US2067867A

US2067867A - Engraving machinery

Info

Publication number: US2067867A
Application number: US77948A
Authority: US
Inventors: Taylor William
Original assignee: Kapella Ltd
Current assignee: Kapella Ltd
Priority date: 1935-04-27
Filing date: 1936-05-05
Publication date: 1937-01-12
Anticipated expiration: 1954-01-12
Also published as: GB455656A

Description

Jan. l2, 1937. W, TAYLOR ENGRAVING MACHINERY Filed May 5, 1936 3 Sheets-Sheet 2 Irwell tol wal/4 ttony.

Jan. 12, 1937.v w. T .AYLR

FJKERIAIIM: MACHINERY Filed May 5. 193e 3 Sheets-Sheet 3 v I nuez-1to1" FWB. as E7 Patented dan. l2, i937 ENGRAVING MACHINERY William Taylor,

Kapella Limited, Lei ration of England Leicester, England, assigner to cester, England, a corpo- Application May 5, 1936, Serial No. 77,948 in Great Britain April 27, 1935 9 Claims.

This invention relates to engraving machin-es embodying a pantograph linkage to control the relative motion of the engraving tool and the work in harmony with the motion of a tracer about a model or copy; and it has for its object to provide improved and more useful construc tions of such machines, and particularly to providez-a more rigid support and control of the cutter; improved means for driving' at its end remote from the cutter a rotary cutter spindle carried by the pantograph; improved means by which the plane of the copyholder is brought nearer to the plane of the work; a primary pantograph, preferably fixed, and a secondary pantograph, preferably adjustable, and adapted to work in series with the primary pantograph so as to extend or reduce its range of proportion; means by which, with. a pantograph system having a substantial ratio of reduction and a substantial range of motion for the cutter, th-e copy may be brought near to the work; means by which, with the main axis of the primary pantograph system intermediate between the cutter and the tracer, the copy and the work have the same orientation; improved means by which such a machine may be adapted for yengraving in three dimensions from a copy either the same size as, or of a size different from that of, the work; improved cutterfeeding means, and to provide a machine unit comprising a frame adapted to carry a copyholder and a pantograph or pantographs, a rotary cutter spindle and means for driving it, the entire unit being adapted ier attachment in alignment interchangeably with various forms of work-holding devices.

I will describe my invention with reference to the accompanying drawings in which:-

Fig. 1 represents in side elevation, and Fig. 2 in plan, an engraving machine embodying the invention. Fig. 3 shows in side elevation, and Fig. i in plan, an arrangement of the cutter spindle and its feeding mechanism. Fig. 5 shows, in section, the bearings on one of the principal axes cf the primary pantograph. Fig. 6 shows, in plan, a means of attachment of a formercarrying arm. Fig. 7 shows in section, and Fig. 8 in plan, a mechanism for advancing and retracting the tracer in successive predetermined steps.

The machine comprises a base l having in its upper surface a longitudinal T-slot 2, beneath it a transverse T-slot 3, and at one end a transverse T-slot ll. Attached by bolts to the T-slot 2 is a copyholder 5 having a tongue 6 which fits the T-slot by which means the copyholder may be ad- (Cl. SiO-13.1)

justably s-et in various positions on the base without changing its orientation. The copyholder includes means such as the series of tapped holes i8 or T-slots, by which a copy or model may be secured to it. By means of the transverse T-slot 2, a variety of workholding devices may be attached interchangeably to the base l, and the said slot being in a plane parallel to the upper face of the base i, and being at right angles to the T-slot 2, such workholding devices, which are provided with tongues 68, are automatically aligned with the T-slot 2 and thereby with the copyholder 5. The workholder shown is an angle plate $9 with T-slots 'lil in its upper face at right angles to the T-slot 2, and by which an object may be secured by means of bolts. Other workholding devices are too well known to need specific description. Similarly, the T-slot ii,Y

which is in a plane parallel to the upper surface of the base l and is at right angles to the T-slot 2, may be used to attach the machine unit by its base l to other forms of workholder such as a column il, the upper end of which is indicated by dottedr lines. Columns of this kind are well known in machine tools, and may comprise vertical guideways 'l2 on which a slide rest or other workholding device may be mounted for vertical movement. The .column is provided with a tongue i3 adapted to engage the T-slot 3 and the base E, so as to align the machine unit with such elements as the slideway 'i2 on the column.

