Patent Publication Number: US-2023158655-A1

Title: Fastening device

Description:
RELATED APPLICATIONS 
     The present application is a continuation-in-part (CIP) application of International Application No. PCT/CN2020/104451 filed on Jul. 24, 2020, the disclosure of which is incorporated herein in its entirety by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a power tool, and in particular to a fastening device with an adjustable handle. 
     DESCRIPTION OF THE PRIOR ART 
     The installation of wooden boards is one of the most common procedures in construction and decoration processes. Among other things, the installation of floorings is the most common. A common flooring installation method is to lay keels on the ground, lay flooring materials having a standard size and a tongue-groove structure reasonably, and fix floorings to the keels with nails. Specifically, the nails are driven diagonally into tongue parts of the floorings to connect same to the keels. This process is repeated for each flooring until all the floorings are secured. 
     In a construction process, a flooring nail gun is a commonly used tool. The flooring nail gun has the advantages of high accuracy, labor saving, high efficiency, and not easy to damage materials. This enables the installation of the wooden boards to operate efficiently. 
     However, the flooring nail gun also has its limitations. Since the nails for fixing the floorings need to be driven in one time, there are certain requirements for the strength and weight of the nail gun itself. If its own strength or weight cannot meet the requirements, it will cause problems such as failure to drive the nail, rebound, and damage. Therefore, a main body of the commonly used nail gun is mainly made of cast iron, which has a certain weight and is cumbersome to move. Especially during use, a user needs to stand up or squat down according to the actual situation, and the nail gun needs to be moved frequently. If the holding posture is not appropriate, it will cause fatigue of hands, arms, and the back, so that it is impossible for the user to work for a long time, thus reducing the work efficiency, and even causing a physical injury. 
     In the prior art, some techniques have appeared to improve the posture of the user holding the flooring nail gun. 
     For example, in some technical solutions, a handle that can be raised and lowered is used. When the user is standing up for construction, the handle can be raised to prevent the user from bending; and when the user is squatting down, the handle can be lowered to avoid being unable to hold it properly. 
     In some application scenarios, due to the height limitation of the site, the nail gun cannot fully enter the construction space. Therefore, in some technical solutions, the handle is additionally provided with a rotating shaft, such that the handle can be turned away from the plane where a base is located, and the absolute height of the nail gun is reduced during the construction process. 
     Although the above prior art can improve the posture of the user holding the nail gun to a certain extent, there are still some unsolved technical problems. For example, in the prior art, although the height of the handle can be changed in some ways, the angle at which the handle is held cannot be changed. The user needs to hold the nail gun at the same angle in different postures, which will still cause inconvenience and fatigue. In addition, the nail gun needs to be moved frequently. The larger the construction area, the greater the frequency and range of movement. For a bulky main body, an auxiliary moving device is necessary. If the addition of an auxiliary moving device is considered only, the volume and weight of the main body will further increase, which will have an unfavorable effect on transportation and packaging. 
     Therefore, those skilled in the art devote themselves to developing a fastening device to solve the technical problems existing in the prior art. Such a fastening device can be used for the installation of floorings. Not only can the height of a handle be changed, but also the angle at which the handle is held can be changed at the same time. Moreover, the fastening device is further provided with a detachable auxiliary moving device, which can easily move a base during use, but the auxiliary moving device can be removed when it is not needed, which is convenient for packaging and transportation. 
     SUMMARY OF THE INVENTION 
     In view of the above defects in the prior art, the technical problem to be solved by the present invention is how to provide a fastening device, which can reduce the fatigue of users, improve the work efficiency and facilitate movement and transportation. 
     In order to achieve the above object, the present invention provides a fastening device comprising a main body and a holding part, wherein the holding part is connected to the main body. 
     Further, the holding part comprises a first arm, the first arm is provided with a first connection mechanism, and the first arm is rotatably connected to the main body via the first connection mechanism. 
