EP0739260A1

EP0739260A1 - Double x-y table system for use with a fixed beam laser system

Info

Publication number: EP0739260A1
Application number: EP95937530A
Authority: EP
Inventors: William E. Lawson
Original assignee: Laser Machining Inc
Current assignee: Laser Machining Inc
Priority date: 1994-10-18
Filing date: 1995-10-10
Publication date: 1996-10-30
Also published as: AU3961795A; WO1996011769A1; CA2179064A1; JPH09506827A

Abstract

A laser beam machining device includes first and second movable X-Y tables (16, 18) and a stationary beam delivery system (12, 120, 122, 124, 132, 134) for delivering a plurality of fixed path laser beams for machining workpieces (78) on the tables. Workpieces on the first table are machined while workpieces on the second table are loaded or unloaded.

Description

DOUBLE X-Y TABLE SYSTEM FOR USE WITH A FIXED BEAM LASER SYSTEM

BACKGROUND OF THE INVENTION The present invention relates generally to a table system for use with a laser system. More particularly, the present invention relates to a double X-Y table system for use with a fixed beam laser system.

Laser systems have an laser source for producing a laser beam. The laser systems typically also have mirrors and lenses to guide the laser beam to a workpiece. For the laser system to accurately process the workpiece, the mirrors and lenses must be precisely aligned. Maintaining the precise alignment of the mirrors and lenses is simplified when the laser beam is retained in a desired position and the workpiece is moved to the laser beam. Such a device is known as a fixed beam laser system. Because of the costs associated with purchasing and maintaining the laser system, it is desirable to maximize the usage of the laser system. With a single table fixed beam laser system, the laser can typically be utilized for processing operations approximately 50 percent of the time because of the downtime associated with placing and removing workpieces from the table.

One common method for increasing utilization of the laser beam is by placing a switch at an intermediate point in the path of the laser beam. The switch allows the laser beam to be directed along two or more alternate paths to process workpieces located on separate X-Y table systems that are each mounted on a separate base. Inserting the switch into the path of the laser beam allows the laser utilization to be increased to greater than 85 percent.

When the switch is inserted into the path of the laser beam, the distance between the laser source and the workpieces is lengthened. The distance between the laser source and the workpiece plays an increasingly important role as the power of the laser beam is increased. For example, when the laser beam has a power that is greater than about 2000 watts, it becomes considerably more difficult to accurately switch the laser beam because the laser beam varies to a substantial degree as the distance between the laser source and the workpiece is increased. As a result, it is desirable to maintain the distance between the laser source and the workpiece at the smallest possible value.

It also becomes more difficult to accurately switch laser beams to process different workpieces located on separate X-Y table systems when multiple beam laser systems are used. For example, with three or four beam laser systems, it is complicated to switch each of the laser beams so that the laser beams can be used to simultaneously process multiple workpieces located on the separate X-Y table systems. Furthermore, the additional components, which are required to split laser beams for processing on the separate X-Y table systems, necessitate that the laser system occupy additional floor space.

SUMMARY OF THE INVENTION The present invention includes a double X-Y table system for use with a laser system. The laser system includes a fixed path laser beam. The X-Y table system includes a plurality of tables for positioning workpieces relative to the fixed path laser beam. Each of the tables is mounted for selective movement relative to the fixed path laser beam. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a laser system of the present invention. Figure 2 is a top plan view of the laser system.

Figure 3 is another top plan view of the laser system. Figure 4 is yet another top plan view of the laser system. Figure 5 is a top plan view of the laser system with a curtain- type protective shield installed around a processing area. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A laser system according to the present invention is generally illustrated at 10 in Figure 1. The laser system 10 includes a double X-Y table system 14 and at least one laser source 12 for producing at least one fixed path laser beam. The double X-Y table system 14 includes a plurality of tables 16, 18 that are movablv mounted in relation to a base 20. The movable mounting of the tables 16, 18 allows the tables 16, 18 to be selectively positioned in the path of the fixed path laser beam.

