The present invention relates to generally to a method of making a surface treating article and such surface treating article, and more particularly to a method of sensing the location of a fastener on a surface treating web and thereafter cutting the surface treating web around the fastener to provide a surface treating article, and such a surface treating article.
Machine vision and methods of employing machine vision are known in the art. For example, U.S. Pat. No. 6,005,978 (Garakani) describes an apparatus and method for a two-dimensional search for a model image using edge-based and area-based matching. U.S. Pat. No. 5,978,521 (Wallack and Michael) describes improved methods for determining a calibration relationship among the imaging reference frames of multiple cameras that acquire images of a common moveable object. U.S. Pat. No. 6,064,759 (Buckley et al.) teaches an automatic inspection method and apparatus using machine vision cameras to inspect a three-dimensional object.
Adaptive operations enabled by machine vision systems are also known in the art. For example, U.S. Pat. No. 5,777,880 provides a method and apparatus for correctively guiding an item on a desired path along a material. U.S. Pat. No. 5,380,978 (Pryor) describes the use of datums on three-dimensional objects for the purpose of optically guided positioning. U.S. Pat. No. 5,886,319 (Preston et al.) discloses a method and apparatus for guiding a laser cutter along a path on a patterned material using machine vision.
Various articles and methods for attaching fasteners to articles are known in the art. For example, U.S. Pat. No. 4,551,189 to Peterson discloses a friction welding fastener system for fusing a thermoplastic material fastener to a substrate by heat of friction induced through the application of rotative and axial forces applied to the fastener. A cavity is formed inwardly of the bottom surface of the thermoplastic base member and a heat activated adhesive material having a bonding affinity for both the base material and the substrate material is inserted into the cavity to form a layer having a thickness equal or greater than the thickness of the base member. The base member is rotated with sufficient rotative and axial forces to cause the heat activated adhesive layer to adhere to the substrate.
European Patent Application 937 544 A2 to Smith discloses a method of producing an abrasive treatment disc, whereby the disc is formed from an abrasive material ultrasonically welded to a mounting member.
U.S. Pat. No. 5,931,729 to Penttila et al. discloses a method of spin welding a fastener to an article and such an article. The fastener is melt-bonded to the back of the surface conditioning disc. The surface treating article comprises a working surface adapted to treat a workpiece surface, and a back surface, the back surface comprising an open woven scrim. In a preferred embodiment, the surface treating article has a nonwoven abrasive surface conditioning disc. The Penttila et al. reference states it is also possible for the surface treating article to be a coated abrasive disc, a polishing pad, a brush, or a similar surface treating element.
Applicant's copending U.S. patent application Ser. No. 09/551477, filed on Apr. 18, 2000, teaches a method of attaching a fastener to an abrasive article via spin welding and employing an intermediate thermoplastic adhesive layer.
U.S. Pat. No. 3,561,928 to Block et al. discloses an abrasive disk and a method of making an abrasive disk, which includes impregnating a compressible porous backing sheet matrix having a plurality of segments defining voids with a bonding material, which coats the segments to form a backing sheet. The backing sheet is then placed next to a hub and the two are heated and squeezed to compress the backing sheet and cause the bonding material to flow to bond the hub to the backing sheet. The large lamination may then be cut to form a number of the abrasive disks.
Surface conditioning discs having a threaded button bonded to the back side of the disc by an adhesive are available commercially as Roloc™ surface conditioning discs from Minnesota Mining and Manufacturing Company, St. Paul, Minn. These surface conditioning discs have an abrasive member and a fastener attached to the abrasive member by a layer of thermosetting adhesive. The fastener has a base and a threaded portion for attaching to a suitable back-up pad. These surface conditioning discs are assembled by first loading the fastener into heated fixture (typically 200–260° C.), such that the threaded portion of the fastener is held by the heated fixture and the base is exposed. The heated fixture heats the fastener. Next, a layer of thermosetting adhesive is applied to the fastener base, typically by spraying. After spraying the thermosetting adhesive, a circular or disc-shaped abrasive member is centered relative to the fastener held by the heated fixture and then makes contact with the layer of thermosetting adhesive on the fastener. The abrasive member and fastener are held in a compressive force until the layer of thermosetting adhesive has cured. Then, the surface conditioning disc is removed from the heated fixture.
