US1955673A

US1955673A - Printing machine

Info

Publication number: US1955673A
Application number: US617623A
Authority: US
Inventors: Fawdry Charles Frederick
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-07-17
Filing date: 1932-06-16
Publication date: 1934-04-17
Anticipated expiration: 1951-04-17

Description

C. F. FAWDRY April 17, 1934 PRINTING MACHINE Filed June 16 1932 2 Sheets-Sheet l April 1934- c. F. FAWDRY Filed June 16, 1932 Fatentecl Apr. 17, 1934 UNITED STATES PATENT OFFICE Application June 16, 1932, Serial No. 617,623 In Great Britain July 17, 1931 Claims.

The present invention concerns improvements in or relating to printing machines in which the printing cylinder comprises a thin sheet of metal carrying the printing surface wrapped round a a drum of the type which is divided longitudinally into a plurality of sections.

Usually, rotary reel-fed photogravure machines employ printing cylinders in which the printing surface is formed upon the outer surface of a comparatively thick copper sleeve which is mounted upon a steel drum carried by or formed on a steel shaft. These sleeves are very expensive to prepare. It is recognized that if the surface of a thin metal sheet (or design plate as it is frequently termed) wrapped round a drum could be employed as the printing surface considerable advantages would result. Various attempts have been made to obtain these advantages, but difficulties have been encountered due to the difliculty of tensioning the thin design plate and holding it properly tensioned and truly cylindrical during use.

Objects of the present invention are to provide for the rapid tensioning of such a thin plate, to 5 provide for the plate remaining properly tensioned and cylindrical even after considerable use, and to provide plate supporting and tensioning means which shall be comparatively easy and cheap to construct and maintain.

The invention will become apparent to those skilled in the art from the following description in conjunction with the accompanying diagrammatic drawings, of one-illustrative construction according to the invention.

' In the drawings,

Fig. 1 is a cross-sectional end elevation of one illustrative drum with a design plate in place;

Fig. 2 is an end elevation similar to Fig. 1, with the lifting gear in place and the drum opened;

Fig. 3 is a front elevation, partly in section, of part of the drum of Fig. 1; and

; Fig.4 is a detail in perspective showing the means for holding the design plate in place on the drum.

The-construction about to be described includes a printing cylinder indicated generally at 1 (Fig.

3) that comprises a steel drum indicated geneially at 3 carried by the cylinder shaft 5 and a thin sheet of copper 7 (design plate)- which is wrapped round the drum 3 and'which carries theetche'd printing surface. The drum 3- is divided diametrically (along a horizontal diameter asindicated in Fig. 1) into two sections, an i upper'section-lland a lower section 13. The

lower section 13 is, in this particular instance, formed integrally with the shaft 5. Considering Fig. 1 there is projecting upwardl from the middle portion of the top surface of the lower section 13 a hump 15 that extends along the whole length of the section. The left hand side (as viewed in Fig. 1) of the hump is vertical at 1'7 but has its top corner rounded oif at 19. to meet the horizontal top surface 21 of the hump. Immediately to the left of the hump there is, in the top surface of the lower section 13, a rectangular notch 23, the right hand side 25 of which is in vertical alignment with the left hand side 1'7 of the hump. This notch extends along the whole length of the drum. The right hand side 27 of the hump slopes downwardly and outwardly so that the hump is widest at its base. About midway between the right hand base of the hump 15 and the right hand edge of the section 13 there is a rectangular recess 29 which extends along the whole length of the section and in which is fixed, by means of screws, a plate 31 that carries at intervals of about four inches a number of hooks 33 pointing inwardly. Near the right hand top corner of the hump 15 is a row of brackets 35 cast with the hump, each bracket having a similar hook 37 pointing upwardly; alternatively there might be a plate similar t plate 31.

