Patent Description:
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.

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.

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.

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.

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

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

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 to exit a typical protective enclosure apparatus.

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.

It is another object of the present invention to provide a protection system for a laser cutting machine having a guard surrounding only the laser torch head, which therefore reduces the overall size of the laser cutting machine.

It is another object of the present invention to provide a protection system for a laser cutting machine that minimizes light reflection from the laser torch head.

Laser cutting systems and a method of outfitting a laser cutting system with protective elements according to the present invention are defined in claims <NUM>, <NUM> and <NUM> respectively.

Further preferred embodiments of the present invention are defined in the appended claims.

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.

An inch corresponds to <NUM> millimetres, a temperature in degrees Celsius (°C) corresponds to (Temperature in degrees Fahrenheit (°F) - <NUM>) * <NUM>/<NUM>. And a pound(lb) corresponds to <NUM>,<NUM> kilogramme.

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

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 <FIG>, 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.

<FIG> illustrates an isomeric, side view of a protection system <NUM>. In particular, <FIG> illustrates the protection system <NUM>, as integrated with a laser torch head <NUM>, a bridge <NUM> for supporting the laser torch head, and a workpiece <NUM> being processed. As it will be appreciated, the laser torch head <NUM>, the bridge <NUM> and the workpiece <NUM> are only partially shown in <FIG>, so as to permit illustration of the protection system itself, and its preferred placement with respect to the bridge <NUM>, the laser torch head <NUM> and the workpiece <NUM>.

While this is being described in connection with the bridge <NUM> and the laser torch head <NUM> shown in <FIG>, it will be readily appreciated by one of ordinary skill in the art that the present protection system <NUM> could be integrated into any laser cutting head, regardless of the specific type of the same.

As most clearly shown in <FIG>, the protection system <NUM> is moveably mounted to the bridge <NUM> so as to move therealong. The bridge <NUM> itself is adapted to move in a direction perpendicular to the moving direction of the protection system <NUM>, so as to cut the workpiece <NUM>, as desired. Additionally, the protection system <NUM> is designed such that the laser cutting head can be mounted on a motorized actuator inside the protection system <NUM> 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.

The protection system <NUM> includes a frame <NUM>, a top protection assembly <NUM>, a middle protection shield <NUM>, and a bottom protection assembly <NUM>, thereby forming a cavity where a laser torch head <NUM> locates, so as to prevent the escaping of reflected laser light when the laser torch head <NUM> cuts the workpiece <NUM>.

As will be appreciated, and in stark contrast to the enclosure of the apparatus shown in <FIG>, it is an important aspect of the present invention that it is only the laser head <NUM> itself, which is enclosed by top, middle and bottom assemblies, <NUM>, <NUM> and <NUM> respectively. Thus, the protection system/enclosure of the present invention does not extend to the apparatus as a whole, nor does the enclosure encompass the movable platen upon which the workpiece is arranged.

Turning now to <FIG> and <FIG>, in combination, the middle protection shield assembly <NUM> of the protection system <NUM> is illustrated in more detail. A light shield <NUM> 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 <NUM>, meanwhile prevents the reflected laser light escaping from the cavity. The light shield includes a planetary gasket <NUM>. The light shield <NUM> is removably fixed to the frame <NUM> via four interlock switches <NUM> embedded in the frame <NUM>. In alternative embodiments, the middle protection shield assembly <NUM> is mounted on hinges or vertical slides which are in conjunction with latches, the planetary gasket <NUM>, and safety interlock switches <NUM>, so as to allow interlocked access to the laser head for maintenance while preventing exposure of the laser by an operator.

In particular, the present invention envisions that the light shield <NUM> 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.

It should be noted that the light shield <NUM> must be secured to the frame <NUM> and the interlock switches <NUM> must be in contact with the light shield <NUM> in order for the laser torch head <NUM> to start working. Indeed, the there are several safety switches integrated with the light shield <NUM>, all of which must be actuated in order for the laser head <NUM> to be permitted to operate.