Threaded fasteners for surface treating articles are taught in U.S. Pat. No. 3,562,968, “Surface Treating Tool,” Johnson et al.
It has been known to cut coated abrasive webs with lasers to form coated abrasive discs.
One aspect of the present invention provides a method of making a surface treating article. The method comprises the steps of: a) providing a surface treating web with a fastener attached thereto; b) sensing the position of the fastener on the surface treating web; and c) cutting the surface treating web around the fastener to provide a surface treating article including the fastener.
In one preferred embodiment of the above method, step b) further comprises sensing the position of the center of the fastener and step c) comprises cutting the surface treating web around the center of the fastener to provide a surface treating article including the fastener centered thereon. In another aspect of this embodiment, step c) further comprises cutting the surface treating web around the fastener in the shape of a disc. In another preferred embodiment of the above method, step b) is performed using machine vision. In another aspect of this embodiment, the fastener includes a fiducial, and step b) further comprises using the machine vision to determine the position of the fiducial to thereby determine the position of the fastener on the surface treating web.
In another preferred embodiment of the above method, step c) further comprises laser cutting the surface treating web around the fastener to provide a surface treating article with the fastener thereon. In another preferred embodiment of the above method, the method further comprises: d) advancing the web forward to bring a second fastener attached to the surface treating web to within a desired region; and e) repeating steps b) and c) with regard to the second fastener to provide a second surface treating article. In another aspect of this embodiment, the method is a continuous method in which a plurality of fasteners are sequentially brought into the desired region, and steps b) and c) are then repeated with respect to each of the plurality of the fasteners.
In yet another preferred embodiment of the above method, step c) further comprises partially cutting the surface treating web around the fastener to provide a partially-cut surface treating article with the fastener thereon, and subsequently separating the surface treating article from the surface conditioning web. In another preferred embodiment of the above method, the method further comprises the step of attaching the fastener to the surface treating web prior to step a). In another aspect of this embodiment, the step of attaching the fastener to the surface treating web comprises spin welding. In another aspect of this embodiment, the fastener comprises a thermoplastic material. In yet another aspect of this embodiment, the step of attaching the fastener to the surface treating web comprises placing a thermoplastic layer of adhesive between the fastener and the surface treating web prior to spin welding. In another preferred embodiment of the above method, the surface treating web comprises a coated abrasive web.
Another aspect of the present invention provides an alternative method of making a surface treating article. This alternative method comprises the steps of: a) providing a surface treating web with a fastener attached thereto; b) thereafter laser cutting the surface treating web around the fastener to provide a surface treating article, including the fastener.
In one preferred embodiment of the above method, the method further comprising the step of sensing the position of the fastener on the surface treating web prior to step b). In another aspect of this embodiment, the method further comprises the step of determining the position of the center of the fastener on the surface treating web prior to step b). In another preferred embodiment of the above method, the method further comprises the step of determining the position of the center of the fastener prior to step b) and step b) comprises laser cutting the surface treating web around the center of the fastener to provide a surface treating article with the fastener centered thereon. In another aspect of this embodiment, step b) further comprises laser cutting the surface treating web around the fastener in the shape of a disc.
