A device for measuring the thickness of the pages of a case-bound book

Abstract

The utility model provides a kind of glue binding book page thickness measuring device, including fixed part and with the movable part between fixed part form for book page conveying path;It further includes the elastic member acting on movable part, it is configured as the book page that exceeds thickness passes through book page conveying path to make movable part displace, and it is driven movable part to reset using its elasticity.Adaptable detection on high-speed production line is realized with extremely simple mechanical layout.Fixed part and movable part form the book page conveying path of natural thickness sensing channel, while providing reset force, through its linear deformation characteristics, ensure the strict corresponding relationship of displacement and thickness value, fundamentally avoid measurement reference drift.

Description

Technical Field

[0001] This utility model relates to the field of perfect binding page measurement technology, specifically to a perfect binding page thickness measuring device. Background Technology

[0002] In the production of perfect-bound books, accurately detecting the thickness of individual pages or stacks of paper is crucial for ensuring bookbinding quality, especially in identifying abnormally thick pages caused by printing or folding errors or foreign objects. Real-time monitoring of page thickness is a key step in ensuring binding quality during perfect-bound book production. Traditional contact-type thickness measuring devices often use static pressing mechanisms in conjunction with sensors for direct measurement, but this has drawbacks: excessively thick books can easily cause the mechanism to jam or result in measurement distortion during continuous page transport, requiring frequent stops for resetting, leading to low measurement efficiency and making it difficult to meet the dynamic detection requirements of high-speed production lines. Summary of the Invention

[0003] This invention proposes a thickness measuring device for perfect bound books, which solves the problems of inaccurate dynamic measurement and low efficiency caused by reset delay and mechanism jamming in traditional thickness detection devices during high-speed continuous production of perfect bound books.

[0004] The technical solution of this utility model is implemented as follows:

[0005] A perfect binding page thickness measuring device includes a fixed member and a movable member forming a page transport path with respect to the fixed member; it also includes an elastic member acting on the movable member, which is configured to cause displacement of the movable member after a page exceeding the thickness passes through the page transport path, and uses its elasticity to drive the movable member to reset.

[0006] Furthermore, it also includes a linear guide rail, a sliding member a slidably disposed on the linear guide rail and fixedly connected to the bottom of the movable member, and a sliding member b slidably disposed on the linear guide rail; wherein, the two ends of the elastic member are connected to the adjacent sides of the sliding member b and the sliding member a.

[0007] Furthermore, it also includes a position locking mechanism; the position locking mechanism is configured to be connected to one side of the slider b to lock the slider b to establish a thickness detection reference, and to drive the slider a and the slider b to move synchronously to adjust the width of the page transport channel.

[0008] Furthermore, it also includes a frame assembly, which includes a first side mounting portion fixedly connected to the fastener on the side, a second side mounting portion fixedly connected to the position locking mechanism on the side, and a load-bearing portion fixedly connected to the linear guide rail on the top.

[0009] Furthermore, the fixing component includes a turntable a, which is connected to a connecting arm a via a bearing seat, and the side of the connecting arm a is connected to the first side mounting part of the frame assembly.

[0010] Furthermore, the movable component includes a turntable b, which is connected to a connecting arm b via a bearing seat. The bottom of the connecting arm b is fixedly connected to a base plate, and the base plate is connected to a sliding component b and a sliding component a.

[0011] Furthermore, the sliding member a includes a connecting plate a fixedly connected to the bottom plate at its top and a slide block a fixed at its bottom and slidably connected to the linear guide rail; the bottom of the connecting plate a is also provided with an extension member a, one side of which is fixedly connected to one end of the elastic member.

[0012] Furthermore, the sliding member b includes a connecting plate b that is slidably connected to the bottom plate at its top and a slide block b that is fixed at its bottom and slidably connected to the linear guide rail; the bottom of the connecting plate b is also provided with an extension member b, which is fixed to the other end of the elastic member.

[0013] Furthermore, the position locking mechanism includes a motor and a threaded transmission assembly connected to its output end and converting its rotational motion into linear displacement of the slider b.

