US2884854A - Rotary hectographic duplicating machines - Google Patents

Description

y 1959 E. BROUGHAM ET AL ROTARY HECTOGRAPHIC DUPLICATING MACHINES 4 Sheets-Sheet 1 Filed June 19. 1956 Kin!) bi Etlw:

m n w w m y 1959 L. E. BROUGHAM ET AL 2,384,854

ROTARY HECTOGRAPHIC DUPLICATING MACHINES Filed June 19. 1956 4 Sheets-Sheet 2 y 1959 E. BROUGHAM ETAL 2,884,854

ROTARY HECTOGRAPHIC DUPLICATING MACHINES Filed June 19. 1956 4 Sheets-Sheet 3 I e 5 :i-

AWE/V7016 May 5, 1959 I L. E. BROUGHAM ETAL ROTARY HECTOGRAPHIC DUPLICATING MACHINES Filed June 19. 19.56

4 Sheets-Sheet 4 fen Ear Bea (/GHAM LESLIE y 2 M v z 5% W fi/ 3W Zv ROTARY HECTOGRAPHIC DUPLICATING MACHINES Leslie Ernest Brougham and Roland Brown, London,

England, assignors to Block & Anderson Limited, London, England, a British company Application June19, 1956, Serial No. 592,435

Claims priority, application Great Britain June 28, 1955 Claims. (CL 101-1325) The present invention relates to rotary printing or duplicating machines of the kind wherein copies are taken from a flexible master sheet on to flexible copy material, e.g. sheets of paper fed singly into the machine. The invention is applicable particularly to hectog-raphic copying machines wherein copy sheets are moistened with a volatile solvent and are fed into the machine to take positive copies 'from'a mirror-script image formed on a master sheet in a spirit soluble dye. In machines of this kind it is usual to provide a printing couple consisting of a cylindrical drum and a counter-pressure roller, andthe master sheet is wrapped round-the drum and is secured thereto by a device referred tom the art-as a clip. 'Normally copies can betaken on to copy sheets of a length not greater than the circumference of the drum and in practice the length of the master sheet is restricted for well known reasons to somewhat less than thedrum circumference. It is often desired to'take copies on much longer copy sheets and in one existing method of doing this a master sheet is used which is longer than the drum circumference and this master sheet is secured to the drum by the clip andis then fed into the machine the slack being taken up by hand at the same time as the leading portion of'the master sheet is being wrapped round the drum and whilst the copy sheet is simultaneously being fed to the printing couple. Such method entails manual handling of the copy sheet in each printing operation and is thereforeslow and costly to operate.

It is an object of the present invention to devise a machine which is capable of taking copies from master sheets of greater than the normal length without manual handling of the master sheet. Furthermore, it is an object of the present invention to devise a hectographic copying machine which can take-anabnormally long master sheet and which may be adapted for automatic drive to take oif any desired number of copies in succession without disturbing the master sheet.

According to the invention this object is achieved by providing conveying means for the master sheet and clip whereby the total length of the master sheet to be'accommodated can be increased beyond that n'ormallyavailable in a printing drum. In a preferred embodiment of the invention the master clip and with it the master sheet are carried by an endlessconveyon'which may be chain or belt driven from a hand crank or a power driven shaft through suitable gearing so'that the master sheet travels between a non-driven pressure roller suitably situated below the path of the master sheet and an upper pressure roller, also non-driven, placed insidethepath of the clip and master sheet. Means are provided for ensuring that the clip which secures the leading edge of the master sheet is able to pass between the upper and 'lower pressure rollers whilst also arranging that these pressure rollers apply the printing pressure at the proper time between the master sheet and copy sheetto obtain the impression or impressions. A preferred arrangement is one in which the freely rotatable upper and lower pressure rollers are nited States Patent 0 2,884,854 Patented May 5, 1959 arranged normally to be in contact to apply the printing pressure and one of these rollers, most conveniently the upper pressure roller, is arranged to be moved away from the path of the clip at the appropriate time in the printing cycle. For this purpose the upper pressure roller is mounted in bearings at the forward end of two parallel rock levers arranged one at each side of the machine and cam means are arranged to raise and lower the said freely rotatable upper pressure roller at the appropriate times.

