GB2474912A

GB2474912A - Strapping device and top plate for holding articles on a pallet

Info

Publication number: GB2474912A
Application number: GB1001148A
Authority: GB
Inventors: Zuocheng Qian; Kai Gong; Yongzhi Qui; Zhengguo Du
Original assignee: Shanghai Horen Science and Technology Co Ltd
Current assignee: Shanghai Horen Science and Technology Co Ltd
Priority date: 2009-08-21
Filing date: 2010-01-25
Publication date: 2011-05-04
Anticipated expiration: 2030-01-25
Also published as: GB201001148D0; GB2474912B

Abstract

The present invention relates to a strapping device and a top plate for holding articles on a pallet. The strapping device being provided on a bottom plate 10 and having a tightening/ clamping means 44 for tightening/ clamping a strap 2, a driving means 45 for moving the clamping/ tightening means 44 and a spring means 7 for retracting the strap 2 when the strap 2 is released by the clamping/ tightening means 44. The driving means 45 consists of a spindle 13 which is rotatably supported by the bottom plate 10; a flexible member winding disk 30 which is provided on the spindle 13 and rotatable with the spindle 13 synchronously; and a set of pulleys 24, 25, 26. A flexible member 27 is directed from the flexible member winding disk 30, via the set of pulleys 24, 25, 26, to the tightening/ clamping means 44, wherein when the strap 2 is to be tightened/ clamped, rotation of the spindle 13 is transformed into movement of the tightening/ clamping means 44 by means of the flexible member 27 so that the tightening/ clamping means 44 tightens/ clamps the strap 2, a protruding end of which may be fixed to a pallet. Preferably the strapping device includes an overload clutch 16 to prevent over tightening/ clamping of the tightening/ clamping means 44. The spindle 13 may be turned by a handle 11. The tightening/ clamping means 44 preferably comprises a snap plate (fig 6, 7, ref 4) which rotates downward so as to clamp the strap 2 passing under it.

Description

STRAPPING DEVICE AND

TOP PLATE FOR HOLDING ARTICLES ON A PALLET

TECHNICAL FIELD

The present invention relates to a top plate for holding articles on a pallet and a strapping device therein, the strapping device comprising a tightening means for tightening a strap, a driving means for moving the tightening means and a spring means for retracting the strap when the strap is released by the tightening means.

BACKGROUND ART

A Chinese patent application for invention CN1717356A discloses "a top plate for holding articles on a pallet", wherein the top plate comprises a box body. A strap for strapping articles passes through a grooved cross arm in the box body, the grooved cross arm being disposed between a cylinder for taking up the strap and a hook having two teeth for hooking onto the bottom side of the pallet. The strap is tightened by a linkage mechanism between the cross arm and a control level. The control level oscillates between a non-operating position and an operating position, so as to rotate the cross arm and therefore winding the strap onto the cross arm. The linkage mechanism comprises a cable wire, a spindle with a ratchet, a ratchet driving pawl mounted in the control level, a latching pawl mounted in the control level and a means which can be manually operated to disengage the driving pawl from the ratchet. One end of the cable wire is fixed on the spindle and the other end of the cable wire is fixed on a guiding wheel which is provided on one end of the cross arm. The guiding wheel rotates with the cross arm. When the control level is moved from the non-operating position to the operating position, by means of the transmission between the ratchet driving pawl and the ratchet, the cable wire is unwound from the guiding wheel, while the cross arm is rotated so as to wind the strap thereonto. The aforementioned means which can be manually operated to disengage the driving pawl from the ratchet comprises a slider which moves the driving pawl and the head of which is provide with two laterally protruding portions which are engaged with a sloping means when the slider slides toward the driving pawl, the sloping means being linked to the ratchet driving pawl so as to allow the ratchet driving paw! to engage with or disengage from the ratchet. The device has no safety means against overload. If an excessively large force is applied on the strap, the strapped articles will be damaged or the strap will broken, therefore the reduced safety will also directly compromise the service life of the device.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a strapping device for binding articles on a pallet and linkage means of the strapping device, so as to prevent from occurrence of an accident such as collapsing, broken and the like of the articles on the pallet during transportation of the articles and also facilitate their control.

