Flatness laser measuring instrument for foundation engineering

Abstract

The invention provides a flatness laser measuring instrument for foundation engineering, and relates to the technical field of levelness measurement, and the flatness laser measuring instrument comprises a measuring instrument main body, a plurality of L-shaped connecting plates are welded around the periphery of a rotating ring, a driving ring is welded at the tail ends of the plurality of L-shaped connecting plates, a driving ring is rotatably mounted at the bottom of the driving ring, and a circle of finger shifting plates are welded around the periphery of the driving ring; an arc-shaped rack is slidably installed on one L-shaped connecting plate in a spring pushing mode, in the idle state, the arc-shaped rack is separated from the driving gear in a spaced mode, and in the using state, the arc-shaped rack slides towards the driving gear and is meshed with the driving gear. And a connecting rod is rotationally connected between the arc-shaped rack and the driving ring. The three threaded lifting rods can share one set of lifting driving mechanism for lifting driving, the situation that one set of lifting driving mechanism needs to be arranged for each threaded lifting rod can be omitted, the lifting driving mechanism can achieve three purposes, and the structure for leveling the measuring instrument can be simplified on the whole.

Description

Technical Field

[0001] The present invention relates to the technical field of levelness measurement, in particular to a flatness laser measuring instrument for foundation engineering. Background Art

[0002] During construction, the flatness of foundations must be measured in real time to ensure the support strength of subsequent buildings constructed on the foundations. Among the tools used to measure flatness, laser measuring instruments are the most widely used.

[0003] On existing laser measuring instruments, the threaded lifting mechanism used for leveling is mostly installed integrally at the bottom of the chassis. This means that when leveling the laser measuring instrument, one needs to insert one's hand into the cramped space between the chassis and the surface to be measured to rotate the threaded lifting mechanism forward and backward. This cramped space will block the hand's rotating movement, affecting the convenience of the leveling operation. Although some threaded lifting structures are installed through the chassis of the laser measuring instrument in the prior art, and the threaded lifting structure can be driven by twisting in the open space above the chassis, the threaded lifting structure is installed in multiple places around the laser measuring instrument. As a result, when the threaded lifting structure is turned away from the operator, the hand needs to be moved around the back of the laser measuring instrument to grasp and contact the threaded lifting structure to realize the twisting operation of the threaded lifting structure, which is still cumbersome and inconvenient to operate. Summary of the Invention

[0004] In view of this, the present invention provides a flatness laser measuring instrument for foundation engineering to solve the problem that when performing a rotary drive operation on a threaded lifting structure that is away from the worker, the hand needs to be transferred and placed around the back of the laser measuring instrument in order to grasp and contact the threaded lifting structure to realize the rotary operation of the threaded lifting structure, which is still cumbersome and inconvenient to operate.

[0005] The technical solution proposed by the present invention is: a flatness laser measuring instrument for foundation engineering, specifically comprising a measuring instrument body, wherein the bottom of the measuring instrument body is fixedly connected to a chassis; The outer edge of the chassis is slidably installed with three threaded lifting rods that are rotationally limited. The outer edge is slidably installed with three threaded rod sleeves that are rotationally installed. The threaded lifting rods are threadedly screwed into the threaded rod sleeves at the corresponding positions, and the bottom end of the threaded rod sleeve is fixedly installed with a driving gear; the outer periphery of the chassis is rotatably installed with a swivel, and multiple L-shaped connecting plates are welded around the outer periphery of the swivel, and the tail ends of the multiple L-shaped connecting plates are welded with driving rings. A driving ring is rotatably installed at the bottom of the driving ring, and a circle of finger shift plates is welded around the outer periphery of the driving ring; an arc-shaped rack is slidably installed on one of the L-shaped connecting plates in the form of a spring push. In the idle state, the arc-shaped rack is separated from the driving gear. In the use state, the arc-shaped rack slides toward the driving gear and meshes with the driving gear; a connecting rod is rotatably connected between the arc-shaped rack and the driving ring.