Attached to the base is a support 'l with an integral column 8 on a vertical axis which I term the main axis. Mounted on the column 8, on bearings at 9 and it! spaced 'well apart, (preferably on ball or roller bearings not shown in detail) is a swivel member il which supports, in an axis l2, a pair of bearings I3, ifi, spaced Well apart. A carriage member l5, carried by said bearings, is adapted to carry in an axis l5 a cutter spindle i9 mounted in bearings in a cylindrical quill il. The axis i2 (which I term the rst axis) is parallel to and in one plane with the main axis at 8, and parallel to and in one plane with the cutter spindle axis i6. As illustrative ci what is meant by the expression spaced well apart attention is called to the fact that, in the case of the carriage member l5, the eiective centres of the bearings for example i3, lll are at a distance from one another at least equal to the distance between the axes l2 and l, and similarly, in the case of the swivel member ll, that the corresponding distance between the centres of the bearings on the column 8 is at least equal to the distance between the axes 8 and I2. The importance of such proportions is that they go to secure rigid support and control of the cutter spindle I9. As obviously a single long bearing is the equivalent of two bearings spaced well apart, and the latter acting together, in effect, constitute a long bearing, the term long bearing is used in the claims to imply either a single long bearing or two separate spaced bearings.

The swivel member il carries in an axis 25, at

a substantial distance from of bearings whereon an arm 2l is pivotally supported, and the axes 21 and I2 are all in one plane parallel to one another. The arm 2l carries in an axis at 22, interchangeably, either a joint pin 23 or a tracer 24, and in an axis 25 is pivotally connected to a link 23, the

axes

25, 29 and 22 being all in one plane and parallel to one another. The link 26 is pivotally connected at an axis 21 to a lug 2B on the lower end of the carriage member I5, the axes 21, I6 and I2 of the carriage member being all in one plane and parallel to one another. The distances between the

axes

25 and 21, and between the axes I2 and 20, are equal, and similarly, those between the

axes

20 and 25, and the axes l2 and 21, are equal.

one another, a pair The axes I5, 8 and 22 are arranged in one plane and remain in one plane in all working of the members which graph.

In the example illustrated, the ratio of the pantograph is fixed at 4 to 1, but may be adjustable in known manner, for example by moving the axis 8 further from l2, and by moving the axis 22 nearer to 29. It is, of course, not essential but it is convenient that the link 23 is placed on that side of the swivel member 'II remote from the tracer axis 22. Means such as a pulley 29 at the upper end of the cutter spindle I9 are provided for driving the spindle by any convenient means which may, for example, include a pulley 33 attached to an electro motor, a belt 3l, the motor being desirably carried from the swivel member II with its axis in the axis I2 of the carriage member, so that the tightness of, the belt is unaffected by the motion of the pantograph. The quill I1 is slidably mounted for longitudinal motion in the carriage member I5, and may be fed downwards so that a cutter carried in the lower end of the spindle I9 may be fed into the object to be engraved or withdrawn therefrom by the following means-A crosshead 32 fixed to the quill I1 is urged upwards by

springs

33, 33 against

collars

34, 34 on

rods

35, 35, around which the springs are placed and which are fixed in a second crosshead 35. Lugs 31, 38 on the carriage member I5 are drilled to receive one of the rods 35 so as to prevent rotation of the crosshead 33 round the axis I5 of the cutter spindle.

The crosshead 36 has a downwardly projecting tubular sleeve 39 passing through a hole in the lug 31, and mounted rotatably within said hole is a tube 40 with a flange 4I, by which it may be manually turned. The tube 4U has a longitudinal internal keyway 42. Mounted rotatably on the crosshead 33 in the axis of the cutter spindle I9 is a nut 43 which may be turned by hand and which, to facilitate such turning, contains a ball-thrust bearing 44, and mounted within the nut is a screw having at its lower end a head 43 from which a key 41 projects radially and, according to the rotational position of the flange 4I, either abuts beneath said tube or is free to move into the keyway 42. 1n order to use positions thus constitute a pantothe feed nut 43 to move the cutter spindle I9 up or down, the tube 49 is turned so that the key 41 abuts against its under-side, being urged thereto by the

springs

33, 33 which tend to lift the crosshead 33 and the nut 43 and thus to put the screw 45 in tension, the screw 45 being then, in effect, anchored to the lug 31 of the carriage member l5. Turning the feed-nut 43 moves the crosshead 33, the quill I1 and the spindle i9 up or down in relation to the carriage member I5. The nut 43 may be graduated and a iiducial mark provided on the crosshead 35 so that the feeding movement of the quill l1 may be measured.

