Box cutter

Abstract

To provide a safe replaceable blade cutter knife which enables a blade to be replaced from the tip side and prevents the blade from being removed from a slide unit against user's will.SOLUTION: A cutter knife 1 includes: a holder 10 having a rail 12 in which a longitudinal opening is formed in a longitudinal direction; and a slide unit 20 which is connected to the blade 5 and slidably held by the rail 12. The rail 12 has: step parts 15 each of which is formed at the tip side, defines the tip side of a normal slide range of the slide unit 20, and narrows a lateral width of the longitudinal opening; and a blade replaceable recessed part 16 installed on a bottom surface located at the tip side relative to the step parts 15. The slide unit 20 has: a hook 35 having a long plate part 36 in which a blade connection protruding part 37 is installed at a tip; and a step collision part 43 which may move between a step collision position and a collision avoidance position when the slide unit 20 is in a normal slide forefront end.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a cutter knife with a replaceable blade. [Background technology]

[0002] 2. Description of the Related Art Conventionally, cutter knives have been provided that are slidable relative to a holder and have a folding, replaceable blade, and are disclosed in, for example, Patent Documents 1 to 3 listed below.

[0003] The cutter knives disclosed in Patent Documents 1 to 3 are configured such that the blade can be replaced from the tip side by sliding the slider (slide unit) toward the tip side to release the connection between the blade and the slider. Replacing the blade from the tip side is an easier task than sliding the slider toward the handle and replacing the blade from the rear end. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-195093 A [Patent Document 2] JP 2003-265873 A [Patent Document 3] Japanese Utility Model Application Publication No. 55-167364 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the cutter knives disclosed in the above Patent Documents 1 to 3, the blade can be removed from the slider and replaced by moving the slider to a tip within the normal sliding range of the slider for protruding and retracting the tip of the folding blade from the tip of the holder.

[0006] In other words, since the tip of the slider within the normal sliding range is the blade replacement position, even if the user does not intend to replace the blade, the slider may slide to the blade replacement position and the blade may come off. If the blade comes off without the user's intention, it may lead to an accident such as injury.

[0007] The present invention has been made in consideration of such problems, and aims to provide a safe cutter knife with a replaceable blade, where the blade can be replaced from the tip side, and the blade will not come off from the slide unit against the user's will. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a cutter knife in which the blade can be replaced from the tip side, the cutter knife comprising: a holder having a rail with a substantially C-shaped cross section perpendicular to the longitudinal direction and a longitudinal opening formed therein; and a slide unit connected to the blade and slidably held on the rail, the rail having a step portion formed at the tip portion that narrows the lateral width of the longitudinal opening and that defines the tip side of a normal sliding range of the slide unit, and a blade replacement recessed portion provided on a bottom surface further on the tip side of the step portion, the slide unit comprising a hook having a long plate portion protruding toward the tip side and a connecting protrusion portion that is inserted into a connecting hole of the blade provided on the tip upper surface of the long plate portion. and a step collision portion that is movable between a step collision position where the slide unit collides with the step portion when positioned at the tip of the normal slide and prevents the slide unit from sliding toward the tip, and a collision avoidance position where the slide unit retreats from the step collision position to avoid collision with the step portion and allows the slide unit to slide further toward the tip, and is characterized in that when the slide unit is positioned at the tip of the normal slide, when the step collision portion retreats to the collision avoidance position and the slide unit moves to a blade replacement position further toward the tip, the tip of the long plate portion descends in the blade replacement recess, causing the connecting protrusion to also descend and releasing the connection between the slide unit and the blade. Effect of the Invention

