US 2874479 A
Description (OCR text may contain errors)
Feb. 24, 1959 M. FARSER ENGRAVING MACHINE STYLUS INDEX Filed. July 15, 1955 PHASE SHIFTER ENGRAVER TO GEN E k ATORl ATTORNEY I N VENTOR.
ENGRAVIVG MACHINE STYLUS INDEX Monroe Farher, Jericho, N. Y., assignor to Fairchild Camera and Instrument Corporation, a corporation of Delaware Application July 15, 1955, Serial No. 522,217
Claims. (Cl. 33-185) This invention relates .to automatic engraving machines of the type used for the production of relief printing plates automatically from photographic or other originals. More particularly, the invention relates to an indexing or precision indicating mechanism for accurately positioning the point of the engraving stylus with respect to the surface which is to be engraved.
An automatic engraving machine of the type. to which this invention is applicable is shown and described in U. S. Reissue Patent -Re. 23,914 to Boyajean, dated December 21, 1954 and owned by the assignee of the present invention. As disclosed in that patent the. apparatus comprises a pair of cylinders mounted for synchronous rotation upon a common shaft, one of the cylinders being arranged to carry the original copy in position for helical scanning by photoelectric means, and the other cylinder carrying a flexible plastic plate upon which a representation of the original is engraved in a helical path by the action of an electromagnetically driven engraving tool controlled by the output of the photoelectric scanner.
A critical feature of such an apparatus lies in the necessity for very accurate positioning of the point of the engraving stylus with reference to its distance from the surface of the plate which is being engraved. In the past, this has usually been done by making a trial cut on the plate, the result being observed visually, and any necessary adjustments being made accordingly. While such a procedure isreasonably effective, it requires theme of a time-consuming cut and try method for obtaining the proper engraving stylus setting. v To facilitate the making and maintaining of the engraving stylus adjustment and for ,other purposes, the engraving machine of the prior patent was provided with an advance shoe on the stylus motor,- adapted to contact and ride upon the surface of the plate to be engraved, at a position adjacent to and in advance (with respect to the sheet travel direction) of the location of the stylus itself, so that the position of the stylus driving motor with reference to the sheet to be engraved could be established accurately. However, this arrangement still requires some way of locating the position of the point of the stylus accurately with respect to the advance shoe which rides'upon the sheet to be engraved, to establish the desired cutting or engraving depth for a given driving signal amplitude.
It is therefore a principal object of this invention'to provide a means for establishing, prior to the making of an engraving, the desired precise relationship between the tip. of the engraving stylus and a predetermined reference plane or line. Preferably, the arrangement of the present invention is such that the achievement of this precise relationship is obtained by optical means, by. a single operation, and obviating the necessity of repeated trials for obtaining the desired result.
, This invention is a modific ation and improvement of the indexing arrangement disclosed and claimed in my copending application Stylus Indexing Arrangement For Engraving Machine's" filed December 8, l'953j'and having Serial No. 396,955, new Patent No. 2,788,255; it may also be used in conjunction with that prior arrangement. The device disclosed in that application utilizes a physical signalling means, such as a buzzer, light or equivalent electrical signalling means to indicate when the desired stylus position or relationship is obtained.
It is a further object of this invention to provide an optical device, such as a microscope, to permit the quick and simple adjustment of the stylus to its proper position or relationship to the sheet surface to be engraved or cut,
-Another object of this invention is to provide an integral gauge and stylus indexing miscroscope for use with an engraving machine, which device may be utilized under the exact conditions under which the engraving machine is next to be operated. An additional object of the invention is to provide an optical gauge of the type mentioned above whose operation will minimize the likelihood of injury to the engraving stylus from carelessness of an operator in attempting to position the stylus.
Another object of this invention is to provide a unitary gauge and microscope stylus indexing device which will not only permit adjustment of the stylus to its proper position while at rest, but will also permit observation and extremely accurate adjustment of the extreme forward travel position of the stylus when it is being vibrated rapidly in an operative state, as by the kind of signal which it receives during actual engraving. Thus, the position of the tip can be observed when the stylus motor is responding to signals corresponding to different parts of an original from which an engraving is to be made.
It has been usual with engraving machines of this type to establish a known relationship between the tip of the stylus and the reference plane defined'by the sheet-contacting surface of the advance shoe. After this relationship has been established, a skilled operator was required to adjust the throw or travel of the stylus so that the desired depth of cut for a particular engraving job would be obtained. With the present invention, however, the desired position of the stylus at rest, and the extreme forward position of the stylus while in an operative and oscillatory motion, may also be observed, gauged and adjusted by means of extremely accurate indicia within the microscope portions of the device; this can'readily be accomplished even by personsrelatively unskilled in the engraving art.