In order that, when required, the object may be engraved in three dimensions by giving to the cutter spindle I9 an up-and-down motion controlled by a former and follower, the column 8 may be extended upwards so as to carry an arm 48 adapted to support, above the cutter spindle, a former such as 43 of any desired form, the counterpart of. that to be formed on the object. The arm may be aligned with the column 3 by means of a seating 50 against which the arm bears on the column, a claw 5I and a wedge-bolt 5?. which definitely locate the arm on the column but permit its longitudinal adjustment thereon. The arm may be provided'with a tongue 53 adapted to iit in a groove in the former 49, and by these means the orientation of the former may be iixed in relation to the workholding device. Attached to the upper end of the feed screw 45 is a follower 54 which, as shown, has a hemi- Spherical form but may have any convenient form, and this follower is caused to follow the contours of the former 49 and thereby to control the upanddown motion of the spindle I9 by the following meansz-The flange 4I is turned so that the key 41 on the head 45 of the feed screw 45 is free to enter the longitudinal keyway 42 in the tube 45. A spring 55 housed within the tubular sleeve 39 of the crosshead 36 urges the feed screw 45 downwards so as to keep the feed nut 43 seated against the crosshead. The entire unit, comprising the spindle I9, its quill I1, the

crossheads

32 and 35, and the follower 54, are then lifted automatically by the

springs

33, 33 so that the follower follows the surface of the former 49; but the feed nut 43 may be used to adjustably advance or retract the cutter spinr dle I9 relatively to the follower 54 so as to adjust the depth of cutting in the object.

In order to reduce the friction between the tubular sleeve 33 and its bearing in the lug 31, due to lateral pressure on the follower 54 when it is operating on a steeply inclined surface on the former 49, a number of balls 55 loosely housed in a cylindrical cage 51 are accommodated in an annular space between the cylindrical exterior of the sleeve 39 and the cylindrical interior of the tube 49, so as to form therebetween a roller bearing for longitudinal motion.

An alternative means of engraving in three dimensions is provided by the following:-The tube 45 is turned in the lug 31 so that the key 41 of the feed screw 45 abuts against the underside .of the flange 4l. A peripheral edge of the feed nut 43 is provided with a number of equidistant notches 53 adapted to be engaged by the end of a Spring bolt 53 so that, by turning the feed nut for example one notch at a time, the cutter spindle i9 may be advanced or retracted in the carriage member i5 by successive equal amounts, depending on the pitch of the screw 45 and the number of` notches 58.

Mounted interchangeably in place of the joint pin 23, the tracer 24 shown in Fig. 7 is placed, the tracer being screw-threaded to engage a hole tapped in a plate 60 which is removably attached to the pantograph arm ZI. The tracer 24 has on its lower end a follower 6I which, as shown, has hemispherical form but may have any convenient form preferably corresponding to that of the cutter; and the upper end of the tracer 24 is provided with a head 62 having in its peripheral edge a number of equidistant notches 63 adapted to be engaged by the spring plunger 64 carried by an arm from the lug 60. The pitch o-f the screw on the tracer and the number of notches 63 in the head 62 are so correlated with those of the cutter feed-nut 43 that, by turning both the feed nut 43 and the tracer screw head 62, one notch at a time, the tracer is moved longitudinally an amount, greater than the corresponding movement of the cutter spindle, in the ratio of reduction at which the primary pantograph operates. By these means an object such as a mould may be engraved in three dimensions by xing on the copyholder 5 a model of the engraving to be produced, enlarged in the ratio at which the pantograph operates, and the engraving is done by taking a series of cuts in parallel planes distant from one another, as determined by the successive advances of the feed screw 45, and in each plane the follower 6I is traversed in a corresponding plane along the contours of the model in that plane.

It is convenient, when using the machine to engrave for example lettering from a copy consisting of engraved lines, that the pantograph arm 2I should be free for small elastic motion in the plane including the

axes

26 and 22, and for this purpose the arm 2| is made suiciently thin and flexible, as seen in the elevation Fig. l, but broad, as seen in the plan Fig. 2; but when engraving in three dimensions in the above manner, it is desirable that the arm .should be rigidly held against such elastic motion, and for this purpose a tie-rod 65, attached to the arm 2l toward its free end, is slidably housed in a hole 66 toward the top bearing which joins-the arm 2| to the swivel member II, and may be locked therein by the eye-bolt 61 so as to resist elastic bending of the arm 2I.

