US2027308A - Manufacture of abrasive articles - Google Patents

Manufacture of abrasive articles Download PDF

Info

Publication number
US2027308A
US2027308A US576415A US57641531A US2027308A US 2027308 A US2027308 A US 2027308A US 576415 A US576415 A US 576415A US 57641531 A US57641531 A US 57641531A US 2027308 A US2027308 A US 2027308A
Authority
US
United States
Prior art keywords
particles
carrier
terminals
abrasive
electrode
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
Application number
US576415A
Inventor
Elmer C Schacht
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Abrasives Inc
Original Assignee
Behr Manning Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Behr Manning Corp filed Critical Behr Manning Corp
Priority to US576413A priority Critical patent/US2245301A/en
Priority to US576415A priority patent/US2027308A/en
Priority to US576414A priority patent/US2082182A/en
Priority to GB2971/32A priority patent/GB396385A/en
Priority to DEB154261D priority patent/DE590459C/en
Priority to FR731457D priority patent/FR731457A/en
Application granted granted Critical
Publication of US2027308A publication Critical patent/US2027308A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
    • B24D11/001—Manufacture of flexible abrasive materials
    • B24D11/005—Making abrasive webs
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S101/00—Printing
    • Y10S101/37—Printing employing electrostatic force

Definitions

  • My invention relatesto the manufacture of abrasive articles and particularly flexible abrasive material such as sand paper wherein the abrasive particles are applied to the adhesive surface of a backing or carrier.
  • the primary object of the invention is to produce a sand paper having optimum cutting efiiciency, and wherein the particles are uniformly dispersed, oriented and stratifled upon the surface of the backing.
  • the invention is applicable to the manufacture of both closed coated and open coated sand paper.
  • I employ a hopper ill, in which are disposed the abrasive particles.
  • a feed roller or gate H is disposed at the mouth of the hopper, so that the particles may be fed in controlled amounts gravitationally.
  • the particles will comprise the usual mixture, namely of under grade, control grade" and "above grade, in which the control grade usually predominates.
  • a carrier or backing I! of paper, cloth, or laminated structure of the two is arranged to be continuously moved in'a position over suitable supporting rollers H to receive the sand particles fed from the hopper.
  • This backing or carrier has its surface coated with a suitable adhesive as at l3 and travels in the direction indicated by the arrows.
  • an electrode, H Disposed below the carrier I3 is an electrode, H, which will be suitably charged from a source" of high potential.
  • the electrode will preferably carry a negative charge and will comprise arbar, cylinder or other desired form of element, preferably of the length to extend across the transverse dimension of the web It.
  • terminals I5 may be charged and the terminal !4 grounded. I may also use a pair of charged 5 terminals i5 and a pair of grounded terminals 14 or vice versa.
  • I may also employ reversely charged terminals wherein the electrode or electrodes below the web will be charged negatively and the electrode or electrodes above the web are charged positively, from a suitable source of high potential, or vice versa.
  • the terminals l5 are preferably disposed out of the normal gravitational path of the sand column and at a suitable distance, depending upon the voltage employed, from the electrode It as to produce a thoroughly satisfactory electrical field.
  • the electrode or ground 14 is preferably placed in close proximity to the under surface of thebacking as shown, but the spacing of the various terminals or electrodes with respect to each other and to the carrier may be varied in accordance with the prodnot being made, the strength of the field and the nature of the particles.
  • the intensity of the electrical field will be greatest at and about the point where the lines of force created between the terminals l5 and the electrode l4 converge, namely at and about the sand column where it contacts with the web.