In order to achieve the above-mentioned object, the present invention provides a strapping device provided on a bottom plate, comprising a tightening means for tightening a strap, a driving means for moving the tightening means and a spring means for retracting the strap when the strap is released by the tightening means, wherein the driving means comprises: a spindle which is rotatablely supported by the bottom plate; a flexible member winding disk which is provided on the spindle and rotatable with the spindle synchronously; a set of pulleys; a flexible member which is directed from the flexible member winding disk, via the set of pulleys, to the tightening means, wherein when the strap is to be tightened, rotation of the spindle is transformed into movement of the tightening means by means of the flexible member so that the tightening means tightens the strap a protruding end of which has been fixed.

The strapping device further comprises an overload clutch and the flexible member winding disk fits over the spindle, the overload clutch comprising a drive portion and a driven portion, the flexible member winding disk being connected to or integrated with the driven portion, the drive portion being rotatable with the spindle synchronously, the drive portion and the driven portion being engaged, wherein when the torque transmitted by the drive portion and the driven portion exceeds a nominal load of the overload clutch, there is a relative slip between the drive portion and the driven portion so that the driving force of the spindle cannot be transmitted to the flexible member.

In the strapping device, the drive portion of the overload clutch has a plurality of ribs, the roots of which are distributed on a circumference and connected to form an annular body by which the drive portion fits over the spindle, the plurality of ribs being oblique in the same direction along the circumference, and the driven portion of the overload clutch is a ratchet provided with teeth on its outer circumferential surface and a plurality of slots on its inner circumferential surface, wherein the ratchet fits over the drive portion so that the plurality of slots abutting against the plurality of ribs respectively so as to achieve one-way transmission between the drive portion and the driven portion while when the transmitted torque exceeds the nominal load of the overload clutch, the plurality of ribs deforms elastically so that there is a relative slip between the drive portion and the driven portion, and with the ratchet being engaged with a paw! provided on the bottom plate, when the spindle rotates forwardly so as to tighten the strap, there is a relative slip between the ratchet and the pawl.

The strapping device further comprises a toothed one-way clutch comprising a drive wheel and a driven wheel with teeth provided on a disk face of the drive wheel and a disk face of the driven wheel, the disk face with teeth of the drive wheel and the disk face with teeth of the driven wheel being opposite to each other so that the drive wheel and the driven wheel achieve one-way transmission by means of the engagement of the teeth provided on the opposite disk faces of the drive wheel and the driven wheel, wherein both of the drive wheel and the driven wheel fits over the spindle, the driven wheel being fixedly connected to or integrated with the drive portion of the overload clutch and the drive wheel being connected to the spindle by a pin which is movable in an axial channel of the drive wheel, so that when the spindle rotates forwardly so as to tighten the strap, there is one-way transmission between the drive wheel and the driven wheel.

The strapping device further comprises a releasing means for releasing the engaged toothed one-way clutch and the engaged ratchet and pawl.

In the strapping device, the releasing means comprises a boss provided on the drive wheel and a block provided on the spindle adjacent to the flexible member winding disk, the boss of the drive wheel having a bevel surface on one side and one end of the paw! being fixed to the bottom plate, wherein when the spindle rotates reversely through an angle, the block on the spindle contacts with the other end of the pawl and thereby the pawl bends so as to disengage from the ratchet and at the same time the bevel surface of the boss of the drive wheel contacts with a guider fixed on the bottom plate, which during the reverse rotation of the spindle, slips with respect to the guider so that the guider applies a force in the axial direction of the spindle to the drive wheel under the action of which the drive wheel moves in the axial direction of the spindle so that the drive wheel disengages from the driven wheel with a spring being pressed on the other side of the drive wheel.

In the strapping device, a stop boss is further provided on the drive wheel for preventing the rotated angle of the spindle during the forward or reverse rotation from being excessively large.

The strapping device further comprises a handle which is fixed connected to the spindle and a spring is connected to the end of the spindle away from the handle and is provided in a spring holder on the bottom plate, a button being provided on the handle so that when the handle is in a stowing state, the button on the handle is locked by a latch on the bottom plate and when the button is pressed so as to disengage from the latch on the bottom, under the action of the elastic force of the spring, the spindle and the handle are ejected so that the handle is transferred from the stowing state to an operating state for being grasped.