[0009] According to the cutter knife of the present invention, the blade will not come off from the slide unit unless the user intentionally moves it to the blade replacement position, and therefore the cutter knife is safe. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a plan view of a cutter knife according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a vertical sectional view of the cutter knife according to the first embodiment of the present invention. [Diagram 3]FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is an exploded perspective view of the cutter knife according to the first embodiment of the present invention. [Diagram 5] FIG. 5 is an exploded perspective view of the slide unit according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a plan view for explaining the blade replacement operation according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a vertical sectional view for explaining the blade replacement operation according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a plan view of a cutter knife according to a second embodiment of the present invention. [Figure 9] FIG. 9 is a vertical sectional view of a cutter knife according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view taken along line BB in FIG. [Figure 11] FIG. 11 is an exploded perspective view of a cutter knife according to the second embodiment of the present invention. [Figure 12] FIG. 12 is an exploded perspective view of a slide unit according to the second embodiment of the present invention. [Figure 13] FIG. 13 is a plan view for explaining the blade replacement operation according to the second embodiment of the present invention. [Figure 14] FIG. 14 is a vertical sectional view for explaining the blade replacement operation according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First embodiment Hereinafter, a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 7. Fig. 6 and Fig. 7 are diagrams for explaining the replacement work of the blade 5, Fig. 6(a) and Fig. 7(a) show the state when the normal slide is at the most extreme position, and Fig. 6(b) and Fig. 7(b) show the state when the blade is at the blade replacement position.

[0012] In the first embodiment, an auto-lock type folding blade cutter knife 1 in which the slide position is automatically fixed at a predetermined pitch will be described. The cutter knife 1 includes a blade 5, a holder 10, and a slide unit 20 that is slidably installed on the holder 10 together with the connected blade 5.

[0013] The blade 5 is a folding blade type, and a connection hole 5a is formed at the base for connection to the slide unit 20. The holder 10 includes a resin holder body 11, a stainless steel rail 12, and a cap 19 detachably attached to the rear end of the holder body 11.

[0014] The holder body 11 is a longitudinal member that is held by the user's hand, and holds a rail 12, which is also a longitudinal member, on the inside. The rail 12 is a member that holds the slide unit 20 on the inside so that it can slide in the longitudinal direction, and its cross-sectional shape perpendicular to the longitudinal direction is approximately a square bracket (C-shape, U-shape).

[0015] At the longitudinal opening portion extending in the longitudinal direction of the rail 12, longitudinal opening folded-back portions 13 are formed on both the left and right sides along the longitudinal direction, folded back inward to hold the slide unit 20 slidably. The longitudinal opening folded-back portions 13 are provided with slide recesses 14 on both sides along the longitudinal direction, on which a number of recesses 14a are formed at predetermined intervals. The slide recesses 14 are used to temporarily fix the slide position of the slide unit 20 in an auto-locking manner.

[0016] At the tip side of the slide recess 14 of the rail 12, a step portion 15 is provided in the longitudinal opening folded back portion 13, which is a step that collides with the slide unit 20 moving in the tip direction and prevents the slide unit 20 from moving in the tip direction. The step portions 15 are provided on both the left and right side of the longitudinal opening folded back portion 13, respectively, and are formed to protrude inward so as to narrow the lateral width of the longitudinal opening.

[0017] This step 15 defines the leading end of the normal sliding range of the slide unit 20 for projecting and retracting the leading end of the folding blade 5 from the leading end of the holder 10. The rear end of the normal sliding range on the hand side is defined by a cap 19, and the slide unit 20 sliding toward the rear end side hits the cap 19 and stops.

[0018] A blade replacement recess 16 is provided on the bottom surface of the rail 12 further to the tip side of the step portion 15. In the blade replacement recess 16, the bottom surface of the rail 12 is one step lower than the other portions. Note that the blade replacement recess 16 is configured by recessing the bottom surface of the rail 12 into a rectangular parallelepiped shape, but the blade replacement recess 16 may have any configuration that allows the tip underside claw 38 of the hook 35 described below to descend, and may be an opening. In this specification, the blade replacement recess includes the blade replacement opening.

[0019] 5, the slide unit 20 includes, in order from above, a slide knob 25, a lock lever 40, a slider main body 21, a spring 30, and a hook 35. The slider main body 21 is an approximately rectangular plate overall, and is provided with a rectangular parallelepiped angular tube protrusion 22 that protrudes upward in the center. The inside of the angular tube protrusion 22 constitutes a spring storage section 23 in which the spring 30 is stored.