  • the particles are attracted to the backing by the electrode II, at the same time acquiring a charge which causes them to be mutually repellent and hence shower or fan out.
  • the intensity of the field is greatest at and about the point of contact of the sand column with the web and I am enabled to obtain (a) a uniform dispersion to produce a level sand distribution having a maximum number of cutting points, (b) an orientation such that the particles are positioned with their longest axes and sharpest edges producing a maximum cutting effect, and (c) a stratification or classification whereby the coarser fractions are disposed in the top plane where they produce an optimum abrading result.
  • shields I6 disposed adjacent the backing and whichextend across the transverse area thereof. These shields in some cases are useful to confine the particles in the event there is an undue fanningout or showering and are preferably made of insulated material or suitably insulated. I also place beneath the electrode M a shield I! of insulated material and the respective shields cooperate in addition to confining the particles, to enhance the intensity of the electrical field produced through the medium of the several electrodes or terminals. These shields, of course, may be omitted but I find them very satisfactory for both functions recited.
  • the electrodes may be arranged in various ways and their spacing with respect to each other and to the backing, may be varied at will in accordance with the character of the coating desired, the strength of the field and the particular article which is being made.
  • the invention enables a very careful and accurate control to the end that a uniform dispersion, orientation and Stratification are obtained and an article having optimum abrading efiiciency is formed.
  • an apparatus of the class described comprising a feeding means for abrasive particles, means for supporting a carrier having an adhesive surface to be coated with said particles below said feeding means, and means for forming an electrical field comprising terminals on one side of the carrier between which the particles pass in their path to the carrier and a terminal of opposite polarity on the other side of the carrier disposed substantially intermediate the said first mentioned terminals, whereby to narrow and intensify the field at the point of disposition of the particles upon the carrier.
  • An apparatus of the class described comprising a gravity feeding means for abrasive par- 5 ticles, means for supporting a backing having an adhesive surface to be coated with said particles, an electrode disposed in close proximity beneath the backing when the latter is supported on said means, and a pair of spaced terminals 10 disposed on the other side of the backing and creating with said electrode a substantially V- shaped electrical field embracing the abrasive column at and about its point of contact with the carrier.
  • An apparatus of the class described comprising a feeding means for abrasive particles, means for supporting and continuously moving a carrier having an adhesive surface to be coated with said particles, a terminal disposed in close proximity beneath said carrier when supported on said means, and a pair of spaced terminals disposed above said carrier between which the particles are adapted to pass in their path to the carrier, the respective terminals creating a 26 substantially V-shaped electrical field having its greatest intensity at and about the point of contact of the abrasive column with the carrier.
  • An apparatus of the class described comprising a feeding means for abrasive particles, 30 means for supporting and continuously moving a carrier having an adhesive surface to be coated with said particles, a terminal disposed in close proximity beneath said carrier when supported on said means, and a pair of spaced terminals disposed above said carrier between which the particles are adapted to pass in their path to the carrier, the respective terminals creating a substantially V-shaped electrical field having its greatest intensity at and about the point of contact of the abrasive column with the carrier, and shields of insulated material disposed adjacent the carrier and about the electrode beneath the carrier.