In the strapping device, the driven wheel of the toothed one-way clutch and the drive portion of the overload clutch are formed on a cylinder with an annular rib provided on the bore wall of the cylinder and fit over the spindle via the cylinder.

In the strapping device, the tightening means comprises a snap plate seat slideably provided on the bottom plate, a snap plate pivoted to the snap plate seat and provided with a snap plate return spring for returning the snap plate at the pivoted portion and a snap plate striker provided on the bottom plate, the flexible member being connected to the snap plate seat and a space for the strap to pass therethrough being provided between the snap plate and the snap plate seat, wherein when the strap is not to be tightened, the snap plate is supported by the snap plate striker at a position where it is away from the strap and when the strap is to be tightened, the snap plate separates from the snap plate striker and under the action of the spring force provided by the snap plate return spring, the snap plate rotates to a position where it presses the strap against the bottom plate.

In the strapping device, the set of pulleys comprises a movable pulley provided on the snap plate seat.

In the strapping device, a snap plate seat return spring is provided between the snap plate seat and the bottom plate so that once a tractive force of the flexible member acting on the snap plate seat disappears, the snap plate seat is pulled back by the snap plate seat return spring to an initial position where the strap can move freely.

In the strapping device, the snap plate slants toward a direction in which the strap is retracted by the spring means with respect to the strap passing under it, forming an angle with respect to a direction vertical to the strap and during the tightening of the strap, a bottom edge of the snap plate rotates toward a direction in which the angle is reduced by means of the friction force of the strap acting on the snap plate due to the relative movement between the strap and the snap plate seat so as to lock the strap securely on the snap plate seat.

In the strapping device, an antislip rib and a latch are provided on the bottom end of the snap plate for pressing the strap, the latch being the bottom edge of the snap plate, and an antislip groove is provided on the snap plate seat, wherein when the strap is tightened, the antislip rib presses the strap into the antislip groove while the latch presses against the strap securely, and a stop block is further formed on the snap plate seat, for preventing the snap plate from rotating beyond the position where the snap plate is perpendicular to the strap under it and disengaging from the strap during the tightening of the strap.

In the strapping device, the flexible member is a cable wire.

The present invention provides a top plate for holding articles on a pallet, comprising a bottom plate, at least two strapping devices provided on the bottom plate, a cover for covering the bottom plate and at least two straps respectively provided on the at least two strapping devices, the at least two straps extend out of the bottom plate through openings on two opposite sides of the bottom plate, wherein each strapping device is the strapping device according to any one of the preceding strapping devices.

In the top plate, stacking ribs are provided on the four corners of the cover body respectively so as to prevent articles from collapsing effectively.

The advantageous effects of the present invention are as follows: 1. A cover provided with the strapping device according to the present invention can effectively prevent from occurrence of an accident such as collapsing, broken and the like of articles during transportation of the articles.

2. The safety means provided in the driving means according to the present invention can effectively prevent the strap from being tightened excessively so as to cause an accident such as broken strap or damaged means.

3. The strapping device according to the present invention is simple in structure, has a prominent effect, is adapted to mass production and is suitable to be widely used in the arts such as materials circulation.

4. The cover according to the present invention has protruded stacking ribs (or protruded edges) on the four top corners which facilitate the stacking of the pallet and allow the stacked articles to be formed into an integrated body which is not easy to move or disengage.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic overall structural view of a strapping device according to the present invention.

Fig. 2 is a schematic overall structural view of a top plate provided with the strapping device according to the present invention.

Fig. 3 is a schematic structural view of a tightening means and a driving means according to the present invention.

Fig. 4 is a operating principle view of the tightening means and the driving means according to the present invention.

Fig. 5 is a schematic structural view of the tightening means according to the present invention.

Fig. 6 is a schematic operating principle view of the tightening de vice according to the present invention, wherein the strap is pressed.

Fig. 7 is a schematic operating principle view of the tightening means according to the present invention, wherein the strap can move freely.

Fig. 8 is a schematic assembly view of an overloaded clutch according to the present invention.

