US1562470A

US1562470A - Doctor-operating gear

Info

Publication number: US1562470A
Application number: US37165A
Authority: US
Inventors: Owen Malcolm
Original assignee: Individual
Current assignee: Individual
Priority date: 1925-06-15
Filing date: 1925-06-15
Publication date: 1925-11-24
Anticipated expiration: 1942-11-24

Description

Nov. 24, 1925.

M. OWEN DOCTOR/ OPERATING GEAR Filed June 15, 1925 2 Sheets-Sheet 1 Livenion 12 0m en-W Alton/29y Nov. 24, 1925- 1,562,470

' M. OWEN DOCTOR OPERAT ING GEAR Filed June 15, 1925 2 Sheets-Sheet 2 Patented Nov. 24, 1925.

UNITED STA PAT MALCOLM OWEN, on LONDON, ENGLAND.

nooron-ornnarme GEAVR. I

Application filed June 15,' 1925. Seria1 No. 37,165.

To all whom it-ma-y concern:

Be it known that I, MALCOLM OwEN, a subject of the King of Great Britain, residing at 109 Farringdon Road, London, E. C. 1, England, have invented certain new and useful Improvements in Doctor-Oper ating Gears, of which the following 1s a specification. v

This invention relates to improvements in the construction of rotary intagllo or photogravure printing machines, more especially of the type employing a detachable metal sheet wrapped around a prlnt ng cylinder; such machines employ a knife, commonly referred to as a scraper blade or doctor, which scrapes the ink off the surface of the cylinder except where the engraving occurs. In the case ofa sheet wrapped around the cylinder, .a gomt occurs over which the doctor is lifted.

In machines of the class named it has hitherto been usual to bring about the necessary pressure on the doctor by means of springs or weights applied to the pivot spindle about which the doctor works, but this is opento the objection that the pressure required causes a considerable bending of the knife between the line where it leaves its support and its contact with the; cylinder, thus requiring extra movement on the weight or spring liftin mechanism to lift the knife clear ofthe cy inder.

Unless accurate timing of the lift is provided the speeds of running the machine are much limited.

The main object of the present invention is to improve the method of applying pressure to a doctor so as to eliminate, uneven wear, and another object is to improve the means of controlling the doctor so that an efficient rise of the doctor during the passing of the joint in the cylinder surface at relatively high speed is obtainable.

1 According to the present invention an improved method of pressing the doctor or scraping knife on to the printing surface of an intaglio printing cylinder is employed, in flexing the knife a substantially continuous line thereon beticvlveen its operating edge and its clamped e e. i

. 'Ihe flexing of the knife may. be effected by pressure from above, or by a pull from beneath, but-preferably in any case so that when the pressure is removed, the knife is the printing surface. The additional and 'tion, a slight left in a position to wipe the cylinder andleave a thin film of ink'over the whole of accurately controlled pressure applied according to the present invention will then remove the thin film, 1n the engraved surface.

By judiciously applying the pressure tothe kn1 e to flex it from the initial position when a film is left on the cylinder to the scraplng position, the return of the knife to initial position can be obtained by the springlness in the knife as soon as the pressure is relieved, and by this means the doctor can be controlled so as to be lifted very quickly. 'Then when the invention is applied to cylinders having a gap, that is,

printing cylinders in which the printing surface iswrapped around the cylinder, the

release of the pressure can be timed; so that leaving the ink only i the knife is retracted from the cylindert as the gap passes under it, and qulck movement of the knife, a speed something like ten thousand revolutions er hour can be run with a large cylindhr,

whereas at present speeds only half that number are possible with the mechanism at present emplo ed.

It should e understood in connection with this art that a scraper knife as used in modern intaglio printing is very thin, say '6/1000 of aninch to get a clean, free surface during the final scraping. In practice, therefore, it'is seldom found to bequit straight on its edge, and to'leave even a thin film of any regularity all over the cylinder, for a normal setting as required according-to this invenreliminary flexing isdesirable, so that w en the final flexing occurs, the scraper has less ink to remove, and there is less movement of the scraper to non-scraping position. a

In the accompanyin drawings is illustrated by way of examp e one preferred conowing to the thick only, in order struction' .for carrying the invention into effect;

Fig. .1 is a' sideelevation showing the parts n operative position; and Fig. 2 is a similar view sure gear in inoperative position;

Fig. 3 is an end elevation of the machine shown in Fig. 1; and

Figsl 4 and 5 show in side elevation and end elevation respectively means for adjusting the doctor knife in its support, Fig. 5

showing the pres- N being a view from the left-hand side of.

