Vertical Alignment Curved Liner Spring for Knife Handle

Abstract

The liner for the folding knife includes a curved and elongated spring that biases the blade of the knife to an open position or a closed position. The spring can extend in an arc from a starting point to a free end within a notch region of the liner body. The spring may be J-shaped in one approach. The spring may be integrally formed with the liner or formed as a separate piece attached to the liner. The free end can include a shoe that contacts a lock stud of the knife handle. The starting point can be below and in front of the shoe. The spring biases the lock stud forward to lock the blade in the open position. To close the blade, the user moves the lock stud rearward against the spring force of the spring, allowing the blade to rotate to the closed position.

Description

Background Art

[0001] [Cross - Reference to Related Applications]

[0002]

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 393,099, filed Jul. 28, 2022, which is incorporated herein by reference. [Technical Field]

[0003]

[0002] The present disclosure relates to the field of knives, and more particularly, to a liner for a knife, the liner having an integral spring. [Background]

[0004]

[0003] Knives are available in a variety of designs for various purposes. Generally, a knife can be composed of either a fixed blade or a folding blade. Folding - blade knives are more convenient for many applications due to their more compact size. To improve safety and convenience, some folding - blade knives employ a spring mechanism that biases the blade to an open or closed position. A locking mechanism for locking the blade in the open position can also be provided. However, existing spring mechanisms have relatively low wear resistance, occupy additional space, and are susceptible to maintenance problems.

Brief Description of the Drawings

[0005]

[0004] Embodiments of the present disclosure will be more fully understood from the following detailed description given below and from the accompanying drawings of various embodiments of the present disclosure, but should not be construed as limiting the present disclosure to specific embodiments, which are for illustrative and understanding purposes only.

Figure 1

Figure 2

Figure 3A

Figure 3B

[0006] As described above, typically two liners of the same type are provided within the handle, one on each side of the tang.

Figure 3C

Figure 4

Figure 5

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Figure 7

Figure 8A

Figure 8B

Figure 9

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Figure 12B

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Figure 13B

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Figure 17

[0007] Detailed Description

[0008]

[0039] In the following detailed description, reference is made to the accompanying drawings which form a part hereof and which are shown by way of illustrative exemplary embodiments. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Accordingly, the following detailed description is not to be taken in a limiting sense, and the scope of the embodiments is defined by the appended patent claims and their equivalents.

[0009]

[0040] The various operations are described serially as a plurality of individual operations in a manner that may be useful in understanding the embodiments. However, the order of the description should not be construed to mean that these operations are order dependent.

[0010]

[0041] (For the description, descriptions based on a balanced view such as up / down, back / front, top / bottom, etc. can be used. Such descriptions are used merely to facilitate the discussion and are not intended to limit the application of the disclosed embodiments.

[0011]

[0042] The terms "coupled" and "connected" are used along with their derivatives. It should be understood that these terms are not intended to be synonyms of each other. Rather, in a particular embodiment, "connected" is used to indicate that two or more elements are in direct physical contact with each other. "Coupled" may mean that two or more elements are in direct physical contact with each other. However, "coupled" may also mean that two or more elements are not in direct contact with each other but still cooperate or interact with each other.

[0012]

[0043] For purposes of explanation, a phrase in the form of "A / B" or "A and / or B" means (A), (B), or (A and B). For purposes of explanation, a phrase in the form of "at least one of A, B, and C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). For purposes of explanation, a phrase in the form of "(A)B" means (B) or (AB), i.e., A is an arbitrary element.

[0013]

[0044] In this description, the terms "embodiment" or "embodiments" can be used, and each of these terms can refer to one or more of the same or different embodiments. Further, terms such as "comprising", "including", "having", etc. used with respect to embodiments are synonymous.

[0014]

[0045] As described at the beginning, various challenges are presented when providing a spring mechanism for a folding knife. One approach is to use a horseshoe-shaped (or omega-shaped with reference to the Greek symbol "Ω") locking spring attached to liners on both sides of the handle of the knife to bias a lock bar that moves within a slot when the blade is opened and closed. For example, referring to U.S. Patent No. 9,862,104 issued on January 9, 2018, a horseshoe-shaped locking spring attached to a liner to bias the lock bar is disclosed. Another approach includes a liner lock spring that extends along the length of the handle, typically on one side of the handle, and a safety spring that extends along the length or edge of the handle. However, these approaches have disadvantages with respect to wear resistance, space requirements, and maintenance issues.

[0015]

[0046] The devices described herein address the above and other problems. In one aspect, a liner for a folding knife includes a vertically oriented spring as part of one or both liners within the knife handle. The vertically oriented spring is curved, elongated, and may be, for example, a J-shaped spring, although other shapes are possible. The spring may be formed from the same sheet of metal or other material from which the liner is formed, or the spring may be formed as a separate part that is attached to the liner and secured to the liner, such as by friction fitting. The spring can have characteristics as described herein that provide a good feel to the user when opening and closing the blade, based on factors such as the amount of tension required to open and close the blade. The spring can be configured to bias a lock stud that moves within a slot in the handle when the blade is opened and closed, and the lock stud contacts a tang of the blade. Thus, the spring biases the blade toward the open and closed positions for safety.

[0016]

[0047] The liner designs described herein are similarly expected to have a significantly increased lifespan, allowing for a significantly greater number of opening and closing cycles for the knife blade compared to previous designs.

[0017]

[0048] Also, the liner design allows for a thinner handle width because the spring is integrated into or attached to the liner in a notch region within the plane of the liner. Further, using a vertical spring can shorten the horizontal length of the liner, allowing for various design options for the handle.

[0018]

[0049] The above and other advantages will become more apparent from the following description.

[0019]

[0050] FIG. 1 is a side view of an example knife 100 according to various embodiments. The knife includes a blade 101 and a handle 102 and extends along a longitudinal axis LA. The bolster 105 of the handle includes a pivot point PP or axis about which the blade can rotate and a slot 115 through which a lock stud 120 can move in a forward or backward direction. In one approach, the lock stud is in the forward direction when the blade is in the open or closed position and temporarily moves in the backward direction when the blade is in an intermediate or partially open position. In particular, the lock stud can interact with a tang of the blade to lock the blade in the open position or rotate the blade to the closed position. A spring mechanism can apply a force to the tang via the lock stud to assist the user in opening and closing the blade.

[0020]

[0051] The forward direction is, for example, the direction toward the front of the knife or the blade tip and is parallel to the longitudinal axis. The backward direction is, for example, the direction opposite to the forward direction and is the direction toward the back of the knife. Referring to an x - y coordinate system, the forward direction is the x - direction and the backward direction is the - x direction. The vertical direction can be the y - direction.