In an engraving machine having a considerable ratio of reduction, that is, a considerable ratio of the distance between the axis 22 and the axis 8, in Fig. 2, to the distance from the axis to the cutter' axis I6, and especially where it is desired to have a. considerable range of motion for the cutter I6, the tracer 22 is so remote from the object to be engraved that it is diiicult to see, and sometimes difcult even to reach, the tracer and the cutter feed mechanism at the same time. i In one type of engraving machine described by me, I encountered the difficulty of supporting the cutter spindle in a carriage member such as I5, pivotally supported in turn on a swivel member which in turn was` pivotally supported as on the axis 3 from the machine base, and I mounted a complete and independent pantograph of thin links above the carriage member I5 and connected thereto in the axisof the cutter spindle at I 6.

This, while making it possible to bring the main axis of the pantograph near to the axis I6 without physical interference, placed the pantograph at a considerable elevation above the surface of the object where it was at a disadvantage in rigidly controlling the movement of the cutter at the lower end of the carriage member. It

also made it diiicult to drive the cutter spindle from its Lipper end, and dinicult to attach the follower 54 near to, and in the axis of, the cutter spindle.

By the present invention these diiiiculties are overcome. The pantograph arm 2l may be placed low down on the swivel member II and relatively near to the plane in which the cutter operates. The spindle I9 is free to be driven at its upper end, and there is no pantograph to intervene and to require lateral space between the spindle and the follower 54; but the pantograph cannot have a large ratio of reduction and a large range of motion for the cutter, and it would necessitate, as hitherto, sacrificing the massiveness and rigidity of the swivel member, the carriage member I5, the spindle bearings and the supporting bearings on the main axis 8. Therefore, according to this invention, I embody the carriage and swivel members in a pantograph linkage having only a moderate ratio of reduction, and I use a second pantograph, which I term the secondary pantograph, placed tandem or in series with the primary pantograph, and arranged so that it either increases or reduces the ratio of the primary pantograph. A form of such secondary pantograph is shown in Figs. 1 and 2, in which a bracket I4, bolted to the base by the T-slot 2, carries in bearings l5, 'I6 on anvaxis TI, which is the main axis of the secondary panto graph, a supporting link 'I8 at the ends of which, on axes I9 and 80 respectively, are pivoted two bars 8l, 82 adapted to receive

sliders

83, 84. The sliders arey pivotally connected at 35, y86 to a cross-link 8l adapted to receive a slider 88 which can bei pivoted by the joint pin in the axis 22 to the arm 2|. In the axis 89 atracer or follower 99 is carried above the copyholder 5. The links 78, SI, 82 and 81 form a pantograph linkage in which the axes Tl, 22 and 89 are at all times in one plane and parallel to one another, and the ratio of the distances between the axes TI and 39, and 'Il and 22, may be varied by adjustably moving the

sliders

83, 84 and 88 along their respective bars or links.

Although I have shown a secondary pantograph adapted for reduction, it will be readily understood that, by transposing its long and short arms, pivoting the long arm by its point 89 to the free end 22 of the primary pantograph arm 2l, pivoting the slider 86 to the bracket 'I4 fixed on the base, and putting the style in the axis 88 of the bar 18, such a pantograph would be adapted for enlargement and might, in eiect, reduce the ratio of the primary pantograph to zero.

It is an advantage, in pantograph engraving machines, to have the main axis 8 intermediate between the tracer axis 22 and the cutter axis I6 so that the cutter may overhang the frame of the machine to enable the machine to accommodate large objects, but this arrangement entails the disadvantage that, in using the primary pantograph alone, the copy must be placed in the position reversed with respect to the object to be engraved, for example a copy letter would be placed upsidedown in order to engrave the letter right way up. By the use of a secondary pantograph, however, according to this invention, but by moving the supporting link I8 to the other side of the link 81, as shown by the dotted lines in Fig. 2, so that the ixed axis 'I'I by which the secondary pantograph is supported is intermediate between the axis of the tracer 89 and the axis 22 by which the secondary pantograph is connected to the arm 2I of the primary panto- 4 graph, such reversal of orientation of the copy and object is corrected and both have the same orientation.

By arranging the secondary pantograph so that its tracer in the axis 89 is intermediate between the axes 8 and 22 of the primary pantograph, the copyholder 5 is brought relatively near to the cutter spindle I9 notwithstanding that the combined ratio of the pantographs may be a large one.

For convenience, the term tracer is used in the claims as indicating no-t only the tracer 90 of the secondary pantograph but also that point of the primary pantograph at which the tracer would be .attached if there was no secondary pantograph coupled thereto. Similarly, the term cutter is used to indicate that point of the secondary pantograph at which the cutter would be attached if there was no primary pantograph.

