US3734700A - Article abrading apparatus - Google Patents

Abstract

The disclosure is an article abrading apparatus having an article carrier belt and arms including abrading members moving across the belt with abrasive reciprocating motion. Abrasive contact with articles of flat and triangular cross sectional shapes is provided by a pivotally hinged arrangement of abrading members which are positioned by movable roller bars sensing the surface tilt of contour of an article passing beneath.

Description

1973 T. GUTBERREZ ET AL 3,734,700

ARTICLE ABRADING APPARATUS Filed May 10, 1971 3 Sheets-Sheet 1 INVENTORS THOMAS GUTI ERREZ WALLACE AMARAL.

PATENT AGENT May 22, 1973 T, GU-HERREZ ET AL 3,734,70Q

ARTICLE ABRADING APPARATUS Filed May 10, 1971 3 Sheets-Sheet 2 INVENTORZ THOMAS GUTIERREZ WALLACE AMARAL 4 /%//m 1;; f%// PATENT AGENT O 0% @o WN @N o mm wm E m Filed May 10, 1071 3 Sheets-Sheet m m $1 1' L0 \X Q on G3 N \9 m N O. a N g m l 1 N q r 6) no r -&

INVENTORS THOMAS GUTIERREZ WALLACE AMARAL BY 1 l ,V I

PATENT AGENT United States Patent Oflice 3,734,700 Patented May 22, 1973 3,734,700 ARTICLE ABRADIN G APPARATUS Thomas Gutierrez, 395 N. Madison St. 95050, and Wallace Amaral, 2547 Amethyst 95051, both of Santa Clara, Calif.

. Filed May 10, 1971, Ser. No. 141,761

Int. Cl. B24b 7/12 US. Cl. 5161 10 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION In printed circuit technology it is highly desirable to obtain circuit boards with smooth surfaces. Drilling holes through the boards for mounting components usually produces small surface burrs which interfere with subsequent circuit board plating operations. Hence, it is necessary in these cases to de-burr the circuit boards in at least one stage of circuit board preparation.

Some polishing, de-burring and similar surface treatment machines have previously used complex mechanisms to achieve the desired surface effect. This is especially true where orbital abrasive motion was applied to a surface. In order to treat the entire surface such machines must include means for moving the abrasive orbit only after suflicient treatment is applied to a certain location. One method of achieving this is by a complex camming arrangement.

On the other hand, simple machines such as rotating roller brushes usually require large abrasive surfaces, any part of which is in contact with the treated material only a small portion of the time. Roller brushes have the disadvantage of producing a somewhat uneven result, especially if some single part of the brush loses its abrasive quality.

The object of the present invention is to provide a simple, low cost, highly efficient abrading apparatus for generally fiat articles.

Another object is to provide an abrading apparatus for articles having a triangular cross section.

A further object is to provide an apparatus for abrading articles of both very small and large size.

Still a further object is to provide an article abrading apparatus whose abrading surfaces can be quickly and cheaply replaced.

SUMMARY OF THE INVENTION The above objects are achieved with an apparatus havmg liftable, tiltable abrasion arms mounted for transverse motion facing an article carrier belt or web. The arms include generally fiat sliding members extending over and across the article belt with an abrading member facing the belt and drive members from which the sliding members are suspended from a single pivot.

The drive members of the several arms are arranged in two sets, each rotatably cantilevered from an end and connected to a motive means on either one of the opposite sides of the belt. The pivot for each sliding member is slightly ofr center so that each sliding member will tilt with a see-saw motion when it is pulled across the surface of an article on the belt having a triangular cross section,

apex facing the sliding member. Since each drive member is rotatably cantilevered from one Side of the belt, each arm can be lifted.

The means which lifts the arms is a roller bar associated with each arm. Each roller is free to move up and down directly in front of each arm as it rides over articles which pass beneath it. Each arm has a pair of protruding lugs with a lug spaced on each side of the pivot and which contact the top of the roller. Thus when the roller is forced upward by an article passing beneath, the associated arm is elevated by the lugs riding on top of the roller. The pressure exerted by the lugs on the roller will cause the roller to tilt with a see-saw motion when the sliding member of each arm is pulled across the surface of an article having a triangular cross section. If the article surface is flat, both the roller and the sliding member will follow the flat contour of the 'article surface.

As the article advances on the belt beneath, the multiple abrasion arms will apply an abrading treatment to the article with the quality of abrasion determined by the grit or type of sandpaper, emery, polishing material, etc. selected for the abrading member. The types selected can be mixed for several stages of article surface treatment.

DESCRIPTION OF THE FIGURES FIG. 1 is a perspective partially cut-away view of the apparatus of the invention.

FIG. 2 is a side cut away view of the apparatus illustrated in FIG. 1.