The upper section 11 of the drum has its middle portion cut away to form a hollow 41 for the reception of the hump 15. The base 43 of the hollow 41 is adapted, when the two sections are closed firmly together, to rest upon the horizontal top surface 21 of the hump. The part 45 of the section 11 adjacent to the part 19 of the hump is cut away sothat it does not contact with the hump. The left hand margin 47 of the hollow adjacent to the vertical side 17 of the hump is vertical. Projecting downwardly from the lower left hand face of the upper section 11 is a rib 51 having a vertical left hand margin 52; the right hand margin 53 of the rib is slightly backed'off so as not to contact with the right hand margin 25 of the notch 23. The arrangement is such that the left hand margin 52 of the rib and the left hand vertical face 4'7 of the hollow 41 will by contact with the adjacent surfaces of the low-- er section 13 locate the two sections relatively to one another in a horizontal diametrical direc-' tion; the base 43 of the hollow 41 and the top 21 of the hump position the two sections relatively on a vertical diameter. Thus when the sections are together they will form a cylindrical drum. The lower face 55 (Fig. 2) of the upper section 11' to the right of the hollow ll and the adjacent upper face 57 of the lower section 13 to the right of the hook-receiving recess 29 are cut away somewhat to permit of the insertion of the design plate 7; the lower section 13 may have projections as 59 (Fig. 2) to act as bearing faces for the two sections when the two sections are closed.

The parts are assembled as follows:-

The design plate '7, the upper section 11 being raised about an axis outside its left. hand edge, is wrapped round the drum. The lower margin of the sheet '7 is hooked on to the hooks 33 in the recess 29 by means of a rod 61 (Fig. 4) attached to the said margin; the upper margin of the sheet '7 is similarly hooked on to the hooks 37 on the hump, see Fig. 2. The upper section 11 is then lowered to close upon the lower section 13 and in doing so it stretches the design plate tightly round the drum in correct position for printing, see Fig. 1. The adjacent

left hand corners

63 and 65 of the two sections are then in contact so that there is no gap or depression in the drum surface at that location between the sections. In consequence no depression will be formed at the corresponding location in the design plate '7 by the impression cylinder during printing. A piece of leather 66 is placed between the sections 11 and 13 and is afterwards smoothed with a hot iron so that it forms a continuation of the sections such that the doctor can ride over the junction between the sections readily.

In order to force and hold the two sections 11 and 13 of the drum together each end of the drum is provided with the following devicez-The end of each section has formed on it an axiallyprojecting boss as '71 (Fig. 3) the adjacent bosses forming together a single boss in the form of a truncated cone with its smaller diameter at the end remote from the'drum. The adjacent portion of the shaft 5 is screwed at '73 and is provided with a heavy nut having an inwardly-projecting annulus '77. This annulus '77 is provided externally with a light nut '79 between which and the adjacent face of the heavy nut 75 is formed a recess 81; in this recess 81 lies loosely a flange 83 that projects towards the axis of the shaft 5 from a ring 85 the inner surface of which is coned to correspond to the shape of the coned boss 71. The arrangement is such that when the upper section 11 of the drum is positioned on the lower section 13, the coned ring 85 is forced by means of the large nut 75 on to the coned boss 71 so as to force the two sections of the drum closely together. By rotation of the large nut '75 in the reverse direction the coned ring 85 will (through the light nut '79) be positively drawn off the coned boss '71 to release the sections.

The jig or hinge device for opening the sections of the drum will now be described; this device is in two parts, one part for attachment to each end of the drum, and consequently it will be necessary to describe the part at one end only. Two arcuate bands 91 and 93 (Fig. 2) are provided which, when the coned ring 85 is withdrawn from the boss 71, are attached by means of setscrews 95 (having knurled heads so that they can readily be manipulated by hand) to the end of the adjacent section and are tapered to fit on the coned boss 71, one band being attached to each of the drum sections. The left-hand ends of the bands 91, 93 (adjacent to the rib 51 and notch 23) are bent outwardly from the drum axis and are provided with over-lapping apertured bosses as 97 which are hinged together by means of a hinge pin 99; the axis of the hinge pin is parallel or approximately parallel with the axis of the drum and lies in line with the horizontal diameter of the drum along which the sectional division of the drum occurs. The other end of the band 91 has an outwardly-projecting extension 101 which when the drum is closed lies approximately parallel with the diameter of drum division. The outer end of this extension has one end of a chain or a link 103 connected to it, the other end of which is provided with a hook which is adapted to hook over a projection extending from the bearing of the impression cylinder shaft. This bearing, as is usual, is mounted in up-and-down guide ways so that it can be moved towards and from the printing cylinder as is customary. The arrangement is such that when it is desired to open the printing drum for the attachment or removal of a design plate, the

