Abstract:
An x-y axis guiding apparatus is utilized as the guiding mechanism for a laser marking device. Wear compensating bearings are utilized in conjunction with the x-y axis guiding apparatus so that the gaps between the bearings and the guide components which occur as the bearings wear is taken up and the desired precision maintained.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a laser marking device which utilizes an x-y axis guiding system. Wear compensating bearings are utilized with the x-y axis guiding apparatus to provide the required precision for a laser marking device. 
     2. Description of the Related Art 
     Laser marking devices are useful to mark serial numbers, trademarks, logos, etc. These markings are made on a variety of workpieces or products including those made from anodized or painted metal, quartz or ceramics. 
     Laser marking devices are commonly utilized to create small and precise marks. Since the marks created by laser marking devices are generally small in size, the system for guiding the laser must be very precise to create a legible mark. Galvo systems are commonly utilized to achieve the required precision guiding in laser marking devices. The galvo guiding systems currently used in the art are very expensive to manufacture and, therefore, laser marking devices utilizing such guiding systems are very expensive. 
     What is needed in the art is a laser marking device which has a precision guiding apparatus and which is less expensive to manufacture than the currently available guiding systems. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to improve upon the currently available laser marking devices, wherein it is desired to provide a laser marking apparatus which can precisely guide a marking laser beam and is less expensive than the currently available guiding systems. 
     The present invention provides a laser marking device which utilizes an x-y axis guiding system to position the marking laser beam along the desired marking path. To achieve the desired precision, wear compensating bearings are utilized in conjunction with the x-y axis guiding system. X-y axis guiding systems are much more cost effective than the galvo guiding systems currently utilized. The wear compensating bearings utilized in conjunction with the x-y axis guiding system utilize tension elements to reduce the inherent gaps between the bearing and the guide created as the bearing wears, while maintaining operative relationship between the guide and the guided part. Such system maintains the center line of the bearing colinear with the center line of shaft about which the bearing surrounds utilizing an application of a radially inward directed compressive force or load. 
     The invention, in one form thereof, comprises a laser marking apparatus for marking the workpiece, wherein the laser beam is operable to travel in a coordinate system which includes an x-axis, a y-axis, and a z-axis. The apparatus of this form of the current invention includes a laser source which is operative to produce a laser beam which travels substantially along the z-axis as it exits the laser source. An x-y axis guiding apparatus is utilized to guide the laser beam. The x-y axis guiding apparatus is moveable along the x-axis and the y-axis and such movement of the x-y axis guiding apparatus is operative to move the laser beam. The laser source can be, for example, without limitation, a CO 2 , YAG, or Pulsed Diode laser source. 
     In one form of the current invention, the x-y axis guiding apparatus includes a first reflective surface which is operably positioned to redirect the laser beam so that it travels substantially along the x-axis. A second reflective surface is operably positioned to redirect the laser beam after the laser beam has been redirected by the first reflective surface. The second reflective surface redirects the laser beam so that it travels substantially along the y-axis. A third reflective surface is utilized to further redirect the laser beam as the laser beam travels substantially along the y-axis. The third reflective surface redirects the laser beam so that it travels substantially along the z-axis. 
     In one form of the current invention, the second reflective surface is affixed to a first guide component while the third reflective surface is affixed to a second guide component. An x-axis guide shaft and a y-axis guide shaft as well as an x-axis actuator and a y-axis actuator are provided. The x-axis and y-axis actuators can be, for example, ball screws, precision timing belts, or cable drive actuators. The x-axis ball screw and the y-axis ball screw are substantially parallel to the x-axis guide shaft and the y-axis guide shaft, respectively. The first guide component is operably connected to the x-axis guide shaft for movement therealong. The first guide component is additionally operably connected to the x-axis ball screw. Similarly, the second guide component is operably connected to the y-axis guide shaft for movement therealong and is operably connected to the y-axis ball screw. The y-axis guide shaft and the y-axis ball screw are both affixed to the first guide component so that movement of the first guide component moves both the y-axis guide shaft and the y-axis ball screw. The x-axis guide shaft and the y-axis guide shaft can be, for example, polished stainless steel shafts. 
     A first bearing is positioned between the x-axis guide shaft and the first guide component, while a second bearing is positioned between the y-axis guide shaft and the second guide component. The first bearing and the second bearing are operative to allow relative movement between the x-axis guide shaft and the first guide component and the y-axis guide shaft and second guide component, respectively. 
     In one form of the current invention, a first drive means is operably connected to the x-axis ball screw and is operative to actuate the x-axis ball screw. Actuation of the x-axis ball screw actuates the first guide component in the x-direction. Similarly, a second drive means is operably connected to the y-axis ball screw. The second drive means is operative to actuate the y-axis ball screw, whereby actuation of the y-axis ball screw actuates the second guide component in the y-direction. The first drive means and second drive means can be, for example, a first stepper motor and a second stepper motor, respectively. 
