Robotic laser tire mold cleaning system and method of use

ABSTRACT

A cleaning device () for removing residual material from a mold () having a molding surface () includes a robot () including an arm () movable in a plurality of degrees of freedom, the arm having a free end. A laser () is connected with the robot () and has an output end mounted to the arm () proximal to the free end so as to be positionable by the robot. An optical delivery system () includes a plurality of optical fibers, each fiber having a first end connected with the laser () and a second, output end attached to the free end of the arm of the robot (). The output ends of the optical fibers () are aligned such that the laser forms a stripe of light () on the molding surface (). A controller () is connected with the robot () and is configured to direct the robotic arm () through at least one predetermined set of movements. A rotatable support () is disposed proximal to the robot () the mold () being disposed on the support. The robot () positions the output end of the laser () with respect to the molding surface () to direct light () from the laser to impinge on the surface and remove residual material from the surface as rotation of the support () aligns different sections of the molding surface with the output end of the laser.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenience only and is not limiting. Referring now to the drawing, wherein like numerals are used to indicate like elements throughout, there is shown in FIG. through FIG. 6 (FIGS. 1-6) a presently preferred embodiment of a robotic laser cleaning device for cleaning residual material from the molding surface of a tire mold . The cleaning device primarily comprises a robot having an arm movable within a plurality of degrees of freedom and a laser connected with the robot and having an output end attached to the free end of the arm of the robot . The robot positions the output end of the laser with respect to the molding surface such that activation of laser directs laser light to impinge on the surface and remove residual material from the surface .

Referring to FIGS. 1 and 2, the robot is preferably a commercially available industrial robot having an arm that is movable within six degrees of freedom (“DOF”). More specifically, the robot preferably includes a base configured to rotate within a horizontal plane (first DOF), to which mounted a “shoulder” of the robotic arm . The robotic arm further includes an “upper arm” having a lower end pivotally attached (second DOF) to the shoulder by means of a laterally extending shaft . The arm also includes a “forearm” having a first end pivotally attached (third DOF) to the free end of the upper arm by means of a pivot shaft . The forearm is pivoted about shaft by movement of actuator arm pivotably connected at end to forearm and at end to shoulder . Further, a “wrist” of the arm is attached to the free end of the forearm and is capable of moving in the following three manners: by pivoting about the free end of the forearm (fourth DOF), by “spinning” about an axis extending along the centerline of the forearm (fifth DOF), and by spinning about the axis (sixth DOF).

Furthermore, the robotic arm includes an “end effector” mounted to the wrist , which is preferably a laser delivery head as described hereinafter. As is well known in the robotics field of art, an end effector is the working tool that is positionable by movement of the robotic arm within one or more of the degrees of freedom.

Preferably, the robot includes a plurality of electric servomotors (not shown) actuating and controlling the movement of the base and the various portions of the arm described above. However, it is within the scope of the present invention to utilize any other appropriate means for actuating the movements of the components of the robot , such as for example, hydraulic or pneumatic motors (neither shown).

Furthermore, although the above-described structure of the robot is preferred, it is within the scope of the present invention to construct the robot in any other manner that enables the robotic laser cleaning device to function as described in detail below. For example, the robot can alternatively have a wrist that is configured to spin, to rotate within a vertical plane, and to rotate in horizontal plane as opposed to spinning along axis . Further, the robot may optionally include a machine vision system provided by, for example, video cameras (none shown) connected to a video processor (not shown), so that the robot can recognize the location of the end effector and adjust its position to ensure that the cleaning device performs as desired during a cleaning operation, as described below.

Preferably, the laser is a standard, solid-state Nd:YAG (i.e., Neodymium doped Yttrium Aluminum Garnet) continuous wave laser, which are well known in the laser field of art. Most preferably, the laser is a commercially available Nd:YAG laser. The laser has sufficient power/intensity such that laser light emitted from the output end of the laser vaporizes residual material in the tire mold upon contact. Although a Nd:YAG laser is preferred, it is within the scope of the present invention for the laser to be a pulsed CO2 laser, a pulsed excimer laser, or any other appropriate type of laser that enables the cleaning device to function as described in the present disclosure. Further, the term “laser” as used in the present disclosure is intended to cover any high-energy irradiation source, including pulsed or continuous wave lasers and high-energy lamps.

