US3869896A

US3869896A - Rolling process

Info

Publication number: US3869896A
Application number: US425375A
Authority: US
Inventors: George P Carr; Jr James A Mason
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1972-06-26
Filing date: 1973-12-17
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

A rolling process for the fabrication of rolls in which a roll to be grooved is supported by a backing roll having a soft, resilient, abrasion-resistant outer layer having a range of hardness from about 40 Shore A to about 100 Shore D durometer.

Description

United States Patent Carr et a1. Mar. 11, 1975 1 ROLLING PROCESS {56] References Cited [75] Inventors: George P. Carr, Rochester; James UNITED STATES PATENTS A. Mason, Jr., Webster, both of 934,335 9/1909 Nahm et a1. 72/703 N.Y. 1,459,669 6/1923 Berold 1,487,591 3/1924 Na 101/7 [73] Asslgneei Xemx Cwporamn, Stamford, 2,114,072 4/1938 cle v eland 29/l48.4 (1099- 2,345,174 4/1944 Malnar 101/7 2,638,050 5/1953 King 29/1484 [22] 1973 2,695,857 11/1954 Lewis et a1 721010. 10 [2]] App], No; 425,375 3,150,707 9/1964 Howell 72/465 Related Application Data Primary ExaminerLowell A. Larson [63] Continuation-impart of Ser. No. 266,175, June 26,

1972, abandoned. 57 ABSTRACT A rolling process for the fabrication of rolls in which a 72/108 f J g Z roll to be grooved is supp rted by a backing r011 having a soft resilient, abrasiomresistam outer layer [58] Field of Search 101/6, 7, 375, 401.1, g a range of hardness from about 40 shore A to 72/102, 108, 109, 465, 703, DIG. 14; 29/148.4 D, 132; 156/14; 10/107 F about 100 Shore D durometer.

19 Claims, 1 Drawing Figure ROLLING PROCESS This application is a continuation-in-part of application Ser. No. 266,175 filed June 26, l972, now abandoned.

This invention relates to a rolling process for fabricating grooved rolls.

It is well known that in various metal working operations employing rolls, it is necessary to provide backing rolls. The use of such backing rolls is perhaps best understood with reference to the metal industry where they are used generally in combination with work rolls to counteract detrimental effects the work rolls. Thus, in the case of various roll fabrication techniques, it is desirable to provide backing rolls so that the proper application of force to work rolls will be provided. The concepts of this invention will be described hereinafter with respect to metal working; however, it will be understood that these concepts are applicable to other materials. Thus, the major considerations involved herein concern the use of backing rolls in combination with impression rolls which in turn engage work rolls passing relative thereto.

ln electrostatic recording as typified by xerography, it is usual to form an electrostatic latent image on an insulating or photoconductive insulating surface, generally conforming to information to be recorded or reproduced. This image may then be developed or made visible by the application of an electrostatically attractable material which deposits in conformity with the electrostatic latent image to produce a visible record In the usual embodiments of electrostatographic development it is conventional to employ finely divided insulating materials, generally powders, which are presented to the image bearing surface in particulate form. Thus, conventionally, the electrostatic latent image is generally beads or granules bearing on their surfaces finely divided pigmented toner particles. Alternatively, insulating or conductive toner or liquid ink have been presented to the image in an air suspension. Likewise, toner may be carried on the surface ofa brush or brushlike fiber such as a fur brush or a simulated brush of magnetically adhering particles.

As disclosed in U.S. Pat. No. 3,084,043, to Robert Gundlach, an electrostatic latent image may be devel oped or made visible by presenting to the image surface a liquid or ink developer on the surface ofa suitable developer dispensing member. Such developer dispensing member comprises a support base having disposed on its surface a raised pattern which may comprise a plurality of fine raised lines, dots, or other raised material. The patterned material on the developer dispensing surface is generally a very finely divided pattern, regular in configuration or at least in pattern size, and adapted to maintain spacing between a developer dispensing surface and a developer receiving surface sufficient to keep the developer out of contact with the recording surface in the background areas. The developer dispensing member is prepared for use by an inking process in which ink is supplied to fill the valleys between the islands or dots ofthe pattern. This may be accomplished, for example, by wiping the surface with a thoroughly inked cloth or by means of inking rolls or the like, preferably followed by squeegeeing off the ex cess ink. When prepared in this manner, the developing dispensing member bears on its surface substantially uniform film of developer punctured by the dots or other raised pattern in such a manner that a smooth surface pressed in contact with the developer dispensing member is in contact only with the noninked peaks of the pattern and not with the developer film. Desirably, sufficient ink should be placed on and allowed to remain on the surface of the developer dispensing member so that this member may be placed against a sheet of paper or other relatively smooth surface without transferring quantities of developer to such surface. For image development, the surface of the developer dispensing member is pressed either simultaneously or progressively into the image bearing surface causing developer transfer to the image surface in conformity with the electrostatic image.

