GB2304871A - Shotgun test target apparatus - Google Patents

Abstract

Apparatus for testing the shot pattern produced by a shotgun comprises an elongate generally horizontal rail (1,2), a carriage( 8) arranged to run along the rail, the carriage carrying mounting means for holding a target sheet, and drive means (4,6,7) for propelling the carriage along the rail between a first rest position adjacent to one end of the rail and a second rest position adjacent to the other end of the rail. The drive means comprises an electric motor drawing an endless lever of cable attached to the carriage, and control means are provided to supply power to the motor for a fast period of time to accelerate the carriage to a derived speed, and then to reverse the power supply to the motor for a second period to bring the carriage to a halt.

Description

SHOTGUN TEST TARGET APPARATUS Field of the Invention This invention relates to apparatus for use in the testing of shotguns.

Background to the Invention The performance of a shotgun is dependent upon several variable factors, in particular the design of the gun itself, the design and type of the cartridge used, and the design of the choke employed in the barrel of the gun. For example, the same cartridge used in the same gun, but with different chokes will produce differ ent patterns of shot, while changing cartridges will give a wide variety of shot patterns. In competition shooting, the shot pattern is one important factor in the results obtained. If the shot disperses too widely, it is possible for a moving clay target, for example, to pass through the gaps in the pattern untouched, even though the aim was otherwise exact.On the other hand, if the shot pattern is too tight, the aim must be more precise to ensure a hit. 4 It is usual practice, therefore, to test the performance of different shotgun set-ups with different types of cartridge by shooting at test targets, for example of card, so that the resulting pattern can be examined and compared with other configurations. This practice, however, only gives the user some of the relevant information, since the dispersal of the shot from a gun occurs not just spatially, but also temporally; the shot does not all leave the barrel at the same instant, and differences in the final shape of the individual shot and the exit speeds from the barrel all cause the time at which the shot reaches the target to vary. For a moving target, this gives rise to quite a different result than that obtained for a fixed target.

Summary of the Invention According to the invention, there is provided apparatus for testing the shot pattern produced by a shotgun, comprising an elongate generally horizontal rail, a carriage arranged to run along the rail, the carriage carrying mounting means for holding a target sheet, and drive means for propelling the carriage along the rail between a first rest position adjacent to one end of the rail and a second rest position adjacent to the other end of the rail.

The drive means preferably comprises an electric motor driving an endless loop of cable attached at one point on its length to the carriage, control means being provided to supply power to the motor for a first predetermined time period to accelerate the carriage to a desired speed, and then to reverse the power supply to the motor for a second predetermined time period, whereby the motor acts as a brake to bring the carriage to a halt at a desired point on the rail. The motor is suitably provided with power from a battery, so that the apparatus can readily be used in remote locations away from mains electrical power. The control means may be arranged to prevent power being applied to the motor unless the carriage is in a predetermined starting position. The presence of the carriage at the starting position may be signalled by a microswitch located adjacent to the rail.The target may be moved left-to-right and right-to-left alternately, providing variety of target shooting and minimising the delay between target runs, since it is not necessary to return the carriage to one end of the rail before commencing a run of the target.

Protective spring stops may be provided at each end of the rail to arrest the movement of the carriage safely should the normal braking measures fail. The stops may incorporate crushable metal members or the like in addition to the spring to assist in absorbing the kinetic energy of the carriage, and thereby arrest the carriage in a shorter distance.

The rail is suitably mounted on a plurality of stands spaced along its length, the stands preferably being adjustable in height to accommodate variations in ground level and maintain the rail substantially level, obviating the need for costly preparation of the site.

Remote operating means may be provided for the operation of the apparatus. This may suitably comprise a hand-held controller linked to the control means by a cable, although radio or other wireless operation may alternatively be employed.

Audible warning means may be incorporated to signal the commencement of the operation of the motor. Thus, for example, a continuous tone may be generated when the motor start button is pressed, power only being supplied to the motor after a delay, at the end of which the tone changes to an intermittent tone.