In another preferred embodiment of the above method, the method further comprises the step of using machine vision in sensing the position of the fastener on the surface treating web prior to step b). In another aspect of this embodiment, the fastener comprises a fiducial to determine the position of the fastener on the surface treating web using machine vision. In another preferred embodiment of the above method, the method further comprises the steps of: c) advancing the web forward to bring a second fastener attached to the surface treating web to within a desired region; and d) repeating step b) with regard to the second fastener to provide a second surface treating article. In another aspect of this embodiment, the method is a continuous method in which a plurality of fasteners are sequentially brought into the desired region, and steps b) and c) are then repeated with respect to each of the plurality of the fasteners. In yet another preferred embodiment of the above method, step b) further comprises partially laser cutting the surface treating web around the fastener to provide a partially-cut surface treating article with the fastener thereon, and subsequently separating the surface treating article from the surface treating web.
In another preferred embodiment of the above method, the method further comprises the step of attaching the fastener to the surface treating web prior to step a). In another aspect of this embodiment, the step of attaching the fastener to the surface treating web comprises spin welding. In another aspect of this embodiment, the step of attaching the fastener to the surface conditioning web comprises placing a thermoplastic layer of adhesive between the fastener and the surface conditioning web prior to spin welding. In another preferred embodiment of the above method, the surface treating web comprises a coated abrasive web.
Another aspect of the present invention provides a method of making a plurality of surface treating articles. The method comprises the steps of: a) providing a surface treating web with a plurality of fasteners fastened thereto; b) sensing the position of at least one of the plurality of fasteners on the surface treating web; and c) cutting the surface treating web around each of the plurality of fasteners to provide a plurality of surface treating articles, each including one of the plurality of fasteners.
In one preferred embodiment of the above method, each of the plurality of fasteners is located in a predetermined position forming an array of fasteners. In another aspect of this embodiment, the plurality of fasteners includes a first fastener and a second fastener, where step b) includes sensing the position of the first fastener and where the position of the second fastener is determined from the relative positions of the first fastener and the second fastener. In another aspect of this embodiment, step b) further comprises sensing the position of the first fastener with machine vision. In yet another preferred embodiment of the above method, step b) further comprises determining the position of the center of at least one of the plurality of fasteners and step c) comprises cutting the surface treating web around the centers of the plurality of fasteners to provide a plurality of surface treating articles each including one of the plurality of fasteners centered thereon. In another preferred embodiment of the above method, at least one of the plurality of fasteners includes a fiducial to determine the position of the at least one fastener on the surface treating web.
In yet another preferred embodiment of the above method, step c) further comprises laser cutting the surface treating web around the plurality of fasteners to provide a plurality of surface treating articles each including one of the plurality of fasteners thereon. In another preferred embodiment of the above method, step c) further comprises partially cutting the surface treating web around the plurality of fasteners to provide a plurality of partially-cut surface treating articles each including one of the fasteners thereon and subsequently removing the plurality of surface treating articles from the surface treating web.
In another preferred embodiment of the above method, the method further comprises the step of attaching the plurality of fasteners to the surface treating web in a predetermined array prior to step a). In another aspect of this embodiment, the step of attaching the plurality of fasteners to the surface treating web in a predetermined array comprises spin welding. In yet another aspect of this embodiment, the step of attaching the fasteners to the surface treating web comprises placing a thermoplastic layer of adhesive between the fastener and the surface treating web prior to spin welding. In another preferred embodiment of the above method, the surface treating web comprises a coated abrasive web.
Another aspect of the present invention provides a surface treating article. The surface treating article comprises: a) a surface treating member; and b) a fastener on the surface treating member including a drive member, where the drive member includes a distal end, where the distal end includes a fiducial located thereon.
In another preferred embodiment of the above surface treating article, the fiducial includes a first reflective surface and a non-reflective surface. In another aspect of this embodiment, the non-reflective surface is at an angle relative to the first reflective surface. In another aspect of this embodiment, the distal end of the fastener includes a second reflective surface. In yet another aspect of this embodiment, the non-reflective surface is at an angle relative to the first reflective surface and the second reflective surface. In yet another aspect of this embodiment, the first reflective surface and the second reflective surface are parallel.
