US3731432A - Apparatus for removing wustite scale centrifugal blasting - Google Patents
Apparatus for removing wustite scale centrifugal blasting Download PDFInfo
- Publication number
- US3731432A US3731432A US00215616A US3731432DA US3731432A US 3731432 A US3731432 A US 3731432A US 00215616 A US00215616 A US 00215616A US 3731432D A US3731432D A US 3731432DA US 3731432 A US3731432 A US 3731432A
- Authority
- US
- United States
- Prior art keywords
- workpiece
- treating chamber
- path
- treated
- abrasive particles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
- B24C1/08—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for polishing surfaces, e.g. smoothing a surface by making use of liquid-borne abrasives
- B24C1/086—Descaling; Removing coating films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C3/00—Abrasive blasting machines or devices; Plants
- B24C3/08—Abrasive blasting machines or devices; Plants essentially adapted for abrasive blasting of travelling stock or travelling workpieces
- B24C3/10—Abrasive blasting machines or devices; Plants essentially adapted for abrasive blasting of travelling stock or travelling workpieces for treating external surfaces
- B24C3/14—Apparatus using impellers
Definitions
- Anobject of this invention is to provide apparatus for descaling to replace the conventional pickling process and apparatus.
- a further object of this invention is to provide such apparatus which utilizes improved centrifugal blasting techniques for the removal of converted wustite.
- wustite scale is removed from iron or steel products by blasting fine grit from a centrifugal blast wheel which rotates at low speed against the product at an angle thereto, with the grit having sharp edges.
- Preferred parameters for the novel method is to project the grit at an angle between 45 and 75 and preferably 60 with the blast wheel being rotated at a speed of 1,500 rpm to 2,000 rpm and preferably at 1,750 rpm.
- the grit is also preferably between 0.004 and 0.015 inch long.
- FIG. 1 is a block diagram showing the general process steps of this invention
- FIG. 2 is a schematic showing of a prior art type arrangement wherein the blast particles are directed perpendicular to the plate;
- FIG. 3 is a schematic showing similar to FIG. 2 of the inventive method
- FIG. 4 is a schematic illustration of a prior art type arrangement wherein spherical shot is used as the blast particles
- FIG. 5 is a schematic arrangement similar to FIG. 4 of the inventive method which utilizes sharp angled grit;
- FIG. 6 is a side elevational view showing a portion of the apparatus of the present invention in section
- FIG. 7 is an end elevational view of the apparatus of FIG. 6 in section
- FIG. 8 is a partial end elevational view of the apparatus of FIG. 7 in section;
- FIG. 9 is a detailed view along line 99 of FIG. 8;
- FIG. 10 is a detailed view in section of a portion of the apparatus.
- FIG. 11 is a schematic view showing the blast pattern.
- FIG. 1 illustrates the general process steps utilized in this invention. As indicated therein the general sequence of steps is similar to that suggested by U.S. Pat. No. 3,166,841, the details of which are incorporated herein by reference thereto.
- the iron or steel product containing magnetite scale is first conveyed into a furnace 10 wherein, in accordance with the patent, the magnetite is converted to wustite.
- the product is then quickly cooled in cooling chamber 12 so that the wustite will not reconvert. Thereafter, the wustite scale is removed at blast station 14.
- the blasting techniques utilized at blast station 14 are the particular subject matter of this invention.
- FIGS. 2 and 4 are included to illustrate the results which would be obtained if certain of the prior art practices were attempted to be included in the novel method.
- FIG. 4 illustrates the affects obtained from using spherical shot rather than the fine sharp angled grit.
- the shot 18 strikes the wustite scale 20 but tends to embed a portion 22 of the scale at the bottom of the crater 24 formed by the shot. Because of this embedding action subsequent impacts from other shot does not remove this scale.
- FIG. 5 shows how with the inventive apparatus the disadvantages illustrated in FIG. 4 are obviated.