[0021]

[0052] The thumb button 130 is engagable by the user's thumb to assist in moving the blade to the open or closed position. The handle includes a number of fasteners 140-143 to secure the opposing side portions of the handle together. The fastener 140 also acts as a stop pin.

[0022]

[0053] The folding blade knife can be used for various purposes at home, during cooking, and outdoors. Such a knife is sized to fit in a typical user's hand and is, for example, about 4-5 inches (101-127 mm) in length with the blade closed or about 7-8 inches (178-203 mm) in length with the blade open.

[0023]

[0054] FIG. 2 is a side view of a portion of the knife of FIG. 1 including the liner 200 according to various embodiments. Typically, two liners of the same type are provided in the handle, one on each side of the tang. The liner is attached to the handle shell or cover using fasteners 220. The blade 101 includes a tang 210 attached to the hub 103 so as to pivot about the pivot point PP. The tang includes a top shoulder 211 that abuts the fastener / stop pin 140 when the blade is in the fully open position. The stop pin prevents the blade from rotating clockwise. The tang also includes a bottom shoulder 214. The tang also includes a straight inclined portion 212 that contacts the lock stud 120 when the blade is in the fully open position. The lock stud prevents the blade from rotating counterclockwise as long as the lock stud is in the forward position within the slot. A spring mechanism (not shown) biases the lock stud to the forward position to keep the blade safely locked when in the open position.

[0024]

[0055] As depicted by the lock stud 120r, when the user manually moves the lock stud to the rear position, the tang can rotate freely to move the blade to the closed position. When the tang rotates counterclockwise, the rounded portion 213 of the tang contacts the lock stud, allowing the lock stud not to interfere with the rotation of the blade. The lock stud is pushed rearward by the rounded portion 213 of the tang, as a result, the force applied to the spring mechanism increases. The forward position of the lock stud is the lock load position because the blade is locked. The spring mechanism can apply a relatively small force to the lock stud to maintain the lock stud at the forward lock load position. The rear position of the lock stud is the maximum (max) load position because the load on the spring mechanism is the greatest. The CLR refers to the cyclic load range which is the difference between the maximum load and the lock load.

[0025]

[0056] The following definitions can be created. "Lock-up load" or "Lock load": The sum of the forces applied to the lock stud by the springs of both liners at the lock load position. This includes preload and wear tolerances. "Maximum load": The sum of the forces applied to the lock stud by both springs at the maximum load position. This is when the lock stud is in the most rearward position of the knife handle and includes any extra movement at the end. "Cyclic load range (CLR)": The difference between the maximum load and the lock load, i.e., ([Spring constant]) X ([Stroke]). "Total length of stroke" or "Stroke": The distance the lock stud moves from the lock load position to the maximum load position.

[0026]

[0057] FIG. 3A is a side view of a portion of an exemplary knife liner 300 that includes an integral vertically elongated spring 310 according to various embodiments. In one approach, two such liners are provided, one on each side of the knife handle. The liner includes an opening 305 for a stop pin and an opening 335 for a hub. The pivot point PP is also depicted.

[0027]

[0058] In this embodiment, the spring 310 is formed as a single sheet metal integrally with the liner. For example, a curved and elongated spring is formed as a single piece integrally with the liner body. In other embodiments, the spring is formed separately from the liner and attached to the liner during its manufacture. For example, a curved and elongated spring is a separate part attached to the liner body.

[0028]

[0059] In this embodiment, the spring is generally J-shaped, but it can also have other shapes. The spring can generally be curved. The spring can be oriented in the vertical direction in that its height is greater than its total horizontal width. The spring extends from a connection point or origin 355 into a notch region 340 within the liner body. This point can be located below and in front of the pivot point. The spring, also called a lever arm, extends in an arc downward from its origin to a point directly below the pivot point and then upward to a point above and to the right of the pivot point. Note that in this figure, the front of the knife handle is to the left and the rear is to the right. This convention applies similarly to other line drawings in this specification. In this embodiment, the spring is depicted in three positions. Spring 311 represents the punching position where the spring is formed. In this position, no load is applied to the spring. The spring includes a shoe 311a with a surface 311b on which the lock stud can rest. Spring 312 represents the lock load position, and the spring is under a relatively small load while the lock stud 120 is stationary with respect to the surface of the shoe. Spring 313 represents the maximum load position where the spring is under the maximum load while the lock stud 120r is stationary with respect to the surface of the shoe.

[0029]

[0060] In an embodiment, a triangular region 350, called a lock-up triangle, is substantially intact with respect to strength. The liner includes an inner portion 300int adjacent to the opening 335 on one side of the notch region and an outer portion 300ext on the opposite side of the notch region. The notch can extend to the outer periphery of the liner and need not enclose it. For example, refer to FIG. 4.

[0030]

[0061] The stopper 320 is a bump within the wall 330 of the notch for restricting the rearward movement of the spring and the shoe. In this embodiment, the bump extends towards the front of the knife. All contacts between the spring and the liner need to be behind the shoe. It is not desirable for the center of the spring to contact the liner. The spring can extend up to the outer circumference in the deformed (maximum load) state, but cannot extend in the neutral (locking load) state.

[0031]

[0062] Figure 3B is a view in the direction of arrow 360 of Figure 3A according to various embodiments. This figure depicts two of the curved and elongated liners 300, the lock stud 120, and the hub 103 as the first liner 300a and the second liner 300b respectively. As described above, two liners of the same type can be provided on each side of the tang, one on each side, on the handle. The lock stud and the hub can extend through the liner and be slightly longer than the spacing sp between the liners. The liners are separated from each other by sp. The lock stud can extend outward from the liner so that the user can operate the lock stud with the thumb when closing the blade. The hub can be fixed to the liner, and the lock stud protrudes beyond the liner and can move forward and backward with minimal friction.

[0032]

[0063] Figure 3C depicts a perspective view of the liner 300 of Figure 3A showing the cross-sectional thickness (Th) according to various embodiments. As described above, in one possible approach, the spring can be punched from the same sheet metal as the body of the liner such that the body of the spring and the liner have the same thickness. The width (w) of the spring is also depicted. Alternatively, the thickness of the spring and the liner body may be different.

[0033]

[0064] Figure 4 is a side view of a portion of liner 300 of an embodiment similar to liner 370 of FIG. 3A, but according to various embodiments, the liner includes an opening 380. As described above, the cutout region 390 of the liner can extend to the outer periphery of the liner and need not be surrounded by the spring. This approach can enable weight reduction and provide space for design changes. The spring has a bend point 450, which refers to a point on the spring where the bend radius is minimal.

