US2241120A - Engraving - Google Patents

Description

J. W. DALTON May 6, 1941.

ENGRAVING Filed Nov. 5, 1937 5 Sheets-Sheet 1 E llllll 2f WM J. w. DALTON May 6, 1941.

ENGRAVING Filed Nov. 3, 1937 5 Sheets-Sheet 2 y 6{1941- J. w. DALTON 224L120 ENGRAV ING Filed Nov. 3, 1937 5 Sheets-Sheet 3 May-6, 1941' J. w. DALTON 2,241,120

ENGRAVING' Filed Nov. 3, 1937 5 Sheets-Sheet 4 zdwpama dfi y 6, 1941- J. w. DALTON 2,241,120

' ENGRAVING Filed Nov. 5, 1937 5 Sheets-Shet 5 l l Hllllll l I l l l I l [I HI I l I lllllllllllllllllllmll Wis.

Patented May 6, 1941 John Willey Dalton, London,

England, assignor to The Daily Mirror Newspapers Limited, London,

England Application November 3, 1937, Serial No. 172,626 In Great Britain November 6, 1936 3 Claims. (01. 96-12) This invention relates to engraving and particularly to engraving by means of photomechanical processes, with a view more especially to the production of engraved surfaces adapted for use inprinting processes.

In the production of engraved surfaces by photo-mechanical processes a metal surface is provided locally with a resist formed on the plate by a photographic process which causes certain portions of a coating applied to the plate to become insoluble and thus to operate in pro- .tecting the corresponding portions of the plate from the action of an etching fluid the remaining portions of the coating being washed away leaving corresponding areas unprotected so that they may be attackedby the etching fluid.

If deep etching is resorted. to a considerable amount of time is consumed in the etching process and, moreover, steps have to be taken to ensure that portions of the metal surface which it is desired should not be attacked by the etching fluid remain protected during the etching operation.

' In certain cases and more particularly for coarse work, the depth to Which the plate is engraved may be increased and thus the etched :portions are brought into greater relative prominence or relief with the aid of a router the operation of which upon the plate is controlled by the judgment of the operator.

In so far as printing surfaces are concerned a somewhat similar effect in the resulting impression obtained may be secured by what is known as underlaying, that is to say, by the local removal of metal from the back of'the plate one face of which constitutes'the printing or impression-producing surface, and subsequently sub- J'ecting the plate to heavy pressure, whereby those portions of the plate which have been thinned down by the operation effected upon the back of the plate will be forced downwards from the face of the plate.

The object of the present invention is to provide improvements in the production of engraved surfaces and more particularly such as are adapted for use in printing processes, by methods involving the production of an image in relief by, for instance, etching and more especially by photo-mechanical methods as in the production of line blocks.

The invention consists, broadly, in the method of producing engraved surfaces in which an image in relief is formed on a metal plate by,

for instance, an etching operation and the surface of the plate or the like provided with the or mainly mechanical'may be employed for the fpur pose. V

Alternatively, electrical means may be employed arid, for instance, such as involve electromechanical action.

surface of a cutting tool arranged to increase the effective prominence or relief of the image or the elevated portions of the surface.

The scanning operation in accordance with the invention may be applied in controlling the action of a cutting tool on the surface of the plate bearing the image or, as in underlaying, on the rear surface of the plate 7 In the former case the provision of means for securing a delay between the action of the mechanical scanning device on a particular area and the operation on or in the immediate vicinity of that area, of the cutting tool will be resorted to while in the other case the provision of such means may be dispensed with.

The means for securing a delay between the action of the mechanical scanning device on any given area and the operation of the cutting tool on or in the vicinity of the area may be of any appropriate character.

Thus, for instance, mechanism which is wholly ,Forinstancathe scanning device may be arranged togcontrol the local magnetisation of a moyingjvheel, disc, band or the like, the varia- Ytion in magn tism of portions of which will in thejtravel of-the-wheel, disc or band cause the "cutter, tooperate on or in the immediate vicinity of the particular area corresponding with a given section ofthe wheel, disc, band-or the like.