The above and other objects and advantages of the invention will be understood by reference to the following specification and to the accompanying drawings showing a preferred and exemplary embodiment of the invention:
Fig. 1 is a side view, partially in vertical section, of the stylus gauge and index together with sufficient of the parts of a typical engraving machine for an understanding of the invention,
Fig. 2. is a front elevational view of the gauge and indexing element shown in Fig. 1,
Fig. 3 is a representation of the stylus as it appears when viewed through the microscope portion of the indexing and gauge apparatus,
Fig. 4 is a similar representation of the stylus in mo Boyajean patent for details of parts not essential toan understanding of the present invention.
Referring particularly to Fig. 1, it is seen that the reference numeral designates the main shaft of the engraving machine,-carryinga cylinder 12 upon which is secured a plate or sheet 14 which is to be engraved. The sheet or plate 14 may be of plastic or like material, or metal, depending upon the process employed.
The engraving stylus, and its motor and associated parts, are carried lengthwise of the cylinder 12, as upon guide rods paralleling shaft ll one such guide rod being indicated by the reference numeral '16. Although the stylus arrangement and motor as such form no part of this invention and are described and illustrated in detail in my copending patent application above, a brief descript-ion of these parts is now given to enable a better understanding of the relative cooperation .between the optical gauge and the stylus mechanism.
"The sliding carriage for the stylus drive'mechanism is indicated by reference numeral 18, and a stylus motor base is shown pivoted at 22 upon the carriage 18. The entire stylus motor and stylus may be retracted away from the cylinder 12 by pivoting upon pivot 22. 'During the actual engraving operation the stylus motor assembly is held in the position shown in Fig. l by an electromagnet 24. The stylus motor itself, designated generally by the reference numeral 26, comprises a magnetic yoke structure 28 and drive coils 30 and 32. An armature 34 is pivotally mounted as by a torsion bar 36, such that energizaticn of the coils 3t) and 32 will cause the armature to pivot and drive the rod 38 toward and away from the axis of cylinder 12. The rod 38 terminates in a stylus chuck 44), in which is held the stylus 42. Surrounding the end of the stylus 42 is an electrical heating coil independently mounted to heat the stylus without interfering with its axial motion through the coil. The heating coil, of course, is not required if the process used is a cold cutting or similar engraving process.
Reference was made previously to an advance shoe, a locating means disposed to ride upon the surface of the plate 14 just in advance of the stylus. This is shown in Fig. l as a cylindrical rod 44 made of a very hard and smooth material, as for example, sapphire. This shoe 44 is held in a mounting frame 46 carried by a hat hairpin spring 48 secured at its lower end to a frame structure 50 which contains the stylus motor 26.
In order to permit adjustment of the advance shoe 44 with respect to the at rest or neutral position of the stylus 42, a push rod 52 is threadedly carried 'by "the frame-5t and its forward end engages the spring48 and urges it against its spring tension to position the forward surface of the advance shoe 44 in a precisely defined position. Movement of the entire stylus and motor assembly toward and away from the cylinder 12 is accomplished by means of a screw 54 which threadedly engages a bracket 56 fixed upon the plate 20. Since this adjustment is to regulate the neutral or at rest position of the stylus point relative to the cylinder for a given advance shoe setting, screw 54 does not have a solid connection to the stylus motor 26, but rather acts through a spring indicated by reference numeral 57. Adjusting knobsfifi and 6d are provided for the shafts 52 and 54.
The gauging element. 62 of Fig. 1v is formed. of a .suitable material such as metal, and is in the form of a block .or the like whose under-surface 64 is curved cy1indrically to conform to the sheet 14- carried by thecylinder 12. ltsfront surface, or that opposite its surface 6.4, is also preferablycurved on an arc concentric to that of the rear surface. The front surface 65 of thegauge has a centrally located window 66' opening into a pocket in the interior of the gauge. Extending from the block 64 is an elongated member 63 terminating at its upper end iiTa broadened support portion 7t Rigidly mounted on the broadened support portion 70 is a microscope 72 having the usual. eyepiece 74, objective lens 76'. and focusass/nave ing knob arrangement 78. Contained within the micros'copeandmounted therein in a manner well known in that art is a target reticle 80 shown in Fig. 3. The reticle 80 contains a number (one or more) of cross-hairs 82, S4, 86 and 88; if more than one, these are located at spaced measured intervals.