By moving the tables 16, 18 with relation to the fixed path laser beam, the laser system 10 of the present invention exhibits several advantages. For example, the laser system 10 allows workpieces on one of the tables to be replaced while the workpieces on the other table are processed. Accordingly, the laser system 10 allows the utilization of the laser beam to be maximized similar to the prior art laser systems that employ switches. However, unlike the prior art laser systems that use switches, the laser system 10 of the present invention does not require complex systems of mirrors and lens to increase the utilization. By moving the workpieces to the laser beam, the laser system

10 of the present invention also enables the distance from the laser source to the workpiece to be maintained at the smallest possible value. Thus, laser beam variation, which is associated with greater distances between the laser source and the workpiece, is minimized. Accordingly, the laser system 10 of the present invention allows for more accurate and cost efficient processing of workpieces.

The prior art switched beam laser systems, which obtain similar utilization rates to the laser system 10 of the present invention, mount each of the tables on a separate base. As a result of mounting both of the tables 16, 18 on one base 20, the laser system 10 of the present invention also enables the area required for installation of the laser system 10 to be reduced. While the laser system 10 of the present invention is described as using a single base, it is also possible to use other mechanisms to position the workpieces with relation to the fixed path laser beam. For example, the tables 16, 18 can be mounted on separate bases that allow the tables to move to a cantilevered position for processing of the workpieces by the fixed path laser beam.

The base 20 is preferably constructed from welded steel. The welded steel construction enables the base 20 to provide stable support for the tables 16, 18 and allows the tables 16, 18 to be accurately moved with respect to the base 20. The base 20 may also be constructed from cast concrete or epoxy aggregate.

The movement of the tables 16, 18 with respect to the base 20 is defined in terms of an X-Y plane. The tables 16, 18 preferably include base portions 60, 62 and surface portions 64, 66. Movement of the base portions 60, 62 with respect to the base 20 allows the position of the surface portions 64, 66 to be adjusted along the X-axis. Movement of the surface portions 64, 66 with respect to the base portions 60, 62 allows the position of the surface portions 64, 66 to be adjusted along the Y-axis.

Movement of the base portions 60, 62 along the X-axis is accomplished using a first guide mechanism. Preferably, the first guide mechanism includes a plurality of rails 40, 42. The first guide mechanism also includes a plurality of ball screw mechanisms 67, 69 to allow each of the base portions 60, 62 to be moved independently along the X-axis. The plurality of rails 40,42 are mounted in parallel relation on the base 20. Each of the rails 40, 42 preferably spans a length of the base 20. Because of the accuracy desired to be obtained by the laser system 10, the rails 40, 42 are precisely aligned. The ball screw mechanisms 67, 69 include a ball mechanism

(not shown) that is mounted to a lower surface of each base portions 60, 62. The ball screw mechanism 67, 69 also includes threaded screws 50, 52 that are each mounted to the base 20. Rotation of each of the threaded screws 50. 52 is preferably controlled by a rotational motor 54, 56. respectively. By separately controlling the rotation of each of the rotational motors 54. 56. the position of the base portions 60, 62 is independently adjusted along the X-axis.

The base portions 60, 62 are preferably formed from a bonded honeycomb structure. The bonded honeycomb structure is preferred because the bonded honeycomb structure has a relatively low weight per area and a high stiffness. These characteristics enable the base portions 60, 62 to provide stable support for the surface portions 64, 66.

The base portions 60, 62 include a plurality of ball bushings 68 that are mounted on a lower surface of each of the base portions 60, 62. The ball bushings 68 provide for low-friction movement of the base portions 60, 62 along the rails 40, 42. Because the accuracy of the movement of the tables 16, 18 is extremely important to accurately process the workpieces, the ball bushings 68 must provide for accurate movement of the base portions 60, 62 along the rails 40, 42. Preferably, the ball bushings 68 are provided proximate to each of the corners of the base portions 60, 62. However, where the base portions 60, 62 are of a large dimension, it may be desirable to provide additional ball bushings 68 at intermediate positions along the base portions 60, 62.