Description

Jan. 7, 1936. E. c. SCHACHT IANUFACTURE OF ABRASIVE ARTICLES Original Filed Nov; 20, 1931' Cir Patented Jan. 7, 1936 UNITED STATES PATENT OFFICE MANUFACTURE OF ABRASIVE ARTICLES Application November 20, 1931, Serial No. 576,415 Renewed January 7, 1935 Claims.
My invention relatesto the manufacture of abrasive articles and particularly flexible abrasive material such as sand paper wherein the abrasive particles are applied to the adhesive surface of a backing or carrier.
The primary object of the invention is to produce a sand paper having optimum cutting efiiciency, and wherein the particles are uniformly dispersed, oriented and stratifled upon the surface of the backing.
It is a further object of the invention to control the positions of the particles upon the carrier by means of an electrical field which will embrace the sand column adjacent to and about its point of contact with the carrier.
In accordance with the present inventio wherein the positions of the sand particles is very definitely controlled, I am enabled to obtain a) a uniform dispersion to produce a level sand distribution having the maximum number of cutting points, (b) an orientation of the particles such that the longest axes and sharpest edges produce maximum cutting effect, and (c) a stratification or classification whereby the coarser fractions are positioned in the top plane where they produce maximum abrading effect.
The invention is applicable to the manufacture of both closed coated and open coated sand paper.
In the drawing, the single figure is a diagrammatic view of the invention.
In carrying out the invention, I employ a hopper ill, in which are disposed the abrasive particles. A feed roller or gate H is disposed at the mouth of the hopper, so that the particles may be fed in controlled amounts gravitationally.
The particles will comprise the usual mixture, namely of under grade, control grade" and "above grade, in which the control grade usually predominates. I
A carrier or backing I! of paper, cloth, or laminated structure of the two is arranged to be continuously moved in'a position over suitable supporting rollers H to receive the sand particles fed from the hopper. This backing or carrier has its surface coated with a suitable adhesive as at l3 and travels in the direction indicated by the arrows. Disposed below the carrier I3 is an electrode, H, which will be suitably charged from a source" of high potential. The electrode will preferably carry a negative charge and will comprise arbar, cylinder or other desired form of element, preferably of the length to extend across the transverse dimension of the web It.
On the other side of the carrier, there is placed a pair of opposed grounded terminals l5.
At this point, it should be understood that the terminals I5 may be charged and the terminal !4 grounded. I may also use a pair of charged 5 terminals i5 and a pair of grounded terminals 14 or vice versa.
In lieu of these expedients, I may also employ reversely charged terminals wherein the electrode or electrodes below the web will be charged negatively and the electrode or electrodes above the web are charged positively, from a suitable source of high potential, or vice versa.
Referring to the drawing, the terminals l5 are preferably disposed out of the normal gravitational path of the sand column and at a suitable distance, depending upon the voltage employed, from the electrode It as to produce a thoroughly satisfactory electrical field. The electrode or ground 14 is preferably placed in close proximity to the under surface of thebacking as shown, but the spacing of the various terminals or electrodes with respect to each other and to the carrier may be varied in accordance with the prodnot being made, the strength of the field and the nature of the particles.
In the embodiment shown, the intensity of the electrical field will be greatest at and about the point where the lines of force created between the terminals l5 and the electrode l4 converge, namely at and about the sand column where it contacts with the web.
By employing such a construction the particles are attracted to the backing by the electrode II, at the same time acquiring a charge which causes them to be mutually repellent and hence shower or fan out.
. By reason of the electrical field created in any of the several ways described, the control of the deposition of the particles upon the web is very efficiently cared for.
Thus the intensity of the field is greatest at and about the point of contact of the sand column with the web and I am enabled to obtain (a) a uniform dispersion to produce a level sand distribution having a maximum number of cutting points, (b) an orientation such that the particles are positioned with their longest axes and sharpest edges producing a maximum cutting effect, and (c) a stratification or classification whereby the coarser fractions are disposed in the top plane where they produce an optimum abrading result.
It will be understood that with the feed of the particles regulated from the hopper by means 0! the gate H to accord with the character of sand paper it is desired to produce, that the particles will be'propelled by gravity to a point adjacent the continuously moving backing above the electrode l4 and between the terminals I5, reaching the paper or web at the point of conversion of the lines of force created by the electrodes or terminals and which is the point of greatest electrical intensity. Thus a field is produced at and about the sand column which creates the repellent action of the particles and causes them to fan-out in a definite manner, depending upon the strength of the field which may be regulated to alter the effect.
