CA3037420C - Protection system for laser cutting machine - Google Patents

Abstract

A laser cutting tool with protective enclosure assembly for manipulating a workpiece on a movable platen includes a frame, a top protection assembly, a middle protection shield, a bottom protection assembly and a laser torch head. The top protection assembly, middle protection assembly, and bottom protection assembly are removably mounted to the frame such that they form a cavity enclosing only substantially the laser torch head.

Description

PROTECTION SYSTEM FOR LASER CUTTING MACHINE
FIELD OF THE INVENTION
[0001] The present invention relates generally to a protection system and more particularly, to a protection system for a laser cutting machine.
BACKGROUND OF THE INVENTION

[0002] Laser cutting is a technology that uses a laser to cut materials, and is typically used for industrial manufacturing applications. Laser cutting works by directing the output of a high-power laser most commonly through optics. A laser cutting machine features a cutting head generating a laser beam that moves in both of the horizontal dimensions over a workpiece loading onto a table. The focused laser beam is directed to the workpiece, part of which is then melted, burns, and vaporizes away. A cut edge with a high quality surface finish is therefore created.

[0003] Lasers enclosed in the laser cutting machines are capable of emitting high levels of energy and can therefore be dangerous to the eyes and skin of its operator.
The use of the laser cutting machine can also impose a number of hazards including toxic gases and fumes and inhalable particles. Moreover, the possible random reflection of the laser light may burn the retina of an operator when the laser initially pierces the workpiece.
Therefore, coupling a protective enclosure apparatus to a laser cutting machine is essential to the safe operation of the machine.

[0004] Most existing protective enclosures cover the entire laser cutting machine and thereby form a chamber. This not only results in a bulky machine, but also requires a pallet shuttle system to be installed onto the laser cutting machine for loading and unloading the workpiece into the chamber. This solution drives up the financial cost as well as the operation time of the laser cutting machine.

[0005] There therefore exists a need within the industry for the ability to increase the effectiveness of a protection system for the laser cutting machine, while avoiding the abovementioned drawbacks of known protective enclosure apparatuses.
SUMMARY OF THE INVENTION

[0006] With the forgoing concerns and needs in mind, it is the general object of the present invention to provide a protection system.

[0007] It is another object of the present invention to provide a protection system for a laser cutting machine.

[0008] It is another object of the present invention to provide a protection system for a laser cutting machine that permits the operator of the laser cutting machine to directly load and unload the workpiece onto and off the table without having to wait for the pallet shuttle exit a typical protective enclosure apparatus.

[0009] It is another object of the present invention to provide a protection system for a laser cutting machine that allows the coil feeding of the workpiece directly onto the table at a reasonable financial cost.

[0010] It is another object of the present invention to provide a protection system of a laser cutting machine guard surround the laser torch head only and therefore reduce the overall volume of the laser cutting machine.

[0011] These and other objectives of the present invention, and their preferred embodiments, shall become clear by consideration of the specification, claims and drawings taken as a whole.
BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:

[0013] Figure 1 illustrates a diagram of a prior art laser cutting machine, according to one embodiment of the present invention.

[0014] Figure 2 illustrate an isomeric, side view of a protection system, according to one embodiment of the present invention.

[0015] Figure 3 is an enlarged view of the protection system, shown in Figure 2, according to one embodiment of the present invention.

[0016] Figure 4 illustrates the protection system of Figures 2 and 3 as a middle protection screen is detached from the protection system, according to one embodiment of the present invention.

[0017] Figure 5 illustrates an enlarged sectional view of a top brushes assembly according to one embodiment of the present invention.

[0018] Figure 6 illustrates an isomeric, side view of a top brushes assembly, according to one embodiment of the present invention.

[0019] Figure 7 illustrates an isomeric, side view of a bottom brushes assembly, according to one embodiment of the present invention.

[0020] Figure 8 illustrate an enlarged sectional view of a bottom brushes assembly, according to one embodiment of the present invention.

[0021] Figure 9 illustrates a cut-away of the top and bottom portions of the protective enclosure according to one embodiment of the present invention.

[0022] Figure 10 shows an enlarged bottom portion of the protective enclosure, according to one embodiment of the present invention.

[0023] Figure 10A is an enlarged, detailed cross-sectional view of area 10A of Figure 10.