As shown, <FIG> illustrates the middle protection shield <NUM> in an enclosed position. The light shield <NUM> is secured onto the frame <NUM> via four interlock (safety) switches <NUM>. The interlock switches are in a locked position and therefore permits the laser torch head <NUM> to start working. <FIG>, in contrast, illustrates the middle protection shield <NUM> in an opened position. The light shield <NUM> is removed from the frame <NUM>. The interlock switches trip to an unlocked position upon the detaching of the light shield <NUM> from the frame <NUM>. Therefore, the laser torch head <NUM> is unable to start working until the light shield <NUM> is secured to the frame <NUM> again.

The frame <NUM> is preferably welded so as to provide a continuous housing, thereby preventing radiation from escaping during operation of the laser head <NUM>.

<FIG> and <FIG>, in combination, illustrate a sectional view of the top protection assembly <NUM>. In one preferred embodiment, the top protection assembly <NUM> includes a top support cover <NUM> having an opening, and at least brush assembly <NUM> positioned to cover the opening of the top support cover <NUM>. The brush assembly is connected to the top support cover <NUM> via a bracket <NUM>.

The brush assembly <NUM> includes one pair of brush holders <NUM> which are in connection with the bracket <NUM>, and a pair of brushes <NUM>, each of which comprises a plurality of brush bristles. One end of the brush <NUM> is received by the brush holder <NUM> 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 <NUM> prevents the reflected laser light from escaping the cavity from the top protection assembly <NUM>, meanwhile permits any electrical cable, light cable or power cable connected to the laser torch head <NUM> to pass through the top protection assembly <NUM> and enter into the cavity. The cables therefore can move upward and/or downward freely without congesting the top protection assembly <NUM>.

It shall be noted that in a preferred embodiment, three layers of the brushes assembly <NUM> are arranged vertically and connected to the bracket <NUM>. However, any number of layers can be used to optimize the protection effect of the top protection assembly <NUM>.

The top protection assembly <NUM> is connected to the frame <NUM> via two interlock (safety) switches <NUM>. The two interlock switches <NUM> are in a locked position and permit the laser <NUM> to start working once the top protection assembly <NUM> is correctly fixed to the frame. However, if the top protection assembly <NUM> is removed, the two interlock switches <NUM> trip to an unlocked position and therefore prevent the laser torch head <NUM> from starting. In another embodiment, the top protection assembly <NUM> 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.

<FIG> and <FIG>, in combination, illustrate the bottom protection assembly <NUM>. The bottom protection assembly <NUM> includes a bottom cover <NUM> having an opening to permit the laser torch head <NUM> extending therethrough and applying the laser light onto the workpiece <NUM> via a laser application tip unit <NUM>. The bottom protection assembly <NUM> further includes a bottom brushes cup assembly <NUM>. The bottom cup assembly <NUM> is arranged in a position relative to the opening on the bottom cover <NUM> so as to permit the operation of the laser torch head <NUM> on the workpiece <NUM>.

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

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

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 <NUM>.

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

The safe operation of the laser head <NUM> is further increased by arranging a senor (unillustrated) in the area of the base <NUM>, for the purposes of detecting whether a workpiece is positioned adjacent the laser head <NUM>. If the sensor does not detect a workpiece in the area adjacent to the laser head <NUM>, the laser head <NUM> will not be permitted to operate. Preferably, the laser head <NUM> will be prevented from operating if the sensor does not detect a workpiece within approximately <NUM> below the laser head <NUM>, although it will be readily appreciated that other distances may be instead utilised.

<FIG> illustrates a cut-away of the top and bottom portions of the protective enclosure <NUM>. As shown in <FIG>, the light shield <NUM> and frame <NUM> interact and are sized and positioned such that there is an overlap, <NUM>/<NUM>, between a raised edge of the frame <NUM> and the light shield <NUM>, thus ensuring that extraneous light from the laser head <NUM> does not escape the protective enclosure <NUM>.

<FIG> shows an enlarged bottom portion of the protective enclosure <NUM>, as well as a sectional view of one of a pair of spring-loaded bush biasing devices <NUM>. As illustrated in <FIG>, the bottom brush cup assembly <NUM> includes an upper mounting plate <NUM>, which itself is releasably attached to a base mounting plate <NUM> that is operatively attached to the pair of spring-loaded brush biasing devices <NUM>.