As shown in FIG. 3, the laser is mounted on the robot , and is most preferably enclosed within a housing section of the forearm of the robotic arm . However, the laser can alternatively be mounted on a separate platform (not shown) located proximal to the robot or can be mounted at any other appropriate location on the robot , such as for example, in the base . A standard power supply (not shown) connected with the laser provides power to operate the laser and is also preferably mounted on a separate platform (not shown) located proximal to the robot .

Further, as best shown in FIG. 3, the laser includes an optical delivery system having a pathway extending between the laser and the terminal end of the delivery head . In an embodiment shown in FIG. 3, a first end of optical fibers are connected with the laser and a second end of the optical fibers are mounted to the wrist of the robotic arm . Preferably, the delivery system includes a plurality of optical fibers extending from the output port of the laser to the delivery head attached to the wrist at the free end of the robotic arm . The end effector of the robot , as mentioned above, is actually the combination of the delivery head and the output ends of the optical fibers enclosed within the delivery head . The optical fibers are bundled together and disposed within the forearm of the robotic arm so as to extend along the axis of the forearm to the wrist and terminate in the delivery head . Preferably, the delivery head is a tubular housing having a first end attached to the wrist , through which the optical fibers enter the delivery head , and a second or “delivery” end out of which is directed laser light emitted from the output ends of the optical fibers . The tubular housing is preferably curved to facilitate placement of laser light onto complex surfaces of the mold . Furthermore, a vacuum device or “smoke sucker” (not shown) is preferably mounted to the delivery head so as to evacuate residual material vaporized during a cleaning operation through the tubular housing , as described below.

Referring to FIGS. 4, and , the output ends of the optical fibers are aligned such that laser light outputted from the laser forms a stripe of light . Most preferably, the diameter “d” of the optical fibers and the spacing distance “s” between the individual fibers is such that a stripe of light having a length in the range of about 1.92 centimeters (cm) [0.75 inches] to about 3.81 cm [1.5 inches]. The width of the stripe of light is in the range of about 0.25 cm (0.098 inches] to about 1.5 cm [0.394 inches] and is formed on a mold surface from a stand-off distance ds (i.e., the distance from the output ends of the fibers to the mold surface ) of about 1.92 cm to about 3.81 cm. The robot is preferably programmed to ensure that the output ends of the fibers are always normal to the section of the molding surface upon which the stripe is projected, so that the light stripe is of a sufficient intensity to ablate residual material, as described further below.

Although a plurality of optical fibers are preferred, the delivery system may alternatively be provided by a series or optical reflectors, such as mirrors and as shown in FIG. 7, mounted on or within the tubular housing of delivery head and configured to direct laser light from the wrist of the robotic arm , to which it can be delivered through optical fibers , as shown in FIG. 3, and then to a desired target, such as the molding surface of a tire mold . Further, it is within the scope of the present invention to utilize any other appropriate system for delivering laser light from the laser to an end effector (i.e., some type of laser delivery head) of the robotic arm and therefrom to a desired target.

Referring to FIGS. 1 and 2, the robotic laser cleaning device further includes a controller for controlling the operation of the robot and for interfacing the robot operation with the laser . During a cleaning operation (described below), the controller directs the robotic arm so that the delivery head is moved through at least one predetermined set of movements with respect to the tire mold . The predetermined set of movements causes laser light directed from the head to impinge on all sections of the molding surface . The controller also controls the activation and deactivation of the laser so that the laser is turned on and off at appropriate times during the cleaning operation. Further, the controller is fully programmable so as to be capable of actuating the robotic arm to move through a plurality of different predetermined sets of movements. Such controller programmability allows the cleaning device to be used with various molds having different sizes and/or shapes. The controller is preferably the standard control system provided with a commercially available robot , although the controller can alternatively be a separately provided personal computer, a programmable logic controller (“PLC”) or any other such programmable device (none shown) connected with the robot and with the laser .