[0006] Furthermore, an L-shaped sliding part is welded to the middle position of the outer side of the arc-shaped rack. The L-shaped sliding part is composed of an L-shaped sliding rod and a square sliding sleeve welded to the head end of the L-shaped sliding rod. The tail end of the L-shaped sliding rod is welded and fixed to the arc-shaped rack. The square sliding sleeve slides with the horizontal plate section of the L-shaped connecting plate at the corresponding position. The spring for pushing the arc-shaped rack is installed on the horizontal plate section and is compressed and clamped between the swivel and the square sliding sleeve.

[0007] Furthermore, the head end of the connecting rod is rotatably connected to the L-shaped sliding rod, and the tail end is rotatably connected to the inner circumference of the driving ring.

[0008] Furthermore, three U-shaped limiters are welded around the top of the outer edge of the chassis. The U-shaped limiter consists of a limit ring and two L-shaped support rods symmetrically welded on the limit ring. The threaded lifting rod and the limit ring are slidably fitted together, and the tail ends of the two L-shaped support rods are welded and fixed to the chassis.

[0009] Furthermore, the inner circumference of the limiting ring is symmetrically integrally formed with two limiting protrusions, and the outer circumference of the threaded lifting rod is symmetrically provided with two strip-shaped sliding grooves adapted to the shape of the limiting protrusions, and the two limiting protrusions slide in correspondence with the two strip-shaped sliding grooves.

[0010] Furthermore, the swivel has a U-shaped cross-section structure and is provided with an annular track groove, which is rotatably engaged with the outer peripheral portion of the chassis.

[0011] Furthermore, a track ring groove is provided on the bottom side of the driving ring, and a guide ring adapted to the shape of the track ring groove is welded on the top of the driving ring, and the guide ring is rotatably matched with the track ring groove.

[0012] Furthermore, four vertical laser emitting heads are embedded in the upper half of the main shell of the measuring instrument in a cross-shaped symmetrical form, and the vertical laser emitting heads are used to emit vertical measuring laser marking lines.

[0013] Furthermore, two horizontal laser emitting heads are symmetrically embedded in the lower half of the main shell of the measuring instrument, and the horizontal laser emitting heads are used to emit horizontal measuring laser marking lines.

[0014] The present invention provides a flatness laser measuring instrument for foundation engineering, which has the following beneficial effects: 1. The three threaded rod sleeves and the three threaded lifting rods together constitute three sets of threaded lifting structures for leveling the measuring instrument. The three sets of threaded lifting structures are arranged through the chassis and are driven by a driving ring arranged in the open space around the chassis. In this way, by directly twisting the driving ring forward and backward in the open space around the chassis, the three sets of threaded lifting structures can be driven to rise and fall and slide respectively to complete the leveling of the entire measuring instrument. Compared with the existing technology in which the threaded lifting structure is completely arranged at the bottom of the chassis, this technology can save the trouble of having to reach into the cramped space between the chassis and the plane to be measured in order to contact the threaded lifting structure to drive the threaded lifting structure for lifting and lowering when leveling the measuring instrument. It can also avoid the cramped space from blocking and interfering with the operation of the hand driving the threaded lifting structure, thereby helping to improve the convenience of the leveling operation of the measuring instrument.

[0015] 2. The drive ring and the arc-shaped rack together form a lifting drive mechanism; by rotating the drive ring forward and backward, the arc-shaped rack can be adjusted to a position that meshes with the three drive gears, and the three threaded lifting rods are lifted and lowered in turn to complete the leveling operation of the measuring instrument. This allows the three threaded lifting rods to share a set of lifting drive mechanisms for lifting and lowering, eliminating the need to configure a set of lifting drive mechanisms for each of the three threaded lifting rods, so that the lifting drive mechanism can serve three purposes, which helps to simplify the structure for leveling the measuring instrument as a whole.

