EP3835708B1 - Front shaft for clamping on an existing weapon - Google Patents

Description

The invention relates to a fore-end for clamping mounting on a firearm, in particular a rifle (carbine), also referred to in simple terms as fore-end clamping or just clamping, especially for weapons of the M4/M16/AR15 rifle type, according to the preamble of claim 1 and the WO 2013/010516 A1 . The clamping device according to the invention and its variants are not limited to rifles, carbines, etc., but can in principle also be used for pistols. The improvements and their effects/benefits are listed below.

From the WO 2013/010516 A1 a forend is known in which a lever arm and a clamping cone interact with a conical, slotted clamping surface of the stock housing in order to achieve the clamping fixation. The seat achieved is not defined in more detail when viewed in the axial direction.

For many rifles (carbines), especially those of the types mentioned, fore-stocks have been known as independent parts for many years and are commercially available and fulfill a wide variety of requirements. It is therefore assumed in the following and in the claims of the carbine that the invention relates to a fore-end adapted to the carbine, which therefore fits geometrically and functionally to the weapon so that it can be used with the fore-end according to the invention. As a general technological background one can briefly state the following:
On the one hand, forends form a grip area for the shooter's free hand - the aiming hand - and serve as protection against burns from the hot barrel. On the other hand, a forend protects the barrel from impacts, dirt, etc. and can be used as a holder for a variety of accessories, such as rifle scopes, low-light amplifiers, flashlights, laser pointers, and much more.

The forend can be understood as a kind of extension of the housing of a rifle in the direction of the barrel. In order to improve the precision of a rifle, the forend must be connected to the housing as rigidly as possible relative to the barrel and therefore also relative to the housing. However, the barrel must be able to swing “freely” when the shot is fired.

The barrel is usually attached to the housing using a barrel nut, which is usually designed as a union nut and is screwed to the housing. The barrel nut presses the barrel against a radially projecting shoulder of the housing.

From the prior art, a variety of options are known for AR-15 type rifles to couple a forend to the housing, very often involving a clamping in the circumferential direction, i.e. tangential to the stock axis, which is described below when taken out of context nothing else results, even if the term “axial direction” is used, the reference axis. In most cases, tensioning against the running direction, i.e. against the upper housing, is achieved by means of a separate, second clamping device.

There remains a desire for quick disassembly/assembly of the forend, whether in use or for maintenance purposes. Furthermore, the disassembly or assembly process should be able to be carried out as simply as possible. Special tools are often required, which of course have to be carried separately. The tangential clamping is often done using screws that clamp the forend tangentially to the barrel nut, as shown in the example US 9,032,658 B2 shown. There, there is additional protection against displacement of the forend in the axial direction by the screws partially engaging in the grooves provided in the barrel nut.

The follows a similar approach US 7,5228,580 B1 , which prevents the forend from shifting in the axial direction by a tangentially movable locking pin.

As a rule, a plurality of components are required to form a clamping at least in the tangential direction. Securing and pre-tensioning the barrel in the axial direction, preferably also via a clamp, would also be desirable in order to form the most rigid connection possible between the housing and forend.

The object of the present invention is therefore to provide a clamping device which secures the forend against displacement relative to the housing and at the same time ensures a rigid connection to the housing. A further object of the invention is that the smallest possible number of components is used for the clamping device. A further object of the invention is to provide a clamping device that is easy to handle, easy to maintain and has a relatively simple structure.

This task is solved by the features specified in claim 1.

In the description and the claims it is used "in front" or "(to) the front" as the direction towards the muzzle of the barrel, "(to) the rear" as the direction towards the stock, "(to) the bottom" as the direction for the breech towards the magazine, and "(up)" used as the direction away from the magazine. The terms "weapon midlevel", "running soul", "running axis", "soul axis", etc. have the usual meaning that the person skilled in the art attaches to them in the prior art. “Left” is therefore related to the center plane of the weapon, “from the left” corresponds to a movement, actuation, exertion of force in the direction of the center plane of the weapon, starting from an initial position “to the left” of it, etc. The breech moves under the effect of the gases When a shot is fired, it moves “backward” and then moves “forward” again under the action of a recoil spring, etc.