A like effect may be secured by the provision .in', a moving member of a plurality of elements adapted tube displaced by the scanning device and subsequently as the result of their displaceinent to cause the cutter to operate on or in the immediate vicinity of the area in the surface by which the displacement of the element was produced. j

-Tl1us,-'inaccordance with the invention, a moving-member inthe form, for instance, of a disc with which there is associated a plurality of displaceablepins-fiormred of, magnetic material may be; arranged in association with an electromagnet adapted to be energised by the scanning device in orderto'effec't displacement of the pins and-with means adapted to cause the pins so displaced, after they have influenced the operation of the cutting tool, to return to their initial position.

The scanning device, in accordance with the invention, may comprise a feeler or reader between which and the surface bearing the etched image relative motion is secured, the feeler or reader being, for instance, in the form of a pin furnished with a somewhat flattened spherical end adapted to project through an aperture in a support having a plane surface which in the operation of the device bears upon the face of the plate on which the etched image has been formed. I

With such a construction the pin may be arranged, as the result of its displacement due to variations in level of the plate, to actuate a movable contact element included in an electric circuit connected with means whereby the cutting tool may be moved into a position to operate on the plate.

For instance, a movable contact member may be arranged on an arm adapted to be displaced by the movements imparted to the pin consequent upon the local variations in level of the surface of the plate bearing the image thereby establishing or interrupting an electrical circuit in which is included an electro-magnet or solenoid associated with an armature adapted by its motion to advance, in opposition to a spring or the like, a rotary cutting tool into a position in which it will operate upon the plate.

The rotary cutting tool may be of the character described and claimed in the British specifications Nos. 389,102 and 17,107/35 (458,112).

Where such an arrangement is used for underlaying, the pin and the cutting tool may be arranged in line on opposite sides of the plate, the

electro-magnet and cutting tool being, for instance, resiliently supported and furnished with surfaces adapted to bear against the general level of the rear surface of the plate, while the pin is associated with a member pressed firmly upon the opposite surface.

A device including delay mechanism may comprise a cylinder or table by which the etched plate is supported in association with means for securing relative motion between the plate and a mechanical scanning device which may be in the form of a pin or feeler adapted, by its movement in accordance with the local variations in level of the surface of the plate, to control the relative position of electrical contacts arranged in a circuit including a source of supply of current and a magnet or solenoid the armature of which is adapted to displace pins slidably secured in a disc to which rotary motion at an appropriate speed is imparted in such manner that each individual pin which has been displaced by the magnet or solenoid will cause a rotary cutting tool to be moved in opposition to a spring into a position to operate on or in the immediate vicinity of the corresponding area of the plate, means being provided for re-setting the displaced pins after they have performed their function in relation to the movement of the cutting tool.

It will be understood that the delay mechanism above described may be substituted by any suitable means for compensating for or neutralising the efiects resulting from the spacing apart of the point being read at any instant and the point operated on at that instant by the cutting tool.

The invention will be described in detail with refhierlence to the accompanynig drawings in w. c

Figure 1 is a view in horizontal section of one construction of apparatus in accordance with the invention,

Figures 2 and 3 are views in section on a larger scale of certain elements of the said construction,

Figure 4 is a fragmentary view of an alternative construction,

Figures 5 and 6 are views in sectional elevation and in end elevation of a further alternative construction.

In Figure 1 the plate I under treatment by the scanning and engraving device indicated generally by the reference 2 and illustrated on a considerably enlarged scale in Figures 2 and 3 with reference to which it will be described in detail, is arranged so that it may be moved continuously from left to right and at intervals stepwise at right angles to this direction and thereafter from right to left and so on until the scanning and engraving operation is completed.

The plate is supported with one edge engaged in a guide 3 on the arm 4 which is adjustably mounted on the cylinder 5 so that it may be moved into the appropriate position to engage the edges of plates of difierent dimensions, bein clamped in position by locking means 6 actuated by the handle I. From the cylinder 5 extends a fixed arm 8 on which is slidably mounted a rest 9 with which the opposite edge of the plate is secured by pins I0 and this rest is provided with a rack ll engaging a pinion l2 on a spindle l3 on which is arranged a spur wheel l4 engaging a pinion l5 formed on the bush [6 rotatably of the cylinder and permit the escape of liquid from the opposite end thereof.