[0024] Figure 11 illustrates the brush cup assembly as removed from integration with the lower part of the protective enclosure, according to one embodiment of the present invention.

[0025] Figure 12 illustrates a safety switch, according to one embodiment of the present invention.

[0026] Figure 13 illustrates a close-up sectional view of the bottom protection assembly, according to one embodiment of the present invention.

[0027] Figure 14 illustrates a non-linear path, according to one embodiment of the present invention; and

[0028] Figure 15 illustrates a perspective view of the laser head assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0029] Figure 1 illustrates an isomeric side view of a workpiece manipulation apparatus having a laser cutting machine, and its protective enclosure apparatus 100. A
cutting laser (not shown) is positioned inside a protective enclosure apparatus 101. A
pallet shuttle 102 locates in close association with the protective enclosure apparatus 101. A
workpiece can be loaded and unloaded onto and off the pallet shuttle 102. The pallet shuttle 102 then carriers the loaded workpiece, enters into and exits the protective enclosure apparatus 101 through a protective enclosure apparatus enclosure door 103.
In particular, to load and unload the workpiece to be processed by the laser cutting machine onto the pallet shuttle 102, the pallet shuttle 102 must exit the protective enclosure apparatus 101.

[0030] It will therefore be readily appreciated that known laser enclosures require enclosing the totality, or a great degree, of the workpiece manipulation apparatus itself, which is both expensive and cumbersome. When the workpiece and (preferably, movable) platen upon which it is transported are both captured inside the laser enclosure, as with the known apparatus shown in Figure 1, efficiencies are lost due to excessive set-up time and expense, as well as making the workpiece and cutting laser largely inaccessible without undue stoppage and shutdown of the apparatus as a whole.

[0031] Figure 2 illustrates an isomeric, side view of a protection system 10, according to one embodiment of the present invention. In particular, Figure 2 illustrates the protection system 10, as integrated with a laser torch head 80, a bridge 90 for supporting the laser torch head, and a workpiece 91 being processed. As it will be appreciated, the laser torch head 80, the bridge 90 and the workpiece 91 are only partially shown in Figure 2, so as to permit illustration of the protection system itself, and its preferred placement with respect to the bridge 90, the laser torch head 80 and the workpiece 91.

[0032] While the present invention is being described in connection with the bridge 90 and the laser torch head 80 shown in Figure 2, it will be readily appreciated by one of ordinary skill in the art the present protection system 10 could be integrated into any laser cutting head, regardless of the specific type of the same, without departing from the broader aspects of the present invention.

[0033] As most clearly shown in Figure 2, the protection system 10 of the present invention is moveably mounted to the bridge 90 so as to move therealong. The bridge 90 itself is adapted to move in a direction perpendicular to the moving direction of the protection system 10, so as to cut the workpiece 91, as desired. Additionally, the protection system 10 is designed such that the laser cutting head can be mounted on a motorized actuator inside the protection system 10 allowing the laser cutting head to be raised or lowered automatically for the purpose of focusing the laser beam or to accommodate slight variations in thickness of the material to be cut without affecting the position or downward force of the brush guard on the material being cut.
This enclosed motorized actuator reduces the risk of accidental exposure of the laser light.

[0034] The protection system 10 includes a frame 11, a top protection assembly 40, a middle protection shield 20, and a bottom protection assembly 60, thereby forming a cavity where a laser torch head 80 locates, so as to prevent the escaping of reflected laser light when the laser torch head 80 cuts the workpiece 91.

[0035] As will be appreciated, and in stark contrast to the enclosure of the apparatus shown in Figure 1, it is an important aspect of the present invention that it is only the laser head 80 itself, which is enclosed by top, middle and bottom assemblies, 40, 20 and 60 respectively. Thus, the protection system/enclosure of the present invention does not extend to the apparatus as a whole, nor does the enclosures encompass the movable platen upon which the workpiece is arranged.

[0036] Turning now to Figures 3 and 4, in combination, the middle protection shield assembly 20 of the protection system 10 is illustrated in more detail. A light shield 23 is a preferably semi-translucent laser safe shield, so as to permit the operator of the laser cutting machine having a view of the inside of the cavity of the protection system 10, meanwhile prevents the reflected laser light escaping from the cavity. The light shield includes a planetary gasket 24. The light shield 23 is removably fixed to the frame 11 via four interlock switches 22 embedded in the frame 11. In alternative embodiments, the middle protection shield assembly 20 is mounted on hinges or vertical slides which are in conjunction with latches, the planetary gasket 24, and safety interlock switches 22, so as to allow interlocked access to the laser head for maintenance while preventing exposure of the laser by an operator.

