A boxcutter includes a handle, a blade and a holder. The handle includes a bump on an internal face. The blade is insertable in the handle. The holder is moveable in the handle between a front position to extend a front section of the blade from the handle and a rear position to insert the blade entirely in the handle. The holder includes a carrier and an elastic leaf. The carrier includes a flat space for receiving a rear section of the blade. The elastic leaf includes a rear section connected to the carrier and a front section formed with a lever and a latch. The lever extends over the carrier and the latch extends in the cutout. When the holder is in the front position, the lever abuts against the bump to deform the elastic leaf to move the latch from the cutout.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a boxcutter and, more particularly, to a boxcutter that allows easy replacement of a used blade with a new blade.

2. Related Prior Art

Taiwanese Patent No. 297319 discloses a boxcutter including a blade13, a blade holder and a handle. The blade13is inserted in and extensible from the handle, which includes two shells11and12. The blade holder includes a knob20, a catch21, a compression spring22and a threaded bolt23. The knob20is located out of the handle. The catch21is movable in the handle. The threaded bolt23includes a threaded section inserted in a screw hole26made in the catch21and an enlarged head located out of the handle and abutted against the knob20. The compression spring22receives the threaded section of the threaded bolt23and is compressed between the handle and the catch21. Thus, the compression spring22tends to press the catch21on the blade13so that two ribs24of the catch21are inserted in two cutouts15made in the blade13. Thus, a rear section of the blade13is kept in the handle while a front section of the blade13is extended from the handle for use. Now, the knob20is located at an angle on the handle so that the handle is located between feet27extending from the knob20.

To replace the blade13with a new one, the knob20is lifted from the handle to move the ribs24from the cutouts15, thereby allowing the blade13to be detached from the handle. To facilitate insertion of a rear section of a new blade into the handle, the knob is rotated to another angle on the sell so that the feet27stand on the handle to keep the ribs24out of the cutouts15.

It should be noted that the front section of the blade13is extended from the handle while the rear section of the blade13is kept in the handle. The front section of the blade13includes a sharp tip that imposes a potential danger for humans.

SUMMARY OF INVENTION

It is the primary objective of the present invention to provide a safe and convenient boxcutter.

To achieve the foregoing objective, the boxcutter includes a handle, a blade and a holder. The handle includes a bump on an internal face. The blade is insertable in the handle. The holder is moveable in the handle between a front position to extend a front section of the blade from the handle and a rear position to insert the blade entirely in the handle. The holder includes a carrier and an elastic leaf. The carrier includes a flat space for receiving a rear section of the blade. The elastic leaf includes a rear section connected to the carrier and a front section formed with a lever and a latch. The lever extends over the carrier and the latch extends in the cutout. When the holder is in the front position, the lever abuts against the bump to deform the elastic leaf to move the latch from the cutout.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring toFIGS.1and8, a boxcutter10includes a handle11, a blade47and a holder60according to the preferred embodiment of the present invention. The blade47includes a front section extended from the holder60and a rear section inserted in the holder60. The holder60is movable between a front position and a rear position. In the front position, the holder60extends the front section of the blade47from the handle11. In the rear position, the holder60inserts the front section of the blade47in the handle11.

The handle11includes an open (front) end15and a closed (rear) end16. In comparison with the closed end16, the open end15is located near an object being cut by the boxcutter10. The handle11includes a space12in an upper portion located closer to the open end15than to the closed end16. A button50and a switch are located in the space12. The switch18is translatable in and along the space12.

Preferably, the handle11includes two shells13and14connected to each other. An internal side of the shell13is directed at an internal side of the shell14. Each of the shells13and14includes a front end corresponding the open end15and a rear end corresponding to the closed end16.

Referring toFIGS.2through6, the shell13includes a connector21in the form of a hook including a right portion formed on an upper face of the shell13and a left portion inserted in a recess31made in an upper face of the shell14when the handle11is assembled. The shell14includes a connector32in the form of a hook including a left portion formed on the upper face of the shell14and a right portion inserted in recess22made in the upper face of the shell13. The left portion of the connector21is engaged with the right portion of the connector32to keep the shells13and14in contact with each other. Alternatively, the connector32can be formed on the shell13and the recess22made in the shell14, and the recess31can be made in the shell13and the connector21formed on the shell14.