In another preferred embodiment of the above surface treating article, the surface treating member comprises an abrasive member, and where the abrasive member includes a working surface and a back surface opposite the working surface. In another aspect of this embodiment, the working surface comprises a coated abrasive. In another preferred embodiment of the above surface treating article, the working surface comprises a non-woven surface.
Another aspect of the present invention provides an apparatus for making a surface treating article. The apparatus for making a surface treating article comprises: a) attaching means for attaching a fastener to a surface treating web; and b) cutting means for laser cutting the surface treating web around the fastener to provide a surface treating article.
Another aspect of the present invention provides an alternative apparatus for making a surface treating article. The apparatus for making a surface treating article comprises: a) a spinwelder for attaching a fastener to a surface treating web; b) machine vision system to determine the position of the fastener on the surface treating web; and c) a laser to cut the surface treating web around the fastener to provide a surface treating article with a fastener thereon. In one preferred embodiment of the above apparatus, the apparatus further includes: d) a web carrier for advancing the surface treating web.
The present invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein:
A preferred embodiment of a surface treating article 10 of the present invention is illustrated in
The surface treating article 10 includes a surface treating member 40 and a fastener 12. The relative size of the surface treating member 40 to the fastener 12 may be different from what is illustrated in
The surface treating member 40 includes a working surface 42 and a back surface 44 opposite the working surface 42. The surface treating member 40 also includes a peripheral surface 46 extending between the working surface 42 and the back surface 44. As illustrated, the fastener 12 is attached to the back surface 44 of the surface treating member 40. Alternatively, the fastener 12 may be attached to the working surface 42 of the surface treating member 40.
The surface treating member 40 is illustrated in the shape of a circle. However, surface treating member 40 may be any shape. Preferably, the surface treating article 40 is a disc, which means it is capable of rotating about a drive member.
In the illustrated embodiment, the surface treating member 40 is a coated abrasive member 40. The back surface 44 includes a backing. A preferred backing is one that is thick enough, stiff enough and rugged enough to withstand the spin welding process. For example, suitable backings include a resin-impregnated cloth, a polymer-laminated cloth, or a polymer-impregnated paper. Coated abrasive members and their method of manufacture are well known to those skilled in the art. One example of a coated abrasive member 40 is illustrated in U.S. Pat. No. 5,766,277, “Coated Abrasive Article and Method of Making the Same,” DeVoe et al., the entire disclosure of which is incorporated herein by reference. Alternatively, the surface treating member 40 could be a non-woven abrasive member 40. A non-woven abrasive member 40 includes fibers needle tacked into a woven scrim. A preferred non-woven abrasive member is described in detail in U.S. Pat. No. 3,688,453, “Abrasive Articles,” Legacy et al., the entire disclosure of which is incorporated herein by reference.
Fastener 12 includes a generally planar base 15 and a drive member 17. The planar base 15 includes a generally planar surface 14 and a second surface 16 opposite the planar surface 14. In one preferred embodiment, the planar surface 14 of the fastener 12 has a diameter of approximately 3 cm (1.2 in), although larger and smaller fasteners are within the scope of the invention. As illustrated in
Preferably, a fiducial 18 is located on the fastener 12. More preferably, a fiducial 18 is located on the distal end of drive member 17 on distal end surface 19. “Fiducial” is used herein, including the claims, to describe any line, mark or shape that is used as a standard of reference for sensing a location. For example, fiducial 18 is used to sense the location of fastener 12 on a surface treating web, which is described in greater detail below.