     Further, the first connection mechanism comprises a first shaft, the first arm is configured to be able to rotate about the first shaft, and the first connection mechanism is provided with a first locking/unlocking mechanism, such that the first arm has at least two locking positions where the first arm is able to be stationary relative to the main body when no external force is applied. 
     Further, the holding part also comprises a second arm, the first arm is further provided with a second connection mechanism, the second arm is rotatably connected to the first arm via the second connection mechanism, and the second connection mechanism is provided with a second locking/unlocking mechanism, such that the second arm has at least two locking positions where the second arm is able to be stationary relative to the main body when no external force is applied. 
     Further, the second connection mechanism comprises: a lug provided on the second arm, the lug being provided with a first through-hole; and a second through-hole provided in the first arm, wherein the first through-hole and the second through-hole are overlapped to allow a strip-shaped object to pass through, so as to connect the first arm and the second arm. 
     Further, the second locking/unlocking mechanism further comprises a pin, a retaining shaft and an operation part, wherein the retaining shaft is fixedly connected to the operation part via the pin; the pin and the retaining shaft both pass through the first through-hole and the second through-hole; the pin, the retaining shaft, and the operation part are coaxially arranged with the second shaft; and the operation part is configured to be able to drive the retaining shaft to move axially under the action of an external force. 
     Further, a toothed ring is fixedly provided on an inner side of the first through-hole, rotating shaft teeth are fixedly provided on an outer surface of the retaining shaft, and the retaining shaft is configured to be able to realize the engagement and disengagement between the rotating shaft teeth and the toothed ring under the drive of the operation part. 
     Further, a toothed ring is provided on an inner side of the first through-hole, rotating shaft teeth are fixedly provided on an outer surface of the retaining shaft, and the toothed ring engages with the rotating shaft teeth and is configured to be able to realize the locking and unlocking between the toothed ring and the lug under the control of the operation part. 
     Further, a toothed ring is fixedly provided on an inner side of the first through-hole, a rotating shaft teeth is provided in the second through-hole, and the toothed ring engages with the rotating shaft teeth and is configured to be able to realize the locking and unlocking between the rotating shaft teeth and the first arm under the control of the operation part. 
     Further, an inner side of the first through-hole is provided with a retaining groove, an outer side of the retaining shaft is provided with two one-way bearings, and the size and the shape of an inner contour of the retaining groove conform to those of an outer contour of each of the two one-way bearings; the rotation directions of the two one-way bearings are opposite; and the retaining shaft is configured to be able to realize the locking and separation between the two one-way bearings and the retaining groove under the drive of the operation part. 
     Further, the holding part also comprises a third arm connected to the main body. 
     Further, a base is also comprised, which comprises an adjustable plate and a height adjustment part, wherein the height of the adjustable plate is changed by the height adjustment part. 
     Further, the height adjustment part comprises a stud fixedly connected to the adjustable plate, and the adjustable plate is connected to the main body via the stud. 
     Further, the main body is provided with an annular rotating disk, and threads on an inner surface of the annular rotating disk engage with threads on an outer surface of the stud. 
     Further, the height adjustment part comprises an adjustment camshaft, and an upper surface of the adjustable plate is in contact with the camshaft. 
     Further, the height adjustment part comprises two camshafts, the main body is provided with a driving wheel, and each of the camshafts is provided with a driven wheel, the driven wheels are connected to the driving wheel, and the driven wheels are configured to drive the two camshafts to rotate at the same angular velocity. 
     Further, a base is also comprised, which comprises a base body and a moving mechanism detachably connected to the base body. 
     Further, the moving mechanism comprises roller brackets detachably connected to the base body. 
     Further, sliding grooves are provided on sides of the base body, and the roller brackets are connected to the base body via the sliding grooves. 
     Further, each of the roller brackets is provided with a bracket ball, a ball retaining groove is provided at a corresponding position on the respective sliding groove, and the bracket ball mates with the ball retaining groove to realize the locking of the roller bracket. 