[0016] 3. The lifting drive mechanism is a mechanism that drives the three sets of threaded lifting structures to perform common lifting and adjustment. The driving ring is a component of the lifting drive mechanism. The driving ring is a circular ring structure and is installed in the open space around the chassis. This arrangement makes it possible to hold the hand on the convenient holding part of the driving ring and twist the driving ring back and forth to implement it no matter what orientation the threaded lifting structure is in when performing the lifting and lowering drive. Compared with the existing technology that lacks a mechanism that can drive the three sets of threaded lifting structures to perform common lifting and adjustment, this can eliminate the trouble of the staff turning their hands around the back of the measuring instrument and contacting the threaded lifting structure to perform the lifting and lowering drive of the threaded lifting structure on the back side of the measuring instrument. The operation is simple and convenient.

[0017] Fourth, the drive ring is rotatably mounted at the bottom of the drive ring and close to the drive ring. This allows the hand to hold the drive ring and perform reciprocating twisting and driving, while at the same time, pushing or releasing the finger plate with the finger to complete the meshing transmission and separation and decoupling operations of the arc-shaped rack and the drive gear. This allows the reciprocating drive operation of the drive ring and the meshing transmission and separation and decoupling operations of the arc-shaped rack and the drive gear to be performed with one hand without the need for significant movement of the hand, thereby saving the use of both hands and making the leveling operation of the measuring instrument simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments are briefly introduced below.

[0019] The drawings described below only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0020] In the attached figure: Figure 1 Shows a schematic structural diagram of the present invention as a whole; Figure 2 A schematic diagram showing the bottom side view of the present invention as a whole is shown; Figure 3 The present invention shows Figure 2 A schematic diagram of the enlarged structure of part A; Figure 4 A schematic diagram showing the disassembly state of the threaded lifting rod and the threaded rod sleeve in the present invention is shown; Figure 5 A diagram showing the assembly relationship between the threaded lifting rod, the U-shaped limiting member, and the threaded rod sleeve in the present invention; Figure 6 A schematic diagram of a half-section structure of the rotating ring, the driving ring and the driving circle in the present invention is shown; Figure 7 A schematic diagram showing the drive ring in a half-cut state and the drive ring being separated and disassembled in the present invention is shown; Figure 8 The figure shows a schematic structural diagram of the arc-shaped rack in the present invention.

[0021] List of reference numerals: 1. Measuring instrument body; 101. Chassis; 102. L-shaped stopper; 1021. L-shaped support rod; 1022. Stop ring; 1023. Stop protrusion; 103. Threaded lifting rod; 1031. Strip-shaped slide; 104. Threaded rod sleeve; 1041. Drive gear; 2. Erect the laser transmitter head; 3. Horizontal laser transmitter head; 4. Swivel; 401. L-shaped connecting plate; 5. Drive ring; 501. Track ring groove; 6. Driving ring; 601. Finger plate; 602. Guide ring; 7. Arc-shaped rack; 701. L-shaped sliding member; 7011. L-shaped sliding rod; 7012. Square sliding sleeve; 702. Connecting rod. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The following is an embodiment of the present invention, please refer to Figures 1 to 8 : This embodiment provides a flatness laser measuring instrument for foundation engineering, comprising a measuring instrument body 1, with a chassis 101 fixedly connected to the bottom of the measuring instrument body 1; The outer edge of the chassis 101 is slidably mounted with three threaded lifting rods 103 that are rotationally limited. The outer edge is rotatably mounted with three threaded rod sleeves 104. The threaded lifting rods 103 are screwed together with the threaded rod sleeves 104 at the corresponding positions. The bottom end of the threaded rod sleeve 104 is fixedly mounted with a driving gear 1041. The outer periphery of the chassis 101 is rotatably mounted with a swivel 4. The outer periphery of the swivel 4 is welded with multiple L-shaped connecting plates 401. A driving ring 5 is welded to the tail end of the plate 401, and a driving circle 6 is rotatably installed at the bottom of the driving ring 5. A circle of finger shift plate 601 is welded around the outer periphery of the driving circle 6; an arc-shaped rack 7 is slidably installed on an L-shaped connecting plate 401 in the form of a spring push. In the idle state, the arc-shaped rack 7 is separated from the driving gear 1041. In the use state, the arc-shaped rack 7 slides toward the driving gear 1041 and engages with the driving gear 1041; a connecting rod 702 is rotatably connected between the arc-shaped rack 7 and the driving circle 6.