Movement of the surface portions 64, 66 along the Y-axis is accomplished using a plurality of second guide mechanisms that allow the surface portions 64, 66 to be independently moved along the Y-axis.

Preferably, the second guide mechanisms includes a plurality of rails 70, 72,

74, 76 and a plurality of ball screw mechanisms 77, 79.

A first plurality of rails 70, 72 are mounted in parallel relation on the first base portion 60. A second plurality of rails 74, 76 is mounted in parallel relation on the second base portion 62. Each of the rails 70, 72, 74, 76 preferably spans a length of the base portions 60, 62. Because of the accuracy desired to be obtained by the laser system 10, the rails 70, 72, 74, 76 are precisely aligned.

The ball screw mechanisms 77, 79 include a ball mechanism (not shown). The ball mechanisms are mounted to a lower surface of each surface portion 64, 66. The ball screw mechanism 77, 79 also includes threaded screws 80, 82. A separate threaded screw 80, 82 is provided for each ball mechanism so as to enable the surface portions 64, 66 to independently move along the Y-axis. Rotation of each of the threaded screws 80, 82 is preferably controlled by a rotational motor 84, 86, respectively.

The surface portions 64, 66 are preferably formed from sheets of aluminum that are each about approximately 1 inch thick. The sheets of aluminum enable the surface portions 64, 66 to provide stable support for the workpieces 78.

The surface portions 64, 66 include a plurality of ball bushings 88 that are mounted on a lower surface of the surface portions 64, 66. The ball bushings 88 provide for low-friction movement of the surface portion 64 along the rails 70, 72 and surface portion 66 along the rails 74, 76. Because the accuracy of the movement of the tables 16, 18 is extremely important to accurately process the workpieces, the ball bushings 88 must provide for accurate movement of the surface portions 64, 66 along the rails 70, 72, 74, 76.

Preferably, the ball bushings 88 are provided proximate to each of the corners of the surface portions 64, 66. However, where the surface portions 64, 66 are of a large dimension, it may be desirable to provide additional ball bushings 88 at intermediate positions along the surface portions 64, 66.

Preferably, the laser system 10 also includes a mechanism that protect the rails 40, 42, 70, 72, 74, 76 and the threaded screws 50, 52, 80, 82 are contamination by debris that is generated during the processing of the workpieces. A number of rail and threaded screw protection mechanisms are known in the art. One such protection mechanism, which is commonly referred to as a way cover, is described in U.S. Patent No. 5,171,002.

A variety of mechanisms are known in the art to retain workpieces 78 in a desired position while the workpieces 78 are processed with the laser system 10. In addition to retaining the workpieces 78 in a desired position during processing, the mechanisms may also provide the capability to exhaust particles or fumes created by the processing. Suitable workpiece retaining mechanisms include non-metallic honeycombs, knife edges, and toad stools.

Operation control panels 94, 96 are preferably mounted along a front edge 92 of each of the surface portions 64, 66. The operation control panels 94, 96 enable an operator to start, stop, and interrupt a processing cycle. Other features, such as emergency stop, are also suitable for inclusion on the operation control panels 94, 96. Mounting of the operation control panels 94, 96 along the front edge 92 of the surface portions 64, 66 enables the operator to readily access the control panel when operating the laser system 10. As an alternative to mounting the operation control panels 94, 96 on the surface portions 64, 66, the operation control panels 94, 96 may be included in a main controller unit 98, which is adjacent to the laser system 10.

While the system of the present invention is suitable for use with other laser sources, the laser sources 12 are preferably either CO, or YAG lasers. However, other types of lasers are suitable for use with the laser system of the present invention. The laser system 10 is particularly suitable for use with lasers having powers of up to 10,000 watts.