• die Fig. 1 eine schematische Explosionsdarstellung eines Vorderschafts,
• die Fig. 2 den Schnitt II-II der Fig. 1,
• die Figs. 3a,b den Schnitt III-III der Fig. 1 in zwei unterschiedlichen Klemmsituationen,
• die Figs. 4a,b einen Hebel in zwei unterschiedlichen perspektivischen Ansichten,
• die Figs. 5a-c eine Mutter in unterschiedlichen Ansichten,
• die Figs. 6a,b ein Detail am Vorderschaft in unterschiedlichen Ansichten und
• die Figs. 7a-c unterschiedliche Klemmsituationen in einem axialen Schnitt.

The invention is explained in more detail below with reference to the drawings. This shows or shows:

• the Fig. 1 a schematic exploded view of a forend,
• the Fig. 2 the section II-II of the Fig. 1 ,
• the Figs. 3a,b the section III-III of the Fig. 1 in two different clamping situations,
• the Figs. 4a,b a lever in two different perspective views,
• the Figs. 5a-c a mother with different views,
• the Figs. 6a,b a detail on the forend in different views and
• the Figs. 7a-c different clamping situations in an axial section.

In the figures, everything that concerns the forend 1 without the clamping device was labeled "1n", and similarly everything that concerns the clamping device 2 was labeled "2n".

In the Figs. 1-6 Examples of embodiments are shown that are suitable for use in an AR15 or M4 rifle. Modifications of the examples shown can be easily and simply transferred to other types of rifles by a person skilled in the art with knowledge of the invention and without extensive or complex experiments.

The Fig. 1 shows a schematic exploded view of a forend 1 with housing 11 and built-in spacer 12, which is not essential to the invention and is therefore not explained further. Also shown is a clamping device 2 according to the invention with a lever 21, a nut 28 and a locking ring 281; a coordinate system used variously in the description and the claims 51-running direction, shaft direction, forward; 52-transverse direction to the left and 53-vertical direction upwards are entered for better orientation.

The Fig. 2 shows section II-II of the Fig. 1 , an axial section through the shaft axis 41, thus parallel to the barrel axis. The barrel 15 is radially closest to the barrel axis (parallel or coinciding with the shaft axis 41), a barrel nut 13 in the form of an elongated sleeve is optionally pushed onto it and connected to the upper housing 14 at its rear end by means of a screw connection 42. This means that a collar of the barrel 15 is pressed by a rear end face of the barrel nut 13 against a front end face of the upper housing 14 and the barrel 15 itself is held in place. The housing 11 of the forend 1 not only encloses the barrel 15 including the barrel nut 13, but also a gas pipe 16.

An annular groove 131 is provided in the running nut 13, the lever 21 lies partly in this annular groove and is cut in the area of its middle piece 26 in this illustration. In the housing 11 there is an elongated hole running in the transverse direction 52 provided, the cross section of which has circular end sections two mutually parallel elongated hole axes 191, 192 running in the transverse direction 52. These axes lie in a plane normal to the vertical 52.

The Figs. 3a ,b are a section along line III-III of the Fig. 1 , thus normal to the shaft axis 41, and represent two different clamping situations.

The structure itself is as follows: The lever 21 is pushed with its threaded end first through the elongated hole 19, the nut 28 with its cone 282 is directed towards the weapon, screwed on and secured against loss by means of the resilient locking ring 281. By screwing on the nut 28, a longitudinal slot 17 in the housing 11 or the spacer 12 in the area of the lever 21 is changed in width and, together with the conical sections 22 of the shaft and 282 of the nut, ensures pretension and adjustment.

• der Ringnut 131 der Laufmutter 13,
• des Langloches 19 des Gehäuses 11 und
• des Schaftes des Hebels 21

das Gehäuse 11 in Richtung 51 der Schaftachse 41 zum Obergehäuse 14 hin gezogen und durch das (vorherige oder weitere) Anziehen der Mutter 28 mit verengendem Schlitz 17 eine zunehmende Klemmung in Umfangsrichtung - also tangential zum Lauf 15 - bewirkt.The Fig. 3a shows the released position in which the recess 23 is directed towards the shaft axis 41 and allows a longitudinal movement of the housing 11 along the barrel and the barrel nut 128 (if the nut 28 is not screwed on too tightly), since the contour in the area of the recess 228 lies radially outside the contour of the running nut. If the rear end position ( Fig. 2 ) is reached, if necessary after tightening the nut 28, the lever arm 27 is rotated by 180 ° about the lever axis 291, whereby the shaft with its non-tapered surface area enters the annular groove 1281. The positions and geometries:

• the annular groove 131 of the running nut 13,
• the elongated hole 19 of the housing 11 and
• the shaft of the lever 21

the housing 11 is pulled in the direction 51 of the shaft axis 41 towards the upper housing 14 and the (previous or further) tightening of the nut 28 with a narrowing slot 17 causes an increasing clamping in the circumferential direction - i.e. tangential to the barrel 15.