[0034]

[0065] The spring design requirements for a number of embodiments can be set. For example, with respect to stress, a requirement may be made that the liner can withstand 100k opening and closing cycles without taking a set and can withstand one opening and closing cycle during assembly without taking a set. "Taking a set" means that stress is applied to the spring arm until a point where permanent plastic deformation occurs. An example of the material of the liner is a metal such as heat-treated 410 SS. This refers to alloy 410 (UNS S41000), which is a 12% chromium martensitic stainless steel sheet. However, many other materials are possible. In one approach, the metal is sheet metal. Also, when the spring is formed separately from the liner, the spring can be formed of a different material than the liner.

[0035]

[0066] An example of a yield strength of 186 kilopounds per square inch (ksi) (1,282 mPa) was used as a limit in a finite element analysis study of an apparatus using 410SS metal. An ultimate strength of 216 ksi (1,489 mPa) was also used.

[0036]

[0067] The design requirements for another embodiment include displacement / full stroke length. For example, the total stroke distance of the lock stud, which is the value obtained by adding a minimum clearance of 0.015” to the displacement of the tang. An example of the stroke length is 0.1028 inches (0.0678 inches stroke + 0.020 inches diameter increase for sack back + 0.015 inches minimum bonus clearance) for lock engagement. Sack back refers to the action of the spring that biases the blade towards the closed position. Note that other axial lock designs had a total stroke length of approximately 0.200 inches (longer stroke, more overtravel / bonus clearance). To obtain the optimal sack back, it is necessary to increase the stroke length.

[0037]

[0068] Regarding the spring rate, also known as the spring constant, a lower value is more suitable to create a similar feel with “lock load” and “maximum load”. An example of a general target is a total of 10 pounds per inch (1751 N / m), or 5 pounds per inch (875 N / m) per liner. The spring constant is usually described as the total when using two liners in the handle of the knife. The spring constant in this document follows this convention.

[0038]

[0069] Regarding the force design requirements, one approach is to start with a lock load target of approximately 1.0 pound (44.4 N). This can be increased as needed. The CLR (depending on spring design and total stroke length) is ideally less than 1.0 pound (44.4 N) in one approach. Once the lock load target and CLR are set, the maximum load can be freely adjusted within the allowable stress range. Usually, in the lock load state, the force is at least 0.15 pounds (0.67 N) per liner (total 0.3 pounds or 1.33 N).

[0039]

[0070] In other desirable design requirements, corrosion resistance, ease of assembly, reasonable manufacturing / processing costs, the ability of the lock stud to move along the slot without excessive friction, and ensuring that the lock stud does not fall below the top edge of the slot or liner opening are included. That is, the lock stud should be held against the top wall / edge of the notch region of the liner by the spring shoe.

[0040]

[0071] Figure 5 depicts a liner design 500 of an embodiment where the spring 510 is a separate component attached to the liner 540, according to various embodiments. Instead of integrating the spring and the liner as a single component, the spring can be punched from a sheet metal different from the punching of the liner. The spring is then firmly fitted and installed into the liner, for example, by friction fitting or press fitting, or attached to the liner by other means. This can provide advantages such as allowing the spring to be formed of a different material than the liner and / or having a different thickness than the liner. Different materials and / or thicknesses can be designed to optimize the characteristics of the spring with respect to spring constant and durability. Also, it is easier to punch the spring and the liner separately.

[0041]

[0072] Potentially, the spring is replaceable after the knife is manufactured, for repair or to allow the user to customize the characteristics of the knife. For example, the user may desire to have a greater or lesser force when opening and closing the blade by attaching springs with greater or lesser spring constants, respectively. In this design, the spring may be replaceable.

[0042]

[0073] The spring is long and curved in this embodiment and has three bending points 550, 551, and 552.

[0043]

[0074] Spring 510 includes an end portion 510a that fits within an opening 541 of corresponding shape within the liner at spring origin 555. The spring also includes a free portion 510b that extends from the origin to the free end. At the free end, shoe 520 includes, on its face, a groove or recess 521 for holding lock stud 120. Since the groove faces upward, the spring tends to hold the lock stud against top wall 542 of the liner, preventing a click sound when the lock stud moves away from and then snaps back against the top wall. A stopper 530 is also depicted to limit rearward movement of the spring at the maximum load position. The spring is shown at the lock load position.

[0044]

[0075] Figure 6 depicts a chart showing the range of forces on an integrated elongate spring, according to various embodiments, with a less desirable spring design. Such a spring design has a relatively large CLR, with few options for achieving the desired force to bias the lock stud and must operate at or near the maximum stress capacity of the spring. The chart shows that the lock load (LL) force (left bar extending from 0 - 0.9 lb or 0 - 4.0 N) is approximately 0.9 lb (4.0 N), the CLR force is approximately 1.7 lb or 7.5 N (central bar extending from 0.9 - 2.6 lb or 4.0 - 11.5 N), and the remaining maximum stress (MS) margin is only approximately 0.1 lb or 0.44 N (right bar extending from 2.6 - 2.7 lb or 11.5 - 12.0 N).

[0045]

[0076] Figure 7 depicts a chart showing the range of forces on an integral elongated spring with a more preferred spring design according to various embodiments. A good spring design has a relatively small CLR, has many options for achieving the desired force to bias the lock stud, and avoids the need to operate at or near the spring's maximum stress capacity. The chart shows that the lock load force (left bar extending from 0 - 1.0 lb or 0 - 4.4 N) is approximately 1.0 lb (4.4 N), the CLR force is approximately 0.8 lb or 3.5 N (central bar extending from 1.0 - 1.8 lb or 4.4 - 8.0 N), and the remaining maximum stress margin is approximately 0.5 lb or 2.2 N (right bar extending from 1.8 - 2.3 lb or 8.0 - 10.2 N). Thus, the force of the spring on the lock stud is 1.0 pound (4.4 N) at the spring's lock load position and 1.8 pounds (8.0 N) at the spring's maximum load position. The spring can be designed to set the lock load force or the maximum load force to a desired level. The maximum stress margin represents an optional load range.

[0046]

[0077] The design process can proceed as follows. First, set the lock load target to approximately 1.00 lb (4.4 N). Second, aim to minimize the CLR by minimizing the cross-sectional area of the lever arm, maximizing the vertical length and total arc length of the lever arm, and minimizing the stroke such as in a through-blade tang design. Third, if the stress at the maximum load exceeds the stress limit (e.g., 186 ksi or 1,282 mPa), adjust the above. The lock load target may need to be increased for a heavy blade to achieve the desired sackback to the closed position.