Means are also provided for ensuring that the master clip and master sheet return to a determined registration position ready for receipt of afresh copy sheet after each printing operation. Such means must also be timed to cooperate in the correct manner with means for automatically feeding each copy sheet to the registration position.

It is an advantage to make use, as far as possible, of the types of transmission gear and clutch control arrangements already used in-existing drum type machines. If this is done the problem of correctly timing the travel of the clip and the automatic feed mechanism is different from that in the most generally used drum type machines Where, the travel of the clip is equal to a single drum revolution and, in general, equivalent to one revolution of the drum clutch shaft. The present invention pro vides means for adaptingsuch existing-driving and clutch control arrangements to an endless clip conveyor, by arranging that the clutch shaft shall make more than one revolution, corresponding to the increased travel of the clip, in each printing cycle. Where automatic sheet feeding means are employed, such means are driven in timed relation with the clutch shaft revolutions. Accordingly the invention provides means for suiting the frequency of the sheet feeding operations to'the ratio of the-number of revolutions of the said clutch shaft in each complete printing cycle.

The main features of the construction according to -the invention will now be described as applied to one example of a rotary hectographic duplicatingmachine having a power drive for the clip conveyor operating through a one-revolution clutch which is automatically operated to bring the clip conveyor to rest in the registration position after each working cycle.

In the accompanying drawings:

Figure l is an elevation of the left hand side of the machine.

Figure 2 is an elevation of the right hand side of the machine.

'Figure 3 is a. plan view.

Figure 4-is an elevation showing in more detail one form of clutch which may be used in a power driven machine.

The machine comprises main side frames 1 and 2 which support in a known manner the bearings for the various movingparts of the machine, and these side frames have rearward extensions 3 and 4 respectively to support additional'bearings for the clip conveyor and for other purposes to be described below.

The main frames 1 and 2 carry bearings for the main conveyor shaft 5 which may be, and preferably is, situated in a position corresponding to thatwhich would be occupied by the drum shaft in a drum type machine, and is driven from an electric motor (not shown) through suitable reduction gearing and a'clutch to be referred to below. This shaft carries a pair of chain sprockets 6 and 7 keyed thereto whilst rearwardly placed stub shafts 8 journalled in bearings in the frame extensions 3 and 4 carry a further pair of sprockets 9 and 10 of smaller diameter. Chains 11 and 12 passing over these sprockets form a continuous conveyor for the master clip 13 which extends parallel to the main conveyor shaft and is secured at each side to each of thepair of chains passing over the sprockets. In order to facilitate the installation of the clutch mechanism (to be described below) and to allow room for movement of the impression rollers, the circumference of the forward pair of sprockets 6 and 7 is preferably such that the path of the clip conveyor when passing round these sprockets coincides approximately with the cylindrical surface of a normal printing drum, for example about /2 inches diameter, whilst the circumference of the rearwardly situated sprockets 9 and 10 and the distance of their axis from the driving axis are such that the total length of the path travelled by the clip during each printing cycle to bring it each time into the normal registration position is equal to twice the circumference of the driving sprockets, i.e. so that each complete cycle of operations corresponds to two revolutions of the main conveyor shaft 5.

The printing pressure is applied between the master sheet and the copy sheet by a pair of impression rollers 14, 15. The lower pressure roller 14 is conveniently of the kind normally used in a drum type machine and is mounted in known manner on rock arms 16 (Fig. 4) for slight upward and downward motion to adjust the printing pressure. The upper pressure roller is arranged eccentrically of the main conveyor shaft preferably downwardly and forwardly thereof, and is carried in bearings on the ends of two rock levers 17, 18 pivoted on a fixed axis 19 and anchored forwardly thereof by tension springs 20 (Fig. 2) tending to raise the upper pressure roller 15 away from the lower pressure roller 14. The clip 13 must pass between the upper and lower pressure rollers once for each two revolutions of the conveyor shaft 5, and the rock levers 17, 18 carrying the upper pressure roller 15 are arranged to be normally depressed by disc cams 21 which engage cam follower rollers 22 on the said rock levers and which allow the rock levers to be raised and lowered at the appropriate times in the printing cycle. The cams 21 are shown with a single dwell but obviously two or more dwells could be provided if necessary. The said disc cams are secured to a cam shaft 23 which is placed rearwardly of the main conveyor shaft 5 and is driven from such shaft 5 through a 2:1 reduction spur gear 24, 25.