Preferably, fiducial 18 includes first reflective surface 20 and a non-reflective surface 24. More preferable, the first reflective surface 20 and the non-reflective surface 24 are concentric. Most preferably, the first reflective surface 20 is in the shape of a circle and the non-reflective surface 24 is in the shape of an annulus surrounding the first reflective surface 20. The non-reflective surface is preferably at an angle α measured relative to the first reflective surface 22. Preferably, α is between 20° and 70−°. More preferably, α is between 30° and 60°. Most preferably, α is 45°. The distal end surface 19 of the drive member 17 includes a second reflective surface 22. Preferably, the first reflective surface 20 and the second reflective surface 22 are parallel to one another. As illustrated in
Preferably, fastener 12 is made of a thermoplastic material. Examples of suitable thermoplastic materials include nylon and polyamides. Alternatively, fastener 12, may be made of a metal. A suitable metal is steel.
Preferably, the fastener 12 is spin welded directly onto the surface treating member 40. Methods of spin welding are known in the art. Generally, spin welding includes placing the fastener 12 and surface treating member 40 in contact with one another and then rotating the fastener 12 and surface treating member 40 relative to one another so as to soften the material of the fastener 12 to form a melt bond between the fastener 12 and surface treating member 40. For example, one method of spin welding a fastener to a surface treating article is disclosed in U.S. Pat. No. 5,931,729 to Penttila et al., the entire disclosure of which is incorporated herein. The preferred spin welding method for the fastener 12 and surface treating member 40 is described below.
Another suitable method of attaching the fastener 12 to the surface treating member 40 is disclosed in U.S. patent application Ser. No. 09/551477 (Fritz et al.), filed on Apr. 18, 2000, the entire disclosure of which is incorporated herein. This patent application generally discloses a method of attaching a fastener to a surface treating member by first placing a layer of adhesive between the fastener and surface treating member. Then, the fastener and surface treating member are spin welded together with the layer of adhesive between them, so as to soften the layer of adhesive. Upon cooling, the layer of adhesive forms a bond between the fastener and the surface treating member 40. Preferably, the adhesive is a thermoplastic adhesive.
Another suitable method of attaching the fastener 12 to the surface treating member is by using a layer of thermosetting adhesive between the fastener 12 and the surface treating member 40, which is cured by heat. However, the method of attaching the fastener 12 to the surface treating member 40 is not critical and the fastener 12 may be attached to the surface treating member 40 in any way known to those skilled in the art.
As illustrated in
After the fasteners 12 are spin welded, the web advances forward to the machine vision and cutting station 80 of the apparatus 50. The web 30 comes to a stop to remain stationary under the machine vision and cutting station 80. The machine vision system 82 senses the position of the fasteners 12 on the web 30 that were spin welded onto the web at the previous station. Next, the laser 84 partially cuts the web 30 around each of the fasteners 12 to form partially cut surface treating articles 10. The web 30 then starts again and proceeds from the machine vision and cutting station 80 to the separation station 90 of apparatus 50. The hollow cylinders 94 of the upper ram assembly 91 mechanically separate the partially cut surface treating articles 10 from the web 30. The separated surface treating articles 10 fall into the receiving bin 86. The web progresses from the separation station 90 to the nip assembly formed between the upper and lower web rolls 68, 69. Finally, the remaining web then progresses from the nip assembly formed between the upper and lower web rolls 68, 69 to the wind assembly 88, where the remaining web 30 is wound around the surface treating web roll 89. Preferably, roll 89 includes a motor for winding the web around the roll.
Preferably, the surface treating web 30 is an abrasive web. More preferably, abrasive web may be either a coated abrasive web or a non woven abrasive web. Preferably, the web 30 is between 2 and 60 inches wide. More preferably, the web 30 is between 15 and 36 inches wide. However, the web width could vary depending on the number and size of fasteners 12 attached to the web 30 and the size of the finished surface treating article 10.
Preferably, portions of the web 30 move intermittently between the individual stations at approximately the same speed. Preferably, the average speed of the web 30 is between 5 and 150 inches/minute through apparatus 50, and more preferably between 25 and 75 inches/minute through apparatus 50. The average speed is calculated taking into account the web acceleration from a stationary position at one station and web deceleration to a stationary position at an adjacent station.
