US2928161A - Plate supporting and clamping apparatus - Google Patents

Description

March 15, 1960 G. N. KRUEGER 2,928,161

PLATE SUPPORTING AND CLAMPING APPARATUS 5 Sheets-Sheet J.

FiledFeb. 19, 1957 INvENToR GLENN N. KRUEGEE fig March 15, 1960 G. N. KRUEGER PLATE SUPPORTING AND CLAMPING APPARATUS Filed Feb. 19, 1957 3 Sheets-Sheet 2 N INVENTOR GLENN N. KRUEGER If wwflglw, flaw/M ATTY.

G. N. KRUEGER PLATE SUPPORTING AND CLAMPING APPARATUS 3 Sheets-Sheet 3 W a M o m m WM x. mm m n plcu V 5 J March 15, 1960 Filed Feb. 19. 1957 ATTYS,

United stms atfi 073C? PLATE SUPPORTING AND CLAMPING APPARATUS Glenn Krueger, North Riverside, Illi, assignor Miehle-Goss-Dexter, Incorporated, Wilmington; Del., a corporation of'Delaware Application February 19 1 957,S erial No, 641,036

10 claims. or. 29 -2H the plates and apply circumferential tension to draw themlsecui'ely against the press cylinders. For receiving the hooks or fingers of the plate holdingmechaiiisms, recesses, called tensionlockup pockets; aremilled inthe underside of the curved printing plates adjacent their straight edges. It'is customary to'rnillsuch recessesf or pockets after the printing plates have otherwise" been completely prepared for printing, including the ste'p of shaving the undersides of such. plates" to-a finisheddie m'ension conforming to' the" outer" surface of 5 a printing cylinder in order to-obtain' accuracy in 'locatin'g"the terisi on lockup pockets. I Stereotype printing plates which are to print ordinary copy in black ink are positioned on the'different'press cylinders for sidelay and circumferential register. Accordingly, in finishing: such plates, the tension lock-up pockets milled in the unclersides of each plate-should'jbe located in substantially 'thesameposition with respectdo the copy on the outside of the plates; Stereotype printing plates which are to printan image in' colo'r, however; must be registered exactly onthe different p'resscylin'd'ers so that each color image printed is' in perfect re'gister with previously printed images; The" tensionlockup pockets in each of the several plates required to printer color image should'be located' in the same position with respect to the image on the plate, in order to permit final adjustment for exact register by means of 'th' plat e adjusting mechanism provided 'in conjunction with -the plate lockup mechanism onthe press'cylind'rf Milling machines particularly adapted to prepare stereotype printing plates by cuttingp'o'ckets on the underside of the plate have'becoinewell known? An exainple of an improved plate finishing machine of this type may be seen by reference toapplicants relafe'd'app'lication, Serial No. 641,176, filed February 19; 1957;

clamping apparatus so that 'the'"*plate"-can be accurately v loeatedibefore being cu-t.

. 2,928,161 fiiQ-Md'? 15%. 1.

Accordingly,it is a general object of the invention to provide clamping apparatus for a plate finishing chine for holding a stereotype printing plate in 126s formilling which is effective to prevent moyem'e" the plate during operation of the milling unit yet does not damage ordistort the plate or its printingiimiage'; more detail, it is an object is provide clamping app ms for a saddle type plate finishing machine for? a p in'g clamping pressure to a plate on the saddle at steady rate and uniformly byrnea'ns of a curved res" ant band so that the plate is not-m'a r'red'nor is it" SjtraihEii out ofaccurate alinernent. p v It is, another object to proyide a, plate cramping am} su porting apparatus that permits accurate r' 'e'gis any portion of a plate surface. A* furthei obj provide a' clamping apparatus which isconve'm"" mounted over the saddle of the machine 'for' lengthwise sliding movement-relative to the same, so that thclanip ing apparatus may be easily shifted away from the regi'dii of the saddle in which the plateis to be machine" 6 permit the plate to be accurately located prior to" ehining'. A related object' is tomoun't' the clamping paratus on a yielding support so as to take upany dc"- flection during clamping.

