Perpendicularity detection device for constructional engineering

Abstract

The invention relates to the technical field of building measurement, in particular to a building engineering perpendicularity detection device. The device comprises a device body, the device body comprises a body ring arranged on the periphery of the building supporting column, and the body ring is provided with an inner ring face opposite to the outer wall of the building supporting column; a moving mechanism is arranged on the inner ring face and comprises a moving frame, a pay-off frame is arranged on the moving frame, and a plumb bob used for detecting the perpendicularity of a building is arranged on the pay-off frame. A transmission part is arranged between the moving frame and the pay-off frame, and the moving frame is used for moving in the axial direction of the building supporting column so that the transmission part can drive the pay-off frame to rotate to take up and pay off the plumb bob. Compared with the prior art, the plumb bob is synchronously wound and unwound through movement of the moving mechanism, the length of the wound and unwound plumb bob can be rapidly adjusted according to different heights, and workers can conveniently measure the perpendicularity of the outer wall of the building supporting column.

Description

Technical Field

[0001] The invention relates to the technical field of building measurement, in particular to a device for detecting verticality of a building project. Background Art

[0002] Verticality refers to the degree of vertical deviation of a component relative to its designed position. It is one of the important indicators for measuring the quality and safety of building structures. Verticality detection in construction projects refers to the process of measuring and verifying the verticality of vertical components such as building support columns and walls in buildings or structures.

[0003] The plumb bob method is a common method for detecting building verticality. It uses the principle of gravity to determine whether an object is vertical. This method is widely used in the field of construction engineering.

[0004] When inspecting building support columns in construction projects, it is necessary to inspect their verticality. However, when existing inspection devices measure building support columns, they need to use an adjustment frame to send the inspection device to a high place for measurement. The process is relatively cumbersome and affects the efficiency of column monitoring. Summary of the invention

[0005] The invention provides a construction engineering verticality detection device, which can overcome the defect of complicated verticality detection of building support columns in the prior art.

[0006] A device for detecting verticality of a construction project according to the present invention comprises a device body, the device body comprises a main body ring for being arranged on the periphery of a building support column, the main body ring has an inner ring surface opposite to the outer wall of the building support column; a moving mechanism is arranged at the inner ring surface, the moving mechanism comprises a moving frame, a pay-off frame is arranged at the moving frame, a plumb bob for detecting the verticality of the building is arranged at the pay-off frame; a transmission member is arranged between the moving frame and the pay-off frame, the moving frame is used to move axially along the building support column, so that the transmission member drives the pay-off frame to rotate to retract and release the plumb bob.

[0007] Compared with the prior art, the wire bob is retracted and released synchronously by moving the mobile mechanism, and the length of the retracted and released wire of the wire bob can be quickly adjusted according to different heights, which is convenient for workers to measure the verticality of the outer wall of the building support column.

[0008] Preferably, the main body ring includes a first arc-shaped member and a second arc-shaped member that are detachably connected, and the first arc-shaped member and the second arc-shaped member both have inner arc surfaces corresponding to the outer wall of the building support column.

[0009] In the present invention, when installing the main body ring, the staff can disassemble and install the first arc-shaped member and the second arc-shaped member respectively, thereby improving the convenience of installation. Moreover, after the main body ring is disassembled, it occupies a smaller area, which is convenient for transportation and production.

[0010] Preferably, the moving mechanism also includes a support base arranged at the outer wall of the inner arc surface, and the support base is provided with a threaded column perpendicular to the axial direction of the building support column on the surface opposite to the inner arc surface, a first adjustment cavity is opened at the end of the threaded column, a first adjustment member is slidably arranged in the first adjustment cavity, and a mounting seat for installing the moving frame is provided at the end of the first adjustment member, a control member is threadedly connected to the outer wall of the threaded column, and a first clamping spring is provided on the outer wall of the threaded column between the control member and the mounting seat for pushing the moving frame to press against the outer wall of the building support column.

[0011] In the present invention, the first clamping spring on the threaded column will push the mounting seat to move toward the building support column, so that the movable frame is in close contact with the outer wall of the building support column, thereby improving the stability of the device in the vertical direction of the building support column. In addition, the elastic force of the first clamping spring can be adjusted by rotating the control part. While ensuring the stability of the device movement, measurements can be performed on building support columns of different diameters, thereby improving the adaptability of the device.