The liquid is supplied to the tube by way of the pipe 2| from the pump 22 driven by the motor 23 and the liquid is returned by the pipe 24 to the tank 25 from which it is withdrawn by the pump.

The direct flow of water through the tube I1 is prevented by the provision within it of a valve 26 on a spindle 2'! and this valve is formed with passages 28 adapted according to the position into which it has been rotated to permit liquid to enter the cylinder at the right or left hand side of the valve and to exhaust from the opposite side so that in the former case the cylinder and thus the plate which is being operated on will move from left to right and in the latter case from right to left.

This alternation in the direction of motion of the plate will be effected at intervals which correspond with the completion of the treatment by the scanning and engraving device of a line or zone extending from one side of the plate to the opposite side thereof and after the plate. has been moved in a direction from top to bottom of each line or zone of the plate has been completed. Thus when the plate is moving from 2,241,120 'right' to left the stud 29 will contact with the spindle 30 which is splined and passes through the bush l6. In bearing upon the spindle 30 it will cause the sides of the teeth of the splined element 3| to bear against the sides of similar teeth formed within the splined bush 32 which is furnished on its exterior or peripheral surface with slow pitched grooves engaging similarly formed webs 33 in such manner that axial movement of the bush in opposition to the spring 34 will cause it to rotate and thereby permit the teeth within it to engage in the recesses between the teeth of the element 3|. The compression of the spring will thereupon be released and the bush will move axially with the result that it will rotate the spindle 30 which in turn will rotate the pinion l5 and in turn rotate the'spur wheel M on the spindle of which there is secured the pinion l2 which is in engagement with the rack II and in' this way movement is imparted to the rack and the carrier for the plate I to such a degree that the plate is brought into position for the next adjacent line or zone of the plate to be operated upon by the scanning or engraving device.

When the plate I reaches the opposite end of its travel a similar result, that is to say, a movement of the plate in a direction at right angles to the direction between right and left, is eifected in consequence of the abutment 3| on the spindle 30 causing the sides of the teeth of the splined element 31a to bear against the sides of similar teeth formed within the splined bush 32a which is furnished on its exterior or peripheral surface with slow pitched grooves engaging similarly formed webs 33a and motion imparted to the spindle will thereby compress the spring 34 thereby causing the splined bush to rotate and permit the teeth within it to engage the recesses between the teeth of the element 3 la, the compression of the spring when released operating to move the bush axially with the result that it will rotate the spindle 30 through 180 and in the same sense as that in which it is rotated when the spindle is moved in the reverse direction.

On the spindle 30 there is mounted a spur wheel 35 which is in engagement with the pinion 36 provided on the valve spindle 27. Consequently rotation of the spindle 35 will caus rotation of the valve spindle 21 and thereby alter the position of the valve to change the direction of motion. of the cylinder and the means for supporting the plate which is being operated upon.

In addition, the rotation of this valve spindle on the end of which there is secured a commutator 3'! co-operating with fixed con- tact elements 38, 39, 40, operates to cut out of circuit one, and put in circuit the other, of the two scanning devices, the leads 4| and 42 of which are connected with two of the fixed contacts, while the third fixed contact is connected by the lead 43 with a winding 44 and through the winding with a source of alternating current 45, the other lead 45 from this source of current extending to the scanning devices.

The winding is the winding of an electro-magnet in the field of which there is arranged a steel disc '4'! on a spindle 48 driven by the hydraulic motor 49 arranged in the connection between the pump 22 and the pipe 2! leading to the tube [7.

When current is caused to flow through the winding in question a magnetic field is set up and the disc 47 is locally'magnetised and at the appropriate instant the magnetised portion comes into register with a second electro-magnet 50 connected by leads 5| with theigrid circuit of the amplifying valve 52 to the anode of which high tension current is supplied from the source 53 through the resistance 54, the anode in turn being connected through the condenser 55 and rectifiers it and grid bias battery or the equivalent 5?, with the grid of the gaseous discharge tube 53, the anode of which is connected with 'the generator 59 which in turn is connected by the lead 50 with one end of the engraving device subsequently to be described, the other end of the winding being connected with the common lead to the cathode tube and gaseous discharge tube, the circuit including the tubes being of well-known type.