FIG. 3 is an end sectional view taken along the line 3-3 in the direction of the arrows in FIG. 2.

FIG. 4 is a partial perspective of the article carrier belt of the apparatus of FIG. 1.

FIG. 5 is a first operational side view of a lifting and tilting means associated with the abrasion arms of the apparatus of FIG. 1.

FIG. 6 is a second operational side view continuing the motion shown in FIG. 5.

FIG. 7 is a third operational side view continuing the motion shown in FIG. 6.

FIG. 8 is a fourth operational side view continuing the motion shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the invention is described with reference to abrading machines for de-burring generally fiat and triangular cross sectional articles such as circuit boards, the apparatus described herein is equally useful for polishing, stripping and surface treating the same articles.

FIG. 1 is a perspective of the upper portion of the article abrading apparatus 11 of the present invention mounted in an enclosing frame 13. An article carrier belt 12 moves in a direction indicated by the arrow over a fiat bed plate 14 which serves as a horizontal belt guide. An article 16, such as a circuit board, is shown on belt 12 passing under feed roller 18. Stacking plate 15 is set to clear the belt slightly so that fiat articles may be stacked in front of it and pass underneath one at a time only. A stacking plate 15 keeps articles stacked without falling, yet allows single articles to pass thereunder. Stacking plate 15 can be cantilevered or otherwise secured in position. The contacts 20 of feed roller 18 are made of an elastomeric substance which is in contact with belt 12. Flat articles may be stacked in front of the feed roller 18 and stacking plate 15, but only one will pass underneath at a time due to the clearance set beneath plate 15. The feed rollers should yield to accommodate articles having triangular cross sections.

The leading edge of article 16 can be seen passing beneath a first liftable, tiltable abrasion arm 22. If an article has a triangular cross section, the article is placed on belt 12 so that the triangular section has a base colinear with roller 18 and an apex facing upward.

Each arm 22, 24, etc. includes a lifting means 26 operable in response to the approach of the article 16 toward the arm 22 as'explained below as well as in connection with the description of FIGS. 5, 6, 7 and 8.

The lifting means 26 associated with the arms 22, 24, etc. includes. a tiltable, liftable roller bar 28 placed on belt 12 under a pair of lugs 30, 31. The roller bar 28 is free to roll and be lifted and tilted by an article 16 passmg beneath it. The lateral and forward motion of the roller bar 28 is checked by slider blocks 32, 34. The degree of lift provided to the arms 22, 24, etc. by the lifting means 26 is proportional to the amount that the roller bar 28 is lifted as an article passes benath it. By lifting the lugs 30, 3 1 connected to each arm the lifting means 26 orients each associated arm to the surface elevation of an article passing beneath.

The number of arms 22, 24, etc. is selected to provide the amount of desired abrasion for the quality and type of surface being treated. For generally flat articles, six arms have been found to provide ample abrasion but this number is not critical.

Each of the liftable, tiltable arms 22, 24, etc., includes a drve member 36, 38, etc. rotatably cantilevered from one end which provides reciprocative motive means. Each drive member is pivotally connected at a pivot 39, 41, etc. to sliding member 40, 42, etc., respectively. Each pivot 39, 41, etc. is alternately off-center one way, then the other, allowing arms 22, 24, etc. to tilt clockwise and counterclockwise in a see-saw motion about a pivot as the sliding member is pulled across the surface of an article having a triangular cross section.

Each drive member, e.g. 36, is connected at an end 44 to a rocker bar 46 and held down at the opposite end by a spring 45 which controls tension of each sliding member on the article passing beneath it. The tension determines the amount of abrasion exerted on an article passing beneath it. The tension on all springs is generally set to be equal.

The sliding members, e.g. 40, also include a face portion 48 carrying an abrasion member extending across the belt in a slight interference relation to any article on said article carrier belt as explained below with reference to the description of FIG. through 8 below. The lugs 30, 31 are spaced on opposite sides of the central pivot 39 for lifting the sliding member 40 to which the pivot and lugs are attached. The slider blocks 32, 34 in which the sliding member 40 rests are made of a low friction material such as nylon or Teflon.

In operation the rocker arm 46 rocks back and forth about the shaft 50 pushing and pulling drive member end 44 and the connected sliding member 40. If an article 16 is under roller bar 28 the height of sliding member 40 of the abrasion arm 22 is adjusted by the roller to the proper elevation for surface de-burring or polishing or finishing, etc. If the article under a roller bar has a triangular cross section the sliding member will tilt about the pivot with a see-saw motion when it is pulled across the article surface. The spring tension on each' arm causes the arm to follow the surface contour and tilt when necessary.