The working surface ofa roll for application of a liquid developer to an electrically charged photoreceptive surface is composed, for example, of a multihelicoid thread pattern having from about 150 to about 300 threads per inch at about 45 right or left hand lead. Other angles may be used such as 20 to from axis. The thread configuration is typically about 00055 inch pitch, about 0.001 inch top land, and with about 35 to 65 micron depth. The overall roll size may be typically about 1.5 inch in diameter and approximately 9 inches in length, exclusive of journals. Such a roll may be made from aluminum or alloy, or low carbon steel and chromium plated for corrosion and wear protection and is generally fabricated by mechanical engraving. However, as is obvious to those skilled in the art of mechanically engraving such rolls, it is apparent that such a method of fabrication is very time consuming and inherently leads to high costs of manufacture. Using a trihelicoid pattern as an example, the following would be the basic steps to produce a mechanically engraved roll:

I. A master layout of the pattern, opposite hand, many times size, is made on a polyethylene terephthalate resin material.

2. The master layout is photographically reduced to the proper size, again on a clear polyethylene tercphthalate resin material.

3. The master pattern is transferred to a hardened and ground tool steel master engraving cylinder by a photoetching process. Only the pattern outline is transferred, not the pattern depth. W

4. The photo-etched master engraving cylinder is me chanically etched by a master engraving to the desired depth and contour. This step is critical and requires great skill. The tools and equipment used are relatively simple and very similar to a jewelers etching equipment. Subsequent engraving success depends almost entirely on the skill of the master engraver.

5. The master cylinder is then used to make master mills for the engraving of rolls. The process used for making the master mills is basically the same as used for engraving rolls and is explained subsequently in Step 7.

6. A roll blank is machined to tolerance by conventional means. An extension is left on one end and this is used to drive the roll during the mechanical engraving process. After engraving, the extension is machined off. The roll material is usually AlSl l0l5 or I020 steel.

7. The roll is now ready for engraving. During the engraving process, the roll is placed in a special lathe designed for this purpose. The roll is placed in the machine with the roll journals supported by bronze U" shaped bearings. The extension that is left on the roll is engaged in a floating chuck that drives the roll during the engraving process. The master engraving mill is mounted in a tool holder directly above the roll. The tool holder rests on the lathe bed and is driven back and forth by a lead screw. The master mill freely floats in the U-shaped bronze bushings in the tool holder and not driven. By means of an adjusting wheel, it is brought in contact with the rotating blank roll, picks up the speed of the blank roll and is driven by frictional contact. The advance along the blank roll is controlled by the lead screw driving the tool holder. The blank roll rotates very slowly, usually no more than rpm. The advance of the master mill along the length of the blank roll is also very slow, approximately 1 inch over 3 minutes for small rolls and considerably slower for larger rolls. On larger rolls it is nearly impossible to see the mill advance down the roll as it is moving so slowly. The master mill is rarely bottomed in a single pass. Usually at least two passes are required on every roll and sometimes considerably more. The amount of infeed per pass is at the discretion of the operator. During engraving, the roll is continuously flooded with lubricant.

8. After engraving, the journal extension is machined off, and the roll is degreased and and given a flash coating of copper.

9. The final step consists of plating with a thin coat of hard chromium. Both plating operations require considerable skill and the usual plating setup normally would not plate completely and uniformly into such intricate configurations.

Other roll manufacturing processes have one or more dificiencies. For example, milti-die thread cutting has some feasibility for producing a multihelicoid pattern, however, it is very difficult to obtain about a 45 lead angle with this process, the maximum lead angle obtainable usually being about 25from the normal to the axis. In producing a multihelicoid pattern on an applicator roll, usually a minimum of 150 threads per inch are desirable and about 180 threads per inch are preferred. With multi-die thread cutting, it is difficult to produce a die of about 180 threads per inch. Further, a special chucking machine that can feed small rolls at about 0.5 inch per revolution is required for a small roll such as one about one inch in diameter and about 9 inches in length. However, even this rate of feed is quite slow and compounded with the considerable amount of set up time required, this process provides low rates of productivity. Photo engraving/chemical etching also has some feasibility for producing patterned rolls except for one major drawback. That is, it is very difficult to line up and join the ends of the overlay to produce a continuous pattern. A further limitation is that the maximum etched depth obtainable is usually about 25j microns. Cylindrical panographic engraving equipment can produce a mutlihelicoid pattern, but again the alignment of the thread pattern is a problem the same as occurs in the photoengraving process. An electronic automatic cylinder engraving machine may produce about a 180 TPI at about a 45 lead angle multihelicoid pattern, or other patterns, on a continuous cylindrical surface. However, since it is a true engraving process, it is slow and thus costly. Electrochemical grinding is also unsatisfactory for fabricating a roll having about 180 TPI because the finest grinding wheel has an individual particle size nearly as large as the largest thread feature.