The Figures illustrate that the laser system 10 includes three laser sources 12. However, the selection of the number of laser sources 12 is based upon the desired processing operation. The laser system 10 may also use a single laser source that is split into multiple beams.

The laser sources 12 are supported using a beam delivery support 100. The beam delivery support 100 retains the laser sources 12 in a stationary relationship to the base 20. The stationary relationship between the beam delivery support 100 and the base 20 enables the laser system 10 of the present invention to accurately process the workpieces.

The stationary relationship between the beam delivery support 100 and the base 20 allows the laser beam to be delivered along a vertical path that remains constant throughout the processing operations. Because the laser beam of the present invention are delivered along a constant vertical path, the laser beam is referred to as a fixed path laser beam. The constant vertical path of the laser beam enables the process of aligning the laser beam to be simplified as compared to laser beams that are projected along paths that change. The beam delivery support 100 preferably includes a vertically oriented portion 102 and a horizontally oriented portion 104, which is mounted at an upper end of the vertically oriented portion 102. The horizontally oriented portion 104 extends over a processing area 126 so that the laser sources 12 can be mounted proximate to the processing area 126. While the beam delivery support 100 is preferably constructed from welded steel components, other materials, such as metals and polymeric composites, are suitable for use in fabricating the beam delivery support 100.

The laser sources 12 are preferably mounted on an upper surface 106 of the horizontal portion 104. As illustrated in Figure 1, a horizontal guide 120 is provided to direct the laser beam until the laser beam is immediately above the laser processing area 126. A reflective mirror or lens 122 is attached to the horizontal guide 120 to reflect the laser beam into a vertical path. A vertical guide 124 is provided to direct the laser beam to an appropriate region where the laser beam can be focused at the workpieces 78. The vertical guide 124 extends through the horizontal portion 104. The laser beam is preferably focused to a focal point 130 using a lens 132.

The laser system 10 may be fitted with a variety of beam delivery mechanisms. For example, Figure 1 illustrates using a transmissive focusing head 134. The transmissive focusing head 134 provides the laser system with the ability to automatically adjust the vertical position of the laser beam focal point 134 to optimize the cutting ability of the laser beam when workpieces 78 having differing thicknesses are processed by the laser system 10. The construction and operation of the transmissive focusing heads 134 that are suitable for use with the present invention are known in the art. The laser system 10 preferably includes power supplies 140 for each of the laser sources 12. The laser system 10 also preferably includes a chiller (not shown) that provides coolant to each of the laser beam sources 12. The coolant prevents the laser sources 12 from overheating. In operation, each of the tables 16, 18 are initially oriented in a loading position as illustrated in Figure 2. When in the loading position, the surface portions 64, 66 and the base portions 60, 62 are positioned entirely outside of the processing area 126, which encompasses the range of motion of the surface portions 64, 66 and the base portions 60, 62 during the laser processing operation. Within the processing area 126, the laser sources 12 are focused at the workpiece 78. The focal point of the laser beam is illustrated at 130 in Figures 2-4. A portion of the laser sources 12 and the beam delivery support 100 has been cut away in Figures 2-4 so that the features and movement on the tables 16, 18 can be more clearly illustrated. Prior to performing the laser processing operation, the controller 98 is programmed so that the laser beams will process the workpieces 78 in a desired manner. While the workpieces 78 on the first table 16 are preferably processed in the same manner as the workpieces 78 on the second table 18, the controller can be programmed to process the workpieces 78 on the first table 16 in a different manner than the workpieces 78 on the second table 18.