In'more detail, an object isto provideaclampha a rigid arcuate body moiinted to' lie adjacent to butspaced above the saddle slightly riiore'tha'n the" thickness are printing plate, and a resilient band supportedby body and movable by' an actuator controlled by pressure fluid to expand'into contactwith' a plate'to" fimrly- Hold thes'ame on the saddle. Another object is to provide ail, important safety feature by employing means limiting the" movement of the" clamping-band," thuspi'ov'idi a safeguard against' the" actuator for the clampburst' as. whentheclampis ac'tuated'whe're no pla'te 'is under the" clamp, or" due to the application'of excessive "fluid press;

substantially in the plane of lines -.'l-:-.-7'of Fig. 5.

sures. his a further object to provide aclampin'g apparatus of this type' that is convenient and simple" tdo 'erate, "in: expensive" to manufacture; andconstructed' forlong fe under rigorous use. It is arelated' object to' rovide suich an'apparatus that is self adjustin'g and eas'yto maint in: Other objects and advantages of theinvention will be com'e" apparent from the attached" description and upon referenceto the drawings,iin which: n V 7 Figure 1 is a perspective 'view oi? a' plate finishing;Ina chine equipped with plate clamp apparatus" constructed in'accord-with' this invention; Figs. 2 and 3 areat'op' plan view"and' a"side elevation view; respectively, of the machine ofFigure 1;

Fi'g.-4- isa'sectional view taken' substantiall'y" iii th plane of lines 4- 4 of'Fig: 2; r Fig.5 is an enlarged sectional view ofone plateclamp' taken substantially in the-plane 'of"lines'-'5 5'of"Fi 4" Fig. '6 is an enlarged fragmentary sectional vie one plate clamp taken substantially" in the plane oflines. 6,6'"of Fig. 5 and showingapart of the lowefend oftheclamn; and l L Fig. 7 is a 'section'aFview .of oii'e' plate clamp taken While the invention is susceptible of {various mbd'ific tions and alternative constructions, a preferred embodfi ment-has' been shown inthe" drawings" and 'will be desc'ribed in'detail. It should be understdod, however; that there is" no. intention to'lirnit the"invention route specific form disclosed, but on the contrary, the in tionsyand equivalentifallin g' within thespir'it and of: the invention as expressed in the appended claims? G enral machine or gdhi 'z'aiiori Upondmore s ecific:rerernee w tu "hammerswill be understood that the clamping apparatus of this invention is shown as embodied in an illustrative stereotype printing plate finishing machine which may be made as part of a complete production type unit for making stereotype plates. This machine is used for milling tension lockup pockets in the inner surfaces of the plates. A detailed description of such a production unit including a detailed description of the operating components of the particular finishing machine 20 shown in Figure 1, is contained in the aforementioned co-pending application, Serial No. 641,176, filed February 19, 1957. Insofar as is helpful to obtain a complete understanding of the present invention and by way of setting the general environment for this invention, the machine 20 of Figure 1 will be described in brief.

It is customary to make this milling machine 20 as an entirely separate unit, and in independent operation as it might be shown in this figure, the machine may be supplied with plates requiring tension lockup pockets from any plate production method. Accordingly, turning to Figs. 1-4, the machine comprises a waist-high frame having a massive curved saddle 26 ribbed underneath for strengthening purposes, and which is provided for supporting a semi-cylindrical stereotype plate, duringthe operation of milling pockets in the underside of the plate. The curved saddle 26 is elongated and extends lengthwise of the machine, and the printing plate to be milled'may be slid from the right-hand end 24 of the machine 20, as viewed in Figure 1, along the saddle to a central region where elongated openings 27, 28 are provided through which a pair of cutters 30, 31

of a milling unit 32 reach to engage the inner surfaces of the plates to mill the pockets. Inthis central region of the saddle 26, clamping apparatus 35 constructed in accord with the present invention may be utilized for clamping the plate on the saddle during a pocket milling operation, and it is with this clamping apparatus that 'we are principally concerned. This clamping apparatus provides, in the present instance, a pair of rigid ' arcuate clamp bodies 36, 37 each having a band 38 which engages the outside of a plate positioned on the saddle of the machine beneath the clamps to hold it firmly on the saddle. In the exemplary form of the invention shown, air under pressure is supplied to an actuator associated with each of the clamp bodies to move the bands and operate the clamps.

