US2631669A

US2631669A - Matrix trimmer

Info

Publication number: US2631669A
Application number: US209285A
Authority: US
Inventors: Craig C Baker
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-02-03
Filing date: 1951-02-03
Publication date: 1953-03-17
Anticipated expiration: 1970-03-17

Description

March 17, 1953 c. c. BAKER MATRIX TRIMMER Filed Feb. 5 1951 5 Sheets-Sheet 1 III ll INVENTOR.

CRAIG C. BAKER ATTORNEY March 17, 1953 c. c. BAKER MATRIX TRIMMER 5 Sheets-Sheet 2 Filed Feb. 5 1951 IIIIIIIIIIIl/H INVENTOR.

CRAIG C. BAKER ATTORNEY March 17, 1953 c. c. BAKER MATRIX TRIMMER 5 Sheets-Sheet 5 Filed Feb. 5 1951 INVENTOR.

CRAIG C. BAKER Lil ATTORNEY C. C. BAKER MATRIX TRIMMER March 17, 1953 '5 Sheets-Sheet 4 Filed Feb. 5 1951 INVENTOR. CRAIG C. BAKER ATTORNEY March 17, 1953 c. c. BAKER 2,531,669

' MATRIX TRIMMER Filed Feb. 5, 1951 '5 Sheets-Sheet 5 OIOIOIQ'QIGIQI;

I INVENTOR.

CRAIG C BA KER ATTORNEY Patented Mar. 17, 1953 UNITED STATES PATENT OFFICE MATRIX TRIMMER Craig 0. Baker, Whittier, can't.

Application February a, 1951, Serial noszoaass 14 Claims. 1

This invention relates in general to the trimming of the edges of matrices 'tcbe used in the casting of stereotype plates for cylindrical newspaper presses and the likeand more particularly, relates to matrix trimming in cases where one or more color plate-matrices are required to correspond to the master matrix just as stereotype plates are required to correspond to the master plate. When such color plates are used itis absolutely necessary that these plates very accurately coincide with each other and with the master plate for, as will be readily appreciated, if one of the plates should be out of registration by the smallest fraction of an inch, the complete printed sheet will show a marred or blurred effect. In order that the corresponding stereotype plates may be so cast as to be set in absolutely accurate corresponding position on the cylindrical press it is necessary that the matrices from which they are cast have their edges trimmed exactly to correspond to each other so that the edges of the plates will then exactly correspond similarly.

An object of this invention is to provide an improved matrix trimmer in which the edges of a matrix can be trimmed accurately and easily'according to predetermined marginal spacing.

Another objectof this invention is to pro-vide an improved matrix trimmer in which three edges of the matrix, namely the three edges which will correspond to the top andbottom and ring gauge lateral sides of the printed page, can be trimmed simultaneouslyas desired.

'Another object of this invention is to provide an improved matrix trimmer in which a matrix can be trimmed to-fit closely into the casting box so that there will be no possibility of the matrix moving in the casting box during the casting operation, or of the-matrix becoming twisted or cocked as sometimes occurs when matrices are trimmed by conventional methods.

While various'means havepreviously beenemployed for trimming an edge, orfedges, of a stereotype matrix while the matrix is being held flat, nevertheless when the trimming is .per-

2 all the trimming of the matrix can be performed in a'single operation.

.A still further object of this invention is to provide *a matrix trimmer which can :be .set for trimming a plurality of corresponding matrices successively, :so that the resulting trimming of the matrices can be made to correspond very accurately.

Another object or this invention is to provide an accurate means to detect an inaccuracies in the register of the mats caused by unequal shrinkage, or by mis-register in the forms from which the mats are molded.

An additional object is to provide :a separate guide which can be used in connection with this matrix trimmer, when desired, to facilitate the setting of the trimmer for predetermined positioning of the matrix to be trimmed.

The above indicated objects and other advantages I attain by providing a matrix trimmer with means for holding the matrix in the same curved position during the trimming operation as the matrix will be caused to occupy during the subsequent casting of the stereotype plate; by providing a movable carriage on the trimmer with cutting means arranged to trim two lateral edges as the carriage moves over the matrix; by

providing additional cutting means for trimming a third edge :of the matrix simultaneously; by providing special aligning and positioning guides and means for the matrix; and, in general, by

constructing and arranging the various parts of -2, with some portions broken away for clarity;

Fig. .4 is an enlarged-fragmentary section on line 5 4 of Fig. 1.;

Fig. v5 .15 an enlarged fragmentary section on line 5- 5 oif'Fig. 1;

Fig.1; is an enlarged fragmentary section corresponding in part to Fig. 3;

Fig. 7 is a fragmentarydiagrammatic elevation taken fromi-the right ofFig. ,6 "and illustrating the operation :of the .--end rcutter in "Fig. 6;

Fig.8 iszaip'erspective'view of 'a 'special guide setting barad-apted for .nsewithmytrimmer and Fig. 9 is a fragmentary vertical section taken on line 9-9 of Fig. 1, but drawn to a larger scale, illustrating the operation of the movable supports.