Fig. 9 is a schematic operating principle view of the overloaded clutch according to the present invention.

Fig. 10 is a schematic installation view of a driven wheel of a toothed one-way clutch and a spindle according to the present invention.

Fig. 11 is a partial enlarged view of position A in Fig. 10.

Fig. 12 is a schematic structural view of the toothed one-way clutch of the driving means according to the present invention, wherein the toothed one-way clutch is in an engaged state.

Fig. 13 is a schematic structural view of the toothed one-way clutch of the driving means according to the present invention, wherein two portions of the toothed one-way clutch have not been disengaged completely.

Fig. 14 is a schematic structural view of the toothed one-way clutch of the driving means according to the present invention, wherein the two portions of the toothed one-way clutch have been disengaged completely.

Fig. 15 is a schematic structural view of the ratchet of the driving means according to the present invention.

Fig. 16 is a schematic operating principle view of the driving means according to the present invention, wherein the toothed one-way clutch is in an engaged state.

Fig. 17 is another schematic operating principle view of the linkage means according to the present invention, wherein the two portions of the toothed one-way clutch are disengaged.

Fig. 18 is a schematic structural view of the drive wheel of the toothed one-way clutch of the driving means according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in Figs. 1, 3 and 4, a driving means 45 provided on a bottom plate 10 comprises a winding handle or a handle 11, a spindle 13, a toothed one-way clutch 14-1 and an overload clutch 14-2. The winding handle 11 is provided on an outer end of the spindle 13.

As shown in Figs. 12-14 and 16-17, the toothed one-way clutch 14-1 comprises a drive wheel 47 and a driven wheel 48. Teeth are provided on the opposite disk faces of the drive wheel 47 and the driven wheel 48, through which the two wheels achieve one-way transmission.

Further as shown in Figs. 8-9 and 15, the overload clutch 14-2 comprises a drive portion 15 and a driven portion 16. The drive portion 15 has a plurality of ribs 35, the roots of which are distributed on a circumference and connected to form an annular body 35-2. The drive portion 15 fits over the spindle 13 by the annular body 3 5-2. The ribs 35 are oblique in the same direction along the circumference. The ribs 35 are shaped like lobs.

The driven portion 16 of the overload clutch 14-2 is a ratchet with teeth on its outer circumferential surface. A plurality of slots 34 are provided on the inner circumferential surface of the ratchet 16. The ratchet 16 fits over the drive portion 15, with the plurality of slots 34 abutting against the plurality of ribs 35-1, so as to achieve a one-way transmission between the drive portion 15 and the driven portion 16. When the transmitted torque exceeds a nominal load of the overload clutch 14-2, the ribs 35-1 deform elastically so that there is a relative slip between the drive portion 15 and the driven portion 16, causing the ratchet 16 to engage with a pawl 28 provided on the bottom plate 10. When the spindle 13 rotates forwardly so as to tighten a strap 27, there is a relative slip between the ratchet 16 and the pawl 28, which prevents articles being strapped excessively tightly by the strap.

As shown in Fig. 3, a channel 130 is provided on the spindle 13 and a pin 54 movable along the channel is connected to the drive wheel 47 so that the drive wheel 47 is connected to the spindle 13, allowing the drive wheel 47 to move axially along the spindle 13, but not allowing relative rotation between the drive wheel 47 and the spindle 13. The length of the channel 130 is equal to the length of the winding handle 11 extending from the bottom plate 10. The driven wheel 48 is rotatablely mounted on the spindle 13. As shown in Figs. 4, 10 and 12-14, the drive portion 15 of the overload clutch 14-2 is fixedly connected to the driven wheel 48, through the drive portion 15 can also be integrated with the driven wheel 48.

As shown in Figs. 1, 3-4 and 16-17, a cable wire winding disk 30 is integrated with the ratchet 16 and is provided with a groove 300 for winding the cable wire. A cable wire 27 is directed from the winding disk 30, via a fixed pulley 25, a fixed pulley 26 and a movable pulley 24, to a tightening means 44.