Conventional rolling as a method of fabricating rolls differs from knurling primarily in that in rolling, the roll to be grooved is supported by a backing roll instead of on-end bearings. This allows centerless supports to be used and makes it possible to increase the rate of productivity. An impression tool is pressed against the work roll and allowed to track along the length of the roll to be grooved. The backing roll is conventionally hard steel which compresses and distorts the newly formed grooves and consequently produces unacceptable rolls, especially when fine patterns such as about TPI or greater are to be formed. The use of a reverse threaded impression tool avoids the distortion mentioned above, but produces an unsatisfactory double knurl or diamond pattern which is undesirable for some applications because it develops excessively broken line patterns. Further, if soft metal backing rolls such as copper, brass, aluminum or the like are employed, these backing rolls lack durability and wearing qualities which rapidly lead to distortion resulting in nonuniform dimensions in both the backing roll and the roll being fabricated. It is also highly desirable to employ a backing roll which is chemically and mechanically stable and capable of retaining concentricity during use without being susceptible to the adverse effects of heat, humidity, solvents and abrasion. Obviously, a backing roll susceptible to thermal expansion is undesirable because it may lead to variations in dimensional structure of the roll being fabricated. Also, a metal backing roll susceptible to oxidation effects is undesirable since rusting may occur and result in rust particle removal from the backing roll and cause damage by falling and embedding in the fabricated rolls. In addition, Coolants and lubricating fluids containing solvents are conventionally employed in roll fabricating processes which further limit the materials that may be employed as backing rolls due to obvious complications such as chemical instability of both the backing roll and the fabricated roll.

Since most roll manufacturing processes are deficient in one or more of the above areas, there is a continuing need for an improved method of fabrication rolls.

, SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide a roll manufacturing process overcoming the above noted deficiencies.

It is another object of this invention to provide a roll manufacturing process which provides dimensional stability to rolls during fabrication.

It is another object of this invention to provide a roll manufacturing process which minimizes damage to fabricated rolls.

It is a further object of this invention to provide a roll manufacturing process which is capable of retaining fabricated roll and backing roll concentricity during use.

Another object of this invention is to provide a roll manufacturing process employing a backing roll which is more durable to the action of fabricated rolls pressed thereagainst.

It is a further object ofthis invention to provide a roll manufacturing process employing a backing roll which is more resilient, wear resistant, and of comparatively low hardness.

it is a further object of this invention to provide a roll manufacturing process which is greatly simplified when compared with previously known processes.

It is another object of this invention to provide a roll manufacturing process which is significantly less time consuming and costly than conventional processes.

It is another object of this invention to provide a roll manufacturing process which enables higher degree lead angles to be obtained in fabricated rolls.

It is another object of this invention to provide a roll manufacturing process which enables the fabrication of continuous pattern in work rolls.

It is another object of this invention to provide a roll manufacturing process which is superior to known roll manufacturing processes.

The above objects and others are accomplished, generally speaking, by providing a rolling process for fabricating patterns in cylindrical rolls comprising providing a smooth surfaced cylindrical work roll, impressing a pattern into the cylindrical work roll with an impression device while the work roll is rotated about its axis and supported by a soft, resilient, abrasion resistant, rotating cylindrical backing roll.

In accordance with this invention, any suitable conventional thread rolling machine may be employed in the roll manufacturing process of this invention. In the practice of this invention there are employed three major innovations over the conventional thread rolling machine operation. The first innovation is that one of the machine dies that is, the conventional backing roll, is replaced with a soft, pliable, resilient elastomer or elastomeric-like backing roll. Secondly, the backing roll drive is disengaged during the rolling cycle and the backing roll is allowed to roll freely so as to pick up the speed of the part being rolled by rolling in contact with it. Since the dies are generally independently driven, this obviates the need for perfect synchronization of driving speeds. Ordinarily, even the slightest variation in die speeds would cause tearing of the threads on a fine pitch such as about 180 TF1. The third innovation is that the die having an impression tool mounted thereon and the backing roll are brought into place to engage and fully grip the work roll before rolling starts instead of being in motion and at full speed with the work fed into them, as is the usual case. The relative position of the backing roll to the work roll is usually so that the axis of the backing roll and that of the work roll are in line with each other and both may be in a horizontal plane or a vertical plane. One backing roll is usually employed with a conventional thread rolling machine. however, as is obvious, more than one backing roll may be employed if so desired with different machine designs and such use is intended to be within the scope of this invention.