My matrix trimmer comprises an outside housing or cabinet indicated in general by the reference character II) (Figs. 2 and 3). A curved or semi-cylindrical, .penforated matrix-supporting stationary plate I I (shown most clearly in Fig. 1) is mounted within the upper portion of the housing, the upper side edges of the perforated plate II being secured to horizontally-extending horizontal rib bars I2 (Fig. 2) mounted inside the housing I8.

A horizontal partition I3 (Fig. 2) forms the bottom of an upper vacuum chamber extending below the perforated plate II, and a pair of transversely-extending vertical plates I4, one of which is shown in Fig. 2, connect the respective ends of the perforated plate II with the bottom partition I3 and with the side walls of the housing and thus complete the inclosure for the vacuum chamber. An opening I5 in the partition or chamber bottom I3 is connected to an air exhaust pipe I9 leading to an air exhaust device indicated in general by the reference character I9 in Fig. 2, and which device includes a motor-driven air exhaust fan. The pipe I5 is equipped with a shut off valve 2?.) operated by the

control levers

22 and 23 extending from opposite sides of the housing I0, so that manual operation of either lever, when the air exhaust device is turned on, will cause air to be drawn from the vacuum chamber below the perforated plate II.

When a matrix is to be trimmed it is set in place on the perforated plate I! and valve 26 is then opened so that the exhaust of air in the chamber below the perforated plate i I will create vacuum suction whereby to hold the matrix firmly in place during the trimming operation. Preferably electric heating elements 2 3 (Fig. 2) are mounted on the under side of the perforated plate I I so that the matrix can be kept heated during the trimming operation. A vacuum indicator 32 is connected with the chamber in order that the operator will know that sufficient vacuum suction is being maintained to hold the matrix securely in place while the trimming is being done, and thus avoid any possibility of inadvertent moving of the matrix out of place during the trimming operation.

The housing I0 is provided with a pair of top side deck plates 28 and 2'! (Figs. 1 and 2). A plurality of focusing light assemblies or projectors, as indicated in general by the reference character 25 (Figs. 1 and 2), are adjustably mounted above the decks 26 and 2'! in any suitable manner, there being two such focusing light assemblies on each side in the particular form of my trimmer illustrated in the drawings. The purpose of each of these projectors is to project cross hairs in a small field of focused light whereby the projected cross hairs indicate an exact predetermined point at the opposite side on the matrix, and when such points have been established and the lights set, the subsequent matrices can in turn be set in exactly the same position on the perforated plate I I by bringing the corresponding points for each matrix exactly into registration with the fixed projected cross hairs of the corresponding projectors. These projectors are mounted on the trimmer housing so that their positions can be adjusted longitudinally along the housing to a slight extent by means of mounting screws 33 (Fig, 2) extending through horizontal slot in the hous- 4 in walls, and other customary adjustments are provided for each projector enabling the same to be moved on a horizontal axis and on a vertical axis for the proper positioning of the cross hairs. Such adjustments in themselves are well known and need not be here described.

A carriage indicated in general by the reference character 39 (Figs. 1, 3, 4 and 5) extending transversely across the top portion of the housing H1 and thus above the perforated plate 1 I, and movable in a direction parallel to the top side edges of the perforated plate, includes a main bottom plate is, supported at each end on a pair of wheels M, which ride on the side horizontal rib bars I2 A U-shaped cover plate 42 is mounted on the top of the bottom carriage plate 49 and a handle 40' is secured to the front wall of the cover plate 42. Horizontal guide wheels 4| (Fig. 3) are mounted respectively at the ends of the main bottom plate 40 and are adapted to bear against the adjacent side walls of the housing.

A pair of stub shafts 43 (Figs, 3, 4 and 5) extend downwardly through bearings near each end of the bottom carriage main plate iii. The upper ends of these stub shafts are mounted in suitable bearings 44 (Figs. 4 and 5) provided in the cover plate 42. A sprocket wheel 45 is keyed on each of the stub shafts 43 between the bottom main plate do and the cover plage E2 in the carriage. A rotary cutter disc 46 is keyed on the bottom end of each stub shaft 43 below the bottom of the carriage and is held in place by a suitable nut 43 threaded on the end of the stub shaft. As shown in Fig. 5, these stub shafts at are so located in the carriage 39 and with respect to the side rib bars I2 that the rotary cutter discs 46 will extend a slight distance over the inner top edge of the side rib bars I2 and thus over the parallel side edges of the curved perforated plate l I at each side.