In order that a record of the signal which is impressed upon the disc 41 may, after it has performed its function in setting into operation the vah'e circuit above referred to, be obliterated or removed, with the disc there is associated a third electro-magnet 6| connected by the leads 62 with the generator 63, the position of this electro-magnet being such that it comes into operation on the disc at the appropriate time.

The mechanism of the scanning and engraving device is more clearly shown in Figures 2 and 3.

In these figures the plate i is shown with its edges engaged in the manner above described in a guide 3 and a rest 9 and below it there is arranged a body 6-1 in which are provided two scanning elements of identical character. Each of these scanning elements comprises a guide 65 or 65a having a flat surface 66 or 66a and a spherical surfaced portion 81 or 6111 permitting it to rock in the spherically surfaced recess 68 or 68a.

Further, each of the scanning devices comprises a pin 69 or 69a having a ball head 18, 10a which is forced into contact with the surface of the plate by a spring H or 'lha one end of which bears upon the base of a recess 72 orlZa and the other end upon an enlargement IS-13a on the pin. On the enlargement is furnished a contact ring 14 or 14a connected by a lead 4! or 42 to one of the fixed contacts 38 or 39, and with each of these rings there is associated a ring 15 or 15a connected to the lead 46 which is connected with the source of alternating current 55 which in turn is connected with one end of the winding 44 the other end of which is connected with a fixed contact 40 (see Fig. 1) cooperating with the commutator 36, so that either the one or the other scanning device is cut out, and the other is included in the circuit with the generator, according to which direction the plate is travelling.

As will be seen, the springs forming part of the scanning devices operate to force the heads of the pins into contact with the plate and when there is a recess or depression in the circuit of the plate, the heads of the pins will enter the recess and establish an electric connection between the contact elements thereof and thereby permit current to flow through the winding 44 whereby a magnetic field being set up, the steel disc 41 will be locally magnetised and in its rotation such magnetised portion will influence the winding of the electro-magnet 50 and thereby operate through the amplifier, rectifier and gaseous discharge tube circuit in such manner that the output from the circuit will cause current to flow through the winding 76 of the engraving device. The energising of this winding will impart motion to th pin 11 in opposition to the spring 18 one end of which bears upon an abutment upon the pin and the other end upon abutments I9 provided in the body 80 of the engraving device, and thereby force the spindle 8| of the cutter 82 into a position to operate upon the plate. The rotation of this spindle is effected by means of an air turbine, the air being admitted by way of the ducts 83 and caused to pass through the jet 84 onto the blades 85 of the turbine rotor to which the cutter element is secured, the cutter element being continuously maintained in rotation by the flow of air and being forced into the position to operate on the plate only when current passes through the winding 16.

The whole of the moving parts of the cutter device and its housing is located in a recess 86, as will be seen, in the body 80 and the body 80 is constrained as a whole towards the face of the plate being operated upon by means of a spring 81.

Figure 4, as above stated, is a fragmentary view of the essential parts of an alternative construction which in many respects resembles the construction previously described in that, for instance. the cutter and its operating mechanism i are of like construction and like parts in this figure are indicated by the like references employed in the description of the construction illustrated generally by Figures 1 to 3.

In the case of the construction shown in Figure 4, however, the arrangement of the cutter device and the scanning device is such as to secure the operation of the cutter on the face of the plate opposite to that on which the etched image is formed, and in this case there is no necessity for the provision of delay mechanism such as is employed in the first construction.

Generally, the scanning device corresponds with the construction of the scanning device already described, in that it comprises a ball headed pin 88 the head 33 of which is engaged in a member 99 furnished with a plane surface 9! contacting with the surface of the plate and a spherical surface 92 engaging in a spherically surfaced recess 93 in the arm 94 which is pivoted on the shaft 95 and bears by its own weight against the upper surface of the plate.