The bottom plate 10 is provided with a support for supporting the spindle 13 and positioning the components on the spindle 13. The particular arrangement of the support can be determined as desired. For example, one semicircle hole is provided in the support of the bottom plate 10 and the other semicircle hole is provided in a cover body 19 (as shown in Fig. 2), with the two semicircle holes forming a circle hole for the spindle to pass through, the spindle being rotatable in the circle hole.

A releasing means for releasing the engaged toothed one-way clutch and the engaged ratchet and pawl according to the present invention will be explained with reference to Figs. 3-4, 8-9 and 12-18 hereafter.

As shown in Figs. 12-14 and 18 firstly, the drive wheel 47 is provided with a boss 53 on its outer periphery and the boss 53 has a bevel surface 530 on one side. When the drive wheel 47 rotates counterclockwise (i.e., the spindle rotates reversely), by means of a guider 56 on the corresponding area of the bottom plate 10, the boss 53 causes the drive wheel 47 to move away from the driven wheel 48 so as to be released from the engagement with the driven wheel 48. The drive wheel 47 is further provided with a stop boss 54 on its outer periphery and the stop boss 54 can prevent the winding handle 11 from being rotated counterclockwise excessively.

As shown in Fig. 4, a return spring 32 is provided between the winding handle 11 and the toothed one-way clutch 14 and the elastic force provided by the return spring 32 can ensure the effective engagement of the two portions (the drive wheel 47 and the driven wheel 48) of the toothed one-way clutch 14.

Further as shown in Figs. 3-4 and 15, a block 29 is mounted on the spindle 13 adjacent to the cable wire winding disk 30 and rotates with the spindle 13. When the block 29 rotates to the bottom plate 10 side, a pawl releasing block 36 is provided on a corresponding area on the bottom plate 10 (the pawl releasing block 36 may be formed as a portion of the pawl 28). One end of the pawl 28 is fixed on the bottom plate 10 and the other end of the pawl 28 is fixedly connected to the pawl releasing block 36. The area corresponding to the pawl releasing block 36 on the bottom plate 10 is hollowed out.

When the spindle 13 rotates reversely through an angle, the block 29 acts on the pawl releasing block 36, the paw! 28 being bent toward the bottom plate so that the paw! 28 no longer acts on the ratchet 16, which is released in this state. The block 29 and the boss 53 of the drive wheel 47 are consistent with each other in the axial direction, that is, when the spindle 13 rotates reversely through an angle, the block 29 on the spindle 13 contacts with the pawl releasing block 36 on the other end of the paw! 28 and thus the pawl 28 is bent so as to disengage from the ratchet 16 and at the same time the bevel surface 530 of the boss 53 of the drive wheel 47 contacts with the guider 56 fixed on the bottom plate 10.

During the reverse rotation of the spindle 13, the bevel surface 530 of the boss 53 slips with respect to the guider 56 so that the guider 56 applies a force in the axial direction of the spindle 13 to the drive wheel 47. Under the action of the force, the drive wheel 47 moves in the axial direction of the spindle 13 so that the drive wheel 47 disengages from the driven wheel 48.

As shown in Figs. 1 and 3, a button 12 is provided on the winding handle 11 and a latch 49 is provided on the bottom plate 10 at a position corresponding to the button 12. A spring holder 50 is provided at the end of the spindle 13 away from the winding handle 11 and a handle ejecting spring 31 is mounted in the spring holder 50. If the button 12 is pressed so as to release the latch 49, under the action of the handle ejecting spring 31, the winding handle 11 will be ejected.

As shown in Fig. 3, one end of the cable wire 27 is fixed on the cable wire winding disk 30 and is wound in the groove of the cable wire winding disk 30, while the other end of the cable wire 27 runs over the fixed pulley 25, the fixed pulley 26 and the movable pulley 24 and is fixed on the bottom plate 10. The fixed pulley 25 and the fixed pulley 26 are fixed on the bottom plate 10.

As shown in Fig. 1, a winding disk 6 for taking up and storing a strap 2 is provided on the bottom plate 10. The free end of the strap 2 is connected to a hook 1, which can hook onto a frame of a pallet (not shown). A winding disk fixing pin 9 and a spiral spring 7 around the fixing pin 9 as its central shaft are provided on the winding disk 6. The winding disk 6 is covered by a winding disk cover 8.