As seen in
In the spin weld station 70, spin welder stand 72 holds a plurality of spin welders 74 directly above the moving web 30. In the machine vision and cutting station 80, the stand 83 holds the machine vision system 82 and laser cutting system 84 directly above the moving web 30. In the separation station 90, stand 110 holds the separation apparatus 99. The separation apparatus 99 includes an upper ram assembly 91 and a web back up assembly 92. The upper ram assembly 91 is positioned above the moving web 30. The web back up assembly 92 is located below the moving web 30 opposite the upper ram assembly 91.
In the fastener loading station 60, the fasteners 12 are loaded onto platen 62 in predetermined locations. A vacuum (not shown) holds the fasteners 12 in their respective locations. Preferably, the fasteners are arranged relative to each other to coordinate with the location of the chucks 76 in the spin welders 74 located in stand 72. Preferably, the fasteners are arranged in a first array 120 and a second array 122 (as shown in
As illustrated, stand 72 may hold up to a total of thirteen spin welders 74. More or less spin welders 74 may be used depending on the size of the finished surface treating articles 10 and the width of the web 30. The first row of spin welders 74, closest to the fastener loading station 60, may contain up to six spin welders. However, for clarity in the drawing, only two spin welders 74 are illustrated. The second row of spin welders 74, located opposite the first row, may contain up to seven spin welders 74. However, for clarity, only two of the seven spin welders 74 are shown. The second row of spin welders may be seen more clearly in
Chuck 76 can be any suitable fixture that will hold the fastener 12 during the spin weld operation. Chuck 76 must grip the fastener 12 securely enough to avoid slippage of the fastener 12 within the chuck 76 when the fastener is spun against the surface treating web 30. Chuck 76 should also provide for easy release of the fastener 12 after the spin weld process. Chuck 76 thus may include moveable elements for gripping and releasing the fastener 12, as is well known in the art.
The forward travel of the web 30 stops below the spin welders 74 by upper and lower belts 58, 59. Plate 75 located below the web 30 (illustrated in
A preferred method of spin welding the fastener 12 to the surface treating web 30 is as follows. In general, the spin weld method comprises the steps of holding stationary the surface treating web 30, mounting the fastener 12 in a chuck 76 to be driven by the spin welder 74, accelerating the chuck 76 and fastener 12 to the desired rotational speed, activating the drive mechanism 152 to move the planar surface 14 of the fastener 12 into contact with the surface treating web 30, applying sufficient force between the fastener 12 and surface treating web 30 while the fastener is spinning to achieve a frictional temperature required to soften the planar surface 14, allowing the chuck 76 and fastener 12 to stop rotation, maintaining force between the fastener 12 and surface treating web 30 while the planar surface 14 of the fastener 12 sufficiently cools to form a bond between the fastener 12 and surface treating article web 30, and releasing the fastener 12 from the chuck 76. The surface treating web 30 is mechanically held stationary between the upper and lower belts 58, 59 (not shown) to keep the web 30 stationary during the spin welding process. Optionally, adhesive may be placed between the planar surface 14 of the fastener 12 and the surface treating web 30 prior to spin welding them together so as to form an adhesive bond between the fastener 12 and surface treating web 30.