[0047]

[0078] FIG. 8A depicts a side view of a liner 800 in which a J-shaped spring 805 has a stopper 810, according to various embodiments. As described above, it is convenient to have a stopper that limits the maximum deflection of the spring. The stopper allows for maximum displacement but no more, so that no setting is taken during assembly. For example, the spring arm is not stressed to the point where permanent plastic deformation occurs. Instead, the spring arm can return to its original shape. In this embodiment, the stopper is on the back side of the shoe. In other embodiments, the stopper is part of the liner, such as the stopper 320 of FIG. 3A.

[0048]

[0079] FIG. 8B depicts a side view of the liner 800 of FIG. 8A during manufacture, in which a tab 820 has been added for stability, according to various embodiments. The tab can be punched out of the spring with sheet metal. The tab holds the spring during manufacture and is then removed, for example, by cutting.

[0049]

[0080] FIG. 9 depicts the liner 800 of FIG. 8A with the spring in the lock load position and the maximum load position, according to various embodiments. The stopper 810 is provided on the back side (rear end side of the handle) of the J-shaped spring 805, rather than on the rear wall of the liner. The lock load position is represented by the spring 805 and the lock stud 120, and the maximum load position is represented by the spring 805a and the lock stud 120r.

[0050]

[0081] The flat shoe surfaces 910, 930 help hold the lock stud against the top wall of the slot as compared to the concave shoe surfaces of FIG. 3A. In the flat shoe surface, as the lock stud moves rearward, the lock stud winds up the shoe surface. Thereby, the lock stud is held against the top surface of the slot. Also, in this design, the movement of the lock stud becomes larger with respect to the amount of deflection of the spring, and a "softer" spring constant can be obtained without applying stress to the spring.

[0051]

[0082] Further, the liner is formed with material 920 at the upper right corner of the opening so that the lock stud does not pass through the shoe.

[0052]

[0083] In contrast, the design of FIG. 3A has the lock stud located in the concave surface of the shoe, which can be pulled away from the upper wall of the liner when the shoe is pulled back and then bounce back to hit the wall, which may produce a clicking sound.

[0053]

[0084] FIG. 10 is a side view of a tang 1000 with a hook of the knife of FIG. 2 according to various embodiments. In this tang design, the hook 1001 has a tendency to capture or catch the lock stud 120. This contributes to pulling the lock stud away from the top wall of the slot and may generate an undesirable clicking sound when using the knife.

[0054]

[0085] FIG. 11 is a side view of a tang 1100 without a hook of the knife of FIG. 2 according to various embodiments. This is a modified blade tang design that can solve the click problem of FIG. 10 by rounding the tip of the hook to provide a rounded area 1101.

[0055]

[0086] FIG. 12A depicts the liner 800 of FIG. 8A showing various features according to various embodiments. The radius of the spring, also called the bend radius, varies at different points along the spring. FIG. 12A shows different bend radii r1 - r3 at three example points. The bend radius gets shorter as the bend gets tighter and longer as the bend radius gets looser. r1 is the radius at the starting point of the spring. The spring has a minimum bend radius at some point along its length. In some cases, the minimum bend radius is at or near the bottom of the spring. At the minimum bend radius, stress concentrates, which determines the spring constant and stress. Some springs have a relatively constant bend radius over most of their length, some have one main bend region with a constant radius and intentionally reduce the bend radius in one region to promote a local bending point. In all these cases, the minimum bend radius remains important.

[0056]

[0087] The starting point of the spring refers to the point on the shoe surface that contacts the lock stud. For example, this is the center of the shoe surface. The shoe is at the free end (FE) of the spring. A stopper (PS) protrudes on the rear side of the shoe. The shoe angle is the angle of the shoe surface with respect to the vertical, in the clockwise direction from the vertical. The horizontal is, for example, a direction parallel to the longitudinal axis (LA) of the knife handle (see FIG. 1) extending along the longitudinal direction of the knife handle, and the vertical (y-axis) is a direction perpendicular to the horizontal (x-axis) and the longitudinal axis. The starting point vertical offset is the vertical distance between the starting point of the spring and the starting point of the shoe surface. The starting point angle (OA) is the angle of a straight line drawn in the clockwise direction in the figure with respect to the perpendicular line between the starting point of the spring and the starting point of the shoe surface. In this embodiment, the starting point angle is about 230 degrees, for example, greater than 225 degrees. In this embodiment, the number of bends of the spring is 1. In other embodiments, the spring has a plurality of bends in the opposite direction. For example, refer to the liner design 1620 in FIG. 16. The starting point horizontal offset is the horizontal distance between the starting point 1201 of the spring and the starting point 1202 of the shoe surface.

[0057]

[0088] FIG. 12B depicts the liner 800 of FIG. 8A showing various features according to various embodiments. The total vertical height of the spring is the vertical distance between the lowest point (BP) of the spring and the starting point of the shoe surface. The total horizontal width of the spring is the horizontal distance between the starting point of the spring and the most rearward point (rp). The total arc length (AL) of the spring is the distance along the spring from the starting point to the origin of the shoe face. The total spring arc length (AL) is the distance along the spring from the starting point to the starting point of the shoe surface.

[0058]

[0089] Regarding the optimization of the spring and the liner, several observations can be made. First, thinner and narrower springs have a lower spring constant and lower stress at the maximum load position, which is desirable. The spring constant is a strong function of the thickness and width of the lever arm. Reducing the width reduces the stress, but changing the thickness has no effect on the stress. One approach is to use the minimum spring thickness and width to optimize the CLR at a low level while reducing stress, unless there is another reason to increase the thickness and / or width. The minimum spring thickness and width are based on the thickness of the untreated sheet material.

[0059]

[0090] Another observation is that a softer (more gradual) bend point of the spring results in a smaller CLR at a similar stress, while a sharper (less gradual) bend point of the spring results in a smaller CLR but a higher stress. The optimal spring shape varies depending on the knife form factor. In some cases, a minimum bend radius in the range of about 2 mm (0.08 inches) to about 5 mm (0.20 inches) functions well. The bend radius can be varied along the spring so that the minimum bend radius is at the sharpest bend point along the length of the spring arc. Thus, making the bend point tighter increases the stress but decreases the spring constant.

[0060]

[0091] Another observation is that a higher starting point of the spring and a larger arc length of the spring contribute to reducing the spring constant.