Continuing the general description of the machine 20, the frame of the machine beneath the saddle 26 is provided with horizontally extending ways 39 providing inwardly sloping way surfaces 40 forming a track for the milling unit 32. This milling unit 32, in the present instance, embodies a sliding'carriage 42 carrying a pair of milling heads 43, 44 under the saddle. These milling heads are adapted to be rocked in unison, into and out of engagement with the inner surface of a printing plate clamped on the saddle. For this purpose the machine provides cam or tracer control for the milling heads which is effective as an incident'to travel of the carriage along the ways for causing the cutters to move successrvely into and out of engagement with the inner surface of the plate as the milling unit moves along under the plate. Thus the milling unit 32 is employed to cut a pattern of spaced tension lockup pockets or recesses along both straight edges of the plate clamped on the saddle.

The carriage 42 is moved along the ways by means such; as an electric motor (not shown) carried by the carnage and controlled by push buttons or other controls located together in a control box 45 at the right-hand end of the machine as viewed in Figure 1. Means are also provided for adjusting the saddle 26 of the machine to vary the position of a plate resting on the saddle with relation to the milling unit supported by the carriage and under the saddle. Controls for making these saddle adjustments may be in the form of hand whee s 46., 7

4 controlling linkages and gearing at opposite ends of the machine for appropriately moving the machine saddle.

For the purpose of providing power for operating the milling unit, various arrangements may be provided, although in the machine of the aforementioned co-pending application the same motor (not shown) mounted on the carriage for driving the milling unit axially beneath the saddle also supplies power to the milling heads to rotate the cutters. Thus in this machine 20 the milling unit 32 comprises a unitary assembly of substantial weight resting on the machine frame ways, and provides a stable platform for the milling cutters enabling their operation with greater precision and at higher cutting speeds. Suitable means (not shown) may be provided for supplying electric power to the motor on the traveling carriage, controlled by means of the control box found on the right-hand side of the machine as viewed in Figure 1.

As indicated most clearly in Figures 13, the machine 20 may be provided with means for locating stereotype plates on the saddle of the machine, in the present instance comprising stops controlled by handles 56 found at one end of the saddle. These plate steps 55 are arranged on both sides of the saddle towards the righthand end of the machine as viewed in Figs. 1-3, the end of the machine on which the plates are first received, and serve as locating stops against which the plate abuts prior to clamping so as to properly position the plate for receiving the tension lockup pockets. So as to enable a printing plate to slide past these stops 55 without manual manipulation, the stops 55 are spring biased to the erect position in which they are shown in these figures. Thus the stops are depressed by the weight of a plate as it slides over them to the central machining region of the saddle. Stops 57 may also be provided towards the terminal end of the saddle 26, for skewing a plate on the saddle before clamping for color plate registering purposes. Such skewing stops 57 are normally drawn away from the plate engaging position when ordinary black printing plates are machined by means of operating handles 57. It will be understood other mechanism may be employed for locating the plate or adjusting it with relation to the saddle 26 than that shown herein, this form being depicted for illustrative purposes only. In addition to providing for milling pockets in the inner surface of the plate, this machine 20 also ordinarily provides means (not shown) for trimming opposite corners of the plate for sidelay registry purposes. The supports 58, 59 for the trimming cutter shafts 60, 61 are mounted on the frame of the machine, as shown in Figure 1.

Plate clamping apparatus For holding a plate on the saddle of the machine 28 during the milling operation, the present invention provides pressure fluid operated clamping apparatus 3 5, shown in Figure 1 positioned over a plate P located in the central region of the saddle 26. As described hereinbefore, with the plate P held rigidly on the saddle 26, the milling unit 32 under the saddle is effective to mill tension lockup pockets adjacent both straight edges of the plate.

