US3162040A - Methods and devices for examining the flatiness or the exactly concentric cylinder-shape of a plane or cylindric surface, e. g. the active surface of printing-forms and/or of the supporting member thereof - Google Patents

Description

Dec. 22, 1964 M. CAHEN 3,162,040

METHODS AND DEVICES FOR EXAMINING THE FLATNESS OR THE EXACTLY coNcENTRIc CYLINDER-SHAPE OF A PLANE 0R CYLINDRIC SURFACE, E.G. THE ACTIVE SURFACE OF PRINTING-FORMS AND/0R OF THE SUPPORTING MEMBER THEREOF Filed May 24, 1961 INVENIOR BY I 254 ATTORNEY United States Patent 3,162 640 METHODS AND DEVIQES FOR EXAMKNING THE FLATNESS OR THE EXACTLY CGNQENTREE C lldDhlt-SfiAPE UF A PLANE GR (IYLENDRIC SURFACE, E.G. THE AQTWE SURFAIJE 0F PRiNTlNG-FGRMS AND/0R THE dUPPGRT- ENG NEE BEER TIEREGF Max Cahen, iapierstraat 6-8, s-Hertogenhesch, Netherlands Filed May 24, B61, Ser. No. 112,427 Claims priority, application Netherlands May 28, 1969 9 Claims. (iii. TS-Hi4) The invention relates to a method and an apparatus examining the flatness or the exactly concentric cylindershape of a plane or cylindric surface, e.g. the active surface of a flat or cylindric supporting member and/ or a layer or plate provided on such a supporting member, such as a layer or plate provided with printing-forms, by means of a colouring-matter, which is applied in a thin film by means of a roller on the surface to be tested.

In the printing-technique several methods and devices for the above meant examination are used. For instance it has already been proposed to use a micro-meter adapted to be moved over a surface plate or along a descriptive line of a cylinder, by means of which micro-meter a topographical diagram of the height variations of the active surface of the printing-form was made by scanning the latter point by point. This work takes up much time, and has moreover an unsatisfactory result, if the printingblocks or printing-forms are made from material having a considerable elasticity, since in that case the local deformation due to the pressure of the micro-meter is often greater than the permissible variations of the examined surface. That is why in fiat-bed printing mostly a test printing-press is used, by means of which a test print is made on paper or other foil from the plate supporting the printing-forms under circumstances which imitate the operating conditions as close as possible. The hollow spots of the active surface of the printing-forms then give a too light print or no print at all. The topographical diagram of the printing surface is obtained in mirror image on another carrier. Both the latter fact and the necessity to use a test press and to have to clean the printing-forms and the ink-device time and again involve difficulties.

According to a third method a roller of rigid material and carrying a thin layer of ink is rolled over the printing form, in such a manner, that the hollow spots of the printing-form do not take up ink at all or are inked too little. The disadvantages of this method are that it is very difiicult toapply an ink-film of constant thickness onto the roller and that after each examination the printingform and the ink roller must be carefully cleaned which still does not prevent that the printing-form is gradually tinted.

Even if the printing plate should have a constant thickness in the places of the printing-elements there is .no guarantee that after the printing plate has been mounted on the plane or cylindric supporting member a satisfactory print can be made therefrom. For instance, the two-sided adhesive tape used for the attachment may have variations in thickness. Further, the supporting member may be not entirely fiat or cylindric or slightly eccentric to the axis. Also bending of the printing plate arond the cylindric surface may produce faults.

The invention has for its object to produce a simple method and apparatus, by means of which not only the flatness or the exactly concentric cylinder-shape of the surface of a flat or cylindric body but also the surface conditions of a plate or layer, e.g. a plate provided with printing-forms, mounted on such a body can be easily hid-2,4 Patented Eec. 22, 1964 "Ice examined, whereas the disadvantages of the known methods and devices are thereby entirely avoided. Said method consists in that as colouring-matter a dry powder is used. It has appeared that dry powder is easily ap plied on a roller in a layer, which has in every place exactly the desired thickness. Moreover, powder is swept or blown from the printing-form and the roller in no time, so that the cleaning involves no difficulties.