When a matrix is placed on the perforated plate I I, and held securely against the plate I I by vacuum suction, the movement of the carriage 39 from the front to the rear of the trimmer will result in the discs 45 (which are rotated by means later described) trimming the corresponding edges of the matrix. The side rib bars I2 and the side edges of the perforated plate I i thus provide cutting bars for the cutter discs 46. Preferably, as shown in Fig. 4, the bottom carriage plate 40 slopes slightly in a forwardly direction (the axles for the forward wheels 4| being set slightly higher in the bottom plate) so that the stub shafts 43 will not be exactly vertical, but will have a very slight inclination from the vertical so that as the carriage 39 is moved from the front to the rear of the trimmer, in the forward direction indicated by the arrow at in Fig. 4, the rotary cutter discs 46 will bear on the rib plates I2 where the cutting or trimming of the matrix takes place. This not only facilitates the cutting but also enables the rotary cutter discs to a certain extent to be self -sharpening.

In order to hold the rotary cutter discs 45 against the top faces of the respective rib bars I2 as the trimmer is used, I provide a spring 4'! above the bearing for the top end of each stub shaft 43 to exert a downward pressure on the stub shaft. The spring 37 is held under compression between the top of the bearing 44 and a circular plate 58 set on the top face of the cover plate 42 of the carriage, the circular plate 48 extending over the bearing for the upper end of the stub shaft 43 and being secured in place by screws.

A sprocket chain, arranged and mounted in a manner to be explained later, engages the sprocket wheels 45 so that movement of the carriage 39 above the perforated plate II will at the same time cause the sprocket wheels, and with them the stub shafts t3 and cutter disc 46, to be rotated in a predetermineddirection in order to facilitate the cutting or trimming action performed on the respective edges of the matrix by the beveled knife-like peripheral edges of the cutter discs 46.

In the rear portion of the housing Ill a trans versely-extending bracket '45 (Figs. 2 and 3) is supported at each end onthe rib bars 12. The bracket s9 is cast in the shape shown in Figs. 2 and 3 so as to provide mountings for certain horia'ontal and vertical shafts, to be described, and has an open center portion or well 49" (Fig. 3). As shown in Fig. 3, the bracket is is spaced at a distance back from the rear edge of the perforated plate H and thus is spaced from the rear wall of the vacuum chamber located below the perforated plate 1 i.

Bearing sleeves are mounted in the bracket49 for rotatably supporting the vertical shafts for idler pulleys dd, 5!, 52 and 53 (Fig. 3) around which idler pulleys a sprocket chain 54 passes. This sprocket chain 5e also passes around a sprocket Wheel 55 secured to the upper end of a vertical shaft 56 mounted in suitable bearings Within a sleeve which is supported in the bracket 49. A helical gear 57 is keyed to the lower end of the shaft 55. A chain tightening pulley 58 is mounted at the end of an arm 59 which in turn is pivotally supported at the other end on a stub shaft 6i] secured in the bracket 49. A coil spring (5| engaging the free end of the arm 59, urges the arm 59, and therewith the pulley 58, into chain-tightening position.

The sprocket chain 54. as shown in Fig. 3, passes around a pair of

idler pulleys

62 and 63 at one side of the forward end of the trimmer and around a similar pair of pulleys 6G and 65 at the opposite forward end of the trimmer. The endless chain 5G is secured to bolts or pins 6'6 and 66' on the carriage 39. This arrangement of chain, sprockets and carriage 're'strains the carriage and keeps it perpe'ndicular to the side rails during its travel. s artan of the sprocket chain 54 passes around the two sprocket wheels 45 on the carriage 39, which sprocket wheels 45, as previously described, are keyed to the shafts of the rotary cutter discs 46 (Figs. 4 and 5).

From Fig. 3 it will now be apparent that as the carriage 391s manually moved from the front to the rear of the trimmer, thus in the direction indicated by the arrow on the carriage, the sprocket chain at, with the chain ends secured to the carriage at 66 and 66', will be caused to move, and will in turn cause rotation of the pulleys and sprocket wheels around which the chain 54 passes. The resulting direction of movement of the sprocket chain and resulting rotation of the sprocket wheels and pulleys are indicated by the various other arrows in Fig. 3. In other words, as the carriage 3.9 is moved from the front of the trimmer towards the rear, the rotary cutter discs 46 (Figs. l and will be rotated with the sprocket wheels 45 (Fig. 3) in the direction indicated and thus rotated in the proper direction for trimming the edges of the matrix, at the opposite top edges along the perforated plate H. This 'is an important feature in m matrix trimmer.