I have illustrated in the drawing two shields I6 disposed adjacent the backing and whichextend across the transverse area thereof. These shields in some cases are useful to confine the particles in the event there is an undue fanningout or showering and are preferably made of insulated material or suitably insulated. I also place beneath the electrode M a shield I! of insulated material and the respective shields cooperate in addition to confining the particles, to enhance the intensity of the electrical field produced through the medium of the several electrodes or terminals. These shields, of course, may be omitted but I find them very satisfactory for both functions recited.
While I have referred herein to sand as the abrasive medium, it will be understood that other abrasives of a particle nature are operable in accordance with this invention.
The electrodes, as stated, may be arranged in various ways and their spacing with respect to each other and to the backing, may be varied at will in accordance with the character of the coating desired, the strength of the field and the particular article which is being made.
It will be understood that the invention enables a very careful and accurate control to the end that a uniform dispersion, orientation and Stratification are obtained and an article having optimum abrading efiiciency is formed.
What I claim is:
1. In an apparatus of the class described comprising a feeding means for abrasive particles, means for supporting a carrier having an adhesive surface to be coated with said particles below said feeding means, and means for forming an electrical field comprising terminals on one side of the carrier between which the particles pass in their path to the carrier and a terminal of opposite polarity on the other side of the carrier disposed substantially intermediate the said first mentioned terminals, whereby to narrow and intensify the field at the point of disposition of the particles upon the carrier.
2. An apparatus of the class described comprising a gravity feeding means for abrasive par- 5 ticles, means for supporting a backing having an adhesive surface to be coated with said particles, an electrode disposed in close proximity beneath the backing when the latter is supported on said means, and a pair of spaced terminals 10 disposed on the other side of the backing and creating with said electrode a substantially V- shaped electrical field embracing the abrasive column at and about its point of contact with the carrier.
3. An apparatus of the class described comprising a feeding means for abrasive particles, means for supporting and continuously moving a carrier having an adhesive surface to be coated with said particles, a terminal disposed in close proximity beneath said carrier when supported on said means, and a pair of spaced terminals disposed above said carrier between which the particles are adapted to pass in their path to the carrier, the respective terminals creating a 26 substantially V-shaped electrical field having its greatest intensity at and about the point of contact of the abrasive column with the carrier.
4. An apparatus of the class described comprising a feeding means for abrasive particles, 30 means for supporting and continuously moving a carrier having an adhesive surface to be coated with said particles, a terminal disposed in close proximity beneath said carrier when supported on said means, and a pair of spaced terminals disposed above said carrier between which the particles are adapted to pass in their path to the carrier, the respective terminals creating a substantially V-shaped electrical field having its greatest intensity at and about the point of contact of the abrasive column with the carrier, and shields of insulated material disposed adjacent the carrier and about the electrode beneath the carrier.
5. In an apparatus of the class described comprising a feeding means for'abrasive particles, means for supporting a carrier having an adhesive surface to be coated with said particles,
and means for forming an electrical field comprising terminals of opposite polarity on opposite sides of the carrier, said terminals cooperating to narrow and intensify the field and converge the same at the point of disposition of the particles upon the carrier.
ELMER c. SCHACHT. 56
US576415A 1931-11-20 1931-11-20 Manufacture of abrasive articles Expired - Lifetime US2027308A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US576413A US2245301A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles
US576415A US2027308A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles
US576414A US2082182A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles
GB2971/32A GB396385A (en) 1931-11-20 1932-02-01 Improved process of and apparatus for the manufacture of abrasive articles
DEB154261D DE590459C (en) 1931-11-20 1932-02-07 Manufacture of sandpaper or the like by applying abrasive grains to a carrier provided with adhesive under the influence of an electric field
FR731457D FR731457A (en) 1931-11-20 1932-02-16 Improvements in processes and equipment for the production of abrasives