- sharp angular grit 26 is utilized for the' wustite removal. Tests have shown that this sharp angular grit hitting with sufficient force to remove the wustite scale 28 was effective in getting the sheet or plate 16 percent clean. Although the theory behind and should be propelled with just enough force to remove the scale.
- the present invention recognizes that since wustite is more easily removed than magnetite, it
- the clean-rate is thus dependent upon the number of impacts.
- the number of impacts per horsepower is thereby increased by the ratio of (2,250/ 1 ,750)".
- the impacts per square inch per second is 1,000 for 2,250 rpm
- the impacts at 1,750 is (1,000) (2,250/1,750) or 1,650 impacts/in. /sec.
- the theoretical cleaning rate for the wustite would be increased approximately at 1.6 times the rate at standard wheel speed. This, coupled with the fact that wustite is easier to remove than magnetite gives a cleaning rate of four times faster than the standard rate for removing magnetite scale.
- the grit is projected in a wave 32 which then ricochets as designated by the reference numeral 34 clear of the succeeding waves of abrasive from the vanes.
- the attainment of this angular projection is preferably accomplished. by utilizing a recently developed direct drive wheel which is illustrated and described in copending application Ser. No. 687,701, filed Dec. 4, 1967, now US. Pat. No. 3,521,406, issued July 21, 1970, the details of which are incorporated herein by reference thereto.
- This universally mounted wheel is readily adapted for obtaining the proper angular projection of the grit. It has been found that with the improved wustite removal method it is possible to completely clean converted steel at a rate of V2 HP/ft /min.
- the number of impacts per HP is increased by 1.6 times, and angling the wheel 60 to the horizontal results in preventing abrasive blinding. If smut remains on the cleaned plate it can be removed by high pressure water spray although a dry method of removal is preferable.
- the inventive apparatus Among the various advantages with the inventive apparatus is the'ecological advantage of eliminating the acid disposal problem. Additionally, less floor space is required, as well as reduced costs as compared with a pickle line. Moreover, the direct wheel drive 30 enables less expense mounting and movement mechanism and thus less expense installation. By locating the wheel 30 inside a cabinet in combination with the reduced speed, results in significantly less noise. Finally the maintenance is less at reduced shot'velocity.
- a conventional or standard blasting wheel such as the type having about 19% inch diameter
- a normal speed of 2,250 rpms which corresponds to a velocity of projected grit of 240 to about 260 feet per second
- a low speed in the range of 1,500 rpms to 2,000 rpms which correspond to a velocity of projected shot from about feet per second to 210 feet per second.
- the wheel is rotated at about 1,750 rpms which corresponds to a speed of projected shot of about to 200 feet per second.
- grit particles which are harder than conventional shot. It is believed that the harder grit cleans better due to sharper and harder edges. The soft grit seems to pick up microscopic particles of scale and redeposit them on the plate; whereas, the hard grit does not seem to pick up the scale so that redepositing of the scale is precluded.
- Abrasive particles which have been found suitable for the practice of the present invention range in hardness between 55 and 65 Rockwell, and preferably between 58 and 64 Rockwell.
- FIGS. 6 and 7 are illustrative of apparatus that can be used to carry out the process of the'present invention.
- a treating chamber or housing 42 of an elongated rectangular shape is sufficiently wide to accommodate a workpiece 44 such as strips of sheet metal of various widths.
- Each end wall of the housing 42 is provided with an opening 46 so that workpiece 44 may be continuously fed in a longitudinal direction through the housing 42. Sealing means can be conveniently provided around each opening to prevent the escape of abrasive particles.
- the workpiece 44 is supported by suitable means such as a plurality of rollers 48 within the housing 42.
- the workpiece 44 is a coil 50 of sheet metal which is mounted for rotation.
- the coil 50 is unwound and drawn through the treating chamber 42 by suitable means (not shown) such as a conventional coiling apparatus at the exit end.