[0014] Furthermore, the threaded transmission assembly includes a driving toothed pulley at the motor output end, the driving toothed pulley being connected to a driven toothed pulley via a toothed belt, and a lead screw being disposed through the driven toothed pulley. One side of the lead screw is threadedly connected to the extension member b, and the other side passes through the second side mounting part and is rotatably disposed therewith. The threaded transmission assembly is configured to drive the lead screw to rotate through the output action of the motor or to displace the sliding member b by manually rotating the end of the lead screw.

[0015] The beneficial effects of the technical solution provided in this application are as follows:

[0016] 1. This perfect binding page thickness measuring device significantly optimizes the efficiency of dynamic page thickness detection through the synergistic action of moving and elastic components. The moving component directly responds to instantaneous changes in page thickness by generating displacement, converting the thickness signal in real time through the physical motion of the mechanical structure itself, thus eliminating the complex sensing links of traditional static pressing mechanisms. Simultaneously, the elastic component immediately drives the moving component to reset after an extra-thick page passes through, without relying on an external power source or machine shutdown intervention, completely solving the measurement interruption problem caused by mechanism jamming in continuous production. This design integrates detection and reset functions into a single motion chain, significantly improving response speed and reliability.

[0017] 2. This perfect binding page thickness measuring device achieves adaptive detection on high-speed production lines with a minimalist mechanical layout. The page conveying path formed by the fixed and moving parts constitutes a natural thickness sensing channel. The elastic element provides a restoring force while ensuring a strict correspondence between the displacement and the thickness value through its linear deformation characteristics, fundamentally avoiding measurement reference drift. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the perfect binding page thickness measuring device of this utility model;

[0020] Figure 2 This is a front view schematic diagram of the perfect binding page thickness measuring device of this utility model;

[0021] Figure 3 This utility model Figure 1 Enlarged diagram of A in the middle;

[0022] Figure 4 This is an exploded schematic diagram of the perfect binding page thickness measuring device of this utility model;

[0023] Figure 5 This is a schematic diagram of the fastener of this utility model;

[0024] Figure 6 This is a schematic diagram of the movable part of this utility model;

[0025] Figure 7 This is a schematic diagram of the sliding component a of this utility model;

[0026] Figure 8 This is a schematic diagram of the sliding component b of this utility model;

[0027] Figure 9 This is a schematic diagram of the self-locking adjustment component of this utility model;

[0028] Figure 10 This is a schematic diagram of the frame components of this utility model.

[0029] In the diagram: 10 Fixture, 11 Turntable a, 12 Connecting arm a;

[0030] 20 Movable component, 21 Turntable b, 22 Connecting arm b, 23 Base plate;

[0031] 30 Sliding component a, 31 Connecting plate a, 32 Slide block a, 33 Extension component a;

[0032] 40 linear guide rails;

[0033] 50 Sliding component b, 51 Connecting plate b, 52 Slide block b, 53 Extension component b, 54 Channel plate, 55 Displacement sensor b;

[0034] 60 Position locking mechanism, 61 Motor, 62 Driving toothed pulley, 63 Toothed belt, 64 Driven toothed pulley, 66 Lead screw;

[0035] 70 Frame assembly, 71 First side mounting part, 72 Second side mounting part, 75 Bearing part, 74 Displacement sensor a;

[0036] 80 Page transport path, 90 Flexible elements. Detailed Implementation

[0037] The technical solution of this utility model will be clearly and completely described below with reference to its embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0038] Reference Figure 1-10 A perfect binding book page thickness measuring device includes a fixing member 10 and a movable member 20 forming a page transport path 80 with the fixing member 10. The fixing member 10 and the movable member 20 cooperate to construct the rigid reference side and dynamic response side of the page transport path 80: the fixing member 10 provides a stable thickness measurement reference surface, while the movable member 20, as a thickness-sensitive unit, directly maps the displacement of the page thickness. It also includes an elastic member 90 acting on the movable member 20, which gives the movable member 20 dual functional attributes—it absorbs the impact force of ultra-thick pages through elastic deformation to avoid mechanical jamming, and it drives the movable member 20 to precisely reset through energy storage and release, so that the initial width of the path 80 is automatically restored, ensuring the consistency of the reference for subsequent page thickness measurements. When the extra-thick page passes through path 80, the page squeezes the movable part 20, causing it to move outward. At this time, the elastic part 90 is compressed and stores energy. After the page has completely passed through, the elastic part 90 releases the stored elastic potential energy and pushes the movable part 20 back to its initial position. Thus, the closed-loop action of "thickness detection-automatic reset" is completed without external intervention, realizing the synchronous operation of dynamic detection of page thickness and self-maintenance of the mechanism.