One ofthe several configurations possible employing the concepts of this invention are shown in the drawing. The FIGURE represents an end view of a roll process fabrication device where a substantially smooth surfaced cylindrical work roll 1 is supported by a soft, resilient, abrasion resistent, freely rotatable substantially cylindrical backing roll 3. Work roll 1 is contacted with a die 2 which is driven by a power mechanism (not shown) so that the work roll 1 is engaged and impressed with the die pattern while supported by the resilient backing roll 3.

The backing rolls employed in the process of this invention comprise a surface layer of an elastomeric-like or other resilient composition adhering to a coated or uncoated metal core. Any composition may be employed as the surface layer for the backing rolls in the roll manufacturing process of this invention, if the surface layer is softer than the working roll. Satisfactory compositions are those which are relatively incompressible at the molding temperatures and pressures having a working surface defromable to the shape and texture of the article to be fabricated. Suitable compositions include those having a range of hardness from about 40 Shore A to about I00 Shore D durometer. Typical compositions include polyacrylates, polyisobutylenes. polyurethane, polyamides such as, for example. mylon 66, nylon 6, nylon 610, nylon 4, nylon l0, nylon ll. nylon l2, and others, fluoroelastomers, chlorosulfonated polyethylene, polyethylene, block copolymers of styrene and poly (dimethyl siloxane), natural rubber, polytetrafluoroethylene, polychloroprene, nitrile, polybutadiene, polyisoprene, polysulfide. styrene butadiene, epichlorohydrin silicone, random copolymers of polyethylene and polypropylene with hexadiene, and mixtures thereof.

Substantially incompressible compositions suitable for the manufacture of the backing rolls employed in the roll manufacturing process of this invention may consist of a mixture of diisocyanates and polyethers or polyesters which are mixed together and reacted under controlled conditions. This process forms the prepolymer which is then reacted with a curing agent. The liquid material is then case directly into molds or is processed further for compression, transfer, or injection molding. These materials possess the combined properties of elasticity, stiffness, tear and abrasion resistance suitable for the practice of this invention. Either the polyisocyanate, polyester or polyether should have an average number of reactive groups sufficient to provide a moderate degree of branching. For example, we may use a mixture of a moderately branched polyester having about two isocyanate reactive terminal groups and a diisocyanate. Polyesters having more branching such as those averaging about four hydroxyls per molecule require a higher proportion of isocyanate to achieve the desired hardness in the backing rolls. in all cases, the higher the proportion of diisocyanate that is employed, usually the harder is the cured roll. Conversely, isocyanate to hydroxyl ratios below about one are not often used since they generally lead to rolls of undue softness. in accordance with practice known to those skilled in the art, the polyesters which we may use in our invention are dry and free of strong acids which may induce aging of the backing rolls. The diisocyanates which may be employed in the reaction with the polyester are those which melt above about 150 C. when the diisocyanate is to be added to polyester or polyester-isocyanate to give the final casting composition. Compositions having a hardness of from about to about Shore D durometer, a tensile psi in the range of about 4,000 to about 7,000, an abrasion loss (mm in the range of about 25 to about 55, a tear die C PL] in the range of about 300 to about 1,200, a tear nicked PL] in the range of about to about 1,000, a rebound resilience in the range of about 20 percent to about 45 percent, a specific gravity in the range of about 1.1 to about 1.3, elongation in the range of about 250 percent to about l,1l0 per-cent, elongation set in the reange of about 2 percent to about 25 percent, 300 percent modulus PSl in the range of about 400 to about 4,000, 100 percent modulus PS1 in the range of about 200 to about 5,000, and compression set B percent in the range of about 10 to about 40 are preferred because they provide the use of harder and better wearing materials in the backing roll without destroying its resilienc When the surface layer of the backing roll is a polyurethane, the polyurethane may be formed by reaction ofa polyethylene glycol, or other polyol, and an isocyanate compound. A polyethylene glycol suitable for use in this invention may in general be any of those commercially available with the selection of a particular material being dependent upon the intended use of the backing roll. In general, such compounds are formed by reacting the ethylene oxide with water, ethylene glycol, or diethylene glycol, and have the general structure configuration: HOCH CH O(CH CHO-),CH CH OH.

Any suitable isocyanate compound may be employed in preparing the polyurethanes employed in the backing rolls of this invention. Typical isocyanate compounds include 3,3'-bitolylene-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3- dimethyldiphenylmethane-4,4'-diisocyanate, metaphenylene diisocyanate, 2,4, tolylene diisocyanate dimer, triphenylmethane triisocyanate, hexamethylene diisocyante, dianisidine diisocyanate, polyaryl triisocyanate, and the like.

Any suitable polyol may be employed in preparing the polyurethanes employed in the backing rolls of this invention. Typical polyols include trimethylolpropane, 1,4 butanediol, 1,2,6 hexanetriol, sorbitol, amino alcohol, N,N,N,N-tetrakis(2-hydroxyl propyl) ethylene diamine. dior polyfunctional silanols based on polydimethyl siloxane and the like.