[0020] A lock lever connecting recess 24 for connecting the lock lever 40 is formed on the rear end side of the square tube protrusion 22 of the slider body 21. In addition, a spring horizontal bar exposure opening 22a is formed on both sides in the width direction of the square tube protrusion 22, through which a horizontal bar portion 31 (described later) of the spring 30 installed inside is exposed on the upper surface side. A blade connecting protrusion hole 21b is formed on the tip end of the slider body 21, through which a blade connecting protrusion 37 (described later) passes.

[0021] The slide knob 25 is a hollow rectangular parallelepiped member with an open bottom that is placed so as to cover the upper part of the square tube protrusion 22 of the slider body 21, and is connected to the slider body 21 so as to be able to slide a small distance in the longitudinal direction back and forth. The slide knob 25 is locked by a claw (not shown) so that it does not easily come off the square tube protrusion 22.

[0022] A spring depressing recess 26 is provided in the center of the lower inside of the main body of the slide knob 25. The spring depressing recess 26 is generally U-shaped with a downward concave shape in a vertical cross section parallel to the longitudinal direction, and when the slide knob 25 slides back and forth, the front and rear lower ends of the spring depressing recess 26 come into contact with the spring 30 and depress the spring 30 downward.

[0023] A square knob opening 27 is provided on the upper surface of the tip side of the slide knob 25, and a knob 44 of a lock lever 40 (described later) passes through the knob opening 27 and protrudes upward.

[0024] The spring 30 has a cross bar portion 31 extending horizontally in a direction perpendicular to the longitudinal direction, and a leaf spring portion 32 which protrudes diagonally downward from the cross bar portion 31 on both the tip (blade tip) side and the rear end (handle) side before assembly.

[0025] The hook 35 includes a long plate portion 36 extending in the longitudinal direction, a blade connecting protrusion 37 provided on the upper surface of the tip of the long plate portion 36, and a tip underside claw 38 formed on the underside of the tip of the long plate portion 36. The hook 35 sandwiches the spring 30 stored in the spring storing portion 23, and its base end is connected and fixed to the slider body 21 from below.

[0026] The blade connecting protrusion 37 is inserted into the connecting hole 5a of the blade 5, thereby connecting the blade 5 to the slide unit 20 so that they can slide together. The long plate portion 36 is constantly pressed downward by the elastic force of the leaf spring portion 32 of the spring 30, which functions as a second elastic portion and with which the upper surface of the long plate portion 36 comes into contact.

[0027] The lock lever 40 is a member for switching between preventing and allowing the sliding of the slide unit 20 to the blade 5 replacement position, which is further forward than the normal sliding range. The lock lever 40 has a generally rectangular frame shape and includes a frame portion 41, a slider body connecting protrusion 42, a step collision portion 43, and a knob 44.

[0028] The slider body connecting protrusion 42 is located on the proximal side of the frame portion 41 and protrudes downward. When assembling the slide unit, it is inserted into the lock lever connecting recess 24 of the slider body 21, and the slider body 21 and the lock lever 40 are connected and fixed together.

[0029] The lock lever 40 is disposed between the slide knob 25 and the slider body 21 , and is assembled so that the frame portion 41 surrounds the upper edge portion of the rectangular tube protrusion 22 of the slider body 21 .

[0030] The step collision portion 43 and the knob 44 are located at the tip side of the frame portion 41, and when an operator presses the knob 44 located at the top with a finger or the like, the knob 44 and the step collision portion 43 located below it move downward together, and when the finger or the like is released, the elastic force of the frame portion 41, which functions as a first elastic portion, causes the step collision portion 43 and the knob 44 to rise to their original positions.

[0031] The step collision portion 43 restricts the slide unit 20 from moving further toward the tip at the step collision position where the slide unit 20 collides with the step portion 15 of the rail 12 when the slide unit 20 is positioned at the very end of the normal sliding range (see Figures 6(a) and 7(a)).

[0032] At this time, when the knob 44 is pressed down to move the step collision portion 43 downwardly below the longitudinal opening fold-back portion 13 of the rail 12, it enters a collision avoidance position, the collision between the step collision portion 43 and the step portion 15 is resolved, and the slide unit 20 becomes able to move to a blade replacement position that is further forward than the normal slide tip position.