Fig. 4.

he construction shown comprises the ordinary cross shaft 1 for a doctor 2 held in initial-position by a lever 3 and spring 4: in

co-operation with an adjustable screw 5 and fixed stop 6. The spring {1 pulls the screw surface of plate 1 on the cylinder 1. Such apparatus includes a cross shaft 7 supporte in the frame 8 of the machine, above the doctor, and on this shaft 7 is fixed a plate 9' (see Fig. 4) which itself is provided with w an adjustable and flexible member 10 (hereafter referred to as the presser member) which bears on the doctor 2'; the plate 9 is fixed to theshaft 7, which latter is square except in its bearings, by screws 83 working through slotted holes in the said plate; the presser member 10 is preferably slotted so as to be clamped in position of adjustment between the plate 9 and a clamping bar 9 by screws 34.

On the shaft 7 is fixed an operating arm 11 so that when the arm' 11 is rotated in a clockwise direction the plate 9will be moved so as to press the flexible edge of the presser member 10 on to the'doctor; therefore it will be observed that the presser member.

10 acts as one a rml of a bell crank, of which the-other arm is the member 11. The adjustment of the member 10 relative to the doctor is such that the pressure \on'the doctor is about midway between itsi free or operating edge audits support 29, so as to cause the knife to bend and to give sufiicient pressure on the doctor that the latter will completely remove the thin film of ink, as previously mentioned.

The movement of the arm 11 and the pressure on the member 10 is obtained by a reciprocable member, e; g., a long link 12 diametrically arranged with regard to the cylinder and guided, say, bya slot 13 therein passing over the cylinder shaft 14:, the re- 'duced end of which is indicated at 1 1", and. supporting at its end a lever 15 carrying a slidable weight 16 which is adjustable as regards its distance from pivot 17 of thelever; the said link 12 is loosely connected to arm 11, and to this end carries a pin 30 which engages'in an open slot 11 in the end of the arm .11. provided with a projecting lug 18 in which is threaded the screw 18, the end of which is provided with a block 18", which block restson a disc 32, mounted on the shaft 14 which is :the shaft carrying the cylinder 1 The link 12 is further 7 so that by adjustment of the screw 18, the downwardtravel of the link 12 is regulated and thereby the amount of pressure of the member 10 upon the doctor 2;

For intermittently raising the doctor so that its rising movement occurs just before and when the gap 1 in the surface of the cylinder 1 is passing thereunder, a cam 19 rotating synchronously with the cylinder is employed, and preferably the cam is carried by a disc 20 rotatably mounted on the reduced end 14* of the cylinder shaft 1 1. The cam 19 operates with a bowl 21 on the said connecting link 12, so that as the member 20 rotates the cam 19 in passing under the bowl 21 lifts the bowl and thereby the link 12, the movement of which is transmitted through arm 11 to the presser member which thereon. is lifted from the. knife, al-

lowing the knife to straighten out by its own springiness and to return to its preliminary position in which only the thin film of ink is left on the cylinder.

In cases where a gap does not occur in the cylinder but where there are non-printing surfaces, the lifting of the doctor will be timed to correspond with the moment when such surfaces pass thereunder.

The presser member lO-is preferably reinforced by a metal plate 22 (as clearly shown in Fig. 4) to give it the necessary rigidity, and since it works substantially over the full length of the doctor, improved scraping is achieved, and "a longer life for the knife by reason of the pressure being applied centrally.

Adjustment for the cam 19 for the pur-' pose of varying the stroke of link 12 and thereby the lift of presser member is preferably obtained by providing the cam 19 with grooved ends which slide on walls of slot 23 formed in the disc 20; by means of a screw-threaded stop 24 carried in the base of the slot the cam may be moved to or from the axis of the cylinder. I

A handle 25 fixed to shaft 7 is preferably employed for lifting the presser member when cam 19 is not operating; by moving handle 25 the-shaft 7 is rotated in its bearings; screws 26 threaded in lugs'7 (Fig. 4) fixed on the shaft 7 serve toadjust the edge of the presser member 10 in position on the doctor between the sup ort 29 and the free edge of the doctor." gimilarly, screws 27 working in threaded holes of the bracket 31 on-the cross shaft I serve to push or retract the doctor 2 to or from the cylinder 1.

When the support 29 has been adjusted it is fixedin' selectedposition by lever screw 28.

It will be seen that in' operation of a machine according to this invention two ad-- the operating edge of the doctor and its 1 A method of flexing a doctor supported in contact with the printing surface of a printing cylinder to effect complete wiping of the printing surface, consisting in applying pressure independent of the doctor support along a line completely across the doctor from side to side between the operating edge of the doctor and its support.