[0024] Preferably, an L-shaped sliding member 701 (such as Figure 7 As shown in the figure), the L-shaped sliding member 701 is composed of an L-shaped sliding rod 7011 and a square sliding sleeve 7012 welded to the head end of the L-shaped sliding rod 7011. The tail end of the L-shaped sliding rod 7011 is welded and fixed to the arc-shaped rack 7. The square sliding sleeve 7012 slides with the horizontal plate section of the L-shaped connecting plate 401 at the corresponding position. The spring that pushes the arc-shaped rack 7 is installed on the horizontal plate section and is compressed and clamped between the swivel 4 and the square sliding sleeve 7012.

[0025] Preferably, the head end of the connecting rod 702 is rotatably connected to the L-shaped sliding rod 7011 , and the tail end is rotatably connected to the inner circumference of the driving ring 6 .

[0026] Preferably, three U-shaped limiting members 102 are welded around the top of the outer edge of the chassis 101. The U-shaped limiting member 102 is composed of a limiting ring 1022 and two L-shaped support rods 1021 symmetrically welded on the limiting ring 1022 (as shown in FIG. Figure 5 As shown), the threaded lifting rod 103 and the limiting ring 1022 are slidably matched, and the tail ends of the two L-shaped support rods 1021 are welded and fixed to the chassis 101.

[0027] Preferably, two limiting protrusions 1023 are symmetrically formed on the inner circumference of the limiting ring 1022, and two strip-shaped sliding grooves 1031 that are symmetrically adapted to the shape of the limiting protrusions 1023 are opened on the outer circumference of the threaded lifting rod 103. The two limiting protrusions 1023 slide in correspondence with the two strip-shaped sliding grooves 1031.

[0028] Preferably, the swivel 4 has a U-shaped cross-section structure and is provided with an annular track groove, which is rotatably engaged with the outer peripheral portion of the chassis 101 .

[0029] Preferably, a track ring groove 501 is opened on the bottom side of the driving ring 5, and a guide ring 602 adapted to the shape of the track ring groove 501 is welded on the top of the driving ring 6, and the guide ring 602 is rotatably matched with the track ring groove 501.

[0030] Preferably, four vertical laser emitting heads 2 are embedded in the upper half of the outer shell of the measuring instrument body 1 in a cross-shaped symmetrical form, and the vertical laser emitting heads 2 are used to emit vertical measuring laser marking lines.

[0031] Preferably, two horizontal laser emitting heads 3 are symmetrically embedded in the lower half of the outer shell of the measuring instrument body 1, and the horizontal laser emitting heads 3 are used to emit horizontal measuring laser marking lines.

[0032] The following is a detailed explanation of the specific details, implementation steps, functions and interrelationships of the above features, as well as their role in implementing this technical solution: When in use, the measuring instrument is supported on the top plane of the foundation by three threaded lifting rods 103. The three threaded rod sleeves 104 are rotated forward and backward respectively to push and drive the three threaded lifting rods 103 to move up and down to level the measuring instrument.

[0033] The driving ring 5 is fixedly connected to the rotating ring 4 through three L-shaped connecting plates 401. Through the rotating ring 4, the driving ring 5 can rotate forward and backward along the outer periphery of the chassis 101, and the forward and reverse rotation operation of the driving ring 5 is implemented by holding it with the hand; the driving ring 6, the connecting rod 702, the L-shaped sliding member 701 and the arc-shaped rack 7 are connected together to form a crank slider mechanism. Through the crank slider mechanism, the forward driving ring 6 can push and drive the L-shaped sliding member 701 and the arc-shaped rack 7 to slide toward the driving gear 1041 at the corresponding position, and control the arc-shaped rack 7 to engage with the driving gear 1041. The forward driving operation of the driving ring 6 is implemented by pushing the finger plate 601 at the corresponding position by the finger holding the driving ring 5; the arc-shaped rack 7 is installed between the driving ring 5 and the rotating ring 4 through the L-shaped connecting plate 401. When the driving ring 5 is driven to rotate forward and reverse, the arc-shaped rack 7 can follow its synchronous movement.