     Compared with the prior art, the present invention has at least the following technical effects:
         1) With the adjustment of two connection mechanisms of the present invention, the overall height of the device can be adjusted to adapt to the heights of different users, or adapt to the construction postures of standing up or squatting down, so as to reduce the fatigue of the user due to the improper height or standing posture, and this is also convenient for packaging and transportation.   2) In the present invention, the angle of the second arm can be adjusted to adapt to the hand-held angle of the user, and reduce the fatigue of the user due to the improper holding posture.   3) In an embodiment of the present invention, the holding part can be rotated to different planes, and the present invention is therefore suitable for scenarios where the construction space is limited.   4) In an embodiment of the present invention, an adjustable backing plate is designed to reduce the damage to a wooden board in the present invention.   5) In an embodiment of the present invention, an auxiliary moving mechanism is designed to facilitate the movement of the entire device and reduce the fatigue of the user due to frequent and long-distance movement.   6) In the present invention, since the device can be folded, the overall volume during transportation is small, and the cost of packaging and transportation can be reduced; and the device can be applied to various working scenarios and reduce the fatigue of the user, so that the work efficiency is improved and the average construction cost is reduced.   7) The concept, specific structure and resulting technical effects of the present invention are further described below in conjunction with the drawings to fully understand the object, features, and effects of the present invention.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of an overall structure in a state according to an embodiment of the present invention; 
         FIG.  2    is a schematic diagram of the rotation of a second handle according to an embodiment of the present invention; 
         FIG.  3    is a schematic diagram of an overall structure in another state according to an embodiment of the present invention; 
         FIG.  4    is a schematic exploded structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  5    is a schematic structural diagram of a second connection mechanism with a button being released according to an embodiment of the present invention; 
         FIG.  6    is a schematic structural diagram of a second connection mechanism with a button being pressed according to an embodiment of the present invention; 
         FIG.  7    is a schematic exploded structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  8    is a schematic structural diagram of a one-way bearing used in an embodiment of the present invention; 
         FIG.  9    is a schematic structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  10    is a schematic exploded structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  11    is a schematic structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  12    is a schematic structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  13    is a schematic structural diagram of a knob used in an embodiment of the present invention; 
         FIG.  14    is a schematic structural diagram of a holding part according to an embodiment of the present invention; 
         FIG.  15    is a schematic structural diagram of a holding part according to an embodiment of the present invention; 
         FIG.  16    is a schematic structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  17    is a schematic structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  18    is a schematic structural diagram of a second connection mechanism according to an embodiment of the present invention; 
         FIG.  19    is a schematic diagram of an overall structure in a state according to an embodiment of the present invention; 
         FIG.  20    is a schematic diagram of an overall structure in another state according to an embodiment of the present invention; 
         FIG.  21    is a schematic structural diagram of a base and a moving mechanism according to an embodiment of the present invention; 
         FIG.  22    is a schematic exploded structural diagram of a base and a moving mechanism according to an embodiment of the present invention; 
         FIG.  23    is a position marking diagram of cross-sections of a base and a moving mechanism according to an embodiment of the present invention; 
         FIG.  24    is a cross-sectional diagram of a base and a moving mechanism according to an embodiment of the present invention; 
         FIG.  25    is a cross-sectional diagram of a base and a moving mechanism according to an embodiment of the present invention; 
         FIG.  26    is a cross-sectional diagram of a base and a moving mechanism according to an embodiment of the present invention; 
         FIG.  27    is a cross-sectional diagram of an adjustable plate according to an embodiment of the present invention; 
         FIG.  28    is a schematic structural diagram of an adjustable plate according to an embodiment of the present invention; and 
         FIG.  29    is a schematic structural diagram of an adjustable plate according to an embodiment of the present invention. 