Since the advance shoe 44 'is disposed, as illustrated in Fig. 1, behind the position of the stylus 42, relative to the direction of travel lengthwise of the sheet, the advance shoe will ride upon a marginal surface portion of the gauge .62 (away from window 66) when the latter is in the position shown. The microscope 72 is so situated on its support 70, and the reticle 80 so positioned within the microscope, that when the stylus pipis seen through the microscope to touch the cross hairline 82, for example with the stylus dc-energized, the point of the stylus 42 will be extended to a position in the plane of the front surface of the advance shoe 44. The forward surface 65 of gauge 62 .will generally also be visible, .but is omitted from .Fig. :3 fon'clarity.
The contacting surface of the advanceshoe' 44' will be 'adjusted'to .be tangent to thefront surface .65 :of gauge 62, .justias it Wouldbe tangent to the sheet 14 during the making of 'an'actual engraving.
Mounted on the support portion 70 .of the gauge 62 is a light source 90 which is directed downwardly as shown in Fig. 1 in order to illuminate the tip of stylus 42. For a purpose to be described, the light source 90 may be stroboscopic in nature, such as a flash lamp emitting brief flashes, so that when the stylus motor 26 is energized, the stylus may be observed in any desired portion of its work cycle by adjusting the phase of the strobcscopic lightsource relative to the stylus oscillations. The light may be energized from the engraver tone source to ensure inherent automatic synchronization with stylus travel.
To permit the gauge to be used when shaft 10 and cylinder 12 are actually rotating, as they do during an actual engraving, the under surface of gauge 62 may be provided with roller bearings 92 defining the contact plane between gauge and cylinder or sheet. The entire gauge may be held in place by hand, or it may be rested or supported in removable fashion upon the carriage 20 or other part of the machine. a
With the parts adjusted so that the advance shoe 44 just touches the forward surface of gauge 62, andthe stylus motor 'de-energized, the operator can readily ad just shaft 54 until the advance shoe 44 touches the surface 'of the gauge 62, and bymanipulat'ing shaft 52 the positionof the entire stylus motor'26 will be moved until the tip'of'stylus42appears to'touch one of the cross'lines for exampleline '82 in Fig. 3. If the entire gauge is now removcd,.knob 60 can be rotated to bring the advance shoe into "contact with the plastic 14, and this isaccomplished. without disturbing the alignment between the advance shoe and the stylus. Hence, the stylus tip will necessarily be in the desired position with respect to the plastic.
Since the dcpthto which the stylus penetrates the sheet to be engraved depends on the tones of the original copy, it is desirable to determine the depth of penetration or extent of forward travel of thestylus under certain conditions. To enable this to be done while thegauge '62 is in position,..the iSIYlUS. motor 26 may beenergized by usuaLtone-signals'and. the stylus observedin. the microscope 72 while under'steady illumination by: the light source 90. The appearance in the microscope ofthe stylus while being energized. would be as illustrated in Fig. -4, and. the'end positions .of. travel clearly discernible. In that figure it is seen that the extent of. forward. travel or penetrationiof .the'stylus. is easily determinedsince the cross hairs 82 and 88 are at measured and known intervals. Ifthe operator desires to observe the action-of the stylus whilein any particular portion of its vibration cycle duringtoperation, it is only necessary that the light 90 be energized from the tone source and the phase control circuit properly adjusted.
The cut-out or window portion 66 of the gauge 62, lying beneath the stylus tip, permits observation of the stylus while it is being energized or vibrated by its motor 26, without any damage to the stylus or the outer surface of the gauge 62.
In the embodiment of the invention illustrated in Figs. 1 and 2 the cylinder 12 is at rest and the entire gauge is firmly positioned by allowing the weight of the stylus motor head to press the advance shoe against the gauge 62 which in turn presses against the cylinder 12. If desired, the entire gauge assembly may be placed upon the cylinder 12 after the sheet 14 is in place upon the cylinder. The gauge is of course removed prior to commencing the engraving, as stated above, and the stylus motor advanced as by knob 60 until the advance shoe 44 contacts the sheet surface firmly, which puts the stylus tip in proper position to proceed.