t The helical gear 51 (Figs. 2 and 3) rotatedby the sprocket wheel "55,- meshes with a helical gear 51 which is keyed to "a horizontal shaft mounted in suitable hearings in the bracket is. A sprocket pulley 69 (Fig. '3) keyed to the end of the shaft 68, is connected by an endless sprocket chain 10 to a sprocket pulley ll keyed on the corresponding end of a parallel shaft 12. Thus rotation of the shaft 68 produces rotation of the shaft 12, the latter being rotated more rapidly due to the relative sizes of the connected sprocket pulleys 69 and H as indicated in Fig. 3. A second sprocket pulley is is keyed to the opposite or forward end of the shaft 12.

A sleeve (Figs. 3 and 6) extends around the shaft [2, the sleeve it being rotatably supported in bearings, one of which is mounted in bracket at and the other is mounted in a second sleeve ii as shown in Fig. 6. Thus the shaft 12 is retatable within the sleeve 16 and the sleeve 16 is rotatable in the support bearings in the bracket alignment of sprocket H and sprocket 59 when this movement occurs. The reason for this axial 'oriongitudinal movement will be explained presently. A cross arm 18 is secured to the outer end of the sleeve 16. A 'U shaped bracket 19 is mounted firmly at one end of the cross arm '55 and a counterweight 8D is mounted at the opposite end of the cross arm.

A shaft 8| is mounted in suitable bearings 82 in the cross arrn l8 and in the U-shaped bracket 19. A sprocket pulley 83 is keyed to the shaft 8! and is connected by an endless sprocket chain 8% with the sprocket pulley 13. A rotary cutter disc "85 (similar 'to the cutter discs at, Figs. 4 and 5, previously described), is also keyed to the outer end of the shaft 8|. From the description thus far, and with reference to Fig. 3, it will be apparent that rotation of the shaft 12 results in rotation of the cutter disc 85 through the intermediary of the sprocket pulleys T3 and 83 and their connecting sprocket chain 84.

A large gear 15 is keyed and pinned to sleeve 16 and meshes withpinidn gear M (Fig. 3) keyed on the shaft 68. Thus rotation of the shaft 68 also produces rotation of the gear 15 which produces rotation of the sleeve 16 and the cross arm '18. Since shaft 12 is driven from shaft t8 by sprocket and chain and sleeve 16 is driven from shaft 68 by a gear set, they rotate in opposite directions, and also shaft 12 is driven faster than shaft 68, and sleeve '56 is driven slower than shaft 68. Therefore shaft 12 turns several revolutions counterclockwise as viewed in Fig. 3, while cross arm 73 turns one revolution clockwise. The slight axial motion of sleeve 16 described above causes gear 15 and pinion gear is to move slightly out of alignment. However, this motion is but a small portion of the face width of the gears and therefore they do not come out of mesh. Because of this motion it is essential that gears'lli and M be of the straight tooth spur gear type.

A coil spring 92 (Fig. 6) engages gear I5, urges gear l5 and all related parts, namely sleeve it, cross arm it, and cutt'er disc 85, as well as shaft i2 which is constrained to move with sleeve 16 by sprockets ii and 13, to move toward the perforated plate H. This spring 'maintains'a pressure between cutter disc 85 and the semi-cylindrical cutting edge at the inner end 'of the plate -H. cross arm '18 is bent slightly to bring the leading edge of cutter disc 85 into contact with the semi-cylindrical cutting edge of plate I I, thus duplicating the cutting and self-sharpening action of cutters 46 (Fig. 4). The combination of sprockets and gears connecting the cutter discs 45 and cutter disc 85 are such that they produce the same relative motion between cutter disc and cutting edge.

A third sleeve 85 (Figs. 3 and 6) is mounted on the outside of sleeve I1. Sleeve 11 is fastened to bracket 49 by means of screws 93. Pairs of engageable cam elements, one such pair being shown at 88 and 89 in Fig. 6, have their members in each pair so mounted on the outside of the inner sleeve Ti and on the inside of the outer sleeve 86 respectively, and so arranged, that the outer sleeve when rotated approximately one half revolution in the clockwise direction, will rise on the cam surface and contact gear 15. Further rotation of sleeve 86 will move sleeve 86, gear I5, sleeve 15, cross arm I8 and cutter disc 85 away from the semi-cylindrical cutting edge I I, compressing spring 92. This movement is just sufiicient to move cutter disc 85 out of contact with semi-cylindrical cutting edge I I just as cutter disc 85 finishes trimming the edge of the matrix. Sleeve TI is rotatably adjustable by loosening screws 93. Sleeve TI is adjusted so that cutter disc 85 will move away from the semi-cylindrical cutting edge II after finishing its out but before it runs off the matrix support 94.