     
    
    
     In the figures,  1 —base,  11 —base body,  111 —limiting plate,  112 —rotating disk,  113 —circlip,  114 —rotating disk bolt,  12 —adjustable plate,  121 —adjustable plate stud,  122 —backing plate,  123 —backing plate screw,  124 —height adjustment part,  1241 —driving wheel,  1242 —connecting rod,  1243 —driven wheel,  1244 —driving gear,  1245 —driven gear,  125 —height adjustment camshaft,  13 —roller bracket,  14 —roller,  15 —sliding groove,  16 —bracket ball,  17 —bracket ball retaining groove,  2 —fastener container,  3 —driving mechanism,  4 —holding part,  41 —first connection mechanism,  42 —first handle,  421 —groove,  43 —second connection mechanism,  431 —button,  432 —spring,  433 —pin,  434 —retaining shaft,  435 —rotating shaft tooth,  436 —bearing matching part,  437 —one-way bearing,  438 —knob,  4381 —ball groove,  439 —ball,  4310 —ball spring,  4311 —eccentric cam,  4312 —lever,  4313 —raised shaft,  4314 —toothed fastener,  44 —second handle,  441 —toothed ring,  442 —lug,  443 —retaining groove,  5 —third handle. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention are described below with reference to the drawings of the description to make the technical contents clearer and easier to understand. The present invention can be embodied in various forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein. 
     In the drawings, the same reference numeral indicates components having the same structure, and similar reference numerals indicate assemblies having similar structures or functions throughout. The size and thickness of each assembly shown in the figures are shown arbitrarily, and the present invention does not define the size and thickness of each assembly. In order to make the illustration clearer, the thickness of the component in some places of the figures is appropriately exaggerated. 
     Embodiment 1 
       FIGS.  1  to  3    show diagrams of an overall structure according to an embodiment of the present invention. In this embodiment, a base  1 , a fastener container  2 , a driving mechanism  3  and a holding part  4  are comprised. When this embodiment is applied to the installation of floorings, the fastener container  2  is a magazine for accommodating flooring nails, and the driving mechanism  3  may be of a gas driven or electrically driven type. The fastener container  2  is detachably and fixedly connected to the base  1 , and the preferred connection method includes snap-fitting and the like. The driving mechanism  3  is fixedly connected to the base  1 . The holding part  4  comprises a first handle  42  and a second handle  44 . The first handle  42  and the driving mechanism  3  are connected via the first connection mechanism  41 . In other embodiments, the first handle  42  may also be directly connected to the base  1 . The second handle  44  and the first handle  42  are connected via a second connection mechanism  43 . In this embodiment, the fastener container  2  and the driving mechanism  3  are both strip-shaped, and a line a where the fastener container  2  is located and a line b where the driving mechanism  3  is located intersect, forming a main plane. The plane where a lower surface of the base  1  is in contact with a wooden board is an operation plane. The main plane is arranged to be perpendicular to the operation plane. 
     The preferred connection method of the first connection mechanism  41  and the second connection mechanism  43  is hinged connection, that is, a first shaft is provided at the first connection mechanism  41  and a second shaft is provided at the second connection mechanism  43 , such that the first handle  42  rotates about the first shaft relative to the driving mechanism  3 , and the second handle  44  rotates about the second shaft relative to the first handle  42 . In this embodiment and other embodiments below, the arrangements of the second connection mechanism  43  and the second shaft will be described specifically. The first connection mechanism  41  and the first shaft may adopt any of the arrangements described below to achieve the same technical effect. 
     Different settings of the direction of the second shaft can make the rotation position of the second handle  44  different. If the second shaft is arranged to be perpendicular to the main plane, the second handle  44  rotates about the second shaft in the main plane. If the second shaft is arranged to be parallel to the main plane, most particularly, the second shaft is in the main plane and is arranged to be parallel to the main plane, when the second handle  44  rotates about the second shaft, it may be in the main plane or may form a certain included angle with the main plane. No matter which direction the second shaft is arranged in, the second connection mechanism  43  provides at least two locking positions, such that the second handle  44  is fixed relative to the first handle  42 . At the same time, an operation part is provided, and the second handle  44  can be locked and unlocked by the operation part. 
