WO2004055466A1

WO2004055466A1 - Method and device for aligning sight and barrel

Info

Publication number: WO2004055466A1
Application number: PCT/SE2003/001870
Authority: WO
Inventors: Anders Malmgren
Original assignee: Saab Ab
Priority date: 2002-12-17
Filing date: 2003-12-09
Publication date: 2004-07-01
Also published as: EP1616145A1; AU2003289689A1; SE524435C2; SE0203721L

Abstract

The present invention relates to a method and an arrangement for use with a barrelled weapon for aligning the centre line of the barrel (2) with the weapon’s sight (3). The invention is primarily intended to be used with such barrelled weapons (2) as are mounted on a gun carrier 81), such as a tank or the like, and which have a sight (3) that is mounted separately on the gun carrier (1). The invention is characterized in that, during aligning, an image-generating sensor (9) is used as reference for the centre line of the barrel, which image-generating sensor is moved forward through the barrel from its breech to a position immediately inside its muzzle, and which image-generating sensor has its line of vision along the direction of fire of the barrel.

Description

METHOD AND DEVICE FOR ALIGNING SIGHT AND BARREL

The present invention relates to a method and an arrangement for use with a barrelled weapon for aligning the centre line of the barrel with the weapon's sight. The invention is primarily intended to be used with such barrelled weapons as are mounted on a gun carrier such as a tank or the like, with a sight in the form of cross-hairs, a reticule plate or the like, which is mounted separately on the gun carrier. The method and arrangement are suitable for direct-shooting medium-calibre and large-calibre barrelled weapons. By medium-calibre and large-calibre barrelled weapons is meant here weapons with a calibre of 20 mm and upwards.

Special advantages of the invention are that it makes it possible to align the outer part of the barrel's centre line with the sight and that this aligning operation can be carried out completely from the interior of the gun carrier. In the case when the gun carrier consists of a tank, the alignment can be carried out without any of the crew needing to leave the protective interior of the tank, while at the same time the aligning operation itself can be carried out completely by a single man, preferably the gunner himself .

For alignment of the barrel and the sight in direct- shooting weapons, it is particularly important that the aligning operation is actually based on the outer part of the centre line of the barrel. K ^"large number of test shots under carefully controlled conditions have shown that it is the alignment of the centre line furthest out towards the muzzle of the barrel that primarily determines where a projectile fired through the barrel strikes. By furthest out towards the muzzle of the barrel is meant here a length corresponding to 3-4 times the calibre of the weapon.

The need to align the barrel and the sight is not something that can be carried out once and for all, but is a continually recurring need, as differential heating or cooling of the barrel produces barrel distortions, while both the sight and the barrel bearings are affected by mechanical imperfections that can become apparent when the gun carrier moves through the terrain. For the crew of, for example, a tank, it can thus be a question of having to check the alignment between the barrel and the gun sight frequently.

Currently, the most common method of aligning the centre line of the barrel with the cross-hairs sight of the gun is by the use of a so-called muzzle reference telescope. This method requires, however, the loader or someone else in the vehicle to leave the relative safety of the vehicle during the actual aligning operation, which can put his life in danger in critical situations. In addition, the use of the muzzle reference telescope is based on the gunner and the loader working together during the aligning operation and giving each other directions until the weapon' s centre line and the sight line coincide at a previously selected distant object. Such an aligning operation takes a long time.

Another method for aligning barrel and sight is described in US 4,879,814. The method described therein is based on a laser pointer being placed in the chamber of the barrel, which is thus carried out from inside the tank itself. This method has, however, the disadvantage that the alignment carried out in this way is based upon the centre line of the chamber and not the alignment of the centre line of the barrel at the actual muzzle of the barrel which is more important for the strike point.

Another known method for alignment of barrel and sight is described in US 4,676,636, but here a mirror is used which is placed above the barrel, and which reflects a beam of light, from a light source arranged on the gun carrier, back to a mirror sight similarly arranged on the gun carrier. Thus the position on the outside of the barrel muzzle is principally checked here, and only indirectly the alignment of the centre line. It is thus necessary also to have a muzzle reference telescope or alternatively an arrangement according to the present invention in order to carry out the alignment of the inside of the barrel muzzle. This known method is expensive to realize, particularly for existing barrels. The mirror is, for example, di-fficult to attach to the' barrel if the calibre is large. In addition, the arrangement for positioning the mirror is relatively complicated.