As will be appreciated, the spring-loaded brush biasing devices <NUM> include preferably an articulating ball joint <NUM> and a biasing spring/element <NUM>. The biasing device <NUM> thereby act to allow the brush cup assembly <NUM> 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 <NUM> may comprise a magnetically coupled design to permit the brush biasing devices <NUM> 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 <NUM> will ensure deactivation of the laser in the case of a collision and subsequent separation of the ball joint <NUM>.

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, <FIG> illustrates the brush cup assembly as removed from integration with the lower part of the protective enclosure. As further shown in <FIG>, a safety switch <NUM> may be integrated with the protective enclosure to detect the presence of the brush cup assembly <NUM>. The safety switch <NUM> is preferably a compression limit type switch or coded RFID switch, and is sensitive enough to determine when the bush cup <NUM> 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 <NUM> does not detect the existence and proper installation of the bush cup assembly <NUM>, the laser head <NUM> would be prohibited from operation.

As discussed previously, the protective enclosure of the present invention includes many features that make the safe operation of the laser head <NUM> possible. <FIG> illustrates a close-up sectional view of the bottom protection assembly <NUM>. As shown in <FIG>, and in a preferred embodiment, the bush cup assembly <NUM> includes two concentrically aligned brushes/brush rings <NUM>, each of which includes a solid rubber membrane <NUM> embedded within each of the concentrically aligned brush rings <NUM>.

As will be appreciated, the bushes <NUM> 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 <NUM> is disposed between the brushes <NUM> and the laser head <NUM>, in order to protect the brushes from damage due to operation of the laser head <NUM>. <FIG> shows the non-linear path <NUM> that light emanating from the laser head <NUM> must follow, in order to escape the protective enclosure of the present invention.

As discussed previously, one important aspect of the present invention is that the laser head <NUM> is much more easily accessible than known devices, and this additional functionality is shown in <FIG>. As shown in <FIG>, the light shield <NUM> is movably mounted to linear guides <NUM>, which allow the light shield <NUM> 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 <NUM> are therefore utilized to determine if and when the light shield is in its lowered position, and only allows operation of the laser head <NUM> if the sensors <NUM> agree that the light shield is in the proper, protective (lowered) position.

As will be appreciated from a review drawing <FIG> 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 <NUM> as safe as possible.

It is envisioned that the protection system <NUM> may be incorporated into a variety of laser cutting systems known in the art. <FIG> and <FIG> illustrate one such implementation of the protection system <NUM> with a laser cutting system <NUM>. As shown therein, the laser cutting system <NUM> includes a cutting table or platen <NUM> having a frame <NUM> and a plurality of workpiece support elements <NUM> coupled to the frame for supporting a workpiece, such as workpiece <NUM>. The frame <NUM> comprises according to the present invention a plurality of structural members <NUM> defining a generally rectangular-shaped frame <NUM>. For example, the structural members <NUM> may be formed from steel tubes, although other configurations may be utilized without departing from the broader aspects of the invention. The table <NUM> is preferably a stationary table, although it is envisioned that the system <NUM> may include a movable table or platen. In an embodiment, the table <NUM> may be, for example, any of the cutting tables in the Vulcan® line of cutting systems offered by Mestek Machinery®.

As illustrated in <FIG> and <FIG>, the cutting system <NUM> may further include one or more coil stations <NUM> that receive rolls <NUM> of material for automated feeding onto the table <NUM>. While <FIG> and <FIG> depict a coil fed system, the system <NUM> may alternatively be configured as a sheet fed system.

As discussed above in connection with the protection system <NUM>, the lasers of laser cutting machines are capable of emitting high levels of energy and can therefore be dangerous to the eyes and skin of its operator, and the random reflection of the laser light may be hazardous to operators in the vicinity of the machine. The protection system <NUM> of the present invention, as discussed above, sufficiently encapsulates the laser head so as to prevent or substantially minimize the escape of radiation and light from the laser that could be harmful to persons and structures surrounding the machine.