The sleeve 86 has an annular flange 81 at its inner end. This flange has a short arcuate groove 90 (Fig. 7) adapted to engage a :pin SI (Figs. 3 and 6) carried by large gear I5. After a short rotation of gear 15 and related parts, pin 9i engages flange 81 and sleeve 85 rotates with gear 75, causing the axial motion described above.

As will be apparent from Figs. 1, 2 and 3, the rotary cutter disc 85 is so arranged as to trim the curved inner end of the matrix, while the matrix is held in position on the perforated plate II. The manner in which the cutter disc 85 is automatically operated and controlled is an additional special feature of my invention. When a matrix 98 (Fig. 9) is in position to be trimmed, the edges protrude beyond the cutting edges of plate I! and the inner corner of the matrix, where the trimming of the inner end is to start, is unsupported. This short section of matrix must be supported or the matrix will be torn by the rotating cutter disc 85 as it starts the out. Also cutter disc 85 must be supported in line with the edge of plate I I or the spring 92 (Fig. 6) will move the cutter over until it will strike the corner of plate II when the cutter starts downward. To support the two inner corners of the matrix 98 two

movable supports

94 and 95, one of which is shown in Fig. 9, are located on the two top inner corners of plate I I. These supports are pivoted respectively on

shafts

96 and 95 fastened to the housing I (Figs. 3 and 4). A coil torsion spring 91 (Fig. 9) maintains each support in position while an adjustable stop 95 allows the

support

94 or 94 to be brought into alignment with the semi-cylindrical cutting edge of plate I I.

At the beginning of the trimming operation the matrix to be trimmed is set in desired predetermined position on the perforated plate I I and is secured firmly thereon by vacuum suction.

The cutter disc 85 will be in the position indicated by CI in Fig. '7, and, as shown in Fig. 9, will be in engagement with the corresponding .movable support 94. The pin 9! of the gear I 8 (Fig. 7) by which the flange 81 of the outer sleeve 86 is rotated will be in the full line position at the left end of the slot 95. The carriage 39 (Fig. 3) will be at the front end of the trimmer. With the manual moving of the carriage 39 by the operator from the front end of the trimmer toward the rear, producing movement of the chain 54 and connecting sprocket wheels in the manner previously described, the cutter discs 45 will be rotated and caused to pass along the respective top lateral edges of the perforated plate II, and start to trim the two corresponding lateral edges of the matrix. The cutter disc 85 will simultaneously be rotated (in counterclockwise direction as viewed in Fig. 2) while its support arm-I8 will be moved clockwise, moving the cutter disc 85 down the movable stop until it starts to cut the matrix. As the cutter disc 85 (Fig. 7) progresses it moves off the movable support 94 and onto the edge of plate II as indicated by full line position C2. Continued motion of the carriage 39 advances cutter disc 85 to position 03. Near this point, pin ill of gear 75 engages right end of slot 95 in flange 81. Outer sleeve 86 and gear I5 now rotate together and cam elements 88 and 89 (Fig. 6) are brought toward each other. Cutter disc 35 continues to cut along the semi-cylindrical cutting edge of plate I! and finally leaves the edge of plate II and moves onto the other movable support 94' (Fig. 3) on the left top edge of plate II where cutter disc 85 completes its out through the overhanging edge of the matrix. Outer sleeve 85 has continued to rotate through this cycle of cutting action and at some point after cutter disc 85 has finished its out, but before it runs off a movable support 94, the cam elements 88 and 89 (Fig. 6) come into engagement and compress spring 92 moving cutter disc 85 a suificient distance toward the rear of the machine to cause the cutter disc 85 to clear the movable support 24'. The carriage 39 (Fig. 3) has completed about two-thirds of its total forward motion when cutter disc 85 reaches point Cd in Fig. '7. As the carriage 39 (Fig. 3) continues its forward motion toward completion of trimming the lateral edges of the matrix, cutter disc 85 continues to move toward the top of its swing toward point C5 (Fig. 7) and because'of the engagement of cam elements 88 and 89 (Fig. 6), cutter disc 85 moves further toward the rear. As the carriage 39 (Fig. 3) approaches the end of its travel, the rear edge of the carriage 3S strikes the movable supports St and 94' causing them to rotate on their shafts 96 or 35 (Fig. 9) against their springs 91 in the direction of the arrow Y (Fig. 9), swinging the supports 94 and SM rearwardly and out of the way of the cutters 55 (Figs. l and 5) as these cutters are completing the lateral trimming of the matrix. Since cutter disc 85 has moved into the region of position C5 (Fig. 7) the carriage 39 (Fig. 3) can pass beneath cutter disc 85 without interference. Positive stops (not shown) prevent the carriage 31-) from traveling further toward the rear of the machine than is necessary to complete the lateral trimming of the matrix.