Visible warning signals may also be generated.

Where the carriage is driven via an endless cable, it has been found that a plastics covered wire cable is especially suitable, the drive pulleys preferably being shaped so as to conform more closely with the external configuration of the cable.

With such an arrangement, it has been found that very precise positional control of the carriage can be achieved, with a very small degree of slippage occurring. In this way, accurate control of the carriage can be achieved solely on the basis of the timing of the power and braking cycles of the motor.

The speed of the carriage can be arranged closely to reproduce that of clay targets and the like, thus providing test conditions that simulate accurately those experienced in competitions, but consistently, and with a record of results via the target sheet, so that useful comparisons can be made between results obtained by varying cartridge types, choke design or gun design. The target sheets are suitably of card or plastics material, printed with a suitable clay target outline, or the like, so that the shot pattern relative to the outline is recorded in the form of holes in the target for subsequent study.

The apparatus of the invention will be useful not only to the gun-users, but also to the manufacturers of guns, chokes and cartridges in improving the design of their products.

Brief Description of the Drawings In the drawings, which illustrate an exemplary embodiment of the invention: Figure 1 is a diagrammatic view of the apparatus; Figure Z is an elevation on an enlarged scale of the motor drive for the apparatus shown in Figure 1; Figure 3 is a sectional elevation, on a slightly less enlarged scale than Figure 2, of the rail and the carriage thereon; Figure 4 is a diagram of the motor control circuit for the apparatus; and Figure 5 is general functional diagram for the control of the apparatus.

Detailed Description of the Illustrated Embodiment Referring first to Figure 1, the apparatus comprises an elongate rail, in the form of a vertically-spaced pair of horizontal square section tubes 1 joined at intervals by vertical spacers 2. The rail is supported by a plurality of vertical stands 3 whose heights are adjustable to accommodate variations in ground level. At one end of the apparatus, a control cabinet 4 is mounted on a pair of end stands 5, while at the other end a return pulley 6 is mounted on a vertical spindle. An endless loop of plastics covered wire rope 7 runs around the pulley 6, and a corresponding motor pulley, described hereinafter with reference to Figure 2, in the control cabinet. The rope is attached to a carriage 8 which mounts the target sheet and which runs along the rail. In use, the carriage 8 is propelled along the rail at speed by the motor via the wire rope 7, the motor rapidly accelerating the carriage for a predetermined period of time, then allowing the carriage to run along under the momentum gained for a very short time period before the motor is connected to a resistor instead of the power supply to cause the carriage to decelerate, coming to a halt before the end of the rail is reached. The carriage can then be moved manually to a start position at the adjacent end of the rail, ready to perform a return run after the target sheet has been removed for inspection and a fresh sheet mounted on the carriage.

The motor 9 illustrated in Figure 2 is a direct current permanent magnet motor of a similar construction to a motor vehicle starter motor, but is reversible.

It provides a very high torque on starting so that the carriage accelerates rapidly to its maximum speed, and can function as an electromagnetic brake when the power supply is disconnected and a simple coil is connected across its terminals to dissipate the power generated by the motor. The motor can be operated in the reverse direction simply by supplying power to it with reversed polarity. The motor pulley 10 is mounted on a vertical spindle 11 held by a pair of bearings 12 whose mounting bracket 13 is bolted to the main frame (not shown). The pulley 10 has a circumferential groove 14 which is configured so as to conform closely with the exterior shape of the wire rope 7, so as to ensure that the maximum grip is achieved of the rope on the pulley.

The spindle 11 is coupled to the motor 9 by way of a jaw coupling 15 comprising inter-engaging teeth 16 on the two halves of the coupling, and resilient blocks 17 between the teeth to absorb the shock loading on the teeth during startup and stopping, in particular.

Power is supplied to the motor through a supply lead 18, the body of the motor providing the return path for the current.

