Utility knife

Abstract

A utility knife has a housing, a blade holder movable between a front position and a rear position in the housing, and first and second return formations of which one is mounted on the housing and the other on the blade holder. The first and second return formations urge the blade holder into the rear position relative to the housing in at least one region of movement of the blade holder. The first return formation includes a spring and a movable element connected to the spring and urged thereby in a travel direction of the movable element. The second return formation includes a counter surface engageable with the movable element.

Claims

1. A utility knife comprising: a housing; a blade holder movable between a front position and a rear position in the housing; and first and second return means of which one is mounted on the housing and the other is mounted on the blade holder, the first and second return means urging the blade holder into the rear position relative to the housing in at least one region of movement of the blade holder, the first return means including a spring and a movable element connected to the spring and urged thereby in a travel direction of the movable element, the second return means including a counter surface engageable with the movable element.

2. The utility knife according to claim 1, wherein the spring is a compression spring or a tension spring.

3. The utility knife according to claim 1, wherein the movable element interacts with the counter surface and the counter surface has a first surface directed in the travel direction of the blade holder such that the blade holder is urged with a first force in a first force range into the rear position.

4. The utility knife according to claim 3, wherein a second surface of the counter surface is directed in the travel direction of the blade holder such that the blade holder is urged with a second force in a second force range into the rear position.

5. The utility knife according to claim 4, wherein the second force range is less than the first force range and differs from the first force range.

6. The utility knife according to claim 1, wherein the surface is part of a control path traveled during movement of the blade holder between the rear position and a blade-change position.

7. The utility knife according to claim 1, wherein the movable element is a lever.

8. The utility knife according to claim 1, wherein the spring and the movable element are fastened to the blade holder, and one end of the spring is connected to the blade holder and another end of the spring is connected to the movable element.

9. The utility knife according to claim 1, wherein the spring and the movable element are fastened to the housing, and one end of the spring is connected to the housing and another end of the spring is connected to the movable element.

10. The utility knife according to claim 1, wherein the housing is provided with a first stop and a second stop and the blade holder is provided with a counter-stop, the first stop contacting the counter-stop in the front position and the second stop contacting the counter-stop in a blade-change position.

11. The utility knife according to claim 10, wherein the counter-stop can be moved toward the first stop on a first movement path and toward the second stop on a second movement path.

12. The utility knife according to claim 11, wherein the first movement path and the second movement path are separated by a wall at least in one region of movement of the counter-stop.

13. The utility knife according to claim 12, wherein the counter-stop and/or the wall are flexibly mounted such that the counter-stop can be moved between the first movement path and the second movement path.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the schematic drawings:

(2) FIG. 1 is a side view of the completely assembled utility knife, with the blade holder being in a rear position,

(3) FIG. 2 shows the utility knife based on FIG. 1, with the blade holder being in a cutting position,

(4) FIG. 3 shows the utility knife based on FIG. 1, with the blade holder being in a blade-change position and a blade cover being pivoted out from the blade seat,

(5) FIG. 4 is a side view of the utility knife according to FIG. 1, with a housing part not being shown,

(6) FIG. 5 is a side view of the utility knife according to FIG. 2, with a housing part not being shown,

(7) FIG. 6 is a side view of the utility knife according to FIG. 3 with a housing part not being shown,

(8) FIG. 7 is a sectional view along sectional line A-A in FIG. 4,

(9) FIG. 8 shows a detail according to detail line B in FIG. 6,

(10) FIG. 9 is a front view from the direction of the arrow C in FIG. 1,

(11) FIG. 10 is a side view of a second embodiment of the utility knife based on FIG. 4 in the rear position, with the return device being formed on the blade holder and the counter surface being formed on the housing,

(12) FIG. 11 is a side view of the second embodiment based on FIG. 5 in the cutting position,

(13) FIG. 12 is a side view of the second embodiment based on FIG. 6 in the blade-change position.

SPECIFIC DESCRIPTION OF THE INVENTION

(14) The utility knife as a whole is denoted by reference sign 10 in the drawings.

(15) According to FIG. 1, a first embodiment of the utility knife 10 comprises a housing 11 having a first housing part 12 and a second housing part 23. In addition, the utility knife 10 comprises a blade holder 13 having a blade 14, which is provided with a cutting edge 25. In the present embodiment, the housing part 23 is a sleeve and comprises a front opening 15 and a rear opening 16. A central longitudinal axis of the utility knife 10 is denoted by m.