Referring to FIGS. 1 and 2, the robotic laser cleaning device preferably further includes at least one rotatable support configured to both locate the mold in a specific position with respect to the robot and to rotate the mold with respect to the robot . The rotatable support preferably includes a rotary table rotatably mounted to a stationary base so as to turn about a vertical axis , although another rotatable device such as a cylindrical platform (not shown) may alternatively be used. Further, a centering apparatus (not shown) connected with the rotatable support centers a tire mold placed upon the table about the axis and is preferably provided by three centering guide members (none shown) slidably attached to the table and movable in radial directions. A servomotor (not shown) drives the rotary table and is preferably controlled by the controller , although alternatively the servomotor can be controlled by a separate controller (not shown) or by a manually operated switch and speed control (neither shown). The controller regulates the speed at which the servomotor rotates the support , and thus a mold on the table , and coordinates the rotation of the table with movement of the robotic arm , as described further below.

By having a rotatable support , the cleaning device is able to operate by using the table to rotate the mold about the delivery head , the rotation of the table aligning different circumferential sections of the molding surface with the output ends of the optical fibers . Thus, rotation of the table enables the laser stripe to sweep around the entire circumference of the molding surface . Without a rotatable support, the robotic arm would be required to rotate the head about the central axis so that the laser stripe reaches all sections of the molding surface . Thus, the additional degree of freedom provided by the rotatable support minimizes the amount of twisting and turning required by the robotic arm and thereby reduces the potential for damage to the cleaning device , especially to the optical fibers . However, although it is less desirable, it is within the scope of the present invention to utilize the cleaning device with a stationary support (not shown) for the mold . Further, as shown in FIG. 1, the cleaning device preferably includes a second rotatable support disposed adjacent to the robot such that the two supports and are spaced generally equidistant from the robot . With two supports , , a cleaned mold can be removed from one support or and replaced with another mold to be cleaned while the cleaning device is performing a cleaning operation on a mold disposed on the other support or .

In operation, the robotic laser cleaning device is most preferably used to remove residual material remaining in a tire mold after a tire molding operation is performed. Such material includes particles of uncured and cured rubber, bladder release agents, and other foreign materials such as dust, dirt particles, oils or lubricants from associated manufacturing equipment. However, it is within the scope of the present invention to utilize the cleaning device to remove other residual materials from any other type of mold, such as injection molding equipment (not shown), or from any other manufacturing equipment constructed of a material suitable to be cleaned by laser light.

Generally, the cleaning device operates by rotating the table to turn the mold while, simultaneously, the robot positions and repositions the delivery head so that the laser stripe impinges on every section of the molding surface to remove all residual material from the mold . More specifically, the first step in using the cleaning device is to place a tire mold one or both rotatable supports and , and then center the mold on the rotary table about the axis . When the mold is centered about the axis , the controller is programmed to “know” the location of the entire molding surface of the mold , and can thereby accurately position the robotic arm within the tire mold . The controller activates the robot so that the delivery head is placed within the interior of the tire mold at an initial position with respect to the molding surface . The controller thereafter activates the laser and rotates the rotary table so that the mold turns about the axis , and thus the delivery head , at a rotational speed preferably between about 0.5 rotations per minute (“rpm”) and about 6.0 rpm. The robotic arm executes a predetermined set of movements such that the delivery head directs the light stripe to impinge on all sections of the molding surface . As the light stripe impinges on the molding surface , the stripe contacts any residual material thereupon and causes the material to become vaporized. The vaporized material can then be evacuated from the mold by the smoke sucker (not shown). Preferably, the mold is completely cleaned of residual material from one “pass” of the light stripe over the entire molding surface . However, the cleaning process can be repeated if necessary, such as if a thick accumulation of residual material is initially present on the molding surface .

The cleaning device of the present invention has a number of advantages over prior art mold cleaning systems. For example, by being mounted to a robot , the laser cleaning process is fully automated and therefore operator error, due to such factors as fatigue and/or carelessness, is virtually eliminated. Thus, a tire mold cleaned by the device of the present invention is much more likely to be free of residual materials than a mold cleaned using the hand-held laser system disclosed in the 5,373,140 patent to, Nagy. Further, by having the rotatable support , , wear on the optical fibers that occurs with the Nagy device is not present with the robotic laser cleaning device . Further, the cleaning system is quieter than cleaning systems using CO2 pellets. Further, as the laser light cleans the molding surface in a non-abrasive manner, the life of a mold cleaned by the cleaning device of the present invention is treater than with molds repeatedly cleaned by an existing abrasive process such as those involving impact by glass or plastic beads, or metal shot.