Referring to Figure 3, the carriage 8 comprises uprights 19, only one of which is shown, reduced in length for the sake of convenience of illustration. The uprights 19 form part of a frame, to which a detachable mounting member (not shown) which carries the target sheet may be readily attached. An upper crossmember 20 carries a pair of vertical rollers 21 which run along the upper tube 1 of the rail and which support the full weight of the carriage. Upper horizontal rollers 22 guide the carriage along the upper tube, while lower horizontal rollers 23 cooperate with the lower tube 1 of the rail to stabilise the movement of the carriage further. The horizontal rollers 22 and 23 on the target side of the carriage are provided with covers 24 to protect them from damage by the shot striking the target and passing through the target sheet.The rope 7 is secured to the carriage by a mounting 25 above the vertical rollers 21.

The electric motor control system for the apparatus is represented diagrammatically in Figure 4. The motor 9 is supplied from a 12 or 24V battery 40 via a 600A fuse 41 and a series of electro-mechanical power relays 42 to 47, each controlled by a respective smaller electro-mechanical relay which is in turn controlled by a monostable, these other elements of the circuit not being shown. This cascaded control is necessary because of the very high current drawn by the motor 9.

All the relays are of the normally open type, and are illustrated in the open position. A first pair of the relays 42 and 43 are closed to supply power to the motor 9 to drive it in the forward direction, and a second pair of relays 44 and 45 can be closed, while the first pair are opened, to supply power in the reverse direction. A fifth of the relays 46 can be closed to complete the power circuit to the motor, while the final relay 47 is closed, when the fifth relay 46 is opened, to introduce a small resistor 48 (in practice simply a few turns of insulated wire) into the motor circuit when the current is reversed in the braking mode of the apparatus.

The sequence of operations is: 1. set up direction by energising relays 42 and 43 for one direction or relays 44 and 45 for the reverse direction; 2. run the motor, by energising relay 46; 3. initialise braking by opening relay 46, and setting up the reverse direc tion from that set up in (1); 4. apply braking by energising relay 47; 5. brake time-out - open relay 47; 6. general failure time-out (explained in more detail hereinafter with refer- ence to Figure 5) - open all relays.

Figure 5 illustrates the control circuit diagrammatically. At the heart of the control circuit is the process control logic 50, which controls the motor 9 via the motor control circuit 51, which includes the relays 42 to 48 and the electronics and other relays controlling their operation. An overspeed and slip detection circuit 52 may be provided to monitor the speed of the motor and the speed of the rope dur- ing operation of the motor 9 and signals to the control logic 50 if an overspeed or slip condition is detected. In response, the logic 50 can apply braking.Position detectors 53, in the form of microswitches mounted adjacent to the rail so as to be contacted by the carriage as it passes, signal to a park detect and arm delay circuit 54, whose function is to ensure that the starter button cannot be armed unless the carriage is at the correct starting position at one end or other of the rail. A remote control push-button 55 is linked to a push button detect circuit 56 which signals a start signal to the logic 50 if the arm delay is not operative. The logic 50 then causes a warning buzzer driver 57 to operate a warning buzzer 58 to sound for a predetermined period, changing from a continuous to an intermittent tone just before the motor is powered. If the button is released while the buzzer is still sounding, the system is reset, and the start sequence has to be repeated before the motor can be operated.

The safe condition detection and initial motor pulse circuit 59 determines that the all indications are normal before sending to the motor an initial pulse of power lasting a predetermined short period, for example 200 ms. This starts the movement of the carriage away from its start position and past the position detection microswitch 53, which is opened briefly as the carriage passes. The carriage away timer/safety shutdown 60 receives the signal from the microswitch 53 as the carriage passes and determines whether the pulse is still continuing; if it is not, which means that the carriage has not left the starting position, perhaps because of an obstruction, the control system is shutdown and all relays opened. If the carriage passes the microswitch within the initial pulse period, the main power timer to the motor is enabled, as hereinafter described.

A half way timer 61 may also be provided, if desired. This receives an input from a detector on the track at approximately the half-way point when the carriage passes. A Hall effect device may be used, for example. If the half-way point has not been reached by the carriage by a predetermined time, as indicated by the absence of the signal from the detector, the controller may be arranged to bring the carriage to a halt safely. For example, the controller could determine the motor speed at the half-way point and use fuzzy logic to brake the carriage appropriately.