For the object aimed at powder of corn or bolus alba has proved to be very suitable for use as colouringmatter. It has also appeared to be advantageous to use powder which has been statically charged beforehand.

In accordance with the invention the apparatus for carrying out the methodsaid apparatus being provided, just as that for applying ink on the printing-form, with a roller, of which the surface is adapted to hold a layer of colouring-matter, and a device adapted toroll said roller at an adjusted constant distance from a reference surface or the axis of revolution of the cylindric supporting member over the surface of the supporting member or over the active surface of the layer or plate mounted on said member-may also be provided with a scraping member cooperating with said roller and so striking the layer of powder applied on said roller as to make the surface of said layer exactly cylindric and concentric to the axis of revolution of said roller. For holding the powder the roller may have a milled cylindric surface or be provided with a fine gauze-shaped screen.

For the elucidation of the invention reference is made to the accompanying drawing; therein is:

FIG. 1 an apparatus according to the invention for the examination of the flatness of flat printing-forms, and

FIG. 2 a like apparatus for the examination of the exact cylinder form of cylindric printing-forms.

In FIG. 1 a surface plate is designated by 1. Mounted above said plate is an exactly fiat plate 2 which is exactly parallel to said first plate. The plate 2 is pivotally connected at 3 to supports 4 and rests in the operating position upon supports 5. When the plate 2 is swung away (see the position in dotted lines) it is easy to secure thereto a supporting plate 6 provided with a printing block or form 7.

A sliding member 8 is mounted for reciprocation m the direction of the arrow 9 and back on said surface plate. Said sliding member carries a roller 1d of which the cylindric surface is milled in an extremely fine way. The roller it) is partly immersed in a trough it contain-' ing powder 12, e.g. powder of corn or bolus alba. Cooperating With the roller it is a scraping knife 13 adapted to scrape the layer of powder taken up by the roller during rotation of the roller, in such a manner, that the surface of said powder layer becomes exactly cylindric. The roller 19 is rotatably supported by its shaft 14 between'arms 15 which are pivotally connected about a shaft 16 to the sliding member 8. With the aid of an adjusting screw 17 the height of the roller can be exactly adjusted.

The roller 10 is provided with a toothed wheel (not shown), of which the pitch circle is equal to that of the roller and a thin layer of powder provided thereon. This toothed wheel meshes with a second toothed wheel 18, which is mounted for rotation about the shaft 16 and comes to cooperate with a toothed rack 19 when the sliding member 8 is moved to the left. It Will be a parent, that during further movement of the sliding member 8 the roller 10 and its layer of powder is rolled over the printing block or form 7. Powder is then brought onto said block or form except in places which are too hollow.

In FIG. 2 the printing block '7 is mounted on a test cylinder or a printing cylinder 2%. Said block may be securedto the test cylinder by means of suction. To a printing cylinder it may be attached or glued by normal means. The powder roller is mounted for rotation directly on the sliding member 8. The roller it and the test or printing cylinder are coupled by toothed wheels (not visible), in such a manner, that the layer of powder is precisely rolled over the printing surface of the print ing block 7 during rotation of the cylinder. As to the rest there is hardly any difference in construction and operation with the device illustrated in FIG. 1.

What I claim is:

1. Method of locating low and high spots in printing surfaces comprising the steps of selecting a surface to he tested, applying an uninterrupted layer of dry powder to the surface of a cylindric testing roller, making the outer surface of said layer exactly cylindric and concentric to the axis of rotation of said roller and rolling said powdered roller over said surface to be tested while maintaining the axis of rotation of said roller at constant distance from said surface to be tested, said distance being equal to the radius of the outer surface of said layer of powder.