The cutters of the milling unit reach through the elongated openings 27, 28 (Fig. 4) in the saddle 26 to engage the inner surfaces of the plate P mounted on the saddle for milling purposes. The contour of the saddle 26 is cylindrical to conform to the finished inner surface of a stereotype printing plate, and the saddle provides a reference surface on which the plate may be accurately located so as to enable the tension lockup pockets to be precisely located in the plate. For facilitating such adjustment, provision may be made such as plate locating stops 55 and skewing stops 57, as described earlier, carried on the saddle and adjusted by means of control handles 56, 57 respectively.

,In carrying out the invention, the clamping apparatus ,74, 75 of the clamping rings.

.also the return'springs'of the assembly.

by cooperating with the flanges 7,4, 75 of theclamping embodies a pair of arcuate' clamps embodying;- clamp bodies 36, 3 1 aremounted over the saddle such as to: permit adjustment lengthwise thereof in order to Be positioncd over a plate Iocated on the saddle as shown in Figure I. Ordinarily in clamping a plate these clamp bodieswould be spaced apart somewhat less than the width of the; plate. For supporting the clamp bodies 36, 37 on the frame 25 of the machine, parallel rods 65, which lie lengthwise of and adjacent to the saddle are utilized; The ends of the clamp bodies 36, 37 are sl'idably supported on rods 65, 66 by means of bushings 69, 70 which also act as spacers to hold the clamp bodies apart; The arcuate clamp bodies, as shown in Figures 1 and 4, are curved to closely overlie the saddle "and in the present instance are spaced slightly more, perhaps" Ma", than the thickness of aprinting plate from the surface of the saddle, as shown in Fig. 61

In accordance with the present invention, for clamping purposes a resilient band 38 is mounted under each clamp body 36, 37 and an actuator is associated therewith, operated by pressure fluid, for moving the band 38 into engagement with a plate P under the clamping apparatus. for urging the plate onto the saddle with uniform pressure and thus for holding it in position without distortion. Since the clamps of the apparatus are alike,

the description which follows applies to both clamps.

For supportinng the resilient band'38, the arcuate rigid clamp back or body 36 is channeled and receives curved mountingrings 72, 73 L-shaped in section on the under side along the opposite edges. The flanges 74, 75 of the L-shapedv mounting rings 72, 73 are so dimensioned as to. leave a slot 76' running lengthwise of the clamp body on the under concave side 77, the width of the slot: being substantially less than the over-all width of the clamp body, as shown in Fig. 5. The resilient band 38" fits in the slot 76v with some play to permit in. and

out movement.

In the present instance the actuator 71 comprises a flexible diaphragm 80, made of cordedrubber fabric, for example, which is held in position over the channeled 6 If no: plate is under the clamp, the band 38 moves outwardly' until the plate 82 is stopped by the flanges 74, 75 of the mounting rings and the waved springs 86, 87 compressed between these members.

In the present instance the backing plate 82 for the resilient band 38 terminates a short distance from the end of the pressure fluid chamber formed within the concave under surface 81 of the clamp body 36 by means .extend'slaterally on both sides of the band, as shown in Big. 5., and, presents portions lying behind thev flanges A thin strip of steel. 84 approximately .010" in thickness is placed between strip Bland the diaphragm to protect the diaphragm from possible damage from burrs or scufling of rivets during operation. This strip is the same width and length. as strip82.

For. supporting the band 38 in place a strip Between the lateral flanges 74, 75 of the clamping I supported on the clamping band 38, strips of spring steel 86, 87' waved. or serpentine in form are inserted. These strips 86,-.87 functionas springs for returning the band 38 to:withi n the clamp body 36 upon release of fluid pressure. The backing. plate 82 for. the band 38, in the present instance, performs a multiple function. It presents arigid member which holds the band in position. The plate-82 also coacts with the diaphragm and In addition,

rings, it operates to limit the outward movement of the-band; Upon the application of pressure fluid to the chamber,, diaphragm 80" stretches, and moves-the band "38'outwardly through the slot 76't0 extend from the clamp body 36 for engagement with the plate P located under the clamping apparatus 35 on the saddle of the machine.

clamp body, which is defined at each end of the body by diaphragm end clamps 88. One of these end clamps 88 appears in section in Fig; 6. Over extended periods of operation of the clamp actuator 71, it has been found that the diaphragm has been damaged inthe regions adjacent the ends of the steel strip 84 due to rubbing or abrasion between the strip and the diaphragm; To prevent such damage in the present instance, shortend strips 89 are placed between the diaphragm and the ends of the backing-plate at each: end of: the clamp; Only one of these end strips 89appe'ars in the drawings, also in Fig. 6. It will be apparent from the drawing that the end strips extend under end clamps; 88 and are held in place by them.