The following parameters are preferred when spin welding a nylon fastener 12 on a coated abrasive web with a backing comprising a resin-impregnated cloth or polymer-backed cloth. The parameters found to affect the strength of the melt-bond between the fastener 12 and surface treating web 30 are as follows. The force that the chuck 76 applies to the system is preferably between about 250 and 1100 lb., more preferably between about 300 and 700 lb., and most preferably between about 350 and 500 lb. The speed of the motor 150 is preferably between about 500 and 8000 RPM, more preferably, between 2000 and 6000 RPM, and most preferably, between about 2500 and 4500 RPM. The spin time is preferably between about 0.05 seconds and 0.6 seconds. More preferably, the spin time is preferably between about 0.2 seconds and 0.45 seconds. The spin time is a measurement of how long the rotary motor 150 is maintained under power from the time the chuck 76 is positioned vertically within approximately 0.125 inches or less from the web 30 (essentially at the time of contact between the fastener 12 and the web 30) and ends with the command to remove power from the motor 150 after the fastener 12 contacts the surface treating web 30. After the power is removed from the rotary motor 150, the force between the fastener 12 on the web 30 must be maintained for a period of dwell time to form a sufficient bond between the fastener 12 and the web 30. Preferably, the dwell time is between 0.1 and 1 seconds, and more preferably, between 0.2 and 0.5 seconds.
Because the spin welders 74 are mounted in fixed positions in the stand 72, the fasteners 12 are spin welded in predetermined positions on the web. This is convenient for sensing the positions of the fasteners 12 and cutting around the fasteners 12 on the web 30 to make surface treating articles 10.
When the web enters the machine vision and cutting station 80, illustrated in
Preferably, the first reflective surface 20 is in the shape of a circle and reflects back a white circle. Preferably, the non-reflective surface 24 is in the shape of an annulus surrounding the first reflective surface 20 and causes a black annulus centered around the white circle. Preferably the second reflective surface 22 is in the shape of an annulus surrounding the non-reflective surface 24 and reflects back a white annulus centered around the black annulus. The combination of these three features in the image creates a pattern of a “bull's eye” which the machine vision system scans for on the web 30. Using this image, the computer can then determine the location of the fastener 12 on the web. Once the position of the fastener 12 is determined, the position of the fastener is sent to the laser control system. Then, the laser is directed to cut around the fastener to form a surface treating article 10. Preferably, machine vision system computer may determine the position of the center of the fastener using the same image. Once the position of the position of the center of the fastener 12 is determined, the output is sent to the laser control system. Then, the laser is directed to cut around the center of the fastener to form a surface treating article with the fastener 12 centered thereon.
Any commercially available machine vision system 82 capable of obtaining the conditions described herein may be used, such as the Acuity™ VP-2000 available from RVSI Acuity, Inc. located in Nashua, N.H. Another suitable machine vision system 82 includes DVT Series 600 available from DVT, Inc. located in Norcross, Ga.
The laser 84 cuts around the fasteners 12 located on the web 30 to form surface treating articles 10. The laser 84 is illustrated as starting to cut around the first fastener 124 of the first array of fasteners 120. The laser will then continue to cut around the second fastener 126 and proceed to the third, fourth and fifth fasteners 128–132 in the first array 120 before proceeding to cut around the fasteners 124–132 in the second array 122.
Each fastener 12 may be sensed individually as mentioned above prior to cutting around each fastener 12. However, it is also possible to sense only one or some of the fasteners 12 within an array of fasteners and then to determine location of all of the fasteners 12 in the array prior to cutting around each fastener within the array. For instance, if an array of fasteners included only a first fastener and a second fastener and it is known that the first fastener and second fastener are located a certain distance and direction from one another on the web 30, then once the position of the first fastener has been sensed, the position of the second fastener may be determined from the relative positions of the first fastener and the second fastener.
Referring to
Preferably, the fiducial 18 is centered relative to the drive member 17. The benefit of having the fiducial 18 centered relative to the drive member 17 is that the laser 84 may cut a nearly perfectly centered surface treating article with the fastener 12 centered thereon. This allows for final surface treating article which will wear more evenly over time in comparison to a surface treating article having a fastener that is not centered.
Preferably, the laser partially cuts the web 30 around the fasteners 12 to form a partially cut surface treating article 10. Preferably, the laser 84 cuts partially through the thickness of the web 30 so that the surface treating article 10 stays with the web until it is received at the separation station 90. If the surface treating web is a coated abrasive web, the laser preferably cuts through the backing on the back surface, but not the abrasive coating on the working surface of the web. Alternatively, the laser 84 may cut all the way through the web 30 to separate the surface treating articles 10 from the web completely, and thus, eliminating the need for the separation station 90.