The present invention has the task of presenting a new method and a new arrangement for aligning the centre line of the barrelled weapon concerned with the weapon's sight which is preferably mounted separately on the gun carrier. As has already been mentioned by way of introduction, the great advantage of the invention is that the whole aligning operation can be carried out from the inside of the gun carrier and, in principle, by only one man, even though for practical reasons it can be expedient for the loader to put the arrangement according to the invention in place in the barrel, while the rest of the aligning operation is carried out byXhe gunner.

The basic principle for the invention is that an alignment marker is used as reference for the alignment of the barrel's centre line in the outer part of the centre line, which alignment marker is moved forward through the barrel from its breech to its muzzle and consists of an image-generating sensor, such as a video camera or IR camera, with its line of vision along the direction of fire of the barrel, which has the barrel's centre line within its field of vision and which, during the aligning operation, is fixed and preliminarily centred by means of, for example, self- centring clamps or the like.

According to a development of the invention, there is absolutely no need for the axis of the sensor to coincide completely with the barrel-' s centre line .

^• According to this variant, the sensor must be able to be rotated around its own line of vision inside the sensor carrier. This variant makes it possible, after the sensor carrier has been fixed in the barrel, to rotate the sensor inside the carrier and thereby ascertain the position of the point within the sensor' s image that does not move during the rotation. As this point indicates the position of the centre line, this is used as the initial position during the continued aligning operation.

Self-centring clamps arranged at the front and back ends of the sensor carrier are preferably used to attach it in the intended position in the barrel.

As the sensor and the sensor carrier with clamps can be made light, no complicated arrangements are required to move the sensor carrier forward through the barrel from the breech to the muzzle. As means of propulsion can be used, for example, a steel band that can be rolled up, a pantograph, a telescopic rod device or tubes that can be slotted into each other, stored in the tank close to the breech. All that is necessary is that the means of propulsion has sufficient rigidity to push the sensor carrier forward to the intended position in the muzzle of the barrel. In order to return the sensor carrier to the breech, the sensor' s video cable and operating cable for eccentric and turning functions can, for example, be used.

The invention has been defined in the following claims and will now be described in only slightly greater detail in association with the attached drawings.

These show: in Figure 1, a tank during alignment of sight and barrel, in Figure 2 , a longitudinal section through the front part of the tank' s gun barrel with the arrangement for alignment according to the invention shown in its moved-forward position, in Figure 3, in larger scale, a cross-section of the part of the barrel from Figure 2, in Figure 4, a longitudinal section through the arrangement according to the invention, and schematically in Figures 5-8, the alignment procedure according to the invention, step by step, with image a referring to the barrel part, while image b refers to the sight pa t.

The tank 1 shown in Figure 1 has a vehicle-mounted direct-shooting canon 2 and a sight 3 mounted separately on the vehicle. When aligned, the sight line 4 of the sight is to coincide at the target 5 with the linear extension of the barrel's centre line 6 in the outer part of the barrel towards its muzzle. During the aligning operation, an arrangement 7 according to the invention ^■ is clamped inside the front part 2a of the barrel 2 shown^{" "}in^" Figure 2. The ^"arrangement 7, which has been moved to this position from the barrel's breech inside the vehicle 1, comprises an^' outer casing 8, matched to the calibre of the barrel 2, which is clamped in the front part of the barrel, inside which outer casing 8 is mounted, in this example, a sighting marker 9 in the form of a video camera with its line of vision along the centre line of the barrel. Figure 1 shows that the centre line 6 is not parallel to the sight line . The angle between the centre line and the sight line depends upon the distance between the tank 1 and the alignment target 5. During the alignment procedure, the fire control system can compensate for the abovementioned parallax error. In order to carry this out, it is necessary to obtain the distance to the alignment target 5. A firing control system often comprises a laser range finder that can be used for this purpose.