The clip 13 is shown in Fig. 1 normally at rest in a predetermined forward position, known as the registration position for printing and which may, or may not coincide with the position in which the master sheet can be changed. This registration position of the clip is primarily determined, as is well known in the art by the design of the sheet feeding and moistening arrangements, and need not be discussed in detail. Since the clip must be returned to the registration position after each printing operation, a clutch arrangement is necessary which will operate once in each two revolutions of the main conveyor shaft. Although there are various ways in which this might be achieved, it is most convenient to use a one-revolution clutch in conjunction with a trip device for halving the frequency of the clutch operation and one arrangement of this kind will now be indicated.

Figure 4 indicates the general arrangement of a one revolution clutch which may be used for controlling revolutions of the main conveyor shaft 5. A clutch plate 26 carrying a clutch pawl 27 is secured to the left-hand end of shaft 5, whilst a clutch ratchet wheel 28 keyed to a tubular driving shaft 47 is mounted for free rotation about the axis of shaft 5 and is driven by suitable reduction gearing 29, 30 from an electric motor (not shown). The pawl 27 is biased towards engagement with the clutch ratchet wheel 28 by means of a spring 31 but is normally held disabled by a control pawl device so that the main conveyor shaft 5 is stationary. The control pawl device consists of a clutch control pawl 32 and a locating pawl 33 both pivoted on a stud 34 in the left hand main frame and both biased towards the clutch plate by means of a spring 35 acting on pawl 32 and a further spring 35a between pawl 32 and pawl 33. The position of pawls 32 and 33 is controlled by a lever 36 keyed to a clutch control 4 shaft 37 which extends across the width of the machine and is journalled in the side frames 1 and 2. The pawls 32 and 33 are shown in the engaged position, with the nose of pawl 32 resting on the heel of the clutch pawl 27 to hold it disengaged and with the nose of the locating pawl 33 engaged in a notch 26a of the clutch plate 26 to prevent movement thereof in the clockwise direction. The type of clutch above described is adapted normally to be engaged by momentary tripping of lever 36 and to reengage automatically so as to allow only one revolution of the conveyor shaft 5. Since, however, the main conveyor shaft 5 must perform two complete revolutions in each printing cycle means are provided for delaying the disengagement of the clutch until the end of the second revolution of the conveyor shaft. For this purpose a trip block 38, Fig. 2, carried on the conveyor chain 12 adjacent the right-hand side frame of the machine, co-operates with a trip lever 39 which is pivoted in the side frame 2 and which has an arm 40 adapted to be placed in the path of the said trip block 38. A manual clutch control member 48 is operatively connected to the clutch control shaft 37 through a lever 41 which is pivoted at 41a and linked to the shaft 37 by a connecting rod 42 and lever 43. Clutch control shaft 37 is normally biased counter-clockwise, Fig. 4, by spring 35 pulling roller 44 of pawl 32 against lever 36. When clutch control member 48 is operated to engage the clutch through the linkage 41, 42, 43

, and control shaft 37, a latch arm 45 carried by the trip lever 39 drops over a roller 46 on lever 43 to lock the said lever in its right hand position and at the same time to place the trip arm 40 in the path of the trip block 38. The clutch 27, 28 is thereby prevented from disengaging at the end of the first revolution of the conveyor shaft 5 and is only released by the lifting of the latch arm 45 of the trip lever when the trip block 38 strikes the trip arm 40 of the lever 39 during the second complete revolution of the conveyor shaft 5. The clutch will then automatically disengage at the end of this second revolution to bring the clip conveyor to rest in its normal registration position.

The machine is preferably provided with an automatic sheet feeding and copy sheet moistening device driven from the main conveyor shaft 5 and means are provided according to the invention for synchronising this automatic feed with each cycle of travel of the clip conveyor. The automatic sheet feeding and moistening device consists of a pair of rollers 50, 51, Fig. 4, the upper one 50 of which serves to moisten the upper surface of the copy sheet and is driven in timed relation with the shaft 5 by the following mechanism.