On the upper face, the shell13further includes a protrusion23and a platform42. The protrusion23is located between the recess22and the platform42. The protrusion23includes a cavity24in communication with a cutout27. The cutout27is made in a shoulder26formed on an internal side of the protrusion23. A bore25is made between the cavity24and the platform42.

Similarly, on the upper face, the shell14further includes a protrusion33. Preferably, the protrusion33is made in one piece with the connector32. The combination of the protrusion33with the connector32is located between the recess31and a platform43formed on the upper face of the shell14. The protrusion33includes a cavity34in communication with a cutout37. The cutout37is made in a shoulder36formed on an internal side of the protrusion33. A bore35is made between the cavity34and the platform43. An edge of the shell14is made with an elongated recess41, adjacent to the platform43. Several ribs40are formed on the internal side of the shell14to reinforce the shell14. A bump44is also formed on the internal side of the shell14. The bump44includes a vertical facet45and a slant facet46. The slant facet46descends to the internal side of the shell14from a rear end of the vertical facet45.

The button50includes a major portion51, two fins52, two upright portions53, a hole54and a hook55. The fins52extend from two lateral sides of the major portion51. The upright portions53extend on the lateral sides of the major portion51. Each of the fins52and a corresponding one of the upright portions53form an inverted T-shaped portion. However, in another embodiment, each of the fins52is not connected to the corresponding one of the upright portions53. The hole54is made in a lower face of the major portion51. The hook55extends from a rear face of the major portion51.

The protrusions23and33are in contact with each other so that the cavities24and34become one for receiving the major portion51. The bores25and35become one for receiving the hook55. A compression spring56includes an end inserted in the hole54and another end in contact with the floors of the cavities24and34. The compression spring56is compressed between the button50and the handle11, thereby tending to lift the button50from the handle11. The hook55includes a free end normally located above the platforms42and43. The shoulders26and36form an internal flange for abutment against the fins52. Thus, the button50is kept on the handle11. The cutouts27and37receive the upright portions53to allow smooth movement up and down of the major portion51relative to the protrusions23and33, i.e., of the hook55relative to the handle11.

The platforms42and43together form a floor of the space12of the handle11(FIG.1). The elongated recess41is located next to an edge of the platform42so that it becomes a slot19in the handle11. A space in the handle11is in communication with the space12through the slot19. A groove17is made in the shell13in vicinity of the platform42. Another groove17is made in the shell14in vicinity of the platform43. Thus, the space12is located between the grooves17.

Referring toFIG.8, the switch18includes a hook57, a bore58and rails59. The hook57extends from a front face of the switch18. The bore58is made in a lower face of the switch18. The rails59extend from two opposite sides of the switch18. The switch18is located in the space12, which is located above the platforms42and43. Each of the rails59is movable in and along a corresponding one of the grooves17to render the switch18smoothly movable front and rear ends of the space12. At the front end of the space12, the hook57is engaged with the hook55. The compression spring56allows the hook55to be pushed down by the hook57immediately before the hooks55and57are engaged with each other. The compression spring56lifts the hook55immediately after the hooks55and57are engaged with each other (FIG.12).

The shell13includes a chamber20. The shell14includes a chamber30. The chambers20and30together become the space in the handle11to receive a holder60(FIG.7). The shell13includes a mouth28in the front end. The shell14includes a mouth38in the front end. The mouths28and38become the open end15of the handle11(FIG.1). The shell13includes a notch29in a lower portion. The shell14includes a notch39in a lower portion. The notches29and39become an orifice via which the space in the handle11is in communication with the exterior of the handle11. A front end of the vertical facet45is in vicinity of the mouth38.