A suitable laser system includes a laser generator coupled to required services, a beam delivery system, and a work surface containing or attached to an exhaust system. Preferably, the beam delivery system of laser 84 includes the following parameters: a galvanometer-based or other scanning optical-based system, minimum of 50 mm aperture, a focused beam size of less than 300×10−6 m in diameter, minimum field size of 15 inches, power capability of 2500 watts, speed of mirrors to direct the beam at a speed of between 300 and 2000 mm/sec (measured on the working surface) and acceleration greater than 200 g (measured on the working surface). Preferably, the beam delivery system is a completely reflective optical system, as opposed to a transmissive optical system. Preferably, the suitable laser system includes a total system accuracy of better than plus or minus 0.004 inches in any field position and for the lifetime of the equipment.
Any commercially available lasers 84 capable of obtaining the conditions described herein may be used, such as the LPM-2500 and LPM-1000 available from LasX Industries, Inc. located in White Bear Lake, Minn.
After the surface treating articles 12 are partially cut, the web advances to the separation station 90 of the apparatus 50 illustrated in
Web back-up assembly 92 is located below the upper ram assembly 91 and below the moving web 30. Web back-up assembly 92 includes plate 100 having a plurality of holes 101 sized to receive the cylinders 94 of the upper ram assembly 91. Web back-up assembly 92 includes a frame 105, which supports plate 100. Mounted inside frame 105 just below plate 100 are two back up plates 102. The two back up plates pivot about pivots 103. Two transfer chutes 104 are mounted below the two back up plates 102 inside frame 105. The transfer chutes 104 are fixed within the frame 105 and do not move. When the upper ram assembly 91 pushes down onto the web to mechanically separate the partially cut surface treating articles 10 from the web 30, the back up plates 102 are pivoted up to contact the cylinders 94 as they move through holes 101 in plate 100. After the partially cut surface treating articles 10 are mechanically separated from the web 30, they fall onto the plate 102. Next, the back up plates 102 pivot about pivots 103 into the down position, as illustrated in
After the surface treating articles 10 are removed from the web 30, the web 30 proceeds from the separation station 90 of the apparatus 30 to the wind assembly 88, which was illustrated in
Preferably, the stations 52, 60, 70, 80, 90, and 88 of apparatus 50 are coordinated such that the web 30 stops and each station does its step simultaneously at different portions of the web. However, stations 52, 60, 70, 80, 90, and 88 may be each independent or could be combined in a variety of sequences.
Although the cutting means illustrated for apparatus 50 is a laser, other cutting means may be used instead. For instance, suitable cutting means includes die cutting, water jet cutting, or ultrasonic cutting. As mentioned above, the fasteners 12 may be attached to the web 30 by methods other than spin welding.
Although it is preferable to use machine vision in combination with the laser to perform the inventive method, other combinations are within the invention, such as combining machine vision with the other suitable cutting means mentioned above or combining other sensing means with laser cutting.
The present invention has now been described with reference to several embodiments thereof. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. All patents and patent applications cited herein are hereby incorporated by reference. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the exact details and structures described herein, but rather by the structures described by the language of the claims, and the equivalents of those structures.
This application is a divisional of U.S. application Ser. No. 10/462,479, filed Jun. 17, 2003, now U.S. Pat. No. 6,817,935, which is a divisional of U.S. application Ser. No. 09/607,210 filed Jun. 30, 2000, now U.S. Pat. No. 6,609,951, issued Aug. 26, 2003.
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Number | Date | Country | |
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Number | Date | Country | |
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Parent | 10462479 | Jun 2003 | US |
Child | 10936419 | US | |
Parent | 09607210 | Jun 2000 | US |
Child | 10462479 | US |