[0039] In some embodiments, the system further includes a linear guide rail 40, a slider a30 slidably mounted on the linear guide rail 40 and fixedly connected to the bottom of the movable member 20, and a slider b50 slidably mounted on the linear guide rail 40; wherein, the elastic member 90 has its two ends connected to the adjacent sides of the slider b50 and the slider a30. The linear guide rail 40 provides a precise guide track for the displacement of the movable member 20, converting the radial displacement of the movable member 20 caused by the page thickness into linear sliding; the slider a30 serves as a rigid transmission carrier for the movable member 20, directly transmitting its displacement to the guide rail plane; the slider b50, through the elastic member 90 and the slider a30, forms an elastic linkage system, becoming a mechanical reference point for thickness detection in the locked state, ensuring that the deformation of the elastic member 90 strictly corresponds to the change in page thickness. The elastic member 90 includes, but is not limited to, springs and disc springs.

[0040] When the movable part 20 is squeezed outward by the extra-thick book page, it drives the fixed sliding part a30 to slide along the linear guide rail 40, simultaneously compressing the elastic part 90 connected between the sliding part a30 and the sliding part b50. After the book page passes, the elastic part 90 pushes the sliding part a30 to slide in the opposite direction along the guide rail, pulling the movable part 20 to accurately reset, while the preset position of the sliding part b50 remains fixed, ensuring that the direction and magnitude of the elastic reset force are constant.

[0041] In some embodiments, a position locking mechanism 60 is also included. The position locking mechanism 60 is the core of dynamic control of the thickness detection reference: First, by rigidly locking the position of the slider b50, a fixed mechanical fulcrum for the deformation of the elastic element 90 is established, ensuring the absolute stability of the thickness measurement reference. Second, when adjusting the width of the page conveying path 80, the slider a30 and slider b50 are driven to move synchronously along the linear guide rail 40, so that the pre-compression of the elastic element 90 changes adaptively, thereby maintaining the thickness detection sensitivity unchanged while changing the channel width. When the detection reference needs to be locked, the position locking mechanism 60 rigidly fixes the slider b50 on the guide rail 40. At this time, the displacement of the slider a30 driven by the ultra-thick page squeezing movable part 20 will be directly converted into the linear deformation of the elastic element 90. When the width of the path 80 needs to be adjusted, the position locking mechanism 60 releases the fixation of the slider b50, drives the slider b50 and slider a30 to slide synchronously as a whole, and the elastic element 90 maintains a constant deformation as the two move at equal distances, realizing the coordinated reconstruction of channel width adjustment and detection reference.

[0042] In some embodiments, a frame assembly 70 is also included, comprising a first side mounting portion 71, a second side mounting portion 72, and a support portion 75. The frame assembly 70 acts as the rigid nerve center of the device. Its first side mounting portion 71 anchors the fixing member 10 as an immovable thickness measurement reference, the second side mounting portion 72 absorbs the adjustment force and self-locking reaction force of the position locking mechanism 60 within the overall frame, and the support portion 75 provides undisturbed floating support for the linear guide rail 40. The three components work together to construct an absolute coordinate system in the spatial dimension, so that the micro-displacement caused by the page squeezing movable part 20 and the macro-width adjustment driven by the position locking mechanism 60 are both accurately transmitted under a unified rigid reference.

[0043] In some embodiments, the fixing member 10 includes a turntable a11, which is connected to a connecting arm a12 via a bearing seat. The side of the connecting arm a12 is connected to the first side mounting portion 71 of the frame assembly 70. The turntable a11 serves as a flexible guide portal for the page entry path 80, guiding the page smoothly through the rotational freedom of the bearing seat, transforming the risk of corner jamming caused by traditional rigid baffles into rolling contact. The connecting arm a12 acts as a bridge between rigidity and flexibility, absorbing the slight sway of the turntable a11 at one end, and rigidly anchoring the other end to the first side mounting portion 71 of the frame assembly 70, thus transmitting the page thrust to the overall frame structure without damage. This eliminates local stress concentration and ensures that the spatial coordinates of the fixing member 10, as a measurement reference, remain absolutely constant.