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US576415A US2027308A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles

Publications (1)

Publication Number Publication Date
US2027308A true US2027308A (en) 1936-01-07

Family

ID=24304327

Family Applications (3)

Application Number Title Priority Date Filing Date
US576413A Expired - Lifetime US2245301A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles
US576414A Expired - Lifetime US2082182A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles
US576415A Expired - Lifetime US2027308A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles

Family Applications Before (2)

Application Number Title Priority Date Filing Date
US576413A Expired - Lifetime US2245301A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles
US576414A Expired - Lifetime US2082182A (en) 1931-11-20 1931-11-20 Manufacture of abrasive articles

Country Status (4)

Country Link
US (3) US2245301A (en)
DE (1) DE590459C (en)
FR (1) FR731457A (en)
GB (1) GB396385A (en)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2447374A (en) * 1934-04-25 1948-08-17 Granne Trust Company Method of applying coating materials
US2476145A (en) * 1944-08-12 1949-07-12 Libbey Owens Ford Glass Co Protection of surfaces
US2742018A (en) * 1952-01-02 1956-04-17 Lindquist Theodore Apparatus for coating by electrostatic force
US2976839A (en) * 1955-08-29 1961-03-28 D & S Proc Company Inc Apparatus for making pile fabrics
US2995393A (en) * 1957-10-30 1961-08-08 Nalco Chemical Co Method and apparatus for increasing the coefficient of friction between metal surfaces
US3122320A (en) * 1958-03-20 1964-02-25 Ford Motor Co Method for filling electrically charged receptacle
US3128773A (en) * 1961-03-15 1964-04-14 American Mach & Foundry Cigarette making machine
US3273016A (en) * 1964-04-23 1966-09-13 Oxy Dry Sprayer Corp Powder sprayers
US3292045A (en) * 1964-04-23 1966-12-13 Oxy Dry Sprayer Corp Electrostatic powder sprayer
US3292046A (en) * 1964-04-23 1966-12-13 Oxy Dry Sprayer Corp Powder sprayer with flexible blades
US3341740A (en) * 1966-08-15 1967-09-12 Oxy Dry Sprayer Corp Powder sprayer with flexible blades
US3344312A (en) * 1964-04-23 1967-09-26 Oxy Dry Sprayer Corp Electrostatic powder sprayer
US3468691A (en) * 1965-10-23 1969-09-23 Lipoma Electronics Co Method of and apparatus for the electrostatic application of solid particles to articles

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2742185A (en) * 1954-01-11 1956-04-17 Norton Co Method and apparatus for feeding and dispensing particulate materials
DE1080512B (en) * 1954-05-11 1960-04-28 Saladin & Co Method and device for producing plush, velvet, velor, artificial suede, emery cloth, sandpaper or the like by electrostatically driving in small particles
DE1163340B (en) * 1955-04-23 1964-02-20 Gerhard Ritzerfeld Lithographic printing form foil and process for their production
US2975757A (en) * 1958-02-26 1961-03-21 Gen Motors Corp Electrostatic paint spray
US2970929A (en) * 1958-03-12 1961-02-07 Norton Co Manufacture of coated abrasives
US3160524A (en) * 1962-02-13 1964-12-08 Xerox Corp Apparatus for charging powder particles and applying the charged particles to a receiving member
US3402658A (en) * 1965-01-06 1968-09-24 Owens Illinois Inc Electrical printing method which changes image size during powder transfer
US3457080A (en) * 1966-02-07 1969-07-22 Lipoma Electronics Co Method of and apparatus for the electrostatic application of solid particles to food products
NL135855C (en) * 1966-04-08
US3488411A (en) * 1966-04-20 1970-01-06 Alumacraft Marine Products Cor Production of low density thin gauge plastic articles
US3415222A (en) * 1967-03-20 1968-12-10 Indev Inc Electrostatic grid
US3900602A (en) * 1970-05-15 1975-08-19 Siemens Ag Method and device for the manufacture of catalytic layers for electrodes in electrochemical cells, particularly fuel cells
US3680779A (en) * 1970-10-05 1972-08-01 Oxy Dry Sprayer Corp Method and apparatus for electrostatic spraying
NL156300B (en) * 1972-12-27 1978-04-17 N Proizv Ob Agropribor DEVICE FOR EASILY BONDING OF GRAINY MATERIAL, IN PARTICULAR INSECT EGGS, ON A MOVING TAPE-SHAPED UNDERLAY.
US4138284A (en) * 1976-06-10 1979-02-06 Ppg Industries, Inc. Method of forming graded shade band on substrate
DK141376B (en) * 1976-06-21 1980-03-03 Weston Taeppefabrik As A method for continuously producing a fibrous web, and an apparatus for carrying out the method.
JPS5393396A (en) * 1977-01-28 1978-08-16 Yazaki Corp Abnormal sound preventive connector and method of producing same
DE2802020A1 (en) * 1978-01-18 1979-07-19 Artos Meier Windhorst Kg ARRANGEMENT FOR FIXING PRINTS WITH REACTIVE AND COUPLING DYES