[0037] In particular, the present invention envisions that the light shield 23 is preferably a Laservision P5P10 IR fiber laser safety window, for blocking various light rays across multiple spectrums, although other suitable shielding may be utilized without departing from the broader aspects of the present invention.

[0038] It should be noted that the light shield 23 must be secured to the frame 11 and the interlock switches 22 must be in contact with the light shield 23 in order for the laser torch head 80 to start working. Indeed, the there are several safety switches integrated with the light shield 23, all of which must be actuated in order for the laser head 80 to be permitted to operate.

[0039] As shown, Figure 3 illustrates the middle protection shield 20 in an enclosed position. The light shield 23 is secured onto the frame 11 via four interlock (safety) switches 22. The interlock switches are in a locked position and therefore permits the laser torch head 80 to start working. Figure 4, in contrast, illustrates the middle protection shield 20 in an opened position. The light shield 23 is removed from the frame 11. The interlock switches trip to an unlocked position upon the detaching of the light shield 23 from the frame 11. Therefore, the laser torch head 80 is unable to start working until the light shield 23 is secured to the frame 11 again.

[0040] The frame 11 is preferably welded so as to provide a continuous housing, thereby preventing radiation from escaping during operation of the laser head 80.

[0041] Figure 5 and 6, in combination, illustrate a sectional view of the top protection assembly 40. In one preferred embodiment, the top protection assembly 40 includes a top support cover 41 having an opening, and at least brush assembly 44 positioned to cover the opening of the top support cover 41. The brush assembly is connected to the top support cover 41 via a bracket 42.

[0042] The brush assembly 44 includes one pair of brush holders 45 which are in connection with the bracket 42, and a pair of brushes 46, each of which comprises a plurality of brush bristles. One end of the brush 46 is received by the brush holder 45 in a brush socket. Two brushes in a pair are positioned in an opposite direction at the same vertical level, so as to permit the other ends of the two brushes to be facing and contacting each other. Therefore, the brushes assembly 44 prevents the reflected laser light from escaping the cavity from the top protection assembly 40, meanwhile permits any electrical cable, light cable or power cable connected to the laser torch head 80 to pass through the top protection assembly 40 and enter into the cavity. The cables therefore can move upward and/or downward freely without congesting the top protection assembly 40.

[0043] It shall be noted that in a preferred embodiment, three layers of the brushes assembly 44 are arranged vertically and connected to the bracket 42. However, any number of layers can be used to optimize the protection effect of the top protection assembly 40.

[0044] The top protection assembly 40 is connected to the frame 11 via two interlock (safety) switches 48. The two interlock switches 48 are in a locked position and permit the laser 80 to start working once the top protection assembly 40 is correctly fixed to the frame. However, if the top protection assembly 40 is removed, the two interlock switches 48 trip to an unlocked position and therefore prevent the laser torch head 80 from starting. In another embodiment, the top protection assembly 40 may include a solid assembly with the utilities passing through the guard assembly walls by means of bulkhead connectors and plugs, so as to enhance safety and/or provide a more tightly sealed chamber, which can be vented more effectively in the case of unpleasant or toxic fumes generated during the cutting process.

[0045] Figure 7 and 8, in combination, illustrate the bottom protection assembly 60. The bottom protection assembly 60 includes a bottom cover 61 having an opening to permit the laser torch head 80 extending therethrough and applying the laser light onto the workpiece 91 via a laser application tip unit 82. The bottom protection assembly 60 further includes a bottom brushes cup assembly 65. The bottom cup assembly 65 is arranged in a position relative to the opening on the bottom cover 61 so as to permit the operation of the laser torch head 80 on the workpiece 91.