[0044] In some embodiments, the movable component 20 includes a turntable b21, which is connected to a connecting arm b22 via a bearing seat. The bottom of the connecting arm b22 is fixedly connected to a base plate 23, which is connected to a sliding component b50 and a sliding component a30. The turntable b21 acts as a dynamic pressure gateway for the pages leaving the path 80. Through the rotational freedom of the bearing seat, it transforms the squeezing impact of the ultra-thick pages into smooth rolling contact. Simultaneously, through the leverage effect of the connecting arm b22, it accurately transmits the radial pressure to the bottom. The base plate 23 acts as a displacement distribution center, transforming the arc-shaped swing of the connecting arm b22 into linear displacement. Through its rigid connection with the sliding component a30 and its sliding engagement with the sliding component b50, it achieves the dual mission of efficiently transmitting the squeezing displacement of the movable component 20 to the deformation of the elastic component 90 and guiding the path reset. When the extra-thick pages press against the turntable b21, the rotation of the turntable b21 eliminates the tangential frictional resistance on the page surface, allowing the pages to pass smoothly through path 80. At this moment, the radial thrust of the pages on the turntable b21 is rigidly transmitted through the connecting arm b22, driving the base plate 23 to translate outward. The base plate 23 pushes the fixed sliding member a30 to slide linearly along the guide rail, compressing the elastic member 90. At the same time, the sliding connection between the elastic member a30 and the sliding member b50 releases the small angular deviation caused by the assembly tolerance, ensuring that the deformation direction of the elastic member 90 is strictly parallel to the page conveying axis.

[0045] In some embodiments, the sliding member a30 includes a connecting plate a31 fixedly connected to the bottom plate 23 at its top and a slide block a32 fixed at its bottom and slidably connected to the linear guide rail 40; the bottom of the connecting plate a31 is also provided with an extension a33, one side of which is fixedly connected to one end of the elastic member 90. The connecting plate a31 serves as a rigid displacement conversion bridge between the movable member 20 and the linear guide rail 40. Its fixed connection with the bottom plate 23 converts the movement of the movable member 20 into a purely linear movement, while the bottom slide block a32 acts like a sliding shoe on a precision track, introducing the page thrust into the directional sliding plane of the linear guide rail 40 without loss; the extension a33 extends cantilevered from the bottom of the connecting plate a31, becoming a dedicated mechanical interface for the elastic member 90. Through its fixed connection with the elastic member 90 on one side, it accurately converts the linear displacement of the sliding member a30 into the axial compression deformation of the elastic member 90, forming the first link of the mechanical signal chain for thickness detection.

[0046] In some embodiments, the sliding member b50 includes a connecting plate b51 slidably connected to the bottom plate 23 at its top and a slide block b52 fixed at its bottom and slidably connected to the linear guide rail 40; the bottom of the connecting plate b51 52 is also provided with an extension b53, which is fixed to the other end of the elastic member 90. The sliding connection between the connecting plate b51 and the bottom plate 23 constitutes the displacement decoupling hub of the movable member 20, allowing the bottom plate 23 to freely push the sliding member a30 while maintaining its own position lock during thickness detection, thus avoiding interference with the deformation measurement of the elastic member 90; the slide block b52 acts as a reference anchor point on the guide rail 40, uniformly distributing the rigid fixing force of the position locking mechanism 60 to the guide rail plane through the linear sliding pair; the extension b53 extends out from the bottom of the connecting plate b51, becoming the fixed mechanical end of the elastic member 90, and through its fixed connection with the other end of the elastic member 90, the sliding member b50 becomes the origin of the absolute reference coordinate system for thickness detection in the locked state.