In pantograph engraving machines in which hitherto the pantograph has been mounted above the swivel and carriage members supporting the cutter spindle, it has been necessary to drive the cutter spindle by means of a pulley fixed at the lower end thereof, and to employ elaborate devices of guide pulleys with stay rods to lead a driving belt to the cutter spindle pulley and to accommodate the lateral motion of the cutter spindle without changing the tension of the belt. By means of the present invention, which enables me to drive the spindle from its upper end, it becomes practicable to mount an electro motor onthe swivel member l I with its .axis in line with the pivot axis I2 of the carriage member, and, from a pulley on the motor spindle, to drive directly the cutter spindle pulley 29.

What is claimed is:

l. In an engraving machine and the like, a primary pantograph linkage comprising an arm and a junction pivot carried thereby, a support, a swivel member pivotally mounted on said support on bearings spaced well apart, and pivotally carrying said arm, a carriage member pivotally carried by the swivel member on bearings spaced well apart and carrying a rotary cutter spindle, and a link connecting the carriage member and the arm, the axes of the junction pivot, the support and the cutter spindle being at all times parallel to one another and in one plane, and a secondary pantograph comprising an arm and a tracer carried thereby, a swivel member pivotally mounted on a support and pivotally carrying said arm, a junction member pivotally joined to the swivel member and pivotally con* nected by the junction pivot to the primary pantograph, and a link connecting the junction member and the arm, the axes of the junction pivot, the sup-port and the tracer being at all times parallel to one another and in one plane.

2. In an engraving machine having primary and secondary pantographs as claimed in claim 1, arranging said pantographs so that the orbit of motion of the tracer of the secondary pantograph is nearer to the cutter spindle axis than is the orbit of the junction pivot between the two pantographs.

3. In an engraving machine and the like, a pantograph linkage comprising an arm and a tracer carried thereby, a support, a swivel member pivotally mounted on said support on bearingsv spaced well apart, and pivotally carrying said arm, a carriage member pivotally carried by the swivel member on bearings spaced well apart and carrying a rotary cutter spindle, and a link connecting the carriage member and the arm, the arm being restrained from motion in any axial plane of a common pivot of the arm and the swivel member, and the tracer and the cutter spindle being adapted for longitudinal movement in the arm and the carriage member respectively, and havingV means such as screws to move them and means such as catch discs by which they may be moved in successive increments corresponding to the ratio of the pantograph.

4. In an engraving machine, a fixed support, a frame mounted on said support to swing about a fixed axis, a second frame mounted on the first irame to swing about an axis parallel to the first axis, a cutter spindle rotatably mounted on the second frame for rotation about an axis parallel to the other axes, the bearings of the first frame with respect to the xed support and of the second frame with respect to both the rst frame and cutter spindle all being long, whereby the axis of the latter is maintained in exact Yparallelism with respect to the first axis, a primary pantograph for controlling the lateral movementsv of the cutter spindle and the supporting means therefor, and a secondary pantograph connected to the primary pantograph for varying the reduction ratio of the rst pantograph.

5. An engraving machine as in claim 4, in which the two frames form parts of two links of the primary pantograph, the rst mentioned axis being the fixed axis of such pantograph.

6. In an engraving machine, a cutter, a primary pantograph for controlling the lateral movements of said cutter, a fixed pivot therefor, said pantograph having said pivot in the middle of the series, cutter-piVot-tracen and a secondary pantograph wholly on the tracer side of the fixed pivot of said primary pantograph and having its cutter connected to the tracer of the primary pantograph.

'7. In an engraving machine, a cutter, a primary pantograph for controlling the lateral movments of said cutter, a xed pivot therefor, said pantograph having said pivot in the middle of the series, cutterpivot-tracer, and a secondary pantograph having its cutter connected to the tracer of the primary pantograph and its tracer between the xed pivots of the two pantographs.

8. In an engraving machine, a cutter, a primary pantograph for controlling the lateral movements of said cutter, a secondary pantograph having its cutter connected to the tracer of the primary pantograph and the tracer of the secondary panograph intermediate the fixed pivots of the two pantographs.

9. In an engraving machine, a cutter, a primary pantograph for controlling the lateral movements of said cutter, a xed pivot therefor, said pantograph having said pivot in the middle of the series, cutter-pivot--tracer, and a secondary pantograph having its fixed pivot in the middle of the series, cutter--pivot-tracer, and having its cutter connected to the tracer of the primary pantograph.

WILLIAM TAYLOR.