[0033] The above has explained the configuration of each component that makes up the slide unit 20. When the slide unit 20 is assembled, the spring 30 stored in the spring storage section 23 of the slider body 21 is pressed by the long plate portion 36 of the hook 35 located on the lower side so that the front and rear leaf spring portions 32 are horizontally positioned against the ceiling surface of the spring storage section 23.

[0034] Therefore, the horizontal bar portion 31 of the spring 30, both ends of which are exposed from the spring horizontal bar exposure openings 22a formed on both sides of the square tube protrusion portion 22 of the slider body 21, is always biased upward by the elastic force of the leaf spring portion 32 in the assembled state.

[0035] During normal sliding of the slide unit 20 relative to the holder 10 when the cutter knife 1 is in use, both ends of the horizontal bar portion 31 exposed from the spring horizontal bar exposure opening 22a fit into the respective recesses 14a of the slide recess 14 of the rail 12, thereby restricting the sliding and automatically fixing the sliding position of the slide unit 20.

[0036] When it is desired to release the position fixed during normal sliding and slide again, the slide knob 25 is pushed with a finger toward the tip or base, which is the direction in which the slider is to be slid. The slide knob 25 pushed with the finger moves a small distance relative to the slider body 21, causing the spring depression recess 26 to come into contact with the horizontal bar portion 31 of the spring 30 and move the horizontal bar portion 31 downward against the elastic force of the leaf spring portion 32.

[0037] When the horizontal bar portion 31 moves downward, it comes out of the recessed portion 14a of the rail 12, allowing the slide unit 20 to slide. When the slide unit 20 slides to the desired slide position and the user stops pressing the slide knob 25 with a finger, the slide knob 25 returns to its original position relative to the slide main body 21, and the horizontal bar portion 31 of the spring 30 is no longer pressed downward, so that the horizontal bar portion 31, which is biased upward, rises.

[0038] As a result, the cross bar 31 again fits into the recess 14a of the rail 12, the sliding stops, and the sliding position of the slide unit 20 is fixed at the desired position again. If the slide unit 20 continues to move toward the tip, as described above, the step collision part 43 of the lock lever 40 collides with the step part 15 installed near the tip of the rail 12, and the slide unit 20 cannot be moved any further toward the tip (normally the most extreme slide position).

[0039] Next, a description will be given of the work required for replacing the blade 5. When replacing the blade 5, it is usually necessary to move the slide unit 20 from the most distal position of the slide to a blade replacement position further to the distal end.

[0040] In order to move the normal slide further from its most distal end position, as described above, it is necessary to move the step collision portion 43 away from the step collision position to the collision avoidance position to release the collision between the step collision portion 43 of the lock lever 40 and the step portion 15 of the rail 12. When the knob 44 of the lock lever 40 is pressed down, the lower step collision portion 43 formed integrally therewith also moves down.

[0041] When the step collision portion 43 descends below the longitudinal opening fold portion 13 where the step portion 15 is formed and the collision between the two is released, the slide unit 20 becomes capable of moving further toward the tip from the normal slide tip position, so that when the slide knob 25 is pushed toward the tip with a finger, the slide unit 20 moves further toward the tip.

[0042] When the slide unit 20 moves further toward the tip side than the most extreme position of the normal sliding range, the tip of the slider body 21 hits the tip stopper 17 of the rail 12, so that the slide unit 20 stops at the blade replacement position and cannot move further toward the tip side.

[0043] 6(b) and 7(b), when the slide unit 20 moves to the blade replacement position, the tip underside claw 38 at the tip of the hook 35 reaches the position of the blade replacement recess 16. Since the upper surface of the long plate portion 36 of the hook 35 is in contact with the leaf spring portion 32 of the spring 30, when the tip underside claw 38 reaches the blade replacement recess 16 and the lower portion is released, the tip underside claw 38 is pushed downward by the elastic force of the leaf spring portion 32 functioning as the second elastic portion and descends into the blade replacement recess 16.