For other components in the arrangement 7, refer to Figures 3 and 4. The outer casing 8 matched to the calibre of the barrel 2 is thus provided with self- centring locking devices 10 at its front and back ends for fixing the arrangement 7 inside the barrel 2. The locking devices 10 consist, in the example shown, of locking balls 11 which upon command can be forced out towards the inside of the barrel 2 by two conical clamping sleeves 12 and 13 which can be moved apart. The number of locking balls can vary from design to design, but in the case of the arrangement 7 being used in a rifled barrel, it is expedient to increase the number of balls. The clamping sleeves can be moved apart in the directions of the arrows a and b by an eccentric not shown in Figure 4, which eccentric is operated via a cable from the breech of the barrel. The clamping sleeves 12 and 13 are, as shown in Figure 4, arranged inside the outer casing 8. In addition, an internal supporting sleeve 14 is arranged on the inside of the clamping sleeves. This^" is mounted in the outer casing 8 via ball-bearings 15 and 16 in such a way that it can be rotated, and the abovementioned video camera 9 is attached inside the same. The video camera 9 is adjusted in such a way that its field of vision, when the arrangement 7 is mounted in the muzzle 2a of the barrel, includes the extension of the barrel's centre line from the part of the barrel in which the arrangement 7 is clamped. The fixing of the video camera 9 in the supporting sleeve 14 has the designation 17. The video camera 9 is connected via the cable 18 to a display 21 arranged inside the tank 2. The need to be able to rotate the video camera inside the outer casing 8 is explained in greater detail below.

The following alignment method that is described is given as an example of how this can be carried out. Figure 5a shows an example of how an image can appear initially in the display 21 connected to the video camera 9. A marker 22, for example cross-hairs or a reticule plate, shows the alignment of the video camera. The marker can be generated in the display 21 or in the video camera 9. For moving the marker 22 across the display 21, two potentiometers 24 and 25 are indicated schematically, by means of which the position of the marker 22 can be adjusted vertically and horizontally respectively. The target that is used for the alignment has the designation 5 and is illustrated here, as a triangle. In Figure 5a, the marker 22 and the alignment target 5 are separated. This also applies for corresponding elements in the sight image shown in Figure 5b, where the alignment target similarly has the designation 5, while the sight's cross-hairs or reticule plate is designated by 23. By rotating the camera 9 and studying the image on the display 21, a point 26 can be identified around which the image rotates. When the camera is rotated, the alignment target 5 in the image rotates with a constant radius around the sought point 26. The identified point corresponds to the centre line 6 of. the barrel. The point is marked in Figures 5a-8a and has the designation 26. Note, however, that the point can not be inserted in the image without additional steps being taken, but is a point identified by means of the observer's visual impression.

When the point 26 has been identified, the marker 22 is made to mark the point 26 by adjustment of the potentiometers 24 and 25. The new position of the marker, is shown in Figure 6a. The sight image shown in Figure 6b is unchanged in comparison with Figure 5b.

During the next step, the sight is aligned so that the alignment target 5 coincides with the cross-hairs 23, which is shown in Figure 7b. During this alignment, the barrel and the sight are monitored closely. If there is a need for alignment, the alignment target 5 and the marker 22 take up the positions shown in Figure 7a, which are not centred over each other. In this connection, it can be pointed out that it is also possible to commence the whole alignment procedure by aligning the sight as a first step, in the way stated at the start of this paragraph, so that the alignment target 5 coincides with the cross-hairs 23.

The final alignment is then carried out by correcting settings in the firing control system for alignment of the barrel to the sight, so that the marker 22 and the alignment target 5 are centred over each other while retaining the sight setting with coinciding cross-hairs 23 and alignment target 5. The final result is shown in Figures 8a and 8b. The barrel 2 and the sight 3 are now aligned with each other and the arrangement 7 can be released and withdrawn from the barrel through the breech .

Finally, it can be mentioned that the cables 19 and 20 shown in Figure 4 are used to activate and deactivate the clamping of the arrangement 7 inside the barrel and to control the rotation of the camera 9. The invention is not limited to the embodiments described above, a plurality of alternative embodiments being possible within the framework of the invention described by means of the claims .