- a plurality of elongated support members 52 extend across the treating chamber 42 in a direction transverse to the movement of the workpiece 44 therethrough. Support members 52 are provided above and below the path of travel of the workpiece 44 through the treating chamber 42 for supporting blast wheels 54. As illustrated in detail in FIG. 8 and FIG. 10, each of the support members 52 is slidably supported by housing 42 for back and forth movement in a direction transverse to the direction of movement of the workpiece 44 through the treating chamber 42.
- Each mounting member 52 includes portions extending exterior to respective side walls 58 of housing 42 through suitable openings 60. Outer housings 62 which support rollers 56 provide closures at either end of the support member 52.
- a plurality of rollers 56 which are rotatably mounted exterior to the housing 42 support respective exterior portions of supporting members 52. his also contemplated that the support members 52 can be mounted in a cantilevered fashion at one end exterior to the housing 42.
- suitable means such as hydraulic power device 64 is provided for moving the support member 52 back and forth.
- One end of the power device 64 is mounted to an end wall 66 of one of the outer housings 62 while the other end is mounted to the support member 52.
- Other conventional means can be used to effect the movement of the support member 52 such as a driven pinion gear connected to a rack mounted on an exterior portion of the support member 52.
- Seals 65. are conveniently provided for preventing the escape of ricocheting abrasive particles from the treating chamber 42 and reduce the wear of parts which would otherwise be exposed.
- Each support member 52 is positioned above and others below the path of travel of the workpiece 44. Each support member 52 is spaced from and lies in a plane substantially parallel to the surface of the workpiece 44 to be treated.
- a blasting wheel 54 which projects abrasive particles toward the workpiece 44 in a path transverse to the direction of movement of the workpiece 44 is mounted on each support member 52.
- the blasting wheels 54 are mounted to the support members 52 in such a manner that combined blasting patterns of the blasting wheels 54 provide a substantially even treatment of both the top and bottom working surface of workpiece 44. As illustrated in FIG. 11, the blasting patterns or paths of a pair of blasting wheels 54 overlap to give complete coverage of the work.
- An upper pair of blasting wheels 54 are preferably rotated in opposite directions to effect an overlapping blast pattern and even treatment of the workpiece 44. Also, the lower pair of the blasting wheels 54 are similarly positioned and rotated.
- the coverage of the working surfaces of the workpiece 44 can be maximized while the amount of projected abrasive wasted or not striking the working surfaces can be minimized by moving the support members 52 back and forth to widen or narrow the combined paths of the projected abrasive.
- a pair of the blasting wheels 54 directed at a particular surface being treated, either upper or lower, are moved toward each other.
- the same blasting wheels 54 are away from each other.
- FIG. 8 illustrates the movement of a blasting wheel 54 from a solid line to a dotted line position and the resulting shift in blast pattern to accommodate workpiece 44 of a smaller width.
- this adjustment could be automatically made by providing means at an opening 46 through which the workpiece 44 is fed to sense the width of the workpiece 44.
- the sensing means would transmit the information to a controller which would actuate the hydraulic power devices'64 to movethe support member 52 to adjust the blasting pattern.
- Each of the blasting or centrifugal throwing wheels 54 rotate about an axis within a plane substantially vertical and parallel to the direction of movement of the workpiece 44 through the treating chamber 42 on a shaft of a motor which is enclosed in a motor housing 70.
- the axis of rotation is non-parallel to the surface of the workpiece 44 to be treated, preferably at an angle between 15 and 45 and even more preferably at an angle of about 30 with respect to the surface.
- this mounting arrangement is achieved by pivotally mounting the motor or motor housing on brackets 72 which depend from the support member 52.
- the motor 70 is mounted for movement about a substantially horizontal axis which is transverse or substantially normal to the direction of travel of the workpiece 44.
- Means are provided for releasably securing the motor 70 to the brackets 72 to fix the angle at which the abrasive particles are thrown at the work surface of the workpiece 44. As illustrated in FIG. 9, this is in the form of a nut 74 which is tightened to hold the motor 70 in a fixed position.