[0061]

[0092] Another observation is that a larger vertical height significantly reduces the spring constant. In fact, increasing the vertical height of the spring is the single largest factor in reducing the spring constant. The effect of the vertical height is greater than the effect of the starting point when reducing the spring constant. However, increasing the vertical height causes the minimum bend radius to become too flat (too large), increasing the spring constant. For example, refer to the liner design in Figure 14.

[0062]

[0093] Here, the test data of the J-shaped spring will be described.

[0063]

[0094] In FIGS. 13A - 13J, the points enclosed by circles represent a liner / spring thickness of 0.040 inches (1.016 mm) and a spring width of 0.025 inches (0.635 mm), and the other points represent a liner / spring thickness of 0.050 inches (1.270 mm) and a spring width of 0.030 inches (0.762 mm). The unit of the spring constant is pounds per inch or N / m. The unit of length is inches or mm.

[0064]

[0095] FIG. 13A depicts a plot of spring constant versus total spring vertical height for various liner designs, according to various embodiments. The data shows that there is a very strong correlation between the vertical height of the spring and the spring constant. In particular, the spring constant decreases as the vertical height increases.

[0065]

[0096] The outlier point 1300 results from a flat bending radius and a starting angle close to 180 degrees.

[0066]

[0097] The spring constant ranges from 5 - 19 lb / in or 3327 N / m, and the total vertical height ranges from 0.400 - 1.200 in or 10 - 30 mm.

[0067]

[0098] FIG. 13B depicts a plot of spring constant versus total spring horizontal width for various liner designs, according to various embodiments. There is a slight correlation, but not a strong correlation, between the horizontal width and the spring constant. In particular, the spring constant decreases as the horizontal width increases.

[0068]

[0099] The spring constant ranges from 5 - 19 lb / in or 875 - 3327 N / m, and the horizontal width ranges from 0.300 - 0.750 in or 7.6 - 19 mm.

[0069]

[0100] Figure 13C depicts plots of spring constant versus total spring arc length for various liner designs in accordance with various embodiments. There is a very strong correlation between arc length and spring constant. In particular, as the arc length increases, the spring constant decreases. Outlier point 1310 results from a short vertical height.

[0070]

[0101] The spring constant ranges from 5 to 19 lb / in or 875 to 3327 N / m, and the total arc length ranges from 0.600 to 2.000 in or 15 to 51 mm.

[0071]

[0102] Figure 13D depicts plots of spring constant versus minimum bend radius for various liner designs in accordance with various embodiments. There is a strong correlation between minimum bend radius and spring constant. In particular, as the bend radius decreases, the spring constant decreases. Point 1320 shows how the difference between springs with the same minimum bend radius varies with vertical height. Point 1325 has a very high vertical height above the flat bend radius and thus has better performance.

[0072]

[0103] The spring constant ranges from 5 to 19 lb / in or 875 to 3327 N / m, and the bend radius ranges from 0.000 to 1.000 in or 0 to 25 mm.

[0073]

[0104] Figure 13E depicts plots of spring constant versus the distance from the origin to the shoe for various liner designs in accordance with various embodiments. There is no correlation, indicating that distance is not a significant variable.

[0074]

[0105] The spring constant ranges from 5 - 19 lb / in or 875 - 3327 N / m, and the distance ranges from 0.400 - 1.200 in or 10 - 30 mm.

[0106]

[0075]

[0107] Figure 13F depicts plots of spring constant versus base point angle for various liner designs according to various embodiments. There is a correlation between the starting angle and the spring constant. In particular, the spring constant decreases as the starting angle increases. Outliers 1330 and 1335 are due to another important variable being in a bad location. For example, these two points represent the vertical height of a very short spring.

[0076]

[0108] The spring constant ranges from 5 - 19 lb / in or 875 - 3327 N / m, and the starting angle ranges from 180 - 250 degrees.

[0077]

[0109] Figure 13G depicts plots of spring constant versus starting point horizontal offset for various liner designs according to various embodiments. There is a slight correlation, but not a strong correlation, between the starting point horizontal offset and the spring constant. In particular, the spring constant decreases as the starting point horizontal offset increases.

[0078]

[0110] The spring constant ranges from 5 - 19 lb / in or 875 - 3327 N / m, and the horizontal offset ranges from 0.200 - 0.700 in or 5 - 18 mm.

[0079]

[0111] Figure 13H depicts plots of spring constant versus starting point vertical offset for various liner designs according to various embodiments. There is no correlation, indicating that the starting point vertical offset is not an important variable.

[0080]

[0112] The spring constant ranges from 5 - 19 lb / in or 875 - 3327 N / m, and the vertical offset ranges from 0.100 - 1.100 in or 3 - 28 mm.

[0081]

[0113] Figure 13I depicts a plot of the ratio of the spring vertical height to the total liner vertical height against the spring constant of the liner of the example according to various embodiments. There is a strong correlation between the ratio and the spring constant. In particular, as the ratio increases, the spring constant decreases. Generally, to lower the spring constant, it is appropriate to make the ratio greater than 0.4. It gets even better when it exceeds 0.5. There is no upper limit, and the higher the ratio, the better. The total vertical height represents the maximum vertical range of the liner when the vertical direction is perpendicular to the longitudinal axis in one approach.

[0082]

[0114] In an embodiment, the ratio of the vertical height of the curved elongated spring to the vertical height of the liner is at least 0.4 or 0.5.

[0083]

[0115] The spring constant is in the range of 5 - 30 lb / in or 875 - 5253 N / m, and the ratio is in the range of 0.30 - 0.75.

[0084]

[0116] Figure 13J depicts a plot of the ratio of the arc length to the total vertical height of the liner for the example of Figure 13I against the spring constant according to various embodiments. There is a strong correlation between this ratio and the spring constant. In particular, as the ratio increases, the spring constant decreases. Generally, a value greater than 0.5 is suitable to lower the spring constant. It gets even better when it exceeds 0.6. There is no upper limit, and the higher the ratio, the better.

[0085]

[0117] In an embodiment, the ratio of the arc length of the curved elongated spring to the vertical height of the liner is at least 0.5 or 0.6.

[0086]

[0118] The spring constant is in the range of 5 - 30 lb / in or 875 - 5253 N / m, and the ratio is in the range of 0.40 - 1.20.

[0087]

[0119] Figure 13K depicts a table of examples of spring constants and stress values according to spring dimensions, in accordance with various embodiments. The data was obtained from springs with vertical heights of 0.53 inches (13 mm), 0.59 inches (15 mm), 1.00 inches (25 mm), and 1.08 inches (27 mm), and is generalized in the table to vertical heights of 0.5 inches (13 mm), 0.7 inches (18 mm), 0.9 inches (23 mm), and 1.1 inches (28 mm).