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2447374A (en) * 1934-04-25 1948-08-17 Granne Trust Company Method of applying coating materials
US2476145A (en) * 1944-08-12 1949-07-12 Libbey Owens Ford Glass Co Protection of surfaces
US2742018A (en) * 1952-01-02 1956-04-17 Lindquist Theodore Apparatus for coating by electrostatic force
US2976839A (en) * 1955-08-29 1961-03-28 D & S Proc Company Inc Apparatus for making pile fabrics
US2995393A (en) * 1957-10-30 1961-08-08 Nalco Chemical Co Method and apparatus for increasing the coefficient of friction between metal surfaces
US3122320A (en) * 1958-03-20 1964-02-25 Ford Motor Co Method for filling electrically charged receptacle
US3128773A (en) * 1961-03-15 1964-04-14 American Mach & Foundry Cigarette making machine
US3273016A (en) * 1964-04-23 1966-09-13 Oxy Dry Sprayer Corp Powder sprayers
US3292045A (en) * 1964-04-23 1966-12-13 Oxy Dry Sprayer Corp Electrostatic powder sprayer
US3292046A (en) * 1964-04-23 1966-12-13 Oxy Dry Sprayer Corp Powder sprayer with flexible blades
US3344312A (en) * 1964-04-23 1967-09-26 Oxy Dry Sprayer Corp Electrostatic powder sprayer
US3468691A (en) * 1965-10-23 1969-09-23 Lipoma Electronics Co Method of and apparatus for the electrostatic application of solid particles to articles
US3341740A (en) * 1966-08-15 1967-09-12 Oxy Dry Sprayer Corp Powder sprayer with flexible blades

Also Published As

Publication number Publication date
GB396385A (en) 1933-08-01
US2245301A (en) 1941-06-10
US2082182A (en) 1937-06-01
DE590459C (en) 1934-01-03
FR731457A (en) 1932-09-03

Similar Documents

Publication Publication Date Title
US2027308A (en) Manufacture of abrasive articles
US2033991A (en) Coating apparatus
US2187624A (en) Apparatus for the manufacture of coated webs
US2194253A (en) Coating apparatus
US2466906A (en) Method and apparatus for forming fibrous webs
US2027307A (en) Method of coating and apparatus therefor and product
US1854071A (en) Method of manufacturing abrasives
US2318570A (en) Manufacture of abrasives
US2217444A (en) Method of and means for the manufacture of abrasive cloth
US3798048A (en) Method and apparatus for electrostatically coating an object
US2447664A (en) Electrostatic coating apparatus and method
US1788600A (en) Abrasive article and manufacture of same
US4088093A (en) Web coating and powder feed
USRE20660E (en) Method of coaxing and apparatus
US2254016A (en) Coating apparatus
US2184348A (en) Coating apparatus
US2027087A (en) Abrasive sheet and process of making the same
US2128907A (en) Method of making abrasive coated material
US4084019A (en) Electrostatic coating grid and method
USRE22419E (en) Method for making abrasive articles and apparatus therefor
US2300324A (en) Method of and mechanism for classifying finely comminuted material
US1110896A (en) Electrostatic separator.
US2457256A (en) Apparatus for manufacture of coated webs
US2636471A (en) Electrostatic coating apparatus
US2254531A (en) Coating apparatus