Utility Knife With Replaceable Blade

Abstract

The present invention first provides a utility knife with a replaceable blade, comprising a knife handle, a blade holder, a blade and a locking device that locks the blade in the blade holder. The blade holder and the blade are enabled to switch between a first position and a second position. When the blade holder and the blade are in the first position, the blade is used for cutting operation, and when the blade holder and the blade are in the second position, both the blade holder and the blade are received in the knife handle. The utility knife further includes a restriction means which is thus arranged as, when the blade holder is in the second position and the locking device is in unlocked state, the restriction means is used for preventing the detachment of the blade from the blade holder by confining the movement of the blade relative to the blade holder. The present invention also provides a folding utility knife with a replaceable blade and a retractable utility knife with a replaceable blade, and a utility knife with multiple tools and replaceable blades.

Claims

1. A folding utility knife with a replaceable blade, comprising a knife handle, a blade holder, a blade and a locking device that locks the blade in the blade holder, the blade holder and the blade are enabled to be folded and received in the knife handle or to extend out from the knife handle, characterized in that the utility knife further includes a restriction means which is thus arranged that, when the blade holder and the blade are folded and received in the knife handle and the locking device is in unlocked state, the restriction means is used for preventing the detachment of the blade from the blade holder by restricting the movement of the blade relative to the blade holder; wherein the restriction means is a projection blocking the blade from detachment thereof from the blade holder; the folding utility knife with a replaceable blade has a side-lock structure comprising a deflection leaf spring arranged inside the knife handle; wherein the projection extends out from a side of the deflection leaf spring arranged inside the knife handle.

2. The folding utility knife with a replaceable blade as claimed in claim 1, wherein the projection is formed by bending a part of the deflection leaf spring.

3. A utility knife with a replaceable blade, comprising a knife handle and multiple tools, the tools are enabled to be received in the knife handle respectively via folding or sliding or to extend out from the knife handle, at least one of the tools includes a blade holder, a blade and a locking device that locks the blade in the blade holder, characterized in that the utility knife further includes a restriction means which is thus arranged that, when the blade holder and the blade are received in the knife handle and the locking device is in an unlocked state, the restriction means is used for preventing the detachment of the blade from the blade holder by restricting the movement of the blade relative to the blade holder; wherein the blade holder is folded and received in the knife handle or to extend out from the knife handle via folding, and the restriction means is a projection blocking the blade from detachment thereof from the blade holder; wherein the utility knife with a replaceable blade has a side-lock structure comprising a deflection leaf spring arranged inside the knife handle; wherein the projection extends out from a side of the deflection leaf spring arranged inside the knife handle.

4. The utility knife with a replaceable blade as claimed in claim 3, wherein the projection is formed by bending a part of the deflection leaf spring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] FIG. 1 shows a locking device of the prior art, where the locking device is in a locked state.

[0061] FIG. 2 is the locking device as shown in FIG. 1 in an unlocked state.

[0062] FIG. 3 is a top view of another locking device in the prior art where the locking device is in locked state.

[0063] FIG. 4 is a front view of the locking device as shown in FIG. 3.

[0064] FIG. 5 is a top view of the locking device as shown in FIG. 3 where the locking device is in an unlocked state.

[0065] FIG. 6 shows a locking device as shown in FIG. 3 where the blade is partially detached from the blade holder.

[0066] FIG. 7 shows a perspective view of the detachment of the blade from the knife.

[0067] FIG. 8 shows a front view of a folding utility knife with a replaceable blade embodying the present invention.

[0068] FIG. 9 shows a front view of another folding utility knife with a replaceable blade embodying the present invention

[0069] FIG. 10 shows a front view of a folding utility knife with a replaceable blade having a back-lock structure embodying the present invention.

[0070] FIG. 11 shows a front view of a folding utility knife with replaceable blades having side-lock structures.

[0071] FIG. 12 is the top view of FIG. 11.

[0072] FIG. 13 shows a front view of a folding utility knife with a replaceable blade with a side-lock structure as implemented in FIG. 11 and FIG. 12 embodying the present invention.

[0073] FIG. 14 shows a top view of another folding utility knife with a replaceable blade with a side-lock structure as implemented in FIG. 11 and FIG. 12 embodying the present invention.

[0074] FIG. 15 shows a front view of a further embodiment of the utility knife with a replaceable blade of the present invention.

[0075] FIG. 16 is a cross-sectional view of the embodiment as shown in FIG. 15 in A-A direction.

[0076] FIG. 17 is an enlarged view of part B as shown in FIG. 16.

[0077] FIG. 18 is a front view of an embodiment of the retractable utility knife with a replaceable knife of the present invention, where the locking device is in a locked state.

[0078] FIG. 19 is a front view of the embodiment as shown in FIG. 18 in unlocked state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] As mentioned before, the present invention aims to provide a safety utility knife with replaceable blade, which is achieved by adding a restriction means to prior utility knives with replaceable blade, where the restriction means is thus arranged that, when the blade is received into the knife handle and the locking device is in an unlocked state, the restriction means is used for preventing the detachment of the blade from the blade holder.

[0080] In an embodiment of the present invention as shown in FIG. 8, 100 is a folding utility knife with a replaceable blade where the restriction means is a projection 106a extending from an inner side of the knife handle 109. And the blade 105 is fixed on the blade holder 107 by a locking device; when the blade holder is folded and received into the knife handle 109, the end 1051 of the knife 105 is adjacent to the projection 106a. When the switching member 101 is unintentionally touched upon, resulting in unlocked state of the locking device, the blade 105 is arranged to be blocked via the engagement of the end 1051 and the projection 106a when the blade 105 slightly slides outward from the blade holder 107, thus the detachment of the blade 105 from the blade holder 107 is prevented.