A further feature contributing to the trouble-free operation of' the clamping: apparatus illustrated, is provided by the mounting arrangement for the spaced clampsl- In the present instance, mounting rods 65, 66 are employed located on each side of the saddle and so positioned as to enable manual sliding movement of the clamps to a position over the central region of the saddle and over pressure fluid actuator 72 for eachclamp maybe operated toexpand the resilient band 38 into engagement with the outside of the printing plate P. In the present instance, the (Fig. 7) clamping band 38 is made of a somewhat resilient yet tough substance such as hard gum rubber which will not abrade or mar the outside of the stereotype plate. Since the outside of the plate already carries the printingirnage it is essentialthat the same not be damaged by the clamping. apparatus.

To resist transverse binding while still allowing flexure lengthwise to conform to the concavity of the' clamp body the backing stop or plate 82 must be made of a relatively stiff and strong material such as spring steel. With such 'a material forming the backing for the band, and with the pressure fluid actuator shown as exemplary in the drawings, the clamping bandupon: actuation engages a plate in such a manner as to minimize the chances of marring the outside surface of the plate and distortingthe plate. In part this is clue to the feature that the clamping band apparently does not engage the outside of the plate throughout its length at the same instant. Rather, from observation, it has been concluded that initially the plate is engagedby the band intermediate'the ends thereof, that is to say, over the crown of the saddle, and clamping e'ngagement proceeds in both directions towards the respective ends of the clamp. It is evident'that'the time interval during which this occurs is of very short duration. The clamping band in all regions thus presses squarely against the outside of'the'plateand there is an absence of rubbing even during initial pressure application.

Moreover, there is an entire absence of. circumferential stresses applied to the plate and, as a result, thereisino tendency to shift the" plate on the" saddle duringclamp actuation. p

Iclaim asmyinvention:

V 1". In a machine forfinish'in'g curved'stereotype printing plates and having a frame supporting a cutter which engages the inner surface of the plates, a plate-supporting and clamping apparatus comprising, in combination, a saddle on said frame having an opening permitting-said cutter to operate therethrough, said saddle being curved to support a plate,:an arcuate clamp positionable over said saddle, means for supporting said clamp on said frame including parallel rods lying lengthwise of and adjacent to said saddle, said rods being supported by the machine frame, said clamp having a clamp body supported at its ends by said rods and being curved to closely overlie said saddle, and pressure fluid means carried by said clamp body, said pressure fluid means including a clamping band supported on the underside of said body and operable when the clamp is positioned over a plate on said saddle to move into engagement with the plate for urging the plate onto the saddle with uniform pressure and holding it in position without distortion.

' 2. In a machine for milling tension lockup pockets in curved stereotype printing plates and having a frame supportinga cutter which engages the inner surface of the plates, a'plate-supporting and clamping apparatus comprising, in combination, a saddle on said frame having an opening permitting said cutter to operate therethrough,

said saddle being curved to support a plate, an arcuate clamp positionable over said saddle, said clamp having a clamp body curved to closely overlie said saddle, means for supporting said clamp body on said frame, said support means allowing for adjusting the position of said clamp body lengthwise of the frame, and means carried by said clamp operable when the clamp body is positioned over a plate on said saddle for engaging the said plate, said last-named means including a resilient band supported on the underside or said clamp body for urging the plate .onto the saddle with uniform pressure and thus holding it in position without distortion.