[0047] In some embodiments, the position locking mechanism 60 includes a motor 61 and a threaded transmission assembly connected to its output end and converting its rotational motion into linear displacement of the sliding member b50. The threaded transmission assembly includes a driving toothed wheel 62 at the output end of the motor 61, the driving toothed wheel 62 being driven by a driven toothed wheel 64 via a toothed belt 63, and a lead screw 66 passing through the driven toothed wheel 64. One side of the lead screw 66 is threaded to the extension member b53, and the other side passes through the second side mounting portion 72 and is rotatably disposed therewith. The threaded transmission assembly is configured to drive the lead screw 66 to rotate through the output action of the motor 61 or to displace the sliding member b50 by manually rotating the end of the lead screw 66. The collaborative architecture of the motor 61 and the threaded transmission assembly constitutes the intelligent drive core of the position locking mechanism 60: the active toothed wheel 62 converts the high-speed rotation of the motor 61 into the directional transmission force of the toothed belt 63, while the driven toothed wheel 64, like a precision torque converter, converts the belt tension into the low-speed, high-torque rotation of the lead screw 66; the rotational design of the lead screw 66 through the second side mounting part 72 makes it a suspended thrust shaft, and one end of it, through the threaded engagement extension b53, refines the rotational motion into the micron-level linear displacement of the sliding part b50. At the same time, relying on the inclined self-locking effect of the lead screw thread, the position of the sliding part b50 is naturally frozen in the non-drive state, realizing the zero-energy absolute locking of the mechanical reference.

[0048] When the motor 61 starts, the driving toothed wheel 62 pulls the toothed belt 63 to drive the driven toothed wheel 64 to rotate, forcing the lead screw 66 to rotate synchronously under the bearing constraint of the second mounting part 72. At this moment, the threaded inclined surface of the lead screw 66 and the internal thread of the extension b53 generate a helical thrust, pushing the slider b50 to slide precisely along the linear guide rail 40. If manual fine adjustment is required, external force can be used to rotate the exposed end of the lead screw 66 to trigger the helical thrust mechanism. Once the drive stops, the threaded pair of the lead screw 66 and the extension b53 immediately solidifies their relative positions due to the self-locking of the friction angle, making the slider b50 immovable as if welded to the guide rail.

[0049] The frame assembly 70 also includes a detection mounting section 73 disposed between the first side mounting section 71 and the second side mounting section 72. The detection mounting section 73 is equipped with a displacement sensor a74 for detecting the displacement of the sliding member a30. The detection mounting section 73, acting as a neutral monitoring platform for the frame assembly 70, is suspended in the mechanically neutral zone between the first side mounting section 71 and the second side mounting section 72. The displacement sensor a74 it carries acts like an observation tower erected on vibration-free bedrock, continuously capturing the linear displacement trajectory of the sliding member a30 with the absolute coordinate system of the frame as a reference. It converts the page thickness value mapped by the deformation of the elastic member 90 into an electrical signal, while avoiding the drift of the detection reference caused by the deformation of the frame under stress, providing a zero-interference signal source for thickness detection.

[0050] A grooved plate 54 is fixed to the top or side of the sliding plate b51. The front and rear sides of the base plate 23 have guide openings 24 that are adapted to and slidably connected to the grooved plate 51, so as to ensure that when the movable part 20 slides relative to the sliding part b50, the base plate 23 at its bottom will not drive the sliding part 50 to slide synchronously. When the extra-thick page pushes the movable part 20 to move the base plate 23 outward, the guide opening 24 of the base plate 23 slides smoothly along the U-shaped groove of the grooved plate 54. At this time, the grooved plate 54 is like a stationary coordinate axis welded to the sliding part b50, providing only the geometric constraint of the sliding pair without transmitting any driving force, so that the sliding part b50, which is fixed by the position locking mechanism 60, is as immovable as a foundation pile driven into concrete. The base plate 23 automatically corrects the assembly misalignment angle through the gap fit between the guide opening 24 and the grooved plate 54, eliminating the displacement jamming caused by the machining tolerance, and ensuring that the displacement freedom and reference stability of the movable part 20 are mechanically unified in the contradiction during thickness detection.