- Other means such as a notched disc and plunger arrangement for manual operation or spaced stops and a limit pin for power actuation can be conveniently provided.
- the treating chamber or housing 42 includes a plurality of compartments each having a pair of blasting wheels 54 mounted above and below the workpiece 44.
- Each compartment includes a main hopper 76 which delivers abrasive particles to conduits 78 which are connected to the blasting wheels 54.
- Spent abrasive particles are collected in the tapered portion 80 at the bottom of the treating chamber 42 and ultimately recycled back to hopper 76 throughconventional elevating device 82 and separator 84.
- the separator 84 removes an unusable portion from a usuable portion of abrasive particles which is recycled.
- a plurality of devices, 84 for blowing debrisand spent abrasive off the top surface of the workpiece 44 are provided. These devices 84 discharge air under pressure onto the top surface so the debris and spent abrasive fall into the tapered portion 80. The abrasive particles projected toward the bottom surface of the workpiece 44 and fall into the tapered portion 80.
- An apparatus for treating a workpiece comprising a treating chamber; means supporting a workpiece for movement along a path in a given direction through said treating chamber; a plurality of elongated support members extending across said treating chamber transverse to the path of movement of the workpiece, said members being mounted for sliding movement back and forth across said treating chamber; a centrifugal throwing wheel mounted on each of said members and adapted to project abrasive particles in a path toward the workpiece; and means for moving said members back and forth across said treating chamber for varying the projected path of abrasive particles.
- Apparatus according to claim 2 wherein a first, second, third, and fourth centrifugal throwing wheels are mounted on said first, second, third and fourth mounting members, respectively, to effect an even treatment of the surface of the workpiece to be treated.
- Apparatus according to claim 4 wherein said means for moving said members back and forth is adapted to move said first and second throwing wheels toward and away from each other and said third and fourth centrifugal throwing wheels toward and away from each other thereby narrowing or widening the projected path of abrasive particles.
- each centrifugal throwing wheel rotates about an axis within a plane substantially vertical and parallel to the direction of movement of the workpiece through the treating chamber.
- Apparatus according to claim 7 wherein said axis is at an angle of about 30 with respect to the surface to be treated.
- Apparatus according to claim 6 including a bracket depending from each supporting member, a motor for driving said centrifugal throwing wheel, and means for adjustably mounting each motor on a respective bracket for movement about an axis normal to the direction of movement of the workpiece.
- Apparatus according to claim 2 including means for supplying treating particles to each centrifugal throwing wheel.
- Apparatus according to claim 2 for treating a metal sheet having a top and bottom surface to be treated, said treating chamber being an elongated rectangular shape having side walls and end walls, said end walls having openings for permitting the metal sheet to pass through said treating chamber, and means for continuously feeding the metal sheet through said treating chamber.
Abstract
Description
Claims (15)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US21561672A | 1972-01-05 | 1972-01-05 |
Publications (1)
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US3731432A true US3731432A (en) | 1973-05-08 |