[0044] When the tip of the long plate portion 36 of the hook 35 descends, the blade connecting protrusion 37 also descends and comes out of the connecting hole 5a of the blade 5. This releases the connection between the blade 5 and the slide unit 20, and the blade 5 can be pulled out from the tip side.

[0045] Next, a new blade 5 is attached. The new blade 5 is inserted from the tip end side of the rail 12 with the connecting hole 5a side facing up until the connecting hole 5a is positioned above the blade connecting protrusion 37 of the hook 35.

[0046] The slider body 21 has a blade end abutment 21a, which is a step that collides with the proximal end of the blade 5 to position it, on its upper surface at the tip side, and is configured so that when the tip of the blade 5 is caused to collide with the blade end abutment 21a, the connecting hole 5a is positioned above the blade connecting protrusion 37.

[0047] When the blade 5 is further pushed toward the hand side while the connecting hole 5a of the blade 5 is positioned above the blade connecting protrusion 37, the blade 5 and the slide unit 20 slide toward the hand side, and the tip underside claw 38 comes out of the blade replacement recess 16 and rises.

[0048] That is, the blade connecting protrusion 37 also rises and is inserted into the connecting hole 5a, and the new blade 5 is connected to the slide unit 20. If the blade 5 is held and continued to be pushed toward the hand, the slide unit 20 advances to the most extreme normal slide position and returns to the normal slide range.

[0049] As described above, according to the first embodiment, when replacing the blade 5 from the tip side, simply moving the slide unit 20 to the tip side does not release the connection between the blade 5 and the slide unit 20. Instead, the user can operate the lock lever 40 to intentionally move the step collision portion 43 from the step collision position to the collision avoidance position, thereby enabling replacement of the blade 5, thus ensuring safety.

[0050] Although the first embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0051] For example, the shape, size, material, etc. of the members constituting the cutter knife can be appropriately changed. Furthermore, the members constituting the holder and the slide unit can be formed integrally or separated into separate members as appropriate.

[0052] In addition, in the above first embodiment, the spring that functions for the auto-lock functions as a second elastic part for pushing the tip of the hook downward, but without using the spring for both purposes, for example, the tip may be configured to be urged downward by the elastic force of the long plate part of the hook.

[0053] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Figures 8 to 14. Figures 13 and 14 are diagrams for explaining the replacement work of the blade 5, with Figures 13(a) and 14(a) showing the state when the normal slide is at the most distal position, and Figures 13(b) and 14(b) showing the state when the blade is at the blade replacement position.

[0054] In the second embodiment, a screw-type folding blade cutter knife 2 in which the sliding position is fixed by a thumb screw will be described. In this embodiment, the differences from the first embodiment will be mainly described, and the same component names will be used for the common configurations, and the description will be omitted.

[0055] The cutter knife 2 includes a blade 5, a holder 60, and a slide unit 70. The holder 60 includes a holder body 61 and a rail 62. The rail 62 is formed with a longitudinal opening folded-back portion 63 that is folded back to hold the slide unit 70 in the longitudinal direction.

[0056] In the longitudinal opening portion extending in the longitudinal direction of the rail 62, which has a cross-sectional shape that is approximately bracket-shaped (C-shaped, U-shaped), longitudinal opening fold-back portions 63 are formed on both the left and right sides along the longitudinal direction, which are folded inward to hold the slide unit 70 in a freely slidable manner.

[0057] A first step 65a, which is a step that collides with the slide unit 70 moving in the tip direction and prevents the slide unit 70 from moving in the tip direction, is provided in the longitudinal opening folded-back portion 63 on the tip side of the rail 62. Unlike the first embodiment described above, the first step 65a is formed only in the longitudinal opening folded-back portion 63 on one side (the upper side in FIG. 8), and is formed to protrude inward so as to narrow the lateral width of the longitudinal opening.