3. A pressure fluid operated clamp comprising, in combination, an arcuate clamp body, means on the concave underside of said body forming a lengthwise slot, a resilient band in said slot and movable outwardly to extend from said clamp body for clamping purposes, said clamp body forming a chamber for pressure fluid behind said band, a pressure responsive member mounted in said chamber for moving said band, and an inflexible plate attached to .said band to extend laterally thereof, said plate being sub- ,stantially wider than said slot to limit the outward movement of said band upon the application of pressure fluid to said chamber.

4. A pressure fluid operated clamp comprising, in combination, an arcuate clamp body having means forming a slot running lengthwise of the body on the under concave side thereof, a resilient band in said slot and movable outwardly to extend from said clamp body for clamping ,purposes, said clamp body forming a chamber for pressure fluid behind said band, a pressure responsive'mem- 'ber mounted in said chamber for moving said band, an

inflexible plate attached to said band to extend laterally thereof, said plate being substantially wider than said slot to limit the outward movement of said band upon the application of pressure fluid to said chamber, and an elongated waved spring acting against the lateral portion of said plate for returning said band upon the release of pressure.

5. A pressure fluid operated clamp comprising, in commeans carried by said band and cooperating with a stop on the clamp body for preventing said diaphragm from bulging out said wall opening under excessive pressure conditions.

6. A pressure fluid operated clamp comprising, in combination, a clamp body including a side wall having an opening therein, a chamber for pressure fluid formedin said body behind said wall, a diaphragm completing said chamber, a resilient clamping member supported in the wall opening and movable by said diaphragm to extend from said body for clamping purposes, andstop means carried by said clamping member for preventing said diaphragm from bulging out said wall opening under excessive pressure conditions.

7. A pressure fluid operated clamp comprising, in combination, an arcuate clamp body having a chamber extending lengthwise thereof for pressure fluid leaving a slot to the concave side of said body opening to the outside of said body, a diaphragm positioned acrosssaid slot, a resilient band supported within the clamp body in the slot and movable by said diaphragm upon the application of pressure to extend from said body for clamping purposes, and spring means carried by said bodyfor returning the band within the clamp body upon release of pressure. v

8. A pressure fluid clamp comprising, in combination, a clamp body forming a chamber for pressure fluid, a diaphragm closing said chamber, a resilient band supported by said body and movable by said diaphragm for clamping purposes, and means carried by said resilient band cooperating with means carried by said body for limiting the movement of said band thus safeguarding the diaphragm from bursting under excessive pressure conditions. r

9. In a machine for finishing curved stereotype printing plates and having a frame supporting a cutter which engages the inner surface of a plate to be finished, plate supporting and clamping apparatus comprising, in combination, a curved saddle carried by said frame having an opening for said cutter to operate through, anarcuate clamp carried by said frame over said saddle, said clamp having a rigid clamp body curved to closely overlie said saddle and spaced uniformly therefrom at a distance slightly more than the thickness of a plate so as to permit a plate to be positioned on said saddle under said clamp body, and pressure fluid means supported by said clamp body including a flexible clamping band mounted on the underside of said body and engageable with a plate on the saddle, said last-named means being operable to move said clamping band into engagement with a plate for urging the latter onto the saddle with uniform pressure and thus holding it in position without distortion.

10. In a machine for finishing curved stereotype printplates and having a frame supporting a cutter which engages the inner surface of a plate to be finished, plate supporting and clamping apparatus comprising, in combination, a curved saddle carried by said frame having an opening for said cutter to operate through, an arcuate clamp carried by said frame over said saddle, said clamp having a rigid clamp body supported at its ends on said frame and curved to closely overlie said saddle and spaced uniformly therefrom at a distance slightly more than the thickness of a plate so as to permit a plate to be positioned on said saddle under said clamp body, and pressure fluid means supported by said clamp body including a flexible clamping band mounted on the underside of said body and engageable with a plate on the saddle, said last-named means being operable to move said clamping band into engagement with a plate for urging the latter onto the saddle with uniform pressure and thus holding it in position without distortion.

References Cited in the file of this patent UNITED STATES PATENTS 2,366,666 Chapman Jan. 2, 1945 2,537,604 Ricards et al. Jan. 9,1951 2,640,565 Hoppenstand Jan. 2, 1953 2,673,573 Fawick Mar. '30, 1954 2,680,405

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