The end of run timer 62 determines the power-on period for the motor.

This may be adjustable to enable the period to be set according to the precise conditions and apparatus in a given installation. Two such timers may be provided, one for each direction, so that the motor power periods for each direction may be varied one from another to take account of variations in motor performance when running in two opposite directions, and variations from the horizontal of the track. In some circumstances, it may be desirable or necessary to incorporate a slope into the track, and the two timers may then be adjusted to compensate for the uphill and downhill running of the carriage. A brake delay may be incorporated in this stage. This could be a time delay sufficient to allow for the switching time of the relays to prevent a short circuit in the motor supply circuit.In practice, it has been found that no such delay is necessary, but in other circumstances it might be desirable to provide a short delay.

The brake control timer 63 reverses the power to the motor, at the same time incorporating a small resistance into the motor circuit during the braking to protect the battery and the motor from excessive currents. the reslstance also serves to control the braking to prevent it being too violent in effect, thus reducing the risk of damage to the drive mechanism, in particular the cable.

The cycle complete and reset controller 64 provides an overall timer for a period within which all actions in the cycle of the apparatus should be completed.

At the end of the time period, the controller resets all the monostables to reset the relays in turn.

A power-on reset circuit 65 may be provided to send a rest signal to all devices in the electronic control of the apparatus when the power is first connected, to ensure that all devices are set to the correct starting state. The design of the present apparatus as described is such that this circuit is not required; the reset characteristic is inherent in the design.

Claims (16)

1. Apparatus for testing the shot pattern produced by a shotgun, comprising an elongate generally horizontal rail, a carriage arranged to run along the rail, the carriage carrying mounting means for holding a target sheet, and drive means for propelling the carriage along the rail between a first rest position adjacent to one end of the rail and a second rest position adjacent to the other end of the rail.

2. Apparatus according to Claim 1, wherein the drive means comprises an electric motor driving an endless loop of cable attached at one point on its length to the carriage, control means being provided to supply power to the motor for a first predetermined time period to accelerate the carriage to a desired speed, and then to reverse the power supply to the motor for a second predetermined time period, whereby the motor acts as a brake to bring the carriage to a halt at a desired point on the rail.

3. Apparatus according to Claim 2, wherein the motor is provided with power from a battery.

4. Apparatus according to Claim 2 or 3, wherein the cable is a plasticscovered wire cable.

5. Apparatus according to Claim 4, wherein the wire cable passes over pulleys shaped to conform closely with the external shape of the cable.

6. Apparatus according to any of Claims 2 to 5, wherein the control means is arranged to prevent power being applied to the motor unless the carriage is in a predetermined starting position.

7. Apparatus according to Claim 6, comprising a microswitch located adjacent to the rail arranged to signal the presence of the carriage at the starting position.

8. Apparatus according to any preceding claim, comprising protective spring stops at each end of the rail to arrest the movement of the carriage safely should the normal braking measures fail.

9. Apparatus according to Claim 8, wherein the stops incorporate crushable metal members or the like in addition to the spring to assist in absorbing the kinetic energy of the carriage.

10. Apparatus according to any preceding claim, wherein the rail is mounted on a plurality of stands spaced along its length.

11. Apparatus according to Claim 10, wherein the stands are adjustable in height to accommodate variations in ground level.

12. Apparatus according to any preceding claim, comprising remote operating means for controlling the operation of the carriage.

13. Apparatus according to Claim 12, wherein the remote operating means comprises a hand-held controller linked to the control means by a cable.

14. Apparatus according to Claim 12, wherein the remote operating means comprises a hand-held controller linked to the control means by radio or other wireless means.

15. Apparatus according to any preceding claim, comprising audible warning means to signal the commencement of the operation of the motor.

16. Apparatus for testing the shot pattern produced by a shotgun, substantially as described with reference to, or as shown in, the drawings.