     In one form of the current invention, a computational device is communicatively connected to a first stepper motor and a second stepper motor. The computational device is operative to control both the first stepper motor and the second stepper motor and, therefore, to control the markings made by the laser. 
     In one form of the current invention, a first biasing means is operatively connected to the first bearing and is operative to maintain the first bearing in operative relationship with the x-axis guide shaft while the first bearing maintains its operative relationship with the first guide component. Similarly, a second biasing means is operatively connected to the second bearing and is operative to maintain the second bearing in operative relationship with the y-axis guide shaft while the second bearing maintains its operative relationship with the second guide component. The first and second biasing means can be, for example, an annular spring or any of various known elastic members. 
     The invention, in another form thereof, comprises a precision guiding apparatus which includes a guide shaft and a guide component. The guide component is operably connected to the guide shaft for movement therealong. A bearing is provided and is operative to allow relative movement between the guide shaft and the guide component. Biasing means surround the bearing always centering the bearing about the guide shaft. The biasing means can be, for example, an annular spring. 
     The invention, in another form thereof, comprises a laser marking apparatus for marking a workpiece with a laser beam. The laser beam is operable to travel in a coordinate system which includes an x-axis, a y-axis, and a z-axis. A laser source is operative to produce a CO 2  laser beam which travels substantially along the z-axis from the laser source. A first reflective surface is operably positioned to redirect the laser beam so that the laser beam travels substantially along the x-axis after being redirected by the first reflective surface. A second reflective surface is affixed to a first guide component. The second reflective surface is operably positioned to redirect the laser beam so that the laser beam travels substantially along the y-axis after being redirected by the second reflective surface. 
     The first guide component is operably connected to an x-axis guide shaft for movement therealong. The x-axis guide shaft is formed from polished stainless steel. A first wear compensating bearing is affixed to the first guide component and contacts the x-axis guide shaft such that the first wear compensating bearing is operative to allow relative movement between the first guide component and the x-axis guide shaft. The first wear compensating bearing has a first end and a second end. The first end of the first wear compensating bearing includes a groove. The first wear compensating bearing has at least one aperture which is elongate in shape and is shorter than the first wear compensating bearing. The aperture has a first end and a second end with the first end of the aperture being flush with the first end of the first wear compensating bearing. Such aperture may be a slot. 
     A first spring means is sized to fit in the groove of the first wear compensating bearing and is designed to maintain the first self-wearing bearing in centered operative contact with the x-axis guide shaft. The first guide component is operably connected to an x-axis ball screw. The x-axis ball screw is operably connected to a first stepper motor which is operative to actuate the x-axis ball screw, whereby actuation of the x-axis ball screw actuates the first guide component in the x-direction. 
     A third reflective surface is affixed to a second guide component and is operably positioned to redirect the laser beam so that the laser beam travels substantially along the z-axis after being redirected by the third reflective surface. A y-axis guide shaft is affixed to the first guide component, while the second guide component is operably connected to the y-axis guide shaft for movement therealong. The y-axis guide shaft is formed from polished stainless steel. 
     A second wear compensating bearing is affixed to the second guide component and contacts the y-axis guide shaft. The second wear compensating bearing is operative to allow relative movement between the second guide component and the y-axis guide shaft. The second wear compensating bearing has a first end and a second end. The first end of the second wear compensating bearing has a groove. The second wear compensating bearing includes at least one aperture. The aperture, such as a slot is elongate in shape and is shorter than the second wear compensating bearing. The aperture has a first end and a second end with the first end of the aperture being flush with the first end of the second wear compensating bearing. 
     A second spring means is sized to fit in the groove of the second wear compensating bearing and is designed to maintain the second self-wearing bearing in centered operative contact with the y-axis guide shaft. A y-axis ball screw is affixed to the first guide component and the second guide component is operably connected to the y-axis ball screw. A second stepper motor is operably connected to the y-axis ball screw and is operative to actuate the y-axis ball screw, whereby actuation of the y-axis ball screw actuates the second guide component in the y-direction. 
     The invention, in another form thereof, comprises a method of guiding a marking laser. The method of this form of the current invention includes the steps of: providing a laser source, providing an x-y axis guiding mechanism, and operatively positioning the laser source whereby a laser beam produced by the laser source will be guided by the x-y axis guiding mechanism. 
     In one form of the current invention, the step of providing an x-y axis guiding mechanism further includes the steps of: providing a first reflective surface, positioning the first reflective surface whereby a laser beam from the laser source will travel substantially along the z-axis and contact the first reflective surface and the laser beam will travel substantially along the x-axis after contacting the first reflective surface, providing a second reflective surface, positioning the second reflective surface so that the laser beam will contact the second reflective surface and the laser beam will travel substantially along the y-axis after contacting the second reflective surface, providing a third reflective surface, positioning the third reflective surface so that the laser beam will contact the third reflective surface and the laser beam will travel substantially along the z-axis after contacting the third reflective surface. In one form of the current invention, the method of guiding a marking laser further includes the steps of: moving the second reflective surface and the third reflective surface in unison along the x-axis and moving the third reflective surface along the y-axis. 