The workpieces 78 are loaded on the first surface portion 64 in a desired orientation. The workpieces 78 may be retained in the desired orientation on the first surface portion 64 using a variety of mechanisms that are known in the art. After the operator activates the cycle start button on the first operation control panel 94, the controller 98 instructs the rotational motors 54, 84 to move the first base portion 60 along the X-axis and the first surface portion 64 along to the Y-axis until the first surface portion 64 is positioned in the processing area 126 beneath the focal points 130 of the laser beams as illustrated in Figure 3. The workpieces 78 are then processed by exposure to the laser beams in a desired manner by controlling the position of the first surface portion 64 on the rails 70, 72 by rotation of the rotational motor 54 and the first base portion 60 on the rails 40, 42 by rotation of the rotational motor 54.

As the workpieces 78 on the first surface portion 64 are processed, workpieces 78 are loaded on the second surface portion 66. Similar to the workpieces 78 on the first portion surface 64. the workpieces 78 on the second surface portion 66 may be retained in a desired position using a variety of mechanisms that are known in the art.

After completing processing of the workpieces 78 on the first surface portion 64, the controller 98 instructs the rotational motors 54, 84 to move the first surface portion 64 and the first base portion 60 to the loading position as illustrated in Figure 2. Once the first surface portion 64 and the first base portion 60 are in the loading position, the operator can activate the cycle start button on the second operation control panel 9b. The controller 98 instructs the rotational motors 56, 86 to move the second base portion 62 along the X-axis and the second surface portion 66 along the Y-axis until the second surface portion 66 is positioned in the processing area 126 beneath the focal points 130 of the laser beams as illustrated in Figure 4. The workpieces 78 are then processed by exposure to the laser beams in a desired manner by controlling the position of the second surface portion 66 on the rails 74, 76 and the second base portion 62 on the rails 40, 42 by rotation of the rotational motors 56, 86.

As the workpieces 78 on the second surface portion 66 are processed, processed workpieces are unloaded from the first surface portion 64 and unprocessed workpieces are loaded on the first surface portion 64. After processing of the workpieces 78 on the second surface portion 66 is completed, the controller 98 instructs the rotational motors 56, 86 to move the second surface portion 66 and the first base portion 62 to the loading position. Once the second surface portion 66 and the second base portion 62 are in the loading position, the operator can activate the cycle start button on the first operation control panel 94 to begin processing workpieces 78 on the first surface portion 64. The process may be repeated until all of the workpieces 78 are processed.

While the laser system of the present invention has been described as allowing both tables to be alternatively used to process workpieces, it is also possible to use only one of the tables while maintenance is being performed on the other table. Only using one of the tables would enable use of the laser system while the other table is being changed over so that it can perform a different processing operation on a different shaped workpiece.

For certain processing operations, it is desirable to provide an enclosure 198, as illustrated in Figure 5, to prevent escape of laser radiation or fumes that are emitted during the processing operation so as to protect operators from injury. One such enclosure 198 entails a plurality of curtains that are positioned around the processing area 126. Curtains 202, 204. 206 are positioned along three open sides of the processing area 126. In addition to protecting operators from injury, the operators can remove the curtains 202, 204, 206 to access the double X-Y table system 14 and the laser sources 12. The front curtain 202 is hung in front of the processing area

126. The side curtains 204, 206 are hung in an extended position along the sides of the processing area 126. The hanging of the curtains 204, 206 preferably enables the curtains 204, 206 to be readily moved to a retracted position (not shown) when it is desired to move one of the tables 16, 18 into the processing area 126. Once the table 16, 18 is moved into the processing area 126, the curtain 204, 206 is returned to the extended position. The enclosure thereby formed by the curtains 202, 204, 206 provides sufficient space for the uninterfered movement of the tables 16, 18 along the X-axis and the Y-axis during the processing operation.

The enclosures can also be constructed in the form of a rigid wall if it is desired to provide additional protection to the operator during processing operations that involve a greater risk of injury to the operator. The rigid enclosure can either be formed to enclose the entire laser system 10 or the processing area 126.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS: 1. An apparatus for processing workpieces, the apparatus comprising: a fixed path energy beam; and a support device for positioning each workpiece relative to the fixed path energy beam, the support device comprising a plurality of X-Y tables, each of the X-Y tables being mounted for selective movement relative to the fixed path energy beam.