[0012] Preferably, the mobile frame includes a mobile shell for connecting to the mounting base, the mobile shell having a accommodating cavity, a double-headed motor being arranged in the accommodating cavity, a driving shaft extending in the width direction being arranged at both driving ends of the double-headed motor, and a driving wheel being arranged at the end of the driving shaft for contacting the outer wall of the building support column.

[0013] In the present invention, the double-headed motor drives the driving shaft to rotate, and drives the driving wheel attached to the outer wall of the building support column to rotate, thereby driving the device body to move in the height direction of the outer wall of the building support column.

[0014] Preferably, the pay-off frame includes a transmission shaft rotatably arranged at the bottom of the movable housing, and the transmission member is respectively connected to the transmission shaft and the drive shaft, so that the drive shaft rotates and drives the transmission shaft to rotate.

[0015] In the present invention, the transmission member drives the driving shaft to rotate, thereby retracting and paying out the wire by the bobbin on the pay-off frame.

[0016] Preferably, an annular channel is provided at the bottom of the first arc-shaped member and the second arc-shaped member, an annular moving member is provided in the annular channel, a driving motor is provided at the top of the first arc-shaped member, a driving end of the driving motor is meshedly connected with the annular moving member so as to drive the annular moving member to slide in the annular channel, a protruding block is provided at the bottom of the annular moving member, a guiding mechanism is provided at the protruding block, and the guiding mechanism is used to guide the retracting and releasing line of the hanging wire bob.

[0017] In the present invention, the guide mechanism pulls the plumb bob to different circumferential positions of the outer wall of the building support column, thereby achieving multi-point measurement of the circumferential direction of the building support column and improving the accuracy of the measurement data of the device.

[0018] Preferably, the guiding mechanism comprises a fixed block arranged at the outer wall of the protruding block, the fixed block having a second adjusting cavity, a second adjusting member slidingly arranged in the second adjusting cavity, the second adjusting cavity being provided with a second clamping spring for clamping the second adjusting member against the outer wall of the building support column, and a guide hole for sliding the retracting and releasing line of the hanging wire bob being provided on the outer wall along the height direction.

[0019] In the present invention, the second adjusting member is fitted with the outer wall of the building support column, which not only allows the retracted and released line of the plumb bob to be close to the outer wall of the building support column after being guided by the guide hole, making it convenient for staff to detect the verticality, but also allows the second adjusting member to be autonomously adjusted according to the outer walls of the building support columns with different diameters, thereby improving the applicability of the device.

[0020] Preferably, the outer wall of the second adjusting member is provided with a rotating hole at one end of the building support column, and a rotating ball for contacting the outer wall of the building support column is rotatably provided in the rotating hole.

[0021] In the present invention, the rotating ball contacts the outer wall of the building support column, reducing the friction between the second adjusting member and the surface of the outer wall of the building support column, which neither affects the movement of the device in the height direction of the outer wall of the building support column, nor enables the second adjusting member to move along the circumference of the outer wall of the building support column.

[0022] Preferably, the pay-off rack also includes an adapting cylinder rotatably arranged on the outer wall of the transmission shaft, the wire bob is wound around the outer wall of the adapting cylinder, a reset disk is provided on the outer wall of the transmission shaft, the reset disk has a reset cavity, the adapting cylinder has a deep portion deep into the reset cavity, and a spring is provided in the reset cavity which elastically contacts the deep portion and enables the adapting cylinder to rotate and reset.

[0023] In the present invention, when the second adjusting member is reset, the mainspring in the reset chamber will push the deep-entering portion on the adapting tube to rotate in the line-retrieving direction, thereby realizing the autonomous adjustment of the length of the hanging bob during the circumferential movement.

[0024] Preferably, positioning grooves are provided on both sides of the outer wall of the second adjusting member, a guide rod is provided in the positioning groove, a positioning member is slidably provided on the outer wall of the guide rod, a positioning spring is provided on the outer wall of the guide rod for pushing the positioning member to slide in the direction of the guide hole and limit the position of the retracting and releasing line of the hanging bob, an extension plate is provided on the outer wall of the mounting seat, the extension plate has a guide block, and an extrusion rod is provided on the upper part of the outer wall of the positioning member for sliding contact with the guide block and causing the positioning member to slide in the direction relative to the guide hole.