While the protection system <NUM> described herein substantially prevents the escape of light and radiation above the workpiece, in any direction, laser light and energy that passes through the workpiece <NUM> during the cutting operation is not encapsulated or captured by the protective enclosure of the protection system <NUM>. In particular, light from the laser may pass through the workpiece and reflect off of the frame <NUM>, including the structural members <NUM> and/or the support elements <NUM>. While such light is typically contained beneath the workpiece <NUM> interior to the frame <NUM> of the table <NUM>, such reflected light, over time, can damage the structural members <NUM> and/or the support elements <NUM>. In addition, in some case, the light may reflect off of the frame and escape to the surrounding environment where it may be hazardous. To address this issue, protective panels <NUM> are affixed to some or all of the structural members <NUM> of the frame <NUM>, and optionally also to the workpiece support elements <NUM>. According to the present invention, the protective panels <NUM> are mounted to all structural table members that are located over the effective cutting area. In an embodiment, the protective panels <NUM> may be secured to the structural members <NUM> by rivets, although other fastening means known in the art may also be utilized without departing from the broader aspects of the invention.

The protective panels <NUM> are formed from a material that provides for a high degree of light absorption and minimal reflectivity (to absorb light from the laser head <NUM> and substantially minimize or prevent reflection). For example, in an embodiment, the panels <NUM> are flexible graphite sheets or panels having a thickness between about <NUM>/<NUM> inches and about <NUM>/<NUM> inches. In the preferred embodiment, the flexible graphite sheets have a thickness of approximately <NUM> inches. In one embodiment, the flexible graphite sheets have a density of approximately <NUM> lb/ft3, a maximum service temperature of approximately <NUM>°F, a minimum service temperature of approximately -<NUM>°F, a thermal conductivity (parallel to the surface) of about <NUM> BTU-in/hr-ft °F and a thermal conductivity (normal to the surface) of about <NUM> BTU-in/hr-ft °F. While flexible graphite sheets have been discovered to provide optimal laser light absorption, other materials having similar properties and light absorption characteristics, may also be utilised.

In use, the flexible graphite panels <NUM> on the structural members of the system <NUM>, as discussed above, absorb light from the laser during the cutting operation and does not allow it to reflect. The panels <NUM> also absorb the energy of the laser beam, preventing any residual damage to the structural members of the table <NUM>. In a system incorporating graphite sheets on the structural members of the table, reflectivity of the laser beam has measured at less than <NUM>% of the allowable light recommended by the FDA for fiber lasers. Like the minimalist protective enclosure <NUM>, the protective panels <NUM> do not inhibit free and unobstructed loading and unloading of the workpiece onto and off the table (with existing systems, an operator would have to wait for the pallet shuttle to exit a typical protective enclosure apparatus).

According to a further aspect of the present invention, rather than utilizing protective panels, a protective material is applied to all of the structural members that are located over an effective cutting area of the platen to increase light absorption and minimize reflection. The protective material is, in a preferred embodiment of the present invention, a graphite material that is sprayed on such components. Alternatively, the material may be formulated as a liquid and the components dipped in the material or otherwise coated with the material to impart light absorption properties.

In view of the above, the present invention therefore provides a comprehensive protection system for a laser cutting machine that contains substantially all of the laser light and energy, either within protective enclosure <NUM>, or through absorption using protective panels <NUM> attached to the frame and/or structural members of the table <NUM> supporting the workpiece. Taken together, the protection system of the present invention therefore provides a level of safety and ease of use heretofore not seen in the art.

Claim 1:
A laser cutting system, comprising:
a platen (<NUM>) having a plurality of structural members (<NUM>) defining a frame (<NUM>) configured to receive a workpiece (<NUM>) for a cutting operation;
a laser torch head (<NUM>) movable in relation to the platen (<NUM>) to selectively cut the workpiece (<NUM>);
the laser cutting system being characterised by:
protective panels (<NUM>) mounted to all structural table members that are located over the effective cutting area, the protective panel (<NUM>) being configured to absorb light and energy from the laser torch head (<NUM>) during the cutting operation.