[0034] When the arc-shaped rack 7 is meshed with the driving gear 1041 at the corresponding position and the driving ring 5 is driven to rotate forward, the arc-shaped rack 7 can mesh with and drive the threaded rod sleeve 104 at the corresponding position to rotate clockwise, and the threaded lifting rod 103 at the corresponding position is driven to rise and slide through the threaded rod sleeve 104; due to the limited length of the arc-shaped rack 7, the number of circles it drives the threaded rod sleeve 104 to rotate is also limited, and then the threaded lifting rod 103 is continuously driven to slide up and level the measuring instrument. It is necessary to reciprocate the driving ring 5 and the arc-shaped rack 7 to implement the threaded rod sleeve 104. Continuous, one-way, clockwise rotation drive is used to achieve continuous lifting adjustment of the threaded lifting rod 103. In order to prevent the arc-shaped rack 7 from driving the threaded rod sleeve 104 to rotate counterclockwise when rotating, causing the continuous lifting adjustment function of the threaded lifting rod 103 to fail, it is necessary to separate and decouple the arc-shaped rack 7 from the driving gear 1041 when rotating. When the arc-shaped rack 7 is driven to slide toward the driving gear 1041 and mesh with the driving gear 1041 for transmission, the spring on the L-shaped connecting plate 401 is compressed by the L-shaped sliding member 701, and then the finger can be released by simply releasing the finger plate. 601, the spring will lose the compressive holding force indirectly exerted on it by the drive ring 6, and automatically push back to drive the arc rack 7 to slide away from the drive gear 1041, controlling the arc rack 7 to separate and decouple from the drive gear 1041. In this way, when the corresponding part on the chassis 101 is continuously adjusted to rise, the drive ring 5 needs to be rotated back and forth, and in the process of the drive ring 5 being driven to rotate forward, the finger plate 601 is pushed by the finger to control the arc rack 7 to engage with the drive gear 1041 for transmission. In the process of the drive ring 5 being driven to rotate backward, the finger plate is released. 601 separates and decouples the arc-shaped rack 7 from the driving gear 1041. Similarly, when driving the threaded rod sleeve 104 to rotate continuously, unidirectionally, and counterclockwise to adjust the threaded lifting rod 103 to a continuous downward position, the driving ring 5 needs to be rotated back and forth. In the process of the driving ring 5 being driven to rotate forward, the finger is kept separated from the finger plate 601 to keep the arc-shaped rack 7 and the driving gear 1041 in a separated and decoupled state. In the process of the driving ring 5 being driven to rotate backward, the finger is used to push the finger plate 601 to control the arc-shaped rack 7 and the driving gear 1041 to engage and transmit.

[0035] The three threaded rod sleeves 104 and the three threaded lifting rods 103 together constitute three sets of threaded lifting structures for leveling the measuring instrument. The three sets of threaded lifting structures are arranged through the chassis 101 and are driven by the driving ring 5 arranged in the open space around the chassis 101. In this way, by directly twisting the driving ring 5 forward and backward in the open space around the chassis 101, the three sets of threaded lifting structures can be driven to rise and fall and slide respectively to complete the leveling of the entire measuring instrument. Compared with the existing technology in which the threaded lifting structure is completely set at the bottom of the chassis 101, this can save the trouble of having to reach into the cramped space between the chassis 101 and the plane to be measured in order to contact the threaded lifting structure to drive the threaded lifting structure for lifting and lowering when leveling the measuring instrument. This can avoid the cramped space from blocking and interfering with the operation of the hand driving the threaded lifting structure, and help to improve the convenience of the leveling operation of the measuring instrument.