[0046] The bottom brush cup assembly 65 includes a circular base 62 connected to the bottom cover 61 via two interlock switches 69. An opening in the center of the circular base 62 is matched with the opening on the bottom cover to permit the laser torch head extending therethrough. The circular base 62 has at least one socket in a circular shape for receiving an array of brushes 66 arranged in the same circular shape surrounding the central opening on the circular base 62. The brushes 66 are attached to the circular base 62011 one end, and extend downward with the other end of the brushes 66 directly contacting the workpiece 91 thereby ensures that the cavity of the protection system 10 is enclosed when the laser torch head 80 is performing cutting function on the workpiece 91.

[0047] As will be discussed in more detail later, the brushes 66 includes a solid rubber membrane 67(122) embedded between the bristles 68. It is yet another important aspect of the present invention that due to the specific use of the brushes 66 and how these bristles/brushes may be compressed to a degree, i.e., slightly bent, when in contact with a workpiece, the protection system 10 of the present invention effectively prevents the reflected laser light from escaping the cavity when the workpiece 91 moves in a vertical direction sporadically during the laser cutting process for the workpiece 91.

[0048] In one preferred embodiment, two arrays of brushes are arranged and received in two separate concentric circular sockets locate on the circular base.
However, it should be noted that any number of array of brushes and the relevant receiving circular sockets can be arranged, so as to optimize the protection effect of the bottom protection assembly 60.

[0049] The circular base 62 is connected to the bottom cover 61 via two joints and two safety interlock switches 69. The two interlock switches 69 are in a locked position and permit the laser torch light 80 to start working once the bottom brushes cup assembly 65 is correctly fixed to the bottom cover 61. However, if the bottom brushes cup assembly 65 is removed, the two interlock switches 69 trip to an unlocked position and therefore prevent the laser torch head 80 from starting.

[0050] The safe operation of the laser head 80 is further increased by arranging a senor (unillustrated) in the area of the base 62, for the purposes of detecting whether a workpiece is positioned adjacent the laser head 80. If the sensor does not detect a workpiece in the area adjacent to the laser head 80, the laser head 80 will not be permitted to operate. Preferably, the laser head 80 will be prevented from operating if the sensor does not detect a workpiece within approximately 1mm below the laser head 80, although it will be readily appreciated that other distances may be instead utilized without departing from the broader aspects of the present invention.

[0051] Figure 9 illustrates a cut-away of the top and bottom portions of the protective enclosure 10. As shown in Figure 9, the light shield 23 and frame 11 interact and are sized and positioned such that there is an overlap, 100/102, between a raised edge of the frame 11 and the light shield 23, thus ensuring that extraneous light from the laser head 80 does not escape the protective enclosure 10.

[0052] Figure 10 shows an enlarged bottom portion of the protective enclosure 10, as well as a sectional view of one of a pair of spring-loaded bush biasing devices 108. As illustrated in Figure 10, the bottom brush cup assembly 65 includes an upper mounting plate 110, which itself is releasably attached to a base mounting plate 112 that is operatively attached to the pair of spring-loaded brush biasing devices 108.

[0053] As will be appreciated, the spring-loaded brush biasing devices 108 include preferably an articulating ball joint 114 and a biasing spring/element 116.
The biasing device 108 thereby act to allow the brush cup assembly 65 and integrated bristles to tilt freely while being constantly biased downwardly into contact with the workpiece below, thus accommodating and remaining in tight contact with the workpiece, regardless of differences or irregularities in the workpieces contour and/or slope.
The ball joint 114 may comprise a magnetically coupled design to permit the brush biasing devices 108 to separate cleanly without causing permanent damage to the guard assembly in the case of a hard collision. The presence of the two safety interlock devices 69 will ensure deactivation of the laser in the case of a collision and subsequent separation of the ball joint 114.

[0054] As will be appreciated, the brush cup assembly will incur wear during use, and as such, is a consumable part which must be inspected and replaced from time to time.
For its part, Figure 11 illustrates the brush cup assembly as removed from integration with the lower part of the protective enclosure. As further shown in Figure 12, a safety switch 120 may be integrated with the protective enclosure to detect the presence of the brush cup assembly 65. The safety switch 120 is preferably a compression limit type switch or coded RFID switch, and is sensitive enough to determine when the bush cup 65 is not engaged or is improperly installed or becomes loose, although other types of sensors and switches may be utilized for this purpose without departing from the broader aspects of the present invention. If the safety switch 120 does not detect the existence and proper installation of the bush cup assembly 65, the laser head 80 would be prohibited from operation.