Referring toFIGS.7through12, the holder60includes a slat62, a carrier70and an elastic leaf80. The slat62includes a protuberance63extending from a side. A tensile spring61includes an end connected to the protuberance63and another end connected to a protuberance (not numbered) extending from the shell14. Thus, the tensile spring61tends to move the slat62toward the closed end16of the handle11(FIG.1). At an upper edge, the slat62includes a connector64inserted in the bore58through the slot19. Thus, the switch18is operable to move the slat62between a front position and a rear position.

The connector64is in contact with a rear end of the slot19to keep the switch18at the rear end of the space12against the tensile spring61. Now, the slat62is in the rear position to completely insert the blade47in the handle11.

The switch18is operable to move the slat62to the front position. The slat62is retained in the front position as the hook57of the switch18is engaged with the hook55of the button50. Thus, the slat62extends the front section of the blade47from the handle11through the open end15.

The carrier70is formed with a flat space71in an internal side and a shallow space75in an external side. The carrier70is connected to the slat62via fitting, a rivet or a screw so that they are moveable together. A long rib72and a short rib73are in contact with the slat62so that the flat space71is covered by the slat62. The flat space71receives the rear section of the blade47, which is inserted in the handle11via the open end15.

Preferably, the elastic leaf80is made of metal and shaped in compliance with the shallow space75. The elastic leaf80is formed with a cutout81at a rear end and an orifice82in vicinity of the cutout81. The cutout81receives a protrusive portion77formed on the carrier70and the orifice82receives a boss76formed on the carrier70to correctly locate the elastic leaf80in the shallow space75(FIG.9). A free end of the boss76is enlarged to keep the elastic leaf80in the shallow space75.

The elastic leaf80includes a lever83and a latch84, both perpendicularly extending from an upper end. The lever83extends longer than the latch84. The lever83is located higher than the latch84(FIG.14), The lever83extends above a recessed section74of an upper edge of the carrier70. The lever83shields a separating portion48formed between two cutouts49made in an upper edge of the blade47. The lever83is operable to move the latch84into or from a selected one of the cutouts49. A slant edge85of the latch84abuts against a front edge of the selected cutout49to bring the blade47into contact with the carrier70(FIG.10) to render the blade47movable with the carrier70.

The free end of the boss76is enlarged by heating and pressing or molding or any other proper means as long as the boss76becomes a rivet to keep the elastic leaf80in tight contact with the carrier70. Alternatively, the boss76can receive a screw formed with an enlarged head larger than the orifice82in diameter.

Referring toFIG.10, the holder60, which includes the slat62and the carrier70, is moved to the front position shown in phantom lines from the rear position shown in solid lines in a sense of direction indicated with an arrow head86. The front section of the blade47is extended from the handle11via the open end15.

Referring toFIGS.13and14, during the movement of the holder60to the front position, the carrier70travels toward the open end15of the handle11(FIG.11). The lever83slides on the slant facet46of the bump44of the shell14and finally reaches the vertical facet45of the bump44of the shell14. Thus, the lever83bends the elastic leaf80to move the latch84from any of the cutouts49of the blade47, which is partially inserted in the flat space71. That is, the slant edge85no longer restrains any edge of any of the cutouts49. This, the blade47is allowed to be moved from the handle11via the open end15. A rear section of a new blade47can be inserted in the handle11via the open end15.

Referring toFIGS.7,10,11and13, the button50is pressed to disengage the hook55from the hook57of the switch18to allow the tensile spring61to move the holder60rearward. Thus, the lever83moves from the vertical facet45of the bump44to the slant facet46of the same, and then to the shell14, thereby allowing the elastic leaf80to contact the carrier70and the latch84to extend into a selected one of the cutouts49. Now, the substitution of the new blade47for the used blade47is completed. The tensile spring61keeps the holder60in the rear position where the new blade47is completely inserted in the handle11.

Furthermore, even with the new blade47completely inserted in the handle11, the boxcutter10can be used to cut a string or strap. To this end, a section of the string or strap is inserted in to the handle11via the orifice that consists of the notches29and39.