[0088]

[0120] The first column depicts the spring dimensions in inches (in.) and mm as thickness (th) × width (w), the second through fifth columns represent the spring constants for different vertical heights in lb / in and N / m, and the sixth through ninth columns represent the spring stress at a displacement of 0.150 inches (3.8 mm) for different vertical heights in ksi and MPa.

[0089]

[0121] The liner thicknesses considered were 0.030 inches (0.762 mm), 0.040 inches (1.016 mm), 0.050 inches (1.270 mm), 0.060 inches (1.524 mm), and 0.070 inches (1.778 mm). These thicknesses refer to the thickness of the finished liner, not the raw material. The spring width was varied (0.020 - 0.040 inches, or 0.508 - 1.016 mm) along with the liner thickness due to typical manufacturing capabilities. The ideal spring constant range is, for example, 3.0 - 15.0 pounds per inch (525 - 2626 N / m).

[0090]

[0122] In this example, the maximum allowable stress is 186 ksi or 1,282 mPa. A constant total displacement of 0.150” or 3.8 mm was used for stress calculations (maximum load position including preload).

[0091]

[0123] Generally, the spring constant decreases as the vertical height of the spring increases, and increases as the thickness and width increase. Also, the stress decreases as the vertical height of the spring increases, and increases as the thickness and width increase.

[0092]

[0124] Figure 13L depicts, according to various embodiments, a plot of spring constant and spring vertical height as a function of liner thickness that matches the table of Figure 13K. Plots 1350 - 1353 represent spring vertical heights of 0.5 inches (13 mm), 0.7 inches (18 mm), 0.9 inches (23 mm), and 1.1 inches (28 mm), respectively. Ideal spring constant ranges are, for example, about 3 - 15 pounds per inch (525 - 2626 N / m), about 2 - 25 pounds per inch (350 - 4378 N / m), or about 5 - 20 pounds per inch (875 - 3502 N / m). Generally, the liner thickness affects the spring constant to the extent (but not more than) of the vertical spring height. The shorter the spring, the more susceptible it is to the influence of the liner thickness. With an appropriate liner thickness, all spring heights will result in an appropriate spring constant. However, considering the theoretically possible range, not all spring thicknesses / widths can be manufactured in a practical way. The spring width was varied along with the spring thickness as noted in the table of Figure 13K.

[0093]

[0125] Figure 13M depicts, according to various embodiments, a plot of stress and spring vertical height as a function of liner thickness that matches the table of Figure 13K. Plots 1360 - 1363 represent spring vertical heights of 0.5 inches (13 mm), 0.7 inches (18 mm), 0.9 inches (23 mm), and 1.1 inches (28 mm), respectively. For example, the ideal stress range is less than 186 ksi or 1,282 mPa. Generally, taller springs may be below the stress limit for any liner thickness. The sensitivity to liner thickness is approximately the same for all spring heights. However, as with the spring constant, considering the theoretically possible range, not all spring thicknesses / widths can be manufactured in a practical way. The spring width varies according to the spring thickness.

[0094]

[0126] Figure 14 shows liner designs of examples with different minimum bend radii, according to various embodiments. As described above, the softer (more gradual) bend points of the spring result in a smaller CLR at a similar stress, while the sharper (less gradual) bend points of the spring result in a smaller CLR but a higher stress. Liner design 1400 has a minimum bend radius (MBR) of 4 mm (0.16 inches) at bend point 1401, which is within the guideline of about 2 mm (0.08 inches) to about 5 mm (0.20 inches). Liner design 1410 has a relatively small or sharp minimum bend radius of 1.6 mm (0.06”) at bend point 1411, which is smaller than the guideline. In this design, there is a possibility of generating an overly high stress in the spring.

[0095]

[0127] Also, as described above, a larger vertical height significantly reduces the spring constant. However, if the bend radius is too flat, the spring constant can be increased. For example, liner design 1420 has a spring arm with a relatively high height, but the minimum bend radius is relatively large (16 mm or 0.63”) at bend point 1421, and as a result, the spring constant is advantageously relatively low. Liner design 1430 has a very large minimum bend radius (23 mm or 0.90”) at bend point 1431 and approaches flatness, so the spring constant increases disadvantageously.

[0096]

[0128] Liner designs 1440 and 1450 do not have a narrow bending radius but are still good designs. Liner designs 1440 and 1450 have minimum bending radii of 6.4 mm (0.25 inches) and 7.9 mm (0.31 inches) respectively at bending points 1441 and 1451. In some cases, a minimum bending radius of about 2 mm (0.08 inches) to about 8 mm (0.31 inches) can be used. A minimum bending radius of less than about 8 mm (0.31 inches), 10 mm or 12 mm can be used. In some cases, the minimum bending radius is in the range of about 2 mm (0.08 inches) to about 8 mm (0.31 inches), or in the range of about 2 mm (0.08 inches) to about 10 mm (0.39 inches). These ranges are for folding knives sized to fit the hands of the average user.

[0097]

[0129] For liner designs 1400, 1410, 1420, 1440, and 1450, the springs are shown at the lock load position and the maximum load position. For liner design 1430, the spring is shown at the lock load position.

[0098]

[0130] Figure 15 shows liner designs of examples with different starting angles according to various embodiments. This is one of the most important shape variables. A relatively large starting angle (OA) greater than 180 degrees, or at least greater than 90 degrees, is typically desired. A relatively large horizontal offset is also typically desired. The horizontal offset may be defined as the horizontal distance (along the longitudinal length of the knife handle) between the starting point of the spring and the shoe of the spring, and may be defined, for example, at the point where the shoe surface contacts the lock stud at the lock load position as scribed in Figure 12A.

[0099]

[0131] In the liner design 800 of FIG. 12A, it should be recalled that the starting angle is greater than 225 degrees. In the liner design 1510, the starting angle is smaller than that of the liner design 800, but still greater than 180 degrees. In the liner design 1520, the starting angle is the same as that of the liner design 1510. Furthermore, the horizontal offset is greater than the offsets in the liner design 800 and the liner design 1510. The liner design 1530 is smaller than the liner design 800, the liner design 1510, and the liner design 1520, but still has a starting angle greater than 180 degrees.

[0100]

[0132] At this point, several conclusions can be drawn. First, combining good vertical height, arc length, bend radius, and starting angle are all additively good. Second, a spring that has good characteristics at other points may be destroyed if one of the variables is poor. Third, the width and thickness of the lever arm material have a very strong influence on the spring constant. Fourth, the most important shape variables are the total vertical height and the total arc length. The next most important shape variables are the bend radius and the starting angle.