[0036] The drive ring 5 and the arc-shaped rack 7 together constitute a lifting drive mechanism; by rotating the drive ring 5 forward and backward, the arc-shaped rack 7 can be adjusted to a position that meshes with the three drive gears 1041, and the three threaded lifting rods 103 are lifted and driven in turn to complete the leveling operation of the measuring instrument. This allows the three threaded lifting rods 103 to share a set of lifting drive mechanisms for lifting and driving, and can eliminate the need to configure a set of lifting drive mechanisms for each of the three threaded lifting rods 103, so that the lifting drive mechanism can be used for three purposes, which helps to simplify the structure for leveling the measuring instrument as a whole.

[0037] The lifting drive mechanism is a mechanism that drives the three sets of threaded lifting structures to perform common lifting and adjustment. The driving ring 5 is a component of the lifting drive mechanism. The driving ring 5 is a circular ring structure and is installed in the open space around the chassis 101. This arrangement allows the hand to hold the convenient holding part of the driving ring 5 and twist the driving ring 5 back and forth to implement it no matter what orientation the threaded lifting structure is in. Compared with the existing technology that lacks a mechanism that can drive the three sets of threaded lifting structures to perform common lifting and adjustment, this can eliminate the trouble of the staff turning their hands around the back of the measuring instrument and contacting the threaded lifting structure to drive the threaded lifting structure to lift when the threaded lifting structure on the back side of the measuring instrument is lifted and driven. The operation is simple and convenient.

[0038] The driving ring 6 is rotatably installed at the bottom of the driving ring 5 and is close to the driving ring 5. This allows the hand to hold the driving ring 5 to drive the driving ring 5 back and forth, and at the same time, use the finger to push or release the finger plate 601 to complete the meshing transmission and separation and decoupling operations of the arc-shaped rack 7 and the driving gear 1041. This allows the reciprocating drive operation of the driving ring 5 and the meshing transmission and separation and decoupling operations of the arc-shaped rack 7 and the driving gear 1041 to be performed with one hand without the need for significant movement of the hand, thereby saving the use of both hands and making the leveling operation of the measuring instrument simple and efficient.

[0039] The working principle of this embodiment: This measuring instrument needs to be used in conjunction with an external measuring ruler. When in use, place the measuring instrument on the top plane of the foundation to be measured, and then start the horizontal laser transmitter 3. After the horizontal laser transmitter 3 is started, it emits a horizontal measuring laser marking line. Then adjust the measuring ruler to an upright support state and place its bottom end against the top plane of the foundation. When the measuring ruler is in the above use state, the horizontal measuring laser marking line is projected on the measuring ruler. Then, move the measuring ruler on the top plane of the foundation several times along the length direction of the horizontal measuring laser marking line. During each movement, the measuring ruler will follow the ups and downs of the top plane of the foundation and observe the movement of each movement. After the operation, the projected position of the laser marking line on the measuring ruler is measured horizontally, and the scale value corresponding to the projected position on the measuring ruler is recorded. The recorded scale value is the height of the horizontally measured laser marking line from the top plane of the foundation. The change in this height can indirectly reflect the flatness of the top of the foundation. The difference between the two scale values recorded in each two adjacent moving operations is calculated in sequence. Finally, the average value of multiple differences is taken and compared with the standard error value (the standard error value is the height value that allows the top plane of the foundation to fluctuate). If the average value is less than the standard error value, the flatness of the top of the foundation is judged to be qualified, otherwise the flatness of the top of the foundation is judged to be unqualified.

[0040] In this article, there are several points to note: 1. The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention. Other structures may refer to conventional designs.

[0041] 2. In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to form new embodiments.