2. The method set forth in claim 1 in which said powder is corn powder.

3. The method set forth in claim 1 in which said powder is bolus alba. v

4. The method set forth in claim 1 in which said powder is pigmented to reflect color.

5. A method of marking surfaces for printing purposes in order to determine their accuracy comprising the steps of applying a layer of powder to the surface of a cyli'ndric test roller, forming the surface of said layer into a perfect cylinder concentric to the axis of said roller, rolling said roller over said surface to be tested at a constant proximity thereto sufficient to apply small quantities of powder to accurately formed portions of said surface, and noting portions of'said surface receiving different amounts of powder.

6. The method of marking surfaces for printing purposes in order to determine their accuracy comprising the steps of applying to the surface of a cylindric testing roller a layer of dry powder having a cylindrical outer surface which is exactly concentric to the axis of rotation of said roller, rolling said powder roller so said layer of powder is in light kissing relation over the surface to be tested, whereby raised portions of the latter surface receive a greater amount of powder than lower portions thereof.

7. An apparatus for examining the flatness of a plane surface, comprising a roller having a surface adapted to hold a layer of powder, a doctor blade having an edge accurately positioned from the surface of said roller, a

bin adapted to support powder in contact with said roller, means mounting said roller for rotation to move, its

surface from said bin past said doctor blade to establish a constant thickness of powder on the surfaces of said roller, said powder having a surface concentric with the axis of said roller, slide means supporting said mounting means to move said roller across a plane surface at a constant small distance therefrom, drive means to rotate said roller at a peripheral speed equivalent to the speed that said roller is moved across said surface by said slide means, whereby said roller will apply a greater amount of powder to raised portions of said surface and a lesser amount of powder to lower portions thereof.

8. An apparatus for examining exactly the concentric cylinder shape of a cylinder surface comprising a roller of known concentric cylinder shape, means mounting said roller for rotation about its axis, a bin positioned adjacent said roller and adapted to support powder in contact therewith, a straight edge positioned at predetermined small amounts from the surface of said roller, means mounting said cylinder to be tested for rotation about its axis at a position in close proximity to said firstnamed roller its axis being parallel to said roller, and drive means interconnecting said rollers so that they rorate in opposite directions at equal peripheral speed, said first-named roller rotating in a direction that its surface moves consecutively from said doctor blade to said roller to be tested so a greater amount of powder is applied to raised portions of said roller to be tested and a lesser amount of powder is applied to lower portions of said roller to be tested.

9. An apparatus for testing for raised and lowered portions of a surface comprising a test roller of known concentric cylinder shape, a hopper adapted to support powder in contact with the surface of said test roller,

a doctor blade spaced a predetermined small distance from said roller, means to rotate said roller so that its surface passes through the powder in said hopper and then past said doctor blade so that a layer of powder is deposited on said roller having a surface concentric to the axis thereof, and said means for rotating said roller being then constructed to. drive said roller at equal surface speed over said surface to be tested and at a uniform spaced distance therefrom to deposit a greater quantity of powder on raised portions thereof and a lesser quantity of powder to lower portions thereof within a narrow range of variance.

References Cited in the file of this patent UNITED STATES PATENTS 2,118,801 Banzett May 31, 1938 2,302,179 Bronfman Nov. 17, 1942 2,434,372 Stewart Ian. 13, 1948 2,811,465 Greig Oct. 29, 1957

Claims (1)

1. METHOD OF LOCATING LOW AND HIGH SPOTS IN PRINTING SURFACES COMPRISING THE STEPS OF SELECTING A SURFACE TO BE TESTED, APPLYING AN UNINTERRUPTED LAYER OF DRY POWDER TO THE SURFACE OF A CYLINDRIC TESTING ROLLER, MAKING THE OUTER SURFACE OF SAID LAYER EXACTLY CYLINDRIC AND CONCENTRIC TO THE AXIS OF ROTATION OF SAID ROLLER AND ROLLING SAID POWDERED ROLLER OVER SAID SURFACE TO BE TESTED WHILE MAINTAINING THE AXIS OF ROTATION OF SAID ROLLER AT CONSTANT DISTANCE FROM SAID SURFACE TO BE TESTED, SAID DISTANCE BEING EQUAL TO THE RADIUS OF THE OUTER SURFACE OF SAID LAYER OF POWDER.

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