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US00215616A Expired - Lifetime US3731432A (en) | 1972-01-05 | 1972-01-05 | Apparatus for removing wustite scale centrifugal blasting |
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Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4566230A (en) * | 1982-03-08 | 1986-01-28 | Kennecott Corporation | Impact blasting system for etching metal surfaces |
US4999956A (en) * | 1986-01-31 | 1991-03-19 | Watts W David | Ricochet metal strip cleaner |
US5107629A (en) * | 1989-11-09 | 1992-04-28 | The Celotex Corporation | Texturing of acoustical mineral fiberboard with wheel blast machine |
US20080182486A1 (en) * | 2006-09-14 | 2008-07-31 | The Material Works, Ltd. | Slurry Blasting Apparatus for Removing Scale From Sheet Metal |
US20090227184A1 (en) * | 2006-09-14 | 2009-09-10 | The Material Works, Ltd. | Method of Producing Rust Inhibitive Sheet Metal Through Scale Removal with a Slurry Blasting Descaling Cell |
US20110009034A1 (en) * | 2006-09-14 | 2011-01-13 | The Material Works, Ltd. | Method of Producing Rust Inhibitive Sheet Metal Through Scale Removal with a Slurry Blasting Descaling Cell Having Improved Grit Flow |
US20110130075A1 (en) * | 2006-09-14 | 2011-06-02 | The Material Works, Ltd. | Method of Producing Rust Inhibitive Sheet Metal Through Scale Removal with a Slurry Blasting Descaling Cell Having Improved Grit Flow |
CN102699822A (en) * | 2012-05-25 | 2012-10-03 | 福耀集团(上海)汽车玻璃有限公司 | Method for eliminating plated layer on sputtering baffle of vacuum coating |
EP3184242A4 (en) * | 2014-08-20 | 2018-04-18 | NHK Spring Co., Ltd. | Vertical motion impeller-type shot peening device and coil spring |
Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2015875A (en) * | 1933-07-12 | 1935-10-01 | Francis P Sloan | Preparation of concrete floorings to receive topping layers |
US2318432A (en) * | 1940-09-13 | 1943-05-04 | Youngstown Sheet And Tube Co | Method and apparatus for descaling strip material |
US2391499A (en) * | 1941-06-25 | 1945-12-25 | Bertha L Yoder | Process of and apparatus for operating on sheet metal |
US2669810A (en) * | 1950-01-28 | 1954-02-23 | Eppler | Method and apparatus for graining lithographic plates |
US2777256A (en) * | 1954-12-20 | 1957-01-15 | Cline Electric Mfg Co | Apparatus for graining surfaces |
US3166841A (en) * | 1960-11-24 | 1965-01-26 | South African Iron & Steel | Descaling |
US3348339A (en) * | 1965-05-24 | 1967-10-24 | Pangborn Corp | Abrasive blasting wheels and vanes |
US3362109A (en) * | 1964-10-27 | 1968-01-09 | Ralph O. Wallace | Treating apparatus and method |
US3368308A (en) * | 1964-11-03 | 1968-02-13 | Pangborn Corp | Centrifugal blasting apparatus |
US3392491A (en) * | 1965-08-03 | 1968-07-16 | Textron Inc | Particle segregating system |
US3521406A (en) * | 1967-12-04 | 1970-07-21 | Carborundum Co | Workpiece treating apparatus |
-
1972
- 1972-01-05 US US00215616A patent/US3731432A/en not_active Expired - Lifetime
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2015875A (en) * | 1933-07-12 | 1935-10-01 | Francis P Sloan | Preparation of concrete floorings to receive topping layers |
US2318432A (en) * | 1940-09-13 | 1943-05-04 | Youngstown Sheet And Tube Co | Method and apparatus for descaling strip material |
US2391499A (en) * | 1941-06-25 | 1945-12-25 | Bertha L Yoder | Process of and apparatus for operating on sheet metal |
US2669810A (en) * | 1950-01-28 | 1954-02-23 | Eppler | Method and apparatus for graining lithographic plates |
US2777256A (en) * | 1954-12-20 | 1957-01-15 | Cline Electric Mfg Co | Apparatus for graining surfaces |
US3166841A (en) * | 1960-11-24 | 1965-01-26 | South African Iron & Steel | Descaling |
US3362109A (en) * | 1964-10-27 | 1968-01-09 | Ralph O. Wallace | Treating apparatus and method |
US3368308A (en) * | 1964-11-03 | 1968-02-13 | Pangborn Corp | Centrifugal blasting apparatus |