[0081] In that case, the restriction means can be an independent member 106a fixedly connected to an inner side of the knife handle as shown in FIG. 8, and can also be, as shown in FIG. 9, a 106b integrally modeled with the knife handle. Furthermore, 106b can also be assembled afterwards.

[0082] Similarly, for the folding utility knife having a back-lock structure as shown in FIG. 10, the latch 114 as shown in the figure, under the effect of the spring 115, is locked in the notch 116 arranged at the end part of the blade holder 107, and the restriction means is a projection 106e arranged on an inner side of the knife handle. The projection 106e can also be an independent member mounted on an inner side of the knife handle, and be integrally modeled with the knife handle, or be assembled afterwards.

[0083] For the folding utility knife with replaceable blades having a side-lock structure as shown in FIG. 11, where a deflection leaf spring 108 used for locking is arranged in the knife handle as shown in FIG. 12. In that case, the restriction device can also be a projection 106c extending from the side of the deflection leaf spring 108 as shown in FIG. 13, or a 106d which is formed by bending a part of the deflection leaf spring 108, as shown in FIG. 14.

[0084] In order to prevent the blade from falling off the knife, the space between the projection and the blade is thus configured so that, when the end of the blade engages with the projection, at least a part of the blade is retained in the blade holder so as to prevent full detachment of the blade from the blade holder.

[0085] However, if the projection is arranged to be too far from the blade, then when the blade reaches the projection, part of the blade already slides out of the blade holder, thus the detached blade is probably tilting in downward direction, i.e. the direction that the knife edge faces. Thus, the tilted blade, on one hand, may partially be exposed out of the knife handle, and on the other hand, the tilted blade may also be stuck between the projection and the locking member, being unable to move. A solution to the problem is to arrange the projection to be very close to the end of the blade, so that a slight movement of the blade will have the blade be blocked by the projection, thus the blade is unable to tilt. Another solution is that in addition to the projection having a portion disposed in the direction of the blade detachment from the blade holder, a portion of the projection is arranged beneath the detached blade in the direction that the blade edge faces, as the 1061a shown in FIG. 8 or the 1061b shown in FIG. 9. Besides, two projections can be simultaneously arranged, one of which is disposed in the sliding direction of the blade from the blade holder, and the other of which is disposed beneath the detached blade, so that the movements of the blade in these two directions are restricted at the same time to prevent full detachment of the blade and the downward tilting of the partially detached blade which causes a part of the blade protruding out of the knife handle.

[0086] It should be pointed out that, some of the prior folding utility knives arrange connection pin axles to both ends of the knife handle in order to connect the two pieces of handle bodies, but as known from the foregoing description, to prevent the detachment of the blade, the projection needs to be specifically arranged, and since the pin axle of the knife handle or other similar parts of the prior folding utility knife are not intentionally arranged for the purpose, thus all of them are incapable of preventing, or at least, incapable of reliably preventing the detachment of the blade.

[0087] According to an alternative embodiment of the present invention as shown in FIG. 15, the restriction means is a protective cover 110 sheathing the blade 105, the protective cover 110 is provided with a button-hole part 111, and a button 112 is arranged on the blade holder 107. The protective cover 110 is mounted to the blade holder 107 through the connection of the button-hole part 111 and button 112. The blade 105 is retained in the protective cover 110. In order to easily connect the button-hole part 111 to the button 112, the button-hole part 111 is connected with a flexible part 113 of the prior art which is widely used in connecting plastic objects providing not only reliable connection therebetween but also favorable flexible performance, as shown in FIG. 16 and FIG. 17. Thus, when the blade 105 is received in the knife handle, even if the locking device is in an unlocked state, the blade 105 is incapable of detaching from the blade holder as long as the protective cover is present. Before using the knife, the button-hole part 111 should be released from the button 112 and then the protective cover 110 is removed from the blade 105; after using, the protective cover 110 is mounted back to sheathe the blade 105 which is received in the handle. It is understood that other detachable mounting method of the prior art may also be used for mounting the protective cover to the utility knife, such as snap button or sticky mat, etc. Although FIGS. 15 to 17 show common folding utility knives with replaceable blade, it is understood that, this restriction means in protective cover method is also adaptable to folding utility knives with replaceable blade having a back-lock or a side-lock mechanism.

[0088] FIG. 18 and FIG. 19 show an embodiment of implementing the protective cover 110 to a retractable utility knife with replaceable blades, where the blade 105 and the protective cover 110 are capable to be received in the knife handle. Similarly, restricted by the protective cover 110, even if the locking device is in an unlocked state, the blade 105 can not detach from the knife as long as the protection 110 is present, as shown in FIG. 18.

[0089] Besides, it can be understood by technicians of this field that, the present invention can be alternatively implemented to the utility knives with multiple tools such as shown in FIG. 11 and FIG. 12 (in FIG. 11 and FIG. 12, two blades are respectively disposed at both ends of the knife handle). Therefore, it doesn't matter that, what kind of working parts each tool is, whether the tools are arranged on one end or both ends of the utility knife, and whether the tools are or received in the knife handle in a folding or sliding way, as long as one tool of the utility knife has an aforementioned replaceable blade, the problem that the present invention aims to solve resides therein, and the restriction means of the present invention can then be implemented to eliminate the induced safety hazard of possible detachment of the blade.

[0090] The foregoing description details the preferred embodiments of the invention. It should be understood that with the general technique of this field, no inventive work is necessary as to make multiple amendments and changes according to conception of this invention. Therefore, all the technical schemes gained from logical analysis, deductions or limited experimentation based on the conception of the present invention by technicians in this field, should be considered within the protection range asserted in the Claims.