[0101]

[0133] FIG. 16 shows liner designs of examples according to various embodiments. The liner design 1600 has a J-shaped spring 1601 within the liner 1602, has good X-direction displacement, but has some Y-direction displacement. It occupies the smallest space and is the easiest to manufacture. In addition, the front region 1603 of the liner notch 1605 has a height that is slightly larger (e.g., up to 10 - 25% larger) than the diameter of the lock stud to guide the forward and backward movement of the lock stud. The spring 1601 is shown at the lock load position.

[0102]

[0134] When comparing the lock load position and the maximum load position of the spring, the X displacement represents the movement of the shoe in the x - direction or horizontal direction, and the Y displacement represents the movement of the shoe in the y - direction or vertical direction. Horizontal movement is desirable as it allows the lock stud to move rearward, while vertical movement is less desirable as, as described above, it allows the lock stud to snap back away from the top liner wall.

[0103]

[0135] Liner design 1610 has good X displacement and substantially no Y displacement. It occupies more space in the X - direction than liner design 1600. The spring is shown at lock load position 1611 and maximum load position 1612. The displacement of the shoe 1611a between the two positions is advantageously substantially restricted in the horizontal direction, which is the direction of movement of the lock stud. Further, there is no additional friction. However, this design requires a larger liner body and cutouts.

[0104]

[0136] Liner design 1620 has the largest X displacement and essentially no Y displacement compared to liner design 1600 and liner design 1610, but it is more difficult to manufacture and may occupy more space. The spring is shown at lock load position 1621 and maximum load position 1622. The spring has moved from the plane of the cutout at the maximum load position. The spring includes an additional bend 1623. The displacement of the shoe 1621a between the two positions is also essentially restricted in the horizontal direction.

[0105]

[0137] Liner design 1600 is more preferable than other designs due to its compact shape.

[0106]

[0138] Generally, as the height of the spring increases and the starting point within the liner decreases, advantageously, the horizontal displacement of the spring shoe increases and the vertical displacement decreases. In this case, the spring tends to hold the lock stud against the top wall of the liner to prevent a clicking sound.

[0107]

[0139] In addition, when the horizontal range of the spring is relatively large (as in liner design 1610 or liner design 1620 compared to liner design 1600), the shoe tends to move right and up when transitioning from the lock load position to the maximum load position. Also, the horizontal displacement of the shoe is relatively large and the spring constant is relatively small.

[0108]

[0140] Similarly, when the horizontal range of the spring is relatively small (e.g., liner design 1600 compared to liner design 1610 and liner design 1620), the shoe tends to move right and down when transitioning from the lock load position to the maximum load position. Also, the horizontal displacement of the shoe is relatively small and the spring constant is relatively large.

[0109]

[0141] FIG. 17 shows liner designs of examples where efficiency varies according to various embodiments. This includes lessons learned regarding stress balance. Generally, by dispersing stress over more bends and a longer distance within the spring, the x-displacement can be increased without increasing stress, and a lower spring constant can be obtained. Liner design 1700 and liner design 1710 exhibit relatively low efficiency because the number of bends and the length of the spring are relatively low. Liner design 1720 and liner design 1730 exhibit intermediate efficiency because the number of bends and the length of the spring are intermediate between relatively low and relatively high. Liner design 1740 and liner design 1750 exhibit relatively high efficiency because the number of bends and the length of the spring are relatively high. However, the effectiveness of the spring also depends on the origin and the total horizontal width of the spring.

[0110]

[0142] Some non-limiting examples of various embodiments are shown below.

[0111]

[0143] Example 1 includes a knife comprising a blade and a handle attached to the blade, the blade being rotatable about a pivot point within the handle, the handle comprising a slot in which a lock stud moves in forward and rearward directions, a liner, and a curved elongate spring extending from the liner at a starting point to a free end and having a shoe at the free end for biasing the lock stud in the forward direction.

[0112]

[0144] Example 2 includes the knife of Example 1, the curved elongate spring being vertically oriented and having a height greater than the overall horizontal width.

[0113]

[0145] Example 3 includes the knife of Example 1 or Example 2, the lock stud being in contact with a tang of the blade, the tang having a flat surface against which the lock stud contacts to lock the blade in the open position when the blade is in the open position, and a rounded surface against which the lock stud contacts to enable the blade to move between the open position and the closed position when the blade moves between the open position and the closed position.

[0114]

[0146] Example 4 includes the knife of any one of Examples 1 to 3, the curved elongate spring having a spring constant of 3 to 15 pounds per inch (525 to 2626 N / m), 2 to 25 pounds per inch (350 to 4378 N / m), or 5 to 20 pounds per inch (875 to 3502 N / m).

[0115]

[0147] Example 5 includes the knife of any one of Examples 1 to 4, the ratio of the vertical height of the curved elongate spring to the vertical height of the liner being at least 0.4 or 0.5.

[0116]

[0148] Example 6 includes the knife of any one of Examples 1 to 5, the ratio of the arc length of the curved elongate spring to the vertical height of the liner being at least 0.5 or 0.6.

[0117]

[0149] Example 7 includes any one of the knives of Examples 1 to 6, and the curved elongated spring is formed integrally with the liner.

[0118]

[0150] Example 8 includes any one of the knives of Examples 1 to 7, and the curved elongated spring is a separate part attached to the liner.

[0119]

[0151] Example 9 includes any one of the knives of Examples 1 to 8, and the starting point is in front of and below the shoe.

[0120]

[0152] Example 10 includes any one of the knives of Examples 1 to 9, and the shoe has a flat surface that engages with the lock stud.

[0121]

[0153] Example 11 includes any one of the knives of Examples 1 to 10, and the rear side of the shoe includes a protruding stopper.

[0122]

[0154] Example 12 includes any one of the knives of Examples 1 to 11, where the liner is the first liner of the knife, the knife further includes a second liner, the first liner and the second liner are on opposite sides of the tang of the blade, and the second liner includes a curved elongated spring that biases the lock stud in the forward direction.

[0123]

[0155] Example 13 includes any one of the knives of Examples 1 to 12, and the curved elongated spring is J-shaped.

[0124]

[0156] Example 14 includes a liner for a knife, and includes a main body with sheet metal, and a curved elongated spring that extends within the notch region of the main body, starts at the starting point, and extends to the shoe at the free end of the elongated spring.