hinge device

91, 93 is attached to the sections of the drum at each end, the hook is hooked on to the projection of the impression cylinder bearing, and the impression cylinder is moved away from the printing cylinder in usual manner. As a result the upper section of the printing drum is rotated about the axis of the hinge so as to raise the said section and remove tension from the design plate as in Fig. 2 so that the margin of the latter can be unhooked and the design plate removed. By the use of such a hinge the jointing faces may be opened by pivoting but the said faces may yet fall upon a radius of the drum so as to give the strongest edges possible; as the axis of movement is outside the drum these edges are not in contact during opening and so are not liable to be broken off.

It will be appreciated that by reason of the foregoing construction a base for the design plate is obtained which is cylindrical except at the location where the margins of the design plate pass inwardly into the interior of the drum for attachment; the joint (at 63, 65) between the sections on the opposite side of the drum is completely closed so that no longitudinal depression in the design plate is formed by the impression cylinder at that location. Consequently the design plate can be used as a continuous printing surface all around the cylinder except at the attaching location mentioned.

It is to be observed that the amount of slack produced in the design plate '7 for a given opening of the section 11 (restricted in practice by the limited amount by which the superposed impression cylinder can be lifted) is about twice that obtained with known arrangements in which the ends of the plate are anchored to different sections of the cylinder. This additional slack facilitates the lifting of the plate off the somewhat inaccessible anchoring hooks without bending said plate sharply and so risking damage'to its printing surface.

What I claim is:

1. Printing cylinder, comprising two separable complementary sections which together form a cylindrical drum, a flexible design plate Wrapped around said drum, anchoring means attaching both margins of said design plate to one and the same section of said drum and means for secur ing said sections together in drum form with the design plate tensioned around the same.

2. Printing cylinder, comprising a drum divided longitudinally into two sections separable by a rotary movement of one section in relation to the other about an axis to one side of said drum, the line of division at the cylinder surface on that side of the drum being substantially radial so that the sections fit together at said surface without gap and without sharp angles, a flexible design plate wrapped around said drum, anchoring means attaching both margins of said design plate to one and the same section of said drum, and means for securing said sections together in drum form with the design plate tensioned around the same.

3. Printing cylinder, comprising two separable complementary sections which together form a cylindrical drum, a flexible design plate wrapped around said drum, anchoring means attaching both margins of said design plate to one and the same section of said drum, and means for securing said sections together in drum form with the design plate tensioned around the same, said securing means consisting, at each end of the drum, of an externally coned boss on the drum-sections, an internally coned and flanged ring engageable over said boss to draw the drum sections together, and a nut provided with flanges located one on either side of the ring-flange and thereby adapted both for engaging said ring over said boss and for disengaging said ring from said boss.

4. Printing cylinder comprising a drum divided longitudinally into two sections separable by a rotary movement of one section in relation to the other about an axis located outside of said drum, a flexible design plate wrapped around said drum, anchoring means attaching both margins of said design plate to one and the same section of said drum, and means for securing said sections together in drum form with the design plate tensioned around the same.

5. Printing cylinder comprising a drum divided longitudinally into two sections separable by 1'0!- tation of one section relatively to the other section, a flexible design plate wrapped around said drum, anchoring means attaching both margins of said design plate to said other drum section and a hinge device for said drum sections having its axis outside said drum, by means of which device said one drum section can be rotated in relation to the other for tensioning and releasing the design plate.

CHARLES FREDERICK FAWDRY.