2. Apparatus for flexing a doctor-supported in contact with the. printing surface of a printing cylinder to effect complete wiping of the printing surface, comprising a presser member having a pressing edge applied com plctelyacross the doctor from side to side between the operating edge of the doctor and its support and independent of the sup port and means for varying the pressure applied by said presser member.

3. Apparatus for flexing a doctor supported in contact with the printing surface of a printing cylinder to effect complete wiping of the printing surface, comprising a presser member having a pressing edge applied across the doctor from side to side between support, means for varying the pressure applied by said presser member, and intermittently operated means for rapidly retracting said presser member from said doctor.

4. Apparatus for flexing a doctor support-- ed in contact with the printing surface of a printing cylinder to efi'ect' complete wiping of the printing surface, comprising in combination with a'pre'sser member having its pressing edge applied across the doctor from side to side between the operating edge of the doctor and its support, a reciprocable member, of means for intermittently operatsaid reciprocable member in synchronism with revolutions. of the printing cylinder, connecting means between the presser Jnember and the reciprocable member, wheres by thereciprocations of the said member are utilized to retract the presser member from the doctor, thereby allowing the latter to unflex, and means forvarying the pressure, applied by said presser'member.

5. Apparatus for flexing a doctor supported in contact with the printing surface of a printing cylinder to effect complete wiping of the printing surface, comprising in combination with a reciprocable member and .meansfor operating said member intermittently in synchroni'sm with revolutions of the printing cylinder, of a presser member having its pressing edge applied across the doctor from side to side between the operat ing edge of the doctor and its support, connecting means between the presser member and the reciprocable member for positive ly communicating the movement of the reciprocable member to the presser member, so that in one direction of movement of the re ciprocable member the presser member is forced on to the .doctor to flex it as set forth,

and-in the other direction of movement of v the reciprocable member the presser member is retracted therefrom to alloys the doctor to unflex, and means for vary ng the pressure applied by said presser member.

6. Apparatus" for flexing a doctor supported in contact with the printing surface of a printing cylinder to effect complete wiping of the printing surface, comprising in combination with a reciprocable member and means for operating said member intermittently in synchronism with revolutions of the printing cylinder, of a presser memher having its pressing edge applied across the doctor from side to side between the opv crating edge of the doctor and its support, connecting means between the presser memher and the reciprocable member for positively communicating the movements of the reciprocable member to the, presser member,

so that in one direction of movement of the reciprocable member the presser member is forced on to the doctor to flex it as set forth, andzin the other direction of movement of the reciprocable member the presser member is retracted therefrom to allow the doctor to unflex, and means for varying' the length of stroke of the reciprocable member by which the presser member is forced to the doctor, whereby the pressure applied by said presser member is variable.-

7. Apparatus for flexing a doctor'sup-' ported in contact with the printing surface of a printing cylinder 1 to effect complete wiping of the printing surface, comprising in combination with a reciprocable member, cam gear for intermittently raising said member, gravity means for effecting its return, and an adjustable stop for varying its travel during said return, of a presser memthe doctor from side to side between the operating edge of the doctor and its support, a loose connection between said presser member and the reciprocable member,

whereby the action of gravity on the latter applies the presser member'to the doctor when the said cam gear is inoperative.

8. Apparatus for flexing a doctor supported, in contact with the printing surface of a printing cylinder to effect complete wiping of the printing'surface, comprising in combination with arecipro cablemember,

. ber'having its pressing edge applied across cam gear for intermlttently raising said member mcludmg an ad ustable cam forvarying the lift im arted to said member, gravity means for effecting its return, and an adjustable stop for varying its travel during said return, of a presser member having its pressing edge applied across the doctor from side to side between the operat ing edge of the doctor and its support,,a loose connection between said presser member and the reciprocable member, whereby the action of gravity on the latter applies the presser member to the doctor when the said cam gear is inoperative.

9. Apparatus for controlling a doctor op erating on the printing surface of an intaglio printing cylinder, pressing means for applying, by a preliminary flex of the doctor, a normal adjustment to the said printing surface, in combination with means for applying direct to the doctor from side to side between the operating edge of the doctor and its support, a force which efiiects a further flexing of the doctor to obtain the scraping contact proper, and intermittently operated mechanism for removing the pres-' sure of the said force at such tlmes as a non-I printing surface passes under the doctor reinstating said normal adjustment.

1(). The combination in an intaglio printing machine having a metal printing sheet attachment to the cylinder, of a doctor normally adjusted by regulating screws to give a slight preliminary flex thereto, a link in-.

termittently reciprocated diametrically of the cylinder, of a presser member having its pressing edge applied across the doctor from side to side between the operating edge of the doctor and its support, and an oper-- ture.

' MALCOLM OWEN.