(16) For actuating the blade holder 13, recesses 17a and 17b are also formed on either side in the housing part 23 in a front end region 18 of the utility knife 10. Two recesses are provided in the housing part 23 in a rear end region 19 of the utility knife 10, of which one recess 20 is used for actuating an actuating element 21 and the other recess 22 forms a through-opening that is used for hanging up the utility knife 10.

(17) In the present embodiment, the housing part 23 is a sheet-metal part, but can also be made of other materials and have a different shape. The invention does not come down to the material and external design of the housing, as becomes clear in the following.

(18) According to FIG. 1, the blade holder 13 is in the rear position. By the blade holder 13 being gripped by the recesses 17a and 17b, the blade holder 13 can be shifted relative to the housing 11 out of the rear position in the direction x.sub.1 into a cutting position, which is shown in FIG. 2. When the force on the blade holder 13 is decreased, the blade holder 13 is automatically moved into the rear position by a return device 34 when it is in a position between the rear position and the cutting position, with this including the cutting position.

(19) In order to prevent fingers from slipping, the blade holder 13 has a structure 24 that gives the fingers good grip on either side in its front end region.

(20) In addition, the blade holder 13 has an oblique cut-away portion 26, which exposes a region of the cutting edge 25 of the blade 14. In the present embodiment, the utility knife 10 has a rectangular blade 14, but any blade shape, such as a trapezoidal blade, hook blade, etc., can be used in principle.

(21) FIG. 1 also shows that the housing part 23 forms beads 54, which form recessed portions in the interior of the housing part 23, into which the housing part 12 can be latched.

(22) According to FIG. 3, the blade holder 13 is moved beyond the cutting position in the direction x1 into a blade-change position. The blade holder 13 can only be moved beyond the cutting position when the actuating element 21 has previously been actuated. In a known manner, the blade holder 13 comprises a main part 27, in which a blade seat 29 is formed, and a cover part 28, which forms a pivot joint G.sub.1 together with the main part 27. The blade 14 is held between the main part 27 and the cover part 28. In the blade-change position, it is possible to pivot the cover part 28 about a pivot axis a.sub.1 away from a blade seat 29, out of a closed position according to FIGS. 1 and 2 into an open position according to FIG. 3.

(23) FIG. 3 shows that the blade 14 is provided with a slot-shaped opening 30 and the blade seat 29 comprises a complementary projection 31, which engages through the blade 14 and can penetrate into a recessed portion 32 of the cover part 28 when the cover part 28 in is in the closed position. In this way, the blade 14 can be held in the blade holder 13 in a form-fitting manner. When the cover part 28 is in the open position, it is possible to remove the blade 14 from the blade seat 29 and replace it with a new blade 14.

(24) When the blade holder 13 is between the rear position and the cutting position, the cover part 28 is held in the closed position by opposite side walls 33a and 33b (not in the drawings) of the housing 11.

(25) FIG. 4 shows the utility knife 10 without the housing 11, with the blade holder 13 being in the rear position according to FIG. 1. A return device 34 urges the blade holder 13 into the rear position when the blade holder 13 is in the rear position, the cutting position, or between said positions.

(26) The rear position is defined by the contact between stop shoulders 46 of the blade holder 13 and a surface 47 of the first housing part 12 (cf. FIG. 4). First return means of the return device 34 comprise a spring 35, which is only indicated by a dashed-dotted line in FIGS. 4, 5 and 6. In addition, the first return means of the return device 34 comprise a movable element, in the form a lever 36 here. The spring 35 comprises a tension spring in the shape of a helical spring. One end of this spring is attached to a spring fastening 37 on the first housing part 12 and the other end of this spring is attached to a spring fastening 38 on the lever 36.

(27) The lever 36 is mounted on the first housing part 12 so as to be pivotable about a pivot axis a.sub.2 in the directions u.sub.1 and u.sub.2 and forms a pivot joint G.sub.2 together with the first housing part 12. The spring 35 urges the lever 36 in the direction u.sub.2. In the rear position according to FIG. 4, the spring 35 is subjected to pre-tensioning. The lever 36 comprises a projection 40, which is formed as a cylindrical pin in the present embodiment, but can also have a different design. An outer surface 41 of the projection 40 is in contact with a counter surface 42 of the blade holder 13. Second return means comprise the counter surface.

(28) In the present embodiment, the counter surface 42 forms a control surface that can influence the proportion of the spring force of the spring 35 depending on the position of the projection 40 relative to the counter surface, and this urges the blade holder 13 in the direction x.sub.2.