     As shown in  FIGS.  1  and  3   , through the adjustment of the first connection mechanism  41  and the second connection mechanism  43 , different postures of the first handle  42  and the second handle  44  can cause the overall height of the device to be changed from H 1  in  FIGS.  1    to H 2  in  FIG.  3   , wherein H 1  is different from H 2 . For the convenience of description, it is assumed that H 1  is greater than H 2 . When the height of the user is relatively high, or in the case of standing up, the setting with higher overall height can be selected, that is, the state in  FIG.  1   , and when the height of the user is relatively short, or in the case of squatting down for construction, the setting with lower overall height can be used, that is, the state in  FIG.  3   , so as to reduce the fatigue of the user due to the improper height or standing posture. In addition, the reduction in the overall height also facilitates packaging and transportation. 
     Due to the existence of the second connection mechanism  43 , the second handle  44  can be adjusted to various angles. When the device is in different positions relative to the user, the angle of the second handle  44  can be adjusted to meet different holding postures of the user, so as to reduce the fatigue of the user caused by improper holding postures and to increase the work efficiency. 
     Embodiment 2 
       FIGS.  4  to  6    show specific structures of a second connection mechanism  43  in an embodiment of the present application. A groove  421  provided on the first handle  42  and a lug  442  provided on the second handle  44  are comprised. The size of the groove  421  matches that of the lug  442 , and through-holes are provided at corresponding positions of the groove  421  and the lug  442 . The through-holes may allow a strip-shaped object to pass through, thereby connecting the first handle  42  and the second handle  44 . It should be noted that in  FIGS.  4  to  6   , since the groove  421  is a U-shaped groove with two walls, it is necessary to provide three through-holes. In other embodiments, a single-wall groove may also be used. It is only necessary to provide a corresponding number of through-holes to ensure the connection between the first handle  42  and the second handle  44 . In addition, in this embodiment, the three through-holes are coaxially arranged. In other embodiments, the through-holes may not be strictly coaxially arranged, and it is only necessary to ensure that the passage of the strip-shaped object can realize the rotatable connection of the first handle  42  and the second handle  44 . In this embodiment, teeth are further provided on the inner side of the through-hole provided in the lug  442 , such that the through-hole becomes a toothed ring  441 . In order to provide a retaining function, a button  431 , a spring  432 , a pin  433  and a retaining shaft  434  are provided in this embodiment. The retaining shaft  434  is fixedly connected to the button  431  via the pin  433 . The pin  433  is coaxially arranged with the retaining shaft  434  to form a second shaft. The retaining shaft  434  is cylindrical, and a portion thereof away from the button  431  is provided with rotating shaft teeth  435 . When the retaining shaft  434  is at a proper position, the rotating shaft teeth  435  engages with the toothed ring  441  to form the locking of the first handle  42  and the second handle  44 . When the retaining shaft  434  is at another proper position, the rotating shaft  435  is separated from the toothed ring  441  to realize unlocking. 
       FIG.  5    shows a locked state of this embodiment. The spring  432  is provided between the button  431  and the toothed ring  441 , such that an elastic force of the spring  432  drives the button  431  to move away from the toothed ring  441  and at the same time drives the retaining shaft  434  to move axially along the second shaft. Accordingly, the rotating shaft teeth  435  is at the position where they engage with the toothed ring  441 . 
       FIG.  6    shows an unlocked state of this embodiment. An external force is applied to the button  431 , such that the button  431  is close to the toothed ring  441 , and at the same time, the retaining shaft  433  is driven to move axially along the second shaft. Accordingly, the rotating shaft teeth  435  is at the position where they are separated from the toothed ring  441 . In this case, the second handle  44  can rotate freely to realize unlocking. 