[0058] This first step portion 65a defines the tip of the normal sliding range of the slide unit 70. A step recess 65b is provided in the longitudinal opening folded-back portion 63 on the opposite side (lower side in FIG. 8) of the first step portion 65a, and is formed from the middle of the rail 62 to a little toward the tip side of the first step portion 65a, and the step recess 65b is formed recessed outward so as to widen the lateral width of the longitudinal opening.

[0059] The step protruding inward on the tip side of the stepped recess 65b is a second stepped portion 65c, and the second stepped portion 65c functions as a tip stopper that prevents the slide unit 70 from moving toward the tip side when the slide unit 70 moves toward the tip side beyond the normal sliding range. Also, the step protruding inward on the rear end side of the stepped recess 65b is a third stepped portion 65d. A blade replacement recess 66 is provided on the bottom surface of the tip side of the stepped recess 65b of the rail 62.

[0060] 12, the slide unit 70 includes, in order from above, a dial knob 75, a slider main body 71, a spring 80, and a hook 85. The slider main body 71 is an approximately rectangular plate overall, and is formed with a rectangular prism-shaped protrusion 72 that protrudes upward from the center toward the rear end.

[0061] The width of the prismatic protrusion 72 in the lateral direction perpendicular to the longitudinal direction is slightly shorter than the width of the longitudinal opening of the rail 62. When the slider body 71 is slidably held on the rail 62, only the prismatic protrusion 72 protrudes outward from the longitudinal opening of the rail 62. In addition, the right end (upper side in FIG. 8) of the prismatic protrusion 72 facing the tip side is a first step collision part 72a that normally collides with the first step part 65a at the most forward sliding position.

[0062] The slider body 71 is provided with a lateral elastic spring portion 74, which is a rod-shaped member that extends substantially in the longitudinal direction on one side surface on the left side facing the tip side and protrudes outward to the side. Two lateral elastic spring portions 74 are provided: one protruding forward from the side surface of the slider body 71, and the other protruding rearward.

[0063] When the slide unit 70 is slidably installed on the rail 62, the side elastic spring portion 74 comes into contact with the inner surface on the left side of the rail 62 and is pushed back from the protruding position toward the slider main body 71. Therefore, the slider main body 71 held within the rail 62 is constantly pushed to the right side, opposite the side on which the side elastic spring portion 74 is installed, by the elastic force of the side elastic spring portion 74 functioning as the first elastic portion.

[0064] As a result, even if the size of the rail 62 is slightly larger than the size of the slider body 71 and there is play in the width direction of the slider body 71 installed within the rail 62, the slider body 71 is pushed to one side by the lateral elastic spring portion 74, so that it can slide stably against the rail 62.

[0065] Here, the overall longitudinal length of the rectangular columnar convex portion 72 of the slider body 71 is approximately the same as, and slightly shorter than, the length from the third step portion 65d to the first step portion 65a (the length of the step recess 65b) in the longitudinal direction of the rail 62 described above.

[0066] When the slide unit 70 is positioned other than at the normal slide tip, both lateral sides of the rectangular convex portion 72 of the slider body 71 are sandwiched between the longitudinal opening folds 63 on both sides of the rail 62, and it is not possible to move in the width direction. However, when the slide unit 70 is positioned at the normal slide tip position, the entire rectangular convex portion 72 is positioned next to the step recess 65b, and it is possible to move the rectangular convex portion 72 toward the step recess 65b (to the left when facing the tip) against the elastic force of the lateral elastic spring portion 74.

[0067] When the prismatic convex portion 72 fits into the step recess 65b, collision between the first step collision portion 72a of the prismatic convex portion 72 and the first step portion 65a is avoided, and it is possible to move the prismatic convex portion 72, which is exposed to the outside from the longitudinal opening of the rail 62, further toward the tip side.

[0068] When the slide unit 70 moves further toward the tip than the normal slide extreme position, the left tip (lower side in Figure 8) of the rectangular prism protrusion 72 collides with the second step portion 65c on the tip side of the step recess 65b and stops, this position becoming the blade replacement position, and the left tip of this rectangular prism protrusion 72 becomes the second step collision portion 72c.