US3348339A (en) * | 1965-05-24 | 1967-10-24 | Pangborn Corp | Abrasive blasting wheels and vanes |
US3392491A (en) * | 1965-08-03 | 1968-07-16 | Textron Inc | Particle segregating system |
US3521406A (en) * | 1967-12-04 | 1970-07-21 | Carborundum Co | Workpiece treating apparatus |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4566230A (en) * | 1982-03-08 | 1986-01-28 | Kennecott Corporation | Impact blasting system for etching metal surfaces |
US4999956A (en) * | 1986-01-31 | 1991-03-19 | Watts W David | Ricochet metal strip cleaner |
US5107629A (en) * | 1989-11-09 | 1992-04-28 | The Celotex Corporation | Texturing of acoustical mineral fiberboard with wheel blast machine |
US20080182486A1 (en) * | 2006-09-14 | 2008-07-31 | The Material Works, Ltd. | Slurry Blasting Apparatus for Removing Scale From Sheet Metal |
US20090227184A1 (en) * | 2006-09-14 | 2009-09-10 | The Material Works, Ltd. | Method of Producing Rust Inhibitive Sheet Metal Through Scale Removal with a Slurry Blasting Descaling Cell |
US20110009034A1 (en) * | 2006-09-14 | 2011-01-13 | The Material Works, Ltd. | Method of Producing Rust Inhibitive Sheet Metal Through Scale Removal with a Slurry Blasting Descaling Cell Having Improved Grit Flow |
US20110130075A1 (en) * | 2006-09-14 | 2011-06-02 | The Material Works, Ltd. | Method of Producing Rust Inhibitive Sheet Metal Through Scale Removal with a Slurry Blasting Descaling Cell Having Improved Grit Flow |
US8062095B2 (en) | 2006-09-14 | 2011-11-22 | The Material Works, Ltd. | Method of producing rust inhibitive sheet metal through scale removal with a slurry blasting descaling cell having improved grit flow |
US8066549B2 (en) | 2006-09-14 | 2011-11-29 | The Material Works, Ltd. | Method of producing rust inhibitive sheet metal through scale removal with a slurry blasting descaling cell having improved grit flow |
US8074331B2 (en) * | 2006-09-14 | 2011-12-13 | The Material Works, Ltd. | Slurry blasting apparatus for removing scale from sheet metal |
US8128460B2 (en) | 2006-09-14 | 2012-03-06 | The Material Works, Ltd. | Method of producing rust inhibitive sheet metal through scale removal with a slurry blasting descaling cell |
CN102699822A (en) * | 2012-05-25 | 2012-10-03 | 福耀集团(上海)汽车玻璃有限公司 | Method for eliminating plated layer on sputtering baffle of vacuum coating |
EP3184242A4 (en) * | 2014-08-20 | 2018-04-18 | NHK Spring Co., Ltd. | Vertical motion impeller-type shot peening device and coil spring |
US10315287B2 (en) | 2014-08-20 | 2019-06-11 | Nhk Spring Co., Ltd. | Vertical motion impeller-type shot peening device and coil spring |
US10836013B2 (en) | 2014-08-20 | 2020-11-17 | Nhk Spring Co., Ltd. | Vertical motion impeller-type shot peening device and coil spring |
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Legal Events
Date | Code | Title | Description |
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AS | Assignment |
Owner name: KENNECOTT CORPORATION Free format text: MERGER;ASSIGNORS:BEAR CREEK MINING COMPANY;BEAR TOOTH MINING COMPANY;CARBORUNDUM COMPANY THE;AND OTHERS;REEL/FRAME:003961/0672 Effective date: 19801230 |
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AS | Assignment |
Owner name: NATIONAL WESTMINSTER BANK USA, 592 FIFTH AVENUE, N Free format text: SECURITY INTEREST;ASSIGNOR:PANGBORN CORPORATION, A CORP. OF DE.;REEL/FRAME:004576/0188 Effective date: 19860724 |
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Owner name: PANGBORN CORPORATION, PANGBORN BLVD., HAGERSTOWN, Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:KENNECOTT CORPORATION;REEL/FRAME:004614/0421 Effective date: 19860725 |
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AS | Assignment |
Owner name: MERRILL LYNCH INTERFUNDING INC., NEW YORK Free format text: SECURITY INTEREST;ASSIGNOR:PANGBORN CORPORATION;REEL/FRAME:005237/0297 Effective date: 19891211 |