[0042] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A flatness laser measuring instrument for foundation engineering, including a measuring instrument main body (1), and a chassis (101) is fixedly connected to the bottom of the measuring instrument main body (1); It is characterized in that Three threaded lifting rods (103) that are rotationally limited are slidably installed around and through the outer edge part of the chassis (101). Three threaded rod sleeves (104) are rotationally installed around and through the outer edge part. The threaded lifting rods (103) are threadedly screwed and penetrated with the corresponding threaded rod sleeves (104). A driving gear (1041) is fixedly sleeved on the bottom end part of the threaded rod sleeve (104). A rotating ring (4) is rotationally sleeved on the outer circumference of the chassis (101). A plurality of L-shaped connecting plates (401) are welded around the outer circumference of the rotating ring (4). The tails of the plurality of L-shaped connecting plates (401) are welded with a driving ring (5). A driving circle (6) is rotationally installed at the bottom of the driving ring (5). A circle of finger-dial plates (601) are welded around the outer circumference of the driving circle (6). An arc-shaped rack (7) is slidably installed on one of the L-shaped connecting plates (401) in the form of spring pushing. In the idle state, the arc-shaped rack (7) is spaced apart from the driving gear (1041). In the use state, the arc-shaped rack (7) slides towards the driving gear (1041) and meshes with the driving gear (1041). A connecting rod (702) is rotationally connected between the arc-shaped rack (7) and the driving circle (6).

2. A flatness laser measuring instrument for foundation engineering according to claim 1, characterized in that: An L-shaped sliding member (701) is welded at the middle position on the outer side of the arc-shaped rack (7). The L-shaped sliding member (701) is jointly composed of an L-shaped sliding rod (7011) and a square sliding sleeve (7012) welded to the head end of the L-shaped sliding rod (7011); The tail end of the L-shaped sliding rod (7011) is fixedly welded to the arc-shaped rack (7). The square sliding sleeve (7012) is slidably matched with the horizontal plate section of the corresponding L-shaped connecting plate (401). The spring for pushing the arc-shaped rack (7) is sleeved on this horizontal plate section and is compressed and clamped between the rotating ring (4) and the square sliding sleeve (7012).

3. A flatness laser measuring instrument for foundation engineering according to claim 2, characterized in that: The head end of the connecting rod (702) is rotationally connected to the L-shaped sliding rod (7): and the tail end is rotationally connected to the inner circumference of the driving circle (6).

4. The flatness laser measuring instrument for foundation engineering according to claim 1, characterized in that: Three U-shaped limit members (102) are welded around the top end of the outer edge part of the chassis (10). The U-shaped limit member (102) is jointly composed of a limit ring (1022) and two L-shaped support rods (1021) symmetrically welded to the limit ring (1022). The threaded lifting rod (103) is slidably penetrated with the limit ring (1022). The tails of the two L-shaped support rods (1021) are fixedly welded to the chassis (101).

5. A flatness laser measuring instrument for foundation engineering according to claim 4, characterized in that: Two limit protrusions (1023) are integrally formed symmetrically on the inner circumference of the limit ring (1022). Two strip-shaped sliding grooves (1031) adapted to the shapes of the limit protrusions (1023) are symmetrically opened on the outer circumference of the threaded lifting rod (103). The two limit protrusions (1023) are slidably matched with the two strip-shaped sliding grooves (1031) correspondingly.

6. The flatness laser measuring instrument for foundation engineering according to claim 1, characterized in that: The rotating ring (4) has a U-shaped cross-sectional structure, and a circular track groove is opened thereon, and the circular track groove is rotationally matched with the outer peripheral part of the chassis (101).

7. The flatness laser measuring instrument for foundation engineering according to claim 1, characterized in that: A track ring groove (501) is formed on the bottom side of the driving ring (5), and a guide ring (602) adapted to the shape of the track ring groove (501) is welded to the top of the driving ring (6), and the guide ring (602) is rotatably engaged with the track ring groove (501).

8. The flatness laser measuring instrument for foundation engineering according to claim 1, characterized in that: Four vertical laser emitting heads (2) are embedded in the upper half of the outer shell of the measuring instrument body (1) in a cross-shaped symmetrical form. The vertical laser emitting heads (2) are used to emit vertical measuring laser marking lines.

9. The flatness laser measuring instrument for foundation engineering according to claim 1, characterized in that: Two horizontal laser emitting heads (3) are symmetrically embedded in the lower half of the outer shell of the measuring instrument body (1), and the horizontal laser emitting heads (3) are used to emit horizontal measuring laser marking lines.

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