     Since the spring  432  is compressed in the unlocked state, when the external force is removed, the spring  432  returns to its original state, returning to the locked state of this embodiment as shown in  FIG.  5   . 
     Embodiment 3 
     As shown in  FIG.  7   , in this embodiment, the inner side of the through-hole in the lug  442  is provided with a retaining groove  443 , and the retaining groove  443  has a depth such that it can accommodate the thicknesses of two one-way bearings  437  (as shown in  FIG.  8   ). The size of the inner contour of the retaining groove  433  conforms to that of the outer contour of the one-way bearings  437 . The pin  433 , the retaining shaft  434 , and the one-way bearing  437  are coaxially arranged to form a second shaft. The two one-way bearings  437  are sheathed on a bearing matching part  436  of the retaining shaft  434 . The rotation directions of the two one-way bearings  437  are opposite. When no external force is applied to the button  431 , the two one-way bearings  437  are in the retaining groove  433 , the second arm  44  is in a locked state, and the spring  432  is compressed. When an external force is applied to the button  431 , not both of the one-way bearings  437  are in the retaining groove  433 , such that the second handle  44  can be rotated in one direction or two directions while in an unlocked state. When the external force is removed, it returns to the locked state again. Compared with Embodiment 2, the advantage of this embodiment is that stepless adjustment can be achieved, such that the second handle  44  can be adjusted to any angle without being restricted by the fit between teeth. 
     Embodiment 4 
     As shown in  FIGS.  9  and  10   , in this embodiment, no special treatment is performed on the inner side of the through-hole in the lug  442 , but at least two raised shaft holes are provided around the through-hole. At the same time, at least one raised shaft  4313  is provided on the retaining shaft  434 . When no external force is applied to the button  431 , due to the action of the spring  432 , the raised shaft  4313  is inserted into the raised shaft hole to realize the locking of the second handle  44 . When an external force is applied to the button  431 , the spring  432  is compressed and drives the retaining shaft  434  to move axially at the same time, and the raised shaft  4313  also exits the raised shaft hole to realize unlocking. When the external force is removed, it returns to the locked state. The advantage of this embodiment is that there is no need to machine the inner side of the through-hole in the lug  442 , thereby reducing the manufacturing difficulty and the production cost. 
     Embodiment 5 
     As shown in  FIG.  11   , in this embodiment, the button  431  and the spring  432  are not used to realize locking and unlocking, but a knob  438  fixedly connected to the pin  433  is used to realize locking and unlocking. When the knob  438  is tightened, the second handle  44  and the first handle  42  are relatively fixed and are in a locked state. When the knob  438  is loosened, the second handle  44  can rotate about the second shaft relative to the first handle  42 , and they are in an unlocked state. 
     Embodiment 6 
     As shown in  FIGS.  12  and  13   , in this embodiment, based on the use of the knob  438 , ball accommodating grooves for accommodating balls  439  and ball springs  4310  are provided in the lug  442 . Ball grooves  4381  are provided on the side of the knob  438  that is close to the lug  442 , and the size of the ball grooves  4381  conforms to that of the balls  439 . In the process of tightening of the knob  438 , the ball grooves  4381  are brought into contact with the balls  439 , and a sound is emitted as a tightening prompt, to confirm that the knob  438  is in a tightened position. 
     Embodiment 7 
     As shown in  FIGS.  14  to  16   , an eccentric cam  4311  and a lever  4312  are used in this embodiment to drive the pin  433  to axially rotate along the second shaft so as to realize the locked and unlocked states. 