     An advantage of the present invention is the ability to provide a low cost precision guiding apparatus for a laser marking device. The new invention reduces the requirement for high cost, high tolerance parts. 
     Another advantage of the present invention is the ability to provide precision guiding with an x-y axis guiding system without having to continually replace bearings. 
     A further advantage of the present invention is the ability to achieve the required precision for a laser marking device while utilizing an x-y axis guiding apparatus. 
     Yet another advantage of the present invention is the ability to provide a self-wear compensating bearing which when utilized with an x-y axis guiding system, supplies the required precision for laser guiding. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a partial cut-away perspective view of a laser marking device of the current invention; 
     FIG. 2 is a partial cut-away side elevational view of a laser marking device of the current invention; 
     FIG. 3 is a partial sectional end elevational view of a laser marking device of the current invention; 
     FIG. 4 is a sectional view of a portion of the x-y axis guiding apparatus in accordance with the current invention; and 
     FIG. 5 is a side elevational view of a wear compensating bearing of the current invention. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and particularly to FIG. 1, laser marking device  50  includes laser source  20  and x-y axis guiding apparatus  32 . Control circuitry  42  is operatively connected to a computational device (not shown) and controls x-y axis guiding apparatus  32 . 
     Laser source  20  produces a laser beam which exits laser source  20  and contacts first reflective surface  12 . The laser beam produced by laser source  20  travels in the z-direction as it exits laser source  20 . The beam then travels in the x-direction as it is redirected by first reflective surface  12 . After contacting first reflective surface  12 , the laser beam contacts second reflective surface  14  and is redirected in the y-direction. Third reflective surface  44  (FIG. 2) is operatively positioned to redirect the laser beam after the beam exits second reflective surface  14 . The laser beam travels in the z-direction after contacting third reflective surface  44 . After contacting third reflective surface  44 , the laser beam exits through aperture  46  (FIG. 1) of protection plate  36 . 
     Second reflective surface  14  and third reflective surface  44  are operatively connected to first guide component  10  such that movement of first guide component  10  along the x-axis simultaneously moves both second reflective surface  14  and third reflective surface  44  in the x-direction. 
     As illustrated in FIG. 3, first guide component  10  is operatively connected to x-axis guide shafts  22 . First guide component  10  is further operatively connected to x-axis ball screw  26 . X-axis ball screw  26  is connected to first stepper motor  16 , which is connected to control circuitry  42 . First stepper motor  16  is operative to actuate x-axis ball screw  26 , which produces movement of first guide component  10  in the x-direction. 
     Second guide component  18  is operatively connected to y-axis guide shafts  24  and to y-axis ball screw  28 . Y-axis ball screw  28  is operatively connected to second stepper motor  30 , which is communicatively connected to control circuitry  42 . Second stepper motor  30  is operative to actuate y-axis ball screw  28 , which produces motion of second guide component  18  in the y-direction. 
     Bearings  48  are provided between first guide component  10  and x-axis guide shafts  22  as well as between second guide component  18  and y-axis guide shafts  24 . FIG. 4 illustrates bearings  48  in operative relationship with y-axis guide shaft  24  and second guide component  18 . A similar configuration is utilized with x-axis guide shafts  24  and first guide component  10 . As illustrated, bearings  48  include groove  52  into which annular spring  54  is placed. As illustrated in FIG. 5, bearings  48  include at least one elongate aperture or slot  56 . 
     In operation, control circuitry  42  is operatively connected to a computational device (not shown) which is utilized to control the marking activity of laser marking device  50 . First guide component  10  is utilized to move both second reflective surface  14  and third reflective surface  44  in the x-direction to control the markings created by laser marking device  50  in the x-direction. Similarly, second guide component  18  is utilized to reposition third reflective surface  44  in the y-direction to control the markings created by laser marking device  50  in the y-direction. In this way, the combined movement of first guide component  10  and second guide component  18  produces the desired movement of the laser beam created by laser marking device  50  and thus, creates the desired mark. First stepper motor  16  is utilized to move first guide component  10  along the x-axis, while second stepper motor  30  is utilized to move second guide component  18  along the y-axis. Annular spring  54  is placed in tension and keeps bearings  48  in operative relationship with the guide shaft along which they are mounted. Tension adjusting means may be utilized to provide the desired tension when annular spring  54  is applied and during operation. As bearings  48  wear, annular springs  54  maintain bearings  48  in operative contact with the relevant guide shafts as allowed by apertures  56  (as bearings  48  wear, the sides of apertures  56  are brought closer together as the tension in O-rings  54  maintain bearings  48  in central operative contact with the relevant guide shafts). In this way, the gaps between the bearings and the guide components which occur as bearings  48  wear is taken up and the required precision of laser marking device  50  is maintained. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.