It becomes obvious that the relation between the motion of the cutter disc 85 and the carriage 39 is critical and must be worked out carefully to prevent moving parts from interfering with each other in their motions.

As the carriage 39 is now started on its return to the front of the machine, movable stops 94 and 94' are returned to their original position by their springs 91 (Fig. 9) and relocate themselves against their adjustable stops 95. Outer sleeve 85 (Fig. 7) remains in its, final position until sufficient rotation of gear '55 moves pin 95 to the left end of slot 93 (as viewed in Fig. 7). During this rotation of cutter disc 85 from a position near C to a position near C4, the cutter remains at its maximum rearward position since there is no motion between cam elements 88 and 89 (Fig. 6).

Continued return motion of carriage 39 (Fig. 3) now causes additional rotation of arm and cutter disc 85. Since in moving from a position near Cd (Fig. 7) towards C3, sleeve 86 rotates with gear E5, the cutter starts to move toward the front of the machine due to the relative motion between cam elements 8d and 89 (Fig. 6). Near the position C3 (Fig. '7) there has been sufficient forward motion of cutter disc 85 to allow it to again contact the semi-cylindrical cutting edge of plate. H. The cam elements 88 and 83 (Fig. 6) move further away from each other during further motion, allowing spring 92 to maintain a pressure between cutter disc 35 and semi-cylindrical cutting edge of plate H.

When the carriage 39 (Fig. 3) is fully returned to its initial position, cutter disc 55 again assumes position CI (Fig. '7) and pin BI is i the full line position shown at the left in slot 96. Thus with my improved matrix trimmer,

constructed substantially as illustrated and described, the three edges of the matrix are trimmed simultaneously during the short interval required for moving the carriage rearwardly on the trimmer.

At the conclusion of the trimming, the vacuum suction is shut off, the trimmed matrix is removed from the perforated plate II. The trimming of the matrix is accomplished While the matrix, is held exactly in the same curved position as it will be held in the subsequent casting of the stereotype plate thus insuring a higher degree of accuracy in the size of the trimmed matrix, and, if desired, the matrix can bekept heated by the heating elements 24 (Fig. 2) during th positioning and trimming of the matrix.

The setting of thematrix in desired predetermined position on the perforated plate II is done with the aid of the projectors 25 (Fig. 1) previously mentioned. When a predetermined marginal spacing is to be maintained at one edge, for I example, at the top of the final printed page with a series of matrices, I have found that considerable time can be saved in the setting of the projectors by the employment of an adjustable guide bar on the top edge of the perforated plate H. Such a guide bar iS shown by itself in Fig. 8, and its position on the trimmer for the setting of the projectors is indicated by the broken lines (Fig. 2).

Referring to Fig. 8, the uide bar consists of a. main bar-like member 28 adapted to rest on a rib bar !2 (Fig. 2)., and having downwardlyextending flanges 29 and Si! at each end adapted to extend over the outer faces of the end walls of the vacuum chamber for the perforated plate H. Preferably a spring-pressed engagement of element 3! is mounted inthe end of the mem ber 23. to insure the guide being held securely in place during the setting operation.

A pair of, curved locating, plates 3d are secured to the inner edge of the member 28. near eating plates 34 are each secured to the member 28 by a pair of screws 35 which pass through an elongated slot 34' in the top of each locating plate so as to permit some lateral adjustment of the locating plate to take place. Each locating plate 3d has a cut-out portion over which an adjustable indicator 3% is placed and which is secured to the locating plate 36 by top and bottom screws 31 extending through slots 38 so as to permit some up and down adjustment of the indicator 36 on the plate 34. Each indicator 36 carries a circular marker 36 having the customary horizontal and vertical cross diameter lines so that the center points of the marker can easily be seen, the circular marker 36 being formed of opaque materiaI and set in an aperture in the indicator 36. Any suitable material may be used in alternate q adrants to give contrast, thus enabling the center point of the marker to show up even more clearly. When the guide bar is set in place and properly ad usted, with the circular markers 36' set at the desired distance below the top edge of the plate for the corresponding marginal spacing to be maintained above predetermined points on the matrices, the two opposite projector assemblies are then adjusted so that the cross hairs will be focused exactly on the center points of the circular markers 35', whereupon the projectors are locked in such position and the guide bar is then removed.