[0025] In the present invention, after the second adjusting member is reset, the guide block on the extension plate will squeeze the squeezing rod, so that the positioning member cancels the limitation on the retracting and releasing line of the hanging bob. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the device body in Example 1; Figure 2is a schematic diagram of the moving mechanism in Example 1; Figure 3 is a schematic diagram of a side cross-sectional view of the device body in Example 1; Figure 4 is a schematic diagram of a top cross-sectional view of the device body in Example 1; Figure 5 is a schematic diagram of a side cross-sectional view of the movable housing in Example 1; Figure 6 It is a schematic diagram of the explosive structure of the pay-off frame in Example 1; Figure 7 is a schematic diagram of the reset disk in Example 1; Figure 8 is a schematic diagram of the guide mechanism in Example 1; Fig. 9 This is a schematic diagram of the explosive structure of the guide mechanism in Example 1. DETAILED DESCRIPTION

[0027] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the embodiments. It should be understood that the embodiments are only for explaining the present invention and are not intended to limit it.

[0028] Example 1 like Figure 1-5 As shown, this embodiment provides a verticality detection device for a construction project, which includes a device body 100, the device body 100 includes a main body ring 110 for being arranged on the periphery of a building support column, the main body ring 110 has an inner ring surface 111 opposite to the outer wall of the building support column; a moving mechanism 120 is provided at the inner ring surface 111, the moving mechanism 120 includes a moving frame 210, a pay-off frame 310 is provided at the moving frame 210, and a plumb bob 320 for detecting the verticality of the building is provided at the pay-off frame 310; a transmission member 510 is provided between the moving frame 210 and the pay-off frame 310, the moving frame 210 is used to move axially along the building support column, so that the transmission member 510 drives the pay-off frame 310 to rotate to retract and release the plumb bob 320.

[0029] The present invention discloses a device for detecting verticality of a construction project, which drives a main body ring 110 to move to any height of the outer wall of a building support column through a moving mechanism 120. During this period, a transmission member 510 will retract and release a plumb bob 320 on a pay-out frame 310 according to the moving distance of the moving frame 210. Compared with the prior art, the plumb bob 320 can be retracted and released synchronously through the movement of the moving mechanism 120, and the length of the retracted and released plumb bob 320 can be quickly adjusted according to different heights, so that the staff can measure the verticality of the outer wall of the building support column conveniently.

[0030] Combination Figure 1-3As shown, in this embodiment, the main body ring 110 includes a first arc-shaped member 220 and a second arc-shaped member 230 that are detachably connected, and the first arc-shaped member 220 and the second arc-shaped member 230 both have an inner arc surface 240 corresponding to the outer wall of the building support column; the moving mechanism 120 also includes a support base 330 arranged at the outer wall of the inner arc surface 240, and the support base 330 is located on the opposite surface of the inner arc surface 240 and is provided with a threaded column 331 perpendicular to the axial direction of the building support column, and a first adjustment cavity 332 is opened at the end of the threaded column 331, and a first adjustment member 333 is slidably provided in the first adjustment cavity 332, and a mounting seat 334 for mounting the moving frame 210 is provided at the end of the first adjustment member 333, and a control member 335 is threadedly connected to the outer wall of the threaded column 331, and a first clamping spring 336 for pushing the moving frame 210 to press against the outer wall of the building support column is provided on the outer wall of the threaded column 331 between the control member 335 and the mounting seat 334.

[0031] Through the above structure, when the staff installs the main ring 110, they can disassemble and install the first arc member 220 and the second arc member 230 respectively, thereby improving the convenience of installation. Moreover, after the main ring 110 is disassembled, it occupies a smaller area, which is convenient for transportation and production. At the same time, the first clamping spring 336 on the threaded column 331 will push the mounting seat 334 to move toward the building support column, so that the movable frame 210 is in close contact with the outer wall of the building support column, thereby improving the stability of the device in the vertical direction of the building support column. Moreover, the elastic force of the first clamping spring 336 can be adjusted by rotating the control member 335. While ensuring the stability of the movement of the device, it can be measured on building support columns with different diameters, thereby improving the adaptability of the device.