Claims

Case 3871Claims

1. Method for use with a barrelled weapon (2) mounted on a gun carrier (1) such as an armoured car or the like, with cross-hairs sight (23) or the like mounted on the gun carrier, for making it possible to align the centre line of the barrel (2), in particular the front part of the centre line towards the muzzle, with the weapon's sight (23) completely from the interior of the gun carrier (1) , characterized in that an alignment marker (7) is used as reference for the centre line of the barrel, which alignment marker is moved forward through the barrel from its breech, and is in the form of an image-generating sensor (9) with its line of vision along the direction of fire of the barrel and with its field of vision including the centre line (6) of the barrel (2), which alignment marker, during the aligning operation, is fixed in the barrel, with images displayed by the sensor (9) being co-ordinated with the sight image of the weapon's sight (23).

2. Method according to Claim 1, characterized in that the position of the centre line within the field of vision of the image-generating sensor (9) is determined by the sensor being rotated around the centre line, without its fixing in a longitudinal or lateral direction being displaced, with the point within the sensor's image that does not move being utilized (26) as marker for the centre line, and with this point being marked by movable cross-hairs (22) or the like on the sensor's image (21) and thereafter being utilized for-aligning of barrel and sight.

3. Method according to Claim 1 or 2, characterized in that the image-generating sensor (9) and its fixing devices (8-11) are moved forward from the barrel's (2) breech to the muzzle by means of a retractable device, in the form of a telescopic rod, a pantograph, a steel band that can be rolled up or the like, which retractable device can be operated from the interior of the gun carrier (1) .

4. Arrangement for use with a barrelled weapon (2) mounted on a gun carrier (1) such as an armoured car or the like, with sight (3) mounted on the gun carrier, for making it possible to align the centre line of the barrel (2) , in particular the front part of the centre line, with the weapon's sight (3) completely from the interior of the gun carrier, characterized in that it comprises a sight marker (9) arranged in the same, mounted in a carrier (7) designed for this purpose, in the form of an image-generating sensor (9) with its line of vision along the longitudinal axis of the carrier (7) and with its field of vision centred with the carrier's longitudinal axis, which image-generating sensor displays an image on a display (21) which can be co-ordinated with the cross-hairs (23) or the like in a sight image, and with the carrier (7) holding the sensor having at its front and back parts fixing devices (10,_. 11) that are self-centring in the barrel and that can be clamped against the inside of the barrel .

5. Arrangement according to Claim 4, characterized in that the image-generating sensor (9) can be rotated around the longitudinal axis of the carrier.

6. Arrangement according to any one of Claims 4 or 5, characterized in that the carrier (7) for the sight marker (9)^" is^" designed to be moved forward from the breech of the gun (2) to the muzzle of the barrel by means of an associated arrangement in the form of a steel band that can be rolled up, a pantograph, a telescopic rod or the like, while at the same time the sensor (9) mounted in the carrier (7) is connected to the display (21) displaying the sensor's vision image via a video cable (18) running through the barrel (2) .

7. Arrangement according to any one of the preceding Claims 4-6, characterized in that the display (21) that displays the image-generating sensor's (9) image is provided with a movable marker (22) for marking the point (26) in the sensor's image that remains stationary when the sensor is rotated in the carrier.

8. Arrangement according to any one of the preceding Claims 4-7, characterized in that the distance between the self-centring fixing points (10, 11) for the sight marker's (9) carrier corresponds to two to four times the calibre of the gun concerned.

9. Arrangement according to Claim 8, characterized in that the fixing points (10, 11) for the sight marker's carrier consist of locking balls (11) moved upon command towards the inside of the barrel 2 by conical clamping sleeves (12, 13) .

10. Arrangement according to any one of the preceding Claims 4-9, characterized in that it comprises means that prevent the sight marker's carrier moving outside the muzzle of the barrel.

11. Arrangement according to any one of the preceding Claims 4-10, characterized in that the image-generating sensor consists of a video camera.