Any suitable polyamide such as nylon or nylonrelated materials may likewise be used in the backing rolls of this invention.

Any suitable thickness for the outer surface layer of the backing roll may be employed in the process of this invention. Preferred thickness include about one to about three inches of outer surface layer on about a three inch steel core. However, it is quite apparent that the thickness of the outer surface layer of the backing roll may vary according to the particular conditions to be encountered in use, and to some extent, by the size of the roll. Thus, the thickness of the outer surface layer of the backing roll should be sufficient as to prevent possible damage to the threads, patterns or profile of work rolls when the work roll is pressed into the backing roll by the impression tool during fabrication.

Any suitable length for the backing roll may be employed in the process of this invention. Typical lengths include from about one inch to about twelve inches. However, when fabricating a grooved aluminum roll of about one inch in diameter and about twelve inches in length, satisfactory results are obtained with a backing roll of about two inches in length.

Any suitable malleable material may be rolled by the process of our invention. Typical malleable materials include aluminum alloys, low carbon steels, carbon and alloysoft leaded steel, soft stainless steels, brass, copper, and copper base alloys. In general, any material that may be knurled may be rolled by the process of this invention.

Any suitable impression tool may be employed in the process of this invention. Typical impression tools include knurling rolls and the like which may be employed to make threads, patterns, profiles, or imprint numbers on work rolls. However, in the fabrication of rolls to be employed for application of a liquid developer to an electristatically charged photoreceptive surface, an impression tool having a trihelicoid thread pattern of about 180 threads per inch at about a right or left hand lead, a thread configuration of about 0.0055 inch pitch, about 0.001 inch top land, and about a 35 to about 65 micron depth is preferred because maximum results are obtained in electrostatographic development.

Any suitable pressure may be applied to the backing rolls employed in the process of this invention. Typical pressures include about 11,000 to about 15,000 PS1. However, as is apparent, the pressure employed is dependent to some extent upon the hardness of the work roll and the parituclar pattern or profile to be obtained in the fabricated work roll.

Any suitable fabricated workroll wherein threads knurls, patterns, and the like are desired may be rolled by the process of this invention. Typical fabricated work rolls include shafts, studs, bolts, pipes, fittings. castings with studs and the like.

In general, the quality of the roll fabricated is dependent on the pressure exerted and the temperature of the backing roll. There may be considerable heat generated in the rolling process which in turn may heat up the backing roll to change its physical properties. Until the backing roll reaches static conditions, it may be desirable to adjust the rolling pressure periodically to compensate for these changes and still make the same quality workpiece. lt has been found that sufficient quality control can be maintained over the rolling process by observing the rolled parts periodically under a simple microscope. The main points to be observed are the thread form and the lack of defects such as tear and burnishing. Periodic examination is desirable to insure that metal chips have not become imbedded in the die or in the backing roll as this may result in damaged workpieces. Thread depth may be controlled by the use of a gravure type microscope which measures thread depth directly where thread depth is critical.

It has been found that the process of this invention satisfactorily duplicates the surface produced by mechanical engraving. The production time required for producing a satisfactory rolled surface according to the process of this invention is about fifteen seconds compared with about forty-five minutes by mechanical engraving, exclusive of loading and handling time in each case. Fabricated rolls produced according to the process of this invention may have a greater thread depth than mechanically engraved rolls, for example, about microns compared with about 35 microns respectively. This greater thread depth may be the reason why in some instances the rolled rolls fabricated according to the process of this invention provide developed electrostatic latent images with less background. Also, this greater thread depth is of interest in imaging and coating applications where a greater liquid developer or coating material holding capacity is desirable. Thus, the process of this invention is also appropriate for the fabrication of coating rollers as well as gravure printing cylinders. In addition, the process of this invention is inherently applicable to the production of regularly spiraled quadragravure or pyrimidal dot patterns.

addition, workpieces such as rolls with a unidirectional helicoid or multihelicoid groove pattern may be fabricated by the rolling process of this invention. Further, the backing roll design prevents damage to the workpieces being fabricated as they are pressed against the backing roll by the impression tool. The backing rolls of this invention are designed whereby the backing roll distributes the work load and counteracts the forces from the impression roll in such a manner as to prevent deformation of the profile imposed into the work roll by the impression roll. The backing roll prevents deformation of the profile of the fabricated work roll while fulfilling the basic function of controlling deflection.

DESCRIPTION OF PREFERRED EMBODIMENTS The following examples further define, describe and compare method of utilizing the process of this invention of fabricate rolls.