The degree of "abrasion provided depends partially on the number of abrasion arms 22. A multiplicity of arms,

here six, is arranged in'first and second opposed sets with generally equal numbers of arms in each set having drive members cantilevered from either of the opposite sides of the belt. The first set including drive members 51, 53 is connected to drive member end 44 and first rocker bar 46 through the first driver rod 52, while the second set including drive members 54, 56 is connected to another drive member end through the second driver rod 58 and second rocker bar 59 for mutually opposed motion.

Abrading members, e.g. 82 on sliding member 48, maina liquid lubricant through sources in a sprinkler pipe 60 mounted Within a fluid shieldj FIG. 2 illustrates the sources 64 in sprinkler pipe 60 in the fluid shield 61 over the first set of drive members 36, 51, 53 and the second set of drive members 38, 54, 56. The fluid passes onto belt 12 and lubricates articles thereon before falling into the fluid sink 62,which is a large open tray extending beyond the edges. of belt 12 in a horizontal plane. 5 u The motivemeans forthe article abrading apparatus 11 are first and second motors 64, 66. Motor 64 transmits power to wheel 68 through the belt '67; On the oppbsite sides of the rim of wheel 68 is monted an eccentric power shaft 70 for providing reciprocative power to thefirst and second rocker bars 46, '59 through the drive shafts 71, 72. This provides opposed motion for drive members 36, 51, 53 of the first set of abrasion arms against the drive members 38, '54, 56 of the secondset of abrasion arms.

Power transmission is more clearly illustrated in FIG. 3 which shows wheel 68 driven by belt 67 and the drive shafts 71, 72 respectively mounted to the Wheel from the eccentric shaft 70. In operation, rotation of wheel 68 moves the rocker bars 46, 59 in opposite directions thereby causing opposed motion of the drive members 36, 38.

FIG. 3 also illustrates a means for recirculating lubricating fluid from sink 62 to sprinkler pipe 60 and the sources therein. A drain pipe 77 feeds a pump 78 which forces lubricating fluid upwards to the distal extremity of sprinkler pipe 60. As mentioned previously lubricating fluid falls downward from the sources in pipe 60 toward article carrier belt 12. Since fluid is recirculated metallic residual particles are kept out of sewer systemsthereby avoiding pollution by the debris from surface treating operations. I

FIG. 4 illustrates the detail of belt 12. Cleats 80 are regularly spaced on the surface of belt -12 for frictionally engaging articles placed thereon. To do this thecleats are usually made of rubber or a high friction elastomer. The cleats are usually more than one quarter inch high to allow fluid flow of lubricating fluid between cleats after the fluid has splashed onto the upper side of articles on belt 12. The spacing between cleats is about a quarter inch or so to permit very small circuit boards or-similar articles to be placed on the carrier belt without slipping. FIGS. 5 through 8 partially illustrate the abrading action of the present apparatus. Belt 12 moves in the direction of the arrow over the flat bed plate 14 carrying a generally rflat article 16 to be de-bUrredbThe article may have a horizontal upper surface or an upper surface tilted with respect to the horizontal. Bed plate 14 should be kept as flat as possible for even abrading operations.

In FIG. 5 the article 16 is seen to be approaching the feed roller 18. If other articles were stacked on article 16 the feed roller 18 functons to allow only one article at a time to pass underneath it. The sliding members 40, 42 are reciprocating in opposite directions in a plane in and out of the paper on which the figures are drawn at a height slightly above, i.e. about a millimeter, the-belt 12. The first and second roller bars 28, 29-are rotating as the belt moves but are kept from moving laterallyand forward by slider blocks not shown.

The sliding members 40, 42 each have abrading members 82, 84 respectively lining the side of the sliding members facing the belt and the forwardportion of sliding members in a shape resembling a ski. Slightly resilient pads 86, 88 are interposedbetween abrading members 82, 84 and sliding members 40, 42 respectively. 'Ihe abrading members may be made of any substance which will carry out the desired operation,.i.e. sanding, polishing, de-burring, surface finishing, ,etc. For d e-b urring purposes the abrading. member-is a fine grained emery paper or sandpaper adhesively secured tothe resilient pads which in turn are adhesively secured to the face of the sliding members. Since the -abrading embers are adhesively secured to the pads, replacement is very inexpensive and quick compared to prior devices.

The resilient pads 86, 88 yield by temporary compressive deformation when in contact with an article 16. The weight of an arm 40, 42 and the respective attached mechanisms including lugs, drive members and the tension exerted by a spring are sufficient to cause the deformation. The yield of pads 86, 88 provides for long life of the abrading members 82, 84 while still achieving good abrading contact. The texture of the abrading members 82, 84 need not be the same but may vary in courseness to provide a sequence of abrasive textures for any chosen abrading operation. In general the width of the pads 86, 88 should be kept narrow for best results with a width of about two inches preferred for both pads and abrading members. This width preserves uniform abrading action.