[0069] The dial knob 75 includes a male screw 75a and a click spring 76. A female screw 72b into which the male screw 75a is screwed is formed on the upper surface of the rectangular column protrusion 72 of the slider body 71, and the dial knob 75 is connected to the slider body 71 by screwing via the click spring 76.

[0070] The tip of the male screw 75a of the dial knob 75 protrudes toward the bottom side of the slide unit 70, and the sliding position of the slide unit 70 is fixed at the desired position when the tip of the male screw 75a that is screwed in comes into contact with the bottom surface of the rail 62.

[0071] The spring 80 is sandwiched between the upper slider body 71 and the lower hook 85, and one end of the spring 80 is connected to a spring connection recess (not shown) formed on the lower surface of the slider body 71. The spring 80 is a return spring, and urges the tip side of the hook 85, which comes into contact with its lower surface, downward with its elastic force.

[0072] The hook 85 includes a long plate portion 86 extending in the longitudinal direction, a blade connecting protrusion 87 provided on the upper surface of the tip of the long plate portion 86, and a tip underside claw 88 formed on the underside of the tip of the long plate portion 86. The hook 85 has a base end portion connected and fixed to the slider body 71 from below, sandwiching the spring 80 therebetween.

[0073] The configuration of the slide unit 70 has been described above, and next, a description will be given of the work performed when replacing the blade 5. In performing this work, first, the slide unit 70 is slid to the leading end of the normal sliding range.

[0074] 13(a) and 14(a), when the slide unit 70 moves to the normal slide tip position, the first step collision portion 72a of the rectangular column protrusion 72 collides with the first step portion 65a of the rail 62 and stops (step collision position). In order to move it further to the tip side, the slider body 71 is moved laterally to the opposite side to the first step portion 65a by the operator's finger or the like against the elastic force of the lateral elastic spring portion 74.

[0075] When the rectangular columnar protrusion 72 fits into the stepped recess 65b, it is in the collision avoidance position, and collision between the first stepped collision portion 72a and the first stepped portion 65a is avoided. In the collision avoidance position, the rectangular columnar protrusion 72 is slidable toward the tip end, so that when the rectangular columnar protrusion 72 is pushed toward the tip end with a finger, the slide unit 70 moves further toward the tip end.

[0076] When the slide unit 70 moves further toward the tip than the most extreme position of the normal sliding range, the second step collision portion 72c of the left tip corner facing the tip side of the rectangular column convex portion 72 collides with the second step portion 65c on the left side of the rail 62, causing the slide unit 70 to stop at the blade replacement position and to be unable to move any further toward the tip.

[0077] 13(b) and 14(b), when the slide unit 70 moves to the blade replacement position, the tip underside claw 88 at the tip of the hook 85 reaches the position of the blade replacement recess 66. Since the upper surface of the long plate portion 86 of the hook 85 is in contact with the spring 80 functioning as the second elastic portion and is biased downward, when the tip underside claw 88 reaches the blade replacement recess 66 and the lower side is released, the tip underside claw 88 is pushed downward and descends into the blade replacement recess 66.

[0078] When the tip of the long plate portion 86 of the hook 85 descends, the blade connecting protrusion 87 also descends and comes out of the connecting hole 5a of the blade 5. This releases the connection between the blade 5 and the slide unit 70, and the blade 5 can be pulled out from the tip side.

[0079] After replacing the blade 5 with a new one, the slide unit 70 is pushed toward the rear end to slide it. When the rear end side of the prismatic protrusion 72 returns to a position where it contacts the third step portion 65d, which is the rear end of the stepped recess 65b, the first step collision portion 72a of the prismatic protrusion 72 also returns to the position of the first step portion 65a in the longitudinal direction.

[0080] As a result, the slider body 71, which is constantly biased by the lateral elastic spring portion 74 toward the first step portion 65a on the right side facing the tip side, moves to the right, exits the left step recess 65b, and returns to its normal slide tip position.

[0081] The above describes the second embodiment. According to this embodiment, the same action and effect as the first embodiment is achieved, and in the second embodiment, the step collision portion is configured to be movable between the step collision position and the collision avoidance position by moving it horizontally in the lateral direction, thereby making it possible to realize a slide unit 70 with a simple structure and a small number of parts.