EXAMPLE I A blank roll of 2024-T4 aluminum alloy about one inch in diameter and about nine inches long with the diameter held within a total tolerance of about 0.0055 inch is inserted in a machine such as available from Reed Rolled Thread Die Company, Worcester, Mass, Model 8-1 12. The machine is a directly opposing two die straight through or on center thread rolling machine with a capacity of part size from about Vs inch to about 2 /2 inches in diameter and up to about 24 inches in length when supported on centers, and up to about feed in length on thru feed. One of the machine dies is removed and replaced with a polyruethane backing roll (the polyurethane is commercially known as Disogrin, available from Disogrin Industries, Division of Pellon Corporation, Manchester, NH.) which is about 3.5 inches in diameter and about 1.5 inches in length. The polyurethane backing roll has a hardness of about 80 Shore A durometer and is mounted on a spindle. The polyurethane backing roll drive is disengaged. A knurling die about 3.5 inches in diameter and about 1.0 inch in length made of hard steel to produce about a 45 lead angle helix patterned roll containing about 180 threads per inch is mounted on a spindle on the other machine head. The aluminum blank work roll is mounted on centers in the machine and held by hydraulic pressure. The knurling die and the polyurethane backing roll are brought into place to engage and fully grip the aluminum blank work roll at a pressure of about l5,000 pounds per square inch before rolling is started. The machines centers are free floating, within limits, in a centering device so that the work roll is always centered between the knurling die and the backing roll during the rolling process. The machine is started at a die speed of about I50 rpm and as the knurling die rotates it pulls the blank roll forward in the centering device. When the knurling die and backing roll initially engage the blank roll and the thread .rolling starts there is some slippage until enough thread form has been generated to pull the centering device forward. With very fine and shallow thread rolling, there is insufficient strength in the few initial threads to overcome the resistance of the blank roll holder and these threads tear. This results in about A inch of thread tear on the lead-in end ofthe blank roll. For this reason, the journals are not machined until after the part has been rolled. As the threads are rolled in the blank roll they become the gripping surface pulling the part forward. When the part is completely rolled, the machine stops and the knurling die and the backing roll retract. The centering device pressure is released and the fabricated part is removed from the machine. About thirteen seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 60 microns.

To determine the quality of the roll fabricated, the grooved surface is cleaned with a solvent to remove any contaminent such as grease and oil. The roll is mounted in a machine suitable for electrostatographic polar liquid development and positioned in contact with a photoreceptor surface. The photoreceptor is a photosensitive paper composed of an electroconductive paper substrate and a photoconductive layer thereover of powdered zinc oxide in an insulating resinous binder. The photoreceptor surface is electrostatically charged uniformly by means of corona discharge and subjected to imagewise exposure of a light and shadow pattern to form an electrostatic latent image thereon. The latent image is developed with a polar, conductive homogeneous liquid contained in a trough which is applied to the roll by a feed roller. Excess liquid from the roll surface is carefully wiped away at every cycle by a doctoring device. The clean tips of the ridges on the roll provide a finite spacing between the photoconductor and the liquid. The liquid is retained in the grooves of the roll and out of mechanical contact with the photoconductor surface. Development by electrostatic attraction takes place on the photoconductor surface in those areas of the photoconductor containing an electrical charge by the liquid creeping up the sides of the roll cell walls into contact with the photoconductor. In those areas of the photoconductor which are not electrostatically charged, the liquid remains in the roll cell walls out of contact with the photoreceptor. The printing speed is about 10 inches per second. The printed copy produced by the rolled aluminum roll is in general equal to and in some cases superior to that produced by a mechanically engraved low carbon steel roll which has been chromium plated having substantially the same pattern as the rolled roll and employed as a control in that less background is obtained.

EXAMPLE II A blank roll of 2024-T4 aluminum alloy about one inch in diameter and about nine inches in length with the diameter held within a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example 1. One of the machine dies is removed and replaced with a polyisoprene backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polyisoprene backing roll has a hardness of about 50 Shore A durometer and is mounted on a spindle. The polyisoprene backing roll drive is disengaged. A knurling die as described in Example I is mounted in the machine as in Example I. The aluminum blank roll is mounted in the machine as in Example I. The rolling process of Example I is followed. About thirteen seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 60 microns.

Copy quality evaluation of the grooved roll is done as in Example I. The printed copy produced by the rolled aluminum roll is in general equal to and in some cases superior to that produced by a mechanically engraved roll as described in Example I and employed as a control in that less background is obtained.

EXAMPLE Ill A blank roll of 606l-TG aluminum alloy about one inch in diameter and about nine inches long with the diameter held within a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example I. One of the machine dies is removed and replaced with a polyurethane backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polyurethane backing roll has a hardness of about 80 Shore A durometer and is mounted on a spindle. The polyurethane backing roll drive is disengaged. A knurling die as described in Example I is mounted in the machine as in Example I. The aluminum blank roll is mounted in the machine as in Example I. The rolling process of Example I is followed. About thirteen seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 55 microns.