A toothed feed sector 52, Fig. 1, drives a pinion 53 coupled through a one-way clutch (not shown) to the upper feed roller 50. The feed sector 52 is reciprocated by means of an adjustable connecting rod 54 coupled to a three armed lever 55 which is rocked by a cam 56 keyed to shaft 5 (Fig. 4) through the intermediary of a cam follower roller 57 carried on one of the arms 58 of the three armed lever. The general arrangement of a feeding and moistening roller drive of this kind as applied to a drum type of machine is disclosed in our British patent specification No. 682,842 and no further detailed explanation is necessary here. This feed mechanism will normally operate once in each revolution of the conveyor shaft 5, and mechanism is therefore provided for rendering the feed mechanism ineffective in each second revolution of the two-revolution cycle of shaft 5. This mechanism comprises a latch 59 pivoted at 60 in the left-hand side frame of the machine and biased clockwise by a spring 61 (Fig. 1). Secured to the latch is a trip lever 62 which is placed in the path of a second trip block 63 carried at a convenient point on chain 11 of the conveyor. The arrangement is such that on the forward feed stroke of the feed sector 52, a pin 64 carried on the forward end of the connecting rod 54 engages under a notch in the latch 59 which thereby locks the said connecting rod in'its forward positionand at the same time places the trip lever 62 in-the pathof the trip block 63. The feed sector '52 is thus prevented from returning until, at a convenient point in the second revolution of shaft 5, the trip block 63 strikes the trip lever 62 to release the latch 59. The connecting rod having been released, the feed sector can now return in preparation for a fresh feeding stroke.

With the arrangement as above described it will be understood that themain drive for'the master sheet conveyor and the drive for the feed rollers are mutually timed such that atthe end of the forward feeding stroke of the feed rollers the leading edge of a copy sheet is stationary in the gap between'the impression rollers 14 and 15 and that the upper roller is then allowed to descend to grip the leading edge of the copy sheet. Thereafter the copy sheet is drawn round with the master sheet bythe conveyor, and the tail of the copy sheet is drawn through the feeding rollers 50, 51 which rotate to overrun the one-way clutch, normally fitted to roller 50, the small amount of friction between the copy sheet and the said rollers serving to apply the necessary tension to the copy sheet. Thus, the delay in returning the feed sector 52 does not affect the subsequent completion of the feeding operation already begun by the forward stroke of sector 52.

By an arrangement such as above described copies can be taken from master sheets which may be any convenient multiple of the normal length of master sheets employed on drum type machines by choosing the length of the endless conveyor to suit the gearing ratios.

The master sheet is secured to the conveyor by the clip 13 and may be supported for at least a part of its travel by a sheet metal apron 65, Fig. 3. The clip comprises a backing strip of suitable material, for example mild steel, and a clamping strip of the same material secured to each other and guided for relative movement so that the clamping strip may be opened in a direction parallel to the direction of motion of the conveyor. For this pur pose the backing strip is provided with an upstanding clamping ledge and the clamping strip is provided with an overhanging ledge these two ledges having clamping surfaces at right angles to each other between which the leading edge of the master sheet is to be gripped. For securing and guidingthe two strips in relation to each other the backing strip is provided at intervals with pins extending at right angles to the length of the strip and parallel to the general plane thereof, whilst the clamping strip is bored with guiding holes to receive these pins. Means are provided for ensuring a snap action of the clip when closed and opened, such means comprising spring urged balls housed in holes in the clamping strip and arranged to snap into depressions provided in the backing strip, such depressions being placed in positions which will determine the fully opened position of the clamping strip and the fully closed position respectively. The guiding pins above referred to also prevent the leading edge of the master sheet from penetrating beyond the two clamping surfaces provided between the backing strip and the clamping strip. The cross-section of the clip is kept as thin as possible to reduce weight and also to allow the clip carrying the master sheet to pass between the upper and lower pressure rollers.

Although the invention has been referred to above as applied to a hectographic copying machine it will be understood that the structure may also be applied to other types of printing machine employing different kinds of master sheet.

We claim:

1. In a hectographic duplicating machine, an endless conveyor for a master sheet arranged for movement around an elongated loop-like path, a master clip carried by and extending transversely across the width of said conveyor for attaching a master sheet to said conveyor, a pair of impression rollers comprising a first pressure roller locatedoutside said endless conveyor path and a second-pressure roller located inside said endless conveyor path and controlled means for applying pressure between said impression rollers in timed relation to the movement of said endless conveyor and for re leasing said impression rollers from applied pressure at least during'the period when said clip is passing between said rollers.