     Embodiment 8 
     As shown in  FIG.  17   , in this embodiment, the same locking method by which the toothed ring  441  engages with the rotating shaft teeth  435  in Embodiment 1 is used. The difference from Embodiment 1 is that the positions of the rotating shaft teeth  435  are not changed, so the toothed ring  441  and the rotating shaft teeth  435  will not be separated. A space is provided on the first handle  42  for accommodating a toothed fastener  4314 . The toothed fastener  4314  may be a screw. When locking is desired, the toothed fastener  4314  is fastened such that the rotating shaft teeth  435  are fixed relative to the first handle  42 . Since the rotating shaft teeth  435  engage with the toothed ring  441 , and the toothed ring  441  is fixedly connected to the second handle  44 , the second handle  44  is fixed relative to the first handle  42  in a locked state. When the toothed fastener  4314  is released, the rotating shaft teeth  435  can rotate relative to the first handle  42  and therefore the second handle  44  can also rotate relative to the first handle  42  in an unlocked state. 
     Embodiment 9 
     As shown in  FIG.  18   , this embodiment is similar to Embodiment 8, except that the rotating shaft teeth  435  are fixedly connected to the first handle  42 , and the toothed ring  441  and the lug  442  can move relative to each other. The toothed fastener  4314  is provided on the second handle  44 . When locking is desired, the toothed fastener  4314  is tightened, such that the toothed ring  441  is fixed relative to the second handle  44 . Since the toothed ring  441  engages with the rotating shaft teeth  435 , and the rotating shaft teeth  435  are fixedly connected to the first handle  42 , the second handle  44  is fixed relative to the first handle  42  in a locked state. When the toothed fastener  4314  is released, the toothed ring  441  can rotate relative to the second handle  44 , and therefore the second handle  44  can also rotate relative to the first handle  42  in an unlocked state. 
     Embodiment 10 
     As shown in  FIGS.  19  and  20   , in this embodiment, a third handle  5  is also comprised. The third handle  5  is fixedly connected to the driving mechanism  3 , and may be fixed to the driving mechanism  3 , or may be detachably connected thereto. The first shaft of the first connection mechanism  41  is arranged to be parallel to the main plane, such that when the first handle  42  rotates about the first shaft, it can form a certain included angle with the main plane. This embodiment is suitable for scenarios where the construction space is insufficient. The first handle  42  can drive the second handle  44  to be folded to a certain angle. Preferably, the first handle  42  can form an angle of 90 degrees with the main plane to reduce the overall height of the device as much as possible. In this case, the user can carry out construction by holding the third handle  5 . 
     Embodiment 11 
     As shown in  FIG.  21   , in this embodiment, the base  1  specifically comprises a base body  11  and an adjustable plate  12 . The adjustable plate  12  is provided with a backing plate  122 . The backing plate  122  is in contact with the board material, to reduce the damage to the board material. The backing plate  122  is generally made of a plastic material, and is fixedly connected to the adjustable plate  12  via backing plate screws  123 . In order to ensure that the adjustable plate  12  can provide a stable connection, the adjustable plate  12  is generally a metal die casting. The adjustable plate  12  is provided with an adjustable plate stud  121 , and a rotating disk  112  is provided at the corresponding position of the base body  11 . Inner threads of the rotating disk  112  conform to outer threads of the adjustable plate stud  121 . By rotating the rotating disk  112  to drive the adjustable plate stud  121 , the height of the adjustable plate  12  can be adjusted. The rotating disk  112  is fixed to the base body  11  via a limiting plate  111 , a circlip  113  and a rotating disk bolt  114 . 
     The base body  11  in this embodiment is further provided with a moving mechanism to assist the movement. Specifically, roller brackets  13  and rollers  14  are comprised. The rollers  14  are rotatably fixed to the roller brackets  13 . In order to facilitate packaging and transportation of the device, the moving mechanism needs to be detachable. Therefore, a sliding groove  15  is further provided at each connection between the base body  11  and the moving mechanism in this embodiment, and each of the roller brackets  13  is detachably connected to the base body  11  via the sliding groove  15 . A bracket ball  16  is provided on the roller bracket  13 , and a bracket ball retaining groove  17  is provided at a corresponding position in the sliding groove  15 , so as to realize the limiting and locking of the roller bracket  13  on the sliding groove  15 . 