[0032] Combination Figure 2-5 As shown, in this embodiment, the mobile frame 210 includes a mobile shell 520 for connecting to the mounting seat 334, the mobile shell 520 has a accommodating cavity 521, a double-headed motor 522 is arranged in the accommodating cavity 521, and the driving ends of both ends of the double-headed motor 522 are provided with a driving shaft 523 extending along the width direction, and the end of the driving shaft 523 is provided with a driving wheel 524 for contacting the outer wall of the building support column; the wire pay-off frame 310 includes a transmission shaft 530 rotatably arranged at the bottom of the mobile shell 520, and the transmission member 510 is respectively connected to the transmission shaft 530 and the driving shaft 523, so that the driving shaft 523 rotates, driving the transmission shaft 530 to rotate.

[0033] Through the above structure, the staff remotely controls the double-headed motor 522 to start through the controller. The double-headed motor 522 will drive the driving shaft 523 to rotate, and drive the driving wheel 524 attached to the outer wall of the building support column to rotate, thereby driving the device body 100 to move in the height direction of the outer wall of the building support column; at the same time, the transmission member 510 will drive the driving shaft 523 to rotate, thereby retracting and releasing the wire to the hanging wire bob 320 on the wire pay-off frame 310.

[0034] Combination Figure 2-9 As shown, in this embodiment, an annular channel 340 is provided at the bottom of the first arc-shaped member 220 and the second arc-shaped member 230, an annular moving member 350 is provided in the annular channel 340, a driving motor 250 is provided at the top of the first arc-shaped member 220, and the driving end of the driving motor 250 is meshed and connected with the annular moving member 350 so as to drive the annular moving member 350 to slide in the annular channel 340, a protruding block 360 is provided at the bottom of the annular moving member 350, and a guiding mechanism 370 is provided at the protruding block 360, and the guiding mechanism 370 is used to guide the wire bob 320 to retract and release the wire; the guiding mechanism 370 includes a A fixed block 810 is provided at the outer wall of the protruding block 360, and the fixed block 810 has a second adjusting cavity 820, in which a second adjusting member 830 is slidably provided, and the second adjusting cavity 820 is provided with a second clamping spring 910 for making the second adjusting member 830 press against the outer wall of the building support column, and the outer wall of the second adjusting member 830 is provided with a guide hole 840 along the height direction for the sliding of the retracting and releasing line of the plumb bob 320; the outer wall of the second adjusting member 830 is provided with a rotating hole 920 at one end of the building support column, and a rotating ball 930 for contacting the outer wall of the building support column is rotatably provided in the rotating hole 920.

[0035] Through the above structure, after the staff adjusts the device to a suitable height, the remote control drive motor 250 is started, so that the annular moving part 350 slides in the annular channel 340, so that the guide mechanism 370 moves along the circumference of the outer wall of the building support column, and the guide mechanism 370 pulls the plumb bob 320 to reach different circumferential positions of the outer wall of the building support column, thereby realizing multi-point measurement of the circumferential direction of the building support column and improving the accuracy of the device measurement data; at the same time, the second adjusting member 830 slides in the second adjusting cavity 820 in the fixed block 810 through the second clamping spring 910, which can make the second adjusting member 830 slide in the second adjusting cavity 820 in the fixed block 810 The joint part 830 fits with the outer wall of the building support column, which makes the retracted and released line of the plumb bob 320 guided by the guide hole 840 close to the outer wall of the building support column, making it convenient for the staff to check the verticality, and the second adjusting part 830 can be adjusted autonomously according to the outer wall of the building support column with different diameters, thereby improving the applicability of the device; the rotating ball 930 contacts the outer wall of the building support column, reducing the friction between the second adjusting part 830 and the surface of the outer wall of the building support column, which does not affect the movement of the device in the height direction of the outer wall of the building support column, and enables the second adjusting part 830 to move along the circumference of the outer wall of the building support column.