2. In a hectographic duplicating machine, an endless conveyor for a master sheetarranged for movement around an elongated loop-like path, a master clip carried by and extending transversely across the Width of said conveyor for attaching a master sheet to said conveyor, a pair' of impression rollers comprising a first pressure roller 'located outside said'endless conveyor path and a se'cond'pressure roller parallel with said first roller and located inside said endless conveyor path,

said second'pre'ssure roller being mounted in a movable support'structure" for'movem'enttowards and away from said first roller and controlled means for operating said movable support structure in timed relation to the movement of said endless conveyor to apply pressure between said rollers during a part only of each revolution of said conveyor and to remove such pressure at least during the period when said master clip is passing between said rollers.

3. In a hectographic duplicating machine, an endless conveyor for a master sheet, said conveyor comprising a pair of spaced apart flexible members passing around the peripheries of spaced apart rotatable means, a master sheet securing clip extending transversely between and attached to each of said endless flexible members for rotation therewith, a pair of impression rollers comprising a first pressure roller located inside said endless conveyor and in between said parallel flexible members and a second pressure roller disposed parallel with and opposite said first roller outside said endless conveyor, fixed bearing supports for one of said pressure rollers, movable supporting arms having bearings for supporting the other of said pressure rollers and cam control means for moving said supporting arms in timed relationship to the movement of said clip on said endless conveyor whereby printing pressure is set up between said impression rollers for the major part of each revolution of said endless conveyor and by which such applied printing pressure is released at least at the instant when said clip is passing between said rollers.

4. In a hectographic duplicating machine, an endless conveyor for a master sheet, said conveyor comprising a first pair of co-axial rotatable sprocket wheels, a second pair of co-axial rotatable sprocket wheels spaced from said first pair and a pair of endless chains passing around the peripheries of said first and second sprocket wheels, a master sheet securing clip extending transversely between and attached at each end to said chains for rotation therewith, a pair of impression rollers comprising a first pressure roller located inside the path traversed by said endless conveyor chains and a second pressure roller disposed parallel with and opposite said first roller outside said endless conveyor path, fixed bearing supports for supporting said second pressure roller, movable supporting arms having bearings for supporting said first pressure roller and cam control means for moving said supporting arm in timed relationship to the movement of said endless conveyor chains whereby printing pressure is set up between said impression rollers for the major part of each revolution of said endless conveyor and by which said first pressure roller is moved away from said second pressure roller at least at the instant when said clip is passing between said rollers.

5. In a hectographic duplicating machine, a conveyor device for a master sheet, said conveyor device comprising an endless flexible conveyor passing around the periphery of a first rotatable member secured to a conveyor driving shaft and a second rotatable member spaced from said first rotatable member, the length of said conveyor being to an integral number of times the peripheral dimension of said first rotatable member, a transverse master sheet securing clip attached to said endless flexible conveyor for rotation therewith, a pair of impression rollers comprising a first pressure roller located inside the loop of said endless conveyor and a second pressure roller disposed parallel with and opposite said first roller outside said endless loop of said endless conveyor, fixed bearing supports for one of the said pressure rollers, movable supporting arms having bearings for supporting the other of said pressure rollers, cam control means for moving said supporting arms in timed relationship to the movement of said clip whereby printing pressure is set up between said impression rollers for the major part of each revolution of said endless conveyor and whereby said applied printing pressure is released at least at the instant when said clip is passing between said rollers, a drive shaft, a driving connection between said drive shaft and said conveyor driving shaft, said driving connection including a one-revolution clutch device on said conveyor driving shaft and control means for maintaining said clutch in driving engagement for a number of revolutions of said driving shaft equal to said integral number by which said conveyor length is greater than said peripheral dimension of said first rotatable member.

References Cited in the file of this patent UNITED STATES PATENTS 1,906,374 Gestener May 2, 1933 2,387,750 Davidson Oct. 30, 1945 2,436,765 Davidson Feb. 24, 1948 2,753,798 Babst July 10, 1956 FOREIGN PATENTS 409,152 Italy July 4, 1942 732,157 Great Britain June 22, 1955

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