[0051] The sliding member b50 also includes a displacement sensor b55 located on the front side of the connecting plate b51. The detection area of ​​the displacement sensor b55 falls on one side of the guide opening 24. By detecting the position change of the side, the displacement of the moving member 20 can be known. When the ultra-thick page driving base plate 23 slides along the channel plate 54 with the guide opening 24, the laser or electromagnetic wave detection beam of the displacement sensor b55 continuously scans the displacement trajectory of the edge of the guide opening 24. At this time, the sliding member b50, which is fixed by the position locking mechanism 60, becomes an absolutely stationary coordinate system. The displacement sensor b55 is like an observation station welded to the origin of the coordinate system. The change in the distance between its detection area and the edge of the guide opening 24 directly maps the displacement amplitude of the moving member 20. The U-shaped structure of the channel plate 54 opens an unobstructed optical channel for the detection beam, so that the thickness detection signal can be acquired with high fidelity in an environment with zero mechanical interference.

[0052] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for measuring the thickness of perfect bound book pages, characterized in that, It includes a fixing member (10) and a movable member (20) forming a page transport path (80) with the fixing member (10); it also includes an elastic member (90) acting on the movable member (20), which is configured to cause the movable member (20) to be displaced after a page exceeding the thickness passes through the page transport path (80), and to drive the movable member (20) to reset by utilizing its elasticity.

2. The perfect binding page thickness measuring device as described in claim 1, characterized in that, It also includes a linear guide rail (40), a sliding member a (30) slidably disposed on the linear guide rail (40) and fixedly connected to the bottom of the movable member (20), and a sliding member b (50) slidably disposed on the linear guide rail (40); wherein, the two ends of the elastic member (90) are connected to the adjacent sides of the sliding member b (50) and the sliding member a (30).

3. The perfect binding page thickness measuring device as described in claim 2, characterized in that, It also includes a position locking mechanism (60); the position locking mechanism (60) is configured to be connected to one side of the slider b (50) to lock the slider b (50) to establish a thickness detection reference, and to drive the slider a (30) and the slider b (50) to move synchronously to adjust the width of the page transport channel.

4. The perfect binding page thickness measuring device as described in claim 3, characterized in that, It also includes a frame assembly (70), which includes a first side mounting part (71) fixedly connected to the fastener (10) on the side, a second side mounting part (72) fixedly connected to the position locking mechanism (60) on the side, and a support part (75) fixedly connected to the linear guide rail (40) on the top.

5. The perfect binding page thickness measuring device as described in claim 4, characterized in that, The fastener (10) includes a turntable a (11), which is connected to a connecting arm a (12) via a bearing seat. The side of the connecting arm a (12) is connected to the first side mounting part (71) of the frame assembly (70).

6. The perfect binding page thickness measuring device as described in claim 4, characterized in that, The movable component (20) includes a turntable b (21), which is connected to a connecting arm b (22) via a bearing seat. The bottom of the connecting arm b (22) is fixedly connected to a base plate (23), and the base plate (23) is connected to a sliding component b (50) and a sliding component a (30).

7. The perfect binding page thickness measuring device as described in claim 6, characterized in that, The sliding member a (30) includes a connecting plate a (31) whose top is fixedly connected to the bottom plate (23) and a slide block a (32) whose bottom is fixed and slidably connected to the linear guide rail (40); the bottom of the connecting plate a (31) is also provided with an extension a (33), one side of the extension a (33) being fixedly connected to one end of the elastic member (90).

8. The perfect binding page thickness measuring device as described in claim 6, characterized in that, The sliding member b (50) includes a connecting plate b (51) that is slidably connected to the top of the base plate (23) and a slide block b (52) that is fixed at its bottom and slidably connected to the linear guide rail (40); the bottom of the connecting plate b (51) is also provided with an extension b (53), which is fixed to the other end of the elastic member (90).

9. The perfect binding page thickness measuring device as described in claim 8, characterized in that, The position locking mechanism (60) includes a motor (61) and a threaded drive assembly connected to its output and converting its rotational motion into linear displacement of the slider b (50).

10. The perfect binding page thickness measuring device as described in claim 9, characterized in that, The threaded drive assembly includes a drive gear (62) at the output end of a motor (61), and a driven gear (64) is driven to the drive gear (62) via a toothed belt (63). A lead screw (66) is provided through the driven gear (64). One side of the lead screw (66) is threaded to the extension b (53), and the other side passes through the second side mounting part (72) and is rotatably disposed therewith. The threaded drive assembly is configured to drive the lead screw (66) to rotate by the output action of the motor (61) or to allow the sliding member b (50) to be displaced by manually rotating the end of the lead screw (66).

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