[0036] Combination Figure 3-9As shown, in this embodiment, the pay-off frame 310 also includes an adapting cylinder 610 rotatably arranged on the outer wall of the transmission shaft 530, the plumb bob 320 is wound around the outer wall of the adapting cylinder 610, the outer wall of the transmission shaft 530 is provided with a reset disk 620, the reset disk 620 has a reset cavity 630, the adapting cylinder 610 has a deep portion 710 deep into the reset cavity 630, and the reset cavity 630 is provided with a spring 640 that elastically contacts the deep portion 710 and enables the adapting cylinder 610 to rotate and reset; the outer wall of the second adjusting member 830 is provided with positioning grooves 850 on both sides. A guide rod 940 is provided in the positioning groove 850, a positioning piece 950 is slidably provided on the outer wall of the guide rod 940, a positioning spring 960 is provided on the outer wall of the guide rod 940 for pushing the positioning piece 950 to slide in the direction of the guide hole 840 and limiting the position of the retracting and releasing line of the plumb bob 320, an extension plate 860 is provided on the outer wall of the mounting seat 334, the extension plate 860 has a guide block 870, and an extrusion rod 880 is provided on the upper part of the outer wall of the positioning piece 950 for sliding contact with the guide block 870 and causing the positioning piece 950 to slide in the direction relative to the guide hole 840.

[0037] Taking into account that when the plumb bob 320 moves circumferentially along the outer wall of the support column, the length of the plumb bob 320 itself will change, so that the plumb bob 320 is lifted up by a part of its length, thereby affecting the detection of the entire outer wall of the support column, through the above structure, when the second adjusting member 830 moves circumferentially, it will pull the adaption tube 610 on the outer wall of the transmission shaft 530 to rotate, thereby releasing the plumb bob 320 wound on the outer wall of the adaption tube 610, and when the second adjusting member 830 is reset, the spring 640 in the reset chamber 630 will push the deep portion 710 on the adaption tube 610 to rotate in the direction of taking up the line, thereby realizing the circumferential adjustment of the plumb bob 320 Autonomous adjustment of length during movement; at the same time, when the second adjusting member 830 moves circumferentially, the positioning spring 960 on the guide rod 940 will push the positioning member 950 to slide in the direction of the guide hole 840, thereby clamping and fixing the retracting and releasing line of the wire bob 320 sliding in the guide hole 840, avoiding changes in the length of the retracting and releasing line of the wire bob 320 located inside the guide hole 840 and at the lower end, thereby further improving the measurement accuracy of the device, and after the second adjusting member 830 is reset, the guide block 870 on the extension plate 860 will squeeze the extrusion rod 880, so that the positioning member 950 cancels the limit on the retracting and releasing line of the wire bob 320.

[0038] It is easy to understand that those skilled in the art can combine, split, reorganize, etc. the embodiments of the present application to obtain other embodiments based on one or several embodiments provided in the present application, and these embodiments do not exceed the protection scope of the present application.

[0039] The present invention and its implementation methods are described schematically above, and the description is not restrictive. The embodiments shown in the embodiments are only part of the implementation methods of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by the embodiments and designs a structure and an implementation method similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A construction engineering verticality detection device, characterized in that: The device comprises a device body (100), wherein the device body (100) comprises a main body ring (110) for being arranged on the periphery of a building support column, and the main body ring (110) has an inner ring surface (111) opposite to the outer wall of the building support column; A moving mechanism (120) is provided at the inner annular surface (111), the moving mechanism (120) comprises a moving frame (210), a wire pay-off frame (310) is provided at the moving frame (210), and a plumb bob (320) for detecting the verticality of the building is provided at the wire pay-off frame (310); A transmission member (510) is provided between the movable frame (210) and the pay-off frame (310), and the movable frame (210) is used to move axially along the building support column, so that the transmission member (510) drives the pay-off frame (310) to rotate to retract and release the plumb bob (320).

2. A construction engineering verticality detection device according to claim 1, characterized in that: The main body ring (110) comprises a first arc-shaped member (220) and a second arc-shaped member (230) which are detachably connected, and both the first arc-shaped member (220) and the second arc-shaped member (230) have inner arc surfaces (240) corresponding to the outer walls of the building support columns.