The stem of the pin bears against a pad 96 on the arm 91 pivoted on the pin 98 and one end of the arm is furnished with a contact member 99 adapted to co-operate with the contact I00 on the'stud IilI which is arranged to permit of the adjustment of the position of this contact.

When the contacts are brought together by the pin entering a recess on the face of the plate, the circuit including the winding E6 of the cutter actuating element and the battery I82 will be completed.

Thus, the winding will be energised and the cutter will be brought into operation upon the rear surface of the plate the arrangement shown being designed for the purpose of underlaying.

Figures 5 and 6 illustrate a construction in which the engraving is effected upon a cylinder or upon a sheet or plate mounted upon a cylinder.

In this construction the cylinder IE3 is mounted upon a splined shaft I04 and is furnished externally with a screw-threaded extension IElE engaging an internally screw-threaded aperture in the standard Hi6, the extension in question being tubular and the splined shaft extending through it and being adjacent to one end-rigidly mounted in the standard I01.

On the shaft there is provided a worm wheel I08 driven by the worm IE9 of themotor H0 and further on the spindle there is secured a spur wheel -'III engaging a "spur wheel II2 on the shaft I I 3' whichis rotatably mounted in bearings I I14. -On-the shaft there is secured a disc H5 in holes in' which are arranged a plurality ;of "pinsllfi' adapted 'by the electro-magnet II! 'to be caused to project through one side of the disc when the' electro-magnet is energised, such 'energising of the magnet being effected by the scanning device indicated by the reference H8, which is secured adjacent to the engraving element II9 the scanning device and engraving element being generally of the character described-in connection with the preceding examples. 1 V

The scanning device operates to establish or interrupt the connection between the battery I20 andthe electro-magnet above referred to, and whensuch connection is established the magnet will be energised andwill, when it is energised, cause one or more pins to project beyond the right-hand face-of the disc and thus be brought into a position whereby they will be moved over a cam shaped surface of the pin I2I whereby -the pin will be moved in opposition to the spring I22.to cause-the cutter to operate upon the cylinderor the plate secured about the same.

In order to cause the replacement of the pins after-they have served this purpose, a cam surface finger I23 is provided.

Iiclaimli a t I 1. Apparatus for producing engraved surfaces .comprisingmeans' whereby the etched plate is supported in association with means for securing relative motion between the plate and a mechanical scanning device including a feeler adapted, by its movement in accordance with the local variations in level of the surface of the plate, to control the relative position of electrical contacts arranged in a circuit including a source of supply. of current and an electro-magnet device, a disc/to which rotary motion at an appropriate speed is imparted, a plurality of pins slidably secured in the disc and adapted to be displaced by the electro-magnet device, a rotary cutting tool associated with means adapted to retain it normally out of contact with the etched plate and means associated with the rotary cutting tool adapted to co-operate with the pins in displacing the cutting tool into contact with the surface of the plate and means for re-setting the displaced pins after they have performed their function in relation to the cutting tool.

2. Apparatus for producing engraved surfaces comprising, means for supporting a plate formed with an image in relief on one surface thereof, a mechanical scanning device including a yieldingly mounted feeler adapted to be maintained in physical contact with the image, means for secm'ing relative motion between the plate and the scanning device whereby yielding movement of the feeler is efiected in accordance with local variations in the level of the surface of the image, a cutting tool adapted to engage the surface of the plate carrying said image and to operate upon successive areas of the plate, means operably responsive to movement of the feeler for effecting control of the operation of the cutting tool upon the said successive areas in accordance with movement imparted to the feeler by the said local variations in level of the surface of the image, and time delay means associated with said control means.

3. Apparatus for producing engraved surfaces comprising in combination, means for supporting a plate carrying an image in relief, a feeler, yieldable means urging said feeler into engagement with the image carried by the plate, means for securing relative motion between the plate and the feeler, a cutting tool arranged adjacent said feeler and adapted to engage the surface of the image, means responsive to the movement of said feeler for controlling the engagement of the cutting tool with the plate, and means for delaying the operation of said control means so that the cutting tool will operate upon a portion of the plate previously engaged by the ieeler.

JOHN WILLEY DALTON.

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