The ones in the Figs. 4a ,b Clamping device 2 shown in detail consists of a lever 21 with a shaft with a lever axis 291, in one end region of which a thread 24 is provided, and at the other end of which a lever arm 27 projects approximately at a right angle. In this end region, the diameter of the shaft increases conically towards the lever arm 27 and forms a clamping cone 22. The shaft has a recess 23 on the middle piece 26, approximately in the middle, which forms a generally cylindrical, preferably circular-cylindrical, lateral surface; in the exemplary embodiment, the generatrixes of the lateral surface run parallel to the plane defined by the lever axis and the lever arm 27. It can also be seen from these figures that the thread 24 does not extend to the end of the shaft, but ends at an annular groove 25 whose inner diameter is smaller than the diameter of the thread base. The shaft diameter in the immediate end area is larger than that of the groove, but smaller than that of the thread base.

A nut 28 interacts with the thread 24 of the shaft and is in the Figs. 5a -c is shown. This nut 28 is provided in a first axial region with an internal thread that can cooperate with the thread 24; in a second axial region it has a cylindrical bore (recess) with a larger diameter than the shaft diameter. This recess runs over the entire remaining length (actually height) of the nut 28. In the first axial region, the outer contour of the nut is cylindrical with a subsequent conical taper towards the end, and in the second, an external hexagon is provided.

By turning the lever arm 27 in the installation position (see Figs. 3 and 7 ) is secured against axial displacement by the middle piece 26 in cooperation with the annular groove 131 of the forend 1. A special feature is the design of the clamping cone 22 on the shaft of the lever 21 and the clamping cone 282 on the nut 28 in conjunction with the two corresponding clamping surfaces 18 of the forend 1. This double-conical design results in a self-centering clamping when the nut 28 is tightened after moving lever 2 to the locking position.

An aspect of the invention that is also important in one embodiment lies in the design of the in the Figs. 6a ,b elongated hole 19 shown in more detail, which, as already mentioned, has two elongated hole axes 191, 192 running parallel to one another. In addition, there is the preferably concentric conical clamping surface 18 (on both sides of the forearm 1) centered around the axis 191, which results in a displacement and/or application of force to the forend against the direction of travel when a tangential force is applied around the lever axis 291 , towards the upper housing 14, which enables axial fixation and thus fixation in addition to tangential fixation.

The assembly is carried out with the lever 21 in the "OPEN" position until it stops on the "Upper", then the nut 28 is tightened, narrowing the gap 17 and thus fixing the housing 5 to the running nut 128. This situation is essentially in Figs.7a -c shown. The first elongated hole axis 191 is further away from the upper housing 14 than the second elongated hole axis 192.

In Fig. 7a the housing 11 with the clamping device 2 is placed in the "OPEN" position, the lever axis 291 is at a distance from the second elongated hole axis 192 and is closer to the upper housing than this.

The Fig. 7b shows the situation when turning the lever 21 into the "LOCKED" position, the two axes have become much closer to each other and can also coincide.

The Fig. 7c shows the situation after tightening the clamping nut 28, since the clamping surface 18, which is conical around the axis 191, as the arrow indicates, causes a load/displacement of the housing 11 of the forend 1 in the direction of the upper housing 14, thus stable mechanical conditions prevail .

The invention thus enables tangential and axial clamping of the forend at the same time.

In the illustrated embodiment, the outer diameter of the nut 28 is selected such that a part of the weapon, preferably the slider (not shown), can be used to loosen the nut 28. This means that the slider 28 with its slot-shaped opening, which allows the hammer or striker to pass through, can be used to screw on or unscrew the nut 28. A “half-inch” width of the nut head is therefore particularly preferred.

Further refinements relate to the already explained protection against loss of the clamping device through the annular groove 25 on the lever 21 in conjunction with the locking ring 281, which prevents the nut from being completely unscrewed and thus from being lost.

It is clear to the person skilled in the art that the illustrated and described embodiments are to be viewed as exemplary; knowing the invention, he can easily transfer and adapt them to other weapons. The materials to be used are the same as in the prior art, as is the processing and the manufacturing processes to be chosen.