[0055] As discussed previously, the protective enclosure of the present invention includes many features that make the safe operation of the laser head 80 possible.
Figure 13 illustrates a close-up sectional view of the bottom protection assembly 60. As shown in Figure 13, and in a preferred embodiment, the bush cup assembly 65 includes two concentrically aligned brushes/brush rings 66, each of which includes a solid rubber membrane 122 embedded within each of the concentrically aligned brush rings 66.

[0056] As will be appreciated, the bushes 66 themselves are formed from material, such as but not limited to rubber, that is both resiliently flexible as well as being able to maintain structural integrity even in high temperature environments. An interior, preferably fabric, liner 124 is disposed between the brushes 66 and the laser head 80, in order to protect the brushes from damage due to operation of the laser head 80. Figure 14 shows the non-linear path 126 that light emanating from the laser head 80 must follow, in order to escape the protective enclosure of the present invention.

[0057] As discussed previously, one important aspect of the present invention is that the laser head 80 is much more easily accessible than known devices, and this additional functionality is shown in Figure 15. As shown in Figure 15, the light shield 23 is movably mounted to linear guides 128, which allow the light shield 23 to be moved up or down (to a raised, or lowered, position) for the quick adjustment of, e.g., the focus of the cutting beam, or the like. A pair of proximity sensors 130 are therefore utilized to determine if and when the light shield is in its lowered position, and only allows operation of the laser head 80 if the sensors 130 agree that the light shield is in the proper, protective (lowered) position.

[0058] As will be appreciated from a review drawing figures 1-15 and their associated discussion, the present invention has developed a laser cutting apparatus for the manipulation of workpieces, preferably metal workpieces. However, in contrast to known devices, the present invention utilizes a protective enclosure about the laser head only, thereby leaving the majority of the apparatus open to inspection and manipulation, as necessary. Moreover, the present invention utilizes a series of integrated safety switches, any of which can cause the operation of the laser head to be halted or prohibited, should any of these safety switches indicate an unsafe situation.
These safety switches can of course be integrated with a machine-stop button, preferably in series, so as to make the operation of the laser head 80 as safe as possible.

[0059] Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of this disclosure.

Claims (20)

THE EMBODIMENTS OF THE INVENTION FOR WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A laser cutting tool with protective enclosure assembly for manipulating a workpiece on a movable or stationary platen, said laser cutting tool with protective enclosure assembly comprising:
a frame;
a top protection assembly;
a middle protection shield;
a bottom protection assembly;
a laser torch head;
wherein said top protection assembly, said middle protection assembly, and said bottom protection assembly are removably mounted to said frame;
wherein said top protection assembly, said middle protection assembly, and said bottom protection assembly form a cavity enclosing only substantially said laser torch head; and a safety interlock assembly in communication with said frame, said top protection assembly, said middle protection assembly and said bottom protection assembly.

2. The laser cutting tool with protective enclosure assembly according to claim 1, wherein:
said middle protection shield includes a light shield having a planetary gasket disposed on an edge of said light shield.

3. The laser cutting tool with protective enclosure assembly according to claim 2, wherein:
said light shield is a semi-translucent shield permitting visual observation within said cavity.

4. The laser cutting tool with protective enclosure assembly according to claim 1, wherein:
said middle protection shield is mounted to said frame via its contact with a shield interlock switch of said safety interlock assembly.

5. The laser cutting tool with protective enclosure assembly according to claim 4, wherein:
said shield interlock switch is in a locked position when said middle protection shield is mounted to said frame, and is switched to an unlocked position when said middle protection shield is detached from said frame;
wherein said laser torch head can be activated only if said shield interlock switches is in said locked position.

6. The laser cutting tool with protective enclosure assembly according to claim 1, wherein:
said top protection assembly comprises a top cover having a top cover opening;

a top brush assembly; and wherein said top brush assembly covers said top cover opening, so as to prevent leaking of any laser light from said cavity.

7. The laser cutting tool with protective enclosure assembly according to claim 6, wherein:
said top brush assembly comprises at least one pair of brush holders having a first brush folder and a second brush holder; and at least one pair of top brushes having a first top brush and a second brush;

wherein one end of said first top brush is received by said first brush holder, and one end of said second top brush is received by said second brush holder.