EXAMPLE lV A blank roll of 606l-TG aluminum alloy about one inch in diameter and about nine inches long with the diameter held within a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example I. One of the machine dies is removed and replaced with a polyisoprene backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polyisoprene backing roll has a hardness of about 50 Shore A durometer and is mounted on a spindle. The' poly-isoprene backing roll drive is disengaged. A knurling die as described in Example I is mounted in the machine as in Example I. The aluminum blank roll is mounted in the machine as in Example I. The rolling process of Example I is followed. About thirteen sec- EXAM PLE V A blank roll of 2024-T4 aluminum alloy about one inch in diameter and about nine inches long with the diameter held within a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example 1. One of the machine dies is removed and replaced with a polyurethane backing roll which is about 3.5

inches in diameter and about 1.5 inches in length. The polyurethane backing roll has a hardness of about Shore D durometer and is mounted on a spindle. The polyurethane backing roll drive is disengaged. A knurling die as described in Example I is mounted in the machine as in Example I. The aluminum blank roll is mounted in the machine as in Example I. The rolling process of Example I is followed. About thirteen seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 60 microns.

EXAMPLE VI A blank roll of 606l-TG aluminum alloy about one inch in diameter and about nine inches long with the diameter held with a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example I. One of the machine dies is removed and replaced with a polyurethane backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polyurethane backing roll has a hardness of about Shore D durometer and is mounted on a spindle. The polyurethane backing roll drive is disengaged. A knurling die as described in Example] I is mounted in the machine as in Example I. The aluminum blank roll is mounted in the machine as in Example I. The rolling process of Example I is followed. About 13 seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 60 microns.

EXAMPLE Vll A blank roll of mild steel about one inch in diameter and about nine inches long with the diameter held within a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example I. One of the machine dies is removed and replaced with a polyurethane backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polyurethane backing roll has a hardness of about Shore D durometer and is mounted on a spindle. The polyurethane backing roll drive is disengaged. A knurling die as described in Example l is mounted in the machine as in Example I. The mild steel blank roll is mounted in the machine as in Example I. The rolling process of Example l is followed. About fifteen seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 55 microns.

Copy quality evaluation of the grooved roll is done as I in Example I. The printed copy produced by the rolled mild steel roll is in general equal to and in some cases superior to that produced by a mechanically engraved roll as described in Example I and employed as a control in that less background is obtained.

EXAMPLE VIII A blank roll of mold steel about one inch in diameter and about nine inches long with the. diameter held within a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example I. One of the machine dies is removed and replaced with a polyisoprene backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polyisoprene backing roll has a hardness of about 40 Shore A durometer and is mounted on a spindle. The polyisoprene backing roll drive is disengaged. A knurling die as described in Example I is mounted in the machine as in Example I. The mild steel blank roll is mounted in the machine as in Example I. The rolling process of Example I is followed. About 15 seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 55 microns.

Copy quality evaluation of the grooved roll is done as in Example I. The printed copy produced by the rolled mild steel roll is in general equal to and in some cases superior to that produced by a mechanically engraved roll as described in Example I and employed as a control in that less background is obtained.

EXAMPLE IX A blank roll of copper about 1 inch in diameter and about nine inches'long with the diameter held within a total tolerance of about 0.0005 inch is inserted in the machine disclosed as in Example I. One of the machine dies is removed and replaced with a polybutadiene backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polybutadiene backing roll has a hardness of about 70 Shore Ddurometer and is mounted on a spindle. The polybutadiene backing roll drive is disengaged. A knurling die as described in Example I is mounted in the machine as in Example I. The copper blank roll is mounted in the machine as in Example I. The rolling process of Exampel I is followed. About thirteen seconds are required to groove the blank roll from the time the machine is started. The average thread depth of the grooved roll is about 60 microns.

Copy quality evaluation of the grooved roll is done as in Example I. The printed copy produced by the rolled copper roll is in general equal to and in some cases superior to that produced by a mechanically engraved roll as described in Example I and employed as a control in that less background is obtained.

EXAMPLE X A blank roll of copper about one inch in diameter and about nine inches long with the diameter held within a total tolerance of about 0.0005 inch in inserted in the machine disclosed as in Example I. One of the machine dies is removed and replaced with a polyurethane backing roll which is about 3.5 inches in diameter and about 1.5 inches in length. The polyurethane backing roll has a hardness ofabout 80 Shore A durometer and is mounted on a spindle. The polyurethane backing roll drive is disengaged. A knurling die as described in Example I is mounted in the machine as in Example I. The copper blank roll is mounted in the machine as in Example I. The rolling process of Example l is followed. About 13 seconds are required to groove the blank roll from the time the machine is started. The

average thread depth of the grooved roll is about 60 microns.