2. The apparatus of claim 1 wherein the fixed path energy beam is a laser beam.

3. The apparatus of claim 2 wherein the laser beam has a power of between approximately 25 watts and 10,000 watts.

4. The apparatus of claim 1 and further comprising a base being mounted in a stationary relationship to the fixed path energy beam, each of the X-Y tables being movably mounted with relation to the base.

5. The apparatus of claim 1 wherein the plurality of X-Y tables comprises a first X-Y table and a second X-Y table.

6. The apparatus of claim 5 wherein the support device further comprises: a first guide track mounted on the base; a first support movably mounted in working relation to the first guide track; a second guide track mounted to the first support, wherein the second guide track is oriented approximately perpendicular to the first guide track and the first X-Y table is movably mounted to the second guide track for movement along the second guide track; a second support movably mounted in working relation to the first guide track; and a third guide track mounted to the second support, wherein the third guide track is oriented approximately perpendicular to the first guide track and the second X-Y table is movably mounted to the third guide track for movement along the second guide track.

7. An apparatus for processing workpieces, the apparatus comprising: a plurality of fixed path energy beams; and a support device for positioning the workpieces relative to the fixed path energy beams, the support comprising a plurality of X-Y tables, each X-Y table being movably mounted relative to the fixed path energy beams, and each of the X-Y tables being capable of supporting workpieces such that the plurality of fixed path energy beams are capable of simultaneously processing workpieces on each X-Y table.

8. The apparatus of claim 7 wherein the fixed path energy beams are laser beams.

9. The apparatus of claim 8 wherein the laser beams each have a power of between approximately 25 watts and 10,000 watts.

10. The apparatus of claim 7 and further comprising a base being mounted in a stationary relation to the fixed path energy beam, each of the X-Y tables being movably mounted with relation to the base.

11. The apparatus of claim 7 wherein the plurality of X-Y tables comprises a first X-Y table and a second X-Y table.

12. The apparatus of claim 11 wherein the support device further comprises: a first guide track mounted on the base; a first support movably mounted in working relation to the first guide track; a second guide track mounted to the first support, wherein the second guide track is oriented approximately perpendicular to the first guide track and the first X-Y table is movably mounted to the second guide track for movement along the second guide track; a second support movably mounted in working relation to the first guide track; and a third guide track mounted to the second support, wherein the third guide track is oriented approximately perpendicular to the first guide track and wherein the second X-Y table is movably mounted to the third guide track for movement along the third guide track.

13. A method for processing workpieces using a fixed path energy beam, the method comprising: loading a first workpiece on a X-Y first table; moving the first X-Y table to a processing position; processing the first workpiece with the fixed path energy beam; loading a second workpiece on a second X-Y table; moving the first X-Y table from the processing position; moving the second X-Y table to the processing position; processing the second workpiece with the fixed path energy beam; and moving the second X-Y table from the processing position.

14. The method of claim 13 wherein the processing of the first workpiece is substantially identical to the processing of the second workpiece.

15. The method of claim 13 wherein the second X-Y table is positioned in a second loading position while the first workpiece is processed and the first X-Y table is positioned in a first loading position while the second workpiece is processed.

16. A method for processing workpieces using fixed path energy beams, the method comprising: loading a first set of workpieces on a first X-Y table; moving the first X-Y table to a processing position; processing the first set of workpieces with the fixed path energy beams; moving the first X-Y table from the processing position; loading a second set of workpieces on a second X-Y table; moving the second X-Y table to the processing position; processing the second set of workpieces with the fixed path energy beams; and moving the second X-Y table from the processing position.

17. The method of claim 16 wherein the second X-Y table is positioned in a second loading position while the first set of workpieces are processed and the first X-Y table is positioned in a first loading position while the second set of workpieces are processed.