As shown in Figs. 4-7, a tightening means 44 is also provided on the bottom plate 10.

When the hook 1 hooks onto the frame of the pallet under articles, the tightening means 44 serves to tighten the strap 2. The tightening means 44 comprises a snap plate striker 38 which is integrated with the bottom plate 10 and a snap plate 4 which is mounted on a snap plate seat 3 by means of a snap plate pin 43. A snap plate spring 23 fits over the snap 23 plate pin 43. One end of the snap plate spring 23 acts on the snap plate 4 and the other end of the snap plate spring 23 acts on the snap plate seat 3. Under the action of the snap plate spring 23, the snap plate 4 can rotate around the snap plate pin 43 relatively. Once the snap plate 4 is released from the pushing action of the snap plate striker 38, under the action of the snap plate spring 23, the snap plate 4 rotates downward so as to clamp the strap 2 passing under it. The snap plate seat 3 can move in a square frame area on the bottom plate 10. A movable pulley 24 and a snap plate return spring 5 are provided on the -10 -snap plate seat 3. One end of the snap plate return spring 5 is fixedly connected to the snap plate seat 3 and the other end of the snap plate return spring 5 is fixed to the bottom plate 10. The tightening means 44 further comprises an antislip plate 39 provided on the snap plate seat 3, an antislip rib 40 at the bottom end of the snap plate 4 and a latch 42.

An antislip groove 41 is provided on the antislip plate 39. As shown in Fig. 6, when the snap plate 4 separates from the snap plate striker 38, under the action of the snap plate spring 23, the snap plate 4 rotates downward so that the antislip rib 40 enters into the antislip groove 41 so as to press the strap 2 into the antislip groove 41 and the bottom edge of the latch 42 is also pressed onto the strap 2 so that the snap plate 4 can press against the strap 2 passing under it more effectively. As shown in Figs. 6 and 7, when the snap plate seat 3 moves leftward, the strap 2 moves rightward with respect to the snap plate 4 so as to apply a rightward friction force to the bottom end of the snap plate 4, therefore, the snap plate 4 obtaining a counterclockwise moment. Since the snap plate 4 slants toward the moving direction of the snap plate seat 3, i.e., leftward in the figure, under the action of the counterclockwise moment, the snap plate 4 rotates counterclockwise so that with the leftward movement of the snap plate seat 3, the latch 42 at the bottom of the snap plate 4 locks the strap 2 onto the snap plate seat 3. In order to prevent the counterclockwise rotating angle of the snap plate 4 being too large, i.e., beyond the position where the snap plate 4 is perpendicular to the strap 2, a stop block 47 is also provided on the snap plate seat 3, as shown in Fig. 6. The stop block 47 serves to prevent the snap plate 4 from rotating beyond the position where the snap plate 4 is perpendicular to the strap 2 under the action of the friction force of the strap 2.

As shown in Fig. 2, in the top plate for holding articles on a pallet, a cover comprises a cover body 19 as well as a hand-hold steel tube 21 and a notch 22 provided on the cover body 19. At least the aforementioned strapping device is disposed between the cover body 19 and the bottom plate 10.

Stacking ribs 20 are provided on the corners of the cover body 19 so as to prevent articles from collapsing more effectively.

Hereafter, the operation of the strapping device or the top plate for holding articles on a pallet according to the present invention will be explained.

The button 12 is pressed so that under the action of the handle ejecting spring 31, the -11 -winding handle 11 is ejected. At this time, the snap plate striker 38 acts on the snap plate 4 so that the strap 2 can pass through the tightening means 44 freely. The strap 2 is pulled out, the frame of the pallet under articles being hooked by the hook 1 and the winding handle 11 is rotated clockwise. By means of the engagement of the toothed drive wheel 47 and the driven wheel 48, the ratchet 16 is rotated so that the cable wire 27 is wound in the groove of the cable wire winding disk 30. By means of the pulling of the cable wire 27, the snap plate seat 3 moves away from the snap plate striker 38 so that the snap plate striker 38 no longer acts on the snap plate 4. The snap plate 4 rotates downward, clamping the strap 2 passing under it, not allowing the relative movement between the strap 2 and the snap plate seat 3, so that the strap 2 and the snap plate seat 3 moves away from the snap plate striker 38 together. The operation of tightening the strap 2 is done.