Although specific materials and conditions are set forth in the foregoing examples, these are merely intended as illustrations of the present invention. Various other suitable roll materials such as those listed above may be substituted for those in the examples with similar results. Other materials may also be added to the backing roll materials to sensitize, synergize or otherwise improve the fabricating properties or desirable properties of the process. Any system which imparts stresses to work rolls which may be counteracted by the backing rolls employed in the process of this invention is contemplated by this disclosure.

Other modifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure. These are intended to be included within the scope of this invention.

What is claimed is:

1. A rolling process for fabricating patterns in cylindrical rolls comprising providing a substantially smooth surfaced cylindrical work roll, impressing a pattern into said cylindrical work roll with an impression device while said cylindrical work roll is rotated about its axis and supported by a soft, resilient, abrasion resistant. freely rotatably substantially cylindrical backing roll.

2. A rolling process according to claim 1 wherein said cylindrical work roll is rotated about its axis and supported by said cylindrical backing roll mounted on a thread rolling machine having at least two independently driven dies.

3. A rolling process according to claim 2 including replacing one of said dies with said cylindrical backing rolls.

4. A rolling process according to claim 3 including disengaging the drive of said cylindrical backing roll.

5. A rolling process according to claim 4 including bringing said cylindrical backing roll and said impression device into contact with said cylindrical work roll before rolling starts.

6. A rolling process according to claim 1 wherein said cylindrical backing roll comprises a surface layer of a soft, resilient, abrasion resistant composition adhering to a metal core.

7. A rolling process according to claim 6 wherein said composition has a hardness from about 40 Shore A to about 100 Shore D durometer.

8. A rolling process according to claim 6 wherein said composition has a hardness from about to about Shore D durometer.

9. A rolling process according to claim 6 wherein said composition is selected from the group consisting of polyurethane polyisoprene, polybutadiene and nylon.

10. A rolling process according to claim 6 wherein said cylindrical backing roll comprises from about one to about three inches of said surface layer of said composition adhering to said metal core.

11. A rolling process according to claim 1 wherein said impression device comprises a trihelicoid thread pattern from about to about 240 threads per inch at about a 45 lead, a thread configuration of about 0.005 inch pitch, about 0.001 inch top land, and about a 35 to about 65 micron depth.

12. A rolling process according to claim 1 including impressing said pattern into said cylindrical work roll with said impression device at a pressure of from about 11,000 to about l5,000 pounds per square inch while said cylindrical work roll is rotated about its axis and supported by said rotating cylindrical backing roll.

13. A rolling process according to claim 12 wherein said cylindrical backing roll counteracts said pressure to prevent deformation of said pattern impressed into said cylindrical work roll with said impression device.

14. A rolling process according to claim 1 wherein said cylindrical work roll is about one inch in diameter and about nien inches in length.

15. A rolling process according to claim 14 wherein said cylindrical work roll comprises an aluminum roll.

16. A rolling process according to claim 14 wherein said cylindrical work roll comprises a copper roll.

17. A rolling process according to claim 14 wherein said cylindrical work roll comprises a mild steel roll.

18. A rolling process according to claim 1 including impressing said pattern into said cylindrical work roll with said impression device at a speed ofabout revolutions per minute while said cylindrical work roll is rotated about its axis and supported by said cylindrical backing roll.

19. A rolling process according to claim 1 including impressing said pattern into said cylindrical work roll with said impression device in about thirteen seconds while said cylindrical work roll is rotated about its axis and supported by said cylindrical backing roll.

Claims

1. A rolling process for fabricating patterns in cylindrical rolls comprising providing a substantially smooth surfaced cylindrical work roll, impressing a pattern into said cylindrical work roll with an impression device while said cylindrical work roll is rotated about its axis and supported by a soft, resilient, abrasion resistant, freely rotatably substantially cylindrical backing roll.

8. A rolling process according to claim 6 wherein said composition has a hardness from about 70 to about 95 Shore D durometer.

11. A rolling process according to claim 1 wherein said impression device comprises a trihelicoid thread pattern from about 180 to about 240 threads per inch at about a 45* lead, a thread configuration of about 0.005 inch pitch, about 0.001 inch top land, and about a 35 to about 65 micron depth.

12. A rolling process according to claim 1 including impressing said pattern into said cylindrical work roll with said impression device at a pressure of from about 11,000 to about 15,000 pounds per square inch while said cylindrical work roll is rotated about its axis and supported by said rotating cylindrical backing roll.

18. A rolling process according to claim 1 including impressing said pattern into said cylindrical work roll with said impression device at a speed of about 150 revolutions per minute while said cylindrical work roll is rotated about its axis and supported by said cylindrical backing roll.