A number of minor modifications in the trimmer as described would be possible within the scope of my invention. It is not my intention to limit my invention except to the extent set forth in the claims.

I claim:

1. In a matrix trimmer, a matrix-holding plate having parallel side edges and an inner edge, said plate mounted in said trimmer, means for holding a matrix securely in set D0- sition on said plate, a carriage movable over said plate in a direction parallel to said side edges, a cutting element at each end of said carriage adapted to out along said side edges of said plate respectively as said carriage is moved over said plate in said trimmer, and additional cutting means located beyond the inner edge of said plate in said trimmer, adapted to out along said inner edge of said plate and actuated by the movement of said carriage, whereby the trimming of the matrix along both side edges and along the inner edge of said plate can take place simultaneously while the matrix is held in position on said plate.

2. In a matrix trimmer, a matrix-holding plate having parallel side edges and an inner edge, said plate mounted in said trimmer, guidins means for setting a matrix in exact trimming position on said plate, means for holdin a matrix securely in position on said plate, a carriage movable over said plate in a direction parallel to said side edges, a rotary cutter disc at each end of said carriage adapted to out along said side edges of said plate respectively as said carriage is moved over said plate, means for rotating said cutter discs, an arm located beyond the inner edge of said plate'in said trimmer, said arm mounted to swing in an arc in a plane perpendicular to the side edges of said plate, a cutting element on said arm adapted to out along said inner edge of said plate, and means for swinging said arm.

3. In a. matrix trimmer, a curved, matrixholding plate having straight, parallel side edges,

focusing light assemblies mounted above said side edges and directing focused light to predetermined points at opposite sides on said plate for guiding the setting of a matrix in desired exact position on said plate, means for holding the matrix securely on said plate after the matrix has been properly positioned with the aid of said light assemblies, a carriage movable above said plate and the positioned matrix in a direction parallel to said side edges, a rotary cutter disc at each end of said carriage adapted to cut along said straight side edges of said plate respectively as said carriage is moved over said plate and matrix in said trimmer, and means, actuated by th movement of said carriage, for rotating said cutter discs. I

4. In a matrix trimmer of the character described, a curved, perforated, matrix-holding plate having straight parallel side edges, a vac-'- uum chamber connected with said perforated plate for holding a matrix securely in set position on said plate, a carriage movable above said plate in a direction parallel to said side edges, a rotary cutter disc at eachend of said carriage adapted to out along said straight side edges of said plate respectively as said carriage is moved over said plate in said trimmer, and a chain and pulley assembly, operated by the movement of said carriage, for rotating said cutter discs.

5. In a matrix trimmer of the character described, a curved, matrix-holding plate having straight parallel side edges and a curved inner edge, means for holding armatrix securely in set position on said plate, a carriage movable above said plate in a direction parallel to said side edges, a cutting element at each end of said carriage adapted to cut along said straight side edges of said plate respectively as said carriage is moved over said plate in said trimmer, additional cuttin means located beyond the inner curved edge of said plate in said trimmer adapted to out along said inner curved edge of said plate, and means, actuated by the movement of said carriage, for operating said additional cutting means, whereby the trimming of the matrix along both side edges and along the inner edge of said plate can take place simultaneously with the movement of said carriage while the matrix is held in position on said plate.

6. In a matrix trimmer of the character described, a curved, matrix-holding plate having straight parallel side edges and a curvedinner edge, means for holding a matrix securely in set position on said plate, a carriage movable above said plate in a direction parallel to said side edges, a rotary cutter disc at each end of said carriage adapted to out along said straight side edges of said plate respectively as said carriage is moved over said plate, an arm located beyond the inner curved edge of said plate in said trimmer, said arm mounted to swing in an arc in a plane parallel to said inner end of said plate, a cutting element on said arm adapted to out along said inner curved edge of said plate, and means, actuated by the movement of said carriage, for rotating said cutter discs, and connected means for swinging said arm.

7. In a matrix trimmer of the character described, a curved, perforated, matrix-holding plate having straight parallel side edges and a curved inner edge, a vacuum chamber below said perforated plate for holding a matrix securely in set position on said plate, a carriage movable above said plate in a direction-parallel to said side edges, a rotary cutter disc at each end of said carriage adapted to out along said straight side edges of said plate respectively as said carriage is moved over said plate, spring elements holding said cutter discs in cutting engagement with said side edges of said plate respectively, an arm located beyond the inner curved edge of said plate in said trimmer, said arm mounted to swing in an arc in a plane parallel to said inner end of said plate, a rotary cutter disc on said arm similar to said'cutter discs on said carriage and adapted to out along said inner curved edge of said plate, and a chain and pulley assembly, operated by the movement of said carriage, for rotating said cutter discs and for swinging said arm, whereby the trimming of the matrix along both side edges and along the inner edge of said plate can be caused to take place simultaneously with th movement of said carriage, 7