When the winding handle 11 is rotated counterclockwise through an angle slightly greater than 90°, the drive wheel 47 moves away from the driven wheel 48 so as to disengage from the driven wheel 48. At this time, the boss 53 for releasing the block acts on the pawl releasing block 36 so that the pawl 28 no longer acts on the ratchet 16. In this state, the ratchet 16 is released and at this time the cable wire 27 does not act on the snap plate seat 3. Under the action of the snap plate return spring 5, the snap plate seat 3 moves toward the snap plate striker 38 and the snap plate striker 38 acts on the snap plate 4 again.

Under the action of the spiral spring 7, the strap 2 is taken up rapidly so that the hook 1 is blocked at the exit of the strap 2 on the bottom plate 10.

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Claims

CLAIMS1. A strapping device provided on a bottom plate, comprising a tightening means for tightening a strap, a driving means for moving the tightening means and a spring means for retracting the strap when the strap is released by the tightening means, wherein the driving means comprises: a spindle which is rotatablely supported by the bottom plate; a flexible member winding disk which is provided on the spindle and rotatable with the spindle synchronously; a set of pulleys; a flexible member which is directed from the flexible member winding disk, via the set of pulleys, to the tightening means, wherein when the strap is to be tightened, rotation of the spindle is transformed into movement of the tightening means by means of the flexible member so that the tightening means tightens the strap, a protruding end of which has been fixed.
2. The strapping device according to claim 1, wherein it further comprises an overload clutch and the flexible member winding disk fits over the spindle, the overload clutch comprising a drive portion and a driven portion, the flexible member winding disk being connected to or integrated with the driven portion, the drive portion being rotatable with the spindle synchronously, the drive portion and the driven portion being engaged, wherein when a torque transmitted by the drive portion and the driven portion exceeds a nominal load of the overload clutch, there is a relative slip between the drive portion and the driven portion so that the driving force of the spindle cannot be transmitted to the flexible member.
3. The strapping device according to claim 2, wherein the drive portion of the overload clutch has a plurality of ribs, the roots of which are distributed on a circumference and connected to form an annular body by which the drive portion fits over the spindle, the plurality of ribs being oblique in the same direction along the circumference, and the driven portion of the overload clutch is a ratchet provided with teeth on its outer circumferential surface and a plurality of slots on its inner circumferential surface, wherein the ratchet fits over the drive portion so that the plurality of slots abut against the plurality of ribs so as to achieve one-way transmission between the drive portion and the driven portion, while when the transmitted torque exceeds the -13 -nominal load of the overload clutch, the plurality of ribs deform elastically so that there is a relative slip between the drive portion and the driven portion, and with the ratchet being engaged with a pawl provided on the bottom plate, when the spindle rotates forwardly so as to tighten the strap, there is a relative slip between the ratchet and the pawl.
4. The strapping device according to claim 3, wherein it further comprises a toothed one-way clutch comprising a drive wheel and a driven wheel with teeth provided on a disk face of the drive wheel and a disk face of the driven wheel, the disk face with teeth of the drive wheel and the disk face with teeth of the driven wheel being opposite to each other so that the drive wheel and the driven wheel achieve one-way transmission by means of the engagement of the teeth provided on the opposite disk faces of the drive wheel and the driven wheel, wherein both of the drive wheel and the driven wheel fits over the spindle, the driven wheel being fixedly connected to or integrated with the drive portion of the overload clutch, the drive wheel being connected to the spindle by a pin which is movable in an axial channel of the drive wheel, so that when the spindle rotates forwardly so as to tighten the strap, there is one-way transmission between the drive wheel and the driven wheel.
5. The strapping device according to claim 4, wherein, it further comprises a releasing means for releasing the engaged toothed one-way clutch and the engaged ratchet and pawl.
6. The strapping device according to claim 5, wherein the releasing means comprises a boss provided on the drive wheel and a block provided on the spindle adjacent to the flexible member winding disk, the boss of the drive wheel having a bevel surface on one side and one end of the paw! being fixed to the bottom plate, wherein when the spindle rotates reversely through an angle, the block on the spindle contacts with the other end of the paw! and thereby the paw! bends so as to disengage from the ratchet and at the same time the bevel surface of the boss of the drive wheel contacts with a guider fixed on the bottom plate, which during the reverse rotation of the spindle, slips with respect to the guider so that the guider applies a force in the axial direction of the spindle to the drive wheel under the action of which the drive wheel moves in the axial direction of the spindle so that the drive wheel disengages from the driven wheel with a spring being pressed on the other side of the drive wheel.