[0082] The second embodiment of the present invention has been described above, but various modifications are possible in this embodiment as in the first embodiment. In addition, in the second embodiment, a spring is provided to urge the tip of the hook downward, but the tip may be configured to be urged downward by the elastic force of the long plate portion of the hook. [Explanation of symbols]

[0083] 1. Box cutter 10 Holder 11 Holder body 12 Rail 13 Longitudinal opening folded part 14 Slide recess 14a Recess 15 Step 16 Blade replacement recess 17 Tip stopper 19 Cap 20 Slide unit 21 Slider body 21a Blade end stop 21b Hole for blade connecting protrusion 22 Square tube protrusion 22a Spring bar exposure opening 23 Spring storage section 24 Lock lever connection recess 25 Slide knob 26 Spring depression recess 27 Knob opening 30 Spring 31 Horizontal bar 32 Leaf spring part 35 Hook 36 Long board section 37 Blade connecting protrusion 38 Lower tip claw 40 Lock lever 41 Frame section 42 Slider body connecting protrusion 43 Step collision area 44 Knob 2. Box cutter 60 Holder 61 Holder body 62 Rail 63 Longitudinal opening folded part 65a First step part 65b Step recess 65c Second step part 65d Third step 66 Blade replacement recess 70 Slide unit 71 Slider body 72 Square pillar protrusion 72a First step collision part 72b female thread 72c Second step collision part 74 Lateral elastic spring part 75 Dial knob 75a male thread 76 Click Spring 80 Spring 85 Hook 86 Long board section 87 Blade connecting protrusion 88 Lower tip claw 5 Blades 5a connection hole

Claims

1. In a cutter knife where the blade can be replaced from the tip side, A holder having a rail whose cross section perpendicular to the longitudinal direction is substantially C-shaped and in which a longitudinal opening is formed in the longitudinal direction; a slide unit connected to the blade and slidably held on the rail, The rail is a step portion formed on the tip side to define the tip side of a normal sliding range of the slide unit and narrowing the lateral width of the longitudinal opening; a blade replacement recess provided on a bottom surface of the step portion on the tip side thereof; having The slide unit is a hook having a long plate portion protruding toward the tip end and a blade connecting protrusion that is inserted into a connecting hole of the blade provided on an upper surface of the tip end of the long plate portion; a step collision portion that is movable between a step collision position where the slide unit collides with the step portion when the slide unit is normally located at the front end of the slide and prevents the slide unit from sliding toward the front end, and a collision avoidance position where the slide unit moves away from the step collision position to avoid collision with the step portion and to allow the slide unit to slide further toward the front end; having This cutter knife is characterized in that, when the slide unit is positioned at the very tip of the normal slide, the step collision portion retreats to the collision avoidance position and the slide unit moves further to the blade replacement position at the tip side, the tip of the long plate portion descends in the blade replacement recess, causing the connecting protrusion to also descend and releasing the connection between the slide unit and the blade.

2. 2. The cutter knife according to claim 1, wherein the slide unit includes a first elastic portion that, at the normal slide tip position, pushes the step collision portion toward the step collision position by an elastic force.

3. 3. The cutter knife according to claim 1, wherein the slide unit further comprises a second elastic portion that, when in the blade replacement position, pushes the tip of the hook downward by elastic force.

4. The rail has a longitudinal opening folded portion formed on both the left and right sides of the longitudinal opening facing the tip side, the step portion is formed only on the longitudinal opening folded portion on one side so as to protrude inward, and the longitudinal opening folded portion on the other side opposite to the step portion has a step recess formed therein that is recessed outward so as to widen the lateral width of the longitudinal opening, 4. The cutter knife according to claim 1, wherein the slide unit is configured to be movable laterally toward the stepped recess at the leading end of the normal slide.

5. 5. The cutter knife according to claim 4, wherein the length in the longitudinal direction of the stepped recess is slightly longer than the length in the longitudinal direction of the protruding portion exposed to the outside through the longitudinal opening of the slide unit.

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