3. A construction engineering verticality detection device according to claim 2, characterized in that: The moving mechanism (120) further comprises a support base (330) arranged at the outer wall of the inner arc surface (240); the support base (330) is provided with a threaded column (331) perpendicular to the axial direction of the building support column on the surface opposite to the inner arc surface (240); a first adjustment cavity (332) is provided at the end of the threaded column (331); a first adjustment member (333) is slidably provided in the first adjustment cavity (332); a mounting seat (334) for mounting the moving frame (210) is provided at the end of the first adjustment member (333); a control member (335) is threadedly connected to the outer wall of the threaded column (331); and a first pressing spring (336) for pushing the moving frame (210) to press against the outer wall of the building support column is provided on the outer wall of the threaded column (331) between the control member (335) and the mounting seat (334).

4. A construction engineering verticality detection device according to claim 3, characterized in that: The movable frame (210) comprises a movable housing (520) for connecting to a mounting seat (334); the movable housing (520) comprises a housing cavity (521); a double-headed motor (522) is arranged in the housing cavity (521); driving ends at both ends of the double-headed motor (522) are provided with a driving shaft (523) extending in the width direction; and the end of the driving shaft (523) is provided with a driving wheel (524) for contacting the outer wall of a building support column.

5. A construction engineering verticality detection device according to claim 1 or 4, characterized in that: The pay-off frame (310) comprises a transmission shaft (530) rotatably arranged at the bottom of the movable housing (520), and the transmission member (510) is respectively connected to the transmission shaft (530) and the driving shaft (523), so that the driving shaft (523) rotates, thereby driving the transmission shaft (530) to rotate.

6. A construction engineering verticality detection device according to claim 1, characterized in that: An annular channel (340) is provided at the bottom of the first arc-shaped member (220) and the second arc-shaped member (230), an annular moving member (350) is provided in the annular channel (340), a driving motor (250) is provided at the top of the first arc-shaped member (220), a driving end of the driving motor (250) is meshedly connected with the annular moving member (350), so that the annular moving member (350) is driven to slide in the annular channel (340), a protruding block (360) is provided at the bottom of the annular moving member (350), a guiding mechanism (370) is provided at the protruding block (360), and the guiding mechanism (370) is used to guide the retracting and releasing line of the plumb bob (320).

7. A construction engineering verticality detection device according to claim 6, characterized in that: The guide mechanism (370) comprises a fixed block (810) arranged at the outer wall of the protruding block (360), the fixed block (810) having a second adjustment cavity (820), a second adjustment member (830) being slidably arranged in the second adjustment cavity (820), the second adjustment cavity (820) being provided with a second pressing spring (910) for pressing the second adjustment member (830) against the outer wall of the building support column, and a guide hole (840) for sliding the retracting and releasing wire of the plumb bob (320) being provided on the outer wall along the height direction.

8. A construction engineering verticality detection device according to claim 7, characterized in that: The outer wall of the second adjusting member (830) is provided with a rotation hole (920) at one end of the building support column, and a rotation ball (930) is rotatably provided in the rotation hole (920) for contacting the outer wall of the building support column.

9. A construction engineering verticality detection device according to claim 1 or 5, characterized in that: The pay-off frame (310) further comprises an adapting tube (610) rotatably arranged on the outer wall of the transmission shaft (530), the plumb bob (320) is wound around the outer wall of the adapting tube (610), a reset disk (620) is arranged on the outer wall of the transmission shaft (530), the reset disk (620) has a reset cavity (630), the adapting tube (610) has a deep-reaching portion (710) that penetrates deep into the reset cavity (630), and a spring (640) is arranged in the reset cavity (630) that elastically contacts the deep-reaching portion (710) and enables the adapting tube (610) to rotate and reset.

10. A construction engineering verticality detection device according to claim 3 or 7, characterized in that: Positioning grooves (850) are provided on both sides of the outer wall of the second adjusting member (830), a guide rod (940) is provided in the positioning groove (850), a positioning member (950) is slidably provided on the outer wall of the guide rod (940), a positioning spring (960) is provided on the outer wall of the guide rod (940) for pushing the positioning member (950) to slide in the direction of the guide hole (840) and limiting and fixing the retracting and releasing line of the plumb bob (320), an extension plate (860) is provided on the outer wall of the mounting seat (334), the extension plate (860) has a guide block (870), and an extrusion rod (880) is provided on the upper part of the outer wall of the positioning member (950) for slidingly contacting the guide block (870) and causing the positioning member (950) to slide in the direction relative to the guide hole (840).

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