     More detailed structures of the adjustable plate  12  and the moving mechanism are described in  FIGS.  23  to  26   .  FIGS.  24 ,  25  and  26    are respectively cross-sectional diagrams of the structures at positions B, C and D in  FIG.  23   . 
     Embodiment 12 
     As shown in  FIG.  27   , in this embodiment, two height adjustment camshafts  125  are provided in parallel inside the base. An upper surface of the adjustable plate  12  is attached to outer surfaces of the height adjustment camshafts  125  via four posts and springs. The height adjustment camshaft  125  is cylindrical with unequal radii. Since the upper surface of the adjustable plate  12  comes into contact with the surfaces of the height adjustment camshafts  125 , the height of the bottom of the base changes accordingly as the height adjustment camshaft  125  rotates to different angles. As shown in  FIG.  7   , the height adjustment camshaft  125  used in this embodiment has four curved surfaces, such that the bottom of the base has four different heights. As shown in a, b, c, and d of  FIG.  7   , the height adjustment camshaft  125  is rotated to four different positions, respectively, such that the bottom of the base has the corresponding heights. In other embodiments, the height adjustment camshaft  125  may be provided with a different number of curved surfaces according to actual requirements, so as to achieve the technical effect of adjusting the height of the bottom of the base. 
     Embodiment 13 
     As shown in  FIG.  28   , in this embodiment, ends of the two height adjustment camshafts  125  provided inside the base are respectively provided with driven wheels  1243 . The driven wheels  1243  are configured to be fixed to the height adjustment camshafts  125 . When the driven wheels  1243  are driven by an external force, the height adjustment camshafts  125  can be driven to rotate. In this embodiment, one of the two driven wheels  1243  is connected to the driving wheel  1241  via a connecting rod  1242 , and the other of the two driven wheels  1243  is connected to a height adjustment part  124  via a connecting rod  1242 . The height adjustment part  124  is a knob. The height adjustment part  124  and the driving wheel  1241  have the same size, and are respectively fixed to two ends of a wheel shaft. When a user operates the height adjustment part  124 , that is, when the knob is turned, the height adjustment part  124  and the driving wheel  1241  rotate at the same angular velocity. Under the drive of the connecting rods  1242 , the driven wheel  1243  connected to the height adjustment part  124  and the driven wheel  1241  connected to the driving wheel  1241  rotate in the same direction and at the same angular velocity. The height adjustment camshafts  125  are driven to rotate, so as to adjust the height of the bottom of the base. 
     Embodiment 14 
     As shown in  FIG.  29   , the structures for connecting and driving the height adjustment camshafts  125  different from those of Embodiment 13 are illustrated. In this embodiment, one end of each of the two height adjustment camshafts  125  is provided with a driven gear  1245 . The two driven gears  1245  with the same size and the same number of teeth engage with a driving gear  1244 . A height adjustment part  124  and the driving gear  1244  are respectively fixed to two ends of a wheel shaft. The height adjustment part  124  is a knob. When the user operates the height adjustment part  124 , that is, turning the knob, the driving gear  1244  is driven to rotate. The two driven gears  1245  are driven by the driving gear  1244  to rotate at the same angular velocity but in opposite directions. In this embodiment, the cross sections of the two height adjustment camshafts  125  are symmetrically provided, and therefore in their reverse rotations, it is ensured that the curved surfaces that come into contact with the upper surface of the bottom of the base are the same. 
     The specific preferred embodiments of the invention are described in detail as above. It should be understood that a person of ordinary skill in the art would be able to make various modifications and variations according to the concept of the present invention without involving any inventive effort. Therefore, any technical solution that can be obtained by those skilled in the art by means of logical analysis, reasoning or limited trials on the basis of the prior art and according to the concept of the present invention should be included within the scope of protection of the claims.