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7. The strapping device according to claim 6, wherein a stop boss is further provided on the drive wheel, for preventing the rotated angle of the spindle during the forward or reverse rotation from being excessively large.
8. The strapping device according to claim 4, wherein it further comprises a handle which is fixedly connected to the spindle and a spring is connected to the end of the spindle away from the handle and the spring is provided in a spring holder on the bottom plate, a button being provided on the handle so that when the handle is in a stowing state, the button on the handle is locked by a latch on the bottom plate and when the button is pressed so as to disengage from the latch on the bottom plate, under the action of the elastic force of the spring, the spindle and the handle are ejected so that the handle is transferred from the stowing state to an operating state for being grasped.
9. The strapping device according to claim 4, wherein the driven wheel of the toothed one-way clutch and the drive portion of the overload clutch are formed on a cylinder with an annular rib on its bore wall and fit over the spindle via the cylinder.
10. The strapping device according to claim 1, wherein the tightening means comprises a snap plate seat slideably provided on the bottom plate, a snap plate pivoted to the snap plate seat and provided with a snap plate return spring for returning the snap plate at the pivoted portion and a snap plate striker provided on the bottom plate, the flexible member being connected to the snap plate seat and a space for the strap to pass there through being provided between the snap plate and the snap plate seat, wherein when the strap is not to be tightened, the snap plate is supported by the snap plate striker at a position where it is away from the strap and when the strap is to be tightened, the snap plate separates from the snap plate striker and under the action of the spring force provided by the snap plate return spring, the snap plate rotates to a position where it presses the strap against the bottom plate.
11. The strapping device according to claim 10, wherein the set of pulleys comprises a movable pulley provided on the snap plate seat.
12. The strapping device according to claim 10, wherein a snap plate seat return spring is provided between the snap plate seat and the bottom plate so that once a tractive force of the flexible member acting on the snap plate seat disappears, the snap plate seat is pulled back by the snap plate seat return spring to an initial position where the strap can -15 -move freely.
13. The strapping device according to claim 10, wherein the snap plate slants toward a direction in which the strap is retracted by the spring means with respect to the strap passing under it, forming an angle with respect to a direction vertical to the strap and during the tightening of the strap, a bottom edge of the snap plate rotates toward a direction in which the angle is reduced by means of the friction force of the strap acting on the snap plate due to the relative movement between the strap and the snap plate seat, so as to lock the strap securely on the snap plate seat.
14. The strapping device according to claim 13, wherein an antislip rib and a latch are provided on the bottom end of the snap plate for pressing the strap, the latch being the bottom edge of the snap plate and an antislip groove is provided on the snap plate seat, wherein when the strap is tightened, the antislip rib presses the strap into the antislip groove while the latch presses against the strap securely, and a stop block is further formed on the snap plate seat for preventing the snap plate from rotating beyond the position where the snap plate is perpendicular to the strap under it and disengaging from the strap during the tightening of the strap.
15. The strapping device according to claim 1, wherein the flexible member is a cable wire.
16. A top plate for holding articles on a pallet, comprising a bottom plate, at least two strapping devices provided on the bottom plate, a cover for covering the bottom plate and at least two straps respectively provided on the at least two strapping devices, the at least two straps extend out of the bottom plate through openings on two opposite sides of the bottom plate, wherein each strapping device is a strapping device according to any one of claims 1-15.
17. The top plate for holding articles on a pallet according to claim 16, wherein stacking ribs are provided on the four corners of the cover body respectively so as to prevent articles from collapsing effectively.-16 -