[0125]

[0157] Example 15 includes the liner of Example 14, and the shoe biases the lock stud of the knife in the forward direction of the knife.

[0126]

[0158] Example 16 includes the liner of Example 14 or Example 15, and the curved elongated spring is formed from sheet metal integral with the body.

[0127]

[0159] Example 17 includes the liner of any one of Examples 14 to 16, and the curved elongated spring is a separate part attached to the body.

[0128]

[0160] Example 18 includes the liner of any one of Examples 14 to 17, and the curved elongated spring has a minimum bending radius in the range of about 2 mm (0.08”) to about 10 mm (0.39”).

[0129]

[0161] Example 19 includes the liner of any one of Examples 14 to 18, and the curved elongated spring is J-shaped.

[0130]

[0162] Example 20 includes the liner of any one of Examples 14 to 19, and the starting point is in front of and below the shoe.

[0131]

[0163] Example 21 includes the liner of any one of Examples 14 to 20, and the curved elongated spring has a spring constant of about 3 - 15 pounds per inch (525 - 2626 N / m), 2 - 25 pounds per inch (350 - 4378 N / m), or 5 - 20 pounds per inch (875 - 3502 N / m).

[0132]

[0164] Example 22 includes the liner of any one of Examples 14 to 21, and the ratio of the vertical height of the curved elongated spring to the vertical height of the liner is at least 0.4 or 0.5, and the ratio of the arc length of the curved elongated spring to the vertical height of the liner is at least 0.5 or 0.6.

[0133]

[0165] Example 23 includes the liner of any one of Examples 14 to 22, and the curved elongated spring is vertically oriented and has a height greater than the total horizontal width.

[0134]

[0166] Example 24 includes a knife comprising a blade and a handle attached to the blade, the blade being rotatable about a pivot point within the handle, the handle comprising a first liner and a second liner spaced apart from each other, each liner comprising a slot for a lock stud, each liner comprising a curved elongated spring, and for each liner, the curved elongated spring extending from the liner at a starting point to a free end, the free end comprising a shoe for biasing the lock stud in a forward direction to lock the blade in an open position, the first liner and the second liner.

[0135]

[0167] Example 25 includes the knife of Example 24, and for each respective liner, the curved elongated spring is vertically oriented and has a height greater than the overall horizontal width.

[0136]

[0168] Example 26 includes the knife of Example 24 or Example 25, and the curved elongated spring is integrally formed with the liner.

[0137]

[0169] Example 27 includes the knife of any one of Examples 24 to 26, and the curved elongated spring is a separate part attached to the liner.

[0138]

[0170] Example 28 includes the knife of any one of Examples 24 to 27, and the starting point is in front of and below the shoe.

[0139]

[0171] Example 29 includes the knife of any one of Examples 24 to 28, and the shoe has a flat surface that engages with the lock stud.

[0140]

[0172] Example 30 includes the knife of any one of Examples 24 to 29, and the curved elongated spring is J-shaped.

[0141]

[0173] While specific embodiments have been illustrated and described herein, it will be understood by those skilled in the art that various alternative and / or equivalent embodiments or implementations calculated to achieve the same purpose may be used instead of the embodiments illustrated and described without departing from the scope. Those skilled in the art will readily understand that the embodiments can be implemented in a very wide variety of ways.

[0142]

[0174] This application is intended to cover any adaptations or variations of the embodiments discussed herein. Accordingly, it is expressly intended that the embodiments be limited only by the claims and their equivalents.

Claims

1. A knife comprising a blade and a handle, wherein the handle is attached to the blade, the blade is rotatable about a pivot point within the handle, and the handle comprises a slot in which a lock stud moves in a front - rear direction, a liner, a curved and elongated spring, and wherein the curved and elongated spring extends from the liner at a starting point to a free end, and the free end comprises a shoe that biases the lock stud in a forward direction. A knife.

2. The knife according to claim 1, wherein the curved and elongated spring is oriented vertically and has a height greater than the overall horizontal width.

3. The lock stud is in contact with a tang of the blade, and the tang comprises a flat surface with which the lock stud contacts to lock the blade in the open position when the blade is in the open position, and a rounded surface with which the lock stud contacts to enable the blade to move between the open position and the closed position when the blade moves between the open position and the closed position. The knife according to claim 1 or 2.

4. The knife according to any one of claims 1 - 3, wherein the curved and elongated spring has a spring constant of 3 - 15 pounds per inch (525 - 2626 N / m), 2 - 25 pounds per inch (350 - 4378 N / m), or 5 - 20 pounds per inch (875 - 3502 N / m).

5. The knife according to any one of claims 1 - 4, wherein the ratio of the vertical height of the curved and elongated spring to the vertical height of the liner is at least 0.4 or 0.

5.

6. The knife according to any one of claims 1 - 5, wherein the ratio of the arc length of the curved and elongated spring to the vertical height of the liner is at least 0.5 or 0.

6.

7. The knife according to any one of claims 1 - 6, wherein the curved and elongated spring is integrally formed with the liner.

8. The knife according to any one of claims 1 - 7, wherein the curved and elongated spring is a separate part attached to the liner.

9. The knife according to any one of claims 1 - 8, wherein the starting point is in front of and below the shoe.

10. The knife according to any one of claims 1 - 9, wherein the shoe has a flat surface that engages with the lock stud.

11. The knife according to any one of claims 1 to 10, wherein a rear side of the shoe is provided with a protruding stopper.

12. The liner is a first liner of the knife, the knife further includes a second liner, the first liner and the second liner are on opposite side portions of the tang of the blade, and the second liner includes a curved and elongated spring that biases the lock stud in a forward direction. The knife according to any one of claims 1 to 11.

13. The curved and elongated spring is J-shaped. The knife according to any one of claims 1 to 12.

14. In a liner for a knife, a main body including sheet metal, a curved and elongated spring extending within a notch region of the main body, and the elongated spring starts at a starting point and extends to the shoe at a free end of the elongated spring. A liner.

15. The shoe biases the lock stud of the knife in a forward direction of the knife. The liner according to claim 14.

16. The curved and elongated spring is formed from the sheet metal integral with the main body. The liner according to claim 14 or 15.

17. The curved and elongated spring is a separate component attached to the main body. The liner according to any one of claims 14 to 16.

18. The curved and elongated spring has a minimum bending radius in the range of about 2 mm (0.08") to about 10 mm (0.39"). The liner according to any one of claims 14 to 17.

19. The curved and elongated spring is J-shaped. The liner according to any one of claims 14 to 18.

20. The starting point is in front of and below the shoe. The liner according to any one of claims 14 to 19.

Images