(29) The counter surface 42 of the blade holder 13 comprises a surface region 43 of which the surface orthogonal is directed approximately in parallel with the travel directions x.sub.1 and x.sub.2 of the blade holder 13. In addition, the counter surface 42 comprises a surface region 45 of which the surface orthogonal is directed approximately at right angles to the travel directions x.sub.1 and x.sub.2. A transition region 44 has an angle of approx. 45° to the region 43 and the region 45. The transition region 44 is arranged along the counter surface 42 between the surface regions 43 and 45 in relation to the travel directions of the projection 40.

(30) While the blade holder 13 is moving out of the rear position according to FIG. 4 into the cutting position according to FIG. 5, the outer surface 41 of the projection 40 abuts the first region 43 of the counter surface 42. Owing to the rotary movement of the lever 36 in the direction u.sub.1 counter to the force of the spring 35 in the direction u.sub.1, the projection 40 moves out of the position according to FIG. 4, through the position denoted by 40″ in FIG. 5, into the position denoted by 40 in FIG. 5.

(31) The cutting position is reached when an extension 49 of the blade holder 13 has moved on a first movement path into contact with a counter surface of a first stop 48 on the first housing part 12.

(32) If the blade holder 13 is to be moved into a blade-change position, the first stop 48 can be moved by means of the actuating element 21 in a resilient manner in the direction y.sub.1 on a second movement path, which is separated from the first movement path by a wall 55. The blade holder 13 can then be moved on the second movement path into the blade-change position according to FIG. 6. Movement of the blade holder 13 in the direction x.sub.1 is limited by the contact between the surface of the extension 49 and a holding surface of a second stop 50. If the blade holder 13 is moved back into the rear position in the direction x.sub.2, the extension 49 is automatically moved back onto the first movement path due to its resilient return force.

(33) While the blade holder 13 is moving between the cutting position and the blade-change position, the projection 40 slides from the first region 43, through the transition region 44, onto the second region 45. The surface orthogonal of the second region 45 is directed at right angles to the travel directions x.sub.1, x.sub.2 of the blade holder 13, such that no forces can be transferred from the lever 36 to the blade holder 13 which load the blade holder in the direction x.sub.2. The blade can therefore be changed without the blade holder 13 having to be held in the blade-change position counter to the spring force of the spring 35. The spring force that is transferred from the lever 36 to the blade holder is absorbed by the housing part 23 in this position of the projection 40.

(34) Once the blade change is completed, the blade holder 13 is moved out of the blade-change position manually relative to the first housing part 12 in the direction x.sub.2. The projection 40 then slides in the opposite direction from the region 45 of the counter surface 42, through the transition region 44, onto the region 43. When the transition region 44 is reached, the lever 36 again exerts a force in the direction x.sub.2 on the blade holder 13, such that the further movement of the blade holder 13 in the direction x.sub.2 until it reaches the rear position no longer has to be actively performed by the user, but instead takes place automatically by means of the return force of the spring 35 which urges the lever 36 in the direction u.sub.2. The rear position is reached when the stop shoulders 46 abut the surfaces 47 of the second housing part 23.

(35) The utility knife is assembled as follows, for example. The lever 36 is put onto a pin 51 of the first housing part 12 forming the pivot axis a.sub.2. The spring 35 is fastened to the lever 36 and the first housing part 12. The cover part 28 is mounted on the main part 27 of the blade holder 13.

(36) The blade holder 13 is then inserted into the first housing part 12 and the projection 40 of the lever 36 is brought into contact with the region 45. By being inserted further in the direction x.sub.2, said blade holder comes into contact with the transition region 44, at which point the blade holder 13 is automatically moved into the rear position.

(37) The unit made up of the first housing part 12 and the blade holder 13 can then be inserted into the rear opening 16 in the housing 11 until a stop surface 52 of the first housing part 12 abuts a rear end face 53 of the housing 11 and the housing part 12 is latched to the housing part 23.

(38) The blade 14 can then be mounted by the blade holder 13 being moved into the blade-change position as described above.

(39) FIGS. 10 to 12 show a second embodiment of the utility knife, which only differs from the first embodiment in that the spring 35′ and the lever 36′ are formed on the blade holder 13′ and the control surface 42′ is formed on the housing part 12′. Otherwise, the corresponding components or elements have been provided with the numbers that have also been used in the first embodiment, with these numbers additionally containing an apostrophe.