8. A matrix trimmer of the character described including a curved, matrix-holding plate having straight parallel side edges and a curved inner edge, said plate mounted in said trimmer, guiding means for setting a matrix in exact trimming position on said plate, means for holding a matrix securely in predetermined position on said plate, a carriage movable over said plate in a direction parallel to said side edges, a cutting element at each end of said carriage adapted to out along said straight side edges of said plate respectively as said carriage is moved over said plate in said trimmer, an arm located beyond the inner curved edge of said plate in said trimmer, said arm mounted to swing in an arc in a plane parallel to said inner curved edge of said plate, a cutting element on said arm adapted to out along said inner edge of said plate, means for swinging said arm in synchronism with the movement of said carriage, and means in said arm swinging means for holding said cutting element on said arm in cutting engagement with said inner curved edge of said plate during the trimming of the matrix.

9. A matrix trimmer of the character described including a curved, perforated, matrix-holding plate having parallel side edges and a curved inner edge, said plate mounted in said trimmer, light projectors for setting a matrix in exact trimming position on said plate, a vacuum chamber connected with said perforated plate for holding a matrix securely in predetermined position on said plate, a carriage movable over said plate in a direction parallel to said side edges, a rotary cutter disc at each end of said carriage adapted to out along said straight side edges of said plate respectively as said carriage is moved over said plate in said trimmer, an arm located beyond the inner curved edge of said plate in said trimmer, said arm mounted to swing in an arc in a plane parallel to said inner curved edge of said plate, a rotary cutter disc on said arm similar to said cutter discs on said carriage and adapted to out along said inner curved edge of said plate, means, actuated by the movement of said carriage, for rotating said cutter discs, and connected means for swinging said arm.

10. A matrix trimmer of the character described comprisinga curved, perforated, matrixholding plate having parallel side edges and a curved inner edge, said plate mounted in said trimmer, light projectors for setting a matrix in exact trimming position on said plate, a vacuum chamber below said perforated plate for holding a matrix securely in predetermined position on said plate, a carriag'e movable above said plate in a direction parallel to said side edges, a rotary cutter disc at each end of said carriage adapted to cut along said straight side edges of said plate respectively as said carriage is moved over said plate in said trimmer, an arm located beyond the inner curved edge of said plate in said trimmer, said arm mounted to swing in an arc in a plane parallel to said inner curved edge of said plate, a rotary cutter disc on said arm similar to said cutter discs on said carriage and adapted to cut along said inner curved edge of said plate, a chain and pulley assembly, operated by the movement of said carriage, for rotating said cutter discs and for swinging said arm, and meansfor holding said rotary cutter disc on said arm in cutting engagement with said inner curved edge of said plate during the trimming of the matrix.

11. The combination set forth in claim 5 with the addition of a pair of movable supports mounted in said trimmer at the two inner corners of said curved matrix-holding plate for supporting the corresponding corner portions of the matrix on said plate. 1

12. The combination set forth in claim 5 with the addition of a pair of movable supports mounted in said trimmer at the two inner corners of said curved matrix-holding plate for supporting the corresponding corner portions of the matrix on said plate, and spring elements normally holding said supports in desired position but permitting said supports to be temporarily pushed out of position when contacted by said carriage so as to move said supports out of the way of said cutting elements on said carriage.

13. The combination set forth in claim 6 with the addition of a pair of movable supports 3 mounted in said trimmer at the two inner corners of said curved matrix-holding plate for supporting the corresponding corner portions of the matrix on said plate, means for adjusting the position of said movable supports, and spring elements normally holding said supports in desired position but permitting said supports to be temporarily pushed out of position when contacted by said carriage so as to move said supports out of the way of said rotary cutter discs on said carriage.

14. In a matrix trimmer of the character described including a curved, matrix-holding plate having straight parallel side edges, means for holding a matrix securely in position on said plate, and means for simultaneously trimming the edges of said matrix along said edges of said plate, light projectors adjustably mounted on said trimmer above the side edges of said plate for directing the setting of the matrix in exact desired trimming position on said plate, and a guide bar adapted to be temporarily placed on one of said edges of said plate for facilitating the ad justing of the light projectors above the opposite side of said plate in preparation for the setting of the matrix in position.

CRAIG -C. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 802,572 King Oct. 24, 1905 846,259 Swan et a1. Mar. 5, 1907 2,538,972 Magnoni Jan. 23, 1951 FOREIGN PATENTS Number Country Date 10,153 Great Britain Apr. 24, 1914 445,663 France Sept. 10, 1912