It will he appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the scope of the present invention as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the detailed description of the preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown in the drawings wherein:

FIG. 1 is a top plan view of the robotic laser cleaning device in accordance with the present invention;

FIG. 2 is a side elevational view of the robot and a tire mold on one rotatable support, shown performing a cleaning operation;

FIG. 3 is an enlarged, partially broken-away side view of the forearm and wrist portions of the robotic arm;

FIG. 4 is a greatly enlarged side cross-sectional view of the laser delivery head;

FIG. 5 is a view through line — of FIG. 4;

FIG. 6 is an enlarged, broken-away perspective view of the end of the delivery head and a section of the molding surface, showing an exemplary laser radiation stripe; and

FIG. 7 is a view of an alternate embodiment of the laser delivery head incorporating optical reflectors in accordance with the invention.

CLAIMS

1. A cleaning system (10) for removing residual material from a mold (12) having a molding surface (13), the system including a robot (14) including an arm (16) movable in a plurality of degrees of freedom, the arm having a free end (28b), a laser (18) connected with the robot and having an output end (19) mounted to the arm proximal to the free end so as to be positionable by the robot wherein the robot positions a cleaning system output end (20) with respect to the molding surface to direct radiation (18a) from the laser to impinge on the molding surface and remove residual material from the surface, the output end of the laser enclosed in a laser delivery head (32) containing one or more optical fibers (42) to deliver the laser radiation to a delivery end (44b) of the laser delivery head, the cleaning system characterized by: a plurality of the optical fibers extending from the output end of the laser, through the laser delivery head, to output ends (43) of the fibers located at the delivery end of the laser delivery head; and the output ends of the plurality of optical fibers being aligned and spaced apart such that the laser radiation output from the plurality of optical fibers forms a stripe (18b) of radiation on the molding surface, the system output end (20) disposed to move to the molding surface wherein the direction of movement of the stripe is parallel to the axis of the stripe of radiation.

2. The cleaning system as recited in claim 1 characterized by: a programmable controller (46) connected to control the robot and configured to direct the arm of the robot through at least one predetermined set of movements.

3. The cleaning system as recited in claim 2 characterized in that: the controller is configured to interface the laser with the robot.

4. The cleaning system as recited in claim 1 characterized in that: the laser delivery head is curved so that the laser radiation output can be projected in a direction normal to the molding surfaces to be cleaned using standard motions of the robot.

5. The cleaning system as recited in claim 1 characterized in that: the laser delivery head further includes a plurality of optical deflectors (92, 94) positioned following the output ends of the plurality of fibers to further direct laser radiation from the plurality of optical fibers to the molding surfaces to be cleaned.

6. The cleaning system as recited in claim 1 characterized in that: the diameter (d) of each one of the plurality of optical fibers and the spacing distance (s) between adjacent ones of the plurality of optical fibers is such that the stripe of radiation has a length in a range of 1.92 cm to 3.81 cm, and a width in a range of 0.25 cm to 1.5 cm; wherein the stripe of radiation is formed on the mold surface from a stand-off distance (ds) in a range of 1.92 cm to 3.81 cm.

7. A method of cleaning residual material from the molding surface (13) of a mold (12), the method including: providing a laser (18) having a laser delivery head (32) with a delivery end (44b); moving the laser delivery head to align the delivery end of the laser delivery head with the molding surface; activating the laser such that laser radiation (18a) impinges on the molding surface and removes residual material disposed on the molding surface, the method characterized by: forming the laser radiation impinging on the molding surface into a stripe (18b) of radiation; moving the stripe of radiation relative to the molding surface in a direction which is parallel to the axis of the stripe of radiation; and curving the laser delivery head and moving the laser delivery head in a way that maintains a direction for the radiation which is normal to the molding surface.

8. The method as recited in claim 7 including: providing a robot (14) having an arm (16) movable in a plurality of degrees of freedom; connecting the laser with the robot; mounting the laser delivery head to the arm; and automatically moving the arm of the robot to align the delivery end of the laser delivery head with the molding surface; characterized by: directing the robot to move the laser delivery head through a set of movements predetermined for each unique mold shape, so that the laser radiation is directed to different sections of the molding surface.

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