The stroboscopic arrangement described above, using a light source interrupted at tone frequency to illuminate the stylus, is especially intended for engraving with a cold stylus. Where, as in the Boyajean patent referred to above, the stylus is heated to the point of incandescence in order to make the engraving by burning the sheet, the stylus itself can be viewed stroboscopically by periodically interrupting the light path from the stylus to the observers eye. Such an arrangement is shown in Fig. 5, in which similar reference numerals have been used to designate the same parts as in Fig. 1. In this embodiment, the stroboscopic light source is eliminated, and the light rays from the incandescent stylus 42 are interrupted by a drum shutter 100 comprising a hollow cylinder having slots 102, and driven by a synchronous motor 104. The housing of the motor is preferably slightly rotatably held as in a clamp 106 on the base portion 70 of the gauge. For convenience in adjusting the phase of the stroboscopic interruption of the light, relative to stylus motion, the motor casing may be knurled as at 110 and a clamping screw 112 may be provided to tighten clamp 106 when the motor has been properly adjusted.
The motor is of course energized from suitably amplified tone generator output as in the previous embodiment, and the slotted shutter 100 produces very quick interruptions of the light beam because the slots on opposite sides of drum will be traveling in opposite directions with respect to the optical axis through the shutter. However, other types of interrupters, such as rotary shutters or even a light valve of the Kerr cell type or the like may be used. The shutter or valve could equally well be incorporated into body tube of the microscope 72.
It is to be remembered that the stroboscopic feature is needed only if the stylus is to be gauged while it is in motion. If the stylus is operated without a carrier frequency supplied from the tone generator, the stroboscopic method is not required. In any event, stroboscopic observation of an incandescent stylus can be accomplished readily without the use of any auxiliary light source.
It will be seen that there have been provided ways and means for accomplishing all of the objects of invention, but it is to be understood that the specific arrangements and devices described are given for purposes of illustration and not of limitation. Various modifications of the inventive concept will occur to those skilled in the art, and it is intended to claim all such modifications as fall within the spirit of the invention as defined in the follow ing claims.
What is claimed is:
1. In automatic engraving apparatus of the type having a support adapted to carry a sheet to be engraved, an
engraving stylus mounted for movement in one direction into and out of the surface of such a sheet, means for imparting relative movement between said stylus and said sheet in the plane perpendicular to said direction, and an element adapted to contact the surface of the said sheet and adjustable in position with respect to said stylus to define the rest position of the stylus with respect to said sheet, the improvement which comprises a gauging device adapted to be removably mounted on said support, a portion of said gauging device adapted to be disposed between the surface of said support and the point of said stylus, and another portion disposed between said surface and said element, said gauging device including optical means for determining visually the rest position of said stylus with respect to said support and said element, when said element is brought into contact with said other portion of said gauge.
2. In automatic'engraving apparatus of the type having a rotatable cylinder adapted to carry a sheet to be engraved, an engraving stylus mounted for movement into the surface of such a sheet, and an element adapted to contact the surface of the said sheet and adjustable in position with respect to said stylus to define the rest position of the stylus with respect to said sheet, the improvement which comprises a gauging device adapted to be removably mounted on said cylinder, a portion of said gauging device adapted to be disposed between the surface of said cylinder and the point of said stylus, and another portion disposed between said surface and said element, said gauging device including optical means for determining visually the rest position of said stylus with respect to said cylinder and said element, when said element is brought into contact with said other portion of said gauge.
3. In an automatic engraving apparatus of the type having a support for an engravable sheet, an engraving stylus mounted for movement in a first direction into and out of the surface of such a sheet, power means for oscillating said stylus in said direction, and means for relatively moving the stylus and the support in directions laterally of the first direction, the improvement which comprises a gauging device adapted to be removably mounted on said support, a portion of said gauging device adapted to be disposed between the surface of said support and the point of said stylus, said gauging device including a microscope and reticle for determining visually the position in said first direction of said stylus with respect to said support and a sheet thereon, and stroboscopic means energized from said power means for interrupting the light passing from said stylus through said microscope.
4. Automatic engraving apparatus in accordance with claim 3, in which said stroboscopic means comprises a light source for illuminating said stylus, said light source being energized from said power source.
5. Automatic engraving apparatus in accordance with claim 3 in which said stroboscopic means comprises an interrupter in the beam from said stylus through said microscope.
References Cited in the file of this patent UNITED STATES PATENTS 804,067 Stowe Nov. 7, 1905 2,006,854 Winter July 2, 1935 2,249,121 Drescher July 15, 1941 2,534,849 Blain Dec. 19, 1950 2,575,546 Boyajean Nov. 20, 1951 FOREIGN PATENTS 553,594 Great Britain May 27, 1943