In the description and claims, the terms "front", "rear", "top", "bottom" and so on are used in the common form and with reference to the article in its usual position of use. This means that in a weapon the muzzle of the barrel is "front", that the breech or slide is moved "backwards" by the explosion gases, etc. Transverse to a direction essentially means a direction rotated by 90° to it, Unless otherwise stated, special reference is made to the coordinate system 51 - running direction, 52 - transverse direction and 53 - vertical (with the usual position of the weapon at the ready), which are drawn and described variously in the figures, for better orientation.

It should also be pointed out that in the description and the claims, information such as "lower area" of an object means the lower half and in particular the lower quarter of the total height, and "lowest area" means the lowest quarter and especially an even smaller part; while "middle area" means the middle third of the total height (width - length). All of this information has its common meaning, applied to the intended position of the item under consideration, unless otherwise stated.

In the description and claims, "substantially" means a deviation of up to 10% of the specified value, if physically possible, both downwards and upwards, otherwise only in the sensible direction, for degrees (angle and temperature) This means ± 10°.

All quantities and proportions, in particular those defining the invention, as long as they do not relate to the specific examples, are to be understood with a tolerance of ± 10%, so for example: 11% means: from 9.9% to 12.1%. In terms such as: "a solvent", the word "a" is not to be viewed as a numeral, but rather as an indefinite article or as a pronoun, unless the context indicates otherwise.

The term: "combination" or "combinations" stands, unless otherwise stated, for all types of combinations, starting from two of the components in question up to a large number or all of such components; the term: "containing" also stands for "existing out of".

The features and variants specified in the individual embodiments and examples can be freely combined with those of the other examples and embodiments and can be used in particular to characterize the invention in the claims without necessarily including the other details of the respective embodiment or example

To make the invention easier to understand, the English terms, which can also be used as synonyms, are given in the following list of reference symbols. 1 forestock 41 Stock axis 11 Forend housing (handguard) 42 screw connection (joint) 12 Spacer 13 barrel nut 51 barrel direction 131 (barrel nut channel) 52 Transverse direction (normal direction) 14 Upper receiver 53 Vertical direction 15 barrel 16 gas pipe 17 slot 18 Clamp taper surface 19 long hole 191 First long hole axis (Is long hole axis) 192 second long hole axis 2 Clamping device 21 lever 22 clamp taper socket 23 recess 24 thread 25 Ring groove (ring recess) 26 Middle piece (center element) 27 lever arm 291 Lever axis 28 mother (nut) 281 Circlip (safety ring) 282 clamp taper socket

Claims (2)

1. Handguard for clamping mounting on an existing firearm, in particular on its barrel (15) or its barrel nut (13), the barrel (15) or the barrel nut (13) having an annular groove (281), comprising:

   - a shaft housing (11) with a shaft axis (41), which has a slit (17) running radially thereto and a through-opening running in the transverse direction (52) for a clamping device,

   - a clamping device (2) for the shaft housing (11), comprising

   ∘ a lever (21) having a center element (26) which surrounds the lever axis (291) and lies in a through-opening of the shaft housing (11) in a normal plane with respect to the shaft axis (41), and which has a recess (23) in its center area, a thread (24) at one end portion and a lever arm (27) at the other end, and

   ∘ a nut (28) with an internal thread matching the thread (24);

   whereby the center element (26) is provided at its end portion directed towards the lever arm (27) with a clamp taper socket (22) widening towards the lever arm (27) and contacts a conical clamping surface (18) of the shaft housing (11);

   whereby, in the assembled state, the nut (28) is screwed onto the thread (24) and thus narrows the slit (17), and the angular position of the lever (21) about its lever axis (291) is such that its center element (26) contacts the annular groove (281),

   characterized in that, the nut (28) is provided on its outer side with a conical area, a clamp taper socket (282), in that, in the shaft housing (11), the through-opening for receiving the center element (26) is a long hole (19) with an outline comprised of two semicircles with a first axis (191) and a second axis (192) parallel thereto and a rectangle located in-between, and in that the long hole (19) is provided on both ends with conical clamp surfaces (18), which are centric around the first axis (191) and co-operate with the clamp taper sockets (22, 282).
2. Handguard according to claim 1, characterized in that the center element (26) is provided with an annular groove (25) at its end portion having the thread (24), and in that the nut (28) has the internal thread in a first axial section, and in that a bore with a larger diameter is formed in a second axial section, and in that a safety ring (31) is inserted into the annular groove (25).

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