In FIG. 6 the article 16 has passed under feed roller 18 and first roller bar 28 thereby activating the lifting means which includes the lug 31. Lifting of lug 31 by roller bar 28 slightly raises the liftable, tiltable abrasion arm including the sliding member 40. A slight interference exists between the approaching article 16 and the first abrading member 82. The second roller bar is still in contact with belt 12. The degree of lift and tilt to the lugs by the roller bar is kept small or limited by a tension spring to maintain abrading contact between the abrading member and an article passing beneath it.

In FIG. 7 article 16 has forced itself beneath the abrading member 82 and is undergoing abrasion. The lug 31 is no longer in contact with roller bar 28.

In FIG. 8 article 16 has passed under the second roller bar 29 activating a lifting and tilting means which includes lug 33. Tilting of sliding member 42 would be achieved if article 16 had a tilted surface with respect to the horizontal. Note that surfaces with a triangular shape, i.e. an inverted V shaped cross section would be subject to complete abrasion since each arm would be pulled over each leg of the inverted V and pivot about the pivot point in a see-saw motion.

In the above operation it has been found optimum to provide a large number of transverse abrading strokes to each article for each unit of belt travel. For example, about 14 transverse strokes are recommended for each inch of belt travel.

Article 16, approaching the second abrading member 84, activates the lifting of the second sliding member 42 with similar abrasion as encountered with the first sliding member 40. In this manner an article 16 is de-burred or otherwise treated by the abrading members of the present apparatus.

It will be noted that there is virtually no limit on the smallness of articles which can be placed on the belt for surface treatment. The only limit on largeness is set by the width of the belt.

What is claimed is:

1. An apparatus for abrading flat and triangularly cross sectional articles comprising,

an article carrier belt movable over a fixed path,

liftable, tiltable abrasion arms mounted for motion transversely facing the article carrier belt, said arms each including an abrading member lining the sides of each arm facing articles moving forward on the belt,

lifting means associated with said abrasion arms for orienting the elevation of each arm above an article on the belt to make abrading contact with the surfaces of said article under each arm, said lifting means operable in response to article approach to said arms, and

motive means for advancing said belt and for moving said arms with transverse abrading motion.

2. The apparatus of claim 1 where said arms are arranged in first and second sets of generally equal numbers for opposed connection to said motive means for mutually opposed motion.

3. The apparatus of claim 2 wherein an end of each arm is pivotally connected to a rocker bar with the rocker bar of the first set of arms mounted on an opposite side of the article belt from the rocker bar of the second set of arms.

4. The apparatus of claim 3 wherein the ends of said rocker bars opposite to said pivotaliy connected ends are joined to drive shafts, the drive shafts associated with the oppositely mounted rocker bars of the first and second sets of arms eccentrically connected to the rim of a wheel driven by said motive means thereby providing opposed motion for said first and second sets of arms.

5. The apparatus of claim 3 wherein each of said liftable, tiltable arms comprises,

a drive member rotably cantilevered at one end to said rocker bars and having a central pivotal connection, liftable, tiltable sliding member joined to said drive member at said pivotal connection for tilting in seesaw motion in response to being pulled over triangular shaped surfaces, said sliding member having a face portion extending across the belt and having a pair of lugs disposed on each side of said pivotal connection, said lugs extending outwardly in the direction of belt motion, and

an abrading member lining the face portion of the sliding member.

6. The apparatus of claim 5 wherein the lifting means associated with the arms comprises,

a liftable roller bar placed on said belt under said lugs for lifting said lugs when an article is carried on said belt under the roller bar with the degree of lift limited to maintain abrading contact between said abrading member and said article.

7. The apparatus of claim 5 wherein an article on said belt under an arm receives at least ten transverse abrading strokes from an arm during an inch of article travel of said belt.

8. The apparatus of claim 6 wherein the amount of abrading contact maintained between said article and said abrading member is set by a spring connected at the end of each drive member opposite the end from which said drive member is cantilevered.

9. The apparatus of claim 1 wherein said article carrier belt has spaced surface cleats for frictionally engaging articles placed thereon and for allowing fluid flow therebetween.

10. The apparatus of claim 1 further defined by an abrading lubrication means comprising,

fluid lubricant sources disposed above said belt and colinear therewith, said sources directed downward toward said belt, and

a fluid lubricant sink disposed below said belt and said sources, extending in area beyond the edges of said belt for catching fluid run-ofl from said belt.

References Cited UNITED STATES PATENTS 888,816 5/1908 Kaeser 51-61 1,405,639 2/1922 Stuart 5161 3,648,412 3/1972 Hathaway 51-61 FOREIGN PATENTS 96,885 9/1939 Sweden 5161 CHARLES W. LANTHAM, Primary Examiner G. P. CROSBY, Assistant Examiner

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