8. The laser cutting tool with protective enclosure assembly according to claim 7, wherein:
said first top brush and said second top brush are positioned in an opposite direction at the same vertical level, so as to permit a first free distal end of said first top brush which is not received by said first brush holders facing and contacting a second free distal end of said second top brush which is not received by said second brush holders.

9. The laser cutting tool with protective enclosure assembly according to claim 7, wherein:
said top brush assembly further comprises a bracket, wherein said at least one pair of brush holders are mounted to said bracket.

10. The laser cutting tool with protective enclosure assembly according to claim 6, wherein:
said top protection assembly permitting any cables connected to said laser torch head passing through said top protection assembly, wherein said cable operatively moves upward and downward freely without congesting said top protection assembly.

11. The laser cutting tool with protective enclosure assembly according to claim 10, wherein:
said top protection assembly extends to a back of said protective enclosure assembly so as to permit additional vertical travel of said laser torch head and said cable.

12. The laser cutting tool with protective enclosure assembly according to claim 1, wherein:
said frame comprises at least one top interlock switch, said top interlock switch being integral to said safety interlock assembly;
wherein said top interlock switch is in a locked position when said top protection assembly is mounted to said frame and said top interlock position is in an unlocked position when said top protection assembly is removed from said frame; and wherein said laser torch head can be activated only if said at least one top interlock switches is in said locked position.

13. The laser cutting tool with protective enclosure assembly according to claim 12, wherein:
said frame comprises at least one bottom interlock switch, said bottom interlock switch being integral to said safety interlock assembly;
wherein said bottom interlock switch is in a locked position when said bottom protection assembly is mounted to said frame and said bottom interlock position is in an unlocked position when said bottom protection assembly is removed from said frame wherein said laser torch head is deactivated if any of said at least one bottom interlock switches is in said unlocked position.

14. The laser cutting tool with protective enclosure assembly according to claim 12, wherein:
wherein said laser torch head is mounted on an intermediate vertical actuator;

and wherein said intermediate vertical actuator is located inside said protective enclosure assembly and is configured to manipulate the distance between said workpiece and said laser torch head independent of a vertical location of said protective enclosure.

15. The laser cutting tool with protective enclosure assembly according to claim 1, wherein:
said bottom protection assembly comprises:
a bottom cover having an opening;
a bottom brushes cup assembly surrounding said opening so as to permitting said laser torch head extending therethrough.

16. The laser cutting tool with protective enclosure assembly according to claim 1, said bottom protection assembly is configured to safely break away from a remainder of said protective enclosure without permanent damage.

17. A method for assembling a laser cutting tool with protective enclosure assembly, said method comprising steps of:
operatively mounting a frame to a bridge above a workpiece;
removably connecting a top protection assembly to said frame, so as to switch at least one top interlock switch into a locked position;
removably connecting a middle protection shield to said frame, so as to switch at least one shield interlock switch into a locked position;
removably connecting a bottom protection assembly to said frame, so as to switch at least one bottom interlock switch into a locked position; and integrating said top interlock switch, said shield interlock switch and said bottom interlock switch with a safety interlock assembly.

18. The method for assembling a laser cutting tool with protective enclosure assembly according to claim 17, wherein:

said method further comprising arranging a laser torch head within a cavity formed by said frame, said top protection assembly, said middle protection shield, and said bottom protection assembly, wherein said laser torch head can be activated only if all of said top interlock switch, shield interlock switch, and bottom interlock switch of said safety interlock assembly are in said locked position.

19. The method for assembling a laser cutting tool with protective enclosure assembly according to claim 17, wherein:
said top protection assembly comprises:
a top cover having a top cover opening;
a top brush assembly;
wherein said top brush assembly covers said top cover opening, so as to prevent leaking of any laser light from said top protection assembly.

20. A laser cutting tool for manipulating a metal workpiece, said laser cutting tool comprising:
a laser;
a protection assembly disposed about said laser and defining a laser cavity, said protection assembly permitting radiation from said laser to be selectively directed to said workpiece;
wherein said protection assembly includes an aperture permitting access to said laser cavity;
a safety interlock assembly for selectively permitting activation of said laser;
a brush assembly position to cover said aperture, said brush assembly permitting passage of solid objects therethrough, while preventing light from said laser from emanating from said aperture; and wherein said brush assembly is releasably connected to said protection assembly and configured to safely break away from said protection assembly.