed out, thereby separating the load-bearing plate 11 from the base 1; a pressure block is fixed to the inside of the extrusion plate 16, and the pressure block is movably connected in the card slot 15.

[0033] As an embodiment of the present invention, one end of the plywood A4 is fixedly connected to a connecting shaft 42, and the connecting shaft 42 and the horizontal cross bar 51 are respectively located at both ends of the plywood A4; wherein the connecting shaft 42 on one side of the plywood A4 can fix the plywood A4 and the horizontal cross bar 51 together on the support plate 3, that is, the connecting shaft 42 can pass through the support plate 3; the plywood A4 is rotatably connected to the top of one end of the support plate 3 with a roller 41, and the roller 41 is used to guide the introduction of the optical cable preform 7;

[0034] Specifically, the roller 41 arranged on the side of the splint A4 close to the supporting plate 3 can guide the end of the introduced optical cable preform 7 when the end of the introduced optical cable preform 7 is led out and passes through between the splint A4 and the splint B54. The roller 41 is made of rubber material, which can prevent the end of the introduced optical cable preform 7 from being damaged.

[0035] As an embodiment of the present invention, a sliding groove 31 is formed at one end of the support plate 3 close to the clamping plate A4, and the connecting shaft 42 is slidably connected in the sliding groove 31; the two sides and the bottom of the sliding groove 31 pass through the support plate 3;

[0036] Specifically, the slide groove 31 arranged in the supporting plate 3 passes through the supporting plate 3 on both sides and the bottom side. The connecting shaft 42 can slide in the slide groove 31. The slide groove 31 is used to meet the horizontal sliding and rotational retraction actions of the connecting shaft 42 and the splint A4.

[0037] As an embodiment of the present application, the connecting shaft 42 is fixed with a pin shaft A44 and a clamping plate 43 on both sides; the pin shaft A44 and the clamping plate 43 are slidingly connected in the sliding groove 31; the clamping plate 43 is provided in an L-shaped structure.

[0038] Specifically, the pin shaft A44 and the clamping plate 43 are fixed on both sides of the connecting shaft 42, wherein the pin shaft A44 can slide on both sides of the sliding groove 31, and the clamping plate 43 can also slide on both sides of the sliding groove 31; the pin shaft A44 is fixed by a nut, thereby indirectly fixing the connecting shaft 42 and the clamping plate A4, and the clamping plate 43 is used to support the connecting shaft 42 and the clamping plate A4; when the connecting shaft 42, the clamping plate A4 and the horizontal cross bar 51 need to be retracted, the connecting shaft 42, the clamping plate A4 and the horizontal cross bar 51 are slid outwardly, the clamping plate 43 is separated from the sliding groove 31, then the connecting shaft 42 is rotated, so that the clamping plate A4, the connecting shaft 42 and the horizontal cross bar 51 are all rotated, and the horizontal cross bar 51 is retracted in the receiving groove 14 away from one end of the support plate 3; the top of the sliding groove 31 also penetrates the support plate 3, and the connecting shaft 42 can slide on the top of the sliding groove 31 and penetrate the top of the support plate 3 when the connecting shaft 42 is rotated.

[0039] As an embodiment of the present application, a notch is formed in the horizontal cross bar 51 corresponding to the clamping plate B54, and a horizontally arranged spring rod 55 is fixed in the notch; one end of the clamping plate B54 is fixed with a connecting portion, and the connecting portion penetrates in the notch; the spring rod 55 penetrates in the connecting portion.

[0040] Specifically, when the optical cable preform 7 penetrates in the clamping plate A4 and the clamping plate B54, the connecting portion at the top of the clamping plate B54 is manually pulled to move on the spring rod 55, the elastic potential energy of the spring on the spring rod 55 is used to apply pressure on the connecting portion, and after the hand is released, the one end of the optical cable preform 7 can be clamped, thereby ensuring the fixed length of the one end of the optical cable preform 7 and keeping a single variable.

[0041] As an embodiment of the present application, the horizontal cross bar 51 is sleeved with an extension rod 52 away from one end of the support plate 3, and a pin shaft B53 is fixed on the top surface of the extension rod 52; the extension rod 52 is slidingly connected to the horizontal cross bar 51 through the pin shaft B53.

[0042] Specifically, the length of the horizontal cross bar 51 can be extended by the extension rod 52 sliding on the horizontal cross bar 51, and the pin shaft B53 provided on the top of the extension rod 52 can be fixed after the extension rod 52 is adjusted by cooperating with a nut.

[0043] As an embodiment of the present application, the clamping plate A4 and the clamping plate B54 are spliced up and down, and the clamping plate A4 and the clamping plate B54 are provided with abutting blocks inside; the abutting blocks inside the clamping plate A4 and the abutting blocks inside the clamping plate B54 are alternately arranged up and down, and the height of the abutting blocks inside the clamping plate A4 is lower than that of the abutting blocks inside the clamping plate B54.

[0044] Specifically, the clamping plate A4 and the clamping plate B54 are spliced up and down, as shown in the accompanying drawings, and the abutting blocks inside are also alternately arranged up and down, which can press one end of the lead-in optical cable preform 7 penetrating between the clamping plate A4 and the clamping plate B54, thereby realizing the positioning effect, wherein the abutting blocks are made of rubber material. Figure 4

[0045] Working principle: In the prior art, other mechanical performance tests of the lead-in optical cable preform end assembly require a tensile machine, and the operation is relatively standardized; the drop test is relatively simple, and the current test device does not have a scale, so it is impossible to control a single variable during the drop test, thereby causing large test errors and low result accuracy, and the clamp for fixing the lead-in optical cable causes large wear of the sheath of the lead-in optical cable; when the device is used, first, the bearing plates 11 on both sides of the base 1 are separated from the base 1, and the bearing plates 11 are expanded to the sides by means of the hinges 13 and are laid flat on the ground, thereby playing a supporting effect; then, an operator rotates the clamping plate A4, and makes the clamping plate A4 and the horizontal cross bar 51 from parallel to the support frame 2 to 90° with the support frame 2; after the clamping plate A4, the horizontal cross bar 51 and the support frame 2 are at 90°, the operator slides the clamping plate A4 and the horizontal cross bar 51 backward, so that they are fixed on the bearing plate 3, and the metal impact plate 6 in the base 1 is taken out and clamped on the base 1; then, the lead-in optical cable preform 7 is taken out artificially, and a section penetrating between the clamping plate A4 and the clamping plate B54 is led out, and the led-out section is attached to the bottom of the horizontal cross bar 51; then, the hand is released, and the led-out end of the lead-in optical cable preform 7 will swing around the part fixed on the clamping plate A4 and the clamping plate B54 under the action of gravity, and will impact on the metal impact plate 6 under the action of inertial force; specifically, the led-out section of the lead-in optical cable preform 7 is 2 meters, and the end of the lead-in optical cable preform 7 is lifted to the bottom of the horizontal cross bar 51; then, the lead-in optical cable preform 7 is freely dropped, and the drop test is completed after being repeated 8 times; in the device, the steel ruler 21 is arranged on both sides of the support frame 2, which can ensure that the falling height of the lead-in optical cable is consistent and adjustable, so that the result error of the repeated test is relatively small, and the accuracy is ensured.

[0046] ​In the description of the specification, the description of the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0047] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A drop test apparatus for introducing a cable preform end assembly, characterized by: It include base (1), both sides of base (1) bottom end are hinged with bearing plate (11) through hinge (13), one end of base (1) top is fixedly connected with support frame (2), and the top of support frame (2) is fixedly connected with object bearing plate (3), the side of support frame (2) is embeddedly connected with steel ruler (21), one end of object bearing plate (3) is fixedly connected with clamping plate A (4), and one side of clamping plate A (4) is movably connected with clamping plate B (54), one end of clamping plate A (4) away from object bearing plate (3) is fixedly connected with horizontal cross bar (51), and clamping plate B (54) is movably connected on horizontal cross bar (51), the middle of base (1) is clamped with metal impact plate (6), and metal impact plate (6) is parallel with support frame (2), the top of object bearing plate (3) is used for carrying into optical cable prefabricated part (7), and one end of optical cable prefabricated part (7) penetrates clamping plate A (4), clamping plate B (54). Base (1) is provided as P type structure, and the receiving groove (14) is formed in base (1); the clamping block A (12) is arranged on base (1) corresponding to metal impact plate (6), and metal impact plate (6) is clamped in the inner side of clamping block A (12). The clamping groove (15) is formed in one end of base (1) away from metal impact plate (6), and the clamping block B (17) corresponding to clamping groove (15) is fixedly connected on bearing plate (11); bearing plate (11) is clamped in clamping groove (15) through clamping block B (17). The movable slot (18) is formed in one end of base (1) corresponding to clamping groove (15), and the extrusion plate (16) is movably connected in movable slot (18); the pressing block is fixedly connected on the inner side of extrusion plate (16), and the pressing block is movably connected in clamping groove (15). The connecting shaft (42) is fixedly connected on one end of clamping plate A (4), and the connecting shaft (42) is respectively located on both ends of clamping plate A (4) with horizontal cross bar (51); the roller (41) is rotatably connected on the top of one end of clamping plate A (4) close to object bearing plate (3), and the roller (41) is used for guiding optical cable prefabricated part (7).

2. A drop test apparatus for a cable-preform end assembly as defined in claim 1, wherein: The sliding groove (31) is formed in one end of object bearing plate (3) close to clamping plate A (4), and the connecting shaft (42) is slidably connected in sliding groove (31); the sliding groove (31) penetrates object bearing plate (3) on both sides and bottom side.

3. The drop test device for a prefabricated terminal assembly of an optical fiber cable according to claim 2, characterized in that: The pin shaft A (44) and the clamping plate (43) are fixedly connected on both sides of connecting shaft (42); the pin shaft A (44) and the clamping plate (43) are slidably connected in sliding groove (31); the clamping plate (43) is provided as L type structure.

4. A drop test apparatus for a cable-preform termination assembly as defined in claim 3, wherein: The notch is formed in horizontal cross bar (51) corresponding to clamping plate B (54), and the spring rod (55) arranged horizontally is fixedly connected in the notch; the connecting part is fixedly connected on the top of one end of clamping plate B (54), and the connecting part penetrates in the notch; the spring rod (55) penetrates in the connecting part.

5. A drop test apparatus for a cable-preform termination assembly as defined in claim 4, wherein: The horizontal crossbar (51) is sleeved with an extension rod (52) at one end away from the object supporting plate (3), and the top surface of the extension rod (52) is fixedly connected with a pin shaft B (53); the extension rod (52) is slidingly connected with the horizontal crossbar (51) through the pin shaft B (53).

6. A drop test apparatus for a cable-preform termination assembly as defined in claim 5, wherein: The clamping plate A (4) and the clamping plate B (54) are spliced up and down, and the clamping plate A (4) and the clamping plate B (54) are provided with abutting blocks in the inner portions; the abutting blocks in the clamping plate A (4) and the clamping plate B (54) are alternately arranged up and down, and the height of the abutting block in the clamping